F2008-06-053
Active Air Management with Air Pulse Valve - Strategies to Overcome Emission Legislations for DI-Diesel-Engines
The modern diesel engine is considered worldwide as a power plant which combines performance and efficiency. In Western Europe, diesel powered cars have already reached a market-share of about 46% and the customers demand is still increasing. However stringent emission regulations constrain the manufacturers and research institutes to break new grounds. In addition to a further optimization of combustion chamber geometry and injection systems, new concepts to influence and control the gas-exchange-process and intake air composition have to be examined. Beside variable valve train systems, which cannot be easily realized at HSDI Diesel engines, an impulse charging device presents a low cost alternative. The paper shows potentials of a high speed flap upstream the intake valve, to control the amount of fresh mixture and its composition. With this switching device not only impulse charging or miller-cycle are enabled but, also a new kind of external EGR. The following potentials are represented in detail: - Dynamic Impulse Charging, which offers new levels of a spontaneous torque increase from cycle to cycle, - Miller-Cycle with and without air mass compensation, to open new ways in NOx-reduction and to break up the PM-NOx-Trade Off, - Cyclic External EGR, hereby it is possible to control the amount of cooled external EGR from cycle to cycle. The combination of effects will show both benefits for conventional DI-Diesel combustion processes and new degrees of freedom for Diesel - HCCI - Combustion.
Session: Charging Systems