US2660651A - Electric switch - Google Patents

Description

3 Shettg-Sheet 1 Filed July 26, 1952 Nov. 24, 1953 A. M. DAILY ET AL 2,660,651

ELECTRIC SWITCH Filed July 26, 1952 3 Sheets-Sheet 2 l Msrvm -zzsman A. M. DAILY ETAL. 2,660,651

ELECTRIC SWITCH Nov. 24, 1953 3 Sheets-Sheet 5 Filed my 26, 1952 Patented Nov. 24, 1953 ELECTRIC SWITCH Arthur M. Daily and Mervin B. Arisman, Elkhart, Incl., assignors to Chicago Telephone Supply Corporation, Elkhart, Ind., a corporation of Indiana.

Application July 26, 1952, Serial No. 301,116

(Cl. 20L- 55) 8 Claims. 1

This invention relates to electric switches and like the switch of the copending closely related application of Wilkie L. Bush and Arthur M. Daily, Serial No. 255,270, led November 7, 1951, refers more particularly to switches of the type used in radio and television apparatus and generally mounted on the back of a variable resistor to be actuated by the rotatable control shaft of the resistor.

The switch of the said pending application was devised to be compact and still have all the characteristics necessary to satisfactorily handle A. C. of 125 volts at 3 amperes. The present invention achieves an even greater reduction in overall size and still retains all of the characteristics essential to a satisfactory radio and television switch. To more clearly illustrate this point, the switch of the aforesaid pending application is housed within a casing ig of an inch in diameter, but the casing for the switch of the present invention is only l of an inch in diameter. The new switch is thus more than twentyve percent (25%) smaller in diameter and approximately thirty-eight percent (38%) smaller in area than the earlier switch.

Another purpose of this invention, and which may be considered the dominant force in directing the efforts which resulted in this invention, is to provide a switch in which the amount of material required, especially metal, is reduced far below that heretofore necessary.

Those skilled in this art know that one of the prerequisites of a successful switch for radio and television use is wiping action between the contact surfaces during opening and closing of the switch. The switch of this invention not only has such wiping action but through novel arrangement of the contacts obtains maximum wip ing action with a relatively small opening and closing movement of the contacter.

Another object of this invention is to provide a switch of the character described wherein the contacter is free to adjust itself to the contact surfaces of the stationary contacts.

With the above and other objects in view, which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the herein disclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate two lit complete examples of the physical embodiments of the invention constructed according to the best modes so far devised for the practical application of the principles thereof, and in which:

Figure l is a view partially in side elevation and partially in section through a combined switch and variable resistor embodying this invention;

Figure 2 is a perspective view of the switch shown separated from the resistor and having part of its shell or case broken away to better illustrate details;

Figure 3 is a perspective view of the back end of the resistor housing upon which the switch mounts when in position;

Figure 4 is a front view of the switch shown in its closed position and having part of its contact carrier broken away;

Figure 5 is a view similar to Figure 4 but illustrating the switch in its open position;

Figures 6 and '7 are cross sectional views through Figure l on the plane of the line 6--6 and respectively illustrating the contacter in its initial switch closing position and its final switch closing position to graphically depict the relatively great wiping action which is achieved in the switch of this invention;

Figure 8 is a view similar to Figure l but illustrating a slightly modified embodiment of this invention characterized chiey by the fact that the switch and rheostat are housed within a common shell or case; and

Figure 9 is a cross sectional view through Figure 8 on the plane of the line 9 9.

Referring now particularly to the accompany'- ing drawings in which like numerals indicate like parts throughout the several views, the numeral 8 designates the base of the switch which, as is customary, is formed of insulating material and closes one end of a cylindrical stamped metal shell or case 9 to which it is secured by being confined between indentations I0 and an inturned iiange II. An indentation I2 in the shell or case received in a notch I3 holds the base and shell properly oriented.

Mounted upon the base 8 are the stationary contacts I4 of the switch. Each contact and its terminal I5 is a one-piece T-shaped stamping anchored to the base 8 by having its terminal portion I5 passed through the base and staked thereover. The head of the T-shaped contact projects above the inner surface of the base and has its end portions I6 and I'I curved in opposite directions to overlie the switch base at opposite sides of the contact and thus secure the same against tilting.

The holes in the base through which the terminal portions of the contacts pass are disposed at an angle to one another and the convexly curved end portions i6 which are closer together than any other part of the contacts provide the actual contact surfaces with which a contacter IB engages to close the switch.

