PATENT ABSTRACT
A dual-nature, uni-constructed device, suitable for conducting electricity between two objects in relative motion, comprises two compatible elements each having a straight section and a sinuous section. The two elements are combined to form a unified whole whereby the two straight sections are mutually servable as a brush component and the two sinuous sections are mutually servable as a spring component. The inventive device is associable with an electrical or electromechanical machine so that, during machine operation, the brush component slidingly contacts a first machine part, the spring component is affixed to a second machine part and exerts a bias against the brush component, and the inventive device conducts electrical current from one machine part to the other machine part. Each element includes an electrically conductive main layer (including one or more wire fabric sheets) and two elastomeric outside layers (on opposite sides of the sinuous section).

PATENT DESCRIPTION
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is related to U.S. nonprovisional application Ser. No. 10/863,844, filed 3 Jun. 2004, hereby incorporated herein by reference, entitled “Electrical Current Transferring and Brush Pressure Exerting Interlocking Slip Ring Assembly,” joint inventors William A. Lynch, Wayne Marks, Jr. and Neal A. Sondergaard. 
   This application is related to U.S. nonprovisional application Ser. No. 10/985,074, filed 5 Nov. 2004, hereby incorporated herein by reference, entitled “Solid and Liquid Hybrid Current Transferring Brush,” joint inventors Neal A. Sondergaard and William A. Lynch. 
   This application is related to U.S. nonprovisional application Ser. No. 10/985,075, filed 5 Nov. 2004, hereby incorporated herein by reference, entitled “Folded Foil and Metal Fiber Braid Electrical Current Collector Brush,” joint inventors William A. Lynch, Neal A. Sondergaard and Wayne Marks, Jr. 
   This application is related to U.S. nonprovisional application Ser. No. 11/033,619, filed 13 Jan. 2005, hereby incorporated herein by reference, entitled “Quad Shaft Contrarotating Homopolar Motor,” joint inventors William A. Lynch and Neal A. Sondergaard. 
   This application is related to U.S. nonprovisional application Ser. No. 11/250,698, filed 8 Oct. 2005, hereby incorporated herein by reference, entitled “Ion Conducting Electrolyte Brush Additives,” joint inventors William A. Lynch and Neal A. Sondergaard. 
   STATEMENT OF GOVERNMENT INTEREST 
   The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without payment of any royalties thereon or therefor. 
   BACKGROUND OF THE INVENTION 
   The present invention relates to machinery involving the conduction of electrical current between parts moving relative to each other, more particularly to methods and devices for effecting or facilitating such electrical conduction. 
   Various kinds of motors, generators and other electrical apparatus require the conduction of electricity between two relatively moving parts. Such mechanical arrangements usually involve the conduction of current between a stationary part (stator) and a rotating part (rotor). A device known as a “brush” or “current collector” is normally used for making sliding contact between stationary and rotating parts so as to conduct electrical current therebetween. 
   Depending on the particular machinery, a brush can be used to conduct current in either direction (i.e., either from the stationary part to the rotating part, or vice versa), and can be fixed with respect to either the rotating part or the stationary part. Among the desirable qualities of a brush are high current-carrying capacity (e.g., in terms of capability of carrying a high amount of current per unit area of the interface between the brush and the surface contacted thereby), low friction, and high wear resistance. Current collection brush technology has grown in interest with the advent and continued development of homopolar machine technology, particularly in the realm of homopolar motors (which operate on direct current) such as those that are currently envisioned for naval ship propulsion. 
   Conventional brushes include solid carbon brushes, copper fiber brushes and liquid metal brushes. The majority of brushes currently used are of the solid carbon variety. Solid carbon brushes provide limited power densities due to their characteristically small number of contact spots. In addition, solid carbon brushes tend to have a short life and to produce conductive wear debris, resulting in frequent brush replacement and frequent machinery cleaning and associated high maintenance costs. Generally speaking, as compared with solid carbon brushes, copper fiber brushes are considered to afford superior performance; however, copper fiber brushes are currently expensive to produce and can support only moderate current densities. It is generally believed that liquid metal brushes are capable of supporting very high current densities, but more research is needed in this area because of problems concerning stability and reactivity. 
   A conventional current collection assembly includes a brush and a “holder” (for the brush) as two separate components that are attached to each other. The holder is also attached to either the stationary part or the rotating part of the machinery. Soldering is normally implemented to achieve attachment between a brush and a holder. Small voltage drops are associated with solder joints, which can thus adversely affect performance. Moreover, solder joints are prone to mechanical failure. 
   SUMMARY OF THE INVENTION 
   In view of the foregoing, it is an object of the present invention to provide an improved current collection device. 
   As typically embodied, the present invention&#39;s device comprises two congruous elements, equal in length, each element having two ends. Each element includes a longitudinally straight section (which extends from the first end) and a longitudinally sinuous section (which extends from the second end). The elements are contrapositionally coupled so that: The straight sections (which are equal in length) adjoin; the first ends are even; the second ends adjoin; and, the sinuous sections (which are equal in length) are oppositely undulate. Each element includes an electrically conductive wire fabric (or a group of adjoining electrically conductive wire fabrics) and an elastomeric coating. According to typical inventive practice, each electrically conductive wire fabric is made of a suitable metal elemental material (such as copper, silver, or gold or another metal) or a suitable metal alloy material (such as including copper, silver, and/or gold and/or another metal). In each element: The electrically conductive wire fabric extends from the first end to the second end; the elastomeric material covers a portion of the outside surfaces (including both the inward facing and outward facing surfaces) of the electrically conductive wire fabric (or the group of adjoining electrically conductive wire fabrics), the elastomeric coating being predominately in the sinuous section; a solder material infuses a portion of the electrically conductive wire fabric (or the group of adjoining electrically conductive wire fabrics), the solder material-infused portion being in the sinuous section in the vicinity of the second end. The lower outside surface of the solder-infused portion is not covered by the elastomeric material, but instead is contactingly covered by an electrically conductive (e.g., metal) plate that facilitates electrical conductivity. 
