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1 Introduction　　　　　　　　　　　　　　　

Globalvehiclesalesfellheavilyduetotheglobalfinan-cialcrisisthatstartedintheU.S.in2008,beforestartingtoincreaseagainin2009andovercomingthecreditcri-sis inEuropein2010.Salesin2014reachedanall-timehigh,buoyedbyrobustgrowthinChinaandlow-interestratesandlowcrudeoilpricesintheU.S.thatcreatedfa-vorablemarketconditions.At the same time, awareness of the environment

andenvironmentally friendly technology isgrowingallaround theworld, leading to the introductionofmorestringent fueleconomyandemissionsregulations inJa-pan,theU.S.,andEurope.Atthesametime,whileotherregionshavedecidedtoadopttheemissionsregulationsdrawnupbyEuropeortheU.S.,morecountriesarein-troducingindependentregulations,suchasthoseinChi-naandIndia.Asaresultofthesetrends,technologiestolowerengineemissionsorboostfuelefficiencyaregrow-inginsophistication,affectingforvehiclesthatautomak-ersarelaunchingonaglobalbasisaswellasvehiclesforemergingmarkets.This article introduces themain gasoline engines

andnewengine technologies thatweredevelopedandlaunchedbetweenJanuaryandDecember2014. Italsosummarizesthetrendsintheresearchanddevelopmentofgasolineengines.

2 Japan　　　　　　　　　　　　　　　　　　　

2. 1. SummaryTheJapanesevehiclemarketsufferedadoubleblow,

fromtheU.S.financialcrisisin2008andtheGreatEastJapanEarthquakein2011.Themarkethassincerecov-eredfromthesesubstantialdropsinsalesandrecordedayear-on-year increase in2014,partlydue to the last-minute demand that occurred before the consump-tiontaxhike inApril1014. Inparticular,salesofmini-vehiclesgrew,reflectingtheexcellentfueleconomyand

lowmaintenancecostsofthesevehicles.Salesofhybridvehicleswerealsorobust.Mostof thenewvehicles launched in2014wereeli-

gibleunderJapan＇spreferentialtaxschemeforenviron-mentallyfriendlyvehicles.Thefiercecompetitioninthemini-vehiclemarket forbetter fuelefficiencycontinued,andanumberofvehicleslaunchedin2014havealreadyexceededthe fueleconomystandards for2020bymorethan20%. Anumberofnewmini-vehiclesandhybridvehiclesthatuseregenerativeenergytoprovidemotorassist onaccelerationwere launched. Othervehiclesachievedbetterfueleconomybyrefiningandcombiningexistingtechnologieswithouttheuseofmotorsorotherelectricaldevices, suchashighcompressionratiosandimprovedcombustioncharacteristics,higherenginether-malefficiencybyreducing losses, lighterbody frames,andcoordinatedcontrolwith the transmission,andthelike.Anumberofvehiclesinstalledwithdownsizedtur-bochargedengineswerealsolaunched.2. 2. Trends of each manufacturerTable1showsalistofthemainnewtypesofgasoline

enginesthatweresoldbyJapaneseautomakersin2014.Asummaryofthenewenginesdevelopedbyeachman-ufacturerisprovidedbelow.2. 2. 1. DaihatsuTheDaihatsuMirae:Sisinstalledwiththeinline3-cyl-

inder0.66-literKFengine(Fig.1).Thisengineimprovesfuelefficiencythroughahighercompressionratio thanthepreviousengine (11.3 increasedto12.2), re-designedintakeportgeometrytointensifytumble,andhighigni-tionperformance sparkplugs that expand the rangeof the flame in the initial stageof ignition. Knocking,whichtendstooccurathighercompressionratioswaspreventedbyadoptingtheAtkinsoncycle,dualinjectors(Fig.2),andcooledexhaustgasrecirculation(EGR).TheAtkinsoncyclealsoreducespumping lossandthedualinjectorsstabilizecombustionbyatomizingthe injectedfuel into extremely small droplets. Combining these

