GB1371842A - Otto cycle fuel-injection internal combustion engine - Google Patents

Abstract

1371842 I C engine fuel injection FORD MOTOR CO Ltd 3 Feb 1972 5055/72 Heading F1B Fuel is injected directly into the cylinder of an Otto cycle engine during the induction stroke of the piston 11 in accordance with the mass of air entering the cylinder during each cycle. An outwardly opening electromagnetic injector 19, receiving fuel under low pressure, e.g. 100 p.s.i., is energized by a logic circuit, Fig. 2 having inputs 20 to 26. The air velocity and pressure sensors are mounted in the inlet passage 15 and the temperature and humidity sensors may be mounted to be common to a plurality of cylinders. The output signal of air mass flow from the generator 28 is converted to a frequency in the converter 29 and fed to the counting register 30 so that the register accumulates a count representing the mass of air which has entered the cylinder. The fuel velocity and temperature sensors are mounted in the injector 19 or the fuel supply line and the output signal of fuel mass flow from the generator 38 is converted to a frequency in the converter 39 and fed to the register 30 to reduce the count therein. The up count fed into register input 31 is in a predetermined ratio to the down count fed into input 40 for the same mass flow of air and fuel, 1 : 20 for a 20 : 1 fuel air ratio. Gate circuits 32 to 34 connect a respective stage of the register 30 to the pulse generator, to provide low, intermediate and high or infinite mark/space ratios to the amplifier 36 and injector solenoid 37 dependant upon the count in the register. The amplitude of the pulses is sufficiently high to fully open the injector but the frequency is too high for the injector valve to follow so that the rate of fuel injection is dependent upon mark/space ratio, the valve being more fully open the higher the ratio. The gates 32 to 34 are opened and closed by a bistable circuit 41 which is opened when an electromagnetic device coupled to the engine flywheel produces a signal and closed when the air mass flow falls below a predetermined level and after a time delay sufficient to ensure that the cylinder inlet valve is closed. The register 30 may be set to zero by a monostable circuit 45 when the injection is terminated or the count may be retained for the next cycle so that effectively at high engine speeds the fuel injection during a cycle corresponds to the air-flow in the preceding cycle. For a four cylinder engine two logic circuits each time shared between two cylinders may be provided, only air velocity and pressure and fuel velocity sensors being provided for each cylinder. The intake air may be drawn through a water carburetter providing 100% relative humidity. The injector 19 is cooled by the water jacket 9. The air and fuel flow velocities may be measured by flow meters as described in Specification 1127568 or hot wire or hot film anemometers.