GB823535A - Improvements relating to two-stage hydraulic amplifier valves - Google Patents

Abstract

823,535. Fluid-pressure servomotor control systems. SANDERS ASSOCIATES Inc. Dec. 6, 1955, No. 34940/55. Class 135. A tar-stage hydraulic amplifier valve assembly has a first stage comprising a first valve closure member 3 movable with respect to fluid supply and exhaust ports 5, 8 in a housing 1 and a second valve closure member 2 movable with respect to at least one control port 9a in the first valve for controlling fluid flow through the control point to the second valve stage of the assembly, the first and second valve members being coupled by drive means 18, 20 carried thereby for moving the second valve member in response to a control signal, the second stage including feed-back means responsive to pressure variations produced in the second stage by said fluid flow for moving the first valve member with respect to the housing ports to cut-off said flow. Electrical input signals from e.g. a gyro compass, selsyn motor or potentiometer are applied to the terminals 22 to energize the two solenoids 18 carried by the sleeve valve 3 and displace an armature 20 against centralizing springs 21, 26 to move a control piston valve 2 allowing pressure fluid supplied from a port 5 or exhausted through a port 8 to act in a conduit 9 on the end of a piston valve 4. Movement of the valve 4 against a piston 16 hydraulically loaded from the port 5, laps the sleeve ports 7, 15 with the piston valve 2 through a follow-up lever 25. The valve 4 controls the supply and exhaust of fluid to a piston 14. The outside surface of the sleeve 3 may control supply and exhaust piston 14 in which case the parts 4, 16, 25 are dispensed with and feedback achieved by leading the pressure at 9a on to the end face of the sleeve 3 to counteract the fluid pressure force on the other face at 6. A potentiometer coupled to piston 14 may be used to cancel the input signal and restore valve 2 to its neutral position.