Using flywheels to increase FE
 

Ok, so I saw this mentioned in the thread about the powered trailer and thought I'd start it's own thread because it's a very interesting topic and I haven't seen it covered here as of yet.

Using a large, heavy flywheel on cars to increase FE. First off, are there any manufacturers who actually make these. I know they make lighter ones for racing applications, but I would think that heavier ones would be harder to find because it's more of a niche market per say.

Also, what about making a trailer that simply encloses a very heavy disk that is connected to the wheels of the trailer via a gearing system that would keep the disk spinning long after power from the engine was cut off. I was thinking about this because it would GREATLY improve the ability of a car to do huge gaps of coasting between accelerating while EOCing. The only thing that would be a concern to be would be getting the big lug rolling at first. Since it would be many times heavier then a standard car flywheel, how would you overcome the effort that is needed to get it spinning at first?

I'm sort of thinking of those push cars, the toy cars you push and then when you let go they have a geared flywheel inside that keeps it going for a good time afterward, sort of like a kinetic energy engine almost that would just store up all the energy you created by accelerating and then release it over time.

And as always, :turtle:

There were experiments with this in the 1970s as far as I know. The flywheel was in a vacuum chamber, otherwise the air drag on the flywheel would rob a lot of energy. I think the use of this was regenerative braking. That would be a good use of the trailer, too. If you have to put useful energy into the flywheel, there is no advantage. If you can store energy that would be wasted, then great.

As far as how to get it spinning: Variable displacement swashplate pump on the trailer wheels, driving a hydraulic motor on the flywheel. The efficiency is not great, but neither is a generator> controller> flywheel-motor combination. With the swashplate flat, no fluid is pumped to the motor. As the swashplate tilts, more fluid goes to the motor. I think an additional pump and motor would be needed to get the energy out of the flywheel again. Electric clutches could disconnect the hydraulics when not in use to reduce parasitic loads of the hydraulic system.

Disadvantages: weight, gyroscopic effect, overspeeding the flywheel causes rupture.

Hm, ok, so your saying that the energy needed to be put into spinning it up eat up the advantages of having it spinning.

Why is the gyroscopic effect going to be a problem with a flywheel on a stationary platform? If anything it will make the trailer more stable, wouldn't it?

If you can "spin" the flywheel by braking it is a "good" idea, as in it "could" work. But, like ttoyoda said, if you are going to expend the engine more to get it spinning you will in the end use more energy than you will gain.

Well the trailer is not going to be stationary once the car/trailer is moving. If you suddenly drive onto a section of the road that has a sideways tilt the trailer will want to stay level, i.e. pick a tire up off the ground. Also as you add and remove energy to the flywheel (speed it up or slow it down) you will have the trailer want to move in an equal and opposite direction.

Actually you don't want the flywheel to be heavy: you want to make it out of a high-strength material like carbon fiber, so that you can spin it really fast. Getting energy in & out isn't a major problem: embed some magnets, and it becomes the rotor of a motor/generator.

There's quite a bit of research work going on in this area. Just do a search on "high speed flywheel".

Do you happen to know what the storage efficiency is compared to capacitors or battries?

After reading several articles about flywheels it appears that they are best used for providing acceleration rather than constant power. It has to do with how efficiently energy is first transferred to and from the flywheel vs the equivalent amount to/from a battery. The ideal hybrid system would have a flywheel the provide accelerative power and a battery for constant running. This article sums it up pretty nicely:

http://www.hybridcars.com/related-te...l-hybrids.html

This doesn't look like something a backyard mechanic could safely tackle. The forces involved are huge and dangerous if sufficient safety precautions aren't employed. Back in the '90s Chrysler tried, and failed, to build a hybrid flywheel race car. Just google "Chrysler Patriot".

Well, don't take what I say as gospel: I'm just going by some reading & a physics background. With that caveat:

Flywheels seem to be very, very efficient for short-term energy storage. That is, you can put X amount of energy into one in a very short time, and get out something like 99% of X minutes or hours later.

Batteries are less efficient at input/output: a larger fraction of the energy is wasted as heat, and they are more limited on the rate. On the other hand, they'll store the energy for weeks/months with little loss.

