US2677734A - Electric circuit breaker - Google Patents

Description

May 4, 1954 w. D. BoLLER Erm. 2,677,734

ELECTRIC CIRCUIT BREAKER Original Filed June 10, 1948 2 Sheets-Sheet l M 3 n f C Wulff/4 Aw. l, W 1 CIMM! l Wm Mw www." w F x Im W E w wf: Y t

Avrorzusys May 4, 1954 w. D. BOLLER l-:T AL

ELECTRIC CIRCUIT BREAKER 2 Sheets-Sheet 2 Original Filed June l0, 1948 mw /A Patented May 4, 1954 UNITED STATES ATENT OFFICE ELECTRIC CIRCUIT BREAKER William D. Boiler, Milfor d, Ohio, Warren D. Berkley, Fort Wayne, Ind., Waiter Ernst, Dayton, 01110, and Edwin W. Landmeier, Covington, Ky., assignors to The Wadsworth Electric Mfg., Co., Covington, Ky., a corporation of Kentucky (Cl. 20G-88) 3 Claims. 1

rThis invention relates to circuit breakers, and is', concerned primarily with a circuit breaker intended to control the circuits in homes and comparable places.

This application is a division of our United States patent application Serial No. 32,204, which was. iiled June 10, 1948, for Electric Circuit Breaker, and which is now issued as United StatesPatcnt No. 2,618,716.

At the present time, the electrical installations for: homes, business establishments, and other places making use of the current. supply that is made available by the electric. companies includes one or more circuits, each of which embraces a ruse and sometimes a switch associated therewith. When the circuit is overloaded or a short circuit develops, the fuse burns out in a well-known manner and must be replaced before service can be restored.

The present invention has in view as its foremost objective the provision of a circuit breaker which is intended to replace the fuse and switch heretofore employed in controlling such circuits.

Under practical conditions, a plurality of circuits are ordinarily included in electrical installations of the type with which this invention is concerned and a further object of the invention is the provision of a circuit breaker which is susceptible of being assembled in multiple or gangs with each unit controlling one circuit.

In the known combination units of the type intended to be improved by this invention, it has been the practice to provide a pair of contacts for controlling the circuit. When these contacts are engagement, the circuit is closed and when they are spaced apart, the circuit is open. 'Usually one of these contacts is iixed and the ooher is movable. The present invention has in view as an important object the provision of a circuit breaker of the type indicated in which both oi the contacts are movable. This arrangement presents certain definite advantages. It is possible to provide for the movement of one Contact into opened or closed position under the influence of a manually operable lever while the other contact is placed under the control of the circuit conditions so as to. befmoved into opened position. under overload or short circuiting conditions. This latter Contact may be moved back into circuit closing position under the. influence of themanualiyoperable lever. a

The problem of eliminating arcing in a circuit breaker of this type has long been recognized by those skilled in this art. When the; two contacts move apart an arc is created due to ionization of the air and numerous and varied attempts have been made in devising means for eliminating this arcing. The present invention has in View as another highly important object the provision of new and improved means for eliminating the arcing. In achieving this end, a permanent magnet is employed and is located in close proximity to the movable contacts. This permanent magnet has a magnetic strength that is sufficient to ce effective on the arc which is created by the break of the contacts. This arc will depend cn the current and speed at which the contacts are moved apart. Thus, when the contacts move apart any are which might be created is drawn to the permanent magnet and eliminated. This action is characteristically different from those devices which operate on the principle of snuiiing out the arc by depriving it of air.

To the end of keeping the contacting surfaces clean a further object of the invention is the provision oi a circuit breaker of the type indicated in which the contacts are separated with a wiping action in contrast to a direct pull apart.

Another object of the invention is the provision of ber shielding on the casing structure immediately about the arc suppressing magnet. This shielding accommodates the formation of carbon deposits on the interior oi' the casing and cover.

