Analysis of EGR Cyclic Variations in a Direct Injection Gasoline Engine by Using Raman Scattering Method

The Raman scattering method has been developed for the simultaneous, cycle by cycle measurement of HC, O₂, H₂O, and N₂ in a direct injection gasoline engine with EGR. By using the Raman scattering method, the effect of EGR on stratified charge combustion can be investigated in a direct injection SI gasoline engine. The results show that (1) at the compression stroke homogeneous EGR gas exists, (2) variation of component mass fraction of EGR (qualitative fluctuation) introduced in the previous combustion cycle is the primary reason for EGR fluctuation, (3) under normal operating conditions, EGR fluctuation (component mass fraction and quantitative fluctuation) doesn't influence on the combustion fluctuation at the stratified charge operation.