GB1463030A - Automatic fluid flow regulator - Google Patents

Abstract

1463030 Fluid-pressure servomotor systems POWERS REGULATOR CO 7 July 1975 28545/75 Heading G3P [Also in Division F2] A flow regulator for an air distribution system includes a plate 42 movable by the pressure differential thereacross against a spring bias 43 to vary the flow cross-sectional area of an aperture(s) 32 in a tubular housing 24, the logarithm of the crosssectional area of the aperture being inversely proportional to, and the spring bias varying non-linearly with respect to, the displacement of the plate. The bias is formed by three springs 46, 48, 50 each with different characteristics and the set point is adjusted by end-plate 54 which is mounted on the threaded end of a rod 38. The rod 38 is moved against a spring-bias 62 by a bellows 34 in an adjustable tubular guide (which also acts as an end step) according to ambient temperature. A thermostat 410, Fig. 9, sends a pressure signal Pc representing temperature to the bellows to adjust the rod 38 and thus the plate 42 to vary the flow according to temperature. The thermostat 410 has the upstream pressure P 1 fed to chamber 422 via restriction 420 and the downstream pressure P 2 fed to chamber 424. The two chambers are separated by a diaphragm 425 carrying a weight 426 and centrally apertured. The diaphragm moves away from a seat 427 to inter-connect the chambers according to the pressure differential thereacross and maintains a constant pressure Ps relative pressure P 2 . Ps is applied to a nozzle and flapper element 414 via restriction 434 so that as the flapper 440 moves to connect the chamber 436 to chamber 424 with the change in ambient temperature sensed by bellows 444 the signal pressure Pc is a function of temperature but referenced to P 2 so that the rod 38 is pressure balanced with respect to pressures P 1 , P 2 modifications of the flow regulator which do not require the referencing to pressure P 2 are described with reference to Figs. 4, 7 and 8 (not shown).