US2472233A - Circuit breaker - Google Patents

Description

June 7, 1949.

F. SHORT 2,472,233

CIRCUIT BREAKER Filed Nov. 17, 194s s sheets-sheet 1 F. SHORT CIRCUIT BREAKER June 7, 1949.

3 Sheets-Sheet 2 Filed NOV. 17, -1943 INVENTOR. 'RHN/f SH01? 7".

Arron/vsn June 7, 1949. F. SHORT CIRCUIT BREAKER 3 Sheets-Sheet 3 Filed NOV. 17, 1943 HTTORNEK Patented June 7, 1949 CIRCUIT BREAKER Frank Short, Burke, Va., assignor of one-half to Louis V. Lucia, West Hartford, Co

Application November 17, 1943, vSerial No. 510,635 3 Claims. (Cl. 20G-122) This invention relates to circuit breakers and more particularly to devices intended for automatically breaking an electric circuit when sub'- Jected to an overload.

An object of this invention is to provide a circuit breaker having a current responsive element which is in series with an electric circuit controlled thereby.

A further object is to provide a circuit breaker wherein said element is selectively adjustable to automatically operate the circuit breaker in response to resistance of dilerent amperages in the circuit.

A still further object of the invention is to provide such a circuit breaker having a current responsive element which is adapted to be connected in series with an electric circuit controlled by said breaker and which is selectively adjustable to provide different resistances'in the circuit for operating the breaker when under loads of dierent amperages.

A further object of the invention is to provide an automatic circuit breaker having thermal responsive means acting as a conductor in the electric circuit and operable t'o actuate said breaker when subjected to pre-determined current loads.

A still further object is to provide such a circult breaker which can be installed in conventional types of Wall switch boxes.

Further objects of the invention will be more clearly understood from the following description and from the accompanying drawings in Which- Fig. 1 is a side view in central vertical section of a circuit breaker embodying my invention.

Fig. 2 is a. front plan view of the same removed from the wall box.

Fig. 3 is a front viewin vertical section on line 3-3 of Fig 1 with the latch member and parts of the casing being shown in elevation.

Fig. 4 is a front view in elevation of the casing with some of the current conducting parts mounted therein.

Fig. 5 is an elevational member.

Fig. 61s a front view in elevation of the operating member and adjusting means as connected in an electrical circuit; the said circuit being indicated diagrammatically.

Fig. 7 is a view similar to Fig. 1 but showing plan view of the latch the position of the switch when automatically moved to open position by the current responsive operating member as indicated in dotted lines.

Fig. 8 is a similar view showing the switch when moved to open position by the operation 0f the manually operable member.

Fig. 9 is a fragmental view, in central vertical section, showing a modied form of adjusting means.

As shown in the drawings, my improved circuit breaker comprises a casing 5 of insulating material which may be mounted in any suitable manner Within a conventional Wall switch box such as indicated at'6. The said casing has mounted therein terminals 1 and 8 which extend through the rear wall of the casing and have threaded openings therein to receive binder screws for connecting thereto the ends of conductor Wires of an electrical circuit. The terminal 'I is electrically connected with a contact member 9 and the terminal 8 is similarly connected to a conductor bar I0 which extends to a post II. Another contact member I2 extends to a post I3,

A switch mechanism is provided which consists of a switch bar I4 that is adapted to bridge across and contact the contact members 9 and I2. The said switch bar is carried on an inverted U-shaped rocker bar l5 of insulating material and which is pivotally' supported with its bottom extensions mounted in hook-shaped portions I6 and I1 in the spaced arms I8 and I9 of a cradle having side extensions 2|-2I with trunnions by which the said cradle is journaled in the casing 5 at the pivotal points indicated at 22-22.

The said cradle is provided with an oper-ating handle 23 which extends through a cover plate 24.

A `spring anchoring bar 25 of insulating material is'carried at the ends of resilient supporting members 26l and 27 which are preferably made of spring wire and'anchored respectively on the posts Il and I3. A switch operating spring 28 is secured at one end thereof to a loop portion 29 on the carrier I5 and at the other end to a, loop 30 on the said anchoring bar 25.

A bi-metallic U-shaped operating member 3l is mounted on the posts Il and I3 and is disposed in back of the switch anchoring bar 25 for the purpose to be hereinafter described. Also mounted on said posts, and electrically connected aivaaee in parallel with 'said bi-metallic operating member, I provide a resistance in the form of a helical coil 32 having an adjusting screw-33 which is threaded thereto and has a disk-shaped head portion 34 whereby it may be rotated. The rim of said portion 34 may be provided with an indicating line 35 which cooperates, as will be hereinafter described; with indicia on a scale 36 that is carried on the post I3. Stop members 3'! and 38 may also be mounted on said posts Il and I3 for limiting the movement of the carrier I5.

A latch member 39, preferably also of insulating material and having a detent 43, is pivoted within recesses 4I4I in the casing 5. Spaced spring members 42-42 are secured to the said latch member, underlie the same and engage the front plate 24 to retain the latch within said recesses and urge it towards its operating position with relation to the anchor bar 25.

