1. principle of exhaust gas turbocharger
TRANSCRIPT
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1. PRINCIPLE OF EXHAUST GAS TURBOCHARGER
In a turbocharged engine, the exhaust gas which would normally be wasted, is used to drive a turbine. The turbine in turn drives a compressor, which draws in air and compresses it and supplies it at a higher pressure to the engine. Due to higher air availability and by supplying more fuel, engine power output can be increased. Higher air availability helps in better combustion, thus leading to reduced fuel consumption and less emission.
Advantages Of Turbocharger
Lowerfuelconsumption Bettertorque characteristics
Lower engine noise Lower emission
Lower weight and a smaller engine package
Reduced power loss at highaltitude
As a result, turbochargers contribute significantly to the protection of the environment and better utilization of energy resources.
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2. CONSTRUCTION & FUNCTION OF A TURBOCHARGER
Turbocharger (TC) primarily comprises of a compressor section and a turbinesection.Theturbineandcompressorwheelsaremountedona commonshaft,hencetheyrotateasasingleunit.Thissub-assemblyis known as the rotor assembly. The rotor assembly is supported by journals placed inside the central housing.
2.1 TurbineSection
Turbine section consists of the turbine wheel and turbine housing. The pressure energy available in the exhaust gases is converted into Kinetic energy by the turbine housing and is used for rotating the turbine wheel.
2.2 CompressorSection
The compressor consists of the compressor wheel and compressor housing. The compressor wheel draws in air axially and delivers it radially at a higher velocity. The compressor housing converts higher velocity air into higher pressure.
2.3 Central Housing
The central housing consists of all the supporting & sealing components required for the rotorassembly. Journals & thrust plate for supporting rotor assy., and the lubricating oil passages for oil supply&drain.Pistonringsforsealing.
TurbineHousing
TurbineWheel
Piston rings(sealing rings)
Oil feed
Oil drain Heat shield
Axial / Thrustbearing
Radialbearings
Compressorhousing
Compressorwheel
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3. TURBOCHARGER TECHNOLOGY3.1 Waste Gated Turbocharger
For reasons of improved TC response, turbine housing with a smaller cross sectional area is chosen such that sufficient boost pressure is available at lowerenginespeeds.Partof theexhaust gas isby-passedoncetherequiredboost pressure is reached. This is achieved by opening a valve, operated by a spring loaded diaphragm (actuator assembly) with the help of boost pressure available in the compressor housing or with the help of external vacuum supply.3.2 Variable Turbine Geometry (Vtg)The turbine flow cross-section varies in accordance with the engine ECU demand by variable guide vanes placed in the exhaust gas flow area of the turbine housing. As a result of continuous turbine cross section adjustment to the engine airflow
Actuator assembly /Waste gate
requirements, high engine torque at low speeds and with adequate control strategy ensure a significant improvement of dynamic performance of vehicle. Guide vane control is mostly electronic through a vacuum regulated actuator.3.3 R2S Turbocharger
Regulated two stage turbocharger (R2S). This system uses one low pressure turbocharger and one high pressure turbocharger i.e. two turbochargers for one engine. This technology helps in increasing the engine’s specific power output (power to weight ratio) and also helps in downsizing the engine while meeting the performance requirement.
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4. NEEDS OF A TURBOCHARGER• Turbocharger components are made from special materials, processesandareprecisionbuilttoworkunderextremeoperating conditions.• However turbocharger needs ADEQUATE CLEAN ENGINE OIL & CLEAN AIR for its proper performance and extended life.
4.1 WHY A TC NEEDS THEM ?• TCrotorassemblyrotatesfrom1,00,000to2,50,000RotationsPer Minute(RPM).• The clearances between the rotor and the journal are extremely small and the parts are machined to very close tolerances (around 0.005 mm).• TCusesfullyfloatingjournals,thatrotateathalfthespeedofthe rotor assembly.• Filteredoilattherequiredpressureisessentialtolubricateandcool the journals.• TheTCcomponentsarebalancedtoveryfinebalancinglimits.• Air / gas entering the compressor and turbine housing travels at very high speeds.
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5. GUIDELINES FOR TURBOCHARGER USEThe engine manufacturer’s recommendations for operation and maintenance shall be authoritative for the operation of turbocharged engine.Specialattentionshouldbepaidtothefollowing:
5.1 OPERATION RECOMMENDATIONS5.1.1 DO NOT ACCELERATE THE ENGINE IMMEDIATELY AFTER START• Acceleratingtheengineimmediately after start can make the TC to operate at very high speeds with inadequate lubrication which will lead to reduce TC service life.• Engine should not be put under full load immediately after start, it should run at idling speed for a minimumtime(60seconds).
