Piston assembly for an internal combustion engine

摘要

A mechanism for sealing gaps between a piston assembly and a cylinder for an internal combustion engine is provided. A sealing member inserted into an upper wall of a groove holding the oil ring to block a gap between them. The oil ring has two rails on its outer periphery. The upper rail is radially bigger than the lower rail and conforms better to the shape of the cylinder. The oil ring has a recess on its inner periphery to hold a pressing member that forces the oil ring against the cylinder. The recess is extended beyond the pressing member to provide a larger contact area between the oil ring and the groove.