Schematic Design And Performance Analysis Of Planetary Gear Transmission For Automatic Transmission

Planetary gear mechanism is widely used in automatic transmission because of its compact structure,large transmission power,smooth transmission and so on.Foreign motor companies have blocked the technology of automatic transmission,which has prevented the production of automobile automatic transmission in our country.In order to change the backward situation,we must research on automatic transmission independently.In our country,relevant design theory about automatic transmission is not perfect.It is of great significance to research on schematic design,efficiency and dynamic analysis of planetary gear transmission for automatic transmission.In this paper,graph theory is applied to the synthesis of planetary gear mechanism.Lever analysis method is used for the enumeration of clutching sequences.Kinematic analysis,static force analysis,power flow and efficiency analysis of planetary gear mechanism is completed through computer programs.The dynamic analyses of planetary gear system of 6HP26 type automatic transmission are accomplished.The main research work and achievements are listed as follows:1.The topological graph of planetary gear mechanism is established.This paper has synthesized some topological graphs of two and three DOF planetary gear mechanism.The procedures of isomorphism identification and rigid subchain detection are particularly presented.According to the transformation rules,topological graphs of planetary gear mechanism are converted into standard topological graphs and kinematic diagrams.Some transmission schemes of two planetary rows,three planetary rows and four planetary rows are obtained.2.Lever analysis method is used to enumerate clutching sequences of planetary gear mechanism.Considering the operability,two planetary rows can realize up to four forward gears and one reverse gear;three planetary rows can realize up to six forward gears and two reverse gears.3.Using graph theory,computer aided motion,static force and power flow analysis of planetary gear mechanism is realized.Based on kinematic and static force analysis model,related matrices are acquired.Hence,kinematic and static force analysis of planetary gear mechanism is achieved.The link power can be determined by the link speed and torque.Power flow diagrams of each gear are acquired.The efficiency is calculated by transmission ratio method.The motion,static force and efficiency calculations of 6HP26 automatic transmission are carried out.4.The dynamic analyses of 6HP26 automatic transmission are carried out.Using lumped mass method,the translational-rotational coupling dynamic models of automatic transmission in fifth gear and second gear are established.And the natural frequency and vibration mode of automatic transmission in fifth gear and second gear are obtained.Engine output is taken as an external excitation.Time-varying meshing stiffness and comprehensive meshing error are taken as internal excitations.The dynamic responses of automatic transmission in fifth gear and second gear are researched.Then,this paper has analyzed the effects of system parameters on natural frequency such as component quality,moment of inertia,etc.The analysis results provide a basis for the vibration reduction and dynamic optimization of 6HP26 automatic transmission.5.The pure rotational dynamic model and Simulink model of automatic transmission in first gear are established.Component displacement and accelerated speed response,dynamic meshing force of gear pair of automatic transmission in first gear are acquired through simulation.Dynamic response analyses provide a reference for the vibration reduction of 6HP26 automatic transmission.Finally,some conclusions and observations are given and the developmental prospects of planetary gear mechanism for automatic transmission are discussed and outlined.