MULE1.2 Axial flux test motor/bicycle specific

[liveforphysics]

On magnet spacing, I also remember from RC motor design that pushing the magnets up against each other was a fail. The magnets for Thud make a 8" OD disk when pushed together in a ring of 16.

They could be spaced out on a 9" or 10" rotor in a group of 16. Or, you could run a group of 14 on perhaps a 7.5" radius and keep some spacing.

The 14magnet 12 pole arangement seems to work out pretty well for many motors.

 

[rhitee05]

John,

For the most part the same principles and ideas apply to axial motors as to radial motors. If you imagine unwrapping a radial motor into a linear one, you can then re-wrap it in the other dimension into an axial motor. Sorry if that's a confusing visualization. If you look at just the path through the centerline of the magnets and coils (the average diameter of the magnets/coils), that should be directly analogous to a radial motor in terms of timing, etc. I haven't seen any good primer documents so far, the best suggestion I have is maybe some quality time with Google.

 

[Miles]

How about using SMC (Soft Magnetic Composite) prototyping material for the cores?

eg: http://www.hoganas.com/Documents/HIPIH/SMC/Somaloy_Prototyping_Material_2009.pdf?epslanguage=en

 

[Thud]

Miles,
That looks like some fantastic dope. I wonder how much it costs & if there is a US distribution network. My next question for them is if there is a mold-able product.

Eric,
Wow, good work & thanks for Modeling those flux configurations. Its good to see my suspicions confirmed on the overlap core config. Of corse you see I am attempting to stay as close to a flat 1 dimensional stator for ease of manufacture. Miles latest find there really opens the door for a more traditionaly lap wound stator. True "soft" magnetic material is hard to come by economicly from my searches.
I am playing with the idea of making the "split stator" teeth & laminated teeth imbeded through it (time to draw as words fail me) I think it may be very doable. That give us the ability to get lap wind configurations.
Lap winds with flat stock are still going to present hurdles. I speculate, but see the width as a problem. Given the flux densities atainable using cores, the flat stock may be a moot point.(untill we attempt the coreless stator, where I see nothing but potential on unlaped coil arrays)

Spin,
Thanks for the concern, I have also seen the frayed fingers from mis-hapes. I will use caution & respect while working with these facinating magnets.(young man...LOL) I will be constructing the current model I've shown with the disc magnets. I still want a smaller motor to test with & refine my manufactureing methods with before building Lukes "MEGA" axial motor. I think a lot of internet builders will make a motor for fun & I am all about open source.

I will have lots of photos of Jigs & machine set ups as I get into the project. I also have insiders at local fiberglass manufacturing companies & access to "samples" of some pretty cool composite stuffs.(West Mich has a deep product development comunity)I have no worrys regarding the end product, & I am really getting an education on electrical energy & its potentials. (never even knew it could be interesting a short time ago )

 

[Miles]

My next question for them is if there is a mold-able product.

That's how it's normally used, in production. You compress and heat the powder in the mould, to fuse it.

For a one off, I thought fabricating from blanks would be more do-able.

 

[Miles]

Here you go: http://www.hoganas.com/nah

http://www.hoganas.com/Documents/Published%20Articles/2009/PM09_16_EURO_PM2009_Hultman.pdf

 

[Thud]

Thanks Miles,
Looks like they are in Mkeefers area. I wonder if they would send a 50lb sample to an experimentor for full advertising & credits on the worlds fatest bicycle (I am sure Luke would accept the sponcership )

 

[Thud]

wow,
I just finnished a full read of the link, We are not as far behind in the technoligy curve as I suspected. That paper is from October of this year If I read it correctly. That is exciting, & there is that yoke less axial motor poping up again. I don't know about you all, But I am haveing a blast.
unfortunatly, duty calls as I have a venison to proccess this afternoon.

 

[Miles]

This is the corrected version of the double-coil connection idea.

There doesn't necessarily have to be a separate bridging piece. A single strip could be folded in the middle, or a coarse helical used, to align the starting points for the 2 coils, which are then wound alongside each other in opposite directions.

 

[Toorbough ULL-Zeveigh]

here's another SMC producer that might be closer to home.
corporate HQ in Geneva IL.
http://www.burgessnorton.com/index.htm



and here's an alternative axial coil winding pattern.
sorry i don't know the name of the italien nut it most resembles. triquetra? schmandorla??
for those that may have missed docbass' prawn pix from 2 years ago;
the avanti electra af hubmotor, along with a ceiling fan was one of the first offerings from the csiro spinoff InMotion Technology, tho it's nothing like the hubmotor from the solar challenge vehicle.
this comment from one bright lad was rather prescient.

That Avanti motor is cool. The heat from the windings can conduct to the outer surface directly, so cooling would be good. It would be possible to make a motor like that with two stators on either side of a single rotor. A geared version would be better.

http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=2565&p=36270

 

[Jonathan in Hiram]

I just had to say that the reversed double spiral flat strip winding is brilliant..

