US3287522A

US3287522A - Circuit breaker with spring-biased toggle link

Info

Publication number: US3287522A
Application number: US467354A
Authority: US
Inventors: Robert T Casey
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1965-06-28
Filing date: 1965-06-28
Publication date: 1966-11-22
Anticipated expiration: 1983-11-22

Description

"Nov. 22, 1966 R. T. CASEY 3,287,522

CIRCUIT BREAKER WITH SPRING-BIASED TOGGLE LINK Filed June 28, 1965 2 sheets-sheet 1 INVENTOR.

R. T. CASEY Navy 22, 1966 CIRCUIT BREAKER WITH SPRING-BIASED TOGGLE LINK Filed June 28, 1965 2 Sheets-Sheet 2 United States Patent 3,287,522 CIRCUIT BREAKER WITH SPRING-BIASED TOGGLE LINK Robert T. Casey, Southington, Conn., assignor to General Electric Company, a corporation of New York Filed June 28, 1965, Ser. No. 467,354 6 Claims. (Cl. 200116) The present invention relates to improved circuit breakers and more particularly to a novel circuit breaker of the type which may be manually operated to either the open or the closed position and which may be automatically operated to the tripped position in response to an overload in the circuit to which it is connected.

It is an object of this invention to provide an improved circuit breaker which is relatively compact and rugged and which is relatively economical to manufacture.

A specific object of this invention is to provide a simple and compact circuit breaker that utilizes a toggle mechanism with a sliding link biased by a compression spring to position a contact arm pivoted on a releasable member in the open, closed and tripped position.

It has now been found that the foregoing objects and other advantages can readily be attained in a circuit breaker for manual operation during normal use and for automatic operation in response to an overload in the circuit having a housing with a manually operable switch pivoted between its ends on the housing and a releaseable member pivoted on the housing. A fixed contact is supported on the housing, and a contact arm providing a movable contact for engagement with the fixed contact is pivotably mounted for rotation about a point on the releasable member into a closed position with its movable contact in engagement with the fixed contact and into an open position away therefrom. A toggle link between the switch and the contact arm, biased by a compression spring positions the cont-act arm and is manually operable by the switch.

Switch means in the housing responsive to current overload or other means normally holds the releasable member in fixed position but is operable to free the releasable member for pivoting within the housing to move the contact arm away from the fixed contact. A compression spring operating between the switch and contact arm biases the contact arm and the releasable member and cooperates with the switch and a toggle link engaged with the switch and contact arm to provide a toggle with the spring biasing the toggle link to pivot the contact arm into a closed position with its movable contact in engagement with the fixed contact and into an open position spaced therefrom upon operation of the switch.

In this circuit breaker, the toggle link is slidably engaged at one end and pivotably engaged at the other end, with the sliding engagement preferably being provided at the contact arm for ease of construction and assembly and for economy. The switch, slidable toggle link and compression spring form a compact toggle device for biasing the contact arm into the desired position. When the circuit breaker is manually operated to the open position, the line of action of the compression spring is moved across the pivot point of the contact arm so that the arm is biased toward the open position. The force of the compression spring on the contact carryice ing arm also tends to bias the cradle member in a clockwise direction. If an overload occurs while the switch and contacts are in the closed position, the free end of the cradle member will be released by thermally responsive bimetallic stripor other overload responsive switch means and the cradle member will rotate in a clockwise direction. In this manner, the pivot point of the contact arm is moved across the line of action of the compression spring and, as this occurs, the compression spring biases the toggle link which moves the contact arm down and away from the fixed contact. In accordance with conventional practice, the switch means or latch for holding the releasable member in .a fixed position may be any of the types well known in the art and is responsive to a current overload, and it may also be manually operable. The position of the toggle link may be reversed and the same results obtained by having one end of the link pivoted on the contact and its opposite end slidably engaged with the manually operable switch by seating in an aperture or recess formed therein.

The circuit breaker mechanism is constructed so that the parts operate in a relatively small volume because the parts are interfit-ted in a novel and highly desirable manner. The toggle link is disposed within the compression spring, which in turn is partially contained within the legs of the releasable member. Thus, within a relatively small volume all the operating parts are interfitted to form a compact mechanism that is relatively inexpensive to manufacture and efficient in operation.

For a more complete understanding of the invention, reference is now made to the following detailed specification and to the accompanying drawings in which:

FIGURE 1 is a side elevational view partly in section of the circuit breaker incorporating the invention with certain portions of the enclosing casing being removed to show internal construction and with movable elements of the structure being shown in the manually operated open condition;

FIGURE 2 is a view similar to FIGURE 1 with the movable elements being shown in the closed condition;

FIGURE 3 is a view similar to FIGURE 1 With the movable elements being shown in the condition assumed upon operation by an overload current; and

FIGURE 4 is an exploded view in perspective of some of the movable elements of the circuit breaker of FIG- URES 1-3.

