Abstract
Keywords -Active Air Management; Air Pulse Valve; Impulse Charging; Miller-Cycle; Exhaust Gas Recirculation
In the last two decades, the diesel engine has found its booming way into the European passenger car motorization. This is due to the implementation of direct injection technologies and turbocharging, which drastically enhanced the dynamic behaviour and the efficiency. To overcome the future emission legislations will be a requirement for a further propagation of passenger car diesel engines. At the same time, the diesel engine has to keep its fuel consumption benefit or to improve it.
To fulfil these requirements, exhaust aftertreatment strategies and above all, techniques of incylinder raw emission reduction have to be improved. Besides further developments of injection systems (pressures > 2000bar) and implementation of closed-loop control of cylinder pressure, it is essential to regulate also the cylinder charge with highest precision and dynamic. This requires systems that exhibit the dynamic for a cycle- and cylinder-selective intervention in the gas exchange process of a diesel engine. One approach, which is currently under investigation, is the camless Variable Valve Train (VVT). In addition to the high costs of such a system, the risk of a malfunction due to a piston-valve-collision militates against its introduction into series production.
A different approach for an active air management is the use of an Air Pulse Valve (APV) - a high speed flap positioned upstream of the intake valve. Because of its independent and highly dynamic electrical actuation, this system offers similar potentials like a camless intake VVT. Besides a brief overview about applications of an APV, this work shows experimental results of strategies that help to reduce fuel consumption and pollutant emissions of diesel engines. These strategies are impulse charging and different modes of Miller-Cycle.