US2467745A - Circuit breaker - Google Patents

Description

April 19, 1949. J. w. HARRISON 2,467,745

CIRCUIT BREAKER Filed June 2'7, 1944 2 Sheets-Sheet 1 I III. I I 37 51 ATTORNE April 1949- J. w. HARRISON 2,467,745

V CIRCUIT BREAKER Filed June 27, 1944 2 Sheets-Sheet 2 113 103 101 9 V 7 "109 $57? 19 ii :3; 3352- INVENTOR Ja/m W Harrison.

Patented Apr. 19,1949

CIRCUIT BREAKER John W. Harrison, Mansfield, Ohio, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 27, 1944, Serial No. 542,342

1 4 The invention relates to circuit breakers and, more particularly, to manually and automatically operable small air circuit breakers for controlling and protecting electrical circuits.

An object of the invention is to provide a double-throw circuit breaker for selectively controlling a plurality of .circuits wherein the contacts are automatically opened by snap-acting bimetal elements and are arranged to be tripfree of the manual operating handle so that they cannot be held closed against overload currents.

Another object of the invention is to provide a double-throw circuit breaker having a common operating member for selectively closing any one I of a plurality of isolated circuits wherein the contacts for each circuit are automatically opened by a snap-acting bimetal element irrespective of the position of said common operating member.

Another objectof the invention is to provide an improved double-throw circuit breaker for controlling a plurality of circuits wherein a current-responsive snap-acting bimetal element is associated with each circuit for automatically opening the contacts of the associaed circuit and an operating handle operable to move said bimetal elements to selectively open and close said circuits.

Another object of the invention is to provide an improved circuit breaker for selectively controlling a plurality of isolated electrical circuits wherein the contacts for each circuit are automatically opened by separate snap-acting bimetal elements and are selectively opened and closed by a common manual operating member which is biased to a neutral open position by separate biasing means.

Another object of the invention is to provide a manually and automatically operable doublethrow circuit breaker of simple and inexpensive construction.

The novel features that are considered characteristic of the invention are set forth in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description thereof when read in conjunction with th accompanying drawing, in which:

Figure 1 is a vertical sectional view of a circuit breaker embodying the principles of the invention;

Fig. 2 is a vertical sectional view taken on line IIII of Fig. 1;

Fig. 3 is an exploded view partly in sectionshowing the construction of the operating handle and the biasing means therefor;

Fig. 4 is a reduced sectional view of the circuit breaker showing the handle in the "011 position and the bimetal switch members in the open position;

6 Claims. (Cl. 200-3) Fig. 5 is a reduced sectional view similar to Fig. 4 but showing the handle in the neutral position at the instant after one of the bimetal switch members has operated to open the contacts and before the bimetal element has cooled;

Fig. 6 is a sectional view taken on line V IVI of Fig. 2 showing the construction of one of the actuators;

Figs. 7 and 8 are elevational views of a modified embodiment of the operating handle;

Fig. 9 is a vertical sectional view illustrating a modification of the invention wherein the contact structure is non-trip free of the handle showing the breaker in the closed position;

Fig. 10 is a viewsimilar to Fig. 9 but showing the bimetal element snapped to open the contacts but held closed by the handle;

Fig. 11 is a view similar to Fig. 9 showing the breaker in the open position; and

Fig. 12 is a plan view of the non-trip free spring.

Referring to Figs. 1 and 2 of the drawing, the circuit breaker comprises a casing H of molded insulating material and a cooperating cover I! also of molded insulating material which is removably secured to the casing II. A pair of terminal conductors l5.and II project through the casing H and have stationary contacts is and 21 respectively secured to the inner ends thereof. The other ends of the terminal conductors extend outside of the casing for connecting the breaker in an electrical circuit. There are two sets of terminals mounted in the casing Ii, only one, 23, of the second set being shown (Fig. 2), and two sets of stationary contacts, only one, 25, of the second set being shown. The sec- 1 0nd set of terminals and the associated contacts are mounted adjacent to but separated from the terminals l5-ll and the corresponding contacts I 9-2I by a partition wall 26 molded integral with the casing H which completely isolates the two circuits.

The two sets of stationary contacts are adapted to be selectively bridged by movable contacts 21 and 29 mounted on a movable bimetallic switch member 3|, and contacts 33 and 35 mounted on a movable bimetallic switch member 31. The switch members 3| and 31 comprise sections from a bimetallic disk and have the characteristic of moving with a snap action from either one or the other of two opposite or reversely flexed positions without having an intermediate fixed position.

