Patent GB-854888-A (GB)
Title: Hydraulic control system for controlling a remotely positioned valve
IPC: G05D9/04
Filed: 1958-01-23
Abstract: 854,888. Fluid-pressure servomotor control systems. JAROCO ENGINEERING CO. Jan. 23, 1958 [Nov. 13, 1957], No. 2365/58. Class 135. In an hydraulic servomotor control system for actuating a remotely disposed valve controlling the filling of a tank with liquid, including an hydraulic motor actuating the valve and a control valve therefor, a float suspended in the tank at the desired liquid level on the liquid reaching that level disengages a clutch to release trigger means to actuate the control valve so that the remotely disposed valve automatically closes. As shown, a valve 18, Fig. 1, in a line 14 supplying the tank includes a valve member 24 mounted on a stem 26 which is raised and lowered by bevel gearing 28, 30 driven by a reversible rotatable hydraulic motor 32 controlled by a remotely disposed control valve 42. The valve 42 comprises a three-landed valve spool 48 which when moved from its neutral position shown, controls the flow of pressure liquid from an hydraulic accumulator 66 through one or other of lines 34, 36 to the motor and exhausts it through the other of the lines 34, 36 to a reservoir 80. A manually operable lever 84 connected to the spool at 85 is connected at its lower end by a rod 90 to a telemotor link comprising a spring- loaded piston 88, bellows 96 and a line 100 connecting the bellows with a similar bellows in a housing 31 into which the valve stem 26 projects. The spool is formed with a shaft 136 between which and a shaft 138 carrying a piston 142 is located a trigger lever 113 depending from a sleeve 114, Fig. 3, loosely mounted on a shaft 110. The sleeve is formed with teeth 117 engageable with corresponding teeth 115 on a clutch 112 splined to the shaft 110. The sleeve and clutch being urged apart by a spring 119. The shaft 110 at one end carries a sprocket 102 over which passes a chain 104 supporting a float 106 within the tank and a counterbalance weight 108 and at its other end is coupled through reduction gearing 120 to a shaft 124 carrying an indicator needle 132 which cooperates with a fixed dial 126 to indicate the amount of liquid in the tank. Between the piston 142 and a piston 144 locked in position by a latch lever 156 is compressed a spring 146. The latch lever 156 is held in a recess 154 by a spring-loaded piston 160, Fig. 5. A crank 122 fixed on the shaft 110 is first turned to raise the float to the level at which it is desired to fill the tank, the level being indicated on the dial 126. The sleeve and clutch are then pressed into engagement with each other and on release of the crank torque caused by the weight of the float retains the teeth 115, 117 in engagement against the spring 119. The torque also acts on the trigger lever 113 to urge the piston 142 rightwardly to compress the spring 146. The lever 84 is then moved to " open " position whence pressure liquid is directed to the motor 32 through the line 34 to open the valve 18. The raising of the valve stem 26 forces liquid into the bellows 96 to move the rod 90 leftwardly and rotate the lever 84 about pivot point 85 until the valve 18 reaches its fully open position, whence any additional leftward movement of the rod 90 moves the spool to close the inlet 60 and on release of the lever 84 adjusts the spool to its neutral position. On the liquid level in the tank reaching the float 106, the support given to the float reduces the torsional engagement between the teeth 115, 117 in the clutch 112 and sleeve 114 respectively so that the spring 119 disengages the clutch and the spring 146 through the piston 142 and shafts 136, 138 moves the spool 48 to direct pressure liquid through the line 36 to the motor 32 to close the valve 18. On the valve reaching its fully closed position pressure in the line 36 builds up to open a valve 176 to direct pressure liquid to act on the piston 160 against its spring to release the latch lever 156 to release the pressure acting on the spring 146 and shafts 136, 138 and allow the spool 48 to return to its neutral position. The latch lever 156 is reset by a locking handle 152. Specification 809,517 is referred to.