US2769064A - Electric switch - Google Patents

Description

Oct. 30, 1956 R. N. ROWE ELECTRIC SWITCH Filed Sept. 22, 1953 United States Patent ELECTRIC SWITCH Raymond N. Rowe, Plainville, Conn., assignor to General Electric Company, a corporation of New York Application September 22, 1953, Serial No. 381,654

13 Claims. (Cl. 200-146 The present invention relates to improved electric switches and more particularly to improved contact assembles for electric switches including both main and areing contacts.

Electric switches employing a U-shaped movable contact have been widely used. Applicants prior Patent 2,494,315 discloses a small, compact switch unit structure of simple and dependable construction which has had Wide acceptance in industrial applications. As the current rating of switches of this type increases, the contact pressure required for satisfactory operation increases to the point where the force required for moving the contact into and out of engagement with the stationary contacts is excessive. It is an important object of the present invention to provide an improved movable contact assembly which reduces the force required for actuation of the contact without correspondingly reducing the contact pressure.

It is another object of the invention to provide a new and improved electric switch with particular reference to the movable and stationary contact assemblies.

A further object of the invention is to provide a new and improved movable contact assembly including both main and arcing contacts.

Further objects and advantages of my invention will become apparent as the following description proceeds, reference being had to the accompanying drawing, and its scope will be pointed out in the appended claims. In the drawing, Fig. 1 is a perspective view of an electric switch embodying my invention; Fig. 2 is an exploded view in perspective of the movable contact assembly of Fig. 1; Fig. 3 is a perspective view of one of the stationary arcing contact assemblies of the switch shown in Fig. 1; Fig. 4 is an elevational view partially in section of the electric switch shown in Fig. l; and Fig. 5 is a schematic diagram of two switch units embodying my invention connected with the main contacts thereof in parallel and with the arcing contact in series.

Referring now to the drawing, the electric switch forming the illustrated embodiment of my invention includes a generally hollow rectangular box-like frame 1 which supports a pair of stationary contacts 3 and 4, a movable contact assembly 5, and a pair of stationary arcing contact assemblies 6 and 7.

The frame includes a pair of side plates 8 and 9 of sheet insulating material which are secured together in spaced parallel relation by a pair of metal channels 10 and 11. As illustrated, the insulating plates 8 and 9 are secured to the flanges of the channel members 10 and 11 by rivets 12. The stationary contacts 3 and 4 include integral lugs 13 at opposite ends thereof which extend through suitable openings in the side plates 8 and 9 to help position the stationary contacts and to space side plates 8 and 9. The assembly, including the frame 1, is secured to an insulating base 14, to which are secured the line and load conductors 15 and 16, by means of screws 17 which extend through integral flanges 18 formed on the channels 10 and 11 and through terminal portions 19 formed integrally with the stationary contacts 3 and 4 and through the end portions 20 of the line and load conductors 15 and 16, respectively. In order to facilitate removal of the frame from the base, the openings in the flanges 18 and the terminals 19 are open-ended.

The space within the frame 1 is divided into three switching compartments, each having insulating side walls, by means of insulating plates 21 and 22 which extend in spaced and parallel relation with respect to the channels 10 and 11 and which are provided with integral lugs 23 extending from opposite ends thereof and received in suitable openings in the side plates 8 and 9. Sheets of insulating material 24 and 25 are secured to the inner surfaces of the channels 10 and 11 to complete the insulating walls of the compartments formed by the plates 21 and 22.

