The most basic axial flux design

[Gotwind Ben]

This was something I was hoping to supply as a kit, It doesn't look like it will happen unfortunatly now.
It is the alternator used in the Samrey wren wind turbine, designed and built just 30 miles from me.
http://www.samrey.co.uk/#/wren-micro-turbine/4530308127

As you can see, this is about as simple as it gets, an 8 pole single rotor 6 coil arrangment.
Samrey don't 'pot' either the stator or rotor in resin, just apply some kind of baked varnish on the coils.
I've seen 115 watts from this alternator, it is capable of well over that, 300 watts at high speeds.

It can't be that difficult surely to replicate this design, the bearing being the most tricky to get right I suspect.
also, the magnets are of a specialised size, it would need adapting to a stock magnet size.

Nice photos!

That IS about as simple as it gets!! Ben, it certainly would be very easy to offer a kit form of this alternator. I see a few laser cut parts, a CNC lathe job for the Bearing hub and for the shaft. And maybe a CNC milled stator plate from a phenolic plastic..or whatever. With a bag of magnets and a spool of wire, it could be running in about an hour or two. Maybe even supply a coil form for winding...

hmmm...If you lived here in Ohio, we could whip out a dozen prototypes in an afternoon.

I love this stuff!

Nice photos!

Rob

[Gotwind Ben]

Hi Rob.
I thought of you and your engineering equipment you have to hand.
It would be a nice kit to offer, sell like hot cakes on eBay, much better than the Ametek motors folk are scrambling to get hold of.

However.
Trying to beat the Chinese prices is tough, when you can get a complete unit for around £225 ($370), although it looks terrible.
http://www.navitron.org.uk/product_deta ... 3&catID=69

I do wish I lived closer and had access to some decent machinery, I was a toolmaker 15 years ago, and miss not being able to access a lathe and milling machine, one day..

In your photie Ben are those magnets just welded on to the faceplate?

[Gotwind Ben]

It does look like the magnets are welded, not the case.
They are simply glued with some kind of epoxy resin, there is also a laser cut steel ring to prevent any outwards movement caused by centrigual forces on the magnets, this could be replaced with hexaganol headed bolts around the circumfrance of the rotor plate.

Welding of magnets is not possible, I presume due to the magnets plating and the heat build up that could well de-magnetise the magnets.

hey ben,

have to laugh here. as one of the first things i do (like you) is to take any new toy apart and try to see how it works!

can you tell if there is a return plate behind those stator coils? looks to be Hugh's classic 4/3 layout. in this case 2 coils per phase. wow sure is some tiny diameter wire there! does it appear to be a multi strand in hand winding? i see samrey lists it as a multi volt unit ie 12/24v and with the low tsr blades the low rpm cutin won't stall it. i would have concerns about the durability of those plastic ties holding the stator coils in place.

looks like the outer ring of the magnetic backing is serving a dual purpose..to help keep the magnets in place as well as to stiffen up that very thin steel rotor plate. too thin.

is this unit using a proper bearing or a bushed bearing surface arrangement? from here it looks to be a long contact bearing surface with a simple spring clip in a groove as a fastner.

i've been collecting all the bits (when sale prices come up) over the summer for a winter project of working up an air core machine here on my coffee table with hand tools.

thanks for giving us a look inside that little bird.

cheers, dave

[Gotwind Ben]

Dave.
You are a clever man.
As I have met the designer locally, another Dave, I feel it is only fair to ask his permission on sharing details, he's a good guy after all.
I guess once a product is available to the public it is indeed open to replicating.

I don't want to p*** anyone off, not my style.

yes ben,

"I feel it is only fair..." i could not agree with you more there.

please do forgive all the questions, observations and assumptions about that neat little wren. afraid it was this defective gene i'm cursed with that forces me to do a product analysis on anything i see...forever driving my dear ladys eyes to glaze over with "hey dear look at this stress point here..it will never last more than 50 cycles like that....or this will still be working long after we are dust." that sort of thing.

we should remember that any work we are doing today is built on the shoulders of giants. and can only hope that in some way any tiny contributions we might make will help those that come after us.

generally someone doing a one off in private is of no concern as to IP, but we sometimes forget that an internet forum is nothing like a guy messing around in the work shack. the huge problem is that there are now national economies thriving by outright theft of IP and the r&d dollars behind it. it's interesting that some of the electronics designs are now potted with a tamper proof/self destruct layer to try to buy the innovator at least a small time window. the lockout codes on some of the programable electronic gizmos come to mind as well.

i'm excited to see that the diy/projects section of this forum is begining to spark to life.

cheers, dave

"what one man can do another can do" -sir hopkins in the edge

edit: corrected some weird spelling

When I see something like that I always find myself saying"whys it so expensive?"
That should be no more £100 not £500 :oops:

Hi Ben and all

Yes very nice to see inside workings of that turbine. I also love to take things apart and see how they work!!! and when you look inside there is not really much there at all. So I always think wind manufacturers are making a lot of money from not very much.

£500 is a lot for that type of turbine.

its only rated for 85 watts at 800rpm - so not very good!!! wow I would hat to guess how fast it would have to go to get to 300 watts

I feel the minimum size of turbine should be around the 500 watts per hour to make it worthwhile

Tim