US3319035A - Circuit breaker with sealing means for handle opening - Google Patents

Description

M 9 1957- F. L. GELZHEISEIR 3,319,035

CIRCUIT BREAKER WITH SEALING MEANS FOR HANDLE OPENING Filed March 4, 1966 "OFF" 97 "2 a vfas FIG.4.

I r 422 I (-x/ H INVENTOR- A Francis L. Gelzheiser m 424 432 Maw/Mk ATTORNEY United States Patent 3,319,035 CIRCUIT BREAKER WITH SEALING MEANS FOR HANDLE OPENING Francis L. Gelzheiser, Fairfield, Conn., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Mar. 4, 1966, Ser. No. 531,966 9 Claims. (Cl. 200-168) This invention relates to circuit breakers of the molded case type and more particularly to means for sealing the handle opening in such circuit breakers.

In a conventional circuit breaker of the molded case type, an electrically insulating housing is provided with an opening through which an operating handle extends to permit manual opening and closing of the circuit breaker. In order to substantially close off the opening in the housing in the different operating positions of the breaker handle, a shielding member or plate is normally provided which is slidably movable with respect to the housing and which maybe formed integrally or secured to the associated handle. It has been found necessary in the past to provide certain mechanical clearances between the handle structure of the breaker and its associated housing in order to permit movement of the handle to its different operating positions. When such clearances are provided, a problem may arise when a circuit breaker is called upon to interrupt an arc during certain overload conditions since hot gases may be generated under pressure and escape from the housing around the operating handle through Whatever clearances are provided. The escape of such hot gases under pressure may either cause injury to personnel or may start a fire during certain standard tests which are conducted on circuit breakers of the molded case type. Various means have been proposed in the pastto overcome this problem, but it has been found that such means are either unduly complicated in structure or olfer only a limited degree of improvement. It is therefore desirable to provide an improved means for preventing hot arc gases under pressure from escaping around the operating handle of a circuit breaker of the molded case type.

It is an object of this invention to provide a new and improved circuit breaker having a housing formed from electrically insulating material.

Another object of this invention is to provide an improved means for preventing hot arc gases from escaping around the operating handle of a molded case circuit breaker.

Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description, taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a side elevational view of a circuit breaker embodying the principal features of the invention with part of the housing broken away;

FIG. 2 is a partial, sectional end view of the circuit breaker shown in FIG. 1 illustrating the handle structure of the circuit breaker;

FIG. 3 is an enlarged isometric view of a modified circuit breaker illustrating a second embodiment of the invention;

FIG. 4 is an enlarged, partial, sectional end view of the circuit breaker handle structure shown in FIG. 3;

FIG. 5 is an enlarged, partial, sectional end view of a circuit breaker handle structure illustrating a third embodiment of the invention; and

FIG. 6 is an enlarged, isometric view of a portion of a circuit breaker illustrating a fourth embodiment of the invention.

3,319,035 Patented May 9, 1967 Referring now to the drawings and FIG. 1 in particular, there is illustrated a circuit breaker 3 of the molded case type, such as described in greater detail in US. Patent No. 2,568,423, issued to E. J. Walker et al. and assigned to the same assignee as the present application. The circuit breaker 3 comprises a housing member or base 11 and a cover member or plate 13 which are both formed or molded from an electrically insulating material. The cover member 13 cooperates or forms with the housing base 11, a compartment in which the circuit breaker mechanism 14- is disposed. The mechanism 14 includes a stationary contact 15, a movable contact 17, an operating mechanism 19 and a tripping device 21.

The stationary contact 15 is rigidly secured to the inner end of an electrical conductor or terminal 23 that extends out of the compartment formed by the housing 11 and its associated cover 13. The outer end of the terminal 23 is provided with a connecting means 27 for connecting the terminal 23 in an electric circuit. At the opposite end of the housing 11 is a terminal 29 which, at its inner end, supports the trip device 21 and which is provided with a connector 31 at its outer end for connecting the terminal 29 in an electric circuit.

