8/11/2019 Extreme Downsizing by the Two

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DOWNSIZING AO EXTREMO PELO

MOTOR DE DOIS CILINDROS A

GASOLINA DA FIATO novo motor de dois cilindros de 0.9 I a gasolina com turbocompressor representa um marco no

desenvolvimento de motores da Fiat Powertrain Technologies. O ento chamado motor Twinair um excelente

exemplo de downsiing ao extremo! no somente o deslocamento total mas tambm o n"mero total de cilindros

esto limitados. #ra$as ao turbocharging e a ado$o da tecnologia %ultiair& per'ormances excelentes soatingidas& igualando em (0) a dos motores *+ ,*o +spirados- com maior deslocamento& enuanto melhora a

economia de combust/vel em pelo menos (). */veis de emisso atendem as atuais normas do 1uro (

enuanto o sistema total protegido por pacote para atingir as 'uturas normas do 1uro 2. #ra$as as otimia$3es

gerais 'oi poss/vel estabelecer novos padr3es de *45 para motores peuenos.

MENOR CONSUMO E MAIOR DIVERSO DEVIDO

AO DOWNSIZING

Fiat sempre foi muito forte no segmento de

carros A e B. A chave para este sucesso est

no design e flexibilidade desses veculos, e na

confiabilidade, performance e economia no

consumo de combustvel de seus motores.

The increasing demand of fuel consumption

reduction and more "fun lo drive" can be

satisfied with the downsiing concept as well

as new more efficient engine architecture.

Fiat !owertrain Technologies F#$T% decided

to develop a new engine famil& to full&

compl& with the upcoming mar'et demand (

)(. This new engine famil& had to cover a

power range from *+ to '- focusing onurban cars, mainl& A segment, with the

possibilit& of use in B segment for high

downsiing and premium fuel consumption.

Three main configurations were identified

naturall& aspirated, turbocharged with /0.1

and '-% and a 234 turbocharged

version. All of these engines had to share the

ma5orit& of the components in order to be as

industriall& efficient as possible.

it& identified a displacement around 6.7 )

as the best compromise. The second step

design was the architectural definition of

the engine number of c&linder, bore, stro'e,

etc%. Fuel consumption, cost, 389 and

performance were the main drivers. Two:,

three: and four:c&linder architectures were

compared regarding thermod&namic effi:

cienc& and friction, As is shown in ; the

two:c&linder configuration shows the best

thermod&namic efficienc& than's to a con:

venient c&linder displacement. Two:c&l:

inder architecture also offers longitudinal

length and weight advantages< engine

length advantage ma'e the two:c&linder

engine more suitable for h&bridiation.

389 behaviour of a two:c&linder configu:ration could be a potential issue the use of

a balance s&stem for the first order free

forces is a must< the remaining 0n=order

free forces are even lower with respect to a

four:c&linder engine, 6. The twin con:

figuration 6> to ?/6> cran' design% was

preferred to the 6> to )+6> cran'shaft la&:

out mainl& due to the e@ual spacing of the

combustion that generates a first order dom:

inant tor@ue irregularit& instead of the spuri:

ous half orders of the second architecture.

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is Plat'orm %anager 'or the iwinair

1ngines Plat'orm at Fiat Powertrain

Technologies 8.p.+. in Tu: I la .

;+%I+*O %I-.

1*#I*1 +7linder engine displ. Ill

9 Thermod>namic e''icienc> versus

engine architectureFourAc>linder engine displ. Ill

Optimal one

ATZ autotechnolog> 0CC0CC 4olume CC

tion on the cran'case. The benefit is a re:

duction of vibration on the engine suspen:

sion brac'et. The chain la&out was opti:

mised to gain low friction and the chainvane is closed b& a frontal aluminium cover

that ensures good ventilation within the

engine. The water pump is integrated in the

front cover and directl& driven b& the

balance shaft with benefits on friction no

hub load from belts%. This results in the

front engine side being ver& compact and a

chain drive s&stem for life that re@uires no

maintenance. For the engine bloc', cast

iron was preferred to aluminium as the best

compromise between costs, weight, robust:

ness and 389. #ntegration has been a

driver for the design and all piping to oilfilter and cooler and water b&pass were

integrated in the cran'case casting itself

thus reducing piping costs, and eliminating

fixations and lea'age danger. The 234

version was ta'en into account from the

beginning of the pro5ect. This is a bi:fuel

engine gasoline and 234% with no per:

formance reduction passing from gasoline

to 234 fuel. The sharing of most of the

components for all the engines of course

has a positive impact on cost and invest:

ment. The drawbac' is thai the design of

each part cran'shaft, conrods, cran'case,

cooling s&stem, etc% has been done ta'ing

into account the envelope of the re@uire:

ments of all the engines of the famil&.

F6D 4+7I+E1 4+41 8D8T1%

ultiair technolog& appeared on the mar:

'et for the first time on the so called Fire

engine in 0667 0C. F!T invented and pa:

tented this technolog& it is a full& variable

control valve s&stem that uses an electro:

h&draulic actuator so called Dniairactuator owned b& #3A Echaeffler% and a

group of dedicated controls strategies to

allow improved engine efficienc& ?C. A

new electronic control unit developed b&

agneti arelli% integrates engine and

ultiair module control. ultiair uses all

capabilities offered b& the Dniair actuator

to manage the engine inta'e valves stro'e:

b&:stro'e and c&linder:b&:c&linder. The

main benefits arising from this full control

are fuel consumption, than's to pumping

losses reduction, and performance than's

to volumetric efficienc& optimiation. ;therbenefits come from the @uic' response

stro'e b& stro'e%, internal 4G manage:

ment, etc, H. For F!T it was clear from the

=ournal diameters and piston weight were

reduced to minimie cran'train friction.

