中文摘要：

本文中通过对奥迪EA888 2.0L TFSI直喷汽油机进行台架试验,对比研究了压缩比改变前后发动机的离子电流与燃烧特性。结果表明：提高压缩比可使燃烧相位和离子电流相位提前;离子电流起始相位Ion10和离子电流差分谷值相位dIonvalley在反映燃烧相位时具有一致性,始终滞后于燃烧始点CA10和燃烧中心CA50一定的曲轴转角,约10°CA;压缩比从9.6提高到11.5,IMEP可上升约0.02MPa,相应指示热效率提高2%-3%;离子电流积分值Ionint与IMEP有很强的相关性,能够准确反映IMEP的变动;高压缩比使发动机爆燃倾向加剧,而离子电流振荡幅值fIonm和差分峰值dIonpeak与爆燃强度有很强的正相关性。

英文摘要：

Based on a bench test on EA888 2.0L TFSI direct injection gasoline engine,its ion current and combustion characteristics before and after the change of compression ratio（ CR） are comparatively studied. The results show that increasing CR makes both combustion phase and ion current phase advance; the ion current initial phase Ion10 and the ion current difference valley dIonvalley have good consistency in reflecting combustion phase,and always lag around 10°CA behind compared with CA10 and CA50; The increase of CR from 9. 6 to 11. 5 brings about a 0. 02 MPa higher indicated mean effective pressure（ IMEP）,accordingly the indicated thermal efficiency increases by 2% - 3%; the ion current integral Ionint is strongly correlated to IMEP and can reflect the fluctuation of IMEP accurately; High CR exacerbate the tendency of engine knock and the ion current oscillation amplitude fIonm and the ion current difference peak dIonpeak have strong positive correlation with knock intensity.