US2701829A

US2701829A - Manually operable circuit breaker

Info

Publication number: US2701829A
Application number: US240138A
Authority: US
Inventors: Alvin W Krieger
Original assignee: Cutler Hammer Inc
Current assignee: Cutler Hammer Inc
Priority date: 1951-08-03
Filing date: 1951-08-03
Publication date: 1955-02-08
Anticipated expiration: 1972-02-08
Also published as: GB739380A

Description

Feb. 8, 1955 A. w. KRIEGER 2,701,829

MANUALLY OPERABLE CIRCUIT BREAKER Filed Aug. 3, 1951 4 Shets-Sheet l -rf-" (e I lI Il (O 34 A la 14 4b 4a 43 i I f da l 4Z Z4- 40H) Z0 ZZ 8 z i 54o lill] g la l 'gI wa l" I 4 34\ 5 l 5 b FIQZ. '78WL b zc" lo 2e az 5 @a '7,2 24 84N: Nkg 5o Flex. IEMMETALIMO :'III 'lo za 3e, 4* Iv' 34 l 4 Zo 62 4:4 Ill A ze 8 Il 224:4 Fleh I4 4b l, I 54 24 *la 84 g8 8 32 74 |l 65 36 4 5725'META JNVENTOR. 4|. 34 11| ALVIN W. KRIEGER 2 0 'l' BY 2b ZZ 62 76 ATTO .Y

Feb. 8, 1955 A w, KR|EG|-2R 2,701,829

MANUALLY OPERABLE CIRCUIT BREAKER Filed Aug. 5, 1951 4 Sheets-Sheet 2 INVENTOR. ALvm W. KNEQER mb AT ORHEZY Feb- 8, 1955 A. w. KRIEGER MANUALLY OPERABLE CIRCUIT BREAKER Filed Ag. 5, 1951 4 Sheets-Sheet I5 ATToRNaY Feb. 8, 1955 A. w. xml-:GER 2,701,829

MANUALLY OPERABLE CIRCUIT BREAKER Filed Aug. 5, 1951 4 Sheets-Sheet 4 A LA) 1 N W. KRmGER ATTORNEY United States Patent O 2,701,829 MANUALLY OPERABLE CIRCUIT BREAKER Alvin W. Krieger, Milwaukee, Wis., assignor to Cutler- Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Application August 3, 1951, Serial N o. 240,138 24 Claims. (Cl. 200-116) This invention relates to manually operable circuit breakers having automatic overload tripping mechanisms, and particularly to such circuit breakers which are opened and closed with a snap action by a push-pull type of operating button.

Circuit breakers of this type have heretofore used current-responsive latches which directly contact the movable contact carrying member to hold the switch on during normal operation. Because of the extreme work required of such latches the time limits and current Values are relatively high and such breakers cannot be used where low, close limits are required. In the normal operation of such breakers it is necessary to mechanically deflect the current-responsive latch for each opening and closing. This shortens the elfective life of the latch. In addition, such breakers may be manually held on even when the latch has tripped.

The objects of this invention, therefore, are to provide a circuit breaker which: will trip automatically within close limits of time and current values; may be normally manually operated operated with double snap action without disturbing the current-tripping mechanism; is reset after automatic tripping by the same manual operation used to close the circuit breaker; will be free tripping, that is it will automatically trip even though normally manually held closed, and will not close when tripping conditions exist; will have relatively high current rupturing capacity; and will not be a re hazard.

In obtaining these objects a double snap-action switch is operated by moving its over-center spring under the control of a manually movable member. Such member may be of the push-pull type and is manually moved to and from on and off positions.

An overload release spring acting through a slider urges the manually movable member toward 011. However, the slider is normally latched with the over load release spring loaded as the manually movable member is moved to on position. When the slider is latched the manually movable member may move from on and ott positions in the normal operation of the switch without disturing the latched condition of the slider.

The latch for the slider consists of an engagement between the slider and a suitable relatively fixed abutment. This engagement is relatively hard to overcome because of the friction created by the force of the release spring. Hence a spring-biased trigger is used to supply the force for unlatching the slider. The trigger is held in cocked position by a current-responsive element. The spring for operating the trigger is weaker than the release spring and hence the frictional engagement between the currentresponsive element and the trigger is much lower. It is preferable to use a long trigger with the place of engagement with the current-responsive element remote from the trigger spring. This also lessens the frictional engagement between such element and the trigger and permits the element to release the' trigger within close limits of time and current values. When released, the trigger develops enough momentum or multiplied force to readily overcome the frictional resistance between the latch and slider and disengage the latter. Upon such disengagement the release spring will move the manually movable member to off position.

An abutment is provided on the manually movable member to engage and automatically reset the trigger in cocked position as the manually movable member is moved to off position. As the manually movable member is manually moved to on position the snap action switch will be closed unless the current-responsive member is still in overload position. In such event the trigger will not stay in cocked position and will engage 2,701,829 Patented Feb. 8, 1955 the movable switch contact and hold the switch open as the manually movable member moves into on position. To accomplish this there is a linger on the trigger to engage and hold the movable contact open even though the manually operable member is moved to fully on position. The trigger spring supplies a greater force than the over-center spring. Thus there is accomplished a free tripping action so that the switch cannot be closed when tripping conditions exist.

'l'he novel features, which are considered characteristic of the invention, are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

Fig. l is a view in side elevation of the rst modification of the circuit breaker embodying the present invention with the side of the base cut away and shown in section for clarity in illustration, the parts being shown in "on position for normal operation;

Fig. 2 is a view similar to Fig. 1 with the circuit breaker olf and the parts shown in the position assumed after the overload release has functioned;

Fig. 3 is a view similar to Fig. 1 with the circuit breaker off and the parts shown in the position assumed during the first step following the release of the overload mechanism, such position being the same as in the case where the push-pull bar has been manually moved to or held in the on position during overload'conditions;

Fig. 4 is an exploded view of the slider and trigger mechanism constituting part of the overload release mechanism;

Fig. 5 is a sectional view taken on line 5-5 of Fig. l;

Fig. 6 is a View in side elevation of the second modification of the circuit breaker embodying the present invention with the side of the base cut away and shown in section for clarity in illustration, the parts being shown in on position for normal operation;

Fig. 7 is a View similar to Fig. 6 with the circuit breaker ott and the parts shown in the position assumed during the first step following the release of the overload mechanism, such position being the same as in the case where the push-pull bar has been manually moved to or held in the on position during overload conditions;

Fig. 8 is a view similar to Fig. 6 with the circuit breaker oi and the parts shown in the position assumed after the overload release has functioned;

Fig. 9 is an exploded view of the slider and trigger mechanism constituting part of the overload release mechanism;

10 is a sectional view taken on line 10-10 of 1g.

