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Prototype Volvo Flywheel Tech Uses Car's Wasted Brake Energy

timothy posted about 7 months ago | from the price-is-them-mother-of-invention dept.

Transportation 262

cartechboy (2660665) writes "Sometimes we get carried away with sexy moonshot car tech--whereas most everyday gains are about reducing inefficiencies, piece by piece. Volvo's flywheel energy-recovery prototype is a great example of the latter--not to mention similar to one used in Formula 1 racing. The system recaptures energy that would be wasted in braking, like a hybrid does, to reduce fuel consumption by up to 25 percent. When you hit the brakes, kinetic energy that's usually wasted as heat is transferred to a "Kinetic Energy Recovery System" mounted to the undriven axle. It spools up a carbon flywheel that turns at 60,000 rpm to store the energy. When the driver hits the gas, some of the stored energy is transferred back to power the wheels through a specially designed transmission, either boosting total power to the wheels or substituting for engine torque to cut fuel consumption."

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Just like in Formula (2, Insightful)

Gothmolly (148874) | about 7 months ago | (#46595681)

This seems great for high or nearly-sustained speed driving, but what I really want is an electric only option from 0-15 mph, a "parking garage" or "traffic jam" mode that I can put my car into.

energy from BRAKING - best for stop-and-go (5, Informative)

raymorris (2726007) | about 7 months ago | (#46595751)

It briefly stores energy from braking and uses it to accelerate a moment later. If you don't hit the brakes, it does nothing. If you hit the brakes and stay at a low speed for five minutes, it does nothing.

When it works is when you stop (which stores energy), then go (which uses the stored energy). In other words "stop and go" traffic is EXACTLY what this is designed for.

Re:energy from BRAKING - best for stop-and-go (-1)

Anonymous Coward | about 7 months ago | (#46595811)

As long as it's not stooooop and then go, which is the case in most traffic jams I see. Also, the increased complexity, cost and weight might make the system not worthy.

Re:energy from BRAKING - best for stop-and-go (3, Informative)

Todd Palin (1402501) | about 7 months ago | (#46595925)

If you are a careful driver and plan ahead to avoid quick braking, and also accelerate at a very modest rate your benefits would be small with this kind of system. It helps compensate for aggressive driving but it seems like it won't benefit drivers that already are trying to get good gas mileage.

Re:energy from BRAKING - best for stop-and-go (1)

H0p313ss (811249) | about 7 months ago | (#46595985)

If you are a careful driver and plan ahead to avoid quick braking, and also accelerate at a very modest rate your benefits would be small with this kind of system. It helps compensate for aggressive driving but it seems like it won't benefit drivers that already are trying to get good gas mileage.

Very true of highway driving, less so for stop and go city traffic.

Fuck Hypermilers (5, Insightful)

Anonymous Coward | about 7 months ago | (#46596023)

I hate getting caught behind one of those "How slowly can I accelerate and still call it acceleration" types. Invariable on my commutes, it's those dickheads that do not understand that the lights are timed for NORMALS and cause a huge traffic jam behind them from stopping at every damn light. Yeah, you save a LOT of gas stopping at every light on the road instead of getting up to speed in a reasonable distance and getting the green. I have one road on my commute that has 15 consecutive lights. Pass the eco-nazis and I never have to stop. Get caught behind them and my commute time doubles.

Re: Fuck Hypermilers (1)

jovius (974690) | about 7 months ago | (#46596205)

Shouldn't you just leave a few moments earlier to catch the green wave then?

Re: Fuck Hypermilers (1)

Anonymous Coward | about 7 months ago | (#46596431)

Nope far more fun to screw with the morons that left 10 minutes late and are trying to drive 95mph through traffic that has an average speed of 80mph.

Those dooshbags deserve every slow person in front of them.

Fuck boy racers (4, Insightful)

Dr_Barnowl (709838) | about 7 months ago | (#46596247)

People who don't leave adequate braking distance and accelerate as hard as possible are the reason most of the traffic jams on my morning route occur. A single light touch on the brakes gets magnified into a ripple of progressively more urgent braking until you have traffic that grinds to a stop - no obstruction required. A few large gaps help to absorb this kind of thing and would keep the traffic flowing, but the few people who seem to think that tailgating people at beyond the speed limit until they give way and let the guy overtake you - so he can do the same thing to the next guy in the fast lane going the same speed - is acceptable make everyone else so paranoid that they are missing out on a particular piece of road that hardly anyone is willing to leave any space.

If everyone drove with a little more room, then the traffic wouldn't jam up so much, and paradoxically, people would get to their destination faster. The tailgaters are just spoiling their own driving party.

