An Improved Elastic and Non-Contact Smart Sealing Concept for Digital Micro Hydraulic Valves

Abstract

A non-contacting sealing concept is presented which employs an elasto-hydrodynamic principle to reduce an initially large gap between seal and counter-surface to a small value for tolerable leakage. The seal is a circular ring, made of polymeric material to enable the intended radial deformation. It has basically rectangular cross section but two slightly conical surfaces: The outer girthed area in order to get a hydrostatic feedback from the pressure field in the sealing gap; and the lower pressure sided front face to limit the radial ring deflection. An analytical model based on a perfect geometry assumption demonstrates the function principle and analysis the role of main design parameters. An FEM model which can take complex ring deformation and partial contact of seal with its counter-surface into account shows a deeper insight to effects not covered by the analytical model and shows a reasonable agreement with experimental investigations made with a prototype.

Theoretical and Experimental Analysis of a Non Contacting Elastohydrodynamic Sealing

“…The fluid film is modelled using what is known as the Reynold's user element, which results in a much faster operation than the built-in procedure for solving the Navier Stokes equations [20]. This user element, programmed in FORTRAN, allows the finite element discretization of the Reynold's equation [7,13] which is extended to cover sealing problems [21]. The Reynold's equation is an approximation of the Navier Stokes equation.…”