Circuit Breaker

Abstract

An aircraft circuit breaker in which a push-pull manual operator controls a slidable contact carrier. The contact carrier is controlled by a pair of laterally extending slides which are engaged, respectively, with a current-responsive bimetal and an ambient temperature-responsive bimetal. Relative lateral movement of the slides effects disengagement of a latch to permit movement of slidable contact carrier into the contact's open position. A manual latch, operated by the push-pull manual operation, is provided which self-disengages when the automatic latch disengages. The manual latch includes a manual latch member which is mounted independently of the temperature-responsive bimetal and a manual latch surface which is supported on the housing independently of the current-responsive bimetal element which is engageable with the latch member to effect a manual latch for maintaining the contacts in a closed condition.

Description

BACKGROUND OF THE INVENTION

The instant invention is an improvement over the inventions disclosed in U.S. Pat. Nos. 3,287,523 and 3,416,113 which are assigned to the assignee of the instant invention and relates to the invention claimed in the copending application of Preston D. Rowan, Ser. No. 6264, entitled Circuit Breaker, also assigned to the assignee of this invention.

SUMMARY OF THE INVENTION

The invention lies in the provision of a novel thermal latch for a circuit breaker comprising a pair of slides, one of which is controlled by a current-responsive bimetal and the other of which is controlled by an ambient temperature-responsive bimetal. Particularly, an automatic latch member or clevis is provided which engages the latch slide rather than the bimetals so that it does not transmit latching loads to the bimetals.

IN THE DRAWINGS

FIG. 1 is a side elevational view, partially in section, of an improved circuit breaker in accordance with the instant invention with the cover removed therefrom;

FIG. 2 is an exploded view of the manual operator and thermally responsive latch shown in assembly view in FIG. 1;

FIG. 3 is a cross-sectional view taken substantially along the line 3--3 of FIG. 1; and

FIG. 4 is an exploded view of the contacts assembly shown in assembly view in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As best seen in FIG. 1, a circuit breaker 10, in accordance with an exemplary constructed embodiment of the instant invention, comprises an enclosure 12 having a pair of terminals 14 and 16 thereon which extend exteriorly of the enclosure 12 for connection to an electrical source. A threaded ferrule 18 extends exteriorly of the enclosure 12 for the guidance of a manual operator 20. The ferrule 18, in conjunction with a nut (not shown), provides a mounting means for the circuit breaker 10 on a panelboard (not shown).

As best seen in FIG. 2, the manual operator 20 is provided with an end cap 21 and a guide sleeve 22. The manual operator 20 including the end cap 21 and guide sleeve 22 are capable of sliding axial movement with respect to the ferrule 18.

The manual operator 20 is also provided with a central stem portion 24 which is fixed to the manual operator end cap 21. The stem member 24 is provided with a central slot 26 extending upwardly approximately half the length thereof. A central sleeve 30 having a slot 32 corresponding to the slot 26 of the central stem 24 is disposed between the guide sleeve 22 and the central stem 24 for sliding axial motion with respect thereto.

The sleeve member 30 is provided with a clevis or thermally releasable latching member 36 formed as shown in the drawings to provide an abutting latch surface 38 and a hook portion 40. The clevis 36 is pivotally connected to the lower portion of the central sleeve 30 by a pin 41.

As can be seen in FIG. 3, the end portions 39 of pin 41 cooperate with grooves 45 in the housing 12 to guide axial movement thereof.

Referring again to FIG. 2, a first and second manual latching members 42 and 43, respectively are also pivotally connected to the lower portion of the central sleeve 30 by the pin 41. The manual latching member 42 is provided with a latching surface 44 which is adapted to engage a cooperating latching pin 46 which is supported in a fixed position with respect to ferrule 18 by a groove 48.

The manual latching member 42 has a slot 50 including an upper camming surface 52 which is slightly angulated with respect to the axial motion of the central sleeve 30 and a lower camming surface 53 which is severely angulated with respect to the axial motion of the central sleeve 30 to prevent accidental disengagement of the manual latch upon jarring. The central stem 24 is provided with a camming pin 54 extending across the slot 26 therein and through the slot 50 of the manual latching member 42 so as to be in operative engagement with the camming surface 52.

The second manual latching member 43 is positioned parallel to and contiguous with the first manual latching member 42 to engage a second cooperating latching pin 58 in groove 60. The second manual latching member 43 is also pivotally connected to the pin 41 and has an upper camming surface 61 and a lower camming surface 63 operated by the pin 54 in a manner like that of the first latching member 42.

