Patent GB-573894-A (GB)
Title: Improvements relating to apparatus for controlling hydraulic circuits
Filed: 1939-06-30
Abstract: 573,894. Valves. BRISTOL AEROPLANE CO., Ltd., PONTING, R., and MOORE, R. H. June 30, 1939, No. 19166. [Class 135] For controlling hydraulic circuits such as are used for the control of guns or gun-turrets on aircraft,. a reversing control valve is used in series with an additional valve mechanically interconnected therewith, the co-operating surfaces of the additional valve being so shaped as to permit of a gradual opening and closing of the circuit. As shown in Figs. 1 and 4, the main valve is a rotary valve comprising a barrel 33 mounted on an operating-spindle 15, and the lower end of the valve spindle is fitted with tappets 46 which are adapted to move the piston 50 of the additional valve to open up connection to the jack of the gun through a port 62 and connection 63, Fig. 4, the other end of the jack being connected to a connection 21 which opens into a groove 35 in the top of the barrel 33. The barrel 33 is formed with two sets of diametrically opposed slots 36, 37 leading from the groove 38, and 40, 41 leading from a lower groove 38 which has permanent connection with a space 59 in an adjustable sleeve 50, the outlet from the space 59 being controlled by a piston 64. The valve casing 10 is fitted with a liner 19 in which are formed grooves 25, 26 connected to unions 29, 32 joined to the pressure and inlet sides of a hydraulic pump. As shown in Fig. 4, the slots 36, 37, 40, 41 in the barrel 33 are separated by lands 42, 43, 44, 45 which normally prevent flow of liquid, but when the valve is rotated, fluid can flow from the grooves 25, 26 through the slots in a direction depending upon the direction of rotation of the shaft 15. The piston 64 is moved to the right simultaneously and as the front of the piston is tapered or formed with slits the flow of fluid is gradual at the start. The barrel 33 is drilled with a hole 72 to connect the grooves 35, 38 and so equalize the pressure in the valve. The sleeve 50 is adjustable by screw-and-nut mechanism operated by a hand wheel 53 formed with notches engaged by a spring 57 to hold it in position. In a modification, Fig. 8, the reversing valve is a piston valve 82 operated by links from a lever 95, and movable so as to connect together central ports 79 to either of the outer ports 78, 80, the valve being formed with lands 83, 84, separated by a space less than the distance between the outer ports 78, 80. The lever 95 also oscillates the auxiliary valve having the form of a rotary valve 100 with segments 103, 104 having circular parts of such a length as to close upper and lower connections leading to a unit 127 and to the ports 79. Adjacent the circular ports are chamfered edges 131, 132, 133, 134 which permit of a gradual opening of the valve. The through passages of the valve are equal to the maximum width of the passages 98, 99, and the valve can be adjusted axially by screw-and-nut mechanism so as to vary the operative size of the valve passage when the valve is fully open. This valve is also formed with an aperture in the piston 82 to equalize the fluid pressure. In other modifications, a rotary reversing valve may be combined with an additional rotary valve, or a piston valve with a piston valve.