US2371738A - Electric switch and switch operating mechanism - Google Patents

Description

c. A. cHRlsTol-'FERsoN ELECTRIC SWITCH AND SWITCH' OPEHATIG MECHAISM Filed June s, 1942 March z; 1945.

hailed Mar. 2o, 194s UNITED STATE s PATENT OFFICE ELECTRIC SWITCH AND SWITCH OPERATING MECHANISM Carl A. Christofferson, Acton, Mass., assigner to The Chase-Shawmut Company, Newburyport, Mass., a corporation of Massachusetts Application June 8, 1942, Serial No. 446,170 10 Claims. (Cl. 20G-1 1@ type wherein the breaker will open in response to abnormal current conditions but when desired may be maintained manually in circuit closed position even though the abnormal current condition persists.

There is need for a small combined switch and circuit breaker that can be opened and closed manually, that can open automatically in response to overload in the circuit and that can be maintained closed in spite of the overload, at least for a period of time sufiicient for the overloaded circuit to accomplish its intended purpose.

Such a circuit control and protective device and the operating mechanism for the circuit-controlling contacts constitutes an object of this invention.

A further object of the invention is the provision of a switch and circuit breaker as above set forth wherein the circuit is closed and also opened rapidly, as with a snap action, by the use of an over-center spring.

Another object of the invention is the provision of an improved switch and circuit breaker, and the operating mechanism for the circuitcontrolling contacts thereof, wherein the contacts are caused to separate in response to an overloadl and the mechanism is reset and the contacts restored'into engagement by movement of the operating handle from a position corresponding to the open position of the circuit to a position corresponding to the closed position of the circuit.

A yet furtherobject ,of the invention is the `provision of Yan improved switch and circuit breaker wherein the operating handle is sup'- ported by a swinging member normally held from 'swinging by currentresponsive means and, when released, swings in a manner to effect its own movement and movement of the movable contact member f the switch into positions corresponding to open circuit positions, the mechanism being so arranged that such movement is prevented when the handle is held manually in its closed circuit position, and the swinging lever being reset and the circuit being reclosed by manual movement of the handle into itsr closed-circuit position.V

handle therefor is moved into circuit closed position and will remain reset even though the overload current condition persists as long as the handle is held in circuit closed position. To this end, and as illustrated, the current responsive mechanism for operating the deviceV automatically upon the occurrence of an abnormal current. condition is biased from an operative position into an inoperative position by the same means which biases the movable contact member ,or switch arm into'respective circuit open and circuit closed positions.

Another object of the invention is to improve generally upon the construction and operation of combined switches and circuit breakers.

With the above and other objects and features in view the invention will now be described with reference to the accompanying drawing in which w Fig. 1 is a vertical cross-sectional view of a switch and circuit breaker embodying the present invention and showing the parts in circuit closed position;

Fig. 2 is a view similar to Fig. 1 but showing the parts in manual open circuit position;

Fig. 3 is a view similar to Fig. l but showing the parts in automatic open circuit position;

'Fig 4 is a View in cross section taken along the line 4-4 of Fig. 3; and

Fig. 5 is a View incross section taken along the line 5-5 of Fig. 3.

The switch and circuit breaker illustrated in Y the drawing is of relatively small dimensions and is herein shown on an enlarged scale to approxivmately twice size. A small size breaker is desirable for many purposes, as in aircraft, for instance, but it is apparent that the circuit breaker may be made in other sizes, larger or smaller, if Vso desired.

The illustrated circuit breaker is arranged to be enclosed within a casing lli which preferably v is formed of one piece of molded plastic material such, for example, as Bakelite. 'I'he top of the casing l0 is provided with 'an opening l2 for receiving the manually operated handle il of the breaker. The bottom of the casing l0 is open so that the entire breaker assembly including the operating handle Il may be inserted into the casing l0 in which it is held in position Yby pins I5 extending through the walls of the casing I0 and through the frame of the breaker assembly. Other holding means may, of course be employed if so desired.

