US3080462A

US3080462A - Circuit breaker

Info

Publication number: US3080462A
Application number: US842333A
Authority: US
Inventors: Robert T Casey
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1954-10-07
Filing date: 1959-09-25
Publication date: 1963-03-05
Anticipated expiration: 1980-03-05

Description

March 5, 1963 R. T. CASEY CIRCUIT BREAKER 2 Sheets-Sheet 1 Fig.

Original Filed Oct. 7, 1954 /NVENTOR. fimfi y March 5, 1963 R. T. CASEY 3,080,462

CIRCUIT BREAKER Original Filed Oct. 7, 1954 2 Sheets-Sheet 2 INVENTOR.

United States Patent 3,080,462 CIRCUIT BREAKER Robert T. Casey, Southington, Conn., assignor to General Electric Company, a corporation of New York Original application Oct. 7, 1954, Ser. No. 460,832, now

Patent No. 2,925,481, dated Feb. 16, 1960. Divided and this application Sept. 25, 195?, Ser. No. 842,333

7 Claims. (Qt. Nth-$) My invention relates to automatic electric circuit breakers, and more particularly to small air circuit breakers of the type used for control of light and power circuits in residential electrical systems. This application is a division of my application Serial Number 460,882, filed October 7, 1954, issued as Patent Number 2,925,481, February 16, 1960, and assigned to the same assignee as the present invention.

Circuit breakers of the type referred to are required to be small in size and inexpensive in cost, and, for ease in installation, are desirably adapted for plug-in mounting. In order to achieve the required low cost, it is desirable that the parts thereof be adapted for assembly by automated means rather than by manual assembly. In addition, such circuit breakers are required to include means whereby automatic interruption of the controlled circuit is achieved by magnetic or instantaneous-acting means as well as by thermal or time-delayed means.

For proper operation, certain types of such circuit breakers also require that the relatively stationary contact thereof be resiliently mounted so that when engaged and depressed by the movable contact, a desired amount of resilient pressure is provided to maintain good contact pressure in operation.

In circuit breaker constructions of the prior art, these objectives have not all been adequately achieved by any single circuit breaker, but in each case, certain objectives are achieved only at the sacrifice of others.

It is an object of the present invention to provide a circuit breaker including a relatively stationary contact a sembly which, (a) is of inexpensive, essentially one-piece construction, (b) provides plug-in line terminal means, (0) provides resilient stationary contact supporting means, (11) provides a source of instantaneous-acting magnetic force for initiating automatic opening of the circuit breaker, and (e) is adapted to be assembled in the circuit breaker by automated means.

In accordance with the invention in one form, I provide an electric circuit breaker comprising a generally rectangular insulating casing having at least one generally planar wall and provided with an opening adjacent an edge portion of such wall. A terminal member is also provided of fiat resilient strip metal, having end portions return-bent on the central portion to form a generally S-shaped member which is adapted to be clipped onto the wall portion by a straight-line movement. The terminal member, when assembled, provides an external portion serving as a plug-in type line terminal, and an inner portion serving to resiliently support a relatively stationary line contact. In addition, the terminal member includes portions which provide additive instantaneous-acting magnetic forces for moving the stationary contact in response to predetermined short-circuit currents.

The invention will be more fully understood from the following detailed description, taken in conjunction with the accompanying drawings, and its scope will be pointed out in the appended claims.

In the drawings,

FIGURE 1 is a side elevation view of an electric circuit breaker embodying the invention, the enclosing casing being shown in section, the side toward the viewer being removed to show the parts, which are shown in the open condition;

3,080,462 Patented Mar. 5, 1963 FIGURE 2 is a sectional view of the circuit breaker of FIGURE 1, taken on the line 22 of FIGURE 1;

FIGURE 3 is a view similar to FIGURE 1, the parts being shown in the closed condition;

FIGURE 4 is a view similar to FIGURE 1, the parts being shown in the condition existing immediately after automatic opening, i.e., with the thermally responsive bimetallic strip in deflected condition; and

FIGURE 5 is an exploded perspective view of portions of the circuit breaker of FIGURE 1.

Referring to the drawings the invention is shown as embodied in an electric circuit breaker including a onepiece open-bottom insulating casing 1 containing a circuitbreaker mechanism as set forth and claimed in my aforesaid patent, which is adapted to be pre-assembled and inserted into the casing 1 through the open bottom wall, which is thereafter closed by means of a generaly L- shaped insulating closure member 40, retained in position by a metallic retaining clip 41.