The movable switch members 3| and 31 are disposed in separate compartments formed by the partition wall 28 molded integral with the casing and are movably supported at their centers on headed rods 39 and 4|. The switch members are biased outwardly away from the stationary contacts by means of coil springs 43 and 45. The springs 43 and 45 respectively surround the rods 38 and 4|, and are compressed between counterbored spring seats in the casing and the heads of their associated rods 39-4l.

A pivoted operating member 41 of molded insulating material is provided with spaced integral projections 49 and 5|, and an integral operating handle 53. The projections 49 and 5| are adapted to cooperate respectively with V- shaped recesses 55 and 51 in the bimetallic switch members 3| and 31 to effect manual opening and closing of the contacts. The operating member 41 is pivotally supported on pins 59 supported in bearings 6| set into the side walls of the casing, there being a pin 59 extending inwardly from each side wall. The heads of the pins 59 are hexagon and fit within suitable openings in the side walls of the casing to prevent rotation of the pins. The pins 59 extend through central openings in actuators 63 and 65, and into a central opening in the operator 41, thus pivotally supporting the operator 41 and the actuators 6365.

Mounted in recesses 61 and 69 in the actuators 5365 respectively are coil springs 1| and 13. The projecting ends and 11 of the springs 1 |-13 extend into offset portions of their respective recesses 61--69, and the ends 19 and BI of the springs engage elongated slots 83 in their associated pins 59 which, being held against rotation, anchor one end of each of the springs ll-13. The operator 41 is provided with projections 85 and 61 on the opposite ends thereof which cooperate with opposing shoulders 89 and 9| on the actuators 63 and 65, respectively.

The actuators 63 and 65 are provided with projections 93 and 95 respectively which engage projections 91 and 99 integral with the side walls of the casing and extending inwardly therefrom to, limit the extent of movement of the actuators. An initial tension may be given thespring's 1| and 13 by rotating the pins 59 in the proper direction and then inserting the heads of the pins in the recesses in the casing to prevent unwinding of the springs.

The operation of the circuit breaker is described as follows: Assuming that the operator 41 is in the on position as shown in Fig. l with the contacts 2129 in engagement with the stationary contacts |9-2|, upon the occurrence of an overload current in the circuit comprising the terminal I5, contacts |9-2|, bimetallic switch member 3|, contacts 2l- -29, and the terminal H, the bimetallic member 3| becomes heated and, when heated a predetermined amount, suddenly I. to

snaps to the oppositely flexed position in which it appears in Fig. 5. When the bimetallic element 3| snaps to the Fig. 5 position, the ends thereof strike portions ||I| molded integral with the casing H and the V-shaped recess in the bimetallic element disengages the projection 49 on the operator, whereupon the spring 1| (Fig. 3), acting through the actuator 63 and the projection 85 on the operator 41, moves the operator to the center or neutral 03 position (Fig. 5). When the bimetallic element 3| snaps to the Fig. 5 position, the central portion thereof which is in engagement with the head of the rod 39, moves the rod downwardly compressing the relatively weaker spring 43. The bimetallic switch member remains in this position (Fig. 5) until it cools a predetermined amount, at which time it snaps to the reversely flexed position, but, since at this time, the operator 41 is in the neutral 0 position, the spring 43 expands and moves the bimetallic element 3| upwardly to the position in which it is shown in Fig. 4.

From the neutral ofi" position, the operator 41 may be moved to either ofthe on positions to selectively close either of the circuits. Movement of the operator 41 in a clockwise direction from the oil position, engages the projection 5| on the operator with the bimetallic switch member 31 moving the member inwardly to engage the contacts 33-35 with their correspond- .ing stationary contacts. Near the end of the movement of the operator, the projection 5| engages the V-shaped recess 51 in the bimetallic switch member 31 to retain the operator 41 in the on position, and also to place the switch member 31 under tension and to restrain the 'switchgmember in the closed contact position.

