US3462716A

US3462716A - Circuit breaker with improved trip structure

Info

Publication number: US3462716A
Application number: US621329A
Authority: US
Inventors: Nick Yorgin; John Majcher
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1967-03-07
Filing date: 1967-03-07
Publication date: 1969-08-19
Anticipated expiration: 1986-08-19
Also published as: US3460075A

Description

Aug. 19, 1969 N. YORGIN ET AL 3,462,715

CIRCUIT BREAKER WITH IMPROVED TRIP STRUCTURE Filed March 7, 1967 5 Sheets-Sheet 1 \T 3? y xii u.

I07 m 29 19 2| I67 W'TNESSES I lNVENTORS I Nick Yorgin a John Mojcher BY a WMAM ATTORNEY YORGIN ET AL 3,462,716

5 Sheets-Sheet 2 Aug. 19, 1969 CIRCUIT BREAKER WITH IMPROVED TRIP STRUCTURE Filed March '2, 1967 FIG.3.

Aug. 19, 1969 N. YORGIN ET AL 3,462,716

CIRCUIT BREAKER WITH IMPROVED TRIP STRUCTURE Filed March 7, 1967 v 3 Sheets-Sheet 5 United States Patent U.S. Cl. 335-23 Claims ABSTRACT OF THE DISCLOSURE A circuit breaker comprising an armature and a trip member positioned to maintain the armature in place which trip member is operated by the armature to trip the breaker upon the occurrence of overload current conditions. An elongated spring member is supported against lateral movement at one end in one of a plurality of slots in the breaker housing and connected at the other end to the armature to bias the armature to a non-tripping position.

Certain features of the circuit breaker disclosed in this application are disclosed and claimed in the copending application of Nick Yorgin et al., Ser. No. 621,321, filed Mar. 7, 1967, and assigned to the assignee of the subject application,

An improved circuit breaker is provided comprising an insulating housing that comprises an insulating troughshaped back base and an insulating trough-shaped front cover supported on the base. The circuit breaker mechanism is supported on the base. A tripping armature, comprising a pair of spaced arm supports, is mounted by being dropped into the base, with the arm supports moving down into a pair of spaced slots formed in the insulating material of the base, to the mounted position wherein the arm supports rest on support surfaces at the back of the slots to pivotally support the armature. A common trip member is mounted on a frame that supports other parts of the circuit breaker mechanism and that is mounted in position after the armature is dropped in place. The trip member, which is operated by operation of the armature to elfect tripping of the breaker, is positioned over the armature to hold the armature captive on the base. Thus, the mechanism is relatively easy to assemble and the magnetic trip can be checked and tested with the circuit breaker cover removed. A simple, reliable and adjustable spring-bias construction comprises an elongated wire-type spring member having the lower end thereof supported against lateral movement in one of a plurality of slots in the base and the other end connected to the armature above the pivot of the armature to bias the armature to the non-tripping position.

An object of this invention is to provide a circuit breaker with improved means for pivotally supporting a tripping armature in position on the housing base.

Another object of this invention is to provide a circuit breaker comprising an improved trip device with improved means for biasing a tripping armature to a nontripping position.

Another object of this invention is to provide an improved circuit breaker with an improved armature biasing means that may be selectively positioned to provide different spring force characteristics.

A further object of this invention is to provide an improved compactly constructed circuit breaker that is relatively easy to assemble and dependable in operation.

These and other objects of the invention will be apparent from the following description when taken in conjunction with the accompanying drawings.

3,462,716 Patented Aug. 19, 1969 ice In said drawings:

FIGURE 1 is a top view, with parts broken away, of a circuit breaker constructed in accordance with the principles of this invention;

FIG. 2 is a sectional view taken generally along the lines 11-11 of FIG. 1;

FIG. 3 is an enlarged view of certain parts seen in FIG.