Various other more detailed objects and advantages of the invention such as arise in carrying out the above noted ideas in a practical embodiment will in part become apparent and in part be hereinafter stated as the description of the invention proceeds.

For a full and more complete understanding of the invention reference may be had to the following description and accompanying drawings wherein:

Figure l is a longitudinal vertical section through a circuit breaker designed in accordance with the precepts of this invention and showing the unit in manually closed position;

Figure 2 is a sectional View similar to Figure 1 showing the unit in the manually opened posiion;

Figure 3 is another view similar to Figures 1 and 2' showing the unit in the opened position as caused by circuit conditions;

Figure e is a vertical section taken on a plane normal to the showing of Figures 1, 2 and 3;

Figure 5 is an enlarged detailed view showing the rocker carrying one of the contacts in plan and the casing in section; and

Figure 6 is another detailed view taken on a horizontal plane as represented by the line S- on Figure l.

The preferred embodiment of the invention is illustrated in Figures 1 to 6, inclusive. In these views there is shown a casing which is referred to in its entirety by the reference character C and which is made from an appropriate material having good insulating properties and which is susceptible of being molded into the desired structural formation. There are available on the public market many synthetic plastics which will fulfill these qualifications. Among these is the phenol condensation product known as Bakelite.

The casing C comprises a main side wall Iii, a top wall il, a bottom wall I2, and end walls i3 and ifi which are spaced inwardly from the end edges of the side wall I0. All of these walls are integrally joined and the completed structure provides free end portions of the side wall it which are represented at I5 and IE and immediately beneath which are the thickened wall struc'I tures I7 and I8.

The end wall I3 is formed with a slot IS which denes an outer panel which is relatively long and the end edge of which is spaced from the thickened wall structure I'I. This slot i5 also defines an inner panel 2I which is relatively short and the end edge of which defines an opening at 22. A terminal plate 23 is formed at one end with an inclined the slot I S. This terminal plate 23 is also formed with a neck Z5 which is countersunk in a recess formed in the thickened wall structure Il This neck 25 is interiorly threaded as represented at 2S to accommodate a binding post. The thick ened wall structure Il is also provided with a recess 2l beneath the threaded bore 26 to allow for screwing the binding post (not illustrated) home. p Referring now to the thickened wall structure I8 and. end wall I4, it will be noted that these two elements are spaced apart by an irregularly shaped slot 28. The wall structure I3 is formed with a recess 2i? that is counterbored as indicated at 3c. Another terminal plate BI has a neck that is received in the counterbore 3@ and the bore of which is threaded as indicated at the threaded bore being located opposite to the recess 29. The threaded bore 33 and recess Z9 ae commodate another binding post. The terminal plate 3i is formed with an irregularly shaped part 3d that corresponds to and is received in the slot 28. integrally connected to this part 34 is a flange 35 which is positioned within the chamber enclosed by end walls i3 and Ill.

An adjusting screw 36 is received in a passage 3i formed in This screw de has a head 38 which is positioned within enlarged recess 3.9 that communicates with the bore 3l'. This head 38 may be slotted to accommodate a tool such as a screw driver.

The thickened wall structure I5 is formed with a recess lf3 which communicates with the inner chamber of the casing and the bore The adjusting screw 36 extends into this recess and immediately adjacent to the thickened. wall I-8 is formed with an annular groove 4l which re ceives a washer 42. This washer 4.2 and the head hold the screw 36 against longitudinal movement. The free inner end of the screw 36 is threaded and screwed into an opening 43 formed in the flange and also into an opening 44 formed in the end portion 45 of a bimetaliic thermostat de, this end portion 45 being offset from the main part of the bimetallic thermostat flange 24 which is received in the thickened wall structure I?.v

' which the bimetal le passes.

4 by a shoulder di'. It will be noted that this end portion snugly engages the flange 35 of the terminal plate and is spot welded thereto.

