US2813951A - Circuit breaker - Google Patents

Description

A. F. KOLB ET AL CIRCUIT BREAKER 4 Sheets-Sheet l Nov. 19, 1957 Filed oct. 16, 1955 APT/,'02 F) /COLB fue,

Nov. 19, 1957 A. F. KoLB ET A1. 2,813,951

CIRCUIT BREAKER Filed Oct. 16, 1953 4 Sheets-Sheet 2 A1- Ansv Nov. 19, 1957 A. F. KoLB ET AL 2,813,951

' CIRCUIT BREAKER Filed oct. le, 1955 4 sheets-sheet FIO 1% I4 62 7e,

/NvENToRs 4 THEODOP f7 P05/NG ,/COLB Fl 7 l ARTHUR F CIRCUIT BREAKER Filed 0013. 16, 1955 4 Sheets-Sheet 4 INVENToRs A ,Q TNI/,Q E KUL B ryHfoof f7 P05/N6 A 'QRNEY CIRCUIT BREAKER Arthur F. Kolb, Milwaukee,

Whitefish Bay, Wis., assignors to Cutler-Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Application October 16, 1953, Serial No. 386,436 12 Claims. (Cl. 20u-116) and Theodore F. Rosing,

This invention relates to circuit breakers, particularly small circuit breakers adapted for use as motor starters.

The principal object of this invention is to provide a simple reliable and inexpensive circuit breaker of this character.

A further object of this invention is to provide a circuit breaker of this character which is easy to assemble, requires a minimum number of working parts, is fully protected .against deleterious etects from sparking and external dust and dirt particles.

A still further object of this invention is to provide a circuit breaker of `this character which does not require detrimentally sharp hammer blows to open the circuit.

In obtaining these objects the circuit breaker is provided with the following general characteristics: The movable contact ycarrying bridging members are loosely mounted on a contact bar which is slidably guided in the base and cover forming the circuit breaker housing. Such bridging members are spring biased toward closed circuit position and with the contact bar move back and forth in a path substantially perpendicular to parting line between cover and base. This facilitates assembly of the circuit breaker. The contact bar is moved toward the closed end of the cover to open the normally closed contacts by a manually controlled over-center spring action carried in the base. This action is installed in the base by the simple expedient of axially sliding its main pivot into a bearing in the base while such action is momentarily held in place. The action includes a contact operating lever which engages with the contact bar to move it to opened position. Such lever has an overload bar which in overload conditions is engageable by an overload lock and reset lever also included in such action. These levers, a spring support and a manually operated lever are all mounted on the same pin in such action. While there is a slight tolerance built into the mechanism to provide for wear of the contacts, this is not sufficient to impart a hammer blow in the opening of the contacts. Instead the overcenter spring action imparts a positive and instantaneous opening to the contacts without the necessity of damaging hammer blows which soon wear and break down such small lightly constructed vcircuit breakers. The base and the cover completely enclose the contacts and all -operating members, except the handle of the manually operated lever, to protect them from dust and dirt and to keep harmful sparking fully shielded.

For a more detail description of this invention reference should be made to the following description of a specic embodiment read in connection with the accompanying drawings, in which:

Figure l is a top plan View of a circuit breaker embodying the present invention with the manually operated lever in or position;

Fig. 2 is a sectional view taken on the line 2 2 of Fig. l;

2,813,951 Patented Nov'. 19, 1957 htice tFig. 5 is a sectional view taken on the line 5 5 of Fig. 3;

Fig. 6 is a sectional view taken on the line 6 6 of Fig. 3;

Fig. 7 is a sectional view taken on the line 7 7 of Fig. 5;

Fig. 8 is a sectional View taken on the line 8 8 of Fig. 5; and f Fig. 9 is an exploded prospective view of the circuit breaker shown in Figs. 1-8 (incl.)

The circuit breaker illustrated in the drawings is a multiple pole starter rated at approximately l horsepower, single phase on and 230 volts. Completely assembled it is approximately 11/2 inches wide, 21/2 inches long and 2 inches high. Such small circuit breaker has a base 1l) and a cover 12 formed of molded insulating material which are secured to provide a housing for the complete circuit breaker operating mechanism except the handle of the manually operated lever. On a ilat portion of the base `10 facing the cover 12 there are mounted xed contacts 14 into the threaded supports of which are threaded exterior terminal screws 16. Between these contacts is a groove 18 for guiding the contact carrier. Slots 20 transverse to such groove guide the linger of the contact operating lever. A projection 22 on the base 10 houses the thermal release assembly. A rectangular hole 24 accommodates the handle of the manually operated lever and provides shoulders limiting the extreme movements of such handle. The over-center spring action is held in the base 10 during assembly of the circuit breaker by having an extending end of the pivot of such action project into a bearing 26 in such base. Opposite this bearing is a cylindrical groove 27 which cooperates with a similar cylinder groove in the cover to form the other bearing for such pin.

