预喷射对高压共轨柴油机起动特性的影响

Effects of Pilot Injection on Start Characteristics of a Common-Rail Diesel Engine

为研究预喷射对高压共轨柴油机起动特性的影响,针对某柴油机厂生产的4dc型高压共轨柴油机建立了试验测控系统,提出了起动特性评价指标,通过试验研究了有无预喷射、不同预喷油量和不同预喷时间对起动特性的影响规律。试验结果表明:预喷射对于高压共轨柴油机起动性能的影响是很大的,引入预喷射之后,起动时间和HC排放有了明显改善;工况一定时,存在一个最佳的预喷射量,过大或者过小都会使起动时间增大,HC排放增多;同时,存在一个最佳的预喷射时间,过大或者过小都会使起动时间增长,HC排放增大。

To study the influence of pilot injection on star characteristics of high pressure common rail diesel engine, the test and control systems were built for the 4dc diesel engine manufactured by a diesel engine company, and the evaluating standard of the star characteristics of high pressure common rail diesel engine is proposed. With experiments, the star performances under different conditions, which include： with or without pilot injection, different pilot injection quantity, and different pilot injection timing, are researched. The test results show that pilot injection influences the start performance greatly. With introducing the pilot injection, the start characteristics of engine, which indicated by start time and HC emission, can be effectively improved. For a certain operation condition, there is an optimum pilot injection quantity which minimizes the start time and HC emission. Similarly, optimum pilot injection timing is existing to shorten the start time and decrease the HC emission.