US3550047A

US3550047A - Circuit breaker with improved trip means

Info

Publication number: US3550047A
Application number: US788229A
Authority: US
Inventors: Francis L Gelzheiser
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1968-12-31
Filing date: 1968-12-31
Publication date: 1970-12-22
Anticipated expiration: 1987-12-22

Description

2 Sheets-Sheet 1 FEG..

. INVENTOR Francis L.Gelzheiser F. L. GELZHEISER CIRCUIT BREAKER WITH IMPROVED TRIP MEANS Dec. 22, 1970 Filed Dec. 31. 1968 6L flW ATTORNEY WITNESSES- Dec. 22,- 1970 l G LZH ISER $550,041

CIRCUIT BREAKER WITH IMPROVED TRIP MEANS Filed Dec. 31. 1968 2 Sheets-Sheet 2 United States Patent 3,550,047 CIRCUIT BREAKER WITH IMPROVED TRIP MEANS Francis L. Gelzheiser, Fairfield, Conn., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Dec. 31, 1968, Ser. No. 788,229 Int. Cl. HOlh 73/48 US. Cl. 335-39 12 Claims ABSTRACT OF THE DISCLOSURE A circuit breaker comprises improved trip means for automatically tripping the breaker open upon the occurrence of certain predetermined overload current conditions. The novel construction, which provides effective low-magnetic tripping action while minimizing the problem of nuisance tripping under shock conditions, is utilized, in one embodiment, in a multi-pole breaker construction to provide an improved multi-pole breaker with dependable positive common trip action.

BACKGROUND OF THE INVENTION In the patent to Gelzheiser et al. No. 2,719,203 there is disclosed a circuit breaker comprising a releasable member releasable to effect opening of the contacts, and an elongated bimetal fixedly supported at one end thereof and having an armature secured thereto in proximity to the free end thereof for latching the releasable member. A stationary magnetic member is supported on the breaker housing opposite the armature. Upon the occurrence of severe overload current conditions the armature, which is attracted to the stationary magnetic member, to unlatch the releasable member during which movement the bimetal is physically flexed. The bimetal thermally flexes upon the occurrence of certain lesser of the load current conditions to move the armature to unlatch the releasable member. In the subject invention, a circuit breaker comprises a releasable member releasable to effect opening of the contacts and an elongated bimetal that is supported at one end thereof on a spring and that supports an armature in proximity to the free end thereof for effecting latching of the releasable member. A stationary magnetic member is supported opposite the armature. Upon the occurrence of severe overload current conditions, the armature is attracted to the stationary magnetic member and the spring support of the bimetal flexes to permit movement of the armature and bimetal to unlatch the releasable member, Upon the occurrence of certain lesser overload current conditions the bimetal thermally flexes to unlatch the releasable member. An advantage of supporting the bimetal on a spring member is that the spring offers less resistance to magnetic tripping movement of the armature than the relatively stiff bimetal. In one embodiment of the invention, two circuit breakers are mounted in abutting side-by-side relationship with a common trip member that is engaged by the releasable member of one of the circuit breakers when the one circuit breaker trips and that is moved to engage and move the bimetal of the adjacent circuit breaker to the tripped position. By providing a spring support of the bimetal, less resistance is offered to magnetic tripping movement of the armature and bimetal in the adjacent circuit breaker thereby providing a more positive common trip action between the circuit breakers. In each of two additional embodiments of the invention, the thermal and magnetic trips are supported by spring means to provide effective low-magnetic tripping action when embodied in a single-pole breaker construction and to provide effective low-magnetic positive common tripping action when embodied in a multi-pole breaker construction.

