Research And Optimization For Bearing Resistance To The Transmission System Of FF Automobile

As the global increasingly energy shortage and people’s increasing attention to environmental issues,the national emission requirements are increasingly high,energy conservation and emission reduction,reducing fuel consumption,and improving fuel economy have become the primary task of the major automobile companies.The transmission system is the most important part of the automobile power assembly,which has a decisive influence on the vehicle fuel consumption.In order to reduce the NEDC fuel consumption of a FF MPV,its transmission system has been studied to reduce the drag resistance and improve the fuel economy of the MPV.The main contents and conclusions are as follows:(1)A economical and practical test method of exploring the key components which influence drag resistance of FF automobiles are developed.The vehicle chassis dynamometer is used to test the steady-state resistance of the vehicle at different speeds,and the drag resistance is decomposed by dismantling the drive shaft and the brake plate to obtain the resistance curve of the object and comparative vehicles.And then key components of object FF MPV’s transmission system have been found out by comparasion and analysis.(2)The formula of the friction torque of the bearing,which include friction between rolling element and raceway,friction between rolling element and cage,lubrication,seal,and other factors,has been established through analyzing influencing factors of the friction torque of the bearing in detail,which lays the foundation of analazing wheel hub bearing and gearbox bearings of the obeject vehicle.(3)The theoretical analysis for friction torque of the seals,negative clearance,grease and precision have been done through the the characteristics of the wheel hub bearing unit of FF MPV.Based on the theoretical analysis,the control variable method is used to test the influence of the seals,the negative clearance and the grease on the friction torque of the wheel hub bearing unit through the wheel hub bearing friction torque test bench,and the precision parameters of the wheel hub bearing were tested comparibly.(4)The theoretical analysis to gearbox efficiency of the bearing ring,roller form,clearance and bearing accuracy have been done through the the characteristics of the gearbox bearings of FF MPV.Based on the theoretical analysis,the control variable method is used to test the change of the gearbox efficiency under the influence factors through a specific workbench.(5)In order to reduce the friction torque of the wheel hub bearing unit and improve the efficiency of the gearbox,the wheel hub bearing unit and gearbox bearings have been optimized and sample pieces have been manufatureed.Fuel consumption tests of NEDC have been done and results shows the combined NEDC fuel consumption of the FF MPV has been reduced by about 0.17L/100 Km.Through the research of this thesis,a whole set of procedures to reduce the drag resistance of FF MPV has been set up,which provides the direction for other FF automobile to reduce the resistance of transmission system.At the same time,the theoretical analysis and experimental verification of the wheel hub bearing and the gearbox bearings have been done,which can provide reference for the follow-up study.