Elastohydrodynamic Lubrication of Oil Film Seals Under High Speed Reciprocating Motion

1st Report, Theoretical Analysis of Elastohydrodynamic Lubrication for Oil Film Seals

Abstract

This study deals with oil film seals (floating bush seals) under high-speed reciprocating motion in hydraulic equipments. Two numerical methods of Elastohydrodynamic lubrication for seal performance are presented. One method is an approximate method on the assumption that profile of seal clearance is straight one. In another 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. Also, it is shown that rings with step on inner face are useful to hold clearance under high-speed condition.