Gasoline Engines


measureswithlowerrunningresistanceandgreaterre-generationofdecelerationenergythroughanenhancedpowergenerationcontrolenablesthisvehicletoachieveafuelconsumptionof35.2km/lintheJC08testcycle.2. 2. 2. Fuji Heavy IndustriesThenewSubaruLevorgisinstalledwiththehorizon-

tallyopposed4-cylinder (“flat4”)1.6-literFB16directinjectionturbo (DIT)engine (Fig.3). Combiningdirectinjectionwithaturbochargergivesthisengineequalor

higherpowerthana2.5-liternaturallyaspiratedengine.Comparedtothepreviousunit, thisengine features im-provedcylinderheadinternalcoolingperformance,multi-stagefuelinjection,improvedcombustioncharacteristicsthroughahigh-tumblecombustionchamber,andalargerEGRcooler. Asaresultof thesemeasures, thisengineachievesacompressionratioof11.0withregulargasolineandfuelconsumptionof17.4km/lintheJC08testcycle.ThenewLegacyfeaturestheflat42.5-literFB25en-

Table 1 Main new gasoline engines in Japan

Manufacturers EnginemodelCylinderarrangement

Bore×stroke(mm)

Displacement(L)

Compressionratio Valvetrain

Maximumpower(kW/rpm)

Maximumtorque(Nm/rpm)

Maininstallationvehicles

Characteristics

Daihatsu KF Inline3

63.0×70.4 0.658 12.2 DOHC4 V 36/6 800 57/5 200 Mirae:S Variable intake valve timing,sparkplugswithhigh ignitionperformance,Atkinson cycle,dualinjectors,cooledEGR

FujiHeavyIndustries

FB16DIT Flat4turbocharged

78.8×82.0 1.599 11.0 DOHC4 V 125/4 800─5 600

250/1 800─4 800

Levorg Directinjection,variableintake/exhaust valve timing, cooledEGR, tumblegeneratingvalves,waterjacketspacer

FB25 Flat4 94.0×90 2.498 10.3 DOHC4 V 129/5 800 235/4 000 Legacy,Outback

Variable intake/exhaust valvetiming

Mazda P3-VPS Inline4

71.0×82.0 1.298 12.0 DOHC4 V 68/6 000 121/4 000 Demio Direct injection,variable intakevalvetiming,Millercycle

Nissan MR16DDT Inline4turbocharged

79.7×81.1 1.618 10.5 DOHC4 V 140/5 600 240/1 600─5 200

Juke Directinjection,variableintake/exhaustvalve timingwithmid-position lock,Millercycle, low-pressure cooledEGR, polishedbore thermal spray cylinderblock, electronic wastegate,variablecapacityoilpump

Suzuki R06A Inline3

64.0×68.2 0.658 11.5 DOHC4 V 38/6 500 63/4 000 Alto Variable intake/exhaust valvet iming, EGR, cyl inder headintegratedwith the exhaustmanifold

R06A Inline3

64.0×68.2 0.658 11.2 DOHC4 V 38/6 000 63/4 000 WagonR Variable intake/exhaust valvetiming

Toyota 1KR-FE Inline3

71.0×83.9 0.996 11.5 DOHC4 V 51/6 000 92/4 400 Passo,Vitz

Atkinson cycle, cooled EGR,variable intake valve timing,cylinder head integratedwiththe exhaustmanifold, waterjacketspacer

1NR-FKE Inline4

72.5×80.5 1.329 13.5 DOHC4 V 73/6 000 121/4 400 Vitz,Ractis

Atkinson cycle, cooled EGR,variable intake/exhaust valvetiming (intake side: electronic),water jacket spacer , 4 -2 -1exhaustmanifold

