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CROSS-REFERENCE TO RELATED APPLICATIONS
This is a Division of application Ser. No. 08/198,427, filed Feb. 22, 1994, now U.S. Pat. No. 5,505,953, which is a continuation-in-part of Ser. No. 08/118,833 filed Sep. 7, 1993 (now U.S. Pat. No. 5,342,620), which is a continuation of Ser. No. 07/879,435 filed May 6, 1992, now abandoned.
BACKGROUND OF THE INVENTION
This invention relates to the use of borate-polyol complexes in ophthalmic compositions. In particular, these complexes are useful as buffers and/or antimicrobial agents in aqueous ophthalmic compositions, including those ophthalmic compositions containing polyvinyl alcohol.
Ophthalmic compositions are generally formulated to have a pH between about 4.0 and 8.0. To achieve a pH in this range and to maintain the pH for optimal stability during the shelf life of the composition, a buffer is often included. Borate is the buffer of choice for use in ophthalmic compositions, since it has some inherent antimicrobial activity and often enhances the activity of antimicrobials; however, when polyvinyl alcohol (PVA) is also an ingredient in the composition, borate and PVA form a water-insoluble complex which precipitates out of solution and acts as an irritant in the eye. This incompatibility of borate and PVA in contact lens solutions is well-known, and has been discussed, for example, in an article by P. L. Rakow in Contact Lens Forum, (June 1988), pages 41-46. Moreover, borate buffer cannot be effectively used below pH 7.0 due to its low buffering capacity to lower pH.
Since borate is incompatible with PVA ophthalmic compositions containing PVA are generally buffered with acetate, phosphate or other buffers. There are disadvantages to using these alternative buffers: for example, acetate is a weak buffer (pK a of about 4.5), so a relatively large amount is needed; on the other hand, phosphate is a good buffer but, when used in concentrations generally found in ophthalmic formulations, it reduces the antimicrobial activity of preservatives.
It is well known that small organic compounds, such as benzalkonium chloride (BAC), chlorhexidine, thimerosal have excellent antimicrobial activity; however, it is now known that these small organic antimicrobials are often toxic to the sensitive tissues of the eye and can accumulate in contact lenses, particularly soft, hydrophilic contact lenses. More recently, polymeric antimicrobials such as Polyquad® (polyquatemium-1) and Dymed® (polyhexamethylene biguanide) have been used in contact lens care products as disinfectants and preservatives. While these polymeric antimicrobials exhibit a broad spectrum of antimicrobial activity, they generally have relatively weak antifungal activity, especially against Aspergillus niger and Aspergillus fumigatus.
A need therefore exists for ophthalmic compositions which have an optimal pH for stability and efficacy, but whose antimicrobial efficacy is not compromised.
SUMMARY OF THE INVENTION
This invention provides such ophthalmic compositions. The ophthalmic compositions of the present invention comprise borate-polyol complexes which have surprisingly been found to have increased antimicrobial activity as compared to boric acid or its salts, particularly with respect to organisms such as A. niger. Moreover, these complexes unexpectedly increase the antimicrobial efficacy of other antimicrobial agents when used in combination.
The borate-polyol complexes are formed by mixing boric acid and/or its salts with polyols, such as mannitol, glycerin or propylene glycol, in an aqueous solution. The resultant solution may then be used as a buffer and/or antimicrobial agent in aqueous ophthalmic compositions, even where such compositions also contain PVA. The borate-polyol complexes of the present invention are also useful in unpreserved saline solutions.
The borate-polyol complexes of the present invention are particularly useful as adjunctive disinfecting agents in contact lens disinfecting solutions containing monomeric quaternary ammonium compounds (e.g., benzalkonium chloride) or biguanides (e.g., chlorhexidine) or polymeric antimicrobials, such as polymeric quaternary ammonium compounds (e.g., Polyquad®, Alcon Laboratories, Inc., Fort Worth, Tex.) or polymeric biguanides (e.g., Dymed®, Bausch & Lomb, Rochester, N.Y.).
The compositions of the present invention may optionally contain PVA; such compositions are particularly useful in contact lens care products which are targeted for wearers of rigid gas-permeable contact lenses (RGPs), who often complain of discomfort. PVA is a viscosity enhancer and is used extensively in all types of RGP products in order to improve the comfort and wearing time of RGPs. PVA is also extensively used as a viscosity enhancer for pharmaceutical ophthalmic compositions such as eye drops, gels or ocular inserts.
DETAILED DESCRIPTION OF THE INVENTION
As used herein, the term "borate" shall refer to boric acid, salts of boric acid and other pharmaceutically acceptable borates, or combinations thereof. Most suitable are: boric acid, sodium borate, potassium borate, calcium borate, magnesium borate, manganese borate, and other such borate salts.
As used herein, and unless otherwise indicated, the term "polyol" shall refer to any compound having at least two adjacent --OH groups which are not in trans configuration relative to each other. The polyols can be linear or circular, substituted or unsubstituted, or mixtures thereof, so long as the resultant complex is water-soluble and pharmaceutically acceptable. Such compounds include sugars, sugar alcohols, sugar acids and uronic acids. Preferred polyols are sugars, sugar alcohols and sugar acids, including, but not limited to: mannitol, glycerin, propylene glycol and sorbitol. Especially preferred polyols are mannitol and glycerin; most preferred is mannitol.
The water-soluble borate-polyol complexes of the present invention may be formed by mixing borate with the polyol(s) of choice in an aqueous solution. These complexes can be used in conjunction with other known preservatives and disinfectants to meet preservative efficacy and disinfection standards. In such compositions, the molar ratio of borate to polyol is generally between about 1:0.1 and about 1:10, and is preferably between about 1:0.25 and about 1:2.5. The borate-polyol complexes are particularly useful in unpreserved salines to meet preservative efficacy standards. In these unpreserved salines, the molar ratio of borate to polyol is generally between about 1:0.1 and about 1:1, and is especially between about 1:0.25 and about 1:0.75. Some borate-polyol complexes, such as potassium borotartrate, are commercially available.
The borate-polyol complexes are utilized in the compositions of the present invention in an amount between about 0.5 to about 6.0 percent by weight (wt %), preferably between about 0.5 to 3.0 wt %, more preferably between about 1.0 to about 2.5 wt %, and most preferably between about 1.0 to about 2.0 wt %. The optimum amount, however, will depend upon the complexity of the product, since potential interactions may occur with the other components of a composition. Such optimum amount can be readily determined by one skilled in the formulatory arts.
The compositions of the present invention useful with RGPs or compositions such as eye drops, gels or ocular inserts will preferably also contain PVA or other viscosity-enhancing polymers, such as cellulosic polymers or carboxy vinyl polymers. PVA is available in a number of grades, each differing in degree of polymerization, percent of hydrolysis, and residual acetate content. Such differences affect the physical and chemical behavior of the different grades. PVA can be divided into two broad categories, i.e., completely hydrolyzed and partially hydrolyzed. Those containing 4% residual acetate content or less are referred to as completely hydrolyzed. Partially hydrolyzed grades usually contain 20% or more residual acetate. The molecular weight of PVA's vary from 20,000 to 200,000. In general, PVA used in ophthalmic products has an average molecular weight in the range of 30,000 to 100,000 with 11% to 15% residual acetate. Compositions of the present invention generally contain such types of PVA at a concentration less than about 10.0 wt %, preferably between about 0.1 and about 1.4 wt % and most preferably at a concentration of about 0.75 wt %.
EXAMPLE 1
The water-soluble borate-polyol complexes of the present invention may be prepared as illustrated below.
__________________________________________________________________________ FORMULATION (% weight/volume)INGREDIENT A B C D E F G H__________________________________________________________________________Boric acid 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.35Sodium 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11borateMannitol 0.5 1.0 1.5 2.0 -- -- -- --Glycerin -- -- -- -- 0.5 1.0 1.5 20Na.sub.2 EDTA 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1Purified q.s. q.s. q.s. q.s. q.s. q.s. q.s. q.s.WaterHCl/NaOH pH 7.4 pH 7.4 pH 7.4 pH 7.4 pH 7.4 pH 7.4 pH 7.4 pH 7.4Polyquad ® 0.001 + 0.001 + 0.001 + 0.001 + 0.001 + 0.001 + 0.001 + 0.001 + 10% xs 10% xs 10% xs 10% xs 10% xs 10% xs 10% xs 10% xs__________________________________________________________________________
Preparation:
Formulations A-H were prepared as follows. Tubular, labeled and calibrated 150 milliliter (mL) beakers were each filled with about 90 mL of purified water. Boric acid, sodium borate and mannitol or glycerin were then added and dissolved by stirring the solution for about 25 minutes. At this time, disodium EDTA (ethylene diamine tetraacetic acid) was added with stirring. Purified water was added to bring the solutions almost to 100% (100 mL), pH was adjusted to approximately 7.4 and the osmolality was measured. Polyquad® was then added and the volume brought to 100% by the addition of purified water. pH was again measured and adjusted, if necessary, and the osmolality was measured again.
It is not always necessary to have an isotonic solution; however, if there is a need to have an isotonic solution, the osmolality can be adjusted by incorporating polyol with OH groups in trans position, sodium chloride, potassium chloride, calcium chloride or other osmolality building agents which are generally acceptable in ophthalmic formulations and known to those skilled in the art.
EXAMPLE 2
Aqueous ophthalmic compositions of the present invention may be prepared using the formulations illustrated below.
__________________________________________________________________________ FORMULATION (percent by weight)INGREDIENT 1 2 3 4 5 6 7 8 9__________________________________________________________________________PVA 0.75 1.4 0.75 0.75 0.75 0.75 0.75 0.75 0.75Hydroxyethyl cellulose -- -- 0.75 0.28 0.28 0.28 0.28 0.75 0.75(HEC)Mannitol 2.0 2.0 2.0 2.0 2.0 2.0 0.5 2.0 2.0Boric acid 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.35Sodium borate 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11Edetate disodium 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1Sodium chloride 0.09 0.09 0.09 0.09 0.45 0.09 0.09 0.09 0.09Polyquad ® 0.001 0.001 0.001 0.001 0.001 0.001 0.001 -- --Sucrose -- -- -- -- -- 2.5 -- 2.5 2.5Polyhexamethylene -- -- -- -- -- -- -- 0.0005 --biguanideBAC -- -- -- -- -- -- -- -- 0.004__________________________________________________________________________
Preparation:
Formulations 1-9 were prepared as follows. A first solution (Solution A) was prepared by adding 500 mL of warm purified water to a calibrated two liter aspirator bottle equipped with a magnetic stirrer. PVA and hydroxyethyl cellulose were then added to Solution A and the contents dispersed by stirring. After dispersal of the polymers, a filter assembly was attached to the aspirator bottle (142 mm Millipore filter holder with 0.2μ filter), and this whole apparatus autoclaved at 121° C. for 30 minutes. Solution A with the filter assembly attached was then allowed to cool to room temperature with stirring. A second solution (Solution B), was prepared in a 500 mL beaker containing 300 mL of purified water by adding boric acid, sodium borate and mannitol and dissolving the contents by stirring for 25 minutes. Edetate disodium, sodium chloride, preservatives and other osmolality-building agents, as necessary, were added to Solution B and the contents dissolved with stirring. Solution B was then sterile filtered into the aspirator bottle containing Solution A The pH of the resultant solution was then adjusted and the volume brought to 100% by sterile filtering purified water.
EXAMPLE 3
The following ophthalmic compositions of the present invention may also be prepared using the procedure detailed in Example 2.
__________________________________________________________________________ FORMULATION (percent by weight)INGREDIENT 10 11 12 13 14 15 16 17 18 19__________________________________________________________________________PVA 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4Naphazolene HCl 0.1 0.1 -- -- -- -- -- -- -- --Sodium -- -- -- 10.0 -- -- -- -- -- --sulfacetamideFluorometholone -- -- -- -- 0.1 -- -- -- -- --Gentamycin sulfate -- -- -- -- -- 0.4 -- -- -- --Levobunolol HCl -- -- 0.5 -- -- -- -- -- -- --Mydrysone -- -- -- -- -- -- 1.0 -- -- --Pilocarpine nitrate -- -- -- -- -- -- -- 1.0 1.0 1.0Sodium -- -- 0.4 -- -- -- -- -- -- --metabisulfiteMannitol 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 4.0 0.5Boric acid 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.5Sodium borate 0.11 0.11 0.11 0.11 0.11 0.11 0.11 0.11 -- --Sodium chloride 0.45 0.45 0.45 -- 0.45 0.45 0.45 0.45 -- --Edetate disodium 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1BAC 0.004 -- -- -- -- -- -- -- -- --Polyquad ® -- 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001__________________________________________________________________________
EXAMPLE 4
The following is a typical wetting and soaking composition of the present invention for use with RGPS.
______________________________________INGREDIENT AMOUNT (wt %)______________________________________PVA 0.75HEC 0.38Boric add 0.35Sodium borate 0.11Mannitol 2.0Potassium chloride 0.038Magnesium chloride 0.02Calcium chloride 0.0154Sodium chloride 0.09Polysorbate 80 0.005Polyquad ® 0.001NaOH and/or HCl pH 7.4Purified water q.s.______________________________________
Preparation:
In a suitable container containing approximately 30% of the final volume of purified water, PVA and HEC were added and dispersed. This solution was then autoclaved. The solution was allowed to cool to room temperature with stirring. In a separate container, containing approximately 50% of the final volume of purified water, boric acid and sodium borate were added, and dissolved, followed by mannitol. This second solution was then stirred for about 30 minutes, then potassim chloride, calcium chloride, magnesium chloride, sodium chloride, polysorbate 80 and Polyquad® were added, with stirring. The second solution was then added to the first solution via a 0.2μ filter. Last, the pH was adjusted to 7.4 and the volume brought to 100% with purified water.
EXAMPLE 5
The following is a typical daily cleaner composition of the present invention for use with RGPs and may be prepared in a manner similar to that detailed in Example 4.
______________________________________INGREDIENT AMOUNT (wt %)______________________________________Nylon 11 2.50Dextran 70 6.0Sodium borate 0.25Boric acid 0.50Miracare ® 2MCA 0.50PDMA-1 0.15Propylene glycol 10.0Polyquad ® 0.0055EDTA 0.10Mannitol 1.20NaOH and/or HCl pH 7.4Purified water q.s.______________________________________
EXAMPLE 6
The following is a typical wetting and soaking composition of the present invention which may be prepared in a manner similar to that detailed in Example 4.
______________________________________INGREDIENT AMOUNT (wt %)______________________________________Hydroxypropyl 0.72methylcellulose(Methocel ® E4M)Mannitol 1.0Sodium borate 0.11Boric acid 0.35Sodium chloride 0.19Polyquad ® 0.0011EDTA 0.10NaOH and/or HCl pH 7.4Purified water q.s.______________________________________
EXAMPLE 7
The following is a typical comfort drop composition of the present invention which may be prepared in a manner similar to that detailed in Example 4.
______________________________________INGREDIENT AMOUNT (w/v %)______________________________________PVA 0.75HEC 0.28Mannitol 2.0Sodium borate 0.11Boric acid 0.35Sodium chloride 0.152Polyquad ® 0.00082EDTA 0.10NaOH an/or HCl pH 7.4Purified water q.s.______________________________________
EXAMPLE 8
The following is a typical RGP cleaner composition of the present invention which may be prepared in a manner similar to that detailed in Example 4.
______________________________________INGREDIENT AMOUNT (wt %)______________________________________French Naturelle ® ES 2.5(Nylon 11)Hydroxyethyl cellulose 0.4Sodium borate, decahydrate 0.25Boric acid 0.50Mannitol 3.5Miracare ® 2MCA) 0.50Isopropyl alcohol (v/v) 10.0NaOH and/or HCl q.s. 7.4Purified water q.s.______________________________________
EXAMPLE 9
The following is a typical RGP wetting and/or soaking composition of the present invention., which may be prepared in a manner similar to that detailed in Example 4.
______________________________________INGREDIENT AMOUNT (wt %)______________________________________Methocel ® E4M 0.85Mannitol 2.00Sodium borate 0.11Boric acid 0.35Sodium chloride 0.19Disodium edetate 0.1Polyquad ® 0.001NaOH and/or HCl pH 7.4purified water q.s.______________________________________
EXAMPLE 10
The following study compared the antimicrobial preservative efficacy of two wetting, soaking and disinfecting solutions: one containing phosphate buffer Formulation A); and the other containing a borate-polyol complex of the present invention (Formulation B).
Formulations A and B are shown in the following table.
______________________________________ FORMULATION (wt %)INGREDIENT A B______________________________________PVA 0.75 0.75HEC 0.5 0.5Sodium phosphate 0.67 --Sodium biophosphate 0.017 --Boric acid -- 0.35Sodium borate -- 0.11Mannitol -- 2.0Disodium edetate 0.1 0.1Sodium chloride 0.458 0.153Polysorbate 80 0.005 0.005Benzalkonium chloride 0.01 0.01Purified water q.s. q.s.______________________________________
Formulations A and B were tested against FDA challenge organisms. The log reductions after 1 hour are tabulated below:
______________________________________ FORMULATION (log reduction)TEST ORGANISM A B______________________________________A. niger 2.1 4.4B. albicans 4.0 5.3P. aeruginosa 5.3 5.3S. aureus 5.5 5.2E. coli 5.5 5.5______________________________________
The results shown above indicate that Formulation B (containing borate-polyol complex) has a broader spectrum of activity than Formulation A (containing phosphate buffer), and has greater activity against certain organisms, such as A. niger.
EXAMPLE 11
The following study compared the antimicrobial preservative efficacy of two unpreserved saline solutions identical except that one contained a borate-polyol complex of the present invention (Formulation C) and the other contained the conventional borate buffer (Formulation D).
An organism challenge approach based on the British Pharmacopoeia ("BP") 1988 Test for Efficacy of Preservatives in Pharmaceutical Products was used to evaluate the antimicrobial preservative efficacy of Formulations C and D. Formulation samples were inoculated with known levels of A. niger and sampled at predetermined intervals to determine if the system was capable of killing or inhibiting the propagation of organisms introduced into the products.
Formulations C and D are shown in the following table.
______________________________________ FORMULATION (wt %)INGREDIENT C D______________________________________Boric acid 1.0 1.0Sodium borate 0.2 0.2Mannitol 1.5 --Sodium chloride -- 0.3Disodium edetate 0.1 0.1NaOH and/or HCl pH 7.4 pH 7.4Purified water q.s. q.s.______________________________________
The results indicated that there was a 3.1 log reduction of A. niger with Formulation C and only 1.2 log reduction with Formulation D after 7 days. Formulation C met the BP standards for preservative efficacy against A. niger, while Formulation D failed to meet the BP standards.
EXAMPLE 12
The following study compared the antimicrobial preservative efficacy of two disinfecting solutions identical except that one contained a borate-polyol complex of the present invention (Formulation E) and the other contained the conventional borate buffer (Formulation F).
An organism challenge approach based on the BP 1988 Test for Efficacy of Preservatives in Pharmaceutical Products was used to evaluate the antimicrobial preservative efficacy of Formulations E and F. Formulation samples were inoculated with known levels of A. niger and sampled at predetermined intervals to determine if the system was capable of killing or inhibiting the propagation of organisms introduced into the products.
Formulations E and F are shown in the following table.
______________________________________ FORMULATION (wt %)INGREDIENT E F______________________________________Boric add 0.3 0.35Sodium borate 0.11 0.11Mannitol 0.85 --Sodium citrate 0.56 0.56Citric acid 0.021 0.21Sodium chloride 0.48 0.48Pluronic P103 0.5 0.5Disodium edetate 0.05 0.05Polyquad ® 0.001 0.001NaOH and/or HCl pH 7.0 pH 7.0Purified water q.s. q.s.______________________________________
The results indicate that there was a 2.1 log reduction of A. niger with Formulation E and only 1.1 log reduction with Formulation F after 7 days. Formulation E met the BP standards for preservative efficacy against A. niger, while Formulation F failed to meet the BP standards.
The invention has been described by reference to certain preferred embodiments; however, it should be understood that it may be embodied in other specific forms or variations thereof without departing from its spirit or essential characteristics. The embodiments described above are therefore considered to be illustrative in all respects and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description.
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Water-soluble borate-polyol complexes are useful as buffers and/or antimicrobials in aqueous ophthalmic compositions, including those containing polyvinyl alcohol. These compositions have greater antimicrobial activity than comparable compositions containing typical borate buffers and unexpectedly increase the antimicrobial efficacy of other antimicrobial agents when used in combination. In addition, use of the borate-polyol complexes avoids the incompatibility problem typically associated with the combination of borate buffer and polyvinyl alcohol; therefore, the compositions disclosed herein may also contain polyvinyl alcohol.
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TECHNICAL FIELD
This invention relates to a method of integrated circuit manufacture which includes a step of etching organic materials that are useful as anti-reflection coatings in lithographic processes such as those used in deep ultraviolet lithography.
BACKGROUND OF THE INVENTION
As the dimensions of lithographically defined features become smaller, effects that were not significant at larger dimensions become important. For example, feature sizes may have identical size variations, and the variations may be acceptable for large features but unacceptable for small features because the variation is too high a percentage of the small feature size. Thus, critical dimension control is important for small feature size. Variations in dimensions may, of course, arise from many sources.
Integrated circuit features are typically defined with a lithographic pattern delineation process. A photosensitive material, commonly termed a resist, is formed on the substrate surface and portions of the resist are selectively exposed to radiation which creates a differential removal rate between the exposed and unexposed portions. The portions of the resist with the more rapid removal rate are now removed by, e.g., etching, to expose selected portions of the underlying substrate surface. Further processing, such as etching of the exposed substrate or ion implantation, etc., is now performed.
Ideally, all of the incident radiation travels a vertical path through the resist and is completely absorbed before reaching the bottom of the resist. This is, however, not always true in practice. Radiation may travel entirely through the resist and be reflected back into the resist. The reflection may be non-specular or from a non-horizontal surface, and the reflected radiation may be absorbed in portions of the resist that are not desirably exposed to radiation. The reflected radiation, of course, degrades the quality of the pattern delineation process because it is absorbed where it should not be absorbed.
To reduce the amount of reflected radiation, materials termed anti-reflection coatings have been developed. These materials are positioned underneath the resist. They are frequently organic polymers such as polyimides. Of course, polyimides are used for other purposes, such as interlevel dielectrics, in integrated circuit fabrication. For use as an interlevel dielectric, the polyimide frequently has to be patterned to form vias which expose portions of the underlying material. Of course, portions of the anti-reflection coating must also be patterned to expose the underlying substrate material. The use of polyimides in integrated circuits is discussed by Lai et al. in Industrial Engineering Chemical Product Research Development, 25, 1986, pp. 38-40. Consideration of the above shows that there must be an etching process for the polyimide.
Plasma etching of polyimides is discussed by Scott et al. in Journal of Vacuum Science and Technology, A8, May/June 1990, pp. 2382-2387. Scott used a mixture of CF 4 and O 2 and found that the addition of CF 4 increased the etch rate of the polyimide as compared to the rate obtained with only O 2 . The increased etch rate was attributed to both etching by the CF 4 and the formation of atomic O in the plasma by the CF 4 . Turban et al., Journal of the Electrochemical Society, 130, November 1983, pp. 2231-2236, also reported the etching of polyimide using O 2 and either CF 4 or SF 6 . Tepermeister et al., Journal of Vacuum Science and Technology, A9, May/June 1991, pp. 790-795, reported the etching of polyimides using Ar, O 2 and O 2 /F 2 plasmas. They reported that the etching process was a combination of gas phase plasma chemistry and plasma surface interactions. See also, Kogoma et al., Plasma Chemistry and Plasma Processing, 6, 1986, pp. 349-380, for a discussion of etching mechanisms of polyimide in O 2 /SF 6 plasmas.
Of course, methods for detecting the endpoint of plasma etching processes are also known. See, for example, U.S. Pat. No. 4,312,732, issued on Jan. 26, 1987 to Degenkolb et al.
Consideration of the results of the above processes indicates that there is a need for a method of etching polyimides which provides critical dimension control and provides for an optical endpoint capability.
SUMMARY OF THE INVENTION
A method of manufacturing an integrated circuit deposits a layer of an organic polymer on a substrate and forms a layer of resist on the surface of the organic polymer. The organic polymer is an anti-reflection coating. Selected portions of the resist are exposed to radiation and portions of the resist are selectively removed to expose selected portions of the organic polymer which are etched with a plasma comprising CHF 3 , a sputter component, and O 2 . The CHF 3 promotes polymer formation which inhibits etching while the sputter component removes the polymer. In an exemplary embodiment, the organic polymer comprises a polyimide. In a preferred embodiment, the CHF 3 and the sputter component have flow rates into the etching apparatus such that the rates of polymer formation and polymer removal by sputtering are approximately balanced. In another preferred embodiment, the sputter component comprises Ar.
BRIEF DESCRIPTION OF THE DRAWING
The FIGURE is a sectional view of a portion of an integrated circuit and is useful in explaining this invention.
DETAILED DESCRIPTION
The invention will be explained by reference to the FIGURE and a particular embodiment. For reasons of clarity, the elements depicted are not drawn to scale.
Depicted in the FIGURE are substrate 1 and features 3 on substrate 1, polyimide layer 5, and resist layer 7. As can be seen, the polyimide layer covers the features 3 and the substrate surface. The resist has been patterned to expose selected portions of the polyimide layer. Selected portions of the resist are exposed to radiation which creates different removal rates when the resist is subsequently exposed to a removal agent, such as a plasma having the composition which will be discussed. The organic polymer serves as an anti-reflection coating for the radiation. The term substrate is used to mean any material that lies underneath and supports another material. The substrate may be single crystal silicon, with or without an epitaxial layer, or it may be a metal or dielectric layer. The features may be any of the device features present in integrated circuit devices or electrical interconnections which may be on any level. The term polyimide is well known to those skilled in the art and represents a well-defined class of organic polymers. No further description is required.
The structure depicted will be readily fabricated by those skilled in the art. The device features are well known as will be readily fabricated. An appropriate polyimide will also be readily selected and put on the substrate. An adhesion promoter may be used, if desired. The polyimide functions, as mentioned, as an anti-reflection coating for the radiation used in the pattern delineation process. The thickness of this layer is a function of the wavelength of the radiation used in the lithographic process and of the optical properties, i.e., reflectivity of the substrate. Those skilled in the art will readily select an appropriate thickness. The resist will be formed and usually patterned using techniques that can define features having dimensions less than 0.5 μm. It is contemplated that patterning of features smaller than 0.5 μm will use deep ultra-violet radiation. Such techniques are known to those skilled in the art.
The polyimide layer is etched after the overlying resist has been patterned to expose selected portions of the polyimide. The etch apparatus used is conventional, but the plasma used comprises CHF 3 /Ar/O 2 . The CHF 3 promotes polymer formation on the exposed surfaces while the Ar acts as a sputter component which removes the polymer formed by the CHF 3 . The sputter component travels primarily in a vertical direction so that polymeric material on the sidewalls is not removed. The concentrations of CHF 3 and Ar in the plasma should be such that the rates of polymer formation and polymer removal by sputtering are approximately equal. Although precise concentrations in the plasma have not been measured, it has been found that the CHF 3 concentration should be between 10 and 35 percent of the total flow. Control of feature size is excellent for CHF 3 concentrations within this range.
The CHF 3 is also a desirable component of the plasma because it provides a convenient means for using optical endpoint detection. The F content of the plasma is monitored using well known techniques. When etching of the polyimide is finished, the F content of the plasma rises and etching can be terminated. Thus, etching is terminated when the F concentration reaches a predetermined level. The plasma also has good selectivity between the polyimide and the resist; in fact, selectivity of 1:1 has been obtained. Higher selectivities can be obtained but typically at the expense of slower polyimide etch rates.
Although the invention has been described by reference to a particular embodiment, variations will be evident to those skilled in the art. For example, the sputter component may be an inert gas other than Ar. Additionally, organic polymers other than polyimides may be used as the anti-reflection coating.
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A polyimide layer used in manufacturing semiconductor integrated circuits is etched in a plasma comprising O 2 , Ar, and CHF 3 . The plasma produces excellent critical dimension control and yields good resist to polyimide etching selectivity.
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ORIGIN OF INVENTION
The invention described herein was made in the performance of work under a NASA contract and is subject to the provisions of Section 305 of the National Aeronautics and Space Act of 1958, Public Law 85-568 (72 Stat. 435: 42 USC 2457).
This is a continuation-in-part of application Ser. No. 06/642,417 filed Aug. 20, 1984 now abandoned. This continuation-in-part is for the purpose of dividing out of the original application nonelected claims, and to add new matter and claims directed to the method of growing an oxide film on the backside of thinned backside-illuminated sensors.
FIELD OF THE INVENTION
This invention relates to photo sensors, and more particularly to improvements in the performance of thinned backside-illuminated CCDs for blue, ultraviolet, far ultraviolet, and low energy x-ray wavelengths.
BACKGROUND OF THE INVENTION
Charge coupled devices (CCDs) are the detectors of choice for a large number of terrestrial astronomical applications in the visible and near infrared, where high sensitivity and low noise are the important considerations. In addition to terrestrial use, such devices are now being (or will soon be) flown on several space-borne satellites and missions. In 1976, CCDs were selected as the detectors for the Hubble Space Telescope (HST) Wide Field/Planetary Camera (WF/PC). CCDs also are the detectors selected for the camera on the Giotto Mission to Halley's Comet, the Solid State Imager (SSI) on the Galileo Orbiter, and for the solar imaging cameras for the Shuttle-based Solar Optical Telescope (SOT) mission. Both Galileo and Giotto are visible imaging missions, while the devices for the SOT mission require response into the ultraviolet (UV), and the devices for WF/PC require response shortward to Lyman-α (λ=1216 Å). For these latter devices, the UV response was enhanced by using an evaporated organic phosphor film coating (coronene) which converts UV photons to the visible.
In the past several years there has been a surge of interest in the areas of UV, XUV, and x-ray instruments, imaging, and astronomy. This interest, coupled with an unexpected short wavelength instability of the quantum efficiency of the thinned backside illuminated CCDs used by WF/PC, has stimulated a detailed investigation of the short wavelength response (1 Å<λ<5000 Å) and performance potential of the CCD as a detector for this spectral region. It has now been demonstrated that uncoated devices are useful detectors with potential to achieve very high quantum efficiencies over the entire spectral range of 1 to 11,000 Å, (i.e., from the soft x-ray to the near IR).
The fundamental parameters which ultimately determine CCD performance are:
(1) Read Noise
(2) Charge Transfer Efficiency (CTE)
(3) Quantum Efficiency (QE)
(4) Charge Collection Efficiency (CCE)
At the present stage of development, it is now possible to consistently fabricate CCDs which have low read noise (in the 4 to 15 e - range) and excellent CTE performance (>0.99999). The means of achieving high QE and CCE, of which the CCD is capable, is the subject of this application.
As will be described more fully hereinafter, the present invention utilizes backside illumination of any thinned CCD, whether it be four-phase, three-phase, two-phase, uniphase or virtual-phase in a manner which yields theoretical quantum efficiency performance for blue, ultraviolet, far ultraviolet and low energy x-ray wavelengths. However, the specific embodiment to be described herein by way of example, and not by way of limitation, utilizes the three-phase CCD.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, a method is provided to promote quantum efficiency of a CCD imaging sensor for blue, ultraviolet, far ultraviolet and low energy x-ray wavelengths, comprised of the steps of overthinning the backside to remove all low resistivity substrate material into the high resistivity silicon, and subjecting the backside of the overthinned detector to an intense flood of ultraviolet radiation prior to using the sensor for imaging. The ultraviolet flooding preconditions the CCD for imaging yielding very high quantum efficiency for an extended period (years) of use if operated at a very low temperature, such as at nitrogen cooled temperature of -130°. The UV flood eliminates a "dead region" which is 6000 Å in extent in the form of an unwanted backside depletion well created by positive states at the Si-SiO 2 interface which result after thinning. During the process of UV flooding, electrons are photoemitted from the silicon into trapping centers on the immediate SiO 2 surface charging the backside negatively causing the backside potential well and dead region to collapse. An accumulation layer of holes near the Si-SiO 2 interface within the silicon creates an electric field gradient which directs photogenerated signal carriers to the frontside increasing the quantum efficiency of the CCD.
The SiO 2 layer which has the required characteristics (thickness and quality equivalent to or better than native oxide) which supports the backside charge and used in accumulating the backside illuminated CCD for QE enhancement can be quickly grown after thinning in about an hour (as compared to as much as two years or more for a mature native oxide) by exposing the backside of the sensor in a deionized steam at 95° C. after preparing the backside in accordance with the first part of this invention.
The novel features of the invention are set forth with particularlity in the appended claims. The invention will best be understood from the following description when read in conjunction with the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates schematically a buried channel CCD with an overthinned backside beyond the epitaxial interface subjected to intense UV radiation flooding yielding maximum quantum efficiency in accordance with one aspect of this invention.
FIGS. 2(a), (b) and (c) illustrate the conduction and valence bands within the silicon region of a thinned, overthinned and underthinned CCD.
FIG. 3 illustrates the conduction and valence bands of an overthinned CCD subjected to intense UV flooding in accordance with one aspect of this invention.
FIG. 4 is a plot of quantum efficiency as a function of UV flood time at different operating temperatures for a wavelength of 4000 Å.
FIG. 5 compares three-phase CCD quantum efficiency at various wavelengths as a function of wavelength after UV flooding with a three-phase CCD with coronene coating and with a virtual-phase CCD.
FIG. 6 shows the quantum yield (electrons generated/interacting photon) for a 100×100 pixel subarea within a corner of a three-phase CCD after backside flooding with UV. Overthinning produces a high quantum yield (3.1), while not thinning through the epitaxial interface produces less quantum yield (1.0 to 1.73), depending upon the thickness of substrate material left.
FIG. 7 is a graph of quantum efficiency at 4000 Å as a function of operating time for temperatures +20° C., -60° C. and -100° C.
FIG. 8 illustrates apparatus used in growing flash oxide onto the backside of a device in accordance with the present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
Before describing in detail preferred embodiments of the invention with reference to FIG. 1, additional backgroud information will first be given on thinned backside illuminated CCD structures with reference to FIGS. 2(a), (b) and (c).
Referring to FIG. 1, the photosensitive volume of a backside illuminated CCD is a layer of highpurity silicon 20, bounded on one side by an oxide layer 21, and gate structure 22, and on the other side by a thinned region 20a etched through a thick, low lifetime p + substrate 23 on which the device is fabricated.
For photons with long absorption lengths (i.e., wavelengths less than 10 Å or greater than 7000 Å), the quantum efficiency (QE) depends largely on the thickness of the photosensitive volume 20. (Quantum efficiency is the ratio of the number of electrons per pixel per second to the number of incident photons per pixel per second, which has units of electrons per incident photon.) Intermediate wavelengths have relatively short absorption lengths in silicon and silicon dioxide and, throughout this spectral region, the QE depends largely on the transparency and reflective properties of the layers that bound the photosensitive volume.
For optimum QE, the substrate of a CCD is thinned to allow direct backside illumination of the sensitive layer 20, as illustrated schematically in FIG. 2(a). In the thinning process used in the past, an accumulation layer of p + boron-doped silicon was intentionally left at the back surface to establish a field which aids the collection of charge. This results in an increase in QE in the 10 to 7000 Å range. The response throughout this range is a strong function of the surface condition and of the p + boron accumulation profile. Ideally, thinning to the proximity of the p 30 -p boundary 24 between the sensitive epitaxial p layer and the substrate will result in optimum backside illumination characteristics by providing the proper electric field gradient for directing signal charge to the frontside potential wells. There will always be an oxide film 26 formed on the surface of the thinned (etched) substrate by atmospheric oxidation of the etched surface following the process of removing etchant.
Overthinning into the sensitive epitaxial p layer 20, as shown in FIG. 2(b), will yield low responsivity in this wavelength range because the energy bands are bent downward by the positive trapped charge always found at the Si-SiO 2 interface 27. This downward band bending creates an unwanted backside potential well in a dead region (i.e., a depletion region) of approximately 6000 Å in depth. Electrons produced by photons penetrating less than 6000 Å will collect in this backside well and be lost through recombination at the Si-SiO 2 interface 27. Conversely, an excessively thick layer 28 of p + material shown in FIG. 2(c) will yield a low response due to recombination of short-lived minority carriers in the p + material. Therefore, an optimum boron profile exists that most effectively directs carriers away from the back surface without permitting substantial carrier recombination. This optimum p + layer is impossible to achieve in practice due to nonuniform thinning of the chip. (Absolute thinning accuracies of better than 2000 Å are required to produce devices that behave uniformly.)
A simple method has been discovered to promote backside accumulation of a CCD structured as shown in FIG. 1, i.e., without the p + boron layer 28, by overthinning the backside as shown in FIG. 2(b). It has been found that if the overthinned CCD is subjected to an intense flood of UV radiation, as indicated schematically in FIG. 1, a very high and uniform blue response can be achieved over the array.
The mechanism proposed to explain this blue enhancement is now discussed with reference to FIG. 3. Ultraviolet light causes photoemission of electrons from the valence band of the sensitive p epitaxial layer 20 into the conduction band of the adjacent SiO 2 film 26, charging the backside negatively. This causes the backside potential well shown in FIG. 2(b) to collapse, i.e., and produces an accumulation layer 18 of holes as shown in FIG. 3. In this condition, signal photoelectrons can proceed from the backside to the frontside without loss to a backside well.
The backside charging process can be monitored by measuring the QE at 4000 Å as a function of UV flood time, as shown in FIG. 4. Since roughly 40% of 4000-Å light is lost due to reflection at the silicon surface of the device, FIG. 4 shows that UV flooding technique achieves the full theoretical performance expected at this wavelength.
The improvement in QE is even more dramatic for shorter wavelengths. FIG. 5 shows the QE for a three-phase CCD after backside UV illumination. For comparison, the QE of a three-phase CCD with coronene coating and a frontside-illuminated virtual-phase CCD are also presented. Here the backside-illuminated sensor, which yields a QE of greater than 200%, is far superior to the coronene-coated device. The dramatic increase in QE for wavelengths shortward of 3000 Å is due to multiple e-h pair generation per photon and a decrease in backside reflectivity.
This finding is supported further by measurement of the quantum yield (electrons produced per interacting photon). FIG. 6 shows the quantum yield for a 100×100 pixel subarea at 1216 Å within a corner of a three-phase CCD after backside charging with UV light flood. Several different yields are observed, which have been correlated to regions of different boron accumulation layer thicknesses caused by uneven thinning. A low quantum yield is measured where the device is thick and recombination is high due to the p + layer 23. Areas thinned through the p + layer show very uniform UV response and near-theoretical quantum yield (3 e - /photon). It can be concluded at this wavelength that each photon charge packet (3 e - ) remains intact without recombination loss.
As FIG. 3 shows, 4.25 eV of energy is required to cause photoemission of electrons from the valence band of silicon into the conduction band of SiO 2 ; therefore, backside charging can only be achieved using wavelengths below 2915 Å. A light flood using 2537 Å (mercury lamp) has 0.7 eV more energy than is required for this process and works very well at room temperature. Charging at colder temperatures significantly increases the required UV flood time, and below -40° C. full charging cannot be usually achieved at 2537 Å (see FIG. 5). This effect has been attributed to a lack of additional thermal (kT) energy needed by the electrons to overcome the potential barrier of the SiO 2 , which increases as the backside charges. It should be mentioned that corona discharge and nitrogen monoxide charging have been used successfully to provide full charging at cryogenic temperatures and offers advantages over UV flooding for some applications.
Stability of QE produced by backside charging is chiefly dependent on temperature. FIG. 7 shows QE at 4000 Å as a function of operating time for temperatures of +20°, -60°, and -100° C. The characteristics shown are attributed to the discharge of electrons from SiO 2 traps at higher temperatures. Thus operation at the lower temperatures results in improved stability, and it has been shown that very long-term stability (years) can be achieved at a temperature of -130° C. Most users of this innovation usually charge their CCDs just before use as a matter of standard practice.
The backside discharge rate has been found to increase with humidity. Therefore, to assure stable QE, this problem can be eliminated by housing the CCD in a dry environment (e.g., N 2 or vacuum).
After overthinning, as that term is defined with reference to FIG. 2(b) an oxide film is required to hold the backside charge when UV flooded. This oxide film can be produced as a natural consequence of long exposure to oxygen and water in the atmosphere, such as exposure over a period as long as two or more years. Such a naturally produced oxide film, called native oxide, has been used successfully in promoting the quantum efficiency of a CCD imaging sensor for blue, ultraviolet, far ultraviolet and low energy x-ray wavelengths, but it increases the time necessary to fabricate devices from a few months to a few years which is an unacceptable delay.
To shorten this time an oxide film is grown in about one hour on the surface of a device in the presence of deionized vapor at 95° C. as shown in FIG. 8. This one hour is insignificant when compared with the overall fabrication time of about three months for a complex device, such as a CCD. Also the oxide film grown has fewer positive charges than a native oxide, such as fewer Na + charges, a contaminating source which develops during a native oxide growth, and is of better quality, i.e., has fewer Si-SO 2 interface states to be discussed below.
This oxide film far exceeds the requirements of the technique for enhancing the quantum efficiency of a photo sensor, and may be used not only with backside charging, as described above, but also with a metal gate over the oxide film as described in a copending application Ser. No. 06/835,535 titled "CCD Imaging Sensor with Flashed Backside Metal Film," assigned to the assignee of the present invention. There an unbiased metal film over the oxide film permanently promotes backside charging, thus obviating the need to periodically flood the backside with UV radiation.
Referring to the quality of the oxide film, a feature more important than its thickness, it is necessary that the number of positive charges within the oxide film be minimized. These positive charges are of three kinds (sources), namely
(1) Mobile charge, Q m , such as positively charged sodium, Na + , which builds up as the oxide grows: a contaminant source.
(2) Trapped charge, Q t , similar to mobile charge, but spatially fixed near the Si-SiO 2 interface.
(3) Interface charge, Q it , which is caused by "dangling" bonds located at the Si-SiO 2 interface which occur when the Si lattice is abruptly terminated along a given plane to form a surface.
Minimizing the number of positive charges within the oxide is important to its quality. This is because the positive charges "tie-up" with the negative charges produced by backside UV flood charging or the flash gate as opposed to the free holes which make up the accumulation layer in the p-silicon that produces an electric field at the surface which sweeps signal electrons to the frontside where they are collected: i.e., the voltage drop across the silicon decreases as the number of positive oxide charges increase, lowering the overall QE of the CCD.
Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art. Consequently, it is intended that the claims be interpreted to cover such modifications and variations.
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A method to significantly increase the quantum efficiency (QE) of a CCD (or similar photosensor) applied in the UV, far UV and low energy x-ray regions of the spectrum. The increase in QE is accomplished by overthinning the backside of a CCD substrate beyond the epitaxial interface and UV flooding the sensor prior to use. The UV light photoemits electrons to the thinned surface and charges the backside negatively. This in turn forms an accumulation layer of holes near the Si-SiO 2 interface creating an electric field gradient in the silicon which directs the photogenerated signal to the frontside where they are collected in pixel locations and later transferred. An oxide film, in which the backside charge resides, must have quality equivalent to a well aged native oxide which typically takes several years to form under ambient conditions. To reduce the amount of time in growing an oxide of sufficient quality, a process has been developed to grow an oxide by using deionized steam at 95° C. which takes less than one hour to grow.
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TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to methods and systems for determining the mass flow rate of a fluid, and more particularly to the operation of mass flow controllers.
BACKGROUND OF THE INVENTION
Many industrial processes require precise control of various process fluids. For example, in the pharmaceutical and semiconductor industries, mass flow controllers are used to precisely measure and control the amount of a process fluid that is introduced to a process tool. A fluid can be any type of matter in any state that is capable of flow such as liquids, gases, and slurries, and comprising any combination of matter or substance to which controlled flow may be of interest.
Conventional mass flow controllers (MFCs) generally include four main portions: a flow meter, a control valve, a valve actuator, and a controller. The flow meter measures the mass flow rate of a fluid in a flow path and provides an electrical signal indicative of that flow rate. Typically, the flow meter may include a mass flow sensor and a bypass. The mass flow sensor measures the mass flow rate of fluid in a sensor conduit that is fluidly coupled to the bypass. The mass flow rate of fluid in the sensor conduit is related to the mass flow rate of fluid flowing in the bypass, with the sum of the two being the total flow rate through the flow path controlled by the mass flow controller.
FIG. 1 shows schematically a typical mass flow controller 100 that includes a block 110 , which is the platform on which the components of the MFC are mounted. A thermal mass flow meter 140 and a valve assembly 150 containing a valve 170 are mounted on the block 110 between a fluid inlet 120 and a fluid outlet 130 . The thermal mass flow meter 140 includes a bypass 142 through which typically a majority of fluid flows and a thermal flow sensor 146 through which a smaller portion of the fluid flows.
Thermal flow sensor 146 is contained within a sensor housing 102 (portion shown removed to show sensor 146 ) mounted on a mounting plate or base 108 . Sensor 146 is a small diameter tube, typically referred to as a capillary tube, with a sensor inlet portion 146 A, a sensor outlet portion 146 B, and a sensor measuring portion 146 C about which two resistive coils or windings 147 , 148 are disposed. In operation, electrical current is provided to the two resistive windings 147 , 148 , which are in thermal contact with the sensor measuring portion 146 C. The current in the resistive windings 147 , 148 heats the fluid flowing in measuring portion 146 to a temperature above that of the fluid flowing through the bypass 142 . The resistance of windings 147 , 148 varies with temperature. As fluid flows through the sensor conduit, heat is carried from the upstream resistor 147 toward the downstream resistor 148 , with the temperature difference being proportional to the mass flow rate through the sensor.
An electrical signal related to the fluid flow through the sensor is derived from the two resistive windings 147 , 148 . The electrical signal may be derived in a number of different ways, such as from the difference in the resistance of the resistive windings or from a difference in the amount of energy provided to each resistive winding to maintain each winding at a particular temperature. Examples of various ways in which an electrical signal correlating to the flow rate of a fluid in a thermal mass flow meter may be determined are described, for example, in commonly owned U.S. Pat. No. 6,845,659, which is hereby incorporated by reference. The electrical signals derived from the resistive windings 147 , 148 after signal processing comprise a sensor output signal.
The sensor output signal is correlated to mass flow in the mass flow meter so that the fluid flow can be determined when the electrical signal is measured. The sensor output signal is typically first correlated to the flow in sensor 146 , which is then correlated to the mass flow in the bypass 142 , so that the total flow through the flow meter can be determined and the control valve 170 can be controlled accordingly. The correlation between the sensor output signal and the fluid flow is complex and depends on a number of operating conditions including fluid species, flow rate, inlet and/or outlet pressure, temperature, etc.
The process of correlating raw sensor output to fluid flow entails tuning and/or calibrating the mass flow controller and is an expensive, labor intensive procedure, often requiring one or more skilled operators and specialized equipment. For example, the mass flow sensor may be tuned by running known amounts of a known fluid through the sensor portion and adjusting certain signal processing parameters to provide a response that accurately represents fluid flow. For example, the output may be normalized, so that a specified voltage range, such as 0 V to 5 V of the sensor output, corresponds to a flow rate range from zero to the top of the range for the sensor. The output may also be linearized, so that a change in the sensor output corresponds linearly to a change in flow rate. For example, doubling of the fluid output will cause a doubling of the electrical output if the output is linearized. The dynamic response of the sensor is determined, that is, inaccurate effects of change in pressure or flow rate that occur when the flow or pressure changes are determined so that such effects can be compensated.
A bypass may then be mounted to the sensor, and the bypass is tuned with the known fluid to determine an appropriate relationship between fluid flowing in the mass flow sensor and the fluid flowing in the bypass at various known flow rates, so that the total flow through the flow meter can be determined from the sensor output signal. In some mass flow controllers, no bypass is used, and the entire flow passes through the sensor. The mass flow sensor portion and bypass may then be mated to the control valve and control electronics portions and then tuned again, under known conditions. The responses of the control electronics and the control valve are then characterized so that the overall response of the system to a change in set point or input pressure is known, and the response can be used to control the system to provide the desired response.
When the type of fluid used by an end-user differs from that used in tuning and/or calibration, or when the operating conditions, such as inlet and outlet pressure, temperature, range of flow rates, etc., used by the end-user differ from that used in tuning and/or calibration, the operation of the mass flow controller is generally degraded. For this reason, the flow meter can be tuned or calibrated using additional fluids (termed “surrogate fluids”) and or operating conditions, with any changes necessary to provide a satisfactory response being stored in a lookup table. U.S. Pat. No. 7,272,512 to Wang et al., for “Flow Sensor Signal Conversion,” which is owned by the assignee of the present invention and which is hereby incorporated by reference, describes a system in which the characteristics of different gases are used to adjust the response, rather than requiring a surrogate fluid to calibrate the device for each different process fluid used.
Control electronics 160 control the position of the control valve 170 in accordance with a set point indicating the desired mass flow rate, and an electrical flow signal from the mass flow sensor indicative of the actual mass flow rate of the fluid flowing in the sensor conduit. Traditional feedback control methods such as proportional control, integral control, proportional-integral (PI) control, derivative control, proportional-derivative (PD) control, integral-derivative (ID) control, and proportional-integral-derivative (PID) control are then used to control the flow of fluid in the mass flow controller. A control signal (e.g., a control valve drive signal) is generated based upon an error signal that is the difference between a set point signal indicative of the desired mass flow rate of the fluid and a feedback signal that is related to the actual mass flow rate sensed by the mass flow sensor. The control valve is positioned in the main fluid flow path (typically downstream of the bypass and mass flow sensor) and can be controlled (e.g., opened or closed) to vary the mass flow rate of fluid flowing through the main fluid flow path, the control being provided by the mass flow controller.
In the illustrated example, the flow rate is supplied by electrical conductors 158 to a closed loop system controller 160 as a voltage signal. The signal is amplified, processed and supplied to the control valve assembly 150 to modify the flow. To this end, the controller 160 compares the signal from the mass flow sensor 140 to predetermined values and adjusts the proportional valve 170 accordingly to achieve the desired flow.
FIG. 2 illustrates a schematic block diagram of a typical mass flow controller 200 . The mass flow controller illustrated in FIG. 2 includes a flow meter 210 , a Gain/Lead/Lag (GLL) controller 250 , a valve actuator 260 , and a valve 270 .
The flow meter 210 is coupled to a flow path 203 . The flow meter 210 senses the flow rate of a fluid in the flow path, or in a portion of the flow path, and provides a raw flow signal indicative of the sensed flow rate. The raw flow signal is typically conditioned, that is, it is normalized, linearized, and compensated for dynamic response. A conditioned flow signal FS 2 is provided to a first input of GLL controller 250 . The conditioned flow signal FS 2 is also provided to a signal filter 220 , which provides appropriate signal levels as input to a display 225 , which displays the flow rate to an operator.
In addition, GLL controller 250 includes a second input to receive a set point signal SI 2 . A set point refers to an indication of the desired fluid flow to be provided by the mass flow controller 200 . The set point signal SI 2 may first be passed through a slew rate limiter or filter 230 prior to being provided to the GLL controller 250 . Filter 230 serves to limit instantaneous changes in the set point in signal SI 2 from being provided directly to the GLL controller 250 , such that changes in the flow take place over a specified period of time. It should be appreciated that the limiter or filter 230 may be omitted, and that any of a variety of signals capable of providing indication of the desired fluid flow is considered a suitable set point signal. The term set point, without reference to a particular signal, describes a value that represents a desired fluid flow.
Each of the components of MFC 200 has an associated gain, which gains can be combined to determine a system gain. In block 240 , a reciprocal gain term G is formed by taking the reciprocal of a system gain term and applying it as one of the inputs to the GLL controller. It should be appreciated that the reciprocal gain term may be the reciprocal of all or fewer than all of the gain terms associated with the various components around the control loop of the mass flow controller. For example, improvements in control and stability may be achieved by forming the reciprocal of the product of the individual component gain terms. However, in preferred embodiments, gain term G is formed such that the loop gain remains a constant (i.e., gain G is the reciprocal of the system gain term).
Pressure sensed at the inlet 208 or elsewhere provides a pressure signal 290 to flow meter 210 to compensate for spurious indications due to pressure transients. Further, the pressure signal may be used by GLL controller 250 for feed forward control of the valve. Also, the pressure signal may be used to adjust the gain in a GLL controller.
Based in part on the flow signal and the set point signal SI 2 , the GLL controller 250 provides a drive signal DS to the valve actuator 260 that controls the valve 270 . The valve 270 is typically positioned downstream from the flow meter 210 and permits a certain mass flow rate depending, at least in part, upon the displacement of a controlled portion of the valve 270 . The controlled portion of the valve 270 may be a moveable plunger placed across a cross-section of the flow path 203 . The valve 270 controls the flow rate in the fluid path by increasing or decreasing the area of an opening in the cross section where fluid is permitted to flow. Typically, mass flow rate is controlled by mechanically displacing the controlled portion of the valve by a desired amount. The term displacement is used generally to describe the variable of a valve on which mass flow rate is, at least in part, dependent. As such, the area of the opening in the cross section is related to the displacement of the controlled portion, referred to generally as valve displacement.
The displacement of the valve is often controlled by a valve actuator, such as a solenoid actuator, a piezoelectric actuator, a stepper actuator etc. In FIG. 2 , valve actuator 260 is a solenoid type actuator; however, the present invention is not so limited, as other alternative types of valve actuators may be used. The valve actuator 260 receives drive signal DS from the controller and converts the signal DS into a mechanical displacement of the controlled portion of the valve. Ideally, valve displacement is purely a function of the drive signal. However, in practice, there may be other variables that affect the position of the controlled portion of the valve.
When the input pressure changes, for a brief period of time the sensor output does not accurately indicate the mass flow. To mitigate this effect, some mass flow controllers include a pressure transducer. Pressure transducers allow tuning of the dynamic response of the device as a function of pressure, which in turn can provide a faster response, especially at low inlet pressures. For example, U.S. Pat. No. 7,273,063 to Lull et al., which is commonly owned with the present application and which is hereby incorporated by reference, uses signals from a pressure transducer to modify the sensor signal to compensate for some pressure related transient effects and provides some compensation for changes in the amount of gas in the inventory volume.
There is some unavoidable internal volume between the flow meter and the control valve. That volume, referred to as an “inventory volume,” (e.g. 140 of FIG. 1 , and 280 of FIG. 2 ) contains a small amount of gas that varies with pressure and temperature. An inventory volume exists between the flow meter and any downstream restriction, with the control valve being an example of a restriction. As the input pressure to the flow meter changes, a certain net amount of fluid flows into or out of the inventory volume to equalize the inventory volume pressure with that of the rest of the system, thus changing the amount, that is the mass, of fluid stored in that inventory volume. When input or output pressure changes, there is a net flow into or out of the inventory volume, and this leads to a discrepancy between the flow through the flow meter and the flow actually delivered to the process. U.S. Pat. No. 7,273,063 compensates for this by simply differentiating the inlet pressure and subsequently applying a filter, for example, to generate a transient compensating signal that nominally matches that spike for the signal inside the flow meter. The transient compensating signal is subtracted from the signal from the flow meter to compensate for the pressure change. The technique of U.S. Pat. No. 7,273,063 provides accurate sensor output for some gases, but does not provide sufficiently accurate signals for other gases.
While the presence of the inventory volume is known and attempts have been made to compensate for the volume to properly indicate flow, present methods are insufficiently accurate for the increasingly demanding standards of industry.
SUMMARY OF THE INVENTION
An object of the invention is to provide improved accuracy in flow sensors and flow controllers.
The present invention provides a more accurate indication of gas flow through a flow controller by accounting for the compressibility of the gas when correcting a flow signal for inaccuracies caused by changes in pressure.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. For example, both pressure and temperature are required for calculations of the preferred embodiments. The pressure measurement used can be obtained, for instance, directly from inlet pressure, from a transducer exposed directly to the inventory volume, or approximated. Similarly, the temperature measurement used can be obtained, for instance, from the flow sensor body temperature or average gas temperature in the inventory volume. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more through understanding of the present invention, and advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
FIG. 1 illustrates a conventional thermal mass flow controller;
FIG. 2 illustrates a schematic block diagram of a mass flow;
FIG. 3 is a flow chart showing one preferred method of the present invention.
FIG. 4 is a chart illustrating normalized outputs of the stages of a preferred signal filter of the present invention.
FIG. 5 is a chart illustrating the scaled filter section outputs of FIG. 4 and the resulting sum for a preferred embodiment of the present invention.
FIG. 6 illustrates an algorithm of a preferred embodiment of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
While the mass flow controller described in U.S. Pat. No. 7,273,063 adequately compensates the sensor readings for pressure transients for some applications, it suffers from three significant shortcoming:
1. It does not adequately account for gas compressibility;
2. It does not adequately deal with nonlinearities in the flow meter; and
3. It does not adequately compensate for changes in flow meter dynamic response on different gasses or at different flow rates.
When the input pressure to an MFC changes the flow meter provides an inaccurate flow signal that does not correspond to the actual flow of gas through the valve and to the process tool. A portion of the inaccurate signal corresponds to the actual amount of gas that flows into or out of the inventory volume; another portion of the inaccurate signal is caused by the dynamic response of the flow meter to the transient changes in the gas flow through the meter as the pressure changes. Thus, an accurate correction not only compensates for the gas flowing into or out of the inventory volume, but also for the inaccuracy of the flow sensor signal caused by the unsettled thermal environment in the flow sensor caused by the change in flow. While the actual flow into or out of inventory volume is thought to occur relatively quickly, on the order of a millisecond, the portion of the inaccurate signal caused by the dynamic response of the meter is thought to last longer, on the order of a second, which, if not corrected, can lead to a significant distortion of the measured flow.
Preferred embodiments correct for this transient response to changes in pressure causing net flow into or out of the inventory volume, so that a more accurate flow is reported to the control system of a mass flow controller to adjust the valve position and is reported to the process tool operator. Preferred embodiments of the present invention compensate for the inventory space by properly accounting for gas compressibility, non-linearities in the flow meter, and changes in flow meter dynamic response on different gasses and at different flow rates.
Embodiments of the invention substantially improve flow measurement accuracy, particularly on non-ideal gases, such as SF 6 , and on highly non-linear flow meters, by substantially improving pressure-transient performance compared to prior art mass flow controllers. Accounting for the compressibility significantly improves the measurement accuracy for gases that do not follow the ideal gas law (PV=nRT).
FIG. 3 shows an overview of the steps of a preferred embodiment of the present invention. Several of the steps are explained later in more detail. In step 302 , the system verifies that pressure information is available. If no pressure information is available, for example, because the pressure transducer is not providing a pressure signal input to the flow meter, then pressure effects on gas in the inventory volume cannot be calculated and the process ends at block 304 . The cause of the lack of pressure information is preferably investigated by an operator and corrected before the process restarts.
If pressure information is available, the compressibility of the fluid is determined in step 306 . The compressibility depends on the gas species and the pressure and the temperature of the gas. In step 308 , the system determines whether it is in an operating state in which inventory gas compensation is required. For example, if the operator sets the valve to stop the gas flow, then the gas flow rate through the valve is known to be zero, and so no adjustment to the sensor output is required to indicate an accurate flow rate. If no inventory gas compensation is required, the process stops in step 310 .
If inventory gas compensation is required, the process continues in step 312 , in which a value related to gas-in-inventory is calculated. As described above, there is a difference between the flow indicated by the flow sensor and the actual flow through the valve if, after passing through the flow sensor, there is a net gain or loss of gas in the inventory volume. Thus, the inventory volume compensation depends not on the actual amount of gas in the inventory volume itself, but on the change of the amount of gas in the inventory volume. If the amount of gas in the inventory volume remained constant, then no compensation for the inventory volume would be required. It is therefore not necessary to actually calculate the exact amount of gas in the inventory volume, it is only necessary to determine the change in the amount of gas. The change can be determined from a value related to the amount gas in the inventory volume, without calculating the actual amount of the gas in the inventory volume. For example, an inventory value that is proportional to the inventory amount can be calculated.
In step 314 , a value proportional to the derivative with respect to time of gas-in-inventory is calculated from the inventory values determined in step 312 .
In step 316 , the value proportional to the derivative determined in step 314 is applied to a signal filter to produce a signal corresponding to the inaccurate flow signal produced by the flow sensor in response to an input pressure change. Because the input to the filter is the value related to the time related change of gas amount in the inventory volume determined in step 314 , the signal produced by the filter will depend on the variables used to produce the derivative, that is, the compressibility of the gas, the change in pressure, and the temperature of the gas. Thus, the signal from the filter can more accurately reflect the actual operating conditions of the flow meter.
In step 318 , a gain factor, specific for the process gas being used in the MFC, is applied to the signal calculated in step 316 to produce a compensation signal that matches the magnitude of the inaccurate flow signal from the flow meter on the actual process gas. In step 320 , the compensation signal is subtracted from the output of the sensor, which eliminates the effects of changes in inventory value from the flow signal so that the flow meter is more accurately indicating the actual fluid flow to a process tool.
Below are described in more detail several exemplary methods of carrying out some of the steps of FIG. 3 . The invention is not limited to these exemplary methods. For determining the compressibility of the gas in step 306 , various algorithms are known. Some calculations of compressibility are very accurate over a wide range of pressure and temperature, but are not well suited for implementation directly in the device firmware. A preferred algorithm is sufficiently accurate to provide flow information at the required accuracy, while requiring relatively little processing and little data storage. One algorithm expresses the compressibility, Z(P,T), as a function of pressure and temperature using the alternate form of the well known virial expansion, which expresses the pressure of a many-particle system in equilibrium as a power series in the pressure. A suitable implementation truncates the power series at the second order term.
Z ( P,T )=1+ B ′( T )* P+C ′( T )* P^ 2 [Equation.1]
where:
P is the absolute pressure of the gas in the inventory volume, for computational convenience P may be expressed as a fraction of the full scale range of the absolute pressure signal available to the flow meter (P^2=P*P is the notation for the second order term). B′ and C′ are the alternate form of the second and third virial coefficients. T is the absolute temperature of the gas in the inventory volume, expressed in degrees Kelvin (K).
The alternate form of the 2nd & 3rd virial coefficients can each be approximated over a reasonable temperature range as cubic polynomials of 1/T:
B ′( T )˜ B ( T )= B 0+ B 1/ T+B 2/ T^ 2+ B 3/ T^ 3
C ′( T )˜ C ( T )= C 0+ C 1/ T+C 2/ T^ 2+ C 3/ T^ 3
Values of Z(P,T) may be obtained spanning the range of operating pressures and temperatures anticipated for the flow meter. The Z(P,T) values may come from measurement data or may be computed using a suitable equation of state model. One suitable model for computing Z(P,T) is that of Lee and Kesler using the three-parameter principle of corresponding states of Pitzer. For a particular temperature Ti the values of Z(P,Ti) at several different pressures (e.g. P 1 , P 2 , P 3 , . . . , Pn) form a curve that may be fit by suitable mathematical process to determine B′(Ti) and C′(Ti) satisfying Equation.1 at temperature Ti over the pressure range P 1 -Pn. The values of B′(T) and C′(T) may be thus determined at several different temperatures (e.g. T 1 , T 2 , T 3 , . . . , Tn). The temperature related sequence of values B′(T 1 ), B′(T 2 ), B′(T 3 ), . . . , B′(Tn) form a curve that may be fit by a suitable mathematical process to determine the approximation B(T). Similarly the temperature related sequence of values C′(T 1 ), C′(T 2 ), C′(T 3 ), . . . , C′(Tn) form a curve that may be fit by a suitable mathematical process to determine the approximation C(T). Least squares fitting is one example of a suitable mathematical process for determining B(T) and C(T) as cubic polynomials of 1/T. A preferred algorithm then uses the compressibility approximation:
Za ( P,T )=1+( B 0+ B 1/ T+B 2/ T^ 2+ B 3/ T^ 3)* P +( C 0+ C 1/ T+C 2/ T^ 2+ C 3/ T^ 3)* P^ 2 [Equation.2]
To determine a value related to the gas in inventory for step 312 , one can first determine an expression for the actual amount gas in inventory, and then derive a simpler expression proportional to the gas in inventory, the simpler expression being used by firmware during operation of the MFC. The actual amount of gas in inventory does not need to be calculated. The gas-in-inventory can be calculated as:
Ig
=
Vi
Z
(
P
,
T
)
·
P
P
0
·
T
0
T
[
Equation
.
3
]
where:
Ig=gas stored in the inventory volume (standard cm 3 )
Vi=Inventory volume (cm 3 )
P=Pressure of the gas in the inventory volume (Pa)
P 0 =standard pressure (Pa)
T=Temperature of the gas in the inventory volume (K)
T 0 =standard temperature (K); and
Z(P,T)=Compressibility of the process gas at pressure P and temperature T (per Equation.1 above).
As it well known, 1 standard cm 3 =1/22414 mole
Because the process requires only an expression proportional to the gas in inventory, the constant terms Vi, P 0 , and T 0 can therefore be omitted and the remaining expression will still represent a value, Mg, proportional to gas-in-inventory, leaving:
Mg =( P/ ( Za ( P,T )* T ) [Equation.4]
where:
Za(P,T)=approximated compressibility of the process gas at pressure P and temperature T (per Equation.2 above);
While the value of Mg above is an example of a value proportional to the gas in inventory that can be used in a preferred algorithm, the invention is not limited to any particular value calculation.
In step 314 , a value proportion to the change in time of the amount of gas in the inventory volume is determined. The values of Mg can be calculated repeatedly as data from the pressure and temperature sensors are updated. The values of Mg thus form a time series of discrete values, equally spaced in time by a period τ and designated . . . , Mg n−1 , Mg n , Mg n+1 , . . . , the derivative of Mg with respect to time can be approximated over the interval between samples n−1 and n as simply:
ⅆ
Mg
n
ⅆ
t
=
Mg
n
-
Mg
n
-
1
τ
[
Equation
.
5
]
Since the system requires only a value proportional to the derivative of the amount of gas in inventory over time, and not the derivative itself, and because τ is fixed for any given device, the system omits the constant τ from the calculation and uses the quantity Mg n −Mg n−1 as a value proportional to the derivative. The subscripts n and n−1 represent the value of the corresponding variables for the current and previous signal processing cycles, respectively.
In step 316 , the value proportional to the derivative is filtered to produce a signal matching the dynamics of the inaccurate flow signal. The change in Mg in response to a step change in pressure is dictated by the acoustic propagation delay and pneumatic RC time constant of the flow meter and inventory volume. Since flow meters generally have a very low flow resistance, and the inventory volume is minimized as much as possible in the design of the MFC, the pneumatic time constant is typically very short. Since the bypass is generally physically short and relatively open, the acoustic propagation delay is short as well, typically less than a millisecond.
Flow meter response, however, is far slower. Flow meter dynamic response is dominated by multiple thermal time constants in the flow sensor itself—some of which are on the order of a second. Prior art flow meters response is typically compensated to settle in a fraction of a second, but this still leaves a significant discrepancy between the actual flow into or out of the inventory volume and the corresponding spike in indicated flow.
To more accurately indicate flow, the system of the present invention produces a compensation signal closely matching the waveform of the pressure transient induced “inaccurate flow” signal from the flow meter. The compensation signal is derived from the actual flow into or out of the inventory volume. This compensation signal could be produced through a wide variety of signal filters. While one preferred filter is described below, the invention is not limited to any particular filter, and skilled persons can readily determine other filters that can accomplish this task.
One suitable filter comprises a cascade of six, two-pole infinite impulse response, low-pass filter sections to produce a series of six “smeared out” pulses from an impulse input. These “smeared out” pulses are then scaled and summed to produce a waveform to compensate for the inaccurate sensor signal.
Each filter section implements the equation:
J m,n =2* J m,n−1 −J m,n−2 +(( I m,n −J m,n−1 )* Q m −( J m,n−1 −J m,n−2 ))* P m
where:
I m,n is the input to filter section m on signal processing cycle n
J m,n is the output of filter section m on signal processing cycle n
P m and Q m are tuning parameters controlling the impulse response of filter section m. The parameters P m and Q m are determined empirically as described below.
The input, I 1,n , to the first filter section is the value related to the change in inventory volume calculated in step 312 , that is, Mg n −Mg n−1 . For the second and subsequent cascaded filter sections, the input I is the output from the previous section, that is, I m,n =J m−1,n . FIG. 4 shows the outputs of each filter section in the cascade for a unit impulse in to the cascade, for typical values of P and Q. Each output in the figure is normalized to a peak value of 1 for easy visibility. The filter described produces a waveform that closely matches the shape of the inaccurate flow signal, but at some arbitrary magnitude. This signal must then be scaled to match the actual magnitude of the inaccurate flow signal on a specific device. Lines 401 - 406 represent respectively, the output of the filter stages one through six.
Each of the filter section outputs is scaled by a gain factor G m and summed to get a simulated inaccurate flow signal for each time interval n for the specific process gas being used.
Simulated
False
Signal
n
=
∑
m
=
1
6
G
m
·
J
m
,
n
FIG. 5 shows the scaled filter section outputs (Gm*Jm,n) and the resulting sum for a typical application. Lines 501 - 506 represent respectively, the scaled output of the filter stages one through six.
This scaling must take into account several factors:
The inventory volume varies from device to device. The magnitude of the filter output varies depending on the inventory volume and the fitting procedure used to select the specific set of G values to be used. The range of the flow meter varies from device to device, and from process gas to process gas on a specific device.
All of the required parameters—P m , Q m , and G m —can be determined during production of the flow meter comprised of a sensor and a bypass by a procedure that includes changing the input pressure to the flow meter by a representative amount at a representative rate and then observing the sensor electrical output and measuring the actual flow. The discrepancy between the actual measured fluid flow and the sensor output represents the “false flow.” Software optimizes the filter parameters to give a waveform closely matching the shape of the measured inaccurate flow signal, and matching its amplitude expressed in sccm, or standard cm 3 per minute.
The P and Q values can be selected by an N-dimensional nonlinear minimizer, using for each trial G values obtained by a linear least squares fit
If sensor response and response compensation are sufficiently reproducible, then nominal P, Q, and G values can be determined for a typical sensor through testing with very fast pressure transients on a few sample sensors and the average values applied across some larger population.
Note that the specific G values used are somewhat arbitrary, though their relative values are critical to the filter performance. The entire waveform may be scaled up or down, adjusting all G values by the same factor in order to match their magnitudes to that of a specific flow meter. In some embodiments, a single scale factor is applied in step 318 to the filter output, in addition to the individual scale factors applied to each filter section.
The gain factor applied in step 318 is inversely proportional to the nominal flow range of the device on a specific process gas, expressed in sccm. This proportionality constant is required because the flow rate, at the point where the compensation signal is injected, is expressed as a fraction of the nominal flow range of the device on the selected process gas. If the flow signal were expressed directly in sccm, no gain adjustment would be needed. This is because the filter input is directly proportional to the net flow rate (in sccm) into or out of the inventory volume—completely independent of gas species—so long as the compressibility calculation and measured temperature and pressure are correct.
If the filter parameters for the inventory volume compensation are determined at the factory before the sensor is calibrated, the indicated flow signal during the inventory volume compensation correction will be incorrect by an amount dependent on the flow rate, and the gain factor needs to compensate for this error. The gain factor can be determined empirically, or from the non-linearity of the sensor and the maximum net flow into or out of the inventory volume.
In other embodiments, it may be desirable to record the compensation transient data at a point where it is convenient in terms of the manufacturing process, and then convert the data to a calibrated flow signal and perform the curve fit and gain adjustment after final calibration. Skilled person can determine a gain constant based on an understanding of a particular flow sensor device and a particular production process flow.
In some embodiments, the inventory volume correction can be confined to flow rates where the flow meter is essentially linear, and then the software could scale based on the difference between the estimated low-flow slope of the calibration curve (during the compensation process) and the final low-flow slope of the calibration curve once a valid curve is determined.
Note that while the filter parameters are preferably determined at the factory and fixed for the sensor, the gain adjustment is determined during operation because it is proportional to the fluid flow.
The algorithm used for the compensation for the inventory volume is typically stored in firmware on the circuit board of the mass flow controller. Depending on the processing power available in the specific application, the inventory volume compensation filter cascade can be run at less than the full signal processing rate, with a portion of the filter being run on each processing cycle.
The algorithm described above compensates for the linearized flow signal rather than the raw sensor output. Skilled persons could readily create algorithms to operate on the raw flow signal. When correcting the linearized flow signal, either the final inventory gas compensation gain adjustment must be made after the device is calibrated for a particular gas, or the calibration process must provide a calibration to convert sensor output to determine the inventory gas compensation gain adjustment for the particular gas used. This is because the parameters used in the filter, P, Q, and G, will vary with the gas used. If the gas used in the process is different from the gas used to determine the filter parameters, then the sensor output will need to be compensated for the different gas. This can be done either by performing calibration on every unit with nitrogen and using known methods of adjusting for the process gas, or by performing a final inventory gas compensation gain adjustment as part of a calibration process using the process gas or suitable surrogate gas. The correction signal should coincide temporally with the sensor output signal being corrected. Due to relatively long time constants associated with heat diffusion in the mechanical structures of a heated capillary flow sensor there is typically some delay between detection of a change in pressure and the output of the false signal from the flow meter. The delay inherent in the signal processing, particularly in the multistage filter, may be adequate to temporally coordinate the correction signal with the sensor false signal; if not, an additional delay element may be added to the circuit.
Also, since the algorithm above is compensating the linearized flow signal, the result will be sensitive to any discrepancy between the derivative of the linearization curve and the derivative of the actual flow meter output-versus-flow curve. Such nonlinearities would most often arise at low flow rates due to uncorrected sensor offsets during final calibration, such as residual valve heating effects, potentially leading to a low-flow “hook” in the derivative of the linearization curve. Such irregularities can degrade accuracy of the inventory gas compensation algorithm, and should be avoided in most embodiments.
Because temperature changes relatively slowly, calculation of temperature dependent virial coefficients can be scheduled at the convenience of the firmware. They are preferably updated at least 10 times per second, but updating them more often than the temperature is updated is not useful. Calculation of flow compensation is preferably performed as part of normal flow meter processing on every signal processing cycle, and should occur as soon as the linearized flow rate becomes available.
All other firmware calculations defined above, such as the compressibility, the value corresponding to the inventory value, the value corresponding to the amount of gas in the inventory volume, the value corresponding to the derivative of the amount of gas in the inventory volume, and the compensation signal are preferably preformed on every signal processing cycle. These calculations can begin as soon as the normalized flow rate calculation is available, and are preferably completed before the drive signal to the valve actuator is produced.
Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. For example, while the embodiment described above compensates for input pressure transients, skilled persons can recognize that embodiments could also compensate for changes in output pressure in the case of devices wherein the flow meter is not substantially isolated from the output pressure by action of the control valve (e.g. in a reverse flow device having the control valve upstream of the flow meter). Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. For example, both pressure and temperature are required for calculations of the preferred embodiments. The pressure measurement used can be obtained, for instance, directly from inlet pressure, from a transducer exposed directly to the inventory volume, or approximated. Similarly, the temperature measurement used can be obtained, for instance, from the flow sensor body temperature or average gas temperature in the inventory volume. The invention is not limited to any particular means for generating an electrical signal corresponding to the flow. While an embodiment using two resistive coils is described, other embodiments can use three or any number of resistive coils, or other temperature sensitive elements, such as thermocouples or thin film resistors. Also, the invention is not limited to mass flow meters, but could be applied to other types of flow meters, such as volume flow meters.
While the inventory volume was described in the embodiment above as comprising the volume between the flow sensor and the adjustable valve, the inventory volume could comprise any volume between the flow sensor and a flow restriction, such as an orifice. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
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A system and method of compensating for pressure variations in a flow controller entails the use of the compressibility of the gas being controlled to provide a more accurate measurement of the flow.
| 6
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BACKGROUND OF THE INVENTION
The present invention pertains to a device generally referred to in the art as a tube connector. This device is utilized to connect thin wall conduit, tubes, or the like, such as found in refrigeration apparatus, to high-pressure test equipment for testing of the apparatus before it is put into service. In the pretesting of such equipment on an assembly-line basis or where equipment is already installed, it is necessary to be able to connect the equipment to the testing apparatus quickly and easily. Numerous devices of this general type exist in the prior art, as set forth in the following U.S. Pat. Nos.: 2,819,733, 3,542,076, 3,727,952, 3,738,688, 3,779,587, 3,799,207, 3,868,132, 4,326,407, and 4,540,201.
One problem, however, which has existed in devices of the type illustrated in Racine Patent 3,868,132 is that when the tube is inserted and the handle is rotated to the locked position and the tube is then pressurized, the pressure acting against the side face of the seal urges it away from the face of the piston thereby promulgating a leak path for pressure to escape along the seal face and then between the piston and housing. No prior art device has effectively resolved this problem.
SUMMARY OF THE INVENTION
The present invention provides a tube connector which defines a chamber in one end of a cam-operated piston, which chamber is adapted to receive and confine a seal therein during the operative pressure testing of the equipment. This arrangement increases sealing effectiveness upon pressurization of the tube and decreases pressure loss.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view, partially in section, of the tube connector of the present invention in a nonoperative position.
FIG. 2 is a top view of the device illustrated in FIG. 1, also in the non-operative position.
FIG. 3 is a side view, partially in section, of the tube connector of the present invention in an operative position.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIGS. 1 and 2 illustrate the tube connector of the present invention, generally referred to as 10, in a non-operative or at-rest position. The tube connector includes a hollow body 11 with an enlarged entrance aperture 12 defined at one end. A narrower entrance aperture 13 is defined in the hollow body 11 concentric with the aperture 12. An automatic tube-locking mechanism 15 is provided intermediate the apertures 12 and 13 to securely grip and hold a tube in place. The tube locking device or gripping mechanism includes a lever 16 secured to the housing 11 by pivot pin 17. A tapered aperture 18 is defined through a portion of the handle 16 intermediate the apertures 12 and 13. The tapered aperture 18 includes a knife edge 20, best shown in FIG. 1. A spring 21 is shown disposed between the handle 16 and the housing 11 in a manner so as to urge the lever to pivot about the pivot pin 17 in a clockwise direction until a corner 22 of the lever 16 engages the front face of the housing 11, thereby limiting any further travel of the lever 16. When the lever 16 is in the at-rest position, shown in FIG. 1, the central axis of the aperture 18 is not aligned with the central axis of aperture 13, but rather is disposed at an angle thereto.
The housing 11 defines a cylinder 23 internal thereto. Slidably disposed within the cylinder 23 is a piston 25, which defines a passage 26 through its interior. The piston 25 further defines a recess 27 within which is disposed a resilient biasing member, here illustrated as a spring 28. The spring 28 is retained in a compressed condition within the confines of the recess 27 by any of a number of commonly accepted methods including providing a lip (not shown) at the outer edge of the recess. The chamber 27 is sized so as to receive a tube to be tested. The piston 25 defines a chamber 30 at one end which is particularly adapted to receive and confine a compressible seal 31 formed of resilient elastomeric material. The seal 31 is sized so as to permit the insertion of a tube through its central aperture 32.
A cam locking lever 35, best illustrated in FIG. 2, is used to lock a tube in place when testing is desired. The cam lever includes a handle 36 of generally U-shaped, hollow configuration so as to overlie the end of the piston 25 when in the closed position, as illustrated in FIG. 3. The cam lever 35 is pivotally secured to the housing 11 by means of screws 37 and 38 which terminate in pivot pins 40 and 41, which are inserted through apertures 42 and 43 formed in the cam lever. The lever 35 further includes a rounded cam surface 45, best shown in FIG. 2, the purpose for which will readily become apparent. Disposed adjacent the cam surface 45 is a metallic washer 46. As shown in FIG. 1, the washer 46 lies between the surface 45 and a shoulder 47 formed on a rear face of the piston 25.
The operation of the invention of the present device is as follows. When the device is in the nonoperable position, as shown in FIGS. 1 and 2, the locking lever 16 is biased toward its clockwise position with the edge 22 of the lever engaging the housing. The aperture 18 is out of alignment with the entrance aperture 13. The cam lever 35 is raised and the piston 25 is disposed toward the right, as shown in FIG. 1. A substantial gap exists between the left end of the piston 25 and the inner face of the housing 11. The seal 31 is substantially uncompressed and resides partly within the chamber 30.
When testing is desired, a tube 50 which is connected to the device to be tested is inserted through apertures 12, 18, 13, and 32 into the recess 27 defined within the piston. In order to accomplish this, the gripping mechanism 15 is actuated so as to align apertures 18 and 13 concentrically. This is easily done by gripping the end of lever 16 and pressing toward the housing 11, thereby rotating the handle 16 about the pivot point 17 in a counterclockwise direction. When the apertures 18 and 13 are aligned, tube 50, as illustrated in FIG. 3, is inserted through apertures 18 and 13, through the inner periphery 32 of the seal 31 until the tube engages spring 28 and lies partially within the recess 27. The lever 16 is then released, and the spring 21 causes the lever to pivot about point 17, clockwise, until the knife edge 20 engages the tube 50. The gripping mechanism 15 thus secures the tube in place. A fluid path 51 is defined between the outer wall of the tube 50 and the inner wall of the recess 27 of sufficient dimension so as to allow fluid pressure to be communicated from the tube 50 through path 51 and to act against end face 52 of seal 31.
When the cam lever 35 is rotated clockwise from the position shown in FIG. 2 to the position shown in FIG. 3, the cam surface 45 acts upon the metal washer 46 forcing the piston 25 to the left from the position shown in FIG. 1 to assume the position shown in FIG. 3. The gap between the end face of the piston 25 and the front face of the housing 11 is substantially diminished. The seal 31 is now substantially confined between the chamber 30, on its outer periphery, and the outer diameter of the tube 50, on its inner periphery.
When it is desired to conduct the pressure test, a source of fluid pressure, not illustrated, is connected to the end of the piston 25 so as to allow pressure to be communicated through passage 26 to conduit 50. When the charging fluid is introduced, fluid pressure passes through the fluid path 51 and acts against the side face 52 of the seal 31 exerting a force against the seal tending to further compress same. By virtue of the confinement of the seal within chamber 30, the effect of the pressure acting against the seal face is to further compress the seal and to force a tighter engagement of the interior surface 32 of the seal 31 with the outer periphery of the tube 50, thereby increasing the sealing effectiveness of the tube connector. Such action increases the efficiency of the sealing action and minimizes the possibility of pressure escaping around the seal 31, thereby resulting in a tube connector which provides greatly enhanced results over prior art devices.
Various features of the invention have been particularly shown and described in connection with the illustrated embodiments of the invention, however, it must be understood that these particular arrangements merely illustrate and that the invention is to be given its fullest interpretation within the terms of the appended claims.
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A tube connector used to connect conduits for fluid pressure to pressure testing equipment, the tube connector including a piston slidably disposed within a housing, the piston defining a chamber for containment of a seal which engages the outer periphery of the tube to be tested.
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This is a continuation of application Ser. No. 861,088, filed Dec. 15, 1977, now abandoned.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an improved thermoplastic polyurethane and to a process for the preparation thereof. More particularly, this invention is concerned with a thermoplastic polyurethane suitable for producing artificial leathers having improved properties such as moderate elasticity, resistance to microorganisms, cold, stickiness and nitrogen oxide gas, and with a process for producing the same.
2. Description of the Prior Art
Heretofore, artificial leathers consisting mainly of a non-woven, woven or knitted fabric and an elastic polymer have been made as a substitute for natural leather. The mechanical and physical properties, as well as the practical durability, of these artificial leathers depend upon not only the kind(s) of fibers comprising the fabric, the structure of the non-woven fabric and the physical properties of the woven or knitted fabric, but also depend greatly upon the properties of the elastic polymer.
In order to make an artificial leather having various desirable properties, therefore, it is necessary to use an appropriate elastic polymer.
As one such elastic polymer, polyurethanes have been used which consist of a soft segment of a long-chain diol such as a polyester diol or a polyether diol, and a hard segment derived from a low-molecular-weight diol such as ethylene glycol, propylene glycol or 1,4-butanediol, or a diamine such as ethylene diamine or 1,2-propylene diamine, and an organic diisocyanate.
Such polyurethanes have excellent flexibility, bending durability, abrasion resistance, toughness and resistance to chemicals, and hence are widely used for artificial leathers. These polyurethanes, however, have disadvantages:
(1) Since these polyurethanes have too high elasticity, an artificial leather prepared using these polyurethanes has an elasticity similar to rubber, and does not exhibit a natural leather touch.
(2) Since the resistance to microorganisms of these polyurethanes is poor, the durability of an article obtained using these polyurethanes is not good enough to provide an article suitable for practical use. For example, the surface of shoes prepared therefrom will crack when worn for a long time.
(3) Since these polyurethanes have high stickiness and a high frictional coefficient, the touch or feel of an artificial leather obtained therefrom is not good when they are used as a surface finishing polymer for an artificial leather.
(4) These polyurethanes have poor resistance to cold and tend to be yellowed by a gas such as nitrogen oxide gas.
As described above, these known polyurethanes which consist of a soft segment of a long-chain diol and a hard segment derived from a low-molecular-weight diol or a diamine and an organic diisocyanate are not necessarily suitable for artificial leathers. Methods have been proposed to avoid the disadvantages of these known polyurethanes, which methods comprise adding a third component to such known polyurethanes to improve the basic properties of these polyurethanes.
Japanese Patent Application Laid-Open No. 51533/75, Morita et al, published May 8, 1975, discloses a polyurethane composition having improved stickiness which contains a polar, organic fluorine compound.
Japanese Patent Application Publication No. 22053/75, Shirota et al, published July 28, 1975, discloses a polyurethane composition having improved stickiness which contains isophthalic acid or terephthalic acid components in the polyurethane molecule, which can be used for preparing an artificial leather having a good feel. However, these polyurethane compositions do not have other good properties such as moderate elasticity or resistance to microorganisms, cold, and nitrogen oxide gas which are necessary in polyurethanes used to prepare excellent artificial leathers.
U.S. Pat. No. 3,681,291, Khan, issued August 1, 1972, discloses a liquid castable urethane composition consisting of the reaction product of: (I) a prepolymer obtained by reacting a diisocyanate with a polyol such as polyoxypropylene polyol with (II) a curing composition comprising (a) a polyol such as polyoxypropylene polyol, (b) an aromatic diol such as an adduct of bisphenol A and propylene oxide, (c) an aromatic amine corresponding to the formula ##STR5## wherein n represents a value between 0.1 and 0.3 and (d) an organometallic catalyst. Since this urethane composition contains an aromatic amine having more than two active hydrogens as a curing agent, the polyurethane obtained has a very high molecular weight and high strength, and is insoluble in organic solvents. Although this polyurethane is suitable for motor mounts, vibration dampers, oil seals, gaskets, fuel hose and machine pads, it is not useful for artificial leathers.
SUMMARY OF THE INVENTION
It has now been found that if a derivative of an aromatic diol, such as biphenol A, or an alicyclic diol, such as bis(4-hydroxycyclohexyl)methane, or a derivative of an alicyclic diol is used as a third component in the process for the preparation of the above described polyurethanes which consist of a soft segment of a long-chain diol and a hard segment derived from a low-molecular-weight diol or a diamine and an organic diisocyanate, the above-mentioned disadvantage of the prior art can be substantially overcome.
It is, therefore, one object of the present invention to provide a thermoplastic polyurethane suitable for producing artificial leathers having improved properties such as moderate elasticity and resistance to microorganisms, cold, stickiness and nitrogen oxide gas.
It is another object of the present invention to provide a process for the preparation of the above thermoplastic polyurethane.
The above-mentioned objects are attained by the thermoplastic polyurethane in accordance with the present invention, which comprises the polymerization product of:
(A) a long-chain diol having a molecular weight of from about 800 to about 4,000;
(B) a difunctional active hydrogen-containing chain-extender having a molecular weight of from about 50 to about 150;
(C) an organic diisocyanate, and
(D) a diol compound represented by the following formula (I): ##STR6## wherein R 1 and R 2 may be the same or different and are hydrogen or an alkyl radical having from 1 to 3 carbon atoms, R 3 and R 4 may be the same or different and are an alkylene radical having from 2 to 4 carbon atoms, Y is a bivalent radical selected from the group consisting of ##STR7## wherein x is hydrogen, chlorine, bromine or a methyl radical, m and n are positive integers satisfying the formula 2≦m+n≦10 when Y is ##STR8## or m and n are zero or positive integers satisfying the formula 0≦m+n≦10 when Y is ##STR9## wherein component (D) comprises from about 3% to about 15% by weight of the polyurethane, and the nitrogen atoms derived from component (C) comprise from about 3% to about 6% by weight of the polyurethane.
The process for the preparation of the thermoplastic polyurethane is characterized by reacting the (A), (B), (C) and (D) components where the weight ratio of the (total of the (A), (B) and (C) components):((D) component) is from 97:3 to 85:15, wherein the amount of component (C) is such as to provide nitrogen atom content derived from component (C) of from about 3% to about 6% by weight of the polyurethane and wherein component (D) is such that the pH of an aqueous solution containing 1% by weight of the component (D) is from about 5.0 to about 7.5 at room temperature.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The diol compounds (compound (D)) employed in the present invention include: (1) adducts of aromatic diols and alkylene oxides satisfying the formula 2≦m+n≦10, (2) alicyclic diols (m+n=0) and (3) adducts of alicyclic diols and alkylene oxides satisfying the formula 1≦m+n≦10.
As aromatic diols, there can be exemplified bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl) propane(bisphenol A), 2,2-bis(4-hydroxyphenyl)butane, 3,3-bis(4-hydroxyphenyl)pentane, bis(4-hydroxy-3,5-dimethylphenyl)methane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)butane, 3,3-bis(4-hydroxy-3,5-dimethylphenyl)pentane, bis(4-hydroxy-3,5-dibromophenyl)methane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)butane and 3,3-bis(4-hydroxy-3,5-dibromophenyl)pentane.
As alicyclic diols, there can be exemplified bis(4-hydroxycyclohexyl)methane, 2,2-bis(4-hydroxycyclohexyl)propane and 3,3-bis(4-hydroxycyclohexyl)pentane.
As alkylene oxides, there can be exemplified ethylene oxide, propylene oxide and butylene oxide.
Among these diol compounds, the diol compounds represented by the following formula (II) are preferred: ##STR10## In formula (II), R 5 and R 6 are the same and are a member selected from the group consisting of --CH 2 .CH 2 -- and ##STR11## Z is a member selected from the group cosnsisting of ##STR12## k and l are 1 or 2 when Z is ##STR13## and k or l are 0, 1 or 2 when Z is ##STR14##
The diol compound (component (D)) in the present invention comprises from about 3% to about 15% by weight of the obtained polyurethane. When the amount of the diol compound is less than about 3% by weight, the obtained polyurethane does not have excellent properties such as moderate elasticity, resistance to microorganisms, cold, stickiness and nitrogen oxide gas. On the other hand, when the amount of the diol compound is more than about 15% by weight, the obtained polyurethane has too high an elastic modulus, and hence is not suitable for artificial leathers.
The long-chain diols having a molecular weight of from about 800 to about 4,000 include conventional polyester diols and polyether diols.
As useful polyester diols, there can be exemplified polyester glycols which are obtained by reacting an aliphatic dicarboxylic acid, such as succinic acid, adipic acid, sebacic acid and azelaic acid, or a lower alkyl (1-4 carbon atoms) ester of the aliphatic dicarboxylic acid, with an aliphatic glycol, such as ethylene glycol, 1,2-propylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, neopentyl glycol or a mixture thereof and polyester diols which are obtained by the ring-opening-polymerization of lactones such as ε-caprolactone. In the polyester diols of the present invention, a part (less than 20 mol %) of the aliphatic dicarboxylic acid may be replaced by an aromatic or alicyclic dicarboxylic acid.
As useful polyether diols, there can be exemplified polyalkyleneether glycols, such as polyethyleneether glycol, polypropyleneether glycol, polytetramethyleneether glycol and polyhexamethyleneether glycol; copolymerized polyether diols such as polyethylenepropyleneether glycol; and block copolymerized polyether diols such as polyethyleneether-polytetramethyleneether block copolymer.
In the present invention, it is possible to use any one of the above-mentioned long-chain diols or a mixture thereof. Nevertheless, a mixture of the long-chain diols is preferably used to obtain a polyurethane having special properties. When a mixture of from about 90% to about 30% by weight of one or more polyester diols and from about 10% to about 70% by weight of one or more polyether diols is used, in particular, it is possible to obtain a polyurethane having excellent resistance to microorganisms. When a long-chain diol containing more than about 70% by weight of one or more polyether diols is used, in particular, it is possible to obtain a polyurethane having excellent resistance to cold.
The organic diisocyanates used in the present invention include aliphatic, alicyclic and aromatic diisocyanates or mixtures thereof. Such diisocyanates include, for example, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, tolylene-2,4-diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, diphenylmethane-4,4'-diisocyanate, naphthalene-1,5-diisocyanate, diphenyl diisocyanate and p-xylylene diisocyanate.
Among these organic diisocyanates, diphenylmethane-4,4'-diisocyanate, p-phenylene diisocyanate, p-xylylene diisocyanate and a mixture thereof are preferred. Diphenylmethane-4,4'-diisocyanate is particularly preferred.
In the present invention, the amount of nitrogen atoms derived from the organic diisocyanate comprises from about 3% to about 6% by weight of the obtained polyurethane. When the amount of nitrogen atoms is less than about 3% by weight, the obtained polyurethane has too low an elastic modulus, and hence is not suitable for obtaining artificial leathers having leathery suppleness. On the other hand when the amount of nitrogen atom is more than about 6% by weight, the obtained polyurethane has too high an elastic modulus, and hence is not suitable for obtaining aritifical leathers having a leathery soft touch.
Especially, when the amount of nitrogen atoms comprises from 4.7% to about 6.0% by weight of the obtained polyurethane, the obtained polyurethane has excellent resistance to organic solvents and stickiness as well as a low frictional coefficient. These polyurethanes overcome various problems in the manufacturing process for artificial leathers, e.g., they are not subject to the disadvantage of foreign matter, such as fibrous waste, adhering to the surface of the artificial leather during surface finishing processing.
In the process invention, the difunctional active hydrogen-containing chain-extenders having a molecular weight of from about 50 to about 150 include diols, such as ethylene glycol, propylene glycol, 1,4-butane diol and 1,6-hexane diol; diamines, such as ethylene diamine, 1,2-propylene diamine, 1,4-butylene diamine, hexamethylene diamine, cyclohexane diamine and xylylene diamine; alkanol amines, such as ethanol amine and aminopropyl alcohol; hydrazine; and carbodihydrazides. Among these chain-extenders, diols are preferred because process control is easy.
The polyurethane of the present invention has a molecular weight of from about 30,000 to about 300,000, preferably from about 40,000 to about 100,000.
The polyurethane of the present invention may contain therein a coloring agent, such as carbon black, other pigments and dyestuffs, a thermal or light stabilizer, or an antioxidant.
The polyurethanes of the present invention, which have a tensile stress at 5% elongation of from 0.1 to 0.5 kg/mm 2 , a tensile stress at 20% elongation of from 0.2 to 1.0 kg/mm 2 and an elongation recovery at 50% elongation of from 50% to 87% at a temperature of 20° C., as measured in the form of a polyurethane film, are, in particular, suitable for producing a porous layer or a base layer of an artificial leather. The polyurethanes of the present invention, which have a tensile stress at 5% elongation of from 0.6 to 3.0 kg/mm 2 are, in particular, suitable for producing a surface finishing layer of an artificial leather.
The thermoplastic polyurethanes in the present invention are obtained by reacting: (A) a long-chain diol having a molecular weight of from about 800 to about 4,000; (B) a difunctional active hydrogen-containing chain-extender having a molecular weight of from about 50 to about 150; (C) an organic diisocyanate; and (D) a diol compound represented by the above formula (I), the pH of an aqueous solution containing 1% by weight of the diol compound being from about 5.0 to about 7.5 at room temperature, at a weight ratio of the total of the ((A), (B) and (C) components):(component (D)) being from 97((A)+(B)+(C)):3((D) to 85((A)+(B)+(C)):15((D)), and the amount of component (C) being such as to provide a nitrogen atom content derived from component (C) of from about 3% to about 6% by weight of the obtained polyurethane.
In the present invention, compound (D) has a quality of purity such that the pH of an aqueous solution containing 1% by weight of compound (D) is from about 5.0 to about 7.5 at room temperature (about 20° C.). The pH is measured as follows: A mixture of 1 g of compound (D) and 99 g of pure water is heated while stirring and boiled for 5 minutes, and is then cooled while stirring to room temperature (about 20° C.). After removing precipitated foreign matter from the obtained solution by filtration using filter paper, the pH of the filtrate is measured using a glass electrode in JIS-Z-8802-7 at room temperature.
By using compound (D) having a pH of from about 5.0 to about 7.5, a straight-chain polyurethane is dominantly obtained rather than a polyurethane having branched chains. When the pH of compound (D) is more than about 7.5, the obtained polyurethane tends to have too high a viscosity because of side reactions, and hence does not have good workability. When the pH of compound (D) is less than about 5.0, a polyurethane having a high molecular weight cannot be obtained because the rate of polymerization is lowered.
In the present invention, it is preferred to use compounds (A), (B) and (D) at a molar ratio of from about 1.5 to about 3.0 mols of compound (B) per 1 mol of the total of the compounds (A) and (D).
The preparation of the thermoplastic polyurethane in the present invention can be effected by any of the following methods.
(1) An one-shot method wherein a long-chain diol (component (A)), a chain-extender (component (B)) an organic diisocyanate (component (C)), and a diol compound (component (D)) are reacted at the same time.
(2) A two stage method wherein a prepolymer is formed by reacting a long-chain diol (component (A)) and a diol compound (component (D)) with an organic diisocyanate (component (C)), and thereafter the resulting prepolymer is reacted with a chain-extender (component (B)) to obtain a high-molecular weight polyurethane.
(3) A two stage metod wherein a prepolymer is formed by reacting a long-chain diol (component (A)) with an organic diisocyanate (component (C)), and thereafter the resulting prepolymer is reacted with a chain-extender (component (B)) and a diol compound (component (D)) to obtain a high-molecular-weight polyurethane.
Two stage methods (2) or (3) are preferred in the present invention, with two stage method (2) being especially preferred.
The above-described reaction can be effected by any of the following methods.
(1) A melt polymerization wherein the materials are reacted in a molten state.
(2) A solution polymerization wherein the materials are reacted in an organic solvent, such as dimethylformamide, dimethylacetamide and dimethyl sulfoxide.
(3) A slurry polymerization wherein the materials are reacted in a poor organic solvent for the polyurethane to obtain the polyurthane in a slurry state. (The method is disclosed in U.S. Pat. No. 3,895,134, Kigane et al, issued July 15, 1975.)
The slurry polymerization is preferred to obtain a polyurethane suitable for preparing a good microporous sheet for artificial leathers. The slurry of the polyurethane contains particles of polyurethane, and forms a good microporous polyurethane sheet when coagulated in a substrate of an artificial leather.
The organic solvent used in the slurry polymerization is preferably selected in accordance with the polyurethane compositions to prepare a desired polyurethane slurry. As useful organic solvents, there can be exemplified ketones, such as acetone, methyl ethyl ketone and methyl isobutyl ketone; esters, such as ethyl formate, ethyl acetate, butyl formate and butyl acetate; hydrocarbon halides, such as carbon tetrachloride, chloroform, dichloroethane and trichloroethane; aromatic hydrocarbons, such as benzene, toluene and xylene; and cyclic ethers, such as tetrahydrofuran and dioxane, all of which are poor solvents for the polyurethanes.
In the present invention, there can be also used a mixed solvent of any of the above-mentioned poor solvents and a good solvent for the polyurethane, such as dimethylformamide, dimethylacetamide, N-methyl pyrrolidone and dimethyl sulfoxide.
In order to obtain a polyurethane slurry having good workability and permeability in a substrate for forming a microporous smooth surface of an artificial leather, it is preferred that the size of the particles of the polyurethane in the polyurethane slurry be as small as possible. The average diameter of the articles preferably does not exceed about 30μ, and most preferably, does not exceed 20μ.
The amount of the particles of polyurethane is usually from about 10% to about 75%, preferably from 10% to 60% by weight, based on the total weight of the polyurethane contained in the polyurethane slurry. When the diol compound (component (D)) of the present invention is used to prepare the polyurethane, the polyurethane slurry having the above-described properties is easily obtained.
Methods for preparing a microporous sheet for artificial leathers from a polyurethane of the present invention include a wet method which comprises coating or impregnating a substrate such as a film or non-woven fabric with a polyurethane solution or slurry, immersing the substrate in a coagulating liquid, such as water, methanol, ethanol or propanol, which is a non-solvent for the polyurethane and is miscible with the solvent used, and coagulating the polyurethane to thereby form a microporous sheet; a dry method which comprises coating or impregnating a substrate such as a film or non-woven fabric with a polyurethane solution or slurry, and drying the substrate to evaporate the solvent used in a humid atmosphere. In a dry method using a polyurethane slurry, an organic solvent having a boiling point of not more than about 120° C., preferably not more than 100° C., and having a solubility at 25° C. in the organic solvent of from 1 to 50 g per 100 g of the organic solvent used is preferred.
As solvents satisfying the above-criteria, there can be exemplified methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, ethyl formate, butyl formate and a mixed solvent of not more than about 50% by weight of tetrahydrofuran or dioxane and any of the above-mentioned solvents.
According to the present invention, it is possible to provide a thermoplastic polyurethane suitable for preparing artificial leathers having various properties similar to natural leather.
The present invention is more specifically illustrated in the following examples. MW in the examples means number average molecular weight. The various physical properties mentioned in the examples were determined as follows:
1. Tensile Stresses at 5% and 20% Elongations, Elongation Recovery at 50% Elongation
The polyurethane obtained in accordance with the present invention was dissolved in dimethylformamide (DMF) to form a DMF solution containing 10% by weight of the polyurethane. A 150 micron thick film of the polyurethane was prepared by coating the solution on a glass plate and drying the glass plate with the film thereon at 70° C. for 24 hours. The film stripped from the plate was then dried at 80° C. for 2 hours at a reduced pressure of 10 mmHg.
A test piece having a length of 9 cm and a width of 1 cm was cut out from the film and was drawn out at a rate of 100% per minute (50 mm/minute) at a temperature of 20° C. using an Elongation Test Machine. (2 cm of each end of the test piece was held by the Machine.) The tensile stress at 5% or 20% elongation was calculated by dividing the weight of the load at 5% or 20% elongation by the original cross-sectional area of the piece, respectively.
The elongation recovery at 50% elongation is a percent value which was calculated by dividing the recovered elongation after removing the load at 50% elongation by the 50% elongation.
2. Strength at Breakage of Polyurethane Film After Raying for 48 Hours (kg/mm 2 )
The strength at breakage of the test piece of the polyurethane film obtained as shown in Test 1 was measured using an Elongation Test Machine after exposing the film to a carbon arc light for 48 hours in a fade-O-meter. The preferred strength at breakage is more than 2 kg/mm 2 .
3. Frictional Coefficient of Polyurethane Film (μ)
A test piece having a length of 4 cm and a width of 2.5 cm was cut out from a polyurethane film obtained as described for Test 1. The test piece was placed on a smooth surface of a stainless steel plate and a load (W) of 500 g/10 cm 2 applied. The force (F) needed to draw the test piece at a rate of 1 m/minute at 20° C. was measured. Th frictional coefficient (μ) was calculated by the following formula:
μ=F/W
The preferred frictional coefficient is from 0.3 to 0.85 for a polyurethane used for a porous layer or base layer, and is less than 0.3 for a polyurethane used for a surface finishing layer.
4. Resistance to Organic Solvents
Using a GAKUSHIN Type Friction Resistance Test Machine (Daiei Scientific Exact Machines Mfg. Co., Ltd.), a surface of an artificial leather obtained in the present invention was rubbed 100 times with a cotton fabric impregnated with toluene, ethyl acetate or ethyl alcohol under a load of 500 g. The change in the appearance of the rubbed surface was evaluated by the naked eye and grading was as follows:
______________________________________ excellent change of appearance scarcely occurred good change of appearance slightly occurred poor change of appearance considerably occurred______________________________________
5. Resistance to Gases
5-1. Nitrogen Oxide Gas
A polyurethane film obtained as described for Test 1 was exposed to nitrogen oxide gas in accordance with JIS-L-0855. The yellowness of the exposed film was evaluated by the naked eye.
5-2. Sunlight
A polyurethane film obtained as described for Test 1 was exposed to sunlight for 20 fine days (during from May to September) on a 45° inclined plate facing south. The yellowness of the exposed film was evaluated by the naked eye. Preferred values for both tests are not less than 3. Grading was as follows:
______________________________________ 5 almost no yellow color 4 slight yellow color 3 appreciable yellow color 2 considerable yellow color 1 exorbitant yellow color______________________________________
6. Resistance to Microorganisms
6-1. Polyurethane Film
A polyurethane film (obtained as described for Test 1) fixed on a plastic plate after 10% elongation was buried in wet soil containing about 40% by weight of water at a temperature of 30° C. Resistance to microorganisms was shown as the number of days until a crack occurs in the film for the first time. A preferred value is more than 100 days.
6-2. Artificial Leather
An artificial leather obtained in accordance with the present invention was immersed in a 0.2% by weight aqueous solution of soap at 40° C. for 10 hours, and then was buried in wet soil containing about 40% by weight of water at a temperature of 30° C. Resistance to microorganisms was shown as the number of days until a crack occurs in the leather for the first time. A preferred value is more than 100 days.
7. Cold Resistance
An artificial leather obtained in the present invention was bent 100,000 cycles at a temperature of -10° C. in accordance with JIS-K-6505. The degree of collapse of the leather was evaluated by the naked eye. The preferred value is not less than 3. Grading was as follows:
______________________________________ 5 collapse scarcely occurred 4 collapse slightly occurred 3 collapse appreciably occurred 2 collapse considerably occurred 1 collapse greatly occurred______________________________________
8. Average Diameter of Particles
A polyurethane slurry obtained in accordance with the present invention was transferred to a test flask equipped with a stirrer while keeping the temperature when the slurry polymerization was completed, and was then diluted by the solvent used in the polymerization with stirring to form a polyurethane slurry containing 5% by weight of the polyurethane. After cooling the diluted slurry to 25° C. with stirring, a drop of the slurry was placed on a transparent glass plate and covered by a cover glass. The drop was observed with an optical microscope at a magnification of 100 ×, and a microphotograph of the drop taken. The diameter of each particles in a 4 cm 2 area of the microphotograph was measured. The average diameter of the particles represents the mean value of the measured diameters.
9. Weight Ratio of Particles
The 5% polyurethane slurry (Wo g) obtained as described for Test 8 was taken into a centrifugal sedimentation tube. At 25° C., the slurry in the tube was allowed to sediment centrifugally for 15 minutes at 1500 rpm. The supernatant liquid was removed by decantation, and the remaining polyurethane particle part dried at 105° C. to a constant weight and weighed (Ws g).
A part of the same slurry was taken into a weighing bottle at the time of taking the slurry into the sedimentation tube and evaporated to dryness. The concentration of polyurethane (α%) contained in the slurry was measured.
The weight ratio of the particles in the polyurethane slurry was calculated by the following formula: ##EQU1##
10. Intrinsic Viscosity(η)
Intrinsic viscosity of the polyurethane obtained in accordance with the present invention was measured at 30° C. in dimethylformamide.
11. Permeability
A non-woven fabric having a 0.25 g/cm 2 apparent density which was 1 mm thick was prepared by needle punching a web consisting of polyethylene terephthalate staples (1.2 denier; 51 mm length) at a density of 800 counts/cm 2 and then heat-pressing at 130° C. and 0.2 kg/cm 2 for 90 seconds.
The fabric was floated on a polyurethane slurry (20% by weight) obtained in accordance with the present invention. The rate of the slurry permeating through the fabric was measured and graded as follows:
______________________________________ excellent the rate is fast (less than about 10 seconds) good the rate is medium (from about 11 to about 30 seconds) poor the rate is slow (more than 60 seconds)______________________________________
12. Appearance of Film Surface
A 1 mm thick film of polyurethane was prepared by coating a polyurethane slurry (20% by weight) obtained in accordance with the present invention on a glass plate, immersing the glass plate with the film thereon in methanol at 25° C. for 20 minutes to coagulate the polyurethane and drying the film at 65° C. for 20 minutes. The appearance of the polyurethane film surface was observed using an optical microscope at a magnification of 100 X. Grading was as follows:
______________________________________ excellent fine, even surface good almost even surface poor uneven surface______________________________________
13. Heat Deformation Temperature
A test piece having a length of 2 cm and a width of 5 mm was cut out from a polyurethane film obtained as described for Test 1. The film was fixed on a stand by clipping one end (0.5 cm) of the piece, and a load of one tenth of g/m 2 of the piece was hung on the other end (0.5 cm) of the piece. The test piece was immersed in silicon oil, and the temperature of the silicon oil was raised at a rate of 5° C./min. The relation between temperature and strain was recorded, and the temperature at which the test piece began to suddently flow was designated as the heat deformation temperature. The preferred temperature is more than 145° C.
14. Repulsive Resilience
A test piece having a length of 9 cm and a width of 1 cm was cut out from a polyurethane film obtained as described for Test 1. The test piece was folded into a rectangular form 4.5 cm long and 1 cm wide and was subjected to a load of 5 kg/cm 2 for one hour. After releasing the load, the opening angle (θ°) of the folded piece (the angle formed between the two rectangular planes) was measured. Repulsive resilience was calculated by the following formula: ##EQU2## Larger values show a greater repulsive resilience. The preferred repulsive resilience is from 60% to 80%.
15. Practical Durability
A pair of sport shoes was conventionally prepared from artificial leathers obtained in accordance with the present invention. The pair of sport shoes was worn for 3 months with weekly washing with an aqueous solution containing 0.5% by weight soap for 30 minutes at 40° C.
The degree of collapse of the shoes surface was evaluated by the naked eye. Grading was as follows:
______________________________________ 5 collapse scarcely occurred 4 collapse slightly occurred 3 collapse appreciably occurred 2 collapse considerably occurred 1 collapse greatly occurred______________________________________
16. pH
A mixture of 1 g of a diol compound (component (D)) and 99 g of pure water was heated while stirring, boiled for 5 minutes and then cooled while stirring to room temperature (about 20° C.). After removing precipitated foreign matter from the obtained solution by filtration using filter paper, the pH of the filtrate was measured using a glass electrode in JIS-Z-3802-7 at room temperature.
EXAMPLE 1
A reactor fitted with a stirrer and a condenser was charged with 475 g of polybutylene adipate having an average molecular weight of 1,720 (component (A)), 75 g of an adduct of ethylene oxide (2.23 mol adduct) and 2,2-bis(4-hydroxyphenyl) propane having an average molecular weight of 326 (pH=6.8) (component (D)), 365.7 g of diphenylmethane-4,4'-diisocyanate (component (C)), 229 g of dimethylformamide (solvent) and 0.01 g of triethylene diamine (catalyst), and the system reacted for 100 minutes at a temperature of 40° C. under normal atmospheric pressure to prepare a prepolymer. 84.3 g of 1,4-butane diol (component (B)) and 2 g of triethylene diamine (catalyst) were added to the prepolymer solution, and the mixture reacted for 200 minutes at a temperature of 40° C. under normal atmospheric pressure while gradually adding 3,971 g of dimethylformamide to obtain a polyurethane solution containing 20% by weight of polyurethane. The obtained polyurethane solution was diluted with dimethylformamide to a solids concentration of 10% by weight.
An artificial leather was then prepared in the following manner. A non-woven fabric 1.2 mm thick having a 0.25 g/cm 3 apparent density which consisted of polyethylene terephthalate staples (1.2 denier; 51 mm length) was immersed in the polyurethane solution (10% by weight) and then squeezed by nip rolls to adjust the amount of the solution impregnated to 1,800 g/m 2 . The impregnated non-woven fabric was then immersed in water at 40° C. for 30 minutes to coagulate the polyurethane, and then dried at 110° C. for 10 minutes.
The above-mentioned polyurethane solution was then coated on a surface of the obtained fabric using a knife coater in an amount of 200 g/m 2 (calculated in terms of polyurethane). The coated fabric was immersed in water at 40° C. for 1 hour to coagulate the polyurethane and form a porous surface (0.5 mm thick), and then dried at 110° C. for 10 minutes.
The above-mentioned polyurethane solution was then coated on the resulting porous surface of the fabric using a gravure roller to form a 15μ thick surface finishing layer, and the obtained artificial leather was dried at 110° C. for 10 minutes.
The result of testing the physical and chemical properties of this polyurethane were as shown in Table III below.
EXAMPLES 2-14
By the same procedure as in Example 1, a polyurethane was produced by reacting a long-chain diol, a chain extender, an organic diisocyanate and a diol compound as disclosed in Table I. The results of testing the physical and chemical properties of the obtained polyurethanes were as shown in Table II below.
COMPARATIVE EXAMPLES 1-9
By the same procedure as in Example 1, a polyurethane was produced by reacting a long-chain diol, a chain-extender, an organic diisocyanate and a diol compound as disclosed in Table II. The results of testing the physical and chemical properties of the obtained polyurethanes were as shown in Table IV below.
TABLE I__________________________________________________________________________Long-chain diol (A) Nitrogen (D) Polyester atom component diol/ content content Polyether Diol com- in the in the diol Chain- Organic pound (D) poly- poly-Polyester Polyether (Weight extender diisocyanate Diol urethane urethanediol diol ratio) (B) (C) compound pH (Wt %) (Wt %)__________________________________________________________________________Ex. (1)*.sup.1 (2)*.sup.2 (3) (4)*.sup.3 (5)*.sup.4 (6)*.sup.5 (7) (8) (9)__________________________________________________________________________ PBA BG MDI BPA . EO1 (MW 1720) -- -- 84.3g 365.7g 75g 6.8 4.1 7.5 475g (MW 326) PEA BG MDI HBPA . EO2 (MW 1750) -- -- 82.7g 358.7g 75g 6.6 40.0 7.5 483.6g (MW 340) PBA BG MDI BPA . PO3 (MW 1720) -- -- 85.9g 369.1g 100g 6.4 4.1 10.0 445g (MW 410) PBA BG MDI HBPA . PO4 (MW 2500) -- -- 80.3g 345.1g 150g 7.3 3.9 15.0 424.6g (MW 500__________________________________________________________________________Ex. (1) (2) (3) (4) (5) (6) (7) (8) (9)__________________________________________________________________________ PEA EG MDI BPA . EO5 (MW 1750) -- -- 67.6g 387.2g 50g 6.8 4.3 5.0 495.2g (MW 326) PEA BG MDI HBPA6 (MW 1750) -- -- 105.7g 397.6g 30g 7.0 4.5 3.0 466.7g (MW 240) PBA PTG BG MDI BPA . EO7 (MW 1700) (MW 1700) 40/60 85g 365g 70g 6.2 4.1 7 192g 288g (MW 326) PBA PTG BG MDI BPA . PO8 (MW 1700) (MW 1700) 50/50 86.3g 370.7g 100g 6.4 4.2 10 221.5g 221.5g (MW 410) PEA PTG BG MDI HBPA . PO9 (MW 2500) (MW 2500) 50/50 80.3g 345.1g 150g 7.3 3.9 15 212.3g 212.3g (MW 500) PBA PTG BG MDI BPA . EO10 (MW 1700) (MW 1700) 80/20 85g 365g 70g 6.8 4.1 7 384g 96g (MW 326) PTG BG MDI BPA . PO11 -- (MW 1700) -- 86.3g 370.7g 100g 6.4 4.2 10 443g (MW 410) PTG EG MDI BPA . EO12 -- (MW 1700) -- 68.4g 391.8g 50g 5.5 4.4 5.0 489.8g (MW 326) PBA BG MDI BPA . EO13 (MW 1700) -- -- 141.8g 514.4g 100g 6.2 5.8 10.0 243.8g (MW 326) PBA BG MDI HBPA . PO14 (MW 1700) -- -- 135.7g 492g 150g 6.8 5.5 15.0 222.3g (MW 500)__________________________________________________________________________
TABLE II__________________________________________________________________________Long-chain diol (A) Nitrogen (D) Polyester atom component diol/ content content Polyether Diol com- in the in the diol Chain- Organic pound (D) poly- poly-Polyester Polyether (Weight extender diisocyanate Diol urethane urethanediol diol ratio) (B) (C) compound pH (Wt %) (Wt %)__________________________________________________________________________Com-para-tiveEx. (1)*.sup.1 (2)*.sup.2 (3) (4)*.sup.3 (5)*.sup.4 (6)*.sup.5 (7) (8) (9)__________________________________________________________________________ PBA BG MDI1 (MW 1720) -- -- 99.1 g 359.6 g -- -- 4.0 0 541.3 g PBA BG MDI HBPA . PO2 (MW 2500) -- -- 56.5 g 238.6 g 20 g 7.3 2.7 2.0 684.9g (MW 500) PBA BG MDI BPA . EO3 (MW 1720) -- -- 101 g 461.8 g 180 g 6.8 5.2 18.0 257.2g (MW 326) PBA PTG BG MDI4 (MW 1700) (MW 1700) 50/50 99.8 g 361.8 g -- -- 4.1 0 269.2 g 2609.2 g__________________________________________________________________________Com-para-tiveEx. (1) (2) (3) (4) (5) (6) (7) (8) (9)__________________________________________________________________________ PBA PTG BG MDI HBPA . PO5 (MW 2500) (MW 2500) 60/40 56.5 g 236.6 g 20 g 7.3 2.7 2.0 410.9 g 274 g (MW 500) PBA PTG BG MDI BPA . EO6 (MW 1700) (MW 1700) 70/30 101.2 g 462.5 g 180 g 6.8 5.2 18.0 179.5 g 76.9 g (MW 326) PTG BG MDI HBPA . PO7 -- (MW 2500) -- 56.5 g 238.6 g 20 g 7.3 2.7 2.0 684.9 g (MW 500) PTG BG MDI HBPA . EO8 -- (MW 1700) -- 101.2 g 462.5 g 180 g 6.6 5.2 18.0 256.3 g (MW 326) PTG BG MDI BPA . EO9 -- (MW 1700) -- 140.7 g 554.9 g 180 g 6.8 6.2 18.0 124.4 g (MW 326)__________________________________________________________________________Footnotes from Tables I, II and V*.sup.1 PBA: polybutylene adipate PEA: polyethylene adipate PCL: polycaprolactone diol PHA: polyhexamethylene adipate*.sup.2 PTG: polytetramethyleneether glycol PEG: polyethylene glycol*.sup.3 BG: 1,4-butane diol EG: ethylene glycol*.sup.4 MDI: diphenylmethane-4,4'-diisocyanate XDI: p-xylylene diisocyanate*.sup.5 BPA . EO: an adduct of bisphenol A and ethylene oxide HBPA: 2,2-bis(4-hydroxycyclohexyl)propane BPA . PO: an adduct of bisphenol A and propylene oxide HBPA . EO: an adduct of 2,2-bis(4-hydroxycyclohexyl) propane and ethylene oxide HBPA . PO: an adduct of 2,2-bis(4-hydroxycyclohexyl) propane and propylene oxide BrBPA . EO: an adduct of 2,2-bis(4-hydroxy-3-bromophenyl) propane and ethylene oxide__________________________________________________________________________
TABLE III__________________________________________________________________________Elasticity Strength Resistance to Elonga- after Resist- microorganisms Tensile Tensile tion raying Fric- Resist- ance to Poly- Artifi- stress stress recovery for tional ance to nitrogen urethane cial Cold at 5% at 20% at 50% 48 hours coeffi- organic oxide film leather resist-Ex- (kg/mm.sup.2) (kg/mm.sup.2) (%) (kg/mm.sup.2) cient solvents gas (days) (days) anceample (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)__________________________________________________________________________1 0.29 0.56 80 2.6 0.66 good 4 200 200 4-52 0.27 0.53 82 2.6 0.71 good 4 200 200 4-53 0.35 0.68 77 3.2 0.55 good 5 300 300 4-54 0.45 0.86 60 3.5 0.43 good 5 300 300 4-55 0.25 0.49 83 2.8 0.77 good 4 200 200 4-56 0.37 0.74 85 2.6 0.52 good 3 100 100 4-57 0.25 0.49 83 2.5 0.78 good 4 more more 4-5 than than 300 3008 0.34 0.68 78 3.1 0.56 good 5 more more than than 4-5 300 3009 0.44 0.86 62 3.4 0.44 good 5 more more than than 4-5 300 30010 0.27 0.53 81 2.9 0.72 good 4 150 150 4-511 0.32 0.63 80 2.9 0.60 good 5 300 300 512 0.23 0.45 85 2.5 0.83 good 4 300 300 513 2.40 3.84 56 3.1 0.18 excel- 5 300 300 3 lent14 2.80 4.48 54 3.5 0.17 excel- 5 300 300 3 lent__________________________________________________________________________
TABLE IV__________________________________________________________________________Elasticity Strength Resistance to Elonga- after Resist- microorganismsCom- Tensile Tensile tion raying Fric- Resist- ance to Poly- Artifi-para- stress stress recovery for tional ance to nitrogen urethane cial Coldtive at 5% at 20% at 50% 48 hours coeffi- organic oxide film leather resist-Ex- (kg/mm.sup.2) (kg/mm.sup.2) (%) (kg/mm.sup.2) cient solvents gas (days) (days) anceample (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)__________________________________________________________________________1 0.26 0.51 92 2.0 0.77 good 1 20 15 4-52 0.08 0.16 91 1.8 more poor 2 30 20 4-5 than 1.03 3.30 3.10 47 3.6 0.12 excel- 4 300 300 1 lent4 0.25 0.49 93 1.1 0.80 good 1 20 19 4-55 0.08 0.16 92 2.1 more poor 2 40 35 4-5 than 1.06 3.20 3.00 49 3.6 0.12 excel- 4 300 300 1 lent7 0.07 0.14 92 1.8 more poor 2 300 300 4-5 than 1.08 3.03 2.90 52 3.0 0.13 excel- 4 300 300 1 lent9 3.05 2.95 48 3.2 0.13 excel- 3 300 300 1 lent__________________________________________________________________________
The polyurethanes obtained in accordance with the present invention (Examples 1-14) had moderate elasticity suitable for artificial leathers and excellent properties, such as resistance to nitrogen oxide gas, microorganisms and cold.
When a mixture of a polyester diol and a polyether diol was used as the long-chain diol component (Examples 7-10), the obtained polyurethane had, in particular, excellent resistance to microorganisms.
When a polyether diol was used as the long-chain diol component (Examples 11 and 12), the obtained polyurethane had, in particular, excellent resistance to cold. A polyurethane having a nitrogen atom content of from 4.7% to 6.0% by weight (Examples 13 and 14) had, in particular, excellent resistance to organic solvents and a low frictional coefficient, and was suitable for a surface finishing polymer of an artificial leather.
The polyurethanes in the Comparative Examples which were out of scope of the present invention had at least one disadvantage. The polyurethane which did not contain component (D) (Comparative Examples 1 and 4) had poor resistances to nitrogen oxide gas and microorganisms. The polyurethane which had a nitrogen atom content of less than 3% by weight and contained component (D) in an amount of less than 3% by weight (Comparative Examplees 2, 5 and 7) had too low an elastic modulus, and hence was not suitable for artificial leathers. The polyurethane which had a nitrogen atom content of more than 6% by weight and/or which had a component (D) content of more than 15% by weight (Comparative Examples 3, 6, 8 and 9) had too high an elastic modulus and a poor resistance to cold.
EXAMPLE 15
A reactor fitted with a stirrer and a condenser was charged with 723 g of polybutylene adipate having an average molecular weight of 1,730 (component (A)), 162 g of polytetramethyleneether glycol having an average weight of 1,550 (component (A)), 156 g of an adduct of 2,2-bis(4-hydroxyphenyl)propane and ethylene oxide having an average molecular weight of 326 (pH=6.8) (component (D)), 735 g of diphenylmethane-4,4'-diisocyanate (component (C)), 0.05 g of triethylene diamine (catalyst) and 444 g of methyl ethyl ketone (solvent), and the system reacted for 80 minutes at a temperature of 45° C. under normal atmospheric pressure to prepare a prepolymer. Over the course of the reaction the temperature gradually rose up to 58° C. 171 g of 1,4-butane diol (component (B)), 1,500 g of methyl ethyl ketone and 4 g of triethylene diamine were then added to the prepolymer solution, and the mixture reacted for 30 minutes at a temperature of between 70° C. and 75° C. under normal atmospheric pressure to provide a highly viscous, milky paste. After gradually adding 5,844 g of methyl ethyl ketone to the paste, the reaction was continued for 150 minutes at a temperature of 73° C. under normal atmospheric pressure to obtain a bluish milky polyurethane slurry containing 20% by weight polyurethane and having a viscosity of 650 cps measured at 70° C.
An artificial leather was prepared in the following manner. With stirring by a homomixer, 250 g of water was added dropwise to 1,000 g of the polyurethane slurry over the course of 30 minutes. The resulting mixed slurry had a polyurethane concentration of 16% by weight and a viscosity of 40° C. of 3,000 cps. A 1.2 mm thick non-woven fabric having an apparent density of 0.25 g/cm 3 which consists of polyethylene terephthalate staples (1.2 denier; 51 mm length) was immersed in the mixed slurry (16% by weight) and then squeezed by nip rolls to adjust the amount of the slurry impregnated therein to 1,125 g/m 2 . The impregnated fabric was passed through methanol at 35° C. for 30 seconds, then dried at 60° C. for 10 minutes and further dried at 100° C. for 10 minutes.
The above-obtained mixed slurry was coated on the surface of the obtained fabric using a knife coater in an amount of 200 g/m 2 (calculated in terms of polyurethane). The coated fabric was passed through methanol at 35° C. for 30 seconds, then dried at 60° C. for 10 minutes and further dried at 100° C. for 10 minutes to form a porous surface (0.5 mm thick).
The above obtained mixed slurry was coated on the porous surface of the fabric using a gravure roller to form a 15μ thick surface finishing layer, and the obtained artificial leather was dried at 110° C. for 10 minutes.
The results of testing the physical and chemical properties of the obtained polyurethane slurry and polyurethane were as shown in Table VI below.
EXAMPLES 16 AND 17, COMPARATIVE EXAMPLES 10 and 11
By the same procedure as in Example 15, a polyurethane slurry was produced by reacting a long-chain diol, a chain-extender, an organic diisocyanate and a diol compound as disclosed in Table V. The results of testing the physical and chemical properties of the obtained polyurethane slurry and polyurethane were as shown in Table VI below.
EXAMPLE 18
A reactor fillted with a stirrer and a condenser was charged with 577 g of polyethylene adipate having an average molecular weight of 1,700 (component (A)), 128 g of polyethylene glycol having an average molecular weight of 1,540 (component (A)), 321 g of an adduct of 2,2-bis (4-hydroxycyclohexyl)propane and propylene oxide having an average molecular weight of 556 (pH=6.6) (component (D)), 888 g of diphenylmethane-4,4'-diisocyanate (component (C)), 0.08 g of triethylene diamine (catalyst) and 479 g of a mixed solvent of methyl ethyl ketone and tetrahydrofuran (weight ratio of 90:10), and the system reacted for 80 minutes at a temperature of between 55° C. and 66° C. under normal atmospheric pressure to prepare a prepolymer. 155 g of ethylene glycol (component (B)), 1,590 g of the mixed solvent and 4.8 g of triethylene diamine were added to the prepolymer solution, and the mixture reacted for 20 minutes under normal atmospheric pressure, the temperature raising from 55° C. to 70° C. over the course of the reaction. Thereafter, while gradually adding 6,207 g of the mixed solvent to the mixture, the reaction was continued for 130 minutes at a temperature of between 66° C. and 68° C. under normal atmospheric pressure to obtain a polyurethane slurry containing 20% by weight of polyurethane. An artificial leather was then prepared as described in Example 15. The results of testing the physical and chemical properties of the obtained polyurethane slurry and polyurethane were as shown in Table VI below.
EXAMPLES 19-21
By the same procedure as in Example 18, a polyurethane slurry was produced by reacting a long-chain diol, a chain-extender, an organic diisocyanate and a diol compound as disclosed in Table V. The results of testing the physical and chemical properties of the obtained polyurethane slurry and polyurethane were as shown in Table VI below.
In the following Tables the abbreviations used are the same as those used in earlier Tables I and II.
TABLE V__________________________________________________________________________Long-chain diol (A) Nitrogen (D) Polyester atom component diol/ content content Polyether Diol com- in the in the diol Chain- pound (D) poly- poly- Polyester Polyether (Weight extender Organic Diol urethane urethaneEx- diol diol ratio) (B) diisocyanate compound pH (Wt %) (Wt %)ample (1) *1 (2) *2 (3) (4) *3 (5) *4 (6) *5 (7) (8) (9)__________________________________________________________________________ PBA PTG BG MDI BPA . EO15 (MW 1730) (MW 1550 82/18 171 g 735 g 156 g 6.8 4.23 8.0 723 g 162 g (MW 326 g) PBA PTG BG MDI BPA . EO16 (MW 1730) (MW 1550) 82/18 225 g 545 g 96 g 6.8 4.14 4.0 976 g 219 g (MW 326) PBA PTG BG MDI BPA . EO17 (MW 1730) (MW 1550) 82/18 153 g 684 g 223 g 6.8 4.80 14.0 437 g 98 g (MW 326) PEA PEG EG MDI HBPA . PO18 (MW 1700) (MW 1540) 82/18 155 g 888 g 321 g 6.6 4.80 15.0 577 g 128 g (MW 556)__________________________________________________________________________Ex-ample (1) (2) (3) (4) (5) (6) (7) (8) (9)__________________________________________________________________________ PCL PEG EG MDI BrBPA . EO19 (MW 1730) (MW 1540) 88/12 167 g 722 g 164 g 6.7 3.70 7.5 1000 g 131 g (MW 486) PCL PEG EG MDI HBPA20 (MW 1730) (MW 1540) 89/11 158g 696g 74g 6.4 3.71 3.5 1048 g 126 g (MW 236) PHA PEG EG XDI BPA . EO21 (MW 1750) (MW 1540) 88/12 180 g 572 g 119 g 6.8 3.25 5.5 967 g 129 g (MW 326)Com-para- PBA PTG BG MDI BPA . EOtive (MW 1730) (MW 1550) 82/18 171 g 735 g 156 g 7.8 4.25 8.0Ex- 723 g 162 g (MW 326)ample10Com-para- PBA PTG BGT MDI BPA . EOtive (MW 1730) (MW 1550) 82/18 171 g 735 g 156 g 4.6 4.25 8.0Ex- 723 g 162 g (MW 326)ample11__________________________________________________________________________
TABLE VI__________________________________________________________________________Properties of Properties of polyurethanepolyurethane slurry Resist Aver- ance to age micro-Weight dia- Elon- Heat organ-ratio meter gation defor- isms Resistance Repul-of of Appear- Tensile re- mation (Arti- to gases sive Prac-arti- parti- ance stress covery tempe- ficial Nitro- resili- Cold ticalcles cles Perme- of film at 5% at 50% rature leath- gen Sun- ence resist- dura-Ex- (Wt %) (μ) ability surface [η] (kg/mm.sup.2) (%) (°C.) er) oxide light (%) ance bilityample(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14)__________________________________________________________________________15 38 5 excel- excel- 0.89 0.33 80 155 more 5 4 72 5 5 lent lent than 6 months16 42 15 good good 0.88 0.30 84 158 more 5 4 75 5 5 than 6 months17 44 8 excel- excel- 0.88 0.38 76 154 more 5 5 70 4 5 lent lent than 6 months18 25 2 excel- good 0.90 0.35 78 153 more 5 4 70 4 5 lent than 6 months19 35 4 excel- good 0.86 0.31 84 153 more 5 4 75 5 5 lent than 6 months20 48 10 excel- good 0.86 0.30 85 153 more 5 4 76 5 5 lent than 6 months21 12 0.3 excel- good 0.92 0.25 86 152 more 5 5 78 5 5 lent than 6 monthsCom-para-tive (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14)Ex-ample10 38 8 poor poor 0.78 0.33 81 155 more 5 4 78 5 5 than 6 months11 38 5 excel- poor 0.58 0.33 79 134 4 5 3 72 4 4 lent months__________________________________________________________________________
Since the polyurethane slurries obtained in accordance with the present invention (Examples 15-21) had good permeability and a good film surface appearance, they were highly suitable for producing artificial leathers. In addition, the polyurethanes in Examples 15-21 had moderate elasticity, high heat deformation temperature, excellent resistance to microorganisms, gases and cold, good repulsive resilience and practical durability.
The polyurethane slurry in Comparative Example 10, which was obtained by using a diol compound (component (D)) having a pH of more than about 7.5 (out of the scope of the present invention), was a highly viscous fluid having poor permeability so that the polyurethane slurry was not suitable for producing artificial leathers. The polyurethane slurry in Comparative Example 11, which was obtained by using a diol compound having a pH of less than about 5.0 (out of the scope of the present invention), had a poor film surface appearance so that the polyurethane slurry was not suitable for producing artificial leathers. In addition, the polyurethane was poor in resistance to microorganisms and had a poor heat deformation temperature.
While the invention has been described in detail and 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 thermoplastic polyurethane comprising the polymerization product of a long-chain diol, a low molecular weight chain-extender, an organic diisocyanate and a specific diol compound. The specific diol compound is represented by the following formula: ##STR1## wherein R 1 and R 2 are hydrogen or an alkyl radical having from 1 to 3 carbon atoms, R 3 and R 4 are an alkylene radical having from 2 to 4 carbon atoms, Y is a bivalent radical selected from the group consisting of ##STR2## wherein x is hydrogen, chlorine, bromine or a methyl radical, m and n are positive integers satisfying the formula 2≦m+n≦10
when Y is ##STR3## or m and n are zero or positive intergers satisfying the formula 0≦m+n≦10
when Y is ##STR4## The thermoplastic polyurethanes are suitable for producing artificial leathers having improved properties such as moderate elasticity, resistance to microorganisms, cold, stickiness and nitrogen oxide gas.
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BACKGROUND OF THE INVENTION
The invention concerns a binding machine for materials such as carpets, carpet strips or the like with a machine frame carrying a drive motor, a transportation mechanism for the material to be bound, a binding mechanism with a needle guided essentially perpendicularly and a holder for the supply of binding thread as well as a supply of edging strip or binding tape if required.
Such binding machines are necessary in order to make carpets, carpet strips, etc. from floor covering materials delivered as yard goods. The binding provides not only an improved appearance of the cut edges but also prevents the edges from fraying.
A well known rug binding machine described in U.S. Pat. No. 2,547,821 is essentially constructed as a heavy sewing machine and has a very bulky base plate and a conventional projecting arm which carries the machine head. The machine is mounted on a heavy machine table which is mounted on wheels. The drive motor is located under the machine table. The known rug binding machine operates with two threads which are introduced independently from the top and from the bottom. To operate it, the heavy machine must be lifted onto the rug and the edges of the rug looped back 180° and inserted into the machine.
When the thread color is changed, if no disturbing threads of the lower thread are to be visible, the upper and lower threads must both be changed.
SUMMARY OF THE INVENTION
The purpose of the invention is to create a rug binding machine that can be manufactured more simply and is more easily operated than the known machines.
This task is solved according to the invention by arranging the machine frame with motor, transportation mechanism, and looping mechanism as well as the holders as an integral compact unit which can be handled and guided along the outside of the edge of the material by means of at least one handle or hand grip, that the base member, bearing part or support means which engages the material and partially raises the material in the zone of the edge being bound is designed very low or flat to the floor and that only a single binding thread is guided in from the top.
The thus-devised manual rug binding machine can be present and conveniently used in every floor covering operation since it requires no large storage space. The carpet can be placed flat on the floor and the binding machine placed at the edge of the carpet from the outside and slid along it by hand. When this occurs, a bearing part or support means engages the material and curves it up somewhat without the need of folding the carpet back over its entire length.
As a result of the fact that the machine operates with only one thread, not only is it easier to change the binding thread including threading, but storage in small plants is also facilitated, since for every color, in the minimum case, only one roll of thread need be on supply.
BRIEF DESCRIPTION OF THE DRAWINGS
For the purpose of illustrating the invention, there are shown in the drawings forms which are presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.
FIG. 1 shows a side elevation view of the rug binding machine according to the invention.
FIG. 2 shows a front elevation view seen from the working side.
FIG. 3 shows a schematic representation of the sewing and transportation mechanism in side elevation view.
FIG. 4 is a schematic top view of a bound material edge in a simplified and extremely coarse manner of representation for purposes of clairty of illustration.
FIGS. 5-9 show schematic representations of the binding mechanism in different states of operation viewed in the binding direction.
FIG. 10 shows a side view of the binding mechanism and particularly the looper, seen from the right in FIG. 3.
FIG. 11 is a top view of the carrier and pressure mechanism of another advantageous embodiment of a binding machine.
FIG. 12 is a partial cross-section view along line II-III of the carrier mechanism shown in FIG. 11 in its normal setting for binding straight edges.
FIG. 13 is a cross-section view of the carrier mechanism corresponding to FIG. 12 in a work setting for binding curves.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The rug binding machine 11 shown in the drawings is used to bind the edges 12 of a piece of material 13, e.g. carpeting, which is cut off from a roll. The machine 11 has a machine frame consisting of an upright column-like part 14, a lower base member, bearing part or support means 15 and holders 16 and 17 for the supply 18 of binding thread as well as a supply 19 of binding strip or tape. The binding thread supply consists of a very high and bulky spool of binding thread mounted on a spool core 20 which is seated on a plate 20' on the holder 16. The binding strip lies in the axial direction under the binding thread supply on the plate-shaped holder 17 which forms the lower edge of the machine together with the bottom side of the bearing part or support means 15. In the area of the lower edges of the machine, on the bearing part or support means 15 and holders 17, runners or roller 21 and 22 are provided, by means of which the machine may be moved along the floor. The runners may also be in the form of skids or the equivalent. The principal dimensions of the machine therefore lie in the vertical direction so that a very convenient machine results which may be used wherever carpet is to be laid.
Supporting table member 15 engages the underside of the material 13 providing support and has a relatively flat configuration. As FIG. 2 shows, the bearing or support member 15 is also very narrow in the direction of advance indicated by the arrow 23. Due to the runners or rolls 21 and 22 and the rolls 24 being mounted freely and extensibly on the upper side edges of the base member or support member 15, the material 13 can easily move over support means 15. FIG. 2 illustrates that the binding machine 11 can move along on the floor 25 during operation, while the carpet 13 to be bound, also lying on the floor, is arched up in the area or zone of support member or base plate 15 and settles down to the floor again after binding. Therefore, only the space of the carpet or rug itself is required for binding, i.e. the binding can take place in the space where the rug will later lie. FIG. 1 and FIG. 2 show that the material 13 is transported by a conveying or carrier mechanism means containing a roll 26 driven in steps, which is mounted in the bearing or support means 15 and which will be described in more detail below. Opposite roll 26 is an upper pressure roller 27, which is spring loaded in the downward direction and which presses the material 13 against the drive carrier roll 26, which is grooved for better conveying. The pressure roller 27 can be lifted manually by means of a lever 28. In the embodiment shown in FIGS. 1 and 2, the pressure roller is cylindrical.
The single binding thread 29 is supplied to the needle 32 of the binding mechanism 33, (FIG. 3) via a thread holder 30 and a conventional adjustable thread tightener 31 mounted on the column-shaped part 14.
A handle 34 is mounted on upright part 14 of the machine frame, containing a push-button switch 35 with which the motor 36 contained in part 14 can be set into operation. An electric or mechanical control means for control of the binding and conveying speed may be provided, the electrical connection cable 37 supplying current to the motor enters in the region of the handle.
The binding machine has a conventional strip inserting apparatus 38 which places a textile tape around the edge in a U-shape before binding in order to keep the fibers of the carpeting material from getting in between the individual binding threads. This binding tape 39 (FIG. 1) is completely covered by the binding yarn after binding. The details of the conventional tape inserting apparatus are not shown for reasons of simplifying the representation.
In FIG. 3, the mechanical structure of the binding and carrying mechanism is illustrated schematically. The electric geared drive motor 36 with a vertical axis is mounted inside the column-shaped part 14 of the binding machine. It acts via a bevel gear drive with a bevel pinion 40 and a bevel gear wheel 41 on a drive shaft 42 which is mounted essentially horizontially and carries a handwheel 43 on its rear free end. On its front end, i.e. left end in FIG. 3, it has a cam plate 44, a crank crankpin 45 and a crank 46 with a pin 47 which possesses significantly greater eccentricity than the crankpin 45 relative to the drive shaft 42. The crank 46 is adjustable on the crankpin 45 by means of clamping screws so that the relative position of the cranks with respect to each other is adjustable. A needle bar 48 is movably mounted, essentially vertically, in a needle guide 49. At its lower end, it carries a conventional needle 32 suited for relatively thick binding thread and can be moved up and down via a connecting rod 50 from the pin 47.
A connecting rod 51 on the crankpin 45 swivels a gear segment 52, which is capable of swiveling about an axle 53 that is essentially horizontal and points roughly in the direction of advance. The gear segment 52 engages gearwheel 54 mounted on a shaft 55. The latter is supported in bearing or support means 15 with a slight inclination with respect to the direction of advance in both the horizontal (see FIG. 10) lateral direction. A gripper 56 swivels together with gearwheel 54 and shaft 55. Gripper 56 comprises a gripper arm 57 curved approximately as an arc of a circle and connected to shaft 55 via an essentially radially directed swivel arm 58. FIG. 10 shows that the gripper arm 57 is somewhat laterally displaced with respect to the swivel arm 58 or it is curved so that it can grip around the needle 32.
The gripper arm 57 is designed in the shape of a fork 59 at its front end, having an inner shorter tine 60 and an outer longer tine. The inner tine 60, as shown in FIG. 5, passes in the lower position of the swivel arm 58 closer to needle 32 than the outer tine.
FIG. 10 also shows that the slope of the axle is selected such that the gripper 56 with its gripper arm 57 in the lower position runs behind needle 32 in the direction of advance 23 while the gripper arm in the upper position runs in front of needle 32 in the direction of advance, For the purpose of facilitating understanding, the direction of advance 23 here denotes the direction of entry of material 13 in the binding mechanism, while in reality the machine 11 moves against the direction of advance and the material 13 is normally stationary in the horizontal direction.
A guide 68 (see also FIGS. 5-8) guides both the edge 12 on the one side and the thread loop during the overedging on the side. The guide 68 is roughly conical in the direction of advance 23, and is supported by a leaf-spring 75 which introduces the threads individually and successively into the gap between itself and the bottom side of the guide, thus preventing the crossing of the threads. Besides a chamfer 77, the guide also has a cavity 76 for the gripper 56. Refer to FIG. 10 for the shape of the guide and leaf spring.
In FIG. 3, for the sake of simplicity, the pressure roller 27 is omitted from the carrier mechanism. The carrier roll 26 is hollow and designed in the shape of a can so that the gripper 56 is not impeded in its movement, which is described below. The roll 26 is mounted on one end of a shaft 61 which is rotatably mounted in the bearing part or support means 15. The outer ring of a clamping body lock mechanism 64 is actuated in steps via a lever 62 controlled by the cam disc 44 and a connecting rod 63, said locking mechanism taking the shaft 61 with it in one direction to execute a carrying step. A second clamping body locking mechanism 65 whose outer ring is fixed to its housing keeps the shaft 61 from rotating backward when the connecting rod 63 swivels in the opposite direction. The stroke of the lever 62 is adjustable by means of a limit screw, which is not shown, so that the step-wise rotation of the carrier roll 26 is infinitely adjustable.
Referring to FIGS. 5 to 9, the manner of functioning of the binding mechanism 33 is described below. FIG. 5 shows that after the needle 32 has pierced the material 13, the thread 29 guided through the eye 66 moves through the needle hole 67 formed by the needle twice, i.e. forth and back. FIG. 5 shows the mechanism shortly after the bottom dead center, i.e. the needle is already in its upward movement again and the gripper 56 has already moved in the swiveling direction which is counterclockwise as represented by the arrow. As a result of the upward movement of the needle, the thread no longer lies closely against the needle shaft but rather has formed a loop which is gripped by the gripper 56 with the inner tine 60 of the fork 59. The needle shaft is chamfered on the side where the fork passes it.
FIG. 6 now shows how the gripper 56 continues in its swivel movement in the counterclockwise direction as the needle 32 continues its upward movement and in so doing takes the loop of thread released by the needle with it. In FIG. 7, the gripper has already executed a turn through roughly 150° and the needle in its upward motion has already become free of the material 13. The thread loop carried by the fork 59 is folded around the edge 12 of the material 13. To prevent the thread from cutting into soft rug material, an angular but externally rounded guide 68 is installed in this region which covers the edge 12 but terminating in the binding direction shortly after the zone represented here as shown in the drawing so that the threads then enclose the edge 12 directly, i.e. with the binding tape between them, but which is not shown here for the sake of simplicity.
In the working position shown in FIG. 7, i.e. when the needle has left the hole 67, the carrier means is engaged and the rug material or entire machine 11 is moved forward a little by rotating the roll 26.
FIG. 8 shows the mechanism shortly after the top dead center, i.e. the needle 32 has already begun to move downward again while the gripper 56 is already beginning to turn back in the clockwise direction. As a result, the thread loop, which is still lying in the fork 59, has opened somewhat and the needle 32 is thrust into this thread loop. As the gripper 56 continues to turn or swivel in the clockwise direction, the loop emerges from the fork 59 and is drawn tight around the needle while the needle is now piercing the next or following hole in the material 13. The thread transferred by the needle from one hole to the next hole is now placed over one leg of the loop.
FIG. 9 shows the needle already in the next or following hole 67'. The gripper is still moving in the clockwise direction idly, while the needle pulls thread out of the supply via the thread tightener 31 as it moves downward in order to initiate a new operating cycle, which then begins again as shown in FIG. 5. Note that in the lower position shown in FIG. 5, the gripper 56 passes behind (but in the drawing in front of) the needle in the binding direction 23, while in FIG. 8, it passes in front of (but behind in the drawing) the needle 32 in the direction of advance 23. As a result, the needle can pierce across one leg of the thread loop.
FIG. 4 shows the binding process. FIG. 4 is a top view of the top side so that the thread 29 on the top is shown by solid lines and on the bottom by broken lines. Two threads pass through every hole 67, 67' 67'', running essentially parallel to the edge 12 on the bottom and climbing up the latter. On the top, they form the legs 70, 71 of a thread loop which runs around the next following hole. Every two neighboring legs 70, 71 of neighboring loops are bridged by a thread segment 72 emerging from the previous hole (e.g. 67) and passing into the following hole (e.g. 67'). Therefore, a binding chain is formed containing two parallel-running binding threads on both sides for each hole, while, in addition, a relatively narrow chain is formed on the top from the thread segments 72 running essentially in the direction of the edge and the arch of the thread loop. As a result, a clear boundary is formed between the binding and the pile of the rug. It should also be noted that for better illustration, the binding in FIG. 4 is shown with exaggerated spacing, while in reality the binding threads lie very closely together. Thus, the threads in reality do not run nearly as obliquely as shown in the drawing.
The advantageous roller drive mechanism keeps the stitches from being so close together that the material, especially rug material with a back of foam plastic, is broken apart. The small number of needle holes is also advantageous, because two threads can pass through each hole.
In the following, the modification shown in FIGS. 11 through 13 is described. The same parts carry the same reference numbers.
On the upright part 14 of the machine, a vertical guide bar 75 is mounted, which is embraced by the eye 76 of a holder 77 carrying an adjusting axis 78 at its free end. The holder 77 is adjustable by means of a set screw 79 on the guide rod 75 and can be secured against turning, e.g. by a flattening on the guide rod which is engaged by the set screw. The adjusting axis or axle 78 penetrates a bearing box 80 on which a conical pressure roller 27" is mounted so as to rotate about the turning axle or axis 81. Because the pressure roller can be swiveled away, the needle is easily accessible for threading and needle changing.
The adjusting axle is guided in a bore 83 of the bearing box 80 which goes through it obliquely, i.e. at an angle to the turning axle 81. The rotation of the bearing box about the adjusting axle is made difficult by means of a friction ring 82 held and kept under tension by a nut screwed onto the adjusting axle 78. Although manual adjustment is possible, spontaneous movement is impossible. The bearing box 80 has an adjusting area 85 which projects beyond the bearing face 84 and is knurled on its periphery so that it can be rotated as an adjusting knob.
The pressure roller 27' is mounted on the bearing face 84 and guided in the axial direction between the union bordering the adjustment area and a retaining ring. The increasing taper of the pressure roller 27 in the direction toward the needle is so great that, as FIG. 12 shows, the conical pressure area 86 of the pressure roller 27' runs parallel to the material 13 or the carrier roll 26 lying under the pressure roller. At its front side, facing the needle, the pressure roller has a larger diameter and is hollow so that the parts of the sewing mechanism, e.g. the gripper, are not impeded by it in any way. The holder 77 passes through the hollow space 87.
The part 14 forming the actual machine body is especially narrow at the level where the material is guided and equipped with thick roundings which deflect the edge 12 of the material away. In the intake zone (FIG. 1, bottom), an inner rounded edge guide 88 is provided which simultaneously defines a feed channel 89 for an ordinary binding tape. It is also equipped with a removable or swiveling straight guide 90 which partially overlaps the inner rounded edge guide 88.
In normal operation, the pressure roller 27' occupies a position such as shown in FIG. 12. In this case, the pressure face 86 lies on the material with linear contact so that the latter is gripped over a relatively large area and moved without leaving impressions. But now if one comes upon an outer or inner rounding, then the bearing box 80 is swiveled by rotation on the adjusting area 85 in such a way that the pressure face 86 in the zone facing away from the needle is lifted off the material surface and only the region of larger diameter of the conical pressure face lies on it. This region is relatively close to the needle. By appropriate choice of the chamfer of the bore 83 in the bearing box and the taper 86, this point can be moved even closer to the needle than shown in FIG. 13. The reduced pressure region makes it possible to turn the machine around small roundings without stitching too closely or too far apart.
As may be seen, the arrangement of the axes was selected such that with the pressure roller in the curve position shown in FIG. 13, the relative pressure of the pressure roller against the material is greater than in FIG. 12. This may be adjusted by turning the bearing box an appropriate distance by means of the adjusting knob 85.
In addition, during the binding of the inner edges, the inner rounded edge guide 88 becomes active by removing or folding back the straight guide 90. The machine can then be driven around relatively small inner roundings.
Numerous modifications of the embodiment shown and described are possible within the limits of the invention. Although the design with a bearing box capable of turning about a slanted axis is particularly simple, it is still possible to use a standard swivel mounting.
In view of the above, the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification as indicating the scope of the invention.
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A portable integral compact rug binding machine which may be guided along the outside edge of a carpet to be bound by means of a handle is disclosed. The rug binding machine is provided with a vertically mounted drive motor and a low or close to the floor base member wherein a portion or zone of the carpet being bound curves up and over the base plate or support means without need for folding the carpet back over its entire length. The binding machine performs the binding operation with the use of a single binding thread fed to the needle from above. A driven carrier roll is provided for moving the carpet with respect to the binding needle, and in one embodiment, an adjustable pressure roller is provided for enabling binding around curved edges of the carpeting.
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This application is a continuation of International Application PCT/EP02/13078 filed on Nov. 21, 2002 and which claims priority of Patent Application Serial No. 01/15560 filed in France on Nov. 23, 2001, the entire content of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
The invention relates to a motor vehicle wheel disc with arms, in particular for passenger car, formed in one piece from embossed sheet metal, which represents an excellent compromise in terms of weight, cost, style or freedom of possible added styling (decorative wheel cover for example).
In the designing of a sheet metal wheel for a motor vehicle, the general aim is to optimise the weight and cost of such a product. The development of embossing techniques, numeric simulation means, and materials has led to great progress over the last few years. However, the majority of products has remained within the concept of a substantially axisymmetric disc (i.e. one whose cross-sectional profile is virtually fixed in form), comprising perforations and sometimes embossing in the upper part.
This type of profile does not give the product a very enhanced style or image, which explains in most cases why manufacturers resort to a decorative wheel cover placed on the product when it is mounted on the vehicle.
One can count several attempts to create style directly from the sheet metal forming the wheel disc by forming deep embossed areas forming stiffeners and/or a particular assembly of the disc with the rim (under-seat, “full-face” assembly (i.e. disc whose radially outer edge includes the outer flange and seat of the rim), with the rim welded at the end, etc.) and sometimes associated with effects connected to painting. These attempts have not yet led to generalisation for reasons of excessive weight or difficulties in execution.
In general, the market for styled wheels for passenger cars is confined to the use of aluminium alloys. The process of manufacture (moulding, forging etc.) of these discs allows very broad freedom of style at reasonable weights, but has the disadvantage of being 4 to 8 (even 10) times more expensive.
The specification of DE 201 08 995-U discloses a wheel whose disc is formed from a single piece of embossed sheet metal, with an outer face and an inner face. This disc has a radially outer circular assembling part intended to be connected to a rim, a radially inner part for fixing and centering to a wheel hub with a bearing area having a given number of fixing apertures and ending radially inwardly with an edge which is turned axially outwardly or centering vent (aperture), and spokes connecting the inner and outer parts, each arm being disposed substantially opposite to one of the fixing apertures and the radially inner free edges of the radially outer circular part defining perforations with the free lateral edges of the arms. This disc has a substantially circular, plane bearing region and each arm comprises two lateral stiffening elements which extend radially from the bearing area to the radially outer circular assembly part and are disposed on either side of an intermediate strip axially set back towards the interior of the disc.
Although freedom of styling either bare or with an attached part (decorative wheel cover for example) is apparently obtained, such a disc has the disadvantage of requiring a relatively thick sheet metal to be able to withstand the forces to which it is subjected during operation, in particular in the joining region between the arms and the radially inner part for fixing and centering the disc.
Hereinafter:
the “outer face” of the disc will refer to the surface of revolution generated by rotation about the axis of rotation of the disc of the regions of the disc disposed axially outermost; the “internal face” of the disc, to the side of the disc oriented inwards, in particular the internal face of the bearing region is intended to come into contact with the outer surface of the wheel hub to which the disc is to be fixed; and the “external face” of the disc, to the side of the disc oriented outwards, which side is visible when the wheel is mounted on the vehicle.
SUMMARY OF THE INVENTION
The object of the invention is a similar wheel disc in which, in order to reinforce each arm mechanically, a pocket is housed in a position set back axially inwardly relative to the outer face of the disc, the pocket extending radially from the centering vent and including a fixing aperture and the adjacent part of the bearing region, along the central part of the arms and as far as the outer circular assembling part and in which the outer face connects each arm to the centering vent by a yoke offset axially outwardly relative to the bearing region.
The particular geometry of the radially inner part for fixing and centering the disc has the advantage of reducing the stress peaks withstood by this region during operation.
According to an advantageous embodiment, and taking into account a median axial plane between two adjacent fixing apertures, the axial distance separating the internal face of the yokes and the internal face of the bearing region is at all points greater than the initial thickness of the sheet metal forming the wheel disc.
Preferably, each pocket has a floor and a single closed side surrounding the floor. Each pocket therefore has a closed geometry.
According to a preferred embodiment, the arms have lateral edges turned down towards the inner face of the disc and have a section substantially in the shape of an M. It is advantageous if at a given radial distance, the lateral edges are offset axially outwardly relative to the inner face of the floor of the pocket of the arm. This arrangement has the advantage of limiting the consequences of pressure peaks on the arms during operation by preventing these pressure peaks from being transmitted to the more sensitive cut-out edges.
According to another preferred feature of the invention, the edges of the perforations are obtained by punching sheet metal and then folding down towards the internal face of the disc. This has the advantage of releasing a maximum of the perforated area and to ensure that no cut-out face is visible from the outer side.
Furthermore the aesthetic thus obtained is pleasing and the strong perforation lends, in addition to good ventilation of the brakes, considerable freedom of added style (decorative wheel cover).
The pockets may advantageously have a generally flattened oval shape with a width in the circumferential direction decreasing continuously from the fixing aperture to the radially outer circular part. In the same way, the pockets may have a depth which decreases continuously from the radially inner part to the radially outer circular part. The width, section and bending-resistance of the arms in the circumferential direction may also advantageously continuously decrease from the radially inner part to the radially outer circular part.
The object of these arrangements is to distribute the material in the best way in the arm where it is needed to reduce pressures during operation according to the stresses to which the arm is subjected.
Each bearing region about each fixing aperture may have at least two distinct bearing faces. Preferably, relative to the axis of a fixing aperture, the bearing region has a first bearing face disposed radially inward and two other bearing faces disposed axially outward and circumferentially on either side of the fixing aperture.
Advantageously, the floor of the pockets may have convex or concave regions. It may also have punched holes. Such a hole may be a standard perforation or act as a fixing for a styled part such as a decorative wheel cover.
The final shape of the arms and of the perforations of the discs according to the invention may be obtained simultaneously in one or more embossing operations. Preferably, after being cut out, the edges of the perforations are trimmed from an embossed part before being turned down.
The radially inner part of the centering vent may also comprise preferred bearing distances opposite to each fixing aperture or each yoke separating the fixing apertures.
Finally, the number of arms may be in particular 3, 4, 5 or 6.
The invention thus describes a wheel disc whose weight and method of manufacture are similar to those of a conventional steel disc optimised for a style approaching that of moulded or forged alloy discs.
The invention also has as a subject a wheel formed by the assembly of a rim and a disc according to the invention.
DESCRIPTION OF THE DRAWINGS
Wheel discs according to the invention will now be described by means of the attached drawing in which:
FIG. 1 is a perspective view of an assembled wheel having a disc according to the invention;
FIG. 2 is a view in axial section of the wheel of FIG. 1 along the axis of a fixing aperture;
FIGS. 3( a ) to 3 ( c ) show the development of the section of an arm of the center of the disc towards the exterior;
FIG. 4 is a view in section of the disc through the axes of two adjacent fixing apertures;
FIG. 5 is a perspective view of the internal face of the disc;
FIGS. 6 , 7 , 8 and 9 are enlargements of one of the fixing apertures of FIG. 5 and show four modified embodiments of the bearing faces; and
FIGS. 10 , 11 and 12 are partial views of FIG. 5 and show modified embodiments of the centering vent.
DESCRIPTION OF PREFERRED EMBODIMENTS
FIG. 1 shows a perspective view of the outer side (or external face) of an assembled wheel 1 having a disc 3 according to the invention and a rim 2 . FIG. 2 is an axial section of the same wheel through the axis of a fixing aperture. The rim 2 usually comprises two outer 24 and inner flanges 25 , two outer 22 and inner seats 23 , and a well 21 .
The disc 3 is manufactured by moulding, in particular embossing, from a sheet metal blank composed preferably of high-strength steel or aluminium. The essential components of the disc 3 are a radially outer circular assembling part 4 , a radially inner centering and fixing part 5 , and linking arms 6 between the parts 4 and 5 .
The part 4 is a assembling region with the rim 2 , as FIG. 2 shows, and the radially outer edge 41 of this assembling part 4 has a direction substantially parallel to the axis of rotation of the disc 3 . This assembling part 4 is circular, i.e. circumferentially continuous. Assembling on the rim 2 is usually effected by soldering. This may take place at the well 21 of the rim 2 . It is also possible to effect assembling under the outer seat 22 of the rim 2 .
The fixing and centering part 5 in this case has a bearing region 51 with five fixing apertures 52 and a radially inner edge curved axially outward in the form of a collar or centering vent 53 . The fixing apertures 52 are conceived to receive fixing bolts of the disc to a wheel hub of the vehicle. The internal face of the bearing region 51 has a bearing face 54 intended to come into contact with the hub of the vehicle. This bearing face 54 corresponds to the plane P. As FIG. 4 shows, with a section of the disc 3 between two adjacent fixing apertures 52 , the bearing region 51 as well as the bearing face 54 are interrupted between two fixing apertures by a yoke 55 . Preferably, the axial distance h between the plane P of the bearing face 54 and the inner face of the yoke 55 , in its central region, is greater than the thickness e of the starting sheet metal blank. This thickness e is between 3 and 6 mm according to the load that the wheel in question is to bear. Each yoke is defined by a bent portion of the piece of sheet metal and forms a generally concave side facing axially outwardly, and a generally convex side facing axially inwardly. An axially inner surface of the yoke is offset axially outwardly from the plane P.
The arms 6 connect the parts 4 and 5 and ensure the transmission of forces between these two parts of the disc 3 . The lateral edges of these arms 6 together with the radially inner edge of the assembling part 4 define large perforations 7 .
The problem of realising a wheel disc 3 having large perforations 7 is to make the arms 6 which laterally define these perforations sufficiently resistant to the fatigue stresses which arise during operation.
FIGS. 3( a ) to ( c ) show the development of the section of an arm 6 of the joining region with the fixing and centering part 5 towards the assembling part 4 . It can be seen that the section of these arms 6 substantially has an M shape. The M profile is obtained by two outer zones 63 with two lateral edges 61 and a pocket 64 disposed at the center of the arm with a floor 65 and two adjacent sides 66 . The two outer regions 63 form part of the outer face of the disc. In the embodiment in FIG. 1 , the pockets 64 have a generally oval shape and each include a bearing region 51 with a fixing aperture 52 . The side 66 surrounds part of the centering vent and thus completely surrounds the floor 65 , so that one could say the pockets are closed. The free edges of the cut-out 62 of the two lateral edges 61 of the arms 6 are folded down towards the inside of the disc, which completes the M profile. Preferably, the axially inwardly facing faces of the free edges of the cut-out 62 are also axially set back outwardly relative to the axially inwardly facing face of the floor 65 of the pocket 64 by a distance I, as is shown in FIGS. 3( a ) to 3 ( c ). The axial height of the reinforcement side 66 of the pocket 64 relative to the two outer regions 63 as well as the width of the floor 65 of the pocket 64 decrease progressively whereas the radial distance from the axis of the disc increases. This is shown in FIGS. 3( a ), 3 ( b ) and 3 ( c ).
In the example described, the assembly of the free edges of the cut-out of the arms 62 and the assembling part 42 all around the perforations 7 are folded down towards the internal face of the disc 3 . This makes it possible, in addition to lending additional rigidity, to increase the area of the perforations 7 and to give a more pleasing stylistic effect due to the disappearance of the areas where there are cut-outs, whose sharp ridges are not very attractive.
As the arms are subjected to high bending forces, the highest stresses during operation are concentrated on the external and internal faces of the disc. As the cut-out ridges are particularly sensitive to concentrations of stress, the fact that the folding back of the cut-out edges remains set back both with respect to the external and internal faces of the arms ensures that the stresses undergone by the cut-out ridges remain acceptable.
FIGS. 1 and 2 show that the adjacent outer regions 63 of two adjacent arms 6 join at the link with the fixing and centering part 5 and are extended in this part 5 by the yokes 55 as far as the vent 53 .
The fixing and centering region 5 is thus composed in the disc according to the invention of bearing regions 51 each surrounding a fixing aperture 52 , the adjacent bearing regions 51 being separated by yokes 55 as well as a centering vent 53 .
FIG. 5 shows a perspective view of the internal face of an embodiment of the disc 3 according to the invention. It shows in particular the fixing and centering part 5 having the five bearing regions 51 disposed around the five fixing apertures 52 , the five yokes 55 , and the centering vent 53 .
FIGS. 6 to 9 show four particular embodiments of the bearing faces 54 of the bearing regions 51 . FIG. 6 shows a first embodiment in which the bearing face 541 is unique and surrounds the fixing aperture 52 with only one interruption which is radially outward relative to the fixing aperture. In FIG. 7 , the bearing face is composed of two faces 542 disposed circumferentially on either side of the fixing aperture 52 . In FIG. 8 , the bearing face is composed of four faces 543 and 544 , two faces 543 disposed circumferentially on either side of and radially outward relative to the axis of the fixing aperture 52 and two faces 544 disposed circumferentially on either side of and radially inward relative to the axis of the fixing aperture 52 . The bearing face of FIG. 9 itself has three bearing faces, two faces 543 as above and one face 545 disposed radially inward relative to the axis of the fixing aperture 52 . The geometry of the bearing faces makes it possible to distribute the regions of concentration of stress in the bearing region and in the particular case of the disc 3 shown here, the embodiment in FIG. 9 is preferred.
The forces transmitted by the bending of one arm are thus borne simultaneously by the two radially upper bearing faces 543 , the radially inner bearing face 545 (or 544 ), but also by the bearing faces of the adjacent fixing apertures 52 via the yoke 55 /vent 53 torque.
FIGS. 10 , 11 and 12 show three particular embodiments of the geometry of the centering vent 53 . FIG. 10 shows the usual embodiment with a circular centering vent 531 . The assembly of the radially inner face is in contact with the centering lug of the vehicle wheel hub.
For matters of ease of industrial execution as well as precision of centering, it may be advantageous to provide preferred centering ranges. FIG. 11 shows a first preferred example. The centering vent 532 has five centering ranges 533 disposed to the right of the yokes 55 . In FIG. 12 , the centering vent 534 has five centering ranges 535 disposed to the right of the fixing apertures 52 .
Although the present invention has been described in connection with preferred embodiments thereof, it will be appreciated by those skilled in the art that additions, modifications, substitutions and deletions not specifically described may be made without departing from the spirit and scope of the invention as defined in the appended claims.
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Wheel disc, comprising a radially outer circular assembling part, a radially inner fixing and centering part with a bearing region comprising a given number of fixing apertures and ending radially inwardly with a centering vent, and arms connecting the inner and outer parts, each arm being disposed substantially opposite to one of the fixing apertures and the radially inner free edges of the radially outer circular part defining with the lateral free edges of the arms perforations, in which, in order to reinforce each arm mechanically, a pocket is housed, set back axially inwards relative to the outer face of the disc and in which a yoke connects each arm to the centering vent.
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[0001] This application claims priority to U.S. Provisional Patent Application No. 60/297,059, filed Jun. 8, 2001.
BACKGROUND OF THE INVENTION
[0002] The present invention is drawn to somatostatin-dopamine chimeric analogs.
[0003] Dopamine is a catecholamine neurotransmitter that has been implicated in the pathogenesis of both Parkinson disease and schizophrenia. Graybiel, et al., Adv. Neurol. 53, 17-29 (1990); Goldstein, et al., FASEB J. 6, 2413-2421 (1992); Olanow, et al., Annu. Rev. Neurosci. 22, 123-144 (1999). Egan, et al., Curr. Opin. Neurobiol. 7, 701-707 (1997). Dopamine and related molecules have been shown to inhibit the growth of several types of malignant tumors in mice, and this activity has been variously attributed to inhibition of tumor-cell proliferation, stimulation of tumor immunity or effects on melanin metabolism in malignant melanomas. Wick, M. M., J. Invest. Dermatol. 71, 163-164 (1978); Wick, M. M., J. Natl. Cancer Inst. 63, 1465-1467 (1979); Wick, M. M., Cancer Treat. Rep. 63, 991-997 (1979); Wick, M. M., Cancer Res. 40, 1414-1418 (1980); Wick, M. M., Cancer Treat. Rep. 65, 861-867 (1981); Wick, M. M. & Mui, J. Natl. Cancer Inst. 66, 351-354 (1981); Dasgupta, et al., J. Cancer Res. Clin. Oncol. 113, 363-368 (1987); Basu, et al., Endocrine 12, 237-241 (2000); Basu, et al., J. Neuroimmunol. 102, 113-124 (2000). Recent studies demonstrated the presence of D2 dopamine receptors on endothelial cells. Ricci, et al., J. Auton. Pharmacol., 14, 61-68 (1994); Bacic, et al., J. Neurochem. 57, 1774-1780 (1991). Dopamine has recently been reported to strongly and selectively inhibit at non-toxic levels the vascular permeabilizing and angiogenic activities of VPF/VEGF. Basu et al., Nat. Med. 7 (5), 569-574 (2001).
[0004] Somatostatin (SS), a tetradecapeptide discovered by Brazeau et al., has been shown to have potent inhibitory effects on various secretory processes in tissues such as pituitary, pancreas and gastrointestinal tract. SS also acts as a neuromodulator in the central nervous system. These biological effects of SS, all inhibitory in nature, are elicited through a series of G protein coupled receptors, of which five different subtypes have been characterized (SSTR1-SSTR5) (Reubi J C, et al., Cancer Res 47: 551-558, Reisine T, et al., Endocrine Review 16: 427-442, Lamberts S W, et al., Endocr Rev 12: 450-482, 4 Patel Y C, 1999 Front Neuroendocrinology 20: 157-198). These five subtypes have similar affinities for the endogenous SS ligands but have differing distribution in various tissues. Somatostatin binds to the five distinct receptor (SSTR) subtypes with relatively high and equal affinity for each subtype.
[0005] There is evidence that SS regulates cell proliferation by arresting cell growth via SSTR1, 2, 4, and 5 subtypes (Buscail L, et al., 1995 Proc Natl Acad Sci USA 92: 1580-1584; Buscail L, et al., 1994 Proc Natl Acad Sci USA 91: 2315-2319; Florio T, et al., 1999 Mol Endocrinol 13: 24-37; Sharma K, et al., 1999 Mol Endocrinol 13: 82-90), or by inducing apoptosis via SSTR3 subtype (Sharma K, et al., 1996 Mol Endocrinol 10: 1688-1696). SS and various analogues have been shown to inhibit normal and neoplastic cell proliferation in vitro and vivo (Lamberts S W, et al., Endocr Rev 12: 450-482) via specific SS receptors (SSTR's) (Patel Y C, 1999 Front Neuroendocrinology 20: 157-198) and possibly different postreceptor actions (Weckbecker G, et al., Pharmacol Ther 60: 245-264; Bell G I, Reisine T 1993 Trends Neurosci 16: 34-38; Patel Y C, et al., Biochem Biophys Res Commun 198: 605-612; Law S F, et al., Cell Signal 7:1-8). In addition, there is evidence that distinct SSTR subtypes are expressed in normal and neoplastic human tissues (9), conferring different tissue affinities for various SS analogues and variable clinical response to their therapeutic effects.
[0006] Binding to the different types of somatostatin receptor subtypes have been associated with the treatment of various conditions and/or diseases. (“SSTR2”) (Raynor, et al., Molecular Pharmacol. 43:838 (1993); Lloyd, et al., Am. J. Physiol. 268:G102 (1995)) while the inhibition of insulin has been attributed to the somatostatin type-5 receptor (“SSTR5”) (Coy, et al. 197:366-371 (1993)). Activation of types 2 and 5 have been associated with growth hormone suppression and more particularly GH secreting adenomas (Acromegaly) and TSH secreting adenomas. Activation of type 2 but not type 5 has been associated with treating prolactin secreting adenomas. Other indications associated with activation of the somatostatin receptor subtypes include inhibition of insulin and/or glucagon for treating diabetes mellitus, angiopathy, proliferative retinopathy, dawn phenomenon and nephropathy; inhibition of gastric acid secretion and more particularly peptic ulcers, enterocutaneous and pancreaticocutaneous fistula, irritable bowel syndrome, Dumping syndrome, watery diarrhea syndrome, AIDS related diarrhea, chemotherapy-induced diarrhea, acute or chronic pancreatitis and gastrointestinal hormone secreting tumors; treatment of cancer such as hepatoma; inhibition of angiogenesis; treatment of inflammatory disorders such as arthritis; retinopathy; chronic allograft rejection; angioplasty; preventing graft vessel and gastrointestinal bleeding. It is preferred to have an analog which is selective for the specific somatostatin receptor subtype or subtypes responsible for the desired biological response, thus, reducing interaction with other receptor subtypes which could lead to undesirable side effects.
[0007] Somatostatin (SS) and its receptors (SSTR1 to SSTR5) are expressed in normal human parafollicular C cells and medullary thyroid carcinoma (MTC). MTC is a tumor originating from thyroid parafollicular C cells that produces calcitonin (CT), somatostatin, as well as several other peptides (Moreau J P, et al., Metabolism 45 (8 Suppl 1): 24-26). Recently, Mato et al. showed that SS and SSTR's are expressed in human MTC (Mato E, et al., J Clin Endocrinol Metab 83: 2417-2420). It has been documented that SS and its analogues induce a decrease in plasma CT levels and a symptomatic improvement in MTC patients. However, until now the antiproliferative activity of SS analogues on tumor cells had not been clearly demonstrated (Mahler C, et al., Clin Endocrinol 33: 261-9; Lupoli G, et al., Cancer 78: 1114-8; Smid W M, et al., Neth J Med 40: 240-243). Thus, development and assessment of SSTR subtype analogues selective on MTC cell growth provides a useful tool for clinical application. Until now, no data concerning specific SSTR subtype involvement in MTC cell growth regulation have been reported.
SUMMARY OF THE INVENTION
[0008] The present invention is concerned with the discovery of a series of somatostatin-dopamine chimeric analogs that retain both somatostatin and dopamine activity in vivo, including several of which display enhanced biological activity over the native somatostatin and dopamine analogs alone, and the therapeutic uses thereof.
[0009] In one aspect the invention features a dopamine-somatostatin chimer of formula (I),
[0000]
[0000] wherein:
X is H, Cl, Br, I, F, —CN, or C 1-5 alkyl;
R1 is H, C 1-4 alkyl, allyl, alkenyl or —CN;
R2 and R3, each are, independently H or absent, provided that when R2 and R3 are absent a double bond is present between the carbon atoms to which they are attached;
R4 is H or —CH 3 ;
[0010] Y is —O—, —C(O)—, —S—, —S—(CH 2 )s-C(O)—, —S(O)—, —S(O) 2 —, —SC(O)—, —OC(O)—, —N(R5)-C(O)—, or —N(R6)-;
R5, R6, R7 and R8 each is, independently, H or C 1-5 alkyl;
R6 is H or C 1-5 alkyl;
m is 0 or 1;
n is 0-10;
L is —(CH 2 ) p —C(O)—, when Y is —S—, —S(O)—, —S(O) 2 —, —O— or —N(R6)-;
L is —C(O)—(CR7R8) q —C(O)—, when Y is —N(R6)-, —O—, or —S—;
L is -(Doc)t-, when Y is —C(O)—, SC(O)—, —OC(O)—, —S—(CH 2 )s-C(O)—, or —N(R5)-C(O)—;
p is 1-10;
q is 2-4;
s is 1-10;
t is 1-10; and
Z is somatostatin analog,
or a pharmaceutically acceptable salt thereof.
[0011] In another aspect the invention features a dopamine-somatostatin chimer of formula (II),
[0000]
[0000] wherein:
X is H, Cl, Br, I, F, —CN, or C 1-5 alkyl;
R1 is C 1-4 alkyl, H, allyl, alkenyl or —CN;
R2 and R3, each are, independently H or absent, provided that when R2 and R3 are absent a double bond is present between the carbon atoms to which they are attached;
R4 is H or —CH 3 ;
[0012] R5 is C 1-5 alkyl group, or a group of the formula of —(CH 2 )rN(CH 3 ) q ;
Y is —O—, —C(O)—, —S—, —SC(O)—, —OC(O)—, —N(R6)-C(O)—, —N(R7)-, or —N(R8)-(CH 2 )s-C(O)—;
R6, R7, R8, R9 and R10 each is, independently, H or C 1-5 alkyl;
L is —(CH 2 ) p —C(O)—, when Y is —S—, —O— or —N(R7)-;
L is —C(O)—(CR9R10) q —C(O)—, when Y is —N(R7)-, —O—, or —S—;
L is -(Doc)t-, when Y is —C(O)—, SC(O)—, —OC(O)—, —N(R8)-(CH 2 )s-C(O)—, or —N(R6)-C(O)—;
m is 0 or 1;
n is 2-10;
r is 1-8;
q is 2-4;
p is 1-10;
s is 1-10;
t is 1-10; and
Z is somatostatin analog
or a pharmaceutically acceptable salt thereof.
[0013] In one embodiment the invention features a compound according to the formula:
[0000]
[0000] Caeg=N-(2-aminoethyl)-N-(2-cytosinyl-1-oxo-ethyl)-glycine
[0000]
[0000] AEPA=4-(2-aminoethyl)-1-carboxymethyl-piperazine
[0000]
[0000] or a pharmaceutically acceptable salt thereof.
[0014] In another embodiment the invention features a compound according to the formula:
[0000]
[0000] or a pharmaceutically acceptable salt thereof.
[0015] In one aspect the invention features a method of eliciting a dopamine receptor agonist effect in a subject in need thereof, wherein said method comprises administering to said subject an effective amount of a compound according to formula (I) or formula (II), or a pharmaceutically acceptable salt thereof. In a preferred embodiment of this aspect the compound is selected from among the compounds specifically disclosed herein.
[0016] In another aspect the invention features a method of eliciting a somatostatin receptor agonist effect in a subject in need thereof, wherein said method comprises administering to said subject an effective amount of a compound according to formula (I) or formula (II), or a pharmaceutically acceptable salt thereof. In a preferred embodiment of this aspect the compound is selected from among the compounds specifically disclosed herein.
[0017] In another aspect the invention features a method of simultaneously eliciting both a dopamine receptor agonist effect and a somatostatin receptor agonist effect in a subject in need thereof, wherein said method comprises administering to said subject an effective amount of a compound according to formula (I) or formula (II), or a pharmaceutically acceptable salt thereof. In a preferred embodiment of this aspect the compound is selected from among the compounds specifically disclosed herein.
[0018] In another aspect the invention features a pharmaceutical composition comprising an effective amount of a compound according to formula (I) or formula (II), or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier. In a preferred embodiment of this aspect the compound is selected from among the compounds specifically disclosed herein.
[0019] In another aspect the invention features a method of treating a disease or condition in a subject, said method comprising administering to said subject a therapeutically effective amount of a compound of formula (I) or formula (II), or a pharmaceutically acceptable salt thereof, wherein said disease is selected from the list consisting of lung cancer, glioma, anorexia, hypothyroidism, hyperaldosteronism, H. pylori proliferation, acromegaly, restenosis, Crohn's disease, systemic sclerosis, external and internal pancreatic pseudocysts and ascites, VIPoma, nesidoblastosis, hyperinsulinism, gastrinoma, Zollinger-Ellison Syndrome, diarrhea, AIDS related diarrhea, chemotherapy related diarrhea, scleroderma, Irritable Bowel Syndrome, pancreatitis, small bowel obstruction, gastroesophageal reflux, duodenogastric reflux, Cushing's Syndrome, gonadotropinoma, hyperparathyroidism, Graves' Disease, diabetic neuropathy, Paget's disease, polycystic ovary disease, thyroid cancer, hepatome, leukemia, meningioma, cancer cachexia, orthostatic hypotension, postprandial hypotension, panic attacks, GH secreting adenomas, Acromegaly, TSH secreting adenomas, prolactin secreting adenomas, insulinoma, glucagonoma, diabetes mellitus, hyperlipidemia, insulin insensitivity, Syndrome X, angiopathy, proliferative retinopathy, dawn phenomenon, Nephropathy, gastric acid secretion, peptic ulcers, enterocutaneous fistula, pancreaticocutaneous fistula, Dumping syndrome, watery diarrhea syndrome, pancreatitis, gastrointestinal hormone secreting tumor, angiogenesis, arthritis, allograft rejection, graft vessel bleeding, portal hypertension, gastrointestinal bleeding, obesity, and opioid overdose. In a preferred embodiment of this aspect the compound is selected from among the compounds specifically disclosed herein. In a more preferred embodiment of this aspect of the invention said disease or condition is acromegaly.
[0020] In a particularly preferred embodiment of each of the foregoing methods the compound is selected from the list of compounds consisting of Compound A through Compound K, or from among the list of compounds consisting of Example L through Example V, as disclosed hereinbelow under the heading “Synthesis of Somatostatin-Dopamine Chimers”.
[0021] In another aspect of the invention is featured a dopamine agonist according the formula (I) or formula (II), hereinabove, wherein the somatostatin analog “z” is replaced by a moiety comprising —H, —OH, (C 1 -C 6 )alkoxy, arylalkoxy, (e.g., benzyl, substituted benzyl, and the like), —NH 2 , —NR9R10, where R9 and R10 are as defined in formula (II). In a preferred embodiment of this aspect said dopamine agonist is selected from among the dopamine moiety components of the dopamine-somatostatin chimers disclosed herein, or a pharmaceutically acceptable salt thereof. In a most preferred embodiment of this aspect said dopamine agonist is:
[0000]
[0000] or a pharmaceutically acceptable salt thereof.
DETAILED DESCRIPTION OF THE INVENTION
[0022] It is believed that one skilled in the art can, based on the description herein, utilise the present invention to its fullest extent. The following specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any was whatsoever.
[0023] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Also, all publications, patent applications, patents, and other references mentioned herein are incorporated by reference, each in its entirety.
[0024] Various somatostatin receptors (SSTR's) have been isolated, e.g., SSTR-1, SSTR-2, SSTR-3, SSTR-4, and SSTR-5. Thus, a somatostatin agonist may be one or more of an SSTR-1 agonist, SSTR-2 agonist, SSTR-3 agonist, SSTR-4 agonist or a SSTR-5 agonist. What is meant by, e.g., a somatostatin type-2 receptor agonist (i.e., SSTR-2 agonist) is a compound which has a high binding affinity (e.g., Ki of less than 100 nM, or preferably less than 10 nm, or more preferably less than 1 nM) for SSTR-2 (e.g., as defined by the receptor binding assay described below). What is meant by, e.g., a somatostatin type-2 receptor selective agonist is a somatostatin type-2 receptor agonist which has a higher binding affinity (i.e., lower Ki) for SSTR-2 than for any other somatostatin receptor.
[0025] In one embodiment the SSTR-2 agonist is also a SSTR-2 selective agonist. Examples of SSTR-2 agonists which may be used to practice the present invention include, but are not limited to:
D-NaI-cyclo[Cys-Tyr-D-Trp-Lys-Val-Cys]-Thr-NH 2 ; cyclo[Tic-Tyr-D-Trp-Lys-Abu-Phe]; 4-(2-Hydroxyethyl)-1-piperazinylacetyl-D-Phe-cyclo(Cys-Tyr-D-Trp-Lys-Abu-Cys)-Thr-NH 2 ; and 4-(2-Hydroxyethyl)-1-piperazine-2-ethanesulfonyl-D-Phe-cyclo(Cys-Tyr-D-Trp-Lys-Abu-Cys)-Thr-NH 2 .
[0030] Further examples of somatostatin agonists are those covered by formulae or those specifically recited in the publications set forth below, each of which is hereby incorporated by reference in its entirety.
[0031] EP Application No. P5 164 EU (Inventor: G. Keri);
[0032] Van Binst, G. et al. Peptide Research 5:8 (1992);
[0033] Horvath, A. et al. Abstract, “Conformations of Somatostatin Analogs Having Antitumor Activity”, 22nd European peptide Symposium, Sep. 13-19, 1992, Interlaken, Switzerland;
[0034] PCT Application No. WO 91/09056 (1991);
[0035] EP Application No. 0 363 589 A2 (1990);
[0036] U.S. Pat. No. 4,904,642 (1990);
[0037] U.S. Pat. No. 4,871,717 (1989);
[0038] U.S. Pat. No. 4,853,371 (1989);
[0039] U.S. Pat. No. 4,725,577 (1988);
[0040] U.S. Pat. No. 4,684,620 (1987);
[0041] U.S. Pat. No. 4,650,787 (1987);
[0042] U.S. Pat. No. 4,603,120 (1986);
[0043] U.S. Pat. No. 4,585,755 (1986);
[0044] EP Application No. 0 203 031 A2 (1986);
[0045] U.S. Pat. No. 4,522,813 (1985);
[0046] U.S. Pat. No. 4,486,415 (1984);
[0047] U.S. Pat. No. 4,485,101 (1984);
[0048] U.S. Pat. No. 4,435,385 (1984);
[0049] U.S. Pat. No. 4,395,403 (1983);
[0050] U.S. Pat. No. 4,369,179 (1983);
[0051] U.S. Pat. No. 4,360,516 (1982);
[0052] U.S. Pat. No. 4,358,439 (1982);
[0053] U.S. Pat. No. 4,328,214 (1982);
[0054] U.S. Pat. No. 4,316,890 (1982);
[0055] U.S. Pat. No. 4,310,518 (1982);
[0056] U.S. Pat. No. 4,291,022 (1981);
[0057] U.S. Pat. No. 4,238,481 (1980);
[0058] U.S. Pat. No. 4,235,886 (1980);
[0059] U.S. Pat. No. 4,224,199 (1980);
[0060] U.S. Pat. No. 4,211,693 (1980);
[0061] U.S. Pat. No. 4,190,648 (1980);
[0062] U.S. Pat. No. 4,146,612 (1979);
[0063] U.S. Pat. No. 4,133,782 (1979);
[0064] U.S. Pat. No. 5,506,339 (1996);
[0065] U.S. Pat. No. 4,261,885 (1981);
[0066] U.S. Pat. No. 4,728,638 (1988);
[0067] U.S. Pat. No. 4,282,143 (1981);
[0068] U.S. Pat. No. 4,215,039 (1980);
[0069] U.S. Pat. No. 4,209,426 (1980);
[0070] U.S. Pat. No. 4,190,575 (1980);
[0071] EP Patent No. 0 389 180 (1990);
[0072] EP Application No. 0 505 680 (1982);
[0073] EP Application No. 0 083 305 (1982);
[0074] EP Application No. 0 030 920 (1980);
[0075] PCT Application No. WO 88/05052 (1988);
[0076] PCT Application No. WO 90/12811 (1990);
[0077] PCT Application No. WO 97/01579 (1997);
[0078] PCT Application No. WO 91/18016 (1991);
[0079] U.K. Application No. GB 2,095,261 (1981); and
[0080] French Application No. FR 2,522,655 (1983).
[0081] Note that for all somatostatin agonists described herein, each amino acid residue represents the structure of —NH—C(R)H—CO—, in which R is the side chain (e.g., CH 3 for Ala). Lines between amino acid residues represent peptide bonds which join the amino acids. Also, where the amino acid residue is optically active, it is the L-form configuration that is intended unless D-form is expressly designated. For clarity, disulfide bonds (e.g., disulfide bridge) which exist between two free thiols of Cys residues are not shown. Abbreviations of the common amino acids are in accordance with IUPAC-IUB recommendations.
Synthesis of Somatostatin Agonists
[0082] The methods for synthesizing peptide somatostatin agonists are well documented and are within the ability of a person of ordinary skill in the art. For example, peptides are synthesized on Rink amide MBHA resin (4-(2′4′-dimethoxyphenyl-Fmoc-aminomethyl)-phenoxyacetamido-norleucyl-MBHA resin) using a standard solid phase protocol of Fmoc chemistry. The peptide-resin with free amino functional at the N-terminus is then treated with the corresponding compound containing dopamine moiety. The final product is cleaved off from resin with TFA/water/triisopropylsilane (TIS) mixture.
[0083] For example, synthesis of H-D-Phe-Phe-Phe-D-Trp-Lys-Thr-Phe-Thr-NH 2 , can be achieved by following the protocol set forth in Example I of European Patent Application 0 395 417 A1. The synthesis of somatostatin agonists with a substituted N-terminus can be achieved, for example, by following the protocol set forth in PCT Publication No. WO 88/02756, PCT Publication No. WO 94/04752, and/or European Patent Application No. 0 329 295.
[0084] Peptides can be and were cyclized by using iodine solution in MeOH/water and purified on C18 reverse-phase prep. HPLC, using acetonitrile-0.1% TFA/water-0.1% TFA buffers. Homogeneity was assessed by analytical HPLC and mass spectrometry and determined to be >95% for each peptide.
[0085] Certain uncommon amino acids were purchased from the following vendors: Fmoc-Doc-OH and Fmoc-AEPA were purchased from Chem-Impex International, Inc. (Wood Dale, Ill., USA). Fmoc-Caeg(Bhoc)-OH was purchased from PerSeptive Biosystems (Framingham Mass., USA). Bhoc stands for benzhydryloxycarbonyl.
Synthesis of Dopamine Agonists
[0086] The methods for synthesizing many dopamine agonists are also well documented and are within the ability of a person of ordinary skill in the art. Further synthetic procedures are provided in the following reaction schemes and examples.
[0000]
[0000]
[0000]
[0000]
[0000]
[0000]
[0000]
[0000]
[0000]
[0000]
[0000]
[0000]
[0000]
[0000]
[0000]
[0000]
[0000]
[0000]
[0000]
[0000]
[0000]
Synthesis of Somatostatin-Dopamine Chimers
[0087] The somatostatin-dopamine chimers may be synthesized according to the following reaction schemes and examples. Starting material and intermediates for compounds (I), (II) and (III), depicted in Scheme I, II, and III, respectively, are commercially available or prepared by the literatures; Pharmazie 39, 537 (1984); collect Czech. Chem. Commun. 33, (1966); Helv. Chim. Acta 32, 1947, (1949)’ U.S. Pat. No. 5,097,031; U.S. Pat. No. 3,901,894; EP 0003667; U.S. Pat. No. 4,526,892. The synthesis of peptides are within the scope of a skilled person in the art, and in any event, is readily available in the literature. See, e.g., Stewart et al., Solid Phase Synthesis, Pierce Chemical, 2 nd Ed. 1984; G. A. Grant; Synthetic peptide. WH., Freenand Co., New York, 1992; M. Bodenszky A. Bodanszky, The Practice of Peptide Synthesis. Spring Verlag. N.Y. 1984.
Preparation of Compound A:
[0088]
[0089] Compound 8 (3 eq.) is mixed with H-(Doc) 3 -D-Phe-Cys(Acm)-Tyr(tBu)-D-Trp(Boc)-Lys(Boc)-Abu-Cys(Acm)-Thr(tBu)-Rink amide MBHA resin (1 eq.), HBTU (2.9 eq), HOBt (3.0 eq.) and DIEA (6 eq) in DMF. The mixture is shaken at room temperature for 4 hours. The resin is washed with DMF and DCM and dried under reduced pressure to dryness. The dry resin is treated with TFA/TIS/water (92/5/3, v/v) for 1 hour at room temperature. The solution is filtered and concentrated. To the concentrated solution is added cold ether. The precipitate is collected and dissolved in water-methanol solvent system. To the solution is added iodine solution in methanol until the brown color appears. The solution then stands at room temperature for 1 hour. To the solution is added Na 2 S 2 O 3 aqueous solution until the brown color disappears. The resulting solution is purified by using a C18 reverse-phase prep HPLC, eluting with a linear gradient of buffer A (1% TFA in Water)/buffer B (1% TFA in CH 3 CN). The fractions are checked by analytical HPLC. The fractions containing pure desired compound are pooled and lyophilized to dryness. The molecular weight of the compound is measured by using MS fitted with an electrospray source.
Preparation of Compound B:
[0090]
[0091] Compound 12 where R1 is n-propyl (1.5 eq.) is mixed with H-D-Phe-Cys(Acm)-Tyr(tBu)-D-Trp(Boc)-Lys(Boc)-Abu-Cys(Acm)-Thr(tBu) Rink amide MBHA resin (1 eq) and DIEA (2 eq) in DMF. The mixture is shaken at room temperature for 5 hours. The resin is washed with DMF and DCM and dried under reduced pressure to dryness. The dry resin is treated with TFA/TIS/water (92/5/3, v/v) for 1 hour at room temperature. The solution is filtered and concentrated. To the concentrated solution is added cold ether. The precipitate is collected and dissolved in water-methanol solvent system. To the solution is added iodine solution in methanol until the brown color appears. The solution then stands at room temperature for 1 hour. To the solution is added Na 2 S 2 O 3 aqueous solution until the brown color disappears. The resulting solution is purified by using a C18 reverse-phase prep HPLC, eluting with a linear gradient of buffer A (1% TFA in Water)/buffer B (1% TFA in CH 3 CN). The fractions are checked by analytical HPLC. The fractions containing pure desired compound are pooled and lyophilized to dryness. The molecular weight of the compound is measured by using MS fitted with an electrospray source.
Preparation of Compound C:
[0092]
[0093] Compound 11 where R1 is n-propyl (1.5 eq.) is mixed with H-AEPA-D-Phe-Cys(Acm)-Tyr(tBu)-D-Trp(Boc)-Lys(Boc)-Abu-Cys(Acm)-Thr(tBu)-Rink amide MBHA resin (1 eq) and DIEA (2 eq) in DMF. The mixture is shaken at room temperature for 5 hours. The resin is washed with DMF and DCM and dried under reduced pressure to dryness. The dry resin is treated with TFA/TIS/water (92/5/3, v/v) for 1 hour at room temperature. The solution is filtered and concentrated. To the concentrated solution is added cold ether. The precipitate is collected and dissolved in water-methanol solvent system. To the solution is added iodine solution in methanol until the brown color appears. The solution then stands at room temperature for 1 hour. To the solution is added Na 2 S 2 O 3 aqueous solution until the brown color disappears. The resulting solution is purified by using a C18 reverse-phase prep HPLC, eluting with a linear gradient of buffer A (1% TFA in Water)/buffer B (1% TFA in CH 3 CN). The fractions are checked by analytical HPLC. The fractions containing pure desired compound are pooled and lyophilized to dryness. The molecular weight of the compound is measured by using MS fitted with an electrospray source.
Preparation of Compound D:
[0094]
[0095] Compound 25 (3 eq.) is mixed with H-Doc-D-Phe-Cys(Acm)-Tyr(tBu)-D-Trp(Boc)-Lys(Boc)-Abu-Cys(Acm)-Thr(tBu)-Rink amide MBHA resin (1 eq.), HBTU (2.9 eq), HOBt (3.0 eq.) and DIEA (6 eq) in DMF. The mixture is shaken at room temperature for 4 hours. The resin is washed with DMF and DCM and dried under reduced pressure to dryness. The dry resin is treated with TFA/TIS/water (92/5/3, v/v) for 1 hour at room temperature. The solution is filtered and concentrated. To it is added cold ether, the precipitate is collected and dissolved in water-methanol solvent system. To the solution is added iodine solution in methanol until the brown color appears. The solution is then stands at room temperature for 1 hour. To the solution is added Na 2 S 2 O 3 aqueous solution until the brown color disappears. The resulting solution is purified by using a C18 reverse-phase prep HPLC, eluting with a linear gradient of buffer A (1% TFA in Water)/buffer B (1% TFA in CH 3 CN). The fractions are checked by analytical HPLC. The fractions containing pure desired compound are pooled and lyophilized to dryness. The molecular weight of the compound is measured by using MS fitted with an electrospray source.
Preparation of Compound E:
[0096]
[0097] Compound 26 (3 eq.) is mixed with H-(D-Ser(tBu)) 5 -Lys(Boc)-D-Tyr(tBu)-D-Tyr(tBu)-Cys(Acm)-Tyr(tBu)-D-Trp(Boc)-Lys(Boc)-Val-Cys(Acm)-Trp(Boc)-Rink amide MBHA resin (1 eq.), HBTU (2.9 eq), HOBt (3.0 eq.) and DIEA (6 eq) in DMF. The mixture is shaken at room temperature for 4 hours. The resin is washed with DMF and DCM and dried under reduced pressure to dryness. The dry resin is treated with TFA/TIS/water (92/5/3, v/v) for 1 hour at room temperature. The solution is filtered and concentrated. To the concentrated solution is added cold ether. The precipitate is collected and dissolved in water-methanol solvent system. To the solution is added iodine solution in methanol until the brown color appears. The solution then stands at room temperature for 1 hour. To the solution is added Na 2 S 2 O 3 aqueous solution until the brown color disappears. The resulting solution is purified by using a C18 reverse-phase prep HPLC, eluting with a linear gradient of buffer A (1% TFA in Water)/buffer B (1% TFA in CH 3 CN). The fractions are checked by analytical HPLC. The fractions containing pure desired compound are pooled and lyophilized to dryness. The molecular weight of the compound is measured by using MS fitted with an electrospray source.
Preparation of Compound F:
Ethyl-[6-methyl-8β-ergolinylmethyl]thioacetate
[0098] To a solution of dihydrolysergol (240 mg) in 10 ml pyridine was added 250 μl methanesulfonyl chloride. After stirring at room temperature for 2 hours, the reaction mixture was poured into 100 ml water, it was extracted with chloroform (2×20 ml). Organic layer was washed with water, then dried over MgSO 4 and solvent was removed in vacuo to dryness to give 140 mg of pale brown solid. Further extraction from aqueous solution after basification with NaHCO 3 gave another 100 mg of product. Overall 240 mg. Mass Spec (Electrospray) 335.2.
[0099] To a solution of the above D-6-methyl-8β-mesyloxymethyl-ergoline (140 ng) in 3 ml dimethylformide was added powdered K 2 CO 3 (150 mg) followed by 150 μl ethyl-2-mercaptoacetate and the mixture was heated at 40° C. for 2 hours under nitrogen atmosphere. Solvent was removed in vacuo to dryness, and the residue partitioned between chloroform and water. Organic layer was then dried (MgSO 4 ), and after evaporation of solvent the residue was subject to preparative silica gel thin layer chromatography using chloroform/methanol (9:1) as developing solvents. Appropriate portion was isolated, extracted with chloroform-methanol and solvents were removed in vacuo to dryness. Pale brown solid. 100 mg Mass spec (Electrospray) 359.2.
Preparation of Compound G:
6-Methyl-8β-ergolinylmethylthioacetyl-D-Phe-c(Cys-Tyr-D-Trp-Lys-Abu-Cys)-Thr-NH 2
[0100] To a solution of 6-Methyl-8β-ergolinylmethylthioacetyl acid (Scheme I, compound 7) (50 mg) and D-Phe-c(Cys-Tyr(OBT)-D-Trp-Lys(BOC)-Abu-Cys)-Thr-NH 2 (100 mg) prepared by solid-phase synthesis using Fmoc-chemistry in 10 ml dimethylformide was added 200 mg of EDC (1-[3-(dimethylamino)-propyl]-3-ethylcarbodiimide-HCL), 100 mg of HOAT (1-Hydroxy-7-azabenzotriazole) followed by 200 μl diisopropylethylamine and the mixture was stirred at room temperature overnight. Volatile substances were removed in vacuo to dryness. The residue was partitioned between chloroform methanol and brine. The organic layer was washed with aqueous NaHCO 3 , dried over MgSO 4 . After evaporation of solvent, the residue was subject to preparative thin-layer chromatography using chloroform-methanol (85:15) as developing solvents. Appropriate portion was isolated, extracted with chloroform-methanol and solvents were removed in Vacuo to give 40 mg of protected product. Mass Spec. (Electrospray) 1500.7.
[0101] The protected product was then treated with 30% trifluoroacetic acid in dichloromethyl (10 ml) containing a few drops of triisopropyl silane for 30 minutes. Volatile substances were removed in vacuo to dryness. The residue was purified using vydac C 18 HPLC and CH 3 CN/0.1% aqueous TFA, resulting in 17 mg of white solid. Mass Spec (Electrospray). 1344.8, 673.2.
Preparation of Compound H:
Ethyl-(6-n-propyl-8β-ergolinyl)methylthioacetate
[0102] This compound was prepared analogously to Compound F, starting with D-n-propyl-8β-hydroxymethylergoline which can be made according to EP 000.667. Pale yellow solid. Mass Spec (Electrospray) 387.2.
[0000] Preparation of compound I:
6-n-propyl-8β-ergolinyl methylthioacetyl-D-Phe-c(Cys-Tyr-D-Trp-Lys-Abu-Cys)-Thr-NH 2
[0103] This compound was prepared analogously to Compound G, starting with 6-n-propyl-8β-ergolinyl)methylthioacetic acid (Scheme I, compound 6, where R1=propyl and s=1) and D-Phe-c(Cys-Tyr(OBT)-D-Trp-Lys(BOC)-Abu-Cys)-Thr-NH 2 . White solid. Mass Spec. (Electrospray) 1372.5, 687.3.
Preparation of Compound J:
6-D-Methyl-8β-ergolinylmethylthlaminosuccinoyl-D-Phe-c(Cys-Tyr-D-Trp-Lys-Abu-Cys)-Thr-NH 2
[0104] This compound was prepared analogously to Compound G starting with 6-D-Methyl-8β-succinoylaminomethylergoline and D-Phe-c(Cys-Tyr(OBT)-D-Trp-Lys(BOC)-Abu-Cys)-Thr-NH 2 , White solid. Mass Spec (Electrospray) 1344.8, 673.2.
Preparation of Compound K:
[0105] 6-allyl-8β-(1-ethyl-(3-N-methyl-3-carbonylmethyl)aminopropyl-ureidocarbonyl-ergoline-D-Phe-c(Cys-Tyr-D-Trp-Lys-Abu-Cys)-Thr-NH 2 , i.e., a compound according to the following structure:
[0000]
A. 1-[[6-allylergolin-8β-yl]carbonyl]-1-[3-(N-(ethoxycarbonyl)methyl,N-methyl)amino-propyl-3-ethylurea, i.e., a compound according to the following structure:
[0000]
(1) 3,3-BOC, N-Methylpropanediamine
[0107] To a solution of 3 N-Methyl propanediamine (1.8 g) in dichloromethane (30 ml) was added anhydrous MgSO4 (5.5 gm) followed by benzaldehyde (2.3 g) and the mixture was stirred at room temperature overnight. After filtration, the filtrate was treated with (BOC) 2 (4.3 g) and DMAP (0.35 g) and stirred for about 1 hour. The mixture was then washed with 5% aqueous citric acid, then 5% NaHCO 3 , and then dried over MgSO4.
[0108] After evaporation of solvent, the residue was dissolved in ethanol (50 ml). Pd(OH) 2 (600 mg), acetic acid (1 ml), and cyclohexene (3 ml) were added and hydrogenation was carried out overnight. The mixture was filtered through a celite pad and the filtrate was evaporated in vacuo to dryness to produce 3,3-BOC,N-Methylpropanediamine as a colorless liquid. 2.3 g. Mass Spec (Electrospray)=189.1.
(2) 6-allyl-8β-(3,3-BOC,N-Methyl-aminopropyl-carbamoyl)-ergoline
[0109] To a solution of 6-allyl-dihydrolysersic acid (150 mg), prepared according to the procedure disclosed in EP 0 003667, and 3,3-BOC,N-Methyl-propanediamine (150 mg) in DMF (5 ml) was added diisopropylethylamine (175 μl) followed by diethylcyanophosphonate (150 μl) and the mixture was stirred at room temperature overnight. Volatile substances were removed in vacuo to dryness. The residue was partitioned between CHCl 3 and water. The organic layer was then washed with aqueous NaHCO 3 and dried over MgSO 4 . Solvent was removed in vacuo to give 6-allyl-8β-(3,3-BOC,N-Methyl-aminopropyl-carbamoyl)-ergoline.
(3) 6-allyl-8β-(3-N-Methyl-aminopropyl-carbamoyl)-ergoline, TFA salt
[0110] 6-allyl-8β-(3,3-BOC,N-Methyl-aminopropyl-carbamoyl)-ergoline from the previous step was treated with 30% TFA in dichloromethane for 30 minutes and volatile substances were removed in vacuo to dryness yielding 250 mg of 6-allyl-8β-(3-N-Methyl-aminopropyl-carbamoyl)-ergoline, TFA salt. Mass spec (Electrospray)=367.2.
(4) 6-allyl-8β-(3-N-Methyl,3-carbethoxymethyl)aminopropyl-carbamoyl-ergoline
[0111] To a solution of 6-allyl-8β-(3-N-Methyl-aminopropyl-carbamoyl)-ergoline TFA salt (250 mg) and K 2 CO 3 (140 mg) in DMF (5 ml) was added ethyl bromoacetate (70111) and the mixture was stirred at room temperature overnight. After evaporation of solvent, the residue was partitioned between chloroform and water. The organic layer was dried using MgSO 4 and then solvent was removed in vacuo to give crude 6-allyl-8β-(3-N-Methyl,3-carbethoxymethyl)aminopropyl-carbamoyl-ergoline (240 mg). Mass Spec (Electrospray)=453.2.
(5) 6-allyl-8β-(1-ethyl-(3-N-methyl-3-carbethoxymethyl)aminopropyl-ureidocarbonyl-ergoline
[0112] 6-allyl-8β-(3-N-Methyl,3-carbethoxymethyl)aminopropyl-carbamoyl-ergoline from the previous step was dissolved in toluene (10 ml) and ethylisocyanate (3 ml) was added. The mixture was refluxed under nitrogen atmosphere for 3 days and after evaporation of volatile substances, the residue was subject to preparative silica gel chromatography using chloroform/methanol (19 to 1) as developing solvents. Appropriate portion was extracted with chloroform/methanol and solvents were removed in vacuo to give 6-allyl-8β-(1-ethyl-(3-N-methyl-3-carbethoxymethyl)aminopropyl-ureidocarbonyl-ergoline as a pale yellow viscous substance (30 mg). Mass Spec (Electrospray)=524.3.
B. 6-allyl-8β-(1-ethyl-(3-N-methyl-3-carboxymethyl)aminopropyl-ureidocarbonyl-ergoline, i.e., a compound according to the following structure:
[0000]
[0114] To a mixture of 6-allyl-8β-(1-ethyl-(3-N-methyl-3-carbethoxymethyl)aminopropyl-ureidocarbonyl-ergoline (520 mg) in 10 ml of acetone are added 15 ml of 0.2M phosphate buffer (pH=approx. 7) and 0.6 ml ChiroCLEC-BL (Altus Biologics, Cambridge, Mass.). The mixture is incubated on a rotary shaker at approximately 40 C overnight. The mixture is acidified with 5% aqueous citric acid and extracted with CHCl 3 -Methanol. The organic extract is dried and the solvents are removed in vacuo to yield 6-allyl-8β-(1-ethyl-(3-N-methyl-3-carboxymethyl)aminopropyl-ureidocarbonyl-ergoline.
C. 6-allyl-8β-(1-ethyl-(3-N-methyl-3-carbonylmethyl)aminopropyl-ureidocarbonyl-ergoline-D-Phe-c(Cys-Tyr-D-Trp-Lys-Abu-Cys)-Thr-NH 2 , i.e., Compound K
[0116] To a solution of 6-allyl-8β-(1-ethyl-(3-N-methyl-3-carboxymethyl)aminopropyl-ureidocarbonyl-ergoline (50 mg) and D-Phe-c(Cys-Tyr-D-Trp-Lys(FMOC)-Abu-Cys)-Thr-NH 2 (100 mg, prepared by solid-phase synthesis), in 10 ml dimethylformide is added 200 mg of EDC (1-[3-(dimethylamino)-propyl]-3-ethylcarbodiimide-HCL), 100 mg of HOAT (1-Hydroxy-7-azabenzotriazole) followed by 200 μl diisopropylethylamine and the mixture is stirred at room temperature overnight. Volatile substances are removed in vacuo to dryness. The residue is partitioned between chloroform methanol and brine. The organic layer is washed with aqueous NaHCO 3 and then dried over MgSO 4 . After evaporation of solvent the protected product is then treated with 5% piperidine in DMF (10 ml) for 30 minutes. Volatile substances are removed in vacuo to a small volume (about 2 ml). It is purified using VYDAC C 18 HPLC and CH 3 CN/0.1% aqueous TFA to yield the purified, de-protected product.
Example L
[0117]
[0118] A. H-Aepa-Lys(Boc)-DTyr(tBu)-DTyr(tBu)-Cys(Trt)-Tyr(tBu)-DTrp(Boc)-Lys(Boc)-Abu-Cys(Trt)-Thr(tBu)-Rink Amide MBHA Resin
[0000] The protected peptide-resin was automatically synthesized on an Applied Biosystems (Foster City, Calif.) model 433A peptide synthesizer by using Fluorenylmethyloxycarbonyl (Fmoc) chemistry. A Rink Amide MBHA resin (Novabiochem., San Diego, Calif.) with substitution of 0.72 mmol/g was used. The Fmoc amino acids (AnaSpec, San Jose, Calif.) were used with the following side chain protection: Fmoc-Thr(tBu)-OH, Fmoc-Cys(Trt)-OH, Fmoc-Lys(Boc)-OH, Fmoc-DTrp(Boc)-OH, Fmoc-Tyr(tBu)-OH, Fmoc-DTyr(tBu)-OH Fmoc-Phe-OH, Fmoc-Cys(Trt)-OH, Fmoc-Thr(tBu)-OH and Fmoc-Abu-OH. Fmoc-Aepa-OH was purchased from Chem-Impex International, Inc. (Wood Dale, Ill.). The synthesis was carried out on a 0.25 mmol scale. The Fmoc groups were removed by treatment with 20% piperidine in N-methylpyrrolidone (NMP) for 30 min. In each coupling step, the Fmoc amino acid (4 eq, 1 mmol) was first pre-activated in 2 mL solution of 0.45M 2-(1-H-benzotriazole-1-yl)-1,1,2,3-tetramethyluronium hexafluorophosphate/1-hydroxy-benzotriazole (HBTU/HOBT) in N,N-dimethylformamide (DMF). This activated amino acid ester, 1 mL of diisopropylethylamine (DIEA) and 1 mL of NMP were added to the resin. The ABI 433A peptide synthesizer was programmed to perform the following reaction cycle: (1) washing with NMP, (2) removing Fmoc protecting group with 20% piperidine in NMP for 30 min, (3) washing with NMP, (4) coupling with pre-activated Fmoc amino acid for 1 h. The resin was coupled successively according to the sequence. After peptide chain was assembled, the Fmoc was removed and washed completely by using DMF and dichloromethane (DCM).
MBHA=4-methylbenzylhydrylamine
Aepa=
[0119]
[0120] B. The resulting H-Aepa-Lys(Boc)-DTyr(tBu)-DTyr(tBu)-Cys(Trt)-Tyr(tBu)-DTrp(Boc)-Lys(Boc)-Abu-Cys(Trt)-Thr(tBu)-Rink Amide MBHA Resin (0.188 mmol) was mixed with compound 7 (92 mg, 0.28 mmol, 1.5 eq.), [7-azabenzotriazol-1-yloxytris(pyrrolidino)phosphonium-hexafluorophosphate] (PyAOP) (146 mg, 0.28 mmol, 1.5 eq.) and 1-hydroxy-7-azabenzotriazol (HOAT) (38 mg, 0.28 mmol, 1.5 eq.) in 5 mL of DCM. The mixture was shaken overnight. The resin was drained and washed successively with DMF, methanol and DCM. After drying in the air, the resin was treated with a mixture of TFA, H 2 O and triisopropylsilane (TIS) (9.5 ml/0.85 ml/0.8 ml) for 2 h. The resin was filtered off and the filtrate was poured into 50 mL of cold ether. The precipitate was collected after centrifuge. The crude product was dissolved in 100 ml of 5% AcOH aqueous solution, to which iodine methanol solution was added dropwise until yellow color maintained. The reaction solution was stirred for additional 1 h. 10% Na 2 S 2 O 3 water solution was added to quench excess iodine. The crude product in the solution was purified on preparative HPLC system with a column (4×43 cm) of C18 DYNAMAX-100 A 0 (Varian, Walnut Creek, Calif.). The column was eluted with a linear gradient from 80% A and 20% B to 55% A and 45% B in 50 min., where A was 0.1% TFA in water and B was 0.1% TFA in acetonitrile. The fractions were checked by an analytical HPLC. Those containing pure product were pooled and lyophilized to dryness. Yield: 40%. The purity was 96.8% based on analytical HPLC analysis. MS (Electro Spray): 1820.8 (in agreement with the calculated molecular weight of 1821.3).
Example M
[0121]
[0122] Example M was synthesized substantially according to the procedure described for Example L by using H-Lys(Boc)-DTyr(tBu)-DTyr(tBu)-Cys(Trt)-Tyr(tBu)-DTrp(Boc)-Lys(Boc)-Abu-Cys(Trt)-Thr(tBu)-Rink Amide MBHA Resin. Purity of the final product was 97.9% based on analytical HPLC analysis. MS (Electro Spray): 1652.1 (in agreement with the calculated molecular weight of 1652.03).
Example N
[0123]
[0124] Example N was synthesized substantially according to the procedure described for Example L by using H-Doc-Lys(Boc)-DTyr(tBu)-DTyr(tBu)-Cys(Trt)-Tyr(tBu)-DTrp(Boc)-Lys(Boc)-Abu-Cys(Trt)-Thr(tBu)-Rink Amide MBHA Resin. Purity of the final product was 99.2% based on analytical HPLC analysis. MS (Electro Spray): 1797.1 (in agreement with the calculated molecular weight of 1797.19).
[0000] Fmoc-Doc-OH was purchased from Chem-Impex International, Inc. (Wood Dale, Ill.).
[0000]
[0125] Doc=
Example O
[0126]
[0127] Example O was synthesized substantially according to the procedure described for Example L by using (6-N-propyl-8β-ergolinyl)methylthioacetic acid and H-Lys(Boc)-DTyr(tBu)-DTyr(tBu)-Cys(Trt)-Tyr(tBu)-DTrp(Boc)-Lys(Boc)-Abu-Cys(Trt)-Thr(tBu)-Rink Amide MBHA Resin. Purity of the final product was 97.4% based on analytical HPLC analysis. MS (Electro Spray): 1680.6 (in agreement with the calculated molecular weight of 1680.1).
Example P
[0128]
[0129] Example P was synthesized substantially according to the procedure described for Example L by using (6-N-propyl-8β-ergolinyl)methylthioacetic acid and H-Aepa-Aepa-D-Phe-Cys(Trt)-Tyr(tBu)-DTrp(Boc)-Lys(Boc)-Abu-Cys(Trt)-Thr(tBu)-Rink Amide MBHA Resin. Purity of the final product was 99.9% based on analytical HPLC analysis. MS (Electro Spray): 1710.7 (in agreement with the calculated molecular weight of 1711.2).
Example Q
[0130]
[0131] Example Q was synthesized substantially according to the procedure described for Example L by using (6-N-propyl-8β-ergolinyl)methylthioacetic acid and H-Aepa-Aepa-DPhe-Cys(Trt)-(3-Iodo)Tyr-DTrp(Boc)-Lys(Boc)-Val-Cys(Trt)-Thr(tBu)-Rink Amide MBHA Resin. Purity of the final product was 99% based on analytical HPLC analysis. MS (Electro Spray): 1851.1 (in agreement with the calculated molecular weight of 1851.1). Fmoc-(3-Iodo)-Tyr-OH was purchased from Advanced ChemTech (Louisville, Ky.).
(3-Iodo)Tyr=
[0132]
Example R
[0133]
[0134] Example R was synthesized substantially according to the procedure described for Example L by using H-Aepa-DPhe-Cys(Trt)-Tyr(tBu)-DTrp(Boc)-Lys(Boc)-Abu-Cys(Trt)-Thr(tBu)-Rink Amide MBHA Resin. Purity of the final product was 98.3% based on analytical HPLC analysis. MS (Electro Spray): 1513.8 (in agreement with the calculated molecular weight of 1513.9).
Example S
[0135]
[0136] Example S was synthesized substantially according to the procedure described for Example L by using H-Aepa-Aepa-DPhe-Cys(Trt)-(3-Iodo)Tyr-DTrp(Boc)-Lys(Boc)-Val-Cys(Trt)-Thr(tBu)-Rink Amide MBHA Resin. Purity of the final product was 85.7% based on analytical HPLC analysis. MS (Electro Spray): 1822.9 (in agreement with the calculated molecular weight of 1823.06).
Example T
[0137]
[0138] Example T was synthesized substantially according to the procedure described for Example L by using H-Doc-DPhe-Cys(Trt)-Tyr(tBu)-DTrp(Boc)-Lys(Boc)-Abu-Cys(Trt)-Thr(tBu)-Rink Amide MBHA Resin. Purity of the final product was 98.9% based on analytical HPLC analysis. MS (Electro Spray): 1489.6 (in agreement with the calculated molecular weight of 1489.84).
Example U
[0139]
[0140] Example U was synthesized substantially according to the procedure described for Example L by using H-Doc-DPhe-Cys(Trt)-(3-Iodo)Tyr-DTrp(Boc)-Lys(Boc)-Val-Cys(Trt)-Thr(tBu)-Rink Amide MBHA Resin. MS (Electro Spray): 1629.8 (in agreement with the calculated molecular weight of 1629.7).
Example V
[0141]
[0142] The titled compound was synthesized substantially according to the procedure described for Example L by using H-Doc-Doc-DPhe-Cys(Trt)-Tyr(tBu)-DTrp(Boc)-Lys(Boc)-Abu-Cys(Trt)-Thr(tBu)-Rink Amide MBHA Resin. Purity of the final product was 99% based on analytical HPLC analysis. MS (Electro Spray): 1635.0 (in agreement with the calculated molecular weight of 1633).
[0143] Some of the compounds of the instant invention can have at least one asymmetric center. Additional asymmetric centers may be present on the molecule depending upon the nature of the various substituents on the molecule. Each such asymmetric center will produce two optical isomers and it is intended that all such optical isomers, as separated, pure or partially purified optical isomers, racemic mixtures or diastereomeric mixtures thereof, are included within the scope of the instant invention.
[0144] The compounds of the instant invention generally can be isolated in the form of their pharmaceutically acceptable acid addition salts, such as the salts derived from using inorganic and organic acids. Examples of such acids are hydrochloric, nitric, sulfuric, phosphoric, formic, acetic, trifluoroacetic, propionic, maleic, succinic, D-tartaric, L-tartaric, malonic, methane sulfonic and the like. In addition, certain compounds containing an acidic function such as a carboxy can be isolated in the form of their inorganic salt in which the counter-ion can be selected from sodium, potassium, lithium, calcium, magnesium and the like, as well as from organic bases.
[0145] The pharmaceutically acceptable salts can be formed by taking about 1 equivalent of a compound of the invention, (e.g., Compound C, below), and contacting it with about 1 equivalent or more of the appropriate corresponding acid of the salt which is desired. Work-up and isolation of the resulting salt is well-known to those of ordinary skill in the art.
[0146] The compounds of this invention can be administered by oral, parenteral (e.g., intramuscular, intraperitoneal, intravenous or subcutaneous injection, or implant), nasal, vaginal, rectal, sublingual or topical routes of administration and can be formulated with pharmaceutically acceptable carriers to provide dosage forms appropriate for each route of administration. Accordingly, the present invention includes within its scope pharmaceutical compositions comprising, as an active ingredient, at least one compound of the invention in association with a pharmaceutically acceptable carrier.
[0147] Solid dosage forms for oral administration include capsules, tablets, pills, powders and granules. In such solid dosage forms, the active compound is admixed with at least one inert pharmaceutically acceptable carrier such as sucrose, lactose, or starch. Such dosage forms can also comprise, as is normal practice, additional substances other than such inert diluents, e.g., lubricating agents such as magnesium stearate. In the case of capsules, tablets and pills, the dosage forms may also comprise buffering agents. Tablets and pills can additionally be prepared with enteric coatings.
[0148] Liquid dosage forms for oral administration include pharmaceutically acceptable emulsions, solutions, suspensions, syrups, the elixirs containing inert diluents commonly used in the art, such as water. Besides such inert diluents, compositions can also include adjuvants, such as wetting agents, emulsifying and suspending agents, and sweetening, flavoring and perfuming agents.
[0149] Preparations according to this invention for parenteral administration include sterile aqueous or non-aqueous solutions, suspensions, or emulsions. Examples of non-aqueous solvents or vehicles are propylene glycol, polyethylene glycol, vegetable oils, such as olive oil and corn oil, gelatin, and injectable organic esters such as ethyl oleate. Such dosage forms may also contain adjuvants such as preserving, wetting, emulsifying, and dispersing agents. They may be sterilized by, for example, filtration through a bacteria-retaining filter, by incorporating sterilizing agents into the compositions, by irradiating the compositions, or by heating the compositions. They can also be manufactured in the form of sterile solid compositions which can be dissolved in sterile water, or some other sterile injectable medium immediately before use.
[0150] Compositions for rectal or vaginal administration are preferably suppositories which may contain, in addition to the active substance, excipients such as coca butter or a suppository wax.
[0151] Compositions for nasal or sublingual administration are also prepared with standard excipients well known in the art.
[0152] In general, an effective dosage of active ingredient in the compositions of this invention may be varied; however, it is necessary that the amount of the active ingredient be such that a suitable dosage form is obtained. The selected dosage depends upon the desired therapeutic effect, on the route of administration, and on the duration of the treatment, all of which are within the realm of knowledge of one of ordinary skill in the art. Generally, dosage levels of between 0.0001 to 100 mg/kg of body weight daily are administered to humans and other animals, e.g., mammals.
[0153] A preferred dosage range is 0.01 to 10.0 mg/kg of body weight daily, which can be administered as a single dose or divided into multiple doses.
Somatostatin Receptor Specificity and Selectivity Assay
[0154] Specificity and selectivity of the somatostatin analogues used to synthesize the somatostatin-dopamine chimers were determined by a radioligand binding assay on CHO-K1 cells stably transfected with each of the SSTR subtypes, as follows.
[0155] The complete coding sequences of genomic fragments of the SSTR 1, 2, 3, and 4 genes and a cDNA clone for SSTR 5 were subcloned into the mammalian expression vector pCMV (Life Technologies, Milano, Italy). Clonal cell lines stably expressing SSTR's 1-5 were obtained by transfection into CHO-K1 cells (ATCC, Manassas, Va., USA) using the calcium phosphate co-precipitation method (Davis L, et al., 1994 In: Basic methods in Molecular Biology, 2nd edition, Appleton & Lange, Norwalk, Conn., USA: 611-646). The plasmid pRSV-neo (ATCC) was included as a selectable marker. Clonal cell lines were selected in RPMI 1640 media containing 0.5 mg/ml of G418 (Life Technologies, Milano, Italy), ring cloned, and expanded into culture.
[0156] Membranes for in vitro receptor binding assays were obtained by homogenizing the CHO-K1 cells expressing the SSTR's subtypes in ice-cold 50 mM Tris-HCl and centrifuging twice at 39000 g (10 min), with an intermediate resuspension in fresh buffer. The final pellets were resuspended in 10 mM Tris-HCl for assay. For the SSTR 1, 3, 4, and 5 assays, aliquots of the membrane preparations were incubated 90 min. at 25° C. with 0.05 nM [ 125 I-Tyr11]SS-14 in 50 mM HEPES (pH 7.4) containing 10 mg/ml BSA, 5 mM MgCl 2 , 200 KIU/ml Trasylol, 0.02 mg/ml bacitracin, and 0.02 mg/ml phenylmethylsuphonyl fluoride. The final assay volume was 0.3 ml. For the SSTR 2 assay, 0.05 nM [ 125 I]MK-678 was employed as the radioligand and the incubation time was 90 min at 25° C. The incubations were terminated by rapid filtration through GF/C filters (pre-soaked in 0.3% polyethylenimine) using a Brandel filtration manifold. Each tube and filter were then washed three times with 5 ml aliquots of ice-cold buffer. Specific binding was defined as the total radioligand bound minus that bound in the presence of 1000 nM SS-14 for SSTR 1, 3, 4, and 5, or 1000 nM MK-678 for SSTR2.
[0157] Dopamine Receptor Specificity and Selectivity Assay Specificity and selectivity for the dopamine-2 receptor of the dopamine analogues used to synthesize the somatostatin-dopamine chimers may be determined by a radioligand binding assay as follows.
[0158] Crude membranes were prepared by homogenization of frozen rat corpus striatum (Zivic Laboratories, Pittsburgh, Pa.) in 20 ml of ice-cold 50 mM Tris-HCl with a Brinkman Polytron (setting 6, 15 sec). Buffer was added to obtain a final volume of 40 ml, and the homogenate was centrifuged in a Sorval SS-34 rotor at 39,000 g for 10 min at 0-4° C. The resulting supernatant was decanted and discarded. The pellet was rehomogenized in ice-cold buffer, pre-incubated at 37° C. for 10 min, diluted, and centrifuged as before. The final pellet was resuspended in buffer and held on ice for the receptor binding assay.
[0159] For assay, aliquots of the washed membrane preparations and test compounds were incubated for 15 min (37 C) with 0.25 nM [ 3 HI]spiperone (16.5 Ci.mmol, New England Nuclear, Boston, Mass.) in 50 mM Tris HCl, 120 mM NaCl, 5 mM KCl, 2 mM CaCl2, 1 mM MgCl2. The final assay volume was 1.0 ml. The incubations were terminated by rapid filtration through GF/B filters using a Brandel filtration manifold. Each tube and filter were then washed three times with 5-ml aliquots of ice-cold buffer. Specific binding was defined as the total radioligand bound minus that bound in the presence of 1000 nM (+) butaclamol.
Other Embodiments
[0160] It is to be understood that while the invention has been described in conjunction with the detailed description thereof, that the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the claims. Also, all publications mentioned herein are hereby incorporated by reference in their entirety.
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Disclosed is a series of somatostatin-dopamine chimeric analogs which retain both somatostatin and dopamine activity in vivo. An example is:
6-n-propyl-8β-ergolinglmethylthioacetyl-D-Phe-c(Cys-Tyr-D-Trp-Lys-Abu-Cys)-Thr-NH 2
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FIELD OF THE INVENTION
[0001] The present invention relates generally to a multiple zone control system for controlling heating and/or air conditioning and a method of operation thereof. In particular, the invention is directed to the control and operation of multiple heating (cooling) zones for single and multiple family residences.
BACKGROUND OF THE INVENTION
[0002] Boiler systems have been used to regulate the temperature of commercial and residential facilities for a number of years. However, despite the fact that boiler systems have been around for many years, innovations continue to change the manner in which these systems operate.
[0003] The first residential boilers were coal or wood fired and were always “on”. The resulting over or under heating was corrected by opening a window, putting on a sweater and adding more or less fuel the next day. Next the industry introduced the “on/off” boiler that turned “on” the boiler when the home was cold and turned it “off” after it became warm. A single thermostat sensed room temperature at a single home position. The remainder of the home was either cooler or warmer as a result. To solve this issue the industry introduced multiple heating zones. This provided individual rooms or groups of rooms with separate thermostats and heated water was only circulated to where it was needed. This innovation greatly improved home comfort, however, it sometimes lead to a dramatically over sized heat source for when a small zone calls for heat. The result was potentially excessive boiler cycling. Boiler cycles add wear and tear on boiler, reduce equipment life and waste energy. They also lead to less home comfort as warm water is not consistently supplied. To address this issue the industry introduced the modulating boiler. This boiler could reduce British thermal unit (BTU) output when the demand was from a smaller zone.
[0004] However, modulating boilers could only use water temperature feedback to modulate the firing rate. When water temperature is below setpoint the firing rate is increased to heat water and increase water temperature until it matches the setpoint. This method is aware of the amount of heat loss (heating load) only after sensing the temperature and the rate of temperature change. This method allows the system to overshoot and/or excessively cycle as cold return water drives the firing rate to maximum modulation even if only a small zone is calling. This problem is increased by the fact that boilers are not sized (selected and installed) to match the active load. Boilers actually cannot be sized to match the active load. Boilers are sized to meet the total home heat demand on a design day. Typical condensing boiler installations have four water zones. When only one zone is calling for heat the boiler is dramatically oversized for that demand. As a result, the boiler first senses a low boiler supply temperature and fires the boiler as if the entire home was calling. This initial response produces unneeded and potentially excessive cycles.
[0005] It would be beneficial to provide a multiple zone control system for controlling heating and/or air conditioning and a method of operation thereof which is efficient and which eliminates excessive wear and cycle of the heating/cooling unit.
SUMMARY OF THE INVENTION
[0006] An object of the invention is to provide a means to detect active (turned “on”) zones, totals BTUs required and sets the heating/cooling firing rate to “match” actual home demand.
[0007] An object of the invention is to provide a heating/cooling system which is able to satisfy each individual zone with the appropriate amount of heat/cooling without extra cycles, component life reduction or wasted energy.
[0008] An object of the invention is to provide adaptive firing rate control. This type of control adds feed-forward to the conventional temperature based feedback control system. This control device calculates the boiler size required based on the particular zone that is calling, a control technique called “feed-forward” control. Before the boiler is even released to fire the boiler, “size” is set to match the possible heat loss. Temperature modulation is then used to adjust this firing rate further to suit the active load. The control device optimizes condensing boiler firing rate by preventing the firing rate from driving too high based on measuring temperature alone. The result is a significantly increased amount of time the boiler operates in the condensing mode, reduced cycling, increasing equipment life and saving fuel.
[0009] An embodiment is directed to a multiple heating zone control system in which a boiler or stage is provided with heating BTU/hr capacity required and water temperatures required. A heating system control device continuously monitors heating zone demand and matches the boiler output capacity to the total space or indirect water heater heat input required. Within the calculated boiler output capacity the boiler is modulated based on zone water temperature setpoint to further adjust boiler heat output. As heat loss is increased boiler capacity and modulation are increased. Should heat loss decrease, boiler capacity and modulation are decreased. Hence, the overall effect of the control device is a reduction in boiler cycles, extended boiler life and subsequent energy savings.
[0010] An embodiment is directed to a method for controlling a multiple zoned heating/cooling system. The method includes: establishing a heating/cooling demand for individual zones; communicating to a controller active zones of the multiple zoned heating/cooling system which require heating/cooling; summing the total heating/cooling demand required by the active zones; establishing a maximum heating/cooling rate based on the total heating/cooling demand required by the active zones; establishing the type of heating/cooling radiation type associated with heating/cooling demand; communicating to the controller active heating/cooling radiation type; establishing a target temperature setpoint based on active heating/cooling radiation type; and setting a heating/cooling rate based on measured temperature, target temperature setpoint and a maximum heating/cooling rate.
[0011] An embodiment is directed to a method for controlling a multiple zoned boiler heating system. The method includes: establishing the heating demand for an amount of hot water flowing or for individual heating zones; establishing a maximum firing rate based on the total heating demand; setting the firing rate based on measured temperature, the target water temperature setpoint and the maximum firing rate.
[0012] An embodiment is directed to a boiler control system. The boiler system includes at least one zone panel with thermostats connected thereto, with individual thermostats monitoring individual zones. A boiler controller communicates with a boiler to control the operation of the boiler. A communication bus extends between the at least one zone panel and the boiler controller. The boiler controller receives information from the at least one zone controller and sums the total heating demand required by the individual zones which require heat. The boiler controller sets the water temperature setpoint for the boiler and the firing rate for the boiler based measured water temperature, target temperature setpoint and the total heating demand required by the active zones.
[0013] Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a diagrammatic schematic view of an illustrative multi-zoned heating system according to the present invention.
[0015] FIG. 2 is a diagrammatic view of an illustrative embodiment of zone panels and the boiler controller according to the present invention.
[0016] FIG. 3 is a diagrammatic view of an illustrative embodiment of the system control logic according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0017] The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. In the drawings, the relative sizes of regions or features may be exaggerated for clarity. 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 thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
[0018] It will be understood that spatially relative terms, such as “top”, “upper”, “lower” and the like, may be used herein for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “over” other elements or features would then be oriented “under” the other elements or features. Thus, the exemplary term “over” can encompass both an orientation of over and under. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
[0019] The present invention is directed to a system and method for controlling heating and/or air conditioning which receives input from multiple zones. The system includes multiple zones with control inputs for receiving signals from individual thermostats to sense individual zone demand. The system also includes control outputs to provide heating or cooling to individual zones, i.e. turn on water flow to individual zones.
[0020] Referring to FIG. 1 , an illustrative multiple zoned heating system 10 is shown. While the present invention is not limited to multi-zoned heating systems, a multi-zoned heating system is used for illustration. The system shown in FIG. 1 is used to control the temperature in an enclosure 11 in which a first zone 12 and a second zone 14 have been defined. While the illustrative embodiment depicts two zones, additional zones may be provided, including but not limited to, sixteen (16) total zones.
[0021] The system includes a boiler controller 20 which controls at least one boiler 21 and separate zone controller/panel 22 connected by a communication bus 24 . The communication bus 24 allows two way communication between the zone panel 22 and the boiler controller 20 . In the embodiment shown, the communication bus 24 is a standard ethernet cable with standard connectors 26 ( FIG. 2 ), such as, but not limited to RJ45 splitters.
[0022] In the embodiment shown, up to four (4) zone panels 22 may be connected to the boiler controller 20 at one time using. Each zone panel 22 may have up to four (4) zones, thereby allowing up to sixteen (16) zones to be monitored by the boiler controller 20 . Each zone has a thermostat 29 to sense the heating demand for that zone.
[0023] Additionally, a configurable communicating thermostat 30 may be connected to the zone panel 22 . The communicating thermostat 30 is “instanced” with an individual zone address. The communicating thermostat 30 allows a user to program an appropriate temperature range for each zone, as well as program various factors/inputs, including, but not limited to time of day and occupancy of home. Both the respective zone panel 22 and the boiler controller 20 receive input from the communicating thermostat 30 . In addition to the communicating with the zone panels 22 , the boiler controller 20 can communicate and control additional inputs and outputs. In the embodiment shown, twenty-four (24) additional inputs and outputs can be used. Such inputs/outputs are used, for example, to communicate with various sensors and to properly control the flow of heated water to the required zones. While particular numbers of zones, panels, thermostats, inputs and outputs, etc. are shown and described with respect to the illustrative embodiments, the invention is not limited to the numbers shown or described.
[0024] The boiler controller 20 may be, but is not limited to, an integrated controller that includes a single PC board or a small number of PC boards. The controller 20 may be housed in a single enclosure or housing that can be easily accessed. Each zone panel 22 may be, but is not limited to, an integrated controller that includes a single PC board or small number of PC boards. Each zone panel 22 may be housed in a single enclosure or housing that can be easily accessed.
[0025] In some embodiments, an outdoor air sensor 31 may provide temperature information that the boiler controller 20 may use to determine the appropriate boiler target temperature setpoint to efficiently operate the boiler 21 . For example, some boilers 21 are designed to create an efficiency curve that relates supply water temperature 32 to outdoor air temperature 31 . The boiler controller 20 may use these curves (or may include information related to or approximating these curves) to determine the target operating temperature of the boiler 21 at a given outside air temperature.
[0026] The boiler controller 20 may also capture information from other sources, such as, but not limited to, a supply water 32 and/or return water sensor 33 , which in the illustrative embodiment, determines the temperature of water leaving the boiler 21 and in the system at or just before the boiler 21 . The boiler controller 20 may use this information to adjust the heat output of the boiler 21 . In addition, other sensors commonly used in the industry may be provided to allow the boiler controller 20 to properly operate the boiler 21 to allow the boiler 21 to provide heat in an efficient manner.
[0027] In the illustrative embodiment shown, a first radiator or heat dissipation unit or heat emitter 40 supplies heat into the first zone 12, and a second radiator or heat dissipation unit 42 supplies heat into the second zone 14. A first water pump 44 controls whether water is forced through the first radiator or heat dissipation unit 40 into the first zone 12, while a second water pump 46 controls whether water is forced through the second radiator or heat dissipation unit 42 into the second zone 14.
[0028] During operation of the illustrative zoned multi-source system shown in FIG. 1 , the boiler controller 20 may sense whether either zone 12 and/or zone 14, which includes a thermostat 29 , indicates a call for heat. If there is a call for heat, the boiler controller 20 will determine the total demand and will fire the boiler and adjust the modulation rate according to the demand, as will be more fully described below. The boiler controller 20 also activates a water pump 50 , and zone panel 22 selectively operates water pump 44 and/or water pump 46 corresponds to the calling zone(s) to allow the heat to be delivered to the active zone which is calling for the heat. As will be more fully described below the activation of the boiler 21 , the heating or modulation rate and the like may be adjusted based on the information that the boiler controller 20 receives from the outdoor air sensor 31 , supply sensor 32 , return sensor 33 or other appropriate sensors/sources.
[0029] In some zoned systems, a multi-speed pump may be provided to vary the amount of water that is forced through the system depending on the number of calling zones. For example, the pump 50 may have two speeds and use a lower speed when only one zone is calling for heat, and a higher speed when two or more zones are calling for heat.
[0030] Referring to FIG. 2 , an illustrative control system 11 is shown diagrammatically. The system includes a boiler controller 20 which controls at least one boiler 21 and separate zone controller/panels 22 connected by a communication bus 24 . The communication bus 24 allows two way communication between the zone panels 22 and the boiler controller 20 . In the embodiment shown, the communication bus 24 is one or more standard ethernet cables with standard connectors 26 , such as, but not limited to RJ45 connectors and/or splitters. In the embodiment shown, two (2) zone panels 22 are connected to the boiler controller 20 . One zone panel has four (4) conventional thermostats 29 . The other zone panel has three (3) conventional thermostats 29 and a configurable communicating thermostat 30 . As discussed above, the communicating thermostat 30 is “instanced” with an individual zone address. Both the zone panel 22 and boiler controller 20 read this address and the information programmed into the communicating thermostat. While two zone panels 22 and eight thermostats 29 , 30 are shown, other numbers of panels 22 and thermostats 29 , 30 may be used without departing from the scope of the invention. For example, four (4) zone panels 22 may be connected to the boiler controller 20 at one time using the communication bus or busses 24 .
[0031] The boiler controller 20 controls the boiler 21 , as will be more fully described below. The boiler controller 20 also controls blowers, fuel valves, pumps or other items associated with the proper operation of the boiler 21 . A display panel 60 , such as, but not limited to, an LCD display is provided to provide information to the operator. In the embodiment shown, the display panel 60 is provided on the boiler; however, the display panel 60 may be located away from the boiler 21 .
[0032] The boiler controller 20 may also control several water pumps, including pumps for individual zones as required. The pumps control the flow of heated water to the individual zones. The pumps may be of any suitable type for use in an HVAC system. As previously described with respect to FIG. 1 , the boiler controller 20 may also receive information from an outdoor temperature sensor, a humidity sensor, and/or any other type of sensor.
[0033] To help determine whether the heating source/boiler 21 is capable of providing sufficient heat to satisfy the expected heating load of the zone(s) that are currently calling for heat, reference may be made to information relating to an estimated heating load of each of the zones and information relating to an estimated heating capacity of the heating source. The estimated heating load of the zone(s) that are currently calling for heat (active zones) as well as the estimated heating capacity of the heating source may depend on the outdoor air temperature and/or the outdoor air humidity.
[0034] Individual zones are monitored by the boiler controller 20 . When an individual zone is active a heat loss, as described above, associated with that zone is “switched in” or recognized by the thermostat 29 and communicated through the respective zone panel 22 to the boiler controller 20 . When “switched in” or active, that zone's heat loss is added together with the heat loss associated with other active zones. The total heat loss summation associated with active zones is compared with the maximum and minimum allowable boiler capacity. Once calculated, this heat loss summation is used to set the boiler's 21 maximum modulation rate. As the boiler 21 is released to modulation the boiler controller senses the boiler water temperature and compares the sensed water temperature to the information that the boiler controller 20 receives from the active type dissipation unit or heat emitter, the outdoor air sensor 30 , supply sensor 32 , return sensor 33 or other appropriate sensors and sets a firing rate. This firing rate is now limited to the heat capacity required by the active zones.
[0035] The maximum heating or modulation rate and setpoint varies as different zones are “switched in” and the water target setpoint varies as different types of heat emitters are active. Therefore, the boiler controller 20 continually monitors and communicates with the zone panels 22 and adjusts the setpoint and maximum modulation rate based on the changing demands received from the thermostats 29 , 30 .
[0036] If a zone panel 22 loses communication with the boiler controller 20 the maximum heat loss associated with that zone panel 22 is used as the default when setting the maximum modulation for boiler firing. If all zone panels 22 lose communication with the boiler controller 20 the maximum heat loss associated with all zone panels 22 is used as the default when setting the maximum modulation for boiler firing. This insures that sufficient heat will be provided to the home in case of a fault. Therefore, a fault or failure in communication results in the boiler using the maximum allowable boiler capacity to set the modulation rate, which is the equivalent to a conventionally heated home.
[0037] In addition to supplying heat, the system and method can be used to supply domestic hot water demand to a hot water tank 62 ( FIG. 1 ). In this arrangement, the hot water demand is treated as another zone. Therefore, when priority for hot water is not demanded or selected, the heating requirement for the hot water zone is added together with the other active heating zones. The total heat loss summation associated with active zones, including the hot water zone, is used to set the boiler's 21 maximum modulation rate. As the boiler 21 is released to modulation the boiler controller senses the boiler water temperature and compares the sensed water temperature to the information that the boiler controller 20 receives from the outdoor air sensor 30 , supply sensor 32 , return sensor 33 or other appropriate sensors/sources and sets a firing rate. This firing rate is now limited to the heat capacity required by the active zones.
[0038] However, if hot water is a priority, the hot water zone indicates the same. This allows the hot water zone to remain active and the other heating zones to be turned off. Under such circumstances, the maximum modulation of the boiler is set to the domestic hot water maximum modulation. This allows the boiler to be sized to suit the domestic hot water demand. The domestic hot water demand may be wired to either the boiler's or zone panel's domestic hot water demand terminals.
[0039] The water setpoint may be based on various factors/inputs, including, but not limited to individual zone demand, time of day, occupancy of home and outside air temperature.
[0040] In operation, various methods can be used to impact heat delivery. The following is a listing of exemplary methods for impacting heat delivery when the zone panels and the boiler controller described above are used. The methods recited are not meant as an exhaustive listing, as other methods to impact heat delivery may be used. While the exemplary methods are described below as a series of acts or events, it will be appreciated that the present invention is not limited by the illustrated ordering of such acts or events. For example, some acts may occur in different order and/or concurrently with other acts or events apart from those illustrated and/or described herein, in accordance with the invention. In addition, not all illustrated steps may be required to implement a methodology in accordance with the present invention. In addition, the illustrative methods are not meant to be mutually exclusive. Many or all of the methods may be used together.
[0041] A first illustrative method of impacting heat delivery is to adjust the maximum heating/firing rate based on the heating requirements of the active zones. In this process, the zone panels are programmed to reflect the heat loss associated with each individual zone. The boiler controller monitors the individual zones and determines which zones are active and require heat. The boiler controller then sums the heat loss of all active zones to calculate the total heat loss measured. The boiler controller calculates the heat output of the boiler based on blower rpm or pump speed. The boiler controller sets the actual heating/firing rate based on the heat output of the heating device and the measured heat loss. Variables which influence the firing rate include, but are not limited to, the measured temperature, the target water temperature set point and the maximum firing rate of the system. As the boiler controller continually monitors the system the controller recalculates demand as the active zone changes.
[0042] A second illustrative method of impacting heat delivery is based on the particular zone or zones that are active (or calling for heat). In this process, the zone panels are programmed to reflect the radiation type associated with each individual zone. Setpoints are programmed/established for up to three radiation types. For example, in a sixteen (16) zone system, zones 1, 2 or 5-16 may have first setpoint, zone 3 may have a second setpoint and zone 4 may have a third setpoint. The boiler controller monitors the individual zones and determines which zones are active and require heat. The boiler controller sets the boiler water target temperature based on the active heat demand type. The boiler controller modulates the boiler to reach this target while remaining below maximum heating/firing rate.
[0043] A third illustrative method of impacting heat delivery is to adjust heat loss based on individual zone call duration. In this process, a maximum zone run time is established and programmed into the boiler controller or the zone panel. The demand time is field adjustable. If the demand time exceeds the maximum zone run time, the boiler controller releases the boiler to maximum fire. The system has an ability to adjust boiler capacity for the total heat capacity of the home, maximum central heat demand or total heat capacity for domestic hot water, maximum domestic hot water demand. When the duration of any zone within these categories has exceeded the maximum zone run time the boiler capacity is released to the maximum for that category. This allows the system to adapt to changing conditions, such as, but not limited to, changes which effect zone heat loss, such as open windows or doors.
[0044] Alternatively, a reduced firing rate maximum run time for maximum firing rate reduced below boiler capacity may be established. If the actual run time exceeds the reduced firing rate maximum run time, the firing rate is adjusted to the maximum firing rate to boiler capacity.
[0045] A fourth illustrative method of impacting heat delivery is to adjust heat based on home status, such as, but not limited to, time of day and occupancy. In this process, the boiler controller communicates with and receives input from a communicating/programmable thermostat. The boiler controller adjusts the water temperature setpoint based on time of day and occupancy feedback from the thermostat.
[0046] A fifth illustrative method of impacting heat delivery is to adjust heat based on the outdoor temperature. In this process, the outdoor temperature is monitored and communicated to the boiler controller and/or the zone panels. Based on the outdoor temperature, each zone's setpoint temperature may be adjusted.
[0047] A sixth illustrative method of impacting heat delivery provides frost protection. In this process, the zone activity of each zone is monitored by the boiler controller or a zone panel. The outdoor air temperature is also monitored by the boiler controller or a zone panel. If it is determined that a particular zone has not operated in a set time period, i.e. one hour, and the outdoor temperature is below a set temperature, i.e. zero degrees Fahrenheit, the zone is activated, causing an individual zone pump and a primary pump to start, allowing warm water to move into the zone, thereby providing frost protection by preventing the water pipes from freezing. This will move warm water into a zone that may have a failed or poorly located thermostat. In this process, a zone is activated even when the thermostat is not requesting heat to protect from freezing.
[0048] A seventh illustrative method of impacting heat delivery provides diagnostic information to the user or service technician. Information regarding individual zones and system performance, such as, but not limited to, zone cycles counts, zone status, zone heat loss, zone alarms and other relevant information can be stored in the boiler controller or the zone panels. The information can be accessed using diagnostic equipment or through the display panel on the boiler. The information may be used to diagnose problems and to adjust various settings, including, but not limited to, thermostat settings, zone groupings or heat loss settings, to maximize the efficiency of the heating system and/or the users comfort.
[0049] The method and system described herein has many benefits. One such benefit is minimized cycling of the boilers. As the zone panels are continually communicating with the boiler controller, the boiler or boilers are started and stay running in response to the changing demand. This avoids wear and tear and standby losses.
[0050] Another benefit is that the firing rate is kept low or minimized. Allowing for a low firing rate enables the heating system to operate at a high efficiency operation. In addition, due to the minimized cycling and low firing rate, a steady, even heat is delivered, thereby increasing home comfort while maximizing efficiency. For example, when a home has a 150 kbtu boiler installed, using known or conventional technology and systems, the boiler is normally released with a boiler size of 150 k BTU. A conventional control would drive the boiler to high fire (150 k BTU) in response to measure supply temperature and the rate of rise of supply temperature and begin to reduce the firing rate only after supply temperature begins to rise. In contrast, when the system and method of the current invention is used and a 40 k BTU zone is calling for heat the boiler is sized to be 40 k BTU. The boiler then modulates between minimum modulation and 40 k BTU to satisfy the demand. The boiler is not driven to fire at 150 k BTU.
[0051] The use of the zone panels and boiler controller which allow for standard ethernet cable allows for easy installation for new and existing systems. This eliminates line and low voltage wiring between zone controls and the boiler control that is required in known systems.
[0052] Referring to FIG. 3 , the active boiler maximum modulation 70 is the maximum boiler modulation rate required to satisfy the active heat demand. This value is the combination of maximum heat loss from low temperature heating zones 71 , high temperature heating zones 72 and domestic hot water heating zone 73 . Domestic hot water heat zones 73 are added to the central heating zones or replace the central heating zone heat loss based on the priority selection 74 and priority timer 75 value. The low temperature heating zones heat loss and high temperature heating zones heat loss are subsets of the central heating maximum heat loss. Both the central heating and domestic hot water heat loss are compared with the boiler maximum 76 and boiler minimum 77 modulations. Upon loss of communication 78 the boiler control sets heat loss equal to the boiler maximum modulation 76 . Active zone demand time is monitored. If any active zone demand time exceeds the zone release time 79 the active boiler maximum modulation is set to the boiler maximum modulation. The boiler controller senses the boiler water temperature and compares the sensed water temperature to the target temperature setpoint further adjust firing rates for each boiler within the calculated maximum modulation rate. Target temperature setpoint is based on the type of dissipation units or heating elements. Separate setpoints are established for low temperature, high temperature and domestic hot water heating zones. These target temperature setpoints are further adjusted based on home status, including time of day or occupancy, outdoor air temperature and other settings. Individual zone status is used to develop a field resettable individual zone cycle count. The cycle count is used to alert an installing contractor to mechanical or electrical issues with the heating system.
[0053] In applications in which multiple boilers are used to provide heat, the boiler controller 20 performs the same functions as above to determine total required boiler heat capability required. However, instead of individual zone demands, the control may use other methods to obtain heat demand, such as, but not limited to, system pump speed, system differential temperature, system differential pressure. The boiler controller 20 fires required boilers to match the heat loss. The boiler controller senses the boiler water temperature and compares the sensed water temperature to the setpoint further adjust firing rates for each boiler within the calculated maximum modulation rate.
[0054] The system and method disclosed herein is described with reference to an exemplary boiler heating system. However, the system and method is applicable and can be used with other types of heating systems, including, but not limited to heat pumps or furnaces. The system and method is applicable and can be used with cooling systems and other types of air conditioning systems. In addition, the system and method can be with heating or cooling systems which have one or more heating or cooling sources.
[0055] In general, the method described herein is for controlling a multiple zoned heating/cooling system. The method includes: communicating to a controller individual active zones of the multiple zoned heating/cooling system which require heating/cooling; establishing the heating/cooling demand size for the active zones; summing the total heating/cooling demand size required by the active zones; establishing a maximum firing/cooling rate for a heating/cooling device based on the total heating/cooling demand required by the active zones; and setting a temperature setpoint for a heating/cooling device based on outside air sensor 30 , supply sensor 32 , return sensor 33 or other appropriate sensors. This firing rate/cooling rate is now limited to the heat capacity required by the active zones.
[0056] While the invention has been described 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 spirit and scope of the invention as defined in the accompanying claims. In particular, it will be clear to those skilled in the art that the present invention may be embodied in other specific forms, structures, arrangements, proportions, sizes, and with other elements, materials, and components, without departing from the spirit or essential characteristics thereof. One skilled in the art will appreciate that the invention may be used with many modifications of structure, arrangement, proportions, sizes, materials, and components and otherwise, used in the practice of the invention, which are particularly adapted to specific environments and operative requirements without departing from the principles of the present invention. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being defined by the appended claims, and not limited to the foregoing description or embodiments.
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A multiple heating/cooling zone control system is disclosed. A heating/cooling system control device continuously monitors heating/cooling zone demand and matches the heating/cooling device output capacity to the total space or heat input required. Within the calculated heating/cooling device output capacity the heating/cooling device is modulated based on zone temperature setpoint to further adjust heating/cooling device output. As heat/cooling loss is increased heating/cooling device capacity and modulation are increased. Should heat/cooling loss decrease heating/cooling device capacity and modulation are decreased. Since heat/cooling output is adjusted based on the heat loss(gain) the heating/cooling device can be immediately adjusted to the proper or matching heating/cooling rate even before water/air temperature based adjustments can be made. Hence, the overall effect of the control device is a reduction in cycles of the heating/cooling device and the life of the heating/cooling device is extended and subsequent energy is saved.
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BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates to hydraulic power supplies, and more particularly to air operated volumetric hydraulic power units ideally suited for powering high production multiple head welding machines and like equipment.
Machines using fluid motors (e.g., piston and cylinder assemblies) to drive working pistons for clamping tools, actuating tools or welding guns, etc. are generally either pneumatically or hydraulically powered. If high speed is required air is often preferred because it is cleaner and will give faster action than oil at the same supply pressure; however, saftey limits on usable pressures result in cylinder sizes which are too large for many applications. Oil can be used at higher pressures, thereby reducing cylinder sizes, but to get fast action relatively large displacement pumps are required. Hydraulic power units therefore tend to be large and costly, and because they have continuously operating pumps (even during the dwell or rest portion of the load cycle, because they must be able to quickly meet any sudden demand) they consume substantial amounts of power (variable displacement pumps may consume only moderate power, but are even more costly) are a source of continuous noise, and generate considerable heat because all excess is dumped back to the reservoir after being raised to working pressure.
It is therefore a primary object of this invention to provide an improved hydraulic power supply which operates on demand only, i.e., it supplies oil under pressure only when required by the load, thereby virtually eliminating the consumption of power (and attendant operating cost), noise and heat build-up when the load is in the dwell or rest part of its cycle (often a substantial proportion of the total cycle time). A related object resides in the provision of unique reset means for insuring full completion of each cycle of the power unit prior to initiation of a new cycle.
Further objects of the present invention concern the provision of a demand type hydraulic power unit which can be easily sized for any volumetric demand, which is relatively compact and economical, which can provide desired high speeds without requiring bulky and costly accumulators, and which can be retrofit to existing machines.
Another object of this invention resides in the provision of a demand type hydraulic power unit which optionally can provide an intensified output for those applications where a two-stage advance stroke is desired, i.e., one in which the hydraulic piston initially advances toward the workpiece at a high rate of speed but with relatively little force, and upon engagement with the workpiece provides very high force but with limited displacement.
A further object of this invention resides in the provision of an auxiliary hydraulic power unit coupled with the primary power unit which discharges intensified oil during the return pressurized function of the primary power unit to lock up retract oil in the return machine manifold to keep the rod ends of the working pistons from drifting downward when the fluid motor is shut down for a period of time (and pistons are mounted with rod ends down) and also intensify return oil to retract end of working piston (when stuck due to bent rods or the like).
A further advantage of the present invention is that in one embodiment fluid is returned to a hydraulic slave cylinder under pressure (and not through a reservoir) for a faster refill caused by the back pressure of the unit and thereby faster cycling of the unit.
In some instances, fewer hydraulic working pistons may be used and less air is necessary to drive the power unit. In such cases, a significant cost advantage occurs if the working volume of the master cylinders are diminished. It is a further advantage of the present invention to provide a simple and efficient means of reducing the working volume of the master cylinders as desired to attain a cost savings using less pressurized air when fewer working pistons than the maximum number are utilized.
Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic circuit diagram of a first embodiment hydraulic power unit of the present invention. Oil conduits are shown as solid lines and air conduits are shown as broken lines;
FIG. 2 is an elevated perspective view of an alternative embodiment of a hydraulic power unit of the present invention;
FIG. 3 is a schematic circuit diagram of the unit illustrated by FIG. 2;
FIG. 4 is a schematic circuit diagram of the working cylinder conduit system of the circuit of FIG. 3;
FIG. 5 is a vertical sectional view taken along line 5--5 of FIG. 2;
FIG. 6 is a horizontal sectional view of a spacer assembly taken along the line 6--6 of FIG. 5; and
FIG. 7 is a side view similar to FIG. 5 of an alternate embodiment of the master cylinders of the present invention with portions of the unit in elevation.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, generally, the embodiment of the present invention disclosed therein comprises a hydraulic power unit 10 and a hydraulically operated machine 12, incorporating a plurality of working cylinders 14 each having a working piston 16 therein, a phantom line separating unit 10 from machine 12 in the drawing. Although machine 12 may be of any type requiring power in the form of a volume of oil under pressure, the present invention is particularly suited for use in power multi-gun welding machines of the type used in the mass production of automobiles, appliances and the like. Each such machine may have dozens of separate guns, each requiring a separate working cylinder. If desired, suitable unions or couplings may be provided between the power unit and the machine.
The power unit of the present invention comprises a pneumatic extensible fluid motor or power cylinder 18 having a piston 20 therein; a solenoid operated air supply valve 22 connected to motor or cylinder 18 by fluid conduits 23 and 25 and normally spring biased to a first position (as shown) to place the head end of piston 20 in fluid communication with a pressurized source of air (e.g., plant air) and the rod end thereof in fluid communication with the atmosphere, and actuatable by the solenoid to a second position to place the head end of piston 20 in fluid communication with the atmosphere and the rod end thereof in fluid communication with the pressurized source of air; and a hydraulic extensible fluid motor or slave cylinder 21 having a piston 24 therein, piston 24 being operatively connected to and powered by piston 20, slave cylinder 21 being connected via fluid conduits 24' and 26 to a solenoid operated oil supply valve 28, via a conduit 30 to a supply or advance oil conduit 31 communicating with the head end of each of the working cylinders, and via a conduit 32 to a return or retract oil conduit 33 communicating with the rod end of each of the working cylinders, whereby movement of piston 24 downwardly (as shown) will cause oil to be pumped out of slave cylinder 21 through conduits 24', 30 and 31 to advance each working piston, and movement upwardly (as shown) will cause oil to flow through conduits 26, 32 and 33 to retract each working piston. The rod end of slave cylinder 21 should have an oil volume substantially greater than the total volume of all the head ends of all the working cylinders (plus the volume of the relevant conduits and actuators) to make sure that there is always sufficient oil to quickly advance the working pistons when desired and to accommodate all leaks (which are unavoidable).
Solenoid operated oil supply valve 28 is normally spring biased to a first position (as shown) to place the rod end of piston 24 in fluid communication with the oil in reservoir 34 and to block fluid communication between the head end thereof and reservoir 34, and is actuatable by the solenoid to a second position to place the head end of piston 24 in fluid communication with the oil in reservoir 34 and to block fluid communication between the rod end thereof and reservoir 34.
Also provided is a solenoid operated oil return valve 36 normally spring biased to a first position (as shown) to place the head end of each working piston in fluid communication with oil reservoir 34 via a fluid conduit 38 and to block fluid communication between the rod ends thereof and said reservoir via a fluid conduit 40, and actuatable by the solenoid to a second position to place the rod end of each working piston in fluid communication with reservoir 34 via conduit 40 and to block fluid communication between the head end thereof and said reservoir.
One of the unique aspects of the present invention resides in the provision of reset means to assure that piston 24 in slave cylinder 21 fully retracts each cycle of the apparatus. The reset means of the present invention comprises a two-position reset valve 42 connected to slave cylinder 21 by fluid conduits 43 and 44, and operable in its first position (as shown) to place the head end of piston 24 in fluid communication with the oil in reservoir 34, preferably below the oil level therein to eliminate any chance of drawing air in on reversal of piston movement, and in its second position to block fluid communication between the head end of piston 24 and the oil in reservoir 34. Reset valve 42 is actuated to one or the other of its two positions by a reset valve actuator comprising a cylinder 46 having a piston 48 therein connected to the reset valve. The head end of piston 48 is in fluid communication with conduit 30 via fluid conduits 50 and 52, and the rod end of piston 48 is in fluid communication with the head end of piston 24 via conduit 44.
In applications where two-stage power is required, i.e., a high speed low force advance stroke followed upon workpiece engagement by a low speed high force working stroke, intensifying means may be provided. The intensifying means of the present invention comprises a relatively large air cylinder 54 having an air piston 56 therein, and a relatively small oil cylinder 58 having a piston 60 therein powered by air cylinder piston 56. Oil cylinder 58 is in fluid communication with conduit 30 via conduits 50 and 52. The intensifying means is controlled by a two-position sensing valve 62 in fluid communication with the rod end of piston 20 by fluid conduits 64 and 66 and with the head end of air piston 56 by fluid conduits 68 and 70, and operable in its first position (as shown) to block communicaiton between cylinder 18 and cylinder 54, and in its second position to place the rod end of piston 20 in fluid communication with the head end of piston 56, to generate relatively high oil pressures in cylinder 58, which is communicated to oil supply conduit 31 and the head ends of the working pistons via conduits 50, 52 and 30. Conduit 70 also functions as a bypass conduit connecting the head of piston 56 with the rod end of piston 20, and has a check valve 78 disposed therein for permitting venting of air cylinder 54 on the return stroke of piston 56. The rod end of piston 56 is permanently vented at 80.
Sensing valve 62 is actuated to one or the other of its two positions by a sensing valve actuator comprising a cylinder 72 having a piston 74 therein connected to the sensing valve, the head end of piston 74 being connected to conduit 32 via a fluid conduit 76 and the rod end thereof being connected to the rod end of piston 20 via conduit 66. If two-stage operation is not required, or extra high forces are not necessary, the intensifier means of the present invention may be omitted.
A check valve 82 is provided in conduit 30 for preventing flow therefrom, or from cylinders 46 or 58 into slave cylinder 21, and a check valve 84 is provided in conduit 32 for preventing flow therefrom or from cylinder 72 into slave cylinder 21.
The power unit of the present invention has an operating cycle which comprises the steps of advance, intensify, retract and reset. As shown in FIG. 1, the system is in its fully retracted and reset condition, with no power supplied to the solenoid valves. In this condition the three solenoid valves are in their normal spring biased position illustrated, the power piston is fully advanced and the slave piston fully retracted, all of the working pistons are fully retracted, and the intensifier piston is fully retracted. For purposes of description, it will be assumed that each of the working pistons is provided with a working element (clamp, welding gun, etc.) which engages a workpiece, and that it is desired to have the working element advance toward the workpiece at a high rate of speed but with relatively little force, and upon engagement with the workpiece provide a very high force but with limited displacement.
In this retracted condition, the head ends of working pistons 16, the head end of reset actuator cylinder 46 and intensifying cylinder 58 are in fluid communication with reservoir 34 via oil return solenoid valve 36, the rod end of slave piston 24 is in fluid communication with reservoir 34 via oil supply solenoid valve 28, the rod end of power piston 20 is in communication with the atmosphere via air supply solenoid valve 22, and the head end of intensifier air piston 56 is in communication with atmosphere by virtue of its connection to cylinder 18 at the rod end of power piston 20, via check valve 78. The system has reached this position and is maintained in this position by the pressure of plant air on the head end of power piston 20 via air supply solenoid valve 22.
When it is desired to actuate the hydraulic machine 12, electric power is supplied to solenoid valves 22, 28 and 36 to actuate them from the first position shown to their second position. This initiates the advance portion of the machine cycle. Air under plant pressure is supplied via air supply valve 22 to the rod end of power piston 20 to cause the latter to move downwardly (as shown). Air is exhausted from the head end of power piston 20 to the atmosphere via air supply valve 22. Downward movement of power piston 20 causes a corresponding movement of slave piston 24, which in turn causes oil to be forced from slave cylinder 21 via conduits 24', 30 and 31 to the head ends of working pistons 16 to cause the working elements thereof to advance towards the workpieces (not shown). The rod ends of working pistons 16 are in fluid communication with the atmosphere via oil return valve 36. The head end of slave piston 24, as well as the rod end of reset valve actuator piston 48, draw oil from the reservoir via oil supply valve 28. This permits slave piston 24 to move downwardly and actuator piston 48 to move to the right (as shown) under the influence of pressure generated in the slave cylinder (via lines 50 and 52) to actuate reset valve 42 to a position in which fluid communication between the head end of slave piston 24 and the reservoir is blocked.
During the advance stroke (which may take less than one second), the back pressure in conduits 33 and 40 is sufficiently high due to flow losses throughout the system that the residual pressure on the head end of sensing valve actuator piston 74 is sufficient to overcome air supply pressure applied to the rod end thereof (the respective areas of the piston can be designed to assure that this is true). When the working elements engage the workpiece and advance motion of the working pistons 16 ceases, the back pressure in conduits 33 and 40 drops and the air pressure in sensing valve actuator cylinder 72 overcomes the hydraulic back pressure and piston 74 moves to the left, thereby actuating sensing valve 62 to place plant air in fluid communication with the head end of intensifying air piston 56. The pressure on this relatively large piston creates relatively high oil pressures in intensifying cylinder 58, which pressures are communicated to the head ends of the working pistons via conduits 50, 52, 30 and 31, whereby high forces are generated between the working elements and workpieces (not shown). This is the intensifying portion of the machine cycle and it occurs after the workpieces have been engaged by the working elements. The rod end of intensifying air piston 56 is vented at 80. The apparatus remains in the intensifying condition until all three solenoid valves are deenergized.
Deenergization of the three solenoid valves initiates the retract portion of the machine cycle, which causes the system to return to the condition illustrated in the drawing. During the retract portion of the cycle, air under pressure is supplied by air supply valve 22 to the head end of power piston 20 to cause it and slave piston 24 to move upwardly (as shown) to generate oil pressure at the head end of slave piston 24 which is in fluid communication with the rod ends of the working pistons, thereby causing them to retract. That same hydraulic pressure causes sensing valve actuator piston 74 to move to the right to reset sensing valve 62.
When the working pistons have fully retracted, the back pressure in conduits 31, 30, 52 and 50 decreases to the point where the pressure communicated to the rod end of reset valve actuating piston 48 moves the latter to the left to place the head end of slave piston 24 in fluid communication with the reservoir. This is the reset portion of the power unit cycle and is absolutely necessary to insure that the slave cylinder fully returns to the position illustrated, so that it can perform a full volume cycle thereafter upon demand. In the absence of reset valve 42 and its actuator, slave piston 24 would fluid lock prior to returning to its fully retracted position by virtue of the fact that less oil is needed to retract the working pistons than is needed to advance them because of the reduced volume in the rod ends of the cylinders as compared to the head ends. Also, leaks are unavoidable and are greater on the advance stroke because of higher oil pressures.
During the retract portion of the cycle the head ends of the working pistons force the oil in the head ends of the working cylinders into the reservoir via oil return valve 36, the rod end of slave piston 24 draws oil into the rod end of cylinder 21 from the reservoir via oil supply valve 28, and the rod end of power piston 20 exhausts to atmosphere via air supply valve 22. The head end of intensifier air piston 56 is in communication with atmosphere via check valve 78 so that the back pressure in conduits 31, 30, 52 and 50 will cause the intensifier piston to return to the position illustrated.
It is believed that a hydraulic power unit incorporating applicant's invention, using a power cylinder having an 8" bore and a 4" stroke and a slave cylinder having a 7" bore, in combination with an intensifier wherein the air piston has a 6" bore and a 3" stroke and the oil cylinder has a 21/4" bore, will replace an existing hydraulic power unit requiring a 40 gpm pump, a 30 H.P. electric motor, a 120 gallon reservoir, an air/oil accumulator and a heat exchanger, the latter being required to cool pressurized oil which is not used and therefore must be dumped back into the reservoir. Applicant's power unit may weigh only 250 pounds, compared to 5000 pounds for the state-of-the-art unit, and requires only a 4 gallon reservoir. Standard criteria are used in choosing the strokes and bores of the various cylinders, depending on the volumes, strokes and forces desired.
An alternative embodiment of the present invention is illustrated by FIGS. 2, 3 and 4, comprising a hydraulic power unit 100 and a hydraulically operated machine 12, such as that shown in FIG. 1, incorporating a plurality of working cylinders 14 each having a working piston 16 therein, but eliminating oil lines 38 and 40 and the oil return valve 36 (FIG. 4). The power unit 100 comprises four master extensible fluid motors 102, as represented by pneumatic cylinders 102, interconnected at an axially intermediate point by a plate 104. Each cylinder 102 comprises an upper cylindrical retract air power transmitting member or piston 106 and a lower cylindrical advance air power transmitting member or piston 108 each fixedly secured to the plate 104 in a manner that the plate 104 closes off one end of each of the pistons 106 and 108. The four upper pistons 106 are each slidably secured within upper retract air housings 110 which in turn are fixedly connected onto upper plate 112. The four lower pistons 108 are each slidably secured within lower advance air housings 114 which are fixedly connected onto a lower plate 116.
A slave extensible fluid motor 118, as represented by hydraulic slave cylinder 118, having a cylindrical upper advance oil power transmitting member or piston 120 and a lower cylindrical retract oil power transmitting member or piston 122 fixedly secured to the intermediate plate 104 concentrically on opposite sides of the plate, is disposed in a laterally intermediate location of the master extensible fluid motors or pneumatic cylinders 102. Upper piston 120 and lower piston 122 are slidably disposed in cylindrical housings 124 and 126, respectively, in a manner similar to the construction of the cylinders 102. Upper housing 124 is fixedly secured to upper plate 112 at the center of the plate 112 and lower housing 126 is similarly fixedly secured to lower plate 116.
The intermediate plate 104 has guide means comprising eight apertures through the plate 104 through which rods are disposed, four rods 128 located toward the interior of the plate 104 adjacent the hydraulic slave cylinder 118, and four rods 130 disposed at the four corners of the plate 104 exteriorly of the pneumatic master cylinders 102. All eight rods 128 and 130 are utilized to space apart and fixedly tie together upper plate 112 and lower plate 116. The four corner rods 130 also function to guide the intermediate plate 104 in its upward and downward movements during the operation of the hydraulic power unit.
Thus the intermediate plate 104 moves upwardly and downwardly primarily in response to the movement of the four master cylinders 102, guided by the rods 130. The plate 104 then transmits movement to the hydraulic slave cylinder 118, whereby the slave cylinder 118 moves in unison with the master air cylinders 102 disposed around it.
Referring to FIG. 3, the power unit 100 of the present invention further comprises a solenoid operated air supply valve 132, including silencers 133, connected to the pneumatic master cylinders 102 by fluid conduits 134 and 136 and normally spring biased to a first position (as shown) to place the upper pistons 106 of the master cylinders 102 in fluid communication with the atmosphere and the lower pistons 108 of the cylinders 102 in fluid communication with a pressurized source of air (e.g., plant air), and actuatable by the solenoid 135 of the valve 132 to a second position to place the upper pistons 106 of the cylinders 102 in fluid communication with the pressurized source of air and the lower pistons 108 in fluid communication with the atmosphere; and hydraulic slave cylinder 118 being connected via fluid conduits 138 and 139 (via check valve 141) to both a return or retract oil conduit system 140 (communicating with the rod end of each of the working cylinders 14) and to a conduit 142 communicating with a pneumatically-operated hydraulic four-way valve 144, and being connected via fluid conduit 146 to both conduit 148 (via check valve 147), communicating with the hydraulic four-way valve 144 via conduit 150 and to an oil reservoir 152 (vented to atmosphere) via conduit 154, and via fluid conduits 155 and 156 to fluid conduit 158 (via check valve 157), which communciates with both the supply or advance oil conduit system 160 (communicating with the head end of each of the working cylinders 14) and the hydraulic four-way valve 144 as the alternate port to that provided by conduit 142. Disconnects 161 and 162 are included to permit interchangeability between the power unit 100 and various working units as desired.
The alternative embodiment described herein utilizes only one hydraulic four-way valve 144 to control the oil flow throughout the unit 100 instead of the two valves required by the unit of FIG. 1. The oil supply valve 144 is also pneumatically controlled via fluid conduit 163 communicating with conduit 136 to associate the operation of the hydraulic supply valve 144 with the operation of the solenoid operated air supply valve 132. With the air supply valve 132 set (as shown) in the advance position, the hydraulic supply valve 144 is actuated to an advance position (as shown) against the spring bias of its normal (retract) position to communicate fluid conduit 158 with fluid conduit 164 and communicate fluid conduit 142 with fluid conduit 150.
The power unit 100 has unique features of providing intensified return oil to the working cylinders (which becomes important when the pistons 16 are stuck due to bent rods, etc.) and providing a lock-up for retract oil in the return oil conduit system 140 (which is desirable to keep the piston rods from drifting downwardly when the machine element is shut down for a period of time and the cylinders 14 are mounted with the rod ends down). The power unit 100 incorporates two relatively small, short-stroke, single-acting hydraulic cylinders 166 and 168 having the rod end 167, 169 of each respective piston 170 and 172 vented to atmosphere. The cylinders 166 and 168 are fixedly secured to the lower plate 116 with the rod ends 167, 169 of the pistons 170 and 172 directed upwardly toward the intermediate plate 104 so as to be contacted by the plate 104 at a point in the downward travel (retract) of the plate 104, whereby the plate 104 forces the pistons 170 and 172 downwardly through the cylinders 166 and 168 forcing oil into fluid conduit 164 which operably communicates with both of the cylinders 166 and 168. The plate 104 engages the rod ends 167, 169 before the end of the stroke of the cylinders 102 and 118. Thereby, if oil is lost in the return oil conduit system 140, reserve oil exists during the stroke of the cylinders 166 and 168 to refill that return system 140.
Cylinders 166 and 168 are charged with oil from the hydraulic four-way valve 144 during the advanced slave pressurized function of the operation through conduit 164. This same oil is discharged from the cylinders 166 and 168 through conduit 164 in the return slave pressurized function of the cycle greatly intensified through the valve 144 into the return or retract system 140 and thereby into the gun retract manifold. A check valve 141 keeps the intensified oil directed to the return system 140 and nothing further is required to sequence the two cylinders 166 and 168 due to the mechanical design of the unit 100.
The reset sensor 42, 46 of the emdodiment of FIG. 1 has also been eliminated and the cycle time has been shortened with this embodiment by utilizing a large flow control check valve 176 with an oil conduit 178 communicating with the fluid conduit 150 at the discharge side of the supply valve 144 when the valve is in the Retract (normal) position (not shown) and also communicating with the fluid conduit 154 communicating wih the oil reservoir 152. Since the welding guns will be retracted (whether a few or many in number) in a matter of 0.3 to 0.4 of a second, a by-pass flow control 180 can be left partly open (a locked setting), running off some of the pressurized oil from the return slave portion (lower piston 122) during the retracting of the welding guns and complete the Reset part of the cycle by running off the balance of the excess oil (under pressure) through conduits 148 and 146 directly into the advance slave portion (upper piston 120) of the cylinder 118 and/or to the reservoir 152 via conduit 154.
The advance slave portion (upper piston 120) of the cylinder 118 should have an oil volume substantially greater than the total volume of all of the head ends of all of the working cylinders 14 (plus the volume of the relevant conduits and actuators) to make sure that sufficient oil always exists to quickly advance the working pistons when desired and to accommodate all leaks (which are unavoidable). With the unit 100 of FIGS. 2 and 3, the fluid from either side of the gun working cylinders is always discharged through the hydraulic four-way valve 144 directly back into the slave cylinder 118 under pressure along with communicating with conduit 154 (and thereby reservoir 152) to balance out any plus or minus in the actual volume of oil which may have been caused by leaks. The balancing process is also performed faster since the slave cylinder 118 will be refilled by oil under all the back pressure of the guns instead of being refilled solely by drawing oil from the reservoir (at atmospheric pressure).
Intensifying means has also been provided where two-stage power is required, i.e. a high speed, low force advance stroke followed upon workpiece engagement by a low speed, high force working stroke. In the embodiment of FIGS. 2 and 3, an oil over oil intensifier 182 is used. The intensifier 182 has three working chambers 184, 186 and 188 in a dual cylinder 190 and 192 arrangement, the chambers formed by head and rod ends of a double-acting piston 194 having piston heads 196 and 198, one disposed in each cylinder 190 and 192, respectively. The head end of piston head 198 in cylinder 192 forms a working chamber 188 which communicates via conduit 200 with conduit 158 which communicates with both the advance oil conduit system 160 (and the head end of each of the working cylinders) and the hydraulic four-way valve 144 as the alternate port to that provided by conduit 142. The rod end of piston head 196 in cylinder 190 forms a working chamber 186 which communicates via conduit 202 with conduit 139 which, in turn, communicates with both the retract oil conduit system 140 (communicating with the rod end of each of the working cylinders) and to conduit 142 communicating with the other port of the same valve 144 with which conduit 158, and thereby working chamber 188, communicates. The head end of piston head 196 in cylinder 190 forms working chamber 184. Conduit 204 communicates with working chamber 184 and both a sequence valve 206 communicating with the acdvance oil portion 120 of the hydraulic slave cylinder 118 via conduits 208, 155, and 146 and a conduit 203 bypassing the sequence valve 206, including a check valve 205 within the bypass. The sequence valve 206 has a pilot 210 with a fixed orifice selected to sequence the valve 206 in a selected period of time. In the preferred embodiment, all guns whether a few or a large number will advance in approximately 0.3 to 0.4 of a second. Thus, the pilot 210 can be fixed to sequence in 0.5 seconds and always sequence after the guns have advanced. It should be noted also that a similar sequence valve could be utilized as a substitute for flow control 180 for the reset control as described above although the flow control 180 is preferred since it is believed to be simpler mechanism for reset control.
The advance intensifier 182 as described is powered by the use of some of the oil from the advance oil piston 120 of the hydraulic slave cylinder 118 to greatly reduce the size of the intensifier (oil over oil versus air over oil). The intensifier 182 also does not need to have a sensor reading the falling off of back pressure to sequence the intensifier 182 but instead the sequencing can be performed more predictably with the sequencing valve 206.
When it is desired to activate the hydraulic machine 12, electric power is supplied to activate the solenoid 135 of the air supply valve 132 to the position shown in FIG. 3. This initiates the advance portion of the machine cycle. Air under plant pressure is supplied via valve 132 and conduit 136 to both the four lower advance air pistons 108 of the master cylinders 102 and via conduit 163 to activate the hydraulic four-way valve 144 to the position shown. Air is exhausted from the upper pistons 106 of the master cylinders 102 to the atmosphere via conduit 134 and valve 132. Upward movement of the master cylinders 102 causes plate 104 to move slave cylinder 118, which in turn causes oil to be forced out of the advance oil pistion 120 of the slave cylinder 118 into conduits 146, 155 and 156 into the supply or advance oil conduit system 160 to the heads of the working pistons 14 of the guns to cause the working elements thereof to advance toward the workpieces (not shown). Check valve 147 separates the oil under pressure in conduit 146 from entering conduit 148 and passing into the retract oil conduit system 140. The rod ends of the working pistons 14 of the guns are in fluid communication with the retract or return oil conduit system 140 and conduit 138 and oil forced out by the advance stroke flows into conduit 139 to ultimately enter the return oil piston 122 of the slave cylinder 118 via conduit 142, valve 144, and conduits 150, 178 and, via valve 176 and conduit 138 with the option of also returning to the oil reservoir 152 via conduit 154.
In the embodiment as presently represented, after 0.5 seconds into the advance stroke, the guns should be sufficiently advanced for intensification. The pilot 210 of the sequence valve 206 is being bled oil from conduit 155 via conduit 208 until the spring load of the valve is overcome to pass oil into working chamber 184 via conduit 204. The oil forces piston head 196 upwardly to force oil out of working chamber 186 through conduit 202 to conduit 139 into the same options as the oil coming out of the retract oil conduit system 160, i.e. return to the slave cylinder 118 at the return oil piston 122 or into the oil reservoir 152. Piston head 198 is also forced upwardly to force oil out of working chamber 188 into the advance oil conduit system 160, via conduits 200 and 158, to intensify the advanced working elements, generating high forces between the working elements and the workpieces. The apparatus remains in this intensifying condition until the solenoid operated air supply valve 132 is energized to the retract position.
Energization of valve 132 to the retract position initiates the retract portion of the machine cycle, which causes the system to move out of the condition illustrated in the drawing. During the retract portion of the cycle, air under pressure is supplied by air supply valve 132 to the four upper retract air pistons 106 of the master cylinders 102 via conduit 134. Conduit 136 is vented to the atmosphere by the valve 132 in this retract position exhausting both the four lower pistons 108 of the master cylinders 102 and conduit 163, which in turn cause the spring loaded hydraulic valve 144 to move to the retract position (not shown). The plate 104 is moved downwardly due to the air pressure in upper pistons 106 to generate oil pressure in the lower retract piston 122 of the slave cylinder 118, forcing oil into the retract oil conduit system 140 via conduits 138 and 139 to supply pressurized oil at the rod ends of the working pistons 16, causing them to retract. That same oil resets the advance intensifier 182, flowing into working chamber 186 from conduit 139 via conduit 202.
The retraction of the working pistons forces oil out of the advance oil conduit system 160 to assist in returning the position of the advance intensifier 182 back to normal (not shown) via conduits 158 and 200 into working chamber 188 and also return oil via conduit 158 and valve 144 to the advance piston 120 of the slave cylinder 118 via conduits 150, 148 and 146 or to the reservoir 152 via conduits 150 and 154. Then the Reset feature and the Retract intensifier will come into operation as described above to complete the cycle and then maintain the position of the working pistons until the air supply valve 132 is energized into the Advance position to begin a new cycle.
It should be noted that if a low viscosity mixed fluid, such as a 95-5 water-synthetic fluid is desired to be used instead of oil, it may be preferable to substitute three air pilot operated check valves for the four-way valve 144 to prevent bypass of the low viscosity oil through the valve 144. Two of the pilot operated check valves would directly replace the four-way valve 144 and the third would be attached to a bypass conduit to refill the retract intensifier cylinders 166 and 168.
As illustrated in FIG. 5, upper piston 106 of master extensible fluid motor or air cylinder 102 comprises a rod 220 that is disposed through an aperture 222 in plate 104 and welded to an annular ring 224 at an intermediate point on the rod 220. At the upper extreme of the rod 220 is welded a piston head 225. Piston head 224 is operably disposed in housing 110 to form the upper cylindrical retract air piston 106. Piston head 225 has a suitable sealing ring 226 associated therewith.
Below the plate 104 a second rod 228 is fixedly attached to the plate 104 and a second piston head 230 is welded to the opposite end of the sleeve 228. Piston head 230 is operably disposed in housing 114 to form lower cylindrical advance air piston 108. Piston head 230 also has a suitable sealing ring 232 associated therewith.
The annular ring 224 of the upper piston 106 is secured to the plate 104 via a spacer assembly 234 for adjusting the volume of the piston 106. If fewer guns are used in some instances, a large cost savings in pressurized air can be made if the volume of the master air cylinders 102 can be easily decreased. The spacer assembly 234 of FIGS. 5 and 6 accomplishes this advantage in a simple, efficient manner. Spacers 236 and 238, having a configuration as shown in FIG. 6, are stacked on top of the annular ring 224. The spacers 236, 238 each have four slots 240, 242, 244 and 246. The middle slot 242 engages rod 220. Bolts 248 and 250 are engaged by slots 240 and 244 respectively before the bolts 248, 250 pass through the annular ring 224 and threadably engage the plate 104 at threaded holes 252 and 254. Washers 256 and 258 are used to provide a wider and more even interface between the bolts 248, 250 and the top spacer 236. Threaded rod 260 engages the posterior slot 246 and threadably engages the plate 104 at bore 262 after passing through the annular ring 224. The rod 260 is rotated by movement of crossmember 264 welded thereto. A washer 266 is also welded to the rod 260 to provide a lateral locking interface with the top spacer 236.
Threaded restraining rod 260 is utilized to restrain the movement of the spacers 236, 238 and secure them in position. Bolts 248 and 250 and rod 220 align the spacers 236, 238 in their operative position. Volume of the piston 106 is diminished by placement of one or both of the spacers 236, 238 below the annular ring. Restraining rod 260 is removed, one or both spacers 236, 238 are slidably removed, annular ring 224 is moved upwardly, one or more spacers 236, 238 are placed between the ring 224 and the plate 104, and the retraining rod 260 is replaced to resecure the assembly 234 together. In this manner, the volume of the piston 106 is diminished by the height of the spacer or spacer positioned below the ring 224 times the cross-sectional area of the bore of the piston 106.
FIG. 7 illustrates another construction of the master cylinders 102 of the unit 10. Air bags 280, 282 of the type manufactured by the Goodyear Tire and Rubber Company, Industrial Products Division, Akron, Ohio are used as a less expensive alternative to the pistons 106 and 108 of the extensible fluid motors 102 of the unit 10. Illustrated in FIG. 7 are Goodyear 2B Double Convolute-Bellows Type air bags comprising metal upper 284, 285 and lower 286, 287 power transmitting or retainer members, including blind taps 288 for bolts 290 attaching the air bags 280 and 282 to the plates 104, 112 and 116, an air hose fitting 292, a flex member 294, a girdle ring 296 around the intermediate point of the flex member 294, and taps 298, 300 threadably engageable with rod 302 at each end thereof respectively, the rod 302 passing through bore 304 in plate 104 whereby the air bags 280 and 282 are secured to the plate 104 in assembly with the rod 302. The volume of air needed to actuate the air bags 280 and thereby the unit 10 may be diminished if the full capacity of the air bags 280 is not needed (such as with a less than maximum number of working pistons in a desired usage situation) by filling the air bags partially with water or an antifreeze solution. The embodiment illustrated in FIG. 7 may also be utilized in association with the various intensifier cylinders in the manner described above as utilized with the pneumatic piston extensible fluid motors 106 and 108 as illustrated by FIGS. 2 through 6.
Thus, there is disclosed in the above description and in the drawings an improved hydraulic power unit which fully and effectively accomplishes the objectives thereof.
The dimensions and sequence times set forth in the above specification are merely representative and are not meant to be limiting on the scope of the invention.
It will be apparent that variations and modifications of the disclosed embodiments may be made without departing from the principles of the invention or the scope of the appended claims.
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There is disclosed an air operated demand only hydraulic power unit for supplying hydraulic fluid under presure to one or more hydraulic working motors, comprising an extensible pneumatic power motor including an extensible power transmitting member, an extensible hydraulic slave motor including an extensible slave member powered by said power transmitting member, said slave motor being connected to each said hydraulic working motor to power same, valving for controlling the supply of air and oil to said power and slave motors, and a reset valve for insuring full volume cycling of said slave member in said slave motor. In one embodiment the reset is indicated by sensing the various pressure changes after all working motors are extended and then valving leftover oil to a reservoir. A second embodiment accomplishes the reset on a time delay basis. There is also disclosed an optional intensifier for two-stage operation of said working motors and an optional intensifier for the retract stroke of said power unit to insure full retraction of the hydraulic working motors if so desired. Further included in the disclosure is a mechanism for readily and selectively limiting the working volume of the extensible pneumatic power motors as desired in relation to the number of working motors utilized.
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BACKGROUND OF INVENTION
1. Field of Invention
The present invention relates to a kind of wire cable with saving energy of electric conductor. Especially, it relates to a wire cable of electric conductor able to increase the effect of transportation of electricity and decrease (down low) the producing costs to protect the safety of the users.
2. Description of Prior Art
Owing to the demand of human being increasing, the natural souses in the earth are instantly and quickly consumptive. The resolving ways are positive to recovery the usable souse and restrict the assumption of the various naturally souses. In the modern human beings living, the electricity is extremely important. However, the transportations of electricity demand a large quantity of the metals of copper, aluminum, etc. Thus, if we can not influence the transportation of electricity, the quantity of the above mentioned metals of copper, aluminum, etc. can be decreased. It is nature to reach multiple effects of decreasing of the assumption of souses and also decreasing producing costs so as to increase the economical effects.
According to the handbook of World Electric Engineering Handbook and under general situation, insulated PVC wire cable able to durable 600V of Φ1.6 mm (cross section area 2 mm 2 ), their safe electric current is 20 ampere. That is the cross section area of each 1 mm 2 able to transport electric current of 10 ampere. Obviously, the efficiency of the transportations of electricity of the metal wire cable with larger cross section area is worse. Thus, it is the topic for the related entrepreneur urgently to endeavour diligently, how to increase the efficiency of the transportations of electricity of the metal wire cable with large cross section area and to decrease the use of large quantity of the metals of copper, aluminum.
SUMMARY OF THE INVENTION
Concerning the traditional metal wire cable having the above-mentioned shortcoming, the present invention provides an improvement method in view of these shortcomings. Therefore, the purpose of the present invention is to provide a kind of wire cable with saving energy of electric conductor, which is completely to use the skin effect of metal wire cable so as to increase the quantity and efficiency of transportations of electricity of metal wire cable.
The further purpose of the present invention is to provide wire cable with saving energy of electric conductor. It is able to save the consumption of a large quantity of the metals of copper, aluminum, etc. so as to reduce the production cost effectively and to save natural resources.
Another purpose of the present invention is to provide wire cable with saving energy of electric conductor, by means of ventilating to cool the metal to resist the heat of electrifying, so as to effectively low down the temperature of wire cable while using.
In order to achieve the above mentioned purposes, the present invention provides a kind of wire cable with saving energy of electric conductor comprising: multiple conductors, at least support body (element) along with axial direction to support said wire conductor, an insulator to cover the wire conductor and support body.
Other objects, effects and features will become apparent when the description of preferred embodiments is taken in conjunction with the annexed drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is perspective view of a structure of the wire conductor with a principle hollow circle pipe of the present invention.
FIG. 2 is perspective view of a screw structure of the wire conductor with a principle hollow circle pipe of the present invention.
FIG. 3 is perspective view of the structure of the first aspect of the first embodiment of the present invention.
FIG. 4 is perspective view of the structure of the second aspect of the first embodiment of the present invention.
FIG. 5 is perspective view of the combination of the first embodiment with the terminal of electric conductor of the present invention.
FIG. 6 is a cross sectional view of the structure of the first embodiment of the present invention.
FIG. 7 is perspective view of the combination of the second embodiment with the terminal of electric conductor of the present invention.
FIG. 8 is perspective view of the third embodiment of the present invention.
FIG. 9 is perspective view of the combination of the third embodiment with the terminal of electric conductor of the present invention.
FIG. 10 is perspective view of the combination of the fourth embodiment with the terminal of electric conductor of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Now referring to FIGS. 1 to 5 , these drawings show the structure of embodiment one mainly comprising insulator, hollow pipe with flame-retardant made of flexible material, said hollow pipe can be a round hollow pipe 10 or a sectional flexible pipe 1 or a screw hollow pipe (not shown). While performance (practicing), the conductor 2 is axial direction along with the horizontally direction of the sectional flexible hollow pipe 1 (or round hollow pipe 10 ) so as to be arranged in order at the outside of the sectional flexible hollow pipe 1 (or round hollow pipe 10 ), or these conductors are axial direction by means of screw type along with the horizontally direction of the screw hollow pipe whereby to be arranged in order at the outside of the sectional flexible hollow pipe. Each conductor 2 can be a single core conductor or multiple conductors. It also can be produced by conducting material of copper alumina or alloy. The structure of each conductor 2 is a metal conductor 21 covered with an insulator layer 22 . Each metal conductor 21 is not to contact each other to keep insulating by means of said insulator layer 22 . Further, the outside of each conductor 2 is winding together with an insulating belt 3 (as shown in FIG. 3 ). According to the demand of insulating or protection, the outer circumference of said insulating belt 3 is equipped with another insulator 30 (as shown in FIG. 4 ), so as to form a unit of cable wire A. Finally, the exposed terminal of the metal conductor 21 of each conductor 2 can be compressing or welding connection to connect to a connector 23 , whereby to favor the unit of cable wire A to connect to the outside. Taking advantage of sectional flexible hollow pipe 1 , or round hollow pipe 10 , or screw hollow pipe, the center of each conductor 2 keeps hollowing out with ventilating space, it is convenient to cool metal impedance in electric conduction occurring the heat, so as to reduce the temperature while using. Further, by means of the metal conductor 21 of each conductor 2 not to contact each other, it is able to take advantage of the skin effect of electric conduction, whereby to enhance the power output and transmission efficiency of the unit of cable wire A.
FIG. 6 and FIG. 7 are the structures and performances of the second embodiment. As shown from each drawing, it is known that the structure of the second embodiment is based on the first embodiment. It is to take advantage of multiple cable wire A to line up in order with neighboring, and between each multiple cable wire A, a flexible hollow pipe and insulated filler 40 are equipped, such pipe can be sectional flexible hollow pipe 1 , round hollow pipe 10 or screw hollow pipe, then the most outside flank equipped with together sheathing 4 , finally the terminals of unit of cable wire A, i.e. the exposed terminal of metal conductor 21 of each conductor 2 , are connected to the connector 23 so as to form a bigger structure of cable wire with electric conduction quantity.
FIG. 8 and FIG. 9 are the structures and performances of the third embodiment. As shown from each drawing, it is known that the structure of the third embodiment is mainly the multiple conductors 2 lined up with single layer to form a conductor set 20 and between each conductor set 20 equipped with flat-belt shaped body 5 . At both side of the top and bottom of the flat-belt shaped body 5 , multiple sinking grooves 51 , 52 are arranged and are able to match the outer peripheral shape and arrangement density of conductor 2 to clip and fix each layer of conductor set 20 respectively, so that between each layer of conductor set 20 , a appropriate distance is kept. Simultaneously, further multiple slit fin 53 are horizontally arranged at the center section of flat-belt shaped body 5 and the extending direction of said multiple slit fin 53 is same as that of conductor set 20 to penetrate the flat-belt shaped body 5 . Said multiple slit fin 53 are able to promote the air circulation effect. Finally, the terminal part of conductor set 20 (i.e. the exposed part of metal conductor 21 of the conductor 2 ) can be connected to connector post 24 so as to form another cable wire set structure more larger.
FIG. 10 is perspective view of the combination of the fourth embodiment with the terminal of electric conductor of the present invention. As shown in the drawing, it is well known that the structure of the fourth embodiment is based on that of the first and the third embodiments. It is to take advantage of multiple cable wire A in single layer parallel arrangement to form a cable wire set B. Further, the same structure of flat-belt shaped body 5 is arranged between each cable wire set B (the structure and arrangement of flat-belt shaped body 5 are same as mentioned above). The terminal of each unit of cable wire A can be connected to connector post 23 so as to form another cable wire set structure with electric conduction quantity larger than that of mentioned above in the third embodiment.
The structures mentioned in the above embodiments of the present invention are fully to take advantage of the skin effect of each metal conductor 21 , Simultaneously, said structures equip with hollow and ventilating (sectional flexible hollow pipe 1 , round hollow pipe 10 , screw hollow pipe and slit fin 53 ) to cool down the heat formed by the metal. If it is able to limit the temperature not exceeding 40° C., it will increase the transportation electric quantity massively and effectively (owing to the electric transportation and because of metal impudence, the pass of electric current is able to generate heat. The more electric power, the more resistance, the generation heat is increasing accordingly. Owing to the heat in the conductor being not removed and for safety, it is to limit the temperature not exceeding 40° C. so that the transportation electric quantity can be massively. A big area of metal conductor with 500 mm 2 is done, for example, their safe electric current is 500 ampere inferior to the small area. The safe electric current benefit of metal conductor with 2 mm 2 is high up to 20 ampere. In case, the peripheral of the round flexible pipe is encircled by several insulated single core conductor 2 with 2 mm 2 , or several layers with parallel of insulated conductor 2 are separated a suitable distance respectively whereby to have a good radiation function, under the safe electric current load standard, it is able to several insulated conductor 2 compressed and weld into a connector 23 or 24 , i.e. the total sum of transportation electric current of each insulated conductor 2 . Therefore, it is effective to save wire material of copper/alumina so as to increase the electric transmission power. In case, a painted electric wire or wire enveloped by paint and covered with a slim plastic is used as conductor, it can reduce the electric wire outer diameter and save insulated material, further it is advantageous for the process of construction. For example: the formation of the traditional 500 mm 2 is to use 61 copper wire with Φ3.2 mm, the weight is 4448 Kg per 1000 meter, the safe electric current is 500 ampere. However, the construction of the present invention is to use 25 copper wire with Φ1.6 mm, the safe electric current is also 500 ampere, the weight is 447 Kg per 1000 meter. The load current of the present invention and the tradition one is the same, but in comparison with the present invention and the traditional one, the present invention can save the copper material of 4000 Kg. The benefit is astonishing. Take copper wire with Φ1.6 mm as the example, if is substituted by alumina wire, it is able to increase the cross-section up to 30%. Even the single wire with Φ1.83 mm diameter used, it is still able to transport the safe electric current with 20 ampere. The alumina wire is used to transport electric power with 500 ampere and it is only to use 25 alumina wire with Φ1.83 mm, their weight is 235 Kg per 1000 meter. It is outstanding benefit to save the copper and alumina sources.
The present invention of wire cable with saving energy is able to reduce the production cost, to increase the transportation electric power efficiency and to decrease the temperature increasing effect. The present invention is with the originality and progressive. From the foregoing, it will be appreciated that although the specific embodiments of the invention have been described herein for purposed of illustration, various modifications and improvements thereon will become readily apparent to those skilled in the art. Accordingly, the appended claims are to be construed broadly and in a manner consistent with the spirit and scope of the invention described herein.
DESCIPTION OF SYMBOLS
1 sectional flexible hollow pipe
10 round flexible pipe
2 conductor
20 conductor set
21 metal conductor
22 insulated layer
23 connector post
24 connector post
3 insulating belt
30 insulator
4 sheathing
40 insulated filler
5 flat-belt shaped body
51 sinking grooves
52 sinking grooves
53 slit fin
A unit of cable wire
B cable wire set
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A wire cable of electric conductor forming of multiple metals or alloys includes single (bundle) wire cable or double (bundle) wire cables, in which at least in one bundle of electric conductor, each bundle of electric conductor is composed of slim electric wire made by two or more than two metals or alloys, which is covered by insulator to form a wire cable of electric conductor.
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CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to copending U.S. patent application Ser. No. 11/121,191, filed on May 3, 2005, the entire disclosure of which is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to data transmission and detection in communications networks, and, in particular, to the generation and transmission of an acknowledgment message to inform a transmitter that the receiver successfully received a message from the transmitter.
[0004] 2. Description of the Related Art
[0005] One of the goals in the design of modern mobile communications systems is to increase network throughput, i.e., the bit rate of data traveling over wireless channels. Improvements in throughput can be achieved in a number of ways, e.g., exploiting spatial diversity by using multiple antennas at both the transmitter and receiver sides in a wireless local area network (WLAN), a technique referred to as multiple-input multiple-output (MIMO).
[0006] Improved throughput can also be achieved through a technique known as Quadrature Amplitude Modulation (QAM), whereby a group of buts are “mapped” onto a constellation point on a two-dimensional grid. The x-axis of the grid represents the amplitude of the cosine component in the eventual signal generated based on the constellation point, where as the y-axis represents the amplitude of the sine component in the eventual signal generated based on the constellation point. Accordingly, two amplitude-modulated (AM) signals are effectively combined into a single channel, thereby doubling the effective bandwidth.
[0007] Another method for achieving improved throughput, which may or may not be used in conjunction with MIMO, is orthogonal frequency division multiplexing (OFDM). In OFDM, a wideband channel is divided into narrowband “sub-channels” that are used to multiplex data, such that the center frequencies of the sub-channels (also called “tones” or “subcarriers”) and the symbol durations are chosen to permit maximum packing density of those sub-channels. OFDM can provide very high performance, including a low error rate and a long range, by employing advanced detection schemes at the receiver. One such scheme is Iterative Demodulation/Decoding (IDD), in which soft decisions of all bits of a message are cycled between a MIMO QAM demodulator (or “demapper”) and a sequence decoder. In this manner, the reliability of the soft decisions gradually improves, until hard decisions on each message bit are eventually made in a final iteration. Another advanced detection scheme is Successive Interference Cancellation (SIC), in which parts of a message are hard-decoded, remodulated, and subtracted from the actual antenna signals, resulting in a cleaner signal from which the remaining parts of the message are subsequently demodulated (or “demapped”) and decoded. In MIMO-OFDM, the different parts of a message that are decoded successfully in SIC are typically referred to as “layers,” i.e., signals transmitted from one transmit antenna that arrive at a plurality of receive antennas and overlay linearly with the layers arriving from one or more of the remaining transmit antennas.
[0008] Although the aforementioned advanced detection schemes may provide superior performance, they can introduce significant latency, i.e., processing delay, before the final decisions can be sent to the Medium Access Control (MAC) circuitry. The MAC circuitry performs a Cyclic Redundancy Check (CRC) on the message data it receives before further processing the message. If the CRC check is successful, then the MAC circuitry requests that the modem (or other device receiving the message data) transmit an Acknowledgment (ACK) frame back to the transmitter to confirm that the message was successfully received. If the CRC check fails, then the modem has an indication that an error occurred in the overall transmission. In this case, no ACK frame is transmitted back to the transmitter, and the transmitter attempts to retransmit the message as soon as it regains access to the wireless medium.
[0009] The time span between the last signal component of the incoming data frame and the first signal component of the ACK frame is precisely regulated. According to the IEEE 802.11 standard, this time period, which is referred to as the Short Interframe Spacing (SIFS) period, is 16 microseconds. Even with conventional WLAN transmission formats and detection schemes, this time budget can be very tight because, in addition to the detection, other tasks may need to be performed at the receiver in chronological order. Accordingly, in the event advanced detection schemes are desired for improved performance, the tasks being performed on an incoming message might not be completed in time for the ACK frame transmission.
[0010] Turning now to FIG. 1 , the timing of a conventional process in a WLAN for transmitting a data frame 101 from a first station A to a second station B and for transmitting the corresponding ACK frame 102 from station B back to station A is illustrated. As shown, first, data frame 101 is transmitted from station A to station B. The total amount of time that station B has to switch between reception of data frame 101 and transmission of ACK frame 102 is limited by the SIFS period. During the SIFS period, station B must accomplish all tasks related to the reception of data frame 101 , including determining the integrity of the packet by performing a CRC check. Also during the SIFS period, physical delays, such as those caused by analog radio propagation channel, transmit-to-receive, and receive-to-transmit turnaround times, can occur. The most common cause of these physical delays is transmitter ramp-up, including power amplifier (PA) ramp-up. In the process of FIG. 1 , if the CRC check is successful, then ACK frame 102 is transmitted. If the CRC check is unsuccessful, then no ACK frame is transmitted, thereby causing station A to retransmit data frame 101 at a later time.
[0011] With reference now to FIG. 2 , a PHY (physical layer) frame format of a data frame (e.g., data frame 101 of FIG. 1 ) consistent with the IEEE 802.11a/g standard in an OFDM implementation is shown graphically. As shown, the frame format has a preamble 201 , a signal field 202 , and a data portion 203 . Preamble 201 consists of ten short training symbols t 1 through t 10 a guard interval (GI 2 ), and two long training symbols T 1 and T 2 . Signal field 202 contains a guard interval (GI) and several signaling parameters for the current transmission, e.g., its length and data rate in Mbps. Data portion 203 includes two data symbols, each preceded by a guard interval (GI). While data portion 203 of FIG. 2 has only two data symbols, different numbers of data symbols might be included in an IEEE 802.11 data frame. Included in one or more of the symbols is a MAC frame (shown in further detail in FIG. 3 ), which is described in further detail below.
