Electronic control fuel injection system for spark ignition internal combustion engine

Claim 1

An electronic control fuel injection system for a spark ignition internal combustion engine for preferentially determining fuel flow rate according to the stroke of an accelerator pedal and subordinately determining airflow rate to the engine in response to the fuel flow rate and the engine operating state comprising: an air intake passage having a throttle valve therein for supplying air to said engine; a fuel selecting mechanism for selecting a fuel discharge amount in accordance with a depression stroke of an accelerator pedal; an exhaust gas recirculation rate control device; at least one fuel injector for injecting said selected fuel discharge amount into said engine; means for detecting the amount of intake air to said engine comprising first means for providing a signal representing a pressure difference in said air intake passage on the upstream and downstream sides of said throttle valve, and a second means for providing a signal representing the actual opening position of said throttle valve; an engine rotational speed detecting sensor; an engine temperature sensor; a computer for selectively receiving signals from said fuel selecting mechanism indicating a selected fuel discharge amount, from said first means for providing a signal representing said pressure difference, from said second means for providing a signal representing the actual opening position of said throttle valve and from said rotational speed and temperature sensors, for producing from the signal from said fuel selecting mechanism a first fuel supply output signal which controls the amount of fuel injected by said injector so that said selected fuel discharge amount is supplied to said engine, and for producing from said pressure difference signal, from a signal representing an injected fuel flow amount, and from the signal indicating the actual opening position of said throttle valve, a second optimum air supply amount output signal, said computer adjusting at least one of said first and second output signals in accordance with the signal from said temperature sensor, said computer further producing from the signal from said rotational speed detecting sensor a fuel limiting signal, the amount of fuel discharged by said injector being limited independently of the depression stroke of the accelerator pedal in response to said fuel limiting signal, said computer also producing a third output signal which controls said exhaust gas recirculation rate control device in response to said engine rotational speed signal and said signal representing the selected fuel discharge amount; and, a throttle valve control mechanism for setting the opening of said throttle valve according to said second output signal from said computer to provide an optimum air supply amount to said engine.