US3239638A - Circuit breaker device including stop means for limiting contact arm movement - Google Patents

Description

March 1966 c. E. GRYCTKO ETAL 3,239,633

CIRCUIT BREAKER DEVICE INCLUDING STOP MEANS FOR LIMITING CONTACT ARM MOVEMENT Filed Jan. 24, 1964 4 Sheets-Sheet l 3 I NVENTORS 457 201 EMA, 76459, 514a? fJkF/Em l L's-.51

March 8, 1966 Filed Jan. 24, 1964 C. E. GRYCTKO ETAL CIRCUIT BREAKER DEVICE INCLUDING STOP MEAN FOR LIMITING CONTACT ARM MOVEMENT 4 Sheets-Sheet 2 INVENT RS oaez 5. 62 74 0 Filed Jan. 24, 1964 7' if g 50 C. E. GRYCTKO ETAL CIRCUIT BREAKER DEVICE INCLUDING STOP MEAN FOR LIMITING CONTACT ARM MOVEMENT 4 Sheets-Sheet 3 March 8, 1966 c. E. GRYCTKO ETAL 3,239,638

CIRCUIT BREAKER DEVICE INCLUDING STOP MEANS FOR LIMITING CONTACT ARM MOVEMENT 4 Sheets-Sheet 4 Filed Jan. 24, 1964 JAE-.5.

United States Patent 3,239,638 CIRCUIT BREAKER DEVICE INCLUDING STOP MEANS FOR LIMITING CONTACT ARM MOVEMENT Carl E. Gryctko, Haddon Heights, N.J., and John C. Brumfield, Philadelphia, Pa., assiguors to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed Ian. 24, 1964, Ser. No. 340,036 11 Claims. (Cl. 200-166) This invention relates to circuit breakers in general and more particularly to molded case case circuit breakers of very compact construction having novel means for limiting movement of contact arm as the circuit breaker is opened.

In molded case multi-phase circuit breakers of even modest current carrying capacity quick-make and quickbreak features are incorporated. Thus, a circuit breaker of this type is provided with a relatively strong main operating spring. Further, in a circuit breaker of this type, constructions are especially compact so that there is very little room for the incorporation of shock absorbing means for cushioning the contact arm as the contacts are operated into and out of engagement. This invention is concerned primarily with the shock absorbing means which cushions the contact arm as the circuit breaker is operated to open position.

The contact arm is an elongated member which carries the movable contact at one end thereof and is pivotally mounted near the other end thereof to a contact carrier. The carrier, in turn, is mounted to the mechanism for operating the contacts into and out of engagement. Upon opening of the contacts, the relatively great amount of energy stored in the main spring of the operating mechanism must be expended in a very short travel of the carrier and the contact arm carried thereto.

Typically, shock absorption in this area is accomplished by providing a cantilevered leaf spring which also acts to maintain contact pressure. This spring is fixedly secured to the carrier and is operatively positioned in the path of the contact arm to be engaged thereby as the circuit breaker is opened. That is, the spring is so positioned that when the carrier stop moves in the opening direction for the circuit breaker, the contact arm being pivotally mounted to the carrier continues to move in the opening direction with the engagement with the spring serving to gradually arrest this movement.

Engagement between the contact arm and the spring takes places at one end of the contact arm and at the free end of the cantilevered spring, Should the circuit breaker operating spring be especially strong or should opening occur at the precise moment when an external force acts upon the contact arm in the opening direction the spring may be deflected to such an extent that the end of the contact arm moves past the end of the spring thereby maintaining the contact arm in such a position that the spring will be ineflFective to exert contact closing pressure when the circuit breaker is thereafter closed.

In order to overcome this problem, the circuit breaker of the instant invention is provided with a stop which limits the deflection of the spring as the movable contact arm moves toward open circuit position. This stop is advantageously constructed as an extension of the conventional rivet plate provided to relieve stresses at the area of the leaf springs through which the securing rivets extend.

For some applications the rivet plate may be advantageously constructed of relatively stilf spring material. This, in effect, provides a two-stage spring for arresting movement of the contact arm as the circuit breaker is opened.

Accordingly, a primary object of the instant invention is to provide novel contact arm shock absorbing means for the operating mechanism of a molded case circuit breaker.

Another object is to provide novel shock absorbing means of this type which is active as the circuit breaker is opened.

