Architecture of a Detailed Three Dimensional Piston Ring Model 2011-24-0159

Piston rings are faced with a broad range of demands like optimal sealing properties, wear properties and reliability. Even more challenging boundary conditions must be met when latest developments in the fields of direct injection as well as the application of bio fuels.

This complex variety of piston ring design requirements leads to the need of a comprehensive simulation model in order to support the development in the early design phase prior to testing.

The simulation model must be able to provide classical objectives like friction analysis, wear rate and blow-by. Furthermore, it must include an adequate oil consumption model.

The objective of this work is to provide such a simulation model that is embedded in the commercial MBS software ‘FEV Virtual Engine’. The MBS model consists of a cranktrain assembly with a rigid piston that contains flexible piston rings. The interaction of the piston rings with the liner surface is modelled via a hydrodynamic mixed friction approach for rough surfaces. From this contact model the wear of the individual rings as well as that of the liner surface is provided. The gas interactions are included by a so called gas labyrinth model. Finally, an oil film distribution model is included that allows the calculation of the oil consumption tendency. It even allows the modelling of oil dilution by fuels in case of DI engines.

Parameter studies are made to show whether the specific models for ring pretension, HD-contact, friction and wear work properly.

The paper closes with an assessment of the quality of the results and gives an outlook to further development steps.