GB593741A - Improvements in or relating to electric immersion heaters - Google Patents

Abstract

593,741. Electric heating. COLLINS, G. H., and COLLINS, H. F. May 5, 1944, No. 8501. [Class 39 (iii)] An electrical heating element comprises an insulated resistance winding 23, in series with a thermostatically-operated switch, both being enclosed in a tube 35 of relatively small depth. The thermostatically operated switch comprises a plate 10 of channel cross-section having an aperture 15 through which a bi-metal switch 30, attached by rivets 33 to the bottom of the plate, can operate, and lugs 13 for clamping the contact carrying assemblies thereto. Flexible strips 16, 27 carry contacts 20, 28 respectively, and are attached to an insulating member 29 (which is also the former for the resistance winding 23) by means of metal strips 21, used in the manner of a lace, passing through apertures 24, and including in the case of flexible strip 16, a metal plate 17 having a bent over lug 19 through which the plate passes a screw 18 for adjusting the position of the said strip. Each metal strip 21 is bent at one end into a tubular form to receive the ends of the resistance element 23. The movement of the bimetal strip in response to an increasing temperature of the tube 35 with which it is in direct thermal contact, causes it to deflect member 27, through the intermediary of an insulating member 3, at a temperature determined by the adjustment of screw 18 to break the circuit by separating the two contacts 20, 28. Screw 18 is made accessible for adjustment after assembly through a hollow boss 37, which fits into an aperture 36 in the tube 35 and which is closed by means of the screw 39 and the cap 42 which can be soldered to the boss.