US1564016A - Electric switch - Google Patents

Description

[N VEN TOR .4 TTORNE Y S Dec. 1 2

' 19 5 B. c. PERKINS vELECTRIC SWITCH Filed Nov. 4, 1.922

` EENJvqM/N C. PERK/Ns By L/WWM Patented Dec. 1, 1925.

UNiTEo STATES PATENT oFF-ICE.

BENJAMIN C. .'PIERKINS, OF HARTFORD, CONNECTICUT, ASSIGNOR TO THE ARROW ELECTRIC COMPANY, OF HARTFORD,

NECTICUT.

CONNECTICUT, A 'CORPORATION OF CON- ELECTRIC SWITCH.

Application led'November 4, 1922. Serial No. 599,015;

fo all whom, z''may concern.'

Be it known that I, BENJAMIN C. PER- KINS, a citizen of the United States of America, residing at Hartford, in the county of Hartford and State of Connecticut, have invented certain new and useful Improvements in Electric Switches, of which the following is a specification..

vMy invention relates to electric switches, and particularly to switches of the rotary snap type. Thev object of my invention is to provide an improved operating spring for the switch mechanism.

In the accompanying drawings y Fig. 1 is a broken side elevation of a switch in which my invention is illustrated in one form;

Fig. 2 is a broken plan thereof;

Fig. 8 is a sidev elevation ofthe spring detached; and v Fig. 4 is a plan view of the Spring.

In switches of the rotary snap type, the standard. mechanism includes a coil spring ot' uniform diameter throughout its length, surrounding the switch spindle and having one enld of the spring secured to the spindle or to some abutment element rotating therewith, while the other end of the spring engages the rotary switch blade or an associated member. An escapement device is generally provided which retains the switch blade during a partial :rotation of the spinm dle, accompaniedy by a correspondingincrease in the torsional stress ofl the spring. Upon release Aot the escapement, the switch blade' moves to its succeeding position with a lsnap action. In order to obtain sufficient strength and ease of action in the spring, it has been necessary to make it of considerable length. In switches for controlling relatively heavy currents, suoli as are employed in heater' installations, the necessaryflength of the spring has often proved a serious handicap by reason of the necessarilv increased length of the s indle to accommodate the spring, thus ren ering the switch as a whole much larger than is desirable, bothfrom tlie standpoint of ap'- pearance and from the standpoint of efticiency, since the lengthened spindle iinposes additional strains upon its bearingl 1n the base, and consequently renders the construction more Subject to yinjury by blows upon the handle end of the spindle. The present invention provides an operating spring which is not only extremely compact, but of such construction that it is possible to provide in a greatly restricted space, a considerably greater length of spring wire, with consequent increased strengthand durability, and freedom from the danger yof over-stressing on operation of the switch.

In the accompanying drawings, I have illustrated a rotary snap switch` of the heat` `er type, comprising an insulating base 5, .upon which thekswitch mechanism' is mounted. The mechanism includes a rotary switch spindle 6 adaptedv to be rotated by issthe thumb piece 7, either in one direction alone or in opposite directions, depending upon the nature of the escapement mecha` nisin, not show-n. Freely mounted on the spindle are switch blades 8, ofwhich two are here shown, although either more or less may be used, depending upon. the service which the switch is toperform. Rigidly associated with the switch blades is a spring abutment plate 9 having an oifl set lug 10. Rigidly secured upon the spindle is a spring abutment plate 11, also having an offset-lug 12. As shown, the lug4 12 -is spaced a less radial distance from the spindle 6 than the lug 10. The' moving parts of themechanism, with the exce tion of the. thumb piece 7, are housed witliin the usual cover 13 provided with an insulating lining 14 in a manner well under-l stood in the art.

Arranged upon the spindle 6 is the coilspring 15, to'which my invention particularly relates. As will be noted, the s ires of this spring instead of being of equa diameter throughout, are of unequaldiaineter, and are spaced fromeach other radially instead of longitudinally, as has hereto ore been common practice. The spircs at the opposite ends of the spring are prothereon by their engagement between the spring ends.