[0012] FIG. 3 illustrates graphically the MAC frame format of a data frame (e.g., DATA 1 of FIG. 2 ) consistent with the IEEE 802.11 standard. The various fields shown contain the information exchanged between the MAC instances at the transmitter and receiver stations. This information typically includes the access to the medium, addressing, data checking, and data framing. Each MAC instance may hold counters about received and transmitted frames and several timers required for network management. The Address 1 field contains the destination address, and the Address 2 field contains the source address. A receiver that receives a MAC frame tries first to decode the Address 1 field at an early point in time. If it is determined that a different station is the intended recipient, then processing of the remaining portions of the packet is not performed. The frame body field contains the frame data, and a frame checksum (FCS) field appears at the end of the frame for use in verifying whether the frame was correctly received.
[0013] With reference now to FIG. 4 , the format of an exemplary ACK frame (e.g., ACK frame 102 of FIG. 1 ) consistent with the IEEE 802.11 standard is illustrated graphically. As shown, the ACK frame includes fields for frame control, duration, destination receiver address, and frame checksum (FCS).
[0014] FIG. 5 is a timing diagram illustrating an exemplary prior art data flow in a WLAN receiver using OFDM under IEEE 802.11a/g, which data flow corresponds to the role of station B of FIG. 1 . Last-I segment 501 represents the penultimate data symbol of frame 101 of FIG. 1 . Last segment 502 represents the last data symbol of data frame 101 of FIG. 1 . Various analog-to-digital conversion and signal calibration steps (not shown) may be performed on these data symbols. The OFDM data symbol of segment 501 is processed by a Fast Fourier Transformation (FFT) ( 503 ) and demodulation/demapping (and possibly deinterleaving) operations ( 505 ). The OFDM data symbol of segment 502 is processed by an FFT ( 504 ) and demodulation/demapping (and possibly deinterleaving) operations ( 506 ). The result of this processing is a set of “soft bits” (i.e., likelihood values) that are forwarded to a Vitterbi decoder 507 , which, based on the sequence of soft bits, generates the most likely message of information bits and forwards the message, bit by bit, to MAC circuitry 508 , where the CRC check is carried out. If the CRC check is successful, then the message is forwarded to higher communication layers (e.g., TCP/IP), and ACK frame 102 is transmitted. The CRC check result is available a sufficient amount of time before the end of the SIFS period to enable ramp-up of the transmitter (e.g., the power amplifier) by the end of the SIFS period.
[0015] FIG. 6 is a state diagram illustrating exemplary states of a state machine in a prior art WLAN receiver using OFDM, wherein the state machine is embodied in a receiver corresponding to the role of station B of FIG. 1 , whose data flow is illustrated in FIG. 5 . The states include Idle state 601 , Receive Data & Send to MAC state 602 , Transmit ACK frame state 603 , and Wait states 604 and 605 . The state machine begins in Idle state 601 and remains there until a packet is detected, in which case Receive Data & Send to MAC state 602 is entered. In Receive Data & Send to MAC state 602 , detection and CRC checking are performed. If, during the detection process, it is determined that the MAC destination address (Address 1 field in FIG. 3 ) reveals that the packet is intended for another station, then the present station will revert to Idle state 601 . This reversion might not occur until a time trigger is issued that the channel is once again usable, the wait for the time trigger being represented by Wait state 605 . If the MAC destination address reveals that the packet is indeed intended for the present station, then the detection process continues. Once detection is complete, if the CRC check fails, then the state machine returns to Idle state 601 . If it is determined that the CRC check is successful, then the state machine enters Wait state 604 until the end of the SIFS period, at which time Transmit ACK frame state 603 is entered, and the ACK frame is transmitted. Once the ACK frame is complete, the state machine returns to Idle state 601 . The amount of time spent in Wait state 604 between the outcome of the CRC check and the time trigger to send the ACK frame might be rather limited, due to the large number of tasks that need to be carried out during the SIFS period and which cannot always be parallelized. The station acting as a receiver in the present transmit request can transmit its own frames as well, in which case, in the initial Idle state 601 , the receiver would undergo other states, not shown in FIG. 6 or described herein.
[0016] FIG. 7 shows an exemplary hardware configuration 701 for a high-performance detection scheme employing Iterative Demapping/Decoding (IDD) in a WLAN receiver using OFDM. The transmit scheme corresponding to this mechanism is referred to as Space-Time Bit-Interleaved Coded Modulation (ST-BICM). Symbols received at antennas 702 - 1 , 702 - 2 are provided to preprocessing circuitry 703 , which includes, e.g., performing Fast Fourier Transformations. The output of preprocessing circuitry 703 is provided to a MIMO demapper 704 , which generates, for each bit coded into a MIMO-ODFM subcarrier (e.g., using QAM modulation), a soft bit using the signals from the channel that are received at antennas 702 - 1 , 702 - 2 , and possibly also using extrinsic information obtained from a Maximum A Posteriori (MAP) decoder 707 . In the first iteration, no extrinsic information is yet available, so the soft bits are generated based solely on the signals received at antennas 702 - 1 , 702 - 2 . Next, the soft bits are provided to a deinterleaver 705 to be deinterleaved. MAP decoder 707 then uses the information provided by deinterleaver 705 and the properties of the (convolutional) channel code to produce improved soft bits. The extrinsic information, i.e., the estimate of each bit provided by MAP decoder 707 , is passed back to demapper 704 after being re-interleaved by interleaver 706 , which provides its output to demapper 704 . Demapper 704 can now use this extrinsic information to improve the demapping process, thereby producing further-improved soft bits. The decoding process repeats until the iterative process is complete and hard bits are generated as the output of MAP decoder 707 .
[0017] With reference now to FIG. 8 , the temporal succession of the various demapping/decoding and deinterleaving/interleaving iterations in the exemplary hardware configuration of FIG. 7 is shown. As can be seen, the first iteration receives raw samples from the Fast Fourier Transform circuitry. Each iteration involves demapping, deinterleaving, decoding, and interleaving, except for the final iteration, which involves only demapping, deinterleaving, decoding, and a final step of making hard-bit decisions of the data contained in the message.
[0018] FIG. 9 illustrates another exemplary hardware configuration 901 for a high-performance detection scheme. The transmit scheme corresponding to this mechanism is referred to as Vertical Bell Labs Layered Space-Time (V-BLAST) code modulation. In this scenario, a single signal “layer” (i.e., the bits corresponding to a (QAM) symbol transmitted from only one of the several transmit antennas) at a time is initially demapped, while the signal components corresponding to the (QAM) symbols from other transmit antennas also present are temporarily ignored. Then, MIMO Layer-I is deinterleaved and Viterbi-decoded in a conventional manner. The results of the Viterbi decoding are used to reconstruct the actual receive signals of Layer-1, using knowledge of the exact channel state (i.e., phase and magnitude between each transmit antenna-receive antenna pair, per OFDM subcarrier). This reconstructed symbol for MIMO Layer-1 is subtracted from the overall input signal, thereby providing a “cleaner” signal for detection of Layer-2.
[0019] Accordingly, symbols received at antennas 902 - 1 , 902 - 2 are provided to preprocessing circuitry 903 , which performs, e.g., Fast Fourier Transformations. The output of preprocessing circuitry 903 is provided to MIMO demapper 904 - 1 , which generates, for each bit coded into the MIMO-ODFM subcarrier (e.g., using QAM modulation), a soft bit using the signals that are received at antennas 902 - 1 , 902 - 2 , and possibly also using extrinsic information obtained from Viterbi decoder 907 - 1 . In the first iteration, no extrinsic information is yet available, so the soft bits are generated based solely on the signals received at antennas 902 - 1 , 902 - 2 . The output from preprocessor 903 is also provided to delay circuits 909 - 1 , 909 - 2 , which, after one symbol period T. provide the preprocessed signals to subtractors 908 - 1 , 908 - 2 . The soft bits generated by demapper 904 - 1 are provided to deinterleaver 905 - 1 to be deinterleaved. Viterbi decoder 907 - 1 then uses the information provided by deinterleaver 905 - 1 and the properties of the (convolutional) channel code to produce improved soft bits, which Viterbi decoder 907 - 1 outputs as the decoded MIMO Layer-1 data. The “extrinsic information” is generated by the information bits provided by Viterbi decoder 907 - 1 , which are channel re-encoded and interleaved by encoding interleaver 906 , which provides its output to a remodulator KK. Remodulator KK translates the bit stream into complex symbol format, e.g., QAM. The output of remodulator KK is provided to subtractors 908 - 1 , 908 - 2 , each of which provides a signal representing the reconstructed Layer-i signal subtracted from one of the received input signals, which resulting difference signal is a “cleaner” signal (i.e., due to the removal of the Layer-i data) that is then provided to MIMO demapper 904 - 2 for demapping. Using the “cleaner” signal, demapper 904 - 2 provides soft bits to deinterleaver 905 - 2 , which deinterleaves the soft bits and provides its output to Viterbi decoder 907 - 2 . Viterbi decoder 907 - 2 provides the decoded MIMO Layer-2 data as its output.
[0020] Turning now to FIG. 10 , a timing diagram illustrating the latency problem in an exemplary prior art WLAN receiver data flow using OFDM is presented. Last-I segment 501 represents the penultimate data symbol of frame 101 of FIG. 1 . Last segment 502 represents the last data symbol of data frame 101 of FIG. 1 . Various analog-to-digital conversion and signal calibration steps (not shown) may be performed on these data symbols. The OFDM data symbol of segment 501 is processed by an FFT ( 1003 ) and demodulation/demapping (and possibly deinterleaving) operations ( 1005 ). The OFDM data symbol of segment 502 is processed by an FFT ( 1004 ) and demodulation/demapping (and possibly deinterleaving) operations ( 1006 ). The detected symbols are forwarded to MAC circuitry 1007 , where the CRC check is carried out. If the CRC check is successful, then the message should be forwarded to higher communication layers (e.g., TCP/IP), and an ACK frame 102 should be transmitted. However, as can be seen, the SIFS period is not long enough to accommodate the more-involved DSP processing, the delayed completion of the CRC check, and other possible tasks relating to the packet reception. The time required for transmitter ramp-up further aggravates this problem. Accordingly, by the time the CRC check is determined to be successful, it is too late to send ACK frame 102 .
[0021] Prior art solutions to this latency problem include avoiding the use of advanced, high-performance detection schemes or using fewer iterations in an iterative scheme. These solutions, however, result in decreased performance in terms of packet error rate (PER), effectively leading to lower throughput, which results in lower physical data rates and/or a shorter range between the transmitter and the receiver. Other solutions involve (i) using faster clock speeds and (ii) using parallel processing by employing relatively large-scale circuitry. However, these solutions typically result in increased power consumption and increased fabrication cost for the circuitry.
SUMMARY OF THE INVENTION
[0022] Problems in the prior art are addressed in accordance with the principles of the present invention by beginning transmission of an ACK frame before the CRC check is finalized and employing techniques for modifying the ACK frame. Accordingly, if the CRC check fails due to an erroneous frame, then the remaining parts of the ACK frame being transmitted are modified, e.g., prematurely terminated or altered, so as to cause retransmission of the data frame.
[0023] In one embodiment, the present invention provides a method for processing a received encoded data unit. The method comprises: decoding the received encoded data unit; determining whether the encoded data unit has been correctly received; prior to completing the determination of whether the encoded data unit has been correctly received, initiating the transmission of an acknowledgment message; and modifying the transmission of the acknowledgment message if it is determined that the data unit has not been correctly received.
[0024] In another embodiment, the present invention provides a station for a communications network. The station comprises: a decoder adapted to decode a received encoded data unit; a check processor adapted to determine whether the encoded data unit has been correctly received; and a transmitter adapted to initiate the transmission of an acknowledgment message prior to the check processor completing the determination whether the encoded data unit has been correctly received. The transmitter is adapted to modify the transmission of the acknowledgment message if the check processor determines that the data unit has not been correctly received.
[0025] In a further embodiment, the present invention provides a machine-readable medium, having encoded thereon program code, wherein, when the program code is executed by a machine, the machine implements a method for processing a received encoded data unit. The method comprises: decoding the received encoded data unit; determining whether the encoded data unit has been correctly received; prior to completing the determination of whether the encoded data unit has been correctly received, initiating the transmission of an acknowledgment message; and modifying the transmission of the acknowledgment message if it is determined that the data unit has not been correctly received.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Other aspects, features, and advantages of the present invention will become more fully apparent from the following detailed description, the appended claims, and the accompanying drawings in which like reference numerals identify similar or identical elements.
[0027] FIG. 1 is a timing diagram illustrating a prior art method for transmitting (i) a data frame from a first station to a second station and (ii) an ACK frame from the second station to the first station;
[0028] FIG. 2 is a graphic illustration of a PHY frame format consistent with the IEEE 802.11a/g standard in an OFDM implementation;
[0029] FIG. 3 is a graphic illustration of a MAC frame format consistent with the IEEE 802.11 standard;
[0030] FIG. 4 is a graphic illustration of an ACK frame format consistent with the IEEE 802.11 standard;
[0031] FIG. 5 is a timing diagram illustrating an exemplary prior art data flow in a WLAN receiver using OFDM;
[0032] FIG. 6 is a state diagram illustrating exemplary states of a state machine in a prior art WLAN receiver using OFDM;
[0033] FIG. 7 is a block diagram illustrating an exemplary hardware configuration for a high-performance detection scheme employing Iterative Demapping/Decoding (IDD) in a WLAN receiver using OFDM;
[0034] FIG. 8 is a graphic representation of the temporal succession of the various demapping/decoding and deinterleaving/interleaving iterations in the exemplary hardware configuration of FIG. 7 ;
[0035] FIG. 9 is a block diagram illustrating an exemplary hardware configuration for a high-performance detection scheme employing Vertical Bell Labs Layered Space-Time (V-BLAST) code;
[0036] FIG. 10 is a timing diagram illustrating the latency problem in an exemplary prior art data flow in a WLAN receiver using OFDM;
[0037] FIG. 11 is a timing diagram illustrating a first exemplary method, consistent with one embodiment of the present invention, for transmitting (i) a data frame from a first station to a second station and (ii) an ACK frame from the second station to the first station, wherein the ACK frame is modified by prematurely terminating the ACK frame if the CRC check has failed;
[0038] FIG. 12 is a state diagram illustrating exemplary states of a state machine implementing the exemplary method of FIG. 11 ;
[0039] FIG. 13 is a timing diagram illustrating the exemplary method of FIG. 11 in a detection scheme employing Iterative Demapping/Decoding (IDD);
[0040] FIG. 14 is a timing diagram illustrating a second exemplary method, consistent with one embodiment of the present invention, for transmitting an ACK frame, wherein the ACK frame is manipulated if the CRC check has failed;
[0041] FIG. 15 is a timing diagram illustrating a first variation of the exemplary method of FIG. 14 , wherein the ACK frame is modified by changing the MAC destination address in the ACK frame body;
[0042] FIG. 16 is a timing diagram illustrating a second variation of the exemplary method of FIG. 14 , wherein the ACK frame is modified by corrupting one of the bits in the ACK frame body; and
[0043] FIG. 17 is a state diagram illustrating exemplary states of a state machine implementing the exemplary method of FIG. 14 .
DETAILED DESCRIPTION
[0044] In a typical WLAN decoding scheme, a station (e.g., a receiver, modem, or similar device) detects an incoming packet (e.g., a data frame) and, by reading the destination Medium Access Control (MAC) address in the frame header, determines whether it is the intended recipient. If so, and if the station determines that the incoming packet was received intact (e.g., via a CRC check), then the station transmits an acknowledgment (ACK) frame back to the transmitting station. In a decoding scheme consistent with the present invention, the transmission of the ACK frame is initiated at the expiration of the Short Interframe Spacing (SIFS) period, even if the CRC check has not yet returned its result. In the meantime, the packet detection (e.g., using Iterative Demapping/Decoding (IDD) or Successive Interference Cancellation (SIC)) and CRC check are finalized. If the CRC check is successful, then normal transmission of the ACK frame is completed. However, if the CRC check fails, then the ACK frame is modified from its proper form either (i) by terminating the ACK frame prematurely or (ii) by altering the remaining portion of the ACK frame. In either case, the modified ACK frame will cause the transmitter to retransmit the data frame to the station at a later time. Accordingly, advanced detection schemes for wireless LANs, such as in the case of MIMO-OFDM, can achieve throughput efficiency with fewer latency problems, thereby potentially increasing either range, data transfer rates, or both.
[0045] Turning now to FIG. 11 , a timing diagram is provided for a first exemplary method, consistent with one embodiment of the present invention, for transmitting (i) a data frame from a first station to a second station and (ii) an ACK frame from the second station back to the first station, wherein the ACK frame is prematurely terminated if the CRC check has failed. As can be seen, first, a data frame 1101 is transmitted from station A to station B. The total amount of time that station B has to switch between reception of data frame 1101 and transmission of ACK frame 1102 is limited by the SIFS period. During the SIFS period, station B would ordinarily have to accomplish all tasks related to the reception of data frame 1101 , including (i) performing frame detection using advanced detection schemes and (ii) determining the integrity of the packet by performing a CRC check on the overall frame. However, in the process of FIG. 11 , assuming that the packet has the correct destination address (i.e., station B), the transmission of ACK frame 1102 begins before the detection processing and the CRC check have been completed. When the CRC check is complete, it can be seen in FIG. 11 that a portion of ACK frame 1102 has already been transmitted.
[0046] Once the CRC check result is available, which is before the overall completion of transmission of ACK frame 1102 , station B can react accordingly. In case (a), the CRC check is passed, and the remainder of ACK frame 1102 is transmitted, signaling to station A that station B successfully received the data frame. In case (b), the CRC check is unsuccessful, and transmission of ACK frame 1102 is prematurely terminated, such that only a partial ACK frame 1102 ′ is transmitted. Since the ACK frame is incomplete, no complete ACK frame is ever received, and station A generates a time-out and will retransmit data frame 1101 at a later time. If the frame is destined for a station other than station B, then the transmission of an ACK frame is not initiated by station B.
[0047] FIG. 12 is a state diagram illustrating exemplary states of a state machine in a WLAN receiver using OFDM in the exemplary method of FIG. 11 , wherein the state machine is embodied in a receiver corresponding to the role of station B of FIG. 11 . The states include Idle state 1201 , Receive and Detect Data & Send to MAC state 1202 , Start ACK frame and Continue Processing and Forwarding Data state 1203 , Finish ACK frame state 1204 , and Wait state 1205 . The state machine begins in Idle state 1201 and remains there until a packet is detected, in which case Receive and Detect Data & Send to MAC state 1202 is entered. In Receive and Detect Data & Send to MAC state 1202 , detection and CRC checking are performed. If during the detection process, it is determined that the MAC destination address (e.g., Address 1 field in FIG. 3 ) reveals that the packet is intended for another station, then the present station will revert to Idle state 1201 . This reversion might not occur until a time trigger is issued that the channel is once again usable, the wait for the time trigger being represented by Wait state 1205 . If the MAC destination address reveals that the packet is indeed intended for the present station, then the detection process continues. Before the completion of the detection process and CRC check, Start ACK frame and Continue Processing and Forwarding Data state 1203 is entered, the ACK frame transmission is initiated, and processing continues. If it is determined that the CRC check has failed, then the state machine returns to Idle state 1201 , and the ACK frame transmission is not completed. If it is determined that the CRC check is successful, then the state machine enters Finish ACK frame state 1204 , and the remainder of the ACK frame is transmitted. Once the ACK frame is complete, the state machine returns to Idle state 1201 . It is noted that, instead of remaining in a wait state pending the detection and the outcome of the CRC check (as in prior art FIG. 6 ), the detection and CRC check continue while the ACK frame transmission begins. It is further noted that the station acting as a receiver can transmit its own frames as well; in this case, in the initial Idle state 1201 , the receiver would undergo other states, not shown in FIG. 12 or described herein.
[0048] FIG. 13 is a timing diagram illustrating the exemplary method of FIG. 11 in a detection scheme employing Iterative Demapping/Decoding (IDD), wherein the data flow shown corresponds to the role of station B of FIG. 11 . Last-1 segment 1307 represents the penultimate data symbol of the data frame currently being decoded. Last segment 1308 represents the last data symbol of the data frame currently being decoded. Various analog-to-digital conversion and signal calibration steps (not shown) may be performed on these data symbols. The OFDM data symbol of segment 1307 is processed by an FFT ( 1301 ) and demodulation/demapping (and possibly deinterleaving) operations ( 1303 - 1 , 1303 - 2 , 1303 - 3 , 1303 - 4 ). The OFDM data symbol of segment 1308 is processed by an FFT ( 1302 ) and demodulation/demapping (and possibly deinterleaving) operations ( 1304 - 1 , 1304 - 2 , 1304 - 3 , 1304 - 4 ). During the iterative detection process, the detected symbols are forwarded to MAC circuitry 1305 , where the CRC check is carried out. As shown, transmission of ACK frame 1306 begins before the completion of the iterative detection process. If the CRC check is successful, then the message should be forwarded to higher communication layers (e.g., TCP/IP), and the remainder of ACK frame 1306 is transmitted. If the CRC check is unsuccessful, then ACK frame 1306 is never completed, so that the data frame will be retransmitted.
[0049] As illustrated in the timing diagram of FIG. 14 , in a second exemplary method consistent with one embodiment of the present invention, instead of prematurely terminating ACK frame 1401 , the bits of ACK frame 1401 are altered if the CRC check fails. As shown, once the outcome of the CRC check is available, transmission of the intentionally corrupted (or “poisoned”) ACK frame 1401 is completed. When the transmitting station receives corrupted ACK frame 1401 , it will retransmit the original data frame. For certain implementations, this scheme may provide advantages over the use of a prematurely terminated ACK frame, because energy is “on the air” for the amount of time corresponding to a true ACK frame, to prevent other stations (i) from being “confused” by the unexpected drop in energy in the medium and (ii) from entering a medium access recovery mode. While a variety of ways for modifying the ACK frame are possible, any modification of bits in the ACK frame body that leads to inconsistencies between the detected data and the ACK frame checksum at the transmitter will cause the transmitter's CRC check to fail and the original frame to be retransmitted. Two exemplary modifications are discussed below:
[0050] FIG. 15 is a timing diagram illustrating a first variation of the exemplary method of FIG. 14 , wherein the ACK frame is manipulated by changing the MAC destination address in ACK frame body 1502 . The method is similar to that illustrated in FIGS. 11-13 , in that the transmission of ACK frame header 1501 is initiated before the CRC check result is available. However, upon detection that the CRC check has failed, instead of prematurely terminating the ACK frame, the MAC destination address (field Address 1 ) in body 1502 of the ACK frame is changed from the original transmitting station (station A) to a replacement address. For example, the replacement address can be the address of a non-existing, dummy station, or alternatively, the address of the receiving station itself (station B). Accordingly, no other station will be addressed by the ACK frame, and station A will eventually initiate a retransmission of the lost data frame.
[0051] FIG. 16 is a timing diagram illustrating a second variation of the exemplary method of FIG. 14 , wherein the ACK frame is manipulated by corrupting one or more of the bits in ACK frame body 1602 . The method is similar to that illustrated in FIGS. 11-13 , in that the transmission of ACK frame header 1601 is initiated before the CRC check result is available. However, upon detection that the CRC check has failed, instead of prematurely terminating the ACK frame, one or more of the bits in ACK frame body 1602 are rearranged or modified. For example, the Frame Checksum (FCS) used for the CRC check in conjunction with the ACK frame could be altered. Accordingly, upon performing a CRC check on the ACK frame, station A will drop the ACK frame due to the lack of CRC check confirmation and will eventually initiate a retransmission of the lost data frame.
[0052] FIG. 17 is a state diagram illustrating exemplary states of a state machine in a WLAN receiver using OFDM in the exemplary method of FIG. 14 , wherein the state machine is embodied in a receiver corresponding to the role of station B of FIG. 11 . The states include Idle state 1701 , Receive and Detect Data & Send to MAC state 1702 , Start ACK frame and Continue Processing and Forwarding Data state 1703 , Finish ACK frame state 1704 , Wait state 1705 , and Corrupt and Finish ACK frame state 1706 ′. The state machine begins in Idle state 1701 and remains there until a packet is detected, in which case Receive and Detect Data & Send to MAC state 1702 is entered. In Receive and Detect Data & Send to MAC state 1702 , detection and CRC checking are performed. If, during the detection process, it is determined that the MAC destination address (e.g., Address 1 field in FIG. 3 ) reveals that the packet is intended for another station, then the present station will revert to Idle state 1701 . This reversion might not occur until a time trigger is issued that the channel is once again usable, the wait for the time trigger being represented by Wait state 1705 . If the MAC destination address reveals that the packet is indeed intended for the present station, then the detection process continues. Before the completion of the detection process and CRC check, Start ACK frame and Continue Processing and Forwarding Data state 1703 is entered, the ACK frame transmission is initiated, and processing continues. If it is determined that the CRC check has failed, then the state machine enters state 1706 , and the contents of the ACK frame transmission are manipulated, as described above with reference to FIGS. 14-16 . If it is determined that the CRC check is successful, then the state machine enters Finish ACK frame state 1704 , and the remainder of the normal, uncorrupted ACK frame is transmitted. Once the transmission of either the corrupted ACK frame in state 1706 or the uncorrupted ACK frame in state 1704 is complete, the state machine returns to Idle state 1701 . Instead of remaining in a wait state pending the detection and the outcome of the CRC check (as in prior art FIG. 6 ), the detection and CRC check continue while the ACK frame transmission begins. It is further noted that the station acting as a receiver in the present transmit request can transmit its own frames as well, in which case, in the initial Idle state 1701 , the receiver would undergo other states, not shown in FIG. 17 or described herein.
[0053] It is contemplated that a transceiver or modem device implementing a method consistent with the present invention would have hooks for starting to transmit a packet, i.e., the ACK frame, while still completing the detection process for the incoming packet. One exemplary method of accomplishing these tasks in parallel involves preparing the “good ACK frame” and the “corrupted ACK frame” in the background, e.g., by storing the corresponding time samples in memory. Then, the “good ACK frame” samples are used to start the ACK frame transmission, and as soon as it is determined that the CRC check has failed, the “corrupted ACK frame” time samples can be switched onto the transmitter circuitry.
[0054] It should be recognized that a method consistent with the present invention may be used to further shorten the SIFS period time in future WLAN implementations. The PHY header (i.e., preamble, etc.) that forms the early parts of every packet, including ACKs, takes 20 microseconds in current WLAN implementations, and is expected to take longer in future implementations. If, as in the present invention, this time can be used to finalize advanced detection mechanisms before the rest of the ACK frame is either transmitted as normal, or terminated or corrupted as described herein, then performance advantages may be expected for high-speed detection schemes. Accordingly, the present invention may facilitate a high-performance system with high throughput efficiencies due to the reduced SIFS period time, which is an important component of system overhead.
[0055] The present invention should be construed as including any method of modifying an acknowledgment message, e.g., terminating the acknowledgment message prematurely, adding bits to or removing bits from the acknowledgment message, modifying the message header, modifying the message body, modifying the message destination address, modifying the CRC value, etc.
[0056] It should be recognized that the present invention should not be construed as limited to any particular frame format, e.g., PHY formats for high-speed transmission using advanced MIMO technology, and that it is contemplated that the present invention can be applied to any existing frame formats, as well as those that have not yet been developed. The present invention may also be used with signaling schemes other than OFDM.
[0057] Although the present invention is described as implemented in a WLAN, the present invention may also have utility in hardwired implementations, as well as in non-networked wireless communications systems.
[0058] While the present invention is described herein as involving the transmission of packets, frames, and messages, the invention may alternatively be embodied in a manner so as to involve the transmission of other data units.
[0059] Likewise, although the invention is described herein as employing ACK frames as acknowledgment messages, other forms of acknowledgment messages may be possible in other embodiments of the invention.
[0060] The present invention may be implemented as circuit-based processes, including possible implementation as a single integrated circuit (such as an ASIC or an FPGA), a multi-chip module, a single card, or a multi-card circuit pack. Various functions of circuit elements may also be implemented as processing steps in a software program. Such software may be employed in, for example, a digital signal processor, micro-controller, or general-purpose computer.
[0061] Unless explicitly stated otherwise, each numerical value and range should be interpreted as being approximate, as if the word “about” or “approximately” preceded the value of the value or range.
[0062] It will be further understood that various changes in the details, materials, and arrangements of the parts which have been described and illustrated in order to explain the nature of this invention may be made by those skilled in the art without departing from the scope of the invention as expressed in the following claims.
[0063] Although the steps in the following method claims, if any, are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those steps, those steps are not necessarily intended to be limited to being implemented in that particular sequence.
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A station for a communications network. In one embodiment, the station includes a decoder, a check processor, and a transmitter. The decoder is adapted to decode a received encoded data unit. The check processor is adapted to determine whether the encoded data unit has been correctly received. The transmitter is adapted to initiate, prior to the check processor completing the determination whether the encoded data unit has been correctly received, the transmission of an acknowledgment message comprising a frame having a plurality of different fields of data. The transmitter is adapted to modify the transmission of the acknowledgment message if the check processor determines that the data unit has not been correctly received.
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BACKGROUND OF THE INVENTION
The present invention relates to an improved sized warp divider for a sizing machine, and more particularly relates to an improved construction of a sized warp divider in which sized warps are horizontally divided during passage through spaces formed by coaxially juxtaposed rotary divider discs.
Generally on a sizing machine, warps are delivered from warp beams in the supply station, passed through a sizing bath provided with immersion and squeeze rollers, and led to a dryer station after dividing by a suitable sized warp divider arranged between the sizing and dryer stations of the sizing machine.
For dividing of sized warps, the conventional warp divider is provided with a transverse divider rod arranged horizontally across the travelling path of the warps and a transverse comb arranged horizontally on the downstream side of the dividing rod. The upstream dividing rod divides the warps vertically into upper and lower warp sheets whereas the teeth of the downstream comb divide the warp sheets horizontally into individual, juxtaposed warps. Since warp dividing is carried out when the warps are still in a wet state, liquid size on the warps clings to the dividing rod and the teeth of the comb and is solidified by the heat from the dryer station which is usually located very close to the sizing station of the machine. Solidified size dregs on the dividing rod and the teeth of the comb seriously damage the warps which have running contact with these elements.
In order to obviate such a trouble, a new type of warp divider is disclosed in the Japanese Utility Model Publication Sho. 48-9150. This new arrangement includes a plurality of juxtaposed divider discs mounted to a rotary shaft which extends in a direction normal to the travelling direction of warps so that a warp or warps pass through a spaoe between adjacent divider discs. Water is sprayed on the divider discs in order to prevent solidification by heat of the liquid size clinging to the divider discs, thereby avoiding damage to the processed warps.
In this case, however, size dregs are always accumulated on the divider discs. These size dregs on the divider discs may often be taken over by the warps which have running contact with the divider discs, and are solidified while passing through the next-stage dryer station. Presence of such size dregs on the warps tends to cause frequent yarn breakgage during weaving and formation of weaving defects in the products.
In addition, forcible warp dividing by the divider discs blemished with size dregs promotes separation of fluffs from the warps and these fluffs cling to the faces of the divider discs which have sliding contact with the warps. This fluffs separation is remarkable in the case of spun yarns. Presence of such fluffs on the divider discs seriously damages the warps, in general and particularly when they are mixed with the size dregs.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a sized warp divider which greatly minimizes damage on warps caused during warp dividing on a sizing machine.
It is another object of the present invention to provide a sized warp divider capable of making fluffs, which have been caused by forcible warp dividing, lay flatly on the surface of the warps, this apparatus being particularly suited for sizing of spun yarns.
It is the still another object of the present invention to provide a divider disc type sized warp divider which well prevents uneven sizing and drying effects conventionally caused by presence of liquid drops in spaces between adjacent divider discs.
It is a further object of the present invention to provide a sized warp divider which assures ideal and complete warp dividing without any operational trouble such as yarn breakage during processing.
In accordance with the present invention, the sized warp divider includes a transverse rotary shaft arranged between the sizing and dryer sections of a sizing machine while extending in a direction substantially normal to the travelling direction of warps, and a plurality of parallel divider discs coaxially mounted on the rotary shaft at substantially equal intervals in an arrangement engageable with warps passing through spaces between adjacent divider discs. The level of the rotary shaft is chosen so that, as the rotary shaft is driven for operation, the circular section of each divider disc is sequentially placed in liquid in a wash bath arranged under the rotary shaft in which the liquid is forced to flow. The divider discs are accompanied with means for applying an air jets to the spaces between adjacent divider discs at a position over the level of the liquid.
Preferably, the driving system for the rotary shaft is separated, for independent operation control, from that for the sizing machine.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view, partly in section, of one embodiment of the sized warp divider in accordance with the present invention and its related parts of a sizing machine.
FIG. 2 is a plan view of the sized warp divider shown in FIG. 1, and
FIG. 3 is a perspective view, partly removed and omitted for easy understanding, of the sized warp divider shown in FIG. 1.
FIG. 4 is a perspective view, partly removed and omitted for easy understanding, of the sized warp divider shown in FIG. 1 including an alternate arrangement for the barring rod of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
One embodiment of the sized warp divider 5 in accordance with the present invention is shown with its related parts of the sizing machine in FIGS. 1 through 3.
In the arrangement shown in FIG. 1, warps Y to be sized are delivered from warp beams (not shown), arranged in the supply station of the sizing machine, and are led to the sizing station 3, in which the warps Y are dipped by an immersion roller 33 in a size bath P within a sizing box 35. After the immersion, the warps Y are passed through the nip between a pair of squeezing rollers 31 and 32 for removal of excessive size, and are divided into upper and lower sheets by a dividing rod 4 extending transversely across the travelling path of the warps.
The warps Y, divided into two sheets, are then led to the sized warp divider 5 of the present invention. After division by the divider 5, the warps Y are further led to the dryer station 7 of the sizing machine, in which heated drums 71 are arranged.
Thus, the sized warp divider 5 of the present invention is arranged on the upstream side of the dryer station 7 along the travelling path of the warps Y. The warp divider 5 includes a wash bath 56, containing proper liquid W such as water, which is arranged under the travelling path of the warps Y. The warp divider 5 further includes a rotary shaft 53 extending in the width direction of the warp sheets. A plurality of parallel divider discs 51 are coaxially secured to the roatry shaft 53 at equal intervals, while extending in the travelling direction of the warp sheet. The dimension of the intervals should properly be designed in accordance with the warp density on the sizing machine. In practice, the distance between adjacent divider discs 51 should preferably be in a range from 1.4 to 4 mm. in order to allow free passage of one or two warps Y. The level of the rotary shaft 53 is designed so that the warps Y pass the space between adjacent discs 51, partly in contact with the divider discs 51, at a level of about two-thirds of the radius of the divider discs 51 above the axis of the rotary shaft 53. In practice, the warp sheet level is about 50 mm. above the axis of the rotary shaft 53 when the diameter of the divider disc 51 is about 75 mm.
The level of the rotary shaft 53 is further designed so that the circular section of each divider disc 51, which contacts with the warp or warps Y passing by, should sequentially be placed under the level of the liquid W in the wash bath 56 when the divider discs 51 rotate with the shaft 53 in the travelling direction of the warps Y and the diametral section comes on the lower side of the rotary shaft 53. Thus, size dregs and fluffs taken over by the divider discs 51 through contact with the warps Y are removed therefrom through contact with the liquid W in the bath 53 as the discs 51 rotate with the shaft 53.
As a consequence, the liquid W in the bath 56 is contaminated with the size dregs and fluffs falling off the divider discs 51 on the shaft 53. In order to prevent such contamination of the liquid W, fresh liquid has to be always supplied into the wash bath 56 and the size dregs and fluffs have to be always removed from the wash bath 56. To this end, a liquid supply tube 52 is arranged within the wash bath 56 at a position below the level of the liquid W and in parallel to the rotary shaft 53. The liquid supply tube 52 is provided with a plurality of radial openings 52a directed towards the divider discs 51 on the shaft 53 for formation of jet flow within the bath 56. On the side of the divider discs 51 opposite to the liquid supply tube 52, an overflow drain 59 is arranged within the wash bath 56 for constant discharge of liquid contaminated with size dregs and fluffs outside the wash bath 56. It should be appreciated that the jet flow generated by the liquid supply tube 52 completely removes size dregs and fluffs on the divider discs 51 into the liquid W within the wash bath 56.
After removal of size dregs and fluffs within the wash bath 56, the diametral section of each divider disc 51 leaves the level of the liquid as the divider discs 51 further rotate. Due to the extremely small distance between adjacent divider discs 51, the space between the adjacent divider discs 51 may contain liquid drops formed by surface tension of the liquid W even after its separation from the liquid W in the wash bath 56.
Presence of such liquid drops in the space between adjacent divider discs 51 is liable to cause surplus adsortion of the liquid W by the warp or warps Y passing through the space. This surplus adsorption of liquid leads to variation of size at the spots of the warps Y where the liquid is adsorbed and uneven drying in the next-staged dryer station 7.
In order to prevent presence of such liquid drops in the space between adjacent divider discs 51, the warp divider 5 in accordance with the present invention further includes an air ejection tube 54 arranged in parallel to the rotary shaft 53 and just above the level of the liquid W in the wash bath 56. Further, the air ejection tube 54 is located on the upstream side of the divider discs 51 on the shaft 53, and provided with a plurality of openings directed towards the divider discs 51 for ejection of air jet flow, thereby blowing off liquid drops in the spaces between the divider discs 51 before contact of the divider discs 51 with the warps Y.
The warps Y from the sizing station 3 are vertically divided by the dividing rod 4 into the upper and lower sheets and introduced into the warp divider 5 of the present invention in order to be further horizontally divided into individual warps Y by passage through the spaces between the cleaned divider discs 51 on the rotary shaft 53. During this horizontal dividing, insufficient tension on adjacent warps may cause the warps to climb over the top periphery of an assooiated divider disc 51 and the warps are not divided horizontally into individual warps. In order to prevent such faulty dividing, a barring rod 57 is arranged in parallel to the rotary shaft 53, on the upstream side of the divider discs 51 and at a level above the warp sheets and below the top peripheries of the divider discs 51. This barring rod 57 effectively blocks excessive upward movement of the warps Y travelling through the warp divider 5.
In practice, the divider discs 51 are driven for rotation at a rotation speed about 0.3 to 3 RPM. Any enexpected happening during sizing operation may cause the warps Y to move downwards and be caught by the rotary shaft 53. In order to prevent this trouble, a second barring rod 58 is arranged in parallel to the rotary shaft 53, on the upstream side of the divider discs 51 and at a level below the warp sheets. This second barring rod 58 effectively blocks excessive downward movement of the warps Y travelling through the warp divider 5. As for the location of this second barring rod 58, it may be arranged on the downstream side of the divider discs 51 as shown in FIG. 4.
The driving system 60 for the warp divider 5, in accordance with the present invention, should preferably be separated from that for the sizing machine so the driving system 62 its operation can be controlled independently of the driving of the sizing machine. In practice, the warp divider 5 is driven for movement simultaneously with initiation of running of the sizing machine. When the sizing machine has ceased its running, the warp divider 5 stops its movement with a prescribed time-lag.
Water is advantageously used for the liquid W in the wash bath 56. The water may contain any suitable agent or agents effective for removal of size dregs and fluffs from the divider discs 51.
It was confirmed through practice by the inventor of the present invention that the following advantages are assured by use of the sized warp divider in accordance with the present invention:
(a) Size dregs and fluffs are removed off the discs by the liquid in the wash bath before horizontal dividing of the warps. Consequently, the sized warps always come into contact with clean and smooth side faces of the divider discs, thereby avoiding damages on the warps.
(b) Since the warps contact the clean and moderately wet side faces of the divider discs, fluffs generated by warp dividing are made to lie flatly on the surface of warps, thereby assuring production of high quality sized yarns. This advantage should particularly be appreciated in the case of spun yarns.
(c) Liquid drops in the space between adjacent divider discs are completely removed by pneumatic blow in advance to passage of the warps therethrough. This effectively avoids the danger of uneven size content or drying effects on the warps processed, thereby greatly minimizing yarn breakage during weaving operations and greatly minimizing formation of weaving defects. (d) Use of the barring rods effectively prevents faulty dividing of warps and breakage of warps which are otherwise caused by excessive vertical movement of the warps. This greatly contributes to the running efficiency of sizing machines and the yield of sized warps. (e) Use of the independent driving system for the warp divider enables the divider discs to rotate over a prescribed period even after the sizing machine has stopped running. Due to this continued rotation of the divider discs, size dregs and fluffs adhering to the divider discs can be completely removed before solidification. As a consequence, the faces of the divider discs are kept very clean and smooth at restarting of the sizing machine, thereby avoiding the danger of yarn breakage which otherwise is caused by presence of solidified size dregs and fluffs left on the divider discs. What I claim is:
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A sized warp divider of a rotary divider disc type is provided with a wash bath containing flow of liquid for partial immersion of the discs for removal of size dregs and fluffs, and an air jet ejector for removal of liquid drops remaining in spaces between the discs after the immersion for even sizing and drying effects on warps. Beautifully cleaned faced of the discs assures smooth and ideal contact with the running warps, thereby greatly improving the quality of the product and efficiency of the process.
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This application claims priority from U.S. Provisional Application No. 60/005,985, filed Oct. 27, 1995.
FIELD OF THE INVENTION
The present invention relates to a method for treating plastic polymers to reduce or remove organic contaminants. More particularly, the present invention relates to a method of treating, by continuous means, a flowable polymer mass with a solvating fluid in an environment at which the solvating fluid is in a supercritical state and is subject to conditions sufficient to preferentially solvate and extract organic, and especially non-volatile, contaminants from the polymer mass.
BACKGROUND OF THE INVENTION
The plastics industry has recently begun to focus more attention on the use of recycled plastics in the manufacturing of new plastic materials for both industrial chemical and food-grade applications. This has been in response to the public demand for decreasing the amount of waste that we produce (which can lessen our reliance on landfills and waste-to-energy facilities) and for making more efficient use of our resources (e.g., energy).
The plastics industry has recognized that recycled plastics can serve as an economical substitute for virgin materials. The challenge, however, has been to devise appropriate and economical means of processing recycled plastics for use as substitutes for virgin materials for a wide variety of applications.
Although various methods have been developed for processing of recycled plastics, there remains a need to develop commercially efficient and economical means for processing of recycled plastics for use as substitutes for virgin materials, as are normally required for high purity polymeric materials or food-grade applications. Most presently known processes are inadequate for obtaining high purity recycled plastics, for commercial purposes, because such processes are primarily directed to the reduction or removal of volatile or surface contaminants, or are inappropriate to meet industrial demands for high volume and high efficiency processing.
Accordingly, there remains a need to develop processing techniques that remove both volative and non-volatile organic contaminants which can provide high purity polymeric materials from recycled plastic polymer feedstocks for use as substitutes for virgin materials.
In addition, governmental authorities around the world have begun to promulgate regulations for plastic materials to establish basic guidelines for the use of recycled plastics in food-grade applications. The two primary guidelines are as follows: (1) the packaging will not endanger the consumer through product adulteration by migration of material from the package; and (2) the package will not detract from the taste and smell of the food.
The Food and Drug Administration (FDA), the regulating authority in the United States, has established a threshold of regulation for indirect food additives from plastic packaging as 0.5 ppb dietary intake. This threshold level defines the maximum migration from the plastic into the food that the FDA has determined to be an acceptable risk.
In the processing of plastics, this threshold level may be attained in the end use material by reduction or removal of contaminants to this level, or by mixing an appropriate amount of virgin materials with the recycled materials.
The FDA has also devised a test protocol that may be used to determine whether certain recycled plastics meet its threshold of regulation. The FDA has identified the limits for various plastic polymers in conduction with a series of surrogate chemicals that the FDA has deemed to be representative of the estimated 60,000 chemical in commerce.
These surrogates were chosen to represent the various physical and chemical classes of compounds, and cover the categories of polar volatiles, polar non-volatiles, non-polar non-volatiles, non-polar volatiles, and metallics/organometallics. Polar volatiles include chloroform and 1,1,1-trichloro-ethane; polar non-volatiles include diazinon, tetracosane, and benzophenone; non-polar non-volatiles include lindane, squalane, eicosane, and phenyldecane; non-polar volatiles include gasoline and toluene; and organometallics include disodium monomethyl arsonate, zinc stearate and copper II ethyl hexonate.
FDA testing has also provided the threshold limits for various plastic polymers with respect to these chemicals.
Accordingly, it would advantageous to the industry to develop appropriate means to recycle plastics to such purity levels. Various means are known in the art for removal and extraction of impurities and contaminants.
The removal or extraction of impurities and contaminants from a wide variety of plastic polymers using fluids that are at or near supercritical conditions as an extractant or solvating fluid is well known. Extraction of contaminants with supercritical fluids such as carbon dioxide as compared to organic solvents has advantages of lower cost, ease of operation and most importantly eliminates the disposal problems associated with organic solvent waste. However, the processes as known and practical to date generally suffer from inherent disadvantages in that they are either batch processes using one or more extraction vessels such as autoclaves or are slow and/or relatively inefficient in design. The known processes do not result in efficient removal of unwanted contaminants and do not provide a purified polymer in a form that is easily useable without further processing, i.e., without remelting and repelleting.
U.S. Pat. No. 4,563,308 (assignee Stamicarbon) discloses batch removal of impurities from a ethylene-alkene-diene rubber in an autoclave using a supercritical fluid such as carbon dioxide, nitrogen, oxide, nitrogen dioxide, sulfur dioxide, etc. EP Application No. 233,661 (assignee Stamicarbon) discloses the supercritical extraction of impurities from a molten polymer in an extruder in which the exit die functions as a pressure seal to establish a supercritical pressure in the extruder. The supercritical fluid is mixed with the polymer under high pressure in the barrel of the extruder and the impurities become dissolved in the supercritical fluid. The pressure on the mixture is instantaneously released to atmospheric pressure upon exiting the extruder causing vaporization of the impurity containing supercritical fluid from the polymer. This arrangement results in the inability to maintain adequate control over the pressure in the extruder barrel which causes nonuniform flow of the supercritical fluid. This causes erratic flow of the polymer mass in the extruder and produces a nonuniform polymer product, that may be characterized by a foaming of the polymer product or a “popcorn” effect. In order to provide a commercially saleable product, remelting and pelleting of the extruded polymer is generally required. Further, the efficiency of contaminant removal is relatively low.
U.S. Pat. No. 5,237,048 (assignee Toyo Engineering) discloses the removal of volatile impurities from a molten polymer with a supercritical fluid. A wide variety of polymers and supercritical fluids are disclosed and the extraction is carried out under high pressure in a countercurrent extraction tower.
U.S. Pat. No. 4,902,780 (assignee Rhone-Poulene Sante) discloses removal of residual monomers from a styrenevinylpyridine copolymer with supercritical carbon dioxide in an autoclave.
U.S. Pat. No. 4,703,105 (assignee Dow) describes a method for treating a reaction mixture of styrene polymerized with an equal amount or more of acrylonitrile and containing free styrene and acrylonitrile monomers with supercritical carbon dioxide or sulfur hexafluoride in a series of fluid extractors.
U.S. Pat. Nos. 5,049,647, 4,764,323 and 5,073,203 (assignee CoBarr) disclose methods for purifying polyethylene terephthalate resin by contacting the resin with an atmosphere containing carbon dioxide under supercritical conditions in an autoclave.
U.S. Pat. No. 5,049,32 (assignee Airco) and U.S. Pat. No. 5,133,913 (assignee Toyo Engineering) disclose the use of supercritical fluids to both remove volatile impurities from a variety of plastic polymers and to function as blowing agent for foaming the resulting polymer. U.S. Pat. No. 5,009,746 discloses an extensive bibliography directed to the use of supercritical fluids to extract impurities from a wide variety of substrates.
A process for reducing the acetaldehyde content in polyethylene terephthalate chips is disclosed in U.S. Pat. No. 4,223,128 to Hallick, et al. The process comprises stabilizing the polyethylene terephthalate by heating it at an elevated temperature in air and maintaining an air to chip ratio at a predetermined value of at least about 0.8 standard cubic foot of air per minute/pound of resin per hour and at a vapor velocity of at least about 0.5 foot per second.
U.S. Pat. No. 5,080,845 (assignee Werner & Pfleidere) discloses the removal of impurities from plastic polymers in two serially connected extruders using supercritical carbon dioxide in the first extruder. In the first extruder, the plastic polymer is contacted with an extraction gas at supercritical pressure to dissolve the impurities. The mixture of the plastic polymer and the carbon dioxide is then transferred through a pressure-relief valve to a second extruder. In the second extruder, the reduced pressure instanteously vaporizes the supercritical carbon dioxide containing dissolved impurities, which is vented from the polymer. The polymer is then subjected to vacuum for removal of any residual gases and extruded as granular product. The reduced pressure in the second extruder operates to promote separation of the carbon dioxide from the polymer as a gas, but will not carry off non-volatiles which will be reabsorbed into the molten polymer.
There are two basic types of impurities which occur with respect to polymers in which the method of the present invention has utility. Some virgin plastics, upon polymerization contains a distribution of species having different molecular weights. The low molecular weight components comprising unreacted short chain monomers, diners etc., collectively referred to as oligomers, must be significantly reduced for many end uses of the fully reacted polymer. The removal of low molecular oligomers eliminates problems of noxious hydrocarbon vapor formation during processing and generally improves the handling and workability of the polymer end product. The oligomers are also preferably removed if the polymer is intended for use in food applications, for example as packaging, to avoid permeation or leaching of the oligomers from the packaging material into the food product.
The second type of impurity or contaminant is ordinarily found in refuse plastic which contain impurities resulting from contact with a material during prior usage. In some instances, these impurities may be toxic or hazardous and desirably are removed in order to avoid having to dispose of the refuse in a hazardous material site. In other instances, to which the present invention is particularly directed, plastic materials obtained from ordinary refuse collection may be processed to low impurity levels such that they may replace all or part of the virgin polymer raw material in the manufacture of second generation articles.
The present invention is particularly useful in the removal of unwanted contaminants from high density polyethylene (HDPE). HDPE is a common resin material for blow molded bottles which are used for the storage of milk, detergents, pesticides and motor oil and a significant amount of HDPE is used in consumer product packaging. Polyethylene's properties, particularly HDPE, allow it to be reprocessed, i.e., recycled. A significant concern in recycling polyethylene is the trace levels, i.e., less than 200 ppm, of contaminants inherently associated with the recycle HDPE stock that cannot be removed by conventional washing procedures. In many cases, the contaminant, for example, d-limonene, benzene, toluene, permeates into the plastic through absorption or adsorption. Reprocessing of HDPE by conventional remelting in an extruder may result in the generation of volatile contaminant fumes which may be harmful to the environment and to personnel operating the equipment, and which, if not substantially removed from the reprocessed HDPE, will prevent the recycled HDPE from being used in many applications, for example in containers for foods intended for human consumption
The method of the present invention can be used to remove unwanted contaminants from both virgin polymers and from recycled polymers. As more fully set forth herein, the method is readily practiced in the efficient removal of unwanted contaminants. When used to process polymers collected as refuse, the process can-upgrade in the value of the processed material in the marketplace.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of the method of the invention to remove unwanted contaminants from polymers.
SUMMARY OF THE INVENTION
In its broadest sense, the invention is directed to the continuous removal of one or more undesired contaminants from a molten or substantially molten plastic polymer flowing through a treatment zone in which there is established a treatment environment at which the polymer is substantially molten. A solvating fluid that is supercritical at or near the conditions of the treatment environment and which is a preferential solvent for one or more of the undesired contaminants at the treatment environment conditions is injected into the treatment zone into intimate contact with the molten polymer in the treatment zone thereby causing the undesired contaminants to become dissolved in or otherwise preferentially associated with the supercritical fluid, i.e., by dissolution, absorption, entrainment, etc. The supercritical fluid carrying with it the undesired contaminant or contaminants is thereafter vented or otherwise removed from the treatment zone leaving behind a polymer of improved purity which can be further processed as desired. The purified polymer may be recovered from the treatment zone, degassed and pelleted in a conventional manner. The solvating fluid may include one or more modifier fluids which enhance the solvating ability of the supercritical fluid for certain contaminants as discussed more fully hereinafter.
Preferably the removal of unwanted contaminants is effected in a treatment zone established within the barrel of a twin screw extruder. One example of a twin screw extruder that may be utilized in the practice of the present invention is that sold by American Leistritz, Model No. LSM34GG. The mechanical details of the extruder and its operation do not form a part of this invention except to the extent that the extruder is operated in order to maximize the contact between the polymer mass and the supercritical solvating fluid in order to cause removal of unwanted contaminants. A single screw extruder may be used if desired, and in some instances may be preferred.
It is important to the present invention to create a treatment zone within the barrel of the extruder which is maintained at a particular temperature and pressure, depending upon the polymer being treated, that creates a treatment environment that enhances removal of unwanted contaminants from the polymer mass. The treatment environment is selected to maintain the polymer in a flowable state such that it can be readily transported in and out of the treatment zone, i.e., in an extruder. Preferably, the treatment environment is selected so that the polymer is maintained in a flowable molten state and is of a viscosity such that it can be readily conveyed through the treatment zone by the extruder screw impeller. It is to be understood that there may be isolated bits or pieces of solid or semisolid polymer within the polymer mass, the key being that the polymer be sufficiently flowable that it is transportable through the extruder and can be intimately mixed with the supercritical fluid in order to cause transfer, i.e., dissolution, of the unwanted contaminants into the supercritical fluid phase for subsequent removal from the treatment zone and the extruder.
While it is possible for the treatment zone to comprise substantially the entire extruder barrel with suitable pressure seals or similar mechanical devices at the extruder entrance and exit in order to maintain the treatment conditions within the treatment zone, it has been found to be preferable to have the treatment zone comprise a portion of the extruder barrel upstream of the extruder exit followed by a lower pressure degassing zone (also referred to herein as the “vacuum zone”) downstream of the treatment zone between the treatment zone and the extruder exit. A degassing zone has been found to be desirable in order to insure delivery of a homogeneous molten polymer mass at the extruder exit for further processing and to insure complete removal of residual gases from the polymer mass.
It may also be desirable to treat the polymer in a plurality of treatment zones depending upon the nature of the unwanted contaminants present and the degree of polymer purity desired. The plurality of treatment zones may be contained within a single extruder or in different extruders, as may be desired. The solvating fluid may be introduced into the treatment zones at a single point or at multiple points which may be spaced circumferentially of the extruder barrel as well as axially along the barrel.
Any one of a wide number of materials may be used as the supercritical solvating fluid depending upon the polymer being purified, the contaminants being removed, and the purity being sought in the polymer product. The solvating fluid should be supercritical at or near the treatment environment conditions in order that it will act as a solvating agent for one or more of the unwanted contaminants present in the polymer raw material. Generally, the supercritical solvating fluid is a known supercritical fluid which exhibits supercritical properties at treatment environment conditions that are sufficiently mild that the polymer being treated does not become degraded. Examples of supercritical solvating fluids that may be used in the disclosed process include carbon dioxide, carbon monoxide, sulfur dioxide, nitrogen dioxide, nitrous oxide, methane, ethane, propane, steam, ethylene and propylene and mixtures thereof. A preferred fluid for reasons of economy, lack of toxicity and desirable supercritical thresholds is carbon dioxide which has a critical temperature of 31° C. and a critical pressure of 73 bar. Supercritical carbon dioxide also has the desirable effect of lowering the intrinsic viscosity of most molten polymers, and particularly HDPE, at the treatment conditions which enhances the contact between the supercritical carbon dioxide and the polymer mass which increases the efficiency of contaminant separation. Other fluids having desirable solvating properties and supercritical thresholds are considered to be within the skill of the art.
As indicated, it is contemplated to include one or more modifiers in the solvating fluid which enhance the solvating properties of the supercritical solvating fluid for the unwanted contaminants. The use of such modifiers is well known, examples being methanol and isopropanol to enhance the removal of polystyrene oligomers and polynuclear aromatic hydrocarbons. The identification of a wider variety of modifiers that may be used with supercritical carbon dioxide as well as other supercritical fluids is set forth in Supercritical Fluid Technology, A.C.S. Symposium Series 488, Am. Chem. Soc., 1992, pp. 336-361.
The present invention may be employed to purify a wide variety of polymers, and particularly those that are molten at temperatures and pressures that may be conveniently established in an extruder operating environment, at temperatures within the range of between about 150° C. and about 400° C. Examples of polymers suitable for purification in accordance with the present invention include polyolefins, polyesters, polyamides, polyacrylonitrile, and polystyrene, and more specifically polyethylene, polypropylene, polyethylene terephthalate and nylon. As stated, the disclosed process is particularly suited to recover purified HDPE from recycle scrap. Other recycled polymers that may be purified as described herein will be apparent to those skilled in the art.
The method of the invention provides a highly efficient continuous process to efficiently remove unwanted contaminants from polymers. The principal contaminants that are conveniently removed by the disclosed process are low molecular weight oligomers that are present in the reaction mixture resulting from the polymerization reaction. The present invention contemplates removal of such unwanted contaminants as a purification step in the overall polymer production process or as a subsequent processing step performed on the virgin polymer prior to use of the polymer in subsequent processing or fabrication operations.
The present invention has also been found to be of significant commercial value in the processing of recycled polymer articles that, due to their environment during usage, for example as a container, have become contaminated with one or more materials that may interfere with their ability to be reformulated and reused. One example of a contaminated container that may be processed in accordance with the disclosed invention are containers used for storing and transporting toxic chemicals such as solvents, etc. which have heretofore not been able to be recycled into certain uses such as food containers due to the inability to remove residual toxic contaminants to the low levels mandated for food uses. Other examples of contaminated plastic containers include pesticide containers, motor oil containers and milk cartons.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, there is schematically illustrated an extruder 10 having an inlet 12 and an exit 14 . The polymer to be purified, for example HDPE in particulate powder or chip form, is delivered from a hopper 16 into a suitable premelt extruder 18 where it is melted into a molten mass and delivered to the inlet of extruder 10 . First and second spaced apart pressure seals 20 and 22 are disposed within the barrel of extruder 10 defining therebetween a treatment zone 24 which is maintained at a desired temperature and pressure defining supercritical treatment conditions for the solvating fluid at which the HDPE is a flowable molten mass. When the solvating fluid is carbon dioxide and the polymer mass is HDPE, the treatment conditions may be between about 180 20 C. and about 250° C. and between about 80 bar and about 200 bar.
One or more inlets 26 are provided for injecting of a carbon dioxide solvating fluid. The solvating fluid inlets 26 may be spaced along the barrel of the extruder, and may be arranged so that the solvating fluid is introduced circumferentially of the barrel as well as at spaced longitudinal points as may be desired.
As shown in FIG. 1, liquefied carbon dioxide is withdrawn from a suitable vessel 28 and pumped by pump 30 to injection inlets 26 . Control valve 32 controls the flow rate of the carbon dioxide entering the treatment zone 24 via inlets 26 when it intimately contacts and mixes with the molten HDPE flowing through treatment zone 24 , the unwanted contaminants becoming dissolved or otherwise associated with the supercritical carbon dioxide.
The supercritical carbon dioxide containing dissolved unwanted contaminants is withdrawn from the treatment zone 24 via any suitable venting arrangement 34 which seals the extruder against pressure leakage as is well known in the prior art. The extruder includes a mixing zone 36 downstream of the treatment zone 24 which is vented to the atmosphere or a suitable collection device, not shown, via vacuum vent 38 maintained at a vacuum of between about −500 and about −900 mbar gauge in order to remove any remaining solvating fluid, i.e., carbon dioxide and associated contaminants, from the polymer and to reduce the pressure on the polymer mass essentially to atmospheric pressure to permit convenient extrusion of the purified polymer from the extruder without excessive blowing or out gassing that might occur if the polymer was extruded directly from the high pressure conditions within the treatment zone to the ambient surroundings. The carbon dioxide exiting the treatment zone 24 via vent 34 is preferably at a pressure of from about 80 to about 200 bar and a temperature of from about 80° C. to about 120° C. The carbon dioxide to polymer ratio in the treatment zone is preferably in the range of from about 0.2:1.0 to about 5:1. The polymer preferably has a residence time in the treatment zone of from about 2 to about 20 minutes.
The following experiments were conducted in order to demonstrate the improved efficiency of continuous removal of impurities from recycle HDPE with supercritical carbon dioxide in a single treatment zone extruder. The extruder was an American Leistritz twin screw extruder of the type schematically illustrated in FIG. 1 . The extruder had a diameter of 34 mm and had 12 heating zones. The treatment zone was 660 mm in length and the degassing zone was 400 mm in length. Temperature within the treatment zone was controlled in the range of 180-200° C. Molten plastic was fed into the twin screw extruder from a 2.54 cm single screw premelt extruder. The mass flow rate of plastic fed to the twin screw extruder was 4-5 kgs/hr with a screw speed in the range of 100-200 rpm.
The HDPE plastic raw material was obtained from curb side collection of high density polyethylene bottles used to contain detergents, fabric softeners, shampoos and other industrial cleaning materials. The bottles were triple rinsed with water and dried before grinding. For control experiments, naphthalene flakes were premixed with virgin HDPE powder obtained from Solvay under the tradename B-54-25-H by thoroughly shaking and tumbling.
Carbon dioxide was used as the supercritical solvating fluid for the experiments, although nitrogen was also used to check the solubility versus sweeping effect of the supercritical fluid. Liquid carbon dioxide at room temperature was drawn from a cylinder having a dip tube and a Haskel pump was used to pressurize the carbon dioxide of 100 to 200 atm. A pressure probe was used to measure the pressure inside the treatment zone. The flow rate of supercritical carbon dioxide was measured using a turbine flow-meter before it was injected into the treatment zone. To prevent high pressure carbon dioxide from exiting at the die and foaming the plastic, and to maintain a supercritical pressure inside the treatment zone, a set of melt seals were used. These dynamic seals were formed by using either a reverse flight element or a shearing disk. Supercritical carbon dioxide containing dissolved contaminants were removed before the second melt seal via a vent-stuffer device with a throttle valve. The vent-stuffer device created a pressure seal effectively preventing escape of the molten plastic from the extruder while permitting releasing of the carbon dioxide through the throttle valve. This throttle valve was also used to adjust the carbon dioxide flow rate and the pressure in the treatment zone. The temperature of the carbon dioxide exiting the treatment zone was in the range of 80-120° C. A vacuum pump adjacent the exit end of the extruder was used to remove any residual carbon dioxide and/or contaminant fumes. The purified plastic polymer free from contaminants was extruded from the extruder exit and cooled in a water bath, after which it was pelletized and stored in glass jars for analysis.
Analysis of each plastic sample for contaminants was performed using a Hewlett Packard 5890 Series II GC/MS. Before analysis, plastic samples were extracted for 16 hours using an automated Soxhlet 2000 Extractor at 150° C. with methylene chloride as the solvent. Each sample was analyzed three times, and a mean was reported.
EXAMPLE I
This experiment was carried out in the described intermeshing counter-rotating twin screw extruder operating at a screw speed of 100 rpm. The raw material feedstock was recycled HDPE obtained from curbside refuse collection ground into chips of approximately 0.5 inch×0.25 inch. The chips were fed via a feed hopper into a premelter maintained at a temperature of about 200° C. to provide a molten feed into the extruder.
A control sample of the contaminated recycle stock was processed through the extruder at a rate of 2.7 Kg/hr. without introduction of any solvating fluid in the treatment zone which was maintained at a temperature of 200° C. A vacuum of −700 mbar gauge was drawn on the degassing zone adjacent the extruder exit.
A second sample of the identical raw material was then processed using supercritical carbon dioxide as the solvating fluid. Carbon dioxide at a pressure of 100 atm and temperature of 20° C. was introduced at a flow rate of 3.0 Kg/hr. into the treatment zone which was at a temperature of 200° C. A carbon dioxide contaminant containing stream was vented from the treatment zone at a pressure of 100 bar. The residence time of the molten polymer in the treatment zone was 3.5 minutes.
Samples of the control and extracted samples were extracted with methylene chloride for 16 hours and were analyzed as set forth above. The results obtained were as follows:
Control
Treated
%
Identified Contaminants
(ppm)
(ppm)
Removed
Camphene
6.64
N.D.*
>99
d-Limonene
19.04
2.34
87.7
Benzene, 1-methyl-4-
7.90
N.D.
>99
(1-methylethyl)
Dodecane
6.51
N.D.
>99
Tetradecane
16.75
4.37
73.91
1-Tetradecane
8.24
N.D.
>99
4-tert-Butylcyclohexyl acetate
6.36
N.D.
99
1-Hexadecane
7.58
2.62
65.49
Total
79.02
9.33
88.20
EXAMPLE II
Samples of recycled HDPE bottles obtained from quantum recycling were processed under conditions as in the preceding example and the following results were obtained:
TABLE 2
Control
Treated
%
Identified Contaminants
(ppm)
(ppm)
Removed
Carene
12.86
2.69
79.08
d-Limonene
94.84
9.74
89.73
Dodecane
14.65
N.D.
>99
Tridecane
12.27
N.D.
>99
Tetradecane
27.56
5.38
80.47
Tetradecane
23.35
4.40
81.15
Pentadecane
11.92
3.03
74.59
Hexadecane
23.32
6.63
71.56
Hexadecane
14.03
5.77
58.86
Dodecanoic Acid
17.80
6.69
61.82
Octadecane
17.20
9.38
45.50
Cyclotetradecane
60.44
38.46
36.37
Nonadecane
46.39
29.29
36.86
Hexadecanoic Acid
20.84
10.46
48.93
Tetraconsane
17.42
13.51
22.47
Phosphoric Acid
25.01
21.71
13.19
Docosene
22.01
18.08
17.19
Total
461.92
185.5
59.84
EXAMPLE III
The relative effectiveness of carbon dioxide and nitrogen as the solvating fluid was compared by treating virgin high density polyethylene powder contaminated with approximately 0.5 percent by weight naphthalene (m.p. 80-820° C.) in an extruder of the type described in the above examples above. The treatment conditions were as follows:
Source
Virgin HDPE + Naphthalene
(m.p.: 80-82° C.)
Type of Material
HDPE Powder, melt index − .40
(2160 gm/190° C.)
CO 2 Temperature
20° C.
CO 2 Pressure
200 atm
N 2 Pressure
200 atm
N 2 Temperature
20° C.
Flow Rate of CO 2
3.6 kg/hr
Flow Rate of N 2
3.6 kg/hr
Temperature of treat-
210-220° C.
ment & mixing zones
Vacuum
−700 mbar
Screw speed
120 rpm
The resulting polymer was extracted with methylene chloride and analyzed as described to determine the amount of naphthalene removed. As seen in the following table, carbon dioxide was superior to nitrogen in removing naphthalene under the operating conditions of the experiment.
TABLE 3
Control % by
Treated % by
%
Fluid
weight
weight
Removed
CO 2
0.56
0.035
93.75
N 2
0.52
0.22
57.70
EXAMPLE IV
These experiments were performed on polyethylene terephthalate (PET). Source of recycled PET flakes was two liter post industrial bottles. These bottles were ground into chips (flakes) of approximate size 0.3 ″×0.2″. These chips were contaminated purposely with lindane and toulene as follows:
A mixture of lindane and toulene was prepared with 90% toulene and 10% lindane.
This mixture was thoroughly mixed with PET flake and stored for two weeks at 40° C. with periodic agitation.
Contaminant was drained and PET flake was put through a commercial washing process.
After washing, the contaminated flake was blended with curbside recycled PET, one part contaminated flake and 2 parts curbside recycled PET flake.
PET is a hygroscopic material and it absorbs moisture easily. Before PET was processed, it was dried in a Novatech drier at a temperature of 310° F. Dry PET was fed to the extruder where it was cleaned using supercritical carbon dioxide. Treated PET was collected and analyzed using a Soxhlet extraction method.
Extraction experiments were performed twice, only difference between the two being the amount of time the contaminated PET was dried before subjecting to extraction process.
Results:
Extraction efficiency for toulene and lindane is shown in Table 1.
TABLE 4
Lindane
Toluene
Sample ID
Description
(ppm)
(ppm)
1.
Initial Blend
150
8680
2.
Control 1: (Dryer-4.5 hr
88.9
1850
@ 310° F.)
3.
Treated 1: (1200 psi CO 2 /
10.2
21.2
vacuum
Percentage Removed
88.5
98.9
4.
Control 2: (Material held
54
475
in dryer for 48 hr at
reduced temp.)
5.
Treated 2: (1200 psi CO 2 /
5.6
15.7
vacuum
Percentage Removed
89.6
96.7
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The present invention relates to a method for treating plastic polymers to reduce or remove organic contaminants. More particularly, the present invention relates to a method of treating, by continuous means, a flowable polymer mass with a solvating fluid in an environment at which the solvating fluid is in a supercritical state and is subject to conditions sufficient to preferentially solvate and extract organic, and especially non-volatile, contaminants from the polymer mass.
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CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation of U.S. utility application entitled, “Method of Manufacturing an Environmentally Resilient Structural Panel,” having Ser. No. 12/536,275, now U.S. Pat. No. 8,141,221 B2 filed Aug. 5, 2009, which is a divisional application of U.S. utility application entitled, “Environmentally Resilient Corrugated Building Products and Methods of Manufacture,” having Ser. No. 11/035,548, filed Jan. 13, 2005, which is allowed, and which are entirely incorporated herein by reference.
TECHNICAL FIELD
The present disclosure is generally related to building products and, more particularly, is related to products and manufacturing methods for environmentally resilient building products.
BACKGROUND
Many different products have utilized, and continue to utilize, sheet metal as a raw material for constructing various components. Sheet metal generally possesses a high tensile strength, but is often very flexible. For structural purposes, the flexibility can be reduced through the use of additional structure attached to the sheet metal, such as beams, purlins, bars, and posts, among others. Additional structural components, however, increase the cost for the additional materials and increase the size and weight of the assembled component.
One method for avoiding the requirement for additional structure is to break or bend the sheet along a line where the reduction in flexibility is desired. When done as a series of parallel bends to form channels or ridges, this is known as corrugating. Corrugating is known to produce metal sheet products with significantly reduced flexibility along at least one axis. Although the corrugation may be produced by performing a series of independent breaks on a metal sheet, corrugating machines also referred to as roll forming machines have been developed to provide corrugation to flat sheet metal in a continuous process. An example of the prior art relating to roll forming machines can be found in U.S. Pat. No. 4,269,055, which is hereby incorporated by reference in its entirety.
Metal sheets are often used in applications where specific aesthetic properties are desirable on at least one surface of the metal sheet. In some cases, the aesthetic property may constitute a specific color. Methods for applying a solid color to corrugated metallic products have previously been performed using spraying or coating processes 100 , as illustrated in FIG. 1 . Referring to FIG. 1 , the flat metallic product 110 is unrolled from a coil 102 and made proximate to, for example, spray nozzles 120 , which deliver a sprayed paint or coating 130 to the surface of the flat metallic product 110 . After coating or painting, the flat metallic product is dried or cured using, for example, a heater or oven 140 and then rolled into a coil 104 . Other cases may require specific graphical images or patterns in lieu of a solid color. Some methods of applying a graphical image or pattern to flat metallic product include immersion graphics methods where, for example, an inked film is applied to the flat metallic product, which is then immersed to dissolve the film, leaving the ink image or pattern on the flat metallic product. Like the painted coating products discussed above, the immersion graphics products may not provide a surface that is sufficiently resistant to scratching, abrasion, weathering, or fading due to outdoor exposure or mechanical impact associated with subsequent processing, assembly, or use.
One technique for providing mechanically resilient protection for metallic sheet products includes laminating. The laminating process 200 in this context, as illustrated in FIG. 2 , includes adhesively bonding a graphic film 202 to at least one surface of a flat metallic sheet 201 . By way of example, the graphic film 202 may be applied using the pressure of a laminating roll 220 . Additionally, the laminating roll 220 may possess specific surface properties which are transferred or embossed into the surface of the graphic film 202 during application. The resulting laminated metallic sheet 210 includes a graphic film 202 , which may possess specific aesthetic properties including solid colors, metallic finishes, patterns, and graphical images. Additionally, if embossing was performed, the graphic film 202 may possess specific surface finish properties such as brushed, matte, or pebbled, among others. This process, however, has only been applicable to flat products because the manufacturing impracticality of continuously processing laminated corrugated products. For example, previous attempts to corrugate a laminated sheet have resulted in a graphic film that weakens and cracks during subsequent processing and is not resistant to damaging elements associated with an outdoor environment.
Thus, a heretofore-unaddressed need exists in the industry to address the aforementioned deficiencies and inadequacies.
SUMMARY
Embodiments of the present disclosure provide an environmentally resilient structural product, comprising: a vinyl laminate and a formed-sheet metallic substrate having a first side; wherein the vinyl laminate is adhesively attached to the first side.
Briefly described, other embodiments of the present disclosure provide an environmentally resilient outdoor building, comprising: at least one formed-sheet metallic panel, the panel comprising a vinyl layer, and a corrugated metallic substrate having a first side, wherein the vinyl layer is bonded to the first side.
Embodiments of the present disclosure can also be viewed as methods for providing a decorative, environmentally resilient, structurally significant panel. In this regard, one embodiment of such a method, among others, can be broadly summarized by the following steps: bonding a first side of a vinyl layer to a first side of a flat metallic sheet; and deforming the flat metallic sheet to create a plurality of parallel ribs in the first side of the metallic sheet.
Other systems, methods, features, and advantages of the present disclosure will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Many aspects of the disclosure 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 present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
FIG. 1 is a side view of a coating/painting process for metal products as is known in the prior art.
FIG. 2 is a side view of a process of applying a laminate to flat metallic sheet as is known in the prior art.
FIG. 3 is an illustration of a side-elevational view of an exemplary roll former used in an embodiment, as disclosed herein.
FIG. 4 is an illustration of a partial top view of the exemplary roll former of FIG. 3 used in an embodiment, as disclosed herein.
FIG. 5 is an illustration of a partial end view of a set of complementary rollers and a partial cross-sectional view of a vinyl laminated metallic sheet of the exemplary roll former of FIG. 3 used in an embodiment, as disclosed herein.
FIG. 6 is a side cross-sectional view of a flat metallic sheet with a vinyl laminate.
FIG. 7 is an end cross-sectional view of a vinyl-laminated corrugated metal sheet, as disclosed herein.
FIG. 8 is an illustration of side-elevational view of an exemplary roll former used in an embodiment, as disclosed herein.
FIGS. 9A-9D are end cross-sectional views of exemplary formed-sheet vinyl laminated metallic products, as disclosed herein.
FIG. 10 is a block diagram of an exemplary method of producing environmentally resilient products as disclosed herein.
FIG. 11 is a perspective view of an exemplary building constructed using environmentally resilient corrugated metallic products, as disclosed herein.
DETAILED DESCRIPTION
Reference is now made in detail to the description of the embodiments as illustrated in the drawings. While several embodiments are described in connection with these drawings, there is no intent to limit the invention to the embodiment or embodiments disclosed herein. On the contrary, the intent is to cover all alternatives, modifications, and equivalents.
Reference is made to FIG. 3 , which illustrates a side-elevational view of an exemplary roll former used in an embodiment, as disclosed herein. The roll former 300 begins with a vinyl laminated flat metallic sheet 305 , as manufactured in a device consistent with the prior art, as discussed in reference to FIG. 2 addressed in the preceding Background section. The vinyl laminated flat metallic sheet 305 of FIG. 3 retains a carrier film (not shown) associated with the vinyl laminating material. The vinyl laminated flat metallic sheet 305 is propelled in direction A and drawn between a first set of complementary forming rollers 322 and 323 to form a first set of channels/ridges, creating a partially formed sheet 306 . The partially formed sheet 306 is propelled from the first set of complementary forming rollers 322 and 323 and drawn between a second set of complementary rollers 324 and 325 . The second complementary forming rollers 324 and 325 form additional channels/ridges to create partially formed sheet 307 . Similarly, the partially formed sheet 307 proceeds through complementary forming rollers 326 and 327 to form a final set of channels/ridges such that the corrugated sheet 308 is created. The corrugated vinyl laminated metallic sheet 308 is then fed into a shear 340 , where the continuous sheet is cut into panels for subsequent packaging or manufacturing (not shown).
Reference is now made to FIG. 4 , which illustrates a partial top view of the exemplary forming roller table of FIG. 3 , as discussed above. The vinyl laminated flat metallic sheet 305 is propelled in a direction A between a first top forming roller 322 and a first bottom forming roller, which is not visible in this view. The partially formed sheet 306 produced by the first complementary forming rollers 322 and 323 (see FIG. 3 ) has channels/ridges 316 corresponding to the profile of the gap between the first forming rollers 322 and 323 (see FIG. 3 ). The partially formed sheet 306 is then drawn into the gap between a second top forming roller 324 and a second bottom forming roller, which is not visible in this view. The partially formed sheet 307 produced by the first and second complementary forming rollers 322 , 323 (see FIG. 3 ), 324 , and 325 (see FIG. 3 ) has channels/ridges 317 corresponding to the cumulative profile of the gaps between the two sets of complementary forming rollers 322 , 323 , 324 , and 325 .
The partially formed sheet 307 is similarly drawn between a third top forming roller 326 and a complementary third bottom forming roller, which is not visible in this view. A final set of channels/ridges 318 is formed resulting in a corrugated vinyl laminated metallic sheet 308 . Note that as the vinyl laminated metallic sheet progresses through each of the sets of complementary forming rollers, the width of the sheet is reduced by the portion of the sheet profile which is deformed to create the depth and height of the channels/ridges, respectively. In other words, the final corrugated vinyl laminated metallic sheet 308 is not as wide as the vinyl laminated flat metallic sheet 305 that entered the forming roller table 320 . One of ordinary skill in the art knows, or will know, that the complementary forming roller configurations of FIGS. 3 and 4 are merely exemplary and that a roll former 300 configured with any number, combination, or configuration of forming rollers is consistent with this disclosure. For example, an alternative roll former 300 may have four or more complementary sets of forming rollers, each configured to produce a single channel or ridge in a vinyl laminated metallic sheet.
Reference is briefly made to FIG. 5 , which is an illustration of a partial end view of a set of complementary rollers with a partial cross-sectional view of a vinyl laminated metallic sheet. As discussed above, the top forming roller 322 has a complementary profile with the bottom-forming roller 323 . As the vinyl laminated metallic sheet 306 is drawn through the gap between the two forming rollers 322 and 323 , the channel/ridge 316 is formed. One of ordinary skill in the art knows or will know that the multiple channels/ridges 316 may be formed by multiple serially arranged forming roller sets configured at specific widths across the vinyl laminated metallic sheet and that the multiple channels/ridges may aggregate to form a corrugated sheet. Further, one of ordinary skill in the art will appreciate that the channels/ridges may have different depths, widths, and shape profiles.
Further, one of ordinary skill in the art will appreciate that a roll former is but one way to produce formed-sheet products. For example, in addition to roll forming, sheets can be formed using bends, breaks, or folds for introducing the additional dimensional characteristics associated with formed-sheet products. Additionally, one of ordinary skill in the art knows or will know that a formed-sheet product includes any sheet product subsequently processed to introduced additional dimensional characteristics including products with any number, configuration, or combination of bends, breaks, folds, curls, or rolls.
Reference is now made to FIGS. 6 and 7 , which illustrate cross-sectional end views of a vinyl laminated flat metallic sheet and a vinyl-laminated corrugated metal sheet, respectively. The vinyl laminated flat metallic sheet 600 is formed by a laminating process, such as the process disclosed in the above discussion of FIG. 2 , and includes a vinyl laminate 602 , which has a thickness of at least 0.0005 inches, bonded to at least one side of the flat metallic sheet 601 , which has an exemplary thickness ranging from 10 gauge to 35 gauge. The corrugated vinyl laminated metallic sheet 700 of FIG. 7 includes the corrugated metallic substrate 701 and a vinyl layer 702 bonded to at least one side of the corrugated metallic substrate 701 . Additionally, the corrugated vinyl laminated metallic sheet 700 includes multiple parallel channels 710 and ridges 720 .
The metallic sheets or substrates as disclosed herein may be steel, aluminum, tin, copper, or brass, among others.
The bonding of the vinyl layer 602 to the metallic sheet 601 is performed on a flat metallic sheet, as previously discussed in reference to FIG. 2 . The vinyl laminated flat metallic sheet may be processed using the methods herein to produce the corrugated vinyl laminated metallic sheet. Although the corrugated profile of the product 700 is illustrated as including three primary ribs 720 per section with two secondary ribs 710 between each of the primary ribs 720 , one of ordinary skill in the art knows or will know that the methods herein may be utilized to produce numerous combinations of ribs having various and varied geometric profiles and dimensional characteristics. The product 700 also includes a vinyl layer 702 bonded to one side of the metallic sheet 701 . The vinyl layer 702 , which has a thickness of at least 0.0005 inches, is UV-stabilized and provides an ultra-violet light resistant protective covering for the metallic sheet 701 . Additionally, the product 700 provides a vinyl layer 702 that is resistant to delamination. The vinyl layer 702 also provides a decorative finish for the product 700 . For example, the vinyl layer 702 may have solid color or some graphical representation. Exemplary graphical representations include, but are not limited to, metallic finishes such as gold or silver including different textures such as brushed, matte, pebbled, or gloss, among others. Other exemplary graphical representations include, but are not limited to, natural finishes such as wood grain or an outdoor environment blending pattern such as, for example, one sold under the registered trademark, REALTREE®.
Reference is now made to FIG. 8 , which illustrates a side-elevational view of an exemplary roll former used in an embodiment, as disclosed herein. The roll former 800 begins with a vinyl laminated flat metallic sheet 805 , as manufactured in a device consistent with the prior art, as previously discussed in reference to FIG. 2 . The vinyl layer 815 of the vinyl laminated flat metallic sheet 805 includes a carrier film 832 , that may be removed from the vinyl laminated flat metallic sheet 805 or it may be left in place during the forming operation. If the carrier film 832 is removed before the vinyl laminated flat metallic sheet 805 enters the forming roller table 820 , the carrier film is wound onto a separate roll 830 . Although, as illustrated, only one side of the vinyl laminated flat metallic sheet is shown as having a vinyl laminate, one of ordinary skill in the art will appreciate that both sides of the vinyl laminated flat metallic sheet may have a vinyl laminate applied. In an embodiment having two sides of vinyl laminate, the removal of a second carrier film may be performed prior to the roll forming process or the second carrier film may remain attached during subsequent processing.
After removing the carrier film 832 , the vinyl laminated flat metallic sheet 806 is drawn between a first set of complementary forming rollers 822 and 823 to form a first set of channels/ridges, creating a partially formed sheet 806 . The partially formed sheet 806 is propelled from the first set of complementary forming rollers 822 and 823 and drawn between a second set of complementary rollers 824 and 825 . The second set of complementary forming rollers 824 and 825 forms additional channels/ridges to create partially formed sheet 807 . Similarly, the partially formed sheet 807 proceeds through complementary forming rollers 826 and 827 to form another set of ridges/channels such that the corrugated sheet 808 is produced without the carrier film 832 . One of ordinary skill in the art knows or will know that the roll forming process may be performed by four or more sets of forming rollers, each configured to generate an element of the overall profile. The corrugated vinyl laminated metallic sheet 808 may then be fed into a shear 840 , where the continuous sheet is cut into panels for subsequent packaging or manufacturing (not shown). Additionally, excess vinyl laminate may be trimmed at one or more of numerous different stages of the manufacturing. For example, the vinyl laminate may be trimmed before or after the roll forming 820 or before, after, or during the shear function 840 .
Reference is now made to FIGS. 9A-9D , which illustrate end cross-sectional views of exemplary formed-sheet vinyl laminated metallic products, as disclosed herein. The exemplary profile of FIG. 9A includes five primary ribs 902 , each separated by two wide, shallow ribs 904 . The exemplary profile of FIG. 19B similarly includes four primary ribs 912 , each separated by two wide, shallow ribs 914 . As is shown, the primary ribs 912 of FIG. 9B illustrate a different geometrical and dimensional profile than the primary ribs 902 of FIG. 9A . The exemplary profile of FIG. 9C similarly includes four primary channels 922 , each separated by two wide, shallow channels 924 . The exemplary profile illustrated in FIG. 9D includes four wide, shallow channels 932 , one standing seam locking surface 934 , and one standing seam locking tab 936 .
Reference is now made to FIG. 10 , which is a block diagram of an exemplary method of producing environmentally resilient products, as disclosed herein. The method 1000 first bonds a vinyl layer to a flat metallic sheet in step 1010 . Next, optional step 1020 constitutes removing the carrier film component of the vinyl layer. The vinyl laminated flat metallic sheet is deformed using, for example, a roll forming device, to produce channels/ridges in block 1030 . In block 1040 the excess vinyl material is trimmed from the edges of the metallic sheet, if present. This step may be optionally performed before or after the deforming step.
Reference is now made to FIG. 11 , which illustrates a perspective view of an exemplary building constructed using environmentally resilient corrugated products, as disclosed herein. The building 1100 may be fully or partially constructed utilizing corrugated vinyl laminated metallic wall panels 1110 consistent with the disclosure herein. Corrugated vinyl laminated metallic wall panels 1110 may be produced from metallic substrate in the exemplary thickness range from 18 gauge to 30 gauge. As discussed above, the vinyl laminated panels are environmentally resilient. Additionally, or in the alternative, the building 1100 may also utilize one or more corrugated vinyl laminated metallic roof panels 1120 for all or part of the roof. Corrugated vinyl laminated metallic roof panels 1120 may be produced from metallic substrate in the exemplary thickness range from 18 gauge to 30 gauge.
It should be emphasized that the above-described embodiments of the present disclosure, particularly, any illustrated embodiments, are merely possible examples of implementations, merely to provide a clear understanding of the principles of the disclosure. Many variations and modifications may be made to the above-described embodiment(s) of the disclosure without departing substantially from the spirit and principles of the disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and the present disclosure and protected by the following claims.
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An environmentally resilient building product of a vinyl laminated formed-sheet metallic substrate wherein the vinyl laminate is adhesively attached to the formed-sheet metallic substrate to provide a durable and attractive surface. Possible decorative and resilient surfaces include, but are not limited to solid colors, metallic finishes, and graphical images or patterns, all available in a variety of textures.
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RELATED APPLICATIONS
[0001] This application claims priority to Taiwanese Application Serial Number 105112476, filed Apr. 21, 2016, which is herein incorporated by reference.
BACKGROUND
Field of Disclosure
[0002] The present disclosure relates to a down-proof fabric, especially relating to a down-proof knitted fabric.
Description of Related Art
[0003] Down jackets against cold weather are increasingly demanded these years. Since the jackets must be filled with great amounts of down, and a down layer made of the down exhibits no structural strength, each of both sides of the down layer respectively requires a fabric for coverage. Moreover, the down is so fine that it may penetrate through the fabric and thus reduce the mass of down in the down layer. The result is that the efficiency of heat preservation of the down layer is deteriorated.
[0004] To prevent the down from penetrating through the fabric, conventional down-proof techniques mainly involves the adoption of a woven fabric as a down-proof fabric, such as a high-density down-proof fabric woven by finer yarns. However, after several times of washing, the fabric structure becomes loose and reduces the down-proof efficiency. Thereafter, techniques of high-density down-proof fabrics woven by ultra-fine fibers have been developed (e.g., Taiwan Patent No. 1222473). Nonetheless, the ultra-fine fibers tend to disconnect easily during the manufacturing process due to the low Denier number, so as to lower the weaving rate with an unsatisfactory yield rate. In addition, a method of calendaring is suggested to make fabrics dense and reduce the voids between fibers (e.g., U.S. Pat. No. 8,220,499), or a method of heating is suggested to merge the surfaced fibers of fabrics to reduce the voids on the surface of the fabric to prevent the penetration of the down. Furthermore, a surface of the fabric is suggested to be coated with a down-proof film (such as a polysiloxane resin film) in order to achieve the down-proof efficiency. However, the fabric made by this method exhibits poor air permeability, hard hand feeling, and inflexibility due to the thick coating film (normally having a thickness of 30 μm). Also, the additional coating film is unsuitable for the fabrics featuring lightness and thinness.
[0005] To improve hand feeling, the low-density fabric as the outermost-layer fabric is adopted, while a layer of down-proof liner has to be added to achieve the down-proof efficiency. Nonetheless, the down-proof liner affects softness of the entire fabrics, adds extra weight, and is apt to be worn-out and pilling after washing, thus losing the down-proof efficiency.
[0006] The foregoing known down-proof methods show undesired down-proof efficiency on woven fabrics, not to mention when it is to be used on knitted fabrics. This is because the yarn density of the knitted fabrics is lower than that of the woven fabrics, so that the voids between yarns of the knitted fabrics are larger. Even if the knitted fabric is knitted as higher density, the down is still inclined to penetrate and leak out of the fabric. In the end the knitted fabric remains not well washable. In this regard, the down-proof knitted fabrics are barely seen in the market.
[0007] On the other hand, the knitted fabrics exhibit superior flexibility over woven fabrics. A person in clothes made of knitted fabrics feels more comfortable when stretching or exercising. Accordingly, if the knitted fabric is applicable to the down jackets for sports, such as for mountain climbing, the exhibited performance will be incomparable and irreplaceable by the regular woven fabrics. Given the above, it is essential to develop a down-proof technique that can be applied to knitted fabrics.
SUMMARY
[0008] On account that the woven fabrics manufactured by foregoing down-proof techniques are limited to technical drawbacks including poor air permeability and bad hand feeling, the present disclosure aims to provide a down-proof fabric to improve the aforementioned, known disadvantages.
[0009] Hence, the present disclosure provides a down-proof fabric, which includes a base fabric, an adhesive layer disposed on the base fabric, and at least one down-proof functional layer disposed on the adhesive layer. The down-proof functional layer includes a plurality of voids, and a static friction coefficient of an exposed surface of the voids is in a range of preferably 0.39 to 1 so as to block the penetration of the down.
[0010] The present disclosure adopts an ultra-thin film as the down-proof functional layer, which can be embedded on a surface of the base fabric. The characteristic of thinness enables the base fabric to maintain fine flexibility and hand feeling, and the interior has a plurality of voids to facilitate air permeation via the voids and through the down-proof functional layer, thus improving the disadvantage of poor air permeability.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present disclosure can be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawings as follows:
[0012] FIG. 1 illustrates a lateral view of a three-dimensional profile of a down-proof fabric in accordance with the present disclosure.
[0013] FIG. 2A to 2D illustrate cross sectional views of manufacturing a down-proof fabric in respective stages in accordance with the present disclosure.
[0014] FIG. 3 illustrates a cross sectional view of forming a down-proof fabric in accordance with some embodiments of the present disclosure.
DETAILED DESCRIPTION
[0015] Reference will now be made in detail to the present embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
[0016] The singular forms “a,” “an” and “the” used herein include plural referents unless the context clearly dictates otherwise. Therefore, reference to, for example, a gate stack includes embodiments having two or more such gate stacks, unless the context clearly indicates otherwise. Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Therefore, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Further, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. It should be appreciated that the following figures are not drawn to scale; rather, these figures are intended for illustration.
[0017] Referring to FIG. 1 , which illustrates a down-proof fabric 50 in accordance with the present disclosure, which includes a base fabric 10 , an adhesive layer 20 disposed on the base fabric 10 , and at least one down-proof functional layer 30 disposed on the adhesive layer 20 . The down-proof functional layer 30 includes a plurality of voids 32 .
[0018] The base fabric 10 applied in the present disclosure may be a knitted fabric or a woven fabric, and is not particularly limited. Preferably, the base fabric 10 is a knitted fabric.
[0019] The adhesive layer 20 applied in the present disclosure may include an adhesive.
[0020] The category of the aforementioned adhesive includes but is not limited to polyurethane resin.
[0021] Referring to FIGS. 2A to 2D , which illustrate cross sectional views of manufacturing a down-proof fabric 50 in respective stages in accordance with the present disclosure. FIGS. 2A to 2D refer to some embodiments, but are not limited thereto. Referring to FIG. 2A , an embodiment includes coating a down-proof functional layer 30 onto a release paper 40 . The down-proof functional layer 30 includes a plurality of voids 32 . Referring to FIG. 2B , in order to dispose an adhesive to form an adhesive layer 20 , the adhesive is preferably mixed with a solvent to form a mixed reagent (unillustrated), and then the mixed reagent is coated onto the down-proof functional layer 30 and partially dried to form a pre-adhesive layer 22 . Subsequently, referring to FIG. 2C , the exposed side (i.e. the side not in contact with the down-proof functional layer 30 ) of the pre-adhesive layer 22 is adhered to the base fabric 10 and then completely solidifies to form an adhesive layer 20 . Lastly, referring to FIG. 2D , the release paper 40 is removed, and a down-proof fabric 50 is formed.
[0022] To evenly adhere the adhesive layer 20 of the instant application to the base fabric 10 , preferably at the stage of partial drying of the mixed reagent, the mixed reagent is not completely dried and solidified to retain some solvent therein. When the pre-adhesive layer 22 adheres to the base fabric 10 , the pre-adhesive layer 22 still retains some softness and fluidity due to incomplete solidification. Thus some of the mixed reagent will flow into the voids of the base fabric 10 , facilitating even adhesion to the base fabric 10 and also strengthening fixation. After a while of standing for the complete drying and curing (with complete removal of the solvent), an adhesive layer 20 evenly adhered to the base fabric 10 is obtained.
[0023] For instance, a solid content of the mixed reagent before coating is deployed to be 30 wt % (with the content of the solvent at 70 wt %). After the procedure of partial drying, the solid content of the mixed reagent would rise to 70 wt % (with the content of the solvent at 30 wt %). After further standing and curing, the mixed reagent would be completely dried to form an adhesive layer 20 .
[0024] The range of the solid content in the mixed reagent is not particularly limited, and can be modified to facilitate coating depending on the categories of the adhesive and the solvent.
[0025] The category of the aforementioned solvent includes but is not limited to methyl ethyl ketone, ethyl acetate, or dimethylformamide.
[0026] Methods for coating the mixed reagent applied in the present disclosure are not particularly limited, and may be selectively chosen in account of the convenience of implementation. The coating method includes but is not limited to spin coating, wire bar coating, dip coating, slit coating, dot coating, or roll-to-roll coating.
[0027] During the process of the flowing of the mixed reagent of the pre-adhesive layer 22 into the voids of the base fabric 10 , the yarn structure of the base fabric 10 would destruct the continuity of the pre-adhesive layer 22 , which enables air to permeate through the voids and give rise to the effect of air permeability.
[0028] For further improve the overall efficiency of air permeability, dot coating is preferably adopted to dispose the mixed reagent.
[0029] Hence, the adhesive layer 20 of the present disclosure is substantively continuous or discontinuous.
[0030] A thickness D 1 of the adhesive layer 20 (excluding the portion flowing into the base fabric 10 ) is preferably in a range of 1 μm to 10 μm, more preferably 1 μm to 8 μm, and the most preferably 1 μm to 5 μm.
[0031] Methods for coating the down-proof functional layer 30 applied in the present disclosure are not particularly limited, and may be selectively chosen in account of the convenience of implementation. The coating method includes but is not limited to spin coating, wire bar coating, dip coating, slit coating, blade coating, or roll-to-roll coating.
[0032] In order to maintain fine flexibility of the down-proof fabric 50 and sustain the wearing comfort as well as good hand feeling with sufficient down-proof effect, a thickness D 2 of the down-proof functional layer 30 is preferably in a range of 1 μm to 10 μm, more preferably 1 μm to 8 μm, and the most preferably 1 μm to 5 μm.
[0033] The material adopted in the down-proof layer 30 is made of a down-proof composition. The down-proof composition includes a polyurethane resin and an anti-slip agent.
[0034] Referring to FIG. 3 , the down-proof functional layer 30 has a plurality of voids 32 , and a size D 3 of the void 32 is in a range of 0.2 μm to 10 μm.
[0035] In one embodiment, the formation of voids 32 is due to the incomplete miscibility between the polyurethane resin and the anti-slip agent, along with the exertion of a shear force by a blade or a wire bar when the down-proof functional layer 30 is coated. As a result, voids 32 are formed in the coating film. However, formation of voids 32 is not limited to the foregoing mechanism only.
[0036] Since the thickness D 2 of the down-proof functional layer 30 is thinner than the conventional coating films with down-proof functions (with a thickness of about 30 μm). Also, the plurality of voids 32 of the down-proof functional layer 30 facilitates air permeability, which makes the down-proof fabric 50 more breathable than conventional down-proof coating films without voids or down-proof fabrics with lined down-proof cloth.
[0037] In the embodiments of the present disclosure, the range of the static friction coefficient of the surface 34 of the void 32 is between 0.39 and 1. When the down is going to penetrate through the void 32 , the down contacts the surface 34 of the void 32 . Since the effect of the static friction, the down is inhibited to move outward any further. Penetration of the down is prevented thereby.
[0038] Due to the uniform composition of the down-proof functional layer 30 , the static friction coefficient of the surface 34 of the void 32 inside the down-proof functional layer 30 and the static friction coefficient of the surface 36 of the down-proof functional layer 30 are the same.
[0039] In the embodiments of the present disclosure, a proper range of a solubility parameter of the anti-slip agent is chosen to manipulate the size D 3 of the void 32 . The down do not penetrate through owing to the overly large size D 3 even when the void 32 is formed. More preferably, a solubility parameter of the anti-slip agent is in a range of 9 to 10 (cal/cm 3 ) 1/2 to effectively manipulate the range of the size D 3 .
[0040] If the weight percent of the anti-slip agent in the down-proof functional layer 30 is too low, the static friction coefficient on the surface 34 of the void 32 will be too low. The down-proof functional layer 30 would fail to prevent the penetration of the down. On the other hand, if the weight percent of the anti-slip agent is too high, it forms too many voids 32 and thus the structural strength of the down-proof functional layer 30 will be influenced. Thus, the anti-slip agent has a preferred concentration of 2 wt % to 10 wt % in the down-proof functional layer 30 .
[0041] In one embodiment of the present disclosure, the anti-slip agent is polysiloxane resin.
[0042] In one embodiment of the present disclosure, the anti-slip agent is a comb-like acrylic polymer.
[0043] The aforementioned comb-like acrylic polymer comprises a chain X
[0000]
[0000] and a chain Y
[0000]
[0000] and when the chain X is 100 parts by weight, the chain Y is in a range of 40 to 60 parts by weight, wherein n is 14 to 18.
[0044] For example, in one embodiment of the present disclosure, the anti-slip agent can be a polymer I, having a chain combination:
[0000]
[0000] and when the chain X 1 is 100 parts by weight, the chain Y 1 is 55.56 parts by weight.
[0045] In another embodiment of the present disclosure, the anti-slip agent can be a polymer II, having a chain combination:
[0000]
[0000] and the chain X 2 is 100 parts by weight, and the chain Y 2 is 50 parts by weight.
[0046] In another embodiment of the present disclosure, the anti-slip agent can be a polymer II, comprising a chain:
[0000]
[0047] The following polymer IV, V and VI is not suitable for the present disclosure, due to the undesired range of the solubility parameter of the anti-slip agent. Polymer IV has a chain combination as follows:
[0000]
[0000] and when the chain X e is 100 parts by weight, the chain Y 1 is 66.67 parts by weight.
[0048] Polymer V has a chain combination:
[0000]
[0000] and when the chain X c2 is 100 parts by weight, the chain Y c2 is 56.82 parts by weight.
[0049] Polymer VI has a chain combination:
[0000]
[0000] and when the chain X e3 is 100 parts by weight, the chain Y c3 is 133.33 parts by weight.
[0050] The polyurethane resin in the present disclosure is not particularly limited and can be hydrophilic polyurethane resin or hydrophobic polyurethane resin.
[0051] The polyurethane resin in the present disclosure is not particularly limited and can be solvent type polyurethane resin or non-solvent type polyurethane resin (also called reactive type polyurethane resin). In an embodiment of the present disclosure, for the convenience in the process and the handy operation of the equipment, the solvent type polyurethane resin is preferred.
[0052] The following are some embodiments which illustrate more details of the present disclosure. The embodiments are herein presented for explaining rather than limiting the present disclosure. The scope of the present disclosure should be defined in the claims that follow.
[0053] Chemicals and Equipment
[0054] The chemicals and equipment need to be used in the present disclosure are listed as follows:
1. Polyurethane: Gicap Development Co., product model ADB585; solid content is 30 wt %, and the solvent is Dimethylformamide. 2. Anti-slip agent A: Far Eastern New Century Company, product model NF14, or polymer I as aforementioned; solid content is 10 wt %, and the solvent is Butanone. 3. Anti-slip agent B: Far Eastern New Century Company, product model NF16, or polymer II as aforementioned; solid content is 10 wt %, and the solvent is Butanone. 4. Anti-slip agent C: Far Eastern New Century Company, product model NF18, or polymer III as aforementioned; solid content is 10 wt %, and the solvent is Butanone. 5. Anti-slip agent D: Cherng Long Company, product model CL-209; polysiloxane resin; solid content is 10 wt/o, and the solvent is Ethyl acetate. 6. Anti-slip agent E: Far Eastern New Century Company, product model NF12, or polymer IV as aforementioned; solid content is 10 wt %, and the solvent is Butanone. 7. Anti-slip agent F: Far Eastern New Century Company, product model NF19, or polymer V as aforementioned; solid content is 10 wt %, and the solvent is Butanone. 8. Anti-slip agent G: Far Eastern New Century Company, product model NF22, or polymer VI as aforementioned; solid content is 10 wt %, and the solvent is Butanone. 9. Anti-slip agent H: Taiwan Wax Company, product model WAX-156. 10. Anti-slip agent I: Taiwan Wax Company, product model WAX-180. 11. Adhesive: Gicap Development Co., product model ADM411; solid content is 30 wt/o, and the solvent is Toluene. 12. Contactless injection type dot coating machine: Ming Hao Company, product model MJET-C-2. 13. Static friction coefficient tester: Testing Machines Inc., product model 32-07 monitor/slip and friction. 14. Air permeability tester: Go-in International Co., product model FX3300 IV.
Embodiment 1
[0069] The method for preparing the fabric having down-proof function, including the following steps:
1. 9 kg Polyurethane resin and 1 kg anti-slip agent A were mixed to form a mixed solution. 2. Blade was used to dispose the mixed solution on the release paper (Hui Jen Shih Yeh company, the product number is Black silk) to form a wet film with a thickness of 20 μm. Then a down-proof functional layer with a thickness of 5 μm was obtained by heating in an oven at 130° C. for 3 minutes. 3. 5 ml adhesive was provided in a contactless injection type dot coating machine to dispose on the down-proof functional layer by a thickness of 80 μm, and then heated in an oven at 130′C for 6 minutes. The resulting incompletely solidified pre-adhesive layer with a thickness of 30 μm was yielded. 4. A knitted fabrics with 30d/36f was used as the base fabric and a roller was used to apply a 2.5 kg pressure onto the knitted fabrics to have evenly adhered to the pre-adhesive layer. After 24 hours a completely solidified adhesive layer was obtained. Finally, the release paper was removed to have a down-proof fabric.
[0074] Air Permeability Test
[0075] A down-proof fabric which was made by the above method was cut into the size of 7 cm×7 cm and then be placed on a air permeability tester. Standardized testing method ASTMD 737 was employed. The test area was 38 cm 2 , and the test pressure was 125 Pa. The test result was listed as Table 1.
[0076] The maximum static friction coefficient test
[0077] Two down-proof fabrics which were made by the above method were stacked where the faces having the down-proof functional layer of respective fabrics were opposing to each other. Static friction coefficient tester was used to investigate the maximum static friction coefficient of the surface of the down-proof functional layer.
[0078] The test result was listed as Table 2.
[0079] Down-Proof Effect Test
[0080] This embodiment was performed under the Nike standard test NAL™ 9100 VI. Intertek Company was commissioned to conduct the test.
[0081] Test Steps were as Follows:
[0000] 1. Manufacturing knitted fabrics pillow stuffed with down: Two down-proof fabrics which were made by the above method were cut into the size of 17 cm×17 cm and stacked up. After stitched three sides at 1 cm inwardly away from each edge, 12 g of down was stuffed into (75% feather/25% down). Sewed up the last one edge to make a small pillow.
2. Washed the small pillow in a washing machine at 40° C. (water 2 kg with detergent 1 wt %) for 10 minutes each time, and washed three times continuously.
3. Used tumble dry low at about 50° C. Observed the exterior of the pillow and then counted the penetration number of the down. Used the method of NAL™ 9100 VI as the standard. It was qualified when the number of the down penetration count was less than 60. Test result was listed as Table 2.
Embodiments 2 to 4
[0082] The method in the embodiment 2 to 4 are the same as that in embodiment 1, except that the anti-slip agent was B, C and D, respectively.
Comparison Embodiments 1 to 5
[0083] The method in the comparison embodiments 1 to 5 are the same as that in the embodiment 1, except that the anti-slip agent was E, F, G, H and I, respectively.
[0000]
TABLE 1
Air permeability
(cm 3 /cm 2 /s)
Embodiment 1
0.56
Embodiment 2
0.13
Embodiment 3
0.12
Embodiment 4
0.46
Comparison embodiment 1
1.32
Comparison embodiment 2
0.23
Comparison embodiment 3
0.66
Comparison embodiment 4
0.34
Comparison embodiment 5
0.51
[0000]
TABLE 2
The
solubility
maximum
parameter of
Down-
static friction
anti-slip agent
Void size
proof
coefficient
(cal/cm 3 ) 1/2
(μm)
test
Embodiment 1
0.545
10
10
Qualified
Embodiment 2
0.471
9.6
2
Qualified
Embodiment 3
0.416
9.4
2
Qualified
Embodiment 4
0.392
9.1
8
Qualified
Comparison
0.602
10.5
20
Unqualified
embodiment 1
Comparison
0.383
9.3
4
Unqualified
embodiment 2
Comparison
0.346
8.9
12
Unqualified
embodiment 3
Comparison
0.312
9.2
6
Unqualified
embodiment 4
Comparison
0.289
9.0
10
Unqualified
embodiment 5
[0084] From the air permeability test according to Table 1, it can be found that the void resulted from adding proper anti-slip agent can improve air permeability. Generally, the air permeability of breathable windproof fabric is between 0.1 and 1 (cm 3 /cm 2 /s). In the embodiments 1 to 4, the air permeability of each was improved significantly in comparison with the conventional down-proof fabric, with positive feedbacks from the wearers. In comparison embodiment 1, the void is so large that the air permeability is as high as 1.32 (cm 3 /cm 2 /s). When being put on, the person who wears it can feel the wind so that no sufficient windproof effect was achieved. It is not a good option for a down-proof fabric.
[0085] From the embodiments 1 to 4 according to Table 2, when the maximum static friction coefficient of the surface of the down-proof functional layer is larger than 0.39, there is enough static friction that can prevent the penetration of the down and thus achieve good down-proof efficiency.
[0086] From the comparison embodiments 2 to 5 according to Table 2, when the maximum static friction coefficient of the surface of the down-proof functional layer is less than 0.39, there is not enough static friction that can prevent the penetration of the down. After washing for three times in washing machine, the down penetration count was more than 60. No down-proof effect is achieved.
[0087] In addition, from the comparison embodiment 1 according to Table 2, one can realize that if the solubility parameter of the chosen anti-slip agent is larger than 10 (cal/cm 3 ) 1/2 , the resulting void will be too large (void size is 20 μm) owing to the poor miscibility of the anti-slip agent and the polyurethane resin. Even though the maximum static friction coefficient of the surface of the down-proof functional layer is larger than 0.39, it still fails to effectively prevent the penetration of the down.
[0088] While the foregoing is directed to particular embodiments of the present disclosure, the embodiments are not limiting the invention and, by any person skilled in the art, other and further embodiments of the disclosure may be devised without departing from the basic scope of the disclosure. The scope of protection of the present invention shall thus be dictated by the claims follow.
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A down-proof fabric includes a base fabric, an adhesive layer disposed on the base fabric, and at least one down-proof functional layer disposed on the adhesive layer. The down-proof functional layer includes a plurality of voids to block the penetration of the down. The present disclosure improves the drawbacks of conventional down-proof techniques and provides a light, thin, and breathable down-proof fabric with good hand feeling.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application No. 61/505,874, filed Jul. 8, 2011, the entire contents of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a new media art form, and more particularly to an interactive media art form, which displays visually changing color patterns in response to one or more supplied data streams, either in real time or as playback of stored data on a woven, threaded surface of fiber optic threads.
Throughout the ages, and continuing to present times, weaving has and continues to epitomize social interaction. Textiles have a shared history throughout the world's cultures and are common throughout time. In European culture, medieval tapestries told narratives, and in the 21st century, we find our stories threaded and networked throughout the web.
Electronic optical art technologies, such as a liquid crystal displays (LCDs), field-emission displays (FEDs), and plasma display panels (PDPs) have been heretofore described for displaying various images in a form embodying a relatively thin profile, such that such displays are suitable for wall mounting or portable applications.
However, traditional woven crafts have not heretofore been employed for display of dynamically changing patterns.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a new media art form that synergistically blends traditional textile arts with contemporary communication materials and processes to redefine the role of a tapestry in contemporary culture, and provide a visual “weaving” of information, which can function as a dynamic data visualization screen or mural.
It is a still a further object to create a computer controlled fiber optic tapestry which fuses traditional arts, digital electronics, interactivity, and data scraping with contemporary art.
These and other objects of the invention are achieved by utilizing one or more meshes of woven fiber optic threads that each comprise a woven fiber optic panel of the present invention. Each panel is lightable by arrayed light sources optically coupled at a peripheral border of the panel, all of which is enclosed within a housing.
The fiber optic panel serves as a new media canvas for display of images “woven” from optically converted information, using fiberoptic filaments to carry and display the optically converted information and data from a suitable source, for example, the Internet, in the form of changing light patterns and/or colors, which can be programmed to change with variable speeds and durations. The fiber optic panels are woven to create a tapestry capable of emitting light. It is noted that the term “tapestry” is being used to refer to a woven mural design made up of woven fiber optic threads, since not all weaves meet the literal requirement of the term “tapestry.”
When the fiber optic panels are woven on a handloom, the weaving process automatically etches or abrades the fiber optic surface of the individual fibers, allowing light to be emitted along the length of the fibers. The light sources are controlled by a computer responsive to information collected from a selected external source, for example, as in this invention, the Internet, which is converted to light emission data for displaying emitted light as a changing color pattern on the surface expanse of the tapestry. Other external sources may be used to trigger the light patterns, such as sound, video or audio or movement detected through various sensors.
The fiber optic woven “tapestry” functions as a data visualization canvas, which displays information on its surface as woven light. The surface is animated and dynamic based on various data sources and sets including, but not limited to, TWITTER. It can also read flight information from airport arrivals and departures, scraping a database that supplies this real time information. The tapestry according to an embodiment of the invention has further potential to read and display, in abstract dynamic light patterns, other exemplary data sets, such as stock market quotes, or energy usage/or energy efficiency in a green building so as to create a visual thermostat.
The optical tapestry according to the invention could optionally serve as a sonically or visually interactive surface, using sound to trigger the surface patterning or a video camera to interact with movement from an exterior real time source in order to provide such patterning. Additionally, the tapestry can respond to data from a customized website, or other types of data.
The tapestry is also optionally addressable by smart phones. The tapestry can also be controlled with commands to display specific pre-programmed patterns. It can be conceivably programmed using TWITTER TWEETS to panel display particular colors and patterns.
The patterns and light variations that are displayed on the panel's surface are all predetermined and predefined, and their timing and transitional rates are assigned. As such, these are not randomly blinking lights. However, they also could be such.
In a particularly advantageous embodiment, the woven optical fiber panels are optically coupled at a periphery thereof to suitable color controllable light sources, for example, RGB LEDs to illuminate the warp and the weft. The LEDs are computer controlled and programmed to change color and pattern so as to be responsive to the conversion of the aforementioned collected information.
In accordance with an embodiment of the invention, the computer controlling the display on the tapestry parses information from TWITTER and other data sources to display color, light and pattern onto multiple fiber optic panels according to the invention using the color variable light sources, for example, the RGB LEDs mentioned above. The resulting real-time animation is an abstract, data visualization that continually updates as data changes.
The tapestry display, and assembly thereof, comprises one or more woven fiber optic panels that are created, for example, by conventional weaving techniques, using plastic fiber optic thread. The fiber optic threads are optionally woven in a weft faced 20 four-harness satin weave, known as a “satin weave construction.” Other weave structures can be used as well. As in all woven textiles, the panels have warp and weft threads.
As mentioned above, a natural etching of the fiber optic threads occurs as a result of abrasion from the weaver's shuttle on the surface of the plastic fiber optic threads and the thread's contact with the loom's sand bar. The surface of the threads may be further advantageously etched or scratched by hand so as to allow for an enhanced diffusion of light therethrough. Each fiber optic mesh also has warp and weft end threads. All sides are free, allowing them to connect to the RGB LEDs.
A portion of the electronics enabling controlling of the LEDs are housed conveniently on electronic circuit boards, each board consisting, for example, of four integrated circuits (IC). Each IC controls a time manageable number of LEDs, for example, ten. There is a transreceiver chip on each board that sends commands to all four ICs. Each board, in such example, has forty RGB LEDs. This allows programming and control of each LED individually for color and luminosity.
A housing is provided, conveniently in the form of a four (4) sided, optionally metal or plastic box, with a window cut in the front. The box houses four of the aforementioned circuit boards on inner walls of the box, one on each of four sides thereof. The woven fiber optic panel described above is sandwiched between two clear Plexiglass plates and this sandwich is then attached to the inside of the front window of the housing. This sandwich is advantageously locked into place within and to the housing a conventional type, or custom designed, locking tab.
The end threads of the woven panels are attached to the RGB LEDs through light guides in the form of coupling plugs, made conveniently from black, heat shrink tubing, and each is advantageously fitted with a mirror MYLAR inner lining, which enhances the reflection of light. This entire construction is advantageously designed to be non-adhesive, so as to allow the assembly to be broken down into its basic components of circuit boards, fiber optic panel, light-guides (plugs) and housing.
An example of suitable configuration software for implementation of the invention is MAX MSP. MAX may be used to program RGB values for the LEDs, and can make pattern animations by programming fades. The boards are programmed using suitable software, such as, for example, MAX. All of this information is stored in the nonvolatile memory of the ICs of the circuit boards.
As a particular display embodiment in accordance with the invention is developed, a combination of programming languages is generally used. For example, PYTHON to use data from the Internet to control and trigger patterns on the fiber optic panels, MAX for testing and perhaps for standalone visualization pieces that are not triggered by Internet data. The program PURE DATA can also optionally be used to trigger the panels with sound. Both PYTHON and PURE DATA are open source software. MAX is an open license for use with APPLE products.
In practice, the warp and weft ends of the woven fiber optic meshes are connected to the RGB LEDs that are electrically connected (e.g., soldered) to the circuit boards. The boards are connected to and controlled by a computer, as shown in FIG. 9 , which is for example, on-line, on the Internet, scraping databases for specific information. These programs are also designed to operate from the computer hard drive as files. It will therefore run live from the Internet and/or as a file stored on the computer's hard drive. As will be understood, one or more of the IC boards and the computer comprise a data interpretation device for implementing the invention, and in which the term “computer” comprises, optionally, a conventional desktop or laptop computer, a smartphone or any other device capable of digital processing, transmission and/or reception of a digital signal; in which the data interpretation device is contemplated to be communicable with the tapestry of the present invention through a wired connection, though a wireless connection is also contemplated.
A search is carried out for pre-determined language using, for example, PYTHON, for data scraping. In accordance with an example of the invention, words are pre-assigned a numeric value such that the words comprise a specific data that is receivable by the data interpetation device and correlated with the pre-assigned value, for example, so as to define a color and pattern that is translated onto the surface of the woven fiber optic canvas. For example, the word “people” is assigned an RGB value of 255-255-0 (Pure yellow), and triggers the first group of 20 LEDs on to the weft of the fabric, depending on the frequency by which the word is said. The display of the pattern is pre-defined by the number of times the word is said in a given time frame, which frequency is also optionally a specific data. The colors are RGB, and transition rates vary from on/off to an imperceptible transition that can last for hours. Each of these aspects including, optionally, the aforementioned pattern, colors and transition rates are combinable so as to provide and correlate to a specific representation of the specific data. As provided for herein, other types of specific data may also optionally comprise sound, relative information between one or more predetermined items and/or interactive information.
All activity on the surface of the fiber optic canvas is prompted by either real time information (i.e., received as data input live from the Internet or other inputs), or by recorded information (i.e., information drawn from a prerecorded archive of data implemented in playback mode).
A working example of the tapestry called “50 Different Minds” debuted prior to the filing of Applicant's U.S. Provisional Patent Application No. 61/505,874 at the San Jose Museum of Quilts and Textiles as part of the Zer01 Festival in San Jose, Calif. The piece measured 50 by 50 inches. It displayed patterns and colors that related to TWITTER TWEETS of color words. It also used air traffic data from the nine busiest airports in the U.S. Horizontal and vertical lines on the tapestry's surface moved in real-time, and were synchronized with the longitude and latitude of arriving and departing flights.
Visitors could also interact with the tapestry by tweeting additive and subtractive color names. The tapestry is programmed to display colors in response to TWEETS written using the expression “#optictapestry,” and then primary and secondary color words, like “blue,” “red,” “yellow,” “magenta,” “cyan,” etc.
In San Jose at Zer01, the tapestry consisted of nine (9) individual woven fiber optic panels, measuring a total of 50×50 inches, see FIG. 9 . The inspiration for the patterns and colors derived from the color theory of painter Josef Albers and his wife Anni Albers' work in textiles.
While on display in San Jose, the tapestry was connected to the Internet and scraped data in real time. There are four routines for 50 Different Minds. Two computer programs drive the surface animation, one of which listens for TWITTER TWEETS, and the other of which follows flight arrivals and departures at the nine busiest airports in the U.S. Specific search terms are associated with patterns and color frequencies. When queried, information is parsed and assigned a pattern, which triggers a display of changing pattern and/or color. The animated effect looks like illuminated silk.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial plan view of a woven fiber optic thread panel according to an embodiment of the invention;
FIG. 2 is perspective view of a fiber optic panel housing according to an embodiment of the invention;
FIG. 3 is an explanatory view depicting a manner of coupling light sources with the fiber optic threads via light-guides (plugs);
FIG. 4 is a partial cross-sectional view of the light-guide (plug) and LED of FIG. 3 ;
FIG. 5 is an illustration of a particular illumination of the tapestry according to the invention;
FIG. 6 is a perspective view of an interior side of a fiber optic panel housing according to the invention; and
FIG. 7 is a perspective view of an assembly of a plurality of fiber optic panels according to the invention shown adjacently arranged, and in which a portion of the housing is removed to illustrate at least the panel contained respectively therein.
FIG. 8 is an illustration of the wall mounting system for use with a tapestry module of the present invention.
FIG. 9 is an illustration of the tapestry of the present invention comprising nine (9) modules and woven fiber optic panels thereof.
DETAILED DESCRIPTION OF THE INVENTION
A representative example of the invention, and its manner of construction and use, is embodied in the following description, and is directed to an operational system which has actually been constructed and operated. It is noted, that while serving as a concrete example of the structural configurations, hardware and software for implementing a working model of the media art form according to embodiment of the invention, the specific details are intended merely as being representative of one possible approach to construction, as well as just a few examples of various operational modes (routines). Many other alternative structural components and operating modalities (software and routines) are contemplated within the scope of the invention.
In accordance with the example, and as partially depicted in FIG. 1 , fiber optic threads 1 woven in a pattern forming a fiber optic woven mesh 3 and comprising a woven fiber optic panel 10 of the present invention is shown in a weft faced 4-harness satin weave with a stitching 2 , see FIG. 4 , sewn around all four sides to restrain the individual threads 1 . The hem 2 is sewn with a polyester thread, but could alternatively be sewn with a monofilament or thin thread as well. The fiber optic woven panel 10 of the example measures 12×12 inches and is woven on a hand loom.
When weaving of the panel is complete, it is subsequently flattened using a heat-set press for 3-5 minutes at a temperature of 250 degrees.
A natural etching of the fiber optic threads 1 occurs as a result of abrasion from the weaver's shuttle on the surface of the plastic fiber optic threads 1 and the sand bar, which is part of a hand loom. The surface of the threads 1 are further advantageously scratched using a light sand paper and/or a scapel knife to scrape the surface allowing more light to leak along the length of each of the fiber threads 1 , which would otherwise remain within each of the threads 1 over its length.
In looking to FIG. 2 , a lighting module 20 defines a panel housing 21 comprising, optionally a metal or plastic frame having approximately a 15.5″ outer dimension and a rim thickness of approximately ⅛″. Housing 21 encloses the woven panel 10 , which optionally comprises etched fiber optic thread (Mitsubishi CK-20 Eska 5 mm). Portions of the housing 21 are conveniently cut on a laser cutter and joined using, a suitable bonding material, for example, Weld-On 3 solvent. On the inside of the housing, an inner 1/16″ thick Plexiglass window 22 comprising two plates 25 of museum non-reflective Plexiglass each having an edge 23 and measuring 12×12 inches are provided and held in place with Plexiglass locking tabs (not shown) in each corner of the housing 21 . The fiber optic panel 10 is sandwiched between the plates 25 .
As depicted in FIGS. 3 and 4 , groups 31 of four to five fiber optic thread ends are fed, as at “A,” perpendicularly from the panel 10 edges into a reflective connector, referred to herein as a light-guide (plug) 32 , as at “B,” which is made, for example, from 5 mm heat shrink tubing (3:1 polyolefin, HS3-0188, black). The fiber optic threads 1 measure ⅞ inch to 1 inch in length from the end of the weave structure to the end of the thread.
The light-guides (plugs) 32 are conveniently handmade by heat shrinking them using a silicon mold which has multiple conical forms customized to the size of the RGB LEDs and baked at a temperature of 220 degrees in an oven. They are lined with a square of reflective MYLAR 33 measuring ⅝ inch square. The MYLAR squares are inserted by handrolling them into the light-guide's (plugs) 32 heat-shrink casing.
The light-guides (plugs) 32 are attached to lights, as at “C” and “D,” by sliding them over the tip of a Red-Green-Blue (RGB) light emitting diode (LED) 34 (for example, Superbright RGB 599R2GBC-CA) mounted on a printed circuit board (PCB) 35 . The placement of the fiber optic thread ends in relation to the tip of the RGB LEDs varies ¼″ to 1/16″ from the end of the thread to the front tip of the LED surface when fully assembled, as shown at “E.”
The PCB (12 inches×1 inch) spans the edge of the panel 10 and secures forty RGB LEDs, four microcontrollers (Motorola PIC18F4620-I/P), supporting power circuitry (including capacitors, crystals, transistors and resistors), and a serial data transceiver circuit (MAX483 RS-485). There is one board 35 on each side of the four-sided housing 21 .
The module 20 is designed so that the fiber optic mesh, above electronics and PCBs, and the housing can be assembled and disassembled with respect thereto so as to be containable within the housing, as shown in FIG. 6 .
Therein, the circuit boards 35 are held in place by with 6/32 nylon screws, ¾″ in length. Each microcontroller controls ten RGB LEDs and applies independent pulse width modulated (PWM) signals to the red, green, and blue terminals of the LEDs and holds a unique chip identification number (ID) in nonvolatile memory space.
Four identical PCBs, one per side of the module 20 , are attached to the woven panel 10 and are supplied with remote power and serial data. A 5V 50 amp power supply and 4 power jumpers per module 20 , and multiples thereof, are contemplated for use in providing sufficient power.
Data is transmitted from a Lantronix XPort Direct Plus (XPD100100S-01 ethernet-to-serial converter). There is one ethernet to serial converter per three panels in a tapestry construction comprising nine (9) modules 20 , see FIG. 9 , in which a set of three modules 20 is operatively connected mechanically in series and to data lines in order to receive and display information that is the same or similar. The data lines are connected in parallel to the three modules 20 using flat flex cables. Additionally, there are three flat flex cables per module 20 .
Each data converter is assigned a static Internet protocol (IP) address, connected to an Internet switcher (Cisco SD205 Switch—5 ports), and receives formatted display data from a computer program. The number of identical lighting modules connected to the data converter is limited only by electrical factors and the microcontroller ID space.
The formatted display data is a standard UDP packet transmitted to the static IP address of the data converter and containing standard 8 bit RGB color data, the ID of the target microcontroller, and specifying the affected LEDs. This packet is received by the data converter and the color and target data is transmitted on a wired serial data line.
Each connected microcontroller checks the ID in the serial data and parses that data if that ID matches the number stored in memory. The RGB color data is converted to three PWM signals which are fed to the specified LEDs. These signals affect the power each basic color in the LEDs receives and thus the perceived color is displayed in the attached fiber optics. The microcontroller maintains this output until another serial packet is parsed. The entire system is updated by scanning through each microcontroller with display data.
The software for the fiberoptic tapestry installation consists of several layers of code written in the PYTHON language. The lowest level sends raw binary commands to the device over UDP (User Datagram Protocol) which the Lantronix UDP UART (Universal Asynchronous Receiver/Transmitter) device translates into serial commands to the hardware. The next highest level, the API (Application Programmer's Interface), translates drawing commands into low level binary commands. Examples of such commands allow the programmer to set the color of columns and rows, or change colors. Next, individual routines execute specific sequences of drawing commands to create the different content “programs,” e.g., air traffic data. The final layer, the “harness,” executes the different content programs in a rotating sequence.
Each of the computers or computer 37 used in conjunction with the tapestry of the present invention, and supporting apparatus including, for example, the aforementioned power supply, UDP, and converter are, optionally, housed in a separate equipment box (not shown).
The following describes examples of routines (referred to by the names “Comings and Goings,” “Prelude,” “Fifty Different Minds” and “Tweet Suite”) to assist in an understanding of the versatility of the invention in practice.
It is to be understood that the tapestry comprising the invention may comprise a single module 20 or multiples thereof.
Comings and Goings
Comings and Goings is an air traffic routine that visualizes the incoming and outgoing air traffic at major airports around the U.S. In the aforementioned invention, the program module scrapes flight data from nine (9) of the busiest American airports. Each square panel in the tapestry represents a single airport while the warp and weft encode incoming and outgoing air traffic. A single LED that illuminates a bundle of four to five threads represents a flight and its distance from the airport is encoded in the position within the panel 10 . Incoming flights are drawn as horizontal threads where the bottom of the panel 10 represents the airport. As flights land and get closer, the lines move from top to bottom. As flights take off and get farther from the airport, the lines move from left to right on the panel 10 . The bottom and left represent a distance of zero miles from the airport, while the extreme top and right represent distances of 30 nautical miles from the airport.
For each airport under consideration, the latitude, longitude, and airport code are encoded in the software. It periodically loops through the list of airports and makes a query to a public API at flightstats.com requesting flights in the airspace of each airport. Using a PYTHON module called “mechanize,” it retrieves the data which is returned in an XML format and contains the flight number, source, destination, and current position coordinates. The software then filters the list by removing any flight that is outside a 30 mile radius from the airport. The distance for filtering is the euclidean distance, i.e., sqrt[(longitude[airport] longitude[airplane])^2−(latitude[airport]−latitude[airplane])^2]. The incoming flights are then drawn as individual rows and the outgoing flights are drawn as individual columns. The position is determined by linear interpolation, mapping the range of 0-30 miles to the 160 threads in each direction. A flight 0 miles from the airport would be drawn at thread 0, a flight 15 miles would be drawn on thread 80, and so on.
In order to optimize the visual continuity of the drawing and give the illusion that the visualization is running in real time, the updated positions are slowly drawn over a period of time rather than all at once despite representing a snapshot in time. To accomplish this, an internal database is maintained with all the current flights. As the flight list is updated with each iteration, each flight is compared with the database and is determined to have changed or not. If the position has not changed since the last update, it will not be drawn. The average period of time required to draw the flights is then divided by the number of updated flights to determine the spacing between updates. So if the display is intended to last for 60 seconds, and there were 10 flights with new positions, each of the 10 updated positions are drawn every 6 seconds. To eliminate the need to update the entire display for each drawing operation, an internal double buffer is maintained in software. Each time a drawing operation occurs, it is drawn into the buffer first and compared with what has been sent to the hardware. Only changes are sent to hardware to minimize bandwidth requirements and more importantly, to prevent flickering as slow updates are sent out.
Prelude
The prelude routine uses colors mentioned on TWITTER's global timeline to drive an animation stepping through the three primary color groups red, yellow, and blue, in that order. The array of nine panels is arranged in a square, having three rows and three columns. Each of these nine squares is in turn divided into four horizontal stripes. Colors mentioned are drawn on each of these stripes and then slowly consolidated until all nine panels share the same color using a sort of “tournament bracket” algorithm. The first consolidation makes each of the nine panels the dominant color of its four stripes, the second consolidation makes each row the dominant color of its three panels, and the last consolidation makes all nine panels the dominant color of its three rows.
For each of the three primary colors, there are four variants enumerated in a data file, each with a search term and a RGB (Red Green Blue) color definition. For example, the primary color red may consist of the search terms “crimson,” “blood,” “fire,” and “pink,” each bearing a unique color definition. If the search term is used anywhere in a TWEET, one “hit” is counted for that color. To balance the unequal number of results each term may generate, each of the four variants constituting a primary color receives an equal representation by searching back as far as possible to obtain 36 hits (one stripe for each of nine panels). Next, they are sorted by time of mention to create an ordered list generating the variations in the animation.
After downloading the data from the Internet, one of the nine panels is selected at random to animate. For this panel, the row stripes are “painted” in order from top to bottom by selecting its color from the top of the ordered list. After drawing the four horizontal stripes, the most common color is determined. Ties are broken randomly. The panel is then slowly faded to the most common color.
After drawing all four horizontal stripes and fading to the dominant shade, another panel is selected at random from the remaining un-painted nine panels and the procedure repeats.
Once all nine panels have been striped and faded to the dominant color, consolidation occurs row-wise. For each of the three rows top to bottom, the dominant color is determined and then the row fades to that color.
Lastly, the dominant color of the three rows is determined and the entire array of nine panels fades to that color. Once this occurs, the striping and consolidation routine occurs for the next of the three primary colors.
Fifty Different Minds
In the Fifty Different Minds routine, the following keywords (one, people, name, listening, red, different, color, minds, fifty) are used to create pseudo-random numbers which determine the size of various zones. To generate a pseudo-random number within a given range, the timestamp of a TWEET (a large, unique integer) containing one of the keywords is divided by the maximum of such given range and the remainder is returned—i.e. the modulus.
With reference to FIG. 5 , respective Zones 1 , 2 and 3 are provided and enable an illustration of exemplary LEDs 34 denoting each of the zones. In the routine, once every three seconds, Zone 1 is updated; every 5 seconds, Zone 2 is updated; every 7 seconds, Zone 3 is updated. Each update entails changing the color and the size of the zone with an approximately 5-second fade. Each zone is assigned a preprogrammed, looping sequence of three colors and the next in the sequence is used each time the zone is updated. Some zones may grow slightly from their nominal size—e.g. zone 1 , nominally the center panel of the nine-panel array, may grow vertically by one row of 10 LED's above and below, to two (2) rows above and below, creating a vertically-oriented rectangle. The color of the area taken by the expanded zone takes precedence over the color of the next nominally-larger zone.
If a zone is allowed to expand n steps above the nominal size, a random number of maximum value n is determined by the algorithm given above. A number of 0 corresponds to drawing the zone in its nominal size; a number of 1 corresponds to drawing the nominal area plus the area of the first defined expansion, and so on.
This sequence continues for a set number of seconds before rotating to the next program in the harness.
Tweet Suite
The final routine example, “Tweet Suite,” responds to TWEETS containing color words and the hash tag “#optictapestry” by creating outwardly-expanding concentric circles of color. Ripples is an interactive component of the invention. A person can send a TWITTER TWEET from their personal computer or smart phone from anywhere in the world using this hashtag command and the invention responds by displaying a color or pattern. The first color in the sequence is drawn on the smallest, innermost ring and slowly faded in over a random period of time ranging from 0.2 to 4 seconds. After the fade-in period, it is faded into the next larger ring as the next color in the sequence is faded in to the smaller ring, and so on. Black is added as the last color in the sequence to ensure the tapestry is completely off before moving to the next TWEET.
A database of color words and their RGB definitions is used to translate the colors found in a TWEET. If a color is not recognized, or is misspelled, it simply does not appear in the sequence. The routine does not run if there are no new TWEETS in the last fifteen minutes.
It is to be understood that the present invention contemplates a panel display comprising two or more adjacent modules arranged relative to one another, as shown in FIG. 7 . In such arrangement, the modules are shown from a backside of the tapestry with a backside of their housings 21 removed in order to show that one or more may be connected to one another, optionally through use of screws or other fasteners.
In this way, one or more of the modules of the modular display comprising a tapestry of the invention may receive information from an information source or device that is different than an information source or device supplying information to an adjacent module. This is the case as each individual module of the modular display can be specifically programmed and connected with its own information source or device.
In a particular configuration, the tapestry may be programmed to execute and exhibit one or more combinations of the aforementioned routines in a predetermined order thereof.
When displaying one or more combinations of the aforementioned routines, or other information which the tapestry is adapted to exhibit, it is further contemplated that instead of the sandwiched configuration of the woven fiber optic panel described herein, that such a panel, measuring, optionally, 12″ by 30″ be tacked with monofilament onto a Plexiglass frame. In this way, the woven fiber optic panel and illuminated surface provided thereby is exposed to the environment whereby the woven fiber optic panel is sewn to the Plexiglass frame in which the sewing material is passed through the woven fiber optic panel and then through the Plexiglass frame.
As such, each of the several modules of the modular display comprising a tapestry of the present invention may further be useable to display one or more types or categories of information. Each component of information may, for instance, be displayed by one or more of the modules whereby illumination of a particular panel may be faded and patterned according to programming, as discussed hereinabove, which is used to interpret the information.
It is to be further understood that the module display comprising several of the aforementioned modules so as to comprise a tapestry of the present invention is mountable on a wall surface through, as shown in FIG. 8 , use of a mounting system 38 comprising a first wall plate 39 that is attachable to a wall surface, and which provides cleats 40 to which a second wall plate 41 , and specifically a back surface 42 thereof with cleats 43 carried thereon, matingly engage. A front surface 44 of second wall plate 41 carries rails 45 onto which carriages (not shown) carried on a back surface of a modular housing 21 ride so as to comprise the tapestry of the invention when mounted to a wall surface. Each of the rails and carriage are contemplated to comprise a construction commensurate with an IGUS rail and carriage system. In this way, the display provides an informative and aesthetically pleasing device able to be easily incorporated within a household or office environment.
Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.
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A woven fiber optic tapestry for conveying a specific representation of data on a woven fiber optic threaded surface. The tapestry is provided in a particular system including fiber optic threads threadedly arranged together to form a woven fiber optic panel, in which each of the threads is operatively connected to a light source, and a data interpretation device operatively connected to the light sources so as to provide a transfer of a pre-assigned value of data from the data interpretation device to the light sources and the threads, the transfer of the pre-assigned value causing an illumination of the light sources so as to correlate to a specific representation of the data.
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BACKGROUND OF THE INVENTION
The present invention concerns a device for fixing a collapsible canopy to the roof of a trailer, a camper or the like.
In particular, the invention concerns a device for fixing a collapsible canopy to such a roof, whereby the device can be used to mount a canopy on practically any camper whatsoever or on practically any trailer whatsoever, and whereby the canopy, when being mounted, can be adjusted such that it fits perfectly onto the edge of the existing roof of the camper, the trailer or the like.
As the canopies which are known up to now can only be mounted in a single fixing position, a perfect connection between the canopy and the roof edge of the camper or the trailer is only rarely obtained.
Consequently, as there usually remains a slit between the canopy and the roof edge, the wind will have more hold on the canopy, such that the device for fixing the canopy has to resist greater loads.
The invention aims a device for fixing a collapsible canopy onto the roof of a trailer, a camper or the like, which remedies the above-mentioned and other disadvantages.
SUMMARY OF THE INVENTION
To this end, the present invention concerns a device for fixing a collapsible canopy onto the roof of a trailer, a camper or the like, which includes two parallel rails; a carriage on each rail which can move in the longitudinal direction of the rail; a clip, pivoting on the carriage, for fixing the collapsible canopy; and an adjustment element between each rail and the corresponding clip.
DESCRIPTION OF THE DRAWINGS
In order to better explain the characteristics of the invention, the following preferred embodiment according to the invention is described as an example only without being limitative in any way, with reference to the accompanying drawings, in which:
FIG. 1 represents a view in perspective of a roof onto which is fixed a canopy by means of a device according to the invention, with a partial section of said canopy;
FIG. 2 represents the part indicated by F 2 in FIG. 1 to a larger scale;
FIG. 3 represents a view analogous to that in FIG. 2, but whereby the device according to the invention has been dismounted;
FIG. 4 represents a cross section according to line IV—IV in FIG. 2;
FIG. 5 represents a cross section according to line V—V in FIG. 1, to a larger scale;
FIG. 6 represents the part indicated by F 6 in FIG. 5 to an even larger scale;
FIGS. 7 and 8 represent views to a smaller scale, analogous to those in FIG. 5, but whereby the connecting section is situated in its highest position, in its lowest position respectively.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A device according to the invention for fixing a collapsible canopy 1 onto the roof 2 of a trailer, a camper or the like 3 consists of at least two rails 4 - 5 over which are mounted moving carriages 6 . The rails 4 - 5 are fixed crosswise to the edges 7 of the roof by means of L-shaped sections 8 and screws 9 .
The rails 4 - 5 are preferably made of tubular sections having a rectangular cross section with a longitudinal groove 10 on their top side, such that also other accessories such as luggage grids or the like can be fixed onto these rails.
The carriages 6 are mainly made of a section whose shape is that of an inverse omega, whose bottom 11 is provided under the corresponding rail 4 - 5 and whose sides 12 - 13 are provided next to the above-mentioned rails. Finally, the protruding walls 14 - 15 of this inverse omega-shaped section have fixing edges on their far ends placed in another position 16 - 17 , whereas ribs 18 - 19 and 20 - 21 respectively which are directed towards one another, are provided on the free end of the fixing edges 16 - 17 as well as on the side which is adjacent to the walls 12 - 13 .
Over the corresponding rails 4 - 5 , each carriage 6 is made of a connecting bridge 22 which is fixed onto the protruding walls 14 - 15 , for example by means of welding.
Said connecting bridge 22 is equipped, in its top part, with a tooth 23 which is more or less T-shaped and which extends in the longitudinal direction of the connecting bridge 22 . The head of said T-shaped tooth 23 has curved, lateral surfaces 24 - 25 , and the top wall of said tooth 23 has a rib 26 .
The device according to the invention further consists of a clip 27 which successively represents, as of the front edge to the back edge, a hook 28 which is directed upward, a downward directed groove 29 , a second upward directed hook 30 and a duct 31 provided over it.
The above-mentioned groove 29 preferably has curved, lateral walls 32 - 33 which are mutually connected via the bottom 34 of the groove 29 .
The above-mentioned duct 31 consists of three walls 35 - 36 - 37 , whereby ribs 38 - 39 which are directed towards one another are provided on the walls 35 - 37 .
In the walls 35 - 37 are provided two pairs of holes 40 , whereas a hole 41 is provided in the wall 36 .
Finally, the device according to the invention is used with an adjustment element 42 which is made such that it can rest in an appropriate manner on a rail 4 - 5 with its lower portion, whereas the upper portion defines a stair-shaped profile and to this end has different steps 43 which are all provided at different heights.
The mounting of a canopy 1 by means of a mechanism according to the invention is very simple and as follows.
First of all, the rails 4 - 5 are fixed onto the edges 7 of the roof by means of the above-mentioned L-shaped sections 8 and the screws 9 , after a carriage 6 has been provided on each rail 4 - 5 .
Then, the clip 27 is shifted over the tooth 23 by means of the groove 29 , such that the curved lateral walls 32 - 33 of the groove 29 can pivot against the curved lateral walls 24 - 25 of the tooth 23 , and such that the bottom 34 of the groove 29 rests on the rib 26 of the tooth 23 in order to facilitate the pivoting of the clip 27 in relation to the tooth 23 .
At this moment, the canopy 1 can be placed on the clip 27 , such that the protrusions 44 - 45 of the protrusion 1 catch in the hooks 28 - 30 of the clip 27 ; next a screw 46 is screwed in a nut 47 through the hole . 41 of the clip 27 , such that the far end of the screw 46 rests against the wall 48 of the canopy 1 so as to press the canopy in the clip 27 .
It is clear that the center distance of the axes between the clips 27 preferably corresponds to the center distance of the axes between the rails 4 - 5 .
In particular cases, it is possible, however, to make the clips 27 larger, such that either of the two clips 27 will be fixed onto the rails . 4 - 5 in an asymmetrical manner. This characteristic will be preferred when the rails 4 - 5 cannot be fixed in the ideal place, because a roof awning or the like is present.
In order to optimize the distribution of energy on the canopy 1 , the clips 27 can be either made larger as described above, or they can be replaced by a continuous clip which is fixed to the two rails 4 - 5 .
In order to be able to screw the screw 46 in the nut 47 , said nut 47 is shifted in the duct 31 of the clip 27 , such that it performs an antirotation between the walls 35 - 36 - 37 and the ribs 38 - 39 at the height of the hole 41 provided in the wall 36 .
Next, the canopy 1 is made to pivot around the tooth 23 of the T-shaped clip 27 , which is made considerably easier thanks to the fact that the bottom. 34 of the groove 29 rests on the rib 26 of the tooth 23 , as well as by the curved lateral walls 32 - 33 and 24 - 25 of the groove 29 , of the tooth 23 respectively, until the wall 49 of the canopy 1 fits perfectly to the edge 7 of the roof of the trailer, the camper or the like 3 .
Then, the adjustment element 42 is mounted in a position between the wall 35 of the duct 31 of the clip 27 on the one hand, and the top side of the rail 4 - 5 on the other hand, such that the canopy 1 is fixed as mentioned above.
Finally, the clip 27 is clamped on the carriage 6 by means of screws 50 and nuts 51 , such that the adjustment element 42 is simultaneously clamped in the selection or predetermined position.
To this end, the nuts 51 are shifted in the ducts formed by the sides 12 - 13 of the omega-shaped section, by the protruding walls 14 - 15 , by the fixing edges 16 - 17 and by the ribs 18 - 20 and 19 - 21 which are directed towards one another; then, the screws 50 are pressed through the holes 40 of the clip 27 and through the corresponding holes 52 provided in the protruding walls 14 - 15 , into the nuts 51 .
It is clear that a device for fixing a collapsible canopy to a roof is obtained in this manner, which makes it possible to mount a collapsible canopy onto the roof of any trailer or of any camper whatsoever in a very simple manner, whereby the device according to the invention makes the canopy fit perfectly onto the roof edge of the above-mentioned camper, trailer or the like, which is made possible among others thanks to the fact that the adjusting element has two series of steps upon which the rear end of the clip can rest and can be held so as to make the canopy fit perfectly onto the roof edge.
The invention is by no means limited to the above-described embodiments represented in the accompanying drawings; on the contrary, such a device can be made in all sorts of variants while still remaining within the scope of the invention.
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A device for attaching a collapsible canopy having fittings to an exterior surface of a vehicle includes two elongated parallel rails mounted on the exterior surface in spaced apart parallel relation, two carriages each slidably mounted along a longitudinal axis on a respective rail, two clips each mounted on a respective carriage and arranged to cooperate with the canopy fittings and two adjustment elements each mounted along a respective rail and cooperating with respective clips and carriages. Each of the adjustment elements has an upper portion that defines a stair-shaped profile arranged to cooperate with the canopy fittings.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a Continuation-In-Part (CIP) of U.S. patent application Ser. No. 13/002,668 filed Feb. 3, 2011, which is a U.S. National Stage of PCT/AU2009/000756 filed Jun. 16, 2009 which, in turn, claims priority to Australian Application No.: 20080903531 filed Jul. 29, 2008, the entire contents of each which is incorporated herein by reference in their entireties.
FIELD OF THE INVENTION
The present invention relates to optical equipment and, in particular, to a marking device used by an ophthalmic surgeon to mark a patient's eye prior to, for example, intraocular surgery such as cataract surgery.
BACKGROUND ART
Cataract surgery has been performed for many years. Toric intraocular lenses have been available for many years (StarSurgical/Rayner) but recently Alcon has popularised their use. This lens is particularly useful for patients having astigmatism. Roughly one third of all patients requiring cataract surgery have astigmatism and in order for the intraocular lens to function correctly it must be accurately placed. It is estimated that for every degree of incorrect orientation, the astigmic correction factor for such an intraocular lens decreases by approximately 3%. As a consequence, pre-operative marking is imperative for accurate surgery.
However, measurements on the patient's eye which are conducted pre-operatively are conducted in the consulting rooms of the ophthalmic surgeon where the patient sits upright with his torso in a vertical position. However, when the patient lies down, and is thus supine as required for surgery, the eye rotates by a variable amount which differs considerably from patient to patient. Thus the intention of the marking procedure is to enable the eye to be marked with reference markings which can be used to determine the correct alignment of the intraocular lens, the correct alignment of incisions, etc., during surgery. The marks themselves are made with a dye that is painted onto or otherwise applied to various prongs of the marker and which are accurately pressed onto the eye whilst the patient is seated and thus has his head vertical.
There are three basic prior art marking devices. One class of such devices are free hand systems where the marking prongs are located at one end of an elongate stem or pencil like handle which is held by the ophthalmic surgeon. This relies upon the dexterity of the surgeon. There is another device which incorporates a small spirit level into the handle in order to indicate a horizontal plane. There is a third class of markers which incorporate a plumb bob and thus rely upon gravitational forces to maintain the marking device aligned with the vertical. It is with this class of marking devices that the present invention is concerned. The particular prior art device which gave rise to the present invention is manufactured by Rumex of St Petersburg, Fla., USA.
In U.S. Pat. No. 8,491,616 Davis an instrument is disclosed in which a weighted stem 60 is connected by a short handle 50 which the medical practitioner holds. As illustrated in FIG. 9 , the handle 50 is only long enough to be held in the fashion of a tea-cup handle between the thumb and forefinger of the operator. This is a relatively awkward and uncomfortable grip which does not assist in the production of accurate results.
In German Utility Model 20 2008 004 59301 a similar arrangement is disclosed with the handle 50 of Davis above being replaced with an axle 14 which is rotatably and transversely mounted at one end of an elongated handle 11 . Thus the handle of the medical practitioner is located on the handle 11 and thus positioned far away from the eye of the patient. As a consequence the fingers of the handle holding the handle can not be used to manipulate the patient's eyelids, if necessary.
Genesis of the Invention
The genesis of the present invention is a desire to improve the abovementioned Rumex prior art marking device.
SUMMARY OF THE INVENTION
In accordance with a first aspect of the present invention there is disclosed an ophthalmic marker for marking a patient's eyeball prior to intraocular surgery, said marker comprising a central longitudinal axle defining a longitudinal axis, said axle being contained within, and rotatable relative to, an elongate substantially co-axial and substantially cylindrical body constituting a handle able to be grasped in the manner of a pencil, one end of said axle extending beyond said body and terminating in an optical marker means, and the other end of said axle extending beyond said body and terminating in a plumb bob, said plumb bob being interconnected to said axle to apply a gravitational torque thereto.
In accordance with a second aspect of the present invention there is disclosed a method of making a marker to mark a patient's eyeball prior to intraocular surgery, said method comprising the steps of:
(i) locating at least two marker points one at each opposite end of a substantially U-shaped yoke, (ii) locating said yoke at one end of an axle, (iii) rotatably mounting said axle within a substantially co-axial hollow handle, the other end of said axle extending beyond said handle, and (iv) connecting a plumb bob to said handle to apply a gravitational torque thereto.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:
FIG. 1 is front elevational view of a patient's eye with the patient vertical and showing the desired location of three marks,
FIG. 2 is a horizontal cross-section to enlarged scale showing the patient's cornea and the marks A and B of FIG. 1 ,
FIG. 3 is a perspective view of a prior art ophthalmic marking device,
FIG. 4 is a perspective view of the ophthalmic marker of the preferred embodiment being held in the right hand of an ophthalmic surgeon,
FIG. 5 is a perspective view of the rear end of the ophthalmic marker of FIG. 4 , and
FIG. 6 is a perspective view looking towards this right of the U-shaped yoke of the ophthalmic marking device of FIG. 4 .
DETAILED DESCRIPTION
As seen in FIG. 1 , prior to carrying out ophthalmic surgery, the eye 2 is required to be marked in order to enable the ophthalmic surgeon to identify the centre (or axis or front) of the eye when the patient is upright. As seen in FIG. 1 three points are preferably marked which in relation to the globe of the earth are as follows:
A: is on the equator, but at 90° west of the Greenwich meridian, B: is also on the equator but 90° east of the Greenwich meridian, and C: is on the Greenwich meridian but a latitude corresponding to the South Atlantic.
The points A and B are also illustrated in FIG. 2 which is a cross-sectional view taken along the line A-B of FIG. 1 and thus passes through the centre of the cornea 4 .
The prior art marking device able to mark the points A and B (only) of FIG. 1 is illustrated in FIG. 3 . The prior art device 10 has a pencil like handle 11 having a knurled portion 12 which enables the handle 11 to be conveniently held like a pencil by the hand of the ophthalmic surgeon.
At the front of the device 10 is a U-shaped yoke 13 having two points 15 , 16 to which a dye can be applied and which when placed on the eyeball 3 create the marks A and B. The yoke 13 is connected to the handle 11 by means of a curved rod 17 which is rotatably mounted within the handle 11 . A plumb bob 18 having a rigid stem 19 and a sphere 20 , is rigidly connected to the rod 17 .
In operation the device 10 is held with the handle 11 in a substantially horizontal plane opposite the patient's eye 2 . The weight of the plumb bob 18 ensures that the rod 17 is rotated by the plumb bob 18 . Thus the plumb bob 18 is vertical and so the yoke 13 (which is perpendicular to the stem 19 ) is horizontal. Thus provided the ophthalmic surgeon keeps the handle 11 in a substantially horizontal plane, the ophthalmic surgeon can judge the centre (or axis or front) of the eye and then bring the points 15 and 16 into contact with the eyeball 3 and thereby make the marks A and B simultaneously and reasonably accurately.
This arrangement suffers from three difficulties. The first is that the ophthalmic surgeon must keep the handle 11 substantially horizontal in order to ensure that the rod 17 can rotate under the influence of the plumb bob 18 . In addition, the fingers of the ophthalmic surgeon are not able to be moved any further forwardly along the device 10 than the knurled portion 12 since the fingers must not interfere with the swinging operation of the plumb bob 18 . As a consequence, the ophthalmic surgeon has only his other hand with which to control the patient's eye lids and so this is generally of inconvenience to the ophthalmic surgeon. Thirdly, the plumb bob 18 must not come into contact with the patient lest its vertical position be disturbed, thereby moving the pointers 15 , 16 away from the horizontal.
Turning now to FIGS. 4 to 6 , the ophthalmic marker 30 of the preferred embodiment has an elongate handle 31 with a ribbed portion 32 constituting a finger grip. A U-shaped yoke 33 is provided but is orientated into the vertical plane and has three points 34 , 35 and 36 respectively which protrude perpendicularly from the plane of the yoke 33 . The yoke 33 is connected by means of a cranked portion 37 to an axle 42 which extends the length of the elongate handle 31 . The axle 42 is rotatably mounted relative to the elongate handle 31 so as to be substantially co-axial therewith and to be a smooth substantially frictionless rotational fit within the handle 31 .
As best seen in FIG. 5 , the rear end of the axle 42 is bifurcated at 44 and the rigid stem 39 of a plumb bob 38 (including a sphere 40 ) is pivoted by means of a pin 45 which extends through the bifurcated portion 44 of the axle 42 . As also seen in FIG. 5 , the axle 42 is supported by a bearing plate 47 and is conveniently visible through an aperture 49 in the handle 31 .
Since the axle 42 is rotatably mounted, the weight of the plumb bob 38 with its sphere 40 maintains the U-shaped yoke 33 with its points 35 and 36 uppermost and level (ie horizontal), irrespective of any twisting action of the handle 31 relative to the axle 42 . Thus no matter how the ophthalmic surgeon either deliberately or inadvertently rotates the elongate handle 31 relative to the axle 42 , the axle 42 always remains stationery with the stem 39 vertical and thus the points 35 and 36 horizontal.
Furthermore, the elongate handle 31 can be tilted in a vertical plane through a wide range of degrees and the plumb bob 38 remains vertical since the stem 39 is able to pivot about the pin 45 . Therefore it is not necessary for the ophthalmic surgeon to keep the handle 31 in a substantially horizontal plane as is the case with the handle 11 of the prior art device 10 .
As a consequence of these mechanical improvements, the marker 30 is much more convenient for the ophthalmic surgeon to use. In particular, the forefinger and middle finger of the hand holding the marker 30 are available to assist in maintaining the patient's eye lids retracted and steady the hand, if necessary, thereby enabling the ophthalmic surgeon to use more than one hand in carrying out the marking procedure.
In addition, the additional point 34 enables the mark C as illustrated in Fig . 1 to be made, thereby improving the definition of the optical axes for the surgeon.
Still further, the elongate handle 31 is able to be held by the surgeon in the same manner as one holds a new pencil or pen. This grip is comfortable and much more relaxed for the surgeon than the awkward tea-cup holder posture of Davis. As best seen in FIG. 4 , the length of the handle 31 extends from in front of the tip of the surgeon's thumb and forefinger to well behind the upper surface of the surgeon's hand (that is the surface of the hand opposite to the palm).
The foregoing describes only one embodiment of the present invention and modifications, obvious to those skilled in the ophthalmic arts, can be made thereto without departing from the scope of the present invention.
The term “comprising” (and its grammatical variations) as used herein is used in the inclusive sense of “including” or “having” and not in the exclusive sense of “consisting only of”.
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An ophthalmic marker having a U-shaped yoke ( 33 ) at one end of a cranked axle ( 42 ) is disclosed. The axle ( 42 ) is rotatable mounted with a co-axial cylindrical handle ( 31 ). The other end of the axle extends beyond the handle and is bifurcated. A plumb bob ( 38 ) having a sphere ( 40 ) and a stem ( 39 ) is pivotally mounted on the bifurcated end of the axle ( 42 ). The yoke ( 33 ) has three marker points ( 34 - 36 ) the upper two ( 35, 36 ) of which are maintained in a horizontal plane by a gravitational force urging the plumb bob ( 38 ) into a vertical plane notwithstanding the handle ( 31 ) not being held exactly horizontal. A method of eye marking and marker making are also disclosed.
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BACKGROUND OF THE INVENTION
This invention relates generally to integrated circuit packaging incorporating a high density interconnect structure, and more particularly to packaging high speed devices having sensitive structures such as air bridge structures, with a protective material, which after lamination of the high density interconnect structure can be removed without ablating a large area of the high density interconnect structure.
In the fabrication of certain multi-chip module (MCM) circuits, high performance is accomplished by the use of high speed gallium arsenide (GaAs) devices having delicate structures which can easily be damaged or destroyed during fabrication. These include conductors which are spaced from the surface of the GaAs by an air gap--a structure which is known as an air bridge. Air bridges are used in these circuits to provide improved signal propagation and reduced capacitive coupling over that possible with conventional chip wiring.
The interconnect structure used in the fabrication of high density interconnect (HDI) circuits has many advantages in the compact assembly of MCMs. For example, a multi-chip electronic system (such as a microcomputer incorporating 30-50 chips) can be fully assembled and interconnected by a suitable HDI structure on a single substrate, to form a unitary package which is 2 inches long by 2 inches wide by 0.050 inches thick. Even more important, the interconnect structure can be disassembled from the substrate for repair or replacement of a faulty component and then reassembled without significant risk to the good components incorporated within the system. This is particularly important where many (e.g., 50) chips, each being very costly, may be incorporated in a single system on one substrate. This repairability feature is a substantial advance over prior connection systems in which reworking the system to replace damaged components was either impossible or involved substantial risk to the good components.
Briefly, in this high density interconnect structure, a ceramic substrate such as alumina which may be 50-100 mils thick and of appropriate size and strength for the overall system, is provided. This size is typically less than 2 inches square, but may be made larger or smaller. Once the position of the various chips has been specified, individual cavities or one large cavity having appropriate depth at the intended locations of differing chips, is prepared. This may be done by starting with a bare substrate having a uniform thickness and the desired size. Conventional, ultrasonic or laser milling may be used to form the cavities in which the various chips and other components will be positioned. For many systems where it is desired to place chips nearly edge-to-edge, a single large cavity is satisfactory. That large cavity may typically have a uniform depth where the semiconductor chips have a substantially uniform thickness. The cavity bottom may be made respectively deeper or shallower at a location where a particularly thick or thin component will be placed, so that the upper surface of the corresponding component is in substantially the same plane as the upper surface of the rest of the components and the portion of the substrate which surrounds the cavity. The bottom of the cavity is then provided with a thermoplastic adhesive layer, which may preferably be a polyetherimide resin (such as ULTEM® 6000 resin, available from the General Electric Company, Fairfield, Conn.), or an adhesive composition such as is described in U.S. Pat. No. 5,270,371, herein incorporated in its entirety by reference. The various components are then placed in their desired locations within the cavity and the entire structure is heated to remove solvent and thermoplastically bond the individual components to the substrate.
Thereafter, a film (which may be KAPTON® polyimide, available from E. I. du Pont de Nemours Company, Wilmington, Del.), of a thickness of approximately 0.0005-0.003 inches (approx. 12.5-75 microns), is pretreated by reactive ion etching (RIE) to promote adhesion. The substrate and chips must then be coated with ULTEM® 1000 polyetherimide resin or another thermoplastic adhesive to adhere the KAPTON® resin film when it is laminated across the tops of the chips, any other components and the substrate. Application of the ULTEM® resin adhesive is an extra processing step that must be used if a thermoplastic adhesive is to hold the KAPTON® resin film in place. Thereafter, via holes are provided (preferably by laser drilling) through the KAPTON® resin film, and ULTEM® resin layers, at locations in alignment with the contact pads on the electronic components to which it is desired to make contact. A multi-sublayer metallization layer, with a first sublayer comprising titanium and a second layer comprising copper, is deposited over the KAPTON® resin layer and extends into the via holes to make electrical contact to the contact pads disposed thereunder. This metallization layer may be patterned to form individual conductors during the deposition process or may be deposited as a continuous layer and then patterned using photoresist and etching. The photoresist is preferably exposed using a laser to provide an accurately aligned conductor pattern at the end of the process. Alternatively, exposure through a mask may be used.
Additional dielectric and metallization layers are provided as required in order to provide all of the desired electrical connections among the chips. Any misposition of the individual electronic components and their contact pads is compensated for by an adaptive laser lithography system which is the subject of some of the patents and applications listed hereinafter.
This high density interconnect structure provides many advantages. Included among these are the lightest weight and smallest volume packaging of such an electronic system presently available. A further, and possibly more significant, advantage of this high density interconnect structure, is the short time required to design and fabricate a system using this high density interconnect structure. Prior art processes require the prepackaging of each semiconductor chip, the design of a multilayer circuit board to interconnect the various packaged chips, and so forth. Multilayer circuit boards are expensive and require substantial lead time for their fabrication. In contrast, the only thing which must be specially pre-fabricated for the HDI system is the substrate on which the individual semiconductor chips will be mounted. This substrate is a standard stock item, other than the requirement that the substrate have appropriate cavities therein for the placement of the semiconductor chips so that the interconnect surface of the various chips and the substrate will be in a single plane. In the HDI process, the required cavities may be formed in an already fired ceramic substrate by conventional or laser milling. This process is straight-forward and fairly rapid with the result that once a desired configuration of the substrate has been established, a corresponding physical substrate can be made ready for the mounting of the semiconductor chips in as little as 1 day and typically 4 hours for small quantities as are suitable for research or prototype systems to confirm the design prior to quantity production.
The process of designing an interconnection pattern for interconnecting all of the chips and components of an electronic system on a single high density interconnect substrate normally takes somewhere between one week and five weeks. Once that interconnect structure has been defined, assembly of the system on the substrate and the overlay structure is built-up on top of the chips and substrate, one layer at a time. This process can be finished in as little as four hours, as described in U.S. Pat. No. 5,214,655, entitled "Integrated Circuit Packaging Configuration for Rapid Customized Design and Unique test Capability" by C. W. Eichelberger, et al., herein incorporated in its entirety by reference. Consequently, this high density interconnect structure not only results in a substantially lighter weight and more compact package for an electronic system, but enables a prototype of the system to be fabricated and tested in a much shorter time than is required with other packaging techniques.
This high density interconnect structure, methods of fabricating it and tools for fabricating it are disclosed in U.S. Pat. No. 4,783,695, entitled "Multichip Integrated Circuit Packaging Configuration and Method" by C. W. Eichelberger, et al.; U.S. Pat. No. 5,127,998, entitled "Area-Selective Metallization Process" by H. S. Cole et al.; U.S. Pat. No. 5,127,844, entitled "Area-Selective Metallization Process" by H. S. Cole, et al.; U.S. Pat. No. 5,169,678, entitled "Locally Orientation Specific Routing System" by T. R. Haller, et al.; and U.S. Pat. No. 5,108,825, entitled "An Epoxy/Polyimide Copolymer Blend Dielectric and Layered Circuits Incorporating It" by C. W. Eichelberger, et al; U.S. application Ser. No. 07/987,849, entitled "Plasticized Polyetherimide Adhesive Composition and Usage" by Lupinski et al. Each of these Patents and Patent Applications, including the references contained therein, is hereby incorporated in its entirety by reference.
This high density interconnect structure has been developed for use in interconnecting semiconductor chips to form digital systems. That is, for the connection of systems whose operating frequencies are typically less than about 50 MHz, which is low enough that transmission line, other wave impedance matching and dielectric loading effects have not needed to be considered.
The interconnection of structures or devices intended to operate at very high frequencies presents many challenges not faced in the interconnection of digital systems. For example, use of gigahertz frequencies requires consideration of wave characteristics, transmission line effects and material properties. Also, use of high frequencies requires the consideration of the presence of exposed delicate structures on MCMs and other components and system and component characteristics which do not exist at the lower operating frequencies of such digital systems. These considerations include the question of whether the dielectric materials are suitable for use at gigahertz frequencies, since materials which are good dielectrics at lower frequencies can be quite lossy or even conductive at high frequencies. Further, even if the dielectric is not lossy at gigahertz frequencies, its dielectric constant itself may be high enough to unacceptably modify the operating characteristics of MCMs or air bridges.
As stated above, the interconnect structure used in the fabrication of HDI circuits is created from alternating layers of laminated dielectric films and patterned metal film. In the process of laminating the dielectric layers, the adhesive used to bond the dielectric layers is caused to flow and form a quality, void-free interface. There is a substantial concern that air bridges and other sensitive structures may be modified, damaged or destroyed by the lamination pressure. Also, these sensitive structures may be overlay sensitive, i.e., the operating characteristics of the device or component may be different when the device or component is free of interconnection dielectric material than when these devices have high density interconnect dielectric layers disposed over them. Lamination as well as other processing steps may also cause the thermoplastic adhesive to infiltrate the air gap under the conductor, thereby modifying the dielectric properties of that gap.
Since there are sensitive structures present, low temperature processing is needed to ensure that these structures are not damaged during multi-chip module fabrication. For example, chips of certain semiconductors (GaAs, InSb and HgCdTe), as well as the structures on these chips, e.g., air bridges, are very sensitive to processing in high temperature regimes. For fabrication of multichip modules incorporating these chips, a high density interconnect structure is required with processing temperatures below 260° C.
To maintain the performance advantage of having air, or some other electrical insulator, as the dielectric medium, the MCM fabrication process must be designed to provide a means of preserving these air bridge structures from intrusion by other materials.
For example, related application Ser. No. 07/869,090 filed on Apr. 14, 1992, by W. P. Kornrumpf et al., and entitled, "High Density Interconnected Microwave Circuit Assembly" teaches removing the high density interconnect dielectric from portions of the chip which are overlay sensitive. That is, after the HDI structure is laminated, the portion of the HDI structure overlying the sensitive structure is removed by ablation. Removing the HDI structure improves the performance of the sensitive structure, e.g., air bridge, because there is no overlying material. However, ablating the overlying material does not prevent adhesive from flowing under the bridge during processing; nor does it prevent the lamination pressure from occasionally damaging or even collapsing the air bridge. As will be discussed hereinbelow, removing the HDI structure over the sensitive structure also decreases the area available for routing the electrical conductors within the HDI structure and severely restricts the potential usefulness of the HDI technique. This patent application, including the references contained therein, is hereby incorporated in its entirety by reference.
Related U.S. Pat. No. 5,331,203, filed Apr. 5, 1990, by Wojnarowski et al., and entitled "A High Density Interconnect Structure Including a Chamber" teaches bonding the chip containing a sensitive structure into a deep chip-well. Since the chip-well is deeper than the chip is thick, there is a space created over the surface of the chip. A first dielectric layer is laminated such that this layer is only attached to a plateau portion of the substrate and to the upper surface of the chip. This first dielectric layer is not applied over the sensitive structure. Then, the remainder of the HDI structure is laminated, thereby creating a "chamber" of air over the sensitive structure. If successfully laminated, this technique creates a space over the sensitive structure to allow it to work properly. However, in practice this lamination procedure is very difficult to reproduce without damaging the sensitive structure. Because the second dielectric layer has adhesive, it is still difficult to produce a module where the adhesive from this layer does not infiltrate the space under the air bridge. Furthermore, because the chip is in a deep chip-well it is difficult to make electrical contact with the chip pads through the via holes with the metallization layer within the high density interconnect structure. This patent application, including the references contained therein, is hereby incorporated in its entirety by reference.
Related application Ser. No. 07/546,965, filed July 2, 1990, by Cole et al, and entitled "High Density Interconnection Including a Spacer and a Gap", teaches applying spacers over the contact pads present on the integrated circuit chips, and then stretching the first HDI dielectric layer over these spacers such that the dielectric layer does not contact the chip surface. This application provides a method of fabricating a HDI module incorporating a sensitive chip structure without the dielectric layer of the high density interconnect structure inhibiting the chip's performance. However, since the adhesive from the first dielectric layer is designed to flow and form a void free layer, it may contaminate any sensitive structure which is placed between the spacers. Also, because the high density interconnect structure is supported only by the spacers, there may be difficulties with the dielectric layers sagging and causing interruptions in the metallization layers. This patent application, including the references contained therein, is hereby incorporated in its entirety by reference.
Related application Ser. No. 08/046,299, entitled "High Density Interconnection of Substrates and Integrated Circuit Chips containing Sensitive Structures", to Cole et al. teaches laying down a solvent soluble layer to "protect" the air bridge during lamination of the HDI structure. Once the module is fully worked-up, the HDI structure which overlays the sensitive structure is ablated away and the module is immersed in a solvent to remove the protective layer. This method, although very labor intensive, inhibits damage to the air bridge and prohibits the adhesive from getting under the bridge during lamination of the high density interconnect structure. This patent application, including the references contained therein, is hereby incorporated in its entirety by reference.
Unfortunately, the teaching disclosed in the last-mentioned application suffers from the disadvantage that the need to exclude the high density interconnect structure from the surface of overlay-sensitive components severely restricts the surface area available for the routing of the high density interconnect structure metallization layers since they cannot be routed over the area from which the dielectric layer is to be removed. Where chips are closely packed for maximum density, this essentially limits the high density interconnect structure to the routing of conductors in the "streets" and "avenues" portion of the structure which extends from the contact pads of one chip to the contact pads of the adjacent chip. For systems where high density of interconnect conductors is required, such a restriction can require excessive numbers of layers of interconnect conductors, require that the chips be spaced further apart than would otherwise be necessary, or even make a system unroutable.
Consequently, an improved method for protecting sensitive structures which does not disrupt the routing of the metallization layers within the high density interconnect structure, is desirable.
OBJECTS OF THE INVENTION
Accordingly, a primary object of the invention is to provide multi-chip modules fabricated with clean air bridges in a manner which does not sacrifice any metallization routing area in an overlying high density interconnect structure.
SUMMARY OF THE INVENTION
Briefly, according to the invention, a method for preserving an air bridge structure on an integrated circuit chip having chip pads includes the step of applying a sublimable protective layer over the air bridge. The protective layer can be applied solely to the air bridge, or applied to the entire substrate surface with the material then removed at areas other than those over the air bridge. A high density interconnect structure is applied over the chip and substrate with metallization layers interconnected to the chip pads. The protective layer provides mechanical strength during the application of the high density interconnect structure to prevent deformation during processing. It also prevents any contamination from intruding under the air bridge. A small portion of the high density interconnect structure is removed from the area over the air bridge structure, and the protective layer is then sublimed away to leave a multi-chip module with an undamaged air bridge which is free of residue.
BRIEF DESCRIPTION OF THE DRAWINGS
The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings in which:
FIGS. 1(a)-(d) are cross-sectional views of a multi-chip module at various progressive stages of a procedure for using a protective layer to provide mechanical support for an air bridge structure in micro-electronic circuitry;
FIG. 2 is a cross-sectional view of a chip with an air bridge structure encapsulated with a protective layer to provide mechanical support on all sides during processing.
DETAILED DESCRIPTION
Referring initially to FIG. 1(a), a multichip module 10 has a substrate 11 with a plurality of chip cavities 11a formed therein, through a top surface 11b thereof. An integrated circuit chip 12 or another electronic component is disposed in each chipwell 11a. Electronic components 12 may be bonded to the substrate 11 with a layer of a thermoplastic adhesive 14; these electronic components 12 have contact pads 12a on an upper contact surface 12b thereof. These electronic components 12 also have sensitive structures, such as air bridges 12c, on upper surface 12b.
In accordance with the invention, a protective layer 16 is applied over and around the sensitive structure 12c creating an encapsulating volume 16v, as shown in FIG. 2. This encapsulating volume 16v includes the area comprising the protective layer 16 as defined by a top surface 16a, sides 16b and a bottom 12c, as well as the area 16c underneath the air bridge which is essentially filled with protective layer 16. This encapsulation volume 16v has (1) a lower surface defined by the substrate surface plane, or the chip surface 12c, (2) an upper surface 16a spaced a distance above said sensitive structure (approximately less than 4 times the sensitive structure's height), and (3) walls 16b which generally extend from the lower surface to the upper surface.
This protective layer 16 supports the sensitive structure from all sides, and may be applied by masking the entire surface of the substrate surface 11b except the sensitive structure 12c, such that the protective layer 16 is only applied to the sensitive structure 12c. Alternatively, the entire substrate surface 11b may be coated with the protective layer 16 and then the protective layer 16 can be ablated away everywhere except over the sensitive structure 12c.
The protective layer 16 is preferably an organic monomer. This organic monomer 16 is applied to the substrate surface 11b through sublimation by conventional vacuum processes. The thickness of the sublimed monomer 16 is controlled by time, temperature and pressure during the deposition process. The organic monomer preferably has a sufficient vapor pressure (about 10 torr) at temperatures of about 170° C. to allow the material to be sublimed on to the chip surface 12b. These monomers also preferably have a melting point in excess of the processing temperature they will be exposed to, which in this case can be as high as about 260° C. This ensures that the protective layer will have sufficient mechanical integrity during the lamination sequence of the first dielectric layer and thus prevent the sensitive structures (air bridges) from being crushed or deformed. Several commercially available chemicals, such as those found in the Aldrich Chemical Catalog or Eastman Organic Chemicals Catalog, including naphthalene and anthraquinone derivatives can be utilized. Presently preferred materials include perylene, anthraquinone, alizarin and quinalizarin (all with melting points above 275° C.), with alizarin being the most preferred at this time. Additional organic monomers that meet the melting point and sublimation criteria can be found in the Handbook of Physics and Chemistry. Any high melting pint material that can be sublimed at about 170° C. will work in this invention, although it should be understood that monomers with extremely low vapor pressure will require longer vacuum baking to remove all of the material after module processing than monomers with higher vapor pressures.
The final structure of a high density interconnect structure 17 fabricated above the chips 12 (and the sensitive structures 12c) on the substrate upper surface 11b is shown in FIG. 1(b). A first stratum 18 of the overlying high density interconnect structure 17 comprises a dielectric layer 20 supporting a patterned metallization layer 22. The dielectric layer 20 has separate lower and upper sublayers 24 and 26, respectively, and supports the patterned metallization layer 22 which extends into contact with contact pads 12a on the substrate 11 within via holes 27 in the dielectric layer. The lower dielectric sublayer 24 is a thermoplastic adhesive which can be processed at temperatures below 260° C. As referenced hereinabove, U.S. application Ser. No. 07/987,849, teaches a plasticized polyetherimide adhesive, such as "Ultem"/"Benzoflex" (Ultem is a trademark of General Electric Co, Pittsfield, Mass., for a polyetherimide resin, and Benzoflex is a trademark of Velsicol Chemical Corp., Rosemont, Ill., or pentaerythritol tetrabenzoate). The upper dielectric sublayer 26 is preferably a thermoset material (for example, a KAPTON® film). Other materials, including thermoplastics which exhibit sufficient stability, may also be used for the upper dielectric sublayer 26.
A second stratum 28 of the high density interconnect structure comprises a second dielectric layer 30 supporting a second patterned metallization layer 32. The dielectric layer 30 has separate lower and upper sublayers 34 and 36, respectively. The second lower sublayer 34 is may be a siloxane polyimide/epoxy (SPIE) adhesive system as described in commonly assigned U.S. Pat. No. 5,161,093, issued Nov. 3, 1992, to Gorczyca et al, which is herein incorporated by reference in its entirety. Since this second dielectric layer is a SPIE thermosetting copolymer, and therefore changes its glass transition temperature value upon curing, laminating multiple layers does not affect lower layers. Via holes 37 are drilled and another patterned metallization sublayer 32 extends into via holes 37 in the dielectric layer 30 to make contact with the first metallization layer 22. If desired, selected via holes may extend through the first dielectric layer 20 as well to provide direct contact to selected contact pads 12a.
The third stratum 40 of the high density interconnect structure comprises a third dielectric layer 42 supporting a third patterned metallization layer 44. The dielectric layer 42 has separate lower and upper sublayers 46 and 48, respectively. The third lower dielectric sublayer is preferably a siloxane polyimide/epoxy (SPIE) adhesive. The third stratum also comprises a third patterned metallization layer 44. The third upper dielectric sublayer 48 may again be a thermoset material or a thermoplastic material and is preferably a thermoset material, i.e., KAPTON® film. Lamination of this third stratum 40 is followed by via drilling which extends vias 49 through the stratum 40 such that the patterned metallization layer 44 will connect to the metal layer 32 of the second dielectric layer 28.
Additional (fourth, fifth, sixth, etc.) strata of the high density interconnect structure 17 are not shown in FIG. 1(b), but, if used, will be essentially identical to the lower strata 18, 28 and 40. Each additional upper stratum would comprise a dielectric layer having a thermosetting adhesive (preferably a SPIE blend) and having via holes therein, and a patterned metallization layer making contact with the patterned metallization of the next lower patterned metallization layer through the via holes. Other strata can be added in accordance with the above description.
In this structure, the SPIE crosslinking copolymer blend adhesive materials used as the lower dielectric sublayer in the second and higher strata are selected so that these adhesive materials become set at a low enough temperature that curing the adhesive materials has no adverse effect on the high density interconnect structure or the electronic components being connected thereby. Correct selection of the curing properties of the adhesive materials allows the structure to be fabricated and, if need be, disassembled and reassembled without an adverse effect on the electronic components being interconnected.
After the high density interconnect structure 17 is complete, a channel 50 can be created in the high density interconnect structure 17 by removing a portion of the high density structure stretching form the encapsulating volume (not labeled) to the module surface, as shown in FIG. 1(c). This channel will expose the protective layer 16. The channel is preferably created by laser ablating the high density interconnect structure. The dielectric layers of the high density interconnect structure 17 of the present invention must therefore be laser ablatable or should be rendered laser ablatable in accordance with U.S. patent application Ser. No. 456,421, entitled, "Laser Ablatable Polymer Dielectrics and Methods," herein incorporated by reference in its entirety. The channel 50 may be smaller than the area covered by the protective polymer 16. It is desirable that the entire region covering the air bridge 12c not be removed in order to allow additional room in the high density interconnect structure 17 for routing of the metallization layers (22, 32, 44, etc.). Preferably, the channel 50 is less than 50 percent of the size of the encapsulating volume.
The protective material 16 can be removed from the volume encapsulating the air bridge 12c by heating the module to a temperature, and pulling a vacuum, sufficient to sublime the monomer. The temperature and pressure sufficient to sublime the illustrative alizarin monomer is approximately 170° C. and 0.01 torr, respectively. Due to the low vacuum environment, the sublimated material will be removed from the high density interconnect structure and pumped away, leaving the air bridge free from any contamination, as shown in FIG. 1(d).
At this point the fabricated module may be complete; various metallization layers 22, 32, 44 will carry power, ground, and at least one set of signal conductors. And since only a small portion of the high density interconnect structure is removed, there are little or no limitations on how the metallization layers must be routed.
EXAMPLES
The following illustrative examples are not intended to limit the scope of this invention but to illustrate its application and use:
Example 1
A vacuum sublimation apparatus was set up and various organic molecules were evaluated as candidate materials for this application. Molecules such as perylene, anthraquinone and alizarin (an anthraquinone derivative) were successfully sublimed onto silicon. The silicon chips were mounted on the cold plate of the sublimation apparatus using masking tape. The organic monomers were deposited as polycrystalline layers with reasonable adhesion. Films as thick as 25 microns were sublimed. The silicon chips were masked using standard masking tape for this experiment. After coating, the parts were removed and placed back in a vacuum oven to determine what heat and vacuum conditions would be needed to remove the molecule. In all instances, the monomers are sublimed off the silicon at temperatures in the range of 165° C. and pressures of about 0.01 torr.
Example 2
A chip was coated with 25 microns of alizarin and was placed on an alumina substrate using epoxy die attach techniques. "Kapton" polyimide film was then laminated over the part using an "Ultem" polyetherimide/"Benzoflex" pentaerythritol tetrabenzoate adhesive mixture at 260° C. Three via holes (500×500 microns in size) were laser drilled through this film/adhesive layer to provide an opening that the alizarin could be sublimed through. A roughing pump and liquid nitrogen trap were used with a vacuum oven set at 170° C. The sample was placed in the vacuum oven overnight, removed and inspected. It was observed that the alizarin underneath the laminant layer had been substantially removed from the chip surface in the regions of the via holes, extending in excess of 500 microns in all directions from the via holes.
While the invention has been described in detail herein in accordance with certain preferred embodiments thereof, many modifications and changes therein may be effected by those skilled in the art. Accordingly, it is our intent to be limited only by the scope of the appending claims and not by way of the details and instrumentalities describing the embodiments shown herein.
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In a method for preserving an air bridge structure on an integrated circuit chip, without sacrificing metallization routing area in an overlying high density interconnect structure, a protective layer is sublimed over the air bridge to provide mechanical strength while preventing contamination and deformation during processing. A high density interconnect structure is applied over the chip and protective layer. A small portion of the high density interconnect structure is removed from the area over the air bridge structure, and the protective layer is then sublimed away, leaving the resultant structure with an undamaged air bridge which is free of residue.
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BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to semiconductor devices. More particularly, the present invention relates to methods of making and the structure of trench capacitors in memory devices.
[0003] 2. Background Information
[0004] The semiconductor industry requires miniaturization of individual devices such as transistors and capacitors to accommodate the increasing density of circuits necessary for semiconductor products. One common semiconductor product is a dynamic random access memory (“DRAM”), which may incorporate billions of individual DRAM memory units (cells), each capable of storing one data bit. A DRAM cell includes a planar access transistor and a storage capacitor. The access transistor transfers charge to and from the storage capacitor to read or write data. The total amount of charge stored in the capacitor must exceed a threshold value, which is based on the minimum amount of charge required to read the capacitor by a sensing device, and the frequency at which the capacitors are re-charged (refreshed). Because the capacitors do not retain their charge for an infinite time, periodic capacitor refreshing is required to replace leaking charge before the total charge retained falls below the value needed to read a memory cell.
[0005] In order to increase the memory capacity on a chip, i.e., the number of cells, there is a need to shrink the amount of horizontal area on the chip used by each cell, which requires a reduction in transistor and/or capacitor size. However, as the total cell size is reduced, the amount of charge retained in a horizontal planar capacitor may not be sufficient to ensure proper device operation, since the capacitance is directly proportional to the planar area of the device. One technique to address this problem is to fabricate trench capacitors, which have a trench shape when viewed in cross section and are formed by vertical etching into the silicon substrate, typically using gaseous species. FIG. 1a shows an the ideal trench capacitor 1 , where insulator 8 has a U-shape and is bounded on the outside by an outer capacitor electrode (plate) 2 , and on the inside by an inner plate 7 . Plate 2 represents the ‘bottom’ plate formed by doping the silicon substrate and contains surfaces 3 , 3 ′, and 4 , with dimensions, d1, d2, and w1, respectively. In a cylindrical trench, surfaces 3 and 3 ′ are part of the same cylinder wall. Similarly, the “top” plate 7 has vertical surfaces 6 , 6 ′, and horizontal surface 5 , which are approximately the same dimensions as bottom plate surfaces, 3 , 3 ′, and 4 , respectively.
[0006] In terms of behavior and size, it is well known to those skilled in the art that the ideal trench capacitor of FIG. 1a can be approximated by an equivalent planar capacitor shown in FIG. 1 b , containing plates 11 , 13 and insulator 12 , whose width W equals the sum of d1, d2, and w1. In current technology, a trench typically has a depth in the range of 4-8 μm and an oval or rounded top-down-view shape, with a horizontal dimension which may be less than 0.5 μm. Referring to FIGS. 1 a and 1 b , and assuming the same insulator thickness, a trench capacitor of 0.5 um width (w1) and 4 um depth (d1) has the approximate capacitance of a planar capacitor of 8.5 um width. That is, the trench capacitor is equivalent to a planar capacitor whose width W is the sum of the trench capacitor width and two times its depth. Thus, the trench capacitor structure permits a large capacitance per planar unit area of substrate, while at the same time allowing the device cell to occupy a small portion of the cell area.
[0007] For a given DRAM cell size, where the size of the horizontal trench opening is fixed, the capacitance in a trench capacitor can be increased simply by increasing the trench depth. However, it is also well known to those skilled in the art that the vertical etch that is used to form the trench typically results in a tapered trench profile, which produces a smaller surface area and therefore lower capacitance than if the trench formed an ideal cylindrical shape. FIG. 2 shows “vertical” walls 21 , 21 ′, and trench bottom 22 . The walls taper in during etch, causing the bottom of the trench to taper toward a point. The tapering is due in part to the increased ratio of depth to width in the trenches as they are etched deeper, which reduces the ability of the gaseous etching species impinging from outside the trench to strike the outer portions of the trench bottom. Thus, for a given planar hole diameter, there is a limit to the trench depth that is attainable, since the trench walls taper in towards a point.
[0008] Related art teaches methods of forming better trench capacitor geometries, such as the “deep trench bottle etch (BE) process”. FIG. 3 illustrates the appearance of a trench formed using the BE process. The BE process includes formation of an insulating collar 25 , inside the top of the silicon trench after initial deep trench etch which is used to form surfaces 3 , 3 ′, and 4 , shown as a dashed line. This is followed by a liquid chemical etch, which removes the silicon residing underneath the collar in the lower part of the trench, and results in a bottle-shaped final profile of the trench. The etch tends to be isotropic; that is, the silicon at the surface of vertical and horizontal portions of the trench is etched at about the same rate. FIG. 3 shows that the final trench contains vertical surfaces 26 , 26 ′, and horizontal surface 27 , all larger than their original counterparts 3 , 3 ′, and 4 , respectively. In addition, new surfaces 28 and 28 ′ are formed at the top of the trench, adding to the overall surface area. In this manner, the area of the trench capacitor is made larger by increasing both the depth and the width of the trench.
[0009] It will be appreciated by those skilled in the art that care must be employed to form bottle-shaped trenches using a wet chemical etch in the manner described above. The uniformity of such etches depends on many variables, such as the concentration of active etching species in the liquid etchant, which can vary over time, causing the silicon removal in the lower trench to increase or decrease. Additionally, control of the effective time that the trench is exposed to liquid etchant may be difficult. The etch time employed to form the bottle trench is based on the known etch rate of silicon when subject to a given concentration of etchant. After the desired etch time, wafers containing the DRAM chips are rinsed and dried to dilute, and then remove, the etchant from the bottle trenches and prevent further etching of silicon. However, the extremely small size and bottle shape of the trenches can act to retard liquid etchant removal, resulting in an effective etch time greater than desired. In addition, the etch profile within a trench may not be uniform, due to incomplete or tardy removal of liquid etchant in certain regions such as corners in the trench. For the above reasons, among others, the uniformity of trench size may be difficult to control, and can lead to failures where adjacent bottle trenches merge, as depicted in FIG. 4 . FIG. 4 illustrates an array of equally-spaced bottle trenches 31 , 32 , 33 , and 34 after bottle etch and rinse. The profiles are sketched to illustrate less-than ideal final trench shapes that may form for the reasons mentioned above. While the internal surfaces 43 and 44 of trenches 33 and 34 , respectively, remain distinct, surfaces 41 and 42 of trenches 31 and 32 , respectively, have merged leading to a storage failure in the corresponding memory cells.
[0010] A further problem with the bottle etch process described in related art is that the nonunifomity can lead to significantly lower than ideal trench capacitance. In order to reduce the risk of merging of trenches that is inherent in the process, a maximum tolerable trench width can be established, based on the separation distance of adjacent trenches. Then, a nominal bottle etch process recipe is developed to allow for variations in the bottle etch process. FIGS. 5 a - c illustrate examples of three different chemical etch conditions applied to form a bottle trench after an initial vertical etch. FIG. 5 a shows a group of trenches after chemical etch for the nominal process conditions, which results in trench 51 of width d5. This is the result that obtains when the etch time, etchant concentration, and rinse are all carried out exactly according to the designed etch recipe. The trenches in FIG. 5 b illustrate the result of trench formation using the minimal tolerable chemical etch condition, which may denote the state where the effective etch time deviates below the nominal time by the greatest allowable amount; and the actual etchant concentration is less than the nominal by the maximum tolerable amount. The resulting trench 52 has width d6, which is less than d5. The converse of FIG. 5 b is shown in FIG. 5 c , where the trenches have been etched to the maximum size, width d7, where the effective etch time and concentration exceed the nominal values by the maximum tolerable amount. The value of d7 minus d6 (V) represents the variability in trench size resulting from the chemical etch process, which may be on the order of tenths of micrometers. The nominal trench size d5, must be smaller than d7 by a value that may be about V/2. Thus, the average capacitor will have a significantly smaller dimension (with concomitantly lower capacitance) than the maximum size capacitor.
[0011] A further result of a large variability in the chemical etch process is the production of many trenches with significantly lower capacitance (or size) than nominal, as illustrated by the capacitor structures shown in FIG. 5 b.
[0012] In view of the foregoing, it can be appreciated that a substantial need exists for improvement of trench storage capacitors.
SUMMARY OF THE INVENTION
[0013] The present invention relates to structures and processes that improve storage capacitors. In particular, a process is disclosed that overcomes present limitations on production of trench capacitors. An exemplary embodiment of the current invention comprises a bottle trench capacitor structure formed by selective removal of a uniform sacrificial silicon layer of pre-determined thickness from the lower part of the trench. An object of the present invention is to produce bottle trench capacitors in a manner such that the risk of merging adjacent trenches during processing is minimized. This is accomplished in an exemplary embodiment of the current invention by use of a selective chemical etch with a built-in electrochemical etch stop. A bilayer region of silicon in the trench structure is formed such that the surface layer is removed under electrochemical etch without removal of the bottom layer. In this manner the amount of silicon removed from the trenches can be limited, and the problem of merging of adjacent trenches is avoided.
[0014] A further aspect of the present invention relates to the production of trenches of uniform size, such that the capacitance variation between trench devices is minimized. It is well known to those skilled in the art that, in addition to variation in dielectric layer thickness, the primary influence on trench capacitance is the internal trench surface area, which is, in turn, directly proportional to the trench size. In exemplary embodiments of the current invention, the final trench size is in large part determined by removal of a sacrificial silicon layer of well-controlled thickness as detailed below. This results in capacitors of more uniform dimension compared to those produced by conventional processes. An additional object of the current invention is the fabrication of trenches with maximum capacitance attainable for a given DRAM cell size and trench separation. It will be appreciated by those skilled in the art that the more uniform process contained in embodiments of the present invention makes it possible to increase the average trench width without increased risk of failure due to merging of trenches.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIGS. 1 a and 1 b represent, respectively, an ideal trench capacitor in cross-section, and its planar capacitor equivalent.
[0016] FIG. 2 is a cross section representing realistic trench profiles achieved using standard vertical etch processes.
[0017] FIG. 3 is a drawing illustrating a bottle trench formed by a wet chemical etch employed after a standard vertical etch step according to known art.
[0018] FIG. 4 is a drawing illustrating bottle trench non-uniformities and failure due to wet chemical etch process variation.
[0019] FIGS. 5 a - c are schematic drawings illustrating the impact of wet chemical etch process non-uniformity on average dimension of bottle trenches.
[0020] FIGS. 6 a - d are drawings illustrating bottle trench formation according to an embodiment of the present invention.
[0021] FIG. 7 illustrates details of electrochemical etch processing steps according to an embodiment of the present invention.
[0022] FIG. 8 is a drawing illustrating an electrochemical etch apparatus according to another embodiment of the current invention.
[0023] FIG. 9 illustrates a current-voltage passivation curve for n-type silicon.
DETAILED DESCRIPTION OF THE INVENTION
[0024] Preferred embodiments of the present invention are described below, with reference made to the enclosed drawings. Before one or more embodiments of the invention are described in detail, one skilled in the art will appreciate that the invention is not limited in its application to the details of trench structure and the arrangement of steps set forth in the following detailed description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.
[0025] The present invention is related to methods and structures for providing large and uniform DRAM trench capacitors. Current methods of bottle trench capacitor fabrication employ non-selective wet etching of silicon to enlarge the trench below a collar region. This process entails the risk of complete silicon removal between trenches (“trench merge”, as shown in FIG. 4 ) if the etch process is not terminated in a timely fashion. According to an embodiment of the present invention, a selective etch process is employed to form the bottle trench that substantially eliminates the etch variability seen in the related art. Exemplary embodiments are now described in relation to FIGS. 6-10 .
[0026] In FIG. 6 a , after standard deep trench formation using well known techniques, an insulating collar 60 is fabricated so that it lines the top part of the trench. In an exemplary embodiment, the collar is formed by depositing a photoresist material to line the bottom of the trench, followed by growth of an oxide on the inside surface near the top of the trench. In some embodiments this collar may comprise a nitride, or related material that is resistant to a subsequent bottle etch. After oxide collar formation, the resist in the lower region of the trench is chemically stripped while leaving the oxide collar untouched. In the lower part of the trench the silicon is thus unprotected, forming surface 61 . The adjacent vertical walls of neighboring trenches are separated by distance l i . After insulating collar formation, an n-type dopant is introduced into the silicon in the lower trench, forming region 62 , as illustrated in FIG. 6 b . In an exemplary embodiment, this is accomplished by gas-phase doping methods well-known to those skilled in the art. The depth of the n-type doping, t n , is defined (with reference to FIG. 6 b ) by the vertical distance between the bottom of the trench and the bottom of the n-doped silicon layer, border 63 . This depth extends equally from all trench surfaces, and is preferably large enough so that the n-doped silicon region extends entirely between adjacent trenches, as depicted in FIG. 6 b . In a preferred embodiment, the doping level is about 1-5E18 cm −3 . Subsequently, as illustrated in FIG. 6 c , a p-type dopant is introduced to the trench region, extending to a depth t p , less than that of the n-type region. The concentration of p-type dopant exceeds that of the n-type dopant previously introduced, resulting in a distinct p-type silicon layer 64 extending from the trench surface to a boundary 65 with the n-type layer, as shown in FIG. 6 c . After p-type layer formation, the dual-doped trench structure contains regions 62 and 64 which are comprised of activated dopants creating a p-n junction at interface 65 . Although not essential to the current invention, it will be appreciated by skilled artisans that the horizontal width of the p-type layer may be substantially equivalent to the vertical depth, t p , as defined above. FIG. 6 c further shows that, in an exemplary embodiment, a region of n-type silicon 66 remains between the vertical portion of p-type layers in adjacent trenches. Thus, in an exemplary embodiment of the current invention, t p is typically less than half of L i , the spacing between the vertical edges of neighboring trenches. In a preferred embodiment, the level of p-type doping is in the range of 1 E19 cm −3 or higher, rendering the layer a “p+” silicon region. It is also to be appreciated that the gas phase doping process allows the growth of layers of highly uniform thickness when compared to the trench dimensions. That is, while overall trench width may be in the range of 100-1000 nm, the expected variation in t p may be only several nm.
[0027] Subsequently, the trenches are subjected to an electrochemical etch under applied bias voltage, wherein, in a preferred embodiment, the etch solution comprises aqueous solutions comprising water (H 2 O) and hydroxide (NH 4 OH or KOH). This results in the complete removal of layer 64 while leaving the region 62 substantially intact, forming an exposed n-type silicon surface 67 , as illustrated in FIG. 6 d . The three dimensional shape of the bottle trench shown in FIG. 6 d is in part determined by the shape of the neck region, which is, in turn, determined by the shape of mask used to form the initial vertical trench. Embodiments of the present invention include trenches formed from bottle shaped structures whose neck region in top-down view appears alternatively as an oval, a circle, a square, or a rectangle.
[0028] FIG. 7 illustrates an exemplary process flow of an embodiment of the current invention. After processing to form the dual-doped trench structures as depicted in FIG. 6 c , shown as step 70 in FIG. 7 , the silicon wafers containing the trench devices are placed in an electrochemical etching apparatus containing an hydroxide/water etch solution, step 71 . In a preferred embodiment, they are placed in a holder within the apparatus, which provides electrical contact to the backside of the silicon wafer, as depicted in FIG. 8 . A wafer 80 is held by clamps 82 , while an electrical contact is made to the backside wafer surface 81 . An electrical conductor 84 connects to a counter electrode 86 . A bias of approximately +1.2 V is subsequently applied between the wafer backside 81 and the counter electrode 86 in the etching apparatus. Etch step 71 is performed until the p+ silicon layer in the trench is completely removed. The wafer remains in the apparatus and subject to continued applied bias for a subsequent “overetch,” step 72 . The overetch step is performed to assure that the p+ layer is removed in all trenches so the overetch time employed preferably accounts for variations in process temperature, etch concentration, and related factors. In a preferred embodiment, the ratio of etch rates of p-type:n-type silicon (p:n etch selectivity) can be as high as 200:1, depending on the exact concentration of hydroxide and the solution temperature. For purposes of example, given nominal etch conditions having a p:n etch selectivity of 100:1 and a p-type removal rate of a 50 nm layer in 100 seconds, step 71 may be performed for 100 seconds to remove a 50 nm p+ region. Then overetch step 72 to remove any remnant p+ may be performed for an additional 50 second etch time, without substantial risk of etching significantly into the n-silicon region. Under nominal conditions where the 50 nm p-type layer is actually removed in exactly 100 seconds, the 50 seconds overetch of step 72 would remove only 0.25 nm of the n-type silicon region, about one layer of silicon atoms.
[0029] FIG. 9 helps explain the mechanism contributing to the enhanced p:n etch selectivity employed in the current invention. The graph shows that above a certain potential Si passivates (>−0.8 V). This characteristic applies for both n-type and p-type silicon. However, since the trench structure contains a reverse biased n/p junction, no current flows through the junction. Thus, the potential drop occurs at the n/p junction and not at the surface of the p layer where it contacts the etch solution. Thus, this leaves the p surface unbiased at open circuit potential and the p-type silicon is subject to continual hydroxide etch. When the n-type silicon is exposed, the current rises and causes immediate passivation of the surface, blocking any further etching.
[0030] After electrochemical etch to remove the sacrificial p-type layer, conventional steps, well-known to skilled artisans, are employed, including silicon doping to form the buried plate of the capacitor, step 73 in FIG. 7 , followed by capacitor dielectric deposition 74 and trench top electrode formation 75 .
[0031] An advantage of the current invention is that because of the high selectivity of the electrochemical etch step, the n-type layer 62 shown in FIG. 6 b acts as an etch stop, where the etch rate approaches zero once the n-silicon layer is contacted. Thus, the wet etch process no longer needs to be precisely controlled to determine the amount of silicon removed. Because the etch rate of n+ silicon is so low, one can vary etch concentration, time, and temperature within a wide range, without substantially altering the amount of silicon removed. Thus, in a preferred embodiment of the present invention, the amount of silicon removed during chemical etch is no longer determined by variations in the wet chemical etch process. Rather, the total silicon removed is simply determined by the depth of layer 64 , t p , since the etch process essentially terminates when the n-type layer 62 is encountered. Thus, as long as t p is sufficiently small that etch stop layer 66 remains between adjacent trenches, the chance of trench merge can be virtually eliminated.
[0032] As previously noted, another advantage of the present invention is the ability to fabricate larger bottle trenches for a given DRAM cell size. Referring to FIGS. 5 a - c , it is noted that in the present invention the variation in the amount of trench silicon removed, V, does not significantly depend on etch process variation, since the process is designed to remove all of the p+ layer without removing a significant amount of n-silicon. Thus, V arises only from variation in t p , which is on the order of a few nm. This affords the possibility of designing the nominal trench width to be much greater than in the conventional process, where no etch stop exists, resulting in a much larger V. A still further advantage of the current invention is that since V is so small, the variability in capacitance of trench capacitors among different DRAM cells is minimized.
[0033] An additional advantage of the current invention is that it is possible to scale the process so that it can be successfully employed in smaller DRAM cells in subsequent technologies. That is, as overall trench spacing decreases to accommodate greater device density and performance, the amount of silicon removed in the electrochemical etch process can be easily reduced. This is because the latter depends solely on the thickness of the sacrificial p-type layer, which is determined by precise doping methods.
[0034] Embodiments of structures and methods for fabrication of deep trench capacitors with enhanced uniformity and resistance to structural failure during processing have been described. In the foregoing description, for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of the present invention. It will be appreciated, however, by one skilled in the art that the present invention may be practiced without these specific details. Furthermore, one skilled in the art can readily appreciate that the specific sequences in which methods are presented and performed are illustrative and it is contemplated that the sequences can be varied and still remain within the spirit and scope of the present invention.
[0035] In the foregoing detailed description, structures and methods in accordance with embodiments of the present invention have been described with reference to specific exemplary embodiments. Accordingly, the present specification and figures are to be regarded as illustrative rather than restrictive. The scope of the invention is to be defined by the claims appended hereto, and by their equivalents.
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A method of forming trench capacitors in, e.g., a DRAM device, using an electrochemical etch with built-in etch stop to fabricate well-defined bottle-shaped capacitors is described. The process includes formation of a sacrificial silicon layer after initial deep trench formation, wherein the sacrificial layer is formed by doping, and upon its removal, a bottle trench is formed. A second region of doped silicon located below the sacrificial layer is resistant to the chemical etch performed to remove the sacrificial layer, and thereby renders the bottle trench formation process self-limiting.
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CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0001] Priority for this patent application is based upon provisional patent application 61/861,857 (filed on Aug. 2, 2013). The disclosure of this United States patent application is hereby incorporated by reference into this specification.
TECHNICAL FIELD
[0002] The current invention relates to lighting control systems for homes, offices, commercial spaces, parking, exterior perimeter and public areas; more particularly to wirelessly incorporating photo sensors into the lighting control systems for controlling lighting operation during daylight hours.
BACKGROUND OF THE INVENTION
[0003] Daylight control of lighting system illumination levels requires adjusting the output of a lighting fixture according to the amount of natural daylight in the immediate areas of the lighting fixture. Wired systems to control illumination level are well known in the art.
[0004] One possible scheme to accomplish this function is by integrating a photo sensor into a lighting fixture equipped with a light source to detect the level of natural light near the lighting fixture. Internally to the lighting fixture the photo sensor is connected to a light driver (e.g. a fluorescent ballast) or, if needed, a suitably designed intermediate device taking the input from the photo sensor and outputs a control signal. The photo sensor outputs ambient light level electrically to the light driver herein assuming the function if required by the intermediate device. The light driver then adjusts the level of electrical power delivered to the connected light source to affect the light level produced by the lighting fixture according to a preprogrammed algorithm. By lowering light output when natural ambient light is available in abundance and increasing light output when natural ambient light is low or not available, energy savings are achieved compared to the alternative practice of maintaining constant light output regardless of the availability of natural light. This method is referred to as “Daylight Harvesting” or “Daylight Control” or simply as “Daylighting”.
[0005] FIG. 1 illustrates one common implementation of daylight control with a fluorescent lighting fixture. In FIGS. 1 and 2 lighting apparatuses comprising 3 fluorescent lighting fixtures each comprising fluorescent tubes are depicted. A light driver in the form of a fluorescent ballast (labeled as Dimming Ballast) is provisioned with internal circuitry to provide a voltage supply to energize a photo sensor and internal circuitry to read the photo sensor signal. The output of the photo sensor is used to adjust the level which the light driver energizes the connected fluorescent tubes to affect light output. FIG. 1 specific depicts fluorescent lighting fixtures, but the same concept applies to other dimmable lighting technologies such as induction lights or solid state lights (SSL). For example, in the case of a SSL lighting fixture where the fluorescent tubes are replaced by light emitting diodes (LED) and the light driver is replaced by a dimmable LED driver (which may be alternatively referred to as LED power supply), the remaining circuitry of the daylight control would apply unchanged and would work in the same fashion as with the fluorescent lighting fixture.
[0006] In the approach illustrated by FIG. 1 , each lighting apparatus comprises a lighting fixture with an attached photo sensor to measure the surrounding ambient light level. Each lighting apparatus also functions autonomously and independently to all other lighting apparatus. In the event said lighting apparatus is in a location without natural ambient light, the photo sensor would be useless but yet the lighting apparatus would still carry the cost of the photo sensor. Additionally, in the system depicted in FIG. 1 the dimming function cannot be adjusted by other centralized controlling devices such as a manually operated dimming switch or a computer to automate light level control given the fixture by fixture control scheme.
[0007] In the scheme depicted in FIG. 1 each lighting apparatus could illuminate at a different brightness level compared to other nearby lighting apparatus due to the slight differences in the local ambient light level. This could be very distracting to human users of the illuminated space.
[0008] The scheme where the light driver such as a fluorescent ballast with integrated photo sensor circuitry is likely to be costly, limited in dimming functions to only “daylight control”, and unable to insure neighboring lighting apparatus will be similarly energized to produce uniform light level.
[0009] It will be demonstrated that the present invention solves the shortcomings of a lighting fixture with a light driver (e.g. fluorescent ballast) with integrated photo sensor circuitry and connected to a photo sensor mounted to the lighting apparatus.
[0010] FIG. 2 shows a scenario common in the current state of the art where a light driver, herein depicted in the form of a fluorescent ballast (labeled Dimming Ballast), has the internal circuitry to support an attached occupancy sensor in addition to a photo sensor. This further complicates the light driver with additional circuitry. Additional power capacity from a built-in power supply is needed to energize the occupancy sensor in addition to the photo sensor, and the light driver must be imbued with the ability to read the state of the occupancy sensor. This additional degree of integration requires the light driver to, in addition to its core function of energizing the lighting fixture, also support all the necessary input and output wiring connections within a very small form factor. Moreover, in order for the light driver to be able to support different light sources such as fluorescent, light emitting diode (LED), and induction light sources, the light driver, e.g. ballast, must be customized to incorporate the occupancy sensor circuitry and wireless processing if the occupancy sensor is to also control other lighting fixtures in the lighting zone. (For purposes of this specification, a group of lighting apparatuses controlled by a single photo sensor is referred to as a lighting zone.) An off-the-shelf light driver will not be capable of performing all these functions and therefore cannot be used which increases system cost.
[0011] It will be demonstrated that the present invention also resolves these issues via incorporating within a lighting zone a wireless control module with the circuitry and programming to interface with an occupancy sensor and photo sensor which would be compatible with a broad array of off-the-shelf light drivers and would be an improvement over the current state of the art.
[0012] Additional shortcomings of the present art of lighting fixtures comprising a light driver with integrated photo sensor circuitry include the following problems with incorporating the sensor interface functions within a light driver without use of a wireless control module:
[0000] each light fixture would need a photo sensor, occupancy sensor, or both, which would increase cost of the lighting fixture;
lighting fixtures belonging to the same lighting zone could be illuminated at a different brightness level due to local differences in ambient light level detected by each lighting fixture's photo sensor;
each light driver to be used with a different light source (e.g. LED light or an induction light driver) will need to be customized to incorporate the sensor interface circuitry before the lighting fixture can be used;
a photo sensor, occupancy sensor, or combination could not be shared across a lighting zone of lighting fixtures but must be duplicated for each lighting fixture because each lighting fixture would have the photo sensor or occupancy sensor built in;
and the lighting fixtures are incompatible with manual zone (e.g. centralized) level dimming using a manual control device (e.g. wall switch) or automated zone level dimming using a computer.
[0013] It will be demonstrated that the present invention solves these problems.
[0014] The novelty of this invention is to use a wireless control module to interface to a photo sensor and to transmit the output of the photo sensor or a derived control signal to other wireless control modules connected to additional light drivers configured to be in the same lighting zone.
[0015] By using a wireless control module incorporating photo sensor support circuitry to control a light driver rather than connecting the photo sensor support circuitry directly to the light driver, the wireless control module can be paired with different light drivers such as a light emitting diode (LED) light driver or an induction light driver, without first embedding the photo sensor support circuitry into the light driver. This allows the wireless control module to be compatible with off-the-shelf light drivers and lighting fixtures rather than requiring custom and substantially more expensive light drivers with built in photo sensor circuitry.
[0016] The use of separate wireless control modules also provides a much more flexible and widely applicable approach to zone lighting which allows a zone of lighting fixtures to be controlled by a single photo sensor which further allows all the lighting fixtures in the lighting zone to provide the same illumination level.
[0017] A separate photo sensor with a wireless control module will also allow for novel placement of the photo sensor. Traditional installation is to locate a lighting fixture in the ceiling. A photo sensor integrated into the lighting fixture must by default be located in the ceiling plane with the lighting fixture (although it is possible for the photo sensor to be located on the wall for lighting fixtures designed to be wall mounted). This precludes the possibility of locating the photo sensor on the working surface such as a desktop or tabletop in an office zone or on or near the floor in a corridor or walk path zone.
[0018] Locating the photo sensor on the working surface would have the benefit of detecting the lighting illumination level directly at the working surface and, by controlling the light output of the lighting fixture based on the illumination at the lighting surface, delivering the exact illumination level desired for the working surface. A photo sensor installed in the ceiling or wall could only control the approximate or averaged illumination level for the entire light zone or space. A photo sensor located on a working surface, in addition, would allow for more précised control of illumination level directly on the working surface, such as ensuring a desktop would be provided with 50 foot-candle of illumination or the floors in a hallway are illuminated to 30 foot-candle.
SUMMARY OF THE INVENTION
[0019] In FIG. 3 one preferred embodiment of the present invention is depicted. A room which receives natural daylight through an aperture such as a window 800 is represented. In the room, a series of lighting apparatuses 200 , 300 , 400 , each comprising a light driver 210 , 310 , 410 (fluorescent ballast labelled Dimming Ballast), a fluorescent light tube 220 , 320 , 420 , and a wireless control module 230 , 330 , 430 are depicted. A photo sensor 240 with circuitry separate from that of the light driver 210 is incorporated into the first lighting apparatus 200 and the photo sensor circuitry is incorporated into the first wireless control module 230 . The wireless control module 230 has built-in circuitry and programming to read the photo sensor 240 output and is capable of providing a dimming control signal to the light driver 210 according to a preprogrammed algorithm. Additionally, the wireless control module 230 may transmit the photo sensor 240 output or a control signal derived from the photo sensor 240 output to other lighting apparatuses 300 , 400 with wireless control modules 330 , 430 connected to light drivers 310 , 410 which drive fluorescent light tubes 320 , 420 . In this fashion a group of lighting apparatuses 200 , 300 , 400 are controlled by a single photo sensor 240 via the wireless control modules 230 , 330 , 430 which transmit an identical dimming control signal to each light driver 210 , 310 , 410 to insure uniform light output is produced by each fluorescent tube 220 , 320 , 420 .
[0020] In a preferred embodiment, the wireless control module 230 may also provide the necessary power supply required by the photo sensor 240 , such as a 12 VDC power supply or a 24 VDC power supply, to energize the photo sensor 240 .
[0021] Various preferred embodiments of the present invention will be shown to provide the following features.
[0022] Each preferred embodiment will comprise a wireless control module to be installed within a lighting fixture or installed external to the lighting fixture but in the range of the wireless modules in the same lighting zone, wherein the wireless control module will form a localized wireless network representing a lighting zone and the wireless control module will have a power supply to energize a photo sensor, the voltage of such to be 12 VDC, 24 VDC, or other voltage such as is customary where the system will be installed and used.
[0023] The wireless control module incorporating supporting circuitries for photo sensor and occupancy sensor would serve as the “coordinator” of the wireless network formed with other wireless modules. In FIG. 3 the wireless module labeled 230 would serve as the coordinator (which is readily understood by practitioners skilled in wireless networking) responsible for network creation, control of its parameters and basic maintenance, and connecting wireless modules labeled 330 and 430 into a wireless network. The benefit of this approach is eliminating the need for a separate wireless network coordinator required for a wireless network such as Zigbee.
[0024] The wireless control module will be able to read the output of the photo sensor measuring ambient light level and the wireless control module will be equipped to transmit the photo sensor output or a control value derived from the photo sensor to other wireless control modules configured to be in the same lighting zone.
[0025] The wireless control module may have sufficient power supply capacity to energize an occupancy sensor, the voltage of such to be 12 VDC, 24 VDC, or other voltage such as is customary where the system will be installed and used. If the wireless control module is installed in a lighting system which includes an occupancy sensor, the wireless control module will be able to read the output of the occupancy sensor installed to detect the presence or absence of inhabitants in the lighting zone and the wireless control module will be capable of transmitting that occupancy sensor output or a control value derived from the occupancy sensor to other wireless control modules configured to be in the same light zone.
[0026] The wireless control module may also be connected to a user interface device to allow a user to manually adjust the light output of a lighting zone by transmitting the manual settings to other wireless control modules configured to be in the same lighting zone.
[0027] The wireless control module may also be connected to a computer or other automated controller to automatically adjust the light output of a lighting zone by transmitting the automated brightness settings to other wireless control modules configured to be in the same light zone.
[0028] The wireless control module and photo sensor may also be installed ‘inverted’ compared to ceiling or fixture located photo sensor on the working surface (e.g. desktop, table top, floor, etc.) to directly control the illumination of the lighting fixtures in the same light zone to deliver the desired level of illumination.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Embodiments of the present invention will be described by reference to the following drawings, in which like numerals refer to like elements, and in which:
[0030] FIGS. 1 and 2 depict hard wired lighting systems;
[0031] FIG. 3 depicts an exemplary wireless lighting system using a photo sensor;
[0032] FIG. 4 depicts an exemplary wireless control module for a lighting system;
[0033] FIG. 5 depicts an exemplary wireless lighting system using a photo sensor and an occupancy sensor;
[0034] FIG. 6 depicts an exemplary wireless control module for a lighting system;
[0035] FIG. 7 depicts various examples of the light driver interfaces for dimming control;
[0036] FIG. 8 depicts the ON/OFF control of 0-10V compatible light driver where 0V or 10V do not correspond to zero light level output;
[0037] FIG. 9 depicts an exemplary wireless lighting system with a photo sensor and an occupancy sensor with a centralized control device for the manual adjustment of light output for all the lighting fixtures located in a single lighting zone;
[0038] FIG. 10 depicts an exemplary wireless lighting system with a photo sensor and an occupancy sensor with a centralized computer control device for the automated control of light output for all the light fixtures in a single lighting zone;
[0039] FIG. 11 depicts an exemplary wireless lighting system using a photo sensor that is located on a lighting fixture;
[0040] FIG. 12 depicts an exemplary wireless lighting system using a photo sensor that is located on representative working surfaces;
[0041] FIG. 13 depicts a flow chart for a method for wirelessly using a photo sensor within a lighting system;
[0042] FIG. 14 depicts a flow chart for a method for wirelessly using an occupancy sensor within a lighting system;
[0043] FIG. 15 depicts a flow chart for a method for wirelessly using a photo sensor and a computerized controller within a lighting system; and
[0044] FIG. 16 depicts a flow chart for a method for wirelessly using a photo sensor with a manual override within a lighting system.
DETAILED DESCRIPTION OF THE INVENTION
[0045] Referring to FIG. 3 a preferred embodiment of an exemplary lighting control system 200 for daylight control is depicted. As stated above, Daylight Control is a method of adjusting light output of Lighting Fixtures according to the output of a Photo Sensor measuring natural ambient light levels.
[0046] In the preferred embodiment depicted in FIG. 3 , the power to run lighting apparatuses and controllers is supplied externally and may be either 120V (at 50 or 60 Hz) or 277V (at 50 or 60 Hz). In other embodiments, the power supplied to the unit may be at different levels due to either voltage or current levels differing based upon local conditions, including battery powered. A room which receives natural daylight through an aperture such as a window 1600 is represented in FIG. 3 . In the room, a series of lighting apparatuses 200 , 300 , 400 , each comprising at least one light driver 210 , 310 , 410 (fluorescent ballast labelled Dimming Ballast), at least one light source (e.g. a fluorescent light tube) 220 , 320 , 420 , and a wireless control module 230 , 330 , 430 are depicted. It should be noted that the choice of three lighting apparatuses was made for ease of description and that the present teachings are applicable for systems with other quantities of lighting apparatuses. A photo sensor 240 with circuitry separate from that of the light driver 210 is incorporated into the first lighting apparatus 200 and the photo sensor circuitry is incorporated into the first wireless control module 230 . The wireless control module 230 has built-in circuitry and programming to read the photo sensor 240 output and is capable of providing a dimming control signal to the light driver 210 according to a preprogrammed algorithm. The connection to the light driver is a control signal where it will affect the brightness of the light source in a predictable and repeatable fashion.
[0047] Additionally, the wireless control module 230 may transmit the photo sensor 240 output or a control signal derived from the photo sensor 240 output to other lighting apparatuses 300 , 400 with wireless control modules 330 , 430 connected to light drivers 310 , 410 which drive fluorescent light tubes 320 , 420 . In this fashion a group of lighting apparatuses 200 , 300 , 400 are controlled by a single photo sensor 240 via the wireless control modules 230 , 330 , 430 which wirelessly transmit an identical dimming control signal to each light driver 210 , 310 , 410 to insure uniform light output is produced by each light source 220 , 320 , 420 .
[0048] In a preferred embodiment, the wireless control module 230 may also provide the necessary power supply required by the photo sensor 240 , such as a 12 VDC power supply or a 24 VDC power supply, to energize the photo sensor 240 .
[0049] FIG. 3 depicts the wireless control module 230 providing a DC voltage to energize the photo sensor 240 and has circuitry and programming to interpret the output of the photo sensor.
[0050] In the preferred implementation of the claimed invention depicted in FIG. 3 , the wireless control module 230 is provisioned to support the photo sensor 240 by providing suitable voltage to energize the photo sensor 240 and also to read and interpret the photo sensor 240 output. The same wireless control module 230 also has a mechanism to derive a dimming control signal based on the value of the photo sensor 240 output to adjust the brightness output of the light source 220 . The photo sensor 240 detects the level of natural ambient light available in the lighting zone. When the ambient light level is high the output of the light source 220 is dimmed, and when the ambient light level is low the output of the light source 220 is increased. Wireless control modules 330 , 430 connected to additional light drivers 310 , 410 are provided with the photo sensor signal or a derived control value wirelessly via wireless control module 230 . These wireless control modules 230 , 330 , 430 are preconfigured to belong to the same lighting zone.
[0051] FIG. 4 illustrates the internal functional elements of a wireless control module 530 . These internal functional elements include an AC to DC power supply 532 (which may be battery operated), a photo sensor interface 534 , a light driver interface 536 and a functional module 538 to process the sensor signal, light driver control signal and wireless communications, and a wireless transmitter 539 . This wireless control module 530 may be used to wirelessly control the light output of all lighting apparatuses in a single lighting zone based upon the input of a single photo sensor 540 . The photo sensor 540 detects ambient light levels in a single lighting zone and transmits a signal to the functional module 538 via the photo sensor interface 534 . The functional module 538 uses preprogrammed algorithms to determine the appropriate light output level and communicates this appropriate level to the light drivers 510 via the light driver interface. The light drivers 510 control the light sources 520 and the appropriate lighting level is produced. The wireless control module 539 may communicate with other wireless control modules controlling other lighting apparatuses in the same lighting zone to allow for all lighting apparatuses to output the correct lighting level required for the ambient light levels present in the lighting zone.
[0052] The AC to DC power supply provides the voltage to energize one or more Photo Sensors. The interface input circuitry (sensor interface) and programming are designed to read the output of the photo sensor and to interpret the measured natural ambient light level. The interface output circuitry and programming are designed to control the output of at least one light driver. The preprogrammed algorithm uses photo sensor measured ambient natural light level in the lighting zone to determine the control signal to transmit to at least one light driver. The wireless circuitry and programming are used to transmit photo sensor output or derived control value to other wireless control modules configured to operate in the same light zone. The wireless control modules connected to light drivers and light sources are configured to be operate in the same light zone and are the light sources are lit in unison to the common photo sensor output.
[0053] In the preferred embodiment depicted in FIG. 5 , the power to run lighting apparatuses and controllers is supplied externally and may be either 120V (at 50 or 60 Hz) or 277V (at 50 or 60 Hz). In other embodiments, the power supplied to the unit may be at different levels due to either voltage or current levels differing based upon local conditions, including battery powered.
[0054] A room which receives natural daylight through an aperture such as a window 1800 is represented in FIG. 5 . In the room, a series of lighting apparatuses 700 , 800 , 900 , each comprising at least one light driver 710 , 810 , 910 (fluorescent ballast labelled Dimming Ballast), at least one light source 720 , 820 , 920 , and a wireless control module 730 , 830 , 930 are depicted. A photo sensor 740 with circuitry separate from that of the light driver 710 is incorporated into the first lighting apparatus 700 and the photo sensor circuitry is incorporated into the first wireless control module 730 . An occupancy sensor 750 with circuitry separate from that of the light driver 710 is incorporated into the first lighting apparatus 700 and the occupancy sensor circuitry is incorporated into the first wireless control module 730 . In a preferred embodiment of the present invention, the occupancy sensor may be located on a wall within the light zone; in another preferred embodiment of the present invention, the occupancy sensor may be located on a ceiling within the light zone. The wireless control module 730 has built-in circuitry and programming to read the photo sensor 740 output and the occupancy sensor 750 output and is capable of providing a dimming control signal to the light driver 710 according to a preprogrammed algorithm. Additionally, the wireless control module 730 may transmit the photo sensor 740 output or a control signal derived from the photo sensor 740 output to other lighting apparatuses 800 , 900 with wireless control modules 830 , 930 connected to light drivers 810 , 910 which drive fluorescent light tubes 820 , 920 . The wireless control module 730 may also transmit the occupancy sensor 750 output or a control signal derived from the occupancy sensor 750 output to other lighting apparatuses 800 , 900 with wireless control modules 830 , 930 connected to light drivers 810 , 910 which drive fluorescent light tubes 820 , 920 . In this fashion a group of lighting apparatuses 700 , 800 , 900 are controlled by a single photo sensor 740 and a single occupancy sensor 750 via the wireless control modules 730 , 830 , 930 which wirelessly transmit an identical dimming control signal to each light driver 710 , 810 , 910 to insure uniform light output is produced by each fluorescent tube 720 , 820 , 920 .
[0055] In a preferred embodiment, the wireless control module 730 may also provide the necessary power supply required by the photo sensor 740 , such as a 12 VDC power supply or a 24 VDC power supply, to energize the photo sensor 740 and the occupancy sensor 750 .
[0056] In the preferred embodiment of the present invention depicted in FIG. 5 the wireless control module 730 is additionally provisioned to work with the occupancy sensor 750 by providing additional power supply capacity to energize the occupancy sensor 750 and also are provided with the circuitry and programming to read and interpret the output of the occupancy sensor 750 . The wireless control module 730 also has a mechanism to derive a control signal based on the state of the occupancy sensor 750 output to turn the light source 7200 N or OFF via a signal sent to the light driver 710 . The occupancy sensor 750 detects the presence or absence of inhabitants in the lighting zone. Wireless control modules 830 , 930 connected to additional light drivers 810 , 910 are also provided with the occupancy sensor 750 signal or a derived control value wirelessly via the first wireless control module 730 to energize or extinguish the light sources 820 , 920 accordingly via the light drivers 810 , 910 . These wireless control modules 730 , 830 , 930 are preconfigured to belong to the same lighting zone.
[0057] FIG. 5 depicts the wireless control module 730 providing a DC voltage to energize the photo sensor 740 and the occupancy sensor 750 and has circuitry and programming to interpret the output of the photo sensor 740 and of the occupancy sensor 750 .
[0058] As depicted in FIG. 6 , a wireless control module 630 can be extended to incorporate support for an occupancy sensor 650 . The occupancy sensor 650 detects the presence or absence of inhabitants in the lighting zone. In the event that inhabitant presence is detected, the state of the occupancy sensor 650 would change and forward a signal to the wireless control module 630 via an occupancy sensor interface 635 . In turn the wireless control module would dispatch a control signal via a light driver interface 636 to light drivers 610 to energize light sources 620 to an illumination level appropriate to the ambient light level detected by a photo sensor 650 . When the occupancy sensor 650 detects lack of inhabitant presence the sensor state would again change accordingly and a signal would be sent to the wireless control module 630 via the occupancy sensor interface 635 . The wireless control module 630 receiving indication of a lack of presence would dispatch a control signal via the light driver interface 636 to the light drivers 610 to turn off the light sources 620 regardless of the photo sensor 640 output sent to the wireless control module 630 via a photo sensor interface 634 . The wireless control module 630 is able to interpret the occupancy sensor 650 output and energize or extinguish the light source 620 via a signal to the light driver 610 depending on the occupancy state of the lighting zone.
[0059] The wireless control module 630 will transmit the occupancy sensor 650 output or a control value derived from the occupancy sensor 650 output to other wireless control modules configured to be in the same lighting zone and affects the ON/OFF status of lighting fixtures in the lighting zone
[0060] Furthermore, if in the lighting zone there other light drivers controlled by additional wireless control modules, the wireless control module 630 would transmit the state of the occupancy sensor 650 to the other wireless control modules installed in the lighting zone so all lighting fixtures in the entire lighting zone would be similarly controlled and the light output from the lighting fixtures would be of a consistent and compatible level. In this fashion the occupancy sensor 650 is able to control an entire lighting zone of lighting fixtures wirelessly.
[0061] The AC to DC power supply provides the voltage to energize one or more Photo Sensors. The photo sensor interface input circuitry (photo sensor interface) and programming are designed to read the output of the photo sensor and to interpret the measured natural ambient light level. The occupancy sensor interface circuitry and programming are designed to read the output of the occupancy sensor. The interface output circuitry and programming are designed to control the output of at least one light driver. The preprogrammed algorithm uses photo sensor measured ambient natural light level in the lighting zone and occupancy sensor output to determine the control signal to transmit to at least one light driver. The wireless circuitry and programming are used to transmit photo sensor output or derived control value and occupancy sensor output or derived control value to other wireless control modules configured to operate in the same light zone. The wireless control modules connected to light drivers and light sources are configured to be operate in the same light zone and are the light sources are lit in unison to the common photo sensor and occupancy sensor outputs.
[0062] A wireless control module with the circuitry and programming to interface with an occupancy sensor and photo sensor would be compatible with a broad array of off-the-shelf light drivers and is an improvement over the current state of the art.
[0063] FIG. 7 shows examples of three industry standard light driver interfaces to communicate the dimming control signal. The examples include 0-10 Vdc interface, DALI (Digitally Addressable Lighting Interface) or DMX. Off-the-self light drivers compatible with one of these industry standards (as well as other popular interfaces) would be compatible with the wireless control module invention and could readily be fitted to be controlled via a wireless control module. Preferably the control signal is an industry standard interface such as 0-10 Vdc, DALI or DMX. As those skilled in the art will recognize, the present invention may be used with additional means for control signal. Furthermore for 0-10 Vdc control interface an additional relay control output may be required to completely extinguish the light source.
[0064] FIG. 8 shows an embodiment where the wireless control module may be used to provide relay control to a relay connected in series with a light driver's AC service input for a light driver controlled via a 0-10 Vdc control interface. The relay control is needed because industry standard 0-10 Vdc control does not require the light source to be at zero illumination output when the control is at 0 Vdc and though the conditions would call for the light source to provide zero illumination output, the light source could still be outputting light even when the control is at 0 Vdc. In this case a separate relay is needed to interrupt the power input to the light driver and extinguish the light source completely. The wireless control module may be programmed to provide this relay control.
[0065] FIG. 9 illustrates another beneficial embodiment of the invention where a manual control device such as a wall switch or a scene controller is used with a wireless control module to allow for manual adjustment of the illumination level of lighting fixtures for a lighting zone. The wireless control module may incorporate circuitry and programming to read and interpret the manual control device. The wireless control module may transmit the manual setting from the manual control device to other wireless control modules configured to be in the same lighting zone.
[0066] In FIG. 9 , the lighting system of FIG. 5 is depicted with the lighting system having an additional wireless control module 1030 . The additional wireless control module 1030 is connected to a user interface device 1100 allowing manual adjustment of the output of the lighting fixtures 700 , 800 , 900 in the configured lighting zone. When a user attempts to manually control the output of the lighting fixtures 700 , 800 , 900 in the lighting zone, a signal is transmitted to wireless control module 1030 which wirelessly transmits the adjustment settings to the each of the other wireless control modules 730 , 830 , 930 in the same lighting zone. Each of the other wireless control modules 730 , 830 , 930 subsequently send signals to their controlled light drivers 710 , 810 , 910 to adjust the output of each light source 720 , 820 , 920 to the desired level.
[0067] In the preferred embodiment of the present invention depicted in FIG. 9 , the wireless control module 1030 is connected to the manual control device 1100 . Wireless control modules 730 , 830 , 930 connected to light drivers 710 , 810 , 910 are provided with the brightness setting or a derived control value wirelessly from the wireless control module 1030 connected to the manual control device 1100 and accordingly adjust the brightness output of the their light sources 720 , 820 , 920 .
[0068] FIG. 10 illustrates another beneficial embodiment of the invention wherein a computerized control device 1200 such as a computer is added to wirelessly control the lighting zone. The wireless control module may incorporate circuitry and programming to read and interpret the computerized control device. The wireless control module may transmit the commands from the computerized control device to other wireless control modules configured to be in the same lighting zone.
[0069] In FIG. 10 , the lighting system of FIG. 9 is depicted with a computerized control device 1200 replacing the manual control 1100 . The wireless control module 1030 in FIG. 10 is connected to a computerized control device 1200 allowing lighting control to be automated. The computerized control device 1200 uses a preprogrammed algorithm to send signals to the wireless control module 1030 which communicates with the other wireless control modules 730 , 830 , 930 . Each of the other wireless control modules 730 , 830 , 930 transmit signals to each light driver 710 , 810 , 910 which control the output of each lighting device 720 , 820 , 920 .
[0070] In the preferred embodiment depicted in FIG. 10 , the wireless control module 1030 is connected to a computerized control device 1200 . Wireless control modules 730 , 830 , 930 connected to light drivers 710 , 810 , 910 are provided with the brightness setting or a derived control value wirelessly from the wireless control module 1030 connected to the computerized control device 1200 and accordingly adjust the brightness output of the their light sources 720 , 820 , 920 .
[0071] FIG. 11 presents a depiction of the layout for one preferred embodiment of the present invention. In FIG. 11 , a room with a window for allowing natural daylight into the room, two desks for workstations, two light fixtures, and a photo sensor attached to one of the light fixtures is depicted. Using a control scheme such as that depicted in FIG. 3 allows for output from the single photo sensor to be used in determining and effecting the output of both light fixtures.
[0072] FIG. 12 presents a depiction of the layout for another preferred embodiment of the present invention. In FIG. 12 , a room with a window for allowing natural daylight into the room, two desks for workstations, two light fixtures, and two representative photo sensors mounted on either the floor or a work station is depicted. Using a control scheme such as that depicted in FIG. 10 allows for output from either photo sensor to be used in determining and effecting the output of both light fixtures.
[0073] FIG. 13 presents a flow chart of the method used to wirelessly incorporate the photo sensor 240 into the lighting system depicted in FIG. 3 . In step 2000 the photo sensor 240 detects and measures the ambient light level in the light zone. In steps 2010 and 2020 the photo sensor 240 converts the measured ambient light level to an analog representation of the ambient light level and outputs that analog value to the wireless control module 230 . In steps 2030 and 2040 the wireless control module 230 receives the analog representation of the ambient light level and uses an algorithm to convert the analog value to a light driver control value. In step 2050 the wireless control module transmits the light driver control value to the light driver 210 and to the other wireless control modules 330 , 430 in the light zone. Wireless control module 330 transmits the light driver control value to light driver 310 and wireless control module 430 transmits the light driver control value to light driver 410 . In step 2060 the light drivers 210 , 310 , 410 receive the light driver control value, The light drivers 210 , 310 , 410 use an algorithm to convert the control value to a light source power level and transmit the light source power level to the light sources 220 , 320 , 420 . In step 2070 the light sources 220 , 320 , 420 are adjusted to the appropriate output level. In step 2080 the process is repeated and the photo sensor 240 measures the ambient light level in the light zone.
[0074] FIG. 14 presents a flow chart of the method used to wirelessly incorporate the occupancy sensor 780 into the lighting system depicted in FIG. 5 . In step 3000 the occupancy sensor 780 detects whether the light zone is occupied. The occupancy sensor 780 may use any readily available means to detect occupancy in the light zone, such as passive infrared or by sound detection. In steps 3010 and 3020 the occupancy sensor 780 converts the measured occupancy state of the light zone to a digital value and outputs that digital value to the wireless control module 730 . In steps 3030 and 3040 the wireless control module 730 receives the digital value from the occupancy sensor 780 and uses an algorithm to derive a light driver control value. In step 3050 the wireless control module transmits the light driver control value to the light driver 710 and to the other wireless control modules 830 , 930 in the light zone. Wireless control module 830 transmits the light driver control value to light driver 810 and wireless control module 930 transmits the light driver control value to light driver 910 . In step 3060 the light drivers 710 , 810 , 910 receive the light driver control value, The light drivers 710 , 810 , 910 use an algorithm to convert the control value to a light source power level and transmit the light source power level to the light sources 720 , 820 , 920 . In step 3070 the light sources 720 , 820 , 920 are adjusted to the appropriate output level. In step 3080 the process is repeated and the occupancy sensor 780 measures the occupancy state in the light zone.
[0075] FIG. 15 presents a flow chart of the method used to wirelessly incorporate the user selected manual adjustment to the light input level into the lighting system depicted in FIG. 9 . In step 4000 an individual located in or outside the light zone selects a desired light level for the light zone using the manual control device 1100 . In steps 4010 and 4020 the manual control device 1100 converts the selected ambient light level to a control command and outputs that control command to the wireless control module 1030 . In steps 4030 and 4040 the wireless control module 1030 receives the control command and uses an algorithm to convert the analog value to a light driver control value. In step 4050 the wireless control module 1030 transmits the light driver control value to the other wireless control modules 730 , 830 , 930 in the light zone. Wireless control module 730 transmits the light driver control value to light driver 710 , wireless control module 830 transmits the light driver control value to light driver 810 and wireless control module 930 transmits the light driver control value to light driver 910 . In step 4060 the light drivers 710 , 810 , 910 receive the light driver control value, The light drivers 710 , 810 , 910 use an algorithm to convert the control value to a light source power level and transmit the light source power level to the light sources 720 , 820 , 920 . In step 4070 the light sources 720 , 820 , 920 are adjusted to the appropriate output level. In step 4080 the process is repeated and the manual control device 1100 is set or remains set at the desired user level.
[0076] FIG. 16 presents a flow chart of the method used to wirelessly incorporate computer selected light output level for the light input level into the lighting system depicted in FIG. 10 . In step 5000 an individual such as an occupant, technician or specialist programs a computerized control device 1200 to a desired light level for the light zone. The programming may be performed once, infrequently, or frequently. As those skilled in the art are aware, the frequency of adjusting the programming does not alter the novelty of the present invention. In steps 5010 and 5020 the computerized control device 1200 converts the selected ambient light level to a control command and outputs that control command to the wireless control module 1030 . The command or sequence of commands may be outputted to satisfy the programming embodying the desired behavior of a single light zone or multiple light zones. In steps 5030 and 5040 the wireless control module 1030 receives the control command and uses an algorithm to convert the analog value to a light driver control value. In step 5050 the wireless control module 1030 transmits the light driver control value to the other wireless control modules 730 , 830 , 930 in the light zone. Wireless control module 730 transmits the light driver control value to light driver 710 , wireless control module 830 transmits the light driver control value to light driver 810 and wireless control module 930 transmits the light driver control value to light driver 910 . In step 5060 the light drivers 710 , 810 , 910 receive the light driver control value, The light drivers 710 , 810 , 910 use an algorithm to convert the control value to a light source power level and transmit the light source power level to the light sources 720 , 820 , 920 . In step 5070 the light sources 720 , 820 , 920 are adjusted to the appropriate output level. In step 4080 the process is repeated and the wireless control module 1030 receives the control command.
[0077] Although several embodiments of the present invention, methods to use said, and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. The various embodiments used to describe the principles of the present invention are by way of illustration only and should not be construed in any way to limit the scope of the invention. Those skilled in the art will understand that the principles of the present invention may be implemented in any suitably arranged lighting system.
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Disclosed is a means to implement wireless daylight control of light level for a group of lighting fixtures configured to operate in the same light zone, by measuring the amount of natural daylight available in the immediate areas using a photo sensor connected to a wireless control module and wirelessly transmitting the photo sensor output or a derived value based on the photo sensor output. The wireless control can be further supplemented with occupancy control, manual adjustments and automated computerized control of the lighting fixtures configured to operate in the same light zone.
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FIELD OF THE INVENTION
This invention generally relates to control sticks of aircraft and more particularly to the tactile feel during actuation of the control stick.
BACKGROUND OF THE INVENTION
As the performance requirements of both military and commercial aircraft increases, conventional control technologies cannot relieve the pilot from higher mental and manual control activity. As such, today's high performance aircraft as well as some transport aircraft use sidesticks, center sticks, yokes, joysticks and control columns. As used herein, these devices will be generically referred to either as “control columns” or “control sticks,” with these terms being generally synonymous in a generic sense.
The commercial and military aircraft industry is under pressure from both government and private consumer groups to build aircraft that is both safe and economical. Safety standards are imposed on the aircraft industry such that a safe and reliable experience is had for customers. Also, of importance to the aircraft industry is to build aircraft that present an economic solution to a customer's needs. A large factor that addresses economic concerns is the overall weight of an aircraft. A lighter aircraft will generally be cheaper to operate because generally the aircraft (within its flight class) will require less fuel to operate, among other reasons.
The tactile feel of the control sticks of an aircraft are an important safety aspect. The pilot needs to have tactile feedback in order to tell certain operating conditions for the engine(s) and various control systems present on modern aircraft.
One such tactile feel are detents. Typically, the detent feel provided for in the control sticks is created from a mechanical detent structure that will indicate to the person actuating the control stick that the aircraft is now in some specific mode or range of operation. However, mechanical systems are not ideal because they are both complex and heavy. Furthermore, a mechanical detent structure does not allow for the feel of the detent to be easily changed.
Therefore, electrical systems were created to reduce the complexity and weight of the previous mechanical system and allow for the ability to more easily alter the feel of the detent. Initially, analog electronic control systems were used to provide the control signals for a simple motor that would provide the detent feel. However, these analog systems were difficult to control in that they experienced a very low tolerance for component variability and would drift in operation range over time of operation and temperature during operation. To remedy this issue digital systems were implemented.
The digital systems typically use force sensors to sense the torque the operator applies to the control stick. By sensing the force applied to the control stick the digital system can determine how to properly simulate the mechanical detent feel. However, having to either sense or derive force can be a complex process in and of itself
Therefore, there is a need for a safe and cost effective simulated detent feel solution that eliminates the heavy and complex mechanical solution and the overly complex digital force sensing solution. Embodiments of the present invention provide such a solution. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.
BRIEF SUMMARY OF THE INVENTION
In one embodiment, the invention provides a control stick system for an aircraft. The control stick system comprises a lever, a motor operably coupled to the lever, and a controller for controlling the motor. The controller causes the motor to bias the lever in such a manner to simulate a detent mechanism. To control the motor the controller uses a position measurement and a speed measurement of the motor and a position measurement and a speed measurement of the lever.
The position and speed measurements of both the motor and the lever come from sensors within the control stick system. A first sensor is configured to measure the speed and position of a rotor of the motor, and a second sensor is configured to measure the speed and position of the lever.
In another embodiment of the present invention, the motor is a brushless DC motor. A controller provides a drive current to the brushless DC motor that is based on position and speed measurements of a lever and position and speed measurements of a rotor of the brushless DC motor. The controller derives the drive current by providing the speed and position measurements to a series of proportional/integrator loops configured to adjust the drive current according to a preprogrammed simulated detent position.
In another embodiment, the invention provides a method of simulating a detent mechanism. A detent mechanism is simulated by sensing the position and speed of a lever, and sensing the position and speed of a rotor of a motor that is operably coupled to the lever. A controller operates the motor such that the motor biases the lever to simulate a detent mechanism based on the position and speed measurements.
In yet another embodiment, the invention provides a control stick system for an aircraft. The control stick system comprises a lever coupled to a first gear. The first gear is operably coupled to a slip clutch that is operably coupled to a reversible gear train. The reversible gear train is coupled to a motor that is configured to operably bias the lever by providing a torque to the reversible gear train.
Furthermore, the control stick system has a first resolver to measure a speed and a position of the lever, and a second resolver to measure a speed and a position of the motor. Both the first and the second resolver provide the speed and position measurements to a controller for the motor such that the motor biases the lever in such a manner to simulate a detent mechanism.
Other aspects, objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings:
FIG. 1 is a block diagram of the mechanics of a control stick system in accordance with an embodiment of the present invention;
FIG. 2 is a block diagram of a controller of the control stick system, in accordance with an embodiment of the present invention; and
FIG. 3 is a simulated symmetrical detent according to an embodiment of the present invention.
While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
Turning now to the drawings, there is illustrated in FIG. 1 a block diagram of a mechanical lever and gear structure of a control stick detent system 100 . The control stick system 100 includes a lever 102 . Lever 102 is coupled to slip clutch 106 . The slip clutch 106 serves as a safety device. Essentially, if the motor control (discussed subsequently) malfunctions, such that the user is unable to actuate the lever 102 , the slip clutch 106 allows the user to override the motor control.
The slip clutch 106 interfaces with the reversible gear train 108 . The reversible gear train 108 allows the user to actuate the lever 102 in either a forward or backward motion.
The motor 112 is configured to provide a torque to the reversible gear train 108 such that the user will experience a simulated detent feel when actuating the lever 102 . To accomplish this at least two sensors are needed. Resolver 114 is needed to detect the position and speed of the lever 102 , and resolver 116 is needed to detect the position and speed of the rotor 110 . In the embodiment of the invention shown in FIG. 1 , both sensors are resolvers. However, other sensors are contemplated such as a RVDT or a potentiometer.
Additionally, in the embodiment of the invention shown in FIG. 1 , only a single resolver is shown for each the motor 112 and the lever 102 . However, in other embodiments of the present invention multiple sensors are contemplated. The multiple sensors provide redundant systems in case of the failure of a primary or even a secondary sensor.
The control stick detent system 100 also includes a controller module 118 that is communicatively coupled to both sensor 116 and sensor 114 . Speed and position information from sensors 116 and 114 is used by a control system of the controller module 118 . The control system derives a supply current for motor 112 , which in a particular embodiment is contemplated to be a brushless DC motor. This supply current controls the motor 112 such that the torque applied to the reversible gear train 108 (from FIG. 1 ) of the simulates a mechanical detent feel for the user.
A block diagram of the control system 200 of the controller module 118 is shown in FIG. 2 . The control system 200 is preferably implemented in software that operates on the controller module 118 (from FIG. 1 ). The control system 200 calculates the desired torque to be produced by the motor 112 (from FIG. 1 ) based on position and speed information of the lever 102 from sensor 116 , and position and speed information of the rotor 110 of motor 112 from sensor 114 .
Control system 200 is composed of a series of three closed proportional/integrator (PI) loops. The three PI loops are a position PI controller 204 , a speed PI controller 206 , and a motor current PI controller 208 . Additionally, the control system includes a control software module 202 that operates the three control loops 204 , 206 , and 208 .
Essentially, the control software module 202 determines the position of the lever 102 from information provided from sensor 116 . Using that position determination, the control software module 202 further determines if lever 102 is in a range of a simulated detent or not in a range of the simulated detent. The simulated detent ranges are user defined and preprogrammed in the control system 200 and provided to both the position PI controller 204 and the control software module 202 .
Accordingly, the control software module 202 determines that the lever 102 is either in a simulated detent range or outside of a simulated detent range. If the control software module 202 determines that the lever 102 is not in a simulated detent range, then the control system 200 runs the motor 112 at a constant current so as to provide a resistance that mimics the feel of being between detent positions of a traditional mechanical system. If the control software module 202 determines that the lever 102 is in the range of a simulated detent, then the control system 200 runs the three PI loops 204 , 206 , and 208 to provide PI position control with the desired lever 102 position set at the center of the simulated detent.
The position PI controller 204 has inputs that represent the center point of the simulated detent and the current position of lever 102 , as given by sensor 116 (from FIG. 1 ). The position PI controller calculates the difference between the center point of the simulated detent and the lever position to obtain an error. The position PI controller 204 then integrates the error to determine an average error. The actual error is added to the average error, which represents a saturation level called the speed command that is provided to the speed PI controller 206 .
Along with the speed command input, the speed PI controller 206 also takes the lever speed, from sensor 116 , as an input. Using these two inputs, the speed PI controller calculates the difference between the speed command and the lever speed (obtained from sensor 116 ) to obtain an error. The speed PI controller 206 then integrates the error to determine an average error. The difference is added to the average error, which represents a saturation level called the torque command that is provided to the motor current PI controller 208 .
Along with the torque command input, a torque saturation limit input is provided to the motor current PI controller 208 from the control software module 202 . The torque saturation limit is a preset value that sets a limit of the required torque needed to overcome the torque command. The motor current PI controller 208 determines a difference between the torque command and the torque saturation limit to obtain an error. The motor current PI controller 206 then integrates the error to determine an average error. The average error is added to the actual error to determine a motor drive current. The torque saturation limit will be different depending on what zone (discussed below) the lever 102 is currently in within a simulated detent range.
An individual simulated detent range is composed of multiple zones in which the motor 112 (from FIG. 1 ) operates with a different drive current in order to provide a different resistance profile corresponding to the desired shape of the simulated detent. Therefore, by defining different zones and correlating that to motor 112 drive current, various simulated detent shapes can be achieved.
FIG. 3 shows a symmetric simulated detent 300 in accordance with a particular embodiment of the present invention. The simulated detent 300 shows a single detent range 304 with two zones. The first zone 306 is defined to be from the start of the detent range 308 to the center of the detent 310 . The second zone 308 is the center of the detent 310 to the end of the detent range 304 .
In the first zone 306 , the control software module 202 (from FIG. 2 ) sets the torque saturation limit to a constant to simulate the flat slope of the first zone 306 . As the user actuates the lever 102 (from FIG. 1 ) and moves it into the first zone 306 the position PI controller 204 and the speed PI controller 206 detect the speed and position error of the lever 102 . While the error persists, the integrator portions of the position PI controller 204 and the speed PI controller 206 gradually increase the motor drive current up to the torque saturation limit set by the control software module 202 .
In the second zone 308 , the control software module 202 (from FIG. 2 ) sets the torque saturation limit higher to simulate the feel of the lever 102 (from FIG. 1 ) clicking into a detent. While the lever 102 is in the second zone, the torque saturation limit is left at the increased level such that an increased force is required from the user to unseat the lever 102 out of the detent.
The actual values of the torque saturation limit are heavily influenced by the interactions of the mechanical properties of the reversible gear train 108 (from FIG. 1 ), the motor 112 , and the control electronics module 118 . Therefore, the torque saturation limit value is set experimentally to produce the desired push-back forces. Generally, the torque saturation limit of the second zone 308 should be twice the torque saturation limit of the first zone 306 .
All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
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A control stick system for simulating a detent mechanism in an aircraft is provided. The detent mechanism is simulated by a motor operably coupled to a lever and configured to bias the lever such that the user experiences the feel of a traditional detent mechanism. A controller operates the motor that provides the simulated detent by receiving data from multiple sensors regarding the position and the speed of the lever and the position and the speed of a rotor assembly of the motor. Using the position and the speed measurements, the controller is able to detect when the lever is entering a specific zone of a simulated detent range. Depending on what zone the lever is in, within the simulated detent range, the controller is configured to provide a different drive current to the motor.
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FIELD OF THE INVENTION
The present invention is related to a new use of a potent product extracted from rhizomes of Zingiber officinale in treating a disease associated with Helicobacter pylori such as gastritis, gastric ulcer or duodenal ulcer in a patient.
BACKGROUND OF THE INVENTION
Chinese crude drugs or spices eg. Zingiber officinale, Eugenia caryophyllata, Allium sativum , have been used in medicine and in flavoring foods. Crude ginger is used as an anti-emetic and expectorant, an anti-tussive and accelerator of the digestive organs. Semi-dried old crude ginger is also used for stomachache, chest pain, low back pain, cough, common cold and as a cure for a form of edema being called “stagnate of water”. Zingerone is the major component which accounts for the spicy character of ginger; gingerol and shogaol are other pungent components in ginger. Gingerol has cardio-tonic action, suppresses the contraction of isolated portal veins in mice, and modulates the eicosanoid-induced contraction of mouse and rat blood vessels. Both gingerol and shogaol are mutagenic, whereas zinger and zingerone have been found to exhibit antimutagenic activity. Shogaol has inhibitory activity on the carrageenin-induced paw edema and platelet aggregation [U.S. Pat. No. 5,804,603, Background of the Invention].
U.S. Pat. No. 6,855,347 discloses a composition for treating gastric ulcer and a process for preparing the same, wherein the composition comprising an extract obtained from the plant parts of Aegle marmetos and Withania somnifra and from the plant parts of at least one member selected from the group consisting of eight plants, wherein one of them is Zingiber officinale . The extract of the composition is preferably an aqueous extract.
Japanese patent publication No. 2004-115536 discloses anti- Helicobacter pylori potent product useful for prophylaxis and treatment of gastritis and gastric and duodenal ulcer, which comprises using one or more galenicals selected from Sophorae radix, Anisi stellati Frutus, Myristica fragrans, Isodon japonicus Hara, Swertia japonica, Florence fennel, Zingiber siccatum, Atractylodes rhizome , ginger, Saussureae radix and gayangae rhizoma.
It is concluded in the study of an article published in Anticancer Research 23(5A): 3699-3702, 2003, that ginger root extracts containing the gingerols inhibit the growth of H. pylori CagA+ strains.
SUMMARY OF THE INVENTION
An objective of the present invention is to provide a potent product in treating a disease associated with Helicobacter pylori which is prepared from rhizomes of Zingiber officinale . Preferably, the potent product prepared in the present invention is significantly more effective in comparison with a crude aqueous extract or a crude organic solvent extract from rhizomes of Zingiber officinale.
It is disclosed in the present invention that an aqueous eluate obtained by subjecting the crude organic solvent extract to an elution treatment with a reverse phase chromatography column has the weakest potency in treating said disease, and an eluate of an eluent having a relatively lower polarity has an improved potency. It is surprised to find that an eluate of an eluent having a polarity sufficiently low so that the eluate is free of both 6-gingerol and 6-shogaol has the strongest potency. This finding is advantageous because 6-gingerol and 6-shogaol are pungent components and are relatively less stable chemicals.
Preferred embodiments of the invention include (but not limited to) the following:
1. A method of treating a disease associated with Helicobacter pylori in a patient comprising administering to the patient a therapeutically effective amount of a potent product prepared from rhizomes of Zingiber officinale , said potent product being prepared by a process comprising the following steps:
a) preparing a crude extract from rhizomes of Zingiber officinale , said crude extract comprising 6-gingerol and 6-shogaol;
b) introducing the crude extract to a reverse phase chromatography column or a normal phase chromatography column, and eluting the column with a first eluent and a second eluent in sequence, i) said first eluent having a polarity lower than water and said second eluent having a polarity lower than that of the first eluent when the reverse phase chromatography column is used, or ii) said second eluent having a polarity lower than that of a mixture of ethyl acetate (EA) and methanol in a weight ratio of 1:1 and said first eluent having a polarity lower than that of the second eluent when the normal phase chromatography column is used, so that a first eluate resulting from elution of the first eluent and a second eluate resulting from elution of the second eluent are obtained; and
c) removing the first eluent from the first eluate by evaporation, so that a first concentrated eluate is obtained and is able to be used as the potent product or removing the second eluent from the second eluate by evaporation, so that a second concentrated eluate is obtained and is able to be used as the potent product;
wherein step a) comprises steps i) to iv), or comprises step I), step I′), or step I″), wherein said steps i) to iv) are:
i) shedding fresh rhizomes of Zingiber officinale and filtering the resulting mixture to obtain a filtrate and a residue;
ii) extracting the filtrate with a first organic solvent, recovering the resulting extraction solution of the first organic solvent, and evaporating the first organic solvent from the extraction solution to obtain a first concentrated extraction solution;
iii) extracting the residue with a second organic solvent, recovering the resulting extraction solution of the second organic solvent, and evaporating the second organic solvent from the extraction solution to obtain a second concentrated extraction solution; and
iv) combining the first concentrated extraction solution and the second concentrated extraction solution to obtain the crude extract;
said step I) is:
I) extracting dried rhizomes of Zingiber officinale with an organic solvent which is the same as said second organic solvent, recovering the resulting extraction solution of the organic solvent, and evaporating the organic solvent from the extraction solution to obtain the crude extract;
said step I′) is:
I′) steam distilling dried rhizomes of Zingiber officinale , and concentrating the resulting distillate by evaporation to obtain the crude extract; and
said step I″) is:
I″) extracting powder of dried rhizomes of Zingiber officinale with supercritical CO 2 , recovering the resulting extraction solution of the supercritical CO 2 , and evaporating CO 2 from the extraction solution to obtain the crude extract.
2. The method according to Item 1, wherein said disease is gastric ulcer.
3. The method according to Item 1, wherein said crude extract is prepared from the method comprising step i) to iv).
4. The method according to Item 3, wherein said first organic solvent is ethyl ether, and said second organic solvent is acetone, methanol, ethanol, a mixture of methanol and water, a mixture of ethanol and water, or a combination of them
5. The method according to Item 4, wherein said second organic solvent is acetone.
6. The method according to Item 1, wherein said crude extract is prepared from the method comprising step I).
7. The method according to Item 6, wherein said organic solvent is acetone, methanol, ethanol, a mixture of methanol and water, a mixture of ethanol and water, or a combination of them.
8. The method according to Item 7, wherein said organic solvent is acetone, ethanol or a mixture of ethanol and water.
9. The method according to Item 1, wherein the reverse phase chromatography column is used, and the first eluent has a polarity lower than that of a mixture of ethanol and water having 40% of ethanol by weight.
10. The method according to Item 9, wherein the first eluent is methanol, a mixture of methanol and water, ethanol, a mixture of ethanol and water, a mixture of acetone and water, or a combination of them.
11. The method according to Item 10, wherein the first eluent is a mixture of ethanol and water.
12. The method according to Item 11, wherein the reverse phase chromatography column is eluted with water prior to the first eluent.
13. The method according to Item 9, wherein said potent product is said first concentrated eluate, and said first concentrated eluate comprises 6-gingerol and 6-shogaol.
14. The method according to Item 1, wherein the reverse phase chromatography column is used, said potent product is said second concentrated eluate, and the first eluent has a polarity lower than that of a mixture of ethanol and water having 40% of ethanol by weight.
15. The method according to Item 14, wherein said second eluent is acetone, a mixture of acetone and water, a mixture of acetone and methanol, a mixture of acetone and ethanol, a mixture of acetone and C4-C6 alkane, C4-C6 alkane, a mixture of C4-C6 alkane and methanol, a mixture of C4-C6 alkane and ethanol, or a combination of them.
16. The method according to Item 15, wherein said second eluent is acetone.
17. The method according to Item 14, wherein said second concentrated eluate is substantially free of 6-gingerol or 6-shogaol.
18. The method according to Item 14, wherein said second concentrated eluate is substantially free of both 6-gingerol and 6-shogaol.
19. The method according to Item 1, wherein the normal phase chromatography column is used, said potent product is said first concentrated eluate, and the first eluent has a polarity lower than that of a mixture of n-hexane and ethyl acetate in a weight ratio of 6:4.
20. The method according to Item 19, wherein the first eluent has a polarity close to that of a mixture of n-hexane and ethyl acetate in a weight ratio of 9:1.
21. The method according to Item 20, wherein the first eluent is a mixture of n-hexane and ethyl acetate in a weight ratio of 9:1.
22. The method according to Item 19, wherein said first concentrated eluate is substantially free of 6-gingerol or 6-shogaol.
23. The method according to Item 19, wherein said first concentrated eluate is substantially free of both 6-gingerol and 6-shogaol.
24. The method according to Item 1, wherein the normal phase chromatography column is used, said potent product is said second concentrated eluate, the second eluent has a polarity close to that of a mixture of n-hexane and ethyl acetate in a weight ratio of 6:4, and said second concentrated eluate comprises 6-gingerol and 6-shogaol.
25. The method according to Item 24, wherein said second eluent is a mixture of n-hexane and ethyl acetate in a weight ratio of 6:4.
The potent product is preferably administered orally.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 to FIG. 20 are the results of HPLC analysis of Sample 1 to Sample 20 prepared in the present application.
DETAILED DESCRIPTION OF THE INVENTION
The applicant of this application in GB 2366565 discloses a method of preparing an extract from Zingiber officinale , which is potent in anti-inflammation, anti-platelet aggregation and anti-fungal activity, includes the following steps: preparing a crude liquid from rhizomes of ginger by extraction with an organic solvent or supercritical CO 2 or by distillation with steam; introducing the crude liquid to a reverse phase chromatography column, and eluting the column with water, a first eluent and a second eluent having a polarity lower than that of the first eluent but higher than that of chloroform, so that a first eluate resulting from elution of the first eluent and a second eluate resulting from elution of the second eluent are obtained; removing the first eluent and the second eluent from the first eluate and the second eluate by evaporation, respectively, so that a first concentrated eluate and a second concentrated eluate are obtained as the potent extract. The details disclosed in GB 2366565 are incorporated herein by reference.
The invention is further described by means of example, but not in any limitative sense.
Percentages and other amounts referred to in this specification are by weight unless indicated otherwise. Percentages are selected from any ranges used to total 100%.
Example 1
Sliced shade dried rhizomes of ginger were pulverized and screened with a sieve of mesh No. 10. One part by weight of the resulting powder was mixed with 8 parts by weigh of 95% ethanol, and the resulting mixture was boiled under refluxing for one hour and filtered to obtain a filtrate A and a residue. The residue was mixed with 95% ethanol in a weight ratio of 1:8, and the resulting mixture was boiled under refluxing for one hour and filtered to obtain a filtrate B. The filtrate A and filtrate B were combined, and it was concentrated in a water bath of 70° C. and in vacuo (Rotavapor R-220, BÜCHI, Switzerland) by evaporating the solvent therefrom. The resulting concentrate was introduced to a reverse phase chromatography column (7.1 cm×90 cm) packed with Diaion® HP-20 resin (Mitsubishi, Japan) in an amount of 20 times by dry weight of the concentrate of the combined filtrate, which was then eluted with 5 bed volumes of water, 4 bed volumes of 40% ethanol and 4 bed volumes of acetone in sequence. The eluate from the elution of 40% ethanol, and the eluate from the elution of acetone were collected separately. The eluate from 40% ethanol was concentrated in vacuo (Rotavapor R-220, BÜCHI, Switzerland) to dry, and then concentrated again in a water bath of 80° C. and in vacuo (40 mbar) for one hour to obtain Sample 1. The eluate from acetone was concentrated in vacuo (Rotavapor R-220, BÜCHI, Switzerland) to dry, and then concentrated again in a water bath of 80° C. and in vacuo (40 mbar) for one hour to obtain Sample 2.
Example 2
The procedures of Example 1 were repeated except that the eluent of 40% ethanol was replaced by 70% ethanol. Sample 3 was obtained from the elution of 70% ethanol, and Sample 4 was obtained from the elution of acetone.
Example 3
The procedures of Example 1 were repeated to obtain Sample 5, except that the eluent of 40% ethanol was replaced by 95% ethanol.
Example 4
Sliced shade dried rhizomes of ginger were pulverized and screened with a sieve of mesh No. 10. One part by weight of the resulting powder was mixed with 8 parts by weigh of 95% ethanol, and the resulting mixture was boiled under refluxing for one hour and filtered to obtain a filtrate A and a residue. The residue was mixed with 95% ethanol in a weight ratio of 1:8, and the resulting mixture was boiled under refluxing for one hour and filtered to obtain a filtrate B. The filtrate A and filtrate B were combined, and it was concentrated in a water bath of 70° C. and in vacuo (Rotavapor R-220, BÜCHI, Switzerland) to ⅕ of its original weight by evaporating the solvent therefrom. To the resulting concentrate 4 times by weight of water was added to resume its original weight, and the resulting liquid was introduced to a reverse phase chromatography column (7.1 cm×90 cm) packed with Diaion® HP-20 resin (Mitsubishi, Japan) in an amount of 20 times by dry weight of the concentrate of the combined filtrate, which was then eluted with 1 bed volume of 20% ethanol and 4 bed volumes of 70% ethanol in sequence. The eluate from the elution of 70% ethanol was collected and concentrated in vacuo (Rotavapor R-220, BÜCHI, Switzerland) to dry, and then concentrated again in a water bath of 80° C. and in vacuo (40 mbar) for one hour to obtain Sample 6.
Example 5
The procedures of Example 4 were repeated to obtain Sample 7, except that the eluent of 70% ethanol was replaced by 95% ethanol.
Example 6
Sliced shade dried rhizomes of ginger were pulverized and screened with a sieve of mesh No. 10. One part by weight of the resulting powder was mixed with 8 parts by weigh of 95% ethanol, and the resulting mixture was stirred in a homogenizer at 2000 rpm (Type X 50/10, Ystral, Germany) for one hour and filtered to obtain a filtrate A and a residue. The residue was mixed with 95% ethanol in a weight ratio of 1:8, and the resulting mixture was stirred in a homogenizer at 2000 rpm for one hour and filtered to obtain a filtrate B. The filtrate A and filtrate B were combined, and it was concentrated in a water bath of 70° C. and in vacuo (Rotavapor R-220, BÜCHI, Switzerland) to ⅕ of its original weight by evaporating the solvent therefrom. To the resulting concentrate 4 times by weight of water was added to resume its original weight, and the resulting liquid was introduced to a reverse phase chromatography column (7.1 cm×90 cm) packed with Diaion® HP-20 resin (Mitsubishi, Japan) in an amount of 20 times by dry weight of the concentrate of the combined filtrate, which was then eluted with 1 bed volume of 20% ethanol and 4 bed volumes of 70% ethanol in sequence. The eluate from the elution of 70% ethanol was collected and concentrated in vacuo (Rotavapor R-220, BÜCHI, Switzerland) to dry, and then concentrated again in a water bath of 80° C. and in vacuo (40 mbar) for one hour to obtain Sample 8.
Example 7
The procedures of Example 6 were repeated to obtain Sample 9, except that the eluent of 70% ethanol was replaced by 95% ethanol.
Example 8
Sliced shade dried rhizomes of ginger were pulverized and screened with a sieve of mesh No. 10. One part by weight of the resulting powder was mixed with 8 parts by weigh of acetone, and the resulting mixture was boiled under refluxing for one hour and filtered to obtain a filtrate A and a residue. The residue was mixed with acetone in a weight ratio of 1:8, and the resulting mixture was boiled under refluxing for one hour and filtered to obtain a filtrate B. The filtrate A and filtrate B were combined, and it was concentrated in a water bath of 70° C. and in vacuo (Rotavapor R-220, BÜCHI, Switzerland) by evaporating the solvent therefrom. The resulting concentrate was introduced to a reverse phase chromatography column (7.1 cm×90 cm) packed with Diaion® HP-20 resin (Mitsubishi, Japan) in an amount of 20 times by dry weight of the concentrate of the combined filtrate, which was then eluted with 5 bed volumes of water, 4 bed volumes of 40% ethanol and 2 bed volumes of acetone in sequence. The eluate from the elution of acetone were collected and concentrated in vacuo (Rotavapor R-220, BÜCHI, Switzerland) to dry, and then concentrated again in a water bath of 80° C. and in vacuo (40 mbar) for one hour to obtain Sample 10.
Example 9
The procedures of Example 8 were repeated to obtain Sample 11, except that the eluent of 40% ethanol was replaced by 70% ethanol. The eluate from the elution of 70% ethanol were collected and concentrated in vacuo (Rotavapor R-220, BÜCHI, Switzerland) to dry, and then concentrated again in a water bath of 80° C. and in vacuo (40 mbar) for one hour to obtain Sample 11.
Example 10
The procedures of Example 8 were repeated to obtain Sample 12, except that the powder and the residue were boiled with ethyl acetate instead of acetone.
Example 11
The procedures of Example 9 were repeated to obtain Sample 13, except that the powder and the residue were boiled with ethyl acetate instead of acetone.
Example 12
Sliced shade dried rhizomes of ginger were pulverized and screened with a sieve of mesh No. 10. One part by weight of the resulting powder was mixed with 8 parts by weigh of 95% ethanol, and the resulting mixture was boiled under refluxing for one hour and filtered to obtain a filtrate A and a residue. The residue was mixed with 95% ethanol in a weight ratio of 1:8, and the resulting mixture was boiled under refluxing for one hour and filtered to obtain a filtrate B. The filtrate A and filtrate B were combined, and it was concentrated in a water bath of 70° C. and in vacuo (Rotavapor R-220, BÜCHI, Switzerland) by evaporating the solvent therefrom. The resulting concentrate was introduced to a normal phase chromatography column packed with 20 times by weight of silica gel 60 (Merck, Germany), which was then eluted with 4 bed volumes of a mixed eluent of n-hexane:ethyl acetate=9:1, 3 bed volumes of a mixed eluent of n-hexane:ethyl acetate=6:4 and 2 bed volumes of a mixed eluent of ethyl acetate:methanol=1:1 in sequence. The eluate from the elution of n-hexane:ethyl acetate=9:1 was collected and concentrated in vacuo (Rotavapor R-220, BÜCHI, Switzerland) to dry, and then concentrated again in a water bath of 80° C. and in vacuo (40 mbar) for one hour to obtain Sample 14. Samples 15 and 16 were obtained from the elution of n-hexane:ethyl acetate=6:4, and the elution of ethyl acetate methanol=1:1 respectively by the same procedures as used in obtaining Sample 14.
Example 13
The procedures of Example 12 were repeated except that the 95% ethanol was replaced by acetone. Samples 17, 18 and 19 were obtained from the elution of n-hexane:ethyl acetate=9:1, n-hexane:ethyl acetate=6:4, and ethyl acetate:methanol=1:1 respectively.
Example 14
Sliced shade dried rhizomes of ginger were pulverized and screened with a sieve of mesh No. 10. One part by weight of the resulting powder was mixed with 8 parts by weigh of 95% ethanol, and the resulting mixture was boiled under refluxing for one hour and filtered to obtain a filtrate A and a residue. The residue was mixed with 95% ethanol in a weight ratio of 1:8, and the resulting mixture was boiled under refluxing for one hour and filtered to obtain a filtrate B. The filtrate A and filtrate B were combined, and it was concentrated with a thin-film vacuum evaporator (CEP-L, Okawara Mfg. Co., Japan) to ⅕ of its original weight by evaporating the solvent therefrom. The resulting concentrate was introduced to a reverse phase chromatography column (34.5 cm×100 cm) packed with Diaion® HP-20 resin (Mitsubishi, Japan) in an amount of 20 times by dry weight of the concentrate, which was then eluted with 2 bed volumes of 95% ethanol and 2 bed volumes of acetone in sequence. The eluate from the elution of acetone was collected and concentrated in vacuo (Rotavapor R-220, BÜCHI, Switzerland) to dry, and then concentrated again in a water bath of 80° C. and in vacuo (40 mbar) for one hour to obtain Sample 20.
HPLC Analysis
Sample Preparation:
Accurately weigh sample into a sample bottle and dissolve with methanol to make a sample solution with concentration of 10 mg/ml. Filter the sample solution with 0.45 μm filter and analyze the filtrate with HPLC.
HPLC Condition:
Column:
Cosmosil 5C18-MS-II 4.6 × 250 mm (Nacalai
Tesque Inc.)
Guard column:
Lichrospher ® 100 RP-18e
(5 μm) (Merck)
Flow rate:
1 ml/min
Sample injection volume:
10 μl
Time (min)
0
10
80
Acetonitrile (%)
40
40
100
0.1% Phosphoric acid*
60
60
0
(%)
Column thermostat
37° C.
Detector wavelength
204 nm
*0.1% Phosphoric acid: take H 3 PO 4 (85% w/v) 2.35 ml and dilute with H 2 O to 2000 ml
The results of the HPLC analysis of Sample 1 to Sample 20 prepared above are shown in FIG. 1 to FIG. 20 . The contents of 6-gingerol and 6-shogaol in the samples (mg/g) were calculated from the HPLC analysis and are listed in Table 1 together with the extraction conditions and elution conditions used in the preparation of the samples.
TABLE 1
Content of
Content of
6-gingerol
6-shogaol
in sample
in sample
Extraction
(mg/g)
(mg/g))
Conditions
Elution Conditions
Sample 1
—
—
95% Ethanol refluxing
1) 40% EtOH after H 2 O
Sample 2
23.11
67.20
″
Acetone following 1)
Sample 3
31.14
33.76
″
2) 70% EtOH after H 2 O
Sample 4
—
68.36
″
Acetone following 2)
Sample 5
35.36
54.32
″
95% EtOH after H 2 O
Sample 6
23.85
85.18
″
70% EtOH after 20% EtOH
Sample 7
94.79
55.80
″
95% EtOH after 20% EtOH
Sample 8
—
84.53
95% Ethanol
70% EtOH after 20% EtOH
mixing in
homogenizer
Sample 9
8.98
87.15
95% Ethanol
95% EtOH after 20% EtOH
mixing in
homogenizer
Sample
39.28
67.53
Acetone refluxing
Acetone following (40% EtOH after H 2 O)
10
Sample
66.94
103.48
″
70% EtOH after H 2 O
11
Sample
38.22
66.16
EA refluxing
Acetone following (40% EtOH after H 2 O)
12
Sample
112.97
34.37
″
70% EtOH after H 2 O
13
Sample
—
—
95% Ethanol refluxing
3) n-Hexane:EA = 9:1
14
Sample
69.48
96.95
″
4) n-Hexane:EA = 6:4 following 3)
15
Sample
—
—
″
EA:MeOH = 1:1 following 4)
16
Sample
—
—
Acetone refluxing
5) n-Hexane:EA = 9:1
17
Sample
84.37
105.68
″
6) n-Hexane:EA = 6:4 following 5)
18
Sample
—
—
″
EA:MeOH = 1:1 following 6)
19
Sample
—
—
95% Ethanol refluxing
Acetone following 95% EtOH
20
“—”: indicates that there is no detectable 6-gingerol or 6-shogaol in the sample
Samples 1 to 13 and 20 were prepared by using the reverse phase chromatography column. In comparison with the HPLC analysis fingerprints shown in FIGS. 1 to 4 it can be seen that the eluate from the elution of 40% ethanol contains compounds which are more polar than 6-gingerol (Sample 1), the eluate from the elution of 70% ethanol contains compounds which are more polar than 6-gingerol, and 6-gingerol and 6-shogaol (Sample 3), and the eluate from the elution of acetone contains the remaining relatively less polar compounds (Sample 2 and Sample 4). It can be seen from FIG. 6 and FIG. 7 that more peaks can be seen in the right side when 95% ethanol is used as the eluent in contrast to 70% ethanol. Same trend can be observed in FIGS. 8 and 9 as in FIGS. 6 and 7 , where the extraction conditions are different. The fingerprints shown in FIGS. 10 and 12 are similar to those shown in FIG. 2 , where the extraction conditions are different but the elution conditions are the same. The fingerprints shown in FIGS. 11 and 13 are similar to those shown in FIG. 3 , where the extraction conditions are different but the elution conditions are the same. Sample 20 contains mostly the less polar compounds and no detectable 6-gingerol and 6-shogaol as shown in FIG. 20 , which indicates that 95% ethanol eluent has eluted most of the relatively more polar compounds including 6-gingerol and 6-shogaol from the reverse phase chromatography column. Samples 13 to 15 are similar to Samples 16 to 19 in the HPLC analysis ( FIGS. 13 to 19 ), where the extraction conditions are different but the elution conditions to the normal phase chromatography column are the same. Sample 14 (Sample 16) contains mostly the non-polar compounds and no detectable amount of 6-gingerol and 6-shogaol as shown in FIG. 14 ( FIG. 16 ) by using the eluent of n-hexane:ethyl acetate=9:1, and Sample 15 (Sample 17) contains significant amounts of 6-gingerol and 6-shogaol by using the eluent of n-hexane:ethyl acetate=6:4.
1. Anti-Microbial Test
Minimum inhibitory concentration (MIC) of sample on Helicobacter pylon was determined by the agar dilution method [Malanosk G. J. et al. Effect of pH variation on the susceptibility of Helicobacter pylori to three marcolide antimicrobial agents and temafloxacin. Eur. J. Clin. Microbial Infect Dis. 12: pp. 131-133, 1993.]. The test substance was dissolved and serially diluted in DMSO to desired stock concentrations. For each concentration tested, a 0.01 ml aliquot is added to a 48-well plate containing 0.99 ml of Columbia agar base (Oxoid, England) supplemented 7% defibrinated rabbit blood. The inoculum of Helicobacter pylori (ATCC 43504) is prepared by suspending in brain heart infusion broth to a density of 5×10 5 CFU/ml. The final maximal concentration of DMSO is 1% and the initial test substance concentration is 300 μg/ml. The plates are incubated at 35° C. for 72 hours in the microaerophilic condition (Mixed gas N 2 85%, CO 2 10% and O 2 5%) and then visually examined and scored positive (+) for inhibition of the colonies growth or negative (−) for no effect upon growth colonies. Vehicle-control and gentamicin are used as blank and positive controls, respectively. Each concentration is evaluated in duplicate. The results are shown in Table 2.
TABLE 2 Minimum inhibitory Samples concentration (MIC, μg/ml) Sample 1 —* Sample 2 30 Sample 3 30 Sample 4 30 Sample 5 —* Sample 6 30 Sample 7 30 Sample 8 30 Sample 9 30 Sample 10 30 Sample 11 30 Sample 12 100 Sample 13 10 Sample 14 30 Sample 15 10 Sample 16 30 Sample 17 30 Sample 18 10 Sample 19 300 Sample 20 10 Gingerol 10 Shogaol 10 *Minimum inhibitory concentrations (MIC) of Sample 1 and Sample 5 on Helicobacter pylori are higher than 300 μg/ml.
2. Helicobacter pylori -Induced Gastric Ulcer
Effects of samples on Helicobacter pylori -induced gastric ulcer were evaluated as described previously [Marchetti, M., Arico, B., Burroni, D., Figura, N., Rappuoli, R. and Ghiara, P. Development of a mouse model of Helicobacter pylori infection that mimics human disease. Science 267: 1655-1658, 1995.]. Groups of 5 male CD-1 (Crl.) derived mice weighing 24±2 g were fasted for 18 hours prior to intragastric inoculation of clinical isolated Helicobacter pylori in suspension at 3.2×10 9 colony formation units/0.4 ml/mouse. Test samples and vehicle (2% CMC, 10 ml/kg) were each administered orally to test animals, starting one hour after the Helicobacter pylori inoculation, dosing twice daily (10:00 am and 4:00 pm) for 7 consecutive days. Omeprazole (1 mg/kg) and clarithromycin (10 mg/kg), in combination, were used for the positive control agents and administered orally to test animal once daily for 7 consecutive days under the same schedule. Eight days after infection, all animals were fasted overnight, sacrificed and stomachs dissected along the greater curvature. Gastric ulceration scored at four levels according to the degree of hemorrhage and severity of ulcerative lesions:
0=normal appearance
1=mild red spots
2=moderate red spots and/or hemorrhage spots
3=marked hemorrhage spots
Percentage inhibition on Helicobacter pylori -induced gastric ulcer was calculated as follows:
(Scores of vehicle group−Scores of test group)/(Scores of vehicle group)×100%
The results are shown in Table 3.
TABLE 3
Percentage inhibition
on Helicobacter
Samples
Dose
pylori - induced gastric ulcer
Vehicle
10 ml/kg
0
Sample 1
300 mg/kg
17
Sample 2
300 mg/kg
66
Sample 3
300 mg/kg
83
Sample 4
300 mg/kg
73
Sample 5
300 mg/kg
50
Sample 6
300 mg/kg
64
Sample 7
300 mg/kg
71
100 mg/kg
57
Sample 8
300 mg/kg
57
Sample 9
300 mg/kg
57
Sample 10
300 mg/kg
47
Sample 11
300 mg/kg
73
Sample 12
300 mg/kg
67
Sample 13
300 mg/kg
73
Sample 14
300 mg/kg
58
Sample 15
300 mg/kg
67
Sample 16
300 mg/kg
58
Sample 17
300 mg/kg
58
Sample 18
300 mg/kg
75
Sample 19
300 mg/kg
65
Sample 20
100 mg/kg
83
30 mg/kg
75
10 mg/kg
67
3 mg/kg
50
6-Gingerol
35 mg/kg
25
Omeprazole and
1 mg/kg + 10 mg/kg
83
Clarithromycin
Only Sample 1 is less effective than 6-gingerol in treating gastric ulcer induced by Helicobacter pylori among the samples prepared in the above examples. Sample 20 is the most effective, which has 83%, 75%, 67% and 50% inhibition on Helicobacter pylori -induced gastric ulcer at dosages of 100 mg/kg, 30 mg/kg, 10 mg/kg and 3 mg/kg, respectively.
Although the present invention has been described with reference to specific details of certain embodiments thereof, it is not intended that such details should be regarded as limitations upon the scope of the invention except as and to the extent that they are included in the accompanying claims. Many modifications and variations are possible in light of the above disclosure.
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The present invention discloses a new use of a potent product extracted from rhizomes of Zingiber officinale in treating a disease associated with Helicobacter pylori such as gastritis, gastric ulcer or duodenal ulcer in a patient. The potent product is prepared by a process including the steps of a) preparing a crude extract from rhizomes of Zingiber officinale , said crude extract comprising 6-gingerol and 6-shogaol; b) introducing the crude extract to a reverse phase chromatography column, and eluting the column with a first eluent having a polarity lower than water to obtain a first potent fraction or a second eluent having a polarity lower than that of the first eluent to obtain a second potent fraction. Preferably, the second potent fraction is substantially free of both 6-gingerol and 6-shogaol.
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CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application makes reference to, and claims priority to and the benefit of, United States provisional application Ser. No. 60/224,733 filed Aug. 11, 2000.
INCORPORTATION BY REFERENCE
[0002] The above-referenced U.S. provisional application Ser. No. 60/224,733 is hereby incorporated herein by reference in its entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0003] N/A
BACKGROUND OF THE INVENTION
[0004] Current data communication systems rarely approach highest possible rate, i.e., the rate corresponding to Shannon channel capacity. For example, voiceband modems complying with ITU-T recommendation V.90 employ uncoded modulation for downstream transmission. The nominal downstream rate of 56 kbit/s is thereby almost never achieved, although under practical channel conditions the capacity rate can exceed 56 kbit/s.
[0005] The difference between the signal-to-noise ratio (SNR) required to accomplish a given rate with a given practical coding and modulation scheme and the SNR at which an ideal capacity-achieving scheme could operate at the same rate is known as “SNR gap to capacity”. At spectral efficiencies of 3 bit per signal dimension or higher, uncoded modulation with equiprobable PAM (pulse amplitude modulation) and QAM (quadrature amplitude modulation) symbols exhibit an SNR gap of 9 dB at a symbol error probability of 10 −6 . In the case of V.90 downstream transmission, the SNR gap can correspond to a rate loss of up to 12 kbit/s.
[0006] This overall 9 dB gap is generally comprised of a “shaping gap” portion and a “coding gap” portion. The “shaping gap” portion (approximately 1.5 dB) is caused by the absence of constellation shaping (towards a Gaussian distribution). The remaining “coding gap” portion (approximately 7.5 dB) stems from the lack of sequence coding to increase signal distances between permitted symbol sequences.
[0007] Two different techniques are used, generally in combination, to reduce the overall 9 dB gap. The first technique addresses the “coding gap” portion, and uses one of several coding techniques to achieve coding gains. One of these techniques is trellis-coded modulation. More recent techniques employ serial- or parallel-concatenated codes and iterative decoding (Turbo coding). These latter techniques can reduce the coding gap by about 6.5 dB, from 7.5 dB to about 1 dB.
[0008] Once a coding gain is achieved, the second technique, referred to as shaping, can be used to achieve an even further gain. This type of gain is generally referred to as a shaping gain. Theoretically, shaping is capable of providing an improvement (i.e., shaping gain) of up to 1.53 dB.
[0009] Two practical shaping techniques have been employed in the prior art to achieve shaping gains, namely, trellis shaping and shell mapping. With 16-dimensional shell mapping, such as employed in V.34 modems, for example, a shaping gain of about 0.8 dB can be attained. Trellis shaping can provide a shaping gain of about 1 dB at affordable complexity. Accordingly, between 0.5 and 0.7 dB of possible shaping gain remains untapped by these prior art shaping methods.
[0010] Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.
BRIEF SUMMARY OF THE INVENTION
[0011] Aspects of the present invention may be found in a method of communicating data in a communication system. The method generally comprises accepting and randomizing (scrambling) data from a source of user data, such as a computer, for example. The randomized data are accumulated until a Huffman codeword is recognized, at which time the Huffman codeword is mapped into a channel symbol. Then the channel symbol is applied to an input of a communication channel. In the field of source coding, the above operation is known as Huffman decoding.
[0012] The encoding operation described above may be combined with further channel encoding operations such as, for example, trellis coded modulation or some form of serial- or parallel-concatenated coding to achieve coding gain in addition to shaping gain. In addition, channel symbols can be modulated in various ways before they are applied to the input of the communication channel.
[0013] In one embodiment of the invention, the channel encoding operation described above is performed in combination with a framing operation to achieve transmission of data at a constant rate.
[0014] Next, on the receiver side of the communication channel, a channel symbol is received from an output of the communication channel after suitable demodulation and channel decoding. Once obtained, the channel symbol is converted into the corresponding Huffman codeword. The data sequence represented by concatenated Huffman codewords is de-randomized (descrambled) and delivered to a sink of user data.
[0015] In one embodiment of the invention, a deframing operation is performed, which provides for data delivery to the data sink at constant rate.
[0016] The method of the present invention results in a symbol constellation and a probability distribution of symbols in this constellation that exhibits a shaping gain of greater than 1 dB. The shaping gain may be, for example, 1.35 dB or 1.5 dB, depending on the specific design
[0017] In general, a communication system according to the present invention comprises a communication node that performs a “Huffman decoding” operation to generate channel symbols with a desired probability distribution.
[0018] These and other advantages and novel features of the present invention, as well as details of an illustrated embodiment thereof, will be more fully understood from the following description and drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0019] FIG. 1 is a block diagram of a generic communication system that may be employed in connection with the present invention.
[0020] FIG. 2 illustrates additional detail regarding the transmitters of FIG. 1 according to the present invention.
[0021] FIG. 3 shows shaping gain versus rate for PAM and QAM sq constellations of different sizes, in accordance with the present invention.
[0022] FIG. 4 plots shaping gains versus rate for square and lowest-energy 1024-QAM constellations, in accordance with the present invention.
[0023] FIG. 5 depicts the mean and standard deviation of the rate in bit/dimension and the shaping gain accomplished for a nominal rate of R=4 bit/dimension with QAM le constellations of different sizes, in accordance with the present invention.
[0024] FIG. 6 illustrates a 128-QAM le constellation with Huffman shaping for a nominal rate of 3 bit/dimension, in accordance with the present invention.
[0025] FIG. 7 illustrates one embodiment of a generic method for achieving constant rate and recovering from bit insertions and deletions.
[0026] FIG. 8 illustrates the probability of pointer overflow as a function of framing buffer size in accordance with the present invention.
[0027] FIG. 9 illustrates one embodiment of the design of a Huffman code in accordance with the present invention.
[0028] FIG. 10 is a block diagram of one embodiment of a communication system that operates in accordance with the method of present invention.
[0029] FIG. 11 is another embodiment of the design of a Huffman code in accordance with the present invention, when a framer/deframer is utilized.
[0030] FIG. 12 is a block diagram of another embodiment of a communication system that operates in accordance with the method of present invention, utilizing a framer/deframer.
[0031] FIG. 13 illustrates one operation of a system that employs Huffman shaping in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0032] FIG. 1 is a block diagram of a generic communication system that may be employed in connection with the present invention. The system comprises a first communication node 101 , a second communication node 111 , and a channel 109 that communicatively couples the nodes 101 and 111 . The communication nodes may be, for example, modems or any other type of transceiver device that transmits or receives data over a channel. The first communication node 101 comprises a transmitter 105 , a receiver 103 and a processor 106 . The processor 106 may comprise, for example, a microprocessor. The first communication node 101 is communicatively coupled to a user 100 (e.g., a computer) via communication link 110 , and to the channel 109 via communication links 107 and 108 .
[0033] Similarly, the second communication node 111 comprises a transmitter 115 , a receiver 114 and a processor 118 . The processor 118 , like processor 106 , may comprise, for example, a microprocessor. The second communication node 111 is likewise communicatively coupled to a user 120 (again a computer, for example) via communication link 121 , and to the channel 109 via communication links 112 and 113 .
[0034] During operation, the user 100 can communicate information to the user 120 using the first communication node 101 , the channel 109 and the second communication node 111 . Specifically, the user 100 communicates the information to the first communication node 101 via communication link 110 . The information is transformed in the transmitter 105 to match the restrictions imposed by the channel 109 . The transmitter 105 then communicates the information to the channel 109 via communication link 107 . The receiver 114 of the second communication node 111 next receives, via communication link 113 , the information from the channel 109 , and transforms it into a form usable by the user 120 . Finally, the information is communicated from the second communication node 111 to the user 120 via the communication link 121 .
[0035] Communication of information from the user 120 to the user 100 may also be achieved in a similar manner. In either case, the information transmitted/received may also be processed using the processors 106 / 118 .
[0036] FIG. 2 illustrates additional detail regarding the transmitters of FIG. 1 according to the present invention. The functions of transmitter 201 may be decomposed into those of a source encoder 203 and a channel encoder 205 . Generally, the source encoder 203 is a device that transforms the data produced by a source (such as the user 100 or user 120 of FIG. 1 ) into a form convenient for use by the channel encoder 205 . For example, the source may produce analog samples at a certain rate, such as, for example, 8000/s, as in a telephone application. The source encoder 203 then may perform the function of analog-to-digital conversion, converting each analog sample into an 8-bit binary code. The output of the source encoder 203 then would be a binary sequence of digits presented to the input of the channel encoder 205 at a rate of 8×8000=64,000 bit/s. The output of the source encoder 203 is passed to the channel encoder 205 , where the data are transformed into symbols that can be transmitted on the channel. For example, the data may be transformed using pulse-amplitude modulation (PAM), whereby successive short blocks of data bits of length N are encoded as analog pulses having one of 2 N allowable amplitudes.
[0037] In most communication systems, the data presented to the channel encoder are assumed to be completely random. This randomness is normally assured by the inclusion of a scrambler designed into the system. In the previous example of PAM, random data would lead to each 2 N of the allowable amplitudes being equally likely. That is, each of them occurs with probability 2 −N . It turns out that employing equally likely pulse amplitudes leads to a small inefficiency in the use of the power in the signal that is transmitted into the channel. In fact, as mentioned above, if the amplitude distribution can be made more nearly Gaussian, then up to 1.53 dB of transmitted power can be saved for the same level of error performance at the receiver.
[0038] Accordingly, a shaping function is provided in FIG. 2 by a shaper 207 , which alters the statistical distribution of the values presented to modulator 209 . Shaping the transmitted signal generally means controlling the distribution of transmitted signal values to make the signal appear more Gaussian in character. The shaper 207 comprises a Huffman decoder 211 and a mapper 213 . The design of the Huffman decoder 211 depends upon the characteristics of the channel.
[0039] In the Huffman decoder 211 , the sequence of scrambled binary data bits is parsed into Huffman codewords. The codewords are then mapped into modulation symbols. The Huffman code is designed to let the modulation symbols assume approximately a sampled Gaussian distribution.
[0040] Unlike trellis shaping or shell mapping, Huffman shaping is not a constant-rate-encoding scheme. Moreover, decoding errors can lead to bit insertion or deletion in the decoded binary data sequence. This may be acceptable for many systems, such as, for example, those in which variable-length packets are transmitted in burst mode with an Ethernet-like medium access protocol. In some cases, continuous transmission at constant rate is desirable, such as, for example, those involving variable-rate encoded voice and video streams over constant rate channels. A constant rate and recovery from bit insertions and deletions may be achieved, and the framing overhead may be kept to a value equivalent to a SNR penalty of ≈0.1 dB, for example, utilizing the method of the present invention.
[0041] The following mathematical foundation of Huffman shaping is based upon M-ary PAM data transmission, but the concept clearly applies to two- and higher-dimensional modulation as well.
[0042] Let A M be a symmetric M-ary PAM constellation of equally spaced symbols. Adjacent symbols are spaced by 2, and M may be even or odd (usually M will be even):
A M ={a i =−( M −1)+2 i, 0≦ i≦M −1}
e.g.: A 8 ={−7,−5,−3,−1,+1,+3,+5,+7}, A 5 ={−4,−2,0+2,+4}. (1)
[0043] If symbols are selected independently with probabilities p={p i , 0≦i≦M−1}, the symbol entropy H(p) (=rate) and the average symbol energy E(p) become:
H ( p ) = - ∑ i = 0 M - 1 p i log 2 p i bit / symbol
( p i = 1 M ∀ i : H ( p ) = H M = log 2 M ) , ( 2 ) E ( p ) = ∑ i = 0 M - 1 p i a i 2
( M - PAM , p i = 1 M ∀ i : E ( p ) = E M = M 2 - 1 3 ) . ( 3 )
[0044] Shaping gain G S (p) expresses a saving in average symbol energy achieved by choosing symbols from A M with probabilities p rather than selecting equiprobable symbols from a smaller constellation A M′ , where M′=2 H(p) (M′<M, ignoring that M′ may not be an integer):
G s ( p ) = E M ′ E ( p ) = 2 2 H ( p ) - 1 3 × E ( p ) . ( 4 )
[0045] The maximum shaping gain is obtained by the probability distribution p={tilde over (p)}, which minimizes E(p) subject to the constraints R=H(p) and
∑ i = 0 M - 1 p i = 1.
Differentiation of
J ( p ) = ∑ i = 0 M - 1 p i a i 2 + λ 1 ( - ∑ i = 0 M - 1 p i log 2 p i - R ) + λ 2 ( ∑ i = 0 M - 1 p i - 1 ) ( 5 )
with respect to the probabilities p i yields the conditions
∂ J ( p ) ∂ p i ❘ p = p ~ = a i 2 - λ 1 ln 2 ( ln p ~ i + 1 ) + λ 2 = 0 , for 0 ≤ i ≤ M - 1. ( 6 )
The parametric solution of (6), with the Lagrange multipliers λ 1 , λ 2 transformed into the new variables α,s, becomes
p ~ i = exp ( - 1 + ln 2 λ 1 ( a i 2 + λ 2 ) ) = α exp ( - s a i 2 ) , 0 ≤ i ≤ M - 1. ( 7 )
[0046] The optimum distribution {tilde over (p)} is thus found to be a Gaussian distribution sampled at the symbol values of A M . This solution can also be obtained by maximizing the rate R=H(p) subject to the constraints
E ( p ) = S and ∑ i = 0 M - 1 p i = 1.
The value of α follows from
∑ i = 0 M - 1 p i = 1.
The value of s may be chosen to achieve a given rate R≦log 2 (M) or a given average symbol energy S≦E M .
If M and R are increased, the optimum shaping gain tends towards the ultimate shaping gain G s ∞ =πe/6=1.423 (1.53 dB). This gain can be derived as the ratio of the variance of a uniform density over a finite interval and the variance of a Gaussian density, both with the same differential entropy.
[0047] One can see that (7) does not only hold for regular symmetric PAM constellations, but gives the optimum shaping probabilities for arbitrary one- and higher-dimensional symbol constellations as well.
[0048] In general, given a sequence of M-ary source symbols which occur independently with probability distribution p, a traditional Huffman coding approach encodes the source symbols into binary codewords of variable lengths such that (a) no codeword is a prefix of any other codeword (prefix condition), and (b) the expected length of the codewords is minimized.
[0049] An optimum set of codewords is obtained by Huffman's algorithm. More particularly, let a i be a source symbol that occurs with probability p i . The algorithm associates a i with a binary codeword c i of length l i such that 2 −i ≈p i . The algorithm guarantees that
∑ i = 0 M - 1 2 - l i = 1
(Kraft's inequality is satisfied with equality), and that the expected value of the codeword length,
L = ∑ i = 0 M - 1 p i l i ,
approaches the entropy of the source symbols within one bit [10]:
H ( p )≦ L<H ( p )+1. (8)
[0050] In the limit for large H(p), the concatenated Huffman codewords yield a binary sequence of independent and equiprobable zeroes and ones with rate R=L≅H(p) bit per source symbol. However, for certain probability distributions L may be closer to H(p)+1 than H(p) because of quantization effects inherent in the code construction. If H(p) is small, the difference between L and H(p) can be significant. The rate efficiency may be improved by constructing a Huffman code for blocks of K>1 source symbols. Then, (8) takes the form H(p)≦L(K)/K=L≦H(p)+1/K, where L(K) is the expected length of the Huffman codewords associated with K-symbol blocks. The code comprises M K codewords and the rate expressed in bit per source symbol will generally be within 1/K bit from H(p).
[0051] With the Huffman shaping method of the present invention, the traditional encoding approach is reversed. A Huffman code is generated for the optimum probability distribution {tilde over (p)} of the modulation symbols in a given M-ary constellation. In the transmitter, the sequence of data bits is suitably scrambled so that perfect randomness can be assumed. The scrambled sequence is buffered and segmented into Huffman codewords, as in traditional Huffman decoding. A codeword c i is encountered with probability 2 −l ≈{tilde over (p)} i and mapped into modulation symbol a i . In the receiver, when a symbol a i is detected codeword c i is inserted into the binary output stream.
[0052] For the general case of K-dimensional modulation (K=1: PAM, K=2: QAM), it is appropriate to express rates and symbol energies per dimension, while a i , {tilde over (p)} i , and l i relate to K-dimensional symbols.
[0053] The mean value {overscore (R)} h and the standard deviation σ R h of the number of bits encoded per symbol dimension become
R h = 1 K ∑ i = 0 M - 1 2 - l i l i bit / dimension ( ≈ 1 K H ( p ~ ) ) , ( 9 ) σ R h = 1 K ∑ i = 0 M - 1 2 - l i ( l i - KR h ) 2 . ( 10 )
[0054] The average symbol energy per dimension S h and the shaping gain G s h of the Huffman-shaped symbol sequence are given by
S h = 1 K ∑ i = 0 M - 1 2 - l i a i 2 energy per dimension ( ≈ 1 K E ( p ~ ) ) , ( 11 ) G s h = 2 2 R _ h - 1 3 × E h . ( 12 )
[0055] The corresponding quantities obtained with optimum shaping probabilities {tilde over (p)} will be denoted, respectively, by {tilde over (R)} and σ {tilde over (R)} (bit/dimension), {tilde over (S)} (energy per dimension), and {tilde over (G)} s (optimum shaping gain).
[0056] For numerical evaluations, uncoded modulation with M-PAM (M=2 m) and M-QAM (M=4 m) constellations have been considered. The M-QAM constellations are either square constellations M-QAM sq ={square root}{square root over (M)}−PAM×{square root}{square root over (M)}−PAM, or lowest-energy constellations M-QAM le comprising the M points in the set {(1+2i ,1+2κ), i, κεZ} nearest to the origin. The symmetries of the symbol constellations are enforced on the Huffman codes. In the PAM case, m codewords are constructed for positive symbols and then extended by a sign bit. Similarly, in the QAM case m codewords are constructed for symbols in the first quadrant and extended by two quadrant bits. The results of different numerical evaluations are depicted in FIGS. 3, 4 , and 5 .
[0057] FIG. 3 shows shaping gain versus rate for PAM and QAM sq constellations of different sizes, in accordance with the present invention. The solid curves indicate the shaping gains obtained with the optimum shaping probabilities {tilde over (p)}. Every rate in the interval 1≦R≦log 2 (M)/K can be accomplished (bit per dimension). The shaping gains vanish at R=1 (constellations reduced to BPSK or QPSK) and R=log 2 (M)/K (equiprobable M-QAM). The optimum shaping gains practically reach the ultimate shaping gain of 1.53 dB at R=4 bit per dimension for ≧32-PAM and ≧1024-QAM sq constellations. With the Huffman shaping method of the present invention, not every rate can be realized because of quantization effects in the construction of Huffman codes. For PAM, shaping gains of up to ≈1.35 dB are achieved at some rates above 3 bit per dimension. The effects of quantization are significantly reduced in the QAM cases. With ≧256-QAM sq constellations shaping gains within 0.1 dB from the ultimate shaping gain of 1.53 dB are consistently obtained at rates above 3 bit per dimension.
[0058] FIG. 4 plots shaping gains versus rate for square and lowest-energy 1024-QAM constellations, in accordance with the present invention. Minor differences occur in the region of diminishing shaping gains, at rates above 4.5 bit/dimension. The shaping gain of equiprobable 1024-QAM le (R=5 bit/dimension) is 0.2 dB.
[0059] FIG. 5 depicts the mean and standard deviation of the rate in bit/dimension and the shaping gain accomplished for a nominal rate of R=4 bit/dimension with QAM le constellations of different sizes, in accordance with the present invention. The nominal rate is at least closely achieved with Huffman shaping (with optimum shaping it is exactly achieved). The standard deviation increases with increasing constellation size to a final value of 1 bit/dimension. The optimum shaping gain and the Huffman shaping gain increase rapidly when the initial 256-QAM constellation is enlarged. The respective final shaping gains of ≈1.5 dB and ≈1.4 dB are practically achieved with M=512 (512-QAM le : 1.495 dB and 1.412 dB, 1024-QAM le : 1.516 dB and 1.432 dB).
[0060] FIG. 6 illustrates a 128-QAM le constellation with Huffman shaping for a nominal rate of 3 bit/dimension, in accordance with the present invention. The codeword lengths ranging from 5 to 12 bits are indicated for the first-quadrant symbols. {overscore (R)} h =2.975 (σ R h =0.919) bit/dimension and G s h =1.378 dB ({tilde over (G)} s =1.443 dB) are achieved. The symbol energies, optimum shaping probabilities, codeword probabilities and lengths, and the codewords of the first quadrant symbols are listed below. The codewords for the first-quadrant symbols end with 00.
TABLE 1 Huffman code words tabulated against their index i |a i | 2 {tilde over (p)} i p i h = 2 −l i l i c i 0 2 0.03872 0.03125 5 00000 1 10 0.02991 0.03125 5 10000 2 10 0.02991 0.03125 5 01100 3 18 0.02311 0.03125 5 11100 4 26 0.01785 0.01563 6 010000 5 26 0.01785 0.01563 6 001100 6 34 0.01379 0.01563 6 110000 7 34 0.01379 0.01563 6 101100 8 50 0.00823 0.00781 7 1010000 9 50 0.00823 0.00781 7 0101100 10 50 0.00823 0.00781 7 0101000 11 58 0.00636 0.00781 7 1101100 12 58 0.00636 0.00781 7 1101000 13 74 0.00379 0.00391 8 10101100 14 74 0.00379 0.00391 8 10101000 15 82 0.00293 0.00195 9 001001000 16 82 0.00293 0.00195 9 001000100 17 90 0.00226 0.00195 9 001010100 18 90 0.00226 0.00195 9 001010000 19 98 0.00175 0.00195 9 001011100 20 106 0.00135 0.00098 10 0010011100 21 106 0.00135 0.00098 10 0010011000 22 122 0.00081 0.00049 11 00100000100 23 122 0.00081 0.00049 11 00100000000 24 130 0.00062 0.00049 11 00101101000 25 130 0.00062 0.00049 11 00101100100 26 130 0.00062 0.00049 11 00101100000 27 130 0.00062 0.00049 11 00100001100 28 146 0.00037 0.00024 12 001000010100 29 146 0.00037 0.00024 12 001000010000 30 162 0.00022 0.00024 12 001011011000 31 170 0.00017 0.00024 12 001011011100
[0061] FIG. 7 illustrates one embodiment of a generic method for achieving constant rate and recovering from bit insertions and deletions. Data frames of N b bits are embedded into symbol frames of N s modulation symbols. Every sequence of bits transmitted within a symbol frame begins with a S&P (synch & pointer) field of n sp =n s +n p bits, where n s is the width of a synch subfield enables and n p is the width of a pointer subfield. The synch subfield enables the receiver to acquire symbol-frame synchronization. In principle, sending a known pseudo-random binary sequence with one bit (n s =1) in every S&P field is sufficient (as in T1 systems). The pointer subfield of the n th symbol frame expresses the offset in bits of the n th data frame from the S&P field.
[0062] With reference to FIG. 7 , in the 1 st symbol frame, the 1 st data frame follows the S&P field with zero offset. The S&P field and 1 st data frame are parsed into Huffman codewords, which are then mapped into modulation symbols indexed by 1,2,3, . . . N s . The end of the 1 st data frame is reached before the N s th modulation symbol has been determined. The data frame is padded with fill bits until the N s th modulation symbol is obtained. The 2 nd data frame follows the S&P field of the 2 nd symbol frame again with zero offset. Now the last symbol of the 2 nd symbol frame is found before the 2 nd data frame is completely encoded. The S&P field of the 3 rd symbol frame is inserted and encoding of the remaining part of the 2 nd data frame is then continued, followed by encoding the 3 rd data frame. The pointer in the S&P field indicates the offset of the 3 rd data frame from the S&P field. The 3 rd data frame can again not completely be encoded in the 3 rd symbol frame. The 4 th data frame becomes completely encoded in the 4 th symbol frame and is padded with fill bits, and so on. The pointer information in the S&P fields enables a receiver to recover from bit insertion and deletion errors.
[0063] To determine the overhead in framing bits per symbol, first let B n be the number of bits that are encoded into the N s symbols of the n th symbol frame. As mentioned above, the mean and standard deviation of the number of bits encoded per symbol dimension are R h and σ R h , respectively, as given by (9) and (10). Then B=N s KR h is the mean and σ B ={square root}{square root over (N s K)}σ R h the standard deviation of B n . For large N s , the probability distribution of B n will accurately be approximated by the Gaussian distribution
Pr ( B n = x ) ≅ 1 2 π σ B exp ( - ( x - B ) 2 2 σ B 2 ) , x = 0 , 1 , 2 , 3 , … ( 13 )
[0064] Next, let P n be the pointer value in the S&P field of the n th symbol frame. The pointer values will remain bounded if B>n sp +N b . Equivalently, the average number of fill bits per frame, n fill , is nonzero:
n fill =B− ( n sp +N b )>°. (14)
[0065] Moreover, in a practical implementation the pointer values remain limited to the values that can be represented in the n p -bit pointer subfield, i.e. 0≦P n ≦2 n p −1. Parameters are chosen such that the probability of P n >2 n p −1 becomes negligible. From FIG. 7 , one can verify the recursive relation
P n = { 0 if n sp + P n - 1 + N b ≤ B n - 1 n sp + P n - 1 + N b - B n - 1 otherwise . ( 15 )
The temporal evolution of the pointer probabilities then becomes
Pr ( P n = 0 ) = ∑ x ≥ 0 Pr ( P n - 1 = x ) Pr ( B n - 1 ≥ n sp + N b + x ) , ( 16 ) Pr ( P n = y ) = ∑ x ≥ 0 and x ≥ y - n sp - N b Pr ( P n - 1 = x ) Pr ( B n - 1 = n sp + N b + x - y ) , y = 1 , 2 , 3 , … . ( 17 )
(equation (17) changed to fit within page margins)
[0066] The steady-state distribution Pr(P=x)=Pr(P n→∞ =x) can be determined numerically (mathematically speaking, Pr(P=x) is the eigensolution of (16) and (17) associated with eigenvalue one). Pr(P=x) and Pr(P≧x) are plotted in FIG. 8 for the following case.
