A Study of Gasoline-fuelled HCCI Engine Equipped with an Electromagnetic Valve Train

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 NO_X emission levels (up to about 8 g/kWh). In contrast, charge boost retained the very low NOx emission levels of port injection HCCI. At the lower load range, a small amount of fuel injection during negative valve overlap expanded the operational range at the lower load range. It is presumed that the EGR with negative valve overlap has a similar effect as injection during negative overlap namely the oxidation of residual unburned hydrocarbons from the prior cycle during this period. This facilitates compression ignition.