FIG. 4 is a sectional view, with parts broken away, and with both supporting plates shown in section taken generally along the line IVIV of FIG. 3;

FIG. 5 is a top view of the parts shown in FIG. 3 with parts of both supporting plates shown and with certain parts broken away for purpose of clarity;

FIG. 6 is a view similar to FIG. 3 with parts broken away for the purpose of clarity and with certain parts being shown in the tripped position;

FIG. 7 is a view of certain of the parts shown in FIG. 3 with parts shown in a position reached during a magnetic tripping operation; and

FIG. 8 is a view similar to FIG. 4 with certain parts broken away and with the armature support means being shown.

Referring to the drawings, there is shown, in FIGS. 1 and 2, a two-pole circuit breaker 3 comprising an insulating housing 5 and a circuit-breaker mechanism 7 supported in the housing 5. The housing 5 comprises a trough-shaped back insulating base 9 and a trough-shaped front insulating cover 11 cooperating with the base 9 to enclose the circuit-breaker mechanism 7 that is mounted on the base 9.

The circuit breaker mechanism 7 comprises an operating mechanism 13, a latch mechanism 15 and a thermalend-magnetic trip device 17.

A stationary contact 19, a movable contact 21 and an arc-extinguishing unit 23 are provided for each pole unit of the breaker. The stationary contact 19 for each pole is rigidly mounted on the inner end of a conducting strip 25 that is secured to the base 9 and that extends outward to an external cavity where a well-known type of solderless terminal connector 27 is secured to the outer end of the member 25. The movable contact 21 for each of the pole units is mounted on a contact arm 29 that is pivotally mounted by means of a pin 31 on a switch arm 33 that is fixedly secured to an insulating tie bar 35. The

-switch arms 33 for both pole units are secured to the tie bar 35 for common movement with the tie bar that is pivotally mounted by means of suitable pins in the side walls of the breaker housing. A torsion spring 37 in each pole unit biases the associated contact arm 29 in a clockwise (FIG. 2) direction about the switch arm 33 to provide contact pressure in the closed position of the contacts.

The operating mechanism 13 is a single operating mechanism disposed in the upper (FIG. 1) pole unit. The operating mechanism 13 is supported on two metallic rigid supporting plates 41 that are fixedly secured to the base 9 in the one pole unit of the circuit breaker. Only one of the plates 41 is seen in FIG. 2. An inverted U- shaped operating lever 43 is pivotally supported on the supporting plates 41 with the'inner ends of the legs of the lever 43 positioned in U-shaped notches in the plates 41. An insulating operating member 45 is fixedly supported to the front portion of the operating lever 43. The operating member 45 comprises an insulating shield 47 and a handle 49. The handle 49 protrudes out through an opening 51 in the cover 11, and the shield 47 closes the opening 51 in all positions of the handle.

The switch arm 33 for the center pole unit is operatively connected, by means of a toggle comprising toggle links 53 and 55, to a releasable member or cradle 57 that is pivotally supported on the supporting plates 41 by means of a pin member 59. The toggle links 53, 55 are pivotally connected together by means of a knee pivot pin 61. The toggle link 53 is pivotally connected to the switch arm 33 by means of a pin 63, and the toggle link 55 is pivotally connected to the releasable member 57 by means of a pin 65. Overcenter springs 67 are connected under tension between the knee pivot 61 and the bight portion of the operating lever 43.

The contacts are manually opened by movement of the handle 41 in a counterclockwise (FIG. 2) direction from the ON to the OFF" position. This movement carries the line of action of the overcenter springs 67 to the left causing collapse of the toggle 53, 55 to thereby rotate the tie bar 35 in a counterclockwise direction to simultaneously move the two switch arms 33 to the open position opening the contacts of the two pole units. The contacts are manually closed by reverse movement of the handle 49 from the OFF to the ON position, which movement moves the line of action of the overcenter springs 67 to the right to straighten the toggle 53, 55 to thereby rotate the tie bar 35 in a clockwise direction to move the switch arm 33 of the two pole units to the closed position seen in FIG. 2.