Fig. l1 is a view in side elevation of the third modification of the circuit breaker embodying the present invention with the side of the base cut away and shown in section for clarity in illustration, the parts being shown in on position for normal operation;

Fig. 12 is a view similar to Fig. l1 with the circuit breaker olf and the parts shown in the position assumed after the overload release has functioned;

Fig. 13 is a view similar to Fig. 11 with the circuit breaker off and the parts shown in the position assumed during the first step following the release of the overload mechanism, such position being the same as in the case where the push-pull bar has been manually moved to or held in the on position during overload conditions;

Fig. 14 is an exploded view of the slider and trigger mechanism constituting part of the overload release mechanism;

FFig1 15 is a sectional view taken on line 15-15 of 16 is a sectional view taken on line 16-16 of 1g.

Fig. 17 is a view in side elevation of the fourth modiiication of the circuit breaker embodying the present invention with the side of the base cut away and shown in section for clarity in illustration, the parts being shown in on position for normal operation;

Fig. 18 is a view similar to Fig. 17 with the circuit breaker off and the parts shown in the position assumed during the first step following the release of the overload mechanism, such position being the same as in the case where the push-pull bar has been manually moved to or held in the on position during overload conditions;

Fig. 19 is a view similar to Fig. 17 with the circuit breaker off and the parts shown in the position assumed after the overload release has functioned; and

Fig. 20 is an exploded view of the slider and trigger mechanism constituting part of the overload release mechanism.

Referring to the first modification disclosed in Figs. 1 to 5, the switch or circuit breaker is housed and mounted within a base of moulded insulating material. A cover plate 12 provided with a bearing 14 is suitably secured to the base 10 and cooperates with such base in operably supporting the mechanism. A pushpull bar or manually movable member 16 has an outer end extending through the bearing 14 and provided with a knob 18 by which the bar may be manually moved inwardly to on position or outwardly to oi position. The inner end 20 of such bar is guided in a bearing 22 provided by the base 10.

A single throw snap action switch is operated by the reciprocal movement of the push-pull bar 16. A ixed contact 24 for such switch is secured within the base 10 as shown and is electrically connected to an external terminal 26. A movable contactor 28 for such switch has spaced pivots 30 at its inner end resting in a depression 32 formed in a slider 34. An over-center compression spring 36 has its outer end engaged by a lug 38 on such movable contactor and its inner end engaged by a lug 40 on such push-pull bar. The spring 36 thus holds the contactor 28 for pivoting action toward and away from the fixed contact 24. When the push-pull bar is in the on position shown in full lines of Fig. l, the over-center spring snaps the contacts closed. When the push-pull bar is pulled outwardly to the off position (shown in broken lines in such figure), the overcenter spring snaps the contactor 28 to the open position also shown in the broken lines of such gure where it rests against an internal abutment 41 formed on the base 10. The lower end of the slider 34 is oifset and has an opening 43 within which the inner end 20 is slidable to permit the push-pull bar 16 to move in normal operation without disturbing the slider 34 while the center spring 36 resiliently holds such slider, the contactor 28, and the push-pull bar 16 in relative operative positions shown in the drawings.

An automatic overload release normally holds the slider 34 inactive and releases such slider to force the push-pull bar to the 01T position when predetermined overload conditions exist. Compression type release springs 42 positioned adjacent the inner end 20 bear against the base 10 and the slider 34 and resiliently urge such slider upwardly to the position shown in Fig. 2. In this position the push-pull bar is in its' off position and the circuit breaker open. However, under normal conditions the slider 34 is latched in the cocked position shown in Fig. 1 by a latch 44 swingable on pins 46 mounted in notches 48 at the upper end of the base 10 and there held bv cover plate 12. The latch is biased toward the slider 34 by a latch spring 50 so that a tooth 52 on the latch will engage the top of a lateral projection 54 on the slider 34. Because of the excessive frictional engagement between the tooth 52 and the projection 54 a current responsive member, operating within close limits of time and current values, cannot be used to directly break such engagement. Hence, there is provided a trigger mechanism which is easily held in cocked position and yet when released will develop suicient force to break open the slider latch. A trigger 56 is normally biased downwardly with respect to the slider 34 by a compression type trigger spring 58 which extends between lateral projections on such slider and trigger, being held in a suitable manner by dimples 60 or the like. The lower end of the trigger has lugs 62 which are guided in grooves 64 in the base 10 and the upper end has a slot 66 which engages the peripheral edge of slider 34 for the purpose of movably guiding these parts. A sloping tooth 68 on the trigger is positioned relative to a sloping tooth 70 on the latch 44 so that when the trigger is uncocked and it snaps toward the lower position shown in Fig. 3, these teeth will engage with sutiicient force to move the latch 44 out of engagement with the slider 34.

The trigger 56 is held in cocked position by a current responsive element 72 such as a bimetal thermal element which normally underlies and engages a lip 74 on the trigger 56. Because the trigger gains some velocity before the

teeth

68 and 70 engage and because of the mechanical advantage derived from the camming action of such teeth, the spring 58 is relatively light in strength and only a small frictional resistance is created between the end of the element 72 and the lip 74. Thus such element will warp away from such lip to uncock the trigger upon a small increase of predetermined current value for a relatively short time. The element 72 is electrically connected to an external terminal 76 and may be adjusted (by mechanism not shown) to control the range of its responsive operation. A pigtail type connector 78 extends from the upper end of the element 72 to the slider 34. It is long enough so as not to interfere with the relative motion between these elements. Thus the flow of current through the circuit breaker passes from the terminal 76 through the bimetallic element to the slider 34 to the contactor 28 to the fixed contact 24 and thence to the terminal 26. As excessive current passes through the element 72 for a predetermined period of time the heat generated will be sufficient to warp such element to the position shown in Fig. 3 thereby uncocking the trigger as described.

