GB612309A - Improvements in or relating to apparatus for actuating the control surfaces of aircraft - Google Patents

Abstract

612,309. Electric control systems. BRISTOL AEROPLANE CO., Ltd., and DANIELS, L. C. M. March 16, 1945, No..6736. [Class 40 (i)] In an aircraft control surface actuating apparatus, the surface may be set automatically to either of its limit positions or to a predetermined position therebetween and switch means are provided, actuated by the control surface, as it passes through the predetermined position in one direction, to pre-set the apparatus so that when said predetermined position is subsequently selected the apparatus will move the surface in the opposite direction. As shown, the control surface 2 is positioned by hydraulic motor 4, supplied through pipes 10, 11 from selector valve 9 which is fed from locking valve 12. Pressure fluid is passed from valve 12 only when the apparatus is in operation, by the action of solenoid 13. Solenoids 15, 16 determine the action of valve 9 and hence the direction of motion of motor 4. Solenoids 13, 15, 16 are energized from battery 6 through push-buttons 1a, 1b, 1c, 3 and relays 5a, 5b, 5c. When the " up " button 1a is momentarily pressed the " up " relay 5a is operated and locks over contacts 7a and the locking circuit remains closed until the surface 2 reaches the " up position when the limit switch 8a is opened by a cam associated with surface 2. Over operated selector valve relay contacts 17 the " up " selector-valve solenoid 15 is energized to set the valve 9 to permit pressure-fluid to pass to the hydraulic motor 4 from the locking valve 12, which has been opened by the energization of solenoid 13 through the closure of contacts 14a. The flap 2 is thus driven to the " up " position. A similar sequence of operations takes place when the " down " button 1b is pressed. When normally closed, stopbutton 3 is pressed, the solenoids 13, 15, 16 are all de-energized and the locking-valve 12 is spring-urged to the closed position, thereby interrupting the supply of pressure fluid to motor 4 which stops. When flap 2 passes through the "take-off" position C during movement from a to b, the selector trip switch 20 is set to connect the normally open changeover relay contacts 19c in series with the selector-valve "up" solenoid 15. Similarly, as the flap passes through position C in moving from b to a, contacts 19c are connected in series with " down " solenoid 16. Thus, when the " take-off " button 1c is pressed, " takeoff " relay 5c is energized, locks over contacts 7c, locking valve relay contacts 14c and changeover switch contacts 19c are closed and the appropriate solenoid 15 or 16 energized, through the closed contacts 19a or 19b respectively. Fluid is passed to motor 4 to move the flap 2 to the " take-off " position, at which the limit switch operates and the holding circuit of a relay 5c is opened and the apparatus stopped. In alternative arrangements, the push-buttons may be placed in the holding circuits or may actuate all the corresponding relay switches.