Design Of Fitting Clearance And Research On Leakage Characteristics For Mult-way Valve Of Tractor

The hydraulic system is the driving unit of tractor,its main function is to transfer power for tractor.As the core control component of the tractor hydraulic system,the performance of the multi-way valve has an important impact on the overall performance of the tractor.Because the multi-way valve is affected by the pressure field and temperature field in the working process,the spool and the valve body are deformed to some extent.At present,the problems of clamping and excessive leakage caused by the deformation of spool and valve body have not been solved effectively,which seriously restricts the working reliability of tractors.Therefore,it is of great theoretical significance and engineering value to design reasonable initial clearance,select appropriate materials,and consider the influence of various factors on the leakage of multi-way valve comprehensively to determine the minimum leakage parameters for the design,production and use of multi-way valves.Aiming at the above problems,this paper takes the multi-way valve of a caterpillar tractor as the research object,combines the special working environment and complex internal structure of the multi-way valves,fully considers the coupling relationship among fluid field,temperature field and solid field,an analysis scheme based on ANSYS-Workbench platform for heat-fluid-solid coupling numerical simulation is proposed,the flow field,temperature field and solid field are coupled analyzed.The influence of different oil temperature changes on the deformation of spool and valve body under maximum pressure is analyzed,the variation rule of the valve body and spool fitting clearance with temperature is studied in detail,and the optimal initial clearance of different fitting scheme is optimized,then the strength check of the spool and valve body material has been completed.Finally,the optimal fitting clearance and the optimal fitting scheme are obtained.What's more,the effects of spool diameter,fitting clearance,working pressure,eccentricity,coverage and oil viscosity on the leakage characteristics of multi-way valves are analyzed through AMESim simulation model in this passage.Then,the influence degree of different factors on leakage of the multi-way valve is obtained through the orthogonal test and the minimum leakage parameter of the multi-way valve is determined.Through the industrial field test,the test results and simulation results are basically consistent,which verifies the correctness of the analysis results.The optimal fitting clearance,optimal fitting scheme and minimum leakage parameters designed in this paper,which can minimize the leakage without clamping and satisfying the strength requirements.It solves the contradiction between“clamping” and “leakage” of multi-way valve effectively,reduces the incidence of multi-way valve failures,and improves the service life of products,bringing certain economic benefits to enterprises and society.