It is desirable to prevent the circuit breaker from becoming closed by the manual operation of the pushpull bar when abnormal current conditions cause the element 72 to be warped from latching position. To accomplish this, the trigger 56 is provided with an upper arm terminating in a depending finger 80 which engages the contactor 28 to hold it spaced from the fixed contact 24 whenever the push-pull bar is moved toward on position while the element 72 is out of alinement with the lip 74 as is illustrated by the relationship of the parts shown in Fig. 3. With this arrangement even though the manually operable member 16 be held in on position, the circuit breaker will open if overload conditions arlse.

In order to automatically reset the trigger 56 it is provided with an abutment 82 which normally overlies another abutment 84 on the slider 34. The abutment 84 will strike against the abutment 82 while the slider 34 is moving upwardly by the release springs 42 and carry the trigger 56 to the cocked position with the lip 74 spaced above the top of the element 72, as is shown in Fig. 2.

The operation of this modification of the circuit breaker will now be described. Starting with the circuit breaker closed and the parts shown in the full line position of Fig. l, it is only necessary to manually pull the push-pull bar 16 outwardly to the position shown in the broken line in order to cause the circuit breaker to be opened and the contactor 28 to assume the position shown in the broken line. The over-center spring 36 functions to open and close the contactor 28 with a snap action and to resiliently hold the push-pull bar 16 in either its on or off position. Such normal operation does not disturb the overload release mechanism. With the circuit breaker in the on position, a predetermined overload condition causes the current responsive element 72 to warp out of engagement with the lip 74. The trigger 56 will iirst move downwardly toward the position shown in Fig. 3 moving the contactor 28 out of engagement with the fixed contact 24 and tripping the latch 44. As soon as the latch 44 is tripped, the slider 34 then being uncocked will move upwardly to the position shown in Fig. 2. This forces the push-pull bar 16 to oit position and at the same time resets the trigger 56 with respect to the element 72. Provided the element 72 has warped back to normal, the next time the push-pull bar is moved to on position, the slider 34 will be carried to its cocked position and automatically latched. If the element 72 is not back to normal position, the trigger 56 will not be engaged thereby. As a result, the linger 80 will hold the contactor 28 out of engagement even in the on position of the bar.

Referring to the second modification disclosed in Figs. 6 to l0, the switch or circuit breaker is housed and mounted within a base of moulded insulating mate-- rial. A cover plate 112 provided with a bearing 114 is suitably secured to the base 110 and cooperates with such base in operably supporting the mechanism. A push-pull bar or manually movable member 116 has an outer end extending through the bearing 114 and provided with a knob 118 by which the bar may be manually moved inwardly to on position or outwardly to off position. The inner end 120 of such bar is guided in a bearing 122 provided by the base 110.

A single throw snap action switch is operated by the reciprocal movement of the push-pull bar 116. A fixed contact 124 for such switch is secured within the base 110 as shown and is electrically connected to an external terminal 126. A movable contactor 128 for such switch has a fulcrum 130 at its inner end resting in a depression 132 formed in a plate 133. An over-center compression spring 136 has its outer end engaged by a lug 138 on such movable contactor and its inner end engaged by a lug 140 on such push-pull bar. The spring 136 thus holds the contactor 128 for pivoting action toward and away from the fixed contact 124. When the push-pull bar is in the on position shown in the full lines of Fig. 6, the overcenter spring snaps the contacts closed. When the pushpull bar is pulled outwardly to the oft position (shown in broken line in such figure), the over-center spring snaps the contactor 128 to the open position also shown in the broken lines of such figure where it rests against an internal abutment 141 formed on the base 110.

An automatic overload release normally held in inactive position is effective upon its release to force the pushpull bar to its off position. One of the elements of this automatic overload release is a slider 134 having its lower end offset and provided with an opening 143 within which the inner end 120 of the push-pull bar is slidable to effectively guide the lower end of such slider. Compression-type release springs 142 positioned on opposite sides of the inner end 120 bear against the base 110 and the offset end of the slider 134 and resiliently urge such slider upwardly to the position shown in Fig. 8. In this position the push-pull bar is in its off position and the circuit breaker open. The upper end of the slider has a cross bar 144 the ends of which slidably engage the inner surfaces of the side walls of the base 110 to laterally guide the upper end of the slider. Under normal operating conditions the slider 134 is latched in the cocked position shown in Fig. 6 by the engagement of a tooth 154 on the slider with an internal edge 152 on the plate 133. The tooth 154 is resiliently urged toward the plate 133 by the action of the compression springs 142 in cooperation with a fulcrum 146 on the lower end of the bar 116. Because of the excessive frictional engagement between the tooth 154 and the edge 152 a current responsive member, operating within close limits of time and current values, cannot be used to directly break such engagement. Hence, there is provided a trigger mechanism which is easily held in cocked position and yet when released will v develop sufficient force to break open such latching engagement. A trigger 156 pivotally mounted within the base 110 by pins 160 held at the bottom of grooves 164 is normally biased downwardly by a compression type trigger spring 158 operable between a spring seat 162 on the trigger and the cover plate 112. The trigger 156 has a notch 166 for accommodating the slider 134. The right-hand edge of this notch forms a striker 168 which engages with a downwardly sloping surface of a tooth 170 on the slider 134 to cam the upper end of such slider away from the plate 133 and disengage the latching engagement between the slider and such plate whenever the trigger is uncocked or released from its cocked position.

