US3030472A - Automatic multi-cycle reclosing switch or circuit breaker - Google Patents

Description

A ril 17,1962 H. A. CUBBERLY 3,030,472

AUTOMATIC MULTI-CYCLE RECLOSING SWITCH OR CIRCUIT BREAKER Filed Nov. 50, 1959 IN VENTOR HENRY A. CUBBEZRLY ATTORNEY United States Patent 3,030,472 AUTOMATIC MULTI-CYCLE RECLOSING SWITCH 0R CIRCUIT BREAKER Henry A. Cubherly, Hydes, Md., assignor to The Bendix Corporation, a corporation of Delaware Filed Nov. 30, 1959, Ser. No. 856,195 6 Claims. (Cl. 200-116) This invention relates to thermal-responsive switches or circuit breakers of that type which disconnect an electric circuit should an abnormal temperature or current overload occur and automatically reclose the circuit should the temperature or overload condition return to normal, the cycle being repeated a given number of times before the circuit is permanently broken should the abnormal condition persist.

The invention includes among its objects:

To provide a switch of the type specified which is relatively simple and low-cost in construction, is compact and capable of being installed in a restricted space.

The'provision of a thermally-responsive automaticallyreclosing switch which may be conveniently adapted for response to an abnormal air temperature condition, as in air-conditioning and fire-protection systems, or to an abnormal current condition, or to both air-temperature and current flow conditions of an abnormal nature.

To provide a small compact switch of the type specified utilizing pawl and ratchet mechanism which may consist of simple stampings or like easily-fabricated parts.

The foregoing and other objects and advantages will become apparent in View of the following description taken in conjunction with the drawing, wherein:

FIGURE 1 is a view in side elevation of a switch in accordance with the invention with the housing cover removed;

FIGURE 2 is a section taken substantially on the line 2-2, FIGURE 1; and

FIGURE 3 is a fragmentary view of the switch of FIGS. 1 and 2, showing a thermal switch member, the use of which renders the switch responsive to both excessive air temperature and current fiow.

Referring to the drawing in detail, the switch housing is indicated at 10, it has a side cover removable to gain access to the switch mechanism, and a bolting-on flange 11.

The switch as shown in FIGS. 1 and 2 is responsive to an excessively high-temperature condition in an area to the left of FIG. 1. Such area could be a chamber in which is housed the mechanism or apparatus to be. protected from an excessively high or low temperature, or it could be a storage room or compartment or other area in which the temperature may rise above or below some predetermined value. The side wall of the housing 10 facing this area is provided with an opening 12 in which is located a thermal-responsive member, here shown in the form of a bimetal strip 13, having. its one end fixed, as by screw 14-, to the flange 11, and its opposite end projecting free. An insulated finger 15 is fixed to the free end of the bimetal strip 13 and projects inwardly for operative engagement with a resilient pawl-driving member in the form of an over-center leaf spring 16 (which could also be in the form of a bimetal strip as in FIG. 3), provided with a contact 17, adapted to engage a terminal contact 18, to which a lead 19 is attached for connection in a power circuit. The other circuit terminal 20 is located at the lower end of the spring 16 and has connected thereto lead 21. The spring 16 is normally biased to circuit-closing position, which as viewed in FIG. 1 is toward the left or counterclockwise.

The one end (lower end as viewed in FIG. 1) of the spring strip 16 is fixed in a slot formed in a boss 22, projecting from the adjacent wall of the casing 10, while 3,030,472 Patented Apr. 17, 1962 'ice its opposite or upper end loosely engages in a slot 23, formed in the adjacent end of pawl arm 24, having a resilient or spring-biased pawl 24 secured to its opposite or upper end. The pawl arm 24 is pivotally anchored at 25 to the wall of the case 10. A ratchet member 26 has an integral leaf-spring extension 27 fixed in a slot formed in the boss 22 in a manner such as to normally bias the ratchet member to the right or in a counterclockwise direction as viewed in FIG. 1. The upper edge of the ratchet member is formed with ratchet teeth 28, and projecting from the upper left-hand corner of said member is a finger 29, terminating in a reversely-turned latch portion 29', the function of which will presently be apparent. An open-circuit locking plunger 30 is slidaoly mounted in a guide block or boss 30, suitably secured to, or formed integrally with, the wall of the casing 10. The lower end of this plunger remains just above the upper end of the spring strip 16 until the ratchet 26 is actuated to final open-circuit position in a manner to be explained. A spring 31 normally urges the plunger 30 to its down position; it (the spring) is anchored at its one end to the case 10 and at its opposite end issuitably secured to the upper end or top of the plunger 30 and has a lateral extension 31 beneath which the latch 29 engages until it releases the plunger for movement to circuit-break position. A ratchet pawl 32 cooperates with the pawl 24'.

A manual reset lever 33 (which if desired could be electrically controlled as by a solenoid) is pivotally anchored at 34 to the case 10; its inner extremity normally lies beneath the lateral extension 31' of spring 31 and a like extended portion of pawl 24, note FIG. 2, so that when it is rotated in a clockwise direction, should the said plunger and pawls then be in circuit-break position, it will raise these members, freeing spring strip 16 for return to circuit-make position.

Operation rection, separating contacts 17 and 18 and swinging pawl arm 24 in a counterclockwise direction. Since the pawl 24' is in engagement with the first tooth to the left on the ratchet 26, it will move the ratchet to the left or counterclockwise (flexing spring strip 27) the distance of one tooth, but this amount of travel is not suificient to move the inturned latch portion 29' of finger 29 from beneath the lateral projection -31 of spring 31, and since 31 is secured to the upper end of plunger 30, the latter wiil remain in its up. position as in FIG. 1. Holding pawl 32 will now engage in the third tooth from the left as viewed in FIG. 1.

