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INTRODUCTION
Brake:-
A brake i s a machine e lement and i t s p r inc ip le ob jec t i s
t o absorb ene rgy du r i ng dece l era t ion . In veh i cl e b rakes a re
used t o abso rb k i ne t i c ene rgy whereas i n ho i s t s o r e l eva t o r s
brakes are a lso used to absorb potent ia l energy . By
connect ing the moving member to s t a t ionary f rame, normal ly
brake conver ts kinet ic energy to hea t energy. This causes
w as ta ge o f e ne rg y a nd a ls o w ea ri ng o f f ri ct i on al l in in g
mater ia l .
Regenerative Braking System:-
R eg en er at iv e B ra ki ng ys te m i s t he w ay o f s lo wi ng
vehic le by us ing the motors as brakes. Ins tead of the surp lus
e n er gy o f t he v eh ic le b ei ng w a st ed a s u n wa nt ed h e at , t h e
motors ac t as genera tors and re turn some of i t t o the overhead
wires as e lect r ic i ty .
T he v eh i cl e i s p ri ma r il y p ow e re d f r om t he e le c tr i ca l
ene rgy gene ra t ed f rom t he gene ra t o r , wh i ch bu rns gaso l i ne .
T hi s e ne rg y i s s to re d in a l ar ge b at te ry , a nd u se d b y a n
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e lec t r ic motor tha t p rovides mot ive force to the wheel s . The
regene ra t i ve ba rk i ng t ak i ng p l ace on t he veh i c l e i s a way t o
obta in more e f f i c i ency! ins tead of conver t ing k ine t i c energy
to thermal energy through f r i c t iona l b rak ing , the vehic le can
conver t a good f rac t ion of i t s k ine t i c energy back in to charge
in the bat tery, using the same principle as an al ternator .
There fore , i f you d r ive l ong d i s t ance w i thou t b rak i ng,
you" l l be poweri ng t he vehi c le en t i r el y f rom gasol i ne . The
regenerat ive braking
Regenerat ive Braking ys tem comes in to i t s own when you"re
d r i v i n g i n t h e c i t y , a n d s p e n d i n g a g o o d d e a l o f y o u r t i m e
braking .
#ou wi l l s t i l l use more fuel in the c i ty for each mi le you
dr ive than on the h ighway, though. $Thermodynamics t e l l s us
that a l l ineff ic iency comes from heat generat ion. %or instance,
when you b rake , t he b rake peda l s hea t up and a &uan t i t y o f
hea t , or energy , is los t to the out s ide wor ld . %r i c t ion in the
engine produces heat in the same way.
' ea t e ne r gy , a ls o, h as h ig h er e nt r op y t ha n , s ay , e le c tr ic ,
meaning that i t i s less ordered. (
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Defini t ion:
Braking method in which the mechanical energy from the
l oad i s conve r t ed i n to e l ect r i c energy and regene rat ed
back into the l ine is known as Regenerat ive Braking.
The )otor operates as generator .
Regenerative Braking For Hybrid e!i"#e:
In most e l ec t r i c and hybr id e l ec t r i c vehic les on the road
today , th i s i s accompl i shed by opera t ing the t rac t ion motor as
a g en er at or , p ro vi di ng b ra ki ng t or &u e t o t he w he el s a nd
recha rg ing t he t rac t ion ba t te r ie s . The ene rgy p rov ided by
r e g e n e r a t i v e b r a k i n g c a n t h e n b e u s e d f o r p r o p u l s i o n o r t o
power vehicle accessor ies .
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N$C$SSIT% OF TH$ S%ST$&
The regene ra t i ve b rak i ng sys t em de l i ve r s a number o f
s igni f icant advantages over a car that only has fr ic t ion brakes.
In low*speed , s top*and*go t ra f f i c where l i t t l e dece le ra t ion i s
r e &u ir e d! t he r e ge n er a ti ve b r ak i ng s ys te m c an p r ov i de t he
majori ty of the tota l braking force. This vast ly improves fuel
economy wi th a vehicle , and fur ther enhances the
a t t rac t iveness of vehic les us ing regenera t ive brak ing for c i ty
driving. At higher speeds, too, regenerat ive braking has been
shown t o con t r ibu te t o i mproved fue l economy + by a s much
as -.
