喷油压力对柴油机瞬变性能的影响研究

The study of injection pressure on the transient performance of diesel

针对增压柴油机瞬态工况过渡期间产生大量烟度的问题,以一台高压共轨柴油机为研究对象,研究了在恒转速下通过改变扭矩的瞬时变化负荷工况下,轨内油压对柴油机缸内燃烧质量及排放性能的影响。结果表明在相同的负荷加载率下,以35%负荷为改变喷油压力负荷,喷油压力在此负荷之前保持与原机相同,之后在原机的基础上有相应的增加。并且缸内压力峰值和压力变化速率峰值以及最高温度最大放热速率在轨内油压增大的同时均有增大,并且对应时刻相应提前。利用分段喷射技术在负荷小于35%时降低轨内油压10 MPa然后在大负荷后提高轨内油压10 MPa能够将瞬变过程的平均油耗降低3.25%,但NOx排放没改善;当轨内油压改变量由10 MPa改为5 MPa时烟度和油耗分别减少11.85%和1.55%,但NOx排放仍无改善。

In order to solve the problem of heavy smoke during the transient operation of a turbocharged diesel engine,a high pressure common rail diesel engine is studied under the transient operation condition of changing Torque at constant speed,influence of oil pressure in rail on combustion quality and emission performance of diesel engine.The results show that under the same loading rate,the injection pressure is changed by 35%load,and the injection pressure remains the same before the load,and then increases correspondingly on the basis of the original.The pressure peak value,the pressure change rate peak value and the highest temperature maximum heat release rate both increase with the increase of oil pressure in the rail,and the corresponding time is advanced accordingly.The average fuel consumption can be reduced by 3.25%when the load is less than 35%,but NO_x emission can not be improved when the oil pressure in the rail is reduced by 10 MPa and then increased by 10 MPa,the smoke and fuel consumption were reduced by 11.85%and 1.55%respectively when the change of oil pressure in rail was changed from 10 MPa to 5 MPa,but NO_x emission is not improved.