5.1.2 BEFORE SWITCHING OFF THE ENGINE
Allow the engine to run at idle for at least 60secondsbeforetheengineisswitched off.Idlingwillreducetherotorspeedand heat transfer thus ensuring longer TC service life.
Do not accelerate theengine immediately
after starting
Allow the Engine toidle for some time
before it is stopped
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6. TURBOCHARGER INSTALLATION AND STARTING PROCEDURE
6.1 Use only the correct part number i.e. TC approved by the engine manufacturer.
6.2 CHECK THE TC VISUALLY FOR:
Externaldamages - IfTCisfounddamaged,donotuseit.
Correctorientation - IfTCorientationisnotcorrect,pleasecontactTEL / TEL ASC for assistance.
Old TC (long storage), if TC is rusted, do not use it as-it-is. Necessary cleaning,prelubricationandinspectionoftheTCisamustbeforeitsuse.Contact TEL / TEL ASC for assistance.
6.3 TC HANDLING
AsTC isaprecisionequipment, it should be handled with great care. In any case, it should not be dropped.
In case of wastegated / VTG turbocharger, don’t use the actuator control rod for liftingtheTC.
As Wastegated / VTG turbochargers comes with preset actuators, this setting should not be changed. Any changes to the actuator settings will effect engine performance.
6.4 RemovealltheprotectiveplugsfromtheTCbeforefitment.
6.5 EXHAUST CONNECTIONS
Checktheengineexhaustmanifold&itsconnectionstotheTCforcracks &distortionandarefreefromforeignmaterial i.e.coresandparticles, loose nuts, bolts, washers, etc.
Do not use actuatorcontrol rod for lifting
the Turbocharger
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The exhaust systems should be checked for blockage (damaged pipes, faultyexhaustbrake,chokedsilencer/catalyticconverteretc.,),leakages andtheirproperalignment&support.
6.6 COMPRESSOR CONNECTIONS
Clean the TC compressor outlet to engine intakemanifold connecting pipes, hoses and intercooler for residual engine oil, before new TC is fitted.
Check the connections i.e. pipes forwear, damage, correct alignment,hosesforcracks/ageing.Checkintercoolerforleaks&blockage.Checkthehoseclipsfortheirproperfunctioning.Replacewithrecommended clips wherever necessary.
Checkaircleaner,filterelementsanditsconnectingpipes,hosestothe TCarefreefromforeignmaterial.Airfilterelementsshouldbecleaned/ replaced as recommended by the engine manufacturer.
6.7 OIL INLET AND DRAIN CONNECTIONS
6.7.1Oilinletanddrainpipes,connections to the TC, should be examined for carbon deposits, cracks, distortion, etc., Pipes should be thoroughly cleaned before fitment. If found damaged, it should be replaced.
6.7.2 Ensure that recommended size of oil inletpipe&banjoboltsareused.During replacement care should be taken for proper routing and fitment to avoid excessivestressontheconnection.
Correct oil Wrong oilhole size hole size
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TURB
OCH
ARG
ER T
ROU
BLE
SHO
OTI
NG
CHA
RT
POSS
IBLE
CAU
SES
REM
EDIA
L AC
TIO
NS
Clog
gedairfi
ltere
lemen
tsCh
eck&
replacetheelem
entaccordingto
engin
emanufacturer'srecommendatio
ns
Restric
tionsin
airintaketo
TC
com
pres
sor i
nlet
Removerestric
tionorre
placetheda
maged
pa
rts i
.e. i
ntak
e pi
pes,
with
ered
hos
es e
tc.,
Restric
tionsin
TCcompressor
outle
t to
inta
ke m
anifo
ldRe
moverestric
tionorre
placeda
maged
pa
rts i
.e. p
ipe,
hos
es, i
nter
cool
er e
tc.,
Air l
eak
betw
een
air c
lean
er a
nd
TC c
ompr
esso
r / E
x. G
as le
akag
es
atth
eturbineou
tletcon
necti
ons.
Check&arrestthe
leakbyreplacing
de
fecti
vehoses,clip
s,pipes,gasketsor
tighten
theclam
ps&fa
sten
ersa
sreq
uired
Air l
eak i
n be
twee
n TC
com
pres
sor
&intakemanifold.
