US 3559120 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Jan. 26, "1 971 F. E. MYERS CIRCUIT BREAKER WITH INTERCHANGE'ABLE PLUG-IN TYPE TRIP UNIT SUB-ASSEMBLY 6; Sheets-Sheet -1 Filed April 2"1 1969 INVENTOR. FZ/J M14595 wvaen irs Jan. 26, 1971 1-; MYERS CIRCUIT BREAKER WITH INTERCHANGEABLE PLUG TYPE TRIP UNIT SUB-ASSEMBLY Filed April 21, 1969 6 Sheets-Sheet 2' wuw MYERS Jan. 26, 1971 CIRCUIT BREAKER WITH INTERCHANGEABLE PLUG TYPE TRIP UNIT SUB-ASSEMBLY 6 Sheets-Sheet s- 7 Filed April 21, 1969 NNK MWK
" HF. E. MYERS cmcurr BREAKER WITH mmncuANGmBLr: PLUG-PIN TYPE 1313; UNITY sun-553mm, 1 v
riledg iili 1, 196 9 1 IYINVENI'ORL fZ/J 5 M aes Jan. 26, 1971 F, MYERS 3,559,120 j CIRCUIT BREAKER WITH INTERCHANGEABLE PLUG-IN TYPE TRIP UNIT SUB-ASSEMBLY I Filed April 21, 1969 6 Sheets-Sheet" 5- I I F s5 v .MN.
F. E. MYERS CIRCUIT BREAKER WITH INTERCHANGEABLE PLUG Jan. 26, 1971 TYPE TRIP UNIT SUB-ASSEMBLY Filed April 21, 1969 6 Sheets-Sheet 6 M a .w M w W5 4 W [V 6 N a a bM i f v 4 r m: m y M W L f 6 F M w \\.w w m Thum V W II H Patented Jan. 26, 1971 3,559,120 CIRCUIT BREAKER WITH INTERCHANGEABLE PLUG-IN TYPE TRIP UNIT SUB-ASSEMBLY Felix E. Myers, Cherry Hill, N.J., assignor to I-T-E Imperial Corporation, Philadelphia, Pa., a corporation of Delaware Filed Apr. 21, 1969, Ser. No. 817,775 Int. Cl. H01h 71/74 U.S. Cl. 335-42 6 Claims ABSTRACT OF THE DISCLOSURE In a circuit breaker of the size and type intended for home or industrial use, an interchangeable plug-in trip unit sub-assembly is provided to readily permit a variation in the circuit breaker tripping characteristics. In the disclosed embodiments the replaceable trip unit subassembly constitutes a portion of the magnetically actuated tripping means. In one embodiment, the magnet and energizing coil is replaceable and in another embodiment the entire assembly including the energizing coil, magnet, and cooperating armature is replaceable.
My invention relates to circuit breakers and more particularly to circuit breakers of the size and type intended for home or industrial use.
Circuit breakers of the type to which my invention is particularly applicable are typically shown in my US. Patent No. 2,996,589 issued Aug. 15, 1961, entitled Pivoted Bimetal, and U.S. Patent application filed in the name of Carl E. Gryctko, Ser. No. 647,999, June 22, 1967 and now abandoned, both assigned to the I-T-E Circuit Breaker Company. It should, however, be understood that the reference to these presently available commercial circuit breaker constructions which may be modified to include my invention is not intended as a limitation of my invention, but the novel aspects of my arrangement may be practiced in conjunction with numerous other circuit breaker constructions of the type generally intended for home or industrial use.