The operating mechanism assembly comprises a generally U-shaped or bifurcated combination frame and load terminal member 28, having a bight portion 31 and a terminal extension 34.

The member 28 is supported in the casing 1 by having the end portion thereof adjacent the extension 34- supported by the upper end of the closure member 49, and by having its opposite end portions 3 resting against an inner surface of a side wall portion of the casing 1.

The frame member 28 supports a pivot pin 10 which has an elongated bimetallic strip 7 rigidly attached thereto by suitable means, such as by welding. A movable contact 6 is mounted on the opposite end of the strip 7 also by suitable means such as by Welding A latch member 14 is also provided, which is rigidly attached, as by welding, to the end of the bimetallic strip adjacent the contact 6, the assembly comprising the strip '7, contact 6, and latch member 14-, being biased for counterclockwise rotation about the pivot pin 10 by means of tension spring 24, connected between the end of the assembly adjacent the contact 6 and a lancedout eyelet portion 35 of the frame member 28.

The movable contact assembly is adapted to be r0- tated about the pivotal axis of the pivot pin 10 by means of a handle assembly comprising a generally U-shaped metallic handle-supporting member 12 having opposed similar side portions pivotally supported on the pivot pin it between the side portions of the frame member 28, and having its bight portion extended to provide an extension 19 provided with a detent 29 for a purpose to be described.

The handle supporting member 12 also includes extensions or lugs 12a extending in closely fitting relation in recesses in an insulating manually operable handle member 13, having a portion extending through an opening provided in the top wall of the casing 1 for manual engagement.

The insulating handle 13 is provided with an extension 13 adapted to engage a compression spring 26 resting on the bight portion 31 of the frame member 28, by which the handle 13 is constantly biased in a clockwise direction about the pivot pin 10. The handle extension 13' also includes an opening 33 for a purpose to be described.

The handle extension 13' further carries a metallic latch member 32 having upturned end portions fitting into corresponding recesses in the extension 13 and having an opening 32A registering with the opening 33 of the extension 13.

In accordance with the invention, a combination line terminal and stationary contact supporting member 3 is provided comprising an elongated resilient strip of conductive metal having an intermediate portion 50, a first return-bent portion 51, and a second return-bent portion 52, upon which is mounted a relatively stationary contact member 5.

The operation of the invention will be understood by referring first to FIGURE 1, in which the parts are shown in the normal off condition. In this condition, the handle 13 is maintained in its extreme clockwise position by the action of compression spring 26. The movable contact assembly, comprising the bimetallic strip 7 and the latch strut l t, is likewise biased to its extreme clockwise position' by the tension spring 24, the end of the latch member 14 resting on the latch member 32, adjacent the opening 32A.

To ciose the circuit breaker, the handle 13 is moved counterclockwise about the pivot pin it), pressing against the end of the latch 14, and moving the movable contact assembly counterclockwise also about the pivot pin 10, to the closed position as shown in FIGURE 3. When the parts reach the closed position, the detent 29 of the extension 19 engages the fixed pin 30 carried by the frame member 23, thereby retaining the parts in the closed position.

When the parts are in the closed position, a circuit exists through the circuit breaker from the line terminal 3 to the load terminal 34 as follows: from the line terminal 3 to the stationary contact 5, to the movable contact 6,

through the bimetallicstrip 7, to the pivot pin 1i) and through the bearing engagement of the pivot pin 10 to the frame member 28, and thence to the load terminal 34.

Upon the occurrence of a predetermined overload current in the described circuit, the bimetallic strip, which has its high expansion side adjacent the stationary contact, warps so as to assume a convex condition with respect to the right-hand side of the circuit breaker casing as viewed. The result of such warping is to move the latched end of the latch strut 14 toward the pivot pin it When this occurs to a predetermined degree, the end of the latch member 14 drops into the opening 32A, permitting the movable contact assembly to be moved clockwise about the pivot pin 10 by the action of the tension spring 24. As the movable contact assembly moves clockwise as described, the intermediate portion of the latch 14 engages the end'of the extension 19, disengaging the extension 19 from the pin 30, and allowing the handle 13 to be moved clockwise by the action of the. compression spring 26. The parts at this instant, immediately following thermal tripping, are in the condition shown in FIGURE 4. As the bimetallic strip 7 cools and resumes its normal straight condition, the end of the latch i4 is moved out of the opening 32A until it resumes its original latched position as shown in FIGURE 1.