/onsider a heavy loaded t ruck having very few s tops on
the road . I t i s opera ted near ma0imum engine e ff i c i ency . The
1 - o f t he e ne rg y p ro du ce d i s u ti li 2e d t o o ve rc om e t he
ro ll i ng and ae rodynami c road fo rces. The energy wast ed i n
a p pl yi ng b r a ke i s a b ou t . A ls o i t s b r ak e s p ec if i c f ue l
consumpt ion i s 3.
4ow consider a vehic le , which i s operated in the main
c i t y where t r a f f i c i s a ma j o r p rob l em he re one has t o app l y
brake fre&uent ly . %or such vehicles the wastage of energy by
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a p pl ic at io n o f b r a ke i s a b o ut 5 - t o 5 3 . A nd a l s o i t i s
ineff ic ient as i t s brake speci f ic fuel consumpt ion i s high.
'6A7# 89A:6: TR;/< /IT# B;
.= >raphical representation of energy usage between two vehicles.
S ome o f t !e a dv ant ag es of r eg en er at iv e b ra ki ng o ve r
"onventiona# braking are as fo# #o's:
$nergy Conservation:
The f l ywhee l abso rbs ene rgy when b rak i ng v i a a c l u t ch
sys tem slowing the car down and speeding up the wheel . To
accelerate , another c lutch system connects the f lywheel to the
dr iv e t r ain , s peed ing up the ca r an d s lowing do wn th e
Dept. of Mechanical Engg. 5
Road 1-9ther=1
Rake 53
Road5
Brake other ?
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f lywheel . 6nergy i s therefore conserved rather than wasted as
he at and l ight wh ic h i s wha t nor ma lly hap pens in the
contemporary shoe@disc system.
(ear Red)"tion:
A n e le ct ri c d ri ve t ra in a ls o a ll ow s f or r eg en er at iv e
breaking which increases 6ff ic iency and reduces wear on the
vehic le brakes . In regenera tive rak ing , when the motor i s no t
receiving power from the bat ter y pack, i t res is t s the turning of
t he whee l s , cap t u r i ng some o f t he ene rgy o f mot i on a s i f i t
were a generator and retu rning that energy to the bat tery pac k.
In mechanical brakes! lessening wear and e0tending brake l i fe
is not possible . This reduces the use of use the brake.
F)e# Cons)m*tion:
The fue l consumpt i on o f t he conven t i ona l veh i c l e s and
regene rat i ve b raki ng sys tem veh ic l es was eva lua t ed ove r a
course of var ious f i0ed urban dr iv ing schedules . The resu lt s
are compared as shown in f igure . Represent ing the s igni f icant
cos t say ing to i t s owner , i t has been proved the regenera t ive
braking i s very fuel *eff ic ient .
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Braking i s not tota# #oss:
/onvent ional brakes apply fr ic t ion to convert a vehicle"s
kinet ic energy into heat . In energy terms, therefore , brakin g i s
a t ot a l l o s s o nc e h ea t i s g en e ra te d, i t i s v er y d if fi cu lt t o
reuse . The regene ra t ive b raki ng syst em, however , s l ows a
vehicle down in a di fferent way.
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R$+$N$R,TI$ BR,IN+ S%ST$&
.
A regenerative brakeis an apparatus, a device or system which allows
a vehicleto recapture and store part of the kinetic energythat would otherwise
be lost to heatwhenbraking.
T!e I&, o*erating *rin"i*#e
'onda s pa t en t ed I) A concep t i s &u i t e s i mpl e * u se an
eff ic ient 9t to engine supplemented by an elect r ic motor when
Dept. of Mechanical Engg. 8
http://en.wikipedia.org/wiki/Vehiclehttp://en.wikipedia.org/wiki/Kinetic_energyhttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Brakehttp://en.wikipedia.org/wiki/Vehiclehttp://en.wikipedia.org/wiki/Kinetic_energyhttp://en.wikipedia.org/wiki/Heathttp://en.wikipedia.org/wiki/Brake8/13/2019 Regenerative Braking System Print
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a dd it io na l p ow er i s n ee de d. A ls o r ef er re d t o a s a hy br id
system because i t uses two power sources , the I)A concept
a ll ow s t he / iv ic ' yb ri d t o u se a s ma ll er g as ol in e e ng in e
without any significant loss in performance.
Thi s syst em i s e spec ia ll y e f fec ti ve due t o t he f act t hat
accelerat ion re&ui res a s igni f icant ly higher power than needed
f o r c r u i s i n g o n a l e v e l r o a d $ w h e r e v e h i c l e s s p e n d m o s t o f
thei r t ime( . An engine more powerful than needed has to work
under low load most of the t ime, condit ion where i ts efficiency
i s lower than under h igh loads , thus worsening the vehic le s
fuel economy..