The releasable member 57 is latched in the position seen in FIG. 2 by means of the latch mechanism 15. As is better seen in FIG. 3, the latch mechanism 15 comprises a roller latch member 71 and trip member 73. The roller latch member 71 comprises a generally U-shaped main body part 75 and a roller member 77 movably supported for limited travel on the main body part 75. As can be seen in FIGS. 36, the roller member 77 is provided with pin portions at the opposite ends thereof that fit within elongated slots 79 on the side plates of the main body part 75. A torsion spring member 81 biases the roller member 77 to one end of the slots 79. The rollerlatch member 71 is pivotally supported on the supporting plates 41 by means of a pin member 83. A slot 85, having a lower end 87, is provided in the bight portion of the U-shaped main body part 75 to permit movement of the releasable member 57 between the latched and tripped positions in a manner to be hereinafter described.

The trips member 73 is an insulating trip bar that extends across both of the pole units. It is noted that the trip member 73 is left out of FIG. for the purpose of clarity. As can be understood with reference to FIGS. 1 and 6-8, the trip member 73 is a molded insulating member formed to provide a pair of insulating pin portions 88 that are disposed in suitable openings in the supporting plates 41 to pivotally support the trip member 73 on the supporting plates 41. The trip member 73, which extends through both pole units (FIG. 1) is formed to be supported on only the two supporting plates 41 that are positioned in the one pole unit. As is seen in FIG. 1, although the trip member 73 is provided with

different shapes

73 and 73 in the two pole units, it is noted that this is a unitary member molded as an integral unit to extend across both pole units. The trip member 73 is provided with a latch surface 89, on a hook portion 90 thereof, for engaging a surface 91 on the main body 75 of the roller latch member 71. A compression spring 93 is positioned between the roller latch member 71 and the trip member 73 to bias the trip member 73 in the latching direction. The roller latch member 71 is provided with a stamped-out projection 94 (FIG. 6), and one end of the spring member fits over the projection 94. The trip member 73 is provided with an indentation into which the other end of the spring member 93 fits in order to retain the spring member 93 in position. As can be seen in FIG. 3, the releasable member 57 is provided with a lower hook-shaped end 95 that engages under the roller 77 to latch the releasable member 57.

There is a separate thermal and magnetic trip means 17 in each pole unit. Each of the trip means 17 comprises a generally L-shaped bimetal member 103 having an adjusting screw 105 supported at the upper free end thereof, each of the bimetals 103 is secured to the base 9 by means of a screw member 107, and electrically connected to the associated switch arm 33 by means of a flexible conductor 111. Another flexible conductor 113 (FIG. 2) is connected at one end to the upper end of the associated bimetal 103 and at the other end to the vertical leg of a generally L-shaped conductor 115 that extends through an opening at the one end of the housing. A separate solderless terminal connector 117 is secured to the horizontal leg of each of the conductors 115. Each trip means 117 also comprises a generally U- shaped magnetic member 121 that is welded or otherwise fixedly secured, at the bight portion thereof, to the vertical leg of the associated L-shaped conductor 115. As can be seen in FIGS. 1 and 5, the opposite legs of each U-shaped magnetic member 121 extend on opposite sides of the vertical leg of the associated bimetal 103 to terminate opposite a magnetic armature 123. As can be seen in FIG. 8, each of the armatures 123 comprises a lower attracting part 125 that is positioned opposite the legs of the associated magnetic member 121 (FIG. 2), and a pair of arm portions 127 and 129 (FIG. 8) that rest on ledge parts 131 of the insulating base 9. As can be seen in FIG. 1, the housing base 9 comprises a pair of side walls 133 and a center barrier 135 that extend the length of the base 9 to provide two adjacent compartments for the two pole units of the circuit breaker. The insulating

