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RE: regenrative Wheel hubs need thoughts

  1. Mar 13, 2013 #1
    Hello,

    I am working on a regenerative wheel hub design for an EV. This is not a regenerative braking system, nor is it a violation of the conservation of energy idea.

    The idea encompasses using the rotating mass of a wheel to provide a trickle return charge to the battery pack as a wheel is rotating while driving.

    Problems:

    Placing the magnets too close to the stator produces a magnetic pulse resistance (drag).

    Placing them too far away, leads to no magnetic impulse to the pick up coil(s) (no benefit)

    The idea is to modify a hub, and mount the molybdenum permanent magnets in it.
    Then mount the stator to the part of the hub that doesn't move.

    With a little trial and error adjust the gaps of the stator to rotor interface to cause the least amount of magnetic resistance. Yet close enough to still cause an electric pulse in the coils, while not adding significant drag to the driven wheel should cause a charging circuit.

    Having this mounted in the center of the wheel will reduce mechanical drag due to mechanical advantage.

    In theory, this should provide a minimal source of drag on the wheel, and provide a source of trickle charging energy to the electrical system.

    The idea is to capitalize on the moving parts, and potentially wasted potential energy sources. Over the entire charge duration of the battery pack this should add an extended range, even if it is a small increase.

    The stator, produces 12volts and unknown amperage. When attached to an engine it will supply all the energy for all needed lighting plus battery charging, in its OEM application. So it should be sufficient to use for a charging circuit. In an overdrive scenario the wheels actually spin faster than the crankshaft of a ICE. So freeway speed (60-70MPH) should generate some pretty good charging rates. Nothing compared to the expenditure. But Im after extending range, not running the car on it. Regenerative braking claims horrible returns of 15% or so. The idea of charging whenever moving is potentially useful.

    So please correct me if Im wrong, but if this system were attached to each wheel should it not help to extend range? I do understand that if improperly set up it would hinder range.

    Even a 10%(thinking big here) increase over the range of the battery charge could be significant.

    What would be the minimum needed charge rate to cause any effect. Use generals.

    Thoughts?
     
    Last edited: Mar 13, 2013
  2. jcsd
  3. Mar 13, 2013 #2

    russ_watters

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    No, it can only hurt the range. Conservation of energy demands that any electrical energy produced be exactly balanced by the mechanical energy extracted from the car's motion. Add in efficiency losses, and you have a net loss in range.
     
  4. Mar 13, 2013 #3
    Then how do you explain two volts generated by attaching a drive cpu fan to a second cpu fan via a common drive shaft on the rotor? Just did the test.

    This is not an equaling effect. only a scavenging effect.

    If attached to a circuit capable of storing up and discharging it to the battery it could potentially slowly charge the battery. Again in theory.
     
  5. Mar 13, 2013 #4

    davenn

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    the original fan motor will be working harder as its now driving another motor
    as a result it will most likely be drawing more current fom the power supply
    AND it will be drawing more current from the supply than what is being generated by the second fan motor

    You DONT get anything for nothing ... the extra power has to come from somewhere

    Dave
     
  6. Mar 13, 2013 #5

    davenn

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    look at this with another practical vehicle example....

    The compressor for the Air Con. unit in your car ( assuming your car has A/C)
    Its usually turned by the fanbelt or other belt thats also driving the alternator
    When the A/C is off the A/C motor shaft is just freewheeling and not producing any significan drag on the system.
    Have you noticed how your engine rev's drop when the A/C is turned on ? drops by several 100 RPM, thats cuz there is now an extra load on the engine.
    So to get the engine back up to producing the same amount of power to the wheels,
    you have to increase the fuel to the engine ( ie ... step on the gas peddle a little harder)

    Doing your system as stated in your first post is going to have the same effect and will effectively reduce the amount of power available to the wheels, by the same amount as being taken by the generators you install, therefore you are going to have to increase your fuel supply to the engine to make up for it

    Dave
     
  7. Mar 13, 2013 #6
    true I understand that.

    But when this is attached to a 400 to 4000 lbs vehicle. The losses will be minimal. Remember its being setup to have a very small impact and offer a trickle charging effect. This is not meant to sustain the vehicle. The drain at the wheel hubs will be negligible to unnoticed.
    The wheel acts like a flywheel on a car. It stores energy. I think your thinking of much more drag than on the wheel than i am.

    Im just curious of what the minimum charge rate would be needed to show any effect to the range. Presume a 100 mile range off of a full charge.
     
    Last edited: Mar 13, 2013
  8. Mar 13, 2013 #7

    Ok good now think of the AC clutch disengaged like you mentioned. Its still spinning that shaft. Is that noticed? No. When the clutch is driving the compressor, yes it is.
    This design will be little if any drag on the wheel hubs. Like the freewheeling shaft
     
  9. Mar 13, 2013 #8

    davenn

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    you will notice it as a higher fuel useage its going to cost you directly in the pocket

    but if you dont care about using extra fuel .....


