GB350640A - Improvements in electric heating elements - Google Patents

Abstract

350,640. Electric radiators. ROSS, F. A., 23, The Broadway, Tynemouth. April 9, 1930, No. 11232. [Class 39 (iii).] A heating unit comprises a resistance wire embedded in a refractory insulating material which is contained in a sheath which can be compressed without being extended ; further compression is applied by casting within an outer casing or sheath so as to provide a solid unit. As shown in Fig. 1, the resistance element a is embedded in magnesium oxide &c. b and enclosed in a split metal tube e, which is then reduced in diameter by making its sides overlap under pressure so as to compress the refractory material into a solid mass. An outer metal casing d having radiating fins f is then cast on, the casting being arranged to give maximum contraction around the central element. The metal sheath, instead of being in the form of a split tube, may consist of two channel or U-shaped metal sheaths fitting into one another. Fig. 4 shows such a construction in which the resistance element a is embedded in refractory material b within a channel-shaped sheath e, the two parts of which are compressed and the sides of the outer part bent over as shown. The unit is then cast with an outer metal casing d having concave ribs g, the inner surfaces of which are plated, vitreous enamelled, &c. so as to form a heat reflector. Ribs h are formed at the back of the casting and are covered by a sheet-metal back j so as to form a series of air passages in which air is heated by contact with the ribs, as described in Specification 317,929, [Class 39 (iii), Heating by electricity]. The sheet-metal back j may be polished to prevent radiation of heat to the wall &c. against which the heater is fixed. According to the Provisional Specification the metal sheath e may be omitted.