A Dynamic Theory of Piston-Ring Lubrication : 1st Report. Calculation

Abstract

Near the T.D.C. of the expansion stroke of the engine, the piston-ring speed is 0 and its load and temperature reach a maximum. If it were based ob the steady-flowhydrodynamics, the oil film between the ring and the cylinder would have to be broken down. In practice, however, the fluid-film lubrication is achieved in the high speed region. These phenomena can be explained by a dynamical theory of the hydrodynamics, the piston-ring speed and load vary so extremely that the oil-film thickness changes rapidly, and this rate of change in the oil-film thickness generates a load carrying capacity by the squeeze action. This paper introduces the equations of the above-mentioned theory, and some calculations are carried out for a ring, the surface profile of which consists of the quadratic and the parallel line.