Patent Publication Number: US-7586057-B2

Title: Electrical switching apparatus and vented case therefor

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is related to commonly assigned, concurrently filed: U.S. patent application Ser. No. 11/560,423,filed Nov.16, 2006, entitled “ELECTRICAL SWITCHING APPARATUS, AND CASE AND TERMINAL SHIELD THEREFOR”. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates generally to electrical switching apparatus and, more particularly, to vented cases for electrical switching apparatus. 
   2. Background Information 
   Electrical equipment such as, for example, relays, circuit breakers, electric meters and transformers, are typically housed within an electrical enclosure such as, for example, a housing such as a cabinet. 
   Panelboards or load centers, for example, are types of electrical enclosures which serve to distribute power for residential or commercial applications. Typically, the panelboard or load center includes a housing enclosing a plurality of electrical switching apparatus (e.g., without limitation, circuit breakers) for protecting branch circuits against electrical faults or overload conditions. It is desirable to maximize the efficiency with which the available space within the housing is used. Accordingly, the circuit breakers are often disposed, for example, adjacent one another in parallel rows with one or more bus bars extending between the rows. The circuit breakers may also be removably coupled to a DIN rail. DIN is short for Deutsches Insitut für Normung eV, which is a German standard-setting organization. Accordingly, a DIN rail is a connecting rail structure which is designed to satisfy DIN standards. Some manufacturers of circuit breakers provide the circuit breaker with a DIN rail mounting structure, such as an integrally molded recess sized to provide snap-on attachment to the DIN rail. 
     FIG. 1  shows an example of three such circuit breakers  2 , which are ganged (e.g., coupled) together side-by-side. Each circuit breaker  2  is essentially identical, including a case  6  with a first half  8  and a second half  10 . Handles  12  protrude from the top (from the perspective of  FIG. 1 ) of the cases  6  and, in the example of  FIG. 1 , are ganged (e.g., coupled) together. The end  4  of each circuit breaker  2  includes a terminal  14 , with protrusions  16 , 18  being disposed on opposite sides of the terminals  14 . A single vent  20  provides the sole means for ventilating ionized gases from within each circuit breaker  2 . The interior of the second half  10  of one of the circuit breakers  2 , and the terminal  14 , protrusion  18  and vent  20  thereof are shown in  FIG. 2 , which also shows the aforementioned molded DIN rail mounting structure  22 . 
   Such circuit breakers  2  are subject to industry safety regulations. For example and without limitation, the Underwriter&#39;s Laboratory (UL) establishes regulations pertaining to the specifications of circuit breaker arc chutes (not shown) and, in particular, the venting capability of circuit breakers to sufficiently vent ionized gases which are produced as a byproduct of an arc generated when the circuit breaker trips. Such regulations are becoming increasingly stringent. As a result, many existing circuit breakers such as, for example, the circuit breaker  2  with single vent  20  discussed hereinabove with respect to  FIGS. 1 and 2 , do not satisfy such regulations for use in certain applications (e.g., without limitation, branch circuit protection). It is, therefore, difficult to simultaneously satisfy both the established industry safety regulations and the design objective of minimizing the overall size of the circuit breakers, and thus the overall space required for the panelboard or load center. 
   There is, therefore, room for improvement in electrical switching apparatus and in cases therefor. 
   SUMMARY OF THE INVENTION 
   These needs and others are met by embodiments of the invention, which are directed to a vented case for electrical switching apparatus such as, for example, circuit breakers. 
   As one aspect of the invention, a vented case is provided for an electrical switching apparatus. The electrical switching apparatus includes an arc chute structured to attract and dissipate an arc. The arc produces an ionized gas. The vented case comprises: at least one housing member comprising an interior, an exterior, a first end, a second end disposed generally opposite and distal from the first end, and an intermediate portion extending between the first end and the second end; and at least one vent structured to discharge the ionized gas from the interior of such housing member to the exterior of such housing member. Such vent includes a plurality of venting passages, each being structured to extend from proximate the arc chute within the interior to the exterior. 