Lowest-energy 512-QAM, nominal rate R=4 bit/dimension Huffman code design: R h =4.015, σ R h =0.927 bit/dimension; shaping gain G s h =1.412 dB. Assume N s =512 QAM symbols/symbol, N b =4094 bit/data frame, n sp =12 (n s =1, n p =11) B=4111.36, σ B =29.66, n fill =5.36 bit/symbol frame.
[0072] The pointer field allows for a maximum pointer value of 2047. FIG. 6 shows that Pr(P>2047) is well below 10 −10 . The pointer values exhibit a Paréto distribution, i.e., log(Pr(P≧x)) decreases linearly for large x.
[0073] A framing overhead of (n sp +n fill )/N s =0.034 bit/QAM symbol is found, which is equivalent to an SNR penalty of 0.102 dB. The final net shaping gain becomes 1.412−0.102=1.310 dB.
[0074] Based on the above mathematical foundation of Huffman shaping, in one embodiment of the invention, the method of the present invention may generally comprise two parts. The first is related to the design of the Huffman code to be employed on a given channel, and the second is related to the operation of the Huffman shaper in the transmitter. While the above mathematical foundation of Huffman shaping assumes a PAM implementation; extension to higher-dimensional modulation are also possible.
[0075] FIG. 9 illustrates one embodiment of the design of a Huffman code in accordance with the present invention. The modulation scheme is characterized by parameters M, α, and s (see (7) and accompanying text above) acquired in block 901 , from which are derived the constellation levels {a i ;i=0,1, . . . , M −1} also in block 901 . The probability p i is then calculated for each a i in step 903 for i=0,1, . . . , M −1. Finally, a Huffman code for the symbols {a i } and their corresponding probabilities {p i } is constructed in block 905 .
[0076] FIG. 10 is a block diagram of one embodiment of a communication system that operates in accordance with the method of present-invention. Upon completion of the construction of the Huffman code in FIG. 9 , a Huffman shaper is employed. Referring to FIG. 10 , Huffman shaper 1001 is loaded with information from a table similar to Table 1 above. The Huffman shaper information comprises one entry for each valid Huffman codeword and a corresponding entry for the channel symbol into which that Huffman codeword is mapped. The information is also sent to the receiver, using means available in the training procedure for the system. Then Huffman shaping proceeds during data transmission.
[0077] Specifically, referring again to FIG. 10 , data source 1003 generates (typically binary, but this is not required) data symbols at an adjustable rate controlled by the Huffman shaper 1001 . The data symbols are converted to pseudo-random form in a scrambler 1005 . The Huffman shaper 1001 generally comprises two parts, namely, a Huffman parser 1007 and a mapper 1009 . The Huffman parser 1007 accumulates outputs from the scrambler 1005 , symbol by symbol (e.g., bit by bit), until it accumulates a valid Huffman codeword. This codeword forms the input to the mapper 1009 . The mapper 1009 generates the channel symbol that corresponds to the Huffman codeword and passes the channel symbol to modulator 1011 , under the control of the modulator clock 1013 . The modulator clock 1013 defines the timing of the system. If required by the modulator clock 1013 , the Huffman shaper 1001 controls the rate at which it accumulates output symbols from the scrambler 1005 , in order to meet the demands of the modulator clock 1013 .
[0078] Slicer/decision element 1015 maps the symbol received from the channel 1017 into its best estimate of the channel symbol transmitted by the remote transmitter. The Huffman encoder 1019 maps the estimated received channel symbol into a Huffman codeword, which is passed to the descrambler 1021 . The descrambler 1021 inverts the operation of the scrambler 1005 , and the resulting received sequence of data symbols is passed to the user 1023 .
[0079] The Huffman shaper 1001 is modeled as being able to control the rate at which data are input to the shaper (see reference numeral 1025 of FIG. 10 ). More colloquially, present-day communication systems often operate in an environment where a large buffer of data are available for transmission, and data can be removed from that buffer at any rate appropriate for the transmission medium. Therefore, ascribing an adjustable rate capability to the Huffman shaper 1001 does not burden the method of the present invention with functionality that is not already present in practical situations.
[0080] As described above, a system that employs Huffman shaping carries a variable number of bits per modulation symbol. Therefore channel errors can introduce data in the receiver that is incorrect bit-by-bit, and that actually may contain the wrong number of bits as well. That is, referring to FIG. 10 , if a channel symbol different from the one introduced at the input to the modulator 1011 is received at the output of the slicer/decision element 1015 , then both the bits and the number of bits passed to the Huffman encoder 1019 may be incorrect. To compensate for this potential effect, a framer/deframer may be introduced.
[0081] FIG. 11 is another embodiment of the design of a Huffman code in accordance with the present invention, when a framer/deframer is utilized. Again, a PAM implementation is assumed, but extensions to higher-dimensional modulation are also possible. Referring to FIG. 11 , the modulation scheme is characterized by parameters M,α,s,N b ,N s ,n s , and n p acquired in block 1001 , from which are derived the constellation levels {a i ;i=0,1, . . . , M −1}(block 1101 ). Parameters N b ,N s ,n s , and n p define, respectively, the number of data bits, the number of modulation symbols, the number of synch bits, and the number of pointer bits in each symbol frame. The probability p i then is calculated for each a i in block 1103 for i=0,1, . . . , M −1. Finally, a Huffman code for the symbols {a i } and their corresponding probabilities {p i } is constructed in block 1105 .
[0082] FIG. 12 is a block diagram of another embodiment of a communication system that operates in accordance with the method of present invention, utilizing a framer/deframer. Upon completion of the construction of the Huffman code in FIG. 11 , a Huffman shaper is employed. Referring to FIG. 12 , Huffman shaper 1201 is loaded with information from a table similar to Table 1 above. The Huffman shaper information consists of one entry for each valid Huffman codeword and a corresponding entry for the channel symbol into which that Huffman codeword is mapped. A framer 1203 is loaded with parameters N b ,N s ,n s , and n p . The information is also sent to the receiver using means available in the training procedure for the system. In the receiver a deframer 1205 is loaded with the same parameters, N b ,N s ,n s , and n p . Then Huffman shaping proceeds during data transmission.
[0083] Specifically, referring to FIG. 12 , data source 1207 generates data symbols at an adjustable rate controlled by the Huffman shaper 1201 . The data symbols are converted to pseudo-random form in a scrambler 1209 . The scrambler 1209 output is collected in the framer 1203 , which arranges transmitted data in groups of N b bits per symbol frame, N s modulation symbols per symbol frame, n s synch bits per frame and n p pointer bits per frame as discussed above. The Huffman shaper 1201 generally comprises of two parts, a Huffman parser 1211 and the mapper 1213 . The Huffman parser 1211 accumulates outputs from the framer 1203 , symbol by symbol, until it accumulates a valid Huffman codeword. This codeword forms the input to the mapper 1213 . The mapper 1213 generates the channel symbol that corresponds to the Huffman codeword and passes the channel symbol to the modulator 1215 under the control of the modulator clock 1217 . The modulator clock 1217 defines the timing of the system. If required by the modulator clock 1217 , the Huffman shaper 1201 controls the rate at which it accumulates output symbols from the scrambler 1209 in order to meet the demands of the modulator clock 1217 (see reference numeral 1218 in FIG. 12 ).
[0084] The slicer/decision element 1219 maps the symbol received from the channel 1221 into its best estimate of the channel symbol transmitted by the remote transmitter. The Huffman encoder 1223 maps the estimated received channel symbol into a Huffman codeword. In this embodiment, switch 1225 is in position A. The deframer 1205 is able to distinguish individual received modulation symbols by means of the demodulator clock 1227 signal from the demodulator 1229 . It uses the received symbol frame as well as the synch and pointer bits to construct a serial data stream corresponding to the output of the scrambler 1209 . This output is passed to the descrambler 1231 , which inverts the operation of the scrambler 1209 , and the resulting received sequence of data symbols is passed to the user 1233 .
[0085] In still another embodiment of the invention, the Huffman code constructed in a slightly modified fashion. This embodiment uses a one-dimensional form of the Huffman code described above. Specifically, a Huffman code is constructed for only the positive modulation symbols. After a Huffman code word has been collected in the transmitter by the Huffman decoder, the decoder uses its next input bit to define the sign of the modulation symbol corresponding to the collected Huffman code word. An inverse procedure is applied in the receiver. Again, a PAM implementation is assumed, but extension to higher-dimensional modulation is also possible.
[0086] Referring to FIG. 11 , the modulation scheme is characterized by parameters M, α, s, N b , N s ,n s , and n p acquired in block 1101 , from which are derived the constellation levels {a,; i=0,1, . . . , M −1} (block 1101 ). Parameters N b ,N s ,n s , and n p define, respectively, the number of data bits, the number of modulation symbols, the number of synch bits, and the number of pointer bits in each symbol frame. The probability p i is then calculated for each nonnegative a i in block 1103 for i=0,1, . . . , M −1. Finally, a Huffman code for the nonnegative symbols {a i } and their corresponding probabilities {p i } is constructed in block 1105 .
[0087] Upon completion of the construction of the Huffman code in FIG. 11 , a Huffman shaper is employed. Referring to FIG. 12 , Huffman shaper 1201 is loaded with information from a table similar to Table 1 above. The Huffman shaper information consists of one entry for each valid Huffman codeword and a corresponding entry for the channel symbol into which that Huffman codeword is mapped. The framer 1203 is loaded with parameters N b ,N s ,n s , and n p . The information is also sent to the receiver using means available in the training procedure for the system. In the receiver the deframer 1205 is loaded with the same parameters, N b ,N s ,n s , and n p . Then Huffman shaping proceeds during data transmission.
[0088] Specifically, data source 1207 generates data symbols at an adjustable rate controlled by the Huffman shaper 1201 . The data symbols are converted to pseudo-random form in scrambler 1209 . The scrambler 1209 output is collected in the framer 1203 , which arranges transmitted data in groups of N b bits per symbol frame, N s modulation symbols per symbol frame, n s synch bits per frame and n p pointer bits per frame, as discussed above. The Huffman shaper 1201 generally comprises two parts, the Huffman parser 1211 and the mapper 1213 . The Huffman parser 1211 accumulates outputs from the framer 1203 , symbol by symbol, until it accumulates a valid Huffman codeword. The Huffman parser 1211 then accumulates one additional input bit and appends it to the Huffman codeword. This Huffman codeword with the appended bit forms the input to the mapper 1213 . The mapper 1213 generates the channel symbol that corresponds to the Huffman codeword, and uses the appended bit to define the sign of the channel symbol. It then passes the channel symbol to the modulator 1215 under the control of the modulator clock 1217 .
[0089] The slicer/decision element 1219 maps the magnitude of the symbol received from the channel 1221 into its best estimate of the magnitude of the channel symbol transmitted by the remote transmitter. It also estimates the sign of the received symbol. The channel symbol magnitude is passed to the Huffman encoder 1223 , which maps the estimated received channel symbol magnitude into a Huffman codeword and presents the output at the A input of switch 1225 . The sign of the received symbol is presented at the B input of switch 1225 by means of connection sign information 1235 . Switch 1225 , normally in the A position; is switched to the B position after each received Huffman code word, in order to accept the sign information 1235 from the slicer/decision element 1219 . The deframer 1205 is able to distinguish individual received modulation symbols by means of the demodulator clock 1227 signal from the demodulator 1229 . It uses the received symbol frame as well as the synch and pointer bits to construct a serial data stream corresponding to the output of the scrambler 1209 . This output is passed to the descrambler 1231 , which inverts the operation of the scrambler 1209 , and the resulting received sequence of data symbols is passed to the user 1233 .
[0090] FIG. 13 illustrates one operation of a system that employs Huffman shaping in accordance with the present invention. A transmitter 1301 accepts user data (block 1303 ). The transmitter 1301 may also perform a framing operation ( 1307 ) to provide a means to recover from possible errors that may be introduced in the channel.
[0091] The transmitter 1301 then implements Huffman shaping. Specifically, the transmitter 1301 accumulates source data until a Huffman codeword is recognized (block 1309 ), and then maps the resulting Huffman codeword into a channel symbol (block 1311 ). The transmitter then performs a modulation operation (block 1313 ), which optionally includes sequence coding to increase the signal distances between permitted symbol sequences. Finally, the modulated signal is applied to the input of the communications channel (block 1315 ).
[0092] The receiver 1317 accepts the received signal from the channel output (block 1319 ), and demodulates it (block 1321 ). Demodulation generally includes such operations as timing tracking and equalization. The received signal is then subjected to a decision operation, which may optionally include sequence decoding (block 1323 ). The Huffman shaping (blocks 1309 and 1311 ) is inverted by applying the received signal to the input of a Huffman encoder (block 1325 ). The receiver 1317 then performs a deframing operation (block 1327 ), and communicates the received data to the user (block 1331 ).
[0093] Based on the foregoing discussion, it should be apparent that in one embodiment of the invention, once data is received from a data source, the sequence of binary data bits is randomized by a scrambling operation and bits are mapped into channel symbols such that the channel symbols occur with a probability distribution suitable for achieving shaping gain. This is accomplished by accumulating scrambled data bits until a Huffman codeword is recognized, at which time the Huffman codeword is mapped into a channel symbol. Then the channel symbol is applied to the input of a communication channel. The probability of recognizing in the scrambled data sequence a particular Huffman codeword of length L bits is 2 −L . Hence, the channel symbol associated with that particular Huffman codeword will be transmitted with probability 2 −L . Note that this channel encoding operation via Huffman codes corresponds in the field of source coding to Huffman decoding.
[0094] In one embodiment of the invention, the channel encoding operation described above is performed in combination with a framing operation to achieve transmission of data at a constant rate. In addition, channel symbols can be modulated in various ways before they are applied to the input of the communication channel.
[0095] Next, on the receiver side of the communication channel a channel symbol is obtained at the demodulator output. The channel symbol is converted into the corresponding Huffman codeword. The sequence of bits represented by concatenated Huffman codewords is descrambled and delivered to the data sink. The described channel decoding operation corresponds in the field of source coding to Huffman encoding.
[0096] In one embodiment of the invention, a deframing operation is performed, which provides for data delivery to the data sink at constant rate. In addition, the deframing operation limits the effect of channel demodulation errors, which can cause a temporal shift of the received binary data sequence. This shift can occur when a channel symbol is erroneously decoded whose associated Huffman codeword differs in length from the Huffman codeword associated with the correct channel symbol.
[0097] The method of the present invention results in a symbol constellation and a probability distribution of symbols in this constellation that exhibits a shaping gain of greater than 1 dB. The shaping gain may be, for example, 1.35 dB or 1.5 dB, depending on the specific design. More specifically, for PAM constellations, shaping gains of up to ≈1.35 dB are achieved for some rates. For QAM constellations, shaping gains within 0.1 dB from the ultimate shaping gain are consistently obtained for rates of >3 bit per dimension.
[0098] In general, a communication system according to the present invention comprises a communication node that performs a Huffman decoding operation to generate channel symbols with a desired probability distribution.
[0099] Many modifications and variations of the present invention are possible in light of the above teachings. Thus, it is to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as described hereinabove.
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In a communication system, Huffman coding techniques are used to obtain shaping gains for an improvement in data transmission rates. More particularly, a novel method of Huffman shaping is described that achieves a shaping gain of greater than 1 dB. The shaping gain results in a higher data rate transmission in a communication system where transmitted power is constrained.
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BACKGROUND
The present application relates to grounding assemblies for electronic equipment and particularly relates to grounding assemblies for use with outdoor electronic equipment that is subject to being damaged by lightning. An example of such electronic equipment is the electronic controllers used on irrigation systems, such as those used on golf courses and the like. Irrigation systems include numerous sprinkler heads located throughout a property which are turned on and off by a plurality of solenoid valves located at or near the valves. The solenoid valves have control boards which are typically connected to a central control computer and a power source by wires buried under ground. Lightning striking the ground far from a particular control board can induce voltage spikes in the wires leading to the control board that can destroy the board. Lightning arrestors are typically incorporated in such equipment to prevent this but for such arrestors to protect the equipment adequately they must have an effective connection to ground.
It is the responsibility of the installer to connect all electronic irrigation equipment to earth ground in accordance with Article 250 of the National Electrical Code (NEC.) Grounding, bonding, and shielding components will, at a minimum, include the following items. Earth grounding must be done with grounding electrodes that are UL listed or manufactured to meet the minimum requirements of Article 250.52 of the 2008 edition of the NEC. At the very minimum, the grounding circuit will include a copper clad steel ground rod, a solid copper ground plate installed under ground and in contact with a suitable amount of an earth contact material, such as the carbon backfill products sold under the trademarks PowerSet or PowerFill by Loresco International of Hattiesburg, Miss. This is the minimum requirement for supplementary grounding of any electronic equipment.
FIGS. 1 and 2 illustrate the components required for supplementary grounding. The electronic equipment, such as an irrigation controller, is shown at 10 . A ground rod 12 has a minimum diameter of ⅝ inches and a minimum length of 10 feet. The ground rod 12 is driven into the ground in a vertical position or an oblique angle not to exceed 45 degrees at a location 10 feet from the electronic equipment 10 , the ground plate 14 , or the wire 16 connecting the ground plate 14 to the equipment 10 , as shown in FIG. 1 . A 6 AWG solid bare copper wire 18 (about 12 feet long) is connected at 19 to the ground rod 12 by the installer using an exothermic welded connection, such as that provided by the Cadweld® GR1161G “One-Shot” welding kit available from Erico International Corporation of Solon, Ohio. The wire 18 shall be connected to the electronic equipment's ground lug.
The copper ground plate 14 must meet the minimum requirements of Article 250.52(A)(7) of the 2008 NEC. It is made of a copper alloy intended for grounding applications and has minimum dimensions of 4 in.×96 in.×0.0625 in. A 25-foot continuous length (no splices allowed unless using exothermic welding process) of 6 AWG solid, round, bare copper wire 16 is attached to the plate by the manufacturer using an approved welding process. This wire 16 is also connected to the electronic equipment's ground lug. In the past the round wire 16 has sometimes been replaced with a braided copper strap for connecting the electronic equipment to the ground plate 14 . But braided copper straps have complicated geometry that contributes to higher inductance characteristics. The ground plate 14 is to be installed to a minimum depth of 30 inches, or below the frost line if the frost line is lower than 30 inches, at a location 8 feet from the electronic equipment 10 and underground wire 18 . A suitable amount of earth contact material 20 must be spread so that it surrounds the copper grounding plate 14 evenly along its length within a 6 inch wide trench. Salts, fertilizers, bentonite clay, cement, coke, carbon, and other chemicals are not to be used to improve soil conductivity because these materials are corrosive and will cause the copper electrodes to erode and become less effective with time.
The grounding circuit components are to be installed in straight lines, to the extent possible, with no sharp turns. To prevent the electrode-discharged energy from re-entering the underground wires, all electrodes are installed away from such wires. The spacing between any two electrodes is as shown in FIGS. 1 and 2 , so that they don't compete for the same soil.
The earth-to-ground resistance of this circuit is to be no more than 10 ohms. If the resistance is more than 10 ohms, additional ground plates and earth contact material are to be installed in the direction of an irrigated area at a distance of 10 feet, 12 feet, 14 feet, etc. It is required that the soil surrounding copper electrodes be kept at a minimum moisture level of 15% at all times by dedicating an irrigation station at each controller location. The irrigated area should include a circle with a 10-foot radius around the ground rod 12 and a rectangle measuring 1-foot×24-feet around the plate 14 . All underground circuit connections are to be made using an exothermic welding process by utilizing products such as the Cadweld® “One-Shot” kits. Solder cannot be used to make these connections.
The above grounding circuit is referred-to as supplementary/auxiliary grounding in the NEC. For safety reasons the NEC requires that all supplementary grounds be bonded to each other and to the service entrance ground (power source). This is also the recommended practice of IEEE Standard 1100-1999. Note that this is in addition to the equipment ground, which is commonly referred to as “the green wire.” The black (line or hot), white (neutral), and green wires must always be kept together in a trench, conduit, tray or the like. The bonding conductors are to be 6 AWG solid bare copper unless the system power conductors are larger than 1/0 AWG, in which case they are to be 4 AWG solid bare copper. All splices to the bonding conductors shall be made using an exothermic welding process.
SUMMARY
The present invention concerns an improved grounding assembly that is used to ground outdoor electronic equipment, such as irrigation controllers in a fixed irrigation system, for the purpose of providing a discharge path for the lightning induced voltage spikes. The grounding assembly comprises a ground plate and an electrically conductive strap. The conductive strap is electrically connected to the ground plate and electrically connectable to the electronic equipment. The conductive strap has a length, width and thickness. The width of the conductive strap is greater than the thickness. In a preferred embodiment the thickness of the conductive strap is about the same as the thickness of the ground plate and the strap has a generally rectangular cross section. Since flat conductors have lower inductance characteristics than round conductors, this reduces the inductance from the electronic equipment to the ground plate. Lightning follows the path of least inductance. Accordingly, the conductive strap of the present invention improves the ability of the grounding assembly to discharge the energy from lightning and thereby protect the electronic equipment.
These and other desired benefits of the invention, including combinations of features thereof, will become apparent from the following description. It will be understood, however, that a device could still appropriate the claimed invention without accomplishing each and every one of these desired benefits, including those gleaned from the following description. The appended claims, not these desired benefits, define the subject matter of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic plan view of the layout of a prior art ground assembly.
FIG. 2 is a schematic side elevation view of a prior art ground assembly.
FIG. 3 is a schematic circuit diagram of the system in which the ground assembly of the present invention may be incorporated.
FIG. 4 is a front elevation view of a printed circuit board for an irrigation controller, a ground wire connecting the wire to a ground bar, and a conductive strap and bonding wires.
FIG. 5 is a front elevation view of the ground bar.
FIG. 6 is a section taken along line 6 - 6 of FIG. 5 , with the conductive strap also shown in its slot.
DETAILED DESCRIPTION
FIG. 3 is a circuit diagram of the system in which the ground assembly of the present invention may be used. The electronic equipment is shown generally at 10 . In this case it is shown as an irrigation controller but it will be understood that other types of electronic equipment could utilize the ground assembly of the present invention. The controller is mounted on a pad 22 on the ground 24 . The controller receives electric power from power lines which in this case are labeled black for line or hot, white for neutral and green or bare for equipment ground. The power lines are connected to a service entrance indicated schematically at box 26 . A power source from the utility company indicated schematically at 27 connects to a fuse or circuit breaker 28 . A ground bus bar 30 is also provided, with the white and green lines connected thereto. An earth ground 32 is provided by the utility company.
The enclosure for the electronic equipment may also house a ground bar shown schematically in FIG. 3 at 34 . Details of the ground bar will be described below. The ground bar 34 connects to a ground wire 36 , a conductive strap 38 , and bonding conductors 40 and 42 . Bonding conductor 40 joins the utility earth ground 32 , while bonding conductor 42 extends to other controllers. The conductive strap 38 connects the ground bar 34 to the ground plate 14 . The ground wire 36 is fixed to a ground lug 46 on the electronic equipment for connecting to the ground bar 34 . In the illustrated embodiment the ground wire continues from the bar 34 to the ground rod 12 . Alternately, a separate wire could be used for connecting the ground bar to the ground rod.
Further details are shown in FIG. 4 . The irrigation controller includes at least two printed circuit boards, one of which is shown at 44 . Board 44 is a lightning protection board that contains lightning arrestors. It will be understood that other possible arrangements of the various circuit boards are possible and that the lightning protection components could be incorporated in boards having multiple functions, such as an output board or a communication system boards. It is connected to other boards (not shown) that contains the circuit elements for interpreting control signals from a central control computer and actuating one or more solenoid valves in accordance with the control signals. The lightning protection board 44 has components designed to protect it and the second board from lightning induced spikes coming in through any wire connected to the controller. The lightning protection board 44 has a ground lug 46 affixed thereto. A connector block 43 receives the underground wires. Sets of fuses 45 and chokes 47 are provided. The chokes have high inductance which prevents spikes associated with the high frequency lightning strikes on the ground from passing to the second board. The high impedance caused by the chokes redirects such spikes to the ground lug 46 and conductive strap 38 . The ground lug 46 has a set screw connector 48 attached to it for receiving the ground wire 36 . The ground wire extends into and through the ground bar 34 . It is held fixed in the ground bar by a set screw 50 . The conductive strap 38 fits through a slot in the ground bar 34 . Two set screws 52 hold the strap 38 in the slot. FIG. 4 also shows the bonding wires 40 , 42 attached to the ground bar 34 . A set screw 54 is used on each bonding wire to retain it in the ground bar.
The conductive strap 38 has a length L as seen in FIG. 4 . It also has a width W and a thickness T (see FIG. 6 ). The width W is greater than the thickness T. Preferably, the thickness T is about the same as the thickness of the ground plate 14 . For reference purposes only and not by way of limitation, the width W may be about ½″ and the thickness T may be about 1/16″. In the preferred embodiment shown the strap has a generally rectangular cross section but it could be otherwise so long as the width is greater than the thickness. This configuration affords a reduction in the inductance of the strap, as compared to a round wire. The lower inductance provides superior dissipation of energy from lightning strikes at high frequencies.
FIGS. 5 and 6 illustrate details of the ground bar 34 . It is an elongated bar made of electrically conductive material, such as aluminum, although other materials could be used. A series of internally-threaded set screw openings 56 are formed in the front face 58 . A slot 60 extends through the center of the bar, all the way from the top face 62 to and through the bottom face 64 . Slot 60 is sized to receive the conductive strap 38 as described above. On either side of the slot 60 there is a pair of bores parallel to the slot. These similarly extend all the way through the ground bar 34 . Bores 66 , 68 are on one side of the slot, while bores 70 , 72 are on the other side. Bore 66 receives the ground wire 36 . Bores 70 and 72 receive the bonding wires 40 , 42 , respectively. Bore 68 is an unused spare in the illustrated version. It could be used if it were desired to separate the ground wire 36 into two separate wires. That is, one wire could extend from the lug 46 to bore 66 and a second, separate wire could extend from the bore 68 to the ground rod 12 .
As can be seen from the above description, the present invention has several different aspects, which are not limited to the specific structures shown in the attached drawings and which do not necessarily need to be used together. Variations of these concepts or structures may be embodied in other structures without departing from the present invention as set forth in the appended claims. For example, the cross section of the conductive strap could vary from rectangular. It could have an oval cross section in which the major axis is greater than the minor axis. Or it could have a modified oval cross section with curved side edges and flat top and bottom surfaces. This could be made by starting with a round wire and squeezing it to flatten opposite sides of the wire. Preferably, the cross section has at least portions of the top and bottom surfaces that are planar. Most commonly these planar portions will also be parallel to one another, although they could have a non-parallel relationship. Although a relatively flat cross section is shown in the drawings, the cross section of the conductive strap could have any shape that has a lower inductance than a fully circular cross section.
In a further alternate construction the conductive strap and ground plate could be integrally formed from a single piece of copper. This would obviate the need to weld the two pieces together.
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A grounding assembly for electronic equipment provides a discharge path for the energy arising from lightning strikes. A conductive strap connects the ground lug of the equipment to a ground plate buried in the earth. The conductive strap has a length, width and thickness, with the width being greater than the thickness. This reduces the inductance of the conductor from the controller to the ground plate, thereby enhancing the ability of the grounding assembly to dissipate energy from lightning strikes.
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INCORPORATION BY REFERENCE
This application herein incorporates by reference the following applications: U.S. application Ser. No. 09/240,751, which was filed on Jan. 29, 1999, U.S. application Ser. No. 60/117,784, filed Jan. 29, 1999, U.S. application Ser. No. 09/449,505, entitled “Discharging a Superconducting Magnet”, filed Nov. 24, 1999; U.S. application Ser. No. 09/449,436, entitled “Method and Apparatus for Controlling a Phase Angle”, filed Nov. 24, 1999; U.S. application Ser. No. 60/167,377, entitled “Voltage Regulation of Utility Power Network”, filed Nov. 24, 1999; U.S. application Ser. No. 09/449,375, entitled “Method and Apparatus for Providing Power to a Utility Network”, filed Nov. 24, 1999; and U.S. application Ser. No. 09/449,435, entitled “Electric Utility System with Superconducting Magnetic Energy Storage”, filed Nov. 24, 1999.
BACKGROUND OF THE INVENTION
This invention relates to electric power utility networks including generating systems, transmission systems, and distribution systems serving loads.
Utility power systems, particularly at the transmission level, are primarily inductive, due to the impedance of transmission lines and the presence of numerous transformers. Further, many of the largest loads connected to the utility power system are typically inductive. Large motors used, for example, in lumber mills, rock crushing plants, steel mills, and to drive pumps, shift the power factor of the system away from the desired unity level, thereby decreasing the efficiency of the power system. Because of the daily and hourly load variations, it is necessary to change the amount of compensation applied to counteract the effects of these changing inductive loads
One approach for providing compensation to the system is to connect one or more large shunt capacitor banks to provide a capacitive reactance (e.g., as much as 36 MVARs) to the system in the event of a contingency (i.e., a nonscheduled event or interruption of service) or sag in the nominal voltage detected on the utility power system. By selecting the proper amount of capacitance and connection location, these capacitor banks provide a level of control of the line voltage or power factor. Mechanical contactors are typically employed to connect and switch the capacitor banks to compensate for the changing inductive loads.
SUMMARY OF THE INVENTION
The invention features a system and approach for minimizing the step voltage change experienced by the utility customer as well minimizing transients imposed on the fundamental waveform of a normal voltage carried on a utility power network when a reactive power source (e.g., capacitor bank) is instantaneously connected to the utility power. The reactive power source is adapted to transfer reactive power of a first polarity (e.g., capacitive reactive power) to the utility power network.
In one aspect of the invention, the system includes a reactive power compensation device configured to transfer a variable quantity of reactive power of a second, opposite polarity to the utility power network, and a controller which, in response to the need to connect the shunt reactive power source to the utility power network, activates the reactive power compensation device and, substantially simultaneously, causes the shunt reactive power source to be connected to the utility power network.
In another aspect of the invention, a method of providing reactive power compensation from a reactive power source to a utility power network carrying a nominal voltage includes the following steps. A change in magnitude in the desired nominal voltage on the utility power network is detected, and such change results in voltage deviating outside of a utility specified acceptable range. In response to detecting the change in the desired nominal voltage, the reactive power source is connected to the utility power network to provide reactive power compensation of a first polarity. For a predetermined first duration, reactive power compensation of a second opposite polarity is provided to the utility power network in a period substantially coincident with connecting the reactive power source to the utility power network.
By transferring reactive power of a second, opposite polarity to the network when the switch is closed, the magnitude of a potentially large step-like change in reactive power introduced from the reactive power source is offset for a period of time, thereby minimizing potential transients which would normally be imposed over the fundamental utility waveform carried on the utility power network. These transients are caused by the generally step-like change in voltage when the reactive power source is connected to the utility power network. Although there are many forms of transients, which can be imposed on the utility waveform, such transients are typically in the form of oscillatory “ringing” imposed over the fundamental waveform. Such ringing can cause among other problems, false switching of power devices and overvoltage failures. In addition, the sudden step voltage change induced by switching the utility reactive device can disrupt sensitive industrial control systems and processes. An overvoltage failure can be catastrophic to customers. In essence, the system “softens” the sharp, step-like introduction of reactive energy from the reactive power source.
Embodiments of these aspects of the invention may include one or more of the following features.
In a preferred embodiment, the controller is configured to activate the reactive power compensation device to transfer reactive power compensation of the first polarity to the utility power network prior to connecting the shunt reactive power source to the utility power network. As stated above, providing reactive power compensation of the second, opposite polarity to the utility power network opposes the abrupt step like introduction to the utility power network of reactive power of the first polarity delivered by the shunt reactive power source. Providing reactive power compensation of the first polarity prior to connecting the shunt reactive power source to the utility power network, allows a significantly greater magnitude of change in reactance when the reactive power compensation of the second polarity is introduced. Furthermore, the reactive power compensation device provides additional voltage support to the system prior to the shunt reactive power source being connected to the utility power network.
The reactive power compensation of the first polarity is generally provided for a duration between 1 and 2 seconds.
The impedance of a utility power network is primarily inductive, due to the long line lengths and presence of transformers. Thus, in a preferred embodiment, the reactive power source is a capacitor bank and during particular time periods the reactive power compensation device provides inductive power compensation.
The system and method are used with a utility power network that includes a transmission network and a distribution network electrically connected to the transmission network. The distribution network has distribution lines, with the reactive power source normally connected to the transmission network and the reactive power compensation device connected to the distribution network of the utility power network and proximally to each other.
Typically, reactive power compensation is switched on when the nominal voltage drops below 98% and switched off when voltage exceeds 102% of the nominal voltage. Moreover, the allowable step change in the voltage due to switching of the reactive compensation device is typically limited to about 2% at the transmission voltage level
In certain applications, after providing reactive power compensation of the second opposite polarity, a second stage of reactive power compensation of the first polarity is provided in conjunction with the reactive power source providing reactive power compensation. In other words, the reactive power compensation device supplements the reactive power provided by the reactive power source.
For example, in an emergency mode operation, the voltage on the utility power network may have dropped significantly. In this case, the inverter will operate continuously to provide reactive power in conjunction with the capacitor bank. If the inverter is only operated for a relatively short, emergency mode, the inverter may be operated in overload fashion to provide a maximum amount of reactance. Alternatively, the inverter can be operated in a steady state mode, to provide a lower reactance level over a longer, indefinite duration.
These and other features and advantages of the invention will be apparent from the following description of a presently preferred embodiment and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram representation of a voltage recovery device and switched capacitor bank connected to a utility power network.
FIG. 2 is a block diagram of a portion of reactive power compensation device of FIG. 1 connected to a distribution line.
FIG. 3 is a flow diagram illustrating the general steps for operating the voltage recovery device.
FIG. 4 is a graph showing the output of the reactive compensation device.
FIG. 5 is a graph showing the utility voltage characteristic as a function of time using the reactive compensation device.
DETAILED DESCRIPTION
Referring to FIG. 1 , a reactive power compensation system 30 is shown connected in shunt with a distribution line 20 of utility power network. Distribution line 20 is shown connected to a transmission line 18 of the transmission line network through a first transformer 22 a , which steps down the higher voltage (e.g., greater than 25 kV carried on transmission line 18 to a lower voltage, here 6 kV. A second transformer 22 b steps down the 6 kV to a voltage suitable for a load 24 , here 480 V.
Reactive power compensation system 30 includes an energy storage unit 32 , an inverter system 44 , and a controller 60 , which is used in conjunction with a transmission capacitor bank 31 . Energy storage unit 32 may be in a part of a D-SMES module, which is capable, together with inverter system 44 , of delivering both real and reactive power, separately or in combination, to distribution line 20 . In this embodiment, D-SMES module could be sized at 3.0 MVA and with inverter 44 is capable of delivering an average of 2 MWatts for periods as long as 400 milliseconds, 7.5 MVA for a full second, and 3.0 MVAR of reactive power indefinitely. Further details relating to the operation and construction of the D-SMES module can be found in co-pending application, Ser. No. 09/449,435, filed on Nov. 24, 1999, by Paul Frederick Koeppe, Arnold P. Kehrli, John A. Diaz de Leon III, Donald L. Brown, Warren Elliott Buckles ahd Douglas C. Folts, and entitled “Electric Utility System with Superconducting Magnetic Energy Storage”.
As will be described in greater detail below, inverter 44 , under the intelligent control of controller 60 , serves to transfer reactive power to and from the utility power network. In particular, during the initial period in which capacitor bank 31 begins delivering reactive power to the utility power network, inverter 44 provides an inductive reactance to counteract the abrupt, step-like introduction of capacitive reactive power from capacitor bank 31 on the utility power network. Furthermore, inverter 44 can be controlled to provide additional voltage support to the system prior to capacitive bank 31 being connected to the utility power.
Capacitor bank 31 provides a capacitive reactance (e.g., as much as 36 MVARs) to the system in the event of a contingency (i.e., a nonscheduled event or interruption of service) or sag in the nominal voltage detected on the utility power system. Capacitive banks suitable for use with reactive power compensation system 30 are commercially available from ABB, Zurich Switzerland. Further details relating to capacitor banks used in conjunction with superconducting energy storage systems can be found in U.S. Pat. No. 4,962,354, U.S. Pat. No. 5,194,803, and U.S. Pat. No. 5,376,828, all of which are incorporated herein by reference.
Capacitor bank 31 is coupled to transmission line 18 through a relay switch 35 and a switchgear unit 39 , which provide over-current protection and to facilitate maintenance and troubleshooting of capacitor bank 31 . A protective fuse 41 is connected between switchgear 39 and transmission line 18 .
Referring to FIG. 2 , inverter system 44 converts DC voltage from energy storage unit 32 to AC voltage and, in this embodiment, includes four inverter units 46 . In general, inverter 44 can act as a source for leading and lagging reactive power. In general, inverter can only source real power from energy storage unit 32 for as long as real power is available from the energy storage unit. However, inverter 44 can source reactive power indefinitely assuming the inverter is operating at its nominally rated capacity. Thus, inverter 44 can provide reactive power without utilizing power from energy storage unit 32 . Further details regarding the arrangement and operation of inverter 44 can be found in co-pending application, Ser. No. 09/449,435, filed on Nov. 24, 1999, by Paul Frederick Koeppe, Arnold P. Kehrli, John A. Diaz de Leon III, Donald L. Brown, Warren Elliott Buckles and Douglas C. Folts, and entitled “Electric Utility System with Superconducting Magnetic Energy Storage”.
Each inverter unit 46 is capable of providing 750 KVA continuously and 1.875 MVA in overload for one second. The outputs of each inverter unit 46 are combined on the medium-voltage side of the power transformers to yield the system ratings in accordance with the following table.
Power Flow Value Duration MVA delivered, leading or 3.0 Continuously lagging MVA delivered, leading or 7.5 1-2 seconds in event of lagging, overload condition transmission or distribution fault detection Average MW delivered to utility 2.0 0.4 seconds in event of (for an exemplary D-SMES transmission or distribution fault module). detection
Each inverter unit 46 includes three inverter modules (not shown). Because inverter units 46 are modular in form, a degree of versatility is provided to accommodate other system ratings with standard, field proven inverter modules. A level of fault tolerance is also possible with this modular approach, although system capability may be reduced. Each inverter module is equipped with a local Slave Controller that manages local functions such as device protection, current regulation, thermal protection, power balance among modules, and diagnostics, among others. Inverter units and modules are mounted in racks with integral power distribution and cooling systems.
Inverter system 44 is coupled to distribution line 20 through step-down transformers 50 and switchgear units 52 . Each power transformer 50 is a 6 kV/480 V three-phase oil filled pad mount transformer having a nominal impedance of 5.75% on its own base rating. The power transformers are generally mounted outdoors adjacent to the system enclosure with power cabling protected within an enclosed conduit (not shown). As is shown in FIG. 1 , a fuse 53 is connected between step-down transformer 50 and distribution line 20 .
Each switchgear unit 52 provides over-current protection between power transformers 50 and inverter units 46 . Each of the four main inverter outputs feeds a circuit breaker rated at 480 V, 900 A RMS continuous per phase with 45 kA interruption capacity. Switchgear units 52 also serve as the primary disconnect means for safety and maintenance purposes. The switchgear units are generally mounted adjacent to the inverter unit enclosures.
Referring again to FIG. 1 , system control unit 60 has a response time sufficient to ensure that the transfer of power to or from energy storage unit 30 occurs at a speed to address a fault or contingency on the utility system. In general, it is desirable that the fault is detected within 1 line cycle (i.e., {fraction (1/60)} second for 60 Hz, {fraction (1/50)} second for 50 Hz). In one embodiment, the response time is less than 500 microseconds.
With reference to FIGS. 3-5 , the operation of controller 60 and inverter 44 is described in conjunction with an exemplary contingency occurring on the utility power network. At the outset, the nominal voltage of the utility power system is monitored (step 200 ). For example, the nominal voltage on transmission line 18 is sensed either directly or from a remote device. FIG. 5 shows that in this particular example the voltage is detected as being 98% of nominal value at t=0. When the nominal voltage has dropped below a predetermined threshold value (e.g., here 98%), an input control signal is transmitted to controller 60 which, in turn, transmits a trigger signal 73 (at point 75 of FIG. 5 ) to activate inverter 44 (step 202 ) and begin ramping inverter reactive output from zero to full overload rating in 0 to 2 seconds (represented by reference 85 , FIG. 4 ). When full leading output of the inverter has been achieved, a signal is sent to close mechanical contactor 35 (step 204 ).
Referring to FIG. 4 , prior to enabling switch 35 to operate, inverter system 44 is activated to ramp upward to provide the maximum amount of capacitive reactance available, for example, +7.5 MVARs). Because inverter is not intended to provide this maximum reactive power for more than a few seconds, inverter system 44 is operated in an overload mode. Simultaneous with the closing of contactor 35 (at point 77 of FIGS. 4 and 5 ), inverter 44 is controlled to now provide the maximum available inductive reactance, for example, −7.5 MVARs (step 206 ). The time period between step 202 and setup 206 is set based on the known characteristics of mechanical contactor 35 or can be learned by controller 60 which monitors the change in voltage. As shown in FIG. 5 , inverter 44 alone has increased the voltage by 1.45% prior to energizing capacitor bank 31 .
In a second step, when contactor 35 closes, capacitor bank 31 injects capacitive reactance, here 36 MVARs, onto the utility power system. During this period in which capacitive bank 31 is switched into the circuit, the voltage increases an additional 0.98%. The inductive reactance provided by inverter 44 cancels in part the capacitive reactance from capacitor bank 31 . This mitigates possible “ringing” caused by the rapid introduction of reactance onto the sagging utility power signal were capacitor bank 31 be allowed to unleash its fall 36 MVARs onto the utility power network.
In a third step—immediately after contactor 35 is closed—the inductive reactance provided by inverter 44 ramps down (at point 79 ) until the inverter no longer generates reactive power (at point 81 ). During this third step the voltage increases an additional 1.14%. At this point, the sole reactance being introduced to the utility power network is from capacitor bank 31 .
As can be seen from FIG. 5 , this approach softens the otherwise step-like injection of capacitive reactance from capacitor bank 31 (represented by dashed line 83 ). Moreover, the fall 3.6% voltage increase provided by capacitor bank 31 has been accomplished without an abrupt step-like injection of reactive power. Furthermore, the fall 3.6% voltage increase is provided in three steps, none of which exceeds the 2% limit that utilities generally require.
However, in circumstances in which additional capacitive reactance, beyond that provided by capacitive bank 31 , would be desirable, inverter 44 can be controlled to provide supplemental capacitive reactance.
Referring to FIG. 4 , inverter 44 is controlled to provide additional capacitive reactance in an “emergency overload mode”. It is important to note that during this second capacitive reactance period 87 , capacitor bank 31 is also providing capacitive reactance to the utility power network. In this overload mode, inverter 44 provides the maximum reactance available. In an alternative application, where capacitive reactance is desired over longer periods (perhaps, indefinitely), inverter 44 may be controlled to provide a lower level (e.g., 2-3 MVARs) in a steady state mode of operation. In applications where real power does not need to be supplied to the utility power network, the invention would be implemented without energy storage unit 32 .
Further details relating to the control of inverter 44 to adjust the phase angle of the reactance, can be found in co-pending applications, Ser. No. 09/449,436, filed on Nov. 23, 1999, by Douglas C. Folts and Warren Elliott Buckles, entitled “Method and Apparatus for Controlling a Phase Angle,” and in Ser. No. 60/167,377, filed on Nov. 24, 1999, by Thomas Gregory Hubert, Douglas C. Folts and Warren Elliott Buckles, entitled “Voltage Regulation of Utility Power Network”.
It is also important to appreciate that the invention is equally applicable in situations when capacitor bank 31 is removed from the utility power network. That is, a similar step voltage would decrease occur when capacitor bank is switched off. In this case, the process described above in conjunction with FIGS. 3-5 is reversed.
Other embodiments are within the scope of the claims. For example, in the embodiment described above in conjunction with FIGS. 1 and 2 , a D-SMES unit was discussed as being used to provide the real and reactive power needed to recover the voltage on the transmission network. However, it is important to appreciate that other voltage recovery devices capable of providing both real and reactive power, including flywheels, batteries, an energy storage capacitive systems bank, compressed gas energy sources, and fuel cell systems (e.g., those that convert carbon based fuels into electricity) are also within the scope of the invention.
Still other embodiments are within the scope of the claims. For example, the invention can also be used in conjunction with other approaches for minimizing transient effects. For example, the invention can complement those approaches using zero-switching techniques, such as that described in U.S. Pat. No. 5,134,356, which is incorporated herein by reference. The utility power network described above in conjunction with FIG. 1 included distribution lines connected to a load 24 .
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The invention features a system and approach for minimizing the step voltage change as seen by the utility customer as well minimizing transients imposed on the fundamental waveform of a normal voltage carried on a utility power network when a reactive power source (e.g., capacitor bank) is instantaneously connected to the utility power. The reactive power source is adapted to transfer reactive power of a first polarity (e.g., capacitive reactive power) to the utility power network. The system includes a reactive power compensation device configured to transfer a variable quantity of reactive power of a second, opposite polarity to the utility power network, and a controller which, in response to the need to connect the shunt reactive power source to the utility power network, activates the reactive power compensation device and, substantially simultaneously, causes the shunt reactive power source to be connected to the utility power.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns a method for exchange of data between two electronic entities.
2. Description of the Related Art
In the framework of the exchange of data between two electronic entities (which data can be represented in the form of electrical signals in these electronic entities, for example in memories carried by these electronic entities), it has been proposed in particular to implement short range communication (also known as near field communication (NFC)), as described in patent application WO 2007/121 791. The expression short range generally refers to a range of less than 1 m, for example a range of the order of 50 cm, or even 20 cm.
The RFID technology is frequently used to provide such short range communication, and consists in providing a remote power feed by means of a reader to an electronic circuit (for example carried by a “tag”, but possibly also by any other object, for example a mobile telephone) which can then communicate with the reader and transmit to it data intended in particular (in the most standard uses of this technology) to identify the product or the person bearing the tag.
Although the limitation of the interaction between the reader and the electronic circuit to the near field generated by the reader (which is in practice a magnetic field) might initially seem problematic, it is to the contrary seen as an advantage of this technology, because communication is initiated by bringing the electronic circuit and the reader close together and thus, typically, stems from an intentional action on the part of the bearer of the electronic circuit.
The patent application WO 2006/115 842 describes a use of this type, for example.
At present, each electronic circuit designed to use the RFID technology is designed with a particular object (i.e. with a view to a particular service) and in that context holds only data relating to the service concerned (for example the code associated with the user's account in the aforementioned document WO 2006/115 842). If the electronic circuit is carried by a telephone, the data relating to the service is thus stored in a memory of the telephone, for example. This solution is lacking in flexibility, however, and for example obliges a user to obtain in advance a plurality of tags each configured to work with each service that they wish to enjoy. Generally speaking it is impossible to access services for which the electronic circuit is not configured.
SUMMARY OF THE INVENTION
To improve on this state of affairs, the invention proposes a method of exchanging data between a first electronic entity and a second electronic entity, characterized by the following steps:
initiating communication between the first electronic entity and the second electronic entity subsequently to bringing the first and second electronic entities closer together; in consequence of said initiation, transmitting an application from the second electronic entity to the first electronic entity; storing said application in the first electronic entity.
Thus there is provision for automatically installing (with installation possibly monitored by the user) of a process for storing an application that enables access to functions associated with the second electronic entity (the reader in the examples given hereinafter), even though there is originally no provision for this in the first electronic entity (mobile object).
For example, the step of initiating communication in practice comprises the following steps:
remote power feeding of the first electronic entity by the second electronic entity; sending a communication set-up message from the first electronic entity to the second electronic entity.
There can also be a step, executed in consequence of the initiation and prior to the transmission of the application, of verifying the presence of said application in a memory of the first electronic entity. Transmission is then implemented only if necessary, when the application is not present in the first electronic entity.
In a first embodiment, the verification step comprises the following steps:
the second electronic entity sending the first electronic entity a command designating said application; searching a memory of the first electronic entity for said application.
In a second embodiment, the verification step comprises the following steps:
the first electronic entity sending a list of applications present in a memory of the first electronic entity; the second electronic entity determining the presence of said application in said list.
There can further be the following steps, executed as a consequence of the initiation and prior to the transmission of the application:
displaying on the first electronic entity information indicating transmission; awaiting validation; transmitting the application in the case of validation.
The process can also comprise a step of the first electronic entity preparing a request for loading of said application, in which case execution of the preparation step can be conditional on receiving authorization of a user.
The above two solutions enable the user to retain control over storage of the application despite the automatic launching of the process.
The application obtained by the loading process is used for example during exchanges between the first electronic entity and the second electronic entity.
In this context, the following steps can be implemented:
the first electronic entity executing the application in order to determine a response; the first electronic entity sending the response to the second electronic entity.
The transmission of the application and the sending of the response are both effected in the examples described here by communication between short range communication means respectively equipping the first and second electronic entities, which constitutes a particularly advantageous embodiment.
Alternatively, the transmission of the application could nevertheless be obtained by communication between high throughput wireless (i.e. contactless) interfaces of the first and second electronic entities, such as WUSB or BLUETOOTH interfaces. These interfaces are generally separate from the short range, here NFC, interface.
The application is thus exchanged quickly between the electronic entities.
In this context, the application relates to the second electronic entity (the reader in the following examples) since it participates in effecting exchanges between the two electronic entities. The application could nevertheless alternatively have no link with these exchanges; as such, it could for example be a question of an application the execution of which is effected autonomously in the first electronic entity, as in the case of a game.
The first electronic entity is a portable (or pocket) electronic entity, for example, such as a mobile telephone or a portable information medium (of the USB key type) and the communication is short range wireless communication.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
Other features and advantages of the invention will become more apparent in the light of the following description, given with reference to the appended drawings, in which:
FIG. 1 represents one possible context for implementation of the invention;
FIG. 2 represents the execution of exchanges between the devices of FIG. 1 in a first embodiment of the invention;
FIG. 3 represents the execution of such exchanges in a second embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 represents one example of a context in which the invention can be implemented.
Such a context includes in particular a portable object 10 (here a mobile telephone) and a reader 30 .
The mobile telephone 10 and the reader 30 can exchange data via short range communication (for example NFC) means.
Those short range communication means include in particular an NFC module 24 cooperating (for example via a bus) with a microprocessor 12 of the mobile telephone and connected to an NFC antenna 26 also carried by the mobile telephone 10 .
The reader 30 also includes an antenna 34 through which a current flows under the control of a control module 32 so as to generate a magnetic field 36 for supplying power to and communicating with objects situated in the vicinity of the reader 30 (generally in an area extending to less than one meter from the reader, for example to less than approximately 20 cm therefrom, the range being in practice from 1 cm to 10 cm with the technologies widely used at present).
As already indicated, the mobile telephone 10 includes a microprocessor 12 adapted to manage the various functions of the mobile telephone 10 , in particular the interface with the user of the mobile telephone 10 (for example by means of a keypad and a screen, not shown). To this end in particular, a read-only memory 16 and a random-access memory 14 are associated with the microprocessor 12 .
The read-only memory 16 stores in particular sequences of instructions intended to be executed by the microprocessor 12 in order to implement methods within the mobile telephone 10 , in particular the methods proposed by the invention and described hereinafter.
The random-access memory 14 stores parameters or instructions necessary for the execution of the methods mentioned above.
Note further that, as well as or instead of one of the memories 14 , 16 , there can be provided a non-volatile rewritable memory for storing some of the data or instructions mentioned above.
The mobile telephone 10 finally includes a cellular telecommunications module 18 adapted to exchange data (which can represent the voice of a speaker, for example, but can equally be data or instructions sent to the microprocessor 12 , for example) with a base station 70 of a cellular telephone network (in particular via an antenna 20 with which the mobile telephone 10 is equipped and an antenna 72 of the base station).
The mobile telephone 10 finally includes a cellular telecommunications module 18 adapted to exchange data (which can represent the voice of a speaker, for example, but can equally be data or instructions sent to the microprocessor 12 , for example) with a base station 70 of a cellular telephone network (in particular via an antenna with which the mobile telephone 10 is equipped and an antenna 72 of the base station).
A server 50 stores in particular applications intended for the mobile telephone 10 in the framework of its exchanges with the reader 30 , as explained hereinafter. In the embodiment considered here, this server 50 is connected to the reader 30 or to the base station 70 (and in practice possibly to both these elements), for example by means of cable connections, possibly via the Internet.
There is described now with reference to FIG. 2 a first example of a method for exchanging data between the various elements described hereinabove in accordance with the teachings of the invention.
This method is used after the portable object 10 (here a mobile telephone, as already indicated) is brought near the reader 30 (here to within less than 20 cm of it, as indicated above), which normally corresponds to the user of the mobile telephone 10 wishing to use functions associated with this reader 30 .
Because the telephone 10 and the reader 30 have been brought close together, the telephone 10 (and in particular its NFC antenna 26 ) enters the magnetic field 36 generated by the reader 30 , which instigates a remote power feed to the module 24 and consequently its initialization in the step E 200 .
Note that the NFC module 24 with which the mobile telephone 10 is equipped can alternatively be supplied with power by the mobile telephone 10 (in which case there is no remote power feed by the reader 30 ) but can be reinitialized (step E 200 ) as soon as the antenna 26 enters the electromagnetic field 26 of the reader 30 .
The NFC module 24 then initiates communication with the reader 30 , for example by sending it in the step E 202 information indicating its presence in the field 36 of the reader 30 . Communication can be initiated as described in the ISO 14443 standard, for example.
Thus in the step E 204 the reader 30 detects the portable object 10 (which here is a mobile telephone) and consequently sends a command to it in the step E 206 . The command is an element of the implementation of the function that the user is seeking when they bring the telephone 10 close to the reader 30 , as mentioned above. It is an APDU command according to the ISO 7816 standard, for example. Alternatively, the command need not itself participate in the function that the user is seeking but instead include as a parameter the application associated with the function that the user is seeking.
The telephone receives the command via the NFC link: the command passes through the NFC module 24 to the microprocessor 12 that is its destination.
Then in the step E 208 the microprocessor 12 verifies if the code (for example the executable or interpretable code, i.e. the application) for executing this command (or part of this command, for example a subroutine) is stored in one of the memories 14 , 16 (or possibly in a memory of the microcircuit card 22 ). The code (i.e. the application) is a series of independent instructions (in practice at least three instructions), stored in executable or interpretable form, for example, or even in the form of a source program to be compiled: these applications are for example formulated in the languages Javacard, Javascript, Java, assembler, C++.
This verification is effected, for example, by consultation of a table that contains, for each command that can be envisaged, an indicator of the presence of the application associated with that command in the memory of the mobile telephone 10 and, in the event that the application is present, its storage address.
It is equally possible in the embodiments described hereinafter to provide for storing in the same table, but this time with no application in the memory, data that is useful for obtaining the application (for example information to the effect that the application must be obtained from the reader 30 itself as in the present embodiment, or the coordinates of the server 50 —for example a number usable by the cellular telephone system or an http address—with a view to downloading, as in the second embodiment described hereinafter with reference to FIG. 3 ).
If so, the microprocessor executes the application in order to execute the command as described hereinafter in the step E 236 .
If not, the microprocessor 12 prepares an application loading request and to this end first requests the microcircuit card module 22 to sign and encrypt this loading request (step E 210 ).
The loading request includes a description of the command (such as a command number), for example, and possibly parameters such as elements describing the technical specifications of the mobile telephone 10 and possibly the http address of the server 50 .
As already indicated, the loading request is sent to the microcircuit card 22 for signing and encryption (step E 212 ) using a key stored in the microcircuit card and the microcircuit card 22 then sends the encrypted and signed request back to the microprocessor 12 (step E 214 ).
The sending E 216 and/or encryption of the request can be conditional upon verification (here by the card 22 ) of the presence of a right by the microcircuit card 22 and/or by an authorization (possibly with authentication) of the user of the mobile telephone 10 , for example by selection of an item from a menu or pressing a particular key, or by entering and verifying a personal code (of PIN (Personal Identification Number) type).
Alternatively, the user can be requested to provide such authorization at the time of loading or installing the application.
Alternatively the operations of encryption and/or authentication of the user can be carried out by the mobile telephone 10 (instead of the microcircuit card 22 ).
The encrypted and signed request can then be sent over the NFC link (i.e. in practice via the NFC module 24 ) to the reader 30 , which thus receives the encrypted and signed request in the step E 218 .
The reader 30 and primarily its control module 32 can thus in step E 220 verify the signature in order to be sure of the identity of the object 10 (or of the microcircuit card 22 or the bearer of the object, and thus where appropriate verify authorization of the latter to receive the application) and decrypt the request, for example by means of a key associated with the private key stored in the microcircuit card 22 of the portable object 10 .
Following the above operations, the control module 32 of the reader 30 can proceed to process the decrypted request and to this end obtains a copy of the application to be transmitted, for example by reading a storage device associated with the reader 30 (such as a hard disk connected locally or integrated into the reader 30 ) or by means of a connection to the server 50 mentioned above and holding the application (in which case the connection between the reader 30 and the server 50 is preferably a secure connection, especially if the connection between the reader 30 and the server 50 uses at least in part a public network such as the Internet). Note that in this latter case the reader 30 sending the encrypted and signed request directly to the server 50 can be envisaged instead and that verification of the signature and decryption are effected by the server 50 .
In the embodiment described here, the copy of the application obtained by the reader 30 in the step E 222 is moreover a version that has been encrypted and signed, for example using a private key held by the publisher of the application.
The encrypted and signed application is sent from the reader 30 to the mobile telephone 10 via the NFC link in the step E 224 and the microprocessor 12 thus receives the encrypted and signed application via the NFC module 24 in the step E 226 . As already indicated, the application could instead be exchanged via other interfaces of the telephone 10 and the reader 30 , for example high throughput wireless interfaces.
Then in the step E 228 the microprocessor 12 sends the version of the application received to the microcircuit card module 22 for verification of the signature and decryption of the latter version.
In the step E 230 the microcircuit card module 22 then proceeds to verify the signature (by means of the public key associated with the private key of the publisher of the application, and decrypts the version of the application received from the reader 30 by means of a secret key, the aforementioned keys being obtained by the microcircuit card 22 by connecting to a server, for example, via the Internet, for example, and stored in a memory of the microcircuit card 22 or the mobile telephone 10 , for example a nonvolatile memory).
In the step E 232 the microcircuit card module 22 sends back the decrypted application (when the signature has been verified, of course; if not, the application received is not executed).
Thus the microprocessor 12 receives the application from the microcircuit card module 22 and stores it in the random-access memory 14 (or alternatively in the microcircuit card 22 ), which enables it to be installed in the step E 234 , possibly with other, associated operations.
Alternatively the application can be installed (and thus in particular stored) in a nonvolatile memory of the mobile telephone. In this case a list of the applications installed in this way can be kept, for example in the telephone, with the date of the last use of each of them, for example in order to delete the application least recently when the memory space allocated is full and a new installation is required.
Thus the microprocessor 12 can execute the command requested by the reader 30 in the step E 236 using the application that has just been received by the method described above (“no” response in step E 208 ) or that is already stored in the mobile telephone 10 (“yes” response in step E 208 ).
As indicated above, the command (or the application designated as a parameter in the command in the variant already referred to above) is part of the implementation of a function required by the user of the mobile telephone and in this context defines a particular exchange protocol between the reader 30 and the mobile telephone 10 , for example.
In this context, the mobile telephone 10 sends back a response following on from execution of the command (or the application designated by it) to the reader 30 (step E 238 ), which response the reader receives in the step E 240 .
FIG. 3 represents a second example of the method of exchanging data between the elements from FIG. 1 .
As in the above example, communication between the portable object 10 and the reader 30 is engaged by virtue of the remote power feeding of the short range communication means of the portable object 10 as a result of moving the latter closer to the reader 30 , which leads to initialization of communication between the portable object 10 and the reader 30 in the step E 400 .
In the example described here, the portable object then sends a list of commands available in the portable object (step E 402 ) via these short range communication means. Note that the portable object 10 here sends the list of commands available without any prompting by the reader 30 .
Alternatively, the list of commands available in the portable object 10 could be sent to the reader 30 only at the request of the reader 30 , for example by the reader 30 sending a request for communication of the list or if the portable object 10 receives a command from the reader 30 .
In the step E 404 the reader 30 receives the list of commands or applications available in the portable object 10 .
The reader 30 can then itself determine if a command or application intended for the portable object 10 is contained in this list of the commands available (step E 406 ) or if an application necessary for execution of the command is contained in the list.
If so, the reader 30 can send the command to the portable object 10 (in the step E 418 described hereinafter).
If not, the loading into the portable object 10 of the application corresponding to the command required by the reader 30 constitutes a preliminary step to sending this command and the reader 30 launches a process of loading the application from the step E 408 onward, as described hereinafter.
Note that in a variant that can be envisaged the determination of the availability of the command in the portable object 10 could be effected by sending a request to the portable object, verifying the presence of the associated application in the portable object 10 as in the previous embodiments, and the portable object 10 sending the reader 30 information indicating the availability or non-availability of the command in the portable object 10 .
As indicated above, if it is determined that loading of the application associated with a command is necessary before execution thereof, there follows the step E 408 in which in the present embodiment the reader 30 sends the portable object 10 a request for agreement to such loading.
The portable object 10 receives this request for agreement and requests the agreement of the user, for example, as shown in the step E 410 (typically by displaying a corresponding message for the attention of the user and awaiting a response from the user via a keypad of the portable object 10 ).
If the user refuses loading (“no” response in the step E 410 ), communication between the reader 30 and the portable object 10 is terminated, for example, because a command from one to the other cannot be executed (step E 412 ).
On the other hand, if the user agrees to loading (“yes” response in the step E 410 ), for example by pressing a predetermined real or virtual key (menu) and/or by entering a personal code, the portable object 10 sends back to the reader 30 information indicating that agreement (step E 414 ).
Note that requesting the user's agreement in the manner described above is one possible embodiment, but that other variants can be envisaged: in particular, the portable object 10 could agree to loading as a function of a parameter stored in the portable object 10 and indicating that such loading is authorized.
Alternatively the user's agreement could be requested before installing the application, i.e. immediately after the step E 416 described below.
After reception of the agreement for loading in the step E 414 , the reader 30 proceeds to send the application associated with the command in the step E 415 , which application the reader 30 holds beforehand, for example on a local hard disk (or in any other storage means, such as a memory, for example) or is obtained via a connection (possibly a secure connection) to the remote server 50 , as indicated above with reference to the first embodiment.
The application is then received by the portable object 10 in the step E 416 and installed therein (i.e. primarily stored in a memory of the portable object 10 , typically the memory 14 ).
Once the application has been sent in the step E 415 , and possibly after a time delay (or alternatively on reception of confirmation by the object 10 that the application has been installed), the reader can proceed to send the required command in the step E 418 .
The portable object 10 receives the command in the step E 420 and executes it using the application in its memory (where appropriate because it was loaded in the step E 415 as described above).
The result of executing this application is sent in the step E 422 in the form of a response to the reader 30 , which receive this information in the step E 424 .
The previous examples are only possible embodiments of the invention, which is not limited to them. In particular, a variant can be envisaged in which the mobile telephone equipped with the NFC module functions as the reader. Moreover, the features and variants of the various embodiments described hereinabove can be combined.
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A method of exchanging data between a first electronic entity and a second electronic entity includes the following steps:
initiating (E 400 ) communication between the first electronic entity and the second electronic entity subsequently to bringing the first and second electronic entities closer together; in consequence of the initiation, transmitting (E 415 ) an application from the second electronic entity to the first electronic entity; storing (E 416 ) the application in the first electronic entity.
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BACKGROUND
[0001] 1. Technical Field
[0002] The present disclosure relates to a surgical implant for treating obesity in a patient. More particularly, the present disclosure relates to a surgical implant for constricting the stomach of a patient to treat obesity in a patient.
[0003] 2. Background of Related Art
[0004] A variety of different approaches are known for the treatment of obesity in a patient. These approaches can be of the non-surgical variety, e.g., dieting, or of the surgical variety, e.g., gastric bypass, small bowel bypass etc. Where non-invasive non-surgical procedures such as dieting rely on the will power of a patient and may not be effective, invasive surgical procedures such as bypass surgery can be risky and have undesirable side effects. As such, less invasive surgical devices for constricting or reducing the capacity of the digestive tract, e.g., the stomach have been developed. These devices include gastric bands which are positioned about the stomach to constrict the stomach and devices such as inflatable balloons for reducing the reservoir capacity of the stomach. Each of these types of devices produce a sense of satiety in a patient to reduce the patient's desire to ingest food.
[0005] Although the above-identified devices have had some success, improvements to these devices would be desirable.
SUMMARY
[0006] In accordance with the present disclosure, a gastric restrictor assembly is provided which includes a housing, a valve assembly and an attachment mechanism. In one embodiment, the valve assembly is supported within the housing and includes a first member, a second member and a plurality of vanes which define a throughbore. The plurality of vanes are pivotally supported about a pivot member on the first member and the first member is fixedly secured within the housing. The second member is rotatably secured to the first member and includes a plurality of cam members. Each of the cam members is positioned within a slot formed in one of the plurality of vanes. The second member is movable in relation to the first member to move the cam members within the slots to effect pivoting of the vanes about the pivot members. The second member is movable between a first position and a second position to move the vanes between a first position defining a minimum throughbore diameter and a second position defining a maximum throughbore diameter.
[0007] In one embodiment, the first member includes a first ring or annular member and the second member includes a second ring or annular member. The second ring member includes gear teeth positioned at least partially about its periphery. An actuator is rotatably supported on the housing and includes gear teeth positioned to mesh with the gear teeth of the second ring member to move the second ring member between its first and second positions.
[0008] In one embodiment, the attachment mechanism includes a plurality of arcuate fastening members or hoops and a drive ring. Each hoop can include a pointed or sharpened tip and an arcuate body having a plurality of threads formed thereon. The drive ring includes an inner surface having a plurality of gear teeth and an outer surface having a helical thread. The fastening members are positioned at least partially within the housing such that each fastening member extends through or is positioned to extend through an opening in the housing. The helical thread of the drive ring is positioned to engage the plurality of the threads on the arcuate body of each fastening member such that upon movement of the drive ring in relation to the fastening member, each fastening member is moved between a retracted position and a deployed or advanced position.
[0009] In one embodiment, the inner surface of the drive ring includes gear teeth which are positioned to mesh with the gear teeth of a drive ring actuator. The drive ring actuator is actuable to effect rotation of the drive ring in relation to the plurality of fastening members.
[0010] In one embodiment, an attachment mechanism actuation tool is provided to actuate the drive ring actuator and a valve assembly adjustment tool is provided to actuate the second member of the valve assembly. Both the attachment mechanism actuation tool and the valve assembly adjustment tool can be configured and dimensioned for transoral actuation of the attachment mechanism and the valve assembly, respectively.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Various embodiments of the presently disclosed gastric restrictor assembly are disclosed herein with reference to the drawings, wherein:
[0012] FIG. 1 is a top perspective view of one embodiment of the presently disclosed gastric restrictor assembly;
[0013] FIG. 2 is a top perspective, exploded view of the valve assembly and attachment mechanism of the gastric restrictor assembly shown in FIG. 1 ;
[0014] FIG. 3 is a cross-sectional view taken along section lines 3 - 3 of FIG. 1 ;
[0015] FIG. 4 is a bottom perspective view of the second member of the valve assembly of the gastric restrictor assembly shown in FIG. 3 ;
[0016] FIG. 5 is a top cross-section view of the gastric restrictor assembly shown in FIG. 1 illustrating the throughbore of the assembly in its maximum diameter position;
[0017] FIG. 6 is a top cross-sectional view of the gastric restrictor assembly shown in FIG. 1 illustrating the throughbore of the valve assembly in its minimum diameter position; and
[0018] FIG. 7 is a side view of the gastric restrictor assembly shown in FIG. 1 attached to an internal wall of the stomach with a portion of the stomach cutaway.
DETAILED DESCRIPTION OF EMBODIMENTS
[0019] Embodiments of the presently disclosed gastric restrictor assembly and its method of use will now be described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views.
[0020] FIG. 1 illustrates one embodiment of the presently disclosed gastric restrictor assembly shown generally as 10 . Gastric restrictor assembly 10 includes an annular housing 12 which defines a thoughbore 13 and supports a valve assembly 14 and an attachment mechanism 16 . In one embodiment, housing 12 is formed from half-sections 12 a and 12 b which are fastened together to enclose valve assembly 14 and attachment mechanism 16 . Actuators 18 and 20 are positioned on a top surface of housing 12 to facilitate operation of valve assembly 14 and attachment mechanism 16 , respectively, as will be described in further detail below.
[0021] Referring to FIGS. 2-4 , valve assembly 14 includes actuator 18 , a first member 22 , a second member 24 ( FIG. 3 ) and a multiplicity of vanes 26 . First and second members 22 and 24 may be in the form of first and second rings which define a throughbore 28 which is substantially coaxial with throughbore 13 of housing 12 . First member 22 is rotatably fixed to a bottom inner wall of housing 12 such as by pins 30 . A plurality of pivot members 32 are spaced about first member 22 . Each pivot member 32 is positioned and dimensioned to be received in a hole 34 formed in a respective vane 26 such that vanes 26 are pivotally supported on first member 22 . Each vane 26 includes an elongated slot 36 . It is envisioned that pivot members 32 may be formed integrally with housing 12 and first member 22 can be eliminated from assembly 10 .
[0022] Second member 24 is rotatably mounted to first member 22 . In one embodiment, second member 24 includes first and second half-sections 24 a and 24 b which are fastened about first member 22 . First member 22 includes an annular recess 40 which is dimensioned to receive an annular rib 42 formed about an inner wall of second member 24 ( FIG. 3 ). Positioning of rib 42 within annular recess 40 of first member 22 rotatably fastens second member 24 to first member 22 .
[0023] Second member 24 includes a plurality of cam members 44 which are positioned on an inner wall of second member 24 . Cam members 44 are received in respective slots 36 of vanes 26 . Slots 36 of vanes 26 are configured such that rotation of second member 24 in relation to first member 22 effects movement of vanes 26 either into or out from throughbore 28 . Vanes 26 define an iris valve for selectively adjusting the diameter or cross-sectional area of throughbore 28 . Although throughbore 28 is illustrated as being circular, other non-circular configurations are envisioned, e.g., rectangular, square, oblong, etc.
[0024] In one embodiment, the outer periphery of second member 24 includes a series of gear teeth 50 . Actuator 18 also includes a series of gear teeth 52 . Gear teeth 52 are positioned to mesh with gear teeth 50 such that rotation of actuator 18 effects rotation of second member 24 in relation to first member 22 . Alternately, gear teeth 50 may only extend over a portion of the outer periphery of second member 24 . As discussed above, rotation of second member 24 in relation to first member 22 effects movement of vanes 26 to selectively vary the diameter or cross-sectional area of thoughbore 28 . It is envisioned that other types of actuators may be employed to operate valve assembly 14 .
[0025] Actuator 18 is rotatably mounted about a post 31 ( FIG. 3 ) formed on housing 12 and includes engagement structure 56 for engaging a valve assembly adjustment tool 57 . Engagement structure 56 may include a hexagonal recess. Alternately, other engagement structure including internal and external interlocking configurations may be used.
[0026] Referring again to FIGS. 2 and 3 , attachment mechanism 16 includes a drive member or ring 60 and a plurality of fastening elements or hoops 62 ( FIG. 3 ) which are spaced about ring 60 . Ring 60 is rotatably mounted on a circular rail 61 formed on housing 12 . Alternately, ring 60 can be rotatably secured to housing 12 using other known fastening techniques. It is envisioned that fastening elements 62 may comprise configurations other than hoops or, alternately, include a single element having one or more attachment surfaces. In one embodiment, ring 60 includes an inner gear surface 64 and an outer surface defining a helical thread 66 . Each hoop 62 includes a tip 62 a which may be pointed and a series of teeth or worm gear segments 62 b positioned to engage helical thread 66 of ring 60 .
[0027] Actuator 20 is rotatably mounted about a post 21 formed on an outer surface of housing 12 and includes gear teeth 68 which are positioned to mesh with gear surface 64 of drive ring 60 . When actuator 20 is rotated within housing 12 , drive ring 60 is also driven in rotation by engagement of gear teeth 68 with gear surface 64 . As drive ring 60 rotates, helical threads 66 engage teeth 62 b ( FIG. 3 ) of each of hoops 62 to advance tips 62 a of hoops 62 through openings 12 c of housing 12 along a substantially arcuate path. As will be discussed in further detail below, hoops 62 function to secure gastric restrictor assembly 10 within a body lumen. An attachment mechanism actuation tool 63 , which can be configured for transoral use, is provided to operate actuator 20 .
[0028] Referring to FIGS. 1 and 5 - 7 , during installation of gastric restrictor assembly 10 into a body lumen, e.g., the stomach 100 , gastric restrictor assembly 10 is positioned within stomach transorally. Alternately, gastric restrictor assembly 10 can be positioned with a body lumen during an open surgical procedure. The outer wall 90 of housing 12 is positioned adjacent an inner wall of stomach 100 . Next, actuator 20 ( FIG. 1 ) is operated to rotate drive ring 60 . As drive ring 60 is rotated within housing 12 , helical threads 66 , which engage teeth 62 b of hoops 62 , advances each of hoops 62 from within housing 12 along an arc-shaped path through a portion of inner wall 104 of stomach 100 . The arc-shaped path or curvature of hoops 62 should be such as to advance tips 62 a of hoops 62 through only a portion of inner wall 104 of stomach 100 without fully penetrating wall 104 of stomach 100 . This will prevent gastric fluids from exiting the stomach into the abdominal cavity. It is envisioned that the shape of hoops 62 may be changed to alter the path of travel of hoops 2 to effect full penetration of a wall of a body lumen if desired. Engagement of hoops 62 with wall 104 of stomach 100 secures gastric restrictor assembly 10 to inner wall 104 of stomach 100 . Although a multiplicity of hoops are illustrated in FIG. 1 , two or more hoops need only be provided to secure assembly 10 within the stomach.
[0029] When gastric restrictor assembly 10 is secured within the stomach, throughbore 28 of valve assembly 14 defines a passage through the stomach. The diameter of throughbore 28 can be selectively intraorally adjusted from a maximum diameter shown in FIG. 5 to a minimum diameter shown in FIG. 6 using valve assembly adjustment tool 57 . As discussed above, adjustment tool 57 ( FIG. 2 ) operates actuation member 18 to reposition vanes 26 of valve assembly 14 .
[0030] It will be understood that various modifications may be made to the embodiments disclosed herein. For example, the actuation mechanism for the valve assembly and/or the attachment mechanism not be gear driven but rather may include other types of drive mechanism, e.g., cam mechanism, etc. Further, the gastric restrictor assembly may be positioned at any position in the digestive tract where restriction may be warranted or desired. Therefore, the above description should not be construed as limiting, but merely as exemplifications of embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.
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A gastric restrictor assembly for positioning within the digestive tract, e.g., stomach, of a patient to treat obesity is disclosed. The gastric restrictor assembly includes an attachment mechanism for attaching the assembly within a body lumen and a valve assembly for adjusting the diameter of a throughbore defined by valve assembly. The gastric restrictor includes first and second actuators which can be actuated transorally for operating the attachment mechanism and the valve assembly.
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FIELD
[0001] The present teachings relate to refrigeration systems and, more particularly, to proofing an operating state of the refrigeration system.
BACKGROUND
[0002] Produced food travels from processing plants to retailers, where the food product remains on display case shelves for extended periods of time. In general, the display case shelves are part of a refrigeration system for storing the food product. In the interest of efficiency, retailers attempt to maximize the shelf-life of the stored food product while maintaining awareness of food product quality and safety issues.
[0003] The refrigeration system plays a key role in controlling the quality and safety of the food product. Thus, any breakdown in the refrigeration system or variation in performance of the refrigeration system can cause food quality and safety issues. Thus, it is important for the retailer to monitor and maintain the equipment of the refrigeration system to ensure its operation at expected levels.
[0004] Refrigeration systems generally require a significant amount of energy to operate. The energy requirements are thus a significant cost to food product retailers, especially when compounding the energy uses across multiple retail locations. As a result, it is in the best interest of food retailers to closely monitor the performance of the refrigeration systems to maximize their efficiency, thereby reducing operational costs.
[0005] Monitoring refrigeration system performance, maintenance and energy consumption are tedious and time-consuming operations and are undesirable for retailers to perform independently. Generally speaking, retailers lack the expertise to accurately analyze time and temperature data and relate that data to food product quality and safety, as well as the expertise to monitor the refrigeration system for performance, maintenance and efficiency. Further, a typical food retailer includes a plurality of retail locations spanning a large area. Monitoring each of the retail locations on an individual basis is inefficient and often results in redundancies.
SUMMARY
[0006] A method of proofing a refrigeration system operating state is provided. The method comprises monitoring a change in operating state of a refrigeration system component, determining an expected operating parameter of the refrigeration system component as a function of the change, and detecting an actual operating parameter of the refrigeration system component after the change. The method also comprises comparing the actual operating parameter to the expected operating parameter of the refrigeration component and detecting a malfunction of the refrigeration system component based on the comparison.
[0007] In other features, a controller executing the method is provided. In still other features, a computer-readable medium having computer-executable instructions for performing the method is provided.
[0008] Further areas of applicability of the present teachings will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the teachings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The present teachings will become more fully understood from the detailed description and the accompanying drawings, wherein:
[0010] FIG. 1 is a schematic illustration of an exemplary refrigeration system;
[0011] FIG. 2 is a schematic overview of a system for remotely monitoring and evaluating a remote location;
[0012] FIG. 3 is a simplified schematic illustration of circuit piping of the refrigeration system of FIG. 1 illustrating measurement sensors;
[0013] FIG. 4 is a simplified schematic illustration of loop piping of the refrigeration system of FIG. 1 illustrating measurement sensors;
[0014] FIG. 5 is a flowchart illustrating a signal conversion and validation algorithm according to the present teachings;
[0015] FIG. 6 is a block diagram illustrating configuration and output parameters for the signal conversion and validation algorithm of FIG. 5 ;
[0016] FIG. 7 is a flowchart illustrating a refrigerant properties from temperature (RPFT) algorithm;
[0017] FIG. 8 is a block diagram illustrating configuration and output parameters for the RPFT algorithm;
[0018] FIG. 9 is a flowchart illustrating a refrigerant properties from pressure (RPFP) algorithm;
[0019] FIG. 10 is a block diagram illustrating configuration and output parameters for the RPFP algorithm;
[0020] FIG. 11 is a graph illustrating pattern bands of the pattern recognition algorithm
[0021] FIG. 12 is a block diagram illustrating configuration and output parameters of a pattern analyzer;
[0022] FIG. 13 is a flowchart illustrating a pattern recognition algorithm;
[0023] FIG. 14 is a block diagram illustrating configuration and output parameters of a message algorithm;
[0024] FIG. 15 is a block diagram illustrating configuration and output parameters of a recurring notice/alarm algorithm;
[0025] FIG. 16 is a block diagram illustrating configuration and output parameters of a condenser performance monitor for a non-variable sped drive (non-VSD) condenser;
[0026] FIG. 17 is a flowchart illustrating a condenser performance algorithm for the non-VSD condenser;
[0027] FIG. 18 is a block diagram illustrating configuration and output parameters of a condenser performance monitor for a variable sped drive (VSD) condenser;
[0028] FIG. 19 is a flowchart illustrating a condenser performance algorithm for the VSD condenser;
[0029] FIG. 20 is a block diagram illustrating inputs and outputs of a condenser performance degradation algorithm;
[0030] FIG. 21 is a flowchart illustrating the condenser performance degradation algorithm;
[0031] FIG. 22 is a block diagram illustrating inputs and outputs of a compressor proofing algorithm;
[0032] FIG. 23 is a flowchart illustrating the compressor proofing algorithm;
[0033] FIG. 24 is a block diagram illustrating inputs and outputs of a compressor performance monitoring algorithm;
[0034] FIG. 25 is a flowchart illustrating the compressor performance monitoring algorithm;
[0035] FIG. 26 is a block diagram illustrating inputs and outputs of a compressor high discharge temperature monitoring algorithm;
[0036] FIG. 27 is a flowchart illustrating the compressor high discharge temperature monitoring algorithm;
[0037] FIG. 28 is a block diagram illustrating inputs and outputs of a return gas and flood-back monitoring algorithm;
[0038] FIG. 29 is a flowchart illustrating the return gas and flood-back monitoring algorithm;
[0039] FIG. 30 is a block diagram illustrating inputs and outputs of a contactor maintenance algorithm;
[0040] FIG. 31 is a flowchart illustrating the contactor maintenance algorithm;
[0041] FIG. 32 is a block diagram illustrating inputs and outputs of a contactor excessive cycling algorithm;
[0042] FIG. 33 is a flowchart illustrating the contactor excessive cycling algorithm;
[0043] FIG. 34 is a block diagram illustrating inputs and outputs of a contactor maintenance algorithm;
[0044] FIG. 35 is a flowchart illustrating the contactor maintenance algorithm;
[0045] FIG. 36 is a block diagram illustrating inputs and outputs of a refrigerant charge monitoring algorithm;
[0046] FIG. 37 is a flowchart illustrating the refrigerant charge monitoring algorithm;
[0047] FIG. 38 is a flowchart illustrating further details of the refrigerant charge monitoring algorithm;
[0048] FIG. 39 is a block diagram illustrating inputs and outputs of a suction and discharge pressure monitoring algorithm; and
[0049] FIG. 40 is a flowchart illustrating the suction and discharge pressure monitoring algorithm.
DETAILED DESCRIPTION
[0050] The following description is merely exemplary in nature and is in no way intended to limit the present teachings, applications, or uses. As used herein, computer-readable medium refers to any medium capable of storing data that may be received by a computer. Computer-readable medium may include, but is not limited to, a CD-ROM, a floppy disk, a magnetic tape, other magnetic medium capable of storing data, memory, RAM, ROM, PROM, EPROM, EEPROM, flash memory, punch cards, dip switches, or any other medium capable of storing data for a computer.
[0051] With reference to FIG. 1 , an exemplary refrigeration system 100 includes a plurality of refrigerated food storage cases 102 . The refrigeration system 100 includes a plurality of compressors 104 piped together with a common suction manifold 106 and a discharge header 108 all positioned within a compressor rack 110 . A discharge output 112 of each compressor 102 includes a respective temperature sensor 114 . An input 116 to the suction manifold 106 includes both a pressure sensor 118 and a temperature sensor 120 . Further, a discharge outlet 122 of the discharge header 108 includes an associated pressure sensor 124 . As described in further detail hereinbelow, the various sensors are implemented for evaluating maintenance requirements.
[0052] The compressor rack 110 compresses refrigerant vapor that is delivered to a condenser 126 where the refrigerant vapor is liquefied at high pressure. Condenser fans 127 are associated with the condenser 126 to enable improved heat transfer from the condenser 126 . The condenser 126 includes an associated ambient temperature sensor 128 and an outlet pressure sensor 130 . This high-pressure liquid refrigerant is delivered to the plurality of refrigeration cases 102 by way of piping 132 . Each refrigeration case 102 is arranged in separate circuits consisting of a plurality of refrigeration cases 102 that operate within a certain temperature range. FIG. 1 illustrates four (4) circuits labeled circuit A, circuit B, circuit C and circuit D. Each circuit is shown consisting of four (4) refrigeration cases 102 . However, those skilled in the art will recognize that any number of circuits, as well as any number of refrigeration cases 102 may be employed within a circuit. As indicated, each circuit will generally operate within a certain temperature range. For example, circuit A may be for frozen food, circuit B may be for dairy, circuit C may be for meat, etc.
[0053] Because the temperature requirement is different for each circuit, each circuit includes a pressure regulator 134 that acts to control the evaporator pressure and, hence, the temperature of the refrigerated space in the refrigeration cases 102 . The pressure regulators 134 can be electronically or mechanically controlled. Each refrigeration case 102 also includes its own evaporator 136 and its own expansion valve 138 that may be either a mechanical or an electronic valve for controlling the superheat of the refrigerant. In this regard, refrigerant is delivered by piping to the evaporator 136 in each refrigeration case 102 .
[0054] The refrigerant passes through the expansion valve 138 where a pressure drop causes the high pressure liquid refrigerant to achieve a lower pressure combination of liquid and vapor. As hot air from the refrigeration case 102 moves across the evaporator 136 , the low pressure liquid turns into gas. This low pressure gas is delivered to the pressure regulator 134 associated with that particular circuit. At the pressure regulator 134 , the pressure is dropped as the gas returns to the compressor rack 110 . At the compressor rack 110 , the low pressure gas is again compressed to a high pressure gas, which is delivered to the condenser 126 , which creates a high pressure liquid to supply to the expansion valve 138 and start the refrigeration cycle again.
[0055] A main refrigeration controller 140 is used and configured or programmed to control the operation of the refrigeration system 100 . The refrigeration controller 140 is preferably an Einstein Area Controller offered by CPC, Inc. of Atlanta, Ga., or any other type of programmable controller that may be programmed, as discussed herein. The refrigeration controller 140 controls the bank of compressors 104 in the compressor rack 110 , via an input/output module 142 . The input/output module 142 has relay switches to turn the compressors 104 on an off to provide the desired suction pressure.
[0056] A separate case controller (not shown), such as a CC-100 case controller, also offered by CPC, Inc. of Atlanta, Ga. may be used to control the superheat of the refrigerant to each refrigeration case 102 , via an electronic expansion valve in each refrigeration case 102 by way of a communication network or bus. Alternatively, a mechanical expansion valve may be used in place of the separate case controller. Should separate case controllers be utilized, the main refrigeration controller 140 may be used to configure each separate case controller, also via the communication bus. The communication bus may either be a RS-485 communication bus or a LonWorks Echelon bus that enables the main refrigeration controller 140 and the separate case controllers to receive information from each refrigeration case 102 .
[0057] Each refrigeration case 102 may have a temperature sensor 146 associated therewith, as shown for circuit B. The temperature sensor 146 can be electronically or wirelessly connected to the controller 140 or the expansion valve for the refrigeration case 102 . Each refrigeration case 102 in the circuit B may have a separate temperature sensor 146 to take average/min/max temperatures or a single temperature sensor 146 in one refrigeration case 102 within circuit B may be used to control each refrigeration case 102 in circuit B because all of the refrigeration cases 102 in a given circuit operate at substantially the same temperature range. These temperature inputs are preferably provided to the analog input board 142 , which returns the information to the main refrigeration controller 140 via the communication bus.
[0058] Additionally, further sensors are provided and correspond with each component of the refrigeration system and are in communication with the refrigeration controller 140 . Energy sensors 150 are associated with the compressors 104 and the condenser 126 of the refrigeration system 100 . The energy sensors 150 monitor energy consumption of their respective components and relay that information to the controller 140 .
[0059] Referring now to FIG. 2 , data acquisition and analytical algorithms may reside in one or more layers. The lowest layer is a device layer that includes hardware including, but not limited to, I/O boards that collect signals and may even process some signals. A system layer includes controllers such as the refrigeration controller 140 and case controllers 141 . The system layer processes algorithms that control the system components. A facility layer includes a site-based controller 161 that integrates and manages all of the sub-controllers. The site-based controller 161 is a master controller that manages communications to/from the facility.
[0060] The highest layer is an enterprise layer that manages information across all facilities and exists within a remote network or processing center 160 . It is anticipated that the remote processing center 160 can be either in the same location (e.g., food product retailer) as the refrigeration system 100 or can be a centralized processing center that monitors the refrigeration systems of several remote locations. The refrigeration controller 140 and case controllers 141 initially communicate with the site-based controller 161 via a serial connection, Ethemet, or other suitable network connection. The site-based controller 161 communicates with the processing center 160 via a modem, Ethernet, internet (i.e., TCP/IP) or other suitable network connection.
[0061] The processing center 160 collects data from the refrigeration controller 140 , the case controllers 141 and the various sensors associated with the refrigeration system 100 . For example, the processing center 160 collects information such as compressor, flow regulator and expansion valve set points from the refrigeration controller 140 . Data such as pressure and temperature values at various points along the refrigeration circuit are provided by the various sensors via the refrigeration controller 140 .
[0062] Referring now to FIGS. 3 and 4 , for each refrigeration circuit and loop of the refrigeration system 100 , several calculations are required to calculate superheat, saturation properties and other values used in the hereindescribed algorithms. These measurements include: ambient temperature (T a ), discharge pressure (P d ), condenser pressure (P c ), suction temperature (T s ), suction pressure (P s ), refrigeration level (RL), compressor discharge temperature (T d ), rack current load (I cmp ), condenser current load (I cnd ) and compressor run status. Other accessible controller parameters will be used as necessary. For example, a power sensor can monitor the power consumption of the compressor racks and the condenser. Besides the sensors described above, suction temperature sensors 115 monitor T s of the individual compressors 104 in a rack and a rack current sensor 150 monitors I cmp of a rack. The pressure sensor 124 monitors P d and a current sensor 127 monitors I cnd Multiple temperature sensors 129 monitor a return temperature (T c ) for each circuit.
[0063] The analytical algorithms include common and application algorithms that are preferably provided in the form of software modules. The application algorithms, supported by the common algorithms, predict maintenance requirements for the various components of the refrigeration system 100 and generate notifications that include notices, warnings and alarms. Notices are the lowest of the notifications and simply notify the service provider that something out of the ordinary is happening in the system. A notification does not yet warrant dispatch of a service technician to the facility. Warnings are an intermediate level of the notifications and inform the service provider that a problem is identified which is serious enough to be checked by a technician within a predetermined time period (e.g., 1 month). A warning does not indicate an emergency situation. An alarm is the highest of the notifications and warrants immediate attention by a service technician.
[0064] The common algorithms include signal conversion and validation, saturated refrigerant properties, pattern analyzer, watchdog message and recurring notice or alarm message. The application algorithms include condenser performance management (fan loss and dirty condenser), compressor proofing, compressor fault detection, return gas superheat monitoring, compressor contact monitoring, compressor run-time monitoring, refrigerant loss detection and suction/discharge pressure monitoring. Each is discussed in detail below. The algorithms can be processed locally using the refrigeration controller 140 or remotely at the remote processing center 160 .
[0065] Referring now to FIGS. 5 through 15 , the common algorithms will be described in detail. With particular reference to FIGS. 5 and 6 , the signal conversion and validation (SCV) algorithm processes measurement signals from the various sensors. The SCV algorithm determines the value of a particular signal and up to three different qualities including whether the signal is within a useful range, whether the signal changes over time and/or whether the actual input signal from the sensor is valid.
[0066] Referring now to FIG. 5 , in step 500 , the input registers read the measurement signal of a particular sensor. In step 502 , it is determined whether the input signal is within a range that is particular to the type of measurement. If the input signal is within range, the SCV algorithm continues in step 504 . If the input signal is not within the range an invalid data range flag is set in step 506 and the SCV algorithm continues in step 508 . In step 504 , it is determined whether there is a change (Δ) in the signal within a threshold time (t thresh ). If there is no change in the signal it is deemed static. In this case, a static data value flag is set in step 510 and the SCV algorithm continues in step 508 . If there is a change in the signal a valid data value flag is set in step 512 and the SCV algorithm continues in step 508 .
[0067] In step 508 , the signal is converted to provide finished data. More particularly, the signal is generally provided as a voltage. The voltage corresponds to a particular value (e.g., temperature, pressure, current, etc.). Generally, the signal is converted by multiplying the voltage value by a conversion constant (e.g., ° C./V, kPaV, A/V, etc.). In step 514 , the output registers pass the data value and validation flags and control ends.
[0068] Referring now to FIG. 6 , a block diagram schematically illustrates an SCV block 600 . A measured variable 602 is shown as the input signal. The input signal is provided by the instruments or sensors. Configuration parameters 604 are provided and include Lo and Hi range values, a time Δ, a signal Δ and an input type. The configuration parameters 604 are specific to each signal and each application. Output parameters 606 are output by the SCV block 600 and include the data value, bad signal flag, out of range flag and static value flag. In other words, the output parameters 606 are the finished data and data quality parameters associated with the measured variable.
[0069] Referring now to FIGS. 7 through 10 , refrigeration property algorithms will be described in detail. The refrigeration property algorithms provide the saturation pressure (P SAT ), density and enthalpy based on temperature. The refrigeration property algorithms further provide saturation temperature (T SAT ) based on pressure. Each algorithm incorporates thermal property curves for common refrigerant types including, but not limited to, R22, R 401 a (MP39), R 402 a (HP80), R 404 a (HP62), R 409 a and R 507 c.
[0070] With particular reference to FIG. 7 , a refrigerant properties from temperature (RPFT) algorithm is shown. In step 700 , the temperature and refrigerant type are input. In step 702 , it is determined whether the refrigerant is saturated liquid based on the temperature. If the refrigerant is in the saturated liquid state, the RPFT algorithm continues in step 704 . If the refrigerant is not in the saturated liquid state, the RPFT algorithm continues in step 706 . In step 704 , the RPFT algorithm selects the saturated liquid curve from the thermal property curves for the particular refrigerant type and continues in step 708 .
[0071] In step 706 , it is determined whether the refrigerant is in a saturated vapor state. If the refrigerant is in the saturated vapor state, the RPFT algorithm continues in step 710 . If the refrigerant is not in the saturated vapor state, the RPFT algorithm continues in step 712 . In step 712 , the data values are cleared, flags are set and the RPFT algorithm continues in step 714 . In step 710 , the RPFT algorithm selects the saturated vapor curve from the thermal property curves for the particular refrigerant type and continues in step 708 . In step 708 , data values for the refrigerant are determined. The data values include pressure, density and enthalpy. In step 714 , the RPFT algorithm outputs the data values and flags.
[0072] Referring now to FIG. 8 , a block diagram schematically illustrates an RPFT block 800 . A measured variable 802 is shown as the temperature. The temperature is provided by the instruments or sensors. Configuration parameters 804 are provided and include the particular refrigerant type. Output parameters 806 are output by the RPFT block 800 and include the pressure, enthalpy, density and data quality flag.
[0073] With particular reference to FIG. 9 a refrigerant properties from pressure (RPFP) algorithm is shown. In step 900 , the temperature and refrigerant type are input. In step 902 , it is determined whether the refrigerant is saturated liquid based on the pressure. If the refrigerant is in the saturated liquid state, the RPFP algorithm continues in step 904 . If the refrigerant is not in the saturated liquid state, the RPFP algorithm continues in step 906 . In step 904 , the RPFP algorithm selects the saturated liquid curve from the thermal property curves for the particular refrigerant type and continues in step 908 .
[0074] In step 906 , it is determined whether the refrigerant is in a saturated vapor state. If the refrigerant is in the saturated vapor state, the RPFP algorithm continues in step 910 . If the refrigerant is not in the saturated vapor state, the RPFP algorithm continues in step 912 . In step 912 , the data values are cleared, flags are set and the RPFP algorithm continues in step 914 . In step 910 , the RPFP algorithm selects the saturated vapor curve from the thermal property curves for the particular refrigerant type and continues in step 908 . In step 908 , the temperature of the refrigerant is determined. In step 914 , the RPFP algorithm outputs the temperature and flags.
[0075] Referring now to FIG. 10 , a block diagram schematically illustrates an RPFP block 1000 . A measured variable 1002 is shown as the pressure. The pressure is provided by the instruments or sensors. Configuration parameters 1004 are provided and include the particular refrigerant type. Output parameters 1006 are output by the RPFP block 1000 and include the temperature and data quality flag.
[0076] Referring now to FIGS. 11 through 13 , the data pattern recognition algorithm or pattern analyzer will be described in detail. The pattern analyzer monitors operating parameter inputs such as case temperature (T CASE ), product temperature (T PROD ), P s and P d and includes a data table (see FIG. 11 ) having multiple bands whose upper and lower limits are defined by configuration parameters. A particular input is measured at a configured frequency (e.g., every minute, hour, day, etc.). As the input value changes, the pattern analyzer determines within which band the value lies and increments a counter for that band. After the input has been monitored for a specified time period (e.g., a day, a week, a month, etc.) notifications are generated based on the band populations. The bands are defined by various boundaries including a high positive (PP) boundary, a positive (P) boundary, a zero (Z) boundary, a minus (M) boundary and a high minus (MM) boundary. The number of bands and the boundaries thereof are determined based on the particular refrigeration system operating parameter to be monitored. If the population of a particular band exceeds a notification limit, a corresponding notification is generated.
[0077] Referring now to FIG. 12 , a pattern analyzer block 1200 receives measured variables 1202 , configuration parameters 1204 and generates output parameters 1206 based thereon. The measured variables 1202 include an input (e.g., T CASE , T PROD , P s and P d ). The configuration parameters 1204 include a data sample timer and data pattern zone information. The data sample timer includes a duration, an interval and a frequency. The data pattern zone information defines the bands and which bands are to be enabled. For example, the data pattern zone information provides the boundary values (e.g., PP) band enablement (e.g., PPen), band value (e.g., PPband) and notification limit (e.g., PPpct).
[0078] Referring now to FIG. 13 , input registers are set for measurement and start trigger in step 1300 . In step 1302 , the algorithm determines whether the start trigger is present. If the start trigger is not present, the algorithm loops back to step 1300 . If the start trigger is present, the pattern table is defined in step 1304 based on the data pattern bands. In step 1306 , the pattern table is cleared. In step 1308 , the measurement is read and the measurement data is assigned to the pattern table in step 1310 .
[0079] In step 1312 , the algorithm determines whether the duration has expired. If the duration has not yet expired, the algorithm waits for the defined interval in step 1314 and loops back to step 1308 . If the duration has expired, the algorithm populates the output table in step 1316 . In step 1318 , the algorithm determines whether the results are normal. In other words, the algorithm determines whether the population of each band is below the notification limit for that band. If the results are normal, notifications are cleared in step 1320 and the algorithm ends. If the results are not normal, the algorithm determines whether to generate a notice, a warning, or an alarm in step 1322 . In step 1324 , the notification(s) is/are generated and the algorithm ends.
[0080] Referring now to FIG. 14 , a block diagram schematically illustrates the watchdog message algorithm, which includes a message generator 1400 , configuration parameters 1402 and output parameters 1404 . In accordance with the watchdog message algorithm, the site-based controller 161 periodically reports its health (i.e., operating condition) to the remainder of the network. The site-based controller generates a test message that is periodically broadcast. The time and frequency of the message is configured by setting the time of the first message and the number of times per day the test message is to be broadcast. Other components of the network (e.g., the refrigeration controller 140 , the processing center 160 and the case controllers) periodically receive the test message. If the test message is not received by one or more of the other network components, a controller communication fault is indicated.
[0081] Referring now to FIG. 15 , a block diagram schematically illustrates the recurring notification algorithm. The recurring notification algorithm monitors the state of signals generated by the various algorithms described herein. Some signals remain in the notification state for a protracted period of time until the corresponding issue is resolved. As a result, a notification message that is initially generated as the initial notification occurs may be overlooked later. The recurring notification algorithm generates the notification message at a configured frequency. The notification message is continuously regenerated until the alarm condition is resolved.
[0082] The recurring notification algorithm includes a notification message generator 1500 , configuration parameters 1502 , input parameters 1504 and output parameters 1506 . The configuration parameters 1502 include message frequency. The input 1504 includes a notification message and the output parameters 1506 include a regenerated notification message. The notification generator 1500 regenerates the input notification message at the indicated frequency. Once the notification condition is resolved, the input 1504 will indicate as such and regeneration of the notification message terminates.
[0083] Referring now to FIGS. 16 through 40 , the application algorithms will be described in detail. With particular reference to FIGS. 16 through 21 , condenser performance degrades due to gradual buildup of dirt and debris on the condenser coil and condenser fan failures. The condenser performance management includes a fan loss algorithm and a dirty condenser algorithm to detect either of these conditions.
[0084] Referring now to FIGS. 16 and 17 , the fan loss algorithm for a condenser fan without a variable speed drive (VSD) will be described. A block diagram illustrates a fan loss block 1600 that receives inputs of total condenser fan current (I CND ), a fan call status, a fan current for each condenser fan (I EACHFAN ) and a fan current measurement accuracy (δI FANCURRENT ). The fan call status is a flag that indicates whether a fan has been commanded to turn on. The fan current measurement accuracy is assumed to be approximately 10% of I EACHFAN if it is otherwise unavailable. The fan loss block 1600 processes the inputs and can generate a notification if the algorithm deems a fan is not functioning.
[0085] Referring to FIG. 17 , the condenser control requests that a fan come on in step 1700 . In step 1702 , the algorithm determines whether the incremental change in I CND is greater than or equal to the difference of I EACHFAN and δI FANCURRENT . If the incremental change is not greater than or equal to the difference, the algorithm generates a fan loss notification in step 1704 and the algorithm ends. If the incremental change is greater than or equal to the difference, the algorithm loops back to step 1700 .
[0086] Referring now to FIGS. 18 and 19 , the fan loss algorithm for a condenser fan with a VSD will be described. A block diagram illustrates a fan loss block 1800 that receives inputs of I CND , the number of fans ON (N), VSD speed (RPM) or output %, I EACHFAN and δI FANCURRENT . The VSD RPM or output % is provided by a motor control algorithm. The fan loss block 1600 processes the inputs and can generate a notification if the algorithm deems a fan is not functioning.
[0087] Referring to FIG. 19 , the condenser control calculates and expected current (I EXP )in step 1900 based on the following formula:
I EXP =N×I EACHFAN ×(RPM/100) 3
In step 1902 , the algorithm determines whether I CND is greater than or equal to the difference of I EXP and δI FANCURRENT . If the incremental change is not greater than or equal to the difference, the algorithm generates a fan loss notification in step 1904 and the algorithm ends. If the incremental change is greater than or equal to the difference, the algorithm loops back to step 1900 .
[0088] Referring specifically to FIGS. 20 and 21 , the dirty condenser algorithm will be explained in further detail. Condenser performance degrades due to dirt and debris. The dirty condenser algorithm calculates an overall condenser performance factor (U) for the condenser which corresponds to a thermal efficiency of the condenser. Hourly and daily averages are calculated and stored. A notification is generated based on a drop in the U averages. A condenser performance degradation block 2000 receives inputs including I CND , I CMP , P d , T a , refrigerant type and a reset flag. The condenser performance degradation block generates an hourly U average (U HRLYAVG ), a daily U average (U DAILYAVG ) and a reset flag time, based on the inputs. Whenever the condenser is cleaned, the field technician resets the algorithm and a benchmark U is created by averaging seven days of hourly data.
[0089] condenser performance degradation analysis block 2002 generates a notification based on U HRLYAVG , U DAILYAVG and the reset time flag. Referring now to FIG. 21 , the algorithm calculates T DSAT based on P d in step 2100 . In step 2102 , the algorithm calculates U based on the following equation:
U = I CMP ( I CND + Ionefan ) ( T DSAT - T a )
To avoid an error due to division by 0, a small nominal value I onefan is added to the denominator. In this way, even when the condenser is off, and I CND is 0, the equation does not return an error. I onefan corresponds to the normal current of one fan. The In step 2104 , the algorithm updates the hourly and daily averages provided that I CMP and I CND are both greater than 0, all sensors are functioning properly and the number of good data for sampling make up at least 20% of the total data sample. If these conditions are not met, the algorithm sets U=−1. The above calculation is based on condenser and compressor current. As can be appreciated, condenser and compressor power, as indicated by a power meter, or PID control signal data may also be used. PID control signal refers to a control signal that directs the component to operate at a percentage of its maximum capacity. A PID percentage value may be used in place of either the compressor or condenser current. As can be appreciated, any suitable indication of compressor or condenser power consumption may be used.
[0090] In step 2106 , the algorithm logs U HRLYAVG , U DAILYAVG and the reset time flag into memory. In step 2108 , the algorithm determine whether each of the averages have dropped by a threshold percentage (XX %) as compared to respective benchmarks. If the averages have not dropped by XX %, the algorithm loops back to step 2100 . If the averages have dropped by XX %, the algorithm generates a notification in step 2110 .
[0091] Referring now to FIGS. 22 and 23 , the compressor proofing algorithm monitors T d and the ON/OFF status of the compressor. When the compressor is turned ON, T d should rise by at least 20° F. A compressor proofing block 2200 receives T d and the ON/OFF status as inputs. The compressor proofing block 2200 processes the inputs and generates a notification if needed. In step 2300 , the algorithm determines whether T d has increased by at least 20° F. after the status has changed from OFF to ON. If T d has increased by at least 20° F., the algorithm loops back. If T d has not increased by at least 20° F., a notification is generated in step 2302 .
[0092] High compressor discharge temperatures result in lubricant breakdown, worn rings, and acid formation, all of which shorten the compressor lifespan. This condition can indicate a variety of problems including, but not limited to, damaged compressor valves, partial motor winding shorts, excess compressor wear, piston failure and high compression ratios. High compression ratios can be caused by either low suction pressure, high head pressure or a combination of the two. The higher the compression ratio, the higher the discharge temperature. This is due to heat of compression generated when the gasses are compressed through a greater pressure range.
[0093] High discharge temperatures (e.g., >300 F) cause oil break-down. Although high discharge temperatures typically occur in summer conditions (i.e., when the outdoor temperature is high and compressor has some problem), high discharge temperatures can occur in low ambient conditions, when compressor has some problem. Although the discharge temperature may not be high enough to cause oil break-down, it may still be higher than desired. Running compressor at relatively higher discharge temperatures indicates inefficient operation and the compressor may consume more energy then required. Similarly, lower then expected discharge temperatures may indicate flood-back.
[0094] The algorithms detect such temperature conditions by calculating isentropic efficiency (N CMP ) for the compressor. A lower efficiency indicates a compressor problem and an efficiency close to 100% indicates a flood-back condition.
[0095] Referring now to FIGS. 24 and 25 , the compressor fault detection algorithm will be discussed in detail. A compressor performance monitoring block 2400 receives P s , T s , P d , T d , compressor ON/OFF status and refrigerant type as inputs. The compressor performance monitoring block 2400 generates N CMP and a notification based on the inputs. A compressor performance analysis block selectively generates a notification based on a daily average of N CMP .
[0096] With particular reference to FIG. 25 , the algorithm calculates suction entropy (S SUC ) and suction enthalpy (h SUC ) based on T s and P s , intake enthalpy (h ID ) based on S SUC , and discharge enthalpy (h DIS ) based on T d and P d in step 2500 . In step 2502 , control calculates N CMP based on the following equation:
N CMP =( h ID −h SUC )/( h DIS −h SUC )*100
In step 2504 , the algorithm determines whether N CMP is less than a first threshold (THR 1 ) for a threshold time (t THRESH ) and whether N CMP is greater than a second threshold (THR 2 ) for t THRESH . If N CMP is not less than THR 1 for t THRESH and is not greater than THR 2 for t THRESH , the algorithm continues in step 2508 . If N CMP is less than THR 1 , for t THRESH and is greater than THR 2 for t THRESH , the algorithm issues a compressor performance effected notification in step 2506 and ends. The thresholds may be predetermined and based on ideal suction enthalpy, ideal intake enthalpy and/or ideal discharge enthalpy. Further, THR 1 may be 50%. An N CMP of less than 50% may indicate a refrigeration system malfunction. THR 2 may be 90%. An N CMP of more than 90% may indicate a flood back condition.
[0097] In step 2508 , the algorithm calculates a daily average of N CMP (N CMPDA ) provided that the compressor proof has not failed, all sensors are providing valid data and the number of good data samples are at least 20% of the total samples. If these conditions are not met, N CMPDA is set equal to −1. In step 2510 , the algorithm determines whether N CMPDA has changed by a threshold percent (PCT THR ) as compared to a benchmark. If N CMPDA has not changed by PCT THR , the algorithm loops back to step 2500 . If N CMPDA has not changed by PCT THR , the algorithm ends. If N CMPDA has changed by PCT THR , the algorithm initiates a compressor performance effected notification in step 2512 and the algorithm ends.
[0098] Referring now to FIGS. 26 and 27 , a high T d monitoring algorithm will be described in detail. The high T d monitoring algorithm generates notifications for discharge temperatures that can result in oil beak-down. In general, the algorithm monitors T d and determines whether the compressor is operating properly based thereon. T d reflects the latent heat absorbed in the evaporator, evaporator superheat, suction line heat gain, heat of compression, and compressor motor-generated heat. All of this heat is accumulated at the compressor discharge and must be removed. High compressor T d 's result in lubricant breakdown, worn rings, and acid formation, all of which shorten the compressor lifespan. This condition can indicate a variety of problems including, but not limited to damaged compressor valves, partial motor winding shorts, excess compressor wear, piston failure and high compression ratios. High compression ratios can be caused by either low P s , high head pressure, or a combination of the two. The higher the compression ratio, the higher the T d will be at the compressor. This is due to heat of compression generated when the gasses are compressed through a greater pressure range.
[0099] Referring now to FIG. 26 , a T d monitoring block 2600 receives T d and compressor ON/OFF status as inputs. The T d monitoring block 2600 processes the inputs and selectively generates an unacceptable T d notification. Referring now to FIG. 27 , the algorithm determines whether T d is greater than a threshold temperature (T THR ) for a threshold time (t THRESH ). If T d is not greater than T THR for t THRESH , the algorithm loops back. If T d is greater than T THR for t THRESH , the algorithm generates an unacceptable discharge temperature notification in step 2702 and the algorithm ends.
[0100] Referring now to FIGS. 28 and 29 , the return gas superheat monitoring algorithm will be described in further detail. Liquid flood-back is a condition that occurs while the compressor is running. Depending on the severity of this condition, liquid refrigerant will enter the compressor in sufficient quantities to cause a mechanical failure. More specifically, liquid refrigerant enters the compressor and dilutes the oil in either the cylinder bores or the crankcase, which supplies oil to the shaft bearing surfaces and connecting rods. Excessive flood back (or slugging) results in scoring the rods, pistons, or shafts.
[0101] This failure mode results from the heavy load induced on the compressor and the lack of lubrication caused by liquid refrigerant diluting the oil. As the liquid refrigerant drops to the bottom of the shell, it dilutes the oil, reducing its lubricating capability. This inadequate mixture is then picked up by the oil pump and supplied to the bearing surfaces for lubrication. Under these conditions, the connecting rods and crankshaft bearing surfaces will score, wear, and eventually seize up when the oil film is completely washed away by the liquid refrigerant. There will likely be copper plating, carbonized oil, and aluminum deposits on compressor components resulting from the extreme heat of friction.
[0102] Some common causes of refrigerant flood back include, but are not limited to inadequate evaporator superheat, refrigerant over-charge, reduced air flow over the evaporator coil and improper metering device (oversized). The return gas superheat monitoring algorithm is designed to generate a notification when liquid reaches the compressor. Additionally, the algorithm also watches the return gas temperature and superheat for the first sign of a flood back problem even if the liquid does not reach the compressor. Also, the return gas temperatures are monitored and a notification is generated upon a rise in gas temperature. Rise in gas temperature may indicate improper settings.
[0103] Referring now to FIG. 28 , a return gas and flood back monitoring block 2800 , receives T s , P s , rack run status and refrigerant type as inputs. The return gas and flood back monitoring block 2800 processes the inputs and generates a daily average superheat (SH), a daily average T s (T savg ) and selectively generates a flood back notification. Another return gas and flood back monitoring block 2802 selectively generates a system performance degraded notice based on SH and T savg .
[0104] Referring now to FIG. 29 , the algorithm calculates a saturated T s (T ssat ) based on P s in step 2900 . The algorithm also calculates SH as the difference between T s and T ssat in step 2900 . In step 2902 , the algorithm determines whether SH is less than a superheat threshold (SH THR ) for a threshold time (t THRSH ). If SH is not less than SH THR for t THRSH , the algorithm loops back to step 2900 . If SH is less than SH THR for t THRSH , the algorithm generates a flood back detected notification in step 2904 and the algorithm ends.
[0105] In step 2908 , the algorithm calculates an SH daily average (SH DA ) and T savg provided that the rack is running (i.e., at least one compressor in the rack is running, all sensors are generating valid data and the number of good data for averaging are at least 20% of the total data sample. If these conditions are not met, the algorithm sets SH DA =−100 and T savg =−100. In step 2910 , the algorithm determines whether SH DA or T savg change by a threshold percent (PCT THR ) as compared to respective benchmark values. If neither SH DA nor T savg change by PCT THR , the algorithm ends. If either SH DA or T savg changes by PCT THR , the algorithm generates a system performance effected algorithm in step 2912 and the algorithm ends.
[0106] The algorithm may also calculate a superheat rate of change over time. An increasing superheat may indicate an impending flood back condition. Likewise, a decreasing superheat may indicate an impending degraded performance condition. The algorithm compares the superheat rate of change to a rate threshold maximum and a rate threshold minimum, and determines whether the superheat is increases or decreasing at a rapid rate. In such case, a notification is generated.
[0107] Compressor contactor monitoring provides information including, but not limited to, contactor life (typically specified as number of cycles after which contactor needs to be replaced) and excessive cycling of compressor, which is detrimental to the compressor. The contactor sensing mechanism can be either internal (e.g., an input parameter to a controller which also accumulates the cycle count) or external (e.g., an external current sensor or auxiliary contact).
[0108] Referring now to FIG. 30 , the contactor maintenance algorithm selectively generates notifications based on how long it will take to reach the maximum count using a current cycling rate. For example, if the number of predicted days required to reach maximum count is between 45 and 90 days a notice is generated. If the number of predicted days is between 7 and 45 days a warning is generated and if the number of predicated days is less then 7, an alarm is generated. A contactor maintenance block 3000 receives the contactor ON/OFF status, a contactor reset flag and a maximum contactor cycle count (N MAX ) as inputs. The contactor maintenance block 3000 generates a notification based on the input.
[0109] Referring now to FIG. 31 , the algorithm determines whether the reset flag is set in step 3100 . If the reset flag is set, the algorithm continues in step 3102 . If the reset flag is not set, the algorithm continues in step 3104 . In step 3102 , the algorithm sets an accumulated counter (C ACC ) equal to zero. In step 3104 , the algorithm determines a daily count (C DAILY ) of the particular contactor, updates C ACC based on C DAILY and determines the number of predicted days until service (D PREDSERV ) based on the following equation:
D PREDSERV =( N MAX −C ACC )/ C DAILY
[0110] In step 3106 , the algorithm determines whether D PREDSERV is less than a first threshold number of days (D THR1 ) and is greater than or equal to a second threshold number of days (D THR2 ). If D PREDSERV is less than D THR1 and is greater than or equal to D THR2 , the algorithm loops back to step 3100 . If D PREDSERV is not less than D THR1 or is not greater than or equal to D THR2 , the algorithm continues in step 3108 . In step 3108 , the algorithm generates a notification that contactor service is required and ends.
[0111] An excessive contactor cycling algorithm watches for signs of excessive cycling. Excessive cycling of the compressor for an extended period of time reduces the life of compressor. The algorithm generates at least one notification a week to notify of excessive cycling. The algorithm makes use of point system to avoid nuisance alarm. FIG. 32 illustrates a contactor excessive cycling block 3200 , which receives contactor ON/OFF status as an input. The contactor excessive cycling block 3200 selectively generates a notification based on the input.
[0112] Referring now to FIG. 33 , the algorithm determines the number of cycling counts (N CYCLE ) each hour and assigns cycling points (N POINTS ) based thereon. For example, if N CYCLE /hour is between 6 and 12, N POINTS is equal to 1. if N CYCLE /hour is between 12 and 18, N POINTS is equal to 3 and if N CYCLE /hour is greater than 18, N POINTS is equal to 1. In step 3302 , the algorithm determines the accumulated N POINTS (N POINTSACC ) for a time period (e.g., 7 days). In step 3304 , the algorithm determines whether N POINTSACC is greater than a threshold number of points (P THR ). If N POINTSACC is not greater than P THR , the algorithm loops back to step 3300 . If N POINTSACC is greater than P THR , the algorithm issues a notification in step 3306 and ends.
[0113] The compressor run-time monitoring algorithm monitors the run-time of the compressor. After a threshold compressor run-time (t COMPTHR ), a routine maintenance such as oil change or the like is required. When the. run-time is close to t COMPTHR , a notification is generated. Referring now to FIG. 34 , a compressor maintenance block 3400 receives an accumulated compressor run-time (t COMPACC ), a reset flag and t COMPTHR as inputs. The compressor maintenance block 3400 selectively generates a notification based on the inputs.
[0114] Referring not to FIG. 35 , the algorithm determines whether the reset flag is set in step 3500 . If the reset flag is set, the algorithm continues in step 3502 . If the reset flag is not set, the algorithm continues in step 3504 . In step 3502 , the algorithm sets t COMPACC equal to zero. In step 3504 , the algorithm calculates the daily compressor run time (t COMPDAILY ) and predicts the number of days until service is required (t COMPSERV ) based on the following equation:
t COMPSERV =( t COMPTHR −t COMPACC )/ t COMPDAILY
[0115] In step 3506 , the algorithm determines whether t COMPSERV is less than a first threshold (D THR1 ) and greater than or equal to a second threshold (D THR2 ). If t COMPSERV is not less than D THR1 or is not greater than or equal to D THR2 , the algorithm loops back to step 3500 . If t COMPSERV is less than D THR1 and is greater than or equal to D THR2 , the algorithm issues a notification in step 3508 and ends.
[0116] Refrigerant level within the refrigeration system 100 is a function of refrigeration load, ambient temperatures, defrost status, heat reclaim status and refrigerant charge. A reservoir level indicator (not shown) reads accurately when the system is running and stable and it varies with the cooling load. When the system is turned off, refrigerant pools in the coldest parts of the system and the level indicator may provide a false reading. The refrigerant loss detection algorithm determines whether there is leakage in the refrigeration system 100 .
[0117] Refrigerant leak can occur as a slow leak or a fast leak. A fast leak is readily recognizable because the refrigerant level in the optional receiver will drop to zero in a very short period of time. However, a slow leak is difficult to quickly recognize. The refrigerant level in the receiver can widely vary throughout a given day. To extract meaningful information, hourly and daily refrigerant level averages (RL HRLYAVG , RL DAILYAVG ) are monitored. If the refrigerant is not present in the receiver should be present in the condenser. The volume of refrigerant in the condenser is proportional to the temperature difference between ambient air and condenser temperature. Refrigerant loss is detected by collectively monitoring these parameters.
[0118] Referring now to FIG. 36 , a first refrigerant charge monitoring block 3600 receives receiver refrigerant level (RL REC ), P d , T a , a rack run status, a reset flag and the refrigerant type as inputs. The first refrigerant charge monitoring block 3600 generates RL HRLYAVG , RL DAILYAVG , TD HRLYAVG , TD DAILYAVG , a reset date and selectively generates a notification based on the inputs. RL HRLYAVG , RL DAILYAVG , TD HRLYAVG , TD DAILYAVG and the reset date are inputs to a second refrigerant charge monitoring block 3602 , which selectively generates a notification based thereon. It is anticipated that the first monitoring block 3600 is resident within and processes the algorithm within the refrigerant controller 140 . The second monitoring block 3602 is resident within and processes the algorithm within the processing center 160 . The algorithm generates a refrigerant level model based on the monitoring of the refrigerant levels. The algorithm determines an expected refrigerant level based on the model, and compares the current refrigerant level to the expected refrigerant level.
[0119] Referring now to FIG. 37 , the refrigerant loss detection algorithm calculates T dsat based on P d and calculates TD as the difference between T dsat and T a in step 3700 . In step 3702 , the algorithm determines whether RL REC is less than a first threshold (RL THR1 ) for a first threshold time (t 1 ) or whether RL REC is greater than a second threshold (RL THR2 ) for a second threshold time (t 2 ). If RL REC is not less than RL THR1 for t 1 and RL REC is not greater than RL THR2 for t 2 , the algorithm loops back to step 3700 . If RL REC is less than RL THR1 for t 1 , or RL REC is greater than RL THR2 for t 2 , the algorithm issues a notification in step 3704 and ends.
[0120] In step 3706 , the algorithm calculates RL HRLYAVG and RL DAILYAVG provided that the rack is operating, all sensors are providing valid data and the number of good data points is at least 20% of the total sample of data points. If these conditions are not met, the algorithm sets TD equal to −100 and RL REC equal to −100. In step 3708 , RL REC , RL HRLYAVG , RL DAILYAVG , TD and the reset flag date (if a reset was initiated) are logged.
[0121] Referring now to FIG. 38 , the algorithm calculates expected daily RL values. The algorithm determines whether the reset flag has been set in step 3800 . If the reset flag has been set, the algorithm continues in step 3802 . If the reset flag has not been set, the algorithm continues in step 3804 . In step 3802 , the algorithm calculates TD HRLY and plots the function RL REC versus TD, according to the function RL REC =Mb×TD+Cb, where Mb is the slope of the line and Cb is the Y-intercept. In step 3804 , the algorithm calculates expected RL DAILYAVG based on the function. In step 3806 , the algorithm determines whether the expected RL DAILYAVG minus the actual RL DAILYAVG is greater than a threshold percentage. When the difference is not greater than the threshold percentage, the algorithm ends. When the difference is greater than the threshold, a notification is issued in step 3808 , and the algorithm ends.
[0122] P s and P d have significant implications on overall refrigeration system performance. For example, if P s is lowered by 1 PSI, the compressor power increases by about 2%. Additionally, any drift in P s and P d may indicate malfunctioning of sensors or some other system change such as set point change. The suction and discharge pressure monitoring algorithm calculates daily averages of these parameters and archives these values in the server. The algorithm initiates an alarm when there is a significant change in the averages. FIG. 39 illustrates a suction and discharge pressure monitoring block 3900 that receives P s , P d and a pack status as inputs. The suction and discharge pressure monitoring block 3900 selectively generates a notification based on the inputs.
[0123] Referring now to FIG. 40 , the suction and discharge pressure monitoring algorithm calculates daily averages of P s and P d (P sAVG and P dAvG , respectively) in step 4000 provided that the rack is operating, all sensors are generating valid data and the number of good data points is at least 20% of the total number of data points. If these conditions are not met, the algorithm sets P sAVG equal to −100 and P dAVG equal to −100. In step 4002 , the algorithm determines whether the absolute value of the difference between a current P sAVG and a previous P sAVG is greater than a suction pressure threshold (P sTHR ). If the absolute value of the difference between the current P sAVG and the previous P sAVG is greater than P sTHR , the algorithm issues a notification in step 4004 and ends. If the absolute value of the difference between the current P sAVG and the previous P sAVG is not greater than P sTHR , the algorithm continues in step 4006 .
[0124] In step 4006 , the algorithm determines whether the absolute value of the difference between a current P dAVG and a previous P dAVG is greater than a discharge pressure threshold (P dTHR ). If the absolute value of the difference between the current P dAVG and the previous P dAVG is greater than P dTHR , the algorithm issues a notification in step 4008 and ends. If the absolute value of the difference between the current P dAVG and the previous P dAVG is not greater than P dTHR , the algorithm ends. Alternatively, the algorithm may compare P dAVG and P sAVG to predetermined ideal discharge and suction pressures.
[0125] The description is merely exemplary in nature and, thus, variations are not to be regarded as a departure from the spirit and scope of the teachings.
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A method of proofing a refrigeration system operating state includes monitoring a change in operating state of a refrigeration system component, determining an expected operating parameter of the refrigeration system component as a function of the change, and detecting an actual operating parameter of the refrigeration system component after the change. The method also comprises comparing the actual operating parameter to the expected operating parameter of the refrigeration component and detecting a malfunction of the refrigeration system component based on the comparison. The method may be executed by a controller or stored in a computer-readable medium.
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This invention relates to valves for remotely indicating the relative positions of the valve and another object, e.g., a component in an underwater well assembly.
RELATED APPLICATIONS
Subject matter disclosed in this application is also disclosed and claimed in U.S. patent application Ser. Nos. 120,851 and 120,695, filed concurrently herewith by John E. Lawson, and 120,696, filed concurrently herewith by William A. Valka.
BACKGROUND OF THE INVENTION
Particularly in the art of drilling and completing underwater wells, and installing underwater equipment generally, it is frequently necessary to determine the relative positions of two devices. A typical example is the need for determining whether a multiple string tubing hanger installed in the bore of an underwater wellhead body occupies a desired rotational position relative to the wellhead. In the past, such needs have frequently been met by employing a television camera to view the devices and transmit the picture to, e.g., a vessel or other operational base at the surface of the body of water. In some cases, however, the position of the device to be checked is such that television viewing is difficult. In other cases, there is a need for a second remote indication, for redundancy. Prior-art workers have therefore employed position-sensitive valves to provide the remote indication as a change in fluid pressure, as seen for example in U.S. patent application Ser. No. 36,659, filed May 7, 1979, by Michael L. Wilson. Such valves must, however, pass a substantial fluid flow when open, serve when closed to provide a marked change in fluid pressure so as to avoid ambiguity, and be operated by straight line relative movement between the valve and another object, and there has been a continuing need for improvement to satisfy these requirements.
OBJECTS OF THE INVENTION
A general object is to devise a valve of the type described which will satisfactorily handle fluid flow of substantial volume when open, yet close with a positive action in response to relative movement between the valve and another object.
A further object is to provide such a valve which is highly dependable and free from ambiguity in its position-indicating function.
Another object is to provide such a valve which does not require that the valve be brought to an unduly precise position in order to respond to the presence of another object in order to achieve actuation.
SUMMARY OF THE INVENTION
Valves according to the invention comprise a valve body having a longitudinal axis and defining an internal chamber, a cylinder and a guide bore, the chamber being located between the cylinder and the guide bore, the cylinder and bore being coaxial, and the bore opening through one end of the body. A valve seat member is slidably disposed in the guide bore and presents an outwardly facing valve seat, there being means on the valve seat member to engage a stop shoulder on the valve body so that outward movement of the valve seat member relative to the body is limited. The valve seat member has a transverse partition with a central through bore and a plurality of flow passages. A movable valve member is employed which comprises a head and a spindle, the head having a surface shaped and dimensioned to coact with the seat to close the valve against fluid flow through the valve seat members, the spindle projecting from the head through the through bore of the valve seat member, through the internal chamber and into the cylinder. A piston is operatively disposed in the cylinder and secured to the end of the spindle opposite the head. Between the cylinder and the internal chamber, the valve body has a transverse annular shoulder facing the piston to limit downward movement of the piston and movable valve member. Spring means is provided to bias the combination of the movable valve member, with the piston attached thereto, and the valve seat member in a direction such that the valve seat member and piston engage their respective shoulders. An inlet port is provided for supply of pressure fluid to the internal chamber. A seal ring is carried by the piston to seal with the wall of the cylinder, and the valve seat member is also equipped with a seal ring to seal with the wall of the guide bore. The diameter of the valve seat member at its seal ring is slightly but significantly less than the diameter of the piston at its seal ring so that, when the valve is closed, the pressure in the internal chamber acts on an effective piston area which is larger than the effective area of the valve seat member acted on by the same pressure.
In operation, relative movement between the valve body and an object adjacent the head, with the movement being such as to cause the movable head to engage the seat, causes initial closing of the valve against line pressure. Since fluid can no longer escape, and full line pressure remains applied via the inlet port to the internal chamber, the greater effective area of the piston as compared to that of the valve seat member causes the piston to continue its movement and, the piston being rigidly connected to the head of the movable valve member, causes the head to force the valve seat member further inwardly against the biasing force of the spring means. This action not only increases the pressure between the head and valve seat, but also eliminates the need for a precise relationship between the head and the object it is to engage, since the valve head in effect retreats away from the object once the valve has closed. Such retreat of the movable valve member away from the object which was engaged with the head to cause the initial movement also has the advantage of leaving the object in a clearly observable position spaced from the head.
IDENTIFICATION OF THE DRAWINGS
In order that the manner in which the foregoing and other objects are achieved according to the invention can be understood in detail, one particularly advantageous embodiment thereof will be described with reference to the accompanying drawings, which form part of the original disclosure of this application, and wherein:
FIGS. 1 and 2 are top plan and side elevational views, respectively, of a tool embodying a valve according to the invention;
FIG. 3 is a view partly in vertical cross section and partly in side elevation taken generally on line 3--3, FIG. 1, and showing the tool landed on an underwater well assembly and engaged with a multiple string tubing hanger forming part of that assembly; and
FIG. 4 is a vertical cross-sectional view of a valve unit according to the invention and forming part of the tool of FIGS. 1-3.
DETAILED DESCRIPTION OF THE INVENTION
The embodiment of the invention illustrated comprises a support 1 comprising an upper member 2, a lower member 3 and two guide arms 4 and 4a. Upper member 2 comprises an upstanding cylindrical hub 5 and, at the bottom of the hub, a flat transverse flange 6 secured rigidly to the hub. The upper end of the hub has a threaded socket 7, to be connected to a handling string (not shown), the socket opening downwardly into a blind bore 8 which communicates on the one hand with a radial outlet bore 9 and, on the other hand, with the interior of the handling string pipe when the hub is connected to the handling string. Lower member 3 is in the form of a flat plate of circular plan shape.
Guide arms 4 and 4a form part of a guide frame indicated generally at 10 and comprising four side members 11 arranged to define a square, a guide tube 12 being secured at each corner of the square and the guide arms 4, 4a extending along the respective diagonals of the square. Arm 4 extends continuously from corner to corner of the frame, while arm 4a is in two halves, one extending from one corner of the square to the center of arm 4, the other extending from the opposite corner to the center of arm 4. All joints between arms 4, 4a, side members 11 and guide tubes 12 are welded to provide the rigid frame. Arms 4, 4a are of I-beam configuration. Flange 6 of upper member 2 is made up of four triangular pieces welded to the upper flanges of arms 4, 4a at the center of the frame, and lower member 3 is welded to the lower flanges of arms 4, 4a at the center of the frame. Thus, the guide arms effectively extend through the space between flange 6 and member 2.
A locator member 15, comprising a flat circular plate 16 of the same size as lower member 3 and two locator splines 17 and 17a depending from and secured rigidly to plate 16, is employed in conjunction with a locator sleeve or skirt 18 having at its upper end a transverse annular outwardly and inwardly projecting flange 19, the inner diameter of flange 19 being such that the flange snugly embraces splines 17, 17a. Bolts, as at 20, extend through aligned holes in flange 19, plate 16 and member 3, as shown, to secure those members rigidly together with locator member 15 centered on the central axis of hub 5. Splines 17, 17a are of arcuate transverse cross section and are dimensioned to extend downwardly through the respective ones of two gaps of a flange 21 at the upper end of the body of a multiple string tubing hanger 22 supported in the bore of a wellhead lower body 23, the tubing hanger being described in detail in copending application Ser. No. 120,695 filed concurrently herewith by John E. Lawson. As fully explained in that application, the two flange gaps are opposed across the hanger body and are of different arcuate width. Accordingly, spline 17 is made with a width such as to be snugly accommodated by one of the gaps, and flange 17a has a width such as to be snugly accommodated by the other gap. Hence, splines 17, 17a cannot be inserted through the gapped flange 21 of hanger 22 except when locator member 15 is so aligned and oriented relative to the tubing hanger that each spline 17, 17a is centered on its respective gap. Sleeve 18 of member 15 has a right cylindrical inner surface dimensioned to slidably embrace the upper end portion of wellhead lower body 23.
In locations spaced outwardly from hub 5 and adjacent to the web of one of the guide arms, four sets of vertically aligned openings are provided in flange 19, plate 16, member 3 and flange 6, as seen in FIG. 3. Each such set of openings accommodates a feeler rod, all four feeler rods being identical and one being shown in detail at 24, FIG. 3. At its lower end, the rod has a flat head 25 disposed for flush engagement with the upper end face of wellhead body member 23. Save for its upper tip, which has a threaded portion of smaller diameter, rod 24 is of constant diameter throughout its length and is slidably engaged by the walls of the opening in flange 6 and by an opening in the top wall of a cup-shaped spring retainer 26 carried by member 3, so the rod is retained in an upright position but free to move upwardly or downwardly. The upper end of rod 24 carries a washer 27 secured between a nut 28 and the shoulder (not shown) at the lower end of the smaller diameter threaded tip portion. A compression spring 29 is housed in retainer 26 and engaged between the top wall of the retainer and head 25, so as to bias rod 24 downwardly. The length of the rod between head 25 and washer 27 is predetermined and is significantly greater than the space between the lower end of retainer 26 and the upper surface of flange 6. As will be clear by comparing FIGS. 1 and 3, all of the feeler rods 24 are aligned above the annular space between the inner surface of skirt 18 and a cylindrical surface containing the arcuate outer faces of splines 17, 17a.
Hub 5 and respective guide arms 4, 4a are interconnected by four triangular brace plates 30 each centered on one of guide arms 4, 4a. A shroud is provided for the rod 24 shown in detail in FIG. 3 and comprises a flat background plate 31 and two flat side plates 32, 33 rigidly secured to flange 6 and extending upwardly therefrom. Background plate 31 has its ends welded to two of the brace plates 30 while side plates 32, 33 project outwardly from the background plate and at right angles thereto to define a window through which the background plate can be viewed. Background plates 34-36 are provided, similarly to plate 31, in each of the remaining spaces between adjacent pairs of brace plates 30, as will be clear from FIG. 1. The outwardly exposed face of each background plate 31 and 34-36 is provided with a visible reference line, as at 37, FIG. 3, all of the reference lines lying in a common plane parallel to flange 6 and spaced thereabove by a distance equal to the space between indicator washer 27 and the upper face of flange 6 when the tool is seated on the wellhead assembly with rod heads 25 engaging the upper end of body 23. Thus, when tubing hanger 22 is properly landed and oriented, and when rods 24 are in their raised indicating positions, a television camera 38 will observe washer 27 aligned with reference line 37 on plate 31, the principal axis of the lens being directed to line 37 through the position occupied by washer 27 when the feeler rod is in its indicating position.
Secured to the upper edges of shroud walls 31-33 is a mounting bar 40 having a threaded through bore aligned coaxially with feeler rod 24. An indicator valve unit, indicated generally at 41 in FIG. 3 and shown in detail in FIG. 4, is secured in the through bore of mounting bar 40, as by external threads 42 on lower member 43 of an upright valve body 44. Body 44 is completed by an upper body member 59 and defines a cylindrical internal chamber 45, a cylinder 46 of larger diameter than chamber 45 and located thereabove, and a guide bore 47 located below chamber 45 and of smaller diameter. Chamber 45, cylinder 46 and bore 47 are coaxial. A valve seat member 48 has its right cylindrical outer surface 49 slidably embraced by the wall of bore 47. Member 48 is tubular for most of its length, so as to define an outlet passage 50 terminating in an upwardly and inwardly tapering transverse annular valve seat 51. The upper end of member 48 is outwardly enlarged to provide an outer flange 52 capable of downward engagement with a shoulder 53 provided by body member 43. Also at its upper end, member 48 has a partition 54 with through passages 55 for fluid flow and a central through bore 56. A compression spring 57 is engaged between the upper end of member 48 and a downwardly facing transverse annular shoulder 58 in upper body member 59.
A movable valve member 60 has an elongated spindle 61 and a head portion 62 presenting an upwardly directed frustoconical face 63 dimensioned to mate with valve seat 51. Spindle 61 extends upwardly through bore 56, being slidable with respect thereto, and completely through chamber 45 to terminate in a threaded upper tip engaged in a threaded blind bore in piston 64. Piston 64 has a diameter such as to be slidably embraced by the wall of cylinder 46. Cylinder 46 opens upwardly and is closed by end wall member 66, as shown, a compression spring 65 being engaged between member 66 and an upwardly directed shoulder 67 on the piston. A radial inlet bore 68 extends through the side wall of chamber 45 and is threaded to accept a connector at one end of an external conduit 69, FIG. 1, the other end of conduit 69 being connected to bore 9 of hub 5, placing internal chamber 45 of the valve unit in communication with bore 8 of hub 5 and thus, via the bore of the handling string, with a source of fluid under pressure on the operational base at the surface of the body of water. An outlet or vent 70 is provided for cylinder 46, as shown.
Body members 43, 59 are generally tubular and secured rigidly together, as by a threaded joint between a dependent portion 59a of member 59 and the upper end portion of member 43, as shown. A fluid-tight seal is provided, as by an O-ring, between portion 59a and member 43. Sliding fluid-tight seals are provided between valve seat member 48 and surface 47 of member 43, and between piston 64 and the surrounding cylinder wall, as shown. The guide bore 47 has a diameter significantly smaller than that of the wall of cylinder 46 so that, when the valve is closed, with line pressure still applied via inlet 68 to chamber 45, the pressure in chamber 45 acts against a larger effective area of the piston and a smaller effective area of the valve seat member and the combination of the piston, movable valve member and valve seat member is therefore moved upwardly, as a result of the difference in effective areas, until the valve seat member engages the lower end of body portion 59a.
Valve member 60 is normally in its lower, open position as seen in FIG. 4 so that pressure fluid supplied to chamber 45 at a constant pressure escapes via passages 55 and outlet 50. The greater effective area of piston 64 is not adequate, in view of the strength of springs 57 and 65, to provide a fluid pressure-generated force adequate to move valve member 60 upwardly. Hence, the valve remains open and fluid pressure observed by a gauge (not shown) at the source on the operational base remains steady. When rod 24 is forced upwardly to its indicating position, as a result of engagement with body 23, valve member 60 is moved upwardly to engage surface 63 with seat 51 and force valve seat member 48 slightly upwardly in guide bore 47. With the valve thus closed, and pressure fluid still supplied to chamber 45, the greater effective area of piston 64, as compared to that of a valve seat member 48, provides net force acting on the piston in excess of the spring force, so that the piston, movable valve member and valve seat member move upwardly until the valve seat member engages body portion 59a as a stop. Since fluid can no longer escape and the movable elements are stopped, an abrupt increase in pressure is observed at the operational base, signalling that the tubing hanger is properly landed in its oriented position.
It will be understood that seat 51 and surface 63 are machined to coact in metal-to-metal seal fashion, so that the mechanical action resulting from engagement of valve head 62 with feeler rod 24 is adequate for closing the valve. The increased pressure between surface 63 and seat 51 which results from continued upward movement of the piston, movable valve member and valve seat member against the biasing force of the springs adds to positiveness of closing of the valve but has the greater advantage that, since valve head 62 retreats upwardly from feeler rod 24 after the valve has been closed, there is no need for the high degree of dimensional accuracy which would be required if, once the valve closed, head 62 rigidly opposed the feeler rod.
From FIG. 4, it will be seen that, when the valve is closed, head 62 of the movable valve member is located wholly outside of the valve body. Once the valve has been actuated to close, as a result of engagement of head 62 with the upper end of feeler rod 24, the action of the valve causes head 62 of movable valve member 60 to move upwardly, away from the end of rod 24, so that indicator washer 27 is more clearly distinguishable against background plate 31.
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Indicator valve unit for providing a change in fluid pressure as a remote indication of whether an object occupies a desired position. Particularly useful for indicating whether a component, such as a multiple string tubing hanger, has been properly oriented and landed in an underwater well installation, the indicator valve unit provides for automatic separation of the sensing element of the unit from the sensed object as soon as the valve has been actuated.
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This application is a continuation-in-part of application Ser. No. 366,358 filed Jun. 15, 1989, now abandoned; which is a continuation of application Ser. No. 237,526 filed Aug. 26, 1988, now abandoned.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention generally relates to power-driven conveyors and to conveyors having a means to facilitate cleaning the conveyor or sterilizing means.
2. Description of the Prior Art
It is necessary to clean and sterilize the conveyor belt in the food processing industry as well as in other situations. A number of scrapers and wipers have been developed to do this job. It is desired to accomplish the best possible cleaning job, which often is judged by a bacteria count taken from the cleaned belt. Also, it is desired to accomplish the job by the easiest, least costly method.
A number of patents have disclosed methods and apparatus for cleaning conveyor belts. One is West German Patent No. 2,950,346, which shows a conveyor belt cleaner that includes a reservoir trough from which a cleaner belt picks up cleaning fluid and transfers it to the belt to be cleaned. The cleaner belt is moving in the opposite direction to the conveyor belt and simultaneously applies cleaning fluid and scours the conveyor belt. The cleaner belt is power-driven and appears to operate against the conveyor belt on a full time basis.
West German Patent No. 2,505,874 shows a cleaner for escalator handrails. The cleaning liquid is transferred to the handrail by application rollers, at least one of which rotates in a direction opposite to the handrail. Alternatively, an endless sponge or brush band applies the fluid while rotating oppositely to the handrail.
U.S. Pat. No. 3,946,853 to Ishida discloses a solution-bearing pad that is resiliently biased into contact with a moving belt in order to clean, polish, or disinfect an escalator handrail. The pad is secured by a C-shaped housing that is engaged over the sides of the handrail, and, apparently, the housing eventually rests against some fixed portion of the escalator so that the belt slides through the pad.
U.S. Pat. No. 3,941,241 to Hishitani discloses a similar escalator cleaning pad and housing, except that this housing is firmly connected to a fixed part of the escalator by a fastener.
Russian Patent No. 914,432 discloses a conveyor belt cleaning system in which an endless tape is sprayed with solvent and then moves against the dirty side of the belt as both belt and tape ride over a tape drum. Subsequently, the tape travels through a water tank and is pressed against a drying roller.
U.S. Pat. No. 1,543,411 to Wittig discloses a belt cleaner having a spray header that wets the belt. At a downstream location a rotating brush cleans the belt, while further downstream the knife scrapes the belt.
U.S. Pat. No. 4,344,361 to MacPhee et al. discloses a cleaner for a blanket cylinder. The cleaner advances a cloth sheet between a supply roll and a take-up roll. Between the two rolls, water and solvent are supplied to the cloth, and an inflatable bladder presses the cloth against the cylinder for cleaning.
Although these types of belt cleaners are known, it would be desirable to have a belt cleaner that need not be permanently installed on the belt, but rather could be applied when necessary and then removed to another area so that the belt cleaner could be cleaned and prepared for the next use.
Also, it would be desirable to have a suitable structure to enable the belt cleaner to be applied to substantially any conveyor belt without specially adapting the conveyor to receive the cleaner.
Another desirable feature is to have a belt cleaner that carries its own supply of cleaning solution so that the cleaner is not dependent upon the absorbency of the pad to handle the cleaning requirements of the entire belt.
Still another desirable feature is to have a belt cleaner that can quickly and inexpensively be cycled for repeated use.
To achieve the foregoing and other objects and in accordance with the purpose of the present invention, as embodied and broadly described herein, the conveyor belt cleaning apparatus and method of this invention may comprise the following.
SUMMARY OF THE INVENTION
Against the described background, it is therefore a general object of the invention to provide an improved conveyor belt cleaner that is self-retained in the desired location for performing its cleaning function.
Another object is to provide a belt cleaner that is capable of carrying its own cleaning solution and automatically supplying this solution.
An important object is to provide a belt cleaner that has high cleaning capacity so that it can rapidly clean conveyor belts even in food processing plants, where cleaning requirements are severe.
A further object to to provide a belt cleaning apparatus that replaces the need for hand scrubbing of belts in food processing plants and accomplishes the cleaning functions in an even manner over the food contact surface of the belt.
Additional objects, advantages and novel features of the invention shall be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by the practice of the invention. The object and the advantages of the invention may be realized and attained by means of the instrumentalities and in combinations particularly pointed out in the appended claims.
According to the invention, a conveyor belt cleaning apparatus provides a tank having a bottom surface with a substantially flat, planar portion joined near its forward end to a downwardly curved portion. A fluid absorbent pad carried by the tank over the tank's bottom surface. Orifices apply fluid from the tank to the pad.
According to another aspect of the invention, a conveyor belt cleaning apparatus provides a tank having a bottom surface with a generally planar, pressure-applying surface portion for, in use, overlying a substantially straight run of conveyor belt and a depending hooking surface for, in use, engaging a reverse bending portion of a conveyor belt. A fluid dispensing device discharges fluid from within the tank to the proximity of the bottom surface of the tank. A pad fastening means attaches a wiping pad across the bottom surface of the tank.
The accompanying drawings, which are incorporated in and form a part of the specification illustrate preferred embodiments of the present invention, and together with the description, serve to explain the principles of the invention. In the drawings:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view of the belt cleaner, with portions of the pad fastener shown in phantom.
FIG. 2 is a top plan view of the belt cleaner, with the fluid dispensing nozzles on the bottom of the apparatus shown in phantom.
FIG. 3 is side elevational view of the belt cleaner as applied to a conveyor belt and with optional cleaner units in tandem.
FIG. 4 is a top plan view of the junction between two tandem cleaner units, showing the joining means.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference to the embodiment of the invention shown in FIGS. 1 and 2, the conveyor belt cleaning apparatus 10 is a free standing tank 12 or similar container capable of holding a liquid. The lower surface 14 of tank 12 is configured in at least two portions in longitudinal alignment. The first is a substantially flat, planar, pressure applying surface 16, and the second is a depending, downwardly curved, hooking surface 18 located near the forward end of the first surface portion. In addition, the tank is supplied with a means for discharging or feeding fluid from within the tank to the proximity of its bottom surface. A nozzle 20 or other fluid passage orifice is suitable for this purpose. Finally, the tank carries a fluid absorbent pad 22 over the bottom surface, where the fluid discharge means may apply fluid to the pad.
The tank 12 is a fluid carrying chamber and may be either open or closed, although a closed tank is preferred from the standpoint of ease of use. Thus, the tank may have a top wall 24, a pair of right and left side walls 26, a rear wall 28, a front wall 30, and a bottom wall 32. Together, these walls define an enclosed interior chamber that may hold a suitable cleaning solution for application to a conveyor belt.
The cleaning solution typically is a liquid and may be a wetting agent, water, bleach solution, or combinations of these elements. Many cleaning solutions are known for the purpose of cleaning conveyor belts, and the exact solution used is a matter to be coordinated with the cleaning requirements of the environment of each conveyor belt. It may be noted that the tank may be formed of a chemically impervious material such as rubber, plastic or other synthetic, so that the selected cleaning material is harmless to the tank. In addition, the fluid discharge orifices may be sized to accommodate the chosen fluid.
The tank has an interior volume defined by the various enclosing walls. It is desired that the tank have considerable mass so that it will be capable of remaining stationary above a moving conveyor belt merely by the hooked relationship of the bottom surface portion 18 over the end reverse curve of the belt. Thus, the walls may have considerable thickness and, if desired, may be formed of dense materials or may contain ballast of denser materials. For example, it has been found desirable for a tank having about sixteen inch width and twenty-four inch length to have a minimum weight of fifteen pounds. Of course, another technique for achieving this weight is to operate the cleaner with sufficient residual liquid in a tank of any empty weight.
The weight and balance of the tank are designed to aid its free-standing nature. The tank is provided with a filler cap 34 of the self-venting variety, which are well known commodities. As shown in FIGS. 1 and 2, this cap is preferred to be located near the front wall 30, at a position similar to the illustrated longitudinal position of the orifices 20. In addition, one or more handles 36 may be attached to the tank for ease of handling. At least one handle 36 is preferred to be located on the front wall 30 so that the tank can be carried with the front wall in top position. This orientation allows the fluid in the tank to be pooled in the rearward area of the tank and, correspondingly, to avoid leakage at the cap 34 or orifices 20. Additional handles or inset hand grip areas may be supplied as desired in the side and end walls. The front wall 30 may have considerable thickness, extending rearwardly almost to the filler cap and orifices in order to locate a permanent mass over the downward curve 18 of the lower surface of wall 32.
Lower surface 14 of wall 32 is the working surface of the tank. Rearward portion 16 typically is longitudinally planar or generally so, in order to provide a broad, pressure applying area that will overlie a flat run of conveyor belt. This surface may have texture or raised pattern as may be desired to assure or assist uniformity of contact as portion 16 presses the pad 22 against the belt. Special configurations such as longitudinal grooves, ribs, curves, or troughs may be molded into this section of the surface 14 as desired to conform to the configuration of a specific belt.
The forward portion 18 of lower surface 14 depends from the longitudinal plane of surface portion 16. This depending surface portion 18 is preferred to be a curve, although other configurations such as a straight wall may be employed. Portion 18 constitutes a hook or like anchoring means that is placed over the end of the conveyor belt, a the rear reverse bend. Thus, the typical conveyor belt will rise through this reverse bend and move under wall 32 from the front surface portion 18 toward the rear surface portion 16. It is primarily portion 18 that secures the tank against moving with the belt. If the curve 18 ends at a distance from front wall 30, the lower surface may include an additional bottom wall surface 38 connecting the lower end of the curve to wall 30.
The fluid dispensing orifices or nozzles 20 are formed or mounted in bottom wall 32. In the simplist embodiment, it has been found that six orifices of 0.045 inch diameter, spaced in lateral alignment about 21/2 inches apart, are well suited for use with a tank having a width of sixteen and one-half inches. In other embodiments, the nozzles 20 may be of the screw-in type to permit a choice of orifice size. Adjustable orifices allow the flow rate of the solution in the tank to the pad 22. Flow may be adjusted to accommodate different belt speed, belt length, or specific cleaning situations, such as if it is desired to saturate the conveyor belt. The orifices are gravity fed and feed the cleaning solution directly from the tank to the general proximity of the bottom surface of wall 32. When pad 22 is in place and the tank is in operation on a conveyor belt, the solution is delivered onto the pad. Thus, the number, size and position of the orifices will control fluid feed to the pad. The orifices are preferred to be near the forward end of surface portion 16 so that they set the pad 22 near the upstream end of the pad. Although other feed systems might be used, gravity feed is preferred for its simplicity and its contribution to the free-standing nature of the tank.
The pad 22 is a fluid absorbent cloth or similar wipe. It is preferred to be mounted to the tank 12 between the front wall 30 and rear wall 28, with sufficient slack to permit the pad to conform to the configuration of the bottom surface 14. The width of the pad should be substantially as great as bottom surface 14. The mounting between the pad and the tank is preferred to be of a removeable type. Thus, one type of mounting could be by adhesive, while another could be by reuseable fasteners, such as snaps, buttons, Velcro, or friction fasteners. The preferred wipe or pad is disposable.
A preferred pad fastening means is shown in FIGS. 1 and 2 to be a wedge lock friction fastener 40. One such fastener may be mounted at each of the front and rear walls of the tank. This fastener may include a bracket 42 attached to the side walls of the tank and extending across and spaced longitudinally from the respective front and rear walls. Held between the bracket and its respective front or rear tank wall is a laterally extending wedge shaped fastening bar 44. A pad may be installed and locked in such a fastener by being inserted between the bar 44 and the abutting end wall of the tank. Thereafter, the bar is depressed into the bracket to frictionally lock the pad in place. Pulling forces exerted from the bottom side of the bracket tend to pull the bar more firmly into the bracket, increasing the strength of the grip on the pad.
The tank may have vertical L-shaped grooves 46 formed in side walls 26 near both the front and rear end walls. As shown in FIG. 1, the grooves 46 extend upwardly from the bottom wall 32. At least the rear grooves 46 extend the full height of the tank 12 and may be entered from either the top or bottom. Brackets 42 may be carried in grooves 46 by C-shaped carriers 48. Each carrier 48 may have a set screw 50 for clamping the bracket at the desired height in groove 46.
With reference to FIG. 3, tank 12 may be used in series with one or more trailing tandem tanks 52. Each tandem tank 52 is similar to tank 12, but lacking the depending bottom portion 18. Thus, tanks 52 have a substantially flat bottom surface over the entire bottom wall. These tanks otherwise may have their own nozzles 20, handles 36, pad fastening means 40, and mounting grooves 46. The tanks are held in tandem position by interconnecting means such as tethers or brackets, with joining brackets 54, shown in FIG. 4, being a preferred device. The joining brackets employ C-shaped carriers 48, as previously described, to connect the rear groove 46 of either lead tank 12 or tandem tank 52 to the front groove 46 of a trailing tandem tank 52. The joining brackets 54 may have an abutting spacer 56 opposing each carrier 48 to maintain a predetermined gap between juxtaposed tanks.
When tandem tanks are employed, each may carry within it a different liquid product. For example, if three tanks are employed, the lead tank 12 may carry a wetting agent. The center tank may carry a scrubbing agent, which may be water. The trailing tank may carry a bleaching agent. In addition to carrying different cleaning solutions, the tanks may employ different pads 22. For example, the pad on the center, scrubbing tank may be coarser, while the pad on the trailing, bleaching tank may be more absorbent.
According to one arrangement, the invention is inclusive of conveyor belt cleaning apparatus such as tank 52 having a forward end, rearward end, and two lateral sides, capable of carrying a supply of fluid, and having a bottom surface with a substantially planar surface. The tank 52 is characterized by the substantial absence of lateral sides depending below the planar bottom surface so as, in use, to be capable of overlying the top surface of a substantially straight run of conveyor belt. A fluid absorbent pad 22 is carried by the tank 52 over this bottom surface, and the tank further includes a means for applying fluid from the tank to the pad. A tether is connected to the tank 52 and, in use, is connectable to an external object to hold the tank in place over a moving conveyor belt. Thus, the cleaning apparatus may be merely placed over a conveyer belt and is retained against being transported along the belt by the tether.
According to another arrangement of the invention, the tank 52 is capable of containing fluid and has a bottom surface with a generally planar, pressure applying surface for, in use, overlying a substantially straight run of conveyor belt. The substantial absence of depending lateral sides enables the bottom surface to apply pressure to the top of a conveyor belt across the width of the bottom surface. The fluid dispensing means is capable of discharging fluid from within the tank to the proximity of the bottom surface of the tank. There is included a pad fastening means 40 for attaching a wiping pad longitudinally across the bottom surface of the tank. Also included is a tether for, in use, connecting the tank to an external object for preventing the tank from moving with the belt.
A single example of the specific dimensions of the belt cleaner may offer some insight into the construction of still other sizes. The tank 12 is about twenty-one inches from end wall to end wall. Bottom wall surface 38 is about one inch. Curved wall surface 18 is on a two inch radius and covers about a ninety degree arc. This wall surface smoothly joins surface 14 on a tangent, with the result that surface 14 is about eighteen inches long. The nozzles 20 are set back from the front wall 30 by about three and three-quarter inches. The height of the tank at the front wall is about eight inches, and the height at the rear wall is about six inches. In this configuration, the belt cleaner operates in a satisfactory manner.
In operation, the tank 12 is employed as a free-standing device that requires no special fixtures on the conveyor before being used on a typical, flat belt conveyor 60, FIG. 3. The tank is filled through filler cap 34 with any desired cleaning solution, as appropriate to the job. A clean pad 22 is installed in the pad carriers 40. Then the tank is placed over the end of the conveyor belt 60, with the belt rising over the end roller 62, as shown by the arrow in FIG. 3. The front end of the tank 12 extends beyond the end of the conveyor belt and depending surface 18 retains the tank against being transported along the conveyor on the belt.
Flat surface 16 is applied over the pad 22 to press the pad against the top surface of the belt. The cleaning solution is dispensed by gravity through orifices 20 into the pad near the front of the tank. The solution works its way toward the rear of the pad by absorption in the pad and by the wiping action of the conveyor belt against the pad. The weight of the tank is applied over the pad to provide scrubbing pressure, and the pad itself is rubbed by the surface of the belt to both apply the cleaning solution to the belt and to apply scrubbing friction.
Tests run with a single tank 12 in a food processing plant have shown that the belt cleaner 10 effectively cleans an entire belt with approximately eight minutes of belt operation. In that time, the belt is cleaned sufficiently to remove protein build-up and thus restore the typical white color. In addition, the belt passes USDA standards with swab culture tests. Use of the cleaner saves a considerable amount of labor and eliminates the need to hand scrub each belt. Furthermore, the belt cleaner 10 is economical in its use of cleaning chemicals, since it meters the chemicals and applies them uniformly. The typical splashing and waste of such chemicals, as is found with hand scrubbing, is prevented. Still further, safety is improved by elimination of chemical burns and other types of injury that sometimes occur during hand scrubbing operations.
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 regarded as falling within the scope of the invention as defined by the claims that follow.
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A free-standing cleaner (10) for conveyor belts (60) constitutes a tank (12) for holding fluid and having a removeable pad (22) attached across its bottom surface (14). Nozzles (20) in the bottom surface deliver the cleaning fluid to the pad (22). One longitudinal end (18) of the tank depends from the majority of the bottom surface (14) and hooks over the upstream end of the conveyor for anchoring the tank (12) against movement with the conveyor belt (60). Tandem tanks may be joined to the downstream end of the first tank for applying multiple cleaning fluids to the belt (60).
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This application is a continuation-in-part of U.S. patent application Ser. No. 08/104,302 filed on Aug. 9, 1993 now U.S. Pat No. 5,362,796 the entire disclosure of which is hereby incorporated by reference.
FIELD OF INVENTION
The present invention relates to the conversion of a raster image into a vector format, particularly to an apparatus and method for breaking contrast ties within a localized area of the image which enables the further step of defining color borders.
BACKGROUND OF THE INVENTION
Image processing generally refers to the manipulation of pictorial data using computers. Computer Aided Design (CAD) is one example of how computers are used to draft complex engineering drawings such as mechanical, architectural or electrical drawings. Other examples of image processing include the manipulation of still photographs or cinema to achieve various effects such as feature enhancement, three-dimensional rendering, or animation. However, the term “image processing” is not limited to pictures—it generally refers to the digitization and computer processing of any analog signal that represents something physical and perceptible in the world. An audio signal can be digitized and processed with computers to perform manipulations such as noise reduction or voice recognition; modulated electrical signals, such as telecommunications or cardiograms, can be digitized and processed by computers to extract pertinent information, and so on. The common factor in image processing is the need to digitize the continuous-time analog signal into a discrete-time digital signal that can be operated on by computers using boolean mathematics implemented in transistor logic circuits.
A common format for storing and manipulating digitized signals is simply to represent the digital data as a bit-map of pixels, where each pixel represents a particular characteristic (e.g., magnitude or color) of the analog signal. Typically, a picture is digitized into a bit-map of individual pixels where each pixel represents a color of the image in a very small, localized area. When the pixels are displayed as a congregation, the original picture appears without loss of perception to the human eye as long as there is sufficient resolution (number of pixels) both in spatial and color contexts. A black and white picture can be represented with one-bit pixels, where the state of the bit (0 or 1) represents the two colors, black and white. To digitize a picture comprising multiple colors, each pixel is represented using n-bits such that each pixel can take on one of 2 n different colors. The process of converting an analog image into a bit-map image is referred to as “rasterizing” the image.
There are several well known problems with raster images that limit or inhibit the full potential of computer manipulation. The amount of memory necessary to store a large photograph having many colors (thousands or even millions of colors) can be immense, and the problem is exacerbated when attempting to digitize a series of photographs such as a scene in a movie. Not only do raster images require large amounts of storage memory, but processing such a large amount of data can be slow, particularly when attempting to transfer raster images over a network such as the internet.
Another problem inherent with the raster format is an inability to perform many of the desired image processing functions, such as three-dimensional rendering or animation. Even a simple operation such as magnifying the image results in a granular distortion caused by enlarging the pixels of the image as illustrated in FIG. 1 . It is possible to perform digital signal processing when magnifying a raster image by effectively re-sampling the image to attenuate the granular distortion that occurs due to the fixed resolution. However, this process only reduces the granular distortion rather than eliminate it. Furthermore, resampling the image is time consuming and not practical in many applications. Other operations, such as electronic focusing and automatic imaging, are simply not possible when the image is stored in a raster format.
The alternative is to convert the raster image into a mathematical format known as vectors. A vector is a mathematical description of the image which is not constrained by a fixed resolution as with raster data. Furthermore, vectors allow for a much more diverse range of image manipulations due to the mathematical representation of the image. A simple example of a vector is a line beginning at a particular X,Y point in a cartesian plane and ending at another X,Y point in that plane. To date, however, converting raster images into a series of linear vectors has been largely unsuccessful. This is due to the immense number of different possible patterns that raster images can form. For example, a 3 by 3 pixel matrix of a nine color picture can take on about 21,000 different possible patterns. Each possibility must be accounted for when converting the image into a set of linear vectors. If just one more pixel is added to the matrix, the complexity increases exponentially. Consequently, techniques for converting raster images into linear vectors normally operate on only a small section of the image at a time. The problem with this approach is that the resulting vectorized image appears fragmented due to discontinuities when the individual sections are combined.
There have been other attempts to convert a raster image using vectors that are more abstract mathematical representations. For example, a technique referred to as wavelets attempts to represent the raster image as a series of interconnected mathematical equations. With wavelets, a particular feature of the image might be represented using a number of polynomials which approximate the feature contours. The problem with this technique, however, is that the equations become extremely complex unless the operation is constrained to only a small group of pixels. But again, distortion due to fragmentation occurs when attempting to combine the individual equations into a complete image. A similar distortion occurs with using fractals, a method where the image is represented using a library of different shapes which approximate the various features of an image. Similar to wavelets, however, discontinuities occur with fractals when attempting to combine the individual shapes which causes distortion due to fragmentation.
Another known method for raster to vector conversion, referred to as the Automatic Bezier Curve technique, draws Bezier curves through tags that are placed somewhat arbitrarily on the image. Unlike fractals or wavelets, Bezier techniques cannot convert complicated pictures without losing information. On the other hand, the Bezier technique can sequence equations together over a large number of pixels which reduces the amount of fragmentation typically associated with other techniques.
The Bezier method is illustrated in FIG. 1 B. The first step is to identify the color borders for each feature in the image, and then to place somewhat arbitrarily tags on the borders. These tags then become the new representation of the image. When the image is to be displayed, these tags are converted into a rasterized format by drawing Bezier curves through the tags as shown in FIG. 1 B. The problem with the Bezier conversion technique is that it has a hard time dealing with complicated images. When tags are placed some definition is lost. In a complex image, many tags are placed resulting in a great deal of loss in picture definition. Even more severe is that the Bezier technique only looks at simple borders. In complex images, there is usually an interaction of shades that catch the eye. The Bezier curve technique treats all of these different shades as either borders or points. This often results in a vector representation that is more complicated than a raster representation; in effect, the Bezier solution can actually be worse than the problem.
There have been other attempts to represent the feature contours of an image using mathematics capable of spanning more than just a small area on the image. For example, U.S. Pat. No. 4,777,651 discloses a method of pixel-to-vector conversion where the line and edge features of the image are converted into a series of continous line segments. The line segments are generated by connecting a series of slope elements which follow the contour of a line or edge in the image. The slope elements are generated by scanning a 3×3 array of pixels through the raster image data and generating a slope vector for each pixel. The 3×3 array of pixels are evaluated to determine the slope of the image contour at the current pixel. The slope elements are then connected to form continous line segments that represent the contours of the image. The line segments are further processed to generate the vectors that can be understood and manipulated using computers.
The process of sequencing a series of slope elements into line segments which represent the contours of an image has been known in the art as early as 1961. See H. Freeman, “On the Encoding of Arbitrary Geometric Configurations,” IRE Transactions, EC-10(2), June 1961, 260-268. Freeman describes the technique of scanning a square matrix through raster data to generate a slope element for each pixel, and then connecting the slope elements into line segments which represent the image contours.
There are drawbacks with the aforementioned prior art methods of sequencing slope elements into line segments to represent the image contours. Namely, U.S. Pat. No. 4,777,651 is capable of sequencing line segments for contours of only black and white images. Thus, this technique cannot be applied to color images without first converting the image into black and white which means the color information is lost. Furthermore, the list of square matrices for generating the slope elements shown in FIG. 9 is not exhaustive and, consequently, fragmentation can occur when attempting to generate and connect the line segments. Still further, sequencing the line segments using only the slope values does not provide optimal information for generating the final vectors which ultimately represent the image. In other words, the vectors generated using this technique are not optimal because there is not enough information provided in line segments comprised of only slope values. Also, these techniques do not address the optical illusion which can manifest in images where the contrast in certain features determines or enables perception.
There is, therefore, a need for an improved method and apparatus for converting the contours or borders of a raster image into a more abstract mathematical representation which can be converted into a vector format without fragmenting the image. More specifically, it is an object of the present invention to convert the color borders of a raster image into a mathematical representation, wherein the raster image is comprised of pixels representing more colors than just black and white. Another object of the present invention is to provide enough information in the border representation of the image so as to optimize the vectors ultimately generated from this information. Still another object of the present invention is to identify and resolve contrast conflicts in the various features of an image in order to avoid misperceiving the vectorized image when converted back into a raster format.
SUMMARY OF THE INVENTION
The present invention discloses a method and apparatus for converting the color borders of a raster image into a more abstract mathematical representation that can be converted into a vector format without significantly fragmenting the image. The invention involves scanning a neighborhood of cells in the form of a square matrix through the raster image in order to generate a surface string (or an indicia thereof) representing the color border at each pixel, and then to sequence the surface strings into string sequences which represent the color borders.
The neighborhood of cells comprise a target cell (e.g., a center cell) and a number of surrounding perimeter cells. Each cell corresponds to a pixel in the raster image. A color value is assigned to the perimeter cells indicating whether the pixel represented by the perimeter cell is the same or different in color from the pixel represented by the target cell. Thus, there is a limited number of different color combinations that are possible in a neighborhood (e.g., 256 in a 3×3 neighborhood).
As the neighborhood is scanned through the raster image, the color values of the cells are changed according to the color of the perimeter pixels relative to the target pixel. The resulting neighborhood is then used to index a neighborhood table comprising all the possible different color combinations, that is, all the different possible neighborhoods. The neighborhood table outputs up to six different surface strings which represent the color border or borders which pass through the current neighborhood of pixels comprising the current target pixel. There is a limited number of possible surface strings that are necessary to account for all the different possible color combinations in a neighborhood. However, a significant aspect of the present invention is to provide an exhaustive set of surface strings that can account for all the possible arrangements of color borders in a raster image. In the preferred embodiment, a neighborhood comprises a 3×3 square matrix of cells which results in an exhaustive set of 58 surface strings.
Each surface string has associated with it a receive slope and a send slope which represent the slope of a corresponding color border passing through the neighborhood. The receive and send slopes are used by a string sequencer to connect the surface strings into a contiguous string sequence representing a color border in the image. Although the receive and send slopes are used to connect the surface strings, the string sequencer actually sequences numbers which identify the surface strings rather than merely sequencing slope values as is done in the aforementioned prior art techniques. Sequencing surface string IDs, as opposed to merely sequencing slopes, provides additional information about each surface string which can be used to generate vectors that better represent the raster image.
Another enabling aspect of the present invention is to sequence the surface strings according to a predetermined criteria. In the preferred embodiment, a priority is assigned to surface strings based on their location in the image and their type. Northern surface strings have the highest priority meaning that a string sequence will begin with the most northern surface string in the image, and the sequencing of strings will always progresses from north to south—never from south to north. The next highest priority is assigned to a special type of surface string referred to as a “protruding corner” surface string. That is, a “protruding corner” surface string has priority over a “square corner” surface string which has priority over a “step” surface string. So if two surface strings are at the same northern position in an image, the surface string type determines which surface string to begin a string sequence and in which direction to sequence. If two surface strings at the same northern location are of the same type, then the western surface string has priority over the eastern surface string.
To enable the string sequencing of color images, the present invention identifies and resolves contrast conflicts in the image features in order to avoid misperceiving the vectorized image when converted back into a raster format. A contrast conflict occurs when there is a “contrast tie” between overlapping features of the image. The feature that would normally be perceived as the dominant feature breaks the contrast tie so that when the vector image is reconstructed, the dominate feature appears in the foreground of the image while the recessive feature appears in the background. A contrast tie detector (CTD) performs a set of comparisons on the raw pixel data to detect the occurrence of a contrast tie, and a contrast tie breaker (CTB) performs another set of comparisons on the raw pixel data to break the contrast tie. A contrast tie is broken by modifying a color identifier of a perimeter pixel relative to the color value of a target pixel, thereby enabling the correct string sequencing of color borders. These and other aspects and advantages of the present invention will be better understood by reading the following detailed description of the invention in conjunction with the following drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A illustrates the granular distortion that occurs when magnifying a raster image.
FIG. 1B illustrates a prior art Bezier curve technique for converting raster images into vectors.
FIG. 2 is a block diagram of the elements for defining the color borders of a raster image according to the aspects of the present invention.
FIG. 3 shows an exhaustive set of surface strings corresponding to a neighborhood of cells representing pixels of the raster image, wherein the surface strings are connected into a string sequence to define a color border.
FIG. 4A shows a neighborhood of cells comprising a target cell surrounded by perimeter cells with color values of X, Y, or Z indicating that the color of the representative pixel in the image is either not considered (X), the same color (Y) as the pixel represented by the target cell, or a different color (Z) than the pixel representing the target cell.
FIG. 4B shows the possible slope values for the send and receive slopes of a surface string.
FIG. 5A shows a color raster image comprising a simple feature and the corresponding string sequences generated by the present invention.
FIG. 5B shows a color raster image with more complex features and the corresponding string sequences generated by the present invention.
FIGS. 6A-6C illustrate a contrast conflict (contrast tie) in a raster image and how the present invention resolves the conflict.
FIG. 7A shows the four quadrants in a 3×3 array of pixels that are processed to detect a contrast tie.
FIG. 7B shows the four quadrants in a 3×3 array of pixels and surrounding pixels that are processed to break a contrast tie.
FIG. 7C illustrates an enhancement to the aspect of breaking contrast ties wherein the corner pixels of the 4×34 array of pixels are also evaluated.
FIG. 7D illustrates yet another enhancement to breaking contrast ties wherein the pixels evaluated is expanded to a 5×5 array of pixels.
FIGS. 8A-8D illustrate the pixel bit maps evaluated to break a contrast tie in an example raster image.
FIG. 9 shows a perceived embodiment of the present invention comprising a system memory for storing a computer program which implements the aspects of the present, and a data processor for executing the steps of the computer program.
FIG. 10 illustrates an alternative embodiment of the present invention: an image processing integrated circuit comprising logic circuits for implementing the aspects of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 2 shows a block diagram of the elements used to define the color borders of a raster image according to the aspects of the present invention. The raster image data 2 that is to be converted into a vector format 4 can come from many different alternative sources. For example, it may be generated by illuminating a photograph with a light source and detecting the reflected light with a charge-coupled-device (CCD). A CCD is typically formed of an array of individual photosensitive cells which detect an intensity or brightness of the light. Thus, the output of the CCD is an array of pixels which represent a portion of the raster image bit map. As the light source is scanned over the photograph, the pixels output by the CCD are concatenated to form the entire raster image. Color in the photograph can be detected by employing red-green-blue (RGB) filters in front of three respective CCDs, and then combining the outputs of the CCDs into an n-bit pixel that can represent one of 2 n colors.
The aspects of the present invention are not limited to raster images that represent photographs. The present invention can also convert other digitized signals, such as audio or communication signals, into a vector format for more efficient and effective processing by computers. Such signals are typically generated by a transducer (e.g., a microphone, antenna, recording head, etc.) which senses and transduces into an electrical signal some physical manifestation, such as an acoustic or electromagnetic wave. Typically, the electrical signal is then digitized and converted into a raster format using an analog-to-digital (A/D) converter.
The raster image data 2 processed by the present invention can be generated in real time meaning that the raster data can be converted directly into a vector format as the analog signal is being digitized. Alternatively, the raster image data 2 may be stored on a recording medium, such as a magnetic or optical disc, and processed at a later time by the present invention to define the color borders and ultimately convert the raster data into a vector format.
The raster image data 2 , whether processed in real time or read from a storage medium, is processed by a contrast breaker 3 which resolves “contrast ties” in the image features. This aspect of the present invention is described in greater detail below with reference to FIGS. 6-8. After breaking contrast ties, the raster data is input into a neighborhood scanner 8 which scans through the raster data and process the image pixels in a square array referred to as a neighborhood. In the preferred embodiment, the neighborhood represents a 3×3 array of image pixels.
The scanning processes is understood with reference to FIG. 5A which shows the pixels of a raster image and a neighborhood 10 a overlaying the image such that the first pixel 12 of the image is in the center of the neighborhood 10 a (the cells of the neighborhood 10 a laying outside the image are assigned the color Y). After processing this array of pixels, the neighborhood 10 a is shifted to the right by one pixel so that the next pixel 14 of the image is in the center of the neighborhood 10 a. This process continues until the neighborhood has passed over every pixel in the image ending at neighborhood 10 d.
In the present invention, the neighborhood of pixels are not processed directly as in the prior art. Instead, the pixels are converted into corresponding cells which comprise a color value as shown in FIG. 4 A. The neighborhood of cells comprises a target cell (in this case the center cell) denoted T and a number of perimeter cells denoted P 0-7 . The color values that can be assigned to each cell are Y and Z. The color Y indicates that the color of the pixel represented by the cell is the same color as the pixel represented by the target cell (the color of the target cell T is always Y), and the color Z indicates that the color of the pixel represented by the cell has a different color than the pixel represented by the target cell. Thus, in a 3×3 array of cells with the target cell always having a color value of Y, there are 2 8 or 256 different possible color combinations for the perimeter cells P 0-7 .
Referring again to FIG. 2, the neighborhood of cells 16 generated for each pixel in the image is used as an address into a neighborhood lookup table 18 . The content of the neighborhood lookup table is shown below:
Neighborhood Lookup Table
SURFACE
STRINGS
ADR
P 0 P 1 P 2
P 3 T P 4
P 5 P 6 P 7
00,00,00,00,00,00;
0
Z Z Z
Z Y Z
Z Z Z
01,02,00,00,00,00;
1
Z Z Z
Z Y Z
Z Z Y
03,04,00,00,00,00;
2
Z Z Z
Z Y Z
Z Y Z
03,02,00,00,00,00;
3
Z Z Z
Z Y Z
Z Y Y
05,06,00,00,00,00;
4
Z Z Z
Z Y Z
Y Z Z
05,07,46,02,00,00;
5
Z Z Z
Z Y Z
Y Z Y
05,04,00,00,00,00;
6
Z Z Z
Z Y Z
Y Y Z
05,02,00,00,00,00;
7
Z Z Z
Z Y Z
Y Y Y
10,00,00,00,00,00;
8
Z Z Z
Z Y Y
Z Z Z
09,00,00,00,00,00;
9
Z Z Z
Z Y Y
Z Z Y
15,00,00,00,00,00;
10
Z Z Z
Z Y Y
Z Y Z
15,00,00,00,00,00;
11
Z Z Z
Z Y Y
Z Y Y
12,13,00,00,00,00;
12
Z Z Z
Z Y Y
Y Z Z
12,07,46,00,00,00;
13
Z Z Z
Z Y Y
Y Z Y
12,00,00,00,00,00;
14
Z Z Z
Z Y Y
Y Y Z
12,00,00,00,00,00;
15
Z Z Z
Z Y Y
Y Y Y
14,00,00,00,00,00;
16
Z Z Z
Y Y Z
Z Z Z
17,16,00,00,00,00;
17
Z Z Z
Y Y Z
Z Z Y
18,00,00,00,00,00;
18
Z Z Z
Y Y Z
Z Y Z
16,00,00,00,00,00;
19
Z Z Z
Y Y Z
Z Y Y
41,00,00,00,00,00;
20
Z Z Z
Y Y Z
Y Z Z
07,46,16,00,00,00;
21
Z Z Z
Y Y Z
Y Z Y
18,00,00,00,00,00;
22
Z Z Z
Y Y Z
Y Y Z
16,00,00,00,00,00;
23
Z Z Z
Y Y Z
Y Y Y
56,54,00,00,00,00;
24
Z Z Z
Y Y Y
Z Z Z
17,54,00,00,00,00;
25
Z Z Z
Y Y Y
Z Z Y
54,00,00,00,00,00;
26
Z Z Z
Y Y Y
Z Y Z
54,00,00,00,00,00;
27
Z Z Z
Y Y Y
Z Y Y
13,54,00,00,00,00;
28
Z Z Z
Y Y Y
Y Z Z
07,46,54,00,00,00;
29
Z Z Z
Y Y Y
Y Z Y
54,00,00,00,00,00;
30
Z Z Z
Y Y Y
Y Y Z
54,00,00,00,00,00;
31
Z Z Z
Y Y Y
Y Y Y
20,21,00,00,00,00;
32
Z Z Y
Z Y Z
Z Z Z
22,23,00,00,00,00;
33
Z Z Y
Z Y Z
Z Z Y
24,25,00,00,00,00;
34
Z Z Y
Z Y Z
Z Y Z
24,23,00,00,00,00;
35
Z Z Y
Z Y Z
Z Y Y
53,48,00,00,00,00;
36
Z Z Y
Z Y Z
Y Z Z
53,07,46,23,00,00;
37
Z Z Y
Z Y Z
Y Z Y
53,25,00,00,00,00;
38
Z Z Y
Z Y Z
Y Y Z
53,23,00,00,00,00;
39
Z Z Y
Z Y Z
Y Y Y
28,00,00,00,00,00;
40
Z Z Y
Z Y Y
Z Z Z
22,00,00,00,00,00;
41
Z Z Y
Z Y Y
Z Z Y
24,00,00,00,00,00;
42
Z Z Y
Z Y Y
Z Y Z
24,00,00,00,00,00;
43
Z Z Y
Z Y Y
Z Y Y
53,13,00,00,00,00;
44
Z Z Y
Z Y Y
Y Z Z
53,07,46,00 00,00;
45
Z Z Y
Z Y Y
Y Z Y
53,00,00,00,00,00;
46
Z Z Y
Z Y Y
Y Y Z
53,00,00,00,00,00;
47
Z Z Y
Z Y Y
Y Y Y
30,27,00,00,00,00;
48
Z Z Y
Y Y Z
Z Z Z
30,23,17,00,00,00;
49
Z Z Y
Y Y Z
Z Z Y
30,25,00,00,00,00;
50
Z Z Y
Y Y Z
Z Y Z
30,23,00,00,00,00;
51
Z Z Y
Y Y Z
Z Y Y
30,48,00,00,00,00;
52
Z Z Y
Y Y Z
Y Z Z
30,07,46,23,00,00;
53
Z Z Y
Y Y Z
Y Z Y
30,25,00,00,00,00;
54
Z Z Y
Y Y Z
Y Y Z
30,23,00,00,00,00;
55
Z Z Y
Y Y Z
Y Y Y
30,56,00,00,00,00;
56
Z Z Y
Y Y Y
Z Z Z
30,17,00,00,00,00;
57
Z Z Y
Y Y Y
Z Z Y
30,00,00,00,00,00;
58
Z Z Y
Y Y Y
Z Y Z
30,00,00,00,00,00;
59
Z Z Y
Y Y Y
Z Y Y
30,13,00,00,00,00;
60
Z Z Y
Y Y Y
Y Z Z
30,07,46,00,00,00;
61
Z Z Y
Y Y Y
Y Z Y
30,00,00,00,00,00;
62
Z Z Y
Y Y Y
Y Y Z
30,00,00,00,00,00;
63
Z Z Y
Y Y Y
Y Y Y
32,52,00,00,00,00;
64
Z Y Z
Z Y Z
Z Z Z
34,35,00,00,00,00;
65
Z Y Z
Z Y Z
Z Z Y
58,57,00,00,00,00;
66
Z Y Z
Z Y Z
Z Y Z
58,35,00,00,00,00;
67
Z Y Z
Z Y Z
Z Y Y
36,37,00,00,00,00;
68
Z Y Z
Z Y Z
Y Z Z
36,07,46,35,00,00;
69
Z Y Z
Z Y Z
Y Z Y
36,57,00,00,00,00;
70
Z Y Z
Z Y Z
Y Y Z
36,35,00,00,00,00;
71
Z Y Z
Z Y Z
Y Y Y
38,00,00,00,00,00;
72
Z Y Z
Z Y Y
Z Z Z
34,00,00,00,00,00;
73
Z Y Z
Z Y Y
Z Z Y
58,00,00,00,00,00;
74
Z Y Z
Z Y Y
Z Y Z
58,00,00,00,00,00;
75
Z Y Z
Z Y Y
Z Y Y
36,13,00,00,00,00;
76
Z Y Z
Z Y Y
Y Z Z
36,07,46,00,00,00;
77
Z Y Z
Z Y Y
Y Z Y
36,00,00,00,00,00;
78
Z Y Z
Z Y Y
Y Y Z
36,00,00,00,00,00;
79
Z Y Z
Z Y Y
Y Y Y
33,00,00,00,00,00;
80
Z Y Z
Y Y Z
Z Z Z
17,35,00,00,00,00;
81
Z Y Z
Y Y Z
Z Z Y
57,00,00,00,00,00;
82
Z Y Z
Y Y Z
Z Y Z
35,00,00,00,00,00;
83
Z Y Z
Y Y Z
Z Y Y
37,00,00,00,00,00;
84
Z Y Z
Y Y Z
Y Z Z
07,46,35,00,00,00;
85
Z Y Z
Y Y Z
Y Z Y
57,00,00,00,00,00;
86
Z Y Z
Y Y Z
Y Y Z
35,00,00,00,00,00;
87
Z Y Z
Y Y Z
Y Y Y
56,00,00,00,00,00;
88
Z Y Z
Y Y Y
Z Z Z
17,00,00,00,00,00;
89
Z Y Z
Y Y Y
Z Z Y
00,00,00,00,00,00;
90
Z Y Z
Y Y Y
Z Y Z
00,00,00,00,00,00;
91
Z Y Z
Y Y Y
Z Y Y
13,00,00,00,00 00;
92
Z Y Z
Y Y Y
Y Z Z
07,46,00,00,00,00;
93
Z Y Z
Y Y Y
Y Z Y
00,00,00,00,00,00;
94
Z Y Z
Y Y Y
Y Y Z
00,00,00,00,00,00;
95
Z Y Z
Y Y Y
Y Y Y
32,21,00,00,00,00;
96
Z Y Y
Z Y Z
Z Z Z
34,23,00,00,00,00;
97
Z Y Y
Z Y Z
Z Z Y
58,25,00 00,00,00;
98
Z Y Y
Z Y Z
Z Y Z
58,23,00,00,00,00;
99
Z Y Y
Z Y Z
Z Y Y
36,48,00,00,00,00;
100
Z Y Y
Z Y Z
Y Z Z
36,07,46,23,00,00;
101
Z Y Y
Z Y Z
Y Z Y
36,25,00,00,00,00;
102
Z Y Y
Z Y Z
Y Y Z
36,23,00,00,00,00;
103
Z Y Y
Z Y Z
Y Y Y
38,00,00,00,00,00;
104
Z Y Y
Z Y Y
Z Z Z
34,00,00,00,00,00;
105
Z Y Y
Z Y Y
Z Z Y
58,00,00,00,00,00;
106
Z Y Y
Z Y Y
Z Y Z
58,00,00,00,00,00;
107
Z Y Y
Z Y Y
Z Y Y
36,13,00,00,00,00;
108
Z Y Y
Z Y Y
Y Z Z
36,07,46,00,00,00;
109
Z Y Y
Z Y Y
Y Z Y
36,00,00,00,00,00;
110
Z Y Y
Z Y Y
Y Y Z
36,00,00,00,00,00;
111
Z Y Y
Z Y Y
Y Y Y
27,00,00,00,00,00;
112
Z Y Y
Y Y Z
Z Z Z
17,23,00,00,00,00;
113
Z Y Y
Y Y Z
Z Z Y
25,00,00,00,00,00;
114
Z Y Y
Y Y Z
Z Y Z
23,00,00,00,00,00;
115
Z Y Y
Y Y Z
Z Y Y
48,00,00,00,00,00;
116
Z Y Y
Y Y Z
Y Z Z
07,46,23,00,00,00;
117
Z Y Y
Y Y Z
Y Z Y
25,00,00,00,00,00;
118
Z Y Y
Y Y Z
Y Y Z
23,00,00,00,00,00;
119
Z Y Y
Y Y Z
Y Y Y
56,00,00,00,00,00;
120
Z Y Y
Y Y Y
Z Z Z
17,00,00,00,00,00;
121
Z Y Y
Y Y Y
Z Z Y
00,00,00,00,00,00;
122
Z Y Y
Y Y Y
Z Y Z
00,00,00,00,00,00;
123
Z Y Y
Y Y Y
Z Y Y
13,00,00,00,00,00;
124
Z Y Y
Y Y Y
Y Z Z
07,46,00,00,00,00;
125
Z Y Y
Y Y Y
Y Z Y
00,00,00,00,00,00;
126
Z Y Y
Y Y Y
Y Y Z
00,00,00,00,00,00;
127
Z Y Y
Y Y Y
Y Y Y
42,43,00,00,00,00;
128
Y Z Z
Z Y Z
Z Z Z
47,45,00,00,00,00;
129
Y Z Z
Z Y Z
Z Z Y
44,40,00,00,00,00;
130
Y Z Z
Z Y Z
Z Y Z
44,45,00,00,00,00;
131
Y Z Z
Z Y Z
Z Y Y
39,31,00,00,00,00;
132
Y Z Z
Z Y Z
Y Z Z
39,07,46,45,00,00;
133
Y Z Z
Z Y Z
Y Z Y
39,40,00,00,00,00;
134
Y Z Z
Z Y Z
Y Y Z
39,45,00,00,00,00;
135
Y Z Z
Z Y Z
Y Y Y
29,11,00,00,00,00;
136
Y Z Z
Z Y Y
Z Z Z
47,11,00,00,00,00;
137
Y Z Z
Z Y Y
Z Z Y
44,11,00,00,00,00;
138
Y Z Z
Z Y Y
Z Y Z
44,11,00,00,00,00;
139
Y Z Z
Z Y Y
Z Y Y
39,13,11,00,00,00;
140
Y Z Z
Z Y Y
Y Z Z
39,07,46,11,00,00;
141
Y Z Z
Z Y Y
Y Z Y
39,11,00,00,00,00;
142
Y Z Z
Z Y Y
Y Y Z
39,11,00,00,00,00;
143
Y Z Z
Z Y Y
Y Y Y
19,00,00,00,00,00;
144
Y Z Z
Y Y Z
Z Z Z
17,45,00,00,00,00;
145
Y Z Z
Y Y Z
Z Z Y
40,00,00,00,00,00;
146
Y Z Z
Y Y Z
Z Y Z
45,00,00,00,00,00;
147
Y Z Z
Y Y Z
Z Y Y
31,00,00,00,00,00;
148
Y Z Z
Y Y Z
Y Z Z
07,46,45,00,00,00;
149
Y Z Z
Y Y Z
Y Z Y
40,00,00,00,00,00;
150
Y Z Z
Y Y Z
Y Y Z
45,00,00,00,00,00;
151
Y Z Z
Y Y Z
Y Y Y
11,56,00,00,00,00;
152
Y Z Z
Y Y Y
Z Z Z
17,11,00,00,00,00;
153
Y Z Z
Y Y Y
Z Z Y
11,00,00,00,00,00;
154
Y Z Z
Y Y Y
Z Y Z
11,00,00,00,00,00;
155
Y Z Z
Y Y Y
Z Y Y
13,11,00,00 00 00;
156
Y Z Z
Y Y Y
Y Z Z
07,46,11,00,00,00;
157
Y Z Z
Y Y Y
Y Z Y
11,00,00,00,00,00;
158
Y Z Z
Y Y Y
Y Y Z
11,00,00,00,00,00;
159
Y Z Z
Y Y Y
Y Y Y
42,08,26,21,00,00;
160
Y Z Y
Z Y Z
Z Z Z
47,08,26,23,00,00;
161
Y Z Y
Z Y Z
Z Z Y
44,08,26,25,00,00;
162
Y Z Y
Z Y Z
Z Y Z
44,08,26,23 00,00;
163
Y Z Y
Z Y Z
Z Y Y
39,08,26,48,00,00;
164
Y Z Y
Z Y Z
Y Z Z
39,08,26,07,46,23;
165
Y Z Y
Z Y Z
Y Z Y
39,08,26,25,00,00;
166
Y Z Y
Z Y Z
Y Y Z
39,08,26,23,00,00;
167
Y Z Y
Z Y Z
Y Y Y
29,08,26,00,00,00;
168
Y Z Y
Z Y Y
Z Z Z
47,08,26,00,00,00;
169
Y Z Y
Z Y Y
Z Z Y
44,08,26,00,00,00;
170
Y Z Y
Z Y Y
Z Y Z
44,08,26,00,00,00;
171
Y Z Y
Z Y Y
Z Y Y
39,08,26,13,00,00;
172
Y Z Y
Z Y Y
Y Z Z
39,08,26,07,46,00;
173
Y Z Y
Z Y Y
Y Z Y
39,08,26,00,00,00;
174
Y Z Y
Z Y Y
Y Y Z
39,08,26,00,00,00;
175
Y Z Y
Z Y Y
Y Y Y
08,26,27,00,00,00;
176
Y Z Y
Y Y Z
Z Z Z
08,26,17,23,00,00;
177
Y Z Y
Y Y Z
Z Z Y
08,26,25,00,00,00;
178
Y Z Y
Y Y Z
Z Y Z
08,26,23,00,00,00;
179
Y Z Y
Y Y Z
Z Y Y
08,26,48,00,00,00;
180
Y Z Y
Y Y Z
Y Z Z
08,26,07,46,23,00;
181
Y Z Y
Y Y Z
Y Z Y
08,26,25,00,00,00;
182
Y Z Y
Y Y Z
Y Y Z
08,26,23,00,00,00;
183
Y Z Y
Y Y Z
Y Y Y
08,26,56,00,00,00;
184
Y Z Y
Y Y Y
Z Z Z
08,26,17,00,00,00;
185
Y Z Y
Y Y Y
Z Z Y
08,26,00,00,00,00;
186
Y Z Y
Y Y Y
Z Y Z
08,26,00,00 00,00;
187
Y Z Y
Y Y Y
Z Y Y
08,26,13,00,00,00;
188
Y Z Y
Y Y Y
Y Z Z
08,26,07,46,00,00;
189
Y Z Y
Y Y Y
Y Z Y
08,26,00,00,00,00;
190
Y Z Y
Y Y Y
Y Y Z
08,26,00,00,00,00;
191
Y Z Y
Y Y Y
Y Y Y
42,52,00,00,00,00;
192
Y Y Z
Z Y Z
Z Z Z
47,35,00,00,00,00;
193
Y Y Z
Z Y Z
Z Z Y
44,57,00,00,00,00;
194
Y Y Z
Z Y Z
Z Y Z
44,35,00,00,00,00;
195
Y Y Z
Z Y Z
Z Y Y
39,37,00,00,00,00;
196
Y Y Z
Z Y Z
Y Z Z
39,07,46,35,00,00;
197
Y Y Z
Z Y Z
Y Z Y
39,57,00,00,00,00;
198
Y Y Z
Z Y Z
Y Y Z
39,35,00,00,00,00;
199
Y Y Z
Z Y Z
Y Y Y
29,00,00,00,00,00;
200
Y Y Z
Z Y Y
Z Z Z
47,00,00,00,00,00;
201
Y Y Z
Z Y Y
Z Z Y
44,00,00,00,00,00;
202
Y Y Z
Z Y Y
Z Y Z
44,00,00,00,00,00;
203
Y Y Z
Z Y Y
Z Y Y
39,13,00,00,00,00;
204
Y Y Z
Z Y Y
Y Z Z
39,07,46,00,00,00;
205
Y Y Z
Z Y Y
Y Z Y
39,00,00,00,00,00;
206
Y Y Z
Z Y Y
Y Y Z
39,00,00,00,00,00;
207
Y Y Z
Z Y Y
Y Y Y
33,00,00,00,00,00;
208
Y Y Z
Y Y Z
Z Z Z
17,35,00,00,00,00;
209
Y Y Z
Y Y Z
Z Z Y
57,00,00,00,00,00;
210
Y Y Z
Y Y Z
Z Y Z
35,00,00,00,00,00;
211
Y Y Z
Y Y Z
Z Y Y
37,00,00,00,00,00;
212
Y Y Z
Y Y Z
Y Z Z
07,46,35,00,00,00;
213
Y Y Z
Y Y Z
Y Z Y
57,00,00,00,00,00;
214
Y Y Z
Y Y Z
Y Y Z
35,00,00,00,00,00;
215
Y Y Z
Y Y Z
Y Y Y
56,00,00,00,00,00;
216
Y Y Z
Y Y Y
Z Z Z
17,00,00,00,00,00;
217
Y Y Z
Y Y Y
Z Z Y
00,00,00,00,00,00;
218
Y Y Z
Y Y Y
Z Y Z
00,00,00,00,00,00;
219
Y Y Z
Y Y Y
Z Y Y
13,00,00,00,00,00;
220
Y Y Z
Y Y Y
Y Z Z
07,46,00,00,00,00;
221
Y Y Z
Y Y Y
Y Z Y
00,00,00,00,00,00;
222
Y Y Z
Y Y Y
Y Y Z
00,00,00,00,00,00;
223
Y Y Z
Y Y Y
Y Y Y
42,21,00,00,00,00;
224
Y Y Y
Z Y Z
Z Z Z
47,23,00,00,00,00;
225
Y Y Y
Z Y Z
Z Z Y
44,25,00,00,00,00;
226
Y Y Y
Z Y Z
Z Y Z
44,23,00,00,00,00;
227
Y Y Y
Z Y Z
Z Y Y
39,48,00,00,00,00;
228
Y Y Y
Z Y Z
Y Z Z
39,07,46,23,00,00;
229
Y Y Y
Z Y Z
Y Z Y
39,25,00,00,00,00;
230
Y Y Y
Z Y Z
Y Y Z
39,23,00,00,00,00;
231
Y Y Y
Z Y Z
Y Y Y
29,00,00,00,00,00;
232
Y Y Y
Z Y Y
Z Z Z
47,00,00,00,00,00;
233
Y Y Y
Z Y Y
Z Z Y
44,00,00,00,00,00;
234
Y Y Y
Z Y Y
Z Y Z
44,00,00,00,00,00;
235
Y Y Y
Z Y Y
Z Y Y
39,13,00,00,00,00;
236
Y Y Y
Z Y Y
Y Z Z
39,07,46,00,00,00;
237
Y Y Y
Z Y Y
Y Z Y
39,00,00,00,00,00;
238
Y Y Y
Z Y Y
Y Y Z
39,00,00,00,00,00;
239
Y Y Y
Z Y Y
Y Y Y
27,00,00,00,00,00;
240
Y Y Y
Y Y Z
Z Z Z
17,23,00,00,00,00;
241
Y Y Y
Y Y Z
Z Z Y
25,00,00,00,00,00;
242
Y Y Y
Y Y Z
Z Y Z
23,00,00,00,00,00;
243
Y Y Y
Y Y Z
Z Y Y
48,00,00,00,00,00;
244
Y Y Y
Y Y Z
Y Z Z
07,46,23,00,00,00;
245
Y Y Y
Y Y Z
Y Z Y
25,00,00,00,00,00;
246
Y Y Y
Y Y Z
Y Y Z
23,00,00,00,00,00;
247
Y Y Y
Y Y Z
Y Y Y
56,00,00,00,00,00;
248
Y Y Y
Y Y Y
Z Z Z
17,00,00,00,00,00;
249
Y Y Y
Y Y Y
Z Z Y
00,00,00,00,00,00;
250
Y Y Y
Y Y Y
Z Y Z
00,00,00,00,00,00;
251
Y Y Y
Y Y Y
Z Y Y
13,00,00,00,00,00;
252
Y Y Y
Y Y Y
Y Z Z
07,46,00,00,00,00;
253
Y Y Y
Y Y Y
Y Z Y
00,00 00,00,00,00;
254
Y Y Y
Y Y Y
Y Y Z
00,00,00,00,00,00;
255
Y Y Y
Y Y Y
Y Y Y
In the above table, the Y and Z color values for the neighborhood cells are shown in the right hand columns. The corresponding binary address represented by a particular color combination of the permitter cells P 0-7 is shown in the middle column denoted ADR. In other words, each of the 256 possible color combinations for the perimeter cells P 0-7 generates a binary addresses into the neighborhood lookup table 18 . For each color combination or address, the neighborhood table outputs a string ID for up to six different surface strings as shown in the left column (as describe below, there are 58 different surface strings). The ordering of the surface strings in each entry of the above table is significant. As explained below, the surface strings are linked together into a string sequence; by ordering the surface strings as shown in each entry of the above table, the linking process is simplified.
A surface string defines the general slope of a color border passing through a given neighborhood of cells. It is possible that six different color borders will pass through a single neighborhood of cells which is why the neighborhood lookup table 18 outputs up to six different surface strings for any given neighborhood 16 . FIG. 3 shows the 58 different surface strings provided in the present invention which, as far as is known to the applicant, define every possible permutation of a color border in a raster image. The 58 surface strings shown in FIG. 3 were generated through an exhaustive, heuristic search that required many man hours to complete; the set of surface strings in FIG. 3 is a significant aspect of the present invention.
The cell coloring in each surface string shown in FIG. 3 denotes the above-described color value (Y or Z) for each cell. The black cells represent the color Y, the white cells represent the color Z, and the shaded cells represent the color X which means the color of the cell is ignored (i.e., the cell color could be either Y or Z). Referring again to the above neighborhood lookup table, the entry corresponding to neighborhood address 69 is:
SURFACE
STRINGS
ADR
P 0 P 1 P 2
P 3 T P 4
P 5 P 6 P 7
36,07,46,35,00,00;
69
Z Y Z
Z Y Z
Y Z Y
The color code for the first surface string of the above entry, surface string 36 , is shown in FIG. 3 to be:
Z Y X | Z Y X | Y X X.
Note that the color code for surface string 36 matches the color code of the neighborhood address 69 except for the don't care color X. A similar color code which matches the color code of neighborhood 69 can be verified for each of the other surface strings ( 7 , 46 and 35 ) in the above entry.
Each surface string shown in FIG. 3 has associated with it a receive slope and a send slope which define the general slope of a color border as it enters the neighborhood and the general slope as it exits the neighborhood. In the present invention, there are eight possible slope values that can be assigned to the send and receive slope of a surface string. These slope values ( 1 - 8 ) are illustrated in FIG. 4 B. Notice that there are two slope values assigned to each slope direction: diagonal, vertical, and horizontal, e.g., the slope values 1 and 2 are assigned to the diagonal direction downward from left to right. The reason two slope values are assigned to each direction is because each color border is either an east or west border.
The concept of east and west color borders is understood from the raster image comprising a simple feature as shown in FIG. 5 A. This raster image comprises only two colors, black and white. The feature depicted in the image has associated with it a west 20 A and an east 20 B white color border, and a west 22 A and an east 22 B black color border. The west white border corresponding to the east white border 20 A is the left edge of the image in FIG. 5A, and the east white border corresponding to the west white border 20 B is the right edge of the image in FIG. 5 A. Notice that in FIG. 5A the west and east borders begin in pairs, which is always the case in the present invention. West and east borders also always end in pairs, although the borders do not always end with the respective border that it began with. As described in greater detail below, the present invention generates surface strings for both the west and east borders, but the tags for generating vectors are placed only on either of the west or east borders. Both west and east strings sequences are used to place the tags, but the tags are placed only on either the west or east borders.
Referring again to the surface strings shown in FIG. 3, the receive and send slope of each surface string is assigned one of the values shown in FIG. 4 B. Consider, for example, the eleventh surface string [ 11 ]. This surface string is assigned a receive slope of 2 and a send slope of 7 . Similarly, the surface string [ 17 ] is assigned a receive slope of 8 and a send slope of 1 . As explained in greater detail below, the receive and send slopes are used to connect the surface strings into a string sequence which represents a color border in the image. The first surface string [ 1 ] is assigned a receive slope of 0 because string sequences start with this surface string. Similarly, the surface string [ 8 ] is assigned a send slope of 0 because string sequences end with this surface string. A lookup table showing each of the 58 surface strings and their corresponding receive and send slopes is shown below:
Surface Strings Table
S
R
S
t
c
n
r
v
d
g
-
-
-
S
S
I
l
l
P 0 P 1 P 2
P 3 T P 4
P 5 P 6 P 7
D
p
p
Z Z Z
Z Y Z
Z Z Y
01
0
1
Z Z Z
Z Y Z
X X Y
02
0
2
Z Z Z
Z Y Z
Z Y X
03
0
3
Z Z Z
Z Y Z
X Y Z
04
0
4
Z Z Z
Z Y Z
Y X X
05
0
5
Z Z Z
Z Y Z
Y Z Z
06
0
6
X X X
X Y X
Y Z Y
07
0
6
Y Z Y
X Y X
X X X
08
2
0
Z Z Z
Z Y Y
Z Z Y
09
9
1
Z Z Z
Z Y Y
Z Z Z
10
9
8
Y Z Z
X Y Y
X X X
11
2
7
Z Z Z
Z Y Y
Y X X
12
9
5
X X X
X Y Y
Y Z Z
13
10
6
Z Z Z
Y Y Z
Z Z Z
14
7
10
Z Z Z
Z Y Y
Z Y X
15
9
3
Z Z Z
Y Y Z
X X Y
16
7
2
X X X
Y Y X
Z Z Y
17
8
1
Z Z Z
Y Y Z
X Y Z
18
7
4
Y Z Z
Y Y Z
Z Z Z
19
2
10
Z Z Y
Z Y Z
Z Z Z
20
5
0
X X Y
Z Y Z
Z Z Z
21
6
0
Z Z Y
Z Y X
Z Z Y
22
5
1
X X Y
X Y Z
X X Y
23
6
2
Z Z Y
Z Y X
Z Y X
24
5
3
X X Y
X Y Z
X Y Z
25
6
4
Y Z Y
X Y X
X X X
26
5
0
X X Y
Y Y Z
Z Z Z
27
6
10
Z Z Y
Z Y Y
Z Z Z
28
5
8
Y X X
Z Y Y
Z Z Z
29
1
8
Z Z Y
Y Y X
X X X
30
5
9
Y Z Z
X Y Z
Y Z Z
31
2
6
Z Y X
Z Y Z
Z Z Z
32
3
0
X Y Z
Y Y Z
Z Z Z
33
4
10
Z Y X
Z Y X
Z Z Y
34
3
1
X Y Z
X Y Z
X X Y
35
4
2
Z Y X
Z Y X
Y X X
36
3
5
X Y Z
X Y Z
Y Z Z
37
4
6
Z Y X
Z Y Y
Z Z Z
38
3
8
Y X X
Z Y X
Y X X
39
1
5
Y Z Z
X Y Z
X Y Z
40
2
4
Z Z Z
Y Y Z
Y Z Z
41
7
6
Y X X
Z Y Z
Z Z Z
42
1
0
Y Z Z
Z Y Z
Z Z Z
43
2
0
Y X X
Z Y X
Z Y X
44
1
3
Y Z Z
X Y Z
X X Y
45
2
2
X X X
X Y X
Y Z Y
46 0
1
Y X X
Z Y X
Z Z Y
47
1
1
X X Y
X Y Z
Y Z Z
48
6
6
Y Z X
Y Z Z
Y Y Y
49
4
7
Y Y Y
Z Z Y
X Z Y
50
8
3
X Z Y
Z Z Y
Y Y Y
51
3
9
X Y Z
Z Y Z
Z Z Z
52
4
0
Z Z Y
Z Y X
Y X X
5
5
Z Z Z
Y Y Y
X X X
7
7
Y Y Y
Y Z Z
Y Z X
55
10
4
X X X
Y Y Y
Z Z Z
56
8
8
X Y Z
X Y Z
X Y Z
4
4
Z Y X
Z Y X
Z Y X
58
3
3
In the above table, the left columns represent the color code for each surface string shown in FIG. 3, the middle column is a string ID, and the right columns are the respective receive and send slopes assigned to each surface string. Note that in the above surface strings table there are entries which comprise slopes of 9 and 10 . These slopes correspond to the horizontal slopes of 7 and 8 shown in FIG. 4B, only the direction of the slopes are reversed for sequencing surface strings from east to west as described below.
Referring again to FIG. 2, each of the surface string IDs 24 output by the neighborhood lookup table 18 are used as an address into the surface strings table 26 shown above. Notice that surface strings 49 , 50 , 51 and 55 in the above table are special cases; they are not output by the neighborhood lookup table 18 but instead are generated by combining adjacent surface strings according to the following table:
Special Case Surface Strings Table
Special Case
Surface Strings
Strings
Combination
49
35,11
50
17,44
51
36,30
55
13,25
In the above table, the special case surface strings are generated when the string sequencer 30 of FIG. 2 encounters two adjacent surface strings which make up a special case surface string. An example of when a special case surface string is generated is described below with reference to FIG. 5 A.
The surface strings table 26 outputs the receive and send slope 28 for each surface string ID 24 output by the neighborhood lookup table 18 . The string sequence 30 then uses the pixel location 32 of the current target pixel, the surface string IDs 24 , and the surface string slopes 28 to generate string sequences 34 which define the color borders of the raster image. A string sequence 34 comprises a sequence of connected surface string IDs 24 in an order that follows the contour of the color border. An example of a string sequence 34 is shown in FIG. 2 as comprising the following sequence of surface string IDs: 44 -> 34 -> 44 -> 39 . Note that from the above surface strings table and the slopes shown in FIG. 4B, the receive and send slopes of the surface strings in this sequence match. For example, the send slope of string [ 44 ] is 3 , and the receive slope of string [ 34 ] is 3 . Referring again to the above neighborhood lookup table, the surface strings in each entry are listed in a particular order such that when the string sequencer 30 processes the surface strings at a given pixel, the surface strings are automatically linked into to the appropriate string sequences without having to check that the send and receive slopes match. Ultimately, the string sequences 34 are processed by a vector generator 36 which places tags on one of the west or east borders which are then used to generate the vectors that make up the vector image 4 .
The operation of the string sequencer 30 is understood with reference to FIG. 5A which shows a black and white raster image comprising a simple black feature and the corresponding string sequences that are generated by the present invention. As described above, the neighborhood scanner 8 of FIG. 2 scans a 3×3 neighborhood of cells 10 a through the image starting with the first pixel 12 . Thus, for the first pixel 12 no surface strings are generated by the neighborhood lookup table 18 because the color code for the neighborhood of cells 10 a (YYY YYY YYY) corresponds to address 255 in the above neighborhood lookup table, which has no surface strings for that entry. In fact, a surface string is not generated until the neighborhood of cells reaches pixel 38 where the color code for the neighborhood of cells 10 b is (YYY YYY YZZ) corresponding to address 252 in the above neighborhood lookup table which comprises only surface string [ 13 ] in that entry. That surface string [ 13 ] is the correct and only surface string for this neighborhood 10 b can be verified by examining the colors of the neighborhood 10 b in FIG. 5A with the colors of surface string [ 13 ] shown in FIG. 3 .
As described above, the surface string [ 13 ] indexes the surface strings table 26 of FIG. 2 which outputs the corresponding receive and send slopes of 10 and 6 . The string sequencer 30 processes the location of the pixel 32 , the surface string ID[ 13 ] 24 , and the receive and send slopes 28 in order to sequence the east white border 20 A in FIG. 5 A. As explained in greater detail below, there are specific priorities that establish where to begin and end a string sequence. In FIG. 5A, the east white border 20 A starts with pixel 40 based on these priorities, and sequences around the black feature resulting in a string sequence of:
17 -> 56 -> 56 -> 56 -> 13 -> . . . -> 51 .
The last surface string in the above sequence (surface string [ 51 ]) is a “corner” surface string which ends the current string sequence. A string sequence is generated for the black west border 22 A starting at pixel 42 and sequencing around the black feature resulting in a string sequence of:
18 -> 54 -> 54 -> 54 -> 12 -> . . . -> 10 .
The above string sequence 22 A ends at pixel 41 because surface string [ 10 ] is a “protruding corner” surface string which has priority over the “corner” surface string at pixel 43 . The surface string priorities are described in greater detail below. When the neighborhood 10 c reaches target pixel 42 , it begins a string sequence for both the west black border 22 A and the east black border 22 B. Thus, the resulting string sequence for the east black border 22 B is:
18 -> 33 -> 56 -> 56 -> . . . -> 10 .
Similarly, when the neighborhood of cells reaches target pixel 44 , the string sequencer 30 begins the string sequence for the west white border 20 B and generates the simple string sequence of 44 -> 36 .
How the string sequencer 30 of FIG. 2 determines which pixel to begin and end a string sequence is also a significant aspect of the present invention. Basically, the string sequencer 30 operates according to a set of priority rules which are shown in the following table:
Priority Rules
Surface String
Priority
North over South
Highest
Protruding Corner
Second Highest
Corner
Third Highest
Step
Fourth Highest
West over East
Lowest
What the above priority rules mean is that a string sequence will always begin with the surface string representing the most northern pixel and sequence from north to south. If two surface strings represent pixels at the same latitude, then the surface string's type determines the priority. In the above table, “protruding corner” surface strings, which in FIG. 3 are surface strings [ 9 ], [ 10 ], [ 14 ], [ 19 ], [ 28 ], and [ 41 ], have the next highest priority. Next in priority are “corner” surface strings which in FIG. 3 are surface strings [ 15 ], [ 18 ], [ 33 ], and [ 38 ], followed by “step” corner strings which in FIG. 3 are surface strings [ 13 ], [ 17 ], [ 27 ], and [ 29 ]. The special case surface strings [ 49 ], [ 50 ], [ 51 ] and [ 55 ] discussed above are also all corner surface strings. Finally, the lowest priority is to start string sequences with surface strings representing western pixels over eastern pixels. In other words, if two surface strings of the same type represent pixels at the same latitude, then the western surface string has priority over the eastern surface string and the sequencing will progress from west to east.
These priority rules can be understood with reference to FIG. 5 A. In evaluating the surface strings of the east white border 20 A, the string sequencer 30 of FIG. 2 will begin the string sequence with surface string [ 17 ] representing pixel 40 because it is the most northern surface string, and because it is a corner surface string which has priority over the step surface string [ 13 ] representing pixel 38 . Surface string [ 17 ] at pixel 40 is considered a corner surface string because it is adjacent to surface string [ 44 ] and the combination of [ 17 ] and [ 44 ] results in the special case surface string [ 50 ] according to the above table (again, the special case surface strings are all corner surface strings).
Thus, when the string sequencer 30 encounters pixel 38 , it begins to build a string sequence starting with the step surface string [ 13 ] and sequencing from west to east. However, when the string sequencer 30 encounters pixel 40 , the string sequence is reversed so that it begins with surface string [ 17 ] and sequences from east to west. The string sequence for the east white border 20 A continues sequencing around the black feature as shown in FIG. 5A until it reaches surface string [ 30 ]. Surface string [ 30 ] ends the string sequence because when combined with surface string [ 36 ] of the west white border 20 B it forms the special case surface string [ 51 ] which is a corner surface string. Similarly, the string sequence for the west black border 22 A begins with surface string [ 18 ] at pixel 42 because it is a corner surface string which has priority over step surface string [ 12 ]. The string sequence 22 A ends at pixel 41 because surface string [ 10 ] is a protruding corner surface string which has priority over the corner surface string [ 33 ] at pixel 43 .
In the preferred embodiment of the present invention as implemented in the computer source code attached hereto as Appendix A, the string sequencer 30 generates string sequences for both the east and west borders for each feature in the image. However, it has been determined that the vectors can be generated by placing tags only on one of the east or west borders. Both the west and east string sequences are used to place the tags, but the tags are placed only on one of the west or east borders. The 33 surface strings identified by an * in FIG. 3 are surface strings that can be part of a string sequence representing a west border. Notice that some surface strings, such as the corner surface strings [ 15 ] and [ 18 ], can be part of a string sequence representing either a west or an east border.
A better understanding of how the present invention uses the above priority rules to sequence strings is understood with reference to FIG. 5B which shows a raster image having more complex features and more colors than that of FIG. 5 A. In FIG. 5B, only the string sequences representing the west borders are shown; the string sequences for the east borders in FIG. 5B are generated, but for clarity they are not shown. FIG. 5B also illustrates the situation where the neighborhood lookup table 18 of FIG. 2 will output multiple surface strings for a single neighborhood.
Consider, for example, the neighborhood 46 near the center of the image which has the following color pattern:
Referring to the above neighborhood lookup table, this color pattern corresponds to entry:
SURFACE
STRINGS
ADR
P 0 P 1 P 2
P 3 T P 4
P 5 P 6 P 7
05,02,00,00,00,00;
7
Z Z Z
Z Y Z
Y Y Y
Thus, this entry outputs two surface string IDs [ 05 ] and [ 02 ]. The surface string [ 05 ] begins the string sequence 48 for the west border of the pyramid, and the surface string [ 02 ] begins the string sequence (not shown) for the east border of the pyramid.
The string sequence 50 begins with surface string [ 46 ] at pixel 52 because it is the most northern pixel, and sequences to surface string [ 38 ] which is a corner surface string and thus ends the sequence. Similarly, string sequence 54 begins with surface string [ 3 ] at pixel 56 because it is the most northern pixel, and sequences to surface string [ 36 ] which, when combined with surface string [ 30 ], forms special surface string [ 51 ] which is a corner surface string and thus ends the sequence.
String sequence 58 of FIG. 5B begins with surface string [ 13 ] at pixel 63 and sequences west to east as shown. The reason string sequence 58 begins with step surface string [ 13 ] at pixel 63 is because it has priority over the step surface string [ 17 ] at pixel 60 (pixel 63 is more western). The string sequence 64 starting at pixel 66 begins with surface string [ 41 ] because it is a protruding corner surface string which has priority over the corner surface string [ 15 ] at pixel 68 . Thus, surface string 64 sequences from east to west as shown and ends at protruding corner surface string [ 10 ] at pixel 70 .
String sequence 72 begins with corner surface string [ 15 ] at pixel 76 because it has priority over corner surface string [ 18 ] at pixel 74 (i.e., it is the more western corner surface string). Similarly, string sequence 78 starts with surface string [ 13 ] at pixel 65 because together with surface string [ 25 ] at pixel 69 it forms a special case corner surface string [ 55 ] which has priority over step surface string [ 17 ] at pixel 67 . It should be apparent how the remainder of the string sequences in FIG. 5B are generated using the priorities rules listed in the table above.
Contrast Tie Breaker
A necessary step in vectorizing a color image is to identify and resolve contrast ties in the image features. A contrast tie occurs when two features overlap such that one feature should appear in the background and the other in the foreground. This phenomenon is illustrated in FIG. 6A which shows a bit map of a raster image with two overlapping diagonal lines. The two possible representations of the diagonal lines in vector format are shown in FIGS. 6B and 6C; however, a human's perception of FIG. 6A will favor the representation shown in FIG. 6C over FIG. 6 B. If the contrast iii ties are not resolved “correctly”, the image will appear distorted when reconstructed from the vector data.
The contrast breaker 3 of FIG. 2 comprises two components: a contrast tie detector (CTD) for detecting the occurrence of a contrast tie in the raster data, and a contrast tie breaker (CTB) for breaking the contrast ties in a manner that parallels human perception. The general idea is to identify the presence of a contrast tie, and then to resolve or break the tie by changing the color value of a perimeter pixel relative to the target pixel in order to interrupt the string sequence of a recessive image feature, thereby allowing a dominant image feature to appear in the foreground.
In order to reduce the number of comparison permutations, both the CTD and the CTB operate on quadrant subsections of a 3×3 array of pixels as shown in FIG. 7 A. In the preferred embodiment, the contrast tie breaker 3 operates concurrently with the neighborhood scanner 8 described above. For each 3×3 array of pixels processed, the CTD performs a set of comparisons on the pixel data in the four quadrant subsections shown in FIG. 7A. A contrast tie is detected when the color of the A pixel equals the color of the D pixel (A==D), the color of the B pixel equals the color of the C pixel (B==C), and the color of the A pixel does not equal the color of the B pixel (A!=B). The raster bit map shown in FIG. 6A demonstrates when a contrast tie is detected in each of the four quadrants of the 3×3 array of pixels, as is further illustrated in FIGS. 8A-8D.
In order to break a contrast tie, the CTB performs several progressive tests over the pixel data. These tests are performed over additional pixels surrounding the 3×3 array of pixels as illustrated in FIG. 7 B. The first test, referred to as the contrast test, performs the following comparisons on the colors of the pixels
contrast 1 = (A!=E)+(A!=F)+(D!=K)+(D!=L),
contrast 2 =(B!=G)+(B!=H)+(C!=I)+(C!=J),
A_loses=contrast 1 >contrast 2 .
If A_loses is true, then the color identifier for the D pixel is set to Z. That is, the color identifier of the D pixel is set different from the target pixel (the A pixel) so that the string sequence will terminate rather than sequence through the A and D pixels. This provides the desired effect of placing a recessive image feature in the background by breaking the feature into two string sequences as illustrated by the diagonal line sequencing from left to right in FIG. 6 C. If A_loses is false, then the color identifier of the D pixel is left unchanged. This provides the desired effect of placing the dominate image feature in the foreground by allowing the string sequence to sequence through the A and D pixels as illustrated by the diagonal line sequencing from right to left in FIG. 6 C. If A_loses is neither true nor false (i.e., if contrast 1 ==contrast 2 ), then the contrast test is indeterminate and the CTB performs a further test, referred to as the “brightness” test, to break the contrast tie.
The brightness test compares the brightness of pixel A to that of pixel B. In the preferred embodiment, each pixel comprises a red value, a green value and a blue value (RGB), and a pixel's brightness is generated by summing the RGB values. With the function get_whiteness(x) returning the sum of RGB for pixel x, the brightness test performs the following comparison
contrast 1 =get_whiteness(A),
contrast 2 =get_whiteness(B),
A_loses=contrast 1 < contrast 2 .
If A_loses is true, then the color identifier for the D pixel is set to Z, and if A_loses is false, then the color identifier for the D pixel is not modified. If the brightness of the A and D pixels are equal (contrast 1 ==contrast 2 ), then the CTB performs yet another test, referred to as the “boldness” test, to break the contrast tie.
The boldness test compares the boldness of pixel A to that of pixel B, where a pixel's boldness is defined as its largest RGB value. With the function get_boldness(x) returning the largest RGB value for pixel x, the boldness test performs the following comparison
contrast 1 =get_boldness(A),
contrast 2 =get_boldness(B),
A_loses=contrast 1 < contrast 2 .
If A_loses is true, then the color identifier for the D pixel is set to Z, and if A_loses is false, then the color identifier for the D pixel is not modified. If the boldness of the A and D pixels are equal (contrast 1 ==contrast 2 ), then the CTB performs a second boldness test by comparing the second largest RGB values of the A and B pixels.
With the function get_ 2 nd_boldness(x) returning the second largest RGB value for pixel x, the second boldness test performs the following comparisons
contrast 1 =get_ 2 nd_boldness(A),
contrast 2 =get_ 2 nd_boldness(B),
A_loses=contrast 1 < contrast 2 .
If A_loses is true, then the color identifier for the D pixel is set to Z, and if A_loses is false, then the color identifier for the D pixel is not modified. If the second boldness of the A and D pixels is equal (contrast 1 ==contrast 2 ), then the contrast tie is not broken and the color identifier for the D pixel is left unmodified.
The above CTB tests are further understood with reference to FIGS. 8A-8D which correspond to the raster bit map of FIG. 6 A. Referring to FIG. 8A, the CTD detects a contrast tie in quadrant one because the color of pixels A and D are equal, the color of pixels B and C are equal, and the color of pixel A is different from the color of pixel B. Turning to the tests performed by the CTB, the contrast test is indeterminate because contrast 1 ==contrast 2 . The brightness test will indicate that pixel A is brighter than pixel B, therefore the color identifier for pixel D is not modified (it remains Y) so that the string sequence will sequence through the A and D pixels. Referring to FIG. 8B, the CTD will again detect a contrast tie in quadrant two and again the first test performed by the CTB, the contrast test, will be indeterminate because contrast 1 == contrast 2 . However, in this case the brightness test will indicate that pixel A is not brighter than pixel B so the color identifier for pixel D will be set to Z (i.e., different from pixel A). Consequently, the string sequence will terminate at pixel D and begin again at pixel A so that the diagonal line sequencing from left to right in FIG. 6C will appear in the background.
The above description of the contrast tie breaker was initially disclosed in the parent application Ser. No. 09/104,302 filed on Jun. 24, 1998. The above implementation will resolve a contrast tie correctly for a majority of cases encountered, however, the applicants have since discovered improvements to the contrast tie breaker that is capable of resolving contrast ties in additional, less frequent cases, and even cases which exceed human perception. This enhanced version basically expands the number of pixels evaluated with respect to the target pixel in a neighborhood of pixels.
First, the number of pixels evaluated in the above contrast test with respect to FIG. 7B is expanded to include the corner pixels M, N, O, and P of the 4×4 quadrants as shown in FIG. 7 C. The comparisons on the colors of the pixels then becomes
contrast 1 =(A!=E)+(A!=F)+(A!=I)+(A!=O)+(A!=H)+(D!=K)+(D!=L)+(D!=J)+(D!=N)+(D!=G),
contrast 2 =(B!=G)+(B!=H)+(B!=K)+(B!=P)+(B!=F)+(C!=I)+(C!=J)+(C!=M)+(C!=L)+(C!=E),
A_loses=contrast 1 >contrast 2 .
As described above, if A_loses is true, then the color identifier for the D pixel is set to Z. That is, the color identifier of the D pixel is set different from the target pixel (the A pixel) so that the string sequence will terminate rather than sequence through the A and D pixels. If A_loses is false, then the color identifier of the D pixel is left unchanged. If A_loses is neither true nor false (i.e., if contrast 1 ==contrast 2 ), then the contrast test is indeterminate and the CTB performs an additional test, referred to as the “area contrast” test, before performing the above described brightness and boldness tests.
The area contrast test further expands the number of pixels evaluated by increasing the 4×4 array of pixels to a 5×5 array of pixels as shown in FIG. 7 D. The color value of the pixels are then evaluated using the following comparisons
contrast 1 =(A!=P)+(A!=M)+(A!=Q)+(A!=R)+(A!=S)+(A!=T)+(A!=U)+(A!=V)+(A!=W)+(A!=X)+(A!=Y),
contrast 2 =(B!=O)+(B!=N)+(B!=Q)+(B!=R)+(B!=S)+(B!=T)+(B!=U)+(B!=V)+(B!=W)+(B!=X)+(B!=Y),
A_loses=contrast 1 >contrast 2 .
Again, if A_loses is true, then the color identifier for the D pixel is set to Z. That is, the color identifier of the D pixel is set different from the target pixel (the A pixel) so that the string sequence will terminate rather than sequence through the A and D pixels. If A_loses is false, then the color identifier of the D pixel is left unchanged. If A_loses is neither true nor false (i.e., if contrast 1 ==contrast 2 ), then the contrast test is indeterminate and the CTB performs the additional brightness and boldness tests described above to break the contrast tie.
Preferred Embodiments
Referring now to FIG. 9, shown is an embodiment of the present invention wherein the raster-to-vector (R/V) converter is implemented as a computer program 82 executed by a data processor 80 running under a particular operating system (O/S) 84 . A non-volatile memory, such as a disc drive 86 , stores the operating system 84 and the R/V converter 82 when the computer system is powered down. When the computer system is powered up, the O/S 84 and R/V converter 82 are loaded into a system memory (RAM) 88 , and the data processor 80 reads and executes the O/S 84 and R/V converter 82 from the system memory 88 . The raster image to be converted into a vector image may be stored on the disc drive 86 , or it may alternatively be loaded in real time from some other external device such as a scanner. An end user may interface with the computer system through a keyboard 90 and mouse 92 in order to direct which raster images are to be converted, and to display the vector images on a video display 94 . The source code attached hereto as Appendix A illustrates the composition of the computer program embodiment of the present invention. The source code in Appendix A is written in a programming language referred to as C, but other programming languages, such as Assembly, Pascal or Basic, could easily be employed to implement the various aspects of the present invention.
An alternative embodiment of the present invention is shown in FIG. 10 . In this embodiment, the raster-to-vector converter is implemented as part of an image processing integrated circuit. Some of the components shown in FIG. 2 are shown in FIG. 10 as combinatorial logic circuits and lookup tables implemented in transistor circuitry. It is within the ability of those skilled in the art to convert the source code shown in Appendix A into equivalent logic circuits for incorporation into an image processing integrated circuit.
The objects of the invention have been fully realized through the embodiments disclosed herein. Those skilled in the art will appreciate that the aspects of the invention can be achieved through various other embodiments without departing from the essential function. The particular embodiments disclosed are illustrative and not meant to limit the scope of the invention as appropriately construed by the following claims.
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A method and apparatus is disclosed for converting raster images into a vector format by identifying and converting the borders of image features into a mathematical format referred to as string sequences. To enable the string sequencing of color images, the present invention identifies and resolves contrast conflicts in the image features in order to avoid misperceiving the vectorized image when converted back into a raster format. A contrast conflict occurs when there is a “contrast tie” between overlapping features of the image. The feature that would normally be perceived as the dominant feature breaks the contrast tie so that when the vector image is reconstructed, the dominate feature appears in the foreground of the image while the recessive feature appears in the background. A contrast tie detector (CTD) performs a set of comparisons on the raw pixel data to detect the occurrence of a contrast tie, and a contrast tie breaker (CTB) performs another set of comparisons on the raw pixel data to break the contrast tie. A contrast tie is broken by modifying a color identifier of a perimeter pixel relative to the color identifier of a target pixel, thereby enabling the correct string sequencing of color borders.
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FIELD OF THE INVENTION
The invention relates generally to a direct steam injection apparatus for gas and liquid contact, and more particularly to a direct steam injection apparatus having an integrated reactor and boiler for starch liquefaction.
DESCRIPTION OF RELATED ART
U.S. Pat. No. 3,197,337, issued to N. F. Schink, teaches a starch heater apparatus that includes a diffusing steam distributor and a T-tube design for heating viscuous process liquid by directly mixing the liquid with steam. The steam is introduced to the device from a remote location.
U.S. Pat. No. 3,424,613, issued to K. J. Huber, et al., teaches an apparatus for the continuous production of starch pastes. It outlines an apparatus having a reaction tube downstream from a steam injection heater wherein a process slurry continues to be affected by heating while heat loss is retarded by insulation. The '613 apparatus teaches a component approach to process system integration, using a long pipe path and remote heating sources.
BACKGROUND OF THE INVENTION
During the process of preparing ethanol from starches, such as those found in corn grain, the carbohydrates comprising the starches must undergo a number of process stages so as to prepare a saccharide, such as glucose, for final fermentation. These stages include “extraction,” “cooking,” “conversion,” and “sterilization,” followed by cooling and fermentation. The extraction, cooking, conversion, and sterilization stages can be efficiently accomplished on a continuous basis using a steam injection device known as a “jet cooker” for the “cooking” stage. The “jet cooker” was adopted from the paper pulp processing industry.
Approximately 150 psi of steam is necessary for starch cooking. Steam boilers capable of producing the 150 psi of steam are expensive, heavy, and dangerous. Proper operation of these steam boilers often requires advanced knowledge or certification of proper construction, operation, and installation procedures. Further, given the high amount of pressure necessary for cooking, including for jet cooking, the technique of continuous jet cooking for small or portable fermentation process installations has been unavailable. Accordingly, the benefits of continuous direct stream injection cookers has been solely the privilege of large processing plants where the cookers have capacities characterized by pipe diameters of larger than two-and-one-half inches. There is a need for a jet cooker apparatus that is available for small or portable fermentation process installations, and, particularly, to have a jet cooker apparatus available for smaller, remote processors working in a scale as small as one-and-one-fourth inch pipe diameters.
Further, prior art steam heaters for transporting and converting vegetable starch do not teach an integrated system containing the three necessary components for jet cooking, i.e., an injector, a reactor, and a boiler. Rather, the prior art apparatuses use a non-integrated boiler to generate the steam to be injected into a process tube, that acts as a reactor in which the process fluid cooks. There is a need for a heater that is an integrated system of the three necessary components so as to accommodate small-scale processes.
SUMMARY OF THE INVENTION
Embodiments of the present direct steam injection heater apparatus provide a low cost, portable, safe, simple, and more efficient, integrated solution to heating a viscuous liquid slurry.
The direct steam injection heater accomplishes heat transfer to a process fluid traveling through the heater in the heater's process tube. The heat transfer is accomplished by two methods. First, the process fluid is heated upon contact with steam that is directly injected into the process fluid. Upon injection, the steam mixes with the process fluid. Second, the process fluid is heated by heat conducted through the process tube from the exterior of the process tube, which is affected by the condensation of steam and the liberated heat absorbed by the process material within the process tube.
During the heating steps, the process tube acts as a heated reaction tube. In one embodiment, the process tube contains a static mixer insert. In a particular configuration of this embodiment, the static mixer insert is composed of static banks of trapezoidal mixing elements.
In other embodiments, the process fluid may also be heated by multiple external heating methods, such as by use of an electric tape heater, direct firing, oil bath submersion, or radiation, to name a few.
Embodiments of the present direct steam injection heater also extend retention time of the process fluid in the externally and internally heated process tube. By externally heating the process tube and extending retention time, a lower steam temperature is required than would be required to achieve the same heating effect by direct steam injection heating in an unheated process tube of an extended heat exchanger. Extending the retention time further reduces the thermal degradation of delicate process material in the process fluid, which is a risk when process fluid travels from high temperatures in a mixing zone to the cooler temperatures of an unheated process tube. Further, heating the process tube reduces the unwanted gelling often associated with an unheated process tube.
Embodiments of the present direct steam injection heater also integrate the three components of jet cooking, i.e., the injector, reactor, and boiler, by enclosing the process tube in a high pressure steam boiler tank. The boiler tank encases the process tube, which functions as the reactor, and the injector, thus integrating the three components of the jet cooker. By wrapping the boiler around the process tube, the external surface of the process tube and the injection mechanism are exposed to condensing steam. This configuration reduces the need for potentially-dangerous, expensive, and complicated connecting plumbing that would accompany live steam and condensate trapping, as well as eliminating the need for turbine pumping.
The purpose of the foregoing Summary is to enable the public, and especially the scientists, 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 Summary is neither intended to define the invention of the application, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
Still other features and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description describing preferred embodiments of the invention, simply by way of illustration of the best mode contemplated by carrying out my invention. As will be realized, the invention is capable of modification in various obvious respects all without departing from the invention. Accordingly, the drawings and description of the preferred embodiments are to be regarded as illustrative in nature, and not as restrictive in nature.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a right-side elevation view of a direct steam injection heater with integrated reactor and boiler according to an embodiment of the invention.
FIG. 2 is a right-side elevation view of a component of the direct steam injection heater with integrated reactor and boiler according to the embodiment in FIG. 1 .
DESCRIPTION OF THE PREFERRED EMBODIMENTS
While the invention is susceptible of various modifications and alternative constructions, certain illustrated embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific form disclosed, but, on the contrary, the invention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined in the claims.
As shown in the figures for purposes of illustration, the apparatus is embodied in a novel direct steam injection heater with integrated reactor and boiler that allows for smaller-scale process use in a safe, simple, portable, and efficient integrated system.
In the following description and in the figures, like elements are identified with like reference numerals. The use of “or” indicates a non-exclusive alternative without limitation unless otherwise noted. The use of “including” means “including, but not limited to,” unless otherwise noted.
An embodiment of a direct steam injection heater with integrated reactor and boiler 20 is shown in FIGS. 1 and 2 . The heater 20 comprises two coaxial tubes of a process tube 8 and a pressure vessel 9 , preferably positioned longitudinally horizontal so that heating liquid condensate 17 contained within the pressure vessel 9 are able to collect within the pressure vessel 9 . It is preferred that the process tube 8 be of the minimum wall thickness necessary to adequately resist collapse due to external steam pressure acting upon it while minimizing the conductive heat path through the tubing wall. Further, the process tube 8 should be of a minimum diameter to allow adequate transportation of process mass flow while accommodating the expansion of steam injected into process liquid with consideration given to the displacement of a direct steam injector assembly 22 , located partially within the process tube 8 . Still further, the process tube 8 should be of a length necessary to adequately retain the process fluid for a period of time for continuous heat absorption and mixing, during which the process tube 8 acts as an absorbing heat exchanger. Still further, the process tube 8 should be composed of a material strong enough to accommodate the heat and force of pressurized steam, with properties resistant to corrosion and softening from steam and the contained process fluid, thermal conduction properties adequate to transfer heat of condensing steam through the material to the process fluid, thermal expansion properties adequate to withstand temperature differentials between the process fluid and high pressure steam, and capable of being formed and joined to additional material into an assembly of adequate strength to contain high steam pressure. Accordingly, it is preferred that the process tube 8 be constructed from welded stainless steel.
The process tube 8 has a process fluid inlet 5 , through which process fluid to be heated and mixed enters the process tube 8 , and a process fluid outlet 19 , through which process fluid that has been heated and mixed exits the process tube 8 . In the embodiment shown in FIG. 1 , a static mixing element 18 is enclosed within the process tube 8 .
The process tube 8 is surrounded by the pressure vessel 9 , which is sealed upon the process tube 8 thereby creating an envelope 24 between the process tube 8 and the pressure vessel 9 . The envelope 24 acts as both a steam heating jacket and a steam boiler. External heat sources 13 are concentrated on the exterior of the pressure vessel 19 .
It is preferred that the pressure vessel 9 be constructed of a similar material to the material used to construct the process tube 8 and be welded to the process tube at the extreme ends of the pressure vessel so as to form a seal capable of withstanding the resulting high pressure in the envelope 24 between the pressure vessel 9 and the process tube 8 . The diameter of the pressure vessel 9 should be minimized to minimize the wall thickness necessary for containing the high pressure steam contained within the envelope 24 but of a diameter large enough to create an envelope of adequate configuration and volume to accommodate the accumulation of sufficient heating liquid condensate 17 within the pressure vessel 9 so as to allow the pressure vessel 9 to act as a boiler tank.
Attached to the pressure vessel 9 are a first external connection fitting 3 , a second external connection fitting 7 , and a third external connection fitting 11 . The first external connection fitting 3 is located at the highest point of the pressure vessel 9 and is configured to allow venting, sensing, and measurement of live steam. It is preferred that the first external connection fitting 3 is configured to be of a size adequate for venting steam at a rate appropriate for the applied heat input. In some embodiments, the first external connection fitting 3 may be configured to allow attachment of a suitable pressure relief device (not shown).
The second external connection fitting 7 and the third external connection fitting 11 are configured to accommodate the function of an external water level control unit (not shown). Further, the second external connection fitting 7 is configured to allow for sensing of the level of the heating fluid condensate 17 , and the third external connection fitting 11 is configured to allow for sensing of the steam pressure.
The embodiment of the direct steam injection heater with integrated reactor and boiler, as shown in FIGS. 1 and 2 , also includes a direct steam injector assembly 22 , comprising a vertically-arranged injector tube 4 that passes vertically from the interior of the process tube 8 , through the envelope 24 , through the pressure vessel 9 , to the exterior of the pressure vessel.
The injector tube 4 defines a port 2 located in the section of the injector tube 4 that is between the process tube 8 and the pressure vessel 9 . The port 2 is configured to accommodate the flow of steam through port 2 into the injector tube 4 .
A steam flow rate throttle 1 is attached to the injector tube 4 at a section of the injector tube 4 located exterior to the pressure vessel 9 . The steam flow rate throttle 1 is configured to accommodate adjustment of a throttling interference element 12 , which is configured to accommodate control of the flow of steam through port 2 into the injector tube 4 . A seal 16 is located inside the injector tube 4 , between the steam flow rate throttle 1 and the throttling interference element 12 . The seal 16 is configured to discourage leakage of steam to the exterior of the pressure vessel 9 .
A steam diffuser 10 is attached to the injector tube 4 at the section of the injector tube 4 located within the process tube 8 . The steam diffuser 10 is configured to accommodate passage of steam from the injector tube 4 to the interior of the process tube 8 . It is preferred that the steam diffuser 10 be configured to accommodate down-stream flow of the steam passing from the injector tube 4 into the interior of the process tube 8 .
In some embodiments the direct steam injector assembly 22 is configured so that the steam diffuser 10 is located center to the process tube 8 , so as to allow steam to radially disperse from the center of the process tube 8 .
While there is shown and described the present preferred embodiment of the invention, it is to be distinctly understood that this invention is not limited thereto but may be variously embodied to practice within the scope of the following claims. From the foregoing description, it will be apparent that various changes may be made without departing from the spirit and scope of the invention as defined by the following claims.
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Disclosed is an apparatus for heating a viscuous liquid slurry by direct steam injection in small scale installations. A process tube, through which the slurry flows, is surrounded by a pressure vessel. The pressure vessel acts as a high pressure steam boiler tank, heating the process tube. The process tube, having a length to accommodate mixing of the slurry within, act as a reaction chamber, into which steam is injected via a direct steam injection assembly. The integration of the injector, reactor, and boiler avoids the need for an external boiler and associated plumbing.
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CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. provisional application 60/538,484 filed on Jan. 20, 2004.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] This work has been funded in whole or in part by U.S. government funding. The government may have certain rights in the invention.
TECHNICAL FIELD
[0003] The present invention relates to a method and device for the gas-phase separation of peptide and protein ions (or other biological molecules) by ion mobility and for depositing them intact on a surface in a spatially addressable manner. The surface onto which the proteins are deposited can be modified for the purpose of constructing microarrays of biologically relevant materials or for promoting the growth of highly ordered protein crystals.
BACKGROUND OF THE INVENTION
[0004] Analogous to DNA-based array techniques, protein microarrays based on antibody (fragments, mimics, or phage display), aptamer, or affinity ligand arrays have been developed for (i) rapid screening of protein expression, (ii) identification of protein-protein, protein-DNA, and protein-ligand interactions, and (iii) determination of post-translational modifications. However, techniques for constructing protein arrays, such as (i) photolithography, (ii) robotic spotting, (iii) droplet printing techniques, (iv) micro-contact printing, and (v) dip-pen nanolithography often lack selectivity for structural conformations of a particular protein or for protein modifications. It should be noted that all of these techniques require analyte purification prior to deposition on the surface substrate (e.g., spatially distinct protein spots to probe protein-protein interactions). Furthermore, solution-based methods (separation based on analyte hydrophobicity, affinity, isoelectric point, etc.), which are typically used for analyte purification, are usually time consuming and are inefficient at separating protein isoforms (conformational or structural). These drawbacks are particularly salient, for example, in developing assays for protein misfolding diseases (e.g., transmissible spongiform encephalopathies, amyloidoses, and prion diseases). The present invention is a gas-phase purification method for biological molecules based on ion mobility and methods for selectively depositing material in a spatially addressable manner onto a surface.
[0005] Gas-phase ion mobility (IM) provides ion separation by generating or injecting ions in/into a gas-filled drift tube (typically 1 to 760 Torr) where they migrate under the influence of a weak electrostatic-field (typically 10 to 100 V cm −1 Torr −1 ). The theory of IM is fully developed in texts by Mason and McDaniel, (E. W. McDaniel and E. A. Mason, “The Mobility and Diffusion of Ions in Gases”, Wiley, New York, N.Y. (1973); E. A. Mason and E. W. McDaniel, “Transport Properties of Ions in Gases”, John Wiley & Sons, Inc., New York, N.Y. (1988)) and the combination of IM with mass spectrometry dates back to the early 1960's. (see Phys. Rev. Lett. 6, 110-111 (1961)). Briefly, the mobility (K) of an ion is defined as the ratio of the drift velocity (v d ) to the electric field strength (E):
K = v d E ( 1 )
[0006] When the ion-neutral collision energy approaches the thermal energy of the system, the mobility approaches the so-called “low-field” limit and can be related to the collision cross-section (Ω), or apparent surface area, of the ion:
K = 3 16 q N ( 1 μ 2 π k B T ) 1 2 1 Ω ( 2 )
[0007] Where N is the number density of the drift gas, q is the ion charge, μ is the reduced mass of the ion-neutral collision pair, k b is Boltzmann's constant, and T is the system temperature. Thus, ion mobility provides separation selectivity based on the charge-to-collision cross-section ratio of the ion in a particular drift gas, in contrast with mass spectrometry based ion separation, which separates analyte on the mass-to-charge (m/z) ratio of the ion.
[0008] The mobility-separated ions elute from the IM drift cell with near-thermal kinetic energies, which provides unique potential for deposition onto a surface. The energy regime (e.g., thermal (<1 eV), hyperthermal (1-100 eV), low-energy (0.1-10 keV), or high energy (keV-MeV)) with which the ion collides with a surface dictates the prevailing ion-surface interaction that ensues. For example, when an intact ion or molecule comes to rest on a surface, i.e., with insufficient collisional energy to break the chemical bonds of the molecule, it is hereafter termed “soft-landing.” Cooks has described the soft-landing energy regime to be in the range of typically 5-10 eV, but this is highly dependant on the identity of the ion and the surface onto which it is landed (see Rev. Sci. Instrum. 72, 3149-3179 (2001)). For example, larger molecules possess many more degrees-of-freedom (i.e., energy levels) into which collision energy can be deposited; consequently, large ions can dissipate the energy into ro-vibronic modes or transfer the energy to the surface (e.g., closely spaced alkyl chains comprising a self-assembled monolayer (SAM)). Note also that the extent of translational-to-internal energy conversion of the ion and the extent of the inelastic partitioning of energy between the ion and the surface strongly depends on the surface composition (ranging from ˜60-70% energy transfer to the surface for SAMs). Similarly, neutralization of the impinging ion also depends on the ion type and surface composition. For example, electron transfer from the surface easily neutralizes odd-electron ions, but this reaction does not apply to even-electron ions. Further, neutralization is less efficient with F-SAM than H-SAM surfaces (fluorinated and protonated SAMs) where charge-exchange is more efficient with a hydrocarbon rather than fluorinated surface (reflected in the higher ionization potential of fluoroalkanes) ( Int. J. Mass Spectrom. Ion Proc. 122, 181-217 (1992)). To afford the soft-landing of ions, prior art has consisted of selecting the ions to be landed by mass spectrometric methods. In contrast, soft-landing after ion mobility selection can be achieved without the need for elaborate deceleration lenses which are sometimes necessary to lower the collisional energy of the ion with the target surface.
[0009] In the late 1970's, Cooks and colleagues first demonstrated soft-landing of mass-to-charge selected CS −+ , CS 2 −+ , and CS 2 2+ ions with various metal targets for surface modification ( Int. J. Mass Spectrom. Ion Phys. 23, 29-35 (1977)). These researchers showed that impinging a CS 2 −+ beam onto a lead target at kinetic energies of 10 eV yielded sulfide species of more covalent character than those obtained using 1 keV ions (as indicated by a shift to higher binding energies as determined by X-ray photoelectron spectroscopy (XPS)). This indicated that surface chemical reaction with molecular ions was possible at low collision energies, whereas at 1 keV reactions were dominated by those of atomic species (i.e., the molecule likely dissociates into constituent atomic neutrals/ions prior to reaction with surface species). Subsequently, Rabalais and colleagues demonstrated the generation of metal carbides and the diamond allotrope of carbon (i.e., sp 3 hybridized carbon films) by impinging a mass-to-charge selected hyperthermal (20-200 eV) beam of C −+ onto several different metal surfaces (i.e., Si(100), Ni(111), Ta, W, and Au) (Science 239, 623-625 (1988)). In a related report, these researchers investigated the interaction of mass-to-charge selected low kinetic energy beams (3-300 eV) of C −+ , O −+ , and CO −+ with a Ni(111) surface ( J. Chem. Phys. 88, 5882-5893 (1988)). It was found that CO −+ preferentially dissociated above a collisional kinetic energy of ca. 9 eV, whereas at lower energies the yield of intact (i.e., soft-landed) CO was significantly enhanced (determined by XPS and Auger electron spectroscopy). It was later demonstrated that larger polyatomic ions, such as silyl ethers (e.g., (CH 3 ) 3 SiOSi(CH 3 ) 2 + , 35 ClCH 2 (CH 3 ) 2 SiOSi(CH 3 ) 2 + , and 37 ClCH 2 (CH 3 ) 2 SiOSi(CH 3 ) 2 + ), could be mass selected and soft-landed at low collisional kinetic energies (5 to 10 eV) on F-SAM surfaces (see Science 275, 1447-1450 (1997); Int. J. Mass Spectrom. Ion Proc. 174, 193-217 (1998)). The F-SAM surface provided two primary benefits: (i) energy dissipation via the C 10 fluoroalkane chains, and (ii) a proposed entanglement of soft landed molecules within the framework of the F-SAM assembly (particularly for sterically bulky species). The utility of H-SAM surfaces (C 12 ) were also examined, which provide “softer” surfaces onto which ions can be landed in that the conversion of translational to internal energy of the ion is reduced in comparison with an F-SAM, ˜13% vs. 20-30% for an H-SAM and an F-SAM, respectively ( Int. J. Mass Spectrom. 182/183, 423-435 (1999) and references therein).
[0010] The soft-landing of biologically relevant molecules by using low-energy mass selected ions was recently described by Smith and coworkers. They used Fourier transform ion cyclotron resonance to mass-select and soft-land a 160 base pair double-stranded oligonucteotide onto a nitrocellulose membrane ( J. Am. Chem. Soc. 121, 8961-8962 (1999)). Cooks and colleagues have more recently demonstrated selective soft-landing and subsequent bioactivity measurements of several proteins (cytochrome c, lysozyme, apomyoglobin, insulin, and trypsin) representing a complex mixture. In this work, a linear ion trap mass spectrometer was used where an estimated 80% soft landing efficiency (from trapped ions to plate deposition) was achieved with 2 mm spatial resolution (see (1) B. Gologan, Z. Takats, T. Blake, Z. Ouyang, V. J. Davisson, and R. G. Cooks, Self-Assembled Monolayers as Substrates for Laser Desorption: Analysis of Soft-Landed Proteins, presented at the 51st American Society for Mass Spectrometry Conference, Montreal, Canada, June 2003; (2) Z. Takats, Z. Ouyang, B. Gologan, T. Blake, A. J. Guymon, V. J. Davisson, and R. G. Cooks, Protein Microarrays by Ion Soft-Landing, presented at the 51st American Society for Mass Spectrometry Conference, Montreal, Canada, June 2003; and (3) T. A. Blake, Z. Ouyang, A. J. Guymon, S. Kothari, Z. Takats, B. Gologan, and R. G. Cooks, A Microarray Fabrication System Using Ion Soft-Landing from a Linear Ion Trap Mass Analyzer, presented at the 51st American Society for Mass Spectrometry Conference, Montreal, Canada, June 2003).
BRIEF SUMMARY OF THE INVENTION
[0011] In the present invention, there is an apparatus for detecting and selectively depositing gas-phase ions onto a surface, comprising: an ion source for generating ions; means for separating the generated ions, said means for separating being fluidly coupled to said ion source; means for selectively gating said ions based on their mobilities and means for directing said ions to a substrate, said means for selectively gating and said means for directing being fluidly coupled to said ion mobility drift cell; and, an ion detector fluidly coupled to said ion mobility drift cell. In some embodiments, the ion source is selected from the group consisting of atmospheric pressure MALDI, infrared MALDI, LDI, electrospray, nanospray, photoionization, multiphoton ionization, resonance ionization, thermal ionization, surface ionization, electric field ionization, chemical ionization, atmospheric pressure chemical ionization, radioactive ionization, discharge ionization, and any combination thereof. In some embodiments, the means for separating comprises an ion mobility cell or a mass spectrometer or both. In some embodiments, the means for separating comprises an ion mobility cell. In some embodiments, the ion mobility cell applies electric fields selected from the group consisting of uniform electrostatic fields, periodic-focusing electrostatic fields, and any combinations thereof. In some embodiments, the ions are further separated by unreactive and/or reactive collisions with species selected from the group consisting of helium, neon, argon, krypton, xenon, nitrogen, oxygen, methane, carbon dioxide, water, methanol, methyl fluoride, deuterated analogs thereof, tritiated analogs thereof, and any combination thereof. In some embodiments, the means for selectively gating ions based on their mobilities and directing them to a solid substrate comprises directing ions by a technique selected from the group consisting of direction by an electrostatic-field, direction by a magnetic-field, and a combination of direction by an electrostatic-field and direction by a magnetic-field. In some embodiments, the means for selectively gating and said means for directing are the same. In some embodiments, the means comprises an electrostatic steering plate. In some embodiments, the apparatus gates and directs ions to a solid or condensed-phase surface at energies of 0 to 10 eV. In some embodiments, the apparatus gates and directs ions to a solid or condensed-phase surface at energies of 10 to 100 eV. In some embodiments, the apparatus gates and directs ions to a solid or condensed-phase surface at energies of 100 to 1000 eV. In some embodiments, the apparatus gates and directs ions to spatially distinct regions of a surface comprising a material selected from the group consisting of steel, gold, glass, self-assembled monolayer(s), nitrocellulose, condensed-phase substrates, chemically functional moieties, chemically reactive moieties, biologically active species, and combinations, patterns and layers thereof. In some embodiments, the apparatus further comprises an RF cooling apparatus. In some embodiments, the apparatus further comprises deceleration optics upstream of said substrate. In some embodiments, there is an apparatus for detecting and selectively depositing gas-phase ions onto a surface, the apparatus comprising an ion source for generating ions, a two dimensional ion mobility spectrometer fluidly coupled to said ion source, means for directing said ions to a substrate, said means for directing being fluidly coupled to said ion mobility drift cell.
[0012] In another aspect of the present invention, there is a method for analyzing and selectively depositing gas phase ions comprising: generating ions from an ion source; separating said ions; detecting said ions; and, selectively gating and directing said ions onto a substrate. In some embodiments, the said step of selectively gating and directing comprises depositing said ions onto a substrate in a spatially addressable manner by patterning ions onto a solid substrate, patterning ions onto a condensed-phase substrate, or a combination of patterning ions onto a solid substrate and patterning ions onto a condensed-phase substrate. In some embodiments, the ions to be patterned comprise ions of species selected from the group consisting of amino acids, polyamino acids, nucleotides, polynucleotides, antibodies, antibody antigens, carbohydrates, polycarbohydrates, biomolecules, ligands, mimics, aptamers, derivatives thereof, assemblies thereof, complexes thereof, and any combination thereof. In some embodiments, the ions comprise proteins or peptides or both. In some embodiments, the ions comprise small molecules interacting with proteins or peptides or both proteins and peptides. In some embodiments, the step of directing promotes the growth of ordered crystals. In some embodiments, the ions to be patterned comprise ions with a molecular weight less than 100000 amu. In some embodiments, the ions to be patterned comprise ions with a molecular weight less than 10000 amu. In some embodiments, the ions to be patterned comprise ions with a molecular weight less than 1000 amu. In some embodiments, the ions to be patterned comprise atoms/molecules with a molecular weight less than 500 amu. In some embodiments, the ions to be patterned comprise ions with a molecular weight greater than 100000 amu.
[0013] The present invention differs from the prior art in that ion selectivity is accomplished on the basis of charge-to-collision cross-section rather than mass-to-charge. Ion selectivity based on ion mobility separation provides several important advantages over prior art solution-based purification or gas-based mass-to-charge selection of biological molecules: (i) in many cases isobaric and isoform species (e.g., structural and/or conformational isomers) can be separated, (ii) the separation mechanism does not rely on solution-phase physical properties (e.g., affinity, hydrophobicity, isoelectric point, etc.), (iii) ion mobility is amenable to a wide variety of molecular classes or complex mixtures thereof (e.g., proteins, lipids, oligonucleotides, carbohydrates, etc.), and (iv) in many cases it is sensitive and selective for post-translationally modified peptides (or proteins).
[0014] The present invention is directed towards devices and methods for the ionization, gas-phase separation/purification, and subsequent spatially addressable deposition/collection of biomolecules. This differs from the prior art in that it uses ion mobility as a means to separate gas-phase ions on the basis of their apparent charge-to-surface area ratio (e.g., collision cross-section with a neutral drift gas) rather than mass-to-charge. In an exemplary embodiment of the present invention, biomolecular ions are generated by matrix assisted laser desorption/ionization (MALDI), whereby the analyte is co-crystallized with ultraviolet (UV) absorbing molecules (typically organic acids). The analyte and matrix is subsequently irradiated with UV photons to ultimately produce biomolecular ions. It should be noted that with minor modification to the present apparatus, other ion sources can be used, for example: atmospheric pressure MALDI, infrared MALDI, LDI, electrospray, nanospray, photoionization, multiphoton ionization, resonance ionization, thermal ionization, surface ionization, electric field ionization, chemical ionization, atmospheric pressure chemical ionization, radioactive ionization, discharge ionization, and combinations thereof.
[0015] The gas-phase ions can either be generated at the entrance plane of the ion mobility cell, or subsequently injected into the mobility cell for separation. The ions migrate under the influence of a uniform or periodic-focusing electrostatic field, whereby their translational motion is impeded by collisions with neutral drift gas molecules (e.g., He, N 2 , Ar, H 2 O, etc.). Note that by using a reactive drift gas, the ion mobility cell can also be used to modify the original ion through the promotion of gas-phase ion chemistry (charge-exchange, H/D exchange, solvation, etc.) for subsequent deposition. In the exemplary embodiment, ions exit the mobility drift cell with near-thermal kinetic energy. The ions are then accelerated to a low kinetic energy (1-10 eV) above the thermal temperature of the system and electrostatic lenses collimate and focus the ion beam. The ion beam then passes between two electrostatic steering plates whereby the temporal voltage state of the two plates determines the ultimate position where the selected ions will be deposited. For example, in the exemplary embodiment, ions are selected on the basis of their arrival time distribution in the region between the two steering plates. The state of the steering plates is switched to direct the selected ions to a collection surface and then switched (in a bracketed manner about the arrival time distribution of the selected ions) to direct non-selected ions towards an ion detector. The latter is performed to continuously monitor the arrival time distribution of the ensemble of ions generated by the ionization event.
[0016] The exemplary embodiment of the present invention, as described herein, provides for biomolecule ionization, gas-phase separation on the basis of ion mobility, ion selection, and spatially addressable ion collection/detection. A device (apparatus) has been constructed, according to the exemplary embodiment described herein, and utilized for the selective deposition of intact peptides. Modifications to the exemplary embodiment described herein are envisioned including the utilization of alternate ionization sources (described above), ion selection (optimization of ion optical geometries), ion collection (utilization of different energy regimes and surface modification(s)), and ion detection (mass spectrometry, fluorescence, condensation counting by Fraunhofer diffraction, etc.) strategies.
[0017] The foregoing has outlined rather broadly the features of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
[0019] FIG. 1 is a (A) Schematic diagram of an exemplary embodiment of the present invention providing for ion mobility separation, ion optic selection, and subsequent soft-landing of ions, incorporating a multichannel plate ion detector. (B) Schematic diagram of an embodiment of the invention utilizing ion mobility separation, ion optic selection, and subsequent soft-landing of ions incorporating ion fluorescence detection;
[0020] FIG. 2 is a Simulation of the ion trajectories of the invention allowing: (A) protein ion detection, (B) collection of undesired components of initial mixture, and (C) collection of the purified protein. Simulations were performed for 10 eV lysozyme (Hen egg white, M.W.=16,238 Da.) ions;
[0021] FIG. 3 is a (A) Diagram of the timing of two ion mobility detection/protein collection cycles utilizing a 75% duty cycle. (B) Schematic diagram of the relative steering plate voltages (V ESP ) for each stage of the detection/separation scheme in (A);
[0022] FIG. 4 is a Schematic diagram of the alternating fast-switch circuitry used to electrostatically direct ions to either the detection or collection plane.
[0023] FIG. 5 . is a Arrival time distribution plots illustrating the selectivity achievable with the switching circuitry. Plots illustrate (top) complete beam-to-detector deflection, and decreasing the deflected pulse from 150 to 20 μs around the peak centered at 225 μs
[0024] FIG. 6 . A MALDI-time-of-flight-MS spectrum of gramicidin s recovered from the collection surface after ion mobility-soft-landing deposition
DETAILED DESCRIPTION OF THE INVENTION
[0025] As used herein, “a” or “an” means one or more. The plural encompasses the singular and the singular encompasses the plural.
[0026] The invention includes an instrument and method for detecting and selectively depositing gas-phase ions onto a surface. The instrument comprises an ion source for generating ions, means for separating the generated ions wherein the means for separating is fluidly coupled to said ion source; means for selectively gating said ions based on their mobilities and means for directing said ions to a substrate, said means for selectively gating and said means for directing being fluidly coupled to said ion mobility drift cell; and, an ion detector fluidly coupled to said ion mobility drift cell.
[0027] FIG. 1A provides a schematic diagram of a device representing an exemplary embodiment of the present invention, instrument 1 , is comprised of five major components: an ion mobility chamber 2 , a source of ions 3 (such as peptide and proteins), a system of ion lenses for focusing and beam positioning 4 , a detector for determining ion mobility distributions 5 , and a surface for means of collecting peptide or protein ions 6 . Briefly, a solid matrix/protein sample is deposited on a probe 7 and subsequently introduced into the ion mobility chamber via a vacuum interlock 8 . Ultraviolet photons from a laser 9 directed at the probe tip 10 then preferentially generates intact gas-phase protonated molecular ions which are directed towards a differential aperture plate 11 by means of applying a nearly-linear electric field between 11 and the ion mobility backing plate 12 . A neural drift gas supplied to the ion mobility chamber via a metered port 13 impedes the progress of ions through the electric field. Provided a suitable ratio of the electric field to the neutral gas number density is used, ions are nearly linearly separated based on their apparent charge-to-collision-cross section ratio.
[0028] The separated peptide and protein ions then pass through the differential aperture plate 11 (200 to 1000 μm diameter) and are collimated and focused by a system of ion lens elements 4 . In an exemplary embodiment of the present invention, the separated ions are then directed by electrostatic steering plates 14 to one of three final positions: an ion detector 15 (see also FIG. 2A ), a contaminant collection probe 16 (see also FIG. 2B ), or a peptide/protein collection surface 6 (see also FIG. 2C ). When the separated ions are directed to the ion detector ( FIG. 2A ), the ion mobility distribution of all of the separated ions is recorded. Neutral atoms or molecules that pass through the aperture plate are not electrostatically steered from their straight trajectory and are collected on the contaminant collection probe or are pumped from the detector/collector cell 17 . Based on the arrival time distribution of the ions that is recorded at the detector, a timing sequence for the voltages applied to the electrostatic steering plates for the selection of a particular peptide or protein for deposition is generated.
[0029] In the present invention, the ion source can be any ion source known in the art. Preferably, the ion source comprises by any ionization instrumentation, including but not limited, to atmospheric pressure matrix-assisted laser desorption ionization (MALDI), infrared MALDI, laser desorption ionization (LDI), electrospray ionization, nanospray ionization, photoionization, multiphoton ionization, resonance ionization, thermal ionization, surface ionization, electric field ionization, chemical ionization, atmospheric pressure chemical ionization, radioactive ionization, discharge ionization, and combinations thereof. Employing the ionization instrumentation on a sample generates ions. The sample can be any sample, but is preferably a chemical or biochemical sample. Means for separating ions can be accomplished by any means known in the art, but is preferably performed on the basis of the ions' gas-phase mobility (ion mobility). Preferably, when using ion mobility, the separating means comprises applying electric fields to the ions, and preferably, the electric fields are is selected from the group consisting of uniform electrostatic fields, periodic-focusing electrostatic fields, and combinations thereof. Other fields, known to those of skill in the art, are also useful in the present invention. Separation of ions on the basis of their gas-phase mobility is also accomplished by reactive or unreactive collisions with species selected from the group consisting of helium, neon, argon, krypton, xenon, nitrogen, oxygen, methane, carbon dioxide, water, methanol, methyl fluoride, deuterated analogs thereof, tritiated analogs thereof, and any combinations thereof. Means for selectively gating ions of particular mobility and means for directing ions to a solid substrate may be of any type know in the art, including those selected from the group consisting of direction by an electrostatic-field, direction by a magnetic-field, and combinations thereof. Means for gating and deflecting are preferably performed using electrostatic or magnetic fields, however, mechanical means may be used. Means for gating and directing are preferably performed by using electrostatic steering plates, however, other techniques well known in the art may be used, and these include direction by the application of magnetic fields also. Mechanical means for gating through the use of shutters is also possible.
[0030] The instrument and method of the present invention, in addition to its ability to selectively gate and direct analyte ions onto a substrate, can also incorporate a number of recent advances in ion mobility/mass spectrometry. For example, in U.S. Pat. No. 6,6,639,213 to Gillig et al, an improved ion mobility instrument using periodic focusing electric fields that minimize the spatial spread of the migrating ions by keeping them in a tight radius about the axis of travel is described. U.S. Pat. No. 6,6,639,213 is incorporated by reference as though fully described herein. In U.S. application Ser. No. 09/798,030 (published as U.S. Patent Application Publication 2001/0032929 A1 on Oct. 25, 2001), Fuhrer et al, disclosed an improved ion mobility instrument using combinations of periodic and hyperbolic focusing electric fields. U.S. Patent Application Publication 2001/0032929 A1 is incorporated by reference as though fully described herein. In U.S. Pat. No. 6,683,299 to Fuhrer et al, time-of-flight mass spectrometer instruments for monitoring fast processes using an interleaved timing scheme and a position sensitive detector are described. U.S. Pat. No. 6,683,299 is incorporated by reference as though fully described herein. In U.S. application Ser. No. 10/689,173 (published as U.S. Patent Application Publication 2004/0113064 A1 on Jun. 17, 2004), of Fuhrer et al, the time-of-flight mass spectrometer instruments for monitoring fast processes using an interleaved timing scheme and a position sensitive detector was supplemented with an additional fragmentation step for additional analytical information. U.S. Patent Application Publication 2004/0113064 A1 is incorporated by reference as though fully described herein. In pending U.S. application Ser. No. 10/967,715, Fuhrer et al described improvements in the fast time-of-flight instrument, including photo-fragmentation of ions, the use of multiple pixel ion detectors positioned within the mass spectrometer, and the generation and analysis of one or more spatially distinct ion beamlets. It is understood that a time of flight mass spectrometer can be used as a detector stage in place of detector 5 . In pending U.S. application Ser. No. 10/969,643, Schultz et al describe improved ion mobility focusing through the use of alternating high and low electric field regions. U.S. application Ser. No. 10/969,643 is incorporated by reference as though fully described herein.
[0031] A representative timing diagram for the voltage applied to the electrostatic steering plates is illustrated in FIG. 3 for two cycles of ion mobility detection and peptide/protein deposition. In this example, all of the ions from the initial MALDI event are directed to the detector to determine the arrival time distribution of the ion mobility separated ions ( FIG. 3A (ii)). Based on the elution time of the peptide or protein to be deposited which was determined in (ii), ions eluting at that time are then directed to the collection surface 6 for the remaining ionization events in that cycle ( FIG. 3A (iii)). For elution times not corresponding to either detection or collection, no net steering is used so that undesired ions (e.g., from contaminants or matrix related ions), and neutrals are collected on a contaminant collection probe. Owing to the plane of symmetry between the collection probe and detector, the voltage applied to the electrostatic steering plates is the same in magnitude, but opposite in polarity, depending on the desired ultimate trajectory of the ions (i.e., detector or collector, FIG. 3B ). By changing the magnitude of the voltage applied, the spatial position of the ion deposition can be tuned. It should be understood that the dimensions of the deflections and the distances between the detector 5 , collector 6, and contaminant collection probe 16 can be very small (miniaturized).
[0032] In the present exemplary embodiment, steering plate voltage polarity is determined by the electronic state of fast-switching circuitry ( FIG. 4 ). The state of the switch is changed by the application of a tunable waveform (±5 V) constructed on the basis of the timing diagram as illustrated in FIG. 3 . When the inverted (−) or non-inverted (+) output state is “high” the switch delivers a voltage equal to that supplied by an external power supply (±0 to 35 V) to the inverted or non-inverted electrostatic steering plate, respectively. Concurrently, the inverted or non-inverted output in the “low” state is connected to ground. The current circuitry has a rise/fall time of ca. 1 ns and can operate up to a switching frequency of approximately 100 kHz. Arrival time distribution selectivity (i.e., mobility separated ion selectivity) by using the switching circuitry described is illustrated in FIG. 5 . The top panel illustrates the arrival time distribution observed by gating all mobility-separated ions (atomic ions ablated from the steel probe tip, matrix related ions (α-cyano hydroxycinnamic acid), and the peptide gramicidin s) to the detector. In subsequent panels, the steering plates are gated to transmit ions from the peak eluting at 220 μs, but in successively more selective timing windows ranging from 150 to 20 μs. Note that owing to the symmetry of the instrument, the selected ions in FIG. 5 are directed to the surface by simply switching the electronic state of the switching circuitry. In terms of selectivity, there is little to no evidence for ions reaching the detector from rejected portions of the arrival time distribution.
[0033] An instrument was built based upon the exemplary embodiment of the present invention for proof-of-concept experiments. The peptide gramicidin s ([PVOLF] 2 ) was soft-landed (7.5 eV kinetic energy) onto a hydrocarbon coated-stainless steel collection surface for 15 hours at a MALDI repetition rate of 30 Hz. The deposited peptide was then washed into 10 μL of deionized water, spotted onto a MALDI sample plate with a co-matrix of 2,5-dihydroxybenzoic acid, and then analyzed by MALDI-time-of-flight-MS resulting in the spectrum illustrated in FIG. 6 . This spectrum clearly indicates that gramicidin s is deposited on the collection surface intact. In another embodiment, the utilization of high repetition rate MALDI (i.e., 0.5 to 10 kHz) will reduce these deposition times to several minutes.
[0034] In the present exemplary embodiment, the collection surface is positioned at a point equidistant from the steering region as that from the detector plane to said region. The collection surface may consist of a static probe, plate, or microwell plate and may be surface modified. The spatial addressability of ion deposition can be accomplished by one or more pairs of electrostatic steering plates (or other ion optical geometries). Manipulation of the direction of ion deposition can be used to pattern the deposition. In an alternate embodiment, the ion beam position remains static and the collection surface is translated relative to the ion beam via x-y micropositioners for spatial addressability. The ultimate spatial resolution of deposited peptides or proteins on the collection surface, in the present exemplary embodiment, is limited by the diameter of the differential aperture plate 12 (ca. 200 μm), but could be conservatively improved to 10 to 100 μm 2 spot sizes by utilizing ion optical methods well known in the art.
[0035] In alternate embodiments of the present invention ( FIG. 1B ), on-line analysis of the amount of analyte deposited will be accomplished by in situ analysis of the native-state fluorescence of the gas-phase ions by means of using a pulsed-laser source of UV photons for excitation 18 (e.g., 266 nm by using a frequency-quadrupled Nd:YAG laser) and measuring emission by means of an avalanche photodiode or photomultiplier tube detector 19 situated 90° with respect to the fluorescence laser propagation. In the presently-described exemplary embodiment, the focused beam of ions passes through a fluorescence interaction region 20 for non-destructive detection prior to soft-landing at the collection surface 21 . Excess excitation photons and undesired ions deflected by means of the steering plates are collected at a photon/ion beam dump 22 positioned in-line with the excitation laser.
[0036] In either embodiment, the collection surface may consist of a variety of materials, for example: steel, gold, glass, H-SAM, F-SAM, glycerol, or condensed-phase materials. The collection surface can further be functionalized using alkanethiol-gold or silanization chemistries (e.g., reaction with primary amines for peptides and proteins) to immobilize and the deposited analyte. By immobilizing the analyte with covalent cross-linking agents, the deposited material can be patterned on the collection surface to generate microarrays of desired material. The present invention may alternatively be used for promoting the growth of highly ordered protein crystals from said gas-phase purified analytes. The ordering of such protein crystals may be enhanced by carefully cooling the mobility separated ions by application of RF gas phase cooling procedures and further controlling the beam energy of the thus cooled mobility separated proteins by use of carefully designed deceleration optics located in front (upstream) of the collector surface. Instrumentation and method for RF cooling are well known to those of skill in the art; see for example, U.S. Pat. No. 6,6,639,213, U.S. Patent Application Publication 2001/0032929 A1, U.S. Pat. No. 6,683,299, U.S. Patent Application Publication 2004/0113064, and U.S. application Ser. No. 10/969,643; these patents and published patent applications are incorporated by reference as though fully described herein. This crystallization may also be desirably influenced by the choice of collector surface morphology which might include, for example, an ordered single crystalline substrate. The use of a two dimensional mobility spectrometer could also be used (with or without gating techniques) for simultaneously spatially separating and depositing the entire output of the MALDI (or laser ablation) ionization process. The generation of the analyte ions is not restricted to the MALDI process. The practice of this invention would easily include the use of a pulsed or trapped output from a continuous soft ionization source. Alternatively the use of a continuous generation of the ions by, for example, electrospray ionization followed by a differential ion mobility spectrometer for selecting the desired analyte ions for deposition. One application of any of these embodiments will be to crystallize proteins or epitopes of drug binding sites of proteins so that their atomic structure can be determined by synchrotron generated X-ray diffraction techniques so that the atomic composition and geometric orientation of the drug binding site can be determined. One additional application is in drug screening which is made possible by the combination of soft ionization, mobility separation, gating and soft landing for the growth of bio-crystals which contain a small molecule drug candidate already interacting with the protein which contains the targeted binding site. The growth of these single crystal proteins or peptide which containing the small molecule can thus enable the structure determination by X-ray diffraction. This allows the direct determination of whether or not the potential drug candidate reaches the binding site and if so how it interacts with the binding site. A further application is the soft landing of semiconductor or small metal particulates so that combinatorial analysis of physical properties (e.g. chemical reactivity, electron emission, catalytic activity, photoemission of electrons) can be rapidly determined.
[0037] All patents and publications referenced herein are hereby incorporated by reference. It will be understood that certain of the above-described structures, functions, and operations of the above-described embodiments are not necessary to practice the present invention and are included in the description simply for completeness of an exemplary embodiment or embodiments. In addition, it will be understood that specific structures, functions, and operations set forth in the above-described referenced patents and publications can be practiced in conjunction with the present invention, but they are not essential to its practice. It is therefore to be understood that the invention may be practiced otherwise than as specifically described without actually departing from the spirit and scope of the present invention as defined by the appended claims.
REFERENCES
[0000]
U.S. Pat. No. 4,822,466 J. W. Rabalais and S. R. Kasi, Chemically Bonded Diamond Films and Method for Producing Same (Apr. 18, 1989).
U.S. Pat. No. 5,374,318 J. W. Rabalais and S. R. Kasi, Process for the Deposition of Diamond Films Using Low Energy, Mass-Selected Ion Beam Deposition (Dec. 20, 1994).
#20010032930 K. J. Gillig and D. H. Russell, Periodic Field Focusing Ion Mobility Spectrometer (Application filed Feb. 28, 2001).
#20010032929 K. Fuhrer, K. J. Gillig, M. Gonin, D. H. Russell, J. A. Schultz, Mobility Spectrometer (Application filed Feb. 28, 2001)
Foreign Patent Documents
[0000]
#JP2002069622 K. Koji, N. Atsushi, S. Takeshi, Soft-Landing Method for Cluster Ion Species (Aug. 3, 2002).
#WO 99/38194 C. M. Whitehouse, B. A. Andrien Jr., Mass Spectrometry from Surfaces (Jul. 29, 1999).
Literature and Presentations
[0000]
[1]. E. W. McDaniel and E. A. Mason, The Mobility and Diffusion of Ions in Gases , Wiley, New York, N.Y. (1973).
[2]. E. A. Mason and E. W. McDaniel, Transport Properties of Ions in Gases , John Wiley & Sons, Inc., New York, N.Y. (1988).
[3]. W. S. Barnes, D. W. Martin, and E. W. McDaniel, Mass Spectrographic Identification of the Ion Observed in Hydrogen Mobility Experiments, Phys. Rev. Lett. 6, 110-111 (1961).
[4]. V. Grill, J. Shen, C. Evans, and R. G. Cooks, Collisions of Ions with Surfaces at Chemically Relevant Energies: Instrumentation and Phenomena, Rev. Sci. Instrum. 72, 3149-3179 (2001).
[5]. M. R. Morris, D. E. Riederer Jr., B. E. Winger, R. G. Cooks, T. Ast, and C. E. D. Chidsey, Ion/Surface Collisions at Functionalized Self-Assembled Monolayer Surfaces, Int. J. Mass Spectrom. Ion Proc. 122, 181-217 (1992).
[6]. V. Franchetti, B. H. Solka, W. E. Baitinger, J. W. Amy, and R. G. Cooks, Soft Landing of Ions as a Means of Surface Modification, Int. J. Mass Spectrom. Ion Phys. 23, 29-35 (1977).
[7]. J. W. Rabalais and S. Kasi, Growth of Thin Chemically Bonded Diamondlike Films By Ion Beam Deposition, Science 239, 623-625 (1988).
[8]. H. Kang, S. R. Kasi, and J. W. Rabalais, Interactions of Low Energy Reactive Ions with Surfaces. I. Dose and Energy Dependence of 3-300 eV C + , O + , and CO + Reactions with a Ni(111) Surface, J. Chem. Phys. 88, 5882-5893 (1988).
[9]. S. A. Miller, H. Luo, S. J. Pachuta, and R. G. Cooks, Soft-Landing of Polyatomic Ions at Fluorinated Self-Assembled Monolayer Surfaces, Science 275, 1447-1450 (1997).
[10]. H. Luo, S. A. Miller, R. G. Cooks, and S. J. Pachuta, Soft Landing of Polyatomic Ions for Selective Modification of Fluorinated Self-Assembled Monolayer Surfaces, Int. J. Mass Spectrom. Ion Proc. 174, 193-217 (1998).
[11]. J. Shen, Y.-H. Yim, B. Feng, V. Grill, C. Evans, and R. G. Cooks, Soft Landing of Ions onto Self-Assembled Hydrocarbon and Fluorocarbon Monolayer Surfaces, Int. J. Mass Spectrom. 182/183, 423-435 (1999) and references therein.
[12]. B. Feng, D. S. Wunschel, C. D. Masselon, L. Pasa-Tolic, and R. D. Smith, Retrieval of DNA Using Soft-Landing After Mass Analysis by ESI-FTICR for Enzymatic Manipulation, J. Am. Chem. Soc. 121, 8961-8962 (1999).
[13]. B. Gologan, Z. Takats, T. Blake, Z. Ouyang, V. J. Davisson, and R. G. Cooks, Self-Assembled Monolayers as Substrates for Laser Desorption: Analysis of Soft-Landed Proteins, presented at the 51st American Society for Mass Spectrometry Conference, Montreal, Canada, June 2003.
[14]. Z. Takats, Z. Ouyang, B. Gologan, T. Blake, A. J. Guymon, V. J. Davisson, and R. G. Cooks, Protein Microarrays by Ion Soft-Landing, presented at the 51 st American Society for Mass Spectrometry Conference, Montreal, Canada, June 2003.
[0058] T. A. Blake, Z. Ouyang, A. J. Guymon, S. Kothari, Z. Takats, B. Gologan, and R. G. Cooks, A Microarray Fabrication System Using Ion Soft-Landing from a Linear Ion Trap Mass Analyzer, presented at the 51st American Society for Mass Spectrometry Conference, Montreal, Canada, June 2003.
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A method and device for the gas-phase separation of ionic biomolecules including peptide, and protein or inorganic cluster ions or nanoparticles by ion mobility and for depositing them intact on a surface in a spatially addressable manner is described. The surface onto which the proteins are deposited can be modified for the purpose of constructing microarrays of biologically relevant materials or for promoting the growth of highly ordered protein crystals.
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This invention relates to a waistband fastener, in particular for trousers, skirts or the like.
BACKGROUND OF THE INVENTION
A waistband fastener of the type which comprises a latch rail fixed to one portion of the waistband and on which latch rail a slider or carriage connected to the other portion of the waistband is guided in an adjustable and latchable manner, in such a way that a latch finger engaging between the teeth of the latch rail is provided for the slider, is known from U.S. Pat. No. 4,180,891. There, a lever hinged to the slider effects the engagement of the latch finger. The hinged lever has two arms, one of which serves as an operating grip and the other of which continues or merges into the latch finger which directly engages with the latch gaps or recesses of the latch rail. Although in that construction the disposition of the hinge axis very close to the rail is achieved, relative movements between the latch rail and the slider result due to the pivoting motion of the hinged lever. Moreover, a rather high pressure application is required. For example, if the tooth gaps are not positioned, with regard to the latch finger, in such a way that the latter can be pivoted therein, the teeth can be damaged. Furthermore, the high space requirement for the swung-out position of the hinged lever is deemed to be a disadvantage, as well as the risk of an undesired opening due to accidental contacts with the hinged lever, which risk cannot be completely excluded. Additionally, the manufacture of such a waistband fastener is relatively expensive.
BRIEF DESCRIPTION OF THE INVENTION
It is an object of the present invention to provide a waistband fastener of this kind which has a simpler construction and is both less expensive to manufacture and easier to use.
Generally speaking, due to the construction according to the present invention, a waistband fastener having an enhanced utility as well as an essentially simplified structure is achieved; thus, the slider itself is, at the same time, the operating means or handle of the fastener. The adjusting or latching takes place nearly exclusively in the longitudinal plane of the functional slider/latch rail components; transversely thereto there is practically no space requirement, since the usual hinged lever, which generally neccessitates high space volume for pivoting it, is dispensed with. Such a waistband fastener can, moreover, be constructed extremely flat, inasmuch as a deviation out of the longitudinal direction takes place, at most, to the extent of the depth of a tooth gap, i.e., approximately 1-2 mm.
Concretely, the arrangment is such that the latch finger can be brought out of engagement with and fully clear of the sawteeth of the latch rail by shifting the slider transversely to the latch rail so that the sawteeth can be completely skipped by the slider when the latter is moving along the latch rail in one direction. Therefore, the actuation required in order to enlarge the width of the waistband is limited to a simple directed exertion of pressure onto the slider, namely, transversely to the longitudinal direction of the latch rail, and a subsequent shifting of the slider.
An optimal version of the so-called push/pull system is thus achieved. Intermediate parts such as the hinged lever and its bearing means are rendered superfluous. The movement in the opposite direction, i.e., the shifting of the slider in the sense of a reduction of the width of the waistband, can be simply effected by a pulling at the slider, by means of which the sloping backs of the sawteeth are freely overrun by the latch finger. Moreover, an advantageous solution is provided by means of a spring of the slider, which spring acts upon the backside of the latch rail and serves for pressing the latch finger into the tooth gaps of the latch rail. On the one hand, this spring effects the functionally correct tooth engagement, whereas, on the other hand, the spring force can be overcome by a deliberate transverse shifting of the slider in order to bring the latch finger out of engagement with the teeth.
Another advantage is that since the sawtooth structure is arranged at the side of the fastener facing the article of clothing, the relatively intense frictional stressing of the clothes resting on it, for example, of the jacket, is eliminated, so that the covering strip which otherwise would be provided to overlie the teeth ripples and afford a protective effect in this respect, could even be omitted. Such a covering strip is provided in the above mentioned prior art citation. Therefore, the covering strip now has, at most, a function to improve the appearance of the article of clothing.
A further advantage of the present invention is due to the fact that the latch rail comprises a foot extending longitudinally in the middle region of the rail, and the two lateral portions of the latch rail which freely extend from the bottom mounting plane of the latter and comprise the sawtooth structure are overlapped or encompassed by respective U-shaped legs of the slider. As a whole, therefore, a slider with a generally C-shaped cross-sectional profile is provided, the middle part or web of which forms the bottom of the slider which continues or goes over into the C-legs in order to finally continue or go over into the C-like angular portions directed toward each other. An optimal guiding in this respect results by means of paired sets of legs of the slider which are offset or spaced from each other in the direction of movement of the slider. Appropriately, the legs are provided at the ends of the slider.
The arrangement thus is such that the latch fingers are constituted by means of prolongated ends of the legs extending beyond the lateral regions of the guiding portions. Practically, in consideration of the orientation of the sloping sawtooth backs, the latch fingers are correspondingly obliquely oriented. Furthermore, the latch rail has a groove for sewing, which groove is provided at the backside overlying the foot of the latch rail and thus reduces the material agglomeration of such a foot; the latch rail can, therefore, be sewed on more easily and, especially, also faster.
As regards the spring which urges the slider into the latching position, this is suitably constituted by a tongue of the slider bottom extending in the longitudinal direction of the slider. Such a free-cut tongue can be given the desired bias force by bending it outwardly. Another possibility resides in that the tongue is formed as a buckle spring hinged at one end. With reference to the desired intentional, i.e., defined, tilting of the slider on the latch rail, the root or bottom portion of the spring is provided in opposed position with regard to those portions of the legs which act in a merely guiding manner. The free distance between this root or bottom portion of the spring and the corresponding inner flank or side of the guiding portion can be adapted to the thickness of the lateral area of the latch rail, so that the tilting or pivoting caused by the spring is restricted to the other end of the slider where the latch finger or pair of fingers is provided.
In order to optimize the sliding conditions, it is furthermore proposed to provide, in the root or bottom portion of the spring, a convex surface which extends along the whole transverse width of the slider and is directed toward the backside of the latch rail. In contrast thereto, the free end of the spring tongue is arranged in opposite position to the latch fingers. Moreover, an advantageous implementation resides in that the width of the spring tongue is greater than the width of the sewing-on groove Of the latch rail. In this manner, a relatively large guiding width is used for the sliding of the spring tongue.
In order to attach the fastener mechanism to the article of clothing so as to be out of sight, the slider leaves open or free a passageway or tunnel for a covering strip for the latch rail. The covering strip is transversely sewed onto the waistband before the ends of the latch rail. The passageway or tunnel forms, at the same time, an advantageous guiding support for the covering strip. Furthermore, it is structurally and location-wise of advantage, in this connection, when the passageway or tunnel is formed by feet projecting rearwardly from the slider bottom, with the ends of the feet continuing or going over into angularly extending cramp-fixing legs. The beam-like feet form the corresponding spacing means and also provide a surface stiffening for the slider bottom.
A solution which is especially suitable in this connection as regards the attachment or setting-on, is provided by the feature that the sets of feet projecting at the backside of the slider, i.e., being bent in the direction of the outer waistband, form a cramp-deviation or deflection channel. Such a cramp-deviation channel renders a special abutment superfluous; the deviation-abutment is directly realized at the slider itself. An implementation which is structurally advantageous results from the fact that each deviation channel for a cramp spike is formed by a folding back of a portion or first region of the foot adjacent an insertion opening and by a folding of a free end portion or second region of the foot under the proximate edge portion of the slider bottom. In this regard, one advantageously starts with a channel length which enables a complete covering or disappearance of the tapered or pointed cramp spike. This is of advantage on optical or visual grounds as well as with regard to its usability, since no free-standing tips are present which could lead to damage of the cloth.
In order to avoid any deviational movement of the cramp spike even with large cloth thicknesses, the arrangement is, moreover, such that the folded-back portion and the folded-under portion of each foot define a guiding thickness at the inner side. This can be additionally taken into account at the punching-out of the slider, which is most suitably formed from a folded blank, by means of a corresponding stamping or deformation. The so-formed bead has, at the same time, a stiffening effect which is especially of importance for an abutment to be formed at the slider itself. Therefore, even the customary material with thin walls can be used.
In order to further enhance an easy, in particular hooking-free folding of the cramp spike, the inner vertex between the folded-back portion and the folded-under portion of each foot extends in a concave arc. It is further proposed that the free section of the cramp deviation channel tapers toward the inner end. Herewith, even the resetting spring force of the corresponding parts of the deviation channel can be used for an effective deviation loading of the cramp spike. In order to provide an input portion for the deviation channel with a cross-section as large as possible, despite this clamping force acting first in the end phase, the invention furthermore contemplates that the tapering continues, i.e., that the channel narrows, until below the corresponding thickness dimension of the cramp spike and that the channel zone lying in front of it and the insertion opening comprise a greater free cross-section of approximately two times the thickness dimension of the cramp spike.
As regards the entrance region, it can prove to be of advantage that the portion of the foot which defines the passageway or tunnel, as well as the folded-back portion, run essentially parallel to each other and that the folded-under portion is rectangularly bent inwardly. Alternatively, under maintenance of the wall profile, the arrangement can also be such that the folded-back portion runs at an acute angle with respect to the foot portion and practically touches, with its bead-free portion of the inner surface, the foot/slider bottom edge region. By means of this feature, a continuous insertion of the cramp spikes is effected already at the beginning, which cramp spikes in the end phase then move, in an advantageous embodiment, at an acute angle against the folded-under portion directed toward the slider bottom and are in hook-like manner deviated or even curled or bent round.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is described in more detail hereinafter with reference to two embodiments thereof illustrated in the drawings, in which:
FIG. 1 shows a waistband fastener, according to a first embodiment of the invention, for a pair of trousers, the fastener being illustrated in side view and in approximately natural size;
FIG. 2 a top view of the fastener but without any illustration of the curvature thereof;
FIG. 3 shows a top view of the slider in isolated representation;
FIG. 4 shows a section taken along the line IV--IV in FIG. 3;
FIG. 5 shows a section taken approximately along the line V--V in FIG. 1 and illustrates the latched position, the latch rail itself not being represented in section;
FIG. 6 shows a sectional view similar to FIG. 5 but illustrates the out-of-engagement position;
FIG. 7 shows a section taken along the line VII--VII in FIG. 5;
FIG. 8 shows the slider in isolated representation, as seen from the front end at the tunnel side;
FIG. 9 shows a modification of the slider, in perspective view;
FIG. 10 shows the associated cramp or staple, likewise in perspective view;
FIG. 11 shows a further modification of the slider containing a buckle spring, likewise in perspective view;
FIG. 12 shows a second embodiment of the waistband fastener according to the invention, the fastener being illustrated in side view, on a pair of trousers in approximately natural size;
FIG. 13 shows a top view of the slider of the fastener of FIG. 12, in isolated representation;
FIG. 14 shows a section taken along the line XIV--XIV in FIG. 13;
FIG. 15 shows a section taken along the line XV--XV in FIG. 12 and illustrates the latched position of the fastener, the latch rail itself not being represented in section;
FIG. 16 shows a section taken along the line XVI--XVI in FIG. 15;
FIG. 17 shows the slider in isolated representation as seen from the front end at the tunnel side, however with the feet forming the deviation channel for the cramp spike shown in section;
FIG. 18 shows a section taken along the line XVIII--XVIII in FIG. 15;
FIG. 19 shows the slider in perspective view;
FIG. 20 shows the associated cramp or staple, likewise in perspective view;
FIG. 21 shows a section taken along the line XXI--XXI in FIG. 17;
FIG. 22 shows a view similar to FIG. 17 but illustrates a modification of the deviation channel for the cramp spike; and
FIG. 23 shows a section taken along the line XXIII--XXIII in FIG. 22.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings in greater detail, FIGS. 1 and 2 show the waistband fastener according to one embodiment of the present invention, which is longitudinally displaceably guided along a latch rail 1, as including a slider or carriage 2. The latter is adjustably and latchably guided on the latch rail 1 which comprises a regular or uniform sawtooth structure having sawteeth 3 (see also FIG. 5). The gaps between the teeth are denoted by reference numeral 4. The movement-blocking steep tooth flanks 3' extend vertically with respect to the longitudinal direction of the rail. The tooth backs 3", in contrast thereto, are oriented at an acute angle to the longitudinal direction of the rail. The tooth tips 3"' are truncated. The ratio between the length of the steep tooth flank 3' and that of the sloping tooth back 3" is approximately 1:2.
The latch rail 1 is made of plastics material, for example, polyethylene, and has a roughly V-shaped symmetrical section, with a middle region a and two side portions b, and is dominated by a centrally running sewing-on groove 5 (FIG. 7) which is open at the side of the rail facing the slider 2. The sewing-on groove forms, in opposite direction, a foot 6. The sidewardly projecting portions b of the wing-like rail profile are joined by the longitudinal middle region a and are significantly spaced, due to the presence of the foot 6, from the mounting surface 7 of an inner waistband part A. The seam fixing the latch rail 1 to the waistband part A is denoted by the reference numeral 8.
The lateral portions b of the rail carry, on the side thereof facing the mounting surface 7, the described sawtooth structure. As viewed in the direction of orientation of the lateral portions b away from each other, i.e., cross-sectionally, the pair-wise arranged rows of sawteeth 3 cover approximately half of the length of these portions (FIG. 7). Apart from the latching function, the sawteeth 3 have the additional function of stabilizing the change-over region between the longitudinal middle portion a forming the foot 6, and the lateral portions b.
As can be seen especially clearly in FIG. 7, the slider 2 being guided along the latch rail 1 has a generally C-profile, when seen in section, which C-profile overgrips or surrounds the edge zones of the rail body in a U-like manner. The bottom 9 of the slider 2 is formed by the bridge or web portion of the C-profile and continues, at both ends of the bridge, in the form of legs 10 overlapping or covering the edges of the rail portions b. The legs 10 are rectangularly bent and go over into the form of inwardly directed guiding portions 11. The guiding portions 11 are so dimensioned, in overlapping the edge portions b, that they end at a distance from the tooth structure, i.e. the respective lines of sawteeth 3. These guiding portions 11 are also to be seen at the left side in FIGS. 5 and 6.
The guiding portions lying at the right side in FIGS. 5 and 6 continue beyond the extent of the other guiding portions so that they form, with their prolongated ends, respective latch fingers 12. The latch fingers 12, or more particularly the guiding portions forming units thereof, are obliquely oriented in adaption to the sloping tooth backs 3" and have a corresponding contour. The oblique contour is arranged at the middle region of each latch finger. In contrast thereto, the end of each latch finger 12 which faces the bottom side of the associated lateral portion b, runs in parallel to the longitudinal extent of the latch rail 1. The same applies with respect to the free end of each latch finger 12, namely, the higher end of the latch finger, which is oriented towards the plane of the underlying truncated tooth tips 3"'. The end flank 12' at the right side of each latch finger 12 coacts, in a blocking manner, with the corresponding steep tooth flank 3' of the sawteeth 3. The ends of the latch fingers 12 which are directed towards each other, terminate short of the longitudinal small sides of the foot 6 and at a clear spacing therefrom (see FIG. 7).
The slider 2 is spring-loaded (see FIGS. 3-11) in the direction of engagement of the latch fingers with the teeth 3. Its spring, which is designated 13, is arranged at the slider bottom 9. The spring 13 bears against the back side 14 of the latch rail 1 (FIGS. 5 and 6) and thereby brings the latch fingers 12 into engagement with the tooth gaps 4 at that portion, as can be seen from FIG. 5. When in this position, the slider 2, which is fixedly connected with the waistband part B overlying the waistband part A located nearer to the wearer's body, can be shifted freely in the direction of the arrow y, because the latch fingers 12 freely overrun the sawteeth in a ratchet-like manner. This movement, of course, is in the direction of a reduction of the waistband width.
If it is desired, in contrast thereto, to enlarge the waistband width, it is necessary to deliberately exert a pressure force, onto either the slider 2 or the waistband part B holding it, in the direction of the arrow P (see FIG. 6). In this way, the out-of-engagement position shown in FIG. 6 is achieved, in which the slider 2 can be moved counter to the direction of the arrow y. Such a transverse shifting of the slider 2 is possible because use is made of a free space F available in the direction P, which free space F corresponds at least to the depth of engagement, i.e., the height, of the sawteeth 3. Moreover, a free deflection space z is provided above the blunt or truncated tooth tips of the sawteeth, which space z corresponds at least to the total height of the obliquely oriented latch finger 12 With respect to the mounting surface 7.
The guiding portions 11 at the left side end of the slider 2 (FIG. 5) do not provide a corresponding free space F; rather, at that location there is provided a narrow guiding contact which is adapted to the thickness of the lateral rail portions b. There also lies the root region W of the spring 13, which spring extends in the guiding direction of the slider 2. A positive effect with respect to the sliding is provided in that the root region W of the spring 13 has a convex surface 15 extending along the total transverse width of the slider 2. The convex surface 15, which is oriented toward the back side 14 of the latch rail 1, is simply formed by impressing a transverse bead into that part of the wedge-shaped slider 2.
The sliding function and even the tilting function is furthermore enhanced by a construction of the guiding portions 11 at that location insofar as the sliding surface facing the lateral portions b is broken at both ends. The corresponding socket or holder 16 can be seen in FIG. 5.
The width of the spring 13 which, according to FIGS. 3 and 7, is formed by free-cut tabs or straps of the slider bottom 9, is so selected that the spring 13 does not penetrate into the sewing-on groove 5, but is guided at the smooth remaining width of the backside 14 of the latch rail 1. The sewing-on groove 5 extends along the latch rail foot 6 and occupies only a part of the width of the latter (see FIG. 7).
As shown in FIG. 3, the spring 13, which, as previously stated, is constituted by a longitudinally running tongue of the slider bottom 9, additionally is provided with a windowlike opening 17. By virtue of the presence of the latter, the tongue has two relatively small spring legs 13' and a transverse web 18 lying at the free end of the spring 13 which constitutes the spring head. In order to enhance its slidability, the web 18 is transversely rounded, but at least is chamfered at the rail-side transverse edges thereof.
In the modification according to FIG. 9, even a clear curling or rolling-round of the spring head 18 can be seen. Here, a central tongue is provided as the spring 13 which is laterally accompanied by a pair of curlings or loops 19 ending in the root region W of the spring 13. The lateral bent-round parts 19 in this case assume the above-described function of the root region W. Taking into account the tilting shifting of the slider 2 in this region, the guiding portions 11 are obliquely oriented, in order to afford the free movement necessary for the tilting motion. The divergence with respect to the plane of the slider bottom 9 lies in the direction of the slider end at that location.
The modification according to FIG. 11 uses a different type of spring construction, wherein a buckle spring formed of suitably bent wire is used as spring 13. The buckle spring is U-like in shape and is provided, at the root side, with axle-like transverse portions 20 which are received and positioned in bent-round parts 19 provided on the slider at that location. The axial length of the outwardly oriented axle portions 20 is such that a plug-in mounting at the inner side of the slider bottom 9, using the free space between the two bent-round parts or journals 19, is possible. The free end of the spring 13 again comprises a convex configuration in the sense of the construction of the spring head 18 of the described kind. The bias-generating offset of the spring 13 results from a bend 21 provided in the region of the spring near the anchored end of the same.
In order to generate the bias force of the spring 13 in each of the described variants thereof and to achieve the functional capability as a whole, it will be understood that sufficient free space is provided between the legs 10 or between the guiding portions 11, as the case may be.
Reverting now to FIG. 9, the slider 2 there shown is provided with a passageway or tunnel 22 in the back of the slider 2, between the slider and the waistband B carrying the same. The passageway 22 permits the insertion of a latch rail cover strip 23 (FIGS. 1 and 2) which extends over the latch rail while keeping the same hidden from view. When mounting the waistband fastener on the garment, the cover strip 23 is sewed at both ends thereof onto the waistband part A (the part which lies nearer to the wearer's body) at locations spaced from the ends of the latch rail 1. That end zone of the cover strip 23 which is not additionally covered by a trousers turn-up or cuff 24 is secured to the waistband part A by stitching 25, while the other end zone of the strip (shown to the left of the latch rail in FIG. 1) is secured in place by stitching 26.
The passageway or tunnel 22 is formed by feet 27 starting from the slider bottom 9 and projecting in the direction of the outer waistband part B. The feet 27 terminate in respective right-angle bent laterally outwardly directed sections 28 constituting a pair of cramp-anchoring legs. In essence, the latter constitute a pair of eyelet-like extensions having openings 29. The associated U-shaped cramp or staple element 30 is shown in FIG. 10 and has transversely extending legs which are tapered to form cramp tongues or spikes 31, which when inserted through the openings 29 are bent over at the back sides of the anchor legs 28. Instead of a continuous tapering of the cramp spikes or tongues 31, a tapering merely at the extremities thereof is also sufficient.
The modification according to FIG. 11 differs from that of FIG. 9 in that in FIG. 11 the feet 27 are attached to the slider at each side of the latter between the respective two colateral guiding portions 11, starting from the correspondingly cut-back legs 10. At first, the feet 27 slope downwardly in a gabled roof-like manner, after which they continue as a pair of parallel legs defining therebetween the passageway or tunnel 22. A pair of cramp spikes or tongues 31, each of which at its base has a width which is smaller than that of the respective foot 27, project from the feet, so that the resultant shoulders 32 can seat fully on the mounting surface of the waistband part B. The associated backing or counter-plate, which would lie at the outside of the waistband part B, is not shown.
The operation of the waistband fastener as so far described is, briefly summarized, as follows:
In order to reduce the waistband width, the trouser pocket cuff or turn-up (waistband part B) is simply gripped and drawn in the direction of the arrow y (FIG. 5). The latch fingers 12 thereby slide over the sawtooth structure, rising along the slanted backs 3" of the teeth and falling back again into the respective successive gaps 4 under the action of the spring 13. After the slider has been released, the latch fingers 12 remain in whatever gaps they have then reached and block any reverse movement of the slider by virtue of the end flanks 12' of the latch fingers 12 being engagement with the steep flanks 3' of the latch rail teeth 3.
If, in contrast thereto, the waistband width is to be enlarged, only a transverse shifting of the slider in the direction of the arrow P (FIG. 6), leading to a disengagement of the latch fingers from the teeth, and a subsequent longitudinal shifting movement or adjustment of the slider 2 counter to the direction of the arrow y, is required. The transverse shifting is effected against the force of the spring 13 and with a slight tilting of the slider 2 about the root region W of the spring, the same being facilitated by the convex surface 15 engaging the backside of the latch rail 1. During this tilting motion, the end flank 12' of each latch finger 12 is moved out of the then occupied gap 4 by the distance z so as to clear the steep flank 3' of the associated sawtooth 3' and the latch fingers can thus move to the right through the space above the truncated tops 3"' of the teeth 3. When the desired new position of the slider is reached, the pressure exerted thereon is relaxed and the slider 2 pivots, under the load of the spring, back into the FIG. 5 position to block further movement of the slider to the right.
The waistband fastener according to the second embodiment of the invention (FIGS. 12 to 23) has principally the same construction, as regards the latch function and the reverse movement. Like reference numerals are used in these views in the same sense as in FIGS. 1-11, albeit without unnecessary repetitions in the text. The operation direction has changed, however, as this fastener has a different, i.e. right-side, orientation of the steep tooth flanks. Thus, the refinement here resides in the different stopping function of this waistband fastener, which is a kind of stopping function that does not necessitate a special or separate deflection abutment. Such a deflection abutment is realized at the slider 2 itself.
In this respect, the arrangement is such that each of the feet 27 projecting to the back side of the slider 2, i.e., in the direction of the overlying waistband B (FIGS. 14 and 15), forms a deviation or deflection channel 33 (FIG. 17) for the associated cramp spike or tongue 31. The latter thus is no longer deviated or folded-back at the back side of the fastening legs 28. In contrast, in the embodiment according to FIGS. 12 to 23 these fastening legs 28 are made with much longer dimensions during the punching process, and these longer portions are folded back, starting from the ends of the feet 27 (and, more precisely, from the ends of the insertion openings 29), in a direction opposite to the initial orientation of the feet 27.
The folded-back first regions or portions 28 of the feet 27 are hereinafter designated as folded-back portions 34, each of which then continues into a folded-under second region or portion 35 (FIGS. 17 and 18). The folded-under portions are laterally inwardly directed, i.e., each runs transversely to the length of the latch rail I. From FIG. 17, as well as from some of the other figures, it can be clearly seen that the folded-under portions 35 are formed from the free end regions of the material tabs forming the feet 27. Each such free end region extends under a respective edge region 9' of the slider bottom. As can be furthermore gathered from FIG. 17, the inner crest or vertex between each folded-back portion 34 and its associated folded-under portion 35 runs in a concave arc 36. Each arc or bend 36 occupies substantially a third of the tab forming the peripheral portion of the associated deflection channel 33 for the cramp spike 31. The fabric-piercing cramp spikes 31 which enter via the insertion openings 29 are thereby deflected or deviated in the directions of the lateral edges of the rail 1 in a hooking manner, without, however, freely protruding there. On the contrary, the cramp spikes 31 remain covered in the gap-like deviation channels 33.
As can be furthermore seen from FIG. 17, in this modification the portions of the feet 27 which define the passageway or tunnel 22 and the folded-back regions or portions 34 which are located outwardly of the feet essentially run parallel to each other, with the folded-under regions or portions 35 being oriented at right angles to the portions 34 and the feet 27. On the other hand, the modification according to FIG. 22 provides a profile contour in which the folded-back regions or portions 34 run at opposite acute angles with respect to the feet 27. The angle of inclination in each case is approximately 30°. The respective inclined positions and the somewhat greater lengths of the folded-back portions 34 lead to the result that the respective concave arcs or bends 36, which here are somewhat more narrow, are situated behind, but slightly laterally inwardly of, the corner edges 37 between the slider bottom 9 and the feet 27. Due to the essentially right-angle bending of the folded-under portions 35 relative to the folded-back portions 34 also in this case, the portions 35 consequently extend obliquely, at likewise acute angles, toward the slider bottom 9.