SUMMARY OF THE INVENTION A circuit breaker comprises a pair of contacts and a latched releasable member movable when released from an initial latched position to a tripped position to effect opening of the contacts. The circuit breaker comprises an elongated bimetal member that is supported, at one end thereof, on a flat leaf spring that is connected to a stationary part of the breaker. An armature, that is mounted on the bimetal member in proximity to the free end of the bimetal member, engages the releasable member to latch the releasable member in the latched position. The spring support biases the bimetal and armature toward the latching position which position is determined by the engagement of the releasable member with the bimetal member. A stationary magnetic member is supported on the breaker housing opposite the armature. Upon the occurrence of an overload above a first predetermined value and below a second predetermined value, the bimetal becomes heated and thermally flexes to rea lease the releasable member with a time delay. Upon the occurrence of an overload above the second predetermined value, the armature is attracted toward the stationary magnetic member and the spring support flexes to permit movement of the bimetal member and armature member to the magnetically tripped position to release the releasable member. In one embodiment of the invention, two of the circuit breakers are mounted in a side-by-side relationship, and a common trip member is mounted between the breakers. Upon the occurrence of a tripping operation in one of the breakers, the released releasable member engages the common trip member to rotate the common trip member to a tripping position during which movement the common trip member engages the bimetal in the adjacent breaker to move the bimetal and armature of the adjacent breaker to the tripped position to effect a tripping operation of the adjacent breaker. In another embodiment of the invention, the bimetal is supported on a supporting spring, with the magnetic member mounted on the bimetal, and an armature is mounted on a spring that is in turn mounted on the bimetal near the free end of the bimetal whereby the magnetic member and armature are both mounted on the bimetal which is supported on the spring support. Common trip action is provided by a common trip member which engages a depending portion of the supporting spring in the adjacent breaker to trip the adjacent breaker when one breaker trips. In another embodiment of the invention, a supporting spring is mounted at one end thereof on a stationary part of the breaker and an armature is mounted on the supporting spring to latch the releasable member. An elongated bimetal is mounted at one end thereof on the supporting spring, and a magnetic member is mounted on the bimetal member whereby the bimetal, magnetic member and armature are all supported on the spring support. Common trip action is provided by a common trip member that is engaged by the releasable member in one breaker and that engages the armature in the adjacent breaker to move the armature of the adjacent breaker to the tripped position.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end view, with parts broken away, of a multi-pole breaker comprising two circuit breakers mounted in a side-by-side relationship with a common trip member interconnecting the breakers to effect a tripping operation in both of the breakers or pole units when there is a tripping overload in one of the breakers or pole units;

FIG. 2 is a sectional view taken generally along the line II-II of FIG. 1 with the breaker being shown in the closed position;

FIG. 3 is a view similar to FIG. 2 with the breaker being shown in the tripped position;

FIG. 4 is a partial view, similar to FIG. 2, illustrating another embodiment of the invention; and

FIG. 5 is a view similar to FIG. 4 illustrating still another embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 of the drawings, there is shown therein a two-pole circuit breaker 3 comprising a circuit breaker 5 and a circuit breaker 7 secured to the breaker 5 in an abutting side-by-side relationship. A common trip member 9 interconnects the breakers for common tripping in a manner to be hereinafter specifically described. The

circuit breakers

5 and 7 are identical. Thus, only the circuit breaker 7 will be specifically described, is being understood that the description applies to both circuit breakers.

The circuit breaker 7 comprises an insulating housing base part 11, that comprises a back portion and four side portions extending toward an open side, and an insulating cover 13 covering the open side of the back portion 11. The housing parts of the two circuit breakers are secured together by rivets 15 (FIG. 2).

Referring to FIG. 2, a circuit breaker mechanism, supported in the housing 11, 13, comprises a stationary contact 21, a movable contact 23, a supporting metal frame 25, an operating mechanism 27 and a trip device 29.

The stationary contact 21 is welded, or otherwise secured, to a plug-in type line terminal structure 31 that is positioned at an opening 33 (FIG. 1) in the housing to resiliently engage a blade or stab in a panelboard or load center when the circuit breaker is mounted in the operating position.

The stationary contact 21 (FIG. 2) cooperates with the movable contact 23 that is welded or otherwise secured to a small flange portion of a flat metallic generally C-shaped contact arm or switch arm 41. Means for operating the contact arm 41 to the open and closed positions comprises an insulating operating member indicated generally at 43 having a V-shaped opening 45 therein, which opening receives a projection 47 of the metallic frame 25. The metallic frame 25 is fixedly supported in the housing 11, 13. The operating member 43 is biased outwardly or upward as seen in FIG. 2, by means to be hereinafter described, to a position wherein the lower edges of the projection 47 engage the lower side walls of the V-shaped opening 45. The contact arm 41 is bent over at its upper end, and a slot is provided at the bent over upper end. Depressions 51 are formed in the bent over upper end on opposite sides of the slot. When the parts are in operating position, a projection molded integral with the operating member 43 extends into the slot of the contact arm 41 to position the operating member 43 relative to the contact arm 41, and pivoting portions 55 on opposite sides of the projection pivotally engage in the depressions 51 of the contact arm 41. The operating member 43 has a handle portion 57 molded integral therewith which extends through an opening 61 in the housing to permit manual operation of the circuit breaker. Arcuate surfaces 63 on opposite sides of the handle portion 57 substantially close the opening 61 in all positions of the operating member 43. Motion is transmitted from the operating member 43 to the contact arm 41 when the breaker is manually operated and from the contact arm 41 to the operating member 43 when the breaker is automatically tripped.

