Antolock Braking System

8/8/2019 Antolock Braking System

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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.

Antolock Braking System

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