Still another object is to provide a novel shock absorbing means of this type which is so constructed as to limit the movement of the contact arm on opening the circuit breaker to a position which will enable subsequent closing operations to be performed satisfactorily.

A further object is to provide novel shock absorbing means of this type having a stop means to limit movement of the free end of a cantilevered spring means.

A still further object is to provide novel shock absorbing means of this type in which the stop is constructed of relatively stiff spring material so that the stop means acts in conjunction with the cantilevered contact pressure spring to produce a two-stage shock absorber.

These as well as further objects of the instant inven tion shall become readily apparent after reading the following description of the accompanying drawings in which:

FIGURE 1 is a plan view of a circuit breaker constructed in accordance with the teachings of the instant invention with substantially all of the cover broken away to reveal the internal mechanism.

FIGURE 2 is a longitudinal cross-section taken through line 2-2 of FIGURE 1 looking in the direction of arrows 22.

FIGURE 3 is a plan view illustrating the contact arm mounted to its carrier.

FIGURE 4 is a cross-section taken through line 4-4 of FIGURE 3 looking in the direction of arrows 4-4.

FIGURE 5 is an end View of the elements of FIGURE 3 looking in the direction of arrows 55 of FIGURE 4.

FIGURE 6 is a bottom view of the elements of FIG URE 3 looking in the direction of arrows 6-6 of FIG- URE 4.

FIGURES 7 through 9 are side elevations illustrating the relationship between the contact arm, its carrier and the stationary contact for various operating conditions of the circuit breaker. In FIGURE 7 the circuit breaker is fully closed; in FIGURE 8 the circuit breaker is fully opened; and in FIGURE 9 the contact arm has rotated past its normal open position during the opening operation of the circuit breaker.

Now referring to the figures. Circuit breaker 10 is a three-phase molded case unit of the type illustrated in copending application Serial No. 108,812 filed May 9, 1961 now Patent No. 3,155,802 in the name of E, Wortrnann entitled U-Shaped Cradle for Circuit Breaker and assigned to the assignee of the instant invention. Briefly, circuit breaker 10 is provided with a molded housing consisting of base 11 and cover 12 joined at line 13. Transverse partitions 11a, 11b cooperate with similar longitudinal partitions (not shown) of cover 12 to divide housing 11, 12 into three longitudinal compartments, one for each phase of circuit breaker 10.

The current path for each phase of circuit breaker 10 is identical. Thus, for the sake of brevity, only one of these current paths will be described with reference to FIGURE 2. This current path proceeds from line terminal connector 24, bushing 24a, line terminal strip 14, stationary contact 15, movable contact 16, contact arm 17, split flexible braid 18, bracket 19, inverted U-shaped bimetal heater 20, magnetic trip means winding 21, and load terminal connector 22.

Mechanism 23, disposed in the center compartment of housing 11, 12, is provided to simultaneously operate the cooperating contacts 15, 16 of each phase into and out of engagement, in a manner well known to the art. Also in a manner well known to the art, circuit breaker is provided with an individual automatic trip unit 25 for each phase thereof. Since operating mechanism 23 and trip unit 25 form no part of this invention, and the prior art contains many teachings of circuit breaker operating mechanisms and automatic trip units suitable for the instant application, they will not be described in detail.

The invention concerns itself with the mounting of contact arm 17. Frame 30 is of a generally U-shaped at the rear 31 thereof with the arms of the U being notched to receive insulating tie bar 33. Clamp plate 32 is provided with a plurality of apertures which receive extensions 31a projecting upwardly from the rear 31 of frame 30'. The free ends of extensions 31a are deformed thereby fixedly securing plate 32 to frame 30 and in so doing fixedly securing frame 30 to tie bar 33.

Frame 30 is also provided with parallel arms 34a and 34b which extend forwardly from the rear 31 of frame 30. Pin 35 extends between arms 34a, 341) at the forward ends thereof and extends through aperture 36 to contact arm 17 formed by displacing portions of contact arm 17 in opposite directions. Thus, it is seen that pin 35 provides a pivotal mounting for contact arm 17 relative to frame 30.