The contacter f8 is a U-shaped strip of resilient metal of such size and proportions that the legs I9 thereof are spaced apart a distance when free which is substantially greater than the space between the facing convexly curved contact surfaces i6. During switch closure the free ends of the legs I9 are brought into engagement with thc stationary contact surfaces i6, and as best depicted by a comparison of Figures 6 and '7, after the initial Contact ie established switch closing motion continues and as a result a considerable wiping action takes place `between the contacting surfaces. During this time the resilient legs of the Ushaped contactar, 01E course, are flexed toward each other.

The contacter is disposed between the base B and a disc of insulating material 2t which provides a carrier for the contacter. This disc 20 has three holes 2l, 22 and 22' punched therethrough. The latter two holes are directly opposite one another and loosely receive lugs 23 extended from the adjacent edges oi' the legs of the contactor. The hole 2l is substantially centrally located in the disc and is` equispaced. from the holes 22 and 22. This substantially centrally located hole 2t loosely receives a driving lug 24 projecting from the adjacent edge of a pitman 25 by which the carrier disc 2i' is slid edgewise across the top of the stationary oontacts. The opposite ends of the pitre-an are slidably received in diametrically opposite holes 26 and 2l in the cylindrical shell or case 9 and so located that the path of the pitrnan lieson a median plane which is perpendicular to the switch base and bisects the angle between the stationary contacts.

The pitrnan 25 is stamped and formed of sheet metal and one end portion 28- thereof is relatively wide and parallel to the switch base and the carrier disc 29 to which it is directly adjacent. This end portion 2B of the pitman operates in the hole 26 and has shoulders 28 to collide with the cylindrical shell or case 9 and limit switch closing movement of the pitman.

Switch closing movement is imparted to the pitman by a spring 30 encircling the opposite tail-like end portion @If of the piti-nan which slidably passes through the hole 21, the spring 3B being confined between the side of the shell or case 9 and the underside of the lug 24 and an oppositely projecting nange 32. This lian-gc 32 passes through a hole 33 in the back wall 34 of the stamped sheet metal cup-like cover or casing 36 or the rheostat upon which the switch is mounted in the customary manner.

Within the casing I5 the flange 32 has a cam 36 bent up at right angles therefrom and with which a driving lug 31 carried by the rotatable actuator 38 of the rheostat coacts to retract the pitman against the bias of the spring and hold the switch in its open position.

As brmightl out at length in the cfa-pending application, Serial No. 255,270, engagement of the driving lug 31 with the cam 36 is transient, that is, it takes place during only a small angle of the total rotation of the actuator 38 and the rotatable element of the rheostat which it drives. During operation of the switch, and assuming the same to be in its open position shown in Figure 5, in which position it is held by the driving lug 31 engaging the cam 36, clockwise rotation of the actuator 3S causes the driving lug 3l to ride over the peak of the cam. The involun tary manual snap action which takes place as the lug rides over the peak of the cam causes the lug 31 to loe quickly carried around to a point at which it is clear of the cam so that the spring 36 is free to close the switch. During this spring produced closure the resilient legs i9 oi the contactor first come into engagement with the stationary cornzact surfaces in a manner shown in Figure 6 and then, since the spring 3E is considerably stronger than the resilient legs i9 oi the contactor the switch closing movement of the carrier disc ,20 and thc contactor carried thereby is continued until the shoulders 2B collide with the side of the shell or case 5, but during this last amount of switch closing movement the rem'ilent legs of the contactor slide around and continually corne into engagement with new sui"- faces of the stationary contacts.

In this connection it is important to observe that the holes 22-22' in which the driving lugs 23 of the contacter are received are large enough to allow considerable play and thus enable the contacter to adjust itself as required to effect the best Switch closing engagement with the stationary contacts.

It is also important to observe that the hole 22 is large enough to allow some edgewise rocking movement of the carrier disc about the driving lug 24 and so that this freedom of adjust ment of the disc will not be lost in the closed position of the switch. The stop shoulders 29 lie well in advance of the leading curved edge 22?' of the carrier disc.

In that form of the invention shown in Figures 8 and 9 the general organization of the switch is the same as described and many of the details are also the same. Hence, the reference numerals heretofore used will be found to apply in most instances. The chief distinction over the previously described construction lies in the fact that the switch and the rheostat are housed within a common shell or case 46. Consequently. a saving in metai is effected, and to take full advantage of this reduction in metal required, the portion Il of the shell or case which contains the switch is smaller in diameter than the portion 42 in which the rheostat is housed. Use of a single stamped shell or case for both units also reduces the cost of assembly.

