A study on misfire control using crank angular velocity combustion feedback considering in-cylinder gas properties

Internal combustion engines have been strongly required to improve thermal efficiency and utilize a variety of fuels derived from renewable energy sources to achieve carbon neutrality. In terms of engine development, the stable control of ignition and combustion is the primary challenge in adapting to diverse fuels for the recently emphasized premixed compression ignition combustion and super lean burn. In this study, a misfire index was used as a detector for a premixed type of diesel combustion engine. Combustion feedback control was performed to control the target value of EGR based on the difference between the misfire index and its target value. To apply crank angle velocity to feedback control, this study implemented corrections and limitations to the misfire index based on in-cylinder gas properties. This was made possible because, during misfire events, the in-cylinder pressure at top dead center (TDC) is not influenced by combustion pressure. Additionally, this research enabled model validation of the phenomena for the first time. A novel structure was also established to learn the EGR correction amount from the deviation of the misfire index, marking the first empirical demonstration of its effectiveness. This research not only presents control examples for misfire countermeasures, which are crucial for the development of engines capable of utilizing diverse fuels but also contributed to mass production and practical application.