Diesel electric, hub motor, the way forward?

[greg123]

Hi guys,

Not been on here a while but my friend looking at a BMW C1 got me thinking again.

I'd love a diesel, I'd love a scooter, I'd love an enclosed.

Mainly I wouldn't like a fixed timing generator engine trying (!!!) to accelerate a bike using variable speed ranges when it only runs good at one rpm. I also woultn' like the compramised at best gearbox/driveline (though the cvt option seems reasonable).

I think the following setup would address virtually all disadvantages:

1) static speed di engine, very efficient
2) rare earth magnet generator on the above engine, eff >95%
3) highly efficient (>95%) hub motor, no gears needed
4) and here is the kick - a power capacitor bank, charged during braking and if required also charged by spare capacity from the engine when idling/cruising at less than top speed

Most of the energy from braking is recovered, meaning most of the acceleration is 'free' and drastically improved town mpg.

Another benifit is that acceleration can be HUGE, if needed. This system can easily put down say 100hp for a short (20sec) acceleration period on what is otherwise a 25hp system. Which is great, as 20/30 hp can can even move a car at highway speeds, it's acceleration and hills that need a short term 'kick'. A mini with this system and hub motors did 0-60 in about 5 seconds or something.

Another benifit is you have engine and flywheel generator (compact) and you place it where you like. In the wheel you have a hub motor. Add a small capacitor bank (half the size of a car battery should do it) and you have a whole system.

You could seriously double fuel economy (combined regenerative braking, running the engine efficiently and low driveline losses/gearing losses) of a typical 20hp diesel bike, AND have the HP of a 1000cc bike for 0-60 sprints when you want it, or overtaking. Okay you can't keep it up all day, but the power of the engine alone would mean you could sit at 80 I guess. In any case, unless on a race track full throttle/serious acceleration is only every short bursts, so road use would suit this system. For economy misers the capacitor bank would only be charged by wasted energy when braking (no brakes needed, these hub motors can fully brake and convert to electricity) and for the speed freaks, when the capacitors are not fully charged by braking any spare enegine capacity (when not driving at full throttle) is diverted to the capacitor bank, building up a big reserve for the next acceleration. When bank is full, the engine keeps it's revs but throttles down to only provide the torque needed to provide the current for that moments cruising. If no torque is needed, engine can drop to idle - all other times sits at efficiency peak.

This system could fit into a scooter or other layout and be more flexible for builds. Can fully rubber mount the engine too, as doesn't have to be rigid to support a drivetrain link.

Thoughts anyone?

Greg.

[sbrumby]

Just a few thoughts, 20hp quite heavy lump, generater rare earth whatever that is, also quite heavy, wheel motor quite heavy I imagine, also what size are these various bits, also the bank of capacitors very expensive, and correct me if I am wrong but you would still need a battery? as capacitors loose power overnight. So I dont know what the all up wieght would be but I bet you would struggle to do 80mph.

[greg123]

Weight does not make any difference to top speed on a flat anyhow. Aerodynamic drag (Cx) and rolling resistance do.

The wheel motor and generator would weigh considerably less than a typical gearbox & drivetrain.

Read about rare earth magnets (Neodymium, light) here http://en.wikipedia.org/wiki/Rare-earth_magnet and this is an example of an electric bike using a neo motor http://tuikip.wordpress.com/2007/06/06/ ... motorcyle/

And no, other than a starter battery, you wouldn't need batteries. The idea isn't to use a huge heavy bank of capacitors to run the thing, purly to capture the energy from braking or store extra energy for acceleration. If you imagine the kind of heater you would need running off a battery to heat your brake pads and disk up to nearly glowing red, it's a hefty amount of electric can be recovered from a 70-0 stop. As it is, we waste hundreds of kettle's worth of watts into braking heat and pour fuel in the engine to accelerate!

Greg.

[Sphere]

The UK road authority will approve a home-cooked breaking system like that? I'm pretty sure you'd have a hard time getting it through in Holland.

[greg123]

The Chinese EV scooters go through SVA with it no problem.

Of course you can add a 'home cooked' disk brake system you nicked off another bike as well, nothing to stop you, and have both - with regen braking providing the braking normally.

[Sphere]

Right. But they are massproduced. So I suppose you would want to encorporate an existing module. Also, for insurance reasons, I wouldn't alter the breaking system after approval.

