US3268688A

US3268688A - Pushbutton-controlled overload circuit breaker

Info

Publication number: US3268688A
Application number: US390376A
Authority: US
Inventors: Ellenberger Jakob
Original assignee: Ellenberger and Poensgen GmbH
Current assignee: Ellenberger and Poensgen GmbH
Priority date: 1963-10-26
Filing date: 1964-08-18
Publication date: 1966-08-23
Anticipated expiration: 1983-08-23
Also published as: GB1046530A; DE1463114B2; AT258392B; DE1463114A1; SE301667B; CH424947A

Description

Aug. 23, 1966 J. ELLENBERGER 3, 8,6 8

PUSHBUTTON-CONTROLLED OVERLOAD CIRCUIT BREAKER Filed Aug. 18, 1964 2 Sheets-Sheet 1 27 26 Inventor. JHKOB ELLENBERGER by:

amt; W

Atiorney 5 Aug. 23, 1966 J. ELLENBERGER PUSHBUTTON-CONTROLLED OVERLOAD CIRCUIT BREAKER Filed Aug. 18, 1964 2 Sheets-Sheet 2 4/ 77 w l V 7 Inventor: JH/(OB E LLENBERGE R wwwf Mr/w Attorneys r: 3,268,688 Patented August 23, 1966 20 Claims. (31. 200-116) The present invention relates to a pushbutton-controlled overload circuit breaker which is provided with thermally responsive as well as trip-free releasing means and with a contact bridge which is pivotable and slidable on a control rod which is rigidly connected to the push button. When the circuit breaker is being switched off this contact bridge is pressed against an inclined surface and when the circuit breaker is being switched on, the contact bridge is taken along by the control rod by the engagement of a detent or projecting end on the contact bridge with a catch or shoulder on the control rod until one end of the contact bridge engages behind a holding detent on the thermally responsive releasing means.

There is an overload circuit breaker of the above-mentioned type already known which may be employed in place of one of the conventional safety fuses. This known circuit breaker may be produced in a simple manner and at a low cost and it operates reliably for a great length of time. However, this known overload circuit breaker has the disadvantage that it cannot be released by hand and that its switch positions cannot be indicated by signal circuits.

It is an object of the present invention to improve this known overload circuit breaker in a manner so as to permit the same to be switched off by hand and to indicate its switch positions by means of signal circuits. Another object of the invention is to design this overload circuit breaker so as to be of a simple construction, to be easily manufactured, assembled and installed, and to take up very little space.

According to the invention, these objects are attained by providing the control rod of the overload circuit breaker with a lever which has an inclined part on one end thereof and is pivotably mounted at its other end on the control rod. When the pushbutton is pulled out of the housing of the circuit breaker the inclined part of the lever slides along an abutment or edge whereby the lever is pivoted toward and pressed against the thermally responsive releasing means which are thereby bent until the holding detent thereof disengages from and releases the contact bridge. V

The pushbutton may therefore be employed for switching on as well as for switching off the circuit breaker according to the invention. Consequently, there is no need for a separate manual releasing element, and the size of the circuit breaker will therefore be reduced by the space which is usually required by such an additional releasing element.

In order to maintain the lever in a position in which the inclined part on one end thereof engages with the mentioned abutment, the opposite end of the lever is connected to a leaf spring so that the adjacent fiat surfaces of the lever and leaf spring normally lie flat on each other. The parallel outer edges of this leaf spring project laterally over those of the lever and are slidable in longitudinal grooves in the two opposite housing parts. The lever and the leaf spring are provided with corresponding apertures by means of which they are loosely fitted over a lateral projection on the free end of the control rod. The purpose of employing a leaf spring as a return spring for the lever is to save in space. The lever and the leaf spring may be produced in a simple manner by stamping operations in which a pair of small studs are also pressed out of the material of the lever which engage into corresponding apertures in the leaf spring and are riveted thereto. The lever and the leaf spring therefore form a single structural unit which during the assembly of the circuit breaker are simply fitted with their corresponding apertures over the lateral projection on the free end of the control rod.

