23291564 regenerative braking system

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					                                    A
                        SEMINAR REPORT ON
                  REGENERATIVE BRAKING SYSTEM




SUBMITTED BY:                                   GUIDED BY: -


ACKNOWLEDGEMENT


     This acknowledgement is a humble attempt to earnestly thank all
those who were directly or indirectly invol ved in preparation of this
seminar report.


     In particular I am thankful to m y guide Mr. Kalpesh D. Mania
who guide me in my seminar work. I am thankful to him for taking
active part in the preparation of m y seminar report. It was impossible
to present this report without his co -operation and suggestion.
      Last but not least I would like to express out deep sense of
gratitude   to   all   the   faculty   members   of   Mechanical   Engineering
Department and also my friends who help me to accomplish what I have
started for.




      DEPARTMENT OF MECHANICAL ENGINEERING


                        THE SEMINAR REPORT ON :

         REGENERATIVE BRAKING SYSTEM
                                 PREPARED BY:


                                  GUIDED BY:


    EXAMINER                                                   H.O.D
(1) ___________________
(2) ___________________
(3) ___________________
(4) ___________________




ABSTRACT

R e g e n e r a t i v e B r a k i n g S ys t e m i s t h e w a y o f s l o w i n g v e h i c l e b y u s i n g
the motors as brakes.                    Instead of the surplus energy of the vehicle
being wasted as unwanted heat, the motors act as generators and return
s o m e o f i t t o t h e o v e r h e a d w i r e s a s e l e c t r i c i t y.
The vehicle is primarily powered from the electrical energy generated
from the generator, which burns gasoline.                                  This energy is stored in a
l a r g e b a t t e r y, a n d u s e d b y a n e l e c t r i c m o t o r t h a t p r o v i d e s m o t i v e f o r c e
to the wheels. The regenerative barking taking place on the vehicle is
a w a y t o o b t a i n m o r e e f f i c i e n c y; i n s t e a d o f c o n v e r t i n g k i n e t i c e n e r g y
to thermal energy through frictional braking, the vehicle can convert a
g o o d f r a c t i o n o f i t s k i n e t i c e n e r g y b a c k i n t o c h a r g e i n t h e b a t t e r y,
using the same principle as an alternator.
LIST OF FIGURES

Fig. 1   G r a p h i c a l r e p r e s e n t a t i o n o f e n e r g y u s a g e b e t w e e n t w o v e h i c l e s.


Fig. 2    Mercury Hybrid Mariner

Fig. 3    R e g e n e r a t i v e B r a k i n g S ys t e m U s i n g N i t i n o l S p r i n g .
                       CONTENTS



