Inlet swirl throttle for passenger car engines

Abstract

The optimization of the boosting system plays a significant role in the evolution of gasoline and diesel engine towards increased fuel efficiency and reduced emissions.

Based on considerations to improve the functionality of boosting systems on diesel engines, intake throttling for low pressure exhaust gas recirculation (LP-EGR) enhancement and pre-swirl creation for the turbocharger compressor were combined in a newly designed component. This new device, the Inlet Swirl Throttle (IST) is located at the compressor inlet in the intake duct upstream the LP-EGR introduction. By closing the valve vanes, a pressure loss and a swirl motion are generated simultaneously. The swirl motion of the IST outlet flow field impacts the boosting performance while the variable pressure drop influences the driving pressure difference for the exhaust gas in the LP-EGR loop. A pre-swirl flow upstream the compressor can widen compressor maps and increase compressor efficiencies. When applying LP-EGR, compressor efficiency is increased by improved mixing of the recirculated exhaust gas and fresh air.

Extensive engine and turbocharger test bench investigations were carried out to quantify the performance benefits for the turbocharger and the overall engine in steady state operation. An EGR operation strategy was implemented and used for transient engine tests.