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Internal

Combustion Engines

Presentation Topic-Multi Point Fuel Injection

(MPFI) Presented To-Asst. Prof.O.P.a!a"

#ept. of Mec$.Engg.

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resented By-. %aura" umar ***+,

. %i!!$ant Mo$an ***+,,

. /ib$or %$arma ***+,++

. /ib$u ranjan ***+,+

. /i2as$ umar ***+,0

. /is$al Agar3al ***+,4

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Intro!uction

  Air an! fuel are supplie! to an I.C.Engine 3$eree5ot$ermic reactions ta2e place insi!e t$ecombustion c$amber an! t$e $eat energ' iscon"erte! into useful 3or2.

  To pro!uce energ' insi!e t$e engine 6 air fuelmi5ture is to be burnt in correct amount. Formi5ing t$e air an! fuel in correct range !i7erent

!e"ices are use!.  T$e preparation of a $omogeneous mi5ture of air-

fuel "apour mi5ture re8uires atomisation of li8ui!fuel !roplets an! mi5ing t$e 9nel' !i"i!e! fuel

particles 3it$ air. T$e atomisation is accomplis$e!b s ra in t$e li ui! fuel t$rou $ a no::le into a

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Carburetor

  Petrol "e$icles use !e"ice calle! carburetorfor suppl'ing t$e air fuel mi5ture in correctratio to c'lin!ers in all rpm ranges. !ue to

construction of t$e carburetor is relati"el'simple6 it $as been use! almost e5clusi"el' ongasoline engines in t$e past.

  T$ese !a's in place of t$e carburetor6 t$e

MPFI (multi point fuel injection) s'stem is use!6assuring proper air fuel ratio to t$e engine b'electricall' injecting fuel in accor!ance 3it$"arious !ri"ing con!itions.

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Fuel Atomisation

  During fuelling of a cylinder the fuel is

pressurised which causes the fuel to

become a vapour, allowing it to burn

easily (compared to the fuel being

delivered to the cylinder in liquid form)

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Fuel injection

   T$e primar' !i7erence bet3eencarburetors an! fuel injection is t$at fuelinjection atomi:es t$e fuel b' forcibl'pumping it t$roug$ a small no::le un!er$ig$ pressure6 3$ile a carburetor relieson suction create! b' inta2e air accelerate!t$roug$ a /enturi tube to !ra3 t$e fuel into

t$e airstream.  Mo!ern fuel injection s'stems are !esigne!

speci9call' for t$e t'pe of fuel being use!.

%ome s'stems are !esigne! for multiple

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Objectives Of FuelInjection System

  T$e injection s'stem of t$e compressionignition engine s$oul! ful9ll t$e follo3ingobjecti"es consistentl' an! precisel'<

. Meter t$e appropriate 8uantit' of fuel6 as!eman!e! b' t$e spee! of6 an! t$e loa! on6t$e engine at t$e gi"en time.

. #istribute t$e metere! fuel e8uall' amongc'lin!ers in a multi-c'lin!er engine.

,. Inject t$e fuel at t$e correct time (3it$respect to cran2 angle) in t$e c'cle.

0. Inject t$e fuel at t$e correct rate (per unittime or cran2 angle !egree).

1. =egin an! en! injection s$arpl' 3it$out!ribblin .

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  T$ere are t3o major !i"isions of Fuel

Injection s'stems< – Solid Injection systems6 3$ic$ inject

onl' t$e li8ui! fuel t$roug$ t$e injectors.

 –

Air Injection systems6 3$ic$ inject air

along 3it$ t$e li8ui! fuel

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VARIOUS INJECTION SYSTEM

MPFIsystem

Port injection

ThrottleBody injection

L-MPFI System

D-MPFISystem

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 Throttle Body Injection System

 T$e t$rottle bo!' injection (T=I) s'stem uses one ort3o injector "al"es mounte! in a t$rottle bo!'assembl'. T$e injectors spra' fuel into t$e top of t$et$rottle bo!' air $orn. T$e T=I fuel spra' mi5es 3it$ t$eair >o3ing t$roug$ t$e air $orn. T$e mi5ture is t$en

pulle! into t$e engine b' inta2e manifol! "acuum.

