增压汽油机早燃在线检测与诊断

Board Boosted Gasoline Engine Preignition Diagnostic

摘要:

基于缸内离子电流检测技术，在一台增压进气道多点喷射汽油机上研究了进气温度、负荷、点火提前角、空燃比对于早燃发生频率的影响.试验结果表明，在一定范围内提升进气温度并不会增加早燃发生频率，增大负荷及增大点火提前角将会增加早燃发生频率，缸内混合气加浓将有效抑制早燃发生频率但是会增加油耗.采用的离子电流检测技术，可以实时快速检测早燃循环.并与缸压阈值法相比，离子电流信号判断早燃更准确，能够识别全部早燃循环，包括燃烧压力较小的早燃循环，同时离子电流检测法能够在上止点前25°CA检测到早燃发生的特征信号，这为发动机采取早燃消除方法提供了技术可能.

Abstract:

The experiment was conducted on a MPI boosted gasoline engine to analyze the influence of intake temperature, engine load, ignition timing and lambda on preignition frequency on the basis of the incylinder ioncurrent detection. The results show that small variation of intake pressure will not increase preignition events significantly. Higher engine load and advancing ignition timing will lead to higher preignition frequency. Incylinder enrichment will decrease its frequency but a higher fuel consumption instead. At the start of preignition event, obvious ion current signal can be detected. Compared with the cylinder pressure threshold method, ion current detection can find out all the preignition events, including the cycles with lower combustion pressure. Especially, the characteristic ion current signal of preignition can be detected 25°CA BTDC. This provides a potential control to suppress preignition events for modern engines.