US2230737A - Electric switch - Google Patents

Description

Fb.4,1941. M, D I j 2,230,737

ELECTRIC SWIITCH Filed Nov. 13, 1959 Inventor: John M- Wl'lde,

His Attorhey.

atented Feb. 4, 1941 OFFICE ELECTRIC SWITCH John M. Wilde, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application November 13, 1939, Serial N 0. 303,971

5 Claims.

My invention relates to electric switches, more particularly to contact .or tip means for electric switches, and has for its object a simple, reliable and inexpensive reversible contact which is arranged to compensate forwear both of itself and of its cooperating contact.

In the construction of electric switches, more particularly contactors in which the switch contacts or tips engage in abutting relation with each other, it is customary to provide for wipe between the contacts. This wipe is defined as the distance the movable contact or tip would move past the position of the stationary contact or tip contact surface if the stationary contact were not there. i

The wipe is accomplished by mounting the movable tip resiliently on a support having a fixed distance of travel so related to the contact tip that the movable tip support is caused to yield resiliently by the engagement of the movable tip with the stationary tip. This wipe causes a rolling or sliding action of the movable tip on the stationary that is beneficial in maintaining clean contact surfaces and in avoiding welding and pitting.

. Normal operation reduces the wipe by mechanical wear and electrical burning. This wear and consequent reduction of the wipe decreases the efliciency of the switch contacts. It is common practice to renew the switch contacts when the contacts have worn to such an extent as to decrease the wine to one-half of its original value.

It will be understood that this wear is quite fast in certain contactors which open and close many times a minute, or even second, during their operation. The contacts are thus the limiting feature in the life of the device. In some applications, the contacts must be renewed on account of wear after a'few months operation.

In carrying out my invention, I provide a switch member having a plurality of contacts or tips and mounted so that it may be easily loosened and moved to bring another contact into working position. This new contact is,.furthermore, constructed to present not only a new unwom contact, but also to ofiset or compensate for the wear on the other cooperating contact which is not renewed. Thus, when the multiple contact member, which preferably is the stationary one, is reversed or reset, the original contact wiping conditions are reestablished.

,For a more complete understanding of my invention, reference should be had to the accompanying drawing, the single figure of which is a fragmentary side elevation view partly in section of an electromagnetically operated contactor embodying my invention.

Referring to the drawing, I have shown my invention in one form as applied to an electromagnetically operated conta tor provided with a base or support It! which p ferably is made of a suitable electrically insulating material such as slate or a moulded compound. Pivotally mounted on this supoprt I0 is an operating shaft having a square portion II to which an arm l2 carrying the movable contact is secured. As shown, the arm I2 is clamped to the shaft by mean? of suitable bolts l3 and I41 The movable contact i5 carried by the arm I2 is a strap of electrically conducting material, preferably copper, having Qrectangular aperture l6 through which extends a rectangular post I! securing the contact to the arm l2, the post I! carrying a helical spring 18 which presses the lower portion of the contact against the arm l2. The upper end of the arm I! is provided with a pivot ridge is, against which the contact I5 rests when the contactor is in the open position shown, and with a second pivot projection 20 in position to be engaged by the lower end of the contact l5, as shown. The lower end of the contact I5 is electrically connected through an electrically conductingcable 2i to a terminal post 22 secured to the base l0.

Secured also to the base It is a support 23 in the form of a strap and made of a suitable elec-- tricaily conducting material. It is secured to the base by screws-24 and 25 and has a lower portion 26 extending outward from the base at substantially right angles thereto. A reversible stationary contact member 21 embodying my invention is mounted on this portion 28 and pivotallysecured to the end of the portion 26 by a screw 22. This contact member 21 is substantially U- shaped, its shape, of course, depending upon the position and shape of the movable contact Ii. The outer faces 29 and 30 of the two upright laterally extending side portions of the member selectively form contact surfaces. As shown, the surface 29 is in position to be engaged by the contacting surface 3| of the contact Ii when the shaft H is rotated in a clockwise direction.

Moreover, the screw 28 engages the base por- Thus, when the screw is tion 30a which is farther away from the pivot 32 55 than the surface 29 in its contacting position. The distance between these two surfaces 29 and 30a is suflicient to offset or compensate for the wear on the contact surfaces 29 and 3|. It is contemplated that the contact 21 will be reversed when the contacting surfaces 29 and 3| have worn sufliciently to take up about one-half of the wipe originally provided. Therefore, the distance between the surface 29 and'surface 30a is made equal to one-half the wipe.

It will be understood that when the shaft II is turned by suitable means, such as an electromagnet, not shown, to close the switch. it is turned considerably farther than the amount required to actually bring the contacts into engagement whereby the wipe is produced. After the two contacts engage, the spring 18 is compressed by the continued movement of the arm l2.

To assure the proper positioning of the reversible contact 21, apertures 33 and 34 are provided in its base on opposite sides of the screw 28 and spaced equidistances from the screw. A coopcrating dowel pin 35 is secured to the support 26 in position to enter one of these holes and thus secure the contact in its correct angular position about the screw 28.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto, since many modifications may be made and I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

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

1. A switch comprising a support, a contact member having a base portion and a plurality of contact portions, and means releasably securing said base portion to said support at a point nearer one contact portion than another contact portion.

2. A switch comprising a support, a contact member having a base portion and a plurality of contact portions extending laterally with respect to said base portion, and means for pivotally securing said base portion to said support at a point nearer one contact portion than another.

3. A switch comprising an electrically conducting support, a U-shaped contact member, and means for releasably securing the base of said contact member to said support at a point nearer one side than the other whereby said contact member can be mounted with said one side in a switching position and thereafter reversed about said pivot to bring the other side into a switching position.

4. A switch comprising a movably mounted switch contact, a support, a stationary contact member provided with a base portion and a contact at each end of said base portion, and means pivotally securing said base portion to said support at a point nearer one of said contacts with said one of said contacts in position to be engaged by said movable contact whereby said contact member can be reversed about said pivot to bring said other contact into position to be engaged by said movable contact.

5. A switch comprising a movably mounted switch contact, an electrically conducting support, a stationary contact member provided with a base portion and a contact at each end of said base portion extending laterally with said base portion, and means pivotally securing said base portion to said support at a point nearer one of said contacts than the other with said one of said contacts in position to be en ed by said movable contact whereby said contact member can be reversed about said pivot to bring said other contact into position to be engaged by said movable contact, and means for. positioning said contact member on said support.

JOHN M. WILDE.

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