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 T$rottle =o!' Injection %'stem

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L & D PFI !asoline InjectionSystem

•  I-mpf system stan!s forIntelli"ent-ulti Point FuelInjection System 6 an!

• D-mpf system stan!s for Direct-ulti Point Fuel InjectionSystem$

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D-PFI !asolineInjection System

•  T$e #-MPFI s'stem is t$e manifol! fuel injections'stem . In t$is t'pe 6 t$e "acuum in t$e inta2emanifol! is 9rst sense! .In a!!ition t$e "olume of air issense! b' its !ensit' . As air enters into t$e inta2e

manifol! 6t$e manifol! pressure sensor !etects t$einta2e manifol! "acuum an! sen!s t$e information tot$e EC& . T$e spee! sensor also sen!s t$e informationabout t$e rpm of t$e engine to t$e EC& . T$e EC& inturn sen!s comman! to t$e injector to regulate t$e

amount of gasoline suppl' for injection . ?$en t$einjectors spra' fuel in t$e inta2e manifol! t$e gasolinemi5es 3it$ t$e air an! t$e mi5ture enters t$e c'lin!er.

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L & D PFI !asoline InjectionSystem

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INTRODUCTION

• MPFI- a tec$nolog' use! in petrol engines

• &ses a small computer to control t$e car@s

engine• In MPFI engine one fuel injector is installe!

near eac$ c'lin!er 6t$at is 3$' it is calle!multi point fuel injection.

• =efore MPFI s'stem6 t$ere 3as a tec$nolog'calle! B%arburetor .

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•  T$e computer in t$e MPFI s'stem!eci!es 3$at amount of fuel to inject

• %'stem also learns from t$e !ri"ers!ri"ing $abits

•

MPFI s'stem ma2es engine fuelecient .

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AI' %OPO'('TS OF PFI S)ST(

 T$is s'stem $as four major components t$e' are<

a) Air inta*e system

i. T$rottle bo!'

ii. I!le air control "al"e

b) Fuel delivery system

iii. Fuel pump

i". Pressure regulator s'stem

". Injector

c) (lectronic control system

"i. Engine Control Mo!ule (ECM)

"ii.On-=oar! !iagnostic s'stem

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Air inta*e system

  T$e air (correspon!ing to t$e t$rottle"al"e opening) is 9ltere! b' t$e aircleaner6 passes t$roug$ t$e t$rottle

bo!'6 an! is !istribute! b' t$e inta2emanifol! an! 9nall' !ra3n into eac$combustion c$amber. ?$en t$e lAC "al"eis opene! accor!ing to t$e signal from

ECM6 t$e air b'passes t$e t$rottle "al"et$roug$ b'pass passage an! is 9nall'!ra3n into t$e inta2e manifol!.

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Fuel delivery system

  T$e fuel in t$e fuel tan2 is pumpe! up b' t$efuel pump6 9ltere! b' fuel 9lter an! fe! un!erpressure to eac$ injector t$roug$ t$e !eli"er'Dpipe. As t$e fuel pressure applie! to t$e injector

is al3a's 2ept a certain amount $ig$er t$an t$epressure in t$e inta2e manifol! b' t$e fuelpressure regulator6 t$e fuel is injecte! into t$einta2e port of t$e c'lin!er $ea! 3$en t$e injector

opens accor!ing to t$e injection signal form ECM. T$e fuel relie"e! b' t$e fuel pressure regulatorreturn t$roug$ t$e fuel return to t$e fuel tan2.

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Injectors

 T$e opening of t$e injector is controlle! b' t$e "e$icles EC&

 T$e injector is supplie! 3it$ t$e batter' "oltage "ia a rela'6t$e eart$ circuit is controlle! b' t$e EC&

?$en t$e circuit is complete! b' t$e EC& a solenoi! operates6t$e injector "al"e opens6 fuel is t$en able to be spra'e! intot$e inlet manifol!

