Study On The Textured Seal Interface Of The Rotary Lip Seals

Rotary lip seals are widely applied in the rotary machines due to their advantages of its simple structure,easy installation and reliable sealing performance,to prevent the oil leakage and exclude contamination.With the expansion in the applications of lip seals,more strict requirements should be satisfied in the sealing performance,tribological properties and service life.To meet the above requirement,the theoretical and experimental investigations were conducted on the textured sealing interface of the rotary lip seal.The effect of surface roughness topography and elliptical dimples on the lubricating properties and sealing performance were analyzed.Firstly,a 2-D axial symmetry model of rotary oil seal based on the finite element method was presented including the effect of such factors as the interference fits,spring force and medium pressure.The contact zone width and contact pressure between the lip and the shaft were derived.A 3-D FEM model was developed to compute the influence coefficient matrices for radial and circumferential deformations.Taking into consideration the coupling relationship between the deformation of lip seal and the oil film thickness,a soft elasto-hydrodynamic model of rotary lip seal was established and the numerical solution of lubrication equation and deformation equation were obtained.Then,based on the soft elasto-hydrodynamic model,the effect of the surface roughness and elliptical textures on the lubrication characteristics and sealing performance was analyzed.Numerical results showed that the effect of surface roughness cannot be ignored for both the untextured and textured shaft surface.The lubrication and sealing properties of oil seal can be improved obviously by the micro textures,especially under the condition of the high pressure and speed.Finally,a test rig about oil seal was designed to compared the effect of the surface roughness and the elliptic micro textures on the sealing performance of the lip seals.Results showed that the friction torque increases with the increasing roughness values for the untextured shaft surfaces.The textured shaft with inclined elliptic dimples greatly improve the reverse pumping capability and reduce the friction torque.To improve the sealing performance of oil seal,the geometric parameters of the micro textures were optimized and the values were consistent with the numerical simulation results.The study in the present paper proposed a suitable measurement for improving the sealing performance of rotary lip seals,which is validated numerically and experimentally.The research results are helpful for the surface texture design of the rotary lip seals.