US2500476A - Snap switch - Google Patents

Description

March 14, 1950 w.- VON STOESER SNAP SWITCH Filed April 4, 1949 Patented Mar. 14, 1950 SNAP SWITCH Walter Von Stoeser, Lake Villa, Iii., assignor to Raymond T. Moioney, Chicago, Ill.

Application April 4, 1949,: Serial No. 85,455

, 'lClaims. (01.200-67) This invention pertains to snap action devices, particularly switches operating upon the overcenter principle.

Among the important objects of the improvement are the provision of a simple over-center, snap-action mechanism suitable for use in the jack-type or leaf-spring switches where economy of space is of particular importance.

A further object is the provision of a snapaction mechanism for use in leaf-spring switches in which a moving contact and an over-center spring element are formed integrally and substantially within the average dimensions for similar contact structures in the ordinary leaf-spring or jack-switch.

A further object is the provision of an integral spring and contact, element having cut out formations dimensionally to control the sensitivity of snap action.

A further object is the provision of a simplifled over-center mechanism for switches consisting of an elongated contact spring fixed at one end and having an integral bow at its opposite end with contacts or stops on opposite sides of the spring near the bow, and another long spring fixed at an end with the contact spring and having a cut-away enabling it to spring back and forth over the contact spring, together with an actuator rocking on the second spring and seated in an end of the bow such that movement of the second spring up and down rocks the actuator into opposite positions past center and snaps the fixed contact spring into opposite positions through spring effort set up in the bow.

Additional objects pertain to the details of the bow and actuator structure, and other features of construction and operation of the preferred embodiment described hereinafter in view of the annexed drawing, in which:

Fig. 1 is a top plan view of the improved switch structure;

Fig. 2 is a side elevation of the same in a normal condition of operation with parts cut away to expose structural details;

Fig. 3 is a view similar to that of Fig. 2 with the switch in a different condition of operation;

Fig. 4 is a vertical sectional detail looking in the direction of lines 4-4 of Fig. 2;

Fig. 5 is a perspective detail of the actuator I element;

Fig. 6 is a magnified perspective fragment of 2 Fig. 8 is a fragmentary detail of a modified form of actuator, in mounted position;

Fig. 9 is a perspective detail of the modified actuator.

The type of switch illustrated in the drawings is well-known in the art under various names,

such as jack-switch leaf-spring switch, stackswitch, etc., and these switches are characterized mainly in that the contacts thereof consist of a pluralityv of elongated flat spring fingers secured together in spaced relation in a stack of insulating wafers disposed at one end of the array such that the opposite free ends of the springs may be moved to flex the same into or out of contacting engagement with one Or more of the other contact springs in the stack.

Snap-action switches and mechanisms are also of great variety in the art, and snap-action principles have been applied heretofore to the jackswitch, the latter applications generally involving the use of a separate spring toggle between an operating member and a contact spring t which snap action is imparted.

In the manufacture of stack-switches or jackswitches tolerances are often of great importance in conjunction with clearances between contacts and the displacement of acontact spring before make or break occurs, and such criteria become highly important where snap action is involved. since a certain displacement of the operating'arm must occur before the snap action mechanism is conditioned to be triggered and problems arise in connection with maintaining such tolerances,

and preventing false operation, i. e. premature or partial operation or engagement of contacts (where the contact clearances are close) owing to improper operation of the snap-actionv mechanism.

In mass production of these devices, the tolerance problem is of considerable importance where separate spring elements are utilized in a toggle arrangementfor imparting snap action between two relatively movable blade members.

The present improvements afford an advantage in making the principal spring element integral with the member moved, that is to say the snap acting contact blade, and utilizing a relatively rigid activator rocking on and carried by the principal operating blade.

Referring to Fig. 2, the snap switch there shown 'to enlarged scale over natural size consists of a pair of elongated and relatively rigid contact fingers Ill and I I secured at one end in a stack of insulating wafers. l2 clamped together by bolts It. A central spring contact N is similarly fixed in the stack and provided with a contact button I! engageable with similar contact buttons l6 and H on the first-mentioned stationary contacts.

Also fixed at its end in the stack I2 is an elongated spring operator arm l8 having a central cut-out 19 (see also Fig. 1), which may be termed the operator or operating spring, this member being capable of flexure downward from the position of Fig. 2 to that of Fig. 3, the principal contact spring l4 and its appendages being passed through the opening I9 in the operator blade.