Extending inwardly from the end wall I4 into the inner chamber are a pair of lugs 4S and 49 which are integrally formed with the wall I4. The opposing corners oi these lugs lli and i9 are cut away to provide recesses which receive a rupture magnet ed. This magnet 59 is of the U-shaped cross-section illustrated in Figure 6 and has legs iii and 52, the outer faces oi which are imbedded in the side wall. Ii] and cover to be later described. These side legs .ai and 52, together with the base, denne a recess through It is evident that current passing through the bimetal :i6 will be eiiective on the rupture magnet iii) to vary the strength thereof for circuit rupturing purposes as will he later described.

A keeper piece 54 has its lower end anchored to the end part 45 of the binietal 46 in any preferred manner such as by being spot welded thereto. The upper end of this keeper piece takes the form of a hook 55, to the bill of which overlaps the end of the bimetallic thermostat 4B. A latch member 56 which also functions as an armature for the magnet 5t is secured to this keeper piece 54. This latch member 5t is made from a metal having the .required magnetic properties and it will be noted that a detent 5l' is struck therefrom as by a metal stamping operation. The anchorage between the latch 56 and the keeper piece 54 is effected by punching a pair of recesses 58 in one face of the latch 5%. This forms small protuberances 59 on the opposite face. The keeper piece 54 is formed with openings which receive these protuberances 553. After the protuberances 59 pass through the openings they are peened over to form what are in effect rivet heads 5B.

The bottom wall I2 is formed with an inclined surface at 6i which opens into the inner chamber and which terminates at its lower end in a shoulder 62. A permanent magnet 63 of U-shaped formation has its base received on the inclined surface 6I. The side legs of the magnet 63 have outer faces which are received in recesses 64 and 65 formed in the casing and cover, respectively. Also, fitted in these recesses and surrounding the sides of the magnet tt are berboard frames 66 and 57i which are held in position by lugs 68 that are formed integral with the cover and casing respectively and which have end portions that overlaps the fiberboard frames.

The permanent magnet 63 is intended for arc suppressing purposes as will be later described and the berboard frames 66 and el accommodate the are deposits which are formed by carbonizing which is an incident to the arc suppresw sion. At this point, it is well to note that the strength of the permanent magnet 63 is related to the magnitude of the arc which will be created by the break of the contacts. The magnitude of the are depends on the speed at which the contacts are broken and the strength of the current. There are now available permanent magnets having this required strength. Among such are the magnets sold under the trade name Alnico Extending downwardly from the top wall I I into the inner chamber is a projection 69 having an end face at 'It which is adapted to act as an abutment or stop as will be later described. This top wall I! is also the end walls of which are formed as the cylinformed with an opening at 'II,

accusa drical surfaces illustrated in the drawing. A manually operable lever 12 is formed with diametrically opposite projections 13 at each side thereof and these projections act as trunnions or pivots for mounting the lever 12. They are `received in recesses 'le formed in the .casing and cover, respectively, along the side edges of the opening li. This lever 'l2 carries an arcuate vWall structure i which is complementa'l to and snugly received within the curved end walls of the opening l i. This wall structure completely closes the opening and at the same time permits swinging of the lever 'l2 about the trun- -nions 13 as a pivotal mounting.

Extending inwardly into the inner chamber and carried by the lever 'i2 are a pair of legs 'l5 which are spaced apart with the lower free edge of .each leg formed with a notch 1l. The inner face of each leg t is aise formed with a V -shaped notch presenting inclined faces t and 'l that terminate at the lower edges of the leg. Thus the V-.shaped notches are wider than the notches il and the vfaces and l are adapted to function ,as stops in a manner now to be described.

A contact carrier It is of bifurcated construction defining a pair of legs 'I9 and 'which are integrally joined at the bottom and from each of which outstands a pin di that is received in the respective notch 1l. The lower end of this contact carrier 'E8 carries a contact 52. A ten- .sion coil spring 53 vhas its lower end anchored to the contact carrier 'E8 as represented at .84. The .otherend ci this spring dit is anchored to a rocker now to be described. It is evident that movement .of carrier i8 about pins 8l is limited by the stop faces 8 and l on the legs l.