1. INTRODUCTION

2. NECESSITY OF THE SYSTEM

3. REGENRATIVE BRAKE

4. ELEMENTS OF THE SYSTEM

5. DESCRIPTION & OPERATION

6. RESULTS

7. CONCLUSION
CHAPTER 1: INTRODUCTION



Brake:-
         A brake is a machine element and its principle object is to absorb
energy during deceleration.                         In vehicle brakes are used to absorb
kinetic energy whereas in hoists or elevators brakes are also used to
absorb         potential       e n e r g y.     By      connecting          the     moving         member          to
stationary frame, normally brake converts kinetic energy to heat
e n e r g y.   This causes wastage of energy and also wearing of frictional
lining material.
Regenerative Braking System: -
         R e g e n e r a t i v e B r a k i n g S ys t e m i s t h e w a y o f s l o w i n g v e h i c l e b y
using the motors as brakes.                          Instead of the surplus energy of the
vehicle being wasted as unwanted heat, the motors act as generators
and return some of it to the overhead wires as electricity.
The vehicle is primarily powered from the electrical energy generated
from the generator, which burns gasoline.                                 This energy is stored in a
l a r g e b a t t e r y, a n d u s e d b y a n e l e c t r i c m o t o r t h a t p r o v i d e s m o t i v e f o r c e
to the wheels. The regenerative barking taking place on the vehicle is
a w a y t o o b t a i n m o r e e f f i c i e n c y; i n s t e a d o f c o n v e r t i n g k i n e t i c e n e r g y
to thermal energy through frictional braking, the vehicle can convert a
g o o d f r a c t i o n o f i t s k i n e t i c e n e r g y b a c k i n t o c h a r g e i n t h e b a t t e r y,
using the same principle as an alternator.
         T h e r e f o r e , i f yo u d r i v e l o n g d i s t a n c e w i t h o u t b r a k i n g , yo u ’ l l b e
powering the vehicle entirely from gasoline. The regenerative braking
R e g e n e r a t i v e B r a k i n g S ys t e m c o m e s i n t o i t s o w n w h e n y o u ’ r e 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 yo u r t i m e b r a k i n g .
 Y o u w i l l s t i l l u s e m o r e f u e l i n t h e c i t y f o r e a c h m i l e yo u d r i v e t h a n o n
t h e h i g h w a y, t h o u g h . ( T h e r m o d yn a m i c s t e l l s u s t h a t a l l i n e f f i c i e n c y
c o m e s f r o m h e a t g e n e r a t i o n . F o r i n s t a n c e , w h e n yo u b r a k e , t h e b r a k e
p e d a l s h e a t u p a n d a q u a n t i t y o f h e a t , o r e n e r g y, i s l o s t t o t h e o u t s i d e
w o r l d . F r i c t i o n i n t h e e n g i n e p r o d u c e s h e a t i n t h e s a m e w a y.
 Heat       energy,         also,       has      higher        entropy         than,       say,       electric,
meaning that it is less ordered.)
Definition:
         Braking method in which the mechanical energy from the load is
         converted into electric energy an d regenerated back into the line
         is known as Regenerative Braking.                                  The Motor operates as
         generator.
Regenerative Braking For Hybrid Vehicle:
         I n m o s t e l e c t r i c a n d h yb r i d e l e c t r i c v e h i c l e s o n t h e r o a d t o d a y,
this is accomplished by operating the traction motor as a generator,
providing braking torque to the wheels and recharging the traction
batteries.        The energy provided by regenerative braking can then be
used for propulsion or to power vehicle accessories.
CHAPTER 2: NECESSITY OF THE SYSTEM
     T h e r e g e n e r a t i v e b r a k i n g s ys t e m d e l i v e r s a n u m b e r o f s i g n i f i c a n t
advantages over a car that only has friction brakes.                                        In low -speed,
stop-and-go           traffic       where          little       deceleration         is     required;         the
r e g e n e r a t i v e b r a k i n g s ys t e m c a n p r o v i d e t h e m a j o r i t y o f t h e t o t a l
braking force.           This vastly improves fuel economy with a vehicle, and
further enhances the attractiveness of vehicles using regenerative
braking for city driving.                  At higher speeds, too, regenerative braking
has been shown to contribute to improved fuel economy – by as much
as 20%.
         Consider a heavy loaded truck having very few stops on the road.
I t i s o p e r a t e d n e a r m a x i m u m e n g i n e e f f i c i e n c y. T h e 8 0 % o f t h e e n e r g y
p r o d u c e d i s u t i l i z e d t o o v e r c o m e t h e r o l l i n g a n d a e r o d yn a m i c r o a d
forces.       T h e e n e r g y w a s t e d i n a p p l yi n g b r a k e i s a b o u t 2 % .          Also its
brake specific fuel consumption is 5%.
         Now consider a vehicle, which is operated in the main city where
t r a f f i c i s a m a j o r p r o b l e m h e r e o n e h a s t o a p p l y b r a k e f r e q u e n t l y. F o r
such vehicles the wastage of energy by application of brake is about
60% to 65%.               And also it is inefficient as its brake specific fuel
consumption is high.


                Road 80%                                           Rake 65%


                                           Other
                                           18%                              Road
                                                                            26%


                                     Brake 2%        other 9%



HEAVY LOADED TRUCK                                                         CITY BUS


           2.1 Graphical representation of energy usage between two vehicles.
S o me        of     the       advantages                of   regenerative               b r a ki n g         over
c o n v e n t i o n a l b r a ki n g a r e a s f o l l o w s :
Energy Conservation:
T h e f l yw h e e l a b s o r b s e n e r g y w h e n b r a k i n g v i a a c l u t c h s y s t e m s l o w i n g
the car down and speeding up the wheel. To accelerate, another clutch
s ys t e m c o n n e c t s t h e f l yw h e e l t o t h e d r i v e t r a i n , s p e e d i n g u p t h e c a r
a n d s l o w i n g d o w n t h e f l yw h e e l .       Energy is therefore conserved rather
than wasted as heat and light which is what normally happens in the
c o n t e m p o r a r y s h o e / d i s c s ys t e m .
Wear Reduction:
An electric drive train also allows for regenerative breaking which
increases Efficiency and reduces wear on the vehicle brakes.                                                    In
regenerative raking, when the motor is not receiving power from the
battery pack, it resists the turning of the wheels, capturing some of the
energy of motion as if it were a generator and returning that energy to
the battery pack.               In mechanical brakes; lessening wear and extending
brake life is not possible. This reduces the use of use the brake.
Fuel Consumption:
The fuel consumption of the conventional vehicles and regenerative
b r a k i n g s ys t e m v e h i c l e s w a s e v a l u a t e d o v e r a c o u r s e o f v a r i o u s f i x e d
urban driving schedules. The results are compared as shown in figure.
R e p r e s e n t i n g t h e s i g n i f i c a n t c o s t s a yi n g t o i t s o w n e r , i t h a s b e e n
proved the regenerative braking is very fuel -efficient.
Braking is not total loss:
Conventional brakes apply friction to convert a vehicle’s kinetic
energy into heat. In energy terms, therefore, braking is a total loss:
once heat is generated, it is very difficult to reuse.                                  The regenerative
b r a k i n g s ys t e m , h o w e v e r , s l o w s a v e h i c l e d o w n i n a d i f f e r e n t w a y.
CHAPTER 3 :REGENERATIVE BRAKING SYSTEM
                                                          .

