Extended cylinder deactivation strategies to improve CO₂ and pollutant emissions for light-duty diesel engine applications

Zusammenfassung

Further improvement of the trade-off between CO₂- and pollutant emissions motivates the development of new diesel engine concepts. The deactivation of one or more cylinders of a light-duty diesel engine during low load operation can be a sophisticated method to improve fuel economy and reduce especially NO_X emissions at the same time.

This publication presents the potential of extended cylinder deactivation (CDA) strategies by means of steady-state, 1D simulations in combination with transient powertrain simulations. The transient cycle investigations have been conducted using the Worldwide Harmonized Light Vehicle Test Procedure (WLTP) and Real Driving Emissions (RDE) cycles. A representative mid-size SUV, powered by a state-of-the-art 2.0 l, 4-cylinder diesel engine, was considered for these investigations. The engine is equipped with both high and low pressure EGR and a closed-coupled DOC/SCRF system with an additional underfloor SCR.

The potential of a selective CDA of separate cylinders by Dynamic Skip Fire (DSF®) technology, as part of an extended CDA strategy, has been analyzed in detail. The results show a CO₂-benefit of approximately 2 % under a RDE cycle, while simultaneously reducing tailpipe NO_X emissions by approximately 11 %. These improvements have been achieved by an increased engine efficiency due to a shift in the engine operation conditions by the extended CDA strategies. Implementing these CDA strategies also results in higher exhaust temperatures which further improves the conversion efficiency of the aftertreatment system. Furthermore, the investigations have been extended to show the potential of this strategy when applied to an 8.0 l medium duty diesel engine application.