Patent ID: 8863728

Claim:
Method for controlling a direct-injection internal combustion engine, comprising: monitoring internal combustion engine operational parameters including a monitored engine speed; determining a start of injection in response to the engine operational parameters; monitoring an intake air flow into the engine comprising a residual gas component and fresh air flow into an intake manifold of the engine; monitoring an exhaust gas flow into the intake manifold; monitoring a fuel flow into the engine; determining a steady-state in-cylinder residual gas fraction based upon the exhaust gas and fresh air flows into the intake manifold and the fuel flow into the engine; determining a time constant corresponding to an intake air flow reaction time based upon the intake air flow, the exhaust gas flow, engine speed, and the fuel flow; calculating an instantaneous in-cylinder residual gas fraction using the steady-state in-cylinder residual gas fraction and the time constant; modifying the start of injection based upon the calculated instantaneous in-cylinder residual gas fraction; and operating the engine subject to the modified start of injection.