PURPOSE: To release shock or disorder feeling when an air-fuel ratio is switched accord ing to acceleration and a running load, constitute an air-fuel ratio control device at a low cost, carry out control of the air-fuel ratio without being superposed on torque reducing control of an automatic transmission, and reduce the discharging amount of NOx.
CONSTITUTION: An air-fuel ratio control device for an internal combustion engine is provided with an engine rotational speed detecting means 112, an intake air flow amount detecting means 107, a car speed detecting means 113, an acceleration detecting means 103, an air-fuel ratio change rate calculating means 104 for changing the change rate of an air-fuel ratio, and a target air-fuel ratio calculating means 105 for switching the air-fuel ratio by a change rate calculated in synchronism with a constant control cycle. And also it is provided with an air-fuel ratio map 101 for deciding a target air-fuel ratio on the basis of various kinds of parameters in operating condition, a fuel injection amount calculating means 102 for calculating a fuel injection amount from an intake air amount and the target air-fuel ratio, a fuel injection means 110, an ignition timing control means 106 for changing the ignition timing by the target air-fuel ratio, an ignition means 111, a transmission condition detecting means 115 of a transmission, and a transmission control means 116.
NOGI TOSHIJI
KURIHARA NOBUO
