Research on Influence of Valve Response on Transient Combustion and Emission Performance for Non-throttle Engine Fueled with E10

Non-throttle engine can greatly improve engine thermal efficiency and has considerable application prospect, but combustion and emission performance under transient conditions need to be clarified. This test studied the effects of valve lift response on non-throttle combustion and emissions performance under transient conditions by test and ANOVA. The results showed that for non-throttle engine, there shows a un-synchronization phenomenon between valve lift and in-cylinder combustion. When switching from high IMEP to low IMEP, faster valve control motor speed shortened excess air coefficient and cylinder pressure stability cycles. However, when switching from low IMEP to high IMEP, faster valve control motor speed caused cylinder pressure and IMEP deteriorated and misfire trend seriously. Especially, when excess air coefficient fluctuated higher than 1, NOx emissions deterioration occurred. The fluctuation of intake and exhaust valve lift under transient conditions led to fluctuation of excessive air coefficient, i-EGR rate, and other boundary conditions. Excess air coefficient dominated cylinder pressure and IMEP under light load, but the proportion of i-EGR rate and initial reaction temperature increased to 50% gradually with load increasing. I-EGR rate and excess air coefficient were important boundaries for NOx emission, but influence of i-EGR rate on HC and CO emission was limited.