Abstract:
A switch enclosure apparatus and method are disclosed. An enclosure can be provided, wherein the enclosure comprises a plurality of walls from which a cavity can be formed. A plunger or other actuating mechanism can also be provided comprising one or more key portions, wherein said plunger is partially located and maintained within said cavity of said enclosure. Additionally, one or more slots can be formed from one or more walls, (e.g., side walls, top wall, bottom wall, etc.) of said enclosure for engaging said one or more of the key portions of said plunger. The plunger itself is shaped in the form of a shaft.

Description:
TECHNICAL FIELD  
       [0001]     Embodiments are generally related switch enclosures and other mechanically actuated devices. Embodiments are also related to plunger and other input mechanisms utilized in switching devices. Embodiments are also related to switch enclosures for maintaining plunger and other input mechanisms.  
       BACKGROUND OF THE INVENTION  
       [0002]     Many types of switch mechanisms are utilized in residential, commercial, industrial and military applications. A particular application of switch mechanisms of this type relate to pushbutton switches that comprise a plunger that is moveable relative to a base along an axis and which causes actuation of switching components when the plunger is depressed. Typically, the plunger is connected to a button that is depressible by a human finger. Some switch mechanisms cause actuation of a switch upon each depression of the button and plunger while other switch applications, referred to as alternate action devices, actuate on one push and release of the button and undo the actuation on a subsequent push and release of the button.  
         [0003]     In many switch designs and other mechanically actuated devices, the plunger is therefore utilized as the input mechanism to force some other action within the surrounding enclosure (i.e., case or housing). Plungers come in all different shapes and sizes but are usually retained in their respective enclosures by similar means. In most cases, a spring or similar feature can provide resistance to the actual movement of the plunger into the enclosure. One of the problems with conventional switch enclosure designs is that the plunger can easily move out of the necessary position for actuating or maintaining the switch. If the plunger moves, even slightly, the switch will not function properly. It is therefore desirable to provide a means by which the plunger can be retained and cannot fall out of the enclosure either through vibration or by otherwise trying to extract the plunger in the opposite direction of its intended action.  
       BRIEF SUMMARY OF THE INVENTION  
       [0004]     The following summary of the invention is provided to facilitate an understanding of some of the innovative features unique to the present invention and is not intended to be a full description. A full appreciation of the various aspects of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole.  
         [0005]     It is, therefore, one aspect of the present invention to provide for an improved mechanically actuated device.  
         [0006]     It is another aspect of the present invention to provide for an improved switch enclosure and input mechanism, such as a plunger.  
         [0007]     It is still another aspect of the present invention to provide an improved apparatus and method for maintaining a plunger within a switch enclosure.  
         [0008]     The aforementioned aspects of the invention and other aspects and advantages can now be achieved as described herein. A switch enclosure apparatus and method are disclosed. An enclosure can be provided, wherein the enclosure comprises a plurality of walls from which a cavity and one or more slots are formed. A plunger is also provided comprising one or more key portions, wherein said plunger is partially located and maintained within said cavity of said enclosure. Additionally, one or more slots can be formed from one or more walls, (e.g., side walls, top wall, bottom wall, etc.) of said enclosure for engaging said one or more of the key portions of said plunger. The plunger itself is shaped in the form of a shaft.  
         [0009]     At least one wall (e.g., a side wall) can comprise an opening, which can be covered by a removable mating cover. Additionally, a protruding portion can be configured from the mating cover for engaging one or more of the slots. A bushing can also be formed from one of the walls (e.g., top wall or top side) of the enclosure, wherein the bushing surrounds the plunger when the plunger is placed into the cavity of the enclosure. Additionally, first and second slots can be provided wherein the second slot is positioned at an angle to the first slot, such that a key portion is aligned initially with the first slot and the plunger is thereafter inserted through the bushing, followed by a rotation of the plunger until the key portion is aligned with the second slot, thereby providing a surface against which the plunger can stop.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the present invention and, together with the detailed description of the invention, serve to explain the principles of the present invention.  
