US3566057A - Snap switch with dual flexible members and insulating bearings - Google Patents

Abstract

A snap-action electric switch having an overcenter mechanism including oppositely bowed spring leaves pivotally anchored with their adjacent ends to opposite insulating members, respectively, and being extended in passing of the mechanism from either stable position through a dead center position to the other stable position, with at least one of the spring leaves having at its ends bent lugs with contacts which on extension of the leaf undergo angular displacement so as to have a wiping action on associated fixed contacts on their engagement therewith.

Description

United States Patent [72] Inventor August Reinke 1 Wiedenhoikamp, Radevormald, Germany [21] App], No. 831,126

[22] Filed June 6, 1969 [45] Patented Feb. 23, 1971 [32] Priority July 4, 1968 [33] Germany [54] SNAP SWITCH WITH DUAL FLEXIBLE MEMBERS AND INSULATION BEARINGS 7 Claims, 9 Drawing Figs.

[52] US. Cl 200/76, ZOO/67 [51] Int. Cl ..H01h 15/18 [50] Field of Search 200/67,

[56] References Cited UNITED STATES PATENTS 1,861,046 5/1932 Bower 200/76(UX) 2,608,628 8/1952 Dietrich 200/76 3,017,471 H1962 Karch 200/76 Primary Examiner-D. Smith, Jr. Attorney-Walter Spruegel ABSTRACT: A snap-action electric switch having an overcenter mechanism including oppositely bowed spring leaves 7 pivotally anchored with their adjacent ends to opposite insulating members, respectively, and being extended in passing of the mechanism from either stable position through a dead center position to the other stable position with at least one of the spring leaves having at its ends bent lugs with contacts which on extension of the leaf undergo angular displacement so as to have a wiping action on associated fixed contacts on their engagement therewith.

PATE NIED E 3,566,057

SHEET 1 OF 2 Fig.

Fig. 7

PATENTED FEB23 \sm SHEET 2 OF 2 SNAP SWITCH WITH DUAL FLEXIBLE MEMBERS AND INSULATION BEARINGS The invention relates to electric switches in general, and to electric switches of snap-action type in particular.

In known snap switches, flat springs are usually employed which by reason of their special shaping serve as snap elements when they are flexed by means of a plunger. Furthermore, quick-acting switch arrangements are also known in which a compression spring is arranged inside a spring plate or cap and two knife edges are mounted in knife-edge bearings of an insulating body on the one hand, and in bearings on the spring plate on the other hand. Moreover, snap switches are known which include a movable framelike closed contact bridge having a contact lug at each of the narrow ends, with the two contacts being conductively connected with one another, and the contact bridge can only be used for singlecircuit switches. The contacts are fixed on the contact bridge and are not movable relative thereto.

The objective of the present invention is to provide a snap switch which overcomes the drawbacks of the known snap switch devices, and which in particular, switches over substantially independently of the speed of actuation of the plunger, has a neutral zone at the dead center, applies a frictional effect at the contact points in order to avoid sticking and fouling of p the same, and has two contact bridges separated from one another by means of which it is possible safely to switch either of two separate circuits without making any connection with the other circuit in the event of malfunctioning of the switch, for example due to sticking of a contact point. V

According to the present invention, the snap switch includes contact bridges which are separated from one another, are resiliently flexible along their longitudinal axis, are arranged symmetrically with respect to their longitudinal axis and provide the contacts at the opposite terminal connection common plane and rest on the insulating bodies.

Each insulating body has a bearing for one end edge of a rigid longitudinal compression member the opposite end edge of which is mounted in a bearing on the actuating plunger. The insulating bodies separate the contact'bridges of the switch and keep them insulated from each other. Provided on each insulating body are projections which extend through apertures in the contact bridges and thus pivotally connect the contact bridges with the insulating bodies.

According to a preferred constructional form of the invention, the contact bridges are in each case curved spring leaves lying with their planes at right angles to the plane of their contacts and admit between them the switch plunger which is under spring bias.

On actuation of the switch plunger, the rigid compression members or leaves force the curved contact bridges to straighten and thereby expand in longitudinal direction, whereby the bridge contacts, which are the movable contacts, move with a turning and rubbing action on the surfaces of the stationary contacts. The contact pressure is'a factor of the force component of the contact bridges and of the force component of the rigid leaves which form obtuse angles with the lugs of the contact bridge bearing the movable contacts which are then in engagement with fixed contacts. On depression of the plunger, the angle of the leaves with these contact lugs is reduced, with ensuing steady decrease of the contact pressure until the snap point is reached. Due to the particular shape of the resilient contact bridges, a nonlinear, abrupt increase in force is obtained on their longitudinal elongation which causes the contact pressure to remain relatively high until the snap point is reached. When the rigid leaves pass the zero working line, i.e., the line on which they no longer form an obtuse angle with the respective contact lugs, the movable contact arrangement snaps sharply to the opposite fixed contacts, the rigid leaves again immediately formimg an obtuse angle with the other contact-carrying bridge lugs on this snap-over action, whereby the contact pressure for these other movable contact points is obtained. On return of the plunger to the initial position, either positively or by means of a return spring, this action is repeated in reverse.

