US2863022A - Circuit breaker - Google Patents

Description

Dec. 2, 1958 D. B. POWELL 2,863,022

CIRCUIT BREAKER Filed April .20, 1955 INVENTOR. DAVID B. POWELL iqwm'w ATTORNEY Unite States Patent CIRCUIT BREAKER David B. Powell, Bristol, Conn., assignor to General Electn'c Company, a corporation of New York Application April 20, 1955, Serial No. 502,693

13 Claims. (Cl. 200-116) My invention relates to automatic electric circuit breakers and, more particularly, to small air circuit breakers of the type used for the control and protection of light and power branch circuits in residential and industrial electrical systems.

One object of my invention is to provide a circuit breaker having a quick make and quick break action, that is, one in which opening and closing movement of the movable contact is not dependent on the speed of movement of the operating handle.

Another object is to provide a circuit breaker having separable butt-type contacts which have a sliding or wiping action before separation and after closing to improve the electrical contact and remove surface impurities.

A general object of my invention is to provide such a circuit breaker which is small, compact, simple in construction and assembly, and inexpensive to manufacture.

Another object of my invention is to provide such a circuit breaker which is simple for the user to operate.

Another object of my invention is to provide such a circuit breaker which indicates its automatically tripped condition by movement of its handle automatically to the off position.

Further objects of my invention will become apparent to those skilled in the art as the following detailed description proceeds.

My invention will be readily understood from the following detailed description taken in connection with the accompanying drawing and its scope willbe pointed out in the appended claims.

Figure 1 is a side elevation view of a circuit breaker made in accordance with my invention, the parts being shown in the normal on or closed-circuit position.

Figure 2 is a sectional view of the circuit breaker of y Figure 1 taken on the lines 2-2 of Figure 1.

Figure 3 is a side elevation view of the circuit breaker of Figure 1, the parts being shown in the off or opencircuit position.

Figure 4 is a side elevation view on reduced scale of the circuit breaker of Figure 1, the parts being shown in an intermediate position which they assume when the handle is moved inwardly from the on position of Figure 1.

Figure 5 is a side elevation view of the casing of the circuit breaker of Figure 1, the parts being removed.

Figures 6a and 6b are side and end views, respectively, of the manually operable handle of the circuit breaker.

In the drawing I have shown my invention as embodied in a circuit breaker comprising a generally rectangular open-sided insulating casing 10 adapted to be closedby a suitable side cover 11 which may be retained by suitable means such as by screws or rivets passing through the openings 12.

For the purpose of connecting the circuit breaker to a circuit to be controlled and protected, I provide a load terminal 13 and line terminal 14. The load terice minal 13 is adapted to be connected to a wire which may be inserted under the head of the screw 13a. The line terminal 14 is adapted to be connected to a source of power by frictional engagement with a suitable stationary connector (not shown) at the surface 14a.

The line terminal 14, comprising a generally L-shaped strap, has one. end portion 14b resting against an abutment 10a of the casing 10, an intermediate portion extending around the pin 15 in the casing 10, and an elongated portion 14d resting at one point against an abutment 10b in the casing 10. An elongated bimetallic strip 16 is rigidly attached to the other end of the terminal member 14 by suitable means such as by welding. A calibrating screw 17 is threadedly engaged in the united end portions of the bimetallic strip 16 and the terminal strip 14. The inner end of the calibrating screw 17 bears against an abutment in the casing 10 and the opposite end is accessible for adjustment from outside the casing 10 through opening 17a. Inward turning of the calibration screw 17 bends the end of the terminal strip 14 downwardly over the abutment 10b, altering the position of the free. end of the bimetallic strip to permit adjustment or calibration. strip 16 has a flexible braid 19 attached thereto by suitable means such as by brazing, and the other end of the braid 19 is similarly attached to one end of the elongated contact arm 20 adjacent the movable contact member 21. The movable contact member 21 is adapted to cooperate with a relatively stationary contact 22 mounted on the load terminal 13.