The said latch member 39 is provided withan extension 43 which projects through an opening 44A in the front plate 2li to serve as an indicator,

and it may also be used as a re-setting handle as will be hereinafter described.

A latch operating member 45 is pivotally mounted at 46 to the handle 23 and provides fingers which swing freely from said handle for operating the latch 39 as will be also hereinafter described.

When the above described circuit breaker is connected to an electrical circuit, the bi-metallic operating member 3 I together with the resistance 32, are connected in series in said circuit and, as illustrated in Fig. 6 of the drawings, the said circuit includes the switch I4, the contact members 9 and I2, a source of energy i1 and resistances 48--48 which represent'dierent appliances that may be connected to said circuit.

The operation of my improved circuit breaker will now be described.

When the circuit breaker is in its closed position, as illustrated in Fig. l, the electric current may flow from the terminal 'I to the contact 3,'

through the switch bar Iii to the contact I2 and to the post I3, through the iJ-shaped bi-metallic member 3l and the resistance coil 32 to the post I l, and through the conductor I3 to the binding post t. The said bi-metallic member 3i and resistance 32 are connected in parallel and constructed to carry current up to a certain predetermined amount of amperage through the circuit. "Iherefore, should an overload above such amperage occur in the circuit, the resistance in the said bi-metallic member 3i will cause it to heat and warp in the direction of the spring anchoring bar 25, as indicated in dotted lines in Fig. 7, and force the said anchoring bar outwardly until the anchoring point of thespring 28 has been moved past the pivotal point of the switch carrier I in the hook portions Il. At this time, the said carrier will be rocked on its pivots and moved to the position shown in Fig. 7 wherein the switch bar i4 is spaced from the contacts 9 and l2 and thereby breaking the electrical circuit.

' As the switch mechanism is moved to the open position by the above operation, the bar 25 will move past the detent 40 and the latch 39 will be forced upwardly, by the springs'42-42`, moving said detent in the path of the return movement of said bar. After the circuit has been broken, the bi-metallic member 3| will cool and return to its normal position, leaving the said anchoring bar 25 in engagement with the detent 40 against the tension of the spring members 26-21 It will be noted that the extension 43 on the latch 39 is now in its up position. This will indicate, from tion shown in Fig. 1.

the exterior of the plate 24, that the switchris open and that the circuit has been broken due te the occurrence of an overload.

The above described circuit breaker may be re-set by simply moving the handle 23 downwardly to the position illustrated in Fig. 8. The downward movement of the handle 23 will cause the fingers 45 to move the latch 39 downwardly and disengage the detent 40 from the bar 25; thus allowing the said bar to be returned, by the spring members 26-2'i, to its re-set position which is also the normal on position of the circuit breaker.

After the circuit breaker has been re-set, the

switch mechanism may be moved to its closed or "on position by moving the handle 23 to the posi- This will carry the hook portions I1-I I to the position wherein the pivotal points of the carrier I5 are at the opposite side of the axis or center of the spring 28 and thus causing the said spring to urge the carrier into switch closing position.

It will be noted that, while the anchoring bar 25 is in its normal position, the circuit breaker r `y be operated to the on or off positions in if. same manner as any ordinary switch. Howe when the said anchor bar has been forced to ti. position illustrated in Fig. 7 by an overload in the circuit, the switch cannot be closed until the lever 23 is iirst moved downwardly to the re-set position and then upwardly to the position shown in Fig. l.

My improved circuit breaker may also b'e re-set by simply forcing the extension 43 downwardly since this will disengage the bar 25 from the detent 40, cause the said bar to move to its normal position and carry the axis oi the spring 28 past the pivotal point of the carrier I5. This, however. will also cause the said spring 2B to swing the said carrier and iiove the switch bar I4 to the circuit closing or on position.

It will be noted that the switch mechanism of my improved circuit breaker cannot be moved to its circuit closing position until the circuit breaker has rst been re-set by the downward movement of either the lever 23 or the extension 43. This will assure an indication that the circuit has been broken through the automatic operation of the circuit breaker on account of an overload in the circuit. Indication, of the automatic operation of the circuit breaker due to an overload, is also provided, while the circuit is dead, when the operating handle 23 is in its on position and also when the extension 43 is in its raised position, as' illustrated in Fig. 7.

Adjustability of the above described circuit breaker is obtained by means of the resistance coil 32 and the screw 33 which may be turned in said coil until the indicating line 35 thereon is in register with the iigure on the scale 36 that corresponds to the amperage at which it is desired to have the circuit breaker operate for automatically breaking the electric circuit.

