Research On Shitf Performance For Transmission Based On AMESim Of Loaders

Loader, as a kind of construction machinery, is widely applied to highways,mines, ports and many other fields. The gearbox is one of important parts of thewhole transmission system of the loader, the security and reality of the loader areinfluenced by its shift performance significantly. Stability is an objective standardevaluation of the shift performance of loader. Due to the incompressibility of liquidand the bigger stiffness of hydraulic system in the shift process, the shift shock whichis significant impacts on the driving security and comfort will occurred whencombined component contacted excessively. Hence, improving the shift smoothnessand reducing the shift shock is the key point for the improvement of shift performanceand also is the research purpose of this paper.The article of this paper comes from the school-enterprise cooperation projectwhich is called “research on dynamic simulation analysis and comparison tests of theloader’s hydraulic system and transmission system”. Based on the current shift shockphenomenon existed in the working process of the loader, in order to analyze andresearch the shift performance of the loader’s transmission system deeply, this papersimulates and analyzes the system model which is established by AMESim software,and then verifies the conclusion combined the experiments while uses thetransmission system of the wheel loader as the research object.In this paper, the loader’s variable speed system is introduced on theclassification of the gearbox and the shift operation method which is commonly used.Then, the transmission part of variable speed system and the structure and workingtheory of control system are analyzed separately. And the shift performance of thegearbox has been researched after the presentation of the existing shift chockphenomenon. With the wheel loader’s gearbox system which is controlled by thefixed axis electric-hydraulic control system is treated as the research object, thedynamic and kinematic analysis of the gearbox’s shifting process is finished, and the mathematical model of regulating valve is also established and analyzed based on thetransfer function method. The models of gearbox transmission system and controlsystem are built by AMESim software. In order to analyze the shift performance ofthe gearbox effectively and deeply, the model of electric-hydraulic control part is builtby both system model and HCD library model. After the in-depth simulation resultsanalysis, especially the pressure changes analysis for the shift clutch in multi-angle,the existing shift shock problem of the gearbox is clarified. To determine the impacton gearbox’s shift performance caused by several parameters of clutch and controlsystem, compared with all the other structural parameters of the clutch, the diameterand maximum travel distance of the piston are finally determined as two factors thathave the maximum impacts on shifting after various factors are simulated andanalyzed in single series, and compared with all the other structural parameters ofpressure regulating valve in the electric-hydraulic control system, the buffer springstiffness and orifice’s size are finally determined as two factors that have themaximum impacts on shift performance. Finally, the accuracy of the model is verifiedafter the experiment curve and simulation result have been compared with each other,and corresponding improvements to enhance the shift smoothness of the loader havebeen proposed.