US2663777A - Circuit breaker - Google Patents

Description

I. W. COX

CIRCUIT BREAKER Dec. 22, 1953 2 Sheets-Sheet 1 Filed March 12, 1952 Dec. 22, 1953 w, cox 2,663,777

CIRCUIT BREAKER Filed March 12, 1952 2 Sheets-Sheet 2 Patented Dec. 22, 1953 CIRCUIT BREAKER Irvin WQCox, West Allis, Wis., asslgnor'to. Cutler! Hammer, 1110., Milwaukee, Wis-., a. corporation cf'Delawarc.

Application March 12, 1952, Serial No, 276,168

This invention relates to improvements; in circuit breakers, and more particularly to circuit breakers operated by electro-thermal power elements'.

Circuit breakers of such type are disclosed and claimed in my two applications, Serial Numbers 276,167 and 276,169, for Improvements in Circult Breakers, filed simultaneously herewith. In such circuit breakers there is one spring for performing, the snap action opening and another spring operable in conjunction with cam surfaces to perform the snap action closing.

It is an object of this invention to provide such a circuit. breaker which does not use two such springs and is therefore less costly to make and relatively more. easily assembled.

Another object of this invention is to provide a circuit breaker including an electro-thermal power element having a combined wiring terminal and support of novel and inexpensive form.

The first of these objects is obtained by using a. single spring which has a. part placed under compression for use in snap breaking of the circuit and another part placed under tension transiently during manual closing of the circuit with a snap action. This spring is connected to one ieg of a kick-out member so that said first mentioned part thereof when released will expand to move the kick-out member and the contact-carrying power element with a snap action to circuit open position. Intermediate its ends such spring has a keeper which in the uncxpanded condition of the power element is in alignment with a camlatch on the control lever. This cam-latch also coacts with the kick-out member so that during operation of the cam-latch from Reset to On the compression part of the spring below the keeper is compressed and the tension part of the spring above the keeper is stretched until a notch on the cam-latch comes into alinement with a camfollower on the kick-out member. When this oc curs the tension part Will cause the kick-out member to snap down to circuit-closed position. To manually open the circuit breaker the control lever is moved to Off position and the camlatch moves out from above the keeper to snap open the circut. When the circuit breaker is in closed position overload conditions will cause the keeper to disengage from the cam-latch and the compression part of the spring forces the kick-out member and the movable contact to open circuit position.

The second of these objects is obtained by fold ing a strip of brass or copper so that an arm on one-half of one end is in edge-facing relation with an am; on the opposite half of the other end to form a central slot into which the end of the power element is fitted and secured, preferably by welding.

The novel features which are considered charcteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof. will best be understood from the following description ofa specific embodiment. when read in connection with the accompanying drawings in which;

Figure 1 is an enlarged view in front-side elevation of a circuit breaker embodying the present invention, the cover of the housing being omitted for the sake of clarity in illustration;

Fig. 2 is a, sectional view, taken on line 2-.-2 of 1, showing the power element collapsed, the circuit breaker contacts being in closed position, as shown in Fig. 1;

Fig. is a sectional view similar to the view of Fig. 2,, but with the power element expanded and the contacts open, as. shown in dotted lines in Fig. 1;

Fig. 4 is a top plan view of the power element and its mounting terminal;

Fig. 5 is a view, partly in side elevation and partly in section, of the control lever and latching cam, cam-follower, and keeper forming parts of the latching mechanism and manual control and reset;

Fig. 6 is a sectional view, taken on line 5 -5 of Fig. 5, with the cam-follower and keeper omitted; and

Fig. 7 is a view in rear-side elevation of the kick-out member, including the cam-follower, kick-out spring, and keeper.

The circuit breaker disclosed in the drawings includes a housing, a flexibly mounted power ele; ment functioning as a conductor and contact carrier, a spring-biased kick-out member to move the circuit breaker to open position, a keeper and cam-latch normally locking the circuit breaker in closed position and disengageable by the expansion of the diaphragm of the power element, and a manually operable control lever for resetting the circuit breaker.