That is all.

 

[Miles]

Here's an illustration of the cross-over done with a coarse helix.

It's a bit like an Escher drawing, so I've attached a 3D PDF model (below), too....
[Click on the image in the PDF to activate the model - then click and drag to rotate.]

The coils could be right up against each other (with insulation), of course.

 

[John in CR]

Would there be any inherent problem with a soldered bridge between the coil halves? I envision putting them on both sides of a thin stiff plate of carbon fiber composite or whatever. Drill a hole for the bridge, and epoxy the coils in place, maybe with some fiberglass+epoxy around the coil to secure it in place instead of all that epoxy fill normally used.

Placed between two rotor plates aren't all the motor's forces on the stator parallel with the stator plate? Save the weight for the rotor structures that need more strength.

John

 

[Miles]

Something we need to consider: The thinnest Polyimide insulation tape available seems to be 2.5 mil (64 microns) thick. What is the minimum copper tape/strip thickness, to get better packing than stock enamelled wire.......?

 

[mwkeefer]

Thanks Miles,
Looks like they are in Mkeefers area. I wonder if they would send a 50lb sample to an experimentor for full advertising & credits on the worlds fatest bicycle (I am sure Luke would accept the sponcership )

Thud,

Closest "location" is in St. Mary's PA on the route to an old girlfriends home... the ride is about 2.5hr by car and there is no other method to get there (I knew I recognized the 814 area code). I suppose I would be willing to head up there for a day trip if we could somehow save a few $$$.

Wish they were closer... I do have alot of resources local, but nothing for this type of material (that I know of yet) - anyone need some teflon orings - you know the ones which failed on the shuttle disaster, manufactued not 1 mile from my moms house in the Aston, PA area - how about some crazy plastics, plastilake is there in the same complex.. Want a really nice lazer CAM machine? They are in the complex behind my office... Getting into this I have been spending quite some time searching out available local resources.

-Mike

 

[Thud]

Thanks Mike,
I will make a contact & see what I can arange for some samples. I really don't see myself setting up a true "sintering" proccess but the product looks right for our app.

Flat Copper Coil Stock:
I have looked at the copper foil from the stained glass suppliers & the gage is 1.5mills. That equates to roughly 26 or 27 AWG on .5"wide coil stock. is that heavy enough?
http://www.almetals.com/Coil_Suppliers/Copper_slitting/metals-copper-102.htm
here is a link to a specialty metal supplier that seems to have a better selection & could do a heavy'r gage if we need it.

 

[Miles]

Todd,

1.5 mil copper; 2.5 mil insulation is 30% copper......... I think we need at least 75%...

Anyone know the thickness of the enamel on stock wire?

 

[Miles]

http://www.cgstape.com/doc/tape_1mil.htm

http://www.kaptontape.com/1mil_polyimide_sheets.php

 

[Thud]

I suppose doubling (or tripling ) is an option.

 

[Miles]

I think we need at least 250 microns (10 mil) thick copper....

 

[Thud]

That sounds much closer to reasonable.
puts it in the 10 AWG range
The flat stock looks like it will be a custom cut from somewhere.

I only have the new spool of 14 gage wire & a 1/8 of a spool of some lighter stuff.

 

[Miles]

The data here - http://www.pupman.com/listarchives/1998/May/msg00404.html - shows an enamel thickness of around 1.5 to 2.5 mils (38 to 64 microns).

 

[liveforphysics]

The member RWP (Roy) paid for a third of the magnet cost! That was so nice! Thank you so much Roy! So cool to have a project work with support in many different ways from many different good folks in this great online community!



Thank you again for your generous Paypal Roy!

Best Wishes,
-Luke

 

[Miles]

The data here - http://www.pupman.com/listarchives/1998/May/msg00404.html - shows an enamel thickness of around 1.5 to 2.5 mils (38 to 64 microns).

The maximum theoretically achievable copper fill for 0.4mm round wire with 50 micron enamelling is about 65%. So, to aim for 75% plus, for flat strip, does seem about right. We also benefit from the better heat transfer, of course...

 

[Thud]

RWP,
Very generous. Many thanks. This is the first online comunity I have ever found where the folks actualy back up their good intentions with action.
I am inspired & humbled.

Miles,
I have allways had a question regarding the term "fill" as applied to stators. In some text it is speaking per-tooth & others seem to be describing the stator in whole.
Your context seem to re-enforce the " per tooth" interpratation.

I never had a chance to make any inqueries today, prolly not till after the hollidy this week (big shiping week & the factory floor is a bit behind.)
I am off this friday & plan a trip to the metal recycling yard in the next town south. I need some plate steel to make flux rings. Its allways fun to rummage around & see if any thing catches the eye.