    Dave

    PS maybe its total electric ??
     
    Last edited: Mar 13, 2013
  10. Mar 13, 2013 #9

    davenn

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    the less drag, the less power you will generate therefore the more useless/pointless it would be !!

    what is the battery of the vehicle ? 12V, 24V, 48V .... something else ?

    a 12V battery will need ~ 13 - 14 volts and probably at least 1A ( 13 - 14Watts)
    to produce any signif charging effect
    and respectively higher voltages for the other 2 battery examples
    You are not going to generate that sort of power without there being a signif. drag on the wheels.
    BUt to generae that 13-14W you will expend maybe 15 - 20W generating it
    so as Russ pointed out you will still have an overall loss situation

    Dave
     
  11. Mar 13, 2013 #10
    yes it is 12 volt typically. But could be a lithium-ion pack as well.

    i was playing with using motorcycle engine magnetos, and turning the wheel hub into a Rotor. with the stator being mounted in the non-moving portion of the hub assy.

    Its pretty straight forward really. Given that the generator is located at the center of a fairly heavy wheel, and with the dynamic forces applied to the vehicle moving it should produce quite a bit of power.

    Taking a motorcycle engine apart, down to just the flywheel (with magneto under it) and crank shaft the shaft spin freely with pulsing yet still produces energy.

    My two CPU fan rig is running perfectly fine (blades removed) and producing a constant regenerative energy. Though it is low partially due to the fact it a motor, not a generator. and due to its small size. But its producing none the less. Is the motor running slower than it would normally? Im sure it is, but its not really noticeable. And i dont have a laser tachometer to measure it as it sits and runs.

    I do have an electric scooter (cheap chinese one) that I can test the concept on. But like you said it may come down to either it making it worse, or no effect at all. It should be fun to play with at the very least.
     
    Last edited: Mar 14, 2013
  12. Mar 14, 2013 #11

    davenn

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    size of the wheel is irrelevent
    whatever its size it requires a proportional amount of energy( power) to rotate it
    and ANY energy you take from that wheel to turn some other generator is going to require MORE energy from your power source. and because nothing is 100% efficient,
    there are always losses, you WILL input more additional energy into the system that what you can take out with your generator

    its a loose - loose situation
    To coin an old phrase ..... There's no such thing as a free lunch

    Dave
     
  13. Mar 14, 2013 #12
    Heh,

    Yeah I know.
    The wheel will not be moving any parts. Its overall weight increase would be in grams.
    The magnetic drag would be the only potential drag losses.
     
  14. Mar 14, 2013 #13

    davenn

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    that drag is not really any different to moving the generator shaft directly
    IT IS STILL drag!! :) its still a power /energy loss in the system that has to be made up by supplying more power to the wheel to get it to maintain is non-drag rev's

    Dave
     
  15. Mar 14, 2013 #14
    Jut seems an enormous waste to have so much kinetic energy in a wheel and not exploit it in some way.

    For instance, in most ICE the exhaust flow is wasted as heat and flow. It is never tapped for energy unless it is used to compress incoming air into the intake. Why not attach a generator to the thing rather than a compressor (provided the generator could manage the RPM's)? Seems like a huge charging potential there. Never heard of it being done.
    Seems like the whole idea of a hybrid car is just starting out, with so many possible means of energy reclamation on a vehicle that are not being used.

    ID like to find a way to make this bastard of a law work for us, rather than be a constant wall against us as engineers and designers. Im working on my graduate degree now, and my idea wallet is much larger than my actual wallet(unfortunately).

    Just seems like adding a mini alternator to each wheel shouldn't have any more effect than in a standard application. In fact it might potentially cause an efficiency gain, even if small. Every little bit helps toward better efficiency. Such as leaving the electrical drive motor in constant motion whether powered or not. When on, it acts as a drive motor. When off it act like a generator.

    My idea for the charging circuit was to use a capacitor driver (if thats the right term). Where like a relay (controls big amperage with a small input) the small energy charge created would be stored up, and then dumped back into the battery. Thus creating a higher charge rate even though it would be a pulsed charge, supplied from a lower input source.
     
    Last edited: Mar 14, 2013
  16. Mar 14, 2013 #15

    russ_watters

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    Indeed, but there is no value of "minimal that could turn a loss into a gain.

    Even if you assume you could achieve perfection - zero loss - then the net effect of your system will be exactly zero impact on range:

    Ein-loss=Out
    So if the loss is 0:
    Ein=Eout

    Your statement about it being like "freewheeling" implies you don't believe conservation of energy applies here: you thing the "magnetic drag" can be less than the power produced. It can't.
     
    Last edited: Mar 14, 2013
  17. Mar 14, 2013 #16

    berkeman

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    And this thread is now closed. We don't discuss over-unity nonsense here.
     
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