| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device satisfying both of improvement of exhaust emission when exhaust gas temperature is low and maintenance of performance when exhaust gas temperature is high. <P>SOLUTION: This exhaust emission control device 1 has a plurality of purification catalysts 2, 3 arranged in an upstream and a downstream of an exhaust passage 100 of an internal combustion engine 100, cross section area of the purification catalyst 2 in the upstream side can be varied in relation to flow of exhaust gas GA. Since cross section area of the purification catalyst in the upstream side can be varied, deterioration of the purification catalyst due to overheat can be prevented by reducing cross section area of the exhaust passage when the same is warmed up sufficiently. In another side, emission can be improved by largely expanding cross section area of the purification catalyst in the upstream side when exhaust gas temperature is low such as cold start. <P>COPYRIGHT: (C)2007,JPO&INPIT |
