Abstract:
An electrical power distribution switch includes an operating member that carries a first plurality of spaced switch contacts and a support arrangement for pivotally supporting the operating member. One of the ends of the operating member includes a circumferential bearing surface. The support arrangement cooperates with the circumferential bearing surface. In a preferred arrangement, electrical connections to the spaced switch contacts carried by the operating member are oriented to provide clearance to cable terminations while also simplifying the electrical connection components.

Description:
This application claims the benefit of U.S. Provisional Application No. 60/128,710 filed on Apr. 8, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to power distribution switches and more particularly to an improved operating member and support structure for pivotally mounted switch blades. 
     2. Description of Related Art 
     Various switches and operating mechanisms are shown in the following U.S. Pat. Nos.: 3,563,102; 3,676,629; 3,845,433; 4,293,834; 4,484,046; 4,761,524, 4,806,716, 5,140,117; 5,224,590; 5,504,293 and 5,772,009. For example, U.S. Pat. No. 3,563,102 discloses a quick-make quick-break mechanism for operating a switch between open and closed positions. While these switches and operating mechanisms may be generally suitable for their intended use, it is always desirable to provide improved components and operating characteristics. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is a principal object of the present invention to provide an improved operating member and support structure for pivotally mounted switch blades. 
     This and other objects of the present invention are achieved by an operating member that carries a first plurality of spaced switch contacts and a support arrangement for pivotally supporting the operating member. One of the ends of the operating member includes a circumferential bearing surface. The support arrangement cooperates with the circumferential bearing surface. In a preferred arrangement, electrical connections to the spaced switch contacts carried by the operating member are oriented to provide clearance to cable terminations while also simplifying the electrical connection components. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the specification taken in conjunction with the accompanying drawing in which: 
     FIG. 1 is a front elevational view of a switch in accordance with the principles of the present invention; 
     FIG. 2 is a view, partly in section, taken generally along the line  2 — 2  of FIG. 1; 
     FIG. 3 is an elevational view of a bearing for an operating member of the switch of FIGS. 1 and 2; 
     FIG. 4 is an enlarged view, partly in section, of portions of the switch of FIG. 1 illustrating the support of the operating member of the switch of FIGS. 1 and 2; and 
     FIG. 5 is a right-side elevational view of a support bracket for the bearing and operating member of the switch of FIGS.  1 - 4 . 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIGS. 1 and 2, a power distribution switch  10  in accordance with the present invention includes multiple switch poles, e.g. three switch-pole assemblies  12 ,  14  and  16  as illustrated in the specific embodiment of FIG.  1 . In this specific illustrative embodiment, the three switch-pole assemblies  12 ,  14  and  16  are operable between open and closed positions via pivotally mounted switch blades  18 ,  20  and  22  respectively, the closed position being shown in FIGS. 1 and 2, the open position shown in phantom in FIG. 2 at  18 ′. The switch blades  18 ,  20  and  22  are carried by an operating member  30  that is mounted for pivotal movement about an axis  32  that is substantially horizontal in the illustrative arrangement. Each of the switch-pole assemblies  12 ,  14  and  16  includes a stationary contact assembly  36  having arc-extinguishing capabilities in the specific embodiment where the switch  10  is a load-interrupting switch. The stationary contact assemblies  36  are each supported by an insulator  38  affixed to a frame  40  of the switch  10 . The switch blades  18 ,  20  and  22  are each electrically connected to a respective lower contact terminal  42  via a sliding contact arrangement provided by lower contact assemblies  43  (FIG. 2) carried by the lower contact terminal  42 . The sliding contact feature is also commonly referred to as a wiping contact. The lower contact terminals  42  are supported with respect to the frame  40  at planar portions  45  (FIG. 2) via insulators  44 , for example, lower contact terminals  42   a, b  and  c  supported by respective insulators  44   a, b  and  c.    