For preventing any interference in the movement of the lever and the leaf spring with the contact bridge when the latter is in the connecting or on position, the central parts of the free ends of the lever and leaf spring are punched out so as to form a pair of arms on each of them. The ends of the two arms of the lever are bent at an inclined angle away from the leaf spring and form the inclined part previously referred to. When the contact bridge is in the on position, these inclined arms of the lever engage upon an edge of the contact bridge which then forms the mentioned abutment for the inclined part of the lever so that there is no need to provide any additional abutment. By the engagement of the inclined arms of the lever with the edge of the contact bridge the advantage is also attained that the contact pressure is increased between the contact bridge and the holding detent on the bimetal strip of the thermally responsive releasing means.

The end of the contact bridge which is most remote from the pushbutton is bent over at an angle so as to project and form an abutment which, in the off position of the circuit breaker, engages with a shoulder on the control rod so that, when the pushbutton with the control rod thereon is then depressed, this shoulder on the control rod acts upon the bent end of the contact bridge and takes the latter along until it engages behind the holding detent on the bimetal strip.

In order to simplify the production of the housing of the circuit breaker, this housing has an an inner recess into which a separate insert is fitted which is provided with an aperture through which the contol rod extends and with an inclined surface on which the contact bridge abuts when it is in the off position. This insert also serves as a bearing for guiding the control rod during its longitudinal movements.

An additional feature of the invention consists in providing on one-or both sides of the contact bridge a slide bar which preferably consists of insulating material and serves for the operation of signal contacts. Although both of these slide bars may either be employed for operating opening or closing contacts, it is of particular advantage to design one of these slide bars for the operation of opening contacts and the other for the operating of closing contacts. These slide bars may be guided in grooves in the side walls of the housing of the circuit breaker. In this manner the signal contacts will not be affected by jarring or vibrations since they are always held in their particular position without spring action.

For actuating the slide bars, the contact bridge may be provided with lateral studlike projections on which the slide bars are mounted with considerable play in the direction of movement of the control rod. This large play has the advantage that, when the circuit breaker is either switched on or off, the contact bridge may move for a certain distance without moving the slide bars. The kinetic energy of the contact bridge whichthen occurs produces a snap actuation of the signal contacts. From the fact that the slide bars are located directly on the contact bridge the advantage results that a perfect trip-free release is attained not only of the main contacts but also of the signal contacts of the circuit breaker.

In order to hold the slide bars safely on the studs of the contact bridge even in the off position of the contact bridge, the insert with the inclined surface is provided with side walls which extend in the direction of the control rod and cover the slide bars within the area in which they are mounted and secure them in their positions on the studs of the contact bridge. This also considerably facilitates the assembly of the circuit breaker. The pushbutton together with the control rod and the cont-act bridge together with the slide bars are first assembled so as to form a single structural unit which may subsequently be easily inserted into the housing during the final assembly of the circuit breaker. The side walls of the insert then hold the slide bars in their proper position on the contact bridge.

The terminal strips carrying the signal contacts may be secured in a simple manner by being inserted into suitable recesses in the two housing parts. They are then covered up by insulating plates so as to be insulated relative to the main circuit. For securing these insulating plates in their proper positions, an intermediate insulating member is placed between them which, in turn, is secured to the housing by a rivet which secures the two housing parts to each other.

Another feature of the invention consists in the fact that the spring which acts upon the contact bridge and serves for the trip-free release of the circuit breaker is supported on a fixed abutment which has an aperture through which the control rod extends and forms a separate element which is inserted into suitable recesses in the walls of the housing. This fixed abutment or insert insures that the cont-act bridge will be switched at a uniform speed to the off position when operated by hand or when a short circuit occurs. This is an advantage over the known overload circuit breaker as previouslyy referred to which does not react to a short circuit as quickly since by the pressure upon the pushbutton the force of the spring which is provided for the trip-free release is considerably reduced and this spring can therefore become active only with its residual spring pressure.

For the purpose of further simplifying the manufacture of the circuit breaker according to the invention, the upper end of the control rod is provided on opposite sides with recesses and this upper end is then inserted from one side into a corresponding recess in the lower end of the pushbutton. By fitting a sleeve tightly over the lower part of the pushbutton containing this recess, the pushbutton holds the upper end of the control rod securely with a viselike grip. According to a further feature of the invention, this sleeve which locks the pushbutton to the end of the control rod is provided with an inner annular recess into which the release spring is inserted, the other end of which is supported on the mentioned insert. This insert therefore saves a separate abutment for supporting the release spring.