T he e le ct ri c m ot or * ge ne ra to r p os it io ne d b et we en t he
engine and t ransmiss ion ass i s t s the engine when acce le ra t ing
a nd r ec ov er s e ne rg y t o s to re i n b at te ri es w he n b ra ki ng o r
dece le rat ing $ r egene rat i ve b rak i ng( , a l lowi ng i t t o opera te
independently without the need for a grid power supply.
C he n th e / iv ic ' yb ri d i s c oa st in g o r i ts b ra ke s a re
appl ied , i ts e l ec tr i c mot or becomes a gene rat or , conve rt ing
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fo rward momentum $k ine ti c ene rgy( i n to e l ec t r ica l ene rgy ,
i ns te a d o f w as ti n g i t a s h ea t d u ri ng c on v en ti on a l b r ak in g .
6nergy i s s tored in a ba t t e ry pack loca ted behind the rear sea t
in the t runk . I f the s t a t e of charge of the ba t t e r i es i s low, the
mo to r* ge ne ra to r w il l a ls o r ec ha rg e t he m w hi le t he / iv ic
'ybrid i s cruis ing.
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$/$&$NTS OF TH$ S%ST$&
There a re t h ree bas i c e l emen t r e&u i red wh i ch a re necessa ry
for the working of regenerat ive braking system, these are
0.$nergy Storage Unit 1$SU2:
The 6; performs two primary funct ions
=.T9 recover D store braking energy
. T 9 a b so r b e 0c e ss e n gi ne e ne r gy d ur i ng l ig ht l oa d
opera t ion The se lec t ion c r i t e r i a for an e f fec t ive energy
storage includes
=. 'igh speci f ic energy s torage densi ty
. 'igh energy t ransfer ra te
E. mal l space re&ui rement
T he e ne rg y r ec ap tu re d b y r eg en er at iv e b ra ki ng mi gh t b e
s t ored i n one o f t h ree dev ices an e l ec t rochemica l ba tt e ry, a
f lywheel , in a regenerat ive fuel cel l .
Regen and Batteries:
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Ci th t his s ys te m, t he e le ct ri c mo to r o f a c ar b ec ome s a
genera tor when the brake peda l i s appl i ed . The k ine t ic energy
of t he ca r i s u sed t o gene rat e e l ec t ri c it y t ha t i s t hen used t o
recharge the ba t t e r i es . Ci th th i s sys tem, t rad i t iona l f r i c t ion
brakes must a l so be used to ensure that the car s lows down as
much as necessary . Thus , no t a l l o f the k ine t i c energy of the
ca r can be ha rnessed fo r t he ba t t e r i e s because some o f i t i s
F los t F to was te hea t . ome energy i s a l so los t to res i s t ance as
t he e ne rg y t ra ve ls f ro m t he w he el a nd a 0l e, t hr ou gh t he
d riv et ra in a nd e le ct ri c mo to r, a nd i nt o t he b at ter y. % or
e0ampl e , t he Toyo t a G r i us can on l y r ecap t u re abou t E- of
the vehicles kinet ic energy.
T he ' o nd a I n si gh t i s a no t he r v eh i cl e i n a dd i ti o n t o t he
Gr i us t ha t i s on t he marke t and cu r ren t l y uses r egene ra t i ve
braking . In the Insight there are two decelera t ion modes
C hen t he t h ro tt l e i s engaged, bu t t he b rake peda l i s no t , t he
v eh ic le s lo ws d ow n g ra du al ly , a nd t he b at te ry r ec ei ve s a
par t ia l charge .
Chen the brake pedal i s depressed, the bat tery receives a
h igher charge , which s lows the vehic le down fas te r . The
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f ur th er t he b ra ke p ed al i s d ep re ss ed , t he mo re t he
convent ional f r ic t ion brakes are employed.
I n t he I n si gh t, t he m ot or @ ge n er a to r p r od u ce s A /, w hi ch i s
conver t ed i n to :/, wh i ch i s t hen used t o cha rge t he Ba t t e ry
)o du le . Th e I ns ig ht , a s w el l a s a ll o th er r eg en er at iv e
sys t ems , mus t have an e l ec t r i c con t ro l l e r t ha t r egu l a t e s how
much cha rge t he ba t t e ry r ece i ves and how much t he f r i c t i on
brakes are used.
