GB880027A - Improvements in or relating to controllers - Google Patents

Abstract

880,027. Thermal switches; fluid actuation of switches. FENWAL Inc. Aug. 15, 1958 [Aug. 19, 1957], No. 26253/58. Class 38 (5). [Also in Groups XIII and XXV] A controller has an input means responsive to a variable, e.g. temperature or pressure, an output means, e.g. a switch, a shiftable setting means, and a flexible non-extensible linkage means joining the input means with its output means and the setting means. As shown, a lever 49 pivoted at 50 is acted upon by the input means, which may be a bellows assembly 32 and is connected to one end of a metal band 68 which passes over a pulley 71 and is secured to a pulley 73 fixed to an adjusting shaft 60. The pulley 71 is carried by a lever 54 pivoted at 55 and a bracket 72a is arranged to actuate a snap switch 20 when a predetermined temperature or pressure is reached. The right-hand ends of levers 49, 54 are joined by a spring 59 to keep the band 68 taut. A pointer 74, secured to a pulley 75 fast on shaft 60 indicates the setting. The assembly 32 is adjustable lengthways of the lever 49, and contains an ambient temperature compensating bellows, the effect of which may be modified by incorporating one or more steel halls within it, Fig. 2 (not shown). A second switch may be operated after switch 20 by a bracket on a further lever parallel to lever 54, the bracket having a part bearing on the lower face of the pulley 71 Fig. 9 (not shown), or a second lever 54 and, band 68, together with a separate indicating pointer may be used, Fig. 10 (not shown). The second switch may be separately adjusted, Fig. 11 (not shown). The switch(es) are arranged in a separate compartment in a sealed casing 15. Specification 640,322 is referred to.