| 摘要 |
PURPOSE:To aim at enhancing the inflow efficiency of intake air and so forth, by providing such an arrangement that the upper and lower sections of an intake air passage in the part where the intake air passage crosses a bore are enlarged in diameter in both directions on the inlet and outlet sides of a venturi section while they are continuous with the slide surface of a piston valve in the venturi section. CONSTITUTION:An intake air passage 3 is formed in a circular cross-sectioned shape in the parts in front and rear of a venturi section, and a bore 5 is also formed in a circular cross-sectioned shape. An enlarged diameter section 10 which increases in diameter (width) in both directions while which is continuous with the slide surface 5a of a piston valve in a venturi section 7, is formed in the lower section of the intake air passage 3 on the outlet side of the venturi section. With this arrangement, air R flows into the venturi section 7 where the air evaporates fuel from a needle jet 9 to form a mixture. Due to the provision of the diameter enlarged section 10, the mixture flows toward the outlet side of the venturi section without being subjected to no large resistance by the venturi section 7, and therefore, it is possible to enhance the inflow efficiency of intake air flowing into the combustion chamber.
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