GB1503155A - Solid plate electric heating units - Google Patents

Abstract

1503155 Resistance heating unit GENERAL ELECTRIC CO 29 April 1975 [10 May 1974] 17752/75 Heading H5H The resistance of a coiled strip-like resistive film 40 bonded to the underside of a solid plate 28 increases in steps from the central zone 72 of a hot zone to the outside of the hot zone, each turn of the coil being of uniform resistance/unit length so that the temperature distribution across the hot zone of the hot plate is substantially uniform. As shown, a resistive film 40 in the form of double spiral is bonded to the underside of a glass-ceramic plate 28. Each turn 74. 76, 78, 80. 82 of the spiral is uniform in thickness throughout its length, but the width of the turns decreases from the inner one 74 to the outer one 82. The resistance per unit length of the turns thus increases from the innermost turn 74 to the outermost turn 82. The film 40 is made of layers of gold and platinum, overlaid at its ends 86, 88 with silver to provide cold terminal connecting ends. A single point temperature control probe 90 is pressed against the film 40. A metal reflector dish 44 is provided. The arrangement described is part of a smooth topped hob provided with four hot zones. A metal plate 42 with four reflector dishes formed therein is joined to the glass-ceramic hob 28 by wrap around channel 48 and retained in the cooking range by a plurality of S-shaped springs 60. In Fig. 4 (not shown) a single spiral pattern, the width of whose turns decreases in steps from the centre outwardly is provided. In Fig. 5, the meandering circular formation provides turns 114, 116, 120, 124 whose width decreases from the centre turn 114, to the outer turn 124. The glassceramic plate 28 may be replaced by a metal plate insulated with porcelain enamel.