The supporting frame 25 supports an insulating pivot 65. A releasable member 67 is pivotally supported at one end thereof on the pivot 65. The other end 69 of the 4 releasable member 67 is latched by the trip means 29 in a manner to be hereinafter described. Except for the trip means, the operating mechanism 27 is more specifically described in the patent to F. L. Gelzheiser Pat. No. 3,254,176.

As is more specifically described in the above-mentioned Pat. 3,254,176, the ends of the releasable member 67 are olfset and disposed along a plane which is parallel to a plane in which the main body portion of the releasable member 67 is disposed. A spring 71 is connected, under tension, at one end in a slot 73 in the contact arm 41, and at the other end in a slot in a projection 75 that extends from the main body portion of the releasable member 67.

The contact arm 41 is electrically connected to the lower end of a bimetal 77 by means of a flexible conductor 79. The bimetal 77 is part of the trip device 29 that will be hereinafter described. A flexible conductor 81 connects the upper end of the bimetal 77 with a terminal strap 83 that extends through an opening in the end wall of the housing. A terminal connector 85 is connected to the external end of the terminal strap 83 to permit connection of the circuit breaker in a circuit in a manner well known in the art. The closed circuit through the breaker extends from the terminal 31 through the stationary contact 21, movable contact 23, contact arm 41, flexible conductor 79, current-carrying bimetal 77, flexible conductor 81, terminal strap 83, to a conducting line that would be connected to the terminal strap 83 by means of the terminal connector 85. Since the movable contact arm 41 extends downwardly from its pivot, the arc is established adjacent the bottom of the housing in an arc chamber 87 which is connected by a vent passage 89 to an opening in the end of the housing beneath the terminal connector 85.

When the releasable member 67 is in the reset or latched position shown in FIG. 2, the circuit breaker may be manually operated by operation of the operating member 43. Movement of the operating member 43 in a clock wise direction from the on or closed position seen in FIG. 2 to the off or open position carries the upper end of the contact arm 41 to the left of the line of action of the spring 71 whereupon the spring acts to move the concontact arm 41 with a snap action to the open position. The contact arm 41 is stopped in the open position by engagement thereof with a molded projection 90. As can be understood with reference to FIG. 2, the spring 71 biases the contact arm 41 frontward into engagement with the operating member 43 to bias the operating member 43 against the lower edges of the projection 47 about which the operating member 43 pivots. Movement of the operating member 43 in a counterclockwise direction from the off position to the on position moves the upper end of the contact arm 41 to the right of the line of action of the spring 71 to movethe contact arm 41 to the closed position seen in FIG. 2.

The trip device 29 comprises the bimetal 77 which is a flat member that is secured at the upper end thereof to the flat face of a flat leaf spring 91. The upper end of the fiat leaf spring 91 is secured at a fiat face thereof to a flat portion of a projection 93 of the frame 25. The frame 25 is a flat metallic member that is secured in place in the housing between projections of the molded insulating housing, and the projection 93 is bent over to extend in a direction generally normal to the plane of the flat supporting plate 25. The flat spring 91 is fixedly secured to the projection 93 to support the bimetal 77. A rigid armature latch 95 of magnetic material is welded or otherwise fixedly secured to the lower end of the bimetal 77 on the high expansion side of the bimetal 77. The upper end 97 of the armature 95 serves as a latch surface engaging the latch end 96 of the releasable member 67 to latch the releasable member 67 in the latched position seen in FIG. 2. The spring 91 biases the bimetal 77 to the left (FIG. 2), and a stop portion 103 at the latch end 69 of the releasable member 67 engages the bimetal 77 to limit movement of the bimetal to the left end to determine the amount of latch engagement between the releasable member 67 and the armature 97. A flat rigid magnetic member 105 is stationarily supported on the housing nested in insulating projections 107 on the housing part 11 and similar projections on the housing part 13.

