US2696540A - Automatic circuit breaker - Google Patents

Description

Dec. 7, 1954 P. M. CHRISTENSEN AUTOMATIC CIRCUIT BREAKER Filed Jan. 27, 1950 INVENTOR. PAUL M. CHR/STENSEN BY &L..:

ATTORNEYS United States Patent AUTOMATIC CIRCUIT BREAKER Paul M. Christensen, West 0range,N. Jl,.assignor tollederal Electric Products C0mpany,.Newark,,N;.J;, a corporation ApplicationJanuary'27, 19.50, SerialNo. 140,800

28 Claims. (Cl; 200--11'6)- Thisinvention relates to an automatic circuit breaker, and? more particularly to an improved, combined thermany-responsive, flexiblecontrol member and movable contact memberfor a circuit breaker of the generaltype shown by U. S. Patent No. Re. 23,188.

It is an object of the present invention to'provide a combined movable contact member and flexiblecontrol member of relativelyhigh conductance'carried by a movable switch arm of relatively low conductance so that when said movable contact engages the fixed contact member of the circuit breaker all or substantially all of the current in the circuit will flow 'throughthe contacts and the flexible control-member and little or no current will flow throughthe pivoted switch.- arm' and actuator. Another object isto' provide in-acircuit'breaker, a combined thermally-responsive,flexible controlmember, or bi-metallic strip and movable contact member which is inexpensiveand simple to make, and which maybe inexpensively secured to the switch arm;

Another objct is the'provision of' a switch arm which is of such constructionasto facilitateathe assembly of-' the actuator therewithz A further object istoprovide a combined thermallyresponsive flexible control memberor bi metallic strip and movable contact which is'highly efli'ci'ent and quick acting in interrupting the current flow in acircuit when overload conditions occur.

These and other features, objects-and'advantagesofathe present invention will become apparent from the following description considered inconnection with the accompanying illustrative drawings;

In the drawings:

Fig. 1 isa side elevation view of'acircuit breaker embodying the present invention;

Fig;.2 is an end view thereof as seen-from-l'ine2 2 of Fig. 1;

gig. 3 is a view. similar to Fig. 2 showing'the other en Fig. 4 is a sideelevation viewofthe-present invention with the cover of the casing removed and the circuit breaker mechanism in open position;-

Fig; 5'-is a view similar'to-Fig: 4 with'the'circuit breaker mechanism in: closed position;

Fig. 6-is a'sectional view along-66- of Fig. 5;

Fig. 7is an enlarged'fragmentary sectional'viewalong line 77 of Fig. 5; and

Fig. 8 is a sectional view along-line 88 of'Fig. 5.

