GB870834A - Fuel system for gas turbine powerplants with torque limiting mechanism - Google Patents

Abstract

870,834. Fluid-pressure servomotor control systems. UNITED AIRCRAFT CORPORATION. Nov. 4, 1958 [Nov. 15, 1957], No. 35341/58. Class 135. [Also in Group XXVI] A gas turbine engine comprising compressor, combustion and turbine sections 10, 12 and 14, Fig. 1, respectively, has the latter arranged in two parts the first of which 22 drives the compressor 10 whilst the second part or free turbine 26 is connected to an aircraft propeller or helicopter rotor 30. Control of the engine is effected by a fuel throttle 50 consisting of a cylindrical closure 52 reciprocable within a sleeve 54 incorporating a port 66, which sleeve is slidable in a bore 56 that communicates with fuel inlet and outlet conduits 58, 60, the closure 52 embodying inlet and outlet ports 62, 64; fuel flow into the. outlet conduit 60 is determined by the relative positions of ports 64, 66. The closure 52 is urged to the minimum flow position by a spring 68 between a flange 70 and the sleeve 54 whilst a pressure regulator, not shown, ensures a constant pressure differential between conduits 58, 60. The closure 52 is actuated by a spring-, loaded single-acting piston 74 via a pair of rollers 84 contained between the flange 70 and an inclined bar 86, the position of the piston 74 being determined by the position of a hinged closure 92 relative to a discharge orifice 90 leading from the cylinder 88 of piston 74 and to which fluid is supplied under constant pressure. The angle of the bar 86 is dependent upon the compressor discharge pressure whilst the movement of a throttle lever 34, Fig. 1, and compressor speed and inlet temperature signals are coordinated to determine the position of the hinged closure 92, Fig. 2. To limit the torque in the propeller or rotor drive another hinged closure 104 is provided which co-operates with an orifice 106 that communicates with the cylinder 78, the closure 104 being moved clockwise in response to ram pressure signals supplied to a corrugated diaphragm 114, and anticlockwise by speed signals from the free turbine 26 acting through a plunger 120; the closure 104 may also be moved anticlockwise by a hand lever 130 via a plunger 124 and a cam 128. The closure 104 is connected to the throttle valve closure 52 by a spring 134, bell crank lever 136, plunger 134 and a link 132 to provide "follow-up."