Patent Document

BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention is directed to electric motors, coils for such motors. and methods of preparing wires in such coils, including systems and methods for removing coverings from ends of the wires. 
         [0003]    2. Description of Related Art 
         [0004]    A wide variety of electric motors are known which use coils with a multiplicity of wires. For several reasons, insulation or covering, e.g., enamel, is removed from such wires, e.g., but not limited to, to effect a better contact at conducting ends of the wires. A variety of systems and methods are known for removing material from wires. For example, there are many known systems and methods for mechanically removing wire coverings (using e.g. manual tools and/or stripper machine); removing coverings with chemical solvents; and removing coverings with salts. The following U.S. patents disclose various methods to remove coverings from wires (this listing is illustrative and exemplary and is not meant to be comprehensive or exhaustive): U.S. Pat. Nos. 7,082,856; 6,898,977; 6,799,383; 6,739,217; 6,718,638; 5,832,790; 5,517,755; 5,140,873; 4,367,774; 4,106,377; 4,059,892; 3,962,780; 2,934,982; and 1,831,115. 
         [0005]    A variety of problems are associated with known methods for removing wire coverings. In certain mechanical methods, the wire itself can be damaged or severed. In some cases, too much material is removed, including parts of the wires themselves, resulting in a deficient or ineffective conductor. In certain chemical and salt methods, parts of the wires can be dissolved, chemicals can be spilled, and operators are exposed to the chemicals. Certain common types of Litz wire used in motors is copper with a relatively fine diameter, e.g., 18 gauge wire which is 0.043 inches in diameter (or smaller) with an enamel coating with a thickness of 0.002 inches, which accounts for almost 10% of the wire&#39;s overall thickness. Various known methods for removing the enamel also remove parts of the copper wire itself resulting in uneven current density concentrations and in overheating of joined copper sections. Litz wire, litz-wire cables, and motors with such wires are disclosed, e.g., in U.S. Pat. Nos. 5,517,755; 5,473,211; 4,963,694; 4,631,808; 4,475,053; and 4,412,201. 
         [0006]    The present inventor has recognized the need for efficient and effective systems and methods for removing coverings from wires; for accurately removing only wire coverings without removing parts of the wires themselves; and for removing such coverings in a safe and environmentally friendly manner. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    The present invention discloses, in certain aspects, systems and methods for removing coverings from wire—such as, but not limited to, enamel coverings—using a unique wire coil mounting apparatus for feeding a coil&#39;s ends into a unique blasting apparatus and for manipulating the wire&#39;s ends within the blasting apparatus to facilitate enamel removal. 
         [0008]    The present invention discloses, in certain aspects, methods for removing material from ends of wires, the wires being electrical conductor wires of a coil for an electric motor, the ends of the wires projecting from the coil, the methods, in certain aspects, including: securing a holder apparatus to a coil, the coil having two portions projecting therefrom, each portion including a plurality of wire ends, each wire end having material thereon; positioning the holder apparatus with the coil on a support, the support adjacent a blasting apparatus, the blasting apparatus including an enclosure; moving the holder apparatus with the coil on the support thereby moving the wire ends into the enclosure; and blasting the wire ends within the enclosure to remove the material from the wire ends. 
         [0009]    The present invention discloses, in certain aspects, systems for removing material from ends of wires, the wires being electrical conductor wires of a coil for an electric motor, the ends of the wires projecting from the coil, the systems including: a holder apparatus on a coil, the coil having two portions projecting therefrom, each portion including a plurality of wire ends, each wire end having material thereon; a support, the holder apparatus on the support, the support positionable adjacent a blasting apparatus, the blasting apparatus including an enclosure; and the holder apparatus with the coil movable on the support to thereby move the wire ends into the enclosure. 
         [0010]    Accordingly, the present invention includes features and advantages which are believed to enable it to advance wire covering removal technology. Characteristics and advantages of the present invention described above and additional features and benefits will be readily apparent to those skilled in the art upon consideration of the following detailed description of certain embodiments and referring to the accompanying drawings. 
