RegistrulAutoRomân

Societatea pentruIngineria Automobilului

din România

IngineriaAutomobilului

S U P L I M E N T T R I M E S T R I A L G R A T U I T E D I T A T D E R E G I S T R U L A U T O R O M Â N

N R . 2 / F E B R U A R I E 2 0 0 7

SIAR ESTE AFILIATÃ LA

EUROPEANAUTOMOBILEENGINEERSCOOPERATION

INTERNATIONALFEDERATION OFAUTOMOTIVEENGINEERING SOCIETIES

Cutii de viteze avansate

- The actual development of humanity is based in it's major part on fossil resources con-sumption, among which oil is on top.The internal combustion engine, probably one of the most improved inventions ofmankind is nowadays in an almost paradoxical situation; it has an increased marketdemand but in the same time, it must accomplish more severe restrictions.A more powerful, more efficient, more reliable, less pollutant and continuouslycheaper engine is highly demanded, but seems to be quite an impossible thing.- Due to the hard competition in the field of the automotive industry very sophisti-cated equipments for experimental investigation are used in order to ensure fuelsavings and greenhouse gas emissions reductions. However behind many of therecent achievements there still is a classical investigation method, the pressure indi-cated diagram.- This work intends to offer the reader a general overview on this subject,together with a detailed image on what is the instrumentation, the demands andthe accuracy conditions necessary for sound results. It is mostly addressed to stu-dents, engineers and specialists from the internal combustion engines domain,but also to those who want to know more on this topic.The book is organized in three chapters, pressure indicated diagram sampling,calculation models related to the pressure diagram and analysis, prediction andoptimization techniques based on pressure diagram. It covers subjects as,piezoelectric pressure measurement system, thermodynamic, zero-dimension-

al and phenomenological models, cycle-by-cycle engine variability, and engine knockphenomena, rate of heat release influence on engine performance.

Cartea are la bazã cursuri susþinute la Universitatea Tehnicã din laºi. Ea se doreºte afi ºi un util material de studiu individual pentru specialiºtii angrenaþi direct în indus-tria automobilelor, pentru experþii ºi evaluatorii tehnici, ori pentru cei care lucreazãîn domenii conexe.O motivaþie majorã a editãrii volumului II constã în detalierea unor tehnologiirecente din industria autovehiculelor care vizeazã direct sau indirect siguranþa pasa-gerilor.În capitolul trei (primul capitol al prezentului volum), sunt prezentate principii ºisoluþii tehnologice ce permit disiparea unei energii importante din impact în struc-turi deformabile speciale, menþinând astfel în stare cât mai intactã cabina pasage-rilor. Tot în acest capitol sunt tratate pentru prima data în þarã în mod detaliat sis-temele pasive de securitate ce asigurã ºi protejeazã pasagerii pe durata produ-cerii coliziunilor, centurile de siguranþã, respectiv dispozitivele airbag.În capitolul patru este abordat sistematic subiectul limitelor biomecanice alecor-pului uman, insistându-se asupra indicilor de codificare a gravitãþii unortraumatisme, ca ºi pe definirea coridoarelor de siguranþã specifice diverselorpãrþi ale corpului afectate în impact. Tot aici sunt prezentate în detaliu familiide manechine fizice ºi virtuale utilizate în testãrile experimentale, respectivsimulãrile virtuale ale diverselor tipuri de coliziuni ºi a urmãrilor acestoraasupra pasagerilor.În capitolul cinci s-a analizat în detaliu influenþa personalitãþii, a comporta-mentului uman ºi a reacþiilor conducãtorilor auto asupra producerii acci-dentelor, prin prisma neadaptãrii la cerinþele traficului. Este analizatã îndetaliu corelaþia dintre unii indici accidentologici ºi anumiþi factori pertur-batori, printre care amintim consumul de alcool, de medicamente ºi dedroguri, starea de sãnãtate sau de obosealã; totodatã, au fost examinate ºierorile de conducere provenite din percepþia inexactã a realitãþii.Deosebit de util este ºi studiul privind managementul siguranþei rutiere prezentatîn al ºaselea capitol, tratarea problematicii abordate dupã metodele actuale utilizate în CE garan-tând succese similare, care sunt deja vizibile ºi în aplicaþiile recente din þara noastrã.Capitolul ºapte este dedicat unei noi discipline, accidentologia rutierã, apãrutã ºi dezvoltatã în lume în ultimii35 ani, dar ale cãrei influenþe în reducerea numãrului ºi gravitãþii accidentelor rutiere s-au fãcut simþite. Seoferã accesul la metodologiile moderne, economice, sigure ºi eficiente, de reducere a numãrului ºi gravitãþiiaccidentelor, a cãror aplicare poate diminua rapid decalajele þãrii noastre faþã de statele CE în ceea ce priveºtesiguranþa circulaþiei.Ultimul capitol analizeazã rolul infrastructurii ºi logisticii rutiere asupra siguranþei traficului; materialul pre-zintã interes prin expunerea sinteticã a normativelor ce trebuie respectate la construcþia ºi întreþinerea dru-murilor ºi podurilor, la semnalizarea ºi dirijarea intersecþiilor, la iluminarea ºi vizibilitalea obstacolelor.

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Founded in 1990, theSociety of Automo-tive Engineers from

Romania has as strategicobjective the stimulationof national and internatio-nal cooperation of auto-motive engineers throughRIA (the AutomotiveEngineers Review). To-day through the reviewAutomotive Engineering,

SIAR wishes to promote the results of different stu-dies, research and original projects of RomanianEngineers.SIAR applid different programs like:- The affiliation at International Federation ofAutomotive Engineers Societies and (EuropeanAutomobile Engineering's Cooperation and the orga-nization in Brasov of two FISITA Council reunions;- The establishing of partnerships with the membersocieties of FISITA. A main point in this activity wasthe partnership with SAE International (USA),established in 1996;- The stimulation of engineers, specialists, researchers,students to participate with papers at InternationalsCongresses;- The including of SIAR Congresses at Brasov(CONAT), Bucharest (ESFA), Pitesti (CAR), Craiova(SMAT), Cluj-Napoca (AMMA) and Timisoara(MVT) under the patronage of FISITA - EAEC;- The organization of seminaries, conferences and pro-fessional reunions for specialists in transportation,automobiles, road telemathics, vehicles accident recon-struction, quality, material science, electronics andcomputer science, development, diagnosis, liability;The cooperation with the Auto Test review willimprove the professionalism, scientific level and distri-bution area and will promote the quality of thestudies, research and projects of our automotiveschool.

Prof. Dr. Eng. (Ph.D.) Anghel CHIRUDean, University of Braºov

Principiul liberei cir-culaþii a bunurilorsemnificã, în cazul

vehiculelor rutiere, faptulcã un anumit vehicul dejaomologat comunitar detip pe baza unei directivecadru, aºadar cel pentrucare s-a demonstratîndeplinirea cerinþelortehnice impuse, nu mainecesitã reomologare laintroducerea lui în România. Procedura aplicabilã laachiziþionarea unui vehicul din România trebuie sa fieabsolut aceeaºi cu cea aplicabilã în cazul în carevehiculul ar fi cumpãrat din oricare alt stat membruUE.ªi, cel puþin în ceea ce priveºte atribuþiile RAR, vãasigurãm de respectarea deplinã a celor de mai sus.Ca o consecinþã directã, apare ca element de noutaterenunþarea la impunerea criteriului de poluare laprima înmatriculare în România a vehiculelor uti-lizate (vestitele norme Euro 3), dar numai pentruvehiculele care au fost ultima datã înmatriculate într-un stat membru UE. Celelalte vehicule (ca incidenþãse remarcã cele din Statele Unite ºi Canada) trebuieîn continuare sã respecte normele de poluareeuropene Euro 3.În concluzie, aderarea României la UE aduce otratare preferenþialã pentru vehiculele din UE dinpunct de vedere al simplificãrii procedurilor RAR(tarife mai mici ºi timpi de rãspuns de asemenea maibuni), în timp ce pentru vehiculele care provin dinafara UE nu se modificã modul de lucru care se apli-ca ºi pânã acum.Fãrã a comenta dezbaterile generate de aplicarea taxeispeciale pentru prima înmatriculare în România ºi maiales rezultatul lor final, sperãm ca mentalitatea noastrãsã nu compromitã eforturile care dureazã de 15 ani ºiprin care, deocamdatã, am reuºit sã nu devenim ultimadestinaþie a vehiculelor uzate ale Europei.

