Design model and analysis of a Hydrostatic Bearing for Hydraulic rotary actuators

Abstract

Hydraulic rotary actuators are actuators that enable the piston, which is moved linearly by hydraulic fluid, to rotate the shaft to which it is connected through an involute gear system inside and outside, between certain angles. In this study, hydrostatic bearing that use a fluid film for load support and movement precision in rotary actuators is implemented in place of standard bearing. These bearings work on the principle of hydrostatic lubrication, in which oil is pressurized and used to separate the surfaces from each other. In this way, it minimizes friction and wear, increases the efficiency and life time of the machine in which it is used. This article provides a brief overview of Hydrostatic bearing systems and hydrostatic bearing brake system and focuses on our work at HKTM on the application of these systems in rotary actuator.Mathematical modeling, flow analysis and structural design have been carried out in this study. By mathematical modelling, design parameters of the hydrostatic bearing under a determined load, such as film thickness, land length, orifice diameter of capillary restrictor, and operating parameters such as supply pressure, pad pressures, stiffness and flow rate have also been determined. Flow analyses have been performed to verify the fluid flow in the hydrostatic bearing and the required pressure within the bearing. This paper provides a detailed description of our research findings and conclusions.