US2409917A - Circuit breaker - Google Patents

Description

OC- 22, 1946. F. G. voN HOORN CIRCUIT BREAKER Filed Feb. 2e, 1943 H o a/yfmw His Attorney l Inventor:

Pred G. von

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Patented 'Oct 22, 1946 CIRCUIT BREAKER Fred G. von Hoorn, Nichols, Conn., assi'gnor to General Electric Company, a corporation of New York Application February 26, 1943, Serial No. 477,222

(Cl. 20D- 116) 11 Claims. 1

My invention relates to circuit breakers, more particularly to manually operated thermal overload responsive circuit breakers, and has for its object a simple and reliable circuit breaker wherein means is provided for manually holding the circuit breaker in a closed circuit position including switching means which short-circuits the thermal load responsive means.

In carrying out my invention in one form I provide a slidably mounted operating member which is manually operated and which, when moved slidably to a predetermined closed circuit position, is held in that position by a thermal load responsive device. On this operating member is pivotally mounted intermediate its length a contact bar which normally is held by a spring in a predetermined angular position on a carriage. When the manual operating means is moved to its closed position to be held by the thermal device, one end of the bar engages a stationary contact to close a circuit through the thermal device. When the manual operating means is moved Still farther against the force applied by the spring, the other end of the bar engages a second switch contact whereby the thermal device is short-circuited and the switch can, therefore, be heldin this closed circuit position manually forv an indefiniter length of time without damage to the thermal .element from excessive current.

For a more complete understanding of my invention, reference may be had to the accompanying drawing in which Fig. 1 is a View mainly in cross section of a circuit breaker embodying my invention showing the circuit breaker moved manually to its extreme closed circuit position in which the thermal device is short-circuited; Fig. 2 is a View similar to Fig. l but showing the contact bar in its normal closed circuit position; Fig. 3 is a view similar to Fig. 2 but showing the parts after automatic opening in response to an overcurrent; Fig. 4 is a view taken along the line 4 4 of Fig. 1 looking in the direction of the arrows; Fig. 5 is a View taken along the line 5--5 of Fig. 3 looking in the direction of the arrows; while Fig. 6 is an exploded view of parts of the operating mechanism.

Referring to the drawing, I have shown my invention in one form as comprising a carriage or operating member I0 shown substantially as an inverted U-shaped member. This operating member I0 is mounted for slidable movement between the electrically insulating side walls II and I2 of a suitable casing or enclosure for the mechanism. The operating member is moved slidably by means of a cylindrical button I3 secured to it and extending through a suitable aperture in the cover I4 for the casing. As shown clearly in Fig. '6, the button I3 is secured to the upper transverse portion of the operating member, as by a suitable bolt, there being an inverted U-shaped guide member having parallel guiding sides I5 and I6 secured to the operating member with its base clamped between the button I3 and the carriage. The guides I5 'and IB are parallel with the button I3 and they lit loosely in slidable relation in suitable shallow guides extending vertically, as seen in the drawing, in the inner sides of the walls II and I2. This is indicated clearly in the drawing 'in which the guide I6 is shown fitted loosely in the shallow groove I'I in the side wall of the casing.

Thus the operating member I0 can be moved slidably downward by pressing on the button I3,

its left-hand end bearing, as shown in Fig. 3, against an .electrically conducting bearing and latch member I8 secured to a suitable current responsive device, shown asa bimetallic thermostatic strip I9 having its upper end secured as by welding at 20 to an electrically conducting support 2| secured to a side wall of the casing. Thus when the operating member II) is moved downward to the position shown in Fig. 2, the hook shaped latching extension 22 on the left-hand arm of the operating member IEJ is below the member I3 carried by the thermostat, and the thermostat, in accordance with its bias when at a normal ambient temperature, springs toward the right hand at its lower end thereby moving the latch member I8 in latch securing engagement above the hook 22. Because of the fact that the operating member I0 is constrained by the guides I5 and I6 to move slidably in a direction perpendicular to the engaging faces of the latch members I8 and 22, the operating member is thus held by the thermostat, as shown in Fig. 2, against movement in an upward direction.

Mounted on the operating member I0 and extending transversely with respect to the line of movement of the operating member is a current carrying switch member, shown as a bar 23, which is pivoted at a point intermediate its length on the right-hand arm of the operating member so as to be pivotally movable about a pin 24 on this arm, while the left-hand portion of the arm extends downward somewhat and into a slot 25 in the left-hand arm of the operating member, the upper wall 26 of which slot forms a stop for the bar under certain conditions. Thus the pivot 24 and the stop 26 are spaced apart transversely of the line of movement of the operating member. The bar and operating member ID are normally biased upward to an open circuit position, as shown in Fig. 3, by means of a helical spring 21 having its lower end resting on the lower wall 28 of the enclosing casing and its upper end bearing on the lower edge oi the bar 23 at a point between the pivot 24 and stop 26.

