US2524411A - Electric snap switch - Google Patents

Description

F. J. TRAINOR ELECTRIC SNAP SWITCH Filed April 1, 1949 Fig I 40 iii lw lwk 9 INVENTOR. Fbstercl Tr ainor BY v AT HNEY Patented Get. 3, 1950 UNITED STATES PATENT OFFICE ELECTRIC SNAP SWITCH Foster J. Trainer, Holly Hill, Fla.

Application April 1, 1949, Serial N 0. 84,842

nism.

Another object the provision of a mechanism for translating successive reciprocal movements of a push-button in oppositely directed arcuate motion of a lever.

Another object is the combination of a resilient dished open center snap element with the lover of the preceding paragraph to cause successive actuations of the push-button to reverse the direction or convexity of the snap element.

Still another and important object is the provision of switch contacts combined with the snap element of the preceding paragraph whereby successive actuations of the push-button alternately close and open the switch contacts ab- Another object or this invention is the provision of a switch actuating mechanism which provides for a delay between the initial part of the push-button actuation and the reversal in condition of the switch contacts.

Still another object is the provision of a dished snap action element which reverses its condition of convexity with a wave motion thereby resulting in easy, quiet and delayed action.

Further objects of the invention will become apparent as the description proceeds with reference to the figures of the drawing in which:

Figure 1 is a side elevational view of the snap action element.

Figure 2 is a cross-sectional View of a complete switch utilizing the snap action element of Figure 1.

Figure 3 is an enlarged fragmentary view of certain parts of the switch actuatingmechanism.

In practicing the invention, I provide an insulatingswitch housing having a switch chamber therein with one or more fixed contacts supported on one or more walls of the housing. A movable contact or contacts is secured to a dished snap action element, the configuration of "which is reversed by a bifurcated actuation lever pivoted at one end from the side walls of the housing. In the top of the housing, an actuat- -ing shaft is slidably supported and is affixed to l the center of a down-turned U-shaped member in the switch chamber. The U-shaped member is provided with cam members pivotally supported uin each of its legs, These cam membersone or i the other engages one of two projections laterally aflixed to the bifurcated lever member depending upon the inclination of the lever member.

The depression of the actuating member causes a rotary motion of thebifurcated lever member due to engagement with the cam element in that leg of the U-shaped member toward which the lever is inclined. The movement of the lever flexes the snap element and, after appreciable movement has taken place, the fiexure in the snap element spreads through the remainder of snap element finally reversing the position of the movable contacts.

Referring now to Figure 1 of the drawing, the snap actionelement I0 is shown having a generally rectangular portion having a dished configuration around a generally centrally located aperture I l. The snap action portion terminates in a laterally elongated base portion [2 towhich, adjacent the snap action portion, are affixed movable switch arms I3. Contact elements 40 and ii are afiixecl to the ends of switch arms [3.

Referring to Figure 2, the snap element is combined with my novel actuating mechanism in a switch housing 14. The snap action element is pivotally supported along its lower edge by a groove G5 in a metal block it which is supported by the bottom Wall of the housing.

The upper portion of the snap action portion of the snap action element is supported in a bifurcation IT in an actuating lever element l8. The lever element is pivotally supported from the lateral walls of the housing by a shaft I91 positioned vertically above the snap action element lever support groove l5.

From the foregoing, itfollows that the bifurcated lever is biassed by the snap action element to one inclined position or the other with respect to a line passing through the lower snap action element support and the lever pivot. The condition of convexity of the snap action element is reversible by the application of force to the side of the lever corresponding to the convex side of the snap action element. The application of such a force causes the bifurcated lever to rotate initially causing flexure of the upper portion only of the snap action element. As the motion of the lever progresses well past center .in the opposite position, the snap action element flexure progresses until finally the stress in the snap action element itself is able to propagate the flexure to complete the reversal in convexity of the snap action element.

The progressive reversal of convexity of the snap action element is made possible by the presence of the large aperture and the .applicatiomot the reversing force to the metal along only a rather small portion of the circumference of the aperture. The consequences of such progressive reversal are a smaller activating force, a quieter action, and a strain in the metal of the snap action element which is so small that numerous flexures cause no deterioration.

To the end that each depression of an actuating knob will alter the position of the snap action element, a mechanism is provided for automatically selecting alternate directions of movement of the bifurcated lever.

The actuating mechanism is described with reference to Figures 2 and 3. This mechanism includes an actuating shaft 2i slidably supported in the top of the switch housing, on a line with the median points of the snap action element lower support groove and the bifurcated lever shaft.

