IntroductionAccordingtoNHTSAseatbeltssave13,000livesinUSeachyear7,000UScaraccidentfatalitiescouldhavebeenavoidedifvictimshadbeenwearingbeltsSeatbeltsreducetheriskofdeathforafrontseatcaroccupantbyabout50percentIntroductionAccordingtoNHTSA1HowSeatbeltsWork安全帶工作原理課件2SeatbeltsSeatbelt–spreadsthecrashforcesacrossstrongerpartsofthebodytominimizeinjury.ConsistsoflapbeltandashoulderbeltBeltsextendacrossthepelvis,ribcageandshoulder.Forceisnotconcentratedinasmallarea,soinjuryisreduced.SeatbeltsSeatbelt–spreadsth3CrashworthinessCrumplezones–frontandrearofthecarthatcollapserelativelyeasilyCarseatbeltshavetheabilitytoextendandretractYoucanleanforwardeasily,beltstaysfairlytautInacollision,belttightensupandholdsyouinplaceCrashworthinessCrumplezones–4SeatBeltRetractorsRetractormechanismAspiraledspringrotatesthespooltokeeptheseatbeltwebbingtautSeatBeltRetractorsRetractor5Retractorhasalockingmechanism

Twotypesoflockingmechanisms:Systemstriggeredbythecar’smovementSystemstriggeredbythebelt’smovementRetractorhasalockingmechan6WeightedpendulumtriggeredbycarmovementWhenthecarcomestoasuddenstoptheinertiacausesthependulumtoswingforward.Thepawlontheotherendofthependulumcatchesthetoothratchetgearattachedtothespool.Thegearandspoolcannolongerrotatecounterclockwise.Weightedpendulumtriggeredby71)1)8CentrifugalclutchtriggeredbybeltmovementCentrifugalclutch.Whenthespoolrotatesquickly,centrifugalforcedrivestheweightedendofapivotingleveroutward.Theleverpushesacamconnectedtoapawl.Thepawlmovesintothespinningratchetgearstoppingthebelt.Centrifugalclutchtriggeredb92)2)10PretensionerTightensupslackinthebeltwebbingintheeventofacrashPullsinonthebeltSomepretensionerspulltheentireretractormechanismbackwardandsomerotatethespoolitselfTheyarethesamecentralcontrolprocessorthatactivatesthecar’sairbagsPretensionerTightensupslack11PretensionersProcessormonitorsmechanicalorelectronicmotionsensorsthatrespondtosuddendecelerationofimpactPretensionersbuiltaroundelectricmotorsorsolenoidsPopulardesignstoday-pyrotechnicsPretensionersProcessormonitor12Whenthegasisignited,thepressurepushesthepistonuptorotatetheretractorWhenthegasisignited,thep13PretensionersCentralelement–combustiblegasWhencollisiondetected,itimmediatelyapplieselectricalcurrentacrosselectrodesSparkfromelectrodesignitestheignitermaterial,whichcombuststoignitethegasPressurepushespiston,drivingitupwardRetractormechanism–speedingrackrotatesspoolforcefully,windingupanyslackbeltwebbingPretensionersCentralelement–14LoadLimitersMinimizebelt-inflictedinjuryEarlierloadlimitershadstitchingalingthebeltthatbroketolimittheloadasthebelttightened.AdvancedloadlimitersrelyontorsionbarWhengreatdealofforceisappliedtothewebbing,torsionbartwistsslightlyAllowswebbingtoextendalittlebitfartherLoadLimitersMinimizebelt-inf15From:

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http://auto.howstuffwork16IntroductionAccordingtoNHTSAseatbeltssave13,000livesinUSeachyear7,000UScaraccidentfatalitiescouldhavebeenavoidedifvictimshadbeenwearingbeltsSeatbeltsreducetheriskofdeathforafrontseatcaroccupantbyabout50percentIntroductionAccordingtoNHTSA17HowSeatbeltsWork安全帶工作原理課件18SeatbeltsSeatbelt–spreadsthecrashforcesacrossstrongerpartsofthebodytominimizeinjury.ConsistsoflapbeltandashoulderbeltBeltsextendacrossthepelvis,ribcageandshoulder.Forceisnotconcentratedinasmallarea,soinjuryisreduced.SeatbeltsSeatbelt–spreadsth19CrashworthinessCrumplezones–frontandrearofthecarthatcollapserelativelyeasilyCarseatbeltshavetheabilitytoextendandretractYoucanleanforwardeasily,beltstaysfairlytautInacollision,belttightensupandholdsyouinplaceCrashworthinessCrumplezones–20SeatBeltRetractorsRetractormechanismAspiraledspringrotatesthespooltokeeptheseatbeltwebbingtautSeatBeltRetractorsRetractor21Retractorhasalockingmechanism

Twotypesoflockingmechanisms:Systemstriggeredbythecar’smovementSystemstriggeredbythebelt’smovementRetractorhasalockingmechan22WeightedpendulumtriggeredbycarmovementWhenthecarcomestoasuddenstoptheinertiacausesthependulumtoswingforward.Thepawlontheotherendofthependulumcatchesthetoothratchetgearattachedtothespool.Thegearandspoolcannolongerrotatecounterclockwise.Weightedpendulumtriggeredby231)1)24CentrifugalclutchtriggeredbybeltmovementCentrifugalclutch.Whenthespoolrotatesquickly,centrifugalforcedrivestheweightedendofapivotingleveroutward.Theleverpushesacamconnectedtoapawl.Thepawlmovesintothespinningratchetgearstoppingthebelt.Centrifugalclutchtriggeredb252)2)26PretensionerTightensupslackinthebeltwebbingintheeventofacrashPullsinonthebeltSomepretensionerspulltheentireretractormechanismbackwardandsomerotatethespoolitselfTheyarethesamecentralcontrolprocessorthatactivatesthecar’sairbagsPretensionerTightensupslack27PretensionersProcessormonitorsmechanicalorelectronicmotionsensorsthatrespondtosuddendecelerationofimpactPretensionersbuiltaroundelectricmotorsorsolenoidsPopulardesignstoday-pyrotechnicsPretensionersProcessormonitor28Whenthegasisignited,thepressurepushesthepistonuptorotatetheretractorWhenthegasisignited,thep29PretensionersCentralelement–combustiblegasWhencollisiondetected,itimmediatelyapplieselectricalcurrentacrosselectrodesSparkfromelectrodesignitestheig