| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To rapidly reduce the amount of sulfur accumulated in an NO<SB>x</SB>catalyst with simple constitution. <P>SOLUTION: In an exhaust passage of an internal combustion engine where combustion is kept under a lean air fuel ratio, a hydrogen generating catalyst 22 for generating hydrogen out of hydrocarbon in the exhaust gas flowed when the air fuel ratio of the exhaust gas flowed is rich, and the NO<SB>x</SB>catalyst 23 is arranged in the exhaust passage at the downstream of the hydrogen generating catalyst 22. When the amount of the accumulated NO<SB>X</SB>in the NO<SB>X</SB>catalyst 23 is reduced, hydrocarbon is fed from an HC feeding nozzle 30d at the downstream side to change the air fuel ratio of the exhaust gas flowed into the NO<SB>X</SB>catalyst 23 for a rich one. When the amount of the accumulated So<SB>x</SB>in the NO<SB>x</SB>catalyst 23 is reduced, hydrocarbon is fed from the HC feeding nozzle 30<SB>u</SB>at the upstream side to change the air fuel ratio of the exhaust gas flowed into the hydrogen generating catalyst 22 for the rich one. This makes hydrogen H<SB>2</SB>be contained in the exhaust gas flowed into the NO<SB>X</SB>catalyst 23. <P>COPYRIGHT: (C)2004,JPO</p> |
