POWER GENERATING SHOCK ABSORBER

A SEMINAR REPORT

Submitted in partial fulfilment for the award of the degree

Of

BACHELOR OF TECHNOLOGY

IN

MECHANICAL ENGINEERING
 Sr. No. Contents Pg. No.

1. CHAPTER1- INTRODUCTION……………………………………1

2. CHAPTER2-CONVENTIONAL SHOCK ABSORBER…………. 5

2.1 Conventional Shock Absorber
2.2 Working of Conventional Shock Absorber
2.3 Application of Conventional Shock Absorber

3. CHAPTER3-ELECTRIC SHOCK ABSORBER…………………. 8

3.1 Working of Electric Shock Absorber
3.2 Adjustable Dampening
3.3 Manufacturing Considerations

4. CHAPTER4-PERFORMANCE OF PGSA……………………….. 11

5. CHAPTER5-APPLICATION OF PGSA…………………………12

6. CHAPTER6-COST FACTOR…………………………………….13

7. CHAPTER7-FUTURE OF TECHNOLOGY……………………14

8. CHAPTER8-CONCLUSION……………………………………..15

REFERENCES
 List of Figures

Figure Contents Page

2.1 Conventional shock Absorber…………………………5

2.2 Working of Shock Absorbers………………………...6
2.3 Application of conventional shock Absorber………….7
3.1 Power Generating Shock Absorber……………………8
 POWER GENERATING SHOCK ABSORBER

ABSTRACT

An electromagnetic linear generator and regenerative electromagnetic shock

absorber is disclosed which converts variable frequency, repetitive intermittent
linear displacement motion to useful electrical power. The innovative device
provides for superposition of radial components of the magnetic flux density within
a coil winding array. Due to the vector superposition of the magnetic field and
magnetic flux from a plurality of magnets, a nearly four-fold increase in magnetic
flux density is achieved over conventional electromagnetic generator designs with
a potential sixteen-fold increase in power generating capacity. As a regenerative
shock absorber, the disclose device is capable of converting parasitic displacement
motion and vibration encountered under normal urban driving condition to a useful
electrical energy for powering vehicles and accessories or charging batteries in
electric and fossil fuel powered vehicles. The disclosed device is capable of high
power generation capacity and energy conversion efficiency with minimal weight
penalty for improved fuel efficiency.

KEYWORDS: shock absorber,displacement,magnetic field,vibration

 CHAPTER 1

1. INTRODUCTION

In the past decade, regenerative braking systems have become increasingly popular,
recovering energy that would otherwise be lost through braking. However, another
energy recovery mechanism that is still in the research stages is regenerative
suspension systems. This technology has the ability to continuously recover a
vehicle's vibrationless energy dissipation that occurs due to road irregularities,
vehicle acceleration, and braking, and use the energy to reduce fuel consumption.
Consumption; however, only 10%–16% fuel energy in the vehicles is utilized for
driving to overcome resistance from road friction and air drag . In addition to
thermal efficiency and braking energy, one important loss is kinetic energy
dissipated by shock absorbers. The function of vehicle suspension system is to
support the weight of vehicle body, to isolate the vehicle chassis from road
disturbances, and to enable the wheels to hold the road surface. Two chief elements
in suspension are spring and damper. Conventionally, damper is designed to
dissipate vibration energy into heat to attenuate the vibration which is transmitted
from road excitation. However, the dissipated heat is from fuel or electrical power.
It is a pity that so much energy is wasted.

Green manufacturing, also called environmentally conscious manufacturing, is one

of the most popular topics nowadays. The future of green manufacturing technology
is foreseeable, especially on vehicle industry. Since the suspension is an important
source of energy dissipation, it is feasible to harvest its vibration energy and convert
into regenerative energy to improve the vehicle fuel efficiency. Therefore, so called
regenerative suspensions arise as the times require. Instead of dissipating the
vibration energy into heat wastes, the damper in regenerative suspension will
transform the kinetic energy into electricity or other potential energy and store it for
late use. The stored energy can be used to tune the damping force of the damper to
improve the suspension performance or to power vehicle electronics to increase
vehicle fuel efficiency.

Road vehicles can expend a significant amount of energy in undesirable vertical

motions that are induced by road bumps, and much of that is dissipated in
conventional shock absorbers as they dampen the vertical motions. A conventional
automotive shock absorber dampens suspension movement to produce a controlled
action that keeps the tire firmly on the road. This is done by converting the kinetic
energy into heat energy, which is then absorbed by the shock’s oil.

