| 摘要 |
<P>PROBLEM TO BE SOLVED: To suppress heat load applied to a catalyst installed on the upstream side of an NOx trap catalyst in NOx regeneration. <P>SOLUTION: In the NOx regeneration, a target equivalent ratio TFBYA is set to a value RS larger than 1, and the air-fuel ratio of exhaust gas is controlled rich. The reducer concentration of the exhaust gas is detected by an exhaust gas sensor installed on the downstream side of the upstream side catalyst. When the concentration reaches a specified value HSen, the storage oxygen of the upstream side catalyst is considered to be consumed and the target equivalent ratio TFBYA is switched to a value RS3 larger than the values RS1 and RS2 before consumption. The target equivalent ratio TFBYA RS3 after the consumption is reduced with the elapse of time. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
