| 摘要 |
<p>A three-way catalyst (10) is provided in the exhaust passage (9) of an engine (1) which stores and releases oxygen according to the oxygen concentration in the exhaust gas. A controller (2) calculates an oxygen storage amount of the catalyst (10) by accumulating a variation rate of the oxygen storage amount of the catalyst (10) based on the oxygen amount in the exhaust gas (S3-S5). A target oxygen amount in the exhaust gas is calculated which reduces the difference of the oxygen storage amount from a target oxygen storage amount (S6). A target air/fuel ratio is calculated based on a catalyst deterioration coefficient, an exhaust gas flowrate and the target oxygen amount (S7). Due to this process, it is possible to increase the speed and accuracy of control of the oxygen storage amount of the catalyst (10) towards the target oxygen storage amount.</p> |
