GB740631A - Improvements relating to valves for regulating fluid flow - Google Patents

Abstract

740,631. Fluid-actuated valves. PRENDERGAST, C. S., and GORDON, H. Dec. 16, 1953 [Feb. 16, 1953], No. 4264/1953. Class 135. A valve for controlling the spill of surplus fluid from a liquid system has a controlled pressure chamber X with an inlet 1B from the system and a spill outlet 3C; the effective area of which can be adjusted by a manually settable member 6, the controlled pressure chamber being bounded by two interconnected pistons 2, 4 of different diameters and the smaller piston 2 operating to shut off the inlet in opposition, to a spring 12 acting on the larger piston 4. The inlet is formed as a transverse bore 1B extending diametrically through a bore 1A for the piston 2 in a body part 1 and being connected at its ends to the system. The member 6 consists of a throttle adjusted by a screwed spindle 6A. The larger piston 4 which operates in a bore 3A in a body part 3 has a bifurcated extension 4A connected by a cross pin 5 to the rod of the smaller piston 2. A perforated baffle 13 is arranged at the junction of the bores 1A, 3A to prevent pressure fluctuations due to high-velocity flow into the controlled pressure chamber. The body parts 1, 3 are closed by end caps 10, 11 with recesses 10A, 11A connecting the bores 1A, 3A by ducts 1D, 3D with the spill outlet 3C. The arrangement shown ensures a constant spill from the pressure system for given position of the throttle 6 irrespective of the pressure in the system. In a modification however the smaller diameter piston has a stepped part against which the pressure in the system acts so as partly to offset the effect of the loading spring. In this case the rate of spill decreases as the pressure in the system increases so that hydraulic slip in other parts of system may be compensated.