Such circuit breakers generally include a molded housing with recesses for operatively locating and enclosing all the circuit breaker components. The circuit breaker components typically include at least one pair of cooperating contacts, a latchable-operati-ng means for rapidly moving the contacts between their engaged and disengaged conditions responsive to predetermined fault conditions responsive to predetermined fault conditions, an overload responsive trip means for sensing the occurrence of the predetermined fault condition and a manual operating means. The overload responsive trip means may typically include a magnetic trip, with the energizing current for the magnet being operatively proportional to the current flow through the circuit breaker. When the current flow reaches a predetermined magnitude the force of attraction between the magnet pole faces and its cooperating armature is sufficient to defeat the biasing force of the armature and thereby draw the armature towards the magnet. As the armature moves toward the magnet it engages the latch to thereby defeat the latched engagement. Such circuit breakers may also, when desirable, include an overload responsive bimetallic element. The bimetallic element is heated by a current proportionally related to the current flow through the circuit breaker. When a predetermined sustained overload condition exists the bimetallic element will deflect sufliciently to defeat the latch.
In the prior art circuit breakers of the type intended for such home or light industrial use all the circuit breaker components, including the complete overload responsive trip means, are completely encased within the sealed housing. Thus, it has heretofore been necessary to construct and stock different overall circuit breaker units in accordance with various ratings of the circuit. That is, such circuit breakers are generally available in ratings such as 10, 15, 20, 20, 50 and amperes. I have recognized that the same circuit breaker construction may be used for different ratings merely by changing one or more of the components of the overload responsive trip means. For example, if a circuit breaker is constructed to safely withstand the current flow and interruption associated with a rating up to 50 amperes, the modification of such circuit breaker to have a 30, 20, 15 or 10 ampere rating may be achieved by merely changing the characteristic of the overload responsive trip means. Thus, my present invention would permit the manufacture, stocking and distribution of one basic circuit breaker frame for a wide variety of ampere ratings. A plug-in subassembly would then be inserted to provide the particular desired tripping characteristic.
The general idea of a replaceable trip unit assembly has heretofore been available only with substantially larger frame circuit breakers, as for example the type shown in U.S. Patent No. 3,319,195, issued May 5, 1967 in the name of Albert Strobel and John C. Bromfield, and entitled Circuit Breaker Trip Unit Assembly. Such a separate trip unit assembly is normally mounted upon the base of the substantially larger frame circuit breaker (as compared to the frame size of the present invention), and separate housing cover portions must then be bolted to the base to enclose the trip unit assembly and the housing.
In accordance with my invention the housing advantageously includes a pocket-type opening and the interchangeable sub-assembly includes wall surfaces which are complementary with the housing wall surfaces about the complementary opening for completely sealing the opening and enclosing the circuit breaker components. That is when the interchangeable sub-assembly is located within the pocket-type opening of the circuit breaker, it serves to completely close the opening, thereby avoiding the need for any supplementary housing portions, as typically required in the larger frame circuit breakers which have a separate base and cover portions.
In accordance with a further advantageous feature of the present invention, the overload responsive trip means includes an externally accessible calibration means for adjusting, within a predetermined range, the tripping characteristic established by the sub-assembly. This is illustratively shown as being accomplished by varying the initial armature air gap separation. The latch bite may also be adjusted either alone or in conjunction with the armature air gap separation.
It is, therefore, seen that the present invention principally resides in providing interchangeable trip unit characteristics in a circuit breaker of the size and type intended for a home or light industrial use.
It is, therefore, a principal object of the instant invention to provide an improved circuit breaker having an interchangeable trip unit.
A further object of the present invention is to provide a circuit breaker of the type intended for home or industrial use which includes an interchangeable trip means to permit a variation of the tripping characteristics.
Another object of the present invention is to provide a circuit breaker of the type intended for home or industrial use, which includes an externally accessible pocket type opening for receiving a sub assembly which controls the tripping characteristics of the circuit breaker, with said sub-assembly also serving to seal the circuit breaker housing opening.
An additional object of the present invention is to provide a circuit breaker of the type intended for home or industrial use in which the magnetic trip portion thereof includes a plug-in type of interchangeable sub-assembly for modifying the circuit breaker tripping characteristics.
These as well as other objects of the present invention will be readily apparent from the following descriptions and drawings in which:
FIG. 1 is a cross-sectional view of a completely assembled circuit breaker constructed in accordance with one embodiment of my invention.
