Hubless Motor

Hubless Motor

A page for the collection of information concerning this project and the coordination of the build.

Underlying Principles

This project is based on the same principles as a Mag-Lev train except wrapped into a circle: http://en.wikipedia.org/wiki/Hubless_wheel

Project Information

A really good write-up about Penn State Harrisburgh's project: http://www.recumbentjournal.com/news/gear/item/53-hubless-wheels-emerge-on-recumbent-trike.html

Project Discussion Transcript (the conversation that started it all 08/05/2010)

Bradley: how much experience do you have with linear motors?

me: do you mean motors that produce linear motion or actual linear motors?

Bradley: linear motors

me: I have read about them

D

that's like the maglev principle, right?

Bradley: kinda, the maglev works with the idea

the linear motor is the propulsion

same prinicpal as a rotary motor

but applied in a straight line

I plan to use it in a car hubless maglev design

as in the vehicle has no contact with the wheels and is held up my magnetic force

me: that sounds fascinating

Bradley: doesn't it

me: yes, it does

I would be willing to help

that sounds like a blast

Bradley: I hoped you say that

I want to build some prototypes and see how well it works

me: yeah, nice

Bradley: then throw it on to bike based power wheels

me: you'll have to explain the physical principles sometime in person

Bradley: think mag lev train

me: yeah, except with wheels

that don't touch

Bradley: the wheels take the place of the track

it's a vertically circular track if you will

me: haha, I just need to see some flux lines, that's all

ok, so the rotation mechanism is similar to that of a stepper motor?

so is the inside of the wheel lined with opposing magnetic fields?

Bradley: yeah

me: I wonder how that will hold up under load

Bradley: magnetic force is more powerful then gravity

but yeah I want to see that too

like can it handle 300 lbs

I think neodymium magnets can easily handle that

me: the car + a rider?

Bradley: yeah

me: conceivably this should be more efficient than a standard motor

Bradley: yeah no friction

me: like a brushless motor

Bradley: exactly

me: You know what, we may need to include some sort of rolling element to hold everything in place

Bradley: rolling element?

me: well, ideally the outer rim would never touch the inner rim

Bradley: yeah

me: and would "levitate" on the magnetic fields

Bradley: yes

me: I guess we'll find out as we prototype, but I was reading that tolerances have to be really tight

so if we needed to we could use Mag fields for propulsion and a bearing for suspension

Also: http://www.sparkfun.com/commerce/product_info.php?products_id=8643

Bradley: yeah there are companies that sell magnets in quantities of 100-500

I think we would be looking at those

me: true

Bradley: and a little flatter

me: so true

Bradley: but I'm going to look into engineering texts on maglev trains and such

I'm guessing they are using eletro magnets

or even super conductors

also there are low speed designs and high speed designs of linear motors

me: well, the control magnets have to be electro-magnets (obviously)

Bradley: yeah

me: I know that maglev trains' active component is a liquid nitrogen/helium cooled superconducting magnet on the track

Bradley: hmmm

LN2 on a power wheels

me: the level of coordination required for a bullet train's magnet systems is scary

haha, it depends on the superconductor, now you may be able to do it with liquid helium

they are getting closer and closer to room temperature

but they aren't there yet

I studied this in Materials Science

Bradley: closest I got was physics 2 and parts of quantum mechanics

me: close enough

anyway, I don't know if we can sustain electromagnets on low power

for the levitation part

Bradley: oh and lots of empirical science in highschool engineering

I need to study magnetism again

do they require high voltage?

me: not necessarily

Bradley: lots of current?

me: the magnetic field is proportional to the current

I just had a thought about the positioning of the levitation magnets

for some reason, I am thinking we'll need an odd number of magnets on the outer rim and an even on the inner rim

so there's not really a low equilibrium position

are you going to be at the space tonight?

Bradley: nope

I'm going to chicago

I'll be back in the space next week

me: ok, I am going out of town Friday-Sunday

we'll coordinate

Bradley: ok

me: I don't know if you read this article, it looks very good: http://www.recumbentjournal.com/news/gear/item/53-hubless-wheels-emerge-on-recumbent- trike.html

Oooh! We can implement a sort of regenerative braking (maybe)

do we have a wiki-space for this project?

Bradley: not yet

go ahead and make one

me: will do

Bradley: though I am curious as to what kind of magnets they used.

I'm assuming they used those cheap magnet strips

me: the article says it uses magnetic strips

but it doesn't state what kind or what strength

Bradley: yeah, that makes my mind think craft store supply magnets that come in rolls

I'm assuming the bulk of their cost came from the fact they used high grade aluminum

and the machining on those hubs looks professionally done on a lathe

or a water jet cutter

I'm thinking the heavy duty ones will work

me: I wonder if we could embed square magnets into the frame of the wheel with good results

it seems to me that most magnetic strips are rather weak

Bradley: I was thinking of gluing them for a working protype

me: right

Bradley: and using kids bike wheels

we can remove the spokes and hub once we are satisfied that it will work

me: I am going to copy and paste this conversation into the wiki for future reference