The movable contact 17 is rigidly or fixedly secured on the free end of a U-shaped switch or contact arm 37. The opposite legs of the U-shaped contact arm 37 are supported in recesses in the legs 45 of an operating member 35 which is pivotally supported by means of the trunnions 37 at the opposite sides thereof. The trunnions 37 are rotatably mounted in bearing supports which are formed or molded integrally in the housing 11 and its associated cover 13. An overcenter operating spring 39 is supported under tension between the bight portion of the contact arm 37 and a releasable trip member 41 that is pivotally supported on a pin 4-3 which, in turn, is supported in associated openings in the housing 11 and its associated cover 13. The releasable trip member 41 is latched at its free end by means of the trip device 21.

The operating member or lever 35 is formed or molded from an electrically insulating material and is provided with an operating handle 49 which, in this instance, is molded integrally therewith and which extends through an opening 47 in the housing 11. The operating member 35 is also provided with an arcuate member or shield 112 which is molded integrally therewith or secured thereto. The arcuate member 112 cooperates with the arcuate inner surfaces 103 and and the substantially flat surfaces 101 of the housing 11 and its associated cover around the opening 47 to substantially close the opening 47 in any position of the handle 49. The operating member 35 is also formed with opposite stop surfaces 51 which cooperate with corresponding internal surfaces 53 provided on the housing 11 and its associated cover to limit the operating movement of the operating member 35 in both directions.

It should be noted that the contact arm 37 is electrically connected to one end of a tripping bimetal 57, which forms part of the trip device 21, by means of a flexible conductor 59. The other end of the tripping bimetal is fixedly secured to the terminal 29 by means with a suitable fastening member, such as the screw 61. When the circuit breaker 3 is in a closed circuit condition, as shown in FIG. 1, the electric circuit through the breaker 3 extends from the terminal 23 through the separable contacts 15, 17, the contact arm 37, the flexible conductor 59, and the current carrying tripping bimetal 57 to the terminal 29.

The circuit breaker 3 may be manually operated by actuation of the operating member 35. Clockwise movement of the handle 49 from the position shown in FIG. 1 actuates the operating member 35 to move the legs of the contact arm 37 overcenter to the left of the line of action of the overcenter operating spring 39 whereupon the )perating spring 39 biases or actuates the contact arm 37 oward the open position and causes movement of the conact arm 37 to the open position with a snap action. The :ontact arm 37 therefore moves in a counterclockwise diection about the upper pivot supports in the operating nember 35 until the contact arm 37 has stopped in the open or off position when the contact arm 37 engages 1 projection 63 that is molded integrally with the housing 11. When the contacts 15, 17 are in the open position, he contacts 15, 17 may be manually closed by counter- :lockwise movement of the handle 49 from the ofl posi- Lion which moves the operating member 35 to actuate the legs of the contact arm 37 overcenter to the right of the line of action of the overcenter spring 39 whereupon the spring 39 moves the contact arm 37 from the open or off position to the closed position shown in PEG. 1 with a snap action.

The circuit breaker 3 is designed to be tripped open instantaneously in response to overload currents above a predetermined value and to be tripped open after a time delay in response to lesser overload currents below the predetermined value by means of the trip device 21. In addition to the tripping bimetal 57 previously mentioned, the trip device 21 includes a latching bimetal 65 that latches the free end of the trip member 41 and also compensates the operation of the circuit breaker 3 for changes in the ambient temperature. The latching bimetal 65 is welded or otherwise secured at the upper end thereof to the upper end of the tripping 'bimetal 57. A magnet member 67 is rigidly mounted on and surrounds three sides of the tripping bimetal 57. The magnet member 69 is rigidly secured to one side of the latching bimetal 65 by means of a suitable rivet that also secures a latch 71 to the opposite side of the latching bimetal 65. As shown in FIG. 1, the latch 71 normally engages the free end of the trip member 41 to prevent clockwise rotation of the trip member 41 about the pivot pin 43.

