Patent GB-694314-A (GB)
Title: Improvements in or relating to hydraulic remote control systems
IPC: F15B11/10
Filed: 1950-04-27
Abstract: 694,314. Hydraulic machines: fluid-pressure servomotor-control systems. STEWART. W. A. April 26, 1951 [April 27, 1950], No. 10403/50. Classes 69(ii) and 135 A hydraulic remote control system for controlling an engine throttle and the positioning of a clutch in the engine output shaft comprises a hydraulic resistance 5, Fig. 1, having its inlet connected to a supply pump 2 and its outlet to a singleacting servomotor 9 whose piston 10 is operatively connected to the engine throttle, and a combined control and selector valve 15 operable by a handle 19 and positioned in a branch line between the resistance and the servomotor to control the throttle and select the clutch position, the arrangement being such that with the clutch in neutral position the engine idles and with the clutch in either its ahead or astern position the engine throttle opening may be varied so that with increasing engine speed the throttle lags behind handle movement and with decreasing engine speed this lag is eliminated. As applied to a marine Diesel engine, the resistance is constituted by an adjustable needle valve 53, Fig. 3, whose inlet 45 is connected to the supply pump through an inlet connection 32, passage 35, filter 36 and a spring-loaded plunger 43, on rotation of the plug 39 of a combined control and selector valve from its neutral position, to connect one or other of radial ports 63, 64, Fig. 5, with the inlet. The resistance outlet is connected to the servomotor cylinder by a passage 70 and a connection 30, Fig. 4, and to sump by a passage 56, a recess 58 in the plug 39 having V-shaped end grooves 59, 60 and a casing port 62. To operate the clutches, the plug is formed with a radial port 65, Fig. 6, for connection with one or other of passages 66, 67 communicating with the astern and ahead clutches respectively. The plug 39 is rotatable by a lever 22 connected through linkage and a telemotor system to a control lever on the ship's bridge. On rotation of the plug 39 to connect, e.g. the port 65 with the passage 67 and the port 63 with the inlet 45, and with the recess 58 still in communication with the passage 56, the ahead clutch is operative and pressure liquid overcoming the spring-loaded plunger 43 is supplied to the needle valve 53 and after passing therethrough is delivered to the servomotor cylinder and sump. Since the recess 58 offers little resistance to the flow to sump the pressure in the servomotor is insufficient to move its piston against its spring and the engine runs at idling speed. On further rotation of the plug 39 in the same direction, the grove 59 is engaged and the outflow to sump progressively throttled to slowly increase pressure in the servomotor to move its piston and hence operate the engine throttle to increase engine speed which takes place with some delay. On rotation of the plug so that the recess 58 again communicates with the passage 56, the pressure in the servomotor rapidly decreases and the spring immediately moves its piston to move the engine throttle to idling position. Should the filter become choked, unfiltered pressure liquid may pass to the resistance through a spring-loaded check valve 68. the ports in the plug may be arranged so that the throttle responds prior to the engagement of the clutches. According to the Provisional Specification for the operation of a ship's rudder the servomotor may be double-acting and two hydraulic resistances employed, one associated with each end of the servomotor cylinder. In this arrangement, a common leak-off control valve may be used or separate valves increasing the pressure on one side of the piston whilst decreasing it on the other.