| 摘要 |
PURPOSE:To obtain a satisfactory intake-air inertia over the entire operating range of a four cycle engine to enhance the charge effect of the four cycle engine, by providing a projecting piece which is projected toward a forward stream side space in a volute type intake-air port swirl stream generating chamber, and by controlling the projecting amount of the projecting piece in accordance with the rotational speed of the engine by use of an extending and retracting amount adjusting means. CONSTITUTION:A volute shape intake-air port spirally communicates the terminal end section of an intake-air inlet port part 15 with the peripheral surface 14a of a swirl stream generating chamber 14, and an intake-air outlet port 16 is opened to the lower end surface of the swirl stream generating chamber 14. In this arrangement, there is provided a projecting piece 20 for guiding intake-air from the intake-air inlet port part 15 to the intake-air forward stream side space 14b remote from the center axis 21 of the swirl stream generating chamber 14 so that the projecting piece 20 is projected into the space 14b from the terminal end section of the inner circumferential side surface 15b of intake-air in the vicinity of the center axis 21 of the swirl stream generating chamber 14 in the inner peripheral surface 15a of the intake-air inlet passage 15. Further, the movement of a governor lever 27 for a governor 26 is transmitted through an extending and retracting amount adjusting means 23 including a wire 25, and therefore, the projecting piece 20 is controlled so that its projecting length is short in a high speed range while its length is long in a low speed range. |