Upon the occurrence of an overload current above the normal rated current of the circuit breaker 3 but below a predetermined value, the tripping bimetal 57 is heated by the current flow therethrough and it deflects, moving its free end toward the right, as viewed in PEG. 1, during which movement it engages an insulating button 73 which is mounted at the free end of the latching bimetal 65 to thereby move the latching bimetal 65 in the same direction causing the latch 71 to move correspondingly and release the trip member 41. The trip member 41 is then rotated by the force of the spring 39 in a clockwise direction about the pivot pin 43. As the trip member 41 rotates about the pivot pin 43, the line of action of the spring 39 is moved to the right of the upper end of the switch arm or contact arm 37 whereupon the spring 39 contracts to move the contact arm 37 to the open position. The trip mem ber 11 is stopped in the lower position when it engages the upper side of the projection 63 on the housing 11. During the tripping operation, the handle 49 is automatically moved to an intermediate position between the on and off positions in a well known manner. The circuit breaker 3 is trip-free in that the contact arm 37 will be actuated to the tripped or open position upon the release of the tripping member 41 even if the handle 49 is held in the on position.

Before the contacts 15, 17 can be closed following an automatic tripping operation, it is necessary to reset and relatch the operating mechanism of the circuit breaker 3. This is accomplished by moving the handle 49 in a clockwise direction, as viewed in FIG. 1, to the full off position during which movement of a leg 45 of the operating member 35 engages a pin 75 to actuate or move the releasable member 41 in a counter clockwise direction about the pivot pin 43. Near the end of this movement, the free end of the tripping member 41 wipes by the lat-ch 71 slightly flexing the latching bimetal 65. When the free end of the tripping member 41 is past the latch 71, the latching bimetal 65 snaps back to latch the tripping member 41 in the latched position shown in FIG. 1. Thereafter, the circuit breaker 3 can be manually or automatically operated in the manner hereinbefore described.

Upon the occurrence of an overload current above the predetermined value, the current flowing through the tripping bimetal 57 sufliciently energizes the magnet member 67 to attract the magnet member 69 whereupon the magnet 69 is instantaneously drawn toward the magnet 67 thereby flexing the latching bimetal toward the right, as viewed in FIG. 1, to release the tripping member 41 and eflect a tripping operation of the circuit breaker 3 in the same manner previously described.

When the contacts 15, 17 open, an arc is established between the movable contact 17 and the stationary contact 15. This are is extinguished by means of the arc-extinguishing structure 13 which in this case comprises two insulating side plates 137 (only one shown) and a plurality of magnetic arc-extinguishing members or plates 139 which are disposed between the side plates 137. The plates 139 are generally U-shaped and the arc is attracted into the plates 139 to be broken up into a plurality of serially related arcs, which arcs are rapidly extinguished in a manner well known in the art. The arc during circuit interruption may generate hot gases which expand creating pressure that forces the gases out of the compartment formed by the housing 11 and its associated cover.

When the circuit breaker 3 interrupts an overload or short circuit current, these gases are forced out under very high pressures. During the interruption of these overload or short circuit currents, it is also possible that particles of metal from the contacts 15, 17 or the arc-extinguishing plates 139 will be forced out of the circuit breaker housing 11. These hot arc gases and, in some instances, hot metallic particles are forced out through a vent passage 141 at the left end of the circuit breaker 3, as viewed in FIG. 1.

