A Study of Engine Out PM Emission Mechanism under Low Temperature Transient Condition and PN Reduction Technology for Direct Injection Gasoline Engines

Abstract

The mechanism about in-cylinder phenomena which is the main source of Particulate Matter (PM) emission under low temperature transient conditions before warm-up is analyzed in this study. As a result, a key parameter of the Particulate Number (PN) reduction under low temperature transient conditions is clarified. It can be stated that larger cycle to cycle carryover fuel film on the combustion chamber wall makes higher PN that is clarified in PN evaluation including transient condition. For PN reduction, cycle to cycle carryover fuel film should be considered. Therefore carryover fuel prediction tool has been constructed. And then, counter measures are found from those clarified phenomena.