Variable Turbine Geometry – Evaluation of a Charging Concept for Future High-Efficieny Gasoline Engines

Authors

Dr.-Ing. M. Kluin, Dr.-Ing. C. Glahn, Dr.-Ing. I. Hermann, Dipl.-Ing. A. Königstein, GM Global Propulsion Systems Europe, Rüsselsheim

Year

2017

Print Info

Fortschritt-Berichte VDI, Series 12, No 802

Summary

Future combustion processes are placing increasing demands with regard to charge air pressure availability on the charging system of gasoline engines. The trade-off between high low-end torque with fast transient response and low turbine pressure ratios for high engine efficiency is therefore becoming critical. Variable turbine geometry (VTG) is a familiar solution to this issue. Although the technology has been state-of-the art on diesel engines for decades, VTG has not yet been established in the gasoline mass market due to the challenges related to the higher exhaust gas temperature and system costs. Nevertheless, high-efficiency gasoline combustion concepts like the Miller cycle have recently shown the strong benefits of VTG technology on gasoline engines with low specific output and low exhaust gas temperature below 900°C. Nevertheless, new designs and new material developments now enable the beneficial application of this technology on engines with higher outputs (> 90 kW/l) and exhaust gas temperatures up to 980°C, even for cost sensitive high volume markets. This paper describes the VTG turbocharging concept on a state-of-the-art 1.6L SIDI turbo engine and evaluates the technology’s potential regarding efficiency, transient response and drivability.