         [0011]      FIG. 1  illustrates a perspective view of a plunger and a enclosure;  
         [0012]      FIG. 2  illustrates a sectional A-A view of the plunger and the enclosure illustrated in  FIG. 1 ;  
         [0013]      FIG. 3  illustrates a side sectional A-A view of the plunger and the enclosure illustrated in  FIG. 1 ;  
         [0014]      FIG. 4  illustrates a bottom perspective of the plunger and the enclosure the illustrated in  FIG. 1 ;  
         [0015]      FIG. 5  illustrates a side perspective view of the plunger and the enclosure illustrated in  FIG. 1 ;  
         [0016]      FIG. 6  illustrates bottom perspective view of a plunger and a enclosure;  
         [0017]      FIG. 7  illustrates a sectional B-B view of the plunger and the enclosure illustrated in  FIG. 6 ;  
         [0018]      FIG. 8  illustrates a side sectional B-B view of the plunger and the enclosure illustrated in  FIG. 6 ;  
         [0019]      FIG. 9  illustrates a side perspective view of the plunger and the enclosure illustrated in  FIG. 6 ;  
         [0020]      FIG. 10  illustrates a bottom view of the plunger and the enclosure illustrated in  FIG. 6 ;  
         [0021]      FIG. 11  illustrates a side perspective view of the plunger and the enclosure illustrated in  FIG. 6 ;  
         [0022]      FIG. 12  illustrates a side perspective partial cut-away view of a plunger and a enclosure, in accordance with a preferred embodiment;  
         [0023]      FIG. 13  illustrates a sectional B-B view of the plunger and the enclosure illustrated in  FIG. 12 , in accordance with a preferred embodiment;  
         [0024]      FIG. 14  illustrates a side sectional B-B view of the plunger and the enclosure illustrated in  FIG. 12 , in accordance with a preferred embodiment;  
         [0025]      FIG. 15  illustrates a side perspective view of the plunger and the enclosure illustrated in  FIG. 12 , in accordance with a preferred embodiment;  
         [0026]      FIG. 16  illustrates a bottom view of the plunger and the enclosure illustrated in  FIG. 12 , in accordance with a preferred embodiment;  
         [0027]      FIG. 17  illustrates a side perspective view of the plunger and the enclosure illustrated in  FIG. 12 , in accordance with a preferred embodiment;  
         [0028]      FIG. 18  illustrates a side perspective view of a plunger and an enclosure, in accordance with an alternative embodiment;  
         [0029]      FIG. 19  illustrates a sectional C-C view of the plunger and the enclosure illustrated in  FIG. 18 , in accordance with an alternative embodiment;  
         [0030]      FIG. 20  illustrates a side sectional C-C view of the plunger and the enclosure illustrated in  FIG. 18 , in accordance with a preferred embodiment;  
         [0031]      FIG. 21  illustrates a side perspective partial cut-away view of the plunger and the enclosure illustrated in  FIG. 18 , in accordance with an alternative embodiment;  
         [0032]      FIG. 22  illustrates a side perspective view of the plunger and the enclosure illustrated in  FIG. 18 , in accordance with an alternative embodiment;  
         [0033]      FIG. 23  illustrates a side perspective partial cut-away view of a plunger and a enclosure, in accordance with an alternative embodiment;  
         [0034]      FIG. 24  illustrates a top sectional B-B view of the plunger and the enclosure illustrated in  FIG. 23 , in accordance with an alternative  25  embodiment;  
         [0035]      FIG. 25  illustrates a side perspective view of the plunger and the enclosure illustrated in  FIG. 23 , in accordance with an alternative embodiment;  
         [0036]      FIG. 26  illustrates a side perspective cut-away view of the plunger and the enclosure illustrated in  FIG. 23 , in accordance with an alternative embodiment;  
         [0037]      FIG. 27  illustrates a side A-A and B-B view of the plunger and the enclosure illustrated in  FIG. 23 , in accordance with an alternative embodiment;  
         [0038]      FIG. 28  illustrates a side A-A view of the plunger and the enclosure illustrated in  FIG. 23 , in accordance with an alternative embodiment; and  
         [0039]      FIG. 29  Illustrates an exploded view of the plunger and the enclosure illustrated in  FIG. 23 , in accordance with an alternative embodiment.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0040]     The particular values and configurations discussed in these non-limiting examples can be varied and are cited merely to illustrate at least one embodiment and are not intended to limit the scope of the invention.  
         [0041]     In many switch designs and other mechanically actuated devices, a plunger can be used as the input mechanism to force some other action within the surrounding enclosure. In most cases a spring or similar feature provides resistance to the actual movement of the plunger into the enclosure. It is necessary to provide a means by which the plunger is retained and cannot fall out of the enclosure either through vibration or by otherwise trying to extract the plunger in the opposite direction of its intended action. Plungers come in all different shapes and sizes but are usually retained in their respective enclosures by similar means.  
