A page for the collection of information concerning this project and the coordination of the build.
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
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
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?
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?
me: conceivably this should be more efficient than a standard motor
Bradley: yeah no friction
me: like a brushless motor
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
me: and would "levitate" on the magnetic fields
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
Bradley: yeah there are companies that sell magnets in quantities of 100-500
I think we would be looking at those
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)
me: I know that maglev trains' active component is a liquid nitrogen/helium cooled superconducting magnet on the track
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?
I'm going to chicago
I'll be back in the space next week
me: ok, I am going out of town Friday-Sunday
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
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