Check&arrestthe
leakbyreplacing
de
fectivehoses,clips,pipe
s,gaskets,
intercoo
lero
rtightenthecla
mps&
fasten
ersthe
clam
p&fasten
ersa
sreq
uired.
Fore
ign
obje
ct in
eng
ine
exha
ust
man
ifold
/ in
take
duc
t to
TC c
ompr
esso
r
Removetheob
ject&che
ckfo
rthe
cau
se/
originofthe
objecte
ntry&correctit.
Rest
ricte
d ex
haus
t sys
tem
/ chockedcatalytic
con
verter.
Removerestric
tionorre
placeda
maged
pa
rts,clean
/replacecatalytic
con
verteras
requ
ired
ComplaintEngine lacks power Black exhaust smoke Excess
iveoilconsu
mption Blue / white smoke Turbocharger noisy Oil leak from comp. Oil leak from turbine
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Exha
ust g
as le
akag
e be
fore
the
TC.
Check&
arresttheleakb
yreplac
ingd
efective
parts,gasketsortightenthefastenersasrequired.
Restric
tionintu
rbocha
rgeroil
drai
n lin
eRe
moverestric
tioninth
epipe
s,atjointso
rreplacewith
ered
hosesasreq
uired
Rest
ricte
d en
gine
cra
nk c
ase
breather/malfunctio
ning
ofcrank
caseven
tilati
onsy
stem
.
Refe
r to
engi
ne m
anuf
actu
rer's
man
ual
andremoverestric
tion(ensurefree
flow
of
gases)&re
placethede
fecti
veparts
Rotorrotati
onnotfree
due
to
thic
k oi
l slu
dge
or c
oke
in
turb
ocha
rger
cen
tral
hou
sing
Chan
geoil&oilfilter,checkEG
Rforc
orrect
operati
on,con
tactTELAutho
rised
service
centersforTCrecti
ficati
on.
Faultyfuelinjectionpum
p&injectors
&itsfi
tmenttoengin
e/faultyEC
U/
defectiveEG
Roperation.
Refe
r to
engi
ne m
anuf
actu
rer's
man
ual a
nd
replaceoradjusta
sreq
uired
Worn-ou
tvalves,piston
ring
, lin
ers,
inte
rnal
eng
ine
prob
lem
s (in
crea
sed
blow
by)
Refe
r to
engi
ne m
anuf
actu
rer's
man
ual a
nd
repa
irasre
quire
d
Dam
aged
act
uato
r ass
y., b
oost
pr
essu
re c
ontr
ol v
alve
stuc
k in
op
enposition
Repl
ace
TC O
R co
ntac
t TEL
Aut
horis
ed
servicecentersforre
ctificati
on.
Actuatorassy,.Operatin
gho
se
punc
ture
d O
R fo
und
disc
onne
cted
Repl
ace
/ con
nect
the
hose
con
tact
TEL
Au
thorise
dservicecentersforre
ctificati
on.
VGTactuatorope
ratin
gho
sefo
und
disc
onne
cted
or f
ound
pun
ctur
ed,
controlvalvedefective
Conn
ect t
he h
ose,
repl
ace
the
dam
aged
ho
se /
cont
rol v
alve
.
Turb
ocha
rger
dam
aged
RefertoTEL,Au
thorisedservice
center,analyse&
co
rrect
the c
ause
of f
ailur
e (tu
rbo
failu
re is
nor
mal-
ly du
e to
lack o
f oil,
low
oil p
ress
ure,
bad
engin
e oil
condition,fo
reign
particleentry
intoco
mpressor
/ tur
bine
inlet
). Ser
vice o
r rep
lace t
urbo
chag
er as
required.
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6.7.3 Use only the recommended gaskets forfitmentoftheTCtotheengine.
Do not apply gaskets sealant (Shellac, Anabond, Grease, etc.,) at the oil inlet and compressorinletconnections.
Do not use thread sealant in the oil supply line.
6.7.4 Beforestartingtheengine,fill-upthe oil feed hole of the TC with clean engine oil to ensure lubrication during engine start-up. Oil filter should be filled with clean engine oil to minimize oil reaching timetoTC.
Replace the engine oil and oil filter, if necessary (adhere to engine manufacturer’s recommendation for correct grade and change periodicity)
Disconnect the TC actuator operating switch / hose (for VTG TCs) during first starting.6.7.5 Disconnect the oil drain joint between turbocharger and crankcase. Cranktheenginewithoutstarting,untiloil flow is observed in the turbocharger oil drain line. A funnel can be used to return oil to the crankcase. Reconnect the oil drain joint.6.7.6 Check the engine oil pressure. Do not run the engine, if oil pressure is found less than the one recommended by the engine manufacturer.
