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Author Topic: Could car wheels be modified to act as generators?  (Read 48980 times)

Offline LeeE

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Could car wheels be modified to act as generators?
« Reply #25 on: 13/02/2009 19:49:09 »
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The motor would be extremely light compared with an 'engine' and it would be right at the fulcrum

I think you're comparing dissimilar things here; you should be comparing similar electric motors mounted in different ways, not comparing dissimilar power plants, which make the comparison pretty meaningless.  When you do that you find that having both the motor and the drive shafts moving increases the mass of the moving parts when compared with not moving the power plant.  Why have the motor moving about when there's no need for it? you need a UJ of some sort at each end of the drive shaft anyway, whether it's placed between the chassis and the motor, or between the motor and the drive shaft, so why complicate it and increase the loads it has to bear unnecessarily, even if it by a relatively small amount when compared with a heavier power plant?  Like I said, if you compare similar power plants, all you're achieving by having the power plant move is increasing the mass of the moving parts, which increases the requirements, makes things more complicated, not less, and more expensive, not cheaper.

Regarding just reaching in through the engine compartment to access inboard brakes: it might just be possible to do in my old mini, which doesn't have a large engine and lots of ancillaries filling the engine compartment, but even so, it would still be a tight squeeze to get two hands down there.  For my other car, it would simply be impossible.  Not only is the bonnet deeper but it's full of engine and all the other ancillaries; even just getting to a couple of the spark-plugs needs you get in to a particular contorted pose, in addition to using a UJ on the plug wrench.  Incidentally, how would you deal with the rear brakes (assuming a front-engined car)?

And yes, with regenerative braking you might need to change the pads less frequently,  but that assumes that the manufacturers don't downgrade the spec of the brake pads to suite the lowered braking requirements, and you can be sure that they will as it will reduce their costs.

Re the car in that demo: being able to raise and lower the ride height can be useful in vehicles that have to go off-road, but tilting it is a bad idea because not only is it likely to be disorientating and induce motion sickness but it also reduces your visibility on the side that's lifting; as you tilt over you'll not be able to see the road on that side - dumb idea.  The only benefit I can see in it is to reduce shear forces in your neck at very high cornering speeds and if you're corning that quickly on a public road you're a danger to other road users.  Funnily enough, F-1 cars use active suspension specifically to keep the car flat through cornering, as tilting the body would upset the aerodynamics.
 

lyner

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Could car wheels be modified to act as generators?
« Reply #26 on: 13/02/2009 22:35:07 »
Changing inboard pads in conventional cars may be made hard because of the engine. There wouldn't be one in the new system.
You do not seem to take point that " unsprung mass"  is not increased directly by the motor mass. A gimbal motor mount just has to cope with a non rotating, low stress load, as opposed to a UJ. The whole motor - brake unit could be lifted out by hand- slid off the drive shaft even.
There may be several reasons for rejecting the basic idea but I don't think your objections are as significant as you say.
We do share the reservations about the revolutionary ideas.
 

lyner

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Could car wheels be modified to act as generators?
« Reply #27 on: 13/02/2009 22:43:44 »
.....and why do you insist that a UJ is needed each end of the drive shaft?
 

Offline LeeE

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Could car wheels be modified to act as generators?
« Reply #28 on: 14/02/2009 20:54:13 »
.....and why do you insist that a UJ is needed each end of the drive shaft?

Because you won't be able to entirely eliminate all forward and backward movement of the wheels relative to the motor, so you'll need to accommodate movement from the motor to the hubs in two axis.  Without doing this you'll end up with fatigue problems, either in the driveshaft, or in the motor bearings/mountings.

Even if the motor is fixed to the chassis and rotates as you suggest, it'll still impart a degree of torque on the hubs/wheels, which will have the effect of increasing the unsprung weight.  Yes; with a very light weight motor this might be small, but it's still an unnecessary overhead.

