Patent GB-587159-A (GB)
Title: Control valve for fluid actuated devices
IPC: B64C25/22
Filed: 1944-04-05
Abstract: 587,159. Aircraft controls. DEHN, F. B. (Adel Precision Products Corporation). April 5, 1944, No. 6348. [Class 4] [Also in Group XXIX] A control valve especially for controlling the operation of hydraulic jacks or like actuators for the landing gear, flaps, brakes, cowl flaps, bomb doors, gun turrets, &c. on an aircraft is manually operable to supply the actuating pressure - fluid and is returned automatically to its neutral position on the completion of the stroke of the actuator by the consequent build-up of pressure. Referring to Fig. 1, the valve indicated at D controls the supply of pressure fluid from a reservoir A and pump B to the ends of a double - acting hydraulic motor C actuating one of the parts of the aircraft. A second similar valve E is also shown for actuating another motor F and inter-connected with valve D so that it is only possible to operate one valve at a time. The valve D comprises valve members 26, 10, 36, 11 and 27 actuated by a reciprocable cam member 41 having its ends formed as pistons and operating in a cylinder 24. Valves 10 and 11 control the supply of pressure fluid from passages 8, 9, which receive the fluid from a pipe 2 past a check valve 6, to passages 14, 14<1> and 15, 15<1> and pipes 18, 19 leading respectively to the two ends of the motor C. Valves 26 and 27 control the exhaust of fluid from the ends of the motor and are situated in the passages 14, 15 respectively, the exhausted fluid passing into the centre part of piston chamber 24 from where it is taken by a pipe 34 back to the fluid reservoir A. The valves are operated by cam portions 49, 47, 48 and 50 on the cam member 41 when it is displaced to the left or right from a central neutral position by a manually operable lever 57, Fig. 6, through a pinion 51 and rack 53, the pressure valve of one end of the motor opening with the exhaust valve of the other end. The valve 36 controls the pressure supply from pipe 2 to a pipe 40 leading to the second control valve device E and is actuated by a cam portion 46 so that only in the neutral position is it opened to allow the supply of pressure fluid to this other control valve. When the stroke of motor C is completed, the operating lever 57 may be brought back to neutral manually or automatically by the consequent build-up of pressure in either of the pipes 18, 19 and passages 14<1>, 15<1>, which. pressure opens a valve 65 or 64, which is spring loaded to keep closed against the normal operating pressure, and passes into the piston chamber-24 behind one piston end or the other of the cam member 41 to move it back to the neutral. central position. For this movement to be affected it is also necessary to relieve the pressure from the opposite end of cam member 41 and this is done by a pair of valves 71, 72 controlling the exhaust of fluid from the piston chambers through passages 73, 74 to the centre exhaust portion of chamber 24. These valves 71, 72 are both opened on initial movement of the lever 57 from its central and neutral position by a lost-motion and cam device 81, 82, 83, Figs. 6 and 9, which moves ring member 83 against a spring 88 to open the valves by pushrods 90, 91. One of these valves is allowed to close on releasing the lever 57 in its operating position by the centralising action of the cam device, but the other is maintained in the open position, to exhaust one end of the piston chamber 24 to allow the return movement of the cam member 41, by a segmental cam 92, Fig. 10, on the ring member 83 until the cam member 41 is returned to the neutral position. A positioning detent mechanism is provided for the lever 57 and cam member 41 comprising another cam member 94, Fig. 7, secured to theend of pinion shaft 54 and having three flats 95, 96, 97 co-operating with a leaf spring 98 for the two operating and one neutral position of the control valve. A pressure relief valve 99 is provided to guard against excessive pressures developing in the system due to heat.