Study On The Mechanism And Control Of Uninterrupted Shift Transmission

Uninterrupted shift transmission (UST) is a novel vehicle transmission concept withoriginal innovation and proprietary intellectual property rights. UST is based on the matureparallel shaft-gear technology, and replaces the dual clutch assembly in dual clutchtransmission (DCT) with the dual controllable one-way clutch based multimode controlledshifter (MCS) assembly. UST realizes torque uninterrupted shift by controlling dual MCSmodes and synchronizers. The shift process of UST not only overcomes the inhered torqueinterrupt drawback of automated manual transmission (AMT), but also avoids the preciseclutch-clutch overlapping control of both planetary-automatic transmission (AT) and DCT.Since UST has adopted the similar basic structure to AMT and DCT, which meanskeeping the same or adopting the similar layout, parts and assemblies. As a parallel shaft-geartransmission, UST owns the well technical and production basis.In this dissertation,the operating method, dynamic shift characteristics, shift controlstrategies and shift quality optimization of the novel transmission UST are deeply investigatedthrough theoretical, simulation and experimental means. The main research work is asfollows:Starting with the working principle and characteristics of MCS, the material technicalblue print of UST driveline is studied. The kinematic characteristics of dual MCS assemblyare analyzed. Based on the switch of MCS working modes, the UST shift principles andoperating methods of dual MCS for diversified vehicle working conditions are elucidated.UST functional prototype is developed, UST bench experiment system is constructedand UST shift functional experiments are carried out. The experiment results show that USThas realized the designed function of torque uninterrupted shift.The engine dynamic torque model has been established based on the experiment data,and MCS dynamic model has been established. The UST driveline system model includingdynamic models of engine, clutch, transmission and vehicle has been established. The shiftschedules for both the normal performance and fuel economy have been designed based onengine fuel map data and vehicle parameters. The simulation control model for UST vehicleshas been built up on Matlab/Simulink software, which provides foundation for theoretical analysis on UST shift characteristics and simulation study on UST vehicle performance. Thesimulation of UST vehicle performance has been carried out.Considering the shift shocks appeared in results of UST shift functional experiment andvehicle performance simulation, the idiographic dynamic characteristics of UST shift processare investigated. Aiming at different causes of UST upshift shocks and downshift shocks,UST upshift control strategy and downshift control strategy have been designed and appliedin the simulation model and the experiment system respectively. By the comparation andanalysis of the different simulation and experiment results, the designed UST upshift anddownshift control strategies have been validated effective to solve the shift shock problem.The estimating index of UST shift quality, which includes indexes of shift smoothnessand clutch abrasion, is proposed. Aiming at the weakness of UST upshift control strategy, theUST upshift optimized control strategy has been designed to reduce clutch abrasion by powersource assist in the clutch slipping process. For the optimization of UST shift qualityestimating index, the relative control parameters are solved by intelligent optimizationmethods. The proposed optimized control strategy and solved parameters are applied in USTexperiment system, and the validity of the strategy and parameters optimization methods havebeen demonstrated experimentally.Theoretical, simulation and experimental methods are all used in the dissertation toinvestigate the operating method, dynamic shift characteristics, shift control strategies andshift quality optimization of UST. The theoretical, simulation and experimental results arehighly agreeable with each other, which provides theoretical foundation and technicalguidance for UST product development and future application in vehicles.