The trigger 156 is held in its cocked position by a current responsive element 172 such as a bimetallic thermal element, the upper end of which normally underlies and engages a lip 174 on the trigger 156. Because of the velocity gained by the trigger, after it is uncocked and before the striker 168 engages the tooth 170, and because of the mechanical advantage derived from the camming action between such striker and tooth, the spring 158 is made relatively light in strength and only a small frctional resistance is created between the end of the element 172 and the lip 174. Thus such current responsive element will warp away from such lip to uncock the trigger upon a small increase of predetermined current value for a relatively short time. The element 172 is electrically connected to an external terminal 176 and may be adjusted (by mechanism not shown) to control the range of its responsive operation. A pigtail type connector 178 extends from the upper end of the element 172 to the plate 133 and is long enough so as not to interfere with the relative movement of such parts. Thus the flow of current through the circuit breaker passes from the terminal 176 through the bimetallic element to the plate 133 to the contactor 128 to the fixed contact 124 and thence to the terminal 126. As excessive current passes through the element 172 for a predetermined period of time the excess heat generated will be sufficient to warp such element to the position shown in Fig. 7 thereby uncocking the trigger as described.

It is desirable to prevent the circuit breaker from being closed by the manual operation of the push-pull bar when overload current conditions cause the element 172 to be warped from latching position. To accomplish this the trigger 156 is provided with a depending finger 180 which engages a raised knob 181 on the contactor 128 to hold the latter spaced from the fixed contact 124 whenever the push-pull bar is moved toward or held in on position while the element 172 is out of alinement with the lip 174 as illustrated by the relationship of the parts shown in Fig. 7. With this arrangement even though the manually operable member 116 be held in on position, the circuit breaker will open if overload conditions arise.

In order to automatically reset the trigger 156 the pushpull bar 116 is provided with an abutment 182 which will engage the underside of the trigger 156 as the pushpull bar is being moved upwardly by the release springs 142 after the slider 134 has been unlatched. The force of springs 142 is sufficient to overcome the force in spring 158 and hence the trigger 156 is automatically reset in position as shown in Fig. 8 where it will be held on the subsequent downward movement of the bar 116 provided normal operating conditions exist.

The operation of this modification of the circuit breaker will now be described. Starting with the circuit breaker closed and the parts shown in the full line position of Fig. 6, it is only necessary to manually pull the push-pull bar 116 outwardly to the position shown in the broken line in order to cause the circuit breaker to be opened and the contactor 128 to assume the position shown in the broken line. The over-center spring 136 functions to open and close the contactor 128 with a snap action and to resiliently hold the push-pull bar 116 in either its on or off position. Such normal operation does not disturb the overload release mechanism. With the circuit breaker in the on position, a predetermined overload condition causes the current-responsive element 172 to warp out of engagement with the lip 174. The trigger 156 will first move downwardly toward the position shown in Fig. 7 moving the contactor 128 out of engagement with the fixed contact 124 and unlatching the slider 134. As soon as the slider is unlatched it will move upwardly to the position shown in Fig. 8. This forces the push-pull bar 116 to oli position and at the same time resets the trigger 156 with respect to the element 172. Provided the element 172 has warped back to normal, the next time the push-pull bar is moved to on position, the slider 134 will be carried to its cocked position and automatically latched. If the element 172 is not back to normal position the trigger 156 will not be engaged thereby. As a result, the finger 180 will hold the contactor 128 out of engagement with the fixed contact 124 even in the on position of the bar.

Referring to the third modification disclosed in Figs. 11 to 16, the switch or circuit breaker is housed and mounted within a base 210 of moulded insulating material. A cover plate 212 provided with a bearing 214 is suitably secured to the base 210 and cooperates with such base in operably supporting the mechanism. A push-pull bar or manually movable member 216 has an outer end extending through the bearing 214 and provided with a knob 218 by which the bar may be manually moved inwardly to on position or outwardly to off position. The inner end 220 of such bar is guided in a bearing 222 provided by the base 210.

A single throw snap action switch is operated by the reciprocal movement of the push-pull bar 216. A fixed contact 224 for such switch is secured within the base 210 as shown and is electrically connected to an external terminal 226. A movable contactor 228 for such switch has spaced fulcrums 230 at its right-hand end pivotally resting in a depression 232 formed in a fixed plate 233. An over-center compression spring 236 has its left end engaged by a lug 238 on such movable contactor and its right end engaged by a lug 240 on such push-pull bar. The spring 236 thus holds the contactor 228 for pivoting action toward and away from the fixed contact 224. When the push-pull bar is in the on position shown in the full lines of Fig. 11, the over-center spring snaps the contacts closed. When the push-pull bar is pulled outwardly to the off position (shown in broken line in such figure), the over-center spring snaps the contactor 228 to the open position also shown in the broken lines of such figure where it rests against an internal abutment 241 formed on the base 210.

An automatic overload release normally held in inactive position is effective upon its release to force the push-pull bar to its ott position. One of the elements of this automatic overload release is a slider 234 having its lower end offset and provided with an opening 243 within which the inner end 220 of the push-pull bar is slidable. Such lower end also has lugs 245 which are slidably mounted in grooves 247 in the walls of the base 210. The top of such slider has a cross bar 244, the ends of which are slidably guided in a groove 246 also formed in the interior of such base. By this means the slider is restrained to rectilinear motion relative to the base 210 and the push-pull bar 216. Compression-type release springs 242 positioned on opposite sides of the inner end 220 bear against the base 210 and the slider 234 and resiliently urge such slider upwardly to the off position of Fig. 12. Under normal operating conditions the slider 234 is latched in the cocked position shown in Fig. l1 by the engagement of a tooth 254 on the slider with an edge 252 on a bolt 255. This bolt has one end slidably mounted in a slot 257 in the plate 233 and its other end carried by a spring-biased trigger so that such edge may be moved into and out of locking alinement with the tooth 254. Because of the excessive frictional engagement between the tooth 254 and the edge 252, a current responsive member, operating within close limits of time and current values, cannot be used to directly break such engagement. Hence there is provided a trigger mechanism which is easily held in cocked position and yet when released will develop sutiicient power to break open such latching engagement. A trigger 256 pivotally mounted within the base 210 by pins 260 resting at the bottom of grooves 264 is normally biased downwardly by i a compression type trigger spring 258 operable between the cover plate 212 and a spring seat 262 on the bolt 255. The bolt 255 has a fulcrum edge 265 pivotally supported in a depression 267 formed in the trigger 256 and held there by the action of such trigger spring. trigger pivots clockwise about the axes of the pins 260, the bolt 255 will be moved to the left and drawn away from the slider 234. When the trigger is moved in a counter-clockwise direction about such axes, the bolt 255 will be moved to the right toward the slider 234. By this means the edge 252 is brought into and out of latching alinement with the tooth 254. By reason of the sloping wall of the depression 267, the bolt 255 may be forcibly moved with respect to such trigger a sufficient distance to permit the bolt to slide up the sloping surface of the tooth 254 during resetting of the trigger. The mechanical advantage derived from this trigger and bolt arrangement is sufficient to readily break the frictional engagement between the edge 252 and tooth 254 under the power supplied by the relatively low strength compression spring 258.

