GB458430A - Improvements in valve-operating mechanism - Google Patents

Abstract

458,430. Pump throttle - valves. GWYNNES PUMPS, Ltd., Hammersmith Works, Lincoln, and WAUCHOPE, G. A., 24, Gilpin Avenue, East Sheen, London. June 20, 1935, Nos. 17726/35 and 16985/36. [Class 102 (i)] [See also Group XXIX] A valve - actuating mechanism, particularly adapted for actuating valves in the discharge pipes of pumps comprises a piston connected to the valve which is moved to and normally maintained in one position by pressure fluid supplied by a power-driven pump which continues to operate while the piston is in the said position or is automatically brought into operation if the piston tends to depart from the said position and a controllable passage which permits the reverse transference of fluid when reverse movement of the piston is required. In the form shown in the Figure the actuating- piston is loaded by a weight 5 resting on a perforated support 6 and is directly connected to a sluice valve 2. The gear-pump 8 driven by a small electric motor is connected through a pipe 9 and conduit 10 with the chamber on the underside of the piston and through a pipe 11, non-return valve 12, and pipe 11<1> with an elongated port 13 on the wall of the cylinder 4. A byepass 21, 23, controlled by a manually operable valve 22 connects the pipes 9 and 11<1>, while a byepass 17, 21 provided with an adjustable throttle connects these pipes and is controlled by a valve 20 actuated by pressures derived from the inlet and outlet sides of the pump. When it is desired to open the main valve the valve 22 is closed and the pump started ; this withdraws liquid from above the piston and forces it below the piston, the pressure differential holding the valve 20 closed. When the lower edge of the piston uncovers the lower part of the elongated port 13, a return path for the liquid is opened and the movement of the piston is arrested. The pipe 11<1> is provided with valve controlled branches opening into the cylinder at points lower down the cylinder so that the valve may be held in partly open positions. As soon as the pump stops, slight leakage past the pump or slight backward movement permits pressure to build up in the pipe 11 which pressure acts through a pipe 14 to move a piston 16 and open the valve 20. This permits the transfer of oil and slow closing of the main valve at a rate regulated by the throttle 18. The main valve may be closed while the pump is still running by opening the valve 22 or an alternative valve connection 22<1>. In a modification the non-return valve is mounted on the outlet side of the pump and the valve 20 is actuated by a piston subject on one side to atmospheric pressure or main pump suction and on the other to main pump delivery pressure or high pressure elsewhere when the main pump is working. The loading weight may have a tappet adapted to actuate an electric switch to shut down the auxiliary pump motor when the valve is in the fully open position and restart it as it leaves that position. A modification is described in which an hydraulic intensifier replaces the rotary pump. With this form the liquid may be permitted to return through the high pressure side of the intensifier. In a further modification a centrifugal or turbine pump replaces the gear pump so that the controlled byepass 17, 21 and non-return valve may be dispensed with, the return flow taking place through the pump. When the main valve is used in the discharge pipe for a main electrically driven pump the controller or starter for the motor driving the auxiliary pump 8 may be interlocked with that of the main motor. Alternatively the auxiliary pump may be driven directly or through transmission gear from the main pump or its motor. According to the first Provisional Specification a readily reversible pump may be used which would revolve freely for reverse delivery when the main piston descends.