US2372144A - Relay contact members - Google Patents

Description

March 20, 1945.

T. L. WEYBREW RELAY CONTACT MEMBERS Filed Jan. 28, 1943 INVENTOR 779 e/berf A .h/eybrew In .sa/afz'arz WITNESSES: 22% Z Patented Mar. 20, 1945 RELAY con'raor MEMBERS Thelbert L. Weybrew, Edgcwood, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa.,

Pennsylvania I Application January 28, 1943,

2 Claims. Cl. 200-166) My invention relates,

generally, to relays "and.

more particularly, to contact members for relays which are subject to vibration.

A magnetic-drag relay of the type Patent No. 2,209,368, issued July 30, 1940, to C. C. Whittaker, may be utilized as a speed-indicating and over-speed protective relay on 9. Diesel engine for locomotive service. The overspeed contact members originally provided were of a usual type consisting of one stationary silver button on a screwpost and one movable button on a fiat steel spring. 1 I

:Under normal conditions of operation these contact members remain closed. The circuit through the contact members is opened under an overspeed condition by motion of an insulated end of the relay arm. All Diesel engines vibrate to some extent, the frequency and amplitude varying with the speed and load, and the contact members originally provided were so disturbed by the vibration of the engine that the performance of the relaywas not acceptable.

-1An object of my invention, generally stated, is to provide an improved relay which shall, .be

simple and efficient in operation and'which'may be economically manufactured and installed. I

.g A more specific object of my invention'is to overcome th effects of vibration on the contact members of a relay. 1

Another object of my invention is to provide individual supporting members for relaycontacts which shall have the same natural period of vibration.

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

In accordance with one embodiment of my invention, a pair of cooperating contacts of a relay comprises two duplicate contact spring members each made of a thin metal strip carrying a small contact button. The two contact spring members are so mounted on an insulating base that'the buttons face and bear against each other.v "p'lghe contact buttons do not separate underisevere vibration of varying frequency and amplitude because the two contact springs have the same natural period of vibration and, thereforavibrate in unison.

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

Figure l is a view, partially in elevation and partially in section, of a speed-responsive relay disclosedqin iii relay is utilized;

a corporation of Serial No. 473,82'l

embodying my invention, the contact-actuating arm of the relay being shown in an intermediate position between zero speed and overspeed of the engine or other rotating device with which the Fig. 2 isa view, similar to Fig. 1, with the relay arm in the overspeed position;

Fig. 3 is an enlarged view in plan, of a pair of the relay contact members and their mounting base;

Fig. 4 is an enlarged view, in side elevation, or.

the contact structure shown in Fig. 3; and

Fig. 5 is an enlarged view, in end elevation, of the contact structure.

Referring to the drawing, and particularly to Figs. 1 and 2, the relay shown therein may be of the magnetic-drag type such as disclosed in the aforesaid Patent 2,209,368 which is suitable for utilization as a speed-responsive relay. As described in the aforesaid patent, the relay comprises'a shaft III which supports a rotatable disc (not shown) which is disposed between a pair of rotating magnets (not shown) driven by a Diesel engine or other device with which the relay is utilized. A contact actuating arm I I is securedto the shaft I0 and is normally biased by a spring I2 to a position in which a contact member I3, carried by the arm I I, engages a fixed contact member I4 mounted on an insulating support I5. One

' end of the spring I2 is atttached to an adjustable screw I6 and the other end is attached to an arm H which .is secured to the shaft I0.

As explained in the aforesaid patent, the contact members of the, relay may be utilized to perform switching operations in response to the speed at which the rotating magnets are driven. In accordance with a principle well known in the art, eddy currents are set up in the disc by the flux produced by the magnets and the rotation of the magnets causes a magnetic drag or torque on the disc which is proportional to the speed of rotation of the magnets. When the torque of the disc is suflicient to overcome the biasing force of the spring I2. the contact member I3 is disengaged from the contact member I4 and the arm II is gradually actuated toward the position shown in Fig. 1.

As the arm I I moves from the position shown in Fig. 1 to that shown in Fig. 2 in response to an overspeed condition of the engine, the spring I2 passes overcenter and the arm I I engages the end of a stop member I8. Thus, the arm II is retained in the overspeed position by the spring I2 until the relay is reset by actuating a plunger I9 which pushes the stop member I8 against a com pression spring 2| to actuate the arm l1 past the overcenter position of the spring l2, thereby permitting the arm II to be returned to its normal position. It will remain in this position only if the torque has been reduced by a decrease in speed below that of the overspeed'condition. The relay is provided with a pair of overspeed contacts 22 which are normally closed but which are separated by an insulating member 23 on the arm H in response to the overspeed condition of the engine or other device with being utilized.

In order to overcome the efiects of vibration on the contacts 22, these contacts comprise two duplicate contact spring members 24 and 25"each of which has a small silver button 26 mounted near one end thereof. The other ends of the spring members 24 and 25 are so secured'to an insulating base 21 by terminal bolts 28 and 29, respectively, that the buttons 26 face and normally: bear against each other; he adjustably mounted by' a disposedln a slot 32 base 21.

bolt 3| which is As shown in Fig. 4, the spring'member 25 is ang'ularly disposed on the'base 21, thereby permitting the insulating end 23 of the arm II to en'gagethe spring 24 when the contact arm is in theposition shown in Fig. 2. In this manner the contact buttons 26 are separated, thereby interrupting; the electrical circuit through these Since the two contact spring members 24 and 25 have the same natural period of vibration, they vibrate in unison and, therefore, the contactbuttons 26: do not separate under severe vibration of varying frequency and amplitude. In this manner onepf the defects of the contact arrange ment previously utilized in relays of the present type is overcome, since'the relay isnot afiected by the vibrations of a Diesel engine or similar device. Accordingly, the contacts 22 may be utilized to control-electrical circuits, which will not be adversely affected by the vibration of the'engine and will be interrupted only inrespcnse to which the relay is- The base 21 may provided in one side ofthe indicated by the 0P- ticularly' suitable for use on any relay which is subject to excessive vibration.

From the foregoing description it is evident that I have'provided a simple and inexpensive contact mounting arrangement which is not adversely'afiected by vibration and overcomes the difficulties of previously known relay contact structures.

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 inthe accom panying drawing shall be interpreted as il1ustrative and not in a limitingsense.

I claim asmyinvention:

-1. In a relay, in combination, a pair of coopcrating" contacts comprising two resilient spring members each having a contact member mounted near one end thereof, said endxof each spring member being unattached and free to vibrate, andmeans'for supporting the other ends of the spring members to normally hold said contact members in engagement, the free portions of said spring members being the same length and having the same naturalperiod of vibration, whereby they vibrate in unison.

2. In a relay, in combination, apair of cooperating contacts comprising two resilient spring members each having a contact member mountednear one-end thereof, said end of each spring member being unattached and free to vi"- brate, means for supporting the'other ends of the springmembers, the free portions of said spring members being the samelength and having the same natural period of vibration,.whereby theyvibrate in unison and said contact members are normally held in engagement by said spring members, and means for engaging one of said spring members to separate said contact members.

THELBERT- L. WEYBREW.

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