Online Monitoring and Feedback Control of Ignition Timing Based on Ion Current Signal Phase in EGR Gasoline Engine

Abstract

Based on a 1.3L MPI turbocharged gasoline engine with high and low pressure EGR system, correlation between ion current signal phase and ignition timing under declared operating condition has been studied. The results show that higher EGR rate needs to cooperate more advanced ignition timing, which leads to advanced ion current signal phase. Both under high and low pressure EGR condition, correlation coefficient between ion current signal phase and ignition timing is over 0.7, including 75% experiment points is over 0.9, so ion current signal phase is able to estimate ignition timing. Base on this, an online monitoring and feedback control strategy of ignition timing is proposed, which is employed to record the times of actual ignition timing deviating from ideal ignition timing and adjust ignition timing. The average accuracy rate of online monitoring function is 97.2%. This strategy can help to judge whether the engine operates properly and avoid adverse consequences caused by inaccurate matching of ignition timing and EGR rate.