Bosch KE-Jetronic manual

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BOSCH
Electronically Controlled
Gasoline Fuel-Injection System with
Lambda Closed-Loop Control
KE-Jetronic
The things an automobile
has to go through ...
--
"!I> .•
If
KE-Jetronic
A gasoline injection system must inject
precisely th e correct amount of fuel for th e
various operating condi tions. Whereas the
increase in engine power was the main object
at the start of development work on gasoline
injection, today we are spurred on by the
necessity to improve the fuel-consumption
figures and to reduce the toxic emissions in
th e exhaust gas to as Iowa level as possible.
The purely mechanical systems are not able
to fulfi ll these stringent requi rements. For this
reason, the we ll-proven K-Jetro nic was
retained as the basic injection system but
was uprated to a more intelligent and more
efficient system by the addition of electronic
ci rcui try.
This synthesis, comprising the mechanical
basi c fun ctions coupled wi th electronic adaptation and opti mization funct ions, is the
KE-Jetronic.
The spark'lgnltion engine
The 4' $troke principle
FueL management
Fuel' management syetems
The KE·Jetronic fuel'injection
system
System ove rview . advantages of the
j(E·Jel ron ic
B;>sic fun<;:tlons
Fuel supply
Fuct rnl)tering
,
,
,
Mixture adaptation
Basic mi , ture adaptation
EIec1rOmC control un it (EeU)
Electro -hydraulic pressure actuator
Cold' start, w arm·up. acceleration.
fu ll·load. id le
"
SuppLementary functions
Overrun fuel cut·off
Engine·speed limiting
Mi , ture adaptation at high alt itudes
"
Clean emissions
Cata lytic altert",atment
La mbda closed·loop C<lntrol
"
Electrical circu itry
"
The front cover shows t~ mi,ture-control
un it together ...,th the air·ll".. sensor.
inleg,al fuel distributor. cleclro'hyd raulic
pressure actualor. and alec\tonic conlrol
unit (EeU).
," I
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The Spark-Ignition Engine
The spark-ignition engine, The 4-stroke cycle in detail
also known as the Otto1 at st roke: intake
cycle engine"), is an
2nd Slroke: compression
engine with externally
3rd stroke: combustion (power)
4th st.ch: exhaust
supplied ignition that
Control 01 the gas cyde in a 4'S!foke
converts th e energy
spark·ignition engine is by means 01
contained in the fuel into valves whiCh open the inta ke and exhaust
passages in aCCOfdance with the camwork.
shafl positiot'l.
In the spark·ignition engine. a fuel·induelion system OIJtsidelhe combustion chamber forms an ai,·fuel mi,'ure. This mi.ture,
drawn in bythepiston'sdownward (intake)
stroke. Hows into the combustion chamber. During the upward (compression)
stroke 01 the piston this mi>1ure is com-
pressed. and timed e"mnat ignition froma
spark plug initiales il8 combu8lion. The
heal energy released by this combustion
Intake stroke
Intah val ve: open
Erhaust valve: closed
Piston movement: downward
Combustion: none
As it moves downwa.d. the piSlon
enlarges the cylinder volume and draws in
Iresh air·fuel milrture through the open
intake val ve.
increases the com pressed gu's pressure, and it is this combustion pressure
which delivers the mechanica l work
through the piston and the crankshalt
when the piston islorced downward again Piston movement upwa.d
during its combustion (pow",) stroke.
Combustion: init ial phase (igni1l0n)
AUer each combustion (power) stroke, the As it moveS upward. the piston reduces
piston again reverseS itsdirectionand dur' the cylinder volume and comp.esses the
ing its upward (exhaust) sHoke lorces oot ai.·luel mi.ture, The compression 'atio is
the burr>ed gase •. The 4'5troke cycle has in the o.der of belween 8:1 and 12: 1
nOw been compteted, and begins again depending upon engine design. The high·
when the piston draws a Iresh charge 01 er the compression. the htgher the engi.
air·luel mi.ture into the combustion cham· ne's thermal ellic iency and the bette. Ihe
ber during its ne. t downward (intake) fuel is ut ilized. The compression ratio is
stroke. In motor vehicles, the gas cycle limited by Iheengir.e·soctane requirement
takes place predominantly using the 4· (knocking limit). Knocking is the irregular,
stroke cycle described above: one cycle uncont rolled combustion of the ignited
taking place every two reVOlutions 01 the mi.w.eaccompanied by a la.ge p.essure
increase. Knock leads to engine damage.
crankshaft.
By means of unifo.m air-fuel mi.tu.e distri bution in the cylinder. and utilization of the
How effects in the intake passage. as
,) WI: Se<'_ ,,,,",,ph ~ .pa,k·ignir.on - "9'.lille<i wi'hKE-J.."", .. (PhOlO' 0 •• ",1,,,·&,"' IIG). well ss appropriale combuslion-chamber
~I IIbtkf"~
..tok•• oflh _ 4 ..1""".
r . l"r#~
design. the knocking limitcan be shiltedto
permit higher ma. imum compression
.alios. Just be/ore the piston .eaches TOC.
the spark plug igniles the compressed ai.·
fuel mixtu.e and initiates Ihe combusti on.
Combustlon(powerl stroke
Intake ~alve: closed
E>haust valve: closed
Piston motion: downward
Combustion: burn·through phase
Aller the spark plug has ignited the com·
pressed ai, -fuel mi.ture. the tempe rature
and Ihe p.essure increase rapidly. The
pressu.e drives the piston downwa.d. and
delivers wo.k to the crankshalt by way 01
the connecting rod. Thiswork is available
as angiM power output. Power inc.eases
along with increasing engine speed, and
for this ruson it is necessary 10 usea gea.·
box 10 efficiently malch the engine speed
to Ihe vehicle speed ,
Exhaust s troke
Intake ~a lye: closed
E>haust valve: open
Piston motion: upward
Combustion: none
Moving upward. Ihe piston forces out the
burned (exhaust) gaseslhrough the open
",,!\aust valve . After Ih is fourth stroke, the
cycle starts again. In practice, the valves'
opening times overlap somewhat in order
10 utilize gas flow and hydrodynamic pul·
salionslor bettf)fcharging and purging of
the cylinde.,
' ) Named afte. Nikolaus Augusl Otto,
t 832·1891. Otto showed the lirst gas
engine with compression operating
according 10 the 4 ·stroke princip1e at the
1878 Paris World's Fair_
"" rl< ';II~;1io>r ." ~in e,
2. Compr . ..1OJI
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Fu el manage ment
Air·fu e l mixture
I.hL-§Rid'Jg!.!ilil!!l.....ngine requires s
JPocific air·luel ratio for its olleration. The
tbeorelical air·luel ratio;, 14 7·t Co",!.,.
lion of Ihe aiduef ratio is required for lhe
~R!!Ul!!!g cpnd·tions.
The specific fuel consumption 01 a spark·
ignition engine IS dependent princIpally
u~n theair·fuel ratio. Theoretically. fortull
combustion and Iberefore mInimum fuel
consumption. Ihe greatesl poss,ble
amounl of e.cns air would be desirable:
but fo, ,easons 01 liammabihly and Ihe
limite<:! lime available for combustion. this
is not possible. Fo,contem~raryengines,
ma. imum luel economy occurs al an air·
fuel .atioolapp,o.imately 15 ... 18 kgairto
1 kg luel. In other words, some 10,000
lit .. ,s of air are neces8arylo. Ihecombus'
lion 01 1 lite, of fuel. The chemical mini·
mum for complete combustion is I"rmoo
Ihe Slo,ch,omelric rati", and '5 14.7:1.
Because ""hicle engines are ope.aled
mOSI of the lime at pan load. tbey are
designed 10. maximum fuel economy in
Ibis range. For Iheother operating condi·
lions. such as idle and full load, mi.lu.es
are called lor Ihat a,e ,icher in luel. The
!uel·managemenl sySlem must be able 10
meet Ihese varying requirements.
theoret'cal a" requ"ement
).K 1
Theaclual inducled aor quanlity equals Ihe
theoretical air l'<K1ui.emenl.
;'<1
Shortage 01 aor, or mixture 100 riCh.
inc'casoo power at ~ . 0.85 ... 0 .95.
,,,
Excess air, a. lean minure at I. ..
1 .05 ... 1.3. reduced fuel consumption and
,e<:!uced powe,.
~> 1.3
The mixtu.e will r>O longe. ignite, the mis·
I"e limit has been e.eceded.
I. " 0.95 ... 0.65
Spark·ignitionengines develop the" rna';'
mum power al 5 ... 15% ai, shortage.
), .. 1.1... 1.2
Ma.imum luel eCOr>Omy ocCurS at about
20% e.cess air.
A appro •. 1.0
Perleel ,die ope<ation at sioichiometric
ratio.
i. " 0 .85 ... 0.75
Air ratio
Good Iransilionsal15 ... 25%airshorlage.
To ind icate how la, the aClual air·luel raho 'Transition" is defined as Ihe change I,om
deviates from Ihe theo,elica l (14.7:1). Ihe agi.en load range 108nothe,. For instance,
ai, ralio, denoted by the Greek lener from idle to part a. !ullioad. Good t,an , i·
), (lambda) has been chosen:
lion is usually synonymous with good
acceleration.
The illustral>ons show the dependenceo!
power. specific !uel consumption. and pol.
lutants emission on the air ,alio. As can be
seen. the.e is no single optimum air 'alioa!
which all factors are ideal .
i.
~ 0.9 ... 1.1
In p.actice, ai, .altosol A .. 0.9 .. 1.1 have
proved 10 be Ibe most p,aclical.
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SloicM""",lrie.i, -/.w ,. u<> lor !<lui
a.>mb vsti<><>.
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10.000/""
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4) 'n"~.M1l 01 ,he ./, ... /10 (,J
011_' (P) .nd
eon"'",pli<><> (1;,).
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Fuel-Management
Systems
~g~.iW!li.whethgrolthe
Cilrburetor or lueHn~~~
tu!Lo!..~g..J.!lt..Mlt:possibl o
lue! mi.lure lor the panjcular
cond'liRIIs of th!tengiM.
ai ..
o~g
ThecBrburetorottha luel·injecti onsystem
prepareS the air-fuel mi. ture lor t~e spark·
ign ition engine. Du ring Ihe lasl lew years,
Ihe Irend has become st[('"gar towards
manifold lue(.injection. T~,s !tend '5 supported by the advantages oHerod by l uel
injection in connection witll the demands
lor economy. efliciency, excelfent drive'
abil ity. and low-pollution ,.~aust gas.
