US 3739120 A
Description (OCR text may contain errors)
ilnited States Patent 1 Starr June 12, 1.973
[ FLEXIBLE SWITCH SUPPORT AND TERMINAL CONNECTOR Robert V. Starr, Amity, Pa.
 Assignee: McGraw-Edison Company, Elgin, Ill.
 Filed: July 15, 1971 i  Appl. No.2 162,923
Primary Examiner-Robert S. Macon Attorney John Carl Gealow  ABSTRACT A movable electrically conductive connector for a switch is disclosed which comprises a support structure having a pair of spaced apart straps each comprising a plurality of thin, flexible, conductive laminated plates. The straps have a superimposed position with the corresponding ends of each of the straps being clamped to a fixed terminal and the opposite ends of the straps each being clamped to the movable stem of a movable switch contact. The straps are movable with the contact stem in a substantially straight line perpendicular to the horizontal planes of the straps over a small travel distance of the contact stem.
5 Claims, 3 Drawing Figures BACKGROUND OF THE INVENTION This invention relates to a movable support for a switch which also acts as an electrical connector and guide for the movable contact of a switch. The invention has particular, but not exclusive, application to a vacuum switch.
The movable contact and contact stern of a vacuum switch utilized in a circuit breaker requires a movable electrical connector which moves with the contact and stem and connects the vacuum switch in the electrical circuit with which the interrupter is associated. It is also most convenient to support a vacuum switch by affixing the stems of the fixed and movable contact which extend from within the vacuum enclosure of the vacuum switch to a mounting structure. However, since the stem which extends from the movable contact within the vacuum container must be movable, the supporting structure connected to it must also be movable. Thus, both the electrical connector for the movable contact stern and the part of the switch support connected to the movable stem must also be movable. These connections should preferably be made without interference with the desired movement of the movable contact and its stem.
Typical prior art movable electrical connectors and movable supports comprise sliding current transfer joints which provide both support and current conduction. Also, it is known to rigidly attach a separate flexible cable to the movable contact stem for current transfer and use a sliding support only for support of the switch. In both of the foregoing arrangements, problems of interference with the movement of the movable contact stem frequently arise. Also, the number of items of hardware required to make the known type of supports and connectors is excessive and adds to the cost of the overall circuit breaker.
SUMMARY OF THE INVENTION It is accordingly a general object of the invention to provide a simple and economical movable connector for an electrical switch which simultaneously supports the switch, acts as a stable guide for the movable contact of the switch and serves as an electrical connection between the movable contact and the circuit in which the switch is connected. A more specific object of the invention is to provide a movable connector of the above described type for a vacuum switch.
The objects of the invention are accomplished by providing a movable connector having a pair of flexible electrically conductive straps each comprising a plurality of thin, flexible, laminated plates. The plates have a spaced apart superimposed position with corresponding ends of the straps being rigidly clamped to a stationary terminal and the opposite corresponding ends of the straps being clamped to the movable support arm of a movable switch contact. The pair of straps, the portion of the stationary terminal between the ends of the straps, and the portion of the movable support arm between the opposite ends of the straps forming a fourbar parallelogram. The ends of the straps clamped to the movable contact arm move in a substantially straight line with the contact arm and provide a stable guide for movement of the contact arm. The straps also provide an electrical connection between the movable contact and the circuit with which the switch is associated. Moreover, the two laminated straps provide a stable support for the entire electrical switch.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an elevational view of the movable connector and a vacuum switch which it supports with the contacts of the vacuum switch in an engaged position;
FIG. 2 shows an elevational view of the movable connector and the switch shown in FIG. 1 with the contacts of the switch in an open position; and
FIG. 3 is a plan view partially in cross section of the movable connector taken along lines 3-3 of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring generally to the drawings, a movable connector and support member 2 is shown mounted on breaker studs 14 and 16. The connector and member 2 includes a terminal member 50 and a mounting board 4. The terminal member 50 is affixed to the mounting board 4 by means such as bolts 6 and nuts 8 and bolts 10 and nuts 12. A vacuum switch 20 includes an enclosure 22 containing a vacuum, an end 24 affixed to the connector and support member 2 and an end 26 also affixed to the member 2. The vacuum switch 20 also includes a fixed contact 30 positioned within the enclosure 22 and having a support arm or stem 32 extending out of the enclosure 22 in sealed relationship therewith. The stem 32 is attached to the clamping bracket 38 by means of bolts and nuts 34 and 36. The vacuum switch 20 includes a movable contact 40 positioned within the vacuum enclosure 22 and having a support arm or stem 42 extending out of the enclosure 22. As shown in FIG. 1, the enclosure 22 includes a flexible bellows 44 sealing the enclosure 22 and affixed to the stem 42 in sealing relationship therewith. The movable contact 40 and stem 42 are movable along a substantially straight line into and out of engagement with the fixed contact 30. When the movable contact 40 and fixed contact 30 are in engagement, an electrically conducting circuit is completed through the stud 16 the clamping bracket 38, the fixed stem 32, the contacts 30 and 40, the movable stem 42, the connector and support member 2 and the stud 14. This circuit is interrupted by the vacuum switch 20 when the movable contact 40 is moved out of engagement with the fixed contact 30.
