GB1485412A - Fuel systems for gas turbine engines - Google Patents

Abstract

1485412 Gas turbine engine fuel systems ROLLS-ROYCE (1971) Ltd 27 Jan 1975 [15 Feb 1974] 7037/74 Heading F1G In a gas turbine engine fuel system comprising a variable displacement pump in duct means leading from a fuel reservoir to burners, further duct means for conveying fuel from the duct means downstream of the pump to an engine accessory, and means for preventing or permitting the passage of fuel to the accessory, the pump displacement is varied in accordance with a reference pressure in the duct means whereby the displacement is increased when the passage of fuel to the accessory causes the reference pressure to decrease below a predetermined level. Fuel is supplied to pilot burners 28 from a reservoir 10 via a backing pump 12 and a swash-plate pump 16. The pressure rise across the pump 16 is applied to a piston 58 in opposition to the action of a spring 66, the piston being connected via a lever 84 to the pump swash-plate which is normally in the position of minimum flow, any excess flow being spilled by a spill valve 44 which opens when the pump discharge pressure exceeds the required value. Demand for fuel as hydraulic fluid for operating the hydraulic rams 70 of the variable area jet nozzle 68 tends to cause a drop in pump discharge pressure, leading to a drop in any spill flow through the spill valve 44 and, at a predetermined value of the pressure rise across the pump 16, movement of the piston 58 to increase the pump flow, whereby change in pilot burner flow is minimized.