US2696541A - Circuit breaker - Google Patents

Description

Dec. 7, 1954 w. A. HABERMANN CIRCUIT BREAKER Filed Feb. 19, 1953 INVENTOR. MYZ'Z/yfl United States Patent IRCUI B EAK William A. Habermanu, Detroit, Mich., assignor to BullDog Electric Products Co., Detroit, Mich., a corporatiou of West "irginia Application February 19, 1953, Serial No. 337,705

Claims. (Cl. 200--116) This application relates to circuit breakers generally and discloses an improvement in circuit breakers of the type disclosed in prior Patent 2,385,727, issued September 25', 1945, to E. T. Platz and to that disclosed in Patent 2,611,052, issued September 16, 1952, to E. T. Platz and Russell S. Davis. Disclosed in these patents is a novel type circuit breaker having a push button type operation which is, manually operable successively for opening and closing the circuit breaker contacts. The breaker is automatically operable for opening the breaker contacts upon the occurrence of an overload in the load circuit containing the breaker. The circuit breaker may have a thermal overload type mechanism which includes a bimetal latch member arranged to latch upon an abutment or holding member upon manual actuation of the breaker mechanism to closed circuit position and releasable, automatically or manually, from the holding member when it is desired to move the breaker mechanism to open circuit, or contact separated, position. In this type of circuit breaker the position of the bimetal latch member relative to the holding member determines the amount of overlap of the latching portion of the bimetal latch member. This degree of overlap will in turn determine the amount of warpage which the bimetal latch member will sustain, when subjected to an excessive or overload electric current, before being released from the holding member. It is common commercial practice to give the circuit breaker a rating, which is the normal: load current which it is designed to transmit, expressed in amperes. The breaker must not only carry the rated load but also must interrupt the circuit when the overload exceeds a predetermined percentage of the rated load, or if the overload exists for a certain time interval, theproblem thus presented is to provide meansfor varying the characteristics of the breaker so that it may be made to selectively respond to more than a single set of overload conditions. The problem thus presented mayv besolved by providing means for variation of the amount of overlap of the latch portion of the bimetal latch element of the breaker mechanism so that it will automatically interrupt the circuit when any of several selected predetermined conditions arise. This is accomplished in. the breaker above referred to by the instant invention which provides a simple structure for adjustment of the overlap of the latch portion of the bimetal latch element.

The invention is particularly adapted for use with the circuit breaker disclosed in Patent No. 2,611,052 referred to above.

Therefore, a primary object of the present invention is to provide a novel calibrating arrangement for a circuit breaker.

A further object of the present invention is to provide a calibrating arrangement which utilizes the existing structure of a circuit breaker.

A further object is to provide a calibrating arrangement which is operable from the exterior of the circuit breaker.

A still further object is to provide a calibrating arrangement which is flexible, inexpensive and easily adapted to a circuit breaker.

These and other features of the invention will become apparent from the drawings wherein:

Fig. l is an elevational view with the side removed of a circuit breaker in the On or closed contact position.

Fig. 2 is a sectional fragmentary view as if on line 2,696,541 Patented Dec. 7, 1954 ice 2-2 of Fig. 1, showing a portion of the circuit breaker mechanism and,

Fig. 3 is a partial sectional view of the circuit breaker mechanism as if on line 3-3 of Fig. 1.

Referring to the drawings (Fig. 1), the circuit breaker as disclosed includes a casing 10 composed of a suitable dielectric material and a breaker mechanism substantially the same as that shown in Patent 2,611,052 referred to above. This breaker mechanism includes a handle or operator 11 extending through the top wall 12 of the easing 10. This operator 11 is arranged to be manually actuated successively in a push-push manner to move the breaker to the On and Off positions. Disposed beneath operator 11 and having the upper end seated therein with the lower end engaged in an abutment in the rear wall of casing 10, is an operator spring 13. Thus, operator spring 13 exerts an outward bias upon operator 11 for positioning it preparatory to a successive manual operation. Below operator 11 and arranged to be engaged thereby when the breaker mechanism is in the Oil circuit position, is a translator 14. Mounted on the underside of this translator 14 is an ambient compensating spring member 15 having a bent-up portion 16 which extends through a cut-out portion 17 of translator 14. A contactor 18 has secured to it as by a rivet 22 a bimetal latch member 19 and is comprised of a movable contact 20, an intermediate body portion 23, and a tail guide 21. A flexible conductor 34 completes the circuit then through bimetal latch member 19. Rivet 22 extends through a journal (not shown) in the translator 14 thereby securing these elements in a pivotal relationship and transmitting circuit closing force applied to operator 11 through translator 14 to contactor 18. The upper end of bimetal latch 19 has a turned down latch portion 23 (Fig. 3) which engages abutment 29 formed in translator 14 for holding the breaker mechanism in the On circuit position. Disposed in the casing 10 and having a portion extending through the rear wall thereof, is a fixed contact 24. A mainspring 26 has its lower end seated in a recess 25 of casing 10 and its upper end surrounding a spring lug 27 extending from the side of the tail guide 21 of contactor 18. This mainspring 26 has an inward force component which biases contactor 18 against translator 14 and also counterclockwise about rivet 22 to move the mechanism to open circuit position upon manual or automatic release of bimetal latch member 18 from abutment 29 of translator 14. This mainspring 26 also exerts a contact closing bias when it is desired to move the breaker mechanism to closed circuit position. The inward component forces bimetal latch member 19 inwardly so that the latch portion 28 of this member will engage behind abutment 29 of support plate 14 when the breaker mechanism is actuated to the closed or On circuit position. Tail guide 21 is also responsive to the inward force of mainspring 26 and is positioned relative to the translator 14 when the breaker is in the On circuit position (Figs. 1, 2, 3) by its contact with the bent-in portion 16 of the ambient compensating spring member 15. The tail guide 21 and the bimetal latch member 19 being rigidly secured together, the position of this bimetal latch member 19 is also determined relative to translator 14. The amount of overlap of the latching portion 16 of the bimetal latch member 19 is thus fixed. Because of the resilient nature of the ambient compensating spring member 15 the inward deflection of the tail guide 21 is variable resulting in a variable degree of overlap of the latching portion 28 of the bimetal latch member 19. To accomplish this variation, a calibrating screw 31 of suitable insulating material and having a necked down portion 32 extending into the lower end of mainspring 26 and a bearing plate 33 abutting the lower end of mainspring 26 is inserted into a tapped hole in the lower wall 32 of casing 10 (Fig. 1). From the above description it can be seen that an inward or outward movement of calibrating screw 31, (when the circuit breaker is in the On circuit position), will vary the compression force of mainspring 26. The inward component of this compression force will deflect tail guide 21 in its abutting relationship with the bent-in portion 16 of ambient compensating spring member 15 (Fig. 2). As the position of tail guide 21 is varied, the position of bimetal latch member 19 is also varied. This variation in turn results in a variation in the amount of overlap of the latch portion 28 (Fig. 3) of bimetal latch member 19 with respect to abutment 29 on translator 14. Once the amount of latch overlap is determined to permit the breaker to open upon the occurrence of the selected predetermined overload conditions, it is a simple matter to so adjust the calibrating screw to achieve the desired result.

