US2853573A

US2853573A - Snap-action switch

Info

Publication number: US2853573A
Application number: US558006A
Authority: US
Inventors: Gordon C Wang
Original assignee: Burroughs Corp
Current assignee: Unisys Corp
Priority date: 1956-01-09
Filing date: 1956-01-09
Publication date: 1958-09-23
Anticipated expiration: 1975-09-23

Description

Sept. 23, 1958 I GORDON c, WANG 2,853,573

I SNAP-ACTION SWITCH Filed Jan. 9, 1956 Fig. 1

//y/////////Z //A 435 INVENTOR.

GORDON c. WANG BY United States Patent l SNAP-ACTION SWITCH Gordon C. Wang, Detroit, Mich., assignor to Burroughs Corporation, Detroit, Mich., a corporation of Michigan- Application January 9, 1956, Serial No. 558,006

4 Claims. Cl. 200-67) This invention relates to a device for imparting a snapaction movement to a movable member, and to an electric switch utilizing such device for rapidly making and breaking its contacts.

Numerous types of snap-action devices .are known for moving the movable contact of an electric switch into engagement or disengagement with its fixed contacts. This invention is an improvement of the snap-action devices and the switches utilizing same heretofore .known, in that among its many advantages it permits the construction of relatively small and compact switches and requires a relatively light force to actuate the switch.

An object of the invention, therefore, is to provide a snap-action device which by its inherent design and arrangement of parts permits the construction of relatively small and compact electric switches.

Another object is to provide a snap-action device for moving a movable member which requires a relatively light force to actuate same, which is made of relatively few and simple parts, and which is sensitive and positive in operation.

A further object is to provide an electric switch which utilizes the novel snap-action device and which is versatile in the position it can be mounted and the manner it can be actuated.

These and other objects will be apparent from a description of the invention which is hereinafter described for illustrative purposes as embodied in a snap-action switch for controlling a pair of electrical circuits. The improved snap-action device, as embodied in this switch, is characterized by a resilient over-center connection pivotally seated atone end on a round, smooth bearing surface and engaging the movable contact member of the switch at its other end. As disclosed, the bearing surface is a spherical bearing member and is movable by the switch actuator to rock the over-center connection, thereby imparting a snap-action movement to the switch contact. The switch housing described is so constructed that the switch can be mounted in a number of alternative positions and can be easily converted for operation by the usual actuator or by an additional operator member.

In the drawing illustrating a preferred embodiment of the invention:

Fig. 1 is a perspective view of a snap-action switch embodying the invention in which the front cover is removed to show the internal structure;

Fig. 2 is a front elevation of the switch of Fig. l with the cover and the auxiliary operator member removed, showing the switching mechanism in its normal condition;

Fig. 3 is a similar view of Fig. 2 showing the switch mechanism in its actuated condition;

Fig. 4 is a longitudinal sectional view along the lines IVIV of Fig. 2; and

Fig. 5 is a fragmentary perspective view of the resilient over-center connection and the spherical bearing on which it is seated included in the novel snap-action device.

The switch illustrated is of the type adapted to control ,a pair of electrical circuits and is best shown in Fig. 1 as 2 ,853,573 Patented Sept. 23, '1958 comprising generally a housing 2, a pair of fixed contacts 3 and 4 within the housing, and a movable contact memelongated rectangular recess 12 and a narrower rectangular recess 13 to accommodate the internal elements when the switch is assembled.

The top wall 14 of the housing is formed with a slot communicating with internal recess 7, in which slot the switch actuator 6 is disposed. The actuator normally extends through the housing to be manipulatable from the exterior thereof and terminates in enlarged lateral shoulders 15 which serve as stops to limit its outward movement from the housing.

Housing 2 and its cover plate 8 are further formed with a plurality of apertures 16 for attaching the switch to a support in any one of a number of alternative positions. A notch, or cut-out 17, is formed in one end of the top wall 14 of the housing to accommodate an operator 18 for the actuator 6 if desired, as will be described below.

The two fixed contacts 3 and 4 are supported from an end wall of the housing in cantilever fashion and are provided at their free ends with contact buttons 3' and 4', respectively. The opposite ends of thefixed contacts 3 and 4 extend through the housing and terminate in

apertured lugs

23 and 24 for connection, as by soldering, to the conductor wires of the electrical circuits to be controlled by the switch. Similarly, the movable contact 5 is also supported in cantilever fashion from an end wall of the housing, between the two fixed contacts 3 and 4, and terminates in an exterior lug 25 for connection to the electrical circuit. Near the opposite end of movable contact 5, upper and lower contact buttons 5 are provided to engage selectively the respective contact buttons 3' or 4' upon actuation of the movable contact. Fixed contacts 3 and 4 are formed of relatively rigid, elongated metal strips, whereas movable contact 5 is formed of a thinner metal strip enabling it to be flexed for selective engagement of contact buttons 3' and 4, and is laminated to a thicker metal strip 27 extending from the supporting end wall of the housing exterior thereto to provide the relatively rigid terminal lug 25.

The supporting ends of the fixed and the

movable contact members

3, 4 and 5 are fixed to the end wall of the housing'2 by conventional bonding techniques and may be further provided with laterally extending lugs 28 adapted to enter the rectangular recess 13 of the cover plate 8 and similar recesses in the housing, when assembled, tosecurely anchor these members within the housing.

At the contact buttons 5' end 'of movable contact5, the latter terminates in a reduced portion, or lug, 30 (see Fig. 5) adapted to be pivotally linked to the resilient over-center connection comprising coil spring 31 and end cap 32. The latter is formed with a central elongated slot 34 through which lug 30 passes. The slot 34 is of slightly larger dimension than the lug 30 to permit the latter to pivot therein when the snap-action mechanism is actuated.