A regenerative brake is an apparatus, a device or system which allows a vehicle to
recapture and store part of the kinetic energy that would otherwise be 'lost' to heat when
braking.



The IMA operating principle




Honda's patented IMA concept is quite simple - use an efficient Otto
engine supplemented by an electric motor when additional power is
n e e d e d . A l s o r e f e r r e d t o a s a ' h yb r i d ' s ys t e m b e c a u s e i t u s e s t w o p o w e r
s o u r c e s , t h e IM A c o n c e p t a l l o w s t h e C i v i c H yb r i d t o u s e a s m a l l e r
gasoline engine without any significant loss in performance.



T h i s s ys t e m i s e s p e c i a l l y e f f e c t i v e d u e t o t h e f a c t t h a t a c c e l e r a t i o n
requires a significantly higher power than needed for cruising on a level
road (where vehicles spend most of their time). An engine more
powerful than needed has to work under low load most of the time,
condition where its efficiency is lower than under high loads, thus
w o r s e n i n g t h e v e h i c l e ' s f u e l e c o n o m y. .
The electric motor-generator positioned between the engine and
transmission assists the engine when accelerating and recovers energy to
store in batteries when braking or decelerating (regenerative braking),
allowing it to operate independently without the need for a grid power
s u p p l y.

W h e n t h e C i v i c H yb r i d i s c o a s t i n g o r i t s b r a k e s a r e a p p l i e d , i t s e l e c t r i c
motor becomes a generator, converting forward momentum (kinetic
e n e r g y) i n t o e l e c t r i c a l e n e r g y, i n s t e a d o f w a s t i n g i t a s h e a t d u r i n g
conventional braking. Energy is stored in a battery pack located behind
the rear seat in the trunk. If the state of charge of the batteries is low,
t h e m o t o r - g e n e r a t o r w i l l a l s o r e c h a r g e t h e m w h i l e t h e C i v i c H yb r i d i s
cruising.
CHAPTER 4: ELEMENTS OF THE SYSTEM

There are three basic element required which are necessary for the
w o r k i n g o f r e g e n e r a t i v e b r a k i n g s ys t e m , t h e s e a r e :
1.Energy Storage Unit (ESU):
The ESU performs two primary functions
1.TO recover & store braking energy
2. TO absorb excess engine energy durin g light load operation
         The selection criteria for an effective energy storage includes
1. High specific energy storage density
2. High energy transfer rate
3. Small space requirement
The energy recaptured by regenerative braking might be stored in one
of    three       devices:         an      electrochemical               b a t t e r y,   a   flywheel,          in     a
regenerative fuel cell.


Regen and Batteries :

W i t h t h i s s ys t e m , t h e e l e c t r i c m o t o r o f a c a r b e c o m e s a g e n e r a t o r w h e n
the brake pedal is applied. The kinetic energy of the car is used to
generate electricity that is then used to recharge the batteries. With
t h i s s ys t e m , t r a d i t i o n a l f r i c t i o n b r a k e s m u s t a l s o b e u s e d t o e n s u r e t h a t
t h e c a r s l o w s d o w n a s m u c h a s n e c e s s a r y. T h u s , n o t a l l o f t h e k i n e t i c
energy of the car can be harnessed for the batteri es because some of it
is "lost" to waste heat. Some energy is also lost to resistance as the
energy travels from the wheel and axle, through the drivetrain and
e l e c t r i c m o t o r , a n d i n t o t h e b a t t e r y. F o r e x a m p l e , t h e T o y o t a P r i u s c a n
o n l y r e c a p t u r e a b o u t 3 0 % o f t h e v e h i c l e s k i n e t i c e n e r g y.