The cover 12 has a recess 2S which accommodates the swinging elements of the over-center spring action. At the bottom of this recess is a groove 30 which guides the end of an overload lever. The right-hand wall of such recess has a semi-cylindrical groove 32 (see Figs. 4 and 8) which provides an abutment for the spring of the over-center spring action. Adjacent to the recess 2S are a pair of spaced recesses 34 (see Figs. 6 and 7) terminating in cylindrical wells 36 which provide operating space for the contact bridging members and their compression springs. Slots 38 cooperating with the grooves 13 in the base 1l) provide the complete guide for the contact bar. A semi-cylindrical bearing 46 in the cover l() (see Fig. 5) cooperates with the semicylindrical bearing 27 in the base 10 to form the outer bearing for the main pivot of the over-center spring action.

The movable contacts of the circuit breaker are mounted on a pair of bridges 42 apertured to loosely slide on tongues 44 on a contact carrier 46. The carrier 46 is made of insulating material such as melamine and is slidably guided in the groove 18 and slots 38 to simultaneously move the bridges 42 in the recesses 34 with the contacts thereon in alinement with respective pairs of the fixed contacts 14. The bridges 42 are continually urged toward the closed circuit position shown in Figs. 3, 6 and 7 by compression springs 48. lt is relatively simple to assemble the bridges 42, carrier 46 and springs 48. The springs 48 are seated in the wells 36 of the cover. The bridges 42 are placed on the tongues 44 and the contact carrier 46 iitted in the groove 18 of the base 10. When the cover 12 is placed on the lbase 10, the springs 48 will be properly compressed. The contact carrier 46 has a centrally located slot 50 which engages a finger on the contact operating lever to aid in electing its movement toward circuit opened position.

The over-center spring action includes a manually operated lever 52 to which is pivoted by a single main pivot 74 a spring support 70, a contact operating lever 82, and an overload and reset leverV 90. An over-center spring 76 extends between the bridge of the spring support 70 and a spring yoke 62 pivoted to the manually operated lever 52. The manually operated lever S2 is made of insulating material and has a hand engageable iinger which in the assembled condition projects outwardly of the housing through the hole 24. A pair of spaced shoulders 54 alternatively engage the ends of hole 24 to establish the off and on position of the lever 52. A pair of trunnions 56 with bearings 58 therein are spaced by a groove 60. The latter slidably guides the spring yoke 62 pivoted to the lever 52 by a pin 64 iitting in an elongated bearing 66 in the lever 52 and passing through a hole 68 in such spring yoke. The spring support 70 is U-shaped and has a connecting bridge and a pair of legs terminating in apertured ends 72. These ends straddle the trunnions 56 with the apertures aligned with bearings 58 and mounted on the main pivot 74. The tension spring 76 has one end anchored to the bridge of support 70 and its other end engaged in a hole 78 in the yoke 72. This yoke has an arcuate slot 80 which permits it to swing about the pin 64 without interfering with the main pivot 74. Such linkage will cause the spring support 70 to move back and forth between its limit position of Fig. 2 and its limit position of Fig. 3 upon swinging the lever 52 back and forth between its open circuit position of Fig. 2 and its closed circuit position of Fig. 3. Such motion after dead center is reached is very rapid.

In normal operation the motion of the spring support 70 is transmitted to the contact carrier 46 by the contact operating lever 82. This lever has a pair of supporting legs straddling the spring support 70 and pivoted on the main pivot 74. Such contact operating lever 82 has an extending linger 84 slidable in the slots 20 and seated in the slot 50 of the contact carrier 46. The bridge of lever 82 hasy an arcuate recess 86 which iits around the spring 76 to permit the clockwise edges of the bridge to be engaged by the legs of the spring support 70 in the Y normally operating ott position of the circuit breaker of Fig. 2. The `contact operating lever 82 also has `an overload bar 88 which is engaged by the overload and reset lever 90 when the latter is `released upon an overload.