         [0011]    Certain embodiments of this invention are not limited to any particular individual feature disclosed here, but include combinations of them distinguished from the prior art in their structures, functions, and/or results achieved. Features of the invention have been broadly described so that the detailed descriptions that follow may be better understood, and in order that the contributions of this invention to the arts may be better appreciated. There are, of course, additional aspects of the invention described below and which may be included in the subject matter of the claims to this invention. Those skilled in the art who have the benefit of this invention, its teachings, and suggestions will appreciate that the conceptions of this disclosure may be used as a creative basis for designing other structures, methods and systems for carrying out and practicing the present invention within the scope of the claims herein. The claims of this invention are to be read to include any legally equivalent devices or methods which do not depart from the spirit and scope of the present invention. 
         [0012]    The present invention recognizes and addresses the problems and needs in this area and provides a solution to those problems and a satisfactory meeting of those needs in its various possible embodiments and equivalents thereof. To one of skill in this art who has the benefits of this invention&#39;s realizations, teachings, disclosures, and suggestions, various purposes and advantages will be appreciated from the following description of certain embodiments, given for the purpose of disclosure, when taken in conjunction with the accompanying drawings. The detail in these descriptions is not intended to thwart this patent&#39;s object to claim this invention no matter how others may later attempt to disguise it by variations in form or additions of further improvements. Certain aspects, certain embodiments, and certain preferable features of the invention are set out herein. Any combination of aspects or features shown in any aspect or embodiment can be used except where such aspects or features are mutually exclusive. 
         [0013]    The Abstract that is part hereof is to enable the U.S. Patent and Trademark Office and the public generally, and scientists, engineers, researchers, and practitioners in the art who are not familiar with patent terms or legal terms of phraseology to determine quickly from a cursory inspection or review the nature and general area of the disclosure of this invention. The Abstract is neither intended to define the invention, which is done by the claims, nor is it intended to be limiting of the scope of the invention or of the claims in any way. 
         [0014]    It will be understood that the various embodiments of the present invention may include one, some, or all of the disclosed, described, and/or enumerated features, aspects, improvements and/or technical advantages and/or elements in claims to this invention. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0015]    A more particular description of embodiments of the invention briefly summarized above may be had by references to the embodiments which are shown in the drawings which form a part of this specification. These drawings illustrate certain embodiments and are not to be used to improperly limit the scope of the invention which may have other equally effective or equivalent embodiments. 
           [0016]      FIG. 1A  is a top view of a prior art motor wire coil with coated wire ends. 
           [0017]      FIG. 1B  is an enlarged view of wire ends of the coil of  FIG. 1A . 
           [0018]      FIG. 1C  is a cross-section view of the coil as shown in  FIG. 1A  along line C-C of  FIG. 1B . 
           [0019]      FIG. 2A  is an end view of a coil holder according to the present invention. 
           [0020]      FIG. 2B  is an end view of part of the coil holder of  FIG. 2A . 
           [0021]      FIG. 2C  is an end view of part of the coil holder of  FIG. 2A . 
           [0022]      FIG. 2D  is a perspective view of the part of the coil holder of  FIG. 2B . 
           [0023]      FIG. 2E  is a perspective view of the part of the coil holder of  FIG. 2C . 
           [0024]      FIG. 3A  is a perspective view of a step of a method according to the present invention for securing a coil holder according to the present invention around a coil. 
           [0025]      FIG. 3B  is a perspective view of a step of a method according to the present invention following the step of  FIG. 3A  for securing a coil holder according to the present invention around a coil. 
           [0026]      FIG. 4A  is a front view of a vacuum maintenance structure according to the present invention. 
           [0027]      FIG. 4B  is a rear view of apparatus of  FIG. 4A . 
           [0028]      FIG. 4C  is a front view of the apparatus of  FIG. 4A  with parts separated. 
           [0029]      FIG. 5  is a perspective view of the apparatus of  FIG. 4A  secured to a coil. 
           [0030]      FIG. 6A  is a top perspective view of a coil support system according to the present invention. 
           [0031]      FIG. 6B  is an end view of the coil support system of  FIG. 6A . 
           [0032]      FIG. 6C  is a top view of the coil support system of  FIG. 6A . 
           [0033]      FIG. 6D  is a side view of the coil support system of  FIG. 6A . 
