US2428172A - Mechanism for precision switches - Google Patents

Description

Sept. 30, 1947. MlLLER 2,428,172

MECHANISM FOR PRECISION SWITCHES Filed March 16, 1945 IL .5: I

HQ EDWIN AUGUST MILLER W Patented Sept. 30, 1947 UNITED srAres PATENT OFFICE Claims. 1

This invention relates to mechanism for precision switches, including switches adapted for alternate electric circuits.

The objects of the invention are to provide a snap action switch which maintains a constant maximum contact pressure up to the breaking point; to provide a switch having an actuating means including a flat spring material to which resilient properties are imparted while a portion of the material is held in a predetermined manner; and to provide a switch the mechanism of which is compact, with the least required exertive pressure of operation, and adapted for a reduced arc of oscillation.

Referring to the accompanying drawing, the

' Figure 1 is an erect elevation of the device, illustrating its insulation casing in cross-section and its mechanism in a maintained at-rest position; Figure 2 is a similar elevation but illustrating its mechanism in an operated position; Figure 3 is a top surface view of the oscillating member; Figure 4 is a perspective view of the link member; Figure 5- is a perspective view of the leaf spring member; and the Figures 6 and 7 are diagrammatic layouts of two mechanical positions of the oscillating member and associated parts.

With more particular reference to the accompanying drawing, there is illustrated one form only of the invention with regard to the novel mechanism and manner by which the improvement herein set forth is achieved. Other forms within the scope of the invention may be obvious.

The casing I, of insulation material, illustrated I in cross-section, accessibly provides wire connection terminals 2, 3 and 4 adapted for electric wiring (not illustrated) for the establishment of separate alternate circuits within which the switch may be inserted. The inner extremities of terminals 2 and 3 provide the spacedly aligned fixed contacts 5 and 6 rigid with said casing I.

v The sheet-metal oscillating body member I, one

end of which is anchored, as at 8, within the casing I where it is provided with a permanent connection with the inner end of the terminal 4, as illustrated by the Figures 1 and 2, carries at its opposite end the upper and lower superposed contact surfaces 9 and I0, respectively, adapted for alternate engagements with the fixed contacts 5 and 6 in maintained at-rest and operated positions of the oscillating body member I. The tongue II is illustrated-as integral with the body member 1 and pendulously formed by being cut on three sides from within the central surfacelength thereof, the extremity of the tongue II being shortened, as at IIB, leaving unoccupied a portion of the tongue operating space 1A. The

tongue I however, is extended by means of the link I2 of which one end edge is turned downwardly, as at I3, and at the opposite end edge is provided with the extended lugs I3A, the

turned portion I3 being provided at its side edges with open marginal recesses I4 into which fit the tree lower end is movably held within the slot I6 of the casing I. Said leaf spring I5 is provided at its side edges with the open recess II within which fit the extended lugs I3A of the link I2 as a means of hinged assembly. The tension of the leaf spring I5 is exerted outwardly against the link I2 in one direction only, the link I2 thus being held at-a slight angle with the inclined edge of the tongue II and thus maintained by means of the coil spring I8, having a support rigid with the casing I. The hinged assemblies make possible an increased sensitivity of operating pressure. a

As illustrated by the Figure 1, the oscillating body member I and connected parts of the precision switch mechanism are held at-rest in an over-centered position by means of said coil springs I8. In the Figure 2, the mechanized parts are illustrated as having been operated by means of manual pressure by the thumb I9 placed upon the push element 20 whereby the link I2, together with the tongue II at the point'of their hinged connection, is depressed against the tension of the coil spring I8, thereby operating the tongue II from its over-centered position relative to the oscillating body member 'I to an under-centered position.

Due to the over-all length of the combined tongue II, link I2 and connected leaf spring I5, within their operating open space IA, being slightly greater than the entire opening IA, the tongue II, depressed by pressure upon the link I2 hinged therewith is forced to a relatively flexed condition with regard to the oscillating body member I. In such forced movement from the over-centered position, through a center to an under-centered position of the tongue II and link I! at their point of hinged connection, the body member I is sufiiciently distorted so that the transition is one of sudden snap action wherein the free end of the oscillating body member I, carrying the superposed contacts 9 and I0, engages its contact 9 with the fixed contact 5, rigid with the casing I, which contact engagement is maintained against the tension of the coil spring I8 as long as manual pressure remains upon the push element 20, as illustrated by the Figures 2and 7. With the release of such mam ual pressure, the coil spring I8 acts to reverse the operation of the mechanical parts with the same sudden snap-action as when manually op erated. Insuch reversal of action however the tongue II at the hinged connection of the link I2 passes back through center to its her lly maintained over-centered position, agai turning the engagement of the COI'ltflCtjlUWlIiljl the fixed contact Ii rigid with the casirigfI/ajs illustrated by the Figures 1 and 6, the engagement being augmented by means of the coil spring i8.

