US2977436A - Snap action switch - Google Patents

Description

March 28, 1961 A. w. HAYDON 2,977,436

SNAP ACTION SWITCH 2 Sheets-Sheet 1 Filed March 26, 1958 FIG. I

F m I.

INVENTOR ARTHUR W. HAYDON BY 7 44M, 7770i", 5mm

ATTOR Y March 28, 1961 A. w. HAYDON SNAP ACTION SWITCH 2. Sheets-Sheet 2 Filed March 26, 1958 INVENTOR ARTHUR W. HAYDON M, fu e 1, @w, 162W 47 ATTORN S United States PatentO SNAP ACTION SWITCH Arthur W. Haydon, 83 Point Lookout, Milford, Conn.

Filed Mar. 26, 1958, Ser. No. 724,036

Claims. (Cl. 200--67) This invention relates to snap action electrical switches and especially to a snap action switch having a switch blade adapted to be actuated by the sudden release of energy from a resilient actuator.

In conventional snap action switches, the snapping motion of the spring blade between the switch contacts is often effected by the inversion of some resilient linkage or curved portion of the blade through the plane of the blade. ercised in the manufacture of such switches, in order to produce proper snapping motion at desired actuating pressures. Such precise manufacture adds materially to the cost of the switch, but is generally considered to be unavoidable in switches of conventional design.

One of the primary objects of this invention, therefore, is to provide a simplified and inexpensive switch which is characterized by improved snapping action and in which the snapping of the switch is accurately responsive to actuating forces or motions.

In one of its preferred forms, the new switch comprises a flat spring blade having a substantially coplanar snapping member, which may be integrally formed with the remainder of the blade or can be assembled therewith subsequent to forming. In either case, the cost of manufacture is considerably less than in conventional designs since my spring blade may be easily and accurately stamped in finished planar configuration from fiat stock, without regard to the exacting precision required in the formation of curved surfaces or assembly of linkages. 1

In accordance with one aspect of the invention, the

i switch includes improved actuating means which provide a sudden make-and-break snapping action between the contacts when the switch is actuated. This is accomplished by accumulating a supply of spring energy in the actuator until the snapping pressure of the blade is reached, and then virtually instantaneously releasing the stored spring energy to carry the blade decisively through its snapping motion. The improved actuator means, when used as an intermediate between the switch blade and exterior actuating means, renders the switch well suited for use with very slowly rotating cams, for example, which otherwise tend to be sluggish in snapping the blade, when acting thereon in the conventional manner.

One of the specific advantageous features of the invention resides in the provision of a simplified snapacting switch having a resilient snapping element and resilient actuating means and where, as the snapping element approaches a snapping condition, there is a sudden collapse or loss of resisting forces, which is not accompanied by an equivalent loss of actuating forces stored in the resilient actuating means. The arrangement is such that effective and decisive snapping of the switch is assured, even though the external actuating Extreme precision must generally be ex-- moving nature.

The foregoing and other novel features of this invention are more clearly described in the following description, taken in conjunction with the accompanying drawings, wherein:

Fig. 1 is anelevational view, partly broken away, of one embodiment of the switch with the parts thereof in normal positions;

Fig. 2 is an elevational view of the switch of Fig. 1; with the parts thereof in actuated positions;

Fig. 3 is a sectional view taken along line 3-3 of Fig. 1; a I

Fig. 4 is an elevational view of a second embodiment of the new switch with the parts thereof in normal positions;

Fig. 5 is an elevational view of the embodiment of Fig. 4, with the parts thereof in actuated positions; and

Fig. 6 is a fragmentary perspective view of the actuator and blade incorporated in the switch of Fig. 4.

Referring first to Figs. 1, 2 and 3, the switch includes a base 10 of material such as Bakelite. Three terminal brackets 11, 12 and 13, secured to and extending through the base 10, are affixed at their lower ends to corresponding L-shaped terminal receivers 14, 15 and 16, mounted in the base. Screw terminals 17, 13 and 19 are in threaded engagement with the terminal receivers 14, 15 and 16 respectively, thereby providing means for electrically connecting lead wires (not shown) to each of the separate terminal brackets 11, 12 and 13.

