The effect of EGR and two-stage turbocharging on combustion ,emission and power performance was investigated on a electronic control high-pressure common rail heavy duty engine .The result shows that the CO ,HC and soot emissions of two-stage turbocharged diesel engine are lower than the original under the same EGR rate .With the increase of EGR rate ,the maximum in-cylinder pressure ,the peak heat release rate and the in-cylinder average combustion temperature decrease and the ignition delay period almost keeps unchanged .Compared with the original engine ,two-stage turbocharged engine can achieve the higher EGR rate and can keep good power and economy performance in a wider range of EGR rate .With the increase of EGR rate ,the inhibition NOx emissions become more obvious and the lower soot emissions can be maintained in a wide range of EGR rate .The compromise between NOx emission and fuel consumption rate as well as soot emission is also significantly better than the single-stage turbocharged engine .%针对某电控高压共轨重型柴油机，研究了二级增压及EGR系统对燃烧、排放及动力性能的影响规律。研究结果表明，相同EGR率下，二级增压柴油机CO ，HC和炭烟排放均低于单级增压，且随EGR率增大，缸内燃烧压力、放热率峰值及缸内平均温度均有所降低，滞燃期变化不大。相比单级增压，二级增压能够实现更大的 EGR率，在更宽的EGR率范围内保持发动机良好的动力性和经济性；随EGR率增大，EGR对二级增压柴油机NO x 排放的抑制效果更为明显，且能够在更宽的EGR率范围内维持较低的炭烟排放；NO x 与燃油消耗率和烟度的平衡关系也明显优于单级增压。
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