A Theoretical Analysis of the Twin-Land Type of Oil-Control Piston Ring

Abstract

Cyclic variations of the important operating characteristics of the twin-land type of oil-control ring have been analysed by considering radial and torsional equilibrium of the ring cross-section. The assumed form of the face profiles of the lands are related to measurements of worn oil-control rings and the analysis includes the effect of surface roughness in the mixed lubrication regime. The results show that oil-control rings may operate with fluid film, mixed, or boundary lubrication, depending upon the land profiles, the attitude of the ring, and the surface roughnesses on liners and rings. A small height difference between the lands is shown to have a significant effect upon the calculated volume of lubricant passing the ring and the analysis has provided the basis for further rational design of this important machine element.