           [0034]      FIG. 7A  is a side view of a blasting system according to the present invention. 
           [0035]      FIG. 7B  is a front view of the system of  FIG. 7A . 
           [0036]      FIG. 7C  is a side view of a blasting system according to the present invention. 
           [0037]      FIG. 7D  is a perspective view of a blasting system according to the present invention. 
           [0038]      FIG. 7E  is a front view of part of a system according to the present invention. 
           [0039]      FIG. 7F  is a front view of part of a system according to the present invention. 
           [0040]      FIG. 8A  is a perspective view illustrating a step of a method according to the present invention for removing a covering from wires of a coil. 
           [0041]      FIG. 8B  is a perspective view of a step of the method of  FIG. 8A  following the step of  FIG. 8A . 
           [0042]      FIG. 8C  is a perspective view of a step of the method of  FIG. 8A  following the step of  FIG. 8B . 
       
    
    
       [0043]    Certain embodiments of the invention are shown in the above-identified figures and described in detail below. Various aspects and features of embodiments of the invention are described below and some are set out in the dependent claims. Any combination of aspects and/or features described below or shown in the dependent claims can be used except where such aspects and/or features are mutually exclusive. It should be understood that the appended drawings and description herein are of certain particular embodiments and are not intended to limit the invention or the appended claims. On the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims. In showing and describing the detailed embodiments, like or identical reference numerals are used to identify common or similar elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness. 
         [0044]    As used herein and throughout all the various portions (and headings) of this patent, the terms “invention”, “present invention” and variations thereof mean one or more embodiment, and are not intended to mean the claimed invention of any particular appended claim(s) or all of the appended claims. Accordingly, the subject or topic of each such reference is not automatically or necessarily part of, or required by, any particular claim(s) merely because of such reference. So long as they are not mutually exclusive or contradictory any aspect or feature or combination of aspects or features of any embodiment disclosed herein may be used in any other embodiment disclosed herein. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0045]    Referring now to  FIG. 1A  (and  FIGS. 1B and 1C ), a prior art coil C with two sides D, for use in an electric motor (e.g. as part of a stator) has a cable B with a multiplicity of enamel-covered wires W (e.g. Litz wire) which are wrapped with insulation I. Ends E of the cable C project from the coil C. In many cases enamel, originally covering the wires W, is removed from the ends E. 
         [0046]      FIG. 2A  shows a coil holder  10  according to the present invention which has two interconnecting pieces  12  ( FIGS. 2B ,  2 D) and  14  ( FIGS. 2C ,  2 E). Projections  12   a ,  12   b  and  12   c  of the piece  12  fit between corresponding pairs of projections  14   a,    14   b  and  14   c  of the piece  14 . Openings  16  are defined between the two pieces  12 ,  14  within which can reside parts (like the sides D,  FIG. 1 ) of a coil. 
         [0047]    The holder  10  may have any peripheral shape (which is circular as viewed in  FIG. 2A ), e.g. but not limited to square, rectangular, triangular, trapezoidal, elliptical, and oval. Optional openings  18 ,  19  define handles  18   a,    19   a,  respectively, for facilitating coil handling, transport, and manipulation. 
         [0048]    The holder pieces  12 ,  14  may be one integral piece or, as shown, may be made of multiple plates  12   p,    14   p , respectively, connected together, e.g. bolted together with bolts through holes  12   t,    14   t,  respectively. 
         [0049]      FIGS. 3A and 3B  illustrate the installation of holders  10  on a coil C. As shown in  FIG. 3A , the piece  14  is positioned with parts D of the coil C passing through the openings  16 . Then, as shown in  FIG. 3B , the projections of the piece  12  are inserted between the corresponding projections of the piece  14  and a bolt  14   s  passing through holes  12   h  and  14   h  is used to bolt the pieces  12 ,  14  together, securing the holder  10  around the coil C allowing limited movement of the coil with respect to the holders. 
         [0050]      FIGS. 4A-4C  illustrate a vacuum maintenance structure, a plate  20 , according to the present invention which has two pieces  22  and  24  which can be taped, glued, and/or fastened together, e.g. with any suitable fastener, e.g., but not limited to, staples, screws, releasable locking material, and/or hook-and-loop fastener material such as VELCRO (Trademark) material (see pieces of hook-and-loop fastener material  22   a ,  24   a,    FIG. 4A ). 
