Research On Vibration Characteristic Analysis And Gear Modification Of Main Reducer Gear System Of 6AT Tranmission

As the main component of the car,the vibration noise of the transmission is closely related to the NVH performance of the whole vehicle,so it is necessary to study the NVH performance of the transmission.With the rapid development of transmission technology,the traditional three-axis transmission has been gradually eliminated from the market,AT transmission has become the first choice of consumers,in the high-grade AT transmission localization process,a large number of studies show that the vibration of the main gear reduction system located under the transmission is the main cause of transmission noise.In order to improve the NVH performance of AT transmissions,the solution adopted by major automobile manufacturers is to improve the processing accuracy of the main gear reduction gear set,but this method will significantly increase the production cost of transmissions,so major manufacturers are constantly looking for other solutions for AT transmission vibration reduction and noise reduction.In view of this,this paper takes the domestic 6AT transmission as the research object,studies the generation mechanism and action mode of dynamic excitation of the main reduction gear set in the meshing process,establishes the full-degree-of-freedom nonlinear dynamics model of the transmission system where the main reduction gear set is located,and calculates the dynamic characteristics of the main reduction gear system based on this model.The vibration amplitude of the main reducer gear system is reduced by means of comprehensive modification of gear.The main research contents are as follows:Firstly,analyzing the internal and external excitations that affect the gear drive.This paper mainly analyzes the mechanism and mode of action of the stiffness excitation of the main reducation gear set inside the 6AT transmission,studies the calculation method of meshing stiffness,solves the meshing stiffness of the main reducation gear set by the meshing line substitution method,analyzes the influence law of different parameters on the meshing stiffness,studies the mechanism and calculation method of other excitations,and lays the foundation for the establishment of the dynamic equation of the main reducation gear system.Secondly,the nonlinear dynamics model of the main reducation gear system is established,and the dynamic characteristics of the system under different operating conditions are analyzed.This paper analyzes the force of the teeth in the transmission process of the main reducation gear set,considers 6 degrees of freedom at each node,establishes the multi-body time-change dynamics equation of gear-axis-bearing coupling,solves the equation by using the numerical solver in MATLAB,obtains the vibration characteristic curve of the main reducation gear system,studies the influence of speed,tooth side gap and rodent stiffness fluctuation range on the vibration characteristics of the main reducation gear system.Thirdly,in order to improve the NVH performance of the 6AT transmission,the main reducation gear set is comprehensively repaired.The profile equation of the main reducation gear set after the trim is established,with the minimum load distribution density and the least error on the meshing line as the trim target,the optimal trim parameters are solved by multi-objective optimization genetic algorithm,the finite elements are analyzed on the main reducation gear set before and after the trim,and the positive stress size,load distribution and gear meshing stiffness change law before and after the gear repair are obtained.The effectiveness of gear trims in improving vibration noise in the main and reducation gear system is verified.Finally,building a test platform to conduct test research on 6AT tranmission.Based on a domestic 6AT transmission as the research object,the vibration signal and noise signal measured in the test are analyzed,the correctness of the above theory is verified,and the vibration noise level of the 6AT transmission before and after the repair is compared,it is proved that the gear trim can effectively improve the NVH performance of the 6AT transmission.