GB887775A - Fuel control mechanism - Google Patents

Abstract

887,775. Variable pitch propellers. UNITED AIRCRAFT CORPORATION. July 6, 1959 [July 7, 1958], No. 23181/59. Class 114. [Also in Groups XXVI, XXXVIII and XL(b)] In a system for controlling the thrust of an engine in accordance with its temperature and speed, the control is effected primarily in accordance with temperature at high powers, and primarily in accordance with speed at low powers, additional means being provided to limit the control when accelerating or decelerating to prevent the temperature from becoming too high or two low. As shown, Fig. 1, a gas turbine engine 28 is fed with fuel by a pump 40 from an inlet pipe 42 through a throttle valve 46. A valve 50, responsive to the pressure on opposite sides of valve 46, controls a bypass round the pump 40 to maintain a constant pressure drop across valve 46, which is positioned by a bellows 54, and a valve 52 controls the pressure inside the bellows to overcome an internal spring (not shown) normally closing the valve 46. Valve 52 is controlled by a solenoid 60. The engine speed is measured by a tachogenerator 30, and compared with the engine temperature measured by thermocouples 38, the relationship being adjusted by a lever 82 to give the required operating characteristics at different positions of the lever, by controlling solenoid 60 with the comparison signal. Apparatus 104, 160 provide over-riding signals to prevent the engine temperature from becoming too high or too low. The system is applicable to engines with variable area exhaust nozzles, control being effected via a motor actuating eyelids for the exhaust nozzle, and to propellor turbine engines, by controlling the exhaust nozzle area or the pitch of propeller 208, Fig. 10, by the variation of pressure in pipe 220, the speed of the engine automatically adjusting itself to give the selected engine temperature. Specification 656,208 is referred to.