GB1493978A - Thermoelectric flasher arrangements - Google Patents

Abstract

1493978 Thermal flasher switch WESTFALISCHE METALL INDUSTRIE KG HUECK & CO 8 April 1975 [9 April 1974] 14364/75 Heading H1N A flasher switch comprises an element 4, biased to move in direction A but retained by a thermosensitive element 7, and a resilient switching element 1 carrying contacts 2, 3 and mechanically connected to the biased element 4 by an over-centre spring 6 which is insulated from the element 4 by a block 6a. When the switch FR is closed current flows from supply terminal 49, through the switching element 1, contacts 2, 2a, thermosensitive element 7 (which it heats and expands) and biased element 4 which is connected via a winding 8 to the lamps BL. The expansion of element 7, which is a heater wire, allows biased element 4 to move towards the switching element 1 until the spring 6 moves over-centre and snaps the element 1 across to make contact between 3 and 3a (Fig. 2, not shown). Simultaneously the current through winding 8 attracts a biased armature 11 to make contact with 2a thus providing a circuit to an indicator lamp CL. In this position the flasher lamp current no longer passes through the heater wire 7 so that the lamps glow with full brilliance until the heater cools sufficiently to separate contacts 3, 3a as the biased element 4 is drawn back, the following movement of switch element 1 being prevented by a stop 5 (Fig. 3, not shown). Further cooling and withdrawal of the heater wire results in the spring 6 and hence switch element 1 being returned to the initial position. As the timing of both light and dark periods is determined by the cooling of the heater wire, the device is virtually independent of voltage. Constructional details are given (Figs. 4 and 5, not shown).