The circuit breaker is shown in FIG. 2 in the closed position with the releasable member 67 being latched on the armature 95. Upon the occurrence of a sustained overload current above a first predetermined value, the current-carrying bimetal 77 is heated by the current flowing therethrough, and the bimetal deflects with the lower end thereof moving to the right to move the armature 95 out of latching engagement with the releasable member 67 thereby releasing the releasable member 67. When the releasable member 67 is released, the spring 71 acts to rotate the releasable member 67 in a clockwise direction about the pivot 65 until the releasable member 67 is stopped by engagement thereof with a molded projection 113 of the housing part 11. During this movement, the line of action of the spring 71 moves to the right of the

pivot

55, 51, whereupon the spring 71 biases the contact arm 41 to the open position and moves contact arm 41 so that the line of action of the force exerted by the spring on the operating member 43 moves across the

pivot

45, 47 and actuates the operating member 43 to the tripped position shown in FIG. 3, which tripped position is intermediate the on and oif positions. The operating member 43 is stopped in the intermediate position when a projecton 115 thereon engages the projection 75 of the releasable member 67. Positive separation of the contacts is provided during a tripping operation by the provision of a projection 117 extending from the releasable member 67 which engages the contact arm 41 with a swiping action if the contacts are slow in opening due to sticking or other reasons.

The circuit breaker is trip-free in that the breaker will automatically trip open even if the operating member 43 is held in the closed position.

Before the breaker can be operated following an automatic tripping operation, the releasable member 67 must be reset. This is accomplished by moving the operating member '43- from the tripped position (FIG. 3) clockwise to a position slightly beyond the full off or open 'position. During this movement, the projection 115 on the operating member 43' operates against the projection 75 of the releasable member 67 to move the releasable member 67 counterclockwise to a position wherein the latch surface at the latch end 69 is just above the latch surface 97 of the armature 95 whereupon the spring 91 moves the bimetal 77 (which has cooled and straightened since no current has been flowing therethrough under the tripped condition) to the left until the bimetal 77 engages the stop 103 of the releasable member 67 to thereby relatch the releasable member 67 in the position seen in FIG. 2. Thereafter, the circuit breaker can be manually operated in the same manner as was hereinbefore described.

The circuit breaker is instantaneously tripped upon the occurrence of a. short circuit or severe overload current above a second predetermined value higher than the first predetermined value by operation of the electromagnetic trip of the trip means 29. As can be understood with reference to FIG. 2, the current passing through the bimetal 77 generates magnetic flux which operates through the armature 95, the air gaps between the armature 95 and the stationary magnetic member 105, and through the stationary magnetic member 105. When the current reaches the second predetermined value, this magnetic flux is strong enough to attract the armature 95 toward the stationary magnetic member 105, and the spring 91 flexes to permit movement of the armature 95 toward the stationary magnetic member 105 to the magneticallytripped position seen in FIG. 3 to thereby release the releasable member 67. Upon release of the releasable member 67, the circuit breaker is tripped open in the same manner as was hereinbefore described with regard to the time-delay thermal tripping operation. The circuit breaker is reset and relatched following a magnetic tripping operation in the same manner as was hereinbefore described following the thermal tripping operation.

Referring to FIG. 1, it will be noted that two

circuit breakers

5 and 7 are mounted in a side-by-side relationship to provide a two-pole circuit breaker. Each of the circuit breakers comprises a separate independent circuit-breaker structure. The common trip member 9 is provided in order to provide that both breakers trip when either of the breakers is tripped. The common trip member 9 comprises two insulating

members

121 and 123 tied together for common movement by an insulating connecting member 125. Each of the

members

121, 123 is supported at one end thereof in an opening 129 in the back wall of the associated housing part 11 and at the other end thereof in an opening 131 in the asociated cover 13. The

members

121, 123 are cylindrical at the opposite ends thereof and the

openings

129, 131 are cylindrical to support the

members

121, 123 for pivotal movement about the common axis of the

members

121, 123. Each of the

members

121, 123, is provided with a slot therein, and the flat connecting member 125 is positioned in the slots of the