wall parts

133 and 135 are provided with slots 137 therein (FIG. 8) forming lower shoulder supporting surfaces 131 upon which the arms 127, 129' of the armature 123 rest to provide a pivotal support for the armature 123. Each pole unit is formed with a pair of slots 141 and 143 (FIG. 7) in the base 9. In each pole unit, a spring member 145, that comprises an elongated spring wire member, is mounted in position with the lower end thereof in the slot 141. Each spring member 145 extends upward on the side of the armature 123 that faces the associated magnetic member 121 and is bentover at the upper end thereof (FIG. 7) and passed through an opening 149 (FIG. 8) in the arm 127 of the armature to provide an upper end 151 that engages the armature 123 on the upper side of the pivot 131 and on the side of the armature that is opposite the side that faces the U-shaped magnetic member 121. One leg 127 of each of the armatures 123 is provided with an upper actuating part 155. In each pole unit, the associated spring 145 biases the associated armature 123 in a counterclockwise (FIG. 3) direction about the pivots 131 (FIG. 8) which movement is limited by the engagement of the actuating part 125 of the armature 123 with a stop 159 (FIG. 3) that is molded integral with the housing base 9. As can be seen in FIG. 3, the insulating trip member 73 is formed with a depending projecting part 161 in each pole unit that is positioned adjacent the associated actuating screw 105 and adjacent the associated actuating part of the associated armature.

During the assembly of the circuit breaker, the circuit breaker mechanism 7 is mounted on the base 9 when the cover 11 is removed. The conductor 25, with the termiuals 27 and contact 19 thereon are moved into the position seen in FIG. 2. The arc-extinguishing unit 23 is then dropped in place. A screw member 167 is connected to connect the conductor 25 and arc-extinguishing unit 23 to the base 9. Thereafter, an assembly, comprising the bimetal 103, magnetic member 121, conductor 113, conductor 115, terminal connector 117, tie bar 35, switch arms 33 and contact arms 29 for the two pole units, and the links 53, 55 connected to the one switch arm 33, are dropped down into the base with the ends of the tie bar 35 moving down into hearings in slots in the side walls of the housing base to pivotally support the tie bar 35. The links 53 and 55 are connected to the switch arm 33 of the one pole unit when moved into the mounted position with the tie bar and switch arms. Thereafter, the

armatures 123 of the two pole units are dropped down into position in the slots 137 (FIG. 8). A spring 145 is moved into the mounted position with each armature, with the lower end of the spring being positioned in one of the

slots

141, 143. After the armatures 123 are in the mounted position, the supporting plates 41 with the trip member 73 roller latch member 71 and releasable member 57 connected thereto are moved down into position. Each of the supporting plates 41 comprises two lower supporting foot members that protrude through openings in the base 9 and that are spun over at the external bottom of the base 9 to fixedly secure the supporting plates in position in a Well-known manner. Thereafter, the uppertoggle link 55 is connected to the trip member 5-7 by means of the pin 65. Thereafter, the operating lever 43 with the springs 67 connected thereto are moved into position and the springs 67 are connected to the knee pivot 61. The operating lever 43 pivots in the U-shaped slots of the two supporting plates 41. Thereafter, the insulating member 45 is attached to the front portion of the operating lever 43 and the cover 11 is then moved into the mounted position and secured to the base 9. The cover 11 is provided with side walls that cooperate with the side walls 133 of the base and an insulating barrier portion 171 (FIG. 2) that cooperates with the insulating barrier 135 of the base 9 to divide the housing into two adjacent compartments for the two pole units. As can be seen in FIG. 1, the insulating trip member 73 is molded to form a disc-shaped part 175 that fits in suitable slots in the

barriers

135, 171 to close ofi? the opening in the barriers through which the common trip member 73 passes.

The circuit through each pole unit extends from the terminal connector 117 (FIG. 2) through the conductor 115, the flexible conductor 113, the bimetal 103, the flexible conductor 111, the switch arm 33, the contact arm 29, the contact 21, the contact 19, the conductor 25 to the other terminal connector 27.

