| 摘要 |
PROBLEM TO BE SOLVED: To suppress the exhaust gas interference between two cylinders continuous in ignition order without disturbing catalyst early activation.SOLUTION: In an in-line four-cylinder internal combustion engine, exhaust ports of cylinders #2 and #3 merge together within a cylinder head and are open as one collective exhaust port. An exhaust manifold 5 comprises individual exhaust pipes 6, 7 of cylinders #1 and #4; and a collective exhaust pipe 8, and tip ends of the three exhaust pipes 6, 7, 8 are connected to a catalyst converter 11. A tip end portion of the collective exhaust pipe 8 protrudes into an internal space of a diffuser section 11a as a protruding pipe portion 8a. As a result, an exhaust passage length between the cylinders continuous in ignition order increases. The protruding pipe portion 8a enables early activation of a catalyst without being cooled by outdoor air.SELECTED DRAWING: Figure 2 |
