GB497156A - Controlling aircraft engines - Google Patents

Abstract

497,156. Fluid-pressure servomotors. LUSTY, I. June 15, 1937, No. 16568. [Class 135] [Also in Group XXXIII] Aircraft propelling mechanism includes two or more engines each driving a variable-pitch airscrew, a plurality of datum-speed devices, one for each engine and each working at the same predetermined speed or frequency, means for adjusting the speed or frequency in unison and means sensitive to a change in speed of each engine relative to its datum-speed device for adjusting the pitch-control mechanism to correct the change in speed. As shown, a direct current electric motor 10 is mechanically coupled to a three-phase alternator 12 and its speed is adjustable through a rheostat 11. The alternator supplies three synchronous motors 13, 14, 15, each coupled through a clutch or coupling 19, 20, 21 to one of the aero-engines 16, 17, 18. The couplings 19, 20, 21 may be hydraulic and permit slip in the event of wide difference of speed between the engines 16, 17, 18 and the motors 13, 14, 15. Differential devices 28, 29, 30 each comprise a member driven by the aero-engine, a member driven by the appropriate motor 13, 14 or 15 and a member adapted to be moved to adjust the airscrew-pitch on the occurrence of a difference in speed between the first two elements. The devices 28, 29, 30 in one form comprise a valve sleeve 45 connected to the shaft 31 and a plug 46 connected to the shaft 32. The plug and sleeve co-operate with a stationary housing 51 having a fluid inlet-port 48 and groove 51 and ports 49, 50 connected to either end of a cylinder, a piston in which controls the airscrew-pitch. The sleeve and plug are provided with grooves or circumferential slits such that difference in speed between shafts 31, 32 causes relative rotation between the sleeve and plug to permit fluid under pressure to flow to the appropriate end of the cylinder controlling the airscrew-pitch. Drain grooves 60, 61 and orifices 69, 70 are provided.