Thermal Elastic Analysis Of Wet Clutch

The research subject of the dissertation stems from some type high-power automatic transmission development, aiming at independently developing design of a high-power automatic transmission.The wet multi-disk clutch is an important part of automatic transmission, its quality and performance directly affect the lifespan of automatic transmission. Thermal failure of clutch often appears in working process, friction does work between contact surfaces of friction pair, and produces large amounts of heat energy, which is absorbed by two parts, temperature fields of friction disc and steel disc change by this process, and then stress fields are generated, both changing is the major factor of the thermal failure of the clutch. Therefore, thermal-elastic coupling analysis and optimization for friction pair of wet multi-disk clutch have great significance and practical value, to improve bearing capacity of wet multi-disk clutch.The main contents of this dissertation are shown as follows:(1) The development tendency and present situation of research on clutch at home and abroad are reviewed, the research focuses on working principle and engagement process of wet multi-disk clutch, groove shape characteristics and lubrication mechanism of friction pair; A 3D model studied in this paper is established.(2)The research deduces thermal differential equation and thermoelastic coupling theory of wet multi-disc clutch. A dynamic model for vehicle specific driving cycle is established, friction power and work when friction pair of clutch is in the vehicle starting are studied by the AMESim software.(3)The friction pair meshing model in condition of thermoelastic coupling is established by using the finite element method, then the thermoelastic coupling boundary conditions are defined: heat flux caused by friction work and convective heat transfer by lubricants, stress boundary conditions are imposed in the next step. Based on above accurate boundary conditions, the temperature fields and stress fields of friction disk and steel disk are obtained, each measuring point of both fields' tendency over time are comparatively analysised.(4)The friction work produced in the engagement process of wet clutch is optimized, better performance parameters of friction pair are getted, which can reduce the friction surface temperature and heat failure probability, at the same time, bearing capacity of wet clutch is improved. The temperature field of friction disc is simulated using optimized model, before and after optimization distribution rule of temperature field are compared, aiming at verifying the validity of optimization.