US2313964A - Electric switch - Google Patents

Description

March 16, 1943. 1 PE C 1- AL 2,313,964

\ ELECTRIC SWITCH Filed July 17, p41 2 Sheets-Sheet 1 'INYENTORS Lawrence Pierce and March 16, 1943.; L. PlERCE E'iAL ELECTRIC swmcn Filed July 17, 1941 2 Sheets-Sheet 2 INVENTORS Lawrence Pierce and John [M Samzeizz/ WITNESISES:

Patented Mar. 16, 1943 ELECTRIC SWITCH Lawrence Pierce, Edgewood, and John W. Samzelius, Forest Hills, Pa., assignors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application July 17, 1941, Serial No. 402,728

2 .Claims.

Our invention relates, generally, to electric switches and, more particularly, to operating mechanisms for switches of the enclosed type, commonly known as safety switches.

In order to increase the life and interrupting capacity of an electric switch, it is desirable to provide a quick-make-and break mechanism for operating the contact members of the switch and ouick-make-and-break mechanisms of various types have been utilized. However, prior quickmake-and-break mechanisms with which we are familiar are complicated in structure and expensive to manufacture, thereby materially increasing the cost of the switch.

An object of our invention is to provide a simple and inexpensive quick-make-and-break mechanism for an electric switch.

Another object of our invention is to provide a quick-make-and-break mechanism which may be readily utilized on an enclosed electric switch.

Other objects of our invention will be explained fully hereinafter or will be apparent to those skilled in the art.

In practicing our invention, the energy necessary to produce the desired quick-break action is unconsciously stored in the hand and arm of the operator, instead of in a spring as in the'usual switch structure, and then suddenly'released before the separation of the contact members takes place, thereby causing the contact members to be opened with a snap-action. Likewise, the operating mechanism functions to close the contact members with a snap-action.

For a fuller understanding of the nature and objects of our invention, reference may be had to the following detailed description, taken in conjunction with the accompanying drawings, in which:

Figure 1 is a View, in side elevation, of a portron of a switch structure embodying our invention, the switch being in the closed position;

' Fig. 2 is a View from the opposite side of the structure as shown in Fig. 1, the switch being in the open position, and

Fig. 3 is a view similar to Fig. 1, with the switch in the open position.

Referring to the drawings, the structure shown therein comprises a portion of a hOllSiIlg I suitable for enclosing an electric switch which may be of the usual type having a rotatable shaft II for actuating one or more contact members l2 into open and closed positions. As shown in Fig. 2, the contact member I2 is carried by an in sulating member l3 which is secured to the shaft l l by a bracket 14.

A manually operable handle [5 is disposed ex teriorly of the housing Ill and rigidly secured to the shaft H for actuating the contact members of the switch in the usual manner. The shaft I I is supported in the housing I0 by a bearing plate I6 which may be secured to the side wall of the housing by rivets l'l.

As explained hereinbefore, it is desirable that the contact members of the switch be opened quickly when interrupting a power circuit, and it is customary to provide switches of the enclosed type with a snap-action mechanism for obtaining the desired quick-break operation of the switch. In prior snap-action mechanisms, lost motion is usually provided between the operating handle and the shaft which actuates the contact members. During the initial movement of the operating handle, energy is stored in a spring which is suddenly released to obtain the desired quick opening of the contact members. Such mechanisms are necessarily complicated in structure and expensive to manufacture, thereby materially increasing the cost of the switch.

In the present structure, since the operating handle 15 is rigidly secured to the shaft II, the motion of the handle and the motion of the contact members are the same except for the small amount of over-travel that is provided in the contact mounting primarily to compensate for manufacturing variations. Therefore, when opening the switch, it is necessary that the handle be accelerated rapidly during the short angular movement corresponding to the over-travel of the contacts in order to obtain the action of a quickbreak mechanism when the contact members separate. To obtain the desired acceleration, the sudden release of some stored up energy is required. The present structure is so made that the required energy is unconsciously stored in the hand and arm of the person operating the switch during the initial stage of operation and then suddenly released before the separation of the contact members takes place.

