| 摘要 |
PURPOSE:To improve the engine performance by providing a plurality of exhaust passages and disposing an exhaust gas throttle valves in a part of the passages in order to eliminate the possibility that when the equivalent length of an exhaust pipe is controlled by the exhaust throttle valve, the throttle valve may disturb the flow of exhaust gas. CONSTITUTION:Two intake ports 3 and two exhaust ports 4 are formed in the cylinder head 2 of an engine 1 and opening and closing valves 6 and 7 are disposed in the ports 3 and 4, respectively. Exhaust pipes 11 and 11' are connected to the exhaust ports 4 and each of the exhaust ports 4 and each of the exhaust pipes 11 and 11' constitute an exhaust passage 12 or 12'. The lower side end of each of the exhaust pipes 11 and 11' meet each other and are connected to a silencer 13. An exhaust throttle valve 14 is disposed in one 12 of the exhaust passages 12 and 12' and driven by an electrically coinciding means 15. When the revolutional speed of the engine 1 is increasingly raised, the valve 14 is driven to open the exhaust passage 12 in steps. |