Referring now to thedrawings, the presentinvention is-illustrated as embodiedin a'circuit'breali'er' of'the gencral. type shown in Patent No. 23,188 to Humpage, and in the pending" application of ThomasM'. Cole, Serial No. 127,433, filed Nov. 15, 1949', now Patent-2,647, 186, issued July 28, 1953, and assigned to the assignee of this application. The circuitbreakeris-indicated general by the numeral It). As illustrated in'Fig. 2' the circuit breaker comprises a two part insulated casingor housing; One part 12' is formed with' a recess containing; the circuit breaker mechanism, while the other part 14constitutes a cover. Each of said parts is formed of' insulationpreferably by a molding operation. The parts of the casing or housing interfit and are secured together in housing defining relation in any suitable way, for example, by bolts 16'. Casing part 12 has an'open recessed portion 18 which forms an arcing chamber so-that' are formed gases may escape to the exterior of the housing through vent..20'. The'front of casing part1 12Iissprovided with a recessed. portion which: defines an opening 22: through which handle 24 projects for manual operation of the circuit breaker mechanism. Stops 26 and28 of the casing part 12 limit the pivotal movement of handle 24 in opposite directions. The cover part 14' is provided on its inner surface with a thickened portion 30 having a form complementary to portion 36 of casing part 12. When the casing and cover parts are in'housing defining relation, the ends 32 and 34of thickened portion 30 abut the shoulder 38 and the step 40, respectively, (Fig. 5). Thickened portion 30 together with portion 36 are positioned in spaced confronting relation forming a slotted bounding wall of the arcing chamber 18-. Terminal member 42 is positioned in open recess portion 44 of casing part 12. Conductor 46 is preferably integral with terminal member 42 and extends into open recessed portion 18 and at its free end carriesstationary contact 48. It will be noted that terminal member 42 cannot be removed from casing part 12 when the cover is secured thereto since-movement in one direction in-a horizontal plane is prevented by stop 50, and movement in a vertical plane is prevented by the conductor 46-positioned in recess 52, and'underlying projection 56 andthe overlying projection 58 which abuts conductor 46. The'other terminal member is here shown as a plug-in terminal prong or stab contact 54 and is preferably, but not necessarily, of the general type illustrated and described in application, Serial No. 127,432, filed by Thomas M. Cole andme Nov. 15, 1949 as joint inventors now Patent No. 2,647,225, dated'luly 28, 1953, and assigned to the assignee of my present invention, and in said application, No. 127,433, filed by Thomas M. Cole Nov. 15, 1949, now Patent No. 2,647,186 and assigned to the assignee of my present invention. As described in said applications, the casing is provided at one end thereof, with a rc-entrant lower portion 60 formed in both casing part 12'and cover part 14, and a chamber 62. Said plug-in terminal prong or stab contact 54 is mounted vertically in said chamber, said stab contact being preferably adapted for making contact with a terminal block unit of a terminal plate assembly (not shown), and being provided with laterally extending portions or arms 64 which are removably positioned in cooperating recesses 66 formed'in the walls of said chamber, as illustrated and described in said applications. As further described in the above identified applications, the casing is provided, at one end thereof, with'an open recess 68 in part 1 2 and preferably adapted to engage a hooked element of the terminal plate'assembly. Flexible conductor 70 is secured at one endto terminal member 54, and at'the' other end to thermal member 86. It will be understood that the present invention is not limited to circuit breakers of the plug-in type and that in lieu of prong contact terminal 54, the circuit breaker 10 may be provided with any other type of terminal;

Referring now to the circuit breaker mechanism in particular, the handle 24 is preferably formed with a pair of aligned opposed pivot pins 72 projecting from both sides of the handle, said pins being received in aligned bearing recesses 74 formed in companion casing parts 12 and 14, respectively, for pivotal movement therein.

A substantially U-shaped switch arm member 76 is preferably made in one piece having legs 78 and offset flanges 80 (Fig. 7). Switch arm member 76 is mounted by pivot 'pin 82 in casing parts 12 and 14-forpivotal movement therein, the opposite ends of'pivot'pin 82 being received in aligned bearing recesses 84 in said casing parts 12' and 14, respectively. Said U-shaped member 76 is preferably, butwithout limitation, formed of a metal of low conductivity such as for example, Nichrome. A thermal, current responsive member 86 which is preferably a thermostatic, bi-rnetallic flexible strip, is prov-ided'with a movable contact 88, on the end opposite the free end 90 thereof, for engagement with and disengagement from stationary contact 48. Bi-metallic strip 86 is-preferably made of metal of a relatively high conductivity in comparison with that of switch arm 76. Strip 86 is of such size and'shape as to fit snugly within the recesses formed by the interior surfaces of offset flanges 80 (substantially intermediate of' the ends) of switch arm 76 (Figs. 4, 5 and 7). Although the bi-metallic strip may be secured by rivets or otherwise to the switch arm member 76, it is within the scope of this invention to press-fitthe bi-metah lic strip within the said recesses of the U-shaped switch arm without any connection therebetween. It will be noted from Fig. 7 that the transversely extending portion of the switch arm 76, between the flanges 8t180, provides a rigid backing for the strip 86 adjacent the end portion 102 thereof which is provided with the movable contact 88. Since said end 102 extends only slightly from said backing, it will be apparent that contact 88 is mounted substantially rigidly and is non-yieldable when it engages its companion stationary contact 48 which is also rigidly mounted so as to be non-yieldable upon said engagement. The free end 90 of the bi-metallic strip 86 is positioned to releasably engage a latch member 92 at one end of one arm of an actuator or lever 94, said actuator being preferably of solid or one piece construction mounted on pivots 95 within legs 78 of the U-shaped switch arm 76.

