Oil Leakage and Friction Forces of Reciprocating O-Ring Seals Considering Cavitation

Abstract

This paper deals with the problem of calculating oil film thicknesses, oil leakage, and friction forces in seal situations like those occurring in hydraulic cylinders. A general scheme for the analysis is presented, covering both piston seals and piston rod seals. The theoretical model considers influence both from the seal itself and from surrounding parallel clearances. It also takes cavitation into account when this occurs. The validity of the model is limited to cases with well lubricated seal contacts, i.e., unbroken oil films. The analysis follows the inverse hydrodynamic theory and requires a known pressure distribution for each seal element. The pressure distributions are calculated with a method presented earlier by the author (at the 5th Leeds-Lyon Symposium on Tribology, September 1978). Calculated values of oil film thicknesses, leakage flows and friction forces are presented for different sealed pressures and different sliding velocities.