The pushbutton and the locking sleeve are preferably made of different colors for the following purpose. When the circuit breaker according to the invention is switched on, only the pushbutton of one particular color projects from the housing. If, however, the circuit breaker is in its off position, not only the pushbutton but also the differently colored locking sleeve is visible above the housing. The two different switch positions of the circuit breaker can therefore be easily recognized by the single color of the pushbutton or the two colors of the pushbutton and the locking sleeve.

In order to be able to adjust the bimetal strip as simply and accurately as possible and so as to require the smallest possible space for these adjusting means one end of the bimetal strip is secured, preferably by welding, to one arm of an angular metal strip which is inserted into corresponding recesses in the two parts of the housing and the other arm of which is provided with a setscrew which engages upon the bimetal strip.

A further feature of the invention consists in the provision of very simple and effective means for mounting the circuit breaker in a fixed position on a control panel or the like. These means consist according to the invention of a small plate which is inserted between the two housing parts at the end thereof adjacent to the pushbutton and is further secured by a rivet which connects the two housing par-ts to each other. This small plate has a stud projecting from the housing at a certain distance from the threaded bushing on the end of the housing. When this threaded bushing is inserted into a bore in the control panel from the rear side thereof, this stud is also inserted into a corresponding recess or aperture in the panel adjacent to the mounting bore and it prevents the circuit breaker from turning when a lock nut is screwed upon the bushing and tightened against the front side of the panel.

The above-mentioned as well as numerous additional features and advantages of the present invention will become more clearly apparent from the following detailed description thereof which is to be read with reference to the accompanying drawings, in which FIGURE 1 shows an elevation of an overload circuit breaker according to the invention substantially in its natural size;

FIGURE 2 shows a view of the circuit breaker as seen from the left of FIGURE 1;

FIGURE 3 shows a top view of FIGURE 1;

FIGURE 4 shows an enlarged elevation view, partly in section, of the circuit breaker in the same position as shown in FIGURE 1 but without the upper part of the housing;

FIGURE 5 shows a view of the inside of the housing P FIGURE 6 shows a similar view of the other half of the housing which is omitted in FIGURE 4;

FIGURE 7 shows the circuit breaker according to FIG- URE 4 in the OE position;

FIGURE 8 shows the bimetallic strip with the fineadjustment device according to FIGURE 4;

*FIGURE 9 shows the upper part of the bimetallic strip, as seen in the direction of the arrow IX in FIG- URE 8;

FIGURE 10 shows the upper part of the bimetallic strip, as seen in the direction of the arrow X in FIG- UR-E 8;

FIGURE 11 shows a view of the lever and leaf spring unit as seen from the right of FIGURE 4;

FIGURE 12 shows a view of this unit, as seen from the left of FIGURE 11; while FIGURE 13 shows a view of the same unit as seen from the left of FIGURE 12.

As illustrated in the drawings, the overload circuit breaker according to the invention comprises a housing which consists of two

halves

1 and 2 which are molded of plastic and are connected to each other by tubular rivets 3. A pushbutton 4 projects from the upper end of the housing '1, 2, and is provided with a recess 5 in its lower end, as shown in FIGURE 4, into which the similarly shaped upper end of a control rod 6 is inserted in a direction at right angles to the central axis of the pushbutton 4. The lower end of the pushbott-on 4 is enclosed by a sleeve 7 which locks the upper end of the control rod 6 to the pushbutton 4. The lower part of sleeve 7 is provided with an inner annular recess 8 into which a release spring 9 is inserted, the lower end of which is supported on an insert 10 of insulating material. The pushbutton 4 and the locking sleeve 7 are differently colored-the pushbutton may, for example, be black and the sleeve white-for indicating whether the circuit breaker is in the on or off position. Thus, when the circuit breaker is switched on, only the black button projects from the housing, while when the circuit breaker is switched off, the white sleeve 7 also projects from the housing. The two

housing parts

1 and 2 further enclose the lower part of a threaded bushing .11 which has a square flange 12 on its lower end which is inserted into corresponding recesses 12 in the two

housing parts

1 and 2 and is thus nonrotatably secured therein. The

insert is also held in a fixed position in suitable recesses 10 in the two

housing parts

1 and 2.

