Good! Someone finally oil cooled a hubbie!! HS3540

[John in CR]

Very many folks have burned coils, very few have demagnetized magnets, according to the reports we see on the sphere.

No, they just cook them enough for the epoxy to weaken. Burning up windings while being oblivious to what the motor is telling them is evidence of nothing. It's definitely not a badge of honor like many treat it.

[parabellum]

Considering, smallest gap between stator and cover is to magnets, most of the heat to cover goes over the magnets, so the temperature on them is way higher then cover it self. Passing the heat to case directly, over the oil can substantially lower temperature on the magnets. I am definitively in for trying this method on my burned Hx. I already wound 8 toots (out of 51 ).

[Tench]

That was my thought too, the surface temp of the magnets must be much higher than the case temps as they are closest to the radiating heat, with the oil in there the surface temp of the magnets will be way lower, only multiple probes and testing could give us the facts but i am sure this would be the case. Prolonged exposure of the epoxy to the oil could be an issue though?

[bigmoose]

Prolonged exposure of the epoxy to the oil could be an issue though?

No, not with the right epoxy. I helped spec the epoxy for a gent here who repaired a motorcycle alternator where the magnets were epoxied to a steel ring, and bathed in hot engine oil...

[parabellum]

Prolonged exposure of the epoxy to the oil could be an issue though?

In most motorcycles I took apart generator and ignition windings run in oil, not summered but wet. Maybe some specific epoxy?

[Erogo]

The right epoxy, and the right oil. The oilbath fella tested his oil before sticking it in his motor. Nothing if not thorough, that fella.

[John in CR]

Maybe it's my imagination or maybe the spoke sink enough heat away to make a difference, but the magnet backing ring where I feel it between the spoke flanges is always a bit cooler than the side cover right where it is closest to the end winds. I don't believe through the magnets is the primary pathway for the heat. Instead I believe it's through the air that flows over the end copper and through the aluminum covers.

I see a lot more risk than benefit, and if you're running extreme power and getting the copper that hot, then you better get some fluid flowing through the motor and rejecting the heat outside, because your 80° magnets will get roasted...I guess in this case deep fried. That's assuming the motor assembly shop that used the cheap magnet wire decided to spring for good high temp epoxy....Yeah right, especially when the fanboy club's favorite went for the hall sensors that cost something like 2 cents each.

I'll leave that one for you guys. For me it's easy to stay within my motor's limits. For more I'll go with flowing ambient air through the motor, which works fine, since the only ventilated motor I have in use never gets past barely warm. The next step higher, if I ever get a controller up to the task, is to get crazy with active ventilation which my non-rotating drum brake covers permit. Last but not least would be adding a mister to the mix.

[mwkeefer]

I'm pretty sure MWKeefer experimented with oil bath cooling several years ago.

Did that guy have one of the sensorless motors, because that's my problem with the approach. ie I don't want the turbulent flow of a liquid coming near my hall sensor wires, since it would seem to guarantee a failure.

I did and in fact Still have one motor I haven't built up into a wheel and one that runs on a 20" folder - I push 18S @ 60A maximum for 4300w+ or roughly 5.8hp peaks through a 6 FET Lyen with IRFB4110s and with approx. 12" of phase line between the controller and the hub... while the oil added a bit of weight, I really ran the sucker hard for a long while it was my primary commuter (about 4 months my dad was in the hospital about 18 months ago) so figure I was hitting 40mph in 2.3 seconds (laying out over the bars) and maintaining that up RT 352 for a few miles to the hospital from the train station..

Internal gearing on my design was 8:1 and it really does rip but it's heavier than I would like (hardened steel gears add to that), compound that with this tidbit, getting anything made in china to your provided specs (even when sending CAM / CAD files) is like pulling teeth imho, so the motors I have aren't even up to my spec (no magnet to catch debris, added visual window to the side cover which just adds potential point of leakage)... even still, properly filled with 10w40 the thermal impact is notable... It not only reduces the internal gear friction and reduces the heat potential on a mechanical level but it provides a fairly competent viscous thermal transfer between the in-runner within all geared hubs and the outer shell of the hubs themselves.

So to be honest, I'm still looking for pics of these "new" hubs to determine if they are a design of my origin finally made it here or if they are refined a bit and worth an investment..

Hope that helps to clarify since all the links to my old postings (and many others) are MIA

Regards,
Mike

[Toorbough ULL-Zeveigh]

the return of keef makes3.
will xman step up to make it a grand slam?

it's like the beginning to the magnificent7.

[gogo]

the return of keef makes3.
will xman step up to make it a grand slam?

it's like the beginning to the magnificent7.

[John in CR]

A geared hub is a different animal that is far more thermally restricted, and the oil bath takes heat away from the motor shell, which would be a lot like taking a hose to a DD hubbie and cooling it from the outside, which of course would help. MWKeefer also wanted the oil for gears, and it's more sinking heat away from the magnet backing ring than sending heat more directly from the stator to the magnets, which would be the case with a DD.

I'll just stick with being from Missouri on this one. I'll have a bike at the 2012 Pikes Peak race that is air cooled, so that's a perfect chance for the believers to prove that an oil bath is better.

[mwkeefer]

the return of keef makes3.
will xman step up to make it a grand slam?

it's like the beginning to the magnificent7.

Perfect P

[def215]

Mwkeefer! Good to see you back around. Haven't seen you in a while around here.

[mwkeefer]

Sup def?

[def215]

Sup def?

nothing much. i shouldve called you during the summer to meet up because i was working in the KOP area all summer but i totally ended up forgetting

[MikeB]

There is an Engineering outfit, in Pa. that sells an 8 KW hubmotor that is oil cooled. Zehrbach or something like that.

You have to be special schooled to be able to buy them

I don't know about being special schooled, you can buy those 8kw oil-filled hub motors already installed in a scooter here: http://zelectricvehicle.com/

He's been selling