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Ignition Technology Diesel Cold Start Technology Cooling Sensors
Technical Information
No. 04
®
Perfectionbuilt in
All about glow plugs
The diesel engine 3
Self-regulating pencil type glow plugs 5
The Instant Start System (ISS) 9
BERU – Lead innovator for the use of PSG pressure sensor glow plugs 10
BERU – Ceramic glow plug (CGP) 10
Cheap designs - something you should do without 12
BERU quality 11
Causes of failure in glow plugs 13
Workshop tips 14
Function 3Coldstart 3Injectionsystem 4
Requirementsonamodernglowplug 5Designandfunction 6Post-heatingglowplugs(GN) 7/8
Systemconcept 9Electroniccontrol 9
Glowplugtestdevice:Testingwithoutremovingtheplugs 14Howtostartthedieselenginequicklyandsafely 14Torques 15BERUreamer:foraquickandreliablecleaningofthecylinderheadbore 15
Contents
2
Function
Cold start
The diesel engine
Dieselenginesarecompression-ignitionengines,whichmeans:theinjectedfueligniteswithouttheneedforanignitionspark.Thecombustioncycleistriggeredinthreesteps:
1.First,cleanairistakenin.2.Thisairiscompressedto30–55bar–duringthisprocess, itwillheatupto700–900°C.3.Dieselfuelisinjectedintothecombustionchamber.Thehigh temperatureofthecompressedairtriggersauto-ignition, internalpressurestronglyincreasesandtheenginedoes itswork.
Comparedtospark-ignitionengines,compression-ignitionenginesrequirecomplexinjectionsystemsandenginedesigns.Thefirstdieselengineswerenotactuallyveryconvenientorsmooth-runningdriveunits.Duetothehardcombustionprocess,theymadealotofnoisewhencold.Typicalcharacteristicsincludedalowerpower-to-weightratio,alowoutputperliterdisplacementaswellasaloweraccelerationperformance.Throughcontinuousdevelopmentoftheinjectiontechnologyandtheglowplugs,itwaspossibletoeliminateallthesedisad-vantages.Today,thedieselengineisconsideredanequivalentorevenbetterpowersource.
Theterm„coldstart“describesallstartprocessesoccurringwhiletheengineandthemediainvolvedhavenotreachedoperatingtemperature.Thelowerthetemperature,thelessfavorablearetheconditionsforaquickignitionandcomplete,environmentallyfriendlycombustion.Certainsuppportingmeasuresareusedtoassistduringthecoldstartandsothatstartingwillnotbeunacceptablylongorevenimpossible.Thesecompensateforthepoorerstartconditionswhileinitiatingawell-timedandevenignitiontoensurestablecombustion.
Theglowplugisonecomponentthatassistsduringcoldstart.Itcreatesidealignitionconditionsfortheinjectedfuelthroughelectricallygeneratedthermalenergythatisbroughtintothecombustionchamber.Itisindispensableasascoldstartaidforengineswithadividedcombustionchamber,inordertoensurethatthesecanstarteveninthefrequentlyoccurringtempe-raturerangeof10–30°C.Sincethestartqualitydeterioratesconsiderablyatbelowfreezingpoint,theglowplugisalsousedascoldstartaidfordirect-injectiondieselengines.
3
The diesel engine
Injection systems
Dependingonthedesignandarrangementofthecombustionchamber,adistinctionismadebetweenthefollowingthreeinjectionsystemsindieselengines:
1.Antechambersystem2.Turbulencechamberprocess3.Directinjection
Glowplugsarerequiredforallsystems–toensurethattheinjectedfuelcanevaporateandthefuel-airmixturecanigniteonthehotsurfaceoftheplug.
ANTECHAMBER SYSTEMInthissystem,thecombustionchamberisdividedintotwo:anantechamberandthemainchamber.Theseareconnectedwithoneanotherbyseveralbores(injectionchannels).Duringthecompressionstroke,apartofthecompressedairisforcedintotheantechamber.Shortlybeforereachingthetopdeadcentre,thefuelisinjectedthroughanozzledirectlyintotheantechamberoftherespectivepiston.Thisiswheretheinjectedfuelispartiallycombusted.Thehightemperaturesgeneratedensurearapidincreaseinpressure.Theentirecontentsoftheantechamberarethusblownthroughtheinjectionchannelsintothemaincombustionchamber,wheretheactualcombustiontakesplace.
TURBULENCE CHAMBER PROCESSThesphericalturbulencechamberisarrangedinthecylinderhead,separatelyfromthemaincombustionchamber.Maincombustionchamberandturbulencechamberareconnectedbyawide-diameterinjectionchannel.Duringthecompressionstroke,theinjectionchannelintheturbulencechambercausesintensiverotationoftheintakeair.Thedieselfuelisinjectedintothisairturbulence.Combustionstartsintheturbulencechamberandthenspreadsthroughintothemaincombustionchamber
DIRECT INJECTIONIndieseldirectinjection(fuel-airintroduction),thefuelisinjectedathighpressurethroughthemultiple-holenozzleintothehighlycompressedintakeairforatomization;duringthisprocess,thespecialpistoncrowndesignhelpswithmixtureformation.Duringstart,thecoldintakeairisveryquicklyheatedupduetothehighcompressionpressure.Theheatingelementprojectsintothemaincombustionchamber.Inprinciple,theglowplugindirectinjectionengineshasthesamefunctionasinthechamberengines:ithelpswithignitionduringthestart.Theheatingelementofamodernglowplugreachesatemperatureofover1,000°Cwithinonlyafewseconds.