   According to typical practice of the present invention, the two solder-infused portions of the respective sinuous sections of the two elements adjoin each other (e.g., are connected to or proximate to each other) so as to together form a solder-based electrical contact, which according to typical embodiments includes electrically conductive plating that covers the bottom surface of the two adjoining solder-infused portions. Further according to typical inventive practice, in each element a cement material infuses a portion of the electrically conductive wire fabric (or the group of adjoining electrically conductive wire fabrics), the cement-infused portion being in the sinuous section adjacent to the solder-infused portion. The two respective cement-infused portions thus barricade the solder-based electrical contact (which is formed by the two respective solder material-infused portions) so as to prevent infiltration of the solder material into other portions of the respective elements. The inventive device is securable at the solder-based electrical contact with respect to machinery so that: The straight sections together constitute a brush for contacting (at the first ends) a machinery part that moves relative to the inventive device; the electrically conductive plate that contiguously covers the solder-based electrical contact is in abutting physical contact with another machinery part, viz., a machinery part that is fixed with respect to the inventive device; and, the sinuous sections together constitute a spring for biasing the straight sections toward the contacted relatively moving machinery part. 
   The spring-like nature of the sinuous sections is associated with a reduction in the length of the elements (and hence of the inventive device) when the inventive device is secured at the solder-based electrical contact with respect to the machinery. According to many of the present invention&#39;s current collection applications, the two relatively moving machinery parts are a stationary part and a moving (e.g., rotating) machinery part; depending on the inventive embodiment, the contacted machinery part is either a stationary part or a moving (e.g., rotating) machinery part. The inventive device is securable at the solder-based electrical contact with respect to either a stationary machinery part (if the contacted machinery part is a moving part) or a moving machinery part (if the contacted machinery part is a stationary part) so that the elements together constitute an electrical conductor between the stationary machinery part and the moving machinery part. In accordance with some embodiments of the present invention, the two relatively moving machine parts are both moving (e.g., rotating) parts; for instance, the present invention can be practiced in association with contra-rotating machines in which both relatively moving parts rotate. The electrically conductive (e.g., gold, silver or other metal) plate (e.g., plating such as electroplating), which is attached to the solder-infused metal fabric and thereby made part of the solder-based electrical contact, serves to facilitate electrical conduction between the inventive device and the machine part with respect to which the inventive device is secured. 
   The present invention&#39;s device is normally practiced as a current collection device that serves as an electrically conductive bridge or conduit between two bodies in motion relative to each other, the inventive device effecting fixed electrical connection with respect to one of the bodies and effecting sliding electrical connection with respect to the other of the two bodies. The inventive current collection device represents a unitary combination that includes, in purpose and effect, both a brush and a bias-producing holder-analogue for the brush. The present invention is thus typically embodied as a combined, one-piece current collector that represents a kind of integrated “brush-plus-holder” device. The “spring” component of the inventive device is analogous to the holder of a conventional current collection assembly that includes a brush and a holder as two discrete parts, the holder being attached to an object as well as to the brush (thereby holding the brush in place). The inventive device&#39;s “brush” component represents a structurally continuous extension of the inventive device&#39;s spring component. 
   The inventive current collection device lacks a mechanical joint of any kind (e.g., a solder joint) for joining the inventive brush component with the inventive spring component, since they are intrinsically joined together as one. According to many inventive embodiments, no mechanical joint (e.g., solder joint) is required in the fabrication process of an inventive device. The inventive brush component and the inventive spring component are structurally continuous parts of the inventive unitary construction. Because of the present invention&#39;s obviation of attachment (e.g., solder-type attachment) between the present invention&#39;s brush component and the present invention&#39;s “spring” component, the present invention affords greater mechanical stability as well as greater electrical stability. The inventive device is less prone to mechanical failure associated with the utilization of one or more solder joints amidst a conventional current collection assembly. Furthermore, because of the relatively low mass of the inventive device as typically embodied, the inventive device is less prone to voltage fluctuation than is a conventional, more massive, brush-holder device. 
   The present invention can be used in practically any application involving relatively moving parts of a machine (e.g., an electrical machine or an electromechanical machine), including but not limited to applications involving motors (e.g., homopolar motors), generators (e.g., homopolar generators), commutators, etc. A typical brush component in accordance with the present invention is narrowly proportioned and thus, advantageously, may be characterized by low losses of magnetic circulating currents. Because the electrically conductive fibrous elements of a typical inventive device are less independent than are the electrically conductive fibrous elements in a conventional fiber brush, higher losses of electrical conduction (both in the electrically conductive elements and in the interface at which the brush makes sliding, frictional contact with a relatively moving object) may be associated with some embodiments of inventive practice than may be associated with some embodiments of conventional practice. 
   Other objects, advantages and features of the present invention will become apparent from the following detailed description of the present invention when considered in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described, by way of example, with reference to the accompanying drawings, wherein: 
       FIG. 1  is a longitudinally sectional front elevation view of a typical embodiment of an integral current collection device in accordance with the present invention, particularly illustrating the partially linear, partially curvilinear configuration of the inventive device. 
       FIG. 2  is a side elevation view of the inventive device shown in  FIG. 1 . 
       FIG. 3  is a bottom plan view, oriented sideways, of the inventive device shown in  FIG. 1 , with certain exterior layer portions peeled back to reveal corresponding interior layer portions. 
       FIG. 4  is a partial version of the bottom plan view shown in  FIG. 3  of the inventive device shown in  FIG. 1 , the solder-infused contact section being removed so as to reveal inward facing surfaces of the inventive device. 
       FIG. 5  is a top plan view, oriented sideways, of the inventive device shown in  FIG. 1 . 
       FIG. 6  and  FIG. 7  are each a view, similar to the view shown in  FIG. 1 , illustrating use of the inventive device shown in  FIG. 1  in machinery in association with machine parts including a rotor and a stator. 
       FIG. 8  is a plan view of a planar (unbent) rectangular piece of electrically conductive wire fabric suitable for inventive practice. 
       FIG. 9 ,  FIG. 10  and  FIG. 11  are each a partial and enlarged view of the wire fabric shown in  FIG. 5 .  FIG. 9  depicts a biaxially braided wire fabric construction.  FIG. 10  depicts a triaxially braided wire fabric construction.  FIG. 11  depicts a wire fabric construction of plural (e.g., multiple) parallel bonded elongate members, each elongate member representing a braid-like grouping of plural individual wire strands, fibers or filaments. 
       FIG. 12 ,  FIG. 13 ,  FIG. 14  and  FIG. 15  are each a schematic of an embodiment of an inventive method for fabricating an inventive device. 
