GB562020A - Improvements relating to safety switches for electrically heated appliances - Google Patents

Abstract

562,020. Thermal switches. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 10, 1942, No. 17570. Convention date, Dec. 16, 1941. [Class 38 (v)] A safety device for an electric iron or other appliance which opens the circuit sometime after the handle is released comprises a thermally-actuated or thermally-tripped switch 21, 22 the heating means of which is short-circuited at 37, 38 when a manually-operated lever 47 or like device is depressed against the action of a return spring. In the form shown the device is mounted in the handle of an iron and when the handle is gripped or the iron is stood on end, a projection 51 closes contacts 37, 38 and a projection 52 moves a latch 36 allowing contacts 21, 22 to close. A circuit to the heater of the iron is thus closed passing through both pairs of contacts in series. If the handle is now released, contacts 37, 38 open but the current to the heater can still pass through contacts 21, 22 and the bimetallic strip 34 carrying the contact 22. The bimetallic strip 34 is thus heated and after a short time interval bends upwards into the position shown where it is held latched, the contacts 21, 22 opening to break the heater circuit. In a modification, Figs. 6-11 (not shown) the strip 34 consists of a spring and is not bimetallic. It is held closed by a bimetallic latch, which is short circuited by the contacts 37, 38. Specifications 144,767, [Class 38 (i)], and 557,024 are referred to.