Research On Multiple Hydro-mechanical Continuously Variable Transmission Patterned After DCT

Multiple clutch system has been attracting wide attention since it can achieve non-impact shift.Being a special case of the multiple clutch system,dual clutch transmission(DCT)is more compact and can also achieve non-impact shift while the shifting progress is extremely short.However,the existence of the simultaneous sliding friction of two clutches during the shifting progress causes a serious clutch ware.Hydro-mechanical continuously variable transmission(HMCVT)being formed by parallel connecting mechanical transmission path and hydraulic transmission path has large transmitting ratio and the capability to transmit large torque and simulate the clutch without clutch ware.Multiple Hydro-mechanical continuously variable transmission(MHMCVT)witch is composed of two HMCVT systems can achieve the non-impact shift theoretically by simulating the DCT system without serious ware.Therefore,we have studied the power shifting progress of the MHMCVT system taking the high-power tractor with power shifting transmission as the target model.The main jobs are as follows:(1)Taking the difficulty of achieving the function of clutch as the criterion for judgement,the advantages and disadvantages between the input coupled HMCVT system and the output coupled HMCVT system have been researched.Basing on the result,the input coupled HMCVT system has been taken as the subsystem of MHMCVT.(2)The structure form and the combination form witch is used to combine with the existing power shifting transmission have been determined.(3)The dynamic models of different modules in the system have been built,afterwards,the simulations of each module have been finished.Integrating the submodels,the vehicle dynamic model with MHMCVT system has been built.(4)Basing on the vehicle dynamic model,a kind of low-impact shifting control strategy witch is applicable to the MHMCVT system has been given.(5)In order to facilitate comparison,the multi-state dynamic model of DCT has been built.Afterwards,basing on the mathematical expression of shifting jerk under each state above,the influencing factors of shifting qualities have been analyzed,at the same time,a kind of new shifting control strategy of DCT basing on the regulation of engine speed has been given.(6)Comparing the shifting control strategies between DCT and MHMCVT,the pros and cons of them have been researched.(7)To meet the requirement of the displacement control in MHMCVT system,the model of electro-hydraulic proportional control system has been built.Basing on the fuzzy PID control method,a kind of signal tracking control strategy has been given and simulated.(8)Basing on the Simulink platform,the simulating model of DCT has been built,basing on the co-simulating technique between AMEsim and Simulink platform,the simulating model of MHMCVT has been built too.After analyzing the results of simulation,the theoretical analysis is verified.