| 摘要 |
PURPOSE:To enable introduction of secondary air uninfluenced by water and mud splashed by a front wheel and to permit a car body frame to additionally serve as a secondary air feed line, by a method wherein an introduction port for secondary air for purifying exhaust gas is situated to the side of the car body frame located in the rear of an engine. CONSTITUTION:With an engine run, a positive and a negative pressure are generated in an exhaust pipe 7. When the pressure is reduced to a negative pressure, a check valve 6 is opened by means of a difference in a pressure between the open air and the interior of the exhaust pipe, and the open air is introduced through a secondary air introduction part 4 to the interior of the exhaust pipe 7. The open air flows through, in order, a main pipe 1, a coupling pipe 3, and a down tube 2 to the check valve 6, and flows in the exhaust pipe 7 from the other end side of a pipe member 5. Thereafter, secondary air flows to an exhaust gas recombustion device 8 additionally serving as a muffler, and reburns exhaust gas. In this case, since the secondary air introduction port 4 is situated to the side of a car body frame B located in the rear of an engine, secondary air uninfluenced by water and mud splashed by a front wheel 11 can be introduced.
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