Study On Different Thermal Characteristics Of Double Clutches In Automobile

The dry double clutch is the most important component in a dry DCT(Double Clutch Transmission), which composed of an odd and an even clutch. The odd clutch is used to control the shift of the odd gear and the even one is used to control the shift of the even gear. With the dry double clutch, not only the non cutting power shift and non shock shift can be realized, but also the high efficiency and compact structure can be achieved, which is conducive to be the most promising transmission in the future. But the overheating and excessive wear are easily produced under the compact working condition and bad heat dissipation.Besides that,the whole assembly need to be replaced together once any part of the plate and lining was broken due to the attachment of the rivet,which will cause the high cost of the maintenance and repair. Therefore,the focus of the thesis,by contrasting and analyzing the start procession and the shifting procession from first gear to second gear,the most dangerous condition can be found.After that,the analysis of the dangerous condition and solution is vital and essential to prolong the use of DCT.In this thesis, firstly, the dynamics modle of the vehicle was built in AVL-Cruise and simulation has been done in three different working load during the start procession(start slow, start normal and start fast).The friction work and power of clutch odd and even can be calculated after the simulation, which contributes to one of the boundary condition of the thermal analysis.Secondly, the 3D models of the plate and lining were built and CFD was used to analyze the flowing condition on surfaces of the 3D models. The flowing condition in eight different speed were calculated, which conduces to the other boundary condition of the thermal analysis by the empirical formula and interpolation.The thermal analysis was obtained by the calculation of the boundary conditions.On the whole, the temperature of each clutch was increased along with the growing load by extracting and analyzing the different locations of the surface on the clutch and the increase of even clutch is much more than the odd one.The rapidly increase of even clutch was achieved under the high load.At last,the reason for the high increase on even clutch was explained in the aspect of the speed difference between engine and clutch,the control strategy to reduce the friction work was proposed under the guarantee of the necessary driving torque.