8AR-FTS Inline4turbocharged

86.0×86.0 1.998 10.0 DOHC4 V 175/4 800─5 600

350/1 650─4 000

NX200 t Atkinsoncycle,direct injection+ intake port injection, twin-scrollturbocharger,water-cooledintercooler, cylinderheadwithintegrated 4 into 2 exhaustmanifold,variablevalve timingwithmid-position lock, sodium-filledexhaustvalves


gine(Fig.4).Inadditiontosubstantialenhancementstotheintake,exhaust,andcombustionsystems,thisengineimprovesfuelefficiencybycreatingmoreintenseintaketumbleandadoptingahighercompressionratio.2. 2. 3. MazdaThenewMazdaDemio is installedwith the inline

4-cylinder1.3-literPS-VPSengine (Fig.5). Thisenginefeaturesadifferentcompression ratio to thepreviousSKYACTIV-Gfamilyengines,enablinghighertorque inallenginespeedregions,aswellasbetteracceleration

andfuelefficiency.2. 2. 4. NissanTheNissanJukeisinstalledwiththeinline4-cylinder

1.6-liter turbochargedMR16DDTengine (Fig.6). Thisengine features innovationssuchasahighercompres-sionratio (increasedfrom9.5 to10.5) thanthepreviousengine, apolishedbore thermal spraycylinderblock,redesignedintakeportandpistontopsurfacegeometry,aturbochargerwithalowerrotormomentofinertia,andanexhaustmanifoldintegratedwiththeturbinehousing.

Fig. 1 Daihatsu 0.66-liter KF engine （4）

Fig. 2 Daihatsu dual injectors（4）

Dual injector

Fig. 3 Fuji Heavy Industries 1.6-liter FB16 DIT engine（4）

Fig. 4 Fuji Heavy Industries 2.5-liter FB25 DIT engine（4）

Fig. 5 Mazda 1.3-liter P3-VPS engine（4）

Fig. 6 Nissan 1.6-liter MR16DDT engine（4）


Theseenhancementshavetheeffectof improvingbothaccelerationandfuelefficiency.Inaddition,low-pressurecooledEGRis introducedupstreamoftheturbochargercompressorafter theexhaustgas fromthecatalyst iscooled, thereby improving fuelefficiency in the turbo-chargeroperationrangebyreducingknockingandtheexhaustgastemperature.2. 2. 5. Suzuki Motor CorporationThenewSuzukiAltoisinstalledwiththeinline3-cyl-

inder0.66-literR06Aengine (Fig. 7). Thisengine im-provesfuelefficiencybyincreasingthecompressionratio(from10.5to11.5),adoptingvariablevalvetimingontheexhaustsideaswellastheintakeside,installinganEGRsystem, and redesigning the intakeandexhaustportgeometry.Inaddition,thesizeandweightoftheenginewerereducedbyadoptingacylinderhead integratedwith theexhaustmanifoldandasimplercatalystcasestructure.Combinedwithalighterbody,high-efficiencycontinuouslyvariabletransmission(CVT),andlowerrun-ningresistance,thisengineachievesafuelconsumptionof37.0km/lintheJC08testcycle.TheWagonR isalso installedwiththe inline3-cylin-

der0.66-literR06Aengine. Theengine in thisvehiclefeaturesrefinementsto increasethermalefficiencysuchas ahigher compression ratio, improved combustioncharacteristics,andlowerfrictionloss.Itcombinesthesewithageneratorwithamotor function (ISG),which ispoweredbyregenerateddecelerationenergy toassistacceleration, therebyachievingfuelconsumptionof32.4km/lintheJC08testcycle.Thebelt-drivenISGstarterfunctionalsoreducesnoiseonenginere-startwhentheidlingstopsystemisoperating.2. 2. 6. ToyotaTheinline3-cylinder1.0-liter1KR-FEengine(Fig.8)in-

stalledinvehiclessuchastheToyotaPassoandToyotaVitzadopts theAtkinsoncycleandcooledEGRprevi-ouslyadoptedinhybridvehicleenginestoreducepump-ingloss.Thisenginealsousesawaterjacketspacertooptimizethecylinderwall temperatureandreduceme-chanicalloss.Duetoacombinationofotherrefinements,suchasredesignedintakeportandcombustionchambergeometry to intensify tumbleandachievehigh-speedcombustion,aswellasahighercompressionratio, thisengineachievesamaximumthermalefficiencyof37%.Asaresult,thePassoachievesfuelconsumptionof27.6km/lintheJC08testcycle.Theinline4-cylinder1.3-liter1NR-FKEengine(Fig.9)