[oilburner]

The concept sounds great, but I don't think it would work very well in practice. Basically, you are talking about diesel electric drive not unlike that used on locomotives with a bank of capacitors to store reserve energy for acceleration.

To sustain 60 mph on flat ground, no wind, you would need at at the very least a 7Kw Permanent alternator which would weigh about 80 lbs driven by a 15 hp diesel engine which will weigh well over 100 lbs. You also need an electronic control system - complex in this case to handle switching of the capacitor bank. I suspect the capacitors would be very expensive, heavy, and bulky to withstand the high current involved. The bike would require a very robust wheel motor to withstand the 100 hp you project - lots of unsprung weight which would deteriorate ride and handling. The cost to build this bike would be prohibitive.

Member's experience suggests you can sustain 60 mph with reserve for a headwind with 12hp for a fraction of the cost and complexity.

IMHO if this was a practical solution, it would be on the market today, and I'd probably own one.

Avery

[lex]

Hi Folks,
It's easy to be negative about Greg's idea, but you have to remember what the world at large thinks about the idea of a diesel bike of any variety!!!!!

Capacitors storing brake energy is the electrical equivelent of a large flywheel but without the disadvantages of all that spinning mass!!!


I have often thought of 'enhancing' a motorbike by using hub electric motors in each wheel to charge the main battery. They would work from the throttle - ie activated as generators when the throttle is shut off (simple switch acting against the throttle barrell) Normal brakes would be un altered and used to add to the stopping power EXACTLY the same way that engine breaking works now. You could even set it up to prevent skidding as a kind of anti lock brake system. I think you could reduce the size of the generator /alternator on such a bike using such a system (and free up scarce horsepower!) - you could even run some of the output through the rear brake light so that when using the systems drivers behind are warned of your reducing speed!!!
Keep thinking freely!


Lex

[greg123]

Thanks for your support Lex! I agree, it's good to keep thinking big, at least as a wannabe designer, an example of what happens when you stand still would be the great british bike industry in the 60's.

Avery, your comments are interesting. Though a diesel bike is GREAT and I love the little 15hp that you pointed to, the idea that 'if it could be done, it would be - stick to proven methods' doesnt' really apply. To be fair, what the public DONT want is a bike with 15hp that can only manage 60 and has a 4 speed gearbox with acceleration to match a trabant.... It's fun, but taking the philosophy further there would have been no need to develop heavy and complex disk brakes, abs and heavy control systems, bigger and more complex 6 speed boxes etc - if the old fashioned way was perfect.

If you have a look at the electric bike I linked in my post, you will see that a fully electric system isn't heavy or complex. Controlers are readily available, the capacitor bank is small as you are NOT talking the AH of a battery, merely the AH required to acceelerate to road speed which isn't much. There are several motorcycle conversions done DIY you can find on the net some of which do 70mph and accelerate VERY fast. This system would be similar, however taking out the heavy batteries for a heavy engine and then have a much greater range. All this HAS been done, you can buy electric super scooters with the technology (minus the diesel engine). I'm just thinking of combining what would be an obvious powerplant (single speed = efficient, di diesel engine).

Also you wouldn't use an alternator generator. We are not talking a heavy unit to bolt on - alternators are very inefficient - we are talking a unit using a 'flywheel' as the spinning componant and built round it. Realistically probably 2 inches out of the end of the engine would be enough, these rare earth magnets are VERY powerful so you can keep them small and having a magnet field rather than an electromagnet field (alternator) makes them efficient - it's the exact same technology used in all good wind turbines where the generator is compact, relatively light and doesn't generally require gears (too much friction losses) and is very efficient to capture the little wind power.

Food for thought anyhow, it's all proven tech, I'm just suggesting a packaging.

Maybe I should get a ready made decent electric scooter and try to fit a diesel engine generator in and take the batteries out.

Greg.

[greg123]

Here is a fairly modern Scooter coming on to the market, some of the technology is a bit out of step though. It's probably as good as anything around commercially and wrapped up nicer - worth a look!

Then imagine taking the battery pack out and putting an engine in that could do 200mpg+

http://www.vectrix.com/Portal/3/Languag ... /Home.aspx

[lex]

I've seen some seriously quick 'straight' electric bikes, even a 300hp+ drag bike called the 'killacycle'!!!
There's also a diesel electric on the private conversion page of this site, though no specs are given, it looks like a feasible conversion. A maxi Scooter style hybrid would certainly be an interesting project as mentioned by Greg.

