Diesel engines belong to the most efficient power sources for any kind of on-road vehicle, but especially in Europe increasingly for passenger cars. However, more stringent exhaust emission regulations, which will come into force world-wide in industrialised countries during the first decade of the next century will require NOx and particulate emissions to be reduced by up to 60% and more from today's levels.
To meet these future emission standards particularly for heavier passenger vehicles, such as SUVs, Pickup Trucks and Light Commercial Vehicles, as well as for heavy luxury class passenger cars, the application of new technologies including advanced exhaust gas aftertreatment systems will be indispensable, especially in view of maintaining the thermal efficiency of diesel engines relative to gasoline engines.
The paper reports on the outcome of a still on-going joint-research project with the objective of establishing a demonstrator high speed direct injection (HSDI) diesel engine in a Sports Utility Vehicle (SUV) which allows to exploit the effectiveness of new engine and aftertreatment technologies for reducing exhaust emissions to the future levels of Euro 4 and Euro 5.
In general two different routes for meeting future standards are currently under discussion:
(1) reduce NOx by advanced engine technologies (cooled EGR, flexible high pressure common rail fuel injection system, adapted combustion system) and reduce particulates by a Diesel Particulate Filter (DPF) such as the Continuous Regeneration Trap (CRT™), and (2) reduce the particulate emission of the base engine, namely carbon derived particulates, by means of advanced engine technologies (flexible high pressure common rail fuel injection system, adapted combustion system) and reduce NOx further by a DeNOx aftertreatment technology.
The current paper presents engine and vehicle results of route (1). However, also route (2) is currently being investigated with success at the authors' company. Thus, at the end of the paper an outlook on a combination of both routes will be given which will be required for meeting the expected Euro 5 emission limits with this vehicle category.