The respective parts will remain in open-circuit position, as above described, until the thermal strip 13 cools and returns to its normal shape, whereupon finger 15 frees spring strip 16 and the latter, being biased in a counterclockwise direction, closes contacts 17 and 18; at the same time the pawl 24 is rotated further in a clockwise direction, moving the tooth of pawl 24' into the next succeeding tooth to the right on ratchet 26 (the center tooth as here shown). This will bring the parts to the position shown in FIG. 1, except that the pawl 24', instead of engaging in thefirst tooth to the right on ratchet 26 will engage in the center tooth, and the holding pawl 32 will be in the third or last tooth. If now the overheated condition again occurs, the above cycle such that the latch 29' moves out from beneath the lateral 7 extension 31' of spring 31, whereupon the latter drives the plunger downwardly to the left of the upper end of the spring strip 16, locking the latter in open-circuit position. 1

It will be observed that the switch as illustrated herein will reclose only once after the first circuit break. However, to repeat the cycle more than once requires only additional teeth on the ratchet 26 and a corresponding extension to the right of the latch 259' of finger 29.

As heretofore indicated, the reset lever 33 has its inner extremity engaging beneath the lateral extension 31' of spring 31 and also beneath the pawl 24. Hence, to reset the switch when the plunger is down in circuit-break or lockout position, it is only necessary to rock the lever in a clockwise direction, raising the plunger 30 and the pawl 24, whereupon the plunger will move clear of the upper end of spring strip 16 and the spring-biased ratchet 26 will move to the right or in a clockwise direction until the pawl 24 is in alignment with the first tooth (starting at the left) on the upper end of said ratchet. The parts will then be returned to the position shown in FIG. 1.

To render the switch both air-temperature and currentresponsive, it is only necessary to replace the spring strip 16 of FIG. 1 with a bimetallic type resistor strip such as shown at 16 in FIG. 3. Should there be an excess current surge, strip 16' will deform and swing pawl lever 24 past dead center in a counterclockwise direction, it being understood that the bimetallic strip 16 will move clockwise when heated by excessive current flow, The cycle from then on will be the same as that described above in connection with the switch of FIGS. 1 and 2. Should it be desired to have the switch responsive to current overload only, then only the strip 16' of FIG. 3 need be used, the strip 13 and finger 15 of FIG. 1 then being omitted.

The operation as set forth herein is predicated on an over-temperature or excess-current condition, or both. However, it will be obvious that by reversing the position of the bimetal strip 13 of FIG. 1, or the bimetal 16' of FIG. 3, the switch could be made to respond to a predetermined low-temperature or low-current condition. Also, by an appropriate arrangement of the bimetal strips 13 and/or 16, the switch could be made to respond to a low temperature condition, low current how, or a combination of temperature and current flow conditions.

The main components of the switch maybe fabricated from simple sheet metal stamping and machined components, or they may consist of stampings, molded parts and/or simple machine components, as best suited to existing facilities. Also, the switch may readily be made small and compact for installation Where space is at a premium.

What I claim is:

1. In a circuit breaker of the multi-cycle type, a resilient contact make-and-break element normally biased to circuit-closing position and movable against its biasing force to a circuit-break position in response to an abnormal temperature or current condition, a member movable to a first position freeing said element for repeated movement to circuit make-and-break positions and to a second position locking said element in circuit-break position, a latch normally holding said member in said first position,

latch to a position in which it releases said member for movement to its second or locking position, and a p w cooperating with said ratchet and driven by said element to eifect a positive step movement of said ratchet each time the circuit is broken until said latch releases said member.

2. In a circuit breaker of themulti cycle reclosing type, a resilient contact make-and-break element consisting of a bimetallic spring strip across which the circuit is completed, the one extremity of said strip being anchored and the opposite end projecting free, said strip being nor mally biased to circuit-closing position, a member movable to a first position enabling said spring strip to flex repeatedly to circuit make-and-break positions and biased to a second position locking said spring strips in circuitbreak position, a latch normally holding said member in its first position, a toothed ratchet arranged to progressively move said latch to a position where it releases said member for movement to its locking position, a pawl.

for operating said ratchet, and an operative connection between the free end of said spring strip and said pawl whereby a step movement is imparted to said ratchet each Y timethe circuit is broken until said latch releases said element consisting of a strip of resilient conductive material having one extremity anchored to said case and the opposite end projecting free, a member for locking said strip in circuit break position, said member being movable to a first position enabling said strip to flex repeatedly to circuit make-and-break positions and to a second position locking said strip in circuit-break position, means biasing said member to lock-out position, a latch for holding said lock-out member in its first position, a toothed ratchet for moving said latch to a position freeing said lock-out member for movement to its second position, a pawl for driving said ratchet step by step until the latch releases said lock-out member, and an operative connection between the free end of said'spring strip and said pawl whereby when the strip is flexed to circuit break position it acts through said pawl to drive said ratchet step by step in a direction to release said latch.

4. A circuit breaker as claimed in claim 3 wherein there is a bimetallic element responsive to an abnormal temperature condition in the region of the switch, said bimetallic element having an operative connection with the free end of said strip tending to move the latter to' circuit-break position.

5. A circuit breaker as claimed in claim 3 wherein said spring strip is comprised of a piece of bimetal re and said pawl from engagement .with the teeth of the ratchet.

References Cited in the file of this patent UNITED STATES PATENTS 2,298,143 May Oct. 6, 1942 2,343,255 Fisher Mar. 7,1944 2,361,221 Ludwig et a1. Oct. 24, 1944 2,597,805 Kitto May 20, 1952.

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