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

1. 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.

2. 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.

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.

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

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

6. S. Mirzaei, S.M. Saghaiannejad, V. Tahani and M. Moallem, ‘Electromagnetic shock absorber’, Department of Electrical and Computer Engineering, IEEE 2001.

7. Bart L. J. Gysen, Jeroen L. G. Janssen, Johannes J. H. Paulides, Elena A. Lomonova, ‘Design aspects of an active electromagnetic suspension system for automotive applications’, IEEE transactions on industry applications, vol. 45, no. 5, September/October 2009.

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10. Shakeel Avadhany, Zack Anderson, U S patent 260935,’ Regenerative shock absorber.