Returning again to consideration of the circuit breaker in the oni position as shown inFIGURE 3, if a short circuit occurs in the circuit controlled by' the circuit breaker, the extremely high current, because of the nature of thecurrent path, exertsv an instantaneous magnetic force on the movable contact in a clockwise direction. This force is transmitted, through the engagement of the latch 14 with the latch member 32, to the handle 13, and by the handle 13 to the extension 19, disengaging it from the pin 30, and allowing the

springs

26 and 24 to move the parts at once to the normal off condition 7 as shown in FIGURE 1.

The magnetic force referred to is generated by reason of the conformation and positioning of the line terminal strip .3. Thus, as is well understood in the electrical art, two conductors which are positioned adjacent each other and which carry current flowing in relatively opposite directions, will experience a force tending to force them It will be observed by inspection of the circuit breaker in the closed or on position of FIGURE 3, that there is provided three pairs of suchclosely spaced oppositeover, arranged so that the magnetic forces generated.

thereby will be additive in their effect on the movable contact assembly in tending to'move it toward open condition. Thus the portions St] and 51 comprise a first pair of such conductor segments; the

portions

52 and 50 comprise a second pair of such conductor segments; and the bimetallic strip 7 and the portion 52 comprise a third pair of such conductor segments. When it is considered that the circuit breaker proper, comprising the insulating casing 1, is rigidly mounted in use, and the portion 51 tightly wedged between a'fixed line conductor, such as a bus car, not shown, it will be seen that all. other portions .mentioned are movable by reason of the resilience of the strip 3 and the relative movability of the movable contact assembly. Thus the magnetic repelling forces generated between each of the pairs of conductor segments mentioned, are additive in their effect on the movable contact assembly;

In addition'to providing theabove-described magnetic tripping action, the construction of the stationary contact supporting strip Sperforrns additional valuable func tions. Thus the return-bend between the

portions

52 and 50 provides a resilient support for the stationary contact 5, which permits it to be depressed by the movable contact 6. The'bend' referred to thereforerprovides the required contact pressure to keep the contacts in tight engagement when the parts are in thenormal on condition, as shown in FIGURE 3. V

In addition, the arcuate construction of the portion of the strip 3 external of the breaker casing provides a resilient contact which is adapted to be tightly engaged with a stationary line conductor such as a bus bar.

Furthermore, and in addition to the above, the line contact assembly comprising the strip 3 and the contact 5 provides an assembly which may be readily assembled on the circuit breaker casing 1 by automated means. Thus 7 the assembly may be assembled on the breaker casing by a simple straight-line movement, being clipped" onto the side wall of the casing and retaining itself in place by reason of its inherent resilience. The assembly of the breaker, following the insertion of the mechanism assembly and the stationary contact assembly, is completed by straight-line assembly of the insulating closure 40 the vertical portion of which is received in the slot 44 of the casing, and the straight-line assembly of the retaining clip 41 by horizontal movement, during which its return-bent flanges 47, engage the beads 42 of the casing 1. The clip 41 is retained in place without further assembly operations by the inwardly bent corners 47a seating in the notches 46 in the beads'42. 1

It will be readily apparent that modifications of the invention may be made by those skilled in the art, and I therefore intend by the appended claims tocover all such modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is: a

1. In-anelectric switching device, a, generally rectangular insulating casing having side walls and a bottom wall, an opening in said bottom Wall extending to the meeting line of said bottom wall and one of said si'de walls,ran elongated terminal memberv of flat resilient strip metal having portions adjacent the opposite ends thereof returnbent on the central portion thereof to form a generally S-shaped member, said terminal member being adapted to be mounted on said one side wall by frictional engagement between one of said return-bent portions and said central portion with said return-bentportion on the outside of said casing, ajfirst contact surface, adjacent the end of said one of said return-bent portions, for connection thereof to an external conductor, and an electrical contact surface adjacent the end of the other of said return-bent portions for cooperation with a movable con-' tact within said casing and insulatingmeans closing said opening in said bottom wall and retaining said terminal in said mounted position.

2. In an electric switching device an insulating casing, a relatively stationary contact in said casing, a generally S-shaped one-piece terminal member of flat resilient strip metal having a first portion within said insulating casing and a second portion extending through a wall of said insulating casing to the exterior thereof, said first portion being generally U-shaped and carrying said relatively stationary contact on the free end thereof, said second portion extending along an exterior surface of said wall generally parallel thereto so as to present a substantial contacting surface available for connection to an external conductor.