Referring now in detail to the attached drawings, therein illustrated is a preferred embodiment of the present invention wherein the circuit breaker has a housing of nonconducting material, generally designated by the numeral 10, with end wall 12 providing a laterally extending shoulder 14 upon which is pivotably mounted the pivot portion 16 of the releasable member or cradle, generally designated by the numeral 18. The pivot portion 16 has arms 20 extending laterally which seat in recesses 22 in the sidewalls 24 of the housing. As best seen in FIGURE 4, the cradle 18 has an extended leg portion 26, a shorter leg portion 27, and a bridging bar portion 28 of which the pivot portion 16 is a part.

Pivotably seated within the notches 30 in the upper edge of the

leg portions

26 and 27 of the cradle 18 are the outwardly projecting fingers 32 at the upper end of the contact arm generally designated by the numeral 34 which is partially surrounded by and rotatable partially within the

legs

26 and 27 of the cradle 18. As best seen in FIGURE 4, the contact arm 34 has a pair of leg port-ions 36 connected by a base portion 38 and a stiffening portion 42 intermediate the length thereof. The base portion 38 carries a movable contact 44 having a slot 46 therein and connected to the flexible cable 48.

Pivotably mounted within an aperture 50 in the end wall 52 of the housing is a switch of nonconducting material generally designated by the numeral 54 and having pivot arms 56 which seat in the sidewalls 24 of the housing 10. Extending outwardly of the aperture 50 in end wall 52 is a manually operable handle portion 58 on the switch 54 which also has an inner end 60 with a recess providing shoulders or recess portions 62 for pivotally seating the arms '64 at the end of the sliding link generally designated by the numeral 66. A compression spring 70 extends about the sliding link 66 and is held by the cross bar portion 68 thereof against the movable contact 44, all partially within the leg portions 36 of the contact arm 34. The sliding portion 72 at the other end of the sliding link 66 slidably seats within the slot 46 in the movable contact 44.

Thus a compact operating mechanism is efliciently and economically constructed by having the sliding link 66 positioned within the compression spring 70, which in turn is partially contained within the leg portions 36 of the contact arm 34, and these parts are all retained partially within the

leg portions

26 and 27 of the cradle 18.

The sliding link 66 and switch 54 form a toggle linkage biased by compression spring '70 for moving contact arm 34 to either the open or the closed position and for moving cradle 18 to the tripped position. When contact arm 34 is rotated from the open position illustrated in FIGURE 1 to the closed position illustrated in FIGURE 2 by manually pivoting handle portion 58 of switch 54 in a counterclockwise direction, the sliding link 66 and the line of action of compression spring 70 are moved across the pivot point of contact arm 34 at the notches 30 on the cradle 18. This rotation of switch 54 causes the toggle link 66 to slide farther into the slot 46 whereby the spring 70 is compressed between crossbar 68 on the sliding link 66 and the movable contact 44 on the contact arm 34. Thus when the toggle linkage is straightened and then buckles in the opposite direction the sliding portion 72 of the sliding link 66 applies force to the wall of the contact 44 at the end of the slot 46 and rotates the contact arm 34 to the closed position illustrated in FIGURE 2.

This action described above is reversed when it is desired to move the contact arm 34 from the closed to the open position. The rotation of the contact arm 34 when moved to the open position is limited by the stop 73 on the sidewall 24 of the housing 10.

The cradle 18 is normally held in the fixed position shown in FIGURES 1 and 2 between the shoulder 14 and the releasable member or latch 74 which has a shoulder portion 76 supporting'the extended leg portion 26. The compression spring 70 biases the contact arm 34 against the cradle 18 at the notches 30 and thereby tends to move the cradle 18 in a clockwise direction about the pivot portion 16 as viewed in FIGURE 1 but is restrained from such movement while the shoulder portion 76 of the releasable latch 74 engages the leg portion 26. The shoulder portion 76 of latch 74 is normally held in the position illustrated in FIGURE 1 by the spring 77 attached to the wall member 79 which biases the latch 74 toward the cradle 18.

The releasable latch 74 has arms 75 at one end thereof pivotably seated in recesses 78 in end wall 52 and may be automatically operated by an overload releasing means such as the current-responsive, thermally actuated, bimetallic strip 80 which will bend away from the releasable latch 74 upon the occurrence of predetermined overload current conditions. The bimetallic strip 80 is connected to the load terminal 82 and to the flexible cable 48. When the bimetallic strip 80 is actuated by an over- 4, load current, it bends and engages clip 84 attached to the latch 74 to move the latch 74 against the bias of the spring 77 and the shoulder portion 76 of the latch 74 is moved away from and releases the extended leg portion 26 of cradle 18.