In order to prevent such hot arc gases and hot metallic particles from escaping around the handle 49 and the arcuate member 112 of the operating member 35, the arcuate member 112 is provided with a relatively thin, resilient fin which is preferably formed integrally or molded around the periphery of the upper surface of the arcuate member 112, as shown in FIGS. 1 and 2. The fin 116 projects laterally from the sides of the arcuate member 112 to bear against the substantially flat walls 101 of the housing 11 and its associated cover and projects from the opposite ends of the arcuate member 112 to bear against the adjacent arcuate inner surfaces 103 and 105 of the housing 11 and its associated cover to seal off any clearances which might otherwise be present between the operating member 35 and the opening 47 in the housing 11 and its cover. The arcuate member 112 and the associated fin are preferably formed from an electrically insulating material of the thermoplastic type having a high lubricity or low coeflicient of friction to facilitate the sliding movement of the operating member 35 with respect to the associated housing 11 and its cover. Suitable thermoplastic materials would include thermoplastic polyamide materials, such as that sold under the trademark "nylon, high molecular weight *polyoxymethylene material, such as that sold under the trademark Delrin or fluorocarbon polymer materials, such as polytetrafluoroethylene material of the type sold under the trademark Teflon. It is important to note that the fin 110 may be readily designed to be held in a predominantly compressive stressed condition when the operating member 35 is assembled inside the housing 11 and its associated cover in order to maintain the fin 110 in bearing relation with the inner surfaces of the housing 11 and its associated cover around the entire periphery of the arcuate member 112 in all operating positions of the handle 49. The fin 110 therefore would eliminate the need for a separate spring to bias the arcuate member 112 against the adjacent surfaces of the housing 11 and its associated cover around the opening 47. It is to be understood that in certain applications, the fin 110 may be formed integrally with the adjacent inner surfaces of the housing 11 and its associated cover to bear against the arcuate member 112 of the operating member 35 to similarly seal the clearances that would otherwise exist "between the operating member 35 and the housing 11. It is to be noted that certain variations in the dimensions of the parts which make up the circuit breaker 3 will be taken up by the resilience of the fin 110.

Referring now to FIGS. 3 and 4, a modification of the invention is illustrated which is incorporated in a circuit breaker 30 of the molded case type which in general is similar to the circuit breaker 3 previously described. The circuit breaker 30 is specifically of the type which is described in greater detail in US. Patent 3,211,877 which issued October 12, 1965, to E. J. Walker et al. and which is assigned to the same assignee as the present application. Similarly to the circuit breaker 3, the circuit breaker 30 includes a housing 211 formed or molded of electrically insulating material and a handle structure or operating member 250 including a handle portion 249 which projects or extends from inside the housing 211 through an opening 247 which is provided in the housing 211. The operating member 250 includes a generally arcuate plate or shield member 212 which may be formed integrally with or secured to the handle portion 249 and is also formed or molded of an electrically insulating material of the types previously mentioned. It is to be noted that the size of the cross section of the opening 247 in the housing 211 is smaller than the area of the upper surface of the arcuate member 212 and that the adjacent walls of the housing 211 generally overlap the upper surface of the arcuate member 212, as indicated in FIG. 4. In order to prevent the escape of hot arc gases around the operating member 250 which might otherwise escape through the clearances between the operating member 250 and the housing 211, a relatively thin, resilient fin 210 is preferably molded or formed integrally around the periphery of the upper surface of the arcuate member 212 to project generally upwardly away from the upper surface toward the inner surface of the housing 211, as indicated at 203 in FIG. 4, which is also formed to be generally arcuate, similarly to the arcuate member 212. The fin 210 bears against the inner surface of the associated housing 211 around substantially the entire periphery of the arcuate member 212 in all positions of the operating member 250 which is actuated to open and close the circuit breaker 30, as explained in detail in the patent mentioned above. In order to bias the operating member 250 toward the hous ing 211 and to maintain the fin 210 in a predominantly compressive stressed condition, and to thereby seal any opening or clearance which might otherwise exist between the operating member 250 and the housing 211, a separate spring may be disposed inside the handle portion 249, as shown in detail in the patent just mentioned. The material from which the arcuate member 212 and the associated fin 210 is formed is preferably one of those previously described in detail having a relatively high lubricity or relatively low coeflicient of friction to facilitate the movement of the operating member 250 with respect to the associated housing 211.

