| Gear reducer is an important part of transmission system.During operation,a large amount of heat is generated due to friction of gears.At the same time,high speed rotation of gears can easily lead to insufficient lubrication and cooling of meshing tooth surface,which will eventually cause dangerous situations such as high temperature of transmission system,deformation failure or jamming of gear teeth,etc.Therefore,it is important to analyze the flow and distribution of the lubrication oil and the temperature of the gears in the gearbox during operation,which is essential for the design and optimization of high speed gearboxes.In this paper,the combination of theory and simulation is used to study the flow and temperature field of a jet-lubricated planetary reducer.The main contents and conclusions are as follows:(1)The analytical method is used to calculate the meshing loss power of the gear,and the heat generation of gear meshing simulation is compared with the theoretical results to verify the accuracy of the theoretical calculation.The windage loss during gear rotation is calculated by simulation,and compared with the previous theoretical formulas and experimental results,the feasibility of the simulation of windage loss is proved.The heat flow boundary is provided for the temperature simulation in the following chapters.(2)An injection lubrication analysis model for a pair of helical gears is established,and the model's flow and temperature filed are simulated.The FLUENT software is redeveloped;the distributed heat source is applied to the meshing tooth surface by UDF program.The oil volume fraction,heat transfer coefficient and temperature distribution of gear tooth surface are obtained,and the rationality of the results is analyzed,which provides a technical route for the study of influence factors of flow and temperature filed in the following paper.(3)The effects of gear speed,injection distance and injection flow on the flow and temperature distribution are studied.It is found that the overall heat generation power and tooth surface temperature increase with the increase of the rotational speed,but windage loss is rising faster than the meshing loss.The increase of injection distance will make it more difficult for lubricating oil to enter the meshing area.Oil volume fraction and heat transfer coefficient of the tooth surface in the meshing area will decrease,the meshing power loss and temperature of gear increase.In a certain range,the increase of injection flow will obviously enhance the oil volume fraction and reduce the meshing loss and the temperature on the tooth surface.But when the injection flow increase to a certain extent,oil volume fraction will reach saturation,and the temperature of the tooth surface will no longer decrease with the increase of injection flow.(4)The flow and temperature filed of a planetary reducer are simulated and analyzed.It is found that oil volume fraction in the meshing area of each pair of gears is generally low,causing excessive heat generation during sun gear engagement,poor heat dissipation and high temperature of tooth surface.According to the poor lubrication and heat dissipation of the reducer,the injection flow and injection distance of the nozzles are optimized and improved,and the improved model is analyzed again to verify the effectiveness of the improved scheme. |
PDF Full Text Request