US2697145A

US2697145A - Snap action device

Info

Publication number: US2697145A
Application number: US249272A
Authority: US
Inventors: Winet Hans
Original assignee: Landis and Gyr AG
Current assignee: Landis and Gyr AG
Priority date: 1951-04-26
Filing date: 1951-10-02
Publication date: 1954-12-14
Anticipated expiration: 1971-12-14
Also published as: FR1053354A; CH289820A; GB708326A; DE1024608B; NL73486C

Description

Dec. 14, 1954 H. wlNET SNAP ACTION DEVICE Filed Oct. 2, 1951 /N v /v TOR HANS W/NET ATTORNEYS.

United States Patent SNAP ACTION DEVICE Hans Winet, Zurich-Wollishofcn,. Switzerland; assignor to Landisc Gyr, A. G., a body corporateof'switzerland Application ctober 2, 1951, Serial No. 249,272

Claims priority, application Switzerland April 26, 1951 7 Claims. ((31.200-67) The present invention is a snap action device particularly as-adapted to-be usedin electric switches.

Objects and advantages of the invention will beset forth inpart hereinafter and inpart will be obvious herefrom, ormay be learned by'practice' with the invention, the same being realized andattained by means: of the inst-rurnentalitiespointedoutin the appended claims:

The invention consists in the novel parts, constructions, arrangements, combinations and improvements herein shownv and' described.

An object of the invention is to provide a novel snap action device which can be made from a single blank cheaply and easily.

A further object of the invention is to provide a novel snap action device which can readily be adapted to be used with electric switches, and similar devices.

The accompanying drawings, referred to herein and constituting a part hereof, illustrate one embodiment of the invention, and together with the description, serve to explain the principles of the invention.

In the drawings:

Fig. l is a front sectional view showing the novel snap action device mounted in a tumbler switch with the snap action device shown in its normal position of rest.

Figs. 2-4 are front elevational views of the snap action device in a tumbler switch in various operative positions. Fig. 4 illustrates the abnormal position in contrast to Fig. l, the normal or resting position.

Fig. 5 is a top plan view of the novel snap action device.

Fig. 6 is a sectional view of the embodiment shown in Fig. 5, as viewed along line 66.

Fig. 7 is a side elevational view of the embodiment shown in Fig. 5.

Figs. 8 to are diagrammatic representations of the trip spring in the operative positions illustrated in Figs. l-3.

As shown in Fig. 1, the snap action device is mounted in a tumbler switch, said tumbler switch consisting of a mounting plate 1 made of insulating material, a contact 2, a housing cover 3, a second contact 4 and a switching member 5. The switching member 5 is operatively connected to the novel snap action device. The snap action device is made from a single blank and is in the form of a spring. The snap action device or spring is positioned in the housing formed by the mounting plate 1 and the cover 3, said spring locally fixed at two points a, a to a base piece 6, the base piece 6 having the shape of a U (Figs. l-4) formed within a plane (as shown by the dotted lines of Fig. 7). The spring may be fixed, for example, by welding with the U-shaped plane plate 6 having pro ections 8-8 on which washers 9, 9' are mounted. The snap action device or spring consists of two longitudinal stiffened

members

10 and 11 connected integrally by

end members

12 and 13. End member 12 has an aperture 14 adapted to receive a contact 15. The

members

10 and 11 are stiffened by means of bendingover operations effected on the outwardly directed edges of said parts to form

lips

10a and 11a. Elastically deformable U-shaped

sections

16 and 17 are formed near the right end of stiffening

members

10 and 11 by merely bending said members in the shape of a U out of the plane of said stiffened members. From the left station ary point a, there passes to the right another stittfened member 18, the stiffening of which is brought about by stamping it in the shape of a trough 19. Two

compression spring parts

20 and 21 are connected at their left "ice 2 end to end member 12 a nrl at their: right end to stiffened member 18. In making the-spring, the-spring is stamped out of an elastic pieceof sheet such: as bronze sheet. "Fl-remembers 20 and 2 1' must be bent'upwardly when the: spring istmount'ed in the plate: 6 so that? said

members

20 and 21 can serve afterwards as compression springs.

