~Free cooling fins for non-hub motor

[McDesign]

I've been reading here, and it seems that a consistant problem with the small brushed motors is overheating.

I work with thermal management in my real life, so here's what I'm going to try. First, I'll put the motors in the airstream (on top of the front wheels, in this specific application) - but still, there's darned little surface area available for convective heat transfer to the ambient air - so how cheaply and best to add "extended surface" (radiator fins (though a car radiator doesn't really "radiate"; it's a heat exchanger))?

An axial fan might be nice, but it takes power to run, and its airflow is perpendicular to the nice cooling airflow from the motion of the moving vehicle

Not long ago, I learned to make signal lamp and fan shroud bezels with just a hammer - bend a long piece of ~1/2 X 1/2" angle from .060" aluminum, and keep hitting one flange as it lies on an anvil or a vice (I do have a shrinker and stretcher now, but they're just faster, not better)



View attachment 3



So now, make some similar rings, and tie-wrap them to the motor (drill some clearance holes in the mounting foot for the tie-wraps to pass through), using some conductive grease between the steel motor case and the fins -



I think I may try one with and one without on the first trike, thermocouple both, and see what surface temp differences I see.

Forrest

 

[olaf-lampe]

Nice idea, but be sure you don't create imbalances. At 10k rpm the tie-wraps will have a hard time too.
As you sure know, there's also conductive compound.

Keep us updated
-Olaf

 

[McDesign]

Hey - just reading some of your posts - no - this is a stationary (non-hub) motor - though, balanced, it might work on a hub motor - with SS safety tie-wire for the clamping.

Forrest

 

[jag]

Thanks for your excellent description. I had been wondering how to make cooling fins like this for some time. Should work really well on inrunners as they would be directly cooling the windings. Will probably also be good to cool the magnets on DD hub motors. Rotation speed is so low that a the very small weigth imbalance is not an issue. (this is less than the imbalance from the inner tube valve anyway I would guess).

Where does one obtain malleable aluminium sheets suitable for this?

A lazy man's option would be to see if it is possible to buy pre-made flanges with a diametre close to the particular motor (e.g. 3" for the Astro and similar inrunners, 8" for 9C hubs).

 

[McDesign]

I use scraps of "half-hard" (H-14) 16-gauge 3003 aluminum sheet - pretty standard and common - it suprised me how easily it formed into that tight curve - it's like a 1" radius - with just a ball pein hammer and forty billion whacks!

Forrest