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MECHANICAL ENGINEERING DEPARTMENT
KRISHNA INSTITUTE OF ENGINEERING AND TECHNOLOGY
GHAZIABAD
SEMINAR REPORT
ON:-ANTILOCK BRAKING SYSTEM
B. Tech (Mechanical Engg.)
2010-11
IIIrd Year
Submitted To: Submitted By:
Ms. Neha Bhadauria Name: Alok Ranjan
Roll No. 0802940007
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ANT L B AKING SYSTE
TABLE OF CONTENTS:-
1.AN INT ODUCTION TO ANTILOCKB AKING........
1.1What is an ABS?
1.2 History
2.HOW DO ABSs WORK?
3.HOW SHOULD I DRIVE AN ABS-EQUIPPED VEHICLE DURINGROAD TESTS?4.THEORY.4.1 Electronic Control Unit (ECU)
4.1.1 ModulatorValves
4.1.2 Wheel Speed Sensors
4.1.3 Declaration sensor
4.1.4 Actuator:-
5.ABS TROUBLESHOOTING.6.WHAT ARETHE FEATURES AND BENEFITS OF ABS.7.DISADVANTAGES.
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1. AN INTRODUCTION TO ANTILOCKBRAKING:-This section reviews several basic antilock braking system (ABS) concepts.
When you complete this section, you should be able to answer the following
questions:
What is an ABS?
Whyareantilockbraking systems (ABSs) standardonmostnewcommercial
vehicles?
Howdoes an ABS work?
Whatarethemajorfeatures and benefits of ABSs?
How should I drivean ABS-equippedvehicleduringaroadtest?
1.1 What is an ABS?Antilock braking systems (ABSs) are electronic systems that monitor and
control wheel slip during vehicle braking. ABSs can improve vehicle control
during braking, and reduce stopping distances on slippery (split or low
coefficient of friction) road surfaces by limiting wheel slip and minimizing
lockup. Rollingwheels havemuchmoretractionthan lockedwheels. Reducingwheel slip improves vehicle stabilityandcontrolduring braking, since stability
increases as wheel slip decreases.
ABSs can be applied to nearly all types of vehicles and canbe successfully
integrated intohydraulicandairbrake systems (includingairoverhydraulic.
Antilockbrake systems addresses twoconditions relatedto brakeapplication;
wheell p and vehi le di ecti nal control.
The brake slowtherotationofthewheels, but it is actuallythe friction between
the tireand road surface that stops thevehicle.Without ABS when brakes are
appliedwithenough force to lock thewheels, thevehicle slides uncontrollably
becausethere is notraction betweenthetireandroad surface.Whilethewheels
are skidding, steeringcontrol is lostas well.
An antilock brake system provides a high level of safety to the driver by
preventingthewheels fromlocking,whichmaintains directional stability.
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.
1.2 HISTORY:-
1929 A ti-l b ing s st s f irst l p f r ircraft b GabrielVoisin,
1950 Dunlo 's Maxaretintroduceda s stemand still inuseon someaircraftmodels
1960 A full mechanical s stemused in the FergusonP99 racing car the Jensen FF
and the Ford Zodiac, but saw no further use; the s stem proved expensive and, in
automobileuse, somewhat unreliable
1964 Limited formof AB in Austin 1800,utili ingavalvewhichcouldadjust front to
rearbrake forcedistributionwhenawheel locked
1971 Chrysler, and Bendix Cor oration, introduced 97 Imperial. Called"Sure
Brake",
1971 AB S stems basedMercedes design were later introduced on other cars. GM
introduced the "Trackmaster" ABS on theirCadillacmodels
1975Fordalsointroduced ABS on the LincolnContinental MarkIII and the Ford LTD
stationwagon,called "Sure Trak
1978 Bosch and Mercedes-Ben introduced the first completel electronic 4-wheel
multi-channel ABS s stemin trucks and theMercedes-Ben S-Class
1988 BMW became the world's first motorcycle manufacturer to introduce an
electronic/hydraulic ABS system, this on theirBMW K 00
1992Honda launchedits first ABS system, this on the ST 00 Pan uropean
1997Suzuki launchedits GSF 00SA (Bandit) with ABS
Today ABS has becomea standarde uipment even forsmall cars
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2 . HOW DO ABSs WORK?
An ABS consists of several key components: electronic control unit (ECU), wheel
speed sensors, modulator valves, and exciter rings. Heres how these components
worktogether:
1.Wheel speed sensors constantlymonitorand sendelectrical pulses totheECU ata
rate proportionaltothewheel speed.
2. When the pulse rates indicate impending wheel lockup, the ECU signals the
modulator valve(s) to reduce and/or hold the brake application pressure to the
wheel(s) in question.
3.TheECU thenadjusts pressure, seekingonewhichgives maximum brakingwithout
riskingwheellockup.
4.WhentheECU acts tomodulatethe brake pressure, itwillalso (onmostvehicles)
turnofftheretarder(if soequipped) untiltheriskoflockup is over.
