Elastohydrodynamic Lubrication of Oil Film seals under High Speed Reciprocating Motion

针对液压设备中高速往复运动下的油膜密封（浮动衬套密封），提出了一种弹性流体动力润滑的数值计算方法。该方法采用浮环柔度矩阵和基于有限元法的水动力分析。分析了液压、密封环尺寸、密封环材料和初始间隙对密封性能（最小油膜厚度和漏油率）的影响。结果表明，在高液压下，由于密封环的收缩位移，使泄漏量减小。为了验证数值分析的有效性，对聚酰胺树脂密封环进行了试验研究，试验结果表明，考虑环的热膨胀和弹性位移时，泄漏率的测量值与理论值吻合较好。此外，它被证实，环与台阶的内表面是有用的，以保持在高速条件下的间隙。

This study deals with oil film seals (floating bush seals) under high-speed reciprocating motion in hydraulic equipments.A numerical method of Elastohydrodynamic lubrication for seal performance is presented. In this method, compliance matrix of floating ring and hydrodynamic analysis based on the finite element method are used. Effects of hydraulic pressure, size of ring, materials of ring and initial clearance on seal performance (minimum oil film thickness and oil leakage rate) are presented. It is shown that the oil leakage rate decrease under high hydraulic pressure owing to contractile displacement of ring. And it is found that seal gap become null in high-speed condition, caused by negative hydrodynamic pressure generated in seal clearance.In order to examine the validity of this numerical analysis, experimental tests have been performed, using seal rings made of polyamide resin.Measured results of oil leakage rate are confirmed to be in good agreement with predicted ones considering thermal expansion and elastic displacement of rings. Also, it is confirmed that rings with step on inner face are useful to hold clearance under high-speed condition.