US3061702A - Movable switch member - Google Patents

Description

Oct.

30, 1962 c. L. JENCKS MOVABLE SWITCH MEMBER Filed Oct. 10; 1960 IN V EN TOR.

Charles L. Jencks By W M112 7 Attor-ng;

the inner ends of the contact and switch arms.

United States Patent 3,061,702 MOVABLE SWITCH MEMBER Charles Louis Jencks, Avon, Conn., assignor to General Electric Company, a corporation of New York Filed Oct. 10, 1960, Ser. No. 61,718 2 Claims. (Cl. 200146) This invention relates to an electric circuit interrupter, and more particularly, to an electric circuit interrupter incorporating a contact structure wherein the movable contacts are resiliently mounted to provide desirable en gagement and disengagement with cooperating fixed contacts.

In electric switch apparatus of the type wherein movable contact means are movable by a rocking or pivoting action into engagement with fixed contact means, the problem is encountered of providing a measure of resiliency between the cooperating contact means so as to insure firm face-to-face abutment of the respective cooperating contacts. For this purpose it has been customary to provide a relatively free-floating member carrying the movable contacts, mounted upon a member which can be moved between circuit-open and circuit-closed positions. This resiliency affords a degree of compensation or adjustment in the attitude of the contact-carrying member to permit desired abutment along the entire surface of the face-to-face contacts. The design and construction of such a resiliently mounted contact-carrying member in turn raises problems of insuring simplicity, compactness, and reliability. These problems are compounded when it is desired to incorporate in such a structure a dual contact arrangement characterized by sequential opening, or the type of opening wherein one pair of contacts is made or broken in sequence with a second pair of contacts. A still further problem arises from the fact that the relatively movable resiliently mounted contact-carrying member must be connected in some way to relatively fixed terminals of its associated circuit.

The object of this invention is to provide an improved contact structure for an electric circuit interrupter.

Another object is to provide an electric circuit interrupter having improved means for resiliently mounting first contact means movable into and out of engagement with second contact means.

Still another object is to provide an electric circuit interrupter having two pairs of contacts adapted for sequential opening and closing, wherein the movable contact structure is resiliently mounted for firm abutment with the fixed contact structure.

Still another object is to provide an electric circuit interrupter having a resiliently mounted contact-carrying structure incorporating a reliable means for connecting the movable contact into the associated circuit.

In accordance with the invention in one form, a switch structure is provided with a movable switch arm of generally U-shaped channel cross-section having pivotally connected to an outer end thereof a movable contact arm located within the channel of the switch arm. The movable contact arm carried by the switch arm is pivoted at one end nearest the pivoting point of the switch arm by a pivot pin and aperture arrangement while the outer end of the contact arm is loosely connected to the switch arm through a pin and slot arrangement which thereby provides somewhat greater relative movement of the outer end of the contact arm relative to the switch arm than Resilient means is interposed between the switch arm and contact arm to normally urge the two arms apart within limits controlled by the aforementioned pivot means.

In the arrangement of the invention described above, the contact arm may be provided with a single contact at 3,061,702 Patented Oct. 30, 1962 its outer end or it maybe provided with dual contacts respectively positioned near the inner and outer ends of the contact arm. With the use of dual contacts, various arrangements of fixed contacts may be employed and wired to respective terminals to provide various functions, such as a current by-pass for the connections between the fixed terminal and the movable contact arm or arcing contacts as may be obtained due to, an inherent sequential opening of the dual contacts when the movable contact arm arrangement of the invention is actuated.

Further objects, features, and attending advantages of the invention will become apparent by reference to the following specification and drawings, in which:

FIGURE 1 is a cutaway view of a circuit interrupter incorporating the invention;

FIGURE 2 is a fragmentary view taken along line 22 of FIGURE 1;

FIGURE 3 is a fragmentary view of a modified form of the invention incorporating a dual-contact, sequentially opening structure;

FIGURE 4 is a partial view of still another embodiment of the invention.

With reference to FIGURE 1, the invention is shown as incorporated in an electric circuit breaker including a housing, generally indicated at 1 containing operating mechanism actuated by a toggle handle 2 of the wellknown type. Toggle handle 2, by means of a system of linkages which may be of any well-known type not shown, causes the pivoting of a switch arm 3 about a pivot shaft 31. The pivot shaft 31 may mount the switch arm 3 in any convenient fashion and, as best illustrated in FIGURE 3, may take a well-known form comprising the metallic shaft 31 of square cross-section, surrounded by electric insulating material 32. A deformable metallic band 33 surrounds the insulating material 32, is passed through apertures in the body of the switch arm 3, and is formed over or peened, thereby rigidly securing switch arm 3 to the rotatable pivot shaft 31.

