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All-In-One Motor

Posted: Jan 19 2019 4:24pm
by gman959
Hey Everyone,

I need some help sourcing a motor for our senior project. Im struggling to find a motor that doesn't have the wires coming out of the axel. We are trying to make an all in one rear bike hub with all the components inside the wheel. Our current issue is that most commonly available motors have the coils on the stator instead of the rotor like we need. Is this even a thing or is it a pipe dream? Thanks everyone!

Re: All-In-One Motor

Posted: Jan 19 2019 9:05pm
by e-beach
Hi gman959, welcome to ES!

I am not sure why wires a bother. All motors have wires coming out of them. If you don't like brush-less motors you can always try a brushed motor.

Tell us a bit more of what you are thinking about when you say everything in the motor.

:D :bolt:

Re: All-In-One Motor

Posted: Jan 19 2019 9:43pm
by mark5
The iMortor front wheel hub motor has everything in the wheel but otherwise isn't what you want, is it?

At 3:09 in the video is where it's opened up.

Brushless Electric Bike Kit iMortor - Teardown + High Power Mod by Marco Reps
https://youtu.be/k9-8tPqvDs4?t=3m9s

Re: All-In-One Motor

Posted: Jan 19 2019 10:45pm
by amberwolf
gman959 wrote:
Jan 19 2019 4:24pm
We are trying to make an all in one rear bike hub with all the components inside the wheel.
If you really want to put everything in the motor (batteries, controller) you just need a bigger space inside. You could look for a used BionX D series motor, which has a fair bit of space inside, and use a very tiny controller and very small capacity battery. Look around the forum for titles with BionX and there are a few threads that have some internal pictures of it.

However...it gets hot inside the motor, especially with the controller in there, so this will degrade the batteries faster than normal. As long as power is kept low, then this will help reduce the waste heat inside, but there will always be some.


There are also motors that already ahve the controller built in, like the GoldenMotor Magic Pie series. But there's not much space left for anything else in there.

Another option is using a completely separate hub in the other wheel to hold the battery, like the TidalForce bikes did. You could take a second hubmotor and cut out the entire stator except for the (usually six) supports on the axle, leaving only those and the axle in the middle with bearing support for the side covers, and even take the magnets off the rotor. Then build a frame for the battery that fixes to the old stator supports that fits inside the rotor and covers. You'd get a lot more space inside (though still not very much) for batteries that way. You could make new covers that extend the space available, if they still fit within the fork or frame of the bike.
Our current issue is that most commonly available motors have the coils on the stator instead of the rotor like we need.
All brushless motors (which are what is used these days for hubmotors) will have the coils on the stator. If they didn't, the wires would get all twisted up as the rotor spun, and you wouldn't get very far. ;)

If you used brushes instead of wires to get power to the coils, then it woudln't be a brushelss motor, but it can be done. Is just wasteful of power and makes more heat from the brush arcing. That arcing can also cause FET failures in the brushless controller sometimes.



You could use an old brushed hubmotor, but it will generate more heat inside, and I don't know of any old brushed hubs that had any free space inside.

Re: All-In-One Motor

Posted: Jan 19 2019 10:55pm
by amberwolf
Another option is to build your own large hub with lots of room inside, with a plate mounted to the axle for bolting motor batteries and controller to.

Then put teeth on the inside of the rotor (spoke flange), and use a small motor with matching teeth on it's shaft to drive the hub from inside. Might need a secondary "transfer gear" like the planets in a geared hubmotor would have.

There's probably a number of ways to completely DIY the project.

Re: All-In-One Motor

Posted: Jan 19 2019 11:03pm
by spinningmagnets
There are plenty of motors that use a solid axle with the wires coming out the side of the motor. I can see where that would make modifying the insides of the motor space easier.

