The forthcoming EURO-7 legislation, along with its strict NOx emission limits and further reduction of CO2 fleet target values, requires additional development steps, especially for heavy-duty Diesel. To cope with these new challenges, the exhaust gas temperature management will play a pivotal role. Facilitating short warm-up phases of the exhaust gas after treatment system, as well as keeping engine-out emissions at a minimum will be part of the major engineering tasks in the heavy-duty Diesel engine sector. In addition, unwanted cool-down of the exhaust after treatment system during the drive cycles needs to be avoided. In low load conditions, in particular, this conflicts with the need to minimize CO2 emissions.
Against this background, Schaeffler investigated the potential of fully variable valve lift & timing on a heavy-duty in-line six-cylinder engine, in comparison to alternative concepts like exhaust cam phasing or electrical catalyst heating.
In addition, the study assesses the potential of Schaeffler’s valve train solutions to support Zero-Impact engine concepts, including a virtual transition of a state-of-the art heavy-duty Diesel engine to a hydrogen powered SI engine.
The study suggests that fully variable intake valve train systems are an effective tool to meet future highly challenging emission targets and efficiency goals for ICEs. Moreover, adding flexibility to the exhaust valve timing paves the way for additional features like cylinder deactivation and compression release brake mode.