Withcoldstarts,thesituationisgenerallyasfollows:thecoldairthatisdrawninproduceslowertemperaturesattheendofthecompressionstage.Whiledriving,thetemperatureofthecom-pressedairisadequateforself-ignition.However,itisnotsufficientwhenstarting,especiallywithlowoutsidetemperatures.Butitisthelowstartingrevsthathavemoreseriousconsequences.Duetothelongdwelltimeofthecharge,thelossoftemperatureandpressureismuchgreaterthan,forexample,whenidling.
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1 | Injection nozzle
2 | Glow plug
3 | Antechamber
4 | Turbulence chamber
5 | Combustion chamber
1
Self-regulating pencil type glow plugs
SHORT HEAT-UP TIMEGlowplugsmustprovideahightemperaturewithinasshortatimeaspossibletoassistwithignition–andtheymustmaintainthistemperatureregardlessoftheambientconditions,orevenadjustthetemperaturedependingonthem.
SMALL SPACE REQUIREMENTPassengercardieselengineswithantechamberorturbulencechamberinjectionanddirectinjectionversionsusing2-valvetechnologyusuallyhaveenoughspaceavailableforinjectionnozzlesandglowplugs.However,inmoderndieselengineswithcommonrailorpump-nozzleinjectionsystemsand4-valvetechnology,theavailablespaceisveryrestricted.Thismeansthatthespacerequiredfortheglowplugmustbereducedtoaminimum,resultinginaverythinandlongshape.Today,BERUglowplugswithglowtubediametersreducedto<3mmarealreadyinoperation.
PRECISE ADAPTATION TO THE COMBUSTION CHAMBERIdeally,theglowrodshouldbesituatedpreciselyattheedgeofthemixturevortex-however,itmuststillprojectsufficientlydeepintothecombustionchamberortheantechamber.Onlythenisitabletointroducetheheataccurately.Itmaynotprotrudetoofarintothecombustionchamber,asitwouldotherwiseinterferewiththepreparationoftheinjectedfuelandthusthepreparationofthemixtureforanignitablefuel-airmixture.Thiswouldresultinincreasedexhaustgasemissions.
SUFFICIENT GLOWING VOLUMEApartfromtheglowplug,theinjectionsystemisofparticularsignificanceintheenginecoldstart.Onlyasystemthathasbeenoptimizedintermsofitsinjectionpoint,quantityandmixturecompositioninconjunctionwiththecorrectpositionandthermalratingoftheglowplugwillensuregoodcoldstartperformance.Evenaftertheenginehasbeenstarted,theglowplugmaynotbe„blowncold“bytheincreasedairmovementinthecombustionchamber.Veryhighairspeedsareinparticularpresentinantechamberorturbulencechamberenginesattheglowplugtip.Inthisenvironment,theplugwillonlyworkifithassufficientreserves;i.e.ifsufficientglowingvolumeisavailablesothatheatcanimmediatelybebroughtonintothecold-blownzone.
TheglowplugsdevelopedbyBERUfulfillalltheserequirementsinanoptimalmanner.BERUengineersworkcloselywiththeautomotiveindustryespeciallyduringtheenginedevelopmentstage.Theresult:anenvironmentally-sounddieselquickstartin2-5seconds(inconjunctionwiththeInstantStartSystemISSamaximumof2seconds),areliablestartupto–30°C,asteadyenginestart-upthatisgentleontheengine,withupto40%lesscarbon-particulateemissionsinthewarm-upphaseforpost-heatingglowplugs(formoreinformationseefrompage7onwards).
Requirements on a modern glow plug
5
Self-regulating pencil type glow plugs
Design and function
TheBERUglowplugbasicallycomprisestheplugbody,heatingrodwithheatingandregulatingcoil,aswellastheconnectingbolt.Thecorrosionresistantglowrodispressedinthehousingsothatastobegas-tight.Theplugisadditionallysealedbyasealingringoraplasticcomponentattheconnector.Abatterysuppliestheelectricalenergyfortheglowplug.Itiscontrolledbyanelectronicglowtimecontrolunit.
HEATING AND REGULATING COILThebasicprincipleofamodernglowplugisthecombinationofaheatingandaregulatingcoilintoasinglecommonresistorelement.Theheatingcoilismadeofhigh-temperatureresistantmaterialtheelectricalresistanceofwhichislargelytemperature-independent.Togetherwiththefrontpartoftheglowrod,itformstheheatingzone.Theregulatingcoilisattachedtotheliveconnectingbolt;itsresistancehasalargetemperaturecoefficient.
Theentirecoilisfirmlypackedinacompressed,electricallyinsulatingbuthighlyheat-conductiveceramicpowder.Duringmechanicalcompaction,thepowderiscompressedsomuchthatthecoilisfittedasifitwascastincement.Thismakesitsostablethatthethinwiresoftheheatingandregulatingcoilcanpermanentlyresistallvibrations.Eventhoughtheindividualwindingsarearrangedonlyafewtenthsofamillimeterapart,nowindingshortcircuitscanbeproduced–andcertainlynoshortcircuittotheglowtube,whichwoulddestroytheplug.
