3 Key technologies for DCT automatic control

The idea of ​​DCT was born as early as 1933. Although it has outstanding performance, the complicated shifting process is an important factor that restricts its practical application. When driving a manual transmission car, the skillful cooperation required to control the clutch and the throttle has already put a higher demand on the driver, so that the difficulty of the driver controlling the throttle and the two clutches at the same time can be imagined. In recent years, the gradual maturity of electronic technology has prompted the development of DCT to enter a stage of rapid development.

3.1 Start control

When the vehicle starts, in order to make the two clutches have similar service life and ensure the quick and smooth start, the two clutches can enter the sliding state at the same time, and the starting torque is transmitted together to realize the vehicle starting. Because the uncertainty of the starting condition and the driver's operation intention change randomly, the control algorithm of the starting clutch should be able to accurately adapt to these changes. The fuzzy control algorithm with strong robustness can meet the needs of practical applications.

3.2 shifting rules

The main goal of studying the shifting rules is to make the car have the characteristics of flexible operation, safety, reliability, power and economy. The current advanced comprehensive intelligent shifting rule is based on the traditional shifting rules, with reference to the excellent driver's shifting maneuvering experience, taking into account the driver type, driver's intention, driving environment and driving state of the car, using fuzzy control and Intelligent control technology, such as neural network technology, generates a shifting law that optimizes power, fuel economy, exhaust emissions, and other performance to meet the driver's wishes.

3.3 shift quality

The clutch transmits torque by the friction generated by the friction element. In addition to the structural parameters, the friction torque is mainly determined by the friction coefficient and the compression oil pressure of the clutch cylinder. These two factors are variable during the clutch assembly process. Reasonable control of the change law of oil pressure during shifting can effectively limit the torque disturbance on the auxiliary shaft of the gearbox, and obtain good shifting quality, so that the vehicle speed can smoothly transition. The oil pressure control methods in practical applications mainly include buffer valves and proportional relief valves. The pulse width modulation signal optimized by the fuzzy control algorithm controls the pipeline oil pressure of the automatic transmission by changing the current of the proportional relief valve, thereby Improve shift quality.

4 Conclusion

The DCT is based on the development of a parallel-shaft manual transmission that inherits the advantages of a manual transmission and achieves power shifting, which not only ensures the acceleration of the vehicle, but also greatly improves the comfort of the vehicle. The DSG with dry clutch has the advantages of high transmission efficiency, good economy and low cost. It overcomes the defects of thermal load performance and service life and will be widely used in cars. As a rising star in the transmission family, the DCT control method is still in the process of research and practice. Advanced control methods such as fuzzy control and intelligent control are expected to improve the performance of the DCT, which in turn will improve the driving performance of the vehicle.

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