Movable contact 16 is mounted at the forward end of contact arm 17 while the convex portion 41 of arm 17 to the rear of pivot pin 35 is engaged by the free end of spring assembly 42. Assembly 42 consists of a plurality of cantilevered leaf springs secured at one end thereof to frame 30 by means of rivets 43. Rivets 43 extend through the web portion of frame section 31, through the plurality of leaf springs constituting spring assembly 42, and through rivet plate 44 provided with forward extension 44a, for a purpose to be hereinafter explained.

As is well known to the art, tie bar 33 extends transversely across circuit breaker housing 11, 12 and is connected to the frames 30 of all three phases. Also in a manner well known to the art, pin 47 (FIG, 2) extends through aperture 48 in arms 34a, 34b of the center phase frame 30 to operatively connect operating mechanism 23 for simultaneously operating the cooperating contacts of all three phases into and out of engagement.

As seen in FIGURE 7, with circuit breaker 10 closed, main operating springs 49 of mechanism 23 bias movable contact 16 into firm engagement with stationary contact 15. In so doing, there is movement of contact arm 17 relative to frame 30 in a counterclockwise direction about pin 35 in the center. This causes end 41 of contact arm 17 to slightly deflect the contact pressure springs assembly 42.

With circuit breaker 10 in the fully open position of FIGURE 8, springs 42 urging contact arm 17 in a clockwise direction about pin 35 driving the tip of end portion 41 against stop 51 formed integrally with frame 30 and extending forwardly from the web portion at the rear section 31 of frame 30.

During the opening operation of circuit breaker 10, contact arm 17 moves very rapidly from the position of FIGURE 7 to the position of FIGURE 8. Under these circumstances, the inertia of movable contact 16 causes contact arm 17 to pivot counterclockwise from its position of FIGURE 8. Under ordinary circumstances, this movement will be arrested by spring assembly 42 before assembly 42 engages portion 44a of rivet plate 44. However, under extremely adversely operating conditions, as when circuit breaker 10 is subjected to internal magnetic blow off forces or interruption external shock forces during the opening operation, the deflection of spring assembly 42 is suflicient to bring it in engagement with rivet plate extension 44a.

As seen in FIGURE 9, rivet plate extension 44a is so positioned that contact arm end 41 remains in engagement with spring assembly 42 even when spring assembly 42 is deflected to its maximum position in engagement with rivet plate extension 44a. It is noted that in prior art constructions rivet plate 44 was not provided with an extension 44a to limit the deflection of springs 42. When rivet plate extension 44a is not present, contact arm 17 would often rotate so much in a counterclockwise direction that contact arm end 41 will move past the forward tip of spring assembly 42. Under these circumstances the next closing operation of the circuit breaker will be ineffectual to bring movable contact 16 into engagement with stationary contact 15.

Thus, it is seen that rivet plate extension 44a serves as a stop to limit deflection of contact pressure springs 42 during the opening operation of circuit breaker 10. It is noted that rivet plate 44 is provided to alleviate stress at the rivet holes in the springs of assembly 42 so that the provision of extension 44a adds only negligibly to the cost of circuit breaker 10. Plate 44 is constructed of relatively stiff material so as to act as a positive stop. For some applications it may be desirable to construct rivet plate 44 of spring material which is much stiffer than the leaves of assembly 42. This produces a two-stage spring action resulting in a more gradual decelleration of contact arm 17.

Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited, not by the specific disclosure herein, but only by the appended claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. A circuit breaker including a pair of cooperating contacts, a contact arm carrying one of said contacts, a frame carrying said arm, an operating mechanism connected to said frame for operating said contacts between an open and a closed position, spring means secured to said frame and in operative engagement with a free end of said arm urging said contact arm in a first direction to exert contact closing pressure when said circuit breaker is closed, said spring means positioned to engagingly arrest the movement of said contact arm free end when said circuit breaker is being opened, and said contact arm is moving in a second direction opposite to said first di rection, said contact arm movable in said second direction to an extended position, beyond said open position, where the biasing effect of said spring means is defeated, stop means carried by said frame and operatively positioned to limit and prevent movement of said contact arm to said extended position.

2. A circuit breaker as set forth in claim 1 in which the stop means is positioned in the path of said spring means to limit deflection thereof when said circuit breaker is being opened.

3. A circuit breaker as set forth in claim 2 in which the spring means is a cantilevered leaf unit.

4. A circuit breaker as set forth in claim 3 in which there is an anchoring means securing one end of said leaf unit to said frame and positioning the other end of the leaf unit in engagement with one end of said contact arm, said one contact being mounted at the other end of said contact arm.