   Such vent may be disposed proximate at least one of the first end and the second end of such housing member. Such vent may comprise a primary vent disposed at or about the first end of such housing member of the vented case, wherein the primary vent comprises at least a first venting passage and a second venting passage spaced from but proximate to the first venting passage. A portion of the first venting passage of the primary vent may combine with a portion of the second venting passage of the primary vent, thereby forming a common venting passage. The common venting passage may be structured to be disposed proximate the arc chute of the electrical switching apparatus. The primary vent may further comprise a third venting passage, wherein the third venting passage interconnects the first venting passage with the second venting passage. The third venting passage may be substantially perpendicular with respect to the first and second venting passages. The primary vent may be generally capital I-shaped. 
   The first end of such housing member of the vented case may comprise a first terminal, and the second end of such housing member may comprise a second terminal. Such vent may further comprise at least one secondary vent disposed at or about at least one of the first terminal and the second terminal, wherein the venting passages of such vent further comprise at least one secondary venting passage. Such secondary venting passage may extend from the intermediate portion of such housing member of the vented case to the secondary vent. Such secondary vent may comprise a first vent aperture disposed at or about the first terminal and a second vent aperture disposed at or about the second terminal, and such secondary venting passage may comprise a first secondary venting passage extending from the intermediate portion of such housing member of the vented case to the first vent aperture, and a second secondary venting passage extending from the intermediate portion of such housing member of the vented case to the second vent aperture. 
   Such housing member may further comprise a plurality of protrusions extending substantially perpendicularly outwardly from the interior thereof. The protrusions may define a first substantially vertical wall disposed proximate the first terminal of the first end of such housing member and a second substantially vertical wall disposed proximate the second terminal of the second end of such housing member, wherein the first vent aperture comprises an aperture through the first substantially vertical wall and the second vent aperture comprises an aperture through the second substantially vertical wall. 
   The vented case may comprise a first molded housing member and a second molded housing member coupled to and disposed opposite from the first housing member. The first molded housing member of the vented case may include a plurality of first protrusions extending outwardly from the first molded housing member toward the second molded housing member, and a plurality of first recesses, and the second molded housing member of the vented case may include a plurality of second protrusions extending outwardly from the second molded housing member toward the first molded housing member, and a plurality of second recesses. Each of the first recesses of the first molded housing member may align with a corresponding one of the second recesses of the second molded housing member, in order to form such vent, and each of the first protrusions of the first molded housing member may align with a corresponding one of the second protrusions of the second molded housing member, in order to form the venting passages. 
   As another aspect of the invention, an electrical switching apparatus comprises: separable contacts; an arc chute disposed proximate the separable contacts, the arc chute being structured to attract and dissipate an arc from the separable contacts, the arc producing an ionized gas; and a vented case housing the separable contacts and the arc chute, the vented case comprising: at least one housing member comprising an interior, an exterior, a first end, a second end disposed generally opposite and distal from the first end, and an intermediate portion extending between the first end and the second end, and at least one vent structured to discharge the ionized gas from the interior of such housing member to the exterior of such housing member. Such vent includes a plurality of venting passages, each of the venting passages extending from proximate the arc chute within the interior to the exterior of the at least one housing member of the vented case. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which: 
       FIG. 1  is an end elevation view of three circuit breakers which are ganged together side-by-side; 
       FIG. 2  is an isometric view of the interior of one half of the case of one of the circuit breakers of  FIG. 1 ; 
       FIG. 3  is an isometric view of the interior of one half of a circuit breaker case and terminal shield therefor, in accordance with an embodiment of the invention; 
       FIG. 4  is a side elevation view of the other half of the circuit breaker case and terminal shield therefor of  FIG. 3 , also showing internal structures of the circuit breaker; and 
       FIG. 5  is an end elevation view of three circuit breakers which are ganged together side-by-side, with each of the circuit breakers employing a terminal shield in accordance with an embodiment of the invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   For purposes of illustration, embodiments of the invention will be described as applied to three molded case circuit breakers which are ganged together side-by-side, although it will become apparent that they could also be applied to a wide variety of electrical switching apparatus (e.g., without limitation, circuit switching devices and other circuit interrupters, such as contactors, motor starters, motor controllers and other load controllers) having an arc chute, which are arranged in any suitable number and/or configuration. 
