| The large hydraulic excavators are characterized by large working weight,high installed power,poor working environment,and huge energy consumption.They are mainly used for the open-pit mining and major infrastructure project.The average efficiency of the hydraulic system,applied in the large excavator,can only reach 30%~40%.As the efficiency is a very low value,there is a huge energy saving potential.Based on the above actuality,a comprehensive study on the essential design and energy saving technologies of the machinery,electricity,and hydraulic control system of large mining hydraulic excavators is carried out.Based on the current situation that the 15 m3hydraulic excavator lack design basis,the simulation design of the machinery,electricity,and hydraulic control system of the 15 m3hydraulic excavator,is carried out by machinery,electricity and hydraulic joint simulation virtual prototype model.The machinery,electricity and hydraulic control system of the large excavator,including the working device,swing system and walking system,is designed.Its operating performance is comprehensively analyzed.The physical prototype of the 15 m3hydraulic excavator is designed and manufactured,and then tested.The experimental results are analyzed and compared with the simulation results and the modeling and simulation deviation of virtual prototype is obtained.The research comprehensively analyzes the research and design problems of large hydraulic excavator by experiment and simulation.Based on this,the idea of meter-in and meter-out independent control is introduced into the hydraulic control system of large hydraulic excavator.A test platform of meter-in and meter-out independent control system is established on a 6-ton hydraulic excavator.On the basis of the platform,the control strategy and energy saving effect of the hydraulic system of meter-in and meter-out independent control are analyzed and verified.Based on the comprehensive analysis of meter-in and meter-out independent control system,a meter-in and meter-out independent control system based on negative flow control system is designed for the large hydraulic excavator.This is performed on the platform of the 76-ton hydraulic excavator.For the large hydraulic excavator,the weight of the working device and the starting inertia are very large.Therefore,boom potential energy recovery system based on liquid-gas energy storage balance principle is added to further improve the efficiency of the excavator.Piston accumulator is the key component of the boom potential energy recovery system,which is based on liquid-gas energy storage balance principle,on the platform of 76-ton hydraulic excavator.So a thermodynamic model of accumulator based on multi-physical field coupling method is established.The dynamic pressure distribution,temperature distribution and the motion law of gas inside the gas chamber during the working process of the accumulator are obtained by the model.The model is used to select the appropriate accumulator,and it is verified by the actual equipment.Basis on the design and analysis of 15 m~3 hydraulic excavator and 76-ton hydraulic excavator,the electro-hydraulic control system with meter-in and meter-out independent control and the potential energy recovery system of boom are extended to the design of 20 m~3 hydraulic excavator with larger tonnage,and the system is verified by virtual prototype simulation.The main contributions of this paper are as following:(1)The machinery,electricity,and hydraulic control system of a China's first large mining hydraulic excavator,with the bucket capacity of 15 m3,is designed by virtual prototype technology.(2)A meter-in and meter-out independent control hydraulic system based on the pump-valve compound control is proposed,and the experimental platform is established.The control strategy of the new system is verified by experiments(3)A boom potential energy recovery system based on liquid-gas energy storage balance principle is proposed,and it is applied in a 76-ton hydraulic excavator with the meter-in and meter-out independent control system.(4)The electro-hydraulic control system with meter-in and meter-out independent control and the potential energy recovery system of boom are extended to the design of 20 m~3 hydraulic excavator with larger tonnage,. |
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