         [0051]    On one side of the structure  20 , (a side which will contact an outer wall of a blasting apparatus around an opening through which a coil can pass), there is, optionally, a piece of material  26  (e.g. cloth, felt material, steel wool, carpet, outdoor carpet, rubber, or gasket material; in one particular aspect, felt material about one-fourth of an inch thick) which facilitates sealing of the structure  20  against the wall. In one aspect, the pieces  22 ,  24  have magnets and/or tape for adhering contact with the enclosure wall. 
         [0052]    Each piece  22 ,  24  has recesses  22 d,  24 d respectively which define openings  28  for receiving side parts of a coil. 
         [0053]      FIG. 5  illustrates the vacuum maintenance structure  20  in place on a coil C held together by tape  20   t.  The coil parts are movable through the openings  28  (e.g. making it possible, once a coil end is within an enclosure, to move the structure  20  on the coil so that the plate  20  and/or piece  26  sealingly contacts an outer wall of the structure). 
         [0054]      FIGS. 6A-6D  illustrate a coil support  30  according to the present invention which has a base  32  with legs  34 . A trolley  40  has rollers  44  rotatably connected to a base  42 . Upwardly projecting edges  36  of the base  32  guide the rollers  44  and the trolley  40 . Optionally, rollers  46  are rotatably mounted on and above the base  42 . As shown in  FIGS. 6A and 6B , the rollers  46  can be sized, configured, and positioned so that holders  10  are rotatably set thereon with some clearance N between the bottoms of the holders  10  and the top of the base  42 . This positioning of the holders  10  facilitates turning and manipulation of a coil on the rollers  46  and positioning and re-positioning of a coil&#39;s wire ends with respect to and within a blasting apparatus&#39;s enclosure. 
         [0055]    The prior art discloses a variety of blasting apparatuses, including but not limited to, those in U.S. Pat. Nos. 7,104,872; 6,712,677; 6,416,390; 6,099,395; 5,685,767; 5,460,564; 5,283,991; 5,216,849; 4,905,426; 4,798,027; 4,753,051; 4,741,130; 4,408,419; 4,339,897; 4,300,318; 4,233,785; 4,019,284; 3,516,205; 3,300,962; 2,584,647; 1,858,475; and 955,714. 
         [0056]      FIGS. 7A and 7B  illustrate a blasting apparatus  50  according to the present invention which has an enclosure  52 ; legs  53 ; a viewing panel  54  (e.g. made of clear glass or plastic); hand insert holes  56  through which an operators hands may pass into the enclosure  52  (hands, optionally, gloved); vacuum system  59  (shown in  FIG. 7B ) for vacuuming cleaning particles and removed material and debris from within the enclosure; and an opening  58  in a wall  57  through which an end of a coil can pass so that its wires&#39; ends can be treated within the enclosure  52 . Optionally, a light fixture  55  is included. 
         [0057]    Optionally, as shown in  FIGS. 7C and 7D  a material or structure may be used to close off the opening  58  while the coil is passing through the opening. This prevents blasting material and material removed from wire ends from exiting the enclosure  52  through the opening  58 . As shown in  FIG. 7C  brush or bristle material or fibers  62  connected to the wall  57  around the periphery of the opening  58  provides a barrier through which a coil is passable, yet which closes off the opening while the coil is present. The brush, fiber or bristle material is flexible so it abuts the coil and conforms to the coil shape substantially closing off the opening  58  with the coil present. A blasting fixture or “gun”  69  (shown in  FIG. 7B ) within the enclosure  52  is used by an operator to direct particles (sand, beads, etc) at the wire ends to remove wire coverings, e.g. enamel. 
         [0058]    Optionally, as shown in  FIG. 7D , a plurality of independent flaps  64  of flexible material are positioned in the opening  58  and a coil is passed between them, as they flex, into the enclosure  52 . 