   Directional phrases used herein, such as, for example, left, right, top, bottom, upper, lower, front, back and derivatives thereof, relate to the orientation of the elements shown in the drawings and are not limiting upon the claims unless expressly recited therein. 
   As employed herein, the term “ionized” means completely or partially converted into ions, or ions and electrons, and being at least somewhat electrically conductive such as, for example, ionized gases generated by arcing between separable electrical contacts of a circuit breaker when opened. 
   As employed herein, the terms “case” or “casing” and derivatives thereof refer to any known or suitable enclosure or housing structured to contain the internal components (e.g., without limitation, operating mechanism; separable contacts; arc chute) of an electrical switching apparatus such as, for example and without limitation, a circuit breaker. 
   As employed herein, the term “vented” refers to the nature of the disclosed case for electrical switching apparatus, wherein the case has a number of vents or other known or suitable structures which enable the electrical switching apparatus to expel or otherwise suitably release or discharge undesirable gas (e.g., ionized gas) and/or matter from within the case to the exterior thereof. 
   As employed herein, the term “vent” refers to any known or suitable mechanism, opening and/or passage which functions, for example, to expel or otherwise suitably release or discharge undesirable gas (e.g., ionized gas) and/or matter from within the case of an electrical switching apparatus to the exterior thereof. 
   As employed herein, the statement that two or more parts are “coupled” together shall mean that the parts are joined together either directly or joined through one or more intermediate parts. 
   As employed herein, the term “number” shall mean one or an integer greater than one (i.e., a plurality). 
     FIGS. 3 and 4  show portions of a case  100  for an electrical switching apparatus, such as a circuit breaker  30 . The case  100  is vented in accordance with an embodiment of the invention. The circuit breaker  30  generally includes an arc chute  32  and separable contacts, such as the stationary contact  38  and movable contact  40 , shown in  FIG. 4 . The arc chute  32  is housed by the vented case  100 , and is disposed proximate the separable contacts  38 , 40  therein. The arc chute  32  is, therefore, structured to attract and dissipate an arc  34  (shown in simplified form in  FIG. 4 ) from the separable contacts  38 , 40 . The arc  34  is generated when the separable contacts  38 , 40  separate, for example, after the circuit breaker  30  trips. Ionized gas, which is indicated generally by arrows  36  in  FIG. 4 , is produced as a by-product of the arc  34 . Such ionized gas  36  can be damaging to the internal components (e.g., without limitation, arc chute  32 ; separable contacts  38 , 40 ) of the circuit breaker  30 . For example, ionized gas  36  can facilitate additional, undesired arcs (not shown). Accordingly, it is strongly desirable to rapidly vent such ionized gas  36  from the circuit breaker  30 . Additionally, circuit breakers (e.g.,  30 ) which are employed, for example and without limitation, to provide branch circuit protection, are subject to stringent industry regulations. One such regulation, which is generally well known, is Underwriter&#39;s Laboratory (UL)  489  which governs certain standards for branch circuit breakers. Among other benefits, the disclosed circuit breaker  30  and structures thereof, including the vented case  100  and the terminal shields  200 , 200 ′ which will be discussed hereinbelow, meet or exceed the requirements of UL  489 . 
   The vented case  100  in the example shown and described herein, includes at least one housing member  102  ( FIGS. 4 and 5 ),  104  ( FIGS. 3 and 5 ) having an interior  106  ( FIGS. 4 and 5 ) and  108  ( FIGS. 3 and 5 ), an exterior  110  ( FIGS. 4 and 5 ) and  112  ( FIGS. 3 and 5 ), a first end  114 , a second end  116  ( FIGS. 3 and 4 ) disposed generally opposite and distal from the first end  114 , and an intermediate portion  118  ( FIGS. 3 and 4 ) between the first and second ends  114 , 116 . The example vented case  100  comprises a first housing member  102 , shown in  FIGS. 4 and 5 , and a second housing member  104 , shown in  FIGS. 3 and 5 , which is coupled to and disposed opposite from the first housing member  102 , as shown in  FIG. 5  ( FIG. 5  shows three such vented cases  100 , one for each of three adjacent circuit breakers  30  which are ganged together, side-by-side, and which are all substantially identical). 
