US2892908A - Electric switch - Google Patents

Description

H. N. coPPocK .ELECTRIC SWITCH June 30, 1959 3 Sheets-Sheell l med Dec. 24. i956 INVENTOR. Harold JV. Coffee/r BY Hfs ATTORNEY H. N. COPPOCK ELECTRIC SWITCH June 30, 1959 3 Sheets-Sheet 2 Filed Dec. 24, 1956 Harold JY.' BY

Hfs ATTORNEY June 30, 14959 H. N. coPPocK 2,892,908

ELECTRIC swITcH Filed M0924l 1956 3 Sheets-Shea?I I5 /7//5 rroe/VEY v atent iiice Patented June 30, 1959 ELECTRIC SWITCH Harold N. Coppock, Marion, Ind., assignor to General Motors Corporation, Detroit, Mich., a; corporation of 'Delaware Application December 24, 1956, Serial No. 630,191

11 Claims. (Cl. 200-67) This invention relates to snap action devices and is particularly 'i concerned with snap switches that maintain high contact pressure until the instant of break.

This invention is a continuation-in-part of my application, Serial No. 581,938, led May l, 1956, now abandoned.

It is, therefore, the main object of the invention to provide a switchl which is so constructed that contact pressure is maintained until the instant of break whereby arcing at the contacts is substantially eliminated.

In carrying out the above object, it is a further object to provide a snap acting device comprising a support having opposed bearing surfaces upon which an actuating arm and a contact arm each having a square-cut end are adapted to be seated, the actuating arm preferably being of greater thickness and less length than the contact arm. Spring means are provided to draw the square-cut ends of'saidrarms into engagement with the bearing surfaces whereby as the actuating arm is moved, the force cornponents are so directed through the spring that the contactarm does not move until after the actuating arm is being snapped. to another position whereby the spring causes the Contact arm to follow.

A still further object of the invention is to provide a snapA action switch of the toggle type including two opposed arms having square-cut ends which rock upon bearing support surfaces, the arms being connected by a tension spring whereby one arm must rock off one edge of its square-cut surface onto lthe square-cut surface and then onto the other edge thereof before the components of forceof the spring begin to cause the other arm to move whereby the other arm is moved with a snap action and without appreciable reduction in contact pressure until the instant of'break.

Further objects and advantages of the present invention will be apparent from the following description, referencebeing had to the accompanying drawings wherein a preferredembodiment of the present invention is clearly shown.

In the drawings:

Figure 1 is a cross-sectional View of a switch of the character described in the oft position.

Figure 2 is a view similar to Figure l wherein the actuating member has been moved to its dead center position.

Figure 3 is a view similar -to Figure l wherein the switch ,has snapped to the on position.

yFigure 4 is a View taken on line 4--4 `of Figure `2.

Figure 5 is a View taken on line 5 5 of Figure 4.

Figures 6, 7 and 8 are greatly enlarged views of the position of the ends of the toggle arms as shown in Figures 1, 2 and 3respectively.

Figures 9, 10 and 11 are greatly enlarged views of the position of the ends of the `toggle arms as shown in Figures l, 2 and 3, respectively, wherein modified bearing surfaces are used.

Snap action devices and particularly snap switches, vary considerably in their constructional details and,

therefore, vary widely with respect to the operation thereof. In most snap action devices, and particularly in snap action switches, the switch is moved toward dead center position, the component of force created by the spring means, if the switch is of the toggle type, lessens appreciably until a point is approached at whichthis component is substantially zero with respect to contact closing pressure. When this occurs, vibration of the surrounding environment may cause the contacts to chatter and arc which is highly undesirable.

The present switch is a toggle type switch wherein, due to the construction thereof, contact pressure is main? tained until the contact arm is ready to snap to another position. This is accomplished by eliminating the usual knife edges used in connection with the toggle arms of snap switches and replacing them with squarecut ends on the toggle members which rock upon actuation thereof. The square-cut ends are made by the usual punch press operation with any wire or sharp edges removed as by tumbling.

Referring specifically to Figure 1, a switch 20 is shown which includes a metal housing or casing 22 that has associated therewith a bifurcated support member 24 formed in two parts, namely, integral projections 25 formed on the housing and a mating part 27 which is clamped in place when cover. 29, preferably of insulating material, is assembled with `the housing. Intermediate the two sides of the support 24 is a pair of opposed flat bearing surfaces 26 and 28. These surfaces may be parallel to one another as shown in Figures 1 through 8 or they may be formed so that one surface.26` is out of parallelism with the surface. 28 as noted in Figures 9, 10 and 11. This latter design is .used to prevent any possibility of hang-up at dead center positionand may be useful when rather low actuating pressures are used on the actuator. In most instances, the parallel surfaces function quitewell. These surfaces are of substantial width and extend across the entire extent of the bifurcated support 24. Bearing on the surfaces 26andz28 are two toggle arms 30 and 32, respectively. The arm 30 may be termed the contact arm and includes a contact 34 at its outer end. The arm 32 may be termed the actuating arm and preferably includes an `actuator-36 formed integral therewith and may have an insulating handle 37 thereon. The actuator36 is bent from the arm 32 and extends through an aperture 38 in the-cover 29 so .thaty it is easily manipulated. Within the casing 22 is a stop 40 for the contact 34 which stop is in an opposed` position to a contact 42 carried by the insulated cover 29.y In switch operation, contact 42 forms one. side of the circuit while the casing 22 forms the other side thereof. Itis understood that the stop 40 may be a Contact, if it is desired, to provide a double throw switch and this is fully within the scope of the invention. Stops 41 and 43 are provided for the arm 32 and merely comprise portions of the housing 22 and cover 29.`