In both variants, a continuously running guiding bead 38 is provided at the inner side of each foldedback portion 34 and folded-under portion 35 and the intermediate concave inner crest or vertex of the arc or bend 36. Its groove structure, which is realized by a simple wall displacement, can clearly be seen from FIGS. 21 and 23. The guiding bead 38 is adapted to the maximum width of the flat, symmetrically tapered cramp spike or tongue 31 (FIG. 20) and extends in the plane of symmetry of the feet 27 at both sides of a raised material zone which forms the non-beaded portion of the inner surface and approximately corresponds to half of the guiding bead width. The guiding bead 38 stabilizes that portion of the slider 2 which forms the abutment for the cramp deviation. A pair of beads 39 extends also in the same transverse direction and stiffen that region of the slider bottom 9 which is at the fastening side. A corresponding structural arrangement is also found in the modification according to FIG. 4.
In the modification according to FIG. 17, each cramp spike 31 at first, following the respective insertion direction, enters linearly into the starting portion of the associated deviation or deflection channel 33. According to the modification of FIG. 22, however, the hook-forming deflection or deviation of each cramp spike 31 takes place practically already at the beginning, immediately after moving through the respective frontal insertion opening 29. Here, the free end of each cramp spike 31 is forced through a respective narrowing region V which is located approximately in the middle region of the associated deviation channel 33 and is defined by means of the acute-angled orientation of the folded-back portion 34 and the proximity of the non-beaded portion of the inner surface of the portion 34 to the corner edge 37 between the slider bottom 9 and the associated foot 27.
In contrast thereto, the modification according to FIG. 17 provides a corresponding narrowing V at the inner end of each cramp spike deviation channel 33. Here too, the narrowing V goes to a width less than the corresponding thickness dimension of the cramp spikes 31. The preceding channel zone of each deviation channel 33 and the associated window-like, elongated rectangular insert opening 29, however, occupy a free section which is significantly greater than the free height of the inner end of the deviation channel 33. By Way of example, the channel width, measured in the thickness direction, corresponds approximately to two times the thickness dimension of the cramp spikes 31.
In all cases, after the application or insertion of each as before U-shaped cramp or staple 30 (FIG. 20), a three-layered wall formation is provided, which consists of the portion forming the foot 27, the cramp spike 31 and the bent folded-under material layer constituted by the folded-back portion 34, the crest or vertex 36 and the folded-under portion 35 (see FIG. 18). As regards the modification according to FIG. 22, there is even provided a rolling-in zone for the free end of each cramp spike 31, which exists in that profile by virtue of the practically three-sided free space 40. The corresponding rolled-in material swelling acts like an anchor lying against the underside of the slider bottom 9, which anchor cannot without more pass through the narrowed passage V in a direction opposite to the insertion direction of the cramp spike 31. This solution proves to be especially secure.
The operation of the embodiment according to FIGS. 12 to 23 corresponds to the operation described with respect to the first embodiment.
It will be understood that the foregoing description of preferred embodiments of the present invention is for purposes of illustration only, and that the various structural and operational features herein disclosed are susceptible to a number of modifications and changes none of which entails any departure from the spirit and scope of the present invention as defined in the hereto appended claims.
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The invention relates to a waistband fastener, especially for trousers, skirts or the like, comprising a latch rail (1) fixed to a waistband portion (A) and bearing a plurality of sawtooth-like teeth (3), on which latch rail a slider (2) connected to the other waistband portion (B) is guided in an adjustable and latchable manner. To enable a simple and advantageous handling and operation of the fastener, a latch finger (12) can be selectively brought into and out of engagement with the teeth of the latch rail by means of a transverse shifting of the slider away from and toward the latch rail. In the first case, the latch finger simply slides over the teeth, by virtue of riding up on their sloping faces, when the slider is moved in one direction (arrow y) along the latch rail. In the other case, the latch finger is shifted out of the tooth gaps (4) and clear of the teeth to permit movement of the slider in the opposite direction.
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CROSS-REFERENCE
This application claims priority to and is a continuation of U.S. patent application Ser. No. 14/949,645, filed Nov. 23, 2015, which is a continuation of U.S. patent application Ser. No. 14/742,663, filed Jun. 17, 2015, which is a continuation of U.S. patent application Ser. No. 14/184,047, filed Feb. 19, 2014, which is a continuation of U.S. patent application Ser. No. 13/588,966, filed Aug. 17, 2012, which is a continuation of U.S. patent application Ser. No. 11/328,970, filed Jan. 9, 2006, which claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 60/643,056, filed Jan. 10, 2005, the full disclosures of which are incorporated herein by reference.
FIELD OF THE INVENTION
The present invention relates to ophthalmic surgical procedures and systems.
BACKGROUND OF THE INVENTION
Cataract extraction is one of the most commonly performed surgical procedures in the world with estimates of 2.5 million cases being performed annually in the United States and 9.1 million cases worldwide. This is expected to increase to approximately 13.3 million cases by 2006 globally. This market is composed of various segments including intraocular lenses for implantation, viscoelastic polymers to facilitate surgical maneuvers, disposable instrumentation including ultrasonic phacoemulsification tips, tubing, and various knives and forceps. Modern cataract surgery is typically performed using a technique termed phacoemulsification in which an ultrasonic tip with an associated water stream for cooling purposes is used to sculpt the relatively hard nucleus of the lens after performance of an opening in the anterior lens capsule termed anterior capsulotomy or more recently capsulorhexis. Following these steps as well as removal of residual softer lens cortex by aspiration methods without fragmentation, a synthetic foldable intraocular lens (IOL's) inserted into the eye through a small incision. This technique is associated with a very high rate of anatomic and visual success exceeding 95% in most cases and with rapid visual rehabilitation.
One of the earliest and most critical steps in the procedure is the performance of capsulorhexis. This step evolved from an earlier technique termed can-opener capsulotomy in which a sharp needle was used to perforate the anterior lens capsule in a circular fashion followed by the removal of a circular fragment of lens capsule typically in the range of 5-8 mm in diameter. This facilitated the next step of nuclear sculpting by phacoemulsification. Due to a variety of complications associated with the initial can-opener technique, attempts were made by leading experts in the field to develop a better technique for removal of the anterior lens capsule preceding the emulsification step. These were pioneered by Neuhann, and Gimbel and highlighted in a publication in 1991 (Gimbel, Neuhann, Development Advantages and Methods of the Continuous Curvilinear Capsulorhexis. Journal of Cataract and Refractive Surgery 1991; 17:110-111, incorporated herein by reference). The concept of the capsulorhexis is to provide a smooth continuous circular opening through which not only the phacoemulsification of the nucleus can be performed safely and easily, but also for easy insertion of the intraocular lens. It provides both a clear central access for insertion, a permanent aperture for transmission of the image to the retina by the patient, and also a support of the IOL inside the remaining capsule that would limit the potential for dislocation.
Using the older technique of can-opener capsulotomy, or even with the continuous capsulorhexis, problems may develop related to inability of the surgeon to adequately visualize the capsule due to lack of red reflex, to grasp it with sufficient security, to tear a smooth circular opening of the appropriate size without radial rips and extensions or technical difficulties related to maintenance of the anterior chamber depth after initial opening, small size of the pupil, or the absence of a red reflex due to the lens opacity. Some of the problems with visualization have been minimized through the use of dyes such as methylene blue or indocyanine green. Additional complications arise in patients with weak zonules (typically older patients) and very young children that have very soft and elastic capsules, which are very difficult to mechanically rupture.
Finally, during the intraoperative surgical procedure, and subsequent to the step of anterior continuous curvilinear capsulorhexis, which typically ranges from 5-7 mm in diameter, and prior to IOL insertion the steps of hydrodis section, hydrodilineation and phaco emulsification occur. These are intended to identify and soften the nucleus for the purposes of removal from the eye. These are the longest and thought to be the most dangerous step in the procedure due to the use of pulses of ultrasound that may lead to inadvertent ruptures of the posterior lens capsule, posterior dislocation of lens fragments, and potential damage anteriorly to the corneal endothelium and/or iris and other delicate intraocular structures. The central nucleus of the lens, which undergoes the most opacification and thereby the most visual impairment, is structurally the hardest and requires special techniques. A variety of surgical maneuvers employing ultrasonic fragmentation and also requiring considerable technical dexterity on the part of the surgeon have evolved, including sculpting of the lens, the so-called “divide and conquer technique” and a whole host of similarly creatively named techniques, such as phaco chop, etc. These are all subject to the usual complications associated with delicate intraocular maneuvers (Gimbel. Chapter 15: Principles of Nuclear PhacoEmulsification. In Cataract Surgery Techniques Complications and Management. 2 nd ed. Edited by Steinert et al. 2004: 153-181, incorporated herein by reference.).
Following cataract surgery one of the principal sources of visual morbidity is the slow development of opacities in the posterior lens capsule, which is generally left intact during cataract surgery as a method of support for the lens, to provide good centration of the IOL, and also as a means of preventing subluxation posteriorly into the vitreous cavity. It has been estimated that the complication of posterior lens capsule opacification occurs in approximately 28-50% of patients (Steinert and Richter. Chapter 44 . In Cataract Surgery Techniques Complications and Management. 2 nd ed. Edited by Steinert et al. 2004: pg. 531-544 and incorporated herein by reference). As a result of this problem, which is thought to occur as a result of epithelial and fibrous metaplasia along the posterior lens capsule centrally from small islands of residual epithelial cells left in place near the equator of the lens, techniques have been developed initially using surgical dissection, and more recently the neodymium YAG laser to make openings centrally in a non-invasive fashion. However, most of these techniques can still be considered relatively primitive requiring a high degree of manual dexterity on the part of the surgeon and the creation of a series of high energy pulses in the range of 1 to 10 mJ manually marked out on the posterior lens capsule, taking great pains to avoid damage to the intraocular lens. The course nature of the resulting opening is illustrated clearly in FIG. 44-10, pg. 537 of Steinert and Richter, Chapter 44 of In Cataract Surgery Techniques Complications and Management. 2 nd ed (see complete cite above).
What is needed are ophthalmic methods, techniques and apparatus to advance the standard of care of cataract and other ophthalmic pathologies.
SUMMARY OF THE INVENTION
The techniques and system disclosed herein provide many advantages. Specifically, rapid and precise openings in the lens capsule and fragmentation of the lens nucleus and cortex is enabled using 3-dimensional patterned laser cutting. The duration of the procedure and the risk associated with opening the capsule and fragmentation of the hard nucleus are reduce, while increasing precision of the procedure. The removal of a lens dissected into small segments is performed using a patterned laser scanning and just a thin aspiration needle. The removal of a lens dissected into small segments is performed using patterned laser scanning and using a ultrasonic emulsifier with a conventional phacoemulsification technique or a technique modified to recognize that a segmented lens will likely be more easily removed (i.e., requiring less surgical precision or dexterity) and/or at least with marked reduction in ultrasonic emulsification power, precision and/or duration. There are surgical approaches that enable the formation of very small and geometrically precise opening(s) in precise locations on the lens capsule, where the openings in the lens capsule would be very difficult if not impossible to form using conventional, purely manual techniques. The openings enable greater precision or modifications to conventional ophthalmic procedures as well as enable new procedures. For example, the techniques described herein may be used to facilitate anterior and/or posterior lens removal, implantation of injectable or small foldable IOLs as well as injection of compounds or structures suited to the formation of accommodating IOLs.
Another procedure enabled by the techniques described herein provides for the controlled formation of a hemi-circular or curvilinear flap in the anterior lens surface. Contrast to conventional procedures which require a complete circle or nearly complete circular cut. Openings formed using conventional, manual capsulorhexis techniques rely primarily on the mechanical shearing properties of lens capsule tissue and uncontrollable tears of the lens capsule to form openings. These conventional techniques are confined to the central lens portion or to areas accessible using mechanical cutting instruments and to varying limited degrees utilize precise anatomical measurements during the formation of the tears. In contrast, the controllable, patterned laser techniques described herein may be used to create a semi-circular capsular flap in virtually any position on the anterior lens surface and in virtually any shape. They may be able to seal spontaneously or with an autologous or synthetic tissue glue or other method. Moreover, the controllable, patterned laser techniques described herein also have available and/or utilize precise lens capsule size, measurement and other dimensional information that allows the flap or opening formation while minimizing impact on surrounding tissue. The flap is not limited only to semi-circular but may be any shape that is conducive to follow on procedures such as, for example, injection or formation of complex or advanced IOL devices or so called injectable polymeric or fixed accommodating IOLs.
The techniques disclosed herein may be used during cataract surgery to remove all or a part of the anterior capsule, and may be used in situations where the posterior capsule may need to be removed intraoperatively, for example, in special circumstances such as in children, or when there is a dense posterior capsular opacity which can not be removed by suction after the nucleus has been removed. In the first, second and third years after cataract surgery, secondary opacification of the posterior lens capsule is common and is benefited by a posterior capsulotomy which may be performed or improved utilizing aspects of the techniques disclosed herein.
Because of the precision and atraumatic nature of incisions formed using the techniques herein, it is believed that new meaning is brought to minimally invasive ophthalmic surgery and lens incisions that may be self healing.
In one aspect, a method of making an incision in eye tissue includes generating a beam of light, focusing the beam at a first focal point located at a first depth in the eye tissue, scanning the beam in a pattern on the eye while focused at the first depth, focusing the beam at a second focal point located at a second depth in the eye tissue different than the first depth, and scanning the beam in the pattern on the eye while focused at the second depth.
In another aspect, a method of making an incision in eye tissue includes generating a beam of light, and passing the beam through a multi-focal length optical element so that a first portion of the beam is focused at a first focal point located at a first depth in the eye tissue and a second portion of the beam is focused at a second focal point located at a second depth in the eye tissue different than first depth.
In yet another aspect, a method of making an incision in eye tissue includes generating a beam of light having at least a first pulse of light and a second pulse of light, and focusing the first and second pulses of light consecutively into the eye tissue, wherein the first pulse creates a plasma at a first depth within the eye tissue, and wherein the second pulse arrives before the plasma disappears and is absorbed by the plasma to extend the plasma in the eye tissue along the beam.
In yet one more aspect, a method of making an incision in eye tissue includes generating a beam of light, and focusing the light into the eye tissue to create an elongated column of focused light within the eye tissue, wherein the focusing includes subjecting the light to at least one of a non-spherical lens, a highly focused lens with spherical aberrations, a curved mirror, a cylindrical lens, an adaptive optical element, a prism, and a diffractive optical element.
In another aspect, a method of removing a lens and debris from an eye includes generating a beam of light, focusing the light into the eye to fragment the lens into pieces, removing the pieces of lens, and then focusing the light into the eye to ablate debris in the eye.
In one more aspect, a method of removing a lens from a lens capsule in an eye includes generating a beam of light, focusing the light into the eye to form incisions in the lens capsule, inserting an ultrasonic probe through the incision and into the lens capsule to break the lens into pieces, removing the lens pieces from the lens capsule, rinsing the lens capsule to remove endothermial cells therefrom, and inserting at least one of a synthetic. foldable intraocular lens or an optically transparent gel into the lens capsule.
In another aspect, an ophthalmic surgical system for treating eye tissue includes a light source for generating a beam of light, a delivery system for focusing the beam onto the eye tissue, a controller for controlling the light source and the delivery system such that the light beam is focused at multiple focal points in the eye tissue at multiple depths within the eye tissue.
In yet another aspect, an ophthalmic surgical system for treating eye tissue includes a light source for generating a beam of light having at least a first pulse of light and a second pulse of light, a delivery system for focusing the beam onto the eye tissue, a controller for controlling the light source and the delivery system such that the first and second pulses of light are consecutively focused onto the eye tissue, wherein the first pulse creates a plasma at a first depth within the eye tissue, and wherein the second pulse is arrives before the plasma disappears and absorbed by the plasma to extend the plasma in the eye tissue along the beam.
In one more aspect, an ophthalmic surgical system for treating eye tissue includes a light source for generating a beam of light, a delivery system for focusing the beam onto the eye tissue, the delivery system including at least one of a non-spherical lens, a highly focused lens with spherical aberrations, a curved mirror, a cylindrical lens, an adaptive optical element, a prism, and a diffractive optical element, and a controller for controlling the light source and the delivery system such that an elongated column of focused light within the eye tissue is created.
Other objects and features of the present invention will become apparent by a review of the specification, claims and appended figures.
INCORPORATION BY REFERENCE
All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.
BRIEF DESCRIPTION OF THE DRAWINGS
The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:
FIG. 1 is a plan diagram of a system that projects or scans an optical beam into a patient's eye.
FIG. 2 is a diagram of the anterior chamber of the eye and the laser beam producing plasma at the focal point on the lens capsule.
FIG. 3 is a planar view of the iris and lens with a circular pattern for the anterior capsulotomy (capsulorexis).
FIG. 4 is a diagram of the line pattern applied across the lens for OCT measurement of the axial profile of the anterior chamber.
FIG. 5 is a diagram of the anterior chamber of the eye and the 3-dimensional laser pattern applied across the lens capsule.
FIG. 6 is an axially-elongated plasma column produced in the focal zone by sequential application of a burst of pulses ( 1 , 2 , and 3 ) with a delay shorter than the plasma life time.
FIGS. 7A-7B are multi-segmented lenses for focusing the laser beam into 3 points along the same axis.
FIGS. 7C-7D are multi-segmented lenses with co-axial and off-axial segments having focal points along the same axis but different focal distances F 1 , F 2 , F 3 .
FIG. 8 is an axial array of fibers ( 1 , 2 , 3 ) focused with a set of lenses into multiple points ( 1 , 2 , 3 ) and thus producing plasma at different depths inside the tissue ( 1 , 2 , 3 ).
FIG. 9A and FIG. 9B are diagrams illustrating examples of the patterns that can be applied for nucleus segmentation.
FIG. 10A-C is a planar view of some of the combined patterns for segmented capsulotomy and phaco-fragmentation.
FIG. 11 is a plan diagram of one system embodiment that projects or scans an optical beam into a patient's eye.
FIG. 12 is a plan diagram of another system embodiment that projects or scans an optical beam into a patient's eye.
FIG. 13 is a plan diagram of yet another system embodiment that projects or scans an optical beam into a patient's eye.
FIG. 14 is a flow diagram showing the steps utilized in a “track and treat” approach to material removal.
FIG. 15 is a flow diagram showing the steps utilized in a “track and treat” approach to material removal that employs user input.
FIG. 16 is a perspective view of a transverse focal zone created by an anamorphic optical scheme.
FIGS. 17A-17C are perspective views of an anamorphic telescope configuration for constructing an inverted Keplerian telescope.
FIG. 18 is a side view of prisms used to extend the beam along a single meridian.
FIG. 19 is a top view illustrating the position and motion of a transverse focal volume on the eye lens.
FIG. 20 illustrates fragmentation patterns of an ocular lens produced by one embodiment of the present invention.
FIG. 21 illustrates circular incisions of an ocular lens produced by one embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention can be implemented by a system that projects or scans an optical beam into a patient's eye 1 , such as the system shown in FIG. 1 . The system includes a light source 10 (e.g. laser, laser diode, etc.), which may be controlled by control electronics 12 , via an input and output device 14 , to create optical beam 11 (either cw or pulsed). Control electronics 12 may be a computer, microcontroller, etc. Scanning may be achieved by using one or more moveable optical elements (e.g. lenses, gratings, or as shown in FIG. 1 a mirror(s) 16 ) which also may be controlled by control electronics 12 , via input and output device 14 . Mirror 16 may be tilted to deviate the optical beam 11 as shown in FIG. 1 , and direct beam 11 towards the patient's eye 1 . An optional ophthalmic lens 18 can be used to focus the optical beam 11 into the patient's eye 1 . The positioning and character of optical beam 11 and/or the scan pattern it forms on the eye may be further controlled by use of an input device 20 such as a joystick, or any other appropriate user input device.
Techniques herein include utilizing a light source 10 such as a surgical laser configured to provide one or more of the following parameters:
1) pulse energy up to 1 μJ repetition rate up to 1 MHz, pulse duration <1 ps
2) pulse energy up to 10 μJ rep. rate up to 100 kHz, pulse duration <1 ps.
3) Pulse energy up to 1000 μJ, rep rate up to 1 kHz, pulse duration <3 ps.
Additionally, the laser may use wavelengths in a variety of ranges including in the near-infrared range: 800-1100 nm. In one aspect, near-infrared wavelengths are selected because tissue absorption and scattering is reduced. Additionally, a laser can be configured to provide low energy ultrashort pulses of near-infrared radiation with pulse durations below 10 ps or below 1 ps, alone or in combination with pulse energy not exceeding 100 μJ, at high repetition rate including rates above 1 kHz, and above 10 kHz.
Short pulsed laser light focused into eye tissue 2 will produce dielectric breakdown at the focal point, rupturing the tissue 2 in the vicinity of the photo-induced plasma (see FIG. 2 ). The diameter d of the focal point is given by d=λF/D b , where F is the focal length of the last focusing element, D b is the beam diameter on the last lens, and λ is the wavelength. For a focal length F=160 mm, beam diameter on the last lens D b =10 mm, and wavelength λ=1.04 um, the focal spot diameter will be d≈λ/(2.NA)≈λF/D b =15 μm, where the numerical aperture of the focusing optics, NA≈D b /(2F).
To provide for continuous cutting, the laser spots should not be separated by more than a width of the crater produced by the laser pulse in tissue. Assuming the rupture zone being R=15 μm (at low energies ionization might occur in the center of the laser spot and not expand to the full spot size), and assuming the maximal diameter of the capsulotomy circle being D c =8 mm, the number of required pulses will be: N=πD c /R=1675 to provide a circular cut line 22 around the circumference of the eye lens 3 as illustrated in FIG. 3 . For smaller diameters ranging from 5-7 mm, the required number of pulses would be less. If the rupture zone were larger (e.g. 50 μm), the number of pulses would drop to N=503.
To produce an accurate circular cut, these pulses should be delivered to tissue over a short eye fixation time. Assuming the fixation time t=0.2 s, laser repetition rate should be: r=N/t=8.4 kHz. If the fixation time were longer, e.g. 0.5 s, the required rep. rate could be reduced to 3.4 kHz. With a rupture zone of 50 μm the rep. rate could further drop to 1 kHz.
Threshold radiant exposure of the dielectric breakdown with 4 ns pulses is about Φ=100 J/cm 2 . With a focal spot diameter being d=15 μm, the threshold pulse energy will be E th =Φ*πd 2 /4=176 μJ. For stable and reproducible operation, pulse energy should exceed the threshold by at least a factor of 2, so pulse energy of the target should be E=352 μJ. The creation of a cavitation bubble might take up to 10% of the pulse energy, i.e. E b =35 μJ. This corresponds to a bubble diameter
d
b
=
6
E
b
π
P
a
3
=
48
µm
.
The energy level can be adjusted to avoid damage to the corneal endothelium. As such, the threshold energy of the dielectric breakdown could be minimized by reducing the pulse duration, for example, in the range of approximately 0.1-1 ps. Threshold radiant exposure, Φ, for dielectric breakdown for 100 fs is about Φ=2 J/cm 2 ; for 1 ps it is Φ=2.5 J/cm 2 . Using the above pulse durations, and a focal spot diameter d=15 μm, the threshold pulse energies will be E th =Φ*πd 2 /4=3.5 and 4.4 μJ for 100 fs and 1 ps pulses, respectively. The pulse energy could instead be selected to be a multiple of the threshold energy, for example, at least a factor of 2. If a factor of 2 is used, the pulse energies on the target would be E th =7 and 9 μJ, respectively. These are only two examples. Other pulse energy duration times, focal spot sizes and threshold energy levels are possible and are within the scope of the present invention.
A high repetition rate and low pulse energy can be utilized for tighter focusing of the laser beam. In one specific example, a focal distance of F=50 mm is used while the beam diameter remains D b =10 mm, to provide focusing into a spot of about 4 μm in diameter. Aspherical optics can also be utilized. An 8 mm diameter opening can be completed in a time of 0.2 s using a repetition rate of about 32 kHz.
The laser 10 and controller 12 can be set to locate the surface of the capsule and ensure that the beam will be focused on the lens capsule at all points of the desired opening. Imaging modalities and techniques described herein, such as for example, Optical Coherence Tomography (OCT) or ultrasound, may be used to determine the location and measure the thickness of the lens and lens capsule to provide greater precision to the laser focusing methods, including 2D and 3D patterning. Laser focusing may also be accomplished using one or more methods including direct observation of an aiming beam, Optical Coherence Tomography (OCT), ultrasound, or other known ophthalmic or medical imaging modalities and combinations thereof.
As shown in FIG. 4 , OCT imaging of the anterior chamber can be performed along a simple linear scan 24 across the lens using the same laser and/or the same scanner used to produce the patterns for cutting. This scan will provide information about the axial location of the anterior and posterior lens capsule, the boundaries of the cataract nucleus, as well as the depth of the anterior chamber. This information may then be loaded into the laser 3-D scanning system, and used to program and control the subsequent laser assisted surgical procedure. The information may be used to determine a wide variety of parameters related to the procedure such as, for example, the upper and lower axial limits of the focal planes for cutting the lens capsule and segmentation of the lens cortex and nucleus, the thickness of the lens capsule among others. The imaging data may be averaged across a 3-line pattern as shown in FIG. 9 .
An example of the results of such a system on an actual human crystalline lens is shown in FIG. 20 . A beam of 10 μJ, 1 ps pulses delivered at a pulse repetition rate of 50 kHz from a laser operating at a wavelength of 1045 nm was focused at NA=0.05 and scanned from the bottom up in a pattern of 4 circles in 8 axial steps. This produced the fragmentation pattern in the ocular lens shown in FIG. 20 . FIG. 21 shows in detail the resultant circular incisions, which measured ˜10 μm in diameter, and ˜100 μm in length.
FIG. 2 illustrates an exemplary illustration of the delineation available using the techniques described herein to anatomically define the lens. As can be seen in FIG. 2 , the capsule boundaries and thickness, the cortex, epinucleus and nucleus are determinable. It is believed that OCT imaging may be used to define the boundaries of the nucleus, cortex and other structures in the lens including, for example, the thickness of the lens capsule including all or a portion of the anterior or posterior capsule. In the most general sense, one aspect of the present invention is the use of ocular imaging data obtained as described herein as an input into a laser scanning and/or pattern treatment algorithm or technique that is used to as a guide in the application of laser energy in novel laser assisted ophthalmic procedures. In fact, the imaging and treatment can be performed using the same laser and the same scanner. While described for use with lasers, other energy modalities may also be utilized.
It is to be appreciated that plasma formation occurs at the waist of the beam. The axial extent of the cutting zone is determined by the half-length L of the laser beam waist, which can be expressed as: L˜λ/(4.NA 2 )=dF/D b . Thus the lower the NA of the focusing optics, the longer waist of the focused beam, and thus a longer fragmentation zone can be produced. For F=160 mm, beam diameter on the last lens D b =10 mm, and focal spot diameter d=15 μm, the laser beam waist half-length L would be 240 μm.
With reference to FIG. 5 , a three dimensional application of laser energy 26 can be applied across the capsule along the pattern produced by the laser-induced dielectric breakdown in a number of ways such as, for example:
1) Producing several circular or other pattern scans consecutively at different depths with a step equal to the axial length of the rupture zone. Thus, the depth of the focal point (waist) in the tissue is stepped up or down with each consecutive scan. The laser pulses are sequentially applied to the same lateral pattern at different depths of tissue using, for example, axial scanning of the focusing elements or adjusting the optical power of the focusing element while, optionally, simultaneously or sequentially scanning the lateral pattern. The adverse result of laser beam scattering on bubbles, cracks and/or tissue fragments prior to reaching the focal point can be avoided by first producing the pattern/focusing on the maximal required depth in tissue and then, in later passes, focusing on more shallow tissue spaces. Not only does this “bottom up” treatment technique reduce unwanted beam attenuation in tissue above the target tissue layer, but it also helps protect tissue underneath the target tissue layer. By scattering the laser radiation transmitted beyond the focal point on gas bubbles, cracks and/or tissue fragments which were produced by the previous scans, these defects help protect the underlying retina. Similarly, when segmenting a lens, the laser can be focused on the most posterior portion of the lens and then moved more anteriorly as the procedure continues.
2) Producing axially-elongated rupture zones at fixed points by:
a) Using a sequence of 2-3 pulses in each spot separated by a few ps. Each pulse will be absorbed by the plasma 28 produced by the previous pulse and thus will extend the plasma 28 upwards along the beam as illustrated in FIG. 6A . In this approach, the laser energy should be 2 or 3 times higher, i.e. 20-30 μJ. Delay between the consecutive pulses should be longer than the plasma formation time (on the order of 0.1 ps) but not exceed the plasma recombination time (on the order of nanoseconds)
b) Producing an axial sequence of pulses with slightly different focusing points using multiple co-axial beams with different pre-focusing or multifocal optical elements. This can be achieved by using multi-focal optical elements (lenses, mirrors, diffractive optics, etc.). For example, a multi-segmented lens 30 can be used to focus the beam into multiple points (e.g. three separate points) along the same axis, using for example co-axial (see FIGS. 7A-7C ) or off-coaxial (see FIG. 7D ) segments to produce varying focal lengths (e.g. F 1 , F 2 , F 3 ). The multi-focal element 30 can be co-axial, or off-axis-segmented, or diffractive. Co-axial elements may have more axially-symmetric focal points, but will have different sizes due to the differences in beam diameters in each segment. Off-axial elements might have less symmetric focal points but all the elements can produce the foci of the same sizes.
c) Producing an elongated focusing column (as opposed to just a discrete number of focal points) using: (1) non-spherical (aspherical) optics, or (2) utilizing spherical aberrations in a lens with a high F number, or (3) diffractive optical element (hologram).
d) Producing an elongated zone of ionization using multiple optical fibers. For example, an array of optical fibers 32 of different lengths can be imaged with a set of lenses 34 into multiple focal points at different depths inside the tissue as shown in FIG. 8 .
Patterns of Scanning:
For anterior and posterior capsulotomy, the scanning patterns can be circular and spiral, with a vertical step similar to the length of the rupture zone. For segmentation of the eye lens 3 , the patterns can be linear, planar, radial, radial segments, circular, spiral, curvilinear and combinations thereof including patterning in two and/or three dimensions. Scans can be continuous straight or curved lines, or one or more overlapping or spaced apart spots and/or line segments. Several scan patterns 36 are illustrated in FIGS. 9A and 9B , and combinations of scan patterns 38 are illustrated in FIGS. 10A-10C . Beam scanning with the multifocal focusing and/or patterning systems is particularly advantageous to successful lens segmentation since the lens thickness is much larger than the length of the beam waist axial. In addition, these and other 2D and 3D patterns may be used in combination with OCT to obtain additional imaging, anatomical structure or make-up (i.e., tissue density) or other dimensional information about the eye including but not limited to the lens, the cornea, the retina and as well as other portions of the eye.
The exemplary patterns allow for dissection of the lens cortex and nucleus into fragments of such dimensions that they can be removed simply with an aspiration needle, and can be used alone to perform capsulotomy. Alternatively, the laser patterning may be used to pre-fragment or segment the nucleus for later conventional ultrasonic phacoemulsification. In this case however, the conventional phacoemulsification would be less than a typical phacoemulsification performed in the absence of the inventive segmenting techniques because the lens has been segmented. As such, the phacoemulsification procedure would likely require less ultrasonic energy to be applied to the eye, allowing for a shortened procedure or requiring less surgical dexterity.
Complications due to the eye movements during surgery can be reduced or eliminated by performing the patterned laser cutting very rapidly (e.g. within a time period that is less than the natural eye fixation time). Depending on the laser power and repetition rate, the patterned cutting can be completed between 5 and 0.5 seconds (or even less), using a laser repetition rate exceeding 1 kHz.
The techniques described herein may be used to perform new ophthalmic procedures or improve existing procedures, including anterior and posterior capsulotomy, lens fragmentation and softening, dissection of tissue in the posterior pole (floaters, membranes, retina), as well as incisions in other areas of the eye such as, but not limited to, the sclera and iris.
Damage to an IOL during posterior capsulotomy can be reduced or minimized by advantageously utilizing a laser pattern initially focused beyond the posterior pole and then gradually moved anteriorly under visual control by the surgeon alone or in combination with imaging data acquired using the techniques described herein.
For proper alignment of the treatment beam pattern, an alignment beam and/or pattern can be first projected onto the target tissue with visible light (indicating where the treatment pattern will be projected. This allows the surgeon to adjust the size, location and shape of the treatment pattern. Thereafter, the treatment pattern can be rapidly applied to the target tissue using an automated 3 dimensional pattern generator (in the control electronics 12 ) by a short pulsed cutting laser having high repetition rate.
In addition, and in particular for capsulotomy and nuclear fragmentation, an automated method employing an imaging modality can be used, such as for example, electro-optical, OCT, acoustic, ultrasound or other measurement, to first ascertain the maximum and minimum depths of cutting as well as the size and optical density of the cataract nucleus. Such techniques allow the surgeon account for individual differences in lens thickness and hardness, and help determine the optimal cutting contours in patients. The system for measuring dimensions of the anterior chamber using OCT along a line, and/or pattern (2D or 3D or others as described herein) can be integrally the same as the scanning system used to control the laser during the procedure. As such, the data including, for example, the upper and lower boundaries of cutting, as well as the size and location of the nucleus, can be loaded into the scanning system to automatically determine the parameters of the cutting (i.e., segmenting or fracturing) pattern. Additionally, automatic measurement (using an optical, electro-optical, acoustic, or OCT device, or some combination of the above) of the absolute and relative positions and/or dimensions of a structure in the eye (e.g. the anterior and posterior lens capsules, intervening nucleus and lens cortex) for precise cutting, segmenting or fracturing only the desired tissues (e.g. lens nucleus, tissue containing cataracts, etc.) while minimizing or avoiding damage to the surrounding tissue can be made for current and/or future surgical procedures. Additionally, the same ultrashort pulsed laser can be used for imaging at a low pulse energy, and then for surgery at a high pulse energy.
The use of an imaging device to guide the treatment beam may be achieved many ways, such as those mentioned above as well as additional examples explained next (which all function to characterize tissue, and continue processing it until a target is removed). For example, in FIG. 11 , a laser source LS and (optional) aiming beam source AIM have outputs that are combined using mirror DM 1 (e.g. dichroic mirror). In this configuration, laser source LS may be used for both therapeutics and diagnostics. This is accomplished by means of mirror M 1 which serves to provide both reference input R and sample input S to an OCT Interferometer by splitting the light beam B (centerlines shown) from laser source LS. Because of the inherent sensitivity of OCT Interferometers, mirror M 1 may be made to reflect only a small portion of the delivered light. Alternatively, a scheme employing polarization sensitive pickoff mirrors may be used in conjunction with a quarter wave plate (not shown) to increase the overall optical efficiency of the system. Lens L 1 may be a single element or a group of elements used to adjust the ultimate size or location along the z-axis of the beam B disposed to the target at point P. When used in conjunction with scanning in the X & Y axes, this configuration enables 3-dimensional scanning and/or variable spot diameters (i.e. by moving the focal point of the light along the z-axis).
In this example, transverse (XY) scanning is achieved by using a pair of orthogonal galvanometric mirrors G 1 & G 2 which may provide 2-dimensional random access scanning of the target. It should be noted that scanning may be achieved in a variety of ways, such as moving mirror M 2 , spinning polygons, translating lenses or curved mirrors, spinning wedges, etc. and that the use of galvanometric scanners does not limit the scope of the overall design. After leaving the scanner, light encounters lens L 2 which serves to focus the light onto the target at point P inside the patient's eye EYE. An optional ophthalmic lens OL may be used to help focus the light. Ophthalmic lens OL may be a contact lens and further serve to dampen any motion of eye EYE, allowing for more stable treatment. Lens L 2 may be made to move along the z-axis in coordination with the rest of the optical system to provide for 3-dimensional scanning, both for therapy and diagnosis. In the configuration shown, lens L 2 ideally is moved along with the scanner G 1 & G 2 to maintain telecentricity. With that in mind, one may move the entire optical assembly to adjust the depth along the z-axis. If used with ophthalmic lens OL, the working distance may be precisely held. A device such as the Thorlabs EAS504 precision stepper motor can be used to provide both the length of travel as well as the requisite accuracy and precision to reliably image and treat at clinically meaningful resolutions. As shown it creates a telecentric scan, but need not be limited to such a design.
Mirror M 2 serves to direct the light onto the target, and may be used in a variety of ways. Mirror M 2 could be a dichroic element that the user looks through in order to visualize the target directly or using a camera, or may be made as small as possible to provide an opportunity for the user to view around it, perhaps with a binocular microscope. If a dichroic element is used, it may be made to be photopically neutral to avoid hindering the user's view. An apparatus for visualizing the target tissue is shown schematically as element V, and is preferably a camera with an optional light source for creating an image of the target tissue. The optional aiming beam AIM may then provide the user with a view of the disposition of the treatment beam, or the location of the identified targets. To display the target only, AIM may be pulsed on when the scanner has positioned it over an area deemed to be a target. The output of visualization apparatus V may be brought back to the system via the input/output device IO and displayed on a screen, such as a graphical user interface GUI. In this example, the entire system is controlled by the controller CPU, and data moved through input/output device IO. Graphical user interface GUI may be used to process user input, and display the images gathered by both visualization apparatus V and the OCT interferometer. There are many possibilities for the configuration of the OCT interferometer, including time and frequency domain approaches, single and dual beam methods, etc, as described in U.S. Pat. Nos. 5,748,898; 5,748,352; 5,459,570; 6,111,645; and 6,053,613 (which are incorporated herein by reference.
Information about the lateral and axial extent of the cataract and localization of the boundaries of the lens capsule will then be used for determination of the optimal scanning pattern, focusing scheme, and laser parameters for the fragmentation procedure. Much if not all of this information can be obtained from visualization of the target tissue. For example, the axial extent of the fragmentation zone of a single pulse should not exceed the distance between (a) the cataract and the posterior capsule, and (b) the anterior capsule and the corneal endothelium. In the cases of a shallow anterior chamber and/or a large cataract, a shorter fragmentation zone should be selected, and thus more scanning planes will be required. Conversely, for a deep anterior chamber and/or a larger separation between the cataract and the posterior capsule a longer fragmentation zone can be used, and thus less planes of scanning will be required. For this purpose an appropriate focusing element will be selected from an available set. Selection of the optical element will determine the width of the fragmentation zone, which in turn will determine the spacing between the consecutive pulses. This, in turn, will determine the ratio between the scanning rate and repetition rate of the laser pulses. In addition, the shape of the cataract will determine the boundaries of the fragmentation zone and thus the optimal pattern of the scanner including the axial and lateral extent of the fragmentation zone, the ultimate shape of the scan, number of planes of scanning, etc.
FIG. 12 shows an alternate embodiment in which the imaging and treatment sources are different. A dichroic mirror DM 2 has been added to the configuration of FIG. 11 to combine the imaging and treatment light, and mirror M 1 has been replaced by beam splitter BS which is highly transmissive at the treatment wavelength, but efficiently separates the light from the imaging source SLD for use in the OCT Interferometer. Imaging source SLD may be a superluminescent diode having a spectral output that is nominally 50 nm wide, and centered on or around 835 nm, such as the SuperLum SLD-37. Such a light source is well matched to the clinical application, and sufficiently spectrally distinct from the treatment source, thus allowing for elements DM and BS to be reliably fabricated without the necessarily complicated and expensive optical coatings that would be required if the imaging and treatment sources were closer in wavelength.
FIG. 13 shows an alternate embodiment incorporating a confocal microscope CM for use as an imaging system. In this configuration, mirror M 1 reflects a portion of the backscattered light from beam B into lens L 3 . Lens L 3 serves to focus this light through aperture A (serving as a spatial filter) and ultimately onto detector D. As such, aperture A and point P are optically conjugate, and the signal received by detector D is quite specific when aperture A is made small enough to reject substantially the entire background signal. This signal may thus be used for imaging, as is known in the art. Furthermore, a fluorophore may be introduced into the target to allow for specific marking of either target or healthy tissue. In this approach, the ultrafast laser may be used to pump the absorption band of the fluorophore via a multiphoton process or an alternate source (not shown) could be used in a manner similar to that of FIG. 12 .
FIG. 14 is a flowchart outlining the steps utilized in a “track and treat” approach to material removal. First an image is created by scanning from point to point, and potential targets identified. When the treatment beam is disposed over a target, the system can transmit the treatment beam, and begin therapy. The system may move constantly treating as it goes, or dwell in a specific location until the target is fully treated before moving to the next point.
The system operation of FIG. 14 could be modified to incorporate user input. As shown in FIG. 15 , a complete image is displayed to the user, allowing them to identify the target(s). Once identified, the system can register subsequent images, thus tracking the user defined target(s). Such a registration scheme may be implemented in many different ways, such as by use of the well known and computationally efficient Sobel or Canny edge detection schemes. Alternatively, one or more readily discernable marks may be made in the target tissue using the treatment laser to create a fiduciary reference without patient risk (since the target tissue is destined for removal).
In contrast to conventional laser techniques, the above techniques provide (a) application of laser energy in a pattern, (b) a high repetition rate so as to complete the pattern within the natural eye fixation time, (c) application of sub-ps pulses to reduce the threshold energy, and (d) the ability to integrate imaging and treatment for an automated procedure.
Laser Delivery System
The laser delivery system in FIG. 1 can be varied in several ways. For example, the laser source could be provided onto a surgical microscope, and the microscope's optics used by the surgeon to apply the laser light, perhaps through the use of a provided console. Alternately, the laser and delivery system would be separate from the surgical microscope and would have an optical system for aligning the aiming beam for cutting. Such a system could swing into position using an articulating arm attached to a console containing the laser at the beginning of the surgery, and then swing away allowing the surgical microscope to swing into position.
The pattern to be applied can be selected from a collection of patterns in the control electronics 12 , produced by the visible aiming beam, then aligned by the surgeon onto the target tissue, and the pattern parameters (including for example, size, number of planar or axial elements, etc.) adjusted as necessary for the size of the surgical field of the particular patient (level of pupil dilation, size of the eye, etc.). Thereafter, the system calculates the number of pulses that should be applied based on the size of the pattern. When the pattern calculations are complete, the laser treatment may be initiated by the user (i.e., press a pedal) for a rapid application of the pattern with a surgical laser.
The laser system can automatically calculate the number of pulses required for producing a certain pattern based on the actual lateral size of the pattern selected by surgeon. This can be performed with the understanding that the rupture zone by the single pulse is fixed (determined by the pulse energy and configuration of the focusing optics), so the number of pulses required for cutting a certain segment is determined as the length of that segment divided by the width of the rupture zone by each pulse. The scanning rate can be linked to the repetition rate of the laser to provide a pulse spacing on tissue determined by the desired distance. The axial step of the scanning pattern will be determined by the length of the rupture zone, which is set by the pulse energy and the configuration of the focusing optics.
Fixation Considerations
The methods and systems described herein can be used alone or in combination with an aplanatic lens (as described in, for example, the U.S. Pat. No. 6,254,595, incorporated herein by reference) or other device to configure the shape of the cornea to assist in the laser methods described herein. A ring, forceps or other securing means may be used to fixate the eye when the procedure exceeds the normal fixation time of the eye. Regardless whether an eye fixation device is used, patterning and segmenting methods described herein may be further subdivided into periods of a duration that may be performed within the natural eye fixation time.
Another potential complication associated with a dense cutting pattern of the lens cortex is the duration of treatment: If a volume of 6×6×4 mm=144 mm 3 of lens is segmented, it will require N=722,000 pulses. If delivered at 50 kHz, it will take 15 seconds, and if delivered at 10 kHz it will take 72 seconds. This is much longer than the natural eye fixation time, and it might require some fixation means for the eye. Thus, only the hardened nucleus may be chosen to be segmented to ease its removal. Determination of its boundaries with the OCT diagnostics will help to minimize the size of the segmented zone and thus the number of pulses, the level of cumulative heating, and the treatment time. If the segmentation component of the procedure duration exceeds the natural fixation time, then the eye may be stabilized using a conventional eye fixation device.
Thermal Considerations
In cases where very dense patterns of cutting are needed or desired, excess accumulation of heat in the lens may damage the surrounding tissue. To estimate the maximal heating, assume that the bulk of the lens is cut into cubic pieces of 1 mm in size. If tissue is dissected with E 1 =10 uJ pulses fragmenting a volume of 15 um in diameter and 200 um in length per pulse, then pulses will be applied each 15 um. Thus a 1×1 mm plane will require 66×66=4356 pulses. The 2 side walls will require 2×66×5=660 pulses, thus total N=5016 pulses will be required per cubic mm of tissue. Since all the laser energy deposited during cutting will eventually be transformed into heat, the temperature elevation will be DT=(E 1 *N)/pcV=50.16 mJ/(4.19 mJ/K)=12 K. This will lead to maximal temperature T=37+12° C.=49° C. This heat will dissipate in about one minute due to heat diffusion. Since peripheral areas of the lens will not be segmented (to avoid damage to the lens capsule) the average temperature at the boundaries of the lens will actually be lower. For example, if only half of the lens volume is fragmented, the average temperature elevation at the boundaries of the lens will not exceed 6° C. (T=43° C.) and on the retina will not exceed 0.1 C. Such temperature elevation can be well tolerated by the cells and tissues. However, much higher temperatures might be dangerous and should be avoided.
To reduce heating, a pattern of the same width but larger axial length can be formed, so these pieces can still be removed by suction through a needle. For example, if the lens is cut into pieces of 1×1×4 mm in size, a total of N=6996 pulses will be required per 4 cubic mm of tissue. The temperature elevation will be DT=(E 1 *N)/pcV=69.96 mJ/(4.19 mJ/K)/4=1.04 K. Such temperature elevation can be well tolerated by the cells and tissues.
An alternative solution to thermal limitations can be the reduction of the total energy required for segmentation by tighter focusing of the laser beam. In this regime a higher repetition rate and low pulse energy may be used. For example, a focal distance of F=50 mm and a beam diameter of D b =10 mm would allow for focusing into a spot of about 4 μm in diameter. In this specific example, repetition rate of about 32 kHz provides an 8 mm diameter circle in about 0.2 s.
To avoid retinal damage due to explosive vaporization of melanosomes following absorption of the short laser pulse the laser radiant exposure on the RPE should not exceed 100 mJ/cm 2 . Thus NA of the focusing optics should be adjusted such that laser radiant exposure on the retina will not exceed this safety limit. With a pulse energy of 10 μJ, the spot size on retina should be larger than 0.1 mm in diameter, and with a 1 mJ pulse it should not be smaller than 1 mm. Assuming a distance of 20 mm between lens and retina, these values correspond to minimum numerical apertures of 0.0025 and 0.025, respectively.
To avoid thermal damage to the retina due to heat accumulation during the lens fragmentation the laser irradiance on the retina should not exceed the thermal safety limit for near-IR radiation—on the order of 0.6 W/cm 2 . With a retinal zone of about 10 mm in diameter (8 mm pattern size on a lens+1 mm on the edges due to divergence) it corresponds to total power of 0.5 W on the retina.
Transverse Focal Volume
It is also possible to create a transverse focal volume 50 instead of an axial focal volume described above. An anamorphic optical scheme may used to produce a focal zone 39 that is a “line” rather than a single point, as is typical with spherically symmetric elements (see FIG. 16 ). As is standard in the field of optical design, the term “anamorphic” is meant herein to describe any system which has different equivalent focal lengths in each meridian. It should be noted that any focal point has a discrete depth of field. However, for tightly focused beams, such as those required to achieve the electric field strength sufficient to disrupt biological material with ultrashort pulses (defined as t pulse <10 ps), the depth of focus is proportionally short.
Such a 1-dimensional focus may be created using cylindrical lenses, and/or mirrors. An adaptive optic may also be used, such as a MEMS mirror or a phased array. When using a phased array, however, careful attention should be paid to the chromatic effects of such a diffractive device. FIGS. 17A-17C illustrate an anamorphic telescope configuration, where cylindrical optics 40 a/b and spherical lens 42 are used to construct an inverted Keplerian telescope along a single meridian (see FIG. 17A ) thus providing an elongated focal volume transverse to the optical axis (see FIG. 17C ). Compound lenses may be used to allow the beam's final dimensions to be adjustable.
FIG. 18 shows the use of a pair of prisms 46 a/b to extend the beam along a single meridian, shown as CA. In this example, CA is reduced rather than enlarged to create a linear focal volume.
The focus may also be scanned to ultimately produce patterns. To effect axial changes, the final lens may be made to move along the system's z-axis to translate the focus into the tissue. Likewise, the final lens may be compound, and made to be adjustable. The 1-dimensional focus may also be rotated, thus allowing it to be aligned to produce a variety of patterns, such as those shown in FIGS. 9 and 10 . Rotation may be achieved by rotating the cylindrical element itself. Of course, more than a single element may be used. The focus may also be rotated by using an additional element, such as a Dove prism (not shown). If an adaptive optic is used, rotation may be achieved by rewriting the device, thus streamlining the system design by eliminating a moving part.
The use of a transverse line focus allows one to dissect a cataractous lens by ablating from the posterior to the anterior portion of the lens, thus planing it. Furthermore, the linear focus may also be used to quickly open the lens capsule, readying it for extraction. It may also be used for any other ocular incision, such as the conjunctiva, etc. (see FIG. 19 ).
Cataract Removal Using a Track and Treat Approach
A “track and treat” approach is one that integrates the imaging and treatment aspect of optical eye surgery, for providing an automated approach to removal of debris such as cataractous and cellular material prior to the insertion of an IOL. An ultrafast laser is used to fragment the lens into pieces small enough to be removed using an irrigating/aspirating probe of minimal size without necessarily rupturing the lens capsule. An approach such as this that uses tiny, self-sealing incisions may be used to provide a capsule for filling with a gel or elastomeric IOL. Unlike traditional hard IOLS that require large incisions, a gel or liquid may be used to fill the entire capsule, thus making better use of the body's own accommodative processes. As such, this approach not only addresses cataract, but presbyopia as well.
Alternately, the lens capsule can remain intact, where bilateral incisions are made for aspirating tips, irrigating tips, and ultrasound tips for removing the bulk of the lens. Thereafter, the complete contents of the bag/capsule can be successfully rinsed/washed, which will expel the debris that can lead to secondary cataracts. Then, with the lens capsule intact, a minimal incision is made for either a foldable IOL or optically transparent gel injected through incision to fill the bag/capsule. The gel would act like the natural lens with a larger accommodating range.
It is to be understood that the present invention is not limited to the embodiment(s) described above and illustrated herein, but encompasses any and all variations falling within the scope of the appended claims. For example, materials, processes and numerical examples described above are exemplary only, and should not be deemed to limit the claims. Multi-segmented lens 30 can be used to focus the beam simultaneously at multiple points not axially overlapping (i.e. focusing the beam at multiple foci located at different lateral locations on the target tissue). Further, as is apparent from the claims and specification, not all method steps need be performed in the exact order illustrated or claimed, but rather in any order that accomplishes the goals of the surgical procedure.
DETAILED DESCRIPTION OF THE INVENTION
While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.
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A system for ophthalmic surgery on an eye includes: a pulsed laser which produces a treatment beam; an OCT imaging assembly capable of creating a continuous depth profile of the eye; an optical scanning system configured to position a focal zone of the treatment beam to a targeted location in three dimensions in one or more floaters in the posterior pole. The system also includes one or more controllers programmed to automatically scan tissues of the patient's eye with the imaging assembly; identify one or more boundaries of the one or more floaters based at least in part on the image data; iii. identify one or more treatment regions based upon the boundaries; and operate the optical scanning system with the pulsed laser to produce a treatment beam directed in a pattern based on the one or more treatment regions.
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BACKGROUND
1. Field of the Invention
This invention relates to machines which can be used for framing fabrics or material into corresponding male and female hoops as support members (a process known as "hooping"), the members maintaining a portion of fabric in a stretched, taut position. After an individual hoops a piece of fabric or material (the individual is known as a "hooper,") the hooped fabric or material can then be placed into an embroidery machine and mechanically embroidered. Many embroidery machines use multiple sets of hooped materials or fabrics in order to increase the speed, efficiency, and productivity of embroidery.
Hooping machines generally insert one ring of an embroidery hoop set into alignment with another ring corresponding to the hoop set. Hoops are common to the embroidery industry and hold fabric or other flexible material between them by friction of the two rings. The connected rings which hold the material or fabric between them can be attached to an embroidery machine.
2. Prior Art
Due to the mechanics of the hooping process, a pneumatic-operated hooping machine has proven to be a useful and efficient device, as opposed to mechanically operated models. The prior art teaches the use of a push plate which lowers hoops straight down onto corresponding hoops. Many hoop sets, however, cannot be readily meshed with a push plate lowering straight down onto a corresponding hoop. Irregular shaped hoop sets and larger hoop sets are particularly difficult to mesh using a straight downward approach.
The present invention teaches the use of a spring-loaded adjustable push plate which can initially lower one side of a first hoop into a second hoop, then cause the remainder of the first hoop to be lowered in the second hoop, following the contours of the second hoop.
Pneumatic hooping machines, however, can be dangerous due to the high pressures associated with pneumatic rams. The prior art has failed to successfully address and overcome the problems associated with the potentially serious injuries to hoopers fingers and other appendages. Fingers can readily become pinched between plates to be meshed. In light of the high pressures necessary to mesh hoop sets, there is a serious need for safety features associated with pneumatic rams.
The inventor has invented a pneumatic hooping machine which has a unique two-stage safety process protecting users of the pneumatic machine from seriously injuring a finger while using the machine. The novel safety system includes a two-way valve which can be activated by a low pneumatic pressure to combine with a high pneumatic pressure generating the force necessary to combine the inner and outer rings. The safety feature is connected to a foot operated pneumatic unit, providing both convenience and safety.
Other novel features of the invention include the many different modular parts which uniquely enhance the hooping experience. There are also many miscellaneous safety features associated with this new device.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the manner in which the above-recited other advantages and objects of the invention can be appreciated, a more particular description of the invention briefly described above will be rendered by reference to a number of specific embodiments which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not to be considered limiting in scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
FIG. 1 is a perspective view of the preferred embodiment of the present invention.
FIG. 2 features a front elevation of the preferred embodiment of the present invention.
FIG. 3 features a side elevation of the preferred embodiment of the present invention.
FIG. 4 features a top plan of the preferred embodiment of the present invention.
FIG. 5 features the ram of the preferred embodiment of the present invention comprising a pneumatic head, a safety feature, and an angle head. The angle head is featured in a horizontal or unangled state in FIG. 5.
FIGS. 6 and 7 feature the ram in the preferred embodiment of the invention from a view opposite that of FIG. 5. FIG. 6 features the angle head in a horizontal position while FIG. 7 features the angle head in an angled position.
FIG. 8 features a cross section of the safety mechanism employed in the preferred embodiment, comprising a cam and an actuating mechanism. The cam is in an upper position leaving the actuating mechanism in an unactuated state.
FIG. 9 features the cam in the preferred embodiment in a lower position, leaving the actuating mechanism in an actuated state.
FIG. 10 features a schematic of the preferred mechanism for retracting and extending the ram bar. The schematic is merely representative of the system of hoses, regulators, valves, manifolds, safety mechanism, and other parts used which comprise the mechanism for retracting and extending the ram bar.
FIG. 11 features a preferred push plate which is connected to lower plate of the angle head. The push plate receives and maintains a hoop to be placed on a corresponding hoop which rests on the hooping table.
FIG. 12 features an inner hoop connected to the push plate.
FIG. 13 features a hoop alignment mechanism connected to the upper surface of a hooping table.
FIG. 14 features a push plate which has been invented specifically for use with garments such as shirts and jackets which have a ring shape defining a hole through which wearers place their head and arms. The push plate is beveled and simulates the shape of a head and shoulders.
FIG. 15 features a locking mechanism which is typical of at least some of the locking mechanisms used on the preferred embodiment of the invention.
FIG. 16 features of cross section of a multilayered hoop alignment mechanism while FIG. 17 features a cross section of a multilayered hoop alignment mechanism with an outer hoop placed in the top layer.
FIG. 18 features a cross section of an angle head in the horizontal position. In this position the angle head is flush with the hooping table.
FIG. 19 features a cross section of an angle head in the angled position.
BRIEF SUMMARY AND OBJECTS OF THE INVENTION
The objects of the present invention are:
1. To create a hooping machine operated by pneumatic devices.
2. To create a pneumatic hooping machine wherein the pneumatic machines are run by a spring loaded foot driven pedal.
3. To create a pneumatic hooping machine wherein different speeds of pneumatic pressure are used in combination to create a pressure system which both operates the hooping function and features a safety mechanism.
4. To create a pneumatic hooping machine featuring a push plate connected to an angle head whereby a first hooping ring is initially pushed into alignment with a portion of the second ring and is then pushed into alignment with the remainder of the ring.
5. To create a pneumatic hooping machine which features a variety of interchangeable parts which can be modulated.
6. To create a pneumatic hooping machine featuring a non-rotatable pneumatic cylinder.
7. To create a pneumatic hooping machine featuring an automatic oiling system and a system for collecting the oil after oil and air are exhausted.
8. To create hooping tables which fit various kinds of material or garments and are supported by members which fit in with the hooping table and do not tear, rip, or mangle garments when garments are placed on the hooping table.
9. To create a pneumatic hooping machine featuring a guidance device for the accurate placement of articles or fabrics on the hooping table.
10. To create a pneumatic hooping machine in which the ram, the pneumatic cylinder, the horizontal member, the vertical member, the hooping table, and the arm containing the guidance device are adjustable, replaceable, and modulatable.
11. To create a pneumatic hooping machine comprising convenient side tables and arms for placing articles of clothing, binding fabric, and/or hoops on while working on the machine.
12. To create a check valve system wherein a high pressure is sent through a regulator creating a high pressure and a low pressure and the high pressure is preventing from returning through the check valve.
13. To create a pneumatic hooping machine wherein various kinds of push plates can be used in conjunction with various kinds of alignment rings which can in turn be used in combination with various kinds of hooping tables.
14. To create a pneumatic hooping machine which can be used in combination with various push plate attachments for holding an inner hoop in place until the inner hoop is combined with the outer hoop.
15. To create a pneumatic hooping machine featuring an angle-head which is spring loaded.
As the ram bar is extended towards the hooping table with a lower, safer air pressure, a cam actuates a valve assembly, sending a higher air pressure to the ram. The cam and valve mechanism is designed such that when the angle head meets with no interference, the safety mechanism allows a higher pressure to enter into the cylinder forcing the piston down at a high pressure and placing an inner ring into an outer ring resting in a hoop alignment mechanism. As the two hoops mesh, the flexible item between them is trapped by friction.
Another unique feature of the preferred embodiment of the machine includes that the hoop push plate has the ability to be moved to any location on the table that is being used, allowing for greater flexibility of locations and items to be hooped. Preferably, the push plate can be rotated 360° allowing hoops to be set at any rotation angle.
The other item setting this machine apart is the angle head. An angle head is particularly effective on larger or irregular shaped hoops. By employing the angle head, one end of the inner ring is inserted into the outer ring first. As the push plate travels closer to the table, the angle head springs are compressed causing the inner hoop to follow the edges of the outer hoop until the two hoops are brought into alignment. This allows for smoother insertion of the rings with less possibility of damage to items being hooped.
Because the machine is actuated by a foot valve, another unique item is the safety feature to keep hands from being seriously hurt. Because the ram is lowered with low pressure, anything preventing the travel of the ram will also prevent the actuation of the high pressure valve.
If the angle head meets an object, such as a finger, the low pressure continues pinching the object until the foot pedal is released. However, the actuating mechanism is not activated. Therefore, the high pressure system is not activated and the object is not seriously damaged. In the case of a finger, the finger may be pinched, but the air pressure can be adjusted so that the finger will not be broken. When the angle head meets with no resistance, the angle head continues into the alignment ring placing an inner ring into an outer ring and hooping a material or fabric.
The components in the most basic pneumatic hooping machine invented may be connected through a variety of devices. They may be welded together, or they may be connected through a variety of detachable mounting mechanisms. Furthermore, many other components may, and in the preferred embodiment are, added. One of the hallmarks of the preferred embodiment of the invention is its versatility and the ability of the user to interchange parts and to use or take off various parts as may be necessary under the circumstances.
The present invention describes a pneumatic hooping machine which features various devices which, in combination, act to create a unique, valuable, and highly marketable pneumatic hooping system. While the preferred embodiment contains many, if not each of the devices described, the most basic pneumatic hooping machine can be used without many of the devices disclosed.
The push plate is secured to the ram for receiving and maintaining a first hoop in a desired set position. A hooping table is mounted to the support frame, the hooping table being adapted to receive and maintain a second corresponding hoop in a desired set position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The pneumatic hooping machine is comprised of a horizontal floor member, known as a base plate 1, having a bottom side and an upper side, the bottom side of which rests on the floor and the upper side of which is mounted to a vertical support member 3. The vertical support member is comprised of a bottom end, a top end which may be and is preferably threaded with at least one thread (and most preferably one), and a middle portion.
The bottom end of the vertical support member 3 is mounted to the upper side of the base plate 1. One skilled in the art will recognize that the vertical support member may be mounted to the upper side of the base plate through a variety of mounting mechanisms. The vertical support member 3 may be welded or detachably mounted through a detachably mounted attachment mechanism.
For purposes of this specification, the term "mount" or "mounted" shall comprise various mechanisms through which components are connected, such as (1) welding the two components together, (2) detachably mounting the components through the use of a detachably mounted attachment mechanism, (3) soldering, and (4) other devices for mounting known in the art. Mounting mechanisms shall comprise welded edges of the components to be connected together, and detachably mounted attachment mechanisms. Detachably mounted attachment mechanisms shall be known as (1) brackets used in combination with nuts and bolts, screws or pins, (2) screws, (3) nuts and bolts, (4) pins, (5) roll pins, (6) clevace pins, (7) split pins, (8) joints, or many other detachable mounting mechanisms commonly used in the art.
The preferred mounting mechanisms connecting the vertical support member 3 to the base plate 1 comprise a support bracket 2 which is welded to a plurality of supporting base plate members 4 and is attached to the vertical support member 3 using a plurality of bolts inserted through ring-shaped portions of the a first side of one bracket defining a hole and through a corresponding ring-shaped portion of the vertical support member defining a hole and connected to a nut on the outside of a second support bracket, as shown in FIG. 1.
Throughout this entire specification and the appended claims, the word "proximal" shall mean closest to the vertical support member, while the word "distal" shall mean furthest away from the vertical support member.
To the middle portion of the vertical support member is mounted at least one outwardly extending horizontal table used for hooping and known as a hooping table 5. The hooping table is comprised of a lower face, an upper face, a distal end, and a proximal end. The distal end of the hooping table 5 is mounted on the vertical support member 3. It may be welded or detachably mounted and in the preferred embodiment is detachably mounted on the vertical support member by using a detachably mounted attachment mechanism 6. The detachably mounted attachment mechanism may comprise a variety of attachments which are commonly known to one skilled in the art, but preferably comprises a bracket opposite the vertical support member from the hooping table having a plurality of ring-shapes, each ring-shape defining a hole therethrough. Bolts are inserted through the ring-shapes into an internal nut within a framework 7 supporting the table.
Many different frameworks are possible. In the preferred embodiment, at least one upwardly extending hooping table support member, (and most preferably, three support members) is mounted, at its proximal end, below the hooping table to the vertical support member 3 and at its distal end to the framework 7. The hooping table 5, the framework 7 and the upwardly extending hooping table support members 8 are designed to allow a hooper to readily slide an article or fabric over them without tearing or ripping the fabric on the table, framework or support structures.
Many different tables can be used. The table 5, also shown in FIG. 14, is preferred for applications involving a head and shoulders portion of a garment or article. The table 5 may be used advantageously with garments such as shirts and jackets which have a ring shapes defining a hole therethrough which wearers place over their head and arms. The table 5 is beveled and simulates the shape of a head and shoulders. Thus, the table comprises a hooping table having a rounded, beveled protuberance in the distal end which tapers proximally in an asymmetric pattern, substantially simulating the pattern of a head and shoulders. The form fitting shape is specially contoured to such garments as T-Shirts and Sweatshirts which may be placed so that one side of the garment is over the table, ready to be hooped and the other side of the garment is under the table. Another possible table may be a thinner sleeve table, formed in a rectangular shape with a curved distal end.
In addition, an upwardly extending hooping table support member bracket 9 may be, and in the preferred embodiment is, employed so that a person can readily replace the table in use at a particular time without encountering difficulties in setting the height of the table, assuming a similar height frame is employed, and without readjusting the height of the ram 31.
Also in the preferred embodiment, additional components are attached to the vertical support member. For example, an accessory table 10, or preferably a plurality of accessory tables may be attached to the vertical support member, preferably supported by an accessory table support member 11 and upwardly extending accessory table support members 12, the accessory table support member being detachably mounted by using a detachably mounted attachment mechanism 13 in a horizontal position to the vertical support member, as shown in FIGS. 1-4. As many accessory tables as are necessary may be added, providing there is sufficient space for a hooper to stand near and operate the machine.
In addition, the preferred embodiment of the invention comprises at least one alignment arm 14 mounted detachably, at its proximal end, to the vertical column through the use of an guidance arm attachment mechanism, such as a detachably mounted attachment mechanism. The distal end of the arm comprises a plurality of gripping members 16.
The gripping members 16 hold a guidance device 17. By using a guidance device, articles of clothing or other fabrics which need to be embroidered in a uniform place in the garment or fabric can be mounted over the hooping table in a uniform position, guiding the hooper in placing the article in a uniform position in relation to the push plate 46.
The alignment arm 14, which preferably is comprised of three pivotable joints within the middle portion of the arm and one rotating joint located at the proximal end, can be adjusted to center a ray or beam of light onto a common landmark on the article or fabric, such as a zipper or a pocket corner. By centering at least one and preferably two guidance devices over at least one and preferably two landmarks in the transparent push plate and on the article of clothing or fabric, numerous articles of clothing can be placed in the same position on the hooping table, allowing a hooper to place the hoop in the same or essentially the same place on each article of clothing. This is particularly useful when using multiple hooped articles on automatic embroidery machines.
The preferred guidance device comprises a laser. Other guidance devices may comprise overhead projectors, flashlights, a light bulb, other sources of light known in the art, or other devices such as a wire or a scope.
A push plate 46 may, and in the preferred embodiment is used, and is preferably made of a transparent plastic (to shine a laser through), most preferably an acrylic sheet. The push plate 46 holds a first hoop 86 and pushes the first hoop 86 into alignment with a second hoop 18 which is resting in a hoop alignment mechanism 19, which may be and is preferably used in the present invention.
An outer hoop corresponds to an inner hoop, forming a hoop set. The two hoops are aligned or brought into alignment when the inner hoop is placed inside the outer hoop or the outer hoop is placed outside the inner hoop. When aligned, the inner hoop fits within the outer hoop and the article or fabric to be hooped rests within the two hoops. While an outer hoop may be placed on the push plate and lowered into an inner hoop, preferably, an inner hoop is placed on the push plate and lowered onto an outer hoop. Thus, the inner hoop preferably constitutes the first hoop 86.
The first hoop may be attached to the push plate through a variety of hoop securing devices, the devices comprising a screw, a spring loaded detente pin, a dowel pin, a magnet, double-sided tape, glue, a spring-loaded button, mounted onto a protuberance on the push plate which presses into an indentation in the hoop or hoop flange 97, or through a ring shaped member defining a hole in the hoop flange 97 or other securing devices.
Push plates existing in the prior art have been adapted to fit a single ring. In order to fit a certain ring, the push plate is beveled edges or a recess is cut fitting the contours of the hoop. These other push plates feature the use of a friction fit. In other words, prior art push plates are contoured to frictionally fit a single hooping ring; the shape of the push plate is molded around the hoop. Thus a new push plate must be used for each hoop.
One of the push plates invented by the inventor and disclosed in FIG. 11 can receive various kinds of hoops without having to use a new push plate. This unique feature is performed through the use of at least one and preferable two gripping members 85 and a securing device attached to the gripping member(s). Thus, rather than using a push plate which is molded to grip the hoop frictionally, the hoop is attached with a hooping flange holding pin 87, the pin comprising a screw, a spring loaded detente pin, a dowel pin, or a spring-loaded button which presses into an indentation in the hoop or hoop flange 97, or through a ring shaped member defining a hole in the hoop flange 97 or other securing device well known in the art.
The hooping flange holding pin 87 is preferably a missile shaped pin which is smaller on the bottom portion and is larger towards the top.
When using a high pressure source, such as a pneumatic ram, it is generally helpful and preferred to create a push plate which pushes, as much as possible, on the ring, rather than on the supporting flange structures 97 often accompanying rings. Placing the pressure on the ring, rather than the flange, prevents the ring or flange from splitting or breaking. In the most preferred mode, pressure from the push plate should be placed evenly on the ring and the supporting flange 97.
The gripping mechanism 85 is designed to attach to various kinds of supporting flanges. For example, the push plate gripping mechanism 85 may attach to the supporting flange 97 disclosed in FIG. 12 through the use of a hoop flange holding pin such as a dowel pin. Similarly, other holding pins may be used as is well known in the art.
Certain supporting flanges further comprise secondary flanges which closely fit into and extend upwardly into the contours of the push plate gripping mechanism 85 and the neighboring side of the push plate. Because the hoop flange holding pin 87 can extend both into flanges which do not closely hug the gripping mechanism and flanges 97 which do not tightly grip the walls of the push plate, as seen in FIG. 12, the push plate disclosed in FIG. 11 is a unique and novel contribution to the art.
The push plate disclosed can attach to rings comprising such secondary flanges, as well as rings not comprising such secondary flanges. Thus, the push plate disclosed in FIG. 12 is an example of a push plate which can be used with various hoops, rather than merely one hoop.
Another feature which is not necessary, but is within the preferred embodiment of the invention, is a hoop arm 20 comprising a proximal end connected to the vertical support member 3 by a hoop arm attachment mechanism and, at the distal end, a hoop arm lip 21. The hoop arm attachment mechanism may be comprised of a detachably mounted attachment mechanism. Using the lip 21, the hoop arm, which preferably is comprised of at least one rotating joint at its proximal end, may be used to conveniently hold items such as a hoop or hoops, or articles of clothing or pieces of fabric, or other supplies or equipment.
A rotatable accessory table 23 may, and in the preferred embodiment is used. The distal end of a rotatable accessory table support member 24 is connected to the table while the proximal end of the rotatable accessory table support member 24 is detachably connected to the vertical support member 3 through the use of a rotatable accessory table support member clamp (a single proximal rotating joint) 25, which may comprise a detachably mounted attachment mechanism. The clamp 25 connects to the vertical support member and connects to a rotating joint which connects to the rotatable accessory table support member 24.
A horizontal beam 26 is disclosed, comprising a distal end, a middle portion and a proximal end. The under side of the proximal end preferably defines a hollow recess and is preferably threaded with a plurality of threads, most preferably two. The horizontal beam is attached at its proximal end to the top end of the vertical column, preferably by threading at least one thread on the vertical support member into the plurality of threads on the horizontal beam, forming a first swivel joint 29.
The first swivel joint 29 may, and in the preferred embodiment does, allow the horizontal beam 26 to swivel at least 180°. A locking mechanism 30 may be, and preferably is, attached to the first swivel joint 29 preventing the first swivel joint 29 from moving during the use of the machine.
A pneumatic ram 31 is disclosed, comprising a top end, a middle portion and a bottom end. The ram 31 may be mounted at its top end to the distal end or middle portion of the horizontal member 26, as may be necessary, depending upon the article to be hooped. The ram 31 may be attached to the horizontal member through welding or through a detachably mounted attachment mechanism.
In the preferred embodiment, the ram is attached to the horizontal member through the use of a collar 32, the collar 32 comprising an inner portion, an outer portion, an a lower threaded surface 34. The inner portion of the collar slidably surrounds the horizontal member 26 having the ability to slide from the proximal end of the horizontal member to the distal end of the horizontal member.
Preferably, the collar 32 contains a collar locking mechanism, known as a first locking mechanism, 33 to prevent the sliding of the collar 32 during the operation of the machine. The upper surface of the ram 31 may be attached to the lower threaded surface 34 of the collar 32 if threads are welded into the upper surface of the ram, allowing the ram to rotate 360° on the threads.
The lower threaded surface of the collar 34 may, and preferably does, comprise a lower threaded surface locking mechanism, known as a second locking mechanism, 35, shown in FIG. 15, to prevent movement of the ram 31 during operation of the machine.
The locking mechanism which may be used in multiple places on the machine in various embodiments is shown in FIG. 15 and comprises a compression locking bar 106, which compresses a joint, flange, thread, or series of threads, and preventing movement of the joint, flange, thread, or set of threads. A plurality of protrusions exist on a split member 108, such as the lower threaded surface 34 of the collar 32, which has a recess defining a slit 110 between one edge of the collar and another edge. One protrusion 107 exists on each side of the slit. The protrusions have corresponding ring shapes defining holes therethrough, through which the locking bar 106 is inserted. When the locking bar 106 reaches an external nut 109, the locking bar is threadably inserted into the nut 109. Gripping flanges 113 extending from the nut prevent the rotation of the nut after the gripping flanges 113 are lodged through rotation of the locking bar 106 against a protrusion 107.
The use of gripping flanges 113 on an external nut 109 is preferred on this invention to an internal nut because the nut may be turned an initial amount, no more than 180°, without turning the locking bar 106. This is advantageous because the many components on the machine often make it difficult to turn the locking bar 106, preventing rotation of the locking bar more than a slight distance.
The use of the collar 32, the first swivel joint 29 and the threaded surface 34 allows the ram to be moved, rotated and locked into many different places over the hooping table 5 and otherwise within the working area, increasing ease and flexibility of use.
The pneumatic ram 31 preferably comprises a non-rotating pneumatic bar 36. A rotating pneumatic bar is useful, particular if perfectly circular hoops are used. However, particularly when non-circular hoops are used, such as rectangular shaped hoops, a rotating bar may tend to rotate during the depression of the bar and before a first hoop 86 is joined with a second hoop 18, throwing the hoops out of alignment.
Thus, a ram comprising a single ram bar may be used without rotation if a device is used to prevent the single ram bar from rotating. A double ram bar 36 shown in FIG. 9 extended from the cylinder housing 76 is preferred because of its non-rotating features. Mounted to the bottom end of at least one ram bar is a mounting block 37, comprising a top and bottom end. An example of a preferred ram is the Non Rotating Rod Air Cylinder, Speed Aire, W. W. Granger, Lincolnshire, Ill.
In the preferred embodiment, the bottom end of the mounting block 37 is connected to an angle head 38, comprising a first plate 39 connected by its upper surface to the bottom end of the mounting block 37, a second plate 40, a hinge 41 connecting the top and bottom angle head plates at a front end, and a spring loading mechanism for spring loading the two plates 42 located near the rear end.
The first hoop may be attached to the bottom surface of this second plate 40 through a variety of hoop securing devices. The second plate thus becomes another embodiment of a push plate. However, connection of the hoop directly to the first plate is not preferred because of the transparent nature of the push plate and the hoop securing devices on the push plate. The top surface of the push plate 46 is preferably attached directly to this second plate 40.
The preferred spring loading mechanism 42 comprises at least one coil spring and most preferably, a plurality of coil springs. Other mechanisms include another small pneumatic ram, torsion springs, and extension springs.
The spring may, and preferably does, rest upon a spring seat member 93. Furthermore, the first plate 39 may, and preferably does comprise a spring tower 94 in which the spring loading mechanism 42 is compressed when the angle head 38 is completely lowered. Upon locking the second plate 40 to the first plate 39 or, alternatively, upon complete extension of the ram bar 36, the second plate 40 becomes flush with the first plate 39 and the spring loading mechanism 42 is compressed within the spring tower 94.
In the preferred embodiment, at least one side panel 43 (and most preferably two side panels 43) is mounted perpendicularly on the second plate 40, shielding the hooper from catching a finger or other appendage between the first plate and the second plate during operation of the machine. A rear panel 95 shields the areas surrounding the rear portion 96 of the angle head.
A stop 45 having a ring-shape and defining a hole therethrough may be comprised within the second plate 40. By inserting an angle head bolt 44 through the stop and into a nut, preferably an internal nut located inside the first plate 39, the range of motion of the spring loading mechanism can be reduced to a range pursuant to which the rear panel 95 covers the rear end of the first plate 96 at all times during the operation of the machine, preventing the operator from lodging a finger or other appendage between the rear panel 95 and bottom side of the first plate.
The safe, spring loaded, angle head 38 makes it possible for the first hoop 86, detachably mounted to the push plate 46, the upper surface of which is connected to the lower surface of the second plate 40, to contact the second hoop at an angle then flatten out as the angle head spring loading mechanism is compressed. The final result is that the first and second plates are flush to each other and flush to the table when the ram bar 36 is extended to its lowest position.
The angle head bolt 44 can also lock the angle head 38 into a position which is flush with the hooping table 5 and perpendicular to the vertical support member by pressing the second plate 40 into a position flush with the first plate 39 and tightening the angle head bolt 44, as is demonstrated in FIG. 6. Thus, the angle head may be lowered at a position which is flush with the hooping table, that is, parallel to the hooping table and perpendicular to the vertical support member.
In the alternative, the angle head may be lowered at an angle. When the angle head bolt is loose enough to allow the stop 45 to rotate or move, as in FIG. 7, the angle head can be lowered at an angle, as shown in FIG. 7, and the second plate then becomes flush with the hooping table when the angle head is fully lowered and the first hoop 86 is aligned with the second hoop 18.
Although the pneumatic hooping machine can be used without the angle head, i.e. through the use of a first plate connected to a push plate or a first plate connected directly to a first hoop, without the angle head, the first hoop must be lowered horizontally, which is less advantageous, particularly for irregular shaped hoops which are difficult to align with a corresponding hoop.
By using the angle head, shown in FIG. 7, the inner hoop may be initially lowered into a portion of the outer hoop, then lowered into the remainder of the outer hoop as the angle head is compressed, allowing the hooper to hoop with irregular shaped hoops.
Preferably, connected to the second plate 40 of the angle head 38 through the use of a push plate attachment mechanism, such as bolts, is the push plate 46. The preferred push plate 46 is equipped with internal threads in its upper surface, allowing one to bolt the push plate onto the second plate 40. The preferred first plate has four ring-shapes defining holes therethrough allowing the bolt heads connected to the second plate to rise through the holes in the first plate without preventing the first plate from becoming flush with the second plate when the angle head is compressed.
By using the moveable joints, swivels, and attachments described, the first hoop can be aligned while the second hoop is at any place on the table. The second hoop 18 may be resting on the hooping table 5 during the operation of the machine, but is preferably placed in a hoop alignment mechanism 22 which is attached to the table through the use of a variety of hoop alignment mechanism attachment devices, comprising a screw, a spring-loaded detente, a magnet, double-sided tape, glue, a spring-loaded button, a screw, a spring-loaded detente pin, or other devices. Two-sided tape is preferred as an attachment device because of the frequent changing of hoop alignment mechanisms, but other possible hoop alignment mechanism attachment devices include glue, screws, nuts and bolts, and other attachment devices which are well known in the art.
A hoop alignment mechanism constitutes a mechanism on the hooping table for readily holding a hoop in a set position on the table in preparation for precision alignment with a corresponding hoop. Various kinds of hoop alignment mechanisms are available. Many must be tailored to the hoop to be used. One feature relating to hoop alignment mechanisms invented by the inventor which can be used generically among with almost all hoop alignment mechanisms is a multilayered hoop alignment mechanism.
FIGS. 16 and 17 demonstrate an example of the multilayered hoop alignment mechanism in cross section. The lower edge 112, which is closer to the hooping table than the upper edge 111, runs throughout the inner surface of the hoop alignment mechanism, except where a notch 115 is made for removing the outer ring or for receiving a ring connection joint 114.
The lower edge 112 of the multilayered hoop alignment mechanism is useful, particularly when hooping thick materials such as sweatshirts. Hooping rings are the most effective at holding clothing or other material when then there is the greatest amount of friction between the rings, i.e. when the inner and outer ring are in perfect alignment.
When an outer hoop rests directly on the hooping table in a single-layered hoop alignment mechanism, and a backing fabric and the material to be hooped are layed over the hoop, the inner hoop is often prevented from coming into perfect alignment with the outer hoop because the material resting on the table prevents the inner hoop from going all the way down to the table, which is necessary to for the inner hoop to reach perfect alignment with an outer hoop resting on the table. The height of the backing fabric and material prevents the inner hoop from reaching perfect alignment with the outer hoop.
By using a multilayered hoop alignment mechanism, the innacuracy caused by single layered hoops is adjusted for. The backing fabric and material are compressed onto the hooping table, but the inner hoop does not need to proceed down to the hooping table because the outer hoop has been raised from the hooping table. The height of the edge 112 on which the outer hoop rests is determined by the height of the fabric to be hooped plus the height of backing fabric.
The multi-layered effect may be achieved by using a hoop alignment mechanism with two built-in layers or by using a hoop alignment mechanism with a single layer in combination with a detachable inner layer. A built in layer system is preferred for convenience of use.
When thin materials are to be hooped, such as t-shirts, the innacuracy caused by the placement of the outer hoop on the hooping table is negligible. However, when heavy materials such as sweatshirts are hooped, a hooper may be required to manually push the inner ring into perfect alignment with the outer ring--even after a hooping machine has been used.
Manual alignment of the hoops may contribute to fatigue and possibly injury. The use of multiple layers allows the person using a hooping machine to accurately align the inner hoop with the outer hoop, hooping heavy materials, without such extreme factors of fatigue and injury.
The hoop alignment mechanism 19 may be placed in many different places on the hooping table, depending on the article or garment to be hooped. Often it is desireable to place backing fabric over the hoop alignment mechanism before the second hoop is placed in the hoop alignment mechanism. The purpose of the backing fabric is to lend stability to the embroidery, as is well known in the art.
However, often when backing fabric is placed over the hoop alignment mechanism without being secured, and a garment or other article is placed over the hooping table, the backing fabric is often swept away from the hoop alignment mechanism by the garment.
To prevent this problem, the preferred hoop alignment mechanism employs a spring loaded backing attachment mechanism 84, which may, for example, comprise clips. The backing fabric is placed into the clips before the article is placed over the hooping table. Upon placing the garment over the hooping table, the backing fabric is held in place by the spring loaded backing attachment mechanism 84.
The piston 67 within the ram, the lower side of which is connected to the top side of at least one ram bar, is held in a retracted state within the cylinder housing 76 through the use of an air source originating initially in an air supply source 61. FIG. 8 demonstrates the view of the ram 31 when the piston 67 is in a retracted state. FIG. 9 demonstrates the view of the ram when the piston 67 is in an extended state.
FIG. 5 demonstrates the placement of the safety mechanism 47 on the bottom portion of the ram 31, which comprises a unique hallmark which may be and in the preferred embodiment is used in association with the present invention.
FIGS. 8 and 9 demonstrate the safety mechanism 47 in cross section. The safety mechanism 47 allows a hooper to lower the first hoop onto the second hoop using a powerful pneumatic ram with a safety mechanism, preventing injuries to fingers and other appendages.
The safety mechanism is comprised of a valve body 55, comprised of, for example, a two way valve, to which is attached a valve actuation arm 53. At the end of the valve actuation arm most distal to the valve body 55 is attached a valve actuation roller 52, while an arm pivot 54 is attached to the valve body 55 at the end of the actuation arm 53 most proximal to the valve body 55. An actuation button 92 is attached to the valve body 55 under the actuation arm 53, and is actuated by the movement of the actuation arm toward the valve body. FIG. 8 demonstrates the safety mechanism in the unactuated state, while FIG. 9 demonstrates the safety mechanism in the actuated state.
The MV2-C Roller Leaf, for example, sold by "air-mite," Chicago, Ill., is comprised of a two-way valve body, arm pivot, valve actuation arm, valve actuation roller, and an actuation button and works well in combination with the other features of the present invention.
In the preferred embodiment, the safety mechanism which may comprise and preferably comprises a safety housing 56 which wraps around the essential components of the safety mechanism in a U shaped members. The safety housing 56 is connected to the lower portion of the ram 31 through the use of a safety mechanism attachment member comprising a front 102 and a side 105. The safety mechanism attachment member is preferably comprised of a bracket mounted on the ram through the use of a detachably mounted mounting mechanism. Preferably at least one and most preferably two bolts 104 bolt through ring shapes which define holes in the bracket into internal nuts in the ram. The preferred bracket is a bracket stretches over two sides of the of the four sided ram, has a 90° angle, and is slotted with ring shaped members defining holes for adjustment up and down the ram. The safety mechanism attachment member could also comprise a mounting mechanism, such as welded edges, screws, bolts, pins, or other devices commonly known in the art.
The safety mechanism 47 is mounted on the side of the safety mechanism attachment member 105 through the use of a mounting mechanism, preferably comprising two screws which screw through ring shapes defining holes in the safety housing 56, through ring shapes defining holes in the valve body, through ring shapes defining holes in opposite side of the safety housing 56 and into external nuts on the outside of the safety housing. Other mounting mechanisms are possible to mount the safety housing 56 to the ram 31, such as welding, soldering, screws, nuts and bolts, and the use of various pins.
The idler roller 51 is held in place through the use of a screw extending through a ring shape in the safety housing defining a hole, through a ring shape in the idler roller defining a hole, through another ring shape in the opposite side of the safety housing defining a hole, into an external lock nut. Pins and screws and other mounting mechanisms would also be available to mount the idler roller.
In the present invention, the lower end of a cam 48 is attached to the first plate 39 through the use of a cam attachment mechanism 98, such as a mounting mechanism. Preferably, the cam attachment mechanism is comprised of at least a first raised protuberance 89, and in the preferred embodiment, a plurality of raised protuberances, extending upwardly from the first plate 39. Component 90 is an example of a second raised protuberance. Furthermore, in the preferred embodiment, the lower end of the cam 48 has a ring-shape defining a hole therethrough 91, through which a screw is threaded. The screw is also threaded through the protuberances 89, 90 and is secured with a nut. In the most preferred embodiment, the screw is loosely threaded and the cam's ring-shape defining a hole which is large enough to allow for some play between the ring shape and the screw.
By being loosely engaged, the cam prevents false openings. The hinge pin is not welded solid to first plate because such a rigid attachment could cause unintended actuations of the actuation button 92. By having the cam pivot, it floats downward rather than being rigid, opening only when the ram is extended to the desired position.
When the first plate 39 is lowered, the secured cam is lowered, stabilized by the idler roller 51. When the cam 48 is lowered, as in FIG. 9, to a point in which the widened cam flange 99 contacts the valve actuation roller 52, the valve is actuated allowing a gas, such as air, to flow from the two-way valve intake port elbow 58, which threads into internal threads in the two-way valve intake port, through the two way valve outlet port which has internal threads and into which is threaded the two-way valve outlet port elbow 50, allowing high pressure gas to flow through the two-way valve into the pneumatic cylinder 100, forcing the piston into an extended position using high pressure gas and lowering the angle head 38 the full distance needed to align the first and second hoop.
Thus, lowering the angle head 38 a certain distance, using pneumatic pressure or other pressure mechanisms, activates the lowering of the angle head to a greater distance. In the event the widened cam flange 99 is prevented from reaching the valve actuation roller, the high pressure gas is not emitted into the pneumatic cylinder 100, and the angle head 38 does not proceed downwardly at a high pressure. Instead a low pressure force continues.
Thus if an object, such as a finger is trapped between the hoop alignment mechanism 19 and the push plate, preventing the widened cam flange 99 from reaching the valve actuation roller 52, only low pressure gas is applied against the finger.
The use of the safety mechanism 47 in combination with a pneumatic ram is a significant and innovative contribution to the art. The many other safety and functional mechanisms associated with the pneumatic ram provide for a safe, powerful and effective means to hoop articles of manufacture.
In the most preferred embodiment, the safety mechanism 47 is provided with an false actuation prevention device 88. The false actuation prevention device prevents the cam shaft 103 from actuating the actuating button by striking the valve actuation roller 52 with the cam shaft when the shaft is moved or toggled. The false actuation prevention device is strategically located to the block the cam shaft 103 from striking the valve actuation roller 52 until the widened cam flange 99 reaches the valve actuation roller 52.
The false actuation prevention device is preferably comprised of a piece of steel and is connected to the safety housing through the use of a mounting mechanism. The preferred mounting mechanism is a welding of the two edges of the piece of steel onto opposite sides of the safety housing, forming a bridge between the two sides. The false actuation prevention device could also comprise a bolt, screw or pin mounted to both sides of the U shaped safety housing, forming a bridge. The false actuation device is an example of a means for preventing the false actuation of the high pressure valve system when the cam shaft is toggled.
One skilled in the art will recognize that there are many different means for retracting and extending the ram bar. The following discloses the preferred means for retracting and extending the ram bar using a system of pneumatic hoses and regulators.
In order to control the angle head without a hooper having to use at least one of his hands, a spring loaded foot pedal 60, attaching to a four way valve manifold system 83 is provided. Safety may be further enhanced by the provision of a foot pedal cover 59. The foot pedal is mounted to the base plate through the use of a mounting mechanism, preferably three bolts bolted to the base plate.
When the spring loaded foot pedal 60 is left in the elevated state, compressed gas, such as air, is provided from a supply inlet 61 through a regulator 62, through an automatic lubrication system 63 to the supply port 64 of a manifold 83, comprised of a four way valve, through a cylinder port retraction line 65 into a ram retraction port, 66 forcing the piston into a retracted state and consequently forcing the angle head into the up position as shown in FIG. 8.
When the foot pedal is depressed, the gas coming into the manifold 83 is routed through a cylinder port extension line 69 to a first T 70 which separates the air into two main extension lines.
The air in the first extension line 71 passes through a second regulator 72 which reduces the pressure. In the most preferred embodiment the pressure is reduced to approximately 20 pounds per square inch. The air in this first extension line then passes through a check valve 73, then continues to second T 74 and through the extension port 75 into the pneumatic cylinder 100, extending the piston, lowering the angle head, along with the cam 48. The air in the second extension line 77 passes through an elbow joint 49 into the two-way intake port, where it is prevented from progressing unless the actuation button 92 is actuated. If the widened cam flange 99 depresses the valve actuation roller 52, actuating the actuation button 92, high pressure gas flows through the two-way valve intake port elbow 58 which threads into internal threads in the two-way valve intake port, through the two-way valve exit port into which an elbow 50 is threaded and into the third extension line 78, into the second T 74, and eventually into the cylinder 100, extending the piston 67, and as a result, the angle head 38 with high pressure. The check valve 73, prevents the loss of high pressure air into the portion of the first extension line 71 preceding the check valve 73.
Depression of the foot petal also exhausts air through the ram retraction port 66, through the cylinder port retraction line 65, through the first manifold exit exhaust port 68, through the fourth T 82, through the third T 80 and into the canister 81 comprising an air muffler and an oil catcher.
When the foot pedal is released, the foot pedal raises to its up position, and air is exhausted through the two-way valve exhaust port elbow which threads into internal threads in the two-way valve exhaust port 57, into the extension line exhaust 79, through the third T 80 and into a canister 81 comprising an air muffler and an oil catcher. Air is also exhausted through the first extension line 71, into the cylinder port extension line 69, through the manifold exit exhaust port 101, through the fourth T 82, through the third T 80, and into the canister 81.
One skilled in the art will note that the ranges of the low and high pressures are determined by a number of factors including the fabric to be hooped, the parts used, the ram employed, the regulators used, and what pressures the parts are rated for.
The combination of the cam 48 and the valve body 55 thus comprise a means activated by the low pressure for activating the higher pressure unless the lower pressure meets with resistance.
The lowest range of the low pressure is determined essentially by the pressure necessary to make the widened cam flange come in contact with the valve actuation roller and the speed desired for the movement of the ram bar from the retracted position to the extended position. The highest range of the low pressure is whatever pressure will allow the fastest movement of the ram bar without significantly damaging fingers or other appendages which may become caught between the first ring and the second ring. When using the Speed Aire Non Rotating Rod Air Cylinder, the range of the low pressure desired in the hoses after the second regulator 72 is preferably approximately 5 p.s.i. to approximately 40 p.s.i., with 20 p.s.i. as a most preferred range. These ranges are not limiting upon the scope of the invention because the actual ranges to be considered are the pressures necessary to extend the ram bar (or preferably ram bars), yet not significantly injure an appendage.
The lowest range of the high pressure is determined by what pressure is necessary to press an inner hoop and outer hoop into alignment. The highest range of the high pressure is determined by the highest pressure for which the components in the pneumatic system such as the regulators, the check valve, the four way and two way valves, and the ram are rated for. The high pressure should not exceed what these parts are rated for.
In addition, the high pressure should not exceed what the fabric or material to be hooped can withstand. Many fabrics, such as cottons, as susceptible to hoop burn if too high of pressures are employed in hooping. Other fabrics, such as nylon may withstand greater pressures without damage. When cottons are hooped, a pressure between approximately 50 to approximately 250 p.s.i. is the pressure on the push plate which is preferred. The amount of pressure on the push plate is determined by the amount of pressure in the pneumatic hose system and the ram used.
When using the Speed Aire Non Rotating Rod Air Cylinder, pressures between approximately 45 p.s.i. to approximately 150 p.s.i. are contemplated as being suitable as the pressure to be used after the air passes the first regulator 62 and the first T 70. The preferred ranges of high pressure are 80 to 120 p.s.i. with 80 p.s.i. being the most preferred for high pressure when cotton fabrics are hooped. However, these ranges are not limiting upon the scope of the invention because the actual ranges to be considered are factors of the equipment used, the ram used, and the fabric to be hooped.
While a pneumatic system is the preferred system for operating the machine, since the system of hoses and valves used to operate the machine is the same as or substantially similar to a system to be used in operating a hydraulic cylinder, one could readily convert this machine to a hydraulic hooping machine, employing a hydraulic cylinder rather than a pneumatic cylinder, yet still comprising the machine's unique safety mechanism, angle head and/or modulatable tables and guidance devices.
One skilled in the art will recognize that a push plate is secured to the ram for receiving and maintaining a first hoop in a desired set position, the first hoop defining a plane and a hooping table is mounted to the support frame, the hooping table being adapted to receive and maintain a corresponding second hoop in a desired set position, the second hoop defining a plane.
The angle head includes offsetting plates for maintaining the plane of the second hoop in an intersecting relationship with the plane of the first hoop.
One skilled in the art could also readily would the preferred embodiment of this invention into an electric hooping machine or a mechanically driven hooping machine. The machine's unique features such as the safety mechanism, angle head and/or modulatable tables and hoop alignment mechanism could be used in conjunction with many different means for extending and retracting the ram and as a result, the push plate. The push plate could be lowered and raised mechanically, electrically, through gas driven mechanisms, or through other devices to extend the bar on which the mounting block or first plate is mounted.
One skilled in the art will readily recognize that reference to the safety mechanism 47 refers to a safety means activated by the low pressure which activates the high pressure unless the lower pressure meets with resistance.
Furthermore, while the specification often refers to air as the gas to be used in the pneumatic hooping machine, this characterization is not to be limiting. Gases which may be used in the system comprise compressed air, nitrogen, argon, helium, and other inert gases.
Finally, the disclosure of the machine as a hooping machine is not intended to limit its use to meshing hoops together. The machine is useful for combining any items which must be meshed or aligned. Thus, the machine has applications such as the silk screen industry in which screens must be meshed.
The use of the term inner hoop is considered to be synonymous with the phrase male hoop while female hoop is considered to refer to the outer hoop.
The invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all resects only as illustrative and not as restrictive. The scope of the invention is, therefore, to be indicated by the appended claims rather than by the foregoing descrition. All changes which come within the meaning and scope of the claims are to be embraced within their scope.
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A safe, efficient hooping machine preferably driven by pneumatic power comprising an adjustable hoop push plate, an angle head which is for inserting an inner ring into an outer ring and a safety feature which allows hoopers to keep their hands from becoming seriously hurt when a hooping ram is lowered.
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BACKGROUND OF THE INVENTION
[0001] 1. The Field of the Invention
[0002] This invention relates to a radial copolymer prepared from a conjugated diene monomer and a vinyl aromatic monomer. More specifically, the present invention relates to a radial copolymer useful for the manufacture of tires that has its molecular chain terminal coupled using a mixed coupling agent comprised of a mixture of multi-reactive polysiloxane and tin halide.
[0003] 2. Related Prior Art
[0004] Conjugated diene polymers prepared using an organo lithium catalyst are controllable in regard to the vinyl content of the conjugated diene that cannot be controlled by the emulsion polymerization method, so that they are excellent in both wet traction and rolling resistance relative to the styrene-butadiene rubber (SBR) prepared by emulsion polymerization. If synthesized in the presence of an organo lithium catalyst, the polymer has multiple functional groups at the molecular chain terminal that make the cold flow controllable at the ambient temperature and particularly enhance the compatibility with a reinforcing material for tires, such as carbon black or silica, thereby enhancing treadwear, reducing rolling resistance and increasing wet traction.
[0005] When the molecular chain terminal of the copolymer prepared by solution polymerization in the presence of an organo lithium catalyst is substituted using a tin coupling agent, the above-mentioned effects can be achieved in the carbon black mixed rubbers because the tin compound has a high compatibility with the carbon black. But, the use of the tin compound as a coupling agent may lead to a low binding capacity (Sn—C bonding) between the tin compound and the rubber, so that the Sn—C bonding can be broken under the physical force during the mixing step, thereby deteriorating mechanical properties of the rubber. For that reason, the use of tin-coupled rubber is restrained in the manufacture of silica-mixed rubber tires of which the processing conditions are much stricter than those of the carbon black mixed rubbers (U.S. Pat. No. 4,397,994).
[0006] On the other hand, an approach to enhance the compatibility of the rubber with carbon black involves conversion of the molecular chain terminal to benzophenone, which is a sort of amine compounds, attaining more excellent dynamic characteristics and mechanical properties than the existing rubber materials. The rubbers prepared by this method are, however, inferior in processability during the mixing step and long-term storage due to its high cold flow that is as a key factor of storage stability (U.S. Pat. Nos. 4,555,548 and 5,219,945).
[0007] For examples of the approach for increasing the compatibility with silica used as an inorganic reinforcing material disclose a method of dispersing polydimethylsiloxane in a styrene-based resin composition to enhance tread wear and cold impact resistance remarkably. But the polymer complex prepared by dispersion of polydimethylsiloxane is susceptible to phase separation because it has no covalent bond between the polydimethylsiloxane and the organic polymer resin. Moreover, they are inferior in affinity to inorganic fillers, causing a deterioration of the compatibility, because the polydimethyl siloxane contains neither polar groups nor hydrophilic groups.
[0008] Accordingly, the modification of polymers that are organic materials ready for reactions is necessary in the improvement of mutual compatibility for the purpose of developing the above-described organic and inorganic composite material. So, many studies have been made on the modification of polymers using physical methods. For example, it discloses a polymerization of hexamethylcyclotrisiloxane at the terminal of the living polymer block. This approach may solve the problem with the organic separation of polysiloxane from the organic layer, but results in a low affinity to organic fillers and hence a deterioration of the compatibility as in the above-stated technologies, because the polydimethylsiloxane has no functional group including a polar group or a hydrophilic group.
[0009] To solve this problem, there are some cases where the living anionic polymer terminal is reacted with ethylene oxide (J. Polym. Sci., Part A: Polym. Chem., 26, 2031 (1988)); diphenylethylene (J. Polm. Sci., Part A: Polym. Chem., 30, 2349 (1992)); or N-(benzylidene)-trimethylsilylamine (Makromol. Chem., 184, 1355 (1983)), which compounds contain no siloxane group and are limited in acquiring a satisfactory compatibility with inorganic fillers.
[0010] Accordingly, there is a demand for polymers containing polar groups and using a novel coupling agent susceptible to reaction with a living polymer anion.
[0011] Another approach has been suggested that acquires enhanced properties in carbon black mixing by using the mixture of tin halide and silicon halide as a coupling agent for the terminal of the polymer (U.S. Pat. No. 6,329,467 B1). The coupling agent contains no functional group having the affinity to silica, deteriorating the compatibility of the polymer with silica. So the use of the coupling agent is restrained in the manufacture of silica-mixed rubber tires.
SUMMARY OF THE INVENTION
[0012] In an attempt to develop rubbers having an improved compatibility with silica, an affinity to carbon black, and an excellent processibility in the manufacture of tires, the present invention has been contrived on the basis of the fact that the rubber for tires with enhanced mechanical properties and dynamic properties (e.g., wet traction and rolling resistance) relative to the conventional rubbers can be provided by modifying the terminal of the rubber using a mixture of a polysiloxane compound having a high affinity to an inorganic material, silica and a tin halide compound having a good processibility with carbon black.
[0013] It is therefore an object of the present invention to provide a radial copolymer for enhancing the mechanical properties and the dynamic properties of a silica-carbon black mixed rubber for tires relative to the conventional rubber materials.
[0014] To achieve the object of the present invention, there is provided a radial copolymer prepared by coupling the terminal of a living polymer using a mixed coupling agent comprising a mixture of a multi-reactive polysiloxane represented by the following formula 1 and a tin halide represented by the following formula 2, the living polymer being prepared by copolymerizing a conjugated diene monomer and a vinyl aromatic monomer in the presence of an organo lithium catalyst in a hydrocarbon solvent and a Lewis base:
(X) a (R) b Y—(CH 2 ) c —Si(R 1 )(R 2 )—[O—Si(R 1 )(R 2 )]d—(CH 2 ) c —Y(X)a(R) b Formula 1
[0015] where X is a halogen atom such as F, Cl, Br or I; Y is Si or C; R is a lower alkyl group containing less than 20 carbon atoms, such as methyl, ethyl or propyl, or (X) e (R 3 ) f Bz; R 1 and R 2 are the same as R, hydrogen, halogen-substituted alkyl group, or halogen-substituted silane group; R 3 is a lower alkyl group containing less than 20 carbon atoms, hydrogen, halogen-substituted alkyl group, or halogen-substituted silane group; a is 1 to 3, and b is 0 to 2, wherein a+b=3; c is 1 to 10; d is 1 to 100; e and f are independently 0 to 5, where e+f=5; and Bz is a benzene ring;
Sn(R) 4−n (X) n Formula 2
[0016] where R is a lower alkyl group containing less than 20 carbon atoms, such as methyl, ethyl or propyl; X is a halogen atom such as F, Cl, Br or I; and n is an integer from 1 to 3.
[0017] The present invention will now be described in further detail as follows.
[0018] The copolymer of the present invention is prepared from a conjugated diene monomer and a vinyl aromatic monomer. The specific examples of the conjugated diene monomer as used herein may include butadiene or isoprene compounds, and those of the vinyl aromatic monomer as used herein may include styrene or α-methyl styrene.
[0019] Typically, the copolymer comprises 5 to 50 wt. % of the vinyl aromatic compound, and 50 to 95 wt. % of the conjugated diene compound. If the content of the styrene compound is less than 5 wt. %, then neither tread wear nor wet traction can be enhanced; otherwise, if the content of the styrene compound exceeds 5 wt. %, then neither tread wear nor exothermic characteristic can be enhanced.
[0020] The copolymer of the present invention is prepared by copolymerizing the monomers in the presence of an organo lithium catalyst in a hydrocarbon solvent to yield a living polymer, and then coupling the living polymer to a molecular chain terminal using a coupling agent. The specific examples of the organo lithium catalyst used for forming the living polymer may include hydrocarbons having at least one lithium atom, for example, ethyl lithium, propyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, phenyl lithium, propenyl lithium, hexyl lithium, 1,4-dilithio-n-butane, 1,3-di(2-lithio-2-hexyl)benzene, etc. The preferred organo lithium catalysts are n-butyl lithium, and secbutyl lithium. These organo lithium catalysts can be used alone or in combination of at least two. The content of the organo lithium catalyst, which may be dependent upon the desired molecular weight of the polymer product, is typically 0.1 to 5 mmol and preferably 0.3 to 3 mmol per 100 g of the monomers.
[0021] The specific examples of the hydrocarbon solvent as used for polymerization may include n-hexane, n-heptane, iso-octane, cyclohexane, methylcyclopentane, benzene, and toluene. The preferred hydrocarbon solvents are n-hexane, n-heptane, and cyclohexane.
[0022] In solution polymerization, the content of the monomers in the hydrocarbon solvent is 5 to 40 wt. %, and preferably about 10 to 25 wt. %.
[0023] The addition of the organo lithium compound and the Lewis base, tetrahydrofuran initiates the polymerization reaction. The tetrahydrofuran as a Lewis base is preferably used in an amount of about 50 to 45,000 ppm in the hydrocarbon solvent. The initiation temperature of the polymerization reaction is typically about 0 to 60° C., and preferably about 10 to 50° C. The reaction pressure is preferably 0 to 5 kgf/cm 2 .
[0024] The polymerization reaction proceeds for a sufficient period of time until the monomers are all converted to the copolymer. In other words, the polymerization reaction is performed until a high conversion rate is achieved. Typically, the reaction time is 30 to 200 minutes.
[0025] The specific examples of the Lewis base used for controlling the fine structure of the polymer may include tetrahydrofuran(THF), N,N,N,N-tetramethylethylenediamine (TMEDA), di-n-propyl ether, di-isopropyl ether, di-n-butyl ether, ethyl butyl ether, triethylene glycol, 1,2-dimethoxybenzene, trimethylamine, or triethylamine. The preferred Lewis bases are tetrahydrofuran, and N,N,N,N-tetramethylethylenediamine.
[0026] The copolymer of the present invention is prepared by transforming the active terminal of the polymer using the mixture of a multi-reactive polysiloxane compound and a tin halide compound at the end of the reaction.
[0027] The polysiloxane compound as used herein is a reactive polysiloxane compound having the structure represented by the formula 1. The specific examples of the polysiloxane compound may include α, ω-bis(2-trichlorosilylethyl)polydimethylsiloxane, α, ω-bis(2-dichloromethylsilylethyl)polydimethylsiloxane, and α, ω-bis(2-chlorodimethylsilylethyl)polydimethylsiloxane.
[0028] The tin halide compound is a compound represented by the formula 2, and the specific examples may include tin tetrachloride, trichloromethyl tin, dichloromethyl tin, and trimethyl tin chloride. The preferred tin halide compounds are tin tetrachloride, and trimethyl tin chloride.
[0029] In the mixed coupling agent, the mole ratio of the polysiloxane compound represented by the formula 1 to the tin halide compound is preferably 5:95 to 95:5.
[0030] The content of the mixed coupling agent is an amount of 0.01 to 3 mmol with respect to the organo lithium catalyst.
[0031] The Mooney viscosity (ML 1+4@ 100) of the polymer obtained is 10 to 160, and typically 30 to 150. The vinyl content of the conjugated diene compound in the fine structure is 10 to 90 wt. %, and typically 30 to 80 wt. %.
[0032] The analysis of the polymer synthesized in the present invention was performed in regard to the fine structure of the conjugated diene compound, the compositions of the conjugated diene compound and the aromatic vinyl compound, and the random and block proportions of the conjugated diene compound and the aromatic vinyl compound by using the nuclear magnetic resonance (NMR); the molecular weight (Mw) and the molecular weight distribution (MWD) by using the gel permeation chromatography (GPC); and the Mooney viscosity of the rubber with a Mooney viscometer.
DETAILED DESCRIPTION OF THE INVENTION
[0033] Hereinafter, the present invention will be described in detail by way of the following examples, which describe the preparation method, the degree of coupling, the Mooney viscosity, and the vinyl bonding in the polymer of the SBR random copolymer according to the present invention. The examples are not intended to limit the scope of the present invention. If not specifically mentioned otherwise, the percentage (%) is reduced based on the weight, and the added amount of the randomizer is based on the total amount of the solvent, cyclohexane.
EXAMPLE 1
[0034] In this example, the coupling agent is prepared by mixing the polysiloxane compound and the tin tetrachloride at different mixing ratios, and the coupling rate change, the properties and the processability according to the different mixing ratios were analyzed.
[0035] 204 g(33.3 wt. %) of styrene, 396 g (64.7 wt. %) of 1,3-butadiene and 3,000 g of cyclohexane were added to a 10L-reactor, and then 15 g (5,000 ppm in cyclohexane) of tetrahydrofuran was added to the mixture in the reactor. The internal temperature of the reactor was controlled at 35° C. while operating a mixer. Once the temperature of the reactor reached a predetermined value, 2.7 mmol of n-butyl lithium was added to activate an adiabatic warming reaction. The moment that the reaction temperature was at maximum, another 12 g (2.0 wt. %) of 1,3-butadiene was added so as to substitute the reactive terminal with butadiene.
[0036] Following the second addition of butadiene, 0.3 mmol of polysiloxane halide (Number average molecular weight, Mn 1345) of which the structure is represented by the formula 3 and the number “d” of the repeating units, —O—Si(CH 3 ) 2 — is 13, and 0.068 mmol of tin tetrachloride were added to the reactor. The reaction mixture was kept for a predetermined period of time to active a coupling reaction. After the completion of the coupling reaction, 6 g (1 phr) of an antioxidant, butylated hydroxy toluene (BHT) was added to the reactor to terminate the reaction.
[0037] The polymerized product was added to a steamed warm water to remove the solvent, and then roll-dried to remove the residual solvent and water.
[0038] Subsequently, the final product was analyzed in regard to the molecular fine structure using the NMR, the molecular weight, the coupling degree and the molecular weight distribution using the GPC, and the dynamic characteristic of rubber using the DMTA. The result is presented in Table 1.
(X) a (R) b Si—CH 2 CH 2 —Si(CH 3 ) 2 —[O—Si(CH 3 ) 2 ] d —CH 2 CH 2 —Si(X) a (R) b Formula 3
[0039] where X, R, a, b and d are as defined above in the formula 1.
EXAMPLE 2
[0040] The procedure was performed in the same manner as described in Example 1, excepting that 0.257 mmol of polysiloxane halide (Mn 1345) of which the structure is represented by the formula 3 and the number “d” of the repeating units, —O—Si(CH 3 ) 2 — is 13, and 0.111 mmol of tin tetrachloride were added to the reactor. The reaction mixture was kept for a predetermined period of time to active a coupling reaction. After the completion of the coupling reaction, 6 g (1 phr) of an antioxidant, BHT was added to the reactor to terminate the reaction.
[0041] The subsequent procedure was performed in the same manner as described in Example 1. The result of the polymer analysis is presented in Table 1.
EXAMPLE 3
[0042] The procedure was performed in the same manner as described in Example 1, excepting that 0.368 mmol of polysiloxane halide (Mn 1345) of which the structure is represented by the formula 3 and the number “d” of the repeating units, —O—Si(CH 3 ) 2 — is 13 was added to the reactor. The reaction mixture was kept for a predetermined period of time to active a coupling reaction. After the completion of the coupling reaction, 1.09 mmol of trimethyl tin chloride was added to the reactor to substitute the reactive terminal with the tin compound, and 6 g (1 phr) of an antioxidant, BHT was added to terminate the reaction.
[0043] The subsequent procedure was performed in the same manner as described in Example 1. The results of the polymer analysis are presented in Table 1.
EXAMPLE 4
[0044] In this example, the coupling rate change, the properties and the processability according to the molecular weight of the polysiloxane compound used as a coupling agent were analyzed.
[0045] 0.257 mmol of polysiloxane halide (Mn 901) of which the structure is represented by the formula 3 and the number “d” of the repeating units, —O—Si(CH 3 ) 2 — is 7, and 0.111 mmol of tin tetrachloride were added to the reactor. After the completion of the coupling reaction, 6 g (1 phr) of an antioxidant, BHT was added to the reactor to terminate the reaction.
[0046] The subsequent procedure was performed in the same manner as described in Example 1. The results of the polymer analysis are presented in Table 1.
EXAMPLE 5
[0047] In this example, the coupling rate change, the properties and the processability according to the molecular weight of the polysiloxane compound used as a coupling agent were analyzed.
[0048] 0.257 mmol of polysiloxane halide (Mn 1863) of which the structure is represented by the formula 3 and the number “d” of the repeating units, —O—Si(CH 3 ) 2 — is 20, and 0.111 mmol of tin tetrachloride were added to the reactor. After the completion of the coupling reaction, 6 g (1 phr) of an antioxidant, BHT was added to the reactor to terminate the reaction.
[0049] The subsequent procedure was performed in the same manner as described in Example 1. The result of the polymer analysis is presented in Table 1.
TABLE 1 Mooney Mooney viscosity viscosity (ML 1+4@ 100° C.) (ML 1+4@ 100° C.) Styrene Vinyl Molecular Coupling before after addition content content weight rate (%) addition of oil of oil* (%) (%) distribution Example 1 58 128 52 33.3 36.2 2.10 Example 2 57 126 50 33.3 36.3 1.90 Example 3 59 129 53 33.3 36.5 1.85 Example 4 58 127 52 33.3 36.2 1.95 Example 5 59 129 53 33.3 36.1 2.01
Comparative Example 1
[0050] This comparative example is for preparing a styrene-butadiene copolymer using the technology of the present invention.
[0051] 204 g(33.3 wt. %) of styrene, 396 g (64.7 wt. %) of 1,3-butadiene and 3,000 g of cyclohexane were added to a 10L-reactor, and then 15 g (5,000 ppm in cyclohexane) of tetrahydrofuran was added to the mixture in the reactor. The internal temperature of the reactor was controlled at 35° C. while operating a mixer. Once the temperature of the reactor reached a predetermined value, 2.7 mmol of n-butyl lithium was added to activate an adiabatic warming reaction. The degree of polymerization reaction was determined by observation of the reaction temperature change, and a small amount of the reactant was collected at any time during the reaction to analyze the percentage of the monomers and the conversion rate. The moment that the reaction temperature was at maximum, another 12 g (2.0 wt. %) of 1,3-butadiene was added so as to substitute the reactive terminal with butadiene.
[0052] Following the second addition of butadiene, 0.368 mmol of a coupling agent, α, ω-bis(2-trichlorosilylethyl)polydimethylsiloxane(Mn 1345) of which the structure is represented by the following formula 3 and the number “d” of the repeating units, —O—Si(CH 3 ) 2 — is 13 was added to the reactor. The reaction mixture was kept for a predetermined period of time to active a coupling reaction. After the completion of the coupling reaction, 6 g (1 phr) of an antioxidant, BHT was added to the reactor to terminate the reaction.
[0053] The subsequent procedure was performed in the same manner as described in Example 1. The result of the polymer analysis is presented in Table 2.
Comparative Example 2
[0054] [0054] 204 g(33.3 wt. %) of styrene, 396 g (64.7 wt. %) of 1,3-butadiene and 3,000 g of cyclohexane were added to a 10L-reactor, and then 15 g (5,000 ppm in cyclohexane) of tetrahydrofuran was added to the mixture in the reactor. The internal temperature of the reactor was controlled at 35° C. while operating a mixer. Once the temperature of the reactor reached a predetermined value, 2.7 mmol of n-butyl lithium was added to activate an adiabatic warming reaction. The degree of polymerization reaction was determined by observation of the reaction temperature change, and a small amount of the reactant was collected at any time during the reaction to analyze the monomer proportion and the conversion rate. The moment that the reaction temperature was at maximum, another 12 g (2.0 wt. %) of 1,3-butadiene was added so as to substitute the reactive terminal with butadiene.
[0055] Following the second addition of butadiene, 0.40 mmol of tin tetrachloride was added to the reactor. The reaction mixture was kept for a predetermined period of time to active a coupling reaction, and then the polymerized rubber was analyzed in the same manner as described in Example 1. The result is presented in Table 2.
Comparative Example 3
[0056] [0056] 204 g(33.3 wt. %) of styrene, 396 g (64.7 wt. %) of 1,3-butadiene and 3,000 g of cyclohexane were added to a 10L-reactor, and then 15 g (5,000 ppm in cyclohexane) of tetrahydrofuran was added to the mixture in the reactor. The internal temperature of the reactor was controlled at 35° C. while operating a mixer. Once the temperature of the reactor reached a predetermined value, 2.7 mmol of n-butyl lithium was added to activate an adiabatic warming reaction. The degree of polymerization reaction was determined by observation of the reaction temperature change, and a small amount of the reactant was collected at any time during the reaction to analyze the monomer proportion and the conversion rate. The moment that the reaction temperature was at maximum, another 12 g (2.0 wt. %) of 1,3-butadiene was added so as to substitute the reactive terminal with butadiene. Following the second addition of butadiene, 0.40 mmol of silicon tetrachloride was added to the reactor. The reaction mixture was kept for a predetermined period of time to active a coupling reaction, and then the polymerized rubber was analyzed in the same manner as described in Example 1. The result is presented in Table 2.
TABLE 2 Mooney Mooney viscosity viscosity (ML 1+4@ 100° C.) (ML 1+4@ 100° C.) Styrene Vinyl Molecular Coupling before after addition content content weight rate (%) ddition of oil of oil (1) (%) (%) distribution (2) Comparative 58 128 52 33.3 36.5 2.1 Example 1 Comparative 57 127 51 33.3 35.6 2.0 Example 2 Comparative 58 129 53 33.3 36.2 2.0 Example 3
Experimental Examples 1 to 8
[0057] The polymer prepared in the above examples and comparative examples were used for silica mixing to compare the mixing processability, properties and dynamic characteristics after the mixing. Mix proportions of ingredients are presented in Table 3, and the measurements of properties and dynamic characteristics are presented in Table 4.
TABLE 3 Ingredient Content (g) Polymer 100 Stearic acid 2.0 ZnO 3.0 Silica #175 50 Aromatic oil 20 Si-69 4.0 CZ 2.0 DPG 2.0 Sulfur 1.6 Total 184.6
[0058] [0058] TABLE 4 A1 A2 A3 A4 A5 A6 A7 A8 Copolymer B1 B2 B3 C1 C2 C3 C4 C5 Coupling agent PS 1) SnCl 4 SiCl 4 PS 1) / PS 1) / PS 1) / PS 2) / PS 3) / SnCl 4 SnCl 4 SnCl(Me) 3 SnCL, SnCL, Mole ratio (%) of 100 100 100 81.5/ 69.8/ 25.2/ 69.8/ 69.8/ Coupling agent 18.5 30.2 74.8 30.2 30.2 Mooney viscosity 100 80 99 88 85 99 86 85 (ML 1+4@ 100) Hardness 66 67 66.5 66 66 67 66 66 (Shore-A) Tensile strength 176 147 170 174 172 174 175 176 (kgf/cm 2 ) 300% Modulus 98 85 89 95 94 95 95 93 (kgf/cm 2 ) Percentage of 460 500 490 450 480 490 480 470 elongation (%) Tg (° C.) −7.9 −9.4 −9.7 −8.4 −8.2 −9.1 −8.2 −8.0 Tan δ at 0° C. 0.6817 0.6764 0.6690 0.6950 0.6901 0.6955 0.7010 0.7113 Tan δ at 60° C. 0.0717 0.0786 0.0725 0.0702 0.0710 0.0710 0.0711 0.0698
Experimental Examples 9 to 16
[0059] The polymer prepared in the above examples and comparative examples were used for silica-carbon black compounding to compare the mixing processability, and the properties and dynamic characteristics after the mixing. Mix proportions of ingredients are presented in Table 5, Measurements of properties and dynamic characteristics are presented in Table 6.
TABLE 5 Ingredient Content (g) Polymer 100 Stearic acid 2.0 ZnO 3.0 Silica #175 20 Carbon black (N-330) 30 Aromatic oil 18.0 Si-69 1.6 CZ 2.0 DPG 2.0 Sulfur 1.5 Total 180.1
[0060] [0060] TABLE 6 A9 A10 A11 A12 A13 A14 A15 A16 Copolymer B1 B2 B3 C1 C2 C3 C4 C5 Coupling agent PS 1) SnCl 4 SiCl 4 PS 1) / PS 1) PS 1) / PS 2) / PS 3) / SnCl 4 SnCl 4 SnCl(Me) 3 SnCl 4 SnCl 4 Mole ratio (%) of 100 100 100 81.5/ 69.8/ 25.2/ 69.8/ 69.8/ coupling agent 18.5 30.2 74.8 30.2 30.2 Mooney viscosity 65 55 64 60 59 65 59 58 (ML 1+4@ 100) Hardness (Shore-A) 64 63 64 64.5 64 63.5 65 64 Tensile strength 210 190 195 220 215 215 215 220 (kgf/cm 2 ) 300% Modulus 98 93 95 100 96 102 98 99 (kgf/cm 2 ) Percentage of 510 500 505 520 510 510 520 530 elongation (%) Tg (° C.) −8.5 −10.2 −9.5 −8.2 −8.4 −9.4 −8.5 −8.6 Tan δ at 0° C. 0.7325 0.6953 0.7012 0.7631 0.7521 0.7723 0.7621 0.7701 Tan δ at 60° C. 0.0801 0.0853 0.0876 0.0702 0.0715 0.0709 0.0715 0.0712
[0061] As described above, when using the rubber prepared by using a mixed coupling agent of the multi-reactive polysiloxane represented by the formula 1 and the tin compound represented by the formula 2 as a material for tires, the multi-reactive polysiloxane and the tin halide compound used for the coupling agent lead to a remarkable increase in the compatibility with reinforcing materials used in the manufacture of tires, i.e., silica and carbon black, relative to conventional products, improving of the manufacturing processability of tires. Substantially, the use of an inorganic filler consisting of carbon black or silica solely, or a silica-carbon black mixed inorganic filler enhances the tread wear necessary for tires in the mixing, with a high wet traction and a low rolling resistance, and improves properties in the aspect of mixing processability.
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Disclosed is a copolymer prepared from a conjugated diene monomer and a vinyl aromatic monomer. The radial copolymer is prepared by coupling the terminal of a leaving polymer using a mixed coupling agent comprising the mixture of a multi-reactive polysiloxane and a tin halide compound, the leaving polymer being prepared by copolymerizing a conjugated diene monomer and a vinyl aromatic monomer in the presence of an organo lithium catalyst and a hydrocarbon solvent. The use of the radial copolymer improves the affinity to silica or carbon black used as a filler, and remarkably enhances processibility in the manufacture of tires as well as the properties (e.g., higher wet traction, lower rolling resistance, and higher tread wear) necessary for tires relative to the conventional products.
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FIELD AND BACKGROUND OF THE INVENTION
The present invention relates in general to insulated hot fluid injection tubing and more particularly to a new and useful arrangement for maintaining a vacuum in an annular space between inner and outer tubulars forming an insulated tubing.
Heavy oil and tar sands represent huge uptapped resources of liquid hydrocarbons which will be produced in increasing quantities to help supplement declining production of conventional crude oil. The deposits must, however, be heated to reduce the oil viscosity before the oil will flow to the producing wells in economical quantities. A dominant method of heating is by injection of surface generated steam in either a continuous (steam flood) or intermittent (steam stimulation or "huff and puff") mode.
When steam is injected down long injection pipes or "strings", a significant amount of thermal energy is lost to the rock overburden (500 to 7,000 feet) which covers the oil deposits if the strings are not properly insulated. In initial steam injection projects, the price of oil did not justify the prevention of this heat loss, but with the price of oil at $30 or more a barrel, insulation systems for the well injection pipe become economically justified.
It is known to use insulated steam injection tubing for the injection of steam into oil wells and the prevention of excessive heat loss.
Tubing of the insulated steam injection type is formed of coaxial inner and outer tubulars that are connected together whereby an annular space is formed there-between. The annular spaces are typically insulated by products such as fiber and layered insulation with air or inert gas typically in the annular spaces.
The provision of a vacuum within an annular space between inner and outer tubulars is disclosed in U.S. Pat. No. 3,680,631 to Allen et al. and U.S. Pat. No. 3,763,935 to Perkins. Both of these references deal with the conveyance of warm fluid, such as oil over cool environments such as permafrost zones wherein the fluid, specifically liquid petroleum, is to be conveyed typically at a temperature of 160 degrees F.
Both of these patents suggest the use of special coatings, such as nickel or chromium alloy coatings, on the tubular surfaces to reduce gas diffusion into the space so that the vacuum which is originally established in the annular space can be maintained. Both patents generally suggest the use of a getter material for absorbing gases which may invade the annular space.
While the problem of gases diffusing or leaking into an evacuated annular space of a double walled tube is treated generally in the Allen et al and Perkins patents, neither of these patents address additional problems which are faced in the rugged environment of an oil well undergoing steam injection. The outer surfaces of the outer tubular in such an environment are exposed to corrosive water under pressure, which pressure increases with well depth. The tubing is generally made of carbon steel for economic reasons, and the corrosive environment drastically increases the generation of nascent hydrogen that permeates the outer tubular wall in particular at the greatly increased pressures encountered in typical water depths of 4000 to 6000 feet or more.
In addition, under the high temperature conditions of the inner tubular, the outgassing of objectionable gases such as oxygen, carbon monoxide, hydrogen, and nitrogen into the annular space increases in the order of an estimated ten times or more over the outgassing rate when the fluid in the inner tubular is at a temperature of merely 160 degrees F. Again, for economic reasons, the inner tubular should normally be made of relatively inexpensive metals such as carbon steel. While baking is known for the purposes of outgassing the surface of such steel, it is estimated that sufficient degassing of the inner tubular would require a temperature of 1,800 degrees F. for a period of about a day. Such processing is generally impractical, however.
During the life of an insulated steam injection tubing, which is estimated to be at least five years, an increase in hydrogen partial pressure within the annular space of up about four torr can be expected due to hydrogen diffusion. An increase in partial pressure from other active gases of 100 torr can be expected from outgassing of the inner tubular. Such increases in pressure defeat the insulating function of the annular space. Although partial pressures of other gases of up to 0.1 torr can normally be tolerated, a partial pressure above 0.01 torr cannot normally be tolerated for hydrogen due to its greater mobility.
In an article entitled New Double-Walled Tubulars Can Aid Thermal-Recovery Operations, B. V. Traynor, Oil and Gas Journal, Feb. 18, 1980, the problems of insulating the annular spaces of double-walled tubing in a rugged oil well environment are discussed on p. 106. It is noted that the use of a vacuum in the annular space for insulation purposes was found to be economically impractical so that the vacuum approach has been abandoned.
SUMMARY OF INVENTION
The present invention provides a solution to the problems of maintaining a vacuum in the annular spaces of tubing having inner and outer tubulars and used to inject steam into an oil well.
According to the invention, getter material is placed in the annular space during assembly of the tubulars. The getter material is advantageously positioned adjacent a surface which will achieve a high temperature during service. This increases the capacity and pumping speed of the getter material. The inner and outer tubulars are assembled using connecter means such as plates which are welded to the tubulars whereby an annular space is provided therebetween. The space is sealed and evacuated. The getter material is preferably simply and automatically activated by heating when the tubing is utilized for steam injection.
Accordingly, an object of the present invention is to provide a tubular apparatus for the delivery of steam or other hot fluids to a well comprising an inner tubular having an outer surface and defining an inner space for conveying fluids at a temperature of greater than 400 degrees F., an outer tubular disposed around the inner tubular and defining an annular space therewith, means for connecting the inner and outer tubulars, the annular space closed to atmospheric pressure and a vacuum established in the closed annular space, and a getter material for absorbing at least one active gas in the closed annular space, the getter material being disposed preferably adjacent the surface of the inner tubular or another high temperature component in the apparatus.
A further object of the present invention is to provide such a tubular apparatus whereby an acceptable vacuum may be maintained in the annular space when the inner tubular is made of material which releases at least one active gas by outgassing, which outgassing is increased with elevated temperatures.
A further object of the present invention is to provide such a tubular apparatus whereby an acceptable vacuum may be maintained in the annular space when the outer tubular is made of material which corrodes in a corrosive environment of a well to generate nascent hydrogen which penetrates the outer tubular and enters the annular space.
The invention advantageously can help avoid the use of costly corrosion resistent materials as coatings for the inner and outer tubulars.
The getter material may be made of titanium, zirconium, or other gas absorbing materials. However, titanium and zirconium are preferred for absorbing hydrogen gas.
A further object of the invention is to provide a tubular apparatus for the delivery of steam to a well in which a vacuum environment used for insulation is maintained within desired limits throughout the life of the tubular apparatus, and which is simply designed, rugged in construction, and economical to manufacture.
For an understanding of the principles of the invention, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the Drawings:
FIG. 1 is a longitudinal sectional view of insulated steam injection tubing according to the invention; and
FIG. 2 is a cross-sectional view of another embodiment of the insulated steam injection tubing according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings, in particular, the invention embodied therein comprises an insulated hot fluid injection tubing apparatus generally designated 10, which apparatus can be assembled with other similar tubing to form a string which is lowered into an oil well for the purposes of injecting steam or other hot fluids therein. The tubing 10 is typically about 40 feet in length and comprises an outer tubular 12 disposed around an inner tubular 14 and defining therewith an annular space 16. Annular space 16, as shown in FIG. 1, can be provided with multi-layered insulation 18 wrapped around an outer surface 20 of inner tubular 14, or, as shown in FIG. 2, fibrous insulation 22. However, other suitable insulation may be used. Connecting means such as flanged connecting members 24 and 26 are connected, preferably welded, between the inner and outer tubulars at axially spaced locations. In addition to connecting inner and outer tubulars, members 24 and 26 may serve to advantageously seal the annular space 16. A fluid supply device 34 may be connected to tubing 10 by means of the line schematically illustrated at 36 to supply steam or other hot fluid to the tubing. Device 34 may be of any type known in the art for that purpose, and such devices are commonly known to those of ordinary skill in the art to which this invention pertains.
Annular space 16 is vacated in known fashion to a level preferably at or below 10 -3 torr.
With an estimated service life of about five years or longer, it is desired that this level of vacuum be maintained at or below 0.1 torr including a partial pressure below 0.01 torr for hydrogen. Above these pressures, the thermal insulating function of the annular space is degraded. This is due, in the case of hydrogen, to the light weight and fast movement of hydrogen molecules that undesirably transfer heat from the inner tubular 14 to the outer tubular 12. The vacuum, as noted above, also deteriorates due to outgassing of active gases such as oxygen, nitrogen, hydrogen, and carbon monoxide from the material of the tubulars, in particular the inner tubular 14 which is exposed to steam conducted in its inner space 28, which inner tubular is typically at a temperature of about 650 degrees F. and generally within a temperature range of 400 to 700 degrees F.
As will be discussed in greater detail hereafter, during service life of a tubular apparatus 10, the atmosphere within annular space 16 can be expected to increase by up to about four torr due to diffusing hydrogen generated by corrosion, and by about 100 torr due to outgassing of gases from the hot inner tubular 14. Thus, even without otherwise mechanical leakage of gases into the annular space which may occur, the upper limits at a total pressure of 0.1 torr and a hydrogen partial pressure of 0.01 torr for the annular space 16 is far exceeded.
To eliminate such undesirable active gases from the annular space 16, and according to the invention, a getter material 30 is provided within the annular space and preferably adjacent the outer surface 20 of inner tubular 14 or another surface such as the surface of a connecting member 24 or 26 which may also be at a temperature of more than 400 degrees F. In this location, the getter material which is preferably activatable by heat of steam in space 28, absorbs both hydrogen permeating through the outer tubular wall and gases outgassed from the inner tubular 14. To increase the surface area of the getter material, the getter material can, for example, advantageously be of a sponge form which is a form providing a large surface area and is commonly known to those of ordinary skill in the art to which this invention pertains, or it may be provided on a corrugated metal strip, shown at 32 in FIG. 2; that surrounds and is adjacent the outer surface of inner tubular 14. The corrugated strip 32 may, for example, be iron or another metallic alloy, with the getter material formed in a coating on the strip.
The getter material is advantageously titanium, an alloy of titanium, zirconium or an alloy of zirconium for absorption of hydrogen as well as other active gases. Getter material such as aluminum may be added for absorbing other active gases. These getter materials may be activated, or increased in activity at elevated temperatures, typically the temperatures within space 28, to absorb the objectionable active gases that would otherwise migrate into space 16.
In this way, relatively inexpensive mild carbon steel can be used for constructing inner and outer tubulars without corrosion resistant diffusion coatings such as chromium or nickel plating or stainless steel. This results in significant "savings" in manufacturing of the tubular apparatus 10 while at the same time maintaining a sufficient vacuum insulation during its service life.
While the tubing is primarily useful in the rugged environments of an oil well for oil recovery, the tubing is also useful in other similarly rugged environments such as those of oil-coal slurry transportation and steam and high pressure hot water circulation in geothermal wells.
In calculating the amount of hydrogen which may permeate into the annular space 16, an outer surface of outer tubular 12 is assumed to have an area of 232.7 cm. 2 per inch of tube length. The water volume in the annular space between the well casing (not shown in FIG. 1) and the insulated tube is assumed to be 369.86 cm. 3 per inch of the tube length. The volume of the evacuated space 16 in the insulated tube is assumed to be 133.27 cm. 3 per inch of the tube length. These figures are based on typical sizes for the inner and outer tubulars.
The density of carbon steel, of a type advantageously used according to the invention, is 7.86 g/cm. 3 .
A corrosion mechanism in acid or alkali solution is as follows:
Fe→Fe.sup.2+ +2e: anodic reaction
2H.sup.+ +2e→H.sub.2 (gas): cathodic reaction
Corrosion of 1 g-ion of Fe (55.85 g) evolves 1 g-mole of H 2 .
In addition to the above, the following assumptions are made:
Corrosion rate of carbon steel: 1 mpy (mil per year)
Outer surface area of the insulated tube: 91.16 cm 2 per inch of tube.
Inner surface area (exposed to steam) of the inner tubular: 48.12 cm 2 per inch of tubular.
Wall thickness of the outer tubular: 0.635 cm.
Wall thickness of the inner tubular: 0.483 cm.
Permeation coefficient U can be calculated according to the equation
U=U.sub.o e(-K/RT)
where
U o =2.83×10 -3 cm 3 /cm-sec-atm 1/2
K=8,400 cal/g-mole.,
R=the universal gas constant, and
T=temperature in degrees Kelvin.
At temperatures of 150,400, and 650 degrees F., the permeation coefficient U is found to be as follows:
U 150 degrees F.=1.1×10 -8 cm 3 /cm-sec-atm. 1/2
U 400 degrees F.=4.1×10 -7 cm 3 /cm-sec-atm. 1/2
U 650 degrees F.=2.95×10 -6 cm 3 /cm-sec-atm 1/2
The hydrogen partial pressure in the steam side of the inner insulated tubular is assumed to be zero. With Q 1 being the hydrogen flux from water to the vacuum space of the insulated tube, and Q 2 being the hydrogen flux from the vacuum space of the insulated tube to the steam, the steady state condition is Q 1 =Q 2 .
Q is calculated according to the following equation: ##EQU1## where A=surface area in cm 2
P=the difference in pressure in atmospheres between inside and outside of a tubular, and
t=thickness in cm. of the tubular wall.
Based on the above assumptions and setting Q 1 =Q 2 , the partial pressure of hydrogen in the vacuum space of the insulated tube under steady-state conditions is estimated for an inner tubular temperature in the range of 400 to 650 degrees F. to be as listed in Table I or greater.
TABLE I______________________________________HYDROGEN PARTIAL PRESSURE AS A FUNCTION OFDISTANCE BELOW WATER SURFACEDepth (ft) H.sub.2 Partial Pressure (Torr.)______________________________________ 0 2.1 × 10.sup.-2 500 3.2 × 10.sup.-11000 6.4 × 10.sup.-12000 1.274000 2.556000 3.82______________________________________
From this table, it may be observed that the annulus pressure due to permeation of hydrogen into the annulus under steady-state conditions is unacceptably high (above 0.01 torr) even at the water surface if an effective means is not provided for absorbing the hydrogen gas.
While various corrosion inhibitors can be utilized to inhibit corrosion or prevent the passage of hydrogen into the vacuum space as noted above, this increases the cost of using insulated tubing.
By using titanium or zirconium, each of which have a strong affinity for hydrogen gas, as a hydrogen getter in a vacuum space, hydrogen as well as other gases can be absorbed from the vacuum space to prolong the useful life of the insulated tubing according to the invention.
The reaction of titanium as a hydrogen getter is as follows:
Ti(s)+H.sub.2 (g)→TiH.sub.2 (s)
(s) signifies a solid and (g) signifies gas
The free energy of formation and the dissociation pressure of titanium hydride are shown as a function of temperature in Table II. The large negative value of free energy and the low dissociation pressure indicate that titanium can serve as an efficient hydrogen getter in the vacuum space of the insulated tube.
TABLE II______________________________________FREE ENERGY OF FORMATION ANDDISSOCIATION PRESSURE OF TITANIUMHYDRIDE AS A FUNCTION OF TEMPERATURE Free EnergyTemperature of Formation Dissociation Pressure of TiH.sub.2(degrees F.) (cal) (Atm.)______________________________________ 80 -25,067 10.sup.-18.3260 -28,845 10.sup.-11.9400 -20,813 10.sup.-9.5440 -18,518 10.sup.-8.1620 -15,144 10.sup.-6.0650 -10,579 10.sup.-5.2______________________________________
Assuming the service life of tubing 10 to be about five years, and to preserve a final vacuum within annular space 16 of no more than 0.1 torr including a hydrogen partial pressure no more than 0.01 torr, this space should first be evacuated to a level of 10 -3 torr or less as noted above. Assuming hydrogen will contribute a partial pressure of about four torr and all of the gases will contribute about 100 torr pressure, the use of a getter material within the annular space should maintain the vacuum level at the end of the service life of the tube well below 0.1 torr including a hydrogen partial pressure no more than 0.01 torr.
While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that this invention may be embodied otherwise without departing from such principles.
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Tubular apparatus for delivering steam or other hot fluids to an oil well comprises an inner tubular having an outer surface and defining an inner space for conveying fluids at a temperature greater than 400 degrees F., and an outer tubular disposed around the inner tubular and defining an annular space with the inner and the outer tubulars being connected together. The annular space is closed to atmospheric pressure. A vacuum is established within the annular space. A getter material for absorbing at least one active gas is disposed within the annular space. Active gases which are absorbed by the getter material include hydrogen formed by corrosion of the outer tubular which hydrogen migrates through the outer tubular into the annular space and gases such as nitrogen, carbon monoxide, and hydrogen that are released from the inner tubular at elevated temperatures.
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DEDICATORY CLAUSE
The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to me of any royalties thereon.
BACKGROUND OF THE INVENTION
Electromagnetic radiation (EMR) testing is presently hampered by reflections and resonances in the single testing chamber. Electromagnetic interference (EMI) from outside the chamber also occurs. A typical conventional test chamber can include a transmitter and antenna for directing electromagnetic radiation across a space toward a test specimen rotatably mounted. The rotatable specimen is normally moved to a test position and stopped for each test. Depending on the size of the specimen, such as a missile, tank, or other structure which may house equipment affected by EMR, such as electronic circuits, the space required for rotatably testing may be a limiting factor. For a missile, the longitudinal axis of the test specimen is positioned at some variable angle B with respect to the EMR propagation direction. This is done by support assembly and rotating table. Testing which must be done at outdoor, unshielded facilities are also subject to EMI.
The effect of impinging EMR on missile systems such as the guidance and control systems within a missile housing may be detected or maintained in several ways during testing. An antenna may be placed inside the test specimen housing to pick up the radiation pattern developed. This detected radiation may then be coupled out to monitoring detector equipment. Fiber optics may be utilized to monitor guidance and control telemetry to determine radiation effects. If the specimen is food to be cooked or involves a chemical curing process or sterilizing of equipment, a pickoff or detector is unnecessary.
Present EMR radiated susceptibility testing of electronic equipment is normally conducted in an electromagnetic shielded enclosure. The EMR is launched from an antenna to the test item but reflections in the enclosure (from the enclosure walls and other test support hardware) cause serious perturbation in the EMR fields. Chambers are lined with EMR absorbing material to reduce reflections. This material (sometimes referred to as anechoic) is expensive and partially effective.
SUMMARY OF THE INVENTION
In the multiple cell electromagnetic radiation test system a plurality of strip transmission line cells are coupled in physical and electrical series for providing EMR field steering by electronics phase shifting. Apertures in the walls of the cells provide a space for test specimens to be inserted into the cell system. This arrangement allows a fixed or unmoved test specimen to be subjected to EMR radiation fields that have previously required rotation or repositioning of the specimens. The phase and arrival time of each cell voltage is controlled to provide the same EMR impingement of the test sample as would have been provided with a rotatable table system at selected angles of rotation with respect to a reference position. Each cell of the system may be electrically isolated from adacent cells by gas or fluid driven electric generators and fiber optics.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of a system providing conventional electromagnetic radiation of a test specimen, showing illustrative phase variation at the specimen.
FIG. 2 is a diagrammatic view of a single strip transmission line cell having apertured walls and input-output connections shown in schematic form.
FIG. 3 is a diagrammatic view of several cells having coaxial apertured walls for receiving test specimens.
FIG. 4 is a block diagram of a preferred multiple cell EMR test system.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings wherein like numerials refer to like parts in the several Figures, FIG. 1 discloses a typical prior art test system. A transmitter 10 is disposed for supplying electromagnetic radiation (EMR) at a preselected frequency to antenna 12. A test specimen such as a missile 14 is disposed on a rotatable table 16 in the path of electromagnetic radiation 18 from antenna 12. The longitudinal axis of missile 14 is aligned at some variable angle B with respect to the EMR on a normal to the antenna emitting surface. For a fixed position of the antenna and the specimen and a particular frequency of radiation, a unit area of the specimen will always be subjected to the same degree of radiation as shown in the typical electric field amplitude curve of FIG. 1. Three points on the missile (1, 2, and 3) are at the respective nose, center, and tail sections. EMR arrives at (1) before (2), and at (2) before (3). For example, when the EMR arriving at point (3) has a phase of 0° the EMR arriving at (2) is 45° out of phase with (3) and similarly 90° out of phase with point (1). As the radiation wave continuously impinges on the fixed missile, each point continuously receives radiation which differs in phase. To change the radiation impingiment angle on the specimen, it must be rotated to a new B position. Thus, in testing a missile for response during radiation or for adverse effects of radiation thereon, the missile must be maneuvered through considerable positions to supply radiant energy to each per unit area of the missile or area of interest. This results in cumbersome support equipment and positioners, especially for larger specimens.
The multiple cell test system provides capability for phase shift at each cell to simulate the wave arriving from angles other than broadside (B=90°). Broadside testing can be accomplished without phase shift between cells. FIG. 2 shows a single cell 20 having apertured, metal walls. Walls 22 and 24 each have respective apertures 23 coaxially therethrough. The edge or surface of each aperture may be coated with an insulating material 25 to prevent conduction between the walls 22, 24 and a test specimen inserted in the aperture. The space between walls may be air or dielectric; or dielectric support rods 28 may be utilized, maintaining the spacing and characteristic impedance between walls of each cell. At the respective feed input end 30 and load end 32 of each cell, the respective walls taper down and converge toward a common point to maintain the desired characteristic impedance common in strip line structures. The spacing between walls 22 and 24 is small compared to the wavelength of the test frequency. In construction the tapered surfaces 34A-D increase as the distance away from terminals 30 and 32 increase and the space between adjacent surfaces increases so that the characteristic impedance remains constant. Parallel wall portions 35A and 35B interconnects the respective tapered portions 34, maintaining characteristic impedance therebetween. In applying EMR to a specimen within the cell 20, radio frequency energy is supplied, as by a strip transmission line or coaxial cable 38 to input 30 and is dissipated in load 39.
FIG. 3 discloses several test cells 20A, 20B, and 20C. Each cell 20 has a separate input and load. Each cell may be individually constructed with respective interior walls joined together or may be constructed sharing a common wall with adjacent cells. Each cell is a strip transmission line for providing electrical matching of the feed diverging plates 34A and 34D, the rectangular cell plates 35, the converging plates 34B and 34C and the load to the input characteristic impedance.
FIG. 4 discloses a block diagram of a typical multiple cell test system. Typically each cell 20 has a load 39 and is coupled through a transmission line 38 to a transmitter 42. Transmitter 42 is powered by an electronic generator 44 driven by a gas or fluid compressor 46 coupled to generator 44 with non-conductive tubing 48 to provide isolation between cells. Alternatively, the transmitter may be driven by light from photovoltaic cells via light pipes instead of tubing 48 (not shown). Each transmitter 42 is further coupled back through a photodiode circuit 50, non-conductive fiber optics 52, a light emitting diode circuit 54, and a phase shifter 56 to a common signal generator 58. Alternatively, the signal generator 58 can be coupled directly to LED circuit 54 and the phase shifter 56 placed between transmitter 42 and cell 20.
In operation, a test specimen 60 is placed into the cell apertures for testing. The energy associated with these fractional wavelength cells adds to provide the test EMR fields through the test specimen 60. The signal generator 58 output is divided into separate signals for each cell. The signal to each cell can be the same phase or can be shifted in phase by phase shifters 56 to provide the capability of varying the relative phase and electric energy arrival time at each cell. These delays or phase shifts provide illumination of test specimens at varying illumination angles. The variation in phase between cells simulates EMR arriving at a positionable test specimen from a distance source at varying angles. Thus, for a typical arrangement of 10 cells fed from 10 phase shifters, each having 10° shift from the adjacent cell, a phase shift of from 0° at the first cell to 90° at the last cell occurs. A typical wave for each cell is shown developed across specimen 60, having a phase shift from 0° to 90° over a 10 cell system. The developed phase shift in each cell may be variable, changing the EMR impinging on the specimen over a given area.
The effect of such EMR on the test specimen 60 is evidenced in any of several ways. For example the various systems and electronic circuits may subsequently be removed from the test cells and tested for any characteristic response changes. Also, the specimen 60 may have an antenna therein, such as within a missile housing, coupled to recording circuitry for receiving and recording the EMR intensity passing through the housing. Where the test specimen involves curing a chemical process, cooking foods, or equipment sterilization an indicator of temperature, or processing time may be employed and no EMR pickoff required.
The light emitting diode, fiber optic, and photodiode converter circuitry together with the electrically isolated generator for the amplifier transmitter provides substantial electrical isolation. The photodiode 50 converters provide an electric signal output to each cell 20, which is identical to the phase shifter output 56 used to drive LED 54. The location of phase shifter 56 at the signal generator provides for phase shifts and delays being done at a low voltage for amplification at each cell. The amplified signal from transmitters 42 are transmitted through each cell into the respective loads, while the electromagnetic radiation developed within each cell are joined as a wavefront as a result of the cell interconnection. This wavefront induced into the test specimen simulates that which would be induced in it if the specimen were located in free space. The characteristic impedance of each cell is electrically matched to the amplifier and each cell is terminated in its characteristic impedance load, thereby preventing reflections in the cells.
Each cell provides a characteristic impedance match to the transmitter that energizes it and to the load that disipates the energy passing through it. Each cell is maintained small compared to the shortest wavelength utilized to maintain proper characteristic impedance. Typically, for a 300 MHz frequency from generator 58 and an air dielectric between the plates of each cell 20, an electromagnetic energy transmission wavelength of approximately 1 meter is provided. A spacing of approximately 1/10 meter (wavelength) between the plates of each cell will make the width of each cell small compared to a wavelength.
Advantages of the system include EMR test fields being induced into the test specimens free of EMR reflections and resonances encountered in present test chambers. The EMR test field may be steered by phase shift or delay networks. This steering can provide directing of the EMR fields to impinge on the test specimens from selected angles. Expensive and clumsey positioners are not required. The EMR test system is extremely efficient, since most of the energy impinges directly on the test specimen. Emission of EMR from the system into the atmosphere is low, providing for eliminating or reducing electromagnetic interference problems and the need for frequency allocations. High level EMR fields can be generated utilizing low power amplifiers. The system provides for simplified tests of large systems. Multiple test chambers (multiple cell arrays) may be utilized with separate test specimens simultaneously.
Although the present invention has been described with reference to the preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. Accordingly the scope of the invention should be limited only by the claims appended hereto.
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A multiple cell electromagnetic radiation testing system includes a plurality of isolated strip transmission line cells coupled in electrical series and having aligned apertures in the walls of the cells. With this arrangement the respective cells bounded waves add to simulate application of a single electromagnetic radiation field at test specimens located in the apertures of the cell walls. Each cell has a plate-to-plate dimension that is small compared to a wavelength of the highest test frequency. The phase and arrival time of each cell voltage is controlled to simulate electromagnetic radiation impingement of the test sample at selected angles.
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TECHNICAL FIELD
The present invention relates to a technique for sharing a first plurality of transponders among the same or larger number of input and output signaling directions and, more particularly, to a technique which concurrently and rapidly scans each transponder over appropriately defined group pairs of the input and output signaling directions to match satellite resources with terrestrial traffic patterns.
BACKGROUND ART
The early satellite communication system designs employed an area coverage beam which provided interconnections on either a time-division multiple access (TDMA) basis or a frequency-division multiple access (FDMA) basis. Such designs had the disadvantage of low antenna gain and frequency reuse only by the use of polarization techniques. More recent designs use (a) multiple narrow-angle fixed spot beams with onboard satellite switching to provide frequency reuse, high capacity, and high antenna gain, (b) a single scanning beam to provide high antenna gain, (c) the combination of an area coverage beam and multiple narrow-angle fixed spot beams to provide high capacity, and (d) the combination of multiple narrow-angle fixed spot beams and a single scanning beam with on-board satellite switching.
A typical prior art design is shown in U.S. Pat. No. 3,711,855, issued to W. G. Schmidt et al on Jan. 16, 1973, which illustrates a conventional multiple-transponder satellite with n transponders for n or more ground stations where each transponder covers a particular portion of the frequency spectrum and no two ground stations may concurrently transmit in the same frequency band. Another design is shown in U.S. Pat. No. 3,924,804, issued to W. G. Schmidt et al on Dec. 23, 1975, where a plurality of receive spotbeam antennas are selectively connected to a plurality of transmit spotbeam antennas by an on-board switching matrix. Additionally, several other separate receive and transmit spotbeam antennas are connected to a common receiver and transmitter, respectively, by a respective on-board input and output switch.
An article "Analysis of a Switch Matrix for an SS/TDMA System" by Y. Ito et al in Proceedings of the IEEE, Vol. 65, No. 3, March 1977 at pp. 411-419 discloses a technique which provides a most efficient utilization of a frame period with n 2 -n numbers of switchings at most, where n is the number of beams in the SS/TDMA system.
A major problem in multibeam satellite design is one of transponder reliability. Unlike area coverage systems wherein the allocated band is divided among several transponders and service is provided via frequency division multiple access, it is desirable to serve each spot beam of a multibeam satellite system with a single transponder. With this approach, the required number of transponders is kept from becoming prohibitive, and the weight of the communications subsystem is minimized. However, sufficient redundancy must be provided to ensure high reliability for each transponder since single failures would preclude continuing service to the area serviced by that transponder. By contrast, for area coverage systems using frequency division multiple access, isolated failures merely cause a slight increase in the demand presented to the surviving transponders.
A second problem in multibeam satellite systems concerns efficient utilization of the satellite transponders. In general, the traffic demands from the various coverage areas, or footprints, are nonuniform. Thus, to utilize each transponder fully, the capacity of each must be tailored to the traffic demand of the area covered by that transponder. A technique for achieving such a custom fit has been disclosed in the article "An Efficient Digital Satellite Technique for Serving Users of Differing Capacities" by H. W. Arnold in ICC Conference Record, June 12-15, 1977, Chicago, Ill., Vol. 1, at pp. 6.1-116 to 6.1-120 wherein the bit-rate of each beam is selected as a fixed multiple of some basic rate. At the satellite, each up-link beam is demultiplexed into several basic rate bit streams, switched, and then remultiplexed into down-link beams. One disadvantage of this scheme is that on-board demodulation and remodulation is required. However, a more serious disadvantage in such a system is the need for nonidentical transponders which precludes sharing of a common pool of spare transponders among all beams, and the reliability of the system suffers.
A third problem of multibeam satellites involves means of accessing traffic from areas not within the footprint of some spot beam. Several solutions have been proposed in the article "Spectral Reuse in 12 GHz Satellite Communication Systems" by D. O. Reudink et al in ICC Conference Record, June 12-15, 1977, Vol. 3 at pp. 37.5-32 to 37.5-35 involving sharing the spectrum between spot beams and an area coverage beam. These have the disadvantage that the area coverage transponders are different from the spot beam transponders and have higher power requirements to compensate for the loss of antenna gain. Also, the fixed spot beam transponders, when assumed identical, are not matched to traffic requirements of the area served.
Another solution to the access problem as disclosed in the article "A Scanning Spot Beam Satellite System" by D. O. Reudink et al in Bell System Technical Journal, Vol. 56, No. 8, October 1977 at pp. 1549-1560 involves the use of a steerable spot beam which can be rapidly scanned across the entire service region via a phased array antenna, thereby providing universal coverage. When used in conjunction with a multitude of fixed spot beams, the resulting hybrid system has the advantages of frequency reuse, high antenna gain, and identical transponders. However, such a hybrid system does not utilize the transponders efficiently because of nonuniform traffic demands from the various ground areas covered.
The problem, therefore, remaining in the prior art is to provide a satellite system concept whereby the resources such as, for example, the available power and transponders at the satellite are most efficiently matched to the instantaneous terrestrial traffic patterns, while providing uniform coverage over a wide service area, with identical or nearly identical transponders.
BRIEF SUMMARY OF THE INVENTION
The foregoing problem has been solved in accordance with the present invention which provides a technique for sharing a plurality of transponders among a same or larger number of input and output signaling directions and, more particularly, to a technique which rapidly scans each transponder over appropriately defined group pairs of the input and output signaling directions to match satellite resources with terrestrial traffic patterns.
It is an aspect of the present invention to provide a technique for providing an efficient TDMA slot assignment sequence for each of a plurality of transponders which accommodates nonuniform ground station traffic requirements by concurrently scanning the transponders over separate group pairs of ground areas.
It is a further aspect of the present invention to provide a technique for sharing a first plurality of transponders among a same or larger number of input and output signaling directions which uses apparatus comprising scanning means which concurrently and selectively scans the input and output terminals of the transponders over appropriately defined group pairs of the input and output signaling directions as defined by a predetermined TDMA slot assignment sequence for each transponder.
Other and further aspects of the present invention will become apparent during the course of the following description and by reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring now to the drawings, in which like numerals represent like parts in the several views:
FIG. 1 is a block diagram of a satellite communication subsystem arrangement for the rapid scanning of n multiple transponders over appropriately defined group pairs of a plurality of m input and output signaling directions in accordance with the present invention;
FIG. 2 is a block diagram of an alternative arrangement of the subsystem of FIG. 1 in accordance with the present invention;
FIG. 3 is an illustrative reduction of a 3-by-3 traffic matrix comprising 20 units of traffic for two transponders each of a capacity of 10 traffic units per frame in accordance with the present invention;
FIG. 4 is a TDMA frame assignment sequence for the exemplary reduction of FIG. 3 where the numbers 1 through 3 represent the spot beam coverage areas of the 3-by-3 traffic matrix;
FIG. 5 is an illustrative reduction of a 4-by-4 traffic matrix by removing more than one unit of capacity per diagonal at a time where the matrix comprises 39 units of traffic and there are 3 transponders each of a capacity of 13, in accordance with the present invention; and
FIG. 6 is a TDMA frame assignment sequence for the exemplary reduction of FIG. 5.
DETAILED DESCRIPTION
FIG. 1 illustrates a block diagram of a TDMA satellite communication subsystem arrangement 10 in accordance with the present invention. The subsystem arrangement 10 is shown as comprising a plurality of m receive ports 12 1 -12 m , each connected to a separate one of the m inputs of a first m by n microwave matrix switching means 14. A plurality of n transponders 16 1 -16 n , where n≦m, are connected at their inputs to a separate one of the n outputs of m by n switching means 14 and at their outputs to a separate one of the n inputs of a second n by m microwave matrix switching means 18. The m outputs of switching means 18 are each, in turn, connected to a separate one of a plurality of m transmit ports 20 1 -20 m . A switch controller 22 provides control signals on buses 23 and 24 to a first and second switching means 14 and 18, respectively, to cause the appropriate concurrent interconnection of the appropriate ones of the m receive ports 12 1 -12 m and m transmit ports 20 1 -20.sub. m to the inputs and outputs, respectively, of transponders 16 1 -16 m in accordance with a repetitive TDMA slot assignment sequence stored in a memory 26. The time slot assignment memory can be updated, as appropriate, by a telemetry link (not shown) to provide a different TDMA sequence whenever changes in terrestrial traffic patterns among the m spot beam footprints arise. In each case, an efficient switching sequence is stored in memory 26.
In accordance with the present invention, transponders 16 1 -16 n can advantageously be identical transponders of a suitable type which are commercially available. Similarly, first and second switching means 14 and 18, switch controller 22 and memory 26 can comprise any suitable arrangement which is commercially available. Each of the m receive and transmit ports will be hereinafter considered to include circuitry such as, for example, antenna means, etc. capable of receiving signals from a separate one of the m remote and spaced-apart ground areas and delivering such signals in proper form via first switching means 14 to the interconnected transponders 16 1 -16 n , and for appropriately transmitting the signals from transponders 16 1 -16 n delivered via second switching means 18 to be appropriately coupled transmitting ports 20 1 -20 m for concurrent transmission to n separate ones of the m ground areas, respectively.
FIG. 2 is a block diagram of an alternative arrangement for the subsystem arrangement 10 shown in FIG. 1. In the alternative arrangement of FIG. 2, a plurality of p receive antenna elements 30 1 -30 p are each connected to a separate one of a plurality of p splitter circuits designated 32 1 -32 p . For the arrangement of FIG. 2, each receive antenna elements 30 1 -30 p is capable of intercepting signals from the m separated and spaced-apart ground areas and the elements 30 1 -30 p effectively are the elements of a phased array antenna. Each splitter circuit 32 1 -32 p is shown as comprising one input terminal connected to the associated receive antenna element 30 and a plurality of n output terminals 33 1 -33 n and functions to deliver a 1/n part of the input signal to each of the output terminals 33 1 -33 n .
The plurality of n output terminals 33 1 -33 n of each splitter circuit 32 are connected to the individual inputs of a plurality of n phase shifters 34 1 -34 n , respectively. More particularly, the output terminals 33 1 and 33 2 of each of splitter circuits 32 1 -32 p are connected to the inputs of phase shifters 34 1 and 34 2 , respectively, in the group of n phase shifters 34 1 -34 n associated with each of splitter circuit 32. The remaining output terminals 33 3 -33 n of each of splitter circuits 32 1 -32 p are similarly connected to phase shifters 34 3 -34 n , respectively, in the associated group of phase shifters 34. The outputs of the corresponding phase shifters 34 in each group of n phase shifters 34 1 -34 n are connected to separate inputs of a separate one of a plurality of n combiner circuits 36 1 -36 n . For example, the outputs from each phase shifters 34 1 in each group of phase shifters 34.sub. 1 -34 n associated with each of splitter circuits 32 1 -32 p is connected to a separate one of p inputs of combiner circuit 36 1 . Similarly, the output from each of the corresponding ones of phase shifters 34 2 -34 n is connected to a separate one of the p inputs of combiner circuits 36 2 -36 n , respectively. Combiner circuits 36 1 -36 n function to combine the p input signals from the interconnected phase shifters 34 and deliver the resultant combined signal to transponders 16 1 -16 n , respectively.
The output from each of transponders 16 1 -16 n is delivered to the input of a separate one of splitter circuits 38 1 -38 n . For example, the output of transponder 16 1 is delivered to the input of splitter circuit 38 1 , the output of transponder 16 2 is delivered to the input of splitter circuit 38 2 , etc. Each of splitter circuits 38 1 -38 n have a single input from the associated transponder 16 and a plurality of p output terminals 39 1 -39 n and function to deliver 1/n part of the input signal from the associated transponder 16 to each of the n output terminals 39.
The transmit antenna is shown as comprising a plurality of p antenna elements, designated 44 1 -44 p , which effectively form a phased antenna array wherein each element 44 is capable of transmitting signals to any one of the m spaced-apart remote ground areas (not shown). Each one of the transmit antenna elements 44 1 -44 p is connected to the output of a separate one of a plurality of p combiner circuits 42 1 -42 p . Each combiner circuit 42 also includes a plurality of n input terminals 41 1 -41 n which terminals are connected to the outputs of a separate group of n phase shifters 40 1 -40 n , respectively, the combiner circuit functioning to combine the input signals from phase shifters 40 1 -40 n of the associated group of phase shifters into a single output signal to the associated antenna element 44. The outputs 39 1 -39 n of each of splitter circuits 38 1 -38 n are connected to separate corresponding ones of the phase shifters 40 in each group of n phase shifters associated with combiner circuits 42 1 -42 p . For example, the output terminals 39 1 -39 n of splitter circuit 38 1 are connected to separate ones of the corresponding phase shifters 40 1 in each of the groups of phase shifters 40 1 -40 n associated with combiner circuits 42 1 -42 p .
A phase controller 46 generates a sequence of separate concurrent control signals to (a) corresponding ones of phase shifters 34 1 -34 n via a bus 47, and (b) corresponding ones of phase shifters 40 1 -40 n via a bus 48. The sequence of the control signals to each of the corresponding ones of the phase shifters 34 and 40 in each group of phase shifters is generated from a predetermined TDMA slot assignment sequence stored in a TDMA slot assignment memory 26. As stated hereinbefore, the stored sequence can be updated via a telemetry link (not shown) to maintain efficiency of transponder utilization as terrestrial traffic patterns change.
As is well known in the art, a TDMA frame consists of a plurality of sequential time slots, each time slot representing one unit of traffic to be exchanged between a transmitting and a receiving ground area or station assigned thereto. The time slots in each frame sequence are selectively assigned to various paired transmitting and receiving ground area or station combinations dependent on the traffic requirement therebetween. Since each transponder 16 is capable of handling a separate repetitive frame sequence, n such separate frame sequences can be concurrently processed in the arrangements of FIGS. 1 and 2 to accommodate the nonuniform traffic requirements between the m remote and spaced-apart ground areas. The operation of FIGS. 1 and 2 will be described after a method for deriving a TDMA slot arrangement sequence is developed.
Since n≦m, a TDMA slot assignment sequence must be predetermined which will permit only n of the m ground areas to simultaneously transmit one unit of traffic via the arrangements of either FIG. 1 or 2 to n destination ground areas and still accommodate the nonuniform traffic requirements between all ground areas. This predetermined TDMA slot sequence is then stored in memory 26 and all ground stations and the FIGS. 1 and 2 arrangements are frame synchronized by any suitable technique known in the art.
To enable frequency reuse via a multibeam satellite system employing n identical transponders 16 1 -16 n such that all transponders 16 are used at maximum efficiency and a uniform grade of service is provided over the service area, the present invention uses a generalization upon the scanning beam approach and a TDMA slot assignment sequence will now be developed to better understand the operation of the arrangements of FIGS. 1 and 2.
In the arrangements of FIGS. 1 and 2, a satellite employing n identical wideband transponders are shown, each of which will be considered to have a capacity or throughput of C units of traffic per frame. The parameters of the satellite antenna 12 and 20 of FIG. 1 or 30 and 44 of FIG. 2 and the resulting beam width determine the number m of distinct footprints or ground areas needed to provide service anywhere throughout the required service area.
The system traffic can be represented by a matrix [t ij ] as shown: ##EQU1## the element t ij represents the traffic originating in ground area i and destined for somewhere in ground area j. Each footprint might contain several ground stations, so t ij represents the sum of the traffic from all stations within ground area i which is directed to stations within ground area j.
It is to be understood that it is not necessary that the traffic matrix be symmetric and that a loop-back feature is possible. For example, it is not required that t ij =t ji or that t ii =0 but it is understood that t ij ≧0.
Two requirements must be imposed on the traffic matrix [t ij ]. First, since the total capacity of the satellite is equal to nC (n transponders 16 1 -16 n each of capacity C), it is required that: ##EQU2## The second requirement is that the traffic originating from or destined for a particular ground area should not exceed the capacity of one transponder 16, i.e., ##EQU3##
The transponders 16 1 -16 n are utilized with 100 percent efficiency when equation (2) is satisfied as an equality. This equation may be interpreted as establishing the minimum number n of transponders required. Conditions (3) and (4) are necessary because no two transponders can be connected to a common spot beam, either up-link or down-link, on a noninterfering basis.
If the total offered traffic equals the sum of the transponder capacities, there is the potential for 100 percent utilization. The discussion which follows will show that it is possible, in accordance with the present invention, to interconnect the various up-link beams, transponders, and down-link beams such that this is achieved. Maximum utilization is done on a time division basis by enabling each of the n transponders 16 1 -6 n to access any of the m possible receive (up-link) beam signals, received by receive ports 12 1 -12 m of FIG. 1 or antenna elements 30 1 -30 p and appearing at the output of phase shifters 34 in FIG. 2, and any of the m possible transmit (down-link) beam signals to the m ground areas transmitted by transmit ports 20 1 -20 m of FIG. 1 or antenna elements 44 1 -44 p associated with phase shifters 40 of FIG. 2.
To achieve such assignment it must be understood that, by definition, a diagonal of a matrix [t ij ] is a K-tuple D={d 1 , d 2 , . . . , d k } where each member is a nonzero element of the matrix and no two elements appear in the same row or same column of the matrix. The length of the diagonal is K, where K is the number of elements, and the diagonal is said to cover the K rows and K columns from which the elements are taken. It can be proven that in a traffic matrix [t ij ] for which ##EQU4## and for which no row or column sum exceeds C, a diagonal of length n exists which covers all rows and columns which sum to C exactly, if any. This latter provable statement will hereinafter be referred to as the theorem. For convenience it will be assumed that the elements t ij of the traffic matrix are integers, representing the traffic as multiples of some basic unit such as, for example, one voice channel.
Traffic shall be assigned, in accordance with the present technique, to the various transponders 16 1 -16 n as follows: Let the TDMA frame sequence consist of C time slots, each representing one unit of traffic. There are n such frame sequences, one belonging to each of the n transponders. In the traffic matrix [t ij ], select a diagonal of length n from matrix T which covers all rows and columns summing to C, if any. The theorem guarantees this is always possible. From these n diagonal elements extract one unit of traffic from each and assign one unit of each of the n transponders 16 1 -16 n . Since the traffic assigned to the transponders 16 1 -16 n for this time slot originates from different up-link beams and are directed to different down-link beams, the traffic has been assigned on a noninterfering basis.
Since n units of traffic have been removed from the matrix, the reduced matrix has a total traffic of nC-n=n(C-1) units. Furthermore, each transponder 16 has C-1 units of traffic carrying capacity left, and no row or column of the reduced matrix sums to more than C-1. The latter is true because every row and column which summed to C in the original matrix has had one unit of traffic removed because of the way the diagonal was constructed.
At this stage, the same situation occurs as was started with except that C-1 replaces C. By the same technique, another n units of traffic are assigned to the next time slot for each of transponders 16 1 -16 n and the result is a matrix having traffic remaining equal to n(C-2) in which no row or column sums to more than C-2. Each of transponders 16 1 -16 n has then C-2 time slots unallocated. Hence, this procedure is repeated until all transponder time slots are used and no traffic remains unallocated. Thus the nonuniform demands of a traffic matrix can be met by n identical transponders each operating at 100 percent utilization efficiency.
An example of a TDMA slot assignment sequence is shown in FIGS. 3 and 4, which sequence is drawn for m=3 remote spaced-apart ground areas, n=2 transponders, and C=10 time slots per frame. Shown in FIG. 3 are the stages in the matrix reduction in accordance with the hereinbefore described steps where diagonal elements chosen are circled and rows or columns which sum to C or the reduced value of C are marked with an asterisk. FIG. 4 illustrates the resulting TDMA frame sequences for transponders 1 and 2 obtained from the matrix reduction stages of FIG. 3. In FIG. 3 the predetermined nonuniform traffic requirements between all combinations of the three remote spaced-apart ground areas are shown in the matrix at the upper left hand corner and designated (a).
In accordance with the hereinabove described procedure, row 1 is the only row which sums to C, or 10, and, therefore, one unit of traffic will be arbitrarily assigned therefrom to time slot 1 of, for example, transponder 1. Although it is shown in FIG. 3 that one unit will be chosen from the five units of traffic needed between ground stations in area 1, it is to be understood that any of the one traffic units required between ground stations in area 1 and area 2 or four traffic units required between ground stations in area 1 and area 3 could have alternatively been chosen since none of the columns also totalled to the value C, or 10. However, having chosen the matrix element from which a traffic unit is to be extracted, the second or n th unit of traffic will be obtained from a diagonal element. In matrix (a) of FIG. 3 this diagonal element must come from one of the elements not forming row 1 or column 1 from which the first traffic unit was extracted. As is shown, a traffic unit between ground stations in area 2 and 3 was selected for assignment to transponder 2, although any one of the other three diagonal elements could have been used to extract such traffic unit since they were all nonzero elements.
A consideration which may be used, although certainly not mandatory, is to choose traffic elements from the element of the row and column having the highest combined value. For example, in matrix (a) of FIG. 3, once row 1 was selected the element in column 1 was used to extract the traffic unit because the combined traffic demands of row 1 and column 1 totalled 19 which is higher than the combined totals of row 1 and either one of columns 2 or 3.
Since one traffic unit was extracted from matrix (a) the resulting matrix is shown in matrix (b) of FIG. 3. The process of extracting n, or 2, more units of traffic is similarly performed as described above for matrix (a) except that rows or columns totalling C-1, or 9, will be chosen. The procedure is repeated through matrices (c) to (j) until no traffic requirements remain unassigned, as shown in matrix (k) of FIG. 3. The selected traffic unit sequence shown in matrices (a) to (j) of FIG. 3 can be directly correlated to the TDMA slot assignment sequence for time slots 1-10 of transponders 1 and 2 shown in FIG. 4, where the numbers in each time slot for each transponder correspond to the up-link and down-link service regions interconnected by that transponder for that time slot.
It must be understood that although the method described was for a matrix for which equation (2) was satisfied as an equality (i.e., T=nC), it also applies to a matrix for which T≦nC, because such a matrix can always be padded with dummy traffic until T=nC. The assignments corresponding to the dummy traffic can be ignored, and simply reflect the fact that the available transponder capacity exceeds the demand.
The assignments are not unique and it may be possible to extract more than one unit of capacity per diagonal element at a time. This is desirable from a practical point of view as it minimizes the number of times the switches 14 and 18 of FIG. 1 or the phase shifters 34 and 40 of FIG. 2 have to be reconfigured during one frame period. To achieve this, it seems desirable to choose the n diagonal elements from large elements in the rows and columns with the largest sums, if possible. The maximum traffic extractable, however, is t=min (t 1 , t 2 ) where t 1 =smallest element on the diagonal and C-t 2 is the largest row or column sum among the rows and columns not covered by the diagonals.
As an example consider the matrix below with m=4, n=3 and C=13;
______________________________________Down-link beam j t.sub.ij 1 2 3 4 R.sub.i______________________________________Up-link 1 3 6 2 1 12beam 2 6 4 0 0 10i 3 0 1 6 2 9 4 2 0 2 4 8 S.sub.j 11 11 10 7 39 = T______________________________________
FIG. 5 illustrates successive reductions of this matrix as the traffic is assigned to the three transponders. As in FIG. 3, the diagonal elements chosen are circled and the rows and columns which sum to the reduced value of C, if any, are marked with an asterisk. In FIG. 5, 6 units of traffic are available from the diagonals chosen in matrix (a) but only 5 units are selected therefrom since, as was stated hereinbefore, the maximum traffic extractable is the smaller of either t 1 , the smallest element on the diagonal, which equals 6 or C-t 2 , the largest capacity of the row or column of the rows or columns not covered by the diagonal elements chose, which equals 13-8 or 5 and is here determinative. The corresponding traffic assignments to each of the three transponders is shown in FIG. 6 and requires but six changes in the switching means 14 and 18 configuration of FIG. 1 or phase shifters 34 and 40 of FIG. 2.
The traffic assignments once determined as shown for example in either FIGS. 4 or 6 are stored in TDMA slot assignment memory 26 in the arrangements of either FIGS. 1 or 2 prior to the system being turned on. It is to be understood that such traffic assignments can be subsequently changed via telemetry signals (not shown) to accommodate traffic changes or transponder failure.
In operation, all ground stations and the arrangements of FIGS. 1 and 2 are first frame synchronized. Once synchronized, the various ground stations transmit bursts of information in their assigned time slots. In the arrangement of FIG. 1 switch controller 22 concurrently transmits control signals on buses 23 and 24 to switching means 14 and 18, respectively, to connect the concurrently received n bursts of information at n of the m receive ports 12 through the correct predetermined transponders 16 1 -16 n for retransmission via the correct n of m transmit ports 20 in accordance with the frame sequence stored in memory 26.
In the arrangement of FIG. 2, the n bursts of information from n separate directions are received by each of the receive antenna elements 30 1 -30 p . The signals received at each element 30 are split into n equal parts by an associated splitter 32 and applied to separate ones of associated phase shifters 34 1 -34 n . Phase controller 46, in response to the frame sequences stored in memory 26 transmits separate control signals on bus 47 to each group of corresponding phase shifters 34 1 , 34 2 , . . . , 34 n in the p groups of phase shifters to match the phase thereof with a separate one of the n signal directions concurrently received in a manner well known in the art. The corresponding phase shifters in each group of phase shifters 34 1 -34 n , therefore, effectively pass the same one of n signals received by receive elements 30 1 -30 p to the associated combiner 36 and then to the transponder 16 associated therewith in accordance with the stored frame sequences. Phase controller 46 similarly transmits separate control signals on bus 48 to corresponding phase shifters 40 in the p groups of phase shifters 40 1 -40 n to apply the proper phase to each signal from the associated transponder 16 to cause transmit antenna elements 44 1 -44 p to transmit the signals in the proper directions to the destined ground stations in accordance with the n stored frame sequences.
Although the system described has been presented in terms of subdividing the transponder capacity by time division, it is applicable to any other method of subdividing the transponder capacity, e.g., by frequency division or a combination of time and frequency division. In a frequency division system the smallest subdivision unit of capacity would usually be larger than for a time division system and transponder linearity would be an important consideration as far as crosstalk is concerned. The TDMA system concept presented hereinbefore can be seen to employ n multiple scanning beams affording both the wide coverage associated with area beams and the high antenna gains of spot beams. High capacity is achieved by means of multiple spot beams and frequency reuse with all transponders 16 being able to be identical and occupy the entire bandwidth. By appropriate time division interconnection between the satellite transponders 16 and the spot beam antennas, high transponder utilization efficiency is achieved for the various nonuniform traffic requirements of the system's ground stations.
It is to be understood that the abovedescribed embodiments are simply illustrative of the principles of the invention. Various other modifications and changes may be made by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.
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A technique is disclosed for sharing a fixed number of identical transponders among a same or greater number of input and output signaling directions by rapidly scanning each transponder over appropriately defined group pairs of the input and output directions. The apparatus comprises n transponders having input and output terminals which are selectively and separately scanned over a plurality of m input and output signaling directions, respectively, by scanning means under the control of a controller. The scanning means can comprise separate m × n input and output matrix switches or a separate selectively changeable phase shifter at each antenna element which is connected to a summing and dividing means at the input and output terminal, respectively, of the associated transponder. An efficient TDMA slot assignment technique is also disclosed which covers nonuniform traffic requirements.
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FIELD OF THE INVENTION
The present invention is in the field of human medicine, particularly in the treatment of obesity and disorders associated with obesity. Most specifically, the invention relates to anti-obesity proteins that, when administered to a patient, regulate fat tissue.
BACKGROUND OF THE INVENTION
Obesity, and especially upper body obesity, is a common and very serious public health problem in the United States and throughout the world. According to recent statistics, more than 25% of the United States population and 27% of the Canadian population are over weight. Kuczmarski, Amer. J. of Clin. Nut. 55: 495S-502S (1992); Reeder et. al., Can. Med,. Ass. J., 23:226-233 (1992). Upper body obesity is the strongest risk factor known for type II diabetes mellitus, and is a strong risk factor for cardiovascular disease and cancer as well. Recent estimates for the medical cost of obesity are $150,000,000,000 world wide. The problem has become serious enough that the surgeon general has begun an initiative to combat the ever increasing adiposity rampant in American society.
Much of this obesity induced pathology can be attributed to the strong association with dyslipidemia, hypertension, and insulin resistance. Many studies have demonstrated that reduction in obesity by diet and exercise reduces these risk factors dramatically. Unfortunately these treatments are largely unsuccessful with a failure rate reaching 95%. This failure may be due to the fact that the condition is strongly associated with genetically inherited factors that contribute to increased appetite, preference for highly caloric foods, reduced physical activity, and increased lipogenic metabolism. This indicates that people inheriting these genetic traits are prone to becoming obese regardless of their efforts to combat the condition. Therefore, a new pharmacological agent that can correct this adiposity handicap and allow the physician to successfully treat obese patients in spite of their genetic inheritance is needed.
The ob/ob mouse is a model of obesity and diabetes that is known to carry an autosomal recessive trait linked to a mutation in the sixth chromosome. Recently, Yiying Zhang and co-workers published the positional cloning of the mouse gene linked with this condition. Yiying Zhang et al. Nature 372: 425-32 (1994). This report disclosed a gene coding for a 167 amino acid protein with a 21 amino acid signal peptide that is exclusively expressed in adipose tissue. The report continues to disclose that a mutation resulting in the conversion of a codon for arginine at position 105 to a stop codon results in the expression of a truncated protein, which presumably is inactive.
Physiologists have postulated for years that, when a mammal overeats, the resulting excess fat signals to the brain that the body is obese which, in turn, causes the body to eat less and burn more fuel. G. R. Hervey, Nature 227: 629-631 (1969). This "feedback" model is supported by parabiotic experiments that implicate a circulating hormone controlling adiposity. Based on this model, the protein, which is apparently encoded by the ob gene, is now speculated to be an adiposity regulating hormone.
Pharmacological agents that are biologically active and mimic the activity of this protein are useful to help patients regulate their appetite and metabolism and thereby control their adiposity. Until the present invention, such a pharmacological agent was unknown.
The present invention provides biologically active anti-obesity proteins. Such agents therefore allow patients to overcome their obesity handicap and live normal lives with a more normalized risk for type II diabetes, cardiovascular disease and cancer.
SUMMARY OF INVENTION
The present invention is directed to a biologically active anti-obesity protein of the Formula (I): ##STR1## wherein:
A is SEQ ID NO: 1; and
B is SEQ ID NO: 2.
The invention further provides a method of treating obesity, which comprises administering to a mammal in need thereof a protein of the Formula (I).
The invention further provides a pharmaceutical formulation, which comprises a protein of the Formula (I) together with one or more pharmaceutical acceptable diluents, carriers or excipients therefor.
DETAILED DESCRIPTION
For purposes of the present invention, as disclosed and claimed herein, the following terms and abbreviations are defined as follows:
Base pair (bp)--refers to DNA or RNA. The abbreviations A,C,G, and T correspond to the 5'-monophosphate forms of the nucleotides (deoxy)adenine, (deoxy)cytidine, (deoxy)guanine, and (deoxy)thymine, respectively, when they occur in DNA molecules. The abbreviations U,C,G, and T correspond to the 5'-monophosphate forms of the nucleosides uracil, cytidine, guanine, and thymine, respectively when they occur in RNA molecules. In double stranded DNA, base pair may refer to a partnership of A with T or C with G. In a DNA/RNA heteroduplex, base pair may refer to a partnership of T with U or C with G.
DNA--Deoyxribonucleic acid.
mRNA--messenger RNA.
Plasmid--an extrachromosomal self-replicating genetic element.
Reading frame--the nucleotide sequence from which translation occurs "read" in triplets by the translational apparatus of tRNA, ribosomes and associated factors, each triplet corresponding to a particular amino acid. Because each triplet is distinct and of the same length, the coding sequence must be a multiple of three. A base pair insertion or deletion (termed a frameshift mutation) may result in two different proteins being coded for by the same DNA segment. To insure against this, the triplet codons corresponding to the desired polypeptide must be aligned in multiples of three from the initiation codon, i.e. the correct "reading frame" must be maintained.
Recombinant DNA Cloning Vector--any autonomously replicating agent including, but not limited to, plasmids and phages, comprising a DNA molecule to which one or more additional DNA segments can or have been added.
Recombinant DNA Expression Vector--any recombinant DNA cloning vector in which a promoter has been incorporated.
Replicon--A DNA sequence that controls and allows for autonomous replication of a plasmid or other vector.
RNA--ribonucleic acid.
RP-HPLC--an abbreviation for reversed-phase high performance liquid chromatography.
Transcription--the process whereby information contained in a nucleotide sequence of DNA is transferred to a complementary RNA sequence.
Translation--the process whereby the genetic information of messenger RNA is used to specify and direct the synthesis of a polypeptide chain.
Tris--an abbreviation for tris(hydroxymethyl)aminomethane.
Treating--describes the management and care of a patient for the purpose of combating the disease, condition, or disorder and includes the administration of a compound of present invention to prevent the onset of the symptoms or complications, alleviating the symptoms or complications, or eliminating the disease, condition, or disorder. Treating obesity therefor includes the inhibition of food intake, the inhibition of weight gain, and inducing weight loss in patients in need thereof.
Vector--a replicon used for the transformation of cells in gene manipulation bearing polynucleotide sequences corresponding to appropriate protein molecules which, when combined with appropriate control sequences, confer specific properties on the host cell to be transformed. Plasmids, viruses, and bacteriophage are suitable vectors, since they are replicons in their own right. Artificial vectors are constructed by cutting and joining DNA molecules from different sources using restriction enzymes and ligases. Vectors include Recombinant DNA cloning vectors and Recombinant DNA expression vectors.
X-gal--an abbreviation for 5-bromo-4-chloro-3-idolyl beta-D-galactoside.
SEQ ID NO: 1 refers to the sequence set forth in the sequence listing and means an amino acid sequence of the formula: ##STR2## wherein:
Xaa at position 4 of SEQ ID NO: 1 is Gln or Glu;
Xaa at position 7 of SEQ ID NO: 1 is Gln or Glu;
Xaa at position 22 of SEQ ID NO: 1 is Gln, Asn, or Asp;
Xaa at position 27 of SEQ ID NO: 1 is Thr or Ala;
Xaa at position 28 of SEQ ID NO: 1 is Gln, Glu, or absent;
Xaa at position 34 of SEQ ID NO: 1 is Gln or Glu;
Xaa at position 54 of SEQ ID NO: 1 is Met, methionine sulfoxide, Leu, Ile, Val, Ala, or Gly;
Xaa at position 56 of SEQ ID NO: 1 is Gln or Glu;
Xaa at position 62 of SEQ ID NO: 1 is Gln or Glu;
Xaa at position 63 of SEQ ID NO: 1 is Gln or Glu;
Xaa at position 68 of SEQ ID NO: 1 is Met, methionine sulfoxide, Leu, Ile, Val, Ala, or Gly;
Xaa at position 72 of SEQ ID NO: 1 is Gln, Asn, or Asp;
Xaa at position 75 of SEQ ID NO: 1 is Gln or Glu;
Xaa at position 78 of SEQ ID NO: 1 is Gln, Asn, or Asp; and
Xaa at position 82 of SEQ ID NO: 1 is Gln, Asn, or Asp.
SEQ ID NO: 2 refers to the sequence set forth in the sequence listing and means an amino acid sequence of the formula: ##STR3##
wherein:
Xaa at position 4 of SEQ ID NO: 2 is Gln, Trp, Tyr, Phe, Ile, Val, or Leu;
Xaa at position 12 of SEQ ID NO: 2 is Asp or Glu;
Xaa at position 34 of SEQ ID NO: 2 is Gln or Glu;
Xaa at position 38 of SEQ ID NO: 2 is Gln or Glu;
Xaa at position 40 of SEQ ID NO: 2 is Met, methionine sulfoxide, Leu, Ile, Val, Ala, or Gly;
Xaa at position 42 of SEQ ID NO: 2 is Gln, Trp, Tyr, Phe, Ile, Val, or Leu; and
Xaa at position 43 of SEQ ID NO: 2 is Gln or Glu.
The amino acids abbreviations are accepted by the United States Patent and Trademark Office as set forth in 37 C.F.R. § 1.822 (b)(2) (1993). One skilled in the art would recognize that certain amino acids are prone to rearrangement. For example, Asp may rearrange to aspartimide and isoasparigine as described in I. Schon et al., Int. J. Peptide Protein Res. 14: 485-94 (1979) and references cited therein. These rearrangement derivatives are included within the scope of the present invention. Unless otherwise indicated the amino acids are in the L configuration.
As noted above the present invention provides a protein of the Formula (I): ##STR4## wherein:
A is SEQ ID NO: 1; and
B is SEQ ID NO: 2.
The preferred proteins of the present invention are those of Formula (i) wherein:
Xaa at position 4 of SEQ ID NO: 1 is Gln;
Xaa at position 7 of SEQ ID NO: 1 is Gln;
Xaa at position 22 of SEQ ID NO: 1 is Asn;
Xaa at position 27 of SEQ ID NO: 1 is Thr;
Xaa at position 28 of SEQ ID NO: 1 is Gln;
Xaa at position 34 of SEQ ID NO: 1 is Gln;
Xaa at position 54 of SEQ ID NO: 1 is Met;
Xaa at position 56 of SEQ ID NO: 1 is Gln;
Xaa at position 62 of SEQ ID NO: 1 is Gln;
Xaa at position 63 of SEQ ID NO: 1 is Gln;
Xaa at position 68 of SEQ ID NO: 1 is Met;
Xaa at position 72 of SEQ ID NO: 1 is Gln;
Xaa at position 75 of SEQ ID NO: 1 is Gln;
Xaa at position 78 of SEQ ID NO: 1 is Asn;
Xaa at position 82 of SEQ ID NO: 1 is Asn;
Xaa at position 4 of SEQ ID NO: 2 is Trp;
Xaa at position 12 of SEQ ID NO: 2 is Asp;
Xaa at position 34 of SEQ ID NO: 2 is Gln;
Xaa at position 38 of SEQ ID NO: 2 is Gln;
Xaa at position 40 of SEQ ID NO: 2 is Met;
Xaa at position 42 of SEQ ID NO: 2 is Trp; and
Xaa at position 43 of SEQ ID NO: 2 is Gln.
Yiying Zhang et al. in Nature 372: 425-32 (December 1994) report the cloning of the murine obese (ob) mouse gene and present mouse DNA and the naturally occurring amino acid sequence of the obesity protein for the mouse and human. This protein is speculated to be a hormone that is secreted by fat cells and controls body weight. The naturally occurring amino acid sequence of the obesity protein contains two cysteine residues; thus, providing a means to form a di-sulfide bond in the naturally occurring protein. The present invention is directed at replacing the single di-sulfide bond with a thioether bond. That is, cystine is chemically converted to lanthionine. The claimed lanthionine containing protein is more chemically stable. The protein is more bioavailable than the naturally occurring protein. Furthermore, the claimed peptide demonstrates greater serum stability and is therefore, longer acting. Thus, the present invention provides a biologically active protein, which is effective treatment for obesity.
The protein with unmodified cysteine residues is ordinarily prepared by recombinant DNA technology. Techniques for making substitutional mutations at predetermined sites in DNA having a known sequence are well known, for example M13 primer mutagenesis. The mutations that might be made in the DNA must not place the sequence out of reading frame and preferably will not create complementary regions that could produce secondary mRNA structure. See DeBoer et al., EP 75,444A (1983).
The compounds of the present invention may be prepared by substituting the cystine residue with lanthionine by dissolving the peptides in an aqueous solvent, preferably urea and adjusting the pH to about pH 11 to 12 with a base such as sodium hydroxide, potassium hydroxide or ammonium hydroxide at a temperature between about 4° C. to about 37° C. The temperature of the reaction is preferably 30° C. to 37° C. An acceptable protein concentration is from about 0.1 to 10 mg/mL. Preferably, the reaction is carried out at 1 mg/mL to 2 mg/mL. To aid in the formation of lanthionine and to improve the reaction yield, dithiothreitol (DTT) or other reducing agent may be added to the reaction mixture after adjusting the pH to about pH 11 to 12.
The claimed proteins may be purified from the reaction mixture by standard techniques appreciated in the art such as reversed phase chromatography, affinity chromatography, ion exchange chromatography, and size exclusion chromatography.
The protein with unmodified cysteine residues may be produced either by recombinant DNA technology or well known chemical procedures, such as solution or solid-phase peptide synthesis, or semi-synthesis in solution beginning with protein fragments coupled through conventional solution methods. The protein with unmodified cysteine residues may then be converted to the claimed protein by techniques taught herein. However, one skilled in the art would recognize that the claimed proteins can be produced directly by well known chemical procedures.
RECOMBINANT SYNTHESIS
The protein with unmodified cysteine residues may be produced by recombinant methods. Recombinant methods are preferred if a high yield is desired. The basic steps in the recombinant production of protein include:
a) construction of a synthetic or semi-synthetic (or isolation from natural sources) DNA encoding the protein with unmodified cysteine residues,
b) integrating the coding sequence into an expression vector in a manner suitable for the expression of the protein either alone or as a fusion protein,
c) transforming an appropriate eukaryotic or prokaryotic host cell with the expression vector, and
d) recovering and purifying the recombinantly produced protein.
1.a. Gene Construction
Synthetic genes, the in vitro or in vivo transcription and translation of which will result in the production of the protein may be constructed by techniques well known in the art. Owing to the natural degeneracy of the genetic code, the skilled artisan will recognize that a sizable yet definite number of DNA sequences may be constructed which encode the protein with unmodified cysteine residues. In the preferred practice of the invention, synthesis is achieved by recombinant DNA technology.
Methodology of synthetic gene construction is well known in the art. For example, see Brown, et al. (1979) Methods in Enzymology, Academic Press, N.Y., Vol. 68, pgs. 109-151. The DNA sequence corresponding to the synthetic protein gene may be generated using conventional DNA synthesizing apparatus such as the Applied Biosystems Model 380A or 380B DNA synthesizers (commercially available from Applied Biosystems, Inc., 850 Lincoln Center Drive, Foster City, Calif. 94404).
It may be desirable in some applications to modify the coding sequence of the protein so as to incorporate a convenient protease sensitive cleavage site, e.g., between the signal peptide and the structural protein facilitating the controlled excision of the signal peptide from the fusion protein construct.
The gene encoding the protein with unmodified cysteine residues may also be created by using polymerase chain reaction (PCR). The template can be a cDNA library (commercially available from CLONETECH or STRATAGENE) or mRNA isolated from human adipose tissue. Such methodologies are well known in the art Maniatis, et al. Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Press, Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y. (1989).
1.b. Direct Expression or Fusion Protein
The protein with unmodified cysteine residues may be made either by direct expression or as fusion protein comprising the protein followed by enzymatic or chemical cleavage. A variety of peptidases (e.g. trypsin) which cleave a polypeptide at specific sites or digest the peptides from the amino or carboxy termini (e.g. diaminopeptidase) of the peptide chain are known. Furthermore, particular chemicals (e.g. cyanogen bromide) will cleave a polypeptide chain at specific sites. The skilled artisan will appreciate the modifications necessary to the amino acid sequence (and synthetic or semi-synthetic coding sequence if recombinant means are employed) to incorporate site-specific internal cleavage sites. See e.g., Carter P., Site Specific Proteolysis of Fusion Proteins, Ch. 13 in Protein Purification: From Molecular Mechanisms to Large Scale Processes, American Chemical Soc., Washington, D.C. (1990).
1.c. Vector Construction
Construction of suitable vectors containing the desired coding and control sequences employ standard ligation techniques. Isolated plasmids or DNA fragments are cleaved, tailored, and religated in the form desired to form the plasmids required.
To effect the translation of the desired protein, one inserts the engineered synthetic DNA sequence into any of a plethora of appropriate recombinant DNA expression vectors through the use of appropriate restriction endonucleases. A synthetic coding sequence is designed to possess restriction endonuclease cleavage sites at either end of the transcript to facilitate isolation from and integration into these expression and amplification and expression plasmids. The isolated cDNA coding sequence may be readily modified by the use of synthetic linkers to facilitate the incorporation of this sequence into the desired cloning vectors by techniques well known in the art. The particular endonucleases employed will be dictated by the restriction endonuclease cleavage pattern of the parent expression vector to be employed. The choice of restriction sites are chosen so as to properly orient the coding sequence with control sequences to achieve proper in-frame reading and expression of the protein.
In general, plasmid vectors containing promoters and control sequences which are derived from species compatible with the host cell are used with these hosts. The vector ordinarily carries a replication site as well as marker sequences which are capable of providing phenotypic selection in transformed cells. For example, E. coli is typically transformed using pBR322, a plasmid derived from an E. coli species (Bolivar, et al., Gene 2: 95 (1977)). Plasmid pBR322 contains genes for ampicillin and tetracycline resistance and thus provides easy means for identifying transformed cells. The pBR322 plasmid, or other microbial plasmid must also contain or be modified to contain promoters and other control elements commonly used in recombinant DNA technology.
The desired coding sequence is inserted into an expression vector in the proper orientation to be transcribed from a promoter and ribosome binding site, both of which should be functional in the host cell in which the protein is to be expressed. An example of such an expression vector is a plasmid described in Belagaje et al., U.S. Pat. No. 5,304,493, the teachings of which are herein incorporated by reference. The gene encoding A-C-B proinsulin described in U.S. Pat. No. 5,304,493 can be removed from the plasmid pRB182 with restriction enzymes NdeI and BamHI. The genes encoding the protein with unmodified cysteine residues can be inserted into the plasmid backbone on a NdeI/BamHI restriction fragment cassette.
1.d. Procaryotic Expression
In general, procaryotes are used for cloning of DNA sequences in constructing the vectors useful in the invention. For example, E. coli K12 strain 294 (ATCC No. 31446) is particularly useful. Other microbial strains which may be used include E. coli B and E. coli X1776 (ATCC No. 31537). These examples are illustrative rather than limiting.
Prokaryotes also are used for expression. The aforementioned strains, as well as E. coli W3110 (prototrophic, ATCC No. 27325), bacilli such as Bacillus subtilis, and other enterobacteriaceae such as Salmonella typhimurium or Serratia marcescans, and various pseudomonas species may be used. Promoters suitable for use with prokaryotic hosts include the β-lactamase (vector pGX2907 [ATCC 39344] contains the replicon and β-lactamase gene) and lactose promoter systems (Chang et al., Nature, 275:615 (1978); and Goeddel et al., Nature 281:544 (1979)), alkaline phosphatase, the tryptophan (trp) promoter system (vector pATH1 [ATCC 37695] is designed to facilitate expression of an open reading frame as a trpE fusion protein under control of the trp promoter) and hybrid promoters such as the tac promoter (isolatable from plasmid pDR540 ATCC-37282). However, other functional bacterial promoters, whose nucleotide sequences are generally known, enable one of skill in the art to ligate them to DNA encoding the protein using linkers or adaptors to supply any required restriction sites. Promoters for use in bacterial systems also will contain a Shine-Dalgarno sequence operably linked to the DNA encoding protein.
1.e. Eucaryotic Expression
The protein with unmodified cysteine residues may be recombinantly produced in eukaryotic expression systems. Preferred promoters controlling transcription in mammalian host cells may be obtained from various sources, for example, the genomes of viruses such as: polyoma, Simian Virus 40 (SV40), adenovirus, retroviruses, hepatitis-B virus and most preferably cytomegalovirus, or from heterologous mammalian promoters, e.g. β-actin promoter. The early and late promoters of the SV40 virus are conveniently obtained as an SV40 restriction fragment which also contains the SV40 viral origin of replication. Fiers, et al., Nature, 273:113 (1978). The entire SV40 genome may be obtained from plasmid pBRSV, ATCC 45019. The immediate early promoter of the human cytomegalovirus may be obtained from plasmid pCMBβ (ATCC 77177). Of course, promoters from the host cell or related species also are useful herein.
Transcription of a DNA encoding the protein by higher eukaryotes is increased by inserting an enhancer sequence into the vector. Enhancers are cis-acting elements of DNA, usually about 10-300 bp, that act on a promoter to increase its transcription. Enhancers are relatively orientation and position independent having been found 5' (Laimins, L. et al., PNAS 78:993 (1981)) and 3' (Lusky, M. L., et al., Mol. Cell Bio. 3:1108 (1983)) to the transcription unit, within an intron (Banerji, J. L. et al., Cell 33:729 (1983)) as well as within the coding sequence itself (Osborne, T. F., et al., Mol. Cell Bio. 4:1293 (1984)). Many enhancer sequences are now known from mammalian genes (globin, RSV, SV40, EMC, elastase, albumin, alpha-fetoprotein and insulin). Typically, however, one will use an enhancer from a eukaryotic cell virus. Examples include the SV40 late enhancer, the cytomegalovirus early promoter enhancer, the polyoma enhancer on the late side of the replication origin, and adenovirus enhancers.
Expression vectors used in eukaryotic host cells (yeast, fungi, insect, plant, animal, human or nucleated cells from other multicellular organisms) will also contain sequences necessary for the termination of transcription which may affect mRNA expression. These regions are transcribed as polyadenylated segments in the untranslated portion of the mRNA encoding protein. The 3' untranslated regions also include transcription termination sites.
Expression vectors may contain a selection gene, also termed a selectable marker. Examples of suitable selectable markers for mammalian cells are dihydrofolate reductase (DHFR, which may be derived from the BglII/HindIII restriction fragment of pJOD-10 [ATCC 68815]), thymidine kinase (herpes simplex virus thymidine kinase is contained on the BamHI fragment of vP-5 clone [ATCC 2028]) or neomycin (G418) resistance genes (obtainable from pNN414 yeast artificial chromosome vector [ATCC 37682]). When such selectable markers are successfully transferred into a mammalian host cell, the transfected mammalian host cell can survive if placed under selective pressure. There are two widely used distinct categories of selective regimes. The first category is based on a cell's metabolism and the use of a mutant cell line which lacks the ability to grow without a supplemented media. Two examples are: CHO DHFR -- cells (ATCC CRL-9096) and mouse LTK -- cells (L-M(TK-) ATCC CCL-2.3). These cells lack the ability to grow without the addition of such nutrients as thymidine or hypoxanthine. Because these cells lack certain genes necessary for a complete nucleotide synthesis pathway, they cannot survive unless the missing nucleotides are provided in a supplemented media. An alternative to supplementing the media is to introduce an intact DHFR or TK gene into cells lacking the respective genes, thus altering their growth requirements. Individual cells which were not transformed with the DHFR or TK gene will not be capable of survival in non supplemented media.
The second category is dominant selection which refers to a selection scheme used in any cell type and does not require the use of a mutant cell line. These schemes typically use a drug to arrest growth of a host cell. Those cells which have a novel gene would express a protein conveying drug resistance and would survive the selection. Examples of such dominant selection use the drugs neomycin, Southern P. and Berg, P., J. Molec. Appl. Genet. 1: 327 (1982), mycophenolic acid, Mulligan, R. C. and Berg, P. Science 209:1422 (1980), or hygromycin, Sugden, B. et al., Mol Cell. Biol. 5:410-413 (1985). The three examples given above employ bacterial genes under eukaryotic control to convey resistance to the appropriate drug G418 or neomycin (geneticin), xgpt (mycophenolic acid) or hygromycin, respectively.
A preferred vector for eucaryotic expression is pRc/CMV. pRc/CMV is commercially available from Invitrogen Corporation, 3985 Sorrento Valley Blvd., San Diego, Calif. 92121. To confirm correct sequences in plasmids constructed, the ligation mixtures are used to transform E. coli K12 strain DH5a (ATCC 31446) and successful transformants selected by antibiotic resistance where appropriate. Plasmids from the transformants are prepared, analyzed by restriction and/or sequence by the method of Messing, et al., Nucleic Acids Res. 9:309 (1981).
Host cells may be transformed with the expression vectors of this invention and cultured in conventional nutrient media modified as is appropriate for inducing promoters, selecting transformants or amplifying genes. The culture conditions, such as temperature, pH and the like, are those previously used with the host cell selected for expression, and will be apparent to the ordinarily skilled artisan. The techniques of transforming cells with the aforementioned vectors are well known in the art and may be found in such general references as Maniatis, et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Press, Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y. (1989), or Current Protocols in Molecular Biology (1989) and supplements.
Preferred suitable host cells for expressing the vectors encoding the proteins in higher eukaryotes include: African green monkey kidney line cell line transformed by SV40 (COS-7, ATCC CRL-1651); transformed human primary embryonal kidney cell line 293, (Graham, F. L. et al., J. Gen Virol. 36:59-72 (1977), Virology 77:319-329, Virology 86:10-21); baby hamster kidney cells (BHK-21(C-13), ATCC CCL-10, Virology 16:147 (1962)); chinese hamster ovary cells CHO-DHFR -- (ATCC CRL-9096), mouse Sertoli cells (TM4, ATCC CRL-1715, Biol. Reprod. 23:243-250 (1980)); african green monkey kidney cells (VERO 76, ATCC CRL-1587); human cervical epitheloid carcinoma cells (HeLa, ATCC CCL-2); canine kidney cells (MDCK, ATCC CCL-34); buffalo rat liver cells (BRL 3A, ATCC CRL-1442); human diploid lung cells (WI-38, ATCC CCL-75); human hepatocellular carcinoma cells (Hep G2, ATCC HB-8065); and mouse mammary tumor cells (MMT 060562, ATCC CCL51).
1.f. Yeast Expression
In addition to prokaryotes, eukaryotic microbes such as yeast cultures may also be used. Saccharomyces cerevisiae, or common baker's yeast is the most commonly used eukaryotic microorganism, although a number of other strains are commonly available. For expression in Saccharomyces, the plasmid YRp7, for example, (ATCC-40053, Stinchcomb, et al., Nature 282:39 (1979); Kingsman et al., Gene 7:141 (1979); Tschemper et al., Gene 10:157 (1980)) is commonly used. This plasmid already contains the trp gene which provides a selection marker for a mutant strain of yeast lacking the ability to grow in tryptophan, for example ATCC no. 44076 or PEP4-1 (Jones, Genetics 85:12 (1977)).
Suitable promoting sequences for use with yeast hosts include the promoters for 3-phosphoglycerate kinase (found on plasmid pAP12BD ATCC 53231 and described in U.S. Pat. No. 4,935,350, Jun. 19, 1990) or other glycolytic enzymes such as enolase (found on plasmid pAC1 ATCC 39532), glyceraldehyde-3-phosphate dehydrogenase (derived from plasmid pHcGAPC1 ATCC 57090, 57091), zymomonas mobilis (U.S. Pat. No. 5,000,000 issued Mar. 19, 1991), hexokinase, pyruvate decarboxylase, phosphofructokinase, glucose-6-phosphate isomerase, 3-phosphoglycerate mutase, pyruvate kinase, triosephosphate isomerase, phosphoglucose isomerase, and glucokinase.
Other yeast promoters, which are inducible promoters having the additional advantage of transcription controlled by growth conditions, are the promoter regions for alcohol dehydrogenase 2, isocytochrome C, acid phosphatase, degradative enzymes associated with nitrogen metabolism, metallothionein (contained on plasmid vector pCL28XhoLHBPV ATCC 39475, U.S. Pat. No. 4,840,896), glyceraldehyde 3-phosphate dehydrogenase, and enzymes responsible for maltose and galactose (GAL1 found on plasmid pRY121 ATCC 37658) utilization. Suitable vectors and promoters for use in yeast expression are further described in R. Hitzeman et al., European Patent Publication No. 73,657A. Yeast enhancers such as the UAS Gal from Saccharomyces cerevisiae (found in conjunction with the CYC1 promoter on plasmid YEpsec--hI1beta ATCC 67024), also are advantageously used with yeast promoters.
The protein with unmodified cysteine residue refers to the protein translated off the ribosome. One skilled in the art would recognize that the cysteine can be converted to inter or intra molecular cystine by in vitro oxidation, or by cellular mechanisms.
The following examples and preparations are presented to further illustrate the preparation of the claimed proteins. The scope of the present invention is not to be construed as merely consisting of the following examples.
PREPARATION 1
A DNA sequence encoding the following protein sequence: ##STR5## is obtained using standard PCR methodology. A forward primer (5'-GG GG CAT ATG AGG GTA CCT ATC CAG AAA GTC CAG GAT GAC AC) SEQ ID. No: 4 and a reverse primer (5'-GG GG GGATC CTA TTA GCA CCC GGG AGA CAG GTC CAG CTG CCA CAA CAT) SEQ ID No: 5 is used to amplify sequences from a human fat cell library (commercially available from CLONETECH). The PCR product is cloned into PCR-Script (available from STRATAGENE) and sequenced.
PREPARATION 2
Vector Construction
A plasmid containing the DNA sequence encoding the desired protein is constructed to include NdeI and BamHI restriction sites. The plasmid carrying the cloned PCR product is digested with NdeI and BamHI restriction enzymes. The small˜450 bp fragment is gel-purified and ligated into the vector pRB182 from which the coding sequence for A-C-B proinsulin is deleted. The ligation products are transformed into E. coli DH10B (commercially available from GIBCO-BRL) and colonies growing on tryptone-yeast (DIFCO) plates supplemented with 10 μg/mL of tetracycline are analyzed. Plasmid DNA is isolated, digested with NdeI and BamHI and the resulting fragments are separated by agarose gel electrophoresis. Plasmids containing the expected˜450 bp NdeI to BamHI fragment are kept. E. coli B BL21 (DE3) (commercially available from NOVOGEN) are transformed with this second plasmid expression suitable for culture for protein production.
The techniques of transforming cells with the aforementioned vectors are well known in the art and may be found in such general references as Maniatis, et al. (1988) Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Press, Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y. or Current Protocols in Molecular Biology (1989) and supplements. The techniques involved in the transformation of E. coli cells used in the preferred practice of the invention as exemplified herein are well known in the art. The precise conditions under which the transformed E. coli cells are cultured is dependent on the nature of the E. coli host cell line and the expression or cloning vectors employed. For example, vectors which incorporate thermoinducible promoter-operator regions, such as the c1857 thermoinducible lambda-phage promoter-operator region, require a temperature shift from about 30 to about 40 degrees C. in the culture conditions so as to induce protein synthesis.
In the preferred embodiment of the invention E. coli K12 RV308 cells are employed as host cells but numerous other cell lines are available such as, but not limited to, E. coli K12 L201, L687, L693, L507, L640, L641, L695, L814 (E. coli B). The transformed host cells are then plated on appropriate media under the selective pressure of the antibiotic corresponding to the resistance gene present on the expression plasmid. The cultures are then incubated for a time and temperature appropriate to the host cell line employed.
Proteins which are expressed in high-level bacterial expression systems characteristically aggregate in granules or inclusion bodies which contain high levels of the overexpressed protein. Kreuger et al., in Protein Folding, Gierasch and King, eds., pgs 136-142 (1990), American Association for the Advancement of Science Publication No. 89-18S, Washington, D.C. Such protein aggregates must be solubilized to provide further purification and isolation of the desired protein product. Id.
Preferably, the present proteins are expressed as Met-Arg protein so that the expressed proteins may be readily converted to the protein with Cathepsin C. The purification of proteins is by techniques known in the art and includes reversed phase chromatography, affinity chromatography, ion exchange chromatography, and size exclusion.
The claimed proteins are prepared by dissolving the protein with unmodified cysteine residues in a urea solution (about 3 to about 8M, preferably 7M). The pH is raised to about pH 11 to about pH 12. The solution is allowed to incubate at the elevated pH at a temperature between about 4° C. to about 37° C. for between 4 and 72 hours. The protein may be treated with a reducing compound such as DTT. Two likely intermediates are of the Formula (II): ##STR6## wherein:
A is SEQ ID NO: 1; and
B is SEQ ID NO: 2.
These intermediates are unstable and quickly convert to the more stable lanthionine compounds of the Formula (I). However, one skilled in the art would recognize that depending on the conditions used and the reducing agent employed other intermediates are possible. This reaction is further illustrated in the following Example.
EXAMPLE 1
The pH of 1 mg/mL solution of cystine containing peptide of SEQ ID No: 3 is adjusted to pH 12 with NaOH and held at 37° C. The reaction is monitored with an SDS gel assay to measure non-reducible peptide. At the completion of the reaction, the lanthionine containing peptide is purified by reversed phase chromatography with an acetonitrile gradient.
The compounds of Formula (I) may exist, particularly when formulated, as dimers, trimers, tetramers, and other multimers. Such multimers are included within the scope of the present invention.
The present invention provides a method for treating obesity. The method comprises administering to the organism an effective amount of anti-obesity protein in a dose between about 1 and 1000 μg/kg. A preferred dose is from about 10 to 100 μg/kg of active compound. A typical daily dose for an adult human is from about 0.5 to 100 mg. In practicing this method, compounds of the Formula (I) can be administered in a single daily dose or in multiple doses per day. The treatment regime may require administration over extended periods of time. The amount per administered dose or the total amount administered will be determined by the physician and depend on such factors as the nature and severity of the disease, the age and general health of the patient and the tolerance of the patient to the compound.
The invention further provides pharmaceutical formulations comprising compounds of the Formula (I). The proteins, preferably in the form of a pharmaceutically acceptable salt, can be formulated for parenteral administration for the therapeutic or prophylactic treatment of obesity. For example, compounds of the Formula (I) can be admixed with conventional pharmaceutical carriers and excipients. The compositions comprising claimed proteins contain from about 0.1 to 90% by weight of the active protein, preferably in a soluble form, and more generally from about 10 to 30%. Furthermore, the present proteins may be administered alone or in combination with other anti-obesity agents or agents useful in treating diabetes.
For intravenous (i.v.) use, the protein is administered in commonly used intravenous fluid(s) and administered by infusion. Such fluids, for example, physiological saline, Ringer's solution or 5% dextrose solution can be used.
For intramuscular preparations, a sterile formulation, preferably a suitable soluble salt form of a protein of the Formula (I), for example the hydrochloride salt, can be dissolved and administered in a pharmaceutical diluent such as pyrogen-free water (distilled), physiological saline or 5% glucose solution. A suitable insoluble form of the compound may be prepared and administered as a suspension in an aqueous base or a pharmaceutically acceptable oil base, e.g. an ester of a long chain fatty acid such as ethyl oleate.
The ability of the present compounds to treat obesity is demonstrated in vivo as follows:
BIOLOGICAL TESTING FOR ANTI-OBESITY PROTEINS
Parabiotic experiments suggest that a protein is released by peripheral adipose tissue and that the protein is able to control body weight gain in normal, as well as obese mice. Therefore, the most closely related biological test is to inject the test article by any of several routes of administration (e.g. i.v., s.c., i.p., or by minipump or cannula) and then to monitor food and water consumption, body weight gain, plasma chemistry or hormones (glucose, insulin, ACTH, corticosterone, GH, T4) over various time periods. Suitable test animals include normal mice (ICR, etc.) and obese mice (ob/ob , Avy/a, KK-Ay, tubby, fat). The ob/ob mouse model of obesity and diabetes is generally accepted in the art as being indicative of the obesity condition. Controls for non-specific effects for these injections are done using vehicle with or without the active agent of similar composition in the same animal monitoring the same parameters or the active agent itself in animals that are thought to lack the receptor (db/db mice, fa/fa or cp/cp rats). Proteins demonstrating activity in these models will demonstrate similar activity in other mammals, particularly humans.
Since the target tissue is expected to be the hypothalamus where food intake and lipogenic state are regulated, a similar model is to inject the test article directly into the brain (e.g. i.c.v. injection via lateral or third ventricles, or directly into specific hypothalamic nuclei (e.g. arcuate, paraventricular, perifornical nuclei). The same parameters as above could be measured, or the release of neurotransmitters that are known to regulate feeding or metabolism could be monitored (e.g. NPY, galanin, norepinephrine, dopamine, β-endorphin release).
Similar studies are accomplished in vitro using isolated hypothalamic tissue in a perifusion or tissue bath system. In this situation, the release of neurotransmitters or electrophysiological changes is monitored.
The compounds are active in at least one of the above biological tests and are anti-obesity agents. As such, they are useful in treating obesity and those disorders implicated by obesity. However, the proteins are not only useful as therapeutic agents; one skilled in the art recognizes that the proteins are useful in the production of antibodies for diagnostic use and, as proteins, are useful as feed additives for animals. Furthermore, the compounds are useful for controlling weight for cosmetic purposes in mammals. A cosmetic purpose seeks to control the weight of a mammal to improve bodily appearance. The mammal is not necessarily obese. Such cosmetic use forms part of the present invention.
__________________________________________________________________________SEQUENCE LISTING(1) GENERAL INFORMATION:(iii) NUMBER OF SEQUENCES: 5(2) INFORMATION FOR SEQ ID NO:1:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 95 amino acids(B) TYPE: amino acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: protein(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 4(D) OTHER INFORMATION: /note= "Xaa at position 4 of SEQ IDNO. 1 is Gln or Glu;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 7(D) OTHER INFORMATION: /note= "Xaa at position 7 of SEQ IDNO. 1 is Gln or Glu;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 22(D) OTHER INFORMATION: /note= "Xaa at position 22 of SEQID NO. 1 is Gln, Asn or Asp;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 27(D) OTHER INFORMATION: /note= "Xaa at position 27 of SEQID NO. 1 is Thr or Ala;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 28(D) OTHER INFORMATION: /note= "Xaa at position 28 of SEQID NO. 1 is Gln, Glu or absent;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 34(D) OTHER INFORMATION: /note= "Xaa at position 34 of SEQID NO. is Gln or Glu;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 54(D) OTHER INFORMATION: /note= "Xaa at position 54 of SEQID NO. is Met, methionine sulfoxide, Leu, Ile, Val, Ala,or Gly;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 56(D) OTHER INFORMATION: /note= "Xaa at position 56 of SEQID NO. 1 is Gln or Glu;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 62(D) OTHER INFORMATION: /note= "Xaa at position 62 of SEQID NO. 1 is Gln or Glu;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 63(D) OTHER INFORMATION: /note= "Xaa at position 63 of SEQID NO. 1 is Gln or Glu;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 68(D) OTHER INFORMATION: /note= "Xaa at position 68 of SEQID NO. 1 is Met, methionine sulfoxide, Leu, Ile, Val,Ala or Gly;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 72(D) OTHER INFORMATION: /note= "Xaa at position 72 of SEQID NO. 1 is Gln, Asn, or Asp;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 75(D) OTHER INFORMATION: /note= "Xaa at position 75 of SEQID NO. 1 is Gln or Glu;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 78(D) OTHER INFORMATION: /note= "Xaa at position 78 of SEQID NO. 1 is Gln, Asn, or Asp;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 82(D) OTHER INFORMATION: /note= "Xaa at position 82 of SEQID NO. 1 is Gln, Asn, or Asp."(xi) SEQUENCE DESCRIPTION: SEQ ID NO:1:ValProIleXaaLysValXaaAspAspThrLysThrLeuIleLysThr151015IleValThrArgIleXaaAspIleSerHisXaaXaaSerValSerSer202530LysXaaLysValThrGlyLeuAspPheIleProGlyLeuHisProIle354045LeuThrLeuSerLysXaaAspXaaThrLeuAlaValTyrXaaXaaIle505560LeuThrSerXaaProSerArgXaaValIleXaaIleSerXaaAspLeu65707580GluXaaLeuArgAspLeuLeuHisValLeuAlaPheSerLysSer859095(2) INFORMATION FOR SEQ ID NO:2:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 49 amino acids(B) TYPE: amino acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: protein(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 4(D) OTHER INFORMATION: /note= "Xaa at poisition 4 of SEQID NO. 2 is Gln, Trp, Tyr, Phe, Ile, Val, or Leu;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 12(D) OTHER INFORMATION: /note= "Xaa at position 12 of SEQID NO. 2 is Asp or Glu;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 34(D) OTHER INFORMATION: /note= "Xaa at position 34 of SEQID NO. 2 is Gln or Glu;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 38(D) OTHER INFORMATION: /note= "Xaa at position 38 of SEQID NO. 2 is Gln or Glu;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 40(D) OTHER INFORMATION: /note= "Xaa at position 40 of SEQID NO. 2 is Met, methionine sulfoxide, Leu, Ile, Val,Ala, or Gly;"(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 42(D) OTHER INFORMATION: /note= "Xaa at position 42 of SEQID NO. 2 is Gln, Trp, Tyr, Phe, Ile, Val, or Leu; "(ix) FEATURE:(A) NAME/KEY: Modified-site(B) LOCATION: 43(D) OTHER INFORMATION: /note= "Xaa at position 43 of SEQID NO. 2 is Gln or Glu;"(xi) SEQUENCE DESCRIPTION: SEQ ID NO:2:HisLeuProXaaAlaSerGlyLeuGluThrLeuXaaSerLeuGlyGly151015ValLeuGluAlaSerGlyTyrSerThrGluValValAlaLeuSerArg202530LeuXaaGlySerLeuXaaAspXaaLeuXaaXaaLeuAspLeuSerPro354045Gly(2) INFORMATION FOR SEQ ID NO:3:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 146 amino acids(B) TYPE: amino acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: protein(xi) SEQUENCE DESCRIPTION: SEQ ID NO:3:ValProIleGlnLysValGlnAspAspThrLysThrLeuIleLysThr151015IleValThrArgIleAsnAspIleSerHisThrGlnSerValSerSer202530LysGlnLysValThrGlyLeuAspPheIleProGlyLeuHisProIle354045LeuThrLeuSerLysMetAspGlnThrLeuAlaValTyrGlnGlnIle505560LeuThrSerMetProSerArgAsnValIleGlnIleSerAsnAspLeu65707580GluAsnLeuArgAspLeuLeuHisValLeuAlaPheSerLysSerCys859095HisLeuProTrpAlaSerGlyLeuGluThrLeuAspSerLeuGlyGly100105110ValLeuGluAlaSerGlyTyrSerThrGluValValAlaLeuSerArg115120125LeuGlnGlySerLeuGlnAspMetLeuTrpGlnLeuAspLeuSerPro130135140GlyCys145(2) INFORMATION FOR SEQ ID NO:4:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 42 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: protein(xi) SEQUENCE DESCRIPTION: SEQ ID NO:4:GGGGCATATGAGGGTACCTATCCAGAAAGTCCAGGATGACAC42(2) INFORMATION FOR SEQ ID NO:5:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 48 base pairs(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: protein(xi) SEQUENCE DESCRIPTION: SEQ ID NO:5:GGGGGGATCCTATTAGCACCCGGGAGACAGGTCCAGCTGCCACAACAT48__________________________________________________________________________
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The present invention provides anti-obesity proteins, which when administered to a patient regulate fat tissue. Accordingly, such agents allow patients to overcome their obesity handicap and live normal lives with much reduced risk for type II diabetes, cardiovascular disease and cancer.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a drive system designed to transfer power from a power source onto a plurality of drivetrains.
2. Description of the Related Art
Many industrial drive system concepts are based on the distribution and transfer of power, originating from a power source onto several power consumers, which are positioned downstream of the power consumer. A significant area of application of such a drive system concept are roll mills. The power developed by a motor is transferred via drivetrains onto several working rolls. For that purpose, a transfer gearbox is connected ahead of the drivetrains. The transfer gearbox includes in its simplest form only several spur gears, which are positioned in a manner that allows the transfer of power onto the downstream positioned universal drivetrains in accordance to the ratio of the spur gears. The drivetrain can further include apparatuses for torque and speed amplification. Disturbances on the driven equipment cause an interruption of the torque transfer from the driving to the driven system, resulting in an unacceptable increase in torque. In roll mills, these types of disturbances manifest themselves as jams during the rolling process. The cause of such jams is primarily a result of a lamination of the rolling stock, the use of cold rolling stock, or a fracture of the roll. The reason for such an unacceptable increase in torque is the continued propulsion of the masses in spite of the disturbances on the driven side of the drivetrain. This manifests itself in a deformation of the drivetrain, which can lead to torsional fractures in extreme cases. In order to avoid such failures, as well as prevent the unacceptable torque increase, special and quickly separable safety couplings are available for the transfer of torque between two mechanical components on the same axis. An exemplification of such a coupling, including an overload safety device, designed to prevent excessive torque spikes, is published in the German paper DE-OS-29-23-902. The coupling includes at least one thin-walled sleeve, forming a wall of a ring-shaped chamber extending in axial direction. The ring-shaped chamber can be pressurized with a medium in order to elastically deform the sleeve in radial direction causing it to jam against the surface of an element onto which the coupling is mounted. Adjacent to the ring-shaped chamber are drillings, which are a part of a safety or coupling relief device. As a result of the relative motion between the surfaces and the actions of the relief device, the pressurized medium residing in the ring-shaped chamber can escape through the drillings, thus lowering the pressure inside the chamber.
To transfer a certain torque level, a certain surface pressure is required. For that purpose, oil is pumped into the chamber, which is needed to deform the respective machine components relative to one another. In this way, the coupling is adjusted to the desired torque capacity. If, during an overload condition, this torque is exceeded, the coupling slips. The maximum torque level that can be transmitted reduces because the effective, static friction coefficient transitions into the sliding friction coefficient. There is a relative motion in circumferential direction between the individual elements of the two machine components, which are jammed relative to one another. A shear disk mounted on one machine component shears off a shear valve, opening the connection to the ring-shaped chamber of the coupling. After shearing off the shearing valve (or valves), the pressurized oil can freely expand and the torque to be transmitted reduces to zero within a few milliseconds. Such couplings are placed in a sensible manner in areas of possible disturbances.
For an application in a roll mill, the safety coupling must be positioned near the rolls. This, however, is not always feasible, which is why such a safety coupling must be mounted either in every universal drivetrain or immediately ahead of every universal drivetrain. This disadvantage of such an arrangement of safety couplings in a drivetrain, especially in an application such as a roll mill, is the high cost, since every universal drivetrain or branch of a power take-off is assigned a safety coupling. Furthermore, there is a direct relationship between the size of the safety coupling and the torque to be transmitted. Higher torque levels require a larger diameter safety coupling, which is met by limitations as a result of the placement of the universal drivetrains or the individual power take-offs, as well as their center-line distances to one another.
SUMMARY OF THE INVENTION
The present invention provides a drive system of the type mentioned in the introduction, which avoids the disadvantages. An overload safety device for preventing a torque overload condition is cost-effective, easy to manufacture, as well as fast-responding. The overload safety device for preventing a torque overload condition is effective at torque levels that are only minimally above the maximum allowable torque. The magnitude of the maximum allowable torque to be transmitted is adjusted so that, if this torque is exceeded, the torque transmission can be quickly disrupted. Furthermore, the overload safety device designed to prevent a torque overload condition offers a rapid response time, i.e., a short period of time between the occurrence of an unacceptable high torque level and the interruption of the torque transmission.
The overload safety device is a cost-effective solution with respect to the construction and function, including only a small number of relatively simple components. The entire arrangement is characterized by low manufacturing and assembly costs, as well as by minimum effort required to reset the coupling after a triggering event, i.e., after an interruption of a torque transmission.
By placing the safety coupling--including a coupling body to frictionally engage two machine components and a relief mechanism--upstream from the transfer gear box, only one coupling is required to protect against a torque overload condition. The relief mechanism cannot be designed as described in German document DE-OS-29-23-902, but the relief mechanism must be designed to operate at a faster response time. This response time should correspond to a fraction of the natural frequency of the drive system in order to avoid deformations in the drivetrain. This is accomplished by use of an external relief method, i.e., by directly or indirectly controlled opening of the supply drillings. To disrupt the torque transfer at relatively low torque spikes on the individual power take-offs, especially the universal drivetrains, an appropriate relief mechanism is provided, which is connected to a torque sensing/acquisition device assigned to every universal drivetrain, and/or a device to capture a value proportional to the expected torque value, and/or a device to capture a disturbance value originating in the vicinity of the machine and affecting the operation of the machine.
The safety coupling is a remote operated coupling, which is triggered in response to a predetermined value for the current torque value, and/or a characteristic value proportional to the torque, and/or the occurrence of a disturbance value. In terms of the triggering method, there are several possibilities that should be considered: sensing of the torque of each power take-off, especially of each universal drivetrain, and/or sensing of a value proportional to the torque on the individual power take-offs (for example: the roll forces, speed differences observed in a roll mill), and/or sensing of parameters of the materials to be processed which are indirectly proportional to the torque value (in roll mills--temperature and thickness of materials) and/or the capture of the disturbance value impacting the manufacturing process of the machine in a retroactive fashion (for example: vibration in the foundation).
The determined values can be compared to a not-to-be-exceeded command value in order to generate a signal to control the relief mechanism by use of a control device. A mechanical device is also feasible.
As far as the possibilities to trigger the relief mechanism, there are a plurality of possible variations. The relief mechanism includes, for example, a shear device to separate the shear valve, which keeps the pressurized medium from escaping from the ring-shaped chamber of the coupling. The shear device is mounted in a freely rotatable manner relative to the coupling body, including at least one thin-walled sleeve forming a wall of the pressurized, ring-shaped chamber. The mounting is designed so that the shear device is rotating together with the drivetrain nearly without difference in rotational speed in relation to the shear valves. The coupling between the relief mechanism and the speed-sensing/acquisition device of each universal drivetrain works on the basis that when the maximum allowable torque and/or a characteristic value, proportional to the maximum allowable torque is exceeded, or at the occurrence of a disturbance value, the shear device is reduced in speed. Because of the resulting rotational speed difference, the shear valves are sheared off in response to the relative circumferential motion difference between the shear device and the shear valves, causing a relief of the pressurized medium in the ring-shaped chamber. The force or torque transfer is therefore disrupted.
Another possibility is to include at least one machine element in the relief mechanism, including an explosive substance which, in the event of an overload condition, is triggered to explode, allowing the supply drilling to open. The explosive substances are either solid, liquid, or viscid substances or substance mixtures which, after ignition by sparks, flames, or impact, etc., rapidly release large amounts of compressible gases, causing destructive effects in its immediate surroundings. For the triggering and relief of the coupling and the storage of the explosive substance, there are at least two possibilities. The triggering can occur directly, i.e., the explosive substance is integrated directly in the sealing valves and ignited there. The triggering by the machine element carrying the explosive substance can occur indirectly, i.e., the relief mechanism includes a shear device. The explosive substance is applied to "connectors" and is activated at the site of the shear device.
The basic principle, according to this invention, is the placement of a cost effective safety coupling--designed to prevent a torque overload condition--and the design of the appropriate relief mechanism, which is a part of the safety coupling, into a drivetrain whereby the power generated by a power source is distributed onto multiple power consumers.
The shear device, designed in the form of a ring with oblong openings, partially encompasses the shear valves, which usually protrude only minimally above the outer periphery of the coupling body. Shear devices, especially, the shear disk, and the main body of the coupling should both be mounted on the same machine component. The braking or the stopping of the shear device can be accomplished in different ways. The use of a disc brake, drum brake, ratchet mechanism, or the application of systems with pre-loaded springs which can be electro-magnetically released are feasible. From a cost perspective, the simplest solution is the use of a disk or drum brake. The shear device or the shear disk is, in this case, extended in radial direction and includes--along this direction--a working surface for the brake disks. Preferably, the extension in radial direction is chosen to be as large as possible in order to provide the largest possible working surfaces for the brake disks which, in turn, reduces the braking pressures of the disks.
If a ratchet mechanism is used to slow down the shear device or shear disk, the ring has a gear tooth pattern found on the side facing away from the shear valves (in radial direction) as well as on a surface in radial direction. This gear tooth pattern forms the notches for the engagement of a ratchet or a locking pin. The locking pin or ratchet is, in normal operation, held in a fixed position in relation to the machine frame. When the maximum allowable torque is exceeded, a magnet attached to one of the universal drivetrains is activated in order to unlock the ratchet or locking pin and, subsequently, to move the ratchet or locking pin into the notches for engagement.
For the response time, that is, the period of time between the sensing of the unacceptably high torque and the sheering off of the sheer valves, the number of notches or the speed of the movement of the ratchet or locking bolt into the notches is the key factor. Through appropriate design measures, this response time can be optimized. For sensing the torque, or for determining a value proportional to the torque on the universal drivetrain or on the rolls, or for determining the disturbance value, different systems of sensing or capturing these values can be used. The torque sensing and/or the determination of the value proportional to the torque and/or the disturbance value can be accomplished mechanically, electronically, or optically. Mechanical sensing/acquisition devices are based on the strain gage principle or on a mechanical torque measurement device. It is also feasible to use combinations of the various methods for sensing torque.
The coupling of the device, used to measure the torque and/or the value proportional to the torque and/or the disturbance value, to the relief mechanism is best accomplished electronically. Mechanical coupling is feasible; however, it requires precise manufacturing tolerances since the distance between the sensing location and the sheering device is usually very large. The connection between the sensing/acquisition device and the relief mechanism can be accomplished, for example, by use of an electronic control device whose inputs include "torque exceeded" and whose outputs include a signal to slow down the sheer device or to ignite the explosive substance.
Through the placement of the safety coupling ahead of the transfer gearbox, one single safety coupling is sufficient in such a drivetrain to protect against a torque overload condition. The coupling body, whose purpose is to establish a frictional engagement between two machine components, is positioned, corresponding to the torque to be transmitted, ahead of the transfer gearbox. The shear device is activated externally, i.e., not directly through deformation in the drivetrain when exceeding the maximum allowable torque and/or the value proportional to the torque. Thereby, a very cost-effective solution to prevent a torque overload condition in a drivetrain can be realized. The design of such a relief mechanism is done in a manner to achieve the shortest possible response times, i.e. the shortest possible time span between the occurrence of torque spikes and the interruption of the torque flow ahead of the transfer gearbox. The spacing between the drivetrains no longer limits the torque capacity of the safety coupling.
Preferably, the oblong openings of the shear device, especially the shear disks, which encompass the shear valves, are made to different widths. This means that during braking or stopping of the shear disk, the shearing events of the individual shear valves occur sequentially. This has the unique advantage that the shearing forces required to shear off the shear valves are relatively low. The shearing of the shearing valve occurs in a sequential manner, i.e., the shearing of one valve is followed by the shearing of the next valve, which contributes to a substantial improvement in the running smoothness of the drive system. If all valves are sheared off at the same time, relatively high forces are required, which leads to undesirable, high vibration levels in the drive system. The number of shear valves provided on a coupling body and the number of oblong openings in the shear device should be the same. It is, however, feasible to design a shear disk with a certain number of oblong openings in such a way so that it can be adapted to different coupling bodies, resulting in the opportunity to take advantage of the concept of modular construction.
Preferably, all coupling elements, that is, all elements that serve to disrupt the flow of the torque, are made with small masses in order to quickly overcome the inertia of the masses during activation of the relief mechanism.
An embodiment of a safety coupling includes a machine element (i.e, a separator bolt) containing the explosive substance serving to activate the shear device by ignition of the substance. In doing so, conventional shear devices are applied--a shear disk for example, which is placed in a fixed position relative to the coupling body and, when triggered, the ring can be moved in axial or radial direction relative to the coupling body. An additional device to accelerate this relative motion is feasible by the use of pre-loaded springs, for example. There should be at least two separator bolts mounted equally-spaced around the circumference of the driveshaft. The shear device itself can be mounted in a torsionally rigid manner onto the driveshaft, although it should be designed to be moveable in axial direction. One possibility of such an arrangement includes the use of a splined shaft connection between the driveshaft and the shear device. The shear device can also be mounted in a freely rotating manner on the driveshaft. A torsionally rigid connection is not necessarily required, although it appears to be a good solution when applied in combination with a shear disk, since the disk with the respective oblong openings can be designed to accommodate the sealing valves, which are frequently designed in the form of valves.
The separator bolt is coupled with an ignition device, which is activated in response to a signal from the sensing/acquisition device. The sensing/acquisition device should be a control device including at least one input for actual values and one output. The two inputs are each connected to a sensing/acquisition device which determines the current torque value and/or the value which is directly or indirectly proportional to the torque, and/or a disturbance value. The actual value is compared with either a fixed or a calibratable maximum allowable value stored in the control device. If a deviation occurs, a signal is issued at the output of the control device, initiating the triggering of the relief mechanism, or in this case, the ignition of the separator bolt. Since the data transfer, the data comparison, and the triggering of the relief mechanism occurs at the speed of light, such a safety coupling is especially useful for rapid triggering during a torque overload condition or during any other disturbances. The relief mechanism can be triggered immediately upon recognition of a torque spike or even prior to that event. Mechanical sensing/acquisition devices always have some delays in this regard.
A further possibility is to locate the shear device by use of pre-loaded springs or separator bolts (which also need to be ignited) and upon a triggering event, (i.e., the result of an overload condition) an acceleration of the shear device toward the sealing valves takes place. The shear device can be designed so that it interacts with the sealing valves in radial as well as axial direction. The addition of the pre-tension accelerates the relief action.
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, sectional side view of a safety coupling in a drive system as applied to a roll mill;
FIG. 2a is a partial, schematic, sectional side view of the relief mechanism of FIG. 1, shown with a disk brake acting upon a shear disk;
FIG. 2b is a top view of the relief mechanism of FIG. 2a;
FIG. 3a is a schematic, fragmentary, sectional view of a ratchet mechanism of the present invention;
FIG. 3b is a schematic, sectional view of the ratchet mechanism of FIG. 3a;
FIG. 4 is a fragmentary, front view of the shear disk of FIG. 2b along line I--I.
FIG. 5 is a schematic, side, sectional view of another embodiment of a relief mechanism, according to this invention, with an element such as a separator bolt, containing the explosive substance; and
FIG. 6 is a partial, schematic, sectional side view of yet another embodiment of a relief mechanism, according to this invention, with a pre-loaded shear device.
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
Referring now to the drawings and particularly to FIG. 1, there is shown a design of a drive system frequently used in a roll mill application, with at least two universal drivetrains and an integrated device to protect against a torque overload condition. A working roll 1 and a working roll 2 are each driven by a respective universal drivetrain 3 and 4. The power generated by the power source 5 (i.e., an electric motor) is transferred to the universal drivetrains 3 and 4 by use of appropriate speed/torque converters. The connection of motor 5 to the gear reduction unit 6 is accomplished by use of a torsionally rigid coupling 7, which can be designed as a denture clutch. Downstream of the gear reduction unit 6 is a transfer gearbox 8. Transfer gearbox 8 serves to distribute the power to the individual universal drivetrains 3 and 4. Between the gear reduction unit 6 and the transfer gearbox 8, resides the safety coupling 9. Safety coupling 9 serves to--in addition to transmitting torque from the gear reduction unit 6 to the transfer gearbox 8--to protect against a torque overload condition. Safety coupling 9 includes a coupling body 24 and a relief device 31. Coupling body 24 includes at a least thin-walled sleeve 12, forming a wall 13 of a ring-shaped chamber 14 extending in axial direction. Ring-shaped chamber 14 can be pressurized with a medium in order to elastically deform the sleeve 12 in radial direction. The realization of the non-positive connection between the gear reduction unit 6 and the transfer gearbox 8 by use of safety coupling 9 can be accomplished in several ways. For example, flange 15 can be connected to output shaft 10 of gear reduction unit 6 in a torsionally rigid manner. Flange 15 is connected to input shaft 11 of transfer gearbox 8 by use of coupling body 24 in a non-positive manner. Coupling body 24 of safety coupling 9 divides the drivetrain into two parts--a first part I, which is connected to the power source or motor 5, and a second part, which is connected to the power take-off--in this case the working rolls 1 and 2. Transfer gearbox 8 is, in the presented exemplification, designed to include a set of spur gears. These include spur gears 16 and 17. Spur gear 16 is mounted torsionally rigid onto transmission input shaft 11 of transfer gearbox 8. Transmission input shaft 11 is the same shaft as the output shaft 19 of the transfer gearbox 8. Spur gear 17 is mounted torsionally rigid onto a second transmission output shaft 20 of the transfer gearbox 8. Output shafts 19 and 20 of the transfer gearbox 8 are connected torsionally rigid to universal drivetrains 3 and 4.
The relief mechanism 31 can be designed in different ways, as exemplified in FIGS. 2 and 3. Relief mechanism 31 serves to provide a pressure relief in the ring-shaped chamber 14. The activation of the relief mechanism 31 occurs through coupling 45 with the sensing/acquisition devices, in this case the torque sensing/acquisition device 46 and 47 which are assigned to the universal drivetrains 3 and 4. Coupling 45 can be a control device. The torque sensing/acquisition devices 46 and 47 can be of various types. To acquire the torque, mechanically-based torque sensing/acquisition devices can be utilized. These can be designed as published in the brochures by the corporation, "Ringspan". These work on the basic principle that a small torsional deformation is converted into an axial movement by use of a lever system. This axial motion is then converted into a voltage signal proportional to the torque by use of an inductive difference generator. These torque-proportional voltage signals can subsequently function as input signals to a control/regulator unit, which processes these signals into an output signal for the activation of the shear device.
The safety coupling, designed to protect against a torque overload condition, is placed--in the case of a roll mill--between transfer gearbox 8 and gear reduction unit 6. This assures that safety coupling 9 is positioned as closely as possible to the origin of possible disturbances. It is also possible, although not shown here in detail, to integrate the gear reduction unit 6 and the transfer gear box 8 into one unit. Denture clutch 7 would, in this case, no longer be necessary and would be replaced by safety coupling 9. In such a case, the torque flow is disrupted directly between the power source, in this case, motor 5, and the transfer gearbox 8.
FIGS. 2a and 2b depict, in accordance to this invention, a cross-sectional view of relief mechanism (ref. FIG. 1) for a safety coupling using disk brakes to slow down the shear disk. The labeling used in this illustration is the same as used in the previous illustration. Safety coupling 9a connects the fist part I of drive system with the second part II, through the jamming of flange 15 of the first part of the drive system against bushing 26 and bushing 27, as well as against the transmission input shaft 11 of the transfer gearbox 8 of the second part II of the drive system.
To this end, the ring-shaped chamber 14 is pressurized with a medium. The ring-shaped chamber 14 utilizes supply drillings 28, which reside on the outside 29 of the coupling body 24 and extend in the radial direction to the ring-shaped chamber 14. The supply drillings 28 are sealed by sealing valves, also referred to as shear valves 50. Shear valves 50 protrude only minimally above the outer periphery 29 of coupling body 24. Coupling body 24 is mounted rotatable on bushing 27, which, in turn, is connected torsionally rigid to transmission shaft 11 of transfer gearbox 8. Also mounted on bushing 27 is the shear disk 30 of relief mechanism 31.
Shear disk 30 includes a radial extension in form of a ring 32. Disk brake device 33 is also mounted in a freely rotating manner relative to shear disk 30. All elements of the safety coupling 9a are tied to the axis A, which means that none of these parts are mounted externally on the framework, preventing the transfer of vibration onto the framework. Disk brake device 33 includes a central housing 34 with two disks 35 and 36, which can be pressed against surfaces 37 and 38 of ring 32. The activation of the disk brake device can be electronically controlled. Shear disk 30 comprises oblong openings 39, which partially encompass shear valves 50, as shown in FIG. 2b, view x, as referenced in FIG. 2a. The oblong openings 39 should be open to the side.
When the disk brake device 33 is activated, disks 35 and 36 are pressed against surfaces 37 and 38 of ring 32 and the rotational speed of the shear disk 30 reduces until it comes to a standstill. This creates a relative motion between the oblong openings 39 and the shear valves 50, causing valves 50 to be sheared off. This, in turn, opens the supply drillings 28, relieving the pressure inside chamber 14. The non-positive connection between the first and second part of the drive train is suspended and the torque flow is interrupted.
FIGS. 3a and 3b illustrate a device designed to slow down or stop the shear disk 30 in accordance to FIG. 1. The same components are labeled using the same reference numbers as used in the previous Figures. Shear disk 30 includes, in this embodiment also, oblong openings 39 that are open to the side, which partially encompass shear valves 50. Shear disk 30 is, in this version also, extended in radial direction. Shear disk 30 includes on the circumference 40 notches 41, positioned in radial or axial direction. Notches 41 can be designed in form of a sawtooth pattern. Engaged with notches 41 is at least one locking element, which can be in the form of a ratchet 43 or a locking bolt 44. Both possibilities are shown in FIG. 3a. The activation of locking bolt 44 occurs perpendicular to axis A of the transmission input shaft 11. When using ratchet 43 to slow down or lock shear disk 30, the locking action occurs by pivoting the ratchet 43 around a fixed pivot point P1. For this purpose, ratchet 43 is positioned radially off to the side as far as possible. Ratchet 43 is held in its position by use of pre-loaded springs 46. The activation of the ratchet 43, that is, the pivoting around P1, is accomplished by magnet 47. Correspondingly, the activation of locking bolt 44 can also be accomplished by magnet 47.
FIG. 4 illustrates a preferred embodiment of a shear disk, which can, for example, be applied to the relief mechanisms 31, which are depicted in FIGS. 2 and 3. The shear disk and coupling body are shown here in view I--I (ref. 2b). The coupling body 24 includes a plurality of supply drillings 28 (shown here by dash-point-dash lines), leading to the ring-shaped chamber 14. These drillings 28 are sealed by shear valves 50, or in this case, valves 50a, 50b, 50c. Shear disk 30a, which encompasses part of coupling body 24, includes oblong openings 39, which should be open to the side. The oblong openings 39, in this case, 39a through 39c, are made to different sizes, so that the distances S 1 through S 3 between the edges of the oblong openings 39 and the interface surfaces of the shear valves 50a through 50c--in direction of rotation--become increasingly larger. This has the result that valves 50 are sheared off in a sequential manner at relatively low force requirements.
FIG. 5 illustrates, in accordance with the intent of this invention, a relief mechanism 31 for a safety coupling 9 using a shear disk 30 which is activated by use of a separator bolt (also shown in FIG. 1). The labeling used in this illustration is the same as used in the previous illustration. Safety coupling 9 connects the first part I of the drive system to the second part II, through the jamming of flange 15 of the first part I of the drive system against bushing 26, as well as against the transmission input shaft 11 of the transfer gearbox 8 of the second part II of the drive system.
To this end, the ring-shaped chamber 14 is pressurized with a medium. The ring-shaped chamber 14 utilizes supply drillings 28, which reside on the outside 29 of the coupling body 24 and extend in the radial direction to the ring-shaped chamber 14. The supply drillings 28 are sealed by sealing valves, also referred to as shear valves 50. Shear valves 50 protrude only minimally above the outer periphery 29 of coupling body 24. Mounted on bushing 26 is an element 27 carrying shear disk 30 of relief mechanism 31. The shear disk 30 is connected to element 27 in a torsionally rigid fashion, for example, by use of a splined shaft connection 55. Shear disk 30 is moveable in relation to bushing 27 in axial direction, parallel to the centerline of the drive shaft. Acting on shear disk 30 is at least one separator bolt in form of an explosive bolt 51. If several explosive bolts 51 are used, then these should be placed on the shear disk 30 on the same diameter and equally-spaced. The explosive bolts 51 are connected to an ignition device, which is linked to the output of a control device--not shown here--although it could be the same control device 45, as shown in FIG. 1. In response to the input signal, an output signal is initiated to trigger the ignition process, corresponding to the torque and disturbance values, which have been established.
FIG. 6 illustrates an additional embodiment that includes a shear disk 30 that is pre-loaded by spring 53. During normal operation, the shear disk is located in its position relative to the sealing valves 50 by use of separator bolts 51. In the event of an overload condition, the separator bolts 51 are fired, and the shear disk is accelerated in axial direction to shear off the valve heads of the sealing valves 50 of the safety coupling 9. "Dynamit Nobel" (a corporation) publishes the separator bolts 51 and the elements holding the explosive substances in various forms in brochures.
In terms of the placement of the separator bolts 51 in relation to the shear device, (preferable a shear disk 30) there are many other design alternatives. However, they all have one thing in common: upon recognition of a torque spike, a firing of the explosive substance occurs, generating an immediate force acting on the valve, which, in turn, causes the sealing valves to vent, triggering an interruption of the torque transmission by hydraulically jamming sleeves and bushings. More design variations are accorded to the expert's discretion, which is why these additional design variations are not further elaborated here.
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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A drive system for the transmission of power from a drive source to a plurality of output trains includes a transfer gear connected upstream of the output trains, and an arrangement for ensuring that the output trains are not overloaded with torque. The arrangement includes a safety clutch with a basic clutch body for the frictionally engaged connection of two machine parts, and at least one thin-walled sleeve which forms a wall of an annular chamber upon which pressure medium can act. The arrangement further includes at least one feed line which extends through the clutch body to the annular chamber and can be closed off in an air and fluid-tight manner by use of closure elements. The arrangement finally includes a pressure-relief mechanism. The safety clutch is arranged upstream of the transfer gear. The pressure-relief mechanism is coupled to an arrangement for detecting the torque at the output trains and/or a magnitude which is proportional to the torque and is associated with each output train, and/or an influencing quantity in the area surrounding the machine. The clutch includes a device for activating the pressure-relief mechanism when the torque and/or a magnitude proportional to the torque and/or an influencing quantity is/are exceeded.
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FIELD
[0001] The present disclosure relates to suture loop constructions and, more particularly, to a locking suture loop construction and a method of its construction.
BACKGROUND
[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
[0003] It is commonplace in arthroscopic procedures to employ sutures and anchors to secure soft tissues to bone. Despite their widespread use, several improvements in the use of sutures and suture anchors can be made. For example, the procedure of tying knots can be very time consuming, thereby increasing the cost of the procedure and limiting the capacity of the surgeon. Furthermore, the strength of the repair may be limited by the strength of the knot. This latter drawback may be of particular significance if the knot is tied improperly as the strength of the knot in such situations can be significantly lower than the tensile strength of the suture material.
[0004] To overcome this problem, sutures having a single preformed loop have been provided. FIG. 1 represents a prior art suture construction. As shown, one end of the suture is passed through a passage defined in the suture itself. The application of tension to the ends of the suture pulls a portion of the suture through the passage, causing a loop formed in the suture to close. Unfortunately, relaxation of the system can allow a portion of the suture to translate back through the passage, thus relieving the desired tension.
[0005] It is an object of the present teachings to provide an alternative device for anchoring sutures to bone and soft tissue. The device, which is relatively simple in design and structure, is highly effective for its intended purpose.
SUMMARY
[0006] To overcome the aforementioned deficiencies, a method for configuring a braided tubular suture and a suture configuration are disclosed. The method includes passing a first end of the suture through a first aperture into a passage defined by the suture and out a second aperture defined by the suture so as to place the first end outside of the passage. A second end of the suture is passed through the second aperture into the passage and out the first aperture so as to place the second end outside of the passage.
[0007] In another embodiment, a method for configuring a braided suture is disclosed. The method includes passing a first end of the suture through the first aperture defined between the pair of fibers defining the suture and into a longitudinal passage defined by the suture. The first end of the suture is then passed through a second aperture defined between a second pair of fibers so as to place the first end outside of the longitudinal passage. A second end of the suture is passed through a third aperture defined between a third pair of fibers and into the longitudinal passage. The second end is passed through an aperture defined by a fourth pair of fibers so as to place the second end outside of the longitudinal passage.
[0008] In another embodiment, a suture construction is provided having a suture with first and second ends and an enlarged central portion defining an interior longitudinal passage. First and second passage depending apertures are disposed between the first and second ends. The first end being placed through the first and second apertures so as to place a first portion of the suture within the longitudinal passage. The second end being placed through the second and first aperture so as to place a second portion of the suture within the longitudinal passage.
[0009] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
DRAWINGS
[0010] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
[0011] FIG. 1 represents a prior art suture configuration;
[0012] FIGS. 2A and 2B represent suture constructions according to the teachings;
[0013] FIG. 3 represents the formation of the suture configuration shown in FIG. 2A ;
[0014] FIGS. 4A and 4B represent alternate suture configurations;
[0015] FIGS. 5-7 represent further alternate suture configurations;
[0016] FIG. 8 represents the suture construction according to FIG. 5 coupled to a bone engaging fastener;
[0017] FIGS. 9-11 represent the coupling of the suture construction according to FIG. 5 to a bone screw;
[0018] FIGS. 12A-12E represent the coupling of a soft tissue to an ACL replacement in a femoral/humeral reconstruction; and
[0019] FIGS. 13A-13D represent a close-up view of the suture shown in FIGS. 1-11C .
DETAILED DESCRIPTION
[0020] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.
[0021] FIG. 2A represents a suture construction 20 according to the present teachings. Shown is a suture 22 having a first end 24 and a second end 26 . The suture 22 is formed of a braided body 28 that defines a longitudinally formed hollow passage 30 therein. First and second apertures 32 and 34 are defined in the braided body 28 at first and second locations of the longitudinally formed passage 30 .
[0022] Briefly referring to FIG. 3 , a first end 24 of the suture 22 is passed through the first aperture 32 and through longitudinal passage 30 formed by a passage portion, and out the second aperture 34 . The second end 26 is passed through the second aperture 34 , through the passage 30 and out the first aperture 32 . This forms two loops 46 and 46 ′. As seen in FIG. 2B , the relationship of the first and second apertures 32 and 34 with respect to the first and second ends 24 and 26 can be modified so as to allow a bow-tie suture construction 36 . As described below, the longitudinal and parallel placement of first and second suture portions 38 and 40 of the suture 22 within the longitudinal passage 30 resists the reverse relative movement of the first and second portions 38 and 40 of the suture once it is tightened.
[0023] The first and second apertures are formed during the braiding process as loose portions between pairs of fibers defining the suture. As further described below, the first and second ends 24 and 26 can be passed through the longitudinal passage 30 multiple times. It is envisioned that either a single or multiple apertures can be formed at the ends of the longitudinally formed passage.
[0024] As best seen in FIGS. 4A and 4B , a portion of the braided body 28 of the suture defining the longitudinal passage 30 can be braided so as to have a diameter larger than the diameter of the first and second ends 24 and 26 . Additionally shown are first through fourth apertures 32 , 34 , 42 , and 44 . These apertures can be formed in the braiding process or can be formed during the construction process. In this regard, the apertures 32 , 34 , 42 , and 44 are defined between adjacent fibers in the braided body 28 . As shown in FIG. 4B , and described below, it is envisioned the sutures can be passed through other biomedically compatible structures.
[0025] FIGS. 5-7 represent alternate constructions wherein a plurality of loops 46 a - d are formed by passing the first and second ends 24 and 26 through the longitudinal passage 30 multiple times. The first and second ends 24 and 26 can be passed through multiple or single apertures defined at the ends of the longitudinal passage 30 . The tensioning of the ends 24 and 26 cause relative translation of the sides of the suture with respect to each other.
[0026] Upon applying tension to the first and second ends 24 and 26 of the suture 22 , the size of the loops 46 a - d is reduced to a desired size or load. At this point, additional tension causes the body of the suture defining the longitudinal passage 30 to constrict about the parallel portions of the suture within the longitudinal passage 30 . This constriction reduces the diameter of the longitudinal passage 30 , thus forming a mechanical interface between the exterior surfaces of the first and second parallel portions as well as the interior surface of the longitudinal passage 30 .
[0027] As seen in FIGS. 8-11 , the suture construction can be coupled to various biocompatible hardware. In this regard, the suture construction 20 can be coupled to an aperture 52 of the bone engaging fastener 54 . Additionally, it is envisioned that soft tissue or bone engaging members 56 can be fastened to one or two loops 46 . After fixing the bone engaging fastener 54 , the members 56 can be used to repair, for instance, a meniscal tear. The first and second ends 24 , 26 are then pulled, setting the tension on the loops 46 , thus pulling the meniscus into place. Additionally, upon application of tension, the longitudinal passage 30 is constricted, thus preventing the relaxation of the tension caused by relative movement of the first and second parallel portions 38 , 40 , within the longitudinal passage 30 .
[0028] As seen in FIGS. 9-11B , the loops 46 can be used to fasten the suture construction 20 to multiple types of prosthetic devices. As described further below, the suture 22 can further be used to repair and couple soft tissues in an anatomically desired position. Further, retraction of the first and second ends allows a physician to adjust the tension on the loops between the prosthetic devices.
[0029] FIG. 11 b represents the coupling of the suture construction according to FIG. 2B with a bone fastening member. Coupled to a pair of loops 46 and 46 ′ are tissue fastening members 56 . The application of tension to either the first or second end 24 or 26 will tighten the loops 46 or 46 ′ separately.
[0030] FIGS. 12A-12E represent potential uses of the suture constructions 20 in FIGS. 2A-7 in an ACL repair. As can be seen in FIG. 12A , the longitudinal passage portion 30 of suture construction 20 can be first coupled to a fixation member 60 . The member 60 can have a first profile which allows insertion of the member 60 through the tunnel and a second profile which allows engagement with a positive locking surface upon rotation. The longitudinal passage portion 30 of the suture construction 20 , member 60 , loops 46 and ends 24 , 26 can then be passed through a femoral and tibial tunnel 62 . The fixation member 60 is positioned or coupled to the femur. At this point, a natural or artificial ACL 64 can be passed through a loop or loops 46 formed in the suture construction 20 . Tensioning of the first and second ends 24 and 26 applies tension to the loops 46 , thus pulling the ACL 64 into the tunnel. In this regard, the first and second ends are pulled through the femoral and tibial tunnel, thus constricting the loops 46 about the ACL 64 (see FIG. 12B ).
[0031] As shown, the suture construction 20 allows for the application of force along an axis 61 defining the femoral tunnel. Specifically, the orientation of the suture construction 20 and, more specifically, the orientation of the longitudinal passage portion 30 , the loops 46 , and ends 24 , 26 allow for tension to be applied to the construction 20 without applying non-seating forces to the fixation member 60 . As an example, should the loops 24 , 26 be positioned at the member 60 , application of forces to the ends 24 , 26 may reduce the seating force applied by the member 60 onto the bone.
[0032] As best seen in FIG. 12C , the body portion 28 and parallel portions 38 , 40 of the suture construction 20 remain disposed within to the fixation member 60 . Further tension of the first ends draws the ACL 64 up through the tibial component into the femoral component. In this way, suture ends can be used to apply appropriate tension onto the ACL 64 component. The ACL 64 is then fixed to the tibial component using a plug or screw as is known.
[0033] After feeding the ACL 64 through the loops 46 , tensioning of the ends allows engagement of the ACL with bearing surfaces defined on the loops. The tensioning pulls the ACL 64 through a femoral and tibial tunnel. The ACL 64 could be further coupled to the femur using a transverse pin or plug. As shown in FIG. 12E , once the ACL is fastened to the tibia, further tensioning can be applied to the first and second ends 24 , 26 placing a desired predetermined load on the ACL. This tension can be measured using a force gauge. This load is maintained by the suture configuration. It is equally envisioned that the fixation member 60 can be placed on the tibial component 66 and the ACL pulled into the tunnel through the femur. Further, it is envisioned that bone cement or biological materials may be inserted into the tunnel 62 .
[0034] FIGS. 13A-13D represent a close-up of a portion of the suture 20 . As can be seen, the portion of the suture defining the longitudinal passage 30 has a diameter d 1 which is larger than the diameter d 2 of the ends 24 and 26 . The first aperture 32 is formed between a pair of fiber members. As can be seen, the apertures 32 , 34 can be formed between two adjacent fiber pairs 68 , 70 . Further, various shapes can be braided onto a surface of the longitudinal passage 30 .
[0035] The sutures are typically braided of from 8 to 16 fibers. These fibers are made of nylon or other biocompatible material. It is envisioned that the suture 22 can be formed of multiple type of biocompatible fibers having multiple coefficients of friction or size. Further, the braiding can be accomplished so that different portions of the exterior surface of the suture can have different coefficients of friction or mechanical properties. The placement of a carrier fiber having a particular surface property can be modified along the length of the suture so as to place it at varying locations within the braided constructions.
[0036] The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.
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A suture construction and method for forming a suture construction is disclosed. The construction utilizes a suture having an enlarged central body portion defining a longitudinal passage. First and second ends of the suture are passed through first and second apertures associated with the longitudinal passage to form a pair of loops. Portions of the suture lay parallel to each other within the suture. Application of tension onto the suture construction causes constriction of the longitudinal passage, thus preventing relative motions of the captured portions of the suture.
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CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority under 35 U.S.C. §119 to European Patent Application EP06291145.8, filed Jul. 11, 2006, titled “A method and a system for protecting path and data of a mobile agent within a network system,” which is incorporated herein by reference in its entirety.
TECHNICAL FIELD
This description refers to the field of mobile agent technology, particularly to mobile agent security in network systems.
BACKGROUND
In computer science, a mobile agent is a composition of computer software and data which is able to migrate from one server to another autonomously and continue its execution on a destination server. A mobile agent inherits some of the characteristics of an agent. An agent is a computational entity which acts on behalf of other entities in an autonomous fashion, performs its actions with some level of proactivity and/or reactiveness and exhibits some level of key attributes of learning, cooperation and mobility. A mobile agent, namely, is a type of a software agent, with the feature of autonomy, social ability, learning, and most important, mobility. When the term mobile agent is used, it refers generally to a process that can transport its state from one environment to another, with its data intact, and still be able to perform appropriately in the new environment. The mobile agent environment is, generally speaking, a software system that is distributed over a network system of heterogeneous servers. Its primary task is to provide an environment in which mobile agents can execute. The mobile agent environment is built on top of a host system. Mobile agents travel between mobile agent environments. They can communicate with each other either locally or remotely. Finally, communication can also take place between a mobile agent and a host service. Mobile agents are active in that they may choose to migrate between servers at any time during the execution. This makes them a powerful tool for implementing distributed applications in a network system. During their route through the network system mobile agents can carry data with them. These data can be data that is necessary for their execution on a certain server and results from calculations that have been performed on a certain server. The route of a mobile agent can be defined in advance, or the mobile agent can adapt its route on its way based on certain events. After the completion of their tasks most mobile agents return to their departure point to return the results they gathered.
There are quite a lot of advantages of using mobile agents which are described in the following. Mobile agents reduce network traffic. Some applications first download a large amount of data from a server and then process this data to a smaller amount, e.g. search and filter applications like for example data-mining. If one would use mobile agents for these programs, then these mobile agents would be able to execute the work on the server itself, without congesting the network system because only the results of the calculation will be sent back.
Furthermore, by means of mobile agents, an asynchronous and autonomous execution on multiple heterogeneous network servers is possible. Some applications need a large amount of client-server interactions which can be done through classic client-server method invocations or with web services used in a so-called Enterprise Services Architecture (ESA). Also in this case mobile agents can be more efficient. A mobile agent can work asynchronously and autonomously while the system that sent the mobile agent is no longer connected to the network system. Mobile servers like laptops and PDAs, that mostly have an uncertain and expensive connection with relative low bandwidth, can therefore make proper use of mobile agents.
Moreover, mobile agents have the possibility to adapt themselves to changes in their execution environment. This is why mobile agents can be used for example in load-balancing. When a server is starting to become overloaded, some processes can be placed to another server within the network system in the form of a mobile agent, where they can continue the execution. Also other application scenarios exist where intelligent agents can make efficient decisions based on the changing execution environment. An e-business scenario with mobile agents would allow, for example, to find the cheapest price for an airplane ticket, car rental and hotel booking. Most airlines have deals with car rental companies and hotels. This information is available when the mobile agent will visit the server of the airline company. The mobile agent will collect the prices of the airplane ticket and then continues its route to the service of cooperating car rental companies and hotels.
As already mentioned, the use of mobile agents is tolerant of network faults. Mobile agents are able to operate without an active connection between a client and a server.
Common applications of mobile agents include for example resource availability, discovery, monitoring, information retrieval, network management and dynamic software deployment.
If one wants to execute a mobile agent on a server, then this mobile agent comes under the complete control of the server. If a server has malicious intentions and wants to change the mobile agent or simply delete the mobile agent, this is impossible to prevent. However, it should be tried to make targeted, malicious changes impossible by applying detection mechanisms. With cryptographic techniques one can try to make sure that a server cannot read information that is not targeted towards it. The fact that the mobile agent travels from one server to another causes, however, that classic methods are not sufficient anymore to protect these mobile agents.
There are some existing methods to protect mobile agents against servers. Generally, there are two categories of existing methods to protect mobile agents against servers, namely so-called Blackbox methods and Partial Protection methods.
The goal of Blackbox methods is to hide the whole program code of a mobile agent for a server, so that the intention of the mobile agent is not clear and the server will not be able to make targeted modifications. There are basically three different approaches in this category.
A first approach can be called “Tamper-free Hardware”. One uses here a special manufactured tool as execution environment for the mobile agents. The internal specifications of the system are physically separated from the outside world and impossible to maintain without damaging the tool, which can be easily verified. This approach gives a very good protection. However, it is practically unacceptable on a large scale because of the high manufacturing costs. For more information reference is made to “U. G. Wilhelm, S. Staamann, L. Buttyan. Introducing Trusted Third Parties to the Mobile Agent Paradigm. In J. Vitek and C. Jensen, Secure Internet Programming: Security Issues for Mobile and Distributed Objects, volume 1603, pages 471-491. Springer-Verlag, New York, N.Y., USA, 1999” and “Bennet Yee. Using Secure Coprocessors. PhD Thesis, May 1994”.
A further approach can be called “Obfuscated Code”. This approach tries to rearrange the code of the mobile agent in such a way that it becomes incomprehensible, but still has the same effect. The technique is closely related to obfuscation techniques to prevent reverse engineering. At this moment there is no method that makes the code incomprehensible infinitely in time. If one has enough processing capacity, one can rediscover the signification of the code. A less strict variant of this approach is the time limited protection, i.e. the obfuscated code is only valid for a certain period in time, and after that the mobile agent becomes invalid. A large problem here is that one has not yet defined ways to calculate the effectiveness of the obfuscation algorithms. In other words, it is not possible to calculate an underlimit for the time. More information can be found in “Fritz Hohl. Time Limited Blackbox Security: Protecting Mobile Agents from Malicious Hosts. In Giovanni Vigna, Mobile Agent Security, pages 92-113. Springer-Verlag. 1998”.
A further approach refers to Mobile Cryptography. Suppose one has an algorithm to calculate a function f and one wants to know from a certain input value x the function value f(x) on a server without the server knowing f. This would be possible if one could encrypt f in a way that E[f(x)], the function value of x calculated with the encrypted function, could be decrypted back to f(x). This technique is very promising, but the biggest challenge remains to develop encryption schemas E for arbitrary functions f. For now E exists only for certain classes of polynomials and rational functions as it is described in reference “T. Sander and C. Tschudin. Towards Mobile Cryptography. In Proceedings of the IEEE Symposium on Security and Privacy, Oakland, Calif., 1998”.
Instead of covering the whole mobile agent for the servers in the approach of partial protection, part of the mobile agent will be protected, like confidential information that the mobile agent carries with him. In this case, however, the servers can perform targeted attacks against the mobile agents, which was not possible with blackbox methods. The mobile agents are vulnerable to so-called cut-and-paste attacks. One can remove data from a mobile agent and use another mobile agent to get to know the confidential information.
The purpose of an existing method described in the following and further described in reference “Neeran M. Karnik and Anand R. Tripathi. Security in the Ajanta mobile agent system. Software, Practice and Experience, 31(4): 301-329, 2001”, is to make data that the mobile agent carries with him only accessible to certain servers. It is assumed in the following that the servers within the network system are all provided with a pair of a public key and a private key, respectively. One could try to make data that a mobile agent carries with it only accessible to certain servers by encrypting those data with the respective public keys of the servers. To check the integrity and the authenticity of the data one can then also calculate a digital signature on the whole. This can be described by the following mathematical term:
[{m 1 }KS 1 , . . . , {m n }KS n ]PKS 0 (1)
wherein m i is a message for a server S i , KS i is the public key of server S i and PKS 0 is the private key of the owner of the respective mobile agent, namely the server S 0 .
When a mobile agent arrives on a certain server, this server verifies first the signature on the whole data structure with the public key of the agent owner. After this operation, the server checks if the mobile agent carries messages that are destinated for that server. If this is the case, the respective server can decrypt these messages with its private key and make them available to the mobile agent, if appropriate.
This described method makes use of classic cryptographic techniques to protect the data of the mobile agent. However, because the mobile agents migrate from one server to another before returning to their home server, the mobile agents need additional protection. This will become clear from the description of the following attack.
To clarify the attack described in the following, the assumption is made that the mobile agent only carries one message. The server owning the mobile agent as well as each server within the network system is associated with a pair of a public key and a private key, respectively. Suppose that a server A wants to send a secret message to a server B via a network system. Server A encrypts this secret message with the public key of server B. Then server A sends a mobile agent on its way through the network system to the respective server B. For simplicity it is assumed in the following that the mobile agent only consists of its program code PA and its container containing the message. It is assumed further that the mobile agent first arrives on a server of user E on its way to server B. This scenario can be described as follows:
A=>E:PA,[{mB}KB]PKA (2)
wherein PA is the program code of the mobile agent, mB is the secret message for server B, KB is the public key of server B and PKA is the private key of server A as the owner of the mobile agent.
Server E can in this situation just remove the private key as the signature of server A, put the encrypted message mB in its own agent and sign the whole data container with its own private key PKE. Then server E can send the mobile agent to server B which can be described as follows:
E=>B:PE,[{mB}KB]PKE,
B:PE,[{mB}KB]PKE=>{{mB}KB}PKB=mB (3)
wherein PE describes the program code of the mobile agent owned by server E and PKE describes the signature, namely the private key of server E as the owner of the new mobile agent.
Server B decrypts unaware of server E's intents the message mB and makes it available to the actual mobile agent. If server E programs its mobile agent's code PE in a way that it keeps track of the message mB, then server E has full access to this secret message mB when the mobile agent returns back to server E which can be described as follows:
B=>E:PE,[{mB}KB]PKE,mB (4)
The purpose of another existing method described in the following and further described in reference “Green, S., Somers, F., Hurst, L., Evans, R., Nangle, B., Cunningham, P.; Software agent: A review, May (1997)” is to add data that an agent finds on a server to a secure data container. It is assumed in the following, as already mentioned, that the servers within the network system are all provided with a pair of a public key and a private key, respectively. Also the server from which the mobile agent is sent out, in the following called the first server, has a public key and a private key. Before sending a mobile agent on its route through the network system a nonce N o is first encrypted with the public key of the first server, namely the server from which the mobile agent will be sent out. Within the scope of the present specification the term first server, agent owner and the server from which the mobile agent is sent out are used synonymously. The encrypted nonce N o is kept secret and thus only known by the first server and can be written as follows:
C o ={N o }KS 0 (5)
wherein N o is the mentioned nonce, KS 0 is the public key of the first server and C o is the encrypted nonce.
When the mobile agent wants to take data X i with it from a certain server S i , the mobile agent asks the respective server S i to sign the data X i with its private key. Thus, a new checksum is being calculated which can be described by the following mathematical term:
C i ={C i−1 ,[X i ]PKS i ,S i }KS 0 (6)
wherein C i describes the i'th checksum, C i−1 the i−1'th checksum, X i the data the mobile agent wants to take with it from the server S i , PKS i the private key of server S i , S i a server code of the server S i , and KS 0 the public key of the first server from which the mobile agent is sent out.
The mobile agent carries now the data which it takes from different servers on its route through the network system and the actual checksum which is calculated successively on the different servers. The data may be kept in a data container. The data the mobile agent takes with it remain visible to the other servers. If one wants to prevent this, one can encrypt the data with the public key of the first server. When the mobile agent returns home, i.e. to the first server, it can be checked by the first server if the mobile agent has been modified on its route through the network system. To do this one proceeds in the other direction by deflating the checksum and verifying the signature on the data which can be described by the following mathematical term:
{C i }PKS 0 =C i−1 ,[X i ]PKS i ,S i (7)
wherein C i is the i'th checksum, PKS 0 is the private key of the first server, C i−1 is the i−1'th checksum, X i is the data the mobile agent has gathered from the server S i , PKS i is the private key of server S i and S i is a server code of server S i itself.
When at a certain point a verification of the signature fails the data that has been checked so far can be regarded as trustable, but the data further contained in the remaining checksum cannot be trusted anymore. When finally the whole checksum has been successfully deflated, one should get the nonce N o so that it is certain that the data container is part of the mobile agent and it is not the data container of another mobile agent.
This described method also makes use of classic cryptographic techniques to protect a data transfer of a mobile agent. However, since the mobile agents migrate from one server to another before returning to their home server, the mobile agents need additional protection. This will become clear from the description of the following attack.
It is assumed in the following that a first server S 0 sends out a mobile agent which is intended to reach a specific server B. On its way through the network the mobile agent from server S 0 arrives at an intermediary server E. It is supposed that server E gets the mobile agent from server S 0 and that server E knows an old value of a checksum C i of a sequence of checksums C 1 to C n wherein i is smaller that n. This is possible for example if there is a loop in the route of the mobile agent on its way through the network system or if server E collaborates with another server where the mobile agent already went on its route through the network. Server E can now just starting from the i'th element, leave elements out of the data container, change or add elements in the name of other servers. To do this server E makes its own mobile agent that carries a message X i+1 with it that server E wants to add at the i+1'th position and its own data container. Server E sends its own mobile agent with program code PE together with the checksum C i to server B which can be described as follows:
E=>B:PE,X i+1 ,C i (8)
The mobile agent of server E asks server B to sign the data with its private key and to calculate a new checksum C i+1 and to give it back to the mobile agent which then returns back to server E which can be described as follows:
B=>E:PE,C i+1 ={C i ,[X i+1 ]PKB,B}KE (9)
wherein PE is the program code of the mobile agent of server E, PKB is the private key of server B, KE is the public key of server E, C i+1 and C i are the respective checksums and X i+1 are the data server E wants to add at the i+1'th position.
That means that server E sends its mobile agent to server B in order to let server B add the message X i+1 to the data container. When the mobile agent gets back home to server E, server E decrypts the checksum with its private key and encrypts it again with the public key from server S 0 . Server E can in this way continue until it is satisfied with the result. Then it can release the mobile agent from server S 0 with the forged data container and send it back to server S 0 which can be described as follows:
E=>S 0 :PS 0 ,C i+1 ={C i ,[X i+1 ]PKB,B}KS 0 (10)
wherein PS 0 is a program code of the mobile agent from server S 0 , KS 0 is the public key of server S 0 , and C i+1 and C i are the respective checksums. Server S 0 has no possibility to detect the malicious behavior of server E.
In the following, two possible methods are described generally, wherein each method meets one of the above mentioned problems, respectively.
In order to make sure that one can check if the data the agent is carrying with it are really this agent's data and do not belong to another agent, a method as proposed in European Patent application number 06 290 878.5 can be provided, the method comprising at least the following operations:
choosing a unique number and assigning it to the mobile agent, choosing a secret symmetric key and assigning it to the data to be protected, encoding the secret key with the second server's public key, encrypting the secret key and the first server's public key via a wrapping function, thus forming a data authentication code, encoding the data with a secret key, and combining the unique number, the encoded data, the encoded secret key and the data authentication code and encoding that combination with the first server's private key, thus forming a nested structure to be decoded successively for access to the data.
According to a possible embodiment of the method, the nested structure to be decoded for access to the data is defined as follows:
[PA,r0,{SKo}KB,h(KA,SKo),{mB}SKo]PKA (11)
wherein PA is a agent's program code, r0 is the unique number, SKo is the secret key, KB is the second server's public key, h is the wrapping function, such as a hash function, KA is the first server's public key, PKA is the first server's private key and mB is the data to be protected.
Coming back to the exemplary attack mentioned before, the same scenario can be described and the attack as described before can be avoided by means of the method according to a possible implementation as follows:
When the mobile agent arrives at a server of user B, user B verifies first the private key associated with the mobile agent, representing at the same time a signature from a user A as the owner of the mobile agent on the whole data structure which has been received by the server of user B. Then user B decrypts the secret symmetric key, called here SKo, with its private key, called here PKB. Then user B checks the message authentication code, that means the hash function value h of the public key KA from user A, namely the public key associated with the mobile agent, and the secret symmetric key SKo. Finally user B decrypts the message mB and makes it available to the mobile agent, if appropriate.
The attack described before is not possible anymore since user E does not know the secret symmetric key SKo and cannot forge the hash value h(KA, SKo). User E can remove again the signature of user A, namely the private key PKA associated with the mobile agent and can replace it by its own private key PKE. Furthermore, user E can replace the mobile agent code of user A by the mobile agent code of its own agent represented by PE. Therefore, user E can send to user B the following:
E=>B:[PE,r0,{SKo}KB,h(KA,SKo),{mB}SKo]PKE (12)
Since the public key KA does not match with the private key PKE of user E with which user E signed the data structure, the verification of the hash function value h(KA, SKo) by user B will fail and user B will not decrypt the message mB and thus does not make it available to the mobile agent of user E.
According to a further possible embodiment of the method, the unique number is used only once and is calculated on the basis of a program code of the mobile agent. Therefore, the data structure contains a unique number, in the above-mentioned case called r0, that will be used only once and is calculated on the basis of the program code of the mobile agent, represented in the above mentioned case by PA. Every time a user sends out a new mobile agent the user changes that unique number. This number is introduced because if not, it could be possible that an old mobile agent of a specific user can be reused. If user A for example sends out a mobile agent to change data about him that are kept at user B, then someone would be able to reuse an old mobile agent of user A to change the data back into the old data.
It is possible that user B maintains a list of numbers that have already been used. Therefore, user B has a control that no number can be reused, and therefore, an already used agent cannot be reused again.
According to a further possible embodiment of the method, the program code of the agent is maintained in a Java Archive file. Furthermore, it is possible that that Java Archive file is signed by the private key associated with the mobile agent which is the private key of the mobile agent's owner.
It is also possible that the Java Archive file contains the unique number assigned to the mobile agent.
The complete structure to be decoded can be defined as follows:
[PA,r0]PKA+[r0,{SKo}KB,h(KA,SKo),{mB}SKo]PKA (13)
wherein PA is an agent's program code, r0 is the unique number, SKo is the secret symmetric key, KB is the second server's public key, h is the wrapping function, KA is the first server's public key, PKA is the first server's private key and mB is the data to be protected. The reason why the Java Archive file may also contain the unique number is because the agent's program code and the value of the objects, i.e. the data of the mobile agent, can be serialized separately in existing agent platforms.
In order to meet the second problem, namely to add data that a mobile agent from a first server finds on a i'th server of a number of servers the mobile agent has to pass according to an appropriate succession to a secure data container, a method can be applied as proposed in another previous European Patent application number 06 290 876.9, the method comprising the following operations:
receiving the mobile agent which has been prepared by the first server by choosing a unique number and assigning it to the mobile agent, encoding the chosen unique number with the private key of the first server, thus forming an agent specific initialization number as basis for a sequence of checksums to be computed successively by the number of servers, and sending the mobile agent together with its initialization number on its route through the network system for processing the order passing thereby the number of servers successively, encoding in case that the mobile agent intends to take data with it when passing the i'th server the initialization number together with the data with the i'th server's private key and computing therewith a new server specific checksum using the public key of the first server and the checksum computed by the server right before in the succession, and sending the mobile agent further to the next server within the succession.
According to a possible embodiment of the method the data the mobile agent takes with it from servers on its route through the network is encoded by the public key of the first server. Thereby, it can be avoided that the data remains visible to other servers when the mobile agent is on its route through the network system.
Furthermore, it is possible that the sequence of checksums is defined by the following functional rule:
C i ={C i−1 ,[X i [r0]PKS 0 ]PKS i ,S i }KS 0 (14)
wherein C i is the i'th checksum, X i is the data from the i'th server, r0 is the unique number, PKS 0 is the private key of the first server, KS 0 is the public key of the first server, PKS i is the private key of the i'th server, S i is a code number of the i'th server, and i is a positive integer value.
It is assumed that the mobile agent has to pass for processing its order a succession of n servers S 1 , . . . , S n , wherein n is a positive integer value. In the functional rule described above, i should be smaller or equal to n. r0 is the unique number which has not to remain secret. [r0]PKS 0 corresponds to a signature from the first server from which the mobile agent is sent out.
Coming back to the exemplary attack mentioned before, the same scenario can be described and the attack as described before can be avoided by means of an implementation as follows:
When a mobile agent wants to take data with it from a certain server S i , the new checksum C i is, as already described, the following:
C i ={C i−1 ,[X i ,[r0]PKS 0 ]PKS i ,S i }KS 0 (15)
It is clear that the previously described attack is not possible anymore. It is supposed again that server E gets the mobile agent from the first server S 0 and that server E knows an old value of the checksum C i with i<n. This is possible, as already indicated before, if there is, for example, a loop in the route of the mobile agent or if server E collaborates with another server where the mobile agent already went. If server E uses the checksum C i and the unique number from server S 0 in its own mobile agent, then the unique number r0 gets signed with the private key of server E which is described by [r0]PKE. Server B which is asked by the mobile agent from server E to compute a new checksum by adding the data X i+1 will determine the checksum as follows:
C i+1 ={C i ,[X i+1 ,[r0]PKE]PKB,B}KE (16)
In the originally proposed method the data container was initialized with {N 0 }KS 0 to be able to check in the end if the data container truly belonged to this respective mobile agent and to prevent a server of generating its own data container. This mechanism was flawed. By using the new computational rule for computing the checksum this can be avoided. When server E receives the checksum it replaces its public key KE by the public key KS 0 of the first server. Since the signature from server E, namely [r0]PKE is further signed by the private key PKB of server B when computing the new checksum C i+1 , and further server E does not know the private key of the first server, server E is not able to erase its private key PKE from the checksum, thus leaving a kind of fingerprint. Therefore, when server E sends the mobile agent from server S 0 together with the falsified data and the new checksum C i+1 back to server S 0 , server S 0 will immediately recognize that the data container is not part of its own mobile agent, but the data container of another agent. Finally, server S 0 can be sure that the data it gets by its own mobile agent have been tampered by any server on the mobile agent's route through the network.
It is possible that the unique number r0 which does not have to remain secret corresponds to a process identification number. That means that the chosen unit number can be at the same time associated to a specific order or process the mobile agent has to execute on its route through the network.
It is also possible that each checksum is deflated for verifying successively the respective keys on the data thus checking the unaffected and correct processing of the order.
Apart from such provisions in order to prevent the above mentioned kinds of attacks, it may further be necessary to provide a mechanism that guarantees that a certain number of previously defined servers are being visited by the mobile agent on its route through a corresponding network system. Therefore, it would be appropriate to protect the path of a mobile agent.
Thereby, the following mechanism to protect the path of the mobile agent can be considered. Before the mobile agent is sent out from the first server S A , the path of the mobile agent is encrypted in the following way:
wherein ip(S i ) is the ip-address of server S i , t is a unique number, and “End” denotes the end of the path of the mobile agent.
Thus, the path contains the encrypted addresses of the servers that the mobile agent will visit and digital signatures to protect the integrity of the path. The path is encrypted in a nested format.
When the mobile agent arrives at server S i , server S i decrypts the internet addresses of its predecessor ip(S i−1 ) and of its successor ip(S i+1 ), the digital signature and the rest of the encrypted path that now becomes the new data structure of the route.
The digital signatures are calculated based on a unique number t, this is necessary to prevent replay attacks. They also contain the ip-addresses of the current server S i , of the previous server S i−1 and the next server S i+1 . The rest of the path is also signed.
Based on “End” the server S n can decide if it is the endpoint of the path. Thus, “End” is a configuration value. Mostly, the mobile agent will return to the first server where the mobile agent departed. The digital signatures are included in the encrypted part, to keep the path secret.
By encrypting the path in a nested format, the following attack can be prevented. Thereby, it is assumed that the original path of the mobile agent contains two servers S i and S j , that are not located one immediately after the other (i.e., j>i+1). Then the server S i can send a copy of the path to S j when the mobile agent is located on the server S i . The server S j can check so far if it is in the path of the mobile agent by trying to decrypt with his private key in a sequential way the data of the path. If in one of the attempts it is capable of obtaining the cleartext, then server S j knows that it is in the path. In this case server S j informs server S i about this, and server S i can then send the mobile agent immediately to server S j , whereby the servers between S i and S j are not visited by the mobile agent. No server after S j can detect this kind of attack.
By using the nested format as described before, this kind of attack is not possible anymore, because the path is calculated one step at a time. Because of the nested encryption of the path the servers have to be visited in the right order. In each step the address of the following server is decrypted and the remaining information of the path is still encrypted with the public key of the next server. If the verification of the signature by server S i is successful, S i can be certain that it was included in the original path, that the mobile agent comes from the correct predecessor, that the address of the following server S i+1 is correct and that all further data in the path cannot be changed.
An attack that cannot be prevented by this scheme is the following. A server S i can send information about a mobile agent, for example its identity, to all servers that are cooperating with that server S i . If the mobile agent later on by coincidence arrives at one of these servers, then the mobile agent can be resetted to its old state when it still was at server S i and bypassed all the servers in between, as described before. Server S i has to save a copy of the mobile agent, however, in order to reuse it later on.
SUMMARY
Therefore, it would be appropriate to provide a method to prevent all of the previously described attacks at once.
According to one aspect, a method is provided for protecting data and path of a mobile agent from a first server within a network system with a plurality of servers, at least a number of which the mobile agent has to pass according to an appropriate succession which defines the path of the mobile agent, wherein the path and data intended for any one of the servers are jointly encrypted within a nested structure, the nested structure being built up on a number of nested terms corresponding to the number of servers, each nested term being decryptable in the given succession by exactly one server of the number of servers in such a manner that each server of the numbers of servers gets access only to the data intended for it and to a section of the path enclosing it, respectively.
It is possible that the method wherein each of the plurality of servers has a pair of a public key and a private key and an ip-address, respectively, comprises, starting from the first server, at least the following operations:
choosing a unique number and assigning it to the mobile agent, choosing for each server the mobile agent has to pass a secret symmetric key, respectively, and assigning it to that respective server, encoding each secret key with the public key of the respective server, encrypting each secret key and the public key of the first server via a wrapping function, thus forming for each respective server an authentication code, encoding via a recursive workflow the data and the path jointly in a nested structure consisting of a number of nested terms corresponding to the number of servers, the workflow starting by encoding as kernel of the innermost term the data intended for the last server in the succession with the last server's secret key, combining the unique number, that innermost term's kernel, the encoded respective secret key, the respective data authentication code and the ip-address of the last server and the ip-address of the second last server and encoding that combination with the private key of the first server, thus forming the innermost term and serving combined with the ip-address of the last server and the data intended for the second last server as kernel of the second innermost term in the nested structure, and continuing accordingly by generating successively the terms of the nested structure correspondingly to the innermost term.
It is possible that the wrapping function is chosen as a hash function.
In another aspect, each of the nested terms to be decoded by the respective server for access to the respective data is defined according to the following scheme:
Data_S i =[r0,ip(S i−1 ),ip(S i ),{S i Ko}KS i ,h(KS 0 ,S i Ko),{m′ i }S i Ko]PKS 0
wherein r0 is the unique number, S i Ko is the respective server's secret key, KS i is the respective server's public key, h is the wrapping function, KS 0 is the first server's public key, PKS 0 is the first server's private key and m′ i is the i'th term of the nested terms which is defined as follows:
m′ i =m i ,ip(S i+1 ),Data_S i+1
wherein i is a positive integer value, m i is the data intended for the i'th server S i .
The data of the nested path scheme is added hereby to the other data that are targeted to the different servers on the path. The unique number t, which has already been introduced before, corresponds to the unique number r0.
Thus, the mechanism to protect the data of the mobile agent becomes now a nested data structure.
According to a further aspect, the unique number is used only once and is calculated on basis of a program code of the mobile agent.
It is also possible that the program code of the mobile agent is maintained in a Java Archive file.
The Java Archive file can be signed by the first server's private key.
Furthermore, the Java Archive file can contain the unique number assigned to the mobile agent.
Moreover, the agent's program code and the data of the agent can be serialized separately.
In another aspect, the unique number can be used by the servers for registration in a list of numbers, thus keeping a check on the numbers that have already been used.
In another implementation, the method further comprises, starting from the first server, the following operations:
choosing a unique number and assigning it to the mobile agent, encoding the chosen unique number with the private key of the first server, thus forming an agent specific initialisation number as basis for a sequence of checksums to be computed successively by the number of servers, and sending the mobile agent together with its initialisation number on its route through the network system passing thereby the number of servers successively, so that each server when being passed by the mobile agent encodes the initialisation number together with data to be added at that respective server with that server's private key and computes therewith a new server specific checksum using the public key of the first server and the checksum computed by the server right before in the succession, and sends the mobile agent together with the new checksum further to the next server within the succession.
In one possible aspect, the sequence of checksums is defined by the following functional rule:
C i ={C i−1 ,[X i [r0]PKS 0 ]PKS i ,S i }KS 0
wherein C i is the i'th checksum, X i is the data to be added at the i'th server, r0 is the unique number, PKS 0 is the private key of the first server, KS 0 is the public key of the first server, PKS i is the private key of the i'th server, S i is a code number of the i'th server, and i is a positive integer value.
It is possible that the unique number is a process identification number.
According to another implementation, each checksum is used to be deflated by the first server for verifying successively the respective keys on the data thus checking the unaffected completion of the full path when the mobile agent returns back to the first server.
In another aspect, a system is provided which comprises at least a first server and a mobile agent from said first server, the first server having a pair of a private key and a public key and an ip-address, the system is further coupled with a plurality of servers, at least a number of which the mobile agent has to pass according to an appropriate succession which defines a path of the mobile agent, wherein each of the plurality of servers has a pair of a public key and a private key and an ip-address, respectively, and the mobile agent is configured to provide its path and data intended for any one of the servers jointly within a nested structure, the nested structure being built up on a number of nested terms corresponding to the number of servers.
It is possible that the nested structure can be computed by the first server which sends the mobile agent out.
In a possible aspect, each of the nested terms to be decoded by the respective server for access to the respective data is defined according to the following scheme:
Data_S i =[r0,ip(S i−1 ),ip(S i ),{S i Ko}KS i ,h(KS 0 ,S i Ko),{m′ i }S i Ko]PKS 0
wherein i is a positive integer value, r0 is a unique number, ip(S i ) and ip(S i−1 ) are the respective ip-addresses of servers S i and S i−1 , respectively, S i Ko is a respective server's secret key, KS i is the respective server's public key, h is a wrapping function, KS 0 is the first server's public key, PKS 0 is the first server's private key, and m′ i is the i'th term of the nested terms, which is defined as follows:
m′ i =m i ,ip(S i+1 ),Data_S i+1
wherein ip(S i+1 ) is the respective ip-address of server S i+1 , and m i is the data intended for the i'th server S i .
It is possible that the unique number is used only once and is calculated on the basis of a program code of the mobile agent. The program code of the mobile agent can be maintained in a Java Archive file. Thereby, the Java Archive file can be signed, as already mentioned, by the first server's private key. Moreover, the Java Archive file can contain the unique number assigned to the mobile agent.
According to another implementation, the agent's program code and the data of the mobile agent are serialized separately.
According to a further aspect, each of the plurality of servers is configured to receive the mobile agent which has been prepared by the first server by encoding the chosen unique number with the private key of the first server, thus forming an agent specific initialisation number as basis for a sequence of checksums to be computed successively by the number of servers, and sending the mobile agent together with its initialisation number on its route passing thereby the number of servers successively, to encode when being passed the initialisation number together with data to be added at said server with said server's private key and to compute therewith a new server specific checksum using the public key of the first server and the checksum computed by the server right before in the succession, and to send the mobile agent further to the next server within the succession.
It is possible that the sequence of checksums is defined by the following functional rule:
C i ={C i−1 ,[X i ,[r0]PKS 0 ]PKS i ,S i }KS 0
wherein C i is the i'th checksum, X i is the data to be added at the i'th server, r0 is the unique number, PKS 0 is the private key of the first server, KS 0 is the public key of the first server, PKS i is the private key of the i'th server, S i is a code number of the i'th server, i is a positive integer value.
In another aspect, a computer program product is provided with a computer-readable medium and a computer program stored on the computer-readable medium with a program code which is suitable for carrying out a method for protecting data and path of a mobile agent from a first server as described before when the computer program is run on a computer.
Another implementation provides a computer program with a program code which is suitable for carrying out a method for protecting data and path of a mobile agent from a first server as described before when the computer program is run on a computer.
A computer-readable medium with a computer program stored thereon is also provided, the computer program comprising a program code which is suitable for carrying out a method for protecting data and path of a mobile agent from a first server as described before when the computer program is run on a computer.
Implementations can be used in an e-business scenario for travel management for example on top of a so-called SAP NetWeaver™ platform. When someone wants to plan a trip, he first checks the web pages of some airline companies for the price of a flight, to pick the cheapest one out. Besides that airplane ticket one would also need to rent a car and a hotel for the trip. In reality, most airline companies have special deals with hotels and car rental services. The check for the cheapest combination of an airplane ticket, hotel and car rental is very time consuming for most people. By using a mobile agent, it is possible to automate this search. It is needed a mobile agent that carries the data of the trip with it and looks on the different agent-enabled SAP NetWeaver™ platforms for the needed information. Data that are sensitive for customers can now be protected by using an embodiment of the method, or by using an embodiment of the mobile agent. Data which are sensitive for customers can be for example credit card information, fidelity numbers, etc.
Further features and embodiments will become apparent from the description and the accompanying drawings.
For the purpose of clarity, the present discussion refers to an abstract example of a network system. However, implementations of the method and the system may operate with a wide variety of types of network systems including networks and communication systems dramatically different from the specific example as illustrated in the following drawings.
It should be understood that while details of one or more implementations are described in terms of a specific system, further implementations may have applications in a variety of communication systems, such as advanced cable-television systems, advanced telephone-networks or any other communication systems that would benefit from the system or the method. It is intended that the system as used in this specification and claims is realizable within any communication system unless the context requires otherwise.
Implementations are schematically illustrated in the drawings by way of an example embodiment and explained in detail with reference to the drawings. It is understood that the description is in no way limiting and is merely an illustration of various implementations.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a possible scheme for protection of a path of a mobile agent which may be vulnerable to an attack as it is known from the prior art.
FIG. 2 shows a possible scheme for protection of the path of a mobile agent as it can be realized by a possible embodiment of a method according to one implementation.
FIG. 3 shows an e-business scenario in which an embodiment of a method according to another implementation can be used.
FIG. 4 shows a possible scenario of a data transfer by a mobile agent as it can be realized within a possible embodiment of a system according to one implementation.
DETAILED DESCRIPTION
FIG. 1 shows a mechanism to protect a path of a mobile agent as it is already known in the prior art. Before a mobile agent is sent, the path of the mobile agent is encrypted according to the formula as shown in FIG. 1 . The encrypted path r has a nested structure, consisting of nested terms. The number of nested terms corresponds to the number of servers S i which are to be visited by the mobile agent on its route. The mobile agent MA is sent out from a server S 0 . The server S 0 has a private key PKS 0 and a corresponding public key KS 0 . Furthermore, the server S 0 has an ip-address ip(S 0 ). Each server S i of the number of servers also has a private key PKS i , a corresponding public key KS i and an ip-address ip(S i ). t is a unique number. “End” denotes the end of the path of the mobile agent MA.
Therefore, the encrypted path r contains the encrypted ip-addresses of the respective servers that the mobile agent will visit. Thereby, the path determines a specific order according to which the servers are to be visited by the mobile agent. Moreover, the encrypted path r comprises digital signatures to protect the integrity of the path of the mobile agent.
When the mobile agent MA arrives at a server S i , the encrypted path has already been partly decrypted by the servers S j , j=1, . . . , i−1, which have already been visited by the mobile agent as determined by the path itself. Therefore, the term to be decrypted by server S i can be described as follows:
{ . . . }KS i ={ip(S i−1 ),ip(S i+1 ),[ip(S i−1 ),ip(S i ),ip(S i+1 ),t,{ . . . }KS i+1 ]PKS 0 }KS i
Therefore, S i can decrypt by means of its private key PKS i the ip-address ip(S i−1 ) of its predecessor S i−1 and the ip-address ip(S i+1 ) of its successor ip(S i+1 ). Moreover, it can decrypt the digital signature, thus, getting to know the data structure ip(S i−1 ),ip(S i ),ip(S i+1 ),t, { . . . }KS i+1 . However, the portion { . . . }KS i+1 , remains encrypted and becomes the new data structure of the route, i.e. of the remaining path.
The signatures are calculated based on the unique number t in order to prevent replay attacks. The signatures also contain the ip-address of the current server S i , the previous server S i−1 and the next server S i+1 . Based on “End”, server S n can decide if it is the endpoint in the path. Mostly, the mobile agent will return to the server S 0 where the mobile agent departed. The signatures are included in the encrypted part, to keep the path secret.
Because of the nested encryption of the path the servers have to be visited in the right order. If the verification of the signature by server S i is successful, S i can be certain that it was included in the original path, that the mobile agent MA comes from the correct predecessor S i−1 , that the address of the following server S i+1 is correct and that all further data in the path cannot be changed.
However, an attack that cannot be prevented by this scheme is described in the following. A server S i can send information about an agent, for example its identity, to all servers that are cooperating with server S i . If the agent later on, by coincidence, arrives at one of these servers, then the mobile agent MA can be reset to its old state as if the mobile agent were still at server S i and bypassed all the servers in between. That means, e.g. that all data the mobile agent actually took with it since it departed from server S i would be lost. For this purpose server S i has to save a copy of the mobile agent MA in order to reuse it later on.
FIG. 2 describes a scheme to protect a path of a mobile agent according to a possible embodiment of a method according to one aspect. In order to protect the path of the mobile agent, the principle of nested encryption is used. This approach is combined with a mechanism to protect data of the mobile agent as described in the European Patent application number 06 290 878.5.
The data of the path and the data that are targeted to different servers on the path of the mobile agent are jointly encrypted within a nested structure which can be presented by the formula as shown in FIG. 2 . All data of the mobile agent as well as the path the mobile agent intends to trace are protected in one go. The ip-addresses used to describe the path and the data represented by m i are coupled and appropriately encrypted.
When the mobile agent MA arrives at server S i , server S i verifies first the private key, namely the signature from server S 0 on the whole data structure. Then server S i decrypts the secret symmetric key S i Ko with its private key PKS i . Then server S i checks the message authentication code, namely the hash value h of the public key KS 0 from server S 0 with the secret symmetric key S i Ko. Finally server S i decrypts the data m′ i and makes it available to the mobile agent MA if appropriate. Thereby, the ip-address of the following server S i+1 as well as the data m i which is targeted to server S i becomes available. From Data_S i+1 , which is also comprised within m′ i , server S i gets no more information since S i has no access to the secret key S i+1 Ko. Therefore, server S i cannot see the full path or all data of the mobile agent. The fact that no server on the path of the mobile agent can see the full path that the mobile agent should follow can be convenient with respect to privacy of information.
In order to prevent that server S i can send information about the mobile agent to all servers that are cooperating with server S i so that those servers can reset the mobile agent when the mobile agent arrives at one of these servers, it can be further foreseen to add the data to the mobile agent in a secure way as proposed in European Patent application number 06 290 876.9. The introduction of a checksum can be used in order to guarantee that any undesirable intervention of a server can be detected. Such a checksum which has to be computed by each server S i that the mobile agent visits on its path and which is given to the mobile agent to take with it on its further route can be defined by the following functional rule:
C i ={C i−1 ,[X i [r0]PKS 0 ]PKS i ,S i }KS 0
wherein C i is the i'th checksum, X i is the data to be added at the i'th server, r0 is the unique number, PKS 0 is the private key of the first server, KS 0 is the public key of the first server, PKS i is the private key of the i'th server, S i is a code number of the i'th server, and i is a positive integer value.
It can be envisaged that every time the mobile agent reaches a server S i , the server S i has to add its identity at the least to the secure data container, even if no other data are collected at that server. This way it is possible to check when the mobile agent is back home if the mobile agent has completed its full path.
FIG. 3 shows a specific e-business scenario for a travel management on top of a so-called SAP NetWeaver™ platform. It is assumed that someone wants to plan a trip. In this case he first checks the web pages of some airline companies for the price of the flight he wants so he can pick out the cheapest one. In the case shown here the traveler constructs by means of server A as the Home server “Home” a mobile agent MA called here “MyTravelAgent”. The data structure which is carried by the mobile agent MA corresponds here to:
Data_B=[r0,ip(A),ip(B){S B Ko}KB,h(KA,S B Ko),{Nice,Frankfurt,Amex:374923335610,Frequent Flyer 2334765,ip(C),Data_C}S B Ko]PKA
where r0 is a unique number, ip(A) is the ip-address of server A as the Home server, and ip(B) is the ip-address of a server B to which the mobile agent is sent first. In the case shown here server B corresponds to the server of the airline Airfrance. S B Ko is a secret symmetric key which is assigned to and known by server B. KA is a public key and PKA a private key of server A as the home server of the traveler.
The mobile agent MA migrates now from one server to another in order to get enough information for the trip to be planned by the traveler. Besides an airplane ticket the traveler would also need to rent a car and a hotel for the trip. In reality most airline companies have special deals with hotels and car rental services. The check for the cheapest combination of airplane ticket, hotel and car rental is too time consuming for most travelers. By using the mobile agent MA the traveler can automate this search. The mobile agent MA looks now on its route through the network system on the different agent enabled SAP NetWeaver™ platforms for the needed information. The order of the servers which are to be visited by the mobile agent defines the path of the mobile agent which can be described by the respective ip-addresses of the servers. The path is also encompassed by the nested data structure Data_B. The data which is carried by the mobile agent MA and which should be not accessible to any server within the network is {Nice, Frankfurt, Amex: 374923335610, Frequent Flyer 2334765, ip(C), Data_C} since those data are sensitive for the traveler, particularly for example a credit card information and further fidelity numbers. This data can be partly decrypted by server B. First mobile agent MA starts from server A and is sent to server B. In order to get information about the request of the traveler, server B has to handle the data element Data_B accordingly. First server B can verify the digital signature of server A, namely the private key PKA by means of the public key KA. Then server B decrypts the secret symmetric key S B Ko with its private key PKB. By means of the secret symmetric key S B Ko server B can check the message authentication code, namely the hash value h of the public key KA of server A. Finally server B decrypts the data {Nice, Frankfurt, Amex: 374923335610, Frequent Flyer 2334765, ip(C), Data_C} by means of the secret symmetric key. Thereby server B gets to know that the traveler wants to book a flight from Nice to Frankfurt, that his Amex number is 374923335610, and that the traveler is the frequent flyer 2334765. Moreover, due to the ip-address ip(C), server B gets to know the next server the mobile agent has to visit. Besides the information server B needs to give any further information about the request of the traveler, namely about the flight from Nice to Frankfurt, server B also gets to know the ip-address of the next server C to which the mobile agent is to be sent next. In the case shown here server C corresponds to the server of the car rental company Sixt. The rest of the path the mobile agent has to trace is included in the encrypted data element “Data_C”. The data element Data_C is not further decryptable by server B. This element is structured comparably as the data element “Data_B” decryptable by server B. Therefore, regarding the whole path of the mobile agent, there results a nested data structure. Data_C is partly decryptable by server C so that server C gets information targeted to it in order to contribute in processing the request of the traveler.
From server B as the server of the airline company Airfrance, the traveler gets some information about a price of a flight from Nice to Frankfurt which is about 130 euros and further information about special deals the airline Airfrance has with the hotel Dorint and with car rental services Sixt and Hertz.
Then the mobile agent MA migrates further to server C as the server of the car rental service Sixt. The data element Data_C can further be handled by server C. The traveler gets here information about different cars and the corresponding rental costs, namely about Audi which costs 40 euros per day and Mercedes which costs 50 euros per day. The mobile agent MA collects all this information and migrates further to the server of the car rental service Hertz where it gets the information about the rental costs of Ford which costs 15 euros per day. With all this collected information the mobile agent MA travels further to the server of the hotel Dorint in order to get now the complete information for a trip when it is made by using the airline Airfrance and one of the hotels and car rental services with which the airline company Airfrance has special deals.
In order to get information about an alternative airline company, the mobile agent travels further through the network to the server of the airline company Lufthansa. On this server it gets information about the flight from Nice to Frankfurt which costs about 115 euros. The Lufthansa company has a deal with the car rental services Sixt and Hertz and with the hotels Dorint and Queens. The mobile agent MA can get now more information on the respective servers of the car rental services and the hotels in order to get a complete statement of costs for the traveler when either using the airline company Airfrance or the airline company Lufthansa. Finally, the mobile agent MA returns back to server A with a detailed catalogue of statements of costs about different alternatives for planning the trip from Nice to Frankfurt. In order to avoid that the mobile agent MA is vulnerable to so-called cut-and-paste attacks when the mobile agent MA migrates from one server to another its path as well as the data it carries with it, particularly the sensitive data of the traveler, as for example the credit card information and further fidelity numbers, are protected as proposed by term Data_B. Thus, no unauthorized server can get access to the sensitive data of the traveler. Furthermore, no server can see the full path that the mobile agent should follow. This can be quite convenient with respect to privacy of information.
FIG. 4 shows a possible scenario of a data transfer by a mobile agent as it can be realized within a possible embodiment of the system according to one implementation. The scenario shown in FIG. 4 shows a plurality of servers S 0 , . . . , S n which are to be passed by a mobile agent according to a pregiven succession. That succession can be pregiven by the first server S 0 which sends the mobile agent out. This succession defines the path the server has to follow on its route through the network. In the case shown here it is assumed that the mobile agent has to pass the individual servers in an ascending order indicated by their respective index. It is further assumed that each of the servers of the plurality of servers has a private key and a public key and an ip-address, respectively. That means that server S i has a public key KS i and a private key PKS i and an ip-address ip(S i ). The same applies to all the other servers indicated by the corresponding index, respectively. Before sending the mobile agent on its way from server S 0 to the next server S 1 , server S 0 composes the path of the mobile agent and data intended for anyone of the servers in a nested format according to the following scene:
Data_S 1 =[r0,ip(S 0 ),ip(S 1 ),{S 1 Ko}KS 1 ,h(KS 0 ,S 1 Ko),{m′ 1 }S 1 Ko]PKS 0 ,
wherein m′ 1 =m 1 , ip(S 2 ), Data_S 2 , r0 is an arbitrary unique number, S 1 Ko is a secret symmetric key assigned to server S 1 , h is a cryptographic hash function, and m 1 describes the data intended for server S 1 .
