| 摘要 |
PROBLEM TO BE SOLVED: To provide an air-fuel ratio control device capable of controlling an oxygen occlusion amount of a catalyst after fuel cut (FC) is recovered to a proper amount, and making emission efficient by properly controlling a period of an air-fuel rich control after the fuel cut is recovered. SOLUTION: This control device executes an air-fuel ratio rich control after FC is recovered, when an oxygen occlusion amount OSA of a catalyst becomes excessive during an FC control. The control device calculates the oxygen occlusion amount based on a target air-fuel ratio abyfr from the FC recovery until "a response delay period" such as gas transportation delay and detection delay of an air-fuel ratio sensor has elapsed (steps 740, 745, 755, and 715). The control device calculates an oxygen discharging amount based on the air-fuel ratio abyft based on an output of the air-fuel ratio sensor (steps 750, 755, and 715). Then, the control device stops the air-fuel ratio rich control when the oxygen occlusion amount becomes not more than a predetermined value. COPYRIGHT: (C)2009,JPO&INPIT
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