Prom the foregoing description taken in connection with the accompanying drawings, it will be readily apparent to those skilled in this art that this invention achieves an unprecedented miniaturization in electric switches suitable for radio and television circuits, and that in so doing it not only effects a valuable saving in space but also greatly reduces the amount of critical material needed for its production.

What we claim as our invention is:

1. In an electric switch having a base of insulating material with spaced stationary contacts thereon and a stamped sheet metal case coacting with the base to provide. a housing for the switch, the stationary contacts projecting up from the switch base and being substantially equispaced at opposite sides of a median plane perpendicular to the switch base and substantially bisecting the stamped metal case: a movable contact carrier overlying the stationary contacts, said contact carrier comprising a flat punched disc of insulat ing material having three punched holes therein, one of which is substantially centrally located and the other two being opposite one another and equispaced from the rst hole; a movable contacter between the base and the contact carrier, said contactor comprising a U-shaped resilient member having resilient legs; lugs on the legs of the U-shaped contactor loosely received in the two opposite holes in the contact carrier holding the contacter assembled with the carrier with the resilient legs of the contacter facing the stationary contacts and engageable therewith upon edgewise movement of the contact carrier in one direction along said median plane; a pitman having its ends slidably received in holes in the opposite side walls of the stamped sheet metal case in line with said median plane and by which the pitman is constrained to reciprocation across the base and above the contact carrier; a driving lug on said pitman engaging in the centrally located hole in the contact carrier; a spring acting on the pitman to yieldingly urge the same in the direction to carry the contact carrier toward switch closed position; an actuator rotatable on an axis normal to the switch base; and means for eiiecting a transient driving connection between the actuator and the pitman through which rotation of the actuator through a predetermined angle retracts the pitman against its spring.

2. A miniature electric switch which is satisfactory for A. C. of 125 volts at 3 amperes. comprising: a small cylindrical stamped sheet metal case; a base of insulating material closing one end of the case; a pair of stationary contacts iixed on the base at opposite sides of and substantially equispaced from a median plane perpendicular to the base and passing diametrically through the side walls of the stamped case, said stationary contacts having convexly curved facing contact surfaces perpendicular to the inner face of the base and closer together than any other part of the contacts: a ilat punched disc of insulating material slidably supported on the stationary contacts, for edgewise movement holes therethrough, one of which is substantially centrally located and the other two being opposite one another and substantially equispaced from the first hole; a U-shaped contactor in the space between the base and the contact carrier having resilient legs spaced apart a distance when free which is greater than the distance between the facing contact portions of the stationary contacts but inclined toward one another so that the contacter may be freely wedged between the stationary contacts; lugs on the legs of the contactor loosely received in said two opposite holes in the carrier so that movement of the carrier in one direction across the base carries the free ends of the contactor into engagement with the facing contact surfaces of the stationary contacts and by continued movement in said direction effects a substantial wiping action between the contacting surfaces; a pitman having pitman and holding it against spring produced movement.

3. The switch of claim 2 further characterized by the provision of a stop abutment on the pitman engageable with the side of the stamped sheet metal case to limit spring produced motion of the pitman, said stop abutment being in advance of the leading edge of the contact carrier to arrest movement of the pitman when the contact carrier is still spaced from the side walls of the case though the resilient legs of the U-shaped contacter have been moved into switch closing engagement with the stationary contacts and a substantial distance therebeyond.

