Elastohydrodynamic Lubrication of Oil Film seals under High Speed Reciprocating Motion

2006 Fiscal Year Final Research Report Summary

• Project/Area Number: 17560121
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Design engineering/Machine functional elements/Tribology
• Research Institution: KYUSHU UNIVERCITY
• Principal Investigator: SAKI Kunio Kyushu University, Faculty of Design, Professor, 大学院芸術工学研究院, 教授 (00299398)
• Project Period (FY): 2005 – 2006
• Keywords: Oil film seal / EHL / Floating bush seal / Hydraulic cylinder / Vibrator / FEM

Research Abstract

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.