| 摘要 |
PURPOSE:To prevent that the thickness of a cylinder is reduced excessively in an apparatus in which a valve means is provided in the vicinity of an exhaust port of the exhaust passage opened in the inner surface of the cylinder, by disposing the valve means in an inclined manner, and retracting the valve means during high-speed operation of the engine to a position where it is substantially aligned with the inner wall surface of the exhaust passage. CONSTITUTION:In the vicinity of an exhaust port 34 formed in the cylinder body 10 of a two- cycle engine, a hole 36 having a section in the form of an elongated circle with an inclination angle of about 55 deg. to the cylinder axis. In this hole 36, there is fitted a plate valve 38 having a cross section conforming to that of the hole 36, in the manner that it can be slided freely in the hole 36. The top 40 of the valve 38 is curved slightly inward so that it conforms substantially to the arcuate form of the inner wall surface of the cylinder body 10 and also to the form of exhaust passage 30 at its upper portion. To the rear end portion of the valve 38, there is fixed a shaft 42 which is connected via a linkage or the like to an actuator moved in response to the engine speed or the like. With such an arrangement, it is prevented that the thickness of the cylinder body is reduced excessively in installation of the valve 38. |
