DIY suspension generator / regenerator
 

We all know the up and down motion of our suspension is just wasted energy (or at least we do now that I just said it) :). Anyway, Darin posted a while back about Tufts University electromagnetic shock absorber. It sounds like this shock absorber has a reasonable shot at completely eliminating an alternator unless you drive on roads of glass (haha, yeah right). So, how can we use their fancy design and make a cheapo DIY version? Lets get some ideas out there. This sounds like a good area to look at for 'free' energy.

My idea is to use a device similar to one of those shaker flash lights. You would mount a magnetic post somewhere on your A-arm and that would go up and down with the suspension travel. The coil could be mounted on an arm that is attached to the frame. The up and down motion would generate some electricity and it could be fed to charge the battery. I'm not sure on the specifics of how the shaking motion actually produces electricity, so you'll have to excuse my ignorance there. However, those shaker lights are cheaper than dirt, so I'd think we can make something up and keep it on the cheap.

What can you guys think up?

Here is some info on how the shaker flashlights work. As you can see, its a really simple device.

HowStuffWorks Autopsy - Inside a Shaker Flashlight


For those who know a bit more about electronics. How could we beef up this design to crank out more wattage? Is it just more coil windings and/or a stronger magnet? Or, are we looking at multiple coils and/or magnets?

Think of it as a linear alternator. In a typical alternator, the coil spins around, whipping its electromagnetic field through the stator windings. The shaking motion you refer to would be the same way of getting windings to pass through an electromagnetic flux field.

i live on a dirt road, and we still have concrete highways with expansion joints. i see potential........


take apart a shock, and mount the magnet on the piston where the oil seals would be. put the coil around it.

i wonder how much power one of those flashlights "bridge rectifier" could take? i have one.


its too bad i don't know much about how electronics work. i have access to a few cordless sawzall's, and some brush motors for commercial vacuums. all just sitting with broken parts, because it was cheaper to replace than repair.

Would the shaker be the best way to recover the energy? I pictured something similar to a shock absorber with an external reservoir. The motion of the shock moving up and down forces the fluid back and forth into the reservoir, while spinning a little generator in-between.

The shaker probably isn't the best way, however it is a very doable way. I dunno about you, but I don't have the means to put together an external reservoir setup with a turbine generator. ;)

Hmm... How about a bicycle air pump? They even have the ones with the check valve that pump air in both directions. Most are good to about 100 psi, and the foot-pedal operated ones seem to move a decent amount of air, so gang them together and connect them up to an air tool (grinder? screwdriver?) to drive a small generator. Kinda Rube Goldberg, but it might work.

sorry to burst your bubble but mit beat you to the punch...
MIT shock absorber increases fuel economy

Levant Power Corp is the new company
Levant Power Corp.

In their testing so far, the students found that in a 6-shock heavy truck, each shock absorber could generate up to an average of 1 kW on a standard road — enough power to completely displace the large alternator load in heavy trucks and military vehicles, and in some cases even run accessory devices such as hybrid trailer refrigeration units. the group, which also includes senior Zachary Jackowski and alumni Paul Abel '08, Ryan Bavetta '07 and Vladimir Tarasov '08, plans to have a final, fine-tuned version of the device ready this summer. Then they will start talking to potential big customers. For example, they have calculated that a company such as Wal-Mart could save $13 million a year in fuel costs by converting its fleet of trucks.(taken from the first link)

it sounds really promising,however idling will be an issue

No bubble to burst. :) I know its been done before. I'm just wondering how WE can retrofit our vehicles to use it.

Extended periods of idling may be problematic without deep cycle batteries, however starter batteries would probably be fine for the majority of drivers.

The way electricity is made is fundamentally by pushing electrons out of orbit continously. The magnetic field sitting still displaces them but it just creates a minor voltage difference. If you move it you can make a flow.

You have to move the magnet in the direction with the right hand rule. Curl your fingers around the palm around the coil with your fingers pointing into the middle with the direction of the magnet. The current will flow in the direction of your thumb.

That said. . .the super easy effective way would be to put tons of copper coil windings around the actual spring and just mount a large magnet on either end(top or bottom, make sure you don't make it long enough to strike the other side under heavy load).

The up and down motion that the springs absorb would induce the current.

Its kind of simple. . .copper wire around springs(lots) and a really powerful magnet. Neodynium(sp I'm sure). Test it on one of your springs with magnet and then put a DMM and push down on that tire(jump on the chassis there if it will take it) and watch the output reading. . .

