Analysis And Calculation On Transmission Efficiency Of Transmission For Light-Duty Automobile

With the energy crisis becoming increasingly prominent,reducing fuel consumption and improving the fuel economy of the vehicles have become huge challenge which the major automobile factories have to face in recent years.The transmission is one of the main parts of the powertrain system,and its power loss has a great influence on the fuel economy of the vehicle.The transmission power loss prediction model is established to predict the transmission efficiency of the gearbox and understand the law of impact that the transmission structure and operating factors influence on the transmission.This is an important and indispensable part to design the transmission reasonable and improve the transmission efficiency.The main research contents and conclusions are as follows:(1)Calculation of the meshing efficiency of helical gear and analysis of the influencing factors1)Calculation method of helical gear load distributionAccording to the involute equation,involute spiral surface equation and gear meshing characteristics,the spatial position relation of the meshing points on the contact line is analyzed,and the contact line equation of the helical gear is deduced and further the time-varying contact line is solved.Considering the elastic deformation of the support shaft,deformation of the tooth bending,and the local contact deformation of the gear,the problem of load distribution is treated as linear programming in which the maximum rigid body displacement is seen as the objective function and the contact conditions when the gears mesh is the constraint condition.The load distribution of helical gears is programmed by interior point method,and the results by this method was compared the results with those of static contact pressure distribution of the helical gear obtained by three-dimensional finite element analysis method.The results show that the load distribution by this two methods is basically the same in the region where no the stress concentration occurs,which shows that the theoretical calculation method of the load distribution is correct.2)Meshing efficiency calculation of helical gear and analysis of influencing factorsBased on the analysis of the principle of sliding friction loss and rolling friction loss,the instantaneous and average meshing efficiency of the helical gears werecalculated and compared with experimental results in literature.The results indicate that the meshing efficiency calculated by theoretical method is basically agreeable with that of the experimental test.Finally,the influences of the gear structure and lubricating oil characteristic parameters on gear meshing efficiency were analyzed,and the corresponding influence rule has been summarized.(2)Analysis on the mechanism and influencing factors of the gear padding lossBased on the analysis of the mechanism of the padding loss,the padding power loss was calculated,and the influences of gear structure parameters and lubricating oil characteristic parameters on the padding loss were analyzed.The padding loss increases with the increase of the tooth width,the rotational speed,the depth of the lubricating oil,the volume of the lubricating oil and the viscosity of the lubricating oil,among which the rotational speed has the greatest influence on the padding loss.(3)Analysis on the mechanism and influencing factors of bearing friction lossBased on the analysis of the mechanism of the bearing friction power loss,the bearing friction power loss was calculated,and the influences of the viscosity of the lubricating oil,the bearing speed,the equivalent dynamic load and the average diameter of the bearing on the friction loss of the bearing were analyzed.The four influencing factors are positively correlated with the bearing friction loss.The bearing speed has the greatest influence on the bearing friction loss.(4)Application of calculation method on the transmission efficiencyTaking the newly developed 6-speed manual transmission of some factory as the research object,the transmission efficiency of the gearbox under different working conditions was calculated and compared with the experimental test results.The results show that it is feasible to predict the transmission efficiency of the transmission with the method of the theory combined with the empirical estimation.