The main challenge for passenger car diesel engines in Europe is fuel consumption reduction to reach EU legislative targets by 2020. For US applications the target is to meet the upcoming LEV-III emission legislation. Combined with valve seat swirl chamfers on the intake side, variable valvelift allows a very efficient swirl increase, as pumping losses are considerably reduced compared to a port deactivation concept. And the charge motion becomes more homogeneous, providing further emission benefits. Variable valve timing enables internal exhaust gas recircu-lation (EGR), supporting combustion under adverse conditions such as operation with high charge dilution. It can also be used to increase exhaust gas temperature, allowing filter regeneration even during frequent short-distance driving under cold conditions.
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