With capacitors, the problem is the exponential nature of the energy output. Without some sort of switching device, the energy all wants to come out in a rush.

A Capacitor works almost exactly like rechargeable battery.
Once it's charged up, it will discharge into the load at about the same rate as a battery.
(That's controlled by Ohms Law I=E/R).

The problem with caps is, they don't hold a lot of electrons. The run out of juice a lot faster.
A cap that would do the same job as your standard old car battery would be as big as a house..

No, capacitors discharge as 1/e^t, so after one time constant t, about 63% of the charge flows, in the second time constant 63% of the remainder, and so on out to infinity. Check any basic physics or electronics reference, for instance here: http://www.kpsec.freeuk.com/capacit.htm

Ok James
 

So, if I had a 10,000 farad capacitor charged up to 9 Volts and I connected a 9 ohm resistor across it, I wouldn't get 1 Amp of current flow when I flipped the switch?
Of course the voltage would drop over time..

http://www.kpsec.freeuk.com/images/discharge.gif

That's why I said "A Capacitor works almost exactly like rechargeable battery."

If someone could come up with a cheap 10,000 farad capacitor the size of
a AAA cell, then all our battery problems would be over..
It would be the ultimate rechargeable battery/cap.. :D

this post reminds me of a new motor i saw on BEYOND TOMORROW (discovery channel). in fact i believe it was in the new recently..few months ago. an australian inventor has built a motor that runs on compressed air. sorry but that's all i recall about it unless i find more 411

Here's the thread:

http://ecomodder.com/forum/showthrea...09-a-1143.html

No. If you look at instantaneous current flow, it will follow the same exponential decay curve as that voltage plot. You'd have a current flow of many amps for the first fraction of a second, declining to a fraction of an amp after several seconds. A battery would supply nearly constant current/voltage until it's depleted.

jamesqf,
I believe you may be mistaken.
From V=I*R we get I=V/R. Putting in 9 for the volts (V) and 9 for the ohms (R) we get 1 amp (I). Now as the current flows, the voltage in the capacitor drops, so the current gets lower with time, perhaps along the lines of a time constant RC. But the maximum current at the start when the switch is first closed is 1 amp.

If by "many amps", you mean 1 amp, then you are right. The usec the switch
is closed, there will be 1 amp of current flow I=E/R (9 Watts of heat will come out of the resistor) and then over time, the voltage (and current) will drop off. And the heat will drop off slowly too.

To get a lot of amps flowing from the 10,000 farad capacitor, you could just
short it out with a heavy jumper wire. But, I would avoid being in the area,
since that 9 volts and some really high amperage just might vaporize any undersized jumper. :eek:

When I worked for NEC, we had 1.0 Farad 5V capacitors on some of the test gear. The caps were installed to preserve the data in the memory chips, in case of power failure.. They were used because the designer didn't want to use a Nicad battery. They worked very well. We never lost any data.

i realize i'm way late on this but the idea of a flywheel is basically as an inertia drive. induce spin, as its spinning it holds onto the energy as inertia. when you pulse and glide your basically doing the same thing.

as you speed up you gain momentum, when you take the car out of gear and just let it roll you are useing up the cars stored momentum/inertia

I hate to be the bearer of bad news. . .

If you have a huge flywheel(or even a small flywheel spinning very fast) and you turn or tilt itin any fashion its going to go haywire. . .There is a video of some people playing a trick on a bus boy(back in the 30s or 40s) where a large low friction flywheel is inserted in a suitcase. The wheel is accelerated to high speed and then handed to the unsuspecting carrier. When he rounds the corner it yanks the suitcase out of his hand and jumps straight up and into the wall.

If you change the direction of the wheel an equivalent amount of force(however much energy is in the wheel) will be applied 90 degrees opposite and out of plane (read cross product) from the original turn. So if you turn left the trailer tries to climb up, right it digs into the pavement and tilting it causes it to swerve sideways.

If you were going to go completely straight(no tilting or twisting of ay kind) then it would work fine.

That's a hilarious prank... please find the video :)

I was under the impression that F1 was going to go to a flywheel hybrid design... maybe it was just smoke in the breeze, but its a novel concept...

