| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To control the air fuel ratio becoming maximum conversion efficiency of a catalyst even when an error is caused between a sensor output value and the actual air fuel ratio by the deterioration and a fluctuation of air fuel ratio sensors. <P>SOLUTION: An oxygen storage quantity Os of the catalyst is calculated on the basis of the air fuel ratio detected by the first air fuel ratio sensor on the upstream side of the catalyst. When this calculation value Os falls within a proper range, the air fuel ratio detected by the second air fuel ratio sensor on the downstream side of the catalyst is not in the vicinity of the stoichiometric air fuel ratio. When the air fuel ratio is determined as rich, a desired value Oa is increasingly corrected by increasingly correcting an upper limit value of the oxygen storage quantity. When the air fuel ratio is determined as lean, the desired value Oa is decreasingly corrected by decreasingly correcting a lower limit value of the oxygen storage quantity. <P>COPYRIGHT: (C)2004,JPO</p> |
