| As a key component in the engine fuel supply system, oil pump affects the engineperformance directly. With the increasing demand for diesel engine economy, power andemission performance, electronic high pressure common rail technology is the futuredevelopment trend. However, due to the high cost and maintenance restrictions, dieselmechanical oil pump is still widely used in non-road motor machine (NRMM), therefore itis necessary to study it. Meanwhile when pump operating at high speed, cavitations will begenerated in nozzle hole, which will have a significant influence on fuel oil beam and fuelatomization.On the basis of analyzing matching diesel engine4D160, this paper aims directly atstudying BH4HP fuel pump, fuel injection pump assembly and the cavitation characteristicsin nozzle hole. Specific research works are as follows,（1）The different principle of fuel supply and injection between the top clearanceplunger and flat top plunger pump was analyzed. On the basis of one-dimensionalsimulation, top clearance pump injection advance features were analyzed. To find out theeffect to injection characteristics, the height and depth of U159H plunger and U169A topclearance plunger’s height, depth and inclination angle were simulated and the structure ofplunger was optimized. The injection speed characteristic curve of two kinds of pump wasanalyzed, and the performance of the two pumps before and after optimization wascompared.（2）By Comparing the increment of low speed fuel injection quantity between the topclearance plunger pump and flat top plunger pump, the reason for top clearance plungerhigh free accelerating smoke was explained. Top clearance plunger structure was optimizedto meet the requirements. Matched with engine differences in the economy and powerperformance were compared between the top clearance pump U167A and flat top plungerpump U159H and the performance before and after optimization was compared.Three-dimensional simulation method was used to match the injector rate with the enginecombustion chamber and the performance of combustion and emissions of two pumps inthe cylinder before and after optimization at1500r/min and2500r/min was analyzed by the data of temperature, fuel concentration, NO and Soot emissions in cylinder.（1）Three-dimensional simulation methods was used to analyze how the inlet pressureand backpressure affect the cavitations characteristics in the spray nozzle at maximum lift,and cavitations impact on fuel injection and fuel atomization is researched. Top clearancepump U167A nozzle moving grid computing model was established. According to theactual situation, cavitations characteristics at the1500r/min and2500r/min were studiedand cavitations influence on the fuel atomization was analyzed. Different types of diesel(-20#,-10#,0#,10#) cavitations characteristics on cold filter plugging point were studied,and differences of types diesel in the flow field、fuel atomization and fuel oil beam in sprayholes were compared. |
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