5. The ECU continually checks itself for proper operation. If it detects a
malfunction/failure intheelectrical/electronic system, itwill shutdownthat partofthe
ABS affected bythe problemortheentire ABS dependinguponthe systemandthe
problem.Whenthis happens,the ABS malfunctionlamp light.
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3. HOW SHOULD I DRIVE AN ABS-EQUIPPED VEHICLE DURINGROAD TESTS?
It is theconsensus of brakeexperts thatdrivers should brakean ABS-equippedvehicle
justas theywould brakeanon- ABS equippedvehicle.The properbrakingtechnique is
to maintain a steady, modulated brake application. Modulated, in this case, means
applyingonlythe pressurerequiredtoachievethedesireddeceleration. Donot slamon
the brakes tomake speedcorrections orroutine stops.
When operating on slippery surfaces, with or without an ABS, it is strongly
recommended that drivers depress theclutch when braking. Engine braking itself can
causedrivewheels to slip. Usually,anyretarderwillautomatically bedisabledwhen
the ABS is inuse.Muchofwhat is taughtabouthydraulic ABSs doesntapply toair
ABSs.Thus, its importanttorememberthe following:
Brakeas ifno ABS is present,withamodulatedapplicationas described previously.
Unless certainthattheentirecombinationvehiclehas aworking ABS,dont stomp on
the brakes ina panic situationoneormorewheels couldlockandcausethevehicleto
jackknife.Eventhen, becareful becauseyoucan stilljackknifeor losecontrol ifthe
vehicle is travellingtoo fast.
Donotexpect to feel the brake pedal pulsingorhearstrange sounds when the ABS
activates onair-brakedvehicles.Thesevehicles donottransmit pulsing pressuretothe
drivers footandthedriverprobablywillnothearthe systemcycling.
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4. THEORY:-
y If the driver brakes very hard it can occur that the maximum static friction is
surpassedand thewheels lose theirgripand begin slidingfriction.
The amount of traction which can be obtained for an auto tire is determined by the
coefficient of static friction between the tire and the road. If the wheel is lockedand
sliding, the forceof frictionis determined by thecoefficient ofkinetic friction.
A tire that is just on the verge of slipping produces more friction with respect to the
road than one which is locked and skidding. So locked wheels are less effective in
stoppingonaroad.But ingravel, sandanddeep snow, lockedwheels dig inand stop
thevehiclemore quickly. A locked tireallows a small wedgeof snow to buildup ahead
ofit whichallows it to stop ina somewhat shorterdistance thanarolling tire.
When tire does not slip, it will roll only in the direction it turns. But once it skids,
regardless of the angle of the front wheels, the vehicle continues to skid inwhatever
directionits momentum sends it until eitherthedriverreleases the brakes.
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5. ABS COMPONENT DESCRIPTIONS & OPERATION:-
Whenwecomplete this section,we shouldunderstand the purposeand functionof
all major ABS parts including: the C , the modulator valve, the wheel speed
sensor, ABS malfunction/indicatorlamp, ABS diagnosticcomponents,andtraction
control.
Modernantilockbraking systems all feature the followingmajorcomponents (See
Fig. 1 on page 9 fortypical system):
Electronic Control Unit (ECU)
Modulator Valves
Wheel S eed Sensors ( icku and exciter)
Diagnostics
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5.1 ELECTRONIC CONTROL UNIT (ECU):-
The ECU processes all ABS information and signal functions. It receives and
interprets voltage pulses generated bythe sensorpickup as theexciterteeth pass by,
anduses this informationtodetermine:
impendingwheellock-up and
when/how to activate the ABS modulator valves. The ECU connects to the
following ABS components: wheel speed sensors, ABS modulator valves, power
source,ground,warninglamps, blinkcode switch, J1587* diagnosticconnector, and
retarder control device (usually by relay or the J1 22**/ J1 3 *** datalink.) The
ECU alsomakes self-diagnosticchecks duringnormaloperation.
During braking, the ECU uses voltage pulses from each wheel speed sensor to
determine wheel speed changes. If the ECU determines that the pulse rate of the
sensedwheels indicates imminentlock-up, itcycles the ABS modulatorvalves
tomodify brakeairpressureas neededto providethe best braking possible.
TheECU sends signals tothe ABS malfunction indicatorlamp orblinkcodelamp to
communicate ABS faults. Italso sends signals to the retarder control to disengage
theretarderwhenthe ABS is working.Whenthe ABS stops modulatingthe
brake pressure,theECU permits retarderuseonceagain.
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5.1.1 MODULATOR VALVES :-ABS modulatorvalves regulate theairpressuretothe brakes during ABS action.When
notreceivingcommands fromtheECU,themodulatorvalveallows airto flow freelyand
has noeffectonthe brake pressure.TheECU commands themodulatorvalvetoeither:
changetheairpressuretothe brakechamber,or
hold the existing pressure. However, it cannot automatically apply the brakes, or
increasethe brakeapplication pressureabovethelevelapplied bythedriver.