installedintheVitz,Ractis,andthelikealsoadoptstheAtkinsoncycleandhighcompressionratio (13.5) fromhybridvehicleengines. Italso featureselectroniccon-tinuouslyvariablevalve timingon theexhaustside toimprovecoldstartcapabilityand fuelefficiency in lowloadengineoperation regions. Combining thesemea-

Fig. 7 Suzuki 0.66-liter R06A engine （4）

Fig. 8 Toyota 1.0-liter 1KR-FE engine（4）

Fig. 9 Toyota 1.3-liter 1NR-FKE engine（4）


sureswithcooledEGRandhigh-tumbleintakeports,theresultinghigh-speedcombustionexpandsboththeEGRandknocking limits. Finally,resin-coatedbearingsandothertechnologiestoreducefrictionlossgivethisengineamaximumthermalefficiencyof38%.ThenewLexusNX200t is installedwith the inline

4-cylinder2.0-liter turbocharged8AR-FTSengine (Fig.10).Thisenginecombinesacylinderheadwithaninte-grated4into2exhaustmanifoldwithatwin-scrollturbo-chargertoimprovelowendtorqueandoptimizetheex-hausttemperature.Inaddition,thecombinationofdirectinjection,injectionintotheintakeports,andhigh-tumble,enablehigh-speedcombustion.Theenginealsofeaturesbetterresponsethroughawater-cooled intercoolerthatisattacheddirectly to theengine,better fuelefficiencyin lowengineloadoperationregionsandcoldstartper-formancethroughtheuseofcontinuouslyvariablevalve

timingwith amid-position lock system, andvarioustechnologies to reduce friction loss suchasavariablecapacityoilpumpandtheadoptionofsurfacetreatmentonthepistonskirts.Theresultisimprovementsinbothpowerandfuelefficiency.

3 U.S.　　　　　　　　　　　　　　　　　　　　

3. 1. SummaryTheU.S. economywas robust in 2014, spurring a

continuing increase invehiclesalesdueto low interestratesandfallinggasolineprices.Themarketessentiallyrecoveredtopre-financialcrisislevels.Salesofsmallandmediumsizedvehicleswereparticularlystrong.As theU.S.phases inmore stringent fuel economy

regulationsover thenext fewyears,2014sawvariousinnovationstoimprovefuelefficiency,suchasdownsizedturbochargeddirectinjectionenginesandcylinderdeac-tivationinlargerdisplacementengines.3. 2. Trends of each manufacturerTable2showsa listof themainnewtypesofgaso-

lineenginesthatweresoldbyU.S.-basedautomakersin2014.Asummaryofthenewenginesdevelopedbyeachmanufacturerisprovidedbelow.3. 2. 1. ChryslerThehigh-performanceV86.2-literHemiengine (Fig.

11) installed in theDodgeChallengerandCharger fea-turesvarious technologies to improve fuel efficiency,suchasasupercharger,water-cooledintercooler,sodium-filledexhaustvalves,andvariablecapacityelectricwaterpump. Theenginehasamaximumpowerof527kWandamaximumtorqueof881Nm.

Table 2 Main new gasoline engines in the U.S.


