The Study And Simulation Of Walking Hydraulic Transmission System Of Loader HT25J

As the mature of hydraulic transmission technology, the phenomenon of developing the hydraulic transmission loader becomes more and more popular. Hydraulic transmission loader has many advantages, for instance, its light weight, its smooth and steady work conditions, its low noise and its comfortableness. What’s more, it can realize the stepless speed change.This dissertation is based on the multi-function articulated loader HT25J which is developed through collaboration by HDU studying team and Zhejiang Herotime Machinery Corporation. This dissertation’s purpose is to design the hydraulic walking transmission system and put forward the method to match the system power and control strategy. The main performance of this dissertation is as following:(1) The mechanism system and hydraulic system of the loader’s walking device system was designed. The3D models of the main components of the walking device was builded according to the loader’s features of geometric construction by the software of Pro/Engineer. The hydraulic walking transmission circuit based on the control of variable pump-quantitative motor was designed based on the analysis of different kinds of speed control circuit pressure control circuit and the method of driving motor, and combining the actual operating condition requirement. Derived the transfer functions of open-loop and closed loop of the whole hydraulic walking system by building the mathematical models of each link of hydraulic walking transmission system.(2) The power-torsion-velocity equation of FCCX1125diesel engine was established which was equipped in the loader by analyzing its velocity characteristics, load characteristics and velocity regulation characteristic. Then the conclusion of the optimum working condition was reached according the diesel engine’s curve of velocity regulation feature. Calculate and match the diesel engine and hydraulic system based on the above optimum working condition. Analysis the control program of matching between diesel engine and hydraulic system then validate the final program, and regulate output volume of the hydraulic walking system through electro-hydraulic proportional control(3) The walking and working resistance under different work conditions was analyzed. Then the loader’s traction equation was builded, and the load torsion of driving motor was determined according the traction equation curve and validate the hydraulic system’s work pressure based on the above torsion. By calculating the maximum and minimum work resistance which is matched with hydraulic components, complete the type selection of variable pump and hydraulic motor and then check and verify it. The type of each hydraulic component in each link circuit and validate the corresponding specific parameters was chosen with the aid of results of vehicle dynamics. And the stability of the system was analyzed according to process of drawing the Bode graphics of open-loop transfer function.(4) The theory and design process of the control strategies of conventional PID and fuzzy self-adaptive PID applied in the loader hydraulic walking system was analyzed. The responses to the input signal under this two control strategies and load disturbance signal was simulated based on the hydraulic simulation model. And the results of simulation above was compared, then the hydraulic system’s performance of transient response, stability of system and interference suppression under the conventional PID and fuzzy adaptive-control PID was analyzed.