When the mobile agent arrives for example at server S i after having passed all servers S 1 , . . . , S i−1 , server S i verifies first the private key, namely the signature from server S 0 on the whole data structure Data_S i . Then server S i decrypts the secret symmetric key S i Ko with its private key PKS i . Then server S i checks the message authentication code, namely the hash value of the public key KS 0 from server S 0 with the secret symmetric key S i Ko. Finally server S i decrypts the data m′ i and makes it available to the mobile agent. The mobile agent therefore has access to the data m i intended for server S i . Furthermore, the mobile agent gets to know the ip-address of server S i+1 which the mobile agent has to visit next according to the pregiven succession. Data_S i+1 is the encrypted data the mobile agent has to take with it on its further path to the next server S i+1 .
It is assumed, in the following, that server S i sends the mobile agent not to the next server S i+1 but to a server S j , wherein j>i+1. It will be shown in the following that server S j is not able to get access to the information the mobile agent takes with it. When the mobile agent arrives at server S j directly from server S i , the mobile agent takes with it the data structure Data_S i+1 as described in FIG. 4 . The server S j can decode by means of the public key of server S 0 the signature of server S 0 , but server S j is not able to get access to the secret symmetric key S i+1 Ko, since server S j does not know the private key of server S i+1 . Therefore, server S j only gets to know the ip-addresses of server S i and server S i+1 , but no information about the data the mobile agent takes with it, since this data is further encrypted within the term m′ i+1 . Therefore, server S j has no effective benefit from the mobile agent. Server S j is not able to exert influence on the mobile agent's path and the data the mobile agent takes with it since the path as well as the data are encrypted jointly within the nested structure as described in FIG. 4 .
In order to avoid that any server, which gets to know the identity of the mobile agent from another server, can reset the mobile agent to an older state when it still was at a previous server and bypassed all the servers in between, it can be foreseen that every server within the succession the mobile agent has to pass has to add its identity at the least to the secure data container by means of the mechanism of checksums as described before. Thus, one can check when the mobile agent is back home, if the mobile agent has completed its full path.
Implementations of the various techniques described herein may be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. Implementations may implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, e.g., in a machine-readable storage device or in a propagated signal, for execution by, or to control the operation of, data processing apparatus, e.g., a programmable processor, a computer, or multiple computers. A computer program, such as the computer program(s) described above, can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network.
Method steps may be performed by one or more programmable processors executing a computer program to perform functions by operating on input data and generating output. Method steps also may be performed by, and an apparatus may be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit).
Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. Elements of a computer may include at least one processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer also may include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory may be supplemented by, or incorporated in special purpose logic circuitry.
To provide for interaction with a user, implementations may be implemented on a computer having a display device, e.g., a cathode ray tube (CRT) or liquid crystal display (LCD) monitor, for displaying information to the user and a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input.
Implementations may be implemented in a computing system that includes a back-end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front-end component, e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an implementation, or any combination of such back-end, middleware, or front-end components. Components may be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (LAN) and a wide area network (WAN), e.g., the Internet.
While certain features of the described implementations have been illustrated as described herein, many modifications, substitutions, changes and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the scope of the embodiments.
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Secure message transfer of at least one message from a sender to a receiver within a network system may be provided. For example, a message structure information regarding the at least one message may be computed on a sender-side and according to a pre-given scheme. The computed message structure information may be added as message account information into the at least one message to be sent. The message account information may be protected by a signature. The at least one message may be transferred through the network system to the receiver. On a receiver-side, the message account information may be validated after reception of the at least one message and according to the pre-given scheme.
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TECHNICAL FIELD
[0001] This disclosure relates to a battery pack for an electrified vehicle. The battery pack includes an electronics umbrella configured to channel moisture away from one or more electronics modules housed inside the battery pack.
BACKGROUND
[0002] The desire to reduce automotive fuel consumption and emissions is well documented. Therefore, vehicles are being developed that reduce or completely eliminate reliance on internal combustion engines. Electrified vehicles are one type of vehicle currently being developed for this purpose. In general, electrified vehicles differ from conventional motor vehicles because they are selectively driven by one or more battery powered electric machines. Conventional motor vehicles, by contrast, rely exclusively on the internal combustion engine to propel the vehicle.
[0003] A high voltage battery pack typically powers the electric machines and other electrical loads of the electrified vehicle. The battery pack includes a plurality of interconnected battery cells that store energy for powering these electrical loads. Numerous electronics modules are also housed inside the battery pack.
[0004] Moisture can accumulate inside the battery pack. Some internal components of the battery pack may therefore benefit from protection against moisture intrusion.
SUMMARY
[0005] A battery pack according to an exemplary aspect of the present disclosure includes, among other things, an electronics module and an electronics umbrella positioned to channel moisture away from the electronics module.
[0006] In a further non-limiting embodiment of the foregoing battery pack, the electronics module is a battery electronic control module.
[0007] In a further non-limiting embodiment of either of the foregoing battery packs, the electronics umbrella includes a base and a ramp extending from the base.
[0008] In a further non-limiting embodiment of any of the foregoing battery packs, the ramp is angled at a decline relative to the base.
[0009] In a further non-limiting embodiment of any of the foregoing battery packs, an enclosure houses the electronics module, the enclosure including a tray and a cover.
[0010] In a further non-limiting embodiment of any of the foregoing battery packs, the electronics module includes a connector cavity facing toward the cover.
[0011] In a further non-limiting embodiment of any of the foregoing battery packs, the electronics umbrella at least partially covers the connector cavity of the electronics module.
[0012] In a further non-limiting embodiment of any of the foregoing battery packs, a drain hole extends through the electronics umbrella.
[0013] In a further non-limiting embodiment of any of the foregoing battery packs, insulation is attached to the electronics umbrella.
[0014] In a further non-limiting embodiment of any of the foregoing battery packs, the insulation is attached to an inner surface of the electronics umbrella.
[0015] In a further non-limiting embodiment of any of the foregoing battery packs, the insulation is sandwiched between an enclosure wall and the electronics umbrella.
[0016] In a further non-limiting embodiment of any of the foregoing battery packs, the electronics umbrella is mounted to a wall of an enclosure that houses the electronics module.
[0017] A battery pack according to another exemplary aspect of the present disclosure includes, among other things, an enclosure, a battery assembly housed inside the enclosure, an electronics module mounted adjacent to the battery assembly and an electronics umbrella mounted to a wall of the enclosure. The enclosure is comprised of a first material having a first thermal conductivity and the electronics umbrella comprised of a second material having a second thermal conductivity that is less than the first thermal conductivity.
[0018] In a further non-limiting embodiment of the foregoing battery pack, the first material is a metal and the second material is a plastic.
[0019] In a further non-limiting embodiment of either of the foregoing battery packs, a stud protrudes from the wall, and the electronics umbrella is secured to the stud with a fastening device.
[0020] In a further non-limiting embodiment of any of the foregoing battery packs, the electronics umbrella includes a ramp configured to channel moisture away from the electronics module.
[0021] In a further non-limiting embodiment of any of the foregoing battery packs, the ramp extends at an angle relative to a base of the electronics umbrella.
[0022] In a further non-limiting embodiment of any of the foregoing battery packs, the electronics umbrella at least partially hovers over the electronics module and a second electronics module.
[0023] In a further non-limiting embodiment of any of the foregoing battery packs, the electronics module is mounted to the enclosure by a mounting flange.
[0024] A method according to another exemplary aspect of the present disclosure includes, among other things, positioning an electronics umbrella to at least partially extend above an electronics module housed inside a battery pack and communicating moisture that accumulates inside the battery pack along a surface of the electronics umbrella to a location remote from the electronics module.
[0025] The embodiments, examples and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible.
[0026] The various features and advantages of this disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 schematically illustrates a powertrain of an electrified vehicle.
[0028] FIG. 2 illustrates a battery pack of an electrified vehicle.
[0029] FIG. 3 illustrates portions of a battery pack.
[0030] FIG. 4 is a cross-sectional view through section A-A of FIG. 3 and illustrates a right hand orientation of an electronics umbrella.
[0031] FIG. 5 illustrates a left hand orientation of an electronics umbrella.
[0032] FIG. 6 illustrates yet another electronics umbrella.
[0033] FIG. 7 illustrates an exemplary mounting configuration of an electronics umbrella.
[0034] FIGS. 8A and 8B illustrate additional exemplary electronics umbrellas.
DETAILED DESCRIPTION
[0035] This disclosure details a battery pack of an electrified vehicle. The battery pack includes an electronics umbrella for preventing moisture, such as condensation, from infiltrating an electronics module housed inside the battery pack. In some embodiments, the electronics umbrella is arranged to channel moisture around and away from the electronics module. In other embodiments, the electronics module is comprised of a material having a thermal conductivity that is less than the thermal conductivity of the structure the electronics umbrella is mounted to. In this way, moisture accumulates on the structure before it accumulates on the electronics umbrella. These and other features are discussed in greater detail in the following paragraphs of this detailed description.
[0036] FIG. 1 schematically illustrates a powertrain 10 for an electrified vehicle 12 . Although depicted as a hybrid electric vehicle (HEV), it should be understood that the concepts described herein are not limited to HEV's and could extend to other electrified vehicles, including, but not limited to, plug-in hybrid electric vehicles (PHEV's), battery electric vehicles (BEV's) and fuel cell vehicles.
[0037] In one non-limiting embodiment, the powertrain 10 is a power-split powertrain system that employs a first drive system and a second drive system. The first drive system includes a combination of an engine 14 and a generator 18 (i.e., a first electric machine). The second drive system includes at least a motor 22 (i.e., a second electric machine), the generator 18 , and a battery pack 24 . In this example, the second drive system is considered an electric drive system of the powertrain 10 . The first and second drive systems generate torque to drive one or more sets of vehicle drive wheels 28 of the electrified vehicle 12 . Although a power-split configuration is depicted in FIG. 1 , this disclosure extends to any hybrid or electric vehicle including full hybrids, parallel hybrids, series hybrids, mild hybrids or micro hybrids.
[0038] The engine 14 , which in one embodiment is an internal combustion engine, and the generator 18 may be connected through a power transfer unit 30 , such as a planetary gear set. Of course, other types of power transfer units, including other gear sets and transmissions, may be used to connect the engine 14 to the generator 18 . In one non-limiting embodiment, the power transfer unit 30 is a planetary gear set that includes a ring gear 32 , a sun gear 34 , and a carrier assembly 36 .
[0039] The generator 18 can be driven by the engine 14 through the power transfer unit 30 to convert kinetic energy to electrical energy. The generator 18 can alternatively function as a motor to convert electrical energy into kinetic energy, thereby outputting torque to a shaft 38 connected to the power transfer unit 30 . Because the generator 18 is operatively connected to the engine 14 , the speed of the engine 14 can be controlled by the generator 18 .
[0040] The ring gear 32 of the power transfer unit 30 may be connected to a shaft 40 , which is connected to vehicle drive wheels 28 through a second power transfer unit 44 . The second power transfer unit 44 may include a gear set having a plurality of gears 46 . Other power transfer units may also be suitable. The gears 46 transfer torque from the engine 14 to a differential 48 to ultimately provide traction to the vehicle drive wheels 28 . The differential 48 may include a plurality of gears that enable the transfer of torque to the vehicle drive wheels 28 . In one embodiment, the second power transfer unit 44 is mechanically coupled to an axle 50 through the differential 48 to distribute torque to the vehicle drive wheels 28 .
[0041] The motor 22 can also be employed to drive the vehicle drive wheels 28 by outputting torque to a shaft 52 that is also connected to the second power transfer unit 44 . In one embodiment, the motor 22 and the generator 18 cooperate as part of a regenerative braking system in which both the motor 22 and the generator 18 can be employed as motors to output torque. For example, the motor 22 and the generator 18 can each output electrical power to the battery pack 24 .
[0042] The battery pack 24 is an exemplary electrified vehicle battery. The battery pack 24 may be a high voltage traction battery pack that includes a plurality of battery assemblies 25 (i.e., battery arrays or groupings of battery cells) capable of outputting electrical power to operate the motor 22 , the generator 18 and/or other electrical loads of the electrified vehicle 12 . Other types of energy storage devices and/or output devices could also be used to electrically power the electrified vehicle 12 .
[0043] In one non-limiting embodiment, the electrified vehicle 12 has two basic operating modes. The electrified vehicle 12 may operate in an Electric Vehicle (EV) mode where the motor 22 is used (generally without assistance from the engine 14 ) for vehicle propulsion, thereby depleting the battery pack 24 state of charge up to its maximum allowable discharging rate under certain driving patterns/cycles. The EV mode is an example of a charge depleting mode of operation for the electrified vehicle 12 . During EV mode, the state of charge of the battery pack 24 may increase in some circumstances, for example due to a period of regenerative braking. The engine 14 is generally OFF under a default EV mode but could be operated as necessary based on a vehicle system state or as permitted by the operator.
[0044] The electrified vehicle 12 may additionally operate in a Hybrid (HEV) mode in which the engine 14 and the motor 22 are both used for vehicle propulsion. The HEV mode is an example of a charge sustaining mode of operation for the electrified vehicle 12 . During the HEV mode, the electrified vehicle 12 may reduce the motor 22 propulsion usage in order to maintain the state of charge of the battery pack 24 at a constant or approximately constant level by increasing the engine 14 propulsion. The electrified vehicle 12 may be operated in other operating modes in addition to the EV and HEV modes within the scope of this disclosure.
[0045] FIG. 2 schematically illustrates a battery pack 24 that can be employed within an electrified vehicle. For example, the battery pack 24 could be part of the electrified vehicle 12 of FIG. 1 . The battery pack 24 includes a plurality of battery cells 56 that store electrical power for powering various electrical loads of the electrified vehicle 12 . Although a specific number of battery cells 56 are depicted in FIG. 2 , the battery pack 24 could employ a greater or fewer number of battery cells within the scope of this disclosure. In other words, this disclosure is not limited to the specific configuration shown in FIG. 2 .
[0046] The battery cells 56 are stacked side-by-side along a longitudinal axis A to construct groupings of battery cells 56 , sometimes referred to as cell stacks. The battery pack 24 can include one or more separate groupings of battery cells 56 .
[0047] In one non-limiting embodiment, the battery cells 56 are prismatic, lithium-ion cells. However, battery cells having other geometries (cylindrical, pouch, etc.), other chemistries (nickel-metal hydride, lead-acid, etc.), or both, could alternatively be utilized within the scope of this disclosure.
[0048] Spacers 54 , which can alternatively be referred to as separators or dividers, are optionally positioned between adjacent battery cells 56 of each grouping of battery cells 56 . The spacers 54 are made of thermally resistant and electrically isolating plastics and/or foams. The battery cells 56 , along with the spacers 54 and any other support structures (e.g., rails, walls, plates, etc.), may be collectively referred to as a battery assembly 25 . Two battery assemblies 25 are shown in FIG. 2 ; however, the battery pack 24 could include a greater or fewer number of battery assemblies within the scope of this disclosure.
[0049] An enclosure 60 generally surrounds each battery assembly 25 of the battery pack 24 . The enclosure 60 includes a plurality of walls 62 . The plurality of walls 62 together establish the enclosure 60 , which houses the various hardware and electronics of the battery pack 24 , including but not limited to, the battery assemblies 25 and at least one electronics module 58 . In one non-limiting embodiment, the electronics module 58 is a battery electronic control module (BECM). The electronics module 58 includes one or more connector cavities 72 for connecting various electrical components within the battery pack 24 .
[0050] The walls 62 of the enclosure 60 could be part of either a tray 64 or a cover 66 , in another non-limiting embodiment. The cover 66 is shown in phantom in FIG. 2 to better illustrate the interior components of the battery pack 24 . The cover 66 is attachable to the tray 64 to house the battery assemblies 25 and the electronics module 58 .
[0051] Referring now to FIGS. 3 and 4 , the electronics module 58 is mounted inside the enclosure 60 via a mounting flange 70 . The mounting flange 70 is secured to one of the walls 62 , which in the illustrated example is a bottom wall of the tray 64 . The electronics module 58 is mounted upright such that the connector cavities 72 are pointed upwardly toward the cover 66 of the enclosure 60 . In this upright pointed position, the connector cavities 72 of the electronics module 58 may be susceptible to moisture intrusion. An electronics umbrella 68 is therefore positioned inside the battery pack 24 . The electronics umbrella 68 is a hood-like structure arranged to cover the electronics module 58 . The electronics umbrella 68 channels moisture, such as condensation, away from the electronics module 58 to substantially prevent the moisture M from entering into the connector cavities 72 .
[0052] The exemplary electronics umbrella 68 includes a base 74 and a ramp 76 that extends from the base 74 . The size, shape and geometry of the electronics umbrella 68 , including the size, shape and geometry of each of the base 74 and ramp 76 , is not intended to limit this disclosure in any way. In one non-limiting embodiment, the ramp 76 extends at an angle α relative to the base 74 . The ramp 76 extends to a position in which it hovers above the electronics module 58 . The ramp 76 may be declined in a direction that extends from the cover 66 toward the tray 64 . In this way, the ramp 76 aids in communicating moisture around and away from the electronics module 58 . For example, moisture M that accumulates inside the enclosure 60 may drop onto the ramp 76 . As the moisture M accumulates, it is channeled down the ramp 76 , toward the base 74 , and away from the electronics module 68 . The moisture M may be channeled toward the bottom of the enclosure 60 , for example. The ramp 76 may include a drain hole 78 adapted to permit moisture M to pass through the ramp 76 after it has been channeled far enough away from electronics module 58 . In one non-limiting embodiment, the drain hole 78 is positioned near the interface between the ramp 76 and the base 74 . The drain hole 78 , however, could be positioned at other locations of the electronics umbrella 68 .
[0053] FIGS. 3 and 4 depict a right hand orientation of the electronics umbrella 68 . A left hand orientation of the electronics umbrella 68 may also be utilized to prevent moisture from entering the connector cavities 72 of the electronics module 58 (see, for example, FIG. 5 ). Other configurations of the electronics umbrella 68 are also contemplated as within the scope of this disclosure. In yet another non-limiting embodiment, the electronics umbrella 68 is arranged to cover a plurality of electronics modules 58 (see, for example, FIG. 6 ). In addition, although a single electronics umbrella 68 is depicted in the schematics accompanying this disclosure, the battery pack 24 could be equipped with multiple electronics umbrellas 68 .
[0054] The electronics umbrella 68 is mounted to at least one of the walls 62 of the enclosure 60 . In this embodiment, the wall 62 is a sidewall of the enclosure 60 , and could be a sidewall of the tray 64 . However, it should be understood that the electronics umbrella 68 could be mounted to any portion of the enclosure 60 , including any wall 62 or any portion of the tray 64 or the cover 66 .
[0055] In one non-limiting embodiment, the electronics umbrella 68 is a plastic structure and the walls 62 of the enclosure 60 are metallic structures. In another non-limiting embodiment, the electronics umbrella 68 is made of a material having a first thermal conductivity and the walls 62 of the enclosure 60 are made of another material having a second thermal conductivity. The first thermal conductivity may be a lower thermal conductivity than the second thermal conductivity to ensure that the moisture M (e.g., condensation) accumulates on the enclosure 60 prior to the electronics umbrella 68 .
[0056] A non-limiting mounting configuration of the electronics umbrella 68 is illustrated in FIG. 7 . One or more studs 80 protrude from the wall 62 of the enclosure 60 . The stud 80 extends through a slot 82 formed in the base 74 of the electronics umbrella 68 . The electronics umbrella 68 is secured to the wall 62 using a fastening device 84 , such as a nut. In another non-limiting embodiment, the electronics umbrella 68 is glued to one of the walls 62 of the enclosure 60 . Additional attachment mechanisms are also contemplated within the scope of this disclosure. Moreover, the electronics umbrella 68 could be mounted to the enclosure 60 or any other neighboring structure within the enclosure 60 .
[0057] Referring to FIGS. 8A and 8B , insulation 86 can be optionally used in conjunction with the electronics umbrella 68 . The insulation 86 reduces the amount of heat transfer that is effectuated between the wall 62 of the enclosure 60 and the electronics umbrella 68 . In a first non-limiting embodiment, the insulation 86 is attached to an inner surface 88 of the electronics umbrella 68 (see FIG. 8A ). In a second non-limiting embodiment, the insulation 86 is sandwiched between the base 74 of electronics umbrella 68 and the wall 62 the electronics umbrella 68 is mounted to (see FIG. 8B ). However, the insulation 86 could be positioned at any location that has an influence on the amount of heat transfer permitted to occur between the electronics umbrella 68 and the enclosure 60 .
[0058] Although the different non-limiting embodiments are illustrated as having specific components or steps, the embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments.
[0059] It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should be understood that although a particular component arrangement is disclosed and illustrated in these exemplary embodiments, other arrangements could also benefit from the teachings of this disclosure.
[0060] The foregoing description shall be interpreted as illustrative and not in any limiting sense. A worker of ordinary skill in the art would understand that certain modifications could come within the scope of this disclosure. For these reasons, the following claims should be studied to determine the true scope and content of this disclosure.
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A battery pack according to an exemplary aspect of the present disclosure includes, among other things, an electronics module and an electronics umbrella positioned to channel moisture away from the electronics module.
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FIELD OF THE INVENTION
The present invention generally relates to machinery and systems for tufting carpets. In particular, the present invention relates to an improved puller roll assembly for a tufting machine.
BACKGROUND OF THE INVENTION
In addition to yarn feed systems and/or pattern yarn feed attachments, tufting machines generally include pairs of toothed puller rolls that tension yarns from the yarn feed mechanism or attachments to needles of the tufting machines. Such puller roll systems typically consist of a drive roll and an idler roll that operate in a rotating, intermeshing relationship. As the rolls rotate, the yarns are engaged and pinched between the teeth of the puller rolls, which engage in an intermeshing fashion, defining a yarn pinch area between the rolls. The yarns are engaged and pinched between the teeth of the puller rolls as they pass through the pinch area, such that the rotation of the rolls causes the yarns to be tensioned between the rolls for feeding to the needles.
With such traditional puller roll systems as described above, there generally is only a limited area or point of contact at which the yarns are pinched and pulled between the puller rolls. As a result of such limited contact of the yarns with the rolls, the yarns therefore must be tightly engaged or pinched between the teeth of the rolls to try to limit slippage and to thus provide consistent tensioning and feeding of the yarns through the system. As a result, the spacing and intermeshing of the rolls is critical for achieving a uniform, substantially constant flow of the yarns through the rolls without significant slippage or misfeeding of the yarns. As a consequence, it generally has been necessary to monitor and make frequent adjustments to the positions and spacings between the rolls to compensate for the feeding of different sizes or thicknesses of yarns. Such adjustments typically are made manually through the use of adjustment shims, which manual adjustments often are not sufficiently precise, and thus can necessitate additional adjustments. Furthermore, the pinching of the yarns by the rolls can damage or cause breaking of the yarns if the spacing or pinching is too tight or can cause jamming of the rolls if knots are passed therebetween, resulting in misfeeding of the yarns.
There is, therefore, a need for an improved puller roll system that can securely and consistently tension yarns of various sizes to the needles of a tufting machine without requiring continuous adjustment of the puller rolls.
SUMMARY OF THE INVENTION
Briefly described, the present invention relates to an improved puller roll system for feeding yarns to the needles of a tufting machine. According to one embodiment of the invention, the puller roll system includes at least one driven puller roll and a pair of floating puller rolls. The driven and floating puller rolls each include radially projecting teeth, and the floating puller rolls are mounted in an intermeshing relationship with the driven puller roll so that the floating puller rolls are rotated with the rotation of the driven puller roll. A yarn engagement path is defined between the driven puller roll and the floating puller rolls along which the yams are received and are passed in a winding, substantially serpentine path. The puller rolls engage the yarns along the engagement path at multiple points or areas of contact with the yarns being engaged between both of the floating puller rolls and the driven puller roll and with the yams being wrapped about a portion or wrap area of the driven puller roll.
As a result, the amount and/or area of contact between the yarns and the puller rolls is substantially increased so that the yarns can be securely tensioned through the engagement path towards the needles without requiring the yarns to be pinched tightly between the puller rolls. In addition, due to the increased areas and amount of contact along which the puller rolls engage the yams, the puller roll system of the present invention can be used to tension various types and sizes of yarns without requiring frequent adjustments of the positions of or spacings between the puller rolls. Consequently, the puller roll system of the present invention enables looser spacing between the puller rolls, with the spacings being set at a distance sufficient to enable a minimum engagement and contact between the yarns and the teeth of the puller rolls sufficient to tension the yarns without the yarns necessarily being tightly pinched between the rolls, which reduces the likelihood that the yarns will be damaged by the puller rolls.
Various object features and advantages of the present invention will become apparent to those of skill in the art upon reading the following detailed description in view of the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view schematically illustrating a tufting machine including a puller roll system according to one embodiment of the present invention.
FIG. 2 shows a cut-away, back side view of the puller roll system of the present invention.
FIG. 3 is an end view, with portions removed, of the puller roll system of FIG. 1 .
FIG. 4 shows a cross-sectional view of the puller roll system of the present invention taken along section A—A of FIG. 2 .
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings in which like numerals indicate like parts throughout the several views, FIG. 1 discloses a tufting machine 10 including a frame 11 and a reciprocable needle bar 12 supporting a plurality of spaced needles 13 disposed therealong. The needles 13 are reciprocated vertically through a backing fabric or material 14 , as the backing fabric 14 is moved through the machine 10 in a direction of feed indicated by arrow F. Each of the needles carries a yarn 16 and cooperates with a corresponding looper 17 so as to form a series of loops or tufts of yarn in the backing fabric 14 as each needle penetrates the backing fabric, as indicated in FIG. 1 . The tufting machine 10 further includes a yarn feed mechanism 20 that is mounted on and supported by the tufting machine frame and includes a series of yarn feed rolls 21 , 22 that feed the yarns 16 at prescribed or programmed rates of feed in accordance with programmed pattern instructions to the puller roll assembly 25 of the present invention for the feeding of the yarns 16 to the individual needles 13 to form or tuft desired patterns in the backing fabric passing beneath the needles 13 .
It will be understood that the yarn feed mechanism 20 can include any type of known pattern yarn feed mechanisms, including computer controlled, motor driven yarn feed rolls or other conventional yarn feed/drive mechanisms including roll and scroll type pattern attachments that control the feeding of all the yarns across the width of the tufting machine to their respective needles. Other known types of yarn feed mechanisms that can be used include multiple feed rolls for controlling the feeding of specific sets or repeats of yarns to selected needles, and further including the use of individual yarn feed rolls for controlling the feeding of individual yarns to a respective needle. For example, U.S. Pat. Nos. 6,009,818 and 5,983,815 disclose pattern yarn feed devices for controlling the feeding and distribution of the yams, and U.S. Pat. No. 5,979,344 discloses a precision drive system for driving various operative elements of the tufting machine, which systems can be used with the present invention and are incorporated herein by reference.
As shown in FIG. 1, the puller roll assembly 25 of the present invention is mounted to the tufting machine frame 11 between the yarn feed mechanism and the needles and receives and pulls the yarns 16 from the yarn feed mechanism 20 and feeds the yarns 16 to needles 13 . The puller roll assembly 25 (FIG. 2) generally includes a pair of spaced bearings or mounting brackets 26 and 27 that are mounted to the tufting machine frame as conventionally known. The mounting brackets or bearings generally are substantially “U” or “C” shaped brackets or plates, typically formed from a metal or other similar material. Each mounting bracket or bearing generally includes a forward or proximal bearing member or portion 28 that is mounted to the tufting machine frame by a series of spaced machine mounts 29 (FIGS. 3 and 4 ), such as bolts, screws or other similar kinds of fasteners, and a rearward, distal bearing member or portion 31 that generally is adjustably mounted with respect to its forward bearing member 28 , in a position spaced from the forward, proximal bearing member or portion.
As indicated in FIG. 3, the distal bearing member 31 of each bearing or mounting bracket is adjustably mounted to its proximal bearing member 28 by fasteners, shown in dashed lines 32 , such as bolts, screws, pins or other similar kinds of fasteners or adjustable mounting mechanisms. The fasteners 32 generally each include a head 33 that typically is countersunk into the distal bearing members 31 and a shank portion that extends through its distal bearing member 31 and is received in and engages a corresponding recess or aperture 36 formed in the proximal bearing member 28 therefor.
As indicated in FIGS. 2-4, the mounting brackets 26 and 27 rotatably support a series of intermeshing puller rolls 40 , 41 , and 42 at each end thereof. Each of the puller rolls 40 - 42 generally is an elongated roll or gear having a series of radialy projecting teeth 40 A, 41 A, and 42 A, respectively, which teeth intermesh and engage the yarns 16 (FIG. 4) therebetween as the rolls are rotated. A first one of the puller rolls 40 generally is mounted to the proximal bearing members 28 of the mounting brackets 26 and 27 and is a power driven puller roll, generally driven by a motor, such as indicated by 43 in FIG. 1, in a known or conventional manner. The remaining or second and third puller rolls 41 and 42 (FIGS. 3 and 4) generally are idler or floating puller rolls, each rotatably mounted at their ends to the distal bearing members 31 of mounting brackets 26 and 27 (FIG. 2 ). The floating puller rolls 41 and 42 generally are rotated with the rotation of the drive roll 40 , as the teeth 41 A and 42 A of puller rolls 41 and 42 are engaged and intermesh with the teeth 40 A of the driven puller roll 40 . This engagement between the teeth of the floating puller roll and the driven puller roll creates or defines multiple areas of contact 44 and 46 between the teeth of puller rolls 40 and 41 , and between puller rolls 40 and 42 , respectively.
As illustrated in FIGS. 3 and 4, a yarn engagement path 47 is defined between the rolls and extends from an upper end or entrance 48 of the puller roll assembly 25 to a lower end or exit 49 from which the yarns 16 are passed for feeding to their respective needles in the direction of arrows 50 (FIG. 4 ). As the yarns are passed along the yarn path 47 , they are engaged between the teeth 40 A and 41 A of puller rolls 40 and 41 at a first area of contact 44 , and are further engaged between the intermeshing teeth 40 A and 42 A of puller rolls 40 and 42 at a second area of contact 46 to provide multiple points of engagement and gripping between the teeth of the puller rolls and the yams. In addition, between the areas of contact 44 and 46 , the yarns 16 wrap at least partially around the driven puller roll 40 along a wrap area or region 51 defined along a portion of the circumference or periphery of the driven puller roll 40 , between the areas of contact 44 and 46 , providing still further engagement of the yarns with the driven puller roll. This increased or enhanced engagement of the yarns at multiple points or areas of contact between the teeth of the driven and floating puller rolls 40 and 41 and 42 , respectively, as well as the further engagement of the yarns by the teeth 40 A of driven puller roll 40 at the wrap area 51 along the driven puller roll 40 provides an enhanced positive gripping of the yarns and minimizes risk of slippage of the yarns as it is pulled through or along its yarn engagement path 47 between the puller rolls 40 , 41 , and 42 .
The floating puller rolls generally are positioned in substantially parallel and vertically spaced, aligned positions, each oriented at an angle with respect to the driven puller roll such that the central axis 52 and 53 of each floating puller roll is laterally offset from the central axis 54 of the driven puller roll 40 as shown in FIGS. 3 and 4. As a result, the multiple areas of contact 44 and 46 are provided at spaced locations with the wrap area 51 defined therebetween, and with the yarn path generally extending along a curved path about the drive roll so that the yarns are moved along a somewhat serpentine path through the puller rolls. The positions of the floating puller rolls 41 and 42 with respect to the driven puller roll 40 generally are adjustable by the adjustment or movement of the distal bearing members 31 with respect to their associated proximal bearing members 28 of the mounting brackets 26 and 27 in order to adjust or set the spacing and thus the amount of engagement between the teeth of the puller rolls as needed for feeding a desired range of thicknesses or sizes of yams. Additionally as indicated in FIGS. 3 and 4, shims 56 can further be placed within the gaps 57 between the proximal and distal bearing members 28 and 31 as desired to help secure or fix the spacing of the proximal or distal bearing members and thus the spacing of the driven and floating 40 and 41 and 40 and 42 puller rolls with respect to one another.
With the present invention, the floating puller rolls 41 and 42 do not have to be mounted in a tight, pinching engagement with the drive roll 40 so that the yarns 16 (FIG. 4) are tightly engaged and pinched between the teeth of the floating and drive puller rolls avoid slippage and to ensure positive engagement of the yarns by the puller roll assembly of the present invention. Instead, with the puller roll assembly of the present invention, by providing multiple points or areas of contact and an additional at least partial wrapping of the yarns about the periphery of the driven puller roll 40 , the spacings between the puller rolls can be much looser, typically being set at a minimum engagement or spacing so as to enable relatively loose or light contact or engagement of the yarns therebetween with the potential for slippage of the yarns minimized, instead of requiring a very tight, pinching engagement of the yarns between the teeth of the puller rolls as generally is necessary in conventional puller roll assemblies.
As a result, with the puller roll assembly of the present invention, the floating and drive puller rolls are spaced sufficiently to maintain a minimum amount of contact between the yams and the intermeshing teeth of the puller rolls, which spacing is sufficient to provide a positive engagement and pulling of the yarns with the risks of slipping being minimized, but without the yarns further having to be tightly engaged and pinched between the puller roll teeth. In addition, by providing multiple areas or zones of contact 44 and 46 , and a wrap area 51 along which the yarns are engaged by the teeth of the drive roll 40 , the floating puller rolls of the present invention generally do not need to be continually adjusted with respect to the drive roll 40 , and, can accommodate the feeding of a variety or range of different size thickness yarns and the passage of knots or other imperfections or obstructions in the yarns passing therethrough without the yarns becoming jammed and/or requiring frequent, precise mechanical adjustment of the positions of the floating puller rolls with respect to the driven puller roll 40 .
In the operation of the puller roll assembly 25 of the present invention, a series of yarns 16 (FIG. 1) are fed from the yarn feed mechanism 20 into the upper end 48 (FIG. 4) of the puller roll assembly 25 . The yarns 16 are passed along a yarn path 47 between driven puller roll 40 and floating puller rolls 41 and 42 . The yarns are engaged between the intermeshing teeth 40 A and 41 A of the driven and floating puller rolls 40 and 41 , respectively, at a first area of contact 44 , then are extended or wrapped about a wrap zone or area 51 extending at least partially about the periphery of drive roll 50 , and further are engaged along a second area of contact 46 between the teeth 40 A and 42 A of driven puller roll 40 and floating puller roll 42 , respectively. The intermeshing teeth of the drive and floating puller rolls at the areas or points of contact 44 and 46 tend to lightly engage and pull the yarns at multiple points of contact. In addition, the friction between the yarns and teeth 40 A of driven puller roll 40 along the wrap area 51 , in conjunction with the engagement of the yarns at the areas of contact 44 and 46 , helps the yarns to be pulled along the yarn path 47 through the puller roll assembly 25 without requiring a tight pinching engagement of the yarns by the teeth of the puller rolls. The yarns exit the puller roll assembly at the lower end 49 thereof, and are fed to individual needles 13 (FIG. 1) at a prescribed rate of feed for insertion into the backing fabric 14 passing through the tufting machine.
The present invention thus provides a cost effective and reliable puller roll assembly for feeding the yarns to the needles of a tufting machine, which does not require a tight, pinching contact between the teeth of the rolls and yarns to avoid potential slippage of the yarns, and further permits or accommodates the feeding of various size or thickness of yarns without requiring continual or frequent adjustments of the spacing of the puller rolls for effectively and consistently feeding the yarns to the respective needles. It will be understood by those skilled in the art that while the foregoing invention has been disclosed with reference to preferred embodiments or features, various modifications, changes and additions can be made to the foregoing invention without departing from the spirit and scope of the invention as set forth in the following claims.
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A puller roller system for tufting machines having a series of intermeshed puller rolls for tensioning a series of yarns to one or more needles of the tufting machine. According to one embodiment of the invention, the puller roller system includes at least one toothed, driven puller roll in rotating and intermeshing relationship with at least two toothed, floating puller rolls. The spacing between the puller rolls is sufficient to securely engage and tension the yarns to the needles without pinching the yarn.
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This application is a division of application Ser. No. 08/104,472, filed Jul. 28, 1993.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an electronic substrate processing system in a clean room, and its equipments.
2. Prior Art
Electronic substrates such as semiconductor wafers are manufactured in a clean room, the atmosphere in which has been cleaned. The manufacture is increased in yield by increasing the cleanliness of the atmosphere.
On the other hand, recently semiconductor integrated circuits have been increased in the degree of integration. In association with this increase, a so-called "local clean system" has been employed in which electronic substrates such as semiconductor wafers are set in a portable closed container when conveyed. For instance in a processing step in which a thin film forming deposition system (CVD, PVD or the like) is carried out for wafers, the degree of growth of a native oxide film on the wafers, or the contamination of the wafers by metal ions contained in the air cannot be neglected; that is, the exposure of the wafers in the air cannot be neglected in manufacture of the wafers.
Prior to the thin film deposition system, the wafer is cleaned with a cleaning equipment. This wafer cleaning operation should be carried out with the thin film deposition system taken into account because the thin film deposition system takes a relatively long period of time, several tens of minutes to several hours, for the following reasons: A native oxide film grows on the cleaned wafer quickly; that is, the cleaned wafer is liable to be contaminated by the ions in the air. Therefore, if, in the thin film deposition system, wafers to be processed next are exposed in the internal atmosphere, then a native oxide film grows on them (the percentage of growth of the native oxide film being increased abruptly in about one hour exposure), and they are progressively contaminated by the metal ions.
Sometimes the cleaning operation by the cleaning equipment takes several tens of minutes. Hence, in the conventional processing system, the processing operation is less in the degree of freedom, and therefore it is difficult to increase the productivity.
SUMMARY OF THE INVENTION
In view of the forgoing the problem, an object of this invention is to eliminate the above-described difficulties accompanying a conventional electronic substrate processing system. More specifically, an object of the invention is to provide an electronic substrate processing system using a portable closed container, and its equipments in which, with the time limitation in operation between the equipments eliminated, the processing operation is increased in the degree of freedom, and the productivity is increased as much.
According to first aspect of the present invention, an electronic substrate processing system comprises a processing equipment for processing electronic substrates including semiconductor wafers and liquid crystal substrates; a cleaning equipment for cleaning said electronic substrate in a predetermined processing step; a portable closed container for accommodating a cassette containing said electronic substrate; a purging station for gas-purging said portable closed containers; and a storage member for storing said portable closed containers, wherein said cassette accommodates said electronic substrates which have been cleaned by said cleaning equipment being set in said portable closed container and purged with an inert gas in said purging station, and said portable closed container or containers is stored in said storing section when necessary.
According to second aspect of the present invention, a purging station comprises an independent casing having a container carry-in/carry-out opening; a purging unit provided in said casing, said purging unit having a container stand; a portable closed container including a container body and a bottom lid for storing and conveying and a cassette which accommodates electronic substrates, said cassette being placed on said container stand; a container body lifting unit for lifting said container body; purging pipes first ends of which are opened in said purging unit; and a purging control unit for controlling said purge station, wherein said purging unit incorporates a purging mechanism which operates to open and close the bottom lid of said container on said container stand to selectively communicate the inside of said container with the inside of said purging unit.
According to third aspect of the present invention, a purging station comprises an independent casing having a container or cassette carry-in/carry-out window; a container stand provided in said casing; a portable closed container including a container body and a bottom lid for storing and conveying and a cassette which accommodates electronic substrates, said cassette being placed on said container stand; a container lid opening and closing mechanism for opening said bottom lid; purging pipes first ends of which are opened in said casing; and a purging control unit for controlling said purging station.
A fourth aspect of the present invention, a purging station comprises a purging chamber provided in a purging unit having an opening, a periphery of said purging unit serving a container stand on which a portable closed container is set; purging pipes, first ends of which are opened in said purge chamber; a purging control unit for controlling said purge unit; and a purging mechanism for opening and closing said bottom lid of said container on said container stand to selectively communicate an inside of said container with an inside of said purging chamber, wherein said purging chamber is defined in said purging unit, which includes an independent casing, by a skirt which is provided in such a manner said skirt gas-tightly covers said opening of said purging unit from inside, and said casing having a cassette carry-in/carry-out window.
According to fifth aspect of the present invention, an electronic substrate cleaning equipment comprises a cleaning equipment for cleaning substrates for electronic equipment which are set in a cassette being carried thereinto through a cassette carry-in opening of a casing thereof, said cassette being carried by a portable closed container, said substrates being cleaned in a predetermined cleaning step; purging means for purging said portable closed container with a gas which is inactive with said substrates accommodated in a portable closed container, said purging means mounted in said casing; and means for setting in a portable closed container said cassette which has been finally processed in said cleaning step, wherein said casing has a carry-in/carry-out opening for said portable closed container.
According to sixth aspect of the present invention, a gas-purging equipment comprises a portable closed container for accommodating and conveying electronic substrates; a gas purging unit for evacuating and subsequently purging said portable closed container with a gas which is inactive with said electronic substrates, said gas-purging unit being connected through pipes to a vacuum source and an inert gas source, and said gas-purging unit being divided with a wall to form a gas-purging unit body and a container accommodating section, said wall having a through-hole through which said gas purging unit body section and said container accommodating section are communicated with each other, wherein after said portable closed container is set on said wall, said bottom lid of said container is opened so as to communicate said inside of said container with said inside of said gas-purging unit body whereby said inside of said portable closed container is evacuated and purged with one of an insert gas and a heated inert gas.
In the system of the invention, the cassette is set in the closed container when moved between the equipments. Therefore, the electronic substrates are never exposed in the atmosphere in the clean room. Furthermore, the cassette is stored in the closed container which has been gas-purged. The container can be gas-purged at the purging station when necessary. The time limitation in operation between the equipments is eliminated, and the processing operation is increased in the degree of freedom.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view showing the layout of an electronic substrate processing system, which constitute one embodiment of this invention;
FIG. 2 is an explanatory diagram showing a first example of a purging station in the system of the invention;
FIG. 3 is an explanatory diagram showing a closed container and a first example of a purging unit in the system of the invention;
FIG. 4 is an explanatory diagram showing a second example of the purging unit;
FIG. 5 is an explanatory diagram showing a third example of the purging unit;
FIG. 6 is an explanatory diagram showing a fourth example of the purging unit;
FIG. 7 is an explanatory diagram for a description of the structure of a locking/unlocking mechanism in the closed container;
FIG. 8 is an explanatory diagram showing a second example of the purging station;
FIG. 9 is an explanatory diagram showing a third example of the purging station;
FIG. 10 is an explanatory diagram showing a fourth example of the purging station;
FIG. 11 is an explanatory diagram showing a fifth example of the purging station;
FIG. 12 is an explanatory diagram showing a first example of a cleaning equipment having a purging function;
FIG. 13 is an explanatory diagram showing a second example of the cleaning equipment;
FIG. 14 is an explanatory diagram showing a third example of the cleaning equipment;
FIG. 15 is an explanatory diagram showing a fourth example of the cleaning equipment;
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
One preferred embodiment of this invention will be described with reference to the accompanying drawings.
In FIG. 1, reference numeral 100 designates a film forming deposition system arranged in a clean room; 200, a wafer cleaning device; 300, a purging Station; 400, a clean stocker; 500, a transfer robot on which a product placing device is mounted; and 30, a portable closed container.
FIG. 2 shows one example of the purging station.
In FIG. 2, reference numeral 1 designates a parallelopiped casing having a window in its front wall 1A; 3, a first example of a purging unit. The purging unit 3, as shown in FIG. 3, has a closed box 20 in which a container opening and closing mechanism is provided to selectively communicate the inside of the closed box 20 with the inside of the portable closed container 30. Reference numeral 4 designates a gas supplying pipe. One end portion 4A of the pipe 4 is extended outside the casing 1, and the other end portion 4B is opened in the closed box 20. The pipe 4 has an electromagnetic control valve 5 at the middle. Reference numeral 6 designates a gas discharging pipe. One end portion 6A of the pipe 6 is extended outside the casing 1, and the other end portion 6B is opened in the closed box 20. The pipe 6 has an electromagnetic control valve 7 at the middle. Further in FIG. 2, reference numeral 9 denotes a high performance filter; and 10, a purging unit controller which controls the operations of the electromagnetic control valves 5 and 7 and the operation of the above-described container opening and closing mechanism. Reference numeral 60 designates a container lifting unit for lifting a container body 31 (shown in FIG. 7). In the embodiment, the container lifting unit is of cylinder-operated type. The;one end portion 4A of the gas supplying pipe 4 is connected to an inert gas source. The one end portion 6A of the gas discharging pipe 6 is connected to an exhaust pipe or the like which is laid under the floor of the clean room.
Fans with filters (not shown) may be installed on the ceiling and the rear wall of the casing 1, to cause the clean air to flow upwardly and to flow from the rear side of the casing to the front side at all times. This is effective in eliminating the difficulty that, in placing a wafer cassette 70 in the container 31 inside the casing 1, dust in the atmosphere in the casing 1 sticks on the surfaces of the wafers W.
FIG. 3 shows the first example of the purging unit 3 in more detail.
In FIG. 3, reference numeral 21 designates a lifting unit; 22, a rod; and 23, a lifting stand. The lifting stand 23 includes a flange 23A which is larger in diameter than the opening 20A of the closed box 20. Normally, the lifting stand 23 is held fitted in the opening 20A in such a manner that the flange 23A pushes against the lower periphery of the opening 20A with a gap between the side wall of the lifting stand 23 and the opening 20A.
The body 31 of the portable closed container 30 has an opening 33 which is surrounded by a flange 32. Further in FIG. 3, reference numerals 34 and 35denote seal materials; 36, a handle, and 40, the bottom lid of the closed container.
FIG. 4 is a second example of the purging unit 3.
In the purging unit, a gas supplying pipe 4B and a gas discharging pipe 6B are opened in the closed box 20 in the vicinity of the opening 20A. The lifting stand 23 is moved vertically through an arm 25 by a ball screw 26, which is provided in the closed box 20 near one side. Those openings are covered with an elastic skirt of bellows-type 29, and isolated from the drive section of the lifting stand 23. Further in FIG. 4, reference numeral 27 designates an electric motor; and 28, a guide.
In the purging unit, the inert gas is jetted into the opening 20A, and it is caused to flow into the container when the lifting stand 23 is slightly lowered. In the purging unit, the inert gas is not filled in the whole of the closed box 20, which results in the economical use of the inert gas.
FIG. 5 shows a third example of the purging unit.
Prior to the gas-purging of the container, it is necessary to evacuate the latter. In this evacuation of the container, the difference between the pressures inside and outside the container body cannot be neglected depending on the material of the container body. In order to solve this problem, in the third example of the purging unit, a container accommodating chamber for covering the container is provided. The container accommodating chamber is evacuated at the same time the container is evacuated.
In FIG. 5, reference character 80B designates a wall defining the container accommodating chamber B which is closed with a lid 83. The container accommodating chamber B is communicated with a purging chamber A through through-holes 81. Therefore, in evacuation and in gas-purging, the purging chamber A, the container accommodating chamber B, and the container body are communicated with one another; that is, the insides of them are equal in pressure. In FIG. 5, reference numeral 82 designates filters engaged with the through-holes 81.
FIG. 6 shows a fourth example of the purging unit.
In the purging unit shown in FIG. 6, its container accommodating chamber is formed by a semi-spherical cover 84. The cover 84 is semi-spherical, and therefore it can be relatively small in wall thickness with its mechanical strength maintained high. And for the same reason, it can be miniaturized.
In each of the above-described examples of the purging unit, the bottom lid 40 of the closed container is hollow, and has a lock mechanism as shown, for instance, in FIG. 7. In FIG. 7, reference numeral 44 designates a cam; 45, a plate-shaped lock arm having a rolling element 45a, the lock arm 45 being cantilevered in such a manner that it is movable and tiltable longitudinally; 46, fulcrum members; and 47, a spring. A cam shaft 48 is extended from the center of the upper wall of the lifting stand 23 into the bottom lid 40, and it is spline-engaged with the cam 44 when the bottom lid 40 is coaxially set on the lifting stand 23. The lifting stand 23 incorporates a cam shaft driving mechanism 49 for turning the cam shaft 48 through a predetermined angle. The cam shaft driving mechanism 49 and the cam shaft 48 form a locking/unlocking mechanism. The lock arm 45 is engaged with a recess 33A, which is formed in the inner surface of the flange 32 defining the opening 33 of the container body 31.
Next, in this configuration, the wafer cassette containing the wafers is transferred to the stand provided with the carry-in opening 200A of the wafer cleaning device 200 and transferred to the thin film deposition system 100.
The wafer cassette is handled as follows:
(1) The wafer cleaning device 200 has a plurality of chemical solution tanks, pure water tanks, and a drying section in its casing. Those tanks are arranged in a predetermined order. In the device 200, the wafer cassette is dipped in the above-described tanks in a predetermined order and dried at the drying section, and the wafer cassette thus dried is set on the stand at the carry-out opening 200B.
(2) When the wafer cassette thus cleaned is set on the stand at the carry-out opening 200B, the transfer robot 500 moves to the carry-out opening 200B, and inserts the wafer cassette into the purging station 300 through the window 2, and sets it on the bottom lid 40 of the container 30 which is set on a portion of the upper wall of the closed box 20 (hereinafter referred to as "a stand portion 20B", when applicable). In this operation, the container body 31 has been raised to a predetermined height with its handle 36 held by a holder 62 provided at the end of the rod 61 of the container body lifting unit 60.
(3) When a sensor (not shown) detects that the wafer cassette has been set on the bottom lid, the rod 61 of the container body lifting unit 60 is moved downwardly to set the container body 31 on the stand portion 20B (FIG. 2) of the purging unit in such a manner that the container body 31 is pushed against the stand portion 20B, so that the inside of the container body 31 is gas-tightly isolated from the outside.
(4) Under this condition, the electromagnetic control valves 5 and 7 are opened, so that the inert gas (N 2 gas in the embodiment) is jetted from the one end portion 4B of the gas supplying pipe 4 into the closed box 20, while the air in the latter 20 is discharged outside the casing 1 through the gas discharging pipe 6; that is,! the air in the closed box 20 is replaced by the inert gas.
(5) After a predetermined period of time, the lifting stand 23 is slightly lowered, so that the bottom lid 40 is disengaged from the container body opening 33; that is, the inside of the container body 31 is communicated with the inside of the closed box 20, so that the air in the container body 31 is replaced by the inert gas.
(6) In a predetermined period of time, the lifting stand is raised to the original position, and the above-described locking/unlocking mechanism (FIG. 7) operates. That is, the lock arm 45 is engaged with the recess 33A, so that the bottom lid 40 is gas-tightly engaged with the container body opening 33, and the electromagnetic control valves 5 and 7 are closed.
(7) Thereafter, the rod 61 of the container body lifting unit 60 is moved upwardly, and the arm handling robot 500A of the movable robot 500 operates to place the container 30 on the latter 500.
(8) The transfer robot 500 carries the container 30 thus purged over to the apron 400A of the clean stocker 400. Thereupon, the container handling robot 400B in the clean stocker 400 operates to move the container 30 from the apron 400A to a shelf 400C and set it on the latter 400C.
(9) Of a plurality of containers stored in the clean stocker 400, the specified one is delivered from the shelf to the tranfer robot 500 by the container handling robot 400B.
(10) The transfer robot 500 delivers the container 30 to an container interface 101 which is the carry-in and carry-out opening of the film forming deposition system 100.
(11) In the film forming deposition system 100, the wafer cassette 70 is taken out of the container 30 brought through the container interface 101, and it is delivered to a CVD oven (not shown) and so forth; that is, a thin film deposition system is carried out.
In the embodiment, the wafer cassette 70, which has been cleaned and dried in the cleaning equipment 200, is delivered to the purging station 300, where it is set in the container 30 and purged with an inert gas which is inactive with the wafers. Thus, the wafers are held in the container 30 filled with the inert gas. The wafers are exposed in the air when conveyed from the cleaning equipment 200 to the purge station 300; however, native oxide films scarcely grow on them, because the period of time for which they are exposed in the air during the conveyance is extremely short.
In the embodiment, the wafer cassette 70 set in the container is stored in the clean stocker 400. Hence, the time limitation in operation between the equipments is eliminated; that is, the troublesome requirement is eliminated that, in order to reduce the waste time of holding the cleaned wafer cassette, the cleaning operation must be performed in association with the operation of the film forming deposition system 100. In the case where the film forming deposition system has no container interface, in the clean stocker 400 the wafers are taken out of the wafer cassette 70 and delivered to the transfer robot 500. And the wafers are conveyed to the film forming deposition system 100 while being exposed in the air. In this operation, it is necessary to reduce the time of conveyance as much as possible, thereby to minimize the growth of native oxide films on the wafers.
FIG. 8 shows a second example of the purging station which is provided for an upper lid type portable closed container 600.
In FIG. 8, reference numeral 601 designates a container body; 602, an upper lid; 603, a handle; 604, a lid operating (opening and closing) mechanism; 605, a stand on which the container 600 is set; and 606, a purging chamber.
FIGS. 9 and 10 show third and fourth examples of the purging stations. In those purging stations, the casing 1 has a container storing section 1C, and accommodates a container handling robot 80. The container body 31 has handles 31A on its side wall.
In each of the purging stations shown in FIGS. 9 and 10, the container handling robot 80 operates to convey the container 30 between the purge unit 3 and a plurality of shelves 1D. The container handling robot 80 comprises: a hand 80A with fingers 80a; and an arm 80B adapted to turn and lift the hand 80A. The fingers 80a are engaged with the handles 31A of the container body 31.
In each of the purging stations shown in FIGS. 9 and 10, a plurality of empty containers are stored in the container storing section 1C. Therefore, when any one of the shelves 1D is specified, the empty container on the shelf 1D thus specified can be automatically set on the stand of the purging unit 3 by the container handling robot 80. That is, the purging stations are free from the troublesome operation that an empty container must be taken into the purging station from outside for every gas-purging operation.
The fourth example of the purge station shown in FIG. 10 has a cassette stand 2A near the opening, and a stand 1F on which the container body 31 is set temporarily (hereinafter referred to as "a temporary stand 1F", when applicable) in a chamber 1E where the purging unit 3 is provided.
That is, instead of the arm handling robot 500A of the transfer robot 500, the container handling robot 80 carries the wafer cassette 70, which has been delivered from the cleaning station 200, into the casing 1 and places it on the stand portion of the purging unit 3. More specifically, the arm handling robot 500A operates to place the wafer cassette 70 on the cassette stand 2A, and thereafter the container handling robot 80 operates to carry the wafer cassette 70 from the cassette stand 2A over to the purging unit 3 and set it on the stand portion of the latter 3.
Upon selection of an empty container in the container storing section 1C, it is set on the purging unit 3 by the container handling robot 80. Under this condition, the bottom lid locking/unlocking mechanism of the purging unit 3 operates to unlock the bottom lid from the container body. As a result, only the bottom lid is left on the purge unit 3, while the container body 31 is set on the temporary stand 1F by the container handling robot 80. That is, the purging station is placed in standby state waiting for the arrival of a wafer cassette. The empty container 30 may be set on the temporary stand 1F as well as the container body 31. That is, the container unit gas-purged may be temporarily placed on it.
In the fourth example of the purging station shown in FIG. 10, one container handling robot 80 conveys the wafer cassette 70, conveys the container 30, sets the wafer cassette 70 in the container, and lifts the container body 31.
In the above-described purging stations, the container storing section 1C is provided for empty containers; however, it may be used for storing the containers gas-purged; that is, it may be used as a container clean stocker. In this case, the purging station should be provided with means for suitably discriminating the empty containers and the containers containing wafer cassettes.
FIG. 11 shows a fifth example of the purging station. In the purging station, instead of the casing 1, a closed box 20 is used. The closed box 20 has a opening 20 in a side wall 20C, through which a wafer cassette is carried in and out of the closed box 20. When a wafer cassette 70 is carried in and out of the closed body 20, the lifting stand 23 is lowered to a position as indicated by the two-dot chain line.
In the purging station of FIG. 11, similarly as in the case of the second example of the purging unit shown in FIG. 4, a bellows type skirt 29 defines a purging-chamber. The gas-purging operation is carried out under the conditions that the lifting stand 23 is raised near the uppermost position, and the bellows 29A of the skirt 29 is pushed against the rear surface of the stand portion of the upper wall of the close box 20.
In the above-described embodiment, the purging station is separate from the cleaning equipment. However, as shown in FIG. 12, the cleaning equipment 700 may have a purging function.
In FIG. 12, reference numeral 711 designates a casing; 712, a cassette carry-in opening formed in the front wall 711A of the casing 711; 713, a container carry-out opening formed in the front wall 713; 716, a cassette stand; 721 through 724, chemical solution tanks; 725, a drier; and 730, a product transferring robot with handling arms 732. The product trasferring robot 730 is engaged with a rail 731 so that it is horizontally movable. Further in FIG. 12, reference numeral 733 denotes hands which are engageable with the ears of the wafer cassette 70; 735, a product transferring robot which operates to take a wafer cassette 70 from the drier 725, and place it on the purging unit 3; and 736, a container body lifting unit.
FIG. 13 shows a second example of the cleaning equipment with the purging function.
The cleaning equipment of FIG. 13 is provided with a purging station similar to the one shown in FIG. 11. In the cleaning equipment, a opening 52 with a gas-tight door, through which a wafer cassette is carried in, is formed in the wall of the drier 725 which wall is closer to a closed box 51. The wafer cassette 70 taken out of the drier 725 is carried into the box 51 through the opening 52, and placed on the bottom lid 40 on the lifting stand 723.
The cleaning equipment shown in FIG. 13 is different from the one shown in FIG. 112 in the following points: The cleaning equipment of FIG. 13, unlike the one shown in FIG. 12, has no container body lifting equipment 736 (FIG. 12), and therefore the stroke of the lifting stand 23 is increased as much; that is, the bottom lid 40 can be moved vertically in a wider range to carry in the cassette 70.
In this case, the purging station shown in FIG. 11 may be employed as it is, being most suitable for the case where the consumption of the inert gas cannot be neglected.
FIG. 14 shows a third example of the cleaning equipment having the purging function.
A specific feature of the cleaning equipment shown in FIG. 14 resides in that the closed box is larger in volume, and the drier 25 and the wafer cassette transferring robot 735 are provided in the closed box. The drier 725 is for instance a spin drier. The wafer cassette can be dried in a purging gas atmosphere (it is applicable for employing a dry air from which a moisture is removed); that is, the drying operation and the purging operation can be achieved without exposure of the wafer cassette in the air.
FIG. 15 shows a fourth example of the cleaning equipment having the purging function. In the case of FIG. 15, the upper lid type container is employed.
The fourth example of the cleaning equipment employs the purging station shown in FIG. 8. In the casing 11, a partition wall 95 is formed to define a purge chamber 96, and a cassette or container placing opening 95A with a gas-tight door is formed in the partition wall 95.
In the cleaning equipment of FIG. 12, a wafer cassette transferring robot 735 operates to move a wafer cassette 40 from the drier 25 into the upper lid type container 60. The upper lid type container 60, after being closed by a lid operating (opening and closing) mechanism 604 and gas-purged, is taken out of the purging chamber 96 and moved out of the cleaning equipment by the wafer cassette transferring robot 735.
In the above-described embodiment, the wafer cassette 70 is stored in the clean stocker 400; however, it may be stored at a predetermined place in the clean room instead of the clean stocker 400.
It is not always necessary to store the gas-purged container in the clean stocker 400; that is, depending on the advancement of the process, it may be conveyed from the purging station to the film forming deposition system, or to a storing place provided near the latter. In this case, the container itself serves as storing means. Furthermore, the purging station may have a store room, which is used instead of the clean stocker 400.
In the above-described embodiments of the invention, the gas-purging operation is carried out by using an inert gas such as N 2 gas; however, it may be carried out by using dry air or heated N 2 gas. Sometimes the container 30 is evacuated before gas-purged (cf. FIGS. 5 and 6). In the evacuation of the container 30, in addition to the pipe 4 connected to the inert gas source, a pipe connected to a vacuum source is connected to the closed box 20.
As was described above, in the electronic substrate processing system of the invention, semiconductor substrates such as wafers are not exposed in the atmosphere in the clean room when they are conveyed from equipment to equipment or from processing station to processing station or when stored. Hence, the wafers are positively prevented from contamination, and the time limitation in operation between the equipments in the system is eliminated; that is, the processing operation is increased in the degree of freedom. Thus, the electronic substrate processing system of the invention is much higher in productivity than the conventional one.
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Disclosed is an electronic substrate processing system comprising a processing equipment for processing electronic substrates including semiconductor wafers and liquid crystal substrates; a cleaning equipment for cleaning said electronic substrate in a predetermined processing step; a portable closed container for accommodating a cassette containing said electronic substrate; a purging station for gas-purging said portable closed containers; and a storage member for storing said portable closed containers, wherein said cassette accommodates said electronic substrates which have been cleaned by said cleaning equipment being set in said portable closed container and purged with an inert gas in said purging station, and said portable closed container or containers is stored in said storing section when necessary.
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RELATED APPLICATIONS
This application is a continuation of my prior application Ser. No. 793,357, filed Jan. 9, 1992, now abandoned which was a continuation-in-part of my prior application Ser. No. 757,734 filed Sep. 11, 1991, now abandoned which was in turn a continuation-in-part of Ser. No. 506,716 filed Apr. 10, 1990, now abandoned, which was in turn a continuation-in-part of Ser. No. 381,151 filed May 2, 1989, now U.S. Pat. No. 5,009,466 dated Apr. 23, 1991 which was in turn a continuation-in-part application Ser. No. 185,707 filed Apr. 25, 1988, now abandoned.
BACKGROUND OF INVENTION
This Invention relates to high density stacking chairs of the type used by hotels for meeting room chairs. Typically, a dolly is provided which holds a stack of chairs which are stacked as densely as possible.
The use of low-cost, stacking chairs is well-known in the art. However, such chairs are designed not with comfort or ergonomics in mind, but rather to provide a large quantity of temporary seats for occasional use which can ordinarily be stored and take up minimal storage space. Such chairs may have some limited flexibility in the seat back portion, but provide no ergonomic benefits.
Considerable attention has been focused in recent years on better ergonomic designs, resulting in home and office chairs which demonstrate a wide variety of designs which include the ability to recline and provide lumbar support. See, for example, U.S. Pat. No. 4,732,424. Such ergonomic designs do not, however, provide low cost seating. Thus, it would be desirable to combine the benefits of ergonomic design into a low cost, stackable chair.
SUMMARY OF INVENTION
I have disclosed a new design for high density stacking chairs which provides exceptional comfort with exceptional stacking density by using a flexible frame which flexes to permit partial reclining of the chair back. At the same time, the partial reclining of the chair back applies pressure to the user's low back. This high density stacking flex-chair is available on the market as the Perry Chair manufactured by the Krueger International Company of Green Bay, Wis.
In one embodiment of the invention, a single continuous frame has a seat and a pivoting back attached thereto. Ergometric adjustment of the chair is accomplished by tilting of the back and flexure of the frame. Flexure of the frame urges the back into a normal upright position for stacking and uniform appearance. The back is curved and hollow, and engages the frame at upper and lower curved sections of the frame, which sections have radii of curvatures less than that of the back and which sections are positioned at a downward angle such that the effective horizontal radii of the sections in the upright position is shorter than the actual radii, causing the back to rest against the curved sections and limit forward tilting of the back. When the back is tilted, the radial movement disengages the back from the curved sections due to the difference in radii, until the angle of tilt is such that the effective radii are again equal and the back again rests against the curved sections of the frame and limits tilting backward.
In an alternative embodiment of the invention, the high density flex chair is an armchair. I have accomplished this result simply by changing the shape of the rear legs so that the chair not only has the advantage of being an armchair but also has the advantage that it can be manufactured to some extent with tooling common to the manufacturing tooling of the armless chair.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a chair built according to the present invention.
FIG. 2 is a perspective view showing a variation of a chair built according to the present invention.
FIGS. 3-5 are side plan views showing how the chair back flexes through its range of backward tilt.
FIG. 6 is a view taken across section 6--6 of FIG. 4 (seat back omitted) and represents a plan view of the chair according to the present invention in a partially tilted position.
FIG. 7 is a perspective view of a chair built according to the present invention.
FIG. 8 is a top plan view (seat back omitted) of a chair built according to the present invention in the normal rest position.
FIG. 9 is a side plan view of a stack of two chairs according to the present invention.
FIG. 10 is a rear plan view of the stack of FIG. 9.
FIG. 11 is a perspective view of an alternative embodiment of the chair of this invention illustrating in phantom a second chair stacked on top of the first chair;
FIG. 12 is a perspective view similar to FIG. 11 showing the manner in which the chair of FIG. 11 reclines;
FIG. 13 is a side elevational view of the chair and phantom chair of FIG. 11;
FIGS. 14 and 15 are top and front elevational views of the chair of FIG. 11, respectively;
FIG. 16 is an exploded view of the frame of the chair of FIG. 11, and
FIG. 17 is a detailed view of a part of FIG. 6.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, a first embodiment of a chair according to the present invention is shown. There are three major portions of the chair: a frame 10, a seat 20, and a back 30. The back 30 is curved to adapt to a user's back and is composed of a front section 32 and a rear section 34, each of which has a lip 33, 35 or other spacer which creates a hollow interior space between sections when they are attached.
The frame 10 is ideally a continuous structure, constructed of solid rod or tubular steel or the like. Alternatively, it may consist of welded or otherwise connected sections. The frame 10 has an upper curved section 12 which is enclosed within the back 30 with cylindrical bearing sections 12a at either end and which extends through the middle of the back and is angled downward. The frame 10 then extends from each end of the upper curved section 12 outward from the hollow interior, the back 30 being pivotally attached thereto at the cylindrical sections 12a. This pivotal attachment can be accomplished by bearings attached to the front section 32, but is preferably accomplished by providing bearing surfaces 12b formed on plastic molded front and back sections 32 and 34.
The frame 10 has a pair of rear support legs 16 which extend downward and rearward to a floor surface. Bottom legs 17 extend forwardly along the floor. A pair of front support legs 18 then extend upward and rearward to the front of the seat 20. The seat supporting portion 15 extends rearward supporting the seat 20, then slightly inward, then upward into the back 30, then inward, where the back is again pivotally attached at pivot connections 14a. The frame 10 continues to a lower curved section 14 which is enclosed within the back and which extends through the back at a downward angle. The distance d 1 between the opposing legs of the frame 10 as it sits on the floor is less than the width d 2 of the seat 20, so as to facilitate stacking a plurality of such chairs.
In the embodiment of FIG. 2, the seat supporting portion 15 of the frame 10 is positioned inwardly from the edges of the seat 20 and connected by welded struts 22, 23 to improve the support of the seat and lateral stability of the frame. In FIG. 7, such lateral stability can be provided by a pair of stabilizers 50, 52. Additionally, clips 24 are attached to the bottom surface of the seat 20 in order to easily attach/detach the seat to frame 10.
The back 30 is a one-piece molded unit, having openings or clips 40 which are adapted to pivotally engage the rear support legs 16 at cylindrical sections 12a. Openings or clips 42 are likewise adapted to pivotally engage the front support legs 18 at cylindrical sections 14a. In this way, the back 30 may be easily and securely fitted to frame 10. The curved sections 12 and 14 remain in a fixed position relative to frame 10 to provide pivotal limits, as will be next described.
Referring now to FIGS. 3-5, the tilting action of the back 30 is illustrated. When the chair is in its upright position, as in FIG. 3, the rear support legs 16 of the frame 10 are inclined at a forward angle so as to provide a natural spring-type action which holds the back 30 forward.
The curved sections 12 and 14 of frame 10 are parallel, each extending outward and downward from the back of the front section 32 at a twenty-two and one-half degree angle. The radii of curvature for both curved sections 12 and 14 are less than that of the back portion. But, the radius of curvature of section 12 projected at a plane inclined to the plane of section 12 by an angle of 22.5 degrees equals the radius of curvature of the back 30, such that the inside of the front section 32 is in contact with the curved sections 12 and 14 at points 36 and 37 as a result of the effective radius of the curved sections 12 and 14 being equal to the radius of the back 30.
As a user leans back on the chair, the front section 32 pivots about point 50 on the upper curved section, causing the upper half of the front section to rotate backwards, and the lower half to rotate forward about point 50. Note also that the seat 20 will be lifted by the forward rotation of the lower curved section 14. Since the back 30 has a greater radius of curvature than both curved sections, the back lifts away from the curved sections as it is tilted, reengaging the curved sections at points 38 and 39, located further down the back, where the effective radius of the back portion is again equal to the radii of the curved sections after the back has tilted 45 degrees.
A clearer view of the relationship of the curved sections 12 and 14 to the overall frame structure 10 is illustrated in FIG. 6 where the cylindrical sections of the frame 12a, 14a are providing straight bearing areas.
Stacking of the chair of the present invention is illustrated with reference to FIGS. 8-10. As can be seen in FIGS. 8 and 9, the seat supporting portions 15 of frame 10 are positioned inwardly but substantially parallel of the floor engaging or bottom portions 17 of frame 10. The rear portions of seat supporting portions 15 are angled further inward in conformance with the shape of the seat 20, and then rise upward forming lower curved section 14. The front portions of seat supporting portions 15 turn downward near the front of the seat 20 forming front support legs 18. The front support legs 18 are substantially vertical, thus remaining inward of the bottom legs 17. However, near the floor each front support leg 18 is bent outwardly at a slight angle to form into the bottom legs 17. A stacking tab 19 is welded on the outside near the bend of each front support leg 18 to provide for indexed stacking of chairs.
In FIGS. 9 and 10, chair B is stacked on top of chair A. It can be seen that the front corner of the bottom legs 17B rest on stacking tabs 19A. Further, rear stabilizer 50B, which has a radius of curvature similar to the seat 20, rests in the opening between the seat 20 and back 30. It will be noted that the upper chair B is offset forwardly from the lower chair A so that the seats of a stack of chairs will occupy a volume which extends upwardly and forwardly, and the bottom legs 17 lay outside the volume. Thus, the bottom legs 17B are wider at the front end thereof than the front legs 18A and are wider at the rear end thereof than the volume occupied by the stack of chairs, such that chair A and chair B stack tightly and neatly.
Referring now to FIG. 11, the chair illustrated therein comprises a seat 110 and a back 112 which has an upper region 114 and a lower region 116. The chair has a metal frame which is preferably made of 7/16 inch 1008 steel rod and 5/8 inch steel tube with a 3/32 inch wall thickness. The rod portion of the frame is generally the same as the frame of the armless chair with the back and bottom leg portions replaced by the tube. The frame is pivotally connected to the upper region of the back at 118 with a pivotal connection 120 between the seat 110 and the lower region 116 of the back 112.
The frame has a pair of legs each having a back leg portion 122, a bottom leg portion 124 and a front leg portion 126 which are labeled with the letters "R" and "L" for the right and left legs with the top of the front legs 126 supporting the seat 110. The pivotal connections 118 and 120 between the frame and the back 112 are preferably provided by the pivot limiting structure of the chair which is generally shown in FIGS. 3-5 and the connection between the frame and the seat 110 is preferably provided in the same manner as the connections in the commercial armless chair so that the two chairs can be made with similar manufacturing tooling.
The chair of this embodiment differs from the chair shown in FIG. 7 in that the back leg portions 122 extend from the pivot connection 118 forwardly generally outside the bottom leg portion 124 for a sufficient distance to form an arm rest 128 and then downwardly and rearwardly to the bottom leg portion 124, and the back leg portions, arms and bottom leg portions are made of tubing which slips over the rod portion of the frame and is welded to the rod at welds 121 and 125. Note that there is a slight horizontal bend in the arm 128, best seen in FIGS. 14 and 16 which position the forward part of the arm outside the bottom leg portions.
Stops are provided on the chair frame for stabilizing the chair in a stack. These stops comprise a pair of tabs 130 on the front legs 126 which support the bottom leg portions of an upper chair in the stack and a cross strut 132 (see particularly FIG. 13) which engages the top of the seat of a lower chair in the stack. Preferably the frame also has a metal tab 134 on each chair arm to which a padded armrest may be attached. As illustrated in FIG. 17, a slot 136 is provided in the tube to permit the tube to drain where the frame may be plated after welding.
While several embodiments of the chair of this invention has been described in the drawings, it will be apparent that certain modifications may be made thereof within the spirit of the following claims.
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A high density stacking flex chair is disclosed. A frame has a seat attached thereto, and a back pivotally attached thereto. The back is curved and can tilt backwards, but is limited by the frame which, through the back, has a lesser radius of curvature and is angled downward, thus providing stop action for back rotation.
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RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application Ser. No. 11/049,140, filed Feb. 1, 2005 and entitled “CLUMPING ANIMAL LITTER COMPOSITION AND METHOD OF PRODUCING THE SAME”, the contents of which are incorporated in their entirety herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates to a clumping animal litter comprising a homogenous mixture of a polymer, a gum and cellulosic components and methods of preparation thereof; particularly, an animal litter which comprises a homogenous mixture of anionic polyacylamide, guar gum, a grist and optionally cellulosic fines in combination, thereby providing a litter with enhanced absorption, clumping size and hardness.
BACKGROUND OF THE INVENTION
[0003] Methods and compositions are known that utilize absorbent materials in litter boxes and animal cages in an effort to efficiently and effectively collect animal urine and/or feces. Currently, there are generally two types of litter; clumping and non-clumping. The non-clumping type consists of an absorbent particulate material, which acts to absorb animal dross until the material reaches a saturation point, at which time the litter must be replaced. Unfortunately, without chemical additives, until the saturation point is reached the soiled absorbent material can grow mold and/or emit an objectionable odor requiring frequent replacement with fresh litter.
[0004] Clumping types of litter are currently the most popular litter on the market. In this type, the portion of the wetted granular litter forms a solid agglomerate, or clump, usually within a short period of time. This clump can then be easily removed while the rest of the granular litter remains.
[0005] Clay is currently the most commonly used absorbent material in both clumping and non-clumping types of animal litter, as it is able to absorb a substantial amount of liquid. However, due to the costs associated with mining and shipping of clays, litters made from this material tend to be more expensive and environmentally destructive than that produced from organic wood-based sources such as sawdust, waste paper, pulp, husks, wood pellets and the like. Furthermore, clays contain silica, a known carcinogen. Thus, the use of silica containing compounds raises health concerns for both the animal involved and the person changing the litter. Moreover, clumps of clay do not readily break down in water and may clog household plumping.
[0006] U.S. Pat. No. 5,927,049 to the present inventors (herein incorporated by reference in its entirety) has effectively solved these problems utilizing a simple and elegant procedure for the creation of a non-clumping, all-natural litter that is biodegradable, odor controlling, dustless, smooth throughout continued handling and capable of absorbing 5 times more fluid than clay. In particular, this invention exploits the odor neutralizing properties inherent in southern yellow pine, which eliminate volatile odors (e.g. mercaptan, amines, skatole gases) emitted from animal waste without the need for additional artificial additives.
[0007] While much of the prior art discloses the use of organic wood-based sources as a preferred or alternative embodiment, until the advent of the aforementioned method to the instant inventors few manufactures have been able to create a wood-based particulate litter that is economical to produce. These wood-based animal litters are expensive to fabricate, as they are often difficult to manufacture. Wood-based litters typically require multiple applications of aqueous additives (e.g. biocides, deodorizers, pesticides and the like), followed by a drying step in order to create litters with the desired properties.
[0008] Thus, what is lacking in the prior art is a clumping animal litter with superior absorbance and enhanced clumping properties that remains intact under mechanical stress, yet economical to produce and inhibits mold growth. Ideality the animal litter composition would use industrial or agricultural byproducts, thereby providing an economical and environmental friendly litter that is able to readily disperse when disposed into the household plumbing system.
DESCRIPTION OF THE PRIOR ART
[0009] Recently a variety of methods and procedures have been described in the prior art for preparing animal litters utilizing superabsorbent polymers in combination with both inorganic and organic substrates and mixtures of both. Many patents have been directed toward a clumping litter that forms agglomerates quickly and with sufficient mechanical integrity and size so as to permit easy removal of animal waste in a solid mass.
[0010] For example, U.S. Pat. No. 5,609,123 to Luke et al describes a pet litter composition comprising a particulate substrate with a low absorptive capacity, preferably a non-swelling clay, having bonded onto its surface fine particulate particles coated with a superabsorbent polymeric material and another particulate “clumping particle” to promote clumping. The superabsorbent polymer is an anionic polymer, preferably formed from a blend of carboxylic acid monomers, e.g. (meth)acrylic acid from 10 to 100% weight and (meth) acrylamide monomers from 0 to 90% weight. Unlike the high molecular weight, water soluble, anionic polymer utilized in the present invention, the superabsorbent polymer of Luke et al is a water insoluble, cross-linked polymeric material. Additionally, the manufacturing process of Luke et al requires that the surface of the substrate particle be sprayed first with a specific amount of liquid and allowed to absorb into the substrate particles, before application of the superabsorbent polymer and clumping particle blend. Too much liquid can cause undesirable swelling that can interfere with the beneficial performance of the superabsorbent polymer and clumping particles.
[0011] U.S. Pat. No. 6,148,768 to Ochi et al describes a pet litter for disposal of animal wastes, which comprise granular bodies containing fiber and a superabsorbent polymer skin layer. The granular body is composed of a core containing the fiber and a skin layer, which covers the core. The skin layer preferably contains an anti-powdering agent and superabsorbent polymer, such as a cross-linked polyacrylic acid. The patent fails to teach or suggest the use of a gum or gum derivatives on the granular body.
[0012] U.S. Pat. No. 4,157,696 to Carlberg describes an animal waste absorbent and deodorizing composition for use as an animal litter. The composition comprises pellets made from fly ash and cellulose fibers that form channels from the surface of the pellet to the interior of the pellet to permit capillary action to draw the dross into the interior of the pellet to deodorize and dehydrate the waste. Various pelletizing aids may be used, such as the synthetic polymer formed from sodium acrylate and acrylamide.
[0013] U.S. Pat. No. 6,662,749 to Wiedenhaft et al discloses an animal litter comprising a cellulosic substrate coated with an inner coating composed of an absorbent polyacrylate or acrylate copolymers and a second outer coating of guar gum, the binding agent used to form the aggregate. The particularly preferred polyacrylate is sold under the name Spinks 211 (H.C. Spinks Clay Company, Inc. located in Paris, Tenn.). However, unlike the instant invention, this animal litter requires the stepwise addition of an inner coating of an absorbent polymer onto the substrate with an outer coating of guar. Thus, the inner coating of polymer can only exhibit its absorbent properties when the liquid penetrates the outer coating of guar gum, which can disrupt the formation of the aggregate.
[0014] None of abovementioned prior art teach or suggest the use of a homogenous mixture of an absorbent polymer, a gum, grist and optionally cellulosic fines, to provide a clumping litter with improved clumping ability and absorbency. Thus, there remains a continuing need in the art for a clumping litter that forms a mechanically stable and absorbent agglomerate that is easy to manufacture.
DEFINITIONS
[0015] The term “anionic polyacrylamides”, as used in the present specification and claims, is intended to mean a group of water soluble, high charge density, high molecular weight macromolecules with a molecular weight of at least 5,000,000 to 30,000,000; preferably at least about 10,000,000.
[0016] The term “grist” as used in the instant specification and claims is intended to mean the milled cellulosic material produced prior the formation of the pellet during the pelletization process. The grist can be comprised of one or more sources of softwoods, e.g. pine, cedar, fir, spruce and combinations thereof, since these materials have been found to innately contain odor-neutralizing and microbial resistant properties. Moreover, the grist can be obtained in any form such as wood chips, husks, hulls, shavings or sawdust, straw and combinations thereof, preferably from materials reclaimed from outside processes (i.e. lumber yard).
[0017] The terms “cellulosic fines” and “densified wood saw dust”, are both used interchangeably in the instant specification and claims and are intended to mean the byproducts produced during the pelletization process or the superfluous cellulosic material generated during the manufacture of lumber or paper products which pass through at least one 10 to 30 mesh (U.S. Standard) screen. The cellulosic fines can include, among other things, small pellet pieces and any grist that did not form into proper pellets.
[0018] The term “near instantaneous” as used in the instant specification and claims, is intended to mean a period of time of less than 2 minutes.
[0019] The term “clump hardness” as used in the instant specification and claims, refers to the adhesiveness created by the homogenous mixture which allows the clump to remain substantially intact after being dropped from a height of one foot 5 minutes after formation of the clump.
SUMMARY OF THE INVENTION
[0020] In order to overcome the problems encountered by the prior art, the instantly disclosed invention is directed toward a clumping animal litter composition and a process of manufacturing the same. The litter is formed from cellulosic material that can be obtained from one or more sources of softwoods by any pelletizing process known in the art, for example the aforementioned method taught in U.S. Pat. No. 5,927,049 to the present inventors. During the formation of the pellets, the pellets are then moved across a sifting screen such that some of the cellulosic fines that separate from the pellets can be recycled as part of an mixture which includes an absorbent polymer (i.e. anionic polyacrylamide), dry powdered gum and grist. Alternatively, other sources of cellulosic fines generated from other manufacturing processes (e.g. lumber mill) can be used in the mixture.
[0021] It has been discovered by the present inventors that high molecular weight anionic polyacrylamides impart properties desirable in a clumping litter (i.e. faster clumping speed and clump hardness) as compared with lower molecular weight copolymers of acrylamide and acrylic acid (also known as acrylate), commonly used in the prior art. These high molecular weight macromolecules are known for their excellent absorptive capacity for aqueous media (e.g. typically upwards of 400× the weight of the polymer) with minimal tackiness.
[0022] Suitable absorbent polymers for use in the present invention include anionic polyacrylamides, a group of high charge density, water soluble, high molecular weight macromolecules produced through the polymerization of acrylamide and an anionically charged co-monomer, formed by any polymerization method known in the art. Some examples of anionically charged co-monomers include, sodium acrylate, potassium acrylate and other salts of acrylic acid and derivatives thereof known in the art.
[0023] The preferred anionic polyacrylamide is supplied under the designation CLEAROUT P6400 (manufactured by Chemtall Inc., GA, USA). CLEAROUT P6400 is a fine white powder with an approximate bulk density of 0.8 and viscosities of; 1800 cps @ concentration of 5.0 g/L; 700 cps @ concentration of 2.5 g/L; 300 cps @ 1.0 g/L, (as measured by a Brookfield viscometer at 25° C.). The intrinsic viscosity (IV) is about 22 dL/g. The dissolution time of the polymer in DI water @ 5 g/L, 25° C. is 60 minutes. The polymer has range of anionically charged co-monomers of about 20 to 40 mole %.
[0024] Examples of suitable gums or gum derivatives for use in the instant invention include guar gum. Particularly preferred guar gums include hydroxypropyl guar, carboxymethyl guar, carboxymethyl hydroxypropyl guar, and combinations and/or derivatives thereof known in the art. Other suitable gums include xanthan gum, locust bean gum and the like.
[0025] Accordingly, it is a principle objective of the instant invention to provide a clumping litter and process for the formation thereof providing a homogenous admixture of anionic polyacrylamide polymer, gum, grist and optionally, cellulosic fines, thereby providing a clumping litter with both enhanced absorption and clumping properties.
[0026] An additional objective of the invention is to produce a clump that is of sufficient hardness as to be readily removed by automated litter boxes, while able to readily disperse when introduced into the household plumbing system.
[0027] A further objective of the instant invention is to provide a manufacturing process whereby the litter produced makes use of the superfluous cellulosic fines created during the pelletization process that were heretofore unused, thereby providing a more economical and environmentally friendly product.
[0028] Another objective of the present invention is to provide an animal litter composition that has inherent odor controlling properties.
[0029] It is still a further objective of the invention to provide an animal litter composition and method of manufacture that employs industrial or agricultural byproducts, thereby providing an environmentally desirable litter.
[0030] Other objectives and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objectives and features thereof.
BRIEF DESCRIPTION OF THE FIGURES
[0031] FIG. 1 is a schematic representation of a method for producing animal litter according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0032] An illustrative, but non-limiting, example of a method that simultaneously manufactures both a non-clumping type organic fiber pellets and a clumping type organic for use as animal litter is illustrated in the schematic view 10 of FIG. 1 . As described herein, the clumping type process depends upon the by-products generated during the manufacture of the non-clumping litter, however, the grist and cellulosic fines could be obtained from other independent sources which produce grist and suitably sized cellulosic fines, i.e. lumber yards. It is noted that other conventional pelletizing apparatus and methods may be utilized.
[0033] A preferred source of the cellulosic component, preferably, albeit not limited to, shavings of yellow pine wood 12 are delivered to a receiving depot 14 where it is off-loaded and placed into a kiln 16 . Once in the kiln 16 , the wood 12 is subjected to a temperature of about 120° F. to 200° F., at low consistent humidity, for a period of time, until the desired moisture level is achieved. The kiln 16 causes the wood 12 to reach uniform moisture content, preferably less than 8%. After the wood 12 has been cured, the material is transferred to a hammer mill 18 and ground into grist 20 . The grist 20 is collected in a first surge chamber 22 . The initial curing results in dimensional variances, produced by shrinkage during drying, and are eradicated during the grinding process. This results in a grist 20 that is uniform, evenly compressible, and conducive to holding a fixed shape. Additionally, the uniform nature of the grist 20 ensures that the pellets formed therefrom will bond well together.
[0034] The grist 20 is stored in the first surge chamber 22 , until a portion of it is conveyed via a transfer feeder 24 to a conditioning chamber 26 to later form pellets 30 . While the other portion of the grist 20 ″ is transferred to a low shear mixer 50 for addition with gum, absorbent polymer and optionally cellulosic fines. The portion of the grist 20 that is transferred to the conditioning chamber 26 is sprayed with an aqueous solution, preferably steam, for approximately 3-4 seconds to form a grist 20 having uniform moisture content.
[0035] After being exposed to the aqueous solution, the moistened grist 20 ′ flows into a pellet mill 28 , where the moistened grist 20 ′ is processed into a uniform pellet 30 . During the pelletization process, the moistened grist 20 ′ is exposed to increased pressure and temperature for a short period of time. More specifically, the moistened grist 20 ′ is pressurized at about 60 Kpsi for approximately 4 to 10 seconds in the temperature range of about 180° F. to about 250° F.
[0036] The pellets 30 are then transferred to a cooler 32 where the pellet temperature drops to ambient temperature. This cooling step advantageously allows the pellets 30 to coalesce before further processing.
[0037] Once the pellets 30 have cooled, the pellets 30 pass through a shaker 34 having at least one sifting screen 36 , (e.g. a 10-mesh screen), to remove any materials that did not form into a proper pellet. As the pellets 30 move across at least one sifting screen 36 , the cellulosic fines 30 ′ are separated from the pellets 30 for later addition as part of a mixture that is combined with the grist 20 ″ in the low shear mixer 50 . Optionally, a portion or all of the cellulosic fines 30 ′ can be returned to the feeder 24 and mixed with grist 20 exiting from the first surge chamber 22 . In this way, the returned fine particles 30 ′ are combined with fresh grist 20 to form additional pellets 30 .
[0038] Pellets 30 exiting the shaker construction 34 are collected in a second surge chamber 38 , in preparation for bagging. From the second surge chamber 40 , pellets are deposited into bags 42 . The bags 42 travel on a bag conveyor 44 though a heat sealer 46 that closes the bags. The sealed bags 42 ′ are then transported to remote location for sale and use as a non-clumping animal litter.
[0039] Into the low shear mixer 50 is added at least one dry powdered gum, preferably a guar gum or guar gum derivative, at a concentration of about 5.0% to 20.0% (wt/wt), preferably at about 10% (wt/wt) based on the weight of the mixture; a dry powder of the anionic polyacrylamide polymer at a concentration of about 0.1% to about 1.0% (wt/wt), preferably at about 0.3% (wt/wt), based on the weight of the mixture; a grist at a concentration of about 100% to 30% and recycled cellulosic fines 30 ′ at about 0% to 70%, preferably about 30% (wt/wt), based on the weight of the mixture; such that the total percentage adds up to about 110%. The mixture can optionally contain any desired additive discussed below. After addition of the aforementioned components, the mixer 50 is run for a predetermined amount of time, at least 10 minutes, under conditions well known to those skilled in the art, in order to provide a uniform mixture.
[0040] The clumping litter mixture exiting the mixer 50 is collected in a third surge chamber 52 , in preparation for bagging. From the third surge chamber 52 , the mixture is released into a bagger unit 54 , wherein the mixture is deposited into bags 42 . The bags 42 travel on a bag conveyor 44 ′ through a heat sealer 46 ′ that closes the bags. The sealed bags 42 ″ are then transported to remote locations for sale and use as animal litter. Although illustrated herein as two separate conveyors and sealers, it is contemplated that the same conveyor and/or sealer can be used in the manufacture of both the clumping and non-clumping litter.
[0041] Without limiting the scope of the present invention, suitable low shear mixers include drum mixers, cement mixers, auger mixers, vibrating bed mixer or other means of mixing known in the art. These can be batch or continuous feed mixers.
[0042] It is contemplated by the instant invention to provide at least one additive during the mixing step described above, at about 0% to about 20% of the weight of the mixture. Non-limiting examples of additives include, but are not limited to oils or extracts of fragrances, antimicrobial agents, deodorants, disinfectants, colorants (i.e. pigments, dyes, lakes), and combinations thereof. Other suitable additives include oxidizers, such as sodium perborate and/or calcium peroxide, to neutralize the volatile odors (i.e. mercaptan, amines, skatole gases) emitted from the waste. Addition of at least one of the aforementioned additives during the formation of the pellet would produce pellets that comprise the characteristics of the additive throughout, e.g. color, fragrance, etc.
[0043] It is to be understood that while a certain form of the invention is illustrated, it is not to be limited to the specific form or arrangement herein described and shown. It will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown and described in the specification and drawings/figures.
[0044] One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objectives and obtain the ends and advantages mentioned, as well as those inherent therein. The embodiments, methods, procedures and techniques described herein are presently representative of the preferred embodiments, are intended to be exemplary and are not intended as limitations on the scope. Changes therein and other uses will occur to those skilled in the art which are encompassed within the spirit of the invention and are defined by the scope of the appended claims. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in the art are intended to be within the scope of the following claims.
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The instant invention is directed towards a method of preparing a clumping animal litter comprising a combination of a high molecular weight polymer, a gum, and cellulosic components. The invention particularly relates to a method of preparing a clumping animal litter that comprises a homogenous mixture of anionic polyacylamide, a guar gum, grist and optionally cellulosic fines in combination with one or more sources of cellulosic material, thereby providing a litter with enhanced absorption, clumping size and hardness.
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BACKGROUND OF THE INVENTION
[0001] This invention relates generally to a vascular implant that can be used for treatment of aneurysms, and more particularly concerns a braided flow diverter using flat-round technology to divert flow away from an entrance or neck of an intracranial aneurysm or to define a new luminal flow path through a fusiform aneurysm, as an alternative or supplement to delivery of an embolic coil within such an aneurysm.
[0002] Braided stents are typically formed from a plurality of elongate members, such as two or more metal wires, or polymeric fibers or strands of material, for example, and can be very useful in treatment of neurovascular defects. Braided flow diverting stents are commonly constructed from round wires. While the use of round wires in forming such braided flow diverting stents typically provide a maximal wall-thickness for their construction, the amount of vessel area coverage provided by such braided flow diverting stents is not maximized. Braided stents constructed of all rectangular cross-section wires can maximize vessel wall area coverage, but minimize wall thickness. Braided stents made of all rectangular cross-section wires also typically have a more limiting minimum crimped diameter for delivery than a comparable braided flow diverting stent constructed from round wires, since rectangular cross-section wires typically slide less easily past each other than comparable round wires.
[0003] It would be desirable to provide a braided flow diverting stent with an improved overall combination of axial flow disruption characteristics, wall coverage and wall thickness, compared to a braided flow diverting stent formed of all rectangular cross-section wires or formed of all round wires. It also would be desirable to provide a braided flow diverting stent that can be crimped to minimum crimped diameters for delivery, comparable to that achievable with braided flow diverting stents constructed from round wires. The present invention meets these and other needs.
SUMMARY OF THE INVENTION
[0004] Briefly and in general terms, the present invention provides for a generally tubular braided flow diverting stent formed of alternating round and rectangular elongated members, for treatment of aneurysms. The generally tubular braided flow diverting stent can be utilized to redirect blood flow away from a neck of an intracranial aneurysm, or to define a new luminal flow path through a fusiform aneurysm. The generally tubular braided flow diverting stent maintains a significant wall thickness while increasing area coverage of a vessel wall. The sliding of round elongated members over rectangular elongated members also provides very low crimped diameters to allow delivery of the braided flow diverting stent in narrow portions of the vasculature. Total wall thickness is reduced compared to a braided stent having a similar vessel wall coverage using only round wires. Axial flow disruption is improved compared to a braid of similar vessel wall coverage using only flat wires.
[0005] The present invention accordingly provides for a generally tubular braided flow diverting stent for treatment of aneurysms, including one or more first elongate members having a substantially round cross-sectional shape and helically wound in a first helical direction in a generally tubular shape, and one or more second elongate members having a substantially flat radially outer surface and helically wound in a second helical direction counter to the first helical direction and braided with the one or more first elongate members in the generally tubular shape. In a presently preferred aspect, the one or more first elongate members have a substantially circular cross-sectional shape. In another presently preferred aspect, the one or more second elongate members have a cross-sectional thickness in a first direction and a cross-sectional thickness in a second direction perpendicular to the first direction that is substantially greater than the cross-sectional thickness in the first direction. In another presently preferred aspect, the one or more second elongate members have a rectangular cross-sectional shape. In another presently preferred aspect, a plurality of first elongate members are provided, such as a plurality of first wires, for example, and a plurality of second elongate members are provided, such as a plurality of second wires.
[0006] In another presently preferred aspect, the one or more first elongate members and the one or more second elongate members may be formed of a material such as stainless steel, nickel-titanium alloy, tantalum, cobalt-chromium alloy, platinum, or combinations thereof. In another presently preferred aspect, at least a portion of the plurality of first elongate members is formed of a bioabsorbable material. In another presently preferred aspect, at least a portion of the plurality of second elongate members comprises a bioabsorbable material. In another presently preferred aspect, at least a portion of the one or more first elongate members and the one or more second elongate members may be formed of a bioabsorbable material such as poly(D,L-lactic acid-co-glycolic acid), polycaprolactone, magnesium, or combinations thereof. In another presently preferred aspect, some of the first and second elongate members optionally may be made of a radio-opaque material to facilitate guidance under imaging methods like fluoroscopy.
[0007] In another embodiment, the present invention provides for a generally tubular braided flow diverting stent for treatment of aneurysms, including a plurality of first elongate members having a substantially round cross-sectional shape and helically wound in a first helical direction in a generally tubular shape, a plurality of second elongate members having a substantially flat radially outer surface and helically wound in the first helical direction in the generally tubular shape alternatingly between the plurality of first elongate members, respectively, a plurality of third elongate members having a substantially round cross-sectional shape and helically wound in a second helical direction counter to the first helical direction and braided with the plurality of first elongate members and the plurality of second elongate members in the generally tubular shape, and a plurality of fourth elongate members having a substantially flat radially outer surface and helically wound in a second helical direction counter to the first helical direction and braided with the plurality of first elongate members and the plurality of second elongate members in the generally tubular shape alternatingly between the plurality of third elongate members.
[0008] In a presently preferred aspect, the plurality of first elongate members and the plurality of third elongate members each have a substantially circular cross-sectional shape. In another presently preferred aspect, the plurality of second elongate members and the plurality of fourth elongate members each have a cross-sectional thickness in a first direction and a cross-sectional thickness in a second direction perpendicular to the first direction substantially greater than the cross-sectional thickness in the first direction. In another presently preferred aspect, the plurality of second elongate members and the plurality of fourth elongate members each have a rectangular cross-sectional shape.
[0009] In another presently preferred aspect, the pluralities of first, second, third and fourth elongate members may be formed of stainless steel, nickel-titanium alloy, tantalum, cobalt-chromium alloy, platinum, or combinations thereof. In another presently preferred aspect, at least a portion of the pluralities of first, second, third and fourth elongate members may be formed of a bioabsorbable material selected from the group consisting of poly(D,L-lactic acid-co-glycolic acid), polycaprolactone, magnesium, or combinations thereof. In another presently preferred aspect, some of the first, second, third and fourth elongate members optionally may be made of a radio-opaque material to facilitate guidance under imaging methods like fluoroscopy.
[0010] Other features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments in conjunction with the accompanying drawings, which illustrate, by way of example, the operation of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a cross-sectional elevational schematic diagram of a first embodiment of a braided flow diverting stent according to the invention.
[0012] FIG. 2 is a cross-sectional elevational schematic diagram of a second embodiment of a braided flow diverting stent according to the invention.
[0013] FIG. 3 is a cross-sectional view taken along line 3 - 3 of FIG. 1 .
[0014] FIG. 4 is a cross-sectional view taken along line 4 - 4 of FIG. 1 .
[0015] FIG. 5 is a cross-sectional view taken along line 5 - 5 of FIG. 1 .
[0016] FIG. 6 is a cross-sectional view similar to FIG. 5 of an exemplary braided flow diverting stent constructed substantially only from round wires for purposes of comparison.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] Referring to the drawings, which are provided by way of example, and not by way of limitation, in a first embodiment, illustrated in FIG. 1 , the present invention provides for a generally tubular braided flow diverting stent 10 for treatment of aneurysms, having a proximal end 12 , a distal end 14 , and an inner lumen (not shown). The generally tubular braided flow diverting stent is preferably formed from a plurality of elongate members, is typically formed from two or more metal wires, or polymeric fibers or strands of material, for example. In a presently preferred aspect, the tubular braided stent optionally may be a self-expanding stent, formed to have a compressed configuration and an expanded configuration. In another presently preferred aspect, the tubular braided stent optionally may be formed of a shape memory material such as a nickel-titanium alloy, for example, having a shape memory position in the expanded configuration. For example, the tubular braided stent may be appropriately heat treated so that the tubular braided stent forms in the desired shape of the expanded shape memory position.
[0018] The generally tubular braided flow diverting stent includes one or more first elongate members 18 helically wound in a first helical direction in a generally tubular shape, and one or more second elongate members 20 , helically wound in a second helical direction counter to the first helical direction and braided with the one or more first elongate members in the generally tubular shape.
[0019] Referring to FIG. 4 , the one or more first elongate members preferably have a substantially round cross-sectional shape, such as a substantially circular cross-sectional shape, for example, although the one or more first elongate members may optionally have a substantially oval cross-sectional shape. The one or more first elongate members preferably also are formed of a plurality of first elongate members, such as a plurality of first wires, for example. As is illustrated in FIG. 1 , the generally tubular braided flow diverting stent can be formed with round wires wound helically in a right handed helical direction, and rectangular wires wound helically in a left handed helical direction.
[0020] Referring to FIG. 3 , the one or more second elongate members preferably have a substantially flat radially outer surface. In another presently preferred aspect, the one or more second elongate members typically have a cross-sectional height or thickness H in a first direction and a cross-sectional width or thickness W in a second direction perpendicular to the first direction substantially greater than the cross-sectional height or thickness in the first direction, and typically have a generally rectangular or flattened aspect, for example. The one or more second elongate members preferably also are formed of a plurality of second elongate members, such as a plurality of second wires, for example. The one or more first elongate members and the one or more second elongate members are preferably formed of a material such as stainless steel, nickel-titanium alloy, tantalum, cobalt-chromium alloy, platinum, or the like, or of a polymer, such as a shape memory polymer, or a bioabsorbable material such as poly(D,L-lactic acid-co-glycolic acid) (PGLA), polycaprolactone (PCL), or the like, or combinations thereof. In a presently preferred aspect, some or all of the elongated members used are composed of a bioabsorbable material. In another presently preferred aspect, some or all of the elongate members optionally may be made of a radio-opaque material to facilitate guidance under imaging methods like fluoroscopy.
[0021] Referring to FIGS. 5 and 6 , the total wall thickness of a generally tubular braided flow diverting stent according to the invention formed utilizing one or more first elongate members having a substantially round cross-sectional shape, and one or more second elongate members having a substantially flat radially outer surface, illustrated in FIG. 5 , is reduced compared to a buildup of thickness of the wall of a generally tubular braided flow diverting stent, having a similar vessel wall coverage and formed of all round wires, illustrated in FIG. 6 .
[0022] In the method of making the generally tubular braided flow diverting stent of the first embodiment, a braider machine can be loaded with bobbins of round wire in all right handed helical locations, and rectangular wire in all left handed helical locations. Conversely, a braider machine can be loaded with bobbins of round wire in all left handed helical locations, and rectangular wire in all right handed helical locations, for example.
[0023] In a second embodiment, illustrated in FIG. 2 , in which like elements are indicated by like reference numbers, the present invention provides for a generally tubular braided flow diverting stent 30 for treatment of aneurysms. The tubular braided flow diverting stent has a proximal end 32 , a distal end 34 , and an inner lumen (not shown), and is preferably formed from a plurality of elongate members, typically formed from two or more metal wires, or polymeric fibers or strands of material, for example. In one presently preferred aspect, the tubular braided stent optionally may be a self-expanding stent, formed to have a compressed configuration and an expanded configuration. The tubular braided flow diverting stent can be formed of a shape memory material such as a nickel-titanium alloy, for example, having a shape memory position in the expanded configuration. For example, the tubular braided flow diverting stent may be appropriately heat treated so that the tubular braided flow diverting stent forms in the desired shape of the expanded shape memory position.
[0024] The generally tubular braided flow diverting stent of the second embodiment preferably includes a plurality of first elongate members 38 helically wound in a first helical direction in a generally tubular shape, a plurality of second elongate members 40 helically wound in the first helical direction in the generally tubular shape alternatingly between the plurality of first elongate members, a plurality of third elongate members 42 helically wound in a second helical direction counter to the first helical direction and braided with the plurality of first elongate members and the plurality of second elongate members in the generally tubular shape, and a plurality of fourth elongate members 44 helically wound in a second helical direction counter to the first helical direction and braided with the plurality of first elongate members and the plurality of second elongate members in the generally tubular shape alternatingly between the plurality of third elongate members. For example, as is illustrated in FIG. 2 , the generally tubular braided flow diverting stent can be formed with alternating round wires and rectangular wires wound helically in both right handed and left handed helical directions.
[0025] Referring to FIG. 4 , the plurality of first elongate members preferably have a substantially round cross-sectional shape, such as a substantially circular cross-sectional shape, for example, although the one or more first elongate members may optionally have a substantially oval cross-sectional shape, and can be formed by a plurality of first wires, for example.
[0026] Referring to FIG. 3 , the plurality of second elongate members preferably have a substantially flat radially outer surface. In another presently preferred aspect, the one or more second elongate members typically have a cross-sectional height or thickness H in a first direction and a cross-sectional width or thickness W in a second direction perpendicular to the first direction substantially greater than the cross-sectional height or thickness in the first direction, and typically have a generally rectangular or flattened aspect, and can be formed by a plurality of wires, for example.
[0027] Referring to FIG. 4 , the plurality of third elongate members preferably have a substantially round cross-sectional shape, such as a substantially circular cross-sectional shape, for example, although the one or more first elongate members may optionally have a substantially oval cross-sectional shape, and can be formed by a plurality of wires, for example.
[0028] Referring to FIG. 3 , the plurality of fourth elongate members preferably have a substantially flat radially outer surface. In another presently preferred aspect, the one or more fourth elongate members typically have a cross-sectional height or thickness H in a first direction and a cross-sectional width or thickness W in a second direction perpendicular to the first direction substantially greater than the cross-sectional height or thickness in the first direction, and typically have a generally rectangular or flattened aspect, and can be formed by a plurality of wires, for example.
[0029] The pluralities of first, second, third and fourth elongate members are preferably formed of a material selected from the group consisting of stainless steel, nickel-titanium alloy, tantalum, cobalt-chromium alloy, platinum, and the like, or of a polymer, such as a shape memory polymer, or a bioabsorbable material such as poly(D,L-lactic acid-co-glycolic acid) (PGLA), polycaprolactone (PCL), or the like, and combinations thereof. In a presently preferred aspect, some or all of the elongated members used are composed of a bioabsorbable material. In another presently preferred aspect, some or all of the elongate members optionally may be made of a radio-opaque material to facilitate guidance under imaging methods like fluoroscopy.
[0030] In the method of making the generally tubular braided flow diverting stent of the second embodiment, a braider machine can be loaded with alternating bobbins of round and rectangular wire in both the right handed and left handed helical locations.
[0031] It will be apparent from the foregoing that while particular forms of the invention have been illustrated and described, various modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited, except as by the appended claims.
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A generally tubular braided flow diverting stent is formed of alternating round and rectangular elongated members, for treatment of aneurysms. The generally tubular braided flow diverting stent maintains a significant wall thickness while increasing area coverage of a vessel wall. Sliding of the round elongated members over the rectangular elongated members allows the stent to be crimped to very low diameters for delivery in narrow portions of the vasculature.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dry etching method for etching a film having a multilayered structure including an insulation film such as silicon oxide film, and a film of tungsten, molybdenum, or a silicate of each, formed on the insulation film, or a structure including a film of one of those high melting point metal and a polycrystal silicon film.
2. Description of the Related Art
In accordance with higher integration density of semiconductor devices, size of circuits is rapidly reduced. However, such reduction in size creates a number of problems, particularly in the case where its gate electrode or wire is made of:
(1) a metal having low resistivity and melting point, such as aluminum (Al);
(2) a semiconductor material such as polycrystal silicon; or
(3) a metal having a high melting point, such as tungsten (W) or molybdenum (Mo).
Regarding case (1) where Al is used as the gate electrode, since the melting point of Al is close 660° C., a heating process cannot be applied after deposition of Al during the course of forming an element. As a result, by use of Al, it is difficult to achieve a multilayered structure, and the integration density of such a structure cannot be increased. Further, after formation of the Al electrode, a diffusion process, which requires a high temperature of about 1000° C., cannot be performed. Therefore, the gate electrode must be formed after diffusion of the source drain region during the course of manufacturing MOSFETs. However, a certain amount of mask matching allowance has to be set between the gate electrode and the source-drain region, thereby decreasing the integration density of the structure. Further, the combined capacitance of the gate and the source, or the drain, is increased.
Regarding case (2) where polycrystal silicon is used as the gate electrode, the gate, source, and drain regions can be formed in the form of mask such that they self-matches with each other, and polycrystal silicon is relatively stable in a heating process; therefore wiring can be carried out in a multilayered manner, thereby achieving a high integration density. However, a polycrystal silicon film has a resistivity (specific resistance), and therefore it is necessary to add appropriate impurities to the film to decrease its resistance.
In reality, even if the impurities are added, the resistivity can be decreased only to 1×10 ○ 19 Ω cm, which is still very high as compared to 1×10 -6 II Ω cm of W or 1×10 -5 I Ω cm of Mo. Consequently, when circuit elements on a semiconductor are connected with each other by means of the polycrystal silicon film, transmission of a signal becomes so slow that the operation speed is limited. Similarly, when polycrystal silicon is used as a gate electrode of a MOSFET, the resistance-capacitance product becomes large due to its large resistance. Consequently, it takes long time to raise the voltage of the gate up to a set operation voltage, thereby reducing the operation speed.
Regarding case (3) where a high melting point metal such as W is used as a gate, despite of its high resistivity, W is relatively stable in a heating process of 1000° C., which is required during the course of forming semiconductor devices, because W has a very high melting point. However, as in the case of metals in general, W cannot withstand a process in a high-temperature and oxidating atmosphere.
As described, a satisfactory gate electrode cannot be formed in either of the above described cases. Some of the criteria for a good gate electrode are: the gate electrode is made of a crystal material having a small grain size., the surface of the electrode can be easily stabilized; the chemical resistance thereof is high; the contactibility thereof against Al or an Si substrate is high; and the anti-electromigration property is high.
In the meantime, use of a gate material having a multilayered structure of a metal silicide film such as tungsten silicide (WSi 2 ) and a polycrystal silicon film has been proposed for manufacturing a semiconductor device having the above-mentioned characteristics, namely a high integration density of polycrystal silicon gate electrode MOSFET, high stability and reliability of the MOSFET in a heating process during the course of manufacture, a low resistivity of the semiconductor device as compared to polycrystal silicon, and a high-speed operability of the device. Moreover, a multilayered structure of a high melting point metal such as tungsten and a polycrystal silicon film has been also proposed.
However, methods which deal with such multilayers have the following problems. In accordance with reduction in size of circuits, gate electrodes are minimized. Accordingly, gate insulation films formed underneath the gate electrodes have been thinned to about 10 nm. Therefore, the processability of a gate electrode depends not on its high melting point metal silicide film crystal, but on its polycrystal silicon film. If a desired shape is not obtained, i.e., the end of a silicon film cannot be withdrawn from the level of the end of a silicide film, deviation of the channel length occurs. Further, as the etching selection ratio between an oxidation silicon film serving as the gate insulation film and a polycrystal silicon film serving as the gate electrode is a main factor for determining the yield of products, an etching process must be carried out based on a high selection ratio between the oxidation silicon film and the gate insulation film. Thus, the process for forming a gate electrode entails a difficult problem.
There have been many reports on etching of a high melting point metal such as tungsten. Some of the examples are D. W. Hess (Tungsten Etching and CF 4 and SF 6 Discharges: Journal of the Electrochemical Society: January 1984, pages 115-120), Picard et al. (Plasma Etching of Refractory Metals (N. Mo. Ta) and Silicon in SF 6 and SF 6 -O 2 : Plasma Chemistry and Pasma Processing Vol. 5, No. 4 1985, pages 335-351), and E. Degenkolb et al. (Selective Dry Etching of W for VLSI Metalization: Journal of the Electro-chemical Society 167, Society Meeting Vol. 85-1, 1985, page 353). In each report, an etching gas containing fluorine (SF 6 , CF 4 , CF 3 Br or the like) are used. However, with a multilayered structure of a tungsten silicide and a polycrystal silicon, or a heat-oxidation film, a variety of problems, which do not occur with a tungsten single layer, rise during the processing step.
Meanwhile, Chi-Hwa et al. (Anisotropic Plasma Etching of Tungsten: U.S. Pat. No. 4,713,141, Dec. 15, 1987) a method of directionally etching a multilayer of a high melting point metal (for example, W) and a silicon or an insulation film. In this report, tungsten is etched by use of a mixture gas of SF 6 and Cl 2 , which serves as an etching gas. According to the method disclosed, Cl, which can suppress reaction between tungsten and SF 6 , is adhered on the side surface of an etching pattern, thereby realizing a directional etching.
However, in a practical sense, good etching cannot be performed by use of a fluorine containing gas such as sulfur hexafluoride (SF 6 ) or a mixture gas of a fluorine-containing gas and a carbon tetrachloride (CCl 4 ) or Cl 2 , which is a conventionally used etching gas for a metal silicide film, because the selection ratio of these gas against silicon oxide is not sufficient as 10 or less.
Further, conventionally, a reactive ion etching technique is employed to etch a polycrystal silicon film. However, in the case where an anode coupling?? mode is employed for patterning, the selection ratio becomes large, but the processed shape will be undesirable, whereas in the case where a cathode coupling mode is used, the selection ratio becomes small, but the desirable shape can be obtained.
Moreover, it is also important that the etching proceeds at the same speed anywhere in a wafer surface. For example, if the etching proceeds faster in the periphery portion of the wafer than in the center portion, a problem occurs, that is, when etching is carried out until the center portion of the polycrystal silicon is completely removed, some of the underlying silicon oxide film in the periphery portion has been already etched.
In the case where the selection ratio against the silicon oxide is low, etching of the periphery portion of the silicon oxide proceeds until the gate insulation film is damaged. Further, since the etching resultants of the periphery and center portions differ from each other, the characteristics of plasma itself are changed. Consequently, an appropriate shape cannot be obtained.
As described, in the conventional process of a multilayer film formed on a silicon oxidation film, consisting of a high melting point metal or a silicide of the metal and a polycrystal silicon, it is difficult to realize an etching sufficient in terms of processed shape, selection ratio, and uniformity.
SUMMARY OF THE INVENTION
The present invention has been proposed in consideration of the above-described circumstance, and the purpose thereof is to provide a dry etching method for achieving an excellent processed shape and sufficient selectivity, in process of a multilayer film formed on a silicon oxidation film or the like, consisting of a high melting point metal or a silicide of the metal and a polycrystal silicon.
The main feature of the invention is to select the most suitable type of gas in the dry etching process, and set the best possible etching condition for processing the above-mentioned multilayer film.
According to the present invention, there is provided a dry etching method, wherein a multilayer film including on selected from the group consisting of tungsten, molybdenum, a tungsten silicide, and a molybdenum silicide, as the first layer, and polycrystal silicon as the second layer underlying is formed on a silicon oxide insulation film, a processed substrate prepared by forming a mask pattern on the multilayer film is placed in a vacuum container, an etching gas is introduced into the vacuum container, and an electrical discharge is induced by applying an electrical field to the vacuum container, thereby anisotropically etching the multilayered film in accordance with the mask pattern, comprising:
the first etching step for etching the first layer by use of the first gas which is selected from the group consisting of fluorine, sulfur hexafluoride, and nitrogen trifluoride, or a mixture gas consisting of the first gas and the second gas which is one selected from the group consisting of hydrogen chloride, hydrogen bromide, chlorine, bromine, and carbon tetrachloride, as an etching gas; and
the second etching step for etching the second layer by use of the second gas, or a mixture gas of the second gas and the third gas which is selected from the group consisting of an inert gas, nitrogen gas, oxygen gas, silicon tetrachloride gas and carbon monoxide gas, as an etching gas.
In the first etching step, etching of the first step should preferably be carried out under the conditions that a mixture gas containing sulfur hexafluoride and chloride is used as an etching gas, the mixture ratio of sulfur hexafluoride and chlorine is set between 4:6 and 7:3, the gas flow amount is set between 20 and 150 sccm, and the high frequency power density is set between 0.4 and 0.9W/cm 2 .
In the second etching step, the amount of the third gas added to the second gas should preferably be in the range between 0 and 10 volume % of the whole etching gas, the third gas being one selected from the group consisting of inert gas, nitrogen gas, oxygen gas, silicon tetrachloride gas, and carbon monoxide gas.
Further, in the first etching step, the third gas which is one selected from the group consisting of inert gas, nitrogen gas, oxygen gas, silicon tetrachloride gas, and carbon monoxide gas, may be added to the etching gas in an amount of the range between 0 and 10 volume % of the whole etching gas.
The first and second etching process should be carried out while maintaining the temperature of the to-be-processed substrate in the range between -10° and -120° C., more specifically, between -30° and -60° C. The pressure of the etching gas should preferably be set between 50 and 150 m Torr.
Further, the first etching process may be performed while detecting the end point of the etching by monitoring light emitted from the reactive substances, pressure change of the reaction resultants, plasma impedance or the like. More specifically, in the step of etching the first layer, the end point of etching is detected by monitoring light emitted from tungsten, molybdenum, or a molybdenum fluoride. Similarly, in the step of etching the second layer, the end point is detected by monitoring light emitted from chlorine, bromine, silicon chloride, or silicon bromide.
Even after etching the first layer, the etching may be continued to etch the underlying polycrystal silicon until complete removal of the first layer.
Moreover, according to the invention, there is further provided a dry etching method, wherein a thin film including one selected from the group consisting of tungsten, molybdenum, a tungsten silicide, and a molybdenum silicide, as the first layer, is formed on a silicon oxide insulation film, a to be-processed substrate prepared by forming a mask pattern on the thin film is placed in a vacuum container, an etching gas is introduced into the vacuum container, and an electrical discharge is induced by applying an electrical field to the vacuum container, thereby anisotropically etching the thin film in accordance with the mask pattern, characterized in that the first layer is etched while maintaining the temperature of the to-be-processed substrate in the range between -10° and -120° C. by use of: the first gas which is one selected from the group consisting of fluorine, sulfur hexafluoride, and nitrogen trifluoride; or a mixture gas containing the first gas and the second gas which is one selected from the group consisting of hydrogen chloride, hydrogen bromide, chlorine, bromine, and carbon tetrachloride; or a mixture gas containing the first and second gases, and the third gas which is one selected from the group consisting of an inert gas, nitrogen gas, oxygen gas, silicon tetrachloride gas and carbon monoxide gas; or a mixture gas containing the first gas and the third gas, as an etching gas.
The inventors of the present invention conducted a variety of experiments regarding etching of a multilayer film formed on an silicon oxide film, and including a tungsten silicide film as the upper layer, and a phosphor-containing polycrystal silicon film as the lower layer, and has discovered the following fact.
In reactive dry etching of a tungsten silicide by use of SF 6 gas, the etching speed when the temperature of the substrate is 25° C., is as fast as 300-400 nm/min. Thus, high-speed etching can be achieved. However, in such a case, side etching of the tungsten silicide film and the underlying polycrystal silicon is unavoidable. Such side etching can create problems, especially where the size of the elements becomes smaller and smaller.
On the other hand, in the case where the tungsten silicide is subjected to a reactive dry etching by use of Cl 2 gas, the etching speed when the temperature of the substrate is 25° C., is as slow as 50-100 nm/min.
Further, the substrate-temperature dependency of the etching speed was examined with regard to the case where a tungsten silicide is etched by use of SF 6 gas. The etching speed decreases in proportional to the inverse number of the substrate temperature, but at the substrate temperature of 30° C., the etching speed was still as fast as 230-370 nm/min. In this case, side etching did not occur to the pattern of the tungsten silicide, and therefore a vertical shape was obtained. However, side etching occurred to the underlying polycrystal silicon to a certain level.
From the results obtained, it was confirmed that when 40-70% of Cl 2 gas is added to SF 6 while maintaining the substrate temperature at -30° C., side etching does not occur to tungsten silicide and polycrystal silicon, enabling a pattern formation of a vertical shape. This phenomenon can be explained as follows:
Even in such a cool condition of the substrate as mentioned, the vapor pressures of WF 6 , SiF 4 , and the like, generated by combining tungsten and silicon atoms of the tungsten silicide, and fluorine with each other, are high, and therefore side etching occurs. Meanwhile, the vapor pressure of WCl 5 or WCl 6 , generated by combining tungsten and chlorine together, is very low, and therefore removal of the film is difficult. Consequently, the etching speed is slow when Cl 2 is used, and it is likely to create a deposit. Thus, by mixing an appropriate amount of Cl 2 into the fluorine-containing gas such as SF 6 , the etching speed of a satisfactory level can be maintained, and a deposition layer of WCl x (x=5, 6) is selectively formed on the side wall of the pattern. Therefore, reaction between fluorine or tungsten, and silicon atoms is suppressed, thereby forming a vertically shaped pattern.
It should be noted that when etching a multilayer structure including tungsten silicide, polycrystal silicon, and an silicon oxide film, the etching speed for the silicon oxide can be significantly increased by adding a small amount of SF 6 . Accordingly, if the etching selection ratio between polycrystal silicon and the silicon oxide film is small, and the etching speed within the wafer surface cannot be sufficiently uniformed, the oxide silicon film is completely etched at a section of the wafer surface.
In etching of the polycrystal silicon by use of Cl 2 gas, when the substrate temperature is low, the etching speed does not become so slow, and a sufficient selection ratio against the underlying silicon oxide film can be obtained. Accordingly, it was confirmed that etching which can achieve a desired vertical shape and a uniform etching speed within a wafer surface, can be carried out with the above-described condition.
In the meantime, by use of a spectrometer, each etching step was analyzed with regard to emission of light. More specifically, the peak value in connection with tungsten or tungsten silicide in the first step, and the peak value in connection with Cl 2 in the second step were detected to find out the end point of etching. It was confirmed that with this end point detecting technique, each etching step can be controlled at an extremely high accuracy.
By use of the technique, the temperature of the to-be-processed substrate is cooled down to -60° C., and etching of the tungsten silicide film was conducted as in the first step. Here, it was possible to etch the film into a vertical shape by use of solely SF 6 . After that, maintaining the substrate temperature at -60° C., the polycrystal silicon film was etched by use of solely Cl 2 as in the second step. Here, it was also possible to etch the polycrystal silicon film into a vertical shape, and to obtain a sufficient selection ratio between the polycrystal silicon and the silicon oxide. Accordingly, it was confirmed that it is possible to etch a film into a vertical shape both in the periphery and central portions of a wafer.
In accordance with decrease in wafer temperature, the selectivity between the polycrystal silicon and the silicon oxide film was significantly improved. Further, there were no residuals or deposits observed.
As described, first, a tungsten silicide film is etched by solely SF 6 gas, or a gas mixture of Cl 2 and SF 6 until there is no etching residuals, and then, a polycrystal silicon film is etched by a gas mainly containing Cl 2 . Thus, etching having a high selectivity against the silicon oxide can be achieved, and the overlaying tungsten silicide and the underlaying polycrystal silicon can be appropriately etched without side etching, or residuals such as deposits. Further, since the overlaying and underlaying films can be etched at the same wafer temperature, the procedure of the etching method is simplified, thereby improving the efficiency.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention.
FIG. 1 is a schematic view showing a structure of a dry etching device used in an embodiment method according to the present invention;
FIGS. 2A-2C are cross sections of a material at several stages of the pattern formation step in the embodiment method according to the invention;
FIG. 3 is a characteristic diagram showing the correlation between a mixture ratio of gases, and an etching speed;
FIG. 4 is a characteristic diagram showing the correlation between the temperature of a lower electrode and an etching speed;
FIGS. 5A-5F are cross sections of etched shapes when etched as shown in FIG. 3;
FIGS. 6A-6C are cross sections of etched shapes with a variety of gas mixture ratios;
FIG. 7 is a characteristic diagram showing the correlations between a high frequency power and an etching speed, and between the high frequency power and the uniformity of the etching speed;
FIG. 8 is a characteristic diagram showing the correlations between a pressure, and an etching speed, and between the pressure and the uniformity of the etching speed;
FIG. 9 is a characteristic diagram showing the correlations between a gas flow amount, and an etching speed, and between the gas flow amount and the uniformity of the etching speed;
FIG. 10 is a characteristic diagram showing the correlations between a mixture ratio of gases, and an etching speed, and between the mixture ratio and the uniformity of the etching speed;
FIG. 11 is a characteristic diagram showing the correlations between a high frequency power, and an etching speed, and between the high frequency power and the uniformity of the etching speed;
FIGS. 12A and 12B are cross sections of etched shape of a semiconductor wafer, designed for comparison;
FIG. 13 is a characteristic diagram showing the correlations between a gas pressure, and an etching speed, between the gas pressure and the uniformity of the etching speed, and between the gas pressure and the selection ratio;
FIG. 14 is a schematic view of a structure of a dry etching device of a plasma etching mode, which is applicable to the present invention; and
FIG. 15 is a schematic view of a structure of a dry etching device of a reactive ion etching mode, which is applicable to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will now be explained in detail with reference to embodiments shown in accompanying figures.
FIG. 1 is a schematic view showing a structure of a dry etching device used in a method according to the present invention. The device includes an etching chamber 10 of a vacuum container, an inlet preparatory chamber 20, and an outlet preparatory chamber 30, connected with each other in series. A gate valve 21 is provided between the etching chamber 10 and the inlet preparatory chamber 20 so as to close the connection therebetween, and a gate valve 31 is between the inlet and outlet preparatory chambers 10 and 20 so as to close the connection therebetween.
In the inlet preparatory chamber 20, a substrate mounting base 23 is provided, and similarly, another substrate mounting base 33 is provided in the outlet preparatory chamber 30. While maintaining the vacuum state in the etching chamber 10, a to-be-processed substrate 11 can be input to the inlet preparatory chamber 20 through the gate valve 22, or output from the outlet preparatory chamber 30 through the gate valve 32. Thus, influences by moisture, oxygen, or the like in the atmosphere, can be avoided.
In the etching chamber 10, there is provided the first electrode 12 on which the to-be processed substrate 11 is mounted. A high frequency power source 14 is connected to the electrode 12 via a blocking diode 13, and the high frequency voltage of 13.56 MHz is applied to the electrode 12. An electrostatic chuck (not shown) for fixing the substrate 11 is provided on the electrode 12, and the temperature of the chuck is controlled by a cooling tube 15. The periphery of the electrode 12 is covered by a ring 50 made of carbon so that the electrode is not etched by plasma.
The upper wall of the etching chamber 12 serves as an opposite electrode 10a (second electrode) to the first electrode 12. A permanent magnet 18 is set on the upper portion of the second electrode 10a, and the magnet 18 is rotated by a motor 18. The magnetic flux density in the surface portion of the substrate 11 can be varied in the range between 60 and 120 [G] by changing the magnetic force of the permanent magnet 18. Further, the inner wall surface of the etching chamber 10 is heated by a heater (not shown) to a predetermined temperature.
To the etching chamber 10, connected are a chlorine gas supplying line a, an oxygen supplying line b, an SF 6 supplying line d, and an F 2 supplying line e. Valves 16a-16e and flow amount adjusters 17a-17e are set in the respective gas supplying lines a-e so as to control the flow amount and gas pressure of each line. With the above-described structure, a predetermined gas is introduced into the etching chamber 10, and then a high frequency voltage is applied between the first and second electrodes 12 and 10a to induce electrical discharge therebetween.
It should be pointed out that an end point detector 34 for detecting the end point of etching for each of the first and second layers may be provided as indicated by the broken lines in the figure, in the outer side of the gate valve 31. The end point detector 34 may be of the type in which change in light emitting amount corresponding to the wavelength of a resultant of reaction is detected to locate its end point, or the type in which pressure change of the resultant of reaction is detected, or the type in which change in plasma impedance is detected.
An etching method by use of the above-described device will be described.
As can be seen in FIG. 2A, 10 nm-thick silicon oxide (SiO 2 ) film 41 is formed on a silicon substrate 40 by heat oxidation, and a 150 nm polycrystal silicon film 42 is deposited thereon by the CVD method. Phosphor is then diffused into the polycrystal silicon film 42 to form an N-type polycrystal silicon film, on which a 200 nm-thick tungsten silicide (WSi 2 ) film 43 is formed by the spatter deposition method. After that, a resist pattern 44 is formed on the formed layer. The resist pattern 44 is prepared by coating a substrate surface with a photosensitive resist made of novolak resin, and the coat is selectively removed into a desired pattern by the lithography method.
Thus formed substrate 11 to be processed is placed on the electrode 12 of the dry etching device shown in FIG. 1, and the WSi 2 film 43 is selectively etched by a method later explained as shown in FIG. 2. Further, the polycrystal silicon film 42 is selectively etched as shown in FIG. 2C.
The method of etching the WSi 2 by use of the device shown in FIG. 1 will be explained.
FIG. 3 is a graph showing the correlation between the mixture ratio of a mixture gas and an etching speed, where an SF 6 and Cl 2 mixture gas having a particular mixture ratio was introduced to the etching chamber 10 to etch the WSi 2 film 43, the polycrystal silicon film 42, the SiO 2 film 41, and the resist 44, and gas 10, and the etching speed for etching each of the layers, which varies along with a mixture ratio of the mixture gas, was examined.
Here, the partial pressures of the Cl 2 gas and SF 6 gas were changed while maintaining the pressure in the etching chamber 10 at constant (75 m Torr), and also the total flow amount at 100 sccm. The temperature of the electrode 12 was -30° C., and the high frequency power was 100W (power density: 0.57W/cm 2 ). The side walls of the etching chamber 10, and the upper electrode 10a were heated up to 60° C. The etching time was 1 minute. In FIG. 3, ◯ denotes the etching speed for WSi 2 , Δ for resist, for polycrystal Si, and □ for SiO 2 .
As is clear from FIG. 3, the smaller the mixture ratio of Cl 2 , the faster the etching speed in the WSi 2 , polycrystal Si, SiO 2 , and resist layers. Especially, the etching speed in the polycrystal Si layer significantly increases as the mixture ratio of Cl 2 drops to 40% or lower, whereas the etching speed does not greatly change when the ratio of 40% or more.
By use of Cl 2 gas (100%), the etching speed with regard to SiO 2 is 12 nm/min, whereas by use of 80% Cl 2 gas, the etching speed is 36 nm/min. Thus, the etching speed is increased by a small amount of SF 6 added. Meanwhile, in etching of the WSi 2 layer, a deposit is created in Cl 2 gas (100%), and the etching speed is quickly decreased.
Next, the lower electrode temperature dependency of the etching speed with regard to each of the WSi 2 film, photoresist, and SiO 2 film, by use of SF 6 as the etching gas, at the high frequency power of 100W, the pressure of 75 m Torr, and the flow amount of 100 sccm. The results were plotted on the graph shown in FIG. 4. In FIG. 4, ◯ denotes the etching speed for WSi 2 , Δ for resist, and SiO 2 .
As can be seen in FIG. 4, in accordance with decrease in temperature of the lower electrode, the etching speed with regards to each of WSi 2 , resist, and SiO 2 somewhat slowed down. In the case of WSi 2 , the etching speed was about 350 nm/min at the lower electrode temperature of 25° C., whereas about 300 nm/min at -30° C. No significant drop was observed. Similarly, in the case of SiO 2 , the etching speed was 70 nm/min at the lower electrode temperature of 25° C., whereas 60 nm/min at -30° C., and thus no significant drop was observed.
FIGS. 5A-5F show pattern shapes of the WSi 2 film etched at several lower electrode temperatures. In these figures, alike elements are denoted by the same reference numerals as of FIG. 2A, such as silicon substrate 40, 10 nm-thick silicon oxide (SiO 2 ) film 41, 150 nm-thick polycrystal silicon film 42, 200 nm-thick tungsten silicide (WSi 2 ) film 43, and resist pattern 44. FIGS. 5A-5F show the cases where the lower electrode temperature (or substrate temperature) was 25° C., 0° C., -10° C., -30° C., -120° C., and 150° C., respectively.
It can be understood from the figures that the lower the power electrode temperature, the smaller the amount of side etching of the pattern. In the case where the lower electrode temperature was -30° C., etching of the WSi 2 into a vertical shape was possible by use of solely SF 6 gas. At a temperature of -10° C., the side etching amount was 10% at the most, which is in the range of general allowance for patterning. Meanwhile, at a temperature of -10° C. or lower, side-wall deposits 45 were created to deform the pattern (fattening the bottom portion). Thus, the substrate should preferably be in the range between -10° C. and -120° C.
FIGS. 6A-6C show SEM observed cross sections of a material having a WSi 2 /polycrystal Si multilayer structure etched at a variety of mixture ratio of Cl 2 and SF 6 under the same conditions as those of FIG. 3. In these figures, alike elements are denoted by the same reference numerals as of FIG. 2A, such as silicon substrate 40, 10 nm-thick silicon oxide (SiO 2 ) film 41, 150 nm-thick polycrystal silicon film 42, 200 nm-thick tungsten silicide (WSi 2 ) film 43, and resist pattern 44. FIGS. 6A-6C show the cases where the SF 6 gas was 100%, 40-70%, and the Cl 2 gas was 100%, respectively.
As can be understood from this figure, with the 100% SF 6 , under-cut occurred to the polycrystal film 42 as shown in FIG. 6A. The amount of under-cut decreased along with addition of Cl 2 , and when the amount of Cl 2 was 40%, no under-cut was observed. As shown in FIG. 6B, when the amount of Cl 2 added was 40-70%, a substantially vertical shape was manufactured.
With further increase in the amount of Cl 2 added, the pattern of the polycrystal silicon film 42 and the WSi 2 film 43 was deformed into a fattened bottom. When Cl 2 was 100%, deposits 45 were created on the side wall of the pattern as shown in FIG. 6C. The created deposits are expected to be tungsten chlorides, which were contained in the WSi 2 film, such as tungsten pentachloride (WCl 5 ) and tungsten hexachloride (WCl 6 ), and these chlorides were deposited due to a low vapor pressure.
A variety of experiments were conducted with regard to the etching speed in a wafer surface, and the uniformity thereof. More specifically, the etching speed for the WSi 2 film of a wafer surface, and the uniformity thereof were measured under the variable conditions of, namely, the high frequency power, pressure, total flow amount, and mixture ratio of Cl 2 /SF 6 . The results were as shown in FIGS. 7-10. In these figures, ◯ denotes the uniformity of an etching speed, and denotes an etching speed. The temperature of the lower electrode was fixed to -30° C. Under the above conditions, it was found that the etching speed is faster in the periphery of a wafer than the center portion thereof, in all cases.
FIG. 7 is a graph showing the etching speed for the WSi 2 and the uniformity thereof, at the mixture ratio between Cl 2 and SF 6 (Cl 2 /Cl 2 +SF 6 ) fixed to 60%, the total flow amount to 100 sccm, and the pressure to 75 m Torr, along with a variable high frequency power. As can be understood from this figure, the etching speed becomes faster as the high frequency power increases, whereas the uniformity thereof is lowered. Further, the figure indicates that to achieve a uniformity of 20% or less, which is within the range of allowance for patterning of a gate electrode or the like, the high frequency power should be set to 160W or less, and to achieve an etching speed of 100 nm/min or higher, the high frequency power should be set to 70W or higher. It should be noted that 70-160W of power is equivalent to 0.4-0.9W/cm 2 of power density in consideration of the size (6 inches) of the wafer used in this experiment.
FIG. 8 is a graph showing the etching speed for the WSi 2 and the uniformity thereof, at the mixture ratio between Cl 2 and SF 6 (Cl 2 /Cl 2 +SF 6 ) fixed to 60%, the total flow amount to 100 sccm, and the high frequency power to 75W, along with a variable pressure. As can be understood from this figure, the etching speed does not change even if the pressure is varied, whereas the uniformity thereof is improved when the pressure is raised. However, at a pressure of 100 m Torr or higher, under-cut occurs to the WSi 2 film pattern, and therefore a desired shape cannot be obtained.
FIG. 9 is a graph showing the etching speed for the WSi 2 and the uniformity thereof, at the mixture ratio between Cl 2 and SF 6 (Cl 2 /Cl 2 +SF 6 ) fixed to 60%, the high frequency power to 75W, and the pressure to 75 m Torr, along with a variable total flow amount. As can be understood from this figure, the etching speed does not change as the flow amount is varied, whereas the uniformity thereof improves as the flow amount becomes smaller. When the flow amount was decreased to less than 20 sccm, formation of deposits on the side wall of the resist pattern was observed, whereas when the flow amount exceeded 150 sccm, the uniformity went over 20%. Therefore, the flow amount of a mixture gas introduced into the etching chamber should preferably be 20-150 sccm.
FIG. 10 is a graph showing the etching speed for the WSi 2 and the uniformity thereof, at the high frequency power fixed to 75W, the pressure to 75 m Torr, and the total flow amount to 30 sccm, along with a variable mixture ratio between Cl 2 and SF 6 . As can be understood from this figure, the etching speed becomes slower as the mixture ratio of Cl 2 is increased as already shown in FIG. 3, whereas the uniformity thereof improves along with increase in the Cl 2 ratio.
To sum up the results of the experiments, it was confirmed that to perform etching achieving a sufficient etching speed for WSi 2 , satisfactory uniformity of the etching speed, and pattern shape, it is important to maintain the mixture ratio of Cl 2 (Cl 2 /Cl 2 +SF 6 ) within 40-70%, keep the pressure at 100 m Torr lower, and appropriately control the high frequency power and the total flow amount. However, as already indicated in FIG. 3, with a small amount of SF 6 added, the etching speed in each of the polycrystal Si and SiO 2 significantly increases. Consequently, if the uniformity of the etching speed in a wafer surface is lowered even in a small degree, since the etching speed is faster in the periphery of the wafer than in the center portion, the SiO 2 film 41 is etched in the periphery area, as shown in FIG. 12B.
Thus, to achieve highly accurate etching of a wafer having the above-mentioned multilayer, the important items are: the substrate should be cooled down to a necessary temperature; the WSi 2 film 43 should be etched by a mixture gas containing SF 6 and Cl 2 ; the polycrystal silicon film 42 should be etched by an etching gas mainly containing Cl 2 gas such as to have a sufficient etching selection ratio with respect to the polycrystal silicon film 42 and SiO 2 film 41 after etching the WSi 2 43.
Next, to examine the etching characteristic of the polycrystal silicon film 42, the etching speed for phosphor-added polycrystal Si, and the uniformity thereof along with a variable high frequency power, were measured. The temperature of the lower substrate was fixed to -30° C. The etching gas used was 100% Cl 2 , and the flow amount thereof was 100 sccm.
FIG. 11 shows the correlations between the etching speed for phosphor-added polycrystal Si and a variable high frequency power, and between the uniformity of the etching speed and a variable high frequency power. In this figure, ◯ denotes the uniformity of an etching speed, and denotes an etching speed. As can be see from the this figure, the etching speed increased as the high frequency power was raised, whereas the uniformity of the etching speed in the wafer surface significantly improved around 90W. Meanwhile, at the high frequency power of 50W, under-cut occurred to the polycrystal silicon, whereas at a powder of 75W or higher, a vertical shape was obtained by etching.
Next, the etching speed for polycrystal Si, and the uniformity of the etching speed along with a variable pressure were measured. FIG. 13 shows the etching speed (denoted by for polycrystal silicon, the uniformity (◯), and the selection ratio (Si/SiO 2 ) (Δ), by use of Cl 2 gas, at the high frequency power 150 fixed to 150W, the substrate temperature to -30° C., the flow amount to 100 sccm, except for a pressure which was variable.
As can be understood from this figure, the etching speed for polycrystal silicon increased as the pressure was raised. The selection ratio between the polycrystal silicon and SiO 2 (heat oxidation film) increased proportionally along with the pressure. On the other hand, the uniformity of the etching speed improved to the peak value around the pressure of 75 m Torr, and when the pressure went away from 75 m Torr to a higher or lower region, the uniformity deteriorated. Then, observation of the etched shape by the SEM indicated that side etching occurred to the pattern when the pressure was higher than 75 m Torr.
Then, in order to improve the uniformity of the etching speed for polycrystal Si, and the selectivity with respect to SiO 2 film, a small amount of various kinds of reactive gas was added to the Cl 2 gas. Thus, the etching characteristic was examined. The etching process was evaluated in terms of the etching speed, uniformity, selection ratios against SiO 2 and resist, and shape of the pattern, and the etching conditions were: the pressure, high frequency power, and gas flow amount were fixed to 75 m Torr, 100W, and 100 sccm, and about 0-10% of oxygen (O 2 ), silicon tetrachloride (SiCl 4 ), nitrogen (N 2 ), and carbon monoxide (CO) were added to the Cl 2 gas.
Table 1 shows the results of this examination. The etching characteristics vary in accordance with pressure, high frequency power, flow amount, and amount of gas add. As is clear from Table 1, a small amount of O 2 added to Cl 2 helped to improve the selection ratio while maintaining the uniformity, and anisotropic shape.
TABLE 1__________________________________________________________________________ Selection ratio against Selection Etching speed Seniformity silicon oxide ratio againstEtching gas Condition (A/nin) (%) film resist layer Shape__________________________________________________________________________Cl.sub.2 50 SCCX 2532 11.6 21.5 3.9 Anisotropy 100 SCCX 2556 10.9 23.7 3.8 "Cl.sub.2 + O.sub.2 95/5 100W 2896 13.2 32.2 3.8 Anisotropy 98/2 100W 2755 13.1 30.3 4.1 Under-cut 95/5,150 W 2622 11.0 16.9 2.6 Anisotrpy 190/10,1150W 4492 10.7 19.0 2.7 "Cl.sub.2 + SiCl.sub.4 90/10 100W 2620 19.8 30.2 4.0 Anisotropy 70/10 100W 2430 15.0 36.8 4.4 "Cl.sub.2 + N.sub.2 90/10 100W 2541 9.1 22.1 4.2 Taper 50/50 100W 1958 4.9 13.0 8.6 "Cl.sub.2 + CO 90/10 100W 2243 12.2 26.0 4.5 Anisotropy 95/5 100W 2483 10.9 22.0 3.6 "__________________________________________________________________________
In this example, the etching step was divided into two, etching of WSi 2 film, and that of polycrystal silicon film, based on the etching characteristics, and a to-be-processed substrate having a multilayered structure of WSi 2 /polycrystal Si/SiO 2 , was etched by use of the device shown in FIG. 1 under the most appropriate etching conditions and with the most suitable etching gas.
First, as can be seen in FIG. 2B, the WSi 2 film 43 was etched. The etching conditions are: the temperature of the lower electrode was fixed to -30° C.; Cl 2 SF 6 mixture gas having the mixture ratio (Cl 2 /Cl 2 +SF 6 ) of 40% was used as the etching gas; and the gas flow amount, pressure, and high frequency power (power density) were set to 30 sccm, 75 m Torr, and 75W (about 0.4W/cm 2 ). Under these conditions, magnetron discharge was induced to perform reactive ion etching until the WSi 2 is completely etched.
Then, supply of the Cl 2 /SF 6 gas was stopped, and the remaining gas was exhausted. While maintaining the temperature of the lower electrode at -30° C., magnetron discharge was carried out using the Cl 2 gas, at the flow amount, pressure, and high frequency power density fixed to 100 sccm, 75 m Torr, and 0.5W/cm 2 , so as to etch the phosphor-added polycrystal silicon film 42. Even after the film appeared to be etched, the etching process was continued for another 20% of the etching time to make sure the film was completely etched.
FIG. 12A shows the results of the etching. As is clear from this figure, no side etching occurred to either the periphery or the center portion of the wafer, or WSi 2 film 34, or the phosphor-added polycrystal silicon film 42, and a vertical shape in cross section was obtained. Further, the underlaying silicon oxide was preserved in good condition without being etched.
As described, in the method of this example, the etching step was divided into two steps, one for the WSi 2 film 43, and another for the polycrystal silicon film 42. In both etching steps, the lower electrode was cooled down to -30° C. In etching of the WSi 2 film 43, a fluorine-containing gas (such as F 2 , or SF 6 ) and Cl 2 gas were used, whereas in etching of the polycrystal silicon film 42, Cl 2 gas, or the same but containing a small amount of O 2 added thereto, was used. Thus, in etching of both WSi 2 and polycrystal Si, a sufficient etching speed, a desired shape, a sufficient uniformity of the etching speed, and a high selectivity between the polycrystal silicon film 42 and SiO 2 film 41 were achieved, and therefore etching of the wafer having the multilayered structure were carried out with an extremely high accuracy, and high reliability.
Consequently, when this method is applied to pattern formation of a gate electrode, a pattern can be formed with a high accuracy and without causing side etching. Further, since the silicon oxide film is never damaged, the gate insulation film can be preserved in a good condition. Therefore, a gate electrode having a high reliability and low resistance can be obtained.
Next, by use of various kinds of etching gas, etching of a tungsten silicide film, polycrystal silicon film, heat oxidation film, and a multilayer including tungsten silicide film/polycrystal silicon film/heat oxidation film, were conducted.
As the etching gas for the tungsten silicide film, a SF 6 /Cl 2 mixture gas was used in the aforementioned example for the following reason. That is, by cooling the lower electrode to -30° C., it is possible to form a vertical shape of the tungsten silicide film by use of solely SF 6 . However, in the case where the etching process was continued for another 20% of the etching time to make sure the tungsten silicide film was completely etched by us of the mentioned gas even after the film appeared to be etched, side etching occurs to the underlaying polycrystal silicon film due to the degree of the unconformity of the etching speed.
In consideration of the above, etching of the tungsten silicide film was carried out by use of solely SF 6 gas, and detection of the end point of the etching was conducted for the purpose of increasing the etching speed, and preventing contamination and waste caused by tungsten silicides having a small vapor pressure. Thus, the time for over-etching was shortened.
The etching conditions were: the high frequency power of 100W, the pressure of 75 m Torr, the lower electrode temperature of -30° C., and the flow amount of SF 6 of 100 sccm.
In the meantime, to find the end point of etching, a spectroscope was used to detect the emission spectrum (wavelength: 468 nm, 466 nm) of the molybdenum fluoride. Thus, the attenuation point of the emission spectrum intensity was monitored, to determine the end point of etching. The etched shape of the tungsten silicide film was actually observed by the SEM, and compared with the attenuation point of the spectrum intensity, and it was confirmed that the end point of etching coincides with the end point measured from the emission spectrum monitored.
Thus, etching was carried out while monitoring emission spectrum to detect the end point of the tungsten silicide film. Then, etching of the underlaying polycrystal silicon was conducted by use of Cl 2 as the etching gas under the conditions that: the high frequency power of 100W, the pressure of 75 m Torr, and the lower electrode temperature of -60° C. Observation of the etched shape indicated no side etching occurred to the tungsten silicide film and polycrystal silicon, and therefore a vertical shape pattern was obtained.
Next, regarding nitrogen trifluoride gas (NF 3 ) and fluorine gas (F 2 ), etching of a wafer having the multilayered structure was performed under the same conditions as that for the above-mentioned SF 6 . Here, observation of the etched shape by the SEM indicated that a vertical shape pattern was obtained in both cases of NF 3 gas and F 2 gas.
Further, similar results were obtained with a mixture gas prepared by adding an appropriate amount of Cl 2 to NF 3 or F 2 , or a mixture gas prepared by adding an appropriate amount of HBr gas to SF 6 , F 2 , or NF 3 .
In the second step of etching the polycrystal silicon, a gas mainly containing Cl 2 gas was used as the etching gas. Here, the emission spectrum of Cl (wavelength: 285 nm) was monitored during etching. As in the case of the tungsten silicide film, the attenuation point of the emission spectrum coincides with the end point of etching, and therefore the end point could be detected at a high reproducibility. To compare with other types of gas, etching of the polycrystal silicon was carried out by use of hydrogen chloride (HCl), hydrogen bromide (HBr), carbon tetrachloride (CCl 4 ) and bromine (Br 2 ).
The etching conditions were set based on the case of Cl 2 gas, namely the pressure of 75 m Torr, the high frequency power of 100W, the flow amount of 100 sccm, and the lower electrode temperature of -30° C., and the conditions are varied for the purpose of each experiment. The results showed that formation of a vertical shape pattern was possible under appropriate conditions by use of these gases. Further, it was also possible to perform successful etching by use of a gas mainly containing fluorine containing gas such as SF 6 , NF 3 , or F 2 , or a mixture gas containing this gas and Cl 2 or Hbr in the first step of etching the tungsten silicide, and a gas mainly containing a fluorine-free halogen gas such as Cl 2 , CCl 4 , or Br 2 in the second step of etching the polycrystal silicon.
Further, by introducing a noble gas such as He, Ar, Kr, or Xe to the above mentioned gas, the uniformity of the etching speed can be improved. Although this experiment was directed to etching of a tungsten silicide, the etching method of this experiment can be applied to a wafer having a multilayered structure of high melting point metal silicides such as tungsten silicide and titanium silicide, or of these metals, polycrystal silicon and silicon oxide film. The temperature of the lower electrode can be varied in the range between -120° C. and 50° C. in accordance with a material to be etched, combination of etching gases, and etching conditions.
The reactive ion etching device used in this example was of the magnetron type having parallel flat plate electrodes. However, the invention is not limited to devices of this type. The type in which a microwave is applied to induce ECR discharge, or the type in which a voltage is applied to a to-be-etched substrate in discharge plasma generated by applying microwave or electron beam can be used. FIGS. 14 and 15 illustrate etching devices which are applicable to the present invention. More specifically, FIG. 14 shows a dry etching device of the plasma etching mode having the structure in which an etching chamber 10 is provided with a gate valve 21 on one side, and a lower electrode 12 on which a not-yet-processed substrate 11 on the lower side, and a high frequency power source 14 is connected to the electrode 12 via a blocking diode 13 so as to supply a high frequency power of 13.56 MHz to the electrode 12. Further, according to this structure, the cooling tube 15 is connected to the lower electrode 12 as in the device shown in FIG. 1, to cool the lower electrode 12 to a predetermined temperature. Above the upper side of the lower electrode 12, provided is an electrode body 52 including an upper electrode 51 such as to face the lower electrode 12. There is some space 53 between the upper electrode 51 and the electrode body 52, and to this space 53, connected is a gas supplying tube 54, through which a reaction gas can be supplied to the space 53 from the outside gas source. The reaction gas supplied to this space 53 can be introduced to the etching chamber 10 through a number of holes 55 formed in the upper electrode 51. A high frequency power source 14 is connected to the upper electrode 51 via a capacitor 13.
In the meantime, FIG. 15 shows a dry etching device of a reactive ion etching mode, having a similar structure to that of the dry etching device, except that a high frequency electrode 14 is connected to a lower electrode 12. Alike elements are labeled with the same numerals as those of FIG. 14, and explanations thereof are omitted.
Each of the devices shown in FIGS. 14 and 15 can be operated following the sam procedure of the device shown in FIG. 1.
Moreover, in the first step, the emission spectrum of tungsten atom was monitored to detect the end point of etching, but it may be the emission spectrum of a tungsten compound such as tungsten fluoride which is monitored. In the second step, the emission spectrum of chlorine was monitored to detect the end point of etching, but it may be the emission spectrum of a silicon compound such as silicon tetrachloride which is monitored. Other than these, the end point of etching may be detected by monitoring change in pressure of the resultant of reaction, or change in plasma impedance.
As described, according to present invention, there is provided a method of processing a film having a multilayered structure including a metal silicide (or high melting point metal) formed on a insulation thin film such as silicon oxide, and polycrystal silicon, which is divided into the first step for etching the metal silicide by use of a gas mainly containing SF 6 , NF 3 , or F 2 , and the second step for etching the polycrystal silicon film by use of a fluorine-free halogen gas such as Cl 2 , while controlling the temperature of the substrate. Therefore, a high-quality pattern formation, where no side etching occurred and the silicon oxide can be preserved in a good condition, can be achieved.
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, and illustrated examples shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
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A dry etching method, wherein a multilayer film including one selected from tungsten, molybdenum, and a silicide thereof, as the first layer, and polycrystal silicon as the second layer underlying is formed on a silicon oxide insulation film, a substrate having a mask pattern on the multilayer film is placed in a vacuum container, an etching gas is introduced into the vacuum container, and an electrical discharge is induced by applying an electrical field to the vacuum container, thereby anisotropically etching the multilayered film in accordance with the mask pattern. The method comprises the first etching step for etching the first layer by use of the first gas selected from fluorine, sulfur hexafluoride, and nitrogen trifuoride, or a mixture gas containing the first gas and the second gas selected from hydrogen chloride, hydrogen bromide, chlorine, bromine, and carbon tetrachloride, as an etching gas, and the second etching step for etching the second layer by use of the second gas, or a mixture gas containing the second gas and the third gas selected from an inert gas, nitrogen gas, oxygen gas, silicon tetrachloride gas and carbon monoxide gas, as an etching gas.
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This is a division of application Ser. No. 425,662, filed Dec. 17, 1973, and now abandoned.
BACKGROUND OF THE INVENTION
The present invention relates to the wet-treating of materials, and more particularly to a novel apparatus for carrying out the wet-treating of materials. There are many instances in which a material must be wet-treated, that is contacted with a treating liquid. For instance, there are materials that must be contacted with a bleaching liquid, there are materials which must be subjected to contact with a liquid for pre-treatment or post-treatment purposes, or materials --such as textile materials --which must be contacted with liquid dyestuff or the like. The present invention is particularly advantageous in the context of the dyeing of textile materials, and will be described with reference thereto, but should be understood to be suitable for all other liquid-treatment applications also.
It is the conventional practice in wet-treating of materials to use liquid media, usually aqueous solutions or dispersions, but sometimes other liquids such as alcohol or halogenated hydrocarbons. In any event, the liquid required, be it water, alcohol, halogenated hydrocarbons or the like, is needed in prodigious quantities and this results both in a wase of resources and --since the spent liquid will eventually be discharged to the environs-- in ecological contamination.
SUMMARY OF THE INVENTION
It is a general object of the present invention to overcome the disadvantages of the prior art.
More particularly, it is an object of the present invention to provide a novel wet-treating apparatus for materials wherein the amount of liquid required for the treating purposes is substantially reduced, thus conserving the particular liquid.
An additional object of the invention is to provide such a novel apparatus wherein, as a result of the reduction in the amount of liquid being used, the amount of liquid discharged to the environs is similarly reduced and ecological contamination is significantly decreased.
Still a further object of the invention is to provide an efficient apparatus for carrying out the operation.
In keeping with the above objects, and with others which will become apparent hereafter, one feature of the invention resides in an apparatus for wet-treating materials, particularly the dyeing of textile materials, which comprises entraining a treating liquid in a stream of gas, and spraying the finely divided treating liquid particles on a material to be treated.
Advantageously, the treating liquid will be as highly concentrated as practicable, being provided in form of a solution or a dispersion. The treating liquid may be a liquid medium based on water or on organic solvents, such as for instance halogenated hydrocarbons.
The stream of gas may be a stream of air, particularly a stream of air which is saturated with water vapor at the operating temperature, or it may be a stream of an inert gas. It is currently preferred that the operation take place at elevated temperature, and that it take place at a static pressure which is higher than the vapor pressure of the liquid medium at the operating temperature.
The operation can be carried out continuously or discontinuously, in the latter case particularly in nozzle-type dyeing machines which are conventionally used for dyeing of textile piece goods.
The most commonly used liquid medium in the prior art, and also according to the present invention, involves a water-based treating liquid, and for this reason the present invention will hereafter be described with reference to a water-based treating liquid and with reference to an operation for dyeing of textiles, as pointed out earlier.
According to the prior art the dyestuffs and any additives that are required --which may be present in form of liquids, pastes or powders-- are dissolved in a liquid or dispersed therein. The various dyestuffs and additives have greatly differing dissolution or dispersion capabilities.
The amount of dyestuff required is determined by the color density that is desired and the weight of the textile material that is to be dyed. As an example, 5% of dyestuff (with reference to the weight of the textile material to be dyed) are needed if the dissolution capability of the dyestuff is for instance 100 g/l of liquid and the textile material weighs 100 kg. This means, in other words, that 5 kg of dyestuff must be dissolved in 50 liters of water, the latter being the minimum amount of water that can be used. This is a ratio of textile weight to water weight of 1 : 0.5.
However, in the apparatus used in the prior art the thus-obtained solution must be further thinned with water in order to obtain a uniform distribution of the dissolved dyestuff over the textile material being treated. In actual fact, a final ratio of textile weight to water weight of 1 : 7 up to 1 : 10 is required in the prior art. The solution having this ratio is pressed through the textile material by means of a circulating pump, and during each pass of the solution through the textile material dyestuff from the solution is yielded up to the textile material, until a condition of equilibrium between dyestuff solution and textile has been reached, or until the dyestuff has been completely withdrawn from the solution and has entered the textile material. In the case of some of the dyestuffs the dyeing operation is carried out at a temperature higher than the boiler temperature of the water, which means that the operation must be undertaken in a closed-circulation apparatus in which the pressure can be so adjusted that an evaporation of the water or whatever other liquid medium is used, is reliably avoided.
Of course, it is well known that with the type of dyestuffs used for textile dyeing, an affinity of dyestuff to textile fiber exists only if the dyestuff is dissolved in a liquid medium. For this reason, the invention also operates with a liquid phase in which the dyestuff is dissolved or dispersed. The invention, however, proposes to use a saturated solution or dispersion which contains only the absolutely necessary minimum amount of liquid. In order to obtain under these circumstances a uniform distribution over and throughout the textile material to be treated, an additional vehicle is required which, according to the present invention, is a stream of gas, usually a stream of air, in which the liquid is entrained. Any suitable means can be provided for spraying the liquid into the airstream and for spraying the entrained liquid via the airstream on and through the textile material.
Since the dyestuffs do not become dissolved in gas, and since therefore the stream of gas can be readily freed of dyestuff residue, and since particularly air is available readily in large quantities, air is usually preferred to produce the stream of gas, but it should be understood that various inert gases can similarly be utilized.
The present invention is advantageously also carried out at temperatures above the boiling point of the liquid medium, as in the prior art. For this reason the pressure existing in the novel apparatus must be high enough so that an evaporation of the liquid medium constituting a part of the dyestuff solution or dispersion, is reliably avoided. Liquid medium is so admitted into the stream of gas that a fine liquid-particle distribution is obtained and that the exceeding of a certain droplet size is avoided. After the gas stream containing the entrained particles has passed through the textile material the residual dyestuff still entrained in it is again removed from it, by means of already known separators.
The novel features which are considered as characteristics 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 drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a diagrammatic illustration showing an apparatus according to the present invention for the discontinuous dyeing of textile material;
FIG. 2 is a digrammatic illustration similar to FIG. 1, but showing an apparatus which is additionally provided with an arrangement for separating residual dyestuff from the entraining airstream;
FIG. 3 is a further diagrammatic view, illustrating an apparatus for the continuous dyeing of textile materials;
FIG. 4 is a view similar to FIG. 3, but illustrating an apparatus which is further provided with an arrangement for separating residual dyestuff from an entraining airstream; and
FIG. 5 illustrates diagrammatically a further apparatus for the continuous dyeing of textile materials.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Before referring in detail to the drawing it should be understood that all Figures show the novel apparatus only in a diagrammatic manner, and that all components which are not essential for an understanding of the invention have been omitted. Thus, valves, devices for producing pressure and the like which are all clearly within the level of skill of those conversant with this art, have not been illustrated.
Referring now to FIG. 1, it will be seen that reference numeral 1 identifies the material to be treated, i.e. in this case textile material. Reference numeral 2 identifies a container into which the textile material 1 is introduced for treating purposes. Reference numeral 3 identifies a blower, reference numeral 4 a heater for heating a stream of gas and entrained liquid particles, reference numeral 5 a vessel which contains a body of dyestuff solution or dispersion, and reference numerals 6 and 7 identify conduits which establish connections between the container 2 and the vessel 5.
The same reference numerals are used in FIG. 2 to identify the same components. In addition, however, reference numeral 8 in FIG. 2 identifies a known separating device 8 wherein liquid is separated from the entraining gas stream, and reference numeral 9 identifies a conduit via which the separated liquid is returned to the vessel 5.
FIG. 3 again shows a container 2 through which, however, the textile material 1 is continuously advanced. Reference numeral 3a identifies seals at the inlet and outlet openings of the container 2. The vessel for the treating liquid is identified with reference numeral 5 and the conduits with reference numerals 6 and 7, respectively. Reference numeral 3 again identifies the blower for circulating the gas stream, and reference numeral 4 the heater.
FIG. 4 is like FIG. 3; identical reference numerals identify identical components. FIG. 4, however, shows additionally the separating device 8 wherein liquid particles are separated from the entraining gas stream, and a conduit 10 via which the separated liquid is returned into a further vessel 11.
FIG. 5, finally, is analogous to FIG. 4, again using identical reference numerals to identify like components. In FIG. 5, however, the vessel 12 which corresponds to the vessel 11 of FIG. 4, is arranged below the container 2.
If the apparatus according to the present invention is to be used for dyeing textile material, the textile material 1 which may be in form of wound bodies, strands, flock, nonwoven material or fleece, is accommodated on appropriate carriers which are known from the art and is introduced into the container 2. The latter and the carrier or carriers for the textile material are provided with arrangements known per se from the art which engage one another so that the carrier can be placed sealingly onto the inlet conduit which enters the container 2. After the textile material 1 is in place, the container 2 is tightly closed.
The requisite quantity of treating liquid is introduced into the vessel 5 and by means of a pressure source which is known from the art the vessel 5, the container 2 and all associated conduits are now subjected to a static pressure whose level is so selected that an evaporation of the liquid treating medium at the operating temperature is avoided. The blower 3 is now energized and the gas under pressure in the interior of the apparatus is circulated, entraining particles of the treating liquid and passing them through the textile material. The heating unit 4 maintains the gas stream at the requisite temperature.
Valves which are diagrammatically shown in the various Figures and are interposed in the conduits 6 and 7 serve to admit controlled quantities of the treating liquid into the gas stream. The conduit 7 is so connected with the gas stream circulating conduit that the gas stream produces an injector effect, i.e. it will cause a suction in the conduit 7 and thus draw treating liquid into the gas stream. The conduit 6 is so arranged that the flow pressure of the gas stream facilitates the outflow of liquid from the container 5. Of course, appropriate pumps or similar devices may be used for admitting dosed quantities of liquid into the gas stream. The circulation of the gas stream with the entrained liquid particles therein can be switched by the use of appropriate control valves or the like, so that the mixture can selectively be passed from outside inwardly through the textile material, or else from inside in direction outwardly through the textile material. The circulation continues until the dyestuff has been yielded up from the liquid to the extent necessary to cause the desired degree of dyeing of the textile material 1.
In addition to this basic operation of the apparatus as described with reference to FIG. 1, the embodiment of FIG. 2 makes it possible --after the stream of gas with its still entrained liquid has passed through the textile material 1-- to separate the entrained liquid from the gas stream by means of the device 8, either wholly or partially, and to return the separated liquid into the vessel 5, either via gravity flow or by the aid of an additional pump which is not shown. The valve in the conduit 7 is used in all embodiments to so arrange the dosing effect that the desired droplet size of liquid in the entraining gas stream is obtained.
The apparatus shown in FIGS. 3 and 4 differ from those in FIGS. 1 and 2 in that here the container 2 is intended for continuous passage of the textile material, rather than for batchwise operation. The textile material here is in form of sheet material, fleece, flock or nonwoven material which can travel continuously through the container 2 from an inlet to an outlet thereof, and for this purpose the container 2 is provided at the inlet and outlet with roller-type or other seals 3a which maintain a sufficient seal so that the selected pressure in the interior of the container 2 will not be lost.
In FIG. 4 there is provided a further vessel 11 into which the separated liquid is admitted. This is desirable to obtain a uniformity in coloring or dyeing depth of the textile material 1. The separated liquid is brought up to the necessary dye concentration in the vessel 11, to assure that there are no fluctuations in the concentration of liquid that is being admitted into the gas stream.
In the embodiment of FIG. 5, finally, the textile material 1 again passes continuously through the container 2. Here, however, the collecting vessel 11 of FIG. 4 is replaced by a similar vessel 12 which is located immediately below and upstream of the container 2, so that the textile material 1 first passes through the vessel 12 in which it becomes uniformly saturated with the treating liquid, to thereupon enter into the container 2 wherein the treating liquid is fixed by means of a hot moist stream of gas, for instance air. In this case, the vessel 5 contains a treating liquid such as water or another suitable liquid which serves to fix the dyestuff, rather than to apply it to the textile material 1 in the first place, since such application takes place as the material passes through the vessel 12.
It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of applications differing from the types described above.
While the invention has been illustrated and described as embodied in the wet-treating of textile materials, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.
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 and, therefore, such adaptions should and are intended to be comprehended within the meaning and range of equivalence of the following claims.
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A treating liquid in form of a preferably highly concentrated solution or dispersion is entrained in a stream of gas, and the thus-entrained finely divided particles of liquid are sprayed against a material to be treated.
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FIELD OF INVENTION
The invention relates to phenol-free, liquid phosphites, based in part on pentaerythritol, which can be used to stabilize organic polymers, especially polyvinyl chloride.
BACKGROUND OF THE INVENTION
Liquid organic phosphites have been used for many years alone and in combination with mixed metal stabilizers for the stabilization of vinyl halide polymers, especially PVC. (Reference: The “Encyclopedia of PVC, Volume 1, L. Nass, Ed., Marcel Dekker Inc., New York, 1977). The phosphite esters employed may be trialkyl, triaryl, mixed alkyl/aryl, and even polymeric.
The problem of imparting polyvinyl chloride with sufficient heat processing stability at temperatures at which the polymer becomes sufficiently fluid or softened to permit shaping is of course of long standing, and has been satisfactorily resolved by the addition to the polymer of various combinations of known heat stabilizers.
At processing temperatures, the PVC resin can degrade, liberating hydrogen chloride, and discolor, become brittle, and stick to the processing equipment. These problems are overcome by combining with the polymer before heat processing or during heat processing one or more of the well established and conventional heat stabilizers, such as, for example, alkyl tin mercaptides or barium/cadmium or barium/zinc or calcium/zinc salt mixed metal stabilizers, aryl, alkyl and mixed aryl/alkyl phosphites, or combinations of the above.
These stabilizers, in preventing the deterioration of the polymers during processing at high temperatures, also permit manufacture of products with increased intrinsic quality because of the enhancement of their resistance to thermal and light degradation during use. In addition, because of the ability of these products to withstand more rigorous conditions, their versatility is increased and new areas of application are thereby opened.
Without going into details or theory, it has been found that mixed alkyl/aryl phosphites such as diphenylisodecyl phosphite and phosphites based on pentaerythritol give the best overall performance in combination with mixed metal stabilizer systems for the stabilization of PVC.
In recent years there has been much concern with exposure to volatiles from the processing of PVC resin, and the exposure to volatiles from articles shaped from stabilized PVC resin exposed to elevated use temperatures. The volatilization of one or more components, or of the decomposition products therefrom, cause the condensation of these volatile components as “fog” on surfaces adjacent to the PVC articles. It has been found that one of the volatiles from the processing of PVC containing certain stabilizers is phenol. The phenol comes from the phosphite used in combination with the mixed metal stabilizer. There is a great need to eliminate or at least minimize the phenol content of phosphite stabilizers and still have a stabilizer which gives good color and processing stability.
One important objection to the contamination of PVC resins with phenol is based on the use of vinyl chloride polymers in food applications, e.g. in the manufacture of food containers. The use of phenol-free stabilizers prevents the transfer of objectionable odors or materials to food.
A preferred phosphite for use with mixed metal stabilizers is diphenyl isodecyl phosphite, but this stabilizer contains about 50% of total phenol. Other phosphite stabilizers based on dialkyl pentaerythritol diphosphites have been known for some time as effective stabilizers for vinyl polymers. Despite wide usage as stabilizers for vinyl chloride polymers, polyolefins, polyurethanes, styrene polymers, and ABS, this type of phosphite has not been entirely satisfactory. The reason for this is the fact that, because of the method of preparation by transesterification from triphenyl phosphite, the dialkyl pentaerythritol diphosphite is contaminated with phenol. In addition, it is advantageous to use mixed metal/phosphite stabilizer combinations as a single liquid component added to the PVC resin during processing. The dialkyl pentaerythritol diphosphites mentioned above are not easily combined with the liquid mixed metal stabilizers, and on standing, a mixture of the liquid mixed metal stabilizer and the dialkyl or diaryl pentaerythritol diphosphite separates into a lighter liquid layer and a more solid layer of heavy sludge. The dialkyl or diary pentaerythritol diphosphite also has a tendency to separate from the PVC matrix on compounding, causing a phenomenon known as plate-out. This lack of package stability and formation of plate-out greatly reduces the usefulness of this type of phosphate.
Pentaerythritol type phosphites and vinyl resins stabilized with such phosphites are disclosed in U.S. Pat. No. 3,281,381 by I. Hechenbleikner and F. C. Lanoue. These pentaerythritol phosphites are prepared by the transesterification of triphenyl phosphite with pentaerythritol to give, depending on the molar ratio of the triphenyl phosphite and pentaerythritol, a variety of possible structures. Tetra-phosphites are made by using 4 moles of the tri (aromatic phosphit), such as triphenyl phosphite for each mole of the pentaerythritol. “Spiro” products, which are diphosphites, are made from the reaction of two moles of the triaryl phosphite with one mole of pentaerythritol. Mixed cyclic and non-cyclic esters are made by the reaction of three moles of the starting phosphite with each mole of pentaerythritol. Although the phenol formed in the transesterification reaction used to produce these materials from triphenylphosphite is removed by distillation during the preparation, the products still contain quantities of free phenol, and phenol bound as a phosphite ester may be liberated during compounding or mixing.
Hechenbleikner, in U.S. Pat. No. 3,205,250 suggests the use of dialkylpentaerythritol diphosphites as stabilizers for polyvinyl chloride. Such dialkyl pentaerythritol diphosphites are prepared according to U.S. Pat. No. 4,206,103 by the reaction of two moles of an alkyl alcohol with a diphenyl- or dichloropentaerythritol diphosphite, made by the reaction of two moles of triphenylphosphite or phosphorous trichloride with one mole of pentaerythritol. When diphenyl pentaerythritol diphosphite is the reactant, the spiro isomer comprises about half the combined total of spiro and caged isomers in the product. The spiro and caged isomers have the following structures:
When dichloropentaerythritol diphosphite is substituted for the diphenyl pentaerythritol diphosphite, the product which results is the relatively pure spiro isomer, which is generally a solid.
The preparation of dialkylpentaerythritol diphosphites which are not contaminated by the presence of phenol is disclosed in U.S. Pat. No. 4,290,976. The process disclosed utilizes the dichloropentaerythritol diphosphite made from phosphorous trichloride and pentaerythritol as a starting material since it does not contain a phenyl group and there is no possibility of phenol being formed as a contaminant. The products of the process described are characterized by higher set points and as a result do not form stable one-phase mixtures with liquid mixed metal stabilizers.
U.S. Pat. No. 3,047,608 describes the preparation of trialkyl phosphites and dialkyl pentaerythritol diphosphites by transesterification from triphenyl phosphite using a dialkyl or diphenyl phosphite as catalyst. The completeness of the transesterification and the removal of the by-product phenol is controlled by the addition of an excess of the higher aliphatic alcohol, and removal of that excess along with the residual phenol by slow co-distillation under vacuum. The use of the diphenyl phosphites as catalysts, however, is inconvenient and expensive, and the product from reaction of pentaerythritol with two moles of triphenyl phosphite and four moles of the higher aliphatic alcohol is mostly in the spiro form, and is incompatible with liquid mixed metal stabilizers.
Accordingly, there remains a need for essentially phenol free pentaerythritol based phosphites which have good compatibility and package stability with mixed metal stabilizers.
BRIEF SUMMARY OF THE INVENTION
One aspect of the present invention is a phosphite useful as a thermal stabilizer in vinyl polymers, especially polyvinyl chloride resin, of very low or nil phenol content which is compatible with liquid mixed metal stabilizers.
It is another aspect of the present invention to provide a phenol-free octaalkylpentaerythritol tetraphosphite, such as octaisododecylpentaerythritol tetraphosphite.
It is yet another aspect of the present invention to provide a stable single phase mixture of a liquid mixed metal stabilizer and an alkyl pentaerythritol phosphite.
Yet another aspect of the invention is to prepare halogen containing vinyl and vinylidene resin composites showing improved resistance to discoloration and plate-out on exposure to the action of heat and processing. Still another aspect of this invention is to prepare stabilized polymers, especially polyolefins, polyurethanes, styrenic polymers, and ABS using the pentaerythritol tetraphosphites.
A still further aspect of the invention relates to a phosphite derived from pentaerythritol, triphenylphosphite, and alkyl alcohols or alkyl phenols, essentially free of phenol, which has excellent package stability with mixed metal stabilizers and confers superior color and thermal stability to PVC, and is useful in the stabilization of other polymers such as polyolefins, polyurethanes, polystyrenes, and ABS.
In one preferred embodiment of the invention the pentaerythritol phosphite is the reaction product of pentaerythritol, triphenylphosphite (or any phosphite based on a lower alkyl alcohol) and a higher alkyl or mixed alkyl alcohols having carbon chains of at least 8 carbon atoms, with the molar ratio of the reactants being about four moles of the triphenyl phosphite and eight moles of the alkyl alcohol to one mole of pentaerythritol.
DETAILED DESCRIPTION OF THE INVENTION
The alkyl pentaerythritol phosphite of the invention is the reaction product of pentaerythritol, triphenylphosphite and a higher alkyl or mixed alkyl or alkaryl alcohols having a at least 8 carbon atoms, straight-chain or branched, up to about 30 carbon atoms. The reaction product is made by the following reaction scheme:
C(CH 2 OH) 4 +4P(OR) 3 +8R 1 OH→({RO} 2 POH 2 C) 4-A C(CH 2 OP{OR 1 } 2 ) A +(8+A)ROH
wherein A generally averages from about 3.5 to about 4.0 based upon a plurality of molecules, and preferably is 4. That is, desirably the phosphite compound does not contain the untransesterified “R” group as found in the P(OR) 3 compound. R is an aliphatic group, a cycloalkyl or alkyl substituted cycloalkyl, an aryl, an aryl substituted alkyl, or an alkyl substituted aryl of from 1 to about 7 carbon atoms, such as phenyl, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, C 5 H 11 , C 6 H 13 , cyclohexyl, C 7 H 15 , or cycloheptyl; R 1 is an aliphatic group of 8 to 20 carbon atoms, straight chain or branched, cycloalkyl or alkyl substituted cycloalkyl of 8 to 20 carbon atoms, aryl substituted alkyl of 8 to 20 carbon atoms, alkyl substituted aryl of 8 to 20 carbon atoms, or combinations thereof. As apparent from the above formulation, preferred phosphite stabilizers are the tetraphosphites containing pentaerythritol groups therein and the same are compatible with various polymers.
In the invention, the mole ratio of pentaerythritol to starting phosphite to higher aliphatic alcohol can vary over a wide range but generally is from about 1-4-6 to about 1-4-10, desirably from about 1-4-7.8 to about 1-4-8.8, and preferably about 1-4-8 to 1-4-8.5.
Examples of P(OR) 3 , the starting phosphite, include trimethyl phosphite, triethyl phosphite, tripropyl phosphite, triisopropyl phosphite, tributyl phosphite, tripentyl phosphite, trihexyl phosphite, and triphenyl phosphite. Examples of the alcohols R 1 OH include all octyl alcohols, all nonyl alcohols, all decyl alcohols, all dodecyl alcohols, all C 12-14 mixed alcohols, all C 12-16 mixed alcohols and blends, and C 8-20 alkyl or C 8-30 alkylaryl alcohols, and C 8-16 alkyl substituted phenols.
The phosphites of the invention can be prepared by the general reaction of the starting phosphite, preferably triphenyl phosphite, with the various alcohols and pentaerythritol, with or without a trace catalyst such as sodium hydroxide. The reaction is heated to a temperature of from about 120° C. to about 170° C. and desirably from about 130° C. to about 150° C. and phenol is distilled off. The reaction is usually completed at a temperature of about 150° C. under a vacuum. The vacuum pulls off the phenol and drives the reaction to completion. Also to remove the residual phenol to the desired (low) level, an excess of the higher aliphatic alcohol is added and the distillation continued, removing the excess along with the residual phenol.
By the term “low residual level” of phenol, it is meant that generally 3% or 2% or less, desirably 1% or 0.75% or less, and preferably 0.5% by weight or less or even nil, phenol remains based upon the weight of the phosphite stabilizer.
When the polymer stabilizer is a halogenated polymer such as PVC, it is very desirable to use liquid mixed metal stabilizers blended with the phosphite stabilizer. A typical liquid stabilizer composition is prepared by mixing an overbased barium nonyl phenate, a liquid zinc carboxylate such as zinc 2-ethylhexanoate, oleic acid, and/or benzoic acid, and a phosphite of this invention. This gives a liquid stabilizer composition containing a mixed metal stabilizer and a phosphite which shows no incompatibility or separation into separate phases on storage.
Mixed metal stabilizers based on typical commercial phenol-free phosphites (such as tridecyl phosphite which contains 6% phosphorous) impart inferior heat stability performance. Mixed metal stabilizers based on typical pentaerythritol diphosphites (such as diisodecyl pentaerythritol diphosphite which contains 0.5 mole of pentaerythritol per mole of phosphorous) are good stabilizers but usually exhibit package instability or phase separation problems. The mixed metal stabilizers which are utilized in this invention are compositions of a neutral zinc carboxylate which is a liquid at ambient temperature, such as zinc octanoate (as opposed to zinc stearate which is a solid), a liquid neutral or overbased barium nonyl phenate (as opposed to a solid barium carboxylate), and small amounts of other additives such as stearic acid or benzoic acid which are soluble in the stabilizer mixture, giving a clear, one-phased mixture.
The amount of the one or more phosphites of the present invention, desirably the noted tetraphosphite when utilized with the halogenated polymers such as polyvinylchloride is generally from about 0.5 to about 5 parts by weight, and desirably from about 1.0 to about 2.5 parts by weight for 100 parts by weight of a halogenated resin. Of course, as noted above, a halogen resin is stabilized, the phosphate is added in a physical blend with the various metal esters or stabilizers noted hereinabove. The phosphite stabilizers of the present invention can also be utilized with other polymers such as polyolefins made from olefin monomers having from 2 or 3 to 6 carbon atoms and thus include polyethylene, polypropylene, polybutadiene, and the like. Other polymers which can be stabilized include the vast number of different types of polyurethanes such as those derived from intermediates containing ethylene oxide, propylene oxide repeat units, i.e. polyesters, or polyester intermediates, which are reacted with various di- or tri-isosyanates including aliphatic, as well as aromatic, and alkyl substituted aromatic di-isosyanates such as methylene di-isosyanate. Another group of polymers include the various styrenic polymers such as polystyrene, poly alpha-methylstyrene, and the like. Still another type of polymer includes the ABS (acrylonitrile-butadiene-styrene) polymers. Other polymers include polyacrylates, polyethers, and the like. The amount of the stabilized phosphites of the present invention with such polymers other than the non-halogenated polymers is from about 0.1 to about 2.5 parts by weight and desirably from about 0.5 to about 1.5 or 2.0 parts by weight for every 100 parts by weight of the polymer.
Stabilized PVC resin compositions are prepared by blending together PVC homopolymer, plasticizer, epoxidized soybean oil, optionally filler and pigment, and the above stabilizer composite of the mixed metal stabilizer and the phosphite of this invention and milling the composition on a 2-roll mill for 5 minutes. The flexible films are sheeted off the mill, cut into strips and tested in a circulating air oven at 200° C. The stabilized PVC composition showed superior resistance to discoloration end an extended time to blackening, indicating superior heat stability of the composition. Stabilized polymers other than PVC are similarly prepared such as by adding the stabilizer to the polymer along with suitable compounding aids such as filler, pigment, and the like and milling the same on a heated roll or otherwise, for a suitable amount of time. Improved properties were once again obtained with regard to resistance to this discoloration and very low amounts of phenol.
We have found that the pentaerythritol phosphite based on 1 mole of pentaerythritol per 4.0 moles of phosphorous, and 8.0 moles plus of isodecyl alcohol gives heat stability performance as good as diphenylisodecyl phosphite which is the industrial standard commonly used phosphite, when used in a mixed metal stabilizer package for PVC. This phosphite is essentially phenol free and gives excellent stabilization, and we found this pentaerythritol phosphite also gives excellent package stability unlike the present commercial pentaerythritol phosphites.
The invention is further described in the following examples, which are included for the purpose of illustration and not for limitation of the scope of the present invention.
EXAMPLES
Example 1.
34.0 g. (0.25 mole) of pentaerythritol, 316.0 g. (2.00 moles) of isodecanol, and 310.0 g. (1.00 mole) of triphenyl phosphite are mixed and heated to 130° C. for 2 hours. After 2 hours, the liberated phenol is stripped off under a slight vacuum. After 2 hours of vacuum stripping, the batch is cooled, yielding 378 g. of clear liquid product as residue in the reaction flask. The distillate was 283 g. (3.0 moles) of phenol containing some isodecyl alcohol.
Example 1 yielded Phosphite 1,i.e. octaisodecylpentaerythritol tetraphosphite.
Example 2.
(comparative example)
158.0g. (1.00 moles) of isodecanol, and 310.0 g. (1.00 moles) of triphenyl phosphite are mixed and heated to 130° C. for 2 hours. After 2 hours the liberated phenol is stripped off under a slight vacuum. After 2 hours of vacuum stripping the batch is cooled. The clear liquid product (374 g.) is obtained as a residue in the reaction flask. The phenol (94 g.) is recovered as the distillate. This phosphite is known as diphenyl isodecyl phosphite.
Example 2 yielded Phosphite 2, i.e. diphenylisodecyl phosphite.
Example 3.
34.0 g. (0.25 mole) of pentaerythritol. 200.0 g. (1.00 moles) of tridecanol, 220.0 g. (1.00 moles) of nonylphenol, and 310.0 (1.00 moles) of triphenyl phosphite are mixed and heated to 130° C. for 2 hours. After 2 hours, the liberated phenol is stripped off under slight vacuum. After 2 hours of stripping, the batch is cooled. The clear liquid product, (374 g.) is obtained in the reaction flask. Phenol (28′3 g.) is recovered in the distillation receiver.
Example 3 yielded Phosphite 3, i.e. a mixture with the average composition of tetratridecyl and tetranonylphenyl pentaerythritol tetraphosphite.
The properties of the above cited phosphites are as follows:
Color,
% Total
Material
% P
CPS/25° C.
APHA
Acid #
Phenol
Ex. 1-Phosphite 1
8.1
24
30
0.1
1.2
Ex. 2-Phosphite 2
8.3
14
50
0.1
50.0
(Control)
Ex. 3-Phosphite 3
5.4
55
20
0.1
Nil
Control-Phosphite 4
6.2
15
<50
0.1
2.0
(Trilsodecyl phosphite)
As apparent from the above data, the stabilized phosphites of the present invention containing pentaerythritol, i.e. Examples 1 and 3 gave very low contents of phenol as in comparison with a Control, i.e. Example 2 which contain diphenyl isodecyl phosphite.
Examples of commercial phosphites that are currently used with mixed metal stabilizers are as follows: (comparative examples)
Color,
% Total
Phosphite Material
% P
CPS/25° C.
APHA
Acid #
Phenol
phenyldiisodecyl
7.1
17
<50
0.05
21
diphenylisodecyl
8.3
14
<50
0.05
˜50
(Phosphite 2)*
diphenyloctyl
9.0
9
<50
0.05
˜54
triisodecyl (Phosphite
6.2
15
<50
0.1
˜20
5)
tris(tridecyl)
4.9
41
<50
0.1
˜2.0
trilauryl
5.3
20
<50
0.1
˜2.0
*This commercial phosphite, diphenylisodecyl, is also phosphite 2 cited in this study, and is used as the standard for comparison of the stabilization performance.
Example 5.
(Testing Example)
Each of the above phosphites (Examples 1 through 4) were evaluated in a flexible PVC resin using the following formulation:
PVC
100
parts
Dioctyl phthalate
38
parts
ESO
2
parts
Stearic Acid
0.2
parts
Phosphite (1-5)
1
part
Mixed Metal Stabilizer*
2
parts
*The mixed metal stabilizer is a 1:1 combination of Barium nonyl phenate (12% Ba) and Zinc 2-ethylhexanoate (12% Zn) (with additional minor components) known as Barostab B-148 from Barlocher USA.
The formulations were blended and milled on a two-roll mill 0.03″ thick at 180° C. for 5 minutes. The films were cut into ½″ strips and tested in a circulating air oven at 195° C. (Werner-Mathis Thermotester). The color of the samples was observed continuously as the strips were withdrawn from the heated zone of the oven and time to discoloration or black was noted.
Testing Results:
Phosphite
% P
% Phenol (1)
Time, minutes (2)
Phosphite 1
8.1
Nil
22.0
Phosphite 2
8.2
0.2
21.5
Phosphite 3
6.4
Nil
20.5
Phosphite 4
6.2
Nil
19.0
(1) % phenol in total PVC formulation.
(2) Minutes elapsed before discoloration.
Compared to Phosphite 2 or isodecyl diphenyl phosphite which is not phenol-free, but currently used widely in the PVC industry, Phosphite 1 of this invention is not only essentially phenol-free but also is an excellent heat and color stabilizer for PVC and has excellent package stability with liquid mixed metal stabilizers.
While in accordance with the patent statutes the best mode and preferred embodiment have been set forth, the scope of the invention is not limited thereto but rather by the scope of the claims.
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Liquid organic phosphites of low volatility, based on pentaerythritol, alkyl alcohols and alkyl phenols, which are essentially phenol-free are disclosed. These phosphites are excellent stabilizers for polymers, especially PVC resins. The phenol-free phosphite stabilizers are compatible with mixed metal stabilizers and give excellent color and processing stability.
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FIELD OF THE INVENTION
[0001] The invention relates to process for the synthesis of β-amino crotonate. Particularly, the invention discloses a continuous flow synthesis for the preparation of β-amino crotonates.
BACKGROUND AND PRIOR ART OF THE INVENTION
[0002] β-amino crotonate are compounds of interest since they find use as intermediates for the synthesis of Ca channel blockers such as Nisoladipine, Benidipine, Nicardipine and such type of compounds, in the preparation and purification of various metals and as a catalyst for polymerization.
[0003] Several batch synthesis processes are disclosed in patent and non patent literature or such types of compounds.
[0004] U.S. Pat. No. 4,046,803 titled “Method Of Preparing β-Amino Derivatives Of α,β-Unsaturated Esters” discloses a method for the preparation of β-amino derivatives of α,β-unsaturated esters of the formula CH 3 C(NH 2 )=CHCOOR′ where R′ is C 1 to C 10 linear or branched alkyl or substituted C 1 to C 10 linear or branched alkyl. A reaction mixture of an acetoacetate ester of the formula CH 3 C(O)CH 2 C(O)OR′ wherein R′ is the same as defined above is first formed in an organic solvent and this mixture reacted with aqueous ammonium hydroxide in the presence of a salt of ammonia or of a metal selected from the group consisting of lithium, zinc, cadmium, cerium and lead. The salt is soluble in the organic solvent to an extent sufficient to catalyze the reaction between ammonia and the ester. The reaction product is readily recovered simply by extracting the solution with a solvent that dissolves the 8-amino a,.8-unsaturated ester. But this process definitely requires the addition of a salt of ammonia or a metal in spite of addition of aqueous ammonium hydroxide, such that salt is soluble in the organic solvent to an extent sufficient to catalyze the reaction between ammonia and the ester.
[0005] U.S. Pat. No. 4,448,964 titled “1,4-Dihydropyridine derivatives” uses a process for preparation of 1,4-Dihydropyridine derivatives described in B. Loev, et al, J. Medicinal Chern., 17, 956 (1974) in Process No. 2 which is reproduce as follows:
[0000]
[0006] The yield in the process is between 20-50%.
[0007] But there is no prior art disclosing a continuous flow synthesis process of β-amino crotonates. Further, there are no prior arts that disclose processes that afford high yield of beta amino crotonates.
[0008] To fulfill this gap in the art, the inventors disclose a continuous flow synthesis, process for β-amino crotonates.
[0009] Further, the invention includes a solvent free catalytic process for the synthesis of β-amino crotonate resulting in pure β-amino crotonate.
SUMMARY OF THE INVENTION
[0010] Accordingly, continuous process for the synthesis of beta aminocrotonates, the process comprising reacting a ketonic ester with a base optionally in presence of an organic solvent and an acid catalyst to obtain the said beta aminocrotonates.
[0011] In an embodiment of the present invention, the ester is methyl aceto acetate or ethyl acetoacetate.
[0012] In another embodiment of the present invention, said base is selected from the group consisting of ammonia, methylamine, ethylamine and tertiary butylamine.
[0013] In yet another embodiment of the present invention, the organic solvent is an alcohol selected from the group consisting of methanol, ethanol or isopropanol.
[0014] In yet another embodiment of the present invention, ratio of said base to said ester is 1:3 to 3:1.
[0015] In yet another embodiment of the present invention, ratio of said base, ester and the solvent is 1:3:0 to 3:1:3.
[0016] In yet another embodiment of the present invention, said catalyst is an aliphatic carboxylic acid selected from acetic acid or n-propanoic acid.
[0017] In yet another embodiment of the present invention, the reaction is performed at a temperature ranging between 20-60° C.
[0018] In yet another embodiment of the present invention, the beta aminocrotonates obtained by the process yields in the range of 93% to 100%.
[0019] In yet another embodiment of the present invention, the representative beta aminocrotonates are methyl amino crotonate, ethyl amino crotonate, tertiary butyl amino crotonate, methyl 3-methyl aminocrotonate, ethyl 3-methyl aminocrotonate, methyl 3-butyl aminocrotonate and butyl 3-ethyl aminocrotonate.
[0020] In yet another embodiment of the present invention, said process is a non-cryogenic process.
[0021] In yet another embodiment of the present invention, the base used is recycled.
[0022] In yet another embodiment of the present invention, an acid is added, such as acetic acid to reduce the reaction time, and is thus used as a catalyst.
[0023] In yet another embodiment of the present invention, process is carried out in a tubular reactor, reducing reaction times but yet yielding products with comparable yields.
[0024] In yet another embodiment of the invention, with reference to FIG. 1 , the process needs continuous supply of only methyl acetoacetate and ammonia to obtain zero water discharge reaction. This reaction is exemplified herein resulting in yield of greater than 90% on repeated cycles.
BRIEF DESCRIPTION OF THE FIGURES
[0025] FIG. 1 : Set-up for zero water discharge continuous process for synthesis of β-amino crotonate requiring continuous supply of only methyl acetoacetate and ammonia.
[0026] FIG. 2 : 1 H NMR of methyl amino crotonate.
DETAILED DESCRIPTION OF THE INVENTION
[0027] In accordance with the objectives of the invention, the inventors disclose a continuous flow synthesis process for β-amino crotonate comprising: reacting a base with an ester in the presence of an organic solvent in ratios ranging from 1:3:0 to 3:1:3 to obtain β-amino crotonate of purity greater than 99.98% and yield greater than 93%.
[0028] Such β-amino crotonates are further reacted with benzilidines to obtain Ca channel blockers.
[0029] The esters used for the process are methyl acetoacetate, ethyl acetoacetate, and such like.
[0030] The base is selected from ammonia, methylamine, ethylamine, tertiary butylamine and such like. The base used is recycled. The process an acid is added, such as acetic acid to reduce the reaction time, and is thus used as a catalyst.
[0031] The solvent of the process is preferably isopropanol.
[0032] The drying time is programmed to result in crystals of β-amino crotonate that required no further purification.
[0033] The process is carried out in a tubular reactor, reducing reaction times but yet yielding products with comparable yields.
[0034] The continuous flow synthesis process of β-amino crotonate of the invention can be carried out in batch mode too.
[0035] Experiments were carried out by mixing methyl acetoacetate with aqueous ammonia (25% solution) at room temperature. Experiment was carried out with and without isopropanol as the solvent media. With the Methyl aceto acetate to ammonia ratio, of 1:1, 1:2 and 1:3 in identical amounts of solvent, the reaction time decreased from 180 min to 75 min with yield of the methyl amino crotonate increasing from 59% to 73%. With the Methyl aceto acetate to ammonia to solvent ratio of 1:2:0, 1:2:1, and 1:2:3, the reaction time for complete conversion of methyl aceto acetate increased from 75 min to 120 min, the yield also increased from 59% to 86%.
[0036] Experiments were also carried out by mixing methyl acetoacetate with aqueous ammonia (25% solution) at different temperatures. With an increase in the batch temperature from 25 degree C. to 50 degree C., the yield decreased from 78% to 52%.
[0037] With reference to FIG. 1 , the process needs continuous supply of only methyl acetoacetate and ammonia to obtain zero water discharge reaction. This reaction is exemplified herein resulting in yield of greater than 90% on repeated cycles.
[0038] The continuous process of the invention is carried out at temperature ranging from room temperature to 50° C., unlike prior art processes that are generally carryout out at cryogenic temperatures to avoid loss of ammonia and to contain exothermic nature of the reaction.
EXAMPLES
[0039] Following examples are given by way of illustration therefore should not be construed to limit the scope of the invention.
Example 1
Process for the Preparation of Methyl Amino Crotonate
[0040] Continuous flow experiment was carried out in a SS316 tubular reactor of 6.35 mm o.d. and 2 m length at 50° C. with a residence time of 15 min. The Methyl aceto acetate to ammonia to solvent iso-propanol ratio was 1:3:1, and the yield of methyl amino crotonate was 56%.
Example 2
Process for the Preparation of Methyl Amino Crotonate
[0041] Continuous flow experiment was carried out in a SS316 tubular reactor of 6.35 mm o.d. and 2 m length at 50° C. in presence of ultrasonic field with a residence time of 15 min. The Methyl aceto acetate to ammonia to solvent ratio was 1:3:0, and the yield of methyl amino crotonate was 54%. No choking of reactor was observed.
Example 3
Process for the Preparation of Methyl Amino Crotonate
[0042] Continuous flow experiment was carried out in a SS316 tubular reactor of 6.35 mm o.d. and 2 m length at 50 C with a residence time of 15 min in the absence of any solvent and without sonication. The Methyl aceto acetate to ammonia ratio of 1:3 resulted in the yield of methyl amino crotonate of 48%. No choking of reactor was observed.
Example 4
Process for the Preparation of Methyl Amino Crotonate
[0043] Continuous flow experiment was carried out in a SS316 tubular reactor of 6.35 mm o.d. and 2 m length at 50° C. with a residence time of 15 min in the absence of any solvent and without sonication. The Methyl aceto acetate to ammonia ratio of 1:2, the yield of methyl amino crotonate observed was 59%. No choking of reactor was observed.
Example 5
Process for the Preparation of Methyl Amino Crotonate
[0044] Continuous flow experiment was carried out in a SS316 tubular reactor of 6.35 mm o.d. and 2 m length at 50° C. with a residence time of 120-160 s without any solvent. The Methyl aceto acetate to ammonia to catalyst (Acetic acid)—volume ratio of 1:3:0.5 yielded 94% methyl amino crotonate from the first crop. No choking of reactor was observed.
Example 6
Process for the Preparation of Methyl Amino Crotonate
[0045] Continuous flow experiment was carried out in a SS316 tubular reactor of 6.35 mm o.d. and 3 m length at 50° C. with a residence time of 120-160 s without any solvent with the inlet composition as in Example 7. The hourly yield of the product methyl amino crotonate was 700 gm. ie. 93% yield.
Example 7
Process for the Preparation of Ethyl Amino Crotonate
[0046] Continuous flow experiment was carried out in a SS316 tubular reactor of 1.58 mm o.d. by mixing ethyl acetoacetate with aqueous ammonia (25% solution) using a simple T-mixer and reactor with 1 m length having a residence time of 22 min. Product yields was 73% at 20° C.
Example 8
Process for the Preparation of Ethyl Amino Crotonate
[0047] Continuous flow experiment was carried out in a SS316 tubular reactor of 1.58 mm o.d. by mixing ethyl acetoacetate with aqueous ammonia (25% solution) in the ration 1:3 using a simple T-mixer and reactor with 1 m length having a residence time of 22 min. Product yields was 84% at 30° C.
Example 9
Process for the Preparation of Ethyl Amino Crotonate
[0048] Continuous flow experiment was carried out in a SS316 tubular reactor of 1.58 mm o.d. by mixing ethyl acetoacetate with aqueous ammonia (25% solution) in the ratio 1:3 using a simple T-mixer and reactor with 1 m length having a residence time of 22 min. Product yields was 94% at 50° C.
Example 10
Process for the Preparation of Methyl 3-methyl Amino Crotonate
[0049] Continuous flow experiment was carried out in a SS316 tubular reactor of 1.58 mm o.d. by mixing methyl acetoacetate with methyl amine in isoproponol in the ratio 1:3 using a simple T-mixer and reactor with 1 m length at 40 C. Complete conversion of the substrates is observed in 30 s. ie 100% yield.
Example 11
[0050] With reference to FIG. 1 , set-up for reaction which needs continuous supply of only methyl acetoacetate and ammonia to obtain zero water discharge reaction is exemplified.
[0051] Methyl acetoacetate (1 mol)=116 gm (Expected yield of the product for 100% conversion =115 gm) when reacted with Aq. Ammonia (2 mol) (MAA:NH3:1:2) and Acetic acid (1 mol) as a catalyst at 50° C. in a tubular reactor for 160 s, it yielded 95.9 gm methyl amino crotonate (86% yield). Filtrate was saturated with gaseous ammonia and was resent to the reactor through a T-mixer with another stream containing only the methyl acetoacetate. Reaction was carried out for reacting 1 mol of the reactant with the ammonia saturated filtrate for all other conditions as mentioned above. The product yield was 101.1 gm (87.8% yield). Upon repeating the filtration, saturation, recycle and reuse of the solution containing acetic acid for the third time and reacted with 1 mol of methyl acetoacetate it yielded 105.8 gm (92% yield) of product. The process thus becomes a zero water discharge process and eventually it achieves a steady state yield of 98%. The maximum loss of acetic acid per recycle was less than 2%. Methyl amino crotonate synthesized by the examples provided herein was characterized by NMR as shown in FIG. 2 . 1 H NMR (400 MHz, CDCl3) showed δ 4.53 (s, 1H,C═CH), 3.64 (s, 3H, CH 3 C═O), 1.91 (s, 3H, CH 3 ). The compound was also characterized by mp and found to be 81.9-82.5 (lit 81-83)
ADVANTAGES OF THE INVENTION
[0052] 1. Continuous process with high yields.
[0053] 2. Non cryogenic process.
[0054] 3. Organic solvent process.
[0055] 4. Zero discharge process with base and catalyst recycled.
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Beta aminocrotonates are important intermediates for the synthesis of Ca channel blockers. The processes available in the art are batch processes with yields about 85%. There are no continuous processes available for the synthesis of such compounds. This gap in the art is addressed by the invention by disclosing a continuous process resulting in high yields of beta amino crotonates.
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CROSS-REFERENCE TO RELATED APPLICATION
This application is a Divisional of U.S. patent application Ser. No. 13/916,744, filed on Jun. 13, 2013, which claims priority under 35 U.S.C. §119 from Japanese Patent Application No. 2012-134319 filed Jun. 14, 2012. The entire contents of both applications are incorporated herein by reference.
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a technique for detecting anomalies in vehicles, industrial machinery, and the like.
Description of the Related Art
Because an accident occurring in industrial machinery at a railway or plant has significant social consequences, it is very important to detect any anomaly that can occur before an accident occurs.
In order to ensure safety, sensors have been installed in vehicles and industrial machinery at various locations to monitor operations, and the measurement data obtained from these sensors has been analyzed by computers to detect anomalies.
For example, the temperature at major locations in a vehicle can be used to detect anomalies. The temperature can be measured using a laser measuring device installed near the path of a vehicle. In this way, early anomaly detection can be performed based on the measured data.
Here, knowledge related to devices used to detect anomalies is incorporated into the computers performing the analysis.
However, anomaly detection in our knowledge base has not yet reached the point of being sufficiently reliable. At this point, the reliability of anomaly detection is being increased by using anomaly patterns detected in the past and reducing the possibility of overlooking cases similar to those in the past. The related technologies described in the following literature are known.
Laid-open Patent Publication No. 7-280603 describes the use of samples in an anomaly detecting method for machinery.
International Patent Publication No. W02008/114863 describes the calculation of the degree of similarity between patterns of change in objects observed using diagnostic equipment.
Laid-open Patent Publication No. 2008-58191 describes the calculation of the degree of similarity between standard parameter values as confidence factors in a diagnostic method for rotating machinery.
Laid-open Patent Publication No. 2009-76056 describes the use of anomaly frequency measurements in a method used to identify anomalous values.
Laid-open Patent Publication No. 2010-78467 describes a method in which a correlation coefficient matrix is created with time-series data for testing purposes and normal time-series data for reference purposes, a sparse accuracy matrix is created in which each correlation coefficient matrix is an inverse matrix, and a localized probability distribution is created for the time-series data for testing purposes and the normal time-series data for reference purposes, preferably using the accuracy matrix in a multivariate Gaussian model.
X. Zhu, Z. Ghahramani, “Semi-Supervised Learning Using Gaussian Fields and Harmonic Functions” in Proceedings of the ICML, 2003 describes semi-supervised learning based on a Gaussian random field model, and discloses labeled data and unlabeled data represented as vertices in a weighted graph.
A. B. Goldberg, X. Zhu, and S. Wright, “Dissimilarity in Graph-Based Semi-Supervised Classification” in AISTATS, 2007 describes a semi-supervised classification algorithm in which learning occurs based on the degree of similarity and dissimilarity between labeled data and unlabeled data.
SUMMARY OF THE INVENTION
Various techniques applicable to anomaly detection have been described, including those with semi-supervised algorithms, but none have suggested the use of anomaly patterns detected in the past. In other words, the effective utilization of anomaly patterns detected in the past requires arbitrary preprocessing in prior art techniques, but this does not sufficiently increase the reliability of anomaly detection.
Therefore, it is an object of the present invention to provide an analytical technique introducing existing label information into an anomaly detection model.
It is another object of the present invention to provide an anomaly detection technique able to effectively utilize label information in data including a mix of both labeled samples and unlabeled samples.
The present invention is intended to solve these problems. The effective utilization of label information is based on the idea of introducing the degree of similarity between samples. This assumes, for example, that there is a degree of similarity between normally labeled samples and no similarity to abnormally labeled samples.
Also, it is assumed that an unlabeled sample has greater a degree of similarity to a normal sample than to an anomalous sample when it has been determined from past experience that a failure is unlikely to occur, and that an unlabeled sample has an equal degree of similarity to a normal sample and to an anomalous sample when there is no previous information.
Each normalized sample is expressed by a multi-dimensional vector in which each element is a sensor value. The present invention also assumes that each sensor value is generated by the linear sum of a latent variable and a coefficient vector specific to each sensor. However, the magnitude of observation noise is formulated to vary according to the label information for the sensor values. The observation noise is set so that normally labeled unlabeled anomalously labeled.
Next, a graph Laplacian is created based on the degree of similarity between samples, the graph Laplacian is used to determine the optimal linear transformation matrix according to the gradient method or the like.
When the optimal linear transformation matrix has been obtained, an anomaly score is calculated for each sensor in the test samples according to the technique described in the Patent Application No. 2011-206087 filed by the present applicant.
The present invention is able to reduce the arbitrariness of criteria for anomaly detection and increase the reliability of anomaly detection by incorporating samples of anomaly patterns and normal patterns detected in the past into an anomaly detection model.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a block diagram showing an example of a computer hardware configuration used to embody the present invention.
FIG. 2 is a block diagram showing a function configuration used to embody the present invention.
FIG. 3 is a flowchart of the process for calculating model parameters for anomaly detection according to the present invention.
FIG. 4 is a flowchart of the process for calculating anomaly scores using model parameters and the like.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The following is an explanation of an example of the present invention with reference to the drawings. The same reference numbers are used to denote the same objects in all of the drawings except where otherwise indicated. The following explanation is a single embodiment of the present invention. The present invention is by no means intended to be limited to the content explained in the example.
FIG. 1 is a block diagram of computer hardware used to realize the system configuration and processing in an example of the present invention. In FIG. 1 , a CPU 104 , main memory (RAM) 106 , a hard disk drive (HDD) 108 , a keyboard 110 , a mouse 112 , and a display 114 are connected to a system bus 102 . The CPU 104 is preferably based on 32-bit or 64-bit architecture, and can be a Pentium® 4, Core® 2 Duo or Xeon® from Intel Corporation, or an Athlon® from Advanced Micro Devices, Inc. The main memory 106 preferably has a capacity of 4 GB or more. The hard disk drive 108 preferably has a capacity of 500 GB or more in order to store a large amount of data.
While not shown in any of the drawings, the hard disk drive 108 includes a pre-installed operating system. The operating system can be any operating system compatible with the CPU 104 . Examples include Windows XP® or Windows® 7 from Microsoft Corporation, or MacOS® from Apple, Inc.
The hard disk drive 108 also contains, as explained below with reference to FIG. 2 , a main program 202 , labeled data 204 , unlabeled data 206 , a parameter group 208 , a graph Laplacian calculation routine 210 , a parameter optimization routine 212 , and an anomaly detection routine 214 . The main program 202 , graph Laplacian calculation routine 210 , parameter optimization routine 212 , and anomaly detection routine 214 can be written in any existing programming language, including Java®, C, C++, or C#.
The keyboard 110 and mouse 112 operate on the operating system or main program 202 loaded from hard disk drive 108 into main memory 106 and displayed on display 114 , and are used to enter characters.
The display 114 is preferably a liquid crystal display. Any resolution can be used, including XGA (resolution: 1024×768) or UXGA (resolution: 1600×1200). While not shown in the drawings, display 114 is used to display operating windows for entering parameters and starting programs, and to display parameter calculation results and the like.
The following is an example of a functional configuration of the processing in the present invention with reference to the block diagram in FIG. 2 .
In FIG. 2 , the main program 202 is a program with functions integrating all of the processing. This is used by the operator to set a parameter group 208 , start the graph Laplacian calculation routine 210 , parameter optimization routine 212 , and anomaly detection routine 214 , execute calculations, and display results on display 114 .
Labeled data 204 includes data detected in the past that has been found to be anomalous or normal. An anomaly label is applied to data found to be anomalous, and a normal label is applied to data found to be normal.
Unlabeled data 206 includes unlabeled data that has not been found to be either anomalous or normal. Depending on the situation, it is treated as either labeled data 204 or unlabeled data 206 .
A single unit of data (called a sample) is a D-dimensional real vector consisting of type-D sensor values. A set of sensor data can be expressed by the equation X=[X1, . . . , XN] T εR N×D , where N is the number of samples.
Sensor data set X is preferably data normalized based on the original sensor data set X′=[X′1, . . . , X′N] T εR N×D . The normalization is performed based on the following equation. Here, Xn,d is the d th element of vector Xn. The same is true of X′n,d.
μ
d
=
1
N
∑
n
=
1
N
X
n
,
d
′
σ
d
=
1
N
∑
n
=
1
N
(
X
n
,
d
′
-
μ
d
)
2
X
n
,
d
=
X
n
,
d
′
-
μ
d
σ
d
Equation
1
Also, label information Y=[Y1, . . . , YN] T εR N×D is provided for each sensordata set X=[X1, . . . , XN] T εR N×D . While not shown in the drawings, this is stored along with the labeled data 204 and the unlabeled data 206 in the hard disk drive 108 .
The label information Y is defined as follows.
Y
n
,
d
=
{
0
if
normal
,
1
if
anomaly
,
NaN
if
unlabel
,
Equation
2
Here, NaN is any real number other than 0 or 1.
In the present invention, it is assumed that each sensor value Xn,d in each normalized sample Xn is expressed as follows with a latent variable ZnεR D′ (D′≦D), coefficients for the magnitude of noise for each label, snormal, sanomaly, sunlabel, and Gaussian noise ε with a mean of 0 and a variance of 1. Here, snormal corresponds to normal, sanomaly corresponds to anomalous, and sunlabel corresponds to unlabeled. Also, D′ is usually equal to D, but D′ is set to about 100 when D is very large and the number of data units N is small.
X
n
,
d
=
{
W
d
T
Z
n
+
s
normal
ε
,
if
Y
n
,
d
=
0
W
d
T
Z
n
+
s
anomaly
ε
,
if
Y
n
,
d
=
1
W
d
T
Z
n
+
s
unlabel
ε
,
otherwise
Equation
3
Here, the setting is snormal≦sunlabel≦sanomaly. Specific examples include snormal=1, sunlabel=3, sanomaly=5 if nothing is found; snormal=1, sunlabel=2, sanomaly=5 if the unlabeled data is found to be mostly normal; and snormal=1, sunlabel=4, sanomaly=5 if the unlabeled data is found to be mostly anomalous.
The parameter group 208 includes parameters such as noise magnitudes snormal, sanomaly, sunlabel, a scale parameter A, and the numbers of dimensions D, D′. These are stored in the hard disk drive 108 , and can be set by the user.
The parameter group 208 also includes values used to determine a similarity matrix R. The similarity matrix is a N x N square matrix, where N is the number of samples, each row and each column correspond to samples (for example, row i/column j corresponds to the degree of similarity between the i th and j th samples), an element corresponding to a normal (labeled) sample and a normal sample is positive number a, an element corresponding to a normal sample and an anomalous sample is non-positive number b, an element corresponding to a normal sample and an unlabeled sample is c, an element corresponding to an anomalous sample and an anomalous sample is d, an element corresponding to an anomalous sample and an unlabeled sample is e, and an element corresponding to an unlabeled sample and an unlabeled sample is f. Here, a, b, c, d, e, and f satisfy the relationships b≦c≦a and e≦d≦f.
Preferably, a, b and d above are set as a=1, b=0, d=0.2.
As in the case of sunlabel, the settings for c, e and f depend on what the algorithm user has discovered regarding the unlabeled data in the application data.
Namely:
c=0.5, e=0.1, f=0.5, for example, if nothing is found;
c=0.8, e=0, f=0.8, for example, if the unlabeled data is found to be mostly normal; and
c=0, e=0.1, f=0.2, for example, if the unlabeled data is found to be mostly anomalous.
The graph Laplacian calculation routine 210 creates a similarity matrix R based on the values a, b, c, d, e, f set in the parameter group 208 , and then calculates a graph Laplacian L from the resulting similarity matrix R in the following way.
K
i
,
i
=
∑
d
=
1
N
R
i
,
d
L
=
K
-
R
Equation
4
The latent variable Z≡[Z1, . . . , ZN] T εR N×D′ is realized by means of the graph Laplacian L as follows.
Pr
(
Z
)
∝
exp
{
-
λ
2
tr
(
Z
T
LZ
)
}
Equation
5
Because the probability Pr(X|W, Z, s) of X≡[X1, . . . , XN] T εR N×D can be regarded as a likelihood function of parameter W≡[W1, . . . , WD] T εR D×D′ and Z, parameter optimization routine 212 seeks (W*, Z*) using, for example, the gradient method so that the posterior probability is optimized. This process will be explained in greater detail below with reference to the flowchart in FIG. 3 .
The anomaly detection routine 214 calculates the anomaly score for each variable based on (W*, Z*) obtained in this manner. The anomaly detection routine 214 preferably uses the technique described in Patent Application No. 2011-206087 filed by the present applicant. The processing in the anomaly detection routine 214 will be explained in greater detail below with reference to the flowchart in FIG. 4 .
The following is an explanation of the processing used to determine the model parameters (optimal linear transformation matrix) W* and the like with reference to the flowchart in FIG. 3 .
In Step 302 of FIG. 3 , main program 202 inputs training data {X′εRN×D,y} by retrieving labeled data 204 and unlabeled data 206 from hard disk drive 108 , normalizes the data in the manner described above, and stores the mean pd and standard deviation ad of each column d calculated when each column was normalized.
In Step 304 , main program 202 retrieves parameter D′, scale parameter λ, snormal, sunlabel, sanomaly, a, b, c, d, e, and f from the parameter group 208 or enters them into a setting screen (not shown) using keyboard 110 and mouse 112 . The scale parameter λcan be set, for example, to 0.1, and the noise magnitude and the like are determined as indicators using the cross-validation method.
In Step 306 , main program 202 calls up the graph Laplacian calculation routine 210 , and a graph Laplacian L is calculated using label information Y and a, b, c, d, e, and f. Because the graph Laplacian L calculation has already been explained with reference to FIG. 2 , further explanation has been omitted here.
In Step 308 , the main program 202 initiates WεR D×D′ and ZεR N×D′ . Any method can be used to perform the initialization. However, W and Z are initialized with a standard normal distribution, that is, a value of each element of W or Z is set to a realized value of a normal distribution in which the mean is 0 and the standard deviation is 1.
In Step 310 , the main program 202 sets the time variable t to 1.
In Step 312 , the main program 202 updates W in accordance with the following equation.
W:=W−α[{S ·( X−ZW T )} T Z+N ( WW t ) −1 W] Equation 6
Here, S is described as follows.
{
S
}
n
,
d
=
{
1
s
normal
if
Y
n
,
d
=
0
1
s
anomaly
if
Y
n
,
d
=
1
1
s
unlabel
otherwise
Equation
7
The operation S·(X−ZW T ) means elements n, d of matrix (X−ZW T ) are multiplied by elements n, d of S. Also, α is the learning rate and is set, for example, to 0.1. The value of α needs not be constant. It can be reduced with each iteration.
In Step 314 , the main program 202 updates Z in accordance with the following equation.
Z:=Z−α[{S ·( X−ZW T )} W+XLZ] Equation 8
This equation is used to perform calculations so that the parameters are updated in accordance with an update equation with a term that reduces the penalty based on the degree of similarity. This includes a term that reduces the penalty based on the degree of similarity to the latent variable of each observation. More specifically, it has been formulated so that the penalty based on the degree of similarity is the Mahalanobis distance based on the similarity matrix (or graph Laplacian). It is then calculated to converge in accordance with the gradient method.
Step 312 and Step S 314 do not have to be calculated in this order. The order can be switched.
After Step 314 , main program 202 , in Step 316 , determines the termination conditions. Here, the Frobenius norm is calculated for the matrix W′ calculated in the previous loop and the matrix W calculated in the current loop, and the termination conditions are satisfied when this is within, for example, 0.001 of a predetermined threshold value.
W
′
-
W
F
=
∑
i
=
1
D
∑
j
=
1
D
′
(
W
i
,
j
′
-
W
i
,
j
)
2
Equation
9
In Step 318 , main routine 202 increases t by “1”, and returns to Step 312 when the termination conditions have not been satisfied.
In Step 320 , main program 202 outputs the model parameters W, snormal, μ=[μ1, . . . , μD], and σ=[σ1, . . . , σD] when the termination conditions have been satisfied.
The following is an explanation of the anomaly score calculation processing performed in anomaly detection routine 214 with reference to the flowchart in FIG. 4 .
In Step 402 of FIG. 4 , main program 202 calls up anomaly detection routine 214 , and provides model parameters W, snormal, μ=[μ1, . . . , μD], σ=[σ1, . . . , σD].
In Step 404 , the anomaly detection routine 214 inputs test data {X′εR N×D , y} by retrieving labeled data 204 and unlabeled data 206 from hard disk drive 108 , X′ in each column is normalized according the equation described above using μ and σ, and X is obtained.
In Step 406 , the anomaly detection routine 214 calculates the correlation anomaly score vector snεR D using the following equation.
s
n
≡
s
0
+
1
2
diag
(
Λ
X
n
X
n
T
Λ
B
-
1
)
Equation
10
Provided,
Λ
=
(
W
T
W
+
s
normal
2
I
)
-
1
B
≡
diag
2
(
Λ
)
(
s
0
)
i
≡
1
2
ln
2
π
Λ
i
,
i
Equation
11
Here, I is a unit matrix. The algorithm used to calculate the correlation anomaly score vector based on the optimal linear transformation matrix W is described in Patent Application No. 2011-206087 filed by the present applicant. It is not described in detail here.
In Step 408 , anomaly detection routine 214 outputs anomaly score vectors s 1 , . . . , sN based on these calculations. Each element of s 1 , . . . , or sN is an anomaly score for each sensor of the first, second, . . . , or N th test sample, that is, each dimension of s=each variable. A higher value indicates an anomaly.
The anomaly detection for industrial machinery at a railway or plant in the present invention was explained with reference to an example. However, the present invention is not limited to this. It can be applied to any example in which anomaly detection is performed based on a plurality of measurement parameters.
|
A method providing an analytical technique introducing label information into an anomaly detection model. The method includes the steps of: inputting measurement data having an anomalous or normal label and measurement data having no label as samples; determining a similarity matrix indicating the relationship between the samples based on the samples; defining a penalty based on the similarity matrix and calculating parameters in accordance with an updating equation having a term reducing the penalty; and calculating a degree of anomaly based on the calculated parameters. The present invention also provides a program and system for detecting an anomaly based on measurement data.
| 6
|
This application is a Continuation-in-Part of application Ser. No. 091,600, filed on Aug. 31, 1987, and now abandoned, which is a Division of Ser. No. 866,876, filed on May 23, 1986, now U.S. Pat. No. 4,693,304, which is a Continuation-in-Part of application Ser. No. 766,648, filed Aug. 19, 1985,
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the use of a specialized horizontal tube heat exchanger operating as either a high rate falling film evaporator, a biological/chemical reactor or a gas-liquid contactor while submerged within a body of heated liquid. Principle applications for the device are (1) a solar still submerged within a salt gradient solar pond; (2) a waste heat evaporator submerged within a hot industrial effluent; (3) a biological/chemical reactor submerged within a temperature controlled liquid heating or cooling medium; and (4) a heat assisted gas stripper. Operating as a solar still, the invention may be used to purify seawater, brackish water, freshwater containing unusually high fouling impurities and for the recycling of irrigation water. Operating as a waste heat evaporator, the apparatus uses hot wastewater as an energy source to purify raw feedwater and to generate heat or vapor for industrial space heating or process uses. As a reactor the present invention has specialized application for reactions requiring careful temperature control, heat recovery, gentle mixing, and prompt removal of gaseous reaction products. As a gas liquid contactor the present invention may be used to separate or strip dissolved gases and volatile organic contaminants from water and other liquids. When used in combination with low boiling point heat transfer fluid and a Rankine cycle turbine generator system, the apparatus may be used to produce electrical power.
2. Description of the Prior Art
The horizontal tube falling film evaporator has been in commercial desalination service since the late 1960s, in the single effect vapor compression mode, and more recently, in the multiple effect configuration using generated steam as an energy source. This evaporator design has also been used in connection with solar ponds and waste heat with the intent to produce power. In order to improve the working quality of the available heat these systems have sometimes utilized low boiling point heat transfer fluids in combination with Rankine cycle turbine generators.
However, in each such case the evaporator consisted of a conventional shell and tube arrangement situated external to the heat laden liquid body. In the recent past, solar ponds have been used to heat water flowing through submerged tubing for space heating purposes without severe corrosion problems.
A rotating disk distillation device is described in U.S. Pat. No. 3,764,483 which operates on the principle of a hydrodynamically applied thin film relying on the wiping action of a flexible blade. A multiple effect version of this device has been proposed for use with a salt gradient solar pond. However, the device was proposed to be situated external to the pond and is not suitable for submerged operation, nor is the evaporation principle the same as the present invention, i.e., wiped film disk versus horizontal tube falling film.
Accordingly, there appears to be no disclosure in the prior art of an evaporator submerged within the heat source, with exposed tube sheets, so as to reduce construction costs, reduce ambient heat loss, eliminate pumping of heating medium, and that rotates to (1) maximize the falling film heat transfer effect, (2) repeatedly expose the concentrate to heat transfer surface, (3) periodically submerge a large proportion of the heat transfer tubes to reduce scaling and (4) induce flowthrough of the heating medium. This combination of features cooperate to maximize the efficiency of the evaporation process while minimizing space requirements compared to the prior art.
The art of producing drinking water from salt water by means of solar distillation is well known. Most designs of solar stills consist of floating or semi-submerged apparatus enclosed by material transparent to solar radiation wherein a pool of salinous water is allowed to heat up and vaporize.
Condensation of the vapor is frequently accomplished by routing the vapor through a deeper level of seawater. Attempts have been made to improve the efficiency of solar energy collection by using lens and solar tracking devices. Examples of prior art are disclosed in U.S. Pat. Nos. 4,325,788, 4,276,122, 4,219,387, 4,172,767, 3,986,936, 3,703,443, 3,408,260, 3,357,898 and 4,151,046.
Systems have heretofore been constructed wherein flat plate solar collectors feed hot water to conventional multistage flash distillation plants. A demonstration scale system of such a system has been in operation in Mexico for several years. Another approach has been to use photovoltaic cells to generate electricity that operates a membrane separation desalination process.
Most of the prior art dealing with solar energy collection ponds, consists of articles published in various trade and scientific journals and, in particular, recent research conducted and published on salt gradient solar ponds by the United States Departments of Interior, Energy and Agriculture. In U.S. Pat. No. 4,110,172 an enclosed solar collection pond is disclosed containing salinous water with a depth of one to ten inches. This invention is focused on the rapid heating of the shallow pool of water and the recirculation of the heated air in order to raise the efficiency of the process.
A ditch similar in configuration to the solar pond utilized in the present invention is described in U.S. Pat. No. 4,141,798. However, the solar still arrangement as described therein is substantially similar in principle to the above mentioned prior art which uses a flexible transparent plastic enclosure operating on a relatively shallow pool of salinous water, i.e., the greenhouse effect.
Applicant is not aware of any prior art which uses a salt gradient solar pond, with its superior temperature elevation capability and heat storage capability in the absence of insolation and/or in the cold season, in combination with a submerged evaporator device specially designed to take advantage of this stored heat in a space much smaller than required by shallow, non-salt gradient ponds, and constructed in such a way as to minimize the consequences of the corrosive environment.
In general, biological or chemical reactions can take place within any form of open or enclosed container. The prior art is replete with reactor configurations where the primary objective is to exercise control of the reaction to most efficiently produce the desired end product. In the biological category, reactors are generally classified as aerobic or anaerobic and suspended growth or fixed film. Most of these reactors are designed for stationary batch or continuous operation wherein nutrient laden liquids flow in and the products of reaction flow out. Solid residues are removed as necessary to maintain optimum efficiency of the process. Temperature control of a biological or chemical reaction may be accomplished by preheating or cooling the influent, by internal electrical heating elements, by heat transfer tubing within the reactor for heating or cooling, or perhaps most frequently by heating or cooling jackets on the periphery of the reactor vessel so as to avoid interference with the requirement for mixing or agitation. The aeration and/or mixing function may be accomplished by external agitation of the reactor vessel, conventional submerged blade mixers, submerged air lifts or diffused bubble aeration. Thus reactions have traditionally been maintained with respect to temperature and mixing by various combinations of the aforementioned techniques within stationary vessels.
In the late l950s fixed film rotating biological contactors were introduced in Europe and later in the United States. This type of reactor is partially submerged within the nutrient laden liquid body and its rotation is designed to allow attached organisms periodic access to both oxygen in the air and nutrients in the liquid. This apparatus consists of open media attached to the rotating support shaft and has no role in temperature regulation of the process. The rotating biological contactor has also been operated in the anaerobic mode by its complete submergence in the nutrient laden liquid body which in turn is contained in a stationary enclosed vessel. Heat is added to the process by any of the aforementioned conventional techniques.
Applicant is not aware of any prior art which uses a reactor consisting of a horizontal tube heat exchanger, submerged within a liquid heating or cooling medium, with exposed tube sheets that rotates to (1) induce flow through of the heating or cooling medium for temperature regulation, (2) periodically expose the reactor liquor to the heat transfer tubing thereby imparting a gentle mixing effect, and (3) create a thin film of liquor on the tubing from which gaseous products of the reaction may more easily separate. The entire reactor vessel embodiment of the present invention thus rotates within the heating or cooling medium, and contains the reaction liquor, rather than being submerged within it, as is the case with the aforementioned rotating biological reactor.
The present invention may be utilized as a gas-liquid contactor by introducing a gas into the heat exchanger module. Gas-liquid contacting is a mass transfer process whereby dissolved gases and volatile organic contaminants (VOC's) are separated from liquid substrates. Heretofore this process has been optimized by maximizing the concentration gradient across the gas liquid interface and by presenting a contacting surface characterized by a thin liquid film and the maximum practical surface area density. The most common device currently in use is the packed bed air stripping tower in which contaminated liquid is introduced at the top and where counter current flow of clean air is introduced at the bottom. The air is removed at the top of the tower and usually sent for destruction of entrained contaminants in an incinerator or catalytic oxidation unit or for capture of contaminants in a gas phase activated carbon filter.
A number of rotating gas-liquid contactors are described in the prior art. The common principle of these devices is to produce extremely thin films, low pressure loss and high volumetric mass transfer coefficients by contacting liquids and vapors in a centrifugal field. In recent years surface area density has been increased by adding packed media to the rotating element. These devices are designed to operate at up to 2000 revolutions per minute.
The present invention represents an improvement over the aforementioned gas-liquid contactors because of its ability to add heat directly to the gas-liquid interface. Increasing the temperature significantly improves the efficiency of the gas separation or volatile contaminant removal process. In the latter case, for example, the efficiency of contaminant removal depends on (1) the air/water ratio applied to the system, (2) Henry's Law constant of the contaminant and (3) the rate of mass transfer. The rate of mass transfer, in turn depends on the contaminant's water diffusion coefficient and the interface area. Increasing temperature positively affects two of these key process variables. Henry's Law constant increases by a factor of two to three for each 10 degrees C rise in temperature, and the water diffusion coefficient of a substance is directly proportional to the absolute temperature K.
The rotation of the present invention is not intended to create a significant centrifugal field as in the case of other rotating gas-liquid contactors. Its rotation generally between 40 and 120 RPM is intended to simultaneously achieve pumping of the heating medium and assured wetting of the contact surfaces which are the horizontal tubes within the heat exchanger. The applicant is not aware of any prior art where heat is introduced directly to the rotating, horizontal tube, gas-liquid contacting surface as in the present invention.
SUMMARY OF THE INVENTION
The present invention may be submerged with a favorable effect within various bodies of liquid that contain quantities of heat that are generally considered in the current industrial practice as of less suitable quality for many desired purposes.
A first preferred embodiment of the present invention combines the unique heat collection and storage capability of the salt gradient solar pond and the superior efficiency of the falling film evaporator in such a way as to minimize construction cost, land requirements, and heat loss to the atmosphere. This embodiment is hereinafter referred to as a high rate solar still.
Compared to other solar energy collection devices, the salt gradient solar pond has the unique capability of maintaining a useful quality and quantity of heat over a sufficient period of time to compensate for diurnal, week long, and even seasonal reductions in insolation. The typical depth of 6 to 10 feet also allows for the collection and storage of solar energy in a smaller space than is the case for other types of solar ponds. Salt gradient solar ponds, in actual practice, have been shown to generate a temperature up to 180 F. during the summer months.
The distillation process (evaporation) has the unique characteristic that the cost of construction and operation, as well as the product water quality, vary insignificantly with the degree of contamination of the feedwater. Hence, the lower the quality of the feedwater, the more economical is the distillation process as compared to other processes capable of removing dissolved inorganics, such as reverse osmosis membranes. Heretofore, the principle drawback to distillation has been the cost of energy to operate the process. The use of solar energy or waste heat, as prescribed herein, avoids this problem.
The high rate solar still of the present invention comprises an evaporator apparatus submerged within a salt gradient solar pond. The pond is preferably long and narrow in configuration in order to reduce the unsupported span and the construction cost of the evaporator support bridge and to allow the use of a factory fabricated impermeable pond liner. This configuration also reduces the risk of wind disturbance since the prevailing wind is usually on the north-south axis and perpendicular to the east-west orientation of the solar pond that maximizes insolation. The depth of the pond is dependent upon the maximum heat storage capability of the pond and the need to provide space for the proper operation of the evaporator. Depending on local conditions, the pond may lie partially below grade or it may be constructed entirely above grade within earthen dikes, or fabricated walls, to facilitate access to piping. In general, the sides of the pond will be sloped at such an angle that entirely earthen construction may be possible without producing shadows during periods of significant insolation.
The evaporator apparatus is submerged within the heat storage section of the salt gradient solar pond. Depending on the pure water production capacity desired, one or more evaporator modules may be placed along the full length of the pond. The evaporator module of the present invention is a form of cylindrical, horizontal tube falling film evaporator in which the tubes, on both ends, allow direct entry and passage therethrough of a salt solution heating medium. The raw feedwater enters the evaporator module through a supporting center shaft, falls through perforations and then from tube to tube, being repeatedly exposed to the heat from heating medium within the tubes.
The entire evaporator module rotates about its horizontal axis at a rate slow enough so as not to disturb the salt gradient but rapidly enough to ensure contact of the falling droplets with many of the tubes within the module. The rotation of the module also serves the purpose of agitating the increasingly concentrated liquid at the bottom of the evaporator module body to improve heat transfer and forming thin films of this liquid as the tubes emerge in their rotation. Flowthrough of the heating medium is induced through the rotation of the apparatus acting in connection with strategically oriented cavitation fins.
The vapor generated by the evaporation process exits at the opposite end of the center shaft and rises through an exit pipe and is directed to a condenser. Thus, the present invention has the effect of converting solar energy into pumping energy. Depending on the location of the point of use and the available head of the feedwater source, this invention may eliminate the need in the process for pumps constructed of costly metal alloys. In contrast, in conventional arrangements, wherein the evaporator is external to the solar pond, it is necessary to pump the saturated salt solution to the evaporator.
Periodically the evaporator must be flushed to remove concentrate. This may be accomplished by directing a large flow of raw feedwater through the evaporator module. The resultant mixture of raw feedwater and concentrate exit the module either up through the exit pipe or down through a drain, if provided. The evaporator module may be brought to the surface of the pond for inspection and maintenance by effecting changes in the buoyancy of the evaporator body in a manner similar to the way submarines remove or add ballast to rise or fall.
Instead of vaporizing raw feedwater, the high rate solar still of the present invention may be used, without significant modification, to vaporize low boiling point heat transfer fluids to be used in connection with a Rankine cycle turbine generator system to produce electrical power. In this case there would be no residue to be removed from the apparatus.
A second preferred embodiment of the present invention, hereinafter referred to as a waste heat evaporator, suspends the evaporator module in a vessel or enclosure through which a liquid heating medium flows, i.e. hot industrial effluent, boiler blowdown or contaminated steam condensate. In this embodiment the module may be rotated at a higher speed. The resulting turbulence will improve heat transfer efficiency due to the dispersal of the thermal layer on both sides of the heat transfer surface. Other benefits are greater velocity of the heating medium being drawn through the tubes and reduced fouling and scaling. Since the vessel or channel may be drained, inspection, cleaning and repair of the apparatus can be accomplished without its removal. The application of the waste heat evaporator embodiment of the present invention may be utilized in the recovery of waste heat from highly contaminated hot industrial effluents in order to produce purified water, space heat, vapor for process use or even electrical power in connection with the use of low boiling point heat transfer fluids. Conventional shell and tube heat exchanger/evaporators are difficult to use in such applications due to increased potential for plugging and fouling.
In essence this embodiment of the present invention facilitates a two stage heat exchange process. The heat is transferred from the hot dirty effluent to the raw feedwater (or heat transfer fluid) which in the form of vapor escapes the module thus preventing the possibility of cross contamination from leaks through either the heat transfer tubing or seal system. When condensed, the vapor rejects its heat in the desired location, for example, for space heating or for preheating boiler feedwater while at the same time producing pure water. Alternately the vapor may be upgraded to higher quality steam for process use by mechanical vapor compression, or in the case of low boiling point heat transfer fluids, used to generate electrical power.
A third preferred embodiment of the present invention utilizes the evaporator module, with certain modification, as a biological/chemical reactor. In this embodiment the module may be supported by attaching the external piping to each tube sheet at the centerline and the internal perforated portion of the center shaft may be removed. This combination heat exchanger/reactor, as before, may be submerged and rotated within a heating (or cooling) medium. Many biological processes benefit from the addition of moderate amounts of heat thereby raising the temperature of the liquor to a level that optimizes the rate of metabolism of the organisms involved. Many endothermic chemical reactions also require the addition of heat. Exothermic reactions, either biological or chemical, generally must be sustained by continuous cooling. The reactor embodiment as described herein promotes rapid heat transfer to or from the reaction, careful temperature control, and affords the capability of heat recovery for economical operation. The movement of the heat transfer tubes through the reaction liquor contained in the partially filled module imparts gentle mixing and agitation while at the same time provides a thin film interface to facilitate the separation of gaseous reaction products. Such gaseous reaction products, if not promptly removed, may inhibit the reaction. The transfer of heat directly to the center of the reactor reduces the energy required for proper dispersal of heat. The module's submergence within the heating or cooling medium reduces the risk of airborne contamination of the reaction by undesirable organisms or gases. Contamination by seal in-leakage may be prevented by circulating the heating or cooling medium through conventional treatment devices such as ultraviolet light sterilizers and/or filters.
A fourth preferred embodiment of the present invention utilizes the evaporator module, modified similarly to the biological/chemical reactor version, to serve as a gas-liquid contactor. The module is submerged and rotated, as before, within a heating medium. In this instance, a gas, usually air, is introduced at one end and flows through the hollow shaft and module counter current to a liquid introduced at the other end. The separation of gas or VOC's from the liquid takes place at the outer surface of the horizontal heat transfer tubes and at the surface of the cylindrical shell within the module. Heat is transferred precisely and directly to the point where it most effectively enhances the stripping process. Thus as the tubes emerge from beneath the liquid level within the module, they perform simultaneously several beneficial process functions; namely, (1) they form uniform thin films which minimizes the diffusional path of the contaminants in the liquid and effectively exposes the liquid to the gas; and (2) they rapidly heat the liquid phase which raises the Henry's Law constant, increases the water diffusion coefficient and creates turbulence in both the liquid and gas phases that improves both heat and mass transfer.
The contaminants transferred to the gas phase may be drawn from the module by an exhaust blower. The heat induced improvement in contaminant removal rate will significantly reduce the volume of gas needed for the stripping process. In the case of air stripping of VOC's the highly enriched air-VOC mixture can be more economically processed in an incinerator or catalytic oxidation device, than can the very dilute mixtures typically produced by packed tower air strippers. The incinerator or catalytic oxidation device, in turn, can be the source of heating medium, usually hot water, for the present invention.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is an elevational view, partially in section, of a preferred embodiment of the invention, schematically depicting the raw water impoundment and the condenser.
FIG. 2 is a top plan view taken along line 2--2 in FIG. 1.
FIG. 3 is an elevational sectional view taken along line 3--3 in FIG. 2.
FIG. 4 is a sectional elevational view of an evaporator module constructed in accordance with the present invention.
FIG. 5 is an end view at the effluent end of a portion of the evaporator module as shown in FIG. 4.
FIG. 6 is a sectional view of the heat transfer tube and cavitation fin, taken along line 6--6 in FIG. 4.
FIG. 7 is a sectional view taken along line 7--7 in FIG. 6.
FIG. 8 is an elevational view of a preferred arrangement for raising and lowering the evaporator module.
FIG. 9 is an elevational view, partially in section, of a second embodiment of the invention.
FIG. 10 is a sectional elevational view of a third embodiment of the invention showing a biological/chemical reactor module.
FIG. 11 is a sectional elevational view of a fourth embodiment of the invention showing a gas-liquid contactor module.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to FIGS. 1-3, a first preferred embodiment of a high rate solar still system in accordance with the present invention is indicated by the reference numeral 10. Solar still system 10 comprises a salt gradient solar pond 12, having a plurality of evaporator modules 14 submerged therein. The solar pond is preferably of a long and narrow configuration to reduce the unsupported span and the construction cost of the bridge structure which supports the evaporator modules. The pond is preferably formed on the bottom by soil and on its sides by earthen dikes 16 and is overlayed with a suitable factory fabricated impermeable pond liner 18. Solar pond 12 is preferably dimensioned as follows: 8 feet to 20 feet in width; 4 feet to 12 feet in depth and may be of unlimited length.
The evaporator modules 14 are supported from support bridges 20, of suitable construction, which span the width of the solar pond 12, such that the evaporator modules are submerged in the heat storage section 22 of the solar pond 12 and oriented parallel to the length thereof. Depending on the pure water production capacity of the system, evaporator modules may be positioned along the full length of solar pond 12. Further, two or more transversely spaced modules may be supported from each bridge structure 20. Alternatively, the evaporator modules may be oriented perpendicular to the length of solar pond 12.
Referring to FIGS. 4 and 5, an evaporator module 14, constructed in accordance with the present invention, is depicted comprising an elongated cylindrical housing 24, sealed off by an influent end plate 26 and an effluent end plate 28. End plates 26 and 28 have a plurality of aligned openings 30 formed therein for receipt of open ended heat transfer tubes 32 therethrough. The respective end portions of heat transfer tubes 32 are suitably sealed to the end plates 26 and 28. A horizontally disposed hollow support shaft 34 extends through horizontally aligned openings 36 in plates 26 and 28 along the horizontal axis of housing 24. Shaft 34 is rigidly secured and sealed to plates 26 and 28 such that rotation thereof effects rotation of the evaporator module 14. The respective ends of shaft 34 are supported for rotation in a suitable manner as by a Teflon bearing and lip seal arrangement 38. The influent end 40 of shaft 34 is connected to a raw feedwater conduit 42 through a suitable fitting 44. Conduit 42 is in communication with a reservoir or source of raw feedwater indicated by the reference numeral 46 in FIG. 1. A control valve 48 is provided to control the flow of raw feedwater through conduit 42.
The entire evaporator module 14 rotates about its horizontal axis and is suitably driven in a conventional manner. For example, a chain and sprocket arrangement 50 secured to shaft 34 may be utilized in cooperation with a motor 52 supported on bridge 20. Alternatively, a hydraulic turbine (not shown) may be utilized to rotate shaft 34 and thereby rotate module 14.
Referring to FIG. 4, shaft 34 is provided with a plurality of openings 54 spaced along substantially the entire length within housing 24. The effluent end portion 56 of shaft 34 is closed off by a wall 58, positioned a short distance inward of end plate 28. Accordingly, all of the raw feedwater directed into shaft 34 through conduit 42 falls through openings 54 into the housing 24. The openings 54 are preferably sized and located in such a manner as to cause the raw feedwater to be distributed along the full length of shaft 34 in approximately uniform flow as the evaporator module 14 rotates about its horizontal axis.
Referring to FIGS. 4-7, heat transfer tubes 32 have influent end sections 60 and effluent end sections 62, which respectively extend outwardly of plates 26 and 28. In order to gently induce the passage of the salt solution medium from solar pond 12 into the influent end portions of tubes 32, the effluent end portions of tubes 32 are provided with cavitation fins 64. Cavitation fins 64 are preferably formed by excising a partial section from the effluent end sections 62, as shown in FIGS. 6 and 7, or, alternatively, by securing a flexible tube sleeve of the same shape. Each cavitation fin 64 is preferably oriented such that an imaginary radial line passing through the apex thereof is always tangent to an imaginary circle that defines the direction of rotation of the corresponding heat transfer tube 32.
The evaporator module 14 is rotated at a rate slow enough so as not to disturb the salt gradient but rapidly enough to ensure contact of the falling droplets passing through openings 54 with many of the tubes 32 within the evaporator module. The rotation also serves the purpose of agitating the increasingly concentrated liquid at the bottom of the evaporator housing 24 and forming thin films of this liquid as the tubes emerge in their rotation. This periodic submergence of some of the tubes also has the effect of reducing fouling and scaling. The optimum level of liquid in housing 24 is suitably controlled to maximize the evaporation process.
The vapor generated during the evaporation process exits the evaporator module 14 through openings 66 in the effluent end portion 56 of shaft 34 downstream from wall 58. The vapor rises up a vertical effluent conduit 68, secured to shaft 34 by a bearing and lip seal arrangement 38 and a fitting 44, and is directed to a heat exchanger/condenser 70, which condenses the vapor into pure product water in a conventional manner. This heat exchanger/condenser 70 may be either air cooled or water cooled. The condensed product water is then directed to its intended use or into a storage tank. The overall efficiency of the process may be improved by using the vapor to heat the incoming raw feedwater.
The evaporator module 14 is preferably constructed of corrosion resistant materials. The module is preferably assembled with gaskets, grommets and fasteners in such a way that it can be disassembled in the field by unskilled labor for the repair and replacement of components and for the removal of scale and foulants.
Periodic flushing of the evaporator module 14 to remove concentrate and to minimize scaling may be accomplished by allowing a large flow of feedwater to enter the evaporator module either from a higher elevation raw water storage impoundment or by pumping. The resultant mixture of raw water and concentrate exits through the openings 66 and is directed up the vertical exit effluent conduit 68, or alternately down a drain conduit 72, as shown in phantom lines in FIG. 4. The flushing operation is controlled by valve 48 and an effluent valve 74 to direct the concentrate to a disposal conduit 76, to prevent the flooding of the heat exchanger/condenser 70 and to prevent untimely drainage. The flushing function may also be accomplished by using the evaporator module in the manner of a compressed air ejector in order to reduce the quantity of wastewater.
Referring to FIG. 8, in accordance with a preferred embodiment of the invention, the evaporator module 14 and interconnected piping may be raised to the surface of the solar pond 12 for inspection and subsequent removal if necessary. First the feedwater valve 48 is closed and continued evaporation will increase the buoyancy of the module. Second, the upper ends of conduits 42 and 68 are released at quick disconnect fittings 77. The submerged module 14 and conduits 42 and 68 are allowed to rise, guided by pipe sleeves 78 secured to the bridge 20. To return the apparatus to its submerged operating position, water is inserted through the open feedwater piping to fill the evaporator body to the extent that it will sink in manner similar to adding ballast to a ship or submarine. When a drain 72 is provided, disconnection is achieved with a quick disconnect coupling 80 and an extended operator rod 82. In this case the small amount of heating medium filling the open drain pipe can be drained into a container and returned to the pond. Alternatively, to facilitate removal of the evaporator from the pond surface the bridge may be raised by virtue of a pin and hinge arrangement (not shown) on one side of the bridge 20.
The evaporator module 14 as described herein may be submerged with a similar effect in any body of heated liquid. Referring to FIG. 9, in accordance with a preferred embodiment of the invention, a waste heat evaporator system is indicated generally by reference numeral 90. The waste heat evaporator system 90 comprises an enclosure or tank 91 having one or more evaporator modules 14 submerged therein. The tank 91 contains a heating liquid or medium 92, for example an available hot industrial effluent, that enters through conduit 93 and exits through conduit 94 at a rate such that a suitable depth is maintained in the tank 91. The evaporator module is supported by a bridge 95 similar to the previously described solar still embodiment 10. The tank may support a removable cover 96 to prevent the escape of vapor from the heating medium into a working area. The cover may be equipped with a duct 97 to recover vapor that flashes from the heating medium. The operation of the waste heat evaporator system 90 is identical to the previously described solar still embodiment 10 where raw feedwater enters through conduit 42 and vapor exits through conduit 68 except that it is no longer necessary to limit the speed of rotation to avoid excessive turbulence in the tank 91, and the module may be more conveniently serviced in place. Further, in addition to the previously stated conventional means to effect rotation, it is possible to drive the rotation of the module 14 by using the head energy of the heating medium entering the tank through conduit 93 against a turbine or water wheel (not shown) affixed to the evaporator module 14. Means is provided to drain the tank to allow inspection, cleaning and repair of the module 14 in place. This consists of a valve 100 on the influent conduit 93 and a drain 101 in the bottom of the tank 91. Because it is not necessary to regularly remove the module 14 from the tank 91, a horizontal extension 98 of feedwater influent conduit 42 and a horizontal extension 99 of conduit 68 may be provided. Concentrate may be flushed from the module 14 in the same manner as previously described for the solar still embodiment 10 with the concentrate exiting the system through conduits 68 and 99 or concentrate drain 102. Alternately the evaporator module 14 may be submerged within a conventional channel (not shown) containing flowing heating medium wherein a downstream flow control device such as a flume or weir, maintains a suitable operating depth.
In either preferred embodiment of the present invention, the high rate solar still depicted in FIGS. 1, 2 and 3 or the waste heat evaporator depicted in FIG. 9, low boiling point heat transfer fluids may be substituted for the raw feedwater to the effect that the resulting vapor may be used to generate electrical power in combination with a Rankine cycle turbine generator system.
In accordance with a further preferred embodiment of the invention, the evaporator module 14 as described herein may be modified by removing a portion of the hollow support shaft 34, so that the module may be utilized as a biological/chemical reactor submerged within a temperature controlled liquid body. Referring to FIG. 10, a preferred embodiment of a biological/chemical reactor in accordance with the present invention is indicated by reference numeral 110. The reactor 110 is submerged within a containment vessel or enclosure (not shown) with connections and supports similar to the waste heat evaporator embodiment 90 and to the solar still embodiment 10. Chemical reactants or nutrient laden substrates enter the reactor through conduit 42 and through the truncated influent end of the hollow support shaft 111. The desired reaction takes place within a liquor filled reservoir 112 within the reactor 110 while said reactor rotates as described in the previous embodiments. The maximum liquid level 113 may be automatically maintained. As fluid enters the reactor through the truncated influent hollow support shaft 111 an equal quantity of fluids, comprised of reaction products and suspended solids, will exit through the effluent hollow support shaft 114 which is affixed to plate 28, and down the drain conduit 72 for further processing. The rotation of the reactor 110 causes each heat transfer tube 32 to periodically enter and exit the liquid reservoir 112 within the reactor 110. The interaction of the tubes 32 and reservoir 112 results in a beneficial agitation and mixing of liquor within the reservoir. As the tubes 32 emerge from the reservoir, thin films of liquor form on the tubes that facilitate the separation of gaseous reaction products from the liquor. These gaseous products and vapors exit the reactor module 110 through the effluent hollow support shaft 114 and through vertical exit conduit 68. The reactor 110 is preferably submerged within an uncontaminated, carefully controlled heating or cooling medium or within the effluent of the reaction process itself which may be recirculated, with makeup heat, through the containment vessel for the purpose of heat recovery. Heat transfer takes place continuously through the reactor shell 24 and the heat transfer tubes 32.
The reactor 110 may be operated in batch or continuous mode. Solids and residues are removed as described in the previous embodiments. As described the reactor module and connecting piping may be strengthened in such a way as to allow its use as a compressed air ejector during the flushing cycle to avoid dilution of the solid residues and to ensure their removal.
One example use for reactor 110 is in the scale up of laboratory fermenters constructed of glass. Glass fermenters have well known advantages including inertness to reactants and observability, but usually give way to polished stainless steel construction in pilot and commercial scale applications. Large glass fermenters would have to be excessively heavy or else be subject to breakage from internal pressure buildup or from external blows, thus allowing escape of possible dangerous reactants. In contrast the reactor embodiment of the present invention, constructed of borosilicate glass, with the possible exception of stainless steel tube sheets, would overcome these limitations to scaleup. Its submergence in a water heating or cooling medium filled tank would obviate the problem of excess weight due to its buoyancy, protect the reactor wall from external blows, and counteract somewhat internal pressure buildup. In-situ sterilization of the contents of the reactor can be easily and quickly achieved by elevating the temperature of the heat medium in which the reactor is submerged.
Another example use of the reactor 110 is in connection with the anaerobic treatment of wastewater. The principal gaseous products of this biological reaction are carbon dioxide and methane. Typical operating problems of conventional technology are difficulty in maintaining temperatures optimal for both the acid and methane forming bacteria, excessive turbulence from high energy mixers that cause foaming and shearing of biological floc, entrapment of gas bubbles in the solids, and the buildup of acids and dissolved carbon dioxide that lowers the PH and inhibits the methane forming bacteria. The reactor 110, with its internal tube array, would ensure the rapid transfer of heat to the reactor center while at the same time imparting a gentle non-foaming mixing action and promote the formation of thin films of liquid that facilitate the separation and release of both the methane and carbon dioxide. The reactor affords the ability, within a single tank system, to rapidly raise and lower the temperature to favor either the acid forming or methane forming bacteria within, for example to limit the buildup of acids that are inhibiting the methane formers.
In accordance with the fourth preferred embodiment of the present invention, the evaporator module, modified similarly to the biological/chemical reactor embodiment described in FIG. 10, may be further modified by adding an additional inlet pipe and utilized as a gas/liquid contactor submerged within a flowing heating medium. Referring to FIG. 11, a preferred embodiment of a gas-liquid contactor in accordance with the present invention is indicated by reference numeral 115. The contactor is submerged within a containment vessel or enclosure (not shown) with connections and supports similar to the waste heat embodiment 90 and to the solar still embodiment 10, except that a new inlet conduit 116 is added. A liquid containing dissolved gases or volatile organic contaminants (VOC) enters the contactor through conduit 116 and through the truncated influent end of the hollow support shaft 111. The stripping gas, such as clean air, enters the contactor through conduit 68 and through the truncated hollow support shaft 114. The contact between gas and liquid takes place on the surface of the heat transfer tubes 32 situated above the maximum liquid level 113 while the contactor rotates as described in the previous embodiments. The maximum liquid level may be automatically maintained.
As fluid enters the contactor through the truncated influent support shaft 111 an equal quantity of the fluid, substantially stripped of dissolved gases, will exit through the effluent hollow support shaft 114 which is affixed to plate 28, and down the drain conduit 72. The maximum level 113 is maintained at a level so as to allow space for the withdrawal of gaseous stripping medium without excessive pressure losses. The rotation of the contactor causes each heat transfer tube 32 to periodically enter and exit the liquid reservoir 112 within the contactor 115. As the tubes emerge from the reservoir, thin films of liquid form on the tubes that facilitates the separation of dissolved gases and VOC's from the liquid. These vapors exit the contactor through the influent support shaft 111 and through conduit 42 for further processing. The contactor is submerged within the heating medium. Heat transfer takes place continuously through the contactor shell 24 and the heat transfer tubes 32. The contactor is operated in a continuous mode. In general there will be no buildup of solids or residues within the contactor 115.
One example use of the gas-liquid contactor 115 is the stripping with clean air of groundwater contaminated with VOC's. Conventional packed towers exhibit problems with proper liquid distribution and adequate wetting of media. The stripping process is inhibited by the low temperature of the groundwater and in winter by the cold stripping air temperature. Tall packed towers require substantial pumping head and produce a very dilute gaseous effluent which is expensive to treat in a catalytic oxidation furnace. In contrast the gas-liquid contactor embodiment of the present invention is a horizontal, low pumping head process, with assured wetting of the contacting surfaces. The addition of heat significantly improves the efficiency of the VOC removal process and produces a highly enriched gaseous effluent that requires much less fuel to destroy in a furnace.
Another example of the use of the gas-liquid contactor 115 would be the stripping of carbon dioxide in a water treatment process. Oxygen could also be stripped from water using an inert gaseous stripping medium such as nitrogen gas.
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An apparatus transfers heat for the purpose of purifying raw feed liquid, separating dissolved gases from liquids, vaporizing heat transfer fluids or containing and regulating biological/chemical reactions. The feed liquid is directed into an evaporator module submerged in a solar pond or other body of heated liquid. The evaporator module includes a rotating housing through which a plurality of spaced apart substantially horizontal open ended heat transfer tubes extend. A heating liquid is directed through the heat transfer tubes. The feedwater is distributed within the evaporator module so as to cause the feedwater to descend into heat transferring contact with the heat transfer tubes and thereby vaporize a portion of the feedwater. A preferred embodiment of the evaporator module is disclosed which includes cavitation fins for urging the heated liquid through the evaporator module.
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This is a continuation of application Ser. No. 07/828,771 filed Jan. 30, 1992, which is a continuation of application Ser. No. 07/439,278, filed Nov. 20, 1989 now U.S. Pat. No. 5,132,600.
BACKGROUND OF THE INVENTION
The invention relates to graphics input devices which are operated manually by a user to provide signals defining a graphical object whose image is to be displayed in a graphics system.
In the prior art, hand-operated pointing or picking devices are known. These devices are operated by a user to position a cursor on the screen of a graphical output device such as a display. The primary role of these devices is to permit a user to select a specific XY location on a display screen. Other devices, called locator devices, include the tablet, the mouse, the trackball, and the joystick. All of these devices are employed to move a screen cursor, and operate in combination with separate devices which input information relevant to the location occupied by the cursor. Most commonly, function buttons, function switches, or alpha-numeric keyboards are used for command or information entry after positioning of a cursor.
In the prior art, the drawing of graphic objects has been the province of a program entered into a graphics processor. Commonly, such an application program utilizes a bottom-up procedure for object creation, using hierarchially-arranged object components. The components map to a set of output primitives with master coordinates which are used to control the function of an output device, such as a display.
Free-hand creation of graphical objects by a user currently is supported by complicated devices having large drawing surfaces upon which the user moves a stylus or pen to draw an image. The drawing surface is related to the display surface by a dedicated applications process which maps the drawing surface to the display area. When the drawing is being made on the drawing surface, a conversion function is invoked, dispatching the application program, and converting the drawing into an image which is displayed on the screen of the display device.
The invention has the objective of providing a user with a graphics input device which permits the display device of a graphics processing system to be used like a drawing surface, without the need to provide a physical surface as an analog to the display surface. This permits a graphics processor system to provide to a user immediate feedback, or echoing, of a drawing operation which the user is conducting. Thus, the display screen of a CRT may be used much as a blank tablet upon which a user can draw.
The integrating graphics input device which has been invented by the applicants provides hand-to-eye feedback through a graphics processor system by combining cursor-like movement of a position area on a display surface, together with tablet-like entry of graphical image information by means of a stylus which can be manipulated by the user to draw within the located positioned area. The device can be used to enter a continuous image by successively relocating the position area in a sequence of overlapping positions within which the user's manual input is integrated to form a continuous, coherent image.
The closest prior art to this device is the inventor's integrating pointing device, described in U.S. Pat. No. 4,719,455 which is incorporated herein by reference. In that device, graphical input was provided by a hand-manipulated device which fit to the user's hand. In the device, gross and fine control of cursor position were generated, respectively, by a moveable cover and a moveable puck contained within the cover.
SUMMARY OF THE INVENTION
The invention is an apparatus for use in a graphics processing system in which a graphics processor responds to graphics input signals descriptive of a graphics object by operating a graphics output device to display an image of the object. The apparatus provides to the graphics processor graphics input signals descriptive of the graphics object. The apparatus includes a manually operable finger grip assembly with a first pressure sensor for providing pressure-generated, force vector signals representing a display location on the graphics output device. A pressure-responsive lockout switch assembly generates a lockout signal. The lockout signal is for indicating inactivation of the force vector signals. In the apparatus, a stylus assembly is moveable in two dimensions and has a position sensor for generating graphics input signals representing a multi-dimensional portion of a graphics object which is to be displayed at the indicated display location. An interface is connected to the finger grip assembly, to the pressure-response switch assembly, and to the stylus assembly for receiving the force vector signals, the lockout signal and the graphics input signals. Last, a processor communicator connected to the interface means communicates to the graphics processor display location signals representing an updated position for the location in response to the force vector signals received by the interface, the lockout signal, and graphic input signals representing the graphic object to be displayed in the updated position.
The principal object of this invention is to provide a graphics input device which integrates graphics input position information and graphics object information which is to be input at the indicated position.
It is the further object of this invention to provide repositioning control of a position area displayed by a graphics processor.
A further objective is to also provide graphics object input signals defining a portion of an image which is to be displayed in the position area.
Other objectives and attendant advantages of this invention will become manifest when the following detailed description is read with reference to the below-described drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an isometric perspective view of the integrating graphics input device.
FIG. 2 is a side-view of the device illustrated in FIG. 1.
FIG. 3 is an exploded assembly diagram of the device of FIG. 1.
FIG. 4 is an elevational side sectional view of the device of FIG. 1, the view being taken along line 175 of FIG. 3.
FIG. 5 is a magnified, side sectional view of a stylus slider in the device of FIG. 1.
FIGS. 6A, 6B, and 6C illustrate the sensors used to provide graphics object force vector, and lockout signals in the device of FIG. 1.
FIG. 7 is a top plan view illustrating a circuit board included in the assembly of the device of FIG. 1.
FIG. 8 is a top plan view illustrating the orientation of certain assembly components with respect to the circuit board.
FIG. 9 is a circuit schematic diagram illustrating the electrical operation of the invention in generating position and graphics object input signals to be input to a graphics processor.
FIG. 10 is a block diagram illustrating the inter-connection of the device with a graphics processor.
FIG. 11 is a detailed schematic diagram illustrating an analog to digital converter of FIG. 10.
FIG. 12 illustrates the response of the graphics processor of FIG. 10 to the signals input by the device of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The integrating graphics input device of the invention is illustrated in external perspective in FIG. 1 and in a slightly magnified side elevation of FIG. 2. The device is indicated by reference numeral 10 and includes a case 11 in which is mounted a finger grip 12, a stylus-like pen 14, and function keys 16 and 17.
The device 10 is a stationary apparatus which a user manipulates by hand to enter position and graphics objects information in the form of hand force and position signals, respectively, into a graphics processor for display. In use, the user grasps the finger grip 12 to change the location of a position area on a graphics processor display. The grip 12 is operated like a stationary joystick to support cursor-like repositioning of the display area.
When the position area is relocated as just described, the user grasps the pen 14 and manipulates it in the X and Y directions to draw in the position area. The pen 14 is free to move in two dimensions, its movements being translated, by means described below, into graphics object input signals which are used by a graphics processor to display the trace of the pen's path in the display area. The pen 14 also permits the operator to enter Z-axis information by varying pressure on the pen 14. The result, for example, would be to vary the width or density of a line being drawn.
The function keys 16 and 17 provide conventional, programmable functions which are selected by the user depressing one or the other of the keys.
The construction details of the device 10 are illustrated in FIGS. 3 and 4. As shown in the Figures, the case 11 is assembled from a carriage 20, which fits to a case top 40. The case top 40 is attached to the case bottom 46; a circuit board 70 is positioned between the case top and the case bottom and attached to the case bottom.
The stylus 14 includes a tip 15 which fits through a boot 19 having a rim 19a. The boot 19 is inserted into a circular opening 21 in the carriage 20, with the rim 19a engaged in an annular groove 21a of the carriage opening. The keys 16 and 17 are mounted to the carriage 20, with the right-hand key 16 received in a quadrilateral recess 22 having a hole 23. The key 16 includes a rod 16a which fits through the hole 23 and a stylus 25. Similarly, the left-hand key 17 has a key rod 17a and is received in a quadrilateral recess 27 of the carriage. The key rod 17a extends through a hole 28 and rod guide 29. The bottom of the rod 17a fits into the stylus 30.
As thus described, the keys are held to the carriage 20 by engagement of the tips of the rod 16a and 17a in the styli 25 and 30. The styli 25 and 30 are received in slots 42 and 43, respectively, and are held therein by retainers 24 and 31.
With the carriage 20 aligned, by way of the slots 42 and 43 with the case top 40, and held to it by the retainers 24 and 31, the opening 20 is aligned with an oval opening 41 in the case top 40. The tip 15 of the stylus 14 extends through the oval opening 41.
A circular opening 45 in the case top receives the upper portion of the finger grip 12. The finger grip 12 is retained against the case top 40 by a grip retainer 50. The annular extension 12a of the finger grip 12 has a larger radius than the hole 45, and is sandwiched between the case top 40 and the retainer 50. The retainer is attached to the case top 40 by screws 53 which are received in threaded bosses 54. The bosses are formed as part of the case top 40; however, for clarity, they are shown detached from the top. A disk lever 52 engages a recess in the shaft of the finger grip 12 and is positioned between the finger grip 12 and the circuit board 70 by a pivot 56 with an annular extension, which fits through a hole 71 in the circuit board. An anchor 57 extends through the bottom of the pivot 56 and contacts the bottom of the disk lever 52, and is retained there by a threaded screw 58 which is screwed into a threaded recess in the center of the disk lever 52.
The pen 14 is retained in an elongate slide 63 which is clamped pivotally between the grip retainer 50 and the case top 40 by one of the threaded screws 53. The tip 15 of the stylus 14 is received in a tip retention recess 67 in the top portion of a rounded slider 66 having two coaxial flanges which slidably engage respective faces of the slotted elongate slide 63. The slider 66 is free to slide in the slot 64 while the pen tip 15 is engaged in the recess 67.
The circuit board 70 has a force sensor 72 in the form of a force sensing resistor upon which the lower edge of the rim of the disk lever 52 rests. Forward of the sensor 72 is a ramped surface 75 on which is held a position sensor 74. A hand pressure sensor 80 is positioned on the bottom of the circuit board 70 and contacted by a button 81 on a threaded foot 82. All of the sensors are attached by adhesive means to the circuit board 70.
The tip of the round slider 66 is illustrated in a magnified cross-section in FIG. 5. FIG. 5 illustrates the connection of the stylus 14 to the slider 66. The stylus is connected to the slider by a spring 89, one end of which receives the tip 15 of the stylus. The spring 89 allows the user to hold the stylus at any desired angle. The round slider 66 is a hollow cylinder in which the other end of the spring 89 is retained in the tip retention recess 67. The spring 89 has a flanged tip extension 90 which is in bayonet engagement with a slider plug 94. The slider plug 94 is moveably held within the slider, so that it can rotate, allowing the user to turn the attached stylus 14 to any desired orientation, and it can also move up and down, in response to upward pressure by a spring 95 and varying downward pressure by the user on stylus 14. As shown, the plug 94 is bored out to contain the tip 15 in an upper bore, as well as a tip 96 which is spring-loaded by the spring 95 in a lower bore. The tip 96 includes a rod which can project into the upper bore of the slider plug 94. The upper end of the tip 96 contacts the lower end of the tip 15 when the spring 95 is compressed by the user pressing down on the stylus 14. When this happens, there is a direct transfer of force from the stylus 14 to the tip 96, as shown in FIG. 5.
FIG. 5 illustrates partial compression of the spring 97 when the tip 15 is pressed with moderate force downwardly toward the slider 66. As illustrated., the pivot of slide 63, together with the slider 66 which moves in the slot 64, enables the tip 96 to move under the force of the pen 14 over the position sensor 74. When assembled, the tip 96 rests on the position sensor. Movement of the pen 14 moves the tip 96 upon the sensor 74, with more or less pressure according to the force exerted against the tip of the pen by the user. Even with no pressure exerted by the user in the stylus, the spring 95 maintains the tip 96 against the sensor 74 with enough force to track the position of the stylus.
The position sensor 74 is illustrated unassembled in FIG. 6A and 6B. As shown, sensor FSR 74 consists of two thin, rigid, plastic sheets 110a and 110b, each carrying a pattern of printed conductive traces and a variable resistance compound. The sheets are identical images, and form the sensor 74 by being assembled with an insulating sheet between them. When assembled, opposite sides of the sheets 110a and 110b face upward. The assembled sensor 74 is illustrated in FIG. 7. As FIG. 7 illustrates, the sheet 110a overlays the sheet 110b, with the center, insulating sheet not illustrated.
The operation of the sensor 74 will now be explained with reference to the sheet 110a, with the understanding that the sheet 110b operates in the same manner. In operation, a regulated DC voltage, V reg , is fed to tap 5 of the sheet, while DC ground is fed to tap 2 of the sheet. The resistive compound forms a L-shaped figure along the left and bottom margins of the array of conductive traces 111a. A continuous voltage drop is induced between 113a where tap 5 intersects the resistive compound and 112a where tap 2 intersects the resistive compound. Thus, at any of the conductive traces which intersect the L-shaped resistive pattern between 113a and 112a, a distinct voltage level can be measured which lies between V reg and ground. Such a voltage provides a positional signal corresponding to a point where pressure is applied in the array 111a. For example, consider that the tip 96 contacts the array 111a at 114, and the user applies a force directed onto the sensor 74 at 114. At 114, the composition of the center insulating sheet causes that sheet to become conductive in response to pressure applied by the stylus in the interstice at 114 between conductive traces 115 and 116. The trace 115 intersects the L-shaped resistor at a point indicated by a respective voltage on the trace 115. Conductivity in the insulating layer at 114 causes current to flow between the trace 115 and the trace 116, thereby bringing the trace 116 to the potential of 115. The conductive trace 116 is one of a plurality of conductive traces which alternate with the traces connected to the L-shaped resistor. These alternating traces are connected in common to a trace 117 which is brought out to a tap labeled "X Pos" (for "X position"). In response to the pressure at 114, the voltage induced on the trace 116 is brought out to the X Pos tap; therefore, the voltage level at this tap conveys precisely the location of the tip 96 when pressure is applied to the pen 14. Further, the amount of current which flows between the conductive strips 115 and 116 is directly related to the amount of force exerted at 114 by the tip 96. Therefore, the current at the tap X Pos indicates the amount of pressure on the pen.
Since the sheets 110a and 110b are stacked, with a separating insulating layer which operates as described above, they operate similarly to produce a pair of position signals which, taken together, correspond to the two dimensional position of the pen 14 with respect to the sensor 74. The second position signal is the Y Pos signal taken from the corresponding tap of the sheet 110b. Together, these signals precisely define the instantaneous location of the pen; a continuous signal chronology of these two taps therefor corresponds to an object drawn on the sensor 74 by the pen.
The regulated voltage V reg is brought also to the taps R Key and L Key to energize the conductive traces on the right and left-hand edges, respectively, of the sheets 110a and 110b. Each of these conductive trace patterns is aligned with a corresponding conductive pattern on a facing surface of the other of the two sheets. When the sheets are assembled as in FIG. 7, the right-hand conductive patterns afford sensor arrangements to detect depression of one of a key. For example, with the assembly shown in FIGS. 2 and 7, the right-hand key 16 is positioned above the conductive trace 120. When the key is depressed, the trace pattern 120 is brought into contact with the conductive block 121, with the result a voltage is provided on the tap R middle.
The hand force sensor is illustrated in FIG. 6C and operates in the same manner as the function key sensors. In this regard, refer also to FIG. 4, where the hand-force sensor 80 is shown positioned on the bottom, rear of the circuit board 70 directly over the button 81. In this position, whenever the user applies pressure on the rear portion of the case top 40, the pressure is transferred through the connecting structure of the case 10 to the case bottom and to the attached circuit board, which causes the hand force sensor 80 to press against the button 81. When this occurs, voltage V reg is conducted to the Hand Force tap of the sensor 80.
In FIG. 7, the translational pressure sensor 72 is illustrated. As with the position sensor 74, the translational pressure sensor 72 comprises two sheets with a pattern of conducting traces and a variable resistance pattern. However, on each sheet, the overall pattern is semi-circular. In FIG. 7, only the conductive and variable resistance patterns of the top sheet 150 are visible, it being understood that the bottom sheet a has similar semi-circular conductive/resistive pattern which is rotated 180° with respect to the pattern on the sheet 150 to form a complete circular pattern. These sheets are also assembled on either side of a center insulating sheet (not shown) which becomes conductive in response to application of pressure. On the sheets 150 and 152, V reg is fed to one of the two taps which connect to the semi-circular resistive trace, such as the trace 153, while the other tap is connected to ground. This provides a continuous voltage drop between V reg and ground from one end of the semi-circular arc to the other. The center tap, tap 155 in the sheet 150 and tap 157 in the sheet 152 provide a voltage corresponding to the location on the continuous resistive circle formed by the two opposing semi-circular conductive patterns on the sheet 150 and 152.
Pressure on the finger grip 12 is transferred to one or the other of the sheets of the sensor 72 through the disc lever 52. A radial A or B Force signal is generated at tap 155 or tap 157 when the material of the center insulating layer becomes conductive in response to the hand grip pressure. The A or B Force signal indicates position along one of the two semicircular patterns and gives pressure at that point. These two components, of course, define a vector whose function is described below.
The sensors 72 and 74 are attached to the circuit board 70 as illustrated in FIG. 7. Signal connection between the sensors and the outside of the device 10 are by a wiring harness 160. The harness includes individual conductors connected, by conventional solderboard means, to the taps of the sensors 72, 74 and 80. In this manner, V REG , common, and ground potentials are connected into the device 10, while the X and Y POS, Right and Left key, Hand Force, and A and B Force signals are conducted from the sensors 72, 74, and 80 out of the device 10.
Referring back to FIG. 1, in the best mode of this invention, conversion and interface electronics are located in an apparatus enclosure 161 and connected to the electronic components of the device 10 by means of the wire harness 160. The wire harness 160 penetrates the device 10 through the case bottom 46 by way of an aperture 47 (FIG. 3). It should be evident, and it is contemplated by the inventors, that all of the circuit functions to be described next can be integrated into monolithic IC form and mounted inside the device 10.
Refer now to FIG. 8 for an understanding of the spatial relationships between the pen assembly and the sensor 74, and the finger grip and the sensor 72. As shown in FIG. 8, when the device 10 is assembled, the circular opening 21 in the carriage 20 is centered in the oval opening 41 of the case top 40. The pivotal connection of the elongate slide 63 and the sliding arrangement between that slide and the round slider 66 permit the tip 96 to be moved by movement of the pen anywhere within the circle defined by the circular opening 21. As FIG. 8 illustrates, this circle is centered in the conductive trace arrays of the sheets making up the sensor 74. In operation, the pen 14 can be moved by the user to draw any kind of a figure within the circle 170, with the time history of the image being available from the X Pos and Y Pos taps on the sensor 74.
The finger grip 12 is aligned with the sensor 72 such that the finger grip assembly, including the disk lever 52, is coaxial with the circular conductivity pattern on sensor 74. As illustrated in FIG. 8, the radius defined by the edge of the disk lever 52 is less than the radius to the circular resistive pattern on the sensor 72. In operation, the finger grip is grasped by the user and force is exerted on it with a component which is radial to the circular conductive pattern of the sensor 72. The radial vector of the force is indicated by the A or B Force signal generated by the sensor 72 in response to the pressure. Thus, if the pressure exerted on the finger grip 12 is toward NNE in FIG. 8, an A Force signal of a particular voltage and current will be generated by the FSR 72 through the tap 155. The magnitude of the voltage is directly related to the direction of the vector, and, therefore, to the direction of the pressure applied to the grip 12. The current is related to the magnitude of the pressure.
Refer now to FIGS. 1, 3, and 8 for an understanding of how the device 10 can be adjusted for the convenience of the user by sliding the carriage 20 either toward or away from the finger grip 12 along the line 175 in FIG. 3. The adjustability is provided to accommodate varying hand dimensions, thereby contributing to the comfort of the user. The carriage 20 slidably engages the case top 40 and can be slid with respect thereto by virtue of the engagement of the case top 40 between the carriage 20 and the retainers 34 and 31 attached to the bottoms of the function key rods 16a and 17a. Three positions are possible: rear, middle, and forward. In the rear position, the carriage 20 is closest to the finger grip 12, and the function keys 16 and 17 are positioned over the lower most conductive traces on the sensor 74. In this position, key signals will be brought out on the tap labeled "R Rear" and "L Rear". When moved to the middle position, the R and L Middle taps provide the function key signals. When the carriage is slid to the position furthest from the finger grip 12, key signals are provided on the R and L FWD taps. In the rear position, ground is provided to tap 3 of both of the conductive sensor portions 110a and 110b. In this position, V reg is provided to tap 4. In the middle position, tap 5 of both sheets is connected to V reg while tap 2 of both sheets is grounded. Last, in the forward position, tap 1 is grounded, while tap 4 receives V reg .
As FIG. 8 shows, reconfiguration of tap voltage connections selects the portion of the conductive traces of the sensor 74 which will be positioned under the circular opening 21 defining the drawing area of the pen 14. Although not illustrated in the drawings, conventional mechanical means are used to lock the carriage 20 in a selected position.
Refer now to FIGS. 9, 10, and 11 for an understanding of the signal conversion and interface circuitry obtained in the electronics enclosure 161 (FIG. 1). FIG. 9 is a schematic diagram which recapitulates the signal path layout discussed above in connection with FIGS. 6A, 6B, 6C, and 7. The V reg , common, and ground signals are generated by conventional means, not illustrated, and conducted initially on signal lines 190 and 191, respectively. These lines connect directly to the sensors 72 and 80, and are connected to the sensor 74 by way of a 4-pole, 3-position switch 218. Common signals are brought into the sensor 72 for A and B Force signals, respectively, on respective signal lines 192 and 193. An X position common signal is conducted on signal line 194 to the switch 218 for provision to the sensor 74. The switch 218 is connected to the taps on the sheets comprising the sensor 74 as illustrated. Signal lines 195 and 196, respectively, conduct signals from the sensor 74 to indicate activation of the right or left keys 16 and 17, respectively. Signal lines 197 and 198 conduct X and Y position signals from the sensor 74. Signal lines 199 and 200 conduct the A and B Force signals from the sensor 72, while signal line 201 conducts the Hand Force signal from the sensor 80. When the carriage 20 is in the forward position, the right and left key 16 and 17 are depressed, causing the conductive patterns 203a and 203b in the sensor 74 to conduct, thereby providing a voltage on the right and left key signal lines 195 and 196. In addition, corresponding signals are diode-connected to the switch 218 to configure it such that V reg on signal line 190 is connected to the tap 4 connections of the sensor 74, while ground is connected to tap 1 on sheet 110b and the X common signal to tap 1 on the sheet 110a.
At the middle position, activation of the function keys connects V reg to tap 5 of both sheets of the sensor 74, ground to tap 2 of sheet 110b, and X common to tap of sheet 110a. Last, in the rear position, the function keys operate the switch 218 to connect V reg to tap 6 on sheets 110a and 110b, ground to tap 3 of sheet 110b, and X common to tap 3 of sheet 110a. The sensors 72, 74 and 125 operate as described above to provide the Hand Force, A and B, and X and Y position signals on signal lines 201, 200, 199, 198, and 197, respectively.
FIG. 10 illustrates the means for integrating the integrating graphics input device 10 with a graphics display processor. In FIG. 10, the graphics display processor includes a processing unit with a graphics display 240 which interfaces with the electronics unit 161. The interface between the electronics unit and the device 10 has already been explained above with reference to FIGS. 6A-6C and 9. The primary components in the electronics unit 161 include a circuit 250 for analog-to-digital conversion (ADC) and a microprocessor 255. Essentially, the ADC 250 receives and converts the level signals described above to digital signals, formats the digital signals and provides them to the microprocessor 255. The microprocessor 255 receives the formatted digital signals and conducts a communication process with the processing unit 240 for transfer of those signals to the processing unit for incorporation into a graphics processing application.
Refer now to FIG. 11 for a more detailed illustration of the ADC circuit 250. In FIG. 11, the signal paths 194-199 all correspond to identically-numbered signal paths in FIG. 9. All of these signals are fed to respective input ports of a conventional analog-to-digital converter (ADC) 260. The converter receives a reference voltage for conversion from a reference voltage circuit 261. In addition, the ADC 260 receives the X position signal through a buffer 262, the pen force signal through a buffer 263, and the Y position signal through a buffer 264. The buffers 262 and 263 are both connected, through respective switches 266 and 267 to the signal line 197, which is also connected to a switch 268 The signal line 194 is also connected to the switch 268. The switches 266, 267, and 268 are configured by respective control signals XPOS, XFORCE, and XSEL which are provided from the microprocessor 255. These signals are conventional control signals which condition the switches 266, 267 and 268 to on or off conditions. These signals are provided to multiplex the X Pos signals on signal line 197 to provide both X position information relating to the X position of the pen with respect to the sensor 74, and also to provide the pen pressure signal. For the X position signal, the switches 267 and 268 are conditioned to their OFF states, while the switch 266 is conditioned ON. In this case, the X Pos signal is fed to the buffer 262 for buffering to the ADC 260. In this state, X Pos Common line 194 is grounded to provide a reference for the X Pos signal. Next, the control signals condition the switches 267 and 268 ON and turn OFF the switch 266. In this state, the resistor R 3 converts the current input on the signal lead 197 to a voltage signal proportional to the current level, and thus, to the force with which the pen 14 contacts the FSR 74. This signal is buffered to the ADC 260 through the buffer 263.
The Y Pos signal on signal line 198 is fed continuously through the buffer 264 to the ADC 260. The Hand Force signals and the left and right key signals are fed directly, without buffering, to the ADC 260.
The A and B FORCE signals are buffered and multiplexed in a circuit 272. The circuit 272 includes respective buffering sections for the A and B FORCE signals which operate as described above for the X Pos signal to obtain both position and magnitude signals which correspond to the position of the grip 12 with respect to the sensor 72 and to the pressure with which the grip contacts the sensor. The buffers operate in response to the ground, A and B common (COMM), and A/B POS, A/B FORCE, and A/B SEL signals as do the buffers 262 and 263. In addition, the A/B SEL signals operate to multiplex the outputs of the A and B buffers to input pins 12 and 13 of the ADC 260. Thus, for example, when the A buffer is configured to sense position (voltage), the buffer (not shown) which corresponds to buffer 262 is connected to pin 12; when the A buffer senses pressure (current), the buffer (not shown) corresponding to buffer 263 is connected to 12.
The ADC 260 receives a divided clock by way of a conventionally-configured flip-flop 271, reference voltage signals from ground and from the generator 261, and control signals from the microprocessor 255 to conventionally convert the level signals present at its input (I) pins to digital words representative of the converted levels at the output (D) pins. The output (D) pins of the ADC 260 are connected to an address/databus which shares, with the output pins, common connections with three address (A) pins of the ADC 260. In operation, the microprocessor 255 conventionally controls the ADC with FETCH -- DATA, CONVERT, LOAD -- ADDR, and RESET control signals. These signals are conventional and operate the ADC 260 to sequentially address input pins, sample the voltage at the currently-addressed input pin, and output a digital word corresponding to the level of the voltage sampled at the currently-addressed input pin. The address is then changed to the next input pin, and so on. In synchronism with the sampling sequence, the microprocessor 255 configures the switches 266, 267, and 268 to ensure that, for example, when pin 10 is addressed, the X Pos voltage signal is buffered through the buffer 262. Similarly, when the input pin Il is addressed, the switches 266, 267, and 268 are configured to provide the pen pressure current through the current buffer 263.
Further, when A or B FORCE signals are being sensed, the ADC 260 is similarly addressed and controlled, in synchronism with the multiplexing of the circuit 272, to sample and convert A position and A force magnitude signals through pin 12, and B position and B force magnitude signals through pin 13.
Refer now to FIG. 11 and to Tables I-IV for an understanding of how the operation of the ADC 260 is controlled to convert the signals produced by the FSR's 72, 74, and 80. In Table I, a series of functions and global variables are defined. Then, in a main loop, the converter 260 is interrogated in a sequence of calls to 3 subroutines: ADCSTB, ADCSTAT, and ADCDATA (Tables II, III, and IV, respectively).
Interwoven with the call sequence of Table I is a control sequence for conditioning the three switches 266, 267 and 268 for reading either X Pos or the pen downforce signal output by the sensor 74. The control sequence also conditions the A/B POS, -FORCE, and -SEL signals to read A position, A magnitude, B position, and B magnitude signals output by the sensor 72.
Initially, a main loop is defined in step 116, conditions are initialized in steps 117-119, and in step 120, the XPOS, APOS and BPOS signals are energized. Activation of XPOS to turn ON the switch 266. Concurrently, the switch 268 is OFF grounding the XPOS Common line 194, which provides a ground potential against which the X position information is measured by the buffer 263. The control signals are hexadecimal (H) signals which are output through microprocessor port 58H. The A and B POS signals similarly configure the buffer sections of circuit 272.
Next, a loop index (i) is defined, initialized to zero, limited to the range of whole numbers between 0 and 10 and incremented by 1 for each step of a looped sequence beginning at line 124 of Table I. A byte-wide 10-position buffer is initialized in step 124 and then an endless loop entered in steps 125 and 126. In steps 127-130, the X position of the pen 14 is obtained by conversion of the X Pos signal on the path 267, 263, 260 in FIG. 11. First, the ADCSTB macro (Table II) is called. This macro provides an address (ADDRESS 0 in line 128) on the address databus connected to the ADC 260, a LOAD -- ADDR control signal to the ADC 260 notifying it to load the address on the address/databus, and then a CONVERT (ADC STROBE) control signal commanding the ADC 260 to begin its procedure of converting the level of the signal on the input port addressed on the address/databus. The addressed input port is I0, connected to the buffer 262. Therefore, the X Pos signal is converted to digital format by the ADC 260.
The ADC 260 operates conventionally to provide an end of conversion (EOC signal) which sets a status flip-flop 270. This conditions an ADC -- STATUS signal to an ON state. When the ADC -- STATUS signal is conditioned ON, the ADC DATA macro (Table IV) is dispatched, which reads the converted data off of the address/databus, and resets the status flip-flop 270 via the RESET signal. The data which is converted from the signal input at ADC 10 is entered into location {0} in the buffer.
Following conversion and buffering of the X PPS signal, a hexidecimal code `80` is provided through processor port 58H, which turns OFF switch 266, while turning 268 ON. This "floats" the signal line 174, while pulling down the signal line 197 through the parallel resistances R2 and R3.
Next, in steps 135-143, the A and B position signals are sampled in the same manner as the X position signal, and placed in buffer locations 3 and 4. The ASEL and BSEL signals are not active, which appropriately connects the buffered versions of the position signals to the ADC 260 through the multiplexing section of the circuit 272. Then, in step 144, the APOS and BPOS signals are deactivated while the ASEL and BSEL signals are activated.
Then, in steps 145-148, the Y position buffer 264 is addressed via the ADC 260, the Y position signal is converted and sent to buffer location 1. The A and B FORCE signals are activated in step 149. Next, in steps 150-153, the Hand Force signal on signal line 199 is converted and placed in buffer location 5.
By the time the program in Table I reaches steps 150-153, the switches 266, 267, and 268 have been turned OFF, ON, and ON, respectively, in enough time to damp out any switch bounce. Now, in steps 154-157, the pen downforce signal is provided through the buffer 263, converted, and stored in buffer location 2. In program line 158, all of the switches 266, 267, and 268 are turned OFF, while the ASEL, BSEL, A FORCE, and B FORCE signals are activated. Then, A FORCE, B FORCE and left button signals are converted in steps 159-171. In step 171a, the XPOS signal is activated together with the APOS and BPOS signals, turning ON the switch 266, and preparing the buffer 262 for X Pos, A Pos, and B Pos conversion. Following this, the right button status is converted and stored in buffer location 7 in program steps 172-176. The program loops, at step 177 back to step 125.
Reference is now made to lines 129, 138, 142, 150, 154, 162, 166, and 174 of Table I, all of which call a TESTXMIT subroutine. The TESTXMIT subroutine is called and executed while the ADC is conducting a conversion process. Thus, until the ADC -- STATUS bit is set, Table I executes the TESTXMIT subroutine. The TESTXMIT subroutine polls the host graphics processing unit 240 for a communications initiation handshake signal. When it detects a "start" handshake signal from the host, it transmits 10 bytes of data by transferring the contents of the 10-position buffer which is loaded as described above to a transmit buffer (XMITBUF). Transmission is based upon availability of the transmit buffer, which is determined by availability of a serial I/O channel. The availability is tested in steps 183 and 185. If available, the subroutine SENDSTR is invoked to transmit a string of 10 bytes from the transmit buffer through a serial I/O port to the graphics processing unit 240.
The reaction of the graphics processing unit 240 to the position, hand force and function key signals generated by the device 10 and converted through electronics 161 is illustrated in FIG. 12.
As FIG. 12 illustrates, the graphics processing unit 240 operates a conventional display 275 which may comprise a CRT. The graphics processing unit 240 includes a dispatchable graphic input device handler (not shown) which receives the converted signals from the electronics 161, and passes them to a graphics processor (now shown) for driving a display. The user of the device 10 is enabled by the graphics processing unit 240 to observe a drawing being made on the display 275 by means of the input device 10. In this regard, the graphics processing unit 240 provides a defined position area showing the user where, on the image being displayed, the drawing input from use of the pen is being entered. In FIG. 12, this area is displayed as a circle 280, corresponding to the circle 21 (FIG. 1) within which the pen 14 is constrained to move. The circle 280 is repositioned on the display by use of the hand grip 12, unless the Hand Force sensor 80 signal is activated by pressure on the case top. When the user wishes to reposition the position circle 280, the user reduces pressure from the back of the case 11, thereby reducing the current on the hand force sensor 80 resulting from pressure against the button 81 on the rear bottom of the device (FIG. 4). This signals to the processing unit 240 that the position circle 280 allowing it to be moved ("dragged") on the screen of the display 275 in a direction corresponding to the A or B Hand Force signal derived from the sensor 72. The circle 280 is moved in the direction corresponding to the active A or B position and at a rate corresponding to the A or B force signal until horizontal pressure on the finger grip 12 is released. The position circle 280 is then kept at the last updated X-Y position. In FIG. 12, the updated X-Y position is indicated by 280a.
While positioned on the display 275, the position circle 280 defines an aperture into the image being drawn on the display through which the user can enter X and Y position signals, together with pen force signals, to create a graphics object for display on the screen. This is illustrated in FIG. 12, where the scripted word "Even" 283 has been entered into the image on the display 275 by use of the pen 14 while the position circle is in the position indicated by 280. The word 283 represents the trace of the tip of the pen 14. This trace is provided by continuous transmission of X and Y POS signals to the graphics processor as described above. The width, or density, of the graphics object 283 which traces the path of the pen tip is given by the sequence of hand down force signals transmitted with the X and Y position signals Movement of the position circle 280a in response to use of the grip repositions the aperture in the displayed image. In the repositioned position circle, the scripted word "if" has been entered into the image.
Thus, by moving the position circle 280 in a particular sequence of overlapping location, the user of the device 10 can selectively create a graphics object using the graphics processing unit 240, and enjoy instantaneous visual feedback of the object during the process of creation.
The design of the device 70 is intended to position the stylus 14 and grip 12 so that they can be enclosed in the span of a user's hand and operated simultaneously. This permits simultaneous input of graphics signals and force signals to reposition the drawing area enclosed in the position circle. When only graphics signals are to be input, force signals are locked out by applying sufficient hand force to the rear of the upper case to exceed a preset force. This can be applied by the rear of the hand being used to operate the stylus.
TABLE I______________________________________ 60 *function of switch bits: 61 *80h = x select 62 *40h = x pos 63 *20h = x force 64 *10h = (not assigned) 65 * 8h = a,b select 66 * 4h = a,b pos 67 * 2h = a,b force 68 * 1h = (not assigned) 69 * 70 *ADC converter inputs: 71 * 0 = x sensor position 72 * 1 = y sensor position 73 * 2 = 'A' sensor pos/force 74 * 3 = 'B' sensor pos/force 75 * 4 = hand force 76 * 5 = x sensor force 77 * 6 = left button 78 * 7 = right button 79 * 80 *xmit order: 81 * 0 = x pen pos 82 * 1 = y pen pos 83 * 2 = pen downforce 84 * 3 = 'A' sensor position 85 * 4 = 'B' sensor position 86 * 5 = hand downforce 87 * 6 = left button 88 * 7 = right button 89 * 8 = 'A' sensor force 90 * 9 = 'B' sensor force100 #define void int101 #define FORCE 0102 #define POSITION 1103 #define XON '-021'/* ---- function defs ---- */104 void init(); /*initialize SIO */105 void testxmit(); /*test request to xmit */106 void sendstr(); /*transmit result string*/107 int getstat(); /*!0 if char avail */108 int getchr(); /*char in lower byte */109 void settmr(); /*set timer */110 unsigned int gettmr(); /*get current timer value */111 void adcstb(); /*start adc cycle */112 int adcstat(); /*get adc status */113 unsigned int adcdata(); /*get adc data */114 void setswit(); /*set control bits *//* ---- global vars ----*/115 static char buffer (10) /* value buffer */116 main()117 {118 static int i; /*counter */119 init(0; /*init SIOs */120 setwit(0x44); /*set switches */123 for (i = 0; i < 10; ++i)124 buffer(i) = 0;125 for (;;)126 { /* x axis pen position */127 adcstb(0); /*start conversion */128 while (adcstat (0)) /*wait till conversion done */129 testxmit();130 buffer(0) = adcdata(0); /*get adc data */131 setswit(0x84); /*set switches */135 /* A sensor position */136 adcstb(2); /*start conversion */137 while (adcstat(2)) /*wait till conversion done */138 testxmit();139 buffer(3) = adcdata(2); /* B sensor position */140 adcstb(3); /*start conversion */141 while (adcstat(3)) /*wait till conversion done */142 testxmit();143 buffer(4) = adcdata(3);144 setswit(0x88); /*set switches */ /* y axis pen posiion */145 adcstb(1); /*start conversion */146 while (adcstat(1)) /*wait till conversion done */147 testxmit();148 buffer(1) = adcdata(1);149 setswit(0xAA); /*set switches */ /* hand downforce */150 adcstb(4); /*start conversion */151 while (adcstat(4)) /*wait till conversion done */152 testxmit();153 buffer(5) = adcdata(4); /* pen downforce */154 adcstb(5); /*start conversion */155 while (adcstat(5)) /*wait till conversion done */156 testxmit();157 buffer(2) = adcdata(5);158 setswit(0x0A); /*set switches */ /* 'A' sensor force */159 adcstb(2); /*start conversion */160 while (adcstat(2)) /*wait till conversion done */161 testxmit();162 buffer(8) = adcdata(2); /* 'B' sensor force */163 adcstb(3); /*start conversion */164 while (adcstat(3)) /*wait till conversion done*/165 testxmit();166 buffer(9) = adcdata(3);167 setswit(0x00); /*set switches */ /* left key */168 adcstb(6); /*start conversion */169 while (adcstat(6)) /*wait till conversion done */170 testxmit();171 buffer(6) = adcdata(6);171a setswit(0x44); /*set switches */ /* right button */172 adcstb(7); /*start conversion */173 while (adcstat(7)) /*wait till conversion done */174 testxmit();175 buffer(7) = adcdata(7);176 }177 }178 void testxmit()179 {180 static int i; /*counter */181 static char xmitbuf(10); /*local buffer */182 static char *cp; /*pointer to chars */183 if (!getstat()) /*char not available? */184 return;185 if (getchr() ! = XON) /*char not 'start char'? */186 return187 for (i=0; i<10;++i) /Ixfer data to local buffer */188 xmitbuf(i)=buffer(i);189 sendstr(xmitbuf,8);190}______________________________________
TABLE II______________________________________ADCSTB : POP b ;(RETURN ADDRESS) .sup. POP h ;CHANNEL NUMBER .sup. PUSH h ;(RESTORE STACK) .sup. PUSH b .sup. MOV a, ;ADDRESS .sup. OUT ADCLD ;ADC ADDRESS LOAD .sup. OUT ADCCV ;ADC STROBE .sup. RET______________________________________
TABLE III______________________________________ASCSTAT :IN ADCST ;GET SONAR STATUS ANI 00000001B ;ADC ONLY MOV l,a ;RETURN STATUS MVI h,0 RET______________________________________
TABLE IV______________________________________ADCDATA :IN ADCDA ;GET DATA MOV L,A ;RETURN DATA MVI H,O RET END START______________________________________
While we have described several preferred embodiments of our integrating graphics input device, it should be understood that modifications and adaptations thereof will occur to persons skilled in the art. Therefore, the protection afforded our invention should only be limited in accordance with the scope of the following claims.
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A graphics input device for use with a graphics processing system includes a stylus which can be manually manipulated by a user to generate graphics input signals representative of a graphics object to be drawn in a circumscribed area on a display device controlled by the graphics processing system. The graphics input device also includes a grip which can be manually manipulated by the user to generate positioning signals for repositioning the circumscribed area on the display.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to vibration-damping steel, and further relates to structural steel preferably used as members of welded structures, for example. More particularly, it pertains to steel which has excellent vibration-damping properties capable of suppressing vibrations and noise, weldability, toughness and excellent strength as well.
2. Description of the Related Art
Vibrations and the noise emanating from such vibrations have become a social problem in recent years. These vibrations include those caused by mechanical structures and heavy traffic on railways and bridges as well as those produced in facilities such as factories and work places, particularly when these are located near residential areas.
To solve such a problem, various techniques are employed, such as using sound absorbing or insulating materials, or vibration insulating materials, and increasing the stiffness of structures to avoid resonance. However, in reality, vibrations and their source are a very complex phenomenon. It is generally difficult to eliminate the causes of vibrations. Even though noise can be reduced to some extent at its source, a huge amount of investment is required.
Thus, much attention has been shifted to methods for imparting vibration-damping properties to the materials themselves which are used as structural members, thereby solving the problem of vibration and noise emanating from a structure.
Several types of steel having the vibration-damping properties mentioned above have been proposed.
For example, Japanese Patent Publication No. 60-26813 discloses a manufacturing method for a type of vibration-proof steel having a low yield point and coarse grain. This steel, however, cannot be used as structural members because of low strength and inferior toughness.
Japanese Unexamined Patent Publication No. 52-144317 discloses a type of vibration-proof steel containing Ti, Al and 3 to 40 wt. % of Cr (hereinafter all weight percentages are denoted simply by %); Japanese Patent Publication No. 57-181360 discloses a thick vibration-damping steel plate containing 1.5 to 9% of Al; and Japanese Unexamined Patent Publication No. 57-22981 discloses a type of vibration-damping steel containing 4 to 8% of Cr and 3 to 5% of Al.
These types of steel have inferior weldability and are lacking in toughness or vibration-damping properties, and are expensive since enormous amounts of alloy components are added.
In addition, Japanese Unexamined Patent Publication No. 3-1621 discloses 18-8 stainless steel having vibration-damping properties because of grain boundary oxidation. Such stainless steel also has inferior weldability and is not suitable for mass production.
SUMMARY OF THE INVENTION
An important object of the present invention is to provide low-priced steel suitable for use as structural members, which steel has excellent vibration-damping properties, weldability, toughness and excellent tensile strength, preferably not less than about 41 kgf/mm 2 , which steel is capable of being efficiently mass-produced.
In analogy to magnetic spins, strain or magnetic strain occurs in the crystal lattices of ferromagnetic steel. This strain mainly affects the inside of the steel, thus dividing it into magnetic domains.
When external forces or vibrations are applied to such steel, such forces are analogous to these magnetic strains, thereby moving the walls of the magnetic domains and creating eddy currents which occur to offset changes in magnetization because of the movements of the walls of the magnetic domains inside the ferromagnetic steel. The eddy currents in turn cause other types of strains in addition to magnetic strain. The phases of these strains are delayed with respect to the external forces, and hence vibration-damping properties are manifested in the steel which are caused by internal friction of a magnetic-dynamic hysteresis type. Such a phenomenon is reflected in the fact that pure iron has excellent vibration-damping properties. Pure iron, however, has low strength and therefore cannot, for practical reasons, be used as structural members.
As contrasted to pure iron, the inventors of this invention have already proposed a steel plate which has strength and toughness sufficient for a welded structure while maintaining the excellent vibration-damping properties of pure iron, and have described the steel plate in Japanese Unexamined Patent Publication No. 1-246575. The steel plate is prepared by adding Cu to steel having 0.08% or less of Mn and a composition similar to that of pure iron.
The inventors have investigated various methods of further improving the vibration-damping properties of the steel mentioned above, and, as a result, have now discovered that the vibration-damping properties of the steel are improved greatly by adding about 1% or more of Al to the steel. Al is an element which is capable of increasing strength without decreasing the vibration-damping properties of the steel.
The new steel in accordance with one aspect of the present invention has excellent vibration-damping properties and weldability. It comprises about 0.02 wt. % or less of C, about 0.02 wt. % or less of Si, about 0.08 wt. % or less of Mn, about 0.05 to 1.5 wt. % of Cu, about 1.0 to 7.0 wt. % of Al, about 0.008 wt. % or less of N, and Fe and incidental impurities which together constitute the remaining wt. %. The vibration-damping properties of the new kind of steel according to this invention are improved significantly over those of the steel disclosed in Japanese Unexamined Patent Publication No. 1-246575 mentioned above.
In accordance with yet another aspect this invention, there is also provided steel having excellent vibration-damping properties and used for weldability, this steel comprising about 0.02 wt. % or less of C, about 0.02 wt. % or less of Si, about 0.08 wt. % or less of Mn, about 0.05 to 1.5 wt. % of Ni, about 0.05 to 1.5 wt. % of Cu, about 1.0 to 7.0 wt. % of Al, about 0.008 wt. % or less of N, and Fe and incidental impurities which together constitute the remaining wt. %.
Although it is difficult to provide complete analyses of all reasons for defining or limiting the compositions of the ingredients of the steel according to this invention, the following remarks are believed to be relevant.
As regards the restriction to the content of about 0.02% or less of C:
The element C is present in ordinary steel for the purpose of increasing strength. However, the strength of the steel according to this invention is improved by the precipitation of Cu, so that C is not necessary in such great amounts as to increase strength. The C content is limited to about 0.02% or less, because with an excess, vibration-damping properties are reduced.
As regards the restriction to about 0.02% or less of Si:
If the Si content exceeds about 0.02%, vibration-damping properties are reduced.
As regards about 0.08 % or less of Mn:
Because Mn has an adverse effect on toughness when Cu is present to increase strength, it is preferable that the Mn content be as small as possible. The Mn content is accordingly limited to about 0.08% or less.
As regards the restriction to about 0.05 to 1.5% of Cu:
Cu is an element essential to this invention which is precipitated as fine ε-Cu by an aging treatment to improve the strength of the steel. Both the strength and the toughness of the steel can be obtained without reducing the vibration-damping properties by adding Cu to steel containing a small amount of Mn. Cu is thus an essential element in this invention. However, if the Cu content is less than about 0.05%, an advantageous effect cannot be obtained. On the other hand, if the Cu content is more than about 1.5%, hot tearing may occur, and thus the Cu content is limited within a range from about 0.05 to 1.5%.
As regards the restriction to about 1.0 to 7.0% of Al:
As described previously, Al has been discovered to improve the vibration-damping properties of steel having about 0.08% or less of Mn and a composition similar to that of pure iron. However, if the Al content is less than about 1.0%, an advantageous effect cannot be obtained. On the other hand, if the Al content is more than about 7.0%, the toughness of a welded portion of the steel decreases. The Al content is thus limited within a range from about 1.0 to 7.0%.
As regards the restriction to about 0.008% or less of N:
It is preferable that the N content be as small as possible when the toughness of the base material and the welded portion is considered. The allowable upper limit of N content is about 0.008%.
The steel in accordance with a second embodiment of the present invention contains about 0.05 to 1.5% of Ni, in addition to the elements mentioned above. Ni is capable of suppressing a tendency toward heat tearing without reducing vibration-damping properties. If the Ni content is less than about 0.05%, an advantageous effect cannot be obtained, whereas if it is more than about 1.5%, production is not economical. Thus the Ni content ranges from about 0.05 to 1.5%.
In addition to the elements described above, in this invention P and S may also be allowed as impurities up to about 0.01% and about 0.005%, respectively.
Vibration-damping properties decrease with an increase in P content which is allowable up to about 0.01%.
S, like P, is an element having an adverse effect on vibration-damping properties. When the S content exceeds about 0.005%, vibration-damping properties in particular decrease. Therefore the upper limit of the S content is about 0.005%.
The steel of this invention may be used as thick steel plate through conventional processes of melting, forging and rolling. It may also be used for wire rod, thin steel plate, shape and bar steel, etc. It is preferable that the steel be subjected to tempering in order to precipitate Cu.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Steels of various compositions, shown in Table 1, were melted and cast in accordance with conventional methods, and were hot-rolled to form steel plates A to U, each having a thickness of 25 mm. Steel containing Cu was further subjected to a precipitation aging treatment at 575° C. for one hour.
TABLE 1__________________________________________________________________________ Tensile PropertiesChemical Compositions (%) Y.S. T.S. Extensi-Steel C Si Mn Cu Al N Ni P S kgf/mm.sup.2 kgf/mm.sup.2 bility %__________________________________________________________________________A 0.005 0.004 0.06 0.75 3.3 0.003 -- 0.003 0.002 37 48 30B 0.007 0.005 0.05 1.5 2.4 0.004 -- 0.002 0.001 37 51 26C 0.006 0.005 0.04 0.96 3.0 0.002 0.75 0.002 0.001 36 47 31D 0.008 0.01 0.06 0.75 6.5 0.003 0.5 0.001 0.003 40 51 29E 0.006 0.009 0.07 0.98 1.2 0.004 -- 0.003 0.003 39 50 33F 0.02 0.015 0.07 1.0 3.5 0.002 -- 0.003 0.003 34 42 33G 0.005 0.02 0.05 0.8 3.2 0.004 -- 0.002 0.001 38 48 29H 0.007 0.005 0.05 1.5 3.8 0.003 -- 0.001 0.001 45 57 27I 0.017 0.014 0.05 0.05 3.5 0.003 -- 0.003 0.001 34 42 31J 0.006 0.007 0.04 0.88 7.0 0.003 -- 0.002 0.001 40 49 30K 0.012 0.005 0.05 0.77 1.0 0.004 -- 0.002 0.001 35 45 30L 0.006 0.003 0.06 0.75 4.0 0.008 -- 0.003 0.001 36 47 29M 0.007 0.004 0.08 1.4 3.3 0.005 1.5 0.002 0.001 44 55 27N 0.017 0.015 0.07 1.0 3.1 0.003 0.05 0.002 0.001 35 42 32O 0.006 0.006 0.05 0.94 0.015 0.003 -- 0.003 0.002 38 49 30P 0.006 0.006 0.05 -- 3.7 0.0035 -- 0.003 0.002 19 30 42Q 0.005 0.01 0.5 0.94 2.5 0.003 -- 0.002 0.001 39 54 28R 0.007 0.01 0.07 0.96 3.0 0.01 -- 0.002 0.001 41 51 29S 0.08 0.006 0.05 0.97 2.4 0.003 -- 0.002 0.001 41 54 26T 0.016 0.15 0.04 0.97 2.5 0.003 -- 0.002 0.003 42 53 27U 0.16 0.14 0.98 -- 0.015 0.005 -- 0.002 0.005 32 45 30__________________________________________________________________________ Charpy Impact Toughness of Welded Internal FrictionSteel Values vE.sub.0 kgf · m Portions vE.sub.0 kgf · m Q.sup.-1 × 10.sup.-3 Remarks__________________________________________________________________________A 29 11.0 18.7 First EmbodimentB 11 10.2 16.4 First EmbodimentC 28 12.0 15.9 Second EmbodimentD 25 12.7 15.3 Second EmbodimentE 18 11.2 15.0 First EmbodimentF 29 15.0 18.3 First EmbodimentG 27 10.3 15.7 First EmbodimentH 13 11 16.2 First EmbodimentI 28 22 19.8 First EmbodimentJ 11 10 17.3 First EmbodimentK 30 19 12.6 First EmbodimentL 27 13 14.8 First EmbodimentM 30 13 15.9 Second EmbodimentN 28 23 17.3 Second EmbodimentO 29 20 5.8 Compared ExampleP 13 11 5.4 Compared ExampleQ 1.5 0.9 4.8 Compared ExampleR 19 0.7 10.9 Compared ExampleS 20 10 1.8 Compared ExampleT 20 11 2.0 Compared ExampleU 20 15 0.5 Conventional Example__________________________________________________________________________
As shown in Table 1, the symbols A to N indicate steel plates having compositions according to the present invention. More specifically, symbols A, B and E to L indicate steel plates in accordance with the first embodiment of this invention, and symbols C, D, M and N indicate steel plates in accordance with the aforementioned second embodiment.
