US2848574A

US2848574A - Slow make and break switch

Info

Publication number: US2848574A
Application number: US452926A
Authority: US
Inventors: Hutt Philip; Edwin G Wilmot
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1954-08-30
Filing date: 1954-08-30
Publication date: 1958-08-19
Anticipated expiration: 1975-08-19

Description

P. HUTT ET AL SLOW MAKE AND BREAK SWITCH Filed Aug. 30, 1954 Aug. 19, 1958 2,848,574

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the narrow ledge 22. The resilient contact blade 32 then extends across the central depression 20 with the free end 37 underlying the contact portion 27 of the fixed contact 25. Looking at Figure 5, it should be appreciated that the strut members 28 and 34 of

contacts

25 and 30 respectively are held down by the insulating cover member 18 so that the contacts are fulcrumed on the ledges 22 and held in place by the notches 23 in the end walls of the switch housing.

In order to furnish a more positive holding action for the contacts in the housing, we have provided hold-down blocks 40 for preventing the contacts from shifting out of position under conditions of rough handling that might cause the contacts to drop. out of the housing through the openings 21. These blocks are best shown in Figure 9 and they are dimensioned to fill up most of the space in the housing between the struts 28 and 34 respectively and the adjacent end walls of the housing while extending from one side wall to the other within the housing. The central portion of the blocks 40 is cut out as at 41 in order to accommodate the mounting screw (not shown) that is used to fasten the switch to a supporting surface by engaging in the threaded aperture 16 in the cover plate ll. Similar cut-outs 42 and 43 are provided at either side of cut-out 41 to accommodate the shank of the terminal screws 17 as well as the upwardly extending tongue 33 of the movable contact 30.

As mentioned before, a pivoted trigger 15 is provided in the switch housing for actuating the movable switch blades 32. Trunnions 45 are formed on the sides of the trigger to lie within open bearings 46 formed in the opposite side walls of the body 10. The cover plates 11 and 18 overlie the trunnions 45 in the bearings 46 so that the trigger is confined to rotational movement in the bearings. Between the trunnions 4S, and at the lower end thereof, the trigger is provided with a rounded projection 47 that is adapted to bear on the upper sur face of the contact blades 32 of the movable contacts 3%). In the position of the trigger 15 in Figure 5, the projection 7 is engaged within the concave portion 36 of the blade 32. in this position the free end 37 of blade 32 is in engagement with the fixed contact portion 27 in order to complete the circuit. Thus, if the trigger 15 were pivoted to the left, the projection 4-7 would depress the blade 32 to open the circuit at that point. Since the second set of contacts is oppositely arranged from the first set mentioned above, it should be appreciated that when the trigger is moved the action of the one set of contacts will be opposite from the action of the remaining set so that this switch is in effect a singlepole double-throw switch.

A detent spring 50, as is best shown in Figures 4, and 7, is located centrally within the depression 20 of the housing to underlie the rounded projection 47 of the trigger 15. The function of this spring is to normally hold the trigger in either of its two extreme positions so that more than a casual force is needed to move the trigger 15 to its opposite position. This spring is made from a thin strip of resilient material such as beryllium copper and it has an arched central portion 51 as well as arched end portions 52 which are bifurcated to form a pair of downwardly extending legs 53 at both ends of the spring. Longitudinally spaced shelves 55 are formed adjacent the central depression 29 for supporting the spring 50 above the bottom wall of depression 20. Opposed abutments 56 are formed on the shelves 55 to be straddled by the bifurcated ends 52 of the spring 50 so that the spring is held in the housing by pressure against the opposite walls of the depression as well as by the cooperation of the abutments 56 with the bifurcations 52. The bifurcated ends 52 of the spring are of gradually diminishing cross-sectional area from the arched central portion to the ends of the spring. Thus, the spring is of substantially uniform strength. The spring is supported at both ends and the load is applied over the arched central portion. Both the width and thickness of the spring material are uniform so that the cross-sectional area is a maximum at the arched central portion that is designated as the area of loading. Hence, the outline of this spring in plan view is equivalent to two triangles in opposed relation with their apexes at the area where the load is supported by the spring. See Figure 4. Accordingly, the movement of the trigger 15 is resisted by the spring pressure of the detent spring 50 which must be overcome by depressing the arched portion 51 of the spring until the rounded projection 47 of the trigger is capable of riding over the arch 51 to operate the switch and make or break contact between the movable contacts 30 and the fixed contacts 25.