Movement of the operator from the ofi position to one of the on pbsitions tensions one of the springs 1| or 13, depending on the direction of movement of the operator. If, for instance, the operator is rotated counterclockwise from the Fig. e position in order to actuate the switch member 3| to closed position, the projection 85 on the operator engages the shoulder 89 on the actuator 63 and rotates the actuator there-.

with. Since the end 19 of the spring 1| is engaged in the slot 83 in the pin 59 which is held against rotation, the rotation of the actuator 63 tensions the spring 1| so that, upon automatic operation of the bimetallic switch member 3|, the spring will return the operator '41 and the handle 53 to the neutral ofl position. Movement of the operator in a counterclockwise di; rection does not displace the actuator 65 or tension the spring 13 since the shoulder 81 on the operator 41 moves away from the actuator 65,

the initial tension of the spring 13 biasing the projections 95 against the limit stop 99. Simi-L larly, upon clockwise movement of the operator 41 from the neutral position, the projection 81 on the operator 41 engages the shoulder 9| on the actuator 65 and rotates the actuator 65 to tension the spring 13 without disturbing the actuator 63 which is limited in its clockwise move ment by the projection 93 thereon eng the limit stop 91. Thus, when the operator is released from either on position, it is quickly actuated to the ofi position by the reactive force of one of the springs unopposed by the force of the other spring until the operator reaches the ofl position. At this point the first spring action is stopped by the actuator striking the projection 91 or 99 andv the other spring acts as a shock-absorber to prevent overtravel of the operator, the two springs 1|13 and the actuators 63-65 cooperating to restrain the operator and the handle in the off position.

springs I93 are disposed between an operating member I95 and the bimetallic switch members 3| and 31. For illustrative purposes only the bimetal 3| is shown in Figures 9, 10 and 11 but it will be understood that the modifications are the same for both poles of the double-throw breaker. The operating member I05 is provided with a handle I01 and is supported and operated Certain parts shown in Figs. 9,

in the same manner as was previously described for the Fig. 1 modification. The spring I03 is provided with insulating buttons I09 bearing against the upper surface of the bimetal element 3| at points near the ends thereof. The spring I03 is provided with an elongated rectangular slot HI (Fig. 12) through which extends a projection H3 on the operating member [05. The end of the projection H3, in the closed position of the handle, engages the V-shaped notch 55 in the bimetal element 3| to hold the bimetal element and the contacts in the closed position and to retain the handle in the on position. The operating member is also provided with projections H disposed one on each side of the projection I I3 and radially shorter than the projection H3. The projections H5 engage the mid-portion of the spring I03 on each side of the slot I l l to maintain the spring under tension and hold the contacts closed when an overload occurs and the handle is held in the on position.

Assuming that the circuit breaker is in the closed position (Fig. 9) and that normal current is flowing through the closed circuit, the operation of the device is described as follows:

Upon the occurrence of an overload current in the closed circuit, the bimetal 3! becomes heated and when heated a predetermined amount snaps over to the position shown in Fig. 10. Since the handle is not held in the on position, the spring H or 13 (Fig. 1), depending on the afiected circuit, acts to move the handle to the "01? position (Fig. 11) as soon as the V-shaped notch 55 frees the projection H3. At the same time, the spring 43 or 45 expands to move the corresponding bimetal element 3i or 31 and the associated spring I03 to the open contact position as shown in Fig. 11.

Should it be desired to maintain the circuit closed during the existence of an overload current the handle I0! is held in the closed position (Fig. In this event the bimetal element will, when heated a predetermined amount, snap to the position in which it is shown in Fig. 10, but, since the spring I03 is of greater strength than the spring 43, the contacts will be held closed even though the bimetal has snapped to its off position. When normal current value is restored to the circuit the bimetal cools and resumes the position shown in Fig. 9.

The two bimetallic switch members 3| and 31 may be arranged to automatically open its corresponding circuit and release the actuator at different values of overload currents, if desired. For example, the double-throw circuit breaker of the instant invention may be used for controlling a lighting system arranged to give either bright or dim lighting. If, for instance, the bright lights require amperes and the dim lights require only 10 amperes, the wire of the dim light circuit may be smaller than the wire for the bright light circuit, and each bimetallic element will be chosen to cause opening of the breaker when the safe current for its particular circuit is exceeded.

Having described the invention in accordance with patent statutes, it is to be understood that various changes and modifications may be made in the structural details disclosed without departing from some of the essential features of the invention. It is, therefore, desired that the language of the appended claims be given as reasonably broad an interpretation as the prior art permits.