The movable connector and support member 2 includes the terminal member 50 and mounting board 4, as previously stated, a clamping block 52 and electrically conductive straps 54 and 56. The clamping block 52 is clamped to the movable stem 42 by means such as bolt 58 and nut 60. The strap 54 has bifurcated ends 62 and 64 and the strap 56 has bifurcated ends 66 and 68. The bifurcated ends 62 and 66 of the straps S4 and 56 are affixed to the movable stem 42 by means of the clamping block 52, the clamping cross members 70 and 72 and the bolts 74 and nuts 76. The ends 64 and 68 of straps 54 and 56 are affixed to the terminal member 50 by means of clamping cross members 78 and 80, bolts 82 and nuts 84. The straps 54 and 56, the portion of the clamping block 52 between bifurcated ends 62 and 66 of the straps 54 and 56, and the portion of the terminal member 50 between ends 64 and 68 of straps 54 and 56 form a four-bar parallelogram. The strap 54 is comprised of a group of flexible laminated plates 94 and the strap 56 is comprised of a group of flexible laminated plates 96. Each of the laminated plates 94 and 96 may include an electrically conductive material such as copper and alloys thereof.
An operator means 100 for the vacuum switch includes a linkage means 102 having a link member 106 pivotally connected to rod member 104. The link member 106 is also pivotally mounted on the member 28 projecting from and affixed to member 2 by bolt 86. The operator means 100 also includes a double lever arm 108 pivotally mounted on the member 28 and also pivotally attached to the movable stem 42 by means of a stem extension 110 and pin 112. A spring means 120 includes a bolt 122 slidably connected to the end 114 of double lever arm 108 and pivotally connected to the link member 106 intermediate its pivot points 116 and 118. The bolt 122 is attached to the double lever arm 108 by means of bushing 124 which is pivotally mounted on the end 114 of arm 108. The'spring means 120 includes coaxially mounted springs 126 and 128 retained in position on the bolt 122 by slidable washers 130 and 132. A nut 134 threadably attached to the bolt 122 retains the latter on the lever arm 108 and provides a stop for motion of the bolt 122 in the right hand direction relative to the view of FIG. 1.
With reference to FIGS. 1 and 2, when the movable contact 40 moves from the engaged position shown in FIG. 1 to the disengaged position shown in FIG. 2, the ends 62 and 66 of the straps 54 and 56 move with the contact stem 42 and clamping block 52. This movement of the ends 62 and 66, two adjacent corners of the four-bar parallelogram, is through an arc, however, for the small deflection of the straps 54 and 56 involved, the motion is substantially in straight line in the direction of the motion of the movable contact 40. The straps 54 and 56 thus act as a guide for the straight line movement of the contact stem 42 and movable contact 40. The spaced apart position of the straps 54 and 56 and the clamping of the straps 54 and 56 at their opposite ends results in a particularly stable guide for the contact stem 42. The straps 54 and 56 and thus the movable connector and support member 2 also support the end 24 of the vacuum switch 20 in a movable mode. Moreover, one or both of the straps 54 and 56 serve as the electrical connection between the movable contact 40 and the terminal member 50. The three fold function of the movable connector and support member 2 may be summarized as providing a stable guide for substantially straight line motion of the movable contact 40, movably supporting the vacuum switch 20 in a stable manner and providing an electrical connection for the movable contact 40 and the circuit breaker in which the vacuum switch 20 is utilized.
It is well known that atmospheric pressure exerts a force against a flexible bellows such as used in the disclosed vacuum switch 20 which exceeds the pressure of the vacuum within the closure 22. Since the bellows 44 is attached to the movable contact stem 42, the force of atmospheric pressure is transferred to the stem 42 to thereby provide a force tending to hold the movable contact 40 in engagement within the fixed contact 30. Where the vacuum switch operating means is balanced to apply equal force in either a closing or opening direction, the additional atmospheric force holding the contacts in engagement is not desired. The straps 54 6 and 56 are resilient and are flexed 1n the direction of the fixed contact 30 when the fixed contact 30 and movable contact 40 are in engagement. Thus the straps 54 and 56, when in the position shown in FIG. 1 correspond to the contact engaged position, provide disengaging force on the contacts 30 and 40 which tends to counterbalance the atmospheric closing force on the contacts 30 and 40.