For a normal car I'd expect a max of 60 watts per tire. . .Although if your zorber is totally shot like a 86 stock buick town tank you could get a whole KW!

my vote is for 4 shocks with a central turbine. although the efficiency may be way down with that

According to an article that I got from a coworker, the MIT team calculated the following:

1 cm of suspension travel
1.5 Hz
spring constant of 160,000 N/m
in a 3000 lb vehicle

Add this all together and you get 1.45 kW available from the suspension.

Now, there will be massive efficiency losses of course, but that is a LOT of power to tap into. The average car needs ~300W to run. So, our system would only need to be ~20% efficient to power a vehicle. If we wanted full alternator output (60A for my estimate) it would need to be ~50% efficient. That might be a bit tougher, especially when you lower the weight of the vehicle to what we normally drive here. Obviously, a heavier vehicle will produce more power.

Hi,

If this kind of suspension was combined with wheels/tires that do not absorb ~1/2 of the motion (and they would provide much lower rolling resistance), then more of this "bump energy" could be collected.

During idling, the driver (or driver+passenger ;) ) could jump up and down inside the car, working the suspension...

I was actually flipping through this month's popular science and it was one of the major articles. I was rather surprised. I guess someone else got their pop-sci before me.

The idea is particularly useful for you EV folks. Electrical drain from ICE engines is a nuisance and eliminating it would increase mpg. . .but in an electric that kind of "free" energy is enormous(especially at such a low cost compared to solar).

using mit's calculations how far would you get in an ev? i am aware that forever isn't an answer, and a geo doesn't weigh as much as a HMMWV, but say you take an ev geo with a with a 50 mile range and add these shocks what will it amount to on average?... how ever free energy is still free energy and awesome at that.

IF you did it the high-teck MITten way you could get an extra 3-4 miles per hour. You'd get roughly an extra KWHr/Hr and as far as I can tell thats 3-4 miles. Its not huge but it really is free, like sunshine.

If you did it the really easy way with coils around the springs and a magnet mounted on a shaft inside the springs you'd probably get about half that. . .but you could do that whereas the hydraulic fluid and. . .would be heavy and not easy. Better off just spending the time and money you would spend on that system and getting a truly enormous magnet for each coil.

I might test this out this weekend. . .depending on what ends up needing fixed at the shop this weekend.

The only problem with the coil and magnet idea is you're still using the shock absorber to dampen the vast majority of the up and down motion. If you use a hydraulic cylinder (as a shock absorber replacement), you can capture 100% of that energy.

that is cool. I am definitely going to try this ASAP. I just showed my students how to make electro-magnets in class last week, this is the same basic principle.
Electricity into a coil of wire = magnetic field
Magnetic field into a coil of wire = electricity

It would be awesome if we could ditch our alternators with a few of these!

so... if you had these and a solar roof panel you might be able to net 4-5 miles given that you park in a sunny area... over several days... if we take the high end that would give an ev 10% in range... i know that wont translate into a longer range vehicle, but thats cool

"I have to go drive the Electro-Metro over some speed bumps to recharge it. Back in a few..." :p:thumbup::turtle:

OK... a thought here. Ignoring the hydraulic fluid idea (for simplicities sake) and sticking with the electrical design, this wouldn't be able to actually act as a shock (no dampening effect) it would have to be in addition to traditional shocks. So what if we mounted 1 end of the electrical "shock" to the chassis, and the other end to a pivot, with the pivot being connected to the axle/a-arm, etc. The hardcore desert offroad guys do this when they want huge travel number in the rear without cutting the bed up for long shocks, they use a pivot so that they can run shorter shocks for the same travel, we would want the opposite, more travel (of the electric shock) then the car is actually moving.

I thought this would be the dampener. Producing an electrical current requires work, so there would be a force slowing the up-and-down motion of the wheel.

The linear generator will provide resistance based on velocity, creating a damping affect. Due to the complex valving inside of modern shock absorbers, which open & close valves based on velocity as well as bypass valving based on piston position, I dont think you can eliminate the regular damper. I also don't think you can eliminate the alternator, but the load certainly can be reduced.

You could use a linkage to increase the movement of the linear generator.
Neodemium magnets would be a nice touch.

Don

I like the idea of replacing the dampers in the suspension with a system that forces the hydraulics through a generator setup. It could easily be designed to generate electricity regardless of the direction of travel with some creative use of diodes in the circuitry design.

I wonder how Bose's Linear motor suspension system works. It may produce electricity when it hits bumps, but I don't know for sure. All I know is that it is said to create the smoothest ride around. I think Mercedes is going to be licensing it.