ªef Departament Omologãri IndividualeCristian BUCUR

Privilegii pentru vehiculele din UE

PromotingProfessionalism

4 Ingineria Automobilului Nr.2

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Prof. Dennis Assanis, University of Michigan

United States of America.

Prof. Bert BreuerTechnical University of Darmstadt,

Germany

Prof. Nicolae BurneteTechnical University of Cluj-Napoca Romania

Dr. Felice E. CorcioneEngines Institute, Naples, Italy

Prof. Cedomir DubokaUniversity of Belgrade,

Belgrade, Serbia

Prof. Pedro EstebanInstitute for Applied Automotive

Research, Tarragona, Spain

Prof. Radu GaiginschiTechnical University „Gh. Asachi“ of

Iaºi, Romania

Dr. Uwe GeigerVizepresident

Development EngineSistems INA-Schaeffler KG,

Herzogenaurach, Germany

Eng. Eduard Golovatai-SchmidtINA-Schaeffler KG, Herzogenaurach,

Germany

Prof. Berthold GrunwaldTechnical University of Darmstadt,

Germany

Prof. Alexandre HerleaUniversite de Technologie de Belfort-Montbeliard, France

Prof. Peter KucharUniversity for Applied Sciences,Konstanz, Germany

Prof. Nicolae V. OrlandeaAssociate Editor at Journal of Multi-body Dynamics, London,United Kingdom

Prof. Andreas SeeligerInstitute of Mining and MetallurgicalMachine, Engineering, Aachen Germany

Prof. Cornel StanWest Saxon University of Zwickau, Germany

Prof. Ulrich SpicherKalrsuhe University, Karlsruhe,Germany

Prof. Ion TabacuUniversity of Piteºti, Romania

Prof. Dinu TarazaWayne State University, United Statesof America

SCIENTIFIC BOARD - LISTA PERSONALITÃÞILOR

Serie nouã a Revistei Inginerilor de Automobile din România (RIA), 1992-2000Cod ISSN 1842 - 4074

Director generalDaniel PATENTAªU

Director tehnicClaudiu MIJA

Editor CoordonatorLorena STROE

RedactoriRadu BUHÃNIÞÃ

Emilia VELCU

Contact:Calea Griviþei 391 A,

sector 1, cod poºtal 010719, Bucureºti, România

Tel/Fax: 021/202.70.17E-mail: autotest@rarom.ro

Contact:Facultatea de Transporturi,Universitatea Politehnica

Bucureºti, Splaiul Independenþei 313,

sala JC 005, Cod Poºtal 060032, Sector 6

Bucureºti, România Telefon/Fax: 021/316.96.08

E-mail: siar@siar.ro

Tipar

Reproducerea integralã sauparþialã a textelor ºi imaginilor se

poate face numai cu acordulRevistei Auto Test, a Registrului

Auto Român ºi a Societãþii pentruIngineria Automobilului din

România

Chairman: Prof. Eugen Miahai NEGRUª - President of SIAR, Romania

Vice-chairman: Prof. Cristian ANDREESCU „Politehnica“ University of Bucharest

Vice-chairman: Prof. Anghel CHIRU „Transilvania“ University of Braºov, Romania

Scientific Secretary: Dr. Cornel VLADU Secretary General of SIAR, Romania

Registrul AutoRomân

Auto Test

SIAR

G. CANALE & C. SRL

REZUMATLucrarea prezintã o posibilitate interesantã defolosire a amestecurilor sãrace în motoarele cuaprindere prin scânteie prin transformarea unuipropulsor clasic cu ardere internã, apelând lasoluþii tehnice complexe. Beneficiul principal alsoluþiei de stratificare a amestecului bazatã peinjecþia directã de combustibil într-o camerã deardere divizatã, fiind obþinerea unui consumredus de combustibil în condiþiile unui nivel depoluare acceptabil. Problema cea mai dificilã derealizat a reprezentat-o formarea amesteculuicarburant. Utilizând un echipament de injecþiemecanic ºi pornind de la forma ºi structura jetu-lui de combustibil injectat s-a determinat arhitec-turii camerei de ardere ºi poziþionarea punctuluide aprindere. Experimentele efectuate au avutca punct de plecare atât un fundament teoreticsolid, dar ºi simularea numericã.

The research in the field of mixture formationdesigned with a view to improving power, con-sumption and pollution performances, is mainlycentered on two directions:- improvement of engine functioning in the par-

tial loadings, by employing lean mixtures; inthese operating conditions the spark ignitionengine for automotive applications is oftenused uneconomically;

- improvement of mixture formation based ondevelopment of auxiliary equipment.

During the burning process in the commonspark ignition engine, there are two oppositephenomena. For the first period of the burningprocess, when the initialization of the flamenucleus is started, a reach mixture and less turbu-lence is necessary in the spark plug area.Otherwise in the second period of the burningprocess, when the flame is developed in theburning chamber, a great turbulence is neces-sary. To achieve those objectives there are twoissues:

- stratified charge, in the manner to obtain a richmixture only in the spark plug area;

- to separate the initialization of the fame nucle-us by the flame development in the combustionchamber.

Our concept is developed around the secondidea, which means to separate the initializationof the flame nucleus from the rest of burningprocesses. It is well known that many engine pro-ducers are using a lot of principal components ofthe engine like the cylinder block, the crankshaft,connecting rod, etc., for both the diesel and thegasoline engine.The existence of originally high-pressure injec-tion equipment and our own experience in thefield have made possible for us to approach thecomplex aspect of direct injection. We have cho-sen a convertible engine (76 mm cylinder bore,77 mm stroke) and have approached simultane-ously the problem of formation and combustionof lean mixtures.To study the latter we have chosen, on a prelimi-nary stage an injection pump with oil under pres-sure for greasing the pumping unit, a pump with-out discharge regulator. The classic pumpcamshaft was changed with a camshaft witheccentric profile. We have chosen a flame jetengine quite different from previously designedengines of this type by using a divided combus-tion chamber and in ensuring a ( = 0,47 ratiobetween the volume of combustion chambers,fig. 1. At this engine, the cylinder block, thecrankshaft, the connecting rods are from thegasoline engine, and the cylinder head and thecamshaft from the diesel engine. The pistonswere modified to obtain a convenient compres-sion ratio. The main combustion chamber is fedby a designed electronic fuel injection, the intakemanifold has no throttle, and the secondarycombustion chamber is fed by means of amechanical injection pump. The best momentfor beginning of injection is 75° before TDC, in

compression process.One of the difficult problems was to choose theignition point, because the procedure uses therotation movement of the air in the secondarycombustion chamber and fuel drops, which arecentrifugally separated according to their mass,different proportioning, are thus obtained. Theconvenient modeling of the connection channelbetween the two burning rooms effects thismovement also. At the stratified charge engines,which use the direct mechanical injection fuel,one of the problems is the form and the structureof fuel spray. To know what is happened into thesecondary combustion chamber, is necessary toknow rotations charging speed, the heat andmass transfer at the fuel drop level, and the mod-ification of air parameters during the compres-sion process. The charging speed motion in thesecondary combustion chamber depend on thepiston area Sp, the area of the connection chan-nel Sc, the crankshaft angle nc at the beginning ofthe compression process, the crankshaft angle nx

when the volume of principal combustion cham-ber is Vx , the piston speed wx, the dischargecoefficient μ in the connection canal, and thecrankshaft speed T. A fuel drop, in relativemotion related at warm air, change the initialdimensions do according to the time from the