Re:Fuck boy racers (3, Insightful)

_UnderTow_ (86073) | about 7 months ago | (#46596329)

Translation: "If most people weren't stupid, we could have nice things"

Re: Fuck boy racers (2)

guruevi (827432) | about 7 months ago | (#46596745)

Scientific studies have shown the opposite though. People slowing down unnecessarily below average speeds is what causes traffic jams. Generally those that stand on the brakes the second someone in front taps off their cruise control with the brakes are the causes of the ripple effect.

Look at any section where lanes are reduced or split - people slow down (ok) but then there are those that slow down so much as to either fit in last minute that they slow down the entire side of the split that has less traffic or they always leave 2 18 wheelers of space between each other or practically come to a stop because of someone fitting themselves into that space (especially if they're on the phone).

Re:energy from BRAKING - best for stop-and-go (3, Informative)

Immerman (2627577) | about 7 months ago | (#46596039)

Not at all - if you hit the brakes at all you're throwing away kinetic energy as heat, no matter how aggressively or gently you do so. This system allows you to capture some of that energy instead and use it to accelerate again later. Unless you are in the habit of coasting to a stop without using the brakes or engine-braking at all this will reduce the associated energy waste.

Re:energy from BRAKING - best for stop-and-go (1)

amorsen (7485) | about 7 months ago | (#46596459)

Accelerating at a modest rate is not particularly an advantage in a petrol car. Petrol cars are only decently efficient under full load, so you want to accelerate quite swiftly, using as high a gear as possible. If you are driving an automatic, it will spoil that idea by "helpfully" shifting down when it detects that you are pushing the accelerator, so that only works in a manual.

Re:energy from BRAKING - best for stop-and-go (0)

cyborg_monkey (150790) | about 7 months ago | (#46595825)

which is why UPS is using these.

Re:energy from BRAKING - best for stop-and-go (4, Funny)

gnick (1211984) | about 7 months ago | (#46595939)

That seems to make sense and seems like an interesting idea. Can you express it using a car analogy?

Re:energy from BRAKING - best for stop-and-go (0)

bob_super (3391281) | about 7 months ago | (#46596231)

Sure, let me give it a try:

The heavier the car, the more energy there is to store when you stop.
So you add a device to store the energy for later.
BONUS: you just made the car heavier, which means you have even more energy to store.
So now you can restart from scratch easier using the stored energy, unless you didn't have energy stored and have to restart a heavier car.
But you can't have bad performance when starting, so you need a bigger engine.
BONUS: you just made the car heavier again
So you add a few more bars to protect you in case of a crash, what with all these heavy vehicles on the road, you know...
BONUS: you just made the car heavier yet again, man do you have a lot of energy stored in that bigger flywheel that you put in to better recover the bigger energy of the heavier car!
You're definitely saving a lot of gas, in stop-and-go traffic, compared to the other huge cars!

On the other hand, an econobox will get you from the same point A to the same point B for 3l per 100km (or over 60mpg) and cost a quarter of the price.

Of course, we can trust the average Joe to properly maintain a piece of hardware designed to rotate at 60000 RPM, right?
I'm looking forward to cars just blowing up when they come to a stop because unmaintained flywheels explode and shrapnel likes gas tanks, according to hollywood.

Re:energy from BRAKING - best for stop-and-go (4, Informative)

Bengie (1121981) | about 7 months ago | (#46596403)

Going from memory from many years back, there was a few very interesting points when I was reading about flywheel research for hybrid F1 racers

1) Something like 90%+ efficient at converting physical energy into rotational and back out
2) Decided to use carbon fiber because instead of turning into shrapnel, it disintegrates when it smashes into its cage
3) Added less weight than an extra person
4) Was able to supply 80hp for 10 seconds at max
5) Was able to quickly and efficiently capture energy, so you could slam on the breaks and get your 80hp for 10 seconds very easily
6) Increased fuel efficiency for F1 racers by 10%-20% because of lots of hard breaking followed by hard acceleration.


I'm sure other safety issues will bring down the effectiveness of these devices for regular car users, but there is a lot of margin to make it an overall win.

Re:energy from BRAKING - best for stop-and-go (0)

amorsen (7485) | about 7 months ago | (#46596549)

3l/100km is a myth. See The most fuel efficient vehicles [spritmonitor.de] .

The only ones that come close are 2 tiny diesel cars. Both have been out of production for almost a decade.

Re:energy from BRAKING - best for stop-and-go (1)

angel'o'sphere (80593) | about 7 months ago | (#46596663)

They are not a myth.
Perhaps you should read and try to understand what you link.
Quote: Please note that only representative entries are considered
Most cars that use 3l or less fuel are sold in very low numbers, that is all.

Re:energy from BRAKING - best for stop-and-go (1)

bob_super (3391281) | about 7 months ago | (#46596743)

I my point invalid if I write 4l (essentially 60mpg) or 5l (~50mpg)?

