Identification method for design parameters of single-action tapered spool restrictors

Abstract

The performances of a hydrostatic bearing using the tapered-spool restrictors with appropriate design parameters is superior to other types of pressure compensation, that is the largest stiffness obtained under the lowest power consumption of supplying lubricant. However, the determination of design parameters is difficult, moreover, the simplification of the calculation formula will cause errors. Therefore, this study presents a method for identifying actual design parameters of the single‐action tapered-spool restrictor for actant values. Also, the influences of design parameters on the relationships between flow rate and pressure drop of this type restrictors are studied by both theoretical and experimental analyses. There are three design parameters that affect the characteristics of the tapered-spool restrictor, namely restriction parameter, compliance parameter, and restriction length ratio. Since both compliance parameter and restriction length ratio are functions of supply pressure, design parameters of a restrictor are determined simultaneously by solving a set of identification equations individually for the nominal value of each supply pressure. These identification equations are obtained by minimizing the sum of squared errors between the actual flow rate measured from experimental data and the flow rate calculated from the identification equations. Additionally, the advantages of the tapered-spool restrictors compared with other pressure compensation methods as well as the difficulties and errors in calculating design parameters are further elaborated in this study. Therefore, in order to design the appropriate parameters to match the hydrostatic bearing, the design parameters need to be identified when designing and calibrating such restrictors.