Patent GB-718121-A (GB)
Title: Liquid fuel regulating means for gas turbines and similar engines
Inventor: BELL FRANCIS ROBERT
IPC: F02C7/22
Filed: 1951-12-24
Abstract: 718,121. Gas turbine plant. LUCAS (INDUSTRIES), Ltd., J., and ROVER CO., Ltd. Dec. 22, 1952 [Dec. 24, 1951], No. 30146/51. Class 110(3) [Also in Groups XI and XXIX] Means for regulating the return flow of liquid fuel from a swirl type burner b in the combustion chamber of a jet-propulsion or other gas turbine type of engine comprises a valve A responsive to a fluid pressure related to engine speed and adapted to by-pass a manually adjustable throttle c in the return flow system at a predetermined maximum engine speed and two other valves B, C in the return flow system each responsive to the opposed actions of the fluid pressure which is related to engine speed and to the returned fuel pressure but adapted to operate at different settings of the throttle. In Fig. 1 the burner b is supplied by a pump a from a sump d to which fuel is returned from the throttle c and also directly from the valves A and C. Blower pressure or some other pressure related to engine speed is applied to the valves A, B, C through a connection e. The valve A is the same as that shown in Fig. 1 of Specification 633,565 and comprises a returned fuel duct the inlet of which is controlled by a closure member actuated by a diaphragm responsive to the difference between blower air pressure and returned fuel pressure. The returned fuel duct also has a by-pass controlled by a closure member actuated by a diaphragm and an evacuated elastic capsule both exposed to blower air pressure. Due to the provision of the valve B, the closure member controlling the inlet is not essential. The valve B Fig. 3 which is opened when the throttle is moved'to increase the return flow of fuel comprises a body part t with a returned fuel inlet 2 and outlet 7 and a connection v for blower pressure. The body part is divided into two compartments by a diaphragm u attached to a plate w carrying a poppet valve y. The valve y is urged against a seat provided by a fixed plate z by a spring 5. The plate z has a seat 6 for a closure disc 3 also acted on by the spring 5. The valve y is opened when the clearance between the plate w and a boss 4 is taken up. The blower pressure is effective to do this even at low engine speeds. Subsequently the return fuel flow is regulated by the disc 3. The valve C, Fig. 4, which is opened when the throttle is moved to decrease the return fuel flow comprises a hollow body part 10 with the returned fuel inlet and outlet connections 15, 16 and a blower pressure connection 12. The part 10 is divided into two compartments-by a diaphragm 11. The upper compartment contains a hollow cylindrical member 13 secured to the diaphragm and within the member 13 slides a member 14 adapted to close the end of the inlet 15, a spring 17 being interposed between the members. In Fig. 5, the valves A, B, C are combined with the throttle c in a unitary structure. This comprises a body part 20 with a returned fuel inlet 37 and outlet 24 and blower pressure connections 29, 42. The throttle comprises a tubular member 22 operated by rack and pinion mechanism 23. The opening movement of the throttle is limited by an adjustable stop 25. The throttle operates in a bore 21 supplied with fuel through passages 26, 27. The parts corresponding :to the valve B comprise a diaphragm 28 actuating a spring-loaded balanced piston valve 35 through a stem 31 and a spring-loaded closure disc 32 cooperating with a fixed seating 34. The valve C takes the form of a disc 46 co-operating with a fixed seat member 47 having fuel passages 50. The disc 46 is loaded by a .relatively stiff spring 48 abutting a diaphragm 40 itself loaded by a lighter spring 41. The valve A comprises a poppet valve 45 carried by a boss 44 clamped to the diaphragm 40. The clearance between the boss 44 and the disc 46 enables the valve 45 to open when the disc 46 is seated and gaps 49 permit fuel to pass between the parts 44, 46.