Regen and F#y'!ee#s:
I n t hi s s ys te m, t he t ra ns la ti on al e ne rg y o f t he v eh ic le i s
t ra n sf er r ed i nt o r ot at io n al e n er gy i n t he f ly w he el , w h ic h
s tores the energy unt i l i t i s needed to acce le ra te the vehic le .
The benef i t o f us ing f lywheel t echnology i s tha t more of the
f o r w a r d i n e r t i a l e n e r g y o f t h e c a r c a n b e c a p t u r e d t h a n i n
ba t te r ies , because the f lywheel can be engaged even dur ing
re la t ive ly shor t in t e rva l s of brak ing and acce le ra t ion . In the
case o f ba tt e r ie s , t hey a re no t ab l e t o accep t cha rge a t t hese
r ap id i nt er va ls , a nd t hu s m or e e ne rg y i s l os t t o f ri ct io n.
Ano th er ad van tage of f ly wh eel tech nolo gy i s that th e
addi t ional power suppl ied by the f lywheel during accelerat ion
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s ub st an ti al ly s up pl em en ts t he p ow er o ut pu t o f t he s ma ll
engine that hybrid vehicles are e&uipped wi th .
3. Contin)o)s#y ariab#e Transmission 1CT2:
The energy s torage uni t re&ui res a t ransmiss ion tha t can
h a n d l e t o r & u e a n d s p e e d d e m a n d s i n a s t e e p l e s m a n n e r a n d
smoothly cont ro l energy f low to and f rom the vehic le wheel s .
%or t he f l ywheel t he con ti nuous ly va r iab l e t r ansmi ss ion and
v e hi cl e b ec a us e f ly w he e l r o ta ti on a l s pe e d i nc r ea s es w he n
vehicle speed decreases and vice versa .
% ly wh ee l c an w or k we ll w it h e ith er me ch an ic al o r
hydrostat ic cont inuously var iable t ransmission.
4. Contro# System:
A n H 9 4* 9% % e ng in e c o nt ro l s y st em i s u s ed . T ha t
means t ha t t he eng i ne i s H94 un t i l t he ene rgy s t o rage un i t
h as b ee n r ea ch ed t he d es ir ed c ha rg e c ap ac it y a nd t he n i s
decoup l ed and s t opped un t i l t he ene rgy s t o rage un i t cha rge
fal l below i t s minimum re&ui rement .
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D$SCRI5TION 6 O5$R,TION
Ho' regenerative braking system 'orks7
R eg en e ra ti ve $ or : yn a mi c B r ak in g ( o c cu r s w he n t he
vehic le i s in mot ion , such as coas t ing , t rave l ing downhi l l o r
braking . And the accelerator pedal i s not being depressed.
:ur i ng HRegen t , t he mot o r becomes a gene ra t o r and sends
energy back to the bat ter ies .
I t i s e 0p la in ed a s f ol l ows , b ec au se t he wh ee ls o f a
d e ce le r at in g v e hi cl e a r e s ti ll m ov i ng f o rw ar d , t he y c a n b e
made t o t u rn t he e l ec t r i c mot o r , wh i ch t hen feeds ene rgy t o
t he ba tt e r ie s fo r s t orage. The syst em becomes , i n e f fect , a
genera tor , which provides brak ing force whi le i t conver t s the
v eh ic le "s k in et ic e ne rg y i nt o a r eu sa bl e f or m* e le ct ri ca l
energy.
C hen t he acce l e ra t o r peda l i s r e l eased , t he absence o f
pressure t r iggers a response from the 6nergy torage ;ni t
$6;(. Regenerat ive braking begins , and the bat ter ies are re*
cha rged by t he mot or , wh ich i s t u rned by t he whee ls . In t h is
case, t he f r i ct i on b rakes a re no t engaged. I f more v igo rous
decelerat ion i s re&ui red, and the br ake pedal i s depressed, th is
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engages bo th se t s o f b rakes. 'owever, t o ma0 imi 2e ene rgy
eff i c i ency , i t i s advantageous to apply the regenera tive brake
as such as poss ib le + i t t herefore t ends to do more of i t s to t a l
work in the f i rs t par t of the brakin g mot ion.
There are two decelerat ion modes
=. %oot off throt t le but not on brake peda l + in this mode,
the charge @ass i st gauge wi l l show par t i a l charge , and the
vehicle wi l l s low down gradual ly .