The electrical circuit through the circuit breaker when in the closed position as, for instance, in Figure 1, may therefore be traced as follows: From the source of power (not shown) to the contact surface 14a of line terminal 14, to one end of the bimetallic arm 16, to the braid 19, to the contact arm 20, to the movable contact 21, to the relatively stationary contact 22, to the load terminal 13, and thence to the load (not shown).

For the purpose of aiding in the extinction of the are formed upon separation of the contacts, I provide an arcing chamber generally indicated at 45 provided with vent portions 46 having fins 4-7 therebetween, preferably integral with the casing 10.

The movable contact arm 20 has one end thereof adapted to be releasably restrained by means of a latch member 23. The latch member 23 is pivotally supported in the circuit breaker casing 10 by means of cylindrical lugs 24 and has a first portion 25 provided with an aperture 26 ,and an adjacent ledge 26' on which the end of the bimetallic strip 16 is adapted normally to latch. The bimetallic strip 16 has its high expansion side adjacent the bottom wall of the breaker. Its free end therefore deflects upwardly upon heating so as to move into the aperture 26, permitting slight rotation of the latch 23 (clockwise as viewed) to the dotted line position of Figure 3. The latch 23 has a second portion 27 adapted to engage the bent-up end portion 28 of the movable contact arm 20 and to restrain it in the on" or closedcircuit position as shown in Figure 1. Latch 23 is provided with a further projection or tongue 44, adapted to be engaged by the corner 28' of the contact member 20 in the process of resetting the circuit breaker, in a manner to be described. The latch 23 is preferably made of one integral piece from which the portions 25, 27, 44 and pivot lugs 24'are formed. The tongue 44, for instance, is preferably formed by lancing out a piece from the portion 25, as shown.

When the bimetal deflects and moves off the ledge 26', the latch 23 rotates clockwise under the bias of contact arm 20 and the end 28 is released from latch surface 27. For the purpose of preventing longitudinal movement of Patented Dec. 2, 1958" The movable end of the bimetallic Z2 thexcontact 8.1111129 prior to release of the end 28 from the latch surface 27, I provide a stop pin ,33 against which the end 28 of the contact arm 20 is adapted normally to bear.

Amain operating;tensionspring 29 has'one end hooked in; an apertured. portion 30 generally centrally of the contact arm: 20 and, the: other endanchoredtoa fixed: In. the on position. of

inner sidewalls provided with an irregularly shaped recess 32(see' Figure 5) and the contact arm20hasxa transversely extendingpin 20a rigidly attached thereto by suitable meanssuch as by welding. The pin 2% .has'

its opposite endsprojecting beyond the sides of-the:con= tact memberzt) and into the recesses 32, so that at cer taintimes the pin 20a has its movements limited by walls' ofthe recesses 32. In addition, the portions of. pin 2041' projecting beyondthe contact arm Ztl but intermediate the contact arm 20 and the extreme ends just mentioned which extend into the recesses 32, are adapted to serve.

as operating abutment portions for thecontactarm 20, and to cooperate with the abutments 4t and thecamzsur faces 39 of the handle 34 in a manner to be described.

Upon deflection of the bimetal 16 and consequent auto-#- matic release of the end 28 of the contact arm 20, the tension spring 29 moves the arm 29 upwardly and to the right until the pin 20a rests in the corner 32a of the recesses32. The spring then rotates the contact arm 20 in a counterclockwise direction about the pin 20a as a pivot, causing the movable contact 21 to move, away from the stationary contact 22.

The handle -is biased outwardly by spring 41, and its outward travel is limited by the engagement of bridgingportion 38with the underside of the contact arm 20.

when the parts are in the position as shown in Figure 3. For the purpose of resetting the contact arm 20 to the relatched and reclosed position, and also for the purpose of manually operating the contact arm 20 to the openv and close. position, I provide a handle member 34 comprising a generally rectangular elongated push rod of insulating material which is slidably supported for reciprocating straight-line movement in the casing by the casing walls and by sides of the bosses. lltlc, d and 110s. Thehandle member 34 is provided with an outwardly accessible. manually operable portion 35 having a marking ring 36 thereon, preferably of contrasting color. The centralpart of the lower portion of the handle 34 is cut away to provide two generally parallel spaced-apart side wall portions 37a and 37b, joinedat their outer extremities by a bridging portion 38; The side wall portions 3761,.and 3712 are provided with cam surfaces 39 and operatingshoulders 4th for, a purpose to be described.