The Honda Insight is another vehicle in addition to the Prius that is on
the market and currently uses regenerative braking. In the Insight there
are two deceleration modes: When the throttle is engaged, but the
b r a k e p e d a l i s n o t , t h e v e h i c l e s l o w s d o w n g r a d u a l l y, a n d t h e b a t t e r y
receives a partial charge.

        When the brake pedal is depressed, the battery receives a higher
         charge, which slows the vehicle down faster. The further the
         brake pedal is depressed, the more the conv entional friction
         b r a k e s a r e e m p l o ye d .

In the Insight, the motor/generator produces AC, which is converted
into DC, which is then used to charge the Battery Module. The Insight,
a s w e l l a s a l l o t h e r r e g e n e r a t i v e s ys t e m s , m u s t h a v e a n e l e c t r i c
controller that regulates how much charge the battery receives and how
much the friction brakes are used.

Regen and Flywheels:

I n t h i s s ys t e m , t h e t r a n s l a t i o n a l e n e r g y o f t h e v e h i c l e i s t r a n s f e r r e d
i n t o r o t a t i o n a l e n e r g y i n t h e f l yw h e e l , w h i c h s t o r e s t h e e n e r g y u n t i l i t
i s n e e d e d t o a c c e l e r a t e t h e v e h i c l e . T h e b e n e f i t o f u s i n g f l yw h e e l
technology is that more of the forward inertial energy of the car can be
c a p t u r e d t h a n i n b a t t e r i e s , b e c a u s e t h e f l yw h e e l c a n b e e n g a g e d e v e n
during relatively short intervals of braking and acceleration. In the
case of batteries, they are not able to accept charge at these rapid
intervals, and thus more energy is lost to friction. Another advantage
o f f l yw h e e l t e c h n o l o g y i s t h a t t h e a d d i t i o n a l p o w e r s u p p l i e d b y t h e
f l yw h e e l   during        acceleration           substantially           supplements             the        power
o u t p u t o f t h e s m a l l e n g i n e t h a t h yb r i d v e h i c l e s a r e e q u i p p e d w i t h .
2. Continuously Variable Transmission (CVT):


         The energy storage unit requires a transmission that can handle
torque and speed demands in a s teeples manner and smoothly control
energy flow to and from the vehicle wheels.                                  F o r t h e f l yw h e e l t h e
continuously          variable        transmission          and     vehicle        because       f l yw h e e l
rotational speed increases when vehicle speed decreases and vice
versa.
         F l yw h e e l c a n w o r k w e l l w i t h e i t h e r m e c h a n i c a l o r h y d r o s t a t i c
continuously variable transmission.


3. Control System:
         A n “ O N - O F F ” e n g i n e c o n t r o l s ys t e m i s u s e d . T h a t m e a n s t h a t t h e
engine is “ON” until the energy storage unit has been reached the
desired charge capacity a nd then is decoupled and stopped until the
energy storage unit charge fall below its minimum requirement.
C H A PT E R5 : DESCRIPTION & OPERATION
How regenerative braking system works?
R e g e n e r a t i v e ( o r D yn a m i c B r a k i n g ) o c c u r s w h e n t h e v e h i c l e i s i n
motion, such as coasting, traveling downhill or braking.                                                   And the
accelerator pedal is not being depressed.                                 During “Regent,” the motor
becomes a generator and sends energy back to the batteries.
          It is explained as follows, because the wheels of a decelerating
vehicle are still moving forward, they can be made to turn the electric
motor, which then feeds energy to the batteries for storage.                                                       The
s ys t e m b e c o m e s , i n e f f e c t , a g e n e r a t o r , w h i c h p r o v i d e s b r a k i n g f o r c e
while it converts the vehicle’s kinetic energy into a r eusable form-
e l e c t r i c a l e n e r g y.
          When the accelerator pedal is released, the absence of pressure
triggers a response from the Energy Storage Unit (ESU).                                             Regenerative
braking begins, and the batteries are re -charged by the motor, which is
turned b y the w heels. In this case, the friction brakes are not engaged.
If more vigorous deceleration is required, and the brake pedal is
depressed, this engages both sets of brakes.                                      However, to maximize
e n e r g y e f f i c i e n c y, i t i s a d v a n t a g e o u s t o a p p l y t h e r e g e n e r a t i v e b r a k e a s
such as possible – it therefore tends to do more of its total work in the
first part of the braking motion.
There are two deceleration modes:
1. Foot off throttle but not on brake pedal – in this mode, the
charge/assist gauge will show partial charge, and the vehicle will slow
d o w n g r a d u a l l y.
2. Foot on brake pedal - In this mode, a higher amount of regeneration
will be allowed, and the vehicle will slow more rapidly.                                   During light
brake pedal application, only the IM A motor//generator is slo wing the
car.      With heavier brake pedal application, the conventional friction
b r a k e s a l s o c o m e i n t o p l a y. W h e n d e c e l e r a t i n g , r e g e n e r a t i o n w i l l
continue u8ntil engine speed falls to about 1000 rpm.                                   At this point,
t h e d r i v e r w i l l t yp i c a l l y s h i f t i n t o n e u t r a l .
                                                    EXAMPLE




