喷油器柱塞副动态泄漏及特性

为了研究高压共轨喷油器柱塞副的动态泄漏特性，建立了柱塞副间隙燃油流动的数学模型，通过有限差分法对数学模型进行数值计算，研究了不同轨压下柱塞副燃油的平均动态泄漏率的变化趋势，与试验值进行对比，验证该数学模型的有效性，并分析了轨压、进口燃油温度、柱塞最大升程和喷射脉宽四种因素对柱塞副动态泄漏量的影响及在不同柱塞速度下，油膜压力、厚度和温度参数的变化趋势。结果表明，在一个喷油循环内，动态泄漏率的变化曲线与控制腔油压变化曲线相似，平均动态泄漏率随着喷油器的轨压、入口燃油温度和柱塞最大升程的增加而增加，但随着喷射脉宽的增加而减小；随着柱塞速度由正速度到负速度的过程，油膜的厚度逐渐变薄，油膜的温度整体上升，油膜的压力变小。

Study on Dynamic Leakage and Characteristics of Injector Plunger Pair

In order to study the dynamic leakage characteristics of the plunger pair of high pressure common rail injector, a mathematical model of the fuel flow in the gap between the plunger pair was established. The finite difference method was used for numerical calculation of the mathematical model, and the changing trend of the average dynamic leakage rate of the plunger pair fuel under different rail pressure was studied. The comparison with the test value was made to verify the validity of the mathematical model. The effects of rail pressure, inlet fuel temperature, plunger maximum lift and injection pulse width on the dynamic leakage of the plunger pair were analyzed, and the changing trend of oil film pressure, thickness and temperature parameters at different plunger speeds were also analyzed. The results show that the change curve of the dynamic leakage rate is similar to that of the control chamber oil pressure in a fuel injection cycle. The average dynamic leakage rate increases with the increase of the rail pressure of the injector, the inlet fuel temperature and the maximum lift of the plunger, but decreases with the increase of the injection pulse width. As the speed of the plunger changes from positive speed to negative speed, the thickness of the oil film becomes thinner, the temperature of the oil film rises as a whole, and the pressure of the oil film becomes smaller.