Vacuum management system for engine with variable valve lift

摘要

A vacuum management system for an engine with variable valve lift includes a vacuum control valve at the entrance to the intake manifold to increase vacuum within the manifold as needed and preferably only when it can be done without impairing fuel economy or engine performance. Vacuum may then be used for any of various vacuum-assisted devices and functions, for example, boosting a vehicle braking system. The numerical relationships among important operating parameters are determined in a laboratory, and a programmable engine control module (ECM} is provided with algorithms and tables of such values by which the ECM is able to vary valve lift and vacuum control valve position to provide optimum flow across the intake valves and optimum manifold vacuum under all engine operating conditions.