I point at the moon-sized battlestations driving by, don't stare at my finger

Re:energy from BRAKING - best for stop-and-go (4, Interesting)

Anubis IV (1279820) | about 7 months ago | (#46596593)

Actually, yes, I think we can, strangely.

Imagine you're coasting your way to the top of a hill and stopping at the top of it, with the brakes doing very little of the work in stopping you. By cresting to the top of the hill, we've effectively converted the kinetic energy you had into potential energy that can later be reclaimed when you go down the hill, and we've lost very little of that energy to heat from the brakes. That is, we can reclaim that stored energy to get a good chunk of the way back up to speed for a fraction of the fuel cost that it would have taken had that energy been lost.

In much the same way, a flywheel is capable of converting forward momentum into a form that can then be used later. You can think of it as an invisible incline under the car every time you hit the brakes, helping to bring you to a stop while storing that energy for later, and an invisible declination under the car every time you follow the braking with the accelerator, helping you get back up to speed without having to consume as much fuel.

(I'm now eagerly awaiting corrections, since I'm sure I misused terms and explained things poorly)

Re:energy from BRAKING - best for stop-and-go (1)

kyrsjo (2420192) | about 7 months ago | (#46596153)

According to the article, it holds the energy for ~20 minutes.

Re:Just like in Formula (1)

Anonymous Coward | about 7 months ago | (#46595783)

If you meant Formula 1, then no. Only Williams uses a flywheel based KERS (even that is a hybrid). Everyone else uses a battery, just like a Prius.

Almost there (0)

Anonymous Coward | about 7 months ago | (#46595687)

Now all you need are hundreds of little magnets around the outside of the flywheel, and a bunch of little switched coils surrounding the case. Then you can control the thing with a computer and you have a hybrid that doesn't have to worry about high end gear rations vs. low end.

Re:Almost there (1)

Mike Buddha (10734) | about 7 months ago | (#46596051)

Mazda announced they're working on a hybrid system that feeds no energy directly from the engine and has no battery. It uses regenerative breaking purely to charge up capacitors which then power a motor used to add power to the drive train. It forgoes a lot of the weight inherent in the standard hybrid setup. I'm curious to see how well it'll work. It'd be awesome if you could plug it in to charge up your caps before you took off for the morning commute.

2020?? (1)

ZorinLynx (31751) | about 7 months ago | (#46595715)

" “some form of KERS” would be inevitable on production cars after 2020."

I'm hoping that by then, electric cars (with regenerative braking) are starting to become the norm.

Really, 2020? With the pace technology develops, this might as well be Star Trek.

Gyroscopic precession (3, Interesting)

hubie (108345) | about 7 months ago | (#46595723)

Since you are spinning up a high-speed gyroscope, if you are braking through a turn I wonder if it effects handling in any significant way.

Re:Gyroscopic precession (0)

Anonymous Coward | about 7 months ago | (#46595823)

Some vehicles (delivery trucks) use hydraulic/compressed air as an alternative for energy storage.

Re: Gyroscopic precession (4, Informative)

Anonymous Coward | about 7 months ago | (#46595851)

This was discussed when flywheel KERS was added to formula one. The forces involved are not significant, and on a heavy vehicle (as opposed to an F1 car) would have even less effects.

Ultimately it is just a stop gap. Electric is so much more flexible than the complex CVT and fundamentally limited flywheel used in this. Which is why F1 all went to battery based systems.

Re: Gyroscopic precession (3, Informative)

necro81 (917438) | about 7 months ago | (#46596583)

The F-1 flywheel systems have a vertically oriented axis, so that the gyro forces are reduced.

The model demonstrated by Volvo has a horizontal axis, so the gyro forces will be greater and must be dealt with. Thankfully, it's pretty easy to quantify. If you get the flywheel spinning in the correct direction, you can even make the forces work in your favor to reduce roll during a turn.

Re:Gyroscopic precession (5, Interesting)

Anonymous Coward | about 7 months ago | (#46595915)

The Chrysler Patriot prototype in the early 90's had this problem. This was a vehicle that was being designed for the 24 Hours of Lemans. It had a gas turbine that ran a alternator, which powered an electric motor driving the wheels. Instead of a battery pack it used a composite flywheel to store energy. Initially the flywheel caused too much of a gyroscopic effect and it was found that you couldn't turn the car. The solution was to make the flywheel gimbaled so it could rotate as needed while the car maneuvered.

http://www.allpar.com/model/patriot.html

Re:Gyroscopic precession (1)

kyrsjo (2420192) | about 7 months ago | (#46596255)

I would guess the effect would be very much smaller if it is mounted so it's rotating in the horizontal plane (vertical axis), than if it's mounted with a horizontal axis.