                                    Mercury Hybrid Mariner


    1. Mercury Mariner Hybrid
     P r o d u c t i o n P u l l a h e a d : P r o d u c t i o n b e g i n s a ye a r
       ahead of schedule
     Growing the Mercury Brand: New models and goals
     Distinctive Design: Mariner features clean lines, careful
       craftsmanship
     P o w e r P l a y: F u l l - h y b r i d g a s o l i n e a n d e l e c t r i c p o w e r t r a i n
     D yn a m i c C h a s s i s : N i m b l e h a n d l i n g a n d a s m o o t h , q u i e t r i d e
     D i s t i n g u i s h e d S a f e t y: F u l l a r r a y o f s a f e t y f e a t u r e s
     Green Mission: Ford Motor Company's strategy for sustainability
       in vehicles

T h e M e r c u r y M a r i n e r H yb r i d o f f e r s a u n i q u e l y s a t i s f yi n g
transportation choice for an ever -increasing segment of the population
c o n c e r n e d a b o u t t h e e n v i r o n m e n t . I t ' s a s t yl i s h , u p s c a l e s p o r t - u t i l i t y
vehicle with nimble handling and impressive performance, as well as
a m p l e c a r g o a n d t o w i n g c a p a c i t y. I n a d d i t i o n , i t ' s a n e n v i r o n m e n t a l l y
conscious SUV with remarkable fuel economy – an estimated 33 miles
p e r g a l l o n ( m p g ) c i t y, 2 9 m p g h i g h w a y – a n d i s e x p e c t e d t o m e e t t h e
cleanest emissions rating achievable by a fossil -fuel vehicle
(California's Advanced Technology Partial Zero Emissions Vehicle
standard).
E n g i n e e r s p l a c e d t h e a d d i t i o n a l h yb r i d p o w e r t r a i n c o m p o n e n t s l o w a n d
to the rear, to lower the center of gravity and improve the conventional
Mariner's front-rear weight distribution.

The rack-and-pinion steering is electrically assisted, rather than using
t h e t r a d i t i o n a l h yd r a u l i c s t e e r i n g p u m p f o r c o n s i s t e n t s t e e r i n g e f f o r t s
and control whether the gasoline engine is stopped or running.
Regenerative braking uses the traction motor to assist the four -wheel
d i s c b r a k e s i n s l o w i n g M a r i n e r H yb r i d w h i l e s i m u l t a n e o u s l y g e n e r a t i n g
e l e c t r i c i t y f o r c h a r g i n g t h e b a t t e r y.



        Regenerative braking of Toyota Prius:
         T o yo t a r e a l i z e d t h a t o n e w a y t o a c h i e v e l o n g e r v e h i c l e r a n g e w a s
to conserve and reuse some of the energy that a vehicle normally loses
as heat caused by braking frict ion.                              This idea led engineers to apply
the principles of regenerative braking.
         I n a l l T o yo t a v e h i c l e s t h a t f e a t u r e t h e r e g e n e r a t i v e b r a k i n g
s ys t e m , t h e r e g e n e r a t i v e b r a k e i s o n l y r e s p o n s i b l e f o r a p a r t o f t h e
deceleration necessary to stop the vehicle.                                    I n an EV, this fraction is
determined by the vehicle’s speed when braking is initiated.                                                          The
remaining braking force is provided by the vehicle’s friction brakes.
T o m a x i m i z e f u e l e c o n o m y, o f c o u r s e , t h e r e g e n e r a t i v e b r a k i n g s ys t e m
is made to do as much of the braking work as possible.
Component Used in Toyota Prius for Regenerative Braking System:


