| 摘要 |
PURPOSE:To prevent an accumulation of impurities such as gum material and leakage of air-fuel mixture from occurring and to expedite vaporization of liquid fuel accumulated in a groove, by a method wherein the groove is formed on a wall surface of the bottom of a suction port and a cooling water duct is provided in the vicinity of the groove. CONSTITUTION:When a space between the lower end of a valve plug 31 and a bottom wall surface 21 is blocked completely the valve plug 31 is sticked on the wall surface 21 of the bottom of a titled port by accumulating impurities, such as a gaseous material to be contained in air-fuel mixture on a lower end part of the valve plug 31 as air-fuel mixture collides against the valve plug 31 at the time of a low speed load operation of an engine. To prevent an above-stated matter from occurring a hollowed groove 36 is formed on the wall surface 21 of the bottom of the titled port and a labyrinth seal is formed by the tip part of the valve plug 31 and the hollowed groove 36. But, as liquid fuel becomes accumulative in the groove 36 vaporization of the liquid fuel is expedited by providing a cooling water duct close to the groove 36. |