As seen in FIGURE 2, switch arm 3 is of U-shaped cross-section, having parallel side walls 34. As best shown in FIGURE 3, there are fixed between and transversely to the parallel side walls 34 a first pin 35 and a second pin 36.

A contact arm 4 is disposed between the parallel side walls 34 of the actuating member 3. Referring to FIG- URE 3, wherein one side wall 34 of switch arm 3 is cut away to reveal the contact arm 4, there is shown an aperture 45 at one end of the arm, and a slot 46 at the other end. Pin 35 passes through aperture 45, and pin 36 passes through slot 46.

Spring means are provided to bias apart switch arm 3 and contact arm 4, comprising a helical coil spring 5, arranged to be in compression. As illustrated in FIG- URE 1, parallel slots 34 are provided in each parallel side wall 34 of the switch arm 3. These slots 37 are aligned with and parallel to the axis of the helical spring 5, and act as a guide for the spring while also permitting a larger spring to be used within the relatively narrower space afforded between the parallel side walls 34.

Carried at the end of arm 4 corresponding with slot 46, is a movable contact 6. In the closed-circuit condition, contact 6 abuts against fixed contact 61. At the end of arm 4 corresponding with aperture 45 there is attached a flexible conductor 7. In the preferred embodiment of this invention, conductor 7 takes the form of a braid type conductor.

Fixed contact 61 is in electrical connection with a terminal 62, which is in turn electrically connected to a conductor 63 in the circuit on one side of the switch. The flexible conductor 7 is electrically connected with a terminal 82, which is in turn electrically connected to a conductor 83 on the side of the switch opposite conductor 63. Thus, in the embodiment illustrated in FIGURE 1, flexible conductor 7 completes the circuit between arm 4 and its associated contacts 6, 61 on one side and terminal and conductor 82 and 83 on the other side. Such a flexible conductor is necessary due to the floating or resilient mounting of the contact arm 4. The resilient mounting of arm 4 insures uniform contact along the entire surface between movable contact 6 and fixed contact 61. Spring 5, urging the end of arm 4 which carries contact 6 in a counter-clockwise direction about pivot pin 35, results in the firm abutment of contacts 6, 61, despite slight displacement of the actuating member 35 about its pivot 31, so long as that displacement does not exceed the limits defined by the upper and lower extremities of slot 46. It is further apparent that the construction thus provided will alford inherent compensation for slight wear upon the contacts 6, 61, whereby uniform abutment along the surfaces of the contacts will be maintained in spite of the somewhat lower attitude which contact arm 4 will assume in the contacts-closed position due to such wear upon the faces of contacts 6, fill.

Where high currents are to be carried by the structure of this invention, a sutficiently large conductive path should be provided between contact arm 4 and terminal 82. However, in order to retain the necessary flexibility of flexible conductor 7, the diameter of that member should be maintained relatively small. In the modification of FIGURE 3, a second fixed contact 8 is provided at the end of the contact arm 4 nearest the pivot pin 35. In the closed-circuit position, movable contact it rests in abutment with fixed contact 81. Connecting fixed contact 81 with terminal 82 is a conductive member 84. It is apparent that conductive member 84, when contacts 8, 81 are closed, offers a current path parallel to flexible co-nductor 7.

In the FIGURE 3 embodiment utilizing two pairs of contacts, assuming the closed circuit condition, the contacts will be opened by manipulation of toggle 2 causing the switch arm 3 to pivot counter-clockwise about pivot shaft 31, which in turn causes pins 35 and 36, fixed with respect to the switch arm 3, to rise. Since there is little clearance between the aperture 45 and pin 35, the left end of the contact arm 4, as viewed in FIGURE 3, will rise first; the right side of contact arm 4, however, will not move until pin 36 reaches the top of slot 46, whereupon that end of the arm is also lifted. The result of this action is a sequential opening, first of contacts 8, 81 and then contacts 6, 61. Closing of the switch takes place in the reverse order. With pin 36 at the top of slot 46, arm 4 being biased away from actuating member 3, the contacts 6, 61 will meet first, and contacts 8, 81 will then meet in sequence. Thus, with the contacts closed, current flowing from the arm 4 to the terminal 82 will be divided, flowing through both flexible conductor 7 and fixed conductive member 84. Upon opening of the circuit in the FIGURE 3 embodiment, contacts 8, 81 will first breaker, and the entire current will be momentarily carried by conductor 7. Substantially instantaneously, however, contacts 6, 61 will be broken and the circuit interrupted. Since contacts 6, 61 remain closed after contacts 8, 81 are open, it is at contacts 6, 61 that the main arc of interruption will be drawn.

It should be apparent that the floating pivot arrangement for the contact arm 4 in accordance with the invention assures that both contacts 6 and 8 will establish a firm electrical contact with their respective fixed contacts 61 and 81 when the switch is closed.