The trigger 256 is held in cocked position by a current responsive element 272, such as a bimetallic thermal element, the upper end of which normally underlies and engages a lip 274 on the trigger 256. A small increase of predetermined current value for a relatively short time will cause such element to warp away from such lip and uncock the trigger 256. The element 272 is electrically connected to an external terminal 276 and may be adjusted (by mechanism not shown) to control the range of its responsive operation. A pigtail type connector 278 extends from the upper end of the element 272 to the plate 233 and is long enough so as not to interfere with the relative movement of such parts. Thus the flow of current through the circuit breaker passes from the terminal 276 through the bimetallic element to the plate 233 to the contactor 228 to the iixed contact 224 and thence to the terminal 226. As excessive current passes through the element 272 for a predetermined period of time the heat generated will be sufficient to warp such element to When the the position shown in Fig. 13 thereby uncocking the trigger as described.

lt is desirable to prevent the circuit breaker from being closed by manual operation when overload conditions exist. To accomplish this, the contactor 228 is provided with a raised knob 281 which is engaged by the trigger 256 whenever such trigger is uncooked to hold the contactor 228 out of engagement with the tixed contact 224 even though the push-pull bar be moved toward or held in the on position as is illustrated by the relationship of the parts shown in Fig. 13. With this arrangement the circuit breaker will open when overload conditions arise even though the manually operable member 216 be held in on position at the time.

In order to automatically reset the trigger 256, the push-pull bar 216 is provided with an abutment 282 which will engage the underside of the trigger 256 as the pushpull bar is being moved upwardly by the release springs 242 after the slider 234 has been unlatched. The force of springs 242 is suiiicient to overcome the force in spring 258 in the accomplishment of this function. With the trigger so reset, the slider 234 will be latched as the bar is again moved lto on position.

The operation of this modification of the circuit breaker will now be described. Starting with the circuit breaker closed and the parts shown in the full line posiiton of Fig. l1, it is only necessary to manually pull the push-pull bar 216 outwardly to the position shown in the broken line in order to cause the circuit breaker to be opened and the contactor 228 to assume the position shown in the broken line. The over-center spring 236 functions to open and close the contactor 228 with a snap action and to resiliently hold the push-pull bar 216 in either its on or ott position. Such normal operation does not disturb the overload release mechanism. With the circuit breaker in the on position a predetermined overload condition causes the current responsive element 272 to warp out of engagement with the lip 274. The trigger 256 will iirst move downwardly toward the position shown in Fig. 13 moving the contactor 228 out of engagement with the lixed contact 224 and unlatching the slider 234 by withdrawing the bolt 255 so that the edge 252 is withdrawn from the tooth 254. As soon as the slider is unlatched it will move upwardly to the position shown in Fig. l2. This forces the push-pull bar 216 to oli position and at the same time resets the trigger 256 with respect to the element 272. Provided the element 272 has warped back to normal, the next time the push-pull bar .1s moved to on position, the slider 234 will be carried to its cocked position and automatically latched. lf the element 272 is not back to normal position, the trigger 256 will not be engaged thereby and as a result will hold the contactor 228 out of engagement with the fixed contact 224 even in the on position of the bar.

Referrmg to the fourth modification disclosed in Figs. l7 to 20, the switch or circuit breaker is housed and mounted within a base 310 of moulded insulating material. A covcr plate 312 provided with a bearing 314 is suitably secured to such base and cooperates therewith iny supporting the mechanism. A push-pull bar or manually movable member 316 has an outer end extending through the bearing 314 and provided with a knob 318 by which s uch bar may be manually moved inwardly to on position or pulled outwardly to oft position (shown in broken lines in Fig. 17). For the purpose of guiding it, the inner end of such bar is provided with lugs 320 slidble in grooves 322 formed in the inner walls of such ase.

A single-throw snap action switch is operated by the reciprocal movement of the push-pull bar 316. A plate 324 with a fixed contact for such switch is held in grooves in such base. A movable contactor 323 is pivotally mounted on a bracket 331 by projections 330 loosely fitting in openings 332 in such contactor. Such bracket is electrically connected to an external terminal 326. The push-pull bar 316 carries a laterally projecting barrel 338 within which is mounted a compression spring 336 for urging a round-headed pin 349 into sliding engagement with thc surface of the movable contactor 328. The pin 34) performs the double function of holding the contactor 328 in operating relationship and snapping the contactor to on or off positons (see broken lines of Fig. 17) as such rounded head passes the fulcrum point in its travel.

An automatic overload release normally held in inactive or cocked position is efrective upon its release to force the push-pull bar 316 to its oft position. One element of such release is a slider 334 having a lower offset underlying and engaging the bottom of the push-pull bar 316. Such oifset is provided with lugs 345 which are slidably guided in the grooves 322. A compression-type release spring 342 normally urges the slider 334 upwardly with sufficient force to carry the push-pull bar 316 to its off position as shown in Fig. 19. Under normal operating conditions the slider 334 is latched in the cocked position shown in Fig. 17 by the engagement of the upper end thereof with a lip 344 on a pivoted trigger 356. The trigger 356 is pivoted by a shaft 360 to the plate 324 and is resiliently urged in a clockwise direction by a coil-type trigger spring 358 encircling such shaft. In normal conditions the trigger is held in cocked position by a current responsive element 372, such as a bimetallic thermal element, the upper end of which underlies and engages a lip 374 on the right end of the trigger 356. Because the upper end of the slider 334 engages the lip 344 irnmediately adjacent the shaft 360, the moment of force created by the compression in release spring 342 and tending lto turn the trigger in a clockwise direction is relatively small. In opposition to this, the engagement between the current responsive member 372 and the lip 374 is spaced a considerable distance from and on the opposite side of the shaft 360. Thus the moment of force ltending to resist the clockwise rotation of the trigger under inuence of both