Re:Gyroscopic precession (1)

Anonymous Coward | about 7 months ago | (#46596433)

In which case I wonder if it would give a benefit against roll-over?

Re:Gyroscopic precession (1)

Lumpy (12016) | about 7 months ago | (#46596453)

going up or down a hill when you brake hard will be entertaining.... Mommy, why is that car standing on it's nose?

Re:Gyroscopic precession (1)

steveg (55825) | about 7 months ago | (#46596491)

Um.

You're going to get this effect (under braking or acceleration) no matter what orientation the flywheel is using. In one case it will be precession, in the other it will be a straightforward angular acceleration. The vertical axis might work better when your speed is constant.

When you apply the brakes with a vertical axis flywheel, you are accelerating that flywheel which means an application of torque. The frame of the car will experience the opposing torque, providing a twisting force in one direction or the other, depending on which direction the flywheel spins. Drawing energy off the flywheel to accelerate the car will twist you in the opposite direction.

Counter rotating flywheels would probably solve the problem.

Brake Pedal (3, Interesting)

lgw (121541) | about 7 months ago | (#46595725)

I love this idea (and why has it taken so long to come to consumer cars), but please don't screw up the basic UI of a car the way some hybrids do! The brake pedal is for braking, dammit; simply lifting off the gas pedal should result in nearly coasting, unless I've deliberately put the car into a low gear for engine braking.

The hybrid I test drove (and I understand this is normal) would do regenerative braking up to the limits of that system on a simple lift-throttle, where the brake pedal was just the brakes. Talk about leaking the implementation details through to the UI! Don't do that!

For all I complain about UI designers, engineer-designed UIs are worse still.

Re:Brake Pedal (0)

Anonymous Coward | about 7 months ago | (#46595881)

On that note, how about some decent performance with the hybrids? This way, they are not causing traffic jams as they can't get onto a major expressway at any reasonable speed. Even the Jetta TDIs can get to 65 and merge safely, while some of the other hybrid vehicles cause massive panic stops when they enter an interstate below 40-45.

Re:Brake Pedal (2)

Collin (41088) | about 7 months ago | (#46595937)

This is less likely to be due to mechanic performance limits but rather due hybrid drivers trying to optimize gas mileage via slow, smooth acceleration.

Re:Brake Pedal (1)

Mike Buddha (10734) | about 7 months ago | (#46596083)

This is specific to Priussies*. I drive a Camry Hybrid and have no problem at all getting up to 65 lickety split.

Before I got my car I considered buying a Prius but couldn't figure out if the car was gutless or the drivers were gutless. Either way, the Camry was a much better choice for me. And cheaper than a Prius.

*A Priussy being the driver of a Prius.

Re:Brake Pedal (1)

mlts (1038732) | about 7 months ago | (#46596603)

What is annoying is the pulse and glide hypermiling thing... accelerating to 70, dropping to 55, repeating... supposedly is good for gas, but hoses traffic because of the speed changes.

The irony is -- it seems to be only Priuses. Camry hybrid drivers don't have that issue. Neither do the people driving the Lexus models that are hybrids. Neither do Ford hybrid drivers, nor the Insight/Civic drivers... it is just that one model of vehicle that seems to attract the people who tailgate the semis, pulse and glide, refuse to accelerate, etc.

Even more ironic... the Prius isn't that bad a vehicle. I've test-driven one and they go about the same as other small cars... not extremely fast, but not a Geo Metro either.

To boot, I can tack an inverter on the traction battery and have enough wattage available to jump start almost anything on the road with a charger. The inverter also comes in handy if there is a power blackout, since the Prius can be used as a fairly efficient generator that is decently quiet, and with the emissions on it, it puts out less harmful exhaust than a putt-putt generator of the same wattage.

Re:Brake Pedal (1)

gnick (1211984) | about 7 months ago | (#46595987)

Engineer-designed UIs are damned near perfect. As long as you're the engineer that designed them. And it hasn't been too long since you used them.

Yes - I am an engineer. And yes, I have outsmarted myself more than once. Go back to a 3-year-old project and think, "What was this person thinking??? Oh wait, that person was me..."

Re:Brake Pedal (1)

lgw (121541) | about 7 months ago | (#46596071)

Engineer-designed UIs are damned near perfect. As long as you're the engineer that designed them. And it hasn't been too long since you used them.

Ain't it the truth! It's hard to tell from modern software, but you really can make a UI that's easy to learn without being expert-proof! But now the sad trend is to simply remove every seldom-used control entirely - I'm sure "UI designers" will eventually achieve the same degree of uselessness as an unfamiliar engineer-designed UI.

