GB855541A - Fluid flow regulating valve - Google Patents

Abstract

855,541. Valves. UNITED HYDRAULICS Inc. Jan. 25, 1957 [Jan. 26, 1956], No. 2851/57. Class 135. A fluid flow regulating or metering valve actuated manually or by an electric motor, comprises a valve piston 50, Fig. 2, slidable in the bore 16 of a valve body 10 having annular channels 18, 20 separated by a land 61 and connected by passages 22, 24 to inlet and outlet ports 12, 14, either of which may be the inlet. The valve piston at one end is screw-threadedly connected to a valve operating stem 56 and at its other end provided with pins 64 which engage in slots 34 in the body to prevent rotation of the piston when the stem is rotated by a hand wheel 132 to axially move the piston. A portion 59, Fig. 4, of the piston has slight clearance between it and the land 61 to provide leakage flow and is formed with V slots 52 having a base portion which flares outwardly more rapidly in two directions than its pointed portion 54. To further accentuate a change in slot area along the portion 59 of the piston extra slots 63 may be interposed between the base portions of the slots 52. The piston 50 and the bore 16 need not necessarily be round nor the slots V- shape in cross-section providing three distinct ranges of metering are provided. In the position shown in Fig. 4 in which the full section of the piston co-operates with the land 61 the flow is described as viscous, is small and at high pressure. When the pointed tips of the slots 52 cooperate with the land 61 the flow is described as viscous-turbulent and increases with corresponding decrease in pressure. When the base portion of the slots 52 and the slots 63, if present, co-operate with the land 61 the flow is described as turbulent, the flow then increasing more rapidly. The valve operating stem 56 may be connected to the shaft of an electric motor which is provided with a screw-threaded portion engageable with a member which moves along the shaft but is prevented from rotating. This member carries electric contacts which engage other contacts on the motor casing to " make " and " break " switches to either stop or reverse the motor.