So worst case, all you need is a gimbal mount...

I have thus far been unable to locate the "video" of the bellhop getting jerked around.

The problem with finding this particular video. . .is its a GIF. I found it in another forum(that thread was devoted to creating an electrical turbo off of large saw blade, for some reason there was avilable electricity). The reason that idea also wouldn't have worked very well is because the blade would have to spin very fast and would be reasonably heavy, so turning the car would cause enormous torque on the engine, mounts and blade itself.

Any form of translation of the energy will force the flywheel to rotate one direction or another(or apply torque up or down if the axis itself is tilted). Unless the flywheel can spin freely all the time in all directions it will dissipate all of its energy very quickly trying to go the new direction.

It would be rather complicated to apply force to the wheel or recover it because the wheel if turned or tilted will begin spinning on its mounts. So instead of it resisting for a moment and then assuming the new direction it will continue to resist/accelerate until an equal translation has been completed.

One of two things has to happen to avoid the wheel losing its KE A.) the mounts have to isolate car motion and the car "rotates" around the flywheel or B.) the flywheel is allowed to rotate freely in all directions to avoid dissipating energy. If you had some very low friction bearings you could attach a generator and drag it out as electric power but it may be difficult to complete a circuit on something that rotates like a sphere with no permanent predictability.

Anything that's spinning around a fixed central axis with no load becomes a gyroscope. So, when he went to turn the suitcase, the spinning motion of the flywheel wanted to maintain its direction of travel. This, to the bellhop, caused him to let go, which then made the suitcase continue traveling on a linear path tangent to the circle with a radius equal to the curve of the turn he was trying to make.

Let's think about this a bit. First, if you want your flywheel to be at all efficient, it's going to be in a vacuum, using magnetic bearings, and the coupling is going to be an electric motor/generator. (You can look up recent research on flywheel energy storage for more details.)

So if you have the flywheel rotating in a horizontal plane, you're not going to have any flywheel torque from driving on level ground, only if you pitch up or down, or from side to side. So you mount it in gimbals (like a kid's gyroscope toy), with room to tilt, and some hydraulic dampers at the end of travel. Do this right, and it maybe even becomes a safety feature, the anti-rollover device :-)

flywheels
 

Chrysler abandoned research on flywheels do to safety and liability issues related to bearing failures and the catastrophic events that would follow.Should the rotor bearings fail and lock the flywheel rotor,the rotor would either tear itself out of it's anchorage energized by gyroscopic forces and would continue a reign of terror until all kinetic energy was spent,or the entire vehicle would spin end-over-end,or pirhouette bumper-after-bumper.There was no way to control it.No way to contain it.Way scary!!!!!!!!!!!!!!!!!!!

"Chrysler abandoned research on flywheels do to safety and liability issues..."

Really? Or was that just an excuse? After all, they (like the rest of the not-so-big any more 3) sure managed to find reasons to give up on every efficiency-increasing device that came along, from electric cars & Stirling engines on down to just simply making smaller cars.

If you do some searching on high-speed flywheels, you'll find there's quite a bit of ongoing research, with systems having been installed in (or planned for) in busses and trains.

Really?
 

I thought perhaps noCo2 was actually serious about attempting this on own car and I felt an obligation to share info which might broaden their view.I'm all for progress but not at the cost of innocent lives.Chrysler's report carried grave implications about flywheel technology and unless noCo2 has their own test track,I don't want to be within a country mile of their experiments."To know and not tell makes cowards of men" Abraham Lincoln.

You know, it always puzzles me when some new technology gets slammed due to some remotely-possible safety problem, by people who blythely ride around in close proximity to 10 gallons or more of highly-flammable liquid fuel which is perfectly capable of turning their car into a blazing inferno if things go wrong. And it does happen, even if not with quite the regularlity that Hollywood chase scenes would have you expect :-) So why haven't we abandoned the internal combustion engine because of these issues?

why
 

If the main-bearings of the crankshaft seize on an IC engine,the car merely stops in it's tracks,something a nearby defensive driver could adjust for if encountered.This would not be the case for a car with un-predictable behavior.