In the particular forni of the spring shown, the spire 18 from which the offset end 17 extends, is ot' greater diameter than the next adjacent spire 19, which again is of greater diameter than the succeeding spire 20, which finally merges in an inner spire 21, i `which is continued by a spire 22 of'mci'eased diameter, substantially corresponding to that of the -spire 20, while the spire 22gin turn merges into the spire 23 of greater diameter, and thelatter finally rinto the spire 24, which is of a diameter substantially corresponding to that of the spire 18. While the vspires are to a certain extent nested, they lie in slightly spaced planes, so that in effect they present in side elevation the appearance of a double cone spool, the apex angle of the cones of which is obtuse. in which the inclines of the cone meetat an angle greater than 90 degrees, since this provides a spring of extremely short axial length, and thus enables me to materially shorten the length of the spindle 6, while at the same time obtaining a spring length fully as long as, if not longer than, that of the usually one-diameter switch spring.

The operation of the spring is substantially identical with that of the usual coil spring. Thus, when the spindle 6v is rotated by the thumb piece 7, the lug 12, which forms the movable abutmentrigid with the spindlev 6, engages one or the other of the ends 1G or 17` of the spring and shifts it cireumt'erentially with respect tothe other n spring end, which is detained by its engagement with the abutment lug 10 rigid with the rotary switch blade. The spring is thus placed under increased torsional stress and effects therotation of the switch blades in the usual fashion upon the release ot the escapement which detains the blades.

I have found that the winding-up action of the spring incident to the rotation of the switch spindle does not materially decrease the diameter of the innermost spire 21 of the spring, suoli reduction of diameter as vis occasioned by the winding action being confined almost entirely to the spires of larger diameter. There is thus no danger that the spring will bind upon the switch spindle. Moreover, due to the enlarged diameter of the end spires of the coil, and

the easier curve thereof, a spring wire ofgreater cross section may be used than has heretofore been possible. spring of greater strength may thus be used. This is important in Yconnection with multi-blade switches, or switches of large size, in which the load imposed u on the spring is often considerable, while 1t is particularly necessary to obtain a rapid snap action in break- Iing the currents which such large switches I prefer a spring are intended to handle.

It will of course be realized that the particular construction of the abutments 10v and 12 may be widely varied. Similarly it is not necessary that the spring be in the shape of a double-cone, since it may suice in some instances to use but a single cone. In such case the end of the spring associated with the spire of least diameter may be secured directly to the spindle 6. I prefer, however, the double cone shape illustrated. The number of spires may of course be varied to meet the requirements of the particular switch in which the spring is installed.

lVitli the understanding that the drawing and foregoing descriptin present but a single illustrative embodiment of my invention, I claim- 1. A coil spring for an electric switch or the like, comprising a double cone torsion spring the terminal spiies of which are of greater diameter than the intermediate spires, the spire of least diameter having an internal diameter sufficient to freely accommodate the switch spindle, the terminal spires of the spring having o'set ends adapted under torsional stress to straddle and engage between them a pair of abutinents relatively pivoted coaxial with the spindle, and angularly displaceable with respect to each other to place the spring under increased torsional stress.

2. The combination with a rotary spindle, of a double cone torsion spring threaded thereon and having its opposite ends offset outwardly away from the spindle, a member Arigid vwith the spindle and having an abutment member engaged under stress between tlie. offset ends of the spring, together with a member pivoted on the spindle and having an abutment element engaged between said ollset ends ot' the spring and held thereby under normal conditions in substantially radial alignment with the abutment member rigid with the spindle.

3. At torsion spring for an electric switch comprising a spring wire'coiled to form a double cone spring with nested spires, the coil of leastdiameter forming the common apex of the cones and spacing longitudinally apart the next adjacent spires of greater diameter of the opposed cones the end spires of said spring terminating in oliset outwardly extending ends adapted to embrace between them, when the spring is under slight torsional stress, relatively movable abutmeiits pivoted substantially coaxially with the spring;

In testimony whereof I have ,signed my y naine to this specification.

BENJ, G. PERKIN S.

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