The overload and reset lever 90 has a main bridge with spaced supporting legs 92 straddling the contact operating lever 82 and pivoted on the main pivot 74. The lever 90 also has a spring anchor 94 with an outer supporting leg 96 also pivoted on the main pivot 74. A tensioned overload spring 98 extends from the anchor 94 to a pin 100 secured in the base 10. A locking arm 102 formed as part of the lever 90 has a spring finger 104 normally engaged with a ratchet 106 of a thermal release assembly 108. Such assembly is well known and is shown and described in Patent No. 2,261,632 issued November 4, 1941 for Electric Circuit Mechanism. The ratchet 106 is normally held against rotation until the heater coil 108. connected to a terminal 110 and the adjacent terminal 16, melts the eutectic solder upon occurrence of an ove-rload. The ratchet 106 will then rotate and release the overload and reset lever 90 which will under iniiuence of spring 98 operate to open the circuit. The terminal 110 is carried in a plate 112 to which is threadedly fitted a terminal 114 for external connection.

To assemble the over-center spring action, the spring yoke 62 is placed in the groove 60 and pin 64 inserted in bearing 66 through hole 68. Then the spring 76 is secured to the anchor 78. The spring support 70, contact operating lever 82 and overload and reset lever 90 are then iitted over the trunnions S6 and the main pivot 74 inserted through them and the bearings 58 until its inner end (left as viewed in Fig. 9) is tlush with the inner of the legs 92. The spring 76 is then connected to the support 70. The action is assembled as a unit into the base 10 with the handle of the lever 52 projecting out of hole 24. The main pivot 74 is then moved inwardly, so that its inner end slides into the bearing 26 thus holding the action in place. After the contact bar 46 and spring 98 are assembled in the base 10, the cover 12, with bridges 42 and springs 48 in place, is placed on the base 10 and secured by screws 116 which are threaded into mounting strips 118.

Starting with the circuit breaker in the oli position, shown in Figs. i and 2, assume that the handle of the operating lever 52 is swung from the o position to the on position shown in Fig. 3. During the first part of such movement the contact operating lever 82 holds the spring support 70 in the position shown in Fig. 2. As the pin 64 moves clockwise about the main pivot 74, such pin, pivot and anchor 78 approach a position of alignment with the central axis of spring 76. Slightly before such alignment position is reached the force exerted by springs 48 is sufficient to overcome the then opposing force of spring 76, and movement of the contact carrier toward closed position results in the forced movement of lever 70 through the aforementioned aligned position to its opposite extreme position shown in Fig. 3. During the aforementioned movement pin 64 moves to engage with the other end of slot 66 in lever 52.

Starting with the parts shown in the on position of Fig. 3, movement of operating lever 52 in the counterclockwise direction to the olf position shown in Fig. 4 will cause pin 64, pivot 74 and anchor 78 to be brought toward the aforementioned alignment position. During such movement pin 64 moves from the right end to the left end of slot 66 thereby providing a slight lost motion action, offsetting any retarding tendency caused by the speed or manner of movement of lever 52. Spring support 70 is held against the groove 32 as shown in Fig. 3 during the initial part of such movement. As the alignment position is passed, the tension of the spring 76 moves spring support 70 rapidly in the clockwise direction from such position, to the position shown in Fig. 2. The legs of the spring support 72 will Contact the bridge of operating lever 82 and swing it clockwise to the position shown in Fig. 2 with a rapid motion but Without hammer action. The nger 84 instantly depresses the contact bar 46 with the consequent opening of the contacts as the effective force of spring 76 is considerably greater than the combined effective force of springs 48.

With the circuit breaker in the normally on position shown in Fig. 3, an overload will release the ratchet 106 and the overload and reset lever will instantly pivot under the influence of spring 98 to the position shown in Fig. 4. Its arm 102 will engage the overload bar 88 and swing the contact operating lever 82 to the circuit open position shown in Fig. 4. This takes place without any interference to or from the manually operated lever 52, the over-center spring 76, and the spring support 82. After the overload has been removed and the solder in the thermal element hardened, the circuit breaker may be reset. This is accomplished by swinging the manually operated lever 52 from the on position of Fig. 4 to the off position of Fig. 2. This movement causes the lefthand lower edge of such lever to engage the bridge of the lever 90 and swing such lever counterclockwise to carry the arm 102 to the position shown in Fig. 2, sothat the spring 104 will again engage with the ratchet 106 and hold such lever with energy stored in spring 9S. Lever 90 in so moving disengages from lever 82, and the latter momentarily freed rotates a slight Iamount in the counterclockwise direction thereby permitting contact carrier 46 to move a slight amount toward contact closed position. During the aforementioned resetting operation, spring support 70 is caused to snap over-center to the position shown in Fig. 2, and in so doing engages with lever 82 to drive the latter in the clockwise direction before it can move freely any appreciable amount in the counterclockwise direction.

It will be observed that because lever 90 can move lever 82, to contact opening position independently of lever 52 and spring carrier 70, that the circuit breaker is of the trip-free type, that is to say, the contacts cannot be closed by movement of lever 52 to on position, following resetting operation of the latter if the thermal element has not rehardened.