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Lean Mixtures - a Reached PuropseUsing the Conversion of a Classical Internal Combustion EngineDr. Adrian SACHELARIE, Assoc. ProfessorDr. Radu GAIGINSCHI, Professor

Technical University "Gh. Asachi" IaºiAutomotive and I.C. Engines Department

Bd. D. Mangeron 61 bisIaºi-700059-Iaºi

Fig. 1 The stratification solution

6 Ingineria Automobilului Nr.2

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injection start and the vaporization coefficient k.The air interesting parameters during the com-pression process are the density Dac and the vis-cosity μac. The development of fuel spray, in thesecondary burning chamber depend on the pres-sure and the temperature of fuel mixture duringthe compression process pac and Tac, the air con-stant Ra, the compression ratio e, the air densityDa, the crankshaft speed n, the constructive ratio( and the polytropic exponent n1.The computer simulations presents in fig. 2, theevolution of the main parameters from the se-condary burning chamber, according to the

crankshaft movement or time. The graph fromfig. 3 presents the fuel drop vaporization (withdiameter between 50…100 μm), according tothe crankshaft movement or time, and demon-strate that in our conditions, the air motion intothe secondary burning chamber has no majorinfluence on the trajectory of the fuel spray. Theair motion works over the vaporized fuel dropsfrom the spray. They make few complete rota-tions in the burning chamber, from the injectionmoment since the ignition time. The experimental results, fig. 4, shows the idlerunning characteristic as compared to classicengine characteristic; the figure also shows volu-metric efficiency, air excess coefficients andexhaust gases temperature variations.Fig. 5 shows the load characteristic and the vari-ation of other significant parameters, at 1600 rpm

speed of the engine. Significant results have alsobeen obtained for partial loading as which can beused to drive the automobile at stabilized speed.So for a 22 HP effective power at 3000 rpm at1,38 air-excess coefficient was obtained, 0v = 0,79volumetric efficiency, 247 g/HP h effective speci-fic consumption. For another characteristicengine operating condition for a 27 HP power,3000 rpm, a 1,23 air-excess coefficient, 0v = 0,79volumetric efficiency and 229 g/HP h effectivespecific consumption were obtained.In conclusion, the experience stored in the fieldof injection equipment has made it possible toapproach complex problems beginning withmodification of mixture formation for existentengines and ranging to new solutions for forma-tion and combustion of lean mixtures which is afield that can yields still unexplored possibilities.Economic advantages and increased cyclic stabi-lity plead for the use of the described procedurein the common spark ignition engine feeded bydirect fuel injection. Working on a well-knownengine, the obtained gain of performance con-tributes to the improvement of dynamic and con-sumption qualities of these.

Informaþii suplimentare puteþi obþine scriind la urmãtoarea adresã: asachelarie@yahoo.com

1. Gaiginschi, R., Rakoºi, E., Sachelarie, A., Agape, I., Au sujet d'un moteur a jet

de flamme, Buletinul Institutului Politehnic din Iaºi, Tomul XLII (XLVI), fasc 1-

2, secþia V, construcþii de maºini 1996.

2. Rakoºi, E., Sachelarie, A., Agape-Comsa, I., Conversion possibilities related to

spark-ignition engine for opperating by inhomogeneous lean mixtures, The 6-th

International Conference ESFA '98, Bucharest 1998.

3. Rakoºi, E., Gaiginschi, R., ºa., Procedure for improvement of the spark-engines

operating by mixture stratification as effect of centrifugal movement. Buletinul

Institutului Politehnic din Iaºi, Tomul XLIV (XLVIII), fasc 3-4, secþia V, con-

strucþii de maºini 1998.

4. Sachelarie, A.., Rakosi, E., Roºca, R. , The importance of fractionate composi-

tion of injected fuel in a stratified charge engine, The 6-th International

Conference ESFA '98, Bucharest 1998.

5. Sachelarie, A.., Rakosi, E., Roºca, R. Agape-Comºa, I, Gaiginschi, R., Câteva

aspecte privind compoziþia fracþionatã a jetului de combustibil, A VIII-a

Conferinþã Internaþionalã de Autovehiculutie Rutiere CAR 2000, Piteºti.

6. Zugrãvel, M., Gaiginschi, R., º.a. Realizãri ale colectivului Catedrei de Motoare

ºi Autovehicule rutiere ]n domeniul formãrii amestecului la M.A.S., Termotehnica

Româneascã - '96, vol I, Ed. "Gh.Asachi" Iaºi 1996.

7. xxx Multi-Purpose internal combustion engine. Pat. USA., cl.123., Nr. 312507

References

Fig. 2 The evolution of the main parame-ters from the secondary burning chamber

Fig. 3 The fuel drop vaporization Fig. 4 The idle running characteristic

Fig. 5 The load characteristic and thevariation of other significant parameters

7

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KEYWORDS - Aerodynamic loads, under-hood airflow, underbody drag of vehicle,dimensionless characteristic indicators, opti-mum drag value

REZUMATStudiul aerodinamic al curgerii pe structurainferioarã a automobilelor

Comportamentul dinamic al automobilelor înceea ce priveºte stabilitatea, manevrabilitatea,sensibilitatea la rafale laterale, cu consecinþedirecte asupra consumului de combustibil ºizgomotului generat de interacþiunea cu aerulatmosferic, este influenþat decisiv de forþeleaerodinamice care acþioneazã asupra acestora. Pânã de curând, forma exterioarã a caroserieia reprezentat pentru inginerii proiectanþiprincipala preocupare din punct de vedereaerodinamic, geometria structurii inferioareavând un rol secundar în procesul de definireal unui automobil, sau a fost complet neglijatãprecum în cazul maºinilor de teren. Studiirecente au arãtat cã pentru un automobilmodern aproximativ 45% din rezistenþa aero-dinamicã se datoreazã formei caroseriei, 30%roþilor ºi pasajelor acestora ºi 25% geometrieistructurii inferioare. Dupã cum se observã,îmbunãtãþirea caracteristicilor aerodinamiceale geometriei structurii inferioare ale autove-hiculelor reprezintã un factor semnificativ înprocesul de reducere rezistenþei aerodinami-ce, implicit ºi a consumului de combustibil.Recent, managementul curgerii aerului pesub vehicul a devenit una din problemelemajore ale proiectãrii automobilelor.În acest sens, în lucrare sunt evidenþiaþi fac-

torii care influenþeazã rezistenþa aerodinami-cã generatã de interacþiunea aerodinamicãdintre structura caroseriei inferioare a unuiautomobil ºi calea de rulare, având ca punctde plecare modelul teoretic expus în referinþa[3]. Studiul este însoþit de un exemplu de calculpentru un automobil SUV, a cãrui geometrie astructurii inferioare a fost modelatã ca tunelVenturi, fiind evidenþiate astfel posibilitãþile deoptimizare a rezistenþei aerodinamice.

The aerodynamic performances of the vehi-cles are characterised using specific coeffi-cients, dimensionless, as drag and lift coeffi-cients. Using of these as the measure of thestate of the art in the vehicle aerodynamics,the continuously progress is possible in thisfield. In this context, because the decomposi-tion of the aerodynamic forces into measura-ble components would facilitate the optimisa-tion design process of the carriage body, inthe previous study [3] was presented a theo-retical method for computing of the drag dueto the underhood airflow. In this sense, wasproposed the decomposition of the globaldrag, D, into two components, Dext and Dub.The first one is the drag due to the flow uponthe external surface of the vehicle, having therate flow Qext. The second term represents thedrag due to the flow under the body of vehi-cle, in the space determined by the lower sur-face of the vehicle and the road, treated as aconvergent-divergent air nozzle with the flowrate Qub. Also, dimensionless indicators weredefined to characterise the underhood airflowas following: cDub, drag coefficient of the

underbody, KDub, coefficient what representthe ratio between underbody drag and totaldrag and KQub, coefficient what characterisethe participation of the underbody flow rateon total flow rate Q.