FIG. 2 is an exploded perspective view of the circuit breaker housing and sub-assembly portions of the embodiment shown in FIG. 1, to illustrate the manner in which the sub-assembly is inserted within the circuit breaker pocket-type opening.
FIG. 2A is a cross-sectional view along the line 2A-2A of FIG. 1.
FIGS. 3, 4 and 5 are plan, front and bottom views, respectively, of the completely assembled circuit breaker shown in FIGS. 1 and 2.
FIG. 6 shows the overload responsive trip means and latch portion of the circuit breaker shown in FIG. 1, with a calibration adjustment having been made of the armature air gap.
FIGS. 7, 8 and 9 are side, front and top views, respectively, of the self-contained sub-assembly portion utilized in conjunction with the embodiment of FIGS. 1 through 6.
FIG. 7A is a side view of a plug-in sub-assembly having a different tripping characteristic.
FIG. 10 is a cross-sectional view of a circuit breaker constructed in accordance with another embodiment of my invention.
FIG. 11 is an exploded perspective view showing the inter-relationship of the circuit breaker housing and the self-contained sub-assembly of the FIG. 10 embodiment.
FIGS. 12, 13 and 14 are plan, front and bottom views, respectively, of the assembled circuit breaker in accordance with FIGS. 10 and 11.
FIGS. 15 and 16 are side and front views, respectively, of the self-contained sub-assembly utilized in conjunction with the embodiments of FIGS. 10 through 14.
Referring initially to the embodiment of FIGS. 1 through 9, circuit breaker 20 is of the general type shown in aforementioned US. patent application in that it includes a separate circuit breaker portion and current limiting fuse. It should, however, be understood that the fuse portion may be deleted with the instant invention being applicable to a device including only the circuit breaker portion, as shown in aforementioned US. Pat. 2,996,589. Likewise, the particular structural details of the circuit breaker are merely for illustrative purposes and it should be readily appreciated that the present invention is adaptable to other circuit breaker constructions. Such circuit breakers may typically have the following dimensions (referring to FIG. 2): a width W in the order of one inch; a depth D in the order of two inches; and an overall length L in the order of three and a half inches. Should the current limiting fuse portion be deleted, the overall length may generally be in the order of three inches. It should be understood that these dimensions are not given as critical limitations of the present invention, but merely represent a guide to understand the nature of the compact circuit breaker to which the instant invention has demonstrated particular utility.
Circuit breaker 20 is constructed within a molded housing including a base section 22 and complementary cover 24. The molded housing thus includes a pair of opposed top and bottom walls 30, 3 2, respectively; a pair of 0pposed first and second side walls 34, 36; and a pair of opposed front and rear walls 38, 40. The housing sections are held together by rivets 26. The internal volume bounded by the above noted walls is separated into two compartments by a dividing region generally shown by the dotted line 42. The first compartment 44 includes a circuit breaker device generally constructed in accordance with aforementioned US. Pat. No. 2,996,589 except for the pluggable trip unit assembly 150 of the instant invention. The longitudinally adjacent second compartment 46 contains a current limiting fuse 50 having characteristics operatively related to the circuit breaker device as is the subject of aforementioned US patent application Ser. No. 647,999 and now abandoned.
The circuit breaker 20 includes a line terminal which is suitably connected to a source of electrical energy, e.g. the bus bar of a panel board. Line terminal 100* is connected via electrical conductor portion 101 to the stationary contact 102. Cooperating with stationary contact 102 is a movable contact 104 connected to the lower end of a bifurcated contact arm 106. Parallel plate are extinguishing means 108 is provided in recesses 109. The upper end of the bifurcated contact arm abuts a suitable pivot formation of internally extending portion 112 of manual operating member 114. Manual operating member 114 is pivoted about a housing protrusion 113 which is entered into suitable recesses of the molded base 22 and cover 24. The manual operating member 114 includes an outwardly extending portion 116 for manually moving the circuit breaker between its manual Off and manual On positions, as well as for resetting the breaker after a trip operation, in the manner fully set forth in aforementioned US. Patent No. 2,996,589.
