GB234194A - Improvements in the method of and apparatus for automatic control - Google Patents

Abstract

234,194. British Arca Regulators, Ltd., and Lindsay, T. Feb. 28, 1924. Valves controlled by pilot or relay valves.-A controlling device particularly applicable for controlling the flow of a fluid, an electric current, the speed of machinery, humidity or temperature and of the type in which variations of the pressure of a non- compressible fluid continuously passing through a discharge aperture are used for controlling the. operation of the device, is provided with means for producing and transmitting by said non-compressible fluid a compensating impulse adapted instantaneously to check the tendency of the apparatus to over or under-regulate. The Figure shows the application of the invention to the control of pressure in a steam pipe. The main valve 3 is opened against the action of a counterweight 10 by fluid pressure acting on a piston. Pressure is admitted to or exhausted from the cylinder through pipes 13, 19 under the control of a double-seated valve 14 itself actuated bv a spring-loaded diaphragm &c. Pressure fluid is admitted to the diaphragm chamber through a. pipe 20 and needle valve 18, and is exhausted through a pipe 20 and discharge orifice 23. The rate of discharge from the orifice 23 is controlled by a cup 31 mounted on a lever 37 with knifeedge pivots 37 and actuated by steam pipe pressure acting on a bellows 34 against the action of a spring 38. The lever 37 is elastically connected to a second spring-loaded lever 40 actuated by a bellows 43 subject to the pressure in an air vessel 48. The lower part of the air vessel is connected by a conduit 46 controlled by a needle valve 47 to the power cylinder so that when the pressure is increased or decreased in the power cylinder a corresponding impulse is transmitted to the bellows 43 tending to restore the cup 31 to its original position.