A continuously variable transmissionWord文档格式.docx

A continuously variable transmissionWord文档格式.docx

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neutral"

stanceonamotorcycle（usefulwhenidling,ormanuallyreversingintoaparkingspace）.

Contents

[show] 

∙1Uses

∙2Types

o2.1Variable-diameterpulley（VDP）orReevesdrive

o2.2Toroidalorroller-basedCVT（ExtroidCVT）

o2.3MagneticCVTormCVT

o2.4InfinitelyVariableTransmission（IVT）

o2.5RatchetingCVT

o2.6HydrostaticCVTs

o2.7NaudicIncrementalCVT（iCVT）

▪2.7.1Highfrictionallosses

▪2.7.2Shockanddurability

▪2.7.3Torquetransferabilityandreliability

o2.8ConeCVTs

o2.9RadialrollerCVT

o2.10PlanetaryCVT

∙3History

∙4Seealso

∙5Notes

∙6References

[edit]Uses

AChain-drivenCVT

PrincipleofVariator

ManysmalltractorsforhomeandgardenusehavesimplerubberbeltCVTs.Forexample,theJohnDeereGatorlineofsmallutilityvehiclesuseabeltwithaconicalpulleysystem.Theycandeliveranabundanceofpowerandcanreachspeedsof10–15 

mph（16–24 

km/h）,allwithoutneedforaclutchorshiftinggears.Nearlyallsnowmobiles,oldandnew,andmotorscootersuseCVTs,typicallytherubberbelt/variablepulleyvariety.

SomecombineharvestershaveCVTs.TheCVTallowstheforwardspeedofthecombinetobeadjustedindependentlyoftheenginespeed.Thisallowstheoperatortosloworaccelerateasneededtoaccommodatevariationsinthicknessofthecrop.

CVTshavebeenusedinaircraftelectricalpowergeneratingsystemssincethe1950sandinSportsCarClubofAmerica（SCCA）Formula500racecarssincetheearly1970s.CVTswerebannedfromFormula1in1994duetoconcernsthatthebest-fundedteamswoulddominateiftheymanagedtocreateaviableF1CVT.[2]Morerecently,CVTsystemshavebeendevelopedforgo-kartsandhaveproventoincreaseperformanceandenginelifeexpectancy.TheTomcarrangeofoff-roadvehiclesalsoutilizestheCVTsystem.

Somedrillpressesandmillingmachinescontainapulley-basedCVTwheretheoutputshafthasapairofmanuallyadjustableconicalpulleyhalvesthroughwhichawidedrivebeltfromthemotorloops.Thepulleyonthemotor,however,isusuallyfixedindiameter,ormayhaveaseriesofgiven-diameterstepstoallowaselectionofspeedranges.Ahandwheelonthedrillpress,markedwithascalecorrespondingtothedesiredmachinespeed,ismountedtoareductiongearingsystemfortheoperatortopreciselycontrolthewidthofthegapbetweenthepulleyhalves.Thisgapwidththusadjuststhegearingratiobetweenthemotor'

sfixedpulleyandtheoutputshaft'

svariablepulley,changingspeedofthechuck.Atensionerpulleyisimplementedinthebelttransmissiontotakeuporreleasetheslackinthebeltasthespeedisaltered.Inmostcasesthespeedmustbechangedwiththemotorrunning.

CVTsshouldbedistinguishedfromPowerSharingTransmissions（PSTs）,asusedinnewerhybridcars,suchastheToyotaPrius,HighlanderandCamry,theNissanAltima,andnewer-modelFordEscapeHybridSUVs.CVTtechnologyusesonlyoneinputfromaprimemover,anddeliversvariableoutputspeedsandtorque;

whereasPSTtechnologyusestwoprimemoverinputs,andvariestheratiooftheircontributionstooutputspeedandpower.Thesetransmissionsarefundamentallydifferent.HowevertheMitsubishiLancer,ProtonInspira,HondaInsight,HondaFit,andHondaCR-Zhybrids,theNissanTiida/Versa（onlytheSLmodel）,NissanCube,Juke,Sentra,Altima,Maxima,Rogue,X-Trail,Murano,Micra,HondaCapa,HondaCivicHX,JeepPatriotandCompass,andSubaruImpreza,LegacyandOutbackofferCVT.

[edit]Types

ToyotaSuperCVT-i

[edit]Variable-diameterpulley（VDP）orReevesdrive

InthismostcommonCVTsystem,[3]therearetwoV-beltpulleysthataresplitperpendiculartotheiraxesofrotation,withaV-beltrunningbetweenthem.Thegearratioischangedbymovingthetwo