The contact carrying arm 106 has a braid member 120, with the opposite end of the braid member being connected to internal contact finger 122. Another contact finger 127 is provided such that contact fingers 122 and 124 will engage complementary elements 123, 125 of the sub-assembly portion 150. Sub-assembly portion 150, as will be more fully discussed, includes an energizing coil 152 for the magnet for the magnetically actuated circuit breaker fault responsive trip means. The current path then continues through the coil 152 and contact 127 to conductor 132 which has a tulip-type clip portion 133, for engaging the upper ferrule terminal 134 of the fuse 50. The lower ferrule terminal 136 of the fuse is in turn connected to tulip-type terminal 138, which is connected via conductor portion 139 to the externally accessible load terminal 140.
The operating mechanism for bringing about the engagement and disengagement of the cooperating contacts 102, 104 comprises a latchable cradle member 141 which is pivotally mounted at one end thereof to base protrusion 142. Cradle 141 also carries a kicker 145 which gives contact arm 106 a hammer-like blow during the tripping operation to ensure separation of the circuit breaker contacts.
One end of an operating spring 148 is connected to cradle 141 at aperture 150, while the other end of the operating spring is connected to contact arm 106 at aperture 152. Operating spring 148 is always in tension, thereby urging contact arm end 115 upwardly into engagement with its pivotal mounting to manual operating member 114, and latchable cradle member 141 clockwise about its pivotal mounting 142. The force of operating spring 148, relative to the pivotal mounting of contact arm 106, also serves to urge the movable contact 104 into firm engagement with its cooperating stationary contact 102 to provide the necessary contact engagement forces.
Latchable cradle 141 includes a latchable tip 144 which seats upon Iatch portion 154 carried by the lower end of an elongated latching member 124. A bearing pin 156 is suitably secured to an intermediate region of elongated latching member 124, as by welding, and enters suitable circular recesses of the circuit breaker base 22 and cover 24 for pivotally mounting the latching member 124. The latching member 124 is biased in a clockwise direction about its pivot 156 by spring 158. Calibrated adjustment of the trip unit, with the insertion of a particular plug-in sub-assembly 150, is obtained by calibrating screw 160 which bears against intermediate connecting member 162 to modify the latch bite.
If desired, the latching member 124 may be formed of a bimetallic element, and suitably heated in a manner proportionally related to the current flow through the circuit breaker, as shown in aforementioned US. patent application 647,999 and now abandoned.
As discussed in aforementioned US. patent application Ser. No. 647,999 and now abandoned the fuse member 50 is retained within a rotatable fuse holder 210, which has a cam surface 212 along the underside thereof. Cam surface 212 cooperates with interlock trip lever 215, and its associated biasing means 217, to permit counterclockwise movement about its pivot 219, in the event of fuse removal, such that end 221 thereof engages the latching lever 124, for tripping the circuit breaker upon such fuse removal.
In accordance with the instant invention, the overload responsive trip means includes a plug-in type and selfcontained sub-assembly 150. This sub-assembly is shown provided in conjunction with the magnetically actuated trip means. Sub-assembly 150 includes a magnet comprising a magnet bottom plate 160, top plate 162, magnet in 164, and mounting block 168. The energizing coil 152 is located about the pin 164 between the upper and lower plates 160, 162. The ends of the coil are connected to finger type terminals 123, 125 located by insulative means 121. Terminals 123, 125 make contact with internally located conductors 122, 127 within the pocket-type opening 200.
The magnetic assembly located within sub-assembly 150 therefore includes opposed pole faces 161, 163. These operate in conjunction with armature member 170, pivotally mounted within the circuit breaker housing at 171 and biased by spring 173. When the armature member 170 is drawn towards the cooperating pole faces 161, 162 of the magnet, the extension 175 thereof will engage the lower region of the latching member 124, to thereby defeat the latching engagement between cradle tip 144 and latching ledge 154.
