Oil ring for internal combustion engine and piston assembly including the same

An oil ring for an internal combustion engine, mounted in a ring groove formed in a piston assembly and having an outer peripheral surface slidably coupled to a cylinder inner wall, the oil ring for an internal combustion engine comprising:

• a ring-shaped body;
• a compression portion protruding from an upper portion of the body and in close contact with the cylinder inner wall;
• a scraper portion protruding from a lower portion of the body and in close contact with the cylinder inner wall;
• an oil suction portion being a space formed between the compression portion and the scraper portion to collect and discharge oil into the body;
• and
• a wear-resistant reinforcement layer formed on the outer peripheral surface of the oil ring for an internal combustion engine, the outer peripheral surface being slidably coupled to the cylinder inner wall;
• wherein the compression portion includes:
• a compression portion outer peripheral surface in close contact with and slidably coupled to the cylinder inner wall for facing toward a cylinder liner;
• a compression portion first surface connected to an upper portion of the compression portion outer peripheral surface for facing toward a combustion chamber;
• a compression portion second surface connected to a lower portion of the compression portion outer peripheral surface for facing toward a crankcase;
• and
• a compression portion curved portion formed at a connection portion of the compression portion first surface and the compression portion outer peripheral surface and having a predetermined curve, and
• the compression portion curved portion has a thickness smaller than that of the wear-resistant reinforcement layer to be formed in a region where the wear-resistant reinforcement layer is formed.