The power element herein disclosed is constructed from a thin metal sheet which is folded upon itself to provide two adjacent walls. Intermediate the ends of the member thus for-med, a diaphragm is made by a continuous weld passing around an area enclosed thereby. The walls of the element extend from opposite edges of the of molded insulating material.

diaphragm to form supports by which the element becomes a movable current-carrying part of a circuit breaker. It is desirable both for heat dissipation and to facilitate welding that a portion of the walls immediately adjacent and exterior of the welded seam be spaced to provide an air gap therebetween which will more readily dissipate electro-thermal heat outside of the diaphragm and cause apparent concentration thereof at the diaphragm. At the time of making the continuous weld the diaphragm may be charged with a predetermined amount of water either in liquid or vapor state. Other types of vaporizable charges may be used in place of water.

The housing consists of a base 3 and cover it The base 3 is recessed to provide operating spacefor the circuit breaker and has grooves and projections cooperating with the cover 4 G to provide for positioning of the fixed elements of the circuit breaker. The cover It is removably secured to the base 3 by suitable fastening means, such as rivets, screws or bolts (not shown) and also has projections cooperating with the base 3 to provide guides for the moving elements and supports for the fixed elements.

The power element designated generally at l2 functions as a conductor in the circuit-breaking mechanism, a support for the movable contact, a lever through which the spring-biased kick-out member functions, and also as the means for supplying electro-thermal power for unlatching the kick-out member 50. Such power element 12 is mounted so that it will have movement in the plane of the diaphragm to permit it to act as a lever and as-the carrier for the movable contact 44. Contact is adapted for engagement with and disengagement from afixed contact is.

The power element 12 is held by a mounting terminal 29 which is formed from a strip of metal suitable for electric terminals. The strip is bent to make a square-shaped base as shown and each end projects upwardly above such base at one side thereof. An arm 3! on one-half of one end is in alinement with an arm 33 on the opposite half of the other end. The inner edges of these arms are slightly spaced to provide a slot 35 into which the edge of the power element fits and is held by welding, as indicated at 3?. One welding operation sufiices to secure the terminal 29 and the power element to each other and at the same time to retain terminal 29 in the formed shape illustrated.

When the contacts 44 and 45 are engaged the current flows through the power element !2. When an overload occurs enough additional heat will be generated to trip the diaphragm from the collapsed position shown in Fig. 2 to the expanded position shown in Fig. 3. In order that this lateral expansion of the diaphragm of the power element may be utilized to trip a latching mechanism, the central part of the diaphragm is provided with integral projections 52 fitting in sockets 58 on the kick-out member at.

To provide opening of the contacts 44 and 45 with a snap action the spring-biased kick-out member 50 is pivotally connected to the power element l 2 to normally urge it in a vertically upward direction. The kick-out member 59 is locked in its lowermost position with the contacts closed by a latching mechanism which is tripped by the expansion of the diaphragm of the power element ii. The kick-out member has a pair of legs 5d and 56 which straddle the power element l2 and-are pivotally connected to the diaphragm formed thereon. The leg 54 at its lower end is refiexed to form a spring 39, the lower end of which fits in a slot M in the bottom of the base 8. Spring 39 normally resiliently urges the kickout member 50 and the power element 12 in an upward direction to open the contacts it and 45. Between the lower portion 39* and upper portion 39 of the spring 39 one of the reflexes is flattened and has a projection d3 constituting the keeper of the latching mechanism. Portion 39 of the spring below the keeper #23 is placed under compression when the kick-out member is latched in circuit-closed position and will be referred to herein as the compression part. The portion 39 of the spring 39 above the keeper E3 is temporarily stretched and placed under tension to perform snap closing and will be referred to herein as the tension part.