The -handle 3.4 is biased upwardly at all times by'a:biasing spring41'having its body portion encircling the pin 31.and;having one end'resting against an inner wall, of

the casing ltlandits other end resting against an abut-- ment 42.intermediate the side walls 37a andv37b of the handle 34.

With: the .parts in the openposition as indicated in Figure 3, the movement of the handle member '34 outwardly underthe bias of the spring 41 is limited by the bridging, portion: 38 which underlies contact arm 2% When in this position, the marking ring 36 is visible above they-top wall of the-breaker, indicating that the circuit breaker, is in the off or open position. It will be observed that in this position, the shoulders 40 directly overlie the ends of the pin a although a small amount of vclearance exists .therebetween. In order to reclose the circuit breaker, thehandle member 34 is pushed inwardly,

causing-the shoulders 40 to engage the ends of the pin- 2tia,:,moving itinadownwardly direction, the pin,.2tla

the.corners..,formed..by the junctureof shoulder portionv 40 and the vertical portion 48. As downward movement is continued, the forward end 20b of the contact member 20, adjacent the movable contact 21, strikes an abutment 4-3 in the casing 10. Further downward movement of the handle 34 thereafter causes the forward end 2% of the contact arm 2t to slideagainst the abutment 43 and the opposite end 28 of arm 20 to rotatedownwardly in a clockwise direction. As this occurs, the curved portion 28 of the contact arm ZtLengages the bent-over portion 27 of the latch 23 or-the pin 33 (if latch 23 is not in latched engagement withgthe endof bimetal 16) and acts as a cam, forcing the contact member 20 to slide slightly, longitudinally, to the left until restricted by surface 320 of one of the walls of the recess 32 in the casing 1d. The last portion of downward movement of handle member 34 then causes the corner 28 to engage a tongue 44cm the latch member-23 rotating the latch member 23 slightly in a counterclockwise direction against the'inner surface-of portion 141: of the strip Has a stop, and permitting thebirnetal-lic strip into spring to its 'normal'or latched position (assuming that ithas cooled sufiiciently) and-causing the latching end 27 of the latch 23 to again overlie the end 28 of the'contact member 20.

As the -handle 34 is thereafter-released, the main ten* sion spring 29, pulling upwardly and to the right on the intermediate portion of the contact arm 20, biases the end 28of the contact arm 26* against the stop pin 33 in a horizontal direction, and upwardly against the underside oflatchsurface-27 in a vertical direction, tending thereby to rotate the latch 23in a clockwise direction. Such clockwise movement of latch 23 is prevented, however, by the engagement of the end of bimetal 16 with the-shelf 26 of the portion 25. The net effect of the pull of'spring therefore is torotate the contactarm-as a whole about the end'28 as the shoulders 40 permit the pinlda to move upwardly. As this rotation takes place, it will be observed that'the'path ofmotion of the pin-Zi a is along an are centered about the tip of latch 23 and being such as to move the pin Ztla to the left aswell as up wardly. Shortly before the movable contact 21 reaches its final or full on position, the ends of the pin 2% slide off the ends-of the sh0ulders'40, and'the contacts close with a snap action even though the handle is slowly released.

The above description has set forth the automatic opening or"tripping action of'the breaker in going from Figure 1 to Figure 3, and the resetting and reclosing action inreturning from Figure'3 to-Figure 1. The manually operated opening actionand closing action by meansof'the operating member 34 will now be described.

