| 摘要 |
<p>A cylinder structure satisfies the following conditions: 12% ‰¤ d/a ‰¤ 27%, where d is a distance between a cylinder inner surface 12a and an exhaust valve member 20b, and a is a diameter of the exhaust valve member; 40% ‰¤ c/b ‰¤ 50%, where c is a length of a non-guided portion of the exhaust valve 20 located below a lower end of a sleeve 26 when the exhaust valve 20 is closed, and b is a diameter of a cylinder bore; and 0.5% ‰¤ e/S ‰¤ 0.8%, where e is a gap between an exhaust valve rod 20a and the sleeve 26 and S is a diameter of the exhaust valve rod 20a. With the distance d increased, the length c of the non-guided portion shortened, and the gap e reduced, there is no unevenness in the flow of combustion exhaust gas g around the exhaust valve member 20b so that the exhaust valve member 20b does not contact the valve seat 24 on one side only, which prevents uneven wear on these components.</p> |
