GB957900A - Improvements relating to pneumatic control systems - Google Patents

Abstract

957,900. Valves. FAIREY ENGINEERING Ltd. June 18, 1962 [June 22, 1961], No. 22708/61. Heading F2V. [Also in Divisions B7, F1 and G3] A pneumatic control system for actuating a control surface or control pressure jet of a rocket propelled guided missile comprises a double acting pneumatic jack 10 having both of its ends adapted to be permanently connected through branch conduits 25A, 25B having throttling restrictions 26A, 26B with a supply of hot compressed gas, each branch conduit having a relief port 21A, 21B communicating with a low-pressure region, and selector valve means 36 having two operative positions and an intermediate position, the valve means in either of its two operative positions fully closing and sealing one relief port and fully opening the other relief port. The relief ports open to the atmosphere in a concave surface 31 of a member 30 secured to a frame supporting the jack. The valve means consists of a member 36 which has a convex surface 37 and is secured to an armature 33 movable from an intermediate position, wherein each port is partly covered, to one or other of the operative positions by selective energization of electromagnets 41, 42 having U-shaped cores on opposite sides of the armature, the coils being energized by signals from the gyroscopic controls of the missile or from a ground control station. When a coil is energized to move the member 36, the complete opening of one relief port causes a drop in the pressure in the chamber of the jack associated with that port and the closing and sealing of the other port causes a rise in pressure in its associated chamber to effect movement of the piston of the jack. In the intermediate position, the cylinder is filled with stagnant gas and when the selector valve is operated to effect movement of the piston, the opening of a relief port permits the hot gases to escape without passing through the cylinder. The double-acting jack may comprise two cylinders having a common piston or their two pistons coupled together and the selector valve may be of the slide or plunger type.