PISTON RING AND ENGINE

摘要

Provided is a piston ring on which a membranous carbon film is formed with good productivity on the external peripheral sliding surface and the top and bottom surfaces, the carbon film being optimized so as to be adapted to the performance required by the surfaces; also provided is a high-performance engine in which such a piston ring is used. In this piston ring, in which a carbon film is formed on the external peripheral sliding surface and the top and bottom surfaces, the carbon film contains a stacking of at least two types of carbon film layers having different membranous properties, and the layer thickness ratio of the two types of carbon film layers is different between the external peripheral sliding surface and the top and bottom surfaces. The carbon film is formed by stacking a first carbon film layer formed on a piston ring body side and a second carbon film layer formed on a front surface side, the thickness of the second carbon film layer in the top and bottom surfaces is less than the thickness of the second carbon film layer in the external peripheral sliding surface, and the ratio of the thickness of the second carbon film layer to the thickness of the first carbon film layer is greater in the external peripheral sliding surface than in the top and bottom surfaces.