Analysis And Optimization Of The Lubrication Characteristics Of A Multi-disc Clutch Limited-slip Differential Based On Fluid-solid-thermal Coupling

Electronic limited slip differential(ELSD)and multi plate clutch are important components in lateral power distribution of electric vehicles.Based on the research and analysis of the structural characteristics,fluid lubrication characteristics,convective heat transfer characteristics and torque engagement process of specific components,this paper puts forward a reasonable method of adding lubricating oil in the closed fluid domain,and analyzes the influence of structural factors on heat transfer Then,the torque engagement model of steady-state fluctuation stage of heat dissipation is built,and the influence of temperature on torque engagement is analyzed.The specific contents are as follows:Firstly,the physical model of the electronically controlled limited slip differential is simplified and the constitutive equation of fluid flow is introduced.After comparing the traditional CFD software with the meshless lattice Boltzmann technology,the computational fluid dynamics software XFlow is selected as the technical support of the simulation.The simplified heat transfer model was used to solve the problem of heat transfer enhancement.Secondly,in this paper,an optimization model of lubricating oil quantity considering the thermal effect of temperature is proposed based on the electronic controlled limited slip differential for electric vehicles.In this paper,based on the computational fluid dynamics(CFD)numerical simulation method,the simulation model of electronically controlled limited slip differential is constructed,and the monitoring points of oil velocity and temperature parameters are established;secondly,the influence of oil quantity on convective heat transfer performance in ELSD is determined by analyzing various working conditions such as different speed and different immersion depth;finally,the steady-state wave is achieved by temperature The optimization model is constructed with the post dynamic value and the time needed to reach the steady-state temperature fluctuation as the evaluation indexes.Taking the specific parameters as an example,based on the proposed optimization model,the quadratic response surface method is used to fit the equations of multiple groups of simulation results.It is concluded that the optimal lubricating oil volume is 37.21% of the total volume,which verifies the feasibility of the model.This method provides a new idea for determining the amount of lubricating oil in transmission parts.Then,the engagement characteristics of multi disc clutch during power transmission are analyzed.Through the mathematical model of the friction plate joint process,the Simulink model of the friction plate joint process is constructed,and through the simulation analysis of different structures and different environmental temperatures,the regularity of the oil film thickness,viscous torque and rough torque is explored.Taking the specific parameters as an example,when the temperature increases appropriately,the viscosity of the oil will decrease,the oil film thickness will quickly reach the equilibrium state,and the friction coefficient will increase The results show that the time in the engagement process of the friction plate and the dual steel plate will be reduced correspondingly,and the viscous torque transmission will be accelerated;the influence of temperature on the engagement characteristics of the multi plate clutch is mainly reflected in the speed of oil film change,torque change and torque change range;when the temperature is higher,the torque transmission is relatively faster,and the temperature rise has a greater impact on the viscous torque.The analysis process reveals the law of torque engagement in the steady-state fluctuation stage of heat dissipation after taking on the better amount of lubricating oil and the better shell size.Finally,a test-bed of forced convection heat transfer is designed and built,and the test verification is carried out based on the test-bed.During the test,the temperature rise of differential driven gear under two working conditions of 240 r / min and 300 r /min is measured,and then compared with the simulation test,the results verify the feasibility of the simulation test.