The outside end of the actuating shaft is provided with a push-button ii. A compression spring 22 encircles the actuating shaft and exerts pressure between the push-button 2| and the outer surface of the switch housing to thereby return the push-button, after an actuation, to the outward or ready position. It will presently become apparent that the compression spring is an essential element in readying the snap action element actuating mechanism for successive actuations.

The end of the actuating shaft which is within the housing is coplanarly affixed to the central part of the closed end of a U-shaped element 23. The free ends of the U-shaped element are slidably supported in apertures lying in a plane normal to and passing through the median points of the snap action element supporting groove and the lever axle.

The legs of the U-shaped member are bifurcated in a plane transverse to the bifurcated lever axle for at least a distance from slightly below the lever axle to approximately the level of the lower end of the bifurcated lever.

In order that downward motion of the knob and therefore the U-shaped member will cooperate with the bifurcated lever to actuate the snap action element, cam members 24 and 25 are pivotally supported in the U-shaped member legs .26 and 2! and cooperate with the opposed bifurcated lever portion.

The outer surface of the legs 26 and 21 of the bifurcated lever member I3 is provided with outwardly directed projections 28 and 29, respectively. Spaced from the projections 28 and 29 by a distance slightly less than the extent of motion of the activating member are a second pair of outwardly directed projections 39 and 3! for a purpose presently to become apparent.

The cam members are elongated in shape having an arcuate edge extending from one end to the other, and are bounded on the side opposed thereto by a first and a second straight edge joined in an obtuse angle. The end of the first straight edge joins the arcuate edge at the pivot end. A reentrant angle having one side parallel to the longitudinal axis of the cam memher and the other side substantially normal thereto joins the second straight cam edge to the arcuate edge. There is thus provided a latch end on each cam member.

The cams are pivotally supported in the actuating U-shaped member leg bifurcations with the arcuate edge inwardly directed toward each other. Secured to the outer edge of each of the U-shaped member legs is one end of a flat spring.

The free end of the flat spring presses against the first straight cam edge to thereby urge the arcuate edge and the latch end inward toward the actuating lever.

The actuating U-shaped member, the cams and the actuating lever are so proportioned that the cam latch end is between the actuating lever outward projections on that side of the actuating lever corresponding to the direction of convexity of the snap action element.

The operation of the device through two successive manipulations of the push-button is as follows: The initial state is assumed to be as shown in Figure 2. The cam in the right hand U-shaped member is in a position such that the path of the cam latch end engages the lower outward projection on the actuating lever. As the U-shaped member is progressively depressed, the cam member 25 is rotated thereby increasing the lateral distance between the latch end of the U-shaped member leg 21. It follows that the actuating lever I8 is rotated clockwise thereby flexing in a clockwise direction the upper portion of the snap element. The flexure of the upper portion of the snap element is progressively increased with progressive depression of the push-button until a point is reached at which the snap action element upper portion has been sumciently reversed in direction to, by itself, propagate the flexure. Therefore, at this point, the snap element consummates the reversal in direction of convexity.

At this point, the actuatin lever is likewise reversed in condition of inclination and, it is assumed that the push-button is still depressed and the left leg of the activating lever has depressed the left cam into the position shown by the right cam in Figure 3.

The push-button is now released and retracts due to the action of spring 22. When the actuating mechanism is nearly in the position of full retraction, the left cam 26 latch portion clears the lever left leg projection 28 and is urged inwardly by spring 32 to a position so as to engage the projection 28 on the next push-button projection. Also when the actuating mechanism is in this position, the inwardly directed right cam 25 strikes the upper projection 3| on the actuating lever right leg and is rotated counter-clockwise sufficiently to insure control by engagement of spring 33 against the first straight edge.

The mechanism is thus substantially prepared for reversal by a succeeding actuation of pushbutton 2|.

The next depression of the push-button causes the actuating mechanism to take the position shown in Figure 3. Upon release of the push-button, cam 24 strikes actuatinglever left leg projection 3E! and thus rotates into normal position in which it will clear the actuating lever projection 28 on the next push-button actuation.

Thus far, I haveshown a mechanism for automatically causing reversals in convexity of a snap action element by successive actuations of a single push-button.

In order that a delay in time will be obtained between initial actuation of the push-button and the actuation of electrical contacts, the moving electrical contacts 40 and M are connected by arms 42 and 43, respectively, to the lower portion of the snap action element. By this arrangement, the motion of the contacts is delayed from the time of initial actuation of the pushbutton and, in addition, is very abrupt in action.

The electrical assembly is completed by the provision of stationary contacts 45 and 46 affixed to connectors 41 and 4B. The connectors terminate at their free end in terminals 49 and 50 respectively. The moving contacts are provided with terminal 5|.

The switch assembly has been described as a single pole double-throw type, but it is understood that this has been done for the purpose of description only and that any selected order of switch contacts may be used in a manner apparent to those skilled in the art.

