| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a technology for immediately removing oxygen stored in a catalyst and immediately recovering the conversion capacity of the catalyst, in an exhaust emission control device for an internal combustion engine. <P>SOLUTION: This exhaust emission control device for the internal combustion engine includes the first catalyst arranged in the exhaust passage of the internal combustion engine and having an oxygen storage capacity and an oxidation capacity, and the second catalyst arranged downstream of the first catalyst and recovering an exhaust gas conversion capacity by supplying a reducing agent. When the exhaust gas conversion capacity of the second catalyst is recovered, an air-fuel ratio in a cylinder is set to the vicinity of a theoretical air-fuel ratio and also fuel is supplied into exhaust gas, and thereby an exhaust air-fuel ratio is enriched and oxygen in the first catalyst is removed. After that, the air-fuel ratio in the cylinder is made lean and also fuel is supplied into exhaust gas, thereby the exhaust air-fuel ratio is set to the vicinity of the theoretical air-fuel ratio, and the reducing agent is supplied to the second catalyst. <P>COPYRIGHT: (C)2009,JPO&INPIT |