It would be very easy to make the hydraulic motor only spin one way. The use of a few check valves does this. I can draw a diagram if ya want.

Actually. . .the amount of dampening you create out of the linear motion magnetic and coil is directly proportioanl to magnet strength.

Its how roller coaster breaks work. they use the rails as conductive surface and place ridiculous near .1 gauss magnets(broken up into sections to create slow deceleration).

The amount of power you create is directly proportional to the amount of power needed to push.

If you don't think the dampening can be had go try and push the shaft on a generator while its hooked up to something(a light bulb). Its entirely possible to do this in a way so that the springs are bypassed and the wheels only move a few cm up or down.

The amount of dampening is again directly proportional to the strength of your magnets and the amount of coil(really the amount of power).

I'm not saying you guys are wrong about the dampening effect, but I don't think you are right either. lol Please explain to me how a magnet inside of a coil of wire produces any sort of dampening.

A magnet inside of a coil of wire creates no dampening or resistance when it moves in the coil (like a shaker flashlight). I mocked one up quick today, a couple of neo magnets inside of a coil of wire. Shook it, and it made about 80mV.

As far as I can tell you guys are comparing this to a motor, or linear motor where you are putting electricity though the coil which will create dampening when you slide a magnet through the coil, because you are really just making an electro magnet. But that isn't what would be happening here.

When you create current in any form of wiring you create EMF.

Its called self-induction. You create current in a wire with a magnet. The instant after you do that the wire creates an opposing EMF in the opposite direction, equal to a substantial fraction of the force you originally issued to the magnet.

To discover how this works out we use a quick check with a "right hand rule." If you point your thumb in the direction of positive current and your palm on the coil your fingers will curve in the direction of the EMF provided from the coil(if you run power through it).

If you run a magnet through the coil it will generate a current. . .and the flow will force a self-induced EMF in the opposite direction of the travel of the magnet.

The resistance I'm speaking of is how alot of dials work, specifically the ones in analog volt, amp meters.

The amount of EMF self-inducted resistance is proportional to 2 things. The power created from the original EMF flow and the material of the wiring. A theoretical perfect wire would perfectly oppose the EMF and it wouldn't move. But we do not know of any such perfect element, nor do we have any perfect wires of elements we do have. If you doubt the dampening effect I can give you a quick lab to demonstrate it.

Get a conductive metal sheet and hang it on a rope. swing it like a pendulum.

Repeat but place two large magnets on either side(not close enough to tough and viced down). If it swung 10 times before slowing substantially it will make it through. . .maybe 3-4 passes before essentially stopping.

The stop time is even greater if you use a copper wire on the end and run a diode or a couple of diodes at the pivot for the rope. To prove that it has nothing to do with the magnets attracting the metal take the metal and drill holes in the metal to make it look like swiss cheese. repeat. The swiss cheesed metal will swing as long as the metal with no magnets. The reason is its not generating true electric current(since its not a coil and you aren't using the electricity) its generating an eddy current. The current is flowing in the metal and making it warm and resisting motion and thats it. The holes kill the eddy currents of the EMF generated electron front. A rope with a winding of copper coils in the same experiment(much harder because you have to make sure the magnet doesn't actually touch the coil and it needs to go through the middle) will do the same thing.

If you want something else. . .Go try and turn your alternator with the battery disconnected and the lights on. Turn the lights off and try it.

Also if self-induced EMF didn't exist, every generator on the planet would violate the 1st law of thermodynamics as well as most statements of the 2nd. The joints in high power applications like power plant turbines are extremely low friction because it costs them alot to run and they want to squeeze every penny they can. If you disconnected those turbines and cut the flow off they would spin for at least an hour down from 3600 rpm. While connected to the grid it takes just minutes depending how big the generator is.

Yea, your right, that makes sense. And turning a motor with a load is definitely harder than turning a motor without a load. I've never experienced this in a linear sense though... I guess the things I have used just are not robust enough for me to really sense the dampening.

On that note, in order to dampen a car, wouldn't you need some serious power coming out of this thing?

^_^ yes.

In my Tech physics 2 course we had access to a .5 gauss magnet( 1 gauss is the same electro-magnetic pull as the Earth's core) and a couple of coils. We of course had to empty our pockets of debit cards and electronics or it would ruin them. But the coil was a little shorter than extended suspension springs and you could definitely feel the EMF fighting back when you pushed it around(was a u shaped coil). You could also feel it stinging your fingers finding the path of least resistance.

