US2618715A - Snap switch - Google Patents

Description

NOV. 18, 1952 J, Q CATALDO v2,618,715

SNAP SWITCH Filed Feb. 11. 195o INVENToR. MOH/v O4 74u20 .Patented Nov.v 18, 1952 SNAP swrrcn John B. Cataldo, Bernardsville, N. J., assignor to John B. Pierce Foundation, New York, N. Y., a corporation of New York Application February 11, 1950, Serial No. 143,666

(Cl. 20o- 76) 6 Claims.

This invention relates to snap switches and more particularly to snap switches of the type providing either momentary or sustained circuit conditions utilizing snap springs as their fundamental components.

The useful life of the contact elements of an electrical switch, for example, may be dependent upon the ability of the switch mechanism to maintain uniformly high contact-engaging pressures under static conditions and to provide rapid make-break characteristics when the switch is 'a snap switch assembly utilizing a minimum number of moving parts to facilitate rapid assembly and relatively faultless operation.

It is yet another object of the invention to provide snap switch assemblies utilizing snap springs as their fundamental components and whereby snap springs having various characteristics may be incorporated in the assemblies to provide snap switches of various types, such, for example, as a momentary switch which may be maintained in a circuit-closed position with less force than is required to initially make the circuit.

According to the invention, one or `two snap springs may be mounted in a suitable housing to partake of snap action out of given configurations of equilibrium under the control of a manual control arm, with the snap action of the spring or springs being utilized to control the makebreak action of the electrical contacts. Preferably two springs are mounted in opposed relationship so that selective switch action may be provided dependent upon the direction of movement of the control arm.

The above and other objects of the invention will be better understood from the following description of a preferred embodiment thereof taken in conjunction with the accompanying drawings, in which:

Fig. l is a bottom view of a snap switch assembly incorporating the invention;

Fig. 2 is a view in longitudinal cross-section formed by the vertical plane containing the line 2-2 of Fig. 1 and looking in the direction of the arrows;

Fig. 2a is a view of the portion of the switch as shown in Fig. 2 with the switch having been actuated to close one pair of contacts;

Fig. 3 is a view in longitudinal cross-section as formed by the vertical plane containing the line 3 3 o! Fig. 1 and looking in the direction of the arrows;

Fig. 3a is a view of a portion of the switch assembly shown in Fig. 3 with the switch having been actuated to close a second set of contacts, and

Fig. 4 is a view in longitudinal cross-section of a portion of the snap switch formed by the vertical plane containing the line 4-4 of Fig. l and showing the mounting brackets for supporting the snap springs.

The snap switch includes a cup-shaped housing I0 having a threaded bushing II seated and riveted in a central opening Iba in its upper surface. An insulating end plate I2 is secured in the lower end of the housing by means of bentover ears I3 formed on the lower edge of the housing. An insulating shelf-portion I4 is amxed in an intermediate position within the housing and four upright bracket members I5 arrayed at intervals to define a circle are secured between the upper surface of the shelf portion and the inner surface of the housing by means of bent ears I5a, at either extremity thereof (Fig. 4). Each of the four brackets I5 is formed with a notch |51) on its inner edge to receive the rim portions of a pair of dished monometallic spring discs I6 and I1 to provide a four-point disc mounting assembly. The discs are coaxially disposed in inverted relationship with respect to their dished congurations of equilibrium and the rim portions are in circumferential, mutually spring-biasing engagement.

An actuating shaft I8, furnished at its free end with a knob Ita, is slidably received in a bore I9 in the bushing II and extends downward into the switch housing. A shaft extension 20 is disposed within the housing in axial alignment with the shaft I8, and is secured thereto by a suitable threaded joint 2|. The upper portion of the shaft 20 is necked down at 22 to form a disc-mounting portion extending through central apertures in each of the spring discs IB and I1. Thus the inner end Ib of the actuating shaft I8 forms a bearing shoulder for the upper surface of the disc I6, and an annular shelf 23.

formed on the shaft 20 forms a bearing shoulder for the lower surface of the disc I7, the opposedA bearing shoulders being so spaced that the discs are compressed therebetween to provide firm rim engagement.

