| 摘要 |
PROBLEM TO BE SOLVED: To prevent a catalyst erosion by an exhaust gas getting extremely high temperature in a high load high rotation area, with a simple structure.SOLUTION: An engine body 2 is arranged in an engine room 4 in a posture of a crank axis being lateral, and on a front surface 1a of a cylinder head 1, a collecting pipe 5 for configuring an upstream part of an exhaust passage is fixed. The collecting pipe 5 is bent downward, and a catalytic converter 9 is integrally connected to a lower end. At a downward part 5c of the collecting pipe 5, a hollow pipe 14 is arranged in a posture of traversing a flow of the exhaust gas. The hollow pipe 14 opens front and back, and the exhaust gas is cooled by travel wind flowing inside. As a result, abnormal temperature rise of a catalyst can be prevented. The exhaust gas is agitated by the hollow pipe 14, so that detection accuracy of an air-fuel ratio sensor 12 is enhanced, and dispersibility of the exhaust gas with respect to a purification unit is also enhanced. |
