Analytical Wear Model of a Gerotor Pump without Hydrodynamic Effect

Abstract

The contact stress in a gerotor pump is addressed in this paper because the gerotor pump cannot be adjusted for wear. The first part of this paper presents a simple and exact rotor profile equations of the gerotor pump. In the second part of this paper, an explicit formula to avoid undercut in the inner-rotor of the gerotor pump is proposed by examining the minimum radius of curvature of the inner-rotor tooth profile on the convex section. It is found that undercut does not occur so long as the minimum value of the radius of curvature on the convex section is not less than zero. Next, the contact stresses without hydrodynamic effect between the inner and outer-rotors are evaluated through the calculation of the Hertzian contact stress in the rotor teeth. Based on the above results, we finally present the wear characteristics of pHVs factor, which is proportional to the wear rate, between the rotors of the gerotor pump under quasi-static and dry contact conditions.