US2907850A

US2907850A - Snap action devices

Info

Publication number: US2907850A
Application number: US664053A
Authority: US
Inventors: Colombo George
Original assignee: HODA CORP
Current assignee: HODA Corp
Priority date: 1957-06-06
Filing date: 1957-06-06
Publication date: 1959-10-06
Anticipated expiration: 1976-10-06
Also published as: FR1196527A; DE1286639B; GB850983A

Description

cs. coLoMBb SNAP ACTION DEVICES Oct. 6, 1959 2 Sheets-Sheet 1 Filed June 6.1957

FIG.2

ATTORNEY Filed June 6, 1957 2 Sheets-Sheet 2 INVENTOR.

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ATTORNEY g United States Patent SNAP ACTION DEVICES George Colombo, East Rockaway, N. Y., assignor, by mesne assignments, to Hoda Corporation, Great Neck, N.Y., a corporation of New York Application June 6, 1957, Serial No. 664,053

4 Claims. I (Cl. 200122) This invention relates to snap action electric switches and, more particularly, to a novel snap action thermostatic flasher or relay in which the making and breaking of an electric heating circuit for the flasher controls the closing and opening of a second or relay-controlled electric circuit which is electrically independent of the heating circuit.

In US. Patent No. 2,756,304 issued to James W. Welsh on July 24, 195 6, there is shown and described a snap action vane electric switch including a substantially flat vane of electrically conductive resilient material having a pair of linear deformations extending along one diagonal and with their inner ends spaced to leave a central area of the vane undeformed. These deformations impart an initial set or bend to the vane to shape the latter into a shallow V whose apex lies along such diagonal.

To form a snap action switch, a strip or wire of high electrical resistance has its ends secured to the vane at the outer ends of such one diagonal, the heating wire or strip being attached to the vane in the cold, contracted condition in such manner as to stress-deform the vane to bend about the other diagonal; When this strip or wire is heated, it expands and allows the vane to snap back to a restored position in which the vane is bent about such one diagonal. When the strip contracts, the vane is snapped back to the stress-deformed position.

If a vane of this type --is fixedly mounted at a point on an elliptical line of stress concentration loci laterally of the deformations, there is a substantial amplitude of movement of parts of the vane relative to the mounting point during snapping of the vane, as well as substantial relative movement of the vane and the intermediate portion of the pull strip or wire. Such movement may be effectively utilized to provide a snap action switch by mounting switch contacts on the vane or on the pull strip, these contacts being cooperable with other contacts fixed relative to the vane mounting point.

Snap action switches of this type have been used extensively as flashers in automotive vehicle signalling systems, the usual circuit arrangement including the pull strip and vane as part of the electric heating circuit. In some instances, the pull strip is heated by a high resistance wire wrapped therearound instead of directly by the flow of electric current therethrough.

The present invention is directed to a snap action vane relay in which the making and breaking of the electric heating circuit for the pull strip effects a corresponding intermittent operation of a second relay controlled circuit electrically isolated from the heating circuit. Thereby, a heating circuit operating at one voltage may be used to control operation of a second circuit operating at another voltage. Alternatively, a DC heating circuit may be used to control an AC. signalling circuit, or vice versa.

For an understanding of the invention principles, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawing.

1 current intermittor embodying the invention;

Fig. 2 is a side elevation view of the switch with the cover in section;

Fig. 3 is an end elevation view of the switch, partly in section; and

Fig. 4 is a bottom plan view of the switch.

Referring to the drawing, the switch is illustrated as including a substantially rectangular and flat dielectric base 10 to which four

terminals

11, 12, 13 and 14 are secured by rivets 11', 12' 13 and 14' extending through the base. A removable cover 15 seats on a shoulder 16 around the periphery of base 10.

The switch includes a snap-action vane 20, of electrically conductive resilient metal, having a pair of linear deformations 21 disposed in spaced relation along one diagonal so as to leave the central area of the vane 20 undeformed. Vane 20 has a restored or naturally bent position as a shallow V about the diagnal through deformations or bosses 21.

The vane is bent and stress-deformed about the other diagonal by a pull strip 30 of metal having a relatively high coeflicient of thermal expansion. Strip 30 is secured to vane 20 at each end of the first diagonal, the strip beingsecured to the vane in the cold contracted condition. Heating of strip 30 is effected by a high electrical resistance wire 35 wrapped about the center part of the strip.

Vane 20 is fixedly mounted on one end of'a bracket 22, of electrically conductive metal, whose other end is bent, as at 23, and electrically and mechanically secured to rivet 11'. A dielectric sleeve 24 is mounted on bracket 22 intermediate the ends of the latter. A band 26 of electrically conductive metal is wrapped around sleeve 24 and carries a contact 25 facing a contact 27 on vane 20. The end of strip 26 is electrically and mechanically connected to rivet 12'. Contacts 25-27 are normally open.