. %oot on brake pedal * In this mode, a higher amount of
regenera t ion wi l l be a l lowed, and the vehic le wi l l s low
more rapidly. :uring l ight brake pedal appl icat ion, only
t he I )A mo to r@ @g en er at or i s s l ow in g t he c ar . C it h
heavier brake pedal appl icat ion, the convent ional f r ic t ion
brakes a lso come into play . Chen decelera t ing,
r egene ra t i on w i l l con t i nue u1n t i l eng i ne speed fa l l s t o
about =--- rpm. At th i s poin t , the dr iver wil l t yp ica l ly
shi f t in to neut ral .
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$8,&5/$
)ercury 'ybrid )ariner
0 . &er")ry &ar i ner H ybri d
Groduct ion Gul l ahead Groduct ion begins a
year ahead of schedule
>rowing the )ercury Brand 4ew models and goals
:ist inct ive :esign )ariner features c lean l ines , careful
craf t smanship
Gower Glay %ul l *hybrid gasol ine and elect r ic powert ra in
:ynamic /hassis 4imble handl ing and a smooth, &u iet
r ide
:ist inguished afety %ul l array of safety features
Dept. of Mechanical Engg. 17
http://63.74.120.214/adclick.php?n=abc876dfhttp://www.americancarfans.com/news.cfm/newsid/2050211.012/pageview/photo/photo/1/page/1/lang/eng/mercury/1.html8/13/2019 Regenerative Braking System Print
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>reen )ission %ord )otor /ompanys s t ra tegy for
sustainabi l i ty in vehicles
T he ) er c ur y ) ar i ne r ' yb ri d o ff e rs a u ni & ue ly s at is fy i ng
t ranspor t a ti on cho ice fo r an eve r* i ncreasi ng segmen t o f t he
populat ion concerned about the envi ronment . I t s a s ty l i sh,
u ps ca le s po rt *u ti li ty v eh ic le w ith n imb le h an dl in g a nd
i mpress i ve pe r fo rmance , a s we l l a s ampl e ca rgo and t owi ng
capac i ty . In addi t ion , i t s an envi ronmenta l ly consc ious ;7
w i t h r e m a r k a b l e f u e l e c o n o m y + a n e s t i m a t e d E E m i l e s p e r
ga l lon $mpg( c i ty , ? mpg h ighway + and i s e0pec ted to meet
t he c le an es t e mi ss io ns r at in g a ch ie va bl e b y a f os si l* fu el
v eh ic le $ /a li fo rn ia s A dv an ce d T ec hn ol og y G ar ti al J er o
6missions 7ehicle s tandard( .
6 ng in ee rs p la ce d t he a dd it io na l h yb ri d p ow er tr ai n
components low and to the rear , to lower the center of gravi ty
a n d i mp r ov e t he c on v en ti o na l ) ar i ne r s f r on t* r ea r w ei g ht
dis t r ibut ion.
The rack*and*pin ion s t eer ing i s e l ec t r ica l ly ass i s t ed , ra ther
t ha n u si ng t he t r ad it io na l hy dr au li c s te er in g p ump f or
cons i s t en t s t ee r i ng e f fo r t s and con t ro l whe t he r t he gaso l i ne
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eng i ne i s s t opped o r runn i ng . Regene ra t i ve b rak i ng uses t he
t rac t ion motor to ass i s t the four*wheel d i sc brakes in s lowing
) ar ine r 'ybri d wh il e s i mul taneous ly genera t ing e l ect r i ci t y
for charging the bat tery.
Regenerative braking of Toyota 5ri)s:
Toyo t a r ea l i 2ed t ha t one way t o ach i eve l onge r veh i c l e
r a n g e w a s t o c o n s e r v e a n d r e u s e s o m e o f t h e e n e r g y t h a t a
v e hi cl e n or ma ll y l os e s a s h ea t c au s ed b y b r ak i ng f r ic t io n .
This idea led engineers to apply the pr inciples of regenerat ive
braking .
I n a ll T oy ot a v eh ic le s t ha t f ea tu re t he r eg en er at iv e
braking system, the regenerat ive brake i s only responsible for
a par t o f the dece lera t ion necessary to s top the vehic le . In an
67, t h i s f r ac t i on i s de t e rmi ned by t he veh i c l e " s speed when
braking i s in i t ia ted. The remain ing braking force i s provided
by the vehicle "s f r ic t ion brakes . To ma0imi2e fue l economy,
o f course , t he r egene ra t i ve b rak i ng sys t em i s made t o do a s
much of the braking work as possible .
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Com*onent Used in Toyota 5ri)s f or Regenerative Braking
System:
Brake 5eda#:
I t i s used to apply braking force by the dr iver .
