Development and Application of Ring-Pack Model Integrating Global and Local Processes. Part 2: Ring-Liner Lubrication

A new ring pack model has been developed based on the curved beam finite element method. This paper describes the second part of this model: simulating oil transport around the ring pack system (two compression rings and one twin-land oil control ring (TLOCR)) through the ring-liner interfaces by solving the oil film thickness on the liner. The ring dynamics model in Part 1 calculates the inter-ring gas pressure and the ring dynamic twist which are used in the ring-liner lubrication model as boundary conditions. Therefore, only in-plane conformability is calculated to obtain the oil film thickness on the liner. Both global process, namely, the structural response of the rings to bore distortion and piston tilt, and local processes, namely, bridging and oil-lube interaction, are considered. The model was applied to a passenger car engine. It was found that a net oil scraping by the top ring, as a potential oil consumption source, only occurs with a combination of high bore distortion and local oil bridging. The effect of fuel deposition on the oil film was also investigated.