The stationary arcing contacts are mounted in subassemblies which are positioned within the compartments of the frame 1 provided by the insulating plates 21 and 22. Each of the assemblies 6 and 7 are of identical construction and only one will be described. Referring particularly to Fig. 3 of the drawing, the stationary arcing contact assembly includes a pair of elongated strap conductors 26 and 27 which are supported in parallel opposed relation from an insulating structure including a battle 28 and spacer members 29a, 29b, 29c and 29d. Side plates 30 and 31 of insulating material complete the sub-assembly which is held together by suitable rivets 32. As illustrated, baffle plate 28 is provided with integral extensions 33 which pass through the side plates 8 and 9 to support the stationary arcing contact assembly in the frame. These extensions also separate the terminal portions of the stationary arcing contacts from one another on the outside of the frame. As will become more apparent as the description proceeds, the baffle member 28 in cooperation with a recessed insulating member 34 divides the stationary arcing contact assembly into two compartments for reception of the arms of the U-shaped arcing contact 35 and interrupts any direct arc path between the stationary arcing contacts 26 and 27.

The movable contact assembly which forms an important aspect of my invention is best illustrated in Figs. 2 and 4. The assembly includes a pair of generally U-shaped laminated contact members 36 and 37 having active contact portions 38 on the outer surface of the free ends thereof. These surfaces are biased outwardly by compression springs 39 which function in cooperation with the inherent resilience of the contacts to provide the contact pressure. In order to actuate the contacts, they are supported in side-by-side relation within a contact carrier which, in the embodiment illustrated, is in the form of a U-shaped sheet metal frame 40 having the opposed arms of the frame covering the open sides of the U-shaped contacts 37. The contacts are retained within the frame by means of parallel pins 41 extending between the opposed arms of the frame on the outside of the opposed arms of the contacts 37. Preferably, pins 41 are surrounded by rollers 42. As illustrated, the contacts 37 are indented inwardly to provide cam surfaces 43 and 44 on opposite sides of the rollers 42. It will be apparent that as a force is applied to the carrier 40 in a direction to move the contacts 37 into or out of engagement with the stationary contacts 3 and 4 (see Fig. 4), the reaction of the stationary contacts on the movable contact will tend to move it relative to the carrier and relative to rollers 42 which act as cam followers on the cam surfaces 43 and 44. As the rollers move along cam surfaces 43 and 44 on circuit closing and circuit opening movements, respectively, they force the contact surfaces inwardly. This action of the rollers on the cam surfaces reduces the contact pressure during circuit making and circuit breaking .one from the, other.

switch units.

operation and substantially reduces the force required for movement of the movable contact assembly.

The movable contact assembly includes, in addition .to the parts already described, an insulatingplate 45 and usual application of the switch, the rod is as shown in dotted lines at 5:1} in Pig. 4-. The carrier is also provided with integral extensions 51 which engage the ends of the plates 8 and 9 to form limit stops for the movable contact assembly. The U-shaped member 46 is also provided with integral lateral extensions 5'2 which slide upon tracks at opposite sides of the frame provided by angle irons 54 secured to the inner walls of the insula ting plates 8 and As best seen from Fig. 4, the arcing contacts 35 and the stationary arcing contacts 26 and27 are positioned in the assembly with respect to the main contacts so that the arcing contacts engage before the main contacts on circuit closing operation and disengage after the main contact on circuit opening operation, thus insuring that arcing occurs a: the arcing contact and rendering it feasible to substantially reduce the contact pressure at the main contacts during movement of these contacts into or out of engagement with the main stationary contacts 3 and 4. Without this arrangement of the arcing contacts, any reduction in contact pressure at the main contacts would tend to cause excessive arcing and resultant burning at these contacts.

From the foregoing description, it will be apparent that each of the arcing contacts 26 and 27 of the stationary arcing contact assembly 6 and '7 are completely insulated As illustrated in Fig. l, the stationary arcing contacts of both the assemblies 6 and 7 are connected in series between the line and load conductors 1S and 16 by conducting straps 55, 56 and 57. It is an advantage of this independent mounting of the stationary arcing contacts that all of the gaps provided by these contacts may beconnected in series across, the main contacts when a plurality of switch units are connected with their main contacts in parallel. ,In Fig. 5 of the drawing,

I have shown such a connection for two switch units. As there illustrated, the line conductors are connected together by a conductor 58 and the load conductors 16 connected together by conductor 59. This connects the main contacts in parallel. The arcing contacts of the stationary arcing contact assemblies are all connected in series by removing the conductor 57' from one of the switch units and the conductor 55 from the other of the The lower contact 27' of the arcing contact assembly '7' of the first unit is then connected to the upper contact 26' of the arcing contact assembly 6 of the other switch by a conductor 61 ltwill be apparent from a consideration of the diagram of Fig. 5 that the four gaps provided by the stationary arcing contactassemblies are then connected in series and across the main contacts 3', 4 of both switch units.