The breaker mechanism is supported on and between twoV sheets i6, I8 of suitable insulating material such, for example, as vulcanized fibre,

. terial. The terminal 2b is wide enough to eX- tend between the supporting sheets l d and i8 and is provided ateither side with ears 28 which extend through openings in the sheets it, i8 and embedded in the openings and support the terminal 2D in ixed position andalso rigidly connect the sheets. The upper end of the terminal 2li is provided with a suitable contact member 313 which cooperates in circuit closed position with a movable contact member 32' :dxed to the lower end. of a two part pivoted switch arm Bil which in turn is pivoted at its upper end to the supporting sheets IB, i8 by outwardly extending p studs 3E iixed to or formed as a part of the upper 'ends of the legs of the switch arm Bil.

The switch arm 3d is moved intov and out ci circuit open position yby a pair of over-center rattrap springs 3B which are secured at their lower ends to a pin d@ extending through the lower ends of the legs of 1the switch arm 3G. The upper ends oi the springs 38 are secured to a pin 42 projecting from the opposite sides of the manually operated handle lil.- The operating handle lfl is pivotally mounted on a pivoted support ld which is normally maintained releasably in operative position by a latch 136 pivoted to a pin 48 extendingvthrough aligned'openings in the sheets i6, le. The pivoted support li isiormed of two spaced parallel parts pivotally supported on a pin 583 and the handle ld is pivotally supported between said parts on a pin 52 extending into aligned openings in said parts. The opposite ends of the springs tend to move toward each other. Thus, when. the handle Ill is moved from the circuit closed position shown in Fig. 1 to the circuit open position shown in Fig. 2, the switch arm 3&3 will remain in circuit closed position until the line of force of the springs 38 passes beyond l the dead center position or across the pivot 36 of the switch arm. The switch arm 3Q 'will then move into circuit open position with a snap action independently of any further movement of the operating handle ld. The operating handle will move of its own accord into the open-circuit position illustrated in Fig. 2 when the line of action of the springs crosses the handle pivot 52. When it is desired to move the switch arm 3d into circuit closed position, the handle lil is moved in the reverse direction until the line of force ofthe springs' passes beyond dead center position. The switch arm 3B will then move into circuit closed position and into electrical engagement with the stationary contact 3B andthe handle will stay in circuit closed position under action of the springs. It is apparent, therefore, that the breaker is operable manually to open and close the circuit with a snap action which prevents excessive or long continued arcing between the movable and stationary contact members.

'I'he supporting member @il is arranged to move about its pivot 5@ in a counter-clockwise direction into an inoperative position upon the occurrence of a relatively longcontinued predetermined overload current. To this end, a bimetal strip 54, comprised of two metals of dissimilar coeiiicients of expansion secured together back to back, is ixed at its lower end to a terminal 56 having outwardly projecting ears 58 extending through openings and iixed in the sheets I6, I8 to anchor the terminal 5B in position. The lower end of the terminal 56 is bent horizontally and is provided with a threaded opening for receiving a connecting screw Bil for a circuit conductor. 'I'he upper end of the terminal 55 is provided with a threaded hole for receiving an adjusting screw 52. The adjusting screwA 62 extends through the opening and bears against the bimetal strip 5e to adjustably position the upper free end of the strip 5G relatively to the lower end 655 of the latch Q6, which, when suihciently thermally warped, is arranged to engage and move away from holding relation with the support dll, to permit the release of saidsupport. By positioning the free end of the bimetal strip 5&1 further away from the end of the` latch 46, the free end thereof will have to warp farther before it will move the end of the latch suiciently to trip the latch le to free the support im and to permit it to move to inoperative position.

