Research On Finite Element Analysis Of Dry Double-Clutch Thermal Properties

As the increasing need of vehicle automatic operations, now the automotive automatic transmission technologies develop fast. The automotive automatic transmissions fall in such three categories as AT(Automatic Transmissions), CVT(Continue Variable Transmissions) and AMT(Automated Manual Transmissions). Especially the AMT, now many important automotive companies have paid much attentions to it for its high fuel efficiency, lower exhaust and keeping almost all the manual transmission industry invest.AMT is developed from the traditional parallel shaft manual transmission. The basic ideas of developing AMT is to make the manual transmission operated automatically with electronic control. In the course of development of the AMT, some defects of the ideas have emerged. According to the operation of the manual transmission , the shifting process includes disengaging clutch, setting the gear box to neutral position, selecting new gear position, shifting to the new gear position and engaging the clutch.During the process, when clutch is disengaged the power of the engine couldn't be transmitted to the drive wheels until the clutch is engaged again. The vehicle speed is decreased for the power interruption. This ruins the acceleration ability and the conformability of the vehicle.In the other hand, the AT is of the advantages of smooth start, speedy shifting and no bumping during the shifting. All of these come from its using of torque converter and power shifting, which means no power interruption during the shifting. The shifting of AT is carried out only through changing of states of two clutch in the transmission, which usually only takes 0.3s. These are the reason of its excellent performance.To take advantages of both AT and AMT and to avoid the shortcoming of AMT, a kind of double-clutch automatic transmission(DCT) has been developed.The clutch used in the DCT has two format-dry and wet clutch.This paper take the dry double-clutch as a model,according to the specialise analyse of the principle of structure about DCT, analysed the thermal field to the dry double-clutch.Primary including:the structural analysis of dry double-clutch; calculate the parameters of primary parts and analyse the theory of thermal field as also calculated the loading parameters;combine with the PRO/E to built the finite element model of dry double-clutch and select ansys as analytical software for thermal field;application ansys to calculate transient thermal field from the slide to totality incorporation;application ansys to calculate the thermal deformation as also heat stress about clutch plate, middle flywheel as well as friction disc,and analysis the results.There are five parts in the dissertation.First of all,introduced the structure,advantage,history,actuality and the future of double-clutch automatic transmission,analysed the meaning of study and the problem of the double-clutch automatic transmission,in this foundation rase up the primary research content of this textual.And then,made a comparison about the advantage and disadvantage between the dry and wet clutch, and chosen the dry double-clutch as subject investigated,also we have confirmated the structural shape of the double-clutch transmission, calculated the concretion parameters about the friction disc as well as the diaphragm spring. In addition,wo also introduced the correlation theory about frictional heating, defined the three kinds of boundary conditions as well as the initial conditions for the analyse, in the end calculated heat flux density in the slide processing, as the thermal loading applied to the under thermal analysis.In the third chapter built the finite element model of the dry double-clutch,in this chapter, first of all we have abstracted the theory of finite element as well as the software of finite element analysis-ANSYS;and according to the demands of the analyzine, through the simplify of the model,define the stuff performance parameters of the dry double-clutch,chosen the method to built the solid model,meshing the solid model to built the finite element model of dry double-clutch.And then, determine the loading and the boundary condition in the thermal analysis about the dry double-clutch, including to through the heat flux density calculated in the second chapter to determine the load step, determine the coefficient of convective heat transfer about the thermal analysis, define the material parameters, among many oter things, emphases the stuff coefficient of heat conductivity which have the major affection to the thermal amalysis, moreover, explained several hypotheses in the analyse;finally through introduce the solve flow about the thermo analytical,calculated the thermal field distribution at the phasic of slide about the dry double-clutch. From the results we know that, thermal field distribution not at all totality submit linear growth with the slide time, at the end of the slide, friction temperature begin fell off.In the last, is the calculation of thermal-stress field about the dry double-clutch. First of all, introduced the theory of finite-element method to the thermal-stress field; and then, determined the parameters as well as boundary conditions of thermal-stress field to the dry double-clutch , among many oter things, use the thermal field caculated in the fourth chapter as the temperature loading,among the material parameters,emphases introduced the thermal coefficient of expansion which was the major affection to the thermal-stress field; in the end, calculated the thermal deformation and thermal-stress field distribution about the middle flywheel, clutch plate as also the friction disc about the dry double-clutch, From the calculated distribution we know that, thermal-stress distribution not only relate with the temperature distribution,but also with the structure.This paper through the researching of working process about the dry double-clutch,analysed the thermal field as also thermal-stress field distribution among the slide of the clutch,these job will supply significant valueable reference to the design and improved design to dry double-clutch.