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Electric Flywheel Hybrid Hybrid
Using a motorgen as the axial (magnetic) clutch for the flywheel, which itself consists of the emg's stator and regen capacitor/battery, allows the vehicle to use a gear transmission. The system is lighter than either an exclusive emg or flywheel regen system. | |
We'll start with an hybrid vehicle where an EMG(electric motor/generator) sits between the engine and the transmission, its rotor mechanically clutched at each end. A supercapacitor (or battery) used to store regenerative energy is also housed in the EMG casing as part of the "stator" assembly. Now
to segue smoothly into the Idea...
The basic post premise is to use the EMG, not only for what it does best but also as a flywheel ¹, to assist in regeneration ² , for the purpose of system weight reduction, ie: since a large portion of the energy is being handled by the flywheeling motion, the EMG system doesn't have as much to do and can be smaller and lighter, reducing overall cost and weight.
The first thing that needs to be done is redesign the EMG as a flywheel. The rotor is part of the driveshaft as usual: this doesn't change. The stator assembly, normally fixed to the casing (that's why they call it a "stator"), can be unclutched and allowed to turn: this is what creates the flywheel effect. The regeneration-capacitor is also part of the flywheel to add useful weight and eliminate the need for motor brushes in the stator while its moving.
The second thing is to add a couple extra-low gears to the transmission. These are used to spin the EMG flywheel up/down at far past normal engine speeds to increase (exponentially) the amount of energy that can be stored.
At which point it should be mentioned that a CVT could be used instead, but they aren't as robust.
The third thing (which has nothing to do with regeneration) is to note that, when the stator is locked to the casing, the electric motor can be used for primary propulsion or engine assistance at any time, powered by a battery pack.
So at the end of the day we've a hybrid braking regeneration system which is both lighter and cheaper than systems that exclusively use either electric-regeneration or flywheel-regeneration.
² - props to [Vernon]'s
TwinFlywheel
storing energy in two places: catalyst [FlyingToaster, Apr 25 2012]
I am sure I saw one of these on a bicycle...
http://www.launchpn...lectric-propulsion/
... but I am stumped for the link. [4whom, Apr 25 2012]
interesting
http://www.scienced...i/S0304885309003850
[4whom, Apr 26 2012]
interesting-er
http://www.motoredb...wthread.php?t=23955
[4whom, Apr 26 2012]
Skytran
http://www.skytran.us
Skytran will be running on a flat Hallbach effect rail called Inductrack (see Wikipedia). Used to be on their website. Halbach himself got cancer from the magnets and ended up trying things on himself for the sake of science. His eerie emails still prevail on the web. [pashute, Oct 15 2012]
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Annotation:
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Could your idea be boiled down to the following? |
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//Mount an electric generator / stator between
the engine and transmission of a vehicle, in the
form of a heavy flywheel, to capture the engine's
otherwise wasted rotational energy at idling
speeds or slightly above. To do this, the flywheel
would need a 2- or 3-speed torque converter and
throwout gear to engage a planetary ring gear and
clutch assembly, to drive a CVT gearbox. |
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Using engine braking rather than wheel-mounted
brake disks would allow the flywheel to scavenge
much of the braking energy required before small
wheel brakes complete the braking procedure.// |
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Not sure if that's the thrust (sorry about that one)
of your idea? |
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More like: given a normal (non-hybrid, non-regenerative) engine/transmission design: |
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Toss out the old (engine)flywheel. Stick a motorgen in instead. Decouple the stator from the casing and use the stator as a regen-flywheel. Put a couple extra-low gears in the tranny specifically so the new flywheel can be spun up faster than the engine usually runs. Attach the regen-capacitor (which stores only enough energy to account for normal regen braking) to the stator for even more flywheel mass. |
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You've now got a start/stop design which does braking regeneration. The regen energy that doesn't go into/from the flywheeling goes into/from the electrical regen-cap. |
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If it was *just* a flywheel-regen system it'd have to be heavier. If it was *just* electrical-regen it'd have to be heavier. |
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//[beanangel] usually co-opts some medical paper and extrapolates the theory therein, whilst making it less comprehensible to English speakers.//
Same thing I guess, but in this case it's mostly my own ideas that have been built on, summarized in the first paragraph. |
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Gotcha. Much more concise. Thank you. [+] |
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okay, I put most of the beanification into the summary and rejigged the first paragraph. |
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re your // //'s which sorta require a link to get the context, it looks like the specific differences that make this idea unique are: |
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- the rotor isn't the flywheel. The rotor(driveshaft) is the field-coil part of the electric motor which is of a lighter weight. The stator containing the windings, and the attached regen-capacitor, are the flywheel. It's done this way because weight on the driveshaft is a drag on acceleration/deceleration. |
