| Cylindrical gear is one of the most widely used automotive transmission parts,it has the advantages of high transmission efficiency,high load carrying capacity,reliable work and compact structure.With the rapid development of technology and electric vehicles,the demand for drive axle cylindrical gears working under high speed and heavy load conditions has increased.At the same time,the market has become more and more demanding in terms of gear design and development technology,paying more attention to its vibration and noise performance.In this paper,we take the cylindrical helical gear of electric drive axle as the research object.Based on the finite element contact analysis,this paper obtains the transmission error curve under the influence of the mesh misalignment;and establishes the space beam element dynamic model of the cylindrical gear,analyzing the vibration characteristics and dynamic response of the cylindrical gear system;considering the effect of gear modification on the dynamic performance of the gear system.The effect of gear modification on the dynamic performance of the gear system is investigated in order to compensate for the amount of misalignment caused by the system deformation and reduce the vibration noise under transmission error excitation.The main work of the thesis is as follows:Transmission error is the main source of excitation for the dynamic model of gear systems.Based on the finite element software ABAQUS,a contact analysis of the cylindrical helical gear pair of an electric drive axle is performed.This analysis obtains static transmission error and considerate the amount of misalignment caused by the deformation of the bearing and shaft system under load.Comparing the gear transmission error curves under the two scenarios with or without considering the effect of misalignment,the meshing misalignment is found to increase the peak-to-peak value of the transmission error.The space beam element dynamic model of involute cylindrical gear is established,and the natural frequency of the cylindrical gear are calculated by modal analysis.The frequency response of the gear system under the excitation of one unit of harmonic transmission error is calculated based on the modal superposition method,and the dynamic response of the cylindrical gear of the electric drive axle under the peak frequency is studied.The static transmission error is expanded into the form of a multi-order harmonic function,and the time domain steady state displacement response of the system is calculated.In order to verify the correctness of the calculation method and programming,the above calculation results are compared with the modal analysis,harmonic response analysis and transient dynamics analysis results in ANSYS respectively.The results show that the dynamic modeling method in this paper is accurate and efficient.Based on the dynamic modeling method proposed in this paper,the root mean square values of the dynamic meshing force under multi-order harmonic transmission error excitation are calculated,and the dynamic meshing force curves at different meshing frequencies are finally obtained.The effects of considering multi-order and single-order harmonic transmission error excitation on the dynamic meshing force curves are compared and analyzed.The results show that the trends of the two curves are the same overall,and when the influence of the multi-order harmonic component is considered,the peak dynamic meshing force increases and the dynamic performance deteriorates.The effects of tooth profile modification and tooth direct modification on static transmission error and dynamic meshing force are compared and analyzed.The results show that appropriate modification parameters can not only reduce the peak value of transmission error,but also make the transmission error curve smoother.Reasonable modification parameters can effectively reduce the amplitude of dynamic meshing force,thus weakening the vibration and noise of the system. |
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