GB1260674A - Improvements in or relating to temperature controllers - Google Patents

Abstract

1,260,674. Temperature responsive actuating elements. FUNDITOR Ltd. April 23, 1969 [April 26, 1968], No.19936/68. Heading G1D. A temperature controller comprises a spring- loaded piston 19 adapted to be moved along a cylinder bore by the thermal expansion of a fluid in a tube 38 and a bulb 40, a sleeve 20 secured to the piston and a seal 22 between the piston and the cylinder bore, the sleeve having a portion of reduced diameter so that during the stroke of the piston the working surfaces of the seal and the sleeve do not slide over any common portion of the cylinder bore working surface. The bore is formed by a sleeve 17 cemented in a body 3 and the spring-loading is provided by a spring 28 which engages the flange 27 of an operating plunger 26. The sleeve 20 is made of nylon whilst the sleeve 17, the piston 19 and the body 3 are made of mild steel, and the seal 22 is made of neoprene. The expansible fluid may be mercury and the element 1 is mounted in a housing 34. Expansion of the fluid in the bulb 40 causes the plunger 26 to rotate a beam 42 about its pivot 37 thus causing a link 43 to extend a spring 461 and a rack 48, connected to the beam by plates 45 and a pin 52, to move upwardly. The rack is biased into engagement with a pinion 50 by a spring 49. A pointer 58 is secured to the pinion 50 so that movement of the rack rotates the pinion thereby moving the pointer 58 over a scale 60 marked in degrees. A second pointer, the position of which on the scale may be pre-selected and an arm carrying a micro-switch are adjusted by an external knob to a position corresponding to the pre-selected temperature. When the pointer 58 reaches this temperature a rod 68 operates the micro-switch to switch off a heating current thus allowing the material in which the bulb 40 is immersed to cool.