| 摘要 |
PURPOSE:To improve antiknocking property, by a method wherein an exhaust port is opened in a position opposite to a first suction valve port, an ignition source is disposed in a position opposite to a second suction valve port, and the area of each of the suction valve ports and that of the exhaust valve port are set to specified values respectively. CONSTITUTION:A pair of first and second suction valve ports 91 and 92 are formed on a ceiling slope 71 of a combustion chamber, and an exhaust valve port 10 is provided on other ceiling slope 72. Further, an ignition plug 11 is disposed in a position facing the second suction valve port 92. The distance from the ignition source to the periphery of combustion chamber can be made almost equal, and the propagating distance of flame is shortened, resulting in the ability to improve antiknocking property. Further, provided the effective areas of the first and second suction valve ports are respectively Ai1 and Ai2, the effective area of the exhaust valve port is Ae, and the effective area of a cylinder is Ac, (Ai1+Ai2)/Ae is equal to 1.3-1.6 and (Ai1+Ai2)/Ac is equal to 0.26-0.32, the suction flow rate properly matches the exhaust flow rate, and high-speed output performance can be further improved. |
