Dynamic Analysis And Modification Optimization Of HMCVT Gear Considering Axial Error

The hydraulic mechanical continuously variable transmission(HMCVT)is an automatic transmission based on the common confluence of the mechanical circuit and the hydraulic circuit,which is controlled by the hydraulic system to realize the stepless adjustment of the input speed of the hydraulic circuit,so that the output speed of the transmission changes with it.Since hydraulic mechancal transmissions are mostly used in high-horsepower tractors,whose output speed and torque change frequently.Therefore,it is necessary to conduct a systematic study on the load of internal gears and other key parts to ensure that the actual meshing quality of the internal gears of the transmission can meet the design requirements of working conditions.In this paper,according to the objectives of the subject,the parameter design and strength check calculation of each pair of gear pairs are completed,so that the strength of the helical gear can meet the requirements of use.On this basis,considering the influence of axial errors that are prevalent in practice,dynamic simulation and modification of the helical gear are processed to evaluate and analyze the strength,the quality and transmission performance.The main research contents are as follows:1.This paper comprehensively considers the scheme and the requirements of the tractor manufacturer to carry out the design and calculation of the transmission ratio of the hydromechanical continuously variable transmission.According to the calculation results of the transmission ratio,the internal rotation speed flow,torque flow,and power flow of the transmission are analyzed,and the triangular power chart analysis method is used to determine the internal circulating power of the three-row planetary gear combiner.According to the judgment of cycle power,speed and torque,the rated speed and rated power of each gear in the transmission are determined.2.According to the determined transmission ratio,use KISSsoft to carry out preliminary design and check of the helical gear.In order to improve the safety factor of the helical gear,reduce the transmission error,reduce the flash temperature,etc.,the precise calculation module of KISSsoft is used to set a certain amount of changes to some parameters of the helical gear and the preliminary optimized helical gear parameters are determined according to the design goals.3.Using the transient impact simulation module in the Workbench software to perform dynamic simulation on the helical gear,it was found that during the speed climbing phase,the contact stress received by the helical gear changes greatly,and the contact stress decreases and stabilizes after the speed is stabilized.The dynamic simulation results of Workbench and KISSsoft are compared.The contact stress obtained by KISSsoft dynamics simulation is slightly lower than the workbench simulation results,but the contact stress distribution points are approximately the same,and the maximum contact stress appears at the top of the tooth.4.Because KISSsoft’s precise calculation of the helical gear transmission ratio has changed,this article uses SimulationX to build a hydromechanical continuously variable transmission simulation model to simulate the output speed continuity of the helical gear.According to the results of SimulationX simulation output,the helical gear ratio after KISSsoft’s fine calculation is still continuous,which meets the requirements of HMCVT continuously variable transmission.5.According to the dynamic simulation results of Workbench and KISSsoft,we know that the gear needs to be modified.It is not meaningful to directly modify the ideal meshing gear.In this paper,the errors that occur in helical gears are classified as axis errors,and the effect of two axis errors on helical gears is studied.The helical gear is modified based on the maximum axis error,and the best modification is obtained by comparing different modification methods.The comparison is made without considering the axis error without modification,the axis error without modification,the axis error without modification,and the axis error without modification.It is concluded that the necessity of considering the axis error when performing gear modification.