| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve a convergence ability to stoichiometry when an actual exhaust air fuel ratio is near the stoichiometry or lean while performing a rich urging control after completion of an FC control execution, thereby preventing degradation of exhaust emission. Ž<P>SOLUTION: An ECU 1A includes a rich urging control means for performing the rich urging control in which the exhaust air fuel ratio is made richer after completion of a fuel cut control of an engine 50, a rich urging guard value setting means for setting an upper and lower limit guard value of which width is narrower than an upper and lower limit guard value set when a target air fuel ratio is stoichiometry based on a feedback correction amount of an air fuel ratio feedback control while performing the rich urging control, and a lean guard value setting means for setting an upper and lower limit guard values the upper limit guard value of which is greater than the upper and lower limit guard values set by the rich urging guard value setting means instead of the upper and lower limit guard values set by the rich urging guard value setting means when the actual exhaust air fuel ratio is near the stoichiometry or lean while performing the rich urging control. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
|
