GB203244A - Improvements in and relating to electric heating devices - Google Patents

Abstract

203,244. British Thomson-Houston Co., Ltd., (International General Electric Co., Inc.). Nov. 29, 1922. Wire resistances mounted on grooved surfaces. -In electric heaters of the kind wherein the heating-element is arranged in a spiral groove in the face of a disc of refractory insulating-material, the groove 11, Fig. 1, is in the form of a polygonal spiral, for example a double spiral hexagon, with overhanging portions 13 and corresponding recesses 14 at the corners of the polygon to retain the heating-element in position. The heating. element may be rigid or flexible and is shown in Fig. 3 as a helically coiled wire 12. The extremities and mid point of the wire 12 are connected to members 17 which are connected by stiff conductors 18 to flat terminal members 19 provided with shoulders 19'. At the centre and extremities of the spiral groove are provided holes 15 which have a portion 15<1> recessed and are extended by slots 16 to enable the terminal members 19 to be passed through to the underside of the disc 10, the members 17 being retained in the holes 15 with their heads in the recesses 15<1>. Small rectangular apertures 25, Fig. 1, are provided in the disc 10 directly below the projections 13 in the groove 11. The disc 10 is mounted upon an insulating disc 20 within a metallic casing 22. The face of the lower disc is concave and is provided with an inclined groove 27 leading from its centre to a slot 26, so that any liquid which may fall upon the upper disc passes through the apertures 25 in the groove and is drained away. Slots 21 are also provided in the disc 20 to receive the terminal members 19. The unit may be held together by bolts passing through the discs and casing.