Study On Temperature Rise Of Dry Dual Clutch During Starting And Shifting Process

The dry dual clutch transmission has been widely used in more and more cars because of their better power,comfort and lower manufacturing costs.As an important part of the transmission,the dual clutch plays the role of clutch separation and engagement when switching the odd and even gears.Due to the coordinated work of the two clutches,the power interruption during gear shifting is avoided.However,due to the structure and due to heat dissipation and other reasons,wear is serious.During frequent work,the temperature of the friction pair of the dual clutch will rise rapidly,which will affect the life of the clutch.Finally,this article focuses on the temperature rise of the clutch during starting and shifting,the following researches are done:(1)The vehicle dynamics model was established,and then the dual-clutch starting and shifting process was analyzed.The simulation model was established using Cruise software.The simulation obtained the parameters of clutch 1 and clutch 2 under normal starting conditions and frequent starting conditions.Including the rotation speed and the transmission torque,etc.,to calculate the heat flux.(2)The air velocity of the friction pair under 8 groups of angular velocity conditions was simulated using CFX,and the reasons for the difference in air flow velocity between the pressure plate and the friction plate were analyzed.This is used to calculate the convective heat transfer coefficient.(3)Based on Heat Transfer,calculate the heat flow distribution coefficient,heat flow flux and convective heat transfer coefficient,to get the temperature field of clutch under normal starting conditions and frequent starting conditions.The reasons for the temperature rise of clutch 1 and clutch 2 during starting and shifting in the two working conditions are analyzed in detail,the clutch bench is carried out to verify the accuracy of simulation.(4)In the perspective of the main factors that affect the temperature rise,several methods for optimizing the temperature rise are proposed for the temperature rise of clutch 1 and clutch 2 in two driving conditions.On the one hand,in response to the temperature rise of clutch 1 during gear shifting proposed in the dynamic analysis,the method of optimizing the shift strategy effectively reduces the temperature rise of clutch1;on the other hand,it is proposed that the temperature rise of clutch 2 is relatively high.A method to reduce the speed difference when the clutch 2 is shifted is proposed;finally,two methods to reduce the temperature rise are proposed for the phenomenon that the temperature of the clutch 1 rises rapidly during frequent starting.