The Halbach Disc Motor Ebike Project

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Condensed Version of this Thread
http://www.ebikehub.com/forum/viewtopic.php?f=4&t=2452&sid=c425f06c530db93310021b40a3990153

Cutaway View

If you take the disc:

...and slice it in half and look at the ends it would be like this:

...so I've been building up the "base" and will be adding the "sides" soon. The magnets will be attached to the insides of the "sides" that aren't there yet.

In the end you get a "Y" groove where the stator will fit. The stator holds the coils and it's attached to the frame much like a disc brake would be mounted.

Molds

When I get done I want to build a female mold of this so that in the future all I need to do is build the two sides by using the female mold and then assemble them afterwards. This will allow me to more or less "mass produce" them for a few more motors if the idea works well.

 

[johnrobholmes]

Should be a great start. I will be interested in the power you can get from the partial stator.

 

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Should be a great start. I will be interested in the power you can get from the partial stator.

My "guess" is that you get an amount equal to the proportion of the total. So if you create a stator covering 50% of the magnets then you get 50% of the output that is theoretically possible. However, the efficiency should still be good... 95% and above if it compares well to the CSIRO motor. Also, the open air design means very effective cooling.

I did an initial calculation a while back and estimated that given the added stength of the Neodymium magnets the volume and leverage (much wider disc means more torque) I'll be using should translate into something like 5 times the magnetic force compared to my old Unite motors. No way of knowing for sure, but just by thinking of the Torque = Radius * Force equation it seems that there is an abundance of leverage to make torque. It's best to run the stator as cool as possible, but that's more of a measure of the amount of copper you use.

We will see...

The LaunchPoint motor claims 8 hp and has about the same dimensions, but I think they use more magnets than I'll be using. (they are long and thin while I'll be using cubes)

"Success" will be if I input 1000 watts and can get 900 watts or better of actual rear wheel power.

What would be considered "Extra Credit" is if the Halbach Disc Motor can produce moped levels of power (up to 3 hp) and not overheat. I'm not expecting the "Extra Credit" level, but it would be nice.

 

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Cold Nights, Short Days

It wasn't until 1pm that I was able to start working on the disc today because the morning started off at 28 degrees. By 3pm the sun begins to set and so that's my signal to stop. (5pm and it's completely dark)

A better side view... the groove is forming:

...and back onto the drill I trimmed it down a little. Still will need to trim it some more and the other side needs to be created:

Tomorrow is the last day before another cold spell. This might really be "it" until spring. (however the weather in the midwest is unpredictable... you never know when you might get a warm spell even for just a day or two)

 

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Groovy

...it definitely has a groove now.

Ran out of time, but will spin it later. It can be cold for things like sanding by spinning the disc.

 

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Winter has arrived... so don't hold your breath on this project getting done any time soon. I'm storing the fiberglass resin indoors so that if there is a sunny day that I could possibly do some work. However, the forecast isn't showing any warmth for at least a week. It has to be at least 50 degrees to get the fiberglass to cure without problems because of excessive cataylst usage. (it's in the 20's at night and the 40's during the day)

 

[AussieJester]

.............................good too see some progress ...

KiM

 

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If At First You Don't Succeed...

Eventually I do get there... every attempt can't be perfect... and it shouldn't be that way. But in the end I always am successful. The rewinding ended with "success" in that the last motor is still running and it has 750 miles on it so far.

Ironically what you call "failure" is with motors that set all my speed records.

Reliability is the issue... excessive performance can mean low reliability...

Go fast... blow up fast...

 

[safe]

Alignment Seems Okay

The alignment for the chain seems okay. Maybe one more washer to space the disc a little more inward and it's just right.

Many are sure to be skeptical that this is possible... but if the CSIRO example is valid, that 97% efficiency is attainable.... then I'm on the "right track" towards the goal of the "perfect race motor".

No other technology is capable of achieving this to my knowledge.

The Halbach motor will be (whether I succeed or not) the future for high performance... it pretty much has to be.

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Comparisions:

Brushed Motor - 78% * (Geardown) 95% * (Final Drive Chain) 95% = 70% (best) ~60% (average)

Brushless Motor - 92% * (Geardown) 95% * (Final Drive Chain) 95% = 83% (best) ~75% (average)

Halbach Disc Motor - 95% = 95% (best) ~85% (average)

I'm not including the hub motors because they weigh too much, otherwise they do okay as far as performance. (too much iron is their problem) So far the Halbach disc I'm making is already rigid and strong with only a few layers of fiberglass and it doesn't weigh very much either. There are no heating issues to deal with, so as long as the strength is there it should be fine.

 

[AussieJester]

Go fast... blow up fast...

Hope the acceleration is a little crisper on this than your road bike
Are you expecting it too be? you think it could get around 8ish for the
100 meter 0-to go run? Best of luck anywayz mate
i havent been able to do alot on mine my legs have been playing
up extremely bad last week think the onset of hot weather triggers it...

Good work on the glassing thus far too...

KiM

EDIT: would look trick Safe if you got some carbon fiber and laid it on as the last layer to mate 'carbon fiber' gives a "racey look" to things
wouldnt do alot for the strength in this instance but the look Safe the look ;-)