When the circuit breaker is in the latched position seen in FIG. 2, the tension springs 67 operate through the toggle link 55 and pivot 65 to force the releasable member 57 in a clockwise direction (FIG. 2) about the pivot 59. counterclockwise movement of the releasable member 57 is restrained by the engagement of the free end 95 (FIG. 3) of the releasable member 57 under the roller member 77 of the roller latch 71 with the releasable member 57 pulling the roller latch member 71 in a clockwise direction about the pivot 83. Clockwise movement of the roller latch member 71 about the pivot 83 is restrained by the engagement of the surface 91 (FIG. 3) of the roller latch 71 with the latch member surface 89 of the trip member 73. The latch surface 89 of the trip member 73 is a surface of the insulating material of the molded insulating trip bar. The force of the roller latch member 71 against the latch surface 89 of the trip member 73 operates through the axis of the pivot 88 of the trip member 73 so that the clock-wise movement of the roller latch member 71 is restrained by the trip member 73 without tending to move the trip member 73 about the axis of the pivotal support 88 of the trip member 73. Thus, the trip member 73 is in a neutral position latching the roller latch member 71 and releasable member 57 in the latched position seen in FIGS. 2 and 3.

Referring to FIG. 3, it will be understood that the releasable member 57 acts on the roller 77 in the direction indicated by the arrow x, which direction is normal to the latch surface of the releasable member 57. The force on the trip member 73 is reduced by the ratio of the lever arm A to the lever arm B. The lever arm A can be made small because the roller 77 reduces the friction between the main body part 75 and the releasable member 57.

The angle of the latch surface 89 is such that when the trip member 73 rotates, the main body part 75 does not move. Thus, the only load that must be overcome during a tripping operation is the bias force on the trip member 73 and the low friction load between the molded insulating latch surface 89 of the trip member 73 and the metallic latch surface 91 of the main body part 75.

The circuit breaker is shown in the closed position in FIG. 2. Upon the occurrence of an overload current above a first predetermined value and below a second predetermined value in any of the pole units, and bimetal 103 in the overloaded pole unit becomes heated and flexes to the right (FIG. 2) with a time delay whereupon the screw 105 engages the associated part 161 (FIG. 3) of the trip member 73 to rotate the trip member 73 in a counterclockwise unlatching direction. During this movement, the latch surface 89 of the trip member 73 clears the latch surface 91 of the roller latch member 71 whereupon the roller latch member 71 is free to move in a clockwise (FIGS. 2 and 3) direction. Upon release of the roller latch member 71, the springs 67 (FIG. 2) operate to rotate the releasable member 57 in a clockwise direction moving the roller latch member 71 and releasable member 57 to the tripped position seen in FIG. 6. The releasable member 57 is stopped in the tripped position when it engages a stop pin 176 (FIG. 2) that is supported on the supporting plates 41.

Upon movement of the releasable member 57 to the tripped position seen in FIG. 6 the line of action of the springs 67 is moved to the left of a line between the

pins

61, 65 and the springs 67 collapse the toggle 55, 53 rotating the switch arm 33 that is attached to the toggle link 53 to move the tie bar 35 and both of the switch arms for the two pole units in a counterclockwise direction opening the contacts of both pole units.

As can be seen in FIG. 6-, in the tripped position the spring 93 tends to move the trip member 73 clockwise which movement is restrained by the engagement of the part 90 of the trip member 73 on the top of the roller latch member 71. The roller latch member 71 is stopped in the position shown in FIG. 6 by a stop projection 176 on one supporting plate 41. When the circuit is interrupted the bimetal 103 cools and straightens to the initial position seen in FIGS. 2 and 6.

Upon the occurrence of a tripping operation the springs 77 maintain the operating lever 43 and handle 49 in a position intermediate the OFF and ON positions in a well known manner to provide a visual indication that the circuit breaker has been tripped.

