2. Outline
Why we need brakes?
Overview
Topics related to braking
Regenerative Braking
Working and Elements
Types of KERBS
Storage of Energy
Advantages and Limitations
Conclusion
References
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3. Why we need brakes ?
We need brakes to reduce the speed of moving objects
or stop them.
Formula 1 cars are
capable of
decelerating from
124-mph to a
standstill in only 2.9
seconds.
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4. Over view
Brakes translate a push of a
pedal to slowing down your car.
Disc or Drum brakes play the
part of the brake system that
does the actual work of
stopping the car.
Friction between the various
mating surfaces results in
braking action and slow down
of car.
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5. Topics related to braking
Pascal’s law
“Pressure exerted anywhere in a confined incompressible
fluid is transmitted equally in all directions throughout
the fluid such that the pressure ratio (initial difference)
remains the same”
Hydraulic Press – basic concept for brakes
Braking action
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7. Types of Brakes
Basically, purpose of brakes is to apply mechanical
resistance i.e. Friction on rotating wheels in order to
slow down the car.
The various methods used to apply friction are :
Hydraulic Braking System
Electromagnetic System
Pumping brakes
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8. Regenerative braking
• Is an energy recovery mechanism which slows a
vehicle or object down by converting its kinetic
energy into another form, which can be either
used immediately or stored until needed
• The energy can be stored :
• electrically by battery or capacitors bank
• mechanically via pneumatics, hydraulics
• kinetic energy in rotating flywheels
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9. Energy transformation
Friction Brake: Regenerative Brake:
This brake system converts Capturing kinetic energy
the kinetic energy of vehicle generated from braking and
motion into heat converting it to
electricity, hydraulic pressure
or spring force.
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11. Working of KERBS
• Vehicle has forward momentum
• Auxiliary systems, like Hydraulic cylinders, Flywheel
apparatus, etc. are coupled to wheels
• When brakes are applied, the friction between braking
elements and wheel, engages the regenerative system
• The rotors experience opposing torque, this activates the
system :
• Hydraulic pump used to pressurize fluid and store in
cylinders
• Flywheel used to store as rotary motion
• Motor/ Generator used to generate electricity and store in
batteries
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12. Types of KERBS
Hydraulic
Hydrostatic Regenerative Braking (HRB) system uses
electrical/electronic Components as well as hydraulics to
improve vehicle fuel economy
Flywheel assisted
Engines have been using energy-storing devices called
flywheels, which are rotating disc, which are considered as
“energy storing reservoirs”
Nitilon Springs assisted
Special purpose Compression springs are used to store
energy as spring force
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13. Hydraulic KERBS
Braking energy is
converted to hydraulic
pressure and stored in a
high-pressure hydraulic
accumulator
When the vehicle
accelerates, the stored
hydraulic energy is applied
to the transmission, hence
reducing the fuel to be
combusted in the engine
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14. Flywheel KERBS
Packaged inside a single
housing is a shaft
mounted flywheel that is
connected via a
chain/gear to the drive
shaft
During braking and
coasting, the flywheel
spools-up (accelerates as
it spins) and absorbs a
storehouse of otherwise
wasted energy
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15. Storage of Kinetic Energy
• In a Hydraulic KERBS,
• stored as fluid pressure in hydarulic cylinder.
• In Flywheel assisted KERBS,
• stored as rotational energy in flywheel.
• In Nitilon spring assisted KERBS,
• stored as spring force or potential energy.
• Recent development is that a Motor/Generator is
used to convert kinetic energy to electrical energy.
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16. Regenerative Braking Controllers
• The brake controller makes the entire regenerative
braking process possible.
• its monitors the speed of the wheels
• calculate how much torque -- rotational force -- is
available to be fed back
• deciding whether the stored energy should be released
immediately or stored temporarily
• Special ECU used for the controlling purpose
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17. Comparison
Hydraulic KERBS Flywheel KERBS
5.55 Wh/kg at 250 Bar Maximum power
pressure boost of 60 kW for
Energy efficiency at 6.67 seconds
73% Compact weight and
Heavy equipments size
Limited power storage Higher efficiency
Leakage of hydraulic Lower cost
fluid Can be used for small
vehicles also
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19. Advantage of regenerative breaking
• Improves fuel efficiency
• Conservation of Energy
• Wear reduction
• Higher pick up response
• Lower emissions
• Kinetic energy regenerated can be stored in form
of electricity in batteries, which can be used to
power up other auxiliary systems
• Use of KERBS in hybrid and electric vehicles will
increase the travel distance
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20. - For example:
The Delhi Metro saved around 90,000 tons of carbon
dioxide (CO2) from being released into the
atmosphere by regenerating 112,500 megawatt hours of
electricity through the use of regenerative braking
systems between 2004 and 2007.
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21. Limitations of regenerative breaking
Added weight of minimum of 25 kilos
The regenerative braking effect drops off at lower speeds
The friction brake is a necessary back-up in the event of
failure of the regenerative brake.
The amount of electrical energy capable of dissipation is
limited by the capacity of the supply system
Under emergency braking it is desirable that the braking
force exerted be the maximum
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22. New braking system technologies
Anti-Lock Brake System (ABS)
Traction Control System (TCS)
Electronic Stability Program (ESP)
Regenerative braking system
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23. Conclusion
Increased fuel efficiency
The lower operating and environment costs
All vehicles in motion can benefit from utilizing
regeneration to recapture energy that would otherwise
be lost.
As designers and engineers perfect regenerative
braking systems, they will become more and more
common
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24. References
Cibulka, J. Kinetic energy recovery system by means of
flywheel energy storage Advanced engineering
3(2009)1, ISSN 1846-5900
www.gm.com
www.howstuffworks.com
www.wikipedia.org
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