ThereaSons lorthesa advantages fiein the
fact thai manifold injection p<l'tmits exlre·
mely precise metering ol the fuet as a fac·
tor ol the operating and load ing condit ions
of the engine. white at the same time tak·
ing environmental condid .. fations into
account. In the process, Ille composition
of the mixture is contrclle<! so precisely
Ihat the pollulant level in the "haust gas
remainSlaw.Fu rlhermore. theallocation 01
an injectian va lve la each cylinder results
rn rmprave<! d,stribution al the mi.ture.
Since the carbu retor can be dispense<!
with. this means that the induction paths
Can be designe<! to achieve the best·pos·
sible charging 01 the cylinder with air-IYel
mixture. This leads toa higher torque.
Co mb i ned mechanlcal ·e lectron lc
lu eH nj ectio n s yste m
The basic mechanical system from Ihe
K-Jetronic serves as tho basis lOt Iha
KE· Jelronic. Due 10 the "'tended processing of operational daiS, electronically
controHed au.il iary functions w<)re inoo.·
porated 10 adapt Ihe injected luel quantity
ta Iha various eng ine opera~ng condi·
tions.
Electronic luel·ln jectlo n s ystem s
The L· Jetronic aod ilSvariants are electro·
nically controlled fuel ·injection systems
Solenoid'operSle<! inject ian val vas meter
the luel intermittently to the intake ports.
The system is described in t~ booklet
"L' Jetronic' in Iha Bosch Technical
InstruC lion series.
Co mb ine d Ig n itio n system an d lu el I njec tion s yst em " Molfo nlc"
Gaspjir;e injection systems can only pro·
vide the answers to someoithe prob lems.
In o.der to improve Ihe O."all combustion
process. Ihe ignition point must also be
adapted to the engine aperating condi·
tions. The Motfaniccamb ines the ignition
system and the luef.injection system. bOlh
01 whicharecontrolle<! bya si"glecomputer in accordance with common optimi~a'
tion cri teria. For mOre details. refer to the
booklet "Motronic' in Ihe Bosch Technical
Instruction series.
Advant age s o l luel lnjeclio n
• Increase<!luel economy
Mechanlcalluel-l njecllon s yste m s
W it~ a carburetor. or carburetors. Ihe ai .The K-Jetronic is today the most wide· luel mi>ture5 arriving at the individual
s!,read mechanical fuel-injection system . cyfinders are dillere nt due to the air-fuel
It req uires 0(1 drive, sod injects the l uel separation which OCCurS in the re.pective
co ntinuously. The K·Jetfonic .yslem is intake passages. By forming a mixture lhat
described in delail in Ihe hooklel provides even the most unfavorably local"K-Jelronic" in the BoSch Technical ed cylinder wit ~ sufficient fuel. the typical
carburetor meters too much fuel overall.
Instruction ser ies.
Aparl from this, during tead changes a film
olluel is deposited on the intake-passage
walls which is subsequent ly vaporiled
again. This leads 10 furl her unwanted
5) InWu. n • • ofthe ftIr r.'/o
• • /NIv.I"!iI.O "","po<iliGn.
fJJ
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6) POWfjf . nd 10"1". <""""$.
• _ wllh J. ,roNe. b _ wilh <...h
fh.
re""
... r----------------.-,'w
~
variations in lhe mi.ture. arriv,ng al t~e
cylinders. and I~ resull ,s e.cessive fuel
consumpt,on aod uneven cyfinder load·
ing. On the other hand. both the K- and
L·Jetron'c systems allocate an individual
injection valve to each cylinder.
These valves are cenlrally cont.olled. and
this enSures that all cyhnde.s are provided
wilh the same. precisely Controfle<! lue!
quantity at all times and under all condi·
tions. Nomoresnd no less than is absolu·
tely necessary.
• Highe, power autpul
Jetronic fue!·injectionsystems permitoplo'
mum ,ntake'passage design, and by virtue
01 the improved cylinde, fi lling this p.o·
vides higher lorque. Theove rall resu ltnre
hig~er specilic power output and a torque
curve which betler satisfies practical driv·
ing r~u""ments.
• Immediate throWe response
Jatronic syslems respond 10 chang ing
load cond,Ioons virtually without any lag at
all. because the injection va l.es inject the
fuel directly at Iha engine's intat<e valves.
• Improved cold slat! and warm·up
Due to Ihe prec ise melering of the luel in
accordance with the engine temperalure
and tha crankir>g speed. starling times arc
short and the run-up to idle speed
presents no problems.
Du~ng warm·up. the precise adaptat ionol
the injecte<!luef quantity re.ulls in smoolh
running and imme<!iate throllla response
along with minimum fuel consumption .
• Low e.haust emissions
The poflutant concenlrations in Ihe
exhaust gas are directly relaled to the airluel .aloO. II one wants 10 operate the
et1gine at tha minimum emissions point.
the luel-managemenl systom muSI be cap·
able of "aclly mainlaining the co"o,
sponding air·luel ,oti(l. The K· sod
I.·Jetronic systems are SO accurate that
they provide the predsion of mi!1ur" con·
trol whiCh is necessary ta comply with the
particular emission regulations.
- ..
1J Fuel ""nov"",d"". eomp..t."" b. I ..... n
Jof"'nic _nd COrbvreIQr·po'....d .n~ lne..
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The KE-Jetronic gasoline injection system
System overview
A mechanical I>ydfauhc '''teehon s,stem
p.ew,d.,.,II<!
lot the KE·JetronH; the
same as 11 dOGe lor I"e K·Jetron,c (see Ihe
publication "K·Jetton,c· ftom the Bosch
Technical In.lfuCloon ...,ies). The Siream
ba",
of ." df. wn ;n by t he eng. ne de/lee!o a """.
so. plate, which ,n lu,n controls Ihe luelmeu"'''11 plung .... DependIng upon ns
POSitIon. Ih,. plur.g8f open. Or closes Ihe
,,,e1-me,..,"9 IIIIL The ba"e function 01
the KE"-Jelronoc ,'10 rnelG'tlhe fuel 10 Ihe
""!I,ne dependent upon thequanh'y oIai,
d.awn in by lhe eng,ne!th" ma,n acluar'ng
vanable). aul in COflI.Ulto tho K- Jet •.,.."c.
the KE·jet'oroc 11110 uke$ • number of
add,tlONI .no""
data intO
account by mN'" 01 "nSOts. TI\e OUlpyt
.. 9""'1 from the, .. .ensor. are proceSleod
by an elOCiron,,; con1tol uM (ECU) which
eo<>I,oI1 an ellICtr<>hyd.auhc p'elIsure
acluato. whICh adapts th. ,nj<!(:led luel
quantity to the .arious operating condit"'ns.
tn ..."" of matiunction. Ihe KE·Jm,onic
OIler.tM solely w,th lhe buic function.
and Ihe d ..... Ihen has a system al ru.
d"llOsal wh,ch pro.,des good limp·home
... pab,h".. wh .. n the ongine i. warm.
""""'''ng
Advantages of t he
KE-Jetro ni c
l owor luef..::onlumpUon
With convont,OtIIIlluer'malll!}etnenl sys,
lem'. the dill'rencel ,n the lengths 01 th.
,ntate. pori. rllult ,n d,lI ..enl air·I"e! m,,'
IU<1l' II the ind,.id"al cylioderS. With the
KE·JO I,on,e. each eyhoder ,s allocaled itt
own I ueH nlo<:lIon valve wh,eh ,njects con·
t,nuilly onla the intake .al.o. The in!"Cted
fuel •• pari.e. Ind mi". inlensively wilh
the.or drawn in by the P'SIOn. Ttr;s mean.
tllal inadditionta the p,ec,aemelering. the
l"eI 'I ,.onlyd,,,,,b .. ,ed belween Ille ,od,·
vldu.1 eng,ne c)'hnd ..... Be'ng as Ihe
.nlak, man, fold. anly "",ve 10 ca,f}' the
,ntaMl .. r 10 Ihe c yhnd .. , .. the condensa'
toon of the luel on the ma n, fold walls. a ph,·
..-.enon ,n eClr'-'1oona1 systems whrch
",c.o._ the fuel cont"mpllOn. is pn..:t'·
...It)' ruled CIUI. The KE·Jetronrc systom
ent""a thalcon"derablyless lueI" uled
fNirtrcularty du,,"11 the w .. m·up phase.
du,,"11 ..,cel.... I'on enrrchment. at lull'
load. and dunng Overrun wilen ,I swilcheS
011 Ih .. luel lupply.
,
Rapi d a d . pt. llo n to o p e ra Unli
co ndi lions
The fuel reC!urrement dilfcrlgreally from
Ihe normal t.gu"tI during lhe poststan
per,od. dunng warm·up. and during acce.
le,at,Oll and lull·load. By means 01 com·
mand. recer~ from ,ta EeU.lhe KE·Jelrcnie into,ven" in Ihe proparalion oltho air·
f"el m.. t"re and increases or decreas"
th .. in)GCted IU'GI quant,ty aru;ordingly. The
KE·Jelronoc: syslem incorpooates addil>Or'lal
""nlOfl for the 'eg,strat,on of the ""g'''''
tempet'''"re. the throWe· ... I.e posrtron
(load IIgMI). and tM sensor·plale dellec·
t,on (QO".,.ponds .ppro~tely 10 the
cha""e ,n eng,ne poweo- 0'ttI, t,mel. Wilh
tho ard 01 theM .. _ .. II>e ECU com·
mand. the hydrl"hc pressur.. actuator 10
eo Iher "lean'OW the mi"ure or "richen' iIn
approprial ... The KE·Jetronic re&ponds
rap,dly I'"
,n eng"'o ope,at·
ing cond lt'o .... and ,mp'o.es lhe torq"e
che,aCler,IIic••1 well as Iho ong,ne lie .. ·
b,lrty, Th,. r'Su lll in d,'hnC I advantages
whan d" v, ngalene 'IIY ·al I,c,ont lowengina
speeds snd in I I high. gear as pOssible.
aod al.., in an improvement 01 driv...,bihty.
Rehablo atlning i. l nother 01 Ihe out·
ltaod,,,,, festu," 01 the KE·Jetronic .
The overrun lue! cUI'01l respOnds to
eng,ne Sf!"fId and tempet'ature and cull
off I'" supply ol luel du"ng decelerahOt\.
Ther. ere 1'10 unpleasent Jflfk. when lhe
luellJUpp!ycull back inagain. TIII.system
resulta ,n I redUCt'on 01 the luel consump'
tion and. ber"" ,. combu,!ion cea ....
dun"" IU'GI cUI'OlI. there 's no em,saron
OilOlrc , . ha,," ga. .....
Cle'ner • • h.u.' illS. .