     The operating member  30  is rotated via a linkage  50  that connects an operating shaft  52  of the operating member  30  to be driven by an operating mechanism  54 . The operating mechanism  54  is a stored energy device that is operated by a handle  56 . The operating member  30  is rotatably mounted at a first end by the operating shaft  52  within a bearing  58 . The opposite end of the operating member  30  is pivotally supported at  60  via a support bracket  62  that is affixed to the support insulator  44 . In a specific embodiment, the support bracket  62  is conductive. Thus, in operation, the support bracket  62  is energized at the same potential as the lower contact terminal  42 . 
     With additional reference to FIGS. 3-5, the operating member  30  includes a cylindrical bearing surface  64  (FIGS. 1 and 4) that is received within a bearing  66  carried within a circular receiving opening  68  (FIG. 5) of the support bracket  62 . The bearing  66  is of split ring construction (FIG. 3) and is retained within a circular receiving opening  68  of the support bracket  62  via the cooperation between a groove  70  and shoulders  72 ,  74  on the perimeter of the bearing  66  and the rim  76  of the receiving opening  68  of the support bracket  62 . In this way, the bearing  66  is installed within the rim  76  of the receiving opening  68  and the inserted operating member  30  in the vicinity of the cylindrical bearing surface  64  locks or retains the operating member  30  and the bearing  66  within the support bracket  62 . In a specific embodiment, the bearing  66  is fabricated from molybdenum-impregnated nylon, while the operating member  30  is fabricated from cycloaliphatic epoxy resin. This combination has been found suitable to accomplish the high speed operation and support of the operating member  30  via the quick-make, quick-break operating mechanism  54  of the switch  10 . In accordance with this configuration, it has been found possible to achieve a low ratio between the axial length  71  and the diameter  73  of the bearing  66 , e.g. on the order of 1:6 as illustrated in FIGS. 3 and 4. This low ratio is useful to minimize the axial lengths of the bearing  66  and the cylindrical bearing surface  64 , the overall length of the operating member  30 , and the distance by which the operating member  30  and the support bracket  62  extend beyond the support insulator  44   a , with resultant economies of space and component sizes. 
     It has been found desirable to mount the contact assemblies  43  so as to be aligned along the path between the center  32  of the operating member  30  and the base of the support insulators  44 . In that way any movement of the insulators that may be caused by extreme loading results in movement of the contact assemblies  43  more nearly along the circumferential surface contact of the switch blades  18 ,  20  and  22 . For example, different mounting orientations result in movement of the contact assemblies in a direction that tends to separate the contact assemblies from the switch blades  18 ,  20  and  22 . In accordance with additional aspects of the present invention, the insulators  44  supporting the operating member  30  are oriented such that their longitudinal axes, e.g.  80 , are aligned with respect to the radial axis  82  of the operating member  30  as seen in FIG. 2 but not directly below the operating member  30 . This orientation provides for preservation of space in the cable termination area, generally referred to at  84  beneath and to the rear of the lower contact terminals  42 , while also simplifying the mounting of the lower contact terminals  42  and the lower contact assemblies  43  to the support insulators  44 . Specifically, this permits mounting of the planar portions  45  of the lower contact terminals  42  and the lower contact assemblies  43  directly to an upper planar surface  86  of the support insulators  44  which simplifies the shape and fabrication of the lower contact terminals  42  and the lower contact assemblies  43  and avoids the need for additional parts to mount these components. As seen in FIG. 2, a lower mounting member  88  of the frame  40 , to which the lower planar surfaces  90  of the insulators  44  are mounted, is tilted or inclined with respect to the generally planar configuration of the switch  10  and the frame  40  and an upper mounting member  92  of the frame  40  to which the upper support insulators  38  are mounted. The generally planar configuration of the switch  10  and the frame  40  are typically arranged vertically for application in metal-enclosed gear. 
     While there have been illustrated and described various embodiments of the present invention, it will be apparent that various changes and modifications will occur to those skilled in the art. Accordingly, it is intended in the appended claims to cover all such changes and modifications that fall within the true spirit and scope of the present invention.