A rocker t5 has trunnions se extending from `opposite sides thereof and these trunnions are journaled. in .the cover and casing respectively yas is brought out in Figure 5. The lower end of this rocker 85 carries a contact 8l which is comple- .mental to and adapted to engage the .contact 82. It is notable that the contact S2 is moved yaway .from the contact sl by a wiping action .caused :by the straightening of the lever l2 and carrier la. This rocher is made of a good ,conducting material such copper and its upper end is reduced in size to provide for the mounting of an insulating member im thereon. This insulating member may taire the form of a glass ring and it functions as an insulated anchorage for the upper end of the spring es. Mounted on opposite faces of the rocher 85 area pair of brackets 235i and 9&3, the connection being effected by spot or resistance welding; the hole shown at si in Figure 5 serving as a locating point. Each of these brackets 2S and Se is termed with a cam surface 3 which is adapted to cooperate with the respective side edge 92 of the leg it.

The rocker Se also carries an outwardly extending projection @t having a face at 95s that is adapted to engage abutment face lil. A flexible conductor 95 connects this projection 93 on the rocker e5 with the bimetal 46. Another flexible conductor St connects the contact carrier 18 with the terminal plate 23 passing through the opening 22 and being joined to the flange 24 in any preferred manner as by soldering.

The cover is shown at lll and is preferably made from an insulating material having transparent properties and which is susceptible of being tinted to a desired shade for the purpose of designating the capacity of the unit. It will be noted that the end wall 53, thickened wall structure l1, thickened wally structure I8, and

lprojection 45:9 are formed with openings, all of Operation `of the device ln outlining the operation of the above described .circuit breaker, attention is iirst called to Figure i which depicts the condition of the unit when the .circuit is closed. It will be noted that in this position the spring es being disposed at vone side of the pins 8i urges the contact B2 against .the contact lil because movement of the rocker is Vprevented .by the detent 5l which is in engagement .with the surface ed of the projection $3. In this position the upper end portion .or the carrier 'is is in substantial engagement with the stop face l. Under this condition, current will pass from the terminal plate 3| through the flange 35 thereof to the bimetal 46, conductor S5 connects the latter to the rocker dii. The current then passes from the rocker t5 through contacts 8T and 32 to contact carrier 'it and from there through the conductor et to the terminal plate 23.

Figure 2 depicts the unit in the condition in which the .circuit has been opened by manual operation of the lever l2. lt will be noted that the contacts 82 and 3'! have been moved apart with a wiping action to break the circuit. This has been achieved by movement of the contact 52 alone because the latch 5l still holds the rocker 8&5 .against movement. As the lever 'E2 is swung from the position shown in Figure l to that shown in Figure 2, the pivot point 8| passes from the left-hand side o fthe center line of the spring 53 (speaking with reference to the showing of the drawings) to the right-hand side. This causes the spring 83 to bias the contact 82 away from the contact el. It will be noted that this movement on the part of the lever l2 is accommodated because there is an appreciable space between the cam surfaces Q2 and Si. Thus, the lever may be moved without affecting the rocher .35. In this position the upper end of the carrier 'le engages the stop face E.

Figure 3 shows the condition of the unit which has been caused by circuit conditions to rupture the circuit by moving both the contacts t2 and 8l. The circuit .condition might either be an overload which aiects the birnetallic thermostat d so as to move the keeper piece 515 and latch Elfi carried thereby so that the detent 5l is withdrawn from the projection 23 or it may be a short circuit which will cause the rupture magnet i to have this effect on the latch member 55 which, it will be recalled, is also an armature for the magnet. Regardless of which may be the cause, when the detent 51 is withdrawn from the projection 93, the spring S3 being always under tension rotates the rocker t5 in a counterclockwise direction (speaking with reference to the showing of the drawings) and this movement is continued until the surface 9s engages the abutment surface 1D. As this movement takes place, the contact 3'! of course moves away from the contact 82. At the same time, the pivot pin 8l will be effected by the movement of the rocker arm to change its relative position with respect to the spring 83 and instead of being positioned on the left-hand side, as in the circuit closing position, its relative position is changed to the right-hand side and the contact 82 is also moved in the direction away from the contact 81.

