# Foo - Shocks as a generator?

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View Full Version : Shocks as a generator?

phantomcow2
08-16-07, 09:00 PM
So I know that by Faraday's law, a voltage is produced when there is a changing magnetic field in a coil of wire.
Well, what if one had shocks like for a car. Have a coil around the shocks, and then a magnetic fixed to the shocks. So when the shocks move, the magnet moves, but not hte coil. This would produce a voltage at the ends of the wire.

SO what if one did this to say....an electric car? Every time you went over a pothole, you'd be generating a voltage. You could charge your batteries as you move. If I am not mistaken, the output voltage according to the formula that quantifies Faraday's law is a function of flux density. So if one used a good magnet like a neodymium core from a step motor, I think I would be able to generate a decent amount of voltage.

Is this a glaringly bad idea? Am I missing something? Or could this work?

G-Whacker
08-16-07, 09:24 PM
Sound theory (novel concept), iffy real world value.

Will the generated voltage of pot holes/ bumps outweigh the cost of replacing all those worm shocks? If you drive normally, will the cost of generater shocks and the systems they're attached to be worth the hassle and cost of the installation/ maintenance thereof?

Braking is where the power is at.
(BTW- I'm just an RF guy- so what do I know?)

now you'll excuse me while I steal this idea!

ryder47
08-16-07, 09:58 PM
So I know that by Faraday's law, a voltage is produced when there is a changing magnetic field in a coil of wire.
Well, what if one had shocks like for a car. Have a coil around the shocks, and then a magnetic fixed to the shocks. So when the shocks move, the magnet moves, but not hte coil. This would produce a voltage at the ends of the wire.

SO what if one did this to say....an electric car? Every time you went over a pothole, you'd be generating a voltage. You could charge your batteries as you move. If I am not mistaken, the output voltage according to the formula that quantifies Faraday's law is a function of flux density. So if one used a good magnet like a neodymium core from a step motor, I think I would be able to generate a decent amount of voltage.

Is this a glaringly bad idea? Am I missing something? Or could this work?

I would believe giving the nature of our roads and average amount of travel in the shocks that the output would be hard to regulate as well as produce in suffiecent quantity to justify the development costs let alone the production issues. Here in South Florida potholes are fairly rare as compared to other areas of the country and potholes are not at all vehicle friendly. As G-Whacker pointed out the biggest bang for the buck is ReGen from the braking system as well as the drive motors as of such a vehicle as it comes to a stop. We've done a number of Regen drives for large electric motors for our customers who are getting paybacks from saved energy in as little as 1-2 years.

timmyquest
08-16-07, 10:13 PM
I would believe giving the nature of our roads and average amount of travel in the shocks that the output would be hard to regulate as well as produce in suffiecent quantity to justify the development costs let alone the production issues. Here in South Florida potholes are fairly rare as compared to other areas of the country and potholes are not at all vehicle friendly. As G-Whacker pointed out the biggest bang for the buck is ReGen from the braking system as well as the drive motors as of such a vehicle as it comes to a stop. We've done a number of Regen drives for large electric motors for our customers who are getting paybacks from saved energy in as little as 1-2 years.

Sure you couldn't run a car entirely on this...but what if it was just yet anther way to power a hybrid engine...i think it's pretty clever.

Hmmm

phantomcow2
08-16-07, 10:14 PM
I was thinking it could assist the range of an electric car.
Here in NH, we have PLENTY of pothole roads. With our winters, it would be great.

ryder47
08-16-07, 10:33 PM
Sure you couldn't run a car entirely on this...but what if it was just yet anther way to power a hybrid engine...i think it's pretty clever.

