(Non Hub ~ Hub) hybrid idea

[TPA]

Looking at the geared hub motors inner workings, I've had this idea running around in my head. I finally put it to ProE and thought I'd share it in the event anyone wanted to pursue it.

I no longer have the cad files, but they were not accurate enough for production purposes anyway.

Refer to the picture in the second post:

The entire orange section is the stationary axle/carrier.

The red part rides on needle bearings, connects to the input (freewheel) cog, and mounts the sun gear.

Bearings again (represented in yellow) mount on the outer surface of the red part to support the cover.

The planet gears only rotate in place. They do not translate around the axle.

This planetary arrangement yields the greatest ratio possible for simple epicyclic gearing, and can probably get to 10:1 without a lot of difficulty. If some steel components are incorporated, it could probably be made to withstand some serious wattage without the need for external intermediate reductions.

that means a direct connection from motor to hub, which would free up much space.

 

[TPA]

pic....

 

[amberwolf]

Unless I am misunderstanding, this is essentially like any of the geared hub motors (like my Fusin)?

I'm sure I must be missing something.

 

[mwkeefer]

Think fixed position CVT style coupling, flatten it a bit and whalla you have what our friend is communication (I think)... in essence the logic is sound (and already used in many devices) but the reduction wouldn't be the awesome part... the additional efficiency would be the real benefit (done right).

-Mike

PS: Please correct me if I mis-understood your CAD and intent

 

[TylerDurden]

He's putting the major reduction stage inside the hub.

External motor goes wherever you like, driving a typical cogset on the hub's input collar.

Downside: high chain speeds.

 

[mwkeefer]

TD - Thanks for the clarification, somehow I missed the input shaft part (tired).
-Mike

 

[TPA]

Unless I am misunderstanding, this is essentially like any of the geared hub motors (like my Fusin)?

I'm sure I must be missing something.

pretty much...except I think that in hub motors, the carrier turns and the sun is stationary, which gives less reduction...but I could be wrong.

in this arrangement the motor is taken outside the hub.

I liked the idea of mounting the motor on the rear axle like the Izip did, except that these rc motors are such high speeds that they need more reduction. You could make the ring gear as large as you are willing to make the hub. The ratio is -R/C (r=ring, s=sun)

Plus, rc motors are much higher quality and come in more flavors and varieties.

Another downside is that input rotation is in the opposite rotation direction than the output rotation. You would need to pedal in reverse which would likely turn some heads.

 

[TPA]

He's putting the major reduction stage inside the hub.

External motor goes wherever you like, driving a typical cogset on the hub's input collar.

Downside: high chain speeds.

Yes!, and only the motor, all by itself, need be mounted.

If you drove the left side, you could use a belt.

 

[amberwolf]

except I think that in hub motors, the carrier turns and the sun is stationary, which gives less reduction...but I could be wrong.

At least in my Fusin, the sun turns and carrier stationary:
http://www.endless-sphere.com/forums/viewtopic.php?p=287529#p287529
video is in that post.

I have no idea how to tell what gives more reduction; I do know that some Matex planetary modules I have (Currie replacements I think, from All Electronics) have either a 4:1 or a 4.5:1 depending on whether you take the output off the carrier or the ring, with input at sun. But I don't remember which way gets which reduction.

in this arrangement the motor is taken outside the hub.

That's the part I missed.

Basically to do this the Amberwolf Wayâ„¢ you could take any old geared hub motor that already has the ratio you want, and input from the RC motor into what had been the rotor, which will spin the sun. Then take the output off the spoke flanges.

If you wanted to use the assembly (minus motor) as the actual wheel hub as intended, then it'd need to have the input side bearing replaced with one large enough to allow a motor shaft (or jackshaft) to enter the system to drive the sun via whatever means (gear teeth directly from shaft to sun would be easiest to manage but maybe not to fabricate). Since it would just be a finger entering the bearing's ID, there would still be a spacer/support C-ring around the rest of the axle's circumference to allow that side cover to still rest on a solid surface--just like if you were doing this for larger phase wires than will fit inside an axle.

Another downside is that input rotation is in the opposite rotation direction than the output rotation. You would need to pedal in reverse which would likely turn some heads.

No, you just spin the motor the other way.

 

[Miles]

This planetary arrangement yields the greatest ratio possible for simple epicyclic gearing, and can probably get to 10:1 without a lot of difficulty.

If the planet carrier is locked, it's not epicyclic. The greatest reduction ratio (for a given set) is with locked ring gear, sun gear input, planet carrier output (R/S + 1) - output direction is the same as input direction. It wouldn't give much of an advantage in this case, though....