Re:Brake Pedal (1)

steveg (55825) | about 7 months ago | (#46596325)

I haven't seen this. My hybrid (Ford Fusion) bleeds a little off the speed when I lift the throttle, but somewhat less than a regular ICE drivetrain would. The brakes, on the other hand, extract speed energy into the battery as fast as the battery can take it -- if I'm braking harder than that, it simultaneously applies the friction brakes. From a "user interface" perspective, I can't tell which part of the brake system is being used until I've come to a stop, when it gives me a "braking score" that shows how much of my braking energy was recovered. After a while you get a feel for how hard to brake to get the most back from braking. As a bonus, brake pads might last you 60 or 70 thousand miles.

I'm pretty sure the reason the car doesn't freewheel completely on throttle lift is so that the car will behave more or less like 40 years of driving an ICE car has taught me to expect. That's a lot safer -- principle of least surprise, y'know.

There's a downhill mode that makes the car recover energy more aggressively, intended for when you're coming down a mountain. If the battery fills up before you get to the bottom, it will fire up the engine as a brake. I don't know how much (if any) fuel it uses for this -- the mpg meter stays pegged at "60+", which is its highest value.

Re:Brake Pedal (1)

lgw (121541) | about 7 months ago | (#46596781)

That's a great design on Ford's part. They really have gotten their act together on most things (if only they'd stop with the deliberately-cheap interiors, a holdover from Mercury and Lincoln still being different brands instead of different trim levels).

Re:Brake Pedal (0)

Anonymous Coward | about 7 months ago | (#46596645)

That's funny because I was just complaining of the opposite here...

I have always driven a manual transmission in my personal cars. I cannot stand it when I get in a rental car with an automatic transmission and its gas pedal behaves the way you prefer. It feels like a complete engineering disaster. Lacking braking on throttle lift is just as horrifying a feeling as lacking any road feel through an overly boosted power steering or land yacht suspension.

I fear the future where my personal car might have an automatic or other hybrid/electric drive-train, and the throttle would have this pathological behavior. It might be the day I permanently cease to enjoy driving.

Re:Brake Pedal (1)

Blakey Rat (99501) | about 7 months ago | (#46596657)

I don't know what model you drove, but my Fusion Hybrid does not behave that way. The only time it'll do regenerative braking without the brake pedal down is if its coasting downhill and would otherwise be gaining quite a bit of speed, and frankly in that situation I don't mind it applying a tiny bit of brake for me since I'd end up having to do it myself anyway.

mass in motion (4, Interesting)

RichMan (8097) | about 7 months ago | (#46595733)

The big factor is mass. To store energy you need to spin up and down the mass. However to drive in general you want to carry less mass on the vehicle.

Factor #1: A more massive flywheel can store more energy at slower spin rates.
Factor #2: A more massive flywheel is going to be more of a load in general driving.

The optimium point of flywheel mass is going to depend on driving conditions. Really you should have at least 2 interchangeable fly wheels that you physically replace in the vehicle. One flywheel for city driving one for highway driving.

Factor #3: A spinning flywheel is one hell of an energy store. Having a stopped vehichle with a fully spun up flywheel hit could release the spinning flywheel to the detriment of pedestrians in the neighborhood.
Factor #4: Starting from a stop and attempting to corner, left or right, having a spinning flywheel is going to do gyroscopic things to the vehicle.

There are all sorts of tradeoffs and safety considerations here.

1) & 2) solved by 60,000 RPM (3, Interesting)

raymorris (2726007) | about 7 months ago | (#46595815)

It would seem to me that at 60,000 RPM, the rotational momentum is so much higher than the linear momentum that 1) and 2) aren't really a problem.

3 and 4, on the other hand, could be a problem.

ps consider toy car "friction motors" (4, Insightful)

raymorris (2726007) | about 7 months ago | (#46595903)

It occurs to that this is basically a larger copy of the "friction motor" that was used in toy cars. The ones you'd spin up by rolling them on the floor , then you let go and they speed away. If you ever played with those, you know that the spinning flywheel has WAY more than enough rotational energy than required to accelerate its own mass. Those aren't going nearly 60,000 RPM either. (I think, I've never measured their flywheel speed.)

Re:mass in motion (2)

danlip (737336) | about 7 months ago | (#46595887)

If the flywheel spins parallel to the road I don't think it would affect turning left or right - except it would resist the car leaning to the side on a sharp turn, which might be a good thing.

Re:mass in motion (1)

Krishnoid (984597) | about 7 months ago | (#46596271)

... having a spinning flywheel is going to do gyroscopic things to the vehicle.

Isn't this usually addressed using counter-rotating flywheels? Or does that not apply to the issue here?