springs

342 and 358 is created by a relatively small force acting on a relatively long lever arm. Hence the frictional engagement at such point is so small that upon little increase of predetermined current values for a short time |the current responsive element will warp away from the trigger and permit it to uncock. The element 372 is electrically connected to an external terminal 376 and may be adjusted (by mechanism not shown) to control the range of its responsive operation. A pigtail type connector 378 extends from the upper part of the element 372 to the plate 324 and is long enough so as not to interfere with the relative movement of such element. Thus the iow of current through the circuit breaker passes from the terminal 276 through the bimetallic element 372 to the plate 324 to the movable contactor 328 to the bracket 331 and hence to the external terminal 326. As excessive current passes through the element 372 for a predetermined period of time the heat generated will be suiiicient to warp such element to the position shown in full line in Fig. 18 thereby uncocking the trigger as described.

It is desirable to prevent the circuit breaker from being closed by manual operation when overload conditions exist. To accomplish this the trigger 356 is provided with a linger 380 which engages a projection 381 on the movable contactor 328 to hold such contactor out of engagement with the iixed contact whenever such trigger is released from engagement with the current responsive element 372. The force in trigger spring 358 is suflicient to overcome the force in spring 336 and hold said contactor open even though the push-pull bar 316 be in its on position as is illustrated in Fig. 18. With this arrangement the circuit breaker will open when overload conditions arise even though the push-pull bar 316 be then held in on position.

In order to automatically reset the trigger 356, the push-pull bar 316 is provided with an abutment 382 which will engage a semi-circular projection 384 on the underside of the trigger 356 as the push-pull bar is moved upwardly by the release spring 342 after the slider 334 has been unlatched. The force of spring 342 is suiiicient to overcome the force in trigger spring 358 and any sliding friction between the end of lip 374 and the side of element 372 in the accomplishment of this function. Under normal conditions the element 372 will underlie the lip 374 upon reset. The angle of the lower offset of the slider 334 is such that spring 342 acts to resiliently urge the upper end toward the right into sliding engagement with the end of lip 344. Hence the upper end of the slider 334 will snap under the lip 344 as the push-pull bar 316 is moved to on position from the off position of Fig. 19 to again lock the slider 334 in cocked position.

The operation of this modification of the circuit breaker will now be described. Starting with the circuit breaker closed and the parts shown in the full line position of Fig. 17, it is only necessary to manually pull the pushpull bar 316 upwardly to the position shown in the broken line in order to cause the circuit breaker to be opened and the movable contactor 328 to assume the position shown in the broken line. The spring 336 functions to open and close the contactor 328 with a snap action as the end of such pin passes the fulcrum point of such contactor. Because of the slope of the contactor to the vertical in both on and ott positions the pin 340 under pressure of spring 336 will also resiliently hold the push-pull bar 316 in either its on or off position. Such normal operation does not disturb the overload release mechanism. With the circuit breaker in the on position, a predetermined overload condition causes the current responsive element 372 to warp out of engagement with the lip 374. The trigger 356 will iirst move clockwise toward the position shown in Fig. 18 moving the contactor 328 out of engagement with the fixed contact 324 and unlatching the slider 334 by tipping the lip 344 upwardly. As soon as the slider is unlatched it will move upwardly to the position shown in Fig. 19. This forces the push-pull bar 326 to oif position and at the same time resets the trigger 356 with respect to the element 372. Provided the element 372 has warped back to normal, the next time the push-pull bar is moved to on position the slider 334 will be carried to its cocked position and automatically latched. If the element 372 is not back to normal position the trigger 356 will not become cocked and as a result will swing clockwise as the bar 316 is pushed downwardly and the finger 380 will engage the knob 381 to hold the contactor 328 out of engagement with fixed contact 324 before the pin 340 reaches the fulcrum point of such contactor. As previously explained, even after the pin 340 passes below such fulcrum the trigger so released will still hold the contacts disengaged.

Although only several embodiments of the invention are shown and described herein, it will be understood that this application is intended to cover such other changes or modifications as come within the spirit of the invention or scope of the following claims.

I claim:

1. In an on and ol snap action push-pull operated switch, overload responsive means comprising spring means loaded by a push-pull bar as said bar is moved lnto on position, means for locking said last mentioned means when so loaded, a spring-biased trigger normally urged to unlatched position to unlock said means, and an element normally engaging said trigger in latched position and effective in response to currents of predetermined values to effect unlatching of said trigger, said engagement of the element and the trigger being effected as said bar is moved into on position.

.2. In a switch as claimed in claim l, an abutment on said trigger operable in unlatched position of said trigger to prevent said switch from being placed in on position by said push-pull bar.

3. A free-tripping overload switch comprising relatively movable engageable contacts, a manually movable member supported for movement relative to said contacts to and from off and on positions, resilient means operable between said member and one of said contacts to urge said contacts into engagement when said member is in on position and to urge said contacts out of engagement when said member is in olf position, anA overload release spring operative when released to force said member to olf position, said spring being loaded as said member is moved to on position, means for locking said spring in loaded condition in a position permitting said member to move to and from oli and on positions without actuation of said spring, and trigger mechanism including a current responsive element for tripping said means.

4. A switch as claimed in claim 3, in which said trigger mechanism has an abutment holding said contacts disengaged in the sprung condition of said trigger mechanism.

5. A switch as claimed in claim 3, in which said means for locking comprises: a slider having a portion interposed between said overload release spring and said manually movable member and a latch portion; and a latch plate with which said latch portion engages to hold said slider with said spring so loaded.

6. A switch as claimed in claim 5, in which said slider has an abutment to engage said trigger mechanism in the sprung condition of said overload release spring to reset said trigger mechanism with respect to said current responsive element.

