chassissuspension071113

IIISuspensionDesignandIVPowertrainIntegrationShockabsorbersShockabsorbersBalljointsBalljointsTiresTiresSpringsSpringsSpringsSpringsBushingsBushingsBushingsBushingsSteering-Column-IntermediateshaftSteering-Column-IntermediateshaftShockabsorbersShockabsorbersSteeringgearSteeringgearStabilizerbarStabilizerbarBrakerotorsBrakerotorsMastercylinderMastercylinderVacuumboosterVacuumboosterABS/TCS/VSESControlmoduleABS/TCS/VSESControlmoduleBrakecalipersBrakecalipersBrakepedalsBrakepedalsShockmountsShockmountsBrakerotorsBrakerotorsFrontsuspensionFrontsuspensionRearsuspensionRearsuspensionPowertrainmountsPowertrainmountsChassisSystems&ComponentsWhatisaSuspensionSystem?Suspensionsystemsperformsixbasicfunctions:1.Maintaincorrectvehiclerideheight2.Manageloadstransmittedtothebodystructure3.Maintaincorrectwheelalignment4.Supportvehicleweight5.Keepthetiresincontactwiththeroad6.Controlthevehicle’sdirectionoftravelAllsuspensionsprovideadifferentbalanceofattributes:–Powertraincompatibility–Drivecompatibility;ie:FWD,RWD,AWD–Vehicledynamicscharacteristics–Packagespace–Mass–Cost–Easeofassembly–Tiresizecapability–Etc.IIISuspensionDesignFrontofVehicleUpperBallJointLowerBallJointKingpinAxisCasterAngleSuspensions-toControlTire/UnsprungMassPositionsToe(Rz)Camber(Rx)Caster(Ry)JounceandRebound(Z)Lateral(Y)Fore-Aft(X)SideViewToeInVehicleCenterlineFrontViewTopViewVehicleCenterlineCamberAngle(+)ToeAngle,Camber,andCasterchangewith:•Wheelposition•Bushingdeflection•Body/ChassisstructuredeflectionsEffectofToeonTireDragForce0%2%4%6%8%10%12%14%16%18%20%00.050.10.150.20.250.30.350.40.450.5Toe-in(degrees)%ChangeinTireDragForce0.1500.2000.250CorneringCoefficientCASTER:NoEffectCAMBER:MinorEffectTOE:MostSignificantEffect-DuetoLateralForceComponentinDirectionofTravelFyFxvαPlantTolerance:±0.1°SuspensionLayoutProcedureC5FrontViewLinesKingpinLayoutRollCenter/ControlArmStrutandSpringControlArmAttachmentsSideView(SwingArm)SteeringLinkageTieRodKeySDFsonDfDrFrontViewSideViewPlanView3DFrontViewLines•GroundLine•SpindleLine•TiresizeandLoadedRadius•TrackWidth•Camber•Body/WheelOffsetandGap•Engine/Powertrain•OtherPackagingConstraintsVehicleCLSpindleCLT/2TireLoadedRadiusγ(+)HoodLineGroundLineLoadvsDeflectionCompresstoRim0204060801001200500010000150002000025000300003500040000AppliedLoad[N]TireDeflection[mm]180kPa240kPaCamberBody/WheelOffsetandGapKingpinLayout•FrontViewTrackwidthWheeloffsetandgapKingpinInclinationScrubRadiusUpperStrutMountSpindleLengthHoodLineGroundLineCLScrubRadius(-)KingpinInclinationSpindleLengthUpperStrutMountFrontViewSideViewCasterTrailCasterOffsetCasterAngle•SideViewCasterAngleCasterTrailKingpinHoodLineGroundLineCKingpinInclinationSpindleLengthUpperStrutMountMacPhersonStrutSuspension•Kingpin,AnImaginarySteeringAxis(SA)•KingpinInclination-Inclinetohaveaminimumornegative(outboard)scrubradius-OuterCVjoint(FWD)tointersectwithKingpintoavoidtorquesteer-Canitbeoutboard(outsideofthewheelcenterline)?CLScrubRadius(-)KingpinInclinationSpindleLengthCLScrubRadius(-)KingpinInclinationSpindleLengthFrontViewMacphersonStrutSLA(DoubleWishbone)SLAScrubRadius-Outboard(negative)scrubradiusreducesFWDtorquesteer(duetouneventiretractionforces)-Balancethesplitµbraking(ParticularlyABS)PivotCenterFxlFxrFxlFxrYawMomentSteeringMomentTopViewDecelerationVehicleVelocityPivotCenterFxlFxrFxlFxrSteeringMomentAccelerationYawMomentTopView•CasterAngle-Oncedisturbed,Castertrail(moment)forcethetirereturntothestraightposition.-Asthewheelsareturned,bothkingpininclinationandcasteranglesjackupthefrontofthecar.Gravitywilllowerthecarandforcethewheelsreturntothestraightposition.-Casterprovidessteeringfeedback•KingpinOffset(SpindleLength)-MinimumKingpinoffsettoreduceshakeduetothetire&wheelimbalance.KingpinKingpinOffsetCentrifugalforceduetoImbalanceCasterTrail(Moment)CasterAnglePivotCenterTopViewSideViewHighRollCenter-Minimumrollmomentduringcornering-Wheelfight/kicklateralshake.Largelateralforcewhentirehitsaroadbump(criticaltofrontwheels)-Excessivetreaddeviationandlateralmovement(equivalentslipangle,force)LowRollCenter-Minimumlateralinterferencewhenhitabump-LargerollmomentInclinedRollAxisAtfront,usestabilizerbartocompensatetherollHighRollCenterLowRollCenter(atgroundlevel)RollCentersRollCenter/ControlArmInstantCenterFrontViewSwingArmRollCenterHeight(RCH)LowerBallJoint(LBJ)LCABushingLongLCARollCenterCLFrontViewCLFrontViewLBJInstantCenterKingpinLCABushingStrutMountRollCenterHeightRollCenter/ControlArmMoreRollCentersShortLongArmHotchkiss/SoldAxleStrutandSpringStrutLengthJounce/ReboundJounceBumperBendingatStrutCounteredbySpringFrictionatStruct(BendingandSideForce)SpringLinkageRatioandDamperLinkageRatioEfficiencyandLoadPackagingLinearNonlinearSpringandRideTravelCoilSpringJounceBumperDamper(ShockAbsorber)Susp.Deflectionvs.LoadMaxEffGVWDesignCurbRebound-150-100-5005010015002004006008001000Load(Kg)SuspDeflection(mm)SpringRequirements:1.Load2.Travel(atvariousloads)3.RideFrequencyCurb:Thisgroundlinecondition(alsoreferredtoasMin.Curb)representsthemostcommonlyusedgroundlinereferencedbyDesignStaffwhenst