The laws for adhering to exhaust emissions during real-life driving (RDE = Real Driving Emissions) affect the entire engine development process. Our many years of experience in application, engine and drivetrain development help us provide our customers with optimum support regarding RDE. Depending on the problem, RDE investigations can be conducted on the dynamic engine test bench, on the roller dynamometer or in real-life road traffic. In the same way, the simulation can be used to evaluate different engine concepts under RDE boundary conditions very early on.
For each driving profile complying with the criteria of the RDE legal requirements, the specified exhaust emissions must be adhered to while taking into account a “conformity factor”. The result: an “average”, typical RDE driving profile is not particularly interesting. Rather, it is under the least favorable test which still just falls within the RDE criteria where the exhaust aftertreatment must function. This most unfavorable RDE profile can look different for each combination of engine, exhaust treatment and drivetrain.
In certain circumstances, critical driving profiles cannot always be reproduced in real traffic, especially concerning a combination of a stop-and-go traffic jam situation, a potentially cooling-off exhaust aftertreatment system and subsequent acceleration on a main road or motorway.
Critical situations can be identified early on using traffic and route simulations combined with FKFS’ years of experience with volunteer studies and driver behavior. And, in certain circumstances, a long descent (while adhering to the RDE criteria) from the Black Forest into the Rhein Valley with the engine in coasting mode can be more critical than the stop and go situation described above.
The effect on RDE-conformity must be considered early on in the concept phase of engine development, as well as when evaluating technologies from suppliers. To do this, either a flow model of a real engine can be used, or one of the models from our virtual engine construction kit.
As well as rendering real test vehicles / prototypes unnecessary, virtual RDE has the great advantage that more than a hundred virtual drivers can be tested on different routes in a manageable time. The virtual driver can be based on the behavior of real drivers in vehicle trials.
In virtual RDE, direct, quantitative evaluation of emissions is often not sufficiently reliable. However, exhaust and catalytic converter temperatures can be predicted very well. These then serve as indicators for an operation-ready exhaust aftertreatment system.
The excellent traffic connections and our location on the edge of Stuttgart give FKFS direct access to city streets, highways and motorways. The measurement runs can be combined with close by descents and inclines. We have an application hall with workshop equipment for housing test vehicles and equipping them with PEMS (Portable Emission Measurement Systems), plus a roller dynamometer test bench for simulations.
RDE on the Dynamic Engine Test Bench
RDE measurement runs on the road do not always offer the chance to bring the vehicle drive into the critical states needed for compliance with the limit values/to approach the limit regions. So it makes sense to run the vehicle drive on the engine test bench, with a simulation of the vehicle and the environmental conditions. In this way, consumption and emissions can be recorded without having to make any compromises. With our modern test benches, FKFS offers the opportunity to study entire RDE runs or selected route sections under changing external influences.