US2261016A - Switch - Google Patents

Description

y swITcH E. F. CARLSON Filed April 14, 1939 oct. 28, 1941.

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LLMQ. M.

Patented Oct. 28,1941

.Elis F. Carlson, Kenilworth, lll., assignor of onehalt to Oscar F. Carlson Company, Chicago, Ill.,

a. corporation of Illinois, and one-half` Everett N. McDonnell, Chicago, Ill.

Application April 14, 1939, Serial No. 267,754 4 claims, (c1. zoo- 67) This application is a continuation-impart vof the copending application, Serial No. 228,566, filed September 6, 1938, by Oscar F. Carlson and Elis F. Carlson, now Patent No. 2,232,996, issued February 25, 1941.

The object and general nature of this invention resides in the provision of new form of electric switch of the snap action type which when opened separates the contacts yrapidly and produces a wider air gap than previous switches of this type, thus permitting the use of larger contacts and increasing the electrical capacity of the unit. Further, it is a feature of this invention to provide a switch in which only a small movement of theoperating plunger is required to produce the wide opening movement just mentioned. Still,v

further, it is a feature of this invention to provide a light action short movement switch which is compact yet sturdy and rugged.

Another feature of this invention is the provision of a snap action switch in which the required movement of the operating means is small yet positive opening and closing movements are secured with rapidity of action in either direction. Another feature of this invention is the provision of a switch in which a substantial amount of overtravel of the operating member is accommodated, thus .making it possible to permit a continued movement of the switch operating means after the contacts are separated and eliminating disadvantages of having to restrict the switch operating means within close structural or manufacturing limits.

More specifically, itis a feature of this invention to provide a switch unit that includes a pair of contacts, one of which is movable with respect to the other and is carried on a spring arm that normally is held by suitable releasable or yielding means in a position maintaining th movable contact in one position relative .to the other, in connection with suitable actuating means which acts through the spring arm and flexes the same, iirst, to overcome the releasable or yielding means and then to shift the movable contact with a quick or snap action into its other position. Preferably, such releasable or yielding means is in the form of a fixed permanent magnet and an armature on the movable spring arm. An additional feature of this invention is the provision of means for limiting the minimum air gap between thearmature and-the magnet.

These .and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description, taken in conjunction with the accompanying drawing.

In the drawing:

Figure 1-is a longitudinal vertical section taken through the preferred form or switch;

Figure 2 is a section taken 'along the line 2-2 of Figure l; I

Figure 3 is a section takenalong the line 3-3 of Figure l; l

Figure 4. is a fragmentary section taken along l the line 4 4 of Figure 3;` y

Figure 5 is a perspective of one ofthe adjusting screws; y

Figure 6 is a fragmentary section Similar to Figure 1. showing the position of the parts just before contact is broken; and l Figure 7 isa view similar to Figure 5, showing the switch in open circuit' position. y

Referring now more particularly to Figures 1 and 2, the switch of the presentinvention comprises a casing 5 that is made up of abasemember 6 and a coverfl, both preferably formed of insulating material. The base Srincludes atone side thereof a raised portion Baround which the edge of the coverfl fits, and the opposite slidenof the base 6 is also providedwth a raised sectiony which is recessed at I I to vreceive ,terminals referred to below. rThe. cover l of `the switch casing 5 is provided with a boss I3 :which is apertured, as at I4, and receives. an axially shiftable operating plunger I5.. The basesv and'- the cover 'l are'made of insulatingmaterial, anda pair of screws I6 pass upwardlythroughthe,base` and are threaded into tappedopenings'in bossesv Il formed on the cover 1 tosecure the'cover and base together. y, K y o y As best shown inFigure 3,.,the: housing 5 encloses two separatelswitch units jland'la vwhich are arranged alongside one another. but in opposite relation. The switchunits I 8 and ISare substantially identical so that fa descrir'ition.of one will suice, corresponding parts of theftwounits being indicated by the samevreference numerals.

Referring now to Figure 1*,vthe base 6. carries .a stationary terminal 20 'thatincludesa sleeve'ZI to which the horizontal portion 2,2,of abracketi is riveted or otherwise Xed in asuitablemanner.

