As modern diesel engines strive towards ever better low-end torque and high-end power, multi-stage turbocharging appears as a key enabling technology. Two key architectures (serial-sequential and parallel-sequential) were presented. The ever more stringent emission and fuel-consumption constraints, combined with continuously-reduced available space under the bonnet raise the question of the relevant architecture for larger engine displacements. A new 3.0L V6 engine drove the selection of a Parallel-sequential system to meet high torque at low-end, with optimum BSFC and emission performance, while meeting high power output. Key success parameters for more complex parallel-sequential systems are an optimised matching, good sealing capabilities, high reliability at high temperature, and most of all, very fine controllability. The development and qualification of a reliable, performing, high-temperature turbine control valve has been exposed. The associated compressor valve and control logics were also exposed. Performance of the latest parallel-sequential 2-stage system was compared with other mono-turbo and bi-turbo engines. While meeting similar or lower BSFC as the latter, the Parallel-sequential system achieved outstanding performances in terms of tow-end torque and high-end power, not mentioning transient response. With established attributes on larger displacement engines, parallel-sequential could be a clear path forward for high performance Passenger Vehicles and Light-Trucks. Smaller displacement engines, similarly to former releases, could benefit from such architecture: emission requirement might drive this, yet aerodynamics performance need to enable It. Yet, the question of engine affordability needs to be addressed as a global system, if multi-stage turbocharging is to become more popular.
Sequential boosting valve & Turbocharger system sets new standard for diesel V-engines
Aufladetechnische Konferenz, 14 ; 223-249
2009
27 Seiten, 28 Bilder, 3 Quellen
Aufsatz (Konferenz)
Englisch
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