The foregoing effect is accomplished by securing a cam I8 to the shaft l l and providing a cooperating roller I9 carried by an arm 2| which is pivotally mounted in the housing I0 at a point 22. The cam I8 is provided with a suitable dwell or recess 23 for the roller l9 which is releasably retained in the recess 23 by a spring 24, one end of which is attached to the arm 2| and the other end of which is attached to a bracket 25 secured to the side wall of the housing I0.

The recess 23 is so shaped that the pressure applied on the roller l9 by the spring 24 holds the switch closed against a contact spring 20 and will also hold the switch closed against comparatively weak forces on the handle I5. However, as the force applied to the handle l5 by the operators hand increases the roller is forced out of engagement with the recess 23 and because of the shape of the recess, this will take place with a small angular movement of the shaft. By the time the roller is forced out of the recess all of the resistance against the force on the handle suddenly disappears and the switch is quickly thrown open by the operators hand.

As shown in Fig. 3, the cam 18 is provided with a surface 26 which engages the roller [9 when the switch is in the open position. The surface 26 is so shaped that the tension of the spring 24 retains the switch in the open position until it is closed by the handle I5.

The cam 18 is also provided with a shoulder 21 over which the roller l9 passes as the switch is being closed. The shoulder 2'1 is so positioned that the roller I 9 is quickly forced into the recess 23 by the spring 24 after the roller passes over the shoulder. In this manner the contact members are closed with a snap-action as well as opened.

In view of the foregoing structure, it is prac tically impossible for the operator of the switch to open the contact members of the switch gradually, thereby causing burning of the contact members by maintainin an are between the contact members as they are opened. In order to force the roller I9 out of the recess 23, it is necessary for the operator to apply so much force on the handle [5 that he is unable to check the opening of the contact members when the roller I9 is suddenly forced out of the recess. Accordingly, the contact members are opened quickly and severe burning of the contacts is prevented. Likewise, the contact members are closed quickly by the action of the mechanism herein described.

From the foregoing description, it is apparent that we have provided a simple and inexpensive snap-action mechanism for an electric switch which functions to open the contact members of the switch with a quick-break action in a manner similar to that obtained by more complicated and expensive mechanisms heretofore known and built. The present mechanism may be utilized with an enclosed switch as herein described, or it may be utilized with non-enclosed switches, if desired.

Since numerous changes may be made in the above described construction and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. I11 an electric switch, in combination, a rotatable shaft, a contact member actuated by the shaft to open and closed positions, a handle secured to the shaft, a cam secured to the shaft and rotatable therewith, said cam having a recess therein with sloping sides, a follower disposed in the recess to engage the sides thereof when the contact member is in the closed position, means for releasably retaining the follower in the recess thereby restraining the contact member and the handle in the closed position, and a shoulder on said cam spaced away from the sides of said recess, said shoulder being disposed between the follower and the recess when the contact member is in the open position to cause the follower to pass over the shoulder a predetermined time prior to its entrance into the recess thereby closing the contact member quickly.

2. In an electric switch, in combination, a. rotatable shaft, a contact member actuated by the shaft to open and closed positions, a handle secured to the shaft, a cam secured to the shaft and rotatable therewith, sai cam having a recess therein with sloping sides, a follower disposed in th recess to engage the sides thereof when the contact member is in the closed position, a pivoted arm for carrying the follower, spring means connected to the arm for releasably retaining the follower in the recess thereby restraining the contact memberand the handle in the closed position, and a shoulder on said cam spaced away from the sides of said recess, said shoulder being disposed between the follower and the recess when the contact member is in the open position to cause the follower to pass over the shoulder a predetermined time prior to its entrance into the recess thereby closing the contact member quickly.

LAWRENCE PIERCE. JOHN W. SAMZELIUS.

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