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A new ring pack model has been developed based on the curved beam finite element method. This paper describes the first part of this model: simulating gas pressure in different regions above piston skirt and ring dynamic behavior of two compression rings and a twin-land oil control ring. The model allows separate grid divisions to resolve ring structure dynamics, local force/pressure generation, and gas pressure distribution. Doing so enables the model to capture both global and local processes at their proper length scales. The effects of bore distortion, piston secondary motion, and groove distortion are considered. Gas flows, gas pressure distribution in the ring pack, and ring structural dynamics are coupled with ring-groove and ring-liner interactions, and an implicit scheme is employed to ensure numerical stability. The model is applied to a passenger car engine to demonstrate its ability to predict global and local effects on ring dynamics and oil transport.

The wear patterns of the rings and grooves of a diesel engine were analyzed by using a ring dynamics/gas flow model and a ring-pack oil film thickness model. The analysis focused primarily on the contact pressure distribution on the ring sides and grooves as well as on the contact location on the ring running surfaces. Analysis was performed for both new and worn ring/groove profiles. Calculated results are consistent with the measured wear patterns. The effects of groove tilt and static twist on the development of wear patterns on the ring sides, grooves, and ring running surfaces were studied. Ring flutter was observed from the calculation and its effect on oil transport was discussed. Up-scraping of the top ring was studied by considering ring dynamic twist and piston tilt. This work shows that the models used have potential for providing practical guidance to optimizing the ring pack and ring grooves to control wear and reduce oil consumption.

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.