Research Of Strategy On Chery CVT07 Type Automobile Continuously Variable Transmission

CVT has long been an ideal automotive gear-box. By continuously variable transmission, the ratio of automotives can be adjusted continuously, which ensures that the engine works according to the optimum economy fuel-consumption line, and so the fuel economical efficiency has been increased, while nocuous gas' exhaust decreased. Meanwhile the efficiency of CVT is higher than that of AT, further more it makes vehicles shift more steadily, thus passengers will feel more comfortable.The mechanical structure and the principles of dry hybrid belt continuously variable transmission (A-CVT) are introduced in the discourse, the structure of the electromagnetic clutch and its merits as well. The torque of magnetic powder clutch is transmitted by electromagnet force, and there's a linear relation between its output torque and excitation current. Therefore as long as the excitation current is under control, the output torque is also mastered. The engaging process of the clutch is complicated when automotives start, and it is difficult to modulate precisely, so a fuzzy control strategy for clutch current is proposed, to wit the current of the electromagnetic clutch is decided by the throttle opening, variance ration of the throttle opening and the engine speed, according to drivers' experience. Based on the fuzzy control algorithm, the fuzzy control table for MCU is computed. And that the ratio of the gear-box is controlled by traditional PID controller, which is also designed. What's more, segmentation control is adopted, fit for different situations.The CVT controller designed in this discourse focuses on analyzing band wheel and belt, based on which contol module is established, as well as the control strategy for the timing motor.PIC18F6620 of Microchip is selected as MCU for TCU in this discourse. In addition the signal detecting and driving circuits are introduced briefly. The engaging control of electromagnetic clutch for automotive starting is implemented by fuzzy control altorithm. Self-adaptive PID control is applied to the adjust the ratio of A-CVT. Finally, the programmes that meet the control orders were written.The parameters are set up on the simulation test-table for the first time, TCU was used in the experimental car Matizâ…¡to match and demarcate the parameters, finally accomplished the experiment that the country stipulates. The function testing by the national automotive test centre shows that the controller has good control effect.