Design of Self-restriction Hydrostatic Thrust Spherical Bearing (Fitted Type)

Ahmad Waguih Yacout Elescandarany

doi:10.11648/j.ijmea.20190704.14

Ahmad Waguih Yacout Elescandarany

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https://doi.org/10.11648/j.ijmea.20190704.14

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Abstract

This is the last part of the series studying the fitted hydrostatic thrust spherical bearing. It handles an unconventional design of this type of bearings. The conception of this design is to break the rules controlling the bearing restrictions, where it is believed that without restrictors no hydrostatic bearing could be got (axiom). The paper focused the effort to derive a general characteristic equation that can control the design in turn the bearing performance and behavior. This general characteristic equation, through its simple form, gives the designer the ability to get a comprehensive conception about his problem and widely opens the door in front of him to design a conventional or unconventional bearing whatever the bearing purpose. The effective parameters; needed to be known for designing the bearing; were concentrated into three items; the rotor speed, the seat dimensions and the lubricant properties. The characteristic equation shows that the seat radius and the inlet angle play the major role in determining the supply pressure, in turn the load carrying capacity. The inertia, the recess angle and the lubricant viscosity have the major effect on determining the bearing stiffness in case of the partial hemispherical seats while in case of the hemispherical seats the stiffness has slightly been affected. The design shows that the bearings with hemispherical seats have extremely low stiffness, practically zero stiffness and very high temperature rise, which make this bearing configuration invalid to be self restriction bearing; while the bearings with partial hemispherical seats have a very wide stiffness range allowing the designer to control and design the bearing with the stiffness needed for any purpose (from zero stiffness to extremely high stiffness). The lubricant temperature rises about three degrees centigrade which practically means that the bearing operates at constant temperature.

Highlights

The previous researches offered plenty of the traditional studies and designs of the hydrostatic thrust spherical bearing with restrictors or with self-compensation.Ahmad W
A bearing is designed as an example to test the ability of the new technique, through the general characteristic equation, to offer a self-restriction bearing i.e. restrictor-less bearing
The design technique is merely based on unifying the dominant bearing parameters, the supply pressure, the lubricant flow rate and seat inlet orifice diameter ( Ps .q, dio ) through the derived general characteristic equation to ease and simplify the bearing selection depending only on its configuration that succeeds to meet the required application demands

Summary

Introduction

The previous researches offered plenty of the traditional studies and designs of the hydrostatic thrust spherical bearing with restrictors or with self-compensation.Ahmad W. The previous researches offered plenty of the traditional studies and designs of the hydrostatic thrust spherical bearing with restrictors or with self-compensation. Yacout [1,2,3,4] studied the fitted type, with and without recess, of the hydrostatic thrust spherical bearing with capillaries and orifices restrictors finding the effects of the inertia, surface roughness and lubricant fluid viscosity on the beating performance and offering an optimal design of this bearing. R. et al [5] offered a design of a hydrostatic rotary bearing with angled surface self-compensation consisting of five precisely machined parts provided with a sealing system. It is concluded that the novel hydrostatic bearing is potentially useful for applications that require very high rotational precision and stiffness in a low profile package

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