Hmmm

Clever, sure. Rates an A+. Practical however, I would think the amount of power acheived would be rather small compared to what Regen would return for less money considering that Regen technology already exists and is being used not only in industry but alternative vehicles in development. New ideas are great and need to be explored and tested for viability. Under that vein lets put wind turbines on top of our cars as well to harness the power of the wind as we cruise down the highway. Now there's an idea, but is it pratical?

phantomcow2
08-16-07, 10:49 PM
I'm not sure how much potential this could have. I don't know how to quantify the actual amount of current produced. I know voltage is a function of Flux density and area of coils. So coils in a large diameter with a strong permanent magnet would yield the best results. But high flux density permanent magnets are pretty expensive I think.
I suppose if you got a high enough voltage produced, you could get a transformer to give you a few more amps and a little less EMF. BUt given the weight of the transformer, it may not be effective. Unless you can get a sort of wh/kg ratio going that is better than a lead acid battery.

phantomcow2
08-16-07, 10:50 PM
Clever, sure. Rates an A+. Practical however, I would think the amount of power acheived would be rather small compared to what Regen would return for less money considering that Regen technology already exists and is being used not only in industry but alternative vehicles in development. New ideas are great and need to be explored and tested for viability. Under that vein lets put wind turbines on top of our cars as well to harness the power of the wind as we cruise down the highway. Now there's an idea, but is it pratical?

That's been thought of before though. I believe the conclusion was that this consumes more energy as drag than energy it produces.

ryder47
08-16-07, 10:54 PM
I was thinking it could assist the range of an electric car.
Here in NH, we have PLENTY of pothole roads. With our winters, it would be great.

You've asked us to play devils advocate and for me that's a game. I'm from up north as well, upstate NY and western Mass. and I'm no stranger to potholes. Personally I tried to avoid the darn things as they are pretty hard on the suspension, tires and rims not to mention the shock to the rest of parts that creaked, rattled and groaned when you couldn't avoid them. In the world of engineering nothing is for free and there is always a cost associated with the benefit. The test is whether the benefit outways the cost.

Let's ignore the issues with driving through potholes for the moment and the developement of this technology and assume you have a working prototype. In order to reach the maximum benefit we would now have to design roads with potholes on purpose to occur at a regular intervals. And given the variance of vehicle sizes the potholes will have to be the full width across the lanes to insure that all four tires engage the potholes. How deep will they be? Not to deep as the ground clearance on my daughters Jetta isn't all that great compared to my pickup. And how about the width from the front to the back of the pot hole as well, it should be enough to swallow the foot print of a tire as well as how far apart. The closer the better to insure maximum rate of movement in the shocks.

I think I've rambled on long enough, but to bring this new technology to the forefront these questions need to be answered.

phantomcow2
08-16-07, 11:02 PM
Well, I don't think I would want to rely on these to completely power a car! I don't think many people would be driving if that was the case :eek:
I was thinking of it being more of a supplemental thing. Avoid potholes because obviously they aren't good, but if you do go over one, at least you get some benefit. At least it takes advantage of the inability to maintain every road. It makes something generally regarded as bad have at least one benefit.

If I wanted to see a real radical change in how we power vehicles, I would say let's put very efficient solar panels on our cars and drive electrics with the Li-Ion batteries. This of course, is not at all cost effective right now.

iamlucky13
08-16-07, 11:09 PM
You know, it would seriously be a good EE or ME student project.

I doubt it could fully replace the dampers in a shock, but it would help. The damper is what typically wears out in a shock, so it wouldn't hurt to give it a hand in dissipating the energy.

Anyway, you don't really have to design potholes into the road. The energy generated from the bumps you're already bound to come across is just a bonus.

By the way, a 1000 kg vehicle moving through 10 cm of suspension travel gains around a kJ of potential energy. If it does this at 1/2 Hz consistently that's about 500 Watts (a little under a horsepower), but I seriously doubt you could come close to 100% efficiency, especially if you can't get enough damping from the Faraday effect to completely replace the oil dampers.

I've read somewhere before that a small sedan typically takes about 30 horsepower to maintain highway speeds, so you're looking at a maximum 3% energy payback. I don't really think my parameters (10 cm at a continuous 1/2 Hz, ~100% efficiency) are very realistic, though.

Krink
08-16-07, 11:24 PM
Don't think potholes on asphalt, think bumpy gravel roads, washboard, two track. The first application would be hybrid ranch trucks (driven with loads at low speed over bumpy terrain with relatively less braking) not cars (driven relatively light at high speed over smooth terrain and high demand braking).

lyeinyoureye
08-16-07, 11:45 PM

Krink
08-16-07, 11:55 PM

Isn't the Bose approach almost the opposite--using power to run the suspension, rather than use the suspension to provide power?

lyeinyoureye
08-16-07, 11:59 PM
I'm pretty sure it could work both ways, but don't quote me on it.

