Based On The Theory Of Fluid-solid Heat Coupling Thansfer Friction Plate Heat Dissipation Characteristics Of The Study

The splitter has an important role in the drive system of a four-wheel drive vehicle,and the multi-plate clutch is a key component of the multi-wheel clutch type splitter of the four-wheel drive vehicle.The friction plate(active film)in the multi-piece clutch,the dual steel plate(driven piece)in the relative friction process kinetic energy into heat to make the friction plate temperature,thus affecting the transmission torque transmission performance.It is very important to study the heat dissipation characteristics of the friction plate of the splitter,and it is very important to predict the performance of the splitter.In this paper,research on the BMW multi-chip clutch-type splitter.Firstly,introduced the theory of tribological heat transfer,the theory of flow field and the heat dissipation theory of flow field.Established the heat transfer equation and the heat transfer boundary model,and obtained the heat flux density expression.The heat flux density of the friction plate and the dual steel sheet is distributed according to the internal and external diameter of the friction pair.Based on the computational fluid dynamics theory,three-dimensional turbulence numerical simulation method and RNG k-? turbulence model are determined.By modifying the turbulent viscosity,the RNG k-? model considers the rotation and swirl flow in the average flow,and can better handle the high strain rate and flow line bending a greater degree of flow.The choice of the theoretical model of thermodynamics and hydrodynamics provides theoretical support for computer numerical simulation.Secondly,in the finite element analysis software of Abaqus,the friction coefficient of the friction clutch is simulated,taking a pair of friction pairs as an example,after the model simplification,material definition,interaction setting,grid cell division and so on,the temperature field of the friction plate under different friction coefficient,different friction plate pressure,different rotation speed and different friction plates are simulated respectively.The friction plate temperature is higher than that of the dual steel sheet.According to the fitting model,the friction coefficient is 0.25,the friction plate pressure is 1Mpa,the relative rotation speed is 450 r / min,the number of friction plates is the highest temperature of the friction plate under 8 pieces,and the friction coefficient is the maximum temperature of the friction pair under the four variables.and the relative error of the maximum temperature of the friction plate is 1.13%,4.05%,6.14% and 7.48% respectively.The relative error of the highest temperature of the dual steel sheet is 9.31%,and the relative error of the friction plate is 9.31% 1.06%,4.93%,6.28%.The heat dissipation characteristics of the frictional discs in the lubricating oil are then studied.Taking the complete 8-piece friction plate as an example,the static and rotating domain grids established by ICEM CFD were introduced into Fluent,the VOF two-phase flow model was established,the free liquid level was defined by UDF,the RNG turbulence model was selected,Average heat flux.(Actual oil immersion depth of 84mm),1/3(actual oil immersion depth of 61.7mm),1/2(actual oil immersion depth of 86mm)and pressure plate pressure at 0.2Mpa,0.4Mpa,0.6Mpa under the flow field temperature distribution simulation analysis.Reveal the temperature distribution of lubricating oil and the location of the highest temperature.Finally,a multi-disc clutch test stand was established,and a splitter case was fabricated using a transparent PC material to verify the movement state and temperature field distribution of the lubricating oil in the splitter.The greater the friction plate pressure,the higher the highest temperature,the highest point appears in the vicinity of the initial free surface.The high temperature distribution area gradually spreads to most areas where the oil flows steadily and sprays,and the overall temperature inside the stripper housing also increases.Compared with the maximum temperature,the relative error is 12.6%,8.4% and 9.9% respectively.The relative errors are 13.1%,8.4% and 6.9% respectively under different pressures.