高压共轨柱塞泵柱塞副摩擦学研究

Tribology Study on Plunger Pair of High Pressure Common Rail Pump

柱塞偶件作为高压共轨柱塞泵的重要精密偶件之一,柱塞与柱塞套之间的油膜特性直接影响泵的寿命。柱塞受到的径向力对油膜的厚度产生影响,可能产生润滑不良、加剧磨损。对柱塞油膜厚度的研究有助于解释其磨损失效原因。通过进行柱塞受力分析、油膜压力分析得出油膜厚度的变化情况。通过仿真计算不同柱塞位置的油膜厚度分布,得出柱塞副易受磨损的部位,并研究不同工作压力对油膜厚度的影响。对磨损后的柱塞偶件进行电镜扫描,分析其磨损机制。结果表明:当凸轮转过180°时,柱塞上端油膜最薄,此处最易磨损;当凸轮处于0°时,柱塞套下端油膜最薄;工作压力增大,油膜厚度减小。由电镜扫描结果可知,其主要磨损方式是黏着磨损和硬质颗粒的犁沟效应。

The plunger is one of the most important precision coupling in the high pressure common rail pump, oil film characteristics between the plunger and the plunger sleeve directly affects the service life of the pump. The radial force on the plunger can make a bad influence on the thickness of the oil film which may cause bad lubrication and wear. The study on the thickness of the oil film is helpful to explain the cause of wear failure. Through the stress analysis of the plunger and the analysis of the oil film pressure, the change of the oil film thickness was obtained. The oil film thickness distribution in different plunger positions was calculated by simulation, and the parts which were easy to be worn were obtained, and the influence of different operating pressure on the oil film thickness was studied. The worn piston pairs were scanned by electron microscope, and their wear mechanism was analyzed. The results show that when the cam is turned 180°, the upper part of the plunger is thinner, where it is most easily worn; when the cam is at 0°, the oil film at the lower end of the plunger sleeve is thinnest; with the increase of working pressure, the film thickness decreases. Scanning electron microscopy shows that the main wear mechanism is adhesive wear and ploughing effect of hard particle.