| With the rapid development of vehicle transmission technology,the power density of wet clutch is increasing,the speed is increasing,and the working condition of friction pair is deteriorating.The early damage of wet clutch caused by friction and wear has become a bottleneck restricting the life of vehicle transmission device.Based on hydrodynamic lubrication theory,rough surface elastic contact theory and heat transfer theory,this paper studies the friction characteristics,thermal elastohydrodynamic coupling effect and oil passage structure optimization of friction pair in wet clutch engagement process.Based on the multi-body dynamics and Hertz contact theory,the dynamic analysis model of clutch is established and verified by means of finite element modeling and bench test.The effects of friction plate speed difference,oil film thickness,surface friction coefficient and control oil pressure curve on the speed response characteristics and sliding torque of friction plate are studied.The friction characteristics of wet clutch friction pair under thermal elastohydrodynamic coupling effect are studied.The distribution of temperature,pressure and strain on the surface of friction plate and lubricating oil film are obtained.The effects of thermal elastohydrodynamic coupling boundary conditions and structural parameters on the friction characteristics are analyzed.A three-dimensional integrated optimization design platform is established,which integrates the flow field parametric modeling,flow field numerical analysis,experimental design method,response surface method and optimization algorithm.The effects of oil groove depth,oil groove width and oil groove number on the temperature field of friction pair are analyzed,and the structural parameters of oil groove are optimized,which provides the basis for the finite element simulation of flow field of wet clutch and the optimization of friction pair It can be used as a reference for structural optimization.The main contents of this paper are as follows.1)Based on multi-body dynamics,the dynamic analysis model of wet clutch and the sliding friction characteristics of wet clutch under lubrication conditions and surface friction coefficient are established and verified in ADAMS.The effects of friction plate speed difference,oil film thickness,surface friction coefficient and control oil pressure curve on friction plate speed response characteristics and sliding torque are simulated and studied.2)In order to study the influence of friction pair parameters on Thermal Elastohydrodynamic coupling characteristics of wet clutch,considering the influence of temperature rise on oil parameters,combined with the heat exchange model of friction pair,the thermal elastohydrodynamic coupling characteristics of wet clutch were analyzed in ANSYS The thermal elastohydrodynamic coupling model of wet clutch was established in workbench,and the distribution characteristics of lubricating oil pressure field,temperature field,stress field and strain field of friction plate and dual steel plate were obtained.The influence of oil film thickness,driving end speed,engagement oil pressure and surface roughness on friction pair sliding friction characteristics was explored,which provided reference and basis for wet clutch optimization design.3)In order to effectively reduce the thermal stress of friction plate in the sliding process and improve the service life of friction plate,the mathematical model of lubricating oil channel parameter design optimization was established by comprehensive experimental design,response surface method and optimization algorithm,and the integrated optimization design platform of oil channel parameters of wet clutch friction pair was built.The sequential quadratic programming method was used to explore the optimal temperature rise of wet clutch friction pair The influence of groove depth,groove width and groove number on the temperature field of friction pair was studied.The optimal design of groove structure parameters was carried out with the maximum temperature of friction plate as the optimization objective.4)Based on the bench test platform of wet clutch,the temperature measurement test scheme of wet clutch friction plate is designed,9 groups of grooved friction plate test samples are processed,and the influence test of the relative speed,engagement pressure and lubrication state of the dual parts on the variation law of the temperature field of the friction pair is completed.The accuracy of the simulation method is verified by comparing and analyzing the test results with the calculation results of the finite element model. |
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