Abstract:
An electrical switch is disclosed having improved operational characteristics wherein when a operating handle is rotated from an OFF position to an ON position the switch provides slow motion which accelerates as the operating handle is rotated to a full open position and then provides rapid establishment of electrical contact. The operating handle having a cam that when rotated from the ON position to the OFF position forces a cam follower downwards. As a result, a bridge having coil springs connected to the cam follower is forced downwards to separate at least one electrical contact placed in proximity to the bridge.

Description:
[0001]     Under 35 CFR 119(e), this application claims the benefit of the filing date of a provisional application having Ser. No. 60/648,793 which was filed on Jan. 31, 2005. 
     
    
       [0002]     This application includes material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction of the patent disclosure, as it appears in the Patent and Trademark Office files or records, but otherwise reserves all rights.  
       FIELD OF THE INVENTION  
       [0003]     The present invention relates to the field of electrical switches. More specifically, this invention relates to switches for use in alternating currents.  
       BACKGROUND OF THE INVENTION  
       [0004]     Lever actuated switches are common in the art and are used to provide a means to conveniently and affirmatively switch electrical current. Many variations of switches exist that utilize a lever which acts upon a plunger or similar structure to engage or disengage electrical contacts and thereby establish or terminate electrical service to one or more loads. An example of a patented switch of this type is disclosed in U.S. Pat. No. 4,400,603. This patent discloses a switch for use in alternating current (AC) circuits wherein a pivotally mounted operating handle accepts a pivot pin at one end of a link member. A pivot pin at the other end of the link member fits into a brush lifter. Angular motion of the operating handle produces a rectilinear motion in the brush lifter which results in opening and closing of the switch contacts. An arc shield disposed within the switch encircles one out of each pair of contacts, and protects the switch mechanism from destructive effects of contact arcing.  
         [0005]     A need exists for an improved switch that incorporates a reduced number of moving parts. This improved switch should be enabled to be produced at reduced cost. Furthermore, this switch should provides improved operational characteristics.  
         [0006]     The present invention is directed to overcoming, or at least reducing the effects of one or more of the problems set forth above.  
       SUMMARY OF THE INVENTION  
       [0007]     To address the above-discussed deficiencies of electrical switches, the present invention teaches an electrical switch that provides enhanced operational characteristics wherein the rotary motion of an operating handle is translated into a linear motion through the incorporation of a cam follower. Unique geometry of a cam operating upon the cam follower translates into a switching action which provides for an initial slow break that accelerates as the operating handle is rotated to a full open position. The cam follower then rapidly establishes contact and minimizes arcing when the switch is closed.  
         [0008]     In particular, the operating handle having a cam is in cooperative alignment with a cam follower such that when the operating handle is rotated from an OFF position to an ON position, the cam causes the cam follower to move a bridge having coil spring into contact with at least one electrical contact. In the alternative, when the operating handle is rotated from the ON position to the OFF position, the cam causes the cam follower to separate the bridge apart from the electrical contact.  
         [0009]     Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.  
         [0010]     These and other features and advantages of the present invention will be understood upon consideration of the following detailed description of the invention and the accompanying drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings in which like reference numbers indicate like features and wherein:  
         [0012]      FIG. 1  illustrates the top view of a three-pole switch in accordance with the present invention with the operating handle  10  in the ON position;  
         [0013]      FIG. 2  displays a side elevation view of the switch  100  of  FIG. 1 ;  
         [0014]      FIG. 3  illustrates a cross-sectional view of switch  100  of  FIG. 1  taken along Section line  3 - 3  where the cut extends through switch  100 ;  
         [0015]      FIG. 4  is a side view of operating handle  10 ;  
         [0016]      FIG. 5  is an end view of operating handle  10 ;  
         [0017]      FIG. 6  depicts a cross-sectional view of switch  100  of  FIG. 1  taken along Section line  6 - 6  where the cut extends through switch  100 ;  
         [0018]      FIG. 7  is a plan view of the bottom of the switch  100  of  FIG. 1 ;  
         [0019]      FIG. 8  illustrates operating handle  10 , cam  80  and cam follower  50  in two positions to demonstrate the switch position feature; and  
         [0020]      FIG. 9  shows the placement of insulating arc shield  90 .  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0021]     The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.  