I still can't see any benefit in having the engine/motor moving around when it's just the wheels that you want to move; the energy to move the motor has got to come from somewhere i.e. the power plant, which just reduces the energy available for propulsion and complicates the motor mounting, and which now has got to be capable of handling not only the power of the motor but also allow the motor to move as well.
 

lyner

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Could car wheels be modified to act as generators?
« Reply #29 on: 14/02/2009 23:37:29 »
Using a spline joint will take out any stretch needed in the shaft. Even with UJs you would still need this if the geometry were not exact. What force do you think will produce 'fatigue'?
The motor will not 'rotate - it will just tilt/ oscillate and, yes there is a contribution to unsprung mass but how much torque is needed to  tilt the motor by perhaps 10degrees+/- at the rate of wheel bounce? The Moment of Inertia is proportional to the square of the distance from the fulcrum and the relative MI of the wheel will be enormous compared with that of the motor (Which would only have much the same mass, actually)
The engine mounts would have very small load on them - they do not 'rotate' like a big-end bearing but 'rock' like a small end bearing and you must well know the difference in size and wear between those two on an engine of any given power.  There is far more stress imposed on a UJ, because of its necessary small size. In fact, by removing one UJ and replacing it with a length of (tubular) shaft - you have reduced the total rotating mass.
You are not using the word 'power' correctly in your last para; the only 'power' involved would refer to 'rate of work done' . The only work done on moving the engine about comes from the movement of the road wheels up and down on the suspension and the contribution from the load of the engine is, as above, very small. Again, I don't think you have actually identified a source of 'energy loss' here - what force and what distance are involved?
 

Offline LeeE

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Could car wheels be modified to act as generators?
« Reply #30 on: 14/02/2009 23:49:13 »
The issue isn't about needing the drive shafts to stretch but that there will a degree of forward and backward movement in the wheels relative to the motor producing a shear force if there's not a two-axis bearing between both ends of the drive-shaft.  And yes, I used 'power' incorrectly there.

Other than that, I surrender. :-X
 

lyner

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Could car wheels be modified to act as generators?
« Reply #31 on: 15/02/2009 10:13:53 »
A two axis mounting on the motor will achieve exactly the same effect of stress relief. How can it not? It will allow the wheels to be in any position within its limits and still be 'pointing at them'. The mountings will not allow the motor to rotate, of course.
 

Offline teragram

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Could car wheels be modified to act as generators?
« Reply #32 on: 25/02/2009 19:00:44 »
If anybody is still looking:-

The Michelin movie demonstrates what can be done, not necessarily what will be done, in the future. Re the banking of the car, only a nutcase would want to drive a car which behaved in that fashion (although they do it with trains?). The movie demonstrates the control that can be engineered into systems using electrical and programmable technology. The system shown could I think easily cope with keeping the car exactly parallel to the road surface under all cornering conditions.
A couple of points worth repeating from the (very poor) soundtrack are:-
There are no mechanical brakes,
Deceleration can reach 1g.
(I do not suggest that we have cars without brakes (reducing unsprung mass), but the system does make mechanical brakes redundant, apart from parking brakes.)
The accompanying movie with soundtrack in French, seems to claim that the motor power is  30Kw, (it’s only as big as a tin of beans!!!).

The comments about added unsprung mass are very relevant, but try
http://www.telegraph.co.uk/motoring/environment/2748517/English-electric-Lightning.html
Please read it all, and note for interest’s sake the comments on Nano Titanate batteries (relevant to the general discussion on electric cars).
 

Offline jujusalvador

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Could car wheels be modified to act as generators?
« Reply #33 on: 11/03/2009 16:50:14 »
"If you generate energy by taking it out of the wheels' rotation it'll just mean that the engine has to work harder to keep the wheels rotating at the same rate"

That happens if you have generators that use kinetic force, that kind causes friction, but you can have a device that dont have resistance between the coils(static disc) and the magnets(rotative wheel), and using that type, this can be real possible... because the force applyed by the motor in the transmission will be the same of having a custom wheel, or a custom wheel with magnets side by side with a static disc generator!

i been trying to develop this kind of technology since october/08, and allready patent it here in Portugal, soon will put here some information about...

