Development Of Durability Test Bench For Gear Shift Assembly Of Transmission

The driving conditions of automobile are complicated and changeable,which makes frequent shift.According to statistics,during working life of automobile,the numbers of shift are hundreds of thousands.Therefore,it is necessary to study fatigue durability of shifting mechanism of manual transmission.Gear shift assembly is the key component of the shifting mechanism and it can select and shift gear.Developing a durability test bench to detect the fatigue life of gear shift assembly can provide reliable fatigue life data for the design and reduce the research cost and ensure the production quality,so it has great application prospect.Based on the analysis of the fatigue durability testing technology of automobile transmission at home and abroad,this paper designs the durability test bench for gear shift assembly and develops the measurement and control system of it.The main research work in this paper can be summarized as follows:(1)The work principle of shift process of manual transmission is analyzed,and then the work principle of gear shift assembly is studied.It mainly analyzes the motion law of the gear select process and shift process of gear shift assembly and draws the torque-angle theoretical curves of it.The above research provides a basis for structural design of the durability test bench.(2)According to the design requirements and the standard of testing method for auto manual transmission assembly,the servo motor with better motion characteristics and dynamic characteristics was chosen as the power source.Based on motion principle and structure characteristic of the gear shift assembly,a durability test bench is designed and constructed,including the tank with fixture and loads,the manipulator of gear shift,the manipulator of gear select,the external frames,etc.(3)Parametric model of key parts of the durability test bench for gear shift assembly is established by ANSYS software.Considering the real working condition of the key parts,we carry on the static analysis.And then,the modal analysis is carried out by Lanczos method,and natural frequency and modal is solved.(4)Aiming at force transmission mechanism of the top sheet and force transmission mechanism of the medium sheet,the loading spectrum of fatigue life analysis is acquired.Referring to the GL standard,the material's S-N curve of two kinds of the load-force transferring mechanism is calculated.At last,the fatigue life prediction of two kinds of the load-force transferring mechanism is conducted with ANSYS/ FE-SAFE based on fatigue cumulative damage theory.(5)By controlling the servo motor with the blocks of MAP library instruction of S7-200 PLC.The main control program and subroutine of the slave computer is developed,including manual control,gear position calibration,automatic control,motor driving,data acquisition,condition monitor of gear position.The host computer interface is developed by configuration software.Then the durable experiment of the gear shift assembly is carried out.First,debug the manipulator of gear shift.Second,debug the manipulator of gear select.Finally,the loading curve of the shift process is drawn.