Optimum design of bearing and seal parts for hydraulic equipment

Abstract

Reasonable design criteria for the optimum size of bearing and seal parts of hydraulic equipment are presented. The minimum power loss, minimum size (or maximum load-carrying capacity) and maximum moment stiffness, as well as maximum stiffness, are adopted as the optimum conditions. In this study, we treat circular hydrostatic thrust bearings as the bearing and seal parts. The basic equations considering the effects of cyclic changes in supply pressure and eccentric loads, and elastic deformation of the parts are derived. The design parameters are contracted to three direct parameters, i.e. the radius of the bearing and seal parts, the ratio of a pocket radius, and the aspect ratio of a restrictor. We derive analytically the optimum criteria of hydrostatic thrust bearings with a capillary restrictor under the condition of concentric loads in a steady state. Also we clarify the effects of unsteady state operating conditions, physical properties of fluids, elastic deformation and eccentric loads and evaluate the criteria by means of power losses, stiffness and size.