       FIG. 16  is a perspective view (by way of photographic image) of an embodiment of a braid brush in accordance with the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Reference is now made to  FIG. 1  through  FIG. 5 , which show a typical embodiment of an integral, dual-component, current collection device  100  in accordance with the present invention. The present invention&#39;s current collection device  100  includes two partially linear, partially sinuous elements representing equal and opposite halves of inventive device  100 , viz., an element  12   a  (on the lefthand side as shown in  FIG. 1 ) and an element  12   b  (on the righthand side as shown in  FIG. 1 ). Imaginary vertical geometric plane v bisects inventive device  100  into element  12   a  and element  12   b , which are congruous and oppose each other so as to represent mirror images of each other when viewed as depicted in  FIG. 1 . Inventive device  100  is thus characterized by a left-right symmetry, as illustrated in  FIG. 1 , that is exhibited in complementary fashion by elements  12   a  and  12   b  with respect to vertical geometric plane v. 
   Each element  12  is characterized by the same overall vertical length L and two ends  13 . End  13   a   1  is the upper end of element  12   a ; end  13   a   2  is the lower end of element  12   a ; end  13   b   1  is the upper end of element  12   b ; end  13   b   2  is the lower end of element  12   b . Each element  12  includes a straight section  20  and a sinuous section  30 . In each element  12 , the overall vertical length L equals the sum of the straight section  20 &#39;s vertical length L STR  plus the sinuous section  30 &#39;s vertical length L SIN . Not only overall length L, but also straight section length L STR  and sinuous section length L SIN , are the same in each element  12 . Vertical length L effectively represents the axial length, taken along vertical plane v, of inventive device  100 . Straight section  20   a  is longitudinally delimited by upper end  13   a   1  and horizontal geometric plane h. Straight section  20   b  is longitudinally delimited by upper end  13   b , and horizontal geometric plane h. Sinuous section  30   a  is longitudinally delimited by lower end  13   a   2  and horizontal geometric plane h. Sinuous section  30   b  is longitudinally delimited by lower end  13   b   2  and horizontal geometric plane h. Sinuous sections  30   a  and  30   b  are largely separated from each other, but converge at lower ends  13   a   2  and  13   b   2  as well as in the vicinity of horizontal geometric plane h, which is shown in  FIG. 1  to approximately intersect the bottom end of junction  23 . Lower ends  13   a   2  and  13   b   2  meet at vertical geometric plane v, and junction  23  coincides with vertical geometric plane v. 
   Each straight section  20  includes a flat or substantially flat surface  21 . The straight sections  20   a  (of element  12   a ) and  20   b  (of element  12   b ) adjoin each other, surface  21   a  (of the core  14   a  portion of straight section  20   a ) to surface  21   b  (of the core  14   b  portion of straight section  20   b ), so as to form a junction  23 . According to typical inventive practice, surfaces  21   a  and  21   b  are adhered to each other at junction  23  via a cement or other adhesive material  29 , such as shown in  FIG. 5 . As shown in  FIG. 1 , junction  23  is coincident with geometric plane v and is intermediate the corresponding surfaces  21   a  (of straight section  20   a ) and  21   b  (of straight section  20   b ). Straight sections  20   a  and  20   b  have the same length and adjoin so that upper ends  13   a   1  and  13   b   1  are even with each other, thus affording a continuous or substantially continuous upper edge face  25  that is suitable for contacting an object moving relative to inventive device  100 . 
   The “violin” shape of the inventive device  100  illustrated in  FIG. 1  through  FIG. 5  is but one of diverse shapes that are possible for practicing the present invention. As exemplified by the shown elements  12   a  and  12   b , most inventive embodiments will be characterized by a plural number of undulations (waves) for each of two partially straight, partially undulating (wavy) elements  12 , wherein the elements&#39; corresponding undulations are equivalent and opposite. Each undulation roughly describes a “U”-shape having its closed, bent end distanced from vertical geometric plane v and its open end proximate vertical geometric plane v. The undulating profile shown in  FIG. 1  reveals two undulations, each having (at the closed, bent end of its “U”-shape) a crest  35 , wherein a trough  37  is situated between the crests  35 . Although each element  12  is shown in  FIG. 1  to describe two undulations having congruently or approximately congruently curved shapes in terms of wavelength (measured, e.g., as the longitudinal distance between trough  37  and an end  13 ) and amplitude (measured, e.g., as the perpendicular distance between plane v and crest  35 ), such congruency between or among the undulations of each element  12  is not a requirement for inventive practice. 
   Each element  12  includes an electrically conductive core  14  and an electrically nonconductive covering or coating  16 . In each element  12 , the core  14  represents the main “structural” portion of element  12 . According to usual inventive practice, core  14  is composed of copper or silver or gold or another electrically conductive metal, or is composed of a metal alloy that includes copper and/or silver and/or gold and/or one or more other electrically conductive metals. Also according to usual inventive practice, covering  16  is composed of a natural rubber, or synthetic rubber (e.g., a silicone rubber), or other elastomer. Element  12   a  includes metal core  14   a  and elastomeric covering  16   a , and element  12   b  includes metal core  14   b  and elastomeric covering  16   b . To elaborate, in each element  12  the straight section  20  includes a portion of core  14  but excludes or substantially excludes elastomeric material; that is, the portion of core  14  that is in each straight section  20  is uncovered or substantially uncovered with elastomeric material  16 . The core  14  portion of each straight section  20  is thus exposed (or substantially exposed) to permit direct moving contact, frictional to some degree, with a machine part during operation of machinery with which inventive device  100  is associated. Further, in each element  12 , the sinuous section  30  includes a portion of core  14  and also includes elastomeric material  16 ; that is, a significant portion of core  14  that is in each sinuous section  30  is covered with elastomeric material  16 .  FIG. 1  represents a longitudinal section of inventive device  100  because the elastomeric material  16  covers not only the outwardly and inwardly facing surfaces, but also the edges  27 , of sinuous sections  30 . 