The other end of coil spring 31 is pivotally seated on the smooth round surface of bearing member 33, the latter also being engaged, and actuated by, actuator member 6 with which it is coaxially disposed. Bearing 33 is preferably a nylon plastic ball and is urged upwardly by a second coil spring 35, seated in recess 36, to its normal position as limited by the shoulders 15 of actuator 6- 3 abutting-against-the inner-surface of housing 2. As will be seen-from the operations-presently to be described, upon depression of actuatonfi, the spherical bearing mem- 'ber 33 will be moved downwardly against the action of coil spring 55 to actuate'the resilient over-center connection and, thereby,--the movable contact 5.

Fig. 2 illustrates the elements of the switch mechanism in their normal position. In this position, spring 35 urges spherical bearing 33 to its uppermost position asde'termined by shoulders 15 of actuator 6 abutting against the inner surface of the housing. Spherical bearing 33, in this position, is over-center of the longitudinal axis of contact member 5, whereby coil spring 31 of theresilient overcenter connection urges contact to its lowermost position in contact with button 4 of fixed contact 4. Upon depression of actuator 6, bearing 33 is moved against the fforce of spring 35 towards the longitudinal axis of movable contact 5 and in a linear path substantially perpendicular to this longitudinal axis. As the pivotal surface of spring 31 on hearing 33 approaches and passes this longitudinal axis of the movable contact, spring 31 pivots *by a snap-action on hearing 33 to the position shown in Fig. 3, and exerts an upward force on lug 30 of the -movable contact, flexing the latter upwardly into engagement with contact button 3' of the upper fixed contact 3. Upon release of actuator 6, the over-center resilient connection is restored by a snap-action to its normal position of Fig. 2 by coil spring 35.

It is seen from the above operation that the movement of spherical'bearing 33 is confined to a linear path, by spring 31 constantly urging it against the inner surface of the housing side wall, in line with the path of movement of the actuator 6 and substantially perpendicular to the longitudinal axis of movable contact 5; and that spring 31, as it pivots, actually moves slightly along the smooth round surface of bearing 33. These characteristics of this arrangement reduce the size of the over-center resilient connection and its actuating elements necessary to impart the snap-action movement, over the arrangements heretofore known. Thus, this design inherently permits the construction of relatively small and compact electric switches.

The various elements are relatively few and simple and can be easily made on a mass production basis. The resistance to actuating the device is primarily that imposed by spring 35, which can be a relatively light spring. The device, therefore, requires a relatively light force to actuate it, and yet it is sensitive and positive in operation.

Moreover, the switch is versatile in the manner of its operation. In some instances it may be desirable to operate the switch directly through actuator 6 while in other instances it may be desirable to operate the switch through an auxiliary operator member 18. As mentioned earlier, the housing 2 is so constructed that it can be easily converted for either operation. Operator 18 may be easily mounted in the notch or cut-out portion 17 of the housing top wall 14. For this purpose, the operator member is formed near one end with a pair of parallel slits and deformed to straddle a pin 41 press-fitted through apertures 42 in the housing 2 and cover plate 8. The operator member is then angled upwardly at 43 and terminates in a flat portion 44 paralleling the top wall 14 of the housing and engaging actuator 6. The mechanism operating the switch, such as a cam follower, can contact either

portion

43 or 44 of the operator, whichever is more convenient, and the latter will be rocked on pin 41 to depress actuator 6. Operator 18 can also be made of resilient material in which case it would be flexed by the actuating mechanism.

While the invention has been described in connection with a preferred embodiment of an electric switch, it will be apparent that it is susceptible of other embodiments and obvious modifications within the skill 'of the art and the scope of the appended claims.

I claim:

1. A snap-action switch comprising a housing provided with an interior recess to form top, bottom and first and second side walls, a fixed contact mounted in said recess, a resilient contact mounted in cantilever fashion from said first side wall in juxtaposition to said fixed contact, and actuating means for flexing said resilient contactiinto engagement with the fixed contact, comprising an actuator extending through a slot in the top wall of the housing adjacent said second side wall, said actuator being movable in a rectilinear path, a bearing member in said recess adjacent said second side wall and coaxially disposed with respect to said actuator, said bearing member having a smooth round surface and being movable by said actuator along the same axis of movement as said actuator, and a resilient over-center connection engaging at one end the free end of the resilient contact and being pivotally seated at its opposite end on the smooth round surface of the bearing member, whereby the resilient contact is caused to engage the fixed contact by a snap-action as the bearing member is moved by said actuator.

2. A snap-action switch as set forth in claim 1 including a spring seated on the interior surface of the bottom wall of the housing and engaging the bearing member to urge same to its normal position.

3. A snap-action switch as set forth in claim 2 wherein the bearing member is a sphere and is constantly urged-by the resilient over-center connection against the interior surface of the second side wall to confine its movement to a rectilinear path.

4. A snap-action switch as set forth in claim 3 wherein the resilient over-center connection comprises a spring pivotally seated on the bearing member and a slottedcap engaging the resilient contact.

References Cited in the file of this patent UNITED STATES PATENTS 1,303,196 Gordon May 6, 1919 1,312,692 Hornung Aug. 12, 1919 1,372,331 Balzer et'al Mar. 22, 1921 1,949,694 Poli Mar. 6, 1934 2,441,614 Baumer May 18, 1948 2,574,429 Wood Nov. 6, 1951 2,727,956 Winter Dec. 20, 1955 2,743,330 Ludwig Apr. 24, 1956 2,743,332 Torres Apr. 24, 1956 FQREIGN PATENTS 722,734 Germany July 20, 1942