Re:mass in motion (1)

viperidaenz (2515578) | about 7 months ago | (#46595945)

Yeah, I'm not liking number 4 there.
If you you try to turn the flywheel around its vertical axis, it will try and twist around the horizontal axis, effectively trying to make the car roll over while it turns a corner.
The harder you brake coming in to a corner, the faster the flywheel spins, the slower you can take the corner.
It's also going to slow down the flywheel. That energy required to slow it down is going to come from the engine.

Re:mass in motion (1)

angel'o'sphere (80593) | about 7 months ago | (#46596775)

We have formular one cars that run with 400km/h ... using fly wheels.
I assume the engineering challange to scale that down to 200km/h is done.
Hint, the company we right now talk about is Volvo, that should ring a bell.

Re:mass in motion (0)

Anonymous Coward | about 7 months ago | (#46595959)

Meanwhile, having a stopped vehicle with a fully loaded gas tank hit could release massive amounts of fuel potentially leading to a fireball engulfing nearby pedestrians.

Re:mass in motion (1)

Immerman (2627577) | about 7 months ago | (#46596139)

Not much sense having a separate flywheel for highway driving - highway driving involves minimal braking, and so offers minimal opportunity to recover energy while doing so. Energy recovery systems are targetted specifically at stop-and-go driving at reasonable speeds, even "mobile parking lots" rarely involve high enough speeds to offer much kinetic energy for recovery - the vast majority of wasted energy is in idling the engine without using it.

Re:mass in motion (3, Insightful)

Matt_Bennett (79107) | about 7 months ago | (#46596233)

Counter-rotate the flywheels and #4 isn't an issue, no matter what the orientation is.

Re:mass in motion (1)

vivek7006 (585218) | about 7 months ago | (#46596277)

Car makers need to think outside the box. An average American car-driver is a fat-ass. Just figure out a way to convert all the potential energy stored in drivers fat ass/belly and convert it to kinetic energy, it will kill 2 birds with one stone

Re:mass in motion (1)

Lumpy (12016) | about 7 months ago | (#46596517)

Adipose.

Already have the answer.

Re:mass in motion (1)

kyrsjo (2420192) | about 7 months ago | (#46596337)

The mass of the flywheel is 13 pounds (~6 kg), while the whole device weighs 130 pounds (~60 kg). A lot of that is going to be shielding in case the rotor grenades.

Re:mass in motion (1)

DerekLyons (302214) | about 7 months ago | (#46596413)

Factor #3: A spinning flywheel is one hell of an energy store. Having a stopped vehichle with a fully spun up flywheel hit could release the spinning flywheel to the detriment of pedestrians in the neighborhood.
Factor #4: Starting from a stop and attempting to corner, left or right, having a spinning flywheel is going to do gyroscopic things to the vehicle.

You do know that cars already have a flywheel in them...

at 1/20th the speed, squared (1)

raymorris (2726007) | about 7 months ago | (#46596751)

This flywheel is spinning at 60,000 RPM.
Energy = mass * velocity^2 if I remember correctly, so this flywheel has a like million times as much energy and therefore potential danger.

Engineers please feel free to correct me, or actually do the math.

Re:mass in motion (1)

Lumpy (12016) | about 7 months ago | (#46596507)

The problem is the "engineers" are trying to break laws of physics. the extra mass of the flywheel will soak up all the power gained from spinning it up.
A flywheel is Power Output = Power input - losses, You will not have any gains from the flywheel only losses. it will conserve some energy, but not as much as an electrical regeneration system does.

Re:mass in motion (2)

mspohr (589790) | about 7 months ago | (#46596769)

"There are all sorts of tradeoffs and safety considerations here."
Thank you for your insightful comments. I am sure that the Volvo engineers haven't considered any of this and will be very grateful for your valuable input.
This is why /. is such a valuable resource for engineers the world over.

Safety issues? (1)

Hentai (165906) | about 7 months ago | (#46595821)

So what happens when the flywheel shatters at high speed?

Re:Safety issues? (1)

jakedata (585566) | about 7 months ago | (#46595929)

No shatter. It's spun carbon fiber. You end up with a big bowl of carbon spaghetti.

Re:Safety issues? (1)

viperidaenz (2515578) | about 7 months ago | (#46595955)

Same thing that happens when you spin a CD at 60,000rpm in a CDROM drive. It shatters into a million pieces and destroys anything delicate inside the drive.
You'll be fine if you're not in the car when it happens.

Re:Safety issues? (0)

Anonymous Coward | about 7 months ago | (#46596003)

You cease to have brakes?

Re:Safety issues? (1)

H0p313ss (811249) | about 7 months ago | (#46596033)

Two thoughts:

1) How fast do your wheels spin now?
2) How often do they shatter?

Re:Safety issues? (1)

drinkypoo (153816) | about 7 months ago | (#46596227)

1) How fast do your wheels spin now?

