Method for transitioning between a controlled auto-ignition mode and a spark-ignition mode for direct fuel injection engines

摘要

A method for controlling the transition between combustion modes of a direct injection engine that is operable at lower loads in a mode of compression ignition with homogeneous charge (HCCI) and at higher loads in a mode of spark ignition flame propagation (SI), the engine a system with variable valve actuation including two-stage high and low lift valve actuation and separate cam timing for both intake and exhaust valves, the method comprising: operating the engine in a steady state with fuel-air-exhaust mixtures at For each speed and load specified states of the fuel supply mass flow (the fuel supply rate), the injection timing (FI), the ignition timing (SI), the throttle valve position, the exhaust gas recirculation (EGR) valve setting and the negative valve overlap (NVO) between recompression obtained by closing the exhaust valves and opening the intake valves in each cylinder; and controlling the engine during mode changes between the HCCI mode and the SI mode by switching the exhaust and intake valves between a low lift for the HCCI operation and a high lift for the SI operation, ...