Hydra)# i" Booster Unit:
I t i s composed of the mas ter cy l inder and the regula tor ,
r e sponds i n t wo s t eps . % i r s t i t s i gna l s e l ec t ron i ca l l y t o t he
brake 6/; tha t braking force has been demanded. 4e0t , the
master cy l inder e0er t s hydraul i c pressure on the peda l s t roke
s im ul at or , a nd t he r eg ul at or f ee ds h yd ra ul ic f lu id t o t he
hydraul ic pressure cont rol uni t .
Brake $CU:
The b rake 6/; senses t he b rak i ng demand and sends a
f ra ct io n o f t hi s d ema nd t o t he T ' 6/ ; f or r eg en er at iv e
braking .
I t a ls o c a lc ul at e s t he f or c e n e ce ss a ry t o f ul fi ll r e ma in in g
braking demand and inst ruc t the hydraul ic pressure contro l
uni t to pass on a corresponding amount of hydraul ic f luid
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5eda# Stroke Sim)#ator:
I t absorbs an amoun t o f hydrau li c p re ssu re f rom mast e r
c yl in de r t ha t c or re sp on ds t o t he a mo un t o f b ra ki ng f or ce
appl ied by the regenerat ive braking system.
As hydraul ic pressure i s fed back to the pedal , the pedal ,
the pedal s t roke s imulator feeds back to the master cyl inder .
THS 1Toyota Hybrid System2 $CU:
I t i nduces regenera t ive brak ing , and re turns a s igna l tha t
indicates braking force output back to the brake 6/;.
Hydra)# i" 5ress)re Contro# Unit:
I t passes on a co r re spond i ng amoun t o f hydrau l i c f l u i d t o a
four way cyl inder .
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R$SU/T
Regenera t ive b raki ng t echno logy i s one more pos it i ve
s tep forward in Toyota"s &ues t to rea l i 2e the u l t imate ecocar .
B y w or k in g i n c o nc e rt w it h p re v io u sl y d ev e lo pe d e le ct r ic
moto r t echno log i es , i t s app li ca ti on he lps Toyo t a "s e l ect r i c
vehic les and hybr id vehic les $ inc luding the recent ly re l eased
pr ius( to achieve e0tended ranges and to be fr iendl ier to the
env ironmen t t han eve r be fo re . A t t he same t i me , t h i s new
technology remains unobt rus ive ly in the background! dr ivers
benefi t f rom regenerat ive brak ing whi le enjoying the same
fi rm braking feel found in convent ional ly e&uipped vehicles .
K.= Regenerative braking system using 4itinol pring
Dept. of Mechanical Engg. 22
CheelRotating :evice.
hafts.
>earbo0 /lutch pring
Cheel + A
Rotating :evice + Bhafts + /.:.
>earbo0 +6/lutch + >
pring * '
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A hydraulic regenerative braking system
improves the fuel economy of %ords %*E3-
Tonka 3*E3 during stop*and*go driving. Thesystem provides power during initial
acceleration when demand peaks.
T he '8 A s ys te m c on sis ts o f a r ev er si ble h ydr au lic
pump@motor f rom 6aton s %luid Gower >roup $6den Grai r ie ,
) 4( c ou pl ed t o t he d ri ve s ha ft t hr ou gh a c lu tc h a nd t wo
accumulators . As the dr iver s teps on the brake, the
pump@motor forces hydraul ic f luid out of a low*pressure
accumula tor and in to a h igh*pressure accumula tor , increas ing
the pressure of ni t rogen gas s tored there to 3 ,--- psi .
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:uring acce le ra t ion , the '8A sys tem swi tches f rom the
pump mode to the motor mode, the n i t rogen gas forces the
hydrau l i c f l u i d back i n t o t he l ow*pressu re accumul a t o r , and
t he pump@ mot o r app l i e s t o r&ue t o t he d r i vesha f t t h rough t he
c l u t ch . I f &u i ck acce l e ra t i on i s r e&u i red , t he % *E3- s d i e se l
engine works wi th the '8A system
The hydrau l i c l aunch a s s i s t sys t em i n t he % *E3- Tonka
funct ions as a secondary source of energy dur ing peak power
demand. I t consis t s of a low*pr essure accumulator in blue, and
a h ig h* pr es su re a cc um ul at or i n r ed . T he s ys te m c ap tu re s
energy normal ly d i ss ipa ted as hea t dur ing breaking , s tores i t ,
and uses i t la ter during per iods of peak power demand.