In this paper are emphasised the main factorswhich having importance on the underbodydrag and which may lead to optimising stepswith respect to the aerodynamics of the vehi-cles. The study is illustrated by means of anumerical exemplification performed with aSUV model having the underbody geometrymodelled as a Venturi tunnel. The parametricstudy of the underbody drag coefficient per-mits the plotting of a diagram of this as func-tion of the dimensionless indicators, whichreveal an optimum of cDub.

THEORETICAL CONSIDERATIONSThe total drag D of the vehicles is determinedby the dynamic interaction between the vehi-cle, adequately shaped, in motion, and theatmospheric air from upstream, motionless.The air envelopes and flows from the leadingedge (the zone of the radiator) on the lateral,upper surface and under the vehicle. It can becomputed using the following Equation:

(1)

where:D - is the air density;<∞ - is the relative velocity between

vehicle and air;cD - is the drag dimensionless coeffi-

cient in body axis coordinates;

Study of the UnderhoodAirflow on Aerodynamics of the MotorcarsHuminic Angel, Chiru Anghel, Huminic GabrielaTransilvania University of Braºov, România

AcvñD D2

2∞⋅=

8 Ingineria Automobilului Nr.2

Supliment Auto Test

A - is the area of the maximum crosssection of vehicle.

The drag coefficient cD has a complex deter-mination, endowed with numerous construc-tive and exploiting influence factors. It isexperimentally determined through tests inwind tunnels.As the decomposition of the aerodynamicforces into measurable components wouldfacilitate the optimisation design process ofthe cars' body, in the previous study [3] waspresented a theoretical method for computingof the drag due to the underhood airflow. Inthis way, there was proposed the decomposi-tion of the global force of road resistance,according to the Equation:

(2)

where:Dext - the drag due to the flow upon the

external surface of the vehicle,having the rate flow Qext (seeFigure 1);

Dub - the drag due to the flow under thebody of vehicle, in the space deter-mined by the lower surface of thevehicle and the road, treated as aconvergent-divergent air nozzlewith the flow rate Qub.

The sum of two mentioned rate flows repre-sent the volume of air what enveloping thevehicle, dislocated in time unit :

(3)

The main components of Qub are given by:

- the stationary air, in atmospheric conditions,motionless, upstream, "swallowed by themobile nozzle", having the flow rate Q1;

- the inferior branch of the stream generatedthrough impact at the leading edge, whichflows under the vehicle, having the flow rateQ2; an important fraction of this is used, gene-rally, for cooling in the engine compartment.

For this theoretical approach the air suc-tioned from lateral sides by means of freeejection was neglected. Also, considering thatthe resultant fluid is homogeneous in theentire cross section of the nozzle b x h, for thesecond component of the drag of vehicles,Dub, were proposed the following Equation:

(4)

where:- is the coefficient of the equivalent

hydraulic rezistance of the nozzle; < - is the average velocity of the air

through the section of the nozzle;

Also, the following dimensionless indicatorswere defined to characterise the underhoodairflow process:

KDub - is the coefficient what representthe ratio between underbody dragand global drag defined as productof three dimensionless factors,Equation (5);

KQub - is the coefficient what characterisethe participation of the underbodyflow rate on total flow rate,Equation (6);

(5)

where:- is the relative drag;

- is the relative area;

- is the relative velocity.

(6)

In this way, the underbody drag coefficientCDub can be expressed with the Equation:

(7)

NUMERICAL APLICATIONThere are considered the following dates asfor experimental model ARO 26 of ARO SA,Romanian Automotive Company: A=2.6 m2,b=1.7 m, l=4.1 m, h=0.42 m, hus=hds=0.54m, cx=0.443 (experimental). For the air wasconsidered a density as for standard atmos-phere: D=1.205 kg/m3 The calculus for thecoefficient of the equivalent hydraulic rezis-tance of the nozzle (a quick one, on the firststage) was made according with [2. 237] forI0=3.75 m: .en=3.345. Results concerning the variation of KDub andCDub with KQub are presented in Figure 2 con-sidering Q2=(0.5 - 8.0)%Q as parameter.

Figure 3 depict the underbody drag variationwith the reference velocity. The computationswere made for 5 speeds, as following:

CONCLUSIONSAs can be observed in previous Figures, theincreasing of the flow rate under the vehiclehas a negative impact on underbody drag ofvehicle, also for total drag. As an optimising measure is necessary tolimit, much as possible, the flow rate Qub

under the vehicle through the control of itscomponents. Concerning the flow rate Q1

(swallowed by the mobile nozzle) this can beeasily decreased using auxiliary structural ele-

∞

=vvñb hæD e nub

3

2

3

⎟⎟⎠

⎞⎜⎜⎝

⎛==

∞vv

Ab h

Cæ

DDK

D

e nubDub

3

⎟⎟⎠

⎞⎜⎜⎝

⎛=⋅=

∞vv

Ab hæCKC e nDDD ubub

Cæ

D

e n

Ab h

3

⎟⎟⎠

⎞⎜⎜⎝

⎛

∞vv

AvQQQ ubext ∞=+=

Fig. 1 - The main geometrical characteristics of the nozzle at the level of vehicle under-body

bæe n

ubext DDD +=

QQK ub

Qub=

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ments, as a special profiled aero-dynamic radiator shell.The second component of theQub, respectively flow rate due tothe stream generated throughimpact in the leading edge of thecar, can be reduced using a solu-tion with lateral apertures toexhaust the air from engine com-partment. Also, this method canbe used to manage of the airflowon lateral side of the car, in orderto avoid the detachment of theflow from these areas.Obviously the decreasing of Qub

can be obtained through thediminution of the ground clear-ance of the vehicle, as for therecent automobiles which havevariable ground clearance withspeed. In this way, diagrams ofaerodynamic coefficients can beplotted, as one shown in Figure4, where is depicted the variationof CDub versus KQub as function ofground clearance in range (65%- 100 %)h (ground clearance inbasic configuration).

As can be observed, dependingon flow under vehicle, decreas-ing of ground clearance is notalways a proper solution for thereduction of drag. In studiedcase, for a smaller ground clear-ance from usual configuration inamount of 35%, the drag coeffi-cients CDub and implicit CD areincreasing. Thus, for Q2=0.08Qand h=65%, the value of CD isincreasing to CD=0.45 (see Table1). For an optimum situationfrom aerodynamic point of view,ground clearance must bedecreased simultaneously withthe flow rate under the vehicle.Also, experimental measure-ments [4] performed on a 1:6scale model having the under-body reproducing a Venturi con-figuration tunnel show animproving of the aerodynamiccharacteristics of the car, empha-

Fig. 2 - Variations of KDub and CDub with KQub

Fig. 3 - Variations of D and Dub with v∞∞ and Q2<∞∞

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sised mainly by the lift coeffi-cient.To this end we mention that thepresented method for the aero-dynamic underhood evaluationcan be used for optimising of theflow around vehicles even in a

very early design stage. Also, inorder to have best results con-cerning the dynamic behaviour ofthe cars there is necessary anactive control of their groundclearance according with thespeed and underbody flow.

Table 1 Q2=0.5% Q2=2%Q Q2=4%Q Q2=6%Q Q2=8%QKQub 0.298 0.302 0.319 0.336 0.353

h=95% CDub 0.125 0.143 0.168 0.196 0.228CD 0.436 0.437 0.437 0.438 0.440KQub 0.259 0.272 0.289 0.306 0.323

h=85% CDub 0.118 0.136 0.164 0.195 0.228CD 0.429 0.430 0.433 0.436 0.440KQub 0.229 0.242 0.259 0.276 0.293

h=75% CDub 0.111 0.130 0.160 0.193 0.231CD 0.422 0.424 0.429 0.435 0.443KQub 0.199 0.212 0.229 0.246 0.263

h=65% CDub 0.104 0.125 0.157 0.195 0.238CD 0.415 0.419 0.426 0.437 0.450

1. Sumatran V., "Vehicle aerodinamics", SAE Inc, PT-49 USA, 1996, ISBN 1-56091-594-3.2. Idelcik I., "Calculus of the hydraulic resistances", Editura Tehnica, Bucuresti, 1984.3. Benche, V., Huminic, A., "Theoretical evaluation of the underbody drag of theroad vehicle", , CONAT Congres, CONAT200041009, Brasov, Romania, 2004.