members

121, 123 to provide for common pivotal movement of the

members

121, 123. Each of the

members

121, 123 is a molded insulating member provided with an actuating part 135 that is molded integral therewith. As can be seen in FIG. 2, each of the actuating parts 135 is positioned at the one end thereof under the associated projection 117 of the asociated releasable member 67 with the other end thereof being positioned opposite the associated bimetal 77. Upon the occurrence of an overload in either of the circuit breakers, the associated releasable member 67 drops to the tripped position seen in FIG. 3 during which movement the projection 117 on the releasable member 67 engages the part 135 of the common trip member 9 to rotate the common trip member 9 in a counterclockwise (FIGS. 2 and 3) direction whereupon the member 135 of the adjacent circuit breaker is moved to engage the associated bimetal 77 to move the associated bimetal 77 and armature to the unlatching postion thereby releasing the releasable member 67 of the adjacent circuit breaker whereup the adjacent circuit breaker is tripped open in the same manner as was hereinbefore described. With each of the bimetals 77 being supported on the associated spring 91, it can be understood that there is less resistance to tripping movement of the bimetal and armature in the adjacent circuit breaker than would be the case if the bimetal 77 were mounted on the projection 93 in which case the relatively stiff bimetal would provide additional resistance to tripping movement of the bimetal and armature in the adjacent breaker. As can be seen in FIG. 1, a common handle tie 139 is connected to two handles 57 to provide for simultaneous operation of the circuit breaker 3. Thus, following a tripping operation of the two-pole circuit breaker the two poles are simultaneously reset by simultaneous movement of the handles 57 to the reset position whereupon the projections 117 of the adjacent breakers will be moved to the position seen in FIG. 2 and the common trip member 9 can then move to an inactive position such as the position seen in FIG. 2. Although it is not necessary for effective operation of the circuit breaker, a suitable spring means could be provided to bias the common trip member 9 to the particular inactive position seen in FIG. 2

Another embodiment of the invention is disclosed in FIG. 4. As can be seen in FIG. 4, a bimetal 77' is supported on a resilient leaf spring 91' that is supported at the upper end thereof to the flat projection 93' of the supporting plate. A generally V-shaped magnetic member is fixedly secured to the bimetal 77 in proximity to the lower or free end of the bimetal with the opposite legs thereof being positioned on opposite sides of the bimetal. An armature latch member 95' is secured to a flat leaf spring 141 that is secured at the lower end thereof to the flat face of the bimetal 77' to thereby support the armature 95' on the bimetal 77'. The releasable member 67 is latched on a latch surface 97' in a window-opening of the armature 95', and a stop surface 143 on the releasable member 67' engages the armature 95' above the window opening to determine the amount of latch engagement between the releasable member 67 and the armature 95'. A molded projection 145 extending from the housing part 11 engages the spring 141 to limit movement to the left of the lower end of the bimetal 77'. The common trip member 9 comprises a depending portion 135 in each of the adjacent circuit breakers with the portion 135 at the left (FIG. 4) thereof being positioned under the associated projection 117 of the associated releasable member 67', and with the associated part 135' being positioned at the right (FIG. 4) thereof adjacent an extension 147 of the associated leaf spring 91'. Other than the above description, the two pole circuit breaker is constructed in the same manner as was hereinbefore described with reference to FIGS. 1-3. Upon the occurrence of a sustained overload above a first predetermined value, the bimetal 77 is heated and flexes with the lower end thereof moving to the right to thereby move the armature 95' to the right to release the releasable member 67 whereupon the releasable member 67' is moved to the tripped position in the same manner as was hereinbefore described with reference to FIGS. 1-3. As the releasable member 67 in the tripped breaker moves to the tripped position, the projection 117 thereon engages the associated part 135 of the common trip member 9' to rotate the common trip member 9' in a counterclockwise (FIG. 4) direction whereupon the part 135' in the adjacent breaker operates against the extension 147 in the adjacent breaker to move the bimetal 77' and armature 95 of the adjacent circuit breaker to the tripped position to thereby trip the adjacent breaker. Following an automatic tripping operation, the two-pole circuit breaker is reset in the same manner as was hereinbefore described during which resetting operation both releasable members 67 are moved to the position shown in FIG. 4 and the springs 91' move the bimetals 77' to the FIG. 4 position with the springs 141 moving the armature 95' to the latching position seen in FIG. 4. The amount of latch engagement between each releasable member 67' and asociated armature 95 is determined by the engagement of the associated stop portion 143 on the associated releasable member 67 with the associated armature 95 above the window opening of the associated armature. Upon the occurrence of a short circuit or severe overload above a second predetermined value, higher than the first predetermined value, in one of the breakers, the magnetic flux generated by the current in the associated bimetal 77 operates in the magnetic member 105 and armature 95 to cause attraction of the associated armature 95' toward the magnetic member 105, and the supporting spring 141 flexes to permit movement of the associated armature 95' to the right toward the associated magnetic member 105 to release the associated releasable member 67'. Upon release of the releasable member 67' in the overloaded pole unit, the two adjacent circuit breakers are operated to the tripped position in the same manner as was hereinbefore described with respect to the thermal tripping operation, and the circuit breakers are reset in the same manner as was hereinbefore described with regard to the thermal tripping operation.

