| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine, comprising a NOx storage-reduction catalyst device arranged on the downstream side of a combined part between a first exhaust passage for a first cylinder group and a second exhaust passage for a second cylinder group for carrying out lean-burn operation wherein the worsening of exhaust emission at the beginning of temperature rise control is suppressed during the temperature rise control of the NOx storage-reduction catalyst device. <P>SOLUTION: In the exhaust emission control device, the first exhaust passage 2a has a longer passage length than the second exhaust passage 2b. During the temperature rise control of the NOx storage-reduction catalyst device 6, exhaust gas of a set rich air-fuel ratio is exhausted from one of the first cylinder group 1a and the second cylinder group 1b and exhaust gas of a set lean air-fuel ratio is exhausted from the other. The exhaust gas of the set lean air-fuel ratio or the set rich air-fuel ratio is exhausted from the second cylinder group later than the exhaust gas of the set rich air-fuel ratio or the set lean air-fuel ratio is exhausted from the first cylinder group. <P>COPYRIGHT: (C)2007,JPO&INPIT |
