| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device having an improved exhaust emission control performance. <P>SOLUTION: This exhaust emission control device comprises an NOx trap catalyst 15 storing the NOx in the exhaust emission of an internal combustion engine 1, an air-fuel ratio regulating means 31 for regulating the air-fuel ratio of the exhaust emission, an NOx purge execution means 33 for executing NOx purge treatment for changing the exhaust emission air-fuel ratio to an air-fuel ratio for purging for a predetermined purge time when the requirements for executing NOx purge are satisfied, an NH<SB>3</SB>detection means 17 for detecting the NH<SB>3</SB>in the exhaust emission, an HC concentration estimating means 34 for estimating the concentration of the HC in the exhaust emission based on the results of the detection of the NH<SB>3</SB>detection means 17 when the air-fuel ratio of the exhaust emission is richer than the theoretical air-fuel ratio, and an NOx purge condition correction means 34 for correcting the purge time and/or the air-fuel ratio for purging based on the results of the estimation of the HC concentration estimating means 34. <P>COPYRIGHT: (C)2008,JPO&INPIT |
