Authors

P. Kapus, K. Prevedel, X. Yan, D. Trawöger, K. Stark, W. Schnider, AVL List GmbH, Graz; X. Gao, C. Gu, Z. Zhang, Y. Liu, X. Ju, Chery Group, Wuhu, China

Year

2026

Print Info

Production/Publication ÖVK

Summary

More stringent CO₂ emission targets and aggravated utility factors for weighing between all electric cycles and ICE supported cycles require on the one hand larger batteries to maintain attractive CO₂ certification values with Hybrids and Range Extender (REX) Vehicles. On the other hand, this also enhances the impact of ICE efficiency on the certified CO₂ emission number of Hybrid or REX vehicles. Ultra-high efficiency engines play a key role in the market competition, especially in China as part of the NEV (New Energy Vehicles) regulation. In Europe the cancellation of the ICE ban could lead to the revival of efficient engines.
This paper describes the use of a mechanical Atkinson cycle engine combined with aggressive Miller cycle realized by valve timing, high compression ratio, high external EGR rates and efficient boosting to achieve an overall best effective efficiency of 48% at stoichiometric combustion.

The mechanical Atkinson cycle is realized by a link mechanism combining a standard crankshaft and an Atkinson shaft rotating at half crankshaft speed. This mechanism allows an expansion ratio of 25,5:1 at a geometric compression ratio of 17:1.
Specific geometry results in reasonable forces and torque levels in the mechanism of a 4-cylinder engine.
The design, simulation and experimental engine results are described.

ISBN

978-3-9504969-5-6

DOI

https://doi.org/10.62626/thbk-p9fw Copy link

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