| 摘要 |
<p>An NOx adsorbent is arranged in an exhaust passage of an internal combustion engine, a fuel addition valve (28) is arranged in the exhaust passage upstream of the NOx adsorbent, and, when the NOx adsorbent should be made to release the NOx, the fuel addition valve (28) adds fuel to the NOx adsorbent in the required fuel addition amount to make the air-fuel ratio of the exhaust gas flowing into the NOx adsorbent temporarily rich. In this case, the required fuel addition amount is added divided into a plurality of operations. The fuel addition rate of the fuel addition valve (28) is detected and the overall addition time from the start of the initial divided addition to the end of the final divided addition is corrected in accordance with the fuel addition rate. Further, the divided addition time, interval, or number of divided additions is corrected so that the amount of fuel actually added from the fuel addition valve (28) is maintained at the required fuel addition amount.</p> |