As the contacts 82 and 81 move away from each other there ordinarily would be a tendency to arcing. However, this arcing is suppressed by the permanent magnet 63.

The position of the lever 'I2 after the circuit has been ruptured by circuit conditions is shown in Figure 3 which, it will be noted, is substantially intermediate the positions of Figures 1 and 2. In this position the cam surfaces 92 and 5 are in close proximity. Thus, when it is desired to reset the unit to close the circuit the lever 12 must iirst be swung in a counterclockwise direction to move the rocker 85 in a clockwise direc tion and again place the projection 93 under the retaining effect of the detent l of the latch 5B. The lever 'l2 may then be swung into the circuit closed position shown in Figure 1.

What is claimed is:

l. An electric circuit breaker comprising, bottom, side and top wall members providing a casing, a contact carrier and a rocker member pivotally mounted in casing and having respective contacts which. are cooperable with one another, the said contact carrier being manually operable for contact engagement and disengagement, and the saidv rocker being automatically operable in response to circuit overload conditions to disengage the contacts, and means for minimizing the adverse effects of arcing developeri upon engagement and disengagement of the said contacts, comprising, a shoulder on the bottom wall member of said casing, a permanent magnet mounted on the bottom Wall of said casing member, in endwise abutment with said shoulder', and having its midpoint approximately coinciding with the line at which the contacts engage one another, the said magnet extending along opposite sides of the respective paths of movement of the contact carrier and rocker when they are disengaged, the said permanent magnet being substantially wshaped in cross section and having sidewise portions residing closely adjacent the sidewise portions of said contacts when the latter are in engagement, whereby the magnetic eld of the permanent magnet cuts directly across the paths of movement of the said carrier and rocker contacts, the said casing side wall members having recesses therein engaging the external surfaces of said magnet sidewise portions.

2. An electric circuit breaker comprising, a casing having a contact carrier and a rocker member pivotally mounted therein, contacts mounted respectively upon said carrier and rocker, means for moving said carrier to contact engaging and disengaging positions manually, and means for moving said rocker to contact disengaging position automatically in response to circuit overload conditions, the said casing having a seat recess therein adjacent the point at which the contacts reside in engagement, a magnet member seated in said recess and secured thereby, the said magent member having portions respectively extending along the paths through which the contact carrier and rocker move to- Ward contact disengaging positions, the said magnet portions straddling the respective contacts of the carrier and rocker, whereby the magnetic eld of said magnet means is exerted directly across the paths of travel of the respective contacts in their movement toward and from engagement.

3. An electric circuit breaker comprising, a casing having a contact carrier and a rocker member pivotally mounted therein, contacts mounted respectively upon said carrier and rocker, means for moving said carrier to contact engaging and disengaging positions manually, and means for moving said rocker to contact disengaging position automatically in response to circuit overload conditions, the said casing comprising bottom and side Wall members configurated to provide a seat recess therein adjacent the point at which the contacts reside in engagement, a magnet member seated in said recess and secured thereby, the said magnet member having portions respectively extending along the paths lthrough which the contact carrier and rocker move toward contact disengaging positions, the said magnet portions stra'ddling the respective contacts of the carrier and rocker, whereby the magnetic field of said magnet means is exerted directly across the paths oi travel of the respective contacts in their movement toward and from engagement, the said casing also having shielding members residing yadjacent the side walls thereof above said magnet and beyond the endwise portions thereof.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,184,372 Von Hoorn Dec. 26, 1939 2,320,437 Jennings June l, 1943 2,367,382 Taylor Jan. 1G, 1945 2,426,880 Jackson et al. Sept. 2, 1947

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