US3796860A

US3796860A - Electrical circuit-breaker

Info

Publication number: US3796860A
Application number: US00292132A
Authority: US
Inventors: H Kick; W Schwyn
Original assignee: CMC Carl Maier and Cie AG
Current assignee: Maier C & Cie ch; ABB CMC Carl Meier AG
Priority date: 1971-09-30
Filing date: 1972-09-25
Publication date: 1974-03-12
Anticipated expiration: 1991-03-12
Also published as: IL40420A; DE2158752B1; CH543173A; DK136746C; DE2158752A1; DK136746B; NL169390C; IT967720B; NL169390B; JPS5647657B2; ATA771272A; DE2158752C2; NL7213268A; JPS4842367A; FR2154627B1; IL40420A0; SE375184B; ES407279A1; AT332482B; GB1388599A

Abstract

An electrical circuit-breaker comprising a housing, fixed and movable contact members and a breaker mechanism for actuating the movable contact member. The breaker mechanism includes a pivotable handle for manual operation of the breaker. A first axle is fixed in the housing. There is provided a first lever with two arms of unequal length, said lever being pivotably supported by said axle and being operatively connected with said handle in direction of closing the breaker by the handle. A coil spring is arranged on the axle for urging the lever in a direction to open the contacts. The first axle also carries a second lever having a coulisse mechanically engaged with the handle, that the two arms of the first lever stand nearly at an angle of 90* to each other, the summit of the angle coinciding almost with the axle and that the movable contact member is mounted on the shorter arm of the first two armed lever.

Description

United States Patent 1 Kick et al.

[ ELECTRICAL CIRCUIT-BREAKER [75] Inventors: Hermann Kick, Schaffhausen;

Walter Schwyn, Beringen, both of Switzerland [73] Assignee: Carl Maier & CIE, Schaffahusen,

Switzerland 22 Filed: Sept. 25, 1972 21 App]. No.: 292,132

[ Mar. 12, 1974 Primary Examinerlla rold Broome Attorney, Agent, or FirmWerner W. Kleeman [5 7] ABSTRACT An electrical circuit-breaker comprising a housing, fixed and movable contact members and a breaker mechanism for actuating the movable contact member. The breaker mechanism includes a pivotable handle for manual operation of the breaker. A first axle is fixed in the housing. There is provided a first lever with two arms of unequal length, said lever being pivotably supported by said axle and being operatively connected with said handle in direction of closing the breaker by the handle. A coil spring is arranged on the axle for urging the lever in a direction to open the contacts. The first axle also carries a second lever having a coulisse mechanically engaged with the handle, that the two arms of the first lever stand nearly at an angle of 90 to each other, the summit of the angle coinciding almost with the axle and that the movable contact member is mounted on the shorter arm of the first two armed lever.

7 Claims, 2 Drawing Figures ELECTRICAL CIRCUIT-BREAKER The tendency of technical evolution of circuitbreakters used for the protection of electrical conductors in buildings goes in the direction, on one hand, to reduce the dimensions, on the other hand, to improve the performance:

to increase the rupturing capacity,

- to limit the short-circuit current,

to cut the current very rapidly.

Specially in respect of the last two requirements most of the known small circuit-breakers are still inferior to the cheap and well proven. fuses. In spite of the mentioned high requirements such breakers must be fabricated at a minimum of cost.

The present invention relates to an electrical circuitbreaker of very reduced dimensions and of considerably improved performance. The main object of this invention is to provide an electrical circuit-breaker which allows to cut the current as quickly as possible. It is known that for achieving this it is necessary to use an armature of an electro-magnet, energized by the shortcircuit current, which knocks away the movable contact member and helps to accelerate the opening of the contacts.

A further object of this invention is to create an electrical circuit-breaker having a breaker actuating mechanism consisting of a minimum of structural parts, which ensure a high contact pressure, but which requires only small forces for release (minimum pressure on a pawl), which leaves enough open space for the magnetic release with an armature for knocking away the movable contact member and which is small in size.

These objects are substantially achieved, according to the invention, with a breaker mechanism which is equiped with a pivotable handle for manual operation of the breaker and an axle fixed in the housing of the breaker. On this axle pivots a first lever with two arms of different length, which can be moved in direction for closing the contacts by means of the handle. On the same axle are arranged a coil spring and also a second lever with a coulisse or slot, which is in mechanical connection with the first lever. The two arms of this first lever are nearly at right angles to each other and the summit of this angle is disposed near the axle. On the shorter arm is mounted the movable contact member.