At its free end the contact spring I4 is provided with a U-shaped how 20 (Fig. 2) and there is provided a slot 2| (Fig. 6) near the outer end of this bow and into the slot fits the tongue 22 of an actuator element 23 of the general shape shown in Fig. 5.

The actuator 23, as in Figs. 2 and 3, is provided with oppositely pitched lugs 24 and 25 defining a fork, which engages an edge I9X of the cut-out in the operator spring, the actuator 23 being maintained in this condition of assembly by spring action of the bow 20 with the operating arm or spring l8 in the normal condition shown in Fig. 2, a stop 21 (Fig. 1, particularly) of insulating material being included in the stack of wafers l2 so that its ends 21A will be engaged by the opposite arms of the operator spring l8 in its normal position to limit the upward movement thereof as in Fig. 2. I

By application of a slight force to the free end of the operator spring I8 in the downward directionindicated by the arrow in Fig. 2, the actuator 23 will be displaced toward a relatively hori zontal position and will compress the spring how 20 in this action until the actuator reaches a relatively dead center position and passes beyond such position by continued movement of the operator I8, and the actuator 23 rocks into the reverse position'shown in Fig. 3 herein; then the effort-of the spring bow 20 is reversibly directed toengage the contact IS with contact l1. 1

As soon as the downward efiort is released from the operator l8 the latter, is quickly restored to the normal position of Fig. 2 by reasonof the tension therein, and this reverse movevariety of switch specifications, and there is no necessity for matching up operating springs with particular operating blades or actuators; the springs and blades being integral are essentially uniform, assuming properly made and maintained dies, with the result that the finished product tends to be increasingly uniform with regard to the critical tolerances hereinabove alluded to.

A further sensitizing feature, Fig. '7, where thin spring stock is to be used in order to procure a light operating pressure, resides in the provision, additionally to the cut-out bow means .30, of a longitudinal body-rigidifier in the nature of stamped rib 3|, together with bight rigiditying means in the form of an embossment 32 at the inner bight or juncture of the bow oflset with the-main spring body. These provisions make possible a very light spring tension in the how but insure positive contacting and breaking by preventing unwanted displacements or fiexures of the spring leaf X or bight regions 32 during the over-center tensioning movements of the actuator.

In Figs. 8 and 9 is disclosed a variant form of actuator 35 having'two offset ends 36 and 31, the former being provided with a tongue 36a, and the latter with a slot 31a.

On the operator I8a: is formed a tongue I811 which fits into the slot 31a, while the tongue 36a fits into the bow slot 2|.

By selectively predetermining the relative alignment of actuator slot 31a and tongue 36a, particularly with respect to a line joining the same and the long axis of blade M or ldzc-in dead center position, the sensitivity may be further controlled.

The use of the offset type of actuator shown in Fig. 9 permits a limited but convenient degree of manual bending in case it is desired in any particular instant to modify the sensitivity or throw, vwhereas bending the straight type of actuator enough to make a detectable difference ment, like 'the initial movement, occurs with a snap action resulting from the movements of the actuator 23 toward into, and out of relatively over-center position with respect to the spring bow 20 during displacements of the actuator by the operating spring.

A satisfactory commercial embodiment may be proportioned substantially asillustrated, however, the performance of the switch with respect to sensitivity and requisite operating pressure is dependent somewhat on the stock and dimensioning-particularly thickness-of the contact springs i4, and in these respects there are empirical criteria depending upon the requirements of a given, application or use to which the switch is to be applied.

The embodiment of the contact spring HX shown in Fig. 7 includes a cut-out 30 in the bight of the bow and permits the use of a relatively heavy metal stock for the contact proper, without essentially increasing the stifiness or sensitivity of the spring bow portion 20X.

The essential parts of the switch, namely the spring contacts I, X and their respective bow portions 20 and 20X, as well as the actuators 23, are very readily and economically fabricated. One type of actuator may be used for a great tends to shorten its effective length, which is objectionable because then the tension exerted by the bow is altered.

I claim:

1; A snap-acting-stack-switch comprising an elongated spring contact having one end fixed in the stack with a substantially U-shaped bow at its free end, an operating spring similarly fixed in the stack and having a cut-out passing over the fixed contact spring responsive to fiexure, and an actuator having one end pivotally seated in a free end region of said how and an opposite end pivotally engaged with said operating spring for displacement by movements of the latter into and out of over-center relation respective to said bow for snapping said contact spring between opposite positions, and contact means carried by said stack on opposite sides of said contact spring for defining said opposite positions.

