Piston ring structural body and method of mounting the piston ring structural body

摘要

The present invention provides a piston ring structural body composed of an outer ring continuously formed of a resinous material, an inner ring continuously formed of a resinous material and a ring tensile force applying member for pressing the outer ring radially outwards via the inner ring. The piston ring structural body has a construction wherein the outer ring continuously formed of polyimide is pressed outwards in the radial direction of the piston by a coil expander via the inner ring continuously formed of PTFE. A sliding face of the outer ring, which slides on a cylinder wall, is divided into upper and lower sliding faces, whose respective upper edge portions are provided with chamfers. A contact portion of the inner ring that contacts the coil expander is provided with an upper inclined face extending inwards and upwards and a lower inclined face extending inwards and downwards. The angles of inclination of the upper and lower inclined faces range from 30° to 60°.