The pre, 'C!u i.n.. lor m' n,m um pOllutants ,n
the Glhault g .. i, the prael,eally complele
combustion 01 tho luel. The KE')etfonic
,upplios o.ch c yli nder with precisely th~1
amounl of luel wh,ch ,s appropriate lot the
particul.r onq'no ope,a""" cond,l,on and
lot chlnges ,n Ioad'ng. For ,nstance, the
'eqUl(ed a,,·luel m"lure is pre<:!sely main·
t.Ilned II the l""eI nGCfIs"f)' lot m,n,mum
IOI 'C em,.. rona by reduQng the post·start
ennd'lment a. lOon . . possible. or by the
flpid r"pon" 01 the accelorltion en·
"ehment. Further ,mpr-o..eme<>ls ,n the
exhauSl g •• can I)., ..,1rieYed by employ,,,,,
the Lambda clo ....Hoop conlrol together
wilh o. hautl?, .llertrealmenl "si"" •
catalytrc convert ....
10
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Hig her pO we r o ulp ul pe, Uter
The elhc_tlr dearllned ,,,,nta ko Irslem
01 the KE·Jlltro..,c permits an ,ncreas. in
power due
improved cyhndor chargo.
The fuel·,nJecHon palhs ..e shofler, wilh
the ' •• ulllh.1 thero Ire no Ital spot. when
acceleration il needed. Simila, to allt h.
Olher Jetron,e . ytlom •. Iho KE'JOlron,c
Ich,e.o. I p,onounced oncreasod ,n
eng,n, pO_r lor tho sam .. piSlon displa·
cement. but noIlt the COlrt 01 ,ncrea.ed
lue! con,umpt'on. It allows economical
eng,rreslObedel'gned whichlesl"r, hogh
pow"''OUlpUI per lot ..... whole al the sama
hme d,.pl,Y''''' 900d 1I000ibility c:oupled
wuh e l ettllent dri....triluy.
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Sen'.,.
Po'''n'_'.,
Fuel di""'b",,,,
C.,."tOI "'''"9'''
C"",tOI ed~
1c Uppet cllambo,
7d LOW<It ch-.bo,
8 ".elyni«""n •• , ....
Q
,a
,,,,.kc_"i_
S .." •• Iw
"
Thermo·,i",. sw"ch
rhro.1io •• Iw
,3 ThlOW .... aI• •• wilch
r2
,. A",;/io" .. ,, _ _
15 E"g,,,.~ . mpe,.1ut."Mot
'6 Elecl"",i<: coni"" un" (E.CU)
,7 E'o<,,,,·hyd,".'ic
pre..",. <Ie'"alOt"
,8 Lambduen'Ot
19 /9"'''''''d,''~bo r ",
2{) Con'tOI ,.,,.,
"
U
BOSCH
/9"1"",,I"''''''9.Wtl.h
Bltlret}'
5
,
-- -
,
L
"
"
If
Basic functions
Fuel supply
TO}
Elect,i<; rue l po"",
I SUO""" ."'•• 11 P<e""Ie
~yslem conl!istsol an elocl'~ fuel
Rump, luel accumulator. luel f,lte,. and p..d:
.!!!.W'~~1!!!!2!
The KE·Jetfonic fuel system dillers only
sllghlly from that 0/ the lammar K·Jelronic.
An ele<;tricrolle,·C(!1I pump feeds fuel from
the lank to the pressure accumulator at a
p,essu,e of 5.4 ba" and from Ihere
through Ihe fuel filler lothefuel disuibulO'
(in &Ome cases. Ihe pressu,e is e.en high·
er, e.g. 5.5 ... 6.5 bar~. The primary'pres'
Sure regulalo, mainta ins the supply pres·
SLlre in Ihe system conslant. Md returns
Ihe surplus luel to the lan"- Due to the
conslant flow of fuel through the fuel·
supply system, cool fuel is always avail·
able. This pre.ents the formation of vapor
bubb les and enSures good hol'slarling
properties.
<~/ 1'''"'1'. •
,,,.ir,,. 3 Roll",..
MoW . ,,..,,,,,,. $ ND"-"',","
•• w". 6 A ....,,,, .",-.
"
.
'J) F"el occu",u'. '",
a: empty, b: ,,,~
I Spl,n9 ohamber. 2 S"""9. 3 SI""
• D"'phf09 .... 5 AccumU'OKl'
"""me,
F"~ ,.,.' OT ". " ... 7 Conn""".." '"
,6...
,,,,,,.,,t>e,,,,
•
::;:;;.:=.::=.::;;;; ;;::=.:===:::;
I rl O~er. ri"" "'TOIre,~.rI,,~mp
I S""r"'"
2 Raror pJ. ,• . 3 R<>il. ,.
' Raile< ,. cop/.ro,s PI ...u,. , .<Ie.
,.<Ie.
, ,.
Electric fuel pump
The eleel ris: fuel RlI!!!P dr a we I be lu@l!Wtof
the tank and deliyers il to Ihe II!!!I dr . uibu·
""
TIliI fuel pump ilself is an electrrcally driv'
en roll.,r,<;ell pump. It is self-priming. and
is filled inacommon housing logetherwith
the permanent·magnet eleclric molor (Fig.
17) Fuel ~n . ,
101. The malar is cooled by the luel which
I 1"1'01 /,Ire,
permanenlly suft""nds it and the pump.
The luel pump always delivers more luel
2
S".,"OI,
Ihan Ihe engone needs. so 1P'>a1 Ihere is
always sufficienl pressure in Ihe fuel syspia' • .
lem under all conditions.
The roller'cell pump itself consisls 01 a
hollow cylindrical chamber in which the
eccentric rOlor plate rolale .. The rollers ,_ _ _ _ _ __ _ _ _ _ _
ride in grooves localed ar""nd Ihe rotor's
perip~ry. and the cenlrrlugallorce resull- Fuel accumul,tor
ir;g from rotation lorces Ihem outwards so The luel accumulalor maintains the p.rH;
Iha! Ihey lunction as seal$. The pumping au" in !he fuel syslem lor a cerlain lime
action lakes place whan Ihe rollers. afte, aile! the en{liM bas bAAn I w ilchedoff
having closed the inlel bore. force Ihe Aher switch-(lff, the luel accumulator
Irapped fuel around in Irani of Ihem unlil it maintains the P'O$sure in the I"el system
canescapelrom thepumpthrOlJghlheout· in order to lacolaale reSlarttng. particularly
lei bore(Fig. II). A non·relurn .alve inlhe when Iha engine is hal. The design of the
pump{Fig. 10) pre.ents luef from flowing accumulator housing i. such thaI il dead·
back to the tank. as wefl as deoouphng Ihe enS Ihe sound 01 the fuel pump when the
ILlef system I,pm the tank.
engrne is runn'ng. The inlerior 01 the fuel
accumuialor ,8 d ivided inlO two chambers
by means 01 a diaphragm. One chamber
Fuel
Serves as Ihe accumulator for the luel.
iIi
!
while the olher represenlS the compensa·
tion volume and is connected 10 thealmos·
phere. by meanS 01 a vent litting. eilher
direclly Or th rough IhefueHank vent,lation
sySlem. Du,ingoperatron.lhe accumulalor
chamber is filled wilh fuel and the diaph'sgm iscaused tobend back againSllhe
i il
lorce 01 the .pring unlil il is hailed by Ihe
SlopS in the spring Chamber. The dra·
The filler is installed in tha luef line phragm remains ,n this pos,tion. which
downstream of the luel aecumula!", corresponds to the ma.imum accumulator
(Fig. 9). When the fi lter IS changed, it is volume. as long as Ihe engine is running.
;mp.erati.e Ihal the throughllow dire<;tion The fuel pump starts 10 pump as soon a$
as indicated by thit arrow on the housing the rgnllion/start swilCh iSlurned. and con ·
I,"ues 10 run when the e"gine starts. A
is complied with.
01._",.
,,
•
... " I
•••••
35.""""
'--_--.J
,
salely circua prevents pumping when the
Ignrtron is on and Ihe engine stalionary.fo,
e.ample alter an accident. The pump is
mounled in the immediale vicinily 01 Ihe
fuel lank and is maintenance·lree.
P / imarY'pressure . eg ul ato.
IhU!ti!!!a.ry,~gulat(}(
mainlains
.!!1i..ll!PIU1-I>rQssyrt CQnstant.
In contrasl to Ihe K·Jelronic. in which a
warm·up regu lalor regulales the conlrol
pressure, Ihe hydraul ic counle,pressure
actrng upon Iha conlrol plunger in theKE·
J"'ronic (see Page 11). is identical to the
primary pressu,e. The control pressure
mUll be held conSlant. even when fuel
delivery hom Ihe 5upply pump. and injecl·
ed fuel quantily, varyconsiderabl~. Thi, is
due 10 the laCllhat any varial'on of the conIrol pressure has a direct eflecl upon the
arr·fuel ratio.
Fig. 14 shows a sectionlhroughlhlt p,es ·
sure regulator. The fuel enlers on lhe left.
and on Ihe right is the relurn fuel connec·
lion from the luel diSlribulor. The return
line to the tank is connected at Ihe lOp.
Wh en the fuel pump slarls. il generates
p,essure and Ihis lorees Ihe control dia·
phragm 01 t~ pressure accumulalor
."".
f1J"'~_
t;
C.Iou<I
, -'-""1/
2 F,I/o<
• v.,.....,
! "'... -
•
"
1$) _ _
c_._.~
•
.,10._
.,.'W>..-II',
F"" 01 011. '" "...."'" dtopo 1_
"""'''1)'''''''''''
/0 ""Ioe .""'"9 ",",,",,
•• 1M "......,' '-11«10 ",I (2). /( ,,,.,. d".. '"
'5"'''' du, '" rho _
, <IIlho /utl """" _
' 01, Ie ,. • • " . . ( ! / wh",h .. I/;n _ ". ,,,.,
pr."ufe (4 / .
.
'"10<"0"-" '" _"'9
•
j
•
-------
•
dowt'lward. T~ prusure ot lhe coun·
'G.sp"ng IOreet Ih, oal., body to follow
Ihe dIaphragm unlil. after a very sho.' distance. il comes up .gains! ~ alop and I ~
pressure-controllunction s lat's. Theluef
relurn,"V from ,he fuel distribulor. compriling IIIe luel llow'''II1h'OUllh the prua .. ro a<;luato, pi ... Ihe contrOl-plunger
leakage , ell .. now flow back through lhe
open v.1~(I teat 10 the u.nk togelhe< ..,th
the e.ceu fuel. When lhe engine ••
SWItChed ott, ' .... lueI pump .Iso.'ops and
the S).' &m prell .... dropa.Asaresul\.lhe
...1.... pill' _ _ back up agaIn and .ub8equenlly pushes the .al.... body upward
&gaon" Ill. lore. oftl\e c;ounlerspring unl,1
the teal clo... the ,,,'urn to the tan k. The
p.enuflln the .y.tem then .inh rapidly
to betow the injectiOl1'vat"" opening pres·
su.e WIth the ... ult thet the valves then
clo..,. The , ystem pressu.a then in·
C••I I. . 1IIIIn to Ihe value dete.mined by
the luel accumu laIO'.