Bore×stroke(mm)

Displacement(L)





Characteristics

Chrysler 6.2 LHEMI V8supercharged

103.9×90.9 6.166 9.5 OHV2 V 527/6 000 881/4 000 Challenger,Charger

Supercharger , water-cooledintercooler,sodium-filledexhaustvalves, powdermetal forgedc onnec t i ng r od s , v a r i ab l ecapacityelectricwaterpump

Ford 2.3 LEcoBoost

Inline4turbocharged

87.5×94.0 2.260 9.5 DOHC4 V 231/5 500 434/3 000 Mustang D i r e c t i n j e c t i o n , tw i n - s c r o l lturbocharger, variable intake/exhaustvalvetiming,cylinderheadintegratedwiththeexhaustmanifold

2.7 LEcoBoost

V6twinturbocharger

83.0×83.0 2.699 10.0 DOHC4 V 242/5 750 509/3 000 F150 Directinjection,twin-turbocharger,variable intake/exhaust valvetiming, cylinderhead integratedwiththeexhaustmanifold

GM LT1 V8 103.2×92.0 6.162 11.5 OHV2 V 339/6 000 624/4 600 Corvette Direct injection, OHV variable valvetiming,single-bankcylinderdeactivation,powdermetalforgedconnectingrods

Fig. 10 Lexus 2.0-liter 8AR-FTS engine（4）


3. 2. 2. FordFordaddedan inline4-cylinder2.3-literengine (Fig.

12)toitsglobalEcoBoostseries.IntheU.S.,thisengineis installed in theFordMustang. In thesamewayastheexistingmembersoftheEcoBoostseries,thisenginefeaturesbasicspecificationssuchasdirectinjection,con-tinuouslyvariableexhaustvalvetiming,andacylinderheadintegratedwiththeexhaustmanifold.Incombina-tionwithatwin-scrollturbocharger,thisengineachievespowerperformanceatleastequivalenttotheV63.7-liternaturalaspiratedengineused inthesamemodelof theMustang,withexcellentfuelefficiency.TheV62.7-literEcoBoostengineshowninFig.13was

installedintheF-150pick-uptruck.Inadditiontodirectinjection,continuouslyvariableexhaustvalvetiming,andacylinderhead integratedwith theexhaustmanifold,thisenginealsoincludesaplasticoilpan.Whileprovid-ingpowerat leastequivalent toaV63.5-liternaturalaspiratedengine, fuelefficiencywasalso improvedbytheadoptionofan idlingstopsystemanda lightweightaluminumbody.3. 2. 3. GMTheChevroletCorvette is installedwith the6.2-liter

LT1engine (Fig.14). Whileretainingthe90-degreeV82-overheadvalve(OHV)basiclayoutof itsfamoussmallblockpredecessor,thisenginealsofeaturestechnologiestoimprovefuelefficiencysuchasdirectinjection,ahighcompression ratio, continuouslyvariablevalve timing,andsingle-bankcylinderdeactivation. Thesemeasureshaveimprovedbothpowerandfuelefficiency.

4 Europe　　　　　　　　　　　　　　　　　　

4. 1. SummaryTheU.S.financialcrisis in2008andEuropeancredit

crisis in2010resulted incontinuedfalls invehiclesalesinEurope.However,salesfinallyroseonayear-on-yearbasisin2014forthefirsttimeinsevenyears.Althoughthemarketrecoveryisgradual,salesofvehiclesinstalledwithdownsizedengines to improve fuelefficiencyandreduceCO2continue toberobustandhaverisensub-stantially.Aparticulartrendin2014wasthelaunchofanumberof3-cylinderdownsized turbochargeddirectinjectionengines.4. 2. Trends of each manufacturerTable3showsalistofthemainnewtypesofgasoline

enginesthatweresoldbyEurope-basedautomakers in2014.Asummaryofthenewenginesdevelopedbyeachmanufacturerisprovidedbelow.4. 2. 1. BMWTheBMWi8plug-inhybridisinstalledwiththeinline

3-cylinder 1.5-liter turbochargedB38A15engine (Fig.15). Tunedtodifferentpowerlevels,thisengineisalsoinstalled in the218iActiveTourerandMini. PartofBMW＇sso-calledTwinPowerTurboseriesofengines, itfeaturesdirect injection,acontinuouslyvariablevalveliftmechanism, continuously variable exhaust valvetiming,andthermalspraybores. Thealuminumturbo