The contact member 30 and the actuating member 32 are -held together by means of a toggle spring 44.' Each member is bifurcated so as to provide space between the legs thereof for the spring. Spring 44 is in tension and holdsv the ends of the two members 30 and 32 against the surfaces 26 and 28.respectively- It will be noted that the ends of the members 30` and 32 which bear on the surfaces 26 and 2S'are square-cut and that thethickness of the members 30v and 32 .differ and in each case are less than the width' of the surfaces 26 and 28.k In fact, the member 32 is shorter than the member 30 and is thicker than the member 30.

These dimensions and conditions are of considerable importance tothe success of this device since, as it will be noted in Figures 1 and 6, with theswitch in-anoif rstien, themembsr 32 is. angled upwardly. more than the member 30 due to its shorter length and bears against the surface 28 along one edge of its square-cut end. In a like manner, the member 30 bears` against its surface 26 along one edge of its square-cut end. When the device is to be actuated, as pressure is applied to rotate the actuator 36 in a clockwise direction, the conditions shown in vFigures 2 and 7 prevail, at which time the member 32 rocks upon its square-cut end on the surface 28 while the member 30 is still bearing along the one edge of its square-cut end on the surface 26 due to the angle of the spring 44. This creates a component of force which tends to maintain the contact 34 in an upward position. As soon as the actuator 36 passes the position shown in Figures 2 and 7 and begins to rock on the other edge of its square-cut surface, the angle of the spring changes to reverse the force component thereof to cause the arm 30 to be drawn downwardly whereupon it rocks against the square-cut end onto the other edge thereof with a snap movement to take the position shown in Figures 3 and S. Of course, reverse operations are accomplished by reversal of the stated procedure. In each case, however, there is a definite component of force holding the contact 34 against the stop 34 or the contact 42 until such time that the actuator arm 32 passes its dead center position whereupon the force components change direction and snap the contact arm. In this manner, the contacts are always held in engagement with one another under definite pressure until the instant of snap action as differentiated from conventional toggle devices including knife edges wherein the components gradually reduce until a zero component of force is present just prior to the snap action of the switch whereby chattering and arcing at the contacts is permitted.

The difference in thickness and length of the members 30 and 32 is controlled to a large extent by the contact travel desired and the force required on the actuating arm 32. For this reason, the arms, while shown as being of different thickness and length, may vary in these dimensions according to the results desired although the design as set forth in the drawings is generally preferred. In all cases, the square-cut ends on the toggle members are the important factor that must be maintained in order to obtain good contact pressure up to the point of break.

It is to be understood that the casing 22 may be made of Bakelite, etc., if desired, and that in place of a single contact 42, two contacts may be used side by side which are bridged by the `contact 34 as is well known. In fact, any conventional assembly may be used in place of the disclosed structure, the invention residing in the snap action device which maintains the high contact pressure under operating conditions.

The present switch is highly useful for carrying relatively high loads due to its steady contact pressure until instant of break. It is inexpensive to fabricate and the only critical portion of the switch is directed to the square-cut ends of contact and lactuating members. These may be formed by standard punch press procedures wherein the two edge surfaces are provided upon which the members may rock. In this connection, greater precision is obtained and better Contact pressure may be realized if the ends are ground although in most instances, this expedient is unnecessary to provide a ihighly satisfactory switch.

While the embodiments of the present invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

l. A snap action device, comprising in combination, a support having bearing surfaces at opposite sides thereof and lying in the same horizontal plane, a pair of elongated arms of dilerent thicknesses and each having a square-cut end adapted to seat on one of said surfaces, spring means acting between said arms for causing said square-cut ends to be drawn into edgewise engagement with said bearing surfaces, stop means on both sides of each of said arms adjacent the ends thereof that are remote from the bearing surfaces for limiting the movement of each of said arms, and means for moving the thicker of said arms from its position against one Of said stop means toward the other of said stop means for causing the spring means to pass its dead center position for moving the other of said arms with a snap movement.