         [0059]      FIGS. 7E and 7F  show other embodiments with multiple flaps. In  FIG. 7E , four flaps  66  are used. In  FIG. 7F , two flaps  68 ,  69  are used with the flap  69  having two openings  69   a  to accommodate parts of a coil with a coil end projecting into the enclosure  52 . 
         [0060]      FIGS. 8A-8C  illustrate steps in a method according to the present invention. As shown in  FIG. 8A , a coil C with ends E is secured to holders  10  which are resting on rollers  46  of a trolley  40 . The trolley  40  is on a support  30  adjacent a blasting apparatus  50 . The coil C is positioned so that its ends can be moved through the opening  58  into the enclosure  52  of the apparatus  50 . A vacuum maintenance structure  20  can be movably connected to the coil C or applied once the ends E are in the enclosure  52 . 
         [0061]    As shown in  FIG. 8B , the coil ends E have been moved within the enclosure  52  by moving the trolley  40  and, if needed, by moving the coil C (to the right as shown in  FIG. 8B ) into the enclosure  52 . The structure  20  is placed sealingly against the wall  57  around the opening  58  (see  FIG. 8C ). Blasting of the coil ends E with material removing particles commences. 
         [0062]    The coil C and thus its ends E within the enclosure  52  can be rotated by rotating the holders  10  on the rollers  46  to facilitate enamel removal from all surfaces of the wire ends E (or ends are movable by repositioing holders with flat surfaces on the rollers  46 ). The wire ends can be rotated through a full  360  degrees, with the holders  10  rotating on the rollers  46 . 
         [0063]    The present invention, therefore, provides in some, but not in necessarily all, embodiments a method to remove material from ends of wires which are electrical conductor wires of a coil for an electric motor, the ends of the wires projecting from the coil, the method including: securing a holder apparatus to a coil having two portions projecting therefrom, each portion including a plurality of wire ends, the ends having material thereon; positioning the holder apparatus with the coil on a support adjacent a blasting apparatus that includes an enclosure; moving the holder apparatus with the coil on the support thereby moving the wire ends into the enclosure; and blasting the wire ends to remove the material from the wire ends. Such a method according to the present invention may include one, or some, in any possible combination of the following: wherein the coil has two spaced-apart sides, and the holder apparatus is at least one holder, the at least one holder having two openings, one each of the two openings for receiving part of a side of the coil, the method further including emplacing part of each side in one of the two openings; wherein the at least one holder apparatus is two matable parts combinable about the sides of the coil, the method further including combining the two matable parts about the coil so a part of each side of the coil is in one of the two openings; wherein the two matable parts include a first part with projections and a second part with recesses, the method further including combining the two matable parts with each projection of the first part in a recess of the second part; wherein the at least one holder has at least one cut out portion for facilitating handling of the holder; wherein the at least one holder is two spaced-apart holders; wherein the holder apparatus is generally round to facilitate rotation of the coil with respect to the support to rotate the coil ends within the enclosure; wherein the support is a wheeled trolley positioned on a base, the base adjacent the enclosure of the blasting apparatus, the method further including moving the wire ends into the enclosure by moving the wheeled trolley on the base; wherein the wheeled trolley has a plurality of spaced-apart rollers rotatably mounted thereon, the holder apparatus movably positioned on the plurality of rollers, the method further including moving the wire ends within the enclosure to facilitate removal of material therefrom by moving the holder apparatus on rollers of the plurality of rollers; wherein the holder apparatus is two spaced-apart holders, the method further including moving each holder on two spaced-apart rollers of the plurality of rollers; wherein the enclosure has a coil opening through which part of the coil is movable to move the wire ends into the enclosure, the method further including placing a seal structure at the coil opening and around the coil to seal off the coil opening while part of the coil is passing through the coil opening to facilitate the blasting of material off the wire ends; and/or wherein the seal structure is seal apparatus connected to the enclosure or it is two seal pieces emplaceable on the coil, at least one of the two seal pieces having openings for accommodating parts of sides of the coil, the method further including emplacing the two seal pieces on the coil, and connecting the two seal pieces together. 