         [0022]     The present invention relates to a switch having improved operational characteristics, with relatively fewer parts. Referring to the drawings,  FIG. 1  illustrates the top view of a three-pole switch in accordance with the present invention with the operating handle  10  in the ON position. The switch enclosure  12 , such as of molded insulating material, is large enough to contain three poles. However, it will be understood that the invention applies as well to switches of less or greater complexity which contain a different number of poles. The cover arrangement includes switch enclosure  12  and faceplate  14 . Faceplate  14 , such as of metal, is mounted to enclosure  12  by two faceplate bolts,  24  and  26 . These faceplate bolts,  24  and  26 , serves to hold operating handle pivot pin  40  (shown in  FIG. 3 ) on operating handle  10  in slots (not shown) of enclosure  12 . Mounting holes  22  and  28  are provided in face plate  14 , for mounting the switch on a control panel. Six conductor clamp bolts  16 ,  18 ,  20 ,  30 ,  32 , and  34  are shown to accommodate the three poles of the switch shown in this embodiment.  
         [0023]      FIG. 2  is a side elevation view of the switch of  FIG. 1 , showing conductor clamp bolts  30 ,  32 , and  34  for a circuit which will be controlled by the switch. A like number of conductors,  16 ,  18  and  20 , shown in  FIG. 1  is provided on the opposite side of the switch (not shown in  FIG. 2 ). Referring back to  FIG. 2 , this first embodiment of the present invention comprises a base  36  and a cover arrangement including switch enclosure  12  and faceplate  14 . The switch enclosure  12  and faceplate  14  are held together by faceplate bolts  24  and  26  (shown in  FIG. 1 ).  
         [0024]      FIG. 3  depicts a cross-sectional view of switch  100  of  FIG. 1  taken along Section line  3 - 3  where the cut extends through switch  100  revealing coil springs  52 - 66 , cam  80  of operating handle  10 , and cam follower  50 . As can be seen from  FIG. 3 , cam  80  is integrated into operating handle  10  such that when operating handle  10  is rotated, cam  80  acts upon cam follower  50  which engages bridges  82 - 86  which is part of a contact making and contact breaking mechanism. The action of cam follower  50  upon bridges  82 - 86  causes a downward motion of bridges  82 - 86  resulting in contact opening and placing operating handle  10  in a locked position.  
         [0025]     During the actuation of operating handle  10  to its locked position, the resultant downward movement of bridges  82 - 86  compresses coil springs  52 - 62  which remain compressed as long as operating handle  10  remains in the locked position. When the position of operating handle  10  is reversed (moved out of locked position), coil springs  52 - 62  expand and bring bridges  82 ,  84 , and  86  in contact with respective conductors,  16 ,  18 ,  20  and, thereby establishing full contact position. These same bridges  82 ,  84 , and  86  make contact with a like number of respective conductors,  30 ,  32 , and  34 , shown in  FIG. 1  is provided on the opposite side of the switch (not shown in  FIG. 3 ). Auxiliary springs  64  and  66  located inside cam follower  50  bias follower  50  to its maximum upward position thereby separating bridge  82 - 86  from cam follower  50  and creating an over-travel position for operating handle  10 .  
         [0026]      FIG. 4  is a side view of operating handle  10 , which shows how operating handle pivot pin  40  sits off center with respect to center line A-A. Operating handle stops  82  and  84  are also shown.  
         [0027]      FIG. 5  is an end view of operating handle  10 , showing how operating handle pivot pin  40  extends from both sides of the operating handle  10 . Operating handle stops  86  and  88  are also shown positioned opposite operating handle stops  82  and  84 .  
