US2427998A - Circuit breaker - Google Patents

Description

Sept. 23, 1947.

K. W. WILCKENS CIRCUIT BREAKER Filed March 27, 1942 IN VEN TOR I ATTORNEY Patented Sept. 23, 1947 UNITED STATES PATE'NT O FFlCE Kurt W. Wilckens, Morrisville, Pa., assignor Heinemann Electric Company, Trenton, N. 1.,

a corporation of New Jersey Application March 27,1942, Serial No. 436,467

5 Claims. (Cl. 200-109) My invention is a trip free circuit breaker having complementary contacts one of which is movable and controlled by tripping mechanism including a member having an axis of inertia and which is rendered substantially immune to tripping by means substantially neutralizing moments of force which dynamic action on said matic circuit breakers by shocks or dynamic action, such as results from forces suddenly producing, changing, or preventing motion, as, for example, from diving, zooming and maneuvering airplanes, from impacting tanks against obstacles, or from driving automobiles over rough roads and boatsover rough water.

My improvements are primarily applicable to circuit breakers in which the tripping mechanism, through which the movable contact is controlled, embodies one or more members rockable on an axis responsively to current changes and having an axis about which moments act and herein sometimes referred to as inertia axis or of inertia substantially coincident with such rocking axis. Dynamic forces; resulting from momentum, inertia and the like, tend to rocksuch members on their axes and trip the breaker. In accordance with my invention, the deleterious effects of such dynamic forces are neutralized by the provision of counterbalances or counteractants acted upon by the dynamic forces to produce moments of force opposite to and counteracting the moments of force imparted by the dynamic forces to the rocking members utilized in tripping.

The tripping mechanism preferably comprises a current-responsive trigger and connecting rod latch operable .by the trigger, though the trigger may act directly on the connecting rod when the It is preferable that both trigger and latch be counterbalanced, but the counterbalancing of the former is generally of greater importance due to its greater susceptibility to displacement owing to its greater mass and lesser frictional resistance to rocking.

My improvements are especially adapted for incorporation in a circuit breakers'uch as set forth in my co-pending application Serial No. 266,316 which is instantaneously tripped upon 2 the occurrence of a short circuit but permits continuous flow of current, when the breaker is closed, up to slight harmless overloads of say 125% of rated capacity but which will effect tripping within a timeinverse to magnitude of harmful overloads As set forth in such application, tripping is effected through an armature having a finger connected therewith and fixed on a journaled shaft. In accordance with the present invention such shaft also carries a pair of counterbalancing arms at the ends thereof. The mass, shape and location of the armature, finger and counterweigh'ts are so corelated that the shaft is statically balanced and the effects of dynamic forces on the armature, finger and counterweights neutralize one another.

'The trigger acts on an arm of a trip shaft which -has .a counterweight projecting therefrom oppositely to and balancing the arm so that dynamic forces acting on the .arm and tending to turn the shaft to tripping position are neutralized by the action of like forces on the counterweight;

The characteristic features and-advantages ofmy invention will further appear from the following description and the accompanying drawings in illustration thereof.

In the drawings, Fig. 1 is a vertical sectionalview through a circuit breaker housing showing in part sectional elevation the operating parts of a preferred embodiment of my invention; Fig. 2 is an irregular vertical sectional view taken approximately on the line 22 of Fig. 1; Fig, 3 is a perspective view of a statically balanced current-responsive trigger mechanism comprised in my invention; Fig. 4 is a part sectional side elevation of trigger mechanism shown in Fig. 3 in operative relation with a diagrammatically illustrated electro-magnet; Fig. 5 is a perspective view of counterbalanced link-latching mechanism comprised in my invention; and Fig. 6 is'a longitudinal sectional view of the link-latching mechanism shown in Fig. 5.

In the embodiment of myiinventio'n illustrated in the drawings, my improvements are incorporated in a type of automatic circuit breaker' shown in my application .Serial No. 266,316 filed April 6, 1939, to which reference is made for a detailed description of the construction and operation of the circuit breaker per se.

