| 摘要 |
PROBLEM TO BE SOLVED: To smoothly discharge an exhaust gas and improve fuel consumption, by providing a primary exhaust passage which extends downstream of an exhaust introducing portion and has a tapered portion becoming thinner toward its end, and a secondary exhaust passage concentrically surrounding the primary exhaust passage, wherein both exhaust passages communicate with each other through a secondary exhaust inlet port located upstream of the tapered portion. SOLUTION: An exhaust gas travelling as a warhead-like travelling wave enters a front cylindrical portion 2a of a primary exhaust passage 2 through an exhaust introducing portion 1, and then, enters a rear tapered portion 2b of the primary exhaust passage 2. The exhaust gas collides with the inner wall of the tapered portion 2b, and travels against resistance toward a primary outlet port 3 located in the center having the lowest flow rate. The travelling pulsed exhaust gas is rapidly pressurized upon collision with the tapered wall, whereby the exhaust gas having a low flow rate is forced into a secondary exhaust passage 4 through a secondary exhaust inlet port 5. Thus, the exhaust gas travelling near the inner wall of the exhaust piping, i.e., the exhaust gas that is likely to be stagnant, is quickly discharged, thereby improving intake and exhaust states of the internal combustion engine.
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