   Each sinuous section  30  includes a solder material-infused portion  70  and a cement material-infused portion  80 . Solder-infused portion  70  is bounded on one end by vertical geometric plane v (where lower ends  13   a   2  and  13   b   2  meet) and on the other end by cement-infused portion  80 . In the solder-infused portions  70   a  and  70   b , the corresponding portions of metal cores  14   a  and  14   b  are both impregnated with a solder material  71  (which is absorbed into the metal fabric core  14  material) in order to help establish an electrical contact region  700 , which is a continuum (or near-continuum) formed in part by the combined adjacency of solder-infused portions  70   a  and  70   b . Solder-infused portions  70   a  and  70   b  combine, contiguously or nearly contiguously, to form an overall solder-infused portion of device  100 , viz., overall solder-infused portion  701 . Electrical contact region  700  includes not only the overall solder-infused portion  701  (which consists of the two adjacent solder-infused portions  70   a  and  70   b ), but also includes, in abutting contact with the overall solder-infused portion  701 , an electrically conductive plating (e.g., electroplating)  90 . In the cement-infused portions  80   a  and  80   b , the corresponding metal cores  14   a  and  14   b  are each impregnated with a cement material  81  (which is absorbed into the metal fabric core  14  material) in order to establish a barrier for preventing solder wicking into areas of inventive device  100  other than electrical contact region  700 . Each sinuous section  30  is covered with elastomeric material  16 , with the exception of the outward (downward) facing surface of solder-infused portion  70 . The bottom surface of electrical contact region  700  is provided not by an elastomeric material  16  but rather by the exposed electrically conductive plating  90 , which serves to improve the efficiency of the electrical contact and to prevent corrosion. 
   Still referring to  FIG. 1  through  FIG. 5 , and also referring to  FIG. 6  and  FIG. 7 , inventive device  100  can be considered to be divided into two structurally and functionally different components, viz., “brush” component  200  (the upper component as shown in  FIG. 1 ) and “spring” component  300  (the lower component as shown in  FIG. 1 ), which together form an integral whole, viz., inventive device  100 . Imaginary horizontal geometric plane h is drawn in  FIG. 1  as an approximate demarcation between brush component  200  and spring component  300 . The spring component  300  shown in  FIG. 1  bears some similarity, both structurally and functionally, to the “serpentine-shaped spring device” disclosed by William A. Lynch and Neal A. Sondergaard (the present inventors), et al., at U.S. Pat. No. 6,628,036 B1, issued 30 Sep. 2003, entitled “Electrical Current Transferring and Brush Pressure Exerting Spring Device,” said patent incorporated herein by reference. 
   Brush component  200  includes straight sections  20   a  and  20   b , which are connected to each other in abutting fashion. Spring component  300  includes sinuous sections  30   a  and  30   b , which are connected to each other end-to-end at respective lower ends  13   a   2  and  13   b   2 . Elements  12   a  and  12   b  together constitute a dual function unit  100  wherein the connected straight sections  20   a  and  20   b  together constitute a brush component  200  for making sliding, frictional contact (at upper ends  13   a   1  and  13   b   1 ) with a machine part that moves relative to inventive device  100 , and wherein the connected sinuous sections  30   a  and  30   b  together constitute a spring component  300  for biasing brush component  200  toward the machine part that is contacted by brush component  200 . 
   Brush component  200  includes a flat or substantially flat upper edge surface, viz., brush face  25 , which is formed by the combination of the corresponding upper edge surfaces of elements  12   a  and  12   b  at upper ends  13   a   1  and  13   b   1 . Brush face  25  represents the area of brush component  200  that makes contact with the moving part of a machine such as the “machinery”  50  shown in  FIG. 6  and  FIG. 7 . Brush face  25  is characterized by an “aspect ratio,” defined herein in relation to  FIG. 5  as W/T, i.e., the ratio of the width W of brush face  25  to the thickness T of brush face  25 . The inventive practitioner may wish to change the aspect ratio of brush face  25  in order to suit particular applications; in this regard, the width W and/or the thickness T of brush face  25  can be varied, for instance in terms of numbers, thicknesses, and/or widths of electrically conductive sheets  40 . 
   The brush component  200  illustrated in  FIG. 5 , which has four electrical conduction sub-layers (sheets)  40 , is rather narrow (i.e., has a relatively high aspect ratio) and should therefore afford very low magnetic circulating current losses. On the other hand, because the wires  41  (such as wires  41  shown in  FIG. 9  through  FIG. 11 ) of a typical inventive device  100  are less independent than are the electrically conductive fibers in a conventional fiber brush, inventive practice may be susceptible to higher electrical conduction losses in wires  41  as well as in interface  59 . Performance characteristics (such as power loss and wear rate) may need to be tested for given inventive devices  100  in order to establish their efficacy for given applications. 
   In  FIG. 6 , inventive device  100  is mounted upon stator  54 , and stationary brush component  200  contacts rotor  52  at interface  59 ; in  FIG. 7 , inventive device  100  is mounted upon rotor  52 , and rotating brush component  200  contacts stator  54  at interface  59 . In either arrangement, interface  59  is a surface portion that is constantly moving in accordance with the rotation of rotor  52 , which rotates in a rotational direction r about a rotational axis (such as rotational axis  55  shown in  FIG. 6 ). Electrical contact region  700  represents an electrical contact area between inventive device  100  and the machine part with which inventive device  100  is fixedly coupled. The metal plate (e.g., plating)  90  of the inventive device  100 &#39;s electrical contact region  700  is in direct, fixed, physical contact with a surface region of the machine part with which inventive device  100  is fixedly coupled. According to some inventive embodiments, the machine part&#39;s fixedly contacted surface region (corresponding to electrical contact region  700 ) includes metal (e.g., gold or silver) plating, which abuts the inventive device  100 &#39;s metal (e.g., gold or silver) plate  90 . Such a plate-on-plate configuration may be particularly efficacious in terms of electrical contact efficiency and corrosion prevention. 