Withthedifferentmaterials,lengthsanddiameters,anddiffe-rentwirethicknessesfortheheatingandregulatingcoil,itispossibletochangetheheat-uptimesandglowtemperaturesofthepluginaccordancewiththerespectiverequirementsoftheengine.
FUNCTIONDuringpre-heating,ahighcurrentinitiallyflowsviathecon-nectingboltandtheregulatingcoiltotheheatingcoil.Thelatterheatsupquickly,causingtheheatingzonetoglow.Glowingquicklyexpands–after2-5seconds,theheatingrodglowsuptoneartheplugbody.Thisadditionallyincreasesthetemperatureoftheregulatingcoilthathasalreadybeenheatedupbythecurrent.Then,theelectricalresistanceincreasesandthecurrentisreducedtoapointwhereitcannotcauseanydamagetotheglowrod.Overheatingoftheglowplugisthusnotpossible.
Iftheengineisnotstarted,theglowplugwillbeswitchedoffbytheglowtimecontrolunitafteracertainstand-bytime.
TheresistanceofthealloyusedonBERUglowplugsincreaseswiththetemperature.Itisthuspossibletodesigntheregula-tingcoilinsuchmannerthatitwillinitiallyletthroughahighercurrenttotheheatingcoilthanwhenitreachesthetargettemperature.Thetargettemperatureisthusreachedquickerandismaintainedwithinthepermissiblerangebyanincreasedregulatingeffect.
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Connecting bolt
Design of a self-regulating, fast-heating.pencil type glow plug.
Plug body
O-ring seal
Insulation disc
Round nut
Gasket
Insertion thread
Annular gap
Glow tube
Regulating coil
Insulating filling
Heating coil
Self-regulating pencil type glow plugs
Oldervehiclemodelsarenormallyequippedwithglowplugsthatonlyglowbeforeandduringthestartphase.TheycanberecognizedfromtheabbreviationGV.ModernDieselpassengercarsnormallyleavetheassemblylinewithfittedGNglowplugs.Theyareequippedwiththeinnovative3-phaseglowsystem.Thismeansthattheyglow
nbeforethestart,nduringthestartphase,nafterthestart,andnduringengineoperation(incoastingmode).
FUNCTIONTheelectronicallycontrolledpre-heatingstartswhentheignitionlockstarterswitchisoperatedandlastsforapprox.2-5secondsatnormaloutsidetemperaturesuntiltheengineisreadytostart.Thepost-heatingtimeisupto3minutesafterstartingtheenginetoreducepollutantandnoiseemissionstoaminimum.Theengineoperatingstateisregisterede.g.bymeasurementofthecoolanttemperature.Thepost-heatingprocessisconti-nueduntilthecoolanthasreachedatemperatureof70°C,oritwillbeswitchedoffafteracertaintimewhichissetintheperformancemap.Nopost-heatingwillnormallytakeplaceifthecoolanttemperaturewasalreadyhigherthanthatbeforestarting.
PROTECTION AGAINST OVERHEATINGSelf-regulatingglowplugsrestrictthecurrentflowingfromthebatterytotheplugwithincreasingtemperaturetopreventoverheating.However,whentheengineisrunning,thevoltagewillincreasetoapointwhereglowplugsthatdonotcomplywiththenewesttechnologywillblow.Besides,theplugsthataresuppliedwithcurrentareexposedtohighcombustiontemperaturesafterthestart,andarethusheatedupfromtheinsideandtheoutside.Thepost-heatingBERUglowplugsarefunctionalatfullgeneratorvoltage.Theirtemperatureincreasesveryquickly,butwillthenbelimitedbythenewregulatingcoiltoasaturationtemperaturethatislowerthanthatofnonpost-heatingplugs.
Important:OnlyGNglowplugsmaybeinstalledinaglowsystemdesignedforGNglowplugs–GVglowplugscouldbedamagedveryquickly.
Post-heating pencil type glow plugs (GN)
7
The 3-phase glow technology.
T (° C)
1.000
Phase 1
Pre-heating 2-7 sec.
Start heating 2 sec.
Post-heating approx. 180 sec.
Phase 2 Phase 3
850
Circuit design principle for a post-heating glow system with four fast-heating glow plugs connected in parallel and a tempe-rature sensor.
Three-phase alternator
Battery
Starter
Indicator lamp
Electronic control unit
Ignition lock starter switch
Self-regulating pencil type glow plugs
QUICK START IN 2 SECONDSWiththepost-heatingBERUGNglowplug,itispossibletoreducetheglowtimeto2-5seconds.Toachievethis,thedesi-gnersreducedthediameteratthefrontendoftheheatingrod.Theheatingrodthusstartsglowingquickerinthiszone.Atatemperatureof0°C,thistakesjust2secondsuntilstart.Whentemperaturesarelower,thesystemisaccordinglyadaptedtotherequirementsbytheglow-timecontrol,andglowtimewillrespectivelyincrease:at–5°Capprox.5andat–10°Capprox.7seconds.
