| 摘要 |
PURPOSE:To enable to prevent blow-back of intake air with a simple and economical structure, by providing a shield plate at the bottom of an intake passage near an intake port, and erecting the shield plate slantwise toward the intake port at the time of low-speed and medium-speed operation of an engine. CONSTITUTION:The bottom surface 6a of an intake passage 6 near an intake port 5 opened in a cylinder 3 is shaped to have an inclined portion 6b inclined downward in the opposite direction of the intake port 5. In the inclined portion 6b, one end of a shield plate 7 is pivoted by a pivotal shaft 8. Further, one end of the pivotal shaft 8 is extended to the outside through the intake passage 6 so that the top of the shield plate 7 is erected toward the intake port 5 through pivotal movement of a support arm 10 extended from said one end of the pivotal shaft 8. With such an arragement, the shield plate 7 is erected slantwise toward the intake port 5 at the time of low-speed and medium-speed operation of the engine. At the time of high-speed operation of the engine, on the other hand, a rod 17 is pushed upward by a diaphragm 12 of an engine-speed detecting means 11 to turn down the shield plate 7 by the support arm 10. |