The piston rings tension has been signi:

ficantl& reduced than's to the adoption of

a dumm& head for c&linder honing it

decreases the *th

order bore deformation%.Iifferent balancing s&stem la&outs were

designed and tested final configuration

consisted of a balance shaft installed into

the cran'case driven b& a couple of gears.

Two roller bearings where preferred to plane

supports to reduce impact on engine friction.

The position of the balance shaft has been

optimied to reduce the l1)order tor@ue

fluctuation on the cran'case. #n fact, thebalance shaft generates also a sinusoidal

moment that has been tuned to be in

opposition to the combustion tor@ue reac:

temperatures at -;T. 2ompression ratio

was set at )6.6. This allowed reaching the

re@uired full load performances while

offering an excellent base for good part:

load fuel econom&. The positive s&nergic

effect of the ultiair s&stem and the turbo:

charger on low end tor@ue is shown in H.

2ompared to an engine with fixed valve

beginning that the new two:c&linder engine

should include Aultiair technolog& tomaximie the fuel consumption reduction

and performance.

;141OP%1*T T+7#1T8

For the first engine variant, the following

targets were defined

/0.1 '- power J 1166 rpm and

)11 3m .tor@ue J 0666 rpm best in

class fun to drive of all 6,7 to

).* ) gasoline vehicles 389

which is e@uivalent to bestfour:c&linder in line engines

much less than )66 g 260K'm on

3I2 benchmar' in the class from

6.7 to ).* ) gasoline vehicles .

durabilit& of 066,666 'm 0* months

development time from

"pro5ect approval to engine E;!. The

fnain characteristics of the engine are

given in ;.

P17FO7%+* specialiing in

development o' test bed

drive trains o''ers optimal

solutions 'or testing

electric and h>brid

powertrains. tuned

highl> elastic test bed

drive sha't.

the acoustic power contribution of each

engine part are shown. Euch detailed anal&ses

guided the choice of the components suitable

for the acoustic optimiation. #n this wa& all

the components, responsible for the noise

radiation, have been improved, such as

c&linder head cover, chain cover and oil pan,

pulle&, etc.

Based on the results of the tests the most

important noise sources have been identified

both at idle and during speed sweep wide

open throttle -;T%. !arallel to numerical

simulation, an experimental panel

contribution intensimetr& techni@ue% of the

radiated noise in an ane:choic chamber has

been performed. Both act ivi ti es allowed

detecting and optimising all the radiation

sources ensuring a good sound level and

@ualit&. Tor@ue fluctuation is characteried

mainl& b& lsl

order, instead of the t&pical 0$")

order of the four:c&linder engine, generating

a different interaction with the transmission

generating a shifting of the resonances at

higher engine speeds. The t&pical speed

ranges, on which gear rattle could be more

critical, are then shifted at higher speeds

letting this phenomena coming even less

relevant respect to a four:c&linder engine.

Further improvements were made to the

exhaust s&stem to control the noise level,

enhancing the engine characteristic sound.

an& tests were carried out in order to assess

the number and the volume of silencers andthe effect of resonators. The control o the

right timing of valve opening and closing,

trough the ultiair s&stem, has been

placemenN engine running often at high

loads, is the possibilit& of controlling the

effective compression ratio using the Aulti:

air s&stem. ;n a turbocharged engine

above approximatel& 16 L of maximum

load it is necessar& to dela& ignition timing

with respect to the ideal BT, minimum

spar' advance for best tor@ue% values due

to 'noc'ing, The ultiair s&stem, when

used in the late closing mode, allows con:

trol of the effective compression ratio real:

ising the At'inson:iller t&pe c&cle. 2om:

pared to cam phasing the advantage is that

the start of the inta'e phase is maintained

at the ideal moment. This is reflected b&

the BEF2 values of ?1 gK'-h at the 0666

rpm : 0 bar B! point and the minimum

fuel consumption in the map of 0*0

gK'-h. Both values are benchmar' for

turbo%charged engines below ).* ).

+n elastic coupling with

nonAlinear sti''ness and

high damping behavior.

1speciall> advantageousis the adGustable sti''ness.

%anual docHing s>stem

'or eas> docHing o' drive

sha'ts to the test bed.

*45 OPTI%I+TIO*

The main tas' of the 389 engineering

was to optimie the sound radiation in

terms of level and @ualit&. This 389 per:

formance has been achieved b& using

state of the art 2A simulations which

allowed an acoustical optimiation of the

single components installed on the

engine. Therefore, a numerical F ulti:

bod& and B methodolog& was applied

with experimental support for the target

definition, in order to predict the compo:

nent normal modes that have most effect

on the sound radiation and to give sup:

port to identif& the modification$s areas.

#n H the calculated surface velocit& and

+utomatic docHing

s>stem especiall>

developed 'or pallet

s>stems.

the 'e& point. The result of the calcula:

tion and test activit& has been one big

centrall& mounted silencer halfwa& the

exhaust line and a resonator ver& close to

the exit of the s&stem.

Iuring the 389 development, the

ultiair technolog& pla&ed a particular

role also in reducing the vibration of the

powertrain in idle condition< in fact,

than's to the higher combustion stabilit&

obtained b& .this technolog& and the bal:

ance shaft, the powertrain vibration

amplitude is ver& similar to a four:c&lin:

der engine. The result of this activit&made the Twinair a reference for this

performance in his engine class.

1*#I*1 I*T1#7+TIO* O*