Patent ID: 7240671

Claim:
A control apparatus for controlling operation of an internal combustion engine, comprising: air-fuel ratio detecting means provided in an exhaust system of the internal combustion engine, for detecting an air-fuel ratio to be used to control operation of the internal combustion engine; RPM detecting means for detecting RPM to be used to control operation of the internal combustion engine; an intake pipe pressure sensor for detecting an intake pipe pressure to be used to control operation of the internal combustion engine; coolant temperature detecting means for detecting a coolant temperature to be used to control operation of the internal combustion engine; air-fuel ratio state determining means for determining whether the air-fuel ratio detected by the air-fuel ratio detecting means is in a rich state or in a lean state; characteristic retaining means for retaining an integral gain characteristic in which a value of an integral gain is determined by RPM and an intake pipe pressure, a proportional gain characteristic in which a value of a proportional gain is determined by RPM and an intake pipe pressure, and a coolant temperature coefficient characteristic in which a coolant temperature coefficient for correcting the integral gain is determined according to a coolant temperature; and fuel correction amount calculating means for multiplying the integral gain by the coolant temperature coefficient in calculating a correction amount of a fuel injection amount using a sign obtained from a determination result of the air-fuel ratio state determining means, the integral gain, and the proportional gain, wherein the coolant temperature coefficient of the coolant temperature coefficient characteristic is set to be smaller than a constant value in a region where the coolant temperature is lower than a constant temperature.