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- Thread starter D-Man
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knightmb
100 kW
Looks like a nice ride, not much info on the range or power though. I agree, not sure why the front wheel is laced this way. Is there some advantage to more complex lacing geometry or is it just to turn heads?
Geebee
1 kW
http://www.australiancyclist.com.au/showarticle.php?s=4&a=1621
Review of the Avanti.
Review of the Avanti.
xyster
10 MW
Thanks for the review link!
What do the brains here know of axial flux motors? Sounds like a play on Back To The Future's 'flux capacitor' time warp motor. The Avanti motor appears very large and heavy for its rated power.
What do the brains here know of axial flux motors? Sounds like a play on Back To The Future's 'flux capacitor' time warp motor. The Avanti motor appears very large and heavy for its rated power.
lemmiwinks
100 W
LBS here has one in stock. Too rich for my blood!
Etek's and Perms are axial flux. I think Heinzmann motors are conventional (radial flux).
I don't think there's any real inherent efficiency advantage to axial flux. It's more a matter of packaging and form factor. You can make an axial flux motor thinner for the same power rating. It might be easier to make an ironless motor in an axial configuration, but these are rare.
Nick, I'll be interested to see any pics. There must be some copper in there somewhere.
I don't think there's any real inherent efficiency advantage to axial flux. It's more a matter of packaging and form factor. You can make an axial flux motor thinner for the same power rating. It might be easier to make an ironless motor in an axial configuration, but these are rare.
Nick, I'll be interested to see any pics. There must be some copper in there somewhere.
It appears that the motor for the bike has been adapted from a fan motor? :?
Ok here's some pics. Its a lot more complicated than i thought, i was expected a normal (radial) brushed motor and a few gears 
Quite complicated to photograph so i've taken loads. There are 3 main parts. The outer case or hub case which rotates and is connected to the gears via a freewheel inside. Then there's inner housing which is the mtoor case,the axels, the stator (plate with magnets on), the brushes and on the otherside the gearbox. This part is stationary and the hub case spins round the outside as the wheel turns. The thrid part is the drive system, consisting of the armature and the gears, i've not figured out how high the ratio is, the motor is design to go 16mph at 36 volts.
outer/hub case
hub case side - the freewheel is in the centre
inner housing
windings
windings with rear plate on, inside the motor housing
brushes
[/img]
Quite complicated to photograph so i've taken loads. There are 3 main parts. The outer case or hub case which rotates and is connected to the gears via a freewheel inside. Then there's inner housing which is the mtoor case,the axels, the stator (plate with magnets on), the brushes and on the otherside the gearbox. This part is stationary and the hub case spins round the outside as the wheel turns. The thrid part is the drive system, consisting of the armature and the gears, i've not figured out how high the ratio is, the motor is design to go 16mph at 36 volts.
outer/hub case
hub case side - the freewheel is in the centre
inner housing
windings
windings with rear plate on, inside the motor housing
brushes
[/img]
xyster
10 MW
Geez Louise, you have to go through all that to change the brushes? For an ebike, why go with a brushed hubmotor?
xyster said:
Nah, changing the brushes is quite easy. I just took the rest of it apart for fun. The guy i bought it off also said there was a clicking noise so i wanted to check out the gears. I got a few of these bikes quite cheap to do mods on and also fix them up as bikes for friends. I was quite impressed with specs in stock form only 250 watts but quite good performance.
Great pix, that's a real interesting design. I've never seen one like that.
Sure looks messy.
Sure looks messy.
Reid Welch
1 MW
Wow, thanks for the photo essay, Nick! Reapplying your post here atop the fresh page:
The potted windings, ironless, right?
Ferrite magnets hint that this design is years old, as do the brushes.
Yo, Xyster, advantages of brushes for a light-duty motor? Sure makes for silky, torquey low speed operation, plus,
the controller can be small, cool running and hidden away, and cheap.
I wonder how they manage to really keep the grease from ever creeping onto the commutator, fouling the brushes? Otherwise, there's no harm to a motor from grease or oil everywhere.
And only two brushes despite eight poles.
I wish I knew the axial motor science.
I should google, eh Mathurin?
---
Apparently, the Avanti motor is not geared.
I can't tell if it's brushless though--who knows?
According to Avanti's PDF brochure (2003):
To bad for that typo.
The Avanti has been out for years, without apparent change.