While there is shown a particular embodiment of this invention, many modications may be made land it is contemplated that the following claims cover any such modifications as fall within the spirit and scope of this invention.

We claim:

1. A circuit breaker comprising a movable contact constantly biased toward closed circuit position, an insulating contact bar having a projection along which said contact is movably guided, a housing providing guides for said bar, a lever engageable with said bar, an over-center spring action manually operable to one position to move said lever and thereby overcome said bias to move said contact `to open circuit position and manually operable to a second position to permit said contact to move to closed circuit position under its bias, and means responsive to current overload to move said lever yand operate said contact to open circuit position independently of said overcenter spring action.

2. The combination according to claim 1 in which said housing includes a base and a cover and said guide directs said bar to movement in a path substantially perpendicular to the parting line between said cover and base.

3. The combination according to claim 1 in which said action includes a main pivot having limited axial movement and said housing has a bearing receiving an end of said pivot following axial movement thereof.

4. A circuit breaker comprising an insulating base having an inner at surface, a bearing in said base having an opening in said surface, a semi-cylindrical groove in said base aligned with said bearing, -a movable over-center spring action in said base and guided by said surface, a main pivot for said action having one end projecting into said bearing and the other end resting in said groove, and a cover for said circuit breaker having a semi-cylindrical groove cooperable with said iirst groove to form a bearing for said other end of said shaft, said second groove having an abutment engageable with the end of said pivot to prevent axial displacement thereof.

5. A manually operable over-center spring action for the movable contact of a circuit breaker comprising a main pivot, a manually operated lever on said pivot, a contact operating lever swingably mounted on said pivot, said lever having a contact operating finger and an overload bar, a spring support swingably mounted on said pivot engageable with said contact operating lever, a spring acting between said spring support and said manually operated lever, and an overload lever swingably mounted on said pivot and operable when released to engage said overload bar and operate said contact operating lever without movement of said spring support.

6. The combination according to claim 5 in which said overload lever has a portion engageable by said manually operated lever to operate said overload lever for resetting thereof.

7. The combination according to claim 5 in which said overload lever has a spring anchor integral therewith and pivoted on said pivot.

8. A circuit breaker comprising a movable contact constantly biased toward closed circuit position, a slidable contact bar, a manually operable over-center spring action, a contact operating lever engageable with said bar, and a spring support positioned closely adjacent said lever in circuit closed position and immediately engageable with said lever as said over-center spring action is operated to circuit open position.

9. The combination according to claim 8 in which said over-center spring action has a manually operated lever having a pivotal axis and an elongated bearing spaced from said axis, there being a pin in said bearing, and a spring anchored on said pin and said spring support, said pin sliding from end to end of said bearing as said action passes over-center to eliminate possibilities of wavering movement due to manual sluggishness at the overcenter position.

10. A circuit breaker comprising an insulating base having an opening therein, a groove in said base, a slot in said base transverse to said groove, a fixed contact on said base adjacent said groove, a contact bar slidably guided in said groove and engageable with a movable contact to move such movable contact to circuit open position, an over-center spring action mounted in said base having a manually operated lever projecting through said opening, said action including a contact operating lever having a finger guided in said slot and engageable with said bar to move said bar to circuit open position, an insulating cover for said base forming therewith an enclosure for said over-center spring action, a recess and well in said cover, a movable contact operable in said recess, and a spring in said well for normally biasing said movable contact into engagement with said fixed contact.

11. A circuit breaker as claimed in claim 10 in which said over-center spring action includes a swingable spring support for moving said contact operating lever to circuit open position, said cover having a portion for engaging said spring support in the circuit closed position thereof and holding said support closely adjacent said contact operating lever so that upon operation of said over-center spring action said support will engage and move said contact operating lever without a hammer blow.

12. A circuit breaker as claimed in claim 10 in which said over-center spring action includes a spring biased swingable overload lever having an arm engageable with said contact operating lever to move said lever to circuit open position, there being a groove in said cover for guiding the end of said arm.

References Cited in the file of this patent UNITED STATES PATENTS 2,166,545 Getchell July 18, 1939 2,343,264 Platz Mar. 7, 1944 2,418,537 Wood Apr. 8, 1947 2,611,055 Webster Sept. 16, 1952 2,657,289 Wolfe et al. Oct. 27, 1953 2,660,642 Warren Nov. 24, 1953 2,703,350 Rosing Mar. 1, 1955 FOREIGN PATENTS 455,204 Great Britain Oct. 15, 1936

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