Another embodiment of the invention is disclosed in FIG. 5. In this embodiment of flat elongated leaf spring 91 is fixedly supported at the upper end thereof on the stationary projection 93" of the supporting frame. An

elongated bimetal 77 is supported at the upper end there of on the spring 91", and a generally U-shaped magnetic yoke 105 is secured to the bimetal 77" with the opposite legs thereof being positioned on opposite sides of the bimetal 77". A magnetic armature 95" is fixedly secured to the spring 91" and the releasable member 67 engages a latch surface 97 in a window-opening of the armature 95 with a stop portion 143" of the releasable member 67" engaging the armature 95" at a point above the window-opening. The spring member 91" is bent over at the lower end thereof to extend to the opposite side of the bimetal 77" and an insulating button 151 on the spring member 91 engages the current carrying bimetal 77". The common trip member 9" comprises a separate depending portion 135" in each of the two adjacent breakers with one end of each of the parts 135" being positioned under the associated projection 177" of the associated releasable member 67" and with the other end of the part 135" being positioned opposite the associated armature 95". A molded insulating projection 145" molded integral with the housing part 11" engages the bimetal 77" to limit movement to the left (FIG. 5) of the bimetal 77". Other than the above description, each of the breakers of the two-pole breaker is constructed in the same manner as was hereinbefore described with reference to FIGS. 1-3. Upon the occurrence of a sustained lesser overload above a first predetermined value in either of the adjacent pole units, the associated bimetal 77" is heated and flexes to the right (FIG. 5) whereupon the lower end of the bimetal 77" engages the insulating button 151 to move the spring 91" and armature 95" to the right to release the releasable member 67" to thereby trip the overloaded pole unit. As the releasable member 67" moves to the tripped position, the projection 117" thereon engages the associated part 135" of the common trip member 9" to rotate the common trip member 9" in a counterclockwise (FIG. 5) direction whereupon the part 135 in the adjacent circuit breaker is moved against the associated armature 95" to move the associated armature 95" to thereby release the releasable member 67" of the adjacent circuit breaker to trip the adjacent circuit breaker. Following an automatic tripping operation, the two pole circuit breaker is reset and relatched in the same manner as was hereinbefore described, with each of the spring members 91" moving the associated armature 95" to the latching position seen in FIG. 5 to relatch the associated releasable member 67". Upon the occurrence of a short circuit or severe overload above a second predetermined value higher than the first predetermined value, the magnetic flux generated in the magnetic member and 95", by the current in the current-carrying bimetal 77", operates to attract the associated armature 95" toward the associated magnetic member 105" to effect instantaneous release of the releasable member 67" in the overloaded pole unit to trip the overloaded pole unit whereupon the common trip member 9 is operated in the same manner as above-described to move the armature in the adjacent pole unit to the tripping position to release the releasable member 67" in the adjacent pole unit to thereby effect a tripping operation in the adjacent pole unit.

As can be understood with reference to the drawings, the handle-receiving opening 61 is at the front of the housing with the handle 57 protruding through the opening 61 to enable manual operation. Each of the elongated bimetals (FIGS. 2-5) is supported on the associated supporting spring in proximity to the front end thereof with each of the elongated bimetals extending in the housing generally from front to back in the housing.

Although a two-pole circuit breaker was hereinbefore described, it can be understood that additional pole units could be mounted adjacent the two pole units, and the common trip member 9 could be provided with a similar operating part for each pole unit.