REDUCTION OF WHITE/BLUE SMOKESo-calledwhiteorbluesmokeisemittedfromtheexhaustuntiltheidealignitiontemperaturehasbeenreached.Thesetypesofsmokeproducedaretheresultofincompletecombustionofthefuel,resultingfromtoolowanignitiontemperature.Post-heatingcausesthedieselfueltoburnmorecompletelyandwithlessnoiseduringthewarm-upphase.Smokeopacityisthusreducedbyupto40%.
ELIMINATION OF COLD-START KNOCKINGKnockingduringcold-startofadieselengineiscausedbyanincreasedignitiondelaywhentheengineiscold.Thefuelignitesabruptly,andtheengineknocks.Pre-heatingandpost-heatingofGNglowplugsensurethattheenginereachestheoperatingtemperaturequicker.Thispreservestheengine,resultsinquieterenginerunningandpreventsknocking.Thefuelwillthenbeburntmoreevenlyandmorecompletely.Moreenergyisthusreleasedandthecombustionchambertemperaturewillincreasefaster.
Technical features of the GN glow plug
nQuick-startglowpluginslimdesignnShortpre-heatingtime:onlyapprox.2-7secondsnReliablestart(evenat-30°C)nEnvironmentallyfriendly:approx.40%lesspollutantemissionduringthewarm-upphasenNoknockingnQuieterenginerunningnStartisgentleontheenginenForvehicleswithoperatingvoltagesupto14.5V
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Carbon deposits in the filter paper three minutes after the cold start. With post-heating (on the right), carbon deposits are approx. 40% less than without post-heating.
The BERU Instant Start System (ISS)
Technical features of the ISS
nReliablestartevenattemperaturesof-30°CnExtremelyfastheat-uptime:1,000°Care reachedin1-2secondsnLowpowerrequirement(inparticularimportant forengineswith6ormorecylinders)nHigherfunctionalreliabilitynControllabletemperatureforpre-,intermediate andpost-heating
nNumerousdiagnosticsfunctionsnimmediatestableidlingandwell-controlled loadtake-upnMinimisedpollutantemissionsnSpecificallydesignedfordieselengines withdirectinjectionnOn-boarddiagnostics-enabled
9
Interior structure of the self-regulating standard glow plug SR (left) and the power-optimized ISS glow plug (right).
Electronically controlled glow system ISS: Control unit and glow plugs.
The BERU Instant Start System enables key-turn start for compression-ignition engines just like that for a spark ignition engine.
System concept
Electronic control
Tomakeakey-turnstartpossiblefordieselfuelledvehiclesresemblingthatforasparkignitionengine–thatwasthegreatchallenge.ThesolutionfromtheBERUengineers:theInstantStartSystemISS.
TheBERUISScomprisesanelectronicglowplugcontrolunitandperformance-optimizedglowplugswithareducedheat-uptimeofmaximum2seconds–comparedtoapprox.5secondsforastandardglowplug(SR).Bothintheheating-upandinthesaturationphase,theyrequiresignificantlylessenergy.Powersemi-conductorsareusedinthecontrolunitasswitchestocontroltheglowplugs,replacingtheelectro-mechanicalrelayusedinthepast.Comparedtotheconventionalself-regulatingglowplugs,thewindingcombinationofthepower-optimizedglowplugoftheISSisconsiderablyshorterandtheglowingareaisreducedtoapproximatelyonethird.Indirect-injectionengines,thiscorrespondstothepartoftheheatingrodthatprotrudesintothecombustionchamber.
Whentheengineisrunning,theglowplugiscooledbythechangeinthechargeandairmovementinthecompressionphase.Thetemperatureoftheglowplugwilldecreasewithincreasedspeedforaconstantglowplugvoltageandinjectionquantity,andwillincreaseforanincreasinginjectionquantityandconstantglowplugvoltageandspeed.Theelectroniccontrolunitcancompen-satefortheseeffects:theglowplugsarealwayssuppliedwiththeoptimaleffectivevoltagefortherespectiveoperationpoint.Theglowplugtemperaturecanthusbecontrolleddependingontheoperatingstate.Inaddition,thecombinationofthelow-voltageglowplugandtheelectroniccontrolunitisusedforheatinguptheglowplugextremelyquickly.Thisisdonebyfeedingthefullon-boardvoltagetotheglowplugforapre-definedperiod,andonlythenoperatingwiththenecessaryeffectivevoltageduringsynchronizedoperation.Thenormalpre-heatingperiodisthusreducedtoamaximumof2secondsevenatlowtempe-ratures.Theefficiencyofthesystemissohighthatnotmuchmorethanthepowerrequiredbytheglowplugistakenfromtheon-boardpowersupply.AseachglowplugcanbecontrolledbyaseparatepowersemiconductorintheISS,thecurrentcanbemonitoredseparatelyineachglowcurrentcircuit.Individualdiagnosticsateachplugisthuspossible.
BERU – Lead innovator for the use of PSG pressure sensor glow plugsINTELLIGENT PRESSURE-SENSOR GLOW PLUGNewemissionlawsinEuropeandintheUSwillfurtherreducethepermissibleexhaustgasemis-sionsofdieselengines.ThethresholdsforNOxandparticulateemissions,whicharerelevantforthedieselengine,willinfuturebeupto90%lowerthanthepresentvalue.Itwillnotbepossibletocomplywiththeseemissionstandardswithconventionalsolutionsalone.