Therefore, I have described a mechanism for translating successive reciprocation motion of a shaft into oppositely directed rocking motion of a pivoted member, and also, the combination of the pivoted member with a snap action element whereby successive reciprocations of the shaft cause reversals in condition of the snap action device, and in addition to the foregoing, one or more electrical contacts, cooperati vely engaged with the snap action device whereby actuation of the reciprocating shaft causes a delayed, but abrupt, actuation of one or more electrical switches.

I have, therefore, described certain specific embodiments of my invention, but it is likely that other modifications are possible without the exercise of more than the skill of those versed in the art, so that it is understood that the foregoing is descriptive and not limiting, and that the invention is limited only by the claims as interpreted in view of the prior art.

What is claimed is:

1. In a device of the class described, a dished open center resilient snap action element, means for pivotally supporting the lower edge thereof, a pivoted lever having a depending bifurcation, the legs of said lever defining the bifurcation straddling the upper portion of the snap action element, an outwardly extending projection on the lower ends of said lever legs; an inverted U-shaped actuating member slidably supported and having legs, a cam member having a latch portion pivotally supported on each of said U- shaped member legs, and spring means causing said cam member latch portions to extend inwardly toward the bifurcated lever legs and so proportioned that one of said cams engages the bifurcated lever legs outward projection on the side corresponding to the direction of convexity of said snap action element, whereby downward sliding of said U-shaped actuating member causes fiexure and reversal in the direction of convexity of the snap action element.

2. In an electric switch having a single pushbutton, a snap action element in the form of a dished open center resilient sheet having at least a lower edge and an upper portion, a dielectric case having a switch chamber, an upperly open groove associated with the bottom wall of the switch chamber, said snap action element lower edge being pivotally supported on an axle parallel with and vertically aligned with said groove, said snap action element upper portion being engaged by the walls of the lever bifurcation; an actuating shaft slidably supported in a top wall of the switch chamber and being attached to said pushbutton at the free end and being afiixed to an inverted U-shaped member in the switch chamher, the lower ends of the U-shaped member being slidably supported in a lower wall of the switch housing, and means linking the leg of the U-shaped member to the bifurcated lever on the side corresponding to the direction of convexity of the snap action element, where successive actuations of the push-button cause said lever to swing in a limited arc in opposite directions to thereby successively reverse the direction of convexit of the snap action element.

3. In a snap action switch, a housing having lateral side walls, end walls and top and bottom walls, a snap action element having a dished configuration and an open center, a U-shaped groove normal to the lateral side walls and supported along a median line on the inside of the housing bottom wall, said snap action element having a lower straight edge supported by the walls of said U-shaped groove, a depending lever pivoted from the lateral side walls, and having a pair of depending legs separated by a bifurcation, said legs lying in a plane normal to the axis of rotation of said lever, said lever legs straddling with a snug fit the upper portion of the snap action element, an outwardly directed extension on the lower end of each of said lever legs; an actuating rod slidably supported in the housing top Wall and being affixed to the median point of an inverted U-shaped member, said inverted U- shaped member having a pair of depending legs slidably supported in the housing bottom wall, and being orientated in the plane of the lever legs and straddling the same, a pair of elongated generally triangularly shaped cams each having a convex edge extending between the ends of the elongation thereof and being bounded on the remaining perimeter thereof by a pair of straight edges joined by an obtuse angle and a reentrant. angle, one free end of a first of said straight edges joining the convex edge in a point, and the second straight edge joining the convex edge in said reentrant angle to thereby define a latch dog; one each of said cams being pivotally supported at the end, defined by the junction of a straight edge and the convex edge, by one of the U-shaped member depending legs and being orientated whereby the convex edge is directed inwardly, a fiat spring member secured to the other edge of each leg of the U-shaped member and pressing inward on the cam first straight edge thereby urging the cam latch dog into an inwardly inclined position, whereby a downward motion of the actuating rod is translated by engagement of the cam with the projection on the lever leg on the convex side of the snap action element into a rotational movement to thereby reverse the direction of convexity of the snap action element, at least one movable electrical contact element aflixed to a lower portion of the snap action element, at least one fixed element supported by the said switch housing and posi tioned to engage the movable contact when. said switch is in on-condition, whereby successive actuations of said actuating rod alternate the opened or closed condition of the switch contacts.

FOSTER J. TRAINOR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 829,162 Klein Aug. 21, 1906 1,538.882 Bates May 26, 1925 1,961,722 Walker June 5, 1934 1,988.345 Vaughn Jan. 15, 1935 2,266,537 Elmer Dec. 16, 1941 2,395,698 Tiifany Feb. 26, 1946

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