Symbols O to T indicate comparative steel plates in comparison with the steel plates of this invention. More specifically, symbol O indicates a steel plate having a small Al content; P, a steel plate containing no Cu; Q, a steel plate having a large Mn content; R, a steel plate having a large N content; S, a steel plate having a large C content; and T, a steel plate having a large Si content.
Symbol U indicates SS 41 (a symbol of ordinary steel specified in Japanese Industrial Standard) steel in accordance with the conventional art.
The tensile and impact properties and internal friction values Q -1 of base materials of these steel plates, along with the toughness of welded portions, were measured. Table 1 shows the results of these measurements, together with other values. Portions were subjected to submerged arc welding under a heat input of 10 kJ/mm, and the toughness values of welded joints of the portions were measured.
As will be understood from Table 1, all types of steel A to N with the element compositions of this invention exhibited a tensile strength of not less than 41 kgf/mm 2 which is highly satisfactory for weldability. The base materials and welded portions have toughness values which satisfy the need for an absorbed energy of not less than 10 kgf·m at 0° C. The steels A to N all exhibit internal friction values Q -1 ×10 -3 of not less than 12 and substantially improve vibration-damping properties.
On the contrary, the steels O to T in comparison with the steels of this invention are not capable of achieving the objects of the invention. This is because the steel O has an inferior internal friction value; the steel P has lower strength; the base material and welded portion of the steel Q have lower toughness; the welded portion of the steel R also has lower toughness; and the steel S and T have smaller internal friction values. All of these characteristics are inferior to those of the steels A to N according to this invention.
As has been described above, the present invention provides steels having excellent vibration-damping properties, weldability, toughness and a tensile strength of not less than 41 kgf/mm 2 which characteristics are very desirable for use as structural members. Thus, steels are prepared by adding Cu and about 1.0% or more of Al to steel having about 0.08% or less of Mn and a composition similar to that of pure iron.
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Steel having excellent vibration-damping properties and weldability includes about 0.02 wt % or less of C, about 0.02 wt % or less of Si, and about 0.08 wt % or less of Mn. This steel also includes about 0.05 to 1.5 wt % of Cu, about 1.0 to 7.0 wt % of Al, about 0.008 wt % or less of N, and Fe and incidental impurities which together constitute the remaining wt %.
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CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of and priority to French Patent Application No. 13/61056, filed Nov. 13, 2013, which is hereby incorporated by reference herein in its entirety.
BACKGROUND
The invention relates to “active implantable medical devices” as defined by the 90/395/CEE directive of Jun. 20, 1990 of the European community counsel. This definition notably includes the devices that continuously monitor the cardiac activity and deliver if necessary to the heart electrical pulses of stimulation, cardiac resynchronization, cardioversion and/or defibrillation in case of a rhythm disorder detected by the device. It also includes the neurological devices, the cochlear implants, etc., as well as the device for pH measurement or other intracorporeal parameters.
These devices include a generator consisting of a metal housing, usually made of titanium, on which a connector head is mounted. The connector is provided with housings for mechanically and electrically connecting one or more leads to the generator housing, the leads having at their distal end various electrodes of sensing, pacing and defibrillation. The connection of the connector to various electronic circuits involves the realization of several electrical feedthroughs, between connectors assembled on the upper surface of the housing (outer side), and the interior volume of the housing where these circuits are (inner side).
Besides the connection pins on the connector head, other feedthroughs can also be provided, for example to ensure a connection with a surface electrode placed on the outside of the housing, or at the sensor integrated with a lead of the device. These feedthroughs can also be found in sub-components of medical devices such as batteries and capacitors. Such a feedthrough is for example described in EP2377573 A1 (Sorin CRM SAS).
The technique described in the EP2377573 A1 document is to superficially oxidize the outer side of the titanium housing or to deposit an insulating layer (e.g. silicon dioxide) on the outer side, and, on the inner side, to dig into the wall throughout its thickness, so as to form a contour groove defining a closed area or “islet” dedicated to the electrical conduction. This islet, created in the mass of the wall of the housing, is physically and therefore electrically isolated from the rest of the body of the housing.
An electrical connection is then performed on each side of the islet by providing on each side thereof a contact pad on which for example a connection wire to a terminal of the electronic circuit, or a connection pin of the connector, is welded. The presence on the outer side of the insulating layer, which is not inground, ensures a perfect hermeticity of the feedthrough and prevents penetration of fluid inside the housing. This layer also has the advantage of being biocompatible, biostable and resistant to corrosion.
The method can also be developed without significant additional cost, in so far as it uses only proven conventional techniques. However, this technique leaves some mechanical fragility. Indeed, after excavation of the peripheral groove surrounding the islet, the latter is completely detached from the rest of the wall of the housing (which is precisely essential to ensure the electrical insulation of the feedthrough) and is only connected to this wall by the thin superficial layer that forms an oxide “membrane” or “diaphragm” whose thickness is typically 10 to 15 microns (for a wall thickness of about 300 microns).
This residual fragility, which is intrinsic to the thinness of the oxide layer, is further increased by the rather average tolerances achieved downhole during the digging of the groove. This can locally lead to the appearance of cracks or other micro-defects, precisely near the thin oxide layer which holds the islet and wherein stress biasing the structure may be concentrated, for example because of the wires or pins welded onto the central islet.
Certain proposed embodiments of the present invention provide a solution of mechanical reinforcement of this known structure to make it more robust and tolerant to the presence of micro-defects.
Another inherent drawback in the structure described above is that it only allows to passively convey (ohmic, purely resistive conduction) an electrical signal between the inside and outside of the housing. Therefore, to provide a filter (series or parallel) to the feedthrough, it is necessary to provide an external capacitive disc carried on the inner face of the feedthrough, to which the disc is mechanically and electrically connected, for example by a conductive adhesive. This is a relatively expensive step from the industrial viewpoint since it requires numerous sub-steps that can also cause reliability problems.
Certain proposed embodiments of the present invention provide various collateral advantages, including the ability to integrate into the known structure, improved according to the invention, additional functional elements, such as an RF antenna (for the purpose of RF telemetry), electrodes, sensor elements etc. Indeed, the RF antennas, for example, are currently made from a metal wire outside the housing, which is connected to the internal electronic circuitry through a dedicated feedthrough which is then overmolded in a biocompatible plastic matrix. Again, the connection and industrialization are complex and induce an overall volume significantly higher than that of devices without RF antenna.
SUMMARY
The present disclosure relates to a housing of an active medical device (or housing element) including a metal wall having an outer side and an inner side, said wall being provided with at least one electrically insulated and hermetic feedthrough for electrical connection through the wall. The housing further includes in the region of the feedthrough: on the inner side of the wall, a closed contour groove delimiting in the wall a metal islet physically and electrically isolated from the rest of the wall, said groove extending throughout the thickness of the wall; and on the outer side of the wall, an external electrically insulating layer formed above the wall and extending over a region located at least to the right of the groove and beyond either side of the groove, this external insulating layer including a recess formed to the right of the islet in the entire thickness of the insulating outer layer.
According to certain embodiments, this housing further includes, on the outer side of the wall in the region of the feedthrough, an outer electrically conductive layer formed over the insulating outer layer and extending over said region. The electrically conductive layer at least in alignment with the groove and beyond each side of the groove, the islet being mechanically supported and sealed by both conductive and insulating outer layers. The electrically conductive outer layer can be a metal layer of titanium, platinum, palladium, gold or alloys thereof. The insulating outer layer may be an oxide layer of the metal of the wall, formed on a fraction of the thickness of this wall, or an insert layer, deposited on the surface of the wall.
According to a first embodiment of the invention, the recess also extends throughout the thickness of the conductive outer layer, so as to provide in the bottom of the recess a contact pad to the islet at the outer side of the housing block in the area of the feedthrough. In this case, the conductive outer layer may extend beyond the region of the feedthrough defining on an area a first plate of a parallel filter capacitor of the feedthrough, the other plate of the capacitor being formed by the region of the wall extending opposite the first plate.
According to a second embodiment of the invention, the recess is filled with the material of the conductive outer layer, thereby electrically connecting the islet to the conductive outer layer in the region of the feedthrough. In this case, the housing may further include in the region of the feedthrough, on the inner side of the wall, an electrically insulating inner layer formed on top of the wall and extending over the region of the islet It further includes an electrically conductive inner layer formed over the inner insulating layer and extending over the region of the islet, so as to form a contact pad to the islet, inner side of the housing. The conductive inner layer thus defines a first plate of a series filter capacitor through the feedthrough, the other plate of the capacitor being formed by the region of the wall extending opposite the first plate.
On the other hand, the conductive outer layer may extend beyond the region of the feedthrough according to a predetermined pattern defining a RF antenna, a sensor electrode or a detection/stimulation electrode element.
Finally, the housing may include in the region of the feedthrough, on the outer side of the wall, a stack formed in the insulating outer layer of alternately conductive and insulating multiple additional outer layers.
According to another embodiment, a method of creating a feedthrough in a housing of an active implantable medical device is provided. The method includes providing a housing having an outer wall and an inner wall, creating an electrically insulating outer layer on the outer wall of the housing, and creating an electrically conductive outer layer on the outside of the electrically insulating outer layer. The method further includes forming a recess in at least the electrically insulating outer layer, extending through the electrically insulating outer layer to the outer wall of the housing and forming a contour groove in the inner wall of housing, extending through the width of the wall, at a location not aligned with the recess formed in the electrically insulating outer layer. The contour groove creates an islet in the wall of the housing, the islet being electrically and physically isolated from the rest of the wall. The islet is aligned with the recess formed in the electrically insulating outer layer.
According to yet another embodiment, a method of preparing a substrate for creation of a feedthrough is provided. The method includes providing a first and a second substrate, creating a first electrically insulating layer on a first side of the first substrate, and creating a second electrically insulating layer on either the second side of the first substrate or a first side of the second substrate. The method further includes welding together the first substrate and the second substrate forming a welded structure. The welded structure includes a first electrically insulating layer on the outside of the welded structure, a second electrically insulating layer between the first and the second substrate, one of the first and second substrate between the first and second electrically insulating layers forming the retained substrate, and the other of the first and second substrate forming an exposed substrate. The method further includes thinning the exposed substrate so as to form an outer conductive layer from the substrate.
DRAWINGS
Further features, characteristics and advantages of the present invention will become apparent to a person of ordinary skill in the art from the following detailed description of preferred embodiments of the present invention, made with reference to the drawings annexed, in which like reference characters refer to like elements and in which:
FIG. 1 is an elevation view, in section, of a feedthrough according to the prior art.
FIG. 2 is an elevation view, in section, of a feedthrough according to a first embodiment of the invention.
FIG. 3 is an elevation view, in section, of a feedthrough according to a second embodiment of the invention.
FIG. 4 is a top view showing an RF antenna integrated to the housing of the active device and realized by applying the teachings of the second embodiment of the invention.
FIGS. 5 and 6 are counterparts of FIGS. 2 and 3 to illustrate an improvement wherein the feedthrough further includes a filtering series capacitor.
FIG. 7 illustrates an improvement of the second embodiment of the invention implementing a multi-layer structure.
FIG. 8 shows the successive steps for producing the structure of FIG. 2 according to the first embodiment of the invention.
FIG. 9 shows the successive steps for producing the structure of FIG. 3 according to the second embodiment of the invention.
FIG. 10 illustrates an alternative preparation of the substrate for the realization of the feedthrough according to the invention.
DETAILED DESCRIPTION
FIG. 1 shows a structure according to the prior art, such as that described in the abovementioned EP 2377573 A1. Reference 10 designates the titanium metal housing of the generator, or a separate titanium plate is a metal part which is then attached to the housing and welded thereto. An insulating layer 12 is formed above the wall 10 , at least on the external face of the housing. This insulating layer 12 may be formed by oxidation of the titanium of the housing 10 on a controlled depth, or by depositing a layer of insulating material, for example silicon dioxide, on the surface of the thickness 10 of the titanium housing. The thickness of the insulating oxide layer 12 is for example of the order of 10 microns for a thickness of the housing of about 300 microns.
The structure further includes a conductor islet 14 formed in the thickness of the housing 10 by digging a groove 16 . In the direction of depth, the groove 16 is recessed from the inner side of the housing in the entire thickness of the wall 10 of the metal housing. However, the insulating layer 12 is left intact, so that the islet 14 can be supported by the bridge of material formed by the insulating layer 12 between the area of the islet and the remainder of the metal layer of the housing. The outer insulating layer 12 also forms a hermetic barrier between the inside of the case and the external environment. In the plane of the surface of the housing, the groove 16 is recessed on a closed contour, so as to physically and electrically completely insulate the islet 14 from the remainder of the housing 10 around its entire periphery.
This structure also has an opening 18 formed in the outer side of the thickness of the insulating oxide layer 12 in alignment with the islet 14 , so as to expose an area on which a wire 20 or a pin can be soldered to ensure electrical contact, via solder 22 , with the central conductor islet 14 . On the inner side, the islet 14 is connected to a connection wire to the electronic circuits enclosed in the housing of the generator 10 . The connection is, for example by soldering of a connection wire (not shown), so as to produce a feedthrough insulated and sealed from the housing, from this internal connection wire to the pin or outer wire 20 , at the opposite side of the housing 10 . Other connection techniques may alternatively be used, such as soldering, wire bonding or contacting via a conductive elastic member.
This structure has the characteristic that the islet 14 is only connected, and mechanically supported, by the thin bridge of material 24 of the oxide layer 12 . This region, particularly the bottom 26 of the groove 16 , is particularly fragile. Defects or micro-cracks that weaken the bridge or “diaphragm” 24 , already fragile due to its very low thickness, can appear during the process of manufacturing.
FIG. 2 illustrates a first embodiment according to the invention. The preferred embodiments deposit on top of the insulating outer oxide layer 12 an additional, conductive outer layer 28 , e.g. by depositing a metallization of titanium or of another material such as platinum, palladium, gold and alloys thereof in a thickness of the order of several hundred nanometers to several micrometers. Titanium is preferred because of its higher affinity to the thickness of the underlying wall 10 (same expansion coefficient) and of its well-known properties of biocompatibility.
In the embodiment illustrated in FIG. 2 , the conductive outer layer 28 is deposited before digging the opening 18 designed to achieve the initial contact with the conductor islet 14 , which reduces handling constraints on the structure, strengthening thereof particularly during excavation of the groove 16 . The method thus comprises forming the outer insulating layer 12 (deposition of an insert material or of the surface oxidation of the titanium of the wall 10 ) then the conductive outer layer 28 (metalizing) on the whole extent of the outer side of the wall 10 . The opening 18 is formed in a subsequent step, so as to expose a contact with the central conductor islet 14 for soldering of a wire or a pin, as in the configuration illustrated in FIG. 1 .
Along with the recessing of the opening to make contact 18 , it is possible to etch the contours of the metallization 28 and of the insulating outer layer 12 on a predetermined surface, so as to define a structure of capacitor C 1 , the layers 10 and 28 forming the plates of this capacitor and the insulating oxide layer 12 forming the dielectric. If the conductive outer layer 28 is connected to the ground, an element for parallel filtering integrated to electrical feedthrough of the housing is thus obtained. The oxide insulating layer 12 is structured in the desired method, for example by photolithography.
The resulting structure allows for strengthening of the mechanical rigidity of the material bridge mechanically connecting the islet 14 to the rest of the wall of the housing 10 (due to the increase in thickness of material by adding the outer layer 28 ) as well as of sealing. This embodiment also provides integration of a filtering capacitive element (of a typical value in the order of 500 pF), without any mounted additional components. Furthermore, the arrangement of FIG. 2 provides the possibility of structuring the conductive outer layer 28 and the insulating outer layer 12 so as to produce elements such as a sensing electrode, a capacitive sensor element or a biochemical sensor, etc.
FIG. 3 illustrates a second embodiment of the invention. Compared to the foregoing, in this embodiment the oxide insulating layer 12 is structured, particularly to release the contact area to form the opening 18 , before depositing the conductive outer layer (metallization) 28 . Therefore, when the material of the conductive layer 28 is deposited during the step of metallization, the material enters the opening 18 formed in the oxide layer 12 and comes into contact 30 with the conductor islet 14 , thus ensuring electrical continuity between first the islet 14 and the circuits to which it is connected inside, and then the outer conductive layer 28 .
In addition to strengthening the mechanical strength and the tightness of the material bridge connecting the islet to the rest of the housing (in the same method as in the first embodiment shown in FIG. 2 ), this technique allows to widen the electrical connectivity with the outside, through direct contact between the outer metallization (conductive layer 28 ) and the central islet 14 .
One advantage of this embodiment is the ability to deport the external connecting elements elsewhere than at the vertical of the islet, thus avoiding mechanically stressing the fragile micro-structured area directly through a wire or a pin providing electrical contact at this very location. Another advantage is the ability to etch the conductive outer layer 28 so as to define the electronic elements to be electrically connected to the islet For example, as illustrated in FIG. 4 , a loop-shaped RF antenna 32 extends in a perfectly controlled geometry between two contact points 30 and 30 ′ to respective conductor islets, interior, connected to the electronic circuits of the generator. Such an antenna may particularly be used for wireless communication (telemetry) and/or battery charging via an inductive coupling. The technique of the invention makes it easy to give any suitable shape such as a loop, a spiral, a square, etc. or even a single straight antenna.
It is also possible to structure the conductive outer layer 28 so as to define a detection/stimulation electrode or a surface for a sensor for physico-chemical variables or physical parameters detected by resistive and/or capacitive impedance variations. The metal electrode provides a greater and independent sensing surface compared to that of titanium micromachining. On the other hand, the outer metallization may also be used for a capacitive detection, using the structure of the capacitor defined by the conductive layers 10 and 28 separated by the insulating layer 12 .
FIGS. 5 and 6 are counterparts of FIGS. 2 and 3 , forming a series capacitor filter directly integrated to the feedthrough. This improvement is applicable to any of the embodiments described above. To realize this series filter, the wall 10 of the housing, on the inner side, includes an insulating layer 34 coated with a conductive layer 36 . The inner layers 34 , 36 are made in the same method as the corresponding outer layers 12 , 28 , by implementation of similar techniques, these layers 34 , 36 being deposited on the inner side of the wall 10 before digging of the groove 16 .
In the plane of the surface of the housing, these layers 34 , 36 extend on the surface of the islet 14 and define a capacitor C 2 whose armatures are formed of the titanium of the wall 10 in the region of the islet and by the inner conductive layer 36 on the one hand, and the dielectric is formed by the inner insulating layer 34 , on the other hand. If the welding on the inner conductive layer 36 of a wire connecting to the internal circuits of the generator is performed, a feedthrough incorporating a series filter capacitor C 2 is thus produced, without reporting any additional component, for example for the purpose of additional filtering.
FIG. 7 illustrates a further embodiment, applicable to the embodiment of FIG. 3 . In this case, additional, alternately insulating or conductive, layers 38 , 40 , are formed on the above conductive outer layer 28 so as to define a multiple stack on the outer side of the housing. Stacking these multiple layers has the double advantage of being able to constitute an element such as a sensor or an advanced electronic function requiring several layers (e.g. a transistor); and further strengthening the structure from the mechanical and sealing point of view, the successively deposited layers increasing the thickness of the material bridge connecting the conductor islet 14 to the rest of the housing.
FIG. 8 shows the successive steps for producing the structure of FIG. 2 according to the first embodiment of the invention. The starting element is the titanium housing 10 (step a), on which insulating layers are created on both sides, with an outer insulating layer 12 and an inner insulating layer 34 (step b). These layers can be made by oxidation of the titanium housing 10 on a controlled depth, or by depositing a layer of insulating material, for example of silicon dioxide on the surface 10 of the housing thickness. The thickness of each of the layers 12 , 34 is for example of the order of 10 microns to a thickness of the housing of about 300 microns.
These layers 12 and 34 may be made for example by thermal oxidation or by any other method such as plasma oxidation or chemical deposition. It is also possible to proceed by anodization, by subjecting the housing to a potential difference, and by simultaneously keeping it in contact with a solution of water and sulfuric acid, by soaking or with help of a brush-electrode.
The next step (step c) consists in forming the conductive layer 28 outer side, for example by vacuum deposition.
The next step (step d) is a step of structuring of the conductive outer layer 28 , in particular to define the opening 18 that will subsequently achieve the contact, and to delimit the extent of the metal layer 28 to notably adjust the value of the series capacitor C 1 ( FIG. 2 ) associated with the feedthrough.
The next step (step e) is a step of etching the insulating outer oxide layer 12 , in particular to realize the exposure of the conductive layer 10 on the outer side of the housing by the opening 18 . This step may also be accompanied by an optional deletion of the insulating oxide layer 34 on the inner side of the housing.
The next step (step f) is to make the conductor islet 14 physically isolated in the thickness of the housing 10 by digging the groove 16 in the entire thickness of the housing. The widening of the groove can be made by various processes in themselves known, e.g. by chemical (interaction of species reactive with the titanium) or physical (ion bombardment) selective etching, or by any micro-structuring method, laser engraving, etc. These methods may also be combined with each other to minimize the time necessary for titanium cutting. The structure, illustrated in FIG. 2 , is finally obtained after the step f.
Note also that the groove is not necessarily cylindrical. It can also have a conical shape, for example if one uses a wet etching technique that is not perfectly directional. Also note that in this implementation, the step of forming the islet (step f) is performed after the steps of deposition of the metallization (step c) and of structuring of the outer insulating oxide layer (step e). Thus, the stresses optionally suffered by the material bring no risk of weakening the final structure, to the extent that the wall of the housing 10 is still solid, because it has not yet been reduced by the digging of the groove 16 .
FIG. 9 shows the successive steps for producing the structure of FIG. 3 according to the second embodiment of the invention. The first steps a and b are identical to those of FIG. 8 of the previous embodiment.
However, the following step (step c) is a step of structuring the insulating outer oxide layer 12 , using comparable techniques to those that have been mentioned in connection with step e in FIG. 7 , including for forming the opening 18 .
The next step (step d) is the depositing of the conductive outer layer 28 by metallization according to comparable techniques to those set forth above with respect to step c of Figure, with the only difference that this deposition occurs after structuring of the underlying oxide layer 12 . This in particular allows filing the opening 18 , formed in the preceding step, so as to make the direct contact catch 30 with the titanium of the wall of the housing 10 .
The next step (step e) is a structuring of the conductive outer layer 28 , according to comparable techniques to what has been exposed above in step d of FIG. 8 . This step may be followed by an optional step of removing the oxide insulating inner layer 34 over the whole extent of the substrate.
The final step (step f) is the formation of islet 14 by digging of the groove 16 in the same method as that of the corresponding step f of FIG. 8 . The final structure obtained after this step f is the one illustrated in FIG. 3 .
FIG. 10 illustrates a variant for the preparation of the substrate for the realization of the feedthrough according to the invention. In this variant, instead of using a homogeneous titanium substrate on which a metallization layer is deposited, two titanium substrates 10 and 10 ′, are separately prepared. The substrates 10 and 10 ′ may have a substantially equal thickness (typically 300 microns), but in other embodiments may have differing thicknesses. On one of the substrates (as illustrated), or on both, an oxide layer 12 , 34 is formed in the same method as the one described above for step b illustrated in FIG. 8 .
The two substrates are superimposed and then welded to one another by a thermal process, thermo-compression or the like. To facilitate this welding step, an additional layer may previously be added to one or the other of the substrates 10 or 10 ′. At the end of this operation, a composite substrate is obtained including an oxide inner layer 12 (which originally was present on one and/or the other of the substrates 10 , 10 ′ prior to welding) and supporting an outer conductive layer, namely the thickness of the titanium substrate 10 ′. After thinning, the layer 10 ′ may play the same role as the metallization 28 of the preceding embodiments, the basic structure obtained being comparable to that previously obtained at the end of step c illustrated in FIG. 8 . The process continues with steps similar to what has been described above for steps d to f in FIG. 8 , starting from this composite basis structure.
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A housing of an active medical device includes a metal wall having at least one feedthrough for an electrical connection through the wall. In the area of the feedthrough, the housing wall includes a contour groove extending through the thickness of wall, defining a metal islet electrically and physically isolated from the rest of the wall. The housing wall further includes an electrically insulating outer layer on the outer side of the wall extending over a region in alignment with the groove and beyond either side of the groove. The insulating outer layer includes a recess formed in alignment with the islet. The wall further includes an electrically conductive outer layer formed outside of the insulating layer and extending over the region in alignment with the groove and beyond either side of the groove. The islet is mechanically supported by the insulating and conductive outer layers.
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BACKGROUND OF THE INVENTION
[0001] It is a typical process in computer information systems to transfer data stored in a storage system to application server computers, process the transferred data in the server computers, and then store the processed results back in the storage system. Some such processes read large amounts of data from storage systems but generate results of more manageable size. For example, indexing of files to enable searching of the file contents, such as full-text searching, requires transferring various files from a storage system to an index server, parsing of the transferred files, extracting text from the files, and storing each unique word identified in the files into an index data base. The size of the extracted text is usually small (e.g., in the kilobyte range) but the original files to be transferred and processed can often be quite large (e.g., in the megabyte range or larger) because the files contain not only text, but also other data, such as images, sounds, movies, and the like.
[0002] The large size of these files consumes network bandwidth and processing resources in the index server when the files are transferred, parsed and processed, particularly, when there are massive amounts of files to be indexed. For example, in a large archive storage system storing petabytes of data, the problem can become severe, causing the indexing process to take a very long time and consume a large amount of network and server resources. Another example of a typical indexing process is creating a thumbnail image from a larger image. In both cases, the problem is rooted in the transfer of large amounts of data through the network, thereby taking up available bandwidth that might be better used for other purposes, and also in consuming large amounts of processing resources in the application servers, which also might be used for other purposes.
[0003] A number of different types of communication protocols and methods for facilitating access between servers and storage systems are currently in use. These include NFS (Network File System) protocol, CIFS (Common Internet File System) protocol, and the like. For example, NFS and CIFS protocols are widely used by file servers such as Network Attached Storage (NAS) devices, and so forth. Also the Extensible Access Method (XAM) interface standard has recently been defined. The XAM standard defines an interface method for access across applications, management systems and storage systems to create uniform access to information. XAM annotates objects with metadata providing for the management of information at a high level. This coupling allows policy services to make informed decisions about the management of objects in storage without referring back to the application and without impacting the application. XAM provides a standardized interface and metadata to communicate with object storage devices to achieve interoperability, storage transparency, and increased efficiency. While the above protocols and methods are discussed in exemplary embodiments of the invention, the invention is not limited to any particular communication methods or protocols. Related art includes US Pat. Appl. No. US2005/0278293 to Imaichi et al., filed Jan. 18, 2005, entitled “Document Retrieval System, Search Server, and Search Client”, and “Information Management-Extensible Access Method (XAM)—Part 1: Architecture, Version 1.0, Working Draft”, Storage Networking Industry Association, San Francisco, Calif., Apr. 2, 2008, the entire disclosures of which are incorporated herein by reference.
BRIEF SUMMARY OF THE INVENTION
[0004] Various exemplary embodiments of the invention disclosed herein include methods, systems and computer programs stored on computer readable mediums for reducing workloads of application or index server computers, while also decreasing network traffic, by offloading a portion of the information processing burden from the server computers to a storage system. These and other features and advantages presented herein will become apparent to those of ordinary skill in the art in view of the following detailed description of the preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The accompanying drawings, in conjunction with the general description given above, and the detailed description of the preferred embodiments given below, serve to illustrate and explain the principles of the preferred embodiments of the best mode of the invention presently contemplated.
[0006] FIG. 1 illustrates an exemplary hardware and logical configuration in which first embodiments of the invention may be applied.
[0007] FIG. 2 illustrates an exemplary structure of a file type table.
[0008] FIG. 3 illustrates an exemplary structure of a text reader table.
[0009] FIG. 4 illustrates an exemplary process flow of a management program for managing tables.
[0010] FIG. 5 illustrates an exemplary process flow of a storage system control program for handling read, write and update requests.
[0011] FIG. 6 illustrates an exemplary process flow of a read request.
[0012] FIG. 7 illustrates an exemplary hardware and logical configuration in which second embodiments of the invention may be applied.
[0013] FIG. 8 illustrates an exemplary data structure of an object with data fields.
[0014] FIG. 9 illustrates an exemplary data structure of an update list having pointers to fields of objects.
[0015] FIG. 10 illustrates an exemplary data structure of a table containing fields holding extracted text and management information.
[0016] FIG. 11 illustrates an exemplary conceptual diagram of available policies.
[0017] FIG. 12 illustrates an exemplary process flow of a storage system control program.
[0018] FIG. 13 illustrates an exemplary process flow of a background text extraction process.
[0019] FIG. 14 illustrates an exemplary process flow of a background text deletion process.
[0020] FIG. 15 illustrates an exemplary process flow of a write request.
[0021] FIG. 16 illustrates an exemplary process flow of a read request.
[0022] FIG. 17 illustrates an exemplary process flow of an export request.
[0023] FIG. 18 illustrates an exemplary data structure of a job object in the storage system.
[0024] FIG. 19 illustrates an exemplary process flow of a job request.
[0025] FIG. 20 illustrates an exemplary process flow of a background job.
DETAILED DESCRIPTION OF THE INVENTION
[0026] In the following detailed description of the invention, reference is made to the accompanying drawings which form a part of the disclosure, and in which are shown by way of illustration, and not of limitation, exemplary embodiments by which the invention may be practiced. In the drawings, like numerals describe substantially similar components throughout the several views. Further, it should be noted that while the detailed description provides various exemplary embodiments, as described below and as illustrated in the drawings, the present invention is not limited to the embodiments described and illustrated herein, but can extend to other embodiments, as would be known or as would become known to those skilled in the art. Reference in the specification to “one embodiment” or “this embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention, and the appearances of these phrases in various places in the specification are not necessarily all referring to the same embodiment. Additionally, in the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that these specific details may not all be needed to practice the present invention. In other circumstances, well-known structures, materials, circuits, processes and interfaces have not been described in detail, and/or may be illustrated in block diagram form, so as to not unnecessarily obscure the present invention.
[0027] Furthermore, some portions of the detailed description that follow are presented in terms of algorithms and symbolic representations of operations within a computer system. These algorithmic descriptions and symbolic representations are the means used by those skilled in the data processing arts to most effectively convey the essence of their innovations to others skilled in the art. An algorithm is a series of defined steps leading to a desired end state or result. In the present invention, the steps carried out require physical manipulations of tangible quantities for achieving a tangible result. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals or instructions capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, instructions, or the like. It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise, as apparent from the following discussion, it is appreciated that throughout the description, discussions utilizing terms such as “processing”, “computing”, “calculating”, “determining”, “displaying”, or the like, can include the actions and processes of a computer system or other information processing device that manipulates and transforms data represented as physical (electronic) quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system's memories or registers or other information storage, transmission or display devices to achieve a tangible real-world result.
[0028] The presented embodiments relate in part to a system for performing the operations herein. This system may be specially constructed for the required purposes, or it may include one or more general-purpose computers selectively activated or reconfigured by one or more computer programs. Such computer programs may be stored in a computer-readable storage medium, such as, but not limited to magnetic disks, optical disks, read-only memories, random access memories, solid state devices and drives, or any other type of media suitable for storing electronic information. The algorithms and displays presented herein are not inherently related to any particular computer or other apparatus. Various general-purpose systems may be used with programs and modules in accordance with the teachings herein, or it may prove convenient to construct a more specialized apparatus to perform desired method steps. The structure for a variety of these systems will appear from the description set forth below. In addition, the present invention is not described with reference to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of the invention as described herein. The instructions of the programming language(s) may be executed by one or more processing devices, e.g., central processing units (CPUs), processors, or controllers.
[0029] Exemplary embodiments, as will be described in greater detail below, provide systems, methods and computer programs for a storage system having a function to extract text from a file or object so as to offload the process of text extraction from index servers to the storage system and thereby reduce network traffic. The method for extracting the text depends on the type of original file which is to undergo the text extraction. Types of files can be distinguished in various manners, such as by identifying the extension of the file name or by referring to the MIME (Multi-purpose Internet Mail Extension) type. The storage system provides an interface to retrieve the extracted text from the storage system for delivery to index servers. The interface can be implemented by using a standard interface, such as NFS or XAM, or with a proprietary interface. The storage system may also include a management interface to record the time of text extraction and the manner in which the text is extracted text, and this information can be maintained in the storage system for future use. The management interface also may be applied to control how other storage functions are applied to the extracted text.
[0030] In a preferred embodiment, a network-attached storage system provides a text extraction function to an index server. The text extraction function is operative to extract text from files stored on the storage system when the index server requests a file on the storage system and is identified by the storage system as a requestor that should receive extracted text rather than the entire requested file. The index server communicates with the storage system by using the NFS protocol or other suitable communications protocols and methods. When the storage system completes the text extraction for the requested file, the storage system sends the extracted text to the requesting index server instead of the returning the entire requested file, thereby reducing bandwidth used and reducing the amount of processing required at the Index server.
[0031] Exemplary System and Logical Structure
[0032] FIG. 1 illustrates an overview of a computer information system consisting of a plurality of computers in communication with a storage system via a network, such as a LAN (local area network) 10002 , WAN (wide area network) or other suitable communication media. In the illustrated embodiment, an application server computer 10000 , an index server computer 10001 , a management server computer 10100 , and a storage system 10200 are operatively connected for communication with each other via LAN 10002 . Application server 10000 may perform input/output (I/O) operations, such as reading or writing files to and from storage system 10200 . Storage system 10200 stores files received in I/O operations from application server 10000 , and extracts text from these files, as described further below. Index server 10001 is configured to receive the extracted text from storage system 102000 instead of receiving entire files containing additional data, such as images, videos, and the like.
[0033] Each of application server 10000 , index server 10001 and management server 10100 may be a generic computer including a CPU 10102 , a memory 10101 , a user interface (I/F) 10103 , and a network port, such as a LAN port 10104 , as illustrated with respect to management server 10100 . Further, management server 10100 includes a management program 10105 stored in memory 10101 of management server 10100 , and executed by CPU 10102 of management server 10100 to enable a user to view and change the settings of the storage system 10200 , such as via the user interface 10103 .
[0034] Storage system 10200 has a network interface, such as LAN I/F 10202 to facilitate communication with the server computers via LAN 10002 . Storage system 10200 also includes a storage area 10221 for storing data, such as files 10222 , which includes at least one storage medium, such as one or more hard disk drives (HDDs), optical drives, solid state storages, or the like, controlled by a storage area controller 10220 , which may be a disk controller, etc. Storage system 10200 includes a CPU 10201 which executes a storage system control program 10301 stored in a memory 10203 or other computer readable medium. Storage system control program 10301 not only processes I/O requests sent from applications on application server 10000 and/or index server 10001 , but also carries out the function of extracting text from files when required. Storage system control program 10301 also communicates with management server 10100 and processes management requests for managing access to extracted text from the servers. Memory 10203 also can contain several data structures and management information tables, including a file type table 10302 and a text reader table 10303 , as discussed further below.
[0035] FIG. 2 illustrates the structure of file type table 10302 . File type table 10302 indicates a file type definition 20002 of a MIME type for each corresponding file name extension 20001 . The storage system control program 10301 can identify the type of a particular file by referring to file type table 10302 and matching the extension of the particular file with file name extension name 20001 in file type table 10302 . The storage system control program 10301 then is able to determine how to extract text from a particular file based on the determined file type. Any of various known methods may be used for carrying out the actual text extraction by storage system control program 10301 . For example, US Pat. Appl. No. US2005/0278293 to Imaichi et al., incorporated by reference above, describes text extraction techniques. However, any other text extraction techniques known in the art, or that may become known in the art, can be used, and the invention is not limited to any particular text extraction technology.
[0036] FIG. 3 illustrates the structure of text reader table 10303 . Text reader table 10303 defines entities (text readers) to which the extracted text is made available. In other words, a text reader is a registered extracted data receiver that can be identified by the storage system as an entity that should receive only extracted text, rather than an entire file. The entity can be identified as a text reader by an ID of Requestor 30301 . For example, the ID may include the IP address of the index server and/or a user name of the indexing server application. For instance, in these embodiments, an example of a text reader is the index server 10001 , although the invention is not limited to providing extracted text to index servers. Typically, if a server computer that is not listed in text reader table 10303 requests to read a file, the storage system 10200 returns the file without making any modifications to the file content. However, according to exemplary embodiments of the invention, when the storage system 10200 receives a request from a computer that is registered as a text reader in the text reader table 10303 , the storage system 10200 extracts text from the specified file and returns the extracted text to the requesting computer instead of returning the entire file contents.
[0037] Process Flows
[0038] FIG. 4 illustrates an exemplary process flow of management program 10105 executed by management computer 10100 , such as for editing and updating file type table 10302 or text reader table 10303 .
[0039] At step 40001 , management program 10105 receives a request from a user, such as a system administrator, via the user interface 10103 , or the like.
[0040] At step 40002 , management program 10105 determines whether the received request is a table management request.
[0041] At step 40003 , when the received request is a table management request, management program 10105 sends a table read request to the storage system 10200 , which requests that the storage system 10200 read the current file type table 10302 and/or text reader table 10303 , and return the current information contained therein to management computer 10100 .
[0042] At step 40004 , management computer 10100 receives the requested tables and displays the information contained therein to the user that requested the information so that the user can edit the tables as desired.
[0043] At step 40005 , After the user edits the information contained in tables 10302 , 10303 , management program 10105 sends the updated information to storage system 10200 .
[0044] At step 40006 , when the request received by management program 10105 is not directed to management of the file type table 10302 or text reader table 10303 , then the request is erroneous for purposes of the present invention, and the request will not result in retrieval or display of the file type table 10302 or text reader table 10303 stored in memory 10203 .
[0045] FIG. 5 illustrates an exemplary process flow of an overall process carried out by storage system control program 10301 in response to receiving a request from a computer via LAN 10002 .
[0046] At step 50001 , storage system control program receives a request from a computer, such as application server 10000 , index server 10001 , or management computer 10100 . Generally, the request will be one of the following: a write request, which contains a name of a file to be stored and the content of the file to be stored; a read request, which contains a name of a file to be read; a table read request, which requests reading and return of the file type table 10302 and/or text reader table 10303 ; or a table update request, which provides new content for updating the file type table 10302 and/or text reader table 10303 . Each such request also contains the ID of the requestor, and, for example, may be a standard read or write request, such as in accordance with NFS protocol.
[0047] At step 50002 , storage system control program 10301 determines whether or not the received request is a write request, which contains a name (address) of a file to be stored and the contents (data) of the file to be stored. If the request is a write request, the process goes to step 50003 ; if not, the process goes to step 50004
[0048] At step 50003 , when the request is a write request, the request is typically from a computer such as application server 10000 for updating application files contained in storage system 10200 , or the like. Storage system control program 10301 stores the file data included with the write request in the storage area 10221 .
[0049] At step 50004 , when the request is determined to not be a write request, storage system control program 10301 next determines whether the request is a read request containing a name of a file to be read.
[0050] At step 50005 , the read request is processed in accordance with the exemplary process set forth in FIG. 6 for step 50005 .
[0051] At step 50006 , when the request is determined to not be a read request, storage system control program 10301 next determines whether the request is a table read request from the management computer 10100 .
[0052] At step 50007 , when the request is a table read request from the management computer 10100 , then the storage system control program 10303 sends the requested file type table 10302 or text reader table 10303 to the management server 10100 .
[0053] At step 50008 , storage system control program 10301 determines whether the request is a table update request from management computer 10100 .
[0054] At step 50009 , when the request is a table update request, then the storage system control program 10301 updates the file type table 10302 and/or text reader table 10303 in accordance with the information received in the table write request.
[0055] At step 50010 , when the request is not one of a write request, a read request, a table read request, or a table update request, the request is not a valid request according to the invention, and can be considered erroneous.
[0056] FIG. 6 illustrates an exemplary flowchart of a process for carrying out a read request according to step 50005 of FIG. 5 .
[0057] At step 60001 , storage system control program 10301 determines whether the sender of the read request is a registered text reader by referring to text reader table 10303 to determine whether the sender's ID is registered as a text reader requestor ID 30301 in the text reader table 10303 .
[0058] At step 60002 , when the sender of the read request has been determined to be a text reader, storage system control program 10301 retrieves the file specified in the read request and extracts the text from the specified file based upon file type. The type of the particular file is determined by referring to the file type table 10302 and matching the file name extension of the specified file with a type listed in the file type table 10302 .
[0059] At step 60003 , storage system control program 10301 returns the extracted text to the requestor instead of returning the entire file.
[0060] At step 60004 , when storage system control program 10301 determines that the requestor of the read request is not a text reader, the specified file is sent to the requestor in a conventional manner.
[0061] Accordingly, from the foregoing, it may be seen that in the first embodiments, by offloading the process of text extraction from the index server to the storage system, the amount of network traffic may be reduced. An interface to access the text is provided without changing from standard NFS (Network File System) protocol. Further, because the text extraction takes place at the storage system rather than at the index server, the load on the index server is also reduced.
Second Embodiments
[0062] In second exemplary embodiments, as illustrated in FIG. 7 , a storage system 70200 storing objects 70222 (i.e., in an object-based storage format) provides extracted text to an index server 70002 or other text reader. As illustrated in FIG. 8 , an object 70222 is a collection of one or more fields 80000 that store information including data content and attributes and other data corresponding to the data content of the object. Each field 80000 includes a field name 80001 , a field attribute 80002 , for example, the MIME type of the field, and a field value 80003 which corresponds to the content data of the object. Each object is identified by an object ID 80004 which is generated by the storage system when an object is stored in the storage system. Typically, an application reads and writes to one or more particular fields 8000 in an object instead of to the whole object. Data written to the fields 8000 becomes persistent if the object is committed to the storage system. Details pertaining to creating and accessing objects are described in the XAM specification incorporated by reference above. In these embodiments, an object may contain one application field 80000 , which contains data content to be indexed and may also contain multiple other fields 80000 , which store management information. Further, while the XAM specification is used as an example in these embodiments, other object-based protocols and specification may be used in other embodiments of the invention.
[0063] According to exemplary embodiments, an administrator is able to specify when the text extraction function extracts text from objects and how the extracted text is maintained in the storage system or accessed by text readers. The storage system of these embodiments also provides a function to export an object to a backup server and a function to extract text from multiple objects specified by a text reader. The administrator also is able to specify whether or not the extracted text is included in an exported object. Computers may access objects and extracted text in the storage system by using an object-accessing interface such as XAM (Extensible Access Method) or other suitable interfaces and protocols.
[0064] FIG. 7 illustrates an example of a hardware and logical configuration in which the second embodiments of the invention may be applied. As illustrated in FIG. 7 , storage system 70200 capable of storing data as objects is coupled to a number of computers over a network, such as a LAN 70003 . The computers include a backup server 70000 , an application server 70001 , an index server 70002 , and a management server 70100 . The storage system 70200 includes a clock 70204 to provide the current time, a CPU 70201 , a memory 70203 and a storage area controller 70220 . Storage area 70221 may be one or more storage mediums, such as HDDs, solid state devices, or the like. A plurality of objects 70222 may be created and stored in storage area 70221 . A storage system control program 70301 similar to that discussed in the first embodiments above is maintained in memory 70203 or other computer readable medium and executed by CPU 70201 for carrying out embodiments of the invention and other storage system functions. Also, a plurality of data structures are maintained in memory 70200 for storing management information, including an update list 70302 , a text reader table 70303 , a default policy 70304 , a field name structure table 70305 , and a text export control flag 70306 .
[0065] Text reader table 70303 may have the same structure as text reader table 30301 illustrated in FIG. 3 . However, in the second embodiments, the text readers (e.g., index server, etc.) are restricted to only accessing fields 80000 containing extracted text. The storage system control program 70301 prevents text readers from accessing the original data of an object 70222 or other parts of the object.
[0066] Text export control flag 70306 contains a value for providing an indication of TRUE or FALSE with respect to text exporting. In these embodiments, TRUE means that if an object is exported to the backup server, the extracted text of fields in the object is also exported. FALSE means that the extracted text is not exported. This control scheme can be applied to other functions which read or write the whole object. For example, similar flags can be used to specify whether or not the extracted text is included in an object if the object or text is replicated to a remote site.
[0067] FIG. 9 illustrates an exemplary data structure of update list 70302 . Update list 70302 contains pointers 90000 to fields of an object. Each pointer 90000 consists of an object ID 90001 and a field name 90002 . The pointers 90000 can be used to direct the storage system control program 70301 to extract text from the listed object field identified in the pointer 90000 .
[0068] FIG. 10 illustrates an exemplary data structure of a field name structure table 70305 to be used for creating field names in an object for extracted text. Field name structure table 70305 defines the structure to be used for creating names of fields which contain extracted text and management information for an application field. Each column contains a prefix of a field name. The field name prefix of extracted text 100001 contains the field name prefix of extracted text. The field name prefix of extraction time 100002 contains the field of time the text is extracted. The field name prefix of extraction policy 100003 contains the field for a management policy for an application. For example, using the structures illustrated in FIG. 10 , if an application has a field whose name is ‘XXX’ in an object, extracted text is stored in a field whose name is ‘.extracted.text.value.XXX’, extraction time is stored in a field whose name is ‘.extracted.text.time.XXX’, and the management policy is stored in a field whose name is ‘.extracted.text.policy.XXX’ in the same object. The details of these policies are described later. In this embodiment, text extracted from a field is stored in one field for simplicity. However, if the results of extraction contain multiple parts, including segments of text or information other than text like layout of text in a document, they can be stored in multiple fields. For example, if text is extracted per page in a document, the text extracted from each page can be stored in an individual field.
[0069] FIG. 11 illustrates the default policy 70304 containing the default value of the management policy which specifies when the function extracts text from objects and how the text is maintained in the storage system. As illustrated in FIG. 11 , examples of policies which may be set as the default policy 70304 are as follows: an ‘on-demand’ policy 110001 , which means that text is extracted when a text reader requests the storage system to send the text; a ‘never-delete’ policy 110002 , which means that text is extracted after an object is written and always held in the storage system with an indefinite retention period; a ‘delete-after-read’ policy 110003 , which means text is extracted after an object is written, and the extracted text is held in the storage system until the extracted text is read by a text reader; and a ‘period’ policy 110004 , which means text is extracted after an object is written and held in the storage system for the specified retention period following the text extraction. The period is specified as a part of the policy, as shown in 110004 . These policies may be contained in an extraction policy field in an object.
[0070] Process Flows
[0071] FIG. 12 illustrates an exemplary overall process flow of carried out by the storage system control program 70301 in these embodiments.
[0072] At step 120000 , storage system control program 70301 initiates two background processes to maintain any extracted text that should be held in the storage system. These processes are a background text extraction process described further with reference to FIG. 13 , and a background text deletion process described further below with reference to FIG. 14 .
[0073] At step 120001 , storage system control program 70301 receives a request from a computer, such as backup server 70000 , application server 70001 , index server 70002 , or management computer 70100 . These embodiments enable two additional requests not discussed above in the first embodiments, namely, an export request and a job request. Accordingly, the request will be one of the following: a write request, which contains an ID of an object, a name of a field to be stored or updated, and the content data to be stored; a read request, which contains an ID of an object and a name of a field to be read; a table read request, which requests reading and return of the management tables; a table update request, which provides new content for updating the management tables; an export request, which requests the export of an object by specifying the ID of the object; and a job request, which contains a job command, as discussed further below. When a request is received, the type of request is determined.
[0074] At step 120002 , storage system control program 70301 determines whether or not the received request is a write request, which contains a name (address) of a file to be stored and the contents (data) of the file to be stored. If the request is a write request, the process goes to step 120003 ; if not, the process goes to step 120004
[0075] At step 120003 , when the request is a write request, the request is typically from a computer such as application server 70001 for updating application files contained in storage system 70200 , or the like. Storage system control program 70301 stores the file data included with the write request in the storage area 70221 .
[0076] At step 120004 , when the request is determined to not be a write request, storage system control program 70301 next determines whether the request is a read request containing a name of a file to be read.
[0077] At step 120005 , the read request is processed in accordance with the exemplary process set forth in FIG. 16 for step 120005 .
[0078] At step 120006 , when the request is determined to not be a read request, storage system control program 70301 next determines whether the request is an export request.
[0079] At step 120007 , when the request is an export request, then the request is processed in accordance with the exemplary process set forth in FIG. 17 for step 120007 .
[0080] At step 120008 , storage system control program 70301 determines whether the request is a job request.
[0081] At step 120009 , when the request is a job request, then the request is processed in accordance with the exemplary process set forth in FIG. 19 for step 120009 .
[0082] At step 120010 , when the request is determined to not be a job request, storage system control program 70301 next determines whether the request is a table read request from the management computer 70100 for reading text reader table 70303 or other data structures 70304 , 70305 , or 70306 .
[0083] At step 120011 , when the request is a table read request from the management computer 70100 , then the storage system control program 70303 sends the requested tables to the management server 70100 .
[0084] At step 120012 , storage system control program 70301 determines whether the request is a table update request from management computer 70100 .
[0085] At step 120013 , when the request is a table update request, then the storage system control program 70301 updates the specified tables, such as text reader table 70303 or other data structures 70304 , 70305 , or 70306 in accordance with the information received in the table write request.
[0086] At step 120014 , when the request is not one of a write request, a read request, an export request, a job request, a table read request, or a table update request, the request is not a valid request according to the invention, and can be considered erroneous.
[0087] FIG. 13 illustrates an exemplary process flow of the background text extraction process. The background text extraction process extracts text from fields 80000 in objects 70222 stored in storage system 70203 if a management policy specifies for the text to be extracted and held in the storage system. One of policies 11001 through 11004 may be specified by a user, or if no policy is specified, then a default policy in effect for the storage system is applied.
[0088] At step 130001 , storage system control program 70301 selects one entry from the update list 70302 for processing. Update list 70302 is a list of fields of objects stored in a storage system from which the text needs to be extracted. In other words, when storage system 70200 needs to extract text of a field that has not yet been extracted, a pointer to the field is added to update list 70302 so that the background text extraction process of FIG. 13 will subsequently extract the text from the field and store the extracted text in the storage system 70200 .
[0089] At step 130002 , storage system control program 70301 extracts text from the field specified in the update list 70302 based on the data type (e.g., MIME type) recorded in the field attribute 80002 .
[0090] At step 130003 , storage system control program 70301 stores the extracted text to a new field in the specified object. The name of the field is determined by the combination of the specified field name and the prefix 100001 as defined in field name structure table 70305 .
[0091] At step 130004 , storage system control program 70301 creates another field in the object to store the time at which the text was extracted and names the field in accordance with field name prefix of extraction time 100002 of field name structure table 70305 .
[0092] At step 130005 , storage system control program 70301 records the time at which the text was extracted in the field created in step 130004 .
[0093] At step 130006 , storage system control program 70301 removes the entry from the update list 70302 and returns to step 130001 .
[0094] FIG. 14 illustrates an exemplary process flow of the background text deletion process, which deletes extracted text when the specified period for which it was to be held has expired. Basically, the background text deletion process examines each object in the storage system, one-by-one, to determine whether the particular object has extracted text that is due to be deleted according to a corresponding policy.
[0095] At step 140001 , storage system control program 70301 selects one object from storage area 70221 for processing.
[0096] At step 140002 , storage system control program 70301 examines the selected object to determine whether an extraction time field exists in the object. When there is no extraction time field in the object, then there is no extracted text to be deleted in the object, and the process goes back to step 14001 to examine the next object.
[0097] At step 140003 , when an extraction time field is located in the object, then storage system control program 70301 determines whether there is a management policy specified for the selected field. If there is a specified management policy for the selected field, the process goes to step 140004 ; if the field does not include a specified policy, the process goes step 140005 to check the default policy.
[0098] At step 140004 , when a management policy is specified, storage system control program 70301 determines if the specified management policy specifies a time period to maintain the extracted text in the storage system. If the specified policy does not specify a time period to hold the text, the field does not have to be processed further and the process goes to step 140001 to process the next object.
[0099] At step 140005 , storage system control program 70301 determines whether the default policy currently in effect in the storage system 70200 specifies a period to hold extracted text. If so, the process goes to step 140006 ; if not, the process goes to step 140001 to process the next object.
[0100] At step 140006 , storage system control program 70301 determines whether the specified time period to hold the extracted text has expired. If so, the process goes to step 140007 ; if not, the process goes to step 140001 to process the next object.
[0101] At step 140007 , storage system control program deletes the extracted text stored in the field to release storage area and increase usable capacity in the storage system 70200 .
[0102] At step 140008 , storage system control program 70301 deletes the field that stored the extraction time of the deleted text. These steps are repeated for all application fields in objects stored in the storage system 70200 .
[0103] FIG. 15 illustrates an exemplary process flow carried out when a write request is received at step 120003 of FIG. 12 . This may occur, for example, when an application server writes updated data to one of the objects in the storage system. After an object is updated, any extracted text stored with the object is no longer valid, and needs to be deleted. Further if the policy for the object specifies that extracted text should be created and stored in the object, then a pointer to the object needs to be placed on the update list to have the text of the updated object extracted according to the policy.
[0104] At step 150001 , storage system control program 70301 determines whether the sender of the write request is a registered text reader (i.e., a designated extracted data receiver) by referring to text reader table 70303 to determine whether the sender's ID is registered as a text reader requestor ID 30301 in the text reader table 70303 . If so, the process goes to step 150005 to process as an error to prevent a text reader from writing an object; if not, the process goes to step 150002 .
[0105] At step 150002 , storage system control program 70301 determines whether a policy field exists for the object that is the target of the write request.
[0106] At step 150003 , when a policy field exists for the object, storage system control program 70301 determines whether the policy is “on-demand”. If so, an “on-demand” policy means that extracted text is not stored in the storage system for this object, but instead is only created when a text reader requests the extracted text.
[0107] At step 150004 , when there is no policy field for the object, storage system control program 70301 determines whether the default policy is “on-demand”.
[0108] At step 150005 , storage system control program 70301 issues an error to prevent a text reader from writing to an object.
[0109] At step 150006 , storage system control program 70301 adds a pointer to the update list 70302 to have the extracted text in the target object updated by the background text extraction process of storage system control program 70301 .
[0110] At step 150007 , storage system control program 70301 determines whether a field of extraction time exists in the target object.
[0111] At step 150008 , storage system control program 70301 deletes the field that stored the extraction time.
[0112] At step 150009 , storage system control program 70301 determines whether a field of old extracted text exists in the target object.
[0113] At step 150010 , storage system control program 70301 deletes the field that stored the extracted text.
[0114] At step 150011 , storage system control program 70301 writes the specified data to the target object in accordance with the write request. If the written object is a new object, a new object ID is assigned by the storage system control program and returned to the requestor.
[0115] FIG. 16 illustrates an exemplary process flow for carrying out a read request in step 120005 of FIG. 12 . If the specified field to be read is not a field of extracted text, then the storage system control program checks whether or not the requestor is a text reader. If the requestor is a text reader, it cannot access any information other than extracted text.
[0116] At step 160000 , storage system control program 70301 determines whether the specified field to be read from the target object is a field of extracted text.
[0117] At step 160001 , when the specified field to be read from the target object is not a field of extracted text, storage system control program 70301 determines whether the sender of the read request is a registered text reader by referring to text reader table 70303 to determine whether the sender's ID is registered as a text reader requestor ID 30301 in the text reader table 70303 . If so, the process goes to step 160003 to process as an error to prevent a text reader from reading text that is not extracted text; if not, the process goes to step 160002 .
[0118] At step 160002 , storage system control program 70301 returns the specified field to the requestor in response to the read request.
[0119] At step 160003 , storage system control program 70301 issues an error to prevent a text reader from reading a field that is not extracted text.
[0120] At step 160004 , when the specified field is a field of extracted text, storage system control program 70301 determines whether a field of extraction time exists in the object that is the target of the read request. If so, this indicates that extracted text is stored in the object.
[0121] At step 160005 , when a field of extraction time exists in the object, then storage system control program 70301 returns to specify the extracted text field to the requester of the read request.
[0122] At step 160006 , storage system control program 70301 determines whether the policy for the extracted text is “delete-after-read”.
[0123] At step 160007 , storage system control program 70301 deletes the field of the extracted text in the target object.
[0124] At step 160008 , storage system control program 70301 deletes the field that stored the extraction time.
[0125] At step 160009 , on the other hand, when a field of extraction time does not exists in step 160004 , the object storage system control program 70301 extracts text from the specified field in the target object.
[0126] At step 160010 , storage system control program 70301 determines whether the policy associated with the object is on-demand or delete-after-read. If so, the process gets to step 160014 , and the text is sent to the requestor but not stored in the storage system. If not, then the extracted text will also be stored in the object.
[0127] At step 160011 , storage system control program 70301 creates a field for storing the extraction time of the extracted text.
[0128] At step 160012 , storage system control program 70301 records the time at which the text was extracted in to the field of the extraction time created in step 160011 .
[0129] At step 160013 , storage system control program 70301 creates a field for storing the extracted text, and stores the extracted text therein.
[0130] At step 160011 , storage system control program 70301 returns the extracted text to the requester of the read request.
[0131] FIG. 17 illustrates an exemplary process flow for carrying out an export request at step 120007 of FIG. 12 . In these embodiments, an export request can be sent from the backup server 70000 to obtain a package which contains information of the whole object instead of individual fields of the object.
[0132] At step 170001 , storage system control program 70301 determines whether the sender of the export request is a registered text reader by referring to text reader table 70303 to determine whether the sender's ID is registered as a text reader requestor ID 30301 in the text reader table 70303 (i.e., a known extracted data receiver). If so, the process goes to step 170002 to process as an error to prevent a text reader from requesting export of an object; if not, the process goes to step 170003 .
[0133] At step 170002 , storage system control program 70301 issues an error to prevent a text reader from requesting export of an object.
[0134] At step 170003 , when it has been determined that the requester is not a text reader, storage system control program 70301 creates an export package for the specified object.
[0135] At step 170004 , during creation of the export package, storage system control program 70301 includes all fields contained in the object in the export package except for any field of extraction time or field of extracted text.
[0136] At step 170005 , storage system control program 70301 determines whether the text export control flag is set to equal “TRUE”.
[0137] At step 170006 , when the text export control flag is set to equal ‘TRUE’ storage system control program 70301 also adds any fields of extraction time and extracted text to the export package. Otherwise, when the text export control flag is set to FALSE the extraction time and extracted text fields are withheld from being included in the export package.
[0138] At step 170007 , storage system control program 70301 returns the export package to the requester of the export request.
[0139] FIG. 18 illustrates an exemplary data structure of job objects in the storage system, which can be used for extracting text from a number of objects, instead of only one, via a single command. For example, by issuing a job request, a requestor can request all extracted text in the storage system using a single job request. In these embodiments, a job object 180001 contains a field specifying what processing actions should be taken by the storage system 70200 . In an exemplary instance the job object is identified by its name 180002 , such as “Job command”; type 180003 which specifies the type of extracted data, e.g., “text/plain”; and value 180004 , which contains lines of text. The first line in the value field 180004 specifies the type of job. In the illustrated embodiment, the type of job is indicated by the text string of ‘Command=“extract text”’. Then, the lines that follow specify the fields where the storage system control program will extract text. Each line contains object IDs and field names from which text is to be extracted. Other fields 180011 in the job object are created by the storage system control program and contain the extracted text for the specified fields specify by the field 180001 . Each field 180011 in the job object has a name comprising the combination of a prefix, object ID, and field name 180012 and the type of extracted text 180013 . The extracted text is contained in a specified field 180014 .
[0140] FIG. 19 illustrates an exemplary process flow for carrying out processing of a job request in step 120014 of FIG. 12 .
[0141] At step 190001 , storage system control program 70301 verifies the format of the “job command” field 180002 of a received job request 180001 .
[0142] At step 190002 , storage system control program 70301 determines whether the format of the “job command” field 180002 is a valid.
[0143] At step 190003 , storage system control program 70301 stores the object in the storage area and returns a new ID to the requestor, if necessary.
[0144] At step 190004 , storage system control program 70301 initiates a background job process, the details of which are set forth in FIG. 20 .
[0145] At step 190005 , if the format of the “job command” field 180002 is invalid, the job command is considered erroneous.
[0146] FIG. 20 illustrates an exemplary process flow of the background job process carried out in step 190004 of FIG. 19 .
[0147] At step 200001 , storage system control program 70301 selects one field specified in text area 180004 of the ‘job command’ field in the job object.
[0148] At step 200002 , storage system control program 70301 creates a new field in the job object to store the text extracted from the selected field.
[0149] At step 200003 , storage system control program 70301 obtains extracted text, as described, for example, in steps 160000 - 160014 of FIG. 16 , and stores the extracted text into the new field created in step 200002 .
[0150] At step 200004 , storage system control program 70301 determines whether all fields in the job object have been processed. If not, steps 200001 - 200003 are repeated until all fields specified in the job object have been processed. The requester can obtain the extracted text by reading fields in the job object stored in the storage system.
[0151] In these embodiments, by specifying when the text extraction function extracts text from objects and by specifying how the extracted text is maintained in the storage system, an administrator is able to adjust the balance between the performance of a indexing process and the resource consumption of the storage system. In addition, the administrator is able to specify whether or not the extracted text is included in exported objects. Furthermore, according to exemplary embodiments, extracted text can be obtained from multiple fields of a number of different objects by sending a single job request, which reduces the number of communications between the index server and the storage system. Also, the requestor does not need to wait until the storage system finishes extracting text because the job request can be processed asynchronously by background processes within the storage system.
[0152] In addition, embodiments of the invention can also be easily applied to process data other than text. For example, the storage system control program 70301 can create a small thumbnail image from a larger image stored as a field in an object. In this case, instead of the function to extract text, the storage system control program has a function to convert a large image to a smaller fixed-size image, i.e., a thumbnail image. The process to create/store/access a thumbnail of an image file is executed by process flows similar to those illustrated in the embodiments for extracting text.
[0153] Accordingly, from the foregoing, it will be apparent that embodiments of the invention provide a storage system having a function to extract text or other data from a file or object in order to offload the process of extraction to the storage system and also to reduce network traffic. The method used for extraction depends on the original file type. Furthermore, the storage system may have a management interface that can be used for specifying when the text is extracted and how the text is maintained in the storage system. The storage system also may have a management interface to control how other storage functions are applied to the extracted text.
[0154] The method and system reduce network traffic and improve the performance and efficiency of the indexing process. The interface to retrieve extracted text can be implemented by using standard interfaces such as NFS or XAM. The management interface provides measures to adjust the balance between the indexing process performance and the storage system's consumption of resources.
[0155] Of course, the system configurations illustrated in FIGS. 1 and 7 are purely exemplary of information systems in which the present invention may be implemented, and the invention is not limited by these embodiments to a particular hardware or logical configuration. The computers and storage systems implementing the embodiments can also have known I/O devices (e.g., CD and DVD drives, floppy disk drives, hard drives, etc.) which can store and read the modules, programs and data structures used to implement the above-described invention. These modules, programs and data structures can be encoded on such computer-readable media. For example, the data structures of the various embodiments can be stored on computer-readable media independently of one or more computer-readable media on which the programs reside. The components of the system can be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include local area networks, wide area networks, e.g., the Internet, wireless networks, storage area networks, and the like.
[0156] In the description, numerous details are set forth for purposes of explanation in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that not all of these specific details are required in order to practice the present invention. It is also noted that the invention may be described as a process, which is usually depicted as a flowchart, a flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be re-arranged.
[0157] As is known in the art, the operations described above can be performed by hardware, software, or some combination of software and hardware. Various aspects of embodiments of the invention may be implemented using circuits and logic devices (hardware), while other aspects may be implemented using instructions stored on a machine-readable medium (software), which if executed by a processor, would cause the processor to perform a method to carry out embodiments of the invention. Furthermore, some embodiments of the invention may be performed solely in hardware, whereas other embodiments may be performed solely in software. Moreover, the various functions described can be performed in a single unit, or can be spread across a number of components in any number of ways. When performed by software, the methods may be executed by a processor, such as a general purpose computer, based on instructions stored on a computer-readable medium. If desired, the instructions can be stored on the medium in a compressed and/or encrypted format.
[0158] From the foregoing, it will be apparent that the invention provides methods, apparatuses, systems and programs stored on computer readable media for reducing network traffic and the workload of servers by offloading a portion of the information processing task from the servers to the storage system. Additionally, while specific embodiments have been illustrated and described in this specification, those of ordinary skill in the art appreciate that any arrangement that is calculated to achieve the same purpose may be substituted for the specific embodiments disclosed herein. This disclosure is intended to cover any and all adaptations or variations of the present invention, and it is to be understood that the terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with the established doctrines of claim interpretation, along with the full range of equivalents to which such claims are entitled.
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In a networked information system, a portion of the information processing is offloaded from servers to a storage system to reduce network traffic and conserve server resources. The information system includes a storage system storing files or objects and having a function which automatically extracts portions of text from the files and transmits the extracted text to the servers. The text extraction is responsive to file requests from the servers. The extracted text and files are stored on the storage system, decreasing the need to send entire files across the network. Thus, by transmitting smaller extracted text data instead of entire files over the network, network performance can be increased through the reduction of traffic. Additionally, the processing strain on physical resources of the servers can be reduced by extracting the text at the storage system rather than at the servers.
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CLAIM OF PRIORITY
The following application is a continuation of U.S. patent application Ser. No. 12/646,899, which was filed on Dec. 23, 2009, now U.S. Pat. No. 7,963,885 which claims priority to U.S. Provisional Patent Application No. 61/140,358, filed Dec. 23, 2008, the complete contents of each of which are incorporated by reference herein.
BACKGROUND
1. Field of the Invention
The invention relates generally to athletic training devices and more particularly to an erratically and rapidly moving device configured such that in order to be captured an athlete must exhibit a required level of speed and agility.
2. Background
Speed and agility are critical in numerous sports and other activities. However, motion in predictable patterns and/or on agility courses can be seen in advance and can be quickly learned by athletes. Existing training systems include stationary courses such as ladder drills, running through tires, or basketball “suicide” drills. Further systems exist, such as targeted chasing systems wherein an athlete moves as rapidly as possible towards a selected one of a set of illuminable lights. However, the selectively illuminable lights are stationary and thus the athlete can quickly adapt and/or anticipate the illumination sequence and/or memorize the locations of the fixed number of illuminable lights. In actual play, however, the motion may be unpredictable, and athletes must be able to still move quickly.
What is needed is a system that provides unpredictable speed and agility training for athletes.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts a perspective view of the exterior of an embodiment of the present device.
FIG. 1 a depicts a bottom view of the exterior of an embodiment of the present device.
FIG. 1 b depicts a top view of the interior of an embodiment of the present device.
FIG. 2 depicts a detail perspective view of an embodiment of a shut-off device in the present device.
FIG. 3 depicts another embodiment of the present device further comprising a remote-control unit.
FIG. 4 depicts a schematic diagram of one embodiment of the present device.
FIG. 5 depicts a bottom view of another embodiment of the present device that can operate in an aquatic environment.
FIG. 6 depicts a side view of an alternative embodiment of the present device.
DETAILED DESCRIPTION
FIGS. 1-1B depict various views of embodiments of the present device. FIG. 1 depicts a perspective exterior view of one embodiment of the present device. In some embodiments, a housing 102 can comprise a plurality of sections 104 , which can be coupled together and substantially vertically arranged. In such embodiments, sections 104 can move independently of each other, or in coordinated movements with each other. However, in other embodiments, a housing 102 can comprise a single hollow member. As shown in FIG. 1 , a housing 102 can be substantially circular in shape, but in other embodiments can have any other known and/or convenient geometry. In some embodiments, a housing 102 can be made of a resilient plastic, polymer, polycarbonate, metal, alloy, or any other known and/or convenient material. As shown in FIG. 1 , a housing 102 can be coupled with a time mechanism 120 , such as but not limited to, a timer, stopwatch, clock, and/or any other known and/or convenient mechanism for timing a user and/or displaying time.
As shown in FIG. 1 a, a plurality of moving agencies 106 can be coupled with a housing 102 . Moving agencies 106 can be wheels, casters, bearings, or any other known and/or convenient device. In some embodiments, moving agencies 106 can have a rotational range of motion of 360 degrees, or any other known and/or convenient range. As shown in FIG. 1 a , moving agencies 106 can be coupled with a housing 102 at points on the underside of and, in some embodiments, substantially proximal to the periphery of a housing 102 . However, in other embodiments, moving agencies 106 can be coupled with a housing 102 in any known and/or convenient locations.
In some embodiments, one of the moving agencies 106 can be configured to drive a housing 102 in any desired direction. In some embodiments, the moving agencies 106 can be configured to randomly drive a housing 102 in any direction. In alternate embodiments, more than one of the moving agencies 106 can be configured to drive the housing 102 either separately and/or simultaneously.
In some embodiments, a switch 108 can be located on the top surface of a housing 102 , but in other embodiments can be located on a side or underside surface. An on-off switch 108 can be adapted to selectively control the operation of the moving agencies 106 , drive system 114 , and/or power the device on and off.
In the embodiment depicted in FIG. 1 , a housing 102 can include an opening 110 adapted to receive a shut-off unit 112 . In some embodiments, an opening 110 can be substantially circular, but in other embodiments can have any other known and/or convenient geometry. In the embodiment depicted in FIG. 1 , a shut-off unit 112 can be selectively and operatively mated with an opening 110 such that a device will not be propelled when a shut-off unit 112 is not mated with an opening 110 . A shut-off unit 112 can have a substantially cylindrical shape, as shown in FIG. 1 , but in other embodiments can have any other known and/or convenient geometry. In some embodiments a shut-off unit 112 can be magnetized in a desired configuration and an opening 110 can include a magnetic reader such that the pattern and/or random sequence can be defined by the magnetic configuration of a shut-off unit 112 and/or the speed of insertion of a shut-off unit 112 into an opening 110 .
As shown in FIG. 1 a, a drive device 114 can be coupled to a drive agency 116 and coupled to a power supply 118 . In some embodiments, a power supply 118 can be a battery, but in other embodiments can be a solar cell or any other known and/or convenient device. In some embodiments, a drive device 114 can be a motor, but in other embodiments can be any other known and/or convenient mechanism. In the embodiment shown in FIG. 1 a , a drive agency 116 can be at least one wheel, but in other embodiments can be a caster, bearing, or any other known and/or convenient device.
In alternate embodiments, a drive device 114 can further comprise a pump and/or turbine system. In such embodiments, a drive agency 116 can be a nozzle, propeller, or any other known and/or convenient device to produce thrust. In such embodiments, moving agencies 106 can be fins or any other known and/or convenient device.
FIG. 2 depicts a detail view of one embodiment of a shut-off device 112 . As shown in FIG. 2 , a shut-off device 112 can further comprise a visual enhancement device 202 that can be a flag, two-dimensional or three-dimensional graphic, or any other known and/or convenient device. A shut-off unit 112 can further comprise a control mechanism 204 that can control stop-and-go motion of the device. In some embodiments, a control mechanism 204 can comprise an electrical coupling 206 that when disrupted causes the device to cease motion. In some embodiments, an electrical coupling 206 can further comprise magnetic components. However, in other embodiments, any other known and/or convenient control mechanism can be used.
In some embodiments, as shown in FIG. 2 , a shut-off unit 112 can further comprise a motion-control device 208 , which can further comprise at least one magnet 210 . In some embodiments, a motion-control device 208 can be a magnetostatic device with said at least one magnet 210 capable of producing an electrical current that can be used to create a seed value for input into a random-pattern generator. A reader 212 can be located in an opening 110 such that a pattern and/or random sequence can be defined by a magnetic configuration of at least one magnet 210 on a shut-off unit 112 and/or the speed of insertion of a shut-off unit into an opening 110 .
FIG. 3 depicts another embodiment of the present device, further comprising a remote-control unit 302 . A remote-control unit 302 can operate via a wireless connection or any other known and/or convenient mechanism.
FIG. 4 depicts an electro-mechanical schematic of one embodiment of the present device. A drive-control circuit 402 and a directional-control circuit 404 can both be connected to a central processing unit (CPU) 406 . A CPU 406 can be connected to an input device/receiver 408 , which can be connected to a power supply 410 . A motion-control device 208 can be connected to an input device/receiver 408 via an op-amp circuit 412 . A remote-control 302 can also provide input to an input device/receiver 408 via a wireless connection or any other known and/or convenient method. In some embodiments, a CPU 406 can also be capable of collecting motion information from the device and connecting to an external personal computer to download such information. Further, in some alternate embodiments, a device can include a timing mechanism 120 (as shown in FIG. 1 ) to record and optionally display chronological information regarding motion of the device.
In a drive-control circuit 402 , a power supply 118 can be connected to a shut-off device 112 , an on-off switch 108 , a drive device 114 , and a resistor 414 , In some embodiments, a drive device 114 can be a motor, but in other embodiments can be any other known and/or convenient device. As shown in FIG. 2 , a power supply 118 can be a variable power supply, or in other embodiments can be any other known and/or convenient device.
In a directional-control circuit 404 , a power supply 416 can be connected to a resistor 418 and a drive device 420 . In some embodiments, a drive device 420 can be a motor, but in other embodiments can be any other known and/or convenient device.
A CPU 406 can be connected to a power supply 118 for a drive circuit 402 via an amplifier 422 , and also to a power supply 416 for a directional-control circuit 404 via and amplifier 242 . In such embodiments, a CPU can, therefore, provide input to control a drive circuit 402 and a directional-control circuit 404 .
A remote-control unit 302 can provide input concerning direction, speed, on/off status, or any other known and/or desired parameters to an input device/receiver 408 .
As shown in FIG. 4 , a motion-control device 208 can, in some embodiments, be incorporated into a shut-off device 112 . A magnet 210 on a shut-off device 112 can, when in motion, produce a current that can be read by a reader 212 . An induced current can vary depending upon the orientation of magnets 210 in relation to readers 212 and the speed of magnets 210 in moving past readers 212 . In embodiments having multiple magnets 210 and readers 212 , as shown in FIG. 4 , the electrical signals resulting from an induced current can be summed in an op-amp circuit 412 and sent to a CPU 406 via an input device/receiver 408 . A CPU 406 can process these electrical signals to provide control information to a drive-control circuit 402 and a directional-control circuit 404 by using electrical signals to establish a seed value for a random-number generator in a CPU 406 . In some embodiments, a random number generator can translate an electrical signal into numerical values. In such embodiments, a numerical value can be parsed into separate values, each of which can be used to control speed and direction. For example, in some embodiments, a numerical value can have a plurality of digits. One or more digits can correspond to a seed value for speed control, one or more other digits can correspond to a seed value for the control time period, and at least one remaining digit can correspond to a seed value for directional control.
FIG. 5 depicts another embodiment of the present device that can operate in an aquatic environment. Such embodiments can further comprise a flotation device 502 , which can be located circumferentially around a housing 102 , or in any other known and/or convenient position. In some embodiments, a housing 102 can be comprised of a buoyant material.
FIG. 6 depicts a side view of another embodiment of the present device. In some embodiments, a housing 102 can include extension arms 602 adapted to reduce the likelihood of overturning the device. Moreover, in some embodiments the shut-off unit 112 can be coupled with an object 604 . In some embodiments, an object 604 can have the shape of a rabbit and/or any desired shape. In some embodiments, a shut-off unit 112 can include a depression 216 that can mate with a protrusion at the base of the opening 110 . In some embodiments, the protrusion can be coupled with a rotational motor 608 such that as the motor rotates, both the drive agency 116 and the object 604 can rotate in unison. In alternate embodiments, the object 604 and drive agency 116 can move and/or rotate independently.
In use, a user can turn a switch 108 to the “on” position and insert a shut-off unit 112 into an opening 110 . The present device can then begin to move about and be chased by a person, who could have the goal of overtaking the device and removing the shut-off unit 112 , which would cause the device to stop moving. A person can also chase the device without the goal of removing a shut-off unit 112 , but rather to follow a prescribed pattern. In some embodiments, motion of the device can be determined by a magnetostatic device that produces a random movement pattern. In other embodiments, motion can be controlled by a remote user via a remote-control unit 302 . Either way, the erratic movement of the present device can require the person chasing the device to change motion quickly, and, therefore, develop speed and agility.
Although the method has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the method as described and hereinafter claimed is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.
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An athletic training device to develop speed and agility. A robot can be programmed or remote controlled to move in an erratic manner so that it can be chased by an athlete. An on-board shut-off unit stops the device when it is removed by the athlete chasing the device.
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FIELD OF THE INVENTION
This invention is an improved method and apparatus for application of an elastic material to articles of manufacture. In a preferred application it may be used for attaching elastic strips to localized areas of clothing such as disposable undergarments or diapers.
BACKGROUND OF THE INVENTION
Methods for applying elastic to clothing and similar articles are well known in the art. The elastic is normally in the form of a ribbon or tape and is used to provide snug fits around areas such as waist or leg openings. For many years this elastic was attached by hand sewing. With the advent of disposable one-time-use garments the labor cost of hand sewing became prohibitive and other means of application had to be sought. Several patents can be cited as exemplary of the development of the art up to the time of the present invention.
Goujon et al., U.S. Pat. No. 3,488,778, show a disposable panty in which the elastic is apparently applied by glue bonding, although no specific means of accomplishing this is shown.
Butter, U.S. Pat. No. 3,560,292, shows a similar garment in which the elastic is "spot-welded" to the base textile. Again, he does not disclose an apparatus for accomplishing this result at high speed.
Burger, in U.S. Pat. No. 3,663,962, teaches a method of continuously applying longitudinal strips of stretched elastic to a panty-type garment by sewing or adhesive bonding. He deals with the problem of keeping the elastic flat on the material by essentially freeing it in its stretched state during application. This process is further described in U.S. Pat. No. 3,694,815 to the same inventor.
Bourgeois, U.S. Pat. No. 3,828,367, uses an adhesive bonding system to place stretched elastic along the waistline and leg openings of disposable panties. The elastic is applied continuously and severed when each article is trimmed from the continuous sheet of nonwoven material. While this achieves the desired result at the waistline, it leaves a strip of tensioned elastic across the front and rear transverse margins of the crotch or gusset sections. These are areas where elastic is not desirable either from functional or wearer comfort standpoints.
Buell, U.S. Pat. No. 4,081,301, shows in detail a commercially practical system of applying elastic to the leg openings of disposable diapers. Buell has faced two vexiing problems. He has avoided the complexity of applying the elastic in a curvilinear fashion and has substituted a design which allows straight line application. He has also found one solution to the problems of selectively placing the elastic where it is functionally desirable without also having it in places where it is unwanted, such as in Bourgeois.
A diaper made by the Buell process is shown in his patent U.S. Pat. No. 3,860,003. Here the elastic is functional only around the lower two-thirds of the leg opening. This, of course, is the region where leakage is most likely to occur.
One commonn feature noted in all of these patents is that it is easier to apply the elastic in an uninterrupted linear manner. By uninterrupted is meant in a continuous strand for the full length of the individual article. As seen in Bourgeois this often puts elastic where it is not wanted. Buell deals with this by adhesively bonding the elastic only in the area in which it is functionally desired, even though the tensioned elastic applied is equivalent to the full article length. The elastic strands are severed when the individual diapers are cut from the continuous assembly. This causes each end to relax to the unstretched length. These ends remain present but they serve no useful purpose. However, they tend to be somewhat unsightly from the user standpoint and waste about 20 percent of the relatively expensive elastic ribbon.
It is thus clear the art has not developed fully satisfactory methods for applying tensioned elastic at high speed to specified areas of articles, where such areas are less than the full length or width of the article.
SUMMARY OF THE INVENTION
The present invention is a method and apparatus for applying elastic units to discrete areas of articles when such areas may be of shorter linear dimension than the length of the article itself, as measured along the axis of the elastic. The invention also represents an advance in the art in that essentially all of the elastic is functional when applied to an area of such shorter linear dimension.
The above results are accomplished by a method in which a strip of tensioned elastic material from a supply source is sequentially grasped between two clamping means, then severed from the main source of elastic adjacent to the second clamping means. The elastic unit thus created is held by the clamps until it is applied to the article, or some component of the article, whereupon it is released by the clamps. The bond between the elastic and the article may be achieved by stitching, spot welding, or by the use of an adhesive. In the latter case this can be applied continuously or intermittently to either the elastic unit or the the appropriate area of the article or component to which the elastic unit will later be applied.
In its preferred form the elastic units are bonded by a continuous layer of adhesive applied to all of the elastic except the short terminal portions held in the clamps. Normally, at least 90 percent of the elastic, measured in its untensioned state, will be functionally bonded to the article. More typically, elastic will be about 95% utilized.
The method is particularly well suited for the production of elastic leg disposable diapers. It is usually most convenient to apply the tensioned elastic units to the plastic backing film prior to assembly of the diapers. The film can itself be held in tension through the assembly process to prevent puckering by the elastic. The method is especially well adapted to apply the elastic units to the leg opening area of the diapers with a minimum of waste. The appearance is also improved since there are essentially no loose ends on the elastic strips.
A preferred version of the method uses a plurality of elastic applicator modules that sequentially apply the elastic units to the articles in a repeating cycle. This can most conveniently be done when one surface of the modules defines the periphery of a wheel-like applicator unit.
In one version of the method the elastic material is first grasped by the clamping means when they are separated by a distance equivalent to the full length of the article. The clamping means are later moved closer together to define the ultimate length of the elastic unit. This movement is more simply controlled when one of the clamping means is fixed and one movable. When a plurality of modules is used, the movable clamping means of one module will be positioned next to the fixed clamping means of an adjacent module at the point where the incoming elastic is grasped. Both clamping means will grasp the elastic material essentially simultaneously, whereupon the severing means will act between them to create the elastic unit. The movable clamping means will then be positioned to the desired relationship with the fixed clamping means of its own module prior to application of the elastic unit to the article.
Apparatus for carrying out the present method is shown in the detailed description of the invention.
It is an object of this invention to provide an improved method and apparatus for applying elastic material to articles such as wearing apparel.
It is a further object to provide a method and apparatus for applying tensioned elastic to specific means of articles when such areas are of shorter linear dimension than the length of the article.
It is another object to provide a method and apparatus for applying tensioned elastic to specific areas of articles with maximum efficiency of the elastic material.
It is yet an object to provide a disposable diaper of improved appearance.
These and other objects will become evident on reference to the following detailed description and figures.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation, partially cut away, showing the elastic applicator in position on a line manufacturing disposable diapers.
FIG. 2 is an isometric view of a typical diaper having an elastic ribbon applied near the margins of the leg areas. The diaper is shown in tension as it would be during much of the manufacturing operation.
FIG. 3 is an isometric view of the diaper shown in the previous figure with the tension relaxed.
FIG. 4 is a partially cut away transverse vertical section of the elastic applicator at 90° to the representation of FIG. 1, taken through Section 1--1 of FIG. 16.
FIG. 5 is a detailed isometric representation spanning two modules of the elastic applicator unit in which the movable clamp of one module is shown moving toward its resting position.
FIG. 6 is partial plan view of the modules shown in FIG. 5.
FIG. 7 is a detailed isometric view spanning two modules in which the movable clamp of one module is shown adjacent to the fixed clamp of the adjacent module with both clamps being in position to seize an incoming strip of elastic.
FIG. 8 is a partial plan view of the clamps shown in FIG. 7.
FIG. 9 is a fragmentary side elevation showing detail of one fixed clamp and its associated elastic severing unit.
FIG. 10 is a fragmentary isometric view of the fixed clamp in position to receive the incoming elastic ribbon.
FIG. 11 is a fragmentary transverse elevation of the representation shown in FIG. 10 taken along Section 11--11 of FIG. 9.
FIG. 12 is a fragmentary isometric view of the fixed clamp after the clamp has grasped the elastic tape, but before the tape has been severed. This figure is also taken along Section 11--11 of FIG. 9.
FIG. 13 is a transverse elevation representation of the view shown in FIG. 12.
FIG. 14 is similar to the preceeding isometric views. Here the elastic has been severed to create an individual unit of elastic.
FIG. 15 is a transverse elevation view of FIG. 14 taken along Section 11--11 of FIG. 9.
FIG. 16 is a diagrammatic side elevation view in which the total sequence of operation of the individual elastic application units can be more clearly represented.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to FIG. 1, the elastic applicator is generally indicated at 2. It is shown here as part of a diaper manufacturing line, partially shown at 3. The elastic applicator is on a frame 4, here mounted on rollers 5 so that it can be readily moved in or out of the line depending on the type of diaper being manufactured. The application comprises a main rotor body 6 and a series of elastic clamping means 8 located around the periphery. The unit shown contains six elastic applicator modules. Each module consists of a movable clamp, generally shown at 10, and a fixed clamp, generally shown at 12. The clamps at 10 and 12 are not members of the same module. Clamp 12 defines the trailing end of an earlier module and clamp 10 defines the leading end of a later module. The clamps are caused to operate by cams 14 and 15. The outside cam 14 controls the position of the movable clamp. The inner cam 15 controls the opening and closing sequence of both clamps and also controls the severing of individual elastic tape units. Cam follower 16 operates through connecting rod 18 to control the position of the movable clamp. Cam follower 17 operates through connecting rod 20 to control the opening and closing sequence of the clamps and the timing of the severing means.
The elastic material, in this case shown as ribbons or tapes 23, 23, is drawn from supply 24 over friction rollers 25 which cause the tape to be tensioned as it is grasped by the clamps 8. As will be described later, the elastic is severed from the main body of tape by a severing knife to create individual elastic units 26. As the rotor body of the applicator turns, the elastic unit passes adhesive applicator 28 which applies either a continuous or intermittent line of adhesive on the elastic substance. Very typically this adhesive will be a hot melt or heat activatable type which has some flexibility at room temperature. In the illustrations shown, an impervious film 30, typically made of polyethylene, is drawn from supply roll 32 under brake roll 33 and over idler roll 34. The individual elastic units 26, now coated with adhesive, are mated to the plastic film under pressure roll 35. They are released by the clamps and carried thenceforth bonded to the plastic film, as at 36. The plastic film is normally maintained under tension when the elastic is applied in order to prevent puckering. The plastic film likewise must be maintained under adequate tensin until the individual articles, in this case diapers, are assembled and until they are severed near the end of the operation. It is within the scope of the invention to apply adhesive to the appropriate areas of the article, rather than the elastic, although this is not generally preferred.
The elastic may be applied to any appropriate article. Typically it will be a garment and in the illustrations shown the article is a disposable baby diaper. The portion of the diaper making machine represented is mounted on frame 39. This includes a roll 40 around which is passed an endless belt 42. The plastic backing film containing the individual elastic units passes around roll 40 where it is supported on the endless belt. Individual pre-cut absorbent pads 44 are laid on the plastic backing film as it passes under assembly roll 48, which imposes a very light pressure on the system. The absorbent pads are typically made from fluffed purified wood pulp. A facing material 46, typically a nonwoven fabric, is also mated to the assembly under roll 48. This nonwoven material is normally bonded to the backing film along the edges, and may also be bonded to the absorbent pads by thin streaks of hot melt adhesive applied by an applicator, which is not shown. This part of the operation is in the prior art. The thus assembled individual diapers 50 are carried on endless belt 42 to a severing station, not shown. They are maintained under sufficient tension until severed to prevent puckering of the structure in the area in which the elastic has been applied.
FIG. 2 illustrates a typical elastic-leg diaper 54 that might be constructed using the present apparatus. Diapers may optionally contain leg cutouts 58 to add to the comfort of the wearer. The diaper 54 of FIG. 2 is shown maintained under tension, as it would be during the assembly process. FIG. 3 shows the a diaper 56 after it has been severed from the assembly line, much as it would be when received by the user.
Reference is now made to FIGS. 4 through 8 to illustrate in detail the working mechanism of the elastic application unit. The movable clamp 10 is positioned by cam follower 16 riding on cam 14. The cam follower is rotatably mounted on actuating lever 60, which is fixed at its proximal end to pivot rod 64. This rod passes through the body of the rotor 6 where it is held in place by collars 65 in the interior of the rotor. Cam 15 drives cam follower 17 which, in turn, is mounted on actuating lever 62. At its proximal end this actuating lever is fixed to pivot rod 66 which passes through the body of the rotor and is retained in position by collars 67. Pivot rod 66 terminates at its end away from the cams in spring lever 68 which, in turn, is tied to spring 100. This spring severs to hold the cam follower 17 against cam 15. Actuating lever 60 severs to control the position of the movable clamps. Actuating lever 62 severs to control the opening and closing sequence of both clamps and also to operate the shear which severs the individual elastic units from the main body of elastic material. At its distal end the movable clamp positioning lever 60 is pivotally tied to an adjustable end 70 to the inner end of connecting rod 18. The outer end of this connecting rod is pivotally connected by a second adjustable end 74 to the positioning arm 78 of the movable clamp. This positioning arm is attached to pivot rod 80 which also passes through rotor body 6 to operate a similar positioning arm 82 on the other side of the unit.
The clamp/shear activation lever 62 is similarly pivotally connected as its distal end to an adjustable connecting rod end 72, located at the inner end of connecting rod 20. At its outer end, connecting rod 20 bears another adjustable end 76 which is pivotally connected to crank 84. Crank 84 is tied to the clamp/shear activating shaft 86, journaled in bearings 87, 134, which are, in turn, fixed to the frame by cap screws 88, 136.
The clamp/shear activating shaft 86 bears a second short crank 92. Crank 92 is pivotally connected to actuating rod 89 by adjustable end 90. This actuating rod also passes through the body of rotor 6 in order to operate an essentially identical mechanism on the other side of the rotor.
The rotor itself is coupled to drive shaft 7, contained in pillow block bearings 9, 11, which, in turn, are mounted to frame 4 of the elastic applicator. The shaft terminates in sprocket 94 driven through chain 96 by a drive unit, not shown.
Still referring to FIGS. 4, 5, and 7, spring 102 is connected to arm 82 in order to provide a biasing force that holds can follower 17 against cam 15. This spring also serves to hold the movable clamp 10 in the approximate position shown in FIG. 5. The normal position for this clamp would be slightly to the right of that shown in the illustration, where it would abut against the frame of rotor 6.
Movable clamp 10 will now be described in detail. It consists of a body block 112 held by cap screws 114 to the bell crank-form positioning arm 78. The clamp further comprises an anvil or fixed jaw 116 which is rigidly mounted to the body block. It additionally comprises a movable jaw 118 held by spring 120 in a position normally pressing against the anvil. Jaw 118 is attached to a short shaft 122 which passes rotatably through the body block. The other end of this shaft bears jaw actuating arm 124 which contains tang 126 (FIG. 7). This clamp is operated by two cams 128, 130 carried on clamp/shear actuating shaft 86. Cam 128 serves to open clamp 10 by bearing against tang 126 in order to release the elastic 26 at the appropriate time after it is bonded to the article. Cam 130 serves to operate clamp 10 when it is in the position shown in FIG. 7 so that incoming elastic tape may be grasped by this clamp.
Operation of the fixed clamp and elastic shearing mechanism can best be understood by referring to FIGS. 9 through 15. This clamp has a body block 134 which is attached to the rotor body 6 by cap screws 136. The clamp consists of an anvil or fixed jaw 138 along with a movable jaw 140. A third member of this unit is shear 142 which operates against the side of anvil 138 to sever individual elastic units from the main body of elastic. The shear 142 is carried on a short shaft 143 which passes rotatably through the anvil, movable jaw, and body block and is retained at its opposite end by linkage block 150. A light spring 156 serves to maintain the proper positioning of these units. The hairpin spring 144 works between movable jaw 140 and the shear 142 to maintain them normally in the relative positions shown in FIG 11. Shaft 143 passes through jaw 140 so that there is a relatively snug, yet low friction relationship. Movable jaw 140 thus pivots around shaft 143. The movable jaw 140 bears an aperture 146. Pin 148, fixed in the side of the shear element 142, extends into aperture 146 and serves as a stop against the normal action of spring 144 (FIG. 11). The shear element is moved by rotation of shaft 86 working through linkage block 152. This is tied to linkage block 150 by a pair of links 154. As shaft 86 is rotated clockwise, as seen in FIGS. 11, 13, and 15, or counterclockwise as seen in FIGS. 10, 12 and 14, clamp 140 will first close to grasp the elastic tape 126. The movement of clamp jaw 140 is actually effected indirectly through rotation of shear blade 142 by virtue of the fact that the two are flexibly connected by spring 144. As shaft 143 is rotated, movable clamp jaw 140 first drops from the positions shown in FIGS. 10 and 11 against the elastic 23 to hold it against the anvil 138, as shown in FIGS. 12 and 13. With continued rotation of shaft 143, the shear element 142 moves to the position shown in FIGS. 14 and 15 in order to sever the elastic ribbon. Overtravel of the shear element is, in part, limited by pin 148 contacting the opposite side of aperture 146.
The overall operation of the machine can now be better understood by reference to FIG. 16 with further reference to all of the preceeding figures.
The applicator represented in FIGS. 1 and 16 has six individual elastic application modules. It is convenient for one surface of each module to describe an arc equivalent to the overall length of one finished article, in this case, a diaper. In FIG. 16 a single module is illustrated on the right-hand side of the drawing between the locations a and b. These points represent the ends of a single diaper. Points c and d indicate the length of the elastic unit applied to the diaper.
The operation begins with the arrival of elastic 23, which is grasped between clamps 12-2 and 10-1 at location A. Individual modules are designated by the hyphenated number following the numbers which generally indicate the fixed clamps 10 and movable clamps 12. At location A, movable clamp 12-2 of the second module is positioned adjacent to fixed clamp 10-1 of the first module. Leading clamp 12-1 of the first module has already grasped the elastic at this time.
By the time the rotor has moved to position B, both clamps have closed to hold the elastic and the severing knife has operated between them to create an individual elastic unit 26-1. The leading end of the first elastic unit is held in clamp 12-1, while the trailing end is in clamp 10-1. Clamp 12-2 holds the leading end of the following elastic unit. By the time the rotor has advanced to position C the movable clamp, here shown as 12-1, has returned, about halfway, to its normal position. When rotor 6 has advanced to D, the movable clamp has completed its travel and is back at its resting position. In the illustration given, the movable clamp is the leading clamp of the pair. It will be obvious to one skilled in the art that the elastic applicator would be equally functional if this relationship was reversed.
At location E, the glue applicator 28 applies a film of hot melt adhesive to the surface of the elastic units 26. When the rotor has reached point F, slightly more than 180 degrees of rotation from the point at which the tapes were initially grasped, the incoming diaper backing material 30 is pressed by roll 35 against the adhesive coated tapes. By the time the rotor has traveled an additional 10 degrees or so, the leading end of the elastic will be bonded to the plastic and the movable clamp will open to release it. As the rotor continues to point H, the entire elastic unit will have been bonded to the backing and the trailing clamp will open to totally release the elastic unit from the applicator module. Shortly after this point, the movable clamp will begin its travel toward the fixed clamp of the preceding unit, as indicated at I. The two clamps will be in adjacent position by the time the rotor has again reached point A, at which time both clamps will be open in order to receive the incoming elastic and repeat the cycle.
It is evident that the rotor must be traveling in the same direction as the plastic film or other component of the article at the time the elastic unit is bonded to it. It is also desirable that they be traveling at essentially the same peripheral speed. Under some circumstances, a minor differential in speed would be permissible if it was desired to further increase or decrease the elongation of the elastic units but this would not normally be the case. Note that at location G, it is cam 128 on shaft 86 that opens the jaws of the movable clamp to release the leading end of the elastic. At locations A and B it is can 130 on shaft 86 which serves to open and close the jaws of the movable clamp.
EXAMPLE
A six-module applicator was constructed as shown in the drawings, having a diameter of 84 cm. This was used to apply elastic to both leg openings of a medium-sized disposable baby diaper having overal dimensions 44 cm long and 32 cm wide. The backing film was a pigmented, textured polyethylene film 0.025 mm thick. The elastic was made of natural rubber and was 6.2 mm wide and 0.22 mm thick, with an extensibility in excess of 450 percent. This was bonded to the plastic backing film using an elastomeric hot melt adhesive based on a modified SBR rubber with appropriate tackifiers (Findley 995-336 made by Findley Adhesive Company, Elm Grove, Wisc.). The line speed was about 30.5 m/min, equivalent to the production of about 70 diapers per minute. The tensioned elastic units as applied were 25.5 cm in length, leaving about 9.3 cm at the end of each diaper without elastic. As bonded to the backing film, the elastic had about 180 percent stretch so that the applied unit represented about 14.2 cm of relaxed elastic. The nonfunctional material held by the clamps did not amount to more than a few millimeters at each end.
The backing film with elastic attached was combined with an hourglass-shaped fluffed wood pulp pad weighing about 35 gm. This was overlaid by nonwoven fabric weighing 20.5 g/m 2 and bonded to the assembly with a hotmelt adhesive. Before the individual diaper units were severed and folded, side cutouts were made as shown in FIG. 2.
Having thus described the best mode of construction and operation known, it will be apparent to one skilled in the art that many variations could be made in the apparatus and in the method of its operation without departing from the spirit of the invention. For example, it would be equally reasonable to apply the adhesive to the selected areas of the backing film. The relative positions of the fixed and movable clamps could be reversed without changing the method of operation. In the example shown, the device is applying parallel strips of elastic along opposite edges of a disposable diaper. The method and apparatus could be used to apply elastic to other articles of manufacture, such as disposable panties. Other variations will be readily apparent to those skilled in the art.
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The invention is an improved applicator for placing elastic strips on articles such as garments. A continuous of tensioned elastic is gripped sequentially by two clamping means. The elastic unit thus created is severed from the main body of elastic material. One or both clamping means may be movable to adjust the length of the elastic unit and control the position where it is applied to the article. Preferably the elastic is adhesively bonded but it may also be stitched to the article. As soon as bonding is achieved, the clamps are opened in sequence and return to a starting position to repeat the cycle.
The examples disclose a six-module elastic applicator designed to apply elastic to discrete areas adjacent to the leg openings of disposable diapers. This applicator enables more precise placement of the elastic and virtually eliminates waste.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application Serial No. 60/282,240, filed Apr. 6, 2001.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
This invention relates generally to a mattress system, and, more particularly, to a mattress system that combines the benefits of a traditional coil mattress with the additional comfort of an air mattress for use in a sofa sleeper.
It is well known that the mattresses provided within a sofa sleeper can be uncomfortable to those sleeping thereon. This uncomfortability is, in part, a result of the space constraints existing within a sofa sleeper. In other words, the available space within a sofa sleeper for the mattress when the mattress is in a stowed condition necessitates a mattress that is relatively thin. A typical sofa sleeper mattress is used that has an inner spring coil construction. Typically, these mattresses are approximately four inches thick. When a mattress is used that is of this thickness, the person sleeping on the mattress can often feel the support structure for the mattress, such as the steel frame for the sofa sleeper. It would, therefore, be desirable to manufacture a mattress for a sofa sleeper that increased the comfort of the individual sleeping thereon. However, because it is used within a sofa sleeper, the mattress must fit within a typically dimensioned sofa sleeper unit.
Traditional sofa sleepers are designed with a folding frame mechanism that operates to stow the mattress when the unit is used as a sofa, and that is used to deploy and support the mattress when the unit is used as a sleeping surface. When the user of the bed wishes to stow the mattress, the foot portion of the bed is folded upwardly over the mattress. In this position the foot portion of the mattress is folded over the middle portion of the mattress. The end of the mattress assembly is then lifted upwardly, so that the folded-over portion of the foot as well as the middle part of the mattress is lifted. In the lifted position, the mattress assembly is moved towards the back of the sofa sleeper. The back of the mattress assembly is received within the back of the sofa frame, and the foot portion and middle portion of the mattress form the support surface for the cushions of the sofa.
In a sofa sleeper having an air mattress, it is important to properly deflate the air bladder prior to stowing the mattress within the sofa sleeper. Failure to properly deflate the air bladder will cause problems in stowage, such as a failure to completely stow the mattress assembly. In addition, the improper deflation of the air bladder can place additional and unwanted stress upon the support frame.
It is therefore an object of the present invention to provide a sofa sleeper of increased comfort through the use of a combination mattress assembly that can be easily and efficiently stored when not in use.
BRIEF SUMMARY OF THE INVENTION
This invention is directed to a mattress assembly for use in a sofa sleeper. The mattress assembly has a first mattress that has an inner-spring construction. Disposed above the first mattress is a second mattress that has an air bladder construction. The air bladder of the second mattress has a valve, which is located adjacent the head end of the mattress. The valve is adapted to selectively allow air into and out of the air bladder. The mattress assembly thus provides the combination of an innerspring mattress with an air mattress. The location of the valve allows the air mattress portion to be deflated properly and allows convenient access to the valve for inflation or air pressure adjustment purposes.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
These and other objectives and advantages of the present invention will be more readily apparent from the following detailed description of the drawings of the preferred embodiment of the invention that are herein incorporated by reference and in which:
FIG. 1 is a perspective view of a sofa sleeper according to the present invention, with the mattress in the deployed position;
FIG. 2 is a top plan view of the sofa sleeper of FIG. 1;
FIG. 3 is an exploded view of the mattress assembly of the sofa sleeper of FIG. 1;
FIG. 4 is an enlarged view of the encircled region 4 of FIG. 3, showing the valve in the open position;
FIG. 5 is a view similar to FIG. 4, showing the valve in the closed position; and
FIG. 6 is a view similar to FIGS. 4 and 5, showing an inflating pump in place over the valve.
DETAILED DESCRIPTION OF THE INVENTION
With initial reference to FIG. 1, a sofa sleeper according the principles of the present invention is designated generally with the reference numeral 10 . Throughout this specification, the term sofa sleeper is also intended to encompass love seats and other smaller units, such as snugglers. Sofa sleeper 10 is constructed with a sofa frame 12 , which includes a pair of arms 14 and a back 16 . FIG. 1 illustrates the sofa sleeper 10 in the deployed position, useful as a sleeping surface. As best seen in FIGS. 1 and 3, sofa sleeper 10 has a mattress frame mechanism 18 coupled thereto. Frame 18 is any one of a number of existing frames available and known to those of skill in the art. Frame 18 is attached to the sofa frame 12 and operates to move a mattress assembly 20 from the deployed position shown in FIG. 1 to the stored position when sofa sleeper 10 is used a sofa.
As best seen in FIG. 3, the mattress assembly 20 rests upon a support surface 22 provided as part of frame 18 . As an example, support surface 22 can be provided by a number of springs attached to frame 18 and to a resilient fabric material, as is known to those of skill in the art. Mattress assembly 20 includes a lower mattress 24 that is comparable to the mattresses used within sofa sleepers in the past. As such, mattress 24 is typically about four inches in thickness. To provide support, a number of coil springs 26 are used. This type of construction is referred to as an innerspring mattress. As stated above, when mattress 24 is used alone, the mattress is readily stowed within sofa sleeper 10 , but does not provide the desired level of comfort. To increase the comfort of the mattress assembly, additional components are incorporated.
With continued reference to FIG. 3, the mattress assembly 20 includes an inner panel 28 . The inner panel 28 serves as a divider between the lower mattress 24 and an air bladder 30 . A cover border 32 is attached on its lower edge 34 to the inner panel 28 and the lower mattress 24 . Cover border 32 has a zipper attached on its upper edge 38 that is used to removably couple a top panel cover 40 to the border 32 . As viewed in FIG. 2, the zipper preferably terminates in an upper corner of the mattress assembly, so that an upper corner of the bladder 30 can easily be exposed. As can be understood, the inner panel 28 , cover border 32 and top panel cover 40 form a pocket to receive the bladder 30 .
Air bladder 30 is thus received within the pocket formed by panel 28 , cover border 32 and top panel cover 40 . The zipper 36 is moved to a closed position when the bladder is completely inflated, but can be opened either partially or fully, as necessary, as is more fully described below. Air bladder 30 is preferably made from a durable, air impermeable material, such as vinyl. The vinyl side panels 42 and bottom panels 44 are typically exposed. A top surface 46 is coupled to the top of air bladder 30 and is preferably made from a fabric or material, such as a cotton surface or other flocked material. The top surface 46 will thus reduce the potential for noise when sleeping thereon, such as may be experienced if the top were made of a smooth vinyl material. Additionally, the air bladder is constructed with a series of horizontally extending indentations 48 , formed in the top surface 46 . Extending below each indentation 48 is a baffle element located within the air bladder. The baffles operate to properly route the air through the bladder 30 , as would be understood by those of skill in the art.
A valve 50 is integrally formed or coupled with the bladder 30 in the upper corner thereof, as viewed in the figures. Turning to FIGS. 4-6, the valve 50 is seen in more detail. Valve 50 as a large mouth 52 that allows air to escape from bladder 30 quickly when the valve is in an open position. A top 54 is hinged to and snaps over mouth 52 to close the valve 50 . The top 54 is thus moveable between the open position shown in FIG. 4 to the closed position shown in FIG. 5 . The top 54 may additionally be provided with a smaller valve assembly, not shown, which can be used to release small amounts of air. This smaller valve assembly thus provides some adjustability to the firmness of the bladder 30 . As shown in FIG. 5, the top 54 may also have a removable cap 56 that prevents the smaller valve assembly from inadvertent deflation of the bladder. The top 54 is also formed to accommodate an inflating pump 58 as shown in FIG. 6 . Preferably, pump 58 and top 54 are made to mate with one another when the cap 56 is removed, such that when pump 58 is placed on top 54 and is engaged, the pump will activate to fill bladder 30 . Pump 56 is illustrated as having a power cord 60 that supplies power to the pump. Other power supplies could also be used, such as batteries.
To place the sofa sleeper 10 in a position for sleeping, the cushions of the sofa are removed and the frame 18 is pulled from the sofa cavity and unfolded into the position shown in FIG. 3 . In this position, the bladder 30 is still in the deflated condition. The zipper 36 is then used to expose valve 50 , as shown in FIGS. 1 and 2. The cap 56 is removed from the top 54 and the pump 58 is engaged with the top, as shown in FIG. 6 . The engagement of the pump with the top causes the pump to fill the bladder 30 with air. When the bladder 30 is filled with an amount of air suitable to the comfort needs of the user, the pump 58 is disengaged from top 54 and the cap 56 is replaced on top 54 . The top panel cover is then re-zipped to hide the valve 50 . The sofa sleeper in this position is ready for sleeping. The additional support provided by the bladder 30 within the mattress assembly 20 increases the overall comfort of those sleeping upon the sofa sleeper. Moreover, the top surface of the bladder 30 reduces any noise associated with the material of the bladder.
When the mattress assembly 20 is to be stowed within sofa sleeper 10 , the zipper is used to expose valve 50 . The top 54 of the valve is then opened, allowing air to escape from the bladder 30 through mouth 52 . The large opening allows air to rapidly escape from the bladder. The removal of air is furthered by the positioning of the valve and the operation of the frame 18 . More specifically, after valve 50 is opened, the foot end of frame 18 is folded upwardly and inwardly, as with a traditional sofa sleeper mechanism. The foot end is folded over, so that the foot end portion of the mattress assembly rests on the middle portion of the mattress assembly. This folding operation results in air being “squeezed out” of the bladder 30 , pushing the air towards valve 50 and out mouth 52 . The frame 18 is then moved into the stowed position, which pushes any remaining air out of the bladder 30 . The positioning of valve 50 therefore reduces the likelihood that any significant amount of air will remain within bladder 30 when the mattress assembly 20 is moved to a stowed position. Therefore, the likelihood that the mattress assembly will not stow properly, or that any damage will be done to mattress frame 18 is also reduced. If the valve were placed in an area other than the head end of the bed, such as at the foot of the bed, the likelihood of improper deflation increases.
Should the bladder ever need replacement or repair, the zipper 36 allows full and easy access to the bladder without damaging the mattress assembly in any way. Zipper 36 also provides easy access to the valve 50 for any necessary operations, such as opening and closing the valve and making pressure adjustments to the air bladder 50 .
The present invention has been described in relation to particular embodiments, which are intended in all respects to be illustrative rather than restrictive. Alternative embodiments will become apparent to those skilled in the art to which the present invention pertains without departing from its scope.
From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects set forth above, together with other advantages which are obvious and inherent to the system and method. 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 and with the scope of the claims.
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This invention is directed to a mattress assembly for use in a sofa sleeper. The mattress assembly has a first mattress that has an inner-spring construction. Disposed above the first mattress is a second mattress that has an air bladder construction. The air bladder of the second mattress has a valve, which is located adjacent the head end of the mattress. The valve is adapted to selectively allow air into and out of the air bladder. The mattress assembly thus provides the combination of an innerspring mattress with an air mattress. The location of the valve allows the air mattress portion to be deflated properly and allows convenient access to the valve for inflation or air pressure adjustment purposes.
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BACKGROUND OF THE INVENTION
The invention relates to a device for making seams on three-dimensional objects made of materials such as textile woven materials, leather, synthetics or similar materials. Such devices are used for the production of clothing, upholstery for seating furniture and automobiles, and for the production of shoes.
Usually, three-dimensional objects such as envelopes made of fabric are manufactured in such a way that pre-made two-dimensional cuttings are sewn lying flat on top of each other with a sewing machine. The two cuttings are sewn together at an exactly specified distance from the cutting edges. Beforehand, the cuttings have been provided with markings which have to match during sewing, and it is also necessary to displace the cuttings relative to each other during sewing. Joining of the cuttings by means of a sewing machine is very time-consuming and requires a high degree of routine of the operator who has to guide the cuttings and operate the sewing machine. Because of the relatively slow manual control, the performance possibilities of the sewing machine are not fully utilized. The feeding of the materials is made by the sewing machine intermittently between the penetration movements of the needle. From DE 33 38 405 A1, a device for producing three-dimensional articles provided with seams is known wherein a sewing machine is attached to a manipulator in the form of a robot arm. This sewing machine is moved by the manipulator in such a manner that said sewing machine is guided along the intended seam line of the two cuttings to be sewn. An under-thread bobbin grips underneath the cuttings to be sewn and a presser presses against the top cutting. The lower cutting is supported by a brush bed through which the under-thread bobbin moves.
A similar sewing device is known from EP 0 344 400 A1. Here, too, a sewing machine is secured to the manipulator arm of a robot, the details of which sewing machine, however, are not described.
The known devices on which a sewing machine is moved by a manipulator in a three-dimensional system involve the difficulty of obtaining a neat and distortion-free seam and still carrying out the sewing action at high working speed.
SUMMARY OF THE INVENTION
It is the object of the invention to provide a vice for making seams on three-dimensional objects, which permits the production of perfect and distortion-free seams.
This object is solved, according to the invention; with the features indicated in claim 1.
In the sewing device according to the invention, the sewing machine comprises a sewing head the movement of which is controlled such that during the penetrations of the needle into the material, it is at a standstill relative to the holding device carrying the workpiece. These standstill actions can be produced in different ways. One possibility is to move the manipulator arm in coordination with the needle movements of the sewing machine along the seam line such that said manipulator arm is at a standstill during the penetration and withdrawal movements of the needle and only moves the sewing machine when the needle is pulled out of the material. Another possibility envisages that the sewing head is movably guided in a linear direction on the manipulator arm such that at the point when the needle is in the material, said sewing head is moved backward along the intended seam line relative to the manipulator arm at about the same speed and afterwards, when the needle is pulled out of the material, the amount of lost movement is caught up again. The manipulator arm can then be moved at constant speed such that the tool center point of the manipulator moves at constant speed along the seam line, the sewing machine, however, alternately falling short of the tool center point and catching up the lost movement again. To this end, a guide is secured to the manipulator arm which guide is always aligned parallel to the intended seam line and along which the entire sewing machine is linearly guided. Finally, it is also possible to move the holding device for the fabric by means of the manipulator arm while the sewing machine is stationary, the entire sewing machine or only the parts of its sewing head being linearly moved to carry out the follower movement.
It is also within the scope of the invention to mount the sewing machine firmly on the manipulator arm and move the sewing head or the individual components thereof along linear ways of displacement such that the sewing head is at a standstill relative to the workpiece during stitching movements of the needle. In this case, too, the manipulator arm can be moved at constant speed, while the back and forth compensating movements are carried out exclusively by the sewing head relative to the sewing machine.
Continuous movement of the manipulator arm has the advantage that the masses which have to be moved intermittently dependent on the stitch movements of the needle can be kept relatively small and that it is not necessary to mutually coordinate the movements of the manipulator arm and the stitching movements of the needle.
In the sewing machine according to the invention, the feeding stroke for sewing the seam is made exclusively by the manipulator arm while the workpiece itself is at a standstill. Here, the holding device carrying the workpiece does not necessarily have to be absolutely fixed, but can be fitted so that it can be turned, for example. It is important that the sewing machine itself has no feeding device and that the material is not moved further between two stitches.
For the purpose of permitting a relative movement of the sewing head with respect to the workpiece between two stitches, the needle plate and the presser are moved apart when the needle is pulled out of the material. In this state, the sewing head (or the entire sewing machine) can be moved by one stitch length relative to the workpiece. After that, the material is again clamped between needle plate and presser in order to provide for an exact position of the workpiece for the next needle stitch and an exact mutual alignment of the cuttings to be sewn.
Hereinafter, embodiments of the invention are explained in detail with reference to the drawings.
In the figures:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a holding device with cuttings to be sewn together secured on it,
FIG. 2 an illustration of the holding device together with the manipulator and the sewing machine mounted therein,
FIG. 3 a section along line III--III of FIG. 2,
FIG. 4 a front view of the sewing machine,
FIG. 5 a diagram of the time coordination of the movements of the sewing head with the stitch movements of the needle, and
FIG. 6 a side view of another embodiment in which the sewing head is linearly movable relative to the sewing machine.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a holding device 10 carrying individual cuttings which are confronted with each other in order to form a three-dimensional hollow object from two-dimensional material. The workpiece to be manufactured the cuttings of which are secured on the holding device 10 consists of the sleeve for an armrest of a motor vehicle.
The holding device 10 comprises a basic body 11 about which a cutting 12 in the form of a bandshaped strip is placed. This cutting 12 is secured on the basic body 11 by holding plates 13 which are pressed against the cutting from the outside. The cutting 12 encompasses the basic body 11. The side of the ring formed by the cutting 12 is to be closed by a cutting 14 in the form of a side part to be sewn on. The cutting 14 is placed against the side surface of the basic body 11 and held there by a holding plate 15 which is pressed against the basic body. Holding of the holding plates 13 and 15 on the basic body 11 can be effected, for example, by magnets or by suction.
The cuttings 12 and 14 are of such a size that they overlap at the circumferential edges where they form edge strips 16 (see also FIG. 3). At the root of these edge strips 16, the seam 17 is produced.
FIG. 2 shows the holding device 10 which is fitted on a holder (not shown) in a stationary manner, and a sewing machine 18 mounted on a manipulator arm 19. The manipulator arm 19 is a part of the manipulator 20 which, in this case, is an industrial robot with a plurality of movement axes, for example with six or eight movement axes. The manipulator 20 is numerically controlled such that the tool center point, i.e. the effective point of a tool firmly fitted on the manipulator arm 19, can be moved along a predetermined movement path. Programming of the manipulator 20 can be made such that the manipulator arm 19 with the tool secured thereto is manually guided along the intended processing line in a teaching phase. The path values recorded in this way are stored, and subsequently, the manipulator 20 is controlled such that the manipulator arm 19 performs the same movements in a controlled manner which were carried out in the teaching phase. The tool secured on the manipulator arm consists of the sewing machine 18 in this case.
On the manipulator arm 19, a linear guide 21 is secured along which a carriage 22 which carries the sewing machine 18 can be moved. The guide 21 is aligned transversely to the needle of the sewing machine 18 and it extends parallel to the seam line 17 to be produced. The carriage 22 is driven by a drive (not illustrated). This drive may consist of the drive motor 23 of the sewing machine, in which case the carriage movement may be produced by a cam disk moved by this drive motor 23.
According to FIG. 3, the drive motor 23 of the sewing machine 18 drives a drive shaft 25 via a belt drive 24, said drive shaft driving the components of the sewing machine in the known manner. The sewing machine comprises a sewing head 26 which is arranged in a fixed association with respect to the sewing machine housing 18a. Belonging to the sewing head 26 are the needle lever 27 which is fitted to a back and forth moving turned shaft 28 and carries the curved needle 29, a needle plate 30 which forms an abutment for the double-layered edge strip 16 and comprises a cutout for penetration of the needle 29, a presser 31 arranged opposite the needle plate 30 and a shuttle hook 32 which is arranged behind the needle plate 30 and contains the under-thread supply. The needle 29 is curved about the axis of the shaft 28.
During the penetration of the needle 29, the edge strip 16 is clamped firmly between the needle plate 30 and the presser 31. When the needle is pulled out of the edge strip 16, the needle plate 30 and the presser 31 move apart in order to release the edge strip. The opening and closing movement of the presser 31 is controlled by the needle lever 27 which, when the needle is pulled out of the material, engages a stop 33 of the presser 31 so that the presser is lifted from the edge strip 16 against the action of the spring 34 which pulls said presser in the direction of the needle plate 30.
The needle plate 30 is also removed from the edge strip when the needle is withdrawn. This is effected by the fact that an arm 35 carrying the needle plate 30 is moved by a cam control 36 synchronized with the needle lever movement.
On the needle plate 30 or on the presser 31, a sensor 37 is provided which detects the presence of the edge strip 16 and makes the sewing machine inoperative when an edge strip has not been detected. This sensor can be a light-cell barrier, for example, in which the light emitter is fitted on the needle plate 30 and the receiver on the presser 31.
According to FIG. 4, the thread 38 coming from a yarn bobbin (not illustrated) passes over a roller 39 driven by a stepping motor and further over a diverting pin 40 to the thread take-up 41 movable up and down in the rhythm of the needle movement. From there, the thread 38 passes to a thread brake 42 provided on the needle lever 27 and further to the needle hole arranged close to the tip of the needle 29. The stepping motor driving the roller 39 is set into function in every cycle after completion of the upward movement of the thread take-up 41 in order to provide for the amount of thread which corresponds to the predetermined stitch length. A pressing roller presses the thread firmly against the roller 39 driven by the stepping motor such that the thread is moved by the roller 39 without slippage. When the roller 39 stops moving, it is held by the stepping motor so that no pulling of the thread from the thread supply by the pulling forces behind the roller 39 is possible.
It is assumed that the carriage 22 is in its forward end position in the movement direction of the manipulator arm 19. In this position, the location of penetration of the needle 29 into the material represents the tool center point of the manipulator. The manipulator arm 19 is moved by the manipulator 20 such that the tool center point moves along the intended seam line.
The drive motor 23 of the sewing machine 18 is controlled in dependence on the movement of the manipulator arm such that the stitch length (the way from penetration point to penetration point) remains constant, independently of the feeding speed. To this end, the speed component derived from the path encoders of the manipulator in seam direction is compared with the speed of the sewing machine motor. Before the tip of the needle 29 penetrates the edge strip 16, the needle plate 30 and the presser 31 are moved towards each other. Simultaneously, the carriage 22 is moved along the guide 21 opposite the feeding movement carried out by the manipulator arm 19 (along the intended seam line), and at a speed which corresponds to the feeding speed. Thereby, the sewing machine 18 stops relative to the holding device 10 or the workpiece during the penetration of the needle 29 into the material, whereas the manipulator arm 19 is continuously moved further. The requirement for this is that the manipulator arm 19 is aligned parallel to the intended seam direction. When the needle 29 has been withdrawn from the material, the carriage 22 is moved along the guide 21 into its front end position again, whereas the manipulator arm 19 continues its continuous feeding movement.
These movement conditions are shown in FIG. 5. Here, in the upper illustration, the course in time of the stitch movements s of the needle 29 is shown, the amplitude increasing the farther the needle tip is pushed forward from its withdrawal position through the needle plate 30. In the lower illustration, the absolute speed v of the sewing machine 18 is shown, v R being the constant feeding speed of the manipulator arm 19. As long as no stitch movements are performed, the sewing machine 18 is in its front end position with respect to the manipulator arm 19 and it moves at the feeding speed v R . When a stitch movement is made, the sewing machine 18 moves along the guide 21 opposite to the direction of the feeding speed so that the absolute speed becomes zero. After withdrawal of the needle tip from the material, the sewing machine 18 is moved along the guide 21 into the front end position again, this feeding movement overlaying with the feeding speed v R of the manipulator arm 19. In the front end position, the carriage 22 remains until the next stitch is carried out. The drive of the carriage 22 with respect to the guide 21 is effected by the sewing machine drive and in synchronization with the needle movements.
In the embodiment of FIG. 6, the sewing machine 48 is firmly and rigidly connected with the manipulator arm (not illustrated), and the components of the sewing head 26 are displaceable opposite to the direction of the intended sewing direction indicated by the arrow 49. The components of the sewing machine 48, insofar as they correspond to the components of the above-described sewing machine 18, are provided with the same reference numbers. The following description is restricted to the differences of the sewing machine 48 compared with the sewing machine 18.
On the sewing machine 48, the needle lever 27 is not rigidly connected with the shaft 28, but is displaceable along this shaft. In the same way, the arm carrying the presser 31 is secured to the shaft 28 for rotation therewith, but is displaceable along this shaft.
Displacement of the needle lever 27 and the presser 31 is effected by a fork 50 controlled by a cam disk, said fork engaging in an annular groove in a sleeve 51 located on the shaft 28 and being controlled synchronously with the needle drive. In a similar manner, the needle plate 30 and the shuttle hook 32 are displaceable in the direction of the arrow 49 and in the opposite direction.
The seam 17 is sewn on the workpiece such that the double-layered edge strip 16 outwardly protrudes from the cuttings. Subsequent to the completion of the seam, the workpiece is turned, the surfaces lying on the outside during production coming to lie on the inside.
Although a preferred embodiment of the invention has been specifically illustrated and described herein, it is to be understood that minor variations may be made in the apparatus without departing from the spirit and scope of the invention, as defined the appended claims.
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For making seams on three-dimensional objects, a manipulator (20) is used at the manipulator arm (19) of which a sewing machine (18) is secured. The cuttings (12,14) to be sewn are fixed to a holding device (10), and the sewing machine (18) sews the protruding edge strips (16) which confront each other. The sewing machine (18) can be guided by the manipulator arm (19) along the intended seam line at constant speed. While the needle penetrates the material, the sewing machine being guided on a guide (21) by means of a carriage (22) is driven in a direction opposite to the feeding direction of the manipulator so that the sewing machine is at a temporary standstill with respect to the holding device (10). After completion of the stitch, the carriage (22) is advanced on the guide (21) in feeding direction so that the sewing machine catches up with the lag. With each stitch, the edge strip (16) is clamped between a needle plate and a presser of the sewing machine.
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BACKGROUND OF THE INVENTION
The invention herein pertains to new and useful means for facilitating the filling and handling of conventional plastic trash bags and the like.
The conventional plastic trash bag, normally formed of extremely thin and flexible plastic, for example low density polyethylene, has come into common usage for a great variety of purposes both around the home and elsewhere. The widespread acceptance and use of such bags evidences their basic practicality, notwithstanding that the extremely flexible or flacid nature of such bags makes them difficult to fill and handle, and easily torn when sharp edged materials are packed therein.
One of the more common uses of the larger sizes of such bags, and an area wherein the present invention is particularly, although not exclusively, concerned, is in the collecting of lawn and garden debris which ranges from heavy compacted grass clippings to sharp edged twigs, small branches, and the like. The use of such bags in this environment is less than completely convenient in view of the flexible nature of the bag and the necessity for retaining the bag, and particularly the mouth thereof, open in order that the debris might be either dropped therein or in some manner swept therein. One proposed solution to this problem will be noted in U.S. Pat. No. 4,193,157 issued to Helen F. Large, wherein a plastic hoop is inserted into the open mouth of the bag and a ramp provided in outwardly extending relation to the hoop for the inward guiding of swept debris. Similar bag mouth engaging devices will also be noted in U.S. Pat. No. 112,727 issued to W. F. Lum, and U.S. Pat. No. 1,167,782 issued to J. W. Richards.
Other proposals for stabilizing flexible bags will be noted in the following U.S. Pat. Nos.:
2,384,709 Thoren;
3,915,329 Zaks;
3,917,107 Bottas et al;
3,945,314 Hennells.
Zaks proposes a filling device for plastic trash bags which is frusto-conical and received, as a liner, within a plastic bag which may in turn be supported by the liner. Bottas et al and Hennells are concerned with refuse compactors and provide inner supports for bags which are in turn received within receptacles. This is also generally shown in Thoren wherein the inner support is in the nature of a collar.
While not specifically noted in the above patents, it is also a common expedient to provide a plastic bag within a conventional trash can with the upper portion of the bag draped over the side of the can, thus providing some degree of stability to the flexible bag during the loading thereof. However, a major problem encountered with such an arrangement is the tendency for introduced debris, particularly when involving prickly branches, twigs and the like, to tear or shred the bag. This occurs both during the introduction of the material and as the loaded bag is being removed. There is also the problem of the bag slipping into the supporting can or receptacle during the loading.
SUMMARY OF THE INVENTION
It is a primary intention of the present invention to provide a filling aid or device which, when used in conjunction with a conventional trash can, provides an effective means for positioning and stabilizing a flexible trash bag, protecting the bag against destructive tears and the like, stabilizing the assembled apparatus in a position whereby debris can be directly swept or raked thereinto, and providing a guidance means which facilitates a direct introduction of debris into the bag and at the same time provides a convenient assist for firmly packing the debris into the bag.
Basically, the filling aid includes an elongated tubular sleeve open at the opposite upper and lower ends and longitudinally slit along the full length thereof. The upper end of the sleeve has a full peripheral outwardly and downwardly turned edge flange.
A scoop, either integrally formed with or intimately attachable to the sleeve, extends longitudinally outward from the upper end of the sleeve immediately inward of the outwardly turned edge flange, the scoop providing in effect a smooth continuation of the inner wall of the sleeve. The inner edge of the scoop, the edge engaged with the upper end of the sleeve, is of an arcuate configuration, extending about approximately one half the circumference of the open end of the sleeve. The outer edge of the scoop is straight and of a length greater than the normal diameter of the sleeve. The opposed ends of this outer edge curl slightly inwardly into the opposed sides of the scoop which extend to the arcuate inner edge of the scoop and define, in conjunction with the body of the scoop, an overall tapered configuration which is substantially semicircular at the top end of the sleeve for a direct flow of debris into the sleeve. The outer edge portion of the scoop, remote from the sleeve, is planar to provide a stabilizing ground engaging portion with a wide entry area into which debris can easily be swept or raked.
It is contemplated that the filling aid be formed of relatively rigid plastic, such as for example a high density polyethylene, which incorporates a degree of inherent resiliency sufficient at least to enable a circumferential adjustment of the sleeve, provided for by the longitudinal slit. Other appropriate material, such as for example sheet metal, might be used if deemed appropriate. Further, should the scoop be formed as an attachable component, for example to facilitate packing and shipping, the sleeve portion of the aid might be formed of plastic and the scoop of sheet metal.
In actual size, the sleeve, normally through an initial circumferential collapsing thereof, is inserted within a plastic trash bag which is in turn received within a conventional rigid trash can. The sleeve extends to a point closely adjacent the bottom of the can so as to protect the bag along substantially the full height thereof. The upper edge of the bag is in turn folded over the upper rim of the can and frictionally locked thereto by the sleeve edge flange. The can is then laid on its side with the planar outer portion of the scoop directly engaging the ground and providing a wide mouth for the sweeping of the debris into the liner protected bag.
After a loading of the debris and a reasonable compacting thereof through the action of the rake, broom or the like, additional debris is loaded onto the scoop and the entire assembly positioned upright. The scooped debris, through the funnel-shaped nature of the scoop, will feed into the can assembly, and act to further compact the material therein, either with or without a little pressure assist from the user.
The entire assembly can be easily carried, through the conventionally provided handles on the can, to the point of disposal. The bag and the liner formed sleeve can then be removed as a unit from the can with the sleeve still affording substantial protection to prevent damage to the bag by the debris. Further, the relatively rigid nature of the sleeve greatly simplifies a removal from the can. Ultimately, the sleeve is slipped from the bag and the bag tied for disposal. In slipping the liner from the bag, it will be appreciated that while there does exist some possibility of sharp twigs or the like poking into the bag and causing minute holes, there is substantially no danger of destructive long tears or rips being formed, as would be the case were the debris forced directly into the plastic bag itself, or were the debris allowed to poke through the bag prior to removal of the bag from the can.
It will be readily appreciated that additional objects and advantages, which will become subsequently apparent, reside in the details of construction and operation of the invention as more fully hereinafter described and claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the entire debris receiving assembly;
FIG. 2 is a perspective view of the filling aid itself;
FIG. 3 is a longitudinal cross-sectional view through the assembly of FIG. 1;
FIG. 4 is an illustration of the assembling of the components;
FIG. 5 is a perspective view of the assembly in position to receive debris; and
FIG. 6 is a top plan view of the filling aid.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now more specifically to the drawings, reference numeral 10 is used to generally designate the filling aid comprising the present invention. The filling aid includes an elongated tubular sleeve 12 having open bottom and top ends 14 and 16 respectively. The sleeve, in order to allow for a circumferential adjustment, is provided with a full length longitudinal slot 18 defined by a pair of parallel longitudinal sleeve edges 20. The circumferential adjustment of the sleeve 12 is effected manually, and made possible by both the tubular configuration of the sleeve and the use of an appropriate relatively rigid plastic, such as high density polyethylene, having an inherent degree of resiliency. As an example of the use of such material, attention is directed to the conventional plastic garbage can. The sleeve is completed by providing the upper edge of the sleeve, about the open end 16 thereof, with a full length outwardly and downwardly turned edge flange 22, the purpose for which shall be explained subsequently.
The filling aid 10 also includes an enlarged debris funneling scoop 24 which, as illustrated, may be integrally formed with the sleeve 12. The scoop 24 includes an arcuate inner edge 26 which conforms to and extends about approximately one half of the circumference of the open outer end 16 of the sleeve 12. This inner edge 26 of the scoop 24 is positioned whereby the scoop surface forms a substantially smooth continuation of the aligned inner surface of the sleeve 12. As will be best noted in the cross-sectional view of FIG. 3, the reversely turned edge flange 22 continues behind the inner edge 26 of the scoop 24.
The outer edge 28 of the scoop is straight and of a length greater than the diameter of the sleeve 12, projecting equally beyond diametrically opposed points on the sleeve whereby a tapered configuration is provided with the scoop defining a generally funneling configuration from the planar outer edge portion to the semi-circular sleeve engaged inner edge portion.
The opposed side edges 30 are straight and extend slightly divergently from diametrically opposed points at the upper reversely turned rim of the sleeve to arcuate outer corners which merge with the transverse straight outer edge 28.
The portions 32 of the scoop 24, immediately adjacent the side edges 30, are planar or flat and project generally in a plane perpendicular to the flat central portion 34 which defines an area tapering from a maximum width along the straight outer edge 28 to a minimal width at the inner edge 26 adjacent the open end 16 of the sleeve 12. The arcuate configuration of the scoop, between the flat central portion 34 and each of the generally perpendicular edge portions 32, can be of a constant tapered curvature, or formed of a series of individual folds, each extending from a point 36, generally at the juncture between the straight outer edge 28 and the arcuate corner, and a series of circumferentially spaced points along the inner edge 26 of the scoop 24. The generally perpendicular orientation of the side edge portions 32 provides for a positive and effective retention of the debris being moved through the scoop.
Other features which will be noted from the drawings include the provision of the adjustment accommodating slit 18 at a point circumferentially about the sleeve 12 away from the scoop. Further, it will be noted that the scoop is angled slightly laterally outward so as to provide for a positive engagement of the straight outer edge 28 thereof with the ground during the use of the filling aid as will be described presently.
While the scoop has been described as being integrally formed with the sleeve, if desired for shipping or storing purposes, or as a matter of convenience, the scoop can be separately formed and even formed of a different material, however, this will necessitate means for effecting a positive interlock of the scoop with the sleeve in an appropriate manner.
As will be appreciated from the drawings, the filling aid 10 is specifically adapted and intended for use in conjunction with a conventional receptacle or can 38 as a means for positioning, stabilizing and filling a conventional flexible trash bag 40.
For purposes of illustration, the outer rigid trash receptacle or can 38 has been illustrated as a conventional 26-gallon garbage can, normally having opposed carrying handles 42. Other sizes and forms of open topped containers or receptacles can also be used, with the filling aid, in each instance, being formed for use in conjunction with the particular receptacle or closely sized similar receptacles. For example, while the illustrated filling aid has been presented as being of a size for specific use with a conventional 26-gallon can, due to the adjustable nature of the filling aid, other similarly sized receptacles can be used, for example a conventional 30-gallon can.
In use, a flexible bag 40 is placed within the can 38 and internally receives the sleeve 12 for a sandwiching of the bag between the sleeve and can. This can be effected in either of two ways. First, the bag can be manually placed within the can with the closed bottom of the bag resting on the closed bottom of the can and with the open end of the bag having the edge portion thereof draped over the can rim. After the bag is so positioned, and manually opened at least to a degree sufficient to accommodate the collapsed sleeve, the sleeve 12 is circumferentially constricted, possibly forming a slight tapering thereof toward the lower end, and introduced into the can supported bag, taking care not to push the bag completely into the can. Once properly positioned, the sleeve is allowed to expand, possibly being manually assisted, so as to bring the bag into snug engagement with the inner wall of the can or receptacle. After an expansion of the sleeve so as to effect the snug engagement of the bag against the can wall, the reversely turned flanged upper edge of the sleeve is forced downwardly over the can rim so as to frictionally clamp the upper edge of the bag therebetween, thus avoiding any tendency for the bag to slip into the can during the filling thereof.
As an alternate manner of assembling the filling aid, bag and can, the sleeve of the filling aid can be introduced directly into the flexible bag, or the bag slid over the sleeve, collapsing the sleeve to the degree necessary to accommodate the bag, with the then assembled sleeve and bag introduced into the can. Again, care is taken to provide a snug sandwiching of the bag between the sleeve and the surrounding can wall, along with a firm frictional clamping of the outer portion of the bag over the can rim. By extending the reversely turned flange on the open upper end of the sleeve along the full length thereof, even throughout the full extent of the scoop immediately outward thereof, a positive retention of the bag is effected peripherally thereabout.
It will be appreciated that the peripheral contractible nature of the sleeve allows for its accommodation in cans of varying diameter, as well as cans which might incorporate a slight degree of taper therein, in which instance, the overlap between the adjoining free edge sections of the sleeve will be greater toward the tapered small end of the can.
Ideally, the sleeve 12 will form a liner for the full height of the bag 40 within the can 38. This is significant in that the greatest damage to the conventional thin plastic bags arises from sharp articles, branches, and the like being pushed into plastic bags and along the length thereof whereby long tears or slits are formed. With the liner forming sleeve of the present invention, the sleeve itself, formed of a heavy gauge plastic or the like, easily resists any destructive tearing or slitting.
While it is preferred that the sleeve extend the full height of the can received bag, in leaving of a small exposed section of the bag below the lower end of the sleeve, such as would occur were the filling aid for a 26-gallon can used in a 30-gallon can, little destructive tearing would occur in that a substantial radial inward compressing and settling of the debris would occur as the debris travels the full height of the sleeve. Further, a little judicious packing of the debris could easily accommodate a slight exposure of the lower portion of the bag. For example, softer materials, such as grass or the like, can be introduced to form a mat at the bottom of the bag, prior to the packing of branches or the like therein.
When laid on the ground, the scoop 24, an integral part of the filling aid, provides, at its outer edge, a wide flat ground engaging mouth into which debris is easily swept or raked. The tapered configuration of the scoop, along with the perpendicular side edge portions, easily and conveniently funnel the debris into the tubular sleeve, and thus into the receptacle mounted bag without significant contact with any portion of the bag, other than the closed end thereof, until such time as the sleeve is removed. The wide flat outer edge of the scoop stabilizes the normally cylindrical receptacle, preventing any tendency for the receptacle to roll or turn as the debris is loaded therein.
After a fairly tight compacting of the debris into the assembly, utilizing the raking or sweeping implement, the scoop itself can be provided with a final load of debris and the assembly swung upward. The funnel shaped scoop will tend to retain the debris thereon and provide a converging path down which the debris moves to further compact the material into the receptacle and sleeve-supported bag. Should it be considered desirable, a minor degree of tamping can assist in compacting the debris within the bag received sleeve. However, no substantial physical force, as for example a stepping into the can, will be required in that the major compacting force will be derived from the material within the enlarged scoop itself moving downward and inward.
The removal of the loaded bag, or the handling of the assembly, can be effected in any of a variety of convenient ways. For example, the filling aid and bag can remain in the can while the entire assembly is conveniently carried, by the can handles, to a point of disposal, after which the filling aid and bag are separated as a unit from the can with the final step involving a sliding of the sleeve from the bag. In this manner, the bag is at no time subjected to a sliding movement of sharp twigs, branches, or the like therealong, such as could cause destructive tears or slits. As an alternative manner of removing the bag, the first step can involve a sliding of the sleeve from the can-received bag, after which the loaded bag is itself slid from the can. This procedure, depending on the nature of the debris, might be slightly more difficult in that the debris confining force of the relatively stiff sleeve will have been removed.
The foregoing is considered illustrative only of the principles of the invention. Further, since modifications and changes may 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. Accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.
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A filling aid selectively positionable within a can-received flexible bag for a stabilization and protection of the bag and a guiding of debris and the like into the bag. The aid includes an elongated tubular split sleeve having open inner and outer ends and being of a resiliently flexible nature for a selective varying of the circumferential size thereof. The outer end of the sleeve includes an outwardly curled flange engageable over a can rim for the clamping of a bag thereto. An outwardly flaring scoop extends longitudinally from the flanged end of the sleeve, tapering from engagement with the periphery of the sleeve about approximately one half the circumference thereof, to a straight outer edge of a length greater than the normal diameter of the sleeve.
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BACKGROUND OF THE INVENTION
[0001] The present invention relates, in general, to ultrasonic systems and, in particular, to methods and circuitry for driving a high-power ultrasonic transducer for use with a varying load.
[0002] Ultrasound technology is utilized in a variety of applications from machining and cleaning of jewelry, performing surgical operations to the processing of fluids, including hydrocarbons. The basic concept of ultrasonic systems involves the conversion of high frequency electric energy into ultrasonic frequency mechanical vibrations using transducer elements. Such systems typically include a driver circuit that generates electrical signals which excite a piezoelectric (or magnetostrictive) transducer assembly. A transmission element such as a probe connects to the transducer assembly and is used to deliver mechanical energy to the target.
[0003] Ultrasonic transducers include industrial and medical resonators. Industrial resonators deliver high energy density in order to substantially affect the materials with which they are in contact. Common uses of industrial resonators include welding of plastics and nonferrous metals, cleaning, abrasive machining of hard materials, cutting, enhancement of chemical reactions (sonochemistry), liquid processing, defoaming, and atomization. Usual frequencies for such operations are between 15 kHz and 40 kHz, although frequencies can range as low as 10 kHz and as high as 100+ kHz. Medical resonators include devices for cutting, disintegrating, cauterizing, scraping, cavitating, dental descaling, etc.
[0004] A transducer assembly for an industrial ultrasonic application may be referred to as an industrial ultrasonic stack, and may include a probe (or a sonotrode, or a horn), a booster, and a transducer (or a converter). The probe contacts the load and delivers power to the load. The probe's shape depends on the shape of the load and the required gain. Probes are typically made of titanium, aluminum, and steel. The booster adjusts the vibrational output from the transducer and transfers the ultrasonic energy to the probe. The booster also generally provides a method for mounting the ultrasonic stack to a support structure. The active elements are usually piezoelectric ceramics although magnetostrictive materials are also used.
[0005] Existing technology for driving ultrasonic probes has been developed for driving a system at one desired frequency and power level for a specific process. This known technology utilizes an electrical system based on a Silicon Controlled Rectifier (SCR). Typically, SCR's require a forced turn off system having a particular capacitor value to control and turn off the SCR which in turn limits the operating frequency of the electrical system. Also, the SCR systems are limited to much lower power levels which do not allow for the effective control of an ultrasonic probe at higher power levels. As used herein, a high power level refers to power levels of at least 500 Watts. For example, the SCR-based ultrasonic generators drive ultrasonic probes which are designed for a specific load such as molten steel. However, an SCR-based ultrasonic generator when used in a process which exposes an attached ultrasonic probe to varying load conditions, such as the processing of liquid hydrocarbons, limits the effectiveness of the probe in different liquids. This limited effectiveness is due to the loading effect different liquids will have on the ultrasonic probe. In addition, even for a given liquid, density and phase change effects can vary the loading on the ultrasonic probe.
[0006] There is therefore a need for a high-power and variable load driving circuit for an ultrasonic generator that does not suffer from the shortcomings of SCR-based ultrasonic generators.
BRIEF SUMMARY OF THE INVENTION
[0007] The present invention provides an ultrasonic generator for driving a dynamic ultrasonic probe system for use with variable loads, at operating frequencies of up to 20 kHz and power levels of up to 60 kW. The system utilizes a Full Bridge Isolated Gate Bipolar Transistor (IGBT) system to drive ultrasonic probes at a resonant frequency at different and adjustable voltage, frequency, and current levels. As an ultrasonic probe experiences different loads the electrical power requirements will change. For example, during various hydrocarbon processing (e.g., desulfurization) techniques, such as those patented by the assignee herein, many different and varying loads are seen by an ultrasonic transducer as different fluids (e.g., such as different types of crude oils, diesel fuels, etc.) are processed. Various patented hydrocarbon processing techniques which are patented by the assignee herein are disclosed in U.S. Pat. Nos. 6,827,844; 6,500,219 and 6,402,939, the disclosures of which are hereby incorporated by reference herein. By using a system such as the Full Bridge IGBT based system, in accordance with the embodiments of the present invention, one can control the required variables such as frequency, voltage and current to effectively manage the performance of the ultrasonic probe for varying loads. The varying loads typically include different compressible and incompressible hydrocarbon fluids.
[0008] In one aspect, the embodiments of the present invention are directed to a high-powered (e.g., >500 W) ultrasonic generator for delivering high-power ultrasonic energy to a varying load. In one embodiment, the ultrasonic generator includes a variable frequency triangular waveform generator coupled with a pulse width modulator. The output from the pulse width modulator is coupled with the gates of an IGBT, which amplifies the signal and delivers it to a coil that is used to drive a magnetostrictive transducer. In one embodiment, high voltage of 0-600 VDC is delivered across the collector and emitter of the IGBT after the signal is delivered. The output of the IGBT is then a square waveform with a voltage of ±600V. This voltage is sent to a coil wound around the ultrasonic transducer. The voltage creates a magnetic field on the transducer and the magnetostrictive properties of the transducer cause the transducer to vibrate as a result of the magnetic field. The use of the IGBT as the amplifying device obviates the need for a SCR circuit, which is typically used in low powered ultrasonic transducers, and which would get overheated and fail in such a high-powered and load-varying application.
[0009] For a further understanding of the nature and advantages of the invention, reference should be made to the following description taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a simplified circuit diagram showing a model of a full bridge IGBT circuit with a parallel resonant magneto-constrictive transducer according to one embodiment of the present invention.
[0011] FIG. 2 shows two pulse trains, which are mutually inverted and 180 degrees out of phase that drive the expansion and contraction of magneto-constrictive ultrasonic transducer of FIG. 1 .
[0012] FIG. 3 is a simplified diagram of a side view of an oval windowed magneto-constrictive transducer.
[0013] FIG. 4 is a simplified circuit diagram for a system implementing the full bridge IGBT driving circuit of FIG. 1 , where a microprocessor outputs a voltage corresponding to the operating frequency of the voltage controlled oscillator (VCO), according to one embodiment of the present invention.
[0014] FIG. 5 is a graph of an exemplary output power waveform produced by the power driving circuit of FIG. 4 .
DETAILED DESCRIPTION OF THE INVENTION
[0015] Prior to the invention of the present ultrasonic generator, the prior art ultrasonic generators relied on Silicon Controlled Rectifier (“SCR”) technology. In these generators, the SCRs pulse current through an ultrasonic probe at a frequency of about 17.5 kHz. At this fast switching frequency, the SCRs can easily become overheated and fail. To address this overheating problem, the SCRs require a forced turn off system commonly know in the field of power electronics as “Forced Commutation.” This means that when a signal is delivered to the system to turn on the SCR, it will remain on for a specified amount of time after that signal is turned off. It is possible through forced commutation to make the SCR turn off faster. This forced commutation is required for a faster switching frequency of 17.5 kHz. Often due to this process the SCR becomes weakened and fails. Another problem with the SCR systems is that a specific capacitor arrangement is needed in order to make the forced commutation occur. The result of these added capacitors is a significant loss of power. The ultrasonic generator as developed by the inventors herein, requires a small amount of capacitance and thus is more reliable than the commonly used SCR-based systems. For example, the inventors herein have compared the novel IGBT-based generator with one that uses the prior art SCR technology, and report that the while the SCR-based system for the ultrasonic probe required a total input of about 3800 Watts, the ultrasonic generator in accordance with the embodiments of the present invention produces better results with the ultrasonic probe using only 2800 Watts. In addition to being more efficient than the commonly used SCR systems, the components, namely the IGBTs, in the generator are less costly and more readily available than the SCRs.
[0016] The ultrasonic generator in accordance with the embodiments of the present invention uses an IGBT rather than an SCR. The IGBT serves as an amplifier to magnify a pulse signal sent to the gates of the IGBT. The pulse sent to the gates of the IGBT is created from a variable pulse width generator. In one embodiment, this pulse width generator uses a variable frequency triangle waveform generator whose signal is sent to a comparator circuit with a variable reference voltage. The result is that by adjusting the reference voltage in the comparator circuit, the pulse width changes. This portion (e.g., the variable pulse width generator) of the generator is sometimes used with IGBTs to control A.C. motors. The variable frequency/pulse width signal is sent to the gates of the IGBT to be magnified. Variable voltage (e.g., in the range between 0-600 VDC) is delivered across the collector and emitter of the IGBT after the signal is delivered. The output of the IGBT is then a square waveform with a voltage of ±600V. This voltage is sent to a coil wound around the ultrasonic transducer. The voltage creates a magnetic field on the transducer and the magnetorestrictive properties of the transducer cause the transducer to vibrate as a result of the magnetic field.
[0017] The power driving circuit for the ultrasonic transducer in accordance with the embodiments of the present invention represents an innovation over previous driving circuits for ultrasonic transducers. In the circuit, the power components include matched IGBTs in a full bridge power configuration. As used herein, a full bridge includes two half-bridge push pull amplifiers. Each half bridge is driven by an asymmetrical rectangular pulse train. The two pulse trains, that drive the full bridge are 180 degrees out of phase and inverted. The symmetry (e.g., percent of positive and negative pulse components) of the pulses that drive each half bridge section can be configured for any desired ultrasound output power.
[0018] The IGBT-based driving circuit in accordance with the embodiments of the present invention is described below in further detail. The IGBT circuit includes the following main components, namely: a DC power source; an IGBT; a Gate Driving Circuit; and a Closed Loop Current Sensing Circuit. Each of these components is described in further detail below.
[0000] DC Power Source
[0019] The DC power source as used herein may be any power source which rectifies and filters standard (e.g., 60 Hz) AC voltage to be a DC voltage. Generally this power conversion is accomplished by increasing the line frequency by use of a thyristor or other such device. The high frequency AC is then rectified and filtered using a capacitor tank and/or a DC choke to eliminate AC ripple. The DC power source needs sufficient power to operate the largest load that the ultrasonic probe may encounter. Typically a DC voltage of up to 0-600V is suitable with an ampere rating of 50 A giving a maximum of 30 kW. Larger systems may be used producing voltages of up to 1200V, however the maximum voltage rating of the IGBT, which is typically 1200V, needs to be taken into consideration.
[0020] The DC power source is ideally connected to the IGBT through a polar capacitor bank with a large value in order to reduce switching spikes due to the extremely high operating frequencies and high voltages. The DC capacitor is sufficiently rated to handle the maximum voltage in the system and any voltage spike that may occur.
[0021] The DC power source preferably has a variable voltage control to allow for voltage adjustment during different loading conditions. Also, the voltage adjustment will allow for the opportunity to run an ultrasonic transducer at a lower power level, if desired. In one embodiment, the voltage regulation can be a simple potentiometer style with a manual interface. Alternatively, the voltage regulation is achieved via an analog voltage or current applied to a sensor circuit, or a digitally programmed interface. It is also preferable for the power source to have a maximum current limit control which will prevent the system from overloading.
[0000] Isolated Gate Bipolar Transistor
[0022] An IGBT is used to invert a DC voltage into a pulsed bipolar rectangular waveform. IGBTs are most commonly used for motor control in variable frequency drives. The operation of an IGBT is similar to most other transistors in that a bus voltage is applied to the collector and emitter, while a signal is applied to its gate. The DC bus is then pulsed at the applied bus voltage and frequency and duty cycle of the gate signal.
[0023] An IGBT for use with a magnetostrictive transducer, such as exists in assignee's technology, can be sized depending on the loads on the transducer. During switching of the IGBT, large current spikes exist due to the magnetostrictive load being highly inductive. Thus, the IGBT used is often highly over rated for these current spikes. For example, a typical magnetostrictive transducer may require 9-10 Amps RMS. However, the current spikes may be as high as 300 Amps for only 1-2 microseconds during switching. Thus, a suitable IGBT for this type of operation should have a current rating of 300 A and a peak current rating of 600 A.
[0000] IGBT Gate Driving Circuit
[0024] An important aspect of the successful operation of the IGBT is the proper driving of its gate. Common methods for controlling IGBT gates used in motor control are not sufficient for operating the IGBT in use with a magnetostrictive ultrasonic probe. Generally, a motor control gate drive circuit attempts to simulate an alternating current similar to standard 50/60 Hz AC found in wall sockets. Thus, the IGBT is pulsed with a varying duty cycle at a very high frequency. At a low duty cycle (e.g., 10%) there is a small amount of current, then as the duty cycle increases the current also increases. When driving an IGBT for use with an ultrasonic probe a DC bias exists for successful operation. The amount of DC bias can be directly controlled in a full bridge system by varying the duty cycle of the various IGBT gates as shown in FIG. 2 . The amount of DC bias will increase with a higher duty cycle of pulse train A which in turn decreases the duty cycle of pulse train B accordingly so that the 2 different pulses are not high at the same time.
[0025] In order to produce this type of gate driving, a waveform generator is used. The waveform generator can be any standard waveform generator which is capable of varying the frequency and/or duty cycle of the generated waveform. In one embodiment of the gate driving circuit, a triangle waveform generator is used. For example, the triangle waveform is produced by an 8038 triangle waveform generator. The 8038 chip allows for pulse width control of the in phase and quadrature IGBT control waveforms, which impacts the power management of the full bridge IGBT circuit. In one embodiment, the driving circuit uses this circuit with variable frequency control and variable pulse width control. The triangle wave is sent to two LF 353 comparators that compare a preset voltage to the positive and negative triangle waveforms to generator the in phase and quadrature control waveforms for the full bridge IGBT circuit. The quadrature control waveforms for the full bridge IGBT circuit are generated such that while the positive triangle wave is greater than the preset voltage a pulse width controlled rectangular wave is generated, and while the negative triangle wave is less than the preset voltage the quadrature control rectangular wave is generated. In an alternate embodiment, the power driving circuit uses the Global Specialties 2 MHz waveform generator. This waveform generator may also use the basic 8038 triangle waveform generator with positive and negative comparators.
[0026] FIG. 1 is a simplified circuit diagram showing a model of a full bridge IGBT circuit with a parallel resonant magneto-constrictive transducer according to one embodiment of the invention. As shown in FIG. 1 , Q 1 , Q 2 , Q 3 , Q 4 are the 4 IGBT that compose the full bridge circuit shown. D 1 , D 2 , D 3 , D 4 are four protection diodes that prevent reverse current across the IGBT that would be damaging. L 1 and L 2 are the inductance of the windings of magneto-constructive transducer that is driven by the full bridge circuit. Only One winding is shown in the Full Bridge diagram of FIG. 1 . C 1 is a parallel capacitance that allows the magneto-constrictive to operate in resonance. However, in practice this capacitor can be left out because of small device parasitic capacitances that allow the magneto-constructive transducer to operate at resonance in the 15 KHz to 20 KHz region.
[0027] In operation, the full bridge circuit is driven by the gate driving pulse trains A and B, as shown in FIG. 2 . The first pulse train (Train A) is applied to the gates of IGBT Q 1 and Q 4 and the second pulse train (Train B) is applied to the gates of IGBT Q 2 and Q 3 .
[0028] As shown in FIG. 2 , the two pulse trains, are mutually inverted and 180 degrees out of phase to drive the expansion and contraction of magneto-constrictive ultrasonic transducer. These signals are optical isolated from the IGBT gates by optocoupler gate driver. Other IGBT driver protection circuitry limits the gate voltage and blocks this signal when the collector to emitter voltage is too high. The gate driver circuit also includes a buffer amplifier that provides several amps driving current.
[0029] FIG. 3 is a simplified diagram of a side view of an oval windowed magneto-constrictive transducer. Shown in FIG. 3 are the two windings that drive the ultrasonic magneto-constrictive transducer. These windings are driven in parallel by the IGBT power source at the optimum frequency of operation. The first output of the full bridge connects to the center-tap of the each half bridge on Q 1 and Q 3 . The second output of the full bridge connects to the center tap outputs of the half bridges Q 2 and Q 4 . For this power pulse configuration the magnetic flux through the magneto-constructive torroidal ring is in phase. For the configuration shown in FIG. 3 , the two windings are in opposite senses.
[0030] In operation, the circuit of FIGS. 1-3 enable a new method of driving the ultrasonic transducer. The full bridge method of driving the ultrasonic transducer is shown in FIGS. 1, 2 and 3 . The two half bridge circuits of the full bridge IGBT system each drive the transducer magneto-constrictive material to a contracted state (negative pulse) and to an expanded state (Positive Pulse). Other safety components included in the full bridge design and not shown in FIG. 1 are input snubber capacitors across the DC power input to the two half bridge IGBT circuits as shown in FIG. 1 . In the circuit of FIG. 1 , IGBT are the solid state device of choice for the Low Frequency region of 15 KHz to 20 KHz. Alternately, Mosfet devices are used in the 200 KHz to 300 KHz regions for ultrasonic chemical processing.
[0031] Because the IGBT relies on rectangular power pulses, the fast current changes in the inductor produce L*dI/dT caused voltage spikes. The problem of high voltage spikes requires IGBT with high voltage capacities above the average operating voltage in the resonant transducer circuit. While the full bridge parallel resonant driver is more power efficient than the SCR driven ultrasonic transducer, it produces spikes, while an SCR-based system does not produce voltage spikes. This is because the SCRs are only actively triggered in the positive state and are turned off in the commutation mode where the transducer resonates in the commutative mode.
[0032] FIG. 4 is a simplified circuit diagram for a system implementing the full bridge IGBT driving circuit of FIG. 1 , where a microprocessor outputs a voltage corresponding to the operating frequency of the voltage controlled oscillator (VCO), according to one embodiment of the invention. The microprocessor scans over the operating frequency range and records through the serial port connection to the DC power generator the corresponding RMS current in amperes going to the ultrasonic transducer. After scanning over the frequency range (e.g., from 16 KHz to 18 KHz) and recording the power current at each step, the microprocessor selects the voltage corresponding to maximum power and locks in this operating frequency value. In a batch reactor this optimization process takes place at the beginning of each batch cycle. After the operating frequency is set, the peak resonant voltage is set to a point below the IGBT breakdown voltage by raising or lowering the pulse train duty cycle.
[0033] In operation, the circuit of FIG. 4 enables a new method of controlling the operating frequency of an ultrasonic magneto-constrictive transducer to respond to changes in characteristics of the magneto-constrictive material, in response to temperature changes in the ultrasonic reactor. This control scheme uses a microprocessor with D/A and A/D capacities. In another embodiment, instead of the microprocessor, a Programmable Logic Controller (PLC) is used. The microprocessor or controller samples (Through A/D port) the maximum voltage, or peak envelope, voltage. The peak envelope voltage is used by the microprocessor to control the average driving power pulse width. The on time of the positive and negative pulse trains in FIG. 2 are limited so the voltage spikes do not go over the limiting breakdown voltage of the IGBT. In order to set the resonate transducer frequency, the average DC input current is read through the serial port of the DC power generator by the serial port of the microprocessor or PLC. In one embodiment, the maximum RMS current of the deflection transducer or passive magneto-constrictive element is read as the operating frequency is scanned to optimize the ultrasonic vibration frequency. Preferably, the microprocessor or controller scans the operating frequency region for 16 KHz to 18 KHz by increasing the voltage controlled Oscillator output voltage (through the d/a port). At each scanning frequency the RMS current in amperes is sensed and recorded through the serial port. After the operating frequency is set the pulse width can be raised or lowered so the resonant voltage does not go over the IGBT breakdown voltage.
[0034] FIG. 5 is a graph 500 of an exemplary output power waveform produced by the power driving circuit in accordance with the embodiments of the present invention. The square wave 502 shows the 0 to 400 volts that is drawn from the microprocessor controlled DC voltage supply. +200 and −200 volts are drawn by each side of the Full Bridge power circuit. The lower wave form 504 shows the total real and reactive current wave form. The reactive component of the current waveform can be found from the equation V=L*di/dt, where L is the inductance of the double coils wound on the looped magnetostrictive magnets. The total RMS current drawn is 20 Amps. This current gives the total real power of approximately 4 KWatt. The wave form shows current of 0 to 60 amps. The reactive current goes into the reactive power that is used to maintain the vibrations in the magnetostrictive laminated core and in the transducer base and wear tip. The loss in the core is caused by eddy current losses. For the 2-inch core consisting of 500 4 mil laminations, the total loss in approximately 300 Watts, that is lost as Heat. The real losses in the transducer base and wear tip occur from the power required to act against gravity and the mechanical loss in the base and wear tip, that also contribute to the lost heat.
[0035] In one embodiment, the voltage controlled oscillator is based on an 8038 chip which generates a full cycle square wave with positive and negative rectangular components. The output from the voltage controlled oscillator is separated into two positive and negative pulse trains as shown in FIG. 2 by passing the full cycle wave into positive and negative powered operational amplifiers using two fast LF353 chips. Inverting and non-inverting amplifiers raise the peak positive and negative pulse voltage to the 15 volts required by the four IGBTs. Alternately, a commercial waveform generator that is accessible to computer control by the RS 232 port can be used in a power optimization scheme instead of the VCO.
[0036] In an alternate embodiment, a VCO is not used. Instead of a VCO, a Hall effect sensors detect the positive and negative going zero current crossings. At the positive current crossing a Positive pulse is sent to the base of Q 1 and Q 4 in FIGS. 1 and 4 at the negative going zero current crossing a negative pulse is sent to the base of the Q 2 and Q 3 IGBTs.
[0037] As will be understood by those skilled in the art, other equivalent or alternative methods and circuits for driving a high-power and variable-load ultrasonic transducer according to the embodiments of the present invention can be envisioned without departing from the essential characteristics thereof For example, the IGBT gates may be driven by a pulse train produced by any suitable wave generating device or system as described above. Accordingly, the foregoing disclosure is intended to be illustrative, but not limiting, of the scope of the invention which is set forth in the following claims.
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The present invention is directed to a high-powered (e.g., >500 W) ultrasonic generator for use especially for delivering high-power ultrasonic energy to a varying load including compressible fluids. The generator includes a variable frequency triangular waveform generator coupled with pulse width modulators. The output from the pulse width modulator is coupled with the gates of an Isolated Gate Bipolar Transistor (IGBT), which amplifies the signal and delivers it to a coil that is used to drive a magnetostrictive transducer. In one embodiment, high voltage of 0-600 VDC is delivered across the collector and emitter of the IGBT after the signal is delivered. The output of the IGBT is a square waveform with a voltage of ±600V. This voltage is sent to a coil wound around the ultrasonic transducer. The voltage creates a magnetic field on the transducer and the magnetorestrictive properties of the transducer cause the transducer to vibrate as a result of the magnetic field. The use of the IGBT as the amplifying device obviates the need for a Silicon Controlled Rectifier (SCR) circuit, which is typically used in low powered ultrasonic transducers, and which would get overheated and fail in such a high-powered and load-varying application.
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FIELD OF THE INVENTION
[0001] The present invention relates to a garment in which the width of an opening is adjustable by means of a cord or drawstring having free ends accessible by the wearer which ends are usually tied together to maintain the desired adjustment and to a cover comprising means to retain the tied ends of the cord or drawstring within the garment during activity by the wearer.
BACKGROUND OF THE INVENTION
[0002] It is commonplace for the waists of trousers, shorts or skirts and other types of clothing to be reduced in width by adjusting a belt. It is also known for such garments, particularly those used in sports, i.e., soccer, wrestling, etc., to employ a drawstring which is confined within the waistband of the garment with the ends passing through an aperture on the inside of the waistband at the front of the garment whereby the wearer is able to grasp the ends of the drawstring and pull them to adjust the waistband to fit, whereupon the ends of the drawstring are tied, usually in a bow, and tucked in between the garment and the wearer's body.
[0003] In such circumstances it is not unusual for the tied ends of the drawstring to work their way out from between the inside of the waistband and the wearer's body and to become exposed such that they may become untied or, in the case of a close contact sport such as wrestling, inadvertently entangled in an opponent's fingers.
[0004] Thus there is perceived a need for a means to comfortably retain the tied ends of a drawstring in place within a garment during physical activity which does not add bulk around the waist of the garment and which does not present discomfort or danger to the wearer.
SUMMARY OF THE INVENTION
[0005] Accordingly, the present invention provides an item of clothing in which the width of an opening therein is adjustable by means of a drawstring confined within a band encircling the opening, the drawstring having exposed ends whereby the width of the opening is adjustable by pulling on the ends of the drawstring, the ends being secured by tying them together, the item of clothing further having a drawstring cover in the form of a flap or panel secured along one edge to the band encircling the opening adjacent to and above the ends of the drawstring, this flap or panel being positionable over the tied ends of the drawstring between the band and the wearer's body to cover and confine the tied ends of the drawstring. The flap or panel is secured to the band in such a manner that, in its relaxed state, the panel hangs downward within the garment over the drawstring ends.
[0006] Preferably, the surface of the flap or panel which lies against the drawstring ends and the inside of the garment has a texture which provides a high degree of friction with the fabric of the garment and the drawstring to ensure retention of the flap or panel in its correct position within the garment, thereby ensuring confinement of the ends of the drawstring. The surface of the flap or panel which lies against the wearer's body is preferably smooth and non-irritating to the skin.
[0007] In its simplest form, the flap or panel is s single layer of fabric sewn into the band above the drawstring along one edge of the panel. Alternatively, the flap or panel may be two layers of fabric sewn together with an intermediate layer of stiffening material, such as Pelon which is a fusible liner material commonly used to provide structure to shirt collars and the like. Also, if desired, a layer of padding, such as foam or non-woven batting may be provided between the two layers of fabric as a cushion between the tied ends of the drawstring and the wearer's body. In a still further embodiment, the flap or panel may be provided with a pouch or pocket on the drawstring side into which the tied ends of the drawstring may be tucked for added security.
[0008] The present invention is particularly suitable for use with drawstrings used to adjust the waist size of a garment but may be used anywhere a drawstring is used where the ends of the drawstring are accessed from within the garment.
[0009] Thus, it is an object of this invention to provide a garment comprising an adjustable waistband, a cord within the waistband, the cord having two ends passing out of the waistband through at least one opening therein within the garment and accessible to a wearer whereby the cord can be pulled by the wearer to adjust the size of the waistband about the wearer, the ends of the cord being tieable to maintain the adjusted size, cover means secured to the waistband adjacent to the at least one opening and positionable over the tied cord between the garment and the wearer whereby the tied cord is confined between the garment and the cover means whereby eversion of the tied cord from between the garment and the wearer is prevented.
[0010] It is a further object to provide a garment having a circumferentially adjustable opening, a band encircling the opening on the inside of the garment and confining a cord therein, an aperture in the band, the cord extending about the opening within the band and having two free ends passing through the aperture whereby the cord is adjustable by pulling on the ends, the ends being securable by tying them together, the improvement comprising:
[0011] a fabric panel having a first side and a second side, the panel being secured along an edge thereof to the band between the opening and the aperture, whereby the panel is normally positioned over the aperture whereby the ends of the cord are confined between the first side of the panel and the inside of the garment and whereby the panel is displaceable outward of the garment to provide access to the cord ends.
[0012] It is a still further object to provide a drawstring cover for a garment having a waistband adjustable by means of a drawstring the ends of which pass through an aperture in the waistband and are accessed from within the garment for adjustment and tying, the drawstring cover comprising a fabric panel secured to the waistband along an edge of the panel between the aperture and the outer edge of the waistband, the panel adapted to hang downward within the garment over the ends of the drawstring between the drawstring and a wearer, whereby the panel covers and confines the drawstring whereby the tied drawstring is prevented from being inadvertently everted or pulled from within the garment.
[0013] Further objects and advantages will become evident from the following drawings and descriptions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 . is an expanded view showing the present invention in a garment.
[0015] FIG. 2 . is a planar view of the inside of a garment with the drawstring cover in place.
[0016] FIG. 3 . is a view of the inside of a garment showing an alternative embodiment of the drawstring cover having a pocket for receiving the ends of the drawstring.
[0017] FIG. 4 . shows the embodiment of FIG. 3 with the drawstring tucked into the pocket.
[0018] FIG. 5 . is a cross section showing the first stage of construction of a garment according to the present invention.
[0019] FIG. 6 . is a cross section along line A-A of FIG. 2 showing the construction of a garment according to the present invention.
[0020] FIG. 7 . is a cross section along line A-A of FIG. 2 showing the construction of a garment with the alternative embodiment of FIG. 3 .
[0021] FIG. 8 . is a view of the inside of a garment showing an alternative embodiment of the pocket for receiving the ends of the drawstring.
[0022] FIG. 9 is a cross section along line A-A of FIG. 2 showing the construction of the embodiment of FIG. 8 .
DETAILED DESCRIPTION OF THE INVENTION
[0023] Looking at FIG. 1 , the present invention provides a drawstring cover 1 which is sewn into a garment 2 with a waistband 3 and a drawstring 4 . In the normal construction of a drawstring garment, the waistband 3 and garment 2 are sewn together along stitching lines 5 and 6 so that a space 18 is left between them to accommodate the drawstring 4 . An aperture 7 is provided in the waistband 3 , usually at the inside front of the garment, through which the ends 8 of the drawstring pass so as to be accessible to the wearer.
[0024] In an ordinary drawstring garment, the garment is donned by the wearer and the ends 8 of the drawstring 4 are pulled to adjust the fit of the garment about the wearer's waist. The ends 8 of the drawstring are then tied together to retain the adjustment and the tied ends 8 are simply tucked inside the garment between the waistband 3 and the wearer's body. In this position, there is nothing to keep the tied ends of the drawstring inside the garment and it is often the case that simple movements by the wearer cause the tied ends to be everted where they can become loosened and entangled.
[0025] In its simplest embodiment shown in FIG. 1 , drawstring cover 1 is sewn into a finished garment 2 along stitching line 9 which preferably coincides with stitching line 5 and hangs downward over waistband 3 and tied ends 8 of drawstring 4 . In this embodiment, drawstring cover 1 comprises a single layer of fabric which may be the same as that used to manufacture garment 2 . To bias drawstring cover 1 in its downward position, the tack stitches 10 are applied at each end of stitching 9 securing drawstring cover to waistband 3 below the location of drawstring 4 . In this manner, the upper edge 12 and the upper ends of the sides of drawstring cover 1 at the tack stitches 10 form a downwardly opening pouch over drawstring ends 8 which physically prevents drawstring ends 8 from being everted from their tucked in position within garment 2 .
[0026] As noted, drawstring cover 1 in this embodiment is a single layer of fabric which may be the same as that used to manufacture garment 2 or such other fabric as is desired. Examples include but are not limited to cotton, polyester, nylon, and other natural or synthetic fibers including blends thereof. Preferably, any fabric used should have at least one side that is comfortable and non-irritating to human skin and that side will be outermost in the completed construction. The opposite side facing garment 2 and drawstring ends 8 may have a texture which provides a high coefficient of friction against garment 2 and drawstring ends 8 to resist sliding against garment 2 thereby improving the ability of drawstring cover 1 to remain in place over drawstring ends 8 . As an alternative, patches of hook and loop fastener material 11 may be used along the lower edge of drawstring cover 1 with corresponding portions on the inside of garment 2 , as shown in FIG. 6 , to ensure that drawstring cover 1 remains in place during physical activity. For drawstrings in locations other than a garment waist, more rigid fasteners such as snaps or buttons may be used.
[0027] Drawstring cover 1 is of sufficient size and shape to permit securing to garment 2 in the manner described and to provide the desired coverage over drawstring ends 8 . A substantially rectangular panel of 3 to 6 inches along each side is suitable. Alternatively, drawstring cover 1 may be semicircular as shown in the drawing figures with attachment to garment 2 being along the straight edge 12 . Of course, drawstring cover 1 may be provided in any shape desired as long as it provides the desired function.
[0028] Although drawstring cover 1 in its simplest form comprises a single layer of fabric, in order to obtain a comfortable, non-irritating outer face and a textured inner face, drawstring cover 1 may comprise two layers of dissimilar fabric secured together about their common peripheries. In this construction, if desire, a layer of padding, such as foam or non-woven batting, or a fabric stiffener, such as pelon, may be provided between the inner and outer fabric layers.
[0029] The foregoing describes a garment construction wherein the drawstring cover 1 is simply sewn directly to the waist of a completed garment 2 so as to be in place over the drawstring ends 8 . Preferably, however, drawstring cover 1 is included during the construction of garment 2 as shown in FIGS. 5 and 6 .
[0030] FIG. 5 shows a cross section of the first stage of this construction with waistband 3 , drawstring cover 1 and garment 2 sewn together along stitching lines 5 in a layered assembly which is the partially assembled garment turned inside out. As shown in FIG. 6 , this assembly is then turned right side out by folding garment 2 over stitching lines 5 and the sewn together ends of drawstring cover 1 , garment 2 and waistband 3 . Drawstring 4 is placed in the space 18 between waistband 3 and garment 2 with the ends 8 threaded through aperture 7 and waistband 3 and garment 2 are sewn together along stitching lines 6 . Alternatively, waistband 3 and garment 2 may be sewn together along stitching lines 6 , thereby creating space 18 and drawstring threaded through aperture 7 and space 18 so that both ends 8 extend outward through aperture 7 .
[0031] FIG. 6 shows the above construction of the single fabric layer embodiment as a cross section along line A-A of FIG. 2 . In an alternative embodiment which is a variation of the double layer construction described previously, the second or inner layer 13 can be used to form a pocket on drawstring cover 1 in which the ends 8 of drawstring 4 may be tucked for further security. This embodiment is shown in FIGS. 3 and 4 and in cross section in FIG. 7 where second layer 13 is shorter than drawstring cover 1 and the two layers are sewn together around their common peripheral edges 14 . The top edge 15 of second layer 13 is not sewn so that a pocket 16 is formed between drawstring cover 1 and second layer 13 . As shown in FIGS. 4 and 7 , drawstring ends are tucked into pocket 16 with drawstring cover 1 everted. Drawstring cover 1 is then folded downward between garment 2 and wearer to securely confine drawstring ends 8 .
[0032] In a further embodiment, shown in FIGS. 8 and 9 , drawing cover 1 and second layer 13 are separate fabric layers of the same size and shape sewn together along their common peripheral edges at 14 . Access to pocket 16 is by means of a slit 17 cut across part of second layer 13 below stitch lines 5 . Edges of slit may be reinforced by whip stitching as in button holes or by such other means as are known. In this embodiment, drawstring ends 8 are tucked into pocket 16 through slit 17 and drawstring cover 1 is then tucked downward in between garment 2 and wearer.
[0033] While the invention has been described with respect to certain specific embodiments, it will be appreciated that many modifications and changes may be made by those skilled in the art without departing from the spirit of the invention. It is intended, therefore, by the appended claims to cover all such modifications and changes as fall within the true spirit and scope of the invention.
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The present invention relates to a garment in which the width of an opening is adjustable by means of a cord or drawstring having free ends accessible by the wearer which ends are usually tied together to maintain the desired adjustment and to a cover comprising means to retain the tied ends of the cord or drawstring within the garment during activity by the wearer.
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CLAIM OF PRIORITY
[0001] This application claims priority of prior provisional Application Ser. No. 60/541,882 filed Feb. 4, 2004.
TECHNICAL FIELD
[0002] This invention relates generally to fence posts, and more particularly to an improved fence post design which is both easier to use and more pleasing in appearance as compared with traditional fence posts.
BACKGROUND AND SUMMARY OF THE INVENTION
[0003] Over the centuries fence posts have been manufactured from a wide variety of materials including unprocessed sticks and tree limbs, various wooden configurations manufactured by conventional wood processing techniques, metal tubes formed from iron, steel, and other metals, etc. A fence post design that is currently in wide spread use is formed from steel and is T-shaped in horizontal cross section. Protrusions are provided at equally spaced intervals along the length of the fence post to facilitate alignment of fence wires therewith.
[0004] One difficulty that has heretofore been common to all fence post designs comprises the fact that a fastener of some type is necessary in order to secure each fence wire to each fence post. In the case of wooden fence posts, nails or cleats can be used to secure the fence wires to the fence post. In the case of the T-shaped fence post described above, clips are received around the fence wires and the fence post. The opposite ends of the clips are then twisted around one another to secure the fence wires in place.
[0005] As will therefore be understood, the construction of a fence utilizing conventional fence post designs entails considerable expense due to the fact that each fence wire must be manually attached to each fence post. An additional difficulty involves the fact that the necessity of utilizing fasteners to attach fence wires to fence posts often results in a fence construction which is unsightly in appearance.
[0006] The present invention comprises an improved fence post design which overcomes the foregoing and other difficulties which have long sense characterized the prior art. In accordance with the broader aspects of the invention, one or more side walls define an interior which may be open, partially enclosed, or fully enclosed. Nominally horizontally disposed slots are formed through the side wall and into the interior of the fence post. The horizontally disposed spots are located at equally spaced intervals along substantially the entire length of the fence post.
[0007] In use, the fence post is driven into the ground in a nominally vertical orientation. Fence wires are positioned in some or all of the horizontally disposed slots comprising the fence post. The fence wires are fully seated in the slots after which a keeper rod is extended through the interior of the fence post between the wall of the fence post and the fence wires thereby retaining the fence wires within the horizontally disposed slots.
[0008] In the case of an electrified fence, wire receiving inserts formed from an electrically insulating material are received in the horizontally disposed slots comprising the fence post. The fence wires are received in the inserts and are retained by keeper rod which is either formed from or covered with an insulating material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] A more complete understanding of the present invention may be had by reference to the following Detailed Description when taken in connection with the accompanying Drawings, wherein:
[0010] FIG. 1 is a perspective view illustrating a fence post comprising a first embodiment of the present invention;
[0011] FIG. 2 is a sectional view taken along the line 2 - 2 in FIG. 1 in the direction of the arrow;
[0012] FIG. 3 is a perspective view illustrating a second embodiment of the invention;
[0013] FIG. 4 is a perspective view illustrating a third embodiment of the invention;
[0014] FIG. 5 is a perspective view illustrating a fourth embodiment of the invention; and
[0015] FIG. 6 is a perspective view illustrating a fifth embodiment of the invention which is particularly adapted for use in conjunction with electrified fences.
[0016] FIG. 7 is a perspective view illustrating a sixth embodiment of the invention;
[0017] FIG. 8 is a perspective view illustrating a seventh embodiment of the invention;
[0018] FIG. 9 is a perspective view illustrating an eighth embodiment of the invention;
[0019] FIG. 10 is a perspective view illustrating one embodiment of the horizontal slots which are used in the practice of the invention; and
[0020] FIG. 11 is a perspective view illustrating a second embodiment of the horizontal slots which are used in the practice of the invention.
DETAILED DESCRIPTION
[0021] Referring now to the Drawings, and particularly to FIGS. 1 and 2 thereof, there is shown a fence post 10 comprising a first embodiment of the invention. The fence post 10 comprises a wall 12 defining an interior 14 . The wall 12 of the fence post 10 comprises a unitary construction formed from steel or any other high strength, weather resistance material, however, multiple component walls may also be used in the practice of the invention. The interior 14 defined by the wall 12 may be either open as shown in FIGS. 1 and 2 , or partially closed, or fully closed depending upon the requirements of particular applications of the invention.
[0022] Referring specifically to FIG. 1 , the lower end of the fence post 10 comprises a beveled point 16 . The beveled point 16 facilitates insertion of the fence post 10 into the ground. As will be appreciated by those skilled in the art, other types and kinds of lower end configurations for the fence post 10 may be utilized in the practice of the invention dependent upon the requirements of particular applications thereof.
[0023] The lower end of the fence post 10 is also provided with a spade 18 . The function of the spade 18 is to prevent removal of the fence post 10 after it is installed in the ground. The spade 18 also functions to prevent rotational movement of the fence post 10 in the vertical plane following installation thereof.
[0024] Referring specifically to FIG. 2 , the wall 12 comprises a v-shaped front section 20 which extends to spaced, parallel side sections 22 . The side sections 22 in turn extend to flanges 24 which extend perpendicularly outwardly from the side sections 22 . The wall 12 has a height H 1 which is configured for optimal resistance to bending in the direction extending parallel to the wall 12 . The configuration of the wall 12 as shown in FIG. 2 provides an interior 14 which is entirely open. As will be appreciated by those skilled in the art, the flanges 24 can also extend inwardly from the wall sections 22 thereby providing an interior 14 which is partially enclosed. The flanges 24 can also extend inwardly from the wall sections 22 a sufficient distance to engage one another in which case the interior 14 is entirely enclosed.
[0025] The fence post 10 differs from prior fence post designs in that the fence post 10 is provided with a plurality of nominally horizontally disposed slots 30 . As is best shown in FIG. 2 , each of the slots 30 extends through the wall 12 comprising the fence post 10 and into the interior 14 thereof. As is best shown in FIG. 1 the slots 30 are located at equally spaced intervals along substantially the entire length thereof. Although the slots 30 are illustrated in the drawings as being equally spaced, the fencepost 10 may also be manufactured with the slots 30 unequally spaced. As will be understood by those skilled in the art, it is not necessary to provide slots 30 in the portion of the fence post 10 that will be underground following installation thereof. However, the slots 30 may be provided at equally spaced intervals along the entire length of the fence post 10 depending upon the particular process that is utilized in the manufacture of the fence post 10 .
[0026] Utilization of the fence post 10 begins with installation of the fence post into the ground. The fence post 10 is installed using any of a variety of well know fence post installation techniques. The fence post 10 is typically installed in a nominally vertical or plumb orientation, however, other orientations of the fence post 10 may be utilized depending upon the requirements of particular applications thereof.
[0027] The following installation of the fence post 10 in the ground, fence wires 32 are installed in one or more of the slots 30 . Each fence wires 32 is fully seated in its corresponding slot 30 . Following the positioning of the fence wires 32 in the slots 30 , a keeper rod 34 is extended through the interior 14 of the fence post 10 between the wall 12 and the fence wires 32 . The keeper rod 32 may be formed from the same material that is utilized in the manufacture of the fence post 10 and/or the fence wires 32 . Alternatively, the keeper rod 34 may be formed from steel or other metals, fiberglass, various plastics and other polymerics, and other materials, provided only that the keeper rod 34 is sufficiently strong and tough to resist breakage during utilization of a fence that is constructed from fence post comprising the present invention and sufficiently resistant to deterioration due to weather.
[0028] In actual practice the keeper rod 34 may be installed by first pushing the uppermost fence wire 32 into its corresponding slot 30 as far as possible, inserting the keeper rod 34 into the upper end of the fence post 10 until it moves past the uppermost fence wire 32 and the uppermost slot 30 , thereafter pushing the next lower fence wire 32 as far as possible into its corresponding slot 30 , moving the keeper rod 34 downwardly until it is past the second fence wire 32 and its corresponding slot 30 , etc. When the keeper rod 34 is fully seated in the fence post 10 thereby retaining all of the fence wires 32 in their respective slots 30 , the upper end of the keeper rod 34 is typically aligned with the upper end of the fence post 10 . However, as will be appreciated by those skilled in the art, it is also possible to move the upper end of the keeper rod 34 further downwardly relative to the fence post 10 provided only that the upper end of the keeper rod 34 has not moved downwardly sufficiently to disengage the keeper rod 34 from the uppermost fence wire 32 .
[0029] Referring to FIG. 3 there is shown a fence post 40 comprising a second embodiment of the invention. Many of the component parts of the fence post 40 are substantially identical in construction and function to component parts of the fence post 10 illustrated in FIGS. 1 and 2 and described hereinabove in conjunction therewith. Such identical component parts are designated in FIG. 3 with the same reference numerals utilized above in the description of the fence post 10 , but are differentiated therefrom by means of a prime (′) designation.
[0030] The fence post 40 comprises a triangularly shaped wall 42 . The wall 42 comprises three interconnected panels 42 a , 42 b and 42 c. As will be appreciated by those skilled in the art, when the wall 42 c is utilized the interior 14 ′ of the fence post 40 is completely enclosed. However, the wall 42 c may be dispensed with entirely in which case the interior 14 ′ of the fence post 40 is open. The wall 42 c can also comprise inwardly turned flanges in which case the interior 14 ′ Lastly, the wall 42 c can comprise outwardly turn flanges similar to the flanges 24 of the fence post 10 as shown in FIG. 2 and described hereinabove in conjunction therewith.
[0031] Referring to FIG. 4 there is shown a fence post 50 comprising a third embodiment of the invention. The fence post 50 includes numerous component parts which are substantially identical in construction and function to component parts of the fence post 10 illustrated in FIGS. 1 and 2 and described hereinabove in conjunction therewith. Such identical component parts are designated in FIG. 4 with the same reference numerals utilized in the description of the fence post 10 but are differentiated therefrom by means of a prime (′) designation.
[0032] The fence post 50 differs from the fence post 10 of FIGS. 1 and 2 in that the fence post 50 comprises a wall 52 which is square or rectangular in configuration. The horizontally disposed slots 30 ′ extend into the wall 52 through one corner 54 thereof thereby extending into the interior 14 ′ of the fence post 50 .
[0033] A fence post 60 comprising a fourth embodiment of the invention as illustrated in FIG. 5 . Many of the component parts of the fence post 60 are substantially identical in construction and function to component parts of the fence post 10 as illustrated in FIGS. 1 and 2 and described hereinabove in conjunction therewith. Such identical component parts are designated in FIG. 5 with the same reference numerals utilized in conjunction with the description of the fence post 10 but are differentiated therefrom by prime (′) designation.
[0034] The fence post 60 differs from the fence post 10 in that the wall 62 thereof is round. Thus, the wall 62 may comprise a length of pipe formed from steel or other metals, fiberglass, polyvinylchloride (PVC) and other polymerics, etc. with the only requirements for the selection of the material to be utilized in the construction of the wall 62 being sufficient strength and weather resistance to meet the requirements of particular applications of the invention. As will also be appreciated by those skilled in the art, the cross section of the wall 62 is not necessarily round, but can be oval, etc.
[0035] FIG. 6 illustrates a fence post 70 comprising a fifth embodiment of the invention. Many of the component parts of the fence post 70 are substantially identical in construction and function to component parts of the fence post 10 illustrated in FIGS. 1 and 2 and described hereinabove in conjunction therewith. Such identical component parts are designated in FIG. 6 with the same reference numerals utilized in the description of the fence post 10 but are differentiated therefrom by means of a prime (′) designation.
[0036] The fence post 70 is particularly adapted for use with fences in which the fence wires 72 are electrified. Rather than being received directly in the horizontally disposed slots 30 ′, the electrified fence wires 72 are received in inserts 74 which are formed from an insulating material. The inserts 74 are in turn received in the slots 30 ′ formed in the wall 12 ′ comprising the fence post 70 . The fence post 70 further differs from the fence post 10 in that the keeper rod 76 is either formed from an insulating material or is coated with an insulating material. Thus, by means of the inserts 72 and the construction of the keeper rod 76 , the electrified fence wires 32 ′ are entirely isolated from the wall 12 ′ of the fence post 70 thereby preventing grounding of the electrified wires 32 ′.
[0037] FIG. 7 illustrates a fence post 80 comprising a sixth embodiment of the invention. Many of the component parts of the fence post 80 are substantially identical in construction and function to component parts of the fence post 10 illustrated in FIGS. 1 and 2 and described hereinabove in conjunction therewith. Such identical component parts are designated in FIG. 7 with the same reference numerals utilized in the description of the fence post 10 but are differentiated therefrom by means of a prime (′) designation.
[0038] The fence post 80 differs from the fence post 10 of FIGS. 1 and 2 in that the fence post 80 comprises side sections 22 ′ which are not perpendicular, but extend from the v-shaped front section 20 ′ side section 22 ′ construction enables the fence post 80 to be manufactured more easily as compared with the perpendicular side sections 22 .
[0039] FIG. 8 illustrates a fence post 90 comprising a seventh embodiment of the invention. Many of the component parts of the fence post 90 are substantially identical in construction and function to component parts of the fence post 10 illustrated in FIGS. 1 and 2 and described hereinabove in conjunction therewith. Such identical component parts are designated in FIG. 8 with the same reference numerals utilized in the description of the fence post 10 but are differentiated therefrom by means of a prime (″) designation.
[0040] The fence post 90 differs from the fence post 10 of FIGS. 1 and 2 in that the fence post 90 comprises shorter side sections 22 ″. As a result of the shorter side sections 22 ″, the wall 12 ″ has a height H 2 . The shorter wall 12 ″ requires less raw material and is therefore less expensive to manufacture than embodiments having the taller wall 12 , having height Hi. Although the shorter wall 12 ″ does not provide the same bending resistance as the taller wall 12 , the strength sacrificed is minimal and does not impact the intended performance or durability of the fence post 90 .
[0041] FIG. 9 illustrates a fence post 100 comprising an eighth embodiment of the invention. Many of the component parts of the fence post 100 are substantially identical in construction and function to component parts of the fence post 10 illustrated in FIGS. 1 and 2 and described hereinabove in conjunction therewith. Such identical component parts are designated in FIG. 9 with the same reference numerals utilized in the description of the fence post 10 but are differentiated therefrom by means of a prime (″) designation.
[0042] The fence post 100 differs from the fence post 10 of FIGS. 1 and 2 in that the fence post 100 comprises side sections 22 ″ which are not perpendicular, but extend from the v-shaped front section 20 ″ at an angle. Additionally, the side sections 22 ″ are shorter in height than the side sections 22 of fence post 10 . The wall 12 ″ has a height H 2 , requiring less raw material for the manufacture thereof. The shorter wall 12 ″ and the angled side sections 22 ″ present an embodiment which is more easily manufactured and at lesser cost as compared with other embodiments of the invention described herein.
[0043] FIG. 10 illustrates a portion of the embodiment shown in FIG. 1 . The fence post 10 is provided with a plurality of nominally horizontally disposed slots 30 having a width W 1 . Slots 30 having width W 1 are sized appropriately for receiving a varying sizes of fence wire.
[0044] FIG. 11 illustrates a portion of the embodiment shown in FIG. 1 . Many of the component parts of the fence post 110 are substantially identical in construction and function to component parts of the fence post 10 illustrated in FIGS. 1, 2 , and 10 and described hereinabove in conjunction therewith. Such identical component parts are designated in FIG. 11 with the same reference numerals utilized in the description of the fence post 10 but are differentiated therefrom by means of a prime (″′) designation.
[0045] The fence post 110 differs from the fence post 10 of FIGS. 1, 2 , and 10 in that the fence post 110 comprises nominally horizontally disposed slots 30 ″′ having a width W 2 which is substantially greater than width W 1 . Slots 30 ″′ having width W 2 accommodate more easily accommodate misalignments of fence wires used in the practical of the invention.
[0046] 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, but is capable of numerous rearrangements, modifications, and substitutions of parts and elements without departing from the spirit of the invention.
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A nominally vertically disposed fence post comprises a wall defining an interior. A plurality of nominally horizontally disposed slots are located at equally spaced intervals along the length of the fence post and extend through the wall into the interior thereof. Selected slots receive fence wires therein. A keeper rod extends through the interior of the fence post between the wall and the fence wires to retain the fence wires in the slots. Electrified fence wires are each received in an insulated insert which is received in one of the slots and are retained therein by an insulated keeper rod.
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CROSS REFERENCE TO RELATED APPLICATIONS
The priority of Korean Application No. 10-2001-0078244, filed Dec. 11, 2001, as well as U.S. Ser. No. 60/348,452, filed Jan. 16, 2002, U.S. Ser. No. 60/381,503, filed May 17, 2002, U.S. Ser. No. 60/407,741, filed Sep. 3, 2002, and U.S. Ser. No. 10/303,260, filed Nov. 25, 2002 are claimed. This Application is a continuation in part of Ser. No. 10/303,260, filed Nov. 25, 2002 now ABN.
BACKGROUND
Therapeutic proteins which are generally administered by intravenous injection may be immunogenic, relatively water insoluble, and may have a short in vivo half-life. The pharmacokinetics of the particular protein will govern both the efficacy and duration of effect of the drug. It has become of major importance to reduce the rate of clearance of the protein so that prolonged action can be achieved. This may be accomplished by avoiding or inhibiting glomerular filtration which can be effected both by the charge on the protein and its molecular size (Brenner et al., (1978) Am.J.Physiol.,234,F455). By increasing the molecular volume and by masking potential epitope sites, modification of a therapeutic polypeptide with a polymer such as polyethylene glycol (PEG) has been shown to be efficacious in reducing both the rate of clearance as well as the antigenicity of the protein. Reduced proteolysis, increased water solubility, reduced renal clearance, and steric hindrance to receptor-mediated clearance are a number of mechanisms by which the attachment of a PEG polymer to the backbone of a polypeptide may prove beneficial in enhancing the pharmacokinetic properties of the drug. Thus insulin to produce a less immunogenic product while retaining a substantial proportion of the biological activity.
PEG modification requires activation of the PEG polymer that is accomplished by the introduction of an electrophilic center. The PEG reagent is now susceptible to nucleophilic attack, predominantly by the nucleophilic epsilon-amino group of a lysyl residue. Because of the number of surface lysines present in most proteins, the PEGylation process can result in random attachments leading to mixtures which are difficult to purify and which may not be desirable for pharmaceutical use.
There are a large variety of PEG reagents that have been developed for the modification of proteins. This involves the covalent attachment of a PEG molecule via the formation of a linking group between the PEG polymer and the protein (see for example Zalipsky, et al., and Harris et. al., in: Poly(ethylene glycol) Chemistry: Biotechnical and Biomedical Applications; (J. M. Harris ed.) Plenum Press: New York, 1992; Chap.21 and 22). Some of these reagents are, to various degrees, unstable in the aqueous medium in which the PEGylation reaction occurs. In addition, the conjugation process often results in the loss of in vitro biological activity that is due to several factors foremost of which being a steric interaction with the proteins active sites. A desired property therefore of a new reagent would be one that is not susceptible to degradation in an aqueous medium and one that may be employed to affect the site specific modification of a protein. A PEG aldehyde may be considered such a reagent. For site specific N-terminal pegylation see Pepinsky et al., (2001) JPET,297,1059 (Interferon-β-1a) and U.S. Pat. No. 5,824,784(1998) to Kinstler et al., (G-CSF). The use of a PEG-aldehyde for the reductive amination of a protein utilizing other available nucleophilic amino groups, is described in U.S. Pat. No. 4,002,531(1977) to Royer, in EP O 154 316, by Wieder et al., (1979) J.Biol.Chem. 254,12579, and Chamow et al., (1994) Bioconjugate Chem. 5, 133.
SUMMARY OF INVENTION
In accordance with this invention, it has been discovered that aldehydes of the formula:
IA
wherein R is hydrogen or lower alkyl, X and Y are individually selected from —O— or —NH— with the proviso that X is NH when m is 1 and Y is —O—, PAG is a divalent residue of polyalkylene glycol resulting from removal of the terminal hydroxy groups, having a molecular weight of from 1,000 to 100,000 Daltons, z is an integer of from 2 to 4, m is an integer of from 0 to 1, and w is an integer of from 2 to 8.
IB
wherein A is a polyethylene glycol residue with its two terminal hydroxy groups being removed having a molecular weight of from 1,000 to 100,000 Daltons and having a valence of from 1 to 5, n is an integer of from 1 to 5 which integer is the same as the valence of A, R and w are as above.
IC
wherein PAG 1 and PAG 2 are independently divalent residues of poly lower alkylene glycol resulting from removal of the two terminal hydroxy groups with the PAG 1 and PAG 2 residues having a combined molecular weight of from 1,000 to 100,000 Daltons, R and R 1 are individually lower alkyl or hydrogen, p is an integer of from 1 to 5, and z and w are as above.
are useful for conjugation to therapeutically active proteins to produce PAG protein conjugates which retain a substantial portion of their therapeutic activity and are less immunogenic than the protein from which the conjugate is derived.
In accordance with this invention, a new synthesis has been found for the aldehyde of formula:
ID
RO-PAG-O(CH 2 ) z —O—(CH 2 ) w —CHO
wherein R, PAG, z and w are as above.
which like the compounds of formula IA, IB and IC, is a reagent for producing PAG protein conjugates.
DETAILED DESCRIPTION
The aldehyde reagents of formula IA, IB, IC and ID can be conjugated to therapeutically active proteins to produce therapeutically active protein conjugates which retain a substantial portion of the biological activity of the protein from which they are derived. In addition, the reagents of this invention are not susceptible to degradation in the aqueous medium in which the pegylation reaction is carried out. Furthermore, the aldehyde reagents of this invention can be conjugated to the protein in a controlled manner at the N-terminus. In this way, these aldehydes produce the desired conjugates and avoid random attachment leading to mixtures that are difficult to purify and which may not be desirable for pharmaceutical use. This is extremely advantageous since not only are the purification procedures expensive and time consuming but they may cause the protein to be denatured and thus bring about an irreversible change in the proteins tertiary structure.
The therapeutic proteins which can be conjugated in accordance with this invention can be any of the conventional therapeutic proteins. Among the preferred proteins are included interferon-alpha, interferon-beta, consensus interferon, G-CSF, GM-CSF, EPO, hemoglobin, interleukins, colony stimulating factor, as well as immunoglobulins such as IgG, IgE, IgM, IgA, IgD and fragments thereof.
The term polyalkylene glycol designates poly(lower alkylene)glycol radicals where the alkylene radical is a straight or branched chain radical containing from 2 to 7 carbon atoms. The term “lower alkylene” designates a straight or branched chain divalent alkylene radical containing from 2 to 7 carbon atoms such as polyethylene, polypropylene, poly n-butylene, and polyisobutylene as well as polyalkylene glycols formed from mixed alkylene glycols such as polymers containing a mixture of polyethylene and polypropylene radicals and polymers containing a mixture of polyisopropylene, polyethylene and polyisobutylene radicals. The branched chain alkylene glycol radicals provide the lower alkyl groups in the polymer chain of from 2 to 4 carbon atoms depending on the number of carbon atoms contained in the straight chain of the alkylene group so that the total number of carbons atoms of any alkylene moiety which makes up the polyalkylene glycol substituent is from 2 to 7. The term “lower alkyl” includes lower alkyl groups containing from 1 to 7 carbon atoms, preferably from 1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, etc. with methyl being especially preferred.
In accordance with a preferred embodiment of this invention, PAG in the compound in formulas IA, IC and ID is a polyethylene glycol residue formed by removal of the two terminal hydroxy groups. Further in accordance with this invention, PAG in the compound of formula IA, IC and ID, and the A in the compound of formula IB, have molecular weights of from about 10,000 to 50,000 most preferably from about 20,000 to about 40,000. In the compound of formula IC it is generally preferred that the radicals PAG 1 and PAG 2 have a combined molecular weight of from about 10,000 to 50,000 and most preferably from about 20,000 to 40,000. In the compound of formula IC it is generally preferred that p be an integer of from 1 to 5.
The aldehydes of compounds of formula IA, IB, IC and ID are used in forming polyalkyleneoxy protein conjugates. The aldehydes of this invention are intermediates for conjugation with the terminal amino group as well as other free amino groups on the protein to produce a therapeutically effective conjugate that has the therapeutic properties of the native protein. These conjugates when compared to the proteins from which they are derived, show a reduced rate of clearance, decreased antigenicity, diminished in vivo proteolysis, increased water solubility, reduced renal clearance, and less susceptibility to receptor-mediated clearance. All of these factors can help make the conjugate a more effective therapeutic agent than the unmodified protein itself. The aldehydes of this invention are converted to their protein conjugates in accordance with the following reaction scheme:
wherein PNH 2 is a protein covalently attached to a PEG via a nucleophilic amino group of the protein.
In this reaction scheme, G-CHO in the compound of formula V is a composite of the compounds of IA, IB, IC and ID showing the reactive aldehyde group. In the compound of formula IB, the number of aldehyde groups are in accordance with the valence “n”. If “n” were 4, the reaction in this scheme will take place at four different sites in this compound of formula V. In this reaction scheme, P is the protein containing a nucleophilic —NH 2 group that is conjugated with the compounds of formula IA, IB, IC and ID.
As is illustrated in the above reaction scheme, there is an equilibrium that is established between the aldehyde V and its conventional hydrate IV. This equilibrium is pH dependent, and consequently the concentrations found for the aldehyde V and its hydrate IV, will depend largely on the particular acidity of the solution. The polyalkylene aldehyde of formula V, is reacted with the amine of the protein to form the imine linkage of formula VI. This imine linkage of the compound of formula VI is then reduced to an amine through the use of reducing agents such as cyanoborohydride to give the saturated conjugated protein of formula VII. The reaction whereby aldehydes are conjugated with proteins through reductive amination is set forth in U.S. Pat. No. 4,002,531, EPO 154,316 and U.S. Pat. No. 5,824,784.
In reacting the compound of formula V with P—NH 2 , one can control this reaction so that the aldehydes of formula IA, IB, IC and ID only react at a single site located at the N-terminus amine on the protein. This can be done by carrying out the reaction of the compound of formula V with P—NH 2 at a pH of from 5.5 to 7.5. In carrying out this reaction, various buffers which maintain the reaction media at a pH of from 5.5 to 7.5 can be used. If one wants the amination to proceed on more than one amino site on the protein, then one carries out the reaction at a pH of 8.0 and above, preferably at a pH of from 8 to 10. In this manner, amino groups, as well as, the N-terminal amino group on the protein are aminated with the PAG aldehydes of this invention.
The specific PEGylating reagents of formula IA, IB, IC and ID of this invention, are stable in aqueous medium and not subject to aldol decompositions under the conditions of the reductive amination reaction. The amino groups on proteins such as those on the lysine residues are the predominate nucleophilic centers for the condensation of the aldehydes of this invention. However by controlling the pH of the reaction one can produce a site specific introduction of a polyalkylene glycol polymer on the protein at the desired N-terminus amino acid. When the compounds of formula IA are conjugated to a protein as is shown in Scheme 1, the resulting compound is:
wherein R, P, Y, PAG, X, m, w and z are as above.
When the compound in formula IB is conjugated to a protein as is shown in Scheme 1, the resulting compound is:
wherein A,P, n and w are as above.
When the compound of formula IC is conjugated to a protein as is shown in Scheme 1, the resulting compound is:
wherein R, R 1 , P, PAG 1 , PAG 2 , p, w and z are as above.
When the compound of formula ID is conjugated with the protein as is shown in Scheme 1 the resulting compound is:
RO-PAG-O—(CH 2 ) z —O(CH 2 ) w CH 2 NHP III-D
wherein R, PAG, P, z and w are as above.
In accordance with this invention, in formula I A, when m is 0 and X is —NH—, these compounds have the formula:
wherein R, PAG, z and w are as above.
The compound of formula I-Ai can be prepared by the following reaction scheme:
wherein R, PAG, z and w are as above, R 2 is lower alkyl, and OL is a leaving group.
In the first step of the reaction to produce the compound of formula I-Ai, the acid group of the compound in formula VIII is activated to produce the compound of formula IX. This is accomplished by activating the acid group on the compound of formula VIII with an activating agent to produce a leaving group such as an N-hydroxy succinimide group. Any conventional method of converting a carboxy group into an activating leaving group such as an N-hydroxy succinimide group can be utilized to produce the compound of formula IX. In the next step of the synthesis, the compound of formula IX containing the activating leaving group is reacted with the amine acetal compound of formula X to produce the compound of formula XI. This reaction to form the amide of formula XI is carried out by any conventional means of condensing an amine with an activated carboxylic acid group. The compound of formula XI has the aldehyde protected as its acetal, preferably a lower alkyl acetal. Any conventional aldehyde protecting groups such as other alkyl acetals can also be utilized. The acetal of formula XI can be hydrolyzed to form the corresponding aldehyde of formula I-Ai. Any conventional means of hydrolyzing an acetal to form the corresponding aldehyde can be utilized to convert the compound of formula XI into the corresponding aldehyde of formula I-Ai.
In accordance with an other embodiment of preparing a compound of the formula I-Ai, the acetal of formula X is replaced with a dioxolane of the formula Xa that is reacted with compound IX to produce the intermediate of XIa. Compound XIa is then hydrolyzed to the corresponding vicinal diol and then oxidized with periodate to produce the aldehyde of formula I-Ai.
wherein R, PAG, z and w are as above, OL is a leaving group, and R 13 is hydrogen, alkyl, or phenyl.
In the compound of formula IA where m is 1, X is —NH— and Y is —O—, this compound has the formula:
wherein R, PAG, z and w are as above.
The compound of formula I-Aii can be prepared by the following reaction scheme.
wherein OL, R, R 2 , PAG, z and w are as above.
In the above reaction scheme the compound of formula XII is first reacted with a compound of formula XIII which is a halo formate containing a leaving group. Any conventional leaving group can be utilized as OL such as the leaving groups herein before mentioned. The preferred leaving group is a para-nitro phenol radical. One can utilize any of the conventional conditions for reacting an alcohol such as the compound of formula XII with a chloro formate such as the compound of formula XIII to produce the carbonate of formula XIV. The carbonate is then reacted with the amine of formula X to produce the compound of formula XV. This reaction is carried out as described hereinbefore with regard to reacting the compound of formula IX with the compound of formula X. The compound of formula XV is then hydrolyzed to produce the compound of formula I-Aii in the conventional manner as described in connection with the hydrolysis of the compound of formula XI hereinbefore.
In the same manner described in the alternate synthesis of I-Ai, the compound of formula Xa is reacted with the carbonate XIV to produce the compound of formula XVa which is then hydrolyzed and oxidized to give the aldehyde I-Aii.
I-Aii
wherein R, PAG, z and w are as above, OL is a leaving group, and R 13 is hydrogen, alkyl, or phenyl.
In accordance with another embodiment of this invention wherein the compound of formula IA, m is 1 and Y and X are both —NH—, this compound has the formula
wherein R, PAG, z and w are as above.
The compound of formula I-Aiii can be produced by the following reaction scheme.
wherein R, PAG, z and w are as above and R 2 is lower alkyl.
In accordance with this embodiment, the compound of formula XVI is condensed with the compound of formula XVII in a halogenated hydrocarbon solvent to produce the compound of formula XVIII. This reaction utilizes conventional condensing procedures commonly used in reactions between an activated carbonate and an amine. The compound of formula XVIII is condensed with the amine of formula X in an inert organic solvent to produce the acetal of formula XIX. Any conventional inert organic solvent can be used in this reaction. The acetal of formula XIX is then hydrolyzed in acidic medium, in the manner described hereinabove to produce the compound of formula I-Aiii.
In the same manner described in the alternate synthesis of I-Ai, the compound of formula Xa is reacted with the carbamate XVIII to produce the compound of formula XIXa which is then hydrolyzed and oxidized to give the aldehyde I-Aiii.
I-Aiii
wherein R, PAG, z and w are as above, OL is a leaving group, and R 13 is hydrogen, alkyl, or phenyl.
The preparation of the compounds of the type Xa where R 13 is hydrogen has been described for w=2 (Petrov et al., Zh. Obshch. Khim. 1962, 32, 3720), w=3 (Olsen et al., J. Org. Chem. 1985, 50, 896) and w=4 (Timofeev et al., Nucleic Acids Res. 1996, 24, 3142).
In the compound of formula IA where m is 1, Y is —NH— and X is —O— the compound has the following formula:
RO-PAG-O(CH 2 ) z —NHCOO(CH 2 ) w CHO I-Aiv
wherein R, PAG, z and w are as above.
The compound of formula I-Aiv is prepared by means of the following reaction scheme:
wherein R,R 13 , PAG, z and w are as above.
In this reaction, the starting material of formula XX is a tri-hydroxy compound having a terminal primary hydroxy group which is separated by at least two carbon atoms from two other hydroxy groups that are vicinal to each other. The compound of formula XX is converted to its acetonide derivative of formula XXI by reacting the two vicinal hydroxy groups with acetone leaving free the third hydroxy group. Any conventional method of forming an acetonide derivative from the two vicinal hydroxy groups can be utilized to carry out this reaction to form the compound of formula XXI. Reagents other than acetone, which are known to form cyclic acetals with 1,2-diols, may also be used. The free hydroxy group in the acetonide derivative of formula XXI is then activated with an activating group such as the p-nitro phenyl chloro formate as is shown in the reaction scheme. This reaction to convert the hydroxy group into an activated derivative is well known in the art. In this manner the compound of formula XXII is produced where the primary hydroxy group on the compound of formula XXI is activated. The compound of formula XXII is then condensed with the PEG amine of formula XVI to form the condensation product of formula XXIII. Any conditions conventional in reacting an activated alcohol with an amine to produce a urethane can be utilized to carry out this condensation. The compound of formula XXIII containing the acetonide is then cleaved utilizing conditions conventional in cleaving acetonides such as by treatment with a mild acid, to produce the corresponding di-hydroxy compound. The resulting dihydroxy groups are then oxidized with mild oxidizing agents such as a periodate oxidizing agent to produce the aldehyde of formula I-Aiv. Any conventional method of oxidizing a vicinal di-hydroxy compound to the corresponding aldehyde can be utilized to carry out this conversion.
The compound of formula IB is synthesized from RO-PEG-OR by reaction with acrylic acid by the following reaction scheme:
wherein A, R, w, n and R 2 are as above.
The acrylic acid of formula XXV can be reacted with the polyethylene glycol polymer of formula XXIV in the manner disclosed in U.S. Pat. No. 4,528,334 to Knopf, et al., to produce the compound of formula XXVI. The addition of acrylic acid across the various polyethylene glycol units in the series of polyethylene glycol residues designated A can be controlled so that from 1 to 5 bonds with the acrylic acid will take place to form the acrylic acid graft copolymer of formula XXVI. In this manner depending upon the conditions used, as disclosed in U.S. Pat. No. 4,528,334, from 1 to 5 additions of acrylic acid will occur in the polyethyleneoxy chain. In accordance with this invention, an activated form of the carboxy group of the graft copolymer of formula XXVI is reacted with the compound of formula X to form the compound of formula XXVII via amide formation. This reaction is carried out in the same manner as described hereinbefore in connection with the conversion of the compound of formula VIII to the compound of formula XI by reaction of the compound of formula X, through the use of an appropriate carboxy activating leaving group as in formula IX. By the procedure described in connection with the conversion of the acetal of XI to the aldehyde of formula I-Ai, the acetal of formula XXVII was converted to the derivative IB.
The compound of formula IC can be prepared as shown by the following reaction scheme:
wherein R, R 2 , R 1 , PAG 1 , PAG 2 , OL, p, w and z are as above.
The derivative of formula IC is prepared from a compound of formula XXVIII in which there is an activated carboxyl group. This carboxyl group can be activated in the manner disclosed hereinbefore with respect to the activation of the compound of the formula VIII to produce the compound of the formula IX. The activated compound is then condensed with the amino acetal compound of formula X to produce the compound of formula XXIX in the same manner as described hereinbefore in connection with the reaction of the compound of formula IX with the compound of formula X to produce the compound of formula XI. The compound of formula XXIX is next converted to the compound of the formula IC by acid hydrolysis as described herein before in connection with the preparation of the compound of formula I-Ai from compound XI.
In the same manner described in the alternate synthesis of I-Ai, the compound of formula Xa is reacted with the derivative XXVIII to produce the compound of formula XXIXa which is then hydrolyzed and oxidized to give the aldehyde IC.
wherein R, R 1 , PAG 1 , PAG 2 , R 13 , OL, p, w and z are as above.
The compound of formula ID is produced from a compound of the formula XII via the following reaction scheme:
wherein R,R 13 ,PAG, and w and z are as above, X may be a halogen or sulfonate ester and B is an alkalai metal.
In carrying out this process the compound of formula XII is converted to the compound of formula XXX by converting the hydroxy group on the compound of formula XII to an activating leaving group. The conversion of the terminal hydroxyl group of compound XII into an activated halide leaving group X, can be readily achieved by reaction with a conventional halogenating reagent such as thionyl bromide. On the other hand where leaving groups, other than halides, are utilized, the hydroxy group of the compound of formula XII may be converted to a sulfonate ester by reaction with a halide of the activating leaving group such as mesyl or tosyl chloride. Any conventional method for converting the hydroxy group of compound XII to an activating leaving group such as a tosylate or mesylate or any of the aforementioned leaving groups can be utilized to produce the compound of formula XXX. This reaction may be carried out by reacting the formula XII with a halide of an activating leaving group such as tosyl chloride. The compound of formula XXX can then be condensed with the alkoxide of formula XXIa to form the compound of formula XXXI. In this case the acetonide group is a precursor to the aldehyde of formula ID. In the case shown in the above reaction scheme where an acetonide is used, the acetonide can be hydrolyzed in mild acid. However any conventional means to produce the resulting dihydroxy compound from an acetonide can be used in this conversion. The dihydroxy compound resulting form this hydrolysis can then be oxidized with a periodate to give the aldehyde of formula ID. This aldehyde can be reacted as set forth in Scheme 1 with a protein at the N-terminal amino acid to form the conjugate of the compound of formula IIID as described hereinbefore.
The compound of formula ID can also be produced from a compound of the formula XXI via the following reaction scheme.
wherein R, R 13 , and w are as above, PEG is a divalent residue of polyethylene glycol resulting from removal of the terminal hydroxy groups, having a molecular weight of from 1,000 to 100,000 Daltons.
In this reaction process, the compound of formula XXI is reacted with any conventional organic alkali metal base such as potassium naphthalide to form the corresponding alkoxide XXIa. Liquid ethylene oxide is then added under conventional polymeric conditions to a solution of XXIa. In this manner the anionic ring opening and polymerization of ethylene oxide is allowed to proceed under conditions that are well known for the production of polyethylene glycol polymers. In addition the amount of polymerization of the ethylene oxide can be controlled by conventional means to produce a polyethylene polymer of any desired molecular weight. Any remaining ethylene oxide is then removed from the reaction mixture. Reaction for several hours, with an excess of an alkyl halide such as methyl iodide, results in the formation of a terminal alkyl ether. The product, the compound of formula XXXII, may then be converted to a compound of the formula ID in the same manner as described hereinbefore for the conversion of the compound of formula XXXI to the compound of formula ID. The compounds of formula ID and their intermediates, are considered as new derivatives when w is an integer from 3 to 8.
The aldehydes of formula IA, IB, IC and ID can be conjugated as described herein before with various proteins through an amine group on the protein by the process of reductive amination as disclosed in U.S. Pat. No. 5,824,784 dated Oct. 20, 1998. By means of regulating the pH (i.e. from 5.5 to 7.5) the aldehydes in this invention may condense at the N-terminus amino group of a protein so as to obtain a monoconjugate derivative. In this manner, the pegylating reagents of IA, IB, IC and ID can from site specific mono-conjugates with the N-terminal amino group of various proteins thereby avoiding the necessity of employing extensive purification or separation techniques. On the other hand, if higher pH's from about 8.5 and above are utilized, the reductive amination procedure will also involve the various lysine amino groups which are available in the protein molecule. Among the preferred proteins for such conjugations are included G-CSF, GM-CSF, interferon-α, interferon-β, EPO and Hemoglobin.
In accordance with this invention, when the embodiments of formula I-Ai, I-Aii, I-Aiii and I-Aiv are reacted with the proteins by reaction as shown in Scheme 1, the following compounds are produced.
wherein P, R, PAG, z and w are as above.
The following examples are illustrative of the invention and are not to be construed as limiting the invention. In the following examples, the numbering as “1,” etc. refers to the reaction scheme following the descriptive portions in each example.
EXAMPLES
Example 1
Scheme A (Type I-Ai)
Synthesis of mPEG-amide-propionaldchyde.
Methoxy PEG-OH (M.W. 20,000, n=452) 1 and potassium t-butoxide were dissolved in t-butyl alcohol and stirred at 60° C. Ethyl bromoacetate was then slowly added and the mixture stirred for another 15 hours at 80-85° C. After filtering the reaction mixture, the solvent was evaporated under reduced pressure. The residue was dissolved in distilled water, washed with diethyl ether, and extracted twice with dichloromethane. The dichloromethane solution was dried over magnesium sulfate and the solvent removed under vacuum. Precipitation was induced by the addition of diethyl ether to the crude residue and the precipitated compound was then filtered and dried under vacuum to give the product 2 as a white powder.
The mPEG-ethyl acetate was dissolved in 1 N-sodium hydroxide and stirred for 15 hours at room temperature. The reaction mixture was then adjusted to pH 2 with 1 N aqueous HCl and extracted twice with dichloromethane. The extracted organic layer was dried over magnesium sulfate and the organic solvent removed. Diethyl ether was then added to the residue and the precipitated compound filtered. The product was dried under vacuum and the resulting acid 3 obtained as a white powder.
To a solution of the mPEG-acetic acid 3 dissolved in dichloromethane and cooled to 0-5° C., was added N-hydroxysuccinimide followed by a solution of dicyclohexylcarbodimide in dichloromethane. The reaction mixture was stirred for 15 hours at room temperature. The by-product, dicyclohexylurea, was removed from the reaction mixture by filtration and the residual organic solvent evaporated. The crude residue was then recrystallized from ethyl acetate filtered, washed twice with diethyl ether and dried for 12 hours under vacuum to afford the mPEG-succinimidyl acetate 4 as a white powder (see Example 2).
The mPEG-succinimidyl acetate 4 was dissolved in dichloromethane and stirred at room temperature while a solution of 1-amino-3,3-diethoxypropane in dichloromethane was added. The resulting solution was then stirred for 2 hours at room temperature. Precipitation was induced by the addition of diethyl ether. The product was then filtered and recrystalized from ethyl acetate. The recrystalized compound was dried under vacuum to give 5 as a white powder.
The diethyl acetal 5 was dissolved in an aqueous solution containing phosphoric acid (pH1) and stirred for 2 hours at 40-50° C. After cooling the reaction mixture to room temperature, the acidity was reduced to a pH6 by the addition of a 5% aqueous sodium bicarbonate solution. Brine was added and the resulting mixture extracted twice with dichloromethane. The organic layer was dried over magnesium sulfate, filtered and the solvent evaporated under reduced pressure. Precipitation was induced by the addition of diethyl ether to the crude residue. The product was collected and dried under vacuum to give 6 as a white powder.
By using the same procedure, compounds of the type I-Ai can be prepared whereby the integer n may be from 22 to 2,300.
The integer n may be from 22 to 2,300 but more preferably 22 to 1,000.
Example 2
Scheme B (Type I-Ai)
Synthesis of mPEG-amide-butyraldehyde
To 10 g, (1 mmol) of polyethylene glycol propionic acid 1, (MW 10,000, n=226) dissolved in dry methylene chloride (30 ml) was added dry and finely powdered NHS (0.56 g, 5 mmol). The flask was cooled in an ice-water bath and DCC (0.22 g, 1.08 mmol) added. The reaction mixture was stirred at 0° C. for 1 h and at room temperature for 24 h. The precipitated 1,3-dicyclohexylurea (DCU) was removed by filtration, and the filtrate added to ether (50 ml). After cooling to 4° C. the crude material 2 was collected by filtration and purified by precipitating twice from methylene chloride by the addition of ether.
To the N-hydroxy succinate derivative 2 (8.5 g˜0.85 mmol) dissolved in dry methylene chloride (25 ml) there was added 1-amino-4,4-dimethoxybutane (0.33 g, 2.5 mmol). The reaction mixture was stirred at room temperature for 2 h and the product precipitated in ether (100 ml). After cooling to 4° C., the crude acetal of formula 3 was collected by filtration and then re-dissolved in a minimum of methylene chloride. The product was then precipitated by the addition of ether to give 8 g of the acetal as a white solid. The acetal was then dissolved in 50 ml of 0.1M HCL and stirred at room temperature for 4 h to produce the amide aldehyde 4. The water was then removed under reduced pressure, and the crude amide-aldehyde product 4 purified by chromatography. By using the same procedure, compounds of the type I-Ai can be prepared whereby the integer n may be from 22 to 2,300.
The integer n may be from 22 to 2,300 but more preferably 22 to 1,000.
Example 3
Scheme C (Type I-Aii)
Synthesis of mPEG-urethane-propionaldchyde.
Triphosgene (148 mg, 0.5 mmol) in 5 ml of dichloromethane was added slowly to a solution of 10 g of mPEG 1 (0.5 mmol) (MW 20,000, n=452)) dissolved in 30 ml of dichloromethane and the resulting mixture stirred for 15 hours at room temperature. The organic solvent was then removed under vacuum and the residue washed with dry ether and filtered. The acid chloride was then dissolved in 30 ml of dry dichloromethane and treated with 80 mg (0.7 mmol) of N-hydroxysuccinimide followed by triethylamine (71 mg, 0.1 ml). After 3 hours, the solution was filtered and evaporated to dryness. The residue was dissolved in warm (50° C.) ethyl acetate, and then the solution cooled to 0° C. The resulting precipitate 2 was collected as a white powder, and the product dried under vacuum.
To a solution of the 5 g (0.25 mmol) of mPEG-succinimidylcarbonate 2 dissolved in 30 ml of dichloromethane was added 1-amino-3,3-diethoxypropane (110 mg, 0.75 mmol). The reaction mixture was then stirred for 2 hours at room temperature. Ether was then added and the resulting precipitate collected and recrystalized from ethyl acetate. The product was washed twice with diethylether and dried under vacuum to give 3 as a white powder.
The diethyl acetal 3 (5 g) was dissolved in an aqueous solution containing phosphoric acid (pH1) and stirred for 2 hours at 40-50° C. After cooling the reaction mixture to room temperature, the acidity was reduced to a pH6 by the addition of a 5% aqueous sodium bicarbonate solution. Brine was added and the resulting mixture extracted twice with dichloromethane. The organic layer was dried over magnesium sulfate, filtered and the solvent evaporated under reduced pressure. Precipitation was induced by the addition of diethyl ether to the crude residue. The product was collected and dried under vacuum to give 4 as a white powder.
By using the same procedure, compounds of the type I-Aii can be prepared whereby the integer n may be from 22 to 2,300.
The integer n may be from 22 to 2,300 but more preferably 22 to 1,000.
Example 4
Scheme D (Type I-Aii)
Synthesis of mPEG-urethane-butyraldehyde.
To a solution of 201.6 mg (1 mmol) of 4-nitrophenyl chloroformate and 118.6 mg (0.97 mmol) of 4-dimethylaminopyridine dissolved in 10 ml of dry methylene chloride was added dropwise a solution of 9.7 g (0.97 mmol) of mPEG 1 (MW 10,000, n=225) dissolved in 50 ml of methylene chloride. After stirring for 1 h at room temperature, 172.8 mg (1.17 mmol) of 1-amino-4,4-dimethoxybutane was then added to the solution of the 4-nitrophenyl carbonate derivative 2. Stirring was continued for 20 h after which time the product 3 was precipitated by the addition of ether (100 ml).
After cooling to 4° C., the crude acetal of formula 3 was collected by filtration and precipitated twice with ether from a methylene chloride solution to give 8 g of the acetal as a white solid. The acetal was then dissolved in 50 ml of 0.1M HCL and stirred at room temperature for 4 h. The water was then removed under reduced pressure, and the crude urethane-aldehyde 4 purified by chromatography.
By using the same procedure, compounds of the type I-Aii can be prepared whereby the integer n may be from 22 to 2,300.
The integer n may be from 22 to 2,300 but more preferably 22 to 1,000.
Example 5
Scheme E (Type I-Aiii)
Synthesis of mPEG-urea-propionaldchyde.
To a solution of 2 g (0.2 mmol) of alpha-(2-aminoethyl)-omega-methoxypoly(oxy-ethanediyl)(MW 10,000, n=226) of formula 1 in 40 ml of dry methylene chloride, was added at 0° C., 65 mg (0.3 mmol) of di-2-pyridyl carbonate 2 and the mixture stirred for 5 h. The product of formula 3 was then precipitated by the addition of 100 ml of ether, filtered, and washed with an additional 100 ml of ether. The product was then dried under vacuum under a slow stream of nitrogen to give 1.9 g of the compound of formula 3 as a white powder. To the resulting urethane intermediate (1.5 g˜1.5 mmol) dissolved in dry methylene chloride (25 ml) was added 0.6 g (˜4 mmol) of 1-amino-3,3-diethoxypropane. The reaction mixture was stirred at room temperature for 12 h and the acetal of formula 4 precipitated from ether (100 ml). After cooling to 4° C. the crude acetal was collected by filtration and precipitated twice from methylene chloride by addition of ether to obtain 1.1 g of the acetal as a white solid. The acetal was then dissolved in 50 ml of 0.1M HCL and stirred at room temperature for 4 h. The water was then removed under reduced pressure, and the crude urea-aldehyde product of formula 5 was purified by chromatography (the use of reagent 3 for urea formation, see U.S. Pat. No. 5,539,063).
By using the same procedure, compounds of the type I-Aiii can be prepared whereby the integer n may be from 22 to 2,300.
The integer n may be from 22 to 2,300 but more preferably 22 to 1,000.
Example 6
Scheme F (Type I-Aiv)
Synthesis of mPEG-urethane-butyraldehyde.
A mixture of pentane-1,2,5-triol 1 (11.7 g, 97.5 mmol) and toluene-p-sulfonic acid (0.3 g) in acetone-light petroleum ether (bp 40-60) (1:1 60 ml) was refluxed 24 h with a Dean-Stark apparatus. The solvent was then removed under vacuum and the residue dissolved in ether. The ethereal solution was washed with aqueous sodium carbonate, dried (Na 2 CO 3 ) and the ether removed. The resulting oil was then distilled to give 10.7 g of the 1,3-dioxolane-2,2-dimethyl-4-propanol of formula 2 bp. 117-118, 12 mm.(Golding et al., (1978) J. C. S. Perkin II, 839).
To a solution of 11.2 g (55 mmol) of 4-nitrophenyl chloroformate in 100 ml of acetonitrile was added slowly 7.3 g (60 mmol) of 4-dimethylaminopyridine followed by 8 g (50 mmol) of the above acetonide product 2 dissolved in 20 ml of acetonitrile. After stirring for 24 h, the precipitated pyridinium hydrochloride was filtered and the solvent removed under reduced pressure. The residue was then dissolved in 200 ml of ether and washed with a 5% aqueous solution of sodium bicarbonate. The ether solution was then dried (Na 2 CO 3 ) and the solvent removed under vacuum to give 16 g of the acetonide of formula 3.
To a solution of 6 g (0.6 mmol) of alpha-(2-aminoethyl)-omega-methoxypoly(oxy-ethanediyl) (MW 10,000,n=226) of formula 4 in 40 ml of dry methylene chloride, was added at 0° C., 196 mg (0.6 mmol) of the 4-nitrophenyl carbonate of formula 3 and 74 mg of 4-dimethylaminopyridine. The solution was stirred for 24 h after which time the compound of formula 5 was precipitated by the addition of 150 ml of ether. This product was filtered and further washed with ether to give 5 g of the urethane-acetonide of formula 5 as a white solid.
Compound 5 (5 g, 0.5 mmol) was then dissolved in 75 ml of 0.1M HCl and stirred for 6 h. The water and HCl were then removed under reduced pressure to give the corresponding diol product. To 5 g of the diol dissolved in 75 ml water was added 267 mg of NaIO 4 (1.25 mmol) and the reaction allowed to proceed for 5 h in the dark. The aldehyde of formula 6 was then isolated by size exclusion chromatography on a Sephadex G 10 column. Oxidation of the 1,2-diol may also be realized using NaIO 4 supported on wet silica gel. Using this procedure the aldehyde is obtained without hydrate formation. (see Vo-Quang et al., (1989) Synthesis No.1,64).
By using the same procedure, compounds of the type I-Aiv can be prepared whereby the integer n may be from 22 to 2,300
The integer n may be from 22 to 2,300 but more preferably 22 to 1,000.
Example 7
Scheme G (Type IB)
Synthesis of Pendant mPEG-urethane-propionaldehyde.
Nonane was added to a reaction vessel containing mPEG (M.W. 20,000), and heated to 140-145° C. When the solid melted, acrylic acid and t-butyl peroxybenzoate (a reaction initiator) were slowly added to the reaction mixture over a period of 1.5 hours. After the addition, the mixture was stirred for an additional hour at 140-145° C. After the removal of residual nonane from the reaction mixture by evaporation, methanol was added to the mixture and heated and stirred until a homogeneous solution was obtained. The hot solution was then filtered under vacuum and the filtrate diluted with a 90/10/, v/v, MeOH/H 2 O solution. The resulting mixture was then filtered through a Pall Filtron ultrafiltration system and the filtrate then concentrated under reduced pressure. The residue was dissolved by heating with a 50/50, v/v, acetone/isopropyl alcohol solution, cooled to room temperature, and placed in the refrigerator overnight. The product 1 was then filtered, washed 3 times with 50/50, v/v, acetone/isopropyl alcohol solution and finally 3 times with diethyl ether and then vacuum dried overnight. The acid number of the pendant-PEG-propionic acid 1 was determined by titration (mg of KOH needed to neutralize one gram of sample).
The pendant-PEG-propionic acid 1 was dissolved in dichloromethane and cooled to 0-5° C. N-hydroxysuccinimide was then added followed by the addition of dicyclohexylcarbodimide dissolved in chloromethane. After stirring for 15 hours at room temperature, the dicyclohexylurea by product was removed from the reaction mixture by filtration and the residual organic solvent evaporated under vacuum (see Example 2). The crude residue was recrystalized from ethyl acetate, filtered, washed twice with diethyl ether, and dried for 12 hours under vacuum to give the pendant PEG-succinimidyl propionate 2 as a white powder.
To a solution of the pendant PEG-succinimidyl propionate 2 dissolved in dichloromethane was added at room temperature 1-amino-3,3-diethoxypropane and the resulting solution stirred for 2 hours. Precipitation was induced by the addition of diethyl ether and the product so obtained recrystalized from ethyl acetate. The recrystalized compound was filtered, washed twice with diethyl ether, and dried for 12 hours under vacuum to give the pendant-PEG-propoionaldehyde diethylacetal 3 as a white powder.
The pendant-PEG-propionaldehyde diethyl acetal 3 was dissolved in an aqueous solution containing phosphoric acid (pH 1) and stirred for 2 hours at 40-50° C. After cooling the reaction mixture to room temperature, the acidity was reduced to a pH6 by the addition of a 5% aqueous sodium bicarbonate solution. Brine was added and the resulting mixture extracted twice with dichloromethane. The organic layer was dried over magnesium sulfate, filtered and the solvent evaporated under reduced pressure. Precipitation was induced by the addition of diethyl ether to the crude residue. The product was collected and dried under vacuum to give the pendant PEG-amide propionaldehye 4 as a white powder.
By using the same procedure, compounds of the type IB can be prepared whereby the integer m may be from 22 to 2,300
The integer m may be from 22 to 2,300 but more preferably 22 to 1,000. The integer n may be 1 to 20 and more preferably 1 to 5.
Example 8
Scheme H (Type IC)
Synthesis of Branched mPEG-amide-propionaldehyde.
The conversion of the branched chain carboxy acid 1 to the corresponding propionaldehyde 2 was carried out in the same manner as described in Example 2.
wherein R, R 1 , PAG 1 , PAG 2 , p and z are as above.
Example 9
Scheme I (Type IC)
Synthesis of Branched mPEG-amide-butyraldehyde.
The conversion of the branched chain carboxy acid 1 to the corresponding butyraldehyde 2 was carried out in the same manner as described in Example 2.
wherein R, R 1 , PAG 1 , PAG 2 , p and z are as above.
Example 10
Scheme J (Type ID)
Synthesis of mPEG-Butyraldehyde.
A mixture of pentane-1,2,5-triol of formula 1 (11.7 g, 97.5 mmol) and toluene-p-sulfonic acid (0.3 g) in acetone-light petroleum ether (bp 40-60) (1:1 60 ml) was refluxed 24 h with a Dean-Stark apparatus. The solvent was then removed under vacuum and the residue dissolved in ether. The ethereal solution was then washed with aqueous sodium carbonate, dried (Na 2 CO 3 ) and the ether removed. The resulting oil was then distilled to give 10.7 g of 1,3 dioxolane-2,2-dimethyl-4-propanol of formula 2 bp. 117-118, 12 mm.(Golding et al., (1978) J. C. S. Perkin II, 839).
To a solution of 6 g (0.6 mmol) of mPEG alcohol (MW 10,000, n=226) in 40 ml of dry methylene chloride, was added at −10° C., 182 mg (0.26 ml) of trimethylamine and toluene-p-sulfonyl chloride (381 mg, 2 mmol). The cooling was removed and the mixture stirred at room temperature for 18 h. The product was precipitated by the addition of 150 ml of ether, filtered and further washed with ether to give 5 g of the PEG tosylate 3 as a white solid.
A solution of 320 mg (2.0 mmol) of 1,3-dioxolane-2,2-dimethyl-4-propanol 2 dissolved in 10 ml of dry dioxane was added dropwise under nitrogen to a mixture of 100 mg of sodium hydride suspended in 5 ml of benzene. The mixture was then stirred for 30 min to give the sodium alkoxide salt of 2. To this solution was then added dropwise over a 20-min period, a solution of 4 g (0.4 mmol) of the PEG tosylate 3 dissolved in 30 ml of dioxane. The reaction mixture was then stirred for 24 h at 40° C. and then added dropwise to 150 ml of ether to precipitate the compound of formula 4 as a white solid. This material was then purified by chromatography on a small alumina column.
The PEG acetonide 4 (3.5 g) was dissolved in 40 ml of 0.1M HCl and stirred for 6 h. The water and HCl were then removed under reduced pressure to give the corresponding diol product. To 3 g of the 1,2-diol dissolved in 40 ml water (˜0.3 mmol of diol) was added 160 mg of NaIO 4 (0.75 mmol) and the reaction allowed to proceed for 5 h in the dark. The PEG butyraldehyde 5 was isolated by size exclusion chromatography on a Sephadex G 10 column.
By using the same procedure, compounds of the type ID can be prepared whereby the integer m may be from 22 to 2,300
The integer n may be from 22 to 2,300 but more preferably 22 to 1,000.
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The present invention provides novel monofunctional polyethylene glycol aldehydes for the pegylation of therapeutically active proteins. The pegylated protein conjugates that are produced, retain a substantial portion of their therapeutic activity and are less immunogenic than the protein from which the conjugate is derived. New syntheses for preparing such aldehydes are described.
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This application is a divisional of U.S. patent application Ser. No. 09/178,209, filed on Oct. 23, 1998, now U.S. Pat. No. 6,162,565, issued on Dec. 19, 2000.
TECHNICAL FIELD
The present invention relates to the manufacture of photomasks and phase-shift masks. In particular, the invention relates to methods for forming chrome photomasks and for forming phase-shift masks without producing chrome opaque defects.
BACKGROUND OF THE INVENTION
A conventional photomask comprises a patterned light-shielding film of opaque material, typically a metal such as chromium, on a transparent mask substrate, typically silica (quartz). In photomask manufacture, a photoresist is applied to the opaque-material side of a mask blank comprising a layer of the opaque material on a transparent mask substrate. The photoresist is patterned by an image-wise exposure and wet developed to produce a pattern of photoresist over the opaque layer. The mask blank containing the imaged photoresist is either wet or dry etched to remove the opaque material revealed by removal of the photoresist. When the photoresist is stripped after etching, a patterned layer of opaque material remains on the transparent substrate.
Typically, a positive-tone, novolac-type photoresist is exposed by a laser tool and developed with TMAH: a dilute solution of tetramethyl ammonium hydroxide. TMAH developer is a strong base. The exposed portions of the opaque layer are wet etched with a ceric salt, typically ceric ammonium nitrate in 10% nitric acid or a ceric salt in 10% perchloric acid. An acidic solution of a ceric salt is a strong oxidizing agent.
When a wet etch is used, it is common practice to perform both the develop step and wet etch step sequentially in the same process chamber of the process tool. These steps are typically carried out using a spray process in which the developer and wet etchant are sequentially sprayed onto a rotating mask substrate in a single process chamber. The usual sequence is: develop, rinse with deionized water, wet etch, rinse with deionized water, and dry.
The ceric ion is soluble in the acidic etch solution. Basic ceric salts precipitate in neutral solution or in the basic developer solution, however, and form small particles across the entire mask blank. Over time, a steady build up of yellow ceric hydroxide particles, orange ceric ammonium nitrate particles, and mixtures of these cerium-containing particles forms and deposits throughout the process chamber. The nozzles that spray the rinse water also become contaminated with cerium. The rinse water contains cerium in both soluble and insoluble forms.
If a dry etch is used in place of a wet etch, the mask blank containing the patterned photoresist is developed with TMAH, washed with deionized water, dried, and transferred to a reactive ion etch system for the dry etch of the chrome layer. Although the dry etch does not use a cerium etchant, the process tool used to develop the photoresist is typically contaminated with cerium from other processing. Consequently, the mask blank is contaminated with cerium-containing particles during development. These particles are not removed by the deionized water rinse; rather, they produce chromium opaque defects on the resulting photomask due to micro-masking by the cerium-containing particles during dry etch of the chromium layer.
Most process tool manufacturers recommend a once-a-month manual washdown of the process tool with concentrated hydrochloric acid to remove the cerium compounds from the process tool. In addition to causing downtime, manual washdown is time consuming and inconvenient. Concentrated hydrochloric acid is corrosive and the precipitated cerium compounds and hydrochloric acid can react to produce chlorine gas and nitrogen dioxide.
Thus, a need exists for methods for removing precipitated particles of ceric salts from mask blanks prior to wet or dry etching to form photomasks and for methods for removing cerium deposits from process tools.
SUMMARY OF THE INVENTION
To meet this and other needs, and in view of its purposes, the present invention provides a method for forming a photomask on a mask blank having a transparent substrate and a chrome layer. When a dry etch is used to etch the chrome layer, the method comprises, in order, the steps of:
a) applying photoresist to the chrome layer of the mask blank, the mask blank either (i) having the chrome layer on the transparent substrate, or (ii) comprising, in order, the chrome layer, a phase-shift mask layer, and the transparent substrate;
b) patterning the photoresist;
c) wet developing the photoresist and removing a portion of the photoresist, revealing a portion of the underlying chrome layer;
d) rinsing the mask blank with water;
e) rinsing the mask blank with dilute acid;
f) rinsing the mask blank with water;
g) drying the mask blank;
h) dry etching the chrome layer and removing the portion of the chrome layer revealed in step c); and
i) stripping the photoresist from the mask blank.
When a wet etch is used to etch the chrome layer, the method comprises, in order, the steps of:
a) applying photoresist to the chrome layer of the mask blank, the mask blank either (i) having the chrome layer on the transparent substrate, or (ii) comprising, in order, the chrome layer, a phase-shift mask layer, and the transparent substrate;
b) patterning the photoresist;
c) wet developing the photoresist and removing a portion of the photoresist, revealing a portion of the underlying chrome layer;
d) rinsing the mask blank with water;
e) wet etching the chrome layer with an acidic solution of a ceric salt and removing the portion of the chrome layer revealed in step c);
f) rinsing the mask blank with water;
g) rinsing the mask blank with dilute acid;
h) rinsing the mask blank with water; and
i) stripping the photoresist from the mask blank.
The dilute acid does not attack the transparent substrate, the chrome layer, the phase-shift mask layer, or the photoresist, and cerium salts are soluble in the dilute acid. The dilute acid is preferably nitric acid or perchloric acid, more preferably nitric acid. The transparent substrate is preferably silica.
This method decreases the number of defects per photomask as well as the mask-to-mask variation in the number of defects. In addition, the acid rinse does not affect the photoresist so it is unnecessary to modify or change any other part of the overall process. The acid spray also prevents or removes the buildup of cerium-containing deposits in the process tool. This advantage reduces the number of times that the process tool must be cleaned to remove the buildup of cerium-containing deposits.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the invention.
BRIEF DESCRIPTION OF THE DRAWING
The invention is best understood from the following detailed description when read in connection with the accompanying drawing. Included in the drawing are the following figures:
FIG. 1 is a block diagram showing the steps for producing a photomask using a first embodiment of the method of the present invention;
FIG. 2 is a block diagram showing the steps for producing a photomask using a second embodiment of the method of the present invention;
FIG. 3 is a block diagram showing the steps for producing a phase-shift mask using another embodiment of the method of the present invention; and
FIG. 4 is a block diagram showing the steps for producing a phase-shift mask using still another embodiment of the method of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Cerium-containing particles are thought to be formed by three different methods: (1) reaction of the basic TMAH developer with the acidic cerium wet etch to form a basic solution, causing cerium to precipitate out as cerium hydroxide; (2) dilution of the cerium wet etch with the deionized rinse water, causing cerium-containing precipitates to form; and (3) evaporation of the cerium wet etch from the chamber walls, leaving behind a powdery residue of cerium-containing precipitate. Although the present invention is not limited by any theory or mechanism, it is thought that the acid rinse reduces the number of defects on the photomask by: redissolving precipitated cerium particles on the mask blank; neutralizing any of the basic developer remaining on the surface of the mask blank, thus preventing formation of cerium-containing basic salt particles; and redissolving any cerium-containing particles present in the chamber, on the chamber walls, or on or in the nozzles or other structures.
A. Dry Etch of the Chrome Layer
FIG. 1 shows, in block diagram form, the steps of a first embodiment of the method of the present invention in which the chrome layer is etched by a dry etch. In step A, a conventional photoresist, such as a novolac-resin photoresist, is applied to a mask blank. The mask blank comprises an opaque material on a transparent mask substrate. The mask substrate is typically highly polished, optically flat silica (quartz, SiO 2 ) about 90 mil, (about 0.23 cm) to 250 mil (about 0.64 cm) thick. The layer of opaque material is typically a uniformly sputtered layer of chromium and chromium oxide about 1050 Å thick, typically referred to as the chrome layer. The photoresist is typically applied to the opaque layer by conventional spin coating. The layer of photoresist is typically 5000 Å thick. Throughout the specification, the term “mask blank” may be used to refer to this structure, even though some processing may have been carried out on the mask blank.
In step B, the photoresist is patterned, i.e., image-wise exposed to produce a pattern of exposed and unexposed photoresist on the mask blank. The photoresist is typically patterned by a conventional direct-write technique, such as electron beam (e-beam) exposure or laser exposure at the i-line wavelength (365 nm).
In step C, the mask blank containing the patterned photoresist is wet developed by a conventional technique. Development removes the regions of the photoresist exposed in step B, revealing the underlying opaque material. Novolac photoresists are typically developed with an aqueous solution of TMAH or an aqueous base, typically aqueous potassium hydroxide. Processing is typically carried out in a process tool, such as those manufactured by Fairchild or by Steag.
In step D, the mask blank containing the patterned and developed photoresist is rinsed with water. Distilled or deionized water is preferred for the water rinse. The mp ask blank is typically rinsed for about 3 minutes to about 5 minutes at about 20° C. to about 25° C.
In step E, the mask blank containing the patterned and developed photoresist is rinsed with an aqueous solution of a dilute acid. The acid rinse is typically carried out for about 3 minutes to about 5 minutes at about 20° C. to about 25° C.
The dilute acid should not attack the silica substrate, the chrome layer, or the photoresist. If the acid attacks the photoresist, the photoresist image formed during the patterning step will be changed, changing the chrome pattern on the photomask. Cerium salts, especially basic cerium salts, must be soluble in the dilute acid. The acid must dissolve cerium-containing particles and deposits present in the process tool and, once in solution, cerium salts must not precipitate out of the acid.
Preferred acids are nitric acid and perchloric acid. Both cerium containing 10% (volume-to-volume) nitric acid and cerium containing 10% perchloric acid are used to etch chrome layers to form photomasks. Nitric acid is more Preferred.
Nitric acid that is about 1-30% volume-to-volume, preferably about 5-20% volume-to-volume, most preferably about 10% volume-to-volume (equivalent to 7 wt % nitric acid), may be used for the acid rinse. If the nitric acid solution is too concentrated, the photoresist will be attacked.
In step F, the mask blank containing the patterned and developed photoresist is again rinsed with water. Distilled or deionized water is preferred for the water rinse. The mask blank is typically rinsed for about 3 minutes to about 5 minutes at about 20° C. to about 25° C.
In step G, the mask blank containing the patterned and developed photoresist is dried. Drying is typically carried out by an on-center, high-speed spin. In preparation for the dry etch, the mask blank is spun at high speed in the process tool.
In step H, the mask blank containing the patterned and developed photoresist is dry etched. Dry etching is typically carried out by a reactive plasma ion etch using a mixture of chlorine and oxygen in the plasma. During etching, the chrome layer is removed from those regions of the mask blank from which the photoresist was removed by the patterning and developing steps, revealing the underlying chrome layer. In regions in which photoresist was not removed, the photoresist protects the underlying chrome layer and prevents its removal. A mask blank containing a chrome layer that has been etched in the same pattern as the photoresist is formed.
In step I, the photoresist is stripped to produce the photomask. When photoresist is stripped, a patterned layer of chrome, which corresponds to the pattern formed in the photoresist, remains on the silica substrate, forming the photomask. Typically, the photoresist is stripped with a solution containing one volume of 30% hydrogen peroxide to three volumes of concentrated sulfuric acid. Stripping is typically carried out at about 85° C. to about 100° C. for about 7 minutes to about 10 minutes.
After the photoresist is stripped from the photomask, the photomask typically undergoes a conventional defect inspection, line-width and dimensional check, and final inspection.
B. Wet Etch of the Chrome Layer
FIG. 2 shows, in block diagram form, the steps of a second embodiment of the method of the present invention in which the chrome layer is etched by a wet etch. Steps A-D are described above. A mask blank with a patterned and developed photoresist is produced by steps A-D. Although the acid rinse described in step E is not required at this point, because ceric ion is soluble in the acidic etch solution, an acid rinse as described in step E may be carried out, if desired. If the acid rinse is carried out, a water rinse is not required, before wet etch, because the wet etch is carried out in acid solution. If desired, however, a water rinse as described in step F may be carried out.
In step J, the mask blank is wet etched with a ceric salt, typically ceric ammonium nitrate in 10% nitric acid or a cerium salt in 10% perchloric acid. Etching is typically carried out at about 20° C. to about 25° C. for about 1 minute to about 2 minutes. The wet etch removes the revealed portions of the chrome layer. A mask blank containing a chrome layer that has been etched in the same pattern as the photoresist is formed.
In step K, the mask blank containing the etched chrome layer and the patterned and developed photoresist is rinsed with water. The mask blank is typically rinsed for about 3 minutes to about 5 minutes at about 20° C. to about 25° C.
In step L, the mask blank is rinsed with a dilute aqueous acid as described in step E. With 10% nitric acid, the acid rinse is typically carried out for about 3 minutes to about 5 minutes at about 20° C. to about 25° C.
In step M, the mask blank is again rinsed with water as described above. The mask blank is typically dried following the final rise so that water is not added to the concentrated sulfuric acid used to strip the photoresist. Drying is typically carried out by an on-center, high-speed spin.
In step N, the photoresist is stripped from the mask blank containing the patterned chrome layer to form the photomask. The photoresist may be stripped as described in step I above.
C. Preparation of Phase-Shift Masks
In another embodiment, the invention is a method for preparing a phase-shift mask. The compositions of mask blanks used to form a phase-shift mask are well known to those skilled in the art. The mask blank comprises, in order, an opaque layer, typically a chrome layer; a phase-shift mask layer; and a transparent substrate, typically highly polished, optically flat silica (quartz, SiO 2 ) about 90 mil (about 0.23 cm) to 250 mil (about 0.64 cm) thick. The phase-shift mask layer comprises a metal compound, typically molybdenum silicide (MoSi).
FIG. 3 shows, in block diagram form, the steps of an alternate embodiment of the method of the present invention in which a phase-shift mask is formed. In this embodiment, the chrome layer is etched by a wet etch in step J. Steps A-D and J-N in this method are the same as described in FIG. 2, above, except that a mask blank containing a phase-shift layer between the chrome layer and the transparent substrate is used.
In step O, the mask blank containing the patterned and etched chrome layer is dry etched. Dry etching is typically carried out by a reactive plasma ion etch using a fluorine-containing compound such as carbon tetrafluoride or sulfur hexafluoride. During etching, the phase-shift mask layer is removed from those regions of the mask blank from which the chrome layer was removed by the patterning and developing steps, revealing the underlying phase-shift mask layer. In regions in which the chrome layer was not removed, the chrome layer protects the underlying phase-shift mask layer and prevents its removal.
In step P, a conventional photoresist is applied to the mask blank as in step A above. The photoresist is applied to the patterned and etched chrome layer. In step Q, the photoresist is patterned as in step B. In step R, the photoresist is wet developed as in step C. In step S, the photoresist is rinsed with water as in step D. Although the acid rinse described in step E is not required at this point, an acid rinse as described in step E may be carried out, if desired. If the acid rinse is carried out, a water rinse is not required before wet etch. If desired, however, a water rinse as described in step F may be carried out.
In step T, the chrome layer is wet etched, as in step J. In step U, the mask blank is rinsed with water as in step K. In step V, the mask blank is rinsed with acid as in step L. In step W, the mask blank is rinsed with water as in step M. If desired, the mask blank may be dried by an on-center, high-speed spin after step W and before step X. In step X, the photoresist is stripped from the mask blank, as in step N, to form the phase-shift mask.
FIG. 4 shows, in block diagram form, the steps of an alternate embodiment of the method of the present invention in which a phase-shift mask is formed. In this method, the chrome layer is etched by a dry etch in step H. Steps A-I in this method are the same as described in FIG. 1, above, except that a mask blank containing a phase-shift layer between the chrome layer and the transparent substrate is used. Steps O-X are the same as described in FIG. 3, above.
D. Prevention and Removal of Cerium-Containing Deposits
According to yet another embodiment of the present invention, a method is provided for reducing or preventing the buildup of cerium-containing particles and deposits in a process tool. The process tool comprises a chamber as well as a set of process nozzles and a set of chamber and bowl rinse nozzles. The process nozzles direct the spray at the sample being processed, which is attached to a spindle in the center of the chamber. The chamber and bowl rinse nozzles direct the spray at the chamber walls, rather than at the sample.
Process tool manufacturers recommend spraying concentrated hydrochloric acid through the chamber and bowl rinse nozzles about once a month to remove the cerium compounds from the process tool. Concentrated hydrochloric acid is corrosive and can attack the process tool. The precipitated cerium compounds and hydrochloric acid can react to produce chlorine gas and nitrogen dioxide.
A periodic acid spray through the chamber and bowl rinse nozzles prevents or removes the buildup of cerium-containing deposits in the process tool, reducing the number of times that the process tool must be cleaned. The dilute acid must not attack the process tool, and cerium salts must be soluble in the dilute acid. These acids are described in step E, above. The acid is typically sprayed for about 3 minutes to about 5 minutes at about 20° C. to about 25° C.
The acid spray is followed by a water rinse. Water is typically sprayed about 3 minutes to about 5 minutes at about 20° C. to about 25° C. Distilled or deionized water is preferred for the water rinse.
For best results in preventing the buildup of cerium-containing deposits, the periodic acid spray and water rinse should be completed at least once per day. If desired, the method may be conveniently carried out at the end of each shift, i.e, three times per day.
E. Industrial Applicability
The present invention is a method for forming photomasks that are used in the patterning of semiconductor wafers. Semiconductor wafers are used in the manufacture of various semiconductor devices, such as integrated circuits, which are used, for example, in digital computers. The advantageous properties of this invention can be observed by reference to the following example which illustrates, but does not limit, the invention.
EXAMPLE
Control Example
Bare chromium monitor plates (mask blanks without photoresist) were measured for initial particle levels using a KLA Starlight tool. The plates were run through a develop, deionized water rinse, and dry process sequence in a develop/wet etch process tool, and the particle level remeasured. All reagents were sprayed through the process nozzles in this process sequence. The process tool contained a high level of cerium-containing deposits and particles because it had been used for a considerable time to carry out conventional processing and had not been cleaned.
So many particles were found after processing that the KLA Starlight tool was saturated (>10,000 particles) and aborted the inspection. Subsequent characterization of the particles by energy dispersive X-ray analysis showed that most of the particles contained cerium.
Example 1
The procedure of the Control Example was repeated using bare chromium monitor plates, except that a process sequence consisting of develop, deionized water rinse, nitric acid rinse with 10% nitric acid, deionized water rinse, and dry was carried out. All reagents were sprayed through the process nozzles in this process sequence. Surface particle counts were taken before and after processing. Only 96 particles were added by the develop process.
Example 2
Mask blanks containing photoresist were patterned and developed (1) by the conventional process, and (2) by a process that included a nitric acid rinse and a water rinse after the wet development and water rinse steps. Scanning electron microscope (SEM) studies of the developed photoresists were carried out prior to the etch step. SEM showed no difference in the developed photoresist image size and no difference in the developed photoresist sidewall. No change in exposure conditions or development time was required to obtain nominal image size when development was followed by a nitric acid rinse and a water rinse.
Example 3
A process sequence consisting of: develop with TMAH, deionized water rinse, wet etch with ceric ammonium nitrate in 10% nitric acid, deionized water rinse, rinse with 10% nitric acid, deionized water rinse, and dry, was carried out for three weeks. 895I novolac photoresist (OCG Microelectronics) was used as the photoresist.
The hard opaque defect levels on the photomasks produced during this period were compared with the defect levels on the photomasks produced during the previous three weeks, in which the nitric acid rinse had been omitted. With the nitric acid rinse, the average number of hard opaque defects requiring repair per photomask was reduced by a factor of three and the one sigma of plate-to-plate variation in hard opaque defects was reduced by almost a factor of 10.
Although illustrated and described herein with reference to certain specific embodiments, the present invention is nevertheless not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the spirit of the invention.
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A method for removing contaminants from a substrate surface having a pattern formed on the surface. The method involves rinsing the substrate and pattern with water to remove acid reactive material. The substrate and pattern are then washed with an acid whose concentration is too low to attack the material that forms the pattern. Then the substrate is washed with water to remove the acid.
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BACKGROUND
1. Field of the Disclosure
The present disclosure relates to a method for obtaining human microglial precursor cells, comprising: (a) providing a cell population comprising neural precursor cells, wherein the cell population is obtainable from embryoid bodies differentiated from human pluripotent stem cells; (b) differentiating the cell population comprising neural precursor cells into microglial precursor cells by culturing in medium comprising a growth factor selected from the group consisting of insulin and insulin-like growth factors; (c) expanding and enriching microglial precursor cells in medium comprising a growth factor selected from the group consisting of insulin and insulin-like growth factors and 10 to 150 ng/ml GM-CSF; and (d) isolating microglial precursor cells comprising CD45-positive cells.
2. Discussion of the Background Art
In this specification, a number of documents including patent applications and manufacturer's manuals is cited. The disclosure of these documents, while not considered relevant for the patentability of this disclosure, is herewith incorporated by reference in its entirety. More specifically, all referenced documents are incorporated by reference to the same extent as if each individual document was specifically and individually indicated to be incorporated by reference.
Microglia are the resident immune cells of the central nervous system (CNS) and constitute about 10 to 20% of all glial cells in the adult CNS (Banati, 2003; Vaughan and Peters, 1974). The origin of microglia is still unclear. It was suggested that microglia appear in two waves, firstly in the neuroepithelium with unknown origin (Chan et al., 2007) and secondly in the brain during fetal development derived from the hematopoietic system and of mesodermal origin (Block and Hong, 2007; Chan et al., 2007).
Microglia respond to damage signals coming from injured tissue by undergoing activation of immune defence programs and proliferation (Ransohoff and Perry, 2009). Thus, microglia are responsible for the first line of the innate immune response in the CNS (Biber et al., 2007; Block et al., 2007; Hanisch and Kettenmann, 2007). Microglia are believed to remain in a resting stage under healthy physiological conditions. This stage is characterized by a ramified morphology and low expression of immunological molecules. In order to perform their surveillance function, microglia are highly dynamic during the resting stage and screen their environment. It is estimated that microglia can scan the entire brain parenchyma every few hours (Hanisch and Kettenmann, 2007; Nimmerjahn et al., 2005).
Under pathological conditions like injury or inflammation microglia become activated immune cells that show an amoeboid morphology, migrate to and within the lesion site, can clear apoptotic cells by phagocytosis and release a wide range of soluble factors that include neurotrophins and immunomodulatory factors (Biber et al., 2007; Block et al., 2007; Hanisch and Kettenmann, 2007). However, in some neurodegenerative diseases like Alzheimer's disease and multiple sclerosis, microglia become over-activated and have detrimental effects on neurons by releasing cytotoxic factors like nitric oxide and tumor necrosis factor-alpha (Block et al., 2007).
Microglial function is often studied using primary microglial cells, which are isolated and enriched from mixed glial cultures derived from the brains of postnatal mice or rats. A restricted number of microglial cells are obtained by a shaking procedure from mixed glial culture flasks (Giulian and Baker, 1986). Optionally, a purified population of microglial cells can be obtained using density gradients and flow cytometry sorting (Ford et al., 1995). Human primary microglia have also been obtained in very limited numbers from patients undergoing neurosurgery or from autopsy brains obtained after a short post mortem interval (Lafortune et al., 1996)
However, the obtained number of primary microglia is very limited in rodents and humans, which complicates classical biochemistry studies, systematic screening tests, or cell therapy approaches. In addition to primary cells, a murine microglial cell line (BV2) was developed by oncogenic transformation of primary microglia (Blasi et al., 1990; Bocchini et al., 1992). Furthermore, an immortalised human microglial cell line (HMO6) was developed through retroviral transduction of human embryonic telencephalon tissue with v-myc (U.S. Pat. No. 6,780,641). However, a drawback of all these cell lines is that they showed altered cytokine profile and changes in their migratory capacity (Horvath et al., 2008).
Recently, differentiation of microglia-like cells from mouse embryonic stem (ES) cells was described using a five-step protocol following neuronal differentiation (Tsuchiya et al., 2005). Tsuchiya et al. succeeded in differentiating Mac1+ cells into macrophages as well as into microglia and in isolating microglial cells that were positively stained for Iba1 and CD45, by a density gradient method. The isolated cells showed morphological characteristics of primary microglia and migrate from the bloodstream to brain parenchyma in mice. However, these cells were not described to survive and proliferate in culture (Tsuchiya et al., 2005). Recently, several microglial precursor cell lines were generated from murine ES cells (Napoli et al., 2009). The murine ES cell-derived microglial precursor (ESdM) lines were propagated in culture and expanded to high cell numbers. ESdM were indistinguishable by their cell surface receptors from primary microglia and showed migratory and phagocytic capacity comparable to primary microglia. After intracerebral transplantation in postnatal mice, they engrafted as microglial cells into the brain tissue.
However, despite the above described advances in the establishment of microglia precursor cell cultures, there is still the need to provide methods for the preparation of high quality human microglial precursor cells that can be obtained in large quantities.
SUMMARY
Accordingly, the present disclosure relates to a method for obtaining human microglial precursor cells, comprising: (a) providing a cell population comprising neural precursor cells, wherein the cell population is obtainable from embryoid bodies differentiated from human pluripotent stem cells; (b) differentiating the cell population comprising neural precursor cells into microglial precursor cells by culturing in medium comprising a growth factor selected from the group consisting of insulin and insulin-like growth factors; (c) expanding and enriching microglial precursor cells in medium comprising a growth factor selected from the group consisting of insulin and insulin-like growth factors and comprising 10 to 150 ng/ml GM-CSF; and (d) isolating microglial precursor cells comprising CD45-positive cells.
In accordance with the present disclosure, the term “microglial precursor cells” relates to a population of cells comprising partially differentiated cells, derived from myeloid precursor cells and capable of further differentiating into microglial cells. Myeloid precursor cells are characterized by the expression of the transcription factor PU.1 (Iwasaki et al. (2005). Microglia are further characterized by a ramified morphology with processes interdigitating with other glial cells and neurons and in surveying their local environment (Ransohoff and Perry, 2009). Furthermore, upon transplantation of microglial precursor cells into tissues comprising neurons and astrocytes, they integrate into these tissues as microglia (Tsuchiya et al., 2005; Napoli, 2008). In addition, upon contact of microglial precursors with neurons and/or astrocytes or addition of growth factors such as macrophage colony-stimulating factor, they can transform into microglia (Liu et al., 1994). The population of “microglial precursor cells” may comprise cells at different stages of differentiation between myeloid precursor cells and microglia. Thus, also fully differentiated microglial cells may be comprised in the population of microglial precursor cells. Non-differentiated stem cells as well as neural or mesenchymal stem cells are not comprised in the term “microglial precursor cells”.
Preferably, the microglial precursor cells are a population comprising at least 70% of cells expressing the markers of CD45, CD11b, CD11c, CD14, CD16, integrin-alpha4, inegrin-beta1, CX3CR1 and TREM2 and being inducible to express TNF-alpha, interleukin-1 beta, nitric oxide synthase-2, CCL2, CXCL9 and/or CXCL10 (Napoli, 2008). More preferably, at least 80%, such as at least 90%, at least 95% and most preferably 100% of the cells express the markers CD45, CD11b, CD11c, CD14, CD16, integrin-alpha4, integrin-beta1, CX3CR1 and TREM2 and being inducible to express TNF-alpha, interleukin-1 beta, nitric oxide synthase-2, CCL2, CXCL9 and/or CXCL10.
The term “neural precursor cells” refers to cells of neuroectodermal origin that are capable of differentiating into various neural cell types. Such neural cell types include for example neurons, astrocytes and oligodendrocytes. Neuroectodermal cells are characterized by the expression of SOX1, an HMG box transcription factor (Pevny et al., 1998).
The “cell population comprising neural precursor cells” preferably is a population comprising at least 70% of neural precursor cells, more preferably at least 80%, such as at least 90%, at least 95% and most preferably 100% neural precursor cells. The cell population may further comprise a small number (e.g. 5%, 10%, 20% or 30%) of stem cells showing mesenchymal properties, and which are derived from SOX1-positive neuroectodermal cells (Takashima et al., 2007).
The term “embryoid bodies” as used herein refers to aggregates of cells derived from pluripotent stem cells. Embryoid bodies (embryoid body) are generally comprised of a large variety of differentiated cell types. Cell aggregation is for example imposed by hanging drop or other methods that prevent cells from adhering to a surface, thus allowing the embryoid bodies to form their typical colony growth. Upon aggregation, differentiation is typically initiated and the cells begin to a limited extent to recapitulate embryonic development.
The term “pluripotent stem cells”, in accordance with the present disclosure, relates to a cell type having the capacity for self-renewal, an ability to go through numerous cycles of cell division while maintaining the undifferentiated state, and the potential of differentiation, i.e. the capacity to differentiate into specialized cell types. Pluripotent stem cells are the descendants of totipotent cells and can differentiate into nearly all cells, i.e. cells derived from any of the three primary germ layers: ectoderm, endoderm, and mesoderm. The term pluripotent stem cells also encompasses stem cells derived from the inner cell mass of an early stage embryo known as a blastocyst. Recent advances in embryonic stem cell research have led to the possibility of creating new embryonic stem cell lines without destroying embryos, for example by using a single-cell biopsy similar to that used in preimplantation genetic diagnosis (PGD), which does not interfere with the embryo's developmental potential (Klimanskaya et al., 2006). Furthermore, a large number of established embryonic stem cell lines are available in the art (according to the U.S. National Institutes of Health, 21 lines are currently available for distribution to researchers), thus making it possible to work with embryonic stem cells without the necessity to destroy an embryo.
In a preferred embodiment, the pluripotent stem cells are not human embryonic stem cells.
In an alternative preferred embodiment, the pluripotent stem cells are induced pluripotent stem cells. “Induced pluripotent stem (iPS) cells”, in accordance with the present disclosure, are pluripotent stem cells derived from a non-pluripotent cell, typically an adult somatic cell, by inducing a “forced” expression of certain genes. Induced pluripotent stem cells are identical to natural pluripotent stem cells, such as e.g. embryonic stem cells, in many respects including for example the expression of certain stem cell genes and proteins, chromatin methylation patterns, doubling time, embryoid body formation, teratoma formation, viable chimera formation, and potency and differentiability. Induced pluripotent stem cells are an important advancement in stem cell research, as they allow researchers to obtain pluripotent stem cells without the use of embryos (Nishikawa et al., 2008). The induced pluripotent stem cells may be obtained from any adult somatic cell, preferably from fibroblasts, such as for example from skin tissue biopsies.
Methods for the generation of human induced pluripotent stem cells are well known to the skilled person. For example, induced pluripotent stem cells can be generated from human skin tissue biopsies (Park and Daley, 2009; Park et al., 2008). Fibroblasts are grown in MEM-medium containing chemically defined and recombinant serum components. For reprogramming, the human fibroblasts are retrovirally transduced with OCT4, SOX2, c-MYC and NANOG genes. For this, genes are cloned into a retroviral vector and transgene-expressing viral particles are produced in the HEK293FT cell line. Human skin fibroblasts are co-transduced with all four vectors. The obtained iPS cells are cultured according to protocols established for human embryonic stem cells in DMEM-medium containing serum replacement factors and recombinant growth factors. The iPS cells are analyzed for normal morphology and normal karyotype and are studied by fingerprinting analysis and immunostaining for OCT3/4, NANOG, SSEA-3, SSEA-4, Tra-1-60 and Tra-1-81. Gene transcripts for OCT4, SOX2, NANOG, KLF4, c-MYC, REX1, GDF3 and hTERT are analyzed by real-time RT-PCR. Furthermore, multilineage differentiation of iPS cells is confirmed by embryoid body, teratoma formation and differentiation into adult cell types (Choi et al., 2009; Zhang et al., 2009). As another example, human iPS cells can also be obtained from embryonic fibroblasts without viral integration using adenoviral vectors expressing c-Myc, Klf4, Oct4, and Sox2 (Zhou and Freed, 2009).
The term “a cell population obtainable from embryoid bodies differentiated from human pluripotent stem cells” as used in accordance with the present disclosure refers to a cell population comprising neural precursor cells having the same characteristics as a cell population obtained after inducing human pluripotent stem cells to form embryoid bodies and culture them under conditions that allow the expansion of nestin-positive cells.
The “growth factor” as used herein refers to a factor capable of stimulating cellular growth, proliferation and differentiation. The term “a growth factor selected from the group consisting of insulin and insulin-like growth factors” refers to a growth factor selected from insulin and polypeptides with high sequence similarity to insulin, in particular insulin-like growth factor 1 (IGF-1) and insulin-like growth factor 2 (IGF-2).
The growth factor selected from the group consisting of insulin and insulin-like growth factors may be comprised in the medium in amounts of between 5 to 500 μg/ml, preferably between 10 to 350 μg/ml, more preferably between 15 to 200 μg/ml, such as for example 18 to 100 μg/ml, such as for example 22 to 50 μg/ml and most preferably at about 25 μg/ml.
Preferably, the differentiation of the cell population comprising neural precursor cells into microglial precursor cells in step (b) is carried out in the absence of feeder cells.
Appropriate culture media are known in the art and comprise, for example, media containing L-glutamine, D-glucose, insulin, transferrin, progesterone, putrescine and/or sodium-selenite. For example, a preferred medium for differentiating the cell population comprising neural precursor cells into microglial precursor cells in step (b) is N2-medium, i.e. a Dulbecco's Modified Eagle Medium: Nutrient Mixture F-12 (DMEM/F12)-based medium comprising 0.48 mM L-glutamine, 5.3 μg/ml D-glucose, 25 μg/ml insulin, 100 μg/ml transferrin, 6.3 ng/ml progesterone, 16.11 μg/ml putrescine and 5.2 ng/ml sodium-selenite. In accordance with the present disclosure, the cell culture medium employed in step (b) lacks FGF2, which, together with the absence of self-renewal signals usually produced by feeder layers, leads to spontaneous differentiation of the cells into embryoid bodies.
A preferred medium for expanding and enriching microglial precursor cells in step (c) is also N2-medium as defined above, further comprising 10 to 150 ng/ml GM-CSF as characterised in step (c).
The term “GM-CSF” as used herein refers to granulocyte-macrophage colony-stimulating factor, a cytokine that functions as a white blood cell growth factor (Wong et al., 1985; Lee et al., 1985). GM-CSF stimulates stem cells to produce granulocytes (neutrophils, eosinophils, and basophils) and monocytes and is secreted by macrophages, T cells, mast cells, endothelial cells and fibroblasts. GM-CSF may be comprised in the medium in amounts of 10 to 150 ng/ml, preferably between 30 to 130 ng/ml, more preferably between 50 and 120 ng/ml, such as for example 70 to 110 ng/ml and most preferably at about 100 ng/ml.
The term “expanding”, in accordance with the present disclosure, refers to a multiplication of cells, thus resulting in an increase in the total number of microglial precursor cells. Preferably, cells are expanded to at least twice their original number, more preferably to at least 10 times their original number, such as for example at least 100 times, such as at least 1,000 times their original number and most preferably to at least 10,000 times, such as at least 100,000 times their original number.
Expansion of microglial precursor cells may be achieved by known methods, e.g. by culturing the cells under appropriate conditions to high density and subsequent splitting (or passaging) of the cells, wherein the cells are re-plated at a diluted concentration into an increased number of culture dishes or onto solid supports. With increasing passage number, the amount of cells obtained therefore increases due to cell division.
In accordance with the present disclosure, the term “enriching” refers to a selective accumulation of microglial precursor cells, thus resulting in an increase of the number of microglial precursor cells as compared to the number of cells that are not microglial precursor cells. Preferably, cells are enriched such that at least 70% of the cell population are microglial precursor cells. More preferably, at least 80%, such as at least 90%, at least 95%, at least 98%, such as at least 99% and most preferably 100% of the cell population are microglial precursor cells.
Enrichment of microglial precursor cells may be achieved by any method known in the art. For example, microglial precursor cells appear as rounded, bright shining cells that can be distinguished from neurons by their cellular body. Therefore, microglial precursor cells can be identified by their morphology and can be mechanically isolated and transferred to a solid support, such as for example a different cell culture dish or flask. Mechanical isolation relates to the manual selection and isolation of cells, preferably under a microscope and may be performed by methods known in the art, such as for example aspiration of the cells into the tip of pipette or detaching of the cells using a cell scraper or density gradient centrifugation (Kamihira and Kumar, 2007).
As an alternative exemplary method of enriching microglial precursor cells, the cells may be maintained in culture as defined in step (c) for a prolonged period of time, such as for example two or more weeks until the microglial precursor cells have overgrown the remaining cell types, which do not survive under these conditions. During this prolonged culture period, the medium is preferably replaced with fresh medium. Most preferably, the medium is replaced ever second day.
Further methods of enrichment include, without being limiting, cell sorting approaches such as magnetic activated cell sorting (MACS) or flow cytometry activated cell sorting (FACS), panning approaches using immobilised antibodies or the use of density gradients. All these methods are known to the person skilled in the art and have been described, for example in Dainiak et al., 2007.
Methods of isolating microglial precursor cells comprising CD45-positive cells are well-known in the art and comprise, without being limiting, cell sorting approaches such as for example the above mentioned methods of magnetic activated cell sorting (MACS), flow cytometry activated cell sorting (FACS), panning approaches using immobilised antibodies, high-throughput fluorescence microscopy or density gradient approaches. Any surface protein expressed, preferably selectively expressed (i.e. not expressed or not expressed to a significant amount on other cell types present in the culture), on microglial precursor cells may be employed for this isolation, as long as the cells thereby obtained comprise CD45-positive cells. Such surface proteins are described further below. Preferably, the isolation is carried out based on the surface protein CD45. In accordance with the present disclosure, the term “microglial precursor cells comprising CD45-positive cells” refers to a cell population comprising at least 70% of cells expressing the marker CD45. More preferably, at least 80%, such as at least 90%, at least 95%, at least 98%, such as at least 99% and most preferably 100% of the cells express the marker CD45.
“CD45”, as used herein, refers to “cluster of differentiation 45” and is a membrane tyrosine phosphatase that is used as a marker to distinguish cells of the hematopoietic lineage from the endothelial lineage. CD45 is uniformly distributed in the plasma membrane and constitutes up to 10% of the molecules on the surface of expressing cells (Ford et al., 1995).
In accordance with the present disclosure, it was surprisingly found that human pluripotent stem cells can be differentiated into microglial precursor cells in cell culture.
So far, methods employing human microglial precursor cells are severely limited by the fact that the only available human microglial precursor cell lines are either primary cell lines or immortalised human microglial cell lines, which are obtained by retroviral transduction of cells. Both of these cell lines have drawbacks. Primary cell lines can only be obtained in limited numbers, which often is insufficient for classical biochemistry studies, systematic screening tests, or cell therapy approaches. Immortalised human microglial cell lines, on the other hand, have the drawback that due to the transformation they potentially have an altered cytokine profile and therefore show changes in their behaviour such as their migratory capacity.
The present disclosure now provides a method of preparing human microglial precursor cells that are of high quality and can be obtained in large quantities. The method thus provides the advantage of providing human microglial precursor cells as a cell line that can be amplified and maintained for a prolonged period of time, thus providing a sufficiently high number of cells for carrying out research, such as for example research and validation studies of pharmaceutical compositions for use in the central nervous system or toxicity studies such as for example for studying the inflammatory potential of substances, for example nanoparticles. Also, the microglial precursor cells obtained by the method of the present disclosure may be used in novel methods of cell therapy, such as in the treatment of neuro-degenerative, neuro-inflammatory or neuro-oncological diseases.
In a preferred embodiment of the method of the disclosure, the cell population comprising neural precursor cells in step (a) is obtained by: (i) growing human pluripotent stem cells in suspension culture until embryoid bodies have formed; (ii) transferring the embryoid bodies onto a solid support under conditions suitable to allow attachment of the embryoid bodies and culturing the embryoid bodies until the embryoid bodies have attached to the solid support; (iii) changing the medium to neural precursor selection medium comprising (1) a growth factor selected from the group consisting of insulin and insulin-like growth factors, (2) 5 to 100 ng/ml FGF2 and (3) 2.5 to 25 μg/ml fibronectin or 5 to 50 ng/ml laminin and culturing the embryoid bodies for at least 10 days; and (iv) expanding nestin-positive cells in medium comprising a growth factor selected from the group consisting of insulin and insulin-like growth factors and comprising 5 to 100 ng/ml FGF2 and 5 to 50 ng/ml laminin for at least 7 days.
The term “suspension culture” as used herein refers to the culture of cells such that the cells do not adhere to the solid support or the culture vessel. To transfer cells into a suspension culture, they are for example removed from the culture dish by a cell scraper and transferred to sterile dishes (e.g. bacterial dishes) containing culture medium, which do not allow adhesion of the cells to the surface of the dish. Thus, the cells are cultured in suspension without adherence to a matrix or the bottom of the dish.
The term “solid support”, in accordance with the present disclosure, refers to a surface enabling the adherence of cells thereto. Said surface may be, for example, the wall or bottom of a culture vessel, a plastic or glass slide such as for example a microscope slide or (a) bead(s) offering a surface for adherence.
“Conditions suitable to allow attachment”, as referred to herein, are well known to the skilled person and have been described, for example, in Schmitz, 2009. Preferably, said conditions are achieved by coating the solid support with an agent that enhances attachment of cells to the solid support. Such coating agents as well as methods of using them are also well known in the art and include, without being limiting, poly-L-lysin, gelatine, poly-L-ornithin, collagen, tenascin, perlecan, phosphocan, brevican, neurocan, thrombospondin, fibronectin and laminin, as for example described in the examples below.
The terms “FGF2”, “fibronectin” and “laminin” are used according to the definitions provided in the art. Thus, FGF2 refers to the basic fibroblast growth factor, a member of the fibroblast growth factor family, also referred to as bFGF or FGF-β in the art (Kurokawa et al., 1987).
Fibronectin refers to a high-molecular weight (˜440 kDa) extracellular matrix glycoprotein that binds to integrins but also to other extracellular matrix components such as collagen, fibrin and heparan sulfate proteoglycans (e.g. syndecans) (Ruegg et al., 1992).
Laminin refers to a family of glycoproteins that are an integral part of the structural scaffolding in almost every tissue of an organism. They are secreted and incorporated into cell-associated extracellular matrices. Fibronectin and laminin promote attachment, spreading, and proliferation of cells in cell culture (Vuolteenaho et al., 1990; Durkin et al., 1997).
FGF2 may be comprised in the medium in amounts of between 5 to 100 ng/ml, preferably between 8 to 75 ng/ml, more preferably between 12 and 50 ng/ml, such as for example 15 to 40 ng/ml, such as for example 17 to 30 ng/ml and most preferably at about 20 ng/ml.
Fibronectin may be comprised in the medium in amounts of between 2.5 to 25 μg/ml, preferably between 3 to 20 μg/ml, more preferably between 3.5 to 15 μg/ml, such as for example 4 to 10 μg/ml, such as for example 4.5 to 8 μg/ml and most preferably at about 5 μg/ml.
Laminin may be comprised in the medium in amounts of between 5 to 50 ng/ml, preferably between 8 to 40 ng/ml, more preferably between 12 and 30 ng/ml, such as for example 15 to 25 ng/ml, such as for example 17 to 22 ng/ml and most preferably at about 20 ng/ml.
The term “nestin-positive cells”, as used herein, refers to cells expressing the marker nestin, which is a type VI intermediate filament protein.
In addition to the media defined above, another exemplary medium to be used in the method of the present disclosure, in particular in step (iii) is B27-medium, i.e. a Dulbecco's Modified Eagle Medium: Nutrient Mixture F-12 (DMEM/F12)-based medium comprising 0.2 mM L-glutamine, 15.6 μg/ml D-glucose, 25 μg/ml insulin, 30 nM sodium-selenite and 50 μg/ml transferrin.
In another preferred embodiment of the method of the disclosure, the cells are further cultured after step (d) for at least 2 passages in medium comprising 10 to 150 ng/ml GM-CSF and a growth factor selected from the group consisting of insulin and insulin-like growth factors on a solid support under conditions suitable to allow attachment of the cells.
In a more preferred embodiment, the microglial precursor cells are, following the culturing for 2 passages, maintained in medium comprising a growth factor selected from the group consisting of insulin and insulin-like growth factors. In an alternative embodiment, the microglial precursor cells obtained according to the method of the disclosure are maintained in medium comprising a growth factor selected from the group consisting of insulin and insulin-like growth factors, without the above described further culturing step for at least 2 passages in medium comprising 10 to 150 ng/ml GM-CSF and a growth factor selected from the group consisting of insulin and insulin-like growth factors on a solid support under conditions suitable to allow attachment of the cells.
It was found in accordance with the present disclosure, that the cells obtained with the method of the disclosure can proliferate without addition of any of the growth factors GM-CSF, M-CSF or IL-3 to medium. Furthermore, the microglial precursor cells are capable of attaching to solid supports without requiring the coating with any coating agents, such as poly-L-lysin. However, it is preferred that the initial at least two passages are carried out in the presence of said factors in order to increase attachment and proliferation rate.
In a further preferred embodiment of the method of the disclosure, enriching in step (c) comprises transferring microglial precursor cells onto a solid support under conditions suitable to allow attachment of the cells.
As outlined above, the microglial precursor cells may be enriched using various methods known in the art. In accordance with this preferred embodiment, the cells are actively enriched, for example by the methods referred to above such as mechanical isolation based on morphology, cell sorting approaches, panning methods as well as the use of density gradients. Using these methods, microglial precursor cells are isolated and then transferred onto a solid support. Preferably, the microglial precursor cells are enriched by mechanical isolation based on morphology, such as for example described in the examples below.
In another preferred embodiment of the method of the disclosure, the medium in step (c) and/or the medium employed for growing the microglial precursor cells for the initial at least two passages further comprises up to 50 ng/ml M-CSF.
The term “M-CSF” as used herein refers to macrophage colony-stimulating factor, a secreted cytokine which influences hematopoietic stem cells to differentiate into macrophages or other related cell types (Takahashi et al., 1989). M-CSF may be comprised in the medium in amounts of up to 50 ng/ml, preferably between 1 to 40 ng/ml, more preferably between 3 and 30 ng/ml, such as for example 5 to 20 ng/ml, such as for example 7 to 15 ng/ml and most preferably at about 10 ng/ml.
In another preferred embodiment of the method of the disclosure, the medium in step (c) and/or the medium employed for growing the microglial precursor cells for the initial at least two passages further comprises up to 50 ng/ml IL-3.
The term “IL-3” as used herein refers to interleukin-3, an interleukin, that stimulates the differentiation of multipotent hematopoietic stem cells into myeloid progenitor cells as well as stimulating the proliferation of the cells of the myeloid lineage (erythrocytes, thrombocytes, granulocytes, monocytes, and dendritic cells) (Yang et al., 1986). IL-3 is secreted by activated T cells. IL-3 may be comprised in the medium in amounts of up to 50 ng/ml, preferably between 1 to 40 ng/ml, more preferably between 3 and 30 ng/ml, such as for example 5 to 20 ng/ml, such as for example 7 to 15 ng/ml and most preferably at about 10 ng/ml.
In a further preferred embodiment of the method of the disclosure, the medium in step (b) further comprises between 5 to 50 ng/ml laminin. Preferred amounts of laminin are as defined above.
In another preferred embodiment of the method of the disclosure, the concentration of FGF2 in the neural precursor selection medium in step (iii) is about 20 ng/ml and the amount of fibronectin is about 5 μg/ml.
In a further preferred embodiment of the method of the disclosure, the concentration of FGF2 in the medium in step (iv) is about 20 ng/ml and the amount of laminin is about 10 ng/ml.
In another preferred embodiment of the method of the disclosure, the medium in step (b) and/or the medium employed for growing the microglial precursor cells for the initial at least two passages comprises about 100 ng/ml GM-CSF, about 10 ng/ml M-CSF and about 10 ng/ml IL-3.
Any of the supplemental factors mentioned herein, e.g. insulin, insulin-like growth factor, GM-CSF, FGF2, fibronectin, laminin, poly-L-lysin, M-CSF and IL-3 may be obtained by methods well known in the art. Thus, they may for example be obtained by recombinant production or they may be obtained from natural sources. Furthermore, these factors may be present in the form of mixtures of factors, such as for example serum.
For recombinant production, for example, nucleic acid sequences encoding the above mentioned factors can be synthesized by PCR and inserted into an expression vector. Subsequently a suitable host may be transformed with the expression vector. Thereafter, the host is cultured to produce the desired factor, which is isolated and purified. Such methods are well known in the art (see, e.g., Sambrook et al., supra). An alternative method is in vitro translation of mRNA. Suitable cell-free expression systems include rabbit reticulocyte lysate, wheat germ extract, canine pancreatic microsomal membranes, E. coli S30 extract, and coupled transcription/translation systems such as the TNT-system (Promega).
In addition to recombinant production, the above mentioned factors may be produced synthetically, e.g. by direct protein synthesis using solid-phase techniques (cf. Stewart et al. (1969): Solid Phase Peptide Synthesis; Freeman Co, San Francisco; Merrifield, J. Am. Chem. Soc. 85 (1963), 2149-2154). Synthetic protein synthesis may be performed using manual techniques or by automation. Automated synthesis may be achieved, for example, using the Applied Biosystems 431A Peptide Synthesizer (Perkin Elmer, Foster City Calif.) in accordance with the instructions provided by the manufacturer. Various fragments may be chemically synthesized separately and combined using chemical methods to produce the full length molecule. Furthermore, the above mentioned factors may also be produced semi-synthetically, for example by a combination of recombinant and synthetic production.
Preferably, the supplemental factors insulin, insulin-like growth factor, GM-CSF, FGF2, M-CSF and IL-3 are human proteins. More preferably, these factors are obtained by recombinant production.
In a further preferred embodiment of the method of the disclosure, the isolation of microglial precursor cells comprising CD45-positive cells in step (d) is performed by magnetic activated cell sorting (MACS) or flow cytometry activated cell sorting (FACS).
In another preferred embodiment of the method of the disclosure, the microglial precursor cells are characterised by the expression of CD45, CD11b, CD68, Iba1, integrin-alpha 4, inegrin-beta 1, CX3CR1 and TREM2.
All of these molecules characterising microglial precursor cells are defined in accordance with the present disclosure in the same manner as known in the prior art and the common general knowledge of the skilled person.
In accordance with the present disclosure, “CD11b” relates to cluster of differentiation 11b, a subunit of Mac-1, which is a complement receptor (“CR3”) consisting of CD11b and CD18.
“CD68”, in accordance with the present disclosure, relates to cluster of differentiation 68, a glycoprotein which binds to low density lipoprotein. It is expressed on monocytes/macrophages.
In accordance with the present disclosure, “Iba1” relates to ionized calcium binding adaptor molecule 1, a 17-kDa EF-hand protein that is specifically expressed in macrophages/microglia and is upregulated during the activation of these cells. Among brain cells, the Iba1 gene is specifically expressed in microglia. Upon activation of microglia due to inflammation, expression of Iba1 is upregulated allowing the detection of activated microglia.
The term “integrin-alpha 4”, as used herein, refers to the α4 integrin subunit expressed on the cell membrane as a heterodimer non-covalently associated with the β1 or the β7 integrin chains. α4 integrins have a key function in the adhesion interaction between stem/progenitor cells and the stromal microenvironmental cells and their matrix within the bone marrow.
In accordance with the present disclosure, “integrin-beta 1”, also known as ITGB1 or CD29, is an integrin unit associated with very late antigen receptors.
The term “CX3CR1” as used herein, refers to the only member of the CX3C sub-family of chemokine receptors. This receptor binds the chemokine CX3CL1 (described above), which is also known as neurotactin or fractalkine. Expression of this receptor is mainly associated with macrophages and monocytes (Jung et al., 2000).
“TREM2”, in accordance with the present disclosure, refers to the triggering receptor expressed on myeloid cells 2, and is believed to have a role in chronic inflammation and the stimulation of production of constitutive rather than inflammatory chemokines and cytokines (Schmid et al., 2002; Takahashi et al., 2005). TREM2 forms a receptor signaling complex with TYROBP and triggers activation of the immune responses in macrophages and dendritic cells.
In a further preferred embodiment of the method of the disclosure, the microglial precursor cells are further characterized by an at least 2 fold increased expression of the gene transcripts for TNF-alpha, IL-1 beta, nitric oxide synthase-2, CCL2, CXCL9 and/or CXCL10 after stimulation with LPS as compared to cells not stimulated with LPS.
Also these inducible molecules characterizing microglial precursor cells are defined in accordance with the present disclosure in the same manner as known in the prior art and the common general knowledge of the skilled person.
“TNF-alpha”, in accordance with the present disclosure, refers to tumor necrosis factor alpha, which is a cytokine involved in systemic inflammation and is a member of a group of cytokines that stimulate the acute phase reaction. TNF-alpha primarily regulates immune cells, but is also able to induce apoptotic cell death, to induce inflammation, and to inhibit tumorigenesis and viral replication. Dysregulation and, in particular, overproduction of TNF-alpha have been implicated in a variety of human diseases, as well as cancer. TNF-alpha is produced mainly by macrophages, but also by a broad variety of other cell types including lymphoid cells, mast cells, endothelial cells, cardiac myocytes, adipose tissue, fibroblasts, and neuronal tissue. Large amounts of TNF-alpha are released in response to lipopolysaccharide, other bacterial products, and IL-1 (interleukin-1).
In accordance with the present disclosure, “IL-1 beta” refers to a cytokine and is a member of the interleukin-1 cytokine family. IL-1 beta is produced by activated macrophages as a proprotein, which is proteolytically processed to its active form by caspase-1 (CASP1/ICE). IL-1 beta is an important mediator of the inflammatory response, and is involved in a variety of cellular activities, including cell proliferation, differentiation, and apoptosis.
As used herein, “nitric oxide synthase-2” belongs to a family of enzymes that carry out a 5′-electron oxidation of L-arginine with the aid of tetrahydro-biopterin. Nitric oxide synthase (NOS) enzymes contribute to the transmission between neurons, to the immune system and to dilating blood vessels. They do so by synthesis of nitric oxide (NO) from the terminal nitrogen atom of L-arginine in the presence of NADPH and dioxygen (O 2 ). Induction of the nitric oxide synthase-2 usually occurs in an oxidative environment, and thus high levels of nitric oxide have the opportunity to react with superoxide leading to peroxynitrite formation and cell toxicity. These properties are believed to define the roles of nitric oxide synthase-2 in host immunity, enabling its participation in anti-microbial and anti-tumor activities as part of the oxidative burst of macrophages.
In accordance with the present disclosure, “CCL2” refers to the chemokine (C-C motif) ligand 2. CCL2 is a small cytokine belonging to the CC chemokine family that is also known as monocyte chemotactic protein-1 (MCP-1). CCL2 recruits monocytes, memory T cells, and dendritic cells to sites of tissue injury and infection. Cell surface receptors that bind CCL2 are CCR2 and CCR4.
“CXCL9”, as used throughout the present disclosure, refers to chemokine (C-X-C motif) ligand 9. CXCL9 is a small cytokine belonging to the CXC chemokine family that is also known as monokine induced by gamma interferon (MIG). CXCL9 is a T-cell chemo-attractant, which is induced by IFN-γ. CXCL9 elicits its chemotactic functions by interacting with the chemokine receptor CXCR3.
In accordance with the present disclosure, “CXCL10” refers to chemokine (C-X-C motif) ligand 10. CXCL10 is a small cytokine belonging to the CXC chemokine family that is also known as 10 kDa interferon-gamma-induced protein (γ-IP10 or IP-10). CXCL10 is secreted by several cell types in response to IFN-γ. These cell types include monocytes, endothelial cells and fibroblasts. CXCL10 has been attributed several roles, such as chemo-attraction for monocytes/macrophages, T cells, NK cells, and dendritic cells, promotion of T cell adhesion to endothelial cells, antitumor activity, and inhibition of bone marrow colony formation and angiogenesis. This chemokine elicits its effects by binding to the cell surface chemokine receptor CXCR3.
It has been shown that microglial precursor cells can be induced by pro-inflammatory cytokines of the bacterial toxin LPS to express the above mentioned factors (Napoli, 2008; Carter et al., 2007; Hughes et al., 2002; Gourmala et al., 1997). Thus, microglial precursor cells are characterised by an at least 2-fold increased expression of the gene transcripts for TNF-alpha, IL-1 beta, nitric oxide synthase-2, CCL2, CXCL9 and/or CXCL10 after stimulation with LPS as compared to cells not stimulated with LPS.
In another preferred embodiment of the method of the disclosure, the cells obtained are free of pathogens. Such pathogens are well known to the skilled person and include, without being limiting, viruses such as for example Hepatitis virus A, B, C, Epstein-Barr-Virus or HIV-Virus and bacteria such as for example mycoplasm or chlamydia.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. In case of conflict, the patent specification, including definitions, will prevail.
BRIEF DESCRIPTION OF THE DRAWINGS
The file of this patent contains at least one drawing/photograph executed in color. Copies of this patent with color drawing(s)/photograph(s) will be provided by the Office upon request and payment of the necessary fee.
The figures show:
FIG. 1 . Undifferentiated iPS spontaneously differentiate into embryoid bodies (EBs) (day 8 of EB formation).
FIG. 2 . Outgrowth of plated EBs in the selection stage (day 4) in B27-medium.
FIG. 3 . Selection of nestin-positive cells 4 days in B27-medium.
FIG. 4 . Developing microglial-like colonies in culture after addition of the growth factors GM-CSF, IL-3 and M-CSF.
FIG. 5 . Isolated microglial precursor lines after 6 weeks of differentiation on PLL-coated dishes in N2-medium supplemented with GM-CSF, IL-3 and M-CSF.
FIG. 6 . Antibody against CD68 (left, DAPI right) immunostained about 98% of the isolated microglial precursors.
FIG. 7 . Antibody against Iba1 (left, DAPI right) immunostained about 98% of the isolated microglial precursors.
FIG. 8 . Coculture of GFP-transduced human microglia derived from induced pluripotent stem cells (iPSdM) and the glioma cell line U87. Cell number per culture dish of U87 glioma cells was determined under fluorescence microscope on day 0 (d0), day 1 (d1) and day 2 (d2) after coculture or culture of U87 alone. Microglial cells (iPSdM) reduced glioma cell number over time.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The examples illustrate the disclosure:
EXAMPLE 1
Differentiation of Human Induced Pluripotent Stem Cells to Microglial Precursors
For maintenance and expansion of human IFS, cells were cultured in chemically defined medium in the presence of 25 ng/ml recombinant human fibroblast growth factor-2 (rhFGF2) on a feeder layer. The absence of rhFGF2 and of self-renewal signals produced by feeder leads to spontaneous differentiation into embryoid bodies (EBs). EBs were kept in suspension for 8 days for spontaneous differentiation ( FIG. 1 ). Then, they were plated on poly-L-ornithin (PLO) and fibronectin-coated dishes and neural precursors were selected for 14 days in B27-medium (Gibco/BRL/Invitrogen) supplemented with 20 ng/ml rhFGF2 and 5 μg/ml fibronectin or 10 ng/ml laminin to enhance cell survival ( FIG. 2 ). In the selection stage, cells started to grow out and nestin-positive cells were the major population of developing cells ( FIG. 3 ). During expansion of nestin-positive cells in N2-medium (Gibco/BRL/Invitrogen) supplemented with 20 ng/ml rhFGF2 and 10 ng/ml laminin, the number of cells increased. Differentiation was initiated by withdrawal of the growth factors after 10 days of expansion. After 2 weeks, different cell types had developed and were characterized for their cell identity by immunocytochemistry. Immunocytochemistry for βIII-tubulin after 14 days of differentiation showed developing clusters of βIII-tubulin-positive cells.
After 6 weeks of differentiation, cultures were immunolabeled for βIII-tubulin, glial fibrillary acidic protein (GFAP), CD45 and CD68 to identify the developing cell types. GFAP-positive as well as βIII-tubulin-positive cells were detected within the cultures indicating a differentiation of the neural precursors to astrocytes and neurons, respectively. Co-immunolabeling for GFAP and βIII-tubulin shows no co-expression with CD45, indicating that the CD45-positive cell population is distinct from astrocytes and neurons. To enhance development of microglial precursors cells 100 ng/ml recombinant human granulocytemacrophage colony-stimulating factor (rhGM-CSF), 10 ng/ml recombinant human interleukin-3 (rhIL-3) and 10 ng/ml recombinant human macrophage colony-stimulating factor (rhM-CSF) were added to the media. After 2 days, first microglial precursors appeared in the culture ( FIG. 4 ) identified by immunostaining with antibodies directed against the hematopoietic marker protein CD45. After several days, approximately 2-10% of cells showed immunoreactivity for CD45. Cell colonies developed and microglial precursor lines proliferated in clusters within the mixed neural cultures.
EXAMPLE 2
Selection and Generation of Microglial Precursor Lines
For isolation of microglial precursor cells from the differentiated mixed culture a specific method was applied. Microglia-like cells identified by morphology were mechanically isolated by a micropipette and expanded on poly-L-lysine (PLL)-coated (5 μg/ml) dishes with the highest density possible for a monolayer. Mechanically isolated microglial precursors were cultured in the presence of 100 ng/ml rhGM-CSF, 10 ng/ml rhIL-3 and 10 ng/ml rhM-CSF. Growth factors are required for survival and proliferation of mechanically isolated microglial precursors. After expansion, cells expressing CD45 were sorted by magnetic activated cell sorting (MACS) or flow cytometry activated cell sorting (FACS) with antibodies directed against CD45. Sorted cells were cultured on PLL-coated dishes in N2 medium supplemented with 100 ng/ml rhGM-CSF, 10 ng/ml rhIL-3 and 10 ng/ml rhMCSF. After several days in culture, microglial precursor cell lines started to proliferate ( FIG. 5 ). The phenotype of the cells differed from ramified over bipolar structured till completely rounded cell morphology. Cells were isolated by trypsin or cell scraper and split 1:3 till 1:5 twice a week. Cell identity of microglial precursor lines was verified by immunocytochemistry for CD68 and Iba1 ( FIGS. 6 and 7 ).
EXAMPLE 3
Subcloning, Expansion and Quality Control of Microglial Precursor Lines
To obtain clones, single cells were mechanically isolated and transferred into separate PLL-coated (5 μg/ml) culture dishes. The isolated microglial precursor cells were cultured in DMEM/F12-medium (Gibco/BRL/Invitrogen) containing 100 ng/ml rhGM-CSF, 10 ng/ml rhIL-3 and 10 ng/ml rhM-CSF. Cells were cultured with high density and split 1:2. After splitting, cells recovered and attached again to the new PLL-coated dishes. Microglial precursors proliferated without addition of growth factors to medium after some passages and were passaged 1:3 till 1:5 twice a week. Microglial precursor cells were expanded to obtain at least 1×10 10 cells. Cells were analyzed by flow cytometry for expression of CD45, CD11b, CD11c, CD14, CD16, integrin-alpha4, integrin-beta1, CX3CR1 and TREM2. In addition, gene transcripts for TNF-alpha, interleukin-1 beta, nitric oxide synthase-2, CX3CL1, CCL2, CXCL9 and CXCL10 can be analyzed in the cells under normal and LPS-stimulation by real-time RT-PCR. The cells are confirmed by various test systems to be free of pathogens or contaminants (e.g. viruses etc.). Cells were aliquoted and frozen.
EXAMPLE 4
In Vitro Experiments with Human Induced Pluripotent Stem Cell Derived Microglia and Glioma
In vitro experiments were performed to confirm the functional activity of human iPS-derived microglia using the example of tumor growth. A co-culture of human GFP-transduced iPSdM and the human glioma cell line U87 was carried out using a ratio of 1:1 in co-culture. Starting the co-culture at day 0, every day total cell number of co-culture as well as the cell number of glioma in culture alone was counted under the microscope. Furthermore, the percentage of glioma and iPSdM in co-culture was measured by flow cytometry and the amount of glioma cells in the co-culture system was calculated ( FIG. 8 ). Thus, a reduced amount of glioma cells was detected in the co-culture compared to the culture of glioma cells alone and suggest that glioma cells were phagocytosed by iPSdM. Thus, the iPS-derived migroglia precursors of the present disclosure are functionally active.
Next, it was analysed whether glioma were phagocytosed by microglia using flow cytometry. Glioma cells were labeled with the red membrane dye PKH26 and iPSdM were visualized by lentiviral transduction with GFP. Both cell types were co-cultured at a ratio of 1:1. As control labeled glioma and GFP-transduced iPSdM were cultivated alone. After two days cells were analyzed by flow cytometry showing that about 97% of the green cells were also positive for a red fluorescent dye. This indicates that almost all iPSdM started to phagocyte red labeled glioma cells (data not shown).
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A method for obtaining human microglial precursor cells, comprising: (a) providing a cell population comprising neural precursor cells, wherein the cell population is obtainable from embryoid bodies differentiated from human pluripotent stem cells; (b) differentiating the cell population comprising neural precursor cells into microglial precursor cells by culturing in medium comprising a growth factor selected from the group consisting of insulin and insulin-like growth factors; (c) expanding and enriching microglial precursor cells in medium comprising a growth factor selected from the group consisting of insulin and insulin-like growth factors and 10 to 150 ng/ml GM-CSF; and (d) isolating microglial precursor cells comprising CD45-positive cells.
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CROSS REFERENCE TO RELATED PATENT APPLICATIONS
This application is a continuation of application Ser. No. 12/189,014 filed on Aug. 8, 2008 now U.S. Pat. No. 7,820,791, which is a continuation of application Ser. No. 11/587,018, filed Oct. 20, 2006, (now abandoned), which is a National Phase Application of International Application No. PCT/US2005/013415, filed Apr. 20, 2005, which claims priority to U.S. Provisional Application No. 60/563,939, filed Apr. 20, 2004, the entirety of which is incorporated herein by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
This invention was made with government support under Grant MH60997-02 awarded by the National Institute of Health. The government has certain rights in the invention.
TECHNICAL FIELD
This invention relates to biotechnology, more particularly to one or more members of the “cys-loop” ligand-gated ion channel superfamily, which are activated by a proton and/or H + /Na + exchange proteins, and methods of using the same.
BACKGROUND
Motor behaviors such as locomotion rely on precise signaling from the nervous system to coordinate various muscle activities. The neuromuscular junction has been extensively studied and a considerable amount of information exists on how information is communicated across the synapse between a motor neuron and a muscle cell. At the cellular level, depolarization of the motor neuron produces an action potential that is propagated to the presynaptic terminal. Depolarization causes the opening of voltage-gated calcium channels at the presynaptic terminal, resulting in an increase in intracellular calcium. In response to local increases in calcium, neurotransmitter filled vesicles fuse with the presynaptic plasma membrane, releasing their contents into the synaptic cleft. Postsynaptic ligand-gated ion channels on the muscle bind the neurotransmitter, resulting in the opening of an integral ion channel. Depending on an ion channel's permeability, the muscle is either hyperpolarized or depolarized.
Chemical synaptic transmission mediates fast and slow communication between cells, but it is not the only means of communication within the nervous system. Signals may also be conveyed nonsynaptically. In this case, a neurotransmitter or hormone is released at one site and slowly diffuses to distant target sites that are not in contact with the original site of release. This type of signaling is more suited to global, modulatory activities rather than functions requiring a rapid response. The interplay of synaptic and non-synaptic communication ultimately determines how a nervous system mediates particular behaviors.
In C. elegans , synaptic transmission has been extensively studied at the genetic, cellular and molecular levels. Most behaviors in the worm follow a simple paradigm in which information is directed from the sensory neurons to motor neurons to muscle, via synaptic contacts. However, the defecation cycle in C. elegans is a unique behavior in that it appears to be mediated by both synaptic, as well as nonsynaptic transmission (McIntire et al., 1993b; Thomas, 1990). Defecation in C. elegans is a stereotyped behavior that occurs every 50 seconds for the life of the animal, and is characterized by the coordinated activation of three independent muscle contractions (Croll, 1975; Thomas, 1990). The cycle is initiated with a posterior body contraction, followed by an anterior body contraction and finalized by an enteric muscle contraction, which expels intestinal contents. A simplified genetic pathway to explain the defecation behavior was proposed by Jim Thomas (Thomas, 1990) (see, FIG. 1B ). In this model, a clock mechanism keeps time independently of the motor program. At the appropriate interval, the clock first signals the posterior body contraction and then signals the common anterior body and enteric muscle contraction mechanism, which ultimately leads to activation of the individual muscle contractions (Liu and Thomas, 1994; Thomas, 1990) (FIG. 1B).
To determine the cellular basis of the defecation motor program, extensive cellular laser ablations have been performed. Based on these studies the motor neurons AVL and DVB were demonstrated to mediate the anterior body and enteric muscle contraction, but not posterior body contraction (McIntire et al., 1993b). The anterior body contraction is mediated by the motor neuron AVL, but the neurotransmitter that mediates this contraction is unknown (see, FIG. 1A). While AVL alone is required for anterior body contraction, both the AVL and DVB motor neurons serve a redundant function in activating the enteric muscles (see, FIG. 1A). Activation of the enteric muscles is GABA-dependent and is mediated by the EXP-I receptor (Beg and Jorgensen, 2003; McIntire et al., 1993a; McIntire et al, 1993b).
Interestingly, no known neurons are required to maintain the clock or initiate the posterior body contraction, suggesting that cycle timing and posterior body contraction are mediated by a non-neuronal mechanism (Liu and Thomas, 1994; McIntire et al., 1993b; Thomas, 1990) (see, FIG. 1A). Furthermore, mutations that disrupt classical neurotransmission and secretion do not affect the posterior body contraction. Taken together, these data suggest that posterior body contraction occurs through a non-neuronal mechanism that does not rely on classical or peptidergic neurotransmission.
Many genes have been identified that affect only specific aspects of the defecation motor program. It has been demonstrated that timekeeping of the cycle is controlled by an endogenous clock that resides in the intestine (Dal Santo et al., 1999). The cycle time is set by the activity of the itr-1 gene, which encodes an inositol triphosphate (IP3) receptor which mediates release of calcium from the smooth endoplasmic reticulum into the intestine every 50 seconds (Dal Santo et al., 1999). Mutations in the itr-1 gene slow down or eliminate the cycle, while overexpression accelerates the cycle. In the intestine, calcium levels oscillate with the same period as the defecation cycle (50 seconds) and peak calcium levels immediately precede the posterior body contraction (Dal Santo et al., 1999). Therefore, the frequency of intracellular calcium release in the intestine, determines the frequency of the defecation cycle.
