GB587565A - Improvements relating to pressure sensitive control devices for aero-engines - Google Patents

Abstract

587,565. Controlling aero-engines. POWER JETS, Ltd., and WALKER, D. N. Aug. 14, 1942, No. 11444. [Class 7 (vi)] A control system for a gas turbine or other aero engine comprises a separate air compressor of predetermined or controllably variable compression ratio driven by the engine and a pressure responsive device acted upon by the air pressure generated by the compressor and in its response thereto controlling the engine, with or without the co-operation of a manual control. The compression of a pump comprising a cylinder 20, Fig. 2, and piston 21 is controlled by, a plunger 29 adjusted by a cam 29B against the pressure of a spring 29A and the discharge pressure acts on a ram 25, displacement of the ram causing a cam 25A to vary the tension of a spring 27 which loads a fuel relief valve 28 and thus determines the pressure of the fuel supply and speed of the',engine. The cam 25A may compress' or ease the spring 27 through a lever the opposite end of which is positioned by a cam which replaces the cam 29B, the plunger 29 being fixed. As shown in Fig. 4, the pump has a pre-determined compression ratio and comprises a piston 43 and cylinder 41, the compression chamber of which communicates through a passage 42A with a cylinder 42 open to the atmosphere at its upper end. A piston 45 on the cylinder 42 is actuated by the crankpin 43C of the pump piston 43 through a link 44 the outer end of which is manually adjustable to, vary the stroke of the piston 45 and the time when it closes ports leading from the passage 42A into the cylinder 42. The outlet of the pump is connected to a pipe 50A, Fig. 5, communicating with the upper side of a diaphragm 56 loaded by a spring 57. A plunger 53 operatively connects the diaphragm 56 to a relief valve 51 on the fuel supply line 5, the pressure at which the valve lifts determining the speed of the engine. A reservoir between the pump and the relief valve may prevent unduly rapid changes in the fuel supply, especially at low speeds. As the pump operates at a definite compression ratio the discharge pressure varies with the atmospheric pressure and compensates for altitude changes.