Stevil_Knevil said:
Which motor, John? Did you try it on both sides, or just the side you expected it to be drawn into?
It was the motor on my son's Clown Bike, call it an H40. It has one sided intake and exhaust out of both sides. If you mean did I try to make it intake at the ring of exhaust holes, no of course not, but I did put it near there to see if it could demonstrate the outflow of air that I could feel coming out, but it just made the smoke disappear. I did that 2 years ago, and did think about using a smoke bomb since fireworks are available down here. I nixed that after remembering how they stained the concrete when I was a kid, and I didn't want whatever those chemicals are on the inside of my motor in case it reacted with the plastic on the wiring or varnish on the windings.
Hubmonster isn't on a bike right now, so I could very easily put it in the vise, burn something to create smoke, and use my camera that can take videos (crappy but good enough capture this), figure out how to post a video, and show the motor sucking smoke in the intake. Since it has exhaust only out of the other side it might even capture that the smoke is coming out of the motor on the exhaust side.
I actually want to test intake at the top rpms anyway, because spinning the motor up on the bike, I stuck my hand carefully near the exhaust that's recessed in the rim on that motor to feel the flow. At moderate rpms I could clearly feel air blowing out, but it seemed to diminish as rpm neared no load speed. I couldn't tell if it was reduced flow or that the cover bolt heads or the raised ridges on the cover were creating enough turbulence that I just couldn't feel it anymore. I'd like to find out if it really was reduced flow, because I need to fix that to run at higher voltage. If true then I suspect it's from not enough intake area to support the higher flow of the higher rpm and as a fan it gets starved of air and stops blowing much air at all. If you've ever restricted the intake of a server blower to a point where the sound changes pitch and output flow drops drastically at the same time, then you understand my concern. The motor does get warmer on the highway, but never hot, so I haven't worried about it. The solution is more intake holes or enlarging those I already have, which means opening the motor, something I'm loathe to do if it means pulling the wire side cover, the intake side, because it would require redoing the motor harness.
I can easily pull the other side and magnet ring, so maybe I can get comfortable that I can blow out any AL shavings and just drill it while on the stator.
If it would really put the matter to rest once and for all, I'd go for it, but it won't, because of the valid point that the exterior influences are different spinning stationary vs rolling down the road. The simple fact that air has mass is already proof enough for me. For those who don't get that part, then powering a 360lb load 4 miles up a steep mountain road, riding hard enough to get 4% regen braking into the corners
going uphill, while consuming 160wh/mile, is a slam dunk as far a proof goes. Hell, Itchynackers ran hot up pikes peak with an oil cooled motor using far lower power, pedaling his ass off, in much colder ambient temperatures. Sure his covers have less surface area, but not 5 times less, and mine don't transfer any heat to speak of anyway, since they stay near ambient temp and heat transfer isn't possible without a temperature differential.
The heat doesn't go thru the covers. It's not stored in stator because hot air would rise out of it when we stopped at the top. Hubmonster is no more efficient than typical ebike hubbies, so it's not magic. If the ventilation approach doesn't work exactly in the common sense manner that I've explained a number of times, where does all that heat go? It can only go right out the exhaust vents with the centrifugal flow of air.
John
