GB432909A - Improvements in or relating to temperature regulating devices - Google Patents

Abstract

432,909. Thermal switches. IGRANIC ELECTRIC CO., Ltd., 147, Queen Victoria Street, London, and WRIGHT, S. R., 113, London Road, Bedford. Feb. 6, 1934, Nos. 3861, 4765, 14775, 14916, and 23144. [Class 38 (v)] [See also Group XIII] Temperature-regulating apparatus comprises electric heating means and a control lever 14 actuated by a thermally responsive device 11, the movement of which is transmitted to the lever by an element 13 pivoted, on the lever at 16. On opposite sides of the pivot, by surfaces preferably substantially at right; angles to each other, the element 13 abuts respectively against the thermal actuator and a fixed abutment 17. The latter is adjustable to determine the regulated temperature and is preferably associated with an indicating scale. The control lever may carry a main contact and auxiliary contacts whereby the heating elements and a signal lamp may be controlled in various ways, and in one modification the lever carries a flexibly mounted auxiliary contact actuated by an adjustable abutment thereon. The indicating lamp may illuminate a transparent scale in the adjusting knob 19. As shown in Fig. 2, the thermal actuator is a compound element consisting of a perforated tube enclosing a rod, the inner and outer surfaces of the tube and the surface of the rod being coated with a black material such as graphite enamel; the rod and tube are of metals of different coefficients of expansion, e.g. nickel steel and aluminium. The adjusting member is a screw 17 and to permit of calibration its bush 21a has a hexagonal head and a lock nut 23 whereby it may be adjustably rotated and clamped in the support 22. The lever 14 carries an insulated main contact 5a riveted thereon with a member 5 carrying auxiliary contacts 5b, 5c. These contacts each engage spring-pressed contacts fixed on the insulating base 26. In the modified construction diagrammatically shown in Fig. 7, the contact 5b is spring- mounted on the member 5 and the main contact 5a is insulated from the said member which carries a spring 46 and contact 44 co-operating with a fixed contact 45; an adjustable abutment 42 is engaged by a tail piece 41 on the auxiliary contact 5b to separate the contacts 44, 45 when it engages its fixed contact 4.