Half a croissant, on a plate, with a sign in front of it saying '50c'
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flywheel in-wheel hub engine

flywheel inside vehicle wheel controlled by magnetic clutching
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(+1, -4)
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The following text uses the word Car but should be read as any motorized vehicle regardless of number of wheels or size. Bicycles, trains, trucks and helicopters apply equally.

The engine:
This is a standalone engine inside a wheel working with no connections to the vehicle's external parts. The consists of batteries, a brushless electric motor, two flywheels and a magnetic "clutch" system.

The electric motor is set between the two flywheels - one serving as the electric motor stator, the other as the rotor.

Magnetic clutching:
There is a magnetic clutch between the left flywheel and the left side of the car wheel, and another magnetic clutch between the right flywheel and the right side of the car wheel.

The magnetic clutching works
- either by electromagnets which cause pull and attachment between the flywheel and car wheel when powered,
-or with permanent magnets, which cause pull and attachment between the wheel and flywheel, when the car wheel's magnets are physically pulled closer or further from the flywheel.

When starting, both clutches are free of the car wheel. The flywheels begin turning in opposite directions because of the motor.

Gradually powering the left clutch, which connects the left flywheel #1 to the car-wheel, causes all the power to pass to the other free flywheel (#2). Meanwhile, the wheel stays stationary because of friction or a light press on the breaks.

Now we have only the right flywheel (#2) moving in the forward direction (say clockwise). With the motor giving it power.

(The same affect can be achieved if the left flywheel is clutched in advance, and then the motor will simply be pushing the right flywheel)

Forward movement:
Once the right flywheel is at high speed, by partially clutching the right flywheel #2 (the only one currently moving) to the right of the car wheel, power is gradually passed to the car wheel which moves forward. The left flywheel is still clutched tightly to the left part of the wheel and the electric motor continues to add power to the flywheel.

If this doesn't work (expecting the annos to explain why) the motor could be powered down in effect causing the two flywheels to be detached, the left one turning slowly at the wheel's speed while the right flywheel moving rapidly, and slowly transferring its power to the car wheel. This process could be repeated in pulses.

When the right flywheel slows down and reaches a threshold (say only 100 times the speed of the wheel) the left clutch is released, and the electric motor winds the right flywheel up to speed again.

Regenerative braking and self acceleration:
(1) When the accelerator switch is not being pressed or (2) when downhill and wheel is accelerating more than the power being put in, and (3) in particular when the brakes are pressed, the left clutch is released, in effect causing the right flywheel to slow down, to a speed close to the speed of wheel itself, while the left flywheel reverses direction and begins accelerating in the opposite direction.

Once reaching a certain threshold (say 50 times the wheel speed) the left flywheel clutch is activated, which gradually slows down the wheel movement.

Retaining power
Once the wheel reaches threshold speed, both flywheels are released and the energy is added back into the two flywheels, by the electric motor.

Once reaching a safety margin of speed the motor is stopped.

pashute, Oct 17 2012

bike hub with two motors
shameless self promotion [xaviergisz, Oct 18 2012]


       I guess I'll be the first to say it this time: how do you plan to overcome the flywheels' inertia to allow for effective steering?
Alterother, Oct 17 2012

       The whole powertrain is going to be unsprung mass. That's going to do nothing for the ride quality of the vehicle and make axle and suspension design problematic.   

       Heavy wheels (in proportion to the overall mass of a vehicle) are bad things and designers strive to avoid them.
8th of 7, Oct 17 2012

       Put the wheels on the top, then.
MaxwellBuchanan, Oct 17 2012

       I think it's a good idea, but how much energy will the clutches consume compared to energy saved by this idea? And increasing un-sprung weight not a good idea for ride quality. Unless this a forklift your talking about. I don't bun nor bone here
evilpenguin, Oct 17 2012

       For slow-moving vehicles that have long stationary periods but must be ready to roll when needed (such as forklifts), this would be implementable, but I don't know as the expense and maintenance requirements of such a complex design would be offset by the efficiency gain.
Alterother, Oct 17 2012

       // how much energy will the clutches consume // More than 99% of the energy will be consumed in the clutches as described. That peak efficiency of 1% will only be achieved when the flywheel has slowed to 100x the wheel speed. When it is spinning faster, the efficiency will be much lower than 1%.   