Heretofore, since the movable contact was carried by the integral pivoted switch arm, both being of relatively highly conductive material, the switch arm 76 and the actuator 94 formed a shunt path for the circuit current along with the free end 90 of the bi-metallic strip and flexible conductor 70. As a result, only a part of the circuit current flowed through the desired path of the bimetallic strip and the flexible conductor. The present construction, however, allows little or no current flow through the shunt path described above since the switch arm is formed of material which is a relatively poor conductor, while the integral, bi-metallic strip and movable contact is formed of material which is a relatively good conductor. As little or no current flows in the switch arm 76 and in the actuator 94, arcing between strip 86 and actuator 94 which might otherwise occur upon tripping of the breaker under load is eliminated. Also, although it is within the scope of this invention to insulate actuator 94 from switch arm 76, this is unnecessary in view of the small, if any, flow of current in said switch arm.

Handle 24 is operatively connected to actuator 94 by a resilient link 96, and one end of link 96 passes with slight clearance through an opening 98 in the actuator 94, while the other end passes with slight clearance through an opening 100 in the adjacent end of handle 24.

The mechanism constituted by handle 24, switch arm 76, movable contact member 88, thermal strip 86, actuator 94, and link 96 is similar to and operates substantially in the same way as corresponding mechanism in the above identified United States Patent No. Re. 23,188. As previously indicated, the stationary contact 48 is rigidly or fixedly secured in position so that no appreciable movement thereof is possible, and the movable contact 88 is carried by the end portion 102 of strip 86, which end portion is secured to and rigidly carried by the movable arm 76 so that, substantially, it cannot move relatively thereto. The necessary resiliency in or in association with the circuit breaker mechanism for moving and holding the switch arm 76 is provided by the resilient link 96 which, as here shown, is of loop form to provide said resiliency. The resiliency of link 96 permits it to yield as the toggle, constituted by said link and the handle 24, approaches its overset relationship, as the handle is moved from the open-circuit position thereof illustrated in Fig. 4 to the closed-circuit position thereof illustrated in Fig. 5. During said movement of the handle, the contacts are brought into engagement just before the toggle reaches its dead center position. Continued pressure on the handle serves to compress the link 96 until the dead center position is reached, the link serving to apply the required contact pressure. When the handle is moved beyond the dead center position to the closed-circuit position, the force resiliently applied by the link 96 serves to maintain the contact pressure between the contacts 48 and 88, since the latter is rigidly mounted relative to the switch arm 76, and also to hold the toggle in the overset position. End portion 102 of movable contact member 86 abuts step 40 of casing part 12 in disengaged condition of the companion contacts, said step 40 serving to limit the movement of the movable contact member in its circuit opening position.

A compression, coil spring 104 placed between the switch arm member 76 and companion handle 24 operates to bias the movable contact member and the handle to its open circuit position. One end of the coil spring engages a lug 106 on handle 24, and the other end of said spring engages a lug 108 integral with the companion switch arm member 76.

The thermal, currentresponsive member 86 is operable not only in response to the heating effect of the current passing through it, but there is preferably additional means for operating said member independently of the response of said strip itself to the current, said means operating in substantially the same way as the electromagnetic means in said above identified Patent No. Re. 23,188. Said additional means comprises an electro-magnetic member 110 mounted on thermal member 86 near the free end 90 there of, and a companion rigid armature 112 integral with the switch arm member depending therefrom, and disposed in spaced, confronting relation to the electro-magnetic member. It will be understood that when excess current flows through thermal, currentresponsive member 86, the magnetic attraction between members 110 and 112 results in the deflection of himetallic, thermal strip 86 for disengaging the latter from the companion arm of the actuator, and in this connection it will be understood that since member 112 is rigid and member 110 is flexible, member 110 is movable by magnetic attraction toward member 112, thus deflecting or unlatching the thermal member from the companion actuator.