The sleeve 2| is threaded to receive a screw under the head of which aA flanged terminal washer 26 is disposed. Eziclrwasher has one or more notches 21 to accommodate the Wireor conductor that is fastened bythe screw` 24`` to the terminal 20. The base 6 also carries a stationary contact structure 30 which comprisesa sleeve'i internally threaded to receive a terminal screw `32 substantially identical withthe screw 24 described above. Underneath the head of thek screw' `312 is a ilanged terminal washer 33 having'a conductor y receiving recess 34. Thefsleeve 3| carries an apertures head as in wnicfnajconiact element 3T is fixed, as by being riveted'therein. y,Uiideb neath the head 3B of thesleevevxi is afplate 32 havingV an end 3,9 extending over-the intermediate portion of the small horseshoe magnet l Lthe lat- -ter being seated in arecess'i'orrnedfiri tiieba'se 6 to receive it. The two poles of the magnet 4| are indicated. at 43 and 44 (Figure 2). The

magnet y4| influences a movable switch element element 55 whichv has a shank 56 extending through an aperture in the spring arm 53 and through an aperture in an armature 51 pref--y erably formed of iron, steel or similar metal. The outer endof the latter has a tongue 58 bent overthe outer end of the spring arm .53 to secure the rm attachment of the armature 51 to the outer end of the spring arm 53. As best shown in Figure 5, portions 59 of the armature are pressed into openings-,80 in the arm 53, thereby preventing any relative movementbetween the arm and the armature. The spring arm 53 is made of copper or other non-magnetic material, and has lugs 53a bent downwardly to form stops extending about two-thirds of the distance between the armature 51 and the poles of the magnet 4|. These stops 53a limit the movement oi the armature 51 toward the magnet so that at no time can the air gap between the armature and stop be less than the height of the stops.

The armature 51 is disposed, as best shown in Figure 1,v directly above the magnet 4|, close enough to the magnet 4| so that when the contacts 31 and 55y are in engagement the magnet exerts an appreciable pull on the amature to hold the contacts in engagement until a force is exerted through the spring arm 53 that is sufcient to overcome the pull of the magnet, as

erally in the -plane of the boss I3. A pair of arms 81 and `88 are also pivtally mounted on the pin.8| and formed tolle alongside the sections 84 of the lever 82. Each of the arms 81 and 88 is provided with a laterally extended lug 89 disposed over the bores |4 formed in the cover 1 and engaging the associated operating plunger I5.

Each of the arms 81 and 88 may be fixed in adjusted position relative to the lever 82 independently of the other arm. Each adjusting means includes a cam screw 94 which is best shown in Figure 5. Each cam screw 94 includes a head 95 anda threaded shank 96 formed integrally with and arranged in eccentric relation with respect to the head 95. The lever 82 is provided with two screw threaded openings receiving the camscrews 95, and each cam screw carries a lock nut 91. The head 95 of each of the cam screws is generally cylindrical and is received within an elongated slot 98 formed in each of the .arms 81 and 88. Thus, when the lock nut 91 of will beexplained more fully below, whereupon the contacts 31 and 55 separate with a quick or snap action. The movement of the outer end of the spring arm 53Ais limited by its contact with the abutment portion 1a formed on the casing cover 1.

The means acting through the spring arm 53 to separate the contacts 'consists of a lever 6| which is generallyl U-shaped in section and has an extended portion 62 'engaged by the head of the associated operating plunger |5. The sides of the member 6| are extended'in the form of arms 64 and 65 and 'receive a pivot pin 66 which is supported in a pair of ears 61 and 68 which extend upwardly -from and form a part of the bracket 23. The spring arm 53 passesbetween the arm sections 64 and 65, and the ends of the arm sections 64 and 65 are apertured to rotatably receive the reduced ends of a roller 10 that lies underneath the spring arm 53 adjacent the point where the latter is anchored to the standard 48.

The switch units |8 and |9 may be operated by any suitable means, either simultaneously or alternately as desired.. Where the switches are to be operated alternately a rocker operating mechanism is mounted on the switch case and arranged to engage the plungers I5.

Referring now more particularly to Figure 2, the boss I3 is provided with a central elongated recess11 having two upstanding side walls 18. A pivot pin 8| is disposed in suitable openings in the recess walls 18, and a lever 82 has a portion disposed within the recess 11 and pivotally mounted on the pin 8|. The 1eve r,82 has a recess83 and lateral arm sections 84 disposed geneither cam screw is loosened, the screw may be turned, and due to the eccentric relation between the shank and the head of the screw, turning the screw 95 adjusts the .positiom of the arm relative to the lever. After the arm is adjusted, the lock nut 91 may be tightened to retain the desired adjustment. It will be noted that adjustment of either of the arms 81 and 88 takes vplace aboutthe pivot 8|, which is a pivot about which the lever 82 swings, and that each adjustment is independent of the other.

