| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine, capable of preventing exhaust emission from deteriorating even if fuel having a high distillation temperature or being rich in aroma components is supplied and an in-cylinder temperature becomes high. <P>SOLUTION: The exhaust emission control device includes: an in-cylinder fuel injection valve; a NOx storage reduction type catalyst disposed in an exhaust system; and an exhaust addition valve disposed in the exhaust system upstream of the catalyst. The exhaust emission control device acquires a fuel property value according to a level of the distillation temperature or a degree of richness in aroma components of the fuel. The higher the in-cylinder temperature becomes, the lower fuel property threshold value the exhaust emission control device acquires. If there is a NOx reduction request and the fuel property value is lower than the fuel property threshold value, a rich spike is performed under a rich combustion control in which fuel is injected through a fuel injection valve so as to be burned in a ratio not more than a theoretical air fuel ratio. On the other hand, if there is a NOx reduction request and the fuel property value is not lower than the fuel property threshold value, a rich spike is performed under an exhaust addition control in which the exhaust addition valve adds a reducing agent into exhaust gas. <P>COPYRIGHT: (C)2011,JPO&INPIT |