An embodiment of the invention is described hereinafter with reference to the drawings. In the drawings:

FIG. 1 is a part-sectional and part-elevational view of a switch according to the invention;

FIG. 2 shows diagrammatically the rest position of the switch;

FIG. 3 shows diagrammatically the condition of the switch immediately before the snap-over;

FIG. 4 shows diagrammatically the condition of the switch after snap-over;

FIG. 5 shows diagrammatically the condition of the switch immediately before its return to rest position;

FIG. 6 is a diagrammatic view of the switch in its rest position which is identical to that of FIG. 2;

FIG. 7 is a diagrammatic view of the switch in plan view;

FIG. 8 shows the contact bridges andassociated insulating bodies of the switch in exploded perspective view, and

FIG. 9 shows in perspective the complete snap-over part of a switch according to the invention.

The complete structure of the switch according to the invention is shown in FIG. 1. A casing 1, preferably of insulating material, accommodates a plunger 2 which constitutes the switch actuating member. This plunger 2 is guided in the top and bottom walls of the casing I and is subjected to the action of a compression spring 3 which returns the plunger to its initial or rest position every time the depressing force acting on the plunger is removed. The contact bridge arrangement 4 in the switch has its operating plane arranged at right angles to the axis of the plunger. This contact bridge arrangement 4 includes insulating bodies 5 in which the end edges of rigid leaves 6 are mounted. One end edge of each leaf is mounted in a bearing 7 of the insulating body 5 and the opposite end edge is mounted in a bearing 8 on the plunger. The contact bridge arrangement 4 has in a plane parallel to its plane movable contacts 9 on both sides of the plunger and on both sides of the contact bridges. These movable contacts 9 cooperate with stationary contacts 10, the switch illustrated in the drawing being designed as two-circuit changeover switch.

FIGS. 2 to 6 show different positions of the contact bridge arrangement and leaf bearing system, the switching from the rest position to the changed-over position and back being illustrated step by step: In FIG. 7, the two curved dash lines indicate the disposition of the contact bridges in the rest position of the switch, while the curved solid lines indicate the disposition of the contact bridges when the switch snaps into its other position. I

. FIG. 8 shows the contact bridge arrangement and the two associated insulating bodies in detail and on a larger scale. The contact bridges 11 are spring leaves having at their wider ends lugs extending at right angles thereto and carrying the movable contacts 9. The contact bridges have attheir ends apertures 13 in which projections 14 on the insulating bodies 5 engage, these projections 14 being extended through the apertures l3 and pivotlike connections between the insulating bodies 5 and the contact bridges 11 being thereby obtained.

FIGS. 8 and 9 show particularly clearly the bearings in the inthe length of the assembly, and insulating members to which the adjacent ends, respectively, of said-flexible members are attached with pivotal freedom, and which are also engaged by said compression members, with said members defining an overcenter mechanism capable of transfer from one stable position to the other stable position through a dead center position under the control of said operating member, at least one of said flexible members serving as a conductive bridge and having at its ends moving contacts lying in a plane at right angle to that of said bridging member, and fixed contacts associated with said moving contacts, with said moving contacts undergoing angular displacement as a result of extension of said bridging member in passing from one stable position to the other and thereby exerting a wiping action on said associated fixed contacts.

2. A snap-action electric switch as in claim 1, in which both of said flexible members serve as conductive bridges with each having said moving contacts at its ends.

3. A snap-action electric switch as in claim 2, in which each of said bridges is at its ends formed with bent over lugs carrying the movable contacts, with said lugs of each bridge lying in the same plane and being spaced from said lugs of the other bridge by said insulating members.

4. A snap-action electric switch as in claim 1, in which said operating member and said insulating members have grooves in which said compression members are received with their ends.

5. A snap-action electric switch as in claim 1, in which said flexible members are spaced, and said operating member and compression members are arranged in the space between said flexible members.

6. A snap-action electric switch as in claim I, in which said flexible members are formed by oppositely bowed spring leaves.

7. A snap-action electric switch as in claim 1, in which said flexible members have openings in their opposite ends, and said insulating members have projections extending through said openings to hold said flexible members at their ends with pivotal freedom.

Claims (7)

1. A snap-action electric switch, having a contact assembly with a pair of rigid compression members, a central operating member from which said compression members extend outwardly, a pair of resiliently flexible members extending along the length of the assembly, and insulating members to which the adjacent ends, respectively, of said flexible members are attached with pivotal freedom, and which are also engaged by said compression members, with said members defining an overcenter mechanism capable of transfer from one stable position to the other stable position through a dead center position under the control of said operating member, at least one of said flexible members serving as a conductive bridge and having at its ends moving contacts lying in a plane at right angle to that of said bridging member, and fixed contacts associated with said moving contacts, with said moving contacts undergoing angular displacement as a result of extension of said bridging member in passing from one stable position to the other and thereby exerting a wiping action on said associated fixed contacts.

2. A snap-action electric switch as in claim 1, in which both of said flexible members serve as conductive bridges with each having said moving contacts at its ends.

3. A snap-action electric switch as in claim 2, in which each of said bridges is at its ends formed with bent over lugs carrying the movable contacts, with said lugs of each bridge lying in the same plane and being spaced from said lugs of the other bridge by said insulating members.

4. A snap-action electric switch as in claim 1, in which said operating member and said insulating members have grooves in which said compression members are received with their ends.

5. A snap-action electric switch as in claim 1, in which said flexible members are spaced, and said operating member and compression members are arranged in the space between said flexible members.

6. A snap-action electric switch as in claim 1, in which said flexible members are formed by oppositely bowed spring leaves.

7. A snap-action electric switch as in claim 1, in which said flexible members have openings in their opposite ends, and said insulating members have projections extending through said openings to hold said flexible members at their ends with pivotal freedom.

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