A good design overall, or massive overstock?
It its way, Nick, that Powabike motor seems roughly mechanically-analogous to a currie-type drive, just inbuilt to a hub; all that gearing.NickF23 said:Ok here's some pics. Its a lot more complicated than i thought, i was expected a normal (radial) brushed motor and a few gears
Quite complicated to photograph so i've taken loads. There are 3 main parts. The outer case or hub case which rotates and is connected to the gears via a freewheel inside. Then there's inner housing which is the mtoor case,the axels, the stator (plate with magnets on), the brushes and on the otherside the gearbox. This part is stationary and the hub case spins round the outside as the wheel turns. The thrid part is the drive system, consisting of the armature and the gears, i've not figured out how high the ratio is, the motor is design to go 16mph at 36 volts.
outer/hub case
hub case side - the freewheel is in the centre
inner housing
windings
windings with rear plate on, inside the motor housing
brushes
The potted windings, ironless, right?
Ferrite magnets hint that this design is years old, as do the brushes.
Yo, Xyster, advantages of brushes for a light-duty motor? Sure makes for silky, torquey low speed operation, plus,
the controller can be small, cool running and hidden away, and cheap.
I wonder how they manage to really keep the grease from ever creeping onto the commutator, fouling the brushes? Otherwise, there's no harm to a motor from grease or oil everywhere.
And only two brushes despite eight poles.
I wish I knew the axial motor science.
I should google, eh Mathurin?
---
Apparently, the Avanti motor is not geared.
I can't tell if it's brushless though--who knows?
According to Avanti's PDF brochure (2003):
To bad for that typo.
The Avanti has been out for years, without apparent change.
A good design overall, or massive overstock?
Yes the motor has an ironless rotor, which is supposed to reduce core losses and has zero cogging. The magnets look like rare earth to me. They're too thin to be ceramic. Don't let the color fool you, they're just epoxy coated.
The two brush setup is wierd, but I've seen it on quite a few motors.
More brushes would add friction. More brushes would also increase the current capacity of the commutator. It doesn't seem to change efficiency from an electrical standpoint much. Two brushes will handle enough current to fry the windings, so more won't help (in theory).
I suppose the motor shaft bearing is sealed where it goes to the gearbox and centrifugal force would sling the goo away from the center, so lube leakeage onto the commutator is minimized. Any lube on the commutator is usually very bad.
Here's a very similar ironless disk rotor made by Kollmorgen:
Kollmorgen's disk is obviously more precicely made (and more expensive).
The two brush setup is wierd, but I've seen it on quite a few motors.
More brushes would add friction. More brushes would also increase the current capacity of the commutator. It doesn't seem to change efficiency from an electrical standpoint much. Two brushes will handle enough current to fry the windings, so more won't help (in theory).
I suppose the motor shaft bearing is sealed where it goes to the gearbox and centrifugal force would sling the goo away from the center, so lube leakeage onto the commutator is minimized. Any lube on the commutator is usually very bad.
Here's a very similar ironless disk rotor made by Kollmorgen:
Kollmorgen's disk is obviously more precicely made (and more expensive).
Reid Welch
1 MW
Thank you for the correction about the magnet material and for the other wanted-education. I love to learn.
The Kollmorgen is a beauty! Is it brushed?
I still like brushed motors for this reason: No dealing with large, hot-running, flunky X-lyte (my bad!) controllers. I am still stupidly retrograde, for no really good reasons.
For the Powabike motor, the absence of cogging by that ironless design
(brilliant point you made there), won't be a factor, inasmuch as it's a freewheeling thing.
But for the other motor? Gearless hub motor? Ironless and no cogging=faultless feel to the pedaler, and a weight savings too, yes?
Wow, again, that Kollmorgen is luscious looking. Can it be force cooled?
Many thanks! Hail fechter! Braintrust-in-Chief!
(no fair blushing, bud)
The Kollmorgen is a beauty! Is it brushed?
I still like brushed motors for this reason: No dealing with large, hot-running, flunky X-lyte (my bad!) controllers. I am still stupidly retrograde, for no really good reasons.
For the Powabike motor, the absence of cogging by that ironless design
(brilliant point you made there), won't be a factor, inasmuch as it's a freewheeling thing.
But for the other motor? Gearless hub motor? Ironless and no cogging=faultless feel to the pedaler, and a weight savings too, yes?
