Ideal Hub Motor Specs

[ekline309]

Ok guys, what are some features and specs you want in the ideal hub motor design?

What are some current limitations to whats on the market right now?

I'll start out by saying they are all way too big and heavy. Also, I think durability is an issue. It seems with the popularity of overvolting, they should be able to handle a large range of voltage input, say 24 - 72V? I also think there is some potential for regen.

Thoughts???

 

[Drunkskunk]

Geared or gearless?


For a gearless, I'd want something like a Clyte 4012 built like a waterproof Swiss watch.


as for a geared, The Puma seems to do everything right. Weatherproofing it would be nice.

 

[safe]

The smart guys are all into RC motors now.

You might check the "E-Bike Non-hub Motor Drives" threads.

 

[markcycle]

The smart guys are all into RC motors now.

You might check the "E-Bike Non-hub Motor Drives" threads.

Just not true there are smart guys working on hub motors also
Mark

 

[Drunkskunk]

The smart guys are all into RC motors now.

You might check the "E-Bike Non-hub Motor Drives" threads.

Of course the thread was titled "Ideal Hub Motor Specs".

Just because some of the people who like to tinker with new things are playing with RC toy motors and bikes, doesn't mean they are the best way to go.

 

[Toorbough ULL-Zeveigh]

geez, ya give the RC crowd their own gazeebo to play in & it's still not enuf,
"How may gazeebos do you she-males need anyways?"
The 'smart' guys also went with betamax & HDdvd.
and along the same ded end, batteries in tubes.

Taking better advantage of regen is strictly a function of the controller.
The hub motor is just being driven as a generator.
There might be some physical changes that could be made to optimize it in the direction of being a generator but they usually come at the expense of motor performance.
Take a look at the E+ @ electricmotionsystems, it has 9 levels of regen using a space-vector controller making it probably the most advanced in this area.

One thing I want to see in a hub motor & I'm patiently waiting for is multitap windings & a controller to match.
Not quite the equivalent to a geared hub but electronic gears at least go a long way to extend the useable rpm bandwidth & efficiency of a hubbie.

Actually there is another feature that might be a simpler to implement is phase advance, again a controller to take advantage of it.
If it improves lower speed efficiency enuf in high voltage setups maybe the poor deluded 'smarty' guys will finally STFU.

yeah, I don't believe that either.

 

[Mathurin]

The hub should have two mechanical gears, two windings, A built in heat sensor, no hall sensors, weigh <2kg, require no more then a yearly oil change as maintenance, internal gears & bearings to last >25K kms between (easy to perform) servicing. Be available in spoke counts other then 36, and most of all: be designed to fit existing bicycles...

Controller should be able to do transparent adjustments in function of speed and load so as to maximize eff in all circumstances, switching between gears, windings, voltages (say, 24-48v system) and trim the timing. Also sine wave commutation rather then square. Throttle designed to be transparent also, so that riding the bike simply feels like you're superman up to the speed limit.

 

[TylerDurden]

The smart guys are all into RC motors now.

 

[John in CR]

Lightweight, durable, waterproof, are already mentioned, but to truly be ideal it's gotta include a 2 or 3 speed transmission in there for efficient running up big hills as well as on the flats, and for the icing on the cake how about low cogging for easy pedal only but no freewheeling, so regen is possible.

John

 

[dogman dan]

I thought big and heavy was why they could be overvolted. They might be lightend up some, but not much since copper weighs what it weighs. Vents that help cool the motor without getting a bunch of water in would be good, along with internal fan blades to help move the air through. This would also help clear the motor of condensation moisture. If that is impractical, at least cooling fins on the hub to conduct some of the heat away better. And for sure, better threads and nuts on the axle so we can torque down the axle nuts enought to prevent spinout without stripping them out would be the first thing!

One thing seems obvious to me, most of the things we want to improve about a hubmotor are inherent to them. But that doen't mean the hubmotors advantages are canceled out.

 

[fechter]

Two gear ratios built in would be very cool. A granny gear for climbing really steep hills and a flatland gear should be enough.

What really sucks on most of them is the axle/torque arm arrangement. What's really needed is an integrated torque arm that is bullet-proof. Heinzmann motors are a good example. The torque arm needs to be inside the dropout and attached to the axle with a spline or something. It would need to be removable for servicing the motor with most designs, however it may be possible to permanently weld a torque arm on one side and build the motor so it can be assembled from the other side.

The other lame feature on most of them is the hollow axle. It should be done like the Xlyte 5 series motors where the wires exit from the edge of the axle, not through the middle. And have plenty of space for fat wires.

What you could borrow from RC tech is high quality iron, magnets and copper. This will improve efficiency and reduce heating.

 

[ekline309]

So far:

1. 14 mm axles
2. Lightweight, durable, waterproof
3. 2 speed transmission
4. Built-in torque arm
5. 24-48v
6. High quality iron, magnets and copper
7. Multi-tap windings

 

[Toorbough ULL-Zeveigh]

multi-tap is either/or to compensate for the lack of a mechanical transmission.
dual-wind would be plenty if you include gears.

The other lame feature on most of them is the hollow axle. It should be done like the Xlyte 5 series motors where the wires exit from the edge of the axle, not through the middle. And have plenty of space for fat wires.

yeah, forgot about that I've taken it for granted already.
I like my hollow axle, put to it's proper use tho, with a skewer thru it, & agree, the wires exiting next to it.
They weren't the first to do it but in my biased opinion you can thank Tidal Forces for showing the way on that.
You may think otherwise but on my wish list hub motors should come standard with a QR & an integrated beefy torque-arm that makes skewering possible.
With the higher rate of punctures if I didn't have the QR, patching would be a time consuming painful ordeal, well, moreso.

 

[recumbent]

Controlers need to be more intelligent, I think Infineon is doing that already, I'm buying one this winter.

Use a geared hub system with oil bath, can't be that difficult, transmission seals keep stuff dry for years.

These are easily doable things. I had a geared hub motor for years, and it was almost perfect, except minor noise on acceleration, and lube, also minor.

 

[dogman dan]

Any really signifigant improvement in hub motors is bound to involve gears. A high low selector would be sweet, even if you had to stop to flip a shift lever on the hub. But a robust enough gear motor run at 72v wouldn't need different gearing.

 

[ekline309]

Let's say one was trying to develop a 2 speed brushless rear hub motor, any ideas on how this might be accomplished??

I've been looking for hub motor design diagrams and haven't been able to find any of those either.

 

[Miles]

Let's say one was trying to develop a 2 speed brushless rear hub motor, any ideas on how this might be accomplished??

Some ideas: http://www.diro-konstruktion.de/Englisch/index2.html

 

[recumbent]

Wow, some facinating ideas on that link, thanks Miles. Here are a couple pics for those that are too lazy.

 

[ekline309]

Thanks for reminding me why I'm not an engineer... I wonder if this is in production right now??

 

[Miles]

Another possibility is something like the old-style Sanyo hub , which has an eccentric motor, but with a retro-direct drive: http://endless-sphere.com/forums/viewtopic.php?f=28&t=7679