Early exhaust valve closing ( EVC ) timings result in high residual fractions in the cylinder, decreasing air mass in cylinder per cycle, increasing combustion duration, and decreasing IMEP while the pumping loss is decreased.

• 排气门关闭越早,缸内的残余废气量增加,每循环进气量减少,燃烧持续期变长,PIMEP减小,然而泵气损失减小;