bigger hub motor wires-Ground one phase to frame?

[4sken]

I haven't seen this done much at all or even talked about (Might be a lack of searching) But wouldn't it be possible to ground out an entire phase to the bike frame, letting you have bigger phase wires into the axle?

 

[amberwolf]

Why would you want to short one of the motor phases to the stator laminations?

If you're not sure what I mean by that, you might want to look at the typical hubmotor's construction.

 

[Punx0r]

IIRC it's do-able, but carries of the obvious risk of making your whole bike frame live. I'd guess none the electronics on a typical ebike would be using their casing as a ground, but if they did you'd have problems.

In reality, the size of hole that can take three cables isn't much greater than one that can take two...

 

[Triketech]

Bearing erosion will be a big problem.

 

[John in CR]

That's comparable to running your fuel line through the tires on a smoke belcher. The lams forming the iron core are generally not isolated from the axle, and it will short to the rotor via the bearings. Good try though as I haven't seen that idea come up on the forum....On to the next idea.

FWIW, motors with axles appropriately sized for safety considerations have sufficient space for phase wires. The problem is they don't fit into standard bicycle dropouts, so it's the connection to the bike that needs improvement, though room temperature superconductors is the dreams come true solution. For the weight weenies, instead a heavy solid rod for an axle, do what Farfle did and go to an even bigger diameter but hollow for strength and plenty of space for wires, coolant flow tubes, whatever.

 

[Punx0r]

I agree the stator would become live, but I don't see how that would be a problem? Unless you already had another phase shorted to it due to a winding insulation failure...

Bearing erosion is a good shout.

 

[John in CR]

I agree the stator would become live, but I don't see how that would be a problem

Don't controllers blow with just one phase shorted to the stator or does it take 2? What about eddy currents in the stator and rotor having a direct connection to one of the phases?

 

[4sken]

I don't understand how connecting one phase to the axle would cause a short condition... Path of least resistance would be from the bike frame, cross the axle onto the phase. Where would that short to?