One end of wire 35 is electrically and mechanically connected to a C-shape bracket 31 electrically and mechanically connected to rivet 13'. The other end of wire 35 is electrically connected to a contact 40 mounted on vane 20, a dielectric separator 41 being interposed between contact 40 and vane 20. Contact 40 is normally engaged with a contact 45 electrically connected to a C- shape bracket 46 electrically and mechanically secured to rivet 14'.

As schematically illustrated in Fig. 1, terminal 11 is connected to the ungrounded terminal of a battery 50 whose other terminal is grounded. Terminal 12 is connected to ground through a load 51. Terminal 13 is connected through a switch 52 to a grounded battery 53. Terminal 14 is connected to ground through a load 54.

If switch 52 is closed, current flows through heater wire 35, heating strip 30. As the strip expands, vane 20 snaps from the illustrated stress-deformed position to its restored position bent about bosses 21. Such snapping separates contacts 40-45 to open the first or heating circuit, and engages contacts 25-27 to close the second or relay-controlled circuit. With interruption of the heating current, strip 30 cools and contracts and eventually snaps vane 20 back to the stress-deformed position to snap contacts 25-27 apart and snap contacts 40-45 into engagement. The heating circuit is thus re-closed and the cycle repeats.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the invention principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. A snap action electric relay comprising, in combi- 3 nation, adielectric mounting base; a substantially fiat vane of electrically conductive resilient material having a substantially linear preset deformation extending thereacross, said vane having a restored position in which it is bent about said-deformation; mounting means secured to said base and fixedly secured to said vane at a mounting point on the latter spaced laterally from said deformation; a thermostatic operator secured at each end to said vane adjacent the outer ends of said deformation and, in the cold and contracted condition, constraining said vane to a stress-deformed position in which the vane is bent about a 'line at an angle to said deformation; said vane, upon heating and expansion of said operator, snapping to the restored position and, upon cooling and contracting of said operator, snapping to the stress-deformed position; portions-of said vane spaced from said mounting point moving substantially relative to said base during snapping of the vane; a first contact mounted on a movable part of said vane and insulated therefromrand a second contact fixed relative to said base; said firsttand second contacts being engaged in the stress-deformed position of said vane and snapped apart upon snapping of said vane to the restored position; and a third contact mounted on a movable part of said vane and electrically connected thereto, and a fourth contact fixed relative to said base; said third and fourth contacts being disengaged in the stress-deformed t position of said vane and snapped into engagement upon snapping of said vane to the restored position; whereby, upon heating of said operator, said third and fourth contacts will be alternately closed and opened as said vane snaps to the restored position and then back to the stress deformed position.

2. A snap action electric relay comprising, in combination, a dielectric mounting base; a substantially fiat vane of electrically conductive material having a substantially linear preset deformation extending thereacross, said vane having a restored position in which it is bent about said deformation; an electrically conductive mounting bracket secured to said base and fixedly electrically and mechanically secured to said vane at a mounting point on the latter spaced laterally from said deformation; a thermostatic operator secured at each end to said vane adjacent the outer ends of said deformation and, in the cold and contracted condition, con- I straining said vane to a stress-deformed position in which the vane is bent about a line at an angle to said deformation; said vane, upon heating and expansion of said operator, snapping to the restored position and, upon cooling and contracting .of said operator, snapping to the stress-deformed position; portions of said vane spaced from said mounting point moving substantially relative to said base during snapping of the vane; a first contact mounted on a movable part of said vane and insulated therefrom and a second contact fixed relative to said base; said first and second contacts being engaged in the stress-deformed position of said vane and snapped apart upon snapping of said vane to the restored position; and a third contact mounted on a movable part of said vane and electrically connected thereto and a fourth contact fixed relative to said bracket and insulated therefrom; said third and fourth contacts being disengaged in the stress-deformed position of said vane and snapped into engagement upon snapping of said vane to the restored position; whereby, upon heating of said operator, said third and fourth contacts will be alternately closed and opened as said vane snaps to the restored position and then back to the stress-deformed position.

3. A snap action relay as claimed in claim 2 in which said base has four terminals; said first contact is electrically connected to a first one of said terminals; said bracket is electrically connected to the second of said terminals; and said second and fourth contacts are electrically connected to the third and fourth of said terminals, respectively.

4. A snap action relay as claimed in claim 3 including a high electrical resistance conductor Wound on said operator and connected between said first terminal and said first contact.

References Cited in the file of this patent UNITED STATES PATENTS