This structure of the breaker permits to choose the length of the arms of the first lever in such a way, that the pressure on the pawl is of the same order as the pressure between the contact members. By this the forces for releasing the breaker are reduced considerably. In addition, this structure requires only few parts, for example only one coil spring serving for creating the contact pressure and also for opening the contacts. The arrangement of the parts and especially the form of the lever with two arms leaves enough open space for the magnetic release with an armature in the right direction to knock the movable contact member away from the fixed contact member, in case of a shortcircuit.

All in all, this structure of the breaker allows a considerable reduction in size, i.e., to be small enough to fit into the dimensions indicated in the German standard DIN 49,503 for breakers of much lower performance.

Several details might still increase the advantages of the invention:

The second lever may, in direction of closing the breaker, be coupled by a pawl to the first lever. To prevent the movable parts to slant sideways,

two second levers may be used and the pawl suspended between them.

The coil spring may have an outwardly extended leg in the middle, which presses on an extension of the movable contact member beyond a second axle, and the two halves of the spring on both sides of the middle leg may be wound in opposite sense.

Another possibility would be to put two coil springs on the axle, of which two neighbouring legs press on the extension of the movable contact.

The movable contact, which preferably bridges two fixed contacts, the consumption of which by the arc may be unequal, should be slightly turnable around its length direction. This may be realized with some play between the axle of the movable contact and the first lever as well as with sufficient distance between this lever and the contact in order to permit rotation of :1 0. For the same goal, two movable contacts could be used which would be electrically connected by a flexible connexion.

A preferred embodiment of the invention is illustrated, by way of example, in the accompanying draw ing, in which:

FIG. 1 is a view into the open housing of the breaker;

FIG. 2 is a sectional view of the housing.

As specially shown in FIG. 2, an axle l is fixed in a housing 14 and carries a coil spring two levers 2, 2', each with a coulisse or curved slots 2a, and between them another lever 3 with two arms of different length. The arms of lever 3 stand substantially at right angles to each other and the summit of the angle formed by said arms coincides almost with axle 1. In the coulisses or curved slot 2a of the

levers

2 and 2 cams 7 engage which protrude from the two opposite sides of a nose 6 of the handle 5 serving for manual operation of the circuit-breaker. At the ends of the two levers 2 and 2 a pawl 8 is suspended which engages with the longer arm of lever 3. A movable contact member 4 is povitably arranged at the shorter arm of lever 3 by means of a second axle 12. The spring 9 rests with two outwardly extended end portions on the housing 14. An outwardly extended leg in the middle of spring 9 presses on backward extensions 13, 13' of the movable contact member 4 beyond the second axle 12.

The extension 13' rests on a stop portion of lever 3. The spring 9 urges the contact member 4 and the lever 3 together with the levers 2 and 2' into the open position of the breaker as represented in FIG. 1.

To bring the breaker in closed position, the handle 5 is tilted to the right in FIG. 1. By this the cams 7 pull the

levers

2 and 2 upwards, which in turn by means of the pawl 8, also pivot the lever 3 in clockwise direction. The contact member 4 is thus moved toward a pair of fixed contact members 11. After the contact 4 has touched the fixed contact members 11, the movable contact member 4 rolls on the fixed contact members 11, by which the extension 13 lifts off from the lever 3. The middle leg 10 of spring 9 produces now by the aide of the axle 12 the desired contact pressure between the contact members 4 and 11.

In order that contact member 4 presses always securely on both fixed contact members 111, the contact member 4 is slightly rockable around its length axis over at least ilO. To permit this, the axle 12 must have enough play in the lever 3 and the two

extensions

13 and 13 must have a sufficient lateral distance from lever 3.

At the occurrence of an overload, the thermal overload release works as follows:

From the fixed contact members 11 the overload current flows through a bimetal strip or blade 24. When this strip 24 is heated up, it curbs and its upper end moves to the left in FIG. 1. By means of a slider 25 the pawl 8 is also pulled to the left and the lever 3, which carries the movable contact member 4, is freed. Under the influence of the spring 9 lever 3 pivots in anticlockwise direction and the lower end of the movable contact member 4 moves to the right. Thus, the circuitbreaker opens.