         [0064]    The present invention, therefore, provides in some, but not in necessarily all, embodiments a method to remove material from ends of wires, the wires comprising electrical conductor wires of a coil for an electric motor, the ends of the wires projecting from the coil, the method including: securing a holder apparatus to a coil, the coil having two portions projecting therefrom, each portion including a plurality of wire ends, each wire end having material thereon; positioning the holder apparatus with the coil on a support, the support adjacent a blasting apparatus, the blasting apparatus including an enclosure; moving the holder apparatus with the coil on the support thereby moving the wire ends into the enclosure; and blasting the wire ends within the enclosure to remove the material from the wire ends; wherein the coil has two spaced-apart sides, and the holder apparatus comprises two holders, each holder having two openings, one each of the two openings for receiving part of a side of the coil, the method further including emplacing part of each side in one of the two openings; wherein each holder comprises two matable parts combinable about the sides of the coil, the method further including combining the two matable parts about the coil so a part of each side of the coil is in one of the two openings; wherein each holder is generally round; wherein the support comprises a wheeled trolley positioned on a base, the base adjacent the enclosure of the blasting apparatus, the method further including moving the wire ends into the enclosure by moving the wheeled trolley on the base. 
         [0065]    The present invention, therefore, provides in some, but not in necessarily all, embodiments a system for removing material from ends of wires, the wires being electrical conductor wires of a coil for an electric motor, the ends of the wires projecting from the coil, the system including: a holder apparatus for securement to a coil, the coil having two portions projecting therefrom, each portion including a plurality of wire ends, each wire end having material thereon; a support, the holder apparatus on the support, the support positionable adjacent a blasting apparatus, the blasting apparatus including an enclosure; and the holder apparatus with the coil movable on the support to thereby move the wire ends into the enclosure. Such a system according to the present invention may include one, or some, in any possible combination of the following: wherein the coil has two spaced-apart sides, and the holder apparatus is at least one holder, the at least one holder having two openings, one each of the two openings for receiving part of a side of the coil; wherein the at least one holder apparatus is two matable parts combinable about the sides of the coil so a part of each side of the coil is in one of the two openings, the two matable parts including a first part with projections and a second part with recesses, each projection of the first part receivable in a recess of the second part; wherein the support is a wheeled trolley positioned on a base, the base positionable adjacent the enclosure of the blasting apparatus, the wheeled trolley movable on the base to move the wire ends into the enclosure; wherein the wheeled trolley has a plurality of spaced-apart rollers rotatably mounted thereon, the holder apparatus movably positioned on the plurality of rollers so that moving the holder apparatus on rollers of the plurality of rollers moves the wire ends within the enclosure to facilitate removal of material therefrom; and/or wherein the enclosure has a coil opening through which part of the coil is movable to move the wire ends into the enclosure, the system further including a seal structure positionable at the coil opening and around the coil to seal off the coil opening while part of the coil is passing through the coil opening to facilitate the blasting of material off the wire ends; wherein the seal structure is one of seal apparatus connected to the enclosure and two seal pieces emplaceable on the coil, at least one of the two seal pieces having openings for accommodating parts of sides of the coil. 
         [0066]    In conclusion, therefore, it is seen that the present invention and the embodiments disclosed herein and those covered by the appended claims are well adapted to carry out the objectives and obtain the ends set forth. Certain changes can be made in the subject matter without departing from the spirit and the scope of this invention. It is realized that changes are possible within the scope of this invention and it is further intended that each element or step recited in any of the following claims is to be understood as referring to the step literally and/or to all equivalent elements or steps. The following claims are intended to cover the invention as broadly as legally possible in whatever form it may be utilized. The invention claimed herein is new and novel in accordance with 35 U.S.C. §102 and satisfies the conditions for patentability in §102. The invention claimed herein is not obvious in accordance with 35 U.S.C. §103 and satisfies the conditions for patentability in §103. This specification and the claims that follow are in accordance with all of the requirements of 35 U.S.C. §112. The inventor may rely on the Doctrine of Equivalents to determine and assess the scope of the invention and of the claims that follow as they may pertain to apparatus not materially departing from, but outside of, the literal scope of the invention as set forth in the following claims. All patents and applications identified herein are incorporated fully herein for all purposes. It is the express intention of the applicant not to invoke 35 U.S.C. §112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function. In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements.

Technology Category: 7