GB887780A - Improvements in or relating to fuel control systems for internal combustion engines - Google Patents

Abstract

887,780. Gas-turbine plant. PLESSEY CO. Ltd. Nov. 14, 1960 [Nov. 26, 1959], No. 40216/59. Class 110 (3). A fuel control arrangement in a gas-turbine fuel system having a fixed displacement pump driven by the engine which, acting alone, would yield a fuel flow proportional to engine speed comprises two dump outlet paths each controlled by a metering orifice and a flowresponsive valve which up to a predetermined first rate of flow from the pump permits escape through both metering orifices and then, up to a predetermined higher rate of flow, progressively cuts off the escape path through one of the metering orifices whilst leaving the fuel escape path through the other metering path unaffected. A gear pump 1 draws fuel from a tank 2 and supplies it to the engine burner 6 through a valve assembly 4 and governor speed-control 5. The valve assembly 4 is an acceleration control and comprises a flowresponsive valve 7 and two needle valves 8, 9. The valve 7 comprises a spring-loaded piston 10 which separates, except for metering apertures 11, an inlet chamber 12 and outlet chamber 13. The chamber 13 has a permanently open port leading port needle valve 8 to the fuel supply 15. A second port 16 controlled by the piston 10 leads to the needle valve 9. When fuel is delivered by the pump 1 the pressure drop across the metering apertures 11, which varies with the rate of flow, will tend to move the piston 10 against the action of spring 17. At a predetermined rate of the flow the piston 10 will move and start to close the port 16 until at a higher rate of flow the port 16 is shut off. This will cause an increase in the rate of increase of fuel flow against speed which is necessary if the engine is to have maximum acceleration without overheating.