| 摘要 |
<P>PROBLEM TO BE SOLVED: To make pressing force of a piston ring against a cylinder inner circumference surface suitable. Ž<P>SOLUTION: An inner diameter of a cylinder inner circumference surface 2a is formed in a shape gradually reducing as it further leaves from a combustion chamber. Consequently, since a piston ring expands in a piston rise stroke, reduction range of pressing force against the cylinder inner circumference surface becomes large in a first piston ring 21 having higher spring constant than that of a second piston ring 22, it is inhibited that large back pressure acts due to wraparound of combustion pressure and the pressing force gets excessive, and oil film formation at an outer circumference of the first piston ring is secured. Consequently, seizure and friction in a piston ring structure can be reduced. Since a spring constant is relatively low in a second piston ring, drop of pressing force is small even if the same expands in a rise stroke, drop of oil scratch off property can be inhibited, and appropriate oil collection can be secured. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
|
