AIR-FUEL RATIO CONTROL APPARATUS AND AIR-FUEL RATIO CONTROL METHOD FOR INTERNAL COMBUSTION ENGINE

摘要

In an air-fuel ratio control apparatus for an internal combustion engine, a feedforward correction amount obtained in accordance with a deviation of a target air-fuel ratio from a stoichiometric air-fuel ratio and a feedback correction amount calculated on the basis of an output value of an air-fuel ratio sensor and subjected to a guard processing are added to a base fuel injection amount corresponding to the stoichiometric air-fuel ratio to decide a fuel injection amount. An upper limit and a lower limit of the feedback correction amount are set on the basis of an alcohol concentration and the feedforward correction amount.