| 摘要 |
PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal-combustion engine capable of raising the temperature of a catalyst effectively and quickly. SOLUTION: A first cylinder group 1a and a second cylinder group 1b are connected with a three-dimensional catalyst 12 through Y-pipes 3 and 4, and then connected with a NOX catalyst 11. The air-fuel ratio of the exhaust gas flowing through a branch part 3a of the Y-pipe 3 is held lean while the air-fuel ratio of the exhaust gas flowing through another branch part 3b of the Y-pipe 3 is held rich for raising the temperature of the NOX catalyst 11, and the mean air-fuel ratio of the whole exhaust gas flowing into the three-dimensional catalyst 12 at this time is made the theoretical air-fuel ratio or richer to a minor extent. At the divergent part 4c of the Y-pipe 4 revolving device 13 is installed to guide the exhaust gas so that it revolves approximately round the axis of the divergent part 4c of the Y-pipe 4, and the exhaust gases from the two branch parts 3a and 3b are mixed together by the revolving device 13. COPYRIGHT: (C)2004,JPO
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