GB1116915A - Snap action electric device - Google Patents

Abstract

1,116,915. Thermal switches. TUNG-SOL INDUSTRIES Inc. 21 April, 1966 [26 April, 1965], No.17580/66. Heading H1N. A snap-action thermal " flasher " comprises a resilient conducting vane provided with an inherent curvature about one axis caused by one or more ribs tapering from a maximum height and/or width adjacent the periphery of the vane to a minimum height and/or width adjacent the centre of the vane, a pull ribbon secured to the vane under tension so as when cold to bow the vane away from its inherent curvature to buckle it about an axis 90 degrees to the said one axis, and when heated, expanding to allow the vane to snap back to its inherent curvature. In Fig. 9, the vane 62 carries a contact 78 which engages a fixed contact 77 mounted on a post 76 when ribbon 72 is hot. Ribbon 72 is heated by an insulated coil 74 which is shorted by the vane when contacts 77, 78 are closed so cooling occurs and vane snaps to open contacts 77, 78. Platforms 70 on the vane prevent coil 74 from contacting the vane when the ribbon is cold, but allow the coil 74 to contact the vane when the ribbon has expanded and the vane has snapped to its inherent curvature to promote cooling. In a modification (Figs. 13-16), the vane carries a contact which engages the fixed contact when the ribbon is cold, and the ribbon is heated by current passing through it. The movable contact may be mounted on the ribbon. The vane may be rectangular, square, circular, or oval. One or more holes may be provided at the centre of the vane. The ribbon overlies the convex side of the inherent curvature, and the ribs may be concave or convex on the side facing the ribbon.