Before the circuit breaker can be manually operated after an automatic tripping operation, the circuit breaker mechanism must be reset and relatched. Resetting is effected by movement of the handle 49 from the intermediate position to a position slightly past the full OFF position. During this movement, a part 183 (FIG. 2) on the operating lever 43 engages a shoulder portion 185 on the releasable member 57 to rotate the releasable member 57 in a counterclockwise direction about the pivot 59. During this movement, the releasable member 57 moves down in the slot (FIG. 6) in the roller latch member 71 and the end part 95 of the releasable member 57 engages the roller 77 moving the roller 77 in the slot 79 against the bias of the spring 81 to a position which permits movement of the end part 95 of the releasable member 57 past the roller 77, and when the end part 95 of the releasable member '57 passes the roller 77 the torsion spring 81 biases the roller 77 back to the position seen in FIGS. 3 and 6. During this resetting movementof the releasable member 57, the end part 95 of the releasable member 57 engages the surface 87 (FIG. 6) on the part 75' of the roller latch member 71 moving the roller latch member 71 in a counterclockwise direction from the position seen in FIG. 6 to the position seen in FIG. 3. As the roller latch member 71 moves to the position seen in FIG. 3 wherein the bight portion of the roller latch clears the hook end of the trip member 73, the spring 93, which has been additionally charged by counterclockwise movement of the roller latch member 71 biases the trip member 73 in a clockwise (FIG. 3) direction moving the trip member 73 clockwise to the latching position seen in FIG. 3 wherein the surface 89 on the trip member 73 engages the surface 91 on the roller latch member 71 to again latch the parts in the position seen FIGS. 1 and 3. Clockwise movement of the trip member 73 is limited by the engagement of the upper end of the roller latch member 71 with the surface under the hook-shaped part 90 of the trip member 73 as seen in FIGS. 2 and 3. Thereafter, upon release of the handle 49 by the operator, the springs 67 again bias the toggle link 55 to bias the releasable member 57 in a clockwise (FIG. 2) direction to move the trip member up to engage the roller 77 (FIG. 3) in the latched position seen in FIGS. 2 and 3. Thereafter, the handle 49 can be manually moved between the OFF and ON positions to operate the contacts in the manner hereinbefore described.

Upon the occurrence of an overload above the second predetermined value in any of the pole units, the current flowing through the bimetal 103 energizes the associated

magnetic members

121, 123 sufiiciently to attract the armature 123 from the position seen in FIGS. 2 and 3 to the position seen in FIG. 7. During this movement, the armature 123 moves in a clockwise (FIG. 7) direction on the surfaces 131 (FIG. 8) against the bias of the associated spring member 145 and the upper part 155 of the armature 123 engages the part 161 of the trip member 73 to rotate the trip member in a counterclockwise direction from the position seen in FIGS. 2 and 3 to the position seen in FIGS. 6 and 7, whereupon the trip member 73 releases the roller latch member '71 to elfect a magnetic tripping operation in the same manner hereinbefore described with regard to the thermal tripping operation. The magnetic tripping operation is instantaneous as opposed to the time-delay thermal tripping operation. During the tripping movement of the armature 123, the spring 145 is flexed or bowed to the position seen in FIG. 7. As can be seen in FIG. 7, the lower end of the spring 145 is positioned in the slot 141 to prevent lateral movement of the lower end of the spring 145. With the upper end 151 of the spring 145 being moved to the position seen in FIG. 7, and with the part 189 of the armature 123 moving about a fixed pivot 131 (FIG. 8) such that the part 189 engages the spring 145 at 191, the spring 145 is charged to a bowed position in the manner seen in FIG. 7 such that upon interruption of the circuit and deenergization of the

magnetic members

121, 123, the spring 145 discharges from the charged bowed position seen in FIG. 7 to the position seen in FIG. 6 moving the armature 123 counterclockwise from the tripping position of FIG. 7 to the initial position seen in FIG. 6. The circuit breaker is relatched following a magnetic tripping operation in the same manner as was hereinbefore described.

The spring biasing force acting on the armature can be increased by mounting the lower end of the spring 145 in the slot 143 (FIGS. 6 and 7). It is to be understood that a plurality of slots similar to the

slots

141 and 143 could be provided in the base 9 to provide a plurality of adjustments of the biasing force of the spring 145.