'I'he right-hand end of the bar is provided with a movable contact 29 arranged to engage a stationary contact 30 mounted on a stud 3| extending through the lower wall of the casing and provided on the exterior with a screw detachable connection 32 which forms one terminal of the circuit breaker. On its left-hand end the bar 23 carries a second movable contact 33 which, when the button I3 is depressed to its extreme lower position, as shown in Fig. l, engages a second contact surface 34 secured on a contact stud 35 provided with an exterior terminal 33 forming a second terminal for the circuit breaker.

For the purpose of including the thermostat I9 in the circuit of the switch, an electrically conducting strip or strap 31 is provided which is seated in a suitable upright shallow groove 38 provided for it in one wall of the circuit breaker enclosure, the lower end of this strap 31 being bent laterally and secured to the upper end of the stud 35. This strap 31 is provided with a laterally and upwardly extending arm 39 positioned 'I between the inner walls of the enclosure. The upper end of this arm 39 is bent over laterally to form the support 2| for the upper end of the thermostat I9. For the purpose of adjusting the position of this arm 2|, and therefore the position and current response of the thermostat, a screw 4U is provided in the end of the support 2 I, which screw bears on the lateral projection 4| on the upper end of the strap 31, which projection extends toward the observer, as seen in Figs. 1-3 inclusive.

Thus the electric circuit through the circuit breaker can be traced from the terminal 35 through the bar 31 and the arm 33 to the upper end of the thermostat and thence downward L:

through the thermostat to a flexible conductor 42 which has one end secured, as by welding, to the latch member I8 at the point 43 and its other end secured to the bar 23 at the point 44. The circuit then leads from the flexible conductor through the right-hand end portion of the bar 23 and when the circuit breaker is in its closed circuit position, as shown in Fig. 2, through the contacts 29 and 30 to the other terminal 32.

In the operation of the device, assuming that it is in its normal closed circuit position as shown in Fig. 2, upon the occurrence of a current greater than a predetermined value the thermostat I3 is heated by the current passing through it sufficiently to move its lower end toward the left, enough to release the latch 22. The spring 21 thereupon moves the bar 23 and operating member I0, together with the button I3, upward to the open circuit position shown in Fig. 3. In this position the left-hand portion of the bar 23 is forced upward into engagement with the stop 26 formed by the upper wall of the slot 25.

When the thermostat has cooled sufficiently so that it will spring back and secure the operating member, the circuit breaker may be closed again by pushing downward on the button I3, as previously described, whereupon the parts assume the positions shown in Fig. 2. During this downward movement the contact 29 engages the stationary contact 3|) just before the downward movement of the operating member is completed and, as the operating member moves still farther downward to its closed circuit position, the bar pivots counterclockwise about the stationary contact 33 and also pivots counterclockwise about the pin 24 whereby the left-hand end of the bar moves downward with respect to the operating member out of engagement with the stop 26. Thus, as shown in Fig. 2, the spring 21 not only biases the parts upward, but also it biases the left-hand end ol the bar upward about the pivot pin E4 thereby to force downward the right-hand end Contact 29 against the stationary contact 33. This assures a rm engagement between the contacts.

Another feature of my invention is the provision for manually holding the circuit breaker closed despite the releasing tendency of the thermostat I9. This is carried out by pressing the button I3 downward still farther to the position shown in Fig. 1 in which the bar 23 has pivoted counterclockwise about the stationary contact 33 and the pin 24 until its left-hand end has brought the contact 33 downward into engagement with the stationary contact 34. This, it will be observed, entirely short-circuits the thermostat, for the circuit through the circuit breaker now is from the terminal 35 directly to the movable contact 33, thence through the bar 23, contacts 23 and 33 to the other terminal 32. Therefore, no appreciable current flows through the thermostat and it is not heated. Thus the button may be operated to hold the circuit breaker closed after it has been opened automatically by the thermostat, as shown in Fig. 3, in response to a heavy current or it may, ci course, be immediately moved to this second closed position if desired. The short-circuiting of the thermostat is important in that it prevents damage to the thermostat from the very high currents which may flow through the circuit breaker. Of course there would be no object in holding the circuit breaker closed with currents of normal low value which would not cause the thermostat to trip open the circuit breaker.