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6ighty percent of the ini t ia l k inet ic energy i s re turned to
t he v eh ic le . F Th e s ys te m s to re s a pp ro 0i ma te ly E 1- k L o f
e n er gy , F s a ys B r ad B o hl ma nn , a m ec ha n ic a l e ng in e er a nd
business development coordina tor in Advanced Technology a t
6aton s % lu id Gower >roup. FCi th tha t much energy , we can
acce lerate a =- ,---* lb vehic le f rom a dead s top to be tween 3
and E- mi l e s pe r hour w i t h no a s s i s t ance f rom t he veh i c l e s
combust ion engine.F
F%ord thinks that both e lect r ic and hydraul ic regenerat ive
sys tems have a fu ture ,F says Lohn Brevick , a %ord mechanica l
engineer working on the '8A sys tem. FBut for heavy vehic les
l ik e o ur = -, -- -* lb % *E 3- t ru ck s, h yd ra ul ic s a re b et te r a t
captur ing lost energy than elect r ic systems.F
6 at on s B oh lm an n e 0p l ai ns t ha t t he r e al a d va nt a ge o f
hydrau li c s i s i n i t s power dens i ty . F'ydrau li c s i s capab l e o f
t ransfer r ing energy very &uick ly , F says Bohlmann. FThe ra te
o f ene rgy t r ans fer i s i n a hybr i d e l ec t ri c sys t em o f a s i mi l ar
s i2e i s much lower.F
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B oh lm an n a dd s t ha t t he s pe ci fi c v oc at io n o r d ri vi ng
cycle of the vehic le de te rmines whether a hybr id hydraul i c or
hybrid e lect r ic system is best sui ted for the vehicle . FThink of
hydrau l i c s a s a sp r i n t e r , p rov i d i ng fa s t bu r s t s o f power , F he
says. FAn elect r ic hybrid i s more l ike a marathon runner .F
FThe cha l l enge now i s t o make use o f t he r egene ra t i ve
braking system seamless to the customer ,F says %ord s
Brev i ck . FC e s t i l l have room fo r i mprovemen t s and fee l t he
'8A system has a lot of potent ia l . F
As for the future , %ord, 6a ton, and the ;. .
6nvironmenta l Grotec t ion Agency $6GA( are joint ly
conduc t i ng r e sea rch on hydrau l i c hybr i d veh i c l e s , i nc l ud i ng
i nt er n al c o mb u st io n e ng in e s t ha t w ou ld p ro d uc e h y dr a ul ic
pressure to dr ive the vehicle . 6aton s igned both a technology
l icense agreement and a cooperat ive research and development
a gr ee me nt w it h t he 6 GA f or t he d ev el op me nt o f f ut ur e
generat ion systems.
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This i s l ike i f you were in a boa t a t a dock , and you grabbed
the dock and p ush ed wi th y our ar m. The f or ce yo u ar e
genera t ing i s movi ng t he boa t r e l at i ve t o t he l oca t ion o f t he
dock. The more fo rce you app l y , t he f a s t you ge t t he boat t o
move.
Fri"t ion in Hybrids
There i s f r i c t ion everywhere in the hybr id sys tem. There
i s e l ec t r i ca l f r i c t ion be tween the a toms and e lec t rons moving
i n t he w i re s be t ween t he ba t t e ry and t he mot o r and t h rough
t he mo to r i ts el f. T he re i s m ag ne ti c f ri ct io n i n t he me ta l
laminat ions that make up the magnet ic c i rcu i t of the motor , as
wel l as in the magnet s aga in on the a tomic l eve l . Then , there
i s mechanica l f r i c t ion be tween every moving par t , such as the
bear ings, seals , gears , cha ins and so on. The by*product of
f r i ct i on i s hea t . Take your hands rub t hem t oge t he r and your
pa lms get warm. The faster you do i t , the faster they heat up.
Also, the harder they are pressed together , the fa ster they wi l l
hea t . %r i c t ion i s energy los t to hea t . Chen a l l o f these losses
a r e a d d e d u p , t h a t i s w h a t d e t e r m i n e s t h e e f f i c i e n c y o f t h e
vehicle .