It has been demonstrated that there is a one-to-one relationship between the calcium spike in the intestine and the execution of the posterior body contraction (Dal Santo et al., 1999). Normally, motor behaviors such as muscle contraction are mediated by the nervous system. Since neuronal input is not required to initiate the posterior body contraction, these muscles could be directly activated by a Ca 2+ regulated signal from the intestine.
BRIEF SUMMARY
In accordance with the purpose of this invention, as embodied and broadly described herein, this invention relates to an isolated or recombinant Na + /H + exchanger comprising an isolated or recombinant Na + /H + exchanger. The invention further relates to the PBO-4 Na + /H + exchanger and Na + /H + exchangers having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, and/or 99% identity to PBO-4 (SEQ ID NO:8). Optionally, the isolated or recombinant Na + /H + exchanger functions in the intestine.
The invention also relates to isolated or recombinant protein component of an H + -gated channel. The invention further relates to a H + -gated channel that is effected by extracellular Ca 2+ concentration. In particular, the invention relates to PBO-5 (SEQ ID NOs: 1 and 2) and/or PBO-8 (SEQ ID NOs: 3-5) and/or a H + -gated channel composed of PBO-5 and PBO-8. In addition the invention relates to isolated and/or recombinant proteins having at least 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, and/or 99% identity to PBO-5 and/or PBO-8. Further, the invention relates to a H + -gated channel that is pH sensitive. The invention further relates to a H + -gated cation channel.
The invention relates to compounds isolated from a vertebrate organism, wherein said compounds comprise at least a part of a H + -gated channel or Na + /H + exchanger. The invention further relates to a Na + /H + exchanger identified in a vertebrate organism.
The invention also relates to a method for identifying a component of a H + -gated channel in a vertebrate organism. For example, by screening a vertebrate organism for the presence of a component of a H + -gated channel; identifying the component of the H + -gated channel; and confirming that the component of the H + -gated channel is a component of said H + -gated channel. Optionally, the method further comprising isolating the component of said H + -gated channel.
The invention also relates to screening a component of a H + -gated channel for activation or inhibition by a candidate drug. The invention also relates to screening the component of a H + -gated channel for binding to HEPES and/or identifying mutations which prevent binding to HEPES.
The invention further relates to a protein produced by a process of screening a vertebrate organism for the presence of a component of a H + -gated channel; identifying said component of said H + -gated channel; and confirming that said component of said H-gated channel is a component of said H + -gated channel.
The invention further relates to compounds according to the invention identified in a mammal.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the disclosed method and compositions and together with the description, serve to explain the principles of the disclosed method and compositions.
FIG. 1 illustrates the defecation cycle behavior and genetics of the defecation cycle in C. elegans . FIG. 1A is a schematic drawing of the defecation cycle. Every 50 seconds a cycle is initiated by the posterior body contraction (pBoc), followed by an anterior body contraction (aBoc), and completed by an enteric muscle contraction, (Emc), which mediates expulsion of intestinal contents. Listed to the right are the motor neurons and neurotransmitters involved in each muscle contraction. FIG. 1B illustrates the genes involved and their affects on the cycle. A 50 second clock independently keeps time of the cycle. Each step of the defecation cycle can be specifically affected by mutation, demonstrating that cycle timing and muscle activation do not rely on one another. Muscle activation of each step occurs independently of the others. However, the anterior body contraction and the enteric muscle contraction share a common mechanism upstream of muscle activation.
FIG. 2 illustrates the structure and molecular cloning of pbo-5. The genomic location of pbo-5 is the last predicted gene on chromosome V, approximately 1.2 kb from the telomere. The middle of FIG. 2 illustrates the exon-intron structure of the pbo-5 gene. Positions of mutations in pbo-5 alleles are shown below the predicted protein structure. Triangles represent the peptide signal, the dotted line is the disulfide-bond, the transmembrane domains are labeled 1-4.
FIG. 3A-D show the sequence alignment of PBO-5 and cholinergic subunits. The amino acid sequence for C. elegans PBO-5, PBO-8 (F11C7.1; SEQ ID NO:5), UNC-29, UNC-38, and human alpha 7 nicotinic acetylcholine receptors subunits. Sequences were aligned using clustal X and identities are shaded and boxed. The black and hollow filled triangles denote the signal peptide sequence for PBO-5 and PBO-8, respectively. The dotted line shows the invariant disulfide bond present in all ligand-gated ion channels. Black bars denote the four transmembrane domains.
FIG. 4 shows the pbo-8 genomic structure and a phylogenetic tree. FIG. 4(A) shows the exon-intron structure of pbo-8. The pbo-8 locus consists of 13 exons that span 4.1 kb of the genome. FIG. 4(B) illustrate that PBO-5 and PBO-8 represent novel ligand-gated ion channel subunits. The PBO-5 and PBO-8 subunits cannot be categorized into one of the four ligand-gated ion channel families based on sequence analysis. Alignments were performed using clustal X and the bootstrap method with ‘neighbor-joining’ search was used to create the tree. Bootstrap values of 1,000 replicates are indicated on the tree.
FIG. 5 shows the expression pattern of pbo-5. FIGS. 5A and 5B are confocal images of animals expressing an integrated pbo-5::gfp fusion gene. The animals are oriented with anterior to the left, and posterior to the right. GFP expression is observed in the most posterior muscle cells ( FIG. 5A ) and in the neurons RIFL, RIFR, and RIS ( FIG. 5B ). FIG. 5C is a schematic drawing to illustrate pbo-5 expression within the context of the entire animal.
FIG. 6 illustrates the structure and molecular cloning of pbo-8. The top of FIG. 6 A represents the exon-intron structure of pbo-8; below, the predicted protein structure. The triangle represents the predicted signal peptide cleavage site, the dotted line represents the disulfide-bond, and the numbers 1-4 represent the four transmembrane domains. FIG. 6B shows the expression pattern of PBO-8. The left panel is a confocal image of an animal expressing a transcriptional pbo-5::gfp fusion gene. The right panel is a fluorescent image of an animal expressing a transcriptional pbo-8::gfp fusion gene fusion. PBO-8 expression is observed in the most posterior muscle cells, and has overlapping expression with PBO-5, suggesting PBO-8 may oligomerize with PBO-5 to form a functional receptor.
FIG. 7 shows a pH dose-response curve for PBO-5/PBO-8, which form a heteromultimeric H + -gated ion channel. PBO-5/PBO-8 expressing oocytes were voltage-clamped at −60 mV and a series of test pH applications (7.2-5.0) were bath applied for 5 seconds. Each point represents the mean current value normalized to the maximum and minimum values. A pH 50 =6.83±0.01 and Hill coefficient of 9+0.66 were determined for PBO-5/PBO-8 receptors (n =18). Error bars represent s.e.m. Inset, representative traces of PBO-5/PBO-8 dose-response experiments.
FIG. 8 shows PBO-5/PBO-8 ion selectivity. FIG. 8A shows the current-voltage (I-V) relationship of PBO-5/PBO-8 ion channels. The reversal potential determined under control conditions was 10.18±0.80 mV (n=13). Inset, representative traces of an experiment. Note, the strong inward rectification of PBO-5/PBO-8 receptors. FIG. 8B shows Na + permeability. Na ions were replaced with the cation NMDG, in Na + free Ringer's. There is a negative shift in reversal potential (E rev =−82.90±8.13 mV (n=6)) and the inward current in nearly abolished which suggests that Na is the primary charge carrier through the PBO-5/PBO-8 channel. FIG. 8C shows Cl − permeability. Chloride ions were replaced with the anion gluconate, in Cl − free Ringer's. The negligible shift in reversal potential demonstrates that chloride ions do not underlie the ionic conductance through PBO-5/PBO-8 channels (ΔE rev =0.25 mV, P>0.05, two-way ANOVA, (n=8).
FIG. 8D shows K + permeability. Replacement of K + for Na + in the extracellular solution demonstrates PBO-5/PBO-8 ion channels discriminate poorly between monovalent cations. Note the inward current is still present and there was not significant shift in reversal potential compared to control (P>0.05; two-way ANOVA, (n=4), demonstrating PBO-5/PBO-8 is a nonselective cation channel.
FIG. 9 shows calcium permeability. FIG. 9A shows the current-voltage (I-V) analysis of PBO-5/PBO-8 receptors under different Ca 2+ concentrations. Reversal potentials were measured under 1 mM Ca 2+ control and 3 mM and 10 mM test Ca 2+ conditions. Increasing extracellular Ca 2+ caused a positive shift in reversal potentials suggesting Ca 2+ is permeable to PBO-5/PBO-8 channels. Note the decreased inward current as extracellular Ca increased. FIG. 9B shows Ca 2+ permeability in Na + free Ringers. To better resolve Ca 2+ permeability, the I-V relationships where Ca 2+ was the only relevant extracellular ion were determined. These data demonstrate PBO-5/PBO-8 ion channels are Ca 2+ permeable.
FIG. 10 shows that Ca 2+ and H + compete at the PBO-5/PBO-8 activation site. FIG. 10A shows the results of normalized current amplitude versus test pH at four different extracellular Ca 2+ concentrations. Increasing Ca 2+ decreases the pH necessary for half-maximal activation. Currents were normalized to the maximal value at pH 6.0 for each [Ca 2+ ] o condition. FIG. 10B shows that a normalized current amplitude of test pH evoked responses at three Ca 2+ concentrations. Ca 2+ shifts activation but increasing extracellular does not affect maximal activation. Current were normalized to the value at 1 mM Ca 2+ for each pH tested.
FIG. 11 illustrates an exemplary embodiment for posterior body contraction in C. elegans . Every 50 seconds, a calcium spike occurs in the intestine the correlates with the initiation of the posterior body contraction. First, IP 3 receptors localized to the smooth endoplasmic reticulum in the intestine are activated every 50 seconds. Activation results in the intracellular rise of Ca 2+ in the intestine. Second, Ca 2+ binds to the C-terminal calmodulin-binding domain of PBO-4, thereby activating H + transport activity. Third, PBO-4 transports H + ions out of the intestine acidifying the pseudocoelomic space. Fourth, H + ions bind and activate the PBO-5/PBO-8 receptors expressed in posterior body wall muscle, thereby allowing Na + influx into the cell causing a depolarization and subsequent muscle contraction.
FIG. 12 illustrates the genetic mapping and molecular cloning of pbo-4. FIG. 12(A) illustrates the pbo-4 locus, which maps between daf-12 and egl-15 on the X chromosome. This region contains the cosmids T21B6 and K09C8. Rescue of the posterior body contraction defect by cosmid or subclone is indicated. Below this is an exon-intron structure of pbo-4. Mutations are indicated, black bars denote the extent of deletion alleles within the locus. FIG. 12(B) illustrates the predicted PBO-4 protein domains. The predicted protein consists of a signal peptide, 12 transmembrane domain, a re-entrant loop between transmembrane domains 9 and 10 and an intracellular carboxy-terminal tail that contains a predicted calmodulin binding site.
FIG. 13 shows a sequence alignment of PBO-4 to human Na + /H + exchangers. Deduced polypeptide sequence of PBO-4 aligned with human NHE1(P19634), NHE2(Q9UBY0) and NHE3(P48764) are shown. Sequences were aligned with ClustalX tities are shaded and the arrowhead indicates the predicted signal peptide cleavage site. The last translated amino acid of each pbo-4 mutant allele is denoted by a star. The black bars indicate predicted transmembrane domains, and the dotted line denotes the re-entrant loop as determined for NHE1. The boxed sequence indicates the predicted calmodulin binding domain. The positions of the GFP insertions are indicated by triangles.
DETAILED DESCRIPTION
As used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural reference unless the context clearly dictates otherwise. For example, reference to “a host cell” includes a plurality of such host cells.
As used herein a “Substantially Identical” polypeptide sequence means an amino acid sequence which differs from a reference sequence only by conservative amino acid substitutions, for example, substitution of one amino acid for another of the same class (for example, valine for glycine, arginine for lysine, etc.) or by one or more non-conservative substitutions, deletions, or insertions located at positions of the amino acid sequence which do not destroy the function of the polypeptide (assayed, for example, as described herein). Preferably, such a sequence is at least 80-100%, more preferably at least 85%, and most preferably at least 90% substantially identical at the amino acid level to the sequence used for comparison.
To identify the nature of the signal, source, and target, screens for mutations affecting the defecation cycle and in particular, mutations specifically affecting the posterior body contraction have been performed. From these screens, only three genes, pbo-1, pbo-4 and pbo-5 result in a specific loss of posterior body contraction, without affecting any other aspect of the defecation motor program. The pbo-1 gene has not been cloned. The pbo-4 gene encodes a putative Na + /H + exchanger and is required for activation of the posterior body contraction (P. Dal Santo, personal communication; see Discussion). Its expression in the posterior intestine suggests that pbo-4 functions as a mediator between the calcium signal of the clock in the intestine and the muscle receptor that stimulates the posterior body contraction.
Na + /H + exchangers have been implicated in numerous physiological processes such as intracellular pH homeostastis, cell volume regulation, and reabsorption of NaCl across epithelial cells. However, the proton can be involved in more complex cellular processes other than intracellular pH regulation. Deletion of genes involved in H + secretion and reception results in a broad range of cellular and behavioral phenotypes. Significantly, deletion of the murine NHE1 gene reveals it is required for functions as diverse as pH homeostasis to cell morphology and adhesion. Consistent with a broader role for protons as intercellular messengers, a large family of proton-gated channels, termed the acid-sensing ion channels (ASICs), have been identified. Knockouts of specific ASIC family members have demonstrated that proper H + signaling is required not only for sensory modalities such as nociception and mechanoreception, but also for synaptic plasticity and learning and memory in the brain. While specific H + -gated receptors such as ASIC1 are expressed in hippocampal neurons, the source of protons required to activate these receptors remains a mystery. Hence, the present invention is useful in the field of medicine and provides valuable research tools for the identification of medical and veterinary compounds.
The gene pbo-5 gene encodes a novel H + -gated ion channel subunit. When expressed in Xenopus oocytes , PBO-5 co-assembles with the PBO-8 subunit to form a functional H + -gated nonselective cation channel. PBO-5 and PBO-8 are expressed in the posterior body wall muscles, suggesting these two subunits are localized to the appropriate tissues to mediate posterior body contraction. The channel encoded by PBO-5/8 is an inwardly-rectifying non selective cation channel. The molecular identification of the PBO-5 and PBO-8 receptor subunits defines a unique class of the cys-loop ligand-gated ion channel superfamily, and demonstrates a non-neuronal signaling mechanism. Furthermore, the functional characterization of H + -sensitivity demonstrates that the PBO-5/8 signaling pathway defines a novel mechanism of cellular communication that relies on H + as a physiological transmitter.
Methods
Molecular Characterization of pbo-5 and pbo-8
The sequence of the pbo-5 transcript was determined by reverse transcription of wild-type RNA followed by PCR amplification (RT-PCR) and direct sequencing. The 5′ trans-spliced sequence was obtained by PCR amplification using an SL1 primer and a nested, gene specific primer in the second exon. The 3′ sequence was obtained by PCR amplification with nested primers in the third predicted exons and with an oligo-dT primer. PCR products were cloned into the pCR2.1 TA cloning vector (Invitrogen) and a full length clone pPD68 was generated.
PBO-8 cDNAs were isolated by RT-PCR. We determined the 5′ end of the gene by circular RACE (Maruyama et al., 1995). The 3′ end of the gene was based on computer prediction and sequence similarity to PBO-5. To isolate full-length cDNAs, oligonucleotide primers were designed to the 5′ and 3′ untranslated regions of pbo-8. PCR products were cloned into pCR2.1, and subsequent products were sequenced to generate a full-length error free PBO-8 cDNA.
Electrophysiology of PBO-5 and PBO-8
To generate plasmid constructs for Xenopus oocyte expression, the foil length error-free cDNA was subcloned into the pSGEM expression vector (courtesy M. Hollmann). The pbo-5 expression vector was constructed by cutting the pPD70 plasmid with restriction enzymes SacII and Eag1, then using T4 DNA polymerase to blunt the ends. Cut products were gel purified (Qiagen) and re-ligated using T4 DNA ligase (Promega) to create the plasmid pAB20. The PBO-8 expression construct was made by cutting a previously sequenced error-free cDNA (M. Peter, unpublished). The cDNA was first cloned into the pSGEM expression vector. Next, the restriction enzymes SacII and BsaBI were used to cut the plasmid, and the ends were blunted with T4 DNA polymerase. Cut products were gel purified and re-ligated to produce pAB21.
Capped RNA was prepared using the T7 mMessage mMachine kit (Ambion). Xenopus oocytes were collected and coinjected with 25 ng each of PBO-5 and PBO-8 cRNA and two-electrode voltage clamp recordings were performed 3-5 days post-injection. The standard bath solution for dose-response and control I-V experiments was Ringer's (in mM): 115 NaCl, 1.8 BaCl2, 10 Bis-Tris Propane (pH 7.4 Acetic acid). For dose-response experiments, each oocyte was subjected to a 5 second application of test pH (7.0-5.0) with 2 minutes of pH 7.4 wash between test applications.
Ion selectivity experiments: All points are responses to test pulse applications of pH 6.8 for 5 seconds. The reversal potential of PBO-5/PBO-8 expressing oocytes were first determined in standard Ringer's (in mM): 115 NaCl, 1.0 CaCl2, 10 Bis-Tris Propane (pH 7.4, acetic acid). For chloride permeability a simplified solution was used, chloride-free (in mM): 115 Na + gluconate, 1.0 CaCl 2 , 10 Bis-Tris Propane (pH 7.4 acetic acid). For Na + permeability a simplified solution was used, Na + free (in mM): 115 mM N-methyl D-glucamine (NMDG), 1.8 CaCl 2 , 10 Bis-Tris Propane (pH 7.4 acetic acid)). All solutions were brought to pH by addition of NaOH or acetic acid. To determine K + permeability, I-V experiments were performed in K + Ringer's (in mM): 115 K + -gluconate, 1.0 CaCl 2 , 10 Bis-Tris Propane (pH=7.4 acetic acid). To determine Ca 2+ permeability extracellular Na + was lowered to 90 mM and extracellular CaCl 2 was increased to 3 mM and 10 mM, compare to 1 mM Ca 2+ control. To better resolve calcium permeability, the Na + free solution was used except CaCl 2 was increased ten-fold, 18 mM CaCl2 (in mM): 115 NMDG, 18 CaCl 2 , 10 Bis-Tris Propane, (pH 7.4 acetic acid). Osmolarity was measured for each solution and was maintained at 240 mOsm by the addition of sucrose. All recordings were done at room temperature. We used 3M KCl filled electrodes with a resistance between 1-3 MΩ. We used a 3M KCl agar bridge to minimize liquid junction potentials, and all liquid junctions potentials arising at the tip of the recording electrode were corrected online.
Data analysis. Data acquisition and analysis were performed using Axograph (Axon Instruments) software, and curve fitting and statistical analysis were performed with Prism (Graphpad). Dose-response curves from individual oocytes were normalized to the maximum and minimum values and averaged for at least eleven oocytes. Normalized data were fit to the four-parameter equation derived from the Hill equation: Y=Min+(Max−Min)/(1+10(LogEC50−X)(nH)), where Max is the maximal response, Min is the response at the lowest drug concentration, X is the logarithm of agonist concentration, EC50 is the half-maximal response, and nH is the Hill coefficient. Error bars represent the standard error of the mean.
Reversal potential values represent averaged linear regression measurements of individual experiments above and below the point of X-axis intersection. Because the PBO-5/PBO-8 receptor exhibits rectification we used linear regression from −15 to +15, where the relationship is most linear, to determine the reversal potential. Error bars represent the standard error of the mean.
Results
pbo-5 Behavioral Analysis
Recessive alleles in the pbo-5 gene result in a strong posterior body contraction defective (Pbo) phenotype. The posterior body contraction is completely absent from these mutants while the other aspects of defecation such as anterior body contraction, enteric muscle contraction, and cycle timing remain unaffected. Other behaviors including locomotion, egg laying, feeding and mating are also normal.
In contrast to the recessive pbo-5 alleles, two dominant mutations, n2331 and ox7, result in a distinctive hypercontracted phenotype known as posterior body cramp. Specifically, when the defecation cycle is initiated in these mutants, the posterior body muscles contract but fail to immediately relax, and the enteric muscle contraction occurs while the posterior body wall muscles are still contracted. As the animals move, the posterior body muscles eventually relax and the next cycle can be observed.
pbo-5 Cloning
The pbo-5 gene was mapped to the right arm of chromosome V and cloned ( FIG. 2 ). The Y44AE predicted open reading frame encodes pbo-5, confirmed by mutant allele sequencing (Table 1). Furthermore, a mini-gene construct containing the pbo-5 cDNA fused to 4.4 kb of sequences upstream of the second exon rescues the phenotype of pbo-5(ox24) mutants.
TABLE 1 pbo-5 mutations
pbo-5 Encodes a Ligand-Gated Ion Channel
The primary structure of the pbo-5 cDNA was determined by reverse transcription and polymerase chain reaction. The pbo-5 cDNA includes an SL1 trans-spliced leader sequence at the 5′ end and a total of 9 exons spanning a 7 kb genomic region ( FIG. 2 ). The pbo-5 mutations fall into four categories: (1) nine deletions (2) three nonsense (3) seven missense, and (4) one splice junction mutation (Table 1). The predicted pbo-5 cDNA encodes a 499 amino acid protein ( FIG. 3 ).
BLAST and protein motif queries of PBO-5 suggest that it is a member of the ligand-gated ion channel superfamily. Ligand-gated ion channels are oligomeric receptor complexes containing an integral ion channel that is opened upon ligand binding (Betz, 1990). Ion channels that are gated by acetylcholine, serotonin, γ-aminobutyric acid, and glycine are a superfamily of homologous neurotransmitter receptors, termed the cys-loop superfamily. Although over 100 ligand-gated ion channel subunits have been identified in numerous organisms, each subunit can be assigned to one of the four receptor families based on sequence similarity, and/or functional activity. All ligand-gated ion channel subunits share a common structural and functional homology and have a high degree of amino acid similarity. The subunits are demarcated by a signal peptide, an extracellular amino-terminus that contains consensus ligand binding sites and an invariant disulfide bonded loop (cys-loop), four transmembrane domains (M1-M4), a large cytoplasmic loop between M3-M4, and a short extracellular carboxy terminus (Karlin and Akabas, 1995; Ortells and Lunt, 1995) ( FIG. 2 ). Electron microscopy, electrophysiological and structural data suggest that ligand-gated ion channels are formed from five homologous subunits that are pseudo-symmetrically arranged around a central ion channel, such that the M2 domain lines the ion-channel wall and determines ion selectivity (Betz, 1990; Brejc et al., 2001; Unwin, 1993).
Hydropathy plots and alignment of PBO-5 with various ligand-gated ion channel subunits demonstrates that PBO-5 contains the hallmarks of ligand-gated ion channels ( FIG. 3 ). Additionally, PBO-5 contains many residues that underpin the conserved secondary structure of the cys-loop ligand-gated ion channel superfamily (Brejc et al., 2001). BLAST searches of PBO-5 against human, mouse, Drosophila , and C. elegans genomes suggest that PBO-5 most closely resembles cholinergic receptors. However, phylogenetic analysis demonstrates that PBO-5, and related orthologs, represents a divergent subunit that cannot be categorized into one of the four families based on sequence similarity ( FIG. 4 ). BLAST searches against the C. elegans genome revealed another predicted protein, PBO-8, which contained high sequence identity to PBO-5. For example, accession numbers P12389, 008952 and Q7T2T8. Based on sequence similarity and residues known to be involved with specific ligand sensitivity, the ligand for the PBO-5 receptor was not clearly identifiable from the native sequence. Further, mutants that are defective in GABA, acetylcholine, serotonin, and peptidergic neurotransmission do not exhibit posterior body contraction defects. Therefore, it seemed unlikely that PBO-5 would be activated by known classical neurotransmitters.
pbo-5 is Expressed in the Posterior Body Wall Muscles
If PBO-5 is the receptor that mediates posterior body contraction then it should be expressed in the body wall muscles. To determine the cellular expression of pbo-5, a transcriptional pbo-5::gfp fusion gene was constructed that contained 3.8 kb upstream sequence of the translational start codon fused to the GFP open reading frame (Chalfie et al., 1994). Stable chromosomally integrated lines of this construct expressed GFP in the most posterior muscle cells of the tail and in a small number of neurons in the head ( FIG. 5 ). The expression pattern of PBO-5 demonstrates that it is expressed in the appropriate cells to mediate posterior body contraction.
PBO-5 is not Activated by Classical Neurotransmitters
To determine if PBO-5 can form a homo-oligomeric receptor, we injected PBO-5 cRNA in Xenopus oocytes . Since sequence information did not confidently predict the ligand that would activate the putative PBO-5 receptor, a candidate approach was undertaken to ascertain the ligand. Two-electrode voltage clamp recordings were used to assay receptor functionality. A host of classical neurotransmitters such as acetylcholine, choline, GABA, glycine and serotonin were applied to PBO-5 injected oocytes, yet all ligands failed to elicit a functional response.
Typically, muscle type acetylcholine receptors require both α and non-α subunits to form functional receptors. The predicted PBO-8 protein is the most closely related to PBO-5 of all predicted cholinergic-like receptors in C. elegans ( FIG. 4 ).
PBO-8 Primary Structure and Expression
The pbo-8 predicted open reading frame encodes a protein that is homologous to ligand-gated ion channels ( FIG. 3 ). Significantly, the PBO-8 protein most closely resembles PBO-5 ( FIG. 4 ). To determine the primary structure of PBO-8 RT-PCR was performed and full-length cDNA clones isolated. The PBO-8 full-length cDNA consists of 13 exons that span 4.1 kb of genomic DNA ( FIG. 6A ). The PBO-8 cDNA encodes a 423 amino acid protein ( FIG. 6A ). We performed protein alignments with PBO-8 and PBO-5 revealing they share 35% identity. With the exception of one conservative amino acid change, the residues in the M2 domain are identical ( FIG. 3 ). If PBO-8 oligomerizes with PBO-5 to form a functional receptor, then PBO-8 should have overlapping expression with PBO-5. To address the expression pattern of PBO-8, a transcriptional fusion containing 4 kb of upstream promoter sequence fused to GFP was constructed. GFP expression was observed in the most posterior body wall muscles in the tail, identical to PBO-5 expression ( FIG. 6B ). These data suggest that PBO-8 may oligomerize with PBO-5 to form a functional receptor.
PBO-5 /PBO-8 Forms a if-Gated Ion Channel
To determine if PBO-5 and PBO-8 can co-assemble to form a functional receptor, we injected PBO-5 and PBO-8 cRNA into Xenopus oocytes . Agonists which function at other ligand-gated ion channels (such as, ACh, GABA, glycine, 5-HT, glutamate, and choline) lacked the ability to activate PBO-5 homomers, PBO-8 homomers or PBO-5/PBO-8 heteromers. Activation of receptors was not unexpected because genetic evidence demonstrates acetylcholine, GABA, glutamate and serotonin are not required for posterior body contraction. To determine the possible signal that mediates posterior body contraction we examined the pbo-4 gene.
The predicted pbo-4 gene encodes a protein related to Na + /H + exchangers. PBO-4 is expressed in the posterior intestine and is required for posterior body contraction. Na + /H + exchangers mediate the exchange of one Na + into the cell for one H + out of the cell. The expression of PBO-4 in the posterior intestine parallels the expression pattern of PBO-5 and PBO-8 in the posterior body wall muscles. These data suggest that PBO-4 mediates the secretion of H + from the intestine, into the pseudocoelomic space, adjacent to PBO-5/PBO-8 posterior muscle expression. Therefore, without wishing to be bound by theory, we hypothesized that H + ions may activate or may be required for co-activation of PBO-5/PBO-8 receptors.
To determine if H + ions are sufficient to activate PBO-5/PBO-8 receptors, we applied test pulses of varying pH to PBO-5/PBO-8 expressing cells. Test pulses of pH 6.8 evoked robust inward currents, indicating that H + ions are sufficient to activate recombinant receptors ( FIG. 7 , inset). To demonstrate that current responses evoked by changes in pH were not due to endogenous channels or transporters, we applied maximal test pulses of pH 5.0 to water injected and uninjected oocytes. Only oocytes injected with PBO-5/PBO-8 cRNA exhibited H + -gated responses. To determine if PBO-5 and PBO-8 can form functional homomeric H + -gated ion channels, we injected each subunit alone into oocytes. Injection of PBO-5 or PBO-8 cRNA into oocytes, resulted in little or no functional expression compared to oocytes co-injected with PBO-5 and PBO-8 cRNA. These data suggest that the PBO-5/PBO-8 heteromultirnerization is required for efficient functional receptor expression in vitro.
H + ions have been demonstrated to modulate classical synaptic transmission. For example, acidic changes in pH inhibit acetylcholine receptor function, where alkaline environments enhance receptor function (Palma et al., 1991; Pasternack et al., 1992). To determine whether or not classical neurotransmitters co-activate PBO-5/PBO-8 receptors, we applied pH 6.8 with and without 1 mM ligand. Application of pH 6.8 plus acetylcholine, choline or GABA was not significantly different from pH 6.8 only application (data not shown). Taken together, these data suggest that H + ions alone are sufficient to fully activate PBO-5/PBO-8 receptors.
To determine the pH 50 (half-maximal activation) of PBO-5/PBO-8 heteromultimers, we first identified the pH range at which the recombinant receptors were activated. We determined that the PHIO (10% maximal activation) was approximately pH 7.0. We set our perfusion buffer at pH 7.4 for all experiments, where no activation of recombinant receptors was observed. A pH 50 =6.83±0.01 was determined by applying decreasing pH test pulses (pH 7.0-5.0). A steep Hill coefficient of 9±0.66 was determined, demonstrating PBO-5/PBO-8 receptors exhibit significant H + binding cooperativity ( FIG. 7 ).
PBO-5/PBO-8 Ion-Selectivity
Current-voltage (I-V) analysis was used to characterize the ionic conductance underlying PBO-5/PBO-8 responses. The H-gated current had a reversal potential of 10.18±0.80 mV in Ringer's solution ( FIG. 8A ). The I-V relationship demonstrates that PBO-5/PBO-8 exhibits inward rectification ( FIG. 8A , inset). The positive reversal potential suggests that PBO-5/PBO-8 encodes a cation-selective ion channel. To determine if Na + underlies PBO-5/PBO-8 H + -evoked responses, we replaced Na + with the large cation N-methyl D-glucamine. In Na + -free solution, the inward current was eliminated and the reversal potential was −82.90±8.13 mV ( FIG. 8B ). Furthermore, to demonstrate anions such as Cl − do not flow through PBO-5/PBO-8 channels, we replaced extracellular Cl − with the impermeable anion gluconate. In C − free solution, the inward current remained with no significant shift in reversal potential (ΔE rev =0.25 mV, P>0.05, two-way ANOVA), compared to control ( FIG. 8C ). This demonstrates Na + is the primary charge carrier through PBO-5/PBO-8 channels.
To determine the cation-selectivity of the PBO-5/PBO-8 ion channel, we substituted extracellular Na + with equivalent K + . In K + Ringer's solution, I-V relationships were not significantly different (P>0.05 two-way ANOVA) compared to Na + Ringers control ( FIG. 8D ). Additionally, strong inward rectification was present in I-Vs determined in K + Ringers, demonstrating rectification was not due to ion-selectivity. Taken together, these data demonstrate PBO-5/PBO-8 encodes a non-selective inwardly rectifying cation channel.
Next, Ca 2+ permeability of the PBO-5/PBO-8 ion channels was assayed. The I-V relationships under three Ca 2+ concentrations: 1 mm control, 3 mM, and 10 mM, were determined. Increasing calcium to 10 mM resulted in a positive shift in reversal potential from control ( FIG. 9A ). To better resolve calcium permeability, NaCl was replaced with NMDG in the extracellular solution, making Ca 2+ the only relevant extracellular ion. Increasing Ca 2+ in this solution revealed that PBO-5/PBO-8 channels are calcium permeable. Increasing Ca 2+ 10 fold caused a +50 mV shift in reversal potential compared to control ( FIG. 9B ).
Interestingly, H + -evoked inward currents were significantly reduced as extracellular Ca 2+ was increased ( FIG. 9 ). Specifically, a control pulse of pH 6.8 with 1.0 mM Ca 2+ evoked a large response, and an equivalent test pulse of pH 6.8 with 10.0 mM Ca 2+ evoked a much smaller response. This suggests that, while Ca 2+ is permeable, high amounts of Ca 2+ inhibit gating of PBO-5/PBO-8 channels.
To further investigate the Ca 2+ inhibition of PBO-5/PBO-8 receptors, dose response experiments were performed under different extracellular Ca 2+ conditions (0.1, 1, 3, 10 mM). PBO-5/PBO-8 receptors under 1 mM Ca 2+ control conditions exhibited a pH 50 =6.88 and a Hill coefficient of 6 ( FIG. 10A ). As Ca 2+ was increased to 10 mM a right shift in the activation curve of PBO-5/PBO-8 was observed. Specifically, a significantly different pH 50 =6.59 and a Hill coefficient of 4 was determined under 10 mM Ca 2+ test conditions ( FIG. 10A ). These data demonstrate that as extracellular Ca 2+ is increased, H + sensitivity and cooperativity decreases.
Next, to determine if increasing extracellular Ca 2+ caused an inhibition of maximal PBO-5/PBO-8 activation, Ca 2+ conditions at three different pH ranges (7.0, 6.8, and 6.0) were applied. H-evoked responses were significantly reduced, compared to 1 mM Ca 2+ control, at pH 7.0 and 6.8 as Ca 2+ was increased to 3 mM and 10 mM ( FIG. 10B ). However, at pH 6.0, increasing extracellular Ca 2+ had no effect on maximal activation of PBO-5/PBO-8 ( FIG. 10B ). These data suggest that Ca 2+ acts as a competitive antagonist at PBO-5/PBO-8 receptors. We are further examining the mechanism of Ca 2+ antagonism to PBO-5/PBO-8 receptors.
Discussion
It is demonstrated that pbo-5 encodes a novel ligand-gated ion channel subunit required to initiate the posterior body contraction of the defecation cycle. Loss of pbo-5 activity specifically eliminates the posterior body contraction, while gain-of function alleles result in hypercontraction of the posterior body muscles. PBO-5 is expressed in the most posterior muscle cells of the tail, suggesting it is properly localized to mediate the posterior body contraction. Finally, it is demonstrated that PBO-5 heteromultimerizes with PBO-8 to form a novel H + -gated ion channel when expressed in Xenopus oocytes . The channel encoded by PBO-5/PBO-8 is a nonselective inward rectifying cation channel. The molecular identification and functional characterization of the PBO-5 and PBO-8 receptor subunits defines a novel group of the cys-loop ligand-gated ion channel superfamily. Furthermore, the functional characterization of H + -sensitivity demonstrates that the PBO-5/PBO-8 signaling pathway defines a novel mechanism of cellular communication.
H + Dependence of PBO-5/PBO-8
The overlapping cellular expression of PBO-5 and PBO-8 in the most posterior body muscles of that tail, coupled with the fact that functional receptor expression is only observed when both PBO-5 and PBO-8 are coinjected into oocytes, strongly suggests the PBO-5/PBO-8 represents the native receptor that mediates posterior body contraction. We have demonstrated that H + ions are sufficient to activate PBO-5/PBO-8 receptors.
The defecation cycle in a wild-type animal occurs every 50 seconds with little variability and the first muscle contraction to occur is the posterior body contraction. It has been demonstrated that periodic calcium release in the intestine correlates with the onset of the posterior body contraction (Dal Santo et al., 1999). The itr-1 gene which encodes an inositol triphosphate (IP 3 ) receptor is required in the intestine for proper defecation cycle timing (Dal Santo et al., 1999). Hypomorphic itr-1 alleles exhibit long or no defecation cycle cycles (>50 seconds), while overexpression of itr-1 results in short defecation cycle times (<50 seconds). Furthermore, calcium imaging of itr-1 hypomorphic alleles that have no defecation cycles (i.e., no posterior body contraction) fail to exhibit calcium oscillations (Dal Santo et al., 1999). Taken together, these data suggest that IP 3 receptor activity in the intestine is required for the signaling of each muscle contraction in the defecation cycle.
The posterior body contraction is the initial contraction in the defecation motor program, and does not rely on neuronal input. The PBO-5/PBO-8 receptor is gated by H + ions, and PBO-5 is required for posterior body contraction. It has been demonstrated that IP 3 receptor (itr-1) mediated calcium signaling in the intestine is required for the activation of the posterior body contraction (Dal Santo et al., 1999). However, the nature of the signal was unknown as mutants with defects in classical neurotransmission have normal posterior body contraction.
The pbo-4 gene encodes a protein that has similarity to Na + /H + exchangers (NHEs). pbo-4 mutants are phenotypically identical to pbo-5 mutants, and the pbo-4; pbo-5 double mutant is identical to both single mutants. This suggests that pbo-4 and pbo-5 are in the same signaling pathway that mediates posterior body contraction.
Furthermore, the expression pattern of pbo-4 is restricted to the posterior intestine, adjacent to the muscle expression of PBO-5 and PBO-8. Na + /H + exchangers have been implicated in a number of processes including intracellular pH and cell volume regulation, and in reabsorption of NaCl across epithelial cells (Counillon and Pouyssegur, 2000; Orlowski and Grinstein, 1997). Plasma membrane NHEs mediate the electroneutral exchange of Na + ions into the cell for H + ions out, thereby acidifying the extracellular environment while increasing intracellular pH. Mammalian NHEs are regulated by a number of factors including phosphorylation, calcium, and by interactions with accessory proteins (Orlowski and Grinstein, 1997). For example, mammalian NHE1 is sensitive to increases in cytosolic Ca + , due to a high-affinity calmodulin binding site present on the C-terminal tail of the protein (Bertrand et al., 1994). Deletion of this binding site causes NHE1 to be constitutively active (Wakabayashi et al., 1994; Wakabayashi et al., 1997). Therefore, under normal conditions (low Ca 2+ ), the calmodulin-binding site is unoccupied and exerts an inhibitory effect. An intracellular rise in Ca 2+ stimulates Ca 2+ /calmodulin binding to NHE1, thereby releasing inhibition, and activating Na + /H + exchange. Analysis of the C-terminal tail of the PBO-4 protein predicts a putative calmodulin binding site as well as a consensus phosphorylation site for CaMKII.
The structural analysis and expression of pbo-4 in the intestine predicts that PBO-4 mediates the exchange of Na + ions into the intestine for H + ions out of the intestine into the pseudocoelomic space. H + binding has been demonstrated herein to be sufficient to activate PBO-5/PBO-8 receptors. Therefore, without wishing to be bound by theory, it is believed that the H + signal arises from the intestine and H + transport is mediated by PBO-4.
It has been demonstrated that IP 3 receptor mediated release of calcium from the intestine correlates with the onset of the posterior body contraction and is required. Therefore, it is believed that a necessary feature of the posterior body contraction signaling mechanism is that it be modulated by calcium. The pbo-4 gene, expressed in the posterior intestine, encodes a Na + /H + exchanger with a predicted Ca 2+ /calmodulin binding domain. It has now been demonstrated that H + ions are sufficient to activate PBO-5/PBO-8 receptors (e.g., using Xenopus oocytes (in vitro)) that are localized to the posterior body muscles.
Without wishing to be bound by theory, from this data it is proposed that for posterior body contraction: 1) IP 3 receptors localized to the smooth endoplasmic reticulum in the intestine are activated every 50 seconds. Activation results in the intracellular rise of Ca 2+ in the intestine; 2) Ca 2+ binds to the C-terminal calmodulin-binding domain of PBO-4, thereby activating H + transport activity; 3) PBO-4 transports H + ions out of the intestine acidifying the pseudocoelomic space; and 4) H + ions bind and activate the PBO-5/PBO-8 receptors expressed in posterior body wall muscle, thereby allowing Na + influx into the cell causing a depolarization and subsequent muscle contraction ( FIG. 11 ).
This simple model can account for the non-neuronal nature of the posterior body contraction, and involves strict calcium regulation. The present invention demonstrates that PBO-5/PBO-8 receptors are exquisitely sensitive to changes in extracellular pH, as determined in heterologous cells (pH 50 =6.83±0.01). The sensitivity of PBO-5/PBO-8 receptors suggests minor acidification of the pseudocoelomic space is required to activate the posterior body contraction. The pseudocoelomic space separates the intestine from the muscle, and is relatively small as observed in electron micrographs. Thus, the acidification of the pseudocoelomic space at the posterior end of the animal to a pH ˜6.8 is not physiologically unreasonable. In vivo recording from the posterior body wall muscles is preformed to recapitulate the in vitro findings.
PBO-5/PBO-8 is a Novel Cys-Loop Ligand-Gated Ion Channel
The PBO-5 and PBO-8 subunits display the structural motifs common to the superfamily of cys-loop ligand-gated ion channels. However, the distinctive sequence and functional activity prevent classification within any of the four established receptor families. Motor behaviors, such as muscle contraction, are typically controlled via fast synaptic transmission between a motor neuron and muscle cell. The present invention demonstrates that H + ions alone are sufficient to activate recombinant receptors and that co-application of other classical neurotransmitters has little effect on activation. Furthermore, the functional characterization of the receptor and proposed model of excitation provide a unique form of fast non-synaptic communication. Protons have been demonstrated to be modulatory at “cys-loop” ligand-gated ion channels; however, this is the first evidence that protons can directly activate this receptor subclass. Therefore, the present invention demonstrates that H + fulfills the criteria of a fast transmitter in C. elegans.
In one exemplary embodiment mammalian paralogs and/or orthologs are identified, for example by BLAST searches using PBO-5 and PBO-8 sequences (e.g. SEQ ID NOS: 6 and 7), and one or more of the paralogs and/or orthologs is confirmed to be a component of a H + -gated ion channel. In particular, there are a number of predicted cholinergic-like proteins to which PBO-5 and PBO-8 share identity. Changes in extracellular pH have been demonstrated to regulate ion channel function, hi most cases, H + ions modulate classical neurotransmission by inhibiting or exciting various classical ligand-gated ion channels. While it has been demonstrated that H + signaling is a major pathway for pain sensation through the acid-sensing ion channels (ASIC), direct H + signaling has never been associated with cys-loop ligand-gated ion channels (Waldmann et al., 1997; Waldmann et al., 1999).
Recently, a novel Zn 2+ activated ligand-gated ion channel (ZAC) has been cloned and characterized in humans (Davies et al., 2003). The ZAC channel represents a distinct class of cys-loop ligand-gated ion channels that is not activated by classical neurotransmitters. Interestingly, the ZAC subunit has been retained in some mammals (human and dog), but has been lost by others (mouse and rat), demonstrating specific cell signaling mechanisms may vary across species. Therefore, an exemplary embodiment of the invention provides a method for the identification and characterization of the H + gated PBO-5/PBO-8 receptor in other species.
In an exemplary embodiment, the pharmacology of the PBO-5/PBO-8 receptor is determined, in another exemplary embodiment modulation of PBO-4 by Ca 2+ is determined. In yet another exemplary embodiment, isolation of PBO-8 mutants is performed and the mutant phenotype assayed relative to PBO-5 and/or PBO-4. Optionally, genetic analysis is conducted to determine if PBO-8 is in the same genetic pathway as PBO-5 and/or PBO-4.
To determine if H + ions are required to initiate a posterior body contraction endogenous acidification of the pseudocoelomic space is blocked. For example, 100 mM Bis-Tris Propane buffered saline (pH 7.2) is injected into the pseudocoelomic space of an animal and defecation cycles postinjection observed. It is believed that animals that have had buffered saline injected into the pseudocoelomic space will fail to initiate a posterior body contraction while all other steps of the defecation cycle will be normal. The injected animals should phenocopy both pbo-4 and pbo-5 mutants.
Alternatively, a caged buffer is used to assay the requirement for H + activation of PBO-5/PBO-8 receptors in vivo. For example, animals are injected with a caged buffer (Molecular Probes) and the buffer uncaged, by flash photolysis, as a posterior body contraction is about to occur. An advantage of the latter scheme is that an animal can be injected first and then observed for a number of cycles to determine if it retains normal defecation cycles, and in particular posterior body contractions. After quantification of a number of defecation cycles, the buffer is uncaged and the animal observed for a specific loss of posterior body contraction. Li addition, the inverse experiment, where caged protons are injected, may be conducted to elicit an out of phase posterior body contraction by uncaging the protons during the intercycle.
Functional Analysis of Dominant pbo-5 Alleles
Several of the pbo-5 mutations provide particularly interesting insights into the structure and function of the PBO-5 protein. Loss-of-function mutations cause an absence of posterior body contraction, while gain-of-function mutations cause hypercontraction. Two dominant alleles (n2331 and ox7) result in the same mutation within the M2 domain of the ion channel. Specifically, residue 316 is mutated from leucine to phenylalanine (L316F). The M2 domain lines the ion channel wall, and residues in and around M2 affect ion selectivity and receptor desensitization (Leonard et al., 1988). An adjacent residue is altered in the M2 domain of the cholinergic DEG-3 gain-of-function mutant, and causes cell death (Treinin and Chalfie, 1995). It was proposed that prolonged opening and increased ion flow through DEG-3 ion channels underlies the degeneration. Similarly, dominant gain-of-function mutations within the M2 domain of acetylcholine receptors leads to increased ion flow through slower channel closure (Engel et al., 1996). Therefore, it is believed that the cramp phenotype observed in the dominant alleles is due to a channel that has slower inactivation. To determine if pbo-5 (n2331dm) encodes a slowly inactivating receptor, cDNAs that carry the mutation are isolated and pbo-5 (n2331dm) cRNA is coexpressed with wild-20 type PBO-8, and receptor function is assayed. It is believed that pbo-5 (n2331dm) will result in a response to acidic pH application that is prolonged and enduring, rather than desensitizing as in the wild-type.
PBO-5/PBO-8 Pharmacology
PBO-5/PBO-8 forms a heteromultimeric H + -gated cation channel and extracellular Ca 2+ concentration affects PBO-5/PBO-8 pH sensitivity. The PBO-5/PBO-8 receptor subunits are structurally related to the ligand-gated ion channel superfamily, and sequence analysis and functional activity place the PBO-5/PBO-8 receptor into a previously unknown family ( FIG. 4 ). hi an exemplary embodiment, H + -gated cation channel receptors are identified and assayed for sensitivity to known ligand-gated ion channel agonists and antagonist. In addition, H + -gated cation channel receptors are identified in a subject, for example, a mammalian or vertebrate subject, such as a human, and assayed for functions described herein. Such mammalian, or vertebrate, receptors are assayed for drug interactions with have agonist, antagonist or blocking activity.
For example, it was observed during electrophysiological investigation of PBO-5/PBO-8 that the buffer HEPES (N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid) in our extracellular solution produced a very rapid rundown of the H + -evoked current that could not be explained by poor oocyte health. An initial pulse of pH 6.8 HEPES buffered solution gave a robust inward current. However, subsequent application of pH 6.8 HEPES caused a marked reduction in inward current. Eventually, PBO-/PBO-8 receptors could be run-down to zero current with repeated pH 6.8 applications that was not reversible with time or supramaximal pH 5.0 application. Initially an extracellular ion replacement was conducted, since a divalent ion such as Ca 2+ could impart the current block. However, Ca 2+ reduced solutions still exhibited use-dependent block, therefore, the buffer containing HEPES was substituted with Bis-Tris Propane (1,3-Bis[tris(hydroxymethyl)methylamino) propane or MES (2-(N-Morpholino)-ethanesulfonic acid.
When HEPES was replaced with either Bis-Tris Propane or MES, repeated acidic pH test pulses did not cause current run-down. Therefore, HEPES was shown to be inhibitory to the receptor. Furthermore, HEPES was demonstrated to be the relevant blocking molecule by applying pH 6.8 pulses of HEPES buffered solution until the evoked current was run down to zero. Following pulsed run down, a pH 6.8 pulse of Bis-Tris propane was applied to the run down receptors. Application of pH 6.8 Bis-Tris Propane or MES buffered solutions to rundown receptors, evoked a robust inward current. Specifically, a current equal to or greater than the initial pH 6.8 HEPES response was obtained.
How can HEPES be inhibiting the channel? Recently, the structure of an acetylcholine binding protein (AChBP) that is homologous to the N-terminus of acetylcholine receptors has been resolved (Brejc et al, 2001). The structure of this protein agrees with the predicted N-terminal structure of ligand-gated ion channels. Importantly, it was determined that the ligand binding sites are located at each of the five subunit interfaces, which are located in the extracellular N-terminal part of the protein. Interestingly, the resolved crystal structure contained a HEPES molecule present in each ligand-binding site. In the structure it was determined that HEPES made no specific hydrogen bond with the protein, but its quaternary ammonium group stacked onto Trp143 making cation-it interactions (Brejc et al., 2001). These data suggest that the HEPES molecule may be occluding the H + -binding site of PBO-5/PBO-8 receptors. In an exemplary embodiment, mutations are made in and around the presumptive ligand-binding pocket and assayed for abolishment of HEPES inhibition.
As the PBO-5/8 receptor is exclusively activated by H + , it was next determined if PBO-5/8 gating could be blocked with amiloride. Amiloride is a commonly used pharmacological agent used to block acid sensing ion channels (ASIC). Application of 1 mm amiloride to PBO-5/8 expressing cells did not result current block, demonstrating the H-gating mechanism of PBO-5/8 receptors is different from the ASIC channels. Furthermore, common cholinergic antagonist such as d-tubocurare were applied to PBO-5/8 expressing cells, but all attempts to pharmacologically block PBO-5/8 responses failed. These data suggest the gating mechanism of PBO-5/8 receptors is quite different from both cholinergic and ASIC receptors.
In an exemplary embodiment, other compounds which bind the ligand binding pocket, for example, of a vertebrate H + -gated channel, which may be identified by the methods of the present invention, are assayed. In one exemplary embodiment, agonists and/or antagonists are identified. In another exemplary embodiment, an agonist and/or antagonist is manufactured as a medicament for the treatment of conditions relating to activation or inactivation of the H − -gated channel.
PBO-4 Characterization
It has been demonstrated that initiation of the defecation cycle is a highly calcium regulated process, and that calcium spikes in the intestine correlate with the onset of the posterior body contraction (Dal Santo et al., 1999). Therefore, it is believed that the defecation cycle regulated by calcium. The pbo-4 gene encodes a putative Na + /H + exchanger that is expressed in the posterior intestine. Without wishing to be bound by theory, it is believed that calcium release in the intestine, through IP 3 receptors, results in the activation of PBO-4. Specifically, PBO-4 contains a consensus calmodulin-binding domain that is thought to be inhibitory to transport activity. Therefore, to activate PBO-4, Ca 2+ would bind the calmodulin site, thereby releasing inhibition and allowing proton transport, hi an exemplary embodiment, the secretion of H + by PBO-4 from the intestine, in a calcium dependent manner, PBO-4 is assayed for calcium binding and proton transport activity.
The posterior body contraction occurs via a calcium-regulated mechanism. The cloned and characterized pbo-4 gene, which encodes a Na + /H + exchanger, is expressed on the basolateral surface of the posterior intestinal cells, juxtaposed to the posterior body wall muscles. Utilizing caged protons, it has been demonstrated that acidification of the pseudocoelomic space, which separates the intestine from the body wall muscles, was sufficient to activate the posterior body contraction in vivo. These results suggest that PBO-4 Na + /H + transport activity is required to activate the posterior body contraction. Importantly, the identification of the PBO-5/8 receptor confirms that H + ions function as a primary transmitter in C. elegans . Furthermore, these results demonstrate that Na + /H + exchangers can function as a regulated H + release mechanism that mediates cellular signaling.
pbo-4 Mutations:
Allele Nucleotide Change Protein Change Sa300 GGA → AGA G318R n2658 GGTATTAA(Δ548 bp) GACAC Deletion of the C-terminus ok583 GCGACTCA (Δ1.702 Kb) aatttt Deletion of TM3- TM12 ok10 GCA → GAA A717D . . . 5 aa . . . Stop
PBO-8 Behavioral Characterization
In another exemplary embodiment, a deletion library is screened to identify an allele, for example, an allele of pbo-8. Optionally, RNAi technology may be used to knock out expression of PBO-8 or an ortholog/paralog identified in another organism. Any assay known in the art may be used to study a PBO-4, PBO-5, and/or PBO-8 ortholog/paralog, for example, RNAi technology, see U.S. Patent Applications 20030153519, 20030175772, 60/528,567, 60/518,856.
While this invention has been described in certain embodiments, 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.
All references, including sequence accession numbers, publications, patents, and patent applications, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
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Waldmann, R., Champigny, G., Bassilana, F., Heurteaux, C, and Lazdunski, M. (1997). A proton-gated cation channel involved in acid-sensing. Nature 386, YT1-XI1.
Waldmann, R., Champigny, G., Lingueglia, E., De Weille, J. R., Heurteaux, C, and Lazdunski, M. (1999). H(+)-gated cation channels. Ann N Y Acad Sci 868, 67-16.
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The invention relates to an isolated or recombinant Na + /H + exchanger comprising an isolated or recombinant Na + /H + exchanger, particularly to the PBO-4 Na + /H + exchanger. Also disclosed is an isolated or recombinant protein component of an H + -gated channel which can be affected by extracellular Ca 2+ concentration. In particular, the invention relates to PBO-5 and/or PBO-8 and/or a H + -gated channel composed of PBO-5 and PBO-8. The invention relates to compounds isolated from a vertebrate organism, wherein said compounds comprise at least a part of a H + -gated channel or Na + /H + exchanger. The invention also relates to a method for identifying a component of a H + -gated channel in a vertebrate organism.
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BACKGROUND OF THE INVENTION
This invention relates to electrical power transfer apparatus.
This invention has particular but not exclusive application to the transfer of electrical power from photovoltaic cells to electrical loads or energy storage devices, and for illustrative purposes reference will be made to such application. However, it is to be understood that this invention could be used in other electrical power generation applications in which is exhibited a predictable relationship between output power and a measurable operating characteristic, such as in thermoelectric converters.
Electrical power sources such as photovoltaic cells have a potential power output which varies widely according to the intensity of light to which they are exposed. In addition, for a given level of light intensity (insolation) such cells have a characteristic power output curve which relates the actual output power of a cell or array of cells to the resistance of the electrical load applied to them.
Photovoltaic cells individually have a relatively low power output, and are usually used in arrays of cells electrically connected in series, parallel, or series-parallel configurations. For the purposes of this specification, an array is to be taken to mean any number of cells connected in any useful configuration.
When the load resistance is infinite, the current is zero, and the power output, which is the product of voltage and current, is also zero. The voltage of a cell at this operating point is called the open circuit voltage. When the load resistance falls to zero, the short circuit current flows and the output voltage falls to zero. The power output at this point must consequently be zero as well.
For load resistances between infinity and zero, the product of the output voltage and the output current gives a measure of the output power of a photovoltaic cell. The voltage, current and power output as a function of the load resistance may be plotted for a particular cell. The plot is characteristically a smooth curve with a maximum output at a certain value of load resistance. A family of such curves may be plotted, each showing the cell characteristics at a certain value of insolation. For each curve, the power output peak occurs at a different value of load resistance.
In most applications, such as producing electric power from solar radiation, the insolation varies continually, as the sun rises and falls in the sky during the day, and as a result of changing cloud cover. The highest energy output over a period of time from a photovoltaic cell or an array of cells operating under conditions of varying insolation will be achieved if the resistance of the load applied to the cell is adjusted continually to ensure that the values of load resistance, voltage and current which lead to the highest output power at a particular value of insolation are always attained.
A further problem with photovoltaic cells is that the voltage at which they produce maximum power may bear no relationship to the voltage level required for certain applications such as battery charging or operating appliances where a fixed output voltage is necessary. This problem may be overcome by utilising a switching power converter. This is an electronic device which converts available input power to different voltage and current levels. Conventional switching power converters used with photovoltaic cells are unable to maximise the power delivery at any time, as they are unable to change their operating parameters to ensure that the photovoltaic cells operate at their maximum power point.
DESCRIPTION OF THE PRIOR ART
Power converters are known in which control is exercised by classical adaptive control theory. Convertor controllers of this type constantly perturb the set point and measure the effect of the perturbation on a selected output or input parameter. If an improvement is achieved, the controller moves the set point until perturbations of the control parameter in either direction produce a deterioration in the selected parameter. Such controllers are very complex in design and manufacture and have limited accuracy over wide dynamic ranges, and are consequently not suited to the control of power from typical photovoltaic installations.
A further problem with the design of power converters is that the switching semiconductors which switch the input current dissipate heat, and this heat must be conducted away from the semiconductors in order to maintain them at an acceptable operating temperature. Many methods of mounting switching semiconductors are in use. However, most methods require significant manual skill and complex installation procedures.
Active switching semiconductors are normally associated with passive switching semiconductors such as "freewheeling" diodes in typical converter designs. The inductance of the electrical conduction path between switching semiconductors and associated passive switching semiconductors must be minimised if the converter is to operate reliably and efficiently. Conventional mounting techniques frequently result in higher inductance levels than are desirable.
SUMMARY OF THE PRESENT INVENTION
The present invention aims to alleviate the above disadvantages and to provide power transfer apparatus which will be reliable and efficient in use. Other objects and advantages of this invention will hereinafter become apparent.
With the foregoing and other objects in view, this invention in one aspect resides broadly in power transfer control apparatus for controlling the supply of electrical power from a photovoltaic array to a load, said control apparatus including: a monitoring device for monitoring an operating characteristic of said array; a comparator connectible to said array and said monitoring device; and regulation means associated with said comparator for regulating the power transferred from said array.
Preferably, the regulating means regulates the power transferred from the photovoltaic array by controlling a switching power converter, although of course other controlling means may be used if desired, such as controlling the resistance of the load applied to the photovoltaic array.
Preferably, the monitoring device provides an indication of the open circuit voltage of the array by measuring the output voltage of the photovoltaic array while the output current is interrupted or reduced to zero, such as by inhibiting the operation of the switching power converter. Of course, if desired, other forms of providing an indication of the open circuit voltage of the photovoltaic array, such as measuring the open circuit voltage of an independent photovoltaic array, may be used.
The photovoltaic array output current may be interrupted for short sampling periods at random intervals. Preferably, however, the output current from the photovoltaic array is set to zero for regular sampling periods at regular intervals, and the sampling periods are made short relative to the intervals, whereby loss of output energy due to the interruption of power is minimised. Suitably, the current is interrupted for a sampling period of 50 milliseconds at intervals of ten seconds, but any combination of sampling period and sampling interval may be used if desired. Preferably, however, the ratio of sampling period to sampling interval is maintained at less than one percent, and the preferred value is one-half of one percent.
The open circuit voltage of the photovoltaic array is required continuously for use by the comparator. Suitably, the open circuit voltage may be maintained during the sampling intervals between sampling periods by any of the known sample and hold techniques of either the analog or digital types. Preferably, however, the open circuit voltage of the photovoltaic array is stored as a charge within a capacitor, the capacitor being charged to the open circuit reference voltage from the photovoltaic array through a blocking diode during the sampling period. The blocking diode minimises loss of charge in the capacitor to the photovoltaic array when the output voltage of the photovoltaic array falls while current is flowing from it. Suitably, a resistor is placed in parallel with the capacitor, whereby the voltage stored on the capacitor may fall gradually with time to permit the voltage stored on the capacitor to follow a reduction in the open circuit reference voltage of the photovoltaic array.
The comparator may provide an indication of the relative values between the open circuit voltage and the array output voltage and may control the regulation means to maintain the array output voltage at the desired fraction.
The regulation means may be operated to regulate the power transfer from the array to maintain the output voltage of the array at a selected fraction of the indicated open circuit voltage. Preferably, the selected fraction is maintained at a constant value which may, if desired, be within the range of between 0.75 and 0.80. This fraction has found to provide a condition close to the maximum power output of the photovoltaic array for any level of insolation.
The switching power converter may be also have its operating characteristics controlled by feedback from the input or output of the switching power converter, whereby the output of the power conversion apparatus may be controlled to maintain selected voltage or current charactistics, such as a constant output voltage for purposes such as maintaining a battery float voltage level after a battery has been fully charged.
In a further aspect, this invention resides in a method of transferring power from a photovoltaic array to a load including:
maintaining the output voltage from said photovoltaic array at a voltage between 0.75 and 0.80 of the open circuit voltage of said photovoltaic array; and
feeding said power from said photovoltaic array to said load.
In yet another aspect, this invention resides in a method of constructing electronic switching apparatus including:
using a length of hollow extruded aluminium alloy box section as a heat sink;
placing a switching semiconductor on a side of said box section at a lower end;
placing a further switching semiconductor on the opposite face of said side and adjacent said switching semiconductor;
attaching said switching semiconductor and said further switching semiconductor to said box section by means of a common fastener passing through an aperture in said box section, said fastener connecting said switching semiconductor and said further switching semiconductor, and clamping said switching semiconductor and said further switching semiconductor to said box section, whereby heat transfer between said switching semiconductor and said box section is enhanced; mounting further electronic components on a printed circuit board;
attaching the leads of said semiconductor and said further switching semiconductor to a printed circuit board adjacent one another, whereby inductive effects in the conductive path between said semiconductor and said further switching semiconductor are minimised, and whereby an end of said box section is brought adjacent said printed circuit board; placing encapsulating material within said box section.
In order that this invention may be more easily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate preferred embodiments of the invention, wherein:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graph of typical voltage-current characteristics for a photovoltaic array;
FIG. 2 is a block diagram of a power conversion apparatus;
FIG. 3 is a block diagram of an alternative power conversion apparatus, and
FIG. 4 is a pictorial view of electrical switching apparatus.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a set of voltage-current curves 10, 11 and 12 for various values of solar insolation at particular temperatures. The voltage-current curves 10, 11 and 12 intersect the current axis 13 at short-circuit current points 14, 15 and 16 respectively, and these points show the values of short-circuit current which are obtainable from a photovoltaic array at the prevailing conditions. The voltage-current curves 10, 11 and 12 also intersect the voltage axis 17, the intersections being the open-circuit voltage points 18, 19 and 20 respectively, and these points show the values of open circuit voltage which are obtainable from a photovoltaic array at the prevailing conditions.
Maximum power points 21, 22 and 23 are the points on respective curves 10, 11 and 12 at which the product of voltage and current is a maximum. The locus of maximum power points 24 is a curve passing through the maximum power points for all voltage-current curves. To achieve the maximum possible power output from the photovoltaic array for a range of prevailing conditions, it is necessary to change the load on the photovoltaic array such that the current-voltage conditions of the photovoltaic array remain on the locus of maximum power points 24.
The projections from the maximum power points 21, 22 and 23 onto the voltage axis 17 produce the maximum power point voltages 25, 26 and 27. For the photovoltaic array to which FIG. 1 refers, the division of the maximum power point voltages 25, 26 and 27 by the respective open circuit voltages 18, 19 and 20 yields a constant of value 0.77.
The power converter apparatus 40 shown in FIG. 2 derives its power from a photovoltaic array 41 made up of photovoltaic cells 42. The positive terminal 43 and the negative terminal 44 of the photovoltaic array 41 are connected to the switching power converter 45, and the latter is, in turn, connected to a load 46.
An oscillator 47 is connected to an inhibiting control function on the switching power converter 45 and inhibits the operation of the switching power converter 45 for fifty milliseconds every ten seconds. A diode 51 has its anode connected to the positive terminal 43 of the photovoltaic array and its cathode connected to a capacitor 52. The other terminal of the capacitor 52 is connected to the negative terminal 44 of the photovoltaic array 41.
An upper resistor 53 and a lower resistor 54 form a resistive divider across the capacitor 52, and the junction between the resistors 53 and 54 is connected to one input of a comparator 57. The other input to the comparator 57 is connected to the common connection point of a resistive divider comprising a positive-rail resistor 55 and a negative-rail resistor 56.
The relative values of the resistors 53 and 54 and 55 and 56 are arranged such that the voltages applied to the inputs of the comparator 57 are equal when the voltage between the terminals 43 and 44 of the photovoltaic array 41 is seventyseven percent of the voltage across the capacitor 52. The output of the comparator 57 is connected to a regulator 58 which controls the switching power converter 45.
In use, electric power is produced by the photovoltaic array 41 and fed to the switching power converter 45, which converts the available power to a voltage and current appropriate to the resistance of the load 46.
Every ten seconds, the oscillator 47 inhibits the operation of the switching power supply 45 for fifty milliseconds. During this period, the current drawn from the photovoltaic array 41 falls to zero, and the voltage across the terminals 43 and 44 of the photovoltaic array 41 rises to the open circuit voltage of the photovoltaic array. Current flows through the diode 51 to charge the capacitor 52 to a voltage approaching the open circuit voltage of the photovoltaic array 41.
When the oscillator 47 ceases to inhibit the operation of the switching power supply, the voltage across the terminals 43 and 44 falls to its loaded value, and the diode 51 minimises flow of current away from the capacitor 52. The relative values of voltage between the terminals 43 and 44 and the voltage across the capacitor 52 are constantly compared by the comparator 57, and the output from the comparator 57 signals the regulator 58 to increase or decrease the power flow from the photovoltaic array 41 according to whether the operating voltage of the photovoltaic array 41 is less or more than seventy-seven percent of the open-circuit voltage of the photovoltaic array 41, as determined by the voltage across the capacitor 52.
The comparator 57 compares these voltages, and controls the regulator 58 to maintain the voltage across the terminals 43 and 44 at seventy-seven percent of the voltage across the capacitor 52.
The charge on the capacitor 52 gradually leaks away through the resistors 53 and 54, allowing the voltage across the capacitor 52 to fall gradually such that it may follow a fall in the open circuit voltage of the photovoltaic array.
As shown in FIG. 3, the power converter apparatus 60 derives its power from a photovoltaic power array 61 made up of photovoltaic cells 62. A separate reference array 63 made up of photovoltaic cells 62 is located in close proximity to the power array 61 such that it experiences similar insolation and temperature conditions to the power array 61.
The open-circuit voltage of the reference array 63 will, under these conditions, maintain direct proportionality with the open-circuit voltage of the power array 61. The positive terminal 64 and the negative terminal 65 of the power array 61 are connected to the switching power converter 66, and the latter is, in turn, connected to a load 67.
A comparator 68 has one of its input terminals connected to the centre point of a resistive divider comprising a positive-rail resistor 69 and a negative-rail resistor 70. The negative terminal of the reference array 63 is connected in common with the negative terminal 65 of the power array 61, while the positive terminal of the reference array 63 is connected to a resistive divider formed of an upper resistor 71 and a lower resistor 72. The junction of the resistors 71 and 72 is connected to the second input terminal of the comparator 68.
The relative values of the resistors 69 and 70 and 71 and 72 are arranged such that the voltage difference between the inputs to the comparator 68 is zero when the voltage across the power array 61 is seventy-seven percent of the voltage across the reference array 63 after allowing for the ratio of the respective open-circuit voltages of the arrays 61 and 63. The output of the comparator 68 controls a regulator 73, which in its turn, regulates the operation of the switching power converter 66.
In use, electric power is produced by the power array 61 and fed to the switching power converter 66, which converts the available power to a voltage and current appropriate to the resistance of the load 67.
The relative values of voltage between the terminals 64 and 65 and the voltage across the reference array 63 are constantly compared by the comparator 68, and the output from the comparator 68 signals the regulator 73 to increase or decrease the power flow from the power array 61 according to whether the operating voltage of the power array 61 is less or more than seventy-seven percent of the open-circuit voltage of the power array 61, as determined by the open-circuit voltage of the reference array 63.
The electrical switching apparatus 80 shown in FIG. 4 includes a first switching semiconductor 81 and a second switching semiconductor 82. The first switching semiconductor 81 is mounted on the inside face 83 of a heatsink 84, and the second switching semiconductor 82 is mounted on the outside face 85 of the heatsink 84 opposite the switching semiconductor 81.
The switching semiconductors 81 and 82 are electrically insulated from the heatsink 84 by thin sheets of mica insulation 86, and are clamped into contact with the heatsink 84 by means of a bolt 87 which passes through an aperture 88 in the heatsink 84, and which is insulated from the heatsink 84.
The connecting leads 89 from the base of the switching semiconductors 81 and 82 pass through lead apertures in the printed circuit board 90 and are soldered to conductive tracks on the underside of the printed circuit board 90. Encapsulating material 91 is placed within the enclosure formed by the heat sink and the printed circuit board.
It will of course be realised that while the above has been given by way of illustrative example of this invention, all such and other modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is defined in the appended claims.
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Electrical power transfer apparatus (40) for controlling the supply of electrical power fram an array of photovoltaic cells (41) to an electrical load (46) by means of a switching power converter (45). The switching power converter (45) is controlled by a regulator (58) to maintain the output voltage from the photovoltaic array (41) at a fixed fraction of the open circuit voltage of the photovoltaic array (41), the fixed fraction suitably being between 0.75 and 0.8, whereby the power transfer from the photovoltaic array (41) is maximized. The open circuit voltage of the photovoltaic array (41) is sensed by inhibiting the operation of the switching power converter for short sampling periods at regular intervals, and allowing a capacitor (52) to charge to the voltage of the open-circuited photovoltaic array (41) during the sampling periods.
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BACKGROUND OF THE INVENTION
This invention relates to switching circuits, and in particular to circuits including a pair of switching elements each of which can be caused by an input pulse to conduct for an output pulse.
Problems can arise if, owing to differences between the switching elements, the output pulses for the two elements are unequal in duration. An example occurs when the switching elements are semiconductors connected in push-pull configuration and driving an output transformer, and the circuit is operated as the inverter stage of a power supply. In that case differences in the durations of the output pulses can drive the transformer into saturation, with increased and possibly destructive dissipation in one of the semiconductors.
An important factor influencing differences in conduction time in semiconductors is the storage time, which results from the presence of injected minority carriers in the base or gate region of the semiconductor at the time when the input current is cut off. One way of overcoming the problem is by carefully selecting the semiconductors as matched pairs, with equal storage times. However, such selection is time-consuming and often not completely satisfactory since the storage times of the semiconductors tend to drift by different amounts with age and temperature. It has also been proposed to control the duration of the input pulses by a feed-back loop which compares the output pulses from the two semiconductors and alters the ratio between the input pulses to the two semiconductors in such a way as to tend to make the output pulses the same.
SUMMARY OF THE INVENTION
This invention provides a switching circuit comprising a pair of switching elements and a drive circuit for applying input pulses to the switching elements, each switching element being caused by an input pulse applied to it to conduct for an output pulse, and the drive circuit controlling the duration of the input pulses applied to each switching element in response to the durations of the output and input pulses of the other switching element in such a manner as to make the duration of the input pulses applied to each switching element substantially equal to a reference duration common to both switching elements plus the difference between the duration of the output and input pulses of the other switching element.
In a modification of the invention the duration of the input pulses applied to each switching element is controlled in response to the durations of its own output and input pulses in such a manner as to make the duration of the input pulses applied to each switching element substantially equal to a reference duration common to both switching elements less the difference between the durations of its own output and input pulses.
BRIEF DESCRIPTION OF THE DRAWINGS
Two forms of apparatus constructed in accordance with the invention will now be described in greater detail by way of example with reference to the accompanying drawings, in which:
FIG. 1 is a simplified circuit diagram illustrating the principle of operation of the first form;
FIG. 2 shows the semiconductors and sensing circuit of the first form;
FIG. 3 is a circuit diagram of the drive circuit of the first form;
FIG. 4 shows diagrammatically the waveforms at the points of FIG. 3 marked with the corresponding letter; and
FIG. 5 is a simplified circuit diagram of the second form.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, the apparatus is a d.c. to d.c. converter, converting a d.c. voltage supplied to terminals V+ and V- to a d.c. voltage that is output at terminals W+ and W-. The circuit is in two main parts: an inverter stage converting the d.c. voltage to a train of a.c. pulses, and a rectifying and smoothing stage. Such circuits allow regulation of the output voltage by control of the pulse duty-cycle.
In the inverter stage two transistors TR1, TR2 are connected in push-pull configuration between the terminals V+ V-, a pair of capacitors C1, C2, and an output power transformer TX. In operation, input pulses are applied alternately to the transistors TR1, TR2 so as to cause them to conduct alternately (class B operation). This results in voltage pulses of alternate polarities across the primary of the transformer.
The output appearing at the secondary of the transformer is rectified and smoothed in the second stage by a circuit comprising two diodes D1, D2, a capacitor C3 and an inductor L to produce a d.c. output of the required magnitude.
The input pulses for the transistors are produced by an arrangement which, to help explain its principle of operation, will be regarded for the present as a pulse source producing a series a reference pulses of length T r directed alternately to two pulse-length adding circuits 11, 12. (It is to be understood that the term "length," when applied herein to pulses, is synonymous with "duration."
The input to the base of transistor TR1 is a pulse of length T cl . This causes the transistor TR1 to conduct, and to produce an output pulse of length T w1 = T cl + T sl where T sl is the difference between the input and output pulses (basically the storage time). The sensing of the output pulses is shown diagrammatically only in FIG. 1. The input and output pulses of the transistor TR1 are both applied to the subtracting circuit 14, which produces a pulse of length equal to the difference in lengths of these two pulses i.e.
T.sub.w1 - T.sub.cl = T.sub.sl
The output pulse from the circuit 14 is stored in the adding circuit 12, and then added to the next reference pulse. The circuit 12 thus produces a pulse of length T.sub. c2 = T r + T sl , and this pulse is applied as input to the base of transistor TR2, causing it to conduct.
The difference between the output and input pulses of the transistor TR2 is measured by the subtraction circuit 13, in the same way that T sl was measured, and the output pulse from the circuit 13 is stored in the adding circuit 11 and then added to the next reference pulse. The circuit 11 thus produces a pulse of length T cl = T r + T s2 which is applied as input to the transistor TR1.
It can be seen that the conduction times of the two transistors are given by:
T.sub.w1 = T.sub.cl + T.sub.sl = T.sub.r + T.sub.s2 + T.sub.sl
T.sub.w2 = T.sub.c2 + T.sub.s2 = T.sub.r + T.sub.sl + T.sub.s2
and are therefore effectively identical despite any variations in T sl and T s2 .
The first form will now be described in more detail.
Referring to FIG. 2, the input pulses are delivered to the transistors TR1 and TR2 along lines 21 and 22 through base drive circuits (not shown). The output pulses are taken from an extra winding 23 on the output transformer Tx, which produces voltages suitable for inputting to transistor logic. The winding 23 is centre-tapped and outputs opposite-polarity waveforms on line 24 and 25.
Referring to FIG. 3, in the actual drive circuit the functions of the two subtracting circuits are carried out by the same equipment, as are the functions of the two adding circuits 13 and 14 (although this combination is of course not essential). And instead of a source of pulses of a reference duration, a train A of fixedlength clock pulses (see also FIG. 4) is supplied to a terminal 26 and the reference duration is derived electronically.
The clock pulses A trigger a bistable 27 which enables two AND gates 28 and 29 in turn. They direct the output waveform B of the drive circuit, consisting alternately of pulses of duration T cl and T c2 each starting at the start of a clock pulse, to the two transistors TR1 and TR2 alternately
The transistors conducts for pulses of length T w1 or T w2 each having a ramp top formed as the primary current increases against the impedance of the load (waveforms C.) The result induced in the sense winding 23 is a waveform D on the line 24 and its inverse D on the line 25. The positive-going pulses of these two waveforms are added by an OR-gate 30 to give a waveform E.
An EXCLUSIVE-OR gate 31, which produces an output only when it receives a single input, subtracts the input waveform B from this waveform E and outputs pulses F of length T sl and t s2 . An output from the gate 31 closes a normally-open switch 32, allowing a constantcurrent source 33 to charge (waveform G, solid) a capacitor 34, which will just have been discharged by a switch 35 being closed momentarily. The final voltage across the capacitor 34 is thus proportional to the length of the pulse from the gate 31.
At the start of each half-cycle a switch 36 is opened allowing a capacitor 37 to be charged from a constant-current source 38 (waveform H, dotted). The voltages across the capacitors 34 and 37 are applied to the positive and negative inputs of a comparator 39; when the voltage across the capacitor 37 equals that across the capacitor 34 the output of the comparator 39 (waveform I) switches from high to low.
The capacitor 37 charges at the same rate as the capacitor 34. Therefore, the time from the start of the half-cycle to the point at which the comparator 39 switches is equal to the length of the pulses from the gate 31, that is, T sl or T s2 . This part of the circuit has thus stored a representation of the pulse from the gate 31 and reproduced the pulse starting at the beginning of the next half-cycle. When the comparator 39 switches to low, a switch 40 opens, allowing a capacitor 41 to be charged from a constant current source 42 (waveform J). (The three constant current sources 33, 38, and 42 are provided, in known manner, by transistors with constant base voltages provided by Zener diodes and are formed as a single network. The three switches 32, 37, and 40 are transistor switching elements in a single, commercially supplied package.)
The voltage across the capacitor 41 is compared to a reference voltage by a comparator 43, which switches its output (waveform K) when the reference voltage is equalled. The time that takes to happen depends on the value of the reference voltage and is equivalent to the reference pulse length in the simplified description with reference to FIG. 1. The total time from the start of the half-cycle to the change of state of the comparator 43 is thus T sl + T r during a half-cycle supplying an input pulse to the transistor TR2 and T sl + T r during half-cycle supplying an input pulse to the transistor TR2.
The waveform K is inverted by an inverted 44 to become the waveform B which is split to form the actual input pulses for the transistors.
The comparator 43 is connected to remain high until inhibited by a control signal formed by the start of any of the clock pulses, when the waveform K again becomes low. While it is low the switch 36 is held open, thus starting the charging of the capacitor 37 at the beginning of a half-cycle. The leading edge of the waveform K is also converted by a pulse-forming circuit 45 into a momentary pulse which, as mentioned, closes the switch 35 to discharge the capacitor 34.
Referring to FIG. 5, in the second form of apparatus, after the input pulse for the transistor TR1 has been subtracted from its input pulse by the circuit 4, the difference between them is subtracted from the reference pulse by a circuit 15 to give the input pulse for that same transistor TR1, rather than added to give the input pulse for the other transistor. And for the transistor TR2 the output of the subtraction circuit 13 is subtracted from the reference pulse by a circuit 16 to give its input pulses.
The output pulse from the transistor TR1 is therefore given by
T.sub.w1 = T.sub.cl + T.sub.sl = T.sub.r - T.sub.sl + T.sub.sl = T.sub.r
and the output pulse from the transistor TR2 by
T.sub.w2 = T.sub.c2 + T.sub.s2 = T.sub.r - T.sub.s2 + T.sub.s2 = T.sub.r
Thus the two output pulses are again effectively equal.
In the actual circuit there are two separate channels for the two transistors because the difference durations need to be stored for a full cycle, that is, while the input pulse for the other transistor is being generated in the intervening half-cycle. Each channel corresponds generally to the appropriate part of FIG. 3, except that, for each, the voltage across a capacitor corresponding to the capacitor 34 and holding the pulse-difference, is subtracted from the reference voltage by an analogue subtractor, the result forming the negative input to the comparator corresponding to the comparator 43. And a capacitor corresponding to the capacitor 41 starts to charge at the start of the cycle. It then reaches the voltage of the other input after the reference duration less the pulse difference.
In both these forms of apparatus the single transistor of each limb of the inverter circuit can be replaced by a network of more than one transistor. In this network each transistor is connected to the next by a transformer in its emitter path in such a way that the currents through all the transistors of the network are forced to remain balanced. This allows the power rating of the circuit to be increased without the danger that, owing to differences between the parameters of different transistors, one draws more than its calculated share of current and fails. With this arrangement the difference between the output and input pulses will not be determined by the parameters of any particular transistor.
The output of the circuits can be varied by altering the reference voltage, which effectively modulates the reference pulse-width. The reference voltage can for example by an error voltage from a regulator circuit comparing the actual output W+, W- of the converter with a desired value.
The output pulses in these forms of circuit are equalised in at most a few half-cycles. This may be compared with an analogue circuit which attempts to equalise the pulses by a feed-back circuit responsive to the difference between them, which typically takes some 50 to 100 cycles to equalise the output pulses.
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An inverter switching circuit, for example for a power supply, including semiconductors in push-pull configuration. To compensate for differences (basically in storage time) between the semiconductors in the two limbs the input pulse to each limb is of a reference duration plus the difference between the output and input pulses of the other limb. In a modification the input pulse for each limb is of the reference duration less the difference between its own output and input pulses.
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RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent application Ser. No. 09/958,221, filed Apr. 15, 2002, now U.S. Pat. No. ______, issued, ______, 2003, which is a national stage of international application PCT/NL01/00177, filed Mar. 5, 2001.
TECHNICAL FIELD
[0002] The invention relates generally to methods and materials for the genetic analysis of a subject.
BACKGROUND
[0003] For some species, reliable, simple technologies are available for genetic analysis of individuals. However, for most animal and bird species, genetic information is insufficient for applied genetics. Developing existing technologies for each species to obtain genetic data will be extremely laborious and time consuming. Progress to date has been slow. The situation is particularly problematic in the area of wildlife management. For example, building DNA patterns of hawks is currently almost impossible. At the same time, there have been reports of people illegally placing eggs from wild mating hawk couples in tamed breeding hawk nests. It is currently nearly impossible to prove fraud using DNA data in species where genetic variation has not been previously described.
[0004] Other areas of interest are DNA identification of exotic species (e.g., animals, plants, organisms) for various reasons. For instance, animals arriving through veterinary control can be identified by sampling them both at departure and at arrival. Using the animal's individual DNA to identify it, animals can be tracked, and proof of their origin is always possible.
[0005] Furthermore, parentage verification in rare, expensive animals and strain identification of plants can be performed for any given combination or species. Reports have been made of selling the offspring of “lower” breeding parents as the highest possible quality been made of selling the offspring of “lower” breeding parents as the highest possible quality animals.
[0006] Another problem is the determination of sex. For many exotic species, genetic markers are not available to perform sex determination.
[0007] A need exists for a method of quickly genetically analyzing a species to determine, among other things, its lineage, sex, and origin.
BRIEF SUMMARY OF THE INVENTION
[0008] The invention provides a new technology which has been developed for the quick genetic analysis of a species and individuals thereof. The method includes the use of first and second oligonucleotide primers for performance of PCR amplification on the genomic DNA. The first oligonucleotide primer is a 5′ variation generator, including a repeat sequence and at least one non-repeat nucleotide. The second oligonucleotide primer is a 3′ fragment generator starting within such a genetic distance that amplification of the genomic DNA can be performed and preferably includes inosine. PCR amplification of the genomic DNA is conducted at a relatively low annealing temperature using both the first and second oligonucleotide primers under conditions such that essentially neither the first nor the second oligonucleotide primer alone can amplify sufficient DNA to be detected. DNA fragments are thus produced based on repeat sequences on one end of the genomic DNA, and other sequences based on the opposite end of the genomic DNA. The resulting PCR products can then be analyzed for the length of a repeat sequence found in the genome. A second PCR is preferably conducted on the diluted PCR products of the first PCR. Such a second PCR would be conducted using third and fourth oligonucleotide primers. The third and fourth oligonucleotide primers are elongated versions of the first and second oligonucleotide primers, respectively, thus enabling PCR amplification at relatively higher annealing temperatures and enabling a selection of a sub-set of the DNA fragments amplified in the first PCR. At any point, an optional but preferred restriction digestion may be conducted. The technology has been developed for the quick genetic analysis of a species which is reliable, reproducible, simple, and useful for all species/organisms (e.g., animal, avian, bacterial, viral, and plant). The invention particularly relates to samples obtainable from non-human species but is applicable to samples obtained from humans as well. Neither variation in genome length nor genome composition appears to influence or limit the characteristics of the technology. This new technology is generally reliable, reproducible, simple, and useful for all species/organisms (e.g., animal, avian, bacterial, viral, and plant). Furthermore, any material containing DNA (e.g., blood, hair follicles, etc.) can be used as a source for the generation of DNA patterns.
[0009] In one aspect, the invention includes a method of analyzing genomic DNA in a sample. This method includes providing first and second oligonucleotide primers, wherein the first oligonucleotide primer is a “5′ variation generator” comprising a repeat sequence and at least one non-repeat nucleotide on the first oligonucleotide's 5′ end. Meanwhile, the second oligonucleotide primer is a “3′ fragment generator” starting within such a genetic distance that amplification of the genomic DNA can be performed. A nucleic acid amplification such as a polymerase chain reaction (“PCR”) amplification is conducted on the genomic DNA in the sample using both the first and second oligonucleotide primers. The nucleic acid amplification is conducted under conditions such that neither the first nor the second oligonucleotide primer alone amplifies DNA, thus producing DNA fragments based on repeat sequences on one end of the genomic DNA and other sequences based on the opposite end of the genomic DNA. The amplified products are then analyzed to determine the length of a repeat sequence found in the genomic DNA, which can be compared with the DNA putatively of the same individual or the DNA of the individual's putative ancestors or relatives.
[0010] Alternatively, and as more thoroughly described hereinafter, multiple amplifications and/or restriction digestion might also be used with the technique.
[0011] As described herein, the first primer, the “5′ variation generator,” includes a complementary repeat sequence and at least one non-repeat nucleotide so as to start the amplification at a repeat sequence of the genomic DNA.
[0012] By localizing the 5′ variation generator at the 5′ site of repeat sequences, the repeat length variation is enclosed in the amplification rounds. Primers are thus bound to hybridize at the 5′ ends of repeat sequences by addition of one or more nucleotides at the end of the primer.
[0013] While the oligonucleotide primers at repeat sequences provide detection of genetic variation, the 3′ fragment generator is used to amplify fragments of reasonable sizes (e.g., 100 base pairs to 10,000 base pairs). The 3′ fragment generator starts within such a genetic distance that amplification of a sample DNA can be performed and preferably includes inosine or another a-selective base allowing it to influence annealing temperatures without coincident or equal influence on the stringency of the annealing reaction. The 3′ fragment generator is designed to anneal to the DNA within a short distance, as mentioned before. To do this, the number of selective nucleotides is kept at a low number, whereas the annealing temperature is influenced by a number of non-selective nucleotides, such as inosines, universal bases, and any combination of A, C, G or T (e.g., R, Y, N). By using such a 3′ fragment generator, the invention provides optimal reaction conditions in the reaction that are generally well suited to the reaction conditions required for the 5′ generator. In short, the number of selective nucleotides of this primer is maintained at a relatively low number, whereby the annealing temperature is raised to enable reliable and reproducible amplification using a-selective bases, such as inosines, in the fragment generator oligonucleotide.
[0014] Some of the genetic markers identified using the technology will be located on the male and female sex chromosomes. After the identification of such markers, these markers can be used to determine the sex of species which are difficult to establish through phenotypic characteristics (e.g., porcupine or crocodile).
[0015] The invention also includes a kit of parts for performing the genetic analysis and a method of manufacturing such kit for use in genetic analysis. The invention is further described in the detailed description without limiting the invention thereto.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The samples used in the illustrations are based on high molecular weight DNA obtained from blood samples from each animal.
[0017] FIG. 1 illustrates the analyses of five species. Clear differences are present. Different lanes present 1) horse, 2) parrot, 3) cattle, 4) ostrich and 5) pig. The illustration shows DNA fragments ranging from sizes between 100 and 1200 bp.
[0018] FIG. 2 is an illustration of the analyses of five species. Clear differences are present. Different lanes present 1) horse, 2) parrot, 3) cattle, 4) ostrich and 5) pig. The illustration shows DNA fragments ranging from sizes between 250 and 300 bp.
[0019] FIG. 3 depicts the variation within species. Two samples of the same species (ostrich) are presented. At least three loci are presented.
DETAILED DESCRIPTION OF THE INVENTION
[0020] To combine the amplification of many DNA fragments with the selection of a specific set of informative DNA fragments, a preferred protocol is used which is based on two subsequent PCR amplifications. PCR is one of many well-known amplification methods known in the art and is, therefore, not described further here.
[0021] In a preferred method, genomic DNA from the sample is amplified in a first PCR at relatively low annealing temperatures. The 5′ variation generator and the 3′ fragment generator are used to generate fragments of which a selected part is to be used in a second PCR. The first PCR is usually run under conditions under which neither the 5′ variation generator nor the 3′ fragment generator alone amplify DNA. Thus, when DNA amplification is performed using both the 5′ variation generator and the 3′ fragment generator, many resulting fragments are based on repeat sequences on one end of the genomic DNA and, at the same time, many sequences are based on an opposite end of the genomic DNA.
[0022] After possible dilution of the PCR products of the first PCR, a second PCR is preferably performed. This second PCR is conducted using third and fourth oligonucleotide primers. The third and fourth oligonucleotide primers are commonly elongated versions of the first and second oligonucleotide primers, respectively, thus enabling PCR amplification at relatively higher annealing temperatures and enabling a selection of a sub-set of the DNA fragments amplified in the first PCR. The fourth oligonucleotide primer preferably includes inosine residues.
[0023] At any point during this procedure, a preferred, but optional, restriction digestion may take place. Another source of genetic variation in amplified fragments is the presence or absence of restriction sites. Addition of a restriction digest after the second PCR increases the number of genetic polymorphisms detected. Furthermore, the sizes of the DNA fragments to be analyzed for their length are decreased as well.
[0024] The amplified PCR products can then be analyzed using a variety of existing methods.
[0025] As can be determined, many DNA fragments are amplified in the first PCR amplification, whereas a subset of these DNA fragments are multiplied in the second PCR amplification. Both reactions are preferably run under stringent conditions. Primers used in the PCR procedure can vary in length. Lengths between 4 and 50 nucleotides or inosines were used in the examples.
[heading-0026] Primer Design
[0027] As previously identified, the variation generator starts at a repeat sequence, while the fragment generator starts within such a genetic distance that amplification of the DNA can be performed.
[0028] For the 5′ variation generator, repeat sequences exist throughout any genome in many variations, such as mononucleotide (A, G, C or T) repeat, dinucleotide (CT, CA, CG, AT, AC, AG, GT, GC, GA, TA, TG and TC) repeat, trinucleotide (e.g., TGA, CTG, etc.) repeat, tetranucleotide (e.g., TGCA, CTGT) repeat, and so forth. For instance, an AC repeat can have the structure: CACACACACACA (SEQ ID NO:1) (“6-repeat”), or CACACA (SEQ ID NO:2) (“3-repeat”).
[0029] Repeat sequences, of course, also exist in the as yet unanalyzed genomes of species. Repeat sequences exhibit different lengths due to the number of repeats present. For different individuals, differences exist in the numbers of repeats in each locus (“microsatellite”). Thus, genetic variation in repeat sequences can be determined based upon length variation caused by the number of nucleotide repeats in a locus. The number of repeats in a microsatellite can vary enormously with different individuals of the species. Many sequences contain a few repeats (e.g., 2 or 3), whereas some repeats are known to include thousands of base pairs (“bp”).
[0030] By localizing the oligonucleotide primer at the 5′ site of repeat sequences, as described herein, the repeat length variation is enclosed in the amplification rounds which are part of PCR. Primers are forced to hybridize at 5′ ends of repeat sequences by adding one or more nucleotides which do not continue the repeat pattern at the 5′ end of the primer. This result is due to the nature of the amplifying enzyme, which elongates DNA fragments starting from the 3′ end of oligonucleotide primers.
[0031] While the choice of oligonucleotide primers at repeat sequences provides most of the detection of genetic variation, the 3′ fragment generator is essentially used to amplify fragments of reasonable sizes (100 bp to 10,000 bp).
[0032] The number of selective oligonucleotides of the primer is maintained at a low number. At the same time, the annealing temperature is raised to enable reliable and reproducible amplification. This is done using inosine substitutions in the fragment generator. Inosines are used to increase annealing temperatures without affecting the binding conditions of oligonucleotides. Inosines match to any of the four nucleotides in the DNA. When inosine is substituted for a nucleic acid, it contributes to the sensitivity of the technique.
[heading-0033] PCR
[0034] To combine the amplification of many DNA fragments with the selection of a specific set of informative DNA fragments, a protocol is used which is based on two subsequent PCR amplifications. In the first PCR amplification, many DNA fragments are amplified, whereas in the second PCR amplification, a subset of these DNA fragments are multiplied. Both reactions are run under stringent conditions.
[0035] After the PCR (or PCRs) have been conducted, the resulting amplified fragments are preferably subjected to restriction digestion to determine the presence or absence of restriction sites. Use of the restriction enzymes increases the number of genetic polymorphisms detected.
[0036] The (preferably digested) product is then sequenced using techniques known in the art to determine the particular genetic patterns or markers present, when so desired.
[heading-0037] Applications
[0038] The nature of universal variable fragments (UVF) combines flexibility and reproducibility with high levels of polymorphisms. The 5′ variation generator (based on the microsatellite sequence) mostly corresponds with the genetic variation typically found in microsatellites, whereas the 3′ fragment generator is mainly linked to presence/absence polymorphisms. This strategy is typically based on the use of two different fluorescent labels-one associated with the 5′ variation generator, the other corresponding to the 3′ fragment generator. This concept enables the optimal use of high throughput analysis systems based on multiple fluorescent dyes.
[0039] In comparison with other technologies, e.g. AFLP, UVF has an increased power to generate polymorphisms in search for high marker density. One distinct advantage of the UVF system is found in the possibility to increase the marker density in regions of chromosomes of specific interest by choosing the order of the bases of the 3′ fragment generator, instead of random, in the flanking region of a known genetic marker. As a result, a number of genetic markers can be identified within a short distance from, e.g., QTL markers. This prospect is not possible with other technologies such as AFLP (and SAMPL), or ISSR (Inter Simple Sequence Repeat).
[0040] Compared to several technologies, UVF is different:
[0041] a) The power to generate polymorphisms is much larger compared to RAPD (random amplified polymorphism detection). Due to its concept of a three-step strategy, UVF has increased power to generate polymorphisms. RAPD is based on only one primer in just one PCR, whereas UVF is typically based on two consequent PCR amplifications, followed by a digestion step.
[0042] b) Amplification using ISSR (Inter Simple Sequence Repeat) is based on one primer in one PCR reaction. UVF is completely different based on typically two PCR amplifications and the use of a digestion step.
[0043] c) Amplified Fragment Length Polymorphisms (AFLP) is based on the use of adaptor ligation to initiate PCR. This procedure is typically completely absent in UVF, as is the obligation to start the reaction with a digestion of several restriction enzymes.
[0044] d) SAMPL is completely based on AFLP, but is directed to the detection of microsatellites using the AFLP technology.
[0045] Furthermore, compared to RAPD and microsatellite analysis, the power of the present invention to generate large amounts of polymorphisms from a small amount of genomic DNA is clear.
[0046] Several areas for applications based on UVF include:
[0047] 1. Gene Hunting
[0048] The detection and identification of genetic markers for diseases or beneficial genetic characteristics is possible using UVF. Due to its effectiveness, even in species with a relatively well-developed genetic map, UVF is useful. In other species where the number of available genetic markers is low, UVF will be the technology of choice.
[0049] 2. Marker Density
[0050] In situations where QTL analysis has revealed a genetic marker (e.g., RFLP or microsatellite) with known sequence, the number of markers in a defined region can be increased using the UVF technology. This can be achieved by locating the nine bases of the 3′ fragment generator in the flanking region of the polymorphic marker. This enables generation of genetic markers in specific areas of interest. Using this approach, the range in which QTLs may be located can be decreased, and, for example, “candidate gene approach” can be more directed.
[0051] This strategy can be further used to detect genetic variation in the genomic regions close to promoter sites located close to genes. The design of the 3′ fragment generator can be based on general promoter sites or on sequences recognized by transcription factors. This further illustrates the power of UVF over other available technologies.
[0052] 3. Forensic Analysis
[0053] Due to the nature of UVF, small quantities of DNA can be used to generate DNA profiles. This enables the use of UVF in situations where only limited amounts of DNA are available for genetic analysis, e.g., forensics.
[0054] 4. Biodiversity
[0055] UVF enables the search for breed- and species-specific markers. Among other issues, (sub)-species identification of, for example, birds will solve many enduring discussions.
[0056] In use, the invention is quite straightforward. The invention provides rapid and straightforward identification of endangered animals and plants. Many wildlife species, both animals and plants, are protected by law. Only limited numbers of individuals may be kept in private. However, identification and lineage of these individuals needs to be proven to effectively protect the law. The invention provides the means to answer any question in wildlife management relating to identity or lineage, also of species of which specific sequences are little known. The invention also provides genetic maps of a species. In some species, genetic information, and certainly genetic maps, are underdeveloped. Usually, identification of genetic markers is time and labor consuming using the existing methodologies (e.g. microsatellites).
[0057] Furthermore, testing of these markers is inefficient due to the low number of genetic markers amplified in one, single reaction.
[0058] With this new technology, genetic markers are developed at low cost with high speed and efficiency. Thus, “classical” laborious methods are no longer needed and no individual primer sets for each marker is needed. Furthermore, using the invention, many genetic markers can be identified and analyzed in a short period of time. Further analysis of the segregation of these markers in families where diseases, resistance genes, or other genes of interest are segregating as well will enable the identification of genetic markers related to the genes of interest.
[0059] In the case where lineage is in question, once the genetic markers of the individual have been determined, they can likewise be determined for the putative parents. The sets of markers (e.g., the number of repeats in a locus, the length variation of the set of amplified fragments, and so on) from an individual can then be compared with the markers of the putative parent or parents, and a determination of lineage made. In the case of the aforementioned hawk, for instance, if the number of repeats in a particular locus of the hawks' DNA do not match that of the tamed breeding putative parents, the conclusion can be drawn that the tamed breeding pair are not the parents.
[0060] The same situation arises when the question of pedigree arises. The genetic markers of the individual are compared and contrasted with those of the putative ancestors or relatives, especially parents.
[0061] In the case of gender determination, a library would first be constructed of the particular species (e.g., crocodile) with particular emphasis put on the Y chromosome. Once conserved genetic markers present on the Y chromosome are identified for the species, the DNA of the individual in question can be analyzed with the instant invention.
[0062] When the question centers around whether or not an individual of a species is the same individual previously tested (e.g., by a nation's health, agricultural, or racing authorities), the individual is tested at a different time, and the results are compared with those of the earlier analysis.
[0063] A kit of parts for use with the invention includes first and second oligonucleotide primers for performance of the first polymerase chain reaction amplification on the genomic DNA of the individual. The first oligonucleotide primer is a 5′ variation generator, starting at a repeat sequence. The second oligonucleotide primer is a 3′ fragment generator starting within such a genetic distance that amplification of the genomic DNA can be performed. The kit will also preferably include components for performing the second PCR. Such components include third and fourth oligonucleotide primers, wherein the third oligonucleotide primers is an elongated version of the 5′ variation generator, and the fourth oligonucleotide primers is an elongated version of the 3′ fragment generator. The kit of parts further also preferably includes appropriate restriction enzymes.
[0064] The invention is further explained by use of the following illustrative examples. In the examples, only a limited number of primers are shown. However, any combination of primers based on the information presented herein is considered to be using the same principles of this technology.
EXAMPLES
Example I
[heading-0065] Primer Design
[0066] Using the previously described criteria (e.g., starting at a repeat sequence and localizing the variation generator oligonucleotide primer at the 5′ site of repeat sequences, and starting within a genetic distance), the hereinafter described examples of feasible primer sequences were determined. As can be seen, the 5′ (left) end of the variation generator includes a nucleotide which is not consistent with the existing repeat pattern of the repeat sequence.
[0067] PCR 1. Variation Generator.
TTGTGTGTG (SEQ ID NO:3) ATGTGTGTG (SEQ ID NO:4) CTGTGTGTG (SEQ ID NO:5) CCACACACA (SEQ ID NO:6) GCACACACA (SEQ ID NO:7) TCACACACA (SEQ ID NO:8) TTTGTGTGTG (SEQ ID NO:9) ATTGTGTGTG (SEQ ID NO:10)
[0068] Fragment Generator.
ATGTIIIIIT (SEQ ID NO:11) ATGTCIIIIT (SEQ ID NO:12) ATGTCTIIIT (SEQ ID NO:13) TIIITGTCAG (SEQ ID NO:14) TLIIACGTCG (SEQ ID NO:15)
PCR 1. Amplification of Many Fragments
[0070] Genomic DNA taken from a sample was amplified in a first PCR at low annealing temperatures (for example, 30-65° C., but preferably lower than temperatures used at an optional second round of amplification). The previously described oligonucleotide primers were used to generate fragments. The first PCR was run under conditions where neither the fragment generator primer nor the variation generator primer alone could amplify DNA.
[heading-0071] PCR 2. Amplification of a Subset of PCR 1.
[0072] After dilution of the PCR products of the first PCR, a second PCR was conducted using the resulting fragments. This second PCR was based on the hereinafter described fragment and variation generators which, as can be seen, were elongated to enable PCR amplification at higher annealing temperatures (40-70° C.). This enabled the selection of a subset of the DNA fragments amplified in PCR 1.
[0073] Examples of the elongated primer sequences:
[0074] PCR 2. Variation Generator.
TTGTGTGTGTGTGTGTG (SEQ ID NO:16) ATGTGTGTGTGTGTGTG (SEQ ID NO:17) CTGTGTGTGTGTGTGTG (SEQ ID NO:18) CCACACACACACACACA (SEQ ID NO:19) GCACACACACACACACA (SEQ ID NO:20) TCACACACACACACACA (SEQ ID NO:21)
[0075] Fragment Generator. Six Examples are Shown:
ATGTIIIIITIIIIT (SEQ ID NO:22) ATGTCIIIITIIIITA (SEQ ID NO:23) TIIITGTCAGLIIA (SEQ ID NO:24) TIIITGTCAGIIIAA (SEQ ID NO:25) TIIIACGTCGIIIA (SEQ ID NO:26) TIIIACGTCGIIIAA (SEQ ID NO:27)
[0076] The thus amplified PCR products were digested with restriction enzymes such as BamHI or HinfI increasing the number of genetic polymorphisms detected and reducing the sizes of the DNA fragments to be analyzed.
Analysis
[0077] Analysis of the digested product was conducted on an ABI 377 sequencer (Perkin Elmer, Calif., USA). The detection on this sequencer was made possible through the use of fluorescently labeled primers; both the 5′ variation generator and the 3′ fragment generator were labeled with different dyes (such as FAM, HEX).
[0078] Analysis of the various fragment sizes was performed using the software GENESCAN™ and GENOTYPER™ (both from Perkin Elmer, Calif., USA).
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Methods and kits for analyzing a subject's genomic DNA to determine the subject's lineage. The methods comprise providing oligonucleotide primers for use in nucleic acid amplifications on a subject's genomic DNA. A first oligonucleotide primer includes a repeat sequence and at least one non-repeat nucleotide located on its 5′ end. A second oligonucleotide primer starts within an amplification-permissive genetic distance on the 3′ side of the repeat sequence in the subject's genomic DNA and may include an a-selective base, such as inosine. Additional oligonucleotide primers may be provided. The methods further comprise conducting nucleic acid amplifications on the subject's genomic DNA using the oligonucleotide primers of the invention to produce amplified DNA fragments based on repeat sequences found at the 5′ end of the subject's genomic DNA and analyzing such amplified DNA fragments to determine the length of repeat sequences found in the subject's genomic DNA.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to circuit interrupter apparatus and, more particularly, to an improved trip-actuating assembly for a molded case type circuit breaker that is designed for shipboard use and is thus subjected to mechanical shocks and vibrations of unusual severity.
2. Description of the Prior Art
Circuit breakers and related electrical generation and distribution equipment for shipboard use require special design features insofar as they must operate under adverse environmental conditions characterized by high humidity, salt water spray, high ambient temperatures, high vibration levels and high mechanical shock loads. As will be appreciated by those skilled in the art, reliable operation of the electrical equipment under such adverse operating conditions is very difficult to achieve, particularly with regard to the requirement that the equipment be able to withstand mechanical shocks and impacts. This is of special importance in the case of naval vessels that frequently experience shocks and vibrations of very high magnitude during combat when operation of the electrical system is most crucial and difficult. Various modifications to the electrical equipment intended for shipboard use have accordingly been developed over the years to render it shock-proof. However, these modifications not only increased the cost of the apparatus but complicated its manufacture on a mass production basis. Such drawbacks are of even greater significance in the design and marketing of molded case circuit breakers which are traditionally low cost, compact devices that are inherently sensitive to mechanical shocks and impacts. The need to instantly trip on high currents makes the trigger mechanism of such breakers sensitive to shock loads while the compact designs and low cost make it very difficult to provide a cost-effective reliable shock-resistant tripping mechanism in the available space within the breaker case.
A shock-resistant trip device currently used in commercial circuit breakers of the molded case type utilizes a rotatable trigger component that has a protruding latch which engages a slidable release member and holds the spring-loaded tripping mechanism of the circuit breaker in contact-closed position. The rotatable trigger component is spring biased to keep it in latched relationship with the release member and the trigger component is actuated by a magnetic trip device consisting of an electromagnet that is energized when a current overload condition is created by a fault or some other malfunction in the electric circuit being protected. The electromagnet attracts a pivoted clapper that has an end portion which engages a protruding tab-like portion of the rotatable trigger component and moves the trigger component a sufficient distance against the action of the biasing spring that the trigger latch is disengaged from the release member--thus permitting the cocked driving springs and toggle assembly of the breaker mechanism to slide the release member in a direction which allows the trip mechanism to open the breaker contacts and quickly interrupt the circuit. In accordance with standard design practice, the circuit breaker is restored to contact-closed position by a manual or motor operated closing sequence which extends or compresses suitable springs in the trip mechanism and stores the energy required for the next trip operation. The springs are prevented from tripping the circuit breaker by the slidable release member which, in turn, is controlled by the rotatable trigger component and its latch.
While such shock-resistant tripping mechanisms are in widespread use in commercial type molded case circuit breakers and function satisfactorily, they are not suitable for use in circuit breakers installed on naval vessels since the severe shock loads encountered aboard such vessels are sufficient to actuate the triggering mechanism and cause the breaker to be tripped from mechanical as well as electrical loads. Since the shock loads are most intense during combat the accidental tripping of circuit breakers under such conditions is intolerable since it deprives the ship of electrical power when it is most needed.
In order to make the aforementioned prior art tripping mechanism less sensitive to mechanical shocks and impacts inertia wheels were added to the mechanism to prevent the trigger component from reacting to high frequency mechanical loads. The inertia wheels were coupled to the rotatable trigger component in such a way that they prevented the rapid acceleration of the trigger component and thus helped to isolate the trigger component from impulse-type shock loads. While this arrangement improved the shock tolerance of the tripping mechanism, it was not "fail safe" and it is relatively ineffective for high amplitude, low frequency shock loadings of the kind that would be encountered aboard naval vessels.
It would, accordingly, be very advantageous from both a functional and marketing standpoint if a circuit breaker could be provided with a shock-proof triggering device that was compact, reliable, low in cost and geometrically flexible enough to be easily adapted to the available space in the molded case breakers now being manufactured and marketed and thus produce circuit breakers of this type that have the operational stability and ruggedness required for shipboard use and similar rough service applications.
SUMMARY OF THE INVENTION
The present invention provides the foregoing manufacturing, operational and marketing advantages by utilizing a trip-actuating mechanism that decouples the mechanical latch release mechanism from external shock loads while providing very rapid response to an electrical overload signal so that the circuit breaker will be tripped in a reliable and positive manner only when it is necessary to interrupt the electrical circuit due to a fault or other potentially dangerous malfunction. Such decoupling "desensitizes" the mechanical trip mechanism from the external shock loadings to which the circuit breaker is subjected during use and, in accordance with the present invention, is accomplished by means of a trip-actuating assembly having a unique shock-proof lock mechanism that insures that the circuit breaker is maintained in spring-loaded contact-closed NO-TRIP condition until a current overload signal is received that releases the lock mechanism and trip-actuating assembly and rapidly initiates the trip sequence. The lock mechanism utilizes either a rotating or reciprocally-movable magnetic keeper which is held in "lock" position by a spring and is moved to "unlock" position for breaker tripping by a magnetic field that is generated by an electromagnet.
In the disclosed embodiments the electromagnet comprises a solenoid which also serves as the motive source which propels a plunger into engagement with the pivoted trip bar of the circuit breaker, thus releasing the breaker latch mechanism and triggering the spring-loaded trip mechanism with resultant rapid opening of the breaker contacts.
In accordance with one form of the invention the plunger comprises a longitudinally extending appendage of the movable core of the solenoid and locking of the solenoid in NO-TRIP position is effected by a spring-biased keeper of magnetic material that is movably mounted within an opening of a metal yoke-chassis that extends around and supports the solenoid. The yoke-chassis constitutes a magnetic circuit that concentrates magnetic flux in the opening, when the solenoid is energized, which automatically retracts the keeper from locking engagement with the core member of the energized solenoid and thus permits the solenoid core member and its plunger appendage to be rapidly propelled toward and strike the trip bar of the circuit breaker.
In an alternative embodiment, the locking means comprises a non-magnetic stop which engages a protruding lobe element of the solenoid core member when the latter is in its dormant NO-TRIP mode. When a current overload condition in the circuit is sensed and the solenoid is energized by a suitable solid-state control circuit provided within the breaker housing, the solenoid core member automatically rotates through a predetermined angle until it is aligned with a magnetic pole piece provided on the yoke structure. Such rotation permits the lobed portion of the core member to slip over and pass the stop member with resultant release of the core member and plunger from their locked position. A suitable spring means automatically returns the lobed portion of the solenoid core member to its locked NO-TRIP position on the stop when the solenoid is deenergized after the circuit breaker has been tripped and the breaker contacts opened.
BRIEF DESCRIPTION OF THE DRAWINGS
A better understanding of the invention will be obtained from the exemplary embodiments shown in the accompanying drawings, wherein:
FIG. 1 is a sectional view through the center pole portion of a three-pole molded case circuit breaker of the low-voltage type which incorporates the improved trip-actuating assembly of the present invention;
FIG. 2 is an enlarged top plan view of the trip-actuating assembly employed in the circuit breaker shown in FIG. 1;
FIG. 3 is a sectional view of the trip-actuating assembly along line III--III of FIG. 2, the solenoid core member and its plunger appendage as well as the rotatable locking component being shown in full lines for illustrative purposes;
FIG. 4 is another sectional view of the trip-actuating assembly along line IV--IV of FIG. 3;
FIG. 5 is a schematic of the control and power circuit used in the circuit breaker shown in FIG. 1 for energizing the trip solenoid and plunger in response to circuit overload conditions;
FIG. 6 is a cross-sectional view of an alternative trip-actuating assembly that utilizes a reciprocally-movable locking member;
FIG. 6A is a fragmentary view of the alternative assembly shown in FIG. 6 with the locking member in retracted position;
FIG. 7 is a pictorial exploded view of another alternative trip-actuating assembly which employs a rotary key-fit arrangement for mechanically locking and releasing the plunger component of the solenoid;
FIGS. 8, 9 and 10 are cross-sectional views of the alternative trip-actuating assembly shown in FIG. 7, taken along the correspondingly-numbered lines of this Figure;
FIG. 11 is a perspective view of the trip-actuating assembly of FIG. 7 in its unlocked released condition;
FIG. 12 is a schematic representation of the magnetic circuit employed in the FIGS. 7-11 embodiment and the manner in which the lobed portion of the actuator core is magnetically rotated into its unlocked released position;
FIG. 13 is a sectional view of still another alternative embodiment of the trip-actuating assembly according to the present invention which utilizes the rotative key-fit locking and release arrangement employed in the FIGS. 7-11 embodiment; and
FIG. 14 is a cross-sectional view of this alternative embodiment, along line XIV--XIV of FIG. 13.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
While the improved trip-actuating assembly of the present invention can be employed in various kinds of circuit interrupting apparatus that are used in environments which subject the apparatus to vibration and mechanical shocks, it is particularly adapted for use in conjunction with low voltage circuit breakers of the molded case type that are employed aboard ships and naval vessels that require circuit breakers which will not be inadvertently tripped in rough seas or under combat conditions and will operate reliably in such adverse environments.
In FIG. 1 there is shown a molded case three-pole circuit breaker 10 which comprises a housing 12 that is fabricated from a suitable insulative material and includes a base component 14 and a removable cover component 16. Insulating barrier means 18 within the housing 12 defines, in conjunction with the base 14 and cover 16, three adjacent compartments that contain the three pole units. One of the pole units is shown in FIG. 1 and consists of the usual stationary contact 17 and a movable contact 18 that are located (when in their closed position as shown) within the confines of an arc chute assembly 20 which defines an arc extinguishing chamber. The arc chute assembly 20 comprises the usual series of vertically stacked arc chute plates 21 that are designed to divide the arc into small segments and rapidly extinguish it when the circuit breaker 10 is tripped and the contacts 17, 18 are suddenly opened. The stationary contact 17 is mounted on a rigid conductor 22 that extends through the end wall of the housing 12 and is connected to a suitable terminal block 23. The movable contact 18 is mounted on a contact arm 19 that is pivotally supported within the base component 14 and connected to a second rigid conductor 24 by a flexible conductor 25. The end of rigid conductor 24 extends through the other end wall of the base component 14 and is connected to a second terminal block 26. Each of the terminal blocks 23, 26 include a lock screw 27 that is adapted to engage and tightly clamp cable conductors (not shown) that are inserted into the terminal blocks.
An operating mechanism 28 (which is common to and operates each of the three pole units) is provided for simultaneously actuating the three movable contacts in each of the three circuit breaker compartments between their open and closed positions. The operating mechanism 28 includes the usual toggle links 29, 30 that are pivotally connected together by a knee pivot. Toggle link 30 is pivotally attached to the movable contact arm 19 and the interaction of the various parts of the operating mechanism 28 is such that the movable contact arm 19 and its contact 18 are rapidly swung upwardly away from the stationary contact 17 by the action of a pair of springs 31, 32 when the circuit breaker 10 is tripped. The operating lever of the toggle linkage is fastened to an insulating handle 33 which extends through a suitable opening in the cover 16 and permits the operating mechanism 28 to be restored to spring-loaded contact-closed condition after the breaker 10 has been tripped. The operating mechanism 28 is held in its "contact-closed" condition against the action of the power springs 31, 32 by a trip latch 34 that is captured by a pivoted trip bar 35 which is held in such relationship with the latch 34 by a suitable spring 36.
In accordance with the present invention, the triggering of the trip mechanism is achieved by a trip-actuating assembly 38 that comprises a solenoid 40 which is energized in response to a current overload or fault condition that is sensed by suitable means and transmitted to a solid-state control and power circuit module 42 connected to the solenoid 40 by a pair of conductors 43. As illustrated in FIG. 1, the trip-actuating assembly 38 is very compact and is mounted within the base portion 14 of the circuit breaker 10 in close proximity to the trip bar 35 so that a protruding actuator member, such as a rod-like plunger 44, is positioned to engage and push the lower end of the trip bar 35 a sufficient distance to release the trip latch 34 and initiate the breaker-tripping sequence when the solenoid 40 is energized. In this particular embodiment, the current-overload sensing means comprises a current transformer 45 that is coupled to the main conductor 24 and is connected by suitable wires 46 to the solid state control circuit module 42. The structural details of the trip-actuating assembly 38 and the manner in which the solenoid-powered plunger 44 is mechanically locked in NO-TRIP position despite the intensity of the physical shocks and vibration experienced by the circuit breaker 10 during use is illustrated in FIGS. 2-4 and will now be described.
As shown in FIG. 2 and more particularly in FIG. 3, the trip-actuating assembly 38 comprises a generally rectangular structure of compact size that is formed by housing the solenoid coil winding 40 and its movable core member 41 in a generally U-shaped yoke 48 of magnetic sheet metal (such as steel) that has a top wall 49 and two upstanding end walls 50, 51 and serves as a support chassis. The core member 41 is of cylindrical shape and is reciprocally movable within the bore cavity of the solenoid coil winding 40 and extends through a suitable aperture in the end wall 50. The other end wall 51 is also provided with an opening that receives a circular plug 52 of magnetic or non-magnetic material that has a central bore which slidingly accommodates the rod-like actuator plunger 44 which is integral with and constitutes an axially extending appendage of the solenoid core member 41. The solenoid coil 40 is held in place within the yoke-chassis 48 by a bottom wall 53 of non-magnetic material (such as a suitable plastic) that is press-fitted over lugs 54 that extend from the end walls 50, 51 and a central partition 55 of non-magnetic material that prevents the solenoid coil 40 from shifting laterally within the yoke-chassis 48. A collar 56 of suitable non-magnetic material (such as aluminum) is attached to the solenoid core member 41 and is pressed against the partition 55 by a compression spring 57 that is disposed between end wall 51 and the collar 56. Compression spring 57 accordingly serves as a return spring that automatically resets the solenoid core member 41 and plunger 44 in their dormant NO-TRIP positions shown in full lines in FIGS. 2 and 3.
As will also be noted in FIG. 3, the end face 47 of the solenoid core member 41 is spaced a predetermined distance from the inner face of the plug 52 so that the core member 41, its attached collar 56 and the protruding plunger 44 are reciprocally movable as a unit relative to the solenoid coil 40 and yoke-chassis 48, as indicated by the double-ended arrow in FIG. 3 and the broken-line depiction of the ends of the plunger 44 and core member 41 in FIGS. 2 and 3. The distance traveled by the plunger 44 as it moves in reciprocating fashion along with the solenoid core member 41 and collar 56 is sufficient to swing the pivoted trip bar 35 of the circuit breaker 10 a distance such that it releases the latch 34 of the breaker 10 and initiates the trip sequence. The solenoid core member 41 and its plunger actuator 44 are accordingly reciprocally movable between a TRIP position (depicted by the broken line portions of FIGS. 2 and 3) and a dormant NO-TRIP position (shown by the full line portions of these Figures).
An important feature of the invention is the manner in which the solenoid core member 41 and its plunger actuator 44 are mechanically locked in their dormant NO-TRIP position and are automatically released from such position when the solenoid coil 40 is energized in response to a sensed current overload condition in the electrical circuit being protected. This is achieved by a rotatable member of magnetic material (steel for example) such as a flapper-like keeper 58 of elongated cross-section that is held in an opening 59 in the top wall 49 of the yoke-chassis 48 by a suitably shaped support structure 60 of non-magnetic material that is fastened to the top wall 49 by fasteners 61. The keeper 58 is rotatably coupled (as shown in FIG. 4) to the support structure 60 by axle shafts 62 that extend from the ends of the keeper 58 and are disposed in apertures provided in flanges 63 that extend downwardly from the top wall of the support structure 60 into the opening 59 in the yoke-chassis 48. The keeper 58 is thus freely rotatable within the opening 59 and is of sufficient width that a side-edge portion extends toward and serves as a stop for the peripheral edge portion of the solenoid collar 56 when the solenoid coil 40 is deenergized and the keeper 58 is tilted downwardly toward the collar 56 with the opposite side-edge portion of the keeper in contact with the adjacent edge of the support structure 60. This tilted NO-TRIP position of the keeper 58 and the resulting mechanical interlock which it provides for the solenoid collar 56 and the attached core member 41 and plunger 44 is shown in full lines in FIG. 3.
A torsion spring 64 disposed around one of the axle shafts 62 of the keeper 58 and held in place by a pin 65 on the keeper 58 and the adjacent edge of the support structure 60 applies a bias to the keeper 58 which tilts it downwardly into its solenoid-locking position (shown in FIGS. 2-4) when the solenoid coil 40 is deenergized and the core member 41, plunger 44 and collar 56 are disposed in their NO-TRIP positions, illustrated by the full-line portions of FIGS. 2 and 3.
Automatic release of the solenoid core member 41 and plunger 44 from their locked NO-TRIP positions is achieved in accordance with the invention by the magnetic flux which is produced in the yoke opening 59 by the energized solenoid coil 40 and the yoke-chassis 48 which serves as a magnetic circuit means. Since the magnetic flux spans the yoke opening 59 along a straight path it causes the magnetic keeper 58 to rotate to its broken-line position (shown in FIG. 3) against the action of the spring 64 until it is automatically aligned with the plane defined by the top wall 49 of the yoke-chassis 48. Such magnetically induced rotation of the keeper 48 releases the core member 41, plunger 44 and collar 56 from their locked NO-TRIP positions and permits the energized solenoid coil 40 to rapidly propel the core member 41 and plunger 44 into their TRIP positions depicted by the broken-line portions of FIGS. 2 and 3. Once the solenoid coil 40 is energized the rotation of the keeper 58 and the propulsion of the unlocked core member 41 and plunger 44 to their TRIP positions occur simultaneously so that the trip bar 35 of the circuit breaker 15 is actuated and initiates the trip sequence within a few milliseconds after the current overload condition in the circuit is sensed and the solenoid coil 40 is energized.
After the circuit breaker 10 has been tripped and the solenoid coil 40 is deenergized, the compression spring the solenoid coil 40 is deenergized, the compression spring 57 automatically restores the core member 41, plunger 44 and collar 56 to their dormant NO-TRIP positions and the biasing spring 64 automatically tilts the keeper 58 downwardly through the yoke opening 59 into interlocking relationship with the peripheral edge of the solenoid collar 56. The trip-actuator assembly 38 is accordingly restored to its original NO-TRIP condition and is automatically reset for another trip-actuating operation.
In accordance with a preferred embodiment of the invention, the U-shaped yoke-chassis 48 is fabricated from sheet steel to provide an efficient magnetic circuit means and the central partition 55 and keeper-support structure 60, as well as its flanges 63, are fabricated from aluminum or other non-magnetic metal. The bottom wall 53 of the assembly 38 can be fabricated from a suitable rigid plastic.
In the FIG. 1 embodiment the circuit breaker 10 is tripped on power which is derived from the current transformer 45 that is coupled to the main conductor 24 of the breaker which is connected to the electrical circuit being protected. The output of the current transformer 45 is fed into a suitable electronic sensing circuit which produces a trip signal that is fed into a trigger transistor that is in series with and supplies sufficient energizing current to the solenoid coil 40 derived from the transformer action and the fault current. The electronic sensing circuit and the trigger transistor comprise parts of the solid state control module 42 that is mounted within the circuit breaker housing 12 as illustrated in FIG. 1.
An alternative solid state circuit 67 for energizing the solenoid coil 40 in response to a detected current overload condition in the electrical circuit is shown in FIG. 5. The circuit 67 would be energized by tapping it into the internal main conductors 22, 24 of the circuit breaker 10 or by connecting the circuit terminals L 1 and L 2 to a separate power supply provided in the well-known manner for operation of the circuit breaker 10. As illustrated, the solenoid winding 40 is connected in series with a rectifier 68, a limiting resistor 69 and a trigger transistor 70 that is fed with a trip signal generated by a suitable sensor (not shown). An energy storage capacitor 71 is connected in parallel with the solenoid winding 40 and also in parallel with another resistor 72, a Zener diode 73 and a rectifier 74 which limits the voltage on the capacitor 71. All of the aforesaid components, with the exception of the solenoid winding 40, constitute parts of the solid state module 42 that is mounted within the circuit breaker housing 12 as illustrated in FIG. 1.
ALTERNATIVE TRIP-ACTUATOR EMBODIMENT (FIGS. 6 and 6A)
An alternative trip-actuating assembly 38a which employs a different mode of mechanically locking and releasing the solenoid core member and actuator-plunger is illustrated in FIGS. 6 and 6A and will now be described.
As shown in FIG. 6, the trip-actuating assembly 38a is basically of the same construction as the FIGS. 2-4 embodiment in that it comprises a yoke-chassis 48a of magnetic material that has a top wall 49a, end walls 50a and 51a and an insulative bottom wall 53a which form a housing that encloses and supports the solenoid winding 40a and its reciprocally movable core member 41a and depending plunger 44a. The annular collar 56a extends laterally from the core member 41a and has shank portion 74 of reduced diameter that is seated against the central partition 55a by the action of the return spring 57a that is disposed between the collar 56a and end wall 51a of the yoke-chassis 48a. The shank portion 74 thus acts as a stop for the core member 41a and plunger 44a when the trip-actuating assembly 38a is in its dormant NO-TRIP mode shown in FIG. 6. The plunger 44a extends through a bushing 52a of suitable material (either magnetic or non-magnetic) that is fitted into a suitable opening in the end wall 51a and provides a seat for the associated end of the return spring 57a and end face 47a of the core member 41a.
In contrast to the previous embodiment, the solenoid core member 41a and its plunger 44a are locked in their NO-TRIP positions by a spindle-like component such as a keeper 58a of magnetic material that is reciprocally movable in a lateral direction toward and away from the solenoid collar 56a and is held in such relationship by an apertured plug 75 of suitable non-magnetic material that is secured in an opening provided in the top wall 49a of the yoke-chassis 48a. The keeper 58a has an enlarged head portion that serves as a pawl with a notched and tapered profile. A small compression spring 76 provided between the end of the keeper 58a and top wall of the non-magnetic support structure 60a pushes the keeper 58a toward the solenoid core member 41a when the solenoid coil 40a is deenergized so that the notched tip of the keeper 58a extends beyond and thus serves as a mechanical interlock for the peripheral edge of the solenoid collar 56a, as shown in FIG. 6. This mechanical interlock ensures that the trip-actuating assembly 38a will remain in its dormant NO-TRIP mode despite severe mechanical shock and vibration experienced by the circuit breaker in which it is used.
When a current overload condition is detected by the control module within the circuit breaker and the solenoid coil 40a is energized, the magnetic circuit provided by the yoke-chassis 48a produces a magnetic flux in the yoke opening fitted with the non-magnetic plug 75 with the result that the pawl-shaped keeper 58a is attracted toward the top wall 49a of the yoke-chassis 48a against the action of the compression spring 76 until the transverse bar portion of the keeper 58a contacts and is seated against the plug 75, as shown in 6A. This permits the solenoid collar 56a to clear the notched tip of the retracted keeper 58a, thus releasing the solenoid core member 41a, collar 56a and plunger 44a from their locked NO-TRIP positions. The energized solenoid coil 40a simultaneously causes the released core member 41a to be rapidly propelled toward the end wall 51a of the yoke-chassis 48a until the end 47a of the core member 41a strikes and is seated against the bushing 52a. The protruding tip of the plunger 44a is accordingly also rapidly advanced and swings the pivoted trip bar of the circuit breaker the distance required to release the trip latch and initiate the breaker-tripping sequence.
After the circuit breaker has been tripped and the circuit interrupted, the solenoid coil 40a is deenergized--thus permitting the compression spring 57a to return the core member 41a and plunger 44a to their NO-TRIP positions. The resulting collapse of the magnetic field also releases the keeper 58a and permits it to be automatically returned to its mechanically interlocked relationship with the peripheral edge of the solenoid collar 56a by the action of spring 76. The actuating assembly 38a is thus automatically reset for the next trip operation.
ALTERNATIVE LOCKING MEANS FOR ACTUATOR (FIGS. 7-12)
An alternative rotative "key" arrangement for mechanically locking a trip actuator in dormant NO-TRIP position and then automatically releasing it with electromagnetic forces generated in response to a current overload condition in accordance with the invention is illustrated in FIGS. 7-12.
As shown in FIG. 7, the trip-actuator assembly 38b in accordance with this embodiment comprises a stationary cylindrical housing 78 of non-magnetic material having a specially shaped passageway for receiving the movable plunger component 79 of the assembly. As will be noted from the cross-sectional view of the housing 78 shown in FIG. 9, the end portion of the housing 78 that receives the plunger component 79 defines a cylindrical passageway which is dimensioned to slidingly receive a pair of arcuate lobe segments 80, 81 that laterally extend in opposite directions from the plunger 79 (FIG. 8) and are fabricated from magnetic material. Lobe segment 81 has an axially extending lug 82 and the plunger 79 is of cylindrical rod-like shape and provided with a torsion spring 83. The length of the plunger 79 relative to the tubular housing 78 is such that the tip 84 of the plunger 79 extends beyond the housing 78 when the actuator 38b is in its released TRIP mode (shown in FIG. 11).
As illustrated in the cross-sectional view through the medial portion of the housing 78 illustrated in FIG. 10, this part of the housing is configured to provide two laterally extending passageways 85, 86 and a central cylindrical passageway 87 that are shaped and dimensioned to slidingly accommodate in key-lock fashion the lobed segments 80, 81 and end portion 84 of the plunger 79. The plunger 79 is accordingly freely rotatable when its lobed portion is located within the cylindrical end portion of the housing 78 and it is only movable along the housing 78 in an axial direction when the plunger 79 is rotated through an angle such that the lobe segments 80, 81 mate with and enter the passageways 85, 86 of the housing. Housing passageway 85 is contoured to provide a recess 88 shaped and oriented to receive the lug portion 82 of the plunger lobe 81 and thus serve as a stop which controls the axial movement of the plunger 79.
The torsion spring 83 is attached to the end portion 84 of the plunger 79 and to the wall of the stationary cylindrical housing 78 (after the end 84 of the plunger 79 has been inserted through the cylindrical passageway 87 of the housing). The torsion spring 83 acts in a direction which rotates the plunger 79 into its mechanically locked NO-TRIP position--that is, with the plunger lobes 80, 81 rotationally displaced from the mating passageways 85, 86 of the housing 78. Suitable stops (not shown) on the inner wall surface of the housing 78 prevent the plunger 79 from being rotated by the torsion spring 83 beyond a predetermined angle selected to unlock the plunger. Rotation of the plunger 79 through the aforesaid angle required to align the lobes 80, 81 with the housing passageways 85, 86 and thus effect the release and axial movement of the plunger 79 required to trip the circuit breaker is achieved by positioning a small electromagnet (not shown) adjacent the portion of the stationary housing 78 that contains the lobes 80, 81. This electromagnet is powered by solid-state circuit module provided within the circuit breaker (or by the incoming line current) and is so oriented that its magnetic field rotates the lobed portion of the plunger 79 through the aforesaid angle.
A schematic representation of the manner in which an electromagnet 90 is employed to apply the necessary torque to the rotatable plunger 79 required to align the magnetic lobes 80, 81 with the matching passageways 85, 86 in the stationary housing 78 and release the trip-actuator 38b is shown in FIG. 12. The electromagnet 90 comprises the usual coil 91 and a steel yoke 92 that provides a flux path and has pole pieces 93, 94 that are located adjacent the lobed portion of the plunger 79 which is also fabricated from steel. When the electromagnet 90 is energized, the magnetic flux in the air gaps separating the pole pieces 93, 94 from the lobes 80, 81 of the plunger 79 produces a torque which causes the plunger 79 to rotate in the manner indicated by the arrows until the lobes 80, 81 are aligned with the pole pieces 93, 94. The magnetically-induced rotational force applied to the lobed portion of the plunger 79 by the energized electromagnet 90 is sufficient to overcome the counteracting torsional force of the spring 83 (FIGS. 7 and 11) and thus rotate the plunger 79 into its keyed unlocked position within housing 78.
The amount of torque developed by the interaction of the lobed portion of the steel plunger 79 and the electromagnet 90 is proportional to the current flowing through the coil 91 which, in turn, is directly proportional to the level of current flowing through the breaker. This arrangement would accordingly be identical to that employed in a conventional magnetic trip breaker. If desired, a suitable bimetallic heater element can also be provided within the circuit breaker to apply a rotative force to the plunger 79 sufficient to move it into its keyed unlocked position. If such a bimetallic heater element were combined with the electromagnet 90 the resulting arrangement would provide a breaker that would trip on either a thermal or magnetic signal.
ROTATIVE TRIP-ACTUATING EMBODIMENT (FIGS. 13-14)
A solenoid powered trip-actuating assembly 38c which embodies a variation of the rotative locking and key-releasing concepts of the FIGS. 7-12 embodiment is shown in FIGS. 13 and 14.
As will be noted in FIG. 13, the trip-actuating assembly 38c comprises a solenoid winding 40c, a reciprocally-movable core member 41c, plunger appendage 44c, central partition 55c and a return compression spring 57c that are disposed within a magnetic yoke-chassis 48c in accordance with the basic structural design employed in the previously described FIGS. 2-6 embodiments. When the actuating assembly 38c is in locked NO-TRIP condition shown in FIGS. 13 and 14, a pair of laterally-extending magnetic lobes 95, 96 on the solenoid core member 41c rest upon a pair of longitudinally extending stops 97, 98 of non-magnetic material that are secured to the end wall 51c of the yoke-chassis 48c. As shown in FIG. 14, in accordance with this embodiment the yoke-chassis 48c includes a pair of side walls 99, 100 of magnetic material that are provided with a pair of pole pieces 101, 102 which are displaced 90° from the stops 97, 98.
When the solenoid coil 40c is energized by the solid-state circuit module within the circuit breaker in response to a current-overload condition the magnetic flux produced in the gap separating the pole pieces 101, 102 by the yoke-chassis 48c generates a torque which causes the lobed portion of the core member 41c to rotate (in the manner depicted by the arrows in FIG. 14) until the lobes 95, 96 are aligned with the pole pieces 101, 102 (as shown by the broken-line portions of FIG. 14). When the lobes 95, 96 are rotated through an angle sufficient to slide off and clear the stops 97, 98, the core member 41c will automatically be unlocked and then be simultaneously propelled by the electromotive force of the energized coil 40c in an axial direction through a distance such that the protruding tip of the plunger 44c hits and actuates the trip bar of the circuit breaker.
When the solenoid coil 40c is deenergized after the tripping sequence, the return spring 57c moves the core member 41c and plunger 44c to their original NO-TRIP position. The return spring 57c is attached to the solenoid collar 56c and to the end wall 51c of the yoke-chassis 48c and is coiled in such a manner that it also applies the required rotational force to the core member 41c and plunger 44c to return the solenoid lobes 95, 96 to their locked positions on top of the respective stops 97, 98.
In contrast to the FIGS. 2-6 embodiments, both the top wall 49c and bottom wall 53c of the yoke-chassis 48c are made of steel or ther suitable magnetic material to provide an efficient magnetic circuit from the solenoid coil 40c to the pole pieces 101, 102.
To minimize friction, the end faces of the lobes 95, 96 and the surfaces of the stop abutments 97, 98 which are in sliding contact are substantially flat and smooth.
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The trip mechanism of a molded case type circuit breaker is actuated by a plunger that is integral with and axially extends from the end of a reciprocally-movable core member of a solenoid mounted within the breaker housing. The free end of the plunger strikes the trip bar of the breaker when the solenoid is energized in response to a current overload condition in the circuit being protected. The solenoid core member and plunger are mechanically locked in NO-TRIP position by spring-biased keeper means that is automatically released from its "lock" position by the magnetic field generated by the solenoid coil when it is energized. A spring automatically resets the trip-actuating assembly when the current-overload condition has been corrected and the solenoid coil is deenergized. The trip-actuating assembly is not only compact, reliable and inexpensive but is inherently adapted to withstand severe mechanical shocks and impacts, such as those encountered aboard naval vessels, and is thus especially suited for use in circuit breakers that will be employed to protect electrical circuits and equipment subjected to such rough service conditions.
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CROSS REFERENCE TO CO-PENDING APPLICATION
[0001] This application claims priority benefit to the Feb. 10, 2014 filing date of provisional patent application Ser. No. 61 / 937 , 880 for ROAMING TRANSPORT DISTRIBUTION MANAGEMENT SYSTEM and to the Sep. 19, 2013 filing date of provisional patent application Ser. No. 61/879,737 for ROAMING TRANSPORT DISTRIBUTION MANAGEMENT SYSTEM, and is a continuation-in- part of co-pending U.S. patent application Ser. No. 13/563,618, filed on Jul. 31, 2012 for URBAN TRANSPORTATION SYSTEM AND METHOD, assigned to the assignee of the present application, which claims priority to U.S. provisional patent application Ser. No. 61/626,123 filed on Sep. 20, 2011, the contents of all which are incorporated herein in their entirety.
BACKGROUND
[0002] The present apparatus and method relate to urban transportation systems.
[0003] U.S. Patent Publication 2013/0073327 discloses an urban transportation system and method, which provides flexible, door-to-door transportation service between customers within a service area surrounding a node of a station of an urban transportation system, such as a train station, subway station, etc.
[0004] In response to a customer request, a transport within a defined service area travels to the location of the customer and then transports the customer between the pick-up location and the node in the transportation system which is the central hub in the service zone. The transport service request instructions are dynamically determined in real time with respect to the customer pick-up location, the current location of the transport, and a predetermined maximum allowable travel time between the customer pick-up and drop-off at the node.
[0005] The predetermined travel time may be calculated for a transport using the time that the customer reaches the transit node starting with the time of the pick-up request from the customer until the time the customer reaches the transit node or from the time the customer is picked up and dropped off at the node. Either time periods define the predetermined time period essential to efficient operation of the transit model. For example, if a 15 minute predetermined time period is selected for operation of the transit system, and the first time period calculation described above is utilized then the transit system must respond to a pick-up request from a customer by directing a transport at a second location within the service area surrounding node to the location of the customer, pick-up the customer and then travel by a flexible, real time determined route to the node so that the customer reaches the node within 15 minutes of initiating a pick-up request.
SUMMARY
[0006] A roaming transport distribution apparatus and method for servicing customer requests for transportation of customers within a service zone.
[0007] The method includes operating a plurality of transports in a first service zone for transporting customers within the first service zone to and from a first hub and receiving a service request from a first customer at a first location in the first service zone for transportation of the first customer to and/or from the first hub.
[0008] Next, the method locates one transport of the plurality of transports in the first service zone to answer the service request based on one or more of the location of the first customer, the location of the transport, the distance between the two locations, a travel time of the transport from its location to the customer location, and a travel time of the transport with the picked-up customer from the first location to the first hub or from the first hub to another customer destination.
[0009] A system manager sends a communication to a transport with a location to pick up the first customer. The system manager further sends a communication to the transport of a travel route from pick up location of the first customer to a customer drop-off location.
[0010] The system manager directs the plurality of transports in the first service zone to unequally distributed locations with exclusive coverage areas of the transports which are disposed in a non-overlapping arrangement within the first service zone.
[0011] The method can further unequally distribute all of the transports in the first service zone based on one of population density, historic request density and traffic conditions, creating an exclusive coverage service area about each transport in the first service zone, where the coverage service areas are disposed in a dynamic arrangement with adjacent exclusive transport service sub-areas, and directing the plurality of transports in the first service zone to unevenly distributed locations with non-overlapping coverage areas.
[0012] According to the method, after one transport picks up the first customer at the first location, the one transport is removed from roaming in the first service zone. The method relocates the position of at least one other transport in the service zone so that the coverage areas of all of the transports are disposed in a dynamic arrangement to insure the predetermined transit time is met for all areas in the service zone.
[0013] In the method, after the one transport picks up the first customer at the first location and the first transport is removed from roaming in the first service zone, the size and/or location of the coverage areas of at least one of the transports in the service zone is varied to meet the predetermined transit time at all locations within the first service zone.
[0014] The method further includes choosing the one transport of the plurality of transports to answer a service request where the location of the transport relative to a customer issuing a service request satisfies one of a minimum wait time of customer pick-up and a less than maximum transit time of the customer to the customer destination.
[0015] The method further includes reinserting a new transport into the first service zone and redistributing all of the coverage areas of the plurality of transports in the first service zone to insure distribution of the coverage areas in the first service zone without overlap.
[0016] The roaming transportation distribution apparatus includes a system manager choosing the one transport of the plurality of transports to answer a service request where the location of the transport relative to a customer issuing a service request satisfies one of a minimum wait time for customer pick-up and less than a maximum transit time of the customer to the customer destination.
[0017] The system manager wirelessly communicates travel information to each of the transports to optimize travel of a transport from a current location of the transport to a customer and/or from a customer pick-up location to a customer drop-off destination.
[0018] The system manager in response to removal of a transport from the plurality of transports in a first service zone when the transport is answering a service request, issues new coordinate information by wireless communication to at least one other transport in the first service zone to redistribute the remaining plurality of transports in the first service zone.
[0019] The system manager, executing program instructions, based on current coordinate locations of the plurality of transports remaining in roaming in the first service zone, to vary a size of the coverage area of at least one of the remaining transports to meet transport transit times associated with responses to customer requests
BRIEF DESCRIPTION OF THE DRAWING
[0020] The various features, advantages, and other uses of the present apparatus and method will become more apparent by referring to the following detailed description and drawing in which:
[0021] FIG. 1 is a conceptual diagram illustrating a transportation system providing transportation service to a service zone around a transit mode;
[0022] FIG. 2 is a diagram showing the delivery of a passenger from a pick-up location in one service area to a destination location in another service area according to the method and apparatus;
[0023] FIG. 3 is a diagram illustrating the use of the present method and apparatus over multiple service areas;
[0024] FIG. 4 is a schematic diagram illustrating the components of the apparatus for implementing the method;
[0025] FIG. 5 is a blocked diagram showing the construction of the system manager;
[0026] FIGS. 6 , 7 , 8 , and 9 A- 9 D are pictorial representations illustrating the operation of the present apparatus and method to implement distribution of the transport transports within a service area;
[0027] FIG. 10 is a pictorial representation of the present method and apparatus implemented in multiple overlapping service areas;
[0028] FIG. 11 is a flowchart depicting the operation of the apparatus and method for an inbound request; and
[0029] FIGS. 12A and 12B are flow diagrams depicting the operation of the apparatus and method for an outbound request.
DETAILED DESCRIPTION
[0030] FIG. 1 depicts a service zone 100 which surrounds a centrally located node 102 , which may be a train or subway station or a bus stop in an urban transit or transportation system, or any other transportation system having defined locations for transport vehicles to pick-up and drop off passengers. The node 102 also acts as the central hub 102 of the service zone 100 .
[0031] The service zone 100 is illustrated with multiple sub zones has service transports distributed through each of the sub zones to minimize travel time between the location of the transport, a pick-up location of a customer requesting a pick-up and the delivery of the customer to the end drop off destination. It is desirable to provide improvement to such a urban transportation system so as to minimize pick up time as well as meeting the maximum travel time to the drop off location.
[0032] The service zone 100 may be a single large defined area, with a circular service zone shown by way of example only. It will be understood that the service zone 100 may take other shapes, such as polygonal, triangular, oval, etc., depending upon geographic features surrounding the node 102 , population density, service request density and other factors.
[0033] Further, the service zone 100 is illustrated with concentric sub-zones 101 , 103 , 105 and 107 , with four sub-zones shown in FIG. 1 spaced at one mile, two mile, three mile, and four mile radii, respectively, from the central hub 102 .
[0034] Service transports (hereafter “transports”) 104 , 106 may be distributed throughout the sub-zones of the larger service zone 100 to minimize travel time between the location of the transport 104 and a pick up location 111 of a customer 110 initiating a pick-up service request. The transports 104 , 106 may be any type of transport, such as a car, minivan, bus, SUV, etc.
[0035] Each transport 104 , 106 , etc., has global positioning system (GPS) capability. A GPS transceiver can be mounted in each transport 104 , 106 for communication with the global positioning satellite network to provide a central system manager with the current GPS coordinates of each transport 104 , 106 .
[0036] Each transport 104 and 106 also has wireless communication capability with the system manager. The wireless communication capability can include a cellular network transmitter and receiver mounted in the vehicle for communication between the transport 104 , 106 and the system manager via a cellular telephone network. Such cellular wireless communication can also be implemented by using the driver's cellular telephone for direct communication via the cellular network with the system manager or through the cellular telephone system of the transport 104 , 106 .
[0037] Other forms of wireless communication, including satellite communication, etc., can also be employed to transfer data between each transport 104 , 106 and the central manager.
[0038] The overall size of the service zone 100 is selected so that predetermined transit time, such as 15 minutes for example, can be met for all customer pick-up requests at any location within the service zone 100 to the drop off destination.
[0039] Thus, it is possible that, depending upon population density and service request density, as well as geographic features, one service zone 100 of a plurality of service zones shown in FIG. 3 , can have larger or smaller overall dimensions than that of surrounding service zones.
[0040] FIG. 1 shows a travel route 108 taken by a transport 104 picking up a first customer 110 at a first location 111 and delivering the first customer 110 to the hub 102 . It is possible that the transport 104 can pick up a second customer 112 at a second location 114 when transporting the first customer 110 to the node 102 as long as the predetermined transit time period can still be met.
[0041] The same predetermined transit time requirement can also apply to transporting a customer 120 from the hub 102 to a second location 122 within the service zone 100 .
[0042] FIG. 2 depicts two service zones 100 , 130 , one surrounding the hub 102 , which will be described, for example, as utilizing transports 104 to pick-up a customer 109 and transport the customer 109 to the hub 102 . From the hub 102 , the customer 109 travels along the urban transit system 134 to a hub 132 in a second service zone 130 . At the second in hub 132 of the second service zone 130 , a separate set of transports 136 transport the customer to drop off location 138 within the second service zone 130 .
[0043] FIG. 3 depicts multiple service zones, each with a small amount of overlap with adjacent service areas arranged in a city or city area along urban transit lines.
[0044] For operation of the roaming transport distribution management system, each customer or potential customer 400 , as shown in FIG. 4 , would utilize a communication device 402 . The communication device 402 may be any communication device, such as a cellular telephone, smartphone, laptop computer, tablet computer, desk-top computer etc., as long as the communication device 402 is capable of generating a pick-up request via wireless communication network 404 , such as cellular network, to a system manager 406 , also referred to as a server 406 , as well as sending GPS location signals generated by use of a device capable of communication with GPS satellite 408 to identify the pick-up location of the customer 400 .
[0045] Each transport 410 within the service zone 100 will also carry a communication device 412 , such as a computer, a portable computer, a cellular telephone, tablet computer, etc., with wireless network communication and GPS communication capabilities.
[0046] The server 406 , as described hereafter, may be a physical computing device with at least one processor, memory, database and wireless and GPS communication capabilities, which communicates with the customers 400 and the transports 410 via the wireless communication network 404 using GPS location data generated by the communication devices 402 and 412 carried by each customer 400 and transport 410 .
[0047] In general, one customer 400 will generate a pick-up request by using an application on his communication device 402 to transmit his GPS location and the pick-up request through the wireless network 404 to the server 406 . The pick-up request may identify the customer's name and include other customer information as well as special instructions, including time deadlines, number of passengers, luggage, etc.
[0048] In response to a pick-up request from a customer 400 , the server 406 , as described hereafter, will dynamically select one service transport 410 within the service zone 100 which is capable of traveling from the current location of the transport 410 to the location of the customer 400 , pick up the customer, and then transport the customer along the fastest route to the hub within the predetermined maximum transit time period. This direction of customer 400 travel from a pick-up destination to the node is referred to as an inbound transport.
[0049] For inbound requests, shown in FIG. 11 , the server 406 sorts the transports in the service zone to determine which transport is closest to the customer making the request in step 900 . If the the closest transport to the customer making the request is already at full occupant capacity, in step 902 , then the server 406 advances to check the next closest transport in the service zone to the customer making the request.
[0050] Alternately, if the selected transport in step 900 is determined in step 902 to not be at full occupant capacity, the server 406 queries if the transport is roaming in step 904 . Roaming is the availability of a transport, either stationarily parked or moving within its defined coverage area, described hereafter, and available for customer transport. A transport is removed from roaming when a transport is directed to pick up a customer or is inbound or outbound with customer(s) to and from the hub in the service zone.
[0051] If the transport is not roaming, the server 406 advances to step 906 to query if the selected transport 410 is inbound to the hub. If the selected transport is not inbound to the hub as determined in step 906 , the server 406 advances to the next closest transport.
[0052] Referring back to step 904 , if the server 406 determines that the selected transport is roaming, the server 406 determines if the wait time between the time that the customer made the request and the time that the selected transport 410 will arrive at the location of the customer is above a maximum wait time. If yes, the server 406 advances to select another transport. However, if the determined wait time is below the maximum wait time in step 908 , the server 406 assigns the selected transport to the customer request in step 910 .
[0053] Referring again to step 906 , if the server 406 determines that the transport is inbound to the hub, the server in step 912 queries where the selected transport will have to move in a direction away from the hub in order to pick up another customer making the current request. If the answer is yes from step 906 , the server 406 advances to select another transport.
[0054] However, if the determination in step 912 is negative, the server 406 in step 914 queries if the selected transport is heading in a direction toward the same hub as the hub in the current customer request. If not, the server 406 selects another transport to honor the customer request. However, if the determination in step 914 is yes, the server determines in step 916 if the trip time for the selected transport of the first customer picked up by the transport will exceed the predetermined transit time, such as 15 minutes, for example, in step 916 if the transport picks up the second customer making the current request. If the transit time for the first customer is less than the predetermined transit time, such as 15 minutes, from step 916 , the server assigns the selected transport to honor the customer request in step 918 . However, if the outcome of the query in step 916 is yes, that is, the maximum transit time would be exceeded, the server 406 advances to select another transport to honor the current customer request.
[0055] Outbound transportation via transport from the hub is also possible after the customer arrives at the hub. For example, the customer communicates via the wireless network through his communication device 402 or other means of communication to the server 406 informing the server 406 of his expected arrival time at one particular hub, along with other customer identification, preferences, etc. The server 406 then communicates with the driver of a transport 410 to insure that a transport 410 is at the hub at the time the customer 400 arrives at the hub. The transport 410 then picks up the customer 400 and transports the customer 400 to his or her drop off designation within the service zone 100 . This will be referred to hereafter as an outbound transport.
[0056] As shown in FIGS. 12A and 12B , upon receiving an outbound request from a customer, the server 406 sorts the transports in the service zone to determine which transport is closest to the hub in step 940 . If the first selected transport is determined to be roaming in step 942 , the server 406 assigns the selected transport to honor the customer outbound request in step 944 .
[0057] However, if the selected transport 942 is not roaming, the server 406 queries if the transport is inbound to the hub with customers in step 946 . If answer is yes from step 946 , the server 406 in step 948 queries if the outbound capacity of the selected transport has been reached. If the answer to the query in step 948 is yes, the server 406 advances to select another transport to honor the outbound customer request.
[0058] However, if the outcome of the query in step 948 is negative, the server 406 determines if the outbound trip time of the selected transport is above the maximum wait time for the outbound customer request in step 950 . If the determination is yes, the server 406 advances to select another transport. However, if the inbound trip time is below the maximum wait time to honor the outbound customer request, the server 406 in step 952 determines if the outbound trip time to the customer's destination is greater than the maximum transit time in step 952 . If the determination is yes, the server 406 advances to select a different transport. However, if the outcome of the query in step 952 is negative, the server 406 queries in step 954 if the time between drop offs at the hub and the destination of the outbound customer request is too large. If the determination is yes, the server 406 advances to select a different transport. However, if the time between drop offs is not too large or is below a preset maximum time, the server 406 will assign a selected transport to honor the outbound customer request in step 956 .
[0059] Referring back to step 946 in FIG. 12A , if the server 406 determines that the transport is not inbound with customers, the server 406 next checks if the inbound transport is without customers or is waiting at the hub in step 958 . If this determination is negative, the server 406 checks for another transport.
[0060] However, if the outcome in step 958 is yes, the server 406 determines if the outbound capacity of the selected transport has been reached in step 960 . If yes, the server 406 searches for another transport. If not, the server 406 determines in step 962 if the outbound trip time for all passengers in the transport is greater than the maximum predetermined transit time in step 962 . If the outcome is yes, the server 406 searches for another transport.
[0061] However, if the determination in step 962 is negative, the server 406 in step 964 determines if the time between drop off locations of the multiple customers going to different destinations in the same transport is greater than a maximum allowed time. If yes, the server 406 searches for a different transport. However, if not, the server 406 assigns the transport in step 966 to the new request.
[0062] The server 406 communicates via the wireless communication network 404 with the communication device 412 in the transport 410 and provides the driver of the transport 410 with the customer location, customer information, and other pertinent data. The server 406 also transmits information pertaining to the most expeditious route from location of the transport 410 to the first location of the customer 400 and then from the first location to the hub.
[0063] Further, the server 406 dynamically repositions the transport 410 within the service zone to optimum positions, even when the transport 410 is not transporting a customer or traveling toward a customer pick-up location. This enables the transports 410 within a service zone 100 to be optimally distributed in a manner responsive to population density and service request density in order to enable the predetermined maximum transit period to be met for all customers within a service zone.
[0064] The server 406 can dynamically change the location of one or more of the transports 410 within the service zone 100 at different times of the day to meet varying service request densities, such as morning rush hour, evening rush hour, afternoon or evening sporting events, etc.
[0065] The roaming transport distribution management system, as shown in FIG. 5 , includes a system manager which may be incorporated into the server 406 shown in FIG. 4 . The system manager 406 includes a controller, such as a processor based computing device coupled to a database 504 .
[0066] It will be understood that the following description of the main functional blocks of the system manager or server 406 may be virtual elements, rather than physical computing devices.
[0067] The controller 502 is responsible for creating, deleting, and managing all of the different components of the system manager. The controller 502 creates hub monitors 506 , which monitor one or more hubs 510 within a particular area. For example, a single hub monitor 506 can monitor five hubs 510 .
[0068] The hub monitors 506 gather information necessary for the operation of the controller 502 . The hub monitors 506 carry out their own thread gathering asynchronously. The hub monitors 506 primarily keep track of the location of each hub 510 and the area of coverage of the assigned hub 510 .
[0069] A hub locator 508 accesses each of the hub monitors 506 to obtain information about the hubs 510 . When a customer request 512 is received by the system manager 406 , the controller 502 passes the request to the hub locator 508 which creates a thread and processes the hub information to determine which hub 510 should receive the request.
[0070] The hub locator 508 is coupled to a hub dispatcher 514 , which is responsible for sending the request to a hub, or the hub locator 508 has located hub manager 510 after it. A notification manager 516 is provided as part of the system manager 407 to enable communication between the various components of the system manager 407 . The notification manager 516 also enables threads associated with each customer request and customer transport to the hub to notify other threads when they have completed their tasks. Each thread registers itself with the notification manager 516 .
[0071] Each of the components of the system manager 407 registers itself with the notification manager 516 . The hubs 510 also register themselves with the controller 502 , which in turn passes on the hub information to the hub monitors 506 . If a hub monitor 506 is at full capacity with the predetermined number of hubs, the controller 502 will create a new hub monitor 506 . When the system manager 407 receives a request 512 , a hub locator 508 thread is created. The hub locator 508 looks at all of the hubs 510 controlled by hub monitors 506 to locate the closest hub 510 within a certain predetermined distance range from the customer location issuing the request 512 .
[0072] The hub managers 516 controlling each hub 510 include a roaming distribution transport algorithm for distributing transports within a service zone surrounding a hub 510 to enable each customer request 512 to be accepted and the customer delivered to the hub 510 within the predetermined maximum time period or window, such as 15 minutes for example. Even though the illustrated service zone covers concentric circles up to a four-mile radius, it will be understood that the service zone, depending upon geographic factors, population density and request density, may have a larger or smaller service area, such as from one mile up to greater than four miles.
[0073] Since maintaining all of the transports at the hub 510 would require the transports to travel a first distance out to the location of a customer making a request for transport and then retrace the same distance back to the hub, the transports would easily exceed the predetermined transit time period. As such, the transports need to be distributed throughout the service zone.
[0074] Prior transit applications provide an even distribution of the transports across the entire service zone. However, this does not take into account variations in population density, request density, geographic factor, etc.
[0075] The roaming distribution transport algorithm executed by each hub manager 510 automatically insures that the transports are distributed in a certain manner across the entire service zone so that a customer request originating from any location within the service zone can be honored within the predetermined transit time period met.
[0076] FIGS. 6-9 depict the service zone 100 . Although the service zone 100 is illustrated as having a circular shape, it may have other shapes, such as rectangular, square, polygonal or an irregular peripheral boundary depending upon population density, transit request density, geographic factors, etc. The service zone 100 can have any maximum radius. The four-mile radius shown in FIGS. 1-3 may be applied to the service zone 100 . Alternately, the service zone 100 can represent the one-mile sub-zone of the service zone 100 shown in FIGS. 1-3 . The service zone could also apply to the entire area covered by the two-mile radius, the three-mile radius, or the four-mile radius.
[0077] As shown in FIG. 6 , each transport is represented by a geometric exclusive coverage area 600 , with the circular shaped coverage area shown by way of example only. Each transport is located at approximately the center of its coverage area 600 and can be stationary, or moving within a small area generally centered within the coverage area 600 .
[0078] The distribution algorithm eliminates overlaps between the coverage areas 600 of all of the transports within the service zone 100 .
[0079] In one configuration, all of the transports have the same size exclusive coverage areas 600 as shown in FIG. 6 . The distribution algorithm, while preventing overlap between any of the edges of coverage areas 600 of the transports, is capable of moving each coverage areas 600 including coverage areas 600 A- 600 F both radially inward and outward, or circumferentially, or in any direction (straight, arcuate, zigzag, etc.), as shown by the arrows in FIG. 6 , to achieve a transport distribution which places one transport within range of any customer issuing a request within the service zone 100 to meet the predetermined maximum transit time for moving a particular transport from the present location of the transport to the location of the customer issuing the request, picking up the customer, and then transporting the customer to the hub 602 .
[0080] In FIG. 7 , the transport in coverage area 600 A has moved to pick up a customer and can be transiting toward the hub 602 . As soon as the transport is assigned a customer request and begins moving toward the location of a customer, the hub manager 510 removes the transport 600 A from roaming, as shown by the gap in FIG. 7 where coverage area 600 A of the assigned transport has been removed. However, its coverage area 600 A continues to impact the coverage areas of the remaining roaming transports.
[0081] The roaming distribution transport algorithm then rebalances the location of at least one or more of the remaining transports and their associated coverage areas 600 by slightly moving one or more of the coverage area 600 in circumferential, straight, curved, or radial directions to the distribution shown by example in FIG. 8 . The hub manager 510 for the service zone 100 moves, for example, coverage area 600 E radially inward to fill the gap left by the removal of the transport in coverage area 600 A. The arrows in the adjacent coverage areas shows some of the directions that the hub manager 510 can move each of the coverage areas.
[0082] Any of the adjacent coverage areas 600 B, 600 C, 600 E and 600 F and their associated transports, can also be moved to a new rebalanced distribution.
[0083] As shown by example in FIG. 9A , three gaps 600 H, 600 I, and 600 J exist in the service zone coverage areas due to three transports being assigned to customer pick up. It should be noted that these gaps are a momentary occurrence and would normally be filled with coverage areas of adjacent located transports, such as coverage areas 600 L, 600 M, and 600 N in the manner described above.
[0084] FIG. 9B depicts the operation of the hub manager 510 or server 406 in reinserting a transport back into service zone 100 after the transport has dropped off a customer at the hub 602 . In this example, the hub manager 510 reinserts a transport shown by its coverage area 600 K in the innermost ring of coverage areas surrounding the hub 602 . The hub manager 510 rebalances the location of selected ones or all of the coverage areas 600 A- 600 M in the service area 100 , as shown in FIG. 9B , to accommodate the reinserted transport and its coverage area 600 K.
[0085] The hub manager 510 operates in a similar manner when a transport has dropped off a customer at the customer destination at any location within the service zone 100 , after transit from the hub 602 or from another location within the service zone 100 . The hub manager 510 can reinsert the transport, once the customer has been dropped off, at its then current location or direct a transport to a different location to fill a gap in the coverage areas within service zone 100 .
[0086] This minimizes to a certain extent some of the larger gaps at the perimeter of the service zone 100 , but large gap areas or open spaces at the perimeter of the service zone 100 still exist; but should be able to be covered by the closet transport to meet the maximum predetermined transit time.
[0087] Referring back to FIG. 9A , three gaps denoted by the removal of transport coverage areas 600 H, 600 I, and 600 J are shown in service area 100 . The hub manager 510 and the server 406 can fill these gaps by also enlarging coverage areas associated with selected transports in addition to redistributing the coverage areas within the service zone 100 . The enlarged coverage areas 600 J, 600 L, and 600 N still enable customer request within the service zone 100 to be met within the predetermined pickup and/or transit time.
[0088] The distribution algorithm also is capable of taking into account population density variations within the service zone 100 , historic request density variations within the service zone 100 , as well as the current distribution of transports within the service zone 100 . The distribution algorithm, as shown in FIG. 9D , is capable of initially providing or varying the size, in the case of the coverage areas 600 and/or the radius or diameter of each coverage area 600 , based on the population or historic request density variations within the service zone 100 .
[0089] FIG. 9D shows multiple different diameter sizes of the coverage areas 600 , with the size corresponding to the area of coverage for a particular transport located within each coverage area 600 . Larger diameter circles, for example, indicate a larger coverage area for a particular transport. The smallest diameter circles indicate a small exclusive coverage area for a particular transport.
[0090] As shown in the upper right quadrant of the service zone 100 in FIG. 9 , there is a larger density 603 of small diameter coverage areas 600 . This indicates the high population density or a high historic request density within this area of the service zone 100 . Conversely, in the left quadrant area 605 of the service zone 100 , predominately larger sized coverage areas 600 are shown. This indicates a larger exclusive coverage area for each transport and a corresponding smaller number of transports in this area of service zone 100 .
[0091] Since higher request density sub-zones of the service zone will have more customers and therefore more transports removed from the number of available transports, additional transports are provided in such areas with smaller coverage areas to accommodate all customers and still meet the predetermined transit time period.
[0092] With the variable size indicator capability within the distribution algorithm, when a particular transport is removed from roaming distribution since it is transporting a customer to the hub 602 , can redistribute and rebalance the remaining available transports by either resizing the diameter of the coverage area of one or more transports or by adjusting the position of one or more of the transport coverage areas, or both changing the size of certain coverage areas and rebalancing the position of some or all of the transports and their coverage areas.
[0093] In any of the rebalancing or resizing computations performed by the distribution algorithm, the hub manager 510 will issue position commands to the effected transports via the communication network which direct the transports to change the center of their location, either the position at which they are parked or the center of the position about which they are roaming to a new position. The algorithm can incorporate a distance tolerance so that the transports are not commanded to move only short distances, but commands will be issued only when a more significant difference, such as 400 meters for example, is necessary.
[0094] The hub manager 510 receives GPS signals from the transports indicating the current position of the transports and is therefore capable of both monitoring the location of all of the transports within the respective service zone as well as issuing commands for one or more of the transports to move to different geographic locations.
[0095] FIG. 10 depicts a modification to the coverage area 100 described above. In FIG. 10 , the same central service area 100 around central node 102 still exists. However, additional coverage areas, with three coverage areas 800 , 802 and 804 being shown by example, are each formed about separate nodes or hubs such as stations on mass transport lines. It will be understood that separate coverage areas, similar to coverage areas 800 , 802 and 804 , may be provided around each node or station in the transport area or only about certain hubs or stations. Coverage areas 800 , 802 and 804 may be the same size as the coverage area 100 or maybe smaller or larger in coverage areas. Further, the coverage areas 800 , 802 and 804 can be separate from or, overlap each other and, in conjunction with the central coverage area 100 can form a single enlarged coverage area. Transports, as distributed and described above, in the central coverage area 100 may also serve the additional coverage areas 800 , 802 and 804 . The distribution of the transports may be treated as a single large transport coverage area, including coverage areas 100 , 800 , 802 and 804 , with transport roaming within the enlarged coverage area formed by the coverage areas 100 , 800 , 802 and 804 and changing which hub each transport goes to depending upon what is most efficient in terms of customer requests, transport location, customer destinations, customer pick up locations, time of day, etc.
[0096] The transports may be assigned and roam in the coverage area 100 , including any of the overlapped areas of the coverage area 100 and the coverage areas 800 , 802 , and 804 , where the transports may be dedicated to a specific coverage area 800 , 802 and 804 for a primary pick-up and delivery of customers from a pick-up point to an end destination, such as any of the coverage areas 800 , 802 and 804 , or from the hubs in the coverage areas 800 , 802 and 804 to an end destination within or without of coverage areas 800 , 802 and 804 to an end destination within or without the coverage areas 800 , 802 and 804 .
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A roaming transport distribution management apparatus and method are provided. A controller selects transports within a defined service zone in response to customer transit requests from customer locations or a central hub which are capable of meeting maximum transit time to the end destination in either an inbound or outbound direction from the hub. A hub manager varies the position and/or the size of an exclusive coverage area of each transport within the overall service zone to insure a dense accumulation of transports over the entire service zone and alters the position of other transports in response to the movement of a transport inbound or outbound from the hub with a passenger. The hub manager can vary the size of the exclusive coverage area of each transport to account for population and request call densities and the number of available transports.
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CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority of German application No. 10 2010 039 312.6 filed Aug. 13, 2010, which is incorporated by reference herein in its entirety.
FIELD OF THE INVENTION
[0002] The invention relates to a method for simulating a blood flow in a vascular segment of a patient during angiography examinations.
BACKGROUND OF THE INVENTION
[0003] “Computational Fluid Dynamics”, also known as CFD for short, is a method for simulating the blood flow in a vascular section or vascular segment of a blood vessel which contains a pathological, i.e. a morbid change. Such a pathological change in the vascular section exists for example in the form of an aneurysm, i.e. a morbid, locally delimited, frequently bag-like enlargement. An aneurysm can occur in particular in a blood vessel in the region of the brain or of the heart; however, the occurrence of an aneurysm is generally not restricted to a specific region of the body. The clinical significance of an aneurysm, which for example is localized in the brain, arises in particular from the risk of a rupture, i.e. the formation of a tear or burst, which for example can result in hemorrhages and thromboses. In modern medicine, the dynamics of the blood flow in an aneurysm are frequently considered to be a major factor in the pathogenesis of the aneurysm, i.e. in its formation and development.
[0004] This simulation of the blood flow by CFD methods imparts a three-dimensional distribution of the flow parameters, such as for example WSS (Wall Shear Stress), along the surface of the vascular lumen.
[0005] DE 10 2008 014 792 B3 describes such a method for simulating a blood flow in a vascular section, wherein a captured image of a vascular region including the vascular section is obtained, a 3D vascular section model is determined from the captured image, a number of blood flow parameters are read in, the blood flow is simulated in the vascular section model with the inclusion of the or every blood flow parameter and a number of hemodynamic parameters are output. It is here provided that the captured image is obtained with an implant used in the vascular section such that image data of the implant is included, and that the 3D vascular section model is determined having regard to the image data of the implant used. Furthermore, a corresponding apparatus for simulating a blood flow in a vascular section is specified.
[0006] As is known from the article “Image-Based Computational Simulation of Flow Dynamics in a Giant Intracranial Aneurysm” by D. A. Steinmann et al. [1], a number of what are known as hemodynamic parameters are related to a growth and a burst of the aneurysm. A hemodynamic parameter is understood in particular as a parameter which relates to the hemodynamics, i.e. fluid mechanics, of the blood. In the cited article a pressure, a stress and shear stress affecting the vascular wall, as well as a flow rate, are mentioned among other things as hemodynamic parameters. In order to extrapolate such hemodynamic parameters, the blood flow in a vascular section which for example includes the aneurysm, is for example simulated.
[0007] In this article by D. A. Steinmann et al. [1] a 3D vascular section model is determined to this end from a 3D captured image which was obtained by means of rotational angiography. The blood flow in the 3D vascular section model is simulated using the CFD method. The simulation is performed here on the assumption of rigid vascular walls and a constant blood viscosity. CFD is a method of numeric flow simulation. The model equations used in numeric fluid mechanics are mostly based on a Navier-Stokes equation, on an Euler equation or on a potential equation.
[0008] This method of blood flow simulation is currently being employed in a number of experimental studies. A major restriction is that in this specific application on humans not all basic conditions necessary for the simulation are sufficiently precisely known on an individual patient basis. Hence it is difficult to validate the method and in the past this has not been done.
[0009] This means that the resulting flow results for the individual patient may be incorrect. Important basic conditions here include the geometry of the vascular section with aneurysm, the inflow and outflow values of the blood which change over time (speed, volume, etc.), the characteristics of the blood and the local elastic characteristics of the vascular wall.
[0010] To perform such rotational angiography to generate 3D captured images in order to obtain a 3D vascular section model, use is made of X-ray systems, the typical important features of which can for example be at least one C-arm, which can be robot-controlled and to which an X-ray tube and a radiographic image detector are attached, a patient support table, a high-voltage generator for generating the tube voltage, a system control unit and an imaging system including at least one monitor.
[0011] Such a typical X-ray system with a robot-mounted C-arm shown as an example in FIG. 1 for example has a C-arm 2 rotatably mounted on a stand in the four of a six-axis industrial or buckling arm robot 1 , with an X-ray radiation source, for example a radiographic tube unit 3 with X-ray tube and collimator, and a radiographic image detector 4 as an image capturing unit being attached to the ends of said C-arm 2 .
[0012] In general CTA and MRA are also suitable for generating the 3D models. The advantage with C-arm systems is that if necessary the 2D recordings are intrinsically registered. Otherwise this has to be done for all modalities.
[0013] Using for example the buckling aim robot 1 known from U.S. Pat. No. 7,500,784 B2 which preferably has six rotary axes and thus six degrees of freedom, the C-arm 2 can be spatially readjusted at will, for example by being rotated about a center of rotation between the radiographic tube unit 3 and the radiographic image detector 4 . The inventive X-ray system 1 to 4 can in particular be rotated about centers of rotation and rotary axes in the C-arm plane of the radiographic image detector 4 , preferably about the center point of the radiographic image detector 4 and about rotary axes intersecting the center point of the radiographic image detector 4 .
[0014] The known buckling arm robot 1 has a base frame which for example is permanently mounted on a floor. Attached to this is a carrousel which can rotate about a first rotary axis. Fixed to the carrousel is a robot swing arm which can swivel about a second rotary axis, to which is attached a robot arm which can rotate about a third rotary axis. Fixed to the end of the robot arm is a robot hand which can rotate about a fourth rotary axis. The robot hand has a fixing element for the C-arm 2 which can swivel about a fifth rotary axis and can rotate about a sixth axis of rotation running perpendicular thereto.
[0015] The implementation of the radiographic diagnostic device is not reliant on the industrial robot. Standard C-arm devices can also be used.
[0016] The radiographic image detector 4 can be a rectangular or quadratic, flat semiconductor detector which is preferably made of amorphous silicon (a-Si). However, integrating and possibly metering CMOS detectors can also be used.
[0017] In the beam path of the radiographic tube unit 3 a patient 6 to be examined is placed on a patient support table 5 as an examination object for recording a heart for example. Connected to the radiographic diagnostic device is a system control unit 7 with an image system 8 which receives and processes the image signals from the radiographic image detector 4 (operating elements are for example not shown). The X-ray images can then be viewed on displays of a bank of monitors 9 .
[0018] In the methods currently used for blood flow simulation not all basic conditions necessary for the simulation are sufficiently precisely known on an individual patient basis in this specific application on humans. Hence it is difficult to validate the method. In the references cited below, different approaches are mentioned which enable CFD simulations to be validated.
[0019] In “Blood flow in cerebral aneurysm: Comparison of phase contrast magnetic resonance and computational fluid dynamics—preliminary results” by Karmonik et al. [2] the result of a CFD simulation is compared to MR. The MR measurement itself is however imprecise because of the limited resolution and requires a considerable investment in time. Moreover this examination is virtually never performed on patients.
[0020] In “Methodologies to assess blood flow in cerebral aneurysm: Current state of research and perspectives” by Augsburger et al. [3] a procedure using in-vitro transparent vascular models and “Particle Image Velocimetry” (PIV) is described which permits CDF data to be compared to measured data.
[0021] However, neither method is suitable for validating the CFD measurement for the individual patient.
[0022] In “Quantitative evaluation of virtual angiography for interventional X-ray acquisitions” by Sun et al. [4] a method is described which is suitable for verifying CFD simulations for the individual patient in a particular way. To this end the CFD simulation is used to create a virtual angiography which can be compared to a genuine angiography recording of the patient. The result is a qualitative comparison in 2D. A description is additionally given of how to generate a center line and create a flow map along this center line in both angiography recordings. These two lines can be used to perform a quantitative comparison in ID (along the line), which can be specified in the form of a relative mean quadratic error.
SUMMARY OF THE INVENTION
[0023] The object of the invention is to design a method for simulating a blood flow in a vascular segment of a patient during angiography examinations by a radiographic diagnostic device having a radiographic tube unit and a radiographic image detector, a patient support table and a system control unit, wherein a captured image of an examination region including the vascular segment is obtained, a 3D vascular model is determined from the captured image, a number of blood flow parameters are read in, and with the inclusion of these blood flow parameters the blood flow in the 3D vascular model is. The method enables the CFD simulation results to be validated for the individual patient, or any deviations to be quantitatively determined and used iteratively to improve the CFD simulation.
[0024] The object is inventively achieved for a method by the features specified in the independent claim. Advantageous embodiments are specified in the dependent claims.
[0025] The object is inventively achieved by the following steps:
a) Recording a 3D image dataset of an examination region including the vascular segment ( 20 ) for generating a 3D reconstruction image of the examination region, b) Generating a 3D vascular model from the 3D image dataset, c) Capturing a contrast agent propagation in the examination region by means of dynamic 2D angiography methods for generating real 2D angiography recordings, d) Inputting at least one blood flow parameter, e) Starting a CFD simulation of the blood flow in the 3D vascular model with the inclusion of the at least one blood flow parameter, f) Generating virtual 2D angiography recordings from the results of the CFD simulation, g) Determining a degree of correspondence between the real and the virtual 2D angiography recordings from identical angulation and adjusted recording geometry of the individual patient, h) Comparing the degree of correspondence with predefinable tolerance values, i) Iteratively optimizing the CFD simulation while changing the at least one blood flow parameter as a function of the comparison according to step h) and j) Outputting the degree of correspondence (B i, j ) for the evaluation of the correspondence between the virtual and the real angiography.
[0036] As a result information about the local blood flow, in and out of the vascular segment under consideration, can hereby be iteratively adjusted to the real 2D angiography recordings taken.
[0037] In fact a new dimension is introduced with the degree of correspondence. Even if other parameters are normally taken from the 2D angiography, these can currently only influence the CFD simulation if they are also used as simulation-relevant parameters.
[0038] The definition of the degree of correspondence and its iterative optimization is not reliant on extracting specific flow information from 2D angiography, since these parameters are very often defective. For some time attempts have been made to measure blood speeds in medical angiographies and to date no method is in use. Thanks to the comparison and the degree of correspondence any target parameters (e.g. contrast agent behavior at the highest point of the aneurysm), however abstract they are for the basic conditions for CFD simulation, can be employed for optimization. The aim is to optimize not the flow parameters (basic conditions or manipulated variables) used for the simulation, but the results of the CFD simulation. These must ultimately correspond to the real world. The person skilled in the art will ensure that no irrelevant conditions are obtained.
[0039] Advantageously the recording of a 3D image dataset of an examination region including the vascular segment can be obtained according to step a) by means of a radiographic diagnostic device with a radiographic tube unit and a radiographic image detector, a patient support table and a system control unit.
[0040] According to the invention a segmentation of the relevant vascular segment can be performed.
[0041] It has proved advantageous if the parameters for correcting each segment are selected individually if the vascular segment has several efferent vessels in which the correspondence in both outflowing vascular segments is different.
[0042] According to the invention the time intensity curves can be obtained for CFD simulation according to step e) from two scenes for each pixel or for a combination of several pixels, with at least one characteristic variable being extracted from said curves.
[0043] According to the invention, time values, intensity values and/or intensity values at defined times can be extracted as characteristic variables.
[0044] Advantageously the degree of correspondence according to step g) can be formed as follows:
[0000]
B
i, j
=T
i, j
−T*
i, j
[0000] with the degree of correspondence and the extracted variables for each pixel i,j from both angiographies.
[0045] According to the invention the degree of correspondence according to step g) can be a normalized degree of correspondence.
[0046] It has proved advantageous if the degree of correspondence according to step g) is determined for the bolus arrival times.
[0047] According to the invention the degree of correspondence according to step j) can be represented as an image and/or color-coded as a two-dimensional field.
[0048] Advantageously the 3D vascular model can be a 3D vascular section model or a 3D vascular surface model.
[0049] According to the invention, at least one of the following basic conditions can be input as blood flow parameters according to step d):
geometry of the vascular section with aneurysm, inflow and outflow values of the blood, changing over time, pressure at the inflow and outflow region, blood characteristics and local elastic characteristics of the vascular wall.
[0055] It has proved to be advantageous if the pressure difference between inflow region and outflow regions, the flow rate and/or the blood volume are selected as a basic condition as inflow and outflow values of the blood, changing over time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0056] The invention is explained in greater detail below on the basis of the exemplary embodiments shown in the drawing:
[0057] FIG. 1 shows a known X-ray system with an industrial robot as a support apparatus for a C-arm,
[0058] FIG. 2 shows time intensity curves (TIC) with characteristic variables drawn in to explain the invention,
[0059] FIG. 3 shows an example of a vascular branching with aneurysm for defining ROIs and the associated basic conditions of flow Q and pressure P,
[0060] FIG. 4 shows a flowchart of an inventive method sequence and
[0061] FIG. 5 shows an inventive workflow.
DETAILED DESCRIPTION OF THE INVENTION
[0062] In the inventive method, apparatus and workflow a degree of correspondence between a virtual angiography from a CFD simulation and a real angiography scene is determined and this degree of correspondence is used to purposefully and iteratively optimize the CFD simulation.
[0063] This degree of correspondence is based on the comparison between a virtual angiography and a real angiography from identical angulation and adjusted recording geometry of the individual patient. The inventive determination of the degree of correspondence in 2-D is an alternative approach to Sun et al. [4].
[0064] Output data for this degree of correspondence is dynamic angiography scenes, which show the diffusion or passage of the contrast agent through the corresponding vascular system. The virtual dynamic angiography S* (the values indicated by * always relate in the following to the data derived from the virtual angiography) is obtained by means of CFD simulation. The time intensity curves TIC i, j and TIC* i, j are now obtained from these two scenes S and S* for each pixel (or combination of several pixels).
[0065] In the next step one or also more characteristic variables can be extracted from these time intensity curves, as described in “Parametric color coding of digital subtraction angiography” by Strother et al. [5]. These can be time values and/or intensity values or intensity values at defined times.
[0066] FIG. 2 shows by way of example a time intensity curve (TIC) with drawn-in characteristic variables, in which the blood flow is plotted as intensity I over time t. After a noise-like behavior of the bolus curve 10 the intensity I climbs to the intensity maximum 11 (I max ), in order then to drop back to a noise level. The bolus curve 10 is furthermore characterized by its half-width 12 (FWHM—Full Width at Half Maximum), which lies between the mean rise and the mean drop of the bolus curve.
[0067] The arrival time 13 (T rise ) is the time that elapses until the occurrence of the contrast agent bolus at the point under examination and thus until the rise in the bolus curve 10 . The mean rise time 14 (T rise, FWHM ) is the time that elapses until the occurrence of the half-width 12 of the bolus curve 10 , i.e. until the bolus curve 10 has reached half of the intensity maximum 11 (I max ). The time until the intensity maximum 11 (I max ) is called the maximum time 15 (T max ). The rise time 16 or wash-in time (T wash in ) characterizes the steep rise in the bolus curve 10 . The drop in the bolus curve 10 is characterized by the drop time 17 or wash-out time (t wash out ). The duration of the occurrence of the contrast agent bolus is characterized by the bolus or maximum time 18 (t Peak ).
[0068] In the following let T i, j or T* i, j be the extracted variable for each pixel i,j from both angiographies.
[0069] This produces a degree of correspondence B i,j of both angiographies from a mathematical link between both values T i, j or T* i, j , such as a simple subtraction for example.
[0000]
B
i, j
=T
i, j
−T*
i, j
[0070] This degree of correspondence is thus a two-dimensional field, which can be represented for example as an image (e.g. color-coded) and permits an evaluation of the correspondence between the virtual and the real angiography.
[0071] Theoretically this degree of correspondence can be determined as in Sun et al. [4] as a mean quadratic error for the entire curves TIC i,j and TIC* i,j . However, this means it is then subsequently not possible to say anything about the nature of the deviation and thus it cannot be used for purposeful control of the CFD optimization.
[0072] Until now, however, the two angiography scenes have not been synchronized. In this application there are various excellent vascular regions in the angiography images, among which are the vascular regions into which the blood or the contrast agent flows.
[0073] In an improved embodiment regions of interest (ROI) in these vascular regions can be defined in both images. In this case one or more ROI, or corresponding ROI* in the virtual image can be selected such that they cover the vascular inflow regions. In a next step the mean value of the characteristic variable T i,j , or T* i,j under consideration can be determined: MWT i,j , or MWT* i,j . From a comparison of these mean values a normalization is calculated in the following. This can be a difference (in the case of temporal values) or a factor e.g. in the case of intensity values, as well as other algorithms.
[0074] Thus the normalized degree of correspondence B i,j of both angiography recordings can be balanced:
[0000] B′ i, j =T i, j −T* i, j ( MWT i, j −MWT* i, j )
[0075] It is especially advantageous if the contrast inflow curve from the real angiography scene is used for the (initial) CFD simulation.
[0076] If the simulation of the virtual angiography is performed such that the virtual inflow of the contrast agent matches reality, a normalization can be dispensed with However, it can also happen that both curves are delayed in respect of one another at the time of inflow or have different grayscale values. In this case, depending on the question, normalization will bring an improvement.
[0077] Essential for the invention are the definition of a degree of correspondence and the use thereof to assess and optimize the CFD simulation individual to the patient which until now has not been possible in-vivo. In particular the missing information on the local flow, into and out of the vascular segment under consideration, can herewith be adjusted iteratively to the real recorded 2D angiography recordings. This results in an improvement in the CFD results.
[0078] This is based on the idea of comparing a virtual angiography obtained from the CFD simulation with the real angiography, determining a degree of correspondence, or if there is a difference optimizing the CFD so that the correspondence becomes better.
[0079] In the case of a patient a 3D subtraction angiography with a C-arm system of the cerebral vessels and one (or more) 2D subtraction angiography scenes are recorded.
[0080] In a first step a 3D surface model is generated in the computer following a segmentation of the relevant vascular section around an aneurysm, which is then used as geometry for the CFD simulation. Moreover inflow and outflow regions are established.
[0081] FIG. 3 shows a vascular segment 20 with an afferent vessel 21 as an example for the definition of the region of interest ROI and the associated basic conditions flow Q and pressure P, which vessel branches into a first efferent vessel 22 and a second efferent vessel 23 . The vascular segment 20 furthermore has an aneurysm 24 . The inlet to the afferent vessel 21 is formed by an inflow region 25 . The outlet of the first efferent vessel 22 is formed by a first outflow region 26 and the outlet of the second efferent vessel 23 by a second outflow region 27 . A flow Q in (t) and a pressure P in (t) prevail in the region of interest ROI in of the inflow region 25 . In the region of interest ROI out1 of the first outflow region 26 a flow Q out1 (t) and a pressure P out1 (t) are measured and in the region of interest ROI out2 of the second outflow region 27 a flow Q out2 (t) and a pressure P out 2 (t) are measured.
[0082] The selected volume is adjusted here to the 2D angiography, i.e. an angulation and projection geometry corresponding to the 2D angiography are determined in the 3D angiography. If both recordings originate from an examination which involves no movement of the patient this is simple to calculate, but otherwise a registration must be performed. Thus the inflow region 25 and the outflow regions 26 and 27 are now also established in the 2D angiography.
[0083] In the following CFD simulation the propagation of an injected contrast agent is simulated, among other things. The temporal dynamics of the contrast agent inflow can be adjusted to the averaged time intensity curve from the 2D angiography. After the simulation a virtual 2D angiography is calculated by means of known angulation and projection geometry using forward projection (DRR), as is described for example in DE 10 2007 039 034 A1.
[0084] In a next step the normalized degree of correspondence B′ i,j e.g. for the bolus arrival times of both angiographies (real and virtual) is calculated.
[0085] If for example the typical vascular segment 20 with the afferent vessel 21 , the aneurysm 24 and the two efferent vessels 22 and 23 is considered, a further evaluation for control of an iterative CFD simulation can now take place. To this end the normalized degree of correspondence averaged in the ROI of the outflow regions 26 and 27 of the two efferent vessels 22 and 23 is considered. If it lies within a predefined tolerance, the result of the simulation is satisfactory in respect of these parameters, but otherwise this can be interpreted as a too fast or too slow flow in the entire vascular segment 20 . Physically this means that the basic condition of pressure difference between inflow region 25 and outflow regions 26 and 27 was selected suboptimally. This can happen, since the vascular resistance distally to the vascular arborization section under consideration is generally not known.
[0086] The tolerances can for example be predefined by a user. It is thereby determined how closely both angiographies, the virtual and the real angiography, must correspond before the user is satisfied.
[0087] If the normalized degree of correspondence is positive, the calculated flow is too low and in the subsequent CFD simulation the pressure difference or the pressure conditions must be increased at the outflow regions 26 and 27 (or variables corresponding thereto such as flow rate at the inflow region 25 ). In the case of a negative value the pressure difference can be reduced correspondingly.
[0088] If the correspondence in both outflowing vascular segments ROI out1 and ROI out 2 is different, this can be corrected individually for each segment by the individual selection of the parameters.
[0089] Another example of this is concerned with the vascular walls. In CFD simulations the vascular walls are increasingly treated elastically. A corresponding analysis can orient the regions of interest along the vascular walls. These are segmented to this end. The degree of correspondence is now determined locally for all pixels along the vascular wall and if values are too large the elasticity for the subsequent CFD simulation is adjusted. It is especially advantageous here if real angiographies from several angulations are present.
[0090] The inventive method is explained in greater detail on the basis of a flow chart shown in FIG. 4 . First comes an acquisition 30 of a 3D angiography image dataset for model generation 31 . In the further method step a recording 32 of a contrast agent propagation is generated by means of dynamic real 2D angiography. Then a CFD simulation 33 is performed, wherein it is possible to input 34 blood flow parameters as basic conditions. A virtual 2D angiography 35 from angulation identical to the real angiography 32 and adjusted recording geometry of the individual patient is calculated from this data. Then follows a determination 36 of a degree of correspondence based on a comparison between the virtual angiography 35 and the real angiography 32 and then a check 37 to see whether the degree of correspondence is sufficient, i.e. whether the degree of correspondence is within a predefined tolerance. If the degree of correspondence is insufficient, a change 38 in the basic conditions in terms of an optimization is performed. Then follows a new optimized CFD simulation 38 , by means of which again a determination 36 is performed, followed by a check 37 on the degree of correspondence. If in contrast the degree of correspondence is sufficient, the degree of correspondence is output 40 , for example as a color-coded image and the end of the examination is initiated.
[0091] A (percentage) figure, if a global correspondence is considered, as well as a local figure can be described, which then itself can be output as a color map (degree of correspondence). However, it is also possible to describe other values (for example the time difference for the maximum grayscale values).
[0092] FIG. 5 shows the method sequence or workflow of the inventive method with the following steps in greater detail:
S 1 ) 3D imaging for model generation, e.g. by means of 3D rotational angiography. S 2 ) Recording a contrast agent propagation by means of dynamic 2D angiography. S 3 ) Initial CFD simulation and generation of a virtual 2D angiography. S 4 ) Determining a degree of correspondence between real and virtual 2D angiography. S 5 ) If degree of correspondence is sufficient, continue with S 9 ). S 6 ) Changing one or more basic conditions of the CFD simulation according to the result of the degree of correspondence. S 7 ) Renewed, optimized CFD simulation with basic conditions changed in terms of an optimization. S 8 ) Back to S 4 ). S 9 ) Done—optimum CFD simulation was achieved.
[0102] The result is an iterative optimization of CFD simulation results based on the comparison between real and virtual 2-DSA recordings on the basis of a determination of a degree of correspondence between both recordings.
REFERENCES
[0000]
[1] Image-Based Computational Simulation of Flow Dynamics in a Giant Intracranial Aneurysm; David A. Steinman, Jaques S. Milner, Chris J. Norley, Stephen P. Lownie and David W. Holdsworth; American Journal of Neuroradiology (2003), Number 24, pages 559-566
[2] Blood flow in cerebral aneurysm: Comparison of phase contrast magnetic resonance and computational fluid dynamics—preliminary results; C. Karmonik, R. Klucznik, G. Benndorf; Fortschr Röntgenstr 2008; 180:1-7
[3] Methodologies to assess blood flow in cerebral aneurysm: Current state of research and perspectives; L. Augsburger, P. Reymond, E. Fonck, Z. Kulcsar, M. Farhat, M. Ohta, N. Stergiopulos, D. A. Rüfenacht; J. Neurorad.-168: 2009; pages 1-8
[4] Quantitative evaluation of virtual angiography for interventional X-ray acquisitions; Qi Sun, Alexandra Groth, Irina Waechter, Olivier Brina, Jürgen Weese, Til Aach; IEEE; 2009; pages 895-898
[5] Parametric color coding of digital subtraction angiography; C. M. Strother, F. Bender, Y. Deuerling-Zheng, K. Royalty, K. A. Pulfer, J. Baumgart, M. Zellerhoff, B. Aagaard-Kienitz, D. B. Niemann, M. L. Lindstrom; AJNR Am J Neuroradiol; 2010; www.ajnr.org; pages 1-7
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A method for simulating a blood flow in a vascular segment of a patient is proposed. A 3D image dataset of an examination region is recorded by a radiographic diagnostic device for generating a 3D vascular model. Contrast agent propagation in the examination region is captured by a dynamic 2D angiography method for generating a real 2D angiography recording. A CFD simulation of the blood flow is performed in the 3D vascular model based on a blood flow parameter for generating a virtual 2D angiography recording. A degree of correspondence between the real and the virtual 2D angiography recordings is determined from identical angulation and adjusted recording geometry of the patient and compared with predefinable tolerance values. The CFD simulation is iteratively optimized while changing the blood flow parameter as a function of the comparison. The degree of correspondence is outputted when the optimum CFD simulation is achieved.
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CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to provisional application 61/054,666, filed May 20, 2008.
FIELD OF THE INVENTION
[0002] This technique relates to adapters and equipment to provide varying access points for tubing and casing monitoring and casing annulus remediation systems.
BACKGROUND OF THE INVENTION
[0003] In wells drilled for petroleum production, a plurality of well casings of different sizes are suspended from a wellhead. A problem encountered in such wells is that of annular pressure control. In the annulus between different casing sizes, pressure may develop due to leaks between strings of casing. To control the pressure, a casing annulus remediation system is employed. The casing annulus remediation system comprises a hose that is inserted into an annulus between strings of casing. Often, the hose is inserted into the annulus through a lateral port that is often perpendicular to the casing, requiring the hose to maintain flexibility to accommodate the angle of entry. A nozzle is affixed to the lower end of the hose. The hose may be inserted several hundred feet into the well. Therefore, the hose must be pressurized and rigid to keep the hose from winding about the well. To keep the hose rigid, internal pressure is maintained in the hose. An angled access port would allow for the hose to be naturally more rigid. However, wells generally have standard lateral access ports.
[0004] A need exists for a technique that allows for more effective and efficient implementation of a casing annulus remediation system and subsequent insertion of a hose into an annulus. The following technique may solve one or more of these problems.
SUMMARY OF THE INVENTION
[0005] An apparatus and method for connecting a casing annulus remediation system to a well. The well has a wellhead with a longitudinal axis, a lateral port which is substantially perpendicular to the axis, and at least one string of casing supported in the wellhead and extending past the lateral port into the well, defining an annulus. The apparatus has a body with first and second ends. The first end of the body has a planar surface substantially parallel to the axis and is adapted to be in abutting contact with and connected to the wellhead, thereby covering the lateral port. The second end of the body has a planar surface positioned at an angle greater than 0 degrees and up to 90 degrees to the axis and is adapted to be connected to the casing annulus remediation system. A valve removal plug preparation is located in the planar surface of the second end of the body, and a valve removal plug is positioned within the valve removal plug preparation and is adapted to protect the valve removal plug preparation. A pilot hole is located in the planar surface of the second end of the body, perpendicular to the planar surface and is adapted to receive a drilling device.
[0006] The annulus of the well is sealed from the atmosphere by inserting a valve removal plug into the lateral port. The first end of the body is connected to the wellhead such that the planar surface of the first end substantially covers the lateral port and the valve removal plug. The shear capable valve of the casing annulus remediation system is connected to the planar surface on the second end of the body. An angled access port is created from the pilot hole, through the body, through the wellhead, and into the annulus. The remainder of the casing annulus remediation system is then connected to the shear capable valve.
[0007] In alternate embodiment, the body has a curved access port located in and extending through the body from the planar surface of the first end to the planar surface of the second end. The curved access port is aligned with the lateral port at the first end of the body.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a schematic view of a wellhead with a remediation system connected to the wellhead.
[0009] FIG. 2 is a schematic view of a wellhead manufactured with an angled entry port.
[0010] FIG. 3 is a schematic view of a wellhead with a remediation system adapter connected to the wellhead.
[0011] FIG. 4 is a schematic view of a wellhead with a standard remediation system adapter connected to the wellhead.
[0012] FIG. 5 is a schematic view of a wellhead with a custom vertical remediation system adapter connected to the wellhead.
[0013] FIG. 6 is a schematic view of a wellhead tree with a vertical remediation system connected to the tree.
[0014] FIG. 7 is a schematic view of a wellhead with a vertical remediation system connected to the wellhead.
[0015] FIG. 8 is a schematic view of a vertical remediation system with lift and hose reel cylinder extended.
[0016] FIG. 9 is a schematic view of a vertical remediation system with lift and hose reel cylinders compressed.
[0017] FIG. 10 is a schematic view of a vertical remediation system with a hose reel and a hose guide assembly connected to the remediation system.
DETAILED DESCRIPTION OF THE INVENTION
[0018] Referring to FIG. 1 , a wellhead 15 has annulus access ports 19 that permit access to an annulus section 17 of the well. In a typical wellhead 15 , annulus access ports 19 are located on the wellhead 15 , and run perpendicular to the well casing 16 . In this embodiment, a casing annulus remediation system (CARS) 21 has been connected to the wellhead 15 . In order to connect the CARS equipment 21 to the wellhead 15 , a shear capable valve 23 is connected to port 19 on wellhead 15 . A valve removal (VR) plug (not shown) is then removed from port 19 on the right side of the wellhead 15 through valve 23 . An annular blowout preventer (BOP) 25 is then connected to the shear capable valve 23 . A packoff 27 is located to the right of BOP 25 , and a hose driver 29 is located to the right of packoff 27 . Hose 31 is fed through the CARS equipment 21 by means of driver 29 . An articulated weight device 35 is connected to the end of hose 31 . The entry angle into annulus section 17 created by the orientation of access port 19 requires hose 31 to be extremely flexible. However, hose 31 must also be stiff enough to run downward through annular section 17 without winding or knotting occurring.
[0019] Referring to FIG. 2 , in order to simplify the implementation of a CARS, wellhead 41 is manufactured with an angled annulus access port 43 with the prospect of running the CARS program at some later point in its life. Access port 43 forms an angle greater than zero (0) degrees, and less than ninety (90) degrees with the well casing/structure. Port 43 is angled for easy entry into the annulus 51 . The interface surface 44 will be located ninety (90) degrees opposed to access port 43 . Interface surface 44 will allow for CARS equipment 21 ( FIG. 1 ) to be connected to wellhead 41 . Access port 43 has threads along its inner surface. A valve removal (VR) plug 45 with threads along its outer surface is threaded into access port 43 until the CARS equipment 21 ( FIG. 1 ) is connected to wellhead 41 . The CARS equipment 21 ( FIG. 1 ) is connected to wellhead 41 , beginning with shear capable valve 23 ( FIG. 1 ). VR plug 45 is then removed from port 43 and extracted through valve 23 . Valve 23 is then closed, and whatever exists on the outside of the valve 23 is vented off. The remainder of the CARS equipment 21 ( FIG. 1 ) is attached and the operating procedure for CARS is run. Access port 47 illustrates the standard port orientation. Angled access port 43 allows easier access to annular sections 51 with a hose or similar device. Additionally, the orientation of port 43 reduces the flexibility required of a hose or similar device that may be fed into annulus section 51 .
[0020] Referring to FIG. 3 , in order to create an angled access port 65 for a wellhead 61 that contains standard access ports 63 , CARS adapter 69 is employed. CARS adapter 69 is comprised of an interface surface 73 , which is ninety (90) degrees opposed to angled access port 65 . On the interface surface 73 , a VR plug preparation 75 is located within adapter 69 . VR plug preparation 75 has threads along its inner surface. A special VR plug 77 with a hole in it is initially threaded into VR plug preparation 75 and acts as a drill bushing and protects the threads of the VR plug preparation 75 during the installation of adapter 69 . Adapter 69 also contains a pilot hole 76 for drilling access port 65 .
[0021] In order to install adapter 69 , the annulus 64 of wellhead 61 is shut off to the atmosphere by the use of VR plugs 67 , which are placed in access ports 63 . The VR plug 67 on the right access port 63 of wellhead 61 will be a permanent attachment to the wellhead 61 once adapter 69 has been connected. Adapter 69 is bolted to the wellhead by a series of bolts 71 . A seal (not shown) seals between wellhead 61 and adapter 69 . After bolting up adapter 69 to the wellhead 61 , the CARS shear capable valve 23 ( FIG. 1 ) may be mounted to the interface surface 73 . A drilling device (not shown) with a drill is mounted to valve 23 in preparation for entry into the wellhead 61 . This drilling device (not shown) will have a seal such as is found on a VR extraction tool, as known in the art, to prevent anything from reaching the atmosphere as the drill makes entry into the annulus 64 through the valve 23 ( FIG. 1 ). The drilling device will drill through adapter 69 starting at pilot hole 76 . VR plug 77 allows the drill to pass through it and ensures that the threads in VR preparation 75 are protected from damage due to drilling. After annulus 64 is opened by drilling through wellhead 61 to form passage 65 , the drill (not shown) may be extracted, valve 23 ( FIG. 1 ) closed, the open side of valve 23 vented and the special drilling tool (not shown) removed.
[0022] The wellhead 61 is ready for the remainder of the CARS equipment 21 ( FIG. 1 ) to be mounted to the adapter 69 and used. After the use of the CARS equipment, the special VR plug 77 will be removed from the adapter and replaced with a standard VR plug (not shown), similar to VR plug 63 . This plug is solid and does not have a hole in it. The adapter 69 may be a permanent fixture and remain with wellhead 61 throughout its life. The original VR plug 67 and thread in port 63 on the right side of wellhead 61 will not be re-usable as it will be drilled through, and will remain with the wellhead 61 throughout its life. If the CARS system is later re-attached to adapter 69 , the standard VR plug (not shown), similar to VR plug 63 must be removed. In order to remove the standard VR plug, shear capable valve 23 ( FIG. 1 ) is connected to adapter 69 , and the standard VR plug is removed through it, before the remaining CARS equipment is connected.
[0023] Referring to FIG. 4 , CARS adapter 99 is employed in wellhead 91 where close proximity (such as a silo surrounding wellhead 91 ) prevents horizontal entry ( FIG. 1 ) through access port 93 . In order to enable entry into access port 93 on the right side of wellhead 91 , angled CARS adapter 99 is employed. CARS adapter 99 is comprised of an interface surface 103 , which can be positioned between zero (0) and ninety (90) degrees opposed to access port 93 . The adapter 99 contains a curved passageway 107 whose radius of curvature is dependent upon the angle 105 between access port 93 and interface surface 103 .
[0024] In order to connect CARS adapter 99 to wellhead 91 , a VR plug 97 is set in access port 93 of wellhead 91 . CARS adapter 99 is attached to wellhead 91 by a series of bolts 101 . After bolting up adapter 99 to the wellhead 91 , the CARS shear capable valve 23 ( FIG. 1 ) may be mounted to the interface surface 103 . Once the CARS valve 23 ( FIG. 1 ) is mounted to the top of adapter 103 , the VR plug 97 in access port 93 of wellhead 91 can be removed through valve 23 . The atmospheric side of valve 23 can then be vented, and the remainder of the CARS equipment 21 ( FIG. 1 ) is mounted and used. After the CARS service is performed, VR plug 97 can be re-inserted in access port 93 of wellhead 91 and adapter 99 can be removed to be used elsewhere. In FIG. 4 , no drilling of wellhead 91 occurs, unlike drilling passage 65 in FIG. 3 .
[0025] FIG. 5 illustrates an alternate embodiment of adapter 99 of FIG. 4 . CARS adapter 111 is employed in wellhead 91 where close proximity prevents full horizontal entry ( FIG. 1 ), but allows sufficient stroke length to horizontally remove VR plug 97 . In order to enable entry into access port 93 on the right side of wellhead 91 , angled CARS adapter 111 is employed. CARS adapter 111 is comprised of an interface surface 117 , which can be positioned from zero (0) and ninety (90) degrees opposed to access port 93 . The adapter 111 contains a curved passageway 119 whose radius of curvature is dependent upon the angle 121 between access port 93 and interface surface 117 . Adapter 111 also contains a VR plug preparation 114 , and VR plug removal tool interface 115 , both of which are positioned directly in line with port 93 .
[0026] In order to connect CARS adapter 111 to wellhead 91 , a VR plug 97 is set in access port 93 of wellhead 91 , CARS adapter 111 is attached to wellhead 91 by a series of bolts 113 . After bolting up adapter 111 to the wellhead 91 , the CARS shear capable valve 23 ( FIG. 1 ) may be mounted to the interface surface 117 . Once the CARS valve 23 ( FIG. 1 ) is mounted to the top of the adapter 111 , a plug retrieval tool (not shown) is used to remove plug 97 from wellhead 91 . This retrieval tool is inserted into tool interface 115 of adapter 111 and will remain in adapter 111 to continue sealing it off from the atmosphere until after the CARS operation is complete. The removal tool (not shown) removes VR plug 97 from access port 93 , and secures the VR plug 97 in VR plug preparation 114 until the CARS operation is complete. The atmospheric side of valve 23 can then be vented, and the remainder of the CARS equipment 21 ( FIG. 1 ) is mounted and used. After the CARS service is performed, VR plug 97 is re-inserted in access port 93 of wellhead 91 and adapter 111 can be removed to be used elsewhere.
[0027] FIG. 6 illustrates “top” or “vertical” entry of the CARS equipment 137 into a wellhead tree 131 without the need for rigging. A standard tree cap (not shown) is replaced with a CARS interface adapter 133 . The shear capable valve 139 will be mounted to the CARS interface adapter 133 , and the remaining CARS equipment 137 , including the annular BOP 141 , packoff 143 , and hose driver 145 are then assembled. FIG. 6 illustrates “vertical” entry of the CARS equipment 137 directly into the production tubing 135 of the wellhead tree 131 . The CARS equipment 137 , particularly hose 147 would be used inside of the production tubing 135 for implementation of various remediation systems.
[0028] FIG. 7 illustrates “top” or “vertical” entry of the CARS equipment 137 into a wellhead 155 without the need for rigging. A standard wellhead cap (not shown) is replaced with a CARS interface adapter 151 . The shear capable valve 139 will be mounted to the CARS interface adapter 151 , and the remaining CARS equipment 137 , including the annular BOP 141 , packoff 143 , and hose driver 145 are then assembled. FIG. 7 illustrates “vertical” entry of the CARS equipment 137 through access port 153 directly into the production casing 157 of wellhead 155 , with the production tubing pulled. The CARS equipment 137 , particularly hose 147 would be used inside of the production casing 157 for implementation of various remediation systems.
[0029] FIGS. 8 through 10 illustrate equipment to be implemented with “vertical” entry of CARS equipment. Referring to FIGS. 8 and 9 , CARS “vertical” entry equipment 161 is comprised of CARS adapter 159 , shear capable valve 163 , bottom frame plate 164 , BOP 165 , cylinders 170 , packoff 167 , top frame plate 169 , and driver 171 . Attached to driver 171 is spool positioning equipment 173 . Spool positioning equipment 173 is comprised of support arms 175 , 177 , pivot points 178 , 183 , 185 , cylinder (or other actuator) 181 , spool 179 , and hose 187 .
[0030] The CARS equipment 161 is fitted with cylinders 170 in order to raise and lower the packoff 167 and driver 171 . With the annular BOP assembly 165 in place, the hose driver 171 will have the packoff 167 attached to it but will not be fixed in its position to the annular BOP assembly 165 . The shear capable valve 163 will have a lower mounting plate 164 attached for two lift cylinders 170 on opposite sides of plate 164 . The hose driver assembly 171 with the packoff 167 attached will have an upper mounting plate 169 for cylinders 170 . As illustrated by FIG. 8 , the cylinders 170 will raise the hose driver assembly 171 and packoff 167 for attachment of an articulating weight device (not shown) to the hose 187 . The articulating weight device (not shown) can not be sent through the packoff 167 as it will damage the packoff 167 . As a result, the hose 187 is allowed to pass through the driver 171 and packoff 167 before the articulating weight device is attached to hose 187 . Once the articulated weight device is attached to hose 187 , the driver 171 and packoff 167 are lowered by cylinder 170 , and the BOP 165 is securely connected to the packoff 167 ( FIG. 9 ).
[0031] Referring to FIG. 8 , the spool positioning equipment 173 allows the hose spool 179 to be raised and lowered to a desired position. For example, positioning equipment 173 will allow spool 179 to be stored on a deck or level below that of the CARS equipment 161 . This lower position permits easier access and service to the hose reel assembly 179 . Once the CARS system is ready to be implemented, the spool 179 and hose 187 can be raised to a vertical position directly above driver 171 . Support arm 175 is securely attached to driver 171 . Support arm 175 is connected to support arm 177 by way of a hinge joint 178 . Cylinder 181 also connects between support arm 175 and support arm 177 . Cylinder 181 is mounted on support arm 175 with a pivot point 183 , and is mounted on support arm 177 with a pivot point 185 .
[0032] The spool 179 position is determined by extending or retracting cylinder 181 . Cylinder 181 could be hydraulically or pneumatically controlled. When cylinder 181 is extended, as in FIG. 8 , the spool would be positioned at a level at or below that of CARS equipment 161 . When the cylinder is compressed, support arm 177 rotates counterclockwise about hinge joint 178 , which in turn raises the spool until it is vertically in line with driver 171 ( FIG. 9 ). When the positioning cylinder is closed, it will bring the hose reel into a position to align the hose with the driver. The hose 187 can then be inserted into the driver 171 and fed into the packoff 167 . The spool 178 is lowered in a similar fashion, with cylinder 181 being extended and support arm 177 rotating clockwise about hinge 178 .
[0033] FIG. 10 illustrates a hose guide assembly 191 for use in a CARS system where the hose reel 201 is placed somewhere remotely, such as, on a platform, or on the ground. The hose 203 is guided into the hose driver 171 by way of a hose guide assembly 191 . The guide assembly is comprised of a curved hose guide tube 193 with a pivoting connector 195 on one end and a hose inlet port 197 on the other. The guide tube 193 is constructed of a solid metal, such as steel pipe. Pivoting connector 195 connects the guide tube 193 to the hose driver 171 . Connector 195 is flexible and allows for pivoting and motion associated with feeding the hose 203 from reel 201 . Inlet port 197 accepts tubing 203 from real 201 . The angle of curvature of guide assembly 191 is such that hosing 203 can easily pass through tubing 193 and enter driver 195 with a vertical orientation.
[0034] The technique has significant advantages. The angled access adapter will allow legacy wells in the field to be modified to allow for connection of a casing annulus remediation system. The angled access port will allow for the casing annulus remediation system hoses to range in flexibility from flexible to rigid, due to the decreased angle of entry into the annulus. Additionally, the curved access adapters allow for a casing annulus remediation system to be implemented in wells located in environments that limit or prohibit standard horizontal entry.
[0035] While the technique has been shown in only one of its forms, it should be apparent to those skilled in the art that it is not so limited but is susceptible to various changes without departing from the scope of the technique.
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An adapter for connecting a casing annulus remediation system to a well having a wellhead with standard lateral ports. The adapter has a body with first and second ends. The first end of the adapter body has a substantially planar surface adapted to cover the lateral ports and be in abutting contact with the wellhead when the two are connected to one another. The second end of the adapter body has a planar surface positioned at an angle greater than 0 degrees and up to 90 degrees to the planar surface of the first end. The second end of the adapter is adapted to be connected to a casing annulus remediation system.
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[0001] This application claims priority from provisional application No. 61/030,987, filed Feb. 24, 2008, the entire contents of which disclosure is herewith incorporated by reference.
BACKGROUND
[0002] Our previous applications and provisional applications, including, but not limited to, U.S. patent application Ser. No. 12/018,069, filed Jan. 22, 2008, entitled “Wireless Apparatus and Methods”, the disclosure of which is herewith incorporated by reference, describe wireless transfer of power. The transmit and receiving antennas are preferably resonant antennas, which are substantially resonant, e.g., within 10% of resonance, 15% of resonance, or 20% of resonance. The antenna is preferably of a small size to allow it to fit into a mobile, handheld device where the available space for the antenna may be limited. An embodiment describes a high efficiency antenna for the specific characteristics and environment for the power being transmitted and received. Antenna theory suggests that a highly efficient but small antenna will typically have a narrow band of frequencies over which it will be efficient. The special antenna described herein may be particularly useful for this kind of power transfer.
[0003] One embodiment uses an efficient power transfer between two antennas by storing energy in the near field of the transmitting antenna, rather than sending the energy into free space in the form of a travelling electromagnetic wave. This embodiment increases the quality factor (Q) of the antennas. This can reduce radiation resistance <R r ) and loss resistance
[0004] In one embodiment, two high-Q antennas are placed such that they react similarly to a loosely coupled transformer, with one antenna inducing power into the other.
[0005] The antennas preferably have Qs that are greater than 200, although the receive antenna may have a lower Q caused by integration and damping.
SUMMARY
[0006] The present application describes antennas for wireless power transfer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] In the Drawings:
[0008] FIG. 1 shows a block diagram with equivalent circuits;
[0009] FIG. 2 shows a measurement set up;
[0010] FIG. 3 shows a first ferrite rod antenna with partial coils;
[0011] FIG. 4 shows a second ferrite rod with a complete coil;
[0012] FIG. 5 shows a plot of resonance frequency; and
[0013] FIG. 6 shows a block diagram of the rod antenna in use.
DETAILED DESCRIPTION
[0014] An embodiment uses ferrites in antennas for transmission and reception of magnetic flux used as wireless power. For example, ferrite materials usually include ceramics formed of MO—Fe 2 O 3 , where MO is a combination of divalent metals such as zinc, nickel, manganese and copper oxides. Common ferrites may include MnZn, NiZn and other Ni based ferrites.
[0015] Ferrite structures concentrate magnetic flux lines into the structure, thereby creating a magnetic path/field with less interference and eddy current losses in device electronics. This in essence sucks in the magnetic flux lines, thereby improving the efficiency of the magnetic power distribution. An embodiment describes a ferrite rod-shaped antennas. These may provide compact solutions that are easy to integrate into certain kinds of packaging. Also, the properties of ferrites may
[0016] The resonance frequency of Ferrite rod antennas may be easier to tune. In one embodiment, the tuning may be carried out by mechanically adjusting the position of the coil on the rod.
[0017] However, Ferrite rod antennas may suffer from Q degradation at higher magnetic field strengths (higher receive power levels) due to increasing hysteresis losses in Ferrite material. The present application describes use of special ferrite antennas to carry out wireless transfer of power.
[0018] The inventors realized that hysteresis losses in ferrite material may occur at higher power receive levels and higher magnetic field strengths. In addition, increasing the magnetic field strength may actually shift the resonance frequency, especially in certain materials where there are nonlinear B-H characteristics in the ferrites. In addition, harmonics emissions can be generated to in due to inherent nonlinearity. This nonlinearity becomes more important at lower Q factors.
[0019] One aspect of the present system is to compare the performance of these antennas, at different power levels and other different characteristics. By doing this, information about the way these materials operate in different characteristics is analyzed.
[0020] Ferrite Rod materials are normally used in communication receiver applications at small signal levels such as at or below 1 mW. No one has suggested using these materials at large levels, e.g. up to 2 W. In order to analyze the characteristics of these materials, measurement values and techniques are described herein. According to one embodiment, the measurement may be carried out at by using the antennas that transmit antenna, and assuming reciprocity as a receiving antenna. The tests increase the V and current, and determine the values of the result.
[0021] According to one embodiment, the Q value is used to determine a limit for the amount of power applied.
[0022] According to one embodiment, the characteristics of a ferrite Rod antenna are evaluated based on the following parameters
Q-factor Resonance frequency Voltage across antenna coil Antenna current Inductance of antenna coil Equivalent permeability of rod Equivalent series resistance Magnetic inductance in Ferrite rod Measurement of tuning range that can be achieved by mechanically tuning of a ferrite rod
[0032] FIG. 1 illustrates the ferrite Rod antenna 100 under test, where the system is formed of a ferrite Rod 102 , on which is wound two different sets of windings. The coupling windings 110 are connected to the electronic circuitry 112 . In this embodiment, the electronic circuitry may be transmitting circuitry, however it should be understood that the electronic circuitry can alternately be receiving circuitry. Accordingly, the circuitry 112 is referred to herein as power converting circuitry. The power circuitry 112 is formed of an AC part, for example and AC generator, with a matching impedance 116 . The matching impedance 116 is connected to a first wire 108 of the twisted-pair 111 . The second wire 109 of the twisted-pair 111 goes to ground. The two wires 108 , 109 are collectively connected to a coupling windings 120 . Coupling winding 110 is located at a 1st place on the ferrite Rod 100 to. The coupling winding 110 is completely separated from the main winding 120 . Moreover, the number of windings of the coupling winding 110 may be ⅕ to 1/10 the number of windings of 120 . The important part is to induce magnetic flux into the ferrite Rod, without having the impedance of the inducement changed by any external characteristics.
[0033] The main winding 120 is also in parallel with a main capacitor 125 .
[0034] A number of different values within the FIG. 1 embodiment may be measured. For example, these values may include
[0000] U 0 : Source voltage (e.m.f.) of LF power source [V] Z out : Output (source) impedance of LF power source [Ω] U in : Input voltage measured at antenna terminals a/b [V] I in : Input current measured at antenna terminals a/b [A] Z in : Input impedance measured at antenna terminals a/b [Ω] I A : Antenna current (r.m.s.) [A] U c : Voltage across antenna capacitance (r.m.s.) [V] P in : Antenna input power [W] L: Equivalent inductance of Ferrite rod antenna [H] (includes all reactive components except C) C: Capacitance required to achieve resonance frequency [F] R s : Equivalent series resistance of Ferrite rod antenna [Ω] (includes all losses except source resistance) U 0 ′: Source voltage transformed into equivalent series circuit [V] R out ′: Source resistance transformed into equivalent series circuit [Ω] Q UL : Unloaded Q-factor μ rod : Effective relative permeability of Ferrite rod B rod : Computed magnetic flux density (induction) in Ferrite rod [T] N: Number of turns A Fe : Ferrite cross sectional area [m 2 ]
The different characteristics can also be determined from these values, as
[0035] 2.2.2.2 Equations
[0036] Resonance Frequency:
[0000]
f
res
=
1
2
π
L
·
C
Equation
2
-
1
[0037] Unloaded Q-Factor:
[0000]
Q
UL
=
1
R
s
L
C
=
2
π
f
L
R
s
Q
UL
=
2
π
·
f
·
C
·
U
c
2
P
i
n
Equation
2
-
2
[0038] Input Power:
[0000] follows
[0000] P in =Re{U in ·I in } Equation 2-3
[0039] Effective Relative Permeability of Ferrite Rod
[0000]
μ
rod
=
L
L
air
Equation
2
-
4
[0040] Magnetic Flux Density (Inductance) in Ferrite Rod:
[0000]
B
rod
=
U
C
π
·
2
·
N
·
A
Fe
·
f
Equation
2
-
5
[0041] FIG. 2 illustrates the ways of measuring the different values, shown as channel 1 , channel 2 and Channel 3 . These different values can be measured as follows
Oscilloscope: measures r.m.s. of U in (CH 1 ), I in (CH 2 ), U C (CH 3 ) T1: Current transformer, toroid Epcos R16/T38, 25 turns R1: Load resistor of T1(R1//R(CH 2 )=25 . . . 100 Ohm, 25 Ohm: 1 A current→1V at CH 2 ) AMP1: Amplifier arcus 100 W, voltage gain=33 (135 kHz) R2: Load resistor of AMP1, 5 . . . 50 Ohm (needed for safety and stability of the amplifier) T2: Isolation transformer 1:1 (2*40 turns bifilar, Epcos R16/T38 toroid) to prevent from ground loop interference ATT1: Attenuator 50 Ohm, 10 . . . 20 dB to prevent from overload of AMP1 GEN1: RF signal generator (Rohde&Schwarz SMG)
[0050] According to a measurement procedure, the generator is started with −10 DBM of power, and at a frequency that is resonant to the calculated resonant frequency from the equation 2.1. At this resonant frequency, all of the signals U in , I in and U c are in phase so long as the polarities of channel 1 and Channel I mean channel 2 and Channel 3 is correct and the current channel (Ch 2 ) has a minimum value.
[0051] The values of U in , I in and U c are measured at the resonant frequency.
[0052] The remaining values are calculated.
[0053] Table 1 represents the results for an “X” antenna made using ferrite materials. The measured values are used to calculate certain other values within this antenna.
[0054] This antenna shown in FIG. 3 has a length of 87 mm, and a diameter of 10 mm. The ferrite material used is Ferroxcube 4B2. The main coil of this antenna has 19 windings of main coil 300 for a total length of 20 mm of 300×0.4 mm wire. A three turn coupling coil 302 is connected to receive the magnetic resonant field from a generator 305 . The coupling coil 302 is spaced along the rod at 12 mm from the end of the main coil. A 55.17 nF 500V Mica capacitor 310 is used to form resonance. Q values are
[0055] A number of measurements were carried out as shown in Table 1, where the left side of the table represents the inputs to the coil. Based on these inputs, and the equations noted above, the values on the right side of the table were calculated.
[0000]
TABLE I
Input (measured)
Calculation
Meas
f res
U in
I in
Uc
P in
Z in
L
#
kHz
V rms
mA rms
V rms
mW
Ohm
μH
8
134.98
0.00818
0.1406
0.0888
0.0012
58.179
25.200
7
134.97
0.0259
0.511
0.284
0.0132
50.685
25.204
6
134.9
0.0784
1.67
0.861
0.131
46.946
25.230
1
134.920
0.075
1.450
0.733
0.109
51.724
25.222
2
134.752
0.228
5.270
2.260
1.202
43.264
25.285
3
134.294
0.643
18.440
6.370
11.857
34.870
25.458
4
133.113
1.555
68.070
17.140
105.849
22.844
25.912
5
131.011
3.450
244.400
37.050
843.180
14.116
26.750
Calculation
Meas
X
Q UL
I A
R s
μ rod
B rod
R p
#
Ohm
U
mA rms
Ohm
U
mT peak
Ohm
8
21.372
320.804
4.155
0.0666
12.632
0.099
6856.3
7
21.374
285.126
13.287
0.0750
12.633
0.318
6094.2
6
21.385
264.770
40.262
0.0808
12.647
0.963
5662.1
1
21.382
231.067
34.282
0.0925
12.643
0.820
4940.6
2
21.408
198.559
105.567
0.1078
12.674
2.531
4250.8
3
21.481
159.311
296.537
0.1348
12.761
7.159
3422.2
4
21.672
128.067
790.886
0.1692
12.988
19.434
2775.5
5
22.020
73.934
1682.592
0.2978
13.408
42.683
1628.0
[0056] The table shows that the Q value stays greater than 100 up to a power level of approximately 100 mw. The 840 mw measurement showed a Q of 73 , and a resonant frequency that has shifted by almost 4 Khz from the value it shows at 10 −3 mw. Note again, as discussed
[0057] According to one embodiment, therefore, the antenna is only operated in regions where it has specific values that are within the desired values of operation of the antenna, e.g, high enough Q, proper frequency, etc.
[0058] A second embodiment used an antenna as shown in FIG. 4 . This used a similar sized rod formed of similar material. Antenna 400 uses 75 turns of wire 405 and a two-turn coupling coil 410 , located over the main coil, at 25 mm from the end of the main coil. This antenna uses a 6.878 nF 400 V polypropylene capacitor 415 .
[0059] Table 2 represents second measured and calculated results for the FIG. 4 antenna.
[0000]
Input (measured)
Calculation
Meas
f res
U in
I in
Uc
P in
Z in
L
X
Q UL
I A
R s
μ rod
B rod
R p
#
kHz
V rms
mA rms
V rms
mW
Ohm
μH
Ohm
U
mA rms
Ohm
U
mT peak
Ohm
1
133.601
0.0274
0.38
0.895
0.0104
72.105
206.328
173.200
444.185
5.187
0.3889
23.235
0.258
76932.9
2
133.541
0.0828
1.265
2.684
0.1047
65.455
206.514
173.278
396.918
15.490
0.4366
23.256
0.768
68777.1
3
133.333
0.2336
4.462
7.68
1.042
52.353
207.159
173.548
326.062
44.253
0.5323
23.329
2.201
58587.4
4
132.763
0.610
17.240
19.710
10.518
35.389
208.941
174.293
211.911
113.085
0.8225
23.529
5.673
36934.7
5
131.504
1.404
65.100
45.860
91.400
21.567
212.961
175.962
130.768
260.624
1.3456
23.982
13.325
23010.2
6
129.342
2.882
247.000
94.650
711.854
11.668
220.140
178.903
70.345
529.057
2.5432
24.791
27.962
12584.9
7
127.234
4.720
652.000
149.200
3077.440
7.239
227.495
181.867
39.773
820.378
4.5726
25.619
44.807
7233.5
|
A wirelessly-powered device that uses a ferrite based antenna. The ferrite antenna can be tuned to reduce the amount of flux within the housing.
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This is a Division of application Ser. No. 08/116,277 filed Sep. 3, 1993 U.S. Pat. No. 5,427,890, which in turn is a continuation of Ser. No. 07/668,520, filed Mar. 28, 1991, now abandoned.
TECHNICAL FIELD
The present invention relates to a method for forming images by engraving through sand blasting or by etching with chemicals, for instance, solutions of etching agents through an image-carrying mask such as picture images, patterns or letters on the surface of materials to be processed such as glass, stone, pottery, metals, plastics, wooden materials and leather as well as a photo-sensitive laminate film for use in making such an image-carrying mask.
BACKGROUND ART
Conventionally known methods for processing the surface of a material such as glass, a metal or a plastic by engraving images on the surface comprise the steps of first forming a resist layer, in the form of images, on the surface of a material to be processed and then subjecting the entire surface inclusive of the surface of the resist layer to sand blasting to thus engrave the surface on which any image is not present and to thereby form the images thereon. When the material to be processed is glass, a treatment of the surface with hydrofluoric acid can be substituted for the sand blasting treatment and thus desired images can be formed on the surface through engraving and/or etching of the surface portion on which any image is not present. On the other hand, when the material to be processed is a copper plate, the surface can also be treated with an aqueous solution of ferric chloride and thus the desired images can be formed through engraving and/or etching of the surface portion on which any image is not present.
The formation of a resist layer can be performed according to a method which comprises printing desired images on the surface of a material to be processed with a resist ink according to the screen printing method to thus form a resist layer in the form of desired images. Alternatively, a resist layer can also be formed by likewise printing images on the surface of a non-woven fabric of glass fibers according to the screen printing method and then adhering the resulting non-woven fabric carrying the printed images to the surface of a material to be processed.
Moreover, there have been proposed a variety of methods for preparing image-carrying masks using liquid photo-sensitive resins. For instance, Japanese Patent Publication for Opposition Purpose (hereunder referred to as "J. P. KOKOKU") No. Sho 46-35681 discloses a method for producing an image carrying mask which comprises the steps of enclosing a predetermined surface area of a material to be processed such as glass with a rubber frame, directly pouring a photo-sensitive resin into the enclosed area, covering the area with a cellophane film, exposing the resin to light through a negative film carrying pictures and/or patterns, peeling off the cellophane film and then developing the imagewise exposed photo-sensitive resin to thus form a resist layer carrying the desired images.
Japanese Patent Unexamined publication (hereunder referred to as "J. P. KOKAI") No. Sho 53-99258 discloses a method for producing an image-carrying mask which comprises sandwiching a liquid photo-sensitive resin composition between two transparent films to form a photo-sensitive resin composition between two transparent films to form a photo-sensitive layer, exposing the liquid photo-sensitive resin layer to light while coming the composition in close contact with a photomask carrying desired pictures and/or patterns, peeling off the transparent film on the side of the photomask, removing the unexposed areas of the layer to thus give the desired image, adhering the resulting photo-sensitive resin layer on which the images are thus formed to the surface of a material to be processed so that the face of the former on the photomask side opposes to the surface of the material and peeling off the remaining transparent film.
J. P. KOKAI No. Sho 55-96270 discloses a method which comprises the steps of putting a molding frame which also serves as a spacer on a support layer (for instance, a polyester film having a thickness of 100 μm) capable of being treated by sand-blasting, pouring a liquid photo-sensitive resin (100% modulus of the resin photo-hardened=500 kg/cm 2 ) into the area defined by the molding frame, exposing the resin to light through a film carrying pictures and/or patterns, developing the exposed resin to thus give a mask carrying the images which comprises photo-hardened photo-sensitive resin layer having through holes corresponding to the images, applying a rubber paste to the reverse face of the support and then adhering the resulting product to the surface of a material to be processed. In addition, J. P. KOKAI No. Sho 60-104939 discloses a transfer material for forming a mask for sand blasting which comprises a layer carrying a mask-pattern formed from a liquid photo-sensitive resin composition in which the molecular structure and the properties of its components are specified; a substrate layer for supporting the layer carrying the mask-pattern; and a support layer which is placed between the layer carrying the mask-pattern and the substrate layer, which can be well-adhered to the layer carrying the mask-pattern but is capable of being peeled off from the substrate layer and which can be destroyed through sand blasting. In the washing away development of these photo-sensitive resin compositions, it is needed to use an organic solvent such as acetone or benzene; an alkaline aqueous solution such as an aqueous sodium hydroxide or sodium borate solution; an alcoholic solution of calcium chloride or an aqueous solution of a surfactant such as a neutral detergent as a developer.
The present invention has been completed under such circumstances and the object of the present invention is to provide a method for engraving or etching images with a mask carrying such images as well as a photo-sensitive laminate film for use in making a mask carrying images, which makes it possible to easily and precisely form fine precise images on a mask according to the photoprinting technique in the production of such a mask which is used when images are engraved or etched on the surface of a material to be processed such as glass, a metal or a plastic; which can be handled in the form of a film; which can easily be exposed to light and developed; which can be developed with a developer simply comprising water and whose handling is thus safe and economical; whose surface carrying images obtained after development has strong adhesion and thus can be adhered to the surface of a material to be processed without using any adhesive to thus transfer images to the material; whose substrate can easily be peeled off after fine pictures and/or patterns are transferred to the material to thus prevent the aberration of the position of an image; and which makes it possible to prevent the removal of fine portions of images during sand blasting to thus allow precise engraving and/or etching.
DISCLOSURE OF THE INVENTION
The method for engraving and/or etching a material according to the present invention for achieving the foregoing object comprises the following steps (a) to (e): (a) a process for exposing, to light, a layer of a water-soluble resin composition of a photo-sensitive laminate film which comprises a supporting sheet, an image mask-protection layer peelablly adhered to the supporting sheet and a water-soluble resin composition layer having photocrosslinkability to thus cause crosslinking of the exposed areas of the resin layer to thereby form a predetermined pattern on the resin layer; (b) a process for dissolving out the non-crosslinked area on the layer of the water-soluble photo-sensitive resin composition by developing the layer with water to thus form a mask carrying the images which is constituted from the crosslinked areas of the photo-sensitive resin composition remaining on the image mask-protection layer; (c) a process for adhering the photo-sensitive laminate film on which the images are formed to the surface of a material to be processed; (d) a process for peeling off the supporting sheet from the photo-sensitive laminate film; and (e) a process for engraving and/or etching the material to be processed through the image-carrying mask adhered to the material. According to the foregoing processes, fine and precise images can be easily and precisely formed on a material to be processed through the photo-duplicating method. In addition, exposure and development processings are very simple since the photo-sensitive material is in the form of a film. Moreover, the development processing is safe and economical since it is performed with a developer simply comprising water. The surface of the image-carrying mask obtained after development exhibits strong adhesion and correspondingly the mask can be adhered to the material to be processed without using any adhesive. Further, the supporting sheet can easily be peeled off because of a presence of the image mask-protection layer after fine pictures and/or patterns are transferred to the material to thus prevent the aberration of the position of images and the removal of fine portions of the images can be prevented during sand blasting. Thus, the precise engraving and/or etching of a desired patterns and/or pictures can be performed.
In the method of the present invention, the treatment with water in the process (b) is preferably performed by previously immersing the photo-sensitive laminate film which has been exposed to light through a pattern to swell the non-crosslinked portion on the layer of the water-soluble resin composition and then washing with water. Thus, the non-crosslinked portion on the layer of the water-soluble resin composition can be completely be removed and hence clear images can be obtained.
In the process (c), the photo-sensitive laminate film is preferably adhered to a material to be processed while applying a pressure or heating the same. Alternatively, the process (c) can be performed by applying, to the layer of the crosslinked water-soluble resin composition, an aqueous solution of sodium periodate, lithium chloride, lithium bromide, lithium nitrate, calcium chloride or ammonium thiocyanate to swell or solubilize the layer and then adhering the photo-sensitive laminate film to the material to be processed under pressure.
The process (e) for engraving or etching the material to be processed is preferably performed according to engraving or etching through sand blast. Likewise, the process (e) may be performed according to the engraving or etching with a chemical.
The photo-sensitive laminate film used in the method for engraving or etching a material to be processed comprises a supporting sheet, an image mask-protection layer peelablly adhered to the supporting sheet and a layer of a water-soluble resin composition having photocrosslinkability. The water-soluble resin composition having photocrosslinkability of the photo-sensitive laminate film for use in making an image carrying mask is a composition comprising a water soluble polymer and a photocrosslinking agent and preferably comprises a composition selected from the group consisting of a composition which comprises polyvinyl alcohol and a sulfate, hydrochloride, nitrate or phosphate of a condensate of 1-diazophenylamine with paraformaldehyde; a composition comprising polyvinyl pyrrolidone and sodium 4,4-bisazidostilbene-2,2'- disulfonate; and a composition comprising polyvinyl methyl ether and mono(di)acryloxyethyl phosphate. The water-soluble resin composition having photocrosslinkability may be a composition comprising a water-soluble polymer having a photocrosslinkable groups in the molecule selected from polyvinyl alcohol which is subjected to modification with acetal to introduce stilbazolium groups therein and polyvinyl alcohol to which N-methylolacrylamide is added. The layer of the water-soluble resin composition having photocrosslinkability preferably has a thickness ranging from 0.03 to 2 mm. If the thickness of the layer is limited to the range defined above, the image-mask obtained after development of the layer exhibits sufficient resistance to the sand blasting or etching with a chemical during the process for engraving or etching the material to be processed. The image mask-protection layer of the photosensitive laminate film for making an image-carrying mask is preferably prepared from a member selected from the group consisting of polyvinyl alcohol, polyvinyl alcohol derivatives, polyvinyl butyral, ethyl cellulose, cellulose acetate and cellulose nitrate. Moreover, the image mask-protection layer is made from a material different from that for the supporting sheet and may be obtained from a member selected from the group consisting of polyvinyl chloride, polystyrene and polyamide. If the material for forming the image mask-retention layer is limited to these specific ones, the image mask-protection layer is weakly adhered to the supporting sheet during the development processing and can easily be peeled off therefrom, while it is relatively strongly adhered to the layer of the water-soluble resin composition, i.e., to the image-carrying mask. The thickness of the image mask-protection layer preferably ranges from 1 to 30 μm. This is because, if the thickness thereof falls within the range defined above, the image-carrying mask can be supported by the layer without causing any breakage and the mask can easily be removed during the process for engraving and/or etching the material to be processed without any difficulty.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a cross-sectional view of the photo-sensitive laminate film for image-masks according to the present invention; and FIGS. 2 to 10 are diagrams for illustrating, in order, the method for engraving and/or etching with the aid of an image-carrying mask according to the present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
The preferred embodiments of the present invention will hereunder be explained in more detail, but the present invention is not restricted to these specific embodiments at all.
FIG. 1 shows the construction of the photo-sensitive laminate film for an image-carrying mask used in the method for engraving and/or etching a material with the used of such an image-carrying mask according to the present invention. In the photo-sensitive laminate film 10 for an image-carrying mask, an image mask-protection layer 12 is adhered to a supporting sheet 11 obtained from a polyester film having a thickness of 75 μm. The image mask-protection layer 12 comprises a layer of ethyl cellulose having a thickness of about 5 μm formed according to a coating technique. A layer 13 of a water-soluble resin composition having photocrosslinkability having a thickness of 80 μm is formed on the image mask-protection layer 12, the layer 13 being formed by coating a solution containing polyvinyl alcohol, an ethylene/vinyl acetate copolymer resin, a diazo resin, a water-dispersible pigment and a non-ionic surfactant, i.e., polyoxyethylene laurylphenyl ether and then drying the coated layer.
The method for engraving and/or etching a material with an image-carrying mask according to the present invention can be practiced with the aid of the photo-sensitive laminate film 10 for making an image-carrying mask in accordance with the processes as shown in the attached FIGS. 2 to 10. As is shown in Fig.2, an original positive film 15 carrying fine pictures and patterns comes in close contact with the surface of the water-soluble resin composition-layer 13 of the photo-sensitive laminate film 10 and is irradiated with light 16 from a metal halide lamp. Then, as shown in FIG. 3, the original positive film 15 is peeled off from the photo-sensitive laminate film 10. If the exposed photo-sensitive laminate film 10 is immersed in water 17, the exposed portion thereof 13a is not swollen since it is crosslinked, but non-crosslinked unexposed portion 13b gets swollen and is soluble in water as shown in FIG. 4. As shown in FIG. 5, if water 19 is sprayed with a spraying device 18 to wash away the unexposed portion, only the exposed portion 13a remains as an image-carrying mask and the laminate film is thus developed. The resulting product is hot-air dried to give an image-carrying mask 13a on the image mask-protection layer 12 which is put on the supporting sheet 11.
As is shown in FIG. 6, the image-carrying mask 13a which is still supported by the supporting sheet 11 and the image mask-protection layer 12 is adhered and contact-bonded to a glass plate 20 while heating with an iron 21. Then, as shown in FIG. 7, the supporting sheet 11 is peeled off from the image mask-protection layer 12. Further, as shown in FIG. 8, the glass plate is engraved or etched by blasting abrasive particles 23 through the image mask-protection layer 12 using a sand blasting machine 22. Thus, the portion of the glass plate 20 to which the image-carrying mask 13a is adhered is not engraved and/or etched, while on the portion of the glass plate to which the image-carrying mask 13a is not adhered or which is covered with only the image mask-protection layer 12 is engraved and/or etched, the image mask-protection layer 12 is completely removed and the surface of the glass plate 20 is engraved and etched as shown in Fig. 9. After the completion of the sand blasting operation, the remaining abrasive 23 and the image-carrying mask 13a are washed out so that the glass plate 20 on which the image is engraved or etched is completed as shown in FIG. 10.
The following variations can be made to the foregoing embodiment.
As the supporting sheet 11, there may be used, for instance, a polypropylene film, a polyethylene film, a polystyrene film, a polyvinyl chloride film, a polycarbonate film, synthetic paper or paper coated with a synthetic resin in addition to the polyester film used in the embodiment. Moreover, the thickness of the supporting sheet 11 may be adjusted within the range of from 50 to 500 μm.
In the foregoing embodiment, the layer 13 of the water-soluble resin composition used has a thickness of 80 μm. However, the thickness thereof may be varied between 0.03 to 2 mm and it is thus preferred to properly control the thickness thereof depending on the depth to be engraved and/or etched so that the image-carrying mask obtained after development shows proper resistance to sand blasting or chemicals. If the depth to be engraved is great, the thickness thereof should be adjusted within the range of from 0.1 to 2 mm so as to withstand the processing over a long time period, while if the depth to be engraved is small, it is sufficient to adjust the thickness to 30 to 80 μm.
In the foregoing embodiment, the exposure process shown in FIG. 2 is performed by irradiating with the light 16 from a metal halide lamp, but it is also possible to use other light sources which emit actinic rays having a wave length ranging from 300 to 500 nm such as an arc lamp, a xenon lamp or a high pressure mercury lamp.
The development processing as shown in FIG. 5 is carried out by spraying water 19 using a spraying machine 18, but it is also effective to lightly rub the surface with a brush or a sponge simultaneously with such a spraying operation to wash out the non-exposed portion and to thus develop the laminate film.
In the process shown in FIG. 8, the engraving or etching process is performed by blasting the abrasive particles 23 with the aid of the sandblasting machine 22, but the etching with a chemical is likewise effective. Examples of chemicals used in the engraving or etching treatment are an aqueous solution of hydrofluoric acid when the materials to be processed are glass and stones, an aqueous solution of ferric chloride when the materials are copper and copper alloys, and aqueous solutions of hydrochloric acid and sulfuric acid when they are other metals.
The present invention will hereunder be explained in more detail with reference to the following specific examples.
EXAMPLE 1
15 parts by weight of polyvinyl alcohol having an average degree of polymerization of 1,700 and a degree of saponification of 88 mole % (available from Shin Etsu Chemical Co., Ltd. under the trade name of PA-18) was dissolved in 85 parts by weight of water. To the resulting solution, there were added 120 parts by weight of an ethylene-vinyl acetate copolymer emulsion having a solid content of 50% by weight (available from Showa Highpolymer Co., Ltd. under the trade name of EVA AD-50), 5 parts by weight of a diazo resin, 0.2 part by weight of a water-dispersible blue pigment and 1 part by weight of a non-ionic surfactant, i.e., polyoxyethylene laurylphenyl ether followed by mixing of these to give a mixed solution for forming a layer of a photo-sensitive resin composition. A polyester film having a thickness of 75 μm was provided as a supporting sheet. A solution obtained by dissolving ethyl cellulose ("Ethocell STD-10" available from Dow Chemical Co., Ltd.) in a 1:1 mixed solvent of ethyl alcohol and toluene so that the concentration of the ethyl cellulose was 10% by weight was applied onto the supporting sheet and then dried to give an image mask-protection layer having a thickness of about 5 μm (determined after drying). The mixed solution of the photo-sensitive resin composition prepared above was applied onto the image mask-retention layer and dried to give a photo-sensitive laminate film comprising a layer of the photo-sensitive resin composition having a thickness of 80 μm.
An image-carrying mask was prepared from the photo-sensitive laminate film thus prepared. An original positive film was closely put on the layer of the photo-sensitive resin composition of the photo-sensitive laminate film and the resulting assembly was exposed to light from a 3 KW metal halide lamp at a distance of 1 m. Then the exposed film was developed by immersing in water maintained at ordinary temperature for 3 minutes to let the film absorb water and to thus swell the same, then lightly rubbing with a sponge and washing out to retain only the exposed portion. The developed product was dried with hot air of 50° C. to give an image-carrying mask which carried fine pictures and/or patterns and which had still supported by the image mask-protection layer and the supporting sheet. There was not observed any separation between the supporting sheet and the image mask-protection layer and between the image mask-protection layer and the image-carrying mask during the development processing.
The image-carrying mask was adhered to a glass plate having a thickness of 8 mm and subjected to contact bonding while applying heat with an iron through the supporting sheet. Then the supporting sheet was peeled off from the image mask-protection layer. The supporting sheet was easily separated from the image mask-protection layer, but the adhesion between the image mask-protection layer and the image-carrying mask was strong and, therefore, there was not observed any aberration of the relative position between the image-carrying mask and the glass plate.
The assembly thus obtained which comprised the glass plate, the image-carrying mask directly adhered to the glass plate and the image mask-protection layer was fixed in a sandblasting machine and an abrasive, Alundum #80, was blasted on the glass plate through the image-carrying mask at a compressed-air pressure of 4 kg/cm 2 through a nozzle having a diameter of 3.6 mm at a distance of about 20 cm to thus perform engraving of the glass plate. The image-carrying mask was not peeled off and was not damaged at all and the surface of the glass plate to which the image-carrying mask had been adhered was not impaired even when the abrasive was blasted on the assembly for 30 seconds. On the other hand, when the abrasive was blasted on the assembly for 10 seconds, the image mask-protection layer was completely removed from the portion of the glass plate which was covered with only the image mask-protection layer and the glass surface was engraved to a depth of about 1 mm. After the completion of the sand blasting operation, the remaining image-carrying mask sufficiently got swollen with water and then washed away. Thus, the fine picture and patterns of the original were faithfully engraved on the glass plate.
EXAMPLE 2.
There was dissolved, in water, a stilbazolium-added polyvinyl alcohol which was prepared by subjecting, to a reaction with acetal, polyvinyl alcohol having an average degree of polymerization of 1,700 and degree of saponification of 88 mole % (available from Shin Etsu Chemical Co., Ltd. under the trade name of PA-18) to add 1.4 mole % of N-methyl-γ-(p-formylstilyl)-pyridinium methosulfate to thus give a solution having a concentration of 15% by weight. 15 parts by weight of an acrylate oligomer (available from Toagosei Chemical Industry Ltd. under the trade name of Aronix M-8030), 15 parts by weight of pentaerythritol triacrylate and 3 parts by weight of 2-chlorothioxanthone (available from Nippon Kayaku Co., Ltd. under the trade name of Kayacure CTX) were added to and dispersed in the foregoing solution. 55 parts by weight of a 50% by weight polyvinyl acetate emulsion and 0.2 part by weight of a water-dispersible purple pigment were added to and mixed with the resulting dispersion to thus prepare a mixed solution of a photo-sensitive resin composition. This mixed solution of the photo-sensitive resin composition was applied onto the surface of an image mask-protection layer applied to a supporting sheet similar to those used in Example 1 and then dried to give a photo-sensitive laminate film carrying a layer of the photo-sensitive resin composition having a thickness of 100 μm.
The same procedures used in Example 1 were repeated to give an image-carrying mask using the photo-sensitive laminate film. There was not observed any separation between the supporting sheet and the image mask-protection layer and between the image mask-protection layer and the layer of the photo-sensitive resin composition, i.e., the image-carrying mask during the development processing.
The image-carrying mask thus obtained which had been still carried by the supporting sheet and the image mask-protection layer was adhered to a glass plate having a thickness of 8 mm on which a 1% aqueous solution of sodium periodate was coated and subjected to contact bonding. Then the supporting sheet was peeled off from the image mask-protection layer. The supporting sheet was easily be separated from the image mask-protection layer, but the adhesion between the image mask-protection layer and the image-carrying mask was strong and, therefore, there was not observed any aberration of the relative position between the image-carrying mask and the glass plate.
A 50% by weight aqueous solution of hydrofluoric acid was applied onto the surface of the resulting assembly which comprised the glass plate, the image-carrying mask adhered to the glass plate and the image mask-protection layer on the image-carrying mask, on the side of the image mask-protection layer. After about 2 minutes, the assembly was sufficiently washed with water to wash out the aqueous hydrofluoric acid solution as well as the remaining image-carrying mask. The portion of the glass plate to which the image-carrying mask had been adhered was not corroded with the hydrofluoric acid aqueous solution. On the other hand, the image mask-protection layer was approximately easily be removed and the portion of the glass plate to which any image-carrying mask had not been adhered, i.e., that covered with only the image mask-protection layer was corroded and dissolved out to a depth of about 50 μm. Thus, the fine picture and patterns of the original were faithfully etched on the glass plate.
INDUSTRIAL APPLICABILITY
According to the method for engraving and/or etching according to the present invention, fine and precise images can be engraved and/or etched on the surface of a material to be processed such as glass, metals and plastics. The photo-sensitive laminate film for making an image-carrying mask used in the engraving and/or etching method can be handled in the form of a film during preparing the image-carrying mask and thus the handling thereof during the exposure to light and the development is very simple. In addition, since the development thereof can be performed with a developer simply comprising water, the film is safe and economical. The image-carrying mask obtained after development can be adhered to a material to be processed without using any adhesive since the surface thereof has adherence and does not cause the aberration of the position relative to the material to be processed even if it carries fine pictures and patterns because of a presence of the image mask-protection layer. Moreover, the image mask-protection layer serves to prevent the separation of fine portions of the image during the sand blasting operation and as a result, precise engraving can be performed.
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A method for engraving and/or etching comprising the steps of: (a) a process for exposing, to light, a layer of a water-soluble resin composition of a laminated photo-sensitive film which comprises a supporting sheet, a image mask-protection layer peelablly adhered to the supporting sheet and a layer of a water-soluble resin composition having photocrosslinkability to thus cause crosslinking of the exposed area of the resin layer to thereby form a predetermined pattern on the resin layer; (b) a process for dissolving out the non-crosslinked portion of the layer of the water-soluble photo-sensitive resin composition by developing the layer with water to thus from an image-carrying mask which is constituted from the crosslinked area of the photo-sensitive resin composition remaining on the image mask-protection layer; (c) a process for adhering the photo-sensitive laminate film on which the images are formed to the surface of a material to be processed; (d) a process for peeling off the supporting sheet from the photo-sensitive laminate film; and (e) a process for engraving and/or etching the material to be processed through the image-carrying mask adhered to the material, makes it possible to engrave and/or etch fine and precises images on the surface of a material to be processed such as glass, metals, plastics or the like.
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RELATED APPLICATION INFORMATION
The present application claims priority to and the benefit of German patent application no. 10 2012 209 384.2, which was filed in Germany on Jun. 4, 2012, the disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
The present invention relates to control methods for position transducers, in particular adaptive control methods for position control of a position transducer.
BACKGROUND INFORMATION
The position of actuators in position transducer systems in an internal combustion engine is generally ascertained with the aid of a control method as a function of one or more internally or externally predefined setpoint variables. However, manufacturing tolerances as well as environmental influences and aging result in the response of the actuator and of the position transducer system deviating from the expected response or if there are changes in same. The position transducer system to be controlled thus changes as a function of its operating conditions.
In general, a control method should achieve a compromise between all possible states of the actuator, so that the control system achieves a good response with respect to bandwidth, stability, precision and robustness in all operating states. However, adapting the control method and its control parameters to a position transducer having certain properties results in an undesirable system response when the tolerances and the environmental effects on and aging of the actuator become too great and therefore the properties of the position transducer differ too much from those of a position transducer to which the control method and its control parameters are adapted. It is therefore necessary to adapt the control accordingly to achieve an optimal system response over the entire lifetime of the position transducer.
Publication WO 2007/096327 A1 discusses an adaptive control method for a throttle valve in which a pilot control is adapted as a function of measured operating conditions, for example, temperature, air mass flow and pressure drop across a throttle valve.
Publication U.S. Pat. No. 6,668,214 discusses an adaptive control method having online parameter identification. The identified parameters are used to compensate for dead time in the control loop and to adapt a sliding mode controller.
SUMMARY OF THE INVENTION
According to the present invention, a method for operating a controller of a position transducer system, in particular a throttle valve position transducer in an engine system having an internal combustion engine according to the description herein is provided, and a control device and a computer program product according to the other descriptions herein are also provided.
Additional advantageous embodiments of the present invention are stated in the further descriptions herein.
According to a first aspect, a method for operating a controller for a position transducer system is provided, the control being carried out to obtain a manipulated variable for triggering an actuating drive of the position transducer system, the control being carried out by initially applying a transfer function to a system deviation to obtain an adapted system deviation and subsequently a transfer function is applied to the adapted system deviation to obtain the manipulated variable, the transfer function being a function which indicates a deviation of a model of a nominal position transducer system having predefined nominal parameters from the model of the position transducer system to be controlled, an adaptation of the control process being carried out by adapting the transfer function in that the parameters of the model of the position transducer system to be controlled are adapted.
One aspect of the above method is to configure the controller of the position transducer system in such a way that an adaptation is carried out in that a system deviation is adapted before a transfer function is applied. For this purpose, the transfer function is adapted to a transfer function for adaptation of the system deviation so that the adapted system deviation takes into account only the deviation of the response of the physical position transducer system from a reference position transducer system or a nominal position transducer system, while the transfer function is configured for the reference position transducer system or the nominal position transducer system in accordance with the control process. The control parameters used there may be disregarded in an adaptation of the control process. This has the advantage that an adaptation of the control process may be carried out rapidly and without intervention into the control process in that merely the transfer function using the model parameters of the position transducer system, which change due to the change in the physical response of the position transducer system, may be adapted.
In addition, the transfer function may be a control function having constant predefined control parameters, which have been ascertained with respect to a nominal position transducer system and are invariant for the adaptation of the control process.
In particular it may be provided that only linear components are taken into account as the model of the nominal position transducer system and as the model of the position transducer system to be controlled.
According to one specific embodiment, the transfer function may also take into account a pilot control variable which is ascertained as a function of an inverse model of the position transducer system to be controlled and of the model parameters which are ascertained and adapted online.
In addition, a nonlinear component of the model of the position transducer system to be controlled may be taken into account in the pilot control to compensate for nonlinearities in the position transducer system.
It may be provided that the transfer function is implemented as a discrete recursive equation with the aid of Tustin's method.
According to another aspect a control system for operating a controller for a position transducer system is provided, the control being carried out to obtain a manipulated variable for triggering an actuating drive of the position transducer system, including
an adaptive filter to apply a transfer function to a system deviation in order to obtain an adapted system deviation, the transfer function representing a function which indicates a deviation of a provided model for a nominal position transducer system using predefined nominal parameters from a provided model of the position transducer system to be controlled, a control block to apply a transfer function to the adapted system deviation to obtain the manipulated variable,
the adaptive filter being configured to adapt the model of the position transducer system to be controlled in accordance with providable model parameters.
According to another aspect, a computer program having program code means is provided to carry out all steps of the above method when the computer program is executed on a computer or an appropriate arithmetic unit, in particular in the above control system.
According to another aspect, a computer program product is provided, containing program code which is stored on a computer-readable data medium and carries out the above method when executed on a data processing system.
Specific embodiments of the present invention are explained in greater detail below on the basis of the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a schematic diagram of a position transducer system using the example of a throttle valve position transducer.
FIG. 2 shows a function diagram to illustrate a position control for the position transducer of FIG. 1 .
FIG. 3 shows a function diagram to illustrate the creation of the manipulated variable for the position control of FIG. 2 .
FIG. 4 shows a function diagram to illustrate a prefilter and a pilot control for generating the manipulated variable of the position control of FIG. 2 .
FIG. 5 shows a function diagram to illustrate the control unit for generating the manipulated variable.
FIG. 6 shows a flow chart to illustrate a method for generating the prefilter signals and the pilot control signals.
FIG. 7 shows a flow chart to illustrate a method for generating the manipulated variable for controlling a position transducer system via a throttle valve position transducer according to FIG. 1 .
FIG. 8 shows a diagram to illustrate a spring characteristic line for a return spring of a position transducer system of FIG. 1 .
DETAILED DESCRIPTION
FIG. 1 shows a schematic diagram of a position transducer system 1 using the example of a throttle valve position transducer system. Position transducer system 1 has a throttle valve situated in a gas carrying line 3 as actuator 2 . The actuator is movable and may be adapted to provide an adaptable flow resistance in gas carrying line 3 . In other words, the quantity of a gas flowing through gas carrying line 3 may be determined by the position of actuator 2 .
Actuator 2 is connected to an actuating drive 6 , which may be configured as an electromechanical actuating drive, for example. Actuating drive 6 may be triggered by electrical triggering signals to exert an actuating torque or an actuating force on actuator 2 , so that the latter is moved. Actuating drive 6 may be configured as a dc motor, as an electrically commutated motor or as a stepping motor, for example, each of which may be triggered by suitable pulse width-modulated trigger signals. Actuating drive 6 is able to provide the actuating torque via the trigger signals, which may be generated by a driver circuit using one or more H bridge circuits.
The actual position of actuator 2 may be detected by a position sensor 4 connected to actuator 2 and may be provided as actual position indication y. Additional state variables of position transducer system 1 , such as a motor current, which is picked up for providing an actuating torque by actuating drive 6 and the like, may be detected with the aid of an additional sensor 12 connected to actuating drive 6 .
Position transducer system 1 is generally exposed to environmental influences and aging in the area of application. Furthermore, the individual components are subject to tolerances during their manufacture. This may result in the system response of position transducer system 1 possibly deviating from a desired nominal system response. Since a controller for position transducer system 1 must usually be adapted to the nominal system response of a position transducer, this may result in maladjustments, which has a negative effect on the quality of the control process.
FIG. 2 schematically shows essentially a control system 13 for controlling actuating drive 6 of position transducer system 1 . A control device 5 is provided, which receives actual position indication y from position sensor 4 and also includes a module 14 , which provides a setpoint position indication r and additional measured or modeled state variables z to control device 5 . For example, one of the provided state variables z may correspond to battery voltage U bat .
In addition, control device 5 receives measured variables x such as the motor current or the like from position transducer system 1 , for example. Control device 5 generates a manipulated variable u from the obtained information and uses it to trigger actuating drive 6 of position transducer system 1 . Manipulated variable u may be, for example, a pulse duty factor for a pulse width-modulated triggering of a driver circuit for actuating drive 6 , which corresponds to the effective level of the voltage applied to actuating drive 6 . The pulse duty factor is able to determine the ratio of a period of time during which a motor current flows through actuating drive 6 to a cycle duration, the cycle duration corresponding to a period of cyclic triggering of actuating drive 6 .
FIG. 3 shows the structure of control device 5 in detail. Control device 5 includes a prefilter and pilot control block 7 , a parameter identification block 9 and a control unit 8 . Parameter identification block 9 calculates regularly, cyclically or at a predefined point in time model parameters Θ of a computation model of position transducer system 1 , i.e., the model parameters of the computation model of position transducer system 1 may be determined during active control. Model parameters Θ of the computation model of position transducer system 1 are ascertained on the basis of manipulated variable u, actual position indication y of actuator 2 and optionally on the basis of states x and z, which are additionally measured and modeled, such as motor current and/or battery voltage U bat and the like, for example. Parameter identification block 9 is able to ascertain model parameters Θ, for example, by using a recursive method (a recursive least square method or a gradient method).
Filtering of setpoint position indication r into a filtered setpoint position indication r p and generating a pilot control variable u r for manipulated variable u are carried out in prefilter and pilot control block 7 . For this purpose, instantaneous determined parameters Θ of a computation model of position transducer system 1 as well as a few additional measured and modeled states x and z and instantaneous actual position indication y of actuator 2 are needed.
Manipulated variable u for actuating drive 6 is generated in control unit 8 with the aid of pilot control variable u r , filtered setpoint position r p , instantaneous actual position indication y of actuator 2 , repeatedly determined model parameters Θ of a computation model G of position transducer system 1 and optionally a few additional measured and modeled state variables z of the system as a whole and one or more state variables x of position transducer system 1 .
FIG. 4 shows in detail the structure of prefilter and pilot control block 7 . Prefilter and pilot control block 7 has a prefilter block 10 and a pilot control block 11 . Prefilter block 10 acts as a state-variable filter. The order of prefilter 10 corresponds to the order n of the system. A prefilter of the third order (n=3) is selected in this exemplary embodiment. The order of prefilter 10 may differ from this in other exemplary embodiments.
Prefilter block 10 is implemented in such a way that it low-pass filters the setpoint position indication r to provide filtered setpoint position indication r p and to provide a vector d k r p having k of 1 to n in the case of filtered setpoint position indication r p . Vector d k r p is a vector of the derivations from r p to the order n. For n=3, vector d k r p is composed of d 1 r p as the first derivation from r p over time, d 2 r p as the second derivation from r p over time and d 3 r p as the third derivation from r p over time. Prefilter block 10 uses pilot control variable u r and a few other measured and modeled state variables z of the system as a whole such as, for example, battery voltage U bat and other variables to calculate its output variable anew, when pilot control variable u r reaches its voltage limit, which is a function of the additionally measured and modeled state variables z. Prefilter block 10 implements primarily the low-pass function, which is necessary to permit usable derivations since setpoint position indication r p may contain noise.
Pilot control block 11 is configured as a flatness-based pilot control block. Pilot control block 11 carries out a calculation of an inverse function G −1 of computation model G of position transducer system 1 with the aid of instantaneously determined model parameters Θ and derivations d k r p of filtered setpoint position indication r p . Pilot control block 11 may also take into account the additionally measured and modeled state variables x and z to carry out an adaptation.
FIG. 5 shows the structure of control unit 8 . Control unit 8 includes a differential block 17 , an adaptive filter 15 and a control block 16 . Differential block 17 ascertains the system deviation as a difference E between filtered setpoint position indication r p and instantaneous actual position indication y of actuator 2 : ε=r p −y.
Adaptive filter 15 carries out an adaptation of system deviation E to adapted system deviation ε a in such a way that control block 16 always controls a similar system. Linear computation model G of actuator 2 may correspond to a transfer function H of the order n, which is characterized by instantaneously determined model parameters Θ.
Control block 16 corresponds to a transfer function C, which may be implemented as a discrete recursive equation with the aid of Tustin's method for discretization. Depending on the type of control, at least one of control parameters K p , K i , K d may be implemented for the proportional component, the integration component and the differential component, which are provided as constant nonadaptable control parameters. Fundamentally any type of control is conceivable here.
As an alternative, it may be provided that control block 16 is configured using variable control parameters instead of fixed control parameters K p , K i , K d , so that the adaptation of adaptive filter 15 may also be carried out in control block 16 .
Transfer function C is created for a computation model G nom of a nominal position transducer system 1 to obtain a desired response β nom =C·G nom of the open control loop. Computation model G nom of nominal position transducer system 1 is based on nominal parameters, so that computation model G nom maps nominal position transducer system 1 . Computation model G nom of nominal position transducer system 1 may take into account only linear components, so the computation model is generally in the following form for n=3:
G nom ( s ) = 1 a nom s 3 + b nom s 2 + c nom s 1 + d nom
where a nom , b nom , c nom , d nom correspond to model parameters Θ nom for the nominal position transducer system 1 .
In addition, computation model G of position transducer system 1 to be controlled may take only linear components into account, so the computation model is generally in the following form for n=3:
G ( s ) = 1 as 3 + bs 2 + cs 1 + d
where a, b, c, d correspond to model parameters Θ for position transducer system 1 to be controlled.
Adaptive filter 15 carries out the transfer function
H = G nom G = as 3 + bs 2 + cs 1 + d a nom s 3 + b nom s 2 + c nom s 1 + d nom
using system deviation c in such a way that response β=H˜C·G of the open control loop always reverts to desired response β nom =C·G nom of the open control loop. Transfer function H of adaptive filter 15 is implemented as a discrete recursive equation with the aid of Tustin's method for discretization. An adapted system deviation ε a results from this discrete recursive equation.
Control block 16 calculates manipulated variable u as a function of the discrete recursive equation of the implemented transfer function C of the controller and as a function of pilot control variable u r . Control block 16 includes an anti-integration saturation mechanism to calculate its outputs and internal states anew when the absolute value of manipulated variable u exceeds the voltage limits which are a function of additionally measured and modeled state variables z such as battery voltage U bat and the like.
FIG. 6 shows a function diagram to illustrate the function carried out in prefilter and pilot control block 7 . Prefilter 10 carries out the following transfer function:
P
(
s
)
=
1
(
1
+
τ
p
s
)
n
This transfer function may be discretized with the aid of the Tustin transformation. The resulting differential equation yields relationships among the instantaneous values of filtered setpoint position indication r p , its derivations according to vector d k r p and their preceding values:
{ r p ( k ), d 1 r p ( k ), . . . , d n r p ( k )}= f ( r p ( k− 1), d 1 r p ( k− 1), . . . , d n r p ( k− 1))
Although the k−1 th values are used in Tustin's method proposed above, it is fundamentally possible to use the k−i th values with iε{1 . . . n}.
In FIG. 6 , the preceding values of filtered setpoint position indication r p and its derivations d k r p
{ r p ( k− 1), d 1 r p ( k− 1), . . . , d n r p ( k− 1)}
are initialized in an initializing block 18 using predefined initialization values. The initialization values are provided with the aid of a vector of initialization variables p mem0 . The function of initialization block 18 is called up only once, namely at the start of the control process, to initialize a value vector of preceding values p mem . The preceding values {r p (k−1), d 1 r p (k−1), . . . , d n r p (k−1)} are subsequently copied into value vector p mem after their recalculation.
The variables required by the prefilter and pilot control block 7 for the calculation are input into read-in block 19 , in particular the measured and modeled state variables x (of the position transducer system) and z (of the overall system), the value vector p mem for the preceding values of r p and d k r p , the setpoint position indication r and the parameter vector of the instantaneously valid parameters Θ.
The differential equation
{ r p ( k ), d 1 r p ( k ), . . . , d n r p ( k )}= f ( r p ( k− 1), d 1 r p ( k− 1), . . . , d n r p ( k− 1))
is calculated in calculation block 20 to calculate the filtered setpoint position indication r p and its derivations d k r p .
In a compensation block 21 , compensation of the nonlinearities of position transducer system 1 and the calculation of an unlimited pilot control variable u r _ unlim are carried out prior to their limitation to pilot control variable u r . The nonlinearities to be compensated correspond to the emergency operation, for example, and/or the frictional behavior of actuator 2 . The compensation of compensation block 21 ensures through a pilot control that nonlinearities do not have a negative effect on the control process. For example, FIG. 8 shows a diagram representing the behavior and position y of actuator 2 at various trigger voltages U. In the diagram in FIG. 8 , U max corresponds to the highest possible voltage, U min corresponds to the lowest possible voltage, y max corresponds to the maximum position, U LHmin determines the voltage at a position y LHmin and U LHmax determines the voltage at a position y LHmax , the spring characteristic curve having an increased slope between U LHmin and U LHmax .
At a trigger voltage of 0 V, which may occur in the event of failure of the trigger system, for example, actuator 2 should assume a position y 0 which allows a certain gas mass flow rate through position transducer system 1 to ensure the emergency operation. In the area around position y 0 of actuator 2 , a return spring acts on actuator 2 with an increased spring constant. The increased spring constant in particular acts on actuator 2 in a range y LHmin <y 0 <y LHmax whereas a lower spring constant acts on actuator 2 in the outside areas.
Unlimited pilot control variable U r _ unlim is compared with battery voltage U bat in limitation block 22 . If the absolute value of battery voltage U bat is not exceeded, then pilot control variable u r is set to the value of unlimited pilot control variable u r _ unlim . If the absolute value of battery voltage U bat is exceeded, unlimited pilot control variable u r _ unlim is limited to the value of battery voltage U bat and filtered setpoint position indication r p and its derivations d k r p {r p (k−1), d 1 r p (k−1), . . . , d n r p (k−1)} are calculated anew, taking into account the fact that pilot control variable u r is limited to the value of battery voltage U bat .
Pilot control variable u r and filtered setpoint position indication r p are transferred to control block 8 in a transfer block 23 .
The instantaneous values of vector p mem are stored in a memory block 24 to be available for the next calculation by prefilter and pilot control block 7 .
FIG. 7 shows a flow chart to illustrate a method for generating manipulated variable u in control block 16 . Control block 16 carries out a calculation according to a predefined transfer function C, which may correspond to that of a PIDT1 control, for example. In this case, the carried out transfer function corresponds to:
C ( s ) = K p + K i s + K d s 1 + τ d s
including constant control parameters K p , K i , K d for the proportional component, the integration component, the differential component of the control and time constant τ d . The control parameters remain unchanged even during adaptation of the control process and constitute the optimal control parameters, i.e., those ascertained previously with respect to a reference position transducer system.
This transfer function C may be discretized with the aid of Tustin's transformation. Tustin's discretization method has the advantage that the resulting differential equation includes only simple computation operations, which may be executed in real time even on a low-power control unit. The resulting differential equations define a relationship between the instantaneous values of adapted system deviation ε a and their preceding values. In addition, manipulated variable u corresponds to a function of the results of the differential equations and of pilot control variable u r :
u ( k )= g 1 ( u r ( k ),ε u ( k ),ε a ( k− 1))
In FIG. 7 , the preceding value of adapted system deviation ε a , ε a (k−1) is initialized in initialization block 25 using the predefined initialization value. The initialization value is provided with the aid of a value vector of initialization variables c mem0 . The function of initialization block 25 is called up only once, namely at the start of the control process, to initialize a value vector of preceding values c mem . Preceding value ε α (k−1) is subsequently copied into value vector c mem after its recalculation.
In a provision block 26 , the variables required for the calculation in control block 16 are input, i.e., measured and modeled state variables z, value vector c mem of the preceding values, adaptive system deviation ε a and pilot control variable u r .
The differential equation
u unlim ( k )= g 2 ( u r ( k ),ε a ( k ),ε a ( k− 1))
is calculated in a calculation block 27 to ascertain unlimited manipulated variable u unlim .
In limitation block 28 , the anti-integration saturation function is taken into account to carry out a new calculation when unlimited manipulated variable u unlim reaches a predefined voltage limit. The predefined voltage limit may be calculated according to a predefined function of the additionally measured and modeled state variables z such as battery voltage U bat and the like, for example. A traditional anti-integration saturation function involves freezing the integration part of the control, so that the integration part does not diverge. Unlimited manipulated variable u unlim may also be compared to battery voltage U bat . If battery voltage U bat is not exceeded, manipulated variable u is set at the value of unlimited manipulated variable u unlim . If battery voltage U bat is exceeded, manipulated variable u is limited to the value of battery voltage U bat and the integration part of the control is frozen.
In a transfer block 29 , manipulated variable u is transferred to actuating drive 6 of position transducer system 1 . As described above, the manipulated variable may correspond to a pulse duty factor T.
In a memory block 30 , the instantaneous values of value vectors c mem are stored for the next calculation by control block 16 .
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A method for operating a controller for a position transducer system, of a throttle valve position transducer in an engine system having an internal combustion engine, the control being performed to obtain a manipulated variable for triggering an actuating drive of the position transducer system, the control being performed by initially applying a transfer function to a system deviation to obtain an adapted system deviation and subsequently applying a transfer function to the adapted system deviation to obtain the manipulated variable, the transfer function being a function which indicates a deviation of a model of a nominal position transducer system having predefined nominal parameters from the model of the position transducer system to be controlled, an adaptation of the control process being performed by adapting the transfer function, in that the parameters of the model of the position transducer system to be controlled are adapted, in particular in real time.
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CROSS REFERENCE TO RELATED APPLICATION
This application claims the priority of German Application No. P 40 36 705.3 filed Nov. 17, 1990, which is incorporated herein by reference
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for improving the crushing action of demolition tools, which include a carrier body on which two cooperating jaws, shears or tongs (hereafter collectively also referred to as "jaws") are mounted for engaging, from opposite sides, the matter to be crushed. At least one of the jaws is driven and is thus movable relative to the carrier body.
The drive unit which operates the demolition jaw or jaws and which also generates the necessary closing force during the crushing process may have any desired construction. In present-day demolition tools the drive unit is usually composed of one or more cylinder units with which one jaw is operated or both jaws are driven simultaneously.
German Patent 3,342,305 to which corresponds U.S. Pat. No. 4,512,524 discloses a concrete crusher which includes two jaws that are movably supported by a carrier body and which are each driven by means of a hydraulic cylinder unit.
In contrast thereto, the demolition shears disclosed in European Patent Application 218,899 includes only one movable shearing arm and a drive unit composed of one cylinder unit; the second shearing arm is immovably fastened to the carrier body.
Demolition tools of the type under discussion (demolition jaws or demolition shears) represent in many cases, particularly in the demolition and reconstruction of buildings, an effective alternative to a hydraulic/pneumatic percussion mechanism, a steel ball or explosives. The discussed demolition tools are advantageous in that they operate with low noise and are capable of crushing metal reinforcements and separating--for the purpose of reprocessing/recycling--the different construction materials that are encountered during the crushing process.
The demolition tools according to the prior art are similar insofar as they each generate a continuously active closing force. In crushing concrete or the like, with or without metal reinforcements, in certain work situations the breaking and cutting force exerted by the demolition tool does not produce the desired result. Consequently, frequent changes of position, readjustments and restarting of the demolition tool are required which may lead to a reduction of efficiency and output.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved method of enhancing the crushing action of demolition tools and also, to provide an improved demolition tool suitable for implementing the method for producing a better crushing effect and an improved economy of operation as compared to prior art constructions.
This object and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, the method of crushing material between cooperating jaws of a crushing jaw assembly of a demolition tool includes the steps of applying a closing force to at least on of the jaws for urging the jaws toward one another; and imparting a vibratory motion to at least one of the jaws while the closing force is applied.
It is thus a basic concept of the invention to at least temporarily superpose vibratory movements on the closing force exerted by the jaws. The pulsating stresses imparted on the material to be crushed in the jaw opening (jaw mouth) may increase the crushing and demolition performance to a considerable degree.
According to an advantageous feature of the invention, during the crushing process at least one of the jaws is directly caused to vibrate; in the simplest case, this may be brought about by means of a vibration generator which directly imparts corresponding movements to the respective jaw or jaws. According to a further feature of the invention, at least one of the jaws is caused to vibrate indirectly, for example, by way of a device attached thereto.
For purposes of improved economy and noise reduction, the vibratory movements are initiated only after the closing force acting on the jaws has risen to a predetermined, adjustable minimum value. Only after the expected crushing effect can no longer be realized during normal operation, is the demolition process continued with superposed vibrations. If this results in the desired work progress, the closing force temporarily drops to below the set minimum value so that the vibratory movements are interrupted. This procedure may be repeated several times during one work cycle, that is, until the jaw opening of the demolition tool is closed.
To prevent the superposition of vibrations from being maintained over an unnecessarily long period of time without achieving any work progress, the vibratory movements are, according to a further feature of the invention, interrupted after each predetermined, adjustable time period.
In order to exclude undesirable stresses on the demolition tool when the jaws are in contact with one another, the method provides that the generation of vibratory movements is discontinued as soon as the jaws approach a predetermined end position in the course of their closing movement.
The tool according to the invention includes a vibration generator which may be energized during operation of the drive unit and which affects at least one movable jaw so as to initiate vibratory movements that act on the material to be crushed.
According to a preferred embodiment, at least one of the two jaws can be connected to be driven by the vibration generator. As a result, one jaw or both jaws directly perform corresponding movements with respect to the carrier body under the influence of the vibration generator.
Preferably, the vibration generator acts on the drive unit of the demolition tool so that the drive unit itself generates the vibratory movements for the respective jaw.
According to another preferred embodiment, the vibratory movements are initiated by means of at least one striking mechanism that is mounted in the jaw or jaws. The striking mechanism impacts directly the material to be crushed in the jaw opening and thus also indirectly causes the jaws to vibrate.
In the simplest case, the percussion mechanisms are composed of a cylinder unit including a striking piston displaceable by a pressure medium against a resetting force. The striking mechanisms may include a reversal control for the movement of the striking piston, similarly to hydraulic hammers.
According to a further embodiment of the invention, the vibratory movements may be effected by a pressure medium exposed to a pulse generator. The pulse generator may be a conventional rotary valve pulse generator which supplies a pulsating stream of pressure medium. The stream may be employed to charge the drive unit (composed of one or several cylinder units) and/or at least one striking mechanism.
According to still another embodiment of the invention, the vibratory movements are effected by means of at least one unbalance generator which is in engagement with a jaw. Particularly in embodiments that have two movable jaws, the latter are each equipped with an unbalance generator, preferably in such a way that the forces exerted by the unbalance generators are directed opposite to one another with respect to the material to be crushed.
The demolition tool may be so structured according to the invention that the material to be crushed is subjected to vibratory action that is generated by the drive unit as well as by at least one striking mechanism or an unbalance generator. Preferably, the vibratory movements are initiated by actuation of a switching unit only after a characteristic value--which constitutes a measure for the stress during the demolition process--has risen to a predetermined, adjustable minimum value. If the demolition tool is operated hydraulically, the operating pressure for the drive unit is particularly applicable as a characteristic value. The longest possible time period for the vibratory movements can be adjusted by means of a timing member which energizes the vibration generator as soon as the characteristic value reaches the minimum value.
In a preferred embodiment of the invention, an energizing valve is provided which is controlled by the operating pressure of the drive unit. A timing member connected to the valve output effects an eventual energization of the pulse generator. The energy supply for the pulse generator can also be interrupted by the timing member independently of the position of the energizing valve. If thus the operating pressure, after it has reached a predetermined minimum value, does not drop below this minimum value, the pulse generator is nevertheless de-energized after the expiration of a predetermined time period.
For safety reasons, at least one driven jaw has an associated limit switch by means of which the vibration generator is de-energized when, in the course of the closing movement, the jaw approaches a predetermined end position. This arrangement prevents the vibratory movements from being maintained or started when the characteristic value reaches the predetermined minimum value at a time when, upon the completion of the closing movement, the jaws are in engagement with one another.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 a schematic perspective view of a hydraulic excavator having a crushing jaw assembly that incorporates the invention.
FIG. 2 is a side elevational view of crushing jaws of the FIG. 1 and a circuit diagram of a preferred embodiment of the invention.
FIG. 3 is a fragmentary side elevational view of crushing jaws, shown partially in section, and a circuit diagram of another preferred embodiment of the invention.
FIG. 4 is a sectional view along line IV--IV of FIG. 3.
FIG. 5 partial view of a crushing jaw to which an unbalance is attached in accordance with a further preferred embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a crushing jaw assembly 1 in a hydraulic excavator 4 for the crushing/demolition of a concrete slab 3 firmly held in the ground 2.
In a known manner, the crushing jaw assembly includes two driven jaws 5 and 6 movably held in a carrier body 7. The carrier body 7 is rotatably fastened by a coupling plate 8 to a connecting bracket 9 which, in turn, is pivotally mounted on an excavator arm 10, essentially composed of a front pivot arm 11 and a rear carrier arm 12. The latter is pivotal with respect to a platform 13 of the hydraulic excavator which accommodates, among others, a hydraulic unit 14 serving as the energy source for operating the crushing jaw assembly 1.
Turning to FIG. 2, the drive unit for operating the two jaws 5 and 6 includes two cylinder units 15 and 16 which are articulated by way of their cylinder housings 15a, 16a and their piston rods 15b, 16b to the carrier body 7 and the respective jaw 5 and 6. The jaws 5 and 6 are supported at the carrier body 7 by respective rotary bearings 5a and 6a, at a distance from the articulation of piston rods 15b, 16b and define an adjustable jaw opening 17 of the demolition tool into which the concrete slab 3 to be crushed projects during the demolition process.
Each jaw 5 and 6 has two teeth 5b, 5c and 6b, 6c which extend along the assembly axis 1a and project theretoward. The jaws 5 and 6, together with the respective teeth 5b, 5c and 6b, 6c, apply a pressing force on the slab 3 by virtue of a closing force exerted by cylinder units 15, 16. The arrangement and configuration of the major components of the crushing jaw assembly 1 are essentially symmetrical with respect to the longitudinal axis 1a.
In the vicinity of the rotary bearing 6a, the jaw 6 carries an abutment lug 18 which is arranged in such a manner with respect to a limit switch 19 (formed as a two-position, "on-off" valve) fastened to carrier body 7 that, by contacting a switch sensor 19b, it depresses the limit switch 19 against the force of a reset spring 19a from the "off" (closed) position into the "on" (open) position as soon as the two jaws 5 and 6 approach in the course of the closing movement, a predetermined end position in which the jaws 5, 6 are close to a mutually contacting position.
The start-up, reversal or de-energization of the crushing jaw assembly 1 is effected by a 3-position, 2-way valve 20 which has an input connected with a hydraulic source 21 and an output connected to a pressureless return conduit 22 including a return filter 23. The outlet side of the valve 20 is connected, through the intermediary of a pressure controlled direction control valve 24 and a conduit 25, with the piston rod-extension inlets 15c, 16c of the two cylinder units 15, 16 and via a conduit 26 with piston rod-retraction inlets 15d, 16d.
As long as direction control valve 24 is in the position shown in FIG. 2, a displacement of the valve 20 to the right causes the inlets 15c, 16c to be charged with pressure through conduit 25 and the inlets 15d, 16d to be pressure-relieved through conduit 26. As a result, a closing force is exerted by way of piston rods 15b, 16b on crushing jaws 5, 6 which thus move toward one another against the resisting force of the concrete slab 3. A displacement of the valve 20 to the left causes the inlets 15d, 16d to be charged with pressure through conduit 26 and thus the jaws 5, 6 are moved away from one another so as to perform an opening movement which enlarges jaw opening 17.
Conduit 25 has a branch conduit 25a which includes a vibration actuator valve 27 whose position can be affected--against an adjustable biasing force--by a control conduit 27a that opens into conduit branch 25a. In the flow-through position (not shown) of the vibration actuator valve 27, the operating pressure present in conduits 25, 25a is applied to the control inlet 24a of direction control valve 24, a pressure-controlled timing member 28 and a conduit 29 which may be connected by the valve 19 to a relief (return) conduit 30. As long as the valve 19 is in the illustrated blocking ("off") position, no communication exists between return conduit 30 and conduit 29. Thus, the latter--similarly to timing member 28 and control inlet 24a--may be charged with the operating pressure. The vibration actuator valve 27 is set in such a way that it switches from the blocking position to the flow-through position only after the operating pressure in conduits 25, 25a has reached a set minimum value which, in turn, is a measure for the closing force exerted by cylinder units 15, 16 on jaws 5, 6.
The conduit 25 is connected to a pulsating fluid conduit 32 with the intermediary of a check valve 31. The conduit 32 is chargeable with a pulsating pressure by a rotary-valve pulse generator 33 which is driven by a hydraulic motor 34. The pulse generator 33 is connected with a second outlet of the valve 24 by way of an intake conduit 35 also communicating with a pressure reservoir 36. Through the intermediary of a pressure controlled shutoff valve 37, the intake conduit 35 communicates with a driving conduit 38 for a hydraulic motor 34, whose return conduit 39 is, in turn, connected to the relief conduit (return conduit) 22.
A pressure switch 28 actuates, through a switching conduit 40, a timer 41 which is connected with the control inlet 37a of the shutoff valve 37 and with an outlet 42.
As soon as timer 41 is pressurized by means of the switch 28, the communication between conduits 40 and 42 is interrupted and simultaneously a counting process is started, whose duration is adjustable. As long as the counting is in progress, the shutoff valve 37 which is pressurized at the inlet 37a, is in its non-illustrated open (flow-through) position so that if the valve 24 is in an appropriate position, the hydraulic motor 34 is supplied with driving energy through the conduit 38. Upon completion of the counting process, the timer 41 opens the relief outlet 42, whereby the pressure drops at the inlet 37a and thus the shutoff valve 37 switches to the illustrated closed (blocking) position. Since the energy supply to the hydraulic motor 34 is interrupted, the pulse generator 33 that has been active during the time period in question is turned off. The displacement of the vibration actuator valve 27 into the non-illustrated flow-through position causes the valve 24 to switch into its second position (not shown) in which communication is established between conduits 25 and 38, among others, through the shutoff valve 37. Pressure reservoir 36 serves to compensate the pressure fluctuations which were intentionally generated during operation of the pulse generator 33 and which, as fed-back pressure fluctuations, are undesirable outside of the region of cylinder units 15, 16.
Thus, the pressure switch 28 and timer 41 constitute a timing member which, at the end of an adjustable, predetermined time period, automatically interrupts and prevents the generation of further pulsating pressure fluctuations independently of the position of the vibration actuator valve 27.
In the description which follows, the operation of the embodiment of FIG. 2 will be set forth.
After start-up of the crushing jaw assembly 1 by displacement of the valve 20 to the right (that is, communication is established between conduit 25 and pump 21 and between conduit 26 and sump 23a), inlets 15c, 16c are charged with pressure to initiate the normal closing process which results in a closing force exerted by jaws 5, 6 that serve to crush/demolish the concrete slab 3. If the action of the jaws does not result in the desired work progress, the operating pressure in conduits 25, 25a and 27a increases so that the vibration actuator valve 27, which was initially in the shutoff (blocking) position, eventually switches into the vibration-actuating position and thus moves the valve 24 into its non-illustrated second operating position (that is, to the right) and, under the influence of switches 28 and 41, moves the shutoff valve 37 into the flow-through (open) position. These operative steps cause the hydraulic motor 34, which is supplied with energy through conduits 25, 38, to drive the pulse generator 33 so as to generate intentional pressure fluctuations in conduits 32, 25 and in cylinder units 15, 16, as a result of which jaws 5, 6 are directly caused to vibrate. The activation of hydraulic motor 34 and pulse generator 33 thus leads to vibratory movements being temporarily superposed on the closing force to improve the demolition effect of the jaws.
The superposition of vibrations lasts as long as the vibration actuator valve 27 is, as a function of the operating pressure in conduits 25, 25a and 27a, in the actuating position. In any event, the duration of such actuating position is limited in time by the time period predetermined by timer 41. At the end of the time period the outlet 42 is opened and thus, by returning the shutoff valve 37 into the illustrated blocking position, the generator 33 is deenergized.
If the generation of vibratory movements within a predetermined period of time does not result in work progress, the operator is able to open the jaws 5, 6 of the crushing jaw assembly 1 by switching the valve 20 and, for example, moving the assembly 1 to another position.
Undesirable stress on the components of the crushing jaw assembly 1 is prevented by moving the limit switch 19, toward the end of the closing movement, into the open position (not shown) by means of the abutment lug 18, thus connecting the conduit 29 to the pressureless return conduit 30. It is thus impossible to charge the valve 24 and the pressure switch 28 with the pressure required to initiate the vibratory movements even if the vibration actuator valve 27, due to a rise in the operating pressure, assumes its actuating position.
It is an advantage of the embodiment of FIG. 2 that the jaws 5, 6 are temporarily directly caused to vibrate themselves under the influence of cylinder units 15, 16 and considerable additional pulsating forces are generated which support the demolition process. This, however, requires that the vibration generator (hydraulic motor 34 and rotary valve pulse generator 33) be designed accordingly.
Turning now to FIGS. 3 and 4, the demolition jaw assembly 1' structurally differs from the jaw assembly 1 in that the clamping jaws 5' and 6' each have but a single tooth (such as 6b') which projects toward the longitudinal axis 1a. Each clamping jaw is provided with two striking mechanisms 43 in the region of its tooth. The striking mechanisms--when seen transversely to the plane of FIG. 3--lie spaced from one another in the region of the tooth, as shown in FIG. 4. Each striking mechanism includes a piston rod 43a and a piston 43b that can be extended relative to the jaw in which it is mounted and can be displaced outwardly against the force of a resetting spring 45 by pressure pulsations supplied by a pulse conduit 44, that is in the direction toward the concrete slab 3 to be crushed.
In contrast to the embodiment according to FIG. 2, the rod-extension inlets of the cylinder units--for example the rod-extension inlet 16c of cylinder unit 16--are connected by a conduit branch 25a and a conduit 25 with the valve 20 described in connection with the FIG. 2 embodiment. As concerns the cylinder units, the valve 20 thus has only the function of causing the cylinder units to perform a closing or opening movement.
The vibration actuator valve 27 also connected with conduit branch 25a affects, through control input 46a, the position of a spring-biased shutoff valve 46 which, in its open position, connects conduit 25 with the conduit 38 for hydraulic motor 34, with the intake conduit 35 for the rotary valve pulse generator 33 and with the pressure reservoir 36.
The striking mechanism 4 is oscillated by the pulse generator 33 through the pressure conduit 44.
In the description which follows, the operation of the FIG. 3 embodiment will be set forth.
Actuation of the valve 20 by displacement to the right (as viewed in FIG. 3) causes the cylinder units to be charged with pressure through conduits 25, 25a so that their respective piston is driven outwardly. As a result, the teeth of the jaws 5', 6' contact the concrete slab 3 to be crushed and exert thereon the closing force generated by the cylinder units. The striking mechanisms 43 are not in operation at this time, since the shutoff valve 46 is in the blocking position shown in FIG. 3. Consequently, the rotary valve pulse generator 33 is not active and the pulse conduit 44 is not charged with pressure. As urged by the reset springs 45, the piston rods 43 and the pistons 43b are in their rest position shown in FIG. 4.
If the normal pressurizing of the cylinder units does not achieve the desired crushing results, the operating pressure in conduits 25, 25a and 27a increases. As soon as a minimum pressure value determined by the vibration actuator valve 27 is reached, the latter switches into the non-illustrated actuating position and moves, by applying pressure to control inlet 46a, the shutoff valve 46 into the open position (not shown) to thus energize the hydraulic motor 34 which, in turn, drives the pulse generator 33. The latter applies a fluctuating fluid pressure to the striking mechanisms 43 by way of pulse conduit 44 in such a way that their components 43a and 43b perform back and forth movements. As long as the valve 27 is in the actuating position, vibratory movements that act on concrete slab 3 are thus additionally superposed on the closing force exerted by the jaws 5' and 6'. Since the latter absorb the pulsating forces emanating from the striking mechanisms 43, they are likewise caused to vibrate indirectly by way of these pulsating forces. The operative inclusion of the pulse generator 33 as determined by the operating conditions achieves results which would otherwise not be possible without changing the position of the demolition jaws.
The FIG. 3 embodiment, similarly to the embodiment according to FIG. 2, can be advantageously modified in that the vibration actuator valve 27 is connected with the shutoff valve 46 through the intermediary of pressure switch 28, switching conduit 40, timer 41 and outlet 42. In such a modification, shutoff valve 46 is switched automatically into the illustrated closed position at the end of an adjustable, predetermined period of time, independently of the position of the valve 27, thus interrupting the energy supply to hydraulic motor 34.
In the embodiment according to FIG. 5, the vibratory movements of the crushing jaws (of which only jaw 6" is shown) are imparted by unbalance generators 47 attached to the respective jaws. These unbalance generators are arranged and configured in such a manner that the forces they exert are always directed opposite to one another with respect to the concrete slab 3 to be crushed.
It is within the scope of the invention to so design a crushing jaw assembly and its power supply that the several types of vibration explained in connection with FIGS. 2-5 may be simultaneously, or separately or sequentially superposed on the closing force. If thus, for example, the vibratory movements of the jaws do not yet produce the desired work progress, such may possibly by realized by operatively including the striking mechanisms and/or the unbalance generators.
The method proposed by the present invention can also be performed manually. Preferably, for such an operation a characteristic value is determined which constitutes a measure for the stress on the crushing jaws during the demolition process and this value is displayed. An operator can then initiate the superposition of vibrations on the basis of the predetermined value and, if it does not result in the desired work progress, the operator may switch off the vibratory forces after a period of time that appears suitable.
It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.
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A method of crushing material between cooperating jaws of a crushing jaw assembly of a demolition tool includes the steps of applying a closing force to at least one of the jaws for urging the jaws toward one another; and imparting a vibratory motion to at least one of the jaws while the closing force is applied.
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FIELD OF THE INVENTION
The present subject matter relates generally to washing machine appliances and more particularly to washing machine appliances having a system for adding supplemental wash liquid.
BACKGROUND OF THE INVENTION
Washing machine appliances generally include a tub for containing water or wash liquid, e.g., water and detergent, bleach, and/or other wash additives. A basket is rotatably mounted within the tub and defines a wash chamber for receipt of articles for washing. During normal operation of such washing machine appliances, the wash liquid is directed into the tub and onto articles within the wash chamber of the basket. The basket or an agitation element can rotate at various speeds to agitate articles within the wash chamber, to wring wash fluid from articles within the wash chamber, etc.
During operation of certain washing machine appliances, a volume of wash liquid is directed into the tub in order to wash and/or rinse articles within the wash chamber. One or more fluid additives may be added to the wash liquid to enhance the cleaning or other properties of the wash liquid. The fluid additives may be in powder or concentrated liquid form, and are generally added to a dispenser box of the washing machine appliance by, e.g., a user of the washing machine appliance. The dispenser box may contain various chambers for containing different additives, e.g., wash detergent and softener. Water may be directed into the chambers of the dispenser box through a plurality of water inlet valves to mix with the additives and the resulting wash liquid is then dispensed into the wash chamber.
The volume of water or wash liquid needed may vary depending upon a variety of factors. For example, large loads can require a large volume of water relative to small loads that can require a small volume of water. A user may wish to have additional wash liquid dispensed in order to perform a specific task, e.g., prewash an article of clothing or add additional liquid to accommodate an extra large load. The ability to adjust the amount of water or wash liquid dispensed is a generally commercially desirable feature and increases the user's positive perception of the wash process generally. However, conventional washing machine appliances typically do not have water-on-demand features, and those that do require additional nozzles, hoses, clamps, and other hardware to perform such a function.
Accordingly, a washing machine appliance that provides a user with more control over the water or wash liquid fill amount is desirable. In particular, a dispenser box having a simple, convenient, integrated system for dispensing an additional predetermined amount of wash liquid would be particularly beneficial.
BRIEF DESCRIPTION OF THE INVENTION
The present subject matter provides a washing machine having an integrated water-on-demand feature. More particularly, the present subject matter provides a washing machine appliance that allows a user to adjust the water or wash liquid fill amount of the washing machine appliance using an actuator integrated into or positioned nearby the dispenser box, thereby enabling a simple, convenient, and effective manner of adding wash liquid without requiring a substantial number of additional parts or assembly. Additional aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention.
In one exemplary embodiment, a washing machine appliance defining a vertical, a lateral, and a transverse direction is provided. The washing machine appliance includes a cabinet; a tub positioned within the cabinet; and a wash basket rotatably mounted within the tub, the wash basket defining a wash chamber for receiving articles for washing. The washing machine appliance further includes an additive dispenser positioned within the cabinet and configured to provide wash liquid to the tub. The additive dispenser includes a mixing chamber configured to receive wash additive and a water valve configured to provide a flow of water to the mixing chamber from a water inlet. The additive dispenser further includes a user input button for adding supplemental water to the tub and a controller in operative communication with both the user input button and the water valve. The controller is configured to receive a user input to add a supplemental water fill amount to the tub and open the water valve to provide the tub with the supplemental water fill amount.
In another exemplary embodiment, a dispensing assembly for a washing machine appliance having a tub positioned within a cabinet is provided. The dispensing assembly includes a water valve configured to provide a flow of water from a water inlet and a dispenser box positioned within the cabinet, the dispenser box comprising a mixing chamber configured to receive the flow of water and dispense the flow of water into the tub. The dispensing assembly further includes a user input button and a controller in operative communication with both the user input button and the water valve. The controller is configured to open the water valve to provide the tub with a supplemental water fill amount responsive to the user input button being pressed.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.
FIG. 1 provides a perspective view of a washing machine appliance according to an exemplary embodiment of the present subject matter with a door of the exemplary washing machine appliance shown in a closed position.
FIG. 2 provides a perspective view of the exemplary washing machine appliance of FIG. 1 with the door of the exemplary washing machine appliance shown in an open position.
FIG. 3 provides a front, perspective view of an exemplary dispenser box assembly installed in the exemplary washing machine appliance of FIG. 1 .
FIG. 4 provides a front, perspective view of the exemplary dispenser box assembly of FIG. 3 .
FIG. 5 provides a rear, perspective view of the exemplary dispenser box assembly of FIG. 3 .
FIG. 6 provides a front, perspective view of a front portion of a dispenser box according to another exemplary embodiment of the present subject matter.
DETAILED DESCRIPTION OF THE INVENTION
Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
FIGS. 1 and 2 illustrate an exemplary embodiment of a vertical axis washing machine appliance 100 . In FIG. 1 , a lid or door 130 is shown in a closed position. In FIG. 2 , door 130 is shown in an open position. Washing machine appliance 100 generally defines a vertical direction V, a lateral direction L, and a transverse direction T, each of which is mutually perpendicular, such that an orthogonal coordinate system is generally defined.
While described in the context of a specific embodiment of vertical axis washing machine appliance 100 , using the teachings disclosed herein it will be understood that vertical axis washing machine appliance 100 is provided by way of example only. Other washing machine appliances having different configurations, different appearances, and/or different features may also be utilized with the present subject matter as well, e.g., horizontal axis washing machines.
Washing machine appliance 100 has a cabinet 102 that extends between a top portion 103 and a bottom portion 104 along the vertical direction V. A wash basket 120 ( FIG. 2 ) is rotatably mounted within cabinet 102 . A motor (not shown) is in mechanical communication with wash basket 120 to selectively rotate wash basket 120 (e.g., during an agitation or a rinse cycle of washing machine appliance 100 ). Wash basket 120 is received within a wash tub or wash chamber 121 ( FIG. 2 ) and is configured for receipt of articles for washing. The wash tub 121 holds wash and rinse fluids for agitation in wash basket 120 within wash tub 121 . An agitator or impeller (not shown) extends into wash basket 120 and is also in mechanical communication with the motor. The impeller assists agitation of articles disposed within wash basket 120 during operation of washing machine appliance 100 .
Cabinet 102 of washing machine appliance 100 has a top panel 140 . Top panel 140 defines an opening 105 ( FIG. 2 ) that permits user access to wash basket 120 of wash tub 121 . Door 130 , rotatably mounted to top panel 140 , permits selective access to opening 105 ; in particular, door 130 selectively rotates between the closed position shown in FIG. 1 and the open position shown in FIG. 2 . In the closed position, door 130 inhibits access to wash basket 120 . Conversely, in the open position, a user can access wash basket 120 . A window 136 in door 130 permits viewing of wash basket 120 when door 130 is in the closed position, e.g., during operation of washing machine appliance 100 . Door 130 also includes a handle 132 that, e.g., a user may pull and/or lift when opening and closing door 130 . Further, although door 130 is illustrated as mounted to top panel 140 , alternatively, door 130 may be mounted to cabinet 102 or any other suitable support.
A control panel 110 with at least one input selector 112 ( FIG. 1 ) extends from top panel 140 . Control panel 110 and input selector 112 collectively form a user interface input for operator selection of machine cycles and features. A display 114 of control panel 110 indicates selected features, operation mode, a countdown timer, and/or other items of interest to appliance users regarding operation.
Operation of washing machine appliance 100 is controlled by a controller or processing device 108 ( FIG. 1 ) that is operatively coupled to control panel 110 for user manipulation to select washing machine cycles and features. In response to user manipulation of control panel 110 , controller 108 operates the various components of washing machine appliance 100 to execute selected machine cycles and features.
Controller 108 may include a memory and microprocessor, such as a general or special purpose microprocessor operable to execute programming instructions or micro-control code associated with a cleaning cycle. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor. Alternatively, controller 100 may be constructed without using a microprocessor, e.g., using a combination of discrete analog and/or digital logic circuitry (such as switches, amplifiers, integrators, comparators, flip-flops, AND gates, and the like) to perform control functionality instead of relying upon software. Control panel 110 and other components of washing machine appliance 100 may be in communication with controller 108 via one or more signal lines or shared communication busses.
During operation of washing machine appliance 100 , laundry items are loaded into wash basket 120 through opening 105 , and washing operation is initiated through operator manipulation of input selectors 112 . Wash basket 120 is filled with water and detergent and/or other fluid additives via dispenser box assembly 200 , which will be described in detail below. One or more valves can be controlled by washing machine appliance 100 to provide for filling wash basket 120 to the appropriate level for the amount of articles being washed and/or rinsed. By way of example for a wash mode, once wash basket 120 is properly filled with fluid, the contents of wash basket 120 can be agitated (e.g., with an impeller as discussed previously) for washing of laundry items in wash basket 120 .
After the agitation phase of the wash cycle is completed, wash basket 120 can be drained. Laundry articles can then be rinsed by again adding fluid to wash basket 120 depending on the specifics of the cleaning cycle selected by a user. The impeller may again provide agitation within wash basket 120 . One or more spin cycles also may be used. In particular, a spin cycle may be applied after the wash cycle and/or after the rinse cycle to wring wash fluid from the articles being washed. During a spin cycle, wash basket 120 is rotated at relatively high speeds. After articles disposed in wash basket 120 are cleaned and/or washed, the user can remove the articles from wash basket 120 , e.g., by reaching into wash basket 120 through opening 105 .
Referring now generally to FIGS. 2 through 6 , dispenser box assembly 200 will be described in more detail. Although the discussion below refers to dispenser box assembly 200 , one skilled in the art will appreciate that the features and configurations described may be used for other additive dispensers in other washing machine appliances as well. For example, dispenser box assembly 200 may be positioned on a front of cabinet 102 , may have a different shape or chamber configuration, and may dispense water, detergent, or other additives. Other variations and modifications of the exemplary embodiment described below are possible, and such variations are contemplated as within the scope of the present subject matter.
Dispenser box assembly 200 is a box having a substantially rectangular cross-section that defines a top 202 and a bottom 204 spaced apart along the vertical direction V. Dispenser box assembly 200 also defines a front side 206 and a back side 208 spaced apart along the transverse direction T. As best shown in FIGS. 2 and 3 , dispenser box assembly 200 may be mounted underneath top panel 140 of cabinet 102 such that front side 206 is visible inside opening 105 . More specifically, dispenser box assembly 200 may be mounted to top panel 140 using a plurality of mounting features 210 , which may, for example, be configured to receive mechanical fasteners. One skilled in the art will appreciate that dispenser box assembly 200 may be mounted in other locations and use other mounting means according to alternative exemplary embodiments.
Dispenser box assembly 200 may define a mixing chamber 220 configured to receive one or more additive compartments. For example, according to the illustrated embodiment, mixing chamber 220 may be configured to slidably receive a detergent compartment 222 and a softener compartment 224 . Compartments 222 , 224 are slidably connected to the mixing chamber 220 using slides 226 and are connected to a front panel 228 of dispenser box assembly. In this manner, a user may pull on front panel 228 to slide compartments 222 , 224 along the transverse direction T. Once extended, detergent compartment 222 and softener compartment 224 may be conveniently filled with detergent and softener, respectively. Front panel 228 may be then be pushed back into mixing chamber 220 before a wash cycle begins.
Although the illustrated embodiment shows detergent compartment 222 and softener compartment 224 slidably received in mixing chamber 220 for receiving wash additives, one skilled in the art will appreciate that different configurations are possible in alternative exemplary embodiments. For example, more compartments may be used and the compartments may be accessed by a lid instead of sliding out of mixing chamber 220 . Alternatively, mixing chamber 220 may draw wash additives from a separate storage container such that sliding compartments 222 , 224 are not needed. Other configurations of mixing chamber 220 and compartments 222 , 224 are also possible and within the scope of the present subject matter.
Dispenser box assembly 200 may further include a plurality of valves configured to supply hot and cold water to mixing chamber 220 or directly to wash tub 121 . For example, according to the illustrated embodiment, a plurality of apertures may be defined on top 202 of mixing chamber 220 for receiving water. Each aperture (not shown) may be in fluid communication with a different portion of the mixing chamber. A plurality of valve seats may be positioned over top of each of those apertures to receive a valve that controls the flow of water through each aperture.
For example, a first valve seat 234 may be in fluid communication with a first aperture for providing hot water into detergent compartment 222 . A second valve seat 236 may be in fluid communication with a second aperture for providing cold water into detergent compartment 222 . A third valve seat 238 may be in fluid communication with a third aperture for providing cold water into softener compartment 224 . A fourth valve seat 240 may be in fluid communication with a fourth aperture for providing cold water into mixing chamber 220 or directly into wash tub 121 .
Water inlets may be placed in fluid communication with each of valve seats 234 , 236 , 238 , 240 . More specifically, a hot water inlet 244 may be connected to a hot water supply line (not shown) and a cold water inlet 246 may be connected to a cold water supply line (not shown). According to the illustrated embodiment, each water inlet 244 , 246 may include a threaded male adapter configured for receiving a threaded female adapter from a conventional water supply line. However, any other suitable manner of fluidly connecting a water supply line and water inlets 244 , 246 may be used. For example, each water supply line and water inlets 244 , 246 may have copper fittings that may be sweated together to create a permanent connection.
Notably, hot water inlet 244 is in direct fluid communication with first valve seat 234 . However, because washing machine appliance 100 uses cold water for multiple purposes, cold water inlet is in fluid communication with a cold water manifold 248 . As best shown in FIG. 5 , cold water manifold 248 is a cylindrical pipe that extends along the lateral direction from second valve seat 236 to fourth valve seat 240 . In this manner, cold water manifold 248 places valve seats 236 , 238 , 240 in fluid communication with cold water inlet 246 .
Each of valve seats 234 , 236 , 238 , 240 may be configured to receive a water valve 252 for controlling the flow of water through a corresponding aperture into mixing chamber 220 . Water valve 252 may be, for example, a solenoid valve that is electrically connected to controller 108 . However, any other suitable water valve may be used to control the flow of water. Controller 108 may selectively open and close water valves 252 to allow water to flow from hot water inlet 244 through first valve seat 234 and from cold water manifold 248 through one or more of second valve seat 236 , third valve seat 238 , and fourth valve seat 240 .
Dispenser box assembly 200 may further include one or more nozzles (not shown) for directing wash fluid, such as water and/or a mixture of water and at least one fluid additive, e.g., detergent, fabric softener, and/or bleach into wash tub 121 from dispenser box assembly 200 . For example, when second valve seat 236 is open, water may flow from cold water inlet 246 through cold water manifold 248 and second valve seat 236 into detergent compartment 222 . Water may mix with detergent placed in detergent compartment 222 to create wash liquid to be dispensed into wash tub 121 .
A nozzle (not shown) may be placed on the bottom of detergent compartment 222 or on the bottom of mixing chamber 220 to dispense the wash fluid into wash tub 121 . According to the illustrated embodiment, dispenser box assembly 200 may include four nozzles associated with valves seats 234 , 236 , 238 , 240 , respectively. However, it will be understood that different nozzle configurations may be used in alternative exemplary embodiments. For example, nozzles may be positioned on a bottom of mixing chamber 220 near wash tub 121 or directly on wash tub 121 , but could be positioned in other locations as well.
