ELECTROMAGNETIC
REGENERATIVE SHOCK
ABSORBER
Submitted by:
Sanjeev Bijarnia
09106EN061
B.Tech Part-IV
Mechanical Engg.
CONTENTS
1. Introduction
2. Amount Of Energy Available For Recovery in a Vehicle Suspension
3. Alternative Ways to Harvest Energy in Vehicle Suspension
4. Comparison to Get Best Alternative-Electromagnetic System
5. Electromagnetic Regenerative Shock Absorber In Vehicle Suspensions
6. Electromagnetic Design Of Regenerative Shock Absorber
7. Primary Equation For Regenerated Voltage
8. Static Magnetic Analysis
9. Results Of Static Flux Analysis
10. Manufacturing Of Electromagnetic Regenerative Shock Absorbers
11. Testing Of Electromagnetic Regenerative Shock Absorber
12. Experimental Results
13. Features
14. Disadvantages
15. Conclusions
INTRODUCTION
If all the available vibration energy is recovered, it is possible to use regenerative
shock absorber to charge the battery of vehicle, instead of alternator. Thus
alternator load on vehicle engine can be decreased or removed completely.
Energy recovery from suspension system is necessary to reduces fuel
consumption. Eventually it will reduce pollution of air by lesser emission of
pollutant gases.
ENERGY HARVESTING POTENTIAL
Source:-1
AMOUNT OF ENERGY AVAILABLE FOR
RECOVERY IN A VEHICLE SUSPENSION
This energy in compressed spring can be given by
equation –
E= 𝑓𝑑𝑥 =1
2𝑘𝑥2
Let k= 1.2×10^5 N/m and supporting vehicle mass
approximately 1000 kg
amounts of energy in spring –
ALTERNATIVE WAYS TO HARVEST ENERGY
IN VEHICLE SUSPENSION
Piezoelectric:- Piezo electric material is used to generate the
voltage
Hydraulic:- pressurized oil is passed through small turbine form
pipes
Electromagnetic:- Electromagnetic system is based on Faraday’s Law of
electromagnetic induction
WHICH ONE IS BEST
Electromagnetic system is the best one
Why? No heat generation due to friction
Possible to implement in vehicle suspension with minimum design changes
Linear design of electromagnetic energy harvester system
Can harvest energy in both expansion and compression
ELECTROMAGNETIC REGENERATIVE SHOCK
ABSORBER IN VEHICLE SUSPENSIONS
Figure : Schematic View of
electromagnetic
shock absorber
Principle:- converts the kinetic energy of vehicle vibrations
into useful electrical power
Main Components:- 1. Ring shaped permanent
magnets
2. Ring-shaped spacers (highly
magnetic permeability)
3. Center rod for stacking of
magnets and spacers
ELECTROMAGNETIC DESIGN OF
REGENERATIVE SHOCK ABSORBER
Fig. ¼ Cut section of the linear energy harvester & its
equivalent magnetic circuit
PRIMARY EQUATION FOR REGENERATED
VOLTAGE
Faradays law of electromagnetic
induction:- When an electric conductor is moved through a magnetic
field, a potential difference is induced between the ends of the conductor
according to above law- V = n B v L
PHASE VARIATION
Figure 3: Diagram of the four-phase generator
configuration: the coils move in the magnetic field during
the vibration of vehicle suspensions.
STATIC MAGNETIC ANALYSIS
If the materials of center rod and outer tube are
varied, following three possible combinations of
harvester can be analyzed –
1. M. S. center rod and no outer cylinder (nonmagnetic
outer part)
2. Stainless steel center rod & no outer cylinder
(nonmagnetic outer part)
3. Stainless steel center rod with M S outer cylinder.
(a) (b) (c)
Fig. 2D Electromagnetic flux analysis of harvester-
(a) MS center rod & no outer cylinder,
(b) SS center rod with no outer cylinder
(c) SS Center Rod And M S Outer Tube
Figure 6: Magnetic flux through the middle of the coils in the radial direction obtained by
using finite element analysis. The energy density of the harvester in the improved design
will be more than doubled.
MANUFACTURING OF ELECTROMAGNETIC
REGENERATIVE SHOCK ABSORBER
Fig : Exploded view of assembly of components
The permanent magnets NdFeB (grade N32) (High Magnetic
Density)
Copper wire of 27 AWG (superior conductivity and low resistivity)
TESTING OF ELECTROMAGNETIC
REGENERATIVE SHOCK ABSORBER
EXPERIMENTAL RESULTS
Figure 11: The recorded waveforms of
regenerated voltages under 10 Hz excitation:
0. phase with 0.36H amplitude/0.6 V
excitation (thicker solid), 90. phase with
0.36H amplitude (thicker dashed), 0. phase
with 0.1H amplitude/0.2 V excitation (solid)
and 90. Phase with 0.1H amplitude (dashed).
H = 11.35 mm.
Figure 12: RMS voltage output versus
input frequency for 0◦ phase coil set
(eight coils) at different shaker excitation
voltages.
FEATURES
The system draws about two horsepower or one-third the load of a typical air conditioner. While it can exert 50 kilowatts (67 horsepower) of energy to leap a 2x6(plank) covers 49 kilowatts cushioning the landing, with the shocks working like generators.
Torsion bars and shock units weigh about what two conventional springs and shocks. The controllers and upsized alternator also add some weight, but the total should be less than that of a hydraulic active suspension.
To save power the system is regenerative. When the far side of a pothole helps to push the wheel up almost all the power is recovered. The motors momentarily become generators, shunting the recovered energy to storage, either in the engine battery or in some other device. The system ends up consuming one-third of the energy used by a cars air-conditioner.
ECONOMIC BENEFITS Assume 75% harvesting efficiency, X 400W=300 Watts electricity
harvested.
What it means to us?
-Typical vehicle use 250-350 watts electricity which is powered
by the alternator:300 watts electricity= 1800 watts fuel power
-Average fossil fuel use energy 80kwh per 100km and prototype
electric and hybrid car use less than 20kwh per 100km
2-10% fuel efficiency increase for conventional and electric/hybrid
vehicles
DISADVANTAGES
The main drawback of the system is the cost. As it uses neodymium magnets which are costly to manufacture. Thus this makes this suspension system costlier than any other suspension available. Thus this system can be seen in only high end cars
The second drawback is ,when this system breakdowns it’s very difficult and costly affair to repair it .The other system available can be easily be repaired
The system is very complex and requires high precision machinery and skilled workers to manufacture
CONCLUSIONS
The results of experiment carried out for the variation in regenerated voltage against in excitation frequency & amplitude shows that for input frequency 6 Hz and amplitude 20 mm, cyclic RMS voltage generated for 8 coil set of 0º phase and 8 coil set of 90º phase is 5.5 & 5.0 volts respectively. The full scale single regenerative shock absorber was able to harvest 8 W of energy at 0.25–0.5 m s-1 RMS suspension velocity. It was also found that the frequency of the regenerated voltage does not necessarily have the same frequency as the excitation. Instead, the wave shapes of the regenerated voltage will depend on excitation frequency, amplitude and equilibrium position. The overall conclusion of this research work is that it is possible to harvest energy from vehicle vibrations travelling on a bumpy road.
REFERENCES
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