good work sophie centaur, how do you resolve the problem of the suspension? in your schematic you dont mention it.

sorry my english, :P king regards

If you generate energy by taking it out of the wheels' rotation it'll just mean that the engine has to work harder to keep the wheels rotating at the same rate.  Also, as you're introducing another stage in the power chain, which will not be 100% efficient, you'll end up with s slightly less efficient system overall.  As the others have said, it's only real benefit would lie as a braking system where some of the energy used to brake the car can be recovered instead of being wasted as heat.
« Last Edit: 11/03/2009 16:52:56 by jujusalvador »
 

lyner

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Could car wheels be modified to act as generators?
« Reply #34 on: 12/03/2009 10:37:04 »
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That happens if you have generators that use kinetic force, that kind causes friction, but you can have a device that dont have resistance between the coils(static disc) and the magnets(rotative wheel), and using that type, this can be real possible..
Do you not understand that you need to do WORK on a generator in order to produce Power from it? Even if you were to eliminate the friction, you would still have to provide power equivalent to the product of the V and I from the generator.
 

Offline jujusalvador

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Could car wheels be modified to act as generators?
« Reply #35 on: 13/03/2009 17:33:05 »
V and I? sorry dont understand what you mean.

yes u'r right, you have to do work on a generator to produce power from it, but imagine an electric car with battery's, the car can almost use an alternate source like "solar or magnetic generator", so the batterys will never stay without charge to start the car again.

If the car is stopped the wheels are not generating, but also the motor is not consuming. But, imagine if case the 4 wheels generators was so efficient, that the regenerative system can produce more energy at movement that the one that is being applyed on the motor, you will allways have a small reserve of battery charge, to start the car again after you stop it.

this can be helped by small wind turbines at the front of the car, maybe in the spot of the radiator(cooler), because when you move your are constantly passing by air that can rotate wind generators at high speeds.

The question is, how much energy can we get from 4 friction less wheel size generators at 20km/h (example), and how much energy a standard electric motor consumes from the batterys at the same speed. At more velocity more energy is being consumed, but more energy is being generated to.

The system will work like the Electric Hybrid, that can constantly recharge the batterys with a fuel generator, and feed the electric motor at the same time, or like the standard fuel motor cars, that can constantly charge the battery with the alternator, and feed the electric system (lights, panels, cooler, etc) in simultaneus.

the system, will be a standard electric car, one light motor connected to the transmission.

Do you think that maybe it can be done?

Maybe this will have interest,

newbielink:http://www.greenoptimistic.com/2009/03/05/thane-heins-back-emf-recovery-free-energy/ [nonactive]

"His device can accelerate a motor from 100 rpm to 3,500 rpm without increasing power. Every electric motor has a force that opposes the propelling electromagnetic field inside it, called “Back EMF”. Heins succeeded to recover this back-EMF and, instead of letting it cause resistance, he transformed it into useful power."




Do you not understand that you need to do WORK on a generator in order to produce Power from it? Even if you were to eliminate the friction, you would still have to provide power equivalent to the product of the V and I from the generator.
« Last Edit: 13/03/2009 17:38:11 by jujusalvador »
 

lyner

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Could car wheels be modified to act as generators?
« Reply #36 on: 13/03/2009 20:23:12 »
Electrical power = V(volts) times I(current)
That must be supplied from somewhere. You don't get it for free.
However you get it. Wind generators will need to be pushed through the air by the motor - and don't say you're moving anyway  because the motor will have to be pushing harder to provide the IxV again.

Any external input will be useful  but solar cells are pretty low power, providing a few tens of Watts unless they are a Huge Area, as on a satellite. Best bet is to carry lots of charge in batteries. The latest design may give an advantage.
Regenerative braking could return some of the Kinetic Energy of your moving car back into the battery. The hybrid system is a good one because the energy from the fuel doesn't have to be lost when you slow down and you can operate your engine at maximum efficiency. It ain't magic, though.

I'm afraid the last thing about 'back emf' is not right - or you didn't read it right. Back emf doesn't actually constitute a loss of energy.
 