Fig. 11 Chrysler 6.2-liter Hemi engine（4）

Fig. 12 Ford 2.3-liter EcoBoost engine（4）

Fig. 13 Ford 2.7-liter EcoBoost engine（4）


housingiswater-cooledandintegratedwiththeexhaustmanifold, thereby improving fuelefficiencybyreducingweightandpromotingthewarm-upprocess.The4-cyl-inder2.0-literB48A20engine (Fig.16)usesatwin-scrollturbochargerthatachieveshigherefficiencybyrestrict-ingexhaustinterference.Thisengineisalsousedinthe2SeriesActiveTourerandMini.4. 2. 2. DaimlerTheMercedes-AMGGTisinstalledwiththeV84-liter

turbochargedM178engine (Fig. 17). Thisengine fea-turestwoturbochargersprovidedbetweentheVbanks(Fig.18),directinjectionwithpiezoinjectors,adrysumplubricationsystem,closeddeckcylinderblock,andtheNanoslidecylinder linercoating. Theresult isacom-pact lightweightenginewithhighpowerand low fuelconsumption,which iscapableofachieving650Nmortorquebetween1,750and4,750rpm.4. 2. 3. Opel

Table 3 Main new gasoline engines in Europe


Bore×stroke(mm)

Displacement(L)





Characteristics

BMW B38A15 Inline3turbocharged

82.0×94.6 1.499 11.0 DOHC4 V 170/5 800 320/3 700 I8 Direct injection,variable intake/exhaust valve timing, variablevalvelift100/4 400 220/1 250─

4 300218iActiveTourer,Mini

B48A20 Inline4turbocharged

82.0×94.6 1.998 10.2 DOHC4 V 170/5 000 350/1 250 225i,Mini Direct injection,variable intake/exhaust valve timing, variablevalvelift

Daimler M178 V8twinturbocharger

83.0×92.0 3.982 10.5 DOHC4 V 375/6 250 650/1 750─4 750

AMG-GT Direct injection,water-cooledinter coo ler , s tee l thermalspray cylinder core, dry sumplubrication,variablecapacityoilpump

Opel LE1 Inline3turbocharged

74.0×77.4 0.999 10.5 DOHC4 V 85/5 200 170/1 800─4 500

Adam Direct injection, variable intake/exhaust valve timing, cylinderheadintegratedwith theexhaustmanifold,variablecapacitywaterpump,powdermetal forgedconnectingrods,variablecapacityoilpump

PSA 1.2EB2 Inline3turbocharged

75.0×90.5 1.199 10.5 DOHC4 V 96/5 500 230/1 750 308，C3 Direct injection,variable intake/exhaust valve timing, sodium-filled exhaust valves, variablecapacity oil pump, timingbeltdrive

Volvo Drive-ET6

Inline4supercharger+turbocharger

82.0×93.2 1.969 10.3 DOHC4 V 225/5 700 400/2 100─4 800

S60，V60，XC60

Supercharger+ turbocharger,direct injection,variablecapacityoilpump,electricwaterpump

Fig. 14 GM 6.2-liter LT1 engine（4）Fig. 15 BMW 1.5-liter B38A15 engine（4）


TheOpelAdamis installedwiththe inline3-cylinder1.0-literturbochargedLE1engine(Fig.19).Thisisanewmemberof theEcotecengineseriesdevelopedbyGMandOpel.Itfeaturesdirectinjection,continuouslyvari-able intakeandexhaustvalve timings,acylinderheadwithan integratedexhaustmanifold,variablecapacityoilpump,oiljets,andothertechnologiestoimprovefuelefficiencyandpower,whilereducingnoise.4. 2. 4. PSA Peugeot CitroenThePeugeot308andCitroenC3areinstalledwiththe

inline3-cylinder1.2-liter turbochargedEB2engine (Fig.20).ThisisthelatestadditiontothePureTechengineseriesconsistingof1.0-literand1.2-liternaturallyaspi-