Wow, again, that Kollmorgen is luscious looking. Can it be force cooled?
Many thanks! Hail fechter! Braintrust-in-Chief!
(no fair blushing, bud)
xyster
10 MW
I reasonable point that I think, after reading Fechter's experiences, is a big reason I prefer brushless: when brushed controller FETs blow, the result is a dangerous 'flat-on-your-back bike down the street' short to the motor. I don't feel as safe on my brushed scooter anymore. Other reasons: no changing often difficult-to-find brushes every 5-10k miles; better efficiency; better voltage/rpm range; quieter.
My brushless hubmotor/xlyte controller combo has operated flawlessly for 1000 miles now. And when it's time for new brushes on the scooter's motor, I'll probably just replace the entire unit with this instead (or something like it):
http://www.poweridestore.com/Scooter-Hub-Motors/12-Scooter-Motor
Yes, the Kollmorgen disc motor is a beauty. It is brushed, with two brushes arranged like the Powabike motor. It came from a medical centrifuge, but is only rated for about 100w and has a huge housing.
I think it redlines at over 20,000 rpm.
The winding arrangement is very similar to an Etek.
A disc could definitely be air cooled. One disadvantage of the disc design is the low thermal mass. If you over amp the motor, it will overheat very quickly.
I think it redlines at over 20,000 rpm.
The winding arrangement is very similar to an Etek.
A disc could definitely be air cooled. One disadvantage of the disc design is the low thermal mass. If you over amp the motor, it will overheat very quickly.
I'm going to play around with it a little bit i'm still curious to see how fast it spins, play with the brushes adjustment/timing or even if it works at all. There was a guy on the old forum called scott C who had one up to 72volts so hopefully it will be fun.
Reid,
is the new currie brush motor also a disk motor?
I'll try to remember that, i've got a bad track record with brushed motors. One advantage of brushless motors, a bit more idiot proof
Reid,
is the new currie brush motor also a disk motor?
fechter said:
I'll try to remember that, i've got a bad track record with brushed motors. One advantage of brushless motors, a bit more idiot proof
Reid Welch
1 MW
Nosir. Here are its parts, photographed when I first ventilated it for force cooling.NickF23 said:
In the group you see an extra brush-end cover plate, salvaged from the first Unite MY1018 which had burned out.
That cover, with a large nipple (not then installed) became the new motor's plenum cover.
If I did this mod over again (will do someday), I'd augment the perfs for less wind resistance.
I am not understanding how iron mass "helped" my first Unite withstand copper heating in any useful way;fechter said:
more like the opposite, I think
The slots are insulated (that's thermal insulation also) and contain only a portion of the winding, but...
the most dramatically fried windings were those within the slots, blanketed thereby.
xyster
10 MW
Reid, did you fry your first motor by overvolting, overamping, or both? Other small brushed motors seem to hold up well to 1.5x overvoltage, often with no extra cooling.
Interesting question. In theory overvolting with current limiting won't increase the motor temperature because heat losses are proportional to current. Of course there is more friction because the motor spins faster but i imagne this creates only a tiny amount of heat. But maybe, at a given current, a fast spinning motor will transfer heat away from the armature to the outside case faster? Does faster moving air transfer heat more quickly in a sealed unit?
Reid Welch
1 MW
In practice, no, not nearly enough.
Not even if I'd water cooled the outer case when I ran that motor so hard as I did on its D-day; it would still have fried
because the current at 36V pressure put an estimated 25 or more amps through the windings on that several-mile-long high speed road test of the 36V performance. There's hundreds of watts of waste heat to carry off.
Air-through is the only way here.
36V ran the bike at 24mph instead of the stock 24V's 17mph.
The copper resistance is one cause of the heat.
The magnetic inefficiencies at such high flux must account for the rest of the destructive heat.
When I run the motor now with forced air ventilation, it remains relatively cool on the exterior of the case.
I find that on humid days the motor runs positively cool.
If the ambient air is dry, the motor runs fully 20F hotter on the exterior.
At any rate, force cooling does allow this tiny motor to live on 36V and double the rated current.
It's not battery-efficient when over driven like this,
but in consideration of the low cost of the motor, its low weight and robustly simple construction and ease of service and all that stuff;
its not being in the wheel, etc,
I can live with the former tiny toaster's waste of energy, for now.
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