A lower switch contact 20 is attached to the upper portion of the terminal bracket 12, which extends a short distance along the upper surface of the base 10. The upper portion of the terminal bracket 13 projects above the base 10 and is bent over the upper portion of the terminal bracket 12. Attached to the underside of this bent-over portion, directly above the lower switch contact 20, is an upper switch contact 21. The upper portion of the terminal bracket 11 'also extends above the base 10 and is bent over above the base in the direction of the other two terminal brackets.

Secured by rivets 22 and 22 to the bent-over section of terminal bracket 11 are an actuator 23 and a spring blade 24. The actuator is stamped from resilient flat metallic stock and comprises a lever arm 26 and an integral connecting member 27. The free endof the lever arm 26 is bent slightly downwardly to form an actuator engaging surface 26a, which may readily serve as a cam follower, for example. Advantageously, the outer end portion of the lever arm 26 has considerable resilience. This resilience may be confined to the outer end portion of the arm by providing upwardly bent flanges 26b along inner portions of the arm, as indicated in Figs. 1 and 2. Also for improved resilience the outer end portion of the arm may be of substantially lesser lateral dimension than the remainder of the arm, for example as clearly shown in Fig. 6. The connecting member 27 is a substantially centrally located rectangular tonguelike portion of the lever arm 26, which is directed downwardly out of the plane of the flat stock from which the actuator is stamped. i

In the illustrated form of the invention, the spring blade 24 is formed of fiat, resilient metallic stock with a central cut-out portion 28 bounded by integral, longitudinal tension members 29 and 29' (Fig. 3). Extending longitudinally into the cut-out portion 28, toward the ten minal bracket 11, is an integral compression member 30 (rigidized by groove or depression 30 if desired) which has a tab 31 projecting from its outer extremity. In the assembled switch, the tab 31 is inserted into a corresponding aperture in the lower end of the actuator connecting member 27. The geometry of the parts is such that the connecting member 27 presses against the compression member to set up compressive stresses therein, and principally to improve the resilience of member 27 a reverse bend 27' is included therein.

At the end of the spring blade 24 opposite that secured by the rivets 22 and 22, movable switch contacts 33 and 33' are secured to the upper and lower surfaces respectively of the blade between the lower and upper switch contacts and 21. When the switch is in normal position as shown in Fig. l the compression member is slightly above the plane of the spring blade 24 and the movable switch contact 32' is seated upon the lower switch contact 29. Current therefore flows between the screw terminals 17 and 18.

To actuate the switch, a downward force is applied to the outer end 26a of the lever arm 26, to deflect the free end of the lever arm and accumulate spring energy in the actuator. As a result, a progressively increasing downward force is exerted on the end of the compression member 30 until it is deflected substantially into the plane of the blade. In such position the compression member 30 causes the entire system to be in un stable equilibrium and its resisting forces collapse rapidly. The resilient actuating force accumulated in the lever 26, however, decreases only in proportion to change in deflection. Accordingly, the spring force accumulated in the lever arm 26 reliably and forcibly carries the entire system through its unstable condition and quickly snaps member 30 through the plane of the blade. The downward movement of the compression member causes an upward snap of the free end of the spring blade, upon which are mounted the movable switch contacts 33 and 33. The movable switch contact 33' is thereby carried into engagement with the upper switch contact 21 and current flows between the screw terminals 17 and 19.

Reverse actuation of the switch is effected by withdrawing actuating force from the lever arm 26, whereupon the arm moves upwardly toward its normal unftexed position, drawing the compression member through the plane of the blade and causing the blade to snap downwardly. Accordingly, the external actuating means may advantageously comprise a cam 34, shaped to provide a sudden drop-off and permit a fast, decisive return movement of the lever arm. A more complete description of the cam is set forth in connection with the embodiment of Figs. 4-6.

In the embodiment illustrated in Figs. 4-6, a compression member (which may be relatively rigid and could if desired, be of insulating material) is pivotally, rather than integrally, attached to the remainder of a spring blade 41. All of the other elements of this embodiment,

however, are identical in function and design to those of the previous embodiment and hence are given identical reference numbers. The compression member 40 is formed from fiat stock with a foot 42 extending upwardly at one end. In either side of the foot 42 notches 43 are formed which engage the spring blade 41 at the end of a rectangular longitudinal cut-out section 44 nearest the movable switch contacts 33 and 33'.