Personally I'm coming at the diesel bike from the 'eco' angle (better fuel economy and potential to use veg oil) and recycling an older bike I'm trying to keep it as simple as poss and making use of stuff I have already. That's the reason I did not choose straight electric initially. Maybe when battery technoloy makes more progress I'll build a bike and have it charged from a permanent magnet wind turbine and a 1kw solar array (Lottery win my help there too!)


Lex

[Ih8Suvs]

You are on the right track Greg. Its basically what a hybrid vehicle uses. Small engine to supply continuous demands, chosen so that at its most likely average demand it is operating at its most efficient power setting, electric for good acceleration, and a way to re-capture braking losses. In city traffic braking losses are huge. It is the reason that vehicles get worse economy in the city...except for hybrids that do what???...Right!!! Recapture braking losses. I really don't think it matters if all the drive goes through the electric powertrain or just a percentage of it, what ever works out the most efficient.

And anyone doubting the power to weight ratio and efficiency of rare earth magnet motors need look no further than to the electric radio control airplane crowd. Buy yourself a motor and play with it. Look at some of the competition motors. Impressive. Scary powerful. Feather light. Watch your fingers..or arms..

A motor/generator/regen braking controller I think could be designed by any half competent EE. I wish I was even a 1/4 competent EE. Oh well I have good friends.

I have thought about the same diesel electric concept except for a light three wheeled car on the styling and size lines of the failed Corbin Merlin. Which is probably exactly what my three wheeled car will look like since I already have a Corbin Merlin body that has been taking up precious garage space for the last several years. It is light, it looks aerodynamic enough, Corbin claimed it was. I don't have a wind tunnel though so will probably have to make it move to tell.

What could make all this stuff work all the better is a light common rail turbodiesel engine, available and affordable to tinkerers such as ourselves.

Tim

[taildraggin]

Interesting idea, you may need some batteries as an additional reservoir.

Off topic, but related, I've been watching something called 'hypermiling' on the web. A gent in Florida with a stock Ford Escape hybrid has figured out how to improve mileage using his driving technique to take advantage of the components. It's a 200 hp V6 SUV hybrid getting 45 mpg (5.2l/100km) and he can 'play it' to over 70mpg (4.3l/100km). Encouraging.

http://www.cleanmpg.com/forums/showthread.php?t=350

[oilburner]

greg123 wrote:

Also you wouldn't use an alternator generator. We are not talking a heavy unit to bolt on - alternators are very inefficient - we are talking a unit using a 'flywheel' as the spinning componant and built round it. Realistically probably 2 inches out of the end of the engine would be enough, these rare earth magnets are VERY powerful so you can keep them small and having a magnet field rather than an electromagnet field (alternator) makes them efficient - it's the exact same technology used in all good wind turbines where the generator is compact, relatively light and doesn't generally require gears (too much friction losses) and is very efficient to capture the little wind power.

I think there might be some misunderstanding about alternators. First, I spent a couple hours surfing the net looking at the "generators" used for wind turbines to confirm my suspicion that the majority of them are in fact permanent magnet alternators (generator seems to be the generic term used in the wind industry), some with rare earth magnets. Second, not all alternators use inefficient electromagnetic field (I believe you mean rotor), they use magnets as have been used for the past 30 years in the majority of motorbikes - a rotating magnet (rotor) inside an electromagnetic stator which produces 3-phase AC which is then converted to DC by a rectifier. Nobody uses old fashioned DC generators with segmented slip rings (as opposed to AC alternators with a rectifier) anymore except for antique motorcycles and cars, hobbyists, schools and experimenters.

The rare earth alternators and wheel motors that are probably well suited for your proposed motorcycle application are custom manufactured by TM4, 105 miles down the road from me in Boucherville Quebec. These guys are leading edge in the field. If you've got a lot of spare change lying around, they have exactly what you want. Check their website:

http://www.tm4.com/eng/tm4energy/generators/

Their 10Kw (14 horsepower) generator unit which could probably be configured as a flywheel unit similar to their 40Kv unit weighs 46 lbs - quite a bit lighter that the 80 lbs of the 7Kw wind generator I quoted above.

The difference between a permanent magnet and an electromagnetic rotor as well as animated diagrams showing how typical 3-phase alternators work and are constructed and operate may be found at:
http://en.wikipedia.org/wiki/Alternator

FYI

Avery

[greg123]

Interesting company info, thanks!