The Power-Generating Shock Absorber (PGSA) converts this kinetic energy into
electricity instead of heat through the use of a Linear Motion Electromagnetic
System (LMES). The LMES uses a dense permanent magnet stack embedded in the
main piston, a switchable series of stator coil windings, a rectifier, and an electronic
control system to manage the varying electrical output and dampening load. The
bottom shaft of the PGSA mounts to the moving suspension member and forces the
magnet stack to reciprocate within the annular array of stator windings, producing
alternating current electricity. That electricity is then converted into direct current
through a full-wave rectifier and stored in the vehicle’s batteries. The electricity
generated by each PGSA can then be combined with electricity from other power
generation systems (e.g. regenerative braking) and stored in the vehicle’s batteries.

The electric shock absorber is a device that converts the kinetic energy of an
oscillating object into electric energy. This kinetic energy is normally dumped in a
form of thermal energy in a conventional, mechanical shock absorber. However,
only 10–16% of the available fuel energy is used t o drive the vehicle, i .e. to
overcome the resistance from road friction and air drag. Besides engine cycle
efficiency, one important mechanism of energy loss in automobiles is the dissipation
of kinetic energy during vehicle vibration and motion.

Goldner did some preliminary studies on the energy recovery in vehicles by using
a simple regenerative shock absorber composed of a single magnet and coils. They
estimated the recoverable energy for a 2500lb vehicle with an average speed of 20
m/s (45 m/h) is about 20% - 70% of the power that is needed for such a vehicle to
travel on a typical highway at 45 mph. Goldner patent for an electromagnetic linear
generator and shock absorber design was able to recover energy at a significant
efficiency, however, its weight of 70 kg (154lbs) may not be appropriate for a
passenger vehicle.
Oly Paz conducted a study of different configurations of linear induction generators
for vehicle suspension. The author presented a design method for one configuration
of a magnet and conductor set -up, which was calculated to have a theoretical
efficiency of 46%: however, a prototype was not fabricated . Finite element analysis
on this design would suggest that the actual efficiency would be significantly less
than predicted as a result of its ineffective use of high magnetically permeable
materials for certain components.

Abhijeet Gupta designed electromagnetic shock absorbers provide means for

recovering the energy dissipated in shock absorbers. Two electromagnetic shock
absorbers for potential use in vehicles are fabricated and tested them in a small all-
terrain vehicle (125 kg). Their experiment indicated that the rotary configuration
regenerated power at a much higher efficiency (21%) than the linear configuration:
however, its bulky des ign makes it incompatible with a passenger car. To further
magnify the motion and increase efficiency, regenerative absorbers composed of
ball screw and rotational electric motors have been developed by a number of
researchers.

Lie Zuo design characterize and test a retro fit regenerative shock absorber which
can efficiently recover the vibration energy in a compact space. Rare-earth
permanent magnets and high permeable magnetic loops are used to configure a four-
phase linear generator with increased efficiency and reduced weight. The finite
element method is used to analyze t he magnetic field and guide the design
optimization .

Presented in this paper are some of the results of a study aimed at determining the
effectiveness of efficiently transforming that energy into electrical power by using
optimally designed regenerative shock absorbers. In turn, the electrical power can
be used to recharge batteries or other efficient energy storage devices (e.g.,
flywheels) rather than be dissipated. The results of the study are encouraging - they
suggest that a significant amount of the vertical motion energy can be recovered and
stored. This can also be plugged to power management device that can also manage
power from other sources, such as regenerative braking systems. Thermoelectric
devices in shock absorber converts waste heat into electricity, or conformal solar
panels, The power is then fed into the car's electrical system to reduce the amount
of load on the alternator.
 CHAPTER 2

2. CONVENTIONAL SHOCK ABSORBERS

In this section we will first give an overview about the conventional types of shock
absorbers, working of conventional shock absorbers and their applications

2.1 Conventional Shock Absorbers

A Conventional Shock Absorber is a mechanical device designed to smooth out or

damp shock impulse, and dissipate kinetic energy. You would be think that as shock
absorbers dissipate energy then where that energy goes...?

 In most dashpots, energy is converted to heat inside the viscous fluid. In hydraulic
cylinders, the hydraulic fluid heats up
 In air cylinders, the hot air is usually exhausted to the atmosphere.
 In electromagnetic types dashpots, the dissipated energy can be stored and used
later.
 The amount of resistance a shock absorber develops depends on the speed of the
suspension and the number and size of the holes of the piston. All modern shock
absorbers are velocity sensitive hydraulic damping devices. This means that the
faster the suspension moves the more resistance the shock absorber provides.
Because of this feature, shock absorbers adjust themselves to road conditions.
 As a result, shock absorbers reduce the rate of:

o Bounce, Roll or sway

o Brake dive and acceleration squat

2.2 Working of Shock Absorbers

A conventional automotive shock absorber dampens suspension movement to

produce a controlled action that keeps the tire firmly on the road. Shocks absorbers
are used to damp oscillations by absorbing the energy contained in the springs or
torsion bars when the wheels of an automobile move up and down. Conventional
shock absorbers do not support vehicle weight. They reduce the dynamic wheel-
load variations and prevent the wheels from lifting off the road surface except on
extremely rough surfaces and making possible much more precise steering and
braking. The shock absorbers turn the kinetic energy of suspension motion into
thermal energy, or heat energy, to be dissipated through the hydraulic fluid.
 2.3 Applications of Shock Absorbers

