US2400754A - Electric switch - Google Patents

Description

May 21, 1945- C G. M. HAUSLER i` 2,400,754

ELECTRIC SWITCH Filed Jan. 3, 1944 Figi.

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' opposite end of the resilient switch plate.

Patented May 21, 1946 ELECTRIC SWITCH George M. Hausler, Ballston Lake, N. Y., assig'nor to General Electric Company, a corporation of New York Application January 3, 1944, Serial No. 516,753

(Cl. 20D-f6?) 1 Claim.

My invention relates to electric switches, and particularly to overcenter snap-action electric switches having' means for` preventing or inhibiting contact rebound and consequent arcing. The invention is especially applicable to snap action switches of the bridging contact type and provides means for utilizing such a switch as a double-pole single-throw switch, either normally open or normally closed, having its movable contacts permanently connected together.

It is a general object of my invention to provide a simple and reliable snap-action switch of the above character which is adaptable to production in small sizes and in considerable quantity.

It is a further object of my invention to provide new and novel means for inhibiting rebound of a transversely movable snap-action electric contact arm.

It is a particular object of my invention to provide new and novel means for connecting an overcenter electric bridging contact for use as a double-pole single-throw electric switchmember.

By way of illustrating one form which my invention may take, I have chosen to show the invention applied to a snap-action electric switch of the type described and claimed in my Patent 2,332,911, issued on October 26, 1943. As applied to a switch of the type illustrated in the foregoing patent, the invention comprises a relatively light cantilever spring fixedly mounted at one end upon one of the xed contacts and having at its other end a hooked portion bent over loosely to embrace the movable contact member at he is light cantilever spring may be used vas an electric connector to convert the overcenter switch of my prior patent to a normally open or normally closed double-pole single-throw switch with movable tips connected common and known to the trade as a three point switch. The 4light cantilever spring has the further advantage that it substantially entirely eliminates-rebound of the movable contact embraced by the free end of the spring.

For a more complete understanding of my in-` 4 sitions of a snap-action electric switch embodying another form of my invention.

Referring now to the drawing, I have illustrated a push-button actuated snap-action electric switch mounted in a casing IU, lpreferably formed of a suitable molded insulating compound and provided with a removable cover IIla. The

cover Illa may be held in place by one or morebolts Illb shown at Fig. 1. The switch member itself is formed of a unitary flat strip or plate II of spring material slotted at I2 and I3 to provide a pair of outer tension arms I4 and I5 and a central pair of opposing compression arms I6 and I'i. The compression arms I6 and I1 aredeformable and are formed by dividing the central portion of the plate transversely in the region of its center, so that the adjacent inner ends of the anus I6 and I1 are juxtaposed in spaced relation.

At its opposite outer ends the resilient plate II carries a pair of movable contacts I8 and I9.

Two pairs of fixed stop members 20 and 2| are disposed in spaced-apart relation adjacent the movable contacts I8 and I9, respectively, for engagement with the movable contacts to limit their movement in opposite directions transversely of the plate II. At least one of each pairlof fixed stop members 20 and 2l constitutes a xed contact cooperating with the movable contacts I8 and I9. In the form of the invention illustrated in the drawing at Figs. 2 and 3, the upper stop member of each pair of fixed stops is an electric contact member and the lower stop of the pair of stops 2i is likewise utilized as an electric contact. In this particular embodiment of the invention the lower of the pair of stops 20 functions mechanically only and serves no electrical function. In the form of the invention illustrated at Figs. 4 and 5, only the upper stop of the pair of stops 2 I is not used as an' electric contact.

The resilient bridging contact plate Il isl mounted upon an actuating and supporting member comprising a shank portion or rod 30, and at-` tached push-button or head portion 3I and a pair of bowed spring strips 32. The actuating rod 30 is normally biased to its uppermost posi-` tion, as viewed in the drawing, by a compression spring 33. As described in my Patent 2,332,911, the bowed spring strips 32 frictionally connect the push-button 3l to the rod 30 and are notched at their lowerjends to provide y.for pivotal connection to the adjacent inner ends of the compression members I6 and Il. The notched ends of the spring strips 32 thus provide a pivotal supporting and actuating connection between the actuating member` 30, 3|,

32 and the resilient v spring plate or switch member II. 'I'he normal spacing between the pivotal notches at the lower ends of the bowed spring strips 32 is greater than the space between the adjacent ends of the compression members |6 and I1 in the plane of the tension members I4 and I5. Thus, the springs 32 spring 33 and in the other direction by a peripheral flange 36 upon the push-button head 3|. The iiange 32 is arranged to engage a portion of the casing to determine the uppermost limit of movement of the actuating rod 30. It will be understood from my prior patent that overcenter movement of the compression members in one diretion causes the tension members I4 and I5 and the movable contacts I8 and I9 to move with a snap action in an opposite direction and longitudinally of the direction of .motion of the actuating rod.

