US3396255A - Switch with two contact pairs - Google Patents

Description

5 w. A. DE SMIDT 3,396,255

SWITCH WITH TWO CONTACT PAIRS Filed Dec. 16. 1966 1&9.

INVENTOR WOODROW A. DE smor ATTORNEY United States Patent 3,396,255 SWITCH WITH TWO CONTACT PAIRS Woodrow A. De Smidt, Whitefish Bay, Wis., assignor to Allen-Bradley Company, Milwaukee, Wis., 21 corporation of Wisconsin Filed Dec. 16, 1966, Ser. No. 602,394 Claims. (Cl. 200-153) ABSTRACT OF THE DISCLOSURE This disclosure relates to a switch including/a case with two terminals at opposite lower corners. Two resilient leaves extend upwardly from the terminals and turn inwardly to define parallel, vertically spaced contact portions that are biased together and that each bear two contacts to have two spaced pairs of contacts. An actuating arm is pivotally mounted in the case at its inner end and carries a bar shaped cam which extends between the leaves between the contact pairs. The cam pivots with the arm between a first position where it spreads the contact portions to open both contact pairs and a second position where it is disengaged to allow both contact pairs to close. The arm extends above the case and is mechanically operable to be pivoted toward one of said positions, and a bias spring operates between an abutment on the case and the arm to urge the arm toward the other of said positions.

Background of the invention (1) Field.This invention pertains to a mechanically operable resilient leaf switch construction useful in auxiliary switches, relays and the like which includes two pairs of contacts for enhanced reliability.

(2) Prior art.A variety of mechanically operable resilient leaf switch constructions are known. These usually involve a single pair of contacts at least one of which is carried on a resilient leaf, the resilience of the leaf serving to bias the contacts toward either a normally open or a normally closed position. A plunger or other mechanical actuator is used to overcome the resilience of the leaf and close or open the contacts as the case may be, and upon disengagement of the actuator the resilient leaf causes the contacts to assume their original positions. Such switches are quite advantageous from the standpoint of simplicity and cost, but they are not particularly reliable, especially insofar as the contact action in one direction depends only upon the resilience of the leaf. A slight loss of resilience as the result of long usage can, for example, easily prevent proper contact operation. Further, dust or dirt may relatively easily prevent proper closing of the single pair of contacts.

Summary of the invention This invention contemplates a mechanically operable resilient leaf switch construction including two resilient leaf portions presenting two spaced pairs of contacts that are normally biased toward one another by virtue of the resilience of the leaves. The contacts may be opened mechanically by virtue of a cam carried by an actuating arm. Upon disengagement of the cam, the leaves move together and the two spaced pairs of contacts in effect insure that there will be adequate contact. That is, at least one pair of contacts is virtually certain to make effective electrical contact insuring a completed circuit through the switch. It is the object of this invention to provide a switch construction of this type which is highly effective but relatively simple and inexpensive, and which is easily convertible between normally open and normally closed types of operation.

3,396,255 Patented Aug. 6, 1968 Brief description of the drawings The attached drawing, which comprises a part hereof, shows three preferred embodiments of the invention, as follows:

FIG. 1 is an exploded view in perspective of a switch constituting one embodiment of the invention,

FIG. 2 is a front view in elevation of the embodiment of FIG. 1 (the cover portion of a case for the switch being removed to show the interior parts) showing the switch in open condition.

FIG. 3 is a view similar to FIG. 2, but showing the switch in closed condition.

FIG. 4 is a view similar to FIGS. 2 and 3 but showing a second embodiment of the invention, and

FIG. 5 is a view similar to FIGS. 2-4 but showing a third embodiment of the invention.

Description of the preferred embodiments The embodiment of the invention shown in FIGS. l-3 includes an insulating case designated generally by the reference numeral 1. The case 1 is preferably of a split construction comprising a rear portion or base 2 and a front portion or cover 3, the cover 3 being omitted in FIGS. 2-5 to show the internal parts. The base 2 and cover 3 are provided with mating central bosses 4 at their bottom edges, and a pin or rivet 5 extends through the bosses 4 to hold the case portions 2 and 3 together.

A pair of U-shaped terminals 6, provided with terminal screws 7, are mounted at and extend outwardly through the bottom of the case 1 at its lower corners, the terminals 6 being provided with locating notches 8 which receive projections 9 formed in the case 1 to orient and hold the terminals 6 in place.