The kick-out member is formed so that its legs 54 and 56 are biased toward each other with suincient force to maintain proper engagement at the point of pivotal connection with the diaphragm when the latter is collapsed. However, the diaphragm develops sufficient power to flex such legs apart against the inherent resiliency thereof and against any resistance to lateral movement created by the spring 39. When the keeper 43 has moved to the left as the diaphragm expands, with resultant disengagement of keeper d3 from the downwardly facing cam surface 45, the outer edge of the lower offset portion 39 of leg 56 will slide against the flat inner surface 41 of a control lever it. The aforementioned portion 49 of leg tit is formed to provide a cam-followingsurface 59 which engages with and rides on the upper or holding surface iii of the reset cam carried by the control lever to hold the contacts Ml and 455 open while tension is created in the tension part 39 of spring 39 for snap closing.

The control lever i? is rotatably mounted by a trunnion 61 fitting in a bearing 69 in the base 8. To resetthe circuit breaker and manually turn it on and on, such lever has a reset cam with a plurality of camming surfaces best shown in Figs. 5 and 6. The character of these surfaces may be understood by reference to their function and operation during a sequence of operations of the control lever starting from the On position shown in Figs. 1 and 2. In the On position the compression part 39 of spring 39 is held compressed by engagement between keeper 43 and the cam surface 55. In this position there is also tension in the tension part 39 of spring 39 to hold the contacts id and 46 in closed position, and thus insure good contact pressure and provide a desired allowance for wear.

When the power element I2 expands, the keeper 43 is withdrawn from engagement with the cam surface 15 and the force in the compression part 39 of the spring 39 will move the kickout member to the position shown in Fig. 3, thus opening the contacts with a snap action. As the kick-out member moves up, its top engages a fiat area 15 on the control lever l? angled slightly with respect to the lateral axis of the control lever 47. This engagement rotates the control lever 41 from the On position to the Trip position indicated in the broken line of Fig. 1 to visibly in di ate that the circuit breaker has been opened automatically due to overload. As the diaphragm of power element 112 collapses the keeper 43 will move to the right (as viewed in Fig. 3) and bear against the laterally sloping surface 7'! on the reset cam above the cam surface 45.

To move the circuit breaker to On position after automatic opening thereof, the control 5 lever 41 is moved from Trip position to Reset position (see Fig. 5). During such movement the keeper 43 will be forced toward the left as viewed in Fig. 3 by the aforementioned laterally slopin surface 11. When, as a consequence of the continued clockwise movement of the control lever '41, the keeper 43 rides off of cam surface TI and, due to the bias afforded by spring 39, the keeper will snap to the right under the lower cam surface 19, as shown in Fig. 5.

As the control lever 41 is moved from Reset to On position the cam surface 5| being concentric with respect to the axis of trunnion 61 will hold the cam-following surface 49 and the kick-out member in a position with the contacts open. However, the lower cam surface 19, being sloped downwardly from its right end with respect to such axis, will force the keeper 43 downwardly placing the compression part 39 of spring 39 under compression and putting the tension part 38 thereof under tension. When the snap-closing cam surface 8|, extending downwardly from the cam surface 5! to the bottom of the On notch H, comes under the cam-following surface 49 the force in the tension part 39 of spring 39 will cause such cam-following surface to advance the control lever rapidly to On position without the further aid of manual pressure. This imparts snap-closing of the contacts 44 and 46 and places the cam-following surface 49 in the On notch H with the contacts closed under spring tension.

To manually open the circuit breaker, control lever V4'! is moved from On toward Off position. As the Off position is reached the end 83 of the reset cam passes from between the cam-following surface 49 and keeper i3 and the force in the compression part 39 of spring 39 will snap the contacts 44 and 46 open. Immediately upon the release of the keeper 43, the top of the kickout member 50 will hit the flat area 15 of lever 41 and cam the same to the Trip position with the keeper 43 resting on the lateral slope TI. From this position the sequence of operations heretofore described are repeated to again close the circuit breaker.