From the foregoing, it can be understood that there is provided, by this invention, an improved molded-case or insulating-housing type circuit breaker. The insulating housing comprises an insulatnig base 9 and an insulating front cover 11 supported on the base 9. The circuitbreaker mechanism 7 is supported on the base 9. A tripping armature 123, comprising a pair of spaced arm supports 127, 129 (FIG. 8) is mounted by being dropped into the base with the arm supports moving down into a pair of spaced slots 137 formed in the insulating material of the base, to the mounted position wherein the arm supports 127, 129 rest on support surfaces 131 at the back of the slots 137 to pivotally support the armature. A common trip member 73 is mounted on a frame 41 that supports other parts of the circuit-breaker mecha nism and that is mounted in position after the armature 123 is dropped in place. The trip member 73, which is operated by operation of the armature 123 to trip the breaker, is positioned over the armature 123 to hold the armature captive on the base. Thus, the mechanism is relatively easy to assemble and the magnetic trip can be checked and tested with the circuit-breaker cover 11 removed. A simple, reliable and adjustable springbias construction comprises an elongated wire-type spring member having the lower end thereof supported against lateral movement in one of a plurality of

slots

141, 143 in the base 9 and the other end 151 connected to the armature above the pivot of the armature to bias the armature to the non-tripping position. The lower end of the spring 145 may be selectively positioned to adjust the biasing force of the spring. The compactly constructed circuit-breaker is relatively easy to assemble and dependable in operation.

A two-pole circuit breaker was herein specifically described. It is to be understood that a three-pole circuit breaker could be constructed in accordance with the principles of this invention with a third pole positioned on the opposite side of the pole that houses the single operating mechanism. In this case, the trip member would be extended into the other pole compartment and the tie bar for the contact arms would be extended into the other compartment so that operation of the single operating mechanism would operate all three pole units and tripping movement of the common trip member could be effected by operation of the separate trip means in any of the three pole units. A single pole circuit breaker could be constructed in accordance with the disclosure of FIG. 2 wherein the pole unit that houses the single operating mechanism is disclosed.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details and arrangement of parts may be made without departing from the spirit and scope of the invention.

We claim as our invention:

1. A circuit breaker comprising an insulating housing, said housing comprising an insulating back base and an insulating front cover supported on said back base, said back base comprising a trough-shaped compartment part comprising a back part and a pair of spaced wall parts extending frontward from the back part in a generally parallel spaced relationship, said front cover comprising a trough-shaped compartment part comprising a front part and a pair of spaced wall parts extending backward from the front part in a generally parallel spaced relationship, said front cover being mounted on said back base with said wall parts of said front cover cooperating with said Wall parts of said back base to form opposite walls of a compartment, a circuit-breaker mechanism supported on said back base, said mechanism comprising a pair of contacts and a releasable member releasable to effect automatic opening of said contacts, said mechanism comprising trip means, said trip means comprising a magnetic member and an armature, a pair of spaced armature support surfaces on said spaced wall parts of said back base, said armature comprising a pair of spaced support arms resting on said spaced armature support surfaces to pivotally support said armature on said back base, said mechanism comprising a trip member and means pivotally supporting said trip member with said trip member positioned at the front of said armature to limit frontward movement of said armature, and upon the occurrence of overload current conditons above a predetermined value said armature being attracted to said magnetic member and moving to operate said trip member to eifect release of said releasable member.

2. A circuit breaker according to claim 1, said spaced wall parts of said back base having oppositely disposed slots formed therein open at the front of said back base with said armature support surfaces bing disposed in said slots whereby when said front cover is removed and said trip member is not in the mounted position said armature may be mounted on said back base by being dropped into said slots.

3. A circuit breaker according to claim 2, a pair of supporting plate members supported on said back base, and said trip member being pivotally supported on said supporting plate members.

4. A circuit breaker according to claim 1, said armature comprising a back part on the back side of said armature support surfaces and a front part on the front side of said armature support surfaces, said magnetic member being positioned opposite said back part, and upon the occurrence of overload current conditions above a predetermined value said back part moving toward said magnetic member and said armature pivoting on said armature support surfaces during which movement said front part of said armature engages said trip member to operate said trip member to effect release of said releasable member.

