Transmission System Matching Control And Thermal Analysis Of Wet Dual Clutch

Dual Clutch Transmission (DCT) is a new kind of automatic transmissions, intrinsically eliminating torque interrupts during gearshift through one clutch separated while another clutch engaged combined with the advantages of mechanical transmission (MT) and traditional hydraulically mechanical automatic transmission (AT). DCT not only have some advantages such as simple structure and high efficiency, but only have some drawback such as complex starting and shift control strategies and bad clutch radiation characteristic. In this paper, clutch control strategies research of wet DCT during starting and shifting process, and thermogenesis and radiation equilibrium and failure mechanism research are carried out relying on a project of National High-tech R&D Program (863 Program)"Development of High Performance Automatic Transmission for Economical Car".DCT clutch control research during starting and shifting process. Adopted with benchmark test method, DCT vehicle crawling, starting normally and shifting process are analyzed with benchmarking test. DCT vehicle dual clutches combination starting and upshift, downshift control strategies are formulated。Based on above offline simulation conclusions, the slip power created on the clutches during starting and shifting process is analyzed to supply heat source boundary condition for the clutch thermal analysis. And the DCT special clutch towing torque phenomenon is analyzed for formulating synchronizer control strategy to reducing towing torque.Thermal equilibrium analyzed during wet DCT vehicle starting and shifting process. Clutch pressure and driver and driven rotation speed during starting and shifting process are test and measured to solved slip power generated during actual vehicle starting and shifting process. Temperature variation condition during vehicle starting, shifting and normal riding is monitored and cooling oil temperature real-time variation status with slip power is concluded to supply verification for clutch thermogenesis and radiation process.Thermal equilibrium of wet clutches computed theoretically. Adopted with finite element theory, coolant oil flow field in clutch grooves is computed and analyzed. According to actual structure, the relation between supply and demand of DCT clutches coolant oil is optimized. Convection heat transfer coefficient during slipping and synchronizing stage of friction pairs is solved, and thermal equilibrium on the clutches during all sorts of stages is analyzed. Slip power evaluating indicators reflecting vehicle starting and shifting quality are optimized.The research for dual steel pan failure mechanism of wet clutches. Against the warping deformation and local high hot spots problem of wet clutches during slipping stage, thermal stress coupling of wet clutches friction pairs during slipping stage is analyzed with NSYS/LS-DYNA commercial software, warping formal of dual steel pan plate under different thickness and different ring surface width is compared, the influence factors of thermoelasticity instability for dual steel pan is analyzed, the design procedure and method of wet dual clutches are proposed, and then the structure is optimized.