GB587427A - Improvements in or relating to fluid-pressure servomotors - Google Patents

Abstract

587,427. Fluid-pressure servomotorcontrol systems. STAUDE, E. G., and STAUDE, O. B. Nov. 22, 1944, No. 23230. Convention date, Dec. 8, 1943. [Class 135] A fluid-pressure servomotor comprises a pump 98, Fig. 3, normally circulating pressure liquid continuously through apertures in vanes 66, 67, which apertures can be closed by valves 74, 77 operable selectively to cause the pressure to build up behind a vane to move the latter. As applied to the actuation of an aircraft control surface, cables 1,2, Fig. 1, are connected to the pilot's control, and when moved to the left, for example, cause a lever 7 to swing anti-clockwise about its pivot 8 on a lever 10, the latter being connected through cables 14, 15 to the control surface. Besides swinging lever 7, the pull on cable 1 will also be transmitted directly throughpivot 8 to cable 14 and will cause the latter to start moving to the left. The lower end of lever 7 carries a tooth 31 engaging in a recess in a lever 33 keyed to a shaft 34 rotating in a sleeve 39 on which the lever 10 is keyed, and the anticlockwise movement of lever 7 will rotate lever 33 in a clockwise direction. The latter lever carries a see-saw lever 50 which will depress ball valve 77 to close the aperture in vane 67, and the pressure liquid from pump outlet passage 107 will build up behind the vane and move it in a clockwise direction. As the vanes are carried by sleeve 39, lever 10 will be rotated and will move cable 14 to the left. Movable vanes 66, 67 co-operate with fixed vanes 80, 81, and the liquid on the upper side of vane 67 will be forced through port 117, pipe 118, and port 119, through the aperture in vane 66 and out through port 87 and pipe 88 to the inlet passage 90 of the pump. The valves are re-centred by a spring-pressed lever 25 pivoted on lever 10 and engaging in a recess 28 in lever 7. The fluid pressure acting on the ball valves when the latter are closed will be transmitted to the pilot to give " feel." A relief valve 113 between the inlet and outlet passages of the pump permits the liquid to circulate freely when the lower supply fails and direct manual actuation of the control surface through lever 7 is required.