I claim as my invention:

1. In a circuit breaker for controlling either one of two circuits comprising a casing of molded insulating material having a partition wall therein forming separate compartments for completely isolating said circuits, a set of spaced stationary contacts disposed in each compartment, a separate switch member in each compartment comprising a thermally-responsive snap-acting bimetal element disposed for movement in parallel planes and operable when heated a predetermined amount to. snap from one position to another to cause automatic opening of the related contacts, pivoted manual means comprising a handle of one-piece molded insulating material extending across said compartments and having projections molded integral therewith disposed one in each compartment for engaging and operating said switch members to open and to selectively close said sets of contacts, and detent means on each of said switch members for engaging said projections to releasably restrain said handle in the corresponding closed position.

2. In a circuit breaker for selectively controlling a plurality of circuits comprising a casing of molded insulating material having a partition wall therein forming separate compartments for isolating said circuits,.relatively movable contact means in each compartment, a separate switch member for each set of contacts comprising a thermally-responsive snap-acting bimetal element disposed in each compartment for movement in parallel planes and operable when heated a predetermined amount to snap from one position to another to cause automatic opening of the related contact means, manual means comprising a pivoted operator of one-piece molded insulating material extending across said compartments, and projections molded integral with said operator disposed one in each compartment and spaced radially about said operator for engaging and operating said bimetal elements to open and to selectively close said circuits.

3. A circuit breaker for selectively controlling a plurality of isolated circuits comprising a plurality of sets of stationary and movable contacts, means insulating each set of contacts from each other set of contacts, a switch member for each of said sets of contacts disposed in spaced parallel relation and operable to selectively close said sets of contacts, manual means comprising an operating member having axially and radially spaced projections thereon for engaging and operating said switch members, detent means formed in axial alignment on said switch members for engaging said spaced projections to releasably restrain said handle in engagement with the corresponding switch member, and each of said switch members comprising a snap-acting bimetallic element heated in response to overload currents in the associated circuit and operable when heated a predetermined amount to cause automatic opening of the corresponding contacts and release of said handle.

4. A circuit breaker for selectively controlling a plurality of isolated circuits comprising a plurality of sets of separable contacts, means insulating each of said circuits from each other circuit, operating means comprising a handle of one piece molded insulating material operable in either direction from a neutral open" position to a closed position to selectively close said sets of contacts, individual means biasing said handle in each direction to said neutral open" position, electroresponsive means for each circuit disposed for movement in spaced parallel planes andoperable in response to overload currents in the related circuit to cause automatic opening of the related set of contacts, axially spaced projections molded integral with said handle, said projections being also spaced radially on said handle for engaging and operating said electroresponsive means, and axially ali ned detent means formed on said electroresponsive means for engaging said projections to releasably restrain said handle in the corresponding closed position.

5. A circuit breaker for selectively controlling a plurality of isolated circuits comprising a casing 01 molded insulating material having a partition forming separate compartments extending the length of said casing, a plurality of sets of separable contacts disposed in said separate compartments, operating means including a handle of one piece molded insulating material extending axially across said compartments and operable in either direction from a neutral "open position to a closed position to selectively close.

said sets of contacts, electroresponsive means disposed in each of said compartments operable in response to overload currents in the related circuit to cause automatic opening of the related contacts, axially and radially spaced cam members molded integral with said handle and disposed one in each of said compartments for engaging and operating said electroresponsive means to selectively close said sets of contacts, said electroresponsive means in the closed position thereof cooperating with the associated cam members to restrain said handle in the closed position and operable upon automatic opening of said contacts to release said handle, and separate spring means disposed in each of said compartments for returning said handle to the neutral open position upon release thereof.

6. A circuit breaker for selectively controlling either one of two isolated circuits comprising two independent sets of spaced stationary contacts, separate connecting means for connecting each set of spaced stationary contacts in one of said isolated circuits, separate switch members one for each set of contacts comprising thermallyresponsive snap-acting bimetal elements disposed for movement in spaced parallel planes and operable when heated a predetermined amount to snap from one position to another to cause automatic opening of the related contacts, manual means comprising a handle having axially and radially spaced projections thereon for engaging and moving said elements to open and to selectively close said sets of contacts, detent means formed in axial alignment on said bimetal elements for alternately engaging said spaced pro- Jections to releasably restrain said manual means in the corresponding closed position, and spring means intermediate at least one of said bimetal elements and said manual means for maintaining the associated set of contacts closed irrespective of the position of said bimetal element when said manual means is held in the closed position during the existence of an overload current.

JOHN W. HARRISON.

REFERENCES CITED The following references are of record in the fife of this patent: Q

UNITED STATES PATENTS Von Hoorn Jan. 16, 1945

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