Patent GB-864904-A (GB)
Title: Improvements in aircraft jet propulsion engine controls
Inventor: CROWELL WALTER
IPC: F02K1/16
Filed: 1958-05-30
Abstract: 864,904. Fluid-pressure servomotor control systems. GENERAL ELECTRIC CO. May 30, 1958, No. 17450/58. Class 135. [Also in Groups XXVI and XXXV] A jet propulsion engine comprises variable compressor stator blades, a variable area jet propulsion nozzle and variable fuel supply, controlled in response to engine rotor speed and compressor inlet temperature. Three dimensional cams 49, 66, 79 are positioned axially by means of bellows 52 responsive to the compressor inlet temperature and angularly through a rack 54 and gear 53 by a governor 17 responsive to engine rotor speed, so that cam followers 48, 67, 81 take up positions which are functions of both compressor inlet temperature and the engine rotor speed. Cam 101 is movable axially only so that the position of its follower 102 is a function of compressor inlet temperature only. The follower 67 controls the pitch of the compressor stator blades through an hydraulic servomotor 71 and linkage 76. The main fuel control 11 comprises a metering valve 38 having a member 42 rotatable by bellows 45 in accordance with compressor discharge pressure, and an overlapping member 43 movable axially by means of a lever 57 which transmits the output of a differential 61. The output of the differential 61 is the difference between two inputs, one input being a manual setting transmitted by a lever 29 and gears 62 and the other input being a function of the engine rotor speed, transmitted from the governor 17 by gearing 63, 64. The upward movement of the member 43 is limited by the cam 49 and follower 48. The area of the jet propulsion nozzle is varied by means of an hydraulic servomotor 36, 96, the control rod 95 of which is actuated through levers 82-87 by the three-dimensional cam 79. The leverage can be varied by moving a fulcrum 88 lengthwise of lever 85 by means of a manually operated lever 28. Turbine discharge temperature is sensed by a thermometer 23, which applies a signal to a variable resistor 104 which is adjusted in accordance with the compressor inlet temperature by means of the cam 101 and follower 102, the output of the variable resistor being fed to an amplifier 105 as a reference signal. The signal developed by the thermometer 23 is also applied directly to the amplifier 105, which responds to the difference between this signal and the reference signal. A solenoid 106, energized by the amplifier 105, adjusts the lever 87 between stops 108 and 109. The reheat fuel control 14 includes cams 113, 114 movably axially in response to the compressor discharge pressure, to determine the inclination of a beam 118. The beam 118 controls a fuel metering valve 112 through linkage 128, 133. A throttling valve 111 maintains the pressure difference across the metering valve 112. The link 128 can be displaced transversely by a manually operable lever 27, to provide a reheat fuel flow between a minimum value determined by cam 114 and a maximum value determined by cam 113. The levers 27, 28, 29 are connected together to be moved in unison by means of the pilot's thrust selector lever.