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Fri"t iona# /osses in Conventiona# Cars
A s t anda rd ca r genera t es t o r&ue t o move t he wheel s t o
d riv e t he v eh ic le d own t he r oa d. : ur in g t his t i me , i t is
g en er at in g f ri ct io n a nd l os se s. C he n y ou a pp ly s ta nd ar d
brakes , i t i s just another f r ic t ion device that has special ly
des i gned ma t e r i a l t o hand l e t he hea t f rom f r i c t i on , wh i ch i s
a pp li ed t o t he d ru ms a nd r ot or s t ha t s to p t he w he el f ro m
turn ing . The f r i c t ion be tween the wheel and the ground s tops
t he v eh ic l e. T hi s s ta n da r d v eh ic l e h a s f r ic ti o na l l os s es t o
move the vehic leOand uses the fundamenta l behind f r i c t iona l
losses to s top the vehicle . o i t "s a lose* lose s i tuat ion.
Transferring Tor)e Ba"k to t!e &otor
Thi s iner t ia i s the fundamenta l p roper ty of phys ics tha t
i s u sed t o r ec l a i m ene rgy f rom t he veh i c l e . In s t ead o f u s i ng
=-- of t he founda t i on b rakes o f t he veh i c l e , wh i ch a re t he
f r i c t i o n b r a k e s , w e n o w l e t t h e l i n k a g e s b a c k t o t h e m o t o r
such as the dr ive shaf t s , cha ins , and gears t ransfer the to r&ue
from the wheel s back in to the motor shaf t . 9ne of the un i&ue
th ings about most e l ec t r i c motors i s tha t e l ec t r i cal energy can
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be t ransfer red into mechanical energy and a lso mechanical
energy can be t ransfer red back in to e l ec t r i ca l energy . In bo th
cases , th is can be done very eff ic ient ly .
T hu s, t hr o ug h t he t ec hn o lo gy o f t he m ot or a n d m ot o r
c o nt ro ll er , t he f o rc e a t t h e w he el s b e co me s t or & ue o n t he
e l ec t r i c mot o r sha f t . The magne t s on t he sha f t o f t he mot o r
$cal led the rotorOthe moving part of the motor( move past the
e lec t r i c co i l s on the s t a tor $ the s t a t ionary par t o f the motor(
passing the magnet ic f ie lds of the magnets th rough the coi l s
producing elec tr ic i ty . This e lect r ic i ty becomes e lect r ical
ene rgy , wh i ch i s pumped back t o t he ba t t e ry . Th i s , i n t u rn ,
cha rges t he hybr i d ba t t e ry pack . Th i s i s where t he comment
Hregenerat ion or Hreclaiming energy comes from.
That i s the bas ics of how regenera tion works . 'ow much
energy you can rec la im depends on a lo t o f fac tors . There a re
d i ff e ren t r egene rat i on t heo r i es and des igns, wh ich fa l l i n to
t wo g r ou p s o ne b e in g c a ll ed p a ra l le l r e ge n a n d t he o th e r
ca l l ed ser i es regen , which a re d i f fe ren t f rom the para l l e l and
se rie s hy br ids . Thes e r ege n g roups s t r ic t ly a re d esign
t op o lo gi es f or b r ak in g s y st em s. I t a ls o m at te r s h ow m an y
wheel s you are us ing to rec la im energy . )ost vehic les to da te
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are f ron t wheel dr ive so you can only rec la im energy f rom the
f ront wheel s . The back wheel s s t i l l was te energy to s t andard
fr ic t ion brakes unless they are somehow connected back to the
e lec t r ic motor . The o ther fac tor i s ba t t e ry s t a t e of charge and
how hard can you dr ive that energy back into the bat tery.
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CONC/USION
T he or et ic al i nv es ti ga ti on s o f a r eg en er at iv e b ra ki ng
system show about 3 saving in fuel co nsumpt ion.
The l ower ope ra t i ng and env i ronmen t cos t s o f a veh i c l e
w it h r eg en er at iv e b ra ki ng s ys te m s ho uld ma ke i t mo re
at t ract ive than a convent ional one. The t radi t ional cost of the
system could be recovered in the few years only.
The e0haus t emiss i on o f veh ic l e us i ng t he r egene rat i ve
braking concept would be much less than e&uiva lent
convent ional vehicles as less fuel are used for consumpt ion.
T he se s ys te ms a re p ar ti cu la rly s ui ta bl e i n d ev el op in g
coun t r i e s such a s Ind i a where buses a re t he p re fe r red means
of t ransporta t ion wi thin the c i t ies .
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BIB/IO+R,5H%
=( +enera# &otors (ebsi te 1 '''.gm."om2.
3 2 ' ' '. sae . org
4 2 ' '' .g oo g# e. "o m
http://www.gm.com/http://www.gm.com/Recommended