US2429813A

US2429813A - Snap action switch

Info

Publication number: US2429813A
Application number: US690622A
Authority: US
Inventors: George M Hausler
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1946-08-15
Filing date: 1946-08-15
Publication date: 1947-10-28
Anticipated expiration: 1964-10-28
Also published as: FR952100A

Description

G. M. HAUSLER 2,429,813

SNAP ACTION SWITCH Filed Aug. 15, 1946 Inventor George M. Hausler,

' His Attorney.

Patented Oct. 28, 1947 SNAP ACTION SWITCH George M. Hausler, Schenectady, N. Y., assignor to General Electrlccompany, 8- corporation of New York Application August 15, 1946, Serial No. 690,622

3 Claims. (Cl. 200-67) My invention relates to snap action electric switches and moreparticularly to snap acting switches especially adapted for slow actuation as by camming means and the like. The invention has for its object the provision of a new and novel switch of this character which is composed of a minimum number of parts and which is simple and inexpensive in construction without sacrifice of capacity, reliability, and durability.

In carrying out my invention, I utilize a switch member comprising a single unitary strip of spring material slotted to provide a tension member and a pair of spaced apart compression members in' opposing relation, the tension and compression members being connected at opposite outer ends of the strip. The juxtaposed ends of the compression members each pivotally en- It is a particular object of my invention to' provide a snap action switch of the above type carrying at one end of the spring strip a contact which is arranged for over-center movement through its position of zero pressure with respect to the fixed contact. Such a switch may be referred to as a no zerof switch. By this term it is meant that the switch is arranged to maintain upon the fixed contact a positive pressure until over-center movement of the spring strip is started. Once the over-center movement is started, it is self-completing without further movement of the actuating member, so that the movable contact passes through its position of zero pressure substantially instantaneously and can, under no circumstances; be stopped in a dead center position of zero pressure.

For a more complete understanding of my inventionand a further appreciation of itsobjects and advantages, reference should now be had to the following detailed specification'taken in conjunction with the accompanying drawing in which Fig. 1 is a side elevation of a cam-actuated snap action electric switch embodying my invention; Fig. 2 is a plan view of the switch shown Referring now-to thedrawings. I have shown my invention in one form as applied to a camactuated snap action switch comprising a base i preferably formed of a molded insulating compound, a supporting member 2 mounted in the base and a switch member 3 formed of. slotted spring material and carried by the supporting member 2. The'switch member 3 itself is a unitary fiat strip of spring material slotted longitudinally at 4 and 5 as best shown at Fig. 2 to provide a pair of outer tension arms 3a and 3b and a central pair of opposing compression arms 30 and 3d in spaced relation. 'The compression arms 30 and'3d are slightly deformable in compression and are formed by dividing the single central arm of the strip transversely in the region of. its center so that the inner ends of the arms 30 and 3d are in juxtaposed relation. vAt one end of the spring strip 3 is mounted a movable contact I0 and at the other end there is provided a projecting tip 3c.

The supporting member 2 comprises a substantially rigid metal strip fixedly mounted in thebase I and carrying at one end a pair of upright mounting posts 211 and 2b, as illustrated in. the drawing. The other end of the supporting member 2 protrudes from the opposite side of the base I to form a terminal connector I In the illustrated embodiment the mounting posts 2a and 2b are formed by cuttingout and turning up two central portions of the supporting member 2 itself. The posts 2a and 2b are V-shaped at their upper ends to provide pivot seats for the inner orjuxtaposed ends of .pression arms 30 and 3d in the plane of the spring strip 3, so that when the spring strip is mounted upon the posts the compression arms are de formed slightly to one side of the plane of the sprin strip and place the outer arms 3a and 3b under tension. Thus the mounting posts 2a and [217 have the form of cantilever beams and are slightly resilient in the manner of such beams, so that over-center movement of the spring strip with respect to the compression arms 30 and 3d may take place without appreciable buckling of the compression arms themselves.

For, the purpose of limiting movement of the movable contact I 0, carried at one end of the spring strip 3, I provide a pair of spaced apart fixed contacts H and I5 disposed upon opposite sides of the movable contact and serving as stop members. It will of course be appreciated that, if desired, only one of the stop members need be used as an electric contact. As shown in the drawing, the fixed contacts 14 and I5 are formed of strips of substantially rigid metal fixedly mounted in the base I and extending through the base to provide at the opposite side thereof terminal connectors Ida and IE1: respectively.

The switch member 3 is actuated by an L- shaped spring strip l8 mounted at one end in the base I and having its upturned end I 8a loosely connected to the tip 36 at that end of the spring strip 3 remote from the movable contact l0.

The lost motion connection between the spring strip 3 and the actuating member I8 comprises a wide slot IS in the upturned end l8a of the actuating member into which the tip 38 of the spring strip projects loosely. The slot I9 is considerably wider than the thickness of the tip 3e. The actuating member I8 is biased upwardly, as viewed in the drawing, into engagement with the rigid supporting member 2, thereby normally.to maintain the connected end of the spring strip 3 in its uppermost position above the pivot points of the compression members 30 and 3d. In this normal position, as illustrated at Fig. l, the movable contact 10 is also in its uppermost position and in engagement with the stationary contact I4.

The upturned end 18a of the actuating member I8 is arranged for cooperation with an operating cam 20, the cam 20 moving the actuating member and thus the connected end of the spring strip 3 downwardly, as viewed in the drawing, to actuate the switch.

