Regenerative Braking System Print

8/13/2019 Regenerative Braking System Print

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Seminar Report on Regenerative Braking System 2013-2014

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

Dept. of Mechanical Engg. 1


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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


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

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/Brake


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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

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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


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/

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