A spring 62 is provided to resiliently bias the guide sleeve 22 upwardly with respect to the ferrule 18. Consequently, the manual operator 20 and the central stem member 24 are resiliently biased upwardly with respect to the ferrule 18.

Referring now to FIG. 4, a movable contact carrier 64 has a central opening 66 therein for acceptance of the clevis 36. The end portions 67 of the contact carrier 64 cooperate with slides 45 in the housing 12 to guide axial movement thereof as shown in FIG. 3.

The contact carrier 64 has a support arm 68 having a pair of movable contacts 70 positioned thereon which is resiliently biased downwardly with respect to the contact carrier 64 by a spring member 71 (FIG. 1). The movable contacts 70 are engageable with fixed contacts 72 to complete a circuit from terminal 14 to terminal 16 through a current responsive bimetal element of the circuit breaker 10 as shown in FIG. 4.

A helical coil spring 74 (FIG. 1) is positioned in a recess 76 of the housing 12 such that it abuts against the housing at one end and the movable contact carrier 64 at its other end so as to normally bias the contact carrier 64 upwardly relative to the housing 12 as seen in FIG. 2.

In accordance with the instant invention, the contact carrier 64 has a laterally extending slot 78 therein for the acceptance of a clevis guide 80 and a latch slide 82. The clevis guide 80 is movable internally of the contact carrier 64 under the influence of an elongated current responsive bimetal 84. More particularly, an end portion 86 of the slide 80 interlocked by a slidable fixture 87 with the current responsive bimetal 84 whereby lateral movement of the slide is controlled by the bimetal. The other end of the clevis guide 80 is provided with a slot 88 which accepts and closely cooperates with the clevis 36 to effect pivoting thereof in response to lateral movement of the slide 80.

The latch slide member 82 abuts the clevis guide 80 and is movable internally of the contact carrier 64 under the influence of an elongated temperature-compensating bimetal 90. The temperature-responsive bimetal 90 is interlocked to an end portion 94 of the latch slide 82 by a slot 92 therein whereby the lateral movement of the slide 82 is controlled by the bimetal. The other end of the latch slide 82 is provided with a slot 96, which, when the circuit breaker is in the contacts closed position, accepts the hooked end 40 of the clevis 36. In the contacts closed position, the latch surface 38 of the clevis 36 abuts the upper surface of the latch slide 82 with a pressure determined by the upward resilient bias provided by springs 71 and 74.

Referring now to FIG. 1, the current-responsive bimetal 84 is fixed to the housing 12 at opposite ends as shown. The temperature-responsive bimetal element 90 is fixed in the housing 12 at its lower end and is mounted for lateral adjustment at its upper end to permit calibration of the circuit breaker 10.

The circuit breaker as shown in the drawings is in the contacts closed condition. In this position, an upwardly acting force is transmitted from the upper surface of latch slide 82 through the clevis 36 to the pin 41. This force causes the latch surfaces of the manual latch members 42 and 43 to bear against the latching pins 46 and 58. As a result, a lateral frictional force is established between the latching surfaces and the latching pins 46 and 58. The lateral frictional force counteracts a laterally inward force provided by the resilient upward bias of the pin 54 against the camming surfaces 52 and 61 so as to prevent a laterally inward motion of the latching members 42 and 43. Upon release of the upward acting force on the latching pins 46 and 58, the camming forces take precedence thereby drawing the latching members 42 and 43 inwardly to remove the latching surfaces from the latching pins 46 and 58, respectively, and permitting upward motion of the manual operator 20. Therefore, it will be appreciated that the manual latch is self-disengaging upon release of the upward force on the clevis member 36.

Upon occurrence of an overload condition, the center portion of the current-responsive bimetal element 84 flexes to the right so as to draw the clevis guide 80 to the right, and consequently, to draw the clevis 36 to the right. Movement of the clevis guide slide 80 to the right pulls the latch surface 38 of the clevis 36 off the latch slide 82 into the opening 96 in the latch slide 82. The force between the latch surface 38 and the upper surface of slide 82 is released permitting upward motion of the contact carrier 64, and consequent disengagement of the contacts 70 and 72, and self-disengagement of the manual latch.

Temperature compensation is achieved through movement of the latch slide 82 with respect to the clevis guide 80 in response to flexing of the center portion of the ambient temperature-responsive bimetal element 90 in accordance with ambient temperature changes. The ambient temperature bimetal element 90 is selected such that increases in ambient temperature causes a movement of the latch slide 82 to the right which is substantially equal to the movement of the clevis guide 80 to the right by virtue of flexing of the current-responsive bimetal 84 in response to ambient temperature changes.