The operation of the switch described above is as follows:

Any suitable means, such as liquid level, pressure or temperature responsive devices, or any other mechanism, may be arranged to actuate the lever 82, or either or both of the plungers |5. Assuming that the plunger |5 of the switch unit |8 is actuated by any suitable means, the

inward movement of the plunger I5 exerts a pressure on the end of the lever 6|, tending to swing the same in a clockwise direction (Figures 1, 6 and '1) the roller 10 presses upwardly against the spring contact arm 53 closely adjacent its anchored end. However, the magnet 4| exerts a relatively strong pull on the armature 51 that is at the other end of the spring arm 53. This pressure exerted by the roller 18 first flexes the spring contact arm into the position indicated in Figure 6, in which the arm 53 is bowed upwardly -between the roller and the contacts 31 and 55 and the contact 55 shifted-slightly across the con-I tact 31. The corresponding movement of the 'outer end causes the armature 51 to move closer to the magnet 4|`,'and the latter therefore momentarily exerts an even stronger pull on the spring arm 53. The stops 53a prevent the armature 51 from moving so close to the magnet as to prevent the switch from opening. When the continued swinging of the lever 6| bends the spring arm 53 to the precise point where the fiexswitch snaps open with great rapidity, whether the operating means acting through the plunger I4 is itself moved slowly and positively or rela-v tively rapidly. When the pressureonthe plunger I5 is released, the bias of the spring arm 53 causes the same to move toward the magnet 4I, but as the amature 51 moves within the'efl'ective eld of the magnet the latter pulls-the arm 53 downwardly and brings the contacts `3l and 55 into engagement with a snap action, since the pull of the magnet rapidly increases as the armature approaches it. While preferably the stops 53a are lugs formed integrally with the arm 53, they may be separate parts if desired.

It will thus be noted that even if the movement of the operating plunger-I5 is both slow and positively controlled,- as for example by a liquid or metal expansion or contraction dev'lce, the contacts 31 and 55 are, according to my invention, both opened and closed with alquick -snap action.

It will be noted, `particularly from Figure '1, that an additional inward movement of the operating plunger I5 is accommodatedby additional bending of the spring arm 53, 'as indicated by "dotted lines in Figure 7, without damaging or secured by loosening the lock nut S1, turning the screw 98 in one direction or the other, and then tightening the nut 91. If desired, of course, the lever t2 may be eliminated and the plungers I5 operated eithersi'multaneously or alternately, as desired, by any suitable means. The dual switch unit shovm in the drawing, is especially useful for simultaneous or alternate switching of two independent circuits. 1

While I have described my invention as em- 'bodied in a switch of the normally closed type.

it will be seen that, if desired, the spring contact arm 53 may be arranged to be biased to open position and pressed into closed position by the lever 6I or its-equivalent. Thus, a.1sothel contacts will operateV with a snap action, both when engaged and when disengaged just as in the tionary contact member extending upwardly, a.

case of the switch unit shown in Figure 1. Also,

"the spring arm need not be blasted to move into either position, but may be shifted from one position to the other by a lever, such as the lever 6 I, connected with the arm 53 to move it in either direction. In this case, also, the contacts will engage and disengage witha snap action. Other modications of the present invention may be adopted, 4as dened by the appended claims.'`

What I claim and desire to secure by vLetters Patent is:

1. A switch comprising a base, a terminal carsecond terminal and the other `carried adjacent i kmovable contact the outer end of said spring arm, an operating lever pivotally mounted on said bracket and having sections lying on opposite sides of said spring' arm, and means carried by said sections and engaging said spring arm for moving said other contact relative to said one contact.

2. A switch comprising, in combination, a staat' spring arm extending horizontally, means xedly holding one end of said spring arm, a member carried underneath said spring arm at its other end, a, permanent magnet cooperating withv said spring arm for biasing the contact member carried thereby into engagement with said stationary contact memsupport member above said spring arm, andl al rollervcarrled between the depending arms of said operating lever and adapted to engage the underside of said spring arm for moving the same to disengage said contact members.

3. A switch comprising. in combination, an insulating "base, a pair of terminal members carried by said base in spaced relation, a stationary contact member carried by one of said terminal members, a metallic support member secured to the other of said 'terminal lmembers and extending substantially at right angles to said base, a flat spring arm secured at-one end to said support member and extending therealong toward said base for a portion of its length with the remaining portion curved away from said support member and 'extending substantially parallel to saidV base, a movable contact member carried by said remaining portion oi. said spring arm and biased thereby into engagement with said stationary contact member, and operating means reacting against said spring arm adjacent the curved part thereof in a direction away from said stationary contact member for disengaging said movable contact member therefrom.

4. A switch comprising, in combination, an insulating base, a pair of terminal members carried by said base in spaced relation, a stationary contact member carried by one of said terminal members, a metallic support member secured to the other of said terminal members and extending substantially at right angles to said base, a

flat spring arm secured at one end to said support member and kextending therealong toward said base for a portion of its length4 with the remaining portion curved away from said Support member and extending substantially parallel to said base, a movable'contact member carried by said remaining portion of said spring arm and biased thereby into engagement with said stationary contact member, a. pair of ears extend-

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