Search Results

The future worldwide emission regulations will request a drastic decrease of Diesel engine tailpipe emissions. Depending on the planned application and the real official regulations, a further strong decrease of engine out emissions is necessary, even though the utilized exhaust after-treatment systems are very powerful. To reduce NOx emissions internally, the external exhaust gas recirculation (EGR) is known as the most effective way. Due to the continuously increasing requirements regarding specific power, dynamic behavior and low emissions, future air path systems have to fulfill higher requirements and, consequently, become more and more complex, e.g. arrangements with a 2-stage turbo charging or 2-stage EGR system with different stages of cooling performance.

The continuously strengthened requirements regarding air quality and pollutant reduction as well as GHG emissions further complicate the compliance with legal standards. Especially in view of cost-sensitive applications this demand strongly collides with the EMS set-up and the sensor requirements with still increasing overall system complexity. The paper in hand describes a novel air path control approach, which offers the potential for a flexible use of multiple EGR routes to meet upcoming legislations more robustly, while providing a significant reduction of calibration effort and sensor content at the same time. By using a direct emission based cylinder charge control, also alterations in operational ambient conditions are covered with system reactions according to physical-based rules to enhance the engine-out emission performance without need for tuning of corrections of any air path set point.

Dynamic skip fire (DSF) is an advanced cylinder deactivation technology where the decision to fire or skip a singular cylinder of a multi-cylinder engine is made immediately prior to each firing opportunity. A DSF-equipped engine features the ability to selectively deactivate cylinders on a cylinder event-by-event basis in order to match the requested torque demand at optimum fuel efficiency while maintaining acceptable noise, vibration and harshness (NVH). Dynamic Skip Fire (DSF) has already shown significant fuel economy improvements for throttled spark-ignition engines. This paper explores the potential benefits of DSF technology in improving fuel economy while maintaining ultra-low tailpipe emissions for light-duty (LD) Diesel powertrains.