Krink
08-17-07, 12:13 AM
I'm pretty sure it could work both ways, but don't quote me on it.

I'm quoting you. ;)

Maybe some of the technology could overlap, so maybe some of the patents. More so if Bose used the movement of the shock to help power the (ridiculously) overkill suspension system. But, the Bose suspension apparently anticipates the conditions (leaps over a 2X6) rather than reacts to them as in a normal suspension. So energy is expended before the obstacle, rather than absorbing energy from the obstacle (as in standard suspension or Phantom's suggestion). I think it's opposite to the Phantom's idea, but the descriptions of the Bose are pretty sketchy, so you might be right.

Krink
08-17-07, 12:26 AM
Eventually, they concluded that their dream would be within reach if they could make some breakthroughs in electromagnetics, power amplifiers and control algorithms. They worked on those challenges and bet successfully that the computer industry would accelerate computational speed to help the suspension rapidly respond to changing road conditions..

Hmmm.....

lyeinyoureye
08-17-07, 12:37 AM
But, the Bose suspension apparently anticipates the conditions (leaps over a 2X6) rather than reacts to them as in a normal suspension. So energy is expended before the obstacle, rather than absorbing energy from the obstacle (as in standard suspension or Phantom's suggestion).
FRAMINGHAM, Massachusetts -- In a cleared-out parking lot at Bose's headquarters, a test driver guides a Lexus at 25 mph toward what would appear to be an unfriendly introduction to a two-by-six lying on its side, ankle-high.

A childlike grin spreads across 76-year-old Amar Bose's face as the vehicle does something most can't: jump over the board, like a cat bounding over a fallen log.

The sedan's experimental, Bose-designed suspension, driven by four electromagnetic motors, had quickly pulled each wheel up, then down. It's a stunt, triggered when the car passed over a reflective strip that activated a sensor linked to the suspension.

I think it's opposite to the Phantom's idea, but the descriptions of the Bose are pretty sketchy, so you might be right.*sigh* (http://www.bose.com/controller?event=VIEW_STATIC_PAGE_EVENT&url=/learning/project_sound/suspension_components.jsp&ck=0)
The regenerative power amplifiers allow power to flow into the linear electromagnetic motor and also allow power to be returned from the motor. For example, when the Bose suspension encounters a pothole, power is used to extend the motor and isolate the vehicle's occupants from the disturbance. On the far side of the pothole, the motor operates as a generator and returns power back through the amplifier. In so doing, the Bose suspension requires less than a third of the power of a typical vehicle's air conditioner system.

Not to discourage anyone from tinkering around, just that it's been done. :)

Krink
08-17-07, 12:50 AM
D'oh!

That said, looks pretty bright for Phantom's idea. Instead of spending the energy produced on running the elaborate suspension, you send the energy to the batteries to run the drive. Let people bounce around like they always have, save a glacier.

lyeinyoureye
08-17-07, 01:13 AM
Heh, you're not gonna get much energy out of trying to recapture what ever is spent overcoming imperfections in the road. Better aero, better tires, and more efficient engine operation are where it's at. This is just something for the luxury market, who really don't care much about energy consumption in the first place. It may eventually work it's way down to the lower cost versions of said platforms if it's adopted.

Krink
08-17-07, 01:32 AM
I agree. That's why I said the best application would not be in cars running light on smooth roads, but more likely in something like farm trucks running heavy on rough roads.

It could be a nice contrast to hybrids recharging on braking system. A truck running 30 miles to town on washboard gravel in Idaho may never brake, but has a lot of play in the suspension.

Tom Stormcrowe
08-17-07, 08:02 AM
It's interesting at least ,whether it's developable from a practical standpoint. It tells me a whole lot about your thinking process though, PC! If you ever go to work in an advanced technology development company, let me know so I can buy stock! ;)

jsharr
08-17-07, 09:14 AM
I had a vehicle in the 70s that used the suspension to provide it's forward motion:

http://i144.photobucket.com/albums/r162/jsharr/inchworm.jpg

Krink
08-17-07, 09:21 AM
I found this schematic of the Bose suspension.

phantomcow2
08-17-07, 12:01 PM
Well, I think the voltage produced is a function of how fast the magnetic field changes. So if you go over a bump slowly, you won't produce as much. And since your car has a large q factor, the shock is dampened very quickly. SO it would probably only complete one oscillation before it's been completely damped.
You would have to seriously compromise comfort and possible safety to generate something.
The voltage would never be the same, and I suspect would actually be an AC in this instance.

