| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent uneven wear of an exhaust valve particularly subjected to severe uneven wear, and to reduce exchange frequency of the exhaust valve or a valve seat, in an internal combustion engine. <P>SOLUTION: A ratio between an exhaust valve element diameter a and a gap d between a cylinder inner surface 12a and an exhaust valve element 20b is set to 12%≤d/a≤27%. A ratio between a cylinder bore diameter b and a length c of a non-guide part upon the closure of an exhaust valve 20 positioned below a lower end of a sleeve 26 is set to 40%≤c/b≤50%. A ratio between a diameter S of an exhaust valve bar 20a and a gap e between the exhaust valve bar 20a and the sleeve 26 is set to 0.5%≤e/S≤0.8%. Thus, a nonuniform flow of combustion exhaust gas flow g formed at the periphery of the exhaust valve element 20b is eliminated by widening the gap d, shortening the length c of the non-guide part, and narrowing the gap e, and biased contact of the exhaust valve element 20b to a valve seat 24 is eliminated, thereby preventing uneven wear of the members. <P>COPYRIGHT: (C)2013,JPO&INPIT |