Briefly it comprises a rigid switch blade I which is shiftably mounted on a shiftable fulcrum pin 2 seated in slotted ears 3 of a magnetically permeable frame 4; the blade being normally biased contact 6.

3 by a spring 5 toward open position away from a Frame ears I have journaled therein the axle 8 of a rotatable operating-handle 9. The handle 9 is operatively connected with an intermediate portion of the switch blade I through a jointed connecting rod comprising links l and H respectively provided with complementary latching members i2 and I3 which, when interlocked with one another, make rigid the joint of the connecting rod.

The links l0 and H of the connecting rod are pivotally connected wlth one another by the pin I4 and with the blade I and handle 4 by the pins l5 and i6 respectively.

The latching member l2 comprises an integral tooth on the link l0 adjacent to the pin I4 and the complementary latching member 13 comprises a shaft having cylindrical end sections journaled in spaced webs of the link ll. Between the link webs, a segmental intermediate section of the shaft 13 is cut away to provide a notch ll whose bottom is a chord of the shaft to permit passage of the tooth l2 when the shaft l 3 is turned on its axis to bring the notch ll into registration with the tooth I2.

In accordance with the present invention,

spokes l8 and 19 project in opposite directions from an end of the shaft 13 on radii substantially parallel with the chord defining the bottom of the notch H. The spoke 19 has a bent end 20 inturned through a slot 2| in a web of the link H and normally biased toward one end of the slot by a spring 22. y

While the spoke end 20 is biased toward the lower end of the slot 2|, the tooth l2 engages a circumferential portion of the shaft [3 and prevents collapse of the joint between the links I0 and H, but when the spoke end 20 is moved toward the other end of the slot 2| it turns the shaft l3 so as to permit the movement of the tooth I2 through the notch ll, with consequent collapse of the joint between the links l0 and II. The spoke I8 is of such Weight, length and shape that it provides an effective counterbalance for the spoke I9 and counteracts or neutralizes the torque which would otherwise be applied to the shaft I3 by the spoke [8 as a result of deceleration or change of direction of movement of the switch in a direction transverse to the chord bounding the bottom of the notch IT.

The latch arm l9'is, however, operable to permit the collapse of the connecting-rod joint by current-responsive trigger mechanism comprising an L-shaped member forming an armature 24 and finger 25 connected, through lugs 26, with the shaft 21, which is journalled in the ears I. In accordance with my present invention, weighted arms or spokes '28 are fixed to the ends of the shaft 21 to counterbalance the spokes formed by the armature 24 and finger 25.

When the blade I is closed, the finger 25 projects beneath the member 20 and lies in posi tion to rock the latter when the armature 24 is attracted against the face of the pole-piece 29 of an electro-magnet 30 energized by current flowing through the contacts I and B, as described,

in my previous application.

The spokes formed by the armature 24, finger 25 and arms 28 are of such weight and length and are so positioned relatively to one another as to statically balance the shaft 21 on its axis, which is substantially coincident with the axis of inertia of this spoke assembly. Each of these spokes tends to neutralize the torque which would be applied by the others to the .shaft 21 as a result of shock to, deceleration, acceleration, or change in direction of movement of the circuit breaker. In other words, whatever torque is applied to the shaft 21 by the effect of momentum or inertia on one spoke is counteracted by a counter-torque applied to the shaft 21 by the effect of the momentum or inertia on another spoke or spokes.

It will be understood that when a distributed force, such as that produced by sudden stoppage or change of movement, is exerted on a statically unbalanced device freely movable on an axis. it produces a tendency to turn or rotate the unbalanced device about such axis in the direction of the greater moment of force computed with reference to such axis, and the tendency to r0- tate is proportional to the resultant moment of force. In accordance with my improvements, the parts 24, 25 and 28 of the trigger assembly are so balanced about its axis as to produce a condition of equilibrium, with no tendency to turn, since moments of force, which dynamic action tends to impart to the member 24, even when such action is along a line intersecting the axis 2'! diagonally to the member 24, is neutralized by the members 25 and 28. Where complete equilibrium is impracticable the resultant of the sum of the moments of force may tend to slightly bias the armature away from rather than toward the electro-magnet and thereby supplement the action of the spring 3|.

