A Development of Gasoline Direct Injection Systems to Reduce PM and PN in Steady and Transient Operations

Abstract

Reduction of PM and PN are required for gasoline direct-injection engines in real driving conditions. Soot constitutes a major amount of PN, and it is caused by fuel wettings on each combustion chamber walls. Relationships between fuel wettings and PN in each injection conditions are clarified. An evaluation method for an injector aging was established to reduce tip-wetting and tip-soot in each operating condition. Effects of flow rate distributions of each injector nozzle on PN are also investigated. It shows that the biased flow rate distribution makes a robustness of PN characteristics in lower water temperatures worse.