When'theparts are in the closed-circuitposition of Figure 1 and the manually operable handle 34 is depressed, the pin 20abeing'intheleft-hand portion of the recesses 32, is not'engaged by the shoulders' ttb. Instead;

it is engaged by the cam surfaces 39 on the side portions" member 20 out of engagement with the latch surface 27 of the latch'23. Upon release of the latch portion 2 5 from'latch 23', the tension spring 29 is free to rotate the contact arm 20 counterclockwise to separate the contacts Hand 22 with a snap action'independent of the speed of the handle the contact arm going to the position of Figure 4. At the instant of such opening action, the pin 20:; is in contact with the cam surfaces 39 as in dicated .in. Figure 4, and it remains there so long as the handle is held inwardly. Upon subsequent release of the handle 34, thehandleis moved to an upward position by the .handle-returnvspring, while at the same time the tension Spring- 29 tends, to move the contact arm 2011poccurrence of overload conditions.

. ward and to the right. As a consequence, the end of the pin a slides off the cam surfaces 39 and moves into the corner 32a of the recesses 32. The parts, therefore, have returned to the position indicated in Figure 3, from which position latching and reclosing is accomplished in the manner described above.

It will be observed that both opening and closing movements of the contacts of my improved circuit breaker take place with a snap action irrespective of the speed of the movement of the manually operable member. It will be seen, moreover, that the handle need be operated only in a reciprocating manner and only a pushing movement on the handle is required to open the breaker or to close it, even after automatic opening. Furthermore, the open condition of the circuit breaker is clearly indicated by the signal band 36 on the handle 34, the handle being further outward upon opening of the contacts than it is when the contacts are closed, due to the difference in position of the intermediate portion of contact member 2t), which portion acts as a stop for the handle 34. It w1ll be noted, furthermore, that the tripping action takes place irrespective of the maintenance of the handle in the closed circuit position or, in other words, the circuit breaker is trip free.

It is pointed out that although manual opening is accomplished by releasing of a latch engagement, this latch engagement is not the same latch engagement as the trip latch which is automatically released upon the Thus, manual opening of the circuit breaker, even a great number of times, does not cause wear of the trip latching surfaces and therefore the accurate calibration of the circuit breaker is not adversely affected.

By the arrangement of bimetal 16 and terminal strap 14, the action of the bimetal is accelerated on very high overloads by a magnetic repulsion between the bimetal 16 and the adjacent portion 14d of the terminal 14, since the current in these members travels in opposite directions. This magnetic tripping action is sufficient to cause tripping completely unaided on very high short-circuits, and it assists or cooperates with the deflecting action of the birnetal on medium overloads.

It will also be seen that I have provided a circuit breaker which may be used as an alternate action switch wherein a complete cycle of movement of the handle to depressed and released condition results in only one-half cycle movement of the contact member, i. e., from closed to open position or vice versa.

Since many modifications may be made in the form and arrangement of parts of my invention without departing from the scope thereof, I do not wish to be limited to the specific form and arrangement shown, but contemplate rather by the appended claims to cover all such modifications as fall within the true spirit and scope of my invention.

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

1. An electric circuit breaker comprising a manually operable member having a cam surface and an operating surface and being movable back and forth along a predetermined path, a latch, a movable contact member having a latched position in which a portion thereof is in engagement with and restrained by said latch and a tripped position in which said portion thereof is out of engagement with said latch, said contact member having a portion located in the path of movement of said cam surface when said contact member is in said latched position whereby movement of said manually operable member along said path in a first direction when said contact member is in said latched position causes said cam surface to engage said portion of said contact member and to disengage said contact member from said latch, and said contact member having a portion located in the path of movement of said operating surface when said contact member is in said tripped position whereby movement 6 of said manually operable member along said path in said first direction when said contact member is in said tripped position causes said operating surface to engage said portion of said operating member and to reengage it with said latch.

2. An electric circuit breaker as set forth in claim 1 said circuit breaker also comprising a latch movable with respect to the contact member, means biasing said latch in a releasing direction, and current responsive means for causing movement of said latch to said released position upon the occurrence of predetermined electrical conditions in said circuit breaker.