Referring now to FIG. 5, there is illustrated another modified form of the invention in a circuit breaker 300 which is similar to the circuit breaker 30 except as to the configuration of the fin 310 which is provided on the operating member 350. The circuit breaker 300 includes an insulating housing 311 having an opening 347 therein through which projects the handle portion 349 of the operating member 350 which also includes an arcuate member 312 that is either formed integrally with or secured to the handle portion 249. In general, the circuit breaker 300 is similar to the circuit breaker 30 just described except that the relatively thin, resilient fin 310 which is preferably formed integrally around the periphery of the upper surface of the arcuate member 312 is generally V-shaped in cross section, as shown in FIG. 5. The relatively thin fin 310 need not be held in a stressed condition against the inner surface of the associated housing 311 around the opening 347 during normal operating conditions of the circuit breaker 300, but when a heavy fault or short circuit condition occurs, and relative hot arc gases under pressure are generated, the resulting gas pressure will force the fin 310 into sealing engagement with the adjacent internal arcuate surface of the housing 311 to prevent hot arc gases or other particles from escaping through the opening 347 around the operating member 350.

In applications where it is not convenient to form a relatively thin fin as previously disclosed on either the operating member or the associated housing, the modified construction shown in FIG. 6 may be employed in a circuit breaker which would be similar to the circuit breaker 30 previously described, except that the relatively thin fin 210 on the operating member 250 will be omitted in the modified construction. As shown in FIG. 6, the insulating housing 411 of the circuit breaker would include, as illustrated, a generally rectangular opening 432 in which is disposed a generally hollow cylindrical or tubular insert member 400 which includes a central opening 447 and which is preferably formed or molded from one of the electrically insulating materials previously mentioned having a relatively high lubricity or a relatively low coefficient of friction. The insert member 400 includes a tapered flange portion 422 at the upper end with the sides of the insert member 400 at the lower end being generally arcuate in configuration, as indicated at 424. The insert member 400 also includes a relatively thin resilient fin 410 which is preferably formed integrally therewith at the lower end around the periphery of the insert member 400 to bear against the upper surface of an -op erating member, such as the operating member 250 which would not require a relatively thin fin on its upper surface in the construction shown in FIG. 6. The tapered flange 422 at the-upper end of the insert member 400 would permit assembly of the insert member 400 through the opening 432 of the housing member 411 until the tapered flange portion 422 snapped over the outer surface of the housing member 411 around the opening 432. The relatively thin fin 410 would bear against the housing member 411 at the lower edge or inner surface of the housing member 411 around the opening 432 and project generally downward, as viewed in FIG. 6, toward the associated operating member to be held in a predominantly compressive stressed condition to thereby substantially seal off any clearances or openings that might otherwise exist between the associated operating member (not shown) and the insert member 400. It is to be noted that the snap fit of the insert member with respect to the housing member 411 would substantially prevent the escape of any hot arc gases between the insert member 400 and the opening 432 in the housing member 411. It is also to be noted that in the modified construction shown in FIG. 6, the insert member 400 would be disposed between the opening 432 and the housing member 411 and the associated operating member to prevent the escape of hot arc gases through the opening 447 in the insert member 400.

The apparatus embodying the teachings of this invention has several advantages. For example, an improved means is disclosed for preventing the escape of hot arc gases around the operating member of a molded case circuit breaker which eliminates the need for a number of additional parts which may be relatively complicated in structure and which also permits certain variations in the dimensions of the assembled parts of the circuit breaker as disclosed. In addition, the relatively thin fin provided in the different embodiments of the invention may be formed from a material having a high lubricity to facilitate the movement of the operating member with respect a the associated insulating housing in a circuit breaker s disclosed.

Finally, the relatively thin fin in the various embodinents disclosed is disposed so that when the fin is subected to the pressure of hot arc gases during a circuit nterruption :by the associated circuit breaker, the fin is orced more tightly into sealing engagement with the adacent surfaces of the associated housing.

Since numerous changes may be made in the abovelescribed apparatus, and different embodiments of the in- Iention may be made Without departing from the spirit 1nd scope thereof, it is intended that all the matter con- ;ained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. A circuit breaker comprising a housing formed from electrically insulating material having an opening therein for receiving a handle, an operating handle disposed in the opening, an operating mechanism for the circuit breaker disposed in the housing and operatively connected to the operating handle, a slidable member movable with the handle and having an outer surface disposed adjacent to an inner surface of the housing to substantially close the opening, said slidable member formed from an electrically insulating material, and a relatively thin, resilient fin formed integrally with one of the adjacent surfaces of said slidable member and housing around the periphery of the opening to bear against the adjacent surface of the other around the opening in all operating positions of the handle to thereby form a seal between the housing and the slidable member.