BERUdevelopershaveintegratedapiezoresistivepressuresensorintotheplug.Inviewoftheextremelyhightemperatures,vibrationsandpressureconditionsinthecylinderhead,themecha-nicaldesignoftheglowplugisanimportantsuccessfactor.Theheatingrodisnotpressedintheglowplugbody,aswasthestandardinthepast,butissupportedelasticallyasmobilecomponent,andittransmitsthepressuretoadiaphragmlocatedintherearareaoftheglowplug.Theactualpressuresensoristhuspositionedfarawayfromthecom-bustionchamberinanareawithsigni-ficantlymorefavorableambientconditions.ThermalloadonthesealremainscontrollableduetotheuseofaheatingrodfromtheBERUDieselISSquick-startsystem,whichonlyglowsatitstip.
TheintelligentPSG(pressuresensorglowplug)isalreadybeingtestedasoriginalequipmentbyVolkswagengroupandGM/Opel,andissoontobeusedinthelatestdieselenginedesigns.
FormoreinformationaboutBERUPSG–pressuresensorglowplugsreadBERUPSGbrochure.
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The intelligent PSG (pressure sensor glow plug).
Connector High-currentconnection
Measuringdiaphragm
Glowplugheatingrod
PCboardwithelectronics
Glowplugbody Gasket
The heating element consists of electrically con-ductive solid ceramic. Because this has a higher specific resistance at the surface than the supply and return conductor material, the glow rod only glows at the tip (the cap) thus reaching high temperatures faster. The glow plug contact consists of an internal and external conductor with an insulator positioned between them.
The structure of the ceramic heating rod on the BERU glow plug
Glowplugcontact
Heating
sectionCapCaparea
Externalconductor
Internalconductor
Insulator
STRONG INNER VALUESThecompositionofthematerialsiscrucialtotheperformanceofBERUceramicglowplugs.HighstrengthsiliconnitrideceramictoenclosetheelectricallyconductiveMolybdenumdisilicideinsideaninterpenetratingstructure.Thismaterialwithstandspressuresupto200barandtemperaturesupto1,300°C-allinthevariousgaseousatmospheresencounteredinthecombustionchamber(ambientair,diesel,oxygen,water).
PERFORMANCE DRIVEN TO THE TIPBesidesshortheat-uptimes,theexternallypositionedheatingroddesign,ofcoursepatented,alsoprovidesoptimizedregulation.Moreovertheplug’sheatingcapacityconcentratedatthetipoftheceramicelementrequireslessenergytogeneratethetemperaturerequiredtostarttheengine-andthususeslessfuelcomparedwithconventionalplugs.Besidesincreasingtheopera-tingreliability,theresistancewithintheregulationsystem,ensurestheBERUceramicglowplughasthebestpossibleenergybalanceateveryengineoperatingpoint.Thisalsocontributestoareductioninconsumptionandemissions.
AN ExCLUSIVE PROCESSBERUceramicglowplugsaremanufacturedonpatentedseriesproductionfacilities.Theceramicheatingelementisproducedinanextrusionandinjectionmoldingprocess.Thisisfollowedbyprocessestorelieve,sinterandhardenthemtoproducethetighttolerancesrequiredbeforetheycanbefittedintothemetalbodies.Thisrequiresseveralgrindingprocedures,andduetotheextremehardnessandstrengthofthematerials,thegrindingmustbeperformedwithdiamondtools.Theceramicheatingrodcontactisproducedinspecialhigh-temperatureproceduresoverthefullsurface.Thisachieveshighresistancecapacityagainstoscillationsandtemperaturechan-ges.Withthecombinationofhigh-strengthmaterial,innovativeconstructionandthelatestpro-ductionprocesses,BERUceramicglowplugsofferoutstandingfeatures.
BERU – Ceramic glow plug (CGP)
The microstructure of the BERU glow plug ceramic with strengthening small silicon nitride rods and white Molybdenum disilicide grains, which form the electrically conductive, three-dimensional structure.
BERU – Lead innovator for the use of PSG pressure sensor glow plugs
BERU glow plugs: Fivefold safety for maximum quality
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Glowplugheatingrod
1. DESIGNED IN CLOSE COOPERATION WITH CAR MANUFACTURERSAsdieselcold-startspecialistanddevelopmentpartneroftheautomotiveindustry,BERUhasnotonlybeeninvolvedintheglowplugdesignfromthebeginning,butwasalreadypresentandinvolvedduringthedevelopmentofnewengines.Itwasthereforepossiblepreciselytocoordinatetheinstallationposi-tionoftheglowplugwithintheengine-andBERUengineersknowexactlywhatparametersareparticularlyimportantorwhatperformancereservesmustbepossessedbytheglowplugunderdevelopment.
2. MANUFACTURED ACCORDING TO ISO STANDARDSBERUglowplugsaredesignedincompliancewithISOStandard7578and6550.Thesespecifythedimensionsandtolerancesofthegeometry,thesealingangle,thewrenchsize,theheatingroddiameter,etc.
