Multi-objective Optimization And Control Of Pre-shift Process For Wet Dual Clutch Transmission

The transmission is the core component of the car,and its own and its matching with the engine have an important impact on the power,driving comfort and fuel economy of the vehicle.The dual clutch automatic transmission(DCT)has the advantages of high transmission efficiency,fast shift response,and good inheritance with manual transmission production.Since its listing in the world in 2002,its market share has developed rapidly.In terms of DCT pre-shift,DCT achieves power-free interruption shift through pre-shift and dual clutch switching,which is widely used in automobiles.The quality of the DCT shift process is closely related to the pre-shift process,but at present the dynamic characteristics of the pre-shift process are not deep enough.There are problems such as high impact,long time,and poor economy,which cannot meet the requirements of high-performance transmissions with high efficiency and energy saving.This article relies on the National Natural Science Foundation’s key project "DCT Intelligent Control and Evaluation Method Considering Dynamic Service Performance and Driving Behavior and Driving Environment",number U1764259,focusing on a wet double clutch automatic transmission as the research object,mainly conducting the following research:(1)First,the physical structure of the pre-shift system is analyzed to establish the transmission system model and the synchronizer model.Then theoretically analyze all engagements in the critical phase of the pre-shift process.The pre-shift process is divided into eight stages according to the position of the joint sleeve,and the mathematical model is discussed and discussed for each stage.Finally,the dynamic model of each stage is coupled to establish a pre-shift simulation model.(2)The influence of the structure parameters of the synchronizer and the control parameters of the pre-shift on the quality of the pre-shift is analyzed,and the characteristic influence law and sensitivity ranking are obtained.Establish the pre-shift energy loss model,analyze the influence characteristics of the control parameters on the pre-shift energy loss,and obtain the energy loss influence law.Finally,using genetic algorithms,multi-objective optimization can obtain structural parameters and control parameters that can meet different driving needs.(3)Simulation analysis of the characteristics of external excitation on the pre-shift process.Quantitative design of the pre-shift upshift and downshift laws,which can meet the demand while reducing the number of synchronizer engagements.Build a mathematical model of the pre-shift control system to obtain the numerical relationship between the control current and the displacement of the coupling sleeve.The sliding mode controller is designed based on the model to precisely control the position of the joint sleeve.The simulation results show that the ideal displacement curve of the joint sleeve displacement tracking is good and has anti-interference ability.(4)Build a dual-clutch automatic transmission bench,and design a bench test control and signal acquisition system based on d SPACE.Through the bench test,the correctness of the pre-shift model and the effectiveness of the multi-objective optimized control parameter results were verified.The test showed that the optimized control parameters greatly shortened the pre-shift time and reduced the degree of impact.