GB620197A - Improvements in or relating to fuel-systems for gas-turbine engines - Google Patents

Abstract

620,197. Fluid-pressure servomotor-control systems. DAVIES, K. R. Jan. 7, 1947, No. 584. [Class 135] [Also in Groups XXVI and XXVIII] A pump 38 driven from the turbine delivers oil through an orifice 33. A turbine control lever 35 positions a valve 34 and the pressuredrop across the orifice 33 is used to determine the rate of supply of fuel to the combustion chambers. In the pump shown, a swash-plate 15 is driven by an oblique crank 16 on a turbinedriven shaft and the stroke of the plungers 11 is varied by an axial shift of the crank. This is effected by a piston 17 subjected on one side to the pressure of a spring 25 and on the other to the fluid pressure in the space 39. This fluid pressure is maintained by a turbine-driven pump 26 and is varied by means of a leak valve 29. The leak valve is directly connected by an arm 30 to a capsule 31 which is subjected to the pressure-drop across the orifice 33. A delaying action is imposed by a second capsule 41 connected to the cylinder 18 and provided with a restricted orifice 40. It is connected to the arm 30 by a hook device 42 with some lostmotion. Flow in and out of the cylinder 18 is by way of the orifice 40 and distortion of the capsule 41, beyond the amount of the lost motion, will oppose the action of the capsule 31. The area of the orifice 40 may be varied by means of a barometric device. In the pump shown, the suction and delivery valves are ports 22 in a disc 20. The disc is toothed peripherally and meshes with a fixed annulus 23. It is given a gyratory motion by an eccentric 19 on the shaft of the crank 16. The cylinders 12 have separate delivery pipes 13, each to its associated burner 14, and the flow in the pipes 13 is smoothed by means of crossconnected passages containing pistons 24. Specification 618,486, [Group XXVI], is referred to.