   Inventive device  100  is shown to be mechanically secured (to stator  54  in  FIG. 6 ; to rotor  52  in  FIG. 7 ) via one or more leaf springs  57 . A “leaf spring” is but one type of diverse mechanisms that can be used in inventive practice for mounting, clamping, or otherwise attaching or affixing the inventive device  100  with respect to the electrically conductive object (stator  54  in  FIG. 6 ; rotor  52  in  FIG. 7 ) that is to be fixedly joined with inventive device  100 . A typical leaf spring  57  is essentially a flat, rigid structure (made, e.g., of stainless steel or other material, which need not be electrically conductive) that in its natural state is moderately curved upward at its ends, which are not shown in  FIG. 6  and  FIG. 7 . At least one leaf spring  57  can be used for clamping an inventive device  100  to an object. The leaf spring  57  is positioned, concave upward, so as to adjoin the portion of the elastomeric layer  16  that is located on the upper side of the electrical contact region  700 . While the inventive device  100  is in place relative to the object, the two ends of the leaf spring  57  are pushed or bent downward (toward the object), thereby facilitating attachment at the two ends of the leaf spring  57  to the object. This attachment to the object at the two ends of the leaf spring  57  results in the application of firm, constant pressure by the leaf spring  57  onto the electrical contact region  700  and in the direction of the object, the electrical communication thereby being constantly maintained. For some embodiments, it may be preferable to provide plastic coating or tape on all or part of leaf spring  57  in order to protect the electrically conductive core material  14  and/or the elastomeric material  16  of the inventive device  100  from one or more sharp edges of the leaf spring  57 . Such coating or tape on leaf spring  57  may also serve to prevent any possible corrosion that may result from interaction of the core  14 &#39;s metal material with the leaf spring  57 &#39;s dissimilar metal material. In inventive embodiments in which structurally discrete elements are combined in the fabrication process, the solder material  71  (which infuses the fabric core  14  material of the electrical contact region  700 ) may serve to both mechanically and electrically connect electrically conductive core  14   a  (at its lower end  13   a   2 ) and electrically conductive core  14   b  (at its lower end  13   b   2 ) to each other, in addition to participating in the electrical connection with respect to the electrically conductive object (stator  54  in  FIG. 6 ; rotor  52  in  FIG. 7 ) that is fixedly joined with inventive device  100 . According to some inventive embodiments, the electric contact region  700  of inventive device  100  is press-fit into a complementary opening provided in the electrically conductive object to which inventive device  100  is fixedly joined. 
   Each sinuous section  30 , in the portion thereof other than the solder-infused portion  70  and the cement-infused portion  80 , represents a laminar material system that includes (i) an electrically conductive core layer  14  of uniform or approximately uniform thickness and (ii) two electrically nonconductive (e.g., elastomeric) exterior layers  16  of varying thicknesses. Each solder-infused portion  70  represents a laminar material system that includes elastomeric layer  16  on the upper side, a portion (e.g., half) of metal plate  90  on the lower side, and core layer  14  sandwiched therebetween. Electrical contact region  700  thus represents an overall laminar material system that combines the two laminar material systems corresponding to the two solder-infused portions  70 , wherein elastomeric material  16  is on the upper side, metal plate  90  is on the lower side, and solder-infused core material  14  is sandwiched therebetween. According to typical inventive practice, the metal plate (e.g., plating)  90  in electrical contact region  700  is at least substantially coextensive with the combined extent of the two end-to-end adjacent solder-infused portions  70 . The elastomeric layers  16  serve not only to protect much of inventive device  100 &#39;s core layers  14  from the elements, but also to enhance the spring-like attributes of inventive device  100 &#39;s spring component  300 . The core layers  14  are strategically covered with a thicker coating of elastomeric material  16  at individual bend locations  17  and joint bend location  19  (between elements  12   a  and  12   b  and directly below interface  23 ), these being locations where the maximum stresses occur when spring element  300  is compressed (and thereby rendered longitudinally shorter) during use of inventive device  100 , such as illustrated in  FIG. 6  and  FIG. 7  in the context of operating machinery  50 . Thickening of elastomeric material  16  at bend locations  17  and  19  can serve not only to structurally reinforce inventive device  100  but also to enhance the resilient quality of spring component  200 . 
   As illustrated in  FIG. 6  and  FIG. 7 , inventive device  100  is incorporated into machinery  50 , which additionally includes an electrically conductive rotor  52  (a rotating part of machinery  50 ) and an electrically conductive stator  54  (a stationary part of machinery  50 ). Inventive device  100 , as shown in  FIG. 6  and  FIG. 7 , is somewhat shorter and squatter than the same inventive device  100  is as shown in  FIG. 1 . Inventive device  100  is shown in  FIG. 6  and  FIG. 7  to be situated between rotor  52  and stator  54  so that the distance along vertical geometric plane v and between interface  59  and the bottom surface of plate  90  of electrical connection region  700  is less than such distance is when inventive device  100  is freely situated as shown in  FIG. 1 . Inventive device  100  is thus caused to be subjected to a longitudinal compressive force or stress that results in a shortening of length L SIN  of spring component  300  and therefore a shortening of the overall length L of inventive device  100 . The bias-exerting attributes of spring component  300  are associated with this compression of spring component  300 . Spring component  300  exerts a bias (force, pressure, influence) with respect to brush component  200  so as to maintain brush component  200 , on a continuous basis, in a moderate pushing or pressing disposition at interface  59  against the slidingly, frictionally contacted object (rotor  52  in  FIG. 6 ; stator  54  in  FIG. 7 ). 
   As shown in  FIG. 6 , inventive device  100  is attached at electrical contact region  700  to stator  54 . In contrast, as shown in  FIG. 7 , inventive device  100  is attached at electrical contact region  700  to rotor  52 . In  FIG. 6  the brush component  200  of stationary inventive device  100  is in sliding contact with rotor  52  at current collection interface  59  during rotation of rotor  52 , whereas in  FIG. 7  the brush component  200  of moving (revolving) inventive device  100  is in sliding contact with stator  54  at current collection interface  59  during rotation of rotor  52 . Inventive device  100  is shown in both  FIG. 6  and  FIG. 7  to be perpendicular to rotor  52 ; otherwise expressed, vertical geometric plane v is shown to be perpendicular to the circular outline of rotor  52 . Nevertheless, brush component  200  can be disposed in either a perpendicular or oblique orientation with respect to rotor  52 , depending on the inventive application. 
     FIG. 6  and  FIG. 7  are highly diagrammatic in nature. The terms “rotor” and “stator” are broadly used herein to refer to any rotating part and any stationary part, respectively, of any of diverse electrical or electromechanical machines (e.g., direct current motor-type machine, direct current generator-type machine, commutator-type machine, etc.) suitable for inventive practice, including but not limited to homopolar motors and homopolar generators. It is to be understood, however, that the rotor-stator arrangements of  FIG. 6  and  FIG. 7  are shown by way of example and are not intended to suggest any limitation regarding the present invention&#39;s potential applicability. For instance, the present invention can be practiced so as to use a solitary inventive device  100  (typically for instrumentation purposes) rather than paired inventive devices  100  (typically for power purposes). According to typical powering modes of inventive practice, the inventive device  100  shown in  FIG. 6  and  FIG. 7  would be one of a pair of inventive devices  100 . The present invention can be practiced in association with any machine having parts that move relative to each other, regardless of whether either part is characterized by rotative motion, linear motion, reciprocating motion, or any other kind of motion. 