While there has been shown and described a particular embodiment of the invention, it will be obvious to those skilled in the art that changes and modifications may be ,made without departing from the invention, and that it "Patent of the United States is:

l.- A movable contact assembly for bridging a pair of generally parallel stationary contacts including a U-shaped bridging contact for insertion between said stationary contacts by movement in a given direction, a support for carrying said bridging contact, the opposed arms of said bridging contact having cam surfaces thereon extending at an angle to said direction, and means fixed to said support and engaging said cam surfaces to move the free ends of said bridging contact'transversely with respect to said direction in response to force applied to said support to move said bridging contact into or out of engagement with said stationary contacts, said means including pins extending between the opposed arms of said' U-shaped frame on the'outside of 'the arms of said bridging contacts and sleeves rotatably supported on said pins.

2. A movable contact assembly for bridging a pair of generally parallel stationary contacts including a U-shaped bridging contact for insertion between said stationary contacts by movement in a given direction, a U-shaped frame for i i s a d b in C nt c t prip sed arms of said bridging contacth'aving'ca'msurfaces thereon extending at an angle to said direction, and means fixed to said frame and engaging said cam surfaces to move the free ends of said bridging contact transversely with respect to said direction in response to force applied to said frame to move said bridging contact into or out of engagement with said stationary contacts, said means in cluding pins extending between the opposed arms of said U-shaped frame on the outside of the arms of said bridging contacts and sleeves rotatably supported on said pins.

3. A movable contact assembly for bridging a pair of generally parallel stationary contacts including a U-shaped bridging contact for insertion between said stationary contacts by movement in a given direction, a U-shaped frame for carrying said bridging contact, the opposed arms of said bridging contact having cam surfaces thereon extending at an angle to said direction, and means fixed to said frame and engaging said cam surfaces to move the free ends of said bridging contact transversely with respect to said direction in response to force applied to said frame to move said bridging contact into or out of engagement with said stationary contacts, an insulating support secured to said frame and extending from opposite sides thereof and a pair of U-shaped movable arcing contacts carried by said support. c

4. A switch unit comprising a pair of side plates of sheet insulating material, means securing said plates in spaced parallel relation, a pair of main stationary contacts extending between said plates, a pair of arcing contact assemblies extending between said plates and each including a pair of parallel contacts, said assemblies being positioned on opposite sides of said main contact, a movable contact assembly including a U-shaped frame, a Ll-shaped main contact supported from said frame and a pair of U-shaped arcing contacts supported on either side of said U-shaped main contact and in insulated relation with respect thereto and with respect to one another, and means mounting said movable contact assembly for sliding movement with respect to said plates.

5 A switch unit comprising a pair of side plates of sheet insulating material, a pair of main stationary contacts extending in parallel relation between said plates and each including a terminal portion extending through one of said plates, a pair of arcing contact assemblies extending between said plates on opposite sides of said main contacts and each including a pair of spaced parallelcontacts including portions extending through said plates, and conductors external to said plates connecting the contacts ,of said arcing contact assemblies in series and across said main contacts.

6. In an electric switch, a pair of stationary contacts, a pair of electrically connected movable contacts mounted on a common support for movement as a unit between on and off positions, resilientmeans for urging said c0ntacts"in said "on ""positi0n with a predetermined amount of pressure, movable operating means for moving said movable contacts along a predetermined path between said on and off positions, said operating means including means movable relative to said movable contacts along said predetermined path when said movable contacts are moved from said on and said off position tending to move said movable contacts transversely relative to said predetermined path in a direction away from said stationary contacts against the bias of said resilient means to decrease said contact pressure.