The control rod 6 has a rectangular cross section and consists of solid insulating material. For guiding this control rod 6, the upper wall of the insert 10 is provided with an aperture into which the control rod is inserted. On its lower end the control rod 6 is provided with a lateral projection 13' which extends through corresponding openings in a lever 14 and a leaf spring 15 which are riveted together at their lower ends, as shown particularly in FIGURES 11 to 13. Lever 14 is for this purpose provided with a pair of studs 16 which are punched out of the material of the lever and extend through corresponding apertures 15 in the leaf spring 15 and are riveted to the latter. Along its

lateral edges

17 and 18, leaf spring 15 is guided in grooves 19 in both

housing parts

1 and 2 so as to be slidable in the longitudinal direction. The upper parts of lever 14 and leaf spring 15 are bifurcated by the provision of central recesses. The two arms 20 of lever 14 which are thus formed are bent at their upper ends at 21 at an oblique angle away from the leaf spring 15. These bent ends 21 engage upon the edges 22 of the right end portions of a contact bridge 23 which is pivotably and slidably mounted on the control rod 6. In FIGURE 4, the contract bridge 23 is shown in its connecting or on position, whilein FIGURE 7 it is shown in its disconnecting or ofi position. In its on position according to FIGURE 4, the right end of the angular contact bridge 23, which is produced by a stamping operation, is held in engagement with a holding detent 24 on a bimetal strip 25.

This bimetal strip 25 is welded together with one arm 26 of an angular metal strip 27 which is inserted into suitable slots in the two

housing parts

1 and 2 and thus held in a fixed position. The other arm 28 of strip 27 carries a setscrew 29 which engages upon the bimetal strip 25. Thus, when the setscrew is screwed further into the arm 28, the bimetal strip 25 is pivoted toward the right so that its holding detent 24 is moved further away from the right end of the contact bridge 23. The bimetal strip '25 carries a heating coil 30 which is insulated therefrom and connected at one end to a terminal strip 31 which is provided with a connecting screw 32.

As illustrated particularly in FIGURES 9 and 10, the upper end of the bimetal strip 25 has an aperture 33 into which a small copper plate is inserted which forms the holding detent 24. At one side of the bimetal strip 25 this copper plate has a bore into which the upper end 30" of the heating coil 30 is inserted and riveted. At the other side of the bimetal strip 25, the copper plate 24 has lateral shoulders which support it on the bimetal strip. In order to prevent the copper plate 33 from being bent upwardly, a small bracket 34 is stamped out of the bimetal strip 25 and bent so as to abut with its lower edge 35 against the upper side of the copper plate 24, as shown particularly in FIGURE 8.

The vertical arm 23' of contact bridge 23 cooperates with a fixed contact 36 on a terminal strip 37 which is likewise provide with a connecting screw 32. The main circuit therefore extends from the terminal strip 31 via the heating coil 30, the contact bridge 23, and the contact 36 to the. terminal strip 37.

As shown particularly in FIGURE 7, the contact bridge 23 is acted upon by a spring 38 which serves for the trip-free release of the circuit breaker and the lower end of which is supported on a stationary abutment 39 which is inserted into suitable slots 39' in the two

housing parts

1 and 2. In order to prevent it from being bent, the angular part of contact bridge 23 is provided with a reinforcing corrugation 55 which is produced by stamping.

Contact bridge 23 is provided on both sides with small studlike projections 40 which serve as means for connecting the contact bridge to a pair of slide bars 41 and 42. Both of these slide bars 41 and 42 are provided at their upper ends with square holes 43 into which the studlike projections 40 engage with considerable play which permits the slide bars to slide vertically on and relative to these projections 40. Slide bar 41 is adapted to act upon a contact spring 44 which cooperates with another contact 45, while the slide bar 42 is adapted to act upon a contact spring 46 which cooperates with another contact 47. These contacts 44 to 47 serve as signal contacts. They are covered up by insulating plates 56 which are inserted into the two

housing parts

1 and 2 and are held in a fixed position by a spacing member 57 of insulating material which is likewise inserted between the two