As the latch 74 is tripped by the movement of the bi metallic strip 80 due to current overload and the cradle 18 is released and rotates downwardly about the pivot portion 16 on the shoulder 14 of the housing 10 where it is supported in the tripped position by the stop 73 on the housing 10, the fingers 32 of the contact arm 34 cross the line of action of the compression spring whereby the toggle linkage formed by the switch 54 and sliding link 66 is straightened and then biased into a buckled position in the opposite direction by the force of the spring 70, moving the contact arm 18 to open to the tripped position illustrated in FIGURE 3. The rotation of the switch 54 moves the handle portion 58 thereof into a straight-up position indicating that the mechanism has been tripped.

The cradle 18 may be reset to the fixed position after tripping has occurred when the bimetallic strip has cooled and the latch 74 has been returned to its normal position by the force of spring 77 by manually rotating the switch 54 in a clockwise direction from the tripped position illustrated in FIGURE 3 to the open position illus trated in FIGURE 1 whereby the inner end 60 of the switch 54 engages the bridging bar portion 28 of the cradle 18 to rotate it upon its pivot portion 16 until the shoulder portion 76 of the latch 74 engages the end of the extended leg portion 26 of the cradle 18 to retain it in the fixed position.

In accordance with conventional practice, the housing 12 also has a line terminal 83 electrically connected to the fixed contact 86 so that when the contact arm 34 is in the closed position illustrated in FIGURE 2 an electric circuit is completed between the line terminal 83 and the load terminal 82 so that current may pass through the fixed contact 86 to the movable contact 44 where it is conducted to the flexible cable 48 and then through the bimetallic strip 81) to the load terminal 82. An arc chute 90 is also provided on housing 10 about the path of the movable contact 48 to and from the fixed contact 86.

Thus, it can be seen that the present invention provides a novel circuit breaker which is relatively compact and rugged and relatively economical to manufacture. The interfitting of parts and the novel assembly with its compression spring provides a highly efiicient structure within a small volume, permitting considerable variation in design and application.

While the invention has been described in only one particular form it will be appreciated that many modifications thereof may be made without departing from the spirit of the invention. I therefore intend, by the appended claims, to cover all modifications as fall within the true spirit and scope of the invention.

1. An electric circuit breaker comprising:

(a) a support;

(b) a stationary contact supported in fixed relation on said support;

(0) a releasable cradle member pivotally supported on said support;

(d) a movable contact member;

(e) means pivotally supporting said movable contact member on said releasable cradle member at a pre determined point;

(f) a manually operable handle member;

(g) means pivotally supporting said manually operable handle means on said support for rotation about a predetermined axis of rotation;

(h) spring means connected between a first point on said manually operable handle member eccentric to said axis of rotation and a second point on said movable contact member spaced from said predetermined point, said spring means urging said first point and said second point apart;

(i) latch means normally restraining said cradle member from rotation about its pivotal support;

(j) current responsive means carried by said support;

(k) means connecting said current responsive means to said latch means, said current responsive means causing release of said latch means upon the occurrence of predetermined current conditions therethrough.

2. An electric circuit breaker comprising:

(a) an insulating casing;

(b) at least one stationary contact supported in said insulating casing;

(c) a releasable cradle member pivotally mounted in said casing at a predetermined pivot point;

(d) an elongated movable contact member pivotally supported on said releasable cradle member at a second pivot point spaced from said first pivot point said movable contact member having a contact surface spaced from said second pivot point for cooperating with said relatively stationary contact, said movable contact member extending to a first side of said releasable cradle member;

(e) a manually operable handle member pivotally supported in said casing at a side of said releasable cradle member opposite from said first side and including a first manually operable portion projecting from said pivot point outside of said casing for manual operation of said switch member and havinga second portion extending in a direction opposite to said first direction;

(f) spring means connected between a first point of said second portion of said manually operable member and a second point of an intermediate portion of said movable contact member and urging said first point and said second point apart and acting through said movable contact member to tend to cause rotation of said releasable cradle member about its pivotal support;

(g) latch means normally engaging and restraining said releasable cradle member from rotation about its pivotal support under the influence of said spring means;

(h) current responsive means connected electrically in series with said stationary and movable contacts; (i) means connecting said current responsive means to said latch means, said current responsive means causing release of said latch means upon the occurrence of predetermined current conditions through said contacts said spring means when released moving said releasable cradle member in a direction away from said manually operable member to move said second pivot point across the line of action of said spring means to reverse the bias of said spring means upon said movable contact member.

