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To extend the operating range of a gasoline HCCI engine, the blowdown supercharging (BDSC) system and the EGR guide were developed and experimentally examined. The concepts of these techniques are to obtain a large amount of dilution gas and to generate a strong in-cylinder thermal stratification without an external supercharger for extending the upper load limit of HCCI operation whilst keeping dP/dθmax and NOx emissions low. Also, to attain stable HCCI operation using the BDSC system with wide operating conditions, the valve actuation strategy in which the amount of dilution gas is smaller at lower load and larger at higher load was proposed. Additionally to achieve multi-cylinder HCCI operation with wide operating range, the secondary air injection system was developed to reduce cylinder-to-cylinder variation in ignition timing. As a result, the acceptable HCCI operation could be achieved with wide operating range, from IMEP of 135 kPa to 580 kPa.

Schemes to extend the operational region of gasoline compression ignition were explored using single (optial) and 4-cylinder 4-stroke engines equipped with an electromagnetic valve train. This report focuses mainly on the use of direct fuel injection devices (multi-hole and pintle types),exhaust gas recirculation (EGR) through valve timing, and their effects on the compression ignition operating ranges, and emissions. Also considered is charge boost HCCI using a mechanical supercharger. The results indicated that use of either direct fuel injection or charge boost increased (relative to homogeneous charge operation using port injection) the upper load range from an IMEP peak of about 400 kPa to 650 kPa, but the use of direct fuel injection deteriorated both the co-variation in IMEP (up to about 6%) and the NOX emission levels (up to about 8 g/kWh). In contrast, charge boost retained the very low NOx emission levels of port injection HCCI.