housing parts

1 and 2. The insulating plates 56 and the spacing member 57 are provided with bores 58 which are in alignment with each other and are adapted to receive a tubular rivet 3 for securing the two

housing parts

1 and 2 to each other after the various elements are installed therein. The opposite sides of the spacing member 57 are provided with studlike projections which engage into apertures 59 in the insulating plates 56 and prevent the spacing member 57 from turning. The ends of the signal contacts 44 to 47 which project from the housing may be connected to suitable signal circuits for indicating the particular switch position in which the circuit breaker is set at any time. Slide bar 41 serves for opening the

contacts

44 and 45, while slide bar 42 serves for closing the

contacts

46 and 47 when the contact bridge 23 is moved to its on position as shown in FIGURE 4. Both contact springs 44 and 46 have the tendency to engage under initial tension against their associated contacts and 47.

For mounting the overload circuit breaker on a control I panel or the like the threaded bushing 11 is provided with a buckled washer 48 and a nut 49. In order to prevent the circuit breaker from turning when it is being mounted on this panel and when for this purpose the nut 49 is being tightened, a small metal plate 50 is inserted between the two

housing parts

1 and 2 and held in a fixed position therein by a tubular rivet 3 which passes through the housing parts and this metal plate. This metal plate 50 has a studlike projection 51 which engages from the rear into a corresponding bore or recess in the control panel when the circuit breaker is secured thereto.

When an excess current occurs, the bimetal strip 25 is heated by the heating oil 30 and bent so far in the clockwise direction from the position as shown in FIGURE 4 that its holding detent 24 disengages from the contact bridge 23 and allows the latter, under the action of the re lease spring 9 to be pressed against the inclined surface 52 of the insert 10, as illustrated in FIGURE 7. The lower, inwardly projecting end 53 of contact bridge 23 then engages with a shouder 54 on the control rod 6 so that, when the circuit breaker is being switched on the control rod 6 takes along the contact bridge 23 until its right end has passed over and snapped behind the holding detent 24 on the bimetal strip 25. When the operator of the circuit breaker then takes his finger oh the pushbutton 4, the contact bridge 23 is suddenly pivoted by the spring 38 in the clockwise direction, whereby the vertical arm 23 of the contact bridge is moved into engagement with the fixed contact 36 so that the main circuit is closed. At the same time, the signal contacts 44 to 47 are also actuated by the slide bars 41 and 42.

If the circuit breaker is to be switched off by hand, the pushbutton 4 is pulled out of the

housing

1, 2. The inclined ends 21 of the lever 14 then slide along the edges 22 of contact bridge 23, whereby the lever 14 is pivoted in the clockwise direction from the position as shown in FIGURE 4 and is thereby pressed against the bimetal strip 25 which is then bent until its holding detent 24 is released from the end of the contact bridge 23 permitting the latter under the action of the release spring 9 to pivot to the off position, as shown in FIGURE 7, in which the contact bridge 23 engages upon the inclined surface 52 of the insert 10. Simultaneously with the movement of the contact bridge 23 the connecting

bars

41 and 42 are also moved abruptly so that the signal contacts 44 to 47 are likewise opened and closed instantaneously.

Although my invention has been illustrated and described with reference to the preferred embodiment thereof, I wish to have it understood that it is in no way limited to the details of such embodiment, but is capable of numerous modifications within the scope of the appended claims.

Having thus fully disclosed my invention, what I claim 1s:

1. A pushbutton-controlled overload circuit breaker having thermally responsive releasing means with a holding detent thereon, and trip-free releasing means, a housing, a pushbutton guided in and projecting from said housing, a control rod rigidly connected to said pushbutton, a contact bridge pivotable and slidable on said control rod within said housing, an inclined surface in said housing, said contact bridge being pressed aganst said inclined surface when the circuit breaker is switched off, said contact bridge having a projection and said control rod having a shoulder associated with said projection, said contact bridge being taken along by said control rod when the circuit breaker is being switched on by the engagement of said projection with said shoulder until one end of said contact bridge engages behind and is arrested by said holding detent of said thermally responsive releasing means, a lever having an inclined part at one end and pivotably mounted at the other end on said control rod, and means forming an edge in said housing associated with said lever so that, when said pushbutton is pulled out of said housing, said inclined part of said lever slides along said edge, whereby said lever is pivoted toward and pressed against said thermally responsive releasing means which are thereby bent until said holding detent thereof disengages from and releases said contact bridge.