'li $pr., p.".mo II'om
• /(['JO'"","" f1J.r-ln;'.,im ...... wi'h
'/"' M>u6i~, (Ia_J . r06 wi'hOlt' (.bo..,).
7110 IN, h.....or,...,..M .~, oM ",omit. .
Ih. ' • • 1.....
(la_I.
b.,,,,
The inJeCtIOn ",I""s 'flJeCt ,he 1...1allocat·
ed by the Iutl d,.t.ibutor into the intake
portt di_'~ in l'OI1t of the cylinder intaka
vI I""s. The InjeCtIon valves are secu.ed In
a .pee"'l holder In order to insulate them
f.om the engIne he.t. This insulatIon p.e·
venlf vapor bubbl.. lo,mlng in the lue!·
injectIon lines whIch would lead to poor
51arlinll behaviour when the engine i. hoI.
The iniectlon valv.. have nO melering
function. They open 01 the" own ac<:o<d
when the opening pressu.e of. 10' in·
stance, :l.!S beri.exceeded. Thayare li tted
wIth • • , 've t>eedle whIch vib.ates ("chat·
t... s") audIbly" hillh Irequency when fuel
InjeCted. Th" results In e<cellen\
It>eI atomIzation. oven WIth the 5II1allest of
,nj4ICl&!! quantltl'" When the engIne Ie
" be,,,,,
Iw,tched on. Ihe injection valves ciou
IIghlly as loon .. the fuel'sys tem pres su,.
drOPI below thell opening pressu.a. Tlti,
moans thaI no more luel CIIn enter Ihe
Inlake PO'" once the engiflil has boon
SWItched ofl.
Air-sh ro uded luel·lnjectlon valves
",,·sh.ouded injection valves imp.O"ffl the
ml ..tu,. pt~,.tiOl1 panlCUl.,~ at idle
(Fig. 16). The ai,·,IIfoudlng p.inciple,.
baud upon tlte lact thaI a pon"", ol lhe ai.
d,awn in by the engIne enters tllfough the
I.....·injection val_ (Fog. 18) WIth tlte
'Hull that the lue! II HPe¢I,111 well atom·
ized It the POInt of e.'1. Ai, sh.ouding il
pan,eul.,ly ,nee!Iv, when combined with
the thin. contInuously """rali "9 K· Jel.onic
val""" and ,ea~II' in .. ,educ lion ollue!
consumptIon and .. lowe. leval of to.ic
emiSSIon , .
Fue l metering
reason, Ihe air-flow len_ i, so designed
that the senlO' pl.tecan awing back in the
8 ..ic11l1, luel metering ta~" pllce opposite direct.on in caS(! of misfire, and
through the air-flow sen_ and the fuel pa st its ••• o pos; tion to open a relief c.oss·
distributor, In a number 01 operating section in Ih, funnel. In tho case ollhe
model how_, the amount 01 luel down-Orslt .;.·flow senso •• an e<lension
.equi.ed d\IYiates g,..tly from lhe "st.n· spring compenNtel 1001he _ight of the
dlld" qUllltity. and it become, .....ellary IIInIOr 1'111. and lhe lever mechanism. An
adjusUlble INf Ipri~ i, filled 10 a"", ..
10 ,nl_ne in the fuel·management
tem. Such """nu..... a.e deah WIth .n the the correct .ero position in the switched'
ChlrptC1 on ""'i<lu.e ad,pl.at.on".
off phase.
'y"
Fuel d l'lrlbutot
,
air quafllity _ . II the ..... in
Klua"ng Ylriable for deletmining lhe ba·
tic i"fICtion q......,tity. " ., \he ,pp<opnate
phyaical qUlntity 10/ deriving the luel
requ. remenl, Ind ctranget in lhe indur;tion
chlr.acto.iltic, 01 the engi ... h•• e no
effect upon Ihe formation of the . i.·fuel
mixture, Since the air drawn in by the
eng in. muti pass Ih'''''g h the ai.·flow 8en·
_ befo'l il reaches Ihe engine, th ••
...... n. th.ll il h.I, been measured and the
conl.oI,.gl\lll generaled before il aClual.,.
lmar.lhe engine cylinder • . The ~Iull i.
1h.l1 .n tddition to othC1 meUures <ie,'
c .ibed below, the correcl ".;.1"'1 adapl.a·
I.on take, pl_ at all limn. The ai.·flow
. enso. i. ioealed upstream of lhe Ih.ottle
.llve lO Ihal it measurn all the air which
ente •• Iheengine cytinder • . II comprises
an Ii. funnel in which Ihe len'or flap
(. uspended body) i8 free to pivot. Tho .ir
flowing through the funnel deflects lhe
. en..,.. plale by a given amount oul of .IS
.. ro poaitron. and this mo.emenl II tranl'
milled by. 1\lYe< s)'$lem 10 a conltol plun·
gC1 which det .... mine. lhe ba.i<: injactlOf\
quanlil)' .equired fOllhe basic func:t.on ..
Cotr, iderable "",S8u~ ,hocks can OCCUr
in the .ntake 1)<Slem if backlirrng takes
place in the intake manifOld. For this
close, the slits 10 a gruler or lesse.
d&g'H, The fuel Itows through the open
section of th""e slill to Ihe diffe.ential·
p.ellu,e valves snd Ihen 10 tho fuel·injec·
t.on valves.
If lensor'pl"tetravel •• only very ,m.II, lhe
cont.oI plunger is only lilted . ,ightly and.
" ' result. only a alflllil .a<:tion of the ,lit,
i, opened fOlthe porssag.e of
On the
other h1rn.d, with. 1"{Ie< plunge' I••vel, t"plunger opens a larget sect..... of the Ilill
.nd mote 1",,1 can flow. The.. il' linear
"llIionlhip between sen_·plate t,.vel
Ind lhe llit laction in tIM barrel which is
oponod for fuel flow.
A hyd,aulio fo.ce is applied 10 thl cont.ol
plunger, Illd acts in opposition 10 lhe
movement ... sulting Irom tl're sen"""plate
deflection. A constant lir·fuel preuu.e
drop at the sensor pille il tl're r•• utl, ,nd
th.. SRiurel lhat tho control plunger
alwaya followa the movement of the sen·
_·pI.te I....... In some version ... a pree'
lur•• pring is used to ."ill this hyd.,utic
,,,,,I.
•
"._, ..... "'"".
-
,• -~--_ _ . ru,," Mtoo...,
5
Mo ,~_'
• t ...,
•
1 L ... f _" ~
2Q.1_ .... _ _
,...,dIo-...,
a_Ir'r_~
Iha
If
force (F'g. 21 ).U prevents Ihecontrol plun·
ger Irom beIng drawn up due to vacuum
elfecls when the sySlem cools down.
II IS imperative Ih al Ihe primary pressure ,8
accurately controlled. otherwise varia·
lions would have a direct effect upon the
air·fuel ratio (i.·value). A damping thronle
(Fig. 2 1) serves to dampen ","cillations
that could be caused by sensor·plate
forces. When Ihe MgiM is switched ofl.
the control plunger sin ks until it comes to
resl againsl an axial seal ring (Fig. 24). This
,s secured by an adju8tabl,ucrew and ClIn
be set to the COllect helght to enSure that
the metering slils are closed correctly by
the plunger when it is in its zero poSilion.
Whereas with theK·Jellonic.lhezero posi.
tionol Iheplunger i8 determined byitabut·
ti ng agai nSI t he sensor· plale lever. with Ihe
KE·Jetronic the plunger rests upon Ihe
.... ial seal ring due 10 Ihe force applied to il
by Ihe residual primary pressure. This
measure serves 10 prevent pressure loss
due 10 leakage past the control plunger.
~')
F•• I d;$lri&""" w;rh "m',.Au.,·
p~ ...
re •• ,.. ...
and thus prevenlS the fuel accumu lator
from emptying through the conllol·
plunger gap. The luel accumulator must
remain full. because it has the job of
ma,nta,ning the primary pressure above
that fuel·vapor pressure which is appli·
cable lor Ihe panicu l.r fuel temperature
preva,ling when theengineis switched off.
22) D;ffo,. Ali.,·
•• m .
p~... ~
(p,,,,,,,,,
, F.eI''''eI
P"''''''.). 2 Uppo'
c.ombo' 0' d.lI.ron".,·p""." •• "'0. 3L.n.
Ioel·'"i«' "'" ' ."" • • C."'roi ",."geT.
S COni"" edg. ond '''''''''"9 .M. 6 V..,...
'P''"9. 1 v. ".. tJ;~ .. g"'. 11 Low., c"""'~'
•1
9 A ... , _
ute "".09. " F""II",,,, ,...
oI«lro·hyd' ."'''' "",.. "~
,2 ThroW'"9
Re'"," ,;"..
0;
0pt0"M9 po ...
."" ...,••m""
'0'••
'"1*""'"
Q"anlllr
&: 0""..,,"11
""_"".p, ..."," ••".•.
""9. '0 ""' ..
oo'u.'.,.
poor'ion .-;,/0
'"'ge '"I""''''''
quon"'r·
"'''''0''''''. 13
,CA."'.
01 ." dr."", In, .,n"" pl. 'e
""".,.~od '~9"'r. I>: Lo' ge ''''''''0' 0/." d,. .."
m...rlng .un .M <"",toI plun"".
u) P"<>CIpie Df ,h • • it·R_
24) S..,.I with
o. S",. II .""",",
. , Z.", (;"_~ted po.,'.on). b:
,no
M"_ p"',e,. /JrerJ con.Id".0I1
-.------71
I",,~,.
upper and lower chambers constant. ,nde·
pend""t of fuel Ihroughflow. The differ·
ence ,A pressureis u$uallyO.2 bar,and th,s
ensureS 8 h'gh degree of metering accu ·
racy. The differential·pressure .alve. are
of the lIat·seat type. and a,e located in the
fuel dist"butor. The upper and lower
chambers are separ.ted by meanS of a
diaphragm (F'g. 21). The fowerchambers
of all the .alves arB provided with a helical
spring and a,e connected to one anothe,
by means 0 1 a ling main. as well as 10 the
electro·hydraulic pressute aCluator. The
valve seat is located in the upper chamber.
and each uppe' chamber is connected toa
metering slit and its cOffesponding fuel·
injection line. The upper chambers are
complelely sealed ofl from each (llher. The
pressured itlerential al t he meter; ng slits is
determ,ned by the force of Ihe helical
spring in Ihe lowerct>amber. togelherwilh
Ihe effect,.e diaphragm diameter and the
eleclro·hydraulic pressure actualor.
