DYNAMIC BEHAVIOR OF OIL FILM BETWEEN PISTON-RING AND CYLINDER LINER (VISUALIZATION OF OIL FILM RUPTURE AND MEASUREMENT OF OIL FILM PRESSUREUSING SIMULATING RIG)

In order to clarify the behavior of oil film between a piston ring and cylinder liner, pressure measurement and visualization of oil film ar e carried out simultaneously using a simulation rig. In this rig, the piston ring is simulated by a straight glass bar test piece and the cy linder by a reciprocating flat plate. The following observations were obtained. The oil film pressure of the full film region before oil fil m rupture is negative and the maximum magnitude of negative pressure, i.e., tension, reaches to 0.35 MPa. Cavities are formed at 20 degrees- 30 degrees crank angle from dead center in the full film region, and g row with the increase of the crank angle. Then a new series of cavitie s is formed at the rear edge of the test piece. The two series of cavi ties then coalesce and the flow becomes perturbed momentarily. Negativ e pressure is detected at a 20 degrees-30 degrees crank angle after de ad center and is not released until this coalescence of cavities has o ccurred.