US3594673A

US3594673A - Flasher switch

Info

Publication number: US3594673A
Application number: US883914A
Authority: US
Inventors: Cleon F Frey
Original assignee: INT FLASHER CORP
Current assignee: INT FLASHER CORP
Priority date: 1969-12-10
Filing date: 1969-12-10
Publication date: 1971-07-20
Anticipated expiration: 1988-07-20

Abstract

A ''''hot-wire''''-type thermally responsive flasher switch in which a channel-shaped support member carries a snap vane at one of the support member ends, the vane spanning the flange portions of the support member. A thermal expansion wire extends the length of the support member and within its channel configuration and exerts a buckling force on the vane intermediate the vane''s ends. The support member carries a stationary electrical contact and the free end of the snap vane carries a cooperating movable contact.

Description

United States Patent [72] Inventor Cleon F. Frey Sebastian, Fla. [21] Appl. No. 883,914 [22] Filed Dec. 10,1969 [45] Patented July 20, 1971 [73] Assignee International Flasher Corporation Bayamon, P.R.

[54] FLASHER SWITCH 3 Claims, 3 Drawing Figs.

[52] 11.8. CI 337/136, 337/ 140 [51 Int. Cl ..1-101h 37/50 [50] Field oiSearch 337/131, 1.15,136,138,140, 391, 395

[56] References 'ited UNITED STATES PATENTS 2,074,345 3/1137 Schmidingm 337/141) FOREIGN PATENTS 1,034,599 4/1953 France 337/131 1,030,261 5/1966 Great Britain 337/ 1 35 Primary ExaminerBernard A. Gilheany Assistant Examiner- Dewitt M. Morgan Attorney-Woodard, Weikart, Emhan & Naughton ABSTRACT: A hot-wire"-type thennally responsive flasher switch in which-a channel-shaped support member carries a snap vane at one of the support member ends, the vane spanning the flange portions of the support member. A thermal expansion wire extends the length of the support member and within its channel configuration and exerts a buckling force on the vane intermediate the vane's ends. The support member carries a stationary electrical contact and the free end of the snap vane carries a cooperating movable contact.

- F LASI'IER SWITCH BACKGROUND OF TH E INVENTION The invention relates generally to hot-wire-type flasher switches and more particularly to such a switch having good load-carrying characteristics and a minimal number of parts, but characterized by a rugged construction resisting damage and calibration setting alteration caused by rough handling or dropping of the switch during transport, storage or installation.

In vehicles it has been found desirable to provide means for continuously flashing at least two lights at the front end of the vehicle and two lights at the rear end during emergency conditions or during certain types of operation of the vehicles. Examples include local delivery trucks, ice-cream-vending trucks, mail trucks, stalled automobiles and highway maintenance vehicles. While various types of flasher switches are utilized as vehicle turn signal controls, the operation of four or more bulbs of comparatively high wattage in a continuously flashing manner imposes loads which such flasher switches are unable to carry. While it is desirable for hazard flashers to have good load-handling characteristics, it also remains important that such devices be of reliable, rugged, inexpensive construction.

SUMMARY The inventive concept utilizes a channel-shaped support member, to enclose along its length a thermally expansible tension wire anchored at one end to the channel member and with its other end attached centrally to a snap vane cantilever mounted on one end of the channel member. Cooperating electrical contacts are carried by the vane and the channel member. The tension wire extends centrally through the enclosure formed by the channel member and is attached centrally to the snap vane which spans the space between the side flanges of the channel member thus providing a compact, rigid construction resistant to exteriorly inflicted blows or shock.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a flasher switch embodying the present invention with the cover shown in section.

FIG. 2 is a top plan view of the switch shown in FIG. 1 with the cover removed.

FIG. 3 is a side view of the structure shown in FIG. 1 with a schematic illustration of a typical hazard lamp circuit shown schematically and incorporating the flasher switch.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, particularly FIG. 1, the flasher switch includes a circular base plate 10, formed of suitable electrical insulating material, the base being removably snapped into an accommodating groove at the base of a tubular metal cover or housing 11.

Electrical terminal members

12 and 13 extend from one side of the base and the terminal members are provided with connecting tabs 12a and 13a which extend through the base and have electrically connected to them components to be subsequently described.

