GB1101677A - Compensated thermomotive flasher - Google Patents

Abstract

1,101,677. Thermal switches; electromagnetic switches. LEHIGH VALLEY INDUSTRIES Inc. 11 June, 1965, No. 24769/65. Heading H1N. ' The rate of cycling of a thermal " flasher " switch comprising a snap - acting vane 10 stressed by a thermallyexpansible ribbon 20, such as that disclosed in Specification 761,713, is prevented from rising unduly with rise in applied voltage by means of a shunt circuit completed by electromagnetically - closed contacts. The support 41 for vane 10 comprises magnetic material carrying a winding 35 and an armature 40 mounted on a spring blade 42. A contact 23 on ribbon 20 co-operates with a fixed contact 24 on a spring metal yoke 25 clipped over the winding 35, one end of which is connected to the yoke 25 while the other end is connected to . a rivet (21, Figs. 1 and 3, not shown), holding the terminal prong 14 to insulating base 12. A second terminal prong 16 is held by a rivet 22 on which the support 41 is secured. A circuit thus extends from prong 14 via winding 35 contacts 24, 23 and ribbon 20 to the support 41 and hence prong 16. At a predetermined voltage the armature 40 is attracted and engages a rivet 45 connected to a resistive ribbon 50 whose other end is connected to rivet 21. Thus ribbon 50 is put in parallel with the circuit of ribbon 20 to reduce the current therethrough and thus the cycling rate of contacts 23, 24. In an alternative embodiment (Fig. 5, not shown), the shunt circuit is closed by a contact (56) on a bimetal strip (55) heated by a coil (65). The co-operating contact (61) of this embodiment is carried on a further bimetal strip (60) to compensate for changes in ambient temperature.