Control mechanism for aircraft power plants comprising a gas turbine engine driving a propeller

摘要

861,601. Fluid-pressure servomotor-control systems. NAPIER & SON Ltd., D. July 25, 1958 [July 26, 1957], No. 23706/57. Class 135. [Also in Group XXVI] A control system for aircraft power plant comprising a gas turbine coupled to a propeller or helicopter rotor includes a swashplate fuel pump 13, the output of which is controlled in accordance with engine speed, and is passed through a metering valve 43 controlled by a servo mechanism 56, 57, also in accordance with engine speed, whereby the valve has a unique setting for each engine speed. Fuel pump 13 is of the type in which inclination of the swashplate is adjusted by a piston 18 working in a cylinder whose ends are interconnected through an orifice 23 and controlled by a leak-off valve 34 operated by a diaphragm 30 subjected through a port 25 in the pump casing 15 to a pressure proportional to engine speed, the diaphragm also being subjected to the loading of a spring 36, which can be varied by a pilotoperated lever 38 to vary the datum engine speed setting. The longitudinal position of sleeve 43, which is formed with a tapered port 44 furnishing the variable area fuel metering orifice, is adjusted by a power piston 57 controlled by a pilot valve 56 connected to an operating diaphragm 52 subjected to the pressures on the two sides of diaphragm 30. Piston 57 acts upon a valve loading spring 55, and is connected to sleeve 43 by a link 62. The latter is also connected by a link 82 to a lever 81 controlling a fuel dump valve 79, controlling the connection of the fuel supply line to a dump line 76 or the burner line 80. By operating lever 81 the pilot may open the fuel metering orifice to exceed its minimum setting, for engine starting. The pressure drop across metering valve 43 is communicated through pipes 70, 71 to the opposite sides of a diaphragm 73 controlling a bleed valve 75 connected to chamber 20 of the pump governor, to limit the pump output if the pressure drop exceeds a predetermined value;