| Dual Clutch Transmission (DCT) is with high transmission efficiency, smooth shift, compact structure, good inheritance for manual transmission, low manufacturing cost and so on, and has wide development prospects. In recent years, DCT has been a hot spot of research and product development of vehicle automatic transmission technology at home and abroad. Many domestic enterprises, universities and research institutions carry out a long-term research for the DCT automatic transmission products. However, due to the strict technical blockade of foreign countries, there are no achievements of substantial breakthrough. This thesis takes the new 8 speed DCT designed independently as the study object, and carry outs research of automatic transmission electronic control unit TCU, design and implementation of system prototype. Then, the hardware in the loop experiment is carried out to test the automatic transmission effective function of TCU system. The main work and achievements are listed below:1.Based on the analysis on working principle of the mechanical variable speed drive system and the operating principle of actuators corresponds to power transmission path under different gear situation in the new 8 speed DCT, The logical relation between the electro-hydraulic servo control elements of the electro-hydraulic servo control-execution system and actuators of different gears is established to design the automatic transmission control logic of TCU system.2.Considering shift response and shift quality as the control target, based on the study of operating principle of shift actuators and working principle of electro-hydraulic servo control-execution system, the structural and operating characteristics of electro-hydraulic servo control elements is analyzed to decide to choose high speed on-off solenoid valve as electro-hydraulic signal conversion element of automatic transmission control.3.Having in-depth study on control method of high speed on-off solenoid valve as electro-hydraulic signal conversion element:based on MATLAB/Simulink software, the simulation model is established to study the dynamic response characteristics of valve and the control method of switch function and proportion adjustment function. The simulation results show that compared with the traditional steady-voltage control mode, combining the high frequency holding-duty-ratio PWM control mode and the optimization of key parameters effectively improves the overall response speed of high speed on-off solenoid valve. Besides, the effects of key parameters on spool suspension displacement and effective duty ratio are obtained, and the control method that the scope of effective duty ratio is effectively broadened by optimizing the low level of PWM drive signal is proposed.4.The TCU system prototype is developed, including the system hardware circuit diagram design, the PCB board, the manufacture, debugging and performance test of the system prototype, the programing, debugging and function test of TCU automatic transmission control software.5.The design and construction of an automatic transmission hardware in the loop test platform is completed, which is used to simulate the driving state of the vehicle to obtain the driving state parameters. Based on the LabVIEW and DAQ acquisition equipments, the PC control software of the test platform and the test software of TCU system automatic transmission control hardware in the loop test are designed. Besides, the TCU system hardware in the loop test scheme based on the test platform is designed to test the function of TCU system automatic transmission control. The test results show that the control performance of the TCU system meets the design requirements, and achieve the goals of R&D design. |
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