With the construction as described, a single spring and a single control lever cooperate to snap open and snap closed the contacts of the circuit breaker. This lessens the manufacturing expense, decreases the number of parts subject to wear, and by its simplicity makes the circuit breaker more accurate and sensitive. This construction including the pivoted power element herein disclosed affords a great saving in space.

Although only one embodiment of the invention is shown and described herein, it will be understood that this application is intended to cover such changes or modifications as come within the spirit of the invention and the scope of the appended claims.

I claim:

'1. A circuit breaker comprising, an electrically conductive flexibly supported expansible power element having one end adapted to be connected in an electric circuit, a movable contact carried by the other end of said power element, a fixed contact adapted to be connected in an electric circuit and engageable by said movable contact to close a circuit through said power element, a

spr ng having one end fixed and the other end operatively connected to said power element to urge said contacts open, a keeper on said spring intermediate the ends thereof and dividing said spring into a compression part and a tension Lin part. a cam-follower oneratively associated. with said power element. and a control lever ha n a plurality of camming surfaces engageable with said keeper and said cam-follower to momentarily stretch said tension p rt whil compressing said compression part, said keeper being withdrawn from said camming surfaces upon exmansion of said power element to close said contacts.

2. A circuit breaker as claimed in claim 1, in which one of said camming surfaces has an On notch into which said cam-follower drops to permit the force in said tension part to snap said contacts closed and to maintain pressure therebetween while closed.

3. A circuit breaker as claimed in claim 1, in which one of said oamming surfaces has a sharp decline ending in an On notch, said sharp decline cooperating with said cam-follower to move said control lever to bring said On notch into .alinement with said cam-follower, said On notch being deep enough to remove support from said cam-follower when said contacts are engaged whereby the tension part of said spring holds said contacts closed.

4. A circuit breaker as claimed in claim 1, in which one of said camming surfaces has a slope engageable with the end of said keeper to move said keeper toward one side of said control lever during resetting movement of said control lever.

5. A circuit breaker as claimed in claim 1, in which said control lever is swingable from a Trip to a Reset position preparatory to closing said circuit breaker and then to On position to close said circuit breaker, and said camming surfaces include a lower resetting surface which engages said keeper and compresses said compression part as said control lever is moved from Reset to On position, an upper holding surface which engages said cam-follower to hold said contacts open during part of the movement of said lever from Reset to On position, a declining snapclosed surface which extends from said holding surface and cooperates with said cam-follower to move said control lever into On position with a snap-like action, an On notch at the bottom of said declining snap closed surface deep enough to remove support from said cam-follower with said contacts closed by tension from said tension part when said control lever is in On position, and a lateral slope engaging the end of said keeper in said Trip position and moving said keeper sidewise of said holding surface as said control lever is moved from Trip toward Reset position to bring said keeper to the edge of said holding surface as said lever approaches said Reset position.

6. A circuit breaker comprising, an electrically conductive flexibly supported expansible power element having one end adapted to be connected in an electric circuit, a movable contact carried by the other end of said power element, a fixed contact adapted to be connected in an electric circuit and engageable by said movable contact to close a circuit through said power element, a kick-out member having inwardly biased legs straddling and pivotally connected to said power element and moved apart by the expansion thereof, a spring operable between a fixed end and said kick-out member to resiliently urge said power element to contact open position, a keeper on said spring intermediate the ends thereof and dividing said spring into a compression part and a tension part, a cam follower carried by said kick-out member, and a control lever having a plurality of camming surfaces engageable with said keeper and said cam-follower to stretch said tension part while compressing said compression part, said keeper being withdrawn from said camming surfaces, upon expansion of said power element, to close said contacts.

7. A circuit breaker as claimed in claim 6, in which one of said camming surfaces has an On notch into which said cam-follower drops to permit the force in said tension part to snap said contacts closed and to maintain pressure therebetween while closed.

8. A circuit breaker as claimed in claim 6, in which one of said camming surfaces has a sharp decline ending in an On notch, said sharp decline cooperating with said cam-follower to move said control lever to bring said On notch into alinement with said cam-follower, said On notch being deep enough to remove support from said cam-follower when said contacts are engaged whereby the tension part of said spring holds said contacts closed.