2. A snap action device, comprising in combination, a support having bearing surfaces at opposite sides thereof and lying in the same horizontal lplane, a pair of elongated arms of different thicknesses and each having a square-cut end which is adapted to seat pivotally on one of said surfaces, a tension spring acting between said arms for pulling the arms toward one another and thereby causing said square-cut ends to be drawn into edgewise engagement with said bearing surfaces, stop means on both sides of each of said arms adjacent the ends thereof that are remote from the bearing surfaces for limiting the pivotal movement of each of said arms therebetween, and an actuator for moving the thicker of said arms from its position against one of said stop means towards the other of said stop means whereby the tension spring is moved past its dead center position for causing the other of said arms to move with a snap movement in the same direction.

3. A snap action device, comprising in combination, an abutment including spaced abutment surfaces at opposite sides thereof and lying in the same horizontal plane, a pair of elongated arms of different thicknesses each having a square-cut end which is adapted to seat and pivot on one of said surfaces, spring means anchored to said arms and acting therebetween to Aresiliently seat the square-cut ends thereof into edgewise engagement with said spaced abutment surfaces, stop means for each of said arms disposed adjacent the free ends thereof whereby the arms are normally held out of alignment with one another against one pair of stop means and wherein only one edge of each of the arms square-cut ends seats on its respective abutment surface, means for moving one of said arms so as to increase the tension of said spring means for causing ultimately a snap movement of the other arm whereupon the opposite edges only seat on their respective abutments.

4. A snap action device, comprising in combination, an abutment including spaced abutment surfaces at opposite sides thereof and lying in the same horizontal plane, a pair of arms of different thicknesses each having a square-cut end which is adapted to seat and in edgewise engagement pivot on one of said surfaces, a spring for resiliently holding the arms out of alignment and in edgewise `engagement with said abutment surfaces, means for moving one of said arms in one direction for rocking the arm on its edge against said surface whereby the spring rocks the other arm only after the first mentioned arm passes dead center position of the sp-ring means.

5. A snap `action device, comprising in combination, an abutment including spaced abutment surfaces at opposite sides thereof and lying in the same horizontal plane, a pair of arms of different thicknesses each having a square-cut end which is adapted to seat and pivot on one of said surfaces, one of said arms being thicker and shorter than the other of said arms, a spring for resilinetly holding the arms out of alignment and in edgewise engagement with said abutment surfaces, means for moving one of the arms in one direction, said arms, spring and stop means being arranged so that as the arm being moved reaches its dead center position, the spring will continue to exert a force component on the other arm resisting movement thereof in said one direction and then, after the arm being actuated passes dead center position, the spring will exert a force component on the other arm for moving the arm in said one direction with a snap movement.

6. The device as claimed in claim 5 wherein both arms are provided with stops adjacent their free ends to limit the movement of said arms in both directions.

7. The device as claimed in claim 5 wherein the long arm includes a contact and at least one of the stops for the long arm is a lixed contact whereby a snap action switch is provided.

8. A snap action switch, comprising in combination, a support having abutment surfaces at opposite sides thereof and lying in the same horizontal plane, an actuating arm and a contact arm each having a square-cut end adapted to seat edgewise on one of said surfaces, the actuating arm being of greater thickness and less lentgh than the contact arm, a contact carried adjacent the free end of the contact arm, spring means acting between the contact arm and the actuating arm for causing the edge of said square-cut ends to be drawn against said opposed abutment surfaces, stop means on both sides of said arms adjacent the ends thereof that are remote from the abutment surfaces for limiting the movement of said arms wherein one of said stop means is a contact engageable with the contact on the contact arm in one position thereof and means for moving the actuating arm from its position against one of said stop means toward the other of said stop means for causing the spring means to pass its dead center position with respect to the contact arm for moving the contact arm with a snap movement.

9. In a snap action switch, the combination comprising, a pair of elongated toggle members wherein one of said members is relatively shorter and thicker than the other of said members, each of said members including a square-cut end adapted to bear upon opposite at sides of an interposed abutment and lying in the same horizontal plane, spring means attached to said toggle members intermediate the ends thereof for drawing the toggle members toward one another and thereby urging the square-cut ends against the abutment, stop means spaced from one another and positioned adjacent the free end of said shorter toggle member whereby the toggle member may pivot on its abutment and between said stop means, a contact carried adjacent the free end of the longer toggle member, a stationary contact arranged to act as a stop means for said longer toggle member and engageable with said contact on the said toggle member, said toggle members being arranged so that the shorter toggle member, when actuated, reaches dead center position with the spring in such a position that it continues to exert a force component on the contact toggle member resisting movement thereof and holding said contact on the contact toggle member in engagement with the stationary contact and then after the actuated toggle member passes dead center position, the spring will change its force component on the contact arm for moving the contact arm away from the stationary contact member with a snap movement, said action in the opposite direction of movement of the actuated toggle member being in reverse of the action described.

10. The snap device described and claimed in claim 8 when the opposed abutment surfaces are at and are parallel to one another.

11. The snap device described and claimed in claim 8 wherein the opposed abutment surfaces are at and are out of parallelism with one another.

References Cited in the file of this patent UNITED STATES PATENTS

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