2. An overload circuit breaker as defined in claim 1, further comprising a leaf spring superimposed upon said lever and connected thereto at the end thereof opposite to said inclined end, said leaf spring having parallel lateral edges projecting over said lever and slidably guided in longitudinal grooves in two opposite walls of said housing, said control rod having a lateral projections on the free end thereof, said lever and said leaf spring having corresponding apertures and loosely fitted by means of said aperture over said lateral projection on said control rod.

3. An overload circuit breaker as defined in claim 2, in which said lever and said leaf spring are stamped parts, said lever having pressed-out studs and said leaf spring having apertures corresponding to said studs, said studs engaging through said apertures in said leaf spring and being riveted thereto.

4. An overload circuit breaker as defined in claim 3, in which the free ends of said lever and said leaf spring are bifurcated so that each of them has two arms, the two arms of said lever being bent at an oblique angle away from said leaf spring to form said inclined part, and engaging upon an edge of said contact bridge when the latter is in the on position.

5. An overload circuit breaker as defined in claim 1, in which said control rod has a lateral projection on its free end forming said shoulder, the end of said contact bridge most remote from said pushbutton being bent over at an angle to form said first mentioned projection and, in the off position of said contact bridge, engaging with said projection on said control rod so as to be taken along by the latter when said pushbutton is depressed.

6. An overload circuit breaker as defined in claim 1, further comprising a separate insert member comprising said inclined surface, said insert member having an aperture through which said control rod extends, said housing having an inner recess in at least one of its opposite walls into which said insert member is fitted so as to be rigidly secured thereto.

7. An overload circuit breaker as defined in claim 1,

8 further comprising signal contacts, and a slide'bar pref er-ably consisting of insulating material on at least one side of and connected to said contact bridge for actuating said signal contacts.

8. An overload circuit breaker as defined in claim 1, further comprising opening and closing signal contacts, and slide bars on opposite sides of and connected .to said contact bridge, one of said slide bars adapted to actuate said opening contacts and the other slide bar adapted to actuate said closingcontacts.

9. An overload circuit breaker as defined in claim 8, in which the inner sides of the side walls of said housing have grooves, said slide bars being guided in said grooves.

10. An overload circuit breaker as defined in claim 7, in which said contact bridge has a stud on at least one side thereof, said slide bar having an aperture therein, said stud engaging into said aperture with considerable play in the direction of movement of said control rod.

11. An overload circuit breaker as defined in claim 10, further comprising a separate insert member comprising said inclined surface and having an aperture through which said control rod extends, and means for holding said slide bar on said stud of said contact bridge when said contact bridge is in the ofi. position.

12. An overload circiut breaker as defined in claim 11, in which said means comprise a side wall of said insert member extending in the direction of said control rod and covering said aperture of said slide bar when said contact bridge is in the otf position.

13. An overload circuit breaker as defined in claim 7, further comprising supports carrying said signal contacts and secured in recesses provided in at least one wall of said housing, and at least one insulating plate covering said supports.

14. An overload circuit breaker as defined in claim 8, in which said housing consists of two separate parts, and further comprising supports carrying said signal contacts and secured in recesses provided in the opposite walls of said two housing parts, insulating plates covering said supports, an insulating member inserted between said insulating plates for maintaining the latter in a fixed position in said housing, said insulating member having an aperture, and a rivet extending through said aperture in said insulating member and through corresponding apertures in said two housing parts for securing said insulating member and said two housing parts to each other.

15. An overload circuit breaker as defined in claim 1, further comprising a fixed abutment member mounted in recesses in the opposite walls of said housing and having an aperture, said control rod extending through said aperture, said trip-free releasing means comprising a coil spring on said control rod and having one end acting upon said contact bridge and the other end supported on said fixed abutment member.

