| 摘要 |
PROBLEM TO BE SOLVED: To provide an air-fuel ratio control device of an internal combustion engine capable of well controlling air-fuel ratio even under the circumference in which an intake air amount varies from the injection of fuel to the closing of an intake valve. SOLUTION: A feedback control is performed to so feed back the output of an air-fuel ratio sensor 35 to a fuel injection amount that the air-fuel ratio of the exhaust gas flowing to a catalyst 32 matches a target air-fuel ratio. The estimated calculation value kl_IVC at the valve closing timing of the intake valve 16 is calculated. Using the estimated calculation value kl_IVC, the cylinder air-fuel ratio of a cylinder 10 is calculated. The cylinder air-fuel ratio thus obtained is compared with a predetermined determination value. Based on the comparison, it is determined whether the occurrence of variation of air-fuel ratio is present or not. If the variation of air-fuel ratio is determined to occur, the feedback control is stopped. COPYRIGHT: (C)2009,JPO&INPIT
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