Brake Pedal:
It is used to appl y braking force b y the driver.
Hydraulic Booster Unit:
I t i s c o m p o s e d o f t h e m a s t e r c yl i n d e r a n d t h e r e g u l a t o r , r e s p o n d s i n
two steps. First it signals electronically to the brake ECU that braking
force has been demanded.                         N e x t , t h e m a s t e r c yl i n d e r e x e r t s h yd r a u l i c
pressure           on   the     pedal        stroke       simulator,           and      the     regulator      feeds
h yd r a u l i c f l u i d t o t h e h yd r a u l i c p r e s s u r e c o n t r o l u n i t .
Brake ECU:
The brake ECU senses the braking demand and sends a fraction of this
demand to the THSECU for regenerative braking.
It also calculates the force necessary to fulfill remaining braking
d e m a n d a n d i n s t r u c t t h e h yd r a u l i c p r e s s u r e c o n t r o l u n i t t o p a s s o n a
c o r r e s p o n d i n g a m o u n t o f h yd r a u l i c f l u i d
Pedal Stroke Simulator:
I t a b s o r b s a n a m o u n t o f h yd r a u l i c p r e s s u r e f r o m m a s t e r c yl i n d e r t h a t
corresponds to the amount of braking force applied by the regenerative
b r a k i n g s ys t e m .
          A s h yd r a u l i c p r e s s u r e i s f e d b a c k t o t h e p e d a l , t h e p e d a l , t h e
p e d a l s t r o k e s i m u l a t o r f e e d s b a c k t o t h e m a s t e r c yl i n d e r .




THS (Toyota Hybrid System) ECU:
It induces regenerative braking, and returns a signal that indicates
braking force output back to the brake ECU.
Hydraulic Pressure Control Unit:
I t p a s s e s o n a c o r r e s p o n d i n g a m o u n t o f h yd r a u l i c f l u i d t o a f o u r w a y
c yl i n d e r .
C H A PT E R 6 : RE S U L T
         Regenerative             braking         technology           is    one      more        positive       step
f o r w a r d i n T o yo t a ’ s q u e s t t o r e a l i z e t h e u l t i m a t e e c o c a r . B y w o r k i n g i n
concert with previously developed electric motor technologies, its
application          helps       T o yo t a ’ s    electric        vehicles        and      hybrid        vehicles
(including the recently released prius) to achieve extended ranges and
to be friendlier to the environment than ever befo re. At the same time,
this new technology remains unobtrusively in the background; drivers
b e n e f i t f r o m r e g e n e r a t i v e b r a k i n g w h i l e e n j o yi n g t h e s a m e f i r m b r a k i n g
feel found in conventionally equipped vehicles.




                                            Wheel
                                                                            Wheel – A
                                           Rotating Device.                 Rotating Device – B
                                                                            Shafts – C.D.
                                                                            Gearbox –E
                                                                            Clutch – G
                                                                            Spring - H
                                       Shafts.




  Gearbox                                      Clutch                  Spring



                     7.1 Regenerative braking system using Nitinol Spring
                       A hydraulic regenerative braking system improves the fuel
                       economy of Ford's F-350 Tonka 25-35% during stop-and-go
                       driving. The system provides power during initial acceleration
                       when demand peaks.
T h e H L A s ys t e m c o n s i s t s o f a r e v e r s i b l e h yd r a u l i c p u m p / m o t o r f r o m
Eaton's Fluid Power Group (Eden Prairie, MN) coupled to the drive
shaft through a clutch and two accumulators. As the driver steps on the
b r a k e , t h e p u m p / m o t o r f o r c e s h yd r a u l i c f l u i d o u t o f a l o w - p r e s s u r e
accumulator and into a high -pressure accumulator, increasing the
pressure of nitrogen gas stored there to 5,000 psi.

D u r i n g a c c e l e r a t i o n , t h e H L A s ys t e m s w i t c h e s f r o m t h e p u m p m o d e t o
t h e m o t o r m o d e , t h e n i t r o g e n g a s f o r c e s t h e h yd r a u l i c f l u i d b a c k i n t o
the low-pressure accumulator, and the pump/motor applies torque to
the driveshaft through the clutch. If quick acceleration is required, the
F - 3 5 0 ' s d i e s e l e n g i n e w o r k s w i t h t h e H L A s ys t e m
The hydraulic launch assist system in the F -350 Tonka functions as a
secondary source of energy during peak power demand. It consists of a
low-pressure accumulator in blue, and a high -pressure accumulator in
red. The system captures energy normally dissipated as heat during
breaking, stores it, and uses it later during periods of peak power
demand.


Eighty percent of the initial kinetic energy is returned to the vehicle.
" T h e s ys t e m s t o r e s a p p r o x i m a t e l y 3 8 0 k J o f e n e r g y, " s a ys B r a d
Bohlmann, a mechanical engineer and business development
coordinator in Advanced Technology at Eaton's Fluid Power Group.
" W i t h t h a t m u c h e n e r g y, w e c a n a c c e l e r a t e a 1 0 , 0 0 0 - l b v e h i c l e f r o m a
dead stop to between 25 and 30 miles per hour with no assistance from
the vehicle's combustion engine."