3. DEVELOPED ACCORDING TO THE PRODUCT SPECIFICATIONS OF THE AUTOMOTIVE INDUSTRYBERUglowplugsfulfiltheproductspecificationsofautomotiveindustry,whichvaryfromonevehiclemanufacturertothenext.Thus,forinstance,between10,000and25,000cyclesarerequiredforcontinuousoperation.
Furthermore,BERUglowplugsmustsurvivetestrunsinthecoldchamber.Inaddition,testsaremadeonresistancetoenviron-mentalinfluences,contactmedia,additivesandenginecleaners.
4. SUBJECTED TO SPECIAL BERU TESTSBERUglowplugsundergospecialtestrunsthathavebeenadaptedtothepracticalrequirementsforeverydayoperationandfortheworkshop,forinstancethroughsimulationofcon-nectorpull-offforcesorquickoverloadtests.Thetestpersonnelareunrelentinginthesequickoverloadtests:Everytestspecimenmuststillbefullyfunctionalevenafter3,000cycles.
5. MANUFACTURED ACCORDING TO THE LATEST PRODUCTION METHODSThemanufactureoftheextremelylongandslimmodernglowplugsfordirectinjectiondieselenginesbringsparticularchal-lenges.Thediameteroftheglowtubemustbeexactlyadaptedtothecombustionchamber.Apreciselydimensionedlengthoftheglowtubemustprojectintothecombustionchamber–onlythencanitbeensuredthattheturbulencewillnotgenerateanyadditionalharmfulemissions.Thetemperaturepropertiesoftheglowplugmustalsobeaccuratelysuitedtothecombustionchamberdesign–andthecurrentconsumptionoftheglowplugsmustbepreciselyadaptedtotheexistingon-boardpowersupply.Onlythelatestproductionfacilities,suchasthoseope-ratingatBERU,providetheconditionsformanufacturingtheseslimglowplugstothedesiredquality.
2-COIL OPTICS, BUT ONLY 1-COIL TECHNOLOGYOnlya2-coilglowplugachievestheshortheat-uptimeandtemperatureresistancedemandedbycarmanufacturers.However,asthesecondcoilisnotimmediatelyvisiblefromtheoutside,somemanufacturerssparethemselvestheso-calledregulatingcoil.Thelackoflimitationoftheglowcurrentputsexcessivestressonthebatteryduringstart–andsincetherequiredheatingisnotachievedwithintheprescribedtime,thevehiclewillnotstart,oronlywithdifficultly.(SeeFigure3)
HEATING ROD FILLING USING LOW-QUALITY INSULATING POWDERInsteadofthemagnesitepowderthatisusedbyBERU,whichiscompressedanddriedbeforefilling,cheapglowplugsnormallyemployloose,insomecasescontaminated,insulatingpowderthatisputinwithoutdrying.
Fatalconsequence:Duringfirstglowprocess,thepowderexpandssignificantly,andtheglowtubeinflates.Theglowplugscanthenonlyberemovedbydisassemblingthecylinderhead!(SeeFigure9)
HEATING COIL NOT CENTERED AND CRIMPED AT THE CONNECTION PINProductionqualityshowshereaswell:onlythelatestproductionmachinescanaccuratelycenterandcrimptheconnectionpin.Dubiousmanufacturersmanagebysimplypushfittingtheheatingcoilontotheconnectionpin.However,therequiredprotectionagainstshort-circuitingcannotbeguaranteedinthismanner.(Forthis,pleaseseeFigures5and13)
DEFECTIVE CONTACTInlowqualityglowplugs,thepositionoftheelectricalconnectionlugsdoesnotcomplywiththeOEspecifications.Eventhoughtheconnectionlookssimilartothatoftheoriginalglowplugs,thecontactwillnotbecompletedcorrectly.Theelectricalconnectiontotheglowplugisthusnotguaranteed.Someofthesemanufacturersalsosaveonthematerialfortheconnectingcom-ponents–atthecostoftheelectricalcontact.(SeeFigure16)
GLOW TUBE NOT ACCURATELY WELDEDManycheapmanufacturersdonothavetheproductiontechnologytoaccuratelyweldaglowtube.Theresult:Hairlinecracksintheglowtubes–andthusleaks,whichagaincouldresultinshort-circuits.
