Gas Exchange Process of Four-Stroke Spark Ignition Engines Under the Condition of Partial Load, a Medium or Low Speed (3rd Report)

Abstract

Exhaust gas recirculation (EGR) is one of the most available reduction methods of NO concentration in the exhuast gas, and there are generally two ways in EGR: one is external EGR and the other is internal EGR that is mainly controled by the valve timing. In this paper, it is shown that the burned gas amount in the intake air charge, that is the amount internal EGR, depending upon the valve timing, throttle degree, mainfold volume, number of cylinder, and engine speed, can be predicted by the method of predicting the volumetric efficiency already written in the previous paper, 1st report. This method is examined to compare the predicted values with the experimental ones using CO₂ as the tracer gas and confirmed for good agreement of their tendencies. Moreover, the general effects of the valve timing on the internal EGR are shown by this prediction method.