As noted, also, in the above description, the function of the ambient compensating spring member is to provide a flexible abutment for the tail guide 21. In circuit breakers not having such ambient compensating spring member already incorporated therein, a spring member may be inserted between the tail guide 21 and the translator 14 which will provide the necessary flexibility to permit variance in the latching overlap. Thus, the invention is not limited to the particular circuit breaker as shown in Patent 2,611,052 but is adaptable to many others.

Now having described the invention herein disclosed, reference should be had to the claims which follow in which we claim:

1. In a thermal overload circuit breaker having a fixed contact and a movable contact with a translator arranged to engage and disengage said movable contact with said fixed contact, a translator resilient member secured to said translator, a carrier for said movable contact having a bimetal latch member arranged to latch upon said translator upon actuation of said contact carrier to closed circuit position, said contact carrier having guide means abutting said translator resilient member for determining the position of said bimetal latch member relative to said translator, a resilient member for providing circuit opening and circuit closing bias for said contact carrier and for determining the position of said bimetal latch member relative to said translator, and means abutting said resilient member for varying the bias of said resilient member whereby said circuit breaker may be calibrated for interrupting an electric current under selected predetermined conditions.

2. In a thermal overload circuit breaker having a fixed contact and a movable contact with a translator arranged to engage and disengage said movable contact with said fixed contact, a translator resilient member secured to said translator, a carrier for said movable contact having a bimetal latch member arranged to latch upon said translator upon actuation of said contact carrier to closed circuit position, said contact carrier having guide means abutting said translator resilient member for determining the position of said bimetal latch member relative to said translator, a resilient member for providing circuit opening and circuit closing bias for said contact carrier and for determining the position of said bimetal latch member relative to said translator, and adjustable means abutting said resilient member for varying the bias of said resilient member whereby said circuit breaker may be calibrated for interrupting an electric current under selected predetermined conditions.

contact and a movable contact with a translator arranged to engage and disengage said movable contact with said fixed contact, a translator resilient member secured to said translator, a carrier for said movable contact having a bimetal latch member arranged to latch upon said translator upon actuation of said contact carrier to closed circuit position, said contact carrier having guide means abutting said translator resilient member for determining the position of said bimetal latch member relative to said translator, a resilient member for providing circuit opening and circuit closing bias for said contact carrier and for determining the position of said bimetal latch member relative to said translator, and screw means abutting said resilient member for varying the bias of said resilient member whereby said circuit breaker may be calibrated for interrupting an electric current under selected predetermined conditions.

4. In a thermal overload circuit breaker having a fixed contact and a movable contact with a translator arranged to engage and disengage said movable contact with said fixed contact, a resilient ambient compensating member secured to said translator, a carrier for said movable contact having a bimetal latch member arranged to latch upon said translator upon actuation of said contact carrier to closed circuit position, said contact carrier having guide means abutting said resilient ambient compensating member for determining the position of said bimetal latch member relative to said translator, a resilient member for providing circuit opening and circuit closing bias for said contact carrier and for determining the position of said bimetal latch member relative to said translator, and means abutting said resilient member for varying the bias of said resilient member whereby said circuit breaker may be calibrated for interrupting an electric current under selected predetermined conditions.

5. In a thermal overload circuit breaker having a fixed contact and a movable contact with a translator arranged to engage and disengage said movable contact with said fixed contact, a translator resilient member secured to said translator, a carrier for said movable contact having a bimetal latch member arranged to latch upon said translator upon actuation of said contact carrier to closed circuit position, said contact carrier having guide means abutting said translator resilient member for determining the position of said bimetal latch member relative to said translator, a resilient member for providing circuit opening and circuit closing bias for said contact carrier and for determining the position of said bimetal latch member relative to said translator, said guide means being adjustably positioned by said translator resilient member to enable said circuit breaker to be calibrated to interrupt an electric current upon the occurrence of selected predetermined conditions.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,035,743 Frank et al. Mar. 31, 1936 2,049,354 Chapman July 28, 1936 2,132,628 Jackson Oct. 11, 1938

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