Intake Valve Lift Strategies for an Unthrottled Engine at Low Load Conditions

摘要

The selection of an optimum strategy at a low load condition has to be a compromise between the fuel economy and the combustion quality. If the combustion stability for an unthrottled engine is determined not to be degraded from the throttled engine, the best lift strategy should be the one that satisfies the combustion stability requirement at the same time has the biggest improvement of the fuel economy. In addition, a very carefully designed valve control system is needed to reduce the variations in valve lift and duration for the purpose of smooth combustion.