An electrically conductive support member extends from the other side of the base 10 and is channel shaped having

side flange portions

14 and 16 and a central web portion 17. As may be seen in FIG. 1, the lower end of the flange portion 14 is electrically connected to the portion 120 of the terminal member 12. The central web portion has its lower end 17a turned inwardly between the flanged portions at the lower end of the support member. The lower end of the side flange portion 16 is riveted to the base 10 as indicated at 18 but is not electrically connected to the terminal 13. At its free end the support member flange 16 has a sidewardly extending tab 19 to which is riveted a resilient, electrically conductive vane or snap member 21. The vane 21 is formed with a slight concavoconvex configuration and has a stable, unstressed position shown in FIG. 1, in which the face of the vane nearest the baseplatc I0 is convex. The vane substantially spans the distance between the two

flange portions

14 and 16 and its upper face engages the tab 22 which extends from the upper end of the flange portion 14. The vane is provided with a series of radial grooves 23, pressed into its surface, and with a central aperture 24 (FIG. 2). On its underface, and adjacent its free end, the vane carries a movable electrical contact 26 (FIG. 1) which cooperates with a stationary contact 27.

The stationary contact 27 is formed by a tab extending inwardly from a plate 28 which overlies a layer of electrical insulating material 29 (FIG. 3), the plate 28 being held rigidly on the adjacent portion of the flange 14 of the support member by means of the tabs 2811, with the layer of insulating material 29 interposed between the plate 28 and the flange 14. The plate 28 has a sidewardly extending portion 28b through which is secured a portion of the thermally expansible wire to be subsequently described.

The extending tab 19 ofthe flange 16 has secured to it a tensioned thermal expansion wire31, the wire extending over the top face of the vane 21 as shown in FIG. 2 and through the central aperture 24 in the vane. As may best be seen in FIG. 1, the wire extends to the tab 17a and is fused in a ceramic bead 30 which is held in an undersize aperture in the tab, the bead thus serving as an anchoring point for the wire 31. An untensioned continuation of the wire, identified at 310 in FIG. 1, extends from the bead and is held spaced away from the adjacent flanges by a member 32 extending from the flange 16, the wire 310 being insulated from electrical contact with the member 32 by means of a small folded electrically insulating member 33. The wire 31a is coiled to permit it to be of extended length and its upper end is secured and electrically connected to the extending portion 28b of the plate 28 as will be evident from FIG. 3. The coiled portion 31a of the wire 31 serves as electrical ballast 'to reduce the current flow through the wire 31 when an electrical potential is connected across the

terminals

12 and 13. A wire 36 (FIG. 1) is electrically connected to the tab 13a of the terminal 13 and is electrically connected, at its upper end, to the plate 28. An electrical circuit is thus completed from the terminal 13 to the stationary contact 27 and, similarly, an electrical circuit is complete from the terminal 12, through the support member itself to the upper end of the wire 31, through the wire 31 and its coiled portion 310 to the plate28 and thence back to the terminal 13. When the vane 21 is released by elongation of wire 31, so that its face adjacent the base plate is concave, the movable contact 26 will snap into engagement with the stationary contact 27 and the circuit through the wire 31 will be shunted since current can then flow directly across the vane 21 to the support member and to the terminal 12, the

terminals

12 and 13 then being directly connected together through the

engaged contacts

26 and 27.

In operation, referring to FIG. 3, the terminal 13 may be connected to one side of a bank of hazard lamps indicated generally at 41, the lamp circuit being energized by a battery or other source of electrical power 42 with control of the circuit being accomplished by the switch 43 which has one side connected to the flasher switch terminal 12. When the switch 43 is closed, the electrical potential thereby impressed across the

terminals

12 and 13 causes a small amount of current to flow through the wire 31. The wire 31 is, of course, initially under tension and holds the vane in buckled condition as shown in FIG. 1 in which the

contacts

26 and 27 are separated. The flow of this relatively small amount of current through the wire 31 causes a temperature rise in the wire, and a thermal elongation of the wire, which permits the vane 21 to snap to an unstressed position in which its face nearest the base 10 is concave and the contact 26, carried at the free end of the vane, snaps into engagement with the contact 27. Closure of

contacts

26 and 27 electrically shunts the wire 31 and full load current passes through the contacts and

terminals

12 and 13. Shunting of the wire 31 permits it to cool and the consequent thermal shrinking of the wire in length again buckles the vane 21 to its position of FIG. 1 in which the

contacts

26 and 27 are separated. The cycle then begins anew and the contacts are alternately closed and opened for as long as the required electrical potential is across the

terminals

12 and 13.