" F o r d t h i n k s t h a t b o t h e l e c t r i c a n d h y d r a u l i c r e g e n e r a t i v e s ys t e m s h a v e
a f u t u r e , " s a ys J o h n B r e v i c k , a F o r d m e c h a n i c a l e n g i n e e r w o r k i n g o n
t h e H L A s ys t e m . " B u t f o r h e a v y v e h i c l e s l i k e o u r 1 0 , 0 0 0 - l b F - 3 5 0
t r u c k s , h yd r a u l i c s a r e b e t t e r a t c a p t u r i n g l o s t e n e r g y t h a n e l e c t r i c
s ys t e m s . "

E a t o n ' s B o h l m a n n e x p l a i n s t h a t t h e r e a l a d v a n t a g e o f h yd r a u l i c s i s i n
i t s p o w e r d e n s i t y. " H yd r a u l i c s i s c a p a b l e o f t r a n s f e r r i n g e n e r g y v e r y
q u i c k l y, " s a ys B o h l m a n n . " T h e r a t e o f e n e r g y t r a n s f e r i s i n a h yb r i d
e l e c t r i c s ys t e m o f a s i m i l a r s i z e i s m u c h l o w e r . "

B o h l m a n n a d d s t h a t t h e s p e c i f i c v o c a t i o n o r d r i v i n g c yc l e o f t h e
v e h i c l e d e t e r m i n e s w h e t h e r a h yb r i d h y d r a u l i c o r h yb r i d e l e c t r i c
s ys t e m i s b e s t s u i t e d f o r t h e v e h i c l e . " T h i n k o f h yd r a u l i c s a s a
s p r i n t e r , p r o v i d i n g f a s t b u r s t s o f p o w e r , " h e s a ys . " A n e l e c t r i c h yb r i d
is more like a marathon runner."
" T h e c h a l l e n g e n o w i s t o m a k e u s e o f t h e r e g e n e r a t i v e b r a k i n g s ys t e m
s e a m l e s s t o t h e c u s t o m e r , " s a ys F o r d ' s B r e v i c k . " W e s t i l l h a v e r o o m
for improvements and feel the HLA system has a lot of potential."

As for the future, Ford, Eaton, and the U.S. Environmental Protection
A g e n c y ( E P A ) a r e j o i n t l y c o n d u c t i n g r e s e a r c h o n h yd r a u l i c h yb r i d
vehicles, including internal combustion engines that would produce
h yd r a u l i c p r e s s u r e t o d r i v e t h e v e h i c l e . E a t o n s i g n e d b o t h a t e c h n o l o g y
license agreement and a cooperative research and development
agreement with the EPA for the development of future generation
s ys t e m s .

Inertia, Force and Mass
E v e r yt h i n g h a s i n e r t i a ; i f i t h a s a m a s s , i t h a s i n e r t i a . A h y b r i d
r e c l a i m s e n e r g y t h r o u g h t h e f u n d a m e n t a l s o f p h ys i c s . D o y o u r e m e m b e r
a n y h i g h s c h o o l o r c o l l e g e p h ys i c s ?

You apply a force to move an object. The equation for this is:

                                          F=ma
                       “F” being the force, “m” being the mass and
                                “a” being the acceleration

T h e f a s t e r yo u w a n t a n o b j e c t t o a c c e l e r a t e , t h e m o r e f o r c e yo u h a v e t o
a p p l y.

Let’s just look at the electric motor for now. Energy from the battery
(Watts) is applied to the coil windings in the motor. These windings
then produce a magnetic force on the rotor of the motor, which
produces torque on the output shaft. This torque is then applied to the
wheels of the car via a coupling of gears and shafts. When the wheel
turns, it applies a force to the ground, which due to friction between
the wheel and the ground causes the vehicle to move along the surface.
T h i s i s l i k e i f yo u w e r e i n a b o a t a t a d o c k , a n d yo u g r a b b e d t h e d o c k
a n d p u s h e d w i t h yo u r a r m . T h e f o r c e y o u a r e g e n e r a t i n g i s m o v i n g t h e
b o a t r e l a t i v e t o t h e l o c a t i o n o f t h e d o c k . T h e m o r e f o r c e y o u a p p l y, t h e
f a s t yo u g e t t h e b o a t t o m o v e .

