Patent GB-241324-A (GB)
Title: Improvements in control means for valves
IPC: G05D16/10
Filed: 1924-08-06
Abstract: 241,324. Blakeborough, R. A., and Broadhead, J. B. Aug. 6, 1924. Valves controlled by pilot or relay valves.-An auxiliary valve device for controlling the operation of fluid actuated valves comprises a pair of interconnected double seated lift valves adapted to control the supply to and exhaust from the two ends of the main actuating cylinder or the cylinder actuating a relay valve. In the form shown in Fig. 1, each valve has a double faced head a<20> and a reduced part a<5> and is arranged to work in a ported liner d<2> so as to connect the actuating passage a<9> either with the supply pipe a<10> or the exhaust port a<4>. The valve spindles are interconnected by a lever c so that when one valve is supplying pressure to one end of the cylinder the other is simultaneously exhausting pressure from the other end of the cylinder. In a modification, the liners are dispensed with and the exhaust ports are arranged at the side of the casing. Fig. 4 shows the application of the invention to the actuation of a sluice valve d<1> adapted to close in the event of a break in the pipe line on the upstream side or an abnormal flow on the downstream side. The main valve is actuated by a piston working in a cylinder d<2> and is arranged at the, throat of a Venturi casing d. The supply pipe a<10> to the control valve is connected to the main conduit on the upstream side of the main valve through a valve d<13> and a leaky non- return stop valve d' while the exhaust pipes are coupled to the downstream side. The main control cylinder d<3> has one end connected to the inlet side of the main conduit by a pipe d<10> and valves d<9> and d' while the other side is connected to the throat of the Venturi through a cock d<6> and pipes d<4>, d<5>. In the event of an abnormal flow on the downstream side, the pressure at the throat falls and the inlet pressure raises the piston in the cylinder against the action of the weight d<14>. This throws over a tumbler weight d<17> which acts on the auxiliary valve lever to reverse the auxiliary valves and so close the main valve. A subsidiary control cylinder d<18> has a piston d<19> connected to the lever C and has the top end connected to the inlet through a pipe d<22> which is also connected to the valves d<9>, d<13> while the lower side is connected through pipe d<23>, d<12> and valve d<11> to a Pitot tube on the downstream side and through a pipe d<12>, valve d<9>, and pipe d<10> with the underside of the main control piston. In the event of a break on the upstream side the reverse flow causes the Pitot head to raise the piston d<19> forcing the water above the piston into the cylinder d<3> thus reversing the auxiliary valves and closing the main valve. Fig. 6 shows the application of the invention to a pressure reducing valve. In this form the main valve is actuated by a differential plunger e arranged to work in an inner casing arranged axially in the main casing e<2>. The auxiliary valves control the pressures in the annular space e<4> and in the inside of the plunger and are actuated by outlet pressure acting on a weighted plunger f. A modification of this form is described in which the main inlet and outlet connections are of the same diameter and the plunger f is loaded by a weight arranged on an extension of the lever c. By substituting a piston subject to both inlet and outlet pressures for the plunger f the valve may be adapted to close automatically in the event of an abnormal outflow. The inner casing may be carried by a detachable cover. A pressure regulating valve is also described in which the auxiliary valves control the pressures on opposite sides of a piston connected to a lift valve member movable at right angles to the pipe line. Fig., 7 shows the application of the invention to a selfclosing valve of the kind in which the main valve is controlled by a relay valve g adapted to coorerate with a seat in the main valve. In this application the auxiliary valves are actuated by outlet pressure acting on a piston g<12> and control the pressures on the opposite sides of a piston g<9> connected by rack and pinion gear g<4>, g<5>, g<7> with the spindle g<3> of the relay valve. Ports h, h<1> are provided communicating with the annular chamber e<4> and the inside of the plunger respectively so that a powerful hydraulic force may be applied in the event of the plunger sticking. This valve may be fitted with gear similar to that used on the form shown in Fig. 4 so that the valve will close automatically in the event of a return flow. By arranging the main valve to open instead of close when the outlet pressure falls it will act as a pressure regulating valve and by placing the piston g<12> under the control of the inlet pressure it will act as a pressure sustaining valve. Valves are provided so that the automatic gear can be put out of action and the main valve held in either the open or closed position. The auxiliary valves may be actuated by a float or an electric solenoid.