 T$e "al"e mo"es roug$l' .1-* millisecon!s. T$is is 2no3n aninjector !uration or opening time

 T$e EC& 3ill ma2e amen!ments to t$e !uration !epen!ing onengine temperature6 loa!ing air temperature an! batter'

"oltage

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T+e role of t+e Injectors

  The injector delivers a finely atomized spray of fuel

into the inlet port

  The injectors also vary the amount of fuel delivered to

suit the engines conditions

 

The spray is obtained by passing fuel (that is

pressurised) through the nozzle of the injector

It is located in the inlet manifold near the cylinder

head intae port

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Ty,es of injectors

$ Pintle Ty,e Injector -O7ers goo!atomi:ation of fuel.

  Prone to !eposit buil! up on t$e Pintle

"al"e (!eposits can re!uce t$e amount offuel >o36 an! t$erefore t$e "e$icle 3illrun leaner t$an recommen!e!.

. .ole ty,e injector - Fuel is !eli"ere!t$roug$ $oles !rille! in a !irector plate att$e injector tip.

  O7ers goo! fuel atomi:ation an! gi"es

better resistance to !eposit buil!-up.

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•  T$e injector isplace! on t$e si!eof t$e inta2e

manifol! near t$einta2e port

•

E"er' c'lin!er ispro"i!e! 3it$ aninjector in itsinta2e manifol! .

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 (lectronic controlsystem

  T$e electronic control s'stem consist of "arioussensors 3$ic$ !etect t$e state o engine an!!ri"ing con!itions6 ECM 3$ic$ controls "arious!e"ices accor!ing to the signals from t$e sensors

an! /arious controlle! !e"ices. T$e s'stems are  Fuel injection control

s'stem

 I!le spee! control s'stem

 Fuel pump control s'stem6

 Ignition control s'stem6

 a!iator fan control s'stem6

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 (lectronic control /nit0sc+i,

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?OIG

• Injection no::le atomi:es fuel into "er'small !roplets.

• Ac$ie"e! b' pro"i!ing loa!e! "al"e nee!le

forcing out fuel t$roug$ small ori9ce.• o::le "al"e seats on conical seating !ue

to spring pressure on spin!le.

• %pring pressure is suitabl' a!juste! b'a!justing scre3 to gi"e correct openingpressure to fuel.

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• Fuel enters to passage !rille! in no::le $ol!eran! >o3s to an annular groo"e aroun! nee!leseat.

•  T$e nee!le (no::le) "al"e is t$en lifte! againstspring pressure to allo3 $ig$ pressure fuel to>o3 into combustion c$amber.

• o::le "al"e closes 3$en fuel pressurebecomes less t$an spin!le spring pressure.

• E5tra fuel going up to no::le spin!le is carrie!

a3a' t$roug$ lea2-o7 pipe to fuel tan2.

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FUNDAMENTALS OF FUELINJECTION

• MPFI %'stems can eit$er be<

• %e8uential

• %imultaneous

• Group

•  T$ese tec$ni8ues result in better Hpo3erbalance@ amongst t$e c'lin!ers6 $ig$eroutput from eac$ one of t$em6 along 3it$

faster t$rottle response .

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 T'pes of MPFI %'stems

• %imultaneous injectors 3ill operateall (or groups of injectors) at t$e

same time• %e8uential 3ill operate

in!epen!entl' an! open an! close at!i7erent times (!etermine! b' t$eEC&)

• Group use! in c'lin!er pairs in /-series enginesJ

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• D%e8uentialD is t$e best from t$e abo"econsi!erations of po3er balanceKoutput

•

B%e9@@-%e8uential Electronic FuelInjection - tec$nicall' is t$e best of t$eabo"e "ariants of MPFI

•  T$e Hon-boar!@ EC& primaril' controlst$e Ignition Timing an! 8uantit' of fuelto be injecte! $

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AD1A'TA!(S of PFI. Impro"e! fuel consumption

. =etter for t$e en"ironment

,. =etter performance.

0. Imme!iate response6 in case of su!!en acceleration K

!eceleration.

1. o nee! to cran2 t$e engine t3ice or t$rice in case of

col! starting as $appens in t$e carburetor s'stem.

+. More uniform AKF mi5ture 3ill be supplie! to eac$ c'lin!erL

$ence t$e !i7erence in po3er !e"elope! in eac$ c'lin!er

is minimum. /ibration from t$e engine e8uippe! 3it$ t$is

s'stem is less6 !ue to t$is t$e life of engine components is

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 T$an2- ou