Referring now to FIGURE 4, still another embodiment incorporating the invention is illustrated. In this embodiment, the fixed conductive member 84, as illustrated in FIGURE 3, is eliminated. In place of the terminal member 62 of FIGURE 3, a terminal member 64, in the FIGURE 4 embodiment, is extended between fixed contact 61 and fixed contact 81. In this embodiment, incorporating the basic contact arm, and utilizing, as in the FIGURE 3 embodiment, two pairs of contacts, provision is again made for drawing the arc across the heavy duty pair of contacts 6, 61 and thus avoiding arc damage to the main current contacts 8 and 81.

In the operation of the FIGURE 4 embodiment, assuming the circuit-closed position, as the switch arm 3 is pivoted counterclockwise by operation of the toggle 2, the left side of arm 4, or that side corresponding with pin 35, is first lifted, causing contacts 8, 81 to breaker. The current path is then continued from terminal 82, through flexible conductor 7, contact arm 4, and are contacts 6, 61 to conductor 63. As switch arm 3 continues to rotate and pin 36 reaches the limiting end of slot 46, the right side of contact arm 4 is lifted, and the are contacts 6, 61 are broken, interrupting the circuit. In this design, it will be apparent that a current path is provided through both pairs of contacts. The conductive member 64 may be made a more conductive path than arm 4 so as to carry the bulk of current during the circuit-closed condition. However, the arrangement thus described, providing sequential opening of contacts, saves the main contacts 8, 8. from damage due to the arc of interruption.

In view of the foregoing, it will be apparent to those skilled in the art that the instant invention provides an improved circuit interrupter structure having a contact arm resiliently mounted in such manner as to insure uniform abutment of contacts, and adaptable to modifications of special utility. The embodiment illustrated using the basic concept of the contact arm 4 and switch arm 3 permit high currents to be carried by the circuit interrupter, while sequential opening of two pairs of contacts protects against undesirable arcing. Moreover, due to the inherent relative simplicity of the structure and the flexibility of the relatively small diameter conductive braid or other flexible conductor, a high degree of reliability and compactness is obtained.

Although specific embodiments of the invention have been illustrated and described, it is apparent that many changes and modifications may be made in the construction and arrangement of the various parts without departing from the scope of the invention, and I therefore intend by the appended claims to cover all such modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric circuit interrupter comprising:

(a) a housing of insulating material,

(b) a first terminal carried by said housing,

(0) a second terminal carried by said housing and spaced from said first terminal,

(d) switch means for making and breaking an electric circuit between said first and second terminals comprising a switch shaft pivotally mounted in said housing,

(e) an elongated switch arm fixedly attached to said switch shaft, said switch arm comprising a generally U-shaped member having a pair of closely spaced planar wall portions connected by a bight portion,

(f) a first supporting pin fixedly carried by said switch arm and extending transversely between said wall portions,

(g) a second supporting pin fixedly carried by said switch arm and extending transversely between said wall portions, said second pin being spaced from said first pin and positioned closer to the outer end of said switch arm,

(h) a generally planar movable contact support be tween said wall portions of said switch arm,

(i) said contact support being pivotally mounted on said first transversely extending pin and having an elongated slot therein receiving said second pin, said slot extending in a direction generally parallel to the direction of movement of said switch arm to permit 5 limited pivotal movement of said contact support With respect to said switch arm,

(j) a compression spring compressed between said bight portion of said switch arm and an edge portion of said contact support, said compression spring being positioned between said first and second transverse pins,

(k) a movable contact member carried by said contact support adjacent the outer end thereof and adapted to engage a relatively stationary contact carried by said second terminal means,

(I) and a flexible electrical connector connecting said contact support to said first terminal means.

2. An electric circuit interrupter comprising:

(a) a casing of insulating material,

(b) a first terminal mounted in said casing,

(c) a second terminal mounted in said casing and spaced from said first terminal,

(d) a relatively stationary contact mounted in said casing and connected to said second terminal,

(6) an elongated contact arm pivotally supported in said casing,

(f) a movable contact supporting member resiliently mounted on said contact arm,

(g) a movable contact member carried by said contact supporting member and disposed and arranged to contact said relatively stationary contact in at least one predetermined position of said contact arm,

(h) a second relatively stationary contact mounted in said casing and connected to said first terminal means,

(i) a second movable contact carried by said contact supporting member and disposed and arranged to contact said second relatively stationary contact,

(j) and flexible conductor means connecting said first terminal directly to said contact supporting member, said flexible conductor being electrically in parallel with said second movable and said second stationary contacts when said contacts are in closed condition.

References Cited in the file of this patent UNITED STATES PATENTS 2,025,697 Baker Dec. 24, 1935 2,031,516 Tritle Feb. 18, 1936 2,302,394 Seaman Nov. 17, 1942 2,514,839 CasWell July 11, 1950

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