         [0042]      FIGS. 1-5  illustrate varying views of a plunger  108  and an enclosure  100 .  FIG. 1  illustrates a perspective view of the plunger  108  and the enclosure  100 . Enclosure  100  generally includes a top portion or topside  113  and walls  104 ,  106  and  110 ,  102 . In  FIG. 1 , plunger  108  is shown located within enclosure  100 . Plunger  108  generally includes a retaining ring or section  112 , while enclosure  100  includes a bushing wall  111 , which comes into contact with retaining ring or section  112  of plunger  108 . Wall  102  is generally located opposite wall  110 , while wall  104  is located opposite wall  106 . A top wall or topside  113  of enclosure  100  is also shown in  FIG. 1 .  
         [0043]      FIG. 2  illustrates a sectional A-A view of the plunger  108  and the enclosure  100  illustrated in  FIG. 1 . The topside  113  is shown in  FIG. 2  and a portion of plunger  108  protruding through topside  113  of enclosure  100 .  FIG. 3  illustrates a side sectional A-A view of the plunger  108  and the enclosure  100  illustrated in  FIG. 1 .  FIG. 4  illustrates a bottom perspective of the plunger  108  and the enclosure  100  illustrated in  FIG. 1 . Walls  102 ,  104 ,  106  and  110  are also shown in  FIG. 4 , along with retaining ring or section  112  of plunger  108 .  FIG. 5  illustrates a side perspective view of the plunger  108  and the enclosure  100  illustrated in  FIG. 1 .  
         [0044]     Walls  102  and  106  are also shown in  FIG. 5 , along with the top wall or topside  113 . Diameter  109  is also shown in  FIG. 5 , which represents the diameter of the opening through which plunger  108  protrudes through topside  113  of enclosure  100 . Plunger  108  can be configured to include a central portion  119  thereof. Note that in  FIGS. 1-5  herein, identical or similar parts or elements are indicated by identical reference numerals.  FIGS. 1-5  thus represent varying view of the same enclosure  100  and plunger  108 .  
         [0045]      FIGS. 1-5  indicate that the plunger  108  itself includes an area or section  112  (i.e., a retaining ring) that has a diameter larger than the bushing diameter  109  of the enclosure  100 . The plunger  108  is thus inserted from inside the enclosure  100  and the larger diameter section  112  on the plunger  108  stops against the bushing wall  111 , preventing it from coming out through the topside  113  of the enclosure  100 . In cases where the enclosure  100  is split in half, the plunger  108  can be assembled in a top down fashion. These are simple methods with no extra parts necessary to accomplish the task.  
         [0046]     In certain situations, however, the design of the enclosure may force the plunger  108  to be inserted from outside the enclosure  100 . An example would be if the plunger  108  is too long to assemble from inside the enclosure  100  or if a portion of the plunger  108  that resides outside the enclosure  100  has a larger diameter than the bushing diameter  109  of the enclosure  100 . In these cases, a plunger stop can be added to the plunger  108  after its initial assembly into the enclosure  100 . An example would be the installation of a snap ring or other part that increases the diameter of the plunger  108  in the desired area or section  112  along the plunger  108  to allow it to act as a plunger stop. This method is very effective, but adds at least one additional part and increases complexity to the assembly.  
         [0047]      FIGS. 6-11  illustrate varying views of a plunger  212  and an enclosure  200 . The plunger  212  of  FIGS. 6-11  is analogous to the plunger  108  of  FIGS. 1-5 , with modifications thereof.  FIG. 6  illustrates a bottom perspective view of plunger  212  and the enclosure  200 .  FIG. 7  illustrates a sectional B-B view of the plunger  212  and the enclosure  200  illustrated in  FIG. 6 .  FIG. 8  illustrates a side sectional B-B view of the plunger  212  and the enclosure  200  illustrated in  FIG. 6 .  FIG. 9  illustrates a side perspective view of the plunger  212  and the enclosure  200  illustrated in  FIG. 6 .  FIG. 10  illustrates a bottom view of the plunger  212  and the enclosure  200  illustrated in  FIG. 6 . Likewise,  FIG. 11  illustrates a side perspective view of the plunger  212  and the enclosure  200  illustrated in  FIG. 6 . Note that in  FIGS. 6-11  herein, similar or identical parts or elements are indicated by identical reference numerals.  
