| In recent years,the domestic market of multi-purpose truck has great potential for development.With the higher requirements of comfort and safety for multi-purpose trucks,people pay much attention to the NVH performance.The torsional vibration of the transmission system is an important source of vibration and noise of the car,which affect the NVH performance of the entire vehicle.In this paper,the multi-purpose truck is taken as the research object,and the research on the torsional vibration of the transmission system is carried out by means of modeling simulation and experimental verification.The main research contents are as follows:(1)Combining with the structural characteristics of transmission system of the vehicle,the transmission system of vehicle is simplified to a 12 degrees of freedom transmission torsional vibration system by using the concentrated mass method;the moment of inertia,torsional stiffness and damping parameters of the transmission components are obtained,and then equivalent parameters of each component are determined according to the principle of quantification;the dynamic equation of torsional vibration system under free vibration and forced vibration are established.(2)The model of torsional vibration of transmission system for free vibration and forced vibration are established in AMESim.The natural frequencies and vibration modes are obtained by the free vibration analysis on the model.The measured speed of engine is used as the excitation to obtain the characteristics of forced vibration.The results show that the fifth-order natural frequency of the transmission system falls in the common speed range of the engine,and the second-order excitation of the engine is the cause of the torsional vibration of the transmission system.(3)The speed sensor and the acceleration sensor are installed on the test vehicle,the vehicle test was carried out,data was collected through the LMS Test.Lab system and the vehicle torsional vibration was analyzed.The results show that the natural frequency of the transmission system and resonance speed error obtained by simulation and experiment are small,and the overall vibration trend of the second-order curve of simulation and test is consistent.The model built in this paper can be used to study the torsional vibration of the transmission system.(4)The influence of transmission shaft parameters,half-axis parameters,main reduction ratio and load of tail box on torsional vibration is studied by Using the established simulation model.It is found that the inertia of transmission shaft,the stiffness of half-shaft and main reduction ratio have a great influence on the resonance speed and the tail box load has a great influence on the the amplitude of the torsional vibration.(5)According to the torsional vibration problem of the transmission system for the original test vehicle,the optimization scheme of torsional vibration damper of clutch is adopted,and the parameters of main damping level of the torsional vibration damper are matched and simulated in AMESim,and the influence law of the parameters of the main damper on torsional vibration are obtained,and the parameters optimized of the main damper of the torsional vibration damper are determined.The vehicle test results show that the scheme can effectively reduce response amplitude of the torsional vibration. |
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