4. Chiru A., Huminic A., "Experimental Study Concerning the Influence of theGround Clearance for a Car having the Underbody as Venturi Tunnel", CAR2005Automotive Congress, CAR20051193, Pitesti, Romania 2005.

References

Informaþii suplimentare puteþi obþine scriind la urmãtoarea adresã: angel.h@unitbv.ro

Fig. 4 - Parametric variation of CDub versus KQub

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1. IntroductionConception, intérieurs, moteurs, bruits, vibra-tions, éclairage, la simulation est partout. Lavoiture 100 % numérique, entierementsimulèe, n'est pas encore d'actualité, mais lesordinateurs et les logiciels progressent telle-ment vite que rien ne semble impossible (parexemple, dans les dernières 15 annees, la fre-quénce des microprocesseurs utilisés pour lesordinateurs habituels est passée de 16 MHz à2 - 3 GHz). Virtuel, réel, la frontière est deplus en plus mince. Aujourd'hui, grâce auxprogrès de l'informatique, le monde virtuelest devenu une réalité. La conception et lamodélisation d'objets se font désormais quasi-ment toujours sur ordinateur. Les progrèsréalisés dans la simulation en temps réel, per-

mettent de proposer des logiciels capables detout créer.L'industrie des automobiles est aujourd'huisous pression avec des processus dedéveloppement de plus en plus courts. Pourcette raison, un intérêt majeur de la simula-tion est qu'elle doit permettre de trouver lessolutions de plus en plus tôt, pour obtenir lesmeilleurs produits.L’un des principaux avantages de la simulationnumérique de l’automobile c’est la possibilitéde reproduire exactement certains paramètrescomme la vitesse du véhicule, l’accélération oules conditions de roulage. Les résultats du cal-cul offrent une bonne vue des phénomènespassés dans une session de simulation. Cesrésultats peuvent couvrir une plage plus large

de l’influence des parametrès, avec des coutssensiblement petits, en comparaison avec lesessais et les mesurages effectués sur la route,sur banc d’essai ou sur les pistes d’essais spé-cialement aménagés (un véritable test sur bancd'essai peut durer plusieurs mois, alors qu'unesimulation de 200000 km est réalisée enquelques jours, /20/). Ils peuvent soutenir leslogiciels spécifiques d’essai des automobiles etaussi de compléter des bases des données déjàexistantes.Le tout numérique dans la construction auto-mobile n'est pas pour demain, mais cetteutopie ne semble plus en être une, desgrandes compagnies, proposant des pro-grammes de simulation numérique de plus enplus évolués, /17, 22, 23/.

Etude par simulation numerique de l’influence des moments de changement des vitesses sur les performances dynamiques et d’economie

Catalin V. ZAHARIA, Ion TABACU, Adrian C. CLENCIUniversity of Pitesti, Automotive Departmentemail: catalin.zaharia@upit.ro

Pierre PODEVIN, Georges DESCOMBESConservatoire National des Arts et Metiers,

Chaire de Turbomachines et Moteursemail: podevin@cnam.fr

Fig. 1. Image de niveau supérieur du modèle Simulink

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2. La modélisation dynamique du véhiculeCette approche de modélisation du véhiculeest basée sur les essais effectués sur un bancmoteur à volant d’inertie, /11, 12, 18/. En con-séquence, pour que la validation du modèlesoit possible, le raisonnement a été fait auniveau du volant du moteur. Autrement dit, lamasse en translation du véhicule a été réduiteau niveau du volant du moteur en utilisantune masse en rotation (un volant) avec uneinertie équivalente identique.Le but de cette étude a été de réaliser unmodèle de simulation apte à effectuer d’ac-célérations avec le changement des rapportsdes vitesses. Pour la validation on a utilisé lesessais d’accélération effectués sur le bancmoteur à volant d’inertie du CNAM de Paris,/8, 9, 12, 18/.L’image de niveau supérieur du modèleSimulink réalisé est illustrée dans la figure 1,/18, 19/. Dans la structure du modèle on peutobserver les modules spécifiques des car-tographies du moteur et de la consommationde carburant, des résistances à l’avancement,du système de control de la transmission, etdernierèment, le module additionnel de cal-cul du régime moteur en concordance avec leprocessus de changement des rapports.On observe qu’un modèle Simulink est, eneffet, une collection d’objets (modules) inter-connectés, avec une signification physiquebien déterminée. Une telle démarche imposeune attention spéciale pour s'assurer d’unerelation causale correcte entre les objets du

modèle; son non respect risque de provoquerl’apparition de boucles causales, qui vont com-promettre le modèle de simulation. Ils sont,finalement, l’expression d’un modèle de simu-lation non conforme implémenté ouautrement dit, qui ne décrit pas en conformitéle phénomène physique modélisé.On n’insiste pas dans cet article sur la descrip-tion du modèle de simulation car il a été bienprésenté dans les ouvrages /18, 19/.Néanmoins, on souligne le fait que l’obtentionde résultats corrects dans une telle étude estconditionnée – premièrement – par l’exis-tence d’un modèle fiable de la source d’én-ergie (i.e. le moteur thermique). De ce pointde vue, l’approche globale dans la modélisa-tion du moteur consiste à raisonner en „boîtenoir“: à l’entrée il y les signaux de régime etde charge (l’enfoncement de la pédale d’ac-célération) tandis qu’a la sortie il y a le couplemoteur et la consommation spécifique. Lesfonctions de transfert entre l’entrée et la sor-tie sont basées sur les résultats expérimentauxeffectués sur le banc moteur à volant d’iner-tie. En fait, on a utilisé une approche mixtequi consiste dans la combinaison des résultatsstationnaires et non stationnaires, /18/.Ce type de modélisation du moteur est plutôtutile pour l’étude de l’influence des carac-téristiques de la transmission et/ou de l’auto-mobile sur les performances dynamiqueset/ou d’économie et pollution.En ce qui concerne les fonctions de transfertmentionnés ci-dessus, dans la figure 2 on

présente la fonction analytique qui approximeau mieux la surface déterminée par les pointsexpérimentaux de couple moteur, /13, 18/.Aussi la figure 3 constitue la représentationgraphique de la variation de la consommationspécifique effective. Pour la déterminationdes fonctions analytiques on a utilisé le logi-ciel JANDEL, /21/, spécialisé dans la résolu-tion des tels opérations, par l’utilisation de laméthode des moindres carrés.3. Resultats et discussionsLa cause du processus d’accélération est l’en-foncement de la pédale d’accélération dontson scénario est le suivant: sur les premiers 4secondes est imposé le fonctionnement stabil-isé, et dans les 2 suivants secondes est sollicitéle niveau maximum de charge, qui sera main-tenu jusqu’au fin de la simulation.La simulation du processus d’accelerationavec le changement des vitesses se fait en par-tant de 3ème vitesse, /12, 15, 18/. Par con-séquent, l’enfoncement brusque de la pédaled’accélération détermine une augmentationrapide du couple moteur en rapport avec lecouple résistant (graphe a, figure 4). Dans legraphe b, on observe les moments du change-ment des vitesses, qui sont choisies fonctiondu régime moteur. En concordance avec cesmoments, dans les graphes c et d, sont présen-tés les valeurs des rapports de transmission,respectifs des moments massiques d’inertieéquivalente.La variation du couple moteur avec le régimeest répresentée dans le graphe e, où on peut

