| Hydraulic excavator as a commonl used multi-purpose construction machinery,play an important role in the earthwork construction process.However,as its operating system belongs to the valve-controlled open hydraulic system,a large amount of energy will be lost at the valve orifice in the form of throttling and overflow in the working process,resulting in waste of energy and system heating.The pump control closed system can effectively reduce the throttling loss due to the elimination of valve control elements such as multi-way valves.While completing the functions of the valve control system,it can also take into account the advantages of integration of driving and energy recovery.Therefore,in order to reduce the problem of large energy consumption in the valve-controlled hydraulic system of excavator,this paper applies the pump-controlled closed system to the hydraulic system of excavator for energy saving analysis.Due to hydraulic excavator mainly using single rod hydraulic cylinder to work,if using ordinary axisymmetric plunger pump pump closed control system,need to add the assist device in the system to balance single rod hydraulic cylinder due to two different cavity area of flow asymmetry problems,to some extent this cause system complex,rising costs,the oil after auxiliary system balance energy utilization rate is also reduced.In view of the above problems,this paper based on the method of asymmetrical pump balancing the flow difference of the single rod hydraulic cylinder,transformed this method on the original valve controlled hydraulic system of excavator to form a new excavator pump controlled hydraulic system.The relevant characteristics and energy consumption of the two systems were analyzed and compared.The specific research contents are as follows:Firstly,according to the flow distribution theory of the asymmetric axial piston pump,the simulation model of asymmetric pump is built in AMESim simulation software,and the characteristics of displacement,flow and pressure of asymmetric pump are simulated and analyzed to verify the correctness of the piston pump model.Secondly,according to the actual parameters of the working device of a small excavator,the boom,arm and bucket models of the excavator are established in the Solidworks 3d modeling software,and the key data of the 3d model are collected and imported into the AMESim software to establish the multi-body dynamics simulation model of the working device of the excavator.Then,the load sensitive valve-controlled hydraulic system and the asymmetric pumped-controlled hydraulic system after transformation of the excavator are respectively established in the AMESim software,and the corresponding connection is made with the previously established working device model to build a mechanical and hydraulic integrated simulation model of the excavator's valve control system before reconstruction and the pump control system after reconstruction.Finally,two kinds of working cycles and three kinds of loads are specified,the valve control system and pump control system of excavator are simulated and analyzed respectively under the same working conditions.Through the simulation analysis,it can be seen that under the same working conditions,compared with the load sensitive open valve-controlled hydraulic system of the excavator,the asymmetric closed pump control hydraulic system can complete the same operating tasks as the valve-controlled system.The asymmetric pump control system can not only balance the two-cavity flow of the hydraulic cylinder,but also keep the system running more stable and the energy-saving effect is remarkable. |
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