From the foregoing understanding of the component parts of my invention, its mode of operation will be understood from the following brief description. It should be borne in mind that fundamentally the switch described above operates to move the movable contact In substantially instantaneously from a position of positive pressure on one fixed contact to a position of positive pressure on the other fixed contact, the position of zero pressure on the fixed contacts being a transient position.

It will be observed that as the cam 20 is rotated in a clockwise direction from the position shown at Fig. 1 to the position shown at Fig. 4, it slowly moves the actuating member l8 downwardly. The actuating member carries with it the connected end of the spring strip 3. When the cam and actuating member reach the position shown at Fig. 3, the righthand end of the spring strip 3 has been moved to such a position that the spring strip is about to move over-center with respect to the compression arm 3d. In this position, however, the spring strip has not yet reached its over-center position with respect to the compression arm 30, so that a positive pressure is still exerted by the arm 30 to hold the movable contact III in engagement with the upper fixed contact [4. When the right side of the spring strip 3 moves over-center with respect to the compression arm 3d, upon a very slight further movement of the cam from the position shown at Fig. 3, the right end of the spring'strip moves downwardly in the slot IS without further movement of the cam 20 or the actuating member 18. During this movement in taking up the lost motion between the spring strip and the actuating member, the spring strip ismoved by its own action over-center with respect to thecompression arm 3c at the other end of the spring strip. When this second over-center action occurs, the movable contact I0 is moved with a snap action from its upper position shown at Figs. 1 and 3 to its lower position shown at Fig. 4. The over-center movement of the contact carrying end of the spring strip moves the plane of the tension members 311 and 3b below the pivot point of the compression arm 30, so that a positive pressure is immediately applied between the movable contact I!) and the fixed contact IS, without further downward movement of the actuating member [8. Further movement of the started. As soon as such over-center movement occurs, it automatically effects over-center movement of the contact carrying end of the spring strip without further movement of the actuating member, so that the movable contact passes substantially instantaneously from a position of positive pressure against one fixed contact to a position of positive pressure against the other fixed contact. It will be understood that a similar action occurs upon reverse movement.

A snap action switch of the above typeembodying my invention may be built in very small sizes and with a remarkably high interrupting capacity for both alternating and direct current in comparison to its physical dimensions. The switch is also suitable for precision work since movement of the actuating member required to effect circuit making or circuit breaking movement of the contacts is quite small and remains substantially constant. For example, in a typical switching device in which the switch member of spring material is approximately 1%" in length, the actuating movement is approximately 1 6" and was found to be substantially invariable after many thousands'of operations.

While I have shown and described only a preferred embodiment of my invention by way of i1- lustration, many modifications will occur to those skilled in the art, and I therefore wish to have it understood that I intend in the appended claims to cover all such modifications as fall within the true spirit and scope of my invention.

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

1. A snap action electric switch comprising an integral strip of spring material slotted longitudinally to form a plurality of substantially parallel resilient arms connected together at opposite outer ends of said strip, one of said arms being divided transversely intermediate its ends to provide a pair of spaced apart opposing compression members having their ends in juxtaposition, a fixed supporting member interposed between and having pivotally mounted thereon the juxtaposed ends of said compression members thereby to support said spring strip, a movable contact mounted upon one end of said spring strip, a pair of stop members including a cooperating fixed contact positioned in spaced relation on opposite sides of said one end of said spring strip, and lost motion actuating means connected to the other end of said spring strip for moving said other end over-center with respect to the adjacent compression member, said over-center movement 2,42aeia moving said one end of said spring strip over-center, thereby to move said movable contact between said stop members with a snap action.

2. A snap action electric switch comprising an integral strip of spring material slotted longitudinally to form a plurality of substantially parallel resilient arms connected together at opposite outer ends oi said strip, one of said arms being divided transversely intermediate its ends to provide a pair of spaced-apart opposing compression members having their ends in juxtaposition,

a fixed supporting member interposed between and having pivotally mounted thereon the juxtaposed ends of said compression members thereby to support said spring strip, a movable contact mounted upon one end 01' said spring strip, a pair of stop members including a cooperating fixed contact positioned in spaced relation on opposite sides of said one end of said spring strip, a movable actuating member, and lost motion means connecting said actuating member to move the other end of said strip over-center with respect to the adjacent compression member, said overcenter movement carrying said spring strip overcenter with respect to the other compression member, thereby to move said movable contact between said stops with a snap action.

3. A snap action electric switch comprising an integral strip of spring material slotted longitudinally to form a plurality of substantially par- 6 allel resilient arms connected together at opposite outer ends of said strip, one or said arms being divided transversely intermediate its ends to provide a pair of spaced apart opposing compression members having their ends in juxtaposition, a fixed supporting member interposed between and having lvotally mounted thereon the juxtaposed ends of said compression members thereby to support said spring strip, said supporting member being wider between said juxtaposed ends than the normal space between said ends in the plane of said spring strip, a movable contact mounted upon one end of said spring strip, a pair of stop members including acooperating fixed contact positioned in spaced relation on 0pposite sides of said one end of said spring strip, a movable actuating member, a lost motion connection between said actuating member and the other end of said strip, means biasing said actuating member to a predetermined normal position, and camming means arranged to move said actuating member slowly in a direction to move said other end of said strip over-center with re spect to the adjacent compression member, said strip upon over-center movement taking up said lost motion and moving over-center with respect to the other of said compression members, thereby to move said movable contact between said stop members with a snap action.

GEORGE M. HAUSLER.