As shown in Fig. 3, the bar 23 is provided with a V-shaped notch 45 in its upper edge the sides of which embrace the pivot pin 24. As shown, the bar may be secured to the operating member by means of a partially open slot, one side of which is bent outward, the bar put in place in the slot, and then this side is bent back in place so that the lateral projection 4l on its lower end loosely secures the bar. The upward pressure of the spring 21, of course, always holds the bar in a lateral position in which the pivot pin 24 is seated at the bottom of the V notch 45.

While I have shown a particular embodiment ol my invention, it will be understood, of course, that I do not wish to be limited thereto since many modications may be made, and I therefore contemplate by the appended claims to cover any such modications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A circuit breaker comprising an operating member, supporting means for said operating member mounting said operating member for movement in a predetermined direction, a switch member pivotally mounted intermediate its length on said operating member, a stop on said operating member for engagement by a first end of said switch member, a spring bearing on said switch member for biasing the switch member into engagement with said stop and for biasing the switch member and operating member to an open circuit position, a stationary contact in position to be engaged by the other end of said switch member when said Yoperating member is moved toward a predetermined closed circuit position to compress saidy spring and thereafter cause movement of said rst end away from said stop upon. continued movement of said operating member to said predetermined closed circuit po'- sition, and current responsive means for engaging and holding said operating member in said closed circuit position against .the force of said spring.

2. A circuit breaker comprising an operating member, supporting means for said operating member mounting said loperating member for movement in a predetermined direction, a switch member extending across said direction of movement, pivot supporting means on said operating member for pivotally supporting said switch member on said operating member at a point intermediate the ends of said switch member, a stop on said operating member for a rst end of s-aid switch member, said stop being spaced from said pivot transversely of said movement` a spring bearing on said switch member at a point between said pivot and said stop for biasing said switch member into engagement with said stop and for biasing said switch member and operating member to an open circuit posi-tion, a stationary contact in position to be engaged by the other end of said switch member when said operating member is moved toward a predetermined closed circuit position to compress said spring, said switch member thereafter upon continued movement of said operating member to said closed circuit position pivoting on said contact and said pivot so that said rst end is moved away from said stop against the force applied by said spring, and means for engaging and holding said operating member in said closed circuit posi-tion against the force of said spring.

3. A circuit breaker comprising a slidably mounted. operating member, a switch member mounted on said operating member, a pair of stationary contacts, said switch member being movable by said operating member into engagement with said stationary contacts, means for biasing said switch member and said operating member to an open circuit position, current responsive means for holding said operating member in an intermediate position in which one end only of said switch member is held by said biasing means in engagement with one of said stationary contacts, and connections for including said current responsive means in an electric circuit between said stationary contacts when said operating member is in said intermediate position.

4. A circuit breaker comprising a slidably mounted operating member, a switch member pivotally mounted on said operating member at a point intermediate its length, a pair of station- -ary contacts, said switch member being movable by said operating member into engagement with said stationary contacts, a spring bearing on said switch member for biasing said switch member to a predetermined position with respect to said operating member and said switch member and said operating member to an open circuit position, and current responsive means for holding said operating member in an intermediate posi- ,tion in which only one end of said switch member is held by said spring in engagement with one of said stationary contacts, and connections for including said current responsive means in an 6 electric circuit between said stationary contacts when said operating member is in said intermediate position. l

5. A circuit breaker comprising an operating member, supporting means for said operating member `mounting said operating member for movement in a predetermined direction, a switch member pivotally mounted intermediate its ends on said operating member, a stop on said operating member for engagement by a iirst end of said switch member, .a spring bearing on said switch member for biasing said switch member into engagement with said stop and for biasing said switch member and operating member to an open circuit position, a stationary contact in position to be engaged by the other end of said switch member when said ope-rating member is moved to compress said spring and thereafter cause movement of Said rst end away from said stop upon continued movement of said operating member to a predetermined closed circuit position, thermal current responsive means for releasably holding said operating member in said closed circuit position, and a second stationary contact engaged by said first end of said switch member when said operating member is moved in a circuit closing ldirection beyond said closed circuit position whereby said switch member establishes a circuit between said stationary contacts independent of said thermal device,

6. A circuit breaker comprising an operating member, supporting means mounting said operating member for sliding movement in a predetermined direction, a switch bar pivotally mounted at an intermediate point thereof on said operating member, a stop on said operating member for a iirst end of said bar, a movable electric contact on the other end of said bar, a spring bearing on said bar at a point between said intermediate point and said rst end of said bar applying a force to said bar in a direction to hold said iirst end of said bar against said stop and to bias said bar and operating member to a predetermined open circuit position, manual means for slidably moving said operating member and bar to other positions against the force applied by said spring, a stationary contact on said support in position to be engaged by said contact on said bar when said bar is moved manually against the force of said spring to a predetermined position whereupon said bar pivots on said operating member upon continued movement of said operating member, current responsive means for engaging said operating member upon such continued movement of said operating member thereby to hold said operating member in a predetermined position when said manual operating means is released whereby said contact is held by said spring in engagement with said stationary contact.

