GB1482286A - Electric heater element - Google Patents

Abstract

1482286 Resistance heating element EMERSON ELECTRIC CO 16 July 1974 [12 Nov 1973] 31472/74 Heading H5H [Also in Division E2] To prevent sagging of a heating resistance coil 8 which is supported intermittently throughout its length, expansion of the coil 8 is prevented by spring clips 7 mounted on flat spaced insulators 10 provided with U-shaped notches 17 to seat turns of the coil, the spring clips 7 each engaging a turn of the coil 8 thereby limiting longitudinal expansion. Each insulator 10 is either in the form shown in Fig. 2 with two oppositely directed notches 17 to locate turns of two heater coils 8, or in a form with only one notch 17 (Fig. 3, not shown) to locate the turns of one heater coil 8. The insulators 10 are inserted in spaced holes 25 in channel section beams 5 and are retained therein by tabs 26 of the beams 5 engaging central openings 15 in the insulators 10. Pairs of grooves 18, 21 at opposite ends of insulators 10 co-operate with tabs 40 in the side walls 28, 29 of clips 7 to retain them in position. Each clip 7 is rectangular in plan having a discontinuous back wall 30 and a front wall 27. Front wall 27 has a vertical slot 32 extending from top edge 50 to an elongated aperture 33. Flanges 34, 35 are formed on either side of slot 32. The upper parts 36 and 38 of flanges 34, 35 respectively are twisted in opposite directions from the plane of wall 27 and the lower parts 37, 39 are twisted in opposite directions from the plane of wall 27, the upper and lower parts of each flange being twisted in opposite directions. This ensures that the width of the slot 32 at the top is bigger than the diameter of the wire of the coil and the width at bottom of the slot is smaller than the wire diameter. When a coil turn is introduced through slot 32 to the elongate aperture 39, the lower parts of flanges 34, 35 are forced apart by the wire to allow it to enter aperture 39. Once in the aperture 39, the wire is trapped between the upper edge of aperture 39 and the notch 17 in insulator 10 and its removal is prevented by the lower parts of flanges 34, 35 which return to their initial position. The metal clip 7 acts as a heat dissipating fin and in conjunction with its open ended insulator 10 scarcely shields the heating coil at all, thereby obviating local overheating. The beams 5 are supported between transverse support structures 3, 4 which are in turn secured to a front panel 2 carrying controls 9 which control the output of the stack of heater coils 8.