3. An electric circuit breaker comprising a contact member movable between on? and on positions, latch means for releasably retaining said movable contact member in said on position, said latch means being releasable upon the occurrence of a predetermined force upon said movable contact in contact-opening direction, a relatively stationary contact disposed to be engaged by said movable contact when in said on position, means supporting said relatively stationary contact comprising electric current responsive means for moving said relatively stationary contact in a direction to exert a force upon said movable contact member in said contact opening direction.

4. An electric circuit breaker comprising a contact member movable between off and on positions, latch means for releasably retaining said movable contact member in said on position, said latch means being releasable upon the occurrence of a predetermined force upon said movable contact in contact-opening direction, a relatively stationary contact disposed to be engaged by said movable contact when in said on position, means supporting said relatively stationary contact comprising electromagnetic force generating means for moving said relatively stationary contact in a direction to exert a force upon said movable contact member in said contact opening direction.

5. An electric circuit breaker comprising a contact member movable between 011 and on positions, latch means for releasably retaining said movable contact in said on position, said latch means being releasable upon the occurrence of a predetermined force upon said movable contact in contact-opening direction, a relatively stationary contact disposed to be engaged by said movable contact when in said on position, means supporting said relatively stationary contact comprising an elongated terminal member of flat resilient strip metal having portions adjacent the opposite ends thereof return-bent on the central portion thereof to form a generally S-shaped member, said relatively stationary contact being mounted on one of said ends of said elongated terminal member, whereby magnetic forces generated in said terminal member short circuit currents exert a force upon said movable contact member to move it toward said ofi position.

6. An electric circuit breaker comprising an insulating casing, a movable contact member within said insulating casing movable between on and off positions, latch means for releasably retaining said movable contact member in said on position, said latch means being releasable upon the occurrence of a predetermined force upon said movable contact in contact-opening direction, a generrally S-shaped elongated terminal member of fiat resilient strip metal having a U-shaped portion Within said insulating casing and a second portion extending outside of said insulating casing, whereby electro-magnetic forces generated in said U-shaped portion of said terminal member act on said movable contact member to move it in a contact-opening direction.

7. An electric circuit breaker comprising a contact member movable between oil and on positions, means for releasably retaining said movable contact member in said on position, said means being releasable upon the occurrence of a predetermined force upon said movable contact in contact opening direction, a relatively stationary contact disposed to be engaged by said movable contact when in said on position, means supporting said relatively stationary contact comprising electric current responsive means for moving said relatively stationary contact in a direction to exert a force upon said movable contact in said contact opening direction.

References Cited in the file of this patent UNITED STATES PATENTS 1,491,799 Haywood Apr. 29, 1924 1,497,241 MacGonigal et a1. June 10, 1924 1,738,140 Despard et a1. Dec. 3, 1929 2,037,570 Torsberg Apr. 14, 1936 2,182,140 Frank Dec. 12, 1939 2,186,251 Lindstrom Jan. 9, 1940 2,546,016 Sandin et a1 Mar. 20, 1951 2,623,967 Herman et a1. Dec. 30, 1952 2,626,335 Landin Jan. 20, 1953 2,632,826 Titus Mar, 24, 1953 2,669,613 Despard Feb. 16, 1954 2,841,673 Benander July 1, 1958 2,856,492 Heyhal Oct. 14. 1958

Claims

7. AN ELECTRIC CIRCUIT BREAKER COMPRISING A CONTACT MEMBER MOVABLE BETWEEN "OFF" AND "ON" POSITIONS, MEANS FOR RELEASABLY RETAINING SAID MOVABLE CONTACT MEMBER IN SAID ON POSITION, SAID MEANS BEING RELEASABLE UPON THE OCCURRENCE OF A PREDETERMINED FORCE UPON SAID MOVABLE CONTACT IN CONTACT OPENING DIRECTION, A RELATIVELY STATIONARY CONTACT DISPOSED TO BE ENGAGED BY SAID MOVABLE CONTACT WHEN IN SAID ON POSITION, MEANS SUPPORTING SAID RELATIVELY STATIONARY CONTACT COMPRISING ELECTRIC CURRENT RESPONSIVE MEANS FOR MOVING SAID RELATIVELY STATIONARY CONTACT IN A DIRECTION TO EXERT A FORCE UPON SAID MOVABLE CONTACT IN SAID CONTACT OPENING DIRECTION.