         [0048]     In  FIGS. 6-11 , plunger  212  includes a protrusion  201  along the shaft of plunger  212 . Such a protrusion  201  acts as a “key”. The enclosure  200  is configured to include a complimentary “keyway slot”  202 , which allows the plunger  212  to be inserted from outside the enclosure  200 . The plunger  212  can be then rotated to allow the key or protrusion  201  from the plunger to stop on the bushing wall  210  of the enclosure  200 . This approach eases assembly by eliminating the need for extra parts such as the retaining ring  112  shown in  FIGS. 1-5 . The problem with this method, however, is that through shock, vibration or physical rotation of the plunger  212 , the key or protrusion  201  configured on the plunger  212  can be forced to once again align itself with the keyway slot  202  in the enclosure  200  allowing it to disengage itself from the enclosure  200 .  
         [0049]      FIGS. 12-17 ,  FIGS. 18-22 , and  FIGS. 23-29  respectively represent three alternative embodiments of the present invention.  FIGS. 12-17  represent a preferred embodiment, while  FIGS. 18-22  and  FIGS. 23-29  illustrate alternative embodiments. The three embodiments described below generally can be implemented to accomplish the task of retaining a plunger for situations in which the plunger can only be inserted from outside the enclosure due to necessary design constraints.  
         [0050]     Note that in  FIGS. 12-17  herein, similar or identical parts are indicated by identical reference numerals.  FIG. 12  illustrates a side perspective partial cut-away view of a plunger  312  and an enclosure  300 , in accordance with a preferred embodiment. Enclosure  300  includes a wall  306  which is located opposite a wall  309 . Enclosure  300  also includes a wall  308 , which is located opposite a wall  310 . Enclosure  300  additionally includes a bushing or bushing wall  314 .  
         [0051]      FIG. 13  illustrates a sectional B-B view of the plunger  312  and the enclosure  300  illustrated in  FIG. 12 , in accordance with a preferred embodiment.  FIG. 13  also illustrates a topside  318  of enclosure  300  and a slot  303  formed from bushing wall  314 .  FIG. 14  illustrates a side sectional B-B view of the plunger  312  and the enclosure  300  illustrated in  FIG. 12 , in accordance with a preferred embodiment.  FIG. 15  illustrates a side perspective view of the plunger  312  and the enclosure  300  illustrated in  FIG. 12 , in accordance with a preferred embodiment. The view depicted in  FIG. 15  illustrates the plunger  312  prior to entry to enclosure  300  through a hole  316 , which is configured from top wall or topside  318 . Walls  306  and  308  are also depicted in  FIG. 15 . Also shown in  FIG. 15  is a key portion or plunger key  301 .  
         [0052]      FIG. 16  illustrates a bottom view of the plunger  312  and the enclosure illustrated in  FIG. 12 , in accordance with a preferred embodiment. In  FIG. 16 , two slots are indicated, including slot  302  and slot  303 .  FIG. 17  illustrates a side perspective view of the plunger  312  and the enclosure  300  illustrated in  FIG. 12 , in accordance with a preferred embodiment.  FIG. 17  also illustrates walls  308 ,  306  and topside  318 .  
         [0053]      FIGS. 12-17  thus indicate a configuration that is analogous to that described herein with respect to  FIGS. 6-11 , except that an additional keyway slot is added to the enclosure  300  originating from within the enclosure  300 , but not fully extending through the bushing wall  314  to the outside. This additional keyway slot can be positioned at an angle (e.g.,  450 ,  600 ,  900 , etc.) to the original slot  302 , which is analogous to the slot  202  depicted in  FIGS. 6-11 .  
         [0054]     In the configuration of  FIGS. 12-17 , the plunger key  301  can be aligned with the first keyway slot  302 , and then the plunger  312  can be inserted all the way through the bushing  314  (i.e., bushing wall) of enclosure  300 , and then rotated until the plunger key  301  is aligned with the secondary keyway slot  303 . This slot  303  does not fully extend to the outside of the enclosure  300 , and thus provides a surface for the plunger key  301  to stop against. The depth of the secondary slot  303  should be slightly longer than the maximum plunger travel to prevent the plunger  312  from being able to rotate back to the point where the plunger key  301  is again aligned with the first keyway slot  302  and can become disengaged from the enclosure  300 .  
