GB652321A - Improvements in apparatus for controlling the fuel supply to engines - Google Patents

Abstract

652,321. Gas turbine plant. BENDIX AVIATION CORPORATION. June 15,1948, No. 16132 Convention date, June 26, 1947. [Class 110(iii)] [Also in Groups XXIX and XXXIV] Apparatus for controlling the fuel supply line to a gas turbine comprises a throttling valve having end portions or pistons 44, 45 of different effective area supplied with fluid under pressure through conduit means 50, 52 having a restriction 53 in the part between the portions or pistons 44, 45 and a drain opening 57 adjacent one end portion under the control of a pilot valve 39 actuated in dependence on an engine operating condition. As shown, a gas turbine engine comprises a turbine 3 driving through a shaft 2 a compressor 1 and an alternator 9. The valve 41 controls the fuel supply from a combined oil and fuel pump 15 through conduits 8 to burner nozzles 7 in combustion chambers supplied with air from the compressor 1. The fuel regulating apparatus 14, Fig. 1, is shown in detail in Fig. 2. The pump 15 comprises opposed fuel pump pistons 17 and opposed oil pump pistons 18 all driven from an eccentric 19 in turn driven from the engine through a shaft 16. The pistons 18 constantly supply a chamber 51 through the conduit 50. The chamber 51 communicates with a further chamber 56 through a conduit 52, a chamber 54 and a passage 55. The pilot valve 39 when open causes the pressure in the chamber 54 and hence the chamber 56 to diminish so that the throttling valve 41 tends to close valve ports 43, 47 and open byepass ports 48. The valve 39 is biassed against a lever 33 by a spring 40. The lever 33 is controlled at one end. by a centrifugal governor 30 driven through a shaft 31 from the engine and at the other end by a solenoid 37 the core 35 of which supports a fulcrum pin 34. The solenoid 37 is connected across a shunt resistance 66 in circuit with one of the leads 11, 12 between the exciter 10 and the field of the alternator 9. The speed setting of the governor 30 is thus modified in accordance with the electrical load applied to the alternator through leads'13. The apparatus thus provides "speed droop" as the load increases. A pin 75 actuated by a spring-loaded bellows 70 exposed internally to the fuel pressure in the nozzle lines 8 and externally to the compressor outlet pressure through a pipe 73, operates on the lever 33 and hence controls the valve 41 to prevent the air-to-fuel ratio from falling below a predetermined safe minimum value. If the engine over speeds, a centrifugal pump 75a driven from the engine and having radial channels 76 creates sufficient pressure difference across a spring-loaded diaphragm 79 to withdraw a trip pin 84 from beneath a spring-loaded plunger 85 having a manually operable resetting knob 87. On release, ,the plunger 85 cuts off the pressure conduit 50 and positively moves the valve 41 down to shunt off the fuel supply. The plunger has a stem 89 engaging a bore 90 and having a drain passage 91.