增压汽油机早燃在线检测与诊断

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.

Board Boosted Gasoline Engine Pre ignition Diagnostic

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.