On the other hand, if the driveshaft U-joints (on a RWD car) happen to fail, other drivers can find themselves trying to dodge a 6-foot steel shaft bouncing down the road. Or if you drop a transmission or rear end, or a wheel falls off - all of which I've seen happen - then what? All of these things, and many others, can and do happen, yet the danger doesn't seem to bother anyone.

I've actually had a driveshaft come off my 1979 Plymouth Volare.... it was definitely a great ride, since the car almost endo'd before the rear joint broke and sent the drive shaft flying into an oncoming line of traffic.

Noone was hurt, nothing was damaged (other than my car.)

Changed the yokes on the axle and transmission, and installed a new shaft with new bearings, ran it once, and the damn car wouldn't start again after that.

I've had a wheel come off, and go rolling down the road. (Come to think of it, I've had it happen twice, once way back when I was in high school.) Again, no one was hurt, but that's just pure luck: it easily could have been otherwise. Then there's my ex's pickup, which caught fire as she was warming it up one winter morning.

The point is, there are all these real things that can and do go wrong with current automotive technology, but people seem to have become so familiar with them that they're accepted as just natural, and so discounted. Get some new technology, though, and they start imagining all the things that conceivably could go wrong, wildly exaggerate the risks, and so wind up making unreasonable decisions.

Speaking of wheels falling off...

Riding in my friend's 79 K20 Chevy... lifted 16" (12 suspension, 4 body) with 44" gumbo tires on it... We're doing about 60 down the road, and all of a sudden the front left corner dips down a bit... seems like we broke a shock, so we don't stop... keep going.

Less than 2 seconds later, the 44" monster Gumbo Super Swamper rolls in front of the truck, and bounces off into the field, at 60+MPH. We come to a complete stop, pulling off the road as best we could, and the hub is still 10" from the ground.

The tire is 200 yards out into the field, there is no way we can get it back up to the road by ourselves and get it on there, so we call a friend, who brings another friend, and they drive in front of and behind us with 4-ways on, while we cruise home at 15 MPH on 3 wheels.

Honestly, that experience was better than the mudding that day was.

Moral of the story: after mudding excessively, check your vehicle over before going home.

How about just putting heavier wheels on your car? I have a set of 15" alloy rims that weigh ~20lb each and I definetly notice a lack of acceleration with them on, compared to my normal 14" steel rims and tires. I should test it but given equal rolling resistance heavier wheels will help a bit with the gliding phase. Of course there are all sorts of downsides to heavy wheels but none of them stop the ricers from putting the biggest rims they can fit on many small cars.
Ian

at you
 

Have you ever had an entire car come at you,flipping end-over-end?

A coworker of mine did a few years ago. Not pretty. He was ok, though.

I like the idea of the flywheel, if mounted horizontally. The only practical issue would be hills. Safety issues are safety issues, but let's assume that safety wasn't the issue. Who's a math major around here? What size and mass of disk rotating at what velocity would be required to move a city bus from a stop? What would the best methods of energy transference be for both energizing the disk and providing motive force to the vehicle? Would it be worth it?

I can see this being one of the many possible solutions for hybridization of buses and delivery trucks that stop and go frequently and don't do too much mountain climbing.

I had a car come flying at me on a track.. that's about it. Not nearly as scary when you're semi-expecting it to happen.

Food for thought - Isn't the most wasteful event the initial takeoff time? So even if the flywheel's stored energy was enough to get the vehicle moving so the engine could take over, wouldn't that have a significant impact on efficiency? (For a bus, or a delivery vehicle, such as Postal Service trucks (which run on propane)).

I still use 13's or 14's, up to 16's, depending on what performance I want to see from my tires, and how much of the actual suspension duty I want my tires to see. My DD has had 16's on it, but never when they have stiff suspension.. I use my tires as more of a performance tuning setup than for style.

Also, there have been cases where a larger wheel/tire combination were actually less weight than the OEM config, and made sense for a particular application. It doesn't happen often.

Not flipping end over end, no. But spinning in circles 'cause the idiot driving didn't realize that 4WD doesn't improve your steering control, yes, several times. And what else is new?

