Patent ID: 9567931
Date: 2017-02-14
CPC Classifications: F02D

Claim:
1. A cylinder-by-cylinder air-fuel ratio controller for an internal combustion engine that is provided with an air-fuel ratio sensor detecting an air-fuel ratio of an exhaust gas at a confluent portion into which the exhaust gas flows from multiple cylinders of the internal combustion engine; a cylinder-by-cylinder air-fuel-ratio estimation portion estimating the air-fuel ratio of each cylinder based on a detection value which the air-fuel ratio sensor detects at an air-fuel ratio detecting time for each cylinder; and a cylinder-by-cylinder air-fuel ratio control portion executing a cylinder-by-cylinder air-fuel ratio control in which the air-fuel ratio of each cylinder is adjusted based on the estimated air-fuel ratio of each cylinder, the cylinder-by-cylinder air-fuel ratio controller comprising: a first time-correction portion correcting the air-fuel ratio detecting time in such a manner that a dispersion of the detection values of the air fuel ratio sensor becomes maximum in one cycle of the internal combustion engine; and a second time-correction portion correcting the air-fuel ratio detecting time in such a manner that the air-fuel ratio detecting time is varied by a combustion interval of the internal combustion engine or the air-fuel ratio detecting time is varied by a multiple of the combustion interval that is two or more, when it is determined that the air-fuel ratio detecting time deviates after the first time-correction portion corrects the air-fuel ratio detecting time.