Research On Hydrodynamic Transmission System Characteristics And Matching Of Wheel Excavator

The traditional pure mechanical transmission wheel excavator have poor ride stability,short mechanical life and cannot take full advantage of the engine.The working performance and efficiency of hydrodynamic wheel excavator transmission system is greatly influenced by environmental factor.In this paper,a hydrodynamic transmission system is designed for a wheel excavator,and the effective diameter and nominal torque of the circulating circle of the hydrodynamic torque converter are optimized.The hydrodynamic torque converter of wheel excavator is designed and the cascade system of the hydrodynamic torque converter is optimized.Based on MATLAB,the whole machine model is established,the engine and hydrodynamic torque converter are matched reasonably,and the performance of the whole machine is calculated,and the power and economy of the whole vehicle are obtained.The original characteristic curve of the torque converter is obtained through the bench test,which verifies the accuracy of the design of hydrodynamic torque converter.The traction force and maximum speed of each gear are obtained through installation test.The accuracy of the hydrodynamic transmission system design is verified,and the performance requirements of the wheel excavator under driving conditions are satisfied.The main research work and conclusions are as follows.1.In order to meet the performance requirements of wheel excavator under driving conditions,the overall structure scheme of hydrodynamic transmission system of wheel excavator is designed.To achieve a better matching performance,the effective diameter of the torque converter cycle and nominal torque are optimized.There are many parameters affecting the performance of the torque converter.The parameter scheme obtained by the traditional design method may not achieve the best performance of the torque converter,so it is necessary to optimize the parameters to find the optimal parameter scheme.The mean value of the output torque of the torque converter and the fuel consumed by the unit effective are worked as the objective function,the circular circle diameter and the nominal torque are used as the design variables,and the corresponding constraints are given.The optimization function is optimized by using the MATLAB toolbox optimization function.The circular circle of hydrodynamic torque converter of wheel excavator is determined by using the design method of "three arcs".The blades of three impellers of hydrodynamic torque converter of wheel excavator are designed by equal inclination projection method.The three-dimensional model of hydrodynamic torque converter is established by UG,and three impeller channels are extracted for meshing.The hydrodynamic torque converter of wheel excavator is simulated by CFD,and the original characteristics of the hydrodynamic torque converter are obtained.The structure of the second-gear power shift gearbox and the shift hydrodynamic control system are designed.2.The efficiency of the torque converter is used as the objective function of the optimization of the torque converter cascade system.Selecting design variables and giving constraints to meet design requirements.Latin hypercube experiment method was used to select the experimental sample points and the detection sample points.Radial Basis Function(RBF)model was chosen to create the proxy model.NSGA-II non-dominant sorting genetic algorithm was selected to optimize the calculation method.When other parameters meet the constraints,the efficiency of the optimized hydrodynamic torque converter is improved by comparing the efficiency of the optimized hydrodynamic torque converter with that of the optimized hydrodynamic torque converter.3.Based on the powertrain of an 8-ton wheel excavator and the parameters of the whole machine,the mathematical model of the engine and the hydrodynamic torque converter is established.The common working input characteristics and common working output characteristics of the engine and the torque converter are analyzed.The whole machine model is established based on MATLAB,and the performance of the whole machine is calculated.According to the matching characteristics of common work,the traction force of each gear,the maximum speed of each gear,the acceleration time,the gradient of climbing and the fuel consumption of 100 kilometers at the same speed are obtained.4.The original characteristic curve of the torque converter is obtained by bench test.The relative error between the original characteristic curve obtained from the test and the calculated results is less than 5%,which verifies the accuracy of the design of the hydrodynamic torque converter.The maximum traction force and speed of each gear are obtained through the installation test.Compared with the calculated results,the error of traction force and maximum speed is less than 9%,which verifies the correctness of the hydrodynamic transmission system design.