GB1242967A - Temperature-compensated pressure transducer - Google Patents

Abstract

1,242,967. Fluid pressure actuation of switches. CAPVEST VENTURE CORP. 5 Aug., 1969, No. 39119/69. Heading H1N. A pressure-sensitive temperature-compensated switch assembly 10 includes a switch 21 in a closed volume 22 adapted to retain a reference pressure, the sensed pressure P acting on a flexible diaphragm 18 to actuate the switch 21, and a temperature compensating assembly 23 changing the reference volume with ambient temperature change to keep the reference pressure constant. Assembly 23 comprises two movable members of different effective working area such as the end sections 24a, 25a of bellows sections 24, 25, the ends 24a, 25a being coupled by a tie rod 27 to move as one when their common liquid-filled volume 28 expands or contracts with temperature rise or fall, the reference volume 22 thus being enlarged as a function of increasing temperature as bellows 24 contracts and bellows 25 expands. Analogous assemblies using a differential piston assembly, Fig. 2 (not shown), or two diaphragms, or a diaphragm and bellows assembly, Fig. 3 (not shown), are described. Volume adjusting screws 22b and 29b are provided for adjusting the reference volume 22 and a back-up volume 29 respectively. The volume 29 can be vented, and a spring 'inserted between the end 25a of bellows 25 and the base 12 of the housing 11 to provide biasing for the bellows 25. Switch 21 is a snap switch or an ordinary retractive switch.