In a preferred embodiment of the invention, the two opposed snap springs I3 and I'I are of the single equilibrium type and preferably comprise monometallic snap spring discs of the type disclosed in the following pending U. S. applications: Serial No. 628,447, filed November 14, 1945, entitled: Toggle Springs; Serial No. 635,956, filed December 19, 1945, entitled: Snap DiscSprings; and Serial No. 139,182, filed January 18, 1950, entitled: Snap Disc Springs a Methods of Manufacture.

The single equilibrium spring discs I6 and il are normally disposed, as shown in Fig. 2, in their respective opposed configurations of single equilibrium. By pulling the shaft I8 outward the snap disc Il may be forced by means of the shoulder 23 to snap into its relatively less stable configuration, as shown in Fig, 2a, wherein it overlies the unactuated disc I6. Releasing the shaft I8 enables disc I'l to snap-return to its position of stable equilibrium (Fig. 2). In either direction of movement between the stable and unstable configurations, however, the disc partakes of snapping action, this by virtue of the inherent characteristics thereof. 'I'he shaft I8 may also be pushed inward to initiate snapping of the upper disc I6 into its unstable configuration (Fig. 3a), and when the shaft is released the disc will revert to its initial configuration similarly to the action of the disc Il.

The characteristics of the discs I6 and II as formed according to the disclosures in the above pending applications may be such that it requires a greater force in order to displace them from their respective configurations of equilibrium than is required to maintain either of them in their relatively less stable configurations.

A preferred electrical contact assembly for use with the above arrangement of snap springs includes a depending threaded shaft portion 24 in axial alignment and formed integrally with the movable shaft 20. The shaft portion 24 has a pair of opposed lock-nuts 25 threaded thereon embracing a metallic hub 2S supporting a first pair of aligned, resilient contact-carrier arms 2'I and a second pair of aligned resilient contactcarrier arms 28, the latter arms being perpendicular to the first pair of arms 2l (Figs, 2 and 3 respectively). Each ofthe arms 21 and 28 and the hub portion 26, is formed of electrical conducting material and, in assembly, comprise a four-point star or cross.

The contact-carrier arms 2'I are furnished adjacent their free ends with a pair of contact elements 29 adapted to engage a pair of stationary contact elements 30, received in suitable mounting bores in the intermediate shelf I4. A pair of conducting leads 3I are joined to the upper ends of the stationary contact elements 3Il` and extend outwardly along the upper surface of the shelf I4 and thence downwardly through accommodating slots in the edge of the shelf I4 and in the edge of the end plate I2, terminating in terminal screws 32.

The contact-carrier arms 28 (Fig. 3) are furnished adjacent their free ends with contact elements 33, and are adapted to engage a corresponding pair of stationary contact elements 34 secured in the end plate I2, with suitable terminal lugs 35 being connected thereto.

In operation, as the actuating shaft I8 is pulled position of unstable equilibrium, as shown in Fig.'

2a, the movable contact elements 29 are snapped into rapid and relatively forceful engagement with the corresponding stationary contact elements 30, with the carrier arms 2l and the hub 28 forming a shorting bar therebetween to close an appropriate electrical circuit (not shown) connected across terminals 32.

Releasing shaft I8 enables the spring disc Il to snap shaft I8 into a neutral position (Figs, 2 and 3) in which all circuits are open. Pushing the shaft I8 inwardly causes similar snap action on the part of the spring disc I6,-driving contact elements 33 into sudden engagement with the stationary contact elements 34 disposed thereunder, with the hub 26 and the arms 2l forming e, shorting bar therebetween to close a second electrical circuit (not shown).

Thus there is provided a double-throw, momentary push switch having rapid make-and-break characteristics in the nature of a toggle switch. Accordingly, excellent protection is afforded the several contact elements, the unit nevertheless being comprised of comparatively few moving parts, which are readily susceptible of assembly on a mass production basis. It will be apparent of course that the double-throw-momentary switch may be reduced to a single-throw-momentary switch, i. e. a switch momentary'on a single side, simply by removing one single equilibrium disc in favor of a conventional disc having two sustaining configurations of equilibrium.

If preferred, the discs IB and Il may be arranged in reversed or back-to-back arrangement with respect to their stable configurations of equilibrium, with the shoulders on the shaft I8, which initiate snap movement, being disposed between the discs; or the discs may be centermounted on a stationary post and a suitable spider assembly afiixed to the shaft I8 for selectively initiating peripheral snap movement of either of the discs.

