Simulation And Experimental Study On Churning Loss Of Gear Pair

In recent years,with the development of new energy vehicles,motor-driven new energy vehicle transmission have become one of the gearboxes developed by transmission companies.As one of the important part of the vehicle transmission system,the gear pair has a decisive influence on the transmission efficiency,power performance and fuel economy of the vehicle.The transmission efficiency is mainly related to the power loss in the gear transmission process.The churning loss of the gear pair is the power loss caused by the resistance force of the gear pair rotating in the oil bath by the lubricating oil.Under high speed and low load conditions the churning loss of the gear pair accounts for an important part of the total power loss of the transmission.However,there are not many in-depth researches on the dynamic energy consumption characteristics of gear pairs at high speeds at home and abroad.The churning loss of gear pair is affected by many factors,including lubricating oil parameters,gear geometry parameters and working parameters.The relationship between the various influencing factors is complex,the solution is very difficult,and the existing empirical formula has a limited scope of application.This topic is based on the research background of the efficiency problem caused by gear churning loss during the high-speed development of new energy vehicle transmission at this stage.In this paper,the moving particle semi-implicit method(MPS)was used to establish a solid-coupling analysis model of gear pair under the influence of multiple factors.Then the analysis model was solved and the simulation results of the gear churning loss were obtained.At the same time,the gear churning loss test bench was designed and built to test the gear pair churning loss and model verification.The multi-factor influence of the gear churning loss and the transient distribution of the lubricating oil was deeply studied.The research results have important engineering guiding significance for the development and optimization of the new energy vehicle transmission.The main research contents and conclusions are as follows:1.The research on the generation mechanism of gear pair churning loss and the key influence parameters were studied.The empirical formulas of churning loss based on a large number of experiments by domestic and foreign scholars were studied in depth,and several typical calculation models of churning loss were obtained.Based on the mechanism of gear pair churning loss,the calculation model of gear pair churning loss was studied,and the calculation models scope of application were compared and analyzed.2.The basic principles and algorithms of the moving particle semi-implicit method were studied.The key parameters such as gear width,helix angle,rotational speed,viscosity and density of lubricating oil,and oil immersion depth were determined.Based on the MPS method,a fluid-solid coupling analysis model was established for the dynamic energy consumption characteristics of gear pairs under the influence of various parameters.The simulation results of one typical example were taken as an example to analyze the lubricating oil in the gearbox at different speeds.The transient spatter condition and velocity vector distribution obtained the power loss of the gear pair with the change of the rotational speed during the splash lubrication process.Then the comparison between the test results of the gear pair and the loss of the bench and the simulation results were carried out to verify the effectiveness of the MPS-based simulation model of gear pair churning loss.3.Design and build a multi-functional gear churning loss test device,and based on bench test conditions and test methods,different speeds,oil immersion depth,lubricating oil(different viscosity and density),tooth width,helix angle Experimental study on power loss of gear pair coke under the influence of parameters.The experimental research shows that with the increase of the input shaft speed,the churning loss of the gear pair increases continuously,and the higher the rotation speed,the more obvious the increase of the churning loss.The higher the oil immersion depth of the gear,the higher the viscosity and density of the lubricating oil,the larger the gear width and the helix angle,the greater the gear churning loss.Through comparative studies,at the same input speed,the viscosity and density of the lubricating oil have the greatest influence on the churning loss of the gear pair,followed by the gear helix angle,followed by the gear width and gear immersion depth.4.Based on the built-in MPS fluid-solid coupling simulation analysis model,the oil splashes in the gearbox under different tooth widths,different helix angles,different oil immersion depths,different lubricant viscosity and density at different temperatures were analyzed.The velocity vector distribution was studied.The variation law of the churning loss of the gear pair with the rotation speed under different influence parameters was studied.The influence law of each influence parameter on the power loss of the gear pair was analyzed.The research shows that the churning loss of the gear pair is very high under high speed conditions.The influence of the temperature,viscosity and density of the lubricating oil on the churning power loss of the gear pair is also significant.The influence of the gear helix angle on the power churning loss of the gear pair is mainly reflected in the gear pitch line speed;the oil immersion depth and tooth width of the gear have less influence on the churning power loss of the gear pair.It provides a reference for the study of the churning loss of the transmission in practical engineering applications.