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- no planetary gear. I don't completely understand how they work anyways even if there was a need. For clarification, most of the time the stator actually earns its name: clutched immobile to the casing, making the whole thing a bog-standard electrical motor. The act of clutching, obviously, takes place when the stator has been brought to a stop. I prefer a field-coil over permanent magnets to allow for better control. |
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- no CVT is necessary. The electrical regen sops up any energy that the flywheel doesn't catch so there's no need to tailor the RPM's exactly. |
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- no 2-3 speed torque converter. The extra low gear(s) in the transmission handle the overspeed bit, and torque conversion is handled in the rotor/stator magnetic interface with any slippage being stored electrically. Though none of that is schematically necessary in your version either since there's a CVT. |
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A properly designed electric motor/generator doesn't need attached gearing, for getting power into it or out of it. Because there are electric motor designs in which the RPM is related to the frequency of the applied alternating current. And other ways, I think. Based on various annos I've seen in other HB Ideas, [neelandan] may know more about the available options. |
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Rotating stator means brushes for the electrics... is that going to be a problem? |
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Sorry, not a quote from anywhere. Simply a
consolidation of my understanding of the idea, as I
would write it, based on what you wrote. |
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[UB] I thought you had found a draft of one of your deleted ideas and decided to match it up (and if so I was wondering what the post-date would be). The major difference appears to be that this one uses the electrics' electrics for regeneration and for torque-conversion, as well as using the weight of the electrics as a flywheel. |
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In fact the torque conversion is worth a doubletake. When it's storing energy, the energy goes to the flywheel and slippage to the regen-cap. While it's returning energy to the wheels, the energy is coming from the flywheel, *but* slippage is *still* being loaded into the regen-cap. So the sequence there would be: unload flywheel (while partially energizing cap), lock flywheel, unload capacitor. |
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[mitxela] well... yes and no... mostly no. |
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The stator is on the flywheel and so's the regen capacitor. The connections there are fixed, no brushes. So for regeneration, there's no loss. |
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When it's just being used as an electric motor utilizing a battery pack mounted somewhere else on the vehicle, the stator is going to be clamped to the casing immobile. The battery-pack connects to leads on the casing; the leads are sprung, touching corresponding conductive stripes on the stator. The leads are retracted a bit when the stator is unclamped for flywheeling. Again, no brushes. |
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The only places there would be brushes is on the field-coil on the rotor, but FC's don't use much energy to begin with so total brush loss would be almost nothing (or you could go totally brushless by using permanent magnets). |
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[Vernon] just to clarify, this one doesn't include //attached gearing//. The extra low gears in the transmission are there solely for the purpose of increasing the flywheeling RPM range to be far in excess of engine RPM range. |
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However, the gears do provide a system electrical purpose: they keep the driveshaft rpm close to the flywheel rpm. The closer the match the less regurgitated slippage (see 2nd para this anno). |
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Because of the view I'm using, I misread the title as "Electric Flywheel Hybrid Hybrid Flying Toaster" which sounds like a fun idea. |
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Thought I was headed down the path of transborgification did you ? not completely. It's still a fun idea... okay maybe you have to stretch the definition of "fun" a bit to include "a mildly intriguing mental exercise", but still... |
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I have seen something similar on a bicycle. You could pedal and gear into the motor (see link), for a flywheel effect. Regenerative breaking also fed into it. If need be you could feed in electricity and derive power from it. Just can't find the link. It was a DARPA project IIRC, or Japanese. It was a good few years ago, in mitigation of my stupidity. |
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^Great motor (your link)... jaw-dropping power to weight ratio, but the speed ? What needs 8400 RPM ? |
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Starter motors for small gas turbines, for one. |
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One of the links mention that if you add more poles you can decrease the operating speed. Funny thing is, it's so lightweight that cooling is a problem at lower speeds. |
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[Vernon] okay I recounted my thumbs, and the flywheel could be put after the transmission. That would be smoother in many respects but it'd mean giving up the Swiss army-knife thing where the electric motor also functions as alternator, starter and genset. |
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[edit: no, wait... the transmission is needed to pump up the rotational speed to the point where it's useful as a flywheel] |
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// What needs 8400 RPM // |
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High-speed machine tools. Anything designed to generate
ridiculous amounts of horsepower but not much torque.