Referring now particularly to Figs. 2 and 3, I provide a very light or fragile cantilever spring 40 mounted at one end upon the lower fixed contact 2| and extending in substantially parallel spaced relation with the switch plate and into loose engagement with the opposite end of the plate II. Thefree end of the cantilever spring 40 is turned over to provide a hooked or U- shaped end portion 4| loosely embracing the movable contact I8 at the opposite end of the switch plate I I. By reason of the loose connection between the contact I8 and the free end of the spring 40, a. certain degree of lost motion between the spring 40 and the movable contact is provided. The cantileverspring 40 is preferably vformed of silver or other resilient electric conducting material and is appreciably weaker than the spring plate I I.

It may now be observed that with the snapaction switch in the normal position shown at Fig. 2, the light spring 40 is merely interposed between the movable contacts I8 and I9 and the lower fixed contacts 20 and 2 I, thus acting as an auxiliary bridging contact member. When the push-button 3| is depressed, as at Fig. 3, to move the switch member I I upward with a snap-action so that the movable contacts I8 and I9 are brought into engagement with the upper fixed contacts 20 and 2|, the turned-over end 4| of the cantilever spring 40 is interposed between the upper xed contact 20 and the movable contact I8. Thus, the upper fixed contacts 20 and 2| are electrically connected by the bridging contact plate I and are also connected to the lower fixed contact 2| through the electrically conducting cantilever spring 40. The switch illustrated at Figs. 2 and 3 therefore constitutes a normally open double-pole single-throw switch having its movable contact members I8 and I9 permanently .connected together and to the common lower xed contact 2 I.

As illustrated at Figs. 4 and 5, the cantilever leaf spring of my invention may be arranged to transform the snap-action switch illustrated into a normally closed double-pole single-throw switch. For this purpose, the spring B0 is perl stationary contacts 20 and 2|.

manently connected at one end to the upper xed When the pushbutton 3| is depressed to raise the switch plate to its upper position, as illustrated at Fig. 5,

the circuit is broken between the lower stationary contact members and between each of these stationary contact members and the upper stationary contact 20.

The light cantilever leaf spring of my invention serves not only to provide a convenient means for effecting various electrical connections of the snap-action switch illustrated, but functions also to inhibit rebound of the movable contact embraced by the hooked free end of the light cantilever spring. Since the resilient bridging contact plate moves overcenter with a snap action, some rebound of the moving contacts might normally be expected. It has been observed, however, that the leaf spring 4U substantially fully prevents bounce of that moving contact embraced by the free end of the spring. Such non-bounce operation is believed to result from the inertia of the spring 40 and the loose connection between this spring and the moving contact.

The snap-acting switch illustrated in the drawing may be used in still another way to take particular advantage of the non-bounce characteristic of the switch. Referring by way of example to Fig.v 2, le't it be supposed that the lower stationary contact stop 20 is provided with an external terminal connector such as those shown attached to the other contacts. If now, the switch is used simply to make and break the circuit between the lower stationary contacts 20, 2 I, it will be observed that the circuit is made and broken only between the free end of the cantilever spring Ml and the lower stationary contact 2U. The spring 40 is as effective in preventing bounce at the lower contact 20 as at the upper contact 20. Thus, when the switch is used in this manner, arcing is prevented both upon circuit making and circuit breaking operation. The switch of Figs. 4 and 5 could of course be similarly used to make and break a circuit between the upper xed contacts 2|) and 2 In the form of the invention illustrated, only a single cantilever leaf spring is provided, so that rebound of only one movable contact is inhibited. If it is desired to prevent rebound of both moving contacts, an additional fragile cantilever spring l nection, it is sufficient to restrain bouncing of any one of the movable contacts upon opening of the switch in order that arcing be eliminated.

While I have illustrated only certain preferred embodiments of my invention by way of illustration, many modifications will occur to those skilled in the art, and I therefore wish to have it understood that I intend in the appended claims to cover all such modifications as fall within the true spirit and scope of my invention.

What lf claim as new and, desire to secure by Letters Patent of the United States is:

A snap-action electric switch comprising a. base, a resilient plate of spring material slotted longitudinally to provide a plurality of substantially parallel arms connected together at opposite outer ends of said plate, one of said arms being divided transversely intermediate its ends to profor moving said compression. members overeenter with respect to the plane of said plate, a pair of movable contacts carried at opposite ends of said plate, a pair of spaced xed contact members adjacent each of said movable contacts for limiting` transverse movement of said plate in both directions, and a relatively fragile electric conducting cantilever spring mounted at one end upon oneof said xed contact members and being formed at its other-'end to provide a. U-shaped hook portion loosely embracingthe movable contact at the opposite end of said resilient plate, said cantilever spring strip extending in substantially parallel spaced relation to said plate.

GEQRGE M. 'HAUSLERl

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