Consequently, having described our invention of a new and improved slow make and break electric switch, it will be readily apparent to those skilled in this art that we have devised a switch which is simple in design, reliable in operation and easy to assemble as well as readily adaptable to mass production methods of manufacture. While we have shown hold-down blocks for use with the movable and fixed contacts, it should be appreciated that under many conditions they may be eliminated as the cover plate may be relied upon to satisfactorily hold the contacts in the housing. Under conditions of severe handling and usage, it is preferable, however, to take advantage of the hold-down blocks so that the terminals are as reliable in operation as those which are permanently fixed to the switch housing by means of rivets or the like. Also, this switch can very easily be made into a three-way switch by merely placing a jumper strip across two adjacent terminals of the switch. Also, one of the sets of contacts may be reversed so that the movable contacts will open and close simultaneously to form a double-pole single-throw switch.

A possible modification of the detent spring would be to form the top of the arched central portion with a concavity so that the switch is changed to a three position switch with a variety of circuit combinations. As an example, the extreme end positions of the trigger could be the on positions for two different circuits while the middle position would serve as the o position. This change in the design of the spring, and consequently the action of the switch, could be made without altering the design of the other parts of the switch.

Modifications of this invention will occur to those skilled in this art and it is to be understood therefore that this invention is not limited to the particular embodiment disclosed but that it is intended to cover all modifications which are within the true spirit and scope of this invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. An electric switch comprising a recessed body member with a cover member for forming a hollow housing, the housing containing at least one fixed contact that is normally biased into engagement with a movable contact, each contact having a terminal end to which a lead wire may be connected, openings formed through the back Wall of said housing to accommodate the terminals of said contacts, the said terminals lying within the openings and being supported on a side ledge of their respective opening, upwardly inclined strut members formed on each contact to be in engagement with the underside of said cover so that each terminal is held seated on said ledges by the downward force supplied by the cover while the opposite edge of each of the terminals is held against an overlying stop member of the housing, and a trigger pivotally supported in said housing for holding the movable contact away from the fixed contact.

2. An electric switch as recited in claim 1 wherein there are a pair of fixed contacts and a pair of movable contacts normally biased into engagement therewith, and a pair of hold-down blocks seated over an adjacent pair of the terminals of said contacts while also being in engagement with the underside of the cover to assist in fixedly securing the terminals in the housing.

3. An electric switch comprising a hollow housing formed of a recessed body member and a cover with a pair of fixed contacts that are normally biased into engagement with a pair of movable contacts, openings formed through the back wall of said housing to accommodate the terminals of said contacts, each of the said terminals lying within an opening and being fulcrumed on a side ledge of their respective openings, while the opposite edge of each of the terminals underlies a ledge of said openings, at hold-down block seated over the terminals and being forced down by the cover to support the terminals in the openings, and a trigger pivotally supported in said base member for holding the movable contact away from the fixed contact.

4. An electric switch comprising a hollow housing having a fixed contact in cooperation with a movable contact, each contact having a terminal end fixed in the housing to which a lead wire may be connected, and a cover member for closing the said housing, a trigger pivotally mounted in the housing for moving the movable contact into and out of engagement with the fixed contact, and a detent spring located in the path of movement of said trigger to hold the trigger in one of several predetermined positions, the spring having an arched central portion as Well as arched end portions, said arched end portions being bifurcated along their entire length and having substantially vertical legs for holding the central portion away from the supporting surface, the said legs of the spring being braced between opposed walls in the housing with the legs at each end straddling an abutment formed as part of said walls so that the spring is supported against sidewise sliding movement in the housing.

5. An electric switch comprising a hollow housing, a

fixed contact and a movable contact blade located in the housing, a manually operated trigger pivotally mounted within the housing and engageable with the contact blade to move it away from the fixed contact, the trigger having a handle portion that extends outwardly through a top opening in the housing, and a pair of opposed walls in the housing, a detent spring braced between these opposed walls .and held in the path of movement of the trigger to hold the trigger in one of several predetermined positions, the spring having an arched central portion and arched end portions which are turned down vertically at the ends to form supporting legs, the spring being compressed slightly between the opposed walls to hold the spring in place, the said arched end portions being of gradually diminishing cross-sectional area from points adjacent the sides of the arched central portion to the nearest end of the spring.

6. An electric switch as recited in claim 5 wherein the said arched end portions are bifurcated to form a pair of vertical legs at both ends of the spring.

References Cited in the file of this patent UNITED STATES PATENTS 1,153,505 Levison Sept. 14, 1915 1,878,667 Both Sept. 20, 1932 1,992,432 Kilgour Feb. 26, 1935 2,253,968 Cook Aug. 26, 1941 2,377,134 Dietrich May 29, 1945 2,470,613 Gaynor May 17, 1949 2,500,181 Hubbell et al Mar. 14, 1950 2,626,335 Landin Jan. 20, 1953 2,705,785 Benander Apr. 5, 1955 FOREIGN PATENTS 110,450 Australia Apr. 23, 1940 562,631 Great Britain July 10, 1944