Cold start control strategy of a two-stroke direct injection spark-ignited kerosene engine

The cold start control strategy was designed for a two-stroke spark-ignited kerosene engine with air-assisted direct injection. With the use of self-developed electronic control unit, bench tests were carried out to verify the accuracy of the control strategy under 4℃ ambient temperature, and the effects of the key control parameters on cold start performance were researched under about 14℃ ambient temperature. The experimental results showed that, the ignition advance angle had effects on late stage of starting process; after the successful starting, ignition advance angle with 40° before top dead center was most beneficial to accelerate the warm-up process. When applying the saturated ignition energy strategy, the cold start performance was the best, the average engine speed of warm-up process raised to the maximum level, and the related engine speed fluctuation reached to the minimum value. The fuel enrichment factor bigger than 2.5 improved the dynamic performance of starting process, whose speed raising rate was increased, but the variations of cold start process were almost consistent when continuing to increase the fuel enrichment factor from 2.5 to 4.5. The air injection timing angle from 40° to 60° before top dead center was helpful to successful cold start; moderately advancing air injection timing angle at warm-up condition can accelerate the warm-up process. The fuel to air injection delay had direct influence on the fuel air mixture process, which may affect the motor dragging and starting process, and rapidly realize the best successful cold start when the fuel to air injection delay was about 6ms.