Patent GB-1254181-A (GB)
Title: Fuel injection systems
IPC: F02M69/20
Filed: 1969-01-08
Abstract: 1,254,181. Fluid-pressure servomotor systems. PETROL INJECTION Ltd. AND H. E. JACKSON. March 26, 1970 [Jan. 8, 1969; June 27, 1969; Dec.1, 1969], Nos.1261/69, 32530/69 and 58515/69. Heading G3P. [Also in Division F1] A fuel injection system for an I. C. engine includes a fuel flow path, at least one injector 83 to receive fuel from the path, a fuel metering device 80 to vary fuel flow in response to adjustment of a valve 4 located in the engine air supply path 3 to produce a control pressure differential and an air valve 19 responsive to the pressure differential to adjust the valve 4. The pressure differential is thus maintained at a predetermined value. The valve 4 and the fuel metering device 80 are connected together and to a diaphragm 8 by a linkage 7 biased by a spring 30 to close the valve. When the engine throttle 1 is opened, the fall in pressure in the air path 3 lifts a diaphragm 24 to close the valve 19 and interrupt communication between a vent 18A and the space 17 below the diaphragm 8 which is displaced downwardly by vacuum applied through conduits 9 and 15 and a regulator valve 10. A valve 33 opened by a temperature-responsive strip 34 when the engine is cold, applies vacuum from the valve 10 through conduits 36 and 40 to a diaphragm 23 so that the valve 4 opens until a new equilibrium position is reached and a richer mixture is supplied to the engine. The depression in a chamber 35 containing the valve 33 causes extra air to be supplied through a restriction 37 to the engine. To provide a richer mixture at full power, a valve 100 causes the fuel pressure in a line 63 supplied by a pump 2A to be increased, the valve being actuated by a diaphragm 47 subject to the depression in a line 43 which is connected to atmosphere through a valve 65 actuated by the pressure at a point 3 upstream of the engine throttle 1. A relief valve 57 applies constant pressure to a fuel distributer unit 75 to ensure that the fuel remains liquid at all times and also applies constant pressure to the diaphragm 47 and to a diaphragm 49 to prevent variations in fuel pressure affecting the control system. Fig. 3 shows an alternative system in which opening of the engine throttle 1 causes depression in a line 29 and downward movement of a spring-loaded diaphragm 24 to close a ball valve 21A. Fuel under pressure from a line 56 controlled by a relief valve 57 now flows through the valve 21A and lines 95 and 18 to cause a piston 8A to open the air valve 4 to a position in which equilibrium is reached and the depression in the air path 3 maintained constant. To increase the pressure of fuel supplied to a metering valve 80, a valve 112 controlled by a diaphragm 47 subject to the depression in the air path is provided. A valve 101A may be adjusted manually or automatically to vary the mixture strength. The effect on the depression between the valves 1 and 4 of the flow resistance of the air cleaner may be offset by a conduit 130. The lever 7 of the control system may be coupled to a cam 188, Fig. 5, to operate a fuel metering valve having a tapered slot 194 to co-operate with an aperture 192. The piston 8A in Fig. 3 may be connected by a rack and pinion to a shaft which operates the fuel valve through acam and the air valve 4 through a linkage. The fuel valve may include a pair of restrictors in the lines 80A and 62, one or both of the restrictors being variable. Separate fuel distributors may be used in conjunction with a dual induction manifold of the type described in Specification 1, 229, 914, the distributors being controlled by a pair of solenoid valves responsive to the position of the engine throttle or the vacuum in the air path. In a further modification of the system, the line 43 communicates with the air path at a point between the valves 1 and 4 and is connected to atmosphere through both a fixed restrictor and a cam-operated variable restrictor coupled to the linkage 7.