3. An electric circuit breaker comprising a manually operable member having a cam surface and an operating surface, means mounting said manually operable member for reciprocating straight-line movement along a predetermined path, said cam surface and said operating surface describing paths of movement different from each other when said operating member is moved along said predetermined path, a movable contact arm having an operating abutment, a latch, said contact arm having a latched position in which it is in engagement with said latch, means for moving said contact arm and said latch relative to each other when said contact arm is in said latched position to cause disengagement of said latch and said contact arm, means operable upon disengagement of said contact arm and said latch for moving said contact arm from said latched position to an unlatched position, said operating abutment on said contact arm lying in the path of movement of said cam surface and out of the path of movement of said operating surface when said contact arm is in said latched position and lying in the path of movement of said operating surface when said contact member is in said unlatched position.

4. A circuit breaker comprising a vertically and horizontally movable contact member and a rectilinearly reciprocable handle member a latch member adapted to releasably engage a portion of said contact member, said handle member having a cam surface thereon engageable with said contact member for slidably moving said contact member in a direction transverse to the path of movement of said rectilinearly movable handle member and out of engagement with said latch member, means biasing said handle member to move said cam surface away from engagement with said contact member and means carried by said handle member engageable with said contact member for limiting said movement of said handle member.

5. An electric circuit breaker comprising a manually operable member having a cam surface and as operating surface, said manually operable member being mounted for reciprocating straight-line movement, a movable contact member having an operating abutment, said movable contact member being movable in a direction generally parallel to said movement of said manually operable member and said movable contact member also being movable in a direction generally transverse to said path of movement of said manually operable member, said cam surface of said manually operable member being operable to move said movable contact member in said generally transverse direction and said operating surface being operable to move said movable contact member in said generally parallel direction, biasing means biasing said movable contact member against movement in both of said directions, movement limiting means for limiting said transverse and said parallel movement of said contact member to hold said contact member in latched position with said abutment in the path of movement of said cam surface and out of the path of movement of said operating surface, and means for releasing at least a portion of said limiting means to permit movement of said movable contact member under the influence of said biasing means to an unlatched position in which said abutment is in the path of movement of said operating surface.

6. An electric circuit breaker comprising a manually operable member, a movable contact member, said'manuall'y operable member being mounted for reciprocating straight-line movement ina predetermined path, said movable contact member being movable in a first direction generallyparallel to said path of movement of said manually operable member and also movable in a direction generally transverse to said path of movement of said manually operable member, first stop means for limiting said transverse movement of said movable contact member, second stop means. for limiting said parallel movement of "said'movable contact member, acam surface on said manually operable member for moving said movable contact member in said transverse direction, an operating surface on saidmanually operable member for moving said movable contact member in said parallel direction, said transverse stop means being positioned so as to prevent'engagement of :saidoperating surface of said manually operable member with said contact member so long as said imovable contact member is in contact with said transverse stop means and biasing means for moving said movable contact member when released from said transverse .stop means to a positionwhere said operating surface can engage said movable contact member.

7. An electric, circuit breaker comprising a reciprocable manually operable member, a movable. contact member extending, generally transverse to the path of movement of said'manually" operable member, said movable contact member having a contact-carrying portion at one end and a latch'portion at the other end and an intermediate operating portion, biasing means biasing said movable contact member parallel to said path of movement in a circuit-closed direction, latch means for restricting movement of said'latchportion of said movable contact member insaid circuit-closed direction, relatively stationary contactmeans for. limiting the travel of said contactcarrying portion of, said manually movablecontact portiOninsai-d closed-circuit direction, said biasing means operating on said movable. contact member adjacent said intermediate portion, biasing means biasing said movable contact member. transversely to said path of movement of said manually operable member, stop means limiting such transverse movement of said movable contact member whenin engagement with said movable latch member and cam means carried by said manually operable member for camming saidmovable contact member transversely out of engagement with said latch member.

