Study Of Shift Force Characteristic Simulation On The Gear Box Operating Mechanism Of A Commercial Vehicle

Gear shift quality of auto has been more concerned by consumers nowadays, as thedevelopment of automobile industry. Evaluation of Gear shift quality are being researchedby many institutions, it involves the driver’s subjective feeling, such as shift force, handfeeling and Comfort while shifting. However more and more studies are carried to try toanalyze and evaluate the shift quality through simulation and experimental data, and thegear shifting force-displacement curve is one of the most important macroscopicquantities, which reflects the gear shifting performance. So this Master’s Thesis try to dealwith the study of mechanics characteristics of gear box operating mechanism bases on thegear shifting force-displacement curve.Synchronizer mechanisms allow gear changing in a smooth way with less vibrationsand impacts, it also improves the durability of the transmission and the shift comfort ofdrivers. Synchronizer is so important for the gear shifting that it is the key studying part ofthis thesis.The thesis is based on a project between the FAW-RDC center and Jilin University,which is about the analysis and research of gear shift performance of the commercialVehicles. Firstly, analyzing the structure and working principle of gear shift system andraveling out the shift force transfer path should be done. Then a dynamic model of gearsshift system on MT is built by AMESim, on the other hands, static rig test and dynamic testare carried. Comparing simulated and experimental results, it is founded that simulation andexperiment have good consistency. Finally the dynamic model can be used for furtheranalysis of the factors influencing the gear shift quality. The results show that the biggestshift force occurs in the synchronization stage, in which sleeve chamfers contact ringchamfers. The other components such as self-locking mechanism and strut detent make little contributions to the biggest shift force. Though the double bump comes up with somerandomness, it still can be improved. Shift cable and self-locking mechanism bothcontribute to lower the double bump. Besides,the outline of the self-locking slot makes adifference to gearshift inhalation feeling.Shift quality gets more and more attention by customers, this thesis try to study theessence of gear shift problem through simulation, it would do some help in improving thegear shift quality of vehicles.