Hybrid combustion mode including flame propagation induced by spark ignition (SI) and auto-ignition could be an effective method to improve fuel economy and suppress engine knock simultaneously. An experimental research on controlled spark-assisted stratified compression ignition (SSCI) for this purpose was conducted in a gasoline direct injection (GDI) engine with high compression ratio. At wide open throttle (WOT) and minimum spark advance for best torque (MBT) condition without turbocharging, direct injection was used to form desired stoichiometric stratified mixture while 20% cooled external exhaust gas recirculation (e-EGR) was sucked into the cylinder. The combustion characteristics of controlled SSCI show two-stage heat release, where the first stage is caused by SI and the second stage is due to moderate auto-ignition. Compared with engine knock, the second stage heat release of controlled SSCI shows smooth pressure curve without pressure oscillation. This is due to the low energy density mixture around the cylinder wall caused by cooled e-EGR. The stratified mixture could suppress knock. Fuel economy and combustion characteristics of the baseline and the controlled SSCI combustion were compared. The baseline GDI engine reaches a maximum of 8.9 bar brake mean effective pressure (BMEP) with brake specific fuel consumption (BSFC) of 291 g/(kWh), and the controlled SSCI combustion achieves a maximum of 8.3 bar BMEP with BSFC of 256 g/(kWh), improving the fuel economy over 12% while maintaining approximately the same power. The results show that controlled SSCI with two-stage heat releases is a potential combustion strategy to suppress engine knock while achieving high efficiency of the high compression ratio gasoline engine.


    Access

    Access via TIB

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    Controlled SSCI With Moderate End-Gas Auto-Ignition for Fuel Economy Improvement and Knock Suppression




    Publication date :

    2015




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English



    Classification :

    BKL:    52.52 Thermische Energieerzeugung, Wärmetechnik / 52.30 Strömungskraftmaschinen, Turbomaschinen / 52.52 / 52.30



    Understanding Knock Metric for Controlled Auto-Ignition Engines

    Maria, Amir / Kar, Kenneth / Cheng, Wai K. et al. | SAE Technical Papers | 2013


    Understanding Knock Metric for Controlled Auto-Ignition Engines

    Maria, A. / Cheng, W.K. / Kar, K. et al. | British Library Conference Proceedings | 2013


    Fuel economy improvement using combined Controlled Auto Ignition (CAI) and Cylinder Deactivation (CDA) - an initial study

    Douglas,K.J. / Milovanovic,N. / Turner,J.W. et al. | Automotive engineering | 2005


    Modeling Investigation of Auto-ignition and Engine Knock by HO2

    Rutland, Christopher / Shao, Jiankun | SAE Technical Papers | 2014


    Knock improvement and performance in spark ignition engines with LPG-DME mixture fuel

    Raihan,K. / Omote,H. / Nakazono,T. et al. | Automotive engineering | 2008