II a large basic injeCI,on quanmy flows ir.to
Ihe upper chamber. thed,aphragm bends
downwa,ds and opens the outlet croSS·
section of the val.euntil thesel diffetenlial
p,essure i8 , ..ached again. If the through·
flow quantity drops. the valve cross·
section is reduced due to Ihe equilibrium
01 fotces at the diaphragm until a ptessure
dilfl!fcntial 01 0.2 bar prevails agai~ .
This means that an equilibrium of forces
e,ist. at the diaphragm wh,ch ClIO be
maintsined fo, e.ery b.. ic Injection
quanl'ty by controll ,ng the valve Ctoss·
section. An additional line liller with a
separator for feffomagnetic contamina·
tion is litted in Ihe luoll ine to the electro·
hydraulic pressure aClualor.
p."
Iood. c: lull
01";" r... N ,re/. 4 C OII'roI edg •. 5 s,,,,e/. /;
1<>.0". I F",,' inl. '. 2 Con'roJ pI"n~o'. 3 M.'.""9
Ax,., _
7
r~",m,"g
... ,''''''''".
•
,
If
Mixture adaptation
Basic mi xture adaptation
1t! I~JluItllC . 01 _ _ ~ """"
......... __ ,..... IhIlKNott "" 01'-..,
Electronic control unit
"'_,/op"L
a: r". b,..", 1Io~"" 0li<l,. ......11. '" .,...... 'b",
b:
~ 110""., ...""" _
'" _ _.....
s..
"flll. "h' /0, "'""''''~ .;, ,h""'ph"..,.
c: Fl."", /u"".,.,,- ",un, ;" ted.c'"
For ea~h oporM,ng mode IllS necessary to
carry 001 milt",. adaptation in o,der 10
provide the '''iI,n, Wllh Ihe opti mat ai t· j uel
"".<lUI'. In p!'aclice, thi. muna that.
de"K'_ 'h'/o, id.",,,,~ •., 'hrnughpu"
by'''' 'en""
pia ..
,n •••• "b",.1td "C"J.
CI A""",,, .... _ _
(ode",<c~
,,,,he. m..I\". " '~UI'ed .1 'die and lull·
load, and .Ioa...... "". !Ure lor the ~-Ioad
range........,ed abo-te. the basic adap ... ·
lIon II by 'pp!'opnalfl all_pong 011'"
lul'ltMtl. For in'lanc:e, ilthe funnel ,. flatter
••
•
.i.,
(Fog. 26c) I"'n the basic form (which was
lpec:,li&d 01'11' nally tor • 1I'.... n mi. lure, e. g.
at,, · 1),lhen them,,'ur.islear'le<. lf,on the
olher hand, 1he funnel walls are Sleepet
(Fig. lib, b) lhan in \he ba~"c form.lhe mi. 1ur,,' ,;che, beea" Ie the sen"" , plale de"
lectsfu, th,. 10' the ..me .ir throughflOw
and the con Irot pi ungm mol ..", more luel.1t
I. p....'ble 10 ,h.pe Ihe ai. funnel so Ihat
an
mi.luro cOflesponding 10 the
"n"'f-pl.t, po"lion (klle, pan load, and
luliload) can be me1eroo 10 lhe engil\8, In
'''''CIHOI IheKE"Je1ronic. I"".rt lunnel i.
prelerably 1IO.nape<! lhal a n air.fuel mi , "
IUle w,lh 1. .. 1 <Quit, actoas the whole
operallng ran"e.
.,,·1"0'
I·
•
Senso" lor Ihe re"tst ral lo n 01
opelaltn" dltl
Add,' ional O/ite"...boYe a nd beyond tlMo
<IItorMal1On como"" I.om lhe intake ai.
quantity. a'l teq ";,ed in orclet to ""t.... m' ne
lhe oplim-, 1..eI q..- nlity require<l by the
"""il\8. TII_ mull be "'9;S'ete<l by ""'"
_I and rlported 10lhe ECU"TlMo sensorl
a •• dll$Cl'becj wolh .eI... ence to lhe cot ...
spondn,,, adaptatoon iuncloon.
==----,
A(J.p,.~""
o' th._.1
'''"'.nh.'
0lI.,..
FtN,.,,_.
, FtN ..,,,"'"'"
!F",_
\ !-:
\
\
I
. ..
\
0 " '11" end lunellon
Input flll ..s
TIIHe filt", OUI...,. interference which m.y
electronIC eorcu,lry u'" e;ther analog be pr.....1 in the .ncom.ng signals frOtl'l
technique. or mlted .nalogldigif.allechni· lhe ""sora.
c,ues. St.rt'"\1 wIth the "Europe" unil. lhe
module. lor ,dl,-m..."., conlrol and lOt Add . r
lambda cloled·loc.p control ca n be add · Her •. the e.slu8tOO s e nSOr s;gnal s are
ed. EeU', wilh. mOre ' .Ienaiye rang e of combine-d. Th, .Iect.icalty processed COr'
I.. nclio"s .r. desig ned uSing digital tec h- recti.e .ign.II"•• dded in an operat ional
niquel . The ellICtronic components are ciroui l and Ih.n trans mined to the current
installed on. PC·board and include IC', ragul"C>r.
(e.g. op6fltion.1 .mplifi~ •• compa,alOrs,
and voI\.lge . 1.bOlizer.), l.ans;ll0' •. Oulp ulsllg.
diodel. ,eli"orl. and .... pacilors. The pc. The out""t st~ g.neral.. the conlrol
oo..dl
,nserted in .he Ee U housing signal lor the pressu" aCluatC>r. whereby
... hie" can be eqlOlpped with. p'esstIf~ il i. possibl. 10 in""t opposing currenlS
equal,nllion ... ment. The ECU Isconne<:l- into lhe prellu" aclualOr in order to
ed to Ih, ban.".. !Ollie Ie........ and \0 the .tICI. . . . C>r d_eue the pressure drop.
actu.olor by. 2~·poI. pI...g.
The magnilud. 01 the current in the pres"
The EeU processes the incoming signals IUr, Ktu.tC>r elIn be .djusled al win in the
from lhe d, tt,'ane ..... IJOt •• and from 'hem pos.t"" d" e<:t.on by me .... 01 • perma"
ulcul"e1lhe COIII.ol c .. " .... l loI the e lee- nenlly triggert'd IranaistC>r. The current i.
reverH<l during ' OYer",n' (oyerrun lue!
'ro-hydraulic prell"" IClu,' OI.
cut-oU). •nd influeflCes the differe ntial
VO' Utg e . ,. bUlntlon
pre"",, al the d iff.rential·pren ur,
The eeu muSI be powered by aslable . oll· .al"el so that lhe flow of luelto the ;njecage. which rem.ins conslanl ind epen' tion ",t".1 i. in lerrupted.
dent of the vo ll .ge of the • • hicl. eleetrielll
sySlem. The CurrO", applied to the pres· Addltl o nll output s tlges
IWre actualOr. which depends upon lhe II nec....ry •• ddit",",,1 output s lages elIn
incoming sensor "g","ls elI.rying lhe dala be incorpe>rlted. Tile.. elIn se",e to trig·
on the engine ope<"ing conditions. i. II"r lhe ••1.... lor EGR. and to control the
g.nOt.ted ' rOtl'l thi. stabilized voltag •• the bypass coos.-Mellon .round the throttl.
alabili" lion of whic:h tak.. place in a spe- nl ... " .~uited lor idla·m .. ture control.
co.IIC.
10 name but two .ppfiClltlont..
Dependinv upoII lhe ' unctlOnal scope. \he
.t,
ttl _.,...,_ 011"" /IE· h _ lieu.
...... ...., t«JWouo ..
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Electro-hydraulic
pressure actuator
ue is proponionalto this control currenl.
j he
basic moment 01 lorce applied to the
Design
The eleclro-hydraulic pressure aclualO<
(Fig. 30) ism ou nted on I he fuel d ISlribu lor.
rhe acluator i s a din erentil l-pr ,,5sure con·
Iroller which tun(:lions according 10 the
nOZ2lelbaffl" plate principle. and
prossure d rop is controlled by Ihe cu rrenl 'nput
Irom t he feU. In a housing of nonmag ne1 ic
male rial. an a rmature is suspended on I riclionless taul-band suspension elements.
be1ween IWO double magnetic poles. The
armature is in Ihe form of a diaphragm
plale made Irom rnilient malerial.
,t.
Fu n(tlon
The mag",,' ic III" of a permanMI magnel
(broken lines Fig. 30). and lhal of an electroma~nel (unbroken lines Fij' 30). are
superimposed upon each 01 Or in Ihe
magnelic poles and their air gaps. The per·
manenl magnel is actuslly lurned through
goo referred 10 the focal plane.
The palhs la ken by Ihe magnelic flu.es
through Ihe lwo pair. 0 1 poles are symmet rical a nd 01 eq uall engl h. a nd II ow from Ihe
poles. across Ihe air gaps 10 Ihe armature,
and then through Ihe armalur •.
In the Iwo diagonally opposed air gaps
(Fig. 30, L2.L3). the permanenl-magnet
1Iu.. and the electro·magneillu. resufling
Irom Ihe incomin~ EeU control signal. are
added. whereas <n Ihe olher two air gaps
(Fig. 30. L I.L4) the lIu,es are subtracted
Irom each other. This means thai in each
air gap the armalur.e. which moves too
b-ame plale, is subJecled to a lorce of
atlraction proportional 10 Ihe squareof the
magne1ic flu •.
Being as the permanent-magnet flu.
remaons constan!. and is proporlional to
the con Irol current 1rOm I he feU flowing in
Ihe electromagnet coil. the resu lting t",-
armalure has been selected so lhal when
no currenl is applied from Ihe EeU. there
results a basic differential pressure which
corresponds prelerablytoA - I. Thisalso
means that in case 01 control current fai·
lure, limp-home Jacililies are available
wilhout any further correction measures
bein~ necessary.