By alternator, I was referring to the the sort in cars, typical in the uk from 1970-present, which have electric windings on stator and rotor. Now you mention it yes I do remember bike ones use magnet rotor (well, mainly the ones with internal crankshaft gens - external ones are often 'car' style.

Looked at the design of those very efficient gens from the company near you, they are packaged a bit different to what I meant though. They are stand alone and relatively 'long'. Citroen had a flywheel generator/startor combi a little while ago in the press, it's was very compact and comprised unit fixed on by the ring gear of the flywheel and another unit round the bellhousing on the inside. It generated 240v as well as 12v (probably just conversion) and operated as a starter and on hybrids would actually propel the vehicle as it started it, while being very compact.

I think that would be the trick, have a generator that was not 'seperate' and heavy, but a custom build where a flywheel was the rotor with magnet assembly round the edge an a large diameter but probably no more than 2in thickness surround (where the bellhousing would bolt in a car) stator with the windings. I haven't explained this very well, but essentially it would be a big ring running round an almost car sized (well as big as will comfortably fit on the back of one of our engines instead of a cvt pulley, maybe 12in diameter?) 'flywheel' with no seperate generator 'casing' allt he parts being fixed to the flywheel or backplate respectively.

Anyhow, here's dreaming!

greg123 wrote:

Also you wouldn't use an alternator generator. We are not talking a heavy unit to bolt on - alternators are very inefficient - we are talking a unit using a 'flywheel' as the spinning componant and built round it. Realistically probably 2 inches out of the end of the engine would be enough, these rare earth magnets are VERY powerful so you can keep them small and having a magnet field rather than an electromagnet field (alternator) makes them efficient - it's the exact same technology used in all good wind turbines where the generator is compact, relatively light and doesn't generally require gears (too much friction losses) and is very efficient to capture the little wind power.

I think there might be some misunderstanding about alternators. First, I spent a couple hours surfing the net looking at the "generators" used for wind turbines to confirm my suspicion that the majority of them are in fact permanent magnet alternators (generator seems to be the generic term used in the wind industry), some with rare earth magnets. Second, not all alternators use inefficient electromagnetic field (I believe you mean rotor), they use magnets as have been used for the past 30 years in the majority of motorbikes - a rotating magnet (rotor) inside an electromagnetic stator which produces 3-phase AC which is then converted to DC by a rectifier. Nobody uses old fashioned DC generators with segmented slip rings (as opposed to AC alternators with a rectifier) anymore except for antique motorcycles and cars, hobbyists, schools and experimenters.

The rare earth alternators and wheel motors that are probably well suited for your proposed motorcycle application are custom manufactured by TM4, 105 miles down the road from me in Boucherville Quebec. These guys are leading edge in the field. If you've got a lot of spare change lying around, they have exactly what you want. Check their website:

http://www.tm4.com/eng/tm4energy/generators/

Their 10Kw (14 horsepower) generator unit which could probably be configured as a flywheel unit similar to their 40Kv unit weighs 46 lbs - quite a bit lighter that the 80 lbs of the 7Kw wind generator I quoted above.

The difference between a permanent magnet and an electromagnetic rotor as well as animated diagrams showing how typical 3-phase alternators work and are constructed and operate may be found at:
http://en.wikipedia.org/wiki/Alternator

FYI

Avery

[sbrumby]

How about this for an idea. All electric bike, batteries quite a few, towing a trailer with diesel generator. No tax on all electric. Could trailer run on red legally ? Short distance no trailer required, long distance hook up and go.

[oldbmw]

How about this for an idea. All electric bike, batteries quite a few, towing a trailer with diesel generator. No tax on all electric. Could trailer run on red legally ? Short distance no trailer required, long distance hook up and go.

Rather than a trailer, why not mount the generator in a sidecar ?

I did once see a bike ( think dnepnr ) which had a wood powered gas generator mounted on a sidecar..

[greg123]

Volvo did that with a car. I am not sure I'd like to be hooked to a trailer most of the time (unless short distance commuting) but I think you might be able to get away without tax if the batteries it charges are 'unhooked' as if it's charging a battery that's connected to the motor it's a no no.

However, the efficiency of charging batteries is pretty awful and they can't take a quick charge, so essentially this doesn't work. That's why for effective regen braking you need capacitors, which can handle massive charging currents and are near 100% efficent in charge/discharge. Disadvantage is they are not good/cost efficieent or light for long term electric storage - not an issue with regen braking.

