Oil-mixing Lubrication Analysis And Transmission Efficiency Research Of Gearbox Based On CFD

Gear box is an important part of automobile transmission system,which has the function of power transmission and changing transmission ratio,and can ensure the smooth operation of transmission system under different working conditions.The transmission efficiency and lubrication state of gearbox are the technical indexes affecting the performance of the whole vehicle,which have an important impact on the power,economy and environmental performance.The gearboxes carried by electric vehicles are mostly single-stage or two-stage transmission,and the optimization space of gear parameters and box structure is small.In order to improve transmission efficiency and power performance,the requirements for energy saving of lubricating oil and reliability of gear lubrication are increasingly stringent.Therefore,it is necessary to conduct in-depth research combining the characteristics of gear and lubricating oil.In this paper,the mathematical model of gear box transmission efficiency,the simulation model of oil-stirring lubricant and the dynamic model are constructed,and the influence factors and rules of transmission efficiency and gear lubrication state are determined by the transmission efficiency bench test.The oil-stirring lubrication scheme considering both transmission efficiency and lubrication state of gear box is put forward.It provides a reference for the design and optimization of complex transmission lubrication system from the selection of lubricant varieties and the setting of oil quantity.The main contents of this paper are as follows:(1)To analyze the energy loss mechanism of gear box oil mixing lubrication and the factors affecting transmission efficiency.The development status of lubrication and efficiency optimization of gearbox at home and abroad was studied.The source,transmission way and influencing factors of power loss of gearbox were analyzed.Mathematical calculation model of transmission efficiency of gearbox was established based on MATLAB,and the law of five different types of power loss,such as power loss of stirring oil,varying with rotational speed,was analyzed.(2)Gear box fluid modeling and simulation analysis.The lubrication model of gas-liquid two-phase flow was established and the flow field was analyzed.The transient spatial distribution law and velocity vector law of lubricant sputtering in gear box were obtained.The influence of gear box working condition and initial lubricant setting on gear box transmission efficiency was studied,and the parameter range of improving gear box transmission efficiency was analyzed.(3)Lubrication analysis of gearbox.A dynamic model was constructed to analyze the relationship between the oil film thickness and the lubricant parameters.The film thickness ratio of the gear meshing area was calculated during the parameter change process,and the corresponding lubrication effect was analyzed.The parameters range of the gear under good lubrication condition was obtained.The reliability of the gear box was studied by combining theoretical calculation with finite element analysis.(4)Gear box transmission efficiency test.Based on the orthogonal experiment and correlation analysis,the experimental data are analyzed statistically.The weight and law of the influence of rotational speed,oil immersion depth,torque and lubricant viscosity on the transmission efficiency of gearbox are studied.The reliability of the simulation analysis is verified by comparing the experimental data with the theoretical model.(5)Verify the optimization scheme.Based on the transmission efficiency test,the transmission efficiency optimization scheme is determined.The parameters of the scheme provide a reference for the reasonable selection of lubricating oil varieties and oil quantity used in complex transmission,thus improving the transmission efficiency of gearbox.