'"'lei of fuel which enters through the
non e altempts 10 bend Ihe baffle plale
away against Ihe prevatlinij mechanical
and magnetic l",ce8. Taking a luel
throughflow which is delermined by a
Ii, ed restriction located in series with the
pressure actuator. the diffe'ence in pressure between Ihe inlel a nd ouHe1 (Fig. 2 8, 3
& 5) is proportional 10 the control currenl
applied from Ihe EeU. This means thai the
va,i able pressure drop all he nozzle i s also
proportional to Ihis EeU conlrol currenl.
and resuUs in a variable lower-chamber
prnsure. At the .ame time. the pressure;n
the upper chambers changes by Ihe same
arooun!. Th,s in lurn resulls in a change 'n
lhe difference at lhe melering slits be·
Iween the upper-chamber preasure and
Ihe primary pressure. and Ihis is appl ied
as a means for varying Ihe fuel quanlity
delivered to the injection valves .
As a result 01 the small electromag""'ic
lime conSIMts. and Ihc small maSSeS
which must be moved. the pressure aclua·
tor reacls e., re mel y qu ic kl Y10 variali ons in
Ihe control curre nl lrom Ihe EeU.
If the direction of Ihe control current is
reversed. the armatur., pulls Ihe baIlie
plate away from the n02zle and a p,essure
drop of only a few hundredlhs of • bar
OCCurS at the pressuro aCluator. This can
be used for au, iliary lunctions such as
oWlrrun luel cut -off an d engi no 'speed Iimit.alion. The laller function t.akes place I)y
inlerr upti ng I he flow of I uel to Ihe ,n jecli on
valves (see Page 21 ).
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10 O!IS!'''IO'''I!\j~ "AI$!:>ap 94' ·luOlo'II"":)
",n!B,;)dw;).1 "A!leBoN ;OJ SPUll'S :)IN
Full load
Idle
i
!
Full-lo ad e nrichment b~ means ol lhe
pressu.e aelualo.
I ~ oo ~trast to p art load_ where the cali bra.ion is fo r minimum luel consump"on and
IOW e missions, a II uilioad it is neee s sary to
enrich Ihe air-Iuel mi. lu.e. Thi. enrichme nt is programmed to be engine spe<Kl dependenL I. provides ma. imum
possi ble .o. que over Ihe e ntire e ngine s peed range_ and Ihis enSureS oplimum
luel-economyf igures in thefull-Ioad mode_
Ai fuilioild_e_g_in Ih .. .. ngine s pe<Kl rang .. s
be twee n 1500 and 3000 min- ' , and above
4000 min- '_ the KE-JeI.onic enriches Ihe
a ir-Iu&1millu.e_The lull-load s ignal is deli vered by. full-load s wilCh on Ih& throttle
valve_ or by a microswilch on Ihe acceleralOr-pedal linklg e. Th e informal io~ on
engin& spe<!d is .aken Irom the ignilion.
Fro m this data. the ECU calcula.es the
addi liona l luel quanti.y ne<Kled. and Ihis is
put in.o e ffec. by the pressure aeluator.
Controlling the Idle speed by meanS
ollhe auxiliary illr device
The higher Irictional resistances in the
cold engine must be OVe.come by increasing Ih& air-Iue l mixlu,e input. In o,der 10
achie ve Smoolhe, , unning al idle. the idlespe ed conlrol increases Ihe idle speed.
This als o leads to a mo,e 'epid wa,m,.,p of
Ille eng ine. Oepending upon engine tem perature. an electrically heated au.ilia'yai, de.ice in Ihe lorm of a bypass a rour\CI
Ihe Ih,o\1le plale a llows Ihe engine 10 d ,aw
in more ai,. This auxiliary air is also measured by Ihe air-flow s ensor. and leads.o
Iha KE')et,onic providing .he engine wilh
mOre fu .. 1. P,ecise adaptation is by means
ollheelectrical healinglacili.y. The engine
lempe,ature Ihen del&rm ines how much
auxiliary air is led in initially I",eugh Ihe
bypass. and lhe e lecl rical heal in 9 is mainly
responsible fo' subsequenll y reducing
th& auxil isry air as a funclion of lime.
The au. il iaty-air device inCOlporalesa perfOlalOO plale (Fig8. 38. 39, 42) which is
actuated by the bi metallic 8trip and which
conlrol8 Ihe cr08S seclion of Ihe bypass
passage. Initially, the bypass CrOSS sec·
tion opened by the perforated plate is
dete, minOO by the engine 'emperatu ,e, $0
lhat d~ring a c~d Sl8l1 the bypass opening is adequato 10' the auxiliary a i'
required . The opening closes Sl&adily
sloog wilh incr .... sing e ngine tempe,atu,e
unlil finally il i9 closed completel y. The
bimetal si rip iseleclrically healed and this
limits Ihe opening time, starling lrom the
initial setting which is dependenl upon
engine .emperatu'e. The auxilia,y ... ;r
de.ice is fitled in the be st possibte posi _
lion on the engine fer it 10 assume eng ine
temperatu r... It does "<ll function when Ihe
eogine is wa,m.
31/ Ci>nl rol arc,,111or lb. cI<J,. d-loop
""",not
Idlo-op"d
In eMI,. " '" Ihe OPM-""",
«II• .
e<>n1O>J. ,100 cl<JU>dloop COIIIm!
,h •
sp_
_ os."',
• ,""., ~n9'1HI ,pe«i. Thi.
69"'- .. ,ho" <om;n~ .",h
,h ~ .. , •• ,,," ond. in cu.
,/00
oIi<l<>;"
d,,,,.,.,,,. "'IO,mg g'
The throttl e-val ve switch (Fig . 36) is
mounled on the throltl e body and aclualed
by 'ha throUI&'valve s haft A Separale contact is cl osed ler each 01 the Ihroll le·va lV<!
end position s. i.e . • , id le and 1.1 lull load.
,h. idI<J·.".ed "'IO,>, "10".,.,
.,"em:
, dlu'ted ,e"",d,,,!}'y.
, CQM",rr.d
. ng.no.
2 fAr"", ,1<td .. ,iobl.:
ongi". . , , - In).
3 fAr"",II.~ ""n' fOI
,100
<I""
(d.Ii"",.
conl,o!
...". ~
4
~
~;".I
u.J.
C",,'fOIling
01""0."
idl. <pHd fOro". "
.,.,bIe;'"orot,
Mooipulo,ed
byp ...
c"'.. ·.ec'ion 1;'''. lo~II
quo",i,y 1'0)
6 A",ili. ,>, oc,,,, "ng •• ". bI.;
",mpe'" .''' I"';.
'"9''''
7 Au, di' ". OCI"" i"9 ""~:
,h",W• ..,. "", <rid p<><i6on 10
- OJ.
38) t loc<rl<. ",. h •• ,.d "" . IN~ "_",
(o«lion) . , PI". openl,,!}. 2 Air P....~.
J Perlouo' ed pt.,• • 4
6 tlec,,;u.1 hHMg.
Pive'.
,
3'
tlKtriul/r' h ... red eQ. illo"..;. <1<>-';';• •
, f lee";';.1 e<>n _'io~. 2 EIee'''''' ' Mo'i"9.
3 e;lmtlOl ."ip. 4 PeIlrNOIed pI~ '• .
3~J
5
I
•
J6) 1l'I",,,,&........, ,witch ""
&"d."Os;l.",o;I"-'_
If
Idle
5feed
5 tIlP///Z e l'
by means 01 the
Excess Ive idle speed ,nCreases the fuel
consumphon at idle and. as a result. Iha
vehicle's overall fuel consumption. Thi,
problem is addressed by the idle·mixture
conirol, which always provides e,actly Ihe
rig hi am Gunl 01 m, .tu '" in o.d 8f 10 main lain
I ~ ,die speed, no mallerwhallhe engine
load (e .g. cold engine with increne<! frielional resistance). Furthermore, Ihe emis·
sion ligures ,emain COllstant in Ih" long
term without having 1(1 adjust the idle
speed. To a certain e,tent. Ihe idle-mi.ture
control also compensates lor changes in
lhe eogine which ar" attribulablelosgeing.
11 also slabili~es the idle speed through-
out the entire service life of tile engine,
Depending upon Ihe signal applied to il.
the rotary idle actuator opens Or closu Ihe
4()) Role'Y jd/e ..:Ioel'" I';~!I/e-wj"dm~
tar.". eOl"el",).
r Ele<:w".1 CO"_" .... 2 H"" ••",. S Rewm
'p"",. ~ W;~·", . 5 Ror".ng_,,,,,,Me. I; ,l.j,
p.... g•• , blfn. . ."",od ",• •hfOII/e pl• •••
1 MI.".blo ,tw>. a Ro •• r."f) ,ltd• .
bypass passage around Ihe lhrOll1e val'e. specified idle speed 10 be mainlained
Oue to Ihelacl Ihal Ihe KE-Jelnmic regis· independenl 01 engine loadir>g. The clos·
lers tl>\l resulting enr. a;r w,th its sensor ed·loop conlrol circuil in Ihe ECU, which
plale. tl>\l injecled luel quaMily changes i~ provided by the engine'8peOO sensor
accordingly. In conlrast 10 other idle· wilh Ihe n~ssary inlo,mal ion concern'
speed conlroi Son Ihe market, Ihis idle' mi. · ing engine speed, compares this with Ihe
lure device controls Ihe idle sp""d effi· programmed specified idle speed and
ciently due to itactually carrying oul a com· adjusts tl>\l ai, Ih,oug hllow by meanS of Ihe
parison between desired and aclual idle acluBtOl until the actual idle speed
values and. in caseol dIWialion. correcting coincides wilh the set idle speed. Wilh the
eng,ne warm and unloaded, Ihe bypass
accordingly.
opening is very nea, to ils lower limit.
Further inpulS lrom the ECU, such as tern·
perature and throttle.yalV<l poSilion.
ensu,e Ihat errOrS do not <xcur at low lem·
pe,atu,es or due \0 accelerator·pedal
movements. The ECU transforms the en·
gine'8pood signal into 8 voltage signal
which it compares with a voltage corre·
sponding to these!valua. The ECU gene'
,ales a control ~,gna! lrom the diffe,ence
The rotary idle actualor 01 Ihe KE· Jetronic voltage, and inputs this to Ihe rotary idle
(Figs. 40. 41) r~ives ilS conlrol signal actuator. A pulsaling OC is applied to Ihe
from Ihe ECU. This conlrol s ignal depends w,nding ol lhe co, l and causes a torqu e at
upon engine spOOd and tomperature, and the rOlaling arma!u", which aclS against
ca uses the rotating plato in tho idlo aclua· the ,alurn spring. The resulting bypass
open,ng depends on tl>\l Strenglh 01 the
tor 10 Change Ihe bypass opening.
The rotary idle acluator is powered by a curren!. In the abseMe of current (vehicle
rotary·magnet drive comprisir>g a wind,ng mallunclion). 11>\1 ,alum spring forces Ihe
and a magnetic circui!' lIS rolalional rang e rotating slide against an adjuslable stop
is limiled to 60°. The ,olallng shdo is and p,ovides an emergency opening. At
anached 10 Ihe a,malure shah and opens 11>\1 ma.imum on/off ,alio 01 the applied
Ihe bypass pusage lar enough 10' the pu lsalir>g OC, the bypass is lully opened.
