GB493652A - Apparatus for controlling the operation of devices operated by fluid pressure such as aircraft flaps - Google Patents

Abstract

493,652. Fluid-pressure servomotor-control systems. DUNLOP RUBBER CO., Ltd., BEHARRELL, G. E., WRIGHT, J., and TREVASKIS, H. June 19, 1937, No. 17136. [Class 135] [Also in Group XXXIII] Means for controlling a wing flap on an aircraft includes a pneumatic jack supplied with air under pressure through a central device incorporating a plurality of valves which are adapted to be selectively operated in predetermined sequence whereby the flap can be raised, lowered or moved to a mid-position and automatically locked in such position. As shown, three valves 18, 18, 31 are provided in a valve chest. A shaft 2 is journalled in the chest and provided with an operating lever 3. One or other of the valves 18 are operated, on rotation of the lever through a cam 7 which by means of spring-pressed sleeves 9 is frictionally-clutched to the shaft. The lever 3 may be locked in one of three positions, corresponding to flaps up, down or in a mid-position, by means of a spring-pressed roller 5 adapted to engage recesses 4. A cam 8 on the shaft 2 is adapted to operate the valve 31. The jack comprises a piston 38 movable in a cylinder 36 and carried by hollow piston rod 37 having an internal groove 41. A cylinder 42 is mounted at one end of the cylinder and a piston 45 is displaceable against the action of a spring 46. The piston is carried by a piston rod 44 having a reduced end portion 47 which normally engages balls 50 held in apertures in a sleeve 48. Movement of the lever from the up to the mid-position through the cam 7 depresses a plunger 12 to close by means of a washer 13 exhaust ports 53. The washer 13 is carried on a spindle 16 which through a spindle 17 opens the appropriate valve 18 against the action of a spring 18a to permit air under pressure to pass from a supply pipe 33 past the valve 18 to one side of the piston 38. The other side of the piston 38 is open to exhaust through the other valve 18. The movement of the lever through the cam 8 depresses a plunger 19, having an exhaust port 20 and carried by a flexible washer 21, to open the valve 31 against the action of a spring 32 to permit air under pressure to pass from the pipe 33 to the cylinder 42 to urge the piston 45 to the right. The piston 38 moves until the groove 41 is opposite the balls 50 at which time the piston rod 37 and consequently the flaps are locked in mid-position. Further movement of the lever 3 opens the cylinder 42 to exhaust and the piston 38 can move to the end of the cylinder.