So it would be required to get a large in area and most importantly, high flux density permanent magnet. Damn :(, it's never easy.

DannoXYZ
08-17-07, 12:37 PM
Well, I think the voltage produced is a function of how fast the magnetic field changes. So if you go over a bump slowly, you won't produce as much. And since your car has a large q factor, the shock is dampened very quickly. SO it would probably only complete one oscillation before it's been completely damped.
You would have to seriously compromise comfort and possible safety to generate something.
The voltage would never be the same, and I suspect would actually be an AC in this instance.

So it would be required to get a large in area and most importantly, high flux density permanent magnet. Damn :(, it's never easy.Good idea though! What you can do to not compromise the suspension motion in order to extract power from suspension movements would be to replace mechanical shock damping with the opposing force from self-induced hysteresis of the coil. So if without the damper-generator working, the hydraulic shocks provides 100% of the damping, you can then back off the hydraulic damping to match the resistance of the coil. So on a big pothole, you can reduce the hydraulics to 50% and the coil generator would provide the other 50% of the damping. Then adjust this balance dynamically to match the types of bumps you encountre. The experience for the users would be a suspension that has the same feel regardless of whether the generator is in operation or not.

What you want to do is characterise the motion of the suspension on an existing car over existing roads. There are cheap accelerometers which functions as "motion microphones" to record the actual movement and speed of the suspension. Then datalog this movement and plug into the equations for mag-flux & induced currents to see actual amounts of power you'll be able to generate.

Another way to kind of approximate this power is to measure the temperature of the hydraulic shocks. Drive over the same road and measure before & after temperatures. Then calculate how much power is required to change that volume of metal and hydraulic-fluid to the measured delta-T.

Tappets
08-17-07, 01:24 PM
wrapping wire around socks with a magnet in them?

i don't see how that will work.

i guess that's why i could never be an engineer.

phantomcow2
08-17-07, 03:10 PM
wrapping wire around socks with a magnet in them?

i don't see how that will work.

i guess that's why i could never be an engineer.

When you have some magnetic field which is moving relative to the position of a coil of wire, electricity is produced. What I was thinking about works on the same principle as a rotary generator like you might have, or a power plant probably uses. Except my thoughts were to have a linear motion setup instead of rotary.

Tappets
08-17-07, 04:02 PM
wrapping wire around socks with a magnet in them?

i don't see how that will work.

actually, i was being silly with the "socks" thing - not shocks, but you have intrigued me.

puts new batteries in brain... that's better!

i would imagine that the coil of wire would have to be enormous though... with a very thin wire, maybe?

i guess that would work, but i'd prolly have to agree that you'd have to be ona pretty bumpy road to produce anything substantial.

it would totally work in south carolina! :eek::p

how far fetched would it be to make something like that and subject it to an automated device that compresses the shock over and over?

Krink
08-17-07, 07:56 PM
You boys read too much Richard Feynman. I was thinking more Rube Goldberg. Just some jolt-driven drive shaft to spin a Radio Shack generator. I figure you could at least run the radio driving down washboard with a decent cadence.

EthanYQX
08-17-07, 08:14 PM
When you have some magnetic field which is moving relative to the position of a coil of wire, electricity is produced. What I was thinking about works on the same principle as a rotary generator like you might have, or a power plant probably uses. Except my thoughts were to have a linear motion setup instead of rotary.

I just have to say, I think it could work and either way it's a genius idea.

phantomcow2
08-17-07, 08:57 PM
You boys read too much Richard Feynman. I was thinking more Rube Goldberg. Just some jolt-driven drive shaft to spin a Radio Shack generator. I figure you could at least run the radio driving down washboard with a decent cadence.

uuuuuugghh, I remember the last few weeks in my physics class was the "supplemental unit". That is, quantum electrodynamics. We used RIchard Feynman's book as the text book. It was pretty frustrating and that offered some very mind boggling and counter intuitive concepts. After hammering away though, it makes a lot of sense and is a unit which I remember more than any other in that class.