In accordance with an extremely advantageous feature of my invention, the initial air gap separation between armature 170 and pole faces 161, 163 may be calibrated by externally accessible button member 180. Button member 180 is rotated within recess 182 of the circuit breaker top wall 30, and is rotatable about axis 181, as by a screwdriver insertable in slot 183. Button 180 is maintained in its position by spring member 184 which abuts shoulder portion 185 thereof. An internal eccentric opening 187 is provided in button member 180, having the configuration shown in FIG. 2A.
The calibration adjustment further includes an intermediate connecting lever 190, pivotally mounted about 192. Member 190 is biased counterclockwise about pivot 192 by spring member 195, mounted on hearing 156. The extent of clockwise movement of the intermediate calibration member 190 is limited by its engagement with upstanding wall 188 of the eccentric calibration opening 187. End 195 of calibration lever 140 abuts the rear of the armature 170, and thereby limits its counterclockwise movement about pivot 171, under the influence of biasing means 173. Hence, it should be recognized that the permissible movement of calibration member 190, as controlled by the position of externally accessible adjustment 180, provides a variation of the initial air gap between the extremes shown in FIGS. 1 and 6. That is, FIG. 1 corresponds to the High setting of the circuit breaker. The maximum armature air gap separation requires the maximum energization to cause attraction of armature 170 to the cooperating pole faces 161, 163. Conversely, with a minimum air gap separation as shown in FIG. 6, the reluctance of the magnetic circuit is significantly decreased, thereby requiring lesser magnetization current in order to attract armature 170 to the magnet.
The lower housing wall 32 includes a pocket-type opening 200, for the reception of the sub-assembly 150. Subassembly 150 is of such a configuration that when it is properly inserted (such that contact fingers 123, are in electrical contact with interior located contact elements 122, 127) the housing will be completely enclosed, as shown in FIGS. 3-5. It should be readily recognized that by substituting another sub-assembly (FIG. 7A) having a different energizing coil characteristic (e.g. substantially lesser turns), the rating of the circuit breaker will be increased. Hence, it is seen that the present invention readily permits a change in the circuit breaker rating by merely removing one sub-assembly 150 of the trip unit and inserting another sub-assembly 150', having the same dimensional configuration, but different electrical characteristics.
Reference is now made to FIGS. 10 through 16, which show another embodiment 20' of circuit breaker constructed in accordance with my invention. The circuit breaker 20' differs from circuit breaker 20 of the FIGS. l-9 embodiment, principally in that the sub-assembly 250 includes the entire magnetically responsive trip means and calibration, instead of containing only the magnet portion thereof. Those portions of circuit breaker 20' which are identical with circuit breaker 20 are similarly numbered. Thus, it should be noted that the fuse compartment 46 is unchanged, as well as the basic circuit breaker operating mechanism including cradle member 141, spring 148, operating handle 114 and cooperating contact pairs 22, 24.
The latching member 124 is pivotally mounted at bearing 156 and similarly includes a latching ledge 154 which engages the cradle tip 144. The interlock for effecting tripping of the circuit breaker upon the removal of fuse holder 210 is now obtained by interlock lever 225, which is pivoted at 156. Interlock lever 225 includes a cam follower portion 227 at one end thereof, which is moved by cam surface 212 of the fuse holder, against the bias of spring 229. Upon removal of fuse holder 210, the lever 225 rotates counterclockwise about pivot 156 moving the end 231 into engagement with the upper end of the latching member 124, to effect counterclockwise movement of 124 about 156 and defeat of the latching engagement between cradle tip 144 and latching ledge 141.
The sub-assembly 250 includes the entire magnetically responsive trip means, as well as the calibration adjustment thereof. Mounting base 252 thereof is of a configuration, such that when it is located within the circuit breaker pocket opening 251, it completely seals the side and bottom walls of the opening 251, so as to enclose the circuit breaker. A U-clip 254 is located within grooves 255 of the mounting bases 252. Grooves 255 are in registry with grooves 257 of the circuit breaker front and rear walls, such that U-shaped member 254, when moved into groove 257 (see FIGS. 13 and 14) serves to maintain the sub-assembly 250 within the housing opening. The body region 253 of the U-shaped clip, when inserted, sits in groove 259 across the bottom wall of the circuit breaker housing.