I claim as my invention:

1. A circuit breaker comprising an insulating housing comprising a front having a handle-receiving opening therein and a back opposite said front, a circuit-breaker structure supported in said housing, said circuit-breaker structure comprising a pair of contacts operable to open and close an electric circuit, a handle protruding through said handle-receiving opening and being manually operable to open and close said contacts, a releasable member in an initial position and movable when released to a tripped position to effect automatic opening of said contacts, a magnetic member, a movable magnetic armature in a latching position to effect latching of said releasable member, an elongated current-carrying bimetal, a supporting spring supporting said elongated bimetal and said armature with said elongated bimetal being positioned such that the current in said elongated bimetal generates magnetic flux in said magnetic member and armature, said elongated bimetal extending generally from front to back in said housing and being supported in proximity to the front thereof, upon the occurrence of a sustained lesser overload current above a first predetermined value said elongated bimetal flexing to move said armature to release said releasable member, and upon the occurrence of a more severe overload current above a second predetermined value higher than said first predetermined value said armature being attracted to said magnetic member and flexing said supporting spring to move toward said magnetic member to release said releasable member.

2. A circuit breaker according to claim 1, said supporting spring being a flat leaf spring, said elongated bimetal being secured in proximity to the front end thereof to a fiat face of said leaf spring, and said leaf spring being secured to a stationary part of said circuit breaker.

3. A first circuit breaker according to claim 2, a second circuit breaker according to claim 2, means securing said first and second breakers together in a side-by-side relationship, a common trip member supported on said first and second breakers and comprising a first actuating part in said first breaker and a second actuating part in said second breaker, upon the occurrence of a tripping operation in one of said breakers the released releasable member in the tripped breaker engaging the associated actuating part and moving said common trip member to a tripping position during which movement the actuating part in the adjacent breaker operates to move the armature in the adjacent breaker to release the releasable member in the adjacent circuit breaker.

4. A circuit breaker comprising an insulating housing and a circuit-breaker structure supported in said housing, said circuit-breaker structure comprising a pair of contacts operable to open and close an electric circuit, a releasable member in an initial position and movable when released to a tripped position to effect automatic opening of said contacts, a supporting spring, an elongated current carrying bimetal supported in proximity to one end thereof on said supporting spring, said supporting spring being supported within said housing on a stationary support, a magnetic armature supported on said elongated bimetal in proximity to the free end of said elongated bimetal and on the high expansion side of said elongated bimetal, a relatively stationary magnetic member supported on said housing on the low expansion side of said elongated bimetal spaced from said elongated bimetal, said elongated bimetal said magnetic armature and said relatively stationary magnetic member being positioned such that the current in said elongated bimetal generates magnetic flux in said magnetic armature and said relatively stationary magnetic member, upon the occurrence of a sustained lesser overload current above a first predetermined value said elongated bimetal flexing and moving said magnetic armature therewith to release said releasable member, and upon the occurence of a more severe overload above a second predetermined 10 value said magnetic armature being attracted to said relatively stationary magnetic member and moving toward said relatively stationary magnetic member to release said releasable member during which movement said magnetic armature moves said elongated bimetal therewith while said supporting spring fiexes to permit said movement of said elongated bimetal by said armature.

5. A circuit breaker according to claim 4, said supporting spring comprising a fiat leaf spring, said elongated bimetal being secured in proximity to said one end thereof to said leaf spring, and said leaf spring being secured within said housing to a stationary support to thereby support said elongated bimetal in said housing.

6. A first circuit breaker according to claim 4, a second circuit breaker according to claim 4, means supporting said first and second breakers in a side-by-side relationship, said housings of said first and second breakers having opening means therein, a common trip member supported on said housings and extending through said opening means, said common trip member comprising a separate actuating part in each of said housings, upon the occurrence of a tripping operation in one of said breakers the released releasable member in the tripped breaker engaging the associated actuating part and moving said common trip member to a tripping position during which movement the actuating part in the adjacent breaker is moved to move the elongated bimetal and magnetic armature in the adjacent breaker to thereby release the releasable member of the adjacent breaker which movement of the elongated bimetal and magnetic armature in the adjacent breaker accurs while the supporting spring supporting the elongated bimetal in the adjacent breaker flexes.

