Analysis Of Internal-External Excitation And Vibration Noise For A Loader Transmission

Loader is one of the shovel transport machines,and it is widely used in highway,railway,water resources and hydropower,harbor,mine and other construction projects.In the operational process of loader,extremely poor working environment and the complicated and changeable working mode are the main causes which create vibration of the drive system.As a core part of the drive system,the vibration characteristic and the noise of transmission will influence driving comfort directly.With increased awareness of the environment,noise limit for construction machinery was revised,and the challenge is formed in the vibration and noise reduction of loader.Therefore,it has important significance both in practical directive and engineering application to investigate the structural vibration and sound radiation of loader transmission.This paper takes the loader transmission as research object,and focuses on numerical simulation for inner and outer dynamic excitation of gearing,the analysis of vibration characteristic,prediction of radiated noise and relative tests.The main researches are as follows:(1)Based on the power transmission path of transmission gear system,the output torque excitation of four-stroke single-cylinder and six-cylinder engines is simulated firstly,and then the pure torsion dynamic equation of the converter is established by Newton's second law.Then the oil trapping area of the transmission pump is derived by ANSYS software,and the oil trapping pressure excitation is analyzed.Finally,the multi-body dynamic model of transmission gear system is established in ROMAX.The bearing support stiffness and damping are calculated by mechanical analysis.(2)The single tooth stiffness and synthesizing mesh stiffness of gear pair are calculated by the static contact analysis in ANSYS software.With the consideration of time-varying meshing stiffness and damping,static transfer error,bearing stiffness and damping,motivation of engine,torque converter and variable speed pump,the complex dynamics model of loader transmission is established.By solving these equations,the vibration response of gear system as well as the inner dynamic meshing force of each gear pair is achieved.(3)A parametric mesh model of loader transmission including variable-speed pump is built in ANSYS software.Based on the modal analysis,the vibration response is analyzed by using the mode-superposition method,and vibration displacement,velocity,acceleration are obtained.The vibration test is carried out on the comprehensive performance experimental system,and the test data is compared with the simulation value.(4)In the response analysis foundation,the acoustic boundary element model of the transmission housing is constructed.The surface pressure of gearbox and the radiated noise at field point are obtained by using direct boundary element method in SYSNOISE software.Similarly,the test data of radiated noise is compared with the analysis value.