| 摘要 |
A piston ring reduces reciprocating friction between a piston and an inner wall surface of a cylinder, while maintaining reduction effect of the reciprocating friction. The piston ring is mounted in a ring groove of the piston, and slides against the inner wall surface of a cylinder liner or a cylinder. The piston ring includes: plural fine recessed portions formed in a barrel width region on an outer peripheral sliding surface of the piston ring; and a non-recessed portion area where no recessed portions are formed in the barrel width region. The non-recessed portion area is configured to have an area percentage within a range from 20-85% in the barrel width region where an area percentage of the barrel width region before the recessed portions are formed is defined to be 100%. The non-recessed portion area exists through an entire cross section in an axial direction of the barrel width. |