16. An overload circuit breaker as defined in claim 1, in which the end of said control rod which is connected to said pushbutton is provided on opposite sides with recesses, the lower part of said pushbutton having a recess of a shape corresponding to that of said recessed end of said control rod, said end of said control rod being inserted into said recess in said pushbutton in a direction at right angles to the central axis of said pushbutton, and a sleeve fitted over and enclosing the lower part of said pushbutton and locking said end of said control rod and said pushbutton to each other.

17. An overload circuit breaker as defined in claim 16, in which said locking sleeve has an inner annular recess, and a release spring inserted into and acting with one end upon the bottom of said annular recess and thus upon said pushbutton, the other end of said release spring being supported on said insert.

18. An overload circuit breaker as defined in claim 16, in which said pushbutton and said locking sleeve are differently colored.

19. An overload circuit breaker as defined in claim 1,

in which said thermally responsive releasing means comprise a bimetal strip, said holding detent being secured to said bimetal strip near one end thereof, an angular metal strip mounted in corresponding recesses in the opposite walls of said housing and having one arm rigidly secured to the other end of said bimetal strip and supporting said bimetal strip, and a setscrew screwed into the other arm of said angular strip and adapted to engage upon said bimetal strip for adjusting the same.

20. An overload circuit breaker as defined in claim 1, in which said housing consists of two separate parts having corresponding apertures, and further comprising a small plate having an aperture inserted between said two housing parts at the end thereof adjacent to said push- 10 said plate and said housing parts for securing said plate and said housing parts to each other, said plate having a stud projecting from said housing at a certain distance from said pushbutton, said stud being adapted to engage into a control panel or the like so as to prevent said circuit breaker from turning when mounted on said panel.

References Cited by the Examiner UNITED. STATES PATENTS 10 2,816,192 12/1957 Ingwersen 200116 2,895,028 7/ 1959 Ellenberger 20088 2,952,757 9/1960 Ellenberger 2001 16 3,031,542 4/ 1962 Ellenberger 2001 16 button, and a rivet extending through said apertures in 15 BERNARD A. GILHEANY, Primary Examiner.

Claims

1. A PUSHBUTTON-CONTROLLED OVERLOAD CIRCUIT BREAKER HAVING THERMALLY RESPONSIVE RELEASING MEANS WITH A HOLDING DETENT THEREON, A TRIP-FREE RELEASING MEANS, A HOUSING, A PUSHBUTTON GUIDED IN AND PROJECTING FROM SAID HOUSING, A CONTROL ROD RIGIDLY CONNECTED TO SAID PUSHBUTTON, A CONTACT BRIDGE PIVOTABLE AND SLIDABLE ON SAID CONTROL ROD WITHIN SAID HOUSING, AN INCLINED SURFACE IN SAID HOUSING, SAID CONTACT BRIDGE BEING PRESSED AGAINST SAID INCLINED SURFACE WHEN THE CIRCUIT BREAKER IS SWITCHED OFF, SAID CONTACT BRIDGE HAVING A PROJECTION AND SAID CONTROL ROD HAVING A SHOULDER ASSOCIATED WITH SAID PROJECTION, SAID CONTACT BRIDGE BEING TAKEN ALONG BY SAID CONTROL ROD WHEN THE CIRCUIT BREAKER IS BEING SWITCHED ON BY THE ENGAGEMENT OF SAID PROJECTION WITH SAID SHOULDER UNTIL ONE END OF SAID CONTACT BRIDGE ENGAGES BEHIND AND IS ARRESTED BY SAID HOLDING DETENT OF SAID THERMALLY RESPONSIVE RELEASING MEANS, A LEVER HAVING AN INCLINED PART AT ONE END AND PIVOTABLY MOUNTED AT THE OTHER END ON SAID CONTROL ROD, AND MEANS FORMING AN EDGE IN SAID HOUSING ASSOCIATED WITH SAID LEVER SO THAT, WHEN SAID PUSHBUTTON IS PULLED OUT OF SAID HOUSING, SAID INCLINED PART OF SAID LEVER SLIDES ALONG SAID EDGE, WHEREBY SAID LEVER IS PIVOTED TOWARD AND PRESSED AGAINST SAID THERMALLY RESPONSIVE RELEASING MEANS WHICH ARE THEREBY BENT UNTIL SAID HOLDING DETENT THEREOF DISENGAGES FROM AND RELEASES SAID CONTACT BRIDGE.