The current also flows through the windings 23 of a magnetic short-circuit release 16. In case of a shortcircuit, the magnetic excitation of the short-circuit release 16 is sufficient to attract the movable armature 20 and to move it to the right in FIG. 1. By this a pivotably arranged finger 22 is turned and pushes the pawl 8 to the left, which frees the lever 3 as before. At the same time an axially movable pin 21 at the other end of the armature 20 knocks on the movable contact member 4 and accelerates it much more than the spring 9 could do it alone. Therefore the contact members are separated very quickly from each other.

When the breaker mechanism has been released by disengaging the pawl 8 andprovided the handle is not held back by hand, a weak spring (not shown in the drawing) pulls the handle 5 into the open position (as shown in FIG. 1). By this movement the levers 2, 2' are turned downwards and the pawl 8 engages again with lever 3. The breaker is now ready to be closed again by manual operation of the handle 5.

What we claim is:

1. An electrical circuit-breaker comprising a housing, fixed and movable contact members and a breaker mechanism for actuating the movable contact member, said breaker mechanism including a pivotable handle for manual operation of the breaker, a first axle fixed in the housing, a first lever with two arms of unequal length, said lever being pivotably supported by said axle and being operatively connected with said handle in direction of closing the breaker by the handle, and a coil spring arranged on said axle for urging said lever in a direction to open the contacts, characterized by the fact, that the first axle carries also a second lever having a slot mechanically engaged with the handle, that the two arms of the first lever stand nearly at an angle of to each other, the summit of the angle coinciding almost with the axle and that the movable contact member is mounted on the shorter arm of the first two armed lever.

2. A circuit-breaker according to claim 1, in which the second lever having a slot is coupled, in its direction of movement for closing the contacts, with the first lever by a pawl capable of engaging the longer arm of said first lever.

3. A circuit-breaker according to claim 2, which is equipped with two second' levers with slots, between which the pawl is pivotably suspended.

4. A circuit-breaker according to claim ll, wherein the movable contact member is pivotably connected to the shorter arm of the first lever by means of a second axle and has a backward extension extending beyond said second axle, the spring having a middle outwardly extended leg which presses on the backward extensions of the movable contact member, the two halves of the spring on opposite sides of the middle leg being wound in opposite senses.

5. A circuit-breaker according to claim 1, wherein the movable contact member is pivotably connected to the shorter arm of the first lever by means of a second axle and has a backward extension extending beyond said second axle, two coil springs being carried by the first axle, each of said springs having outwardly extended end portions, the neighbouring one of which press on the backward extensions of the movable contact member.

6. A circuit-breaker according to claim 4, wherein the second axle carrying the movable contact member has sufficient play in the first lever and the movable contact member has sufficient lateral distance from the first lever to permit the movable contact member to be rocked arround its length direction over at least 210 during closing motion of the movable contact member.

7. A circuit-breaker according to claim 1, wherein the first lever carries two movable contact members which are electrically connected by a flexible connection.

Claims

1. An electrical circuit-breaker comprising a housing, fixed and movable contact members and a breaker mechanism for actuating the movable contact member, said breaker mechanism including a pivotable handle for manual operation of the breaker, a first axle fixed in the housing, a first lever with two arms of unequal length, said lever being pivotably supported by said axle and being operatively connected with said handle in direction of closing the breaker by the handle, and a coil spring arranged on said axle for urging said lever in a direction to open the contacts, characterized by the fact, that the first axle carries also a second lever having a slot mechanically engaged with the handle, that the two arms of the first lever stand nearly at an angle of 90* to each other, the summit of the angle coinciding almost with the axle and that the movable contact member is mounted on the shorter arm of the first two armed lever.

3. A circuit-breaker according to claim 2, which is equipped with two second levers with slots, between which the pawl is pivotably suspended.

4. A circuit-breaker according to claim 1, wherein the movable contact member is pivotably connected to the shorter arm of the first lever by means of a second axle and has a backward extension extending beyond said second axle, the spring having a middle outwardly extended leg which presses on the backward extensions of the movable contact member, the two halves of the spring on opposite sides of the middle leg being wound in opposite senses.

6. A circuit-breaker according to claim 4, wherein the second axle carrying the movable contact member has sufficient play in the first lever and the movable contact member has sufficient lateral distance from the first lever to permit the movable contact member to be rocked arround its length direction over at least + or - 10* during closing motion of the movable contact member.