Not very fast at all. Most engines turn less than 7,000 RPM and the wheels turn notably slower. The overdrive gear ratio will be just over 1, and the highest rear end ratios in common use are around 2.7:1. There's nothing whatsoever in most production cars which spins as fast as KERS.

Re:Safety issues? (0)

Anonymous Coward | about 7 months ago | (#46596383)

> There's nothing whatsoever in most production cars which spins as fast as KERS.

Not entirely correct. Turbo-charged cars are quite common and the turbine in them spins extremely fast. The KO3 in my chipped VW GTI spins around 160,000 RPM. Stock is still over 100k RPM.

Re:Safety issues? (1)

HornWumpus (783565) | about 7 months ago | (#46596405)

Turbo impeller.

Re:Safety issues? (1)

Lumpy (12016) | about 7 months ago | (#46596555)

At 70 miles per hour a tire with a rim 15 inches wide will spin about 129 times per minute.

Call me when you invent a car that the wheels spin at 60,000 rpm, I want to watch you drive it.

Re:Safety issues? (1)

Matheus (586080) | about 7 months ago | (#46596219)

thousands of babies across the globe suddenly die in their sleep...

Waiting since the '90's (1)

fortfive (1582005) | about 7 months ago | (#46595859)

. . .for this to be in a production car. Back then, I read an article in Discover (?) Magazine about Mercedes working on this technology. Then nothing until today. Sounds great, to me.

Also a really interesting tech I read about at that time was smaller motors at the wheels. No need for transmissions and shafts and gears.

Pie in the sky tech I heard about then, too, was instead of brush and coil motors, having charged plate motors.

Still nothing on those last two.

Re:Waiting since the '90's (1)

H0p313ss (811249) | about 7 months ago | (#46595975)

My father's been involved in alternative energy research since the 70's, I'm pretty sure I heard about regenerative braking with flywheels in the early 80s. (This is what happens when you're related to mad scientists whose idea of fun involves steam engines, solar panels and ocean thermal energy, preferably at the same time...)

Here's a patent filed in 81 and granted in 85 [google.ca] .

This stuff is like clothing fashions, just wait long enough and they'll all come back, hopefully with the patents expired.

Re:Waiting since the '90's (1)

steveg (55825) | about 7 months ago | (#46596733)

When I was in school (mid 70s) there was work being done on "super-flywheels," both for automotive use and for fixed energy storage. Flywheels can deliver (or accept) virtually unlimited power -- not unlimited energy, but if you need a burst of power in a very short time, your limitation is not going to be the flywheel.

One of the applications I read about then was for a university particle accelerator. The local city got upset at having the lights dim all over the city when they fired it up, so they spent hours spinning up a flywheel to release it in milliseconds.

This is handy for vehicles, since batteries can't accept or deliver power as rapidly as flywheels can and that limits both braking and acceleration. On the other hand, in an accident, being able to release power rapidly is more dangerous.

Super-flywheels, incidentally, were made of fiber based materials spinning at very high speeds, just like described here. They had the same or higher energy density as metal flywheels but failed less catastrophically. Metal flywheels tend to chunk when they fail, the fiber materials to shred.

Re:Waiting since the '90's (1)

Bomarc (306716) | about 7 months ago | (#46596063)

The 90's ???? This concept was proposed in the back in August 1970 in Popular Science. [popsci.com] article "Super Flywheel to power Zero Emission Car" [popsci.com] .

I also remember a same concept article talking about buses (mass transit) when I went to school (don't remember the magazine though).

Re:Waiting since the '90's (1)

drinkypoo (153816) | about 7 months ago | (#46596261)

Also a really interesting tech I read about at that time was smaller motors at the wheels. No need for transmissions and shafts and gears.

Motors at the wheels are actually pretty lame, because they increase unsprung mass which negatively impacts handling. A motor for each wheel is a nice way to go, though. Modern CV shafts rarely fail until the boots do. Go inspect your CV shaft boots and have them replaced if they appear to be leaking.

Re:Waiting since the '90's (1)

viperidaenz (2515578) | about 7 months ago | (#46596279)

Brush and coil motors are old tech now. It's transistor and coil now

Probably Williams F1 Tech. (3, Informative)

Virtucon (127420) | about 7 months ago | (#46595861)

Williams F1 has been working on this technology for quite awhile now. It's definitely fascinating. This video shows [williamsf1.com] the technology applications.

Re:Probably Williams F1 Tech. (0)

Anonymous Coward | about 7 months ago | (#46595983)

iirc Audi is supposed to use this type of energy storage in their prototype Le Mans 24h cars, so it's hardly a new thing.