   Regardless of whether machinery  50  is in the nature of a motor or a generator or another apparatus, according to typical inventive practice involving powering, inventive devices  100  are used in pairs. In each pair of inventive devices  100 , one inventive device  100  carries electrical current to (or into) the rotor  52 , while the other inventive device  100  carries electrical current from (or out of) the rotor  52 ; depending on the inventive application, either one of the pair of inventive devices  100  can be attached to either the rotor  52  or the stator  54 .  FIG. 6  (which shows inventive device  100  attached to stator  54 ) and  FIG. 7  (which shows inventive device  100  attached to rotor  52 ) can each be conceived as portraying part of machinery  50  either of a motor variety or a generator variety or some other variety. In general, known in the art are various types of machinery (including but not limited to motor and generator types) that implement current collection means. 
   Inventive device  100  represents, in large part, a composite laminate material system characterized by a nonconductive (e.g., elastomeric) exterior layer, viz., elastomeric covering  16 , and an electrically conductive (e.g., metal) interior layer, viz., core  14 . With the exception of electrical contact region  700  (where the elastomeric exterior layer  16  is placed on the inwardly-upwardly facing surface but not the outwardly-downwardly facing surface of each element  12 ), the elastomeric exterior layer  16  is placed on both the inwardly facing surface and the outwardly facing surface of each element  12 . According to some inventive embodiments, each core  14  includes a single sheet  40 , such as shown in  FIG. 8 , of electrically conductive material, either a metal or metal alloy, such as consisting of or including copper, or silver, or gold or another electrically conductive metal. Although the present invention does not require that each core  14  itself have a layered construction, in furtherance of the strength and flexibility of the spring component  300 , many inventive embodiments provide for a plural-layered core  14 , each sub-layer of core  14  being constituted by an individual sheet  40  such as shown in  FIG. 8 . According to typical inventive practice involving plural-layered cores  14 , the adjacent (abutting) sub-layers (sheets)  40  of a plural-layered core  14  are adhered to each other, surface-to-surface, using a cement or other adhesive material. The electrically conductive compositions of the respective sub-layer sheets  40  can be the same or can differ, depending on the inventive embodiment, the electrically conductive material of each sub-layer sheet  40  being either a metal or metal alloy, such as consisting of or including copper, or silver, or gold or another electrically conductive metal. The sheet sub-layers  40  are not necessarily adhered to each other throughout inventive device  100 , over entire expanses of surface-to-surface contact areas between adjacent sheets  40  of inventive device  100 . The amounts, scopes and locations of adhesive material  29  can differ, depending on the inventive embodiment. Generally speaking, the more adhesive  29  used, the greater the stiffness of inventive device  100 . For instance, adhesive material  29  can be used over all or substantially all of the surface-to-surface contact areas, if greater stiffness in inventive device  100  is desired. Alternatively, adhesive material  29  can be applied selectively in certain strategically located portions of the surface-to-surface contact areas (e.g., including at one or more points along junction  23  in brush component  200 ). 
   As illustrated in  FIG. 1  and  FIG. 5  through  FIG. 7 , each core  14  has a plural-layered configuration formed, at least, by two rectangular sheets  40  of electrically conductive material (such as copper or another electrically conductive metal). As discussed hereinabove, adhesive  29  is typically applied, to some extent(s), in order to bond adjacent sheets  40 . Therefore, where adhesive material  29  is present, the plural-layered configuration of core  14  is formed by two adjacent sheets  40  and adhesive material  29  situated between the two sheets  40 . Where adhesive material  29  is absent, the plural-layered configuration of core  14  is formed by two adjacent sheets  40 , touching or nearly touching each other, with no adhesive  29  therebetween. Inventive device  100  is readily envisioned in  FIG. 1  and  FIG. 5  through  FIG. 7  to include or exclude adhesive  29  in any arrangement or pattern. Let us assume, for instance, that adhesive  29  is used throughout or substantially throughout inventive device  100 . Core  14   a  includes two adjoining electrically conductive sheets  40   a   1  and  40   a   2  and adhesive material  29   a  therebetween; core  14   b  includes two adjoining electrically conductive sheets  40   b   1  and  40   b   2  and adhesive material  29   b  therebetween. Brush component  200  describes a laminar material system of four electrically conductive sheet layers  40  and three adhesive material layers  29  in alternation with each other. The four electrically conductive sheet layers  40  (viz.,  40   a   1 ,  40   a   2 ,  40   b   2 ,  40   b   1 ) are separated by the three adhesive layers  29  (viz.,  29   a ,  29   c ,  29   b ). That is, proceeding sequentially downward in  FIG. 5 , the adjacent layers of brush component  200  are  40   a   1 ,  29   a ,  40   a   2 ,  29   c ,  40   b   2 ,  29   b , and  40   b   1 . Layers  40   a   1 ,  29   a , and  40   a   2  are sub-layers of electrically conductive core  14   a ; layers  40   b   1 ,  29   b , and  40   b   2  are sub-layers of electrically conductive core  14   b.    
   Regardless of whether cores  14  are layered (i.e., including at least two sheets  40 ) or unlayered (i.e., including one sheet  40 ), according to frequent inventive practice, each sheet  40  is an electrically conductive fabric member such as a “braided” electrically conductive fabric member, wherein the fabric member&#39;s “braided” configuration of electrically conductive wires lends desirable material qualities in terms of strength and flexibility for purposes of being made part of an integral current collection device  100  in accordance with the present invention. According to typical inventive practice, the electrically conductive wires are made of at least one electrically conductive metal that is selected from the group of electrically conductive metals including, but not limited to, copper, silver, and gold; alternatively, the electrically conductive wires are made of at least one electrically conductive metal alloy that alloys at least one electrically conductive metal that is selected from the group of electrically conductive metals including, but not limited to, copper, silver, and gold. The term “electrically conductive wire fabric” is broadly used herein to refer to any generally planar electrically conductive structure characterized by interlacing, intertwining, interweaving and/or binding of plural (e.g., multiple) electrical wires. An electrically conductive wire fabric can represent any of diverse combinations (e.g., woven, knitted, braided, meshed, knotted, felted and/or bonded) of electrically conductive wires oriented in two and/or three dimensions. The term “electrically conductive wire” is broadly used herein to refer to any elongate electrically conductive member (e.g., made of electrically conductive metal material). An electrically conductive wire can represent a single electrically conductive strand, fiber or filament, or a combination (e.g., bundled, twisted, braided) of electrically conductive strands, fibers or filaments. 