Exterior actuating means for the switch comprises a rotating cam 45, similar to cam 34 of Fig. 2, which has a spiral cam surface 46 and a drop-oif 47 on its periphery. The end portion 26a of the actuator lever arm is positioned such that as the cam rotates it gradually deflects the lever arm 26 until sufiicient spring force is accumulated to cause the compression member to snap from the position of Fig. 4 to that of Fig. 5. As described in reference to the previous embodiment, the movable switch contacts 33 and 33 are thereby snapped upwardly to make and break the respective circuits. When the drop-off 47 rotates over the lever arm, the compression member 40 is returned rapidly through the plane of the blade and the movable switch contacts 33 and 33' are decisively snapped back to the position shown in Fig. 4.

The new switch is especially suited for use with a very slowly rotating cam, for example, as where it is required to transfer current from one circuit to another at widely spaced intervals of time. In accordance with the invention, such transfer is reliably accomplished with a decisive snap action, in a switch assembly of simplified and inexpensive design and without incorporating costly curves or linkages into the structure of the switch or requiring expensive preforming operations.

It should be understood that the specific forms of the invention herein illustrated and described are intended to be representative only, as certain changes may be made therein without departing from the clear teachings of the disclosure. Accordingly, reference should be made to the following appended claims in determining the full scope of the invention.

I claim:

1. A snap action switch comprising a spring blade, an actuator, and a support, said spring blade including a compression member, a tension member and an end portion adapted to move into and out of contact with a switch contact, said tension member being fixedly secured to said support, said compression member being engaged by said actuator, said actuator including a connecting member and an actuating lever arm, said actuating lever arm being resiliently mounted at one end to said support and having a free end resilient in a direction normal to the blade, said connecting member exerting a compressive spring force upon said compression member in a direction substantially longitudinally of the latter and causing said compression member to snap said spring blade when said free end of said actuating arm is deflected in a direction normal to the blade to a predetermined extent to increase the compressive force exerted by the actuating arm against the compression member, thereby moving said end portion of the blade relative to said switch contact.

2. A snap action switch according to claim 1 wherein said connecting member is resilient and depends substantially centrally from said lever arm.

3. A snap action switch comprising a blade support, a spring blade fixed at one end to said support, a compression member attached at one end to said blade and having a free end projecting toward the fixed end of the blade. said compression member having a range of unstable positions near the plane of the blade when under compression and being movable through the plane of the blade for snapping the blade from one position to another, and an actuator including an actuating lever arm resiliently mounted at one end to said support and having a free end resiliently deflectable in a direction normal to the blade. said actuator having a portion in engagement with the free end of said compression member, said actuator causing said compression member to move through the plane of the blade when the free end of said actuating lever arm is deflected in a direction normal to the blade to a predetermined extent to increase the compressive force exerted by the actuating lever arm against the compression member and to move said compression member into said range of unstable positions.

4-. A snap action switch according to claim 3 which includes a member having a cam surface movable against said free end of said actuating lever arm and configured to gradually deflect said actuating lever arm from a starting position until said compression member is moved into said range of unstable positions, and configured to permit the return of said actuating lever arm suddenly to said starting position.

5. A snap action switch comprising a normally substantially planar spring blade, an actuator, and a support, said spring blade including a compression member, a tension member, and an end portion adapted to move into and out of contact with a switch contact, said tension member being fixedly secured to said support and substantial-1y collaterally positioned relative to said compression member, said compression member projecting substantially longitudinally relative to said blade into a cut-out area therein, said tension member also being substantially longitudinally disposed relative to said blade and substantially defining said cut-out area therein, said compression member being engaged by said actuator, said actuator including a connecting member and a resilient actuating lever arm, said actuating lever arm being resiliently mounted at one end to said support and having a free end resilient in a direction normal to the blade, said connecting member exerting a compressive spring force upon said compression member in a direction longitudinally of the latter and being movable to force said compression member through the plane of the blade when said free end of said actuating lever arm is deflected in a direction normal to the blade to a predetermined extent thereby moving said end portion of the blade relative to said switch contact.

References Cited in the file of this patent UNITED STATES PATENTS Riche Feb. 13, 1940' Kaminky Mar. 11, 1947 Raney Sept. 8, 1953 McClain July 3, 1956 Happe Apr. 16, 1957 Hager Aug. 5, 1958 FOREIGN PATENTS Great Britain June 27, 1951

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