Re:Probably Williams F1 Tech. (0)

Anonymous Coward | about 7 months ago | (#46596251)

Yes, supplied by Williams:

http://www.williamsf1.com/Advanced-Engineering/Williams-Hybrid-Power/Media/News/Williams-Flywheel-Technology-Proves-its-Robustness-by-Helping-to-Power-Audi-to-Le-Mans-Triumph/

Totally different working principle (0)

Anonymous Coward | about 7 months ago | (#46596299)

That one uses electric motors. The Volvo one doesn't.

Re:Probably Williams F1 Tech. (1)

Anonymous Coward | about 7 months ago | (#46596377)

Porsche has also been working on it, using the stored energy to accelerate out of corners.

Done over 50 years ago (2)

Animats (122034) | about 7 months ago | (#46596013)

This isn't a new idea. It's been tried several times since 1950 for city buses, which are constantly stopping and starting. In 2009, one was developed for use in London. In the 2009 model, the linkage to the flywheel is mechanical, through a continously variable transmission [torotrak.com] , not electrical. Although this has been in test for several years now, it's only one bus.

That's the same technology Volvo is using. Putting this in a car seems marginal. It makes more sense for buses and delivery vans.

Re:Done over 50 years ago (1)

WindBourne (631190) | about 7 months ago | (#46596521)

It really does not make sense for buses/vans. Far better to move those to electric.

Fix the broken interface, keeps changing on me (0)

Anonymous Coward | about 7 months ago | (#46596025)

This sucks, every so often I come to Slashdot, and the interface has changed from black text on white, to gray text on gray. It just sucks. Fix this crap please.

My Tesla does that too (0)

Anonymous Coward | about 7 months ago | (#46596041)

They call it regen. It uses components the car already has, adds no weight and no cost.

electric machines (1)

SpaceManFlip (2720507) | about 7 months ago | (#46596043)

this concept has been used for awhile in UPS (battery backup) systems with a giant heavy flywheel on a generator-type spindle, which is kept spinning by electric motor power until the power goes off and then the rotating energy is put out into a generator to output AC power to critical electronics

Wasted Brake Energy? (-1, Flamebait)

fustakrakich (1673220) | about 7 months ago | (#46596045)

How many of you would still be alive if our cars didn't have brakes? I don't consider avoiding an accident a waste. Airbags are expensive you know.

I'd prefer air power (1, Interesting)

Ken_g6 (775014) | about 7 months ago | (#46596049)

This air-hybrid system [popsci.com] uses nitrogen, hydraulic fluid, a hydraulic motor, and a couple of high-pressure tanks. I imagine it shouldn't cost much more than this flywheel, and it should store energy much longer.

Re:I'd prefer air power (2)

coolsnowmen (695297) | about 7 months ago | (#46596151)

It is also more explosive.

Re:I'd prefer air power (3, Interesting)

amorsen (7485) | about 7 months ago | (#46596713)

Compressing gas has a fairly lousy energy return. The air heats up when being compressed, and that heat is wasted unless you insulate the tank.

I love the complexity (2)

WindBourne (631190) | about 7 months ago | (#46596103)

Seriously, rather than focusing on a much cheaper saner approach of a simple electric car, these car makers continue to make more and more complex systems, which will have maintenance issues down the road.
This is why tesla, and I think Nissan, will become major players in the car making business.

Kinda like an old tractor (not) (3, Interesting)

tomhath (637240) | about 7 months ago | (#46596125)

Early tractors had the power take-off geared directly to the final drive. So if you were using a big rotating implement like a mower which was driven by the PTO you needed to be very careful when you got to the end of the field because the mower had so much energy you had no chance of stopping the tractor with the brakes.

To get over that they added a coupler that would let the machine freewheel. I've been on a tractor without that coupler and it's pretty scary. Not stop and go, just go and keep going.

Re:Kinda like an old tractor (not) (1)

Anonymous Coward | about 7 months ago | (#46596339)

When I was growing up this was a frequent occurrence on old 8N Ford tractors. When I was in high school I bought my own ratcheting coupler because my family was too cheap to buy me one.

Re:Kinda like an old tractor (not) (1)

HornWumpus (783565) | about 7 months ago | (#46596611)

Offtopic I know.

I'm still looking for something nice to say about Ford sense they sold their tractor division. Anybody?

Funny gyrations... (1)

Ancient_Hacker (751168) | about 7 months ago | (#46596345)

So what happens if you come to a stop and then want to turn right? You have a flywheel spinning real good and you're trying to change its axis. Either it's going to twist and bust its bearings and do considerable mayhem, or your car is going to go around the turn on two wheels. Fun times!

Prototype? (1)

BigFire (13822) | about 7 months ago | (#46596609)

My 2005 Prius already have this technology as does many other hybrid vehicle.

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