is it possible for a spring powered automobile?

[cameron marical]

i think there could be. i dont think there would be much mileage, or much room, but i think it could work. just have alot of springs, and the kind that are in wind up toys, just alot longer and bigger. it could rewind as it drives and as it sits still outside, just have like a windmill-like thing that rewinds the spring on top of or on the car some where. what do you guys think? has it beem tried?

[Mr Skeptic]

No, springs don't have such a good energy/weight ratio. However, I have heard of a giant flywheel being considered.

[cameron marical]

whats a giant flywheel? {please excuse if this is a stupid question}

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Merged post follows:

Consecutive posts merged

.oh, by the way, i like your avatar.

[CaptainPanic]

A flywheel is a large (heavy) wheel that is used to store energy. The energy is stored in the form of kinetic energy... the flywheel is spinning fast. When the energy is needed, it is transferred: the wheel slows down, and whatever application needs energy speeds up.

 

Read more here (at exactly the place where you would expect the information to be ).

 

A car could use a spring to store the energy too... but I'm not sure you would reach the end of the street... It's just not possible to put so much energy in a spring.

[ydoaPs]

Rewound by driving? I'm fairly certain that wouldn't work.

[timo]

Rewound by driving? I'm fairly certain that wouldn't work.

By breaking, i.e. transferring the (linear) kinetic energy of the car to rotational (kinetic) energy of the flywheel.

 

Q: What is the difference between a nuclear engineer and a car engineer?

A: The nuclear engineer tries to make sure that nothing can go wrong. The guy building cars knows that something will go wrong, anyways. As far as I know (from being told by my professor for experimental physics several years ago), the main reason not to use that kind of energy storage is not the problem of getting the system to work but that in case of a car accident you do not want to have heavy, fast-rotating iron wheels flying around. I don't think I'd want springs jumping around, either.

Edited February 25, 2009 by timo
added "not" (and tricked the edit-timeinterval :P).

[Mr Skeptic]

I've heard graphite flywheels can fail safely, and are also very efficient. I can't imagine safe springs though, not with enough energy to power a car.

[insane_alien]

I've heard graphite flywheels can fail safely, and are also very efficient. I can't imagine safe springs though, not with enough energy to power a car.

 

well relatively safely, what you end up with is a kevlar bag full of hot graphite powder.

[Xittenn]

Last time I checked the goal was to make a superconducter based flywheel that could spin really, really fast(like 30000m/s +) as opposed to making one that was fast but heavy! The major problem with this scenario being the superconductor flywheel falls apart...........................I'd say breaks like a DVD but it's most definitely an unravelling.

[cameron marical]

could a flywheel power a car? i still dont really understand this thing. is it just like something spinning constantly and when energy is needed it is just transfered by a chain or something along those lines? what gets it spinning? could you use that little windmill thing idea to get it spinning and speed it up and use that to help out the enrgy?

[Mr Skeptic]

You could certainly recharge a car using a windmill. However, if you carry the windmill with you, it would use up a lot of room in the car, or cause a lot of drag when moving. Solar would be far more compact, and can be made aerodynamic.

[CaptainPanic]

could a flywheel power a car? i still dont really understand this thing. is it just like something spinning constantly and when energy is needed it is just transfered by a chain or something along those lines? what gets it spinning? could you use that little windmill thing idea to get it spinning and speed it up and use that to help out the enrgy?

 

Situation 1:

The car is going at constant velocity and the flywheel is not moving. There is of course a normal engine that powers the car.

 

Situation 2:

The car approaches a traffic light, and needs to slow down. The kinetic energy of the car is transferred to the flywheel. The car slows down, but the flywheel gets all the kinetic energy and starts to spin faster and faster as the car slows down.

 

Situation 3:

The traffic light turns green. The flywheel will transfer all its kinetic energy back to the car. So, the acceleration of the car did not cost any energy.

 

 

The flywheel can help the car be more efficient. You still need an additional source of power (an engine). How the energy is actually transferred is probably the same mechanism as any gearbox? I'd appreciate some comments on this part because I don't know for sure! But I can imagine that an engine can also go fast or slow, while the acceleration is being controlled with the gas pedal, clutch and gears. This flywheel just goes slower and slower as you accelerate, so you'd have to choose the gears differently, but I don't see why it would be really different.