   The vented case  100  further includes at least one vent  120 , 122 , 124  structured to discharge the ionized gas  36  ( FIG. 4 ) from the interior  106  ( FIGS. 4 and 5 ) and  108  ( FIGS. 3 and 5 ) of the housing members  102  ( FIGS. 4 and 5 ) and  104  ( FIGS. 3 and 5 ) to the exterior  110  ( FIGS. 4 and 5 ) and  112  ( FIGS. 3 and 5 ). As will be discussed, each vent  120 , 122 , 124  includes a plurality of venting passages  126 , 128 , 130  (best shown in FIG.  5 ), 132 , 134 , 136  structured to extend from proximate the arc chute  32  ( FIG. 4 ) within the case  100 , to the exterior of the circuit breaker  30  ( FIGS. 4 and 5 ). The example vented case  100  includes a primary vent  120 , which is disposed at or about the first end  114  of the vented case  100 . For simplicity of disclosure and ease of illustration, only one of the vented cases  100  (the left most case  100  from the perspective of  FIG. 5 ) will be described in detail. It will however, be appreciated that the other two circuit breakers  30  and vented cases  100  therefor, are substantially identical. 
   Specifically, the primary vent  120  includes at least a first venting passage  126 , and a second venting passage  128  which is spaced from but proximate to the first venting passage  126 . The first venting passage  126  of the example primary vent  120  combines with a portion of the second venting passage  128  to form a common venting passage  132 , as shown in  FIGS. 3 and 4 . The common venting passage  132  is disposed proximate the arc chute  32  of the circuit breaker  30 , as shown in  FIG. 4 . In this manner, the cross-sectional area and overall volume available for discharging the ionized gas  36  ( FIG. 4 ) from the arc chute  32  ( FIG. 4 ) out of the primary vent  120 , is greatly increased in comparison with known circuit breaker vents such as, for example, vent  20  and the relatively narrow serpentine single venting passage thereof of  FIG. 2 , previously discussed. Accordingly, the primary vent  120  of the disclosed vented case  100  greatly improves the venting efficiency of the circuit breaker  30 . 
   The venting efficiency of the disclosed circuit breaker  30  is still further improved through the inclusion of several other additional unique features. Among them is a third venting passage  130  (best shown in  FIG. 5 ) of the vented case  100  which interconnects the first and second venting passages  126 , 128  of the primary vent  120  and, in the example shown and described herein, is also substantially perpendicular with respect to such passages  126 , 128 . Accordingly, it will be appreciated that the exemplary primary vent  120  is generally shaped like a capital letter “I”, when the vented case  100  is viewed from the end elevation perspective of  FIG. 5 . It will also be appreciated that the three venting passages  126 , 128 , 130  of the I-shaped primary vent  120  provide a substantially increased cross-sectional venting area as compared, for example, to the single relatively narrow, rectangular-shaped vent  20  of  FIG. 1 , previously discussed. It will, however, be appreciated that the primary vent  120  could have any known or suitable alternative shape (not shown) and/or count of venting passages (not shown) other than the example “I” shape and/or three venting passages  126 , 128 , 130 , which are shown, without departing from the scope of the invention. 
   In addition to the aforementioned primary vent  120 , the example vented case  100  further includes at least one secondary vent  122 , 124  (only one secondary vent  122  is shown in  FIG. 5 ). Specifically, the first end  114  of the vented case  100 , includes a first terminal  138  and a first terminal opening  142  therefor, and the second end  116  ( FIGS. 3 and 4 ) of the vented case  100  includes a second terminal  140  ( FIG. 4 ) and a second terminal opening  144  ( FIGS. 3 and 4 ) therefor. The example vented case  100  includes a first secondary vent  122  in the form of a first vent aperture disposed at or about the first terminal  138 , and a second secondary vent  124  ( FIGS. 3 and 4 ) in the form of a second vent aperture disposed at or about the second terminal  140  ( FIG. 4 ). It will be appreciated with reference to the dashed lines of  FIG. 4 , which represent the aforementioned ionized gas  36 , that a first secondary venting passage  134  extends from the intermediate portion  118  of the housing member  102  to the first secondary vent  122 , and a secondary venting passage  136  extends from the intermediate portion  118  to the second secondary vent  124 . 
