Experimental Study On Contamination Stagnation Force Of Hydraulic Slide Valve Model

Hydraulic slide valve is one of the basic structural forms of hydraulic control valve.There is an annular clearance of several microns to tens of microns between the spool and body of hydraulic slide valve,which plays the role of guiding and lubricating the movement of the spool.Solid particulate contaminations in the working medium of the hydraulic system,which are equivalent to the size of the clearance,will follow the working medium into the clearance,hinder the flexible movement of the slide valve spool,and cause the of the hydraulic slide valve,which seriously threatens the stability,reliability and safety of the hydraulic equipment.In this paper,taking the annular clearance of hydraulic slide valve as the specific research object,the real-time contamination stagnation force change of slide valve spool under the influence of such factors as the clearance morphology,the size of particles and the concentration of oil particles was investigated by means of experimental measurement.Several simplified contamination stagnation models of slide valve were established,and the distribution characteristics of particulate contaminations in the slide valve clearance flow field was simulation calculated by Euler-Euler multiphase flow model of Fluent simulation software.The experimental measurements and simulation results show that:(1)the contamination force of moving spool is pulsating;(2)the sensitive size of solid particles is 0.7-0.9 times of the clearance,and the critical concentration of solid particles is 4% of the clearance is 0.6 times.Within the sensitive size range of particles,the contamination stagnation force of spool is geometric multiple with the increase of particle size.(3)For the clearance with non-ideal shape,the stagnation force of hydraulic slide valve is greater than that of ideal shape within the range of particle sensitive size;(4)the pressure equalizing groove can effectively capture and store the solid particle contaminants that invade the clearance of hydraulic slide valve,thus reducing the particle content in the clearance,and opening moment compared with trapezoidal and triangular pressure equalizing groove structure.The spool of the slide valve with the shape equalizing groove has the most obvious anti-pollution effect.