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

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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.

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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

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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

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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)

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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

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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

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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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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

beru@federalmogul.com

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