5. A circuit breaker according to claim 4, said spaced wall parts of said back base having oppositely disposed slots formed therein open at the front of said back base with said armature support surfaces being disposed at the back of said slots, and said pair of spaced support arms of said armature being positioned in said oppositely disposed slots and resting on said armature support surfaces to pivotally support said armature on said back base.

6. A circuit breaker comprising an insulating housing, said insulating housing comprising a back base and a front cover, said back base comprising a trough-shaped compartment part comprising a back part and a pair of spaced wall parts extending frontward from the back part in a generally parallel spaced relationship, said front cover comprising a front part and a pair of spaced wall parts extending backward from the front part in a generally parallel spaced relationship, said front cover being mounted on said back base with said wall parts of said front cover cooperating with said wall parts of said back base to form opposite walls of a compartment, a circuit-breaker mechanism support in said housing on said back base, said mechanism comprising a latched releasable member releasable to efiect automatic opening of said contacts, said mechanism comprising trip means, said trip means comprising a magnetic member and an armature, a pair of spaced armature support surfaces on said spaced wall parts of said back base, said armature comprising a pair of spaced support arms resting on said spaced armature support surfaces to pivotally support said armature on said back base, an elongated spring member, a first spring support means on said back part of said back base supporting one end of said spring member against lateral movement, and the other end of said spring member engaging said armature on the front side of said spaced armature support surfaces to bias said armature to an initial non-tripping position, upon the occurrence of overload current conditions above a predetermined value said armature pivoting on said spaced armature support surfaces to a tripping position to effect release of said releasable member during which movement said armature bows said spring member to charge said spring member whereby upon opening of said contacts said charged spring member discharges to return said armature to the initial position.

7. A circuit breaker according to claim 6, and said first spring support means being a slot in said back part of said back base of said insulating housing with said one end of said spring member being positioned in said slot and restrained in said slot against lateral movement.

8. A circuit breaker according to claim 6, said armature comprising a back part on the back side of said spaced armature support surfaces and a front part on the front side of said spaced armature support surfaces, said magnetic member being positioned on one side of said armature on the back side of said spaced armature support surfaces, said armature having an opening therein at the front side of said spaced armature support surfaces, said spring member extending from the back side to the front side of said spaced armature support surfaces on the side of said armature that faces said magnetic member with said spring member at the front side of said spaced armature support surfaces extending through said opening in said armature to engage said armature on the side of said armature that is opposite the side that faces said magnetic member, upon the occurrence of overload current conditions above a predetermined value said back side of said armature being attracted to said magnetic member and said armature pivoting on said spaced armature support surfaces during which movement a part of said armature intermediate the front and back ends of said armature engages a part of said spring member intermediate the front and back ends of said spring member and during which movement the front end of said spring member is moved with the front of said armature whereby said spring member is bowed along the length thereof to thereby charge said spring member whereby when said contacts are opened said charged spring member discharges to return said armature to the initial position.

9. A circuit-breaker according to claim 8, said back base of said insulating housing having a plurality of aligned slots therein, said first spring support means being the positioning of said one end of said spring member in one of said plurality of aligned slots, and said one end of said spring member being positionable in another of said plurality of aligned slots to adjust the biasing force of said spring member.

10. A circuit-breaker according to claim 1, said circuit-breaker comprising a multi-pole circuit-breaker with a separate pair of contacts for each pole, said back base at each pole comprising a pair of said spaced wall parts with oppositely disposed slots formed in each of said pair of spaced wall parts open at the front of said back base, a pair of spaced armature support surfaces in each of said pair of slots, a separate magnetic member and a separate armature for each of said poles, each of said armatures comprising a pair of spaced support arms in the associated pair of slots resting on the associated spaced armature support surfaces to pivotally support the armature on said back base, said trip member comprising a single trip member common to all of said pole units positioned at the front of all of said armatures to limit frontward movement of all of said armatures and said front cover comprising a pair of spaced wall parts for each pole with each pair of spaced wall parts of said front cover cooperating with a separate pair of spaced wall parts of said back base to form opposite walls of a compartment.

References Cited UNITED STATES PATENTS 3,278,708 10/1966 Casey 335-35 BERNARD A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner