Practical challenges in determining piston ring friction

Abstract

Practical challenges from both experiment and calculation sides were discussed for determining two piece twin land oil control ring friction. A floating liner engine was used for twin land oil control ring study. Effects of floating liner engine system dynamics and piston skirt friction were addressed and methods to mitigate them were discussed. A deterministic twin land oil control ring model was used for ring friction calculation. Variation of the surface roughness at different spots of the liner and its effects on both hydrodynamic and boundary lubrication predictions were discussed. A multi-point correlation method was introduced to address surface variation effects on the twin land oil control ring model. Ring land width variation between two lands as well as along the circumference and its effects on calculation were shown, and methods to address it were discussed. By taking all these necessary steps in both experiments and calculations, this study shows that a reasonable match can be achieved between the measured and calculated friction, which covers all three lubrication regimes. This study lays a foundation for realistically predicting the friction of piston rings in internal combustion engines.