Air-fuel ratio control apparatus for internal combustion engines

Claim 1

In an electronic air-fuel ratio control apparatus for an internal combustion engine including a throttle actuator for varying the opening of a throttle valve arranged in an intake passage of said engine and at least one fuel injection valve positioned upstream or downstream of said throttle value to inject fuel, thereby controlling the air-fuel ratio of a mixture supplied to the combustion chambers of said engine, the improvement comprising: first sensor means for detecting the rotational speed of said engine and for producing an output signal representative of said rotational speed; second sensor means for detecting an operation command quantity by a driver and for producing an output signal representative of said quantity, including means for detecting an acceleration command by the driver; first computing means responsive to output signals from said first and second sensors for computing at periodic intervals a quantity of fuel to be injected from said fuel injection value; and second computing means responsive to said fuel injection quantity computed by said first computing means at each of said periodic intervals for computing an optimum throttle opening for the computed quantity of fuel to be injected and for driving said throttle actuator to attain said optimum throttle opening independent of the quantity of the driver operation command, including means responsive to detection of said acceleration command by said second sensor means for driving said throttle actuator with a predetermined delay to provide fuel enrichment during acceleration.