howseatbeltswork安全带工作原理

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1、HowSeatbeltsWorkIntroductionAccordingtoNHTSAseatbeltssave13,000livesinUSeachyear7,000UScaraccidentfatalitiescouldhavebeenavoidedifvictimshadbeenwearingbeltsSeatbeltsreducetheriskofdeathforafrontseatcaroccupantbyabout50percentSeatbeltsSeatbelt–spreadsthecrashforcesacro

2、ssstrongerpartsofthebodytominimizeinjury.ConsistsoflapbeltandashoulderbeltBeltsextendacrossthepelvis,ribcageandshoulder.Forceisnotconcentratedinasmallarea,soinjuryisreduced.CrashworthinessCrumplezones–frontandrearofthecarthatcollapserelativelyeasilyCarseatbeltshavethe

3、abilitytoextendandretractYoucanleanforwardeasily,beltstaysfairlytautInacollision,belttightensupandholdsyouinplaceSeatBeltRetractorsRetractormechanismAspiraledspringrotatesthespooltokeeptheseatbeltwebbingtautRetractorhasalockingmechanismTwotypesoflockingmechanisms:Syst

4、emstriggeredbythecar’smovementSystemstriggeredbythebelt’smovementWeightedpendulumtriggeredbycarmovementWhenthecarcomestoasuddenstoptheinertiacausesthependulumtoswingforward.Thepawlontheotherendofthependulumcatchesthetoothratchetgearattachedtothespool.Thegearandspoolca

5、nnolongerrotatecounterclockwise.1)CentrifugalclutchtriggeredbybeltmovementCentrifugalclutch.Whenthespoolrotatesquickly,centrifugalforcedrivestheweightedendofapivotingleveroutward.Theleverpushesacamconnectedtoapawl.Thepawlmovesintothespinningratchetgearstoppingthebelt.

6、2)PretensionerTightensupslackinthebeltwebbingintheeventofacrashPullsinonthebeltSomepretensionerspulltheentireretractormechanismbackwardandsomerotatethespoolitselfTheyarethesamecentralcontrolprocessorthatactivatesthecar’sairbagsPretensionersProcessormonitorsmechanicalo

7、relectronicmotionsensorsthatrespondtosuddendecelerationofimpactPretensionersbuiltaroundelectricmotorsorsolenoidsPopulardesignstoday-pyrotechnicsWhenthegasisignited,thepressurepushesthepistonuptorotatetheretractorPretensionersCentralelement–combustiblegasWhencollisiond

8、etected,itimmediatelyapplieselectricalcurrentacrosselectrodesSparkfromelectrodesignitestheignitermaterial,whichcombuststoign