A pair of leaves 10, formed of strips of suitable resilient, electrically conductive material, have their lower ends fixed to respective terminals 6. The leaves 10 extend upwardly and then turn inwardly at right angles and extend across the case 1 to present and define horizontal, vertically spaced contact portions 11 which terminate at free ends on opposite sides of the case 1. The leaves 10 are shaped so that the contact portions 11 are resiliently biased toward one another. The two portions 11 each carry a left contact 12 and a right contact 13, the contacts 12, 13 being in alignment to present two horizontally spaced pairs of contacts, the members of both pairs being normally biased toward one another by virtue of the resilient bias of the portions 11. Between the contact pairs 12, 13 the portions 11 are offset apart at 14.

An inverted triangular well is formed at the upper central portion of the base 2 which receives an actuating arm 16, the arm 16 being pivotally mounted at its inner end by means of a trunnion 17 which is rot-atably received in an opening 18 in the rear wall of the well 15. Extending forwardly from the inner end of the arm 16 is a cam 19 which is formed integrally therewith and which extends between the contact portions 11 and between the contact pairs 12, 13, being received in the space provided by the offsets 14. The cam 19 pivots coaxially with the arm 16 and is provided with a trunnion 20 which is rotatably received in an opening 21 in the cover 3 to complete the pivotal mounting of the arm 16. The cam 19 is substantially bar shaped and its pivotal axis is at its midpoint.

The base 2 is further provided with an upstanding abutment 22 which seats a compression spring or bias means 23 which bears against the arm 16 to urge it to pivot in a counterclockwise direction as seen in FIGS. 2 and 3.

The spring 23 is of suflicient strength to overcome the resilience of the leaf portions 11 and normally holds the arm 16 in the counterclockwise position shown in FIG. 2 where it is against the left hand edge of the well 15. In this position, the bar cam 19 is transverse to the contact portions 11 and its ends have engaged and spread the portions 11 apart to open both contact pairs 12, 13. The arm 16 can, however, be mechanically engaged by a suitable operator, indicated as 24 in FIG. 3, to be pivoted in a clockwise direction to the position of FIG. 3 in which the spring 23 is compressed and the arm 16 is against the right hand edge of the well 15. In this position, the cam 19 is in a horizontal position where it is parallel to and in effect disengaged from the portions 11, the resilience of the portions 11 then causing both contact pairs 12, 13 to close. It will be obvious that the operator 24 may be of any suitable type depending upon the appliaction to which the switch is put. It might, for example, be the armature of a contactor or the plunger of a solenoid. Under some circumstances, the arm 16 may even be pivoted manually. pon release of the force exerted by the operator 24, the spring 23 will cause the arm 16 to move back to the position of FIG. 2, thus opening the contact pairs 12, 13.

The two pairs of contacts 12, 13 insure that there will be in effective electrical circuit through the switch even when the contact portions 11 may have lost some resilience or be slightly out of line, or where there may be dust or dirt present, it being virtually certain that at least one pair will make good electrical contact. In addition to insuring closing, however, the construction shown insures effective opening of the contact pairs 12, 13. It will be noted that as the cam 19 pivots with the arm 16 its ends will engage both contact portions 11 and cause them to be spread or flexed in opposite directions about their fixed ends, the ends where the leaves 10 turn at right angles to lead to the terminals 6. Since the fixed and free ends of the two portions 11 are op posite, they always remain substantially parallel, insuring that both contact pairs 12, 13 will be opened and will open at substantially the same time.

The flexibility of the portions 11 provides a slight wiping action which is helpful in insuring good electrical contact between the contacts 12, 13. This effect is enhanced in the embodiments shown by the vertical portions of the leaves 10 which also flex slightly during opening and closing. Although this configuration is preferred, however, the leaves 10 need not necessarily be angled as shown and the portions 11 could, for example, lead directly laterally outwardly to terminals on opposite sides of the case 1.

The embodiment of the invention shown in FIGS. 1-3 has a normally open type of operation in that the contact pairs 12, 13 are normally held apart by the action of the spring 23. The embodiment shown in FIG. 4 is substantially the same, but provides a normally closed operation. In FIG. 4, the same reference numerals have been used to designate the several elements with the exception of the actuating arm and cam. In this embodiment there is an actuating arm 25 which carries a cam 26, both of which are quite similar to the arm 16 and cam 19 except that the radial orientation of the cam 26 with respect to the arm 25 is such that when the arm 25 is in the position shown in FIG. 4, where it is normally held by the spring 23, the cam 26 is parallel to and disengaged from the portions 11 and the contact pairs 12, 13 closed. Mechanical pivoting of the arm 25 to the right or clockwise against the spring 23 will cause the cam 26 to open the contact pairs 12, 13.

