GB1163712A - Fuel Systems for Gas Turbine Engines. - Google Patents

Abstract

1,163,712. Gas turbine engine fuel systems. JOSEPH LUCAS ( INDUSTRIES) Ltd. Feb. 8, 1967 [Feb. 10, 1966], No.5845/66. Heading F1G. [Also in Division G3] A fuel system for a gas turbine engine comprises a pump 10, a throttle valve 18 through which fuel may flow to a main burner of the engine, means for controlling the output of the pump in accordance with the opening of the throttle valve, a shut-off valve 25 disposed downstream of the throttle valve which may be actuated to prevent fuel flow to the main burner, and means for supplying fuel to a starter burner. A subsidiary supply passage 52 is provided for connection to the starter burner, the subsidiary passage communicating with the main supply passage 21 leading to the main burner, and the shut-off valve 24 is disposed in the main supply passage at a point downstream of the connection with the subsidiary passage 52. A control valve 57 is disposed in the subsidiary supply passage so that a proportion only of the fuel supplied thereto can reach the starter burner, the control valve being actuable in conjunction with the shut-off valve 24 such that as the shut-off valve is opened to permit fuel flow to the main burner the supply to the starter burner is reduced. The fuel system shown comprises a swash-plate type pump 10 which receives fuel from a backing pump 14 and delivers through line 16 to a unit 17 which comprises a passage 21 controlled by a throttle valve 18 the position of which is selected by a pilot's lever 19. Fuel may discharge from passage 21 through a pressurizing valve 22 to a line 23 leading to a main burner, a fuel shut-off valve 24 operable by a lever 25 being disposed in the passage 21. A passage 52 communicates with the passage 21 at a point upstream of the pressurizing valve 22 and shut-off valve 24, the passage 52 communicating through a control valve 57 with two lines 53, 54 having restrictions 55, 56, the line 53 leading to a starting burner and the line 54 leading to the backing pump. The control valve 57 is mechanically linked with the shut-off valve 24 so that as the one is opened so the other is closed and vice versa. The output of the swashplate pump 10 is controlled by the servo-device 12 by the pressure difference across the throttle valve 18. Pressure upstream of the throttle valve is communicated through line 30 to the upper side of diaphragm 29 while pressure downstream of the throttle valve is communicated through line 31 to the lower side of the diaphragm. The diaphragm acts through member 33 on a lever 34 to control leak-off through line 37 and thus the position of servo-piston 12 and so the angle of the swash-plate 11. The opposite end of the lever 34 is carried by a stem connected between two capsules 42, 43, the capsule 42 being subject to pressure in line 38, 39 between restrictions 40, 41, the line 38 being connected to air intake pressure, and the capsule 43 being evacuated. The pressure drop across the throttle valve 18 is modified in accordance with temperature conditions by means of the device 44 which acts to vary the pressure downstream of the throttle. A by-pass 26 is provided across the throttle 18 and a further by-pass is provided across the throttle 18 and the pressurizing valve 22.