CLOSED-LOOP CONTROL OF COMBUSTION PHASING IN AN HCCI ENGINE USING VVA AND VARIABLE EGR

A homogeneous charge compression ignition (HCCI) engine requires closed-loop control of combustion phasing for reliable operation. Variable valve actuation (VVA) has previously been shown to enable cycle-to-cycle, cylinder-individual control with high precision, but suffers from a narrow operating range. Adding variable exhaust gas recirculation (EGR) to the closed-loop control structure can extend the operating range. A mid-ranging control structure is presented here for combined VVA and EGR actuations in a multi-cylinder engine. The control structure is simple to implement and preserves the fast, cylinder-individual, and precise actuation of the VVA system while extending the operating range. Experimental results verify the performance of the control structure.