[npts2020]

CaptainPanic; That is basically how every flywheel assisted drive train i have ever seen works.

The biggest problem with a flywheel is, that the heavier they are the better they are for the task, unfortunately you then have to carry all that weight around.

As to the original question, any spring that could provide enough power to run an automobile would have to be fairly massive to enable even short trips before rewinding (think how big a watch spring is compared to the watch). Even if you could work out safety and durability issues it seems to me that doing this would never be any more than an interesting academic exercise.

Edited February 26, 2009 by npts2020

[Sisyphus]

A spinning mass with kinetic energy comparable to a speeding car is always going to have safety issues. If something jams it (like, say, a distorting impact), all of a sudden all of the angular momentum is going to transfer to the body of the car...

 

You would also definitely have some funny gyroscopic stuff going on. But hey, maybe that could even be put to good use in terms of stability? (That would still mean another big system which must not fail.)

 

And finally: weight. How much would a flywheel needed to store that kind of energy weigh? Either a whole lot (making the much car heavier and therefore less efficient), or less, but moving crazy fast.

 

That said, it does look not only workable, but actually surprisingly promising. For simplicity and rapid "charge/discharge," apparently batteries just can't compete with a big spinning ball of metal. Neat.

 

Oh, also:

 

http://en.wikipedia.org/wiki/Gyrobus

[Xittenn]

note the date............................

 

http://www.time.com/time/magazine/article/0,9171,943707,00.html

 

http://en.wikipedia.org/wiki/Flywheel_energy_storage

 

I like this one 'cause it's about HTS bearings being modeled....................

 

http://arxiv.org/ftp/cond-mat/papers/0510/0510346.pdf

Edited February 27, 2009 by buttacup

[cameron marical]

oh, ok. so a flywheel is just an energy saver thing, like a brake that instead of wastes the energy as heat and friction, is transfered as kinetic, reusable enregy for the car. a big ball of spinning metal indeed.cool. do many, or any, cars have these? what does?

[CaptainPanic]

CaptainPanic; That is basically how every flywheel assisted drive train i have ever seen works.

The biggest problem with a flywheel is, that the heavier they are the better they are for the task, unfortunately you then have to carry all that weight around.

As to the original question, any spring that could provide enough power to run an automobile would have to be fairly massive to enable even short trips before rewinding (think how big a watch spring is compared to the watch). Even if you could work out safety and durability issues it seems to me that doing this would never be any more than an interesting academic exercise.

 

I know and I agree. I was just explaining the concept in simple wording, because some people might not understand what we're talking about.

 

Step 1: explain concept.

Step 2: explain problems challenges.

 

2. Challenges

As npts and others wrote, there are already a lot of good reasons (mentioned in this thread) not to use the flywheel in a car.

In practice a flywheel will only be worth its weight in any type of traffic that slows down and speeds up a lot. The weight of the flywheel should be low, and it's maximum velocity high, so that you don't carry around a lot of extra weight, but you're still able to store a significant portion of the vehicle's kinetic energy... but you will carry around extra weight.

 

That gyroscope issue could be a challenge, but I don't think so... cars only make (sharp) corners in one plane (on the flat surface of the earth), so if the axis of the flywheel is completely vertical, you won't notice any effect. There are of course exceptions to this, which must be taken into account (some funky mountain roads perhaps).

 

In a crash, I think we could have a challenge problem. The flywheel really contains a lot of kinetic energy (the same as the moving car), so that has the potential to do a lot of damage if it goes out of control. We all know how much damage a speeding car do... and the flywheel will have the same energy (only it spins, and does not have any linear motion - does that make it any safer?).

 

In short: car manufacturers consider safety first, and efficiency second... and I don't think we'll be seeing flywheels in cars soon.

 

oh, ok. so a flywheel is just an energy saver thing, like a brake that instead of wastes the energy as heat and friction, is transfered as kinetic, reusable enregy for the car. a big ball of spinning metal indeed.cool. do many, or any, cars have these? what does?

 

Flywheels are used, but not so much in cars... and not at all in normal road cars. I'm no mechanical engineer, and I am not able to explain it any better than wikipedia.