Also, as here shown, the switch arm member 76 is provided with a generally circular, tapered aperture 114 and a tapered pin 116 for calibrating the circuit breaker. It will be understood that as pin 116 is forced into aperture 114 the portion of the switch arm member at the right of pin 116 (Figs. 4 and 5) is bent upwardly in its own plane to decrease the amount of overlap of the latching member 92 of actuator 94 at the edge of the free end 90 of the thermal strip 86 so that less deflection of said strip is required to trip the breaker. It is, however, to be understood that a calibrating screw may be used in place of said tapered pin to perform the function stated above.

While I have shown and described the preferred embodiment of my invention, it will be understood that certain changes in the details of construction and in the arrangement of the parts may be made without departing from the underlying idea or principles of the invention within the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. In an automatic circuit breaker, a stationary contact, a movable member having a flexible circuit-controlling part provided with a substantially rigid portion movable thereby into engagement with and disengagement from said stationary contact, manually operable actuating means, the remainder of said part being movable relatively to said movable member for latching the latter to and unlatching it from said actuating means, said remainder flexing in response to predetermined current in the circuit whereby to unlatch said movable member, means operable upon the unlatching of said movable member to move the latter whereby to disengage said part from said stationary contact, and means operable upon said movable member when said portion is in engagement with said contact for resiliently biasing said portion toward said contact, whereby to provide resilient contact pressure between said contact and said portion in the closed condition of the circuit breaker.

2. In an automatic circuit breaker, a stationary contact, a movable member having a flexible circuit-controlling part provided with a substantially rigid portion movable' thereby into engagement with and disengagement from said stationary contact, manually operable actuating means, the remainder of said part being movable relatively to said movable member for latching the latter to and unlatching it from said actuating means, said remainder flexing in response to predetermined current in the circuit whereby to unlatch said movable member, means operable upon the unlatching of said movable member to move the latter whereby to disengage said part from said stationary contact, and means operable upon said movable member when said portion is in engagement with said contact for resiliently biasing said portion toward said contact, whereby to provide resilient contact pressure between said contact and said portion in the closed condition of the circuit breaker, said movable member having a relatively high resistance to current flow and said part having a relatively low resistance to current flow whereby substantially none of the current will flow through said movable member and said actuating means, thereby substantially reducing arcing at said actuating means upon the unlatching of said movable member.

aeomeao 3'. In an: automatic: circuit breaker, a-stationary contact; azmovablemember of -relatively low currentzconductivity, provided: with a: curre: ;-responsive. contact element of relatively high. current: conductivity said element having a: nonrflexible. portionmovable-by said-member into engagement withand disengagement from said stationary contact;.manually operable; actuating means, said element having aflexible portion movable relatively to said movablemember: for latching the latter'to and unlatching it from said. actuating means, said latter portion flexing in responseito' predetermined current'in thecircuit whereby to: unlatch said movable member, means operable upon the unlatching of said movable member to move the latter whereby todisengage. said-elementfrom said stationary contact, and means operable upon saidv movable memher when said nonsflexible portion is in engagement with said; stationary contact for resiliently biasing said nonflexible portion toward saidstationary contact, whereby totprovide resilient contact pressure between said stationary contact and saidv element in the closed condition of thecircuit-breaker.

4; In an automatic circuit breaker, a;stationary contact, an movable member having a current responsive strip bodily movable therewith toand from said stationary contact, said strip having a portion provided with a movable contact'engageable with and disengageable from said stationary: contact, manually operable actuating means, said strip/being movable relatively to said movable member for latching the latter to and-unlatching it from said actuating means, said strip flexing in response to predetermined current in the circuit whereby to unlatch said movable member, means operable upon the unlatchingof said movable member to move-the latter whereby to disengage saidmovable contact from said stationary contact, and means operable upon said movable member whensaid contacts are engaged for resiliently biasing said movable contact toward said stationary contact, whereby to provide resilient contact pressure between said contacts in theclosed condition of therbreaker.

