Research On Variable Speed Pump-controlled Three-chamber Cylinder System And Application In Excavator

The hydraulic system has the advantages of high power density,long service life and flexible layout.It is widely used in automation equipment and heavy machinery in the industrial field.This paper aims to focus on the goal of energy-saving and efficient operation of the hydraulic system,propose a new variable speed pump-controlled threechamber hydraulic cylinder system.In the meantime,a speed feedforward-fuzzy PID compound controller was designed.Finally,it were applied to the boom of hydraulic excavator.The paper mainly conducts research in the following four aspects:(1)Firstly,the operating principle of variable speed pump-controlled system is analyzed,the structure design and finite element analysis of the three-chamber hydraulic cylinder are carried out simultaneously.The variable-speed pump control three-chamber hydraulic cylinder system is proposed by using variable-speed quantitative pump as the power source,and the system operating conditions and system energy transmission chain are analyzed.(2)Then the mathematical model of variable speed pump-controlled differential cylinder system was established in MATLAB/Simulink,and the correctness of the model is verified by the experimental data.On this basis,the simulation model of variable speed pump-controlled three-chamber hydraulic cylinder system was established,which was preliminarily applied to the excavator arm,and the operating characteristics of the differential cylinder system and the three-chamber cylinder system were compared.The parameters of the boom accumulator in the three-chamber cylinder system are optimized and analyzed.(3)The speed feedforward and fuzzy PID compound controller were designed,and the operation of the variable speed pump-controlled three-chamber hydraulic cylinder system was compared and analyzed under different control strategies.The results show that the response time and overshoot of the variable speed feedforward and fuzzy PID position feedback compound control strategy are reduced by 41% and 54% compared with PID control,which has good position tracking performance.(4)The multi-body dynamics model of micro-hydraulic excavator was established in MATLAB,and the hydraulic system of three-chamber hydraulic cylinder controlled by variable speed pump was applied to the excavator arm.The speed feedforward fuzzy PID control strategy is used to control its position.The results show that the relative error rate of position can be controlled at 3% under a typical cycle condition.Compared with the variable speed pump-controlled differential cylinder system,the peak power of the system is reduced by 25.12% and the energy saving is33.11%,and the operating efficiency of the system is increased by nearly 8%.