| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a technique for more efficiently reducing NOx stored in an NOx catalyst in an exhaust emission control system for an internal combustion engine. <P>SOLUTION: In reducing NOx stored in the NOx catalyst, when a temperature of the NOx catalyst is lower than a prescribed temperature, the air-fuel ratio of an atmosphere around the NOx catalyst is lowered by only lowering the air-fuel ratio of exhaust emitted from the internal combustion engine. In the case that the temperature of the NOx catalyst is the prescribed temperature or higher, the air-fuel ratio of the atmosphere around the NOx catalyst is lowered by only adding a reducer by a reducer adding means, or both by lowering the air-fuel ratio of exhaust emitted from the internal combustion engine, and by adding the reducer by the reducer adding means. <P>COPYRIGHT: (C)2009,JPO&INPIT |