7. A circuit breaker comprising an insulating housing and a circuit-breaker structure supported in said housing, said circuit-breaker structure comprising a pair of contacts operable to open and close an electric circuit, a releasable member in an initial position and movable when released to a tripped position to effect automatic opening of said contacts, a supporting spring, an elongated current carrying bimetal supported in proximity to one end thereof on said supporting spring, a magnetic member fixedly secured to said elongated bimetal in proximity to the free end of said elongated bimetal, a magnetic armature, resilient means supporting said magnetic armature on said elongated bimetal in proximity to the free end of said elongated bimetal with said magnetic armature being spaced from said magnetic member, said elongated bimetal said magnetic member and said magnetic armature being positioned such that the current in said elongated bimetal generates magnetic flux in said magnetic member and said magnetic armature, upon the occurrence of a sustained lesser overload current above said first predetermined value said elongated bimetal flexing and moving said resilient support means and said magnetic armature to release said releasable member, and upon the occurrence of a more severe overload current above a second predetermined value higher than said first predetermined value said magnetic armature being attracted to said magnetic member and moving relative to said elongated bimetal toward said magnetic member to release said releasable member.

8. A circuit breaker according to claim 7, said supporting spring being a fiat leaf spring, said elongated bimetal being secured at the one end thereof to said leaf spring, and said leaf spring being supported in said housing on a stationary support.

9. A first circuit breaker according to claim 7, a second circuit breaker according to claim 7, means supporting said first and second breakers in a side-by-side relationship, said housings of said first and second breakers having opening means therein, a common trip member extending through said opening means, said common trip member comprising a separate actuating part in each of said housings, each of said supporting springs comprising an extended part positioned opposite the associated actuating part, and upon the occurrence of a tripping operation in one of said breakers the released releasable member in the tripped breaker operating against the associated actuating part to move said common trip member during which movement the actuating part in the adjacent breaker engages the extended portion of the associated supporting spring to move the associated elongated bimetal and magnetic armature to thereby effect release of the releasable member in the adjacent breaker.

10. A circuit breaker comprising an insulating housing and a circuit-breaker structure supported in said housing, said circuit-breaker structure comprising a pair of contacts operable to open and close an electric circuit, a releasable member in an initial position and movable when released to a tripped position to effect automatic opening of said contacts, a supporting spring, an elongated current carrying bimetal supported in roximity to one end thereof on said supporting spring, a magnetic member secured to said elongated bimetal, said supporting spring comprising an elongated spring member extending the length of said elongated bimetal on one side of said elongated bimetal and comprising a hook-end hooked around to the opposite side of said elongated bimetal, a magnetic armature supported on said elongated spring on said one side of said elongated bimetal and being spaced from said magnetic member, said elongated bimetal said magnetic member and said magnetic armature being positioned such that the current in said elongated bimetal generates magnetic flux in said magnetic member and said magnetic armature, upon the occurrence of a sustained lesser overload current above said first predetermined value said elongated bimetal flexing and operating against said hook-end of said supporting spring to move said supporting spring and magnetic armature to release said releasable member, and upon the occurrence of a more severe overload current above a second predetermined value said magnetic arma- 12 ture being attracted to said magnetic member and said supporting spring flexing as said magnetic armature moves toward said magnetic member to effect release of said releasable member.

11. A circuit breaker according to claim 10, said supporting spring comprising a flat leaf spring supported at one end thereof on a stationary support with the other end thereof comprising said hook-end hooked around to said opposite side of said elongated bimetal, and stop means limiting movement of said elongated bimetal and magnetic member toward said magnetic armature to thereby provide that said magnetic armature will move to the tripped position upon the occurrence of said severe overload current above said second predetermined value.

12. A first circuit breaker according to claim 10, a second circuit breaker according to claim 10, means supporting said first and second breakers in a side-by-side relationship, said housings of said first and second circuit breakers having opening means therein, a common trip member extending through said opening means and comprising a separate actuating part in each of said housings, upon the occurrence of a tripping operation in one of said breakers the released releasable member in the tripped breaker operating against the associated actuating part to move said common trip member to a tripping position during which movement the actuating part in the adjacent breaker operates to move the magnetic armature in the adjacent breaker to effect release of the releasable member in the adjacent breaker.

References Cited UNITED STATES PATENTS 2,956,133 10/1960 Middendorf 337-54 2,996,589 8/1961 Myers 337-48 HAROLD BROOME, Primary Examiner US. Cl. X.R. 33754