On the Oil Film Behaviour of Piston Rings : Correction of Effective Pressure Region of Oil Film

Abstract

This paper reports on a theoretical calculating procedure of the oil film behaviour between the piston ring and the cylinder wall. The analysis assumes: (1) that the sliding surface of the ring may be approximated by a parabola; (2) that the oil film viscosity is constant; and (3) that the trailing end of oil film pressure varies according to the Reynolds boundary condition, namely the pressure profile ends at apposition where the pressure becomes a downstream pressure and also the pressure gradient becomes zero. The paper gives also an example of oil film behaviour between the circular-faced piston ring and the cylinder wall which has been calculated under the conditions corresponding to a small sized 4-stroke cycle kerosene engine.