The operator means provides engaging and disengaging force to the movable contact 40 by movement of the rod member 104 along the direction of the axis of stem 42. When the rod member 104 is moved generally in a right hand direction relative to the view of FIG. 1, the link 106 will pivot about pivot point 118 and opening force will be applied through bolt 122 and nut 134 to the double lever arm 108. In turn, the lever arm 108 pivots about pivot point 118 and transmits upward force along the axis of the movable contact stem 42 to disengage the movable contact 40 from the fixed contact 30. During operation of the operator means 100, the'straps 54 and 56 will guide the movable stem 42 along a substantially straight line in an upward direction as shown in FIG. 1 while at the same time supporting the end 24 of the vacuum switch 20. At the end of disengaging movement of contacts 30 and 40, the movable connector will be in the position shown in FIG. 2. Movement of the rod member 104 to the left relative to the view of FIG. 1, pivots link member 106 counterclockwise and transmits closing force to the spring means 120 which in turn applies force to bushing 124 and lever arm 108. It may be noted that spring means 120 provides automatic adjustment of travel of stem 42 as contacts 40 and 30 are eroded during repeat operations.
While only the preferred embodiment of the invention has been shown herein, it will be realized that many modifications are feasible without departing from the spirit and scope of the invention. For example, the electrical switch with which the movable connector 2 is utilized may be any type of switch in which only a small movement which substantiates a straight line is required. It is accordingly intended that the scope of the invention is not to be limited by the specific embodiment disclosed.
1. In a support structure for an electrical switch having a fixed contact and a movable contact including a support arm and being movable along a substantially straight line into and out of engagement with the fixed contact, the combination comprising:
a terminal member;
a first group (plurality) of a flexible laminated electrically conducting plates having an outer end affixed to the support arm of the movable contact and an inner end affixed to said terminal member;
a second group (plurality) of flexible laminated electrically conducting plates spaced apart from the first group of conducting plates, said second group of conducting plates having an outer end affixed to the support arm of the movable contact with a portion of the support arm disposed between the outer ends of said first and second group of conducting plates and an inner end affixed to said terminal member with a portion of the terminal member disposed between the inner ends of said first and sec ond groups of conducting plates;
said movable contact and support arm being supported on said first and second groups of conducting plates with said first and second groups of conducting plates, said portion of the support arm and said portion of the terminal member forming a four-bar parallelogram, with the outer ends of each of said first and second groups of conducting plates being movable parallel to said substantially straight line; and
one of said first and second groups of conducting plates comprises an electrical connection to the movable contact.
2. In combination with a vacuum switch including first and second opposed ends, an enclosure containing a vacuum, flexible sealing means enclosing the enclosure adjacent the first end of the switch, fixed contact means extending out of the enclosure adjacent the second end of the switch, a movable contact including a stem extending out of the enclosure through the sealing means in sealed relationship therewith, said movable contact and stem being movable along a substantially straight line into and out of engagement with the fixed contact, a support structure wherein:
said second end of the vacuum switch is (rigidly) mounted on the support structure; and
said support structure includes a movable support,
said first end of the vacuum switch being mounted on the movable support, said movable support having a first strap comprising a plurality of flexible laminated plates and having an end affixed to the movable contact stem extending out of the enclosure, a second strap comprising a plurality of flexible laminated plates and having an end affixed to the movable contact stem extending out of the enclosure, with a portion of the movable contact stem disposed between the ends of the first and second straps, the other ends of said first and second straps being spaced apart such that said first and second straps and said portion of said movable contact stem comprises a four-bar parallelogram the ends of said straps being movable with said movable contact stem along a substantially straight line.
3. The combination according to claim 2 wherein said movable support is electrically connected to a fixed electrical terminal and is electrically conductive between the movable contact stem and the fixed electrical terminal.
4. The combination according to claim 3 wherein said first and second flexible straps are flexed toward the fixed contact means from their unflexed positions when the latter and the movable contact are in engagement and the laminated plates are resilient whereby the flexible straps counter-balance the atmospheric pressure againstthe vacuum within the enclosure tending to hold the movable contact in engagement with the fixed contact.
5. The combination according to claim 3 wherein one of said flexible laminated plates is electrically conductive.