 Shock absorbers are an important part of automobile and motorcycle suspensions,

aircraft landing gear, and the supports for many industrial machines.
 Large shock absorbers have also been used in structural engineering to reduce the
susceptibility of structures to earthquake damage and resonance.
 In rail cars and rapid transit systems because they prevent railcars from damaging
station platforms.
 CHAPTER 3

3. POWER GENERATING SHOCK ABSORBERS

Electric shock absorber is also known as Power-Generating Shock Absorber

(PGSA). The Power-Generating Shock Absorber (PGSA) converts this kinetic
energy into electricity instead of heat through the use of a Linear Motion
Electromagnetic System (LMES).

3.1 Working of Power Generating Shock Absorbers

The Power-Generating Shock Absorber (PGSA) converts this kinetic energy into
electricity instead of heat waste through the use of a Linear Motion Electromagnetic
System (LMES). The LMES uses a dense permanent magnet stack embedded in the
main piston, a switchable series of stator coil windings, a rectifier, and an electronic
control system to manage the varying electrical output and dampening load.

The bottom shaft of the PGSA mounts to the moving suspension member and forces
the magnet stack to reciprocate within the annular array of stator windings,
producing alternating current electricity. That electricity is then converted into
direct current through a full-wave rectifier and stored in the vehicle’s batteries. The
PGSA is the same basic size and shape, and mounts in the same way, as a standard
shock absorber or strut cartridge

3.2 Adjustable Dampening

An electronic control system monitors the requirements of each individual road

wheel’s suspension and varies the dampening by quickly switching on or off
individual stator coil rings. With all stator coil rings switched on the PGSA produces
a strong dampening force which can then be varied for disparate road conditions by
switching coils on and off as needed. This provides an added level of benefits in
allowing the shock to be very soft in cruising situations (small, high-frequency
movements) and instantly change to a sport shock in aggressive cornering situations
(longer, lower-frequency movements). Further, the rebound and compression
strokes can have different dampening values and application curves depending on
performance requirements.

This application could conceivably produce over twenty watts per wheel in normal
operation. City driving, with its varying road surface characteristics, as well as stop
and go traffic’s font-to-back loading, will generate more power than driving on
smooth roads at consistent speeds.

.
3.3 Manufacturing Considerations

Manufacture of the Power-Generating Shock Absorber will require a machined

main shaft with embedded permanent magnet stack, a strong air-gap cylinder
housing, high quality stator windings, and robust slide bearings. The magnet
assembly consists of an inner magnet stack surrounded concentrically by a larger
diameter outer magnet stack. Each stack consists of three axially magnetized ring
magnets separated by two iron-pole rings and two additional pole rings located at
the ends of the stack. Other systems, such as microprocessor-controlled voltage,
current, and dampening regulation, external casing, protective bellows, etc. will also
need to be designed and tested. The magnetic finite element method is then used for
the design optimization to increase the power density, and finally a refined model
of the energy harvesting is presented
 CHAPTER 4

4. PERFORMANCE OF PGSA
 A prototype of a shock absorber for vehicles which can harness and generate
electricity back into the vehicle is made by the team of researchers. The team claims that
their prototype increases a vehicle's fuel-efficiency by up to 10 percent by using a
"hydraulic system that forces fluid through a turbine attached to a generator."

 The system performs best on heavy, off-road vehicles moving quickly over rough
terrain.

 Currently, only 10-16% of a vehicle’s fuel energy is used to drive the vehicle, i.e.
to overcome the resistance from road friction and air drag. The rest is lost due to braking,
vibrational energy dissipation, and other forms of loss.

 Prof. Lie Zuo estimated that for a middle-size vehicle, 100W, 400W, and 1600W
of average power is available for harvesting from the regenerative shock absorbers while
driving on Class B (good), C (average), and D (poor) highways at 60 mph, which is
comparable with car alternators (500-600W). And the energy potential for trucks, rail
cars, and off-road vehicles is on the order of 1kW-10kW.

 This represents a potential of 2-3% fuel efficiency increase in conventional cars,

up to 6% in military vehicles and up to 8% for hybrid vehicles.

 ”The power regeneration is proportional to the square of the magnetic flux across
the coils,” Lie Zuo said.
 CHAPTER 5

5. APPLICATIONS OF PGSA
 This technology can be applied to any type of vehicle that employs movable suspension
technology and uses electricity in some form as its fuel.

