| 摘要 |
PROBLEM TO BE SOLVED: To improve the exhaust purifying performance by feedback controlling the air-fuel ratio of an engine with an appropriate feedback control gain considering the wasted time in the control. SOLUTION: This air-fuel ratio control device controls the air-fuel ratio for feedback on the basis of an output of an upstream side air-fuel ratio sensor 66 and a downstream side air-fuel ratio sensor 67 respectively provided in the upstream and the downstream of the first catalyst 53 provided in an exhaust pipe 52. This air-fuel ratio control device obtains the maximum oxygen storage quantity Cmax of the first catalyst 53, and changes the feedback control gain for feedback control of the air-fuel ratio in response to the maximum oxygen storage quantity Cmax. Since the wasted time in the control changes in response to the maximum oxygen storage quantity Cmax of the first catalyst 53, feedback control is appropriately performed by deciding the feedback control gain, and the air-fuel ratio in the downstream of the first catalyst 53 is controlled for a target air-fuel ratio with excellent responsiveness, while avoiding a change of the air-fuel ratio for oscillation due to excessive correction. COPYRIGHT: (C)2004,JPO
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