   In other words, the aforementioned venting passages (e.g.,  126 , 128 , 130 , 132 , 134 , 136 ) of the vents (e.g.,  120 , 122 , 124 ), are formed by the alignment of a plurality of first protrusions  150  which extend outwardly from the interior  106  of the first housing member  102 , as shown in  FIG. 4 , and align with a corresponding plurality of second protrusions  154  which extend outwardly from the interior  108  of the second housing member  104 , as shown in  FIG. 3 . Specifically, the venting passages (e.g.,  126 , 128 , 130 , 132 , 134 , 136 ) are formed by the passages extending between the aligned first and second protrusions  150 , 154 . Similarly, the vents (e.g.,  120 , 122 , 124 ) are formed by the apertures or thru holes created by the alignment of corresponding first and second recesses  152 , 156  of the first and second housing members  102 , 104  (see, for example, vent  122  in  FIG. 5 ). Accordingly, it will be appreciated that the exemplary first and second housing members  102 , 104  are contemplated as comprising molded housing members, wherein the aforementioned protrusions  150 , 154  and recesses  152 , 156  are molded portions of the interiors  106 , 108  of the molded housing members  102 , 104 . It will also be appreciated that the molded housing members  102 , 104  may be made from any known or suitable electrically insulative material such as, for example and without limitation, plastic, and that they preferably each comprise one single piece of material. 
   As shown in  FIGS. 3 and 4 , the example protrusions  150  ( FIG. 4 ),  154  ( FIG. 3 ) form a number of substantially vertical walls, such as the first and second substantially vertical walls  146 , 148 , shown, which are disposed proximate the first terminal  138  of the first end  114  of vented case  100  and the second terminal  140  of the second end  116  of vented case  100 , respectively. The example first and second secondary vents  122 , 124  comprise respective apertures through the first and second substantially vertical walls  146 , 148 , as shown. 
   The disclosed circuit breaker  30  also includes at least one terminal shield  200 , 200 ′ (terminal shield  200 ′ is partially shown, only in  FIGS. 3 and 4 ) which, among other benefits, provides improved through air and over surface spacing between the terminals (e.g., first and second terminals  138  ( FIGS. 4 and 5 ),  140  ( FIG. 4 )) of the circuit breaker  30 . Thus, the disclosed circuit breaker  30  provides improved resistance, for example, to undesired arcing between adjacent circuit breaker terminals (e.g., without limitation, adjacent terminals  138  of adjacent circuit breakers  30  of  FIG. 5 ), in comparison with known prior art circuit breaker terminal designs (see, for example, relatively narrow and tapered protrusions  16 , 18  of terminals  14  of circuit breaker  2  of  FIG. 1 ). Like the aforementioned vented case  100 , such terminal shields  200 , 200 ′ also meet or exceed well established industry safety regulations such as, for example and without limitation, Underwriter&#39;s Laboratory (UL)  489 . 
   For simplicity of disclosure only one of the terminal shields  200  for one of the circuit breakers  30  of  FIG. 5  will be described in detail. It will, however, be appreciated that the other breakers  30  and terminal shields  200 ′ therefor, are substantially identical. As shown in  FIG. 5 , each terminal shield  200  includes at least one pair of protrusions  202  structured to extend outwardly (best shown in  FIGS. 3 and 4 ) from the circuit breaker case  100  on opposing sides of a corresponding one of the terminal openings  142 . Each of the protrusions  202  has an interior surface  206 , which faces a corresponding terminal  138  (see also interior surface  208  of protrusions  204  facing corresponding terminal  140  in  FIGS. 3 and 4 ), and an exterior surface  210  disposed opposite the interior surface  206  (see also, for example, exterior surface  212  opposite interior surface  208  of protrusion  204  in  FIG. 3 ). The exterior surface  210  of each protrusion  202  aligns with the first side  110 , 112  of a corresponding one of the first and second housing members  102 , 104 . The interior surface  206  of each protrusion  202  is disposed proximate a corresponding one of the terminal openings  142  of the circuit breaker case  100 , and preferably abuts the terminal opening  142 , as shown. Accordingly, the example protrusions  202  extend between the terminal opening  142  and the corresponding exterior side  110 , 112  of the corresponding housing member  102 , 104 . It will, therefore, be appreciated that the terminal shield  200  is substantially wider than known prior art structures (e.g., first and second protrusions  16 , 18  of  FIG. 1 ) for shielding terminals (e.g., terminal  14  of  FIG. 1 ). More specifically, as shown in  FIG. 5 , each circuit breaker  30  has a first width  158 , and each of the protrusions  202  of terminal shield  200  has a second width  238 . In the example shown, the combined second width  238  of the protrusions  202  is preferably at least about 40 percent of the first width  158  of the circuit breaker case  100 . 
