GB683819A - Improvements in electrical energy regulators - Google Patents

Abstract

683,819. Thermal switches. ASHE, T. S., and SUNVIC CONTROLS, Ltd. Dec. 15, 1950 [Dec. 29, 1949], No. 33264/49. Class 38 (v) An energy regulator of the character described in Specification 517,538 comprises an insulating base 1 carrying a snap-action switch 20, 25, 26, which may be of the trifurcated blade-spring kind such as described in Specification 585,972, two bimetal strips 7, 8 secured at adjacent ends to a pivotally-mounted bloc 6, an adjusting cam-follower lever 10 pivoted on an axis parallel with the pivotal axis of the bimetal strips and a bridge member supporting a rotary cam 9 and a shaft 15 with an adjusting knob 41. In Figs. 1 and 3, the axes referred to are perpendicular to the base and the bridge member comprises pillars 4, 5 on which the block 6 and lever 10 are pivoted and a metal strip 17 supported by the pillars. The cam 9 cooperates with a pin 14 on the lever 10 which has a tail portion 13 with an adjusting screw 18 engaging the free end of the bimetal strip 7. The strip 8 has an abutment 19 engaging the spring 20 of the switch. The strip 7 is heated by current flowing through it or by an encircling heater coil, whilst the strip 8 responds to the temperature of the surrounding air to compensate for variations in ambient temperature, the regulator controlling the energisation of a heating apparatus e.g. a hotplate, as described in Specification 517,538. The cam 9 has a slot 44 which the pin 14 enters to positively move the screw 18 away from the bimetal strip 7 when the adjusting knob 41 is turned to the "full-on" position. When the knob is turned to the "off" position the cam 9 maintains the switch contacts 25, 26 open. If "double-pole switching" is desired, one or more additional switches 32 ... 34 are provided, a further cam 36 opening the contacts 32, 33 when the knob is turned to the "off" position. In all the operative positions of the knob, the contacts 32, 33 are closed, the control being effected by the periodic opening and closing of the contacts 25, 26. In an alternative arrangement the pivotal axes of the strip 7, 8 and the lever 10 are arranged parallel with the base 1, the arrangement being shown in Fig. 6. In this case, a one-piece bridging member 52 carries the pivot spindles 50, 56, for the block 6 and lever 10 and the cam 9 is of the face-cam type.