| 摘要 |
<P>PROBLEM TO BE SOLVED: To optimally supply a reducing agent by each of exhaust emission control devices in the case two emission control devices are arranged in series in an exhaust passage of an internal combustion engine. <P>SOLUTION: Upstream exhaust emission control devices 4, 5 and a downstream exhaust emission control device 6 are disposed in series in the exhaust passage 2, and a bypass passage 9 through which exhaust gas flows to bypass the upstream exhaust emission control devices 4, 5 is provided. Further, a reducing agent adding valve 7 is provided near an upstream end of the bypass passage 9, and a flow passage cross sectional area changing means 8 is provided for allowing change in the flow passage cross sectional area of a portion of the bypass passage 9 directly downstream the reducing agent adding valve 7. <P>COPYRIGHT: (C)2008,JPO&INPIT |
