Research On Shift Control Strategy Of 32-Speed Binary Logic Automatic Transmission For Vehicles

The Binary Logic Transmission（BLT）is an emerging automatic transmission at home and abroad.Because of its high transmission efficiency,high power density,strong load-bearing capacity and compact structure,it has been tried on foreign military vehicles and other special vehicles in recent years,and domestic trial research on the BLT has also begun.The 32-speed BLT has denser gears,it can achieve the function of“quasi” continuously variable speed.Compared with the continuously variable transmission,it has stronger load-bearing capacity and higher reliability by using the double internal planetary row.However,the working characteristic of super multiple gears is bound to cause frequent shift problem,and it also puts forward higher requirements for the working condition adaptability of the BLT.Therefore,the 32-speed BLT requires more complicated shift schedules.Simultaneously,the BLT achieves 32 speed ratios through five series double internal planetary rows operating together,and each planetary row is coupled with each other.Compared with the traditional hydraulic automatic transmission,the shift process control of the 32-speed BLT is more complex.Therefore,the thesis aims to design the shift schedule and solve the problem of shift process control of the 32-speed BLT.The main contents of this thesis include the following elements.Firstly,based on the MATLAB/Simulink software,the control-oriented 32-speed BLT model,electro-hydraulic control system model,engine model and vehicle dynamics model are built respectively.The 32-speed BLT model mainly includes the steady-state motion model of shift elements in each planetary row,the friction torque model of wet V-groove clutch,and the double internal planetary row model.The electro-hydraulic control system model mainly includes the proportional solenoid valve model,which is used to realize the conversion of electro-hydraulic signals.Based on the steady-state data of the engine,the engine model is built,and the longitudinal dynamics model is built for a traditional fuel vehicle.The above models are integrated to build a 32-speed BLT physical simulation model for the verification of the control strategies in this thesis.Secondly,aiming at the working characteristic of super multiple gears of the32-speed BLT,the shift schedules of power,economy and man-vehicle-road closed-loop system are designed respectively.The traditional shift schedules lead to the frequent shift and cumbersome solution of jumping points of the 32-speed BLT.With reference to the speed ratio adjustment strategy of the continuously variable transmission,the dynamic and economic speed ratio adjustment strategies suitable for the 32-speed BLT are proposed,which can ensure the power and economy of the vehicle while realizing reasonable jumping gears.Simultaneously,considering the impact of the dynamic characteristics of the engine and vehicle,and the different road conditions on the shift schedules,the above shift schedules are revised based on the vehicle acceleration and road gradient.The proposed control strategies are simulated and verified based on the32-speed BLT physical simulation model.The results show that the above shift schedules can meet the shift requirements of the 32-speed BLT and improve the working condition adaptability of the 32-speed BLT.Finally,in order to ensure the shift quality of the 32-speed BLT,aiming at the working characteristic of the multiple planetary rows operating together in the 32-speed BLT,the power-on upshift and downshift process control strategies of the clutch to clutch and multi-clutch to multi-clutch are designed.Through the dynamics analysis of the shift process of the 32-speed BLT,the generation mechanism of shift jerk is determined.The equivalent two-speed model of each planetary row is built,which is used to simplify the shift process of each degree of freedom.For the shift process of two degrees of freedom,the torque phase and speed phase control strategies of open loop and closed loop are designed,and the robustness of controller is enhanced by using the fuzzy adaptive PID control algorithm in closed-loop control of the speed phase.Based on the shift process control of two degrees of freedom,the time-synchronized shift sequence control strategy is proposed for the shift process of multiple degrees of freedom,which ensures that the transmission ratio changes accurately and smoothly during the shift process of multiple degrees of freedom.The effectiveness of the shift control strategies in this thesis is verified by the test of the power-on upshift and downshift process of each degree of freedom,and the 32-speed BLT is guaranteed to have good shift quality.The research on the shift control strategy of the 32-speed BLT carried out in this thesis has certain theoretical guiding significance for the actual development of BLT,and provides a reference for the shift control strategy design of similar multi-speed automatic transmissions.