Connect the TC actuator operating switch / hose (for VTG TCs).
Oil in the filter
Do not run the enginewith low engine
oil pressure
Do not apply sealant inGaskets
Pre oil the turbochargerbefore fitment
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6.8 ENSURE NO LEAKAGEWith the engine in running condition, check oil line, air and gas connectionsforleakageandfortheirproperfunctioning.Checkoilinletandreturnlineconnectionforleakages.Ensure that the air cleaner to TC connections are intact. Check air leakages at compressor outlet to inlet manifold.Check exhaust gas leakage at exhaust manifold and at the turbine housing joints.The most common reason for NOISE complaint is small leakage of exhaust gas or compressed air.
CAUTION
Stay away from running Turbocharger (at engine higher RPM)
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7. TC VISUAL INSPECTION PROCEDURE
Check the compressor wheel for Damage.
Damaged – Not O.K Not damaged – O.K
Check the compressor wheel for rubbing with housings.
Rubbing marks – Not O.K No rubbing marks – O.KChecktheshaftforfreerotation.
Nofreerotation–NotO.K Freerotation–O.K
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7.1 PNEUMATIC ACTUATOR ASSEMBLY CHECKING PROCEDURE
ChecktheTCactuatorassemblyforitsproperfunctioningi.e.checkfor damages,tampering,looseoropenconnections.
Checktheshaftforfreerotation.
Excess play – Not O.K Normal play – O.K
NOTE
Fallowthesameinspectionprocedureforturbinesidealso.
3OK
L pipe breakage
Hose puncture
Link welding failure
Flap Open(for pressuretype only)
Control rod damaged
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7.2 VTG TC VACUUM ACTUATOR CHECKING PROCEDURE
Thenormalworkingcondition:
Withtheengineisswitched-off,TCactuatorwillbeinOPENconditioni.e.Actuator control rod length will be maximum.
Whentheengineisswitched-on(whileengineinrunningcondition),TCactuatorcontrolrodwillbeinclosedconditioni.e.Actuatorcontrolrodlength will be minimum.
During theengineoperation theTCactuator control rodmoves freelywithoutrestriction.
VACUUMPUMP
EGRVALVE
ECU
CONTROLSWITCH
ENGINE RPM METER
1
23 4
5
6
7
Engine Switch ‘ON’Condition
Engine Switch ‘OFF’Condition
VACUUMRESERVOIR
VTG TC Vacuum Actuator Not OK:
Symptoms: Vehicle speed is not O.K, Check Engine light is ON.
Diagnosis on the Vehicle:Connecttheenginediagnosticandcheckfor fault code (Ex.: Engine airflow deviation - Not O.K)
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Checks on vehicle:
Thevacuumhoses forcorrectfitment,Open/damagedhoseswill causeactuatormalfunctioning.
Switchcontrollingvacuumsupplytoactuatorforproperfunctioning.
Thevacuumpumpisfunctioningcorrectly.
Sufficientvacuumsupply istheretoTCactuatorwhiletheengineis in runningcondition.
Checks on TC:
Check if the actuator control rod is proper (ensure that it is not tampered),theadjustingnutsarein place, the control rod is not damaged, rusted, excessively worn-out.
Move the control rod with handconfirmitsmovement is free.
Remarks: If all checks on vehicle found O.K and the TC actuator operation is not O.K i.e. the actuator control rod does not move up when theengine is switched-on andmovesdownwhen theengine is switched-off OR the TC actuator control rod movement is not free - Replace the TC.
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Complaint: TC Damage
Observations: Blue colour formation on the shaft journal area. Seizure / excessive wear on the journals
Causes: Lack of oil supply
Complaint: TC DamageObservations: Journal oil holes closed partially. Discolouration / glazing marks on shaft journal contact area
Causes:Insufficientoilsupply/Low oil pressure
8. SERVICE RECOMMENDATIONS
PleaseconsultTELASCforanyservicerequirementofaturbocharger,as they only will have necessary tools & equipment, trainedmanpower, genuine parts for proper service andwill offer support for its correct installation&maintenance.
Fordetailsvisit:www.turboenergy.co.in
9. TURBOCHARGER FAILURE ANALYSIS
Years of experience has shown that the largest percentage of turbocharger failures are caused by lubrication problems such as lack of oil, low oil pressure and dirt in oil.
Thesecondlargestpercentageiscausedbyforeignparticleenteringthe compressor / turbine housing sides.