Fig. 2. Surface générée du champ d’offre du moteur XUD11 ATE, R2 = 0,997

Fig. 3. Fonction ce = f(N, cmot), R2=0.991

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remarquer, également, l’allure croissante ducouple résistant, qui impose un fonction-nement du moteur aux charges de plus en plusgrandes. Donc, le fonctionnement du moteurse translate sur les zones des rendements plusélevés (fig. 5).En ce qui concerne la variation de la vitesse,dans le graphe f on observe le fait que le par-cours de l’intervalle (30 . 152,6) km/h s’ef-fectue en 39 s.De point de vue performances d’économie,

dans la figure 6 on remarque l’évolution de laconsommation totale de carburant.L’avantage principal du modèle de simulationréalisé consiste dans la possibilité d’effectuerdes études comparatives sur l’influence desmoments de changement des vitesses sur lesperformances dynamiques et de consomma-tion de carburant.Dans la figure 7 on presente les résultatsd’une telle étude:- en analysant la figure 4, a, on a constaté que

le passage dans la 4ème vitesse s’effectue aprèsl’attouchement de la valeur maximale du cou-ple moteur, motif pour lequel, dans un pre-mier cas, on a désiré simuler le processusd’accélération dans les conditions quand cechangement se réalise dans le moment ducouple maximum (N = 2180 tours/min -changement précoce),- le 2ème cas simule represente le passage dansla 4ème au régime moteur N = 3250 tours/min(changement tardive).

a. Cmot instantane et Crés vs. temps de simulation b. N vs. temps de simulation

c. ibv vs. temps de simulation d. J* vs. temps de simulation

e. Cmot (100%), Cmot instantané et Cres vs. N

Fig. 4. Performances dynamiques sur l’essai d’accélération avec le changement des vitesses

f. vauto vs. temps de simulation

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Ainsi, comme on peut observer en figure 7, seconfirme la contradiction entre la manière deconduite économique et la conduite sportive.Dans le premier cas, on poursuit une consom-mation réduite de carburant comptant sur lepassage précoce dans les vitesses supérieures,tandis que pour le deuxieme cas, on vise unecroissance rapide du régime moteur par lechangement tardive des vitesses.Pour des raisons de clartée des graphes, enfigure 7, on n’a pas superposé les évolutionstemporelles des paramètres enregistres dansle 3ème cas analyse: changement precoce aussien 4ème qu’en 5ème vitesse (N3->4=2180 tr/min,N4->5=3200 tr/min). Les résultats de cette si-mulation ne font que soutenir l’affirmationantérieure, puisque le changement prècocedes deux rapports a déterminé une vitessemaximale et une consommation totale de car-burant légèrement inférieures à cellesobtenues dans la première situation analysée(150,4 km/h, respectif 168,4 g).

Tous ces faits étant présentés, on considèreimportant de souligner que le changementd’un rapport ne doit pas, dans aucun cas, seproduire sur l’allure ascendante de la courbedu couple moteur, parce que le règimemoteur, rèsultè suite à la sélection du nou-veau rapport, ne fait que déplacer le point defonctionnement du moteur dans une zonecaractérisé par des valeurs même plus petitesdu couple moteur (v. figure 7, a . 1er cas). Ence qui regarde la manière de conduitesportive, il est important que le choix dumoment de changement de la vitesse soit faitainsi que celle-ci ne génère pas un régimemoteur trop petit pour reprendre l’accéléra-tion dans le nouveau rapport engagé.4. ConclusionsGrâce à l’utilisation du banc moteur à volantd’inertie, pour réaliser la simulation duvéhicule automobile on a pris en considéra-tion une stratégie apte à reproduire le fonc-tionnement de ce banc. En ce qui concerne la

modélisation du champ d’offre du moteur, ona éssaye d’utiliser des fonctions analytiques,qui approximent la surface caractérisée parles points prélevés expérimentalement.Un modèle virtuel Simulink a été aussi réalisépour effectuer une analyse en transitoire desessais d’accélération avec le changement desvitesses dont les résultats ont été validés àl’aide d’expérimentations menés sur le banc àvolant d’inertie.Quel est l’avantage du modèle? Il offre la po-ssibilité d’effectuer des études comparatives,en ce qui concerne les performancesdynamiques et de consommation de carbu-rant, sur l’influence des moments de change-ment des vitesses ou bien de valeurs de ra-pports de transmission etc.En tenant compte de la nécessité actuelle delimiter les émissions de CO2 responsables engrande partie de l’effet de serre, il se révèleparticulièrement important que, pour unmoteur donné, des études comparatives parsimulation numérique puissent être menéessur l’influence des caractéristiques de la trans-mission sur la consommation de carburant.Bien entendu, si le choix de la transmission estprimordial sur la consommation de carburant,ce choix a aussi une influence primordial surl’agrement de conduite, paramètre très subjec-tif qui peut malgré tout lui aussi être pris encompte dans les programmes de simulation.REZUMATConcurenþa, atât de prezentã în industria deautomobile, legislaþia de protecþie a mediuluiînconjurãtor, cerinþele ºi gusturile cumpãrãto-rilor de automobile, au impus, în ultimii 20 deani, reducerea timpului dedicat dezvoltãriiunui nou model de automobil.Aceastã nouã tendinþã a impus cedareaparþialã a locului cercetãrii experimentale, înfavoarea ingineriei conceptuale ºi a studiuluivalidãrii virtuale, realizatã prin simularea pecalculator.Încercãrile de accelerare efectuate pe standulmotor cu volant de inerþie al CNAM Paris aufurnizat o importantã bazã de date, necesarãconcepþiei unui program de simulare afuncþionãrii automobilului.Aºadar, lucrarea prezintã un model de simu-lare a automobilului, capabil sã reproducãfuncþionarea standului motor cu volant deinerþie dar ºi efectuarea unor studii compara-tive legate de influenþa parametrilor trans-misiei asupra performanþelor globale ale unuiautomobil pe perioada accelerãrilor.

Fig. 5.Rendement effec-tif vs. temps

Fig. 6. Evolution dela consommation

de carburant

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1. Untaru, M. et al - Dinamica autovehiculelor pe ro.i, EDP, Bucure.ti, 19822. Cruceru, D., Tabacu, I. Automotive Powertrain Modeling & Simulation, Ed.Univ. Pitesti, 20043. Deguy, F. - Prediction des performances d’un vehicule a moteur turbo surali-mente entenant compte des temps de reponse moteur, Rapport de stage, ESTACA 19884. Dupre, R. - Contribution a l’etude du temps de reponse d’un moteur diesel turbosuralimente, Memoire d’Ingenieur, Conservatoire National des Arts et Metiers,Paris, FRANCE, 19925. Ghiulai, C.,Vasiliu, Gh. - Dinamica autovehiculelor, Editura Didactic. .iPedagogic., Bucure.ti, ROMANIA, 19756. Harari, R., Sher, E. - Measurement of engine friction power by using inertia tests,SAE Paper, no 9500287. Lang, T. - Test of a fast response Zollner eddy current dynamometer on anAVLGraz Testbed, SAE Paper, no 9523088. Le Guen, H. - Moyens specifiques d’essais, Doc B 2 960, Techniques del’Ingenieur, traite Genie mecanique9. Negru., E., Soare, I., T.nase, F., Bejan,N. - Incercarea autovehiculelor, EdituraDidactic. .i Pedagogic., Bucure.ti, ROMANIA, 198310. Parois, A. - Suralimentation par turbocompresseur, Doc B 2 631, Techniques del’Ingenieur, traite Genie mecanique11. Podevin, P. - Contribution a l’etude de la reponse transitoire d’un moteur acombustion interne soumis a une acceleration, These de doctorat, ConservatoireNational de Arts et Metiers, Paris, FRANCE, 199612. Podevin, P. - Simulation des accelerations d'un vehicule sur un banc a volant

