微运动下高压油泵柱塞副瞬态泄漏研究

Study on Transient Leakage Characteristics of Piston Pairs in High-pressure Pump under Micro Motion

共轨高压油泵的泵油能力及容积效率受柱塞副燃油泄漏的制约,而柱塞的微运动特性对柱塞副的泄漏有着重要影响。基于结构动力学与流体动力润滑理论,建立柱塞副微运动过程的动力学模型,分析柱塞偏移、倾斜的微运动特性;综合考虑柱塞微运动、柱塞副的结构变形以及燃油物性变化的影响,建立升程段柱塞副燃油瞬态泄漏数学模型,获得了微运动下柱塞副工作过程的瞬态泄漏特性,并进行试验验证。计算结果表明:在柱塞升程段,柱塞的偏移量先增大后减小,柱塞倾斜角先减小后而增大;相比柱塞副实测的瞬态泄漏,考虑微运动下的瞬态泄漏平均误差为3%,而不考虑微运动的瞬态泄漏平均误差为20%,所以考虑微运动的瞬态泄漏模型更精确。

The injection pressure and volume efficiency of common rail high-pressure pump are limited by the piston pairs interface leakage,which is influenced by the micro motion characteristics of piston.Based on the structural dynamics and the hydrodynamic lubrication theory,the piston pairs’kinetic model was established,and the micro motion characteristics,such as the offset and the inclined angle of piston,were analyzed.By considering the effects of the piston micro motion,the elastic deformations of piston pairs and the change of the physical properties of fuel comprehensively,the piston pairs’transient leakage model in the ascending section was established by comprehensively considering the effect of the piston micro motion,the elastic deformations of piston pairs,and the fuel property changes,and the characteristics of the piston pairs interface transient leakage was studied.The calculated result was validated with the measurements.The calculation results indicate that in the ascending section,the offset of the piston is first increased and then decreased,the inclined angle is first decreased and then increased.Compared with the transient leakage measured,the average error of the leakage calculated based on the model considering the micro motion of piston is only 3%,however,the average error of the leakage calculated based on the model without considering the micro motion of piston is almost 20%.Therefore,the model considering the micro motion of piston is more precise.