5. In an automatic circuit breaker, a stationary contact, a member movable toward and away from said contact, a current responsive element rigidly supported inter mediate the'endsthereofby and bodily movable with said member, said element having arnovable contact adjacent its area: of? support engageable with and disengageable fromsaid stationary contact, manually operable actuating means-including alatch member pivotally carried by said movable'member, said element being movable relative to said movable member for engaging and disengaging a part thereof spaced from said area withand fronrsaid latch ableupon the unlatching of said movablemember to 5 move the latter away from said-stationary contact whereby to disengage the movable contact therefrom, and means operable" upon said movable member when: saidcontacts are engaged for: resiliently biasing said movable. contact toward said stationary contact, whereby toprovide resilientrcontact pressurebetween said contacts in' the closed conditionof the breaker.

6. In anautomatic circuit breaker, a stationary contact,',a member movable toward and away from said contact, a current responsiveelement rigidly carried adjacent one end thereof-by and bodily movable with said member, said element having a movable contact at said one end thereof engageablewitlrand disengageable from said-stationary contact, manually operable actuating'means including alatch member pivotally carried by said movable member, said element being movable relative to said movable member for engaging and disengaging the other end of said element and said latch member for latching saidmovable member to and unlatching it from said actuating means, said element moving in response topredetermined'current in the circuit whereby to unlatch said movable member, and means operable-upon the unlatching of said movable member to move the latter away from said stationary contact whereby to disengage the movable contact therefrom, and means operable upon said movable member when said contacts are engaged for resiliently biasing said movable contact toward said stationary contact,.whereby to provide resilient contact pressure between saidcontacts in the closed condition of the breaker;

7. Inan. automatic circuit breaker, a stationary contact, atmovable member having a current-responsivepart movable, thereby intoengagement with and, disengagement from; said stationary contact, manually operable actuating means, said part being movable relatively to said movable member for latching the latter to and unlatching it from said actuating means, said part flexing in response to predetermined current in the circuit whereby to unlatch said movable member, and means operable upon the unlatching of said movable member to move the latter whereby to disengage said part from said stationary contact, said movable member having a portion which constitutes a rigid support on which said flexible part is carried, said part having a contact portion at said rigidsupport for engagement with said stationary contact and aflexible latching portion extending from said rigid support and engageable with said actuating means, and means operable upon said movable member when said contact portion is in engagement with said stationary contact, whereby to provide resilient contact pressure between said contact portion and said stationary contact in-the-closed condition of the circuit breaker.

8. In an automatic circuit breaker, a stationary contact, a movable member having a current-responsive part movable thereby into engagement with and disengagement from said stationary contact, manually operable actuating means, said part being movable relatively to said movable member'for latching the latter to and unlatching it from said actuating means, said part flexing in response to predetermined current in the circuit whereby to unlatch said movable contact member, and means operable upon the unlatching of said movable member to move the latter whereby to disengage said part from said stationary contact, said movable member having spaced opposing portions provided with an interconnecting portion on which said flexible part is mounted in face-to-face disposition, said part having a contact portion which is substantially rigid relative to said interconnecting portion for engagement with said stationary contact and a latching portion extending, from said interconnecting portion and engageable with said actuating means, said actuating means including a member pivotally mounted between said spaced opposing portions of the movable member and in latching engagement with said latching portion of said flexible part, and means operable upon said actuating means when said contact portion is in engagement with said stationary contact, whereby to provide resilient contact pressure between said contact portion and said stationary contact in the closed condition of the circuit breaker.

9, In a circuit breaker of the type having a rigidly mounted stationary contact and actuating means operable to make and break a circuit at saidstationary contact, the combination withsaidstationary contact of a movable member having a thermally-responsive part provided with a rigidly mounted portion movable thereby into engagement with and disengagement from said stationary contact'for respectively making and breaking said circuit, said part having-a flexible portion movable relatively to said movable member for latching the latter to and unlatching it from said actuating means, said latter portion flexing in response to predetermined current'in the circuit whereby to unlatch said movablemember, means operable upon the unlatching of said movable member to move the latter whereby to disengage said part from said stationary contact, and means operable upon said movable membar when said rigid portion is in engagement with said stationary contact for resili ntly biasing said rigid portion toward said Contact, whereby to provide resilient contact pressure between said rigidly mounted portion and said contact'when the breaker is closed.