[npts2020]

oh, ok. so a flywheel is just an energy saver thing, like a brake that instead of wastes the energy as heat and friction, is transfered as kinetic, reusable enregy for the car. a big ball of spinning metal indeed.cool. do many, or any, cars have these? what does?

 

buttacup's middle reference pretty much covers the transportation uses. From the looks of it nothing has ever been put into production, which is in agreement with what little I have seen written about the subject.

[cameron marical]

what about having alot of springs. im not talking about one big one. i mean the cars like almost full of them and its just one after the other after the other. ya, once you run out that would suck, but you could just have a mixture of solar panels and mini-windmills to crank them back up. and you can even have it rewind as the other ones are going.

[npts2020]

what about having alot of springs. im not talking about one big one. i mean the cars like almost full of them and its just one after the other after the other. ya, once you run out that would suck, but you could just have a mixture of solar panels and mini-windmills to crank them back up. and you can even have it rewind as the other ones are going.

 

I would be the last one to tell you that such a thing is impossible. The problem is that springs are more suited to applying steady smaller force over a longer time than applying the sudden large force from stopping and starting that is required for operation of vehicles large enough to carry people or freight. I will have to think about it for a while but I don't believe many small springs would have any energy advantage over a single large spring.

[syadnom]

There are a few issue with using a flywheel. 1, the flywheel is a a gyro and will resist changes to its angular movement. This requires that the whole flywheel be mounted in a 3 axis gimbal setup so that the flywheel is allowed to float within the gimbals so the car would be allowed to change the plane of momentum, for instant changing from flat road to a hill or a banking turn.

 

Because of that, the charging and recovery system cannot be mechanical as that would interfear with the gimbals. so now you must use a generator/alternator mounted inside the gimbal and much get the electricity out through the gimbal structure. This is fine except that the gimbals must be mounted so that the positive pole and the negative pole are isolated. You would also need seperate electric drive motors.

 

As far as flywheel breakdown, you should just overengineer the flywheel material. That will increase costs but consider how dangerous gasoline is and you can make a good case that the flywheel is much safer.

 

oversimplified efficiency would be (mass of the flywheel * speed of rotation / mass of the car * desired speed) * efficiency of alternator and wheel motors.

 

with modern magnetic bearings and high strength materials this would be a small engineering feet. someone just needs to have the money to invest and access to high tech materials and capable manufacturing facilities.

 

i suppose this is really just a mechanical battery with electric power transfer.

[CaptainPanic]

There is a reason why one of the few applications that actually run on a spring is a clock (wristwatch, and other clocks). The electric versions of those run for 4 years on a tiny battery. In other words: they use almost no energy at all (much less than 1 watt)... and the spring is adequate for the job.

[Norman Albers]

I read last summer that in Europe somewhere there is a prototype flywheel bus. I guess we mount it vertically, no?¿?

[Gadget Man 55]

No, springs don't have such a good energy/weight ratio. However, I have heard of a giant flywheel being considered.

 

 

How about if you had a couple of very big coil springs like in a watch, mounted under the floorboard of the vehicle on top of each other. The springs could be wound by a small diesel engine. When starting off the day the diesel engine would make certain both springs were wound to the maximum capacity which would happen when you shut the vehicle off. When starting off on a trip the next day the vehicle would be powered by one spring until the spring reached a predetermined state of being unwound. Say, for example 75%. When that happened the vehicle would start running off the other, fully wound spring and the diesel engine would wind the other spring to its full 100% capacity switching back and forth as the springs became unwound. I do see a problem though that would have to be overcome. When slowing down or stopping or even traveling at a steady speed there would have to be some control over the springs so that the full power of the spring could be reduced or increased depending on the driving conditions. Some type of a mechanical rheostat. Also the springs would have to be made so that they had a long life without breaking. The floorboard of the vehicle would have to be made very strong just in case a spring would break for safety reasons. Naturally the cost to make the springs could not be cost prohibitive. The diesel engine would have to be small enough to to the job without using too much fuel or what would be the point of using springs to power the vehicle.

[PaulS1950]

You are adding losses in your diesel/spring engine. It takes more power to wind the spring than you can get out of it so you add the 30% efficiency of the diesel to the 70% efficiency of the spring and you get around 21% efficiency from the system. You would do better to use the diesel alone.

 

Paul