OIL RING FOR INTERNAL COMBUSTION ENGINE

摘要

An object of this invention is to provide an internal combustion engine oil ring which stably retains, for a long period, the function of scraping excess oil from a cylinder inner wall surface and letting the excess oil flow down to an underside of a piston and ensures reduction in the amount of oil consumption when an internal combustion engine is driven. In order to achieve the object, there is adopted an internal combustion engine oil ring, wherein an oil ring main body includes, along an inner peripheral surface, a coil expander receiving recess having a generally semicircular shape in cross-section in an oil ring axial direction, an inner peripheral surface of the coil expander receiving recess has an oil return groove formed along an inner peripheral direction for smoothly returning scraped oil to an underside of a piston, and an outer peripheral shape of the oil return groove is composed of a straight line and a curved line continuous with the straight line in cross-section in the oil ring axial direction.