The cycling speed of the flasher may be adjusted by bending the tab 22 either toward or away from the contact 27, which establishes the maximum buckled position of the vane 21. The percent of the total cycle time in which the

contacts

26 and 27 are closed can be varied by bending the tab 17a so as to adjust the tensile stress on the wire 31 when the vane is in buckled condition. The calibration bending of the tab 17a can be con veniently accomplished by inserting a tool at the aperture indicated at 44 in FIG. 3, this access aperture resulting from a cutaway portion of the side flange 14 at the base of the support member. Since the wire 31 passes through the central aperture 24 in the vane, the force exerted by the wire is applied centrally on the vane and this arrangement obviates the necessity for welding or otherwise securing an abutment on the vane to which the wire can be attached. The channelshaped support member carrying the contacts and the vane, with the tension wire substantially enclosed by the support member, minimizes the effect of external forces (as might be applied, for example, upon dropping of the assembly) on the calibration settings, that is, the stability of operation of the switch.

lclaim:

l. A hot-wire-type flasher switch comprising a baseplate with electrical terminal members extending from one side of the base, an electrically conductive support member extending from the other side of the base and electrically connected to one of the terminal members, said support member having a channel-shaped configuration with a portion of the web section turned inwardly adjacent the baseplate to form a tab extending between the two opposite flange sections of the channel-shaped support member, a resilient electrically conductive vane cantilever mounted on one of said flange sections adjacent the free end of the support member and substantially spanning the distance between the two flange sections, said vane being formed with a concavo-convex configuration having a stable unstressed position in which its face nearest said baseplate is concave but having a stress-buckled position in which its face nearest the baseplate is convex, a tensioned thermal expansion wire fastened to said baseplate tab and to an intermediate portion of said vane for holding the vane in its buckled position at normal temperature but permitting the vane to snap to its stable position at an elevated temperature, a stationary electrical contact mounted on but electrically insulated from the other of said support member flange sections, a cooperating electrical contact carried by said vane adjacent its free end and adapted to engage said stationary contact when said vane has snapped out of its said buckled position to its said stable position, and wires electrically connecting another of said terminal members with said stationary contact and with the end of said tensioned wire remote from its attachment to said vane, whereby upon imposition of an electrical potential of sufficient magnitude across said terminal members said tensioned wire will elongate permitting said vane-carried contact to engage said stationary contact thereby electrically shunting said tensioned wire to again separate said contacts to repeat the contact engagement and disengagement cycle.

2. A flasher switch as claimed in claim 1 in which said support member has an extending tab adjacent to but on the opposite side of said vane from said stationary contact, said tab functioning as a stop defining the maximum buckled position of said vane.

3. A flasher switch as claimed in claim 1 in which said tensioned thermal expansion wire extends through an aperture formed centrally in said vane, the extending end of said wire being secured to said support member whereby the wire applies buckling force to said vane adjacent said central aperture.

Claims

1. A hot-wire-type flasher switch comprising a baseplate with electrical terminal members extending from one side of the base, an electrically conductive support member extending from the other side of the base and electrically connected to one of the terminal members, said support member having a channel-shaped configuration with a portion of the web section turned inwardly adjacent the baseplate to form a tab extending between the two opposite flange sections of the channel-shaped support member, a resilient electrically conductive vane cantilever mounted on one of said flange sections adjacent the free end of the support member and substantially spanning the distance between the two flange sections, said vane being formed with a concavo-convex configuration having a stable unstressed position in which its face nearest said baseplate is concave but having a stressbuckled position in which its face nearest the baseplate is convex, a tensioned thermal expansion wire fastened to said baseplate tab and to an intermediate portion of said vane for holding the vane in its buckled position at normal temperature but permitting the vane to snap to its stable position at an elevated temperature, a stationary electrical contact mounted on but electrically insulated from the other of said support member flange seCtions, a cooperating electrical contact carried by said vane adjacent its free end and adapted to engage said stationary contact when said vane has snapped out of its said buckled position to its said stable position, and wires electrically connecting another of said terminal members with said stationary contact and with the end of said tensioned wire remote from its attachment to said vane, whereby upon imposition of an electrical potential of sufficient magnitude across said terminal members said tensioned wire will elongate permitting said vane-carried contact to engage said stationary contact thereby electrically shunting said tensioned wire to again separate said contacts to repeat the contact engagement and disengagement cycle.