Integrated engine dilution control

摘要

The method controls dilution of intake air passing through an intake manifold of an IC engine (10) having a variable valve timing control device for controlling internal dilution by controlling the relative timing of engine cylinder intake and exhaust valve events and having an EGR control device for controlling external dilution by controlling recirculation of engine cylinder exhaust gasses through an EGR conduit. The method involves storing a calibrated model of a relationship between predetermined dilution control parameters, and sensing presence of a predetermined operating condition when dilution of the intake air is required. Dilution is controlled when the predetermined operating condition is present, by generating a desired dilution value, and calculating a desired intake manifold air pressure as a predetermined function of the desired dilution value. A valve timing command is generated as a function of the desired intake manifold air pressure as the valve timing command providing internal dilution sufficient to drive intake manifold air pressure toward the desired pressure. Internal dilution is controlled by regulating relative timing of engine cylinder intake and exhaust valve events in accord with the valve timing command.