Lateral Force Acting on the Sliding Spool of Control Valve Due to Radial Flow Force and Static Pressure

Qianqian Lu,Yangfang Wu,Jonna Tiainen,Mehran Kiani-Oshtorjani

doi:10.1109/access.2021.3112188

Qianqian Lu, Yangfang Wu + Show 2 more

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https://doi.org/10.1109/access.2021.3112188

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Abstract

The hydraulic sliding-spool valve is a key component to control the flow rates and thus pressures in different hydraulic volumes. The lateral force on the spool is one of the important effects resulting from moving resistance. This paper presents research aimed at understanding the effects of radial flow force and static pressure upon the lateral force. The radial flow force is calculated from three types of control surfaces labelled with square land, 45° conical, and round curved surfaces, for discovering the effects of control profile, combined with inlet and outlet control conditions. The pressure difference effect is analyzed along with six cases under the same orifice opening, and the radial flow force is found to vary linearly with the pressure difference. The results also indicate that the radial force for the inlet control mode is less than that of the outlet control mode. The jet angle is discovered to not only be related to the annular orifice opening and gap clearance, but is also influenced by the flow direction and control surface profile. The static pressure is the predominant factor in the lateral force compared to the radial flow force. The results indicate that the static pressure variation on the surface of the cylindrical spool shoulder increased linearly with the inlet pressure; and two stagnation points can be observed in the case of the valve cavity with oil passages on the same section, and square land control edge profile. The lateral force on the spool increases with the pressure, and could reach to the maximum of 300 N, implying that this force should be taken into account in the selection of an actuator, especially in high pressure applications.

Highlights

F LOW force is often considered as one of the critical factors affecting the performance of a hydraulic control unit
3) the radial flow force on the spool under the inlet control mode was less than the value under outlet control, and the force difference between inlet and outlet control of conical profile was the least compared to the other two profiles
The results demonstrated that the lateral force on the spool is affected by radial flow force, and static pressure distribution on the cylindrical surface

Summary

Introduction

F LOW force is often considered as one of the critical factors affecting the performance of a hydraulic control unit. A hydraulic spool valve with a spool sliding along its axial, is used to control flow direction, or flux by manipulating spool position or displacement. The expressions of steady-state and transient flow forces can be used to obtain the equation of motion of the valve spool. This equation of motion has been used to calculate the axial flow forces acting on the spool of the directional control valves, and compensates for the flow forces [3]. The importance of reducing the flow forces has been illustrated [4] when the flow forces are acting on the valve piston of the hydraulic sliding-spool valve, under high flow rate and pressure conditions. The spool profile of a hydraulic directional valve for compensation was studied [5], and a corrected equation

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