Analysis of Drivability Influence on Tailpipe Emissions by Means of Engine-in-the-Loop Test Benches 2020-01-0373
Due to increasing environmental awareness, standards for pollutant and CO2 emission legislations are getting stricter in most markets around the world. In important markets such as Europe, also the emissions during driving on real roads, the so called “Real Driving Emissions” (RDE), are now a part of the type approval process for passenger cars. In addition to the hybridization and electrification of vehicles, the complexity and degrees of freedom of conventional powertrains with internal combustion engines are continuing to increase in order to comply with stricter exhaust emission standards. Besides the different requirements placed on vehicle emissions, the drivability capabilities of passenger vehicles desired by the costumers, varies within markets. Since the interactions between different hardware and software systems of the powertrain strongly influence the drivability characteristics of a vehicle, a high degree of maturity of prototype vehicles is required to execute drivability calibration tasks. Hence, these tasks are generally conducted in late phases of the vehicle development process. The assessment of the influence of drivability calibration on the vehicle’s tailpipe emissions is complex. Since any changes to the powertrain, except calibration changes, are very expensive in late development phases, drivability related emission analyses are usually not specifically carried out.
Before this backdrop, this article introduces a method to determine the influence of drivability calibration on tailpipe emissions during early vehicle development phases. The utilization of objectified approaches for the analysis of the drivability behavior of passenger vehicles enables frontloading of drivability calibration tasks into phases of investigations on engine test benches. Thereto, a highly dynamic “Engine-in-the-Loop” (EiL) test bench, which is equipped with emission analyzers and operated as part of a virtual co-simulation scenario, is used to compare the individual emissions of two regional different drivability calibration data sets for the same powertrain. The obtained results are compared to the emissions of a real vehicle with the same calibration data sets. Using this method, the customer and market-specific requirements for longitudinal drivability and their interdependencies on the vehicle’s tailpipe emissions can already be considered in early vehicle development phases, in which real vehicles are not yet available. Thus, the risk of expensive late changes during a development program can significantly be reduced.
Christian Heusch, Daniel Guse, Frank Dorscheidt, Johannes Claßen, Timm Fahrbach, Stefan Pischinger, Stefan Tegelkamp, Michael Görgen, Martin Nijs, Johannes Scharf
RWTH Aachen University, FEV Europe GmbH