         [0028]      FIG. 6  depicts a cross-sectional view of switch  100  of  FIG. 1  taken along Section line  6 - 6  where the cut extends through switch  100  revealing bridge  84  in contact with coil springs  56 ,  58 , and  68 . Bridge  84  includes contacts  70   a  and  70   c  for making contact with another pair of contacts  70   b  and  70   d . Specifically, in operation, when cam  80  of operating handle  10  is rotated to the OFF position, cam follower  50  compresses coil spring  56  which forces bridge  84  downward. The downward motion of bridge  84  compresses coil springs  58  and  68 . Contacts  70   a  and  70   c  separate from contacts  70   b  and  70   d  breaking connection with the circuits derived by conductors  32  and arm  98 , on one side, and conductor  18  and arm  99 , on the opposite side.  
         [0029]     Accordingly, in operation, when cam  80  of operating handle  10  is rotated to the ON position, cam follower  50  is no longer held in the locked OFF position and is forced upwards by coil springs  56 ,  58  and  68 . Bridge  84  is forced upwards by coil springs  58  and  68  such that contacts  70   a  and  70   c  meet respective contacts  70   b  and  70   d . The connection through contacts  70   a  and  70   b  enables current to flow through arm  98  to conductor  32  and into the circuit being controlled by switch  100 . In the same like fashion, the connection through contacts  70   c  and  70   d  enables current to flow through arm  99  to conductor  18  and into the circuit being controlled by switch  100  when handle  10  is rotated to the ON position.  
         [0030]      FIG. 7  is a plan view of the bottom of the switch  100  of  FIG. 1 , showing faceplate bolts  24  and  26 . Six conductor clamp bolts  16 ,  18 ,  20 ,  30 ,  32 , and  34  are shown to accommodate the three poles of the switch shown in this embodiment. As earlier referenced, mounting holes  22  and  28  are provided in face plate  14 , for mounting the switch on a control panel, wherein face plate  14  extends beyond either end of base  36 .  
         [0031]      FIG. 8  illustrates the switch position feature. When operating handle  10  pivots around pivot pin  40 , from position A to position B, cam follower  50  moves from position C to position D. Specifically, operating handle stops  82  and  84  of cam  80  ride along the ridged surface of cam follower  50  when operating handle  10  pivots around pivot pin  40 . The unique ridged surface of cam follower  50  ensures that operating handle  10  can only stop in the full ON or full OFF position. In the ON position, operating handle  10  is in position A. Referring back to  FIG. 6 , cam follower  50  is no longer held in the locked OFF position and is forced upwards by coil springs  56 ,  58  and  68 . In the OFF position, operating handle  10  is in position B. Accordingly, referring to  FIG. 6 , cam  80  forces cam follower  50  to compress coil spring  56  which forces bridge  84  downward.  
         [0032]      FIG. 9  shows the placement of insulating arc shield  90  around any of the stationary conductor clamp bolts  16 ,  18 ,  20 ,  30 ,  32 , and  34  shown in  FIGS. 1-7 . By completely encircling stationary contact  16 , for example, the arc shield  90  provides maximum protection for structures in the vicinity of stationary contact  16 . In this embodiment, arc shield  90  is held in place by virtue of the fact that the edge  96  of the arc shield  90  fits in a gap between enclosure component  12  and base  36 , as shown in  FIG. 2 .  
         [0033]     While the invention has been described in detail and with reference to a specific embodiment thereof, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof. For example switch  100  can be manufactured as a two pole or three pole device respectively. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.  
         [0034]     Advantages of this design include but are not limited to an electrical switch having a high performance, simple, and cost effective design.  
         [0035]     The reader&#39;s attention is directed to all papers and documents which are filed concurrently with this specification and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.  
         [0036]     All the features disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.  
         [0037]     The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.