Axial flux hub motors.

Ianhill

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Sep 25, 2015
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Why dont we see axial hub motors in use more often?

Stand up scooter have tapped out the hub motor and gone to a dual setup to get the power needed to pull a human at a decent speed, 5kw or so for around 30 seconds and the motor gets too hot prolonged abuse at this level will see it enter the shadow realm early in life.

These small motors are perfect for axial they can use cable techinoques from the latest hub motors to get the cables in and out without drilling the shaft and have a water loop entry on the opposing side so not only can the power density be increased it can be maintained for more time.

One hub could equal what 2 is doing now making the ride alot more powerful or lose about 5kg around a tenth of its weight up front and thats alot when its only 50kg to start with.

Be nice too now peoples opinions on why its not about yet on any type of ride ?
 
Go for it and build one! :D

I have no real clue what the big difference is between axial winding and regular but I know that all formula student electric cars use axial motors, too (their favorite is a motor from emrax, they specialized on axial flux outrunners).

Personally, I´d like to see a rear driven scooter with >5kW peak, IP67 rated and under 30kg. I´d buy it instantly, now thinking of building one that fulfills my needs..
 
APL said:
Axial rotors don't
like side loads very much.
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viewtopic.php?f=30&t=85996
 
I had a look through that thread but looks to be nothing factual of use to me, im not sure where apl comment came from but side loading on the covers could be worked around.

For me to make a prototype motor in the uk without having free access to a machine shop and the materials would be beyond my turnip a week wage packet.

Id like to get a design together though in a 6.5 inch hub design following the same 150mm dropout amd disc standards so the hub is interchangeable with the desire scooter, for me im thinking the nami burn e viper.

Theres a new wolf gt with a 21700 pack but it used a 7p pack of lg cells that have 70 amp max and pull 100amp from them bad design the capacity will drop heavily at high loads, the nami uses 10p of panasnic cells same 100amp max but its cells can handle that continuous and the acceleration shows the nami is heavier no more powerful controller wise but beats the wolf gt specially after a few heat soaking runs.

Anyway off track a bit but i dont have faith that kaabo etc will deliver anything soon.
 
The best bang for your buck is one of the common radial direct drive hubmotors.

Because of this, they have been mass-produced in a very competitive market (China), and this mass production has widened the cost-effective gap.

There's nothing wtong with axials. Motenergy made them, and so did Lynch-Agni.
 
I dont think theres much difference in the manufacturing costs of them its more to do with the design engineer's taking whats been done and repackaging it rather than innovate which is likely led by the top dogs in the office saying costs to much cut corners or your taking to long hurry up etc.

Innovation takes R+d time money and effort all things no one likes to give up for free so there has to be a calling by the people or an opportunity for a brand to rise, at the moment i dont see it for the average user radial is good enough people die on scooters as is so a 100mph capable ride would need a special type of controlled idiot to not kill themselfs or others around them in the process leading to a legality issue would you be the company that released a scooter that has the highest desth toll per rider it would have to be named the widow maker and make a spectacle of it been doped with mechanical steroids.

Kaboo for example went from a working 18650 battery to a not good for purpose 21700 but pushed it as a good move because its cheaper for 140 21700 cells vs 200 18650, so what other cost cutting exercises go on to please management.

Nami viper seems a good build when you break it down everything copes as intended for prolonged use and good cycle life on the cells even with a harsh rider, but the new 21700 gt warrior will need a new battery in 2 to 3 years and change to a high discharge cell dropping capacity from 35ah to 29ah but thats actual there to use and alot more too then making it beat the nami at that point but as is in cold weather a kaboo will drop on its arse a nami will walk past it.
 
Guess I should comment on the quote, "axial rotors don't like side loads very much",.. coming from a post where a
bike rim was to be spoked to an axial rotor. Perhaps I should have been more specific.

Since axials with steel cores rely on a 1mm air gap on the sides, then sideway pressures on the 'very outer' diameter
of the rotor 'can' have an effect on the gap. Not always,.. depends on the design and how strong it's made. Air cores are
probably less susceptible to this having wider gaps.

Just suggesting, (in that post), might be best to avoid any potential problems by spoking to the axle, as in the D500 motor,
instead of the outer diameter, as in most hub motors.

Radials are a little less likely affected by diameter side loads because the gap is radial.
 
Traditional ebike hub motors have been very long vs their width so rpm has been traditionally slow but good torque production.

These high power scooter motors are more square half as wide as they are tall making them spin alot faster by design.

This square design will lend itself to rotor strength quite easily as the side cover will only span under 100mm between supports.

The magnets would have to be smaller than normal axials been a near square design so the thickness would be thicker to get the field strong enough.

This got me thinking improvement number 2 could be the magnets would be easy to arrange in groups of 4 to make a single pole up with a halbach array to boost the potential even further.

Would i have a go at it not without lots of peoples input so i can get a clean emf waveform and ample inductance to make it easy for vesc to run in FOC mode, a decent vesc would need to be sourced to power such a beast and the cost and complexity goes up, im not one to shy away but i know when its beyond my reach.

I can not copy yourself APL your a legend done it with little help in my eyes you have done what i can only dream of even if your suffered a stumble, you ask a fighter its the losses that drive you to dig deep hit it harder im sure it aint over yet with personal growth you will be back swinging to slay the axial beast.
 
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