莲花公司减振器培训教程

LotusEngineeringAnIntroductiontoDampersDampers–Introduction•Twomaintypesofdamperdesign-TwinandMonotubes•ChassisperformancealsoaffectedbythedamperendmountingsDamperTestData•Dampingforceismainlydeterminedby:-–Dampervelocity–Damperacceleration–Damperdisplacement(insomecases)•SimplePV(PeakVelocity)curvethustellsonlypartofthestory:-–Differentvalvespecscanproducesimilarforcegraphs,butfeeltotallydifferentoncarVelocitym/sForce(N)-10001000200030000.50.251.251.00.7501.5DamperTestDataLoopdiagram•IsanalternativetothePVcurve•Usedtostudy‘lag’orpoorpriming•CanalsohighlightcavitationissuesDisplacementForce(N)-1000-25-505025100020003000DamperCharacteristicsVelocitym/sForce(N)-10001000200030000.50.251.251.00.7501.5LinearDigressive‘VelocityDependant’Dampingcharacteristicscanbeseparatedinto3maingroups–Linear–Digressive–VelocityDependantInsomecasesthesearedeterminedbyvalvearchitecture,therefore:-–basiccharacteristicscannotbemodifiedHowever,goodvalvearchitecturecanprovideanyofthesecharacteristicsifrequiredDampers-VehicleBehaviourDampersexertcontrolovermanyaspectsofvehiclebehaviour•Lowvelocityarea-A–Steeringfeel,lowfrequencybodymotions,lowspeedisolation•Midvelocityarea-B–Unsprungmasscontrol,engineshake,impactfeel,bodycontrolduringmoderatemanoeuvres•Highvelocityarea-C–Impactfeel,sprungmassprotection,andbodycontrolduringextrememanoeuvresVelocitym/sForce(N)-10001000200030000.50.251.251.00.7501.5ABCDamping-OtherConsiderations•UnsprungMassAswellastheprimarymotions,thedamperisusedtocontroltheunsprungmass,intermsofshake(secondaryridecomfort)anddynamictyreloads(handlingandstability).Thelowertheunsprungmassthelessthecompromisebetweenoverallridecomfortandhandling.•VelocityRatioSomesuspensionsystemsproduceapoordampervelocityratio.Thisleadstohighdamperforcestocontrolthesprungandunsprungmasses.Thisalsorequiresstrongandstiffattachmentpointsforthedamper.•DampermountingsOnroadvehiclesthesenearlyalwayscompriseofarubberbush(whichcanbeverysimpleorcomplexindesign).Withoutthecorrectrelevantstiffnessanddampingcharacteristicsofthismount,itwouldbedifficulttogenerateandcontrolhighdamperforces.TwinTubeDampers–‘Basic’OilFlowTwintubesPistonmovingincompressionIntakeplatedeflected,allowsoiltoflowPistonmovinginreboundIntakeplate‘blocks’oilflowOilnowflowsthroughreboundvalveIntakevalves-ControlthedirectionofoilflowIntakeplateOilflowsbetweenthepressuretubevolumeandtheoutercasevolume–throughthebasevalveand–throughthepistonTwinTubeDampers–Piston‘Control’OilFlowPistonReboundControl–Oilflowthroughthepistoniscontrolled.Thisisthemajormechanismforrebounddamping.–OilalsoflowsthroughintakevalveofbasevalveVelocitym/sForce(N)0.5101.5ABCOilflowsthroughlowspeed‘leak’-requireslowforceALargerflowspartlydeflectdiskstogaingreateroilflow-requiresincreasedforceBGreatestflowsfullydeflectdisksandarerestrictedbytotalorificeareaCTwinTubeDampers–BaseValve‘Control’OilFlowBaseValveCompressionControl–Oilflowthroughbasevalvecontrolled.Thisisthemajormechanismofcompressiondamping.–OilalsoflowsthroughintakevalveofpistonOilflowsthroughlowspeed‘leak’AVelocitym/sForce(N)0.5101.5ABCLargerflowspartlydeflectdisksBGreatestflowsfullydeflectdisksandarerestrictedbytotalorificeareaCTwinTubeDampers–Pressurisation(‘Gassing’)Gassing-Reducestheformationofairbubblesinthedamperoil•Thisimprovesdamperperformance(moreconsistentdampingacrossarangeofoperatingconditions)•Reducesdamper‘swish’noise•Nitrogenisused(inert)•Typicalpressurerange=2-8barMonotubeDampers–‘Basic’OilFlow•Thereboundandcompressionforcesarebothdeterminedbythevalvesettingsonthepiston•Monotubeshavegoodfaderesistanceandcanbemountedatanyangle•TypicallyusedinhighperformancevehiclesOilflowsbetweentheupperandlowerchamber–throughthepistononly–upperandlowerchambersremainfullofoilatalltimes–volumechangesarecompensatedbythefloatingpistonGasFloatingPistonUpperChamberLowerChamberMonotubeDampers–Rebound‘Control’OilFlowMonotubeDampers–Compression‘Control’OilFlowDampers–ShimStacksThisarrangementcanbesupplemented/replacedintwin-tubeswithspringarrangements•Variationsinmid/highvelocityforcescanbeobtainedbydifferingmethods.•Mostcommonisa‘tune-able’shimstack•Oilflowdeflectsthediscsawayfromthepistonorbasevalve‘land’•Shimsareselectedonthebasisofthickness&diameterSimple‘Pyramidstack’shownCombinationsinclude:–Discdiameter–Discthickness-stiffness–Numberofdisc’sValveArchitecture–TwinTubePistonValveArchitecture–TwinTubePistonValveArchitecture–TwinTubeBaseValveValveArchitecture–TwinTubeBaseValveValveArchitecture-MonotubeThereboundandcompressionbypassmaybeseparatedusinganon-returnshim