Assuming that the resistance of the bi-metallic member 3l is such that it takes a current flow of three amperes before it will heat to a temperature which will cause it to operate the bar 25, it will be readily understood that, when the screw 33 is positioned in the coil 32 so that the indicating line 35 registers with 5 on the scale 36, the effective length of the said coil will be such that it will have a current carrying capacity of two amperes; thus a total of live amperes iiowing through the circuit will cause the bi-metallic bar 3| to flex and operate tobreak the circuit as above described and illustrated in Fig. 7. When the screw 33 is set so that the line 35 is in register with the figure 30 on the scale 36, the coil 33 will have a lesser effective length which will decrease its resistance to the current so that it will have a current carrying capacity of twenty-seven amperes and therebyl raise to thirty amperes the amount of current required in the circuit in order to heat the member 3| suiciently to cause it t0 operate. It is pointed out that since the coil 32 and the member 3| are connected in parallel, the amount of current fiowing through the bi-metallic member 3| is in direct proportion to the resistance in the coil 32, which is controlled by the effective length thereof. Therefore, any change in the resistance of the coil 32 will also proportionately change the amount of current flowing through the member 3| and thereby render the said member operable under overloads of different 'intensities.

It will be understood, from the foregoing description, that I have provided simple and highly effective means whereby a circuit breaker, such as above described, may be selectively adjusted to operate under overloads of diiferent pre-determined intensities. This is of particular advantage since it provides for accurate and speedy calibration during the production of circuit breakers.

As shown in Figs. 7 and 8, means are provided for retaining the cradle 2| in the on and oil positions. Such means may comprise a spring 49 which is suitably mounted, such as on the cover 24, and is adapted to engage a boss 50 on the said cradle with an over-center action and exert a tension on said boss urging the cradle 2| to the opposite limits of its movement.

My invention may also include adjusting means, such as shown in Fig. 9, wherein an adjusting screw 5 I, having a lock nut 52, is threaded to the bar 25 and engages the bi-metallic member 3|; thus providing a calibrating adjustment which, if desired, may be used in conjunction with or in lieu of the resistance adjustment which includes the coil 32.

My improved circuit breaker is highly desirable as a protection for the regular fuses in an electric circuit since it can be installed in the circuit with said fuses and, by adjusting the circuit breaker so that it will automatically operate at just below the amperage of the regular fuses, an overload in the circuit will cause it to be broken before the said fuses are blown and thus provide an opportunity to repair the defect or remove the overload from the circuit before damage has been caused to the regular fuses.

I claim:

1. A circuit breaker including a casing, electric contact members mounted in said casing. a switch bar cooperating with said contact members, a carrier for said bar, a carriage pivotally supporting said carrier, a spring member connected at one end of said carrier and at the opposite end to an anchoring member movable to carry the axis of said spring across the pivotal axis of said carrier, a current carrying member responsive to an overload in said circuit for operating said anchoring means to cause said spring member to move said switch mechanism to open circuit position, a latch member having a detent for engaging said anchoring means to retain said switch mechanism in open position, means for manually operating said carriage to move the pivotal point of said carrier to the opposite side of said spring member, means operable with said carriage for moving said latch to release said anchoring means, and means urging said anchoring means toward their normal position.

2. An electric circuit breaker including a casing, contact members mounted in said casing, a switch bar cooperating with said contact members, a carrier for said switch bar pivotally supported at one end thereof within a movable seat, a spring member secured to said carrier, anchoring means'for said spring member, manually operable means for moving said seat to cause movement of said carrier by said spring into circuit closing or breaking position, current carrying means in series with said switch and responsive to overloads in said circuit for moving said anchoring means to cause operation of said switch to open circuit position, a detent for retaining said anchoring means against movement to normal position, and means on said manually operable member for causing said detent to release said anchoring means and thereby re-set said switch.

3. An electric circuitbreaker of the character described comprising a casing having a front plate a switch mechanism mounted in said casing, said mechanism including a switch bar, a carrier for said bar, a spring for operating said carrier, anchoring means for said spring, means for plvotally supporting said carrier by one end thereof I Number and adapted to move the pivoted end across the axis of said spring to cause operation of said carrier into circuit closing and opening positions, said anchoring means being movable from a normal position at one side of the pivotal point of said carrier to a position at the opposite side thereof. a detent for preventing return of said anchoring means to said normal position, and an extension on said detent projecting through said front plate for indicating the condition of said breaker and operable to release said anchoring means and position.

FRANK SHORT.

imiannENclazs crrEn The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date 1,531,722 Adams Mar. 31, 1925 1,550,206 Church Aug. 18, 1925 1,722,768 Schnetzler July 30, 1929 1,759,395 Getchell May 20, 1930 1,793,954 Myers Feb. 24, 1931 1,872,122 Cook Aug. 16, 1932 1,928,802 Wight Oct. 3, 1933 1,946,894 Brogger Feb. 13, 1934 1,966,051 Sperry et al. July 10, 1934 1,969,064 Field Aug. 7, 1934 2,092,327 Persons Sept. 7, 1937 2,123,063 Peters July 5, 1938 2,170,426 Raney Aug. 22, 1939 2,283,736 Jackson Mar. 19, 1942 2,368,620 Runke -..1--.. Nov. 6, 1945 permit return thereof to normal

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