Preferably the positions of the centers of gravity of the spokes and the angles of each in relation to the other in both the trigger assembly and the latch assembly is such that the sum of the moments of the various parts of each assembly equals zero, producing equilibrium comparable to that of a balance wheel so that, if a distributed force is exerted on the spokes of either assembly it will not appreciably disturb their positions about their respective axes, for, since the parts are in balance, there is no tendency for them to turn about their axes.

Consequently the circuit breaker is automatically responsive solely to changes in current, which changes in current act on the circuit breaker independently of the effects of momentum or inertia resulting from travel of the circuit breaker or shocks imparted thereto by impact or otherwise.

While I have described the application of my invention to a form of arrester shown in my co-pending application Serial No. 266,316, filed April 6, 1939, the principles thereof are equally applicable to the circuit breakers shown in my patents Nos. 2,200,109, 2,200,108, 2,072,932, 1,960,- 402, or any circuit breaker in which current control of a switch contact is transmitted through tripping mechanism having an unbalanced arm movable about an axis by a moment of inertia or momentumv Having described my invention, I claim:

1. \An automatic trip-free circuit breaker having complementary contacts, one of which is movable relatively to the other, and mechanism controlling movements of said movable contact and including a link movable with said movable contact, a latching shaft carried by said movable link. an arm projecting transversely from such shaft, a counterweight for said arm, a trigger [for rocking said arm, and 'a link connected with said first link and having a member complementary to said shaft.

2. An automatic trip-free circuit breaker having complementary contacts, one -oi. which is movable relatively to the other, and mechanism controlling the movement of said movable contact and including a shaft, an armature and trigger connected with said shaft between the 5 ends thereof, and a counterbalance for said armature and trigger connected with an end of said shaflt beyond the connection of said armature and trigger therewith, said armature, trigger and counterbalance substantially neutralizing the turning tendencies of one another under dynamic action.

3. A trip-free circuit breaker having complementary contacts, one of which is movable relatively to the other, and mechanism controlling movements of said movable contact andincluding a shaft with at least three spokes thereon forming an armature, a trigger and counterbalances for the armature and trigger, a latch operable by said trigger and including a shaft 2() having spokes thereon one of which is actuated by said trigger and the other of which forms a counterbalance disposed between the counterbalances first named said last named spokes substantially neutralizing the turning tendency of one .another, and a cooperating element complementary to said latch.

4. The combination with. a movable switch member and an operating handle therefor, of a plurality of rocking links respectively pivotally 1,701,440

connected with the member and handle, one ofsaid links having a latching element connected therewith, a rocking latching element iournalled in'and movable with one of the links and cooperating with the element first named, and a statically balanced unit connected with said rocking element restraining rocking thereofirom shock whether or not said elements are latched together.

5. The combination with a frame, of a movable switch member fulcrumed on said frame, a pivotally mounted mechanism mounted on said frame in spaced relation to said switch member and having spokes projecting outward in at least three directions, pivotally connedted links one of which is connected with and controls said switch member, acurrent responsive device operatively associated with one of said spokes dor rocking said mechanism, and a latch controlling said links and operatively associated with another of said spokes, another of said spokes tending to neutralize turning movements applied to said mechanism by dynamic action on said first named spokes.

KURT W. WIIJCKENS.

REFERENCES CITED The following references are of record in the a Number Name Date 570,212 Wurts Oct. 27, 1896 Chatto Feb. 5, 1929 2,067,797 Smith Jan. 12,1937 2,178,083 Sandin Oct. 31, 1939 Y 1,887,274 Mayer Nov. 8, 1932

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