| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a technology with which an air fuel ratio of exhaust gas flowing in a storage-reduction type NOx catalyst provided to an exhaust passage can be favorably controlled to a target air fuel ratio. <P>SOLUTION: A fuel addition valve 9 is provided to an exhaust passage 3 at the upstream side from a NOx catalyst 6. An upstream side air fuel ratio sensor 11 is provided to the exhaust passage 3 on the upstream side from the fuel addition valve 9. A downstream side air fuel ratio sensor 12 is provided to the exhaust passage 3 at the downstream side from the NOx catalyst 6. A catalyst 8 having oxidation function is provided to the exhaust passage 3 at the upstream side from the upstream side air fuel ratio sensor 11. <P>COPYRIGHT: (C)2009,JPO&INPIT |