     FIG. 8  is diagrammatically representative of an electrically conductive sheet  40 , one or more of which constitutes a core  14 . In accordance with inventive practice, a sheet  40  need not be fabric. For instance, some inventive embodiments provide for a core  14  comprising at least one electrically conductive metal foil sheet  40 . Nevertheless, according to typical inventive embodiments, each sheet  40  is a piece of fabric, which is characterized by interlacing, intertwining, interweaving and/or binding of electrical wires. For instance, a fabric sheet  40  can exhibit a biaxially braided fabric pattern of wires  41  such as shown in  FIG. 9 , or a triaxially braided fabric pattern of wires  41  such as shown in  FIG. 10 , or a multi-braid pattern of parallelly bonded “braids”  43 . Each braid  43  is a strand, string, cord, etc. that is configured of wires  41  that are braided into such elongate form. 
   Elongate wire braids  43  such as shown in  FIG. 11 , which are akin to the elongate hair braids adopted by some people in their hair style, are commercially available in the form of elongate items known as “solder wicks” (or “desolder wicks”) or “solder braids” (or “desolder braids”). A typical solder wick is manufactured as a metal (e.g., copper) structure coated with a flux such as a rosin material. A fabric sheet  40  can be assembled of individual wire braids  43  from commercial off-the-shelf (COTS) materials. A spindle of (e.g., 0.075 inch) solder wick can be obtained from any of various commercial entities (e.g., Radio Shack™). The solder wick is cut into strips (e.g., 7-inch strips). The solder wick strips are placed in acetone for being cleaned and are then removed from the acetone. The solder wick strips  43  are placed, even, parallel and contiguous, in the slot of a braided fabric fabrication plate (e.g., a 6-inch by 3.5-inch by 0.5-inch thick piece of aluminum having a ¾-inch wide, 1/16-inch deep slot across it for braided fabric assembly), and are secured (e.g., screwed down) at each end of each strip. An adhesive (e.g., Permatex™ automotive gasket cement thinned 50%) is applied to the adjoining solder wicks  43  inside the slot of the braid fabrication plate, and allowed to dry (e.g., about a half hour). The adjoining solder wicks  43  are removed and replaced in an inverted position in the slot of the fabrication plate. The adhesive is again applied to the adjoining solder wicks  43  and allowed to dry in a similar manner, whereupon the completed braided fabric  40  product is removed from the fabrication plate. 
   In the light of the instant disclosure, various methods and techniques for fabricating an inventive device such as shown in  FIG. 1  through  FIG. 7  will be appreciated by the ordinarily skilled artisan. The present invention lends itself to economical fabrication using relatively inexpensive commercial off-the-shelf (COTS) materials, as suitable, such as metal fabrics, solder braids, and silicone rubber from automotive gaskets. With reference to  FIG. 12  through  FIG. 15 , many embodiments for making an inventive device such as inventive device  100  provide initially for the assembly of electrically conductive core  12  material into an electrically conductive core framework  120  that essentially describes the “violin” shape of inventive device  100 .  FIG. 12  and  FIG. 13  illustrate an inventive methodology that takes a bilateral (with respect to vertical geometric plane v), dichotomized approach to fabrication, according to which each of the elements  12   a  and  12   b  is separately formed from one or more sheets  40  (including appropriately bent into sinuous shape), and the elements  12   a  and  12   b  are then joined together to form framework  120 .  FIG. 14  and  FIG. 15  illustrate an alternative, often preferred, inventive methodology that takes a more entire approach to fabrication, according to which one or more sufficiently long wire fabric sheets  400  are bent into a violin shape so as to extend therearound from upper end  13   a   1  to upper end  13   a   2 , thereby integrally forming framework  120 . 
   According to an example of a first inventive approach to making an inventive device, the inventive practitioner provides four planar (unbent) rectangular sheets  40 , practically identical, of electrically conductive wire fabric. The four wire fabric sheets  40  are separated into two pairs, each pair corresponding to an element  12 . For instance, as shown in  FIG. 1  and  FIG. 5 , sheets  40   a   1  and  40   a   2  are paired in element  12   a ; sheets  40   b   1  and  40   b   2  are paired in element  12   b . The two wire fabric sheets  40  in each pair are fixedly adjoined to each other using an adhesive material such as a cement material. According to some inventive embodiments, in addition to or as alternative to adhesive material  29 , cross-stitching is implemented with respect to the two adjoined sheets  40  in each pair in order to strengthen the inventive device and afford it a more stable shape. As depicted in  FIG. 12 , each of the two adjoined pairs of wire fabric sheets  40  is bent together into an element  12  shape, characterized in part by linearity and in part by sinuosity, the two adjoined pairs being bent into practically identical partially linear, partially sinuous shapes. An alternative technique, depicted in  FIG. 13 , is to bend each sheet  40  into an element  12  shape prior to adjoining two sheets  40 , the pairing being performed so as to nestle one bent sheet  40  inside the other; this technique may pose some degree of practical difficulty, however, as it would generally necessitate that the interior bent sheet  40  describe a slightly or moderately smaller element  12  shape than is described by the exterior bent sheet  40 . The two bent, adjoined pairs of wire fabric sheets  40 , each pair representing an element  12 , are coupled in opposition to each other, with the corresponding linear sections  20   a  and  20   b  of the two pairs being fixedly adjoined to each other using an adhesive material such as a cement material, and with the two lower element ends  13   a   2  and  13   b   2  adjoining each other (e.g., touching or nearly touching) end-to-end, thereby forming the violin-shaped electroconductive framework  120 . A lower portion  701  of device  100  (wherein portion  701  encompasses the junction between ends  13   a   2  and  13   b   2 ) is impregnated with the liquid solder material, which solidifies. The solder-infused portion  701  is then heated to re-melt the solder material (which is then allowed to re-solidify), thereby facilitating bonding between wire fabric sheets  40  and between ends  13   a   2  and  13   b   2 . Finally, the re-solidified solder-infused portion  701  is pressed to form a flat contact for attachment to the machinery. 
