Experimental Study of the Gasoline Engine Operated in Spark Ignition and Controlled Auto-Ignition Combustion Modes

The paper presents results of research of a gasoline engine capable of controlled auto-ignition (CAI) mode of combustion. The experiments were conducted on a single cylinder research engine equipped with direct fuel injection and a fully variable valvetrain. CAI operation was obtained with the use of the negative valve overlap (NVO) technique. The engine was operated at variable rotational speed and load. Comparative analysis of performance, fuel consumption and exhaust emissions was made for both SI and CAI combustion modes.

Combination of variable valvetrain settings and variable excess air ratio allowed loads between 0.2 and 0.42 MPa IMEP in CAI combustion mode. Direct fuel injection provided the possibility to control the heat release rate via injection angle.