GB714719A - Improvements in pneumatically operated control system - Google Patents

Abstract

714,719. Fluid-pressure servomotor-control systems. TAYLOR INSTRUMENT COS. Jan. 9, 1952 [Jan. 13, 1951], No. 709/52. Class 135 In a relay having an adjustable amplification factor for a pneumatically-operated control system, the pressure fluid controlling the relay is taken from a pressure-dividing network connecting the signal and output conduits leading, respectively, towards and from the relay, and the member in the relay responsive to the control pressure actuates a valve regulating a further, selectively adjustable, pressure supply which is then led away as the output fluid. The invention is shown applied to the system forming the subject of Specification 713,782 wherein the relay 40 is inserted after the 1:1 isolating stage B. A conduit 50, which includes two restrictions, e g. needle valves G1, G2, of which only one need be adjustable, interconnects the signal line 37A and the output line 49 from the relay, and the pressure controlling the relay is led off from between the restrictions and applied to a diaphragm 43. The latter is loaded by a spring 46 and is connected to a baffle plate 45 controlling the leak-off from a nozzle connected in line 49. A separate supply of pressure air is fed to line 49 past a restriction 48. The output from the relay is fed back past the derivative restrictor T to a capacity 29 and to chamber 18 of the first stage A, and the output from this stage will thus be amplified and include a component corresponding to the first time differential of the variable. The control pressure acting on diaphragm 43 is substantially a constant pressure so that, in a modification, this pressure is also applied to a diaphragm as a loading pressure in substitution of the spring 69 in unit D.