The sub-assembly 250 includes a magnet portion having upper magnet member 260, lower magnet member 261, interconnecting member 262, and energizing coil 264. Pivotally mounted in suitable recesses 266, within the lower magnet member is the armature member 270, biased away from the magnet pole faces by U-shaped spring member 282. The electrical interconnection of the subassembly coil 264 with the circuit breaker current path is obtained by contact elements 272, 274, which engage cooperating contact elements 273, 275, respectively, within the circuit breaker opening.
The initial air gap calibration of the magnetically actuated overload responsive trip means is obtained by wheel-like calibration member 290, which extends through housing opening 293. Wheel 290 includes a camming surface 291, which engages cam follower portion 293 of the calibration lever 294. Calibration lever 294 is pivotally mounted at pin 296 and biased counterclockwise by spring member 298. The opposite end 295 of the lever 294 engages inwardly turned ear portion 271 of the armature, thereby providing a range of adjustment shown between the dotted conditions of FIG. 16.
It should now be readily apparent that the insertion of the entire sub-assembly 250 modifies the entire tripping characteristics of the circuit breaker, with the entire magnetically actuated overload trip means as well as its external calibration being mounted as a self-contained subassembly 250.
Although there has been described preferred embodiments of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited, not by the specific disclosure herein, but only by the appending claims.
What is claimed is:
1. A circuit breaker of the type intended for home or industrial use comprising:
a housing for operatively locating and enclosing the circuit breaker components, said components in cluding:
at least one pair of cooperating contacts;
an operating means for moving said contacts between their engaged and disengaged conditions, responsive to at least one type of predetermined fault condition;
an overload responsive trip means for sensing the occurrence of said predetermined fault condition and initiating movement of said operating means to the contact disengaged TRIP condition, said overload responsive trip means including magnetically actuated means having magnet, armature and energizing coil elements operatively responsive to the current flow through said circuit breaker;
the improvement comprising:
said overload responsive trip means including at least a portion constructed as an integral self-contained plug-in type sub-assembly;
said circuit breaker housing including an externally accessible pocket type opening for receiving said sub-assembly;
means for electrically and mechanically interconnecting said sub-assembly to the remaining circuit breaker parts internal of said housing in a manner per- 8 mitting ready removal of said sub-assembly for replacement by another sub-assembly;
said sub-assembly including at least one of the elements of said magnetically actuated means for establishing the trip characteristics of said overload responsive means, such that replacement of the sub-assemblzy alters the circuit breaker trip rating;
said sub-assembly including wall surfaces complementary with said housing wall surfaces about said opening for completely sealing said opening and enclosing the circuit breaker components.
2. In a circuit breaker of the type set forth in claim 1,
further including externally accessible calibration means for adjusting the initial air gap separation between the pole faces of said magnet element and said armature element to vary the trip characteristics established by said subassembly about a predetermined range.
3. In a circuit breaker of the type set forth in claim 1,
said sub-assembly including said energizing coil element such that the trip rating of said circuit breaker varies as different sub-assemblies of differing energizing coil characteristics are substituted as part of said overload responsive trip means.
4. In a circuit breaker of the type set forth in claim 1,
said sub-assembly including all of said magnet, armature and energizing coil elements.
5. In a circuit breaker of the type described in claim 1,
said circuit breaker housing having a width in the order of one inch.
6. In a circuit breaker of the type described in claim 1,
said circuit breaker housing having a Width in the order of one inch, and a depth in the order of 2 /2 inches.
References Cited UNITED STATES PATENTS 2,982,834 5/1961 Edmunds 337 71 3,354,277 11/1967 Stanback 337 210 HAROLD BROOME, Primary Examiner U.S. Cl. X.R. 335-176