Utilizing low airflow strategies, including cylinder deactivation, to improve fuel efficiency and aftertreatment thermal management

Abstract

Approximately 30% of the fuel consumed during typical heavy-duty vehicle operation occurs at elevated speeds with low-to-moderate loads below 6.5 bar brake mean effective pressure. The fuel economy and aftertreatment thermal management of the engine at these conditions can be improved using conventional means as well as cylinder deactivation and intake valve closure modulation. Airflow reductions result in higher exhaust gas temperatures, which are beneficial for aftertreatment thermal management, and reduced pumping work, which improves fuel efficiency. Airflow reductions can be achieved through a reduction of displaced cylinder volume by using cylinder deactivation and through reduction of volumetric efficiency by using intake valve closure modulation. This paper shows that, depending on load, cylinder deactivation and intake valve closure modulation can be used to reduce the fuel consumption between 5% and 25%, increase the rate of warm-up of aftertreatment, maintain higher temperatures, or achieve active diesel particulate filter regeneration without requiring dosing of the diesel oxidation catalyst.