Cold start control strategy for a two-stroke spark ignition diesel-fuelled engine with air-assisted direct injection

The control strategies of cold start were investigated on a two-stroke spark ignition diesel-fuelled engine with air-assisted direct injection. The successful cold start of the engine at 5 °C ambient temperature verified the control strategy. Bench tests at ambient temperature (9 °C) were performed to study and quantify the control strategies according to the engine dynamic characteristics, including the engine speed, cylinder pressure and exhaust emission. The ignition timing, ignition energy, injection timing and amount of fuel injected were quantitatively analysed using the cold-start control strategy. An ignition timing of 30-40°CA bTDC is suggested to reduce the transition time from the cranking process to the start-up process. The saturated ignition energy favours the cold start performance with a moderate to low fluctuation of the engine speed from the start-up process to the warm-up process. A proper amount of fuel injection can improve the dynamic performance of the start-up and warm-up processes. A rapid cold start with short cranking was employed at an injection timing of approximately 50°CA bTDC, and moderately advancing the injection timing was found to accelerate the warm-up process.