Aluminum windings for hub motors

recumbent

100 kW
Joined
Sep 7, 2007
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Location
Okanagan valley Canada
I understand wraping aluminum wire around a core would be difficult. But i know it can be done because we had such motors on our CNC grinders. The motors were about one horsepower (AC) but they were constantly start/stop operation and the motor hub was super light so it can spin-up fast.

I realize cost is an issue but so is weight, especially on a bike. These 15-25 LBs of copper is rediculously heavy.

Is it possible to make an efficient hub motor incorperating lighter components, like aluminum?
 
Aluminium windings would have to have a cross-sectional area 64% larger than copper, but would weigh only 49% of what copper would. Those are for wires equal conductance and consequently resistance.

You could kiss any DIY repairs goodbye with aluminium, whereas copper can be soldered.
 
Not sure on the winding resistance compared to copper. I believe a lot of the really cheap stick welders are aluminium wound, comparativley light weight but they have a lousy duty cycle. Whereas old, quality stick welders, all copper, twice the weight for the same amps but you can weld all day and not worry about an overtemp trip.
 
I'm sure there's a way to do the math on it to find out what the possible benefits would be.
In a typical hub motor, the copper is maybe 25% of the total weight. The iron is what makes them so heavy. It would probably save more weight to stick with copper, but use a coreless motor with Hallback array magnets. You could get rid of almost all the iron.

Using aluminum has other difficulties that may be an overriding consideration, as pointed out above. There's a reason they don't wire houses with Al anymore. The fact that Al would need to be thicker might be a problem in a motor where the slots need to be stuffed as densely as possible.

Is there anything with better conductivity than copper? We'll have to wait for those high temperature superconductors :wink:
 
Malcolm said:
Silver then gold
But of course you'd want a transparent motor casing then :D
...and a very good security system.
:?
 
The Manhattan Project used quite a bit of silver for coil winding, several tons of it ... they couldn't get copper, as it was all being used to make ammo and radios.

The Treasury threw a fit at the request, and had to be threatened with harm by FDR. They did get every last ounce back after the war ended.
 
Okay, i understand it now, it's mostly the iron core that's the problem.

So, Gold wire wound motor (preferably braided) polycarbonate covers to see through, and get rid of the iron core. Got it, thanks guys. 8)
 
recumbent said:
So, Gold wire wound motor (preferably braided) polycarbonate covers to see through, and get rid of the iron core. Got it, thanks guys. 8)

Rollin' through the hood, 26 inch rims,
gold-wound core, 4110s,
cruisin down the street flashing ebike bling,
watchin' as the girlies stare and the boys say "Oh!"

8)
 
Also keep in mind the best substrate and material to use for making transistor is diamond. Prized for its thermal stability and indestructible construction.
 
We were just looking at a company that makes motors without iron cores.

http://endless-sphere.com/forums/viewtopic.php?f=3&t=4059

Would the greater expansion tendency of aluminum wires would loosen the coils over time?
 
yes! so for $33 million you cound maybe perhaps have enough to make a bike! here is the blurb:

NASA will pay Rice University $11 million over the next four years to develop an experimental power cable made from carbon nanotubes, the agency announced Tuesday.

The cable, also known as a quantum wire, would theoretically conduct electricity up to 10 times better than traditional copper wire and weigh one-sixth as much.

Scientists believe quantum wires could make spacecraft much lighter and more powerful, and may lead to faster computers and other commercial applications.

Under the agreement with NASA, Rice's Carbon Nanotechnology Laboratory is to produce a 1-meter-long prototype of quantum wire by 2010. To date, scientists have been able to produce wires no longer than several centimeters.

"This is a small step but a very significant one from our perspective, as we try to develop new technology that will help us as we send humans out from Earth and into space," said Jefferson Howell Jr., director of NASA's Johnson Space Center.

The researchers have no easy task before them. To succeed, they will first have to devise a way to produce perfect carbon nanotubes on demand.

Discovered in 1991, carbon nanotubes are tiny, molecular cylinders formed purely of carbon atoms. They are created by shooting high-powered lasers at a carbon target. Each nanotube is just one nanometer in diameter, or 10,000 times smaller than the width of a human hair.

Currently only 2 percent of all nanotubes can be used as quantum wires, and sorting these -- called "armchair nanotubes" -- from the rest is nearly impossible, according to Richard Smalley, director of the Carbon Nanotechnology Laboratory.

Researchers at the lab believe they can get around this problem by growing the desired nanotubes like crystals. By placing "seed" nanotubes in a laboratory reactor and pumping in carbon monoxide, or some other source of carbon, they hope to create perfect -- and long -- armchair nanotubes every time. Twisting these together will then produce a quantum wire like the one NASA wants.

"This is not a straightforward applied-research project where we know it's been done and we need to scale it up," said Smalley. "We're going to do major pioneering in this process."

NASA hopes to outfit future spacecraft with quantum wires rather than heavier copper wires. Doing so could shave critical pounds, which would save money on fuel and, ultimately, allow the craft to go farther into space.

Some engineers have also talked about building a 62,000-mile-long tether made of nanotubes for a space elevator that would carry astronauts and cargo into orbit.

"As we look forward to going to the moon, Mars and beyond, (nanotubes) will certainly, in my view, be a key part of doing that," said Howell.

Carbon nanotubes may benefit other industries, too. For instance, in 2003, NASA researchers described in the journal Applied Physics Letters how circuit manufacturers might create faster processors by replacing copper interconnects with nanotubes, which are more resistant to heat.

Other researchers have explored using carbon nanotubes to build next-generation flat-panel displays. The displays might feature a tiny nanotube-based electron gun behind each pixel rather than using a single gun for the entire display, like traditional cathode ray tube monitors.

In fact, carbon nanotubes seem so versatile that scientists believe they may one day end up in everything from batteries to military armor -- provided that they can be produced easily and cheaply.

"There is a new miracle polymer to be developed," said Smalley. "I believe this is a tremendously important objective for modern society."
 
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