10. In a circuit breaker of the type having a stationary contact and actuating means operable to make and break a circuit at said stationary contact, the combination with said stationary contact of a movable member having a thermally-responsive part movable thereby into engage- .ient with and disengagement from said stationary contact for respectively making and breaking said circuit, said part being movable relatively to said movable member for latching the latter to and unlatching it from said actuating means, said part flexing in response to predetermined current in the circuit whereby to unlatch said movable member, and means operable upon the unlatching of said movable member to move the latter whereby to disengage said part from said stationary contact, said movable memher and said-actuating means being formed, of a metal having a relatively low current conductivity and providing a first current path through said breaker, and said flexible part having a relatively high current conductivity and forming a second current path through said breaker whereby substantially all of the current will flow through said flexible part when it engages said stationary contact.

11. In a circuit breaker of the type having a rigidly mounted stationary contact, actuating means operable to make and break a circuit at said stationary contact and a thermally-responsive bi-metallic strip in latched engagement with said actuating means in the circuit-making condition of said circuit breaker, said strip disengaging said actuating means in response to predetermined current in the circuit for breaking said circuit; the combination with said stationary contact of a movable contact member mounted for movement toward and away from said stationary contact, said strip being carried by said member and being provided with a portion which is rigidly mounted relative to said member for engagement with and disengagement from said stationary contact upon the movement of said movable member toward and away from said stationary contact, said strip being movable relatively to said movable member for latching the latter to and unlatching it from said actuating means, means operable upon the unlatching of said movable member to move the latter whereby to disengage said movable contact from said stationary contact, and means operable upon said movable member when said portion is in engagement with said contact for resiliently biasing said portion toward said contact, whereby to provide resilient contact pressure between said contact and said portion in the closed condition of the circuit breaker.

12. In a circuit breaker having a rigidly mounted stationary contact, a manually operable member provided with resilient link means, means operatively connected between said link means and said stationary contact for making and breaking a circuit at the latter and for providing shunt current paths through said circuit breaker, said operatively connected means comprising a member of substantially low current conductivity mounted for pivotal movement, a thermally-responsive bi-metallic element of substantially high current conductivity secured thereto for bodily movement therewith and relatively movable thereto, one end of said element being rigidly mounted relative to said member and being engageable and disengageable with said stationary contact, a latch member mounted for pivotal movement on said low current member, said latch member being connected to said resilient link means and being in latched engagement with the other end of said bi-metallic element in the engaged condition of the latter and said stationary contact for establishing a maximum current path through said bimetallic element and a minimum current path through said low current member and said latch member, said bi-metallic element unlatching from said latch member in response to predetermined current in the circuit, and means operable upon said unlatching to move said low current member whereby to disengage said bimetallic element from said stationary contact, said resilient link means being operable in said engaged condition to resiliently bias said one end against said stationary contact.

13. A movable contact mechanism for a circuit breaker having a stationary contact, said mechanism comprising a movable U-shaped member biased for pivotal movement away from said contact, a thermostatic element mounted in face-to-face disposition on the base of said U and having a portion extending in rigid relationship therefrom and adapted to engage said stationary contact against said bias, and a latch member mounted for pivotal movement between the arms of said U at a point spaced from said thermostatic element, the latter being movable relative to said movable member and having a portion spaced from said first mentioned portion in latched engagement with said latch member when said first mentioned portion thereof is engaged with said stationary contact, the latched portion unlatching from said latch member in response to predetermined current conditions in the circuit whereupon said movable member is moved by the bias thereon to disengage said thermostatic element and said stationary contact, and resilient means operable upon said latch member when said first mentioned portion is engaged with said stationary contact to resiliently bias said first mentioned portion against said stationary contact.

