| 摘要 |
<P>PROBLEM TO BE SOLVED: To effectively quicken a flow speed of intake air at low speed operation time of an engine, and to effectively reduce flow resistance of the intake air at high speed operation time. <P>SOLUTION: The axis 7A of an intake port 7 in an upstream side part 71 of an installing part of a valve guide 13 is formed in an almost straight shape, and an inclination of an upper wall 7a of the intake port 7 to the cylinder axis 2A is formed so that a downstream side part 72 of the installing part of the valve guide 13 becomes larger in the upstream part 72a, and the downstream part 72b becomes smaller than the upstream side part 71 of the installing part of the valve guide 13. An inclination of a lower wall 7b of the intake port 7 to the cylinder axis 2B is formed so that the downstream side part 72 becomes larger than the upstream side part 71 of the installing part of the valve guide 13. The intake port 7 is formed so that the effective passage area of the intake port 7 in the downstream side part 72 of the installing part of the valve guide 13 becomes larger than the upstream side part 71. <P>COPYRIGHT: (C)2004,JPO |