The embodiment of the invention shown in FIG. is also essentially the same as that shown in FIGS. 1-3 and the same reference numerals have been used throughout to designate the several elements. In the embodiment of FIG. 5, however, there is a second upstanding abutment 27 on the base 2 on the opposite side of the arm 16, and the spring 23 is shown as operating between this second abutment 27 and the arm 16. With the spring 23 on this side of the arm 16, the switch is normally in the position of FIG. 5 to give it a normally closed type of operation. Moving the spring 23 so that it operates between the arm 16 and the abutment 22, as shown in FIGS. 2 and 3, will, however, easily convert the switch to a normally open type of operation like that shown in FIGS. 1-3.

Although three preferred embodiemnts of the invention have been shown and described, it will be obvious that various modifications might be made without departure from the invention. It is not intended that the invention be limited by the showing herein or in any other manner except insofar as limitations appear specifically in the following claims.

I claim:

1. A switch comprising: a case; a pair of terminals mounted in the case; a pair of leaves mounted in the case and connected to respective terminals and presenting parallel facing elongated contact portions resiliently biased toward one another, each contact portion having a fixed end and a free end with the free ends of the two portions being opposite, each contact portion carrying two spaced contacts which face the contacts of the other contact portion to present two spaced pair of contacts each of which is adapted to open and close, closing of either pair of contacts serving to complete an electrical circuit between the terminals regardless of whether the other contact pair is closed; an actuating arm pivotally mounted in the case and carrying a cam which extends between the contact portions between the contact pairs, the arm being pivotal between a first position in which the cam engages and holds the contact portions apart to open both pairs of contacts and a second position in which the cam is not in operative engagement with the contact portions so that both contact pairs are free to close, the arm being adapted to be mechanically engaged by an operator to be pivoted toward one of said positions; and bias means operating against the arm to urge it toward the other of said positions.

2. A switch according to claim 1 wherein the arm has an inner end at which it is pivotally connected to the case; and the cam extends laterally from the inner end of the arm and pivots coaxially therewith, the cam being bar shaped with its pivotal axis at its midpoint; and the contact portions lie in the plane of pivotal movement of the cam, the free ends of the two portions being on opposite sides of the cam, the cam being parallel to the contact portions when the arm is in said second position and transverse to the contact portions when the arm is in said first position, the opposite ends of the cam engaging respective contact portions as the arm moves toward said first position to cause them to be flexed in opposite directions about their fixed ends.

3. A switch according to claim 2 wherein the contact portions are offset apart between the contact pairs to receive the cam.

4. A switch according to claim 2 wherein the arm extends outwardly of the case; and there are two abutments on the case on opposite sides of the arm and the bias means comprises a compression spring adapted to be seated between either abutment and the arm.

5. In a switch the combination comprising:

a first electrically conductive, elongated leaf with an anchored end from which the leaf extends and which is pivotal about the anchored end, said leaf being adapted for connection in an electrical circuit;

a second electrically conductive, elongated leaf with a substantial portion of the length thereof in overlapping, facing relation to said first leaf and having an anchored end disposed at the side of the facing portions of the leaves opposite the side on which the anchored end of the first leaf is located, said second leaf being pivotal about its anchored end and being adapted for connection in an electrical circuit;

said first and second leaves being resiliently biased to urge the overlapping portions toward one another;

a set of two contacts mounted on and spaced along the length of the first leaf which face the second leaf;

a second set of two contacts mounted on and spaced along the length of the second leaf which each face a contact of the first set, to thereby establish two pair of facing contacts with the contacts of a pair movable toward and away from engagement with one another;

said contacts when in engagement providing a space between said leaves that is also between the two contacts of each set; and

a double ended operating cam disposed between the 10 References Cited UNITED STATES PATENTS 2,641,663 6/1953 Krieger 2006 X 2,903,531 9/1959 Winter ZOO-453.1 X

FOREIGN PATENTS 142,575 1/ 1931 Switzerland. 1,332,034 6/ 1963 France.

ROBERT K. SCHAEFER, Primary Examiner.

H. BURKS, Assistant Examiner.

Images