14. In an automatic circuit breaker provided with relatively movable contacts, a flexible circuit-controlling member provided with one of said contacts, a carrier member for said flexible member having opposed recessed portions in which said flexible member is secured and a part for mounting said carrier for movement for engaging and disengaging said relatively movable contacts, and means for actuating said carrier member including a part movably mounted thereon and releasably engaged by said flexible circuit-controlling member, and resilient means operable upon said carrier member when said contacts are engaged for resiliently biasing said one contact toward said other contact whereby to provide resilient contact pressure between said contacts.

15. In a circuit breaker, a stationary contact and a companion movable contact engageable with and disengageable from said stationary contact, a movable switch member, a current responsive latch provided on said movable member, said latch having a portion free to flex relative to said movable member and a portion rigidly mounted relative thereto, said latter portion being provided with said movable contact, an actuator mounted on said movable member and operatively connected thereto, under the control of said latch, for closing the circuit breaker, a manually operable handle, and a connection operative between said handle and said actuator, whereby said handle is effective to operate said actuator, said connection being resilient and being operable When said actuator is latched to said movable member and said contacts are in engagement for resiliently biasing the movable contact toward said stationary contact, whereby to provide resilient contact pressure between said contacts in the closed condition of the circuit breaker.

16. A circuit breaker, as defined in claim 15, further characterized in that said resilient connection is constituted by a resilient link connected between the handle and the actuator.

17. In a circuit breaker, a stationary contact provided on a substantially rigid support and a companion movable contact engageable with and disengageable from said stationary contact, a movable switch member, a current responsive latch provided on said movable member, said latch having a portion free to flex relative to said movable member and a portion rigidly mounted relative thereto, said latter portion providing a substantially rigid support for said movable contact, an actuator mounted on said movable member and operatively connected thereto, under the control of said latch, for closing the circuit breaker, a manually operable handle, and a connection operative between said handle and said actuator, whereby said handle is effective to operate said actuator, said connection being resilient and being operable when said actuator is latched to said movable member and said contacts are in engagement for resiliently biasing the movable contact toward said stationary contact, whereby to provide resilient contact pressure between said rigidly mounted contacts in the closed condition of the circuit breaker.

18. A movable contact mechanism for a circuit breaker, said mechanism comprising a member mounted for pivotal movement and having opposed arms and an interconnecting portion, a flexible thermostatic strip secured in face-to-face disposition on said interconnecting portion, said strip having a contact making portion and a latching portion, said latching portion being flexible in the plane of said pivotal movement in response to predetermined current flow through the circuit breaker, said arms extending laterally of said connecting portion at one side thereof in the direction of said latching portion, and a lever mounted for pivotal movement between said arms laterally of said connecting portion for latching engagement by said latching portion.

19. A movable contact mechanism for a circuit breaker, said mechanism comprising an integral movable switch member mounted for pivotal movement, a flexible thermostatic control element carried by said member for bodily movement therewith, an actuator pivotally mounted on said member and engageable with one end of said control element in the closed condition of the circuit breaker, said control element being flexible in a direction transversely of its opposite sides and being provided with a contact on one of said sides adjacent the other end thereof.

20. A movable contact mechanism for a circuit breaker, said mechanism comprising an integral movable switch member mounted for pivotal movement, a

flexible thermostatic control element carried by said member for bodily movement therewith, an actuator pivotally mounted on said member and engageable with one end of said control element in the closed condition of the circuit breaker, said control element being flexible in a direction transversely of its opposite sides and being provided with a contact on one of said sides adjacent the other end thereof, said integral member being U-shaped and one of said sides being in surface-to-surface abutment with the base of said U.

21. In an automatic circuit breaker provided with relatively movable contacts, a flexible thermostatic circuitcontrolling member provided with one of said contacts, an integral carrier member for said flexible member, said carrier member having a part on which said control member is mounted for movement for engaging and disengaging said relatively movable contacts, means for actuating said carrier member including a part movably mounted thereon and releasably engaged by said flexible circuit-controlling member, and electro-magnetic means operable in response to the current carried by said control member to flex the latter for eflecting relative movement of said contacts.