All 'trailer' EV's that I have seen have essentially been a diesel electric generator powering the vehicle directly, not charging batteries as it would be much cheaper to pay the tax and have a much more efficient direct drive from the diesel engine to the wheels and cut out the inefficient battery charging stage.

Interesting though. If battery technology develops further, sky's the limit.

Greg.

How about this for an idea. All electric bike, batteries quite a few, towing a trailer with diesel generator. No tax on all electric. Could trailer run on red legally ? Short distance no trailer required, long distance hook up and go.

[oilburner]

Since my first response to this post in which I expressed doubt that a practical diesel electric motorcycle could be built. I have done a fair amount of digging into the most recent technology. The more I dig, the more angry I become - IMO from what I've found, we could be driving cars and riding motorcycles *today* powered by the diesel electric concept greg123 proposed - it exists. The British company PML has converted a BMW Mini One to 4 hub motors with 160hp per wheel (640hp), a battery, an ultra capacitor and get this, a 30 lb / 20hp two cylinder gasoline powered onboard generator for automatic charging and long distance which by itself is capable of sustaining 60-70mph at 80 mpg!
Scaling everything down appropriately, a diesel electic motorcycle with excellent performance should be easily possible, if not initially cheap.

*Somebody* doesn't want widespread use of this technology

If you haven't read about the PML Mini, here's a good article for a start:
http://www.topgreencars.com/pml-electric-mini/

Avery

[taildraggin]

Technically feasible, but not yet market-ready may be more accurate. The math on mass producing useable EVs is still not good, though it's getting better. That mini is a very expensive car.

I did the numbers on the smaller Tango performance EV http://www.commutercars.com/ and it comes out above the cost to operate my current vehicle.

Using my local $.213 Kw/h cost(!) and a $4500/65,000 mile battery cost/life (both well understated on the website) the total cost per mile comes out to 24 cents a mile. That's a just a bit higher than my present vehicle. (Assumes 125k mile life.)

In my calcs, the TDI Golf comes out to around .16 cents/mile (lifetime). I used 250k mile life for the TDI. The little hybrid Ford SUV has numbers equal to the TDi's. Increasing the untested Tango's mileage to equivalent of the TDi's (not bloody likely), has them about equal.

For my commute, a plug-in would be great, but not at a cost above the crazy prices we have now with far less car.

It's good to see the solutions clearly emerging, though. I'm pretty sure that the future will be a plug-in hybrid.

[andrewaust]

Hi Guy's


I could see it working, but! A manufacturer may have to either build it or someone with the tooling and expertise in electrical stator winding etc may be needed if you are after a compact unit.

Keeping the above statement in mind, the diesel electric unit would be best made similar to the hybrid vehicle ones = compact. Maybe the V-twin Diesel with hybrid type stator/rotor unit?

The electric hub is a good idea, just copy the electric scooter/bike versions, but it needs to be worked out properly for power = kw, to be reliable.

Super capacitors (what they are called here in OZ) are coming down in price, so this also makes it cost effective.

The technologies there, just like our diesel bikes, no big manufacturers willing to get off there arse and have a go! Period. They just rather stick to old trends.



Cheers


Andrew

[jonnyr48]

my question is, is it possible to put the electric hub motor from greg's scooter on the back wheel of a low-powered diesel bike,to aid acceleration and recapture the acceleration energy,(thereby increasing the efficiency and mpg), or is it too difficult to co-ordinate two different drive systems to the same wheel?

[Crazymanneil]

My first post on this thread. Sounds interesting, what hub motor would you be thinking of? Anything heavy would add unsprung weight to the bike. How heavy would a (say) 100hp hub motor be and what would the cost be.

I'd feel confident you could find someone to design the controller circuit and the likes of MOSFET power transistors to work it all are pretty cheap nowadays. Ideally you would want the system to run at high voltages to reduce the current involved (thick wires, chunky transistors etc).

I know the alternator will add a bit of weight to the thing but then again you are removing the need for a gearbox/cvt. Sounds interesting the more I think about it (though I already bought a gearbox and primary drive!)

Neil

[jonnyr48]

hi neil, i didn't really mean replacing the gearbox, what i'm trying to figure out is how to add a smallish hub motor like the vectrix scooter greg talks about earlier in the thread (maybe smaller still?) to add boost to (and recapture the energy from) the acceleration of a small industrial diesel such as most people on this forum use, with a bog standard gearbox and drive.