   According to an example of a second inventive approach to making an inventive device, the inventive practitioner provides two planar (unbent) rectangular sheets  400 , practically identical, of electrically conductive wire fabric. Each sheet  400  is present, in approximately fifty—fifty proportions, in both elements  12   a  and  12   b . For instance, as shown in  FIG. 1  and  FIG. 5 , half of sheet  400 ′ is on the outwardly facing side of element  12   a , and half of sheet  400 ′ is on the outwardly facing side of element  12   b ; half of sheet  400 ″ is on the inwardly facing side of element  12   a , and half of sheet  400 ″ is on the inwardly facing side of element  12   b . The two wire fabric sheets  400  are fixedly adjoined to each other using an adhesive material such as a cement material. According to some inventive embodiments, in addition to or as alternative to adhesive material  29 , cross-stitching is implemented with respect to the two adjoined sheets  400  in order to strengthen the inventive device and afford it a more stable shape. As depicted in  FIG. 14 , the two adjoined wire fabric sheets  400  are bent together into the electrically conductive violin-shaped framework  120 , with the corresponding linear sections  20   a  and  20   b  of the two elements  12   a  and  12   b  being fixedly adjoined to each other using an adhesive material such as a cement material. An alternative technique, depicted in  FIG. 15 , is to bend each sheet  400  into framework  120  violin shape prior to adjoining the two sheets  400 , one bent sheet  400  being nestled inside the other; again, this technique may pose some degree of practical difficulty, as it would generally necessitate that the interior bent sheet  400  describe a slightly or moderately smaller framework  120  shape than is described by the exterior bent sheet  400 . 
   Once the violin-shaped electroconductive framework  120  is provided, the following steps are performed, in no particular order, at suitable locations and to suitable degrees: Inside and outside surfaces of framework  120  are covered with elastomeric material  16 ; two discrete portions of framework  120  are infused with cement material  81  (which is absorbed into the wire fabric  40  or  400  material), thereby forming two discrete cement-infused portions  80 ; an at least substantially continuous portion (extending between the two cement-infused portions  80  and encompassing the adjoining ends of elements  12 ) of framework  120  is infused with solder material  71  (which is absorbed into the wire fabric  40  or  400  material), thereby forming the overall solder-infused portion  701  of the inventive device; the solder-infused portion  701  is heated to re-melt the solder material  71 , which then re-soldifies, such re-melting and re-solidifying of solder material  71  serving to enhance bonding between wire fabric sheets  400  (or between wire fabric sheets  40  as well as between ends  13   a   2  and  13   b   2 ); the re-solidified solder-infused portion  701  is pressed; and, an electrically conductive plating  90  is attached, typically by electroplating, at the underside of the overall solder-infused portion  701  of the inventive device, thereby forming the overall electrical contact area  700  of the inventive device. 
   As described herein in preceding paragraphs with reference to  FIG. 12  through  FIG. 15 , some inventive techniques for making an inventive device  100  involve the assembly of a framework  120  prior to coating with elastomeric material  16 , infiltration with cement material  81 , and infiltration with solder material  71 . However, a variety of these and other inventive fabrication techniques can be practiced. Depending on the method for making an inventive device  100 , each of elastomeric material  16 , cement material  81  and solder material  71  can be applied at practically any stage in the fabrication process. For instance, inside and outside surfaces of individual or adjoined sheets  40  or  400  can be covered with elastomeric material  16 , prior to folding of individual or adjoined sheets  40  or  400 . Similarly, prior to folding of individual or adjoined sheets  40  or  400 , individual or adjoined sheets  40  or  400  can be infused with cement material  81  (which is absorbed into the wire fabric  40  or  400  material) and/or with solder material  71 . Some or all of the elastomeric material  16 , cement material  81  and/or solder material  71  can be applied to each sheet  40  or  400  prior to association with any other sheet  40  or  400 . According to some inventive approaches, elastomer  16  is administered prior to the folding of sheets  40  or  400 ; then, additional elastomer  16  is administered at strategic locations (e.g., at individual bend locations  17  and at joint bend location  19 ) subsequent to the folding of sheets  40  or  400 , or subsequent to the assembly of framework  120 , in order to enhance the “springiness” of the spring component  300  of inventive device  100 . If any elastomer  16 , cement  81  and/or solder  71  is applied prior to folding sheets  40  or  400 , it is important that the inventive practitioner correctly anticipate the locations of such material(s) upon assembly of device  100 . 
   Now referring to  FIG. 16 , inventive braid brush  3000  represents a brush-inclusive, holder-exclusive embodiment of the present invention. Inventive braid brush  3000  corresponds to the brush component  200  of inventive embodiments such as described hereinabove with reference to  FIG. 1  through  FIG. 15 . The inventive prototype of braid brush  3000  pictured in  FIG. 16  was made using COTS solder wicks and automotive gasket silicone rubber. The portrayed brush  3000  includes eight rows of individual solder wick braids  43 , an adhesive solder barrier, and a solder coating on its base. Each row of solder wicks  43  has about nine solder wicks  43  that are discretely arrayed, adjacent and edgewise. The numbers of “rows” and “columms” of solder wicks  43  can be varied in inventive practice in accordance with the desired aspect ratio. 
   Braid brush  3000  can be attached to a holder (e.g., the brush holder disclosed by Lynch et al. at the aforementioned U.S. Pat. No. 6,628,036 B1 issued 30 Sep. 2003, entitled “Electrical Current Transferring and Brush Pressure Exerting Spring Device”) using known soldering techniques for attaching fiber brushes to holders. The combination of a braid brush  3000  with the brush holder of Lynch et al. U.S. Pat. No. 6,628,036 B1 may afford a kind of synergy associated with the commonality of a braid-based construction. Braid brush  3000  may be suitable for any application for which a conventional fiber brush may be suitable, such as involving motors (e.g., homopolar motors), generators (e.g., homopolar generators), commutators, etc. 
   The present invention, which is disclosed herein, is not to be limited by the embodiments described or illustrated herein, which are given by way of example and not of limitation. Other embodiments of the present invention will be apparent to those skilled in the art from a consideration of the instant disclosure or from practice of the present invention. Various omissions, modifications and changes to the principles disclosed herein may be made by one skilled in the art without departing from the true scope and spirit of the present invention, which is indicated by the following claims.