22. In an automatic circuit breaker provided with relatively movable contacts, a flexible thermostatic circuitcontrolling member provided with one of said contacts, an integral carrier member for said flexible member, said carrier member having a part on which said control member is mounted for movement for engaging and disengaging said relatively movable contacts, means for actuating said carrier member including a part movably mounted thereon and releasably engaged by said flexible circuit-controlling member, and electro-magnetic means operable in response to the current carried by said control member to flex the latter for eifecting relative movement of said contacts, said electro-magnetic means comprising a rigid armature provided on said carrier.

23. In an automatic circuit breaker provided with relatively movable contacts, a flexible thermostatic circuitcontrolling member provided with one of said contacts, an integral carrier member for said flexible member, said carrier member having a part on which said control member is mounted for movement for engaging and disengaging said relatively movable contacts, means for actuating said carrier member including a part movably mounted thereon and releasably engaged by said flexible circuit-controlling member, and electro-magnetic means operable in response to the current carried by said control member to flex the latter for effecting relative movement of said contacts, said electro-magnetic means comprising an electro-magnetic member provided on said control member and a rigid armature provided on said carrier.

24. An automatic circuit breaker, as defined in claim 20, further characterized in the provision of a rigid electro-magnetic armature integral with the base of said U for flexing said control element in response to predetermined current flow therethrough.

25. An automatic circuit breaker, as defined in claim 10, further characterized that a movable contact for engagement with said stationary contact is provided on a a portion of said thermally responsive part and said portion is rigidly mounted by said movable member.

26. In a circuit breaker, complementary casing parts formed of insulation material and defining a housing provided with laterally spaced walls having aligned bearings, a movable contact mechanism for said circuit breaker disposed between said walls, said mechanism all) comprising an integral switch member having opposed arms and an interconnecting portion, means supported by said bearings for mounting said arms on the adjacent walls, respectively, for pivotal movement relative thereto, said interconnecting portion extending between said walls, and a flexible thermostatic strip secured in face-toface disposition on said interconnecting portion, said strip having a contact making portion and a latching portion, said latching portion being flexible in the plane of said pivotal movement in response to predetermined current flow through the circuit breaker.

27. In a circuit breaker, a housing provided with laterally spaced walls, a movable contact mechanism for said circuit breaker disposed between said walls, said mechanism comprising an integral switch member having opposed arms and an interconnecting portion, means mounting said arms on the adjacent walls, respectively, for piovtal movement relative thereto, said interconnecting portion extending between said walls, and a flexible thermostatic strip secured in face-to-face disposition on said interconnecting portion, said strip having a contact making portion and a latching portion, said latching portion being flexible in the plane of said pivotal movement in response to predetermined current flow through the circuit breaker, said walls being provided with aligned bearing apertures, and said mounting means being a pivot member carried by said bearing apertures and exltDending through said opposed arms to mount said mem- 28. In a circuit breaker, a housing provided with laterally spaced walls, a movable contact mechanism for said circuit breaker disposed between said walls, said mechanism comprising an integral switch member having opposed arms and an interconnecting portion, means mounting said arms on the adjacent walls, respectively, for pivotal movement relative thereto, said interconnecting portion extending between said walls, and a flexible thermostatic strip secured in face-to-face disposition on said interconnecting portion, said strip having a contact making portion and a latching portion, said latching portion being flexible in the plane of said pivotal movement in response to predetermined current flow through the circuit breaker, said walls being provided with aligned bearing apertures, and said mounting means being a pivot member carried by said bearing apertures and extending through said opposed arms to mount said member, said bearing apertures being defined in projections provided on the inner surfaces of said walls, respectively, said projections retaining said member against lateral movement.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Re, 23,188 Humpage Jan. 10, 1950 2,035,743 Frank et al Mar. 31, 1936 2,102,545 Rowe Dec. 14, 1937 2,131,640 Sachs Sept. 27, 1938 2,182,864 Frank Dec. 12, 1939 2,203,462 Frank June 4, 1940 2,325,717 Swingle Aug. 3, 1943 2,439,511 Green Apr. 13, 1948 FOREIGN PATENTS Number Country Date 333,008 Great Britain Aug. 7, 1930

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