4 I) RotlHy I~ /e .01•• 10<
(o;"s!e -wlodm9 tOl.'Y ..:IU",OI).
42) Auxl~"I .. jr . e/vlr (lop) !HId I.",,,.r.'. __
Un_ /or k!!e'S/Jud
."",taI.
If
Supplementary functions
Overrun (deceleration)
C~l1jng olf lhe fuel during decele ralion
,educes luel consumption no! merely on
long downhill run. and during braking, but
also in lown Ira/fie. Be<;ause no fuel ;$
burned. the,e are no emissions.
When 1he driver ta~ es h is fOOl off the a<:<:eleralor pedal while driving. the Ih,otHe
valv" relurns 10 Ihe 2ero position. The
throttle-valve switch ,eports Ihe "th roWo·
va lve closed" corldition 10 Ihe EeU, which
all he same time receives I rom t he j gn ilion
Ihe dala concerning the engine speed. II
the aclual engine speed is within the operating range 01 the overrun cul 'Of! (Iha! i.,
above idl e), Ihe feU reve rSeS Ihe curren l
in the e lectro-hydraulic pre,.u." actuator.
The pressure d rop 81 the actuator is Ihen
practically zero. This means Ihal in Iha
lu," diSlribUlor. the d ifferential'pressure
.. alves are closed by Iha springs in Ihair
lower chambers (Fig_44) and interrupllhe
flow 01 fuel 10 Ihe injection .. alves.
Being as Ihe injeclion .. alves inject conlin'
uously. Ihe overrun fuel cut·oU opera l es
perfectly smoothly. liS response is also
dependenl upon Ihe coolant temperatura
(Fig. 46). and in order 10 avoid con tinuous
switching in and oul al a gi ven engina
speed. adiUerent swi tching poinl is speci·
fied depending upon whether Ihe engine
speed is decreasing or inc reasing. The
switch ing thresholds are chosen to be as
low as possible fOf the wa rm engine in
order lhal ma.imum fuel savings are
achieved. On Ihe Olher hand. wilh a cold
engine Ihe th resl>olds are somew"'l high·
er $0 Ihat the engine does nol stop when
Ihe clutch pedal is suddenty pressed .
r.., ,. i'ia. ~ J)
Wl>en
,.ke. /".
,~ . do...,
/001 011 'N IO«.to,oro<
"....,. 1M, .,.,,,," /uti C~I-oIt , ••ponM oltd
SI.P> Ih. /Iowot/uo! to Iho ;ni«r;"" ,owe ..
rut I. Fig. 4 4)
Futl cu,-oII.IIe,;,;.e durinll ove>"",n, Who" ,,..
cu,,,,.' .. """"_ ,h""'lIh 111<1 wiltd'"11 (! I) ,"
,,,. .o--"u", .<tu''''''. ,h. I>ollto
(!~) i.
pullo<! . woy ,"'"' ,11<1 ••,,," (IO). TI>I. Uu,,,
III<IIow.,."h.",oer ,DIe"u'" to riM 0"""" "" ,""
"""01 tho {""'"'' P,••• u,.•• 1td ,"" 'PrI"g' in
'M, """otd._IS closo ,,.. infers (S "nd 5) ""
pi".
,"" "'joerlOll ,01> •• wo,h ,,.. diopirr"J'" (8/.
IF",,' disrriburo<. ~ Fuel into,• • "" I~ e <oId·,,"~
,aWe. 6 '0 ,11<1 pri~rrP"'''u''' "'go/ar",.
1 U~, .h __ r. ~ L-., ch.mber.
If
'"
.6)
Engi ne-speed
limiting
rho 10""" ~"g;n. 'p""d lot' ,h.
Q'."""cool8M
fuel <"'.oW fllCdily depond.
"pM!
'. mp . ,~'u",.
-'
'!'iM"_"-P~i!!.u;I1ee<l is r.... ched.
Ill. ECU suppresses Ih. iuel·inj!l£!iru!
""'"
i
ConV<!nt lonal mechanical eng,no'speed
limIters haveadiSlribulor '0101 arranged to
shon·c;reuil the ignition when the maxi·
mum permissible eng,ne speed is
reaclled. Today. for ,eaSonS 01 ... hauslgas emISSIons and fuel e<Xlnomy. Ihls
!
'='~"i;~..,~~;;~~
211-10010 r.o
eooa-_".,.....
30
\\ooc
70 !IO
.7} U",;/inIJ ,ho m.,imum "nllin" 'Peed ...
01 >loppinll 'he ".W of f" . 1,. 'he ;"ieer"",
-'
•• 11' •••
.
I
!
"
;teo .....,
~
.....
",00_
,w"'<ho<Ioft
fool,";"",,"
ow,"''''''',"
.m
=
~~,
0
T.... ' -
-
....
""'''\1
0110< ...
,m
0
Adaptation of the air-fu el
mixture at high altitudes
method is no longer entirely salisfaclory.
An ob .. ous m<lthod i510 apply electronics
to engine-speed limi,ing by switching off
the luel injeeri"n. When Ihe current
through Ihe eleclro-hydrauhc aCluator is
reversed. Ihe bame plale is pulled away
from lhe nozzle (Fig. 44). Ihe pressur"
d rop approaches zerO and lhe dia'
phragms inlhedifferenlialpressu re valves
SlOP Ihe flow 01 luel 10 lhe injeClion valves.
The same process lakes place as wilh
Ihe overrun luel cul-aU faCIlity {rel" r 10
Page:20).
In the ECU. the aClual engine speed is
compared wllh the programmed ma .. mum
speed II•. If Ihe maximum speed is e xceeded. the ECU suppresses Ihe inje<:lion
pulses. This lunClion operates within a
bandwidth of 80 min ~' above afld below
tho permissibl e ma ximum speed {FIg. 4 7).
This e locl,onic er>gine·speed limiting
facility prevents the engine Irom -Overr<)V"';ng-. bUI without Ihe adverse eUects
inherent in the mechanical s ySlem mentioned above,
AI high ali'ludes. due 10 the lower air den ·
sily. Ihe volumetric flow measured by Ihe
air·llow sensor corresponds toa 10we<!l1r:
~. Depending upon Ihe I3cil:ties
inco'p",ated in Ihe particular KE·Jetronic.
this error Can be compensated for by correeling the inject'on time. Ovcr-enrichment is aV(>1ded and. therefo,e, excess ive luel consumption at hIgh aliiludes.
The alt'lude compensation is prOVIded by
a~ wh,Ch meaSureS theair PreSSure.
In accordance with the prevaIling ." pressure. the senSor ,npulS a signal to Ihe ECU
which changes the press"re-actunior Cjt!;
rent accOfdongly. (hIS allcrs Ihe lowerChamber pressure. and therelo,ethepfes·
sure d i!ferance at 1he metMing SlilS. and
Ihis ,,!'Sulls in a change In the inj(lCted fu&l
quanuly.
It is also possible 10 incorpora le continuo
ous adaptation oflhe injected ruel quanlity
according to the char>ging.If prIl'SSu,e,
T~.,
toFjg. 4 S
At c<,,,,.~,aOl. n..gh .. 4_..... 1
•..-1. ,h.,. '.
• .igm~.'"
boI_
"",a,u"'"
dilf.",,,,,.
,h.
." "".n"'1 ~ nd ,,. ",'u-' 1M... n", IS duo , •• "
Mn" 'r d"",. ...nu _, ~'f1/> -,,,,ude •. A""",·
me'"" _'",rxI• ..,n,,,, ,"0"=' rho." p,...
.nd ropon, ,h,. ro ' .. £CV wh-ch .dJ""~ 'ho
mJflO"'" fue' Q""""'1 KCOIdinll'r by """n' 0'
'ho oI<re,,,,hy<J, .,,"" jUo".'"
=
""",,01.
Clean emissions
2
Fuel combustion in the engine working
cylindo< is more Or leSS incomplete, The
less complete Ihecombustion, the higher
=-------3
is Ihe emission ollo.ic substances in the
exhaust gas. Perfect Of 101al, combustion
of the fuel is impossible even when Sur·
plus air is avai lable in plenty. In order to
,educe Ihe load on the environm""t. it is
imperative thai engine ... "'-uSI·gas emisThe t hr~.way catalyt ic converter has f8) c.'MrIk; <Oq,"'.,.
sions ar" reduced drastically.
All measure" taken to reduce the to.ic come into widespread use. Theconvetle, WIt •• •• h o~ .. g. •• • lIow ,h"'ugh 'h" <''''pi<;
emiss ions in compliance with a variety "I shell contains a ceramic 'honeycomb" ""....".'••Ito pl.oMam ..:oele,.. ,• • rlto ch.",;co'
legal requirements, aim at achievir>g as which is coated with a noble melal, pre' <10<"",1'00'."" <>I ,Ito 10"< ,ul>$'ooe ..,
r COlO"'" m.'c'~ c",,'od ""'h
clean an .. ,lIauslgas as possible, while al ferably platinum. When lhe exhaust gas 00
••• mo,.,,;a, (pIa".um). 2 S,HI _Io,
Ihe same lime featunng optimum fuel·eco- ffows th,ough thi s honeycomb. the plati· 'rx:."~g pu'PO"''' 3 Co"M'" . h-".
nomy figures. ".cel len! driveabilily. high num acceleratea the cf>emical conversion
mileage ligures, and low inSlal lation COS1S. of Ihe toxic substa r.ces. Only lead·I,ee
In addition 10 a large p",centageol harm· gasolir>e may be used with such COnver·
less substan~s. tf>e e.haus t gas 01 a ters because the lead othe,wise destroys
spark·ignilion engine conlains cotn~· the catalytic property cl the noble-metal
nenlS which are harmlul to tf>e environ· calalyst. At p,esent. lead ·I,~ gasoline is
49) ~Ifce'in .... <>I,he colo!ytk; do""","
"",.1 of ,..".",1 g .. ".j.~ III" Umbd.
ment when they QCcur in high concanlra· only available in Japan and in the USA. and
r;lo •• d./oOp _''''',
lions. About! ," of thee.haustguis harm· loa limited e. tent in the Federal Republic
Ro.g. 10, .po",amo,,.,,,.1",;,tu,.: I. • 0.99
lui. and ""nsistsol carbon mono. id .. (COJ. 01 Germany. For this reason. catalylic COn'
_ 1.00. To.",c""',,,"" o -lIt!.l!!s!tao 1r. ",. .,·
o.ides ot nitrogsn (NO.). and hydrocar· ve,te" can only be used in these coun·
"",n( b - !!:!!l! airOtf",. """n( He hfdto<o_
bons (He). The major problem in this Iries.
