UPSTREAM PUMPING OF RADIAL LIP SEALS BY TANGENTIALLY DEFORMING, ROUGHSEAL SURFACES

This paper aims at a theoretical explanation of the following two expe rimental observations of radial lip seals: fluid film formation and up stream pumping action. The origins of these observations are still poo rly understood, A hydrodynamic analysis is presented for the fully flo oded contact zone of a smooth shaft surface running against a rough se al surface. Four roughness structures are considered: one-dimensional sinusoidal and two-dimensional sinusoidal seal roughness structures bo th without and with a tangential seal surface displacement. The tangen tial seal surface displacement is chosen asymmetric with the axial pos ition in the contact, It follows that the tangential deformation of th e one- and two-dimensional seal roughness structures used in this pape r can explain the aforementioned experimental observations and simulat e the observed order of magnitude of load-carrying capacity pump rate, and friction torque found in the literature.