Latest Technical Trends regarding Hub Unit Bearings

1 8 Koyo Engineering Journal English Edition (2005)and the 3rd generation type has already achieved predominantuse. regarding the driving wheel on the other hand, the 3rdgeneration type's advantages of compactness and lightweightare less obvious due to dimensional limitations at theconnection between the driving axle and the hub unit is why the evolution to the 3rd generation type has notbeen as rapid as that for the driven IntroductionIn response to recently increasing needs for compact,lightweight and reliable components as well as the trendtoward component modularization.

2 Automobile wheel bearingshave been combined with other wheel components such asknuckles and hub shafts to form integrated wheel componentsreferred to as hub unit Bearings , along with recent requirements for automobilesuspension components to be more environmentally friendlyand safer, automotive wheel Bearings are being required toexhibit technological improvements including betterperformance and higher author previously presented a report1)on technicaltrends regarding hub unit Bearings focusing on their designfeatures. This report will introduce some recent producttechnology Technical Challenges related to Hub UnitBearingsHub unit Bearings are classified as 1st, 2nd and 3rdgeneration in accordance with their mode of integration withother components.

3 Each of these types has been 1shows a typical 3rd generation hub unit bearingwhich lately been predominantly used for the driven wheels ofpassenger cars. The 3rd generation hub unit bearing iscomprised of a 1st generation ball bearing unit, a flangeintegrated with the outer ring for mounting on the knuckle,and a hub shaft integrated with the outer side inner unit Bearings installed in passenger cars are mainly theball bearing type. However, the pattern of evolution from 1stgeneration to 3rd generation for the driven wheel has not beenthe same as that for the driving 1shows the advantages and disadvantages of 1stgeneration and 3rd generation hub unit Bearings from thestandpoint of the the driven wheel, the advantages of 3rdgeneration type compared to 1st generation type are evident,Facing the increasingly pressing needs for compact, lightweight and high-performing automotive parts and the trend towardmodularization.

4 Automotive wheel Bearings have evolved into hub unit Bearings . More recently, 3rd generation hub unitbearings have been in high-volume this paper, various problems concerning 3rd generation hub unit Bearings and the technology used to resolve suchproblems are Words: hub unit bearing, automotive wheel bearing, moment rigidity, FEM analysis, high-precision hub flangeLatest Technical Trends regarding Hub Unit BearingsT. NUMATATECHNICAL TRENDHub shaftOuter ringABS sensorShaft end clinchingFig. 1 3rd generation hub unit bearingTable 1 Advantages and disadvantages of 3rd generation hubunit bearingItemsDriven wheelDriving wheel1st #%%Lightweightness # %PerformanceLife%#%#Stiffness # #Running torque%#%#Flange runout%#%#Sensor acceptance##%%Compactness # %Overall evaluation # %Advantage.

5 #> %> Latest Technical Trends regarding Hub Unit Bearings 9 Koyo Engineering Journal English Edition (2005)However, in view of the advantages of integrated units inthe installation process, it is expected that 3rd generation hubunit Bearings also will be adopted more broadly for the drivingwheels. Consequently, future technological development willmost likely focus on 3rd generation hub unit 2is a summary of various needs related to 3rdgeneration hub unit Bearings and examples of correspondingtechnology being this paper, these issues and the technology employed toresolve them are Progress of Analysis and SimulationTechnology (for Shortening DevelopmentPeriod)Until this point, development evaluation of hub unitbearings has often relied on experiments.

6 This approach,however, has caused delay in the development period becauseany problems revealed during prototype evaluation havenecessitated repeating the development processes from designto prototype manufacture to evaluation , recent advances in computers' processingcapability and the progress of numerical analysis technologyhave made it possible to conduct desk investigations that usedto be order to accelerate development as well as to reduceprototype cost, Koyo has promoted "front-loading" of thedevelopment process by use of CAE so that designers canassess their designs against final objectives themselves byusing regarding hub unit bearing analysis, Koyo usesnoise and strength/stiffness analyses to reduce the number ofexperiments as well as stress mechanism analysis during andafter processes such as shaft end clinching to obtain representative examples, efforts regarding strength/stiffness analysis and shaft end clinching analysis areintroduced below:3.

7 1 Strength/Stiffness AnalysisAlthough strength/deformation analysis has long been usedas a basic type of FEM analysis, recently its reliability hasbeen dramatically improved because of efforts to conformanalysis results with experimental has worked on refinement of FEM analysis for thestrength/stiffness of hub unit Bearings to improve consistencywith experimental results and has established technology tokeep analysis error within 10%2).Figure 3shows a comparison of FEM analysis andexperimental results regarding hub unit stress. This shows thatanalysis results are highly consistent with experimental resultsunder different load , Fig.

8 4shows a comparison between FEM analysis ofmoment stiffness and experimental results. In this analysis, thestiffness of the knuckle (including outer ring) and hub shaftwas analyzed by FEM, the bearing stiffness was calculated bya program developed in-house, and the moment stiffness ofthe entire unit was obtained by adding the values computed foreach component. Here again, the analysis results had highconsistency with the experimental results. Needs from vehicleRequirements of bearingsTechnology incorporatedImproved function and performance Improved maneuverability Elimination of brake judder Elimination of abnormal noiseSafety and environmental friendliness Better fuel economy Light weight Advanced vehicle controlLateral load accommodationIntegrated designMinimized brake rotor runoutReduced stick slip noiseReduced running torqueLightweight with stiffnessIntegration of high function sensorBearing analysis simulating high lateral load3rd generation (Driving wheel)

9 Assembled rotor processingMinimized flange runoutNoise source analysis systemLow torque sealLightweight analysis systemHigh resolution, forward/backward detecting sensor (resolver) Cost reductionReduced cost of manufacturePrecision forgingMANU-facturing technique Accelerated developmentFront loading High stiffnessAdvanced analysis/simulation technologyFig. 2 Current vehicle needs and solutions promoted in hub unit bearingsPosition APosition BPosition APosition BPosition APosition BFEMA ctual measurementFEMA ctual measurementMaximum primary stressMaximum primary stressLoad condition qLoad condition wLoadLoadFig.

10 3 Comparison between actual measurement results and analysis regarding stress Latest Technical Trends regarding Hub Unit Bearings 10 Koyo Engineering Journal English Edition (2005)Some examples of contributions made by 3rd generationhub unit Bearings to the improvement of vehicle function andperformance are introduced 1 Measures for High Stiffness and High LateralLoadRecently, progress in vehicle movement control technologyhas been remarkable. Various types of system controltechnology such as anti-lock brake systems (ABS) areprovided as standard equipment to improve the safety andcomfort of the other hand, such advances in vehicle control havetended to increase the load on components around thesuspension.