Simulation Analysis And Experimental Research On Wear Resistance Of Aluminum Alloy Spool Valve Under Polluted Conditions

The integral structure can reduce the volume and weight of the electro-hydraulic module of the automatic transmission while saving cost.However,because the material of the valve body and the valve core are respectively aluminum alloy and alloy steel,under the condition of oil pollution,the wall surface is prone to severe wear,which may lead to the decline of control quality and even affect reliability.In this paper,the shifting slide valve in the integral electrohydraulic module is taken as the research object,and the wear prediction model of wall surface is established to predict its wear under the pollution condition.And the influence of different pollution condition parameters on the wall wear is verified,and the wear law of the wall surface is obtained.The results of the study are expected to predict the wear state of the electrohydraulic module,providing effective information for its maintenance;at the same time,it has certain significance for improving the design and the life prediction.The main research work is as follows:(1)Taking the aluminum alloy slide valve which plays the role of shifting as the research object,combined with the theory of liquid-solid two-phase flow and the theory of erosion wear,fully consider the influence of turbulence and wall boundary layer on the movement of oil and particles,as well as the particle size distribution and particles shape,based on(computational fluid dynamics)CFD,the wear prediction model of aluminum alloy sliding valve wall is established.Then,the calculation task of the wear prediction model is completed by CFD commercial software Fluent.The prediction results show that the flow field characteristics change most at the valve port,and the oil flow near the wall will hinder the particles from hitting the wall surface;the trajectory of the particle is related to the position of the incoming slide valve;the more severely worn parts are farther away from the valve port as the valve opening is increased;the wear rate of the cylindrical wall of the valve core is gradually increasing in different circumferential directions,and the maximum wear rate is generated at the valve port end;the wear rate of the cylindrical wall surface of the valve sleeve fluctuates up and down in different circumferential directions,with large fluctuations in the first half and small fluctuations in the second half.(2)The three-dimensional calculation model of the internal flow field of the aluminum alloy spool valve is simplified.Then,the geometric model of the two-dimensional gap flow field is established,and the gap calculation grid is divided.The flow characteristics and particle motion trajectory in the gap were analyzed,and the wear of the surface of the fully matched area was predicted.Comparing the wear of the surface of the fully mated zone with the surface of the mating transition zone,it is found that the difference between the two is huge.The wear value of the fully mated zone surface is negligible and the wear zone is very small.Therefore,when the erosion wear analysis of the valve wall surface of the aluminum alloy slide valve is performed,the wear of the surface of the fully mated area can be ignored.(3)Based on the wear prediction model of the aluminum alloy slide valve wall surface,the influence of particle size,particle shape and pressure difference on the wall surface wear of aluminum alloy slide valve was obtained.The results show that the pollution condition parameters affect the size and distribution of the wall wear area and the distribution law and size of the wear rate in different circumferential directions.(4)On the test bench built,the aluminum alloy slide valve pollution wear test was carried out.the standard pollutant dust is added to the oil,and a test is carried out to simulate the wear of the aluminum alloy slide valve after the vehicle has traveled enough mileage.Finally,the valve hole diameter and roundness are detected.The test results are consistent with the prediction results of the aluminum alloy spool wall in different circumferential directions,which proved that the wear prediction method of the aluminum alloy slide valve wall surface is feasible and accurate.