SI - HCCI Mode Switching Optimization Using a Physics Based Model

High efficiency and low NOx emissions make Homogeneous Charge Compression Ignition (HCCI) promising for use in internal combustion engines. Combining HCCI with Spark Ignition (SI) allows for extension of the engine’s operating range.;A Physics-based Mode Switch Model (PMSM) of SI-HCCI mode switches has been developed, which combines a single zone physics-based SI model with a single zone detailed chemistry HCCI model. The PMSM predicts the shape of IMEP and CA50 SI-HCCI mode switch responses for a single cylinder natural gas engine.;Sensitivities of work output and combustion timing are calculated with respect to input variables and model parameters. A mode switch profile allowing SI-HCCI mode switches while holding engine torque constant is achieved using an optimization process that considers only conventional actuators of intake pressure and fuel injector pulse width. A similar optimization process is used to further improve mode switches using intake temperature adjustment.