为了提高柴油机低温起动速度和平稳性，在减小起动喷油量及增加起动阻力矩条件下，向柴油机进气道内预喷不同量的乙醚，研究乙醚助燃对柴油机起动循环数和燃烧排放特性的影响。结果表明：在标定油量下，进气道预喷少量助燃乙醚对起动循环数没有明显影响，但起动过程最高缸压及最大压力升高率显著增大；预喷助燃乙醚并减小起动喷油量能有效改善柴油机的起动粗暴性；减少起动喷油量并增加起动阻力矩时，在进气道预喷占起动初始循环油量热值20%的乙醚，能有效加快起动过程，将起动时间提前3～5个循环；进气道预喷乙醚后燃烧放热提前，放热率峰值减小，压力升高率降低，起动燃烧过程更加平稳，但会导致起动过程HC和CO排放增多。

In order to improve the low-temperature starting pace and stability of diesel engine, different amounts of ether were pre-injected into the intake port of diesel engine under the conditions of reducing the fuel amount of starting and increasing the starting resistance torque. The effects of ether promoting combustion on the number of starting cycles and the combustion and emission performance of diesel engines were studied. The results show that pre-injecting small amount of ether in the intake port has little effect on the number of starting cycles, but leads to the significant increase of maximum in-cylinder pressure and maximum pressure rise rate during the starting process after the fuel injection volume is calibrated. It is also found that preinjecting ether and reducing the fuel amount of starting can effectively improve the starting roughness of diesel engine. When reducing the fuel amount of starting and increasing the starting resistance torque simultaneously, the starting process accelerates with the advance of 3 to 5 cycles by pre-injecting ether in the inlet that accounts for 20% of the calorific value of the initial circulating fuel. The combustion process advances, the peak heat release rate and the pressure rise rate decrease, and the starting combustion process becomes more stable, but the HC and CO emissions of starting process increase after pre-injecting ether in the intake port.