The modulator valve typically contains two solenoids.The modulator valve and relay
valvemay be incorporated intoa singleunit.Themodulatorvalvemayalso be separate,
inserted into the service line to the brake chamber(s) after any relay valve, located as
closeas practicabletothechamber(s) itself.Whenthemodulatorvalve is separate, ithas
tocontrolmoreairflowand,therefore, includes two largerdiaphragmvalves whichare
controlled by the solenoids. Itusuallyhas three ports: the supply port, thedelivery port
andtheexhaust port.
The supply portreceives airfroma quickreleaseorrelayvalve.
Thedelivery port sends airtothe brakechambers.
Theexhaust portvents airfromthe brakechamber(s).
Typically,whenanECU controllinga separatemodulatorvalvedetects impendingwheel
lockup, it activates the solenoids to close the supply port and open the exhaust port.
Whenenoughairis ventedto preventwheellockup,theexhaustvalvewillcloseandthe
ECU willdependingonthe situationeither:
keep the supply portclosedtomaintainexistingpressure,or
open the supply port to allow brake application pressure to increase and repeat the
cycle.
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ABS IN MARUTI SX4 ZXI
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modulators
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ARRANGEMENT OF TOOTH WHEEL,SENSOR AND ABS SENSOR PICKUP
CABLE.
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Now the um send a ressure to tyres by hydraulic brakelines so that the braking is
controlled now.
5.1.3 DECELARATION SENSOR:-
A deceleration sensorfordetectinga threshold level ofdecelerationindicativeofavehicle
collision, comprisinga pair of sensor masses in the form of pendulums,a spring-loaded
firing pin,a pairof trigger levers whichindividuallyhold the firing pininadormant state
as longas theyareheld by the sensormasses in theirneutral states but can beindividually
disengaged from the sensor masses by the motion of the sensor masses as a result of
detecting a deceleration level greater than the threshold level. Since the firing pin is
released only when both the trigger levers are released from their neutral states, the
reliability of the dormant state of the firing pin is assured. To the end of improving the
reliabilityof theactivationof the firing pin, the firing pinmay be spring-loaded bya pair
of springs in sucha mannerthat eitherspring is sufficient fortheactivationof the firing
pin.
The purpose of the invention is to improve and upgrade the existing automobile brake
system.Currently,whena motorist pushes the foot brake in thecar todeceleratea Light
mitting Diode (L D) indicatormountedon the trunkandin therearwindows ofavehicle
lights up to indicate slowing down and stopping. In most vehicle L D systems, the
distinction between a deceleration, hard braking, and a stop cannot be indicated or
ECU
PROCESSESTHE DATA AND SEND A ACTION TO MODULATOR AND PUMP
SENSORPICKUPCABLE
SEND DATA TOECU
SENSOR
SENSESTHESPEEDOF TOOTH WHEEL
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differentiated. Thegoal of the invention is tocreatea braking indication system that will
demonstrate how fast a car is decelerating with L D arranged in a fashion to turn on
proportional to theamount of pressureapplied to the brake. Once pressure is applied, the
brakes are applied and the brake light will let the vehicle behind know how quickly the
vehicleis slowingdown by showinganapproximationusing the L Ddisplay. Thereforeif
adriveris to lightly tap onhis brakes, the brakeindicatorwill light a small amount of L D
to symboli e slowingdown but not stopping. Adversely,ifadriverslams on the brakes,
an additional complete row of brake lights will illuminate to indicate you need to brake
hard or consider an evasive action to avoid collision.
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5.1.4 ACTUATOR:-
An actuator is a mechanical device for moving or controlling a mechanism or
system. It takes energy, usually transported by air, electric current, or liquid, andconverts that into somekindofmotion.
ASSEMBLY OF ACTUATORS TO PUMP
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LINE DIAGRAM OF ASSEMBELY OF ACTUATORS & ECU
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AN ACTUATOR IN MARUTI SX4 (ZXI)
6. ABS Troubleshooting:-1. General Diagnostic Princi les
Ste p : Verify the problemordriverconcern.
Ste p : Perform preliminarychecks.
Step : Referto serviceinformation.
Step 4: Performelectrical,electronicandairsystemchecks.
Step 5: Findandisolate problem.
Step 5a: Reexaminecomplaint
Step 6: Repairandverify
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Step 7: Clearfault codes.
Step 8: Implement any possible preventivemeasures.
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6. WHAT ARE THE FEATURES AND BENEFITS OF ABSTable lists themajorfeatures and benefits offered by ABSs:
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7. DISADVANTAGES:- Increased braking distances under some limited circumstances (snow, gravel, "soft"
surfaces).
Creation of a "false sense of security" among drivers who do not understand the
operation,andlimitations of ABS.
Theanti-lockbrakes aremore sensitiveonthedampercondition.the influenceofthe
worn components on the performance of the vehicle with anti-lock brakes is more
significantthanwithoutanti-lockbrakes,the stoppingdistancewithdefective shocks
is bymeters longerforthe presented simulation scenario.