Prototype NASCAR engines. DC-electric jet engines
(although I think those are still on the drawing board). High
volume hydraulic pumps. My 7" angle grinder. To name a
few. |
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Other things being equal, power increases with rotational speed, so a small, compact, powerful motor will inherently be a fast one. |
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Dremel tools run at up to 40,000 revs. |
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[pashute] wow, that's some fancy h'bing: I didn't even realize there'd be a problem and there's a possible solution. |
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At some time the idea (or a draft or something) contained an explanation to the effect of ... |
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There's 3 structural elements to the flymotor:
• - the emg rotor which is on the driveshaft(clutched at both ends) between engine and transmission, which acts in a normal rotory fashion; it's inside of
o - the combination emg stator and regen battery, which constitutes the flywheel, which is inside of and clutched to
O - the casing of the flymotor which is bolted to the engine and transmission casings. |
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During regular driving... |
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the • , being part of the driveshaft, is turning, while the o is stationary, clutched to the O (which never turns). At this time, if external batteries are available, the electric motor, which consists of the o and the •, can be run to add to the driveline power. (ie: bog standard electric motor assist) |
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Regen and launch aren't symetrical. |
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During regenerative braking, |
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the • is declutched from the engine (as per usual hybrid operation, to keep engine-braking from wasting energy; the engine is then turned off). |
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However what makes this unique is that the o is declutched from the O. Now that the emg is in generator mode, the difference in rotational angular velocity between the • and the o produces electricity (which is stored in the supercap in the o), *but also* the heavy o will start to spin, eventually catching up to the •'s speed. At this point (well, probably a bit before actually), the driver downshifts. The lightweight • spins faster and again the velocity difference provides electrical regen and again the flywheel is spun up faster as it's dragged along. Rinse and repeat through a couple extra-low gears, finally the generator is de-energized (turned off) when the o velocity equals the • velocity in the lowest gear, and the vehicle is finally stopped with mechanical wheelbrakes (as per usual). |
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things get a bit weird. From low gear, the generator (yep _generator_ function) is again energized. Now the flywheel o is pulling the • into rotation, using the generator function as a clutch. This generates more electricity which is stored in the supercap. When the o finally slows down to near the speed of the • it's time to upshift, rinse and repeat. Eventually the o stops rotating completely. Before it starts spinning backwards, it's clutched to the O. Power is now flowing through the motor and the regen-cap now powers the electric motor. At any time during launch the (ICE) engine can be started and engaged as well. |
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You don't get more _power_ into or out of the flywheel/motorgen combination than you do using just the motorgen, but the flywheel storage means the supercap can be smaller (and flywheel storage is more efficient) |
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Yeah the launch is a bit non-intuitive. Mostly 'cuz the motorgen is a component in two different systems: |
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i) a generator acting as a slippy clutch for the flywheel during both regen and launch cycles, and
ii) a motor during launch (after the flywheel's spent), and as part of the regular driving cycle (in the normal hybrid manner with external batteries)
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Note how the motor waits until after the flywheel is finished with its launch sequence before starting its own. |
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</muttering>
(there's something about stopping the flywheel that I haven't actually nailed to the floor completely quite yet: in order to squeeze most of the last few drops of energy out of the flywheel, the very last gear you put it in before stopping the flywheel has to be pretty high for the speed, meaning the • rpm is pretty low: probably too low for the engine to be comfortable in. Reason to do that is that as soon as the o and the • match speeds, the generator starts working as a motor and wastes a bit of energy stopping the flywheel.)
</m> |
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On the surface at least it looks translatable to bicycle usage, but in order to work the same as on a car there would have to be a clutch between gears and pedal-chain, and the flywheel would be on the out-side of the gears, not on the wheel. Perhaps something in a coaster-bike setup. |
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Both supercaps and batteries are lossy, for different reasons. Modern batteries have really good in/out efficiency and energy storage capabilities, but capacitors have phenomenal power-handling and longevity attributes. |
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I haven't tripped over the efficiency ratings of supercaps (with regulating circuitry) yet. |
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