Combustion-Timing Control of Low-Temperature Gasoline Combustion (LTGC) Engines by Using Double Direct-Injections to Control Kinetic Rates
Low-temperature gasoline combustion (LTGC) engines can provide high efficiencies and extremely low NOx and particulate emissions, but controlling the combustion timing remains a challenge. In this work we explore the potential of partial fuel stratification (PFS) to control the combustion timing by altering the kinetic rates of autoignition. The PFS was produced by a double direct injection (DDI) process using a GDI fuel injector, with 70 – 80% of the fuel being directly injected early in the intake stroke (start of injection = 60° aTDC intake) and the remainder being injected during the compression stroke (200 – 325° aTDC intake, 160 – 35° bTDC compression). The amount of mixture stratification was varied by changing the late-DI timing and/or late-DI fuel fraction.