Experimental research of the gasoline engine operated in spark ignition and controlled auto-ignition combustion modes

The paper presents results of the preliminary research of the gasoline engine with capability of controlled auto-ignition (CAI) mode of combustion. The research was conducted on the single cylinder engine with fully variable valve train and direct fuel injection. In order to achieve temperature of the in-cylinder load which allows for gasoline auto ignition, exhaust gas trapping technique was applied. The research engine was run with negative valves overlap and valves lift reduced to less than 3 millimeters. In order to control start of ignition and heat release rate different valves timings were applied. Comparison of the spark ignition and controlled auto ignition operation modes was done with the use of in-cylinder pressure, net heat release and incylinder temperature values. Analysis of the measurement data shows substantial decrease of heat release duration and peak in-cylinder temperature in CAI operation mode.