'7. A circuit breaker comprising an operating member, supporting means mounting said operating member for sliding movement in a predetermined direction, a switch bar pivotally mounted at an intermediate point of said bar on said operating member, a stop on said operating member for a rst end of said bar, movable rst and second electric contacts on said first and the second ends of said bar, a spring bearing on said bar at a point between said intermediate point and said first end of said bar applying a force to said bar in a direction to hold said first end of said bar against said stop and to bias said bar and operating member to a predetermined open circuit position, manual means for slidably moving said operating member and bar to other positions against the force applied by said spring, a stationary contact on said support in position to be engaged by said second contact on said bar when said bar is moved manually to a predetermined position whereupon said bar pivots on said operating member upon continued movement of said operating member, current responsive means for engaging said operating member upon such continued movement of said operating member thereby to hold said operating member in a predetermined position when said manual operating means is released whereby said second contact is held in engagement with said stationary contact, and a second stationary contact on said support in position to be engaged by said rst contact when said manual means is moved still further whereby said bar forms an electrical connection between said stationary contacts.

8. A circuit breaker comprising an inverted U-shaped operating membery a support mounting said operating member for sliding movement in a direction substantially parallel with its legs, a first leg of said U-shaped member being extended and provided with a slot, a switch bar pivotally mounted at an intermediate point of said bar on the end of the second of said legs and having a first end extending into said slot, movable first and second electric contacts on said iirst and the second ends of said bar, a spring bearing on said bar at a. point between the legs of said U-shaped member and applying a force to said bar in a direction to hold said first end of said bar against the upper wall of said slot and to bias said bar and U-shaped member to a predetermined open circuit position, manual means for slidably moving said U-shaped member and bar to other positions against the force applied by said spring, a stationary contact on said support in position to be engaged by said second contact on said bar when said bar has been moved manually to a predetermined position whereupon said bar pivots on said other leg of said U-shaped member upon continued movement of said U-shaped member, current responsive latching means for engaging the end of said extended leg upon such continued movement of said U-shaped member thereby to hold said U-shaped member in a predetermined position when said manual operating means is released whereby said second movable contact is held in engagement with said stationary contact, and a second stationary contact on said support in position to be engaged by said first movable contact when said manual means is depressed still further whereby said bar forms an electrical connection between said stationary contacts.

9. A circuit breaker comprising a pair of stationary contacts, movably mounted switch contact means, means biasing said switch contact means in disengaged relation with said stationary contacts, said switch contact means being movable into engagement with said stationary contacts to form a circuit between them, current responsive means for holding said switch contact means in a predetermined position in engagement with only one of said stationary contacts, and electric connections including said current responsive means in an electriccircuit through said switch contact means.

10. A circuit breaker comprising a movably mounted operating member, means biasing said operating member to a predetermined position, a pair of stationary contacts, switch contact means actuated by said operating member normally in disengaged relation with said stationary contacts but movable into engagement with said contacts to form a circuit between them by movement of said operating member against its bias to a predetermined second position, current responsive means for holding said switch contact means in a third position in engagement with one of said stationary contacts, and electiic connections including said current responsive means in an electric circuit through said switch contact means.

il. A circuit breaker comprising a movably mounted operating member, means biasing said operating member to a first predetermined position, switch contact means mounted on said operating member, a pair of stationary contacts, said operating member being movable to a second predetermined position against its bias to bring said switch contact means into engagement with only one of said stationary contacts, current responsive means ior holding said operating member in said second predetermined position with said switch contact means in engagement with said one of said stationary contacts, connections for including said current responsive means in an electric circuit through said switch contact means, and additional switch contact means carried by said operating member and electrically connected to said rst switch contact means for engaging both oi said stationary contacts when said operating member is moved to a third predetermined position thereby to establish an electric connection between said stationary contacts independent of said current responsive means.

FRED G. voN HOORN.

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