5. A circuit breaker including a pair of cooperating contacts, a contact arm carrying one of said contacts, a frame carrying said arm, an operating mechanism connected to said frame for operating said contacts between an open and a closed position, spring means secured to said frame and in operative engagement with said arm urging said contact arm in a first direction to exert contact closing pressure when said circuit breaker is closed,

stop means carried by said frame and operatively positioned to limit movement of said contact arm in a second direction opposite to said first direction when said circuit breaker is being opened, said stop means positioned in the path of said spring means to limit deflection thereof when said circuit breaker is being opened, said spring means being a cantilevered leaf unit, in which there is an anchoring means securing one end of said leaf unit to said frame and positioning the other end of the leaf unit in engagement with one end of said contact arm, said one contact being mounted at the other end of said contact arm, in which said one end of said contact arm presents a convex surface engaged by said other end of the leaf unit.

6. A circuit breaker including a pair of cooperating contacts, a contact arm carrying one of said contacts, a frame carrying said arm, an operating mechanism connected to said frame for operating said contacts between an open and a closed position, spring means secured to said frame and in operative engagement with said arm urging said contact arm in a first direction to exert contact closing pressure when said circuit breaker is closed, stop means carried by said frame and operatively positioned to limit movement of said contact arm in a second direction opposite to said first direction when said circuit breaker is being opened, in which the stop means is positioned in the path of said spring means to limit deflection thereof when said circuit breaker is being opened, said spring means being a cantilevered leaf unit, in which there is an anchoring means securing one end of said leaf unit to said frame and positioning the other end of the leaf unit in engagement with one end of said contact arm, said one contact being mounted at the other end of said contact arm, in which there is a pivot means intermediate the ends of said contact arm securing said contact arm to said frame.

7. A circuit breaker as set forth in claim 6 in which the anchoring means includes a plate having a portion constituting said stop means.

8. A circuit breaker as set forth in claim 7 in which the frame includes an integrally formed portion positioned for engagement by said one end of said contact arm to limit movement of said contact arm in said first direction relative to said frame.

9. A circuit breaker as set forth in claim '7 in which the plate is constructed of rigid material.

10. A circuit breaker as set forth in claim 7 in which the plate is constructed of spring material.

1.1. A circuit breaker as set forth in claim 10 in which the spring material is of substantially greater stiffness than said leaf unit.

References Cited by the Examiner UNITED STATES PATENTS 3,014,103 12/1961 Moran et a1 200-166 X 3,158,716 11/1964 Koval 200116 KATHLEEN H. CLAFFY, Primary Examiner. BERNARD A. GILHEANY, Examiner.

Claims (1)

1. A CIRCUIT BREAKER INCLUDING A PAIR OF COOPERATING CONTACT, A CONTACT ARM CARRYING ONE OF SAID CONTACTS, A FRAME CARRYING SAID ARM, AN OPERATING MECHANISM CONNECTED TO SAID FRAME FOR OPERATING SAID CONTACTS BETWEEN AN OPEN AND A CLOSED POSITION, SPRING MEANS SECURED TO SAID FRAME AND IN OPERATIVE ENGAGEMENT WITH A FREE END OF SAID ARM URGING SAID CONTACT ARM IN A FIRST DIRECTION TO EXERT CONTACT CLOSING PRESSURE WHEN SAID CIRCUIT BREAKER IS CLOSED, SAID SPRING MEANS POSITIONED TO ENGAGINGLY ARREST THE MOVEMENT OF SAID CONTACT ARM FREE END WHEN SAID CIRCUIT BREAKER IS BEING OPENED, AND SAID CONTACT ARM IS MOVING IN A SECOND DIRECTION OPPOSITE TO SAID FIRST DIRECTION, SAID CONTACT ARM MOVABLE IN SAID SECOND DIRECTION TO AN EXTENDED POSITION, BEYOND SAID OPEN POSITION, WHERE THE BIASING EFFECT OF SAID SPRING MEANS IS DEFEATED, STOP MEANS CARRIED BY SAID FRAME AND OPERATIVELY POSITIONED TO LIMIT AND PREVENT MOVEMENT OF SAID CONTACT ARM TO SAID EXTENDED POSITION.

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