GB642264A - Improvements in or relating to electric heating units - Google Patents

Abstract

642,264. Electric hot-plates. WIEGAND CO., E. L. Feb. 10, 1948, Nos. 3861 and 3862. Convention dates, Dec. 5, 1940, and Aug. 23, 1941. [Class 39(iii)] An electric heating element rests freely and slides on the upper edges of a metal web 27 and has tongues 39 bent to engage transverse elongated slots 37 in the arms of the web so that the element on expansion is free to slide in the plane of the web surface but cannot move away therefrom. The elements of a hot-plate comprise wire resistances embedded in refractory material in metal tubes of triangular cross section, and two such spiral elements 10, 11 are mounted with flat surfaces uppermost in one plane on a metal web comprising arms 27 mounted on a central metal disc 63. The outer ends 52 of the arms engage in slots in a circular downward flange 49 of a metal ring 50 with an outer rim 51 resting on the edge of a recess in a range top. The elements are of different resistances and may be connected together or separately to a supply of two different voltages. The ends of the elements are bent down and then slightly up from a drip point 25 to enter a terminal box 18. The element 10 has two turns spiralled on itself about the disc 63 and an outer turn; the element 11 has two turns, one turn being intercalated with the outer part of the element 10. A reflector 24 has a slot 58 through which passes a hook 54 depending from a support arm 27 and has a downwardly pressed trough 59 with adjacent pressed up recesses 61 resting on ledges 44 on a bracket 42 engaging the ring 49 and threaded on to the end parts of the heater elements. An air gap extends peripherally between the lower edge of the vertical 49 and the reflector, which is removable laterally. The surface of the flat top of each tubular element is greater than each of the lower side surfaces, the element being pressed in dies to a triangular cross section as described in Specification 654,765.