ratedengineswith intakeport injection. TheEB2fea-turesdirect injection,ahigh-speedturbo (270,000rpm),cylinderheadwithan integratedexhaustmanifold,andsodium-filledexhaustvalvesto increaseoutputandfuelefficiency.4. 2. 5. VolvoTheVolvoS60,V60,andXC60are installedwiththe

inline4-cylinder2.0-liter turbochargedT6engine (Fig.21), amemberof theDrive-Eengine series. TheT6shares thesameboreandstroke forbothgasolineanddieselvariants,achievingdifferentpowerlevelsthroughcombinationwithsupercharging. Themaximumpowerof theT6 is 225kW,which it achievesbycombiningdirect injectionwithbotha turbochargerandasuper-charger.

5 Trends in Research and Development

5. 1. Research system establishmentIn Japan, theResearchAssociation ofAutomotive

InternalCombustionEngineswasestablished in2014.

Fig. 16 BMW 2.0-liter B48A20 engine（4）

Fig. 17 Daimler 4-liter M178 engine（4）

Fig. 18 Daimler M178 turbocharger（4）

Fig. 19 Opel 1.0-liter LE1 engine（4）

Fig. 20 PSA 1.3-liter EB2 engine（4）


This isa framework forcooperativeresearchbetweenindustry,academia,andthegovernmenttoexaminesub-jectsrelatedtointernalcombustionengine(ICE)combus-tiontechnologiesandemissionstreatmentsystems. ItsestablishmentreinforcesICEresearchandshouldhelptopromotethedevelopmentofenginetechnology.5. 2. Downsized turbocharged enginesCenteredonEurope,downsizedturbochargedengines

arebecomingmorewidespreadasameansof improv-ing fueleconomythroughhighermechanicalefficiency.Researchintotheseenginesislookingforanexplanationfor thesuddenpre-ignitionphenomenonthatoccursatlowenginespeedhigh-loadregions,which isone issuepreventing improvements in torque. A largenumberof reportswerepublished in2014examining the rootcauses of thisphenomenon throughvisualizationandanalysis.5. 3. Homogenous charge combustion ignition (HCCI)

technologyHCCI isregardedasapromisingmeansofreducing

NOxandachievinghighlyefficientcombustionbyreduc-ingthecombustiontemperature.Forthisreason,ithasbeenthesubjectoflong-termresearchefforts.Current-ly,researchisexaminingissuesrelatedtopracticaladop-

tionsuchasexpandingtheactualusageregionsanden-suringtherobustnessofignitionandcombustion.Someresearchanddevelopmentisproceedingwithatargetedadoptionscheduleafewyearsinthefuture.5. 4. Thermal efficiency improvementThe latest report into improving thermal efficiency

includes achieving a thermal efficiency ofmore than45%bycombiningahighcompressionratioandmassiveEGRandoptimizingthebore/strokeratio(5).Itishopedthat thisresearchwillmovetowardpracticaladoption.Research is also continuing to examine exhaustheatrecoverybyhigh-responseheatshieldingorthermoelec-tricelementswith theaimof simultaneouslyreducingcooling lossandknocking. Oneparticular focus is thedivergencebetweenexpectedefficiencygainsandactualresults. Atthesametime,advances in instrumentationtechnologyarenot limitedtothevisualizationofsingle-cylinderengines.Reportshavealsodescribedamethodofdirectlyobservingthecombustionchamberofanac-tualengine,whichshouldhelptospeedupresearchanddevelopment.

References(1) Proceedings of the Spring andAutumnCon-

gressesof theSocietyofAutomotiveEngineersofJapan

(2) SocietyofAutomotiveEngineersofJapan,NewEngineDevelopmentsSymposium (symposiumNo.15-14)

(3) 23rdAachenColloquiumAutomobileandEngineTechnology,2014

(4) Websites,PRmaterials,andtechnicalreportsofeachcompany

(5) Tagishietal,Proceedingsof theSocietyofAu-tomotiveEngineersofJapanNo.121-14,pp.1-4,20145712

Fig. 21 Volvo 2-liter Drive-E T6 engine