         [0055]      FIGS. 18-22  represent a modification to the embodiment depicted in  FIGS. 12-17 . In  FIGS. 18-22 , similar or identical parts are indicated by identical reference numerals. Note that enclosure  400  of  FIGS. 18-22  is analogous to enclosure  300  of  FIGS. 12-17 , except that enclosure  400  is modified with the extra features depicted in  FIGS. 18-22 .  FIG. 18  illustrates a side perspective view of a plunger  412  and the enclosure  400 , in accordance with an alternative embodiment. In  FIG. 18 , a side  406  is shown, along with a side  408 . A topside  410  is also shown through which a portion of plunger  412  protrudes external from enclosure  400 . A mating cover  409  is also shown in  FIG. 18 . Such a cover  409  can be removed and then re-attached to enclosure  400 .  
         [0056]      FIG. 19  illustrates a sectional C-C view of the plunger and the enclosure illustrated in  FIG. 18 , in accordance with an alternative embodiment. In  FIG. 19 , a bushing wall or bushing  414  is depicted, through which plunger  412  is positioned within enclosure  400 .  FIG. 20  illustrates a side sectional C-C view of the plunger  412  and the enclosure  400  illustrated in  FIG. 18 , in accordance with a preferred embodiment.  FIG. 20  additionally depicts the mating cover  409 , which includes a protruding feature  404 . A bottom side or bottom wall  422  of enclosure  400  is also indicated in  FIGS. 19 and 20 .  FIG. 20  specifically indicates a central portion or cavity  415  of enclosure  400 . Additionally, plunger  412  includes a plunger key  401 .  
         [0057]      FIG. 21  illustrates a side perspective partial cut-away view of the plunger  412  and the enclosure  400  illustrated in  FIG. 18 , in accordance with an alternative embodiment. In  FIG. 21 , mating cover  409  and protruding feature  404  thereof are also depicted, along with bushing  414 , wall  408 , bottom wall  422  and cavity  415 . A wall  411  is also shown in  FIG. 21 , which is located opposite the wall  406  depicted in  FIGS. 18 and 22 .  FIG. 22  illustrates a side perspective view of the plunger  412  and the enclosure  400  illustrated in  FIG. 18 , in accordance with an alternative embodiment.  
         [0058]     In addition to the presence of a keyway slot  402  configured in the bushing  414 , an additional slot  403  can be configured, which is positioned orthogonal to the plunger/bushing axis. As indicated in  FIGS. 18-22 , the slot  403  can generally extend to the plunger stop surface at the bottom of the bushing  414  in the enclosure  400 . The mating cover  409  generally includes the protruding feature  404  which can fill this second slot  403  and thereby prevent the plunger  412  from being able to back out of its intended position even if rotated to align the plunger key  401  with the first slot  402  passing through the entire length of the bushing  414 .  
         [0059]     In  FIGS. 23-29 , similar or identical parts are indicated by identical reference numerals.  FIG. 23  illustrates a side perspective partial cut-away view of a plunger  512  and an enclosure  500 , in accordance with an alternative embodiment. Enclosure  500  includes a wall  503  and a wall  506 . A mating cover  507  can be positioned at an opening of wall  506 . Cover  507  includes a protruding portion  502  which comes into contact with plunger  512 . Wall  503  is located opposite a wall  509 , which is identified in  FIGS. 24 and 27 .  
         [0060]      FIG. 24  illustrates a top sectional B-B view of the plunger  512  and the enclosure  500  illustrated in  FIG. 23 , in accordance with an alternative embodiment. In  FIG. 24 , mating cover  507  and a protruding portion  502  thereof are also shown, along with walls  503  and  509 .  FIG. 25  illustrates a side perspective view of the plunger  512  and the enclosure  500  illustrated in  FIG. 23 , in accordance with an alternative embodiment.  FIG. 26  illustrates a side perspective cut-away view of the plunger  512  and the enclosure  500  illustrated in  FIG. 23 , in accordance with an alternative embodiment. In  FIG. 26 , bottom side or bottom wall  508  is also indicated, which is located opposite top wall or top side  504  depicted in  FIG. 23 . Plunger  512  is configured to include an undercut portion  501  which can come into contact with the protruding portion  502  of cover  507 .  
