Research On The Electro-hydraulic Shift Control System Of The Wheel Loader

This article studys the shift control system of the wheel loader. First it introduces the research status of wheel loader’s transmission system-from manual transmission to auto transmission, from shifting by switch valve to shifting by proportional valve and then points to the research object-development of an auto transmission control system based on proportional valve. Secondly, the article talks about the shifting of gearshift control system and bring about one shifting control strategy based on fuzzy control to overcome the disadvantages of traditional shifting. This strategy can automatically calculate the shifting level and best shifting timing according to driver’s operation intent. A new-structured proportional shifting valve is designed and its mathematic model and simulation model are established to be studied theoretically and finally this system goes into bench test and the test result shows that the stress curve and theoretical curve of proportional shifting valve match with each other, and that stable shifting can be achieved, shifting performance improved, and verification plan of the shifting strategy then is proposed. In the end, the article summarizes the results and looks forward to any possible improvements.