Evolution of a Lean SPCCI Engine by Millerization and Electric Turbocharging

Authors

Dr.-Ing. N. Al-Hasan, Dipl.-Ing. J. Simader, Dipl.-Ing. (FH) S. Nibler, BMTS Technology GmbH & Co. KG, Stuttgart; Dipl.-Ing. A. Mayer, Dipl.-Ing. P. Müller, D. Hain MSc, Schaeffler Technologies AG & Co. KG, Herzogenaurach:

Year

2022

Print Info

Production/Publication ÖVK

Summary

It is a global requirement to improve the efficiency of combustion engines in order to reduce fossil or non-fossil fuel consumption. Current technologies for fuel consumption reduction are hybridization and mild Millerization in combination with geometric compression ratio increase and engine downsizing.

Mazda introduced the “Spark Controlled Compression Ignition" SPCCI technology into the market with the Skyactiv-X engine. The new combustion concept enables an efficiency increase by lean combustion in restricted areas and a very high compression ratio CR = 16.3.

Cooled external exhaust gas recirculation (EGR) and mechanic supercharging increase the efficiency further while the power density is only slightly above naturally aspirated engines. In this paper, a combination of an electrically assisted VTG-turbocharger and a variable valve train is used to further increase efficiency and performance as follows:

At full load, a higher charge pressure in combination with a significant Miller degree mitigates knock, resulting in an improved combustion phasing, and a higher specific torque and power while omitting enrichment.

The variable valve train guarantees an optimal effective compression ratio with a specific volumetric efficiency for each operating point to improve the center of combustion and to ensure a stable SPCCI combustion. As a result, the load map area with high efficiency is enlarged. Furthermore, the use of exhaust enthalpy by the turbocharger helps to increase the net engine efficiency.

ISBN

1920-2323-23-1

Number of pages

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