Patent GB-1439764-A (GB)
Title: Fuel control systems for gas turbine engines
IPC: F02C9/38
Filed: 1972-08-23
Abstract: 1439764 Gas turbine engine fuel systems; re-heat fuel systems LUCAS INDUSTRIES Ltd 4 Oct 1973 [23 Aug 1972] 39347/72 Addition to 1359650 Headings F1G and F1J In a fuel supply system as claimed in claim 2  of Specification 1359650, the electrical actuator is responsive to an electrical signal proportional to the quantity of fuel delivered by the pump to the inlet of the valve. The system shown in Fig. 1 comprises an engine-driven gear-pump 10 delivering fuel via a control valve 16 operated by an actuator 9 controlled by an electronic unit 15 which receives electrical signals from a flowmeter 14 located downstream of the pump, in addition to electrical signals dependent on, e.g., shaft speed N, compressor intake pressure P 1 , compressor delivery pressure P 2  and intake temperature T 1 . Valve 16 comprises a member 25 movable within a ported sleeve 21 so as to vary the proportions of fuel flowing to an outlet 19 leading to the burners and an outlet 20 connected via a return valve 29 to the pump inlet 11. Valve 29 comprises a member 32 movable within a ported sleeve 30 under the influence of any differential between the pressures at the outlets 19 and 20, whereby these pressures are equalized. In the event of failure of the flowmeter 14, the unit 15 can provide an approximately correct output signal based on the input signal dependent on shaft speed N. The flowmeter 14, the valves 16, 29 and, it may be, the control unit 15 may be duplicated. The pump 10, flowmeter 14, control unit 15 and valve 29 may be common to three valves similar to the valve 16 but feeding separate burners, viz., the primary burner, gutter and collander of an engine re-heat system. Fig. 7 shows a modification of Fig. 1 in which a valve 60, similar to valve 16, is arranged to provide a fuel flow sufficient for  engine starting. During normal running, a solenoid valve 63 is opened to allow the excess fuel flow to be by-passed to the valve 29 via a metering valve 62 which is controlled jointly with the valve 60 by the control unit 15. In Fig. 5, valves 36 and 37 correspond in function to valves 16 and 29 of Fig. 1. Further valves 41, 45 similar to valve 16 and controlled by the unit 15 and associated with further valves 46, 47 similar to valve 29 are connected beyond valve 36 as shown, the effect of the arrangement being that valve 36 determines the total fuel flow while valve 41 proportions this total flow between a first re-heat burner 42 and second and third re-heat burners 43, 44, and valve 45 proportions fuel flow between the burners 43 and 44. In the system shown in Fig. 6, in which a re-heat burner 52 is fed from a valve 16 as in Fig. 1, further re-heat burners 50, 51 are fed from the outlets of respective valves 56, 55 which are similar to the valve 29. The valves 55, 56 receive fuel from respective metering valves 53, 54 controlled by the unit 15 and are connected to the outlet 19 of the valve 16 so as to respond to any differential between the pressure at the outlet 19 and the pressure downstream of the respective metering valve 53 or 54, whereby these pressures are equalized.