GB1147751A - Fuel supply control systems - Google Patents

Abstract

1,147,751. Fluid-pressure servomotor systems. JOSEPH LUCAS (INDUSTRIES) Ltd. June 24, 1966 [April 9, 1965], No. 15134/65. Heading G3P. [Also in Division F1] A fuel supply system for a gas turbine engine comprises a variable output pump, a throttle valve, and an engine driven hydraulic signal generator capable of producing a signal which is a function of engine speed, and a further valve to which this signal is applied the servocontrol unit of the pump being so connected as to vary the pump output in response to the pressure drop across the throttle valve and the further valve. The system shown in Fig. 1 comprises a swash-plate type pump 10, the swash-plate 11 of which is controlled by a servo device 12, the fuel delivered by the pump passing through a throttle valve 13 which may be a metering valve, a further valve 14 and thence through line 19 to the combustion equipment. The hydraulic signal generator 15 which is driven by the engine produces a pressure signal proportional to engine speed and this pressure is applied through line 17 to the further valve 14 which thus controls the orifice 18. The pressure drop across the throttle valve 13 is proportional to the square of the engine speed. In a second embodiment Fig.2, a hydraulic potentiometer comprising a fixed restriction 20 and a variable restriction 21 is connected across the hydraulic pressure signal generator 15 and the mean pressure of the potentiometer is applied to the piston of the further valve 14. The variable restriction 21 is controlled in dependence on fuel temperature and may possibly be adjusted for different fuel densities. A bleed passage 22 is provided from the line 17 to allow escape of air from the centrifugal pressure generator.