Offline jujusalvador

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Could car wheels be modified to act as generators?
« Reply #37 on: 14/03/2009 22:42:39 »
i was talking about new gen wind generators, the wind come from the front and goes out to the back of the car, without causing resistance, that will be the same, you only will be regenerating the air energy, the force of air against te car will be equal, with or without wind generators.

Electrical power = V(volts) times I(current)
That must be supplied from somewhere. You don't get it for free.
However you get it. Wind generators will need to be pushed through the air by the motor - and don't say you're moving anyway  because the motor will have to be pushing harder to provide the IxV again.

the wheel generators without friction will work like the hybrid system, even if they cannot be overunit and regenerate all the energy that the motor use, it will give u much more efficiency and drive distances.

dont understand u, you dont think it can be done?


Any external input will be useful  but solar cells are pretty low power, providing a few tens of Watts unless they are a Huge Area, as on a satellite. Best bet is to carry lots of charge in batteries. The latest design may give an advantage.
Regenerative braking could return some of the Kinetic Energy of your moving car back into the battery. The hybrid system is a good one because the energy from the fuel doesn't have to be lost when you slow down and you can operate your engine at maximum efficiency. It ain't magic, though.

i have just copied the text from the green optimistic site, i dont invented nothing, and i dont say that the back EMF constitute a loss o energy, simply is a force the opposes the propelling electromagnetic.

I'm afraid the last thing about 'back emf' is not right - or you didn't read it right. Back emf doesn't actually constitute a loss of energy.
 

lyner

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Could car wheels be modified to act as generators?
« Reply #38 on: 14/03/2009 23:42:01 »
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dont understand u, you dont think it can be done?
I KNOW it can't be done because your idea that, somehow, the turbine can be made to turn without consuming any power (from some source) is not viable. If your turbine is turning your generator which is generating electrical power then there HAS to be a source of power. This power must come from the car engine, in this case. That is the most basic law of all Physics. For a turbine to turn, there has to be some air turbulence - an efficient body shape reduces drag as much as possible byt promoting laminar flow as much as possible.
The same thing applies to 'wheel generators'.

Either the green optimistic site is in cloud cuckoo land or you have misread it, somewhere.

You can't eliminate friction and you can't get energy out of a system that you haven't put into it. Any machine will be a net consumer of energy.
« Last Edit: 14/03/2009 23:44:49 by sophiecentaur »
 

Offline rex789

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Could car wheels be modified to act as generators?
« Reply #39 on: 18/03/2009 17:48:53 »
light or not you will just be taking the energy u already produced for one reason and use it for another. this would most probably leave ur initial reason for producing that energy at a very big loss. also taking energy away from brakes will lead to their not working as effecients. car makers go out of their way to add extra energy into their braking sytems (eg bmw, heating the brake pads before the brakes are to be applied). you must produce heat in order to stop a car. if you make a system that somehow takes that heat away then there must be some performance that is decreased. producing a system that is more effecient in getting energy out of the fuel is the only salvation for mother Earth.
 

lyner

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Could car wheels be modified to act as generators?
« Reply #40 on: 18/03/2009 23:25:27 »
light or not you will just be taking the energy u already produced for one reason and use it for another. this would most probably leave ur initial reason for producing that energy at a very big loss. also taking energy away from brakes will lead to their not working as effecients. car makers go out of their way to add extra energy into their braking sytems (eg bmw, heating the brake pads before the brakes are to be applied). you must produce heat in order to stop a car. if you make a system that somehow takes that heat away then there must be some performance that is decreased. producing a system that is more effecient in getting energy out of the fuel is the only salvation for mother Earth.
That is rather mixed up. You do not 'need' heat  to dissipate KE; the process of simple friction braking just transforms the KE into thermal energy  (cause and effect  are the reverse of your statement). BMW use a practical solution for increasing friction,I guess - it's not fundamental.
The acceleration and braking cycle, will not be efficient, of course, but regen braking can help.
 

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Could car wheels be modified to act as generators?
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