7. A snap action circuit breaker having a manually operable member reciprocatably movable to and from on and off positions, means including spring means operable by said member to operate said circuit breaker in each direction with a snap action under normal conditions, automatic means released from a cocked position under overload conditions to open said circuit breaker and move said member to oit position, and second means for cocking said automatic means as said mernber is moved to on position after previous release of said automatic means.

8. A snap action circuit breaker having a manually operable member movable to and from on and off positions to operate said circuit breaker under normal conditions, automatic means released from a cocked position under overload conditions to open said circuit breaker and move said member to oit position, and second means for cocking said automatic means as said member is moved to on position after previous release of said automatic means, said automatic means comprising a spring-biased slider operable when released to move said member to off position, a latch for holding said slider in cocked position, a slider-charged trigger operable when released from charged position to open said circuit breaker and trip said latch, and a current responsive element subject to overload conditions and normally biased to hold said trigger in charged position.

9. A free-tripping overload switch comprising in combination an element rectilinearly movable to on and oft positions and being biased in one direction, an overload release spring operative when released to force said element to oil position, said spring being loaded as said element is moved to on position, cooperating contacts including a contactor pivotally supported on said element, a latch biased into engagement with said element to restrain said element against the bias of said element, a rectilinearly movable trigger, spring means operable between said trigger and said element to urge said trigger in a direction to disengage said latch, a thermally responsive means normally restraining said trigger against said spring means, operating means for said contactor to resiliently engage and disengage said contacts at will while said element is latched and to relatch said element, and a part on said trigger engageable with said contactor to maintain said contacts disengaged when said thermally responsive means no longer restrains said trigger and while said operating means is in position to engage said contacts.

10. A free-tripping overload switch comprising in combination an element rectilinearly movable to on and olf positions and being biased in two directions, an overload release spring operative when released to force said element to ofi position, said spring being loaded as said element is moved to off position, cooperating contacts including a contactor pivotally supported adjacent said element, a fixed edge adjacent said element, a tooth on said element engageable with said edge under the influence of the bias of said element in one of said directions to latch said element against the bias of said element in the other of said directions, a pivotally mounted trigger biased in one direction and having a striker to engage said element and disengage said tooth and said xed edge, a thermally responsive means normally restraining said trigger against its bias, operating means for said contactor to resiliently engage and disengage said contacts at will while said element is latched and to relatch said element, and a part on said trigger engageable with said contactor to maintain said contacts disengaged when said thermally responsive means no longer restrains said trigger and while said operating means is in position to engage said contacts.

1l. A free-tripping overload switch comprising in combination an element rectilinearly movable to and from off and on positions, an overload release spring operative when released to force said element to off position, means for locking said spring in loaded condition in a position permitting said element to move to and from ott and on positions without actuation of said spring, cooperating contacts including a contactor pivotally supported adjacent said element, a tooth on said element, a bar having longitudinal movement for engagement with said tooth, a pivotally mounted trigger biased in one direction and interconnected with said bar to impart longitudinal movement thereto to cause said bar to disengage from said tooth, a thermally responsive means normally restraining said trigger against its bias, operating means for said contactor to resiliently engage and disengage said contacts at will while said element is latched and to relatch said element, and a part on said contactor engageable by said trigger to maintain said contacts disengaged when said thermally responsive means no longer restrains said trigger and while said operating means is in position to engage said contacts.

l2. In an on and off spring-biased snap action push-pull bar operated switch, relatively movable engageable contacts, a manual push-pull bar supported for movement relative to said contacts to and from off and on positions, resilient means operable between said bar and one of said contacts to urge said contacts into engagement when said bar is in on position and to urge said contacts out of engagement when said bar is in oit position, free-tripping overload protection comprising a slider movable relative to said bar and having a cocked position, a release spring loaded by said slider in the cocked position of said slider and operable to move said bar to olf position when said slider is uncocked, said spring being loaded as said bar is moved to on position, a tooth on said slider, a bolt to engage said tooth and hold said slider in said cocked position, a pivoted member associated with said bolt and biased in one direction to withdraw said bolt from engagement with said tooth, and a current responsive element normally holding said pivoted member in the untripped position thereof.

13. In an on and off spring-biased snap action push-pull bar operated switch, relatively movable engageable contacts, a manually movable push-pull bar supported for movement relative to said contacts to and from off and on positions, resilient means operable between said bar and one of said contacts to urge said contacts into engagement when said bar is in on position and to urge said contacts out of engagement when said bar is in off position, free-tripping overload protection comprising a slider movable relative to said bar and having a cocked position, a release spring loaded by said slider in the cocked position of said slider and operable to move said bar to said off position when said slider is uncocked, said spring being loaded as said bar is moved to on position, a lateral projection on said slider, a pivoted latch spring-biased into engagement with said projection to hold said slider in said cocked position, a slidable member spring-biased from an untripped position in a direction to disengage said latch from said projection, and a current responsive element normally holding said slidable member in the untripped position thereof.

14. In an on and off snap action push-pull bar operated switch, relatively movable engageable contacts, a push-pull bar supported for movement relative to said contacts to and from off and on positions, resilient means operable between said bar and one of said contacts to urge said contacts into engagement when said bar is in on position and to urge said contacts out of engagement when said bar is in oit position, free-tripping overload protection comprising a slider movable relative to said bar and having a cocked position, a release spring loaded by said slider in the cocked position of said slider and operative to move said bar to o position when said slider is uncocked, said release spring being loaded as said bar is moved to on position, a tooth on said slider, a fixed edge engageable by said tooth to hold said slider in said cocked position, a pivoted member springbiased from an untripped position in one direction to contact said slider and disengage said tooth from said edge, and a current responsive element normally holding said pivoted member in the untripped position thereof.

l5. In an on and oit snap action push-pull bar operated switch, overload protection comprising a slider movable relative to said bar and having a cocked position, a release spring loaded by said slider in said cocked position and operable to move said bar to off position when said slider is uncocked, an elongated trigger, a pivot for said trigger close to one end thereof to permit said trigger to swing from a latched to an unlatched position, a rst lip on said trigger at said end to hold said slider in cocked position when said trigger is in latched position, a second lip on the other end of said trigger, and a current responsive element positioned to engage said second lip and hold said trigger in latched position.