Friction in Hybrids
T h e r e i s f r i c t i o n e v e r yw h e r e i n t h e h y b r i d s ys t e m . T h e r e i s e l e c t r i c a l
friction between the atoms and electr ons moving in the wires between
the battery and the motor and through the motor itself. There is
magnetic friction in the metal laminations that make up the magnetic
circuit of the motor, as well as in the magnets again on the atomic
level. Then, there is mechanical friction between every moving part,
such as the bearings, seals, gears, chains and so on. The by -product of
f r i c t i o n i s h e a t . T a k e yo u r h a n d s r u b t h e m t o g e t h e r   and your palms get
warm. The faster you do it, the faster they heat up.                                   Also, the har der
they are pressed together, the faster they will heat.                                  Friction is energy
lost to heat. When all of these losses are added up,                                   that is what
determines the efficiency of the vehicle.

Frictional Losses in Conventional Cars
A standard car generates torque to move the wheels to drive the vehicle
down the road. During this time, it is generating friction and losses.
W h e n yo u a p p l y s t a n d a r d b r a k e s , i t i s j u s t a n o t h e r f r i c t i o n d e v i c e t h a t
has specially designed material to handle the heat from friction, which
is applied to the drums and rotors that stop the wheel from turning.
The friction between the wheel and the ground stops the vehicle. This
standard vehicle has frictional losses to move the vehicle —and uses
the fundamental behind frictional losses to stop t he vehicle. So it’s a
lose-lose situation.

Transferring Torque Back to the Motor
T h i s i n e r t i a i s t h e f u n d a m e n t a l p r o p e r t y o f p h ys i c s t h a t i s u s e d t o
reclaim energy from the vehicle. Instead of using 100% of the
foundation brakes of the vehicle, which are the friction brakes, we now
let the linkages back to the motor such as the drive shafts, chains, and
gears transfer the torque from the wheels back into the motor shaft.
One of the unique things about most electric motors is that electrical
energy can be transferred into mechanical energy and also mechanical
e n e r g y c a n b e t r a n s f e r r e d b a c k i n t o e l e c t r i c a l e n e r g y. I n b o t h c a s e s ,
t h i s c a n b e d o n e v e r y e f f i c i e n t l y.

Thus, through the technology of the motor and motor controller, the
force at the wheels becomes t orque on the electric motor shaft. The
magnets on the shaft of the motor (called the rotor —the moving part of
the motor) move past the electric coils on the stator (the stationary
part of the motor) passing the magnetic fields of the magnets through
t h e c o i l s p r o d u c i n g e l e c t r i c i t y. T h i s e l e c t r i c i t y b e c o m e s e l e c t r i c a l
e n e r g y, w h i c h i s p u m p e d b a c k t o t h e b a t t e r y. T h i s , i n t u r n , c h a r g e s t h e
h yb r i d b a t t e r y p a c k . T h i s i s w h e r e t h e c o m m e n t “ r e g e n e r a t i o n ” o r
“reclaiming energy” comes from.

That is the basics of ho w regeneration works. How much energy you
can reclaim depends on a lot of factors. There are different
regeneration theories and designs, which fall into two groups: one
being called parallel regen and the other called series regen, which are
d i f f e r e n t f r o m t h e p a r a l l e l a n d s e r i e s h yb r i d s . T h e s e r e g e n g r o u p s
s t r i c t l y a r e d e s i g n t o p o l o g i e s f o r b r a k i n g s ys t e m s . I t a l s o m a t t e r s h o w
m a n y w h e e l s yo u a r e u s i n g t o r e c l a i m e n e r g y. M o s t v e h i c l e s t o d a t e a r e
f r o n t w h e e l d r i v e s o yo u c a n o n l y r e c l a i m e n e r g y f r o m t h e f r o n t
wheels. The back wheels still waste energy to standard friction brakes
unless they are somehow connected back to the electric motor. The
other factor is battery state of charge and how hard can you drive that
e n e r g y b a c k i n t o t h e b a t t e r y.
C H A PT E R 7 : CONCLUSION


T h e o r e t i c a l i n v e s t i g a t i o n s o f a r e g e n e r a t i v e b r a k i n g s ys t e m s h o w a b o u t
25% saving in fuel consumption.
       The lower operating and environment costs of a vehicle with
r e g e n e r a t i v e b r a k i n g s ys t e m s h o u l d m a k e i t m o r e a t t r a c t i v e t h a n a
conventional            one.         The      traditional          cost      of    the      s ys t e m    could       be
r e c o v e r e d i n t h e f e w ye a r s o n l y.
The exhaust emission of vehicle using the regenerative braking concept
would be much less than equivalent conventional vehicles as less fuel
are used for consumption.
T h e s e s ys t e m s a r e p a r t i c u l a r l y s u i t a b l e i n d e v e l o p i n g c o u n t r i e s s u c h a s
India where buses are the preferred means of transportation within the
cities.
BIBLIOGRAPHY


  1) General Motors Website (www.gm.com).
  2) www.sae.org
  3) www.google.com

				
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