MEASUREMENT OF OIL FILM THICKNESS BETWEEN INNER PERIPHERAL SURFACE OF CYLINDER AND OUTER PERIPHERAL SURFACE OF PISTON RING

摘要

PURPOSE:To accurately measure the thickness of a thin oil film, in performing measurement according to an electric capacity method, by using pick-up electrode having an insulating coating on the surface thereof. CONSTITUTION:A groove 2 is provided to the outer peripheral surface of a piston ring 1 by engraving and a pick-up electrode 5 having an insulating coating 4 provided to the surface thereof is mounted to and inlaid with the groove 2. The measured value with respect to electric capacity detected by thus formed electrode 5 is displayed by an oscillograph 9. From the reading of this oscillograph 9, the thickness of the oil film between the inner peripheral surface of a cylinder and the outer peripheral surface of the piston ring 1 is obtained. As mentioned above, because the pick-up electrode having the insulating coating applied to the surface thereof is used, the thickness of the thin oil film conventionally difficult in measurement can be accurately measured.