GB598670A - Improvements in and relating to hydraulic fluid control means - Google Patents

Abstract

598,670. Hydraulic apparatus ; fluidactuated valves. COMMERCIAL PATENTS, Ltd., and JOVES, G. F. April 13, 1945, No. 9307. [Classes 69 (ii) and 135] A control valve for a reversible hydraulic motor, and applicable, e.g., to the ship proplilsion installation described in Specification 598,654 and to the high-pressure hydraulic control means described in Specification 598,668, comprises a combined piston and lift valve member 3, displaceable in a cylinder 1 solely by hydraulic pressure, for determining the direction of live-fluid flow to the motor, and having a live-fluid inflow port 7, ports 10, 11 connecting with the motor and exhaust ports 8, 9, the arrangement being such that the valve member, during movement from one position to the other, byepasses live-fluid direct to the exhaust ports, thereby gradually reducing the speed of the motor in one direction and accelerating it in the reverse direction. The valve member 3 is actuated by pressure fluid admitted, under the control of a pilot valve (not shown), to either end of the cylinder through restrictions 13, this-pressure fluid being derived either from the same source as that supplied to the motor or from a separate source. When this pressure fluid is derived from the same source, pressure-maintaining means comprising a spring-loaded plunger 19, Fig. 2, in a casing 15, is included in the live-fluid supply to the port 7, Fig. 1, to maintain fluid-pressure upstream of the control valve when the latter is byepassing, thus ensuring that sufficient pressure is available to complete the actuation of the valve after this has been initiated. Pressure-fluid enters the pressure-maintaining means at a port 16 and after raising the plunger passes through a port 17 to the port 7. The connection between the ports 17, 7 may include a distributing valve adapted to byepass the live-fluid, or to direct it to the control valve, or to byepass some of the fluid and direct the rest to the control valve. The pressure-fluid inlet of the pilot valve is connected to the pressure-maintaining means at 18. A connection 23 is provided to take away any leakage past the plunger, such leakage being substantially prevented in the fully raised position of the plunger by engagement of the latter with a seat 20. When the valve member 3 is moved from the position shown to the right, a lift portion 6 of the valve member unseats and permits live fluid to byepass through the port 8, whilst continued movement places the port 9 also in communication with the live fluid until the lift portion 6 closes on its right-hand seat. Specifications 573,713 and 598,667 also are referred to.