4. In an electric switch: a stamped sheet metal cylindrical case; a base of insulating material closing one end of the case; a pair of stationary contacts mounted on the base and projecting up from its inner surface, each of said contacts being a substantially T-shaped stamping, the head of which has its end portions bent in opposite directions out of the plane of the stamping, and the stem of which passes through a hole in the base, the holes in the base in which the stems of the contacts are mounted being equispaced from a median plane perpendicular to the base and passing diametrically through the cylindrical case and being inclined to dispose the heads of the T-shaped contacts at an angle to one another and to said median plane, the end portions of said heads of the contacts nearest one another being convexly curved away from each other and providing convex contact surfaces, the heads of the T-shaped contacts having their edges lying in a common plane parallel to and spaced above the base; a punched sheet metal disc resting on said edges of the stationary contacts and supported thereby for edgewise sliding movement across the base, said punched disc having three holes therethrough, one of which is substantially centrally located and the other two being opposide one another and substantially equispaced from the rst designated hole; a U-shaped contactor having resilient legs spaced apart a dis- @-.s tance when free which is greater than the space across the base, the contact carrier having three between the facing contact surfaces of the stationary contacts, said contactor being disposed between the base and the punched disc; opposite driving lugs on the legs of the contactor loosely received in said two opposite holes in the punched disc; a pitman having its ends slidably passed through holes in the side wall of the case which holes lie substantially on said median plane so that the pitman is constrained to reciprocation along said plane; a driving lug on the pitman loosely received in the centrally located hole in the punched disc; a. spring acting on the pitman and yieldingly urging the same in the direction to move the punched disc and consequently the contacter toward and into wiping engagement with the facing contact surfaces of the stationary contacts; and means for retracting the pitman against the bias of said spring to open said switch and hold the same in its open positionl 5. The electrical switch of claim 4 further characterized by the fact that the sliding pitman has an elongated tail which forms one end portion thereof and about which the spring is coiled with the spring conned between shoulders at the base of said tail and the side wall of the case; and by the provision of shoulders on the opposite end portion of the pitman engageable with the inner face of the case at opposite sides of the hole through which said end portion of the pitman passes, to limit spring produced motion of the pitman, said shoulders lying beyond the nearest portion of the punched disc so that spring produced movement of the pitman is arrested before any portion of the disc bears against the side wall of the case.

6. In a control device of the character described: a unitary stamped sheet metal cylindrical case having a small diameter inner end portion integrally joined to a larger diameter outer end portion; a rheostat mounted in the larger diameter outer end portion of the case and including an insulating base across the open end of the larger end portion and a rotatable actuator passing axially through the base with its inner end accessible from the interior of the small diameter end portion; a switch base of insulating material closing the open end of the small diamete;` end portion of the case; stationary contacts mounted on and projecting from the inner face of said switch base, said contacts having facing convex surfaces perpendicular to the switch base and equispaced from a median plane perpendicular to said bases and passing diametrically through the case; a contacter slidable across the switch base to and from bridging engagement with said convex facing surfaces of the stationary contacts; a contact carrier slidable across the tops of the stationary contacts and conning the contactor between it and the switch base; a driving connection between the carrier and the eontactor; a pitman having its opposite ends slidably passed through holes in the side wall of the small diameter end portion of the case, which holes lie on said median plane so that the pitman is constrained to reciprocation across the switch base and along said median plane; a driving connection between the pitman and the contact carrier; a. spring surrounding a portion of the pit man and confined between shoulders thereon and the inner wall of the small diameter portion of the case: and means providing a transient driving connection between the rotatable actuator and the pitman inside the large diameter end portion of the case, whereby rotation of the actuator through a small angle oi its total rotation retracts the pitman against the bias of its spring.

7. In an electrical control device of the character described: a unitary stamped sheet metal cylindrical case having a small diameter end portion and a large diameter end portion; an insulaccessible to the space within the small diameter end portion of the ease; an electric switch within the small diameter end portion of the case including a movable contactor; and means for actuating the switch contactor during part of the rotation of the actuator, including a pitman having its opposite end portions slidably passed through diametrically opposite holes in the small diameter end portion of the case; and transiently engageable driving lugs on the actuator and said pitman.

8. In a control device of the character described: a unitary stamped, cylindrical sheet metal case having small and large diameter end portions integrally joined to one another by an intermediate stepped wall portion; a at switch base of insulating material closing the open end of the small diameter end portion of the case; stationary contacts mounted on and projecting from the inner face of said base; a movable contactor slidable across the base to and from bridging engagement with said stationary contacts; a contact carrier constrained to movement across the flat base and the stationary contacts thereon and confining the contactor between it and the switch base; a driving connection between the carrier and the contactor; a pitman having its opposite ends slidably received in diametrically opposite holes in the side wall of the small diameter end portion of the case, said holes being positioned to constrain the pitman to reciprocation along a path parallel to the inner face of the switch base; a driving connection between the pitman and the contact carrier; a spring imposing an endwise thrust on the pitman and urging the same in one direction; an abutment on the pitman projecting into the large diameter end portion of the case; a rotatable actuator mounted in the large diameter end portion of the case and constrained to rotation about an axis perpendicular to the switch base; and a driving abutment on the actuator movable, by rotation of the actuator, in an arcuate orbit 1ying in a plane closely adjacent to the stepped intermediate portion of the case, the abutment on the pitman extending across the path of the driving abutment, and the contacting surfaces of said abutments being so disposed that during rotation of the actuator in one direction the pitman is retracted against the force of its spring.

ARTHUR M. DAILY. MERVIN B. ARISMAN.

No references cited.

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