2. The combination as claimed in claim 1 wherein the electrically insulating material from which the fin is formed has a relatively low coefficient of friction.

3. The combination as claimed in claim 1 wherein the outer surface of the slidable member and the adjacent inner surface of the housing are both arcuate in configuration.

4. The combination as claimed in claim 1 wherein the fin is formed integrally with the housing.

5. The combination as claimed in claim 1 wherein the fin is for-med integrally with the slidable member.

6. A circuit breaker comprising a housing formed from electrically insulating material having an opening therein for receiving a handle, a slidable member having a handle portion extending through the opening and a closing portion for substantially closing the opening, a generally hollow cylindrical insert member disposed in the opening between the handle portion and the housing with a snap fit and having a flange portion around the opening at the outer surface of the housing, said insert member formed from an electrically insulating material and including an integrally formed, relatively thin, resilient fin around the inner periphery which bears against the closing portion of the slidable member in all positions of the slidable member to thereby form a seal between the slidable member and the housing.

7. The combination as claimed in claim 6 wherein the electrically insulating material from which the insert member is formed has a relatively low coefiicient of friction.

8. A circuit breaker comprising an insulating housing having an opening therein for receiving a handle, an operating mechanism disposed within the housing and including separable contacts which may cause the production of hot arc gases under pressure when separated, an

operating handle disposed in the opening, an insulating slidable member movable with the handle and substantially closing the opening in all positions of the handle, and a relati-velythin, resilient fin having a generally V- shaped cross section formed integrally with the slidable member around the periphery thereof to bear against the inner surface of the housing around the opening at least under the pressure of hot arc gases in all positions of the handle to thereby form a seal between the housing and the slidable member.

9. A circuit breaker comprising a housing formed from electrically insulating material having an opening therein for receiving a handle, a slide disposed adjacent to the opening inside the housing for at all times substantially closing the opening, an operating handle secured to the slide and extending through the opening for operating the slide, and a relatively thin, resilient fin formed integrally with the housing around the periphery of the opening to bear against the slide in all positions of the slide to thereby form a seal between the housing and the slide.

References Cited by the Examiner UNITED STATES PATENTS 2,829,222 4/1958 Dunham 200l68 2,878,347 3/1959 Schmidt 200-468 3,211,877 10/1965 Walker et al 200-168 References Cited by the Applicant UNITED STATES PATENTS 1,547,009 7/1925 Anderson. 2,102,545 12/1937 Rowe. 2,473,848 6/1949 Baxter. 2,568,423 9/1951 Walker et al.

FOREIGN PATENTS 26,899 11/1909 Great Britain.

ROBERT K. SCHAEFER, Primary Examiner.

H. O. JONES, Assistant Examiner.

Claims (1)

1. 9. A CIRCUIT BREAKER COMPRISING A HOUSING FORMED FROM ELECTRICALLY INSULATING MATERIAL HAVING AN OPENING THEREIN FOR RECEIVING A HANDLE, A SLIDE DISPOSED ADJACENT TO THE OPENING INSIDE THE HOUSING FOR AT ALL TIMES SUBSTANTIALLY CLOSING THE OPENING, AN OPERATING HANDLE SECURED TO THE SLIDE AND EXTENDING THROUGH THE OPENING FOR OPERATING THE SLIDE, AND A RELATIVELY THIN, RESILIENT FIN FORMED INTEGRALLY WITH THE HOUSING AROUND THE PERIPHERY OF THE OPENING TO BEAR AGAINST THE SLIDE IN ALL POSITIONS OF THE SLIDE TO THEREBY FORM A SEAL BETWEEN THE HOUSING AND THE SLIDE.

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