Moreover, certain variations may be provided in the design and construction of the contact assembly of the switch, with more sets of contacts being secured to the shaft extension 20 to obtain various multiple-circuit arrangements. If preferred, coil springs may also be added to the momentary contact type switch to increase the contact gap, as described in the pending U. S. application, Serial No. 777,688, filed October 3, 1947 entitled: Resilient Motivating Device.

It Awill be understood therefore that the specific switch assembly disclosed herein for purposes of illustration may be widely varied within the spirit of the invention which should accordingly be determined in scope by the following claims.

I claim:

1. A snap switch assembly comprising first and second snap springs at least one of which has only one configuration of equilibrium, means for mounting said springs enabling snap displacement out of said configurations of equilibrium, a control arm having two directions of switch-actuating movement, linkage means connecting said arm to each of said snap springs,

connected to the first and second springs to be actuated thereby.

2. A snap switch assembly including first and second snap springs at least one oi which has only one conguration of equilibrium-means for mounting said springs enabling snap displacement out of said conigurations oi equilibrium, a control arm adapted to be moved in two operative directions, means connecting said arm to the first spring to initiate snap displacement of the latter out of its coniiguration of equilibrium upon movement of the arm in one direction, means connecting said arm to the second spring to initiate snap displacement thereof upon movement of the arm in the other direction, first electrical contact means adapted to be actuated upon snapping of said iirst spring in one direction, and second electrical contact means adapted to be actuated upon snapping of the other spring in one direction.

3. A snap switch assembly comprising first and second snap springs each having only one configuration of equilibrium, means for mounting said springs enabling snap displacement out of said congurations oi equilibrium, a control arm having first and second directions of movement, linkage means connecting said arm to each of said springs, said linkage initiating snap movement of said iirst spring out of its conguration of equilibrium upon movement of said control arm in a first direction and providing a lost motion connection between the second spring and the arm for said ilrst direction of movement, said linkage initiating snap movement of the second spring out of its configuration oi' equilibrium upon movement of said control arm in the second direction and providing a lost motion connection between said first snap spring and said arm for the said second direction of movement, and work means operatively connected to the iirst and second snap springs to be selectively initiated by the respective snap actions o! the said springs.

4. A switch assembly including a pair of snap springs each having at least one coniiguration of equilibrium, means for mounting said springs in opposed relationship with respect to their conguration of equilibrium, unitary control means for selectively displacing either of said springs from its position of equilibrium, work means adapted to be displaced between two operative positions, and positive driving connectionsbetween said snap springs and said work means whereby the latter is actuated concomitantly with the snap action of the respective springs.

5. A snap switch assembly comprising nrst and second snap discs each having at least one dished coniiguration of equilibrium, means for mounting said discs in substantially coaxial and spaced relationship and opposed with respect to their configurations of equilibrium, said discs being mounted to be displaced out of their conn'gurations of equilibrium in opposite directions, a slidably mounted control arm adapted to partake of control movement in two directions. first shoulder means on said arm adapted to initiate snap action of the iirst of said discs out of its configuration o1' equilibrium upon movement of the control arm in one direction, second shoulder means on said arm adapted to initiate snap action of the other of said discs out of its configuration of equilibrium upon movement of said arm in the other direction, and electrical contact means operatively connected to said snap discs.

6. A snap switch assembly comprising rst and second snap discs each centrally apertured and each having at least one dished configuration of equilibrium, peripheral mounting means for said discs enabling the center portions thereof to partake oi snap displacement out of said coniigurations oi equilibrium. said discs being mounted in coaxial spaced relationship and inverted with respect to their conngurations of equilibrium. a reciprocatable control arm slidably received in the central aperture of each of said discs, first shoulder means on said arm for initiating snap displacement of the center portion of one of said discs out o! its configuration of equilibrium upon movement o! said arm in one direction, second shoulder means on said arm for initiating movement of the central portion of the second disc out' oi its conilguration of equilibrium upon movement ot the arm in the other direction, and nrst and second oontact means operatively connected to the center portion of the said nrst and second discs, respectively, to be actuated upon mapping ot the discs.

JOHN B. CATALDO.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Stilwell, J1'. Oct. 16, 1051

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