Ginormous outrunner.... in my washer!

dave.com

dave.com

10 mW
Joined
May 12, 2009
Messages
32
Location
SF Bay Area
The really cool thing is the armature is _ironless_. Had I not stupidly unscrewed the shipping bolts all the way, trapping a 6" long standoff inside my brand new Samsung washer, I would have never removed the access cover and discovered this gem. http://davedesign.smugmug.com/Machines/Ironless-outrunner/22561518_VWkQSZ#!i=1805634620&k=QqcmxMK

It's about 300mm diameter, and there is absolutely no cogging. Can is stamped steel, armature hub and coil forms appear to be some polymer, maybe a thermoset? Can't imagine heat dissipation would be that great though. Max spin rpm is listed at 1200rpm (it's direct drive), so it might make an interesting hubmotor. ...and magine all the cool stunting you could do with the washer controller.
 
I had a similar motor in a Fisher Paykel washer. I understand this type of motor is common in appliances now but power is limited by the magnets.
 
That design wouldn't work ironless, nothing to guide the flux.

My guess would be the plastic is on the top and bottom of the lam stack to protect the edges of the wires from cuts and abrasion during assembly and vibration during use.
 
There is a marginally better picture here http://www.ebay.com/itm/ws/eBayISAP...f%2FRBKqsLU%3D&viewitem=&orig_cvip=true&rt=nc Courting certain disaster and apocalyptic flooding of my laundry room, I pulled the cover off again to have another look. The stator structure does look like it's all plastic, but nearly impossible to see at the tip of the stator coils is what indeed appears to be the end of a lamination stack. Peering into the area under the coils (towards the center) I can't see anything metallic, but the "intra-coil" lam structure may be hidden by the plastic. I turned the drum again and there really is no cogging torque, maybe due to magnetic design.

In a way, this is good news for traction applications, as the drive electronics for an ironless design might be tricky, at least from what I have seen from the CSIRO and Coconi ironless stator drive designs.

liveforphysics said:
That design wouldn't work ironless, nothing to guide the flux.

My guess would be the plastic is on the top and bottom of the lam stack to protect the edges of the wires from cuts and abrasion during assembly and vibration during use.
Click to expand...
 
It looks like an easier rig to work with than the F&P.
 
I'll know in about a week. Not to derail my own thread, but there is an Interesting pdf on the F&P site http://www.fisherpaykel.com/direct-drive-motors/common/pdf/4876_NZ_Motors_BRO_HR.pdf. Worth downloading for the cover pic alone. If the "MB" motor can really do 50nm @ 1600rpm, that would be around 8kW, but I doubt it could sustain that for long. I don't get their "Nm / WattsLoss-2" spec though, is that just a weird way of showing torque constant?

TylerDurden said:
It looks like an easier rig to work with than the F&P.
Click to expand...
 
As with many of my impulse motor purchases, this one turned out about like you'd expect...
More images http://davedesign.smugmug.com/Machines/Ironless-outrunner/22561518_VWkQSZ#!i=1805634620&k=QqcmxMK

Phase to phase resistance is about 12 _ohms_, no, not miliohms. It's Wye, as can be seen in the pics. More info:

12 glued in magnet segments, each of which seems to have 4 poles, for a total effective magnet count of 48.
Magnet width, ~40mm.
Magnet material, unknown, does not look like neo.
Rotor inner diameter ~260mm
36 slots (ABCABCABC...?)
Stator width ~34mm

Like the FP, this probably wants a controller with 300V dc rails. It has a label on the can that says something like 1300RPM, which means a single digit kV. Good news, it would be cake to rewind (for someone who knows anything, which is to say, not me). There is lots of room between slots, and nice soft plastic with rounded corners. The same plastic that will turn to string cheese when you try to feed this thing more than 10A. This is, as I expected, a "frameless" motor, so would obviously need structure added to connect it to something.
 
From a structural perspective, I would expect that increasing the power output from that motor would shorten the life of those ironless (?) cores - that plastic looks like it would creep and fail under much more than the load it was designed to have (turning a washing machine drum). I guess you could make a replacement stator of the same design using laminations of iron...?

Chris
 
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