Figs. 8 to 10', the diagrammatic illustrations of the spring, have been in'cl-uded in: order to show the forces actingon the spring when in use. In the position of. rest shown in Fig. 8, a turning moment M1 acts in a; counterclockwise direction on the stiffened

members

10 and 1 1:" which are connected at their left end by the end member 12 carrying: the Contact" 15, which turning moment produces a comparatively large. pressure between contacts 2- and 15. If a definite actuating pressurev Do acts on the stiffened member 18, said member 18! is swung in a clockwise direction. This in turn causes-the right end of member 18 to drop thu'sdecreasing the turn-- ing moment M-i. As can be seen in Fig. 9, after the" right end of stiffened member 1 8has dropped to a certain' point, the compressive force of the members 28 and 21 now acts in: the plane of the: stiffened members. It) and 1 1. slight additional increase of the. actuating pressure Db tb lD1 produces: a small shift of the stiffened member 18 which causes the spring to trip. As can be seen in Fig. 10, the turning moment now acts in the clockwise direction on the

stiflfened members

10 and 11. In order to return the switch to its original contact position, the pressure on the switching member 5 must be reduced from D1 to (D2D1). By moving the

parts

2 and 4, it is also possible to cause the spring to trip by means of an actuating pressure in the opposite direction.

As can be seen from the relative shapes of

members

16 and 17 in Figs. l-4, the forces of different magnitude acting in the longitudinal direction of

tension members

10, 11 cause the elastically

deformable members

16 and 17 to change their shape so that contact 15 executes a relative motion in the horizontal direction. This has the double feature in that, first, a self-cleaning effect of the contact surfaces is obtained and secondly, contact weldings that have occurred are removed.

The snap action device or spring of this invention has many other desirable features. Since no knife edges are used as part of the device, the spring remains practically free of friction since no friction surfaces are present and only variations of internal strain appear at the bearing points. Changes in stress of the spring in consequence of wear of bearings are therefore out of question. The flexure of

compression members

20 and 21 is not critical, as according to Euler the power of reaction of a leaf spring subjected to buckling stress remains almost constant for small flexures within the elastic limit, in contradistinction to the conditions obtained with regard to helical springs. This olfers the advantage that the making and mounting of the spring is greatly facilitated as no narrow tolerances must be observed. For the same reasons, no adjusting members for the pressure of the spring are necessary. The electric current carrying capacity of the current carrying spring is comparatively great as no unsafe points in knife edge bearings need be taken into consideration.

As mentioned previously the spring may be stamped from a single blank which makes its production very cheap. No support members for

compression members

20 and 21 are required and it is obvious that it is relatively simple to mount the spring when in use.

The invention in its broader aspects is not limited to the specific combinations and improvements described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages.

I claim: I

1. A snap action device made from a single blank of metal comprising two symmetrically arranged spring members acting as compression springs, said members being disposed between two stiffened members, said stiffened members being stationary at one end and connected to each other at the other end by means of a contact carrying member, each of said stiffened members having an elastically deformable section, and a third stiffened member located, between said symmetrically arranged spring members and being stationary at the opposite end at which said above two stitfened members are stationary, said third stiffened member being free at its other end and serving as an actuating member.

2. A snap action device as defined in claim 1, in which the elastically deformable section of the two stiffened members is U-shaped section bent out of the plane of the snap action device.

3. A snap action device as defined in claim 1 in which the stationary ends of the three stiffened members are supported on the outer legs of a U-shaped plane base piece.

4. A snap action device as defined in claim 3 in which the stationary ends of the three stitfened members are welded to the legs of the plane base piece.

5. A snap action device made from a single blank of metal comprising a base piece, two stiffened members connected one to the other at one end by a connecting member fixedly mounted on said base piece and at the other end by a contact carrying member, each of said stiffened members having an elastically deformable bulge projecting from the plane of the stiffened member adjacent its mounted end, two symmetrically arranged spring members disposed between said stiffened members and acting as compression springs, said spring members connected at one of their ends to said contact carrying member and connected at their other end to a third stiffened member, said third stiffened member disposed between said spring members and fixedly mounted on said base piece at its end opposite it its end connected to said spring members, whereby said third stiffened member is an actuator.

6. A snap action device as defined in claim 5 characterized by the fact that the outer longitudinal edges of the first mentioned two stiffened members are bent over to increase the stiffening effect.

7. A snap action device as defined in claim 6 characterized by the fact that the third stiffened member is stamped with a longitudinally extending trough whereby the stiffening effect is increased.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Re. 23,412 Hollis Sept. 25, 1951 2,170,748 Eaton Aug. 22, 1939 2,246,581 Fetter June 24, 1941 2,404,874 Wohl July 30, 1946 2,476,045 Kaminky July 12, 1949 2,508,040 Ransome May 16, 1950 2,565,790 Van Ryan et a1. Aug. 28, 1951 2,571,453 Jackson Oct. 16, 1951 2,589,463 Miller Mar. 18, 1952