Design of Self-Compensating Hydrostatic Bearing For Actuators

Self-compensating hydrostatic bearings overcome disadvantages of other types of hydrostatic bearings like need to hand tune the restrictors, high sensitivity to manufacturing errors and also the problem of clogging. In addition they also retain all the benefits of hydrostatic bearings such as very high stiffness and straightness characteristics. With four pads and four integral annular orifices in the hydraulic actuator bearing uses variable orifices as a function of the radial eccentricity between the body and the shaft such that movement in any lateral direction can be reduced significantly (using self-compensation principle). In present paper, we analyze one such design for a hydrostatic bearing for actuators. The geometry of the pad and its effect on loading capacity has been analyzed using model of viscous flow through two parallel plates. We also propose two more approaches to mathematically model the system and optimize the geometry in order to achieve highest loading capacity, stiffness and straightening characteristics possible in the design. One of the other two approaches is writing down the Reynolds Equation for the pad geometry and solving the partial differential equation thus derived by numerical techniques. The second of other two approaches is to use CFD tool to simulate the flow in bearing and see its characteristics under different loading conditions and pad dimensions. We have proposed these methodologies and lay the future scope of this work to optimize the entire design.