2. In a snap-switch an elongated operating spring having a central cut-out, an elongated contact spring having an end portion offset to define a spring bow disposed in the cut-out of the operating spring, an actuator having a forked end rockably engaging an edge of the cut-out in the operating spring and a tongued engagement at its opposite end with a free end region of said bow, said operating and contact springs extending in approximate parallelism and havingcorresponding ends remote from said actuator and bow fixed in a mounting, means on opposite sides of said contact spring near said bow for limiting the displacements of the contact spring, movements of said operating spring in opposite directions moving said actuator into and out of overcenter relation with said bow to efiect snap movements of said contact spring between opposite positions as defined by said displacement limiting means.

3. In a stack-switch, snap action means comprising an elongated flexible operating arm having a cut-out between its ends, with one end secured in the stack, an elongated contact spring fixed at one end in the stack and having its opposite end aligned with said cut-out, a substantially U-shaped bow in said opposite end of the contact spring, the arms of the bow adjoining its bight extending in a direction substantially transverse of the length of the contact spring, said cut-out having a transverse edge spaced outwardly from the free leg of the bow, and an overcenter actuator in the form of a short piece having tongue and slot engagement at one of its ends with said free leg of the bow, and a rocking support with said transverse edge at its other end whereby opposite displacements of said operating arm will move said actuator to and past an over-center position relative to said bow to tension the latter and snap said contact spring in opposite directions, and means limiting opposite movements of the contact spring as aforesaid.

4. In a snap-acting stack-switch of the overcenter variety employing an elongated flexible operating arm secured in the switch stack and having a cut-out to pass the free end portions of a contact spring in the stack, improvements in snap-acting mechanism comprising, to wit: the provision of a lateral bow at said free end of the contact spring, said bow having an outer free leg spaced from a lateral edge of said cut-out, said leg extending approximately transversely of the planes of said contact spring and arm, and a short actuator rockably seated by and between said free leg and lateral edge and of a length to maintain said bow under tension and to further tension the bow responsive to opposite displacements of said arm to move the actuator relative to an over-center position and snap said contact spring back and forth, and contact means engaged by said contact spring in back and forth movement a aforesaid.

5. In a snap-switch of the known leaf-spring or stack variety, improvements consisting, to wit: in the provision of a fiat spring contact blade fixed at one end in the stack and having a lateral bow at the opposite end, lateral displacementlimiting means on opposite sides of said spring near said bow, an operator spring fixed at one end in said stack and having a cut-out in the opposite end region to pass over said bow of the contact spring in lateral fiexure, an actuator piece rockably seated under spring tension between the free leg of said bow and said operator spring, a sensitizing blank in the bight of said bow and longitudinal rigidifying formations in said spring contact blade in the region thereof between said bow and said stack.

6. In a stack-switch, an elongated operator leaf fixed in the stack at one end and having a cutout between its ends, a contact spring fixed correspondingly at one end in said stack and having a free end disposed in alignment with said cutout such that lateral flexing of said operator leaf can move the latter toward and past said free end of the contact spring, a lateral bow formed at said free end of the contact spring, said bow having a free leg projecting in a lateral sense on opposite sides of the longitudinal center line or axis of said contact spring, a slot in said free leg in alignment with said axis, an actuator in the form of a U-shaped member having one offset arm with a tongue at the end thereof, and an opposite straight arm with a slot therein aligned with said tongue, said operator leaf in the cutout thereof having a tongue fitting into the slot of the actuator, and the tongue of the latter fitting into the slot of said bow to place the latter under tension such that opposite lateral flexing of said operator leaf will move the actuator relative to over-center position with said bow and snap said contact spring between opposite lateral limits, and means mounted in said stack and determining said limits.

7. In a snap-switch of the known leaf-spring or stack variety, improvements consisting, to wit: in the provision of a fiat spring contact blade fixed at one end in the stack and having a lateral bow at the opposite end, lateral displacementlimiting means on opposite sides of said spring near said bow, an operator spring fixed at one end in said stack and having a cut-out in the opposite end region to pass over said bow of the contact spring in lateral fiexure, and an actuator piece rockably seated under spring tension between the free leg of said how and said operator spring. WALTER VON STOESER.

REFERENCES CITED UNITED STATES PATENTS Name Date Holmes Mar. 9, 1943 Number

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