I think the standard equipment running in a car would be enough to do proper dampening, but i'm not sure. IF it produces juice in an easy layout it would be worth it to get a deep cell, or another small wet-lead acid and let it bleed down to about 85% for the deep and let the constant rocking charge it up. You'd need to reset a battery charger not to kick on until 85% charge of the deep cell so you could ensure you had enough place to. . .power sink?(heat sink?)

Hopefully it would discharge to power the ignition and things while on smoother surfaces and then run everything independently and recharge the deep cell for the next smooth section.

This could lead to some interesting problems... Make sure you take out your wallet when you go to work on your car.

Besides that I think this idea has great potential.

Are you sure about that .5 number? I have little button-sized neo magnets that are rated at 3400 surface guass.
K&J Magnetics - Products

I might have the wrong scale. There are two. . .one is the Si convenient unit which is something in the form of kN of force, and the other is the one for practical everyday use(because its alot smaller, think like farads everything is really small compared to one farad.)

Obviously you wouldn't want to use a magnet that powerful, but the field drops off exponentially anyway. that magnet(it was the old magnet from a NMR scope) would only destroy your things if you were within arms reach. So even using one that powerful you would be fine so long as you don't change your tires or pressurize them. I'd recommend either somegood sized neodyns or a big block of those cheap ceramics and pack them close to the spring itself.

edit: the term I wanted was Tesla, The gauss is what physicists invented to get their labs to buy big ones("I want a 1 Tesla magnet and it costs 500K", president of college, "500K for 1 tesla. . .no" attempt 2 "I want a 3.5 million gauss magnet for 500K," "oh! 3.5 million gauss for 500K, thats a steal.")

Thats how the joke goes anyway.

I did a bit more searching. IMO the best way to go here is hydraulic like I said before. I ran to the local farm supply store and took a look at their prices on cylinders. It looks like for a 2" cylinder with ~8" of throw, you're looking at $70 each. Compare this to the price of a strut and you're actually coming in fairly cheap. Now, you just have to find yourself a hydraulic motor off ebay. They go for less than $50 from what I've seen. Add a few rubber lines, some hard lines, and a bunch of check valves and you're almost done. If your car needed new shocks, I don't see any reason not to try it.

thinking on those KERS (XD) suspensions... I think that for using them you need to couple with some kind of battery, like the capacitor in the flashlight.
You charge the capacitor applying a shake for some seconds, charging the capacitor.

LED that doesn't consume so much, so a capacitor is ok because is relatively fast to charge and slow to discarge.

In a car, it's difficult to use them because you need to apply a continous energy to the batteries to charge them (ironic - > like shaking for 1 hour the suspensions) to use it for something really mileage-increaser.

That's my opinion, I have yet to study EMF >.<"

Now combine that with some 65 psi truck tires and adjust the damping to compensate and you have even more production capacity. :-)

If you went the easy way (wrapping the springs with wire and mounting a strong magnet on the shock absorber, from what I understand from this thread), about how much would materials cost to do all 4 wheels?

I would assume you would want some thinly insulated copper wire, to prevent the elements from causing corrosion?

This sounds like the most promising area for energy production, although it depends on road conditions. California has some pretty crappy roads so...

Combine this with a thermoelectric generator on the exhaust/catalytic converter and you'll really have something going.

Hi,

I'm wondering if a hydraulic system wouldn't be a better way to go? Then, there would only be one generator, if all the shock absorbers feed a central generator. Shocks are already hydraulic, so the dampening control would come from the pressure to spin the generator. There could be a small pressure bladder that would absorb the "excess" and then the generator could use it to charge over some slightly longer time.

With this system, you could also get ride leveling, and height adjustment, too. Both are important for good aerodynamics.

And I'll add again that if the tires/wheels were engineered for minimum rolling resistance, the suspension would do (almost) all the dampening (as opposed to the inflated tires that do about half of the suspension now!) would be done by the hydraulics, and this means more power could be gained! (Rather than wasting it as heat in the tires.)

I rather like this idea... if I ever get around to building an electric car, I might try it out.

In fact, I might try it with air shocks in my Taco... As you hit bumps, the pressure in the shocks goes up... Tee off the inlet valve (where you pump them up) and put a small turbine in one line, with a check valve, into a bladder, then loop it back to the shock with another one-way flow check valve... as the pressure in the shock increases, it can expand out through the turbine line, into the bladder. Once the pressure decreases (shock rebound) the pressure in the bladder exceeds the shock, so it will equalize again, blowing back into the air shock.

Similarly, one could use hydraulic pistons with turbines, and vary the load on the turbines to adjust the suspension's stiffness and response. Imagine sports-car like handling from your old Volvo Wagon?