Research On Powertrain Control Technology Of Commercial Vehicle AMT Based On Wet Clutch

Since the latest electronic control AMT in the word was manufactured by Isuzu and Subaru in 1984, technologies of commercial vehicle Automated Mechanical Transmission, both domestic and international, have been developing continuously. Problems such as shifting schedule, clutch engagement control, shifting quality and shifting noise were always the most important techniques of AMT. Although, many aspects of research have been conducted in the closed loop control of shifting quality, fuzzy control of clutch engagement and application of shifting schedule, the main clutch between engine and AMT was dry clutch in the vehicle equipped AMT. The smoothness of control effects in dry clutch engaging progress was still not satisfactory, that influence the stability of vehicle starting and shifting process based on dry clutch AMT. All these issues restricted the further application and popularization of AMT in the commercial vehicle market. Compared with dry clutch, the probability of reliability, cooling performance and characteristics of engagement and release process of wet clutch were much better.Combined with school-enterprise cooperation projects and on the basis of analyzation to technology development status of both domestic and international commercial vehicles equipped with Automated Mechanical Transmission, replaced the dry clutch between engine and AMT in the traditional commercial vehicles with wet clutch as main clutch for AMT, this dissertation was conducted thorough investigation in the powertrain system integrated control technology of commercial vehicles AMT based on wet clutch. The major research contents as shown:(1) On the basis of investigation and research to technology development status of both domestic and international Automated Mechanical Transmission and wet clutch, according to the analyzation of wet clutch engagement process, the wet clutch torque-transfer characteristic modeling and simulation was accomplished respectively aimed at squeeze stage, compaction stage and asperity contact stage during the engagement process and drag torque during the release process. Based on the modeling and simulation, the bench test was carried out to verify the effectiveness of wet clutch simulation model.(2) According to the entire vehicle and powertrain parameters of commercial vehicle AMT based on wet clutch, the entire vehicle modeling and simulation was carried out for the powertrain system of commercial vehicle AMT based on wet clutch. After the comparison and analyzation between the test data and the simulation consequence, it was shown that the simulation consequence could represent real vehicle condition reliably, and the effectiveness of entire vehicle simulation model was verified.(3) On the basis of analyzation for the influence to clutch engagement normal pressing force caused by the rotation speed difference between clutch driving and driven plate and accelerator pedal position, as well as the parameter-self-adjustable PID control theory of wet clutch engagement pressure, the fuzzy logical strategy of wet clutch engagement pressure was investigated sufficiently due to wet clutch rotation speed difference and driver’s intention in starting process. Considering the characteristics of fuzzy logical, the ant colony algorithm was adopted to optimize the fuzzy membership function of wet clutch engagement pressure in starting process.(4) On the basis of dynamics analysis in the AMT shifting process and drag torque characteristic of wet clutch, the study on synchronic speed control strategy of AMT shifting process was achieved and the double factors shifting schedule was established. Research has shown that, even in the completely separate state, thin oil film between the friction discs and steel discs could transfer torque(i.e. drag torque) by the viscous shearing force of hydraulic transmission oil. The drag torque when clutch was separate could be used to synchronize transmission speed and satisfy the requirement of speed matching to target gear in shifting process.(5) According to the parameters of powertrain system and entire vehicle simulation model, the simulation and analyzation of wet clutch torque transfer characteristics impact starting and shifting process was achieved. The simulation analysis in starting process shown that it was result of mutual action between engine output torque and viscous and asperity torque in the wet clutch engagement process. The quantity of asperity torque and viscous torque in wet clutch squeeze stage and compaction stage was significant factors which influence starting smoothness. The simulation analysis in shifting process shown that the drag torque of wet clutch possessed function of speed synchronization.(6) On the basis of research on powertrain system integrated control strategy of commercial vehicle AMT based on wet clutch, the powertrain system integrated electronic control system software and hardware development was achieved based on wet clutch.(7) On the basis of shifting schedule of commercial vehicle AMT powertrain system integrated control strategy, applied the electronic control system, the starting and shifting experimentation was conducted based on wet clutch commercial vehicle AMT powertrain system integrated control, and the experimental result verified the effectiveness of commercial vehicle AMT powertrain system integrated control strategy based on wet clutch in starting and shifting process.The research on powertrain system integrated control technology of commercial vehicle AMT based on wet clutch in this dissertation was provided with important theoretical and practical significance for further promote commercial vehicle AMT technological development and application of wet clutch in commercial vehicle AMT powertrain system.