CO 00' _ """,",-d•• NO. ",.d.. 0' ",,"'ge • .
respect is the lact that although these The prerequisitelorcatalyticconversion i.
Tho Ifi.g,.mbelow d• ...,."'... . lito co.,;·
th ree to.ie substances arB dependent that the engine burns an optimum ,i,·luel
doIob! • • " • • , 10 ,,/loch .,h' ''''·g'' om,.,
,ion, co. bo -'aceO I>y , • • opplic""," 01
upon the air·luel ,al,O. when Iheconcentra· mi.ture. This optimum. or s toichiometric.
C''''y'''' . 1",,,,,,arm.,,, and by lito .,,·/Uol
lion 01 eo and He inc'eases the concen' mi.lure (s~ Page 4) isa[(iyed alwhen pre·
m
.. ,,,, •• Th •• _a'.
y 10,. h;9"
t,ation 01 NO. dec reases, atld yice "ersa. cis ely thalamount of fuel i. injecled 100the
d<:g ... 01 co.,'''' OCC"'"CY " •• ""'. by ,h.
inducted air quantity in order 10 enSure
_anced ;nc ..... in <0,1>0. mO/""id.
that. theo,etically. perfect combushon can
(CO)/usP boIo ...
I,OOpoin,... well • •
Cata lytic aftertreatment
lake place. Such an air·fuel mi. tu'e ia
by II,. ,add•• iump i. 'ho "",1.. , 01 Mtogen
(NOJ con"'n' / ""' . 1>0 ... 'ho ;' _ 1.00
charact",i.ed by lhe e.cess·air factor
;. '"' 1.00. Wilh Ihis e.cess·ai. lac tor. the
SQ," CO ond NO.~~"" .nc..
cata lytic converter operates with high e Ui·
cier.cy.
This means therelore.thattheactual dilli·
The e.haust·gas em iss ion level 01 an culty encountered when using 'catatytic
engine can be inHuenced at th,oodiHe,ent aflertreatment' hes in maintaining A at
"
points. Thel,rst possib<lity 01 influencing precisely 1.00 10' all operating modes.
~
Ihe omiasions is du,inglr.e mi.ture·lorma· because even a deviation 01 only 1')ji has
lion Slag .. before th .. engin ... Tho second consideflble adverse ellects on the afte,·
"
possibil ily is the use ot spedal design treatment. 8utt he best.Q~~
measu,es on the eng ine itsell (tor in· is ir.capable 01 holding the air·luel mi.lure
atar.ce, optimind combuSlion·chamber within such close tolerances. and the onty
shape). The lhird possibility is alterlreat· solulion is 10 apply an extremely accurate
ment ollhe e.haust gases on the e.haust ~~totheair·l ualmi.lure·
side of the engine. whereby the task is to managemenl syslem. The reason ,s that
complete the combustion 01 the luei. This althwgh an open.loop miJlure conlrol cal·
is carried OUI by means 01 a calalytic culltes and mele.s the required fuel quan·
conve"e, (Fig. 48) which has two notable tily, it does not monito, the results, One
~co
chafacleristics,
speaks 01 an S!pen co!!lro! loop, Tf>e £l2:
~~ol
themi.tur
..
ontheother
• The catalytic converter promotes tho
afterbu,ning 01 eo and He to harmless hand measures the composition 01 the
'e.haust gas and uses theresults tOCOfrect
ca,bon dio.ide (CO,) and water (H,O).
. Atthe s ame time, thecatalyticconye'ter Ihe calculated fuel quantity. This is
reduces the nilrogen 01 o.ide (NOJ to referred to as a (;(osed eon1rgJ (oop. The
nit,ogen (N) ,
Lambda oxygen sensor lacil ity inco<po,al'
-<::.~
al l
I
l! ia Ihe'elo'e perteclly clear that the cata· ed in Ihe KE·Jelronic syslemcoMerts whal
lytic allertreatment of the e.haust gas is would otherwise be an open· loop control
~,
considerably mOre eltective than lor in· into a closed·loop cont.ol , This lorm of
I
stance the purely the, mal aftcrburning 01 conlrol is particularfy effective on luel·
the e .hauat gases in a thermal reactor.
injection engines because lhey do nol
I
have the additional delay limes caused by
l.@.nga<;atalyliccon"er1er m01elhan90% the long intake paths found on carbu,etor
I.>
gltbe lo. ic substa!!Ces can b@cQ"Y@rlid engines.
e•.,...·." foelO' ;,
\0 ha'mless substances.
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Lambda closed -loop
control
Basically. tile sensor is constructed hom
an element of special ceramic. the surisee
01 which is cooted with micropo'ous
platinum electrodes. The operalion of the
SSnSor is based upon tha lactthat ceramic
male"at is porous and permits d iffusion
01 Ihe o.ygen p'esent in the air {solid
electrolyte). At higher temperatures. it
becomes conductive. and il too o'1gen
concentration on one sideol the etectrode
range 01 the is dillerem to that on the other. then a
vohage is generated belween the e lec·
trodes. In the area of stoiChiometric air·
luel mixtu ,e p. .. 1.00). a jump takes place
Operation
The sensor protrudes into the exhaust-gas in the senSOr voitago output curve. This
stream and is designed so that the outer voltage represents the measured signal
electrode is surrounded by e.haust gas. {Fig. 50).
and the inner elecl rod e is connected to t he
atmospheric air.
Const,uctlon
Th e ceramic S<)nsor body is held in a
threaded mounting and provided with a
protecli.e tube and electflcal connec'
.en.....
tions. The su rtace 01 the S<)nSOr ceramic
bod y has a microporOlJs platinum layer
which on the one side decisively in·
tluences the se n$Or chalacteristic while
on the other serving as an electrical
conlact. A highly adhesive and highly
porOlJsceramiccoating has beenapplie-d
over the platinum layer at the end 01 the
ceramic body that i~ e xposed 10 Ihe
e xllaustgas. This protective layarprevents
Ihe solid particles in the e.haust gas Irom
eroding the platinum layer.
A protective metal aleoW! is filled over the
senSOr on Ihe electrical conneclion end
and crimped to the s,,"$Or housing. This
sloe.e is provided wilh a bore to enSure
pressule compensation in the se n$O' in·
5!) PuiliOlfinll ollho t..m~d• • en ....
terior. and a lso serves as the support lor
in 0 duo. exhou .. • "lem.
the disc spring. The connection lead is
c.imped tothecontact e lement and is led
thlough an insulaling sleeve to the outside
01 the SenSOr. In order to . eep combustion
deposits in the e. haust gas away from Ihe
c<lfamic body. the end 01 the e xhaust sen·
sO< which protrudes into the e,haust'gao
flow is p'olected bya special tube having
,
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'.n''''.
52.1 Funclion oIlhe Lombdo
, S ••,,,, c.,omoe. :1 Ehtctrode.. 3 Con,"e".
4 EI.-;,,;"ol conIKr'"g ro ,he • .,."mll.
5 E,buor p'<>O. 6 P",'e<I". c&T'''''c roye'
r_.1
slots so designed thai the exhausl gas and
lhe solid particles entraIned in it do not
come into direct contact with Ihe ceramic
body.
Using the close<I-loop cont,oI circuit
lormed wilh the aid 01 the Lambda senso'.
deviations Irom a speci fied ai,·fuel ratio
can be detected and corrected. This con·
Irol principle is based upon the measure'
menl 01 100 e.haust·gas oxygen by the
Lambda senSOr. The e.haust·gas oxygen
is a measure for lhe compos ition of theair·
luel mi.ture supplie<l to the engine. The
Lambda sensor acts as a probe in the
e.hausl pipe and delivers the inlormation
as 10 wh ethel Ihe mi xtu' e is ric hel '" lea nar
than ~. 1.00.
In case 01 a deviation 110m this ~ .. 1.00
ligure. the voltageolthe sensoroutpul s ig·
nal changes ab.uplly. This pronounced
change is evalualed by the EeU which is
provided with aclosad -loopconlrol circuit
for this purpose. This inlluellCes Ihe co<·
rection 01 the injecled'luel quantity which
has been worked oul electronically by tile
KE·Jel'onic. Using this concept. it is pos si blo to control the fuel metering sO accu·
rately thatthoair·luel lalio is optimum in a ll
operating ranges independent olload and
errgine speed. Tolerances and the effects
01 engine ageing are of no importance. II.
tor instance. ~ • 1.03 (slighlly lean mi.·
tureJ.lhe Lambda conlrol circuil compen'
sates 10' this excess air by inc reasing the
amount olluel injecled.
The plOCesS is reversed it the mi.lure is
slightly rich (e.g. i. - 0.(7). Thiscontinuing
adjustment of the mi. ture to the). • t.OO
figure is the prerequisite for ensuring thai
the upst ream catalytic converter can carry
out Ihe aftertleatment 01 the e.haust gas
with ma. imum el/ICiMCy.
t.mbdo •• nsor_
I C""t""t elom.nt. , PIO,..,t;.. co"""" eI....nl. 3 SC"OO< C,,,,,'''. 4 P",'IX'''''' rub<
(• • ~.u", oitIo.I. 5 E/t:el""ol COIf"eel_. G
.,,'.09. 7 PtD'""',,,. . _ . (.,""'.""..,..: sxI.).
$3)
Qt."
6 H(><I.mg (-). 9 Ele<rtodo
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Electrical circuitry
""'0<
by the
sutile •• tor Ih" relay 10 II<! ed (lOt ,nal.nee due to .n accIdent) the
'wo'ched on. E"9,ne .tart IS $>g~led by control .et.y sWItches 011 .boot 1 second
lh, pul," from Terminal 1 of t he igMlon Ifte, the I..t ""lie " ,ecelved . ThOs ..Iely
COIl whIch ... ..aluated by tile electroniC C"';Ult thus prevents the fuel pump lrom
Du"ng c"nkong. the '11"",on and Slar,ing Cltcu.' f)' In the eoolrol relay. Upon receipt continuing to dellve. ruel when the eng"'e
sw"ell appl,,,s .ollage 10 the control ,elay ollhe Ii,., pul,,,, the! canlfol relayswilches " "",ona'} ond the ig,,;tion is switched
(Fig. !S5) wh'ch sWllches on as soon as the on and appl ies ' Gllage 10 Ihe electric fuel 0 •.
&fIg'ne tum • . Here, Ih" englne speed pump and Ihe au"liary-.i, device. If the
reached by lhe engine when it 1$ cranked pulSe! from the ignition 0";1 a,,, inlerfljpt-
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