| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine achieving improvement of fuel economy, suitable regeneration of NOx absorption catalyst by appropriately reducing fuel quantity for regeneration while maintaining regeneration efficiency according to degree of deterioration of oxidation catalyst. <P>SOLUTION: The exhaust emission control device 1 is provided with the NOx absorption catalyst 17, an oxidation catalyst 16 in an upstream thereof, and ECU 2. The ECU 2 determines a target air fuel ratio KCMD which is a target of air fuel ratio of gas to be burnt in an internal combustion engine 3 for reducing NOx of the NOx absorption catalyst 17 to a first air fuel ratio KCMD1 richer than theoretical air fuel ratio or a second air fuel ratio KCMD2 richer than that according to operation condition of the internal combustion engine 3 during a predetermined time RETM1, RETM2. The target air fuel ratio KCMD is corrected to lean side according to degree of deterioration of the oxidation catalyst 16 when the target air fuel ratio KCMD is the first air fuel ratio KCMD1, and the predetermined time RETM2 is corrected to reduction side according to degree of deterioration of the oxidation catalyst 16 when the target air fuel ratio KCMD is the second air fuel ratio KCMD2. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