d'inertie, SIA (Societe des Ingenieurs de l'Automobile), 716, P.62-67, Paris,Octobre 199713. ªerban, F. - Studiul circuitelor de reglare ale autovehiculelor in vedereaimbun.t..irii economicit..ii .i dinamicit..ii acestora, These de doctorat, UniversiteTransilvania de Bra.ov, Brasov, ROUMANIE, 199914. Tabacu, I. - Transmisii mecanice pentru autoturisme, Editura Tehnic.,Bucure.ti, ROMANIA, 199915. Tabacu, I., Zaharia, C., Clenci, A., Boroiu, A. - Simularea regimurilor tranzitoriipe un stand motor cu volant de iner.ie, Conferin.a Mecanica Solidelor, Pite.ti,ROMANIA, 200316. Tabacu, I., Marinescu, D., Secar., M. - Optimizarea grupului motor transmisie,Editura Universit..ii din Pite.ti, ROMANIA, 199917. Zhang, J., Qingchun, L. - CAD of Engine Dynamic Test Bed based on hybridsimulation, FISITA World Automotive Congress, Seoul 200018. Zaharia, C. - Studii teoretice .i experimentale privind evaluarea performan.elorunui autoturism supus unor accelera.ii, Tez. de doctorat, 18/12/2006, Universitateadin Pitesti19. Zaharia, C., Clenci, A., Podevin, P., Descombes, G. - Dynamic model for thesimulation of a vehicle’s unsteady operation, COFRET 2006, Timisoara,ROUMANIE20. **www.jurnalauto.com21. **AISN Software, Jandel Scientific . TableCurve3D22. **The MathWORKS, Matlab for Windows, v.6.1 h23. ** Advisor User’s Guide

Bibliographie

RemerciementsOn exprime les plus sincères remerciements à Monsieur Michel FEIDT, professeur à l'Université Henri Poincaré de Nancy et à l'ADEME, Agence del’Environnement et de la Maîtrise de l’Energie de France d’avoir financé la réalisation de ce travail entre les années 2003-2006, grâce à une politique decoopération scientifique et universitaire avec les Pays de l’Europe Centrale et Orientale.

a. Cmot, Crés vs. temps de simulation

c. vauto vs. temps de simulation d. Consommation totale vs. temps de simulation

b. N vs. temps de simulation

Fig. 7. Analyse de l’influence des moments de changement des vitesses sur les performances dynamiques et d’économicité

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Rezumat:Electrificarea automobilului: articolul de faþãoferã o imagine panoramicã, bogat ilustratã aprincipalelor obiective ºi soluþii ,cu rezultatela zi, cu privire la utilizarea tot mai pro-nunþatã a energiei electrice pe automobil, învederea reducerii consumului de combustibilºi a poluãrii în traficul urban, în condiþii desiguranþã ºi confort uºor mãrite, la preþuri deinvestiþie în echipamente electrice/electronicede putere moderatã.

A. Scope and targets

The scope of this paper is to describe electricpower conversion and its power electronicsdigital control for new functions on board ofautomobile for energy saving, low pollutionand more safety and comfort.

What is it?%E = peak electric power x 100 / (peak elec-tric power + peak ICE power) = Pel x 100 /Pel + PICE

%E = (5-10%) for ICE vehicle with ISA(integrated starter alternator) at 14Vdc or42Vdc %E = (10-15%) for Mild EHV at 42 Vdc %E = (30-50%) for Full EHV at 500 Vdc and42 Vdc%E = 100% EVWhy %E?Because of:- energy savings and less pollution ( up to 50%less)- increased safety and comfort Targets of automobile electrifications aresuch as in Fig. 1:- 42Vdc power bus and converters- electric power steering assist- electric steering by wire- electric braking by wire- electric throttle and valve control- electric active suspension damping - direct fuel injection- integrated Starter/Alternators in HEV andEV (with mixed: ICE and electric powertrains)

B. Hybrid electric vehicles (HEV),fuel econo-my so far

As seen in Fig. 2 the first commercial HEVssuch Honda Insist, Honda Civic, Toyota Priusand Ford Escape SUV provide significant fuelsavings at the European fuel costs, around33% per year, for strong HEV ( 66% electrifi-cation ratio). But the city driving advantagesare much better.

Figure 2 Automobile electrification results

Automobile Electrification TrendsIon Boldea, IEEE FellowDepartment of Electrical Machines and Drives, University Politehnica of Timisoara, V.Parvan 2, RO - 300223 Timisoara, Romania, Tel. +40-56-204402email: boldea@lselinux.utt.ro

Figure 1 Automobile electrification targets

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C. Target 1: The 42Vdc/14Vdc power bus

The key to electrification is power electronicsdigital control of various functions on auto-mobile by electric motors. To make it moreeconomical the 42Vdc bus was selectedrecently as a compromise for drivers safety.An advanced 42Vdc power bus (commercialonly on Toyota Crown Royal mild HEV)should contain an integrator starter/alterna-tor with full power electronics control that notonly produces electric power on board, but,also through a belt transmission, starts theICE in a few tens of seconds after automaticICE shutdown (to save energy), and then itcontributes to fast acceleration and finallyyields a 15% fuel savings.

Figure 3 Future 42 Vdc bus with ISA ( inte-grated starter alternator)

D. Target 2: Electric power steering assist

Using a low volume, high efficiency, fast andlow storage pulsation permanent magnetbrushless motor (PMSM) with position tri-ggered power electronics control is the way togo for power steering assist and most majorautomatic manufacture have installed one onone of their very recently models still at theexisting 14Vdc bus. It may be used for front orrear drive trains.

Figure 4 Electric power steering assist (with PMSM)

E. Target 3: Steering by wire

Mechanical decoupling between the driver'swheel (Fig. 5) and the vehicle steering systemis common on aircraft and vessel drive-trainsbut is still in the laboratories for automobile,due to safety precautions.

Figure 5 Steering by wire

Steering by wire includes the electric powersteering assist for driving feeling preservationbut it adds the main electric drive that doessteering; both electric motors are controlledconcurrently based on road-wheel and turn-wheel measured (and estimated for redun-dancy) positions.

It is supposed to increase safety and reduceenergy consumption.

F. Target 4 Electric braking by wire

Control of electric brakes based on onlinevehicle dynamic evolution, with the driver stillactivating the brake pedal but with CPUdeciding, based on numerous vehicle statevariable estimators, deciding what to doincluding the steering of vehicle after the driv-er lost conscience, is the ultimate goal of elec-tric braking by wire (Fig. 6).

Figure 6 Electric braking by wire

G. Target 5 Electromagnetic valves

The 16 typical valves on a 4 cylinder, 1.6 literICE are standardly activated by a commoncame shaft and they consume at best 1.5kW(average).Fuel savings of (10-15)% can be obtained byindependent (and eventually gradual) valvesdriving with electric motor at variable speed:rotary motors (Fig. 7a) or linear motors ( Fig.7b), all with permanent magnets to cut volu-me and electric losses. A 3 millisecond aver-age drive cycle shows the extraordinarydemands from the electric drives.

Figure 7 Electromagnetic valves with rotary PMSM

Despite worldwide efforts the electromagne-tic valves are still not commercial, mainly dueto their too large peak power (average inputpower is already ok) which, for peak powershaving, needs super-capacitors that are stillvery expensive. However this is one more reason to try fur

18 Ingineria Automobilului Nr.2

Supliment Auto Test

ther, especially for multi-cylinders ICE forlarge cars, lorries or city buses.

Figure 7 Electromagnetic valves withlinear motors

H. Target 6 Electric active suspension

Figure 8 Active electric damping with (a)linear actuator (b) rotary actuator

To dump low frequency car-cabin oscillations,an electric damping system using rotary or li-near electric motors (Fig. 8), controlled byindividual power electronics converters con-nected to the common 42Vdc, have been pro-posed already in early nineties with a fewalready apparently commercial embodiments(Toyota's Lexus). The fact that the active electric dampingallows for bidirectional fast power flowbetween vehicle corners, makes the averagepower absorbed from the power bus small; its

peaks however have to be "shaved" by super-capacitors, which are still expensive.