 It is successfully tested on electric vehicles. The system performs best on heavy, off-road
vehicles moving quickly over rough terrain, so the company is targeting military
applications.

 It also is sensible that having onboard power generation could be a real advantage in
military situations where troops are moving in remote areas without readily available
fuel sources. Conserving fuel in those scenarios, especially during combat, could be the
difference between life and death.

 What comes to mind quickly for non-military applications Is the commercial trucking
industry. While they typically run trucks over roadways, their payloads of tens of
thousands of pounds couple even with small, constant movements might generate a fair
amount of electricity with shock absorber generators.

 To improve vehicle handling, the power controller uses information from

accelerometers and other sensors to change the resistance from the generators, which
stiffens or softens the suspension.

 For example, if the sensors detect the car starting a turn, the power controller can
increase the resistance from the shock absorbers on the outer wheels, improving
cornering,

 The shock absorbers are connected to a power management system that can interface
with other sources of power, such as regenerative braking systems, thermoelectric
devices that can convert waste heat into electricity.
 CHAPTER 6

6. COST FACTOR
 The most important factor that comes in our mind is COST. What is the use of new
system if it costs more? The new system should be relatively low cost then only it can
serve the purpose.

 The companies has emphasized using off-the-shelf parts, where possible, to keep down
costs. Diamond (Owner of Levant Power) notes that active shock absorbers have failed
commercially in the past because they were too expensive.

 What distinguishes the new system is, its relatively low cost and ability to generate
electricity.

 In order to reduce costs as much as possible, the shock absorbers are built using mostly
components already available on the market. They want, therefore, to avoid repeating
the failure experienced time ago by the active suspensions, which were practically
discarded because of their costs too high for conventional vehicles.

 The shock absorbers and control electronics will cost slightly more than conventional
shock absorbers, but the recoup time for cost of installation in trucks and services
vehicles is 1-2 years, and 3-4 years for typical passenger vehicles. And that is for existing
vehicles. Hopefully in the near future they will be in all new cars too.
 CHAPTER 7

7. FUTURE OF THIS TECHNOLOGY

 In the future, the researchers are planning to increase the energy density and
efficiency of the system by further increasing the magnetic field intensity and improving
the harvesting electrical circuit.

 Wireless sensors and actuators will be used in future. For example, if the sensors detect
the car starting a turn, the power controller can increase the resistance from the shock
absorbers on the outer wheels, improving cornering.

 There is still room for improvement in the overall design of the regenerative system, and
researchers are working on such improvement.

 Stony Brook University, Tufts University and General motors are developing systems of
their own that use no fluids, only electromagnetic resistance. They says one of the
biggest challenges in designing such systems is making them small enough to fit into
existing vehicles, yet ensuring they are still capable of converting a useful amount of
electricity.

 There is some discussion taking place about the potential of adding their technology to
the Humvee’s replacement, the Joint Light Tactical Vehicle and military vehicles.
 CHAPTER 8

8. CONCLUSION
 A larger magnetic field will be necessary if more power needs to be generated.

 Conversion of energy produced by a vehicle shock absorbers movements into electrical

energy, allows a significant fuel savings.

 It is possible to obtain a fuel saving between 1.5 and 6%, depending on the vehicle and
on the driving conditions. Moreover, the researchers say that this system can improve
the stability of the vehicle.

 Regenerative braking harvests large amount of power in a very short time, in an

intermittent manner,‖ Lie Zuo said. ―However, the regenerative shock absorbers can
harvest the power in a continuous way. On the smooth highway road, The electric shock
absorbers can improve the fuel efficiency by 2%, and on bumpy roads up to 10% increase
can be expected.

 More researchers are going on to extend the tests involving other types of vehicles such
as trucks, buses and other automotive vehicles.
 REFERENCES
 Lei Zuo, Brian Scully, Jurgen Shestani and Yu Zhou, ‘Design and characterization of an
electromagnetic energy harvester for vehicle suspensions’, Journal of Smart Materials
and Structures, Volume 19, Number 4.

 Gupta A, Jendrzejczyk J A, Mulcahy T M and Hull J R , ‘Design of electromagnetic shock

absorbers’, International Journal of Mechanics & Material Design, Volume 3, Number 3.

 Goldner R B, Zerigian P and Hull J R, ‘A preliminary study of energy recovery in vehicles

by using regenerative magnetic shock absorbers’, SAE Paper #2001-01-2071.

 Pei-Sheng Zhang and Lei Zuo, ’Energy harvesting, ride comfort, and road handling
of regenerative vehicle suspensions’, ASME Journal of Vibration and Acoustics, 2012.

 Zhen Longxin and Wei Xiaogang , ‘Structure and Performance Analysis of Regenerative
Electromagnetic Shock Absorber’, Journal of networks, vol. 5, no. 12, December 2010