| 摘要 |
PROBLEM TO BE SOLVED: To bring a catalyst into contact with the exhaust air just discharged from an engine to enhance the warming property of the catalyst by providing port catalysts independently within a plurality of branch pipes. SOLUTION: A flange 10 to be mounted on the cylinder block of an engine has four openings 10a-10d in the parts to be connected to the exhaust part of each cylinder. Four branch pipes 12a-12d are connected to the openings of the flange 10, respectively. One end of an exhaust manifold is connected to the branch pipes 12a-12d and the other end is connected to a collection part 14 to connect the exhaust manifold to an exhaust pipe from there. Port catalysts 16a-16d are filled in the respective parts just under the flange 10 of the branch pipes 12a-12d. The port catalysts 16a-16d are arranged in the parts extremely close to the exhaust part of the engine, so that the temperature of the port catalysts 16a-16d can be quickly raised to a high temperature by the exhaust of the engine. Therefore, the purification of exhaust gas at the start of the engine can be sufficiently performed.
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