8. An electric circuit breaker comprising a casing, a firstcontact, a second contact movable relative to said first contact between open and closed circuit positions, an M operating. arm for said second contact, said operating arm having a. contact operating portion at one end thereof, a retainingledgenormally stationary with respect to said casingiand adaptedto normally engage the other end of saiddoperating arm, biasing meansbiasingsaid one end of, saidoperating arm toward contact-making position andbiasing saidotherendof said contact arm against said ledge, manually. operable means for sliding said contact operating arm away-from and out of engagement with saidledge while. saidledgeremains stationary, an abutment on said manually operable means, said biasing means rotating. said contact operating arm about said abutment to open-circuit condition upon release of said operating arm from said ledge.

9. An electric circuitbreaker comprisinga first cone operable handle means having a cam surface for slidtact, a second contact movable relative to said first contact between openandcl-osedrcircuit positions, an elongated contact operating member for operating said relatively movable contact, said elongated contact operating member carrying said movable contact at one end thereof and having a latch surface at the other end thereof, latch means carried by saidIinsulating casing for normally engagingand restraining said latch surface of said contact operating member, spring means biasing said movable contact operating member and said movable contact toward said stationary contact and biasing said latch surface,

against said latch retainingmeans, andfmanually operable means engageable with said elongated contact operating;

member and operable to slide said contact member longitudinally away from said' latch retainingsurface toward said rel atively stationary contact, a pivot abutmenton said manually operable member, said biasing means being adapted to rotate said contact operating member about said pivot abutment upon release of said contact member from said latch surface to an open-circuit position.

16. electric circuit. breaker comprising an insulating casing, a first contact, a second contact movable relative to said first contact, an elongated contact member carrying said movablecontact'at one end thereof and having a pivot centrally thereof, a releasable latch surface at the other end of said contact member, latchretaining means, biasing means biasing said contact member into engagement with" saidrelatlvely' stationary" ciprocating fashion along a rectilinear path extendinggenerally transverse to said elongated contact member.- 12. An electric switching device comprising a casing of insulating material, a first contact mounted in said casing, a, second contact movable relativev to said first contact, contact operating meansfor operating said'mov able contact between open andclosed circuit positions;

said contact operating means comprising an elongated contact arm carrying said movable contact adjacent one end thereof and having a latch surface adjacent the other end thereof, said contact arm having an operating portion intermediate its said ends, biasing means urging said contact arm toward said relatively stationary contact and latch retaining means carried by said insulating casing for normally restraining said latch portion of said contact arm, manually operable means for operating said contact member between open and closed circuit positions, said biasing being adapted to rotate said movable contact arm about a portion of said manually operable memberso asto move saidv movable contact away from said relatively stationary contact to an. open circuit position when said latch surface is released from said latch retaining means, and a cam surface on said manually operable member for engaging said oper: ating surface of said contact arm for sliding said contact arm longitudinally out of engagement with said latch retaining surface;

I 13. An electric. circuit breaker comprising a casing of insulating material, a first contact, an elongated contact arm carrying a second contact adjacent one end thereof' and having a latch surface adjacent the other end thereof and an operating portion intermediate the said ends, latch retaining means, biasing means urging said contact arm into engagement with said relativelyvstationary contact and against said latch retaining means, manually ing said movable contact member out ofengagement with said latch retaining means, said biasing means serving to rotate said contact arm about a portion of said manually operable means upon release of said latch from said latch retaining means, said manually operable handle being movable to a position where said cam surface is. out of engagement with said operating portion of said,

contact member, biasing means for moving said contact member upon disengagement of said cam surface 9 from said operating portion to a position wherein it lies in the path of movement of a substantially different portion of said manually operable member.

References Cited in the file of this patent 5 UNITED STATES PATENTS Re. 22,218 Von Hoorn Nov. 3, 1942 2,076,385 Petersen Apr. 6, 1937 2,132,627 Jackson Oct. 11, 1938 10 2,150,012 Von Hoorn Mar. 7, 1939 2,156,762 Jackson et al May 2, 1939 10 Jennings Jan. 21, 1941 Von Hoorn Feb. 25, 1941 Frank et a1. June 1, 1943 Platz May 1, 1945 Jackson Jan. 12, 1954 Cellerini et a1. Nov. 2, 1954 Jackson et al. Dec. 14, 1954 FOREIGN PATENTS Great Britain Dec. 1, 1954

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