Analysis And Energy Saving Research On The Slewing System Of Large Hydraulic Excavator

With the rapid development of the national economy,more and more infrastructure needs to be improved,which caused the sales of hydraulic excavator continuing to increase.Hydraulic system used in hydraulic excavator enjoys a low energy consumption and thus has great energy saving potential.During the working process of excavator,the rotary mechanism requires to be started and braked in a frequent way in order to complete the work.Therefore,researching the energy of excavator produced during its rotary and brake process is beneficial to improve the whole machine energy,reducing energy consumption and heating problems.This study is based on 70 t hydraulic excavator,whose hydraulic system is negative flow control.This paper mainly analyzes the dynamic characteristics and energy loss of the rotary hydraulic system,and conducts energy-saving research on the rotary system.The main contents are as follows:(1)Analysis of negative flow control rotary hydraulic system and design of rotary energy saving hydraulic system.Firstly,the structure and working principle of negative flow control slewing system of traditional large-scale hydraulic excavator are described,and its energy loss form is analyzed.Secondly,according to the design principle of energy-saving hydraulic system,aiming at the energy loss of the system,this paper puts forward a scheme of energy-saving rotary hydraulic system which combines the recovery of braking energy by accumulator and the separate control of actuator ports.(2)Simulation analysis of load characteristics and energy consumption of negative flow control rotary hydraulic system.The three-dimensional model of the excavator actuator is built by Pro.E.The influence of the position change on the moment of inertia of the rotation center is analyzed in ADAMS software,and the maximum moment of inertia under full load condition is obtained.The simulation model of negative flow control of rotary hydraulic system is built in AMESim software.Based on the model,the influence of moment of inertia and displacement of hydraulic motor on the characteristics of rotary starting and braking is analyzed,and the energy loss and recoverable energy of the system are quantified.(3)Key components selection and mathematical modeling analysis of rotary energy-saving hydraulic system.The parameters of the accumulator and the parallel oil return control valve are calculated and selected,and the control strategy block diagram of the accumulator is built.By establishing the transfer function of thedynamic characteristics of the rotary system,the main parameters affecting the operation of the return hydraulic system are analyzed.(4)Simulation analysis of rotary energy-saving hydraulic system.Using AMESim to build a simulation model of a rotary energy-saving hydraulic system,the energy-saving effect of the new rotary hydraulic system was verified by analyzing the pressure of the system and the energy curve recovered and released by the accumulator,and the factors affecting the recovery efficiency of the accumulator were simulated.The research results show that,under the same control signal,the simulated data and experimental data of single actions are basically the same,verifying the correctness of model established.Furthermore,the comparison between the flow regeneration loop and the original system shows the boom can go down separately by its dead weight,the parallel oil return control valve can realize the independent control of the inlet and outlet of the hydraulic motor,reduce the oil return throttling loss and make full use of the negative flow control to reduce the start-up overflow loss.Using the accumulator to recover the upper brake overflow during the rotary braking.Comprehensive analysis of energy consumption of rotary system and energy recovered and reused by accumulator shows that the energy saving rate of rotary energy saving hydraulic system is 17.13%.