While manual pressure is herein illustrated as means by which the precision switch is operated to one of itsextreme positions, it is to be understood that such'movement of operation is adapted to be accomplished by any other means, such as when the invention is employed as a part of an automatic means adapted for precision con' trol in mass production of an article, in which case the switch may be mechanically operated as a part of such means.

In the Figures 6 and '7, it will be noted that the full line I designates the body of the oscillating member, and the dotted line i i represents the tongue member. In the Figure 6 the tongue ii, at its end connected with the link 12, is shown over-centered with relation to the body of, the oscillating member 1 while, in the Figure '7 the tongue I! at said end is shown under-centered with relation to said body i, such positions of the tongue H determine engagements of the contacts 9 and I carried by the body member 1 relative to the fixed contacts and 5.

The novel introduction herein of the hinged link 12 as an extension of the tongue H, makes it possible to build said switch mechanism within a short and more compact casing; for a length of a tongue equal to the combined short length of the tongue H and link l2 would tend to add stifiness and thus increase the required exertive pressure of operation. The hinged assembly, as employed by said mechanism, allows a. greater difierential movement as between the push element and the travel of the oscillating member 7 between the fixed contacts 5 and 6.

I claim:

l. A snap-acting control mechanism for a precision switch comprising an oscillating body member having one end fixed to a supporting base and carrying at the free end contact surfaces for alternate engagements with relatively fixed contacts rigid with said base, said body member having a central elongated opening therethrough; a tongue secured at one end to said body member within said opening; a leaf spring supported'by said base within said opening adjacent the free end of said tongue and exerting its tension outwardly along the plane of said opening; a link member interposed between said spring .and said tongue; a hinged connection between said leaf spring and said link and between the link and the free extremity of said tongue, the connected tongue, link and spring requiring a length of space greater than that of said opening, the said tongue is normally flexed to an over-centering position with respect to said body member thus distorted and engaging one of its contact surfaces with one of the fixed contacts; operating means to move said link, and

' hence the free end of said tongue with a snapaction from said over-centering position, through a-center and to an under-centering position to release said contact engagement and to engage the other contact surface with the other of said fixed contacts; and means for effecting the return movement of the oscillating member.

' and. A snap-acting control mechanism for a precision switch comprising an oscillating body member having one end fixed to a supporting base-and carrying at the free end contact surfacessfor, alternate engagements with relatively fixed :contactsrigid with said base, said body member having. a central elongated opening therethrough; a tongue secured at one end to said body member within said opening; a leaf spring supported by said base within said opening remote from said contact surfaces and exerting its tension outwardly along the plane of said opening; a link member within said opening and having hinged connections with the free end of said tongue and with said leaf spring, the connected tongue, link and spring requiring a length of space greater than that of said opening, the said tongue is normally flexed to an over-centering position with respect to said body .member thus distorted and engaging one of its contact surfaces with one of the fixed contacts; manual means for operating said link, and hence said connected tongue with a snap-acting movement from said over-centering position, through a center and to an under-centering position to release said contact engagement and engage the other contact surface with the other of said fixed contacts; and separate spring means to effect the return movement of the oscillating member.

3. An oscillating member for a snap-acting control of a precision switch, said member comprising a sheet-metal body of which one end is secured to a base and the opposite end is provided with contact surfaces, said body having an elongated opening therethrough; a tongue within a portion of said opening and secured at one end of said body; a spring supported by said base within said opening remote from said contact surfaces; a link member interposed between the free end of said tongue and said spring; and hinged connections of said tongue, link and spring in such manner that their overall length is greater than that of said opening.

4. An oscillating member for a snap-acting control of a precision switch, said member comprising a sheet-metal body of which one end is secured to a base and the opposite end is provided with contact surfaces, said body having an elongated opening therethrough; a tongue within a portion of said opening and secured at one end of said body; a leaf spring supported by said base within said opening remote from said contact surfaces and exerting a tension in one direction; a link member interposed between the free end of said tongue and said spring; and a hinged connectionof said tongue, link and spring in such manner that their overall length is greater than that of said opening.

5. An oscillating member for a snap-actingcontrol mechanism for a precision switch, said member comprising a sheet-metal body of which secured at one end to said body member; a spring supported by said base remote from said contact surfaces;a link interposed between said tongue and said spring; and a hinged connection of said link with said spring and the free end of said tongue, the overall length of the connected tongue, link and spring being greater than the space between the place of securement of said tongue to said body member and the supporting base of said spring.

EDWIN AUGUST MILLER.

REFERENCES CITED UNITED STATES PATENTS Name Date Wilms Oct. 28, 1941 Number

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