Abstract:

Based on a naturally aspirated in?cylinder direct?injection gasoline engine， the influence of high energy ignition， passive pre?chamber， and the combination of the two on the engine's combustion and emission characteristics under stoichiometric and lean burn conditions is studied. The results show that high energy ignition combined with passive pre?chamber can significantly reduce cyclic variation， shorten ignition delay and combustion duration， and improve thermal efficiency under low load conditions. The passive pre?chamber with high?energy ignition can slightly expand the lean burn limit from 1.4 to between 1.5 and 1.6； under stoichiometric conditions， the relative increase of thermal efficiency can reach up to 17.9%. Under heavy load conditions， high?energy ignition combined with ordinary spark plugs or passive pre?combustion chambers will not significantly improve the combustion performance. In terms of emission， high?energy ignition has less impact on emission performance， while passive pre?chamber has a more significant impact on emission. Under low load conditions， passive pre?chamber tends to reduce NO_x emission； under medium and heavy load conditions， passive pre?combustion chamber tends to increase NO_x emission. Under various loads， the HC emission of the passive pre?combustion chamber is slightly higher than that of ordinary spark plugs due to flame quenching and fuel hitting the pre?chamber wall.

Key words: high energy ignition, passive pre?chamber, combustion, emissions