GB202648A - Thermostatic switch - Google Patents

Abstract

202,648. Svensson, I. V. Aug. 18, 1922. [Convention date]. Void [Published under Sect. 91 of the Act]. Thermal cut-outs for use with electric irons &c. which are mounted within the socket member 1 of a plug coupling, have a fixed contact 11 connected to one of the pockets 12 which co-operates with a movable contact 10 attached to a metal block 9. The block 9 is mounted on a shaft 7, a thin layer of solder 8 being run in between the two members, Fig. 5. The shaft 7 is rotatably mounted within the porcelain body 1 and bears at one end against a metal strip 6 attached to an incoming lead 5. The other end of the rod 7 has an external operating 14 which carries a spring pawl 7 engaging one of a number of recesses 16 in the cover 17, Fig. 1, to hold the shaft in its adjusted position. A spring 13 is secured between a fixed point and a depending arm of the contact 10, and when the iron &c. reaches a predetermined temperature, the conducted heat melts the solder 8 and allowing the spring 13 to move the arm 10 to the dotted position, Fig. 2, in which the heating circuit is interrupted at 10, 11. When the solder 8 has solidified the cut-out may be re-set by rotating the handle 14, the shaft 7 carrying with it the block 9 and contact 10. In a modified form the layer 8 of fusible material is dispensed with, the member 9 fitting friction tight on the shaft 7 and being composed of material of higher coefficient of expansion than the shaft so that on heating the greater expansion of the outer member enables it to be rotated by the spring 13 to interrupt the heating circuit. In a further modification a rectilinearly movable contact member may be employed.