| 摘要 |
PURPOSE:To provide an oil-scraping-off function as well as a carbone-scraping- out function, by a method wherein, in a scraper ring of a piston, a toroidal concave portion is formed in a central portion of an external circumference surface of a ring making contact with a cylinder wall surface. CONSTITUTION:A scraper ring 10, which is mounted at an upwardmost portion of a piston in an engine, has an operation necessary to scrape out carbon adhered to a cylinder wall surface 12. A groove 11 having the shape of an arc of a circle in a cross section is formed along an outer circumference surface of the scraper ring 10 at a central portion thereof, and this causes the formation of upper and lower contact surface 13 and 14 which make contact with the cylinder wall surface 12. Said contact surface 13 and 14 are positioned so that they make contact with contact points 13a and 14a at an angle of 90 deg. or at an acute angle of below 90 deg.. A cross section of the ring 10 is formed in a wedge shape with an upper and a lower surface so that an inner diameter portion becomes thinner. A vertical slit for ventilation is made in an outer circumference of the ring 10. |
