GB326889A - Improvements in or relating to resistance units and electric heating apparatus comprising the same - Google Patents

Abstract

326,889. Young, Osmond, & Young, Ltd., and Turner, C. C. Dec. 27, 1928. Wire resistances.-A heating resistance of the type comprising a tubular frame consisting of a single tube 10 or a number of lengths of tubing connected end to end comprises one or more bars 14, 15 extending from end to end of the frame, on which are threaded mica plates 16, 20 with their planes transverse to the bars 14, 15 and spaced apart by short tubes 21. The coiled resistance wire 17 is threaded through eyeleted holes in the plates 16, 20, the ends being connected to the bars 14, 15 so that these form terminals. The plates 16 have parallel sides and curved ends to fit the enclosing metal or other tube 10 so as to space the bars 14, 15 therefrom, the plates 20 being smaller. The tube 10 is closed by end caps 11, 12 containing insulating blocks 13, 19. More than one resistance wire may be provided for multiple heat control, in which case each bar 14, 15 may constitute a return conductor, or the bars may be tubular and contain the return conductors, or the return conductors may be threaded through holes in the mica plates. The bars 14, 15 may be of circular, rectangular, polygonal, U., V-, L-shaped, or annular cross-section and may be arranged at the corners of a triangle or polygon, in which case the plates 16, 20 may be threaded over all the bars, or they may be straight pieces joining two bars which may be either adjacent or diametrically opposite. A single resistance element may be threaded in zigzag formation through apertures in the mica plates, or more than one resistance element may be carried by them. The plates may be secured to the bars by a pair of spring washers, one on each side, engaging grooves in the bars. The bars 14, 15 may be of insulating material, in which case the plates 16, 20 may be of metal, or both the bars and the plates may be of metal insulated from one another by bushings.