antilock abs1 ppt
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ANTILOCKBRAKINGSYSTEM
By
Y.Krishnakumar 08245A0303
T.Prashanth Babu 08245A0309
C.Karthik kumar 08245A0311
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ABSTRACT
Intodaysworld,brakingisthemostimportantsysteminanAutomobile.
Brakesareenergyconversiondevices,whichconvertkineticenergyofthevehicleintothermalenergy.
InAntilockBrakingSystem,wecanpreventthelockingofthewheelandhenceskidding,usinganElectroMechanicalControlSystem
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INTRODUCTION
Inrecentyears,withadvancementindesign&technology,Discbrakesarefastreplacingdrumbrakes.
ABSwasfirstdevelopedforAircraftsbrakingsystembutsoonstartedreplacingtheconventionalbrakingsystemintrucksandcars.
RecentimprovementsinABSallowstopreventwheelwhenacceleratedonwetorslipperysurface.
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OPERATIONPRINCIPLE
Limitingthepressuretoanywheelwhichdeceleratestoorapidly isthebasicprincipleemployedinABS.
Aspeedsensorisusedformeasuringthespeedofthewheelandsendsitconstantlytothecomputer.
Dependingontheinitialbrakepressureandthespeedofthewheel,thecomputermodulatesthebrakepressureasfastasfifteentimespersecond.
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STRUCTURE&OPERATIONOFTHEABS
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TERMINOLOGY
ABSActuatorWorkhorseoftheABS. ABSChannel HydrauliclineconnectingABSactuatorandthewheel.
ABSSensorItconsistsagearshapedsensorrotorandsensorelement.
ABSValves Valvesareusedinbrakelineforcontrollingtheeachbrakedependingonitsposition.
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TERMINOLOGY
ABSPumpsItisusedforpumpingthebackuppressurefromthereservoirtothebrakecylinder.
ABSPulseorModulation Thebrakingpressureisfluctuatingfifteentimespersecondforpreventingthelockingofthewheel.
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DIFFERENTTYPESOFABSSYSTEMS
1or2channel2Wheel(RearABS) 2Channel4WheelCriss cross 3Channel4Wheel 4Channel4Wheel4Channel4Wheelisconsideredbetterthantheotherthreesystems.
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ADVANTAGES
Itcanbeusedforreducingthestoppingdistance.
Itenablestosteerwhilethebrakesarefirmlyapplied
Itallowsbrakingfirmlyonsurfaceswithdifferentlevelofgrips.
Itcanreviewandadjustthedriversdriving.
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DISADVANTAGES
DriversmaytakemoreriskswhendrivingwithvehiclesfittedwithABS.
Inexceptionalcircumstances,somedrivershavetheskilltostopthevehicleinashorterdistancethanachievedbyanABSequippedvehicle.
PeoplewhoareinexperiencedinusingABSmayrespondinappropriatelywhentheyactivatethesystem.
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LUCASGIRLINGANTILOCKBRAKINGSYSTEM
HydraulicSystem Discbrakeshydraulicstotriggerbraking. Whenthedriverpressesonthebrakepedal,pistonismovedinthemastercylinder.
Thisincreasesthepressureinthemastercylinderwhichthenraisesthepressureinthebrakecylinder.
Thismakesthepistontomoveouttocontactthebrakepadsandengagesthebrakesagainsttherotor
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Main Components of Disc Brakes System
-Wheel Shaft-Rotor/Disc-Caliper and its mounting-Brake Cylinders-Pistons-Brake Pads
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WORKING Whenlockingoccurs,thecontrolvalveopensthepumpandreducesthepressureinthecavity.
Thentheactuatorslidesbackfurtherreducingthepressureinthecavitybecauseofvariablecrosssection.
Sincethelockingisnolongerimminentthecontrolvalvereturnsbacktooriginalposition.
Thisopensthevalveconnectingthemastercylindertothebrakingcylinderandnormaloperationofbrakecommences.
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GYROSCOPICCOUPLE
Averticalreactionontheroadsurfacewillbeproducedduetogyroscopiccouple.
Theequationforthegyroscopiccoupleisgivenby
C=Cw CE=(wxp)(4xIwGxIE)
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EXAMPLEPROBLEMTOUNDERSTANDANTILOCKBRAKINGSYSTEM
AVehiclemovesonleveltrackwiththespeedof72km/h.Thebrakesareappliedtofourwheelsandthecoefficientoffrictionis0.5.Findthetimetakenbythevehicletocometorest?
Sol:
ThedecelerationoftheVehicleisgivenby
a=gxfrictionalcoefficient.
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a=gxcoefficient
=9.81x0.5
=4.905m/s2
Thetimetakenbythevehiclebeforecomingtorestisgivenbytheequation,
v=u+(axt)
0=20 (4.905xt)
t=4.077sec.
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Att=3sec,v=5.285m/s.
Assumethatthevehiclewheellocksupafter3seconds,
ThenwithABSoperatedvehiclethebrakeisapplied15timespersecond.
Thevelocitiesateachpointafter3secondsareasfollows.
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v1=5.059m/sv20=0.753m/sv2=4.833m/sv21=0.528m/sv3=4.578m/sv22=0.303m/sv4=4.353m/sv23=0.07m/sv5=4.128m/sv6=3.903m/sv7=3.678m/sv8=3.453m/sv9=3.228m/sv10=3.00m/sv11=2.778m/sv12=2.55m/sv13=2.32m/sv14=2.10m/sv15=1.87m/sv16=1.65m/sv17=1.42m/sv18=1.203m/sv19=0.978m/s
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TotaltimetakenbyABSoperatedvehicle,
t=3+1.518
=4.518sec
Hence,thegyroscopiccoupleforcewillcomedowngraduallyinABSoperatedvehicle.
Thevehiclecomestoreduc restbying thisskiddingeffect.
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CONCLUSION
Becauseofitsroleinpreventingthewheelsfromlockingandbettersteeringcontrolduringbraking,AntilockBrakingSystemshouldbemademandatoryforallvehicles.
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REFERENCES
ThejournalsofSocietyofAutomotiveEngineersIndia(SAE India)
WilliamH.Crouse andDonaldL.Anglin,AutomotiveMechanics,10th Edition,Tata McGraw HillPublishingLimited.
TheoryofMachinesbyR.s.Kurmi
ANTI-LOCK BRAKING SYSTEMABSTRACTINTRODUCTIONOPERATION PRINCIPLESTRUCTURE & OPERATION OF THE ABSTERMINOLOGYTERMINOLOGYDIFFERENT TYPES OF ABS SYSTEMSADVANTAGESDISADVANTAGESLUCAS-GIRLING ANTILOCK BRAKING SYSTEMWORKINGGYROSCOPIC COUPLEEXAMPLE PROBLEM TO UNDERSTAND ANTI LOCK BRAKING SYSTEMCONCLUSIONREFERENCES