16. A free-tripping overload switch comprising in combination a rectilinearly movable member biased in one direction from a cocked position, cooperating contacts including a contactor pivotally mounted intermediate its ends, a latch pivoted intermediate its ends and swingable to and from latched and unlatched positions, said latch having a lip on one side of its pivot engageable with said member in said latched position to restrain said member in said cocked position, a thermally responsive element positioned to engage said latch on the opposite side of its pivotal connection to hold said latch in latched position, and operating means for said contactor including a springbiased pin slidably engageable with said contactor to engage and disengage said contacts at will while said member is cocked and to recock said member.

17. A switch as claimed in claim 16 in which said latch carries a finger adapted to engage said contactor to disengage said contacts when said latch is uncocked, and spring means to urge said latch to said uncocked position with enough force to hold said contacts disengaged independently of the position of said operating means whenever said thermally responsive element is out of engagement with said latch.

18. A switch as claimed in claim 17 in which there is an abutment on said operating means to engage and relatch said latch as said operating means is moved to disengage said contacts under influence of said member.

19. A free-tripping overload switch comprising cooperating contacts including a movable contactor pivoted intermediate its ends, a push-pull bar supported for longitudinal movement between ofi and on positions, a spring-biased pin carried by said bar and resiliently slidably engaged with said movable contactor to engage and disengage said contacts as said bar is moved to and from on and off positions, a slider having a cocked position and movable to an uncocked position to engage and move said bar to ofr' position, a release spring normally urging said slider to said uncocked position, a member having a pivotal mounting, a portion on said member near one side of said pivotal mounting engageable with said slider to hold said slider in said cocked position with said release spring compressed, a thermal-responsive element having an end underlyingly engaging said member on the opposite side of said pivotal mounting at a place spaced from said pivotal mounting a distance in excess of the distance between said portion and said pivotal mounting whereby frictional engagement between said thermalresponsive element and said member caused by the pressure of said release spring is sufficiently low to permit said thermal-responsive element to move out of underlying engagement with said member upon a small change for a short time inthe thermal condition to which said element is subjected.

20. A free-tripping overload switch comprising cooperating contacts including a contactor having a pivotal support intermediate its ends, a push-pull element movable to and from off and on positions, a resiliently biased member carried by said element and slidably engaged with said contactor to engage and disengage said contacts as said element is moved to on and off positions, a release spring for moving said element to oil position, a latch having a cocked position for holding said spring compressed and out of operative engagement with said element, a trigger having a latch-engaging portion operable in the locked position of said trigger to hold said latch in said cocked position, and a current responsive device engageable with said trigger under normal operating conditions to hold said trigger in said locked position and disengageable from said trigger under abnormal operating conditions.

21. A free-tripping overload switch comprising cooperating contacts including a contactor having a pivotal support intermediate its ends, a push-pull element movable to and from off and on positions, a resiliently biased member carried by said element and slidably engaged with said contactor to engage and disengage said contacts as said element is moved to on and off positions, a release spring for moving said element to off position, a latch having a cocked position for holding said spring compressed and out of operative engagement with said element, a trigger having a latch-engaging portion operable in the locked position of said trigger to hold said latch in sald cocked position, a current responsive device engageable with said trigger under normal operating conditions to hold said trigger in said locked position and disengageable from said trigger under abnormal operating conditionsz sprlng means urging said trigger from said locked posltlon to a sprung position, and abutment means between said trigger and said contactor operable in said sprung position to disengage said contacts in either position of said element.

22. free-tripping overload switch comprising cooperating contacts including a contactor having a pivotal support intermediate its ends, a push-pull element movable to and from off and on positions, a resiliently biased member carried by said element and slidably engaged with said contactor to engage and disengage said contacts as said element is moved to on and 01T positions, a release spring for moving said element to off position, a latch having a cocked position for holding said sprmg compressed and out of operative engagement with said element, a trigger having a latch-engaging portion operable in the locked position of said trigger to hold said latch in said cocked position, a current responsive device engageable with said trigger under normal operating conditions to hold said trigger in said locked position and disengageable from said trigger under abnormal operating conditions, spring means urging said trigger from said locked position to a sprung position, abutment means between said trigger and said contactor operable in said sprung position to disengage said contacts in either position of said element, and abutment means between said trigger and said element to reset said trigger in said locked position as said element is moved to off position.

23. A snap action circuit breaker having a manually operable member movable to and from on and off positions to operate said circuit breaker under normal conditions, automatic means released from a cocked position under overload conditions to open said circuit breaker and move said member to off position, said automatic means comprising a spring-biased slider operable when released to move said member to off position, a latch for holding said slider in cocked position, a springcharged trigger operable when released from charged position to open said circuit breaker and trip said latch, a current responsive element subject to overload conditions and normally biased to hold said trigger in charged position, second means for cocking said automatic means as said member is moved to on position after previous release of said automatic means, said second means comprising a first abutment movable with said member as said member is moved toward off position by said slider and a second abutment carried by said trigger and contacted by said first abutment to move said trigger to charged position as said member is moved into off position, and a one way engagement between said member and said slider to move said slider into cocked and latched position when said member is moved to on position.

24. A snap action circuit breaker having a manually operable member movable to and from on and off positions to operate said circuit breaker under normal condition, automatic means released from a cocked position under overload conditions to open said circuit breaker and move said member to off position, second means for cocking said automatic means as said member is moved to on position after previous release of said automatic means, said second means comprising a first abutment movable with said member as said member is moved toward off position by said slider and a second abutment carried by said .trigger and contacted by said first abutment to move said trigger to charged position as said member is moved into off position, and means providing a one way engagement between said member and said slider to move said slider into cocked and latched position when said member is moved to on position.

References Cited in the file of this patent UNITED STATES PATENTS 1,967,122 Horst July 17, 1934 2,233,187 Von Hoorn Feb. 25, 1941 2,381,294 Langstroth Aug. 7, 1945 2,447,137 Runke Aug. 17, 1948 2,485,736 Ingwersen Oct. 25, 1949 2,625,625 Ingwersen Ian. 13, 1953