I think what you described at one point was an outrunner. An inrunner and outrunner both have a rotor and [stationary] stator. One has the stator around the outer edge, and one has it in the center

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Re: All-In-One Motor

Posted: Jan 22 2019 3:49pm
by gman959
What we are really trying to do is something like the Copenhagen Wheel or the Electron Wheel. Our issue is that most ebike motors on the market have the wires coming out of the stationary (with respect to the bike frame) axel. Like mentioned earlier, if the wires came out of the axel they would eventually need to go back inside the wheel to be connected to the other components but since those are spinning it would obviously becoming twisted almost instantly. Thats why we would need the axel to have the magnets and the "casing" have the windings. I hope this makes some more sense. Id be happy to draw some pictures if need be. Also thanks for the help everyone!

Re: All-In-One Motor

Posted: Jan 22 2019 7:40pm
by e-beach
Pictures would help me out because I am still unsure of your application needs. Even self contained e-bike motor/wheel systems have a fixed axle.

Please, draw us some pictures.

:D :bolt:

Re: All-In-One Motor

Posted: Jan 22 2019 8:24pm
by neptronix
There's some fully contained battery + controller + motor in a case solutions that use some kind of torque sensor like the hymotion... but they suck because they are heavy ( or extremely low range ), have low power ( because all the components share the same thermal space ), and have really poor means of sensing pedal input.

History has shown this design to also be very unreliable, but companies keep trying and failing regardless. Even just having the controller and motor in one package has turned out to be a bad idea for pretty much everyone who has done it.

I rode a few at interbike and was about as unimpressed as i thought i would be.

A standard ebike hub motor is so much less expensive, far easier to service, and can have an actually decent range and output.

Re: All-In-One Motor

Posted: Jan 22 2019 8:34pm
by neptronix
gman959 wrote:
Jan 22 2019 3:49pm
Like mentioned earlier, if the wires came out of the axel they would eventually need to go back inside the wheel to be connected to the other components but since those are spinning it would obviously becoming twisted almost instantly. Thats why we would need the axel to have the magnets and the "casing" have the windings. I hope this makes some more sense. Id be happy to draw some pictures if need be. Also thanks for the help everyone!
You must have some kind of misconception of how regular hub motors are built.

The case spins, and the wires are stationary. The axle does not spin because it has a flat section holding it into the dropout.

If you are dealing with a bike with a completely round axle interface, then you need a motor that fits that interface, and there are a couple of them out there.

Most hub motor builds here are done with a bike that has slotted dropouts though. Because hub motors are designed with that in mind.

Re: All-In-One Motor

Posted: Jan 22 2019 9:07pm
by amberwolf
gman959 wrote:
Jan 22 2019 3:49pm
Our issue is that most ebike motors on the market have the wires coming out of the stationary (with respect to the bike frame) axel. Like mentioned earlier, if the wires came out of the axel they would eventually need to go back inside the wheel to be connected to the other components but since those are spinning it would obviously becoming twisted almost instantly.
:? I don't understand...or rather, I don't think you understand how these are built.

You would simply not run the wires out the axle in the first place. (or rather, pull them back inside when you have it open to mount the other stuff inside).

None of the parts inside the motor are spinning.

Only the casing of teh motor (with the magnets) is spinning.
Thats why we would need the axel to have the magnets and the "casing" have the windings.
Won't work, for a brushless motor. Then you'll REALLY have twisted up wires.


I think you really should look around at some of the various "disassembly" threads so you can see how things actually work inside these motors, because it sounds like you've never had one in your hands to look at. (if you did, it'd be fairly obvious how they are constructed, and what it would take to do what you want).

Again, look for the BionX threads for the D series motors, and the GoldenMotor MagicPie series motors, as those have the most space inside.

Or this thread:
https://endless-sphere.com/forums/viewt ... =4&t=98396
about a separate hubmotor, battery hub, and controller, but has pics inside the battery hub.

It's very simple, other than getting rid of the heat (or not creating as much of it in the first place), and getting batteries and controller small enough to fit inside the small space in there.