| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device of an internal combustion engine for accurately perceiving a NOx storage capacity of NOx storage reduction catalyst. <P>SOLUTION: When NOx storage capacity calculating process is started and it is determined that an output of an NOx sensor is saturated, a rich increase amount factor of a fuel injection amount is adjusted so that an exhaust air-fuel ratio is on a rich side a little than a stoichiometric air-fuel ratio, and a combustion mode is switched to rich control. Then, a period from a time point when a rich air-fuel ratio is detected by a first oxygen sensor to a time point when the rich air-fuel ratio is detected by a second oxygen sensor is calculated, and the NOx storage capacity is calculated on the basis of the period. Then, the NOx storage capacity is calculated by interpolation calculation using the NOx storage capacity of each bed temperature region on the basis of a catalyst bed temperature. The NOx storage capacity is corrected by multiplying the calculated NOx storage capacity by an NOx storage ratio in response to an exhaust gas flow rate. <P>COPYRIGHT: (C)2004,JPO</p> |