9. A circuit breaker as claimed in claim 6, in which one of said camming surfaces has a slope engageable with the end of said keeper to move said keeper toward one side of said control lever during resetting movement of said control lever.

10. A circuit breaker as claimed in claim 6, in which said control lever is swingable from a Trip to a Reset position preparatory to closing said circuit breaker and then to On position to close said circuit breaker, and said camming surfaces include a lower resetting surface which engages said keeper and compresses said compression par as said control lever is moved from Reset to On position, an upper holding surface which engages said cam follower to hold said contacts open during part of the movement of said lever from Reset to On position, a declining snapclosed surface which extends from said holding surface and cooperates with said cam-follower to move said control lever into On position with a snap-like action, an On notch at the bottom of said declining snap-closed surface deep enough to remove support from said cam-follower with said contacts closed by tension from said tension part when said control lever is in On po sition, and a lateral slope engaging the end of said keeper in said Trip position and moving said keeper sidewise of said holding surface as said control lever is moved from Trip toward Reset position to bring said keeper to the edge of said holding surface as said lever approaches said Reset position.

11. A circuit breaker comprising, an electrically conductive power element adapted to be connected in an electric circuit, a movable contact, a fixed contact with which said movable contact engages to close a circuit through said power element, a spring operably associated with said movable contact to resiliently urge said contacts to open position, a keeper on said spring intermediate the ends thereof and dividing said spring into a compression part and a tension part, a cam-follower associated with said movable contact to cooperate with a holding surface and keep said contacts open, a control member having a camming surface engaging said keeper to compress said compression part and a holding surface to engage said cam-follower to hold said contacts open while said camming surface places 8 tension in said tension part preparatory to snapclosing said contacts, and means operated by said power element to release compression-holding engagement between said camming surface and said keeper to snap-close said contacts.

12. In a circuit breaker having an electrically conductive, expansible power element with one end flexibly mounted and adapted to be connected to an electric circuit, a mounting element for such end comprising a strip of metal bent to form a base with the ends of said strip extending from said base, each of said ends having substantially half thereof removed, and the remaining parts of each such ends being placed in alinement with each other with their edges spaced to form a slot therebetween, the end of said power element being Welded within said slot to secure said elements and make said mounting rigid.

13. A circuit breaker comprising, an electrically conductive flexibly supported expansible power element having, one end adapted to be connected in an electric circuit, a movable contact carried by the other end of said power element, a fixed contact adapted to be connected in an electric circuit and engageable by said movable contact to close a circuit through said power element, a spring having one end fixed and the other end operatively connected to said power element to urge said contacts open, a keeper on said spring intermediate the ends thereof and dividing said spring into a compression part and a tension part, a cam-follower operatively associated with said power element, and a control lever having a plurality of camming surfaces engageable with said keeper and said cam-follower to momentarily stretch said tension part while compressing said compression part, said keeper being withdrawable from said camrning surfaces either manually by movement of said lever or automatically upon expansion of said power element to efiect opening of said contacts,

14. A circuit breaker as claimed in claim 13, in which one of said camming surfa es has an On notch into which said cam-follower drops to permit the force in said tension part to snap said cont-acts closed and to maintain pressure therebetween while closed.

15. A circuit breaker as claimed in claim 13,

v in which one of said camming surfaces has a sharp decline ending in an On notch, said sharp decline cooperating with said cam-follower to move said control lever to bring said On notch into alinement with said cam-follower, said On notch being deep enough to remove support from said cam-follower when said contacts are engaged whereby the tension part of said spring holds said contacts closed.

16. A circuit breaker as claimed in claim 13, in which one of said camming surfaces has a slope engageable with the end of. said keeper to move said keeper toward one side of said control lever during resetting movement of said control ever.

IRVIN W. COX.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,228,956 Heiand Jan. 14, 1941 2,447,032 Shann Aug. 17, 1948

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