Study On Slipping Status Of Diaphragm Spring Clutch During DCT Shifting

The Dual Clutch Transmission (DCT) is a brand new kind of automatictransmission，The most important feature of this system is the use of input shaft with TheNested Structure and connect two sets of clutch system, during the shifting, one clutch wasalready working before another disengagement. So the whole shifting process can withoutpower interruption, which like AT can achieved, with broad application prospects andpractical significance.This thesis is funded by Chongqing Municipal Education Commission (ProjectNumber： KJ080619).Study with how clutch torque, degree of shock, sliding friction workchange with the influence of the slip velocity of clutch and the temperature change.Establish Simulation Models by Matlab/Simulink and analysis the shifting process. Themain research contents include：1、 Point out limitations of the existing mathematical model about DCT shifting.Making the friction coefficient which is very much effected constant or simple linearfunction when calculate the output torque.So the torque only related to clutch pressure,which is not coincidence the actual working conditions. Lots of researches andexperiments can prove that the changes of relative sliping velocity between the frictionsurface, displacement and temperature can course friction coefficient changes too,sometimes even60%. It is very clear that original method of calculation gives mistakesmore or less, and makes the analysis of clutch control theory meaningless. The main pointof this paper is make a extend of original models, see what happened about the outputtorque when friction coefficient and temperature changes.2、 Build the sliping speed model of torque based on the studies about friction modelby foreigners and dynamic model of DCT torque. Make the slipping speed to beconnection between torque and stages of shifting, Divided into two categories whenmodeling:frist,divide by different kind of friction model which selected, then compare thetorque which impact by friction model; Another, modeling by five phase stage whenshifting and compare with the frist method and find out how torque changes when slippingspeed and temperature different.3、 Temperature is a very important factor for the torque change during the shiftingprocess of DCT. Many experiments had confirmed that the shape of friction disk, friction coefficient, wear volume, the shape of pressure plate, the elastic coefficient of diaphragmspring are all affected by temperature. During working time, the temperature inside DCTwill change a lot, but now there is only a few research about that, this paper build atemperature model base on manual transmission with single clutch and control strategy ofDCT. Finally output the friction coefficient which is most effective of DCT shiftingprocess. Analysis how temperature affect the torque, friction work and the degree of shock.4、 Add temperature model and speed model to the vehicle model, which includeshifting, dual clutch, clutch control model.Finally get torques, friction work and impactsfrom the new vehicle model.5、 Compare and analysis the torque, friction work, impact which ouput by vehiclemodel.Paper use two method to do the research:1, Based on friction model, compareresults to find which friction model give the most impact during the whole shifting process;2,Based on different phase stage of shifting, find how friction model affect the outputs inevery stages and which factor give the most and longest impact. Finally, give a wholereport about what friction means to the whole DCT shifting process.