US2688057A - Electrical switch - Google Patents

Description

gfih 1954 s. l. SLATER 2,688,057

ELECTRICAL SWITCH Filed April 18, 1951 "HIM-"- Patented Aug. 31, 1954 ELECTRICAL SWITCH Saul I. Slater, Woodside, N. Y., assignor to Slater Electric & Mfg. 00., Inc., Woodside, N. Y., a

corporation of New York Application April 18, 1951, Serial No. 221,636

1 Claim.

The present invention relates to electrical switches and particularly to toggle switches of the type commonly utilized for installation in lighting circuits of buildings. As is usual in switches of this type the switch is composed of a handle member operating a commutator piece acting in one position as a bridge from one fixed terminal to the other and in another position being idle, the connection between the two terminals being then broken.

In such switches difliculty is encountered in that the terminals, which are resilient, tend to vibrate when the commutator piece snaps into position therebetween. Switches intended tobe used in circuits in which the load is tungsten filament lamps must be designed with the posi-' tive temperature coefiicient of the load in mind. As a result of this load characteristic, the current is very much higher at switch closing than at normal switch opening. In the case of the ordinary 115 volt tungsten type mazda lamps, the initial current is times that of the stabilized current. Thus, in a switch of 10 ampere rating the design is such as to render the switch operable on currents of 100 amperes at closing. The swtich, however, is designed to break a current of only 10 amperes. The 100- ampere flow lasts for only a fraction of a second varying from about a 500th of a second to about a 250th of a second. In prior switches vibration of the terminals upon a sudden impact of the commutator at the instant of make causes breaking of the current at the time when it is at its peak value and resultant burning and pitting of the surfaces of both the commutator and each of the two contact terminals. This, of course, results in rapid deterioration and ultimate inoperativeness of the switch. This vibration has therefore been a major and continuing problem especially in connection with fast acting switches of the toggle type.

It is therefore the primary object of my invention to provide an electrical switch of the toggle type in which the parts are so arranged as to prevent chattering and vibrating of the resilient terminal members thereby eliminating pitting and deterioration of the terminal members and of the commutator member thereby prolonging the life of the switch.

Other objects and features of the invention will be apparent when the following description is considered in connection with the annexed drawings, in which Figure 1 is a vertical cross-sectional view of a switch made in accordance with my invention, the switch parts being in operated or circuit closing position;

Figure 2 is a vertical cross-sectional view of the switch of my invention, the section being taken on the plane of the line 22 of Figure 1;

Figure 3 is a view similar to Figure l but showing the switch in its inoperated or 01f position;

Fig. 4 is a cross-sectional view of the switch,

composed of a body it made of insulating material and ordinarily of a suitable plastic which body is molded to form supports for the operating members of the switch as well as for the fixed terminals. An operating handle H likewise formed of plastic is pivotally mounted in the housing member i0 by means of pins 52 which lie in slots [3 in the housing Iil. Integrally formed with the handle i i is a lug I l which extends within a coil spring iii, the opposite end of which surrounds a projection i6 extending from a commutator member ll. The commutator member I! is also pivotally mounted in the housing, the pivotal mounting being accomplished by having extensions 13 of the commutator member ll extend into slots [9 molded in the body it.

The parts are held in the position indicated by means of a plate 20 fixed to the face of the housing and having inwardly bent portions (not shown) which bear against the pins i2 of the handle -I I. v

Terminals of the shape shown in Figure 5 and designated respectively 2| and 22, are inserted in keyed slots in the housing member as is indicated particularly in Figures 3 and 4. The upwardly extending arms 23 and 24 of these terminal members are inclined inwardly and the entire terminal is formed of somewhat resilient material. These arms or contact portions 23 and 24 of the terminals normally rest against a stop member 25 formed in the shape of a T and extending from the rear portion of the housing forwardly. Projecting inwardly from either side of the housing substantially in line with the bar of the T-shaped member 25 are two stops 26 and 21. These stops cooperate with the T-shaped stop 25 to form small gaps 28 in which the contact arms 23 and 24 are positioned and within which the movement of these arms is limited.

On the side of the housing opposite the T- shaped member 25 there is an inwardly projecting rib 30 which serves to limit the movement of the commutator in one direction, the movement in the opposite direction being limited in the like manner by the bar of the T-shaped member 25.

As will be seen by referring particularly to Figure 2'the commutator. member I1 is .widenthan the distance'between the contact arms 23 and 2.4 when those arms lie against the outer edges of the bar of the T-shaped member 25. Therefore when the handle is thrown into the on.position, the commutator member ll strikes the contact arms 23 and 24, moves themrontwardly against the resilient force exerted by these :arms .and

brings them to rest against the stops 26 and 21.

Due to the stops 26 and 21 and\to .a lesser extent to the preloading of the resilient arms'23 and'24, when the commutator enters between thecontact arms and forces them outwardly to the position shown in Figure 2 and against the, stops .Z-B'and 21, there'can be no vibration of the. contactarms against .the commutator since '.the :contact .arms .bear heavily againstthe commutator: as; it .moves into position and are stoppedinfixed, positions against the stops .26 and 21. Thus-they. arealways prevented from vibrating Withrrespect to the commutator and thereforenoarcin occurs and no resultant pittingof the,contact arm'surface or of the cooperating commutator surface.

Tests have shown that a switch in :accordance with the instant construction, will carry aninrush of current on making contact of IQO-amperesior the first 250th -,to 500th of :asecond-where in ordinary switches this100 ampere. inrush creates extreme arcing because of the usual vibration and chatterin of contacts during the ,make period. The present construction achieves this result because it eliminates the vibration-caused fbreaking of the contacts each time the switch ,is snapped on. This of course-results in ,thematerially lengthened useful life. Theeliminationof chattering in the manner above-described-materially lengthens the life of the switch and, in fact, tests have indicated that the switch .liie well over double that of a similar-switch which is not provided with the stop members .abovedescribed.

Even in those cases wherepdue to the mechanical tolerances allowed, the stops do not fit tightly against the terminalsanda tolerance .of several thousandths of an inch spacing may ,be present between the stop and theterminalwhenithecommutator is in circuit closin position oscillation and vibration of the terminals is substantially stopped due to the fact that the stop interferes with and damps the free vibration of the resilient member. This action may be likened to the effect of placing a solid object close to a vibrating string such as a violin string. The string ceases to vibrate-even though theobject does not touch .the string .whenat rest but merely acts to damp the vibrations thereof.

While I have described a preferred embodiment of the device of my invention, it will be understood that many alterations and modifications :might be made without departing from the spirit .of my invention. I wish therefore to be limited not by the foregoing description but, on the con- .trary, solely by the claim granted to me.

What is claimed is: In an electrical switch of the toggle-operated type having a pair of fixed terminals, and a com- "mutator for entering therebetween to close the circuit,,and in whichthe switch parts are within an insulatinghousing, in combination, a T-shaped. stop member projecting from said housing .and

.extendingbetween the terminals, the terminals .being:formed .of resilient material and normally resting againstsaidstopmember, additional stop members projecting frointhe housing and spaced .from said first-mentioned stop member, one of said second-mentioned stop members being on the opposite side ,of each of said terminals from said first-mentioned stop member thereby forming limit stops for movement'of said terminals in each direction, the commutator beingaclapted to ,enter between said terminals when in circuit- .closing position thereby ,forcing said terminals outwardly against said second-mentioned limit stops, thereby preventing chattering of said resilient terminals as the commutator moves into circuit-closing position.

Images