GB866988A - Improvements in or relating to the fuel feed systems of turbojet engines - Google Patents

Abstract

866,988. Fluid-pressure servomotor control systems. SZYDLOWSKI, J. Feb. 12, 1958 [Feb. 20, 1957], No. 4641/58. Class 135. [Also in Group XXVI] A fuel feed system for a turbojet engine 18 comprises a fuel metering valve 11 actuated by a servo-device comprising a piston 19 and speed-sensitive control valve 24 with a temporary followup action, and means comprising a valve 57 actuated by a bellows 61 subject to the delivery pressure of the compressor of the engine for limiting the speed at which the metering valve is actuated. Fuel is delivered by a pump 1 and conduit 5 to a valve 13 which is subject to the pressures on either side of the metering valve 11 so as to control the pressure difference across the latter, this pressure difference being governed by the force exerted by a loading spring 14 which is adjusted by a servo-piston 68 under the control of a valve 64 which is actuated by a bellows 74 subject to the total head pressure at the inlet to the compressor. A rack and pinion 72, 71, a cam 70, and a lever 69 constitute a follow-up connection between the servopiston 68 and the valve 64. Fuel leaving the valve 13 passes to the metering valve 11, thence to a valve 16 actuated by a throttle control lever 36 and finally to the burners 17 of the engine. The lever 36 also acts on an adjustable loading spring 32 of the valve 24 for setting the speed of the engine. The temporary follow-up between the servo-piston 19 and the valve 24 consists of an adjustable restriction 23, a spring- loaded piston 20, and connections from each side of the pistons 20 to opposite ends of the valve 24. This arrangement is described in Specification 860,283. The arrangement for limiting the speed at which the metering valve 11 operates consists of the member 57 which is rotated by the engine and controls the outlets from conduits 54, 55 through one of which the servo-piston 19 is exhausted when the valve 24 is moved from its neutral position. The degree of obturation of the outlets from the conduits 54, 55 is determined by the bellows 61. The valve 24 is rotated by an oil-driven turbine 53 to reduce static friction. A small pump (not shown) for engine starting is fed through a valve 80 which is opened for a limited period by an electric relay 81.