3. An electric circuit breaker comprising:

(a) a housing;

(b) a manually operable handle pivoted between its ends on said housing;

(c) a releasable member pivoted on said housing;

(d) a fixed contact;

(e) a contact arm pivoted for rotation about a point on said releasable member and providing a movable contact for engagement with said fixed contact, said contact arm being pivotable into a closed position with its movable contact in engagement with said fixed contact and pivotable into an open position away therefrom;

(f) latch means in said housing normally holding said releasable member in fixed position but operable to free said releasable member for pivoting within said housing to move said contact arm away from said fixed contact;

(g) a compression spring acting between a first point of said manually operable handle and a second point of said contact arm for biasing said contact arm and 6 said releasable member, said spring urging said first and second points apart;

(h) a toggle l-ink engaged with said manually operable handle and contact arm and cooperating with said spring to pivot said contact arm into a closed position with its movable contact in engagement with said fixed contact and into an open position spaced therefrom said toggle link being a normally operable handle.

4. An electric circuit breaker is set forth in claim 3 wherein said toggle link is slidably engaged at one end and pivotally engaged at the other end thereof.

5. An electric circuit breaker for manual operation during normal use and for automatic operation in response to an overload in the circuit comprising:

(a) a housing;

(b) a manually operable handle pivoted between its ends on said housing;

(c) a releasable member pivoted on said housing;

(d) .a fixed contact;

(f) latch means in said housing normally holding said releasable member in fixed position but operable upon current overload to free said releasable member for pivoting within said housing to move said contact arm away from said fixed contact;

(g) a sliding link having one end thereof pivoted on one end of said manually operable switch and the other end thereof in sliding engagement with one end of said contact arm for pivoting said contact arm into a closed position with its movable contact in engagement with said fixed contact and into an open position spaced therefrom, said sliding link being normally operable by said manually operable switch into either of said positions;

(h) a compression spring having its ends operating against said sliding link and said contact arm for biasing said contact arm and said releasable member into an open and closed position.

6. An electric circuit breaker for manual operation during normal use and for automatic operation in response to an overload in the circuit comprising:

(a) a housing;

(b) a manually operable handle pivoted between its ends on said housing;

(c) a releasable member pivoted on said housing;

(d) a fixed contact;

(e) a generally U-shaped contact arm partially enclosed by said releasable member and pivoted for rotation in notches on said releasable member and providing a movable contact for engagement with said fixed contact, said contact arm being pivotable into a closed position with its movable contact in engagement with said fixed contact and pivotable into an open position away therefrom;

(f) switch means in said housing normally holding said releasable member in fixed position but operable upon current overload to free said releasable member for pivoting within said housing to move said contact arm away from said fixed contact;

(g) a sliding link having one end thereof pivoted on one end of said manually operable handle and the other end thereof in sliding engagement with one end of said contact :arm for pivoting said contact arm into a closed posit-ion with its movable contact in engagement with said fixed contact and into an open position spaced therefrom, said sliding link being normally operable by said manually operable switch into either of said positions; and

7 8 (h) a compression spring partially enclosed by said con- 3,110,786 11/ 1963 Glezheizer 200116 X tact arm and partially surrounding said sliding link, 3,171,921 3/1965 Woods. said spring having its ends operating against said slid- 3,201,550 8/ 1965 Leonard 200116 X ing link and said contact arm for biasing said contact Referenees Cited bv the Applicant arm and said releasable member in opposite rotative 5 directions and for biasing said contact arm to open UNITED STATES PATENTS and closed positions, 2,190,517 2/1940 Jennings. 2,214,695 9/ 1940 Jennings. References Cited by the Examiner 2,624,815 1/1953 Gano UNITED STATES PATENTS 10 2,627,563 2/1953 Thomas.

2,688,675 9/1954 Casey. 2,174,232 9/1939 Baker 200-1 16 2 473 4 1949 Baxter 200 116 BERNARD A. GILHEANY, Przmary Exammer.

2,902,560 9/1959 Stanback et al 20088 H. B. GILSON, Assistant Examiner.

Claims

1. AN ELECTRIC CIRCUIT BREAKER COMPRISING: (A) A SUPPORT; (B) A STATIONARY CONTACT SUPPORTED IN FIXED RELATION ON SAID SUPPORT; (C) A RELEASABLE CRADLE MEMBER PIVOTALLY SUPPORTED ON SAID SUPPORT; (D) A MOVABLE CONTACT MEMBER; (E) MEANS PIVOTALLY SUPPORTING SAID MOVABLE CONTACT MEMBER ON SAID RELEASABLE CRADLE MEMBER AT A PREDETERMINED POINT; (F) A MANUALLY OPERABLE HANDLE MEMBER; (G) MEANS PIVOTALLY SUPPORTING SAID MANUALLY OPERABLE HANDLE MEANS ON SAID SUPPORT FOR ROTATION ABOUT A PREDETERMINED AXIS OF ROTATION;