Patent GB-890631-A (GB)
Title: Improvements in fluid powered actuator
Inventor: KRAUSS HANS GEORGE
IPC: B64C13/00
Filed: 1960-01-22
Abstract: 890,631. Fluid-pressure servomotor-control systems. BOEING AIRPLANE CO. Jan. 22, 1960, No. 2373/60. Class 135. Construction.-An aircraft control surface 24, Fig. 1B, is actuated by fluid-pressure supplied to a double-acting piston 11 under the direction of a valve 14 attached to the cylinder 28 of another double-acting piston 31, Fig. 1A, the cylinder 28 being also connected with lostmotion through lugs 26 to the rod 13 of the piston 11; the rod 32 of piston 31 is connected to the pilot's lever 34. Attached to the cylinder 28 is housing 35 containing control-valves 36, 37, and a selector valve 38 whilst the rod 32, normally connected thereto, may be uncoupled therefrom by a fluid-pressure lock 88. The valve 37 comprises an axially movable sleeve 39 with supply ports 40, 44, an exhaust port 42 and outlet ports 41, 43, which valve is joined by linkage 45-48 to the rod 32 to provide a feed-back ; slidable in the sleeve 39 is a spring- centred piston-valve 49 having grooves 52-54 and a central bore 55 which communicates with both end chambers 56, 60 through a restriction 57 and a metering pin 59, respectively, and with the exhaust port 42 by a transverse passage 58; the chambers 56, 60 are supplied with fluid from ports 40, 44 via restriction 61, 62, respectively. The metering pin 59 is actuated by a gyroscope 98 responsive to rate of turn. The valve 36 consists of a four-landed piston having one supply port 69, two exhaust ports 70, 71 and two outlet ports 74, 75, the valve being operated by an automatic pilot producing electrical signals indicative of the departure and/or rate of departure of the aircraft from a desired attitude, which signals are fed to a torque motor 95; a potentiometer 96 on the rod 32 provides a feed-back. The selector valve 38 is a three-landed pistonvalve movable by a manually controlled solenoid 81, the valve being connected to the outlet ports 41, 43, 74, 75 and through passages 82, 83 to opposite sides of the piston 31. Operation.-With the valves 99, 100, Fig. 1B, in the fluid supply line 102 in the position shown, and the solenoid 81, Fig. 1A, de-energized, the valve 36 is ineffective whereupon any movement of the metering pin 59 produces a pressure unbalance between chambers 56, 60 and hence motion of the spool 49 to connect opposite sides of the piston 31 to supply and exhaust and cause translation of the cylinder 28 to actuate valve 14, Fig. 1B, to bring about movement of the piston 11. The linkage 45, 48, Fig. 1A, acts to re-position the sleeve 39 and restore the previous relationship between the latter and the spool 49 and so halt the cylinder 28. Upon energizing solenoid 81 the valve 38 is positioned to render the valve 37 ineffective and put the valve 14 under the control of the automatic pilot with its potentiometer feed-back 96. Any movement of the lever 34 is transmitted through the rod 32 and the fluid on either side of the piston 31 to the valve 14 independently of the control afforded by the gyroscope 98 or the automatic pilot. If for any reason the pilot desires to control the aircraft without the aid of the automatic pilot or gyroscope the valve 100 is moved to its other end position to exhaust the system whereupon the lock 88 is actuated to couple the rod 32 and housing 35 and centre the piston 31, movement of which is permitted by opening of a valve 92 between the passages 82, 83; a direct mechanical connection is thereby established between the rod 32 via housing 35, cylinder 28 to the valve 14. Upon closing the valve 99 to shut-off the supply of fluid to the entire system a valve 21 interconnects the two sides of the piston 11, and the surface 24 may be operated directly through rod 32, housing 25, cylinder 28, lugs 26 and rod 13.