Manual disengagement of the contacts 70 and 72 is accomplished by an upward pull on the manual operator 20 which establishes an additional laterally inward force on the manual latching members 42 and 43 due to the additional force of the stem pin 54 on the camming surfaces 52 and 61. In this regard, it can be seen that the slidable relationship of the central sleeve 30 with respect to the central stem 24 provides "lost" motion therebetween which permits the above-described camming action.

The contacts may be reengaged by depression of the manual operator 20 to move sleeve 30 downwardly to bring the clevis 36 in engagement with the latch slide 82, and consequently, to bring the contact 70 and 72 into engagement whereupon the manual latch members 42 and 43 move laterally outwardly so as to be in position to engage pins 46 and 58, respectively upon release of the manual operation 20 to maintain the contacts 70 and 72 in the closed position.

As can be seen in the drawings, the thermal latch is accomplished at the abutment between the latch surface 88 of the clevis 36 and the upper surface of the latch slide 82. As a result, neither bimetal element 84 or 90 is subjected to latch loads. Moreover, the manual latching member acts on a member directly supported by the housing rather than on either slide. Hence, the bimetal elements 84 and 90 do not act directly against the manual latch.

It is to be understood that the specific construction of the improved circuit breaker herein disclosed and described is presented for the purpose of explanation and illustration and is not intended to indicate limits of the invention, the scope of which is defined by the following claims.

Claims

What is claimed is:

1. An electrical circuit breaker comprising:

a housing;

a pair of external terminals supported by said housing for connection to a source of electrical current;

an internal fixed contact supported by said housing connected to one of said terminals;

a contact carrier biased from said fixed contact having a movable contact thereon which is movable with respect to said housing to a closed position wherein said movable contact is engaged with said internal contact;

an elongated bimetallic element supported by said housing electrically connected to the other of said terminals and to said movable contact when said movable contact is engaged with said fixed contact and responsive to current flow therethrough;

a first slide carried by said contact carrier and extending transversely to said current-responsive bimetallic element, said first slide being controlled by said current-responsive bimetallic element for movement relative to said contact carrier;

an elongated bimetallic element responsive to ambient temperature supported by said housing and disposed substantially parallel to said current-responsive bimetallic element;

a second slide carried by said contact carrier and extending in substantially parallel relationship with said first slide, said second slide being controlled by said ambient temperature-responsive bimetallic element for movement relative to said contact carrier; a manual operator operable by movement with respect to said housing; and

a thermal latch means connected to said manual operator including a thermal latch member and a thermal latch surface associated with one of said first and second slides for maintaining said contacts in said closed position operated by differential movement of said slides caused by a deflection of said current-responsive bimetallic element which is greater by a predetermined amount than the deflection of said ambient temperature-responsive bimetallic element to effect disengagement of said thermal latch member from said thermal latch surface permitting said contact carrier to move said contacts to an open condition.

2. An electrical circuit breaker in accordance with claim 1 wherein movement of said operator means moves said thermal latch member into engagement with said thermal latch surface thereby moving said contact carrier to the contacts closed condition, said manual operator having manual latching means including a manual latch member mounted for movement with said manual operator and a manual latch surface supported by said housing to effect a manual latch for maintaining said contacts in said closed condition when said thermal latch is engaged, said manual latch being self-disengaging when said thermal latch disengages.

3. An electrical circuit breaker in accordance with claim 2 wherein said thermal latch element engages said second slide to apply a force to said manual latch member to maintain said contacts in the closed condition when said predetermined amount of deflection is not exceeded and wherein a predetermined movement of said first slide representative of said predetermined amount of deflection disengages said thermal latching element from said second slide to effect disengagement of said thermal latch means.

4. An electrical circuit breaker in accordance with claim 3 wherein said thermal latch member is pivotally connected to said manual operator for pivotal movement in response to movement of said first slide.

5. An electrical circuit breaker in accordance with claim 4 wherein said first slide includes a slot accepting said thermal latch member for controlling the pivotable movement of said element in accordance with the movement of said first slide.

6. An electrical circuit breaker in accordance with claim 2 wherein said thermal latch member extends from said manual operator to said contact carrier and is controlled by said slides for maintaining the engagement of said manual latch when said thermal latch means is engaged.

7. An electrical circuit breaker in accordance with claim 6 including means supported by said housing for resiliently biasing said contact carrier for movement with respect to said housing to establish a restraining force acting through said thermal latch member which maintains said manual latch member in engagement with said manual latch surface when said thermal latch is engaged and wherein said predetermined movement of said first slide releases said force causing disengagement of said manual latch.