Research And Optimization Design On The Gear Churning Power Loss Of The Main Reducer

As the key component of the vehicle transmission system,the transmission efficiency of the main reducer will directly affect the fuel economy of the vehicle.During the working process of the main reducer,the factors that produce the power loss mainly include gear meshing loss,bearing friction loss and the churning loss of the rotating components.Generally speaking,the gear meshing loss is the main cause of power loss in a gear transmission system,but when the system is in the running state of low-load and high-speed,the churning loss of the gear may occupy the dominant position.Therefore,there has been a necessary to study the churning of the gear.This thesis studies the churning loss of the passive bevel gears during the operation process.Analyzes the relationship between the churning loss of passive bevel gear and various influencing factors and the composition of churning resistance,and optimizes the relative structure and lubricating oil circuit of the main reducer,thus reducing the churning loss and improving the transmission efficiency.The research process is as follows:Firstly,compared and analyzed the classical calculation model of gear churning loss in the past years,selecting the more accurate model whose deficiencies were analyzed and corrected so that a calculation model considering the effect of temperature was presented.And then verifying the correctness of the modified calculation model through simulation analysis and experimental analysis;Second,a three-dimensional model of automobile rear axle and a fluid simulation model of main reducer's passive bevel gear stirring oil were established.Based on the dynamic grid technique and VOF two-phase flow model in fluent,the velocity field and pressure field of the passive bevel gear stirring oil at different temperature,different rotational speed and different dipping depth were obtained.The relationship between the power loss of the gear churn and the influencing factors were analyzed to verify the correctness of the correction model;Thirdly,the distribution of the flow field of the passive bevel gear of the main reducer was studied,the composition of the fluid resistance in the stirring process was analyzed,and the structure that producing turbulence was optimized to reduce the fluid resistance.The optimized structure verified by the theory and the simulation was checked.The stirring oil circuit of the passive bevel gear was optimized according to the boundary layer theory to reduce the oil loss again.The optimized structure was analyzed by fluid simulation.And compared with the pre-optimized flow field to determine the feasibility of the optimization scheme;Finally,the experiment was designed to verify the correctness of the modified theoretical model and the model of fluid simulation.The optimized sample was manufactured according to the optimization scheme,and the experiment was carried out again.By comparing and analyzing the experimental results before and after optimization,the optimization effect of optimization scheme is determined.It had been found that about 34 percent oil churning losses could be reduced.Then,the fuel consumption test of the rear axle before and after optimization was carried out.The results showed that the fuel consumption of the vehicle is reduced by 0.12 L /100 km,which means the fuel economy of the vehicle is improved.Summaries and forecasts of the full text were presented at the end of the article.