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17
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4/5
5/6
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Symptom Risk
11 Glowtubetiptwistedoff, Scaledeposits,reducedservicelife heatingrodtoothin
12 Glowspiralnotproperlydesigned Batteryoverloaddueto excessivecurrentconsumption, consequentlyriskofburning oftheglowtimecontrolunit contacts:Thisreducestheservice lifeorimpairsthefunction
5/13Glowcoilmountedininclined Shortcircuit position
14 Conedoesnotcorrectfitfor Sealingproblems,destruction thecylinderhead ofthecylinderhead
15 Surfacewithoutsurfacecoating Seizinginthebore
16 Sleeveisonlypushed Looseningandinterruption ofcurrentsupply,loosecontact
17 Pencillengthnotaccordingto Ifpencillengthistoolong: manufacturer‘sspecifications glowplugisdestroyedbythe injectionjet.Ifitistooshort: startproblems
Symptom Risk
1 Singlesealing Notwaterproof
2/9 Fillingtheglowtubewith Badinsulation,swellingoftheLow grademagnesiumpowder glowtube
3 2-coiltechnologyrequired, Profileofcharacteristicsdoes butonlyonecoilinstalled notcomplywiththemanufacturer’s specification
4 Wallthicknessnotcontinuous Glowplugblows
5 Coilinaninclinedpositioninthe Shortcircuit glowtube
6 Glowtubenotcentered,thusno Theglowplugisdestroyed concentricity:Theglowplugisinan bytheinjectionjetandburns inclinedpositionintheantechamber orturbulencechamber
7 Heatingrodwithhairlinecracks Blowing
8/9 Heatingrodtipisfilledwithnot Shortcircuit,inflationofthe compressedand/ormoist glowrod,reducedservicelife magnesiumpowder
10 Roundenddrilledon,notcorrectly Blowing weldedthrough
How to recognize low-quality glow plugs
Cheap designs - something you should do without
Causes of failure in pencil type glow plugs
Inwarmanddryweather,adieselenginewillstartevenifoneglowplugisdefectiveandonlytheotherplugspreheat.Insuchanevent,therewillusuallybeincreasedpollutantemissionandpossiblyalsoknockingduringstart,however,thedriverwillnotconsciouslynoticethesesigns,orwillnotknowhowtointer-pretthem.Therewillbeaunpleasantsurpriseoncetheweatherbecomescoldandclammy,andthefirstnightfrostsetsin:the„heatingcontribution“tothedieselenginefailstofunction,andtheenginewillatbeststartwithdifficultlyandproducesmoke–mostprobably,however,nothingwillworkatall.Belowisalistoftypicaldamageandtherelatedcauses.Inmostcases,itwillbepossibletocorrectafaultusingthisdiagnosticsaid.
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Causes:Coilinterruptionduetoa) operationattoohighvoltage,e.g. jumpstartb) toolongpowersupplyduetoa stuckrelayc) impermissiblepost-heatingwhen engineisrunningd) useofanonpost-heatingglowplug
Causes:Overheatingoftheheatingrodduetoa) beginningofatomizationtooearlyb) cokedorwornnozzlesc) enginefailure,e.g.becauseofpiston jamming,valvebreakage,etc.d) drippingnozzlese) seizedpistonring
Causes:Overheatingoftheheatingrodduetoa) Atomizationbeginstooearly,and heatingrodandheatingcoilare overheatedduringthis;theheating coilbecomesbrittleandbreaks.b) closedannulargapbetweenplug housingandheatingrod;asa consequence,toomuchheatis deflectedfromtheheatingrod, theregulating
Causes:a) Tornoffconnectingbolt:Thecurrent connectingnutwastightened withexcessivetorque.b)Damagedhexagon:Useofincorrect tool;theplugisdeformedand causesashortcircuitfromthe housingtotheroundnut.
Corrective action:a) Jumpstartonlyatthevoltageoft heon-boardpowersupply.b)/c)Checkpreheatingsystem,replace glowtimerelay.d) Installpost-heatingglowplugs.
Corrective action:a) Setinjectiontimingpointaccurately.b) Cleanorreplaceinjectionnozzlesc) Checkfueljetprofile.d) Overhaulorreplaceinjectionnozzlee)Ensurepistonringscanmovefreely
Corrective action:a) Checkinjectionsystem,setinjection pointaccurately.b) Whenscrewinginaglowplug, alwayscomplywiththetightening torquespecifiedbythevehicle manufacturer.
Corrective action:a) Tightencurrentconnectingnutwith torquewrench.Alwaysobserve specifiedtighteningtorque.Donot lubricateorgreasethethread.b) Tightenplugwithsuitabletorque socketwrench.Strictlycomplywith thespecifiedtorque(refertospeci- ficationsofthecarmanufacturers). Donotoilorgreasethethread
HEATING ROD WITH FOLDS AND DENTS
HEATING ROD PARTIALLY OR FULLY MOLTEN OR BROKEN OFF
HEATING ROD TIP DAMAGED
CONNECTING BOLT TORN OFF, HExAGON DAMAGED
Glow plug test device: Testing without removing the plugs
How to start a diesel engine quickly and reliably
Now,withthenewBERUglowplugtester,youcanteststeelandceramicglowplugsonvehicleswith12volton-boardvoltage,easily,quickly,andreliably-individually,andwithnoneedtodismantlethemorstarttheengine.
ThenewBERUglowplugquicktesteroffersmanyadvantagesforpracticeintheworkshop:nReliable,fastandeconomicaltesting,becauseitisnot necessarytoremovetheplugsorstarttheenginenItisnotnecessarytopre-selecttheglowplugtype (steelorceramics)nAutomaticreconitionoftheglowplugvoltagerating (from3.3–15volts)nTestingundertheactualconditionsnEasytooperatenPossibilityfortestingeachindividualglowplugnAnaloguedisplayforheatingandcurrentregulation (possibilityforcomparingindividualglowplugsforcurrent consumptionandregulationperformance)nProtectionagainstshortcircuitsandpolarityerrorsnProtectionagainstoverload (monitoringofglowpluginadditionviaindependentcircuit)nTestprocedurecontrolledbycharacteristicscurvesasin electronicscontrolequipment.nDetectionofloosecontactsbyprocessor,thenasecondcheck.nSpecialmicrocontrollersoftwareintegratedintothetester
There should be a BERU glow plug test device in every workshop.
