Study On Torque Response And Reserve Coefficient Of Wet Clutches Under Braking Condition

The wet clutches are key components of the mechanical transmission system,which achieve good coordination of the heavy vehicle and the transmission device by effective control of the mating and disengaging of the friction pairs.The clutches generate a large amount of frictional heat under the motion of the active and passive ends.At the same time,the current development trend of mechanical transmission goes to miniaturization,lightweight,which makes the power density and transmission speed of vehicles improve continuously.It will cause friction ablation,deformation and severe wear phenomenon,and even sintering as a whole.In this paper,the frictional torque model of the friction pairs under the braking condition is established,and the influence of the working parameters and the material parameters on the friction torque is analyzed.Finally,the rationality of theoretical modeling is verified by experiments.This paper mainly completes the following work:First of all,according to the theory of tribology,the theory of hydrodynamic lubrication and the viscosity-temperature characteristic of oil under different pressures,the friction of single friction pair under local contact condition is established using non-uniform contact torque calculation model.The friction torque in the braking process is determined by the difference of the rotational speed of the main passive end,the control oil pressure and the working time and other physical changes in the law.Secondly,the behavior of friction pairs in the process of relative motion was analyzed,and the contact area and contact depth of friction pairs were analyzed.The change law of the contact area under different warping modes and the effect on the friction torque are analyzed by using the finite element software.Thirdly,the influence of contact pressure on the torque of the friction elements was analyzed.The viscosity of the oil was analyzed according to the contact pressure and temperature.Based on the assumption of contact area,the formula of friction torque of multi-plate clutch under braking condition is established and its influencing factors are analyzed.Finally,the method of testing the clutch torque is studied,the dynamic process of clutch speed,torque and braking torque are tested.At the same time,a model of multi-chip wet clutch reserve coefficient design is established,which provides an effective optimization basis for the lightweight design of the clutch.