In some situations, a user may wish to add additional water to wash tub 121 . For example, a user may wish to prewash one or more articles of clothing or may perceive that more water is needed to effectively wash a load. Accordingly, dispenser box assembly 200 may include a system for allowing a user to add water to wash tub 121 on demand, i.e., a water-on-demand feature.
In this regard, dispenser box assembly 200 may include one or more buttons that are configured to control one or more of valves 252 . According to the exemplary embodiment illustrated in FIG. 3 , dispenser box assembly 200 includes a cold water button 260 and a hot water button 262 for controlling valves 252 on first valve seat 234 and fourth valve seat 240 , respectively. However, one skilled in the art will appreciate that additional buttons may be included and the buttons may control different valves 252 or any combination of valves 252 . For example, a third button may be configured to add a “soapy” mixture of hot and/or cold water with a wash additive. In addition, one skilled in the art will appreciate that any of these buttons can be turned on/off independently or together in any combination.
Cold water button 260 and hot water button 262 may be any button or switch suitable for providing an indication to controller 108 that a particular action should be initiated. For example, buttons 260 , 262 may be push button switches, toggle switches, rocker switches, or any other suitable tactile switch, such as capacitive touch buttons. According to the illustrated embodiments, buttons 260 , 262 are momentary switches (sometimes referred to as mom-off-mom switches). In this regard, buttons 260 , 262 are biased switches that return to their unlatched or unpressed state when released, e.g., by spring force.
According to the exemplary embodiment illustrated in FIG. 3 , cold water button 260 and hot water button 262 may be located on front panel 228 of dispenser box assembly 200 . According to an alternative exemplary embodiment illustrated in FIG. 6 , a cold water button 270 and a hot water button 272 may be placed on a bottom surface of top panel 140 adjacent to dispenser box assembly 200 . For example, cold water button 270 may be placed just to the right of mixing chamber 220 and hot water button 272 may be placed just to the left of mixing chamber 220 . In this manner, when a user desires additional water, the user may insert their finger between top panel 140 and wash basket 120 to actuate buttons 270 , 272 .
According to other embodiments, buttons 260 , 262 may be placed in any other suitable location that is easy to access by a user. As illustrated for washing machine appliance 100 , buttons 260 , 262 , 270 , 272 are all positioned in front of control panel 110 . This may be advantageous because washing machine appliance 100 is a vertical axis, top load washing machine that has door 130 that pivots up, thereby blocking access to control panel 110 when door 130 is in the open position. Thus, buttons 260 , 262 , 270 , 272 are preferably located somewhere within wash tub 121 that is easily accessible when door 130 blocks access to control panel 110 .
Notably, buttons 260 , 262 are positioned in a location of washing machine appliance 100 where they may be exposed to very humid, damp conditions, or where they may be directly sprayed with water. Therefore, it is desirable that buttons 260 , 262 operate at a low voltage in order to prevent the possibility of shocking the user. More particularly, buttons 260 , 262 may operate on an isolated Safety Extra Low Voltage (SELV) circuit. In this regard, buttons 260 , 262 may be sealed and rated for direct contact with water. Buttons 260 , 262 may be directly connected with controller 108 and may be configured for operation at a low voltage, e.g., 5 volts. When buttons 260 , 262 are pressed, controller 108 may control valves 252 at the required 120 volts. In this manner, buttons 260 , 262 are safe for the user to operate even in the damp conditions within wash tub 12 without the risk of shock.
Notably, buttons 260 , 262 may be placed directly on dispenser box assembly 200 or in very close proximity to mixing chamber 220 . In addition, buttons 260 , 262 may control valves 252 that are already included on washing machine appliance 100 . This obviates the need for additional hardware required for an independent water delivery system, e.g., nozzles, high voltage circuits, mounting hardware, etc. As a result, the water-on-demand feature provides an inexpensive, reliable, simple, and intuitive system to deliver additional water to wash tub 121 when the user desires. Similarly, because valves 252 and water delivery system are integrated into an existing dispenser box assembly 200 , washing machine appliance 100 may have a more aesthetically pleasing appearance.
Buttons 260 , 262 may be used by a user to deliver an additional amount of water to wash tub 121 on demand, e.g., during or prior to any wash cycle. The additional amount of water may be a specific volume of water or valves 252 may simply be opened for a specific amount of time. For example, according to an exemplary embodiment, pressing hot water button 262 will open valve 252 seated on first valve seat 234 and deliver hot water to detergent compartment 222 or mixing chamber 220 for 20 seconds. However, one skilled in the art will appreciate that water may be delivered for other time durations as controlled by the user, e.g., via settings on controller 108 , or as set by the manufacturer. Indeed, these values may be set by the manufacturer, determined by controller 108 based on the operating parameters selected, selected by the consumer, or set in any other suitable manner.
One skilled in the art will appreciate that the amount of water added to wash tub 121 upon pressing buttons 260 , 262 may vary depending on the application or wash cycle. Similarly, the amount of water delivered may be preset (as described above) such that pressing buttons 260 , 262 delivers the predetermined amount of water. Alternatively, valves 252 may be configured to remain open at all times when corresponding buttons 260 , 262 are depressed. In this manner, a user may precisely control the amount of water added to wash tub 121 . In order to ensure that wash tub 121 is never overfilled, a maximum water level sensor may be included in the wash tub 121 . When water reaches the maximum level, controller 108 may automatically close all valves 252 or perform a drain cycle to prevent water from spilling out of wash tub 121 .
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
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A washing machine having an integrated water-on-demand feature is provided. The washing machine appliance allows a user to adjust the water or wash liquid fill amount of the washing machine appliance using an actuator integrated into or positioned nearby the dispenser box, thereby enabling a simple, convenient, and effective manner of adding wash liquid without requiring a substantial number of additional parts or assembly.
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FIELD OF THE INVENTION
[0001] This invention relates to a method for increasing the particle size of ammonium octamolybdate.
BACKGROUND OF THE INVENTION
[0002] Ammonium octamolybdate (AOM) is known primarily as a fire-retardant. The ability to use AOM to form an image on a substrate is disclosed in WO2002/074548.
[0003] Ammonium octamolybdate (AOM) is a pigment that undergoes a white to black colour change reaction on exposure to laser irradiation. It has become widely used in substrate coding and marking applications using lasers.
[0004] Freshly made AOM pigment powder typically comprises a large proportion of relatively small particles, known as ‘fines’. The presence of these fines is reflected in the DX values of the AOM pigment powder, where X is the percentage of particles below the quoted size, usually in microns.
[0005] With AOM pigment powder the consequence of the presence of a relatively large number of fines is it can adversely affect the rheological properties of any formulation subsequently made using the AOM pigment powder, such as liquid coatings, printing inks or plastic masterbatches.
[0006] In order to apply AOM pigment to a substrate for laser based coding and marking, such as those used in the manufacture of primary or secondary packaging, it must first be formulated into a liquid coating formulation or printing ink. The ink is then applied to the substrate using a standard industrial coating technique.
[0007] It has been observed that AOM pigment, when tested shortly after its manufacture, can give rise to liquid coatings or printing inks with rheological properties far from ideal. Usually the coating rheology is such that the liquid formulation is too thick. With liquid coatings/printing inks there is an ideal rheology window for application to a substrate. Optimum laser imaging performance requires the liquid coating/printing ink to have a specific minimum concentration of AOM pigment powder. Too little pigment causes laser imaging performance to be diminished. Too much pigment can adversely affect laser imaging performance by rendering the liquid coating/printing inks with poor rheological properties which reduces ink transfer during printing. Also having to use more pigment than is usually necessary makes the process less economically attractive.
[0008] For a given concentration of AOM pigment powder if the coating/ink is too thick the coating/ink cannot readily flow or transfer from the printing press to the substrate. This can be remedied by dilution with solvent. However, this causes the active pigment concentration to be diluted resulting in less pigment actually being transferred to the substrate resulting in diminished laser imaging performance. This is critical in applications requiring high contrast such as barcode readability. If the ink is too thin not enough will transfer and laser imaging performance will be diminished.
[0009] We have observed that the particle size of AOM pigment power can naturally increase with time. However, this process can take up to and over 12 months to fully complete. It is costly and impractical to hold large stocks of AOM pigment for such a relatively long time in an industry based on fast turnaround products.
SUMMARY OF THE INVENTION
[0010] In accordance with a first aspect of the invention there is provided a method of increasing the particle size of AOM pigment powder, comprising heating the AOM pigment powder to a temperature (k1) above 20° C. for a given amount of time, t1.
[0011] In accordance with a second aspect of the invention there is provided a method of producing an ink composition comprising formulating AOM pigment powder according to the method of the first aspect of the invention and incorporating this into an ink composition.
[0012] In accordance with a third aspect of the invention there is provided an ink composition obtainable from the method of the second aspect of the invention.
[0013] In accordance with a fourth aspect of the invention there is provided a method for providing an image on a substrate, which comprises applying to the substrate a composition according to the third aspect of the invention, followed by irradiation.
[0014] The method of the invention has been advantageously shown to mimic what happens naturally when AOM is stored over time, but at a much faster rate. Ink compositions of the invention have reduced viscosity and therefore are more useful in imaging applications. Without being bound by theory, it is thought that the method of the invention causes a reduction in the number of fines present, i.e. very small particles in the AOM pigment are thought to dissolve and stick together, thus reducing the viscosity.
DESCRIPTION OF PREFERRED EMBODIMENTS
Particle Size
[0015] Freshly made AOM pigment powder is known to typically comprise many relatively small particles or fines, but also to comprise a bimodal particle size distribution. In order to create coatings and inks with good rheological properties it is preferred that the AOM pigment powder comprises fewer fines and also has a more monomodal particle size distribution.
[0016] Particle size can be measured using any applicable technique such as: sieving, light scattering, sedimentation, image analysis or a Coulter counter. Particle sizes are typically measured using a laser diffraction particle size analyzer.
[0017] The D10 particle size is the size below which 10% of the particles in the sample are smaller. The conditioning treatment of the present invention preferably yields a D10 of at least 0.4 microns, more preferably at least 0.6 microns and even more preferably still at least 0.8 microns.
[0018] The D50 particle size is the size below which 50% of the particles in the sample are smaller. The conditioning treatment of the present invention preferably yields a D50 of at least 1.6 microns, more preferably at least 2.0 microns and even more preferably still at least 2.4 microns.
[0019] The D90 particle size is the size below which 90% of the particles in the sample are smaller. The conditioning treatment of the present invention preferably yields a D90 of at least 5.6 microns, more preferably at least 6.0 microns and even more preferably still at least 6.4 microns.
[0020] The D99 particle size is the size below which 99% of the particles in the sample are smaller. The conditioning treatment of the present invention preferably yields a D99 of at least 10.0 microns, more preferably at least 10.2 microns and even more preferably still at least 10.4 microns.
[0021] The most preferred particle size distribution is monomodal. Bimodal systems whereby the difference between the two peak heights is relatively large are much preferred over those where it is relatively small.
[0022] It has been surprisingly found that AOM pigment can be conditioned and the number of fines reduced and a more monomodal particle size distribution obtained and the subsequent rheological properties of water based printing inks significantly improved using a process that takes at most a few days. This process involves storing the AOM pigment at an elevated temperature above 20° C., preferably above 30° C. and most preferably in the range 30 to 60° C., for a given length of time. The given length of time is preferably at least 4 hours, and is most preferably in the range 4 to 240 hours. The AOM pigment can be heated in a sealed or open container or on a tray. It is preferred that the AOM pigment powder is heated in a sealed/air tight container.
[0023] It has been surprisingly found that the rheological properties can be further improved by cooling the AOM pigment for a given length of time either after or preferably prior to storage at elevated temperature. Even much more surprisingly still the rheological properties can be still further improved by cooling the AOM pigment in an open container thereby exposing the pigment powder directly to the cool atmosphere for a given length of time prior to storage at elevated temperature.
[0024] The AOM pigment is stored for a given length of time below 20° C., most preferably below 10° C. and is typically stored the range 2 to 8° C. The given length of time is preferably at least 4 hours, most preferably in the range 4 to 240 hours. The AOM pigment can be cooled in a sealed/air tight or open container or on a tray. It is preferred that the AOM pigment powder is exposed directly to the cool atmosphere using either an open container or tray, for all or at least some part of its cool storage. The cool atmosphere preferably has a relative humidity in the range 40 to 100%, more preferably 70 to 80%. It is most preferred that the AOM pigment powder is initially stored at the low temperature, k2, in a sealed container, to allow the pigment to cool to ambient temperature. Typically this step takes 24 to 48 hours. Thereafter, preferably the container is opened and the pigment is exposed to the external atmosphere for the remainder of the cooling time, typically a further 24 to 48 hours.
[0025] Once incorporated into the ink composition, the rheological properties of this can be tested using means known in the art. For instance, the AOM pigment is made into a typical water based flexographic printing ink at a pigment loading of more than 50%, typically around 55%. This loading level is required to generate high optical density images, e.g. suitable for barcodes. Important rheological properties of this ink are:
[0026] 1. Initial ink flow: as measured using a Zahn number 2 flow cup at 20° C. Ideally this is in the range 20 to 28 seconds.
[0027] 2. Residual initial ink quantity: ink remaining in the Zahn number 2 flow cup upon cessation of flow. Ideally there should be essentially negligible ink remaining in the flow cup upon cessation of flow.
[0028] 3. Reduction factor: the amount of water needed to reduce the ink to a flow of 20 seconds, Zahn number cup at 20° C. Ideally this is less than or equal to 5%.
[0029] The initial ink flow and reduction factor are usually related. The higher the initial flow usually the more water is required to reduce it to print viscosity. This results in the print viscosity ink having a decreased pigment concentration giving rise to paler laser images.
[0030] Residual initial ink quantity is a good indication of the rheological properties of an ink. An ink with good rheology would generally leave only a thin coating on the walls of the Zahn flow cup upon cessation of flow. An ink with poor rheology will leave a significant and measurable quantity of the ink in the flow cup upon cessation of flow.
[0031] The ink at print viscosity (20 seconds Zahn 2 at 20° C.) can then be applied to a paper based substrate using a flexographic printing technique to deliver a dry coatweight approximately 6±2 grams per square metre.
[0032] The invention also provides ink compositions obtainable by the method of the invention. These may have the additional properties as outlined below.
Binders
[0033] AOM pigment of the present invention may be formulated into a composition that preferably comprises a binder. The binder can be any suitable binder used by the ink/coatings industry. Preferably, the binder is a polymeric binder. Examples of polymeric binders are acrylic polymers, styrene polymers and hydrogenated products thereof, vinyl polymers, polyolefins and hydrogenated or epoxidized products thereof, aldehyde polymers, epoxide polymers, polyamides, polyesters, polyurethanes, sulfone-based polymers and natural polymers and derivatives thereof. The polymeric binder can also be a mixture of polymeric binders.
[0034] Acrylic polymers are polymers formed from at least one acrylic monomer or from at least one acrylic monomer and at least one styrene monomer, vinyl monomer, olefin monomer and/or maleic monomer. Examples of acrylic monomers are acrylic acid or salts thereof, acrylamide, acrylonitrile, C 1-6 -alkyl acrylates such as ethyl acrylate, butyl acrylate or hexyl acrylate, di(C 1-4 -alkyl-amino)C 1-6 -alkyl acrylates such as dimethylaminoethyl acrylate or diethylaminoethyl acrylate and C 1-4- alkyl halide adducts thereof such as dimethylaminoethyl acrylate methyl chloride, amides formed from di(C 1-4 -alkylamino)C 1-6 -alkylamines and acrylic acid and C 1-4 -alkyl halide adducts thereof, methacrylic acid or salts thereof, methacrylamide, methacrylonitrile, C 1-6 -alkyl methacrylates such as methyl methacrylate or ethyl methacrylate, di(C 1-4 -alkylamino)C 1-6 -alkyl methacrylates and C 1-4 -alkyl halide adducts thereof, amides formed from di(C 1-4 -alkylamino)C 1-6 -alkylamines and methacrylic acid and C 1-4 -alkyl halide adducts thereof and crosslinkers such as N,N′-methylenebisacrylamide.
[0035] Examples of styrene monomers are styrene, 4-methylstyrene and 4-vinylbiphenyl. Examples of vinyl monomers are vinyl alcohol, vinyl chloride, vinylidene chloride, vinyl isobutyl ether and vinyl acetate. Examples of olefin monomers are ethylene, propylene, butadiene and isoprene and chlorinated or fluorinated derivatives thereof such as tetrafluroethylene. Examples of maleic monomers are maleic acid, maleic anhydride and maleimide. Examples of acrylic polymers are poly(methyl methacrylate), poly(butyl methacrylate) and styrene acrylic polymers.
[0036] Styrene polymers are polymers formed from at least one styrene monomer and at least one vinyl monomer, olefin monomer and/or maleic monomer. Examples of styrene monomers, vinyl monomers, olefin monomers and maleic monomers are given above. Examples of styrene polymers are styrene butadiene styrene block polymers, styrene ethylene butadiene block polymers, styrene ethylene propylene styrene block polymers.
[0037] Vinyl polymers are polymers formed from at least one vinyl monomer or from at least one vinyl monomer and at least one olefin monomer or maleic monomer. Examples of vinyl monomers, olefin monomers and maleic monomers are given above. Examples of vinyl polymers are polyvinyl chloride and polyvinyl alcohol.
[0038] Polyolefins are polymers formed from at least one olefin monomer. Examples of olefin monomers are given above. Examples of polyolefins are polyethylene, polypropylene and polybutadiene. Aldehyde polymers are polymers formed from at least one aldehyde monomer or polymer and at least one alcohol monomer or polymer, amine monomer or polymer and/or urea monomer or polymer. Examples of aldehyde monomers are formaldehyde, furfural and butyral. Examples of alcohol monomers are phenol, cresol, resorcinol and xylenol. An example of polyalcohol is polyvinyl alcohol. Examples of amine monomers are aniline and melamine. Examples of urea monomers are urea, thiurea and dicyandiamide. An example of an aldehyde polymer is polyvinyl butyral formed from butyral and polyvinyl alcohol.
[0039] Epoxide polymers are polymers formed from at least one epoxide monomer and at least one alcohol monomer and/or amine monomer. Examples of epoxide monomers are epichlorhydrin and glycidol. Examples of alcohol monomers are phenol, cresol, resorcinol, xylenol, bisphenol A and glycol. An example of epoxide polymer is phenoxy resin, which is formed from epichlorihydrin and bisphenol A.
[0040] Polyamides are polymers formed from at least one monomer having an amide group or an amino as well as a carboxy group or from at least one monomer having two amino groups and at least one monomer having two carboxy groups. An example of a monomer having an amide group is caprolactam. An example of a diamine is 1,6-diaminohexane. Examples of dicarboxylic acids are adipic acid, terephthalic acid, isophthalic acid and 1,4-naphthalenedicarboxylic acid. Examples of polyamides are poyhexamethylene adipamide and polycaprolactam.
[0041] Polyesters are polymers formed from at least one monomer having an hydroxy as well as a carboxy group or from at least one monomer having two hydroxy groups and at least one monomer having two carboxy groups or a lactone group. An example of a monomer having a hydroxy as well as a carboxy group is adipic acid. An example of a diol is ethylene glycol. An example of a monomer having a lactone group is carprolactone. Examples of dicarboxylic acids are terephthalic acid, isophthalic acid and 1,4-naphthalenedicarboxylic acid. An example of a polyester is polyethylene terephthalate. So-called alkyd resins are also regarded as belonging to polyester polymers. Polyurethane are polymers formed from at least one diisocyanate monomer and at least one polyol monomer and/or polyamine monomer.
[0042] Examples of diisocyanate monomers are hexamethylene diisocyanate, toluene diisiocyanate and diphenyl methane diiscocyanate.
[0043] Examples of sulfone-based polymers are polyarylsulfone, polyethersulfone, polyphenyl-sulfone and polysulfone. Polysulfone is a polymer formed from 4,4-dichlorodiphenyl sulfone and bisphenol A.
[0044] Natural polymers can be a cellulose, natural rubber or gelatin. Examples of cellulose derivatives are ethyl cellulose, hydroxypropyl cellulose, nitrocellulose, cellulose acetate and cellulose propionate.
[0045] The polymeric binders are known in the art and can be produced by known methods. The polymeric binder can be also produced in situ by UV radiation of a composition comprising monomers, capable of radical polymerisation, and a UV-sensitive initiator.
[0046] Preferred polymeric binders are acrylic polymers, vinyl polymers, aldehyde polymers, epoxide polymers, polyamides, polyesters and natural polymers and derivatives thereof. More preferred polymeric binders acrylic polymers, vinyl polymers, natural polymers and derivatives thereof.
[0047] Even more preferred polymeric binders are poly(methyl methacrylate), poly(butyl methacrylate), polyvinyl alcohol and cellulose. The most preferred polymeric binder is poly(methyl methacrylate).
[0048] Further examples include ‘core-shell’ type polymers such as those comprising a styrene-acrylic acid copolymer and a styrene/ethylhexyl acrylate copolymer, a styrene/butadiene copolymer or a vinyl acetate/crotonic acid copolymer.
[0049] The binder in a liquid ink/coating system can be in the form of a solution or emulsion.
Solvents
[0050] The composition comprising the AOM and binder of the present invention can also comprise a solvent. The solvent can be water, an organic solvent or mixtures thereof. Preferably the solvent is water.
[0051] Examples of organic solvents are C 1-4 -alkyl acetates, C 1-4 -alkanols, C 2-4 -polyols, C 3-6 -ketones, C 4-6 -ethers, nitromethane, dimethylsulfoxide, dimethylformamide, dimethyl-acetamide, N-methylpyrolidone and sulfolane, whereby C 1-4 -alkanols and C 2-4 -polyols may be substituted with C 1-4 -alkoxy. Examples of C 1-4 -alkyl acetates are methyl acetate, ethyl acetate and propyl acetate, isopropyl acetate and butyl acetate. Other examples include: 2-methoxy-1-methylethyl acetate and 2-ethoxy-1-methylethyl acetate. Examples of C 1-4 -alkanols are methanol, ethanol, propanol, isopropanol or butanol, isobutanol, sec-butanol and tert-butanol. Other examples of suitable alcohol are aromatic alcohols such as: benzyl alcohol. Examples of a C 1-4 -alkoxy-derivatives thereof are 2-ethoxyethanol and 1-methoxy-2-propanol. Examples of C 2-4 -polyols are glycol and glycerol. Examples of C 3-6 -ketones are acetone, methyl ethyl ketone and cyclic ketones such as: cyclohexanone and lactones such as: 4-butyrolactone. Examples of C 4-6 -ethers are dimethoxyethane and diisopropylethyl, cyclic ethers such as: tetrahydrofuran, glycol ethers such as diethylene glycol, glycol ether esters and dialkyl glycol ethers. An example of a C 2-3 -nitrile is acetonitrile. Other solvents include straight, branched and cyclic hydrocarbons including aliphatics such as: heptane, hexane and cyclohexane; and aromatics such as: solvent naphtha (petroleum) light aromatic, toluene, xylenes and ethyl benzene.
[0052] More preferably, the solvent is water, a C 1-4 -alkanol, for example ethanol, a C 1-4 -alkyl acetate, for example ethyl or propyl acetate, or mixtures thereof, or a C 3-6 -ketone such as acetone or methyl ethyl ketone.
Inks
[0053] A composition of the present invention comprising the AOM pigment and binder can be an ink or surface coating formulation. The ink formulation can be a flexographic, gravure, offset, litho, pad or screen printing ink. The ink formulation can be aqueous or solvent based. Another type of ink that the AOM of the present invention is particularly suited for are UV flexo inks. These are inks that usually comprise photo-initiators and resins. The substrate coated with a UV flexo ink is exposed to UV light and a chemical reaction takes place during which the photo-initiators cause the ink components to cross-link into a solid, thereby hardening/curing or drying the ink. The ink comprising the AOM of the present invention can also be electron-beam cured or chemically cured.
[0054] The AOM can also be included into a ‘masterbatch concentrate’ formulation from which coating/ink compositions for laser imaging substrates can be subsequently manufactured. Examples of these systems are taught in WO2013/192307.
Other Additives
[0055] The composition of the present invention comprising AOM and a binder can also comprise other additives. Examples include: polymers, light/energy-absorbing agents, UV-absorbers such as 2-hydroxy-4-methoxybenzophenone, surfactants, waxes, silicones, wetting agents, foam control agents, drying promoters, colourants such as traditional dyes and pigments, fluorescent agents, plasticisers, optical brighteners, oxidizing or reducing agents, stabilizers, light stabilizing agents such as hindered amines, rheology modifiers such as thickening agents such as silica, thinning agents, thixotropy modifiers, dispersing agents, humectants, solvents, adhesion promoters, acid or base-generating agents, acid or base-scavenging agents, opaficiers or retarders.
Substrates
[0056] Other aspects of the invention are a method of coating a substrate with a product of the present invention, and the coated substrate. The substrate can be a sheet or any other three-dimensional object and it can be transparent or opaque. The substrate can be cellulose fibre based such as: paper, corrugated fiberboard, cardboard and cartonboard; metal; metallic foil; wood; textiles; leather; glass; ceramics and/or polymers. Examples of polymers are polyethylene terephthalate, low density-polyethylene, polypropylene, biaxially orientated polypropylene, polyether sulfone, polyvinyl chloride, polyester and polystyrene. Preferably, the substrate is made from paper, corrugated fiberboard, cardboard or polymeric film. Also preferably, the substrate is a flexible polymer film made from polyethylene terephthalate, low density-polyethylene, polypropylene, biaxially orientated polypropylene, polyether sulfone, polyvinyl chloride or cellulosic films. The substrate can also be a ridged plastic object, a foodstuff or pharmaceutical preparation.
[0057] The thickness of the coating usually chosen is in the range of 0.1 to 1000 microns. Preferably, it is in the range of 1 to 500 microns. More preferably, it is in the range of 1 to 200 microns. Most preferably, it is in the range of 5 to 150 microns.
[0058] The substrate can be coated with a composition of the present invention by using a standard coating application such as a bar coater application, rotation application, spray application, curtain application, dip application, air application, knife application, screen, blade application or roll application.
[0059] Where the composition of the present invention is a liquid ink formulation it can be applied to substrates using any known printing method. Examples include offset, intaglio, flexographic, gravure, UV flexo, pad printing, screen printing and the like.
[0060] The coating composition can be dried, for example at ambient or elevated temperature or via energy curing such as UV or electron beam.
Plastics
[0061] The AOM pigment powder of the present invention can also be used in the laser marking of plastics, particularly thermoplastics, wherein the AOM pigment powder has been directly incorporated into the plastic using a high temperature melt processing procedure such as injection moulding or extrusion.
Lasers/Laser Systems
[0062] Also part of the invention is a process for preparing a marked substrate, which comprises the steps of i) coating a substrate with the composition of the present invention, and ii) exposing those parts of the coated substrate, where a marking is intended, to energy in order to generate a colour marking.
[0063] The energy can be heat or any other energy, which is transformed into heat when applied to the substrate coated with the composition of the present invention. Examples of such energy are UV, IR which include near and mid-IR or microwave irradiation.
[0064] The energy can be applied to the coated substrate in any suitable way, for example heat can be applied by using a thermal printer, such as those that comprise a thermal print head that contacts the substrate. The energy can also be in the form of electromagnetic radiation or light, preferably in the wavelength range 100 nm to 32 microns. The light can be coherent or non-coherent, broadband or monochromatic. UV, visible and IR irradiation can be applied by using UV, visible or IR light sources such as lamps, bulbs and diodes, or more preferably lasers. Lasers can be pulsed or continuous wave emitters. Examples of IR lasers are CO 2 lasers that emit in the mid-infrared, Nd:YAG or fibre lasers and IR semiconductor lasers that emit in the near infrared. Preferably, the energy is IR irradiation. More preferably, the energy is IR irradiation having a wavelength in the range of 700 nm to 20 microns. Most preferably, the energy is IR irradiation such as that generated by a mid-infrared CO 2 laser or that generated by a near infrared Nd:YAG laser. Semi-conductor diode lasers also suitable for example: AlGaInP, AlGaAs or InGaAsP based systems. UV laser radiation in the wavelength range 100 nm to 405 nm is also suitable. The light can be emitted from a single source or multiple sources, such as in a diode array, laser array or laser diode array system.
Other Colour Change Chemistries
[0065] The composition of the present invention can also comprise other colour change chemistries. Examples include other metal oxyanions, leuco dyes with or without an additional colour developer, charge transfer agents and charrable agents and poly-yne compounds.
Plastics Imaging
[0066] The composition of the present invention is also particularly suitable for use in the imaging, coding and marking of plastics, particularly with lasers. To do this the AOM of the present invention is dispersed within the bulk of the plastics. The AOM of the present invention can be applied to the plastics as a powder, or via a liquid or solid masterbatch. A suitable liquid masterbatch comprises the AOM of the present invention dissolved, or preferably dispersed, into a polymer compatible liquid vehicle. Suitable liquid vehicles include but are not limited to vegetable or mineral oils. Preferably the liquid vehicle is compatible with both the AOM of the present invention and the plastics. A suitable solid masterbatch comprises the AOM of the present invention dissolved, or preferably dispersed in a solid plastics. Plastics suitable for use in preparation of a solid masterbatch comprising AOM of the present invention include, but are not limited to, carriers such as: HDPE, LDPE, LLDPE, PPHP, PPCP, ABS, SAN, GPPS, HIPS, PC, PA, POM, PMMA, PBT/PET and PVC. The AOM of the present invention can be applied to plastics in combination with other additives such as colourants, toners, UV absorbers, light stabilizing agents, reheat agents, nucleators, clarifiers, anti-acetaldehyde agents, anti-slip agents, delustrants, pearlescent and metallic effect pigments and oxygen scavengers. The AOM of the present invention can be applied to the plastic using methods such as injection moulding, blow moulding, profile extrusion, sheet extrusion and film extrusion application methods.
Energy/Light-Absorbing Agents
[0067] The composition of the present invention can also comprise an energy or light-absorbing agent. These can absorb light in the region 100 nm to 32 microns. Particularly preferred are compounds that absorb in the near infrared region of the spectrum (700 nm to 2500 nm). The compounds are known as NIR absorbers. Any suitable NIR absorber can be used. It is even more preferred still if the absorbance profile or λmax of the NIR absorber approximately matches the emission wavelength(s) of the NIR light source or laser used to image the substrate. Also preferred are NIR absorbers that have negligible impact on the background colour of the substrate. The most preferred NIR absorbers include: 1) inorganic copper salts such as copper (II) hydroxyl phosphate; 2) organic NIR dyes and pigments, such as N,N,N,′N′-tetrakis(4-dibutylaminophenyl)-p-benzoquinone bis(iminium hexafluoroantimonate); 3) non-stoichiometric inorganic compounds, such as reduced indium tin oxide, reduced zinc oxide, reduced tungsten oxides, metal tungsten bronzes such as cesium tungsten bronze, reduced antimony tin oxide; also included in this are doped metal oxides such as AZO and FTO; and 4) conductive polymers such as PEDOT and the like.
[0068] Other energy-absorbing additives include UV absorbers, visible light absorbers and mid-infrared absorbers particularly those that can improve imaging with a CO 2 laser. Examples include mica and mica based compounds such as ATO-coated micas known as Iriodin products.
[0069] The following Examples illustrate the invention.
EXAMPLES
[0070] Cool treatment was performed using a walk-in cold store fridge set to an operating temperature in the range 4-8° C.
[0071] Heat treatment was performed using a walk-in heated chemical store set to an operating temperature in the range 40-50° C.
[0072] Particle size distribution was measured using a laser diffraction particle size analyzer.
[0073] 6 different samples of AOM pigment were prepared as followed from the same batch of AOM pigment starting material:
AOM Pigment Sample 1—Untreated.
[0074] D10=0.37; D50=1.30; D90=5.54; D99=9.67; with distinct bimodal distribution.
AOM Pigment Sample 2—Fridge only treated in a sealed container, untreated AOM cooled at 6±2° C. for 96 hours in a sealed container throughout. No heat treatment.
AOM Pigment Sample 3—Fridge only treated in an open container, untreated AOM cooled at 6±2° C. for 96 hours in an open container throughout. No heat treatment.
The particle sizes of samples 2 and 3 were not measured as their rheological properties were no better than the untreated sample.
AOM Pigment Sample 4—Heat only treated AOM, untreated AOM heat treated in a sealed container for 120 hours at 45±5° C. No cool treatment.
D10=0.71; D50=2.77; D90=6.41; D99=10.23; with distinctly reduced bimodal distribution.
AOM Pigment Sample 5—Cooled and heat treated AOM sealed, untreated AOM cooled at 6±2° C. for 96 hours. The cooled AOM Pigment was then heat treated at 45±5° C. for 96 hours, in a sealed container throughout.
AOM Pigment Sample 6—Cooled and heat treated AOM part open then sealed during cooling, untreated AOM cooled at 6±2° C. for 48 hours in a sealed container, after which time the container lid was removed allowing the pigment direct contact with the cooled atmosphere at 6±2° C./75±5% RH for a further 48 hours. After this time the lid was replaced sealing the container. The cooled AOM pigment was then heat treated at 45±5° C. for 96 hours.
D10=0.80; D50=2.82; D90=6.57; D99=10.35 with distinct monomodal distribution.
Samples 2 to 6 were prepared by placing 25 kg of the pigment into a polyethylene bag which was then put into a 30 L metal pail fitted with a ring and latch lid.
[0075] Each of the above 6 AOM pigments was then formulated into a water based flexographic printing ink as follows:
[0000] 1. Acrylic binder=20%
2. Water=20%
3. Defoamer=1.5%
[0076] 4. Adhesion promoter=1.5%
5. Diethylene glycol=2%
6. AOM Pigment=55%
[0077] Each ink was prepared using a high shear Silverson mixer until a sub 5 micron particle size had been obtained.
[0078] Each ink was tested as follows:
[0000] 1. Initial Zahn Cup number 2 flow at 20° C., measured in seconds.
2. Residual initial ink remaining in Zahn number 2 cup, measured in grams.
3. Reduction factor, amount of water required to reduce ink to print viscosity of 20 seconds, Zahn number 2 flow cup at 20° C., given as a percentage.
RESULTS
[0079]
[0000]
Initial ink
Residue
flow Zahn 2
from Zahn
Reduction to 20 s
cup at 20° C.
2 cup
Zahn 2 at 20° C.
(seconds)
(grams)
(%)
AOM Pigment Sample 1 -
46
5.1
13.5
Untreated
AOM Pigment Sample 2 -
59
6.1
13.0
Fridge treatment only,
sealed
AOM Pigment Sample 3 -
54
5.3
12.1
Fridge treatment only, open
AOM Pigment Sample 4 -
42
3.0
9.2
Heat treatment only, sealed
AOM Pigment Sample 5 -
40
0.9
8.5
Fridge and heat, sealed
throughout
AOM Pigment Sample 6 -
28
0.1
4.5
Fridge part sealed/part
open, heat treatment sealed
CONCLUSIONS
[0080] An ideal water based flexographic printing ink would have initial flow at 20-28 seconds Zahn 2 flow cup at 20° C., with essentially negligible residue remaining in the cup and a reduction factor ≦5%.
[0081] Both of the cool treatments only had little overall effect.
[0082] Heat treatment only significantly improved rheological properties.
[0083] Cool and heat treatment, sealed throughout gave a further improvement.
[0084] The best rheological properties were obtained by the cooling the pigment in a sealed container but removing the lid to expose the pigment directly to the atmosphere prior to replacing the lid for heat treatment.
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Methods of increasing the particle size of ammonium octamolybdate (AOM) pigment powder are provided. A method can include heating the AOM pigment powder to a temperature above 20° C. for a given amount of time. An ink composition can be produced by formulating AOM pigment powder with increased particle size and incorporating the AOM pigment powder into an ink composition.
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This application claims the benefit of provisional application No. 60/117,482, field Jan. 27, 1999
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to components for weapon system. More specifically, this invention relates to multi-lugged bolts, bolt carriers, and barrels for rifles.
2. Description of Related Art
A wide variety of bolt, bolt carriers and barrels are well known in the art. Typically such devices have lugs of the same size, regardless of the load bearing on the lugs, and which are evenly spaced around the face of the bolt, with the possible exception of the area required for the extractor. The following well known rifles have multi-lugged bolts and bolt carriers: the Johnson Model 1941 rifle and machine gun developed by Melvin Johnson; the M16/AR15 and Stoner 63 Weapons System developed by Eugene Stoner; the AR18 Rifle developed by Armalite; the Daewoo military and Sporting Rifles developed by the Korean company Daewoo; and the Steyer AUG rifle made in Austria. Other similar rifles are well known in the art.
SUMMARY OF THE INVENTION
It is desirable to provide a bolt and bolt carrier for rifles that permits ammunition to be fed from a variety of ammunition feeding devices, such as box magazines, clip magazines and ammunition belts while providing improved fatigue strength during the firing sequence. It is also desirable to provide a bolt and bolt carrier device that can be easily adapted in the field by the operator without the use of special tools to reconfigure the gun to fire a variety of cartridges, including but not limited to: 0.223 Rem (5.56×45 mm); 7.62×39 mm; and 5.45×39 mm. It is desirable to provide a bolt carrier that is designed to accept the bolt and to glide over a variety of magazines. In particular, it is desirable to provide a bolt with improved lug strength and failure resistance.
Therefore, it is the general object of this invention to provide an improved bolt and bolt carrier for automatic rifles that is compatible with receiving ammunition from a variety of feeding devices.
It is a further object of this invention to provide an improved bolt and bolt carrier for automatic rifles that can be easily adapted to fire a wide variety of well-known cartridges.
Another object of this invention to provide an improved bolt and bolt carrier for automatic rifles with improved lug strength and durability.
A still further object of this invention to provide an improved bolt and bolt carrier for automatic rifles that has an improved failure rate.
A further object of this invention to provide an improved bolt and bolt carrier for automatic rifles that has heavier lugs on each side of the extractor, that are adapted to receive without failure additional loading.
These and other objects of this invention are achieved by the invention as described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view of the preferred bolt carrier and bolt of this invention.
FIG. 2 is a left side view of the preferred bolt carrier and bolt of this invention.
FIG. 3 is a right side view of the preferred bolt carrier and bolt of this invention.
FIG. 4 is a disassembled view of the major components of and related to the preferred bolt carrier and bolt of this invention.
FIG. 5 is a detailed drawing of the preferred bolt of this invention showing the preferred component parts.
FIG. 6 is a detailed mechanical drawing showing the preferred lug placement and relative sizes of the lugs and gaps of the preferred bolt of this invention.
FIG. 7 is a perspective view of the lug mating between the preferred bolt and the barrel extension bolt head cavity of this invention.
FIG. 8 is a perspective view of the preferred barrel assembly of this invention.
FIG. 9 is a side section view of the bolt head cavity of the preferred barrel of this invention.
FIG. 10 is an end view of the preferred barrel bolt head—bolt interface of this invention.
FIG. 11 is an end view of the preferred barrel bolt head—bolt interface of this invention showing the bolt being rotated into engagement.
FIG. 12 is an end view of the preferred barrel bolt head—bolt interface showing the lug interaction between the bolt and the bolt head.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the figures and particularly to FIG. 1 showing the preferred bolt carrier 100 with the preferred bolt 101 inserted in the bolthole (not shown). The bolt carrier 100 has an operation rod hole 103 with an operation rod catch 102 for receiving and retaining the operation rod. The preferred bolt 101 is provided with six lugs 601 , 603 , 605 , 607 , 609 , 611 on the bolt head 201 . An extractor 104 as well as an ejector slot 106 are provided generally opposite each other on the bolt head 201 . Indentations 105 a ,b are provided to permit the bolt carrier 100 to fit to a wide variety of ammunition magazines.
FIG. 2 shows the left side view of the preferred bolt carrier 100 and bolt 101 of this invention. The bolt head 201 is shown fixed to the end of the bolt shaft 204 . A cam slot 202 is provided on the left side of the bolt carrier 100 , through which a cam pin 203 can be seen. The operation rod hole 103 is also shown in perspective view.
FIG. 3 shows the right side view of the preferred bolt carrier 100 of this invention. This view provides additional detail as to the bolt lug head 201 of this invention.
FIG. 4 shows the major components and related components of the preferred bolt carrier 100 and bolt 101 of this invention in disassembled but close proximity to each other. The bolt 101 is shown with the bolt head 201 extended away from the bolthole 307 in the bolt carrier 100 . A cam 301 is shown adapted to mechanically interact with the bolt 101 through the cam slot 202 . An operation rod catch 302 is provided, which is insertable into the catch opening 308 in the bolt carrier 100 . A bolt catch retension pin 303 is provided to hold the operation rod catch 302 in place by insertion into the pin hole 309 after inserting the operation rod catch 302 in the bolt carrier 100 . A firing pin 305 is provided with a carrier end 306 , both of which are adapted to be held in place within the bolt carrier 100 by a carrier end pin 304 which is inserted into an carrier pin hole 310 , after insertion of the firing pin 305 and carrier end 306 , thereby holding each in place.
FIG. 5 shows a detailed perspective view of the preferred bolt 101 of this invention. An extractor 505 is fixed to the bolt 101 by an extractor pin 501 , which is adapted to be positioned inside 506 the bolt 101 with each end 507 and 508 pressed through pin holes 503 and 502 respectively. A spring 504 is provided to give tension to the extractor 505 , while simultaneously holding the extractor pin 501 in place. The extractor pin 501 is stepped 509 and 510 to keep the extractor pin 501 in place.
FIG. 6 shows the detailed mechanical drawing of the bolt head 201 face of the preferred bolt 101 with each lug 601 , 603 , 605 , 607 609 and 61 land lug space 602 , 604 , 606 , 608 , 610 and 612 shown. The extractor slot 104 is shown at the top of the bolt head 201 with the ejector slot 106 shown generally at the bottom of the bolt head 201 . The relative sizes and positions of the six lugs 601 , 603 , 605 , 607 , 609 , 611 are important to this invention. For example, the top two lugs 601 and 611 on either side of the extractor slot 104 are generally the same size 622 and 623 and are generally wider than the other lugs 603 , 605 , 607 , 609 , each of which is generally the same size 624 , 625 , 626 , 627 . In the preferred embodiment of this invention, the bolt head 201 lugs 601 , 603 , 605 , 607 , 609 , 611 are symmetrically positioned about the axis 613 , with the gaps between the respective lugs matched. For example, the preferred gap 602 between the lugs 601 and 603 is generally the same width as the gap 610 between the lugs 609 and 611 . The preferred gap 604 between lugs 603 and 605 is generally the same width as the gap 608 between the lugs 607 and 609 . The largest gap 612 is between the extractor slot 104 and the second largest gap 606 is over the ejector slot 106 . Also, in the preferred embodiment of the bolt head 201 of this invention the distance from axis 613 to point 616 is generally the same as the distance from axis 613 to point 614 , and the distance from axis 613 to point 617 is generally the same as the distance from axis 613 to point 615 . In this way the design of the preferred bolt head is generally symmetrically. The reader should note that while the ejector slot 106 is shown somewhat closer to lug 605 than lug 607 , alternatively, the ejector 106 can be orientated closer to lug 607 or can be positioned at an equal distance from lug 605 and 607 .
This bolt head 201 is designed to fit to the barrel extension 701 , which has a bolt head cavity 703 having protrusions where the bolt head 201 has lugs and lugs where the bolt head 201 has spaces.
FIG. 7 shows a perspective view of the preferred mating between the bolt head 201 and the bolt head cavity 703 of the barrel extension 701 , showing how the bolt head 201 lugs 601 , 603 , 605 , 607 , 609 , 611 mate with bolt head cavity 703 gaps 704 , 705 , 706 , 707 , 708 , 709 .
FIG. 8 shows a perspective view of the preferred barrel 800 having a sight 801 attached. Detail of the bolt head cavity 703 with the gaps 704 , 705 , 706 , 707 , 708 , 709 are shown.
FIG. 9 shows a cut-away view of the barrel 800 bolt head cavity 703 showing the chamber 901 .
FIG. 10 shows an interior cut-away view of the bolt head cavity 703 with the bolt head 201 , with the bolt head 201 lugs 601 , 603 , 605 , 607 , 609 , 611 inserted in the gaps 704 , 705 , 706 , 707 , 708 , 709 of the bolt head cavity 703 .
FIG. 11 shows the interior cut-away view of the bolt head cavity 703 with the bolt head 201 inserted and rotated.
FIG. 12 shows the interior cut-away view of the bolt head cavity 703 with the bolt head 201 inserted and rotated as well as showing the relative positions of the extractor 104 and the ejector 106 .
The foregoing description is of a preferred embodiment of the invention and has been presented for the purposes of illustration and as a description of the best mode of the invention currently known to the inventors. It is not intended to be exhaustive or to limit the invention to the precise form, connections, or choice of components disclosed. Obvious modifications or variations are possible and foreseeable in light of the above teachings. This embodiment of the invention was chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable on of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when they are interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled.
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An improved bolt, bolt carrier and barrel assembly for rifles is described. This invention provides bolt mechanism that has heavier lugs on each side of the extractor to distribute the forces more equally and reliably and thereby reducing firearm failure rate. Moreover, this invention provides a bolt system that is easily adaptable to different ammunition feed devices as well as different ammunition cartridges. This invention further includes a barrel having a barrel extension designed to mate to the symmetrical bolt head lugs of this invention.
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CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Priority of U.S. Provisional Patent Application Ser. No. 61/046,118, filed Apr. 18, 2008, incorporated herein by reference, is hereby claimed.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable
REFERENCE TO A “MICROFICHE APPENDIX”
[0003] Not applicable
BACKGROUND OF THE INVENTION
[0004] 1. Field of the Invention
[0005] The present invention relates to continuous batch washers or tunnel washers. More particularly, the present invention relates to an improved method of washing textiles or fabric articles (e.g. clothing, linen, etc.) in a continuous batch tunnel washer wherein the textiles are moved sequentially from one module or zone to the next module or zone including initial pre-wash zones, a plurality of main wash and pre-rinse zones, and then transferred to an extractor that removes water. More particularly, the present invention relates to an improved method of washing textiles in a continuous batch tunnel washer wherein a counter flow of wash liquor from one module or zone to the next module or zone is stopped, allowing for a standing bath. Chemicals are then added to separate soil from the goods and suspend the soil in the wash liquor. After a period of time, counter flow is commenced again to remove the suspended soil. The pre-rinsed goods are spray rinsed during extraction of excess water so that soil is not redeposited eliminated graying of the goods.
[0006] 2. General Background of the Invention
[0007] Currently, washing in a commercial environment is conducted with a continuous batch tunnel washer. Such continuous batch tunnel washers are known (e.g. U.S. Pat. No. 5,454,237) and are commercially available (www.milnor.com). Continuous batch washers have multiple sectors, zones, stages, or modules including pre-wash, wash, rinse and finishing zone. Commercial continuous batch washing machines utilize a constant counter flow of liquor and a centrifugal extractor or mechanical press for removing most of the liquor from the goods before the goods are dried. Some machines carry the liquid with the goods throughout the particular zone or zones.
[0008] Currently, a counter flow is used during the entire time that the fabric articles or textiles are in the main wash module zone. This practice dilutes the washing chemical and reduces its effectiveness. Additionally, while the bath liquor is being heated, this thermal energy is partially carried away by the counter flow thus wasting energy while a desired temperature value is achieved.
[0009] A final rinse with a continuous batch washer has been performed using a centrifugal extractor or mechanical press. In prior art systems, if a centrifugal extractor is used, it is typically necessary to rotate the extractor at a first low speed that is designed to remove soil laden water before a final extract.
[0010] Patents have issued that are directed to batch washers or tunnel washers. The following table provides examples.
[0000]
TABLE
PATENT NO.
TITLE
ISSUE DATE
4,236,393
Continuous tunnel batch washer
Dec. 02, 1980
4,485,509
Continuous batch type washing
Dec. 04, 1984
machine and method for operating
same
4,522,046
Continuous batch laundry system
Jun. 11, 1985
5,211,039
Continuous batch type washing
May 18, 1993
machine
5,454,237
Continuous batch type washing
Oct. 03, 1995
machine
BRIEF SUMMARY OF THE INVENTION
[0011] The present invention improves the current art by reducing water consumption, improving rinsing capability, reducing the number of components required to perform the function of laundering fabric articles or textiles, and saving valuable floor space in the laundry.
[0012] The present invention reduces and/or combines zones, sectors, or modules and improves the method of processing the textiles. Rinsing is done in two zones, first in the continuous batch washer itself in an intermediate rinse zone after each main wash zone(s) and a pre-rinse in the last zone(s). A final rinse is then done in a mechanical water removal machine such as a centrifugal extractor or mechanical press.
[0013] When the goods are initially transferred into the main wash modules, the counter flow of wash liquor into the modules is stopped allowing for a standing bath. Chemicals are added to separate the soil from the goods and suspend the soil in the wash liquor. If needed, the wash liquor to the separate module bath is raised in temperature to facilitate the release of soil from the goods and activate the chemicals.
[0014] Once the soil has been released from the textiles, there is no more work for the chemicals to perform. At this time, the process can be described as “chemical equilibrium”. At this point, water by counter flow is commenced to remove the suspended soil. This rinsing is termed “intermediate rinse” in the wash zone(s) and a pre-rinse after the last wash zone. A final rinse can be performed in a centrifugal extractor or mechanical press.
[0015] The process of the present invention uses fresh water that can be supplied through an atomizing nozzle while the goods are being extracted. Because the free soil has already been removed in the pre-rinse zone, the spray rinse while extracting will not re-deposit soil on the linen thereby reducing or eliminating graying of the goods. It is not necessary to centrifuge (and drain at a low speed) the soil laden water before the final extract. With the present invention the process time is reduced. The amount of fresh water required compared with conventional processes is reduced.
[0016] The method of the present invention uses less water than in current art because the counter flow is stopped for part of the cycle. The spray rinse in the centrifugal extractor or mechanical press is more effective than the current practice of draining the free water from the linen and then refilling.
[0017] The method of the present invention preserves the washing effectiveness of current counter flow washers to wash heavy soil classifications because the amount of soil dilution is the same even though there are less zones, stages, or modules. The present invention provides a higher effective rinsing provided by the spray rinse in the centrifugal extractor because of the pre-rinse.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0018] For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein:
[0019] FIG. 1 is a schematic diagram showing the preferred embodiment of the apparatus of the present invention;
[0020] FIG. 2 is a schematic diagram showing the preferred embodiment of the apparatus of the present invention;
[0021] FIG. 3 is a schematic diagram showing the preferred embodiment of the apparatus of the present invention;
[0022] FIG. 4 is a schematic diagram of an alternate embodiment of the apparatus of the present invention;
[0023] FIG. 5 is a schematic diagram of the alternate embodiment of the apparatus of the present invention;
[0024] FIG. 6 is a partial perspective view of the alternate embodiment of the apparatus of the present invention;
[0025] FIG. 7 is a partial perspective view of the preferred embodiment of the apparatus of the present invention;
[0026] FIG. 8 is a fragmentary perspective view of the alternate embodiment of the apparatus of the present invention showing the starch dispensing nozzle tube;
[0027] FIG. 9 is a fragmentary perspective view of the alternate embodiment of the apparatus of the present invention showing the starch dispensing nozzle tube; and
[0028] FIG. 10 is a fragmentary perspective view of the alternate embodiment of the apparatus of the present invention showing the starch dispensing nozzle tube.
DETAILED DESCRIPTION OF THE INVENTION
[0029] FIGS. 1-3 shows a schematic diagram of the textile washing apparatus of the present invention, designated generally by the numeral 10 . Textile washing apparatus 10 provides a tunnel washer 11 having an inlet end portion 12 and an outlet end portion 13 . In FIG. 1 , tunnel washer 11 provides a number of modules 14 - 18 . These modules 14 - 18 can include a first module 14 and a second module 15 which can be pre-wash modules. The plurality of modules 14 - 18 can also include modules 16 , 17 and 18 which are main wash and pre-rinse modules.
[0030] The total number of modules 14 - 18 can be more or less than the five (5) shown in FIG. 1 . FIG. 2 shows an alternate arrangement that employs a tunnel washer 11 having eight (8) modules 14 - 18 and 35 - 37 . FIG. 3 shows an alternate arrangement that employs a tunnel washer 11 having ten (10) modules 14 - 18 and 35 - 39 . In FIG. 2 , the modules 14 , 15 can be pre-wash modules. In FIG. 3 , modules 14 , 15 , 16 can be pre-wash modules. In FIG. 2 , the modules 16 , 17 , 18 and 35 , 36 , 37 can be main wash and pre-rinse modules. In FIG. 3 , the modules 17 , 18 and 35 , 36 , 37 , 38 , 39 can be main wash and pre-rinse modules. Instead of a two (2) or three (3) module pre-wash section (see FIGS. 1 , 2 , 3 ), a single module 14 could be provided as an alternate option for the pre-wash section.
[0031] Inlet end portion 12 can provide a hopper 19 that enables the intake of textiles or fabric articles to be washed. Such fabric articles, textiles, goods to be washed can include clothing, linens, towels, and the like. An extractor 20 is positioned next to the outlet end portion 13 of tunnel washer 11 . Flow lines 21 , 25 , 26 , 27 , 27 A are provided for adding water and/or chemicals to tunnel washer 11 as will be described more fully hereinafter.
[0032] When the fabric articles, goods, linens are initially transferred into the main wash modules 16 , 17 , 18 , a counter flow of wash liquor into these modules 16 , 17 , 18 is reduced, preferably stopped allowing for a standing bath. Chemicals are then added as indicated by arrows 26 , 27 to the modules 16 , 17 and/or 18 . In FIG. 2 , chemicals are added as indicated by arrows 26 , 27 , 27 A to the modules 16 , 17 , 18 , 35 , 36 and/or 37 . In FIG. 3 , chemicals are added to the modules 16 - 18 and 35 - 39 as indicated by the arrows 26 , 27 , 27 A. In FIGS. 1-3 , these chemicals separate the soil from the goods, linens, textiles and suspend the soil in the wash liquor. During this step of the method of the present invention, the wash liquor temperature can be elevated if needed to facilitate the release of soil from the goods, fabric articles or linens and activate the chemicals.
[0033] Once the maximum soil has been released from the textiles or fabric articles, there is no more work for the chemicals to perform. At this time, the process can be described as chemical equilibrium. The flow of water is stopped for a time period sufficient to release soil from the goods such as for example between about 20 seconds and one hundred twenty (120) seconds. However, this time interval can be between about ten (10) and three hundred (300) seconds.
[0034] After this time interval of having no counter flow, water by counter flow is commenced to remove the suspended soil. This rinsing can be termed pre-rinse. A final rinse is then performed in a centrifugal extractor or mechanical press 20 . The process of the present invention uses fresh water that can be supplied through an atomizing nozzle for example while the goods are being extracted using the extractor 20 . The process of the present invention uses fresh water in the extractor that can be supplied through an atomizing nozzle for example while the goods are being extracted at high speed (e.g. between about 200 and 1,000 g's) using the extractor 20 .
[0035] Flow line 21 transmits water to hopper 19 as indicated by arrow 22 . Flow line 21 also carries water to pre-wash module 15 as indicated by arrow 23 . Arrow 24 indicates a flow of water from module 14 to module 15 as part of the pre-wash.
[0036] In FIG. 1 , flow line 25 adds water for counter flow pre-rinse to module 18 . Such water added via flow line 25 to module 18 flows in counter flow fashion from module 18 to module 17 to module 16 (see arrow 25 A). Arrows 26 and 27 indicate chemical addition to modules 16 and 17 respectively. Chemicals to be added to modules 16 and 17 can include for example detergent, alkalaii, and/or oxidizing agents.
[0037] In FIG. 2 , flow line 25 adds water for counter flow pre-rinse to module 37 . Such water added via flow line 25 to module 37 flows in counter flow fashion from module 38 to module 37 , then 36 , then 35 , then 18 , then to module 17 (see arrow 25 B).
[0038] In FIG. 3 , flow line 25 adds water for counter flow pre-rinse to module 38 . Such water added via flow line 25 to module 38 flows in counter flow fashion from module 38 to module 37 , module 36 , module 35 , module 18 , and module 17 (see arrow 25 C).
[0039] In FIG. 1 , textiles or fabric articles that are pre-washed, washed, and then pre-rinsed in tunnel washer 11 are transferred from module 18 to extractor 20 as indicated schematically by arrow 28 . In FIG. 2 , the textiles or fabric articles that are pre-washed, washed, and then pre-rinsed in tunnel washer 11 are transferred from module 37 to extractor 20 as indicated schematically by arrow 28 . In FIG. 3 , textiles or fabric articles that are pre-washed, washed, intermediately rinsed and then pre-rinsed in tunnel washer 11 are transferred from module 39 to extractor 20 as indicated schematically by arrow 28 .
[0040] The method of the present invention thus conducts rinsing in two zones. Rinsing is first conducted in the tunnel washer 11 in a pre-rinse zone which occurs after the main wash. In FIG. 1 , pre-wash zones can be 14 , 5 . The pre-rinse zone and main wash zone can be modules 16 , 17 , 18 . In FIG. 2 , the pre-wash zone can be modules 14 and 15 while the main wash and pre-rinse zones can be modules 16 , 17 , 18 , 35 , 36 and 37 . In FIG. 3 , the pre-wash zone can be modules 14 and 15 while the main wash and pre-rinse zones can be modules 16 , 17 , 18 , 35 , 36 , 37 , 38 and 39 . The second rinse zone is the final rinse, which is conducted in the extractor 20 or other mechanical water removal machine such as a mechanical press.
[0041] Because the free soil has already been removed in the pre-rinse zone at modules 16 , 17 , 18 of FIG. 1 (or 16 - 18 , 35 - 37 of FIG. 2 or 16 - 18 , 35 - 39 of FIG. 3 ) as part of the method of the present invention, the spray rinse while extracting will not redeposit soil on the linen thereby reducing or eliminating graying of the goods. With the present invention it is not necessary to centrifuge (and drain at a low speed) the soil laden water before the final extract at 20 . With the present invention, the process time is thus reduced. The amount of fresh water required compared with conventional processes is reduced. The spray rinse and the centrifugal extractor 20 or mechanical press is more effective than the current practice of draining the free water from the linen and then refilling the extractor 20 .
[0042] An additional benefit of the pre-rinse concept of the present invention is to permit the mechanical press or extractor to have more time extracting the free water. This result follows because the effect of the pre-rinse is to remove most of the suspended soil. The amount of fresh water required for final rinse is thus greatly reduced. The time for rinsing is reduced, allowing this saved cycle time for water removal.
[0043] The method of the present invention preserves the washing effectiveness of current counter flow washers 11 to wash heavy soil classifications because the amount of soil dilution is the same even though there are fewer zones or stages or modules.
[0044] The present invention provides a higher effective rinsing provided by the spray rinse 30 and the centrifugal extractor 20 because of the pre-rinse that is conducted in the modules 16 , 17 , 18 as discussed above.
[0045] FIGS. 4-10 show an alternate embodiment of the apparatus of the present invention, designated generally by the numeral 40 . The textile washing apparatus 40 of the alternate embodiment can provide the same tunnel washer 11 of the preferred embodiment having the modules 14 - 18 , 35 - 39 provided in any one of the embodiments of FIGS. 1 , 2 or 3 . FIG. 4 shows the embodiment of FIG. 1 having a specially configured starch spray arrangement.
[0046] In FIG. 4 , a starch tank 41 contains starch that is to be injected into the linen, fabric articles, or clothing contained in extractor 20 . Starch for the table linen, clothing, fabric articles is pumped in the first phase of the cycle through a spray nozzle 60 (see FIGS. 8-10 ). Controlled flow metering can be achieved for example using an inverter controlled flow metering device. The precise amount of starch is thus injected into the linen, fabric articles, clothing or the like while in extractor 20 . Excess starch can be removed in a separate tank indicated as starch recovery tank 52 in FIG. 4 . Flow line 53 enables recovered starch in tank 52 to be transferred to starch tank 41 .
[0047] Starch tank 41 contains starch that is to be pumped via flow line 42 to nozzle 60 and then to extractor 20 . Fresh water tank 43 can also be used to pipe fresh water to extractor 20 , flowing through valve 45 to nozzle 60 . Valves 44 , 45 and 46 are provided for controlling the flow of either starch or fresh water or a combination thereof to nozzle 60 as shown in FIG. 4 .
[0048] Flow line 49 is a flow line that carries extracted water to tank 51 as it is purged from the fabric articles, clothing or linens contained in extractor 20 . Starch can be recovered via flow lines 49 , 50 to starch recovery tank 52 . Valves 44 , 47 are provided for valving the flow of starch from tank 41 to extractor 20 via flow line 42 . Valve 48 enables tank 41 to be emptied for cleaning or adding new starch.
[0049] In FIGS. 8-10 , starch spray nozzle 60 is shown in more detail. The spray nozzle 60 can provide an elongated section of conduit or pipe 61 . Spray nozzle 60 has an influent end 62 and a discharge end portion 63 . Conduit 61 provides an open ended bore 64 for conveying starch from flow line 42 to nozzle 60 . Influent end 62 provides a connection 80 for attaching conduit 61 to flow line 42 .
[0050] FIGS. 5-7 illustrate the spray pattern 76 that strikes the wall of drum 57 of extractor 20 as emitted by nozzle 60 . In FIGS. 6 and 7 , extractor 20 provides a drum 57 that provides a chamber 55 having an inlet 56 . Clothes, textiles, linens to be sprayed are discharged from tunnel washer 11 via chute 79 into the chamber 55 of extractor 20 . The extractor 20 is preferably movable between a loading and discharging position. The loading position is shown in FIGS. 5 and 6 . In the loading position, clothes transfer from the tunnel washer 11 to the chamber 55 via chute 79 . Pumps 54 can be used to aid in the transfer of water from tank 43 or starch from tank 41 into chamber 55 via nozzle 60 . The spray nozzle 60 produces a spray pattern 76 that extends substantially across the cylindrical wall 58 of drum 57 as shown in FIGS. 6 and 7 . Drum 57 thus provides an inlet 56 for enabling clothing, textiles, or other fabric articles to be added to the drum 57 interior 55 and a rear circular wall 59 . Notice in FIGS. 6 and 7 that the spray pattern 76 extends generally from inlet 56 to circular wall 59 , thus extending substantially across cylindric wall 58 as shown in FIGS. 6 and 7 . Arrow 77 in FIG. 7 illustrates the width of spray pattern 76 which can be about 16 degrees as an example along cylindrical drum wall 58 .
[0051] A mounting plate 65 can be provided having one or more openings 66 for attaching (for example, bolting) spray nozzle 60 to extractor 20 or to a frame that supports extractor 20 .
[0052] The discharge end portion 63 of spray nozzle 60 provides a nozzle tip 67 . The nozzle tip 67 provides a nozzle outlet 70 formed by side plates 71 , 72 , upper plate 73 and lower plate 74 . Atomizing water nozzle 68 , 69 are provided next to nozzle outlet 70 . The atomizing water nozzle 68 is mounted to upper plate 73 . The atomizing water nozzle 69 is mounted to lower plate 74 as shown in FIGS. 8-10 . Spray nozzle 60 can be equipped with aerating or atomizing nozzles 68 , 69 to control the consistency of the starch in the nozzle 60 , thus preventing starch build-up which might eventually plug of the nozzle 60 .
[0053] As part of the method of the present invention, all starch flow lines 42 , 60 can be purged with hot water from fresh water tank via flow line 75 .
[0054] The following is a list of parts and materials suitable for use in the present invention.
[0000]
PARTS LIST
Part Number
Description
10
textile washing apparatus
11
tunnel washer
12
inlet end portion
13
outlet end portion
14
module
15
module
16
module
17
module
18
module
19
hopper
20
extractor
21
flow line
22
arrow
23
arrow
24
arrow
25
flow line
25A
arrow
25B
arrow
25C
arrow
26
arrow - chemical addition
27
arrow - chemical addition
27A
arrow - chemical addition
28
arrow - textile transfer
29
spray rinse flow line
30
arrow
31
extractor water
32
flow line
33
outlet valve
34
arrow
35
module
36
module
37
module
38
module
39
module
40
textile washing apparatus
41
starch tank
42
flow line
43
fresh water tank
44
valve
45
valve
46
valve
47
valve
48
valve
49
flow line
50
flow line
51
extracted water tank
52
starch recovery tank
53
flow line
54
pump
55
chamber
56
inlet
57
drum
58
cylindrical drum wall
59
circular drum wall
60
spray nozzle
61
conduit
62
influent end
63
discharge end
64
bore
65
mounting plate
66
opening
67
nozzle tip
68
atomizing water nozzle
69
atomizing water nozzle
70
nozzle outlet
71
side plate
72
side plate
73
upper plate
74
lower plate
75
flow line
76
spray pattern
77
arrow
78
drum moving mechanism
79
chute
[0055] All measurements disclosed herein are at standard temperature and pressure, at sea level on Earth, unless indicated otherwise. All materials used or intended to be used in a human being are biocompatible, unless indicated otherwise.
[0056] The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.
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A method of washing fabric articles in a tunnel washer includes moving the fabric articles from the intake of the washer to the discharge of the washer through first and second sectors that are a pre-wash zone. In the pre-wash zone, liquid is counter flowed in the wash interior along a flow path that is generally opposite the direction of travel of the fabric articles. The fabric articles are transferred to a main wash zone, and a washing chemical is added to the main wash zone. At about the same time, counter flow is reduced or stopped. The main wash zone can be heated as an option. After a period of time (for example, between about 20 and 120 seconds) counter flow is resumed or increased. In the wash zone, this is considered an intermediate rinse. After the wash zone(s), the increased counter flow after chemical treatment amounts to a pre-rinse. This pre-rinse ensures that the fabric articles are substantially free of soil or the majority of any soil and substantially free of chemicals when they are transferred to an extractor for final removal of excess water. A final rinse (second rinse) is conducted during extraction of excess water.
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The present application claims benefit of U.S. Provisional Application Ser. No. 60/007,502, filed Nov. 22, 1995.
BACKGROUND OF THE INVENTION
The present invention relates to packaging systems for diluting concentrated materials to a preselected volume with a solvent for the concentrate in which a container for the diluted concentrate is packaged with a pre-measured quantity of the concentrate to be diluted, absorbed onto a carrier. The preselected volume of the solvent for the concentrate may then be added to the container with mixing to provide a predetermined level of dilution of the concentrate in the pre-selected volume of solvent. The present invention further relates to methods for diluting a concentrated material to a preselected volume with a solvent for the concentrate by disposing in a container for the diluted concentrate a pre-measured quantity of the concentrate absorbed on a carrier and then adding to the container the preselected volume of the solvent for the concentrate.
Many products are sold as liquid solutions consisting almost entirely of a solvent, such as water. A substantial reduction in shipping weight and consequential cost savings can be achieved by shipping the product in concentrated form essentially free of all, or nearly all, of the solvent.
Thus, a pre-measured quantity of a product concentrate may be added to a container for the final product to be diluted from the concentrate. The quantity of concentrated product and container size are selected so that a quantity of solvent for the concentrated product may be added to the container effective to dilute the concentrate to the desired strength of the final product. This is performed by the product consumer after shipment of the product and prior to use.
Products that are safe to use as dilute solutions may pose a chemical burn hazard to the skin and mucous membranes in concentrated form. This risk is posed, for example, by quaternary ammonium disinfectants. When a few milliliters of product concentrate are shipped in a container, there may or may not be a risk of chemical burns from concentrated product that may leak or spill out when opened or splash out of the container when water is added by the end-user to dilute the product to its final form. This hazard has prevented such products from being sold as concentrates in containers having sufficient internal volume to prepare the diluted final product by the addition of water. There remains a need for a safe means by which concentrated materials posing a hazard if splashed may be packaged in containers with a larger internal volume for dilution of the concentrate with solvent.
SUMMARY OF THE INVENTION
This need is met by the present invention. It has now been discovered that hazardous concentrates may be safely diluted by first adsorbing the concentrate on an absorbent material, which is then packaged in the container for the diluted concentrate for subsequent dilution with the solvent for the concentrate. The absorbent material allows the solvent to soak in and dissolve the concentrate, which is then released by the absorbent material.
Therefore, according to one embodiment of the present invention, a packaging system is provided for diluting a concentrate to a preselected volume with a solvent for the concentrate, which system includes:
a container for the diluted concentrate having an internal volume to at least the predetermined volume;
an absorbent carrier placed in the container; and
a quantity of the concentrate absorbed onto the carrier;
wherein the quantity of concentrate is pre-measured to provide a predetermined level of dilution of the concentrate in the preselected volume of solvent.
In accordance with one aspect of this embodiment of the present invention, the container bears indicia, preferably permanently affixed, relating information concerning the final diluted concentrate, which is covered with a removable temporary label bearing information concerning the concentrate. A removable temporary label may also be affixed to or printed on the outside of the box of which said bottle is inside. Thus, the packaging system containing the concentrate is shipped bearing a label describing the concentrate. After the concentrate is diluted, the temporary label is removed to reveal information concerning the final diluted concentrate.
The foregoing labeling system is universally applicable to packaging systems for diluting concentrates, regardless of whether or not the concentrate is absorbed onto an absorbent carrier. Therefore, according to another embodiment of the present invention, a packaging system is provided for diluting a concentrate to a preselected volume with a solvent for the concentrate, which system includes:
a container for the diluted concentrate having an internal volume to at least the preselected volume, bearing indicia on the external surface thereof relating information concerning the diluted concentrate;
a quantity of the concentrate disposed in the container pre-measured to provide a predetermined level of dilution of the concentrate in the preselected volume of solvent; and
a temporary removable label bearing information concerning the non-diluted concentrate and covering the information-relating indicia.
Another embodiment of the present invention provides methods for diluting a concentrate to a preselected volume with a solvent for the concentrate. Methods in accordance with this embodiment of the present invention include the steps of:
disposing in a container for the diluted concentrate having an internal volume to at least the preselected volume, an absorbent carrier having a quantity of the concentrate absorbed thereon, the quantity being pre-measured to provide a predetermined level of dilution of the concentrate in the preselected volume of solvent;
adding to the container the preselected volume of the solvent for the concentrate; and
mixing the solvent and the concentrate so that a uniform homogeneous dilute solution of the concentrate in the solvent is obtained.
Methods in accordance with this embodiment of the present invention may also incorporate the above-discussed labeling system in which the external surface of the container bears indicia relating information concerning the diluted concentrate, which is covered with a temporary removable label bearing information concerning the non-diluted concentrate. In accordance with this aspect of the inventive method, the container is a container bearing indicia on the external surface thereof relating information concerning the diluted concentrate and further includes a temporary removable label bearing information concerning the non-diluted concentrate and covering the information-relating indicia and the method further includes the step of removing the temporary label to reveal the information-relating indicia concomitantly with the step of adding to the container the preselected volume of the solvent for the concentrate and mixing the solvent and the concentrate.
Because the labeling system of the present invention is universally applicable to packaging systems for diluting concentrates, methods in accordance with the present invention for diluting concentrates incorporating the labeling system need not require the concentrate to be absorbed on an absorbent carrier. Therefore, according to yet another embodiment of the present invention, a method is provided for diluting a concentrate to a preselected volume with a solvent for the concentrate. Methods in accordance with this embodiment of the present invention include the steps of:
disposing in a container for the diluted concentrate, having an internal volume to at least the preselected volume, a quantity of the concentrate pre-measured to provide a predetermined level of dilution of the concentrate in the preselected volume of solvent, wherein the container bears indicia on the external surface thereof relating information concerning the diluted concentrate and further includes a temporary removable label bearing information concerning the non-diluted concentrate and covering the information-relating indicia;
adding to the container the preselected volume of the solvent for the concentrate;
mixing the solvent and the concentrate so that a uniform homogeneous dilute solution of the concentrate in the solvent is obtained; and
removing the temporary label to reveal the information-relating indicia concomitantly with the steps of adding to the container the preselected volume of the solvent and mixing the solvent and the concentrate.
The packaging systems and methods of the present invention are not limited to the packaging and dilution of hazardous concentrated materials, but instead are useful in the packaging and dilution of essentially any material that may be shipped as a concentrate. In addition to solving the problems related to hazardous concentrates, the present invention also provides a method by which concentrated materials may be uniformly and accurately dispensed and packaged for subsequent dilution. Other features of the present invention will be pointed out in the following description and claims, which disclose the principles of the invention and the best modes which are presently contemplated for carrying them out.
BRIEF DESCRIPTION OF THE DRAWING
A more complete appreciation of the invention and many more other intended advantages can be readily obtained by reference to the detailed description of the invention when considered in connection with the single FIGURE, which shows a diagrammatic perspective view of a device according to the present invention.
It should be noted that the drawing is not necessarily to scale, but that certain elements have been expanded to show more clearly the various aspects of the present invention and their advantages.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The device in accordance with the present invention is shown in FIG. 1 in which absorbent material 12 is disposed in container 10 with a concentrated material 14 absorbed thereon. Container 10 bears indicia 16 on the external surface 18 thereof. The indicia 16 relates information concerning the concentrated material 14 in its final, diluted form. The external surface 18 of container 10 has a temporary removable label 20 affixed thereto, covering the indicia 16. Fill line 22 on the temporary label indicates the amount of solvent to be added to dilute the concentrated material 14 to its final strength. A similar fill line may also be provided on the external surface 18 of container 10 (not shown). The container 10 is also provided with a spraying means 24 for delivering the final diluted product. However, essentially any conventional delivery means may be employed.
Container 10 has an internal volume of at least the volume required for the final diluted concentrated material. It is preferred that some air space remain in the container to allow for more efficient mixing of concentrate and solvent.
Essentially any container suitable for dispensing a diluted product may be used with the present invention. Suitable materials include, but are not limited to, glass, ceramic, metal and a plastic such as polyethylene, polypropylene, polyester, polystyrene, polyvinyl chloride, and the like. The container volume may be selected to conform to the size of container in which the diluted product is customarily sold.
The absorbent material may be any material possessing capillary and/or absorbent activity with respect to the solvent to be used that does not degrade or fall apart in the solvent. The amount of absorbent material to be used is at least that amount effective to soak up the pre-measured quantity of concentrated material. Examples of suitable absorbent materials include cotton or synthetic gauze, non-woven materials, natural or synthetic sponge, paper, and the like. It is also contemplated that the concentrated material be retained in a proteinaceous or polymeric gel matrix, and for purposes of the present invention, the absorbent material is defined as including such gel matrices. Proteinaceous gel materials include agar and gelatin, while polymeric gel materials include polyalkylene oxides such as polyethylene glycol.
The solvent to be employed may or may not be the solvent used in the diluted form of the product that is customarily marketed. Depending on the product, the solvent may be water, and alcohol such as methanol, ethanol, isopropanol, and the like, petroleum products and derivatives.
In the embodiment depicted in FIG. 1, two ml of a concentrated mixture of quaternary ammonium salts 14, useful in dilute form as a disinfectant, are adsorbed onto absorbent material 12, optionally with perfume, color, etc., according to the art. The quantity of the concentrated material is pre-measured to provide a predetermined level of dilution of the material in the volume of solvent to be used in the container. Larger containers will contain larger quantities of solvent that will require greater amounts of the concentrated material to achieve the desired level of dilution.
Other concentrated materials suitable for use with the present invention include, but are not limited to, electrolyte spray, antibiotic solutions, perfumes, inks and body lotions.
The indicia 16 on the external surface 18 of container 10 are preferably permanently affixed. The indicia may be silk screened on the container surface, applied in the form of a label, or by essentially any well-known conventional technique. This functions as an inner label identifying the diluted material, together with use instructions, appropriate cautions, and information concerning storage and disposal. Information complying with regulatory requirements may also be included.
The temporary label 20 covering indicia 16 on the external surface 18 of container 10 is essentially conventional to the art of temporary labeling. The labels used with the containers of the present invention are prepared from conventional label stock and printed by conventional techniques. Likewise, direct silk screening of containers, when employed, is also be essentially conventional techniques. The temporary label 20 may be laminated or spot-welded with a removable adhesive. The temporary label may also be affixed to portions of container 10 with a permanent adhesive and contain perforations that permit the removal of the portion of the label covering the indicia on the surface of the container. Essentially any conventional technique for affixing a temporary label to a container may be employed.
The devices of the present invention are prepared by absorbing or adsorbing the pre-measured quantity of the concentrated material onto the absorbent material, which is then placed inside an appropriate labeled container. The container is then sealed and packaged for shipment to the consumer.
The consumer then prepares the final diluted product by adding the solvent to be employed, typically, but not limited to water, to the fill line of the container, which reflects the volume of solvent providing the desired level of dilution of the concentrated material for the pre-measured quantity of concentrated material employed. The container is then shaken to mix the solvent and concentrate to form a uniform homogeneous solution. Concomitantly with the addition of solvent and mixing, the temporary label is removed to reveal the indicia on the surface of the container relating information about the final diluted product. This may be performed before the solvent is added, after the product is mixed, or any time during the solvent addition and mixing process. It is preferred that the label not be removed either too far before the solvent is added or too long after the solvent and concentrate are mixed, to insure that the label visible on the surface of the container accurately reflects the container contents.
The dual label system of the present invention may also be employed with prior art packaging systems in which the concentrated material in the container is not adsorbed onto an absorbent material. Likewise, the combination of the absorbent material having a concentrated material absorbed thereto may be disposed in a container having a single label. The single label may contain only information concerning the final diluted product, or it may also contain information concerning the concentrated material.
For purposes of the present invention, the term "concentrated material" refers to materials to be diluted in their essentially pure form, or in the form of a low solvent concentration, in which the solvent is the same solvent to be added by the consumer, or a different solvent in which the material is soluble. Although the packaging system of the present invention was developed for use with materials that posed a chemical burn hazard in their concentrated form, non-hazardous concentrated materials may also be employed. The packaging system of the present invention provides a means by which such non-hazardous concentrated materials may be uniformly and accurate dispensed and packaged for subsequent dilution.
Significantly, however, the present invention permits the safe and convenient dilution of hazardous or non-hazardous concentrated materials, thereby permitting such materials to be shipped in concentrated form in containers with a larger internal volume for dilution of the concentrated material with solvent without the risk of leaking. It is now possible for consumers to safely and conveniently dilute the concentrated material without the risk of receiving chemical burns from splashing of the material. The present invention also provides a convenient means by which information may be related to the consumer concerning the product in both its concentrated and final, diluted form.
As will be readily appreciated, numerous variations and combinations of the features set forth above can be utilized without departing from the present invention as set forth in the claims. Such variations are not regarded as a departure from the spirit and scope of the invention, and all such variations are intended to be included within the scope of the following claims.
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A packaging system for diluting a concentrated material to a preselected volume with a solvent for the concentrate, which system includes:
a container for the diluted concentrate having an internal volume to at least the predetermined volume;
an absorbent carrier disposed in the container; and
a quantity of the concentrate absorbed onto the carrier;
wherein the quantity of concentrate is pre-measured to provide a predetermined level of dilution of the concentrate in the preselected volume of solvent. Methods for diluting a concentrate to a preselected volume with a solvent for the concentrate using the packaging system are also disclosed.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a divisional of U.S. patent application Ser. No. 12/772,497 filed May 3, 2010, now U.S. Pat. No. 7,987,995 B2, which is a divisional of U.S. patent application Ser. No. 11/342,761 filed Jan. 30, 2006, now U.S. Pat. No. 7,708,152 B2 issued May 4, 2010, which claims the benefit under 35 USC 120 of the filing dates of (a.) Provisional Application No. 60/651,050 filed Feb. 7, 2005, (b.) Provisional Application No. 60/654,718 filed Feb. 17, 2005 and (c.) Provisional Application. No. 60/723,312 filed Oct. 4, 2005. The above-identified disclosures are hereby incorporated by reference.
FIELD OF THE INVENTION
This invention relates to a device and method for preparing platelet-plasma concentrates with improved wound healing properties for use as a tissue sealant and adhesive. The product has a fully active (un-denatured) fibrinogen concentration that is several times greater than is found in blood and a platelet concentration that is many times greater than is found in blood.
BACKGROUND OF THE INVENTION
Blood can be fractionated, and the different fractions of the blood can be used for different medical needs. Under the influence of gravity or centrifugal force, blood spontaneously sediments into three layers. At equilibrium, the top low-density layer is a straw-colored clear fluid called plasma. Plasma is a water solution of salts, metabolites, peptides, and many proteins ranging from small (insulin) to very large (complement components).
The bottom, high-density layer is a deep red viscous fluid comprising a nuclear red blood cells (erythrocytes) specialized for oxygen transport. The red color is imparted by a high concentration of chelated iron or heme that is responsible for the erythrocytes' high specific gravity. The relative volume of whole blood that consists of erythrocytes is called the hematocrit, and in normal human beings this can range from about 37% to about 52% of whole blood.
The intermediate layer is the smallest, appearing as a thin white band above the erythrocyte layer and below the plasma layer; this is called the buffy coat. The buffy coat itself has two major components, nucleated leukocytes (white blood cells) and anuclear smaller bodies called platelets (or thrombocytes). Leukocytes confer immunity and contribute to debris scavenging. Platelets seal ruptures in blood vessels to stop bleeding, and deliver growth and wound healing factors to a wound site. Slower speed or shorter duration centrifugation permits separation of erythrocytes and leucocytes from plasma, while the smaller platelets remain suspended in the plasma, resulting in PRP.
A major improvement in making plasma concentrate from whole blood for use in wound healing and as a tissue sealant is described in U.S. Pat. No. 5,585,007; this patent is hereby incorporated by reference in its entirety. This device, designed for placement in a medical laboratory or surgical amphitheatre, used a disposable cartridge for preparing tissue sealant. The device was particularly applicable for stat preparations of autologous tissue sealants. Preparation in the operating room of 5 ml of sealant from 50 ml of patient blood required less than 15 minutes and only one simple operator step. There was no risk of tracking error because processing can be done in the operating room. Chemicals added could be limited to anticoagulant (e.g., citrate) and calcium chloride. The disposable cartridge could fit in the palm of the hand and was hermetically sealed to eliminate possible exposure to patient blood and ensure sterility. Adhesive and tensile strengths of the product were comparable or superior to pooled blood fibrin sealants made with precipitation methods. Use of antifibrinolytic agents (such as aprotinin) was not necessary because the tissue sealant contained high concentrations of natural inhibitors of fibrinolysis from the patient's blood. This new tissue sealant also optionally contained patient platelets and additional factors that promote wound healing, healing factors that are not present in commercially available fibrin sealants.
This device used a new sterile disposable cartridge with the separation chambers for each run. Since the device was designed to be used in a normal medical setting with ample power, the permanent components, designed for long-term durability, safety and reliability, were relatively heavy, using conventional centrifuge motors and accessories.
Small, self-contained centrifugal devices for obtaining platelet concentrates from blood are described in commonly assigned, copending application Ser. No. 10/394,828 filed Mar 21, 2003, now U.S. Pat. No. 7,987,995 B2, the entire contents of which are hereby incorporated by reference. This device separates blood into erythrocyte, plasma and platelet layers and selectively removes the platelet layer as a platelet concentrate, that is, platelets suspended in plasma. The plasma fraction, being in an unconcentrated form, is not effective as a hemostat or tissue adhesive.
SUMMARY OF THE INVENTION
It is an objective of this invention to provide a compact, self-contained system for producing a concentrate of platelets suspended in concentrated fully active plasma, that is substantially unactivated platelets suspended in plasma concentrated by removing water, leaving the fibrinogen in a fully active form.
The PRP separator-concentrator of the present invention is suitable for office use or emergency use for trauma victims.
One embodiment is a disposable self-contained PRP separator and concentrator unit designed for use with a permanent motor assembly.
Another embodiment is a self-contained disposable PRP separator and concentrator that includes an internal motor and power supply assembly.
A still further embodiment comprises a motorized centrifugal separation unit for preparing PRP.
The PRP separator comprises a motorized centrifugal separation assembly for and an optional concentrator assembly for concentrating the PRP. The centrifugal separator assembly comprises a centrifugal drum separator that includes an erythrocyte capture module and a motor with a drive axis connected to the centrifugal drum separator. The concentrator assembly comprises a water-removal system for preparing PRP concentrate.
The centrifugal drum can have an inner wall surface with an upper edge and a lower edge, a drum bottom, and a central axis; the drum bottom can have a central depression and a floor sloping downward from the lower edge to the center of the central depression.
In the portable, self-contained embodiment of the PRP separator-concentrator of this invention, the motorized centrifugal separation assembly includes a motor having a drive axis, the drive axis being coaxial with the central axis. The motor can have the capacity to rotate the centrifugal drum at a speed of at least 2,000 rpm for 120 seconds. The battery can be connected to the motor through an on/off switch or timer switch, the battery having the capacity to provide sufficient power to complete the separation process. The portable centrifugal separator can be fully enclosed within an outer container, the outer container having a top with a sterile syringe port aligned with the central depression, and an access tube connected to and extending downward from the syringe port.
In one embodiment, the erythrocyte capture module is a depth filter lining the inner wall surface of the centrifugal separator unit, the depth filter having pores sized to capture erythrocytes moving into the pores during centrifugal separation of the erythrocytes from blood and to retain the erythrocytes in the depth filter when centrifugal separation is completed. The term “depth filter”, as used herein, is defined as a filter medium that retains contaminants primarily within tortuous passages. It can include an open-cell foam or other matrix made of a material such as a felt that does not significantly activate platelets contacting the surface thereof, whereby erythrocytes moving outward through the plasma during centrifugation move into and are captured by the depth filter leaving behind PRP substantially free from erythrocytes.
In an alternative embodiment of the invention, the inner wall surface of the centrifugal drum can be sloped outwardly from the bottom at an angle of from 1° to 15° with respect to the central axis. The upper edge of the centrifugal drum can be surrounded by an outer, annular erythrocyte capture chamber, the erythrocyte capture chamber including, an outer wall and an inner wall, the outer wall having an upper edge with an elevation higher than the inner wall. The volume of the erythrocyte capture chamber below the top of the inner wall is sized to retain the total volume of separated erythrocytes in the blood while retaining a minimal volume of the PRP. In this embodiment, erythrocytes moving outward through the plasma during centrifugation are retained against the outer wall of the erythrocyte capture chamber and slide downward to substantially fill the lower volume of the erythrocyte capture chamber when centrifugation is ended. During centrifugation, platelets suspended in the liquid in the erythrocyte capture chamber are carried with the flow of plasma displaced by sedimenting erythrocytes so that they travel to the top and over the inner surface of the erythrocyte capture chamber and into the centrifugal drum. Optionally, at least the upper surface of the inner wall of the erythrocyte capture chamber has a slope forming an angle “a” of at least 25° with respect to the central axis for facilitating flow of platelets against the centrifugal force up and over the upper edge of the erythrocyte capture chamber during centrifugation. As the plasma flows from the erythrocyte capture chamber to the centrifugal chamber, the portal or cross-sectional area through which the plasma flows is reduced by the rising slope of the inner wall surface, causing an increase in the plasma flow velocity over the surface and increasing the portion of platelets successfully transported by the plasma.
In one embodiment, the concentrator assembly of the PRP separator-concentrator includes a water-removing hollow fiber cartridge, a pump, and tubing connecting with the hollow fiber cartridge and the pump that circulates PRP in the centrifugal drum through the pump and hollow fiber cartridge and then returns it to the centrifugal drum. In the hollow fiber cartridge, the fibers are ultrafiltration membranes with pores that allow the flow of water through the fiber membrane while excluding the passage of growth factors helpful for healing. The pore structure and surfaces are selected to avoid activation of platelets and disruption of any erythrocytes remaining in the PRP.
In another embodiment, the concentrator assembly includes a plasma concentrating syringe, the syringe having a Luer coupling for connection to the access tube to the center or central depression of the centrifugal drum. In this embodiment, the plasma concentrating syringe comprises a cylindrical barrel with an inner surface and an inlet/outlet port, and a cylindrical actuated piston having an outer surface engaging the inner surface of the barrel. Concentrating beads which can be desiccated hydrogel are positioned between the piston and the inlet/outlet port. A filter is positioned adjacent the inlet/outlet port to prevent escape of the concentrating beads through the inlet/out port. In the operation of the syringe concentrator, movement of the piston in a direction away from the inlet/outlet port draws PRP into the concentrating chamber. Water is removed from the PRP by the concentrating beads, thereby concentrating the PRP without activating the platelets or denaturing the fibrinogen in the plasma. Movement of the piston toward the inlet/outlet port expels concentrated PRP through the inlet/outlet port.
Because the devices of this invention can be operated with standard batteries as their power source, they consume far less power than prior art centrifuge devices, leading to substantial power saving.
A further PRP separator and concentrator embodiment of this invention has a central axis comprises a stationary housing and a rotary assembly mounted for rotation about the central axis with respect to the stationary housing. The rotatable assembly comprises a rotatable centrifugal separator and concentrator and a drive motor. A coupling connects the drive motor and the rotatable assembly, the motor and drive coupling being positioned to rotate the rotatable assembly about the central axis.
The centrifugal separator has an inner separation chamber and an outer erythrocyte capture system. The concentrator comprises a concentration chamber containing desiccated beads. The concentration chamber comprises a floor and a plurality of upright screen supports, the upright screen supports having an inner surface and an outer surface. A cylindrical screen is supported on the outer surface of the upright screen supports.
An axially concentric stationary tube is secured to the housing and extends through the concentration chamber. A stationary bead rake is secured to the tube and extends radially outward. The rake has a distal edge that is positioned adjacent the inner surface of the upright screen supports,
With this assemblage, slow rotation of the rotary assembly with respect to the stationary housing pulls the beads past the stationary rake, reducing gel polarization and clumping of the beads.
Each pair of adjacent upright screen supports can define a desiccating bead receptor for holding desiccated beads radially outward from the distal edge of the rake, whereby bead disruption by the rake during high speed rotational phases is substantially avoided.
The separator and concentrator can include a motor controller, wherein the drive motor has a high rotational speed required for centrifugal separation and PRP collection phases and a slow rotational speed required for water removal by desiccated beads, the motor controller include a switch for initiating high and low rotational speeds of the rotary assembly.
The switch initiates high rotational speed of the rotary assembly during centrifugal and PRP concentrate collection phases and initiates low slow rotational speed of the rotary assembly during the PRP concentrate collection phase.
Another rotatable PRP concentrator of this invention has a stationary housing with a central axis, the concentrator including a drive motor and a coupling connecting the drive motor and the centrifugal separator for rotation about its central axis. The concentrator comprises a concentration chamber containing desiccated beads, the concentration chamber comprising a floor and a plurality of upright screen supports. The upright screen supports have an inner surface and an outer surface. A cylindrical screen is supported on the outer surface of the upright screen supports. An axially concentric stationary tube secured to the housing extends through the concentration chamber. A stationary bead rake is secured to the tube and extends radially outward to adjacent the inner surface of the upright screen supports.
With this configuration, slow rotation of the rotary assembly with respect to the stationary housing pulls the beads past the stationary rake, reducing gel polarization and clumping of the beads.
Each pair of adjacent upright screen supports and the screen segments extending therebetween defines a desiccating bead receptor for holding desiccated beads radially outward from the distal edge of the rake, whereby bead disruption by the rake during high speed rotational phases is substantially avoided.
The separator and concentrator can include a motor controller, wherein the drive motor has a high rotational speed required for the PRP collection phase and a slow rotational speed required for water removal by desiccated beads. The motor controller includes a switch for initiating high and low rotational speeds of the rotary assembly. The switch initiates high rotational speed of the rotary assembly during the PRP concentrate collection phase and initiates low slow rotational speed of the rotary assembly during the PRP concentrate collection phase.
BRIEF DESCRIPTION OF DRAWINGS
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered with the accompanying drawings, wherein:
FIG. 1 is a schematic cross-sectional drawing of a centrifugal separator of this invention with an annular erythrocyte trap.
FIG. 2 is a fragmentary cross-sectional drawing of the centrifugal separator and annular erythrocyte trap portion of the centrifugal separator shown in FIG. 1 .
FIG. 2A is a fragmentary cross-sectional drawing of an alternative erythrocyte trap.
FIG. 2B is a detailed fragmentary view of a vent system according to this invention that uses a sterile porous sheet to allow air movement into and from the outer container.
FIG. 2C is a detailed fragmentary view of a vent system according to this invention that uses a flexible balloon or diaphragm to allow air movement into and from the outer container.
FIG. 3 is a schematic cross-sectional drawing of the separation separator of FIG. 1 after being loaded with blood.
FIG. 4 is a schematic cross-sectional drawing of the separation separator of FIG. 1 during the spin separation phase.
FIG. 5 is a schematic cross-sectional drawing of the separation separator of FIG. 1 after centrifugation has ended.
FIG. 6 is a cross-sectional drawing of a concentrator syringe.
FIG. 7 a schematic cross-sectional drawing of the separation separator of FIG. 1 after PRP has been drawn into a concentrator syringe.
FIG. 8 shows a concentrator syringe containing PRP after the water removal phase with the PRP concentrate ready for use.
FIG. 9 is a schematic cross-sectional drawing of a separation separator of this invention with a depth filter erythrocyte trap.
FIG. 10 is a schematic cross-sectional drawing of the separation separator of FIG. 9 after being loaded with blood.
FIG. 11 is a schematic cross-sectional drawing of the separation separator of FIG. 10 during the spin separation phase.
FIG. 12 is a schematic cross-sectional drawing of the separation separator of FIG. 10 after centrifugation has ended.
FIG. 13 is a schematic cross-sectional drawing of the separation separator of FIG. 9 after PRP has been drawn into a concentrator syringe.
FIG. 14 is a schematic representation of a combination centrifugal separator and hollow fiber concentrator of this invention.
FIG. 15 is a schematic cross-sectional view of a hollow fiber concentrator according to this invention.
FIG. 16 is a cross-sectional view of the hollow fiber concentrator of FIG. 15 , taken along the line 16 - 16 .
FIG. 17 is a schematic cross-sectional view of the membrane valve in the hollow fiber concentrator of FIG. 15 .
FIG. 18 is a schematic cross-sectional drawing of an automated spring-clutch system for preparing PRP concentrate from a patient's blood.
FIG. 19 is an isometric view of a plasma separator and concentrator embodiment of this invention.
FIG. 20 is a top view of the plasma separator and concentrator shown in FIG. 19 .
FIG. 21 is a cross-sectional view of the plasma separator and concentrator of FIG. 20 , taken along the line 21 - 21 , exploded along the vertical axis to show the motor drive and drive receptor relationship prior to placing the disposable separator-concentrator assembly on the drive base.
FIG. 22 is a cross-sectional view of the plasma separator and concentrator of FIG. 20 , taken along the line 22 - 22 .
FIG. 23 is a fragmentary cross-sectional view of the separator-concentrator shown in FIG. 22 .
FIG. 24 is a cross-sectional drawing of the device of FIGS. 19-23 after blood has been added.
FIG. 25 is a cross-sectional drawing of the device of FIGS. 19-23 during the centrifugal separation stage producing PRP.
FIG. 26 is a cross-sectional drawing of the device of FIGS. 19-23 during the slow rotation concentration stage.
FIG. 27 is a cross-sectional drawing of the device of FIGS. 19-23 during the centrifugal PRP concentrate separation stage.
FIG. 28 is a cross-sectional view of a portable embodiment of this invention.
DETAILED DESCRIPTION OF THE INVENTION
This device and method separates plasma-rich plasma from blood and removes water from the plasma-rich plasma without denaturing the fibrinogen or activating the platelets invention. One aspect of the invention is a portable, completely self-contained device that performs this method with a patient's blood to provide an autologous product that is useful as wound healing tissue sealant and adhesive that promotes and speeds healing. Another aspect of the invention is a portable disposable system that can be used with a permanent motorized unit to provide this method and product. A still further aspect is a portable disposable system for producing PRP from a patient's blood.
The devices of this invention are small, portable, self-contained, disposable PRP separation systems. The centrifugal separation modules described with respect to FIGS. 1-13 are one aspect of this invention. They are directed to disposable PRP separation systems that can be used by a medical assistant or doctor without extensive training to prepare PRP and a PRP concentrate from a patient's blood within minutes, with a high recovery of platelets and without significant activation of the platelets. The devices are completely automated and require no user intervention between, first, loading and actuating the device and, second, retrieving the PRP. The devices are able to process bloods of different hematocrits and different plasma densities.
Another more highly automated separator-concentrator of this invention is the combination centrifugal separator and hollow fiber cartridge concentrator shown in FIG. 14 . This system requires no user intervention between loading the blood and retrieving PRP concentrate.
FIG. 1 is a schematic cross-sectional drawing of a centrifugal separator of this invention with an annular erythrocyte trap, and FIG. 2 is a fragmentary cross-sectional drawing of the centrifugal separator and annular erythrocyte trap shown in FIG. 1 . Referring to FIGS. 1 and 2 , the separation system comprises a centrifugal separator unit or chamber 2 and a motor 4 . The centrifugal separator unit comprises a centrifugal drum 5 having an inner wall surface 6 with an upper edge 8 and a lower edge 10 , a drum bottom 12 , and a central axis (not shown). The drum bottom 12 has a central depression 14 , the bottom 12 constituting a floor sloping downward from the lower edge 10 to the central depression 14 . The motor 4 has a drive axis 16 that is coaxial with the central axis. The motor 4 has the capacity to rotate the centrifugal drum at a speed of at least 2,000 rpm for 120 seconds.
The complete, self-contained unit includes a battery 18 connected to the motor 4 through conventional power connections, the battery 18 having sufficient capacity to complete the separation process. The battery 18 is connected to the motor through an on/off time switch 20 with a manual knob 22 .
An outer container 24 encloses the centrifugal separation unit. The container 24 has a top 26 with a sterile syringe port 28 that can be a Luer fitting aligned with the central depression 14 . An access tube 29 connects to and extends downward from the syringe port 28 into the separation chamber 2 . Tube 29 is used for introducing blood into the separation chamber 2 and for removing PRP from the separation chamber 2 as is explained in greater detail with respect to FIGS. 2-6 hereinafter.
The inner wall surface 6 of the centrifugal drum 5 is sloped outwardly from the bottom 12 at an angle of from 75 to 89° from the central axis. The upper edge 8 of the centrifugal drum 5 is surrounded by an outer, annular erythrocyte capture chamber 31 .
Preferably, the outer container 24 for the system is sealed to maintain sterility. To prevent pressure fluctuations from movement of liquid into and from the system, a vent system 30 is provided in a wall of the outer container that permits movement of air out of the container when liquid is introduced and movement of air into the container when liquid is removed. Details of suitable venting systems are described hereinafter with respect to FIGS. 2B and 2C .
Referring to FIG. 2 , the erythrocyte capture chamber 31 includes an outer wall 32 , and an inner wall 34 , the outer wall 32 having a top edge 36 with an elevation higher than the top 8 of the inner wall 6 . The vertical distance between the top edge and the top of the inner wall is small, preferably less than 1 mm, but large enough to allow passage of cells, preferably greater than 50 microns. The narrow gap between the top of the inner wall and the top of the chamber serves to minimize the sweeping of erythrocytes from the erythrocyte capture chamber into the centrifugal drum by the swirling wave of PRP during deceleration after completion of the centrifugation step. To further minimize sweeping of erythrocytes back into the centrifuge drum during deceleration, the gap above the inner wall can be filled with a depth filter or screen. The volume of the erythrocyte capture chamber 31 is sized to retain the total volume of separated erythrocytes and leukocytes in the blood while retaining a minimal volume of PRP. An annular cap 38 is secured to the top of the centrifugal drum 5 and the erythrocyte capture chamber 31 in a sealing engagement that prevents escape of blood and blood products from the centrifugal chamber during the centrifugal separation step.
The upper surface portion 42 of the inner wall 34 of the erythrocyte capture chamber 31 can optionally have a slope forming an angle “a” at least 25° with the central axis, facilitating flow of platelets in the PRP flowing inwardly over the upper edge 8 of the erythrocyte capture chamber 31 when the erythrocytes sediment to fill the erythrocyte capture chamber 31 .
FIG. 1 shows the separation system coupled with a syringe 44 positioned to introduce blood into the separation chamber 2 . The syringe 44 is shown with the plunger or piston 46 in the extended, full position prior to the blood introduction.
FIG. 2A is a fragmentary cross-sectional drawing of an alternative erythrocyte trap configuration. In this alternative embodiment, the upper surface portion 42 of the erythrocyte capture chamber 31 shown in FIG. 2 extends as surface 43 downward to the opposing wall 45 , providing a continuous sloped surface for movement of platelets to the centrifugal chamber 5 during centrifugation. Surface 43 forms the angle “a” with the central axis (not shown) of the erythrocyte capture chamber.
FIG. 2B is a detailed fragmentary view of a vent system 30 a according to this invention that uses a sterile porous sheet to allow air movement into and from the outer container. In this embodiment, an air flow passageway 50 in a wall 52 of the outer container 24 ( FIGS. 1 and 2 ) is sealed with a conventional sterile porous sheet 54 . The sterile porous sheet 54 that has sufficient porosity to allow free movement of air through the sheet, but is an effective microorganism barrier that prevents movement of microorganisms from the outer environment into the container 24 . This prevents significant fluctuations of air pressure in the outer container 24 during liquid movement into and out of the system.
FIG. 2C is a detailed fragmentary view of a vent system 30 b according to this invention that uses a flexible balloon or diaphragm to allow air movement into and out of the outer container 24 . In this embodiment, an air flow passageway 56 in the wall 52 of the outer container 24 ( FIGS. 1 and 2 ) is sealed with a balloon or flexible diaphragm 60 . The balloon or flexible diaphragm 60 should have sufficient flexibility and size to allow free movement of air through the air flow passageway 56 in a volume that can be at least equal to the total volume of blood that is introduced into the system during the separation process. This prevents significant fluctuations of air pressure in the outer container 24 during liquid movement into and out of the system. The balloon or flexible diaphragm 60 must have the integrity to be an effective microorganism barrier preventing movement of microorganisms from the outer environment into the container 24 during PRP removal.
FIGS. 3-5 show successive stages in the preparation of PRP with the device of FIG. 1 . FIG. 3 is a schematic cross-sectional drawing of the centrifugal separator of FIG. 1 after being loaded with blood 62 from syringe 44 . Syringe 44 is attached through the Luer port 28 and communicates with the access tube 29 , and the plunger 46 has been depressed to expel the blood contents of the syringe into the separation chamber 2 .
FIG. 4 is a schematic cross-sectional drawing of the centrifugal separator of FIG. 1 during the spin separation phase. During this phase, the syringe 44 can be removed as shown, to be replaced with a sterile cap or a fresh syringe to remove separated PRP product. Alternatively, the syringe 44 can be left in place during the separation phase (not shown) and reused to remove the PRP product. During the spin phase, the centrifugal force causes the more dense erythrocytes 64 to move outward through the plasma until they collect in the erythrocyte capture chamber, leaving PRP 66 in the centrifugal drum 5 .
FIG. 5 is a schematic cross-sectional drawing of the centrifugal separator of FIG. 1 after centrifugation has ended. When centrifugation is complete and the centrifugal forces are no longer present, the dense erythrocyte layer remains isolated in the erythrocyte capture chamber 31 , and the layer of PRP 66 in the centrifugal drum collects at the lowermost section of the centrifugal chamber. The PRP can then be removed through the access tube 29 from the centrifugal drum 5 with the original syringe 44 ( FIG. 3 ) or a fresh syringe positioned as shown in FIG. 3 .
If one desires to obtain a PRP concentrate according to this invention, one can use the concentrating syringe shown in FIG. 6 wherein FIG. 6 is a cross-sectional schematic view of a syringe embodiment for producing PRP concentrate from PRP. The syringe device 69 includes a process chamber 70 having an outer wall 72 . In the process chamber 70 , a plunger 74 is positioned above filter 76 , the plunger 74 and the filter 76 defining a concentrating portion or chamber 78 of the process chamber 70 . The concentrator chamber 78 contains concentrating desiccated hydrogel beads 80 and one or more agitators 82 . A concentrate chamber 84 , positioned below or downstream of filter 76 , includes an inlet/outlet port 86 .
The concentrating desiccated hydrogel beads 80 can be insoluble beads or disks that will absorb a substantial volume of water and not introduce any undesirable contaminant into the plasma. They can be dextranomer or acrylamide beads that are commercially available (Debrisan from Pharmacia and BIO-GEL P™ from Bio-Rad Laboratories, respectively). Alternatively, other concentrators can be used, such as SEPHADEX™ moisture or water absorbents (available from Pharmacia), silica gel, zeolites, cross-linked agarose, etc., in the form of insoluble inert beads.
The agitators 82 can be dense objects such as inert metal spheres. It will be readily apparent to a person skilled in the art that the shape, composition and density of the agitators 82 can vary widely without departing from the invention so long as the agitator has a density substantially greater than whole blood. It is advantageous that the agitator be a metal sphere such as a titanium or stainless steel sphere that will not react with blood components, or a dense sphere coated with an inert coating that will not react with blood components.
The filter 76 can be any inert mesh or porous materials which will permit the passage of plasma and prevent passage of the hydrogel beads and agitator. The filter can be a metal wire or inert fiber frit of either woven or non-woven composition, or any other frit construction which, when the liquid in the concentration chamber is passed through the filter, will permit passage of the PRP and not the hydrogel beads and agitator, effectively separating the PRP from the hydrogel beads and agitators as will be described in greater detail hereinafter.
It is important that the water removal procedure be carried out with minimal activation of the platelets and minimal denaturation of the fibrinogen. Prior art commercial procedures for preparing plasma concentrate use precipitation to separate fibrinogen from albumin and reconstitution to prepare the sealant. This deactivates a major portion of the fibrinogen and removes healing factors. As a result proportionally more of the reconstituted precipitate is required to achieve effective tissue sealing. With the device of this invention, denaturing of the fibrinogen is avoided by water removal and the healing factors in the plasma are retained with the fibrinogen during the concentration step, yielding a more effective tissue sealant and adhesive that also promotes healing.
FIGS. 7 and 8 show the preparation of PRP concentrate using the syringe concentrator shown in FIG. 6 . FIG. 7 is a schematic cross-sectional drawing of the centrifugal separator of FIG. 5 after PRP 66 has been drawn into a concentrator syringe, and FIG. 8 shows a concentrator syringe containing PRP concentrate 90 after the water removal phase. Moving plunger or piston 74 draws PRP 66 from the centrifugal drum 5 into the syringe chamber. A volume of air is also drawn into the syringe to facilitate expulsion of PRP concentrate after concentration.
The concentrator syringe is then withdrawn from the centrifugal separator and shaken by a reciprocal movement in the direction of the syringe axis. This movement causes relative agitating movement of the agitator balls 82 in the PRP 66 , stirring the hydrogel beads in the solution, and mixing the PRP to reduce localized concentrations and gel polarization of plasma proteins around the bead surfaces, thereby facilitating movement of water from the PRP into the beads 80 . FIG. 8 shows the concentrator syringe with the PRP concentrate 90 after the water removal step is completed. Movement of the plunger 74 toward the inlet-outlet port 86 discharges PRP concentrate 90 through the applicator needle 92 , the filter 76 preventing movement of the hydrated beads 94 and agitator 82 with the PRP concentrate. Concentrated PRP retained within the interstitial space between beads is purged by air as the plunger is depressed further.
FIG. 9 is a schematic cross-sectional drawing of a centrifugal separator of this invention with a depth filter erythrocyte trap. This embodiment also comprises a centrifugal separator unit 102 and a motor 104 . The centrifugal separator unit comprises a centrifugal drum 106 having an inner wall surface 108 with a bottom edge 110 , a drum bottom 112 , and a central axis (not shown). The drum bottom 112 has a central depression 114 , the bottom 112 constituting a floor sloping downward from the lower edge 110 to the central depression 114 . The motor 104 has a drive axis 116 coaxial with the central axis. The motor 104 has the capacity to rotate the centrifugal drum 102 at a speed of at least 2,000 rpm for 120 seconds with a total power consumption of less than 500 mAh, the power that is obtainable from a small battery such as a conventional 9 volt alkaline battery.
The complete, self-contained unit includes a battery 118 connected to the motor 104 through conventional power connections. The battery 118 has the capacity to provide sufficient power to complete the separation process and being connected to the motor through an on/off toggle or timer switch 120 with a manual knob 122 .
An outer container 124 encloses the centrifugal separation unit. The container 124 has a top 126 with a sterile syringe port 128 aligned with the central depression 114 , an access tube 130 connected to and extending downward from the syringe port 128 for introducing blood into the separation chamber 132 and for removing PRP from the separation chamber 132 as is explained in greater detail with respect to FIGS. 10-13 hereinafter.
The inner wall 108 of the centrifugal separator unit 102 is the surface of a depth filter 134 having pores sized to capture erythrocytes moving into the pores during centrifugal separation of the erythrocytes from blood and to retain the erythrocytes in the material of the depth filter when centrifugal separation is completed, the material of the depth filter being selected from a material that does not significantly activate platelets contacting the surface thereof.
The depth filter 134 can be a honeycomb-like or woven fiber material that allows fluids and small particles to flow freely (e.g., felt or open cell polyurethane foam). Like a wetted sponge, the depth filter holds liquid against a certain head of pressure due to surface tension forces. Thus, blood cells or other suspended particulates remain entrapped within the foam when the centrifuge stops and separated platelet-rich plasma drains from the surface under the force of gravity. Foam can be either rigid or flexible and can be formed into the appropriate annular shape for the device by molding or die-cutting. The parts are sized so that the packed cell (e.g., erythrocyte and leukocyte) layer is fully contained within the outer depth filter chamber, which retains the cells when the centrifuge stops.
With this device, erythrocytes moving outward through the plasma during centrifugation pass into and are captured by the depth filter 134 , and the PRP flowing downward when centrifugation is ended is substantially free from erythrocytes as is described hereinafter in greater detail with respect to FIGS. 10-13 .
Similar to the vent system provided in the system shown in FIGS. 1 and 2 , a vent system 136 can be provided in the outer container 124 . This vent system can be the same as described hereinabove with respect to FIGS. 2B and 2C .
FIG. 10 is a schematic cross-sectional drawing of the centrifugal separator of FIG. 9 after being loaded with blood 138 from syringe 140 , the syringe connecting through the sterile seal 128 and into the vertical tube 130 , and the plunger 142 having been depressed to expel the blood contents of the syringe into the separation chamber 132 .
FIG. 11 is a schematic cross-sectional drawing of the centrifugal separator of FIG. 10 during the spin separation phase. During this phase, the syringe 140 can be removed as shown to be replaced with a sterile cap or fresh syringe to remove the separated PRP product. Alternatively, the syringe 140 can be left in place (not shown) during the separation phase and used to remove the PRP product. During the spin phase, the centrifugal force causes the more dense erythrocytes to move outward through the plasma into the depth filter 134 , leaving PRP 148 substantially free from erythrocytes in the centrifugal drum 102 .
FIG. 12 is a schematic cross-sectional drawing of the centrifugal separator of FIG. 11 after centrifugation has ended. When centrifugation is complete and the centrifugal forces are no longer present, the erythrocyte-free PRP product 148 flows downward in the separator chamber 132 , the erythrocytes remaining trapped in the depth filter 134 . The PRP 148 that collects in the centrifugal drum 102 is substantially free from erythrocytes and leukocytes. The PRP 148 can then be removed from the centrifugal drum 102 with the original syringe 140 ( FIG. 10 ) or a fresh syringe as will be readily apparent to a person skilled in the art.
FIG. 13 is a schematic cross-sectional drawing of the centrifugal separator of FIG. 12 after PRP 148 has been drawn into a concentrator syringe 69 . Withdrawing the plunger or piston 74 draws PRP 148 from the centrifugal chamber 132 into the syringe barrel 150 .
The water is removed from the PRP 148 to produce a PRP concentrate and expelled from the syringe as is described hereinabove with respect to FIGS. 7 and 8 .
FIG. 14 is a schematic representation of a combination centrifugal separator and hollow fiber concentrator of this invention. The entire separation and concentration components are enclosed in a housing 160 . The top of the housing has a sterile vent 162 to allow passage of air displaced during addition and removal of fluid from the device and a Luer fitting 164 to which a standard syringe 166 with a piston 168 and piston actuator 170 can be coupled.
A centrifugal separator 172 can have the annular erythrocyte trapping system shown and described hereinabove with respect to FIGS. 1-5 or it can have the depth filter erythrocyte trapping system shown and described hereinabove with respect to FIGS. 9-13 .
A drive motor 174 is positioned in the bottom section of the housing 160 below the centrifugal separator 172 in the basic configurations shown in FIGS. 1 and 9 .
Positioning the hollow fiber concentrator system 176 above the centrifugal separator 172 simplifies the liquid transfer components of the concentrator, although it will be readily apparent to a person skilled in the art that alternative configurations such as side-by-side placement or placing the centrifuge above the concentrator are also suitable, provided adequate space is provided to house the fluid transfer tubing.
The concentrator system comprises a hollow fiber cartridge 178 and a pump 180 .
A central tube 182 having outlet 184 extends from the Luer fitting 164 toward the depression 186 at the bottom of the centrifugal separator 172 . A inlet flow check valve 188 limiting liquid flow toward the centrifugal separator is placed in the central tube 182 at an intermediate level
The tube outlet 184 is positioned to circulate PRP, preferably stopping short of the bottom 186 .
A return tube 190 extends from the bottom depression 186 to a pump inlet check valve 192 communicating with the inlet of pump 180 . Check valve 192 directs liquid movement in the direction toward the pump, thus preventing backflow into line 190 . A second return tube, but also referred to as a line or conduit, 194 extends from pump outlet check valve 196 communicating with the outlet of pump 180 . Check valve 196 directs liquid movement in the direction leading away from the pump, thus preventing backflow from line 194 to the pump. Second return tube 194 extends to the inlet manifold 198 of the hollow fiber cartridge concentrator 178 . A third return tube 200 extends from the outlet manifold 202 of the hollow fiber cartridge 178 to a concentrator outlet check valve 204 leading to the central tube 182 at a position above (or upstream of) check valve 188 . Tube 200 is sized to restrict the flow of fluid, generating a backpressure upstream in the fluid circulation path to drive filtration through the hollow fiber membranes. Check valve 204 prevents backflow of liquid from the tube 182 to the hollow fiber cartridge 178 .
The hollow fiber cartridge includes fiber membranes that efficiently remove water and salts from the plasma while leaving larger healing factors. Choice of the fiber materials and pore distributions is a critical factor because rapid water removal without significant platelet damage must be achieved. The large concentration of protein present in plasma presents another difficulty since it thickens along the membrane surface due to localized concentration and gel polarization. Therefore, the fiber membranes and their configuration must facilitate sweeping of the membrane surface by passing plasma, disrupting the polarization and redistributing the plasma constituents. Furthermore, because a preferred embodiment of this device is intended to be self-contained and highly portable, it is preferred that the hollow fiber cartridge provide its ultrafiltration function with minimal energy consumption so that complete separation and concentration can be achieved with a standard small (e.g., 9 volt transistor) battery.
The pump 180 can be a conventional piston or diaphragm pump that provides the necessary circulation of plasma through the hollow fiber concentrator system 176 without use of excessive energy. Preferably, the pump 180 should have the capacity to complete concentration of the plasma with a power consumption of less than 500 mAh, that is, the power available from a small battery such as a standard 9 volt alkaline battery.
Power to the motor 174 and pump 180 is provided by conventional wiring and a small battery (not shown) that has the capacity to provide sufficient power to complete the concentration process. A small (e.g., standard 9 V transistor radio) battery is acceptable. Alternatively, if the unit is to be used in a location with standard auxiliary power, a conventional power supply system using standard business and residential power can be used.
The system shown in FIG. 14 operates as follows: Blood is provided to separator Luer fitting by a blood-filled syringe, using syringe such as syringe 166 . Downward movement of the actuator 170 moves the piston 168 in a downward direction, expelling the contents of the syringe through the Luer fitting 164 and the tubing 182 through the inlet check valve 188 into the bottom of the centrifugal separator 172 . After its contents have been expelled, the syringe can be left in place or replaced with a fresh syringe or sealing cap to prevent fluid from escaping through the Luer port 164 during the concentrating step of the process.
Operation of the centrifugal separator 172 removes erythrocytes and leukocytes from the blood, leaving PRP in the bottom of the centrifuge chamber after centrifugation is stopped.
Operation of the pump 180 draws PRP from the lower depression 186 of the centrifugal separator upward through tube 190 , through the pump inlet check valve 192 into the pumping chamber (not shown) of the pump 180 . Then PRP flows through pump 180 and through pump outlet check valve 196 . From check valve 196 , the PRP passes through the tubing 194 into the inlet manifold 198 of the hollow fiber concentrator 178 and through the hollow fiber concentrator.
PRP from which a portion of the water and salts have been removed then flows from the outlet manifold 202 of the hollow fiber concentrator 178 through flow restrictive tubing 200 and concentrator outlet check valve 204 to the inlet tubing 182 , and then through check valve 188 to the bottom of the centrifugal separator 172 where it mixes with the other PRP. This cycling process is continued, removing a portion of the water in each pass, until the desired concentration of PRP has been obtained.
With the device of this invention PRP erythrocyte removal and concentration of the PRP to a platelet concentration of 3× can be automatically achieved within 5 minutes. If higher PRP concentration is needed for a particular application such as for sealing tissues to stop bleeding, the concentration cycle can be continued beyond 5 minutes, whereby concentration up to 5× and higher can be achieved.
FIG. 15 is a schematic cross-sectional view of a hollow fiber concentrator shown in FIG. 14 , and FIG. 16 is a cross-sectional view of the hollow fiber concentrator of FIG. 15 , taken along the line 16 - 16 .
Referring to FIG. 15 , the hollow fiber concentrator 178 is combined with an extracted liquid reservoir 206 . The concentrator 178 has an outer housing 208 that encloses the inlet manifold 198 , an outlet manifold 202 , a plurality of hollow ultrafiltration fibers 210 and an extracted liquid chamber 212 . Each of the hollow fibers 210 has a wall 214 , an axial passageway 216 , an inlet end 218 and an outlet end 220 . The inlet end 218 of each hollow fiber 210 is secured to a correspondingly sized hole in the inlet manifold plate 222 in a conventional manner that establishes communication between the hollow fiber passageway 216 and the inlet manifold 198 while preventing escape of the liquid contents thereof into the extracted liquid chamber 212 . The outlet end 220 of each hollow fiber 210 is secured to a correspondingly sized hole in the outlet manifold plate 226 in a conventional manner that establishes communication between the hollow fiber passageway 216 and the outlet manifold 202 while preventing escape of the liquid contents thereof into the extracted liquid chamber 212 .
Referring to FIGS. 15 and 16 , the extracted liquid chamber 212 is the space defined by the inner wall surface 213 of the housing 208 , the outer wall surface of the hollow fibers 210 , and the manifold plates 222 and 226 . The extracted liquid chamber 212 captures the liquid that passes through the hollow fibers 210 in the ultrafiltration process.
The outlet end of conduit 194 shown in FIG. 14 connects with the inlet manifold 232 through manifold inlet conduit 230 . The inlet end of conduit 200 shown in FIG. 14 connects with the outlet manifold 202 through manifold outlet conduit 228 .
During the water removal process, pressurized plasma passes from conduit 194 through the inlet manifold inlet conduit 230 into the inlet manifold 198 , and then through the hollow fibers 210 . In each pass a portion of the water and salts passes through the pores in the fiber walls into the extracted liquid chamber 212 . The concentrated plasma then passes into the outlet manifold 202 , through the outlet manifold outlet conduit 228 and then to the conduit 200 .
The extracted liquid reservoir 206 has a reservoir housing 234 that connects with an overflow conduit 236 . The overflow reservoir 206 has an air vent 238 .
FIG. 17 is a schematic cross-sectional view of the membrane valve air vent 238 in the hollow fiber concentrator of FIG. 15 . The valve 238 comprises a porous lower hydrophilic membrane 240 communicating with the interior of the extracted liquid reservoir 206 and a porous upper hydrophobic membrane 242 that communicates with outer space surrounding the reservoir. The extracted liquid reservoir captures extracted liquid when the volume of the extracted liquid exceeds the volume of the extracted liquid chamber 213 and the excess liquid escapes through the extracted liquid conduit 236 into the extracted liquid chamber 206 . Air in the extracted liquid chamber displaced by the incoming liquid escapes through the porous membranes 240 and 242 until the liquid level reaches the membranes, saturating the hydrophilic membrane 140 . Escape of the extracted liquid from the extracted liquid chamber 206 is prevented by the hydrophobic membrane 242 .
The valve prevents movement of air into the system when PRP concentrate is removed as follows. Movement of PRP concentrate from the centrifugal separator 172 ( FIG. 14 ) creates a partial vacuum in the system. Movement of air through the valve 238 in response to this partial vacuum is prevented by the liquid saturated hydrophilic membrane 240 .
FIG. 18 is a schematic cross-sectional drawing of an automated spring-clutch system for preparing PRP concentrate from a patient's blood. Like other embodiments of this invention, the disposable, single-use system is enclosed in a compact portable device that can be smaller than a twelve ounce soft drink can.
Referring to FIG. 18 , the outer housing 252 is sealed except for the blood inlet port 254 , the PRP concentrate withdrawal port 256 , and sterile vent 258 . The PRP withdrawal port 256 is one end of a rigid PRP concentrate withdrawal tube 260 that is secured to the outer housing 252 and functions as a central axle around which the rotary separation components turn and also as a PRP concentrate withdrawal tube. The separation components comprise a upper rotary centrifugal separator housing 262 and a lower rotary water removal system housing 264 , these two housing being connected by an integral cylindrical waist element 266 into a unitary housing structure. The water removal system housing 264 includes a PRP concentrate reservoir 268 that communicates with the lower opening 270 of the PRP concentrate withdrawal tube 260 .
The rotary components are supported on the drive axle 272 of the two direction, two speed motor 274 . The direction and speed of the motor 274 are controlled by the conventional motor controller 276 to which it is connected by electrical conduit 278 . Switch 280 activates the motor controller 276 .
The relative position of the rotary components in the outer housing 252 is maintained by a roller bearing raceway structure. This structure that includes a plurality of roller bearings 282 positioned between an outer ring flange 284 secured to the outer housing 252 and an inner ring flange 286 secured to the upper rotary centrifugal separator housing 262 .
The centrifugal blood separating components housed in the upper housing 262 of the rotary assemblage is similar in structure and function to other blood separators described hereinabove with respect to FIGS. 9-13 in that the cylindrical rotary centrifugal separator 290 has the inner surface of its outer wall lined with a cylindrical depth filter 294 . A blood overflow reservoir 296 , defined by a floor 298 and an integral wall 300 , can function to control or limit the volume of blood that is subject to the separating operation. The overflow reservoir 296 can assist if the volume introduced exceeds the volume that can be effectively concentrated in the water removal operation, described in greater detail hereinafter. When the centrifugal separator spins during the separation phase, excess blood flows upwardly along the wall 300 and into the [[PRP]] reservoir 296 . When the separation phase ends and the rotary speed slows, the wall 300 prevents escape of liquid as it settles on the floor 298 .
Suitable depth filter materials have been described hereinabove with respect to FIGS. 9-13 . Alternatively, the depth filter structure 294 and overflow reservoir structure 296 can be replaced with an erythrocyte trap and function such as is described with respect to FIGS. 1-8 hereinabove in a manner that would be readily apparent to a person skilled in the art.
During the centrifugal separation stage, erythrocytes separating from the plasma flow into the depth filter 294 , leaving a layer of PRP behind outside the depth filter.
When the centrifugal separation is completed and centrifugal separation is ended, the PRP flows to the bottom of the centrifugal separator where it is held by the seal of the valve plate 302 against the floor 304 of the separation housing.
The seal of the valve plate 302 against the floor 304 is opened by action of a spring clutch assembly. The valve plate 302 is a part of a valve assembly including a hollow upper valve stem 306 (a cylinder) integral with the plate 302 through which the rigid tube 260 extends. This stabilizes orientation of the valve assembly on the rigid tube 260 . The lower part of the valve assembly is outer cylinder 308 with internal threads 310 .
The outer cylinder 308 further encloses an inner cylinder 312 that has external threads 314 engaging the internal threads 310 of the outer cylinder 308 in sliding engagement. The spring clutch 288 wraps around the rigid tube 260 and is positioned between the inner cylinder 312 to which it is secured and the rigid tube 260 . The spring clutch 288 functions as a slip bearing between the rotating internal threaded element 312 and the rigid tube 260 during the centrifugal separation phase because the direction of the movement of the spring around the rigid tube 260 tends to open the spring, reducing then sliding friction.
After the centrifugal separation of the PRP is completed, the motor 274 is then activated to turn slowly in a reverse direction. The spring-clutch 288 rotates around the rigid tube 260 in a direction that tightens the spring, locking the spring to the rigid tube 260 . As the outer cylinder 308 turns around the locked stationary inner cylinder 312 , the outer cylinder 308 rises, lifting unseating the valve plate 306 , the movement continuing until the top surface 316 of the upper valve stem 306 abuts the collar 318 secured to the rigid tube 260 .
When the valve plate 302 unseats, the PRP in the bottom of the centrifugal separator 290 flows downward through a channel 320 defined by the outer surface 322 of the lower cylinder and the inner surface 324 of the waist cylinder 266 into the lower rotary water removal system enclosed in the lower housing 264 where it contacts the desiccated gel beads 326 . Direct flow of liquid from the water removal system is prevented by O-ring seal 327 .
The lower rotary water removal system 328 enclosed in lower housing 264 comprises a rotary cylindrical screen element 330 which has radially inwardly extending comb elements 332 and a rake system. The bottom of the lower housing 264 has a central opening with a downwardly extending cylindrical flange 333 to accommodate the rigid tube 260 . O-ring 327 is positioned between flange 333 and the rigid tube 260 to prevent liquid flow therebetween. The rake system comprises a rake cylinder 334 having radially outward extending rake elements 336 that mesh with the comb elements 332 . The rake cylinder 334 is separated from the rigid tube 260 by roller bearings 338 that reduce friction between the rake cylinder 334 and the tube 260 during the high speed rotation of the centrifugation step. The rake cylinder has a projecting spline 340 that engages a matching vertical recess grove (now shown) in the lower valve stem outer cylinder 308 . The spline 340 is positioned to move up and down in the matching grove to maintain engagement of the rake cylinder 334 and the lower valve stem outer cylinder 308 at all elevations of the valve stem. The spline system locks the rake cylinder 334 to the stationary tube 260 when the spring clutch engages, preventing rotation of the rake cylinder when the comb elements are rotated through the rakes.
As water is removed from the PRP by the desiccated beads 326 , gel polarization occurs, slowing water absorption into the beads. To reverse this effect, the beads are slowly stirred during the dewatering process from slow rotation of the cylindrical screen and rake elements by the motor 274 . The relative movement of the rake 336 through the gel beads 326 and through the spaces of the comb 320 stirs the beads and breaks up bead clumps, increasing efficiency of the water removal process. This process is obtained as follows.
When water removal is completed, the motor controller 276 can reverse rotational direction of the drive shaft 272 , causing disengagement of the spring clutch 288 from the rigid tube 260 , and permitting the separation assembly elements to rapidly spin as a unit. During this spin, the concentrated PRP is spun from the beads 270 through the cylindrical screen 330 where it is collected in the PRP concentrate reservoir 268 . PRP concentrate is then drawn from the PRP concentrate reservoir 268 though the rigid tube 260 and out through the PRP concentrate withdrawal port 256 .
FIG. 19 is an isometric view of a plasma separator and concentrator embodiment of this invention; and FIG. 20 is a top view of the plasma separator and concentrator shown in FIG. 19 . This embodiment comprises a disposable separator/concentrator module 350 and a permanent base 352 with the motor and control system. The separator/concentrator module 350 has a housing 354 and a housing top 356 . The housing top 356 has a blood inlet port 358 and a plasma concentrate outlet port 360 . The base 352 has a base housing 362 with a control switch 364 and an external power connector 366 ( FIG. 20 ). This compact unit separates platelet rich plasma (PRP) from blood and removes water from the PRP to form an autologous platelet rich plasma concentrate from a patients blood within minutes.
FIG. 21 is a cross-sectional view of the plasma separator and concentrator of FIG. 20 , taken along the line 21 - 21 , separated along the vertical axis to show the motor drive and drive receptor relationship prior to placing the disposable separator-concentrator assembly on the drive base. The drive base 368 comprises a base housing 370 supported on a plurality of base feet 372 . The housing has a rotary assembly guide surface 374 that is shaped to match the shape of the base receptor 376 of the separator and concentrator assembly 350 . It has an annular support surface 380 that together with the top support surface 382 supports and aligns the separator and concentrator assembly 350 on the base 368 . In the base 368 , a motor 384 is mounted on a support plate 386 that is held in position by a plurality of support fixtures 388 . The motor 384 has a drive connector 390 that securely mates with the rotary assembly drive receptor 392 . The base has a conventional power connector 366 and a conventional motor control switch 364 that are electrically connected to the motor with conductors in a conventional manner (not shown). The motor control switch 364 includes a conventional timer that controls the motor speed at different phases of the separation and concentration process as is described in greater detail hereinafter.
The rotary unit comprises the housing 354 with the housing top 356 supporting the PRP concentrate outlet port 360 . The housing 354 includes a base 394 with a base receptor 376 that is shaped and sized to mate with the top support surface 374 and assembly guide to support and align the separator and concentrator assembly 350 on the base 374 . Axially concentric bearing assembly 396 is positioned to support the separator and concentrator assembly 350 in position to permit mating of the drive connector 390 and the drive receptor 392 . The drive connector 390 and drive receptor 392 have matching shapes that require the two units to turn a single unit. They can have any cross-sectional shape that prevents the drive connector 390 from turning inside the drive receptor 392 such as the rectangular shape shown. It can also have any other polygonal or oval shape that provides this result. Circular cross-sections are also acceptable if they are keyed in a conventional manner fully within the skill of the art, and all functionally equivalent shapes are intended to be within the scope of this invention.
The separation and concentration assembly 378 rotates about the vertical axes established by the stationary fixed tube 398 . Tube 398 also constitutes a PRP concentrate conduit. This communicates with the PRP concentrate outlet 360 . Tube 398 is rigidly secured against rotation about its central axis by its connection with the top 356 of the outer housing 354 . The lower end 398 of the tube 398 includes a PRP concentrate inlet 400 and a rake hub 402 that is rigidly connected to the tube so that it remains stationary when the rotary components are in motion as will be described in greater detail hereinafter.
The separation and concentration assembly 378 includes a rotary housing 378 , the tapered bottom 404 of which includes the drive receptor 392 . The separation and concentration assembly 378 has a top plate 406 with a sterile vent 408 that is supported in its position on the tube 398 by sleeve bearing 410 .
The desiccated gel beads used to removed water from the PRP are omitted from FIGS. 21-23 to present more clearly the other components of the concentrating assembly. They are shown in FIGS. 24-27 .
The separation and concentration assembly 378 has an outer wall 412 that isolates the blood components during the separation and concentrating process. The upper portion of the housing 378 encloses a centrifugal plasma separator that comprises a cylindrical blood reservoir 416 with an outwardly tapering inner surface 418 and an inner wall 420 that surrounds the tube 398 and is configured to permit free rotation of the inner wall 420 around the tube 398 . This combination maintains axial orientation of the blood reservoir during centrifugal motion of the separation process. Surrounding the blood reservoir 416 is a cylindrical depth filter 424 above which is positioned an annular blood overflow reservoir 426 , details and functions of which are described in greater detail hereinbelow with respect to FIG. 23 .
A concentrator assembly 428 is positioned below the blood reservoir 416 and depth filter 424 . The concentration assembly comprises a concentrating basket 429 formed by an axially concentric rotary screen 430 and a concentrator base 432 . The screen has a cylindrical cross-section and is supported by a circular array of vertical supports 434 . Surrounding the screen 430 is a concentric PRP concentrate reservoir comprising a vertical side wall 438 and the tapered bottom 404 . The center of the tapered bottom 404 is positioned adjacent the inlet opening 400 of the tube 398 .
FIG. 22 is a cross-sectional view of the plasma separator and concentrator of FIG. 20 , taken along the line 22 - 22 and should be considered together with FIGS. 21 and 23 to form a complete understanding of the structure of the invention. The view provided by this figure shows, in addition to features described above with respect to FIG. 21 , a cross-sectional view of the blood inlet 358 supported by the housing top 356 and the rake elements 440 mounted on the rake hub 402 .
FIG. 23 is a fragmentary cross-sectional view of the separator-concentrator shown in FIG. 22 . A top plate 442 is secured to the top of the outer wall 412 to confine the blood to the separator during the centrifugal separation. The top plate 442 supports a blood distribution tube 444 that is positioned below and in alignment with the blood inlet port 358 at the first stage when blood is introduced into the separator.
The annular blood overflow chamber 426 has a top plate 446 with a blood flow inlet opening 448 adjacent the top plate 442 and a second vent opening 450 that is radially inward from the blood inlet opening. This allows overflowing blood to enter the chamber during the centrifugal separation phase through the first inlet opening 448 and allows escape of air displaced by the blood through the second vent opening 450 .
The tapered outer wall 418 of the blood reservoir has a tip edge 449 .
A PRP flow passageway 451 leads from the outer separation chamber 453 to the concentrator basket 429 .
The rakes 440 have a terminal tip edge 452 that are positioned adjacent the inner surfaces 454 of the upright screen supports 434 so they closely sweep the surfaces 454 during their rotation. The upright screen supports 434 have a thickness and openings 456 into which gel beads collect during the fast centrifuge phase, placing them beyond the tip edge of the rakes.
The screen 430 has a mesh size that is sufficiently small to prevent escape of the gel beads from the chamber concentration chamber during the final centrifugal separation of the PRP concentrate from the gel beads.
FIGS. 24-27 illustrate the device of FIGS. 19-23 during the phases of the blood separation and concentration. FIG. 24 is a cross-sectional drawing of the device of FIGS. 19-23 after blood has been added, FIG. 25 is a cross-sectional drawing of the device during the centrifugal separation stage producing PRP, FIG. 26 is a cross-sectional drawing of the device during the slow rotation concentration stage, and FIG. 27 is a cross-sectional drawing of the device of during the centrifugal PRP concentrate separation stage.
The blood separation and concentration with the device of this invention proceeds as follows:
Referring to FIG. 24 , a quantity of blood 458 that approximates the volume that can be concentrated (dewatered) by the gel beads is introduced into the blood reservoir 416 through the inlet opening 442 and distribution tube 444 . The blood 458 can be introduced through the needle of the original sample syringe or another device. The blood is shown after is has settled in the bottom of the blood reservoir 416 .
In FIG. 25 , the motor 384 is energized to rotate the separator and concentrator assembly 378 at a fast spin rate that effects centrifugal separation of the more dense erythrocytes in the blood from the PRP. The central tube 360 and attached rake 440 remain stationary during this rapid rotation, and the gel beads 460 are spun by the rotary components and held by the centrifugal force against the screen 430 , beyond the reach of the tips 452 of the stationary rake tips 440 . The centrifugal force causes the blood 458 to flow up the tapered inside wall 418 of the blood reservoir 416 and over the tip edge 449 , to collect against the depth filter 424 as shown in FIG. 25 . The separation is achieved as a function of cell density, sending the most dense erythrocytes outward and through the passageways of the depth filter 424 . The platelets remain in the PRP layer 462 that forms against the depth filter 424 .
After separation of the cells is complete, the rotation of the separator and concentrator assembly 378 is slowed. PRP flow passageways 451 lead from the outer separator chamber 453 to the concentrator basket 429 . The PRP 462 flows from the pores and surface of the depth filter 424 downward through the PRP flow passageway 451 into the concentrating basket 429 . Erythrocytes remain trapped in the pores and passageways of the depth filter 424 so that the PRP 463 reaching the basket 429 is substantially free of erythrocytes.
As shown in FIG. 26 , the PRP 463 flows into contact with the desiccated gel beads 460 that have collected on the base 432 of the concentrating basket 429 . As the beads absorb water from the PRP, they swell, and the PRP immediately adjacent the bead surface thickens and becomes tacky. The continuing slow movement of the concentration basket 429 past the stationary rake 440 and the vertical supports 434 stirs the beads 460 , reducing gel polarization on the bead surface, and breaking up the bead clumps. This slow stirring movement of the rotary components is continued until the water removal stage is completed.
The motor speed is then increased to a fast spin mode, and the centrifugal force moves the gel beads 460 to the surface of the screen 430 . The centrifugal force generated by the spin caused the PRP concentrate 464 to flow away from the surfaces of the beads and through the screen 430 to collect the PRP concentrate in the PRP reservoir as shown in FIG. 27 . The PRP concentrate is removed with a syringe through tube 398 and PRP outlet port 360 .
FIG. 28 is a cross-sectional view of a portable embodiment of this invention. This embodiment includes a blood separation and concentration system in the upper housing 354 that is identical to the blood separation and concentration system described with respect to FIGS. 19-23 . Because these components are identical and to avoid unnecessary redundancy, no separate description of the identical components is provided herein, the description of these elements with respect to FIGS. 19-27 being incorporated by reference. For details about the blood separation and concentration systems, see the description of the components provided hereinabove with respect to FIGS. 19-23 .
The system shown in FIGS. 19-23 comprises a disposable blood separation and concentration unit and a permanent motor control unit. This assembly is optimum of use in a laboratory or surgical setting found in a hospital or medical clinic.
For applications where a permanent motor and control system powered from conventional power sources is not practical, a portable fully integrated embodiment of this invention is provided. The major difference between the embodiment shown in FIG. 24 is the integration of the motor, power supply and control system in a unitary system with the blood separation and concentration system. The lower casing or housing 470 encloses the motor 472 , power supply 474 and control system 476 . The motor 472 is secured to a motor support plate 478 mounted on the motor support suspension 480 . The motor support suspension 480 is secured the lower surface 482 of the base 484 in a position to maintain axial alignment of the motor with the axis of the rotary elements of the separator and concentrator unit. The motor drive shaft is secured to the separator and concentrator assembly by a coupling 485 . The motor 472 is connected to the battery power supply 474 and control system 476 with conventional electrical circuitry (not shown). The battery power supply is electrically connected to the control system 476 with conventional electrical connections 486 . A conventional removable plate 487 can be removably secured to the lower portion of the lower housing 489 in a position that permits insertion of the power supply battery 474 when it is removed. This allows insertion of an active battery immediately before deployment or use of the system.
The control system 476 is a conventional motor controller and timer that establishes and controls the motor speeds during the rapid rotation centrifugation phases of the blood separation and during the concentration stages, and during the slow rotation concentration stage. These stages are the same as are described hereinabove with respect to FIGS. 24-27 .
The weight and size of the separator and concentrator elements are selected to conserve energy and to be fully operational with a standard 9 volt battery. This enables the device to be a completely portable system that does not require external power. It is thus suitable for use in mobile field units and field hospitals where self-powered, fully portable units are needed.
The operation of the embodiment shown in FIG. 28 is the same as is described above with respect to FIGS. 24-27 .
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The PRP separator-concentrator of this invention is suitable for office use or emergency use for trauma victims. The PRP separator comprises a motorized centrifugal separation assembly, and a concentrator assembly. The centrifugal separator assembly comprises a centrifugal drum separator that includes an erythrocyte capture module and a motor having a drive axis connected to the centrifugal drum separator. The concentrator assembly comprises a water-removal module for preparing PRP concentrate. The centrifugal drum separator has an erythrocyte trap. The water removal module can be a syringe device with water absorbing beads or it can be a pump-hollow fiber cartridge assembly. The hollow fibers are membranes with pores that allow the flow of water through the fiber membrane while excluding flow of clotting factors useful for sealing and adhering tissue and growth factors helpful for healing while avoiding activation of platelets and disruption of any trace erythrocytes present in the PRP.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates in general to a device for locking together inner and outer members of an oil or gas well, and particularly to a locking device for locking a drilling wear bushing within a casing hanger.
2. Description of the Prior Art
There are instances in which an inner tubular member must be releasably locked into an outer tubular member within a well. For example, in a subsea well of the type concerned herein, a subsea wellhead housing will be located on the sea floor. A casing hanger will land in the subsea housing. The casing hanger locates at the top of a string of casing that extends into the well. An annular seal will seal between the casing hanger and the wellhead housing.
If the well is to be drilled deeper, the drilling rig at the surface of the water will run drill pipe down through the casing hanger and through the casing for drilling. It is important to avoid damaging the bore of the casing hanger, because eventually, a tubing hanger may land within the casing hanger for supporting production tubing. The operator will lower a wear bushing into the bore of the casing hanger to prevent damage to the casing hanger from the rotating drill pipe.
The wear bushing needs to be retained in the bore of the casing hanger. Without some type of retention mechanism, the wear bushing might be dislodged by circulation of heavy solids or by tripping of the drill pipe through the wellhead during normal drilling operations.
There are various mechanisms for retaining wear bushings, including shear pins, lock rings, or J pins made of steel or other metallic alloys. While workable, users have experienced failure in activating or releasing these devices. It is difficult to recover the wear bushing if the locking mechanism fails to release.
Elastomeric O-rings have been used in standard and shallow cut dove tail grooves on wear bushings to prevent the buildup of fine particles between the wear bushing outer diameter and the casing hanger inner diameter. In some cases, the O-ring will expand into a groove in the wellhead housing so as to resist premature unseating of the wear bushing. The amount of retention in these cases, however, is not sufficient to serve as the primary retention means for retaining the wear bushing with the casing hanger.
SUMMUARY OF THE INVENTION
In this invention, a retaining groove will be formed on one of the inner or outer members, and a reaction groove will be located on the other. These grooves will be positioned so that they will align with each other when the inner member or wear bushing, fully inserts within the outer member or casing hanger. The retaining groove has a deeper portion which joins a shallow portion and which is bounded by a shearing shoulder or side wall. The reaction groove also has a side wall which opposes the shearing side wall of the retaining groove when the inner and outer members are fully inserted together.
A solid elastomeric ring will be carried within the retaining groove. The ring locates in the deeper portion when the inner and outer members are being pushed together. It will protrude into the reaction groove when the inner member fully inserts into the outer member. Picking up on the inner member then causes the shallower portion of the retaining groove to slide upward relative to the ring until the ring locates in the shallower portion. The ring will then be contacted by the opposed shearing side walls. This retains the inner member within the outer member.
The protrusion of the ring from the shallower portion into the reaction groove is sufficient to prevent the inner and outer members from being pulled apart unless sufficient pulling force is applied to cause the ring to shear. Once sheared, a catcher groove located below the retaining groove will catch the portion sheared from the ring. Preferably, the elastomeric ring has a flat side which contacts the retaining groove. This flat side prevents the ring from rolling as the shallower portion slides upward relative to the ring.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is quarter sectional view of a casing hanger, wear bushing, and wellhead housing, showing a lockdown device constructed in accordance with this invention.
FIG. 2 is an enlarged sectional view of a portion of the lockdown device of FIG. 1, and showing the wear bushing in the process of being inserted into the casing hanger.
FIG. 3 is a cross sectional view of the lockdown device of FIG. 1, showing the wear bushing fully inserted into the bore of the casing hanger.
FIG. 4 is an enlarged view of a portion of the lockdown device of FIG. 1, showing the wear bushing being pulled upward relative to the casing hanger.
FIG. 5 is an enlarged cross sectional view of the lockdown device of FIG. 1, showing the wear bushing being pulled from the casing hanger, with the elastomeric ring sheared into two portions.
FIG. 6 is a cross sectional view of an alternate embodiment of the elastomeric ring used with the lockdown device of FIG. 1.
DESCRIPTION OF THE INVENTION
Referring to FIG. 1, wellhead housing 11 is a large tubular member located on the floor of the sea. Wellhead housing 11 has an axial bore 13. A casing hanger 15 lands within the bore 13. Casing hanger 15 will be secured to the upper end of a string of casing (not shown) which extends into the well to a selected depth. Casing hanger 15 has an axial bore 17. An annular seal assembly 19 seals between the casing hanger 15 and the wellhead housing 11.
In the embodiment shown, the operator will drill the well to a greater depth than the depth of the casing to which the casing hanger 15 is secured. Drill pipe will be lowered from a drilling rig (not shown) at the surface, through the casing hanger 15 and into the well for the additional drilling.
To prevent damage to the bore 17, the operator will install a wear bushing 21 in the bore 17. Wear bushing 21 is a tubular metal member with a lower portion which fits securely within the bore 17. An upper portion extends upward a short distance. A shoulder 23 divides the upper and lower portions. Shoulder 23 will land on the rim of the casing hanger 15 when the wear bushing 21 fully lands within the casing hanger 15. Seals 25 and 26 seal the lower portion of the wear bushing 21 to the bore 17.
Conventional means exist for preventing the wear bushing 21 from rotating relative to the casing hanger 15. In the embodiment shown, this includes a longitudinally extending pin 27 which engages a slot 28 located in the upper end of the seal assembly 19. A spring 29 urges the pin 27 downward. A radially extending pin 31 engages a slot 32 in the pin 27 to retain the pin 27.
The lockdown means for locking the wear bushing 21 to the casing hanger 15 includes a retaining groove 33. Retaining groove 33 is formed on the exterior of the lower portion of the wear bushing 21. Groove 33 is circumferential, extending continuously around the wear bushing 21. Groove 33 has a deeper portion 33a which leads to a shallower portion 33b directly below. The deeper portion 33a is arcuate in cross-section. The shallower portion 33b is cylindrical and substantially straight in cross-section The deeper portion 33a slopes gradually through a tapered, conical section to the shallower portion 33b.
The axial length of the deeper portion 33a is about the same as the axial length of the shallower portion 33b. The inner diameter of the deeper portion 33a is less than the inner diameter of the shallower portion 33b. In the embodiment shown, the depth of the shallower portion 33b is approximately 57 percent of the depth of the deeper portion 33a. The depth is measured by measuring the radial distance from the exterior of the lower portion of wear bushing 21 to the inner diameters of the portions 33a, 33b.
The deeper portion 33a leads smoothly into an insertion side wall 35 on its upper end. The insertion side wall 35 has a portion that is perpendicular to the longitudinal axis of the wear bushing 21 and faces downward. The shallower portion 33b leads on its lower end smoothly into a shearing side wall or shoulder 37. The shearing side wall 37 is curved, but faces generally upward and outward. The shearing side wall 37, including the transition portion from the shallower portion 33b, is about one-fourth of the radius of a circle.
The retaining groove 33 is positioned so as to locate directly across from a reaction groove 39 when the wear bushing 21 locates fully within the casing hanger 15. The reaction groove 39 in the embodiment shown is a conventional groove that has been present on prior art casing hangers 15 for other purposes, such as serving as means for connecting a running tool (not shown) for running the casing hanger 15 and seal assembly 19. The reaction groove 39 will still be used for the other purposes, but in this invention, has an additional function The reaction groove 39 in the embodiment shown thus has a conventional profile.
The reaction groove 39 will have a downward facing shoulder or side wall 41, which may be called a shearing side wall for the purposes of this invention. The shearing side wall 41 is a straight conical side wall, that faces downward and inward at about a 65 degree angle relative to the longitudinal axis of the casing hanger 15. The remaining portion of the reaction groove 39 is also conical, tapering downward about a ten degree angle relative to the longitudinal axis of the casing hanger 15. In the embodiment shown, the maximum depth of the reaction groove 39, which is at the intersection of the shearing side wall 41 with the remaining portions of groove 39, is about the same as the depth of the retaining groove shallower portion 33b. A bevel 43 will be located on the bore 17 of the casing hanger 15 at the rim of the casing hanger 15.
An elastomeric ring 45 locates in the retaining groove 33. Ring 45 is preferably of a buna N material, having a hardness of 85-95 durometer. Ring 45 is solid and continuous, not split at any point. In the embodiment of FIGS. 1-5, ring 45 has the shape of an O-ring, except for a flat 47 formed on its inner diameter. This gives ring 45 the general shape of a "D". The flat 47 is in a longitudinal plane and offset from the center line 55 of the cross-sectional diameter of ring 45. Flat 47 will be positioned so that it will contact the shallower portion 33b when the wear bushing 21 is pulled upward from the casing hanger 15.
In the embodiment of FIG. 6, ring 45' is the same, except the intersection of the flat 47' with the cylindrical exterior of ring 45' is not a radius, as in the embodiment of FIGS. 1-6. Rather, the surface joining the flat 47' is perpendicular to the flat 47" and tangent to the cylindrical portion of the ring 45'. This gives the ring 45' more of a true "D" shape. In the embodiment of FIG. 6, the axial extent of the flat 47 is about the same as the axial extent of the ring 45 from its lowermost point to its uppermost point. In both embodiments, the radial distance from flat 47' to the outer diameter of ring 45' is about 83 percent of what the cross-sectional diameter of the ring 45' would be if the flat 47' did not exist.
Referring to FIGS. 1 and 6, a catcher groove 49 locates below the retaining groove 33. Catcher groove 49 will be spaced axially downward a selected distance below the shearing side wall 37. Catcher groove 49 has a lower side wall 51 that is perpendicular to the axis of the wear bushing 21. The catcher groove 49 has an upper side wall 53 that is conical and faces downward and outward. Catcher groove 49 serves to catch a portion of the ring 49 that is sheared, as illustrated in FIG. 6.
The cross-sectional diameter of the elastomeric ring 45 is the same as the diameter of the radius forming the retaining groove deeper portion 33a. The depth of the retaining groove deeper portion 33a is selected so that ring 45 will deform without any damage as the wear bushing 21 enters the casing hanger 15. Less than one half of the ring 45 will protrude outward from the retaining groove deeper portion 33a. Preferably, only about 24 percent of the ring 45 protrudes from the groove deeper portion 33a.
When the ring 45 is in the shallower portion 33b, approximately 44 percent of the ring 45 will protrude. These percentages are determined by dividing the radial distance from the outer diameter of the ring 45 to the exterior of the wear bushing 21 by the radial dimension of the ring 45 from flat 47 to the outer diameter of ring 45. The midpoint 55 will be recessed within the groove deeper portion 33a when the ring 45 is in the deeper portion 33a, as shown in FIG. 2. When in the shallower portion 33a, the midpoint 55 will also be recessed within the shallower portion 33a, but to a lesser extent.
In operation, the operator will lower the wear bushing 21 on a conventional running tool (not shown). Initially, the ring 45 will be located in the deeper portion 33a of the retaining groove 33, as shown in FIG. 2. The lower portion of the wear bushing 21 will stab into the bore 17 of the casing hanger 15. The elastomeric ring 45 will contact the bevel 43.
The insertion side wall 35 will force the ring 45 to deform as the wear bushing 21 moves downward into the casing hanger bore 17. Arrow 54 in FIG. 2 illustrates this downward movement. When the wear bushing 21 reaches its fully inserted position, illustrated in FIG. 3, the ring 45 will return back to its original configuration, with a portion protruding into the reaction groove 39. At this point, the ring 45 will not be touching any of the surfaces of the reaction groove 39. The ring 45 will still be located in the deeper portion 33a. The seal 25 will be sealing against the bore 17. The seal 26 will be in sealing contact with the bevel 43.
The operator will then pick up on the string to determine whether or not the wear bushing 21 has properly locked to the casing hanger 15. Arrow 56 in FIG. 4 illustrates this upward movement When this occurs, the wear bushing 21 will move upward a short distance relative to the casing hanger 15. The shallower portion 33b will move upward relative to the ring 45, but the ring 45 will be retained against movement by the shearing side wall 41 of the reaction groove 39. The shallower portion 33b will slide along the flat 47. The flat 47 will prevent the ring 45 from rolling during this upward movement.
When the shearing side wall 37 contacts the ring 45, the ring 45 will be pressed between the shearing side walls 37 and 41, as shown in FIG. 4. The operator will detect the increase in force as he pulls upward, and will thus determine that the wear bushing 21 is properly locked in place. He then can release the running tool and retrieve it to the surface. The operator will then lower a drill bit through the wear bushing 21 to begin drilling
After drilling has been completed, to retrieve the wear bushing 21, the operator again lowers the running tool into engagement with the wear bushing 21. The operator picks up the drill string and applies upward force. Once a sufficient upward force has been applied, the ring 45 will shear along the shear line 57, as shown in FIG. 5. This releases the wear bushing 21 from the casing hanger 15. The operator can then begin pulling the wear bushing 21 back to the surface.
A portion of the ring 45 will remain in the retaining groove 33. The other portion of the ring 45 will be trapped by the catcher groove 49 after the wear bushing 21 moves up a short distance. The other portion of the ring 45 will remain in the catcher groove 49 and be brought to the surface along with the wear bushing 21.
The force required to insert the wear bushing 21 into the casing hanger 15 is much less than the force required to retrieve it This difference in force results because when inserting, the ring 45 locates in the deeper portion 33a of retaining groove 33, and when pulling, the ring 45 locates in the shallower portion 33b. Tests have shown that for one embodiment, the insertion force is less than 8,000 pounds. The pull out force is 50,000 pounds or greater.
The invention has significant advantages. The lockdown device effectively retains the wear bushing with the casing hanger. It is not as subject to failure as prior art mechanical locking devices. A much lighter push in force is required than a pull out force. The lockdown device can be used for applications other than a wear bushing within a casing hanger.
While the invention has been shown in only one of its forms, it should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the invention.
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A device for retaining tubular inner and outer members together in a well allows the members to be pulled apart with a sufficient shear out force. The members have mating retaining and reaction groooves. The retaining groove has a deeper portion joining a shallower portion which is bounded by a shearing side wall. The reaction groove has a shearing side wall which opposes the shearing side wall of the retaining groove when the inner and outer members are fully inserted together. A solid elastomeric ring is carried within the retaining groove. The ring locates in the deeper portion when the inner and outer members are being pushed together. When a pulling apart force is applied, the shallower portion slides relative to the ring until the ring locates in the shallower portion and is contacted by the opposed shearing side walls. The protrusion of the ring from the shallower portion into the reaction groove is sufficient to prevent the inner and outer members from being pulled apart from each other unless sufficient pulling force is applied to cause the ring to shear.
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This application claims the priority of Provisional No. 60/120,393, filed on Feb. 17, 1999.
FIELD OF THE INVENTION
This invention concerns a process for the addition of volatile materials, such as catalysts or treatment agents, to prepolymers prior to or during solid state polymerization processes and the subsequent solid state polymerization process. Optionally, the volatile materials, having completed their function, may be removed from the polymer during or after the solid state polymerization process.
TECHNICAL BACKGROUND
Various publications describe the uses of and methods of using catalysts or other additives during a solid state polymerization process of condensation polymers.
In these polymerization processes, it has been customary to introduce the catalyst species into the melt phase of the polymerization process followed by solidification and, optionally, crystallization. Thus, when said catalyst treated polymer is subjected to solid state polymerization, the catalyst is available to exert its catalytic action. Catalyst remains in the finished, solid state polymerized product and all end use polymer products contain measurable quantities of the catalytic species. In any subsequent use, where the catalyst-containing polymer is exposed to heat, a molecular weight increasing condensation reaction may start to occur because the catalyst is still present.
The present invention adds the catalyst or other treatment agent as a gas or dissolved in a liquid, which improves the contact of the polymer, typically in the form of a particle or a pastille, with the catalyst or treatment material and, if the agent is sufficiently volatile, also facilitates removal of the agent from the system. The agent is then removed easily from the system after contact with the polymer by the inert gas sweep employed in solid state polymerization processes and the resulting polymerization product is substantially free of catalyst or treatment agent.
SUMMARY OF THE INVENTION
This invention provides a process for the addition of volatile treatment agents to a solid state polymerization in a condensation polymerization process comprising:
a) establishing a recirculating gas flow over polymer particles undergoing solid state polymerization;
b) introducing a volatile treatment agent into said recirculating gas flow; and
c) contacting said polymer particles with said volatile treatment agent under solid phase polymerization conditions.
This invention further provides a process for the addition of volatile treatment agents to a solid state polymerization in a condensation polymerization process comprising:
a) contacting polymer particles with a solution of a volatile treatment agent in a suitable solvent;
b) removing said solvent to yield polymer particles coated with or containing said treatment agent;
c) subjecting said polymer particles to solid state polymerization in the presence of a gas flow.
This invention may be used with additive materials such as catalysts, treatment agents, catalyst deactivators, nucleating agents, antioxidants, ultraviolet stabilizing agents, plasticizers, thermal stabilizers, comonomers, tinting agents and barrier property enhancers. In some of these embodiments it is desirable to remove the additive material after contact with the polymer, although in some embodiments herein the additive is incorporated into the polymer as part of the final product.
DETAILED DESCRIPTION OF THE INVENTION
The process of the present invention applies to the polymerization of polymers where the polymerization process is subject to catalysis or other treatment. Suitable polymer types include polyesters, polyamides and polycarbonates, including homopolymers and copolymers of these various polymer types. The polymer to which the process of the present invention is applied typically has a degree of polymerization in the range of from 5 to 25.
In working with these polymers it has been customary to introduce the catalyst species into the melt phase of the polymerization process followed by solidification and crystallization.
According to the practice of the present invention, a catalyst or treatment material effective in solid state polymerization is introduced into the solid state polymerization stage via a gas stream that is introduced to, and vented from, the solid state polymerizer. It is also within the scope of the present invention to introduce the catalyst or treatment agent via a gas stream introduced to a preheater or conditioner vessel upstream of the solid phase polymerizer.
The catalyst or treatment material must be sufficiently volatile, i.e., it has a high enough vapor pressure, to be introduced via the gas stream, and, optionally, to also be removed via the gas stream. Thus, if desirable, by stopping the vapor borne supply of catalyst or treatment material, but continuing the vapor sweep through the solid state polymerization vessel, the amount of catalyst remaining in the subject polymer may be substantially reduced. This offers potential utility both in polymer purity and stability. In certain condensation polymers known in the art, residual catalyst lends itself to polymer instability, especially during the course of post-polymerization treatment steps or uses that involve exposure to elevated temperatures.
Alternatively, the additive may be introduced by use of a solution of the additive in a suitable solvent, followed by removal of said solvent. In this embodiment, polymer particles are contacted with the treatment agent, then after solvent removal, the coated polymer particles are subjected to solid state polymerization in the presence of a vapor sweep. If the agent is sufficiently volatile, and the solid state polymerization is sufficiently lengthy, the additive may be completely removed by the vapor sweep leading to the same potential advantages as described above for vapor state addition of volatile agents.
As mentioned above additives such as catalysts, treatment agents, catalyst deactivators, nucleating agents, antioxidants, ultraviolet stabilizing agents, plasticizers, thermal stabilizers, co-monomers, tinting agents and barrier property enhancers may be contacted with the polymer in the solid state polymerizer. Examples of catalyst additives useful herein include the following: benzene-sulfonic acid, methanesulfonic acid triflic acid (trifluoromethanesulfonic acid), toluene sulfonic acids, especially p-toluene sulfonic acid, other volatile Bronsted and Lewis acids, tetra isopropoxy titanate and tri butoxy antimonate. Volatile Bronsted acids are preferred. It is to be noted that Bronsted acids are generally not useful in conventional solid state polymerization processes of polyesters due to excessive dialkylene glycol formation.
Certain grades of polyester, such as for the bottle resin market, are typically polymerized to high molecular weight in the melt phase, i.e., to ˜0.65 IV, and then subjected to post-polymerization solid phasing to raise the molecular weight even further to levels needed for bottle resins or for industrial fibers. Example 4 shows that the process of the present invention can be used to increase rates of this post polymerization solid phasing.
Viscosities reported below were obtained with a Viscotek Forced Flow Viscometer. Polyesters were dissolved in trifluoroacetic acid/methylene chloride. The viscosity data reported have been correlated to the intrinsic viscosity in 60/40 wt % phenol/tetrachloroethane following ASTM D4603-96.
EXAMPLES
Example 1
Catalyst-free polyethylene terephthalate pastilles having a degree of polymerization of about 20 were dried for 16 hours in a vacuum oven at 110° C. In a nitrogen-flushed drybox, 75 gram quantities of these pastilles were added to 160 mL of 0.3 molar solutions of various catalysts according to the table below. The mixture was refluxed for 60 minutes, distilling off 11 to 32 mL of solvent. The pastilles were then separated from the solution and washed with pentane and dried at reduced pressure for 16 hours.
Catalyst Solutions
ID
Composition
A
Ti(O-i-Pr) 4 in heptane
B
C 6 H 5 SO 3 H in methylene chloride
C
Sb(OC 4 H 9 ) 3 in heptane
D
Pure Heptane, with no catalyst (control)
The pastilles were then solid-phase polymerized at 240° C. using a nitrogen purge for 24 hours. The IV results are summarized in the table below.
Time
Ti(O-i-Pr) 4
C 6 H 5 SO 3 H
Sb(OC 4 H 9 ) 3
Control
t 0 (before SSP)
0.162
0.159
0.166
0.165
5 minute
0.176
—
—
—
1 hour
—
0.263
0.181
—
2 hours
0.285
0.511
0.313
—
4 hours
—
—
—
0.171
6 hours
0.419
—
—
—
24 hours
0.625
0.988
0.457
0.215
These results show that the C 6 H 5 SO 3 H catalyst is the most active catalyst in this series under these conditions.
The pastilles treated with the C 6 H 5 SO 3 H catalyst analyzed for 1068 ppm S before solid phase polymerization and 145 ppm S after solid phase polymerization. A sample of these pastilles after solid phase polymerization was subjected to a vacuum oven at 110° C. for 16 hours which further reduced their sulfur content to 15 ppm S. A sample of these pastilles after solid phase polymerization was melted under vacuum for 60 minutes, which reduced their sulfur content to 130 ppm S. These results show that the absorption of the benzene sulfonic acid catalyst is reversible.
The pastilles treated with the C 6 H 5 SO 3 H catalyst analyzed for 1.1 weight % diethylene glycol before solid phase polymerization and 1.9 weight % diethylene glycol after solid phase polymerization. This data shows that the diethylene glycol remains within acceptable limits using this catalyst under these conditions.
Example 2
The polyethylene terephthalate oligomer used in this experiment contained 275 ppm Sb catalyst, had 2 mole % isophthalic acid comonomer, and possessed a degree of polymerization of 20. The pastilles weighed 16 mg/particle on average. The end group composition was 225 meq/kg of carboxyl groups with essentially all of the remainder being hydroxyl groups. Fifteen grams of this oligomer was solid-phase polymerized using dry nitrogen at 230° C. which had been passed over 3 grams of benzene sulfonic acid. The catalyst is added via the gas phase in this experiment. The total polymerization time was 24 hours. This sample is designated A in the table below. In a separate experiment, fifteen grams of this oligomer was exposed to a solution of 5 grams of benzene sulfonic acid in 100 mL of methylene chloride for 30 seconds. The pastilles were dried and solid phase polymerized as above. This sample is designated B in the table below. A third sample of these oligomer pastilles was solid phase polymerized as in the above procedure with no additional catalyst, as a control. This sample is designated C in the table below. The table shows the intrinsic viscosity as a function of time.
SAMPLE:
Time (hours)
A
B
C
0
0.209
0.209
0.209
1
0.334
0.329
0.249
6
0.497
0.432
0.271
24
0.639
0.616
0.408
These results show that the gas phase catalyst addition provided the highest rate of polymerization in this series. The end group analysis after 24 hours of solid phasing of sample A, the one using the gas phase catalyst, shows 6 meq/kg of hydroxy end groups and 99 meq/kg of carboxyl end groups. This end group analysis shows that the hydroxy end groups are essentially depleted, limiting further molecular weight enhancement.
Example 3
The polyethylene terephthalate oligomer used in this experiment contained 275 ppm Sb catalyst, had 2 mole % isophthalic acid comonomer, and possessed a degree of polymerization of 20. The pastilles weighed 16 mg/particle on average. The end group composition was 225 meq/kg of carboxyl groups with essentially all of the remainder being hydroxyl groups. Fifteen grams of this oligomer was solid-phase polymerized using dry nitrogen at 230° C. which had been passed over 3 grams of benzene sulfonic acid. The catalyst is added in the gas phase in this experiment. The total polymerization time was 24 hours. This sample is designated A in the table below. In a separate experiment, fifteen grams of this oligomer was solid-phase polymerized using dry nitrogen at 230° C. which had been passed over 1.0 grams of benzene sulfonic acid, again adding catalyst in the gas phase as part of the nitrogen stream. This sample is designated as sample B in the table below. The table shows the intrinsic viscosity versus time.
SAMPLE
A
B
time
0.209
0.209
start
1 hour
0.282
0.366
6 hours
0.471
0.549
24 hours
0.741
0.727
This data shows that the smaller catalyst charge is sufficient to provide significant catalytic effects and that the effect of catalyst is very large in the first 6 hours of polymerization under these conditions with this catalyst.
Example 4
This example demonstrates the addition of catalyst after melt phase polymerization as a means of enhancing the rate of subsequent solid phase polymerization.
Crystar® Merge 3934 polyethylene terephthalate is a typical commercial grade high molecular weight polyester prepared in a melt process using antimony trioxide as catalyst. It is obtainable from E. I. du Pont de Nemours and Company, Wilmington, Del. In this experiment the polymer used was in the form of pellets that had been first crystallized by heating to 160° C. for 5 hours. Fifteen gram aliquots of these pellets were soaked for 3 minutes in a solution consisting of 5.0 g of benzene sulfonic acid in 100 mL of methylene chloride. The catalyst solution was drained off of the pellets and then the pellets were dried under vacuum. The catalyst coated pellets were solid state polymerized using a dry nitrogen stream. The inherent viscosity results are tabulated below. These data show that treatment of the pellets of melt phase polymerized polyester with catalyst in this way enhances the rate of solid state polymerization.
Inherent Viscosity
Sample
Temperature
0 hrs
1 hr
6 hrs
24 hrs
no added catalyst
230° C.
0.73
0.770
0.871
1.025
no added catalyst
240° C.
0.73
0.758
0.892
1.039
Benzene sulfonic
230° C.
0.73
0.724
0.852
1.100
acid catalyst
Benzene sulfonic
240° C.
0.73
0.778
0.889
1.174
acid catalyst
Example 5
The procedure of Example 2 was repeated except with a pre-polymer low in acid end groups and rich in ethylene glycol end groups. This oligomer had an initial acid end group concentration of 77 meq/kg and an initial ethylene glycol end group concentration of 552 meq/kg. In contrast, the control had an acid end group concentration of 225 meq/kg, with the remaining end groups being ethylene glycol end groups. The inherent viscosity as a function of time in solid stating is tabulated below. These data show that solid-phase polymerization is faster at these lower ethylene glycol end group concentrations.
Time(hrs)
Temp.(° C.)
IV(Low Carboxyls)
IV(High Carboxyls)
0.0
240
0.26
0.25
1.0
240
0.52
0.35
6.0
240
0.67
0.49
24.0
240
0.92
0.64
0.0
230
0.26
0.25
1.0
230
0.42
0.31
6.0
230
0.63
0.45
24.0
230
0.81
0.61
0.0
220
0.26
0.25
1.0
220
0.43
0.31
6.0
220
0.56
0.40
24.0
220
0.70
0.52
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This invention concerns a process for the addition of volatile materials to prepolymers prior to or during solid state polymerization processes and the subsequent conducting of said solid state polymerization process.
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CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation in part of application Ser. No. 10/313,198, filed on Dec. 6, 2002 which is a continuation-in-part of application Ser. No. 10/295,390, filed on Nov. 15, 2002 which is related to and claims the priority of provisional application Ser. No. 60/340,062, filed Dec. 8, 2001, provisional application Ser. No. 60/365,918, filed Mar. 20, 2002, and provisional application Ser. No. 60/369,988, filed Apr. 4, 2002. The entire contents of these applications are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The invention is in the field of cardiac health, more specifically in the field of minimally invasive methods for cardiac ablation.
[0003] Heart muscle contractions are controlled by electricity flowing throughout the heart. Normally, this electrical flow is in a regular, measured pattern. Sometimes, however, the electrical flow gets blocked or travels the same pathways repeatedly, creating something of a “short circuit” that disturbs normal heart rhythms. Medicine often helps this condition. In some cases, however, the most effective treatment is to physically destroy the tissue where the short circuit occurs. The procedure to destroy this tissue is called cardiac ablation.
[0004] Ablation can be conducted using different types of energy sources such as radiofrequency (RF), microwave, laser, ultrasound, radiation using a beta source, and cryothermy (cold temperatures). The energy is delivered via an instrument, such as a catheter, which is inserted into the body and the tip of which is placed at the site to be ablated. The instrument may have a shaped tip to cover a greater surface area. Inflatable balloons to deliver the energy have also been developed, which also allow for ablation of a greater surface area.
[0005] Cardiac ablation can be performed inside the heart (endocardial) or on the outside of the heart (epicardial). The location of the ablation performed depends upon the type of arrhythmia and the presence of other heart disease.
[0006] Epicardial ablation is often performed using traditional “open” surgery, where the patient's chest is opened up to allow access to the heart. Epicardial ablation is thus easy in one respect—the site to be treated can be relatively easily accessed. Endocardial ablation on the other hand has the additional complication of requiring access to the interior of the heart. Endocardial ablation is also commonly performed using traditional open surgery but endocardial ablation is also conducted using percutaneous access. During this procedure a catheter is inserted at the femoral or carotid artery and threaded into a specific area of the heart. Travel of the catheter is monitored using a fluoroscope. This procedure is often called percutaneous cardiac ablation.
[0007] Ablation is used in all areas of the heart. Most often, cardiac ablation is used to treat rapid heartbeats that begin in the upper chambers, or atria, of the heart. As a group, these are known as supraventricular tachycardias, or SVTs. Types of SVTs are atrial fibrillation and atrial flutter, AV nodal reentry tachycardia (AVNRT), AV reentrant tachycardia, and atrial tachycardia. Cardiac ablation can also be used to treat accessory pathways tachycardia which is a rapid heart rate due to an extra abnormal pathway or connection between the atria and the ventricles. The impulses travel through the extra pathways as well as through the usual route. This allows the impulses to travel around the heart very quickly, causing the heart to beat unusually fast.
[0008] Less frequently, ablation is used to treat heart rhythm disorders that begin in the heart's lower chambers, known as the ventricles. Ventricular tachycardia (V-tach) is a rapid heart rhythm originating from the ventricles of the heart. The rapid rate prevents the heart from filling adequately with blood; therefore, less blood is able to pump through the body. This can be a serious arrhythmia, especially in people with heart disease.
[0009] In all types of ablation procedures, once the catheter or other device reaches the heart, electrodes at the tip of the catheter gather data and a variety of electrical measurements are made. The data pinpoints the location of the faulty electrical site. Once the damaged site is confirmed, the ablation energy is delivered to destroy a small amount of tissue, hopefully ending the disturbance of electrical flow through the heart and restoring a healthy heart rhythm.
[0010] Percutaneous cardiac ablation has several issues that make it less than desirable. For one thing, the catheters that are used for percutaneous cardiac ablation are limited in size because they must be threaded through the vasculature into the heart. This means that the area of tissue that can be ablated is very small and the tip must be maneuvered around quite a bit if the area to be treated is large. In cases where more than one type of tool is used, each tool must be threaded separately, adding to the length of the process.
[0011] Maneuverability of a catheter which is threaded such a long distance is limited, which means that it is difficult and sometimes impossible to locate the catheter electrode tip exactly where the cardiac tissue needs to be ablated. This adds to the total length of the procedure. It also means that the ablation is sometimes less effective than required. Another issue with percutaneous access can be various vascular complications such as bleeding, dissection, and rupture of a blood vessel. Moreover, some areas of the heart are difficult to access percutaneously.
[0012] Accordingly, to avoid the disadvantages of percutaneous cardiac ablation, the present invention provides a method for endocardial ablation using minimally invasive access to the interior of the heart. The area of the heart that is accessed is the apical area of the heart, which is the rounded inferior extremity of the heart formed by the left and right ventricles. In normal healthy humans it generally lies beneath the fifth left intercostal space from the mid-sternal line.
[0013] Access to the interior of the heart via the apex (trans-apical access) is taught in U.S. Pat. No. 6,978,176 to Lattouf. This patent is primarily directed to mitral valve repair but the method taught therein is also described as being useful for ablation.
[0014] Endocardial ablation using trans-apical delivery is advantageous in that it is not limited by the space that is available within the vasculature. The instruments that are used are shorter than those used for percutaneous access, meaning they can be maneuvered more easily and accurately.
SUMMARY OF THE INVENTION
[0015] The present invention is directed to methods and devices for performing endocardiac ablation. The methods rely upon access to the interior of the heart through the wall of the heart at its apex.
[0016] The procedure generally includes first gaining access to the patient's chest cavity through the chest cavity. The patient's heart wall is pierced to provide a passageway through the heart wall to the left or right ventricle. The passageway is formed through a region of the heart wall at or near the apex of the patient's heart.
[0017] In one embodiment, an instrument port is installed in the ventricular wall passageway. The port is configured to enable passage of instruments for the procedure through the heart wall into the heart chamber while preventing loss of blood through the passageway. An instrument port is not required but is preferred in some respects.
[0018] The ablation catheter or other ablation tool is then passed through the instrument port or passageway and into the area to be treated, such as the left atrium. In one embodiment, an instrument guide is used, to provide a guide for the ablation tool. Once the ablation procedure is completed, the instruments are withdrawn through the instrument port (if one is used) and then the opening in the patient's chest. The instrument port may be left in place or the port may be removed and the passageway sutured or otherwise suitably closed.
[0019] The invention will become more apparent from the following detailed description and accompanying exemplary drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a perspective view of a patient's chest, partially illustrating the location of the patient's heart within the chest cavity, with part of the heart wall removed to expose the left ventricular and atrial chambers and showing the method of the present invention for ablation in the left atrium.
[0021] FIG. 2 is an elevational view of an ablation instrument of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0022] The present method can be used with ablation devices that deliver various types of energy, such as radiofrequency (RF), microwave, laser, ultrasound, radiation using a beta source, and cryothermy (cold temperatures). Some commercially available devices may be suitable for use in the invention. However, devices used for percutaneous ablation are not entirely suitable because they are longer and more flexible than is desirable. Devices used for open heart ablation may not be suitable because they may be larger than is desired for insertion through the chest trocar and the optional heart wall port. However, in general, the various types of ablation instruments that are currently used, and that are anticipated for use, can be modified for use in the invention.
[0023] FIG. 1 demonstrates the method of the invention for ablation in the left atrium. In this embodiment, an instrument port 12 is implanted at the apex 17 of the left ventricle. Instrument guide 14 is inserted through chest trocar 16 , through the instrument port 12 , into the left ventricle 18 , past the mitral valve 20 , and into the left atrium 22 . Ablation catheter 24 is threaded through the instrument guide 14 so that its tip 26 is in the left atrium.
[0024] The chest trocar 12 can be one that is commercially available, such as those available from U.S. Surgical and others. It is placed in a manner known to those skilled in the art, preferably though an intercostal space between two of the patient's ribs.
[0025] To the extent required, the patient's deflated lung is moved out of the way, and then the pericardium on the patient's heart wall is removed to expose a region of the epicardium at the heart apex. The patient's heart wall is pierced at the exposed epicardial location using a piercing element such as a 14 gauge needle. A guide wire is advanced through the inner lumen of the needle into the heart chamber to the area of the heart to be treated, such as the left atrium. The penetrating needle may then be removed leaving the guide wire in place.
[0026] Using a series of dilators placed over the guidewire, a hole is formed large enough for insertion of the instrument port 14 . The port is configured to enable passage of instruments for the procedure through the heart wall into the heart chamber while preventing loss of blood through the passageway and preferably includes a one-way valve.
[0027] The port can be the port disclosed in U.S. Pat. No. 6,978,176 to Lattouf. Other ports that can be used are disclosed in U.S. Publication No. 2006/0074484 to Huber and U.S. Publication No. 2007/0027534 to Bergheim et al. Especially preferred instrument ports are the ones described in U.S. patent application Ser. No. ______ to Lattouf et al., filed on Apr. 6, 2007 as Express mail # EQ230030562US.
[0028] After the instrument port 14 is placed into position, in the left ventricular apex as shown in FIG. 1 , the instrument for performing the ablation procedure (such as ablation catheter 24 ) is passed through the instrument port 14 . As shown in FIG. 1 , the ablation catheter 24 is inserted through the port 12 , into the left ventricle 18 , through the mitral valve 20 , and into the left atrium 22 .
[0029] In one embodiment, an instrument guide is inserted through the instrument port, or through the heart wall if a port is not used, to provide a guide for the ablation tool. The instrument guide is a cylindrical, stiff tube with desirably a steerable tip to steer the ablation tool functional head to the desired location. An especially preferred instrument guide is the one described in U.S. patent application Ser. No. ______ to Lattouf et al., filed on Apr. 6, 2007 as Express mail # EQ230030562US.
[0030] While an instrument port and an instrument guide are used in the preferred embodiment of the method, they are not required. The heart wall can be pierced as described above and the hole enlarged as described above. The ablation tool can simply be inserted through the enlarged hole and the tip moved to the desired location. If a percutaneous ablation catheter is used, the instrument guide is especially helpful to provide support to the catheter.
[0031] Examples of percutaneous access catheters which can be used are the Livewire TC ablation catheters (RF energy) and Epicor cardiac ablation system (high intensity focused ultrasound), both offered by St. Jude Medical, and the Artic Circler circular cryocatheter offered by Cryocath Inc. Many other percutaneous access ablation catheters can also be used.
[0032] In one embodiment, a specially designed ablation tool is used which is stiff enough to be inserted through the heart wall and guided to the desired location. FIG. 2 shows this ablation tool 40 in more detail. The ablation tool 40 has a relatively stiff body portion compared to percutaneous access catheters and is relatively short compared to percutaneous access catheters. Desirably the ablation tool is about 5 to 25 cm in length, more desirably about 8 to 18 cm. The proximal end 42 of the ablation tool will extend out of the patient's body and has a handle 44 attached. The distal end 46 includes functional distal tip 48 and desirably is steerable via the handle. Various methods for steering the distal tip of a catheter are known in the art and can be used for the ablation tool 40 . Various ablation energies are known in the art and can be used in ablation tool 40 . The primary differences between ablation tool 40 and prior art percutaneous ablation catheters are the length and stiffness of the tool 40 . These characteristics enable the ablation tool 40 to be used for transapical ablation. The tool can be used without the need for an instrument port or instrument guide (although these can be used if desired as discussed above).
[0033] The ablation tool body can be made from a stiff material such as PEBAX® or polystyrene. The body portion is desirably stiff enough to be pushable and maneuverable. The outer diameter of the ablation tool is preferably about 2 to 45 French.
[0034] Once the ablation procedure is completed, the instruments for the procedure are withdrawn through the instrument port and then the opening in the patient's chest. The instrument port will close upon instrument removal to eliminate or at least minimize blood leakage through the port. The instrument port may be left in place or the port may be removed and the passageway sutured or otherwise suitably closed.
[0035] Modifications and variations of the present invention will be apparent to those skilled in the art from the forgoing detailed description. All modifications and variations are intended to be encompassed by the following claims. All publications, patents, and patent applications cited herein are hereby incorporated by reference in their entirety.
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Methods and devices for performing endocardiac ablation by accessing the interior of the heart through the wall of the heart at its apex.
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CROSS REFERENCE TO RELATED APPLICATIONS
The present application is related to U.S. patent application Ser. No. 12/983,351 entitled MICROWAVE FILTER which was filed on Jan. 3, 2011, is assigned to the assignee of the present application and is incorporated by reference herein in its entirety. The present application is related to U.S. patent application Ser. No. 12/983,383 entitled METHODS AND APPARATUS FOR RECEIVING RADIO FREQUENCY SIGNALS, now U.S. Pat. No. 8,478,223, which was filed on Jan. 3, 2011, is assigned to the assignee of the present application and is incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
The present invention relates in general to microwave signal processing circuitry and, more particularly, to a microwave filter illustrated in a bandpass filter implemented in microstrip circuitry for which it is initially being used.
Bandpass filters are designed to pass a desired range of frequencies and to reject others above and below the desired range of frequencies. A common characteristic of bandpass filters is that they also pass higher frequencies, usually at the third and higher odd multiples of the desired range of frequencies. When the passage of the higher frequencies is not desirable, additional filtering, such as a low-pass filter or a band-reject filter, is required to suppress the higher frequency responses of the bandpass filter. Such additional filtering requires the use of additional printed circuit board space, and the longer lengths traversed by the radio frequency signal causes additional losses.
SUMMARY OF THE INVENTION
A bandpass filter is tuned and designed to allow a passband, a range of frequencies, to pass with low loss while suppressing frequencies above and below the passed range of frequencies. Circuitry is included into the existing structure of the bandpass filter so that higher frequencies can also be suppressed to thereby reject a band of frequencies at a selected odd multiple of the passed frequency range.
In accordance with the teachings of the present application, a microwave filter comprises a plurality of vertical microstrip elements placed parallel to one another. The plurality of vertical microstrip elements have upper ends that are open circuited and lower ends that are connected to ground potential. At least one horizontal microstrip element connects each of the plurality of vertical microstrip elements to one another, and a spurline is formed in the at least one horizontal microstrip element. In this way, the filter passes a band of frequencies defined by the vertical microstrip elements, connection points of the at least one horizontal microstrip element, the location of a signal input point of the filter and the location of a signal exit point of the filter, and the filter blocks a band of frequencies defined by the spurline formed in the at least one horizontal microstrip.
The plurality of vertical microstrip elements (P) may be greater than two and the at least one horizontal microstrip element then comprises a plurality equal to the plurality of vertical microstrip elements minus one (P−1).
The frequencies of the blocked band of frequencies is substantially equal to an odd multiple of the frequencies of the passed band of frequencies. For example, the frequencies of the blocked band of frequencies may be substantially equal to three times the frequencies of the passed band of frequencies.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
The following detailed description of the preferred embodiments of various embodiments of the present invention can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals, and in which:
FIG. 1 shows a conventional design for a microstrip bandpass filter;
FIG. 2 shows a characteristic frequency response curve of a bandpass filter, such as the bandpass filter of FIG. 1 ;
FIG. 3 shows a conventional design for a notch filter where a spurline is formed in a section of microstrip circuit;
FIG. 4 shows a characteristic frequency response curve of a notch filter such as the notch filter of FIG. 3 wherein odd harmonics of the desired notch frequency are also rejected;
FIG. 5 shows a compact embodiment of a bandpass filter in accordance with the teachings of the present application wherein no third order response is created; and
FIG. 6 shows a frequency response of the passband filter of FIG. 5 wherein the frequency range around 5 GHz is passed while lower and higher frequencies including frequencies in the range of three times the desired frequency range, i.e., around 15 Ghz, are rejected.
DETAILED DESCRIPTION OF THE INVENTION
In the following detailed description of the illustrated embodiments, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration, and not by way of limitation, specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and that changes may be made without departing from the spirit and scope of various embodiments of the present invention. The microwave filter of the present application is described with reference to microstrip technology for which it is initially being used.
Reference is made to FIG. 1 which shows a conventional design for a microstrip bandpass filter 100 which comprises a plurality of vertical microstrip elements 102 placed parallel to one another and connected to one another by horizontal microstrip elements 104 . The upper ends 102 A of the elements 102 are open while the lower ends 102 B of the elements 102 are connected to ground. For example, the lower ends 102 B may be connected to a ground plane by vias represented by the round holes at the lower ends 102 B of the vertical elements 102 .
The filter 100 is tuned by selecting the length of each of the elements 102 , the points at which each horizontal microstrip element 104 is attached to each vertical element 102 and the lengths of the horizontal microstrip elements 104 , as well as the point of signal entry 106 and the point of signal exit 108 on each end of the filter 100 . The frequency response of one configuration of a filter as illustrated in FIG. 1 is shown in FIG. 2 where the filter defines a passband frequency range in the vicinity of 5 GHz.
As shown in FIG. 2 , the passband frequency range around 5 GHz is passed while lower and higher frequencies are rejected. As also shown in FIG. 2 , frequencies in the range of three times the desired frequency range, around 15 GHz are also passed, and this is a general property of almost all passband filter designs. The selectivity of the filter 100 can be decreased by the use of fewer elements and can be increased by the use of more elements, but the basic features of the frequency response would be similar. If the frequency band at around three times the desired frequency range needs to be suppressed by the nature of the circuit design in which the filter operates, additional filter circuitry would be needed to suppress these higher frequencies. The need for additional filter circuitry is generally true of bandpass filter designs, including the exemplary filter 100 and filters with gap-coupled elements.
It is also known to use a “spurline” in a microstrip circuit to create a notch filter. A spurline consists of a cut in the microstrip circuit shaped like an L having one end, the short leg of the L, open to one side of the microstrip circuit and the rest of the spurline cut, the long leg of the L, entirely contained within the microstrip circuit. With reference to FIG. 3 , if a spurline 300 is formed in a section of microstrip circuit 302 , signals of a specific frequency and frequencies around the specific frequency will be rejected to define the notch. With a spurline having a nominal length of ¼λ, microwave energy at the desired notch frequency λ fed into the microstrip circuit 302 at the left is rejected and does not exit from the right end of the microstrip circuit 302 . FIG. 4 shows a characteristic frequency response curve of the notch filter wherein odd harmonics of the desired notch frequency are also rejected.
In accordance with the teachings of the present application, by forming at least one spurline in at least one of the horizontal microstrip elements 104 of the bandpass filter 100 of FIG. 1 , a compact embodiment of a bandpass filter is created with at least one of the odd higher-order responses being reduced or at least one of the odd higher-order responses being substantially eliminated. An exemplary embodiment is shown in FIG. 5 wherein a bandpass filter 500 comprises a plurality of vertical microstrip elements 502 placed parallel to one another and connected to one another by horizontal microstrip elements 504 wherein each of the horizontal microstrip elements 502 includes a single spurline 506 . By including spurlines in each of the horizontal microstrip elements 504 , the third order response is maximally suppressed. Additional spurlines may be formed in one or more of the horizontal microstrip elements 504 to further reduce a given odd higher-order response or to at least partially suppress one or more additional odd higher-order responses.
In the illustrated embodiment of FIG. 5 , the upper ends 502 A of the elements 502 are open and the lower ends 502 B of the elements 502 are connected to ground. For example, the lower ends 502 B may be connected to a ground plane (not shown) located beneath the elements 502 using vias represented by the round openings at the lower ends 502 B of the vertical elements 502 . It is noted that the teachings of the present application are equally applicable to similar filter designs that have vertical microstrip elements that are open at both ends or grounded at both ends. While such filters would provide different filtering characteristics, use of the teachings of the present application would still reduce or eliminate a third or higher-order odd harmonic response if required for a given application.
The bandpass filter 500 is tuned by selecting the length of each of the elements 502 , the points at which each horizontal microstrip element 504 is attached to each vertical element 502 and the lengths of the horizontal microstrip elements 504 , as well as the point of signal entry 508 and the point of signal exit 510 on each end of the filter 500 . The band of frequencies, i.e., the suppressed higher-order odd response, that is rejected is tuned by appropriately sizing and shaping the spurlines 506 . As an example, the spurlines 506 may be sized and shaped to block the third harmonic or third order response of the filter 500 so that the lengths of the spurlines 506 are set to be about ¼λ where λ is the wavelength of the third harmonic of the center frequency of the passband.
As shown in FIG. 6 , a passband frequency range around 5 GHz is passed while lower and higher frequencies are rejected. Different from the frequency response of the filter 100 as shown in FIG. 2 , frequencies in the range of three times the desired frequency range, i.e., around 15 Ghz, are rejected. The selectivity of the filter 500 can be decreased by the use of fewer elements and can be increased by the use of more elements, but the basic features of the frequency response would be similar. Thus, using the teachings of the present application, the requirement that a desired range of frequencies is passed by a filter, while at the same time the frequency range at three times or a higher-order odd multiple of the desired frequency range is not passed by the filter is accomplished without the need of adding preceding or following filter circuitry, and without increasing the physical area occupied by the filter.
Having thus described the invention of the present application in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.
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A bandpass filter passes a range of frequencies with low loss while suppressing frequencies above and below the passed range of frequencies. One or more spurlines is included into the existing structure of the bandpass filter so that a selected odd multiple of the passed frequency range is suppressed.
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CROSS-REFERENCE STATEMENT
[0001] This Application claims the benefit of U.S. Provisional Application No. 60/193,626, filed Mar. 31, 2000.
FIELD OF THE INVENTION
[0002] This invention generally concerns a component and system used to build up permanent hardenable material walls in building construction. This invention particularly concerns a component and system that remains in place after a hardenable material, such as concrete, used to form the walls hardens. This invention more particularly concerns such a component and system wherein at least one, and preferably both, of the interior and exterior surfaces of the wall constitute a portion of the component.
BACKGROUND OF THE INVENTION
[0003] In North America, concrete wall fabrication typically entails several steps. First, construct form walls that establish a cavity or space. Second, pour concrete into the cavity or space. Third, allow the concrete to set or cure sufficiently to allow removal of the form walls. Fourth, remove the form walls.
[0004] In residential construction, concrete basement wall and other concrete wall fabrication employs the above procedure. After completing concrete wall fabrication, one then builds wood framing as required on top of the concrete walls, beside the concrete walls or both. A typical next step involves inserting insulation between wood framing members. After that, one then finishes the wall both inside and out.
[0005] The foregoing practices are time-consuming, inefficient, expensive and wasteful, particularly of materials and labor used to fabricate and then remove form walls. As common construction practices, especially in colder climates, dictate that all walls, including basement walls, be insulated, the need to remove form walls and then build and insulate wood frame walls delays subsequent building construction steps.
[0006] An alternate procedure, practiced for several years, particularly in Europe, combines a number of construction steps by using a foam insulating material to fabricate permanent form walls. Because the foam insulating material remains in place, no further insulation need be installed and finishing materials may be applied to interior and exterior walls as desired. This procedure works for both basement walls and above-ground walls.
[0007] U.S. Pat. No. 5,657,600 discloses a building component comprising first and second high density foam panels arranged in a spaced apart, parallel relationship to each other. At least two bridging members span the space between the panels and connect the panels to each other by being molded into the panels. Each bridging member has a pair of elongated end plates oriented vertically and abutting against outer surfaces of the foam panels. The bridging member may take on an X-shape and be fabricated from a plastic material such as high density, flame-retardant polyethylene, flame-retardant polypropylene, or polystyrene.
[0008] U.S. Pat. No. 4,730,422 discloses an insulating non-removable type concrete wall forming structure, device and system for attaching wall coverings thereto. In modular synthetic foamed plastic concrete form structures, a number of pairs of modular concrete impervious forming panels are stacked on top of each other and linked end to end. The panel pairs include vertically spaced rows of T-shaped tie slots into which T-shaped ends of synthetic plastic ties slideably fit. The outer surfaces of the slot sections have embossed tie-locator indicia thereon that enable fasteners to be screwed through the panel into the synthetic plastic ties to securely anchor exterior wall finishing covering to the panels or wall sections.
[0009] U.S. Pat. No. 4,889,310 discloses an improved concrete forming system that comprises a series of opposed first and second polystyrene foam panels connected in opposed, parallel, spaced-apart relationship. The foam panels have vertically aligned tie slots defined along their upper and lower edges. Plastic ties fit into the tie slots to hold the foam panels in their spaced-apart configuration. Each tie end has spaced-apart, T-shaped inner and outer paddle members that fit against, respectively, the inner and outer panel surfaces. The tie ends may be broken off after the concrete hardens if one desires to remove either or both of the foam panels. The ties may be modular in that they comprise tie ends and a spacer strap that can be lengthened or shortened as desired to vary the spacing between the foam panels.
[0010] U.S. Pat. No. 4,936,540 discloses ties for interlocking a pair of spaced-apart form panels such as foam panels. The ties have at least one beveled end that allows it to be forced through the foam panels without first cutting a tie slot. The ties may also have an integrally formed end plate opposite the beveled end. Once the beveled end passes through both spaced-apart foam panels, a spacer may be inserted between the panels to maintain proper alignment and a gusset plate fitted over the beveled end to hold the panels in place.
[0011] U.S. Pat. No. 5,107,648 discloses an insulated wall construction using tongue-and-groove foam boards held in a spaced-apart configuration by spacer rod assemblies. The spacer rod assemblies comprise an external support plate with a rod receiving segment that passes through the foam board, an internal support plate that slides over the rod receiving segment, a spacer rod that fits into rod receiving segments of both boards and locking pins that hold an end of the spacer rod in place within each rod receiving segment. The spacer rod may take on any of a number of configurations ranging from cylindrical (both solid and hollow), through shaped (other than cylindrical) to externally screw threaded. In the latter configuration, the rod receiving segments are internally screw threaded. The external support plates provide a foundation for covering material such as gypsum board and stucco.
SUMMARY OF THE INVENTION
[0012] The present invention is an insulated, wall form comprising a first panel segment, a second panel segment, and a plurality of connectors, the first panel segment and the second panel segment each being generally planar structures, the first and second panel segments being spaced apart from each other so as to constitute a cavity and oriented such that the first panel segment is generally parallel to the second panel segment, the connectors each having a first end and a second end that is remote from the first end, the first end being removably attached to the first panel segment and the second end being removably attached to the second panel segment, the plurality of connectors maintaining the first and second panel segments in a spaced apart generally parallel orientation, the wall form defining a cavity adapted to receive a hardenable filler material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] [0013]FIG. 1 is fragmented top-plan view of a portion of one embodiment of a panel segment.
[0014] [0014]FIG. 2 is a fragmented top-plan view of a portion of the embodiment shown in FIG. 1 together with a portion of a connector.
[0015] [0015]FIG. 3 is a horizontal cross-sectional view of an insulated wall form that includes two opposed panel segments of the type shown in FIG. 1 and a plurality of connectors.
[0016] [0016]FIG. 4 is a fragmented top-plan view of a portion of an alternate and preferred embodiment of a panel segment.
DETAILED DESCRIPTION OF THE INVENTION
[0017] [0017]FIG. 1 illustrates a portion of a wall panel segment 20 suitable for use as part of wall form 10 (shown in FIG. 3). Panel segment 20 is a laminar structure that includes inner layer 21 and outer layer 25 . Inner layer 21 has an inner surface 22 and a spaced-apart, generally parallel outer surface 23 . Inner layer 21 also has defined therein a plurality of passageways 24 that intersect and are in fluid communication with both the inner surface 22 and the outer surface 23 . Outer layer 25 has an inner surface 26 and a spaced-apart, generally parallel outer surface 28 . Outer layer 25 also has defined therein a plurality of slots 27 . Outer surface 23 of inner layer 21 and inner surface 26 of outer layer 25 are in operative contact with each other. Such operative contact desirably occurs by way of an adhesive material (not shown) disposed between surfaces 23 and 26 . Slots 27 , preferably T-shaped, are in fluid communication with passageways 24 of inner layer 21 . A combination of slots 27 and passageways 24 constitutes a plurality of channels that are adapted to receive connector ends (shown in FIGS. 2 and 3).
[0018] The channels in wall panel segment 20 , also referred to as a first panel segment, preferably comprise an elongated aperture in inner layer 21 , preferably a foam layer, and a cavity in outer layer 25 . The aperture and cavity are in fluid communication with each other. The cavity and the aperture each have a width. The width of the cavity is preferably greater than the width of the aperture. Such channels readily receive connectors such as connectors 30 shown in FIG. 2.
[0019] [0019]FIG. 2 illustrates a fragmentary section of wall panel segment 20 together with a fragmentary cross-section of a connector 30 . Connector 30 has a first end 31 and, spaced apart by way of center shaft 33 , a second end 35 (shown in FIG. 3). An intermediate portion of shaft 33 proximate to, but spaced apart from, each of ends 31 and 35 is externally screw-threaded. FIG. 2 shows screw-threaded segment 32 proximate to end 31 . Screw-threaded segment 34 (not shown) is proximate to, but spaced apart from, end 35 (shown only in FIG. 3). Internally screw-threaded compression fittings 36 threadably engage externally screw-threaded shaft portions 32 and 34 (not shown) so as to hold connector 30 in a fixed position relative to wall panel segments 20 and 40 (shown in FIG. 3).
[0020] Although not shown in FIGS. 2 and 3, wall panel segments 20 and 40 preferably further comprise a sealing means that is disposed between a connector end, such as first end 31 of connector 30 , and its associated compression fitting or nut 36 such that the sealing means is in operative or sealing contact with both the inner foam layer 21 of panel segment 20 or inner foam layer 41 of panel segment 40 , whichever is appropriate, and compression nut 36 .
[0021] Skilled artisans readily recognize that a variety of substitutes may serve the same purpose as the combination of externally screw-threaded shaft segments 32 and 34 and internally screw-threaded compression fittings 36 . By way of example only and without limit, such substitutes include one or more projections from the shaft over which a collar slides, then twists and locks or a series of rings on the shaft over which a collar with internally defined ridges or lock means slides and then stays in position. Skilled artisans also recognize that compression fittings 36 and any of the alternatives need not be solid or continuous shapes. In fact, for ease of installation, the fittings preferably have a slot that communicates between an external edge of the fitting and a central aperture of the fitting such as the internally screw-threaded portion of fittings 36 . The slot allows the fitting to slide onto the center shaft 33 of connector 30 at a field or assembly site.
[0022] [0022]FIG. 3 illustrates wall form 10 . Form 10 comprises wall segment 20 , wall panel segment 40 and a plurality of linked connectors 30 . Wall panel segment 40 may be, and preferably is, a mirror-image of wall segment 20 save for the material from which outer layers 25 and 45 are fabricated. Accordingly, wall panel segment 40 is a laminar structure that includes inner layer 41 and outer layer 45 . Inner layer 41 has an inner surface 42 and a spaced-apart, generally parallel outer surface 43 . Inner layer 41 also has defined therein a plurality of passageways 44 that intersect and are in fluid communication with both the inner surface 42 and the outer surface 43 . Outer layer 45 has an inner surface 46 and a spaced-apart, generally parallel outer surface 48 . Outer layer 45 also has defined therein a plurality of slots 47 . Outer surface 43 of inner layer 41 and inner surface 46 of outer layer 45 are in operative contact with each other. Such operative contact desirably occurs by way of an adhesive material (not shown) disposed between surfaces 43 and 46 . Slots 47 , preferably T-shaped, are in fluid communication with passageways 44 of inner layer 41 . Like the combination of slots 27 and passageways 24 shown in FIG. 1, a combination of slots 47 and passageways 44 yields a plurality of channels that are adapted to receive connector ends (shown in FIGS. 2 and 3).
[0023] The channels in wall panel segment 40 , also referred to as a second panel segment, preferably comprise an elongated aperture in inner layer 41 , preferably a foam layer, and a cavity in outer layer 45 . As with their counterparts in layers 21 and 25 , the aperture and cavity are in fluid communication with each other and each has a width with the width of the cavity preferably being greater than that of the aperture. The channels are preferably adapted to receive connector ends such as those of connectors 30 shown in FIGS. 2 and 3.
[0024] The connectors, such as connectors 30 , are preferably disposed in a number of connector assemblies. Each connector assembly more preferably comprises a lattice wherein each connector is oriented so as to be spaced apart from and generally parallel to at least one other connector. The orientation is desirably maintained by way of at least one connector link between each of two adjacent connectors within a connector assembly. As shown in FIG. 3, the plurality of connectors 30 are linked together or interconnected by way of a plurality of links 32 . FIG. 3 shows two links 32 between each pair of connectors 30 . While two links 32 per pair of connectors 30 yield very satisfactory results in terms of simplicity and spacing uniformity, one may use a greater or lesser number of links without departing from the scope or spirit of the invention. In fact, one may eliminate the links altogether if so desired. The links 32 may be flexible to accommodate storage and handling before use as part of wall form 10 . Links 32 may also be rigid to provide additional stability before disposing a hardenable material into a cavity formed by inner surfaces 22 (FIG. 1) and 42 of corresponding panel segments 20 and 40 .
[0025] Ends 31 and 35 of connectors 30 may take on any of a variety of shapes without departing from the spirit and scope of the present invention. The shape simply needs to accommodate a slideable engagement with at least a portion of slots 27 (FIG. 2) and 47 of corresponding panel segments 20 and 40 . The shape desirably provides frictional, but slideable engagement with surfaces of slots 27 and 47 . Shapes include, for example, squares, rectangles, parallelograms, trapezoids, polygons (e.g. hexagons and octagons), circles and ellipses. While the shapes preferably have a thickness that is at least equal to the width of slots 27 and 47 , they more preferably have a thickness that slightly exceeds that width in order to provide a good friction fit.
[0026] A particularly preferred connector is a foldable connector such as that disclosed in U.S. Design Pat. No. 383,373, U.S. Pat. No. 4,706,429, U.S. Pat. No. 4,730,422 and U.S. Pat. No. 4,885,888. The relevant teachings of the four patents are incorporated herein by reference. By using such connectors, one can assemble the insulated wall form of the present invention and then collapse or fold it about the connectors into a flattened configuration for shipping or transport. When ready for use at a job site, one can simply unfold it about the connectors and set it into place.
[0027] [0027]FIG. 4 shows an alternate preferred embodiment of a panel segment designated by reference numeral 20 ′. Panel segment 20 ′ differs from panel segment 20 in that outer layer 25 ′ has no slots defined therein whereas outer layer 25 has slots 27 defined therein. Like segment 20 , segment 20 ′ is a laminar structure that includes inner layer 21 ′ and outer layer 25 ′. Inner layer 21 ′ has an inner surface 22 ′ and a spaced-apart, generally parallel outer surface 23 ′. Inner layer 21 ′ also has defined therein a plurality of passageways 24 ′ that intersect and are in fluid communication with both the inner surface 22 ′ and the outer surface 23 ′. Passageways 24 ′ preferably have a T-shape similar to that provided by a combination of passageways 24 and slots 27 of panel 20 . Although FIG. 4 shows passageways 24 ′ as being located proximate to or intersecting with outer surface 23 ′ of inner layer 21 ′, passageway may also be displaced toward inner surface 22 ′ so that it a) is entirely located within inner layer 21 ″, b) intersects only with inner surface 22 ′ and c) is in fluid communication only with inner surface 22 ′. Outer layer 25 ′ has an inner surface 26 ′ and a spaced-apart, generally parallel outer surface 28 ′. Outer surface 23 ′ of inner layer 21 ′ and inner surface 26 ′ of outer layer 25 ′ are in operative contact with each other. As with panel 20 , such operative contact desirably occurs by way of an adhesive material (not shown) disposed between surfaces 23 ′ and 26 ′.
[0028] T-shaped passageways 27 and 24 ′ may be fabricated by any suitable means. For example, one may use a router or other similar device to cut the passageways after placing inner layer 21 ′ and outer layer 25 ′ in operative contact with each other. A more preferred technique uses narrow (relative to outer layer 25 ′) strips of inner layer 21 ′. The outer surface 23 ′ of inner layer 21 ′ has defined therein a longitudinal step or shoulder on each side such that when two strips of inner layer 21 ′ are placed proximate to, but not in physical contact with, each other, they define a T-shaped passageway 24 ′.
[0029] Outer panel 40 may be, and preferably is, modified in the same manner as inner panel 20 to yield an outer panel 40 ′ (not shown). Similarly, an alternate and preferred wall form 10 ′ includes inner panels 20 ′ and outer panels 40 ′ in place of inner panels 20 and outer panels 40 . One may, of course, mix and match the panels to provide, for example an inner panel 20 and an outer panel 40 ′, two inner panels 20 , 20 ′ or a combination of one panel 20 and one panel 20 ′, or two outer panels 40 , 40 ′ or a combination of one panel 40 and one panel 40 ′ depending upon factors such as design choice and wall location.
[0030] Inner panels 20 and 20 ′ are laminar structures that comprise at least two layers, an inner layer that comprises an insulating foam material and an outer layer that comprises an interior surface material. The interior surface material is selected from gypsum board, wallboard, wood, paneling, brick, fiberboard, vinyl boards or any other material that provides acceptable aesthetic performance, functional performance or both.
[0031] Outer panels 40 and 40 ′ are laminar structures that comprise at least two layers, an inner layer that comprises an insulating foam material and an outer layer that comprises an exterior surface material. The exterior surface material is selected from wood, brick, stucco, concrete block, cementitious board laminate, fiberboard, vinyl siding, wood laminates, brick veneer, or any other material that provides acceptable functional performance and, desirably, aesthetic appeal.
[0032] The insulating foam material may be any cellular insulating material that is rigid enough to substantially maintain its shape during the construction and use of the wall form. Preferably, the insulating foam panel is a cellular polymeric foam. It may be made from a thermosetting or thermoplastic polymer. Suitable polymers include polyethylene (including low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE) and substantially linear ethylene interpolymers), polypropylene, polyurethane, polyisocyanurate, ethylene-vinyl acetate copolymers, polyvinyl chloride, phenol-formaldehyde resins, ethylene-styrene interpolymers and alkenyl aromatic polymers and copolymers, including those derived from alkenyl aromatic compounds such as styrene, alphamethylstyrene, ethylstyrene, vinyl benzene, vinyl toluene, chlorostyrene, and bromostyrene. A preferred alkenyl aromatic polymer is polystyrene. Minor amounts of monoethylenically unsaturated compounds such as C 2-6 alkyl acids and esters, ionomeric derivatives, and C 4-6 dienes may be copolymerized with alkenyl aromatic compounds. Examples of copolymerizable compounds include acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, itaconic acid, and acrylonitrile. Blends of any two or more of the foregoing or blends of any of the foregoing with another polymer or resin are suitable. Rigid polyurethane, polystyrene, polyisocyanurate and phenolic foams are preferred, with polystyrene and polyisocyanurate foams being especially preferred. The foams may be used as is or they may have an external surface mechanically modified. Mechanical modification includes operations such as sanding, scraping, planing or any other action that alters the external surface from its as-formed state.
[0033] Suitable alkenyl aromatic polymers include those derived from alkenyl aromatic compounds such as styrene, alphamethylstyrene, ethylstyrene, vinyl benzene, vinyl toluene, chlorostyrene, and bromostyrene. A preferred alkenyl aromatic polymer is polystyrene. Minor amounts of monoethylenically unsaturated compounds such as C 2-6 alkyl acids and esters, ionomeric derivatives, and C 4-6 dienes may be copolymerized with alkenyl aromatic compounds. Examples of copolymerizable compounds include acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, itaconic acid, acrylonitrile, maleic anhydride, methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, methyl methacrylate, vinyl acetate and butadiene. Preferred foams comprise substantially (i.e., greater than 95 percent) and most preferably entirely of polystyrene.
[0034] Any conventional process may prepare insulating foam materials, with extrusion foaming being preferred.
[0035] In order to ease fabrication of wall forms 10 and 10 ′ as well as decrease assembly time thereof, one may dispose a lubricating material on surfaces of connector ends 31 and 35 that will come in contact with slots 27 and 47 of wall panel segments 20 and 40 or slots 24 ′ and 44 ′ (not shown) of wall panel segments 20 ′ and 40 ′. Suitable lubricating materials include mineral oils, synthetic oils and fluorocarbons.
[0036] Wall forms 10 and 10 ′ define a cavity designed to accommodate and shape a load-bearing material, preferably a hardenable material such as concrete, fiber-reinforced concrete or rebar-reinforced concrete. If desired, the cavity may further comprise a cavity liner. The cavity liner, when used, is adjacent to and in physical contact with at least a surface portion of the inner surfaces of the selected combination of inner and outer panels 20 , 20 ′, 40 and 40 ′. The inner and outer surfaces are, respectively, 22 , 22 ′, 42 and 42 ′ (not shown). The cavity liner comprises a film made of a thermoplastic polymer that is a polyolefin such as polypropylene, low density polyethylene, high density polyethylene or linear low density polyethylene, a polyamide, an alkenyl aromatic polymer such as polystyrene, a poly(vinyl chloride), a polycarbonate, an acrylic polymer, or a polyester. The film may be non-oriented, uniaxially oriented or biaxially oriented. The film may contain one or more conventional additives such as fillers, pigments, colorants, antioxidants, ultraviolet light stabilizers, fire retardant materials (it being recognized that all organic materials will bum under the right conditions), and process aids.
[0037] Any load-bearing material may be used that will provide adequate strength and rigidity. In simpler or less expensive wall constructions, the load-bearing material can be, for instance, wood, stone, dirt, sand, metal, and the like. These are advantageously used in a particulate form so they can be readily poured into the form assemblage as a loose fill. However, this invention is particularly adapted for use with a load-bearing material that is poured into place after the system of wall panels, insulating foam panels and panel connectors is assembled, and then hardened. Accordingly, any of the many forms of cement such as Portland cement, aluminous cement and hydraulic cements are suitable, as are hardenable clays such as adobe, mortar, and hardenable mixtures of clays and cement. It is generally preferred for reasons of cost and properties to use concrete, which is an aggregate of a material such as gravel, pebble, sand, broken stone, slag, or cinders, in a hardenable matrix, usually mortar or a form of cement such as Portland, aluminous or hydraulic cement. Generally, any concrete or aggregate that is useful in preparing load-bearing building walls is suitable for use with this invention.
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Insulated wall forms that remain in place and include an exterior wall covering such as stucco or a brick facade, an interior wall covering such as gypsum board or both an exterior wall covering and an interior wall covering greatly simplify wall construction using a hardenable material such as concrete and reduce steps needed to put a finished wall in place.
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FIELD OF THE INVENTION
This invention is an improvement in a process for the production of alkylated aromatic compounds.
BACKGROUND OF THE INVENTION
Nearly forty years ago, it became apparent that household laundry detergents made of branched alkylbenzene sulfonates were gradually polluting rivers and lakes. Solution of the problem led to the manufacture of detergents made of linear alkylbenzene sulfonates (LABS), which were found to biodegrade more rapidly than the branched variety. Today, detergents made of LABS are manufactured worldwide.
LABS are manufactured from linear alkyl benzenes (LAB). The petrochemical industry produces LAB by dehydrogenating linear paraffins to linear olefins and then alkylating benzene with the linear olefins in the presence of HF. The linear paraffins are straight chain (unbranched) or normal paraffins. Normally, the linear paraffins are a mixture of linear paraffins having different carbon numbers. The linear paraffins have generally from about 6 to about 22, preferably from 10 to 15, and more preferably from 10 to 12 or from 11 to 13, carbon atoms per molecule.
A preferred method of production of the linear paraffins is the extraction of straight chain hydrocarbons from a hydrotreated kerosene boiling range petroleum fraction. The kerosene boiling range fraction contains a mixture of different hydrocarbons, including mostly paraffinic and aromatic hydrocarbons, but containing also olefinic and naphthenic hydrocarbons. The kerosene boiling range fraction is usually defined as comprising a fraction having a boiling range of from about 300° F. (149° C.) to about 572° F. (300° C.). The initial boiling point of the kerosene boiling range fraction may vary from about 300 to about 374° F. (149 to 190° C.) and the final boiling point may vary from about 455 to about 572° F. (235 to 300° C.). The kerosene boiling range generally includes hydrocarbons having from about 8 to about 17 carbon atoms.
The kerosene boiling range fraction is generally produced by fractionating crude oil. Crude oil is the liquid part, after being freed from dissolved gas, of petroleum, a natural organic material composed principally of hydrocarbons that occur in geological traps. Being derived from a natural material, crude oils vary in composition depending on where the petroleum occurred and other factors. Commercial oil refineries typically receive crude oil from many different sources, and the composition of the crude oil that is charged to the crude oil fractionation unit changes frequently. The paraffinic and aromatic hydrocarbons that make up the bulk of a kerosene boiling range fraction can change as different crude oils are processed in the crude oil fractionation unit. It is common for the volumetric flow rate of the kerosene boiling range fraction to fluctuate by up to 30 vol-% or more, for a given boiling point range of the kerosene boiling range fraction produced from a crude oil fractionation unit. Because such fluctuations in flow rate can make it difficult to control downstream units that process the kerosene boiling range fraction, the operator of a crude oil fractionation unit may intentionally adjust the initial and final boiling points of the kerosene boiling range fraction as permissible within the above mentioned ranges and thereby achieve a more constant flow rate of the kerosene boiling range fraction. It is also common for the kerosene boiling range fraction to fluctuate between liquid phase and a mixture of vapor and liquid phases, since the proportion of vapor phase depends on both the composition of the kerosene boiling range fraction and its temperature, which can also vary. For a given temperature, the lighter the kerosene boiling range fraction, the greater is the proportion in the vapor phase. Accordingly, in commercial practice the composition, the amount, the boiling range and/or the phase of the kerosene boiling range fraction recovered from a commercial crude oil fractionation unit often fluctuate daily, or even hourly.
In order to produce LAB having, for example, from 11 to 13 carbon atoms per linear alkyl group, a stream of linear paraffins comprising C 11 to C 13 hydrocarbons is desired. A suitable stream is a heartcut of the kerosene boiling range fraction suffices, provided that hydrocarbons boiling lower than C 11 linear paraffins and hydrocarbons boiling higher than C 13 linear paraffins must be removed from the kerosene fraction. Generally, this heartcut is produced in a two-step, strip-and-rerun fractionation process. First, the kerosene fraction is introduced into a fractionation column, called a stripper column, which strips overhead the C 10 − hydrocarbons from the kerosene feedstock, producing a bottom stream comprising C 11 + hydrocarbons. Then, the bottom stream is introduced into a second fractionation column, called a rerun column, which boils overhead the C 11 to C 13 hydrocarbons as a heartcut and produces a bottom stream comprising C 14 + hydrocarbons. In some commercial units, the overhead condenser of the second fractionation column is a contact condenser. This heartcut is then hydrotreated, and the straight chain hydrocarbons are extracted from the hydrotreated fraction, thereby producing the linear paraffin stream.
Alkylaromatic processes that use the two-step, strip-and-rerun fractionation process to produce the heartcut are inefficient, since they require relatively large amounts of utilities. Thus, alkylation processes are sought in which the heartcut is produced in a more efficient manner that uses fewer utilities than the prior art process.
Over fifty years ago, Wright proposed replacing two distillation columns with a single distillation column having a vertical partition (dividing wall column) within the column that would effect the separation of the column feed into three constituent fractions. It was recognized then that a dividing wall column could minimize the size or cost of the equipment needed to produce overhead, bottoms, and sidedraw products. See U.S. Pat. No. 2,471,134 (Wright). Wright described using the dividing wall column to separate a mixture of ethane, propane, butanes, and a small amount of C 5 and heavier hydrocarbons.
Since then, researchers have studied the dividing wall column and have proposed using dividing wall columns for separating other mixtures, including xylenes (Int. Chem. Engg., Vol. 5, No. 3, July 1965, 555-561); butanes and butenes (See e.g., Trans IChemE, Vol.70, Part A, March 1992, 118-132); methanol, isopropanol, and butanol (See e.g., Trans IChemE, Vol. 72, Part A, September 1994, 639-644); ethanol, propanol, and butanol (Ind. Eng. Chem. Res. 1995, 34, 2094-2103); air (See e.g., Ind. Eng. Chem. Res. 1996, 35, pages 1059-1071); natural gas liquids (Chem. Engg., July 1997, 72-76); and benzene, toluene, and ortho-xylene (Paper No. 34 K, by M. Serra et al., prepared for presentation at the AlChE Meeting, Los Angeles, Calif., U.S.A., November 1997). The Serra et al. paper also describes separating mixtures of butanes and pentane; pentanes, hexane, and heptane; and propane and butanes.
Despite the advantages of the dividing wall column and despite much research and study, the processing industry has long felt reluctant to use dividing wall columns in commercial processes. This widespread reluctance has been attributed to various concerns, including control problems, operational problems, complexity, simulation difficulties, and lack of design experience. See, for example, the articles by C. Triantafyllou and R. Smith in Trans IChemE, Vol. 70, Part A, March 1992, 118-132; F. Lestak and C. Collins in Chem. Engg., July 1997, 72-76; and G. Duennebier and C. Pantelides in Ind. Eng. Chem. Res. 1999, 38, 162-176. The article by Lestak and Collins sets forth some general guidelines and considerations when substituting a dividing wall column for conventional columns. Nevertheless, the literature documents relatively few practical uses of dividing wall columns in commercial plants. See the article by H. Rudd in The Chemical Engineer, Distillation Supplement, Aug. 27, 1992, s14-s15 and the article in European Chemical News, Oct. 2-8, 1995, 26.
Prior art alkylaromatic processes, in particular, do not use dividing wall distillation columns. Nor do they use fully thermally coupled distillation columns, which as explained in the above-mentioned article by C. Triantafyllou and R. Smith, are thermodynamically equivalent to dividing wall columns when there is no heat transfer across the dividing wall. In particular, a dividing wall distillation column has not been used for producing the heartcut from the kerosene boiling range fraction. This is not only for the reasons given above but also for three additional reasons. First, the focus of prior research studies has been on separating relatively unchanging mixtures of only a few (e.g., 3 to 5) components, whereas the kerosene boiling range fraction is a seemingly ever-changing mixture of hundreds or thousands of hydrocarbons. Second, the research studies produce dividing wall distillation product streams containing usually only one component, whereas the heartcut, stripper overhead stream, and rerun bottom stream contain many hydrocarbon components. Third, product specifications for LAB require that the heartcut composition be controlled relatively tightly, since the detergent properties of the linear alkylbenzene sulfonates (LABS) depend in large part on the particular paraffin isomers in the heartcut. Thus, alkylaromatic processes are characterized by both an ever-changing composition of a complex kerosene mixture and a relatively tight specification on a complex mixture of paraffins in the heartcut. This combination compounds the problems, difficulties, and complexity of using a dividing wall distillation column or two fully thermally coupled distillation columns.
SUMMARY OF THE INVENTION
This invention is a process for the production of alkylaromatic hydrocarbons by alkylating feed aromatic hydrocarbons with linear olefinic hydrocarbons, where the linear olefinic hydrocarbons are produced by dehydrogenating linear paraffinic hydrocarbons, where the linear paraffinic hydrocarbons are extracted from a heartcut, and where the heartcut is fractionated from a kerosene fraction in either a dividing wall fractionation column or in two fully thermally coupled fractionation columns, where the two fully thermally coupled fractionation columns are a prefractionator and a main column. It has now been recognized that use of two fully thermally coupled fractionation columns or of a dividing wall fractionation column produces the heartcut in a manner that is stable and controllable for commercial LAB production, despite the complexity of the mixture of hydrocarbons in commercial kerosene fractions and despite the fluctuations in the compositions of those fractions. In addition, use of two fully thermally coupled fractionation columns or the dividing wall fractionation column reduces significantly the cost of utilities in producing the heartcut. In a preferred embodiment of this invention, the two fully thermally coupled fractionation columns or the dividing wall fractionation column is integrated with the paraffin recycle fractionation column and/or the LAB product fractionation column, thereby further decreasing the cost of utilities for producing LAB. As between a single dividing wall fractionation column on the one hand and two fully thermally coupled fractionation columns on the other hand, the former is preferred when the cost of a single fractionation vessel represents a significant savings over that of two fractionation vessels.
Accordingly, in a broad embodiment, this invention is a process for the production of alkylaromatics. A feed stream comprising low-boiling hydrocarbons, heartcut hydrocarbons, and high-boiling hydrocarbons passes into a first lateral section of an intermediate portion of a fractionation column at fractionation conditions. The entering compounds are separated to provide an overhead stream comprising the low-boiling hydrocarbons, a sidedraw stream comprising the heartcut hydrocarbons, and a bottom stream comprising the high-boiling hydrocarbons. The first lateral section is separated from a second lateral section of the fractionation column by a vertically oriented baffle extending upward from a lower portion of the fractionation column to an upper portion of the fractionation column. The overhead stream is at least partially condensed to form a condensed stream comprising the low-boiling hydrocarbons, and a portion of the condensed stream is refluxed to the fractionation column. The low-boiling hydrocarbons are recovered from the overhead stream. Heat is introduced to the lower portion of the fractionation column, and a bottom stream comprising the high-boiling hydrocarbons is withdrawn from the lower portion of the fractionation column. The high-boiling hydrocarbons are recovered from the bottom stream. A sidedraw stream comprising the heartcut hydrocarbons comprising paraffinic hydrocarbons is withdrawn from the second lateral section of the fractionation column. At least a portion of the sidedraw stream passes to a dehydrogenation zone to dehydrogenate the paraffinic hydrocarbons to monoolefinic hydrocarbons. A dehydrogenation zone effluent stream comprising the monoolefinic hydrocarbons is recovered from the dehydrogenation zone. At least a portion of the dehydrogenation zone effluent stream and an aromatic stream comprising a feedstock aromatic compound pass to an alkylation zone. The alkylation zone is operated at alkylation conditions to alkylate the feedstock aromatic compound with the monoolefinic hydrocarbons to produce alkylaromatic hydrocarbons. An alkylation effluent stream comprising the alkylaromatic hydrocarbons is recovered from the alkylation zone.
In another broad embodiment, this invention is a process for the production of alkylaromatics. A feed stream comprising low-boiling hydrocarbons, heartcut hydrocarbons, and high-boiling hydrocarbons passes into a prefractionator fractionation column which separates the entering hydrocarbons to provide a prefractionator overhead vapor stream comprising the low-boiling hydrocarbons and the heartcut hydrocarbons and a prefractionator bottom liquid stream comprising the high-boiling hydrocarbons and the heartcut hydrocarbons. At least a portion of the prefractionator overhead vapor stream passes to a main fractionation column, which is fully thermally coupled to the prefractionator fractionation column. At least a portion of the prefractionator bottom liquid stream passes to the main fractionation column. Hydrocarbons are separated in the main fractionation column. The following five streams are recovered from the main fractionation column: a main column overhead stream comprising the low-boiling hydrocarbons, a main column bottom stream comprising the high-boiling hydrocarbons, a main column product sidedraw stream comprising the heartcut hydrocarbons, a main column upper sidedraw stream comprising the low-boiling hydrocarbons and the heartcut hydrocarbons, and a main column lower sidedraw stream comprising the heartcut hydrocarbons and the high-boiling hydrocarbons. At least a portion of the main column upper sidedraw stream passes to the prefractionator fractionation column. At least a portion of the main column lower sidedraw stream passes to the prefractionator fractionation column. The main column overhead stream is at least partially condensed to form a condensed stream comprising the low-boiling hydrocarbons. A portion of the condensed stream is refluxed to the main fractionation column. Low-boiling hydrocarbons are recovered from the main column overhead stream. Heat is introduced to a lower portion of the main fractionation column, the high-boiling hydrocarbons are recovered from the main column bottom stream. At least a portion of the main column product sidedraw stream passes to a dehydrogenation zone, where the paraffinic hydrocarbons are dehydrogenated to monoolefinic hydrocarbons. A dehydrogenation zone effluent stream comprising the monoolefinic hydrocarbons is recovered from the dehydrogenation zone. At least a portion of the dehydrogenation zone effluent stream and an aromatic stream comprising a feed aromatic hydrocarbon pass to an alkylation zone operated at alkylation conditions to alkylate the feed aromatic hydrocarbon with the monoolefinic hydrocarbons to produce an alkylation effluent stream comprising alkylaromatic hydrocarbons. The alkylaromatic hydrocarbons are recovered from the alkylation effluent stream.
Other embodiments of the invention are set forth in the detailed description of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1-3 are process flow diagrams, each depicting an embodiment of the invention.
INFORMATION DISCLOSURE
U.S. Pat. No. 2,471,134 (Wright) discloses a vertical fractionation column having a vertical partition that separates the feed inlet and a side stream outlet.
The article by C. Triantafyllou and R. Smith in Trans IChemE, Vol. 70, Part A, March 1992, starting at page 118 explains that a dividing wall distillation column is thermodynamically equivalent to a fully thermally coupled distillation column, provided that there is no heat transfer across the dividing wall.
The paper entitled LAB Production , by R. C. Schulz, P. R. Pujado, and B. V. Vora, presented at the 2 nd World Conference on Detergents, held at Montreux, Switzerland, during Oct. 5-10, 1986, describes an LAB process wherein feed treatment of the kerosene consists of prefractionation using a stripper and a rerun column followed by hydrotreating of the kerosene heartcut. The teachings of the Schulz et al. article are incorporated herein by reference. LAB processes are further described in the book edited by Robert A. Meyers entitled Handbook of Petroleum Refining Processes , (McGraw-Hill, New York, Second Edition, 1997) at Chapter 1.5, the teachings of which are incorporated herein by reference. Paraffin dehydrogenation processes are described in the Meyers book in Chapter 5.2, the teachings of which are incorporated herein by reference.
U.S. Pat. No. 4,587,370 (DeGraff) discloses a fractionation method that uses three fractionation columns employed in series for recovering product alkylaromatics produced by alkylation of feed aromatics. The overhead stream of the second column contains the product alkylaromatics and is employed as the heat source for the reboiler of the first column, which recycles feed aromatics to the alkylation reactor.
The book entitled “Petroleum Refinery Engineering,” written by W. L. Nelson, and published by McGraw-Hill Book Company, Inc., New York, First Edition, Fourth Impression, 1936, page 442, FIG. 141, shows a method of removing reflux heat using circulating reflux.
The book entitled, “Petroleum Refinery Distillation,” written by R. N. Watkins, and published by Gulf Publishing Company, Book Division, Houston, Tex., Second Edition, May, 1981, pages 101-103 and 114-115, describes vacuum towers with pumpback and pumparound reflux heat removal.
The article written by Victor Briones, et al., which was published in Oil and Gas Journal, Jun. 21, 1999, beginning at page 41, describes using a pinch analysis method to design heat integration between atmospheric and vacuum units in a crude oil unit.
DETAILED DESCRIPTION
The feed to this invention is a kerosene boiling range fraction. A preferred feed has an initial boiling point of from about 311° F. to about 374° F. (155 to 190° C.) and a final boiling point of from about 455° F. to about 520° F. (235 to 271° C.). Preferred hydrocarbons in the feed have from about 10 to about 15 carbon atoms. The content of the normal paraffins, a desirable component of the feed when producing LAB, can vary generally from about 15 to about 35 vol-% of the feed, but is preferably greater than 20 vol-% and more preferably greater than 25 vol-%. The feed is preferably a two-phase, vapor-liquid mixture comprising from about 5 to about 30 mol-% vapor phase. The temperature of the feed is generally from about 365 to about 430° F. (185 to 221° C.), and preferably from about 400 to about 420° F. (204 to 216° C.).
The description that follows is written in terms of fractionating a feed stream of hydrocarbons into a light stream comprising low-boiling hydrocarbons, a sidedraw or product stream comprising heartcut hydrocarbons, and a heavy stream comprising high-boiling hydrocarbons. Low-boiling hydrocarbons generally have a lower boiling point than the heartcut hydrocarbons and typically contain at least one fewer carbon atom than the heartcut hydrocarbons. High-boiling hydrocarbons generally have a higher boiling point than the heartcut hydrocarbons and typically contain at least one more carbon atom than the heartcut hydrocarbons. The feed stream typically has a concentration of low-boiling hydrocarbons of more than 5 wt-%, a concentration of heartcut hydrocarbons of more than 50 wt-%, and a concentration of high-boiling hydrocarbons of more than 5 wt-%.
The light stream, the sidedraw stream, and the heavy stream are fractions defined by their boiling range, since each fraction contains tens, hundreds, or more components. The light stream is a stream in which generally at least 50 vol-%, and typically at least 75 vol-%, of the stream lies within the boiling range of from 240° F. (116° C.) to 340° F. (171° C.). At least 50 vol-%, and typically at least 75 vol-%, of the sidedraw stream lies within the boiling range of from 360° F. (182° C.) to 460° F. (238° C.). For the heavy stream, at least 50 vol-%, and typically at least 75 vol-%, of the stream lies within the boiling range of from 470° F. (243° C.) to 850° F. (454° C.). These boiling ranges are determined by ASTM Method D-86, and the vol-%'s are measured as a liquid. In producing these fractions, this invention is in contrast to the distillation research studies of the prior art, where the streams produced by the distillation usually contain one or a small number of components which are usually measured individually. As used herein, the term “fractionation” thus is used to refer to separation into boiling range fractions such as these, whereas the term “distillation” is used to refer to the prior art's separation of a stream into a small number of components. The arrangement of the dividing wall fractionation column and any associated equipment and its operating conditions (e.g., temperatures and vapor/liquid ratios) in the description that follows will be those generally associated with accomplishing such a separation in accordance with this invention, and are not intended to limit the scope of the invention as set forth in the claims.
A common example of a separation that can be accomplished using the subject invention is the separation of a feed comprising C 9 to C 15 hydrocarbons into a light stream comprising low-boiling hydrocarbons comprising C 9 and C 10 hydrocarbons, a sidedraw stream comprising heartcut hydrocarbons comprising C 11 C 12 , and C 13 hydrocarbons, and a heavy stream comprising high-boiling hydrocarbons comprising C 14 and C 15 hydrocarbons. In this example, the light key component, which is the lightest component in the sidedraw stream, is typically normal C 11 paraffin, and the heavy key component, which is the heaviest component in the sidedraw stream, is typically normal C 13 paraffin. If the feed also contains hydrocarbons lighter than C 9 hydrocarbons, then the low-boiling hydrocarbons can also comprise hydrocarbons lighter than C 9 hydrocarbons. If the feed contains hydrocarbons heavier than C 15 hydrocarbons, then the high-boiling hydrocarbons can comprise other hydrocarbons heavier than C 14 hydrocarbons in addition to the C 15 hydrocarbons. Another example is the separation of a feed comprising hydrocarbons lighter than C 8 hydrocarbons, C 8 to C 15 hydrocarbons, and hydrocarbons heavier than C 15 hydrocarbons. Using this invention, a light stream comprising low-boiling hydrocarbons comprising C 9 and lighter hydrocarbons, a sidedraw stream comprising heartcut hydrocarbons comprising C 10 , C 11 , and C 12 hydrocarbons, and a heavy stream comprising high-boiling hydrocarbons comprising C 13 and heavier hydrocarbons can be produced. Typically, in this case, the light key component is normal C 10 paraffin and the heavy key component is normal C 12 paraffin.
Despite fluctuations in the flow rate, composition, and phases of the feed, it has now been recognized that, when producing LAB, two fully thermally coupled fractionation columns or a dividing wall fractionation column is suitable for producing the heartcut fraction from the feed. Since the capital cost of a single new dividing wall fractionation column is generally less than that of two new fully thermally coupled fractionation columns, the use of a dividing wall fractionation column will be described first, followed by a description of the use of two fully thermally coupled fractionation columns.
When using a dividing wall fractionation column, the heartcut fraction is withdrawn from the dividing wall fractionation column in a sidedraw stream. The dividing wall fractionation column also produces an overhead stream comprising hydrocarbons that have lower boiling points than hydrocarbons in the sidedraw stream and a bottom stream comprising hydrocarbons having higher boiling points than hydrocarbons in the sidedraw stream. The dividing wall fractionation column has one inlet for the feed and three outlets, one outlet for each of the overhead stream, the sidedraw stream, and the bottom stream.
The dividing wall fractionation column has three fractionation zones, a top zone, a middle zone, and a bottom zone. The middle zone contains a dividing wall, the plane of which is vertically oriented. As used herein, the phrase “vertically oriented” means forming an angle with the horizontal of generally between about 85 and about 95 degrees, and preferably between about 87.5 and 92.5 degrees. The longitudinal axis of the middle zone is also generally vertical, as are the longitudinal axes of the top and bottom zones. The dividing wall divides the middle zone into two portions, a feed-side portion and a sidedraw-side portion. Neglecting the areas occupied by the thickness of the dividing wall and the thickness of the column walls, the area of any horizontal cross-section of the column is thus divided between the feed-side portion and the sidedraw-side portion. The division of the column's horizontal cross-section between these two portions is not necessarily equal. The division depends on the composition of the feed and on the proportion of the feed that is in the vapor phase. The area of the feed-side portion is generally from about 20% to about 80%, and preferably from about 35% to about 45% of the area of any horizontal cross-section. Accordingly, the area of the sidedraw-side portion is generally from about 20% to about 80%, and preferably from about 55% to about 65% of the area of any horizontal cross-section.
The dividing wall is generally a baffle that is preferably imperforate. The dividing wall may be a single piece or may consist of multiple sectional pieces that are affixed together, such as by welding or bolting. The baffle is generally rectangular having two faces and four edges. One face of the baffle faces the feed-side portion of the middle zone, and the other face faces the sidedraw-side portion. The four edges are arranged in two pairs of generally opposing edges. One pair of edges comprises the side edges of the baffle, and each edge of this pair is affixed to the inside column wall of the middle zone. Preferably, each edge of this pair is sealingly engaged to the inside wall in a manner, such as by seal welding, so that with respect to passing between the attached edge and the column wall, fluids in one portion of the middle zone are not in communication with fluids in the other portion. Neither edge of the other pair of generally opposing edges is attached to the column wall. One of the edges of this other pair is the top edge of the dividing wall and delineates the top of the middle zone and the bottom of the top zone. The other edge is the bottom edge of the dividing wall and delineates the bottom of the middle zone and the top of the bottom zone. None of the four edges is necessarily straight. For example, depending on the contour of the column wall, the side edges may be shaped or rounded in order to facilitate attachment of the dividing wall to the column wall. Also, the top edge may be shaped or segmented in a manner that facilitates attachment or fit-up between the dividing wall and plates or other column internals in the top of the middle zone and/or the bottom of the top zone. Likewise, the bottom edge may be shaped to enhance the fit between the dividing wall and plates or internals at the bottom of the middle zone and/or the top of the bottom zone.
The thickness of the dividing wall may be any suitable thickness, subject to mechanical requirements of the structural strength of the dividing wall, attachment to the column wall, or attachment to other column internals. The thickness of the dividing wall depends on the column diameter, but is usually between ⅜ in and ¾ in (9.5 and 19.1 mm) for column diameters between 6 ft and 36 ft (1.8 and 11.0 m). The dividing wall may comprise two walls with a gas space in between, such as disclosed in U.S. Pat. No. 5,785,819. The dividing wall may be constructed from any suitable material, and it is believed preferable that that the dividing wall and the column wall shell are of the same material. The dividing wall material is usually carbon steel. The surfaces of the faces of the dividing wall are generally smooth. However, either surface may have liquid deflectors, such as disclosed in U.S. Pat. No. 5,785,819.
Vapor-liquid contacting devices are installed on the feed-side portion and the sidedraw-side portions in the middle zone of the dividing wall fractionation column. Any suitable vapor-liquid contacting device may be used. Suitable vapor-liquid contacting devices, including plates and packing, and their performances are described at pages 14-24 to 14-61 of Perry's Chemical Engineers' Handbook , 7 th Edition, edited by D. W. Green et al., published by McGraw-Hill, New York, in 1997. As used herein, the term “plate” includes tray, and suitable trays include those formed from a number of adjacent triangular (v-shaped) downcomers or other multiple downcomers, which are disclosed in U.S. Pat. Nos. 5,262,094, 5,366,666, 5,407,605, 5,554,329, and 5,707,563, the teachings of all of which are incorporated herein by reference. A bed-like layer of packing material may be closely adjacent to the bottom surface of the plate in the so-called “disengagement” zone under the plate. The packing may extend to the tray below.
In the feed-side portion, generally from 3 to about 50 or more plates, and more typically from 3 to about 45 plates, are located above the elevation of the feed inlet and below the elevation of the top edge of the dividing wall, with generally from 3 to about 50 or more plates, and more typically from 3 to about 45 plates, located between the feed inlet and the bottom of the dividing wall. In the sidedraw-side portion, generally from 3 to about 50 or more plates, and more typically from 3 to about 45 plates, are located above the sidedraw outlet and below the top edge of the dividing wall, while generally from 3 to about 50 or more plates, and more typically from 3 to about 45 plates, are located between the sidedraw outlet and the bottom of the dividing wall. Plate spacings in part or parts of the feed-side portion may be the same as or different from not only plate spacings in part or parts of the sidedraw-side portion but also spacings in other part or parts of the feed-side portion. Generally, the spacings for the feed plate and the sidedraw plate are generally greater than spacings for other plates. The plates referred to in this paragraph are assumed to have a plate efficiency of 80%. As used herein, plate efficiency is the approach to equilibrium defined as the ratio of the actual change in vapor composition as the vapor passes through the plate to the change that would have occurred if the vapor had reached a state of equilibrium with the liquid leaving the plate. If plates having a plate efficiency other than 80% are used, a person of ordinary skill in the art of fractionation is able to readily determine the appropriate number of plates.
Vapor-liquid contacting devices are also installed in the top and bottom zones of the dividing wall fractionation column, and any of the previously mentioned gas-liquid contacting devices are suitable for either zone. Generally, from 3 to about 50 plates, and more typically from 3 to about 45 plates, are located in the top zone. The bottom zone contains generally from 3 to about 50 plates, and more typically from 3 to about 45 plates. The plates referred to in this paragraph are assumed to have a plate efficiency of 80%. Usually, the spacing between plates is generally uniform in the top zone or in the bottom zone, but is not necessarily the same in both the top and bottom zones.
Persons of ordinary skill in the art of fractionation are aware that, with all Is other variables constant, the number of plates in a fractionation zone generally varies directly with the V/L ratio. As used herein, the V/L ratio, or simply V/L, is the ratio of moles of upflowing vapor (V) to moles of downflowing liquid (L). The designer of a fractionation zone arrives at the optimum number of plates and the optimum V/L ratio by trading-off or balancing the capital cost of the fractionation column on the one hand with the operating cost on the other hand. To achieve a given separation, the higher the V/L, the greater is the number of plates. This relationship applies within the dividing wall fractionation column to each of the top, middle, and bottom zones; within the middle zone to both the feed-side portion and sidedraw-side portions; within the feed-side portion to the plates above the feed inlet and to those below the feed inlet; and within the sidedraw-side portion to the plates above the sidedraw outlet and to plates below the sidedraw outlet. Accordingly, a person of ordinary skill in the art is aware that the number of plates in a zone, portion, or part of a portion of the dividing wall fractionation column may be more than or less than the numbers of plates set forth above, depending on the V/L in that respective zone, portion, or part of a portion of the column. Where packing is used in a zone, either in addition to or instead of plates, such a zone is usually designed based on the hydraulic performance (e.g., pressure drop, flooding, and loading) and mass transfer performance (e.g., height equivalent to a theoretical plate, or HETP).
The plates above the feed inlet in the feed-side portion function as a rectification section to decrease the concentrations of high-boiling hydrocarbons without significantly decreasing the concentrations of low-boiling hydrocarbons in the upflowing vapor. It is believed that a substantial portion of the high-boiling hydrocarbons that are present in the sidedraw stream are high-boiling hydrocarbons that flow upward in the feed-side portion, reach the top of the dividing wall, flow downward through the plates in the sidedraw-side portion, and ultimately exit in the sidedraw stream. Accordingly, the molar ratio V/L in the feed-side portion above the feed inlet, as well as the temperature at the top of the dividing wall in the feed-side portion, are important parameters for controlling the concentration of high-boiling hydrocarbons in the sidedraw stream. In the feed-side portion above the feed inlet, V/L is generally from about 0.1 to about 10.0.
The plates in the top zone function as a further rectification zone not only to further decrease the concentration of the high-boiling hydrocarbons but also to decrease the concentration of heartcut hydrocarbons generally, and of the light key component in particular, in the upflowing vapor in order to attain a highly concentrated overhead stream comprising low-boiling hydrocarbons. V/L in the top zone is generally from about 0.1 to about 10.0.
The plates below the feed inlet in the feed-side portion act as a stripping section to decrease the concentrations of low-boiling hydrocarbons without significantly decreasing the concentrations of high-boiling hydrocarbons in the downflowing liquid. It is believed that a substantial portion of the low-boiling hydrocarbons that are present in the sidedraw stream are low-boiling hydrocarbons that flow downward in the feed-side portion, reach the bottom of the dividing wall, flow upward through the sidedraw-side portion, and ultimately exit in the sidedraw stream. Accordingly, the V/L in the feed-side portion below the feed inlet, as well as the temperature at the bottom of the dividing wall in the feed-side portion, are important parameters for controlling the concentration of low-boiling hydrocarbons in the sidedraw stream. In the feed-side portion below the feed inlet, V/L is generally from about 0.1 to about 10.0.
The plates in the bottom zone act as a stripping zone not only to further decrease the concentration of low-boiling hydrocarbons but also to decrease the concentration of heartcut hydrocarbons in general, and of the heavy key component in particular, in the downflowing liquid in order to attain a highly concentrated bottom stream comprising high-boiling hydrocarbons. In the bottom zone, V/L is generally from about 0.1 to about 10.0.
The plates above the sidedraw outlet in the sidedraw-side portion act as a stripping section to decrease the concentrations of low-boiling hydrocarbons in the descending liquid. Although not a substantial portion of the low-boiling hydrocarbons that are charged to the column with the feed are present in the sidedraw stream, low-boiling hydrocarbons that flow downward in the sidedraw-side portion above the sidedraw outlet can ultimately exit in the sidedraw stream. The V/L above the sidedraw outlet in the sidedraw-side portion is generally from about 0.1 to about 10.0.
The plates below the sidedraw outlet in the sidedraw-side portion act as a rectification section to decrease the concentrations of high-boiling hydrocarbons in the ascending vapor. Although not a substantial portion of the high-boiling hydrocarbons that enter the column in the feed are present in the sidedraw stream, high-boiling hydrocarbons that flow upward in sidedraw-side portion below the sidedraw outlet can ultimately exit in the sidedraw stream. The V/L below the sidedraw outlet in the sidedraw-side portion is generally from about 0.1 to about 10.0
The sidedraw stream is highly concentrated in the heartcut hydrocarbons. The concentration in the sidedraw stream of hydrocarbons lighter than the light key component is generally less than 2.5 wt-% and preferably less than 500 wt-ppm. The concentration in the sidedraw stream of hydrocarbons heavier than the heavy key component is generally less than 2.5 wt-% and preferably less than 500 wt-ppm. As used herein, the term “recovery” of a hydrocarbon component is computed by dividing the quantity of that component recovered from the dividing wall fractionation column in the sidedraw stream by the quantity of that component charged to the dividing wall fractionation column in the feed, and multiplying by 100. If the engineering units of quantity in the numerator and the denominator are the same, then recovery is dimensionless and is expressed as a percent. The recovery of the light key component is generally greater than 85% and preferably greater than 90%, and the recovery of the heavy key component is generally greater than 85% and preferably greater than 90%.
At least a portion of the overhead stream from the dividing wall fractionation column passes to an overhead condenser, which may be a partial condenser or a total condenser. The outlet of the overhead condenser passes to an overhead receiver, which separates the condensed material from any uncondensed overhead materials. At least a portion of the condensed overhead material is refluxed to the dividing wall fractionation column, preferably to a point above the top plate in the top zone. The net overhead stream from the dividing wall fractionation column may be comprise uncondensed material, condensed material, or a combination of uncondensed and condensed material from the overhead stream.
The overhead condenser may be a contact condenser. Contact condensers have been used in crude oil fractionation, in atmospheric residuum fractionation, and in the rerun column of a kerosene strip-and-rerun fractionation process. In a contact condenser, the condensing medium directly contacts the stream being condensed usually over a vapor-liquid contacting device, such as packing or any of the previously mentioned gas-liquid contacting devices. Although the contact condenser may be external to the column, preferably the contact condenser is located within the column, and usually above the uppermost plate of the top zone. Vapors rising from the uppermost plate of the top zone pass upwardly through the contact condenser and countercurrently to the downward flow of the cooling medium. A net stream of uncondensed vapor is withdrawn from the top of the contact condenser and sent to recovery facilities. A liquid stream comprising condensing medium and condensed vapors is withdrawn from the bottom of the contact condenser. A portion of the liquid stream is withdrawn as a net stream from the bottom of the contact condenser and sent to recovery facilities, and the remaining portion is cooled and recycled to the top of the contact condenser. The contacting medium can comprise the low-boiling hydrocarbons or a portion of the overhead liquid of the fractionation column that is recycled to the fractionation column. The use of a contact condenser is advantageous because the pressure drop for the stream being condensed across a contact condenser is small relative to that across other condensers, which in turn allows the dividing wall fractionation column to operate at a lower pressure.
At least a portion of the bottom stream from the dividing wall fractionation column passes to a reboiler. The reboiler may be an external reboiler or an internal reboiler. A pump may be used to pass the portion of the bottom stream through the reboiler. Alternatively, the reboiler may be a so-called thermal siphon reboiler, in which reboiling changes the density of the material being reboiled and that density change, in turn, induces flow through the reboiler. The outlet stream of the reboiler is generally a two-phase mixture of vaporized material from the bottom stream and unvaporized material. At least a portion of the outlet stream of the reboiler passes to the dividing wall fractionation column, preferably to a point below the bottom plate in the bottom zone. The net bottom stream from the dividing wall fractionation column is generally withdrawn as a portion of the bottom stream prior to passing to the reboiler.
The dividing wall fractionation column may also have one or more reboilers, where each reboiler is located at an elevation above that of at least one of the plates in the bottom zone. Such a reboiler, if any, is generally in addition to, rather than instead of, the reboiler to which the bottom stream from the dividing wall fractionation column passes. Although such a reboiler, if any, may be located at an elevation above the bottom of the dividing wall, it is generally located below the bottom of the dividing wall. When such a reboiler is below the bottom of the dividing wall, the reboiler is thus in the bottom zone, rather than in the feed-side portion or in the sidedraw-side portion. However, when located in the bottom zone, such an additional reboiler is located in an orientation relative to the dividing wall fractionation column so that a substantial portion of the outlet stream from that reboiler passes to only one portion of the dividing wall distillation column. By “a substantial portion of the reboiler outlet stream,” it is meant at least 80% and preferably at least 90% of the reboiler outlet stream. Thus, each such reboiler delivers a substantial portion of its outlet stream either to the feed-side portion or to the sidedraw-side portion. In this manner, each such reboiler can deliver a desired amount of reboiled vapor to either portion of the dividing wall fractionation column. Although any such additional reboiler may be an external reboiler, preferably it is an internal reboiler, such as a stab-in reboiler.
The operating pressure of the dividing wall fractionation column may be any suitable pressure at which the relative volatilities of the hydrocarbons to be separated are sufficiently different that the desired separation can be effected by fractionation. The operating pressure is generally from about 7 to about 20 psi(a) (48.3 to 138 kPa(a)). It is believed that, within this operating pressure range, the lower the operating pressure, the lower will be the capital and operating costs of the dividing wall fractionation column.
When using two fully thermally coupled fractionation columns, the feed passes to a prefractionator and the heartcut fraction is recovered in a sidedraw stream from a main column.
As used herein, two fractionation columns are said to be thermally coupled if at least part of the heat transfer that is used for separation in the first column is provided by directly contacting the material being fractionated in the first column with a product stream from the second column. Direct contacting occurs when fluids withdrawn from a location inside the second column (e.g., from a plate, downcomer, packing, liquid sump, vapor space, etc.) are introduced into a location where fluids are present in the first column (e.g., into a plate, downcomer, packing, liquid sump, or vapor space), without first passing through a heat exchanger, such as a condenser or a reboiler. The phrase “without first passing through a heat exchanger” means that the heat content of the fluids entering the first column is generally from 95% to 105%, preferably from 99% to 101%, and more preferably from 99.5 to 100.5%, of the heat content of the fluids withdrawn from the second column. In practice, passing fluid from the second column to the first column results in the transfer of a small amount of heat between the fluid and the ambient surroundings, even if the fluid does not pass through a heat exchanger and even if the fluids are passed through a well-insulated conduit or line. The amount of heat exchanged between the fluid and the ambient surroundings is generally less than 5%, preferably less than 1%, and more preferably less than 0.5%, of the heat content of the fluids.
In a common arrangement of two thermally coupled fractionation columns, instead of each column functioning as a “stand-alone” column with its own reboiler, a vapor stream from a plate (or a downcomer, packing, vapor space, etc.) inside the first column passes through a conduit to the bottom of the second column, and the liquid stream from the bottom of the second column passes through a conduit to a plate (or a downcomer, packing, sump, vapor space, etc.) inside the first column. Thus, the reboiler of the first column provides the reboiling duty for not only the first column but also the second column, and the second column does not have its own reboiler. In another common arrangement, a liquid stream from a plate (or a downcomer, packing, sump, etc.) inside the first column passes through a conduit to the top of the second column, and the vapor stream from the top of the second column passes through a conduit to a plate (or downcomer, packing, sump, vapor space, etc.) inside the first column. In this arrangement, the condenser of the first column provides the condensing duty for the first as well as the second column, and the second column does not have its “own” condenser. Examples of such thermally coupled distillation columns are shown in FIGS. 2 ( a ) and 2 ( b ) of the above-mentioned article by C. Triantafyllou and R. Smith, in Trans IChemE, Vol. 70, Part A, March 1992, 118-132.
FIG. 2 ( c ) of the article by C. Triantafyllou and R. Smith shows an arrangement of two thermally coupled distillation columns that are said to be fully thermally coupled, since one of the columns (the prefractionator) has neither its own condenser nor its own reboiler and the other column (the main column) has both a condenser and a reboiler. The condenser and reboiler of the main column provide the condensing duty and reboiling duty, respectively, not only for the main column but also for the prefractionator. Thus, the vapor stream from the top of the prefractionator passes through a conduit to a plate inside the main column, and a liquid stream from a plate inside the main column passes through a conduit to the top of the prefractionator. Also, the liquid stream from the bottom of the prefractionator passes through a conduit to a plate inside the main column, and a vapor stream from a plate inside the main column passes through a conduit to the bottom of the prefractionator. See also the article by H. Rudd in The Chemical Engineer, Distillation Supplement, Aug. 27, 1992, s14-s15.
When using two fully thermally coupled fractionation columns, the prefractionator separates the feed into a prefractionator overhead vapor stream and a prefractionator bottom liquid stream. In the prefractionator above the feed inlet, the plates act as a rectification section to decrease the concentrations of high-boiling hydrocarbons in the upflowing vapor. There are generally from 3 to about 50 or more plates, and more typically from 3 to about 45 plates, above the elevation of the feed inlet, and the V/L ratio is generally from about 0.1 to about 10. In the prefractionator, below the elevation of the feed inlet, the plates act as a stripping section to decrease the concentrations of low-boiling hydrocarbons without significantly decreasing the concentrations of high-boiling hydrocarbons in the downflowing liquid. There are generally from 3 to about 50 or more plates, and more typically from 3 to about 45 plates, and V/L is generally from about 0.1 to about 10 below the elevation of the feed inlet to the prefractionator. The plates referred to in this paragraph are assumed to have a plate efficiency of 80%. The vapor-liquid contacting devices previously described for use in the dividing wall fractionation column are suitable for use in the prefractionator.
In the main column, the plates above the elevation where the prefractionator overhead vapor stream is introduced and the liquid stream from the main column is withdrawn for the prefractionator help to decrease the concentration of high-boiling hydrocarbons and to decrease the concentration of heartcut hydrocarbons in the upflowing vapors. In this part of the main column, there are generally from 3 to about 50 or more plates, and more typically from 3 to about 45 plates, and V/L is generally from about 0.1 to about 10.0. Below the elevation where the prefractionator overhead vapor is introduced and the liquid stream from the main column is withdrawn for the prefractionator and above the elevation where the sidedraw stream is withdrawn, the plates act as a stripping section to decrease the concentrations of low-boiling hydrocarbons from the descending liquid. There are generally from 3 to about 50 or more plates, and typically from 3 to about 45 plates, in this area of the main column, and V/L is generally from about 0.1 to about 10.0. The area of the main column below the elevation where the sidedraw stream is withdraw and above the elevation where the vapor stream from the main column is withdrawn and the prefractionator bottom liquid stream is introduced acts as a rectification section to decrease the concentrations of high-boiling hydrocarbons in the ascending vapors. This area of the main column generally contains from 3 to about 50 or more plates, and usually from 3 to about 45 plates, and V/L is generally from about 0.1 to about 10.0. In the main column below the elevation where the vapor stream from the main column is withdrawn and the prefractionator bottom liquid stream is introduced, there are generally from 3 to about 50 or more plates, and typically from 3 to about 45 plates. This area of the main column acts as a stripping zone to decrease the concentrations of low-boiling hydrocarbons and of heartcut hydrocarbons, including the heavy key component, and V/L is generally from about 0.1 to about 10.0. The plates referred to in this paragraph are assumed to have a plate efficiency of 80%. Any suitable plate spacing(s) may be used in the main column. The vapor-liquid contacting devices previously described for use in the dividing wall fractionation column are suitable for use in the main column. In a manner similar to that described previously for the dividing wall fractionation column, a person of ordinary skill in the art of fractionation can determine optimum numbers of plates and optimum V/L ratios for the main column, as well for in the prefractionator column.
When using two fully thermally coupled fractionation columns, the composition of the sidedraw stream withdrawn from main column is generally the same as that already described for the sidedraw stream withdrawn from the dividing wall fractionation column. In addition to producing a sidedraw stream, the main column also produces a net overhead stream and a net bottom stream. The composition of the main column's net overhead stream is generally the same as that described previously for the net overhead stream of the dividing wall fractionation column, and the composition of the main column's net bottom stream is generally the same as that described previously for the net bottom stream of the dividing wall fractionation column.
Regardless whether the sidedraw stream is produced by a dividing wall fractionation column or by two fully thermally coupled fractionation columns, the sidedraw stream passes to a zone for the manufacture of alkylbenzenes, which is referred to herein as the alkylbenzene zone. The alkylbenzene zone generally comprises a series of subzones, which together produce the desired alkylbenzene product. Such a series of subzones for the production of LAB is well known to persons of ordinary skill in the art of hydrocarbon processing and need not be described in detail herein. A suitable series of subzones is described in the paper entitled LAB Production , by R. C. Schulz, P. R. Pujado, and B. V. Vora, presented at the 2 nd nd World Conference on Detergents, held at Montreux, Switzerland, during Oct. 5-10, 1986. The teachings of the Schulz et al. paper are hereby incorporated herein by reference.
First, the sidedraw stream generally passes to a hydrotreating subzone in order to remove sulfur and nitrogen contaminants that would otherwise affect the quality of the LAB product or the performance of downstream subzones, which are described hereinafter. The hydrotreating subzone is optional, since it may be omitted if the levels of contaminants in the sidedraw stream are sufficiently low. General practice for LAB production, however, includes the hydrotreating subzone. The particular arrangement of the hydrotreating subzone, such as the hydrotreating reaction conditions, the use of any hydrotreating catalyst, and the routing of process streams within the hydrotreating subzone, is not critical to the success of the subject invention. Further information on suitable hydrotreating subzones may be found in Chapter 8.3 entitled “UOP Unionfining Technology” of the previously mentioned book edited by Meyers. The teachings of Chapter 8.3 are hereby incorporated herein by reference.
The hydrotreated heartcut produced by the hydrotreating subzone passes to a paraffin separation subzone that separates the linear paraffins (normal paraffins) from other hydrocarbons, such as naphthenes, aromatics, and branched paraffins. Branched paraffins are rejected to the extent needed to achieve the desired linearity of the LAB product. Persons of ordinary skill in the art of hydrocarbon processing know of several suitable paraffin separation subzones. The particular arrangement of the paraffin separation subzone, including its flow scheme, any adsorbent, its equipment, and its operating conditions, are not critical to the success of the subject invention. Further information on suitable paraffin separation subzones may be found in Chapter 10.3, entitled “UOP Sorbex Family of Technologies,” and Chapter 10.7, entitled “UOP Molex Process for Production of Normal Paraffins,” of the previously mentioned book edited by Meyers. The teachings of Chapter 10.3 and 10.7 are hereby incorporated herein by reference.
The paraffin separation subzone product stream comprising normal paraffins passes to a paraffin dehydrogenation subzone that converts paraffins to olefins, and in particular linear paraffins to linear monoolefins. The particulars of the arrangement of the paraffin dehydrogenation subzone, such as the use of any dehydrogenation catalyst, the dehydrogenation reaction conditions, and how process streams flow within the paraffin dehydrogenation subzone, are not critical to the success of the subject invention. The product of the paraffin dehydrogenation subzone comprises a mixture of olefins and unreacted paraffins, since not all of the paraffins convert to olefins in the dehydrogenation subzone. Further information on suitable paraffin dehydrogenation subzones may be found in Chapter 5.2 of the previously mentioned book edited by Meyers.
The olefins, preferably linear monoolefins, produced by the paraffin dehydrogenation subzone pass as in a mixed paraffin-olefin stream to an alkylation subzone, where the olefins alkylate an aromatic compound in the presence of an alkylation catalyst in an alkylation reactor. Although the aromatic compound reactant may be an alkylated derivative of benzene, the preferred aromatic compound reactant for the production of LAB is benzene. While the alkylation catalyst may be a liquid catalyst, such as hydrofluoric acid or sulfuric acid, it is preferably a solid catalyst. Preferred fluorided silica-alumina solid catalysts are disclosed in U.S. Pat. Nos. 5,196,574 and 5,344,997. Additional details on suitable alkylation subzones using solid or liquid catalysts are described in Chapter 1.5 of the previously mentioned book edited by Meyers. The hydrocarbonaceous effluent recovered from the alkylation reactor passes to a product recovery section of the alkylation subzone, which generally comprises at least three columns. The first column, or benzene column, separates the reactor effluent and removes unreacted aromatic compound reactant (e.g., benzene) as an overhead stream for recycle to the alkylation reactor. The second, or paraffin, column removes paraffins from a bottom stream of the benzene column and produces a paraffin-containing overhead stream for recycle to the paraffin dehydrogenation subzone. The third, or LAB, column separates a bottom stream from the paraffin column and produces an overhead stream containing LAB, which is recovered as product. Heavy alkylate is recovered as a bottom stream from the LAB column and may be further separated in a fourth column to recover any LAB present in the LAB column bottom stream.
In additional embodiments of the subject invention, this invention efficiently uses the heat that is removed by the overhead condenser of either the second column (paraffin column) or third column (LAB column) in the product recovery section of the alkylation subzone. The overhead condenser of each column condenses at least a portion of the column's overhead stream in order to produce sufficient liquid for reflux and usually for a net liquid overhead stream. In so doing, the overhead condenser removes a significant amount of heat from each column's overhead stream. It has now been recognized that at least a portion of this heat can be used to provide reboiler duty in the dividing wall fractionation column, rather than rejecting this heat to the atmosphere or to a heat sink, which is not energy efficient. Accordingly, in one embodiment, at least a portion of the overhead stream of the paraffin column is used as the heating medium for a reboiler that delivers vapor to either the feed-side portion or the sidedraw-side portion of the dividing wall fractionation column. In another embodiment, at least a portion of the overhead stream of the LAB column is used as the heating medium for a reboiler that delivers vapor to either the feed-side portion or the sidedraw-side portion of the dividing wall fractionation column.
The reboiler to which some or all of either overhead stream is routed may be the bottom reboiler of the dividing wall fractionation column, one or more of the previously-described additional reboilers of the dividing wall fractionation column, or both. The optimum reboiler for a given overhead stream to exchange heat depends mainly on the difference between the temperature of the overhead stream and the temperature of the fluid being reboiled in the dividing wall fractionation column. For a given surface area for transferring heat, the greater the temperature difference, the more rapidly heat will transfer from the overhead stream to the fluid being reboiled in the dividing wall fractionation column. Alternatively, for a given rate of heat transfer to the fluid being reboiled, the greater the temperature difference, the less is the surface area required for transferring heat. Accordingly, the higher the temperature of the fluid in the dividing wall fractionation column that is being heated by a reboiler, the higher is the temperature of the overhead stream which is passed as the heating medium to that reboiler. The temperature of the overhead stream (heating medium) is greater than the temperature of the fluid being reboiled generally by more than 15° F. (7° C.), and preferably by more than 20° F. (11° C.).
In addition to temperature, another factor influencing the choice of which overhead stream is routed to which reboiler is the flow rate of the overhead stream. For a given overhead stream temperature, the greater the flow rate of the overhead stream, the greater is the amount of heat that can be transferred from the overhead stream. Thus, for a given difference between the temperature of the overhead stream and that of the stream being reboiled, then the greater the desired amount of heat to be transferred, the more preferable it is to use as a heating medium the overhead stream having a greater flow rate.
FIGS. 1 and 2 each illustrate a preferred embodiment of the subject invention. FIGS. 1 and 2 are presented solely for purposes of illustration and are not intended to limit the scope of the invention as set forth in the claims. FIGS. 1 and 2 show only the equipment and lines necessary for an understanding of the invention and does not show equipment such as pumps, compressors, heat exchangers, and valves which are not necessary for an understanding of the invention and which are well known to persons of ordinary skill in the art of hydrocarbon processing.
Referring now to FIG. 1, a kerosene boiling range fraction comprising C 9 to C 15 hydrocarbons enters via a line 12 into a dividing wall fractionation column 10 . The dividing wall column 10 contains a dividing wall 16 and plates, one of which is designated in FIG. 1 by the item 14 . An overhead stream comprising C 9 and C 10 hydrocarbons is recovered from the top of the dividing wall column 10 and passes via line 18 to condenser 20 . Using a suitable cooling medium, condenser 20 condenses a portion of the overhead steam and produces a two-phase condenser outlet stream comprising hydrocarbonaceous vapors and liquids. Condenser outlet stream in line 22 enters overhead receiver 24 where the hydrocarbons phase separate into uncondensed vapors which leave receiver 24 via line 26 and condensed liquids which exit receiver 24 via line 27 . A portion of the condensed liquids in line 27 refluxes to column 10 via line 28 with the remainder exiting the process via line 29 .
A bottom stream comprising C 14 and C 15 hydrocarbons is withdrawn from the bottom of column 10 via line 30 . A portion of the hydrocarbons in line 30 passes through line 34 , is partially vaporized in reboiler 36 using any suitable heating medium, and returns to column 10 as a two-phase reboiler outlet stream via line 38 . The remainder of the hydrocarbons in line 30 are rejected from the process via line 32 . In addition to external reboiler 36 , column 10 is reboiled by two other internal stab-in reboilers, 65 and 74 . Stab-in reboiler 74 delivers reboiled vapors to the feed-side portion of dividing wall column 10 , while stab-in reboiler 65 provides reboiled vapors to the sidedraw-side portion of column 10 . A sidedraw stream comprising C 11 to C 13 hydrocarbons is withdrawn from column 10 through line 40 and passes to alkylbenzene zone 80 .
Alkylbenzene zone 80 consists of hydrotreating subzone 42 , paraffin separation subzone 46 , paraffin dehydrogenation subzone 50 and alkylation subzone 90 . In hydrotreating subzone 42 , a hydrogen-containing stream entering via line 41 reacts with sulfur and nitrogen contaminants in the sidedraw stream in order to produce a hydrotreated heartcut stream having decreased levels of sulfur and nitrogen contaminants in line 44 . The hydrotreated heartcut stream enters paraffin separation subzone 46 , which produces a raffinate stream comprising naphthenes, aromatics, and branched paraffins which is rejected from the process via line 45 . An extract stream comprising linear (normal) paraffins is recovered from the paraffin separation subzone 46 via line 48 . The extract stream and a cooled recycle paraffin stream in 67 enter paraffin dehydrogenation subzone 50 , which dehydrogenates linear paraffins to linear monoolefins to produce an olefin-containing stream as a primary product flowing through line 52 and a hydrogen-containing stream as a by-product flowing through line 51 . Although not shown in FIG. 1, a portion of the hydrogen-containing stream in line 51 may be used to form at least a portion of the hydrogen-containing stream in line 41 .
The olefin-containing stream in line 52 and benzene feedstock in line 55 enter alkylation subzone 90 , which consists of alkylation reactor 54 , benzene column 58 , paraffin column 62 , and LAB column 68 . The benzene feedstock flowing in line 55 combines with a recycle benzene stream 53 , in a combined stream of feed and recycle benzene enters alkylation reactor 54 through line 57 . In alkylation reactor 54 , linear olefins from the olefin-containing stream alkylate benzene from the combined stream to produce linear alkylbenzenes (LAB) which is withdrawn from alkylation reactor 54 via an alkylation reactor effluent stream flowing in line 56 . In addition to containing the LAB product, the alkylation reactor effluent stream contains unreacted benzene, paraffins, and heavy alkylbenzene by-products. In benzene column 58 , the alkylation reactor effluent stream is separated into a recycle benzene stream comprising benzene which is recovered from the overhead of the benzene column 58 and a benzene column bottom stream depleted in benzene which is recovered from the bottom of benzene column 58 in line 60 . The benzene column bottom stream enters paraffin column 62 which separates out paraffins and produces a recycle paraffin stream flowing in line 64 and paraffin column bottom stream which is paraffin-depleted and flows through line 66 . The paraffin column bottom stream enters LAB column 68 , where the product LAB is recovered in an LAB column overhead stream flowing in line 70 . The product LAB comprises alkylbenzenes having an alkyl group having from 11 to 13 carbon atoms. Heavy alkylaromatics, which are defined as alkylaromatics that are heavier than the desired product LAB, comprise alkylbenzenes having an alkyl group having 14 or more carbon atoms. Heavy alkylaromatics are recovered in an LAB column bottom stream which is rejected from the process via line 72 .
The recycle paraffin stream in line 64 is the heating medium for internal reboiler 65 in column 10 . Recycle paraffin stream 64 may enter reboiler 65 as a vapor-phase stream, a liquid-phase stream, or a mixed-phase vapor-liquid stream. Within reboiler 65 , the recycle paraffin stream may or may not undergo a phase change as heat is transferred from the recycle paraffin stream to the fluids in column 10 . After having transferred heat through reboiler 65 , the now-cooled recycle paraffin stream passes to paraffin dehydrogenation subzone 50 as previously described. The LAB column overhead stream in line 70 is the heating medium for internal reboiler 74 in column 10 . On entering reboiler 74 , the LAB column overhead stream may be vapor phase, liquid phase, or a mixture of vapor and liquid phases. While transferring heat through reboiler 74 to fluids in column 10 , the LAB column overhead stream may or may not undergo a change in phase, such as at least partial condensation from vapor phase to liquid phase. After having transferred heat via reboiler 74 , LAB is recovered from the process in an LAB product stream in line 76 .
FIG. 2 shows another embodiment of the subject invention wherein the kerosene boiling range fraction feedstock is separated in two fully thermally coupled fractionation columns 110 and 120 rather than in a single dividing wall fractionation column 10 as in FIG. 1 . For the sake of brevity, items in FIG. 2 that correspond to items that have already been shown and described in FIG. 1 are not shown in or described in FIG. 2 . Items in FIG. 2 that correspond to items in FIG. 1 have the same reference number, such as items numbers 26 , 29 , 32 , 40 , 64 , 67 , 70 and 76 .
Referring now to FIG. 2, a kerosene boiling range fraction feedstock enters the process via line 112 and flows into preheat exchanger 114 . In exchanger 114 , the feedstock is heated by indirect heat exchange with the LAB column overhead stream flowing in line 70 . The heated feedstock flows through line 116 and enters prefractionator 110 . Prefractionator 110 contains plates, one of which is denoted with item 123 . A prefractionator overhead stream is recovered from the top of prefractionator 110 via line 122 and passes to main column 120 . A main column liquid draw stream flows from main column 120 to prefractionator 110 via line 118 . A prefractionator bottom stream is recovered from the bottom of prefractionator 110 and flow through line 124 to main column 120 . A main column vapor draw stream flows from main column 120 to the bottom of prefractionator 110 through line 126 . A main column overhead stream comprising C 9 and C 10 hydrocarbons is recovered from the top of main column 120 and passes via line 128 to condenser 130 . Condenser 130 uses a suitable cooling medium and condenses a portion of the main column overhead steam and produces a two-phase condenser outlet stream comprising hydrocarbonaceous vapors and liquids. The condenser outlet stream in line 132 enters overhead receiver 134 where the hydrocarbons phase separate into uncondensed vapors which leave receiver 134 via line 26 and condensed liquids which exit receiver 134 via line 136 . A portion of the condensed liquids in line 136 refluxes to main column 120 via line 138 with the remainder exiting the process via line 29 .
A main column bottom stream comprising C 14 and C 15 hydrocarbons is withdrawn from the bottom of main column 120 via line 150 . A portion of the hydrocarbons in line 150 passes through line 148 , is partially vaporized in reboiler 146 using any suitable heating medium, and returns to main column 120 as a two-phase reboiler outlet stream via line 144 . The remainder of the hydrocarbons in line 150 are rejected from the process via line 32 . In addition to external reboiler 146 , main column 120 is reboiled by internal stab-in reboiler 142 . The heating medium for stab-in reboiler 142 is the paraffin recycle stream in line 64 , which after being cooled in reboiler 142 , flows through line 67 to paraffin dehydrogenation subzone 50 . Stab-in reboiler 142 produces reboiled vapors at an elevation in main column 120 above the elevation of the introduction of the prefractionator bottom stream via line 124 and below the elevation of the withdrawal of the sidedraw stream via line 40 . The sidedraw stream comprises C 11 to C 13 hydrocarbons and passes to alkylbenzene zone 80 .
EXAMPLES
The following examples illustrate embodiments of the invention for the separation of a kerosene boiling range fraction comprising C 9 to C 15 hydrocarbons into a light stream comprising low-boiling hydrocarbons comprising C 9 and C 10 hydrocarbons, a sidedraw stream comprising heartcut hydrocarbons comprising C 11 , C 12 , and C 13 hydrocarbons, and a heavy stream comprising high-boiling hydrocarbons comprising C 14 and C 15 hydrocarbons. The light key component is normal C 11 paraffin and the heavy key component is normal C 13 paraffin. In the sidedraw stream in all of the following examples, the concentration of components lighter than normal C 11 paraffin is less than 2.5 wt-%, and the concentration of components heavier than normal C 13 paraffin is less than 2.5 wt-%. More than 85 mol-% of the normal C 11 , paraffin, and more than 85 mol-% of the normal C 13 paraffin, in the feed stream are recovered in the sidedraw stream. These examples are based on engineering calculations and scientific fractionation predictions, and are not intended to limit the invention as set forth in the claims.
These examples make reference to FIG. 3, which shows a dividing wall fractionation column 10 and which uses the same reference numbers as FIG. 1 to avoid unnecessary repetition. The trays in column 10 in this Example 3 have a plate efficiency of 80%. Tray numbers in FIG. 3 are preceded by a “#” symbol to distinguish them from reference numbers. Two tray numbering systems are used in FIG. 3 . One system assigns numbers to trays in the feed-side portion of the middle zone in ascending order from the top to the bottom of the feed-side portion. In this numbering system, the tray at the top of dividing wall 16 is denoted tray # 1 , fifteen trays (not shown in FIG. 3) are between tray # 1 and feed tray # 17 , and eight trays (not shown) are between the feed tray and tray # 26 , which is in the feed-side portion of the middle zone at the bottom of dividing wall 16 . The other numbering system numbers trays in the top zone, the sidedraw-side portion of the middle zone, and the bottom zone in ascending order from the top to the bottom of dividing wall fractionation column 10 . In this second system, the tray that is uppermost in dividing wall fractionation column 10 and which is shown just below line 28 is denoted as tray # 1 . Further down column 10 and on the sidedraw-side portion of the middle zone, the tray shown at the top of dividing wall 16 is tray # 36 , the side-draw tray is tray # 40 , and the tray at the bottom of dividing wall 16 is tray # 52 . Below the middle zone, this second numbering system continues to tray # 69 , which is shown just above line 38 and is the lowermost tray in dividing wall fractionation column 10 . Thus, thirty-four trays (not shown in FIG. 3) are in the top zone between tray # 1 and tray # 36 . Three trays (not shown) are in the sidedraw-side portion between tray # 36 and the side-draw tray # 40 . Eleven trays (not shown) are in the sidedraw-side portion between the side-draw tray and tray # 52 . Finally, sixteen trays (not shown) are in the bottom zone between tray # 52 and tray # 69 .
Example 1
Referring now to FIG. 3, a kerosene boiling range fraction comprising C 9 to C 15 hydrocarbons is charged to dividing wall fractionation column 10 . The feed temperature is 421° F. (216° C.). In the feed-side portion of the middle zone, V/L is 4.5 between trays # 1 and # 17 , V/L is 0 . 6 between trays # 17 and # 26 , the temperature at tray # 1 is 426° F. (219° C.), and the temperature at tray # 26 is 489° F. (254° C.). In the top zone, V/L is 1.2 between uppermost tray # 1 and the two trays at the top of divided wall 16 , which are tray # 1 (feed-side portion) and tray # 36 (sidedraw-side portion). In the sidedraw-side portion of the middle zone, V/L is 0.8 between trays # 36 and # 40 , V/L is 1.5 between trays # 40 and # 52 , the temperature at tray # 36 is 470° F. (243° C.), and the temperature at tray # 52 is 520° F. (271° C.). In the bottom zone, V/L is 0.8 between tray # 69 and the two trays at the bottom of divided wall 16 , which are tray # 26 (feed-side portion) and tray # 52 (sidedraw-side portion).
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A process for the production of alkylaromatic hydrocarbons by alkylating aromatic hydrocarbons with linear olefinic hydrocarbons is disclosed. The linear olefinic hydrocarbons are produced by dehydrogenating linear paraffinic hydrocarbons which are extracted from a heartcut that is distilled from a kerosene boiling range fraction in either a dividing wall fractionation column or in two fully thermally coupled fractionation columns. The process significantly decreases the cost of utilities in producing alkylaromatic precursors for detergent manufacture.
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PRIORITY CLAIM
[0001] The present application is a continuation of U.S. patent application Ser. No. 12/752,865, filed Apr. 1, 2010, which claims priority to French Patent Application FR 0952203 filed Apr. 3, 2009 which is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally relates to the field of decoy systems, notably for mines or explosive devices, laid, buried or more generally arranged at the roadside. More specifically, the invention relates to the decoying of improvised explosive devices which usually contain destructive, flammable and/or deadly chemical products that are commonly called IED (improvised explosive devices). The invention also relates, generally, to the decoy systems or decoys that make it possible to provoke the triggering of explosive devices or mines buried or placed at the roadside.
[0004] 2. Description of the Relevant Art
[0005] Conventionally, decoy systems or decoys are used to provoke the explosion of mines or explosive devices at a distance from the mine-clearing vehicles.
[0006] To this end, the decoy systems can comprise means for emitting radiation in the infrared spectrum so as to be detected by these devices or mines that include infrared sensors.
[0007] To allow for the emission of such radiation, one solution consists in fitting, between two metallic plates, an electrical resistance powered by an energy source.
[0008] In order to ensure an emission of infrared radiation that is likely to provoke the triggering of both mines and improvised explosive devices, it is, however, necessary for the electrical energy power source to be able to have a relatively high power, of the order of several kilowatts.
[0009] This is incompatible with an embedded system on-board a vehicle or pushed by a mine-clearing vehicle that also has to be used for several hours. Moreover, with this solution, the temperature rise time of the system is relatively great.
[0010] In order to provide the infrared radiation emission means with an input of electrical energy that is sufficient to allow for the triggering of mines and improvised explosive devices, it is possible to use a generator set. However, this solution has the major drawbacks of being relatively bulky and very heavy.
[0011] Also known, from the European Patent 1 054 230, is a decoy system linked to the front of a tank and mainly comprising vertical panels on which are provided metal conductors powered by the electric batteries of the tank to control their temperature.
[0012] The purpose of this system is to reproduce emissivity in the infrared range close to that of a tank to allow for the triggering of roadside mines. In this respect, one area of the panels can be slaved to a temperature of between 15 and 20° C. above ambient temperature, whereas a neighboring area of the panels can be slaved to a lower temperature, for example between 5 and 10° C. above ambient temperature.
[0013] Given the heat dissipation, the electrical energy supplied to the panels by the batteries can prove insufficient to allow for the triggering of roadside mines as soon as the tank is moving at relatively high speeds, of the order of 50 kilometers per hour.
[0014] Moreover, the electrical energy likely to be delivered by the batteries of the tank does not make it possible to obtain a sufficient temperature on the panels to allow for the triggering of improvised explosive devices. In practice, such devices usually explode when they detect a temperature higher than those recommended in EP 1 054 230.
SUMMARY OF THE INVENTION
[0015] The aim of the present embodiments is to remedy the drawbacks of the prior art systems.
[0016] More particularly, the embodiments herein provide a decoy system, notably for terrestrial improvised explosive devices, that is autonomous, cost-effective and compact.
[0017] Another aim of the embodiments is to provide a decoy system for which the temperature rise time, when it is started up, is relatively short.
[0018] A further aim of the embodiments is to provide a system that makes it possible to trigger both mines arranged at the roadside and also improvised explosive devices.
[0019] In one embodiment, the decoy system, notably for mines or terrestrial improvised explosive devices, is provided with a means of producing heat energy including an air or water boiler and a means of emitting radiation in the infrared spectrum including a chamber fed with fluid by the heat energy production means. The chamber is provided with internal fins able to promote a build-up of heat energy inside the latter. The system also includes at least one detection means for determining the temperature of the chamber or the temperature of the fluid between the production means and the emission means, and a control unit able to control the operation of the means of producing heat energy at least according to the determined temperature.
[0020] In one embodiment, the system also includes an outside temperature sensor. The control unit is able to drive the production means so that the difference between the detected temperatures is greater than a predetermined threshold value and able to check that said difference is at least equal to said threshold value.
[0021] Advantageously, the internal fins extend perpendicularly to the inlet stream into the chamber of the fluid emitted by the heat energy production means. The internal fins can be arranged in the form of successive rows, parallel or not, the fins of one row being separated so as to delimit a space located at least partly facing an orifice feeding the chamber with fluid. Advantageously, the dimension of the space provided between the internal fins of a row decreases progressively from one row of fins to another. The space between the fins is greatest for the row located in the vicinity of the feed orifice.
[0022] In one embodiment, the chamber includes substantially smooth outer walls.
[0023] Advantageously, the boiler includes an exhaust duct for gases passing through the chamber.
[0024] The chamber can include at least one fluid outlet orifice and, possibly, an associated closing valve. The position of the closing valve can be modified manually or mechanically via the control unit.
[0025] In one embodiment, a recirculation duct tapped onto the chamber is provided to reinject, partially or totally inside the boiler, the fluid from the chamber. This duct extends between the chamber and the boiler and is in fluidic communication with them.
[0026] In one embodiment, the means of detecting the temperature of the chamber includes a temperature sensor.
[0027] In one embodiment, the control unit is able to control the operation of the energy production means according to the difference between the measured temperatures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The present invention will be better understood from reading the detailed description of an embodiment taken as a nonlimiting example and illustrated by the appended drawings, in which:
[0029] FIGS. 1 to 3 diagrammatically represent a decoy system, and
[0030] FIG. 4 is a perspective cross-sectional view of an infrared radiation emission means of the system of FIGS. 1 to 3 .
[0031] While the invention may be susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. The drawings may not be to scale. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but to the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] FIG. 1 diagrammatically represents a decoy system 10 mounted on a supporting mast 12 , which is in turn fixed to a towing bar 14 which is attached to the front part of a vehicle 16 . As illustrated in FIG. 2 , the supporting mast 12 can alternatively be fixed directly to the front of the vehicle 16 .
[0033] The decoy system 10 is particularly suitable for making it possible, ahead of the passage of the vehicle 16 , to trip a mine or improvised explosive device laid on a road or buried. The distance separating the system 10 and the front of the vehicle 16 is sufficiently great to avoid destruction of the vehicle 16 when the mine or device explodes.
[0034] As illustrated more visibly in FIG. 3 , the decoy system 10 mainly includes a boiler 20 for the production of heat energy and an infrared radiation emission means 22 supplied with fluid by the boiler. The boiler 20 and the emission means 22 are fixed by any appropriate means to a supporting shielding 24 . The supporting shielding 24 includes clamping plates 26 and screws (not represented) for adjusting the position of and securing the system 10 on the mast 12 ( FIGS. 1 and 2 ). The emission means 22 is in a vertical position so as to be able to be detected by the sensor associated with the mine or explosive device.
[0035] The boiler 20 is used to reheat a fluid, in this case air, and direct it to the means 22 for the purpose of the emission of radiations, in the infrared spectrum, likely to provoke the tripping of a mine or improvised explosive device.
[0036] The boiler 20 is connected to a fuel tank 28 via a duct 30 . The boiler 20 includes a burner, a dosing pump and a ventilation means (not represented). The ventilation means sucks in air from an inlet opening 32 provided at a bottom end of the shielding 24 and expels it toward an exhaust duct 41 , after having mixed it with the fuel pumped from the tank 28 then passed through the burner. The reheated air at the outlet of the boiler 20 is conveyed by a duct 37 to feed the emission means 22 . As an indication, the boiler 20 can have a length of 550 mm, and a width and a thickness of 200 mm. In this embodiment, the boiler is of the air type. Alternatively, it is, however, possible to provide a water boiler to feed the emission means 22 with heat energy.
[0037] There now follows a description, with reference to FIG. 4 , of the infrared radiation emission means 22 . The emission means 22 is represented here in cross section, the part of the emission means 22 not illustrated in the figure being identical to that which will be described.
[0038] The emission means 22 includes a sealed chamber 34 provided internally with fins 36 a , 36 b arranged in the form of parallel successive rows, in this case twelve such rows. The chamber 34 is made of light alloy and here has a generally parallelepipedal shape. Obviously, the chamber 34 could have a different overall shape. Alternatively, it could also be possible to provide non-parallel fins. As an indication, the chamber 34 can have a height of 400 mm, a width of 800 mm and a thickness of 110 mm. The system 10 can have a weight of approximately 30 kg. The chamber 34 includes pairs of opposite edges 34 a , 34 b and 34 c , 34 d . In this figure, the emission means 22 is represented in a position that is assumed to be vertical. The edges 34 a , 34 b therefore respectively constitute top and bottom edges. The chamber 34 is fed with hot air via the duct 37 which extends from the boiler 20 and is fixedly mounted inside a feed orifice 38 provided in the top edge 34 a.
[0039] As indicated previously, the horizontal internal fins 36 a , 36 b are arranged in the form of parallel successive rows. The vertical spacing provided between two immediately adjacent rows of fins is constant.
[0040] The fins 36 a , 36 b extend between the edges 34 c and 34 d , being parallel to the edges 34 a and 34 b . The fins 36 a , 36 b of the first row situated in the vicinity of the duct 37 occupy substantially most of the width of the chamber 34 between the edges 34 c , 34 d . A first fin 36 a of this row extends from the edge 34 c to the vicinity of an area situated in the extension of the duct 37 , i.e. facing the feed orifice 38 . The second fin 36 b extends horizontally in the extension of the first fin 36 a while being laterally offset relative to the latter until it reaches the vicinity of the edge 34 d , while allowing a small space to remain between it and said edge. The fins 36 a , 36 b of the first row are separated from one another so as to delimit a space 40 situated facing the feed orifice 38 . The lateral dimension of the space 40 is substantially equal to the diameter of the feed orifice 38 . The space 40 allows the air inlet flow to be directed to the subsequent rows of fins 36 a , 36 b.
[0041] Downstream of the first row, using the direction of circulation of the air inside the chamber 34 as a reference, the second row includes a fin 36 a extending from the edge 34 c . The fin 36 a of the second row has a length slightly greater than that of the fin 36 a of the first row. The fin 36 b of the second row has a length identical to that of the first row while, however, being offset toward the fin 36 a of the second row so that the space 40 between fins of that row is slightly less than that of the first row. Thus, a greater space is provided between the fin 36 b of the second row and the edge 34 d.
[0042] The arrangement of each of the subsequent rows of fins relative to the immediately preceding row is similar to that of the second row with respect to the first row. Thus, the space 40 between the fins 36 a , 36 b of one and the same row gradually decreases with distance away from the feed orifice 38 so that, for the last row of fins 36 a and 36 b situated in proximity to the bottom edge 34 b , the space between the two fins is almost zero. The space between the fin 36 b of this last row and the edge 34 d is substantially equal to the diameter of an outlet orifice 39 provided in the thickness of the bottom edge 34 b in the vicinity of the edge 34 d . The applicant has determined that the provision of a space 40 between fins that has a general V shape and decreases with distance away from the feed orifice 38 allows for a better distribution of the heat inside the chamber 34 . Thus, a relatively uniform temperature of the chamber 34 is obtained.
[0043] The fins 36 a , 36 b of the different rows are arranged perpendicularly to the direction of flow of the air at the outlet of the duct 37 so as to retain this air flow within the chamber 34 while progressively orienting it toward the outlet orifice 39 . The arrangement of the internal fins 36 a , 36 b in the chamber 34 tends to favor the concentration of heat inside the latter so as to facilitate the emission of an infrared radiation that is substantially greater than the ambient infrared radiation. The appearance of a hot area or spot that can be detected by a mine or improvised explosive device is thus obtained. Obviously, it could be possible to provide a different arrangement of the fins 36 a , 36 b also tending to favor the concentration of heat. Furthermore, so as to limit the heat dissipation by the emission means 22 , the outer walls of the chamber 34 are substantially smooth, i.e. without any fins or other means favoring the evacuation of heat.
[0044] To adjust the hot air flow rate at the outlet from the chamber 34 , the latter includes a valve 42 , the position of which can be modified manually or mechanically, for example as a function of the outside temperature, so as to vary the degree of opening of the outlet orifice 39 . Alternatively, it is possible not to provide such a valve.
[0045] In a variant embodiment, it is also possible to provide a closed circuit mode of operation of the system. To this end, the chamber 34 includes, instead of the outlet orifice 39 or in association with said orifice and its closing valve 42 , a recirculation duct communicating with the inside of the chamber and reinjecting the hot air, or water, obtained from the chamber inside the boiler. Such a closed circuit mode of operation is possible by virtue of the use of an air or water boiler.
[0046] The exhaust duct 41 for the gases from the boiler 20 snakes up and down inside the chamber 34 . The exhaust duct 41 extends through the top edge 34 a in the vicinity of the duct 37 and discharges through the bottom edge 34 b in proximity to the outlet orifice 39 . The exhaust duct 41 participates in the raising of the temperature of the chamber 34 when the system 10 is started up, thus helping to reduce the time needed for the emission of the desired infrared radiation.
[0047] Referring once again to FIG. 3 , the decoy system 10 also includes a control unit 46 fixed to the shielding 24 and controlling the operation of the boiler 20 as a function of the infrared radiation to be emitted.
[0048] To this end, the system 10 includes a temperature sensor 48 mounted in the duct 37 and able to measure the temperature of the hot air at the outlet of the boiler 20 which is conveyed to the chamber 34 . The system 10 also includes a temperature sensor 50 mounted on the shielding 24 between the inlet opening 32 and the inlet of the boiler 20 so as to measure the temperature of the outside air that is directed toward said boiler. The temperature sensors 48 , 50 are connected to the control unit 46 via connections 52 , 54 that are diagrammatically illustrated as dotted lines.
[0049] The control unit 46 includes, stored in memory, all the hardware and software means that make it possible to control the operation of the boiler 20 on the basis of measurements made by the sensors 48 , 50 . In this respect, the control unit 46 determines the difference between the temperature of the hot air entering into the chamber 34 and the outside temperature, and compares it to a predetermined threshold value. If the temperature difference is below the threshold value, an alarm signal that can be visual or audible is triggered by the control unit 46 to signal a failure of the operation of the boiler 20 . As a variant, the control unit 46 can drive the operation of the boiler 20 so as to maintain the difference between the temperature of the hot air entering into the chamber 34 and the outside temperature at a fixed value.
[0050] In the embodiment described, the operation of the boiler is controlled and/or driven on the basis of the temperature measurements of the hot air introduced into the chamber 34 and of the outside air. It will be understood that it is also possible, without departing from the framework of the invention, to provide for the mounting of one or more temperature sensors directly inside the chamber 34 replacing the temperature sensor of the hot air mounted in the duct 37 . In the case of a plurality of temperature sensors mounted in the chamber 34 in different places, it is possible to provide for the control unit 46 to calculate an average of the measured temperatures in order to obtain a value representative of the temperature of the walls of the chamber 34 .
[0051] In a variant embodiment, it is also possible to determine the temperature of the chamber 34 by means of charts or maps stored in the control unit 46 and obtained from previous trials on the basis of temperature measurements on the hot air introduced inside the latter, of the temperature of the outside air, and of the speed of the vehicle 16 to which the system 10 is attached.
[0052] Alternatively, it is also possible to provide for the control unit 46 to drive the operation of the boiler 20 , and therefore that of the emission means 22 , only as a function of the temperature of the chamber 34 determined by the sensor or sensors, i.e., without considering the temperature of the outside air.
[0053] In the embodiments described, the sensor or sensors provided for measuring the temperature of the hot air in the duct 37 or in the chamber 34 are temperature sensors. Alternatively, to measure the temperature of the chamber 34 or of the air inside the duct 37 , it could be possible to provide a thermal analysis infrared sensor able to detect the infrared radiation emitted and convert it into an electrical signal in order for the control unit 46 to determine the temperature of the chamber 34 or of the air inside the duct 37 .
[0054] When the system 10 is intended for use at altitude, for example above 1500 meters, it is possible to provide, in addition, an atmospheric pressure sensor (not represented) mounted on the shielding 24 and directly connected to the boiler so as to be able to regulate its combustion according to the density of the air to be burned, which reduces with altitude.
[0055] The means 22 makes it possible to obtain, continuously, at the level of the chamber 34 , a temperature substantially greater than that which can be obtained with other technologies with comparable supplied energy, which makes it possible to generate a significant temperature difference with the outside temperature so as to be able to be detected equally by a mine arranged at the roadside and by an improvised explosive device, and to do so even when the speed of displacement of the vehicle 16 is relatively high, of the order of 50 kilometers per hour. Furthermore, with the system 10 , a relatively short temperature rise time of the chamber 34 is obtained and the system can operate autonomously for several tens of hours at a stretch. It is, moreover, relatively compact and lightweight.
[0056] In the application described, the system 10 is pushed by a following vehicle 16 . It will easily be understood that this vehicle 16 can be a transport vehicle or else a remotely-operated vehicle. As indicated previously, the system 10 is particularly suitable for the decoying of mines or improvised explosive devices. The system can, however, be used for other applications, for example for decoying infrared airborne missiles.
[0057] Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as examples of embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.
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The decoy system, notably for terrestrial mines or improvised explosive devices, includes: a means of producing heat energy including an air or water boiler, a means of emitting radiation in the infrared spectrum including a chamber that is fed with fluid by the production means, the chamber being provided with internal fins able to promote a build-up of heat energy inside said chamber, at least one detection means for determining the temperature of the chamber or the temperature of the fluid between the production means and the emission means, and a control unit able to control the operation of the heat energy production means at least according to the determined temperature.
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This is a division, of application Ser. No. 301,603, fled Oct. 27, 1972, now U.S. Pat. No. 3,904,187.
BACKGROUND OF THE INVENTION
The present invention relates to the folding of sheet-material blanks and more particularly to a method and an apparatus for effecting such folding.
Sheet-material blanks must frequently be folded, for instance to form a signature in a book, brochure or the like. Such folding is ususally carried out by means of a longitudinal or transverse folding device associated with so-called rotary folders of the type used in various rotary printing machines which use sheet material. As a rule, these folding devices use a conically or analogously convergent guide in which the sheet material blank is made to advance whereby it becomes progressively folded. Another approach known from the art is to use transverse folding cylinders. In some instances, where the fold must be carried out with particular accuracy, so-called knife-folders are employed. These "knives" are folding elements which are guided to perform a movement during which they engage the respective sheet material blank and fold it. It is known to guide the knife in a straight-line guide or to articulate it to a swingable arm.
The problem with these latter types of folders is the drive for the movement which is to be performed by the knife, particularly if the knife is required to form a fold on a large-format sheet-material blank. This means that the knife must pass through a relatively significant stroke, and of course in modern equipment the high-speed operation of the machines necessitates that the number of strokes be correspondingly great. This means that a cam control of the knife movement, the inherently ideal way of controlling the movement, is no longer possible. It has already been attempted to effect the control by means of electromagnetic units. These last two types of drive arrangements have the disadvantage that the number of strokes which is required in modern machines per unit of time, cannot be achieved. Moreover, the drives accelerate the knife or deflecting element in such a manner that it engages the respective sheet-material blank in shock-like manner, a disadvantage in terms of the accuracy of folding which can be obtained.
Some improvement was obtained in this field by using straight-line articulated crank linkages. Such crank linkages are driven and the output member of the linkage is associated with the knife which it then moves in a straight line. The difficulty with these arrangements is that the speed of movement of the last element, that is here the knife, decreases significantly long before the knife reaches the end of its working stroke. This means that that the sheet-material blank engaged by the knife receives only a relatively brief but very strong impulse deflecting it out of the path in which it travels, but is not positively guided subsequently because of the progressive retardation in the speed of advancement of the knife. Thus, the deflected portions of the sheet-material blank will slide more or less freely under the impulse initially imparted to them by the knife, in the direction in which they have been deflected by the knife, before they are engaged by the folding rollers which then complete the folding operation. In many instances, however, the sheet-material blanks have already previously been folded by means of conical folding guides or other devices, so that they are of V-shaped configuration, that is they are already bi-folded in one direction. This means that at the opposite sides of the sheet-material blank, that is at the opposite lateral edges thereof, different stiffness and friction coefficients exist. This, in turn, means that as soon as the blank is no longer positively guided by contact with the knife, it will tend to shift its configuration and position and depending upon the mass and the speed of the initial impulse imparted to it, it will reach the folding rollers at some angle of inclination. This, as is well known to thse conversant with the art, results in various types of difficulties.
SUMMARY OF THE INVENTION
It is, accordingly, an object of the present invention to avoid the disadvantages of the prior art.
More particularly it is an object of the present invention to provide an improved folding apparatus for folding of sheet-material blanks, which is not possessed of the aforementioned disadvantages.
Another object of the invention is to provide an improved method of effecting the folding of sheet-material blanks.
In pursuance of these objects, and of others which will become apparent herefter, one feature of the invention resides in guiding a sheet-material blank in a predetermined path, and advancing a deflecting element (e.g. a folding knife) at relatively slow speed from one side of the path toward and into engagement with the blank. Thereupon, the deflecting element is accelerated and simultaneously advanced together with portions of the blank out of the path and to the opposite side of the latter, where such portions can be engaged by the folding rollers. According to the invention the acceleration of the deflecting element assures that it will always be in positive guiding engagement with the deflected portions of the sheet-material blank so that the disadvantages of the prior art cannot occur.
The apparatus for carrying out the novel method is capable of producing at high speed and can therefore be employed to economic advantage. The invention is applicable both to transverse folders and to longitudinal folders, that is apparatuses which effect transverse or longitudinal folding of sheet material blank. It assures that the deflecting element engages the sheet-material blank at low speed, rather than to impart a strong impulse thereto. Once the blank has been engaged, the deflecting element is accelerated together with the blank and the latter is thus being positively guided by continued engagement with the deflecting element until the deflected portions of the sheet-material blank have reached a position in which they can be engaged by the folding rollers.
According to a currently preferred embodiment of the invention we utilize an articulated crank linkage which drives the deflecting element in a straight-line path, and whose movemment is in turn controlled by so-called anti-parallel crank linkages. The output member of the anti-parallel crank linkage is at one and the same time also the input member of the straight-line crank linkage arrangement. However, it is also possible to use, in place of the anti-parallel crank linkages, elliptically configurated wheels.
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 acompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a somewhat diagrammatic side view illustrating one embodiment of the invention;
FIG. 2 is a graph comparing the characteristics of movement of the deflecting element in an apparatus according to the present invention and in accordance with the prior art; and
FIG. 3 is analogous to FIG. 1 but illustrating a further embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Discussing firstly the embodiment in FIG. 1 it will be seen that reference numeral 1 designates a somewhat diagrammatically illustrated rotatable drive shaft 1 which drives a crank 2 which, together with a coupling element 3, a crank 4 and a fixed element 5 constitutes a counter-motion anti-parallel crank drive in which during rotation of the crank 2 in one direction the crank 4 connected thereto by the coupling element 3 rotates in the opposite direction of rotational speeds different from those of the crank 2. In accordance with the present invention the crank 4 is the output element of the anti-parallel crank drive, but at the same time is also the input or drive crank of the straight-line crank linkage arrangement which, in addition to the crank 4, has the coupling element 6, the glide rod 7 which carries at its front the deflecting element 9, and the straight-line guide 8.
Reference numeral 11 identifies a guide having the illustrated slot which registers with the nip 14 and find between two folding rollers 13 and 12 which rotate in mutually opposite directions as illustrated by the associated arrows. The sheet-material blanks 10, of which one is shown, advance on this guide 11 in a predetermined path, defined by the surface of the guide 11 which faces upwardly in FIG. 1. They move across the gap in the guide 11 and it will be understood that they have previously been severed from endless webs of sheet material, that they may have been printed or otherwise processed, that they may have been folded longitudinally and/or transversely and that there may be more than one of these blanks 10 provided on the guide 11 in overlying relationship. In other words, it is possible to fold two or more of the blanks 10 simultaneously.
It is clear that when the element 9 moves from one side of the path (the upper side in FIG. 1) across the path to the other side (the lower side in FIG. 1), it deflects the blank 10 as illustrated through the slot in the guide 11. Depending upon the length of the stroke required to be performed by the element 9, the coupling element 6 may be pivoted at a pivot 15 or if maxiumum stroke length is required, at the pivot 16 which in any case exists and connects the coupling element 3 with the crank 4. It is also possible, however, to provide an arrangement in which the pivot 15 can be shifted on the crank 4 in order to permit the stroke length to be varied if and as required.
If the arrangement uses only a single straight-line crank linkage arrangement, for instance that illustrated in FIG. 1 and comprising the crank 4, the coupling element 6, the rod 7 and the guide 8, as is known from the prior art, then the element 9 will be undergoing only insignificant acceleration at the time it contacts the blank 10 at point A 1 (see FIG. 2), as indicated by the solid line in FIG. 2, The acceleration which the element 9 has at the time it contacts the blank 10 at point A 1 , is maintained over only a short period S 1 until the point E 1 is reached. FIG. 2 shows clearly that the speed of the element 9 decreases quite rapidly in the direction towards the point E 1 , so that the deflected blank 10 is no longer being positively guided by engagement with the element 9 and will be able to move relatively freely (without guidance) in the direction towards the nip 14 (FIG. 1).
Relatively expensive attempts have been made to overcome this problem in the art, for instance to retard the blank 10 by brake or friction rollers located above the guide 11, so as to prevent the free movement of the deflected portions of the blank, that is movement which is continued at the initial speed of deflection whereas the element 9 is progressively retarded. Even this, however, has been of no help in the prior art and especially due to the fact that the blanks 10 have usually already been previously folded one or more times, the problems occur which have been outlined above, as soon as the non-positively guided blank is then engaged by rollers 12 and 13.
The present invention, however, avoids these difficulties. FIG. 2 shows that during the working stroke of the element 9 there is obtained a distance-speed relationship as is indicated by the broken line 21 in FIG. 2. It will be noted that the element 9 engages the blank 10 at point A 2 with relatively low speed and that it then accelerates the blank increasingly until it extends substantially beyond the guide 11; the acceleration of the element 9 and consequently of the blank 10 is terminated only when the nip 14 has almost been reached, that is it is terminated almost at point E 2 where the working stroke of the element 9 ends. This means that the difficulties inherent in the prior art have been avoided, because any undesired displacement of the blank 10 is no longer possible because it has already been engaged by the rollers 13 and 14 and is positively guided by them.
If, in accordance with the prior art, only a straight-line crank linkage drive is utilized, guidance of the blanks 10 can be effected only in the region s 1 of FIG. 2, that is between the point of contact A 1 which is reached at almost maximum speed and the point E 1 . In contradistinction thereto, the present invention makes it possible to positively guide the blank 10 over a substantially longer distance s 2 , extending between the contact point A 2 which is reached at relatively low speed of the element 9, and the point E 2 which is almost coincident with the end of the working stroke of the element 9. This means that at identical angular speed of the respective crank drive and at better utilization of the operating rhythm, an improvement of the folded blanks, that is the quality of the folds thereof, is obtained with the present invention. This is obtained by having the movement of the element 9, and therefore the deflection of the blank 10, be continuous in accordance with the present invention and by guiding the blank 10 positively from the moment it is deflected out of its path until it is engaged by the rollers 12 and 13 at the nip 14 thereof.
In FIG. 3 we have illustrated a further embodiment of the invention. Like reference numerals identify the same components as in the emodiment of FIG. 1. Here, however, we have illustrated that in place of the anti-parallel cranks 2-5 it is possible to mount on the drive shaft 1 an elliptical wheel 17 which cooperates with an elliptical wheel 19 of identical size and which is mounted for rotation on a shaft 18. The spacing of the axis of the shaft 18 from the axis of the shaft 1 corresponds to the distance of the fixed points of articulation of the member 5 of the embodiment in FIG. 1. The coupling member 6 would then have to be articulated on the large elliptical axis of the wheel 19. The data given in FIG. 2 with respect to the operation of the embodiment of FIG. 1, and the comparison with the prior art which is provided in FIG. 2, hold identically true with respect to the embodiment of FIG. 3.
It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.
While the invention has been illustrated and described as embodied in an apparatus for folding sheet-material blanks, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.
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 and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.
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A sheet-material blank is advanced in a path and from laterally of the path a folding member is advanced slowly towards and into engagement with the blank, whereupon it is accelerated beyond the path to the other side thereof. The deflecting member is then withdrawn and the deflected portions of the blank are engaged between two rollers which rotate in mutually opposite directions and the blank is thereby folded by engagement with these rollers through the nip of which it passes.
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