Our tip:Check the glow plugs with the BERU glow plug quick tester. Ideally, you should replace the entire glow plug set in the event of any defects or impaired function.
Experience shows that glow plugs mostly reach their wear limit shortly after one another – and once the connector leads and the conductor rails have been removed, it is cheaper to change the whole set than to have to replace further plugs only a short time later.
The problem
Fumeduringstart,Smokeproduction
Knockingduringstartphase
Battery-depletinglongstartphase
Difficultandirregularrunningofengine
Engineonlystartsrunningafterseveralstartingattempts
Engineonlystartsrunningwithpro-ductionofunpleasantsmells
Theglowrodisslightlymoltenorscaled
Theglowrodisentirelymelted
The cause
Glowplugwithonlyonecoil,toolowtemperature
Glowplugwithoutlimitingeffectandwithoutheatreserve
Glowplugonlyheatsupslowly,heat-uptimetoolong
Endtemperatureofglowplugtoolow
Glowplugdefective
Theelectricalvaluesoftheglowplugshavenotbeensetappropriately
Thewallthicknessoftheheatingrodistoosmall(thisisoftenthecasewithcheapglowplugs)
Theinjectionnozzleisdefective
BERU‘s solution
UseBERU2-coiltechnologyglowplug(heatingandregulatingcoilensurethatahighertemperatureisreachedduringashorterheat-uptime)
InstallBERUpost-heatingglowplugsforabetterandquickerheatsupply
InstallBERUGNglowplugthathasaccuratelybeenadaptedtotheengineandthe3-phaseglowsystem(pre-heating–startheating–post-heating)
ReplacenozzleholderwithBERUreplacementnozzleholderassembly
Workshop tips
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Glow plug Tighteningthread torque
M8 20Nm M9 22Nm M10 35Nm M12 45Nm
Glow plug Tighteningthread torque
M8 10NmM9 12NmM10 15NmM12 22Nm
Connecting nut Tighteningthread torque
M4 2NmM5 3Nm
Workshop tips
TIGHTENING TORQUEObservetighteningtorquewhendisassemblingglowplugs.
WHAT MUST I DO WHEN THE TIGHTENING TORQUE HAS BEEN REACHED?Undernocircumstancesshouldyoucontinueturning–theglowplugmightotherwisebreakoff.Instead,proceedaccordingtothe3-pointprogram:„Slightlyloosen–Warmup–Unscrew“:
1.Slightlyloosen:Applyagenerousamountofsyntheticoilto theglowplugthreadandleavetoact,ifpossibleovernight, orlonger.2.Warmingup:Runengineuntilitiswarmoruseaseparate cabletosupplycurrenttothefunctionalglowplugsfor 4-5minutes(onlypossibleforglowplugswith11–12V operatingvoltage)-theglowplugwillheatupandburnloose.
3.Unscrew:Thentrytounscrewitonceagainandcarefully loosentheglowplugoutofthecylinderheadwithasuitable tool.(Donotexceedthemaximumlooseningtorque–see tableabove.Alwaysstopbeforereachingthetightening torque,ifnecessarytryonceagainbyheatingup.)
Aftertheoldglowplugshavebeenremoved,alwayscleanthethread,theconicalseatandtheglowplugchannelinthecylinderheadwithsuitabletools.(seebelow).
TIGHTENING TORQUEWhenscrewinginnewglowplugs,thetighteningtorquestatedbythevehiclemanufacturermustbeobserved.
Note:Thetighteningtorqueoftheconnectingnutmustalsobeobservedforglowplugswithscrewedconnection.Inparticularafterbaking(coking)betweentheglowrodandthecylinderhead,thecylinderheadboreisoftensoiledbyresiduesfromburningordirtparticles.Suchcokingcaneasilyandsafelyberemovedfromcylinderheadswith10-mmthreads–withtheBERUreamer(RA003-0890100003).
AND THIS IS HOW IT’S DONE:nProvisionallycleantheglowplugborewithacloth.nApplygreasetocuttingareaofBERUreamerandscrewit inthecylinderhead:Thecombustionresidueswillstickto thegreaseandwillberemovedwhenunscrewingthetool.nThenewglowplugcanthenbemountedwithoutany problem(pleaseobservetighteningtorqueagain!).nBeforeinstallingtheglowplugs,greasetheshaftand threadareaswithGKgrease(GFK01–0890300034)
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Now inject synthetic oil here.
These combustion residues can be removed with the BERU reamer.
The BERU reamer – (RA003 – 0 890 100 003) loosens coking that might occur after „baking-on„ between glow plug and cylinder head.
ONLY remove and fit glow plugs using a torque wrench.
Important when replacing glow plugs: Keep to the torques!
Torques
BERU reamer: for a quick and reliable cleaning of the cylinder head bore
GKF01 - 0 890 300 034
®
Perfectionbuilt in
Global Aftermarket EMEAPrins Boudewijnlaan 52550 Kontich • Belgium
www.federalmogul.comwww.beru.federalmogul.com
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