Heat Load Research For Clutch Of DCT During Vehicle Starting

Dual-clutch Automatic Transmission (DCT) is a new automatic transmission developed on the basis of the electronically controlled Mechanical Automatic Transmission ( AMT) technology. DCT has simple, efficient transmission characteristics like Manual Transmission(MT) and can shift rapidly, which overcomes the AMT weakness of shifting power disrupts. DCT has become the new direction for the development of broad market prospects for a vehicle automatic transmission, because of the AMT advantages and the AT advantages of power shift, the good shift quality and dynamic and economic vehicle nature of the DCT.There are two kinds of clutches currently used in a DCT, wet and dry. Dry clutches have the advantages of simple structure, high transmission efficiency and low cost compared with wet clutches. But in order to avoid power interruption when dry clutch shift, the two clutchs switch unavoidably to produce the torque transmission overlap, then leading to a lot of sliding friction heat. The wear of the friction disk increases with the pressure-plate temperature-rise. When the work surface temperature of the pressure is over 180 ~ 200 ? C, friction-wears increases sharply. Temperature-rise depends on the heat capacity and heat dissipation capacity of dry clutch. So the heat dissipation is a key to DCT carrying capacity and working life.The paper studies the sliding friction process of clutch with temperature-rise issues, produced in dry dual clutch automatic transmission when vehicles start. The main contents are as followed:①Dry clutch friction materials, the type of friction and friction process were explained. Key performance parameters and the failure mode of dry clutch, evaluation parameters of heat load in the process of friction are calculated;②The start control strategy using two clutches is made. There is dynamic analysis for DCT transmission system. Mathematical models of the engine, double-clutch, and the slipping work are established. The car in different loads on ordinary road when doing climbing starting work is simulated under MATLAB / SIMULINK, then the slipping work curve produced under different work conditions;③Based on the heat transfer theory, boundary conditions for thermal analysis of clutch friction are acquired. The finite element models of clutch friction disk and the pressure plate are established. Temperature rising of them is acquired and their transient temperature field distribution is obtained using ANSYS software;④Through the front studies temperature rising of pairs, we determine the influence factors of temperature rise of clutch friction pairs. It is useful for reducing the temperature rising, carrying capacity and enhancing the service life of dry type structure of dual clutch design and cooling systems and equipment design;⑤Temperature-rise and wear testing system is studied.The dry clutch simulation test system is designed.The basic structure of test bench and the testing process are established.