Improvements in electrically-heated devices

摘要

827,727. Electric cooking vessel and immersion heater. WALTON, G. W. July 30, 1956 [Feb. 7, 1956], No. 3717/56. Class 39(3) [Also in Groups XXXV and XXXVI] An electrically heated saucepan 167 (Fig. 19) has a metal capsule 158 secured to its inner or outer surface, for example in one of the three positions shown, either resting on the saucepan bottom or secured to the side by a spring 168 or it may be riveted or welded to the pan. The capsule contains an electric resistance heating element comprising two wires of material having a high temperature coefficient of resistance e.g. of nickel or tugnsten and two wires not having this characteristic e.g. of nickel chrome forming a bridge for themostatic control purposes (see Group XXXV). The wires may be wound on mica and the copper capsule may be used as an immersion heater and stirrer. Figure 21 shows a saucepan with the resistor elements incorporated into its structure between the pan bottom and a baseplate 172, a serpentine heater wire 42 being embedded in an annular mass 173 of compacted magnesia, and the temperature-variable resistance element 158 being located at the centre. Various methods of using the heating resistance as part of the bridge network are described and illustrated, and the resistors forming the bridge may be chosen and located to effect control of the rate of heating as well as of the maximum temperature.