When the support lll is freed from the latch 46, the springs 38 become eiective to move the support 4d into the position shown in Fig. 3 since the line of action of the springs'lies to the left of the pivot 5U for the support. The handle M which, as shown in Fig. l, bears against the pivot 4pin 5G will be swung in a counter-clockwise direction about the pivot pin 50 as a fulcrum, the handle also camming on the pin by reason of the inclined cam face 5l of the handle. When the spring supporting pinll of the handle crosses the center line passing through-the spring supporting pin Alll? of the switch arm' and the pivot .36 of the switch arm the switch arm will -move to open-circuit position and will carry the line of action of the spring across the pivot pin 52 of the handle thereby moving the handle to opencircuit position. Thus, the switch arm 3d will be moved in a counter-clockwise direction from the position shown in Fig. l to the position shown in Fig. 3. The extent of opening or clockwise movement oi the switch arm 3d is limited by a stop B6 xed in position between the sheets l E, i8.

When it is desired to reclose the breaker after automatic opening thereof, it is necessary only to move the handle from the position shown in Fig. `3 toward the right. The handle Ui will then engage the pivot pin 5U about which the handle ill and the support ld will fulcrum and cam to move the support lll into the position shown in- Fig. l. During this resetting movement, the line of action ofthe springs 38 will pass across and to the right of the pivot 36 for the switch arm 3Q which then, oi course, will move into circuit closed position with a snap action. If the bimetal strip all has returned to its normal position, as shown in Fig. 1, the latch ll will engage the end of the support 44 and will maintain the parts in circuit closed position. If, however, the latch le has not returned to the position shown in Fig. 1 the circuit will remain closed as long as the operator holds the operating handle l5 in the position shown in Fig. l.

I claim:

1. In a combined switch and circuit breaker, the combination of a switch arm movable between circuit 'open and circuit closed positions, a fixed pivot for said movable switch arm, a pivoted operating handle movable between said circuit open over-center spring 'connecting said operatinghandle and said switch arm, a pivot for said supporting arm displaced relatively to said pivots for theswitch arm and for the operating handle to locate the pivots for the operatinghandle and the switch arm on one side'and the pivot for the supporting arm on the opposite side of the line of action of said over-center spring when the parts are invcircuit closed position, and current responsive means for maintaining said supporting arm in operative position and arranged upon the occurrence of a predetermined abnormal current condition to release said supporting arm to permit movement thereof and to move the pivot for the operating handle to the other side of the line of force of the over-center spring to cause said spring to move said operating handle into circuit open position and subsequentli7 to move said contact .carrying arm into circuit open position with over-center spring snap action.

2. In a combined switch and circuit breaker, a Contact carrying arm movable between circuit open and circuit closed postions, a fixed pivot for said contact carrying arm, a pivoted operating handle, a. displaceable support upon which said operating handle is pivoted, a iixed pivot for said support, over-center spring means connecting said operating handle and said contact carrying arm, and current responsive means normally maintaining said support in operative position but releasable upon the occurrence of a predeterminedoverload current to move into an inoperative position and causing the operating handle to iulcrumabout the pivot of said support to cause the operating handle to rotate in a circuit opening direction, thereby causing the over-center spring means to be moved beyond dead center position to cause movement of the contact carrying arm from circuit closed to eircnit open position with over-center spring snap action.

3. An electric switch 'comprising a pivoted switch member, a pivoted operating member, an over-center spring operative to move said switch member with snap action from a position corresponding to circuit'closed position to a position corresponding to circuit open position in response to corresponding movements of said operating member and to bias said switch member to remain in whichever of said positions it is located, and current-responsive means to permit shifting oi the pivot of said pivoted operating member to effect automatic movement of said switch member from circuit A.closed to circuit open position and corresponding movement of said' operating member, said operating member having means responsive to manual pressure thereon in a circuit closing direction preventing the shifting of the/pivot thereof', and means responsive to movement of said operating member in a circuit closing direction operative to restore the shifted pivot thereof.