Anyway, you're missing the point. You've made up some superficially plausible thing that could go wrong, sort of like the theory that hybrids were going to electrocute rescuers after accidents, or that magnetic fields from electric cars would cause cancer, and try to use that as a justification for not developing what might be a useful technology. The point is that if you bother to actually think about what's involved, instead of running in circles claiming that the sky is falling, you soon see that your superficially plausible threat is nothing of the sort.

Start with your basic thesis: that the bearings of a flywheel might somehow seize up, and suddenly transfer the momentum of the flywheel to the whole car, causing it to tumble end-over-end down the highway. The first problem is that a sensible energy-storage flywheel design uses magnetic bearings, spinning in a vacuum. There's no physical contact, and thus nothing to seize. Second, the flywheels are built of things like carbon fiber, so when subject to a sudden severe stress of that sort, they would harmlessly disintegrate into tiny pieces.

You know, you can actually look up these things on the web. People have built these sorts of flywheels, and destroyed some of them in testing. It's something called engineering, you know.

Even if the bearings were physical bearings, rather than magnetic, would the flywheel really contain enough force to actually flip the car? Probably not.

Considering the amount of horsepower it takes to lift the front tires of a 3000 lb car off the ground, that flywheel would REALLY have to be moving to create anything more than a "goose" to the car.

Also, placing the flywheel somewhere in the center of the car will create an offset " axis" effect, would it not?

IOW - If the flywheel is spinning in one direction, in the center of the car, on mechanical bearings, and contains it's full power capacity, then suddenly the bearings seize, and it just STOPS. Lets say it was spinning clock-wise, as you face the driver's side... so spinning toward the rear of the car.

Obviously, even with 100 HP of force applied instantly, the axis is the center of the flywheel, the contact point is the rear wheels, and the force is attempting to lift the front wheels/front half of the car, creating a bi-axial motion. (The car is trying to spin around the flywheel's axis, but the rear axle is stopping it, creating an axis between those two points.) Now, move the spinning flywheel to the rear of the car, just behind the rear axle, where it will be the least dangerous to passengers in the vehicle:

Still spinning backwards, stops immediately. This places the first axis ahead of the force axis, so that now that same 100 HP is trying to lift the WHOLE car, except the 100 lbs in the trunk area, and whatever weight the flywheel's assembly contained. It's not likely that 100 HP is going to be able to lift 1300 LBS 13 or more feet on an axis, allowing it to flip over, even once, let alone more than once.

Add to that: bearings don't just "seize", at least not to my knowledge. They create friction first, as they heat up, before failing, which would lessen the power storage capacity of the flywheel, and might also aid the theory that it wouldn't just STOP spinning all at once. It would begin slowing (as it would take more power to keep the flywheel spinning than it used to) until the bearings could cool enough to solidify and seize, which would create a less than impressive "jolt", rather than the full rating of the flywheel exploding into an axial force, sending the vehicle endo'ing down the highway.

Since HP can be seen as a property of force and speed, (HP = TQxRPM/5252) the slower it's rotating, the less power it will have, making even the strongest setup not able to do what some contend may happen. (Be reasonable here - Yes, maybe 1000 HP could do it, but that kind of power storage would be far too expensive and large to use for our purposes.)

Good reference to this - Mythbusters did an experiment where "Buster" was riding a motorcycle, and they jabbed a stick/pipe through the front wheel, stopping it instantly. The motorcycle became quite unstable, but did not flip. At speeds where the force was supposedly able to make the bike flip, all it did was drag the wheel. (That part doesn't apply here.)


It doesn't seem likely, as even the lighest street driven cars weigh at least 1300LBS, AFAIK.

Flywheels have to be used in pairs to avoid major gyroscopic effects, and the bearings have to deal with major forces between them. However, bearing failure is not a major problem - there can be two or three backup modes during failure. The usual concern is over disintegration - the NHRA used to mandate armour plate around the flywheels on dragsters. Modern, high-speed flywheels are made of composite fibers, and turn into fluff when they fail. Unfortunately, it is a lot of high-speed rotating fluff that wants to expand as much as any other explosion, and it contains all the energy of the "fuel," without waiting to be mixed with air. The armour is cheaper than when dealing with chunks, but it still comes to about as much material as an air tank to contain the same energy.