| With the rapid development of the construction machinery industry,automatic transmission is widely used in rail transportation,mining machinery and other areas.Multi-row planetary gear train system is a key component of automatic transmission,a direct impact on the performance of the transmission.This topic comes from the production practice of the enterprise.Though the multi-row planetary gear train system structure of automatic transmission is complex,the traditional design methods are mainly adopted in the current development of new products in which in order to ensure the realization of new product features,the design is usually a larger safety factor,resulting in big appearance size and heavy weight of products,which cannot meet the low-cost products,lightweight.In this paper,the planetary gear system of AT-series automatic transmission is used as the research object.The main research of this subject is as follows:Based on the 3D modeling of the planetary gear train,the parametric solid model of the planetary gear transmission system is established by using the modern design method and means such as CAD technology and virtual prototyping technology,and the virtual assembly of the multi-row planetary gear train is completed,which can not only realize the 3D modeling and virtual assembly of the planetary gear transmission system in the new product development,but also lay the foundation of the static and dynamic characteristics for the planetary wheel.Through the analysis of the meshing process and the force of the involute helical cylindrical gears,the time-varying meshing stiffness expression of the gear meshing is obtained.The main excitation of the two planetary gears is excited by the time-varying meshing stiffness and the bearing stiffness,establishing the dynamic model of planetary gear train.Based on the amount of interference between the planetary axle and the shaft hole on the planet carrier,the experiment design and the finite element simulation experiment are carried out to analyze the relationship between the interference amount and the stress and deformation.Under the premise of meeting the requirements of the planetary strength and stiffness design criteria and the manufacturing process,the reasonable range of the interference value is gained,which provides the basis for the structural size design of the planetary gear train.Based on the finite element analysis of the planetary carrier,the sensitive parameters affecting the mass and stress distribution of the planetary carrier are selected as the optimized variables.With the small structural deformation and the light weight as the optimized target,the multi-objective optimization of the planetary frame carried out,the corresponding optimized parameters are gained.The modal analysis is carried out on the planetary carrier and the first 6 order modes are extracted.Comparing the first order frequency with the operating frequency can avoid the resonance of the planetary carrier under various operating conditions.Taking the fourth gear of the transmission as an example,the planetary gear train is used as the research object.And the static contact analysis and dynamic contact analysis of the sun gear,the planetary wheel and the ring gear are carried out from the contact stress.Considering the actual structure and working condition of the planetary gear,in the analysis of the train wheel,the flexible finite element analysis model of the sun gear is established.The sun gear is used as the flexible body and the other components are rigid and flexible coupling analysis of the rigid body,which gains the time-varying curve of contact force of tooth surface and the time-varying curve of speed and acceleration of planetary frame output part.The above research work provides a basis for the structural analysis of the planetary gear train,the analysis and prediction of the dynamic characteristics of the gear meshing,the failure analysis of the planetary gear train and the optimization of the parameters in the product design and development stage,besides It provides a technical reference for enterprises to establish independent innovation design system. |
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