| 摘要 |
<p>PROBLEM TO BE SOLVED: To accurately calculate a storage oxygen desorption amount of a three-dimensional catalyst. SOLUTION: An upstream air-fuel ratio sensor 23 is arranged in an exhaust passage situated upper stream from a three-dimensional catalyst 18 and a downstream air-fuel ration sensor 24 is arranged in an exhaust passage situated downstream from the three-dimensional catalyst 18. From an air-fuel ratio and an intake air amount detected by the upstream air-fuel ratio sensor 23 and a speed ratio between a desorption speed and an adsorption speed of oxygen at the three-dimensional catalyst 18, a storage oxygen desorption amount is calculated. A speed ratio is corrected such that a storage oxygen desorption amount by calculation coincides with an actual storage oxygen desorption amount.</p> |