4. An electric switch comprising a pivoted switch member, a pivoted operating member, an over-center spring operative to move said switch member with snap action from a position corresponding to circuit closed position to a position corresponding to circuit open position in response s to corresponding movements of said operating Imember and to bias said switch member to remain in whichever ofv said positions it is located,

f and current-responsivemeans to permit shifting of the pivot of said pivoted operating member to eii'ect automatic movement of saidpswitch member from circuit closed to circuit open position and corresponding movement of said operating member, said operating member having means resistive to manual pressure thereon in a circuit closing direction preventing the shifting and an over-center spring operative followingv release of the trip member by the electro-responsive means iirst to rotate the trip member about its pivot, then to rotate the manually operative l means about its pivot, and ultimately to rotate the contact carrying member about its pivot from circuit closed to circuit open position with overcenter spring snap action.

6. In a combined switch and circuit bieaker, a

contact carrier movable between circuit open and circuit closed positions.. a manually operable member mounted on a movable'pivot, means normally and releasably supporting said pivot, and' an over-center spring bridging said pivot and having its ends connected respectively to said contact carrier and said manually operable member and biasing said pivot away from its supported position and in direction across the line of action of the spring, said means being operative under normal circuit conditions to release said pivot, and said spring then being operative to effect relative movement of the line of action of the spring and said pivot across each other thereby to eiect snap movement of the contact carrier from its circuit closed position to its circuit open position.

7. In a combined switch and circuit breaker, a contact carrier movable between circuit open and circuit closed positions, a manually operable member mounted on a movable pivot, a swinging latch member on which said manually operable member is pivotally mounted, means normally maintaining said latch member in latched position and operative in response to abnormal circuit conditions to release the latch member, and an over-center spring bridging the latch member and having its ends connected respectively to said contact carrier .and said manually operable member and biasing said latch member away from its latched position in direction across the line of action of the spring, said spring, upon release of the said latch member, being operative to effect relative movement of the line of action of the spring and said movable pivot 0f the manually operative member across each other thereby to effect movement of the contact carrier from its circuit closed position to its circuit open position with over-center spring snap action.

8. In a combined switch and circuit breaker, three pivoted members of which one is a contact-- carrying member, another is a trip member, and the third is a manually operable member whose pivot is on the trip member, means normally maintaining the trip -member in operative position and responsive to abnormal circuit conditions to release the trip member,` and an over-center spring bridging all of the pivots of said pivoted members andhaving its ends connected respectively to said contact-carrying member and said manually operable member and biasing said trip .member from its said operative position in direction across the line-of action of the spring, said spring, upon release of the trip member, being operative to eect relative movement of thelline-v of action or the spring and said pivot of the man- 'sponsiveto abnormal circuit conditions to release the trip member, an over-center spring bridging all of the pivots of said pivoted members and having its ends connected respectively to said contact-carrying member and said manually operable member and biasing said trip member from its said operative position in direction across the line of action of the spring', said spring, upon release of the trip member, being` operativev to move the said movable pivot of the manually operable member in direction across the line of action of the spring, and there being means on said manually operable member for coacting with said xed pivot. of the contact-carrying member, to shift the line of action of the spring in direction across said movable pivot.

10. In a combined switch and circuit breaker, a manually operable member, a contact-carrying member mounted on a xed pivot-,means relees ably supporting the manually operable member in operative position on a movable pivot, and an over-center spring maintaining the manually operable member and the contact-carrying member in their circuit closed positions with the line of action of the springen one side of both the said xed pivot and the said movable pivot, said means' being operative in response to abnormal circuit conditions to release said movable pivot 4of the manually operable member thereby to permit movement of said movable pivot by the. spring across the line of action of the spring, and said spring then being operative to shift its line of 'action to the other side of said iixed pivot to effect over-center spring snap action of the conv tact-carrying member from its said circuit closed position. 4

' CARL A. CHRISTOON.

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