   Additionally, unlike the tapered first and second protrusion  16 , 18  shown and described with respect to  FIG. 1 , the interior and exterior surfaces  206 , 210  of the protrusions  202  of the example terminal shield  200  are substantially parallel with respect to one another, and extend substantially perpendicularly outwardly from the first end  114  of the case  100 . It will be appreciated that the configuration of each protrusion  204  of the second terminal shield  200 ′, partially shown in  FIGS. 3 and 4 , extends outwardly from the second end  116  of the circuit breaker case  100  and is substantially identical to the first protrusions  202  of the first terminal shield  200 . However, it will also be appreciated that any suitable count and configuration of terminal shields (e.g.,  200 , 200 ′) and protrusions (e.g.,  202 , 204 ) therefor, could be employed without departing from the scope of the invention. 
   As best shown in  FIGS. 3 and 4 , each protrusion  202 , 204  further includes a first end  214 , 216 , a second end  218 , 220 , a first side  222 , 224  and a second side  226 , 228 . The first end  214 , 216  of each protrusion  202 , 204  is coupled to a corresponding one of the first and second ends  114 , 116  of the circuit breaker case  100 , as shown. The second end  218 , 220  of each protrusion  202 , 204  is disposed opposite and distal from the first end  214 , 216 . The first side  222 , 224  of each protrusion  202 , 204  extends beyond a corresponding one of the first and second terminal openings  142 , 144  on one side thereof, and the second side  226 , 228  of each protrusion  202 , 204  extends beyond the corresponding terminal opening  142 , 144  on the other side thereof. In this manner, the terminals  138 , 140  are substantially electrically isolated, for example and without limitation, with respect to adjacent terminals (see, for example, adjacent terminals  142  of adjacent circuit breakers  30  of  FIG. 5 ). The terminal shields  200 , 200 ′ simultaneously, advantageously do not undesirably interfere (e.g., block; restrict) access to the terminals  138 , 140 . 
   As previously discussed, the first and second housing members  102  ( FIGS. 4 and 5 ) and  104  ( FIGS. 3 and 5 ) of the circuit breaker case  100  preferably comprise first and second molded housing members made from a single piece of any known or suitable electrically insulative material (e.g., without limitation, plastic). Accordingly, it will be appreciated that the protrusions  202  ( FIGS. 3-5 ) and  204  ( FIGS. 3 and 4 ) of the example terminal shields  200  ( FIGS. 3-5 ) and  200 ′ ( FIGS. 3 and 4 ) are contemplated as comprising first integral extensions  230  ( FIGS. 4 and 5 ) and  232  ( FIGS. 3 and 5 ) extending outwardly from the first ends of the single piece molded members  102  ( FIGS. 4 and 5 ) and  104  ( FIGS. 3 and 5 ), and second integral extensions  234  ( FIG. 4) and 236  ( FIG. 3 ), which extend from the second ends of the single piece molded members  102  ( FIG. 4) and 104  ( FIG. 3 ). It will be appreciated, however, that the terminal shields  200 , 200 ′ could, for example and without limitation, comprise separate components (not shown) which are separately made and subsequently coupled to the housing members  102 , 104 . 
   Accordingly, the disclosed circuit breaker  30  provides a vented case  100  having an optimized number and configuration of vents (e.g.,  120 , 122 , 124 ) and venting passages (e.g.,  126 , 128 , 130 , 132 , 134 , 136 ), thereby improving the efficiency with which the circuit breaker  30  vents ionized gas  36 . Terminal shields (e.g.,  200 , 200 ′) are also provided which, among other benefits, resist undesirable arcing and electrical shorts associated therewith. 
   While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.