Simulation Analysis And Optimization Of Lubrication Pipe Network Of Loader Power Shift Transmission

The fixed-shaft power shift transmission is an important part of the loader transmission system.The important foundation for its reliable and stable operation is good lubrication.The most important thing for good lubrication is to accurately supply oil to each lubricating component.Too much lubricant flow will cause energy loss in the system,while too little lubricant flow will cause poor lubrication of the components.Most of the early lubricating oil circuit designs used empirical design and then reversed the design method through experiments.With the development of computer technology,the test process can be omitted in the design process and the CFD simulation results can be used instead of the test results.The entire design process takes a long time,and the designed lubricating oil circuit has low flow distribution accuracy and poor reliability.Therefore,this paper uses a combination of computational fluid dynamics and exploration and optimization algorithms to develop an optimized software platform based on Isight software that can implement automatic CFD simulation and precise distribution of transmission lubricant circuit flow.Accurate flow distribution provides an important reference for the design of the lubrication circuit of various mechanical devices.Firstly,a three-dimensional model of the gearbox lubrication pipe network was established,and its meshing and numerical simulation were performed.Considering the accuracy requirements and application range,the SST k-ω model was selected as the turbulence model for numerical simulation,and the SIMPLEC solver was selected to solve the calculation object.Finally,the convergence conditions of the numerical simulation calculation were specified.A flow distribution test bench was designed and constructed to conduct a flow distribution test,which verified the correctness of the CFD simulation results.In order to more accurately and quantitatively analyze the influence of each parameter on the distribution of lubricating oil flow,a theoretical mathematical model of the oil flow distribution is established,and the flow state of the first and third gear oil flow is systematically analyzed.The lubricating oil flow required for each lubricating part of the transmission lubrication pipe network was estimated,and the optimized target flow value was selected.According to the established CFD simulation model of the oil circuit,the effects of operating conditions such as speed and oil viscosity on the distribution characteristics of the lubricating oil circuit are analyzed in detail,and the diameter of the pin hole,the diameter of the oil outlet pipe,and the oil circuit leading to the outlet are analyzed.The influence of structural factors such as length on the flow distribution characteristics of the lubricating oil circuit.Finally,considering the above-mentioned influencing factors,the diameter of the pin hole and the diameter of each branch outlet were selected as design variables for the optimization of flow distribution.Based Isight set up transmission fluid path CFD simulation automation platform to achieve automatic modeling three-dimensional model of the lubricating oil passage,automatic mesh division,Fluent automation parameter settings and other functions,improve the efficiency of subsequent optimization.Combined with the above functions to build the Isight oil circuit flow distribution optimization platform,firstly,the objective function of the lubricating oil circuit is constructed;secondly,based on the sample points selected by the optimal Latin hypercube method and its simulation results,the radial basis neural network model is selected Build a system proxy model to speed up the optimization of the optimization algorithm;then select the multi-island genetic algorithm in the global exploration method as the optimization algorithm to calculate;finally form a complete optimization cycle.After comparison and calculation,it is found that the relative error between the optimized flow value and the target flow value is less than 5%.From the above situation,it can be judged that the results of the first and third gear oil flow distribution optimization are accurate.According to the tree structure of the total lubricating oil circuit,a hierarchical grouping optimization method is proposed to optimize the flow distribution of the total oil circuit of the transmission,and a feasibility analysis of this optimization method is carried out.The optimized results show that the relative error between the flow value of each outlet of the total oil circuit and the expected flow value is less than 8%,which is within the error range.This result confirms the use of stratification for the optimization of the total oil flow distribution of the transmission.The optimization method of grouping is reasonable.