GB281867A - Improvements in the control of hydraulic valves - Google Patents

Abstract

281,867. English Electric Co., Ltd., Deriaz, P., Thomas, W. D. J., and White, J. M. Dec. 3,1926. Stops, adjustable.-A. control gear for valves particularly applicable for use with valves used to admit liquid into a closed chamber of large volume for instance the chamber formed by the inlet pipe and spiral casing of a hydraulic turbine, is fitted with a stop device adapted to permit only a limited opening of the valve until the chamber is nearly or completely filled. The, pivoted stop 1 which co-operates with a rotating member 4 connected by a buffer springs 16 to a member 17 on a shaft 15 is under the dual control of a piston 10 acting through a rod 12 on an ann 13 and a cam 7 acting through a lever 9 and link 9<1>. The cam 7 is carried by a toothed wheel freely mounted on a shaft 6 and engaged by a toothed pinion on the shaft 15 and stops 20 are provided to limit the relative movement of the members 4, 17 and at the same time permit the stop to be pushed aside during the closing movement. In the closed position of the main valve the roller 8 rests on the raised part of the cam to the left of the notch so holding the stop 1 in its inoperative position as the main valve is opened the cam 7 is rotated in an anti-clockwise direction until the roller drops into the notch so placing the stop in the path of the member 4 to prevent further opening of the valve. When the pressure has built up in the receiving chamber it acts on the piston 10 to release the stop to permit further opening of the main valve. In the application shown in Fig. 3 the movement of the main valve is controlled by an auxiliary valve 21 working in a ported sleeve 22 and connected by a bell crank lever 26 to a control shaft 27. This shaft has a screw-threaded engagement with a non-rotatable nut 32 carried bv a member 34 connected to the main valves and is rotated by a worm wheel 28 slidably connected to it. The worm wheel engages a worm 29 on the shaft 15 which is adapted to be rotated by hand or by an electric motor acting through a. slipping clutch and toothed gearing. The control of the motor may be arranged so that at the end of the stroke of the servo motor in either direction the auxiliary valve is not brought back to its neutral so that the servo motor acts to hold the main valve in its adjusted position.