Innovative Piston Technologies for Future Efficiency and Emission Targets

Authors

Dipl.-Ing. Tobias Kaudewitz, Dipl.-Ing. Frank Lange, Dr.-Ing. Ralf Rablbauer, Dr.-Ing. Aiko Mork, Dipl.-Ing. Martin Schüttenhelm, Dipl.-Ing. Michael Frambourg, Dr.-Ing. Tobias Lösche-ter Horst, Volkswagen AG, Wolfsburg;
Prof. Dr.-Ing. Heinz Pitsch, RWTH Aachen University, Aachen

Summary

Compression ignited combustion engines contribute significantly to reduced fleet CO₂ emissions. Equipped with modern exhaust gas after treatment systems, they are simultaneously able to fulfill most challenging exhaust gas emission regulations. One key for further improvements is thermal optimization. Both fuel efficiency and exhaust gas temperature level can be increased by reducing wall heat losses. This leads simultaneously to lower CO₂ emissions and higher temperature levels which are needed for the usage of a modern exhaust gas emissions reduction system. Innovative piston technologies realizing those targets were investigated within Volkswagen Group Research. Due to intense cooperation between the fields of simulation, engine testing and material research a sophisticated system knowledge about heat transfer in internal combustion engines was developed. Using this process, thin thermal barrier coatings were optimized for a diesel combustion system, tested for durability and analyzed regarding their thermodynamic effects. The simulation methodology developed for this application, capable of resolving a transient and spatial temperature distribution, is a powerful tool defining optimized material properties. Thermal conductivity, volumetric heat capacity, coating thickness and surface structure are the key properties which influence the effect of the coating. This research campaign shows that further improvements of compression ignition engines are possible and forceful developments can lead to significant contributions to climate protection.

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