       That's why cars have transmissions rather than a single gear and a heavy-duty clutch that slips continuously at speeds less than 50mph.   

       Here's a (hopefully) simple explanation. I'm going to state this in terms of linear motion as well as (rotational). The principle is the same, but is possible easier to visualize linearly. The force (torque) decelerating the flywheel is the same as the force (torque) accelerating the wheel since the brake (clutch) applies force equally and opposite on the wheel and flywheel. Energy is force times distance (torque x angle). Since the flywheel travels 100 times as far as the wheel and the force is the same, the energy lost by the flywheel is 100 times the energy gained by the wheel.   

       This could be improved by using a generator instead of a clutch (like using regenerative braking rather than normal brakes in a linear situation) so some of that energy could be recaptured as electricity instead of heat in he clutch.   

       Of course this whole system could be simplified to be a single motor/generator between the wheel and the flywheel to get similar performance. All of the ways that you are using the two flywheels and clutches rather than a single motor and flywheel appear to come from misunderstanding conservation of angular momentum. That also prevents continuous travel. I'll get into that later if I get a round toit. The one advantage of using clutches rather than (or in addition to) a generator is that for the same size/weight you might be able to get a larger surge of acceleration with a clutch, but with the huge inefficiency, I suspect that overheating problems would reverse that advantage in almost all cases.
scad mientist, Oct 18 2012

       I'm assuming by magnetic clutching the author is talking about electromagnetic clutches that are normally open, or allow the pto shaft to rotate when not powered. If the clutch requires electricity (energy) how much electricity would be required to close the clutches and how would that compare to the power "saved" by this ideas setup? There didn't seam to be any sort of pressure plate or spring included in the authors idea, so there clutches would require electricity to close.
evilpenguin, Oct 18 2012

       //press on the breaks// Yikes!   

       //The same affect// Aaahhhhgh!   

       Maybe the cause of Joseph of Arimathea's exclamation was not a Black Beast, but his scribe making a similar ghastly error.   

       I'm afraid I can't offer any useful comment on the device since I'm a bit lost in all that description. If it's as simple as I think, I'd be surprised if the fifth - or third - paragraph was reached before running out of stuff to say, so I'll have to re-read in the morning when my brain will be able to cope with more than just pedantry.
TomP, Oct 18 2012


       Well, we can do you pedantry and ideas without the analysis, and we can do you pedantry and analysis without the ideas, and we can do you all three concurrent or consecutive. But we can't give you ideas and analysis without the pedantry. Pedantry is compulsory. They're all pedantry, you see.   

8th of 7, Oct 18 2012

       Please youtube 'magnetic clutch' for a mechanical one, and wikipedia for electromagnetic clutch.   

       The energy needed in both cases is minute. And the weight as well.   

       Please notice that matchbox cars work very well with flywheels.   

       Please notice that for the speeds we are talking about an extremely lightweight flywheel can be constructed, controlled with safety margins as described, never exceeding a certain speed.   

       About steering: Sorry, that was lost in my many edits before I got the idea up in the air.   

       When the two flywheels are counter turning they allow change of angle. The move of energy from one flywheel to both, should be with very little loss, because of the magnetic extremely low-friction nature of the "bearings" between most parts of this system.
pashute, Oct 21 2012

       //        Please notice that matchbox cars work very well with flywheels.    //   

       Please notice that matchbox cars are not real cars and are not expected to be steerable.
Alterother, Oct 21 2012

       // an extremely lightweight flywheel can be constructed //   

       Conservation of angular momentum …   

       The lighter you make a flywheel, the faster it has to spin to store the same amount of energy. The faster it spins, the greater the energy loss due to air friction (unless it's enclosed in a vacuum chamber) and in the bearings; and the air frictional losses are square-law.   

       Big, slow flywheels are therefore better.
8th of 7, Oct 21 2012


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