I. Target 7 Exhaust- gas electric energy recovery

Mounting a hyper speed (80,000 rpm) turbine(of up to 6 kW(peak) on the exhaust trajecto-

ry (Fig. 9)) that drives an electric motor/gen-erator will not only save energy, but it maygive away with the alternator completely.

J. Target 8 The integrator starter/alternatoron HEV

Combined ICE and electric traction, especial-ly in urban driving, saves up to 50% of the fuelconsumption (4.8l /100 km for Toyota Prius 4for 3000 USD additional equipment).There are quite a few topologies for HEV(parallel, series, combined) and Fig. 10ashows a belt integrated starter/alternator for aparallel HEV ( in parallel hybrids the ICE isde-rated, which explains some of the fuel sav-ings also). Fig. 10b illustrates the motor andgenerator torque requirements versus speed.

Figure 10 (a) Belt integrated starter/alterna-tor on parallel HEV (b) typical torque/speed

limit curves for a small carFinally, a review of HEV based on ToyotaPrius and Ford Escape is shown in Fig. 11.

Figure 11 HEV reviewNote on electric vehiclesThe ultimate goal is the battery or fuel-cellelectric (automobile) but, 100 years afterFord's first electric automobile, the limitedrange and the high costs of fuel-cells still ham-pers the electric vehicle mass utilization. K. ConclusionsAutomobile electrification:- serves to save fuel (energy), reduce pollu-tion, increase safety and comfort;- it is already well under way and here to stay - there are still many challenges ahead - a most likely 2020 automobile hybridizationis shown below in the table:

1. S.A. Nasar, L. Unnewehr, "Electric vehicle technology", New York, Wiley, 1982, 1981, 256 p. 2. Yimin Gao, Mehrdad Ehsani,"A Torque and Speed Coupling Hybrid Drivetrain -Architecture, Control, and Simulation", IEEE Transactions on Power Electronics, vol. 21, no.3, May 20063. A. Emadi(editor), "Handbook of automotive power electronics and motor drive", bookTaylor and Francis, Florida , 20054. I. Boldea, S.A. Nasar, "Electric Drives", Second Edition, book Taylor and Francis, Florida, 2005 5. Qiu, Y.H. Parlikar, T.A. Chang, W.S. Seeman, M.D. Keim, T.A. Perreault, D.J. Kassakian,J.G., "Design and experimental evaluation of an electromechanical engine valve drive", IEEE-PESC 2004, Aachen, Germany, pp.4838-4843

6. C. Bernez, X. Mininger, H. Ben Ahmed, M. Gabsi, M. Lecrivain, E. Gimet, E.Sedda, "High-acceleration linear drives: Application to electromagnetic valves", International Journal ofElectrical Engineering in Transportation, vol 1, no.1, 2005, pp 27-407. I. Boldea, S.A. Nasar, "Linear electric actuators and generators", book, Cambridge UniversityPress, 19978. Ion Boldea,Cristian Ilie Pitic, Cristian Lascu, Gheorghe-Daniel Andreescu, Lucian Tutelea,Frede Blaabjerg, Per Sandholdt, "DTFC-SVM Motion-Sensorless Control of a PM-AssistedReluctance Synchronous Machine as Starter-Alternator for Hybrid Electric Vehicles", IEEETransactions on Power Electronics, vol 21, no. 3 , may 2006, pg 711-719

References

14-V 42-V Micro Mild Full

HEV HEV HEV

Baseline 0% 33% 58% 6% 3%

Easy Street 0% 32% 57% 7% 4%

Rough Ride 0% 5% 37% 46% 11%

Comisia de Terminologie pentru ªtiinþele Exacte a Academiei României ºi-a propusca unul din principalele sale obiective sã fie editarea de dicþionare multilingve, caresã contribuie la stabilirea unei terminologii corecte în domeniul ºtiinþelor exacte.Având în vedere dimensiunile unei astfel de lucrãri s-a decis realizarea ei în etapeºi pe diferite domenii, începându-se cu domeniul ºtiinþelor tehnice. Dicþionarul Explicativ pentru ªtiinþã ºi Tehnologie - Transporturi Rutiere a apãrutîntr-un prim volum (literele A-K) ce se referã la terminologia domeniului autove-hiculelor rutiere ºi este realizat pe baza fondului terminologic standardizat peplan mondial. La elaborarea acestuia s-au avut în vedere câteva principii de bazã:s-a dat o deosebitã importanþã definiþiilor conceptelor, astfel încât acestea sã fieclare ºi exacte; s-a urmãrit ca relaþiile dintre concepte sã corespundã unei ie-rarhizãri, având la bazã tezaurizarea terminologiei din domeniul respectiv; atâtla stabilirea termenilor, cât ºi la elaborarea definiþiilor s-au avut în vedere celemai reprezentative ºi recente documentaþii elaborate de organisme naþionale ºiinternaþionale competente în respectivele domenii.Întrucât, aºa dupã cum s-a arãtat mai sus, prezenta lucrare se încadreazãîntr-o serie de dicþionare elaborate pe diferite domenii, s-a considerat ca,pentru evitarea unor suprapuneri, sã fie prezentaþi termenii specifici autove-hiculelor rutiere, iar dintre cei aparþinând ºtiinþelor fundamentale (mate-maticã, fizicã, chimie) sau celor tehnice generale (rezistenþa materialelor,organe de maºini, electrotehnicã, electronicã, termotehnicã, informaticã) sãfie abordaþi doar cei mai importanþi ºi intim legaþi de ingineria autove-hiculelor.Dicþionarul se adreseazã specialiºtilor din mai multe domenii aferente ingineriei autove-hiculelor: cercetare, dezvoltare ºi realizare de autovehicule, mentenanþã, asigurãri, organizarea traficului ºitransportului rutier, definirea regulamentelor tehnice privind automobilul ºi urmãrirea respectãrii lor, învãþãmânt tehnic mediu ºisuperior.

Autorii lucrãrii au pus accentul pe cercetãrile experimentale în studiul dinamiciiautovehiculelor, profitând de existenþa traductoarelor ºi elementelor de execuþieîncorporate, a calculatorului de bord ºi a unui soft, Matlab, ideal pentru domeni-ul tehnico-ingineresc, realizând o tratare sistemicã, interdisciplinarã, luându-seîn considerare atât influenþa terenului, cât ºi acþiunea conducãtorului auto.- Se abordeazã în mod unitar dinamica autovehiculelor cu roþi ºi cu ºenile,echipate cu motoare cu aprindere cu scânteie ºi cu aprindere prin comprimare- Se utilizeazã concepte ºi algoritmi specifici identificãrii sistemelor, pentru sta-bilirea modelelor matematice pornind de la datele experimentale- Se trateazã probleme care nu sunt abordate în literatura de specialitate dindomeniul autovehiculelor, dar care aparþin de dinamica sistemelor de oricetip: analiza dispersionalã, analiza de sensibilitate, analiza de corelaþie, analizade coerenþã, analiza în frecvenþã bispectralã, analiza în timp-frecvenþã, eco-dinamicitatea autovehiculelor, analiza robustã, dinamica spectralã, regresii,reþele neuronale, algoritmi genetici, mulþimi fuzzy, algoritmi neuro-fuzzy,tehnici bootstrap, statisticã bayesianã, curbe principale.Lucrarea este organizatã pe urmãtoarele capitole: 1. Elemente de bazã din teoria sistemelor 2. Cercetãri experimentale 3. Analiza în timp a datelor experimentale 4. Analiza în frecvenþã a datelor experimentale 5. Analiza în timp-frecvenþã a datelor experimentale 6. Dinamica liniarã a autovehiculelor 7. Dinamica neliniarã a autovehiculelor

8. Dinamica ºi economicitatea autovehiculelor 9. Analiza robustã a dinamicii autovehiculelor.