GB825048A - Automatic hydraulic regulating apparatus - Google Patents

Abstract

825,048. Fluid-pressure servomotor-control systems. CURTISS-WRIGHT CORPORATION. Nov. 1, 1955, No. 31242/55. Class 135. An hydraulic regulating apparatus comprises a reversible hydraulic actuator, such as the power piston 54, movable in opposite directions under the control of a pilot valve 16 movable automatically to either side of a neutral position and directly connected with a movable wall 71 so as to,expand or contract a fluid pressure chamber 72 upon movement of the pilot valve in opposite directions, the chamber 72 being in free fluid communication with a compensating chamber 99 having a movable wall, such as the piston 96, held in a neutral position by resilient means acted on by the hydraulic actuator to vary the neutral position. The apparatus enables the degree and rate of response of the actuator to movements of the pilot valve to be adjusted. In the case of a speed governor the pilot valve 16 rotates with and is axially slidable within a sleeve 15 under the control of flyweights 20 movable outwardly against the action of an adjustable tension-spring 30. The sleeve 15 is rotated by an engine-driven or other shaft 10, the speed of which is to be maintained constant. The shaft 10 through gears 37, 38 drives a pump 35 supplying fluid through a pipe 40 to the pilot valve 16. The latter has valve heads 17, 18 controlling outlet ports 49, 50 leading to opposite sides of the piston 54. The sleeve 15 also has inlet ports 42 and exhaust ports 60, 61. The chambers 72, 99 are connected by a passage 85 which is also open to a sump in an outer casing 32 through an adjustable needle valve 90. The resilient means acting on the piston 96 comprise opposed springs 97, 98. The upper spring 97 acts also on a piston 100 having a vent port 110 and connected by a link 101 to a slotted arm 105 rigid with a control-shaft 11 connected to the power piston 54. The pivot 106 of the link 101 is adjustable in the slot 104 to vary the degree of movement of the piston 100 for a given movement of the power piston 54. The shaft 11 is connected to the engine throttle valve or other fuel control means by an arm 12. The springs 97, 98 may be replaced by a single spring which is neither in tension or compression in the neutral position. The piston 96 may be replaced by a diaphragm or an expansible chamber member.