7. In an electric switch, a pair of confronting stationary contacts, a generally U-shaped movable contact member having contact surfaces adjacent the free ends thereof receivable between said stationary contacts, resilient means resiliently opposing movement of said contact surfaces toward each other, movable operating means for moving said contact member into and out of engagement with said stationary contacts, guide means for restricting movement of said contact member to movement along a predetermined path, said operating means being movable relative to said movable contacts along said predetermined path and applying force to said U-shaped member on opposite sides thereof and at an angle to said predetermined path to simultaneously urge said contact surfaces toward each other against the bias of said resilient means and to move said U-shaped contact member along said predetermined path.

8. In an electric switch, a pair of confronting stationary contacts, a movable contact member having a pair of elongated generally parallel contact carrying arms, movable operating means for moving said movable contact arms between on and off contact positions with respect to said stationary contacts along a predetermined path, a cam surface on each of said arms, cam follower members movable by said operating member relative to said movable contact and cooperable with said cam surfaces to urge said arms of said contact member toward each other while simultaneously urging said contact member along said predetermined path, and resilient means yieldingly opposing such movement of said contacts toward each other.

9. In an electric switch, a pair of confronting stationary contacts, a generally U-shaped resilient movable contact member having two generally parallel arms, contact surfaces carried by the outer ends of said arms and receivable between said stationary contacts, opposite intermediate portions of said arms being deformed toward each other to provide indentations therein each comprising two converging cam surfaces, movable operating means for operating said U-shaped resilient contact member comprising an operating member having portions thereof positioned in said recesses and slidable along said cam surfaces during operation of said switch.

10. An electric switch contact comprising a generally U-shaped member comprising two generally parallel arms of flat strip metal having their major surfaces generally parallel to each other and to the axis of the bend of said U, contact surfaces carried by said arms at the outer ends thereof and facing outwardly from said U, resilient means yieldingly opposing movement of said contact surfaces toward each other, said arms having opposed intermediate portions thereof deformed toward the inner portion of said U to provide an indentation in each of said arms comprising two converging cam surfaces and movable operating means for operating said U-shaped member comprising an operating member having portions thereof positioned in said indentations and slidable along said cam surfaces during operation of said switch.

11. A switch unit comprising a pair of stationary main contacts, a pair of stationary arcing contacts, a movable contact operator, a generally U-shaped main contact connected to said contact operator, a generally U-shaped arcing contact connected to said contact operator for movement with said main contact between on and off positions, supporting and insulating means for said stationary and movable contacts comprising electrically insulating partitions providing separate compartments for said main and arcing contacts, and means carried by said supporting and insulating means for supporting and guiding said contact operator.

12. The switch unit as set forth in claim 11 wherein each of said stationary main contacts and said stationary arcing contacts is provided with individual terminal connecting means accessible from the exterior of said enclosing means.

13. A switch unit comprising a pair of stationary main contacts, a pair of arcing contact assemblies positioned on opposite sides of said pair of main contacts and each including a pair of stationary arcing contacts, a movable contact assembly comprising a movable contact carrier, 21 generally U-shaped main contact supported on said carrier and a pair of generally U-shaped arcing contacts supported on said carrier at either side of said pair of main contacts for movement therewith between on and off positions and in insulated relation thereto and with respect to one another, supporting and enclosing means for all of said stationary and movable contacts comprising separate compartments for each of said main and arcing contact assemblies, and individual terminal connecting means for each of said stationary main contacts and said stationary arcing contacts, said individual terminal connecting means each being accessible from the exterior of said enclosing means.

References Cited in the file of this patent UNITED STATES PATENTS 667,764 Bruce Feb. 12, 1901 1,688,747 Paul Oct. 23, 1928 2,030,691 Eaton Feb. 11, 1936 2,447,353 Merrill Aug. 17, 1948 2,494,315 Rowe Jan. 10, 1950

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