Measures to fulfill “real driving emission (RDE)” with Diesel passenger cars

Passenger car manufacturers are currently facing the task of controlling the real-driving emissions of cars on public roads in spite of highly varying driving conditions to such an extent that these emissions deviate only little or not at all from the emissions established during standardized type approval testing. The legislation on real-driving emissions (RDE) primarily aims at the particle count and nitrogen emissions. The widespread use of particle filters in modern diesel cars has already brought particle emissions produced during combustion down to an extremely low level; however, effectively limiting nitrogen emissions is in focus. The Diesel Systems division of Robert Bosch GmbH is carrying out comprehensive studies in order to define technical measures that can support manufacturers by effectively limiting the real-driving emissions. Since these studies had not been completed yet when this paper was written, some of the results presented on the following pages are preliminary and may get updated during the actual presentation. As the authors of this paper wish to present the most up-to-date results during their presentation, they kindly ask for readers’ understanding for this procedure. The results of the studies, some of which are presented in this paper, indicate that the RDE requirements can be met through an intelligent combination of measures optimizing the engine and the exhaust gas aftertreatment system – without negatively impacting fuel consumption and driving performance. While the paper presented at the 2016 Stuttgart Symposium /1/ had focused on engine-related measures on the air system, this paper will primarily deal with temperature management of the engine and exhaust systems. Mild electrification, which is to be expected due to the lowered CO2 fleet emission limits applicable as of 2020, can contribute to meeting the emission targets but does not represent an indispensable prerequisite to meet nitrogen oxide targets.