Energy-saving Study Of Working Device Hydraulic System Of Loader

With the rapid development of industry, the problem of energy shortage is on the rise.Loaders often have the problem of excessively high oil temperature.Too high oil temperature of hydraulic will cause many failures with the result that the operation of loader is not flexible,the lifting and turning of bucket is difficult and the working pressure of hydraulic becomes reduced and so on,which have gradually become the object of common concern.At present,the hydraulic system of domestic loader is driven by the fixed displacement pump,when the engine speed is fixed,the flow rate of fixed displacement pump remains unchanged.And the load of loader changes frequently and varies greatly,which may result in much overflow loss of the hydraulic system of loader.The hydraulic system of loader driven by the fixed displacement pump will be replaced gradually by energy-saving hydraulic system,which is a tendency.This paper applies load-sensing variable pump to the hydraulic system of loader considering the matching of pump and the load.Taking the 856â…¢wheel loader as an example,focusing on the energy-saving characteristic and controllability of the hydraulic system of loader,this paper mainly does some theoretical analysis and co-simulation.The main work is summarized as below:Firstly,taking the 856â…¢wheel loader as representation,this paper analyses the power loss of the existing working device hydraulic system of loader during the course of different operating conditions.The result indicates that the output pressure and flow rate of the fixed displacement pump can not change according to the load.The existing working device hydraulic system of loader has much overflow loss, unloading loss and throttling loss.Secondly,for reducing the overflow loss,unloading loss and throttling loss of the existing working device hydraulic system of loader,this paper designs the load-sensing working device hydraulic system of loader according to the design task and the main technical parameters of 856â…¢wheel loader.Thirdly,this paper establishes a mathematical model for the load-sensing working device hydraulic system of loader with the power bond method,which provides a basis for the AMEsim simulation model of the load-sensing working device hydraulic system of loader.Fourthly,when loader is moving,the state of motion and speed are constantly changing which cause the torque arms of the load force and the working device's gravity are also constantly changing,leading to the load force of the hydraulic system that is exerted on the hydraulic cylinders constantly changing. Therefore, it is necessary that we simulate dynamic characteristics of the loader with the co-simulation method with AMESim and ADAMS.This paper establishes AMESim simulation models for the working device load-sensing hydraulic system of loader and its main components.The principles of the main components are analyzed,and the static and dynamic characteristics of the main components are analyzed,and then the static and dynamic characteristics are compared between the results of simulation and the results provided by sample,the results show that the AMESim simulation models of the main components are right.Fifthly,this paper does some dynamic simulation analysis for the loader working device with the software ADAMS.First of all,based on the actual size,the three-dimensional models of components of the loader working device are built with Pro/E,and are assembled according to the actual connecting situation.Secondly,the three-dimensional model of loader working device is passed to the dynamics simulation software ADAMS,and then add the constraint and the load force for the ADAMS model of the loader working device in order to analysis the force that being exerted on boom cylinder and bucket cylinder during the course of different operating conditions.Sixthly,this paper views AMESim model of the working device hydraulic system of loader as the main body,and passes ADAMS model of the working device to AMESim model,and then establishes the co-simulation models for the existing working device hydraulic system of loader and the load-sensing working device hydraulic system of loader.The main parameters of the load-sensing working device hydraulic system of loader are simulated and analyzed,and the power losses are compared between the existing working device hydraulic system of loader and the load-sensing working device hydraulic system of loader with the co-simulation models.Finally,for verify the correctness of co-simulation models,the paper compares the simulated results and the theoretical results.The simulation results show that the load-sensing working device hydraulic system of loader can provide the output pressure and flow rate according to the needs of the load.The load-sensing working device hydraulic system of loader has less throttling loss and is more energy-efficient.