         [0061]      FIG. 27  illustrates a side A-A and B-B view of the plunger  512  and the enclosure  500  illustrated in  FIG. 23 , in accordance with an alternative embodiment.  FIG. 28  illustrates a side A-A view of the plunger  512  and the enclosure  500  illustrated in  FIG. 23 , in accordance with an alternative embodiment. In  FIG. 28 , a central portion or cavity  515  of enclosure  500  is further indicated.  FIG. 29  Illustrates an exploded view of the plunger  512  and the enclosure  500  illustrated in  FIG. 23 , in accordance with an alternative embodiment. In  FIG. 29 , bushing  511  is also indicated, along with plunger  512  prior to entry to enclosure  500  and prior to cover  507  coming into contact with plunger  512 .  
         [0062]      FIGS. 23-29  represent an embodiment that does not require the use of plunger keys or keyways in the bushing of the enclosure. Instead, it requires the plunger  512  to be configured with an undercut portion  501  for a section of its length such that that the diameter of the undercut portion  501  is less than the diameter of the bushing  511 . A protruding feature  502  can be configured on or with the mating cover  507 , which can then surround the plunger  512  in this undercut section  501  to provide the necessary stop for the plunger  512 . The length of the undercut section  501  can be configured such that the appropriate plunger travel is attainable. The configuration depicted in  FIGS. 23-29  is advantageous over that described herein with respect to  FIGS. 18-22  in cases where the plunger  512  would be machined rather than molded due to the added complexity involved in trying to machine a key into the plunger. It is very easy to machine the undercut section.  
         [0063]     Based on the foregoing description, it can be appreciated that embodiments described herein refer to three different methods and configurations for accomplishing the task of retaining the plunger for situations in which the plunger can only be inserted from outside the enclosure due to necessary design constraints. The first method or configuration,  FIGS. 12-17 , is similar to that of  FIGS. 6-11 , except that an additional keyway slot is added to the enclosure originating from within the enclosure but not fully extending through the bushing wall to the outside. This additional keyway slot is positioned at some angle such as 90° to the original slot.  
         [0064]     The method and configuration of  FIGS. 12-17  requires the plunger key (be aligned with the first keyway slot and then the plunger is inserted all the way through the enclosure bushing and then rotated until the plunger key is aligned with the secondary keyway slot. This slot does not fully extend to the outside of the enclosure and thus provides a surface for the plunger key to stop against. The depth of the secondary slot should be slightly longer than the maximum plunger travel to prevent the plunger from being able to rotate back to the point where the plunger key is again aligned with the first keyway slot and can become disengaged from the enclosure.  
         [0065]     The second method and configuration is described herein with respect to  FIGS. 18-22  and is a modification to  FIGS. 12-17 . In addition to the keyway slot in the bushing, another slot is provided, which is positioned orthogonal to the plunger/bushing axis. The slot extends to the plunger stop surface at the bottom of the bushing in the enclosure. The mating cover would then include a protruding feature or protruding portion, which fills this second slot and thus prevents the plunger from being able to back out of its intended position even if rotated to align the plunger key with the first slot passing through the entire length of the bushing.  
         [0066]     The third and final method and configuration is described herein with respect to  FIGS. 23-29 , and does not require the use of plunger keys or keyways in the bushing of the enclosure. Instead, it requires the plunger to be undercut for a portion of its length such that the diameter is less than that of the bushing. A protruding feature or protruding portion formed on or from the cover can then surround the plunger in this undercut section and provide the necessary stop for the plunger. The length of the undercut section would be such that the appropriate plunger travel is attainable.  
         [0067]     The embodiments and examples set forth herein are presented to best explain the present invention and its practical application and to thereby enable those skilled in the art to make and utilize the invention. Those skilled in the art, however, will recognize that the foregoing description and examples have been presented for the purpose of illustration and example only. Other variations and modifications of the present invention will be apparent to those of skill in the art, and it is the intent of the appended claims that such variations and modifications be covered.  
         [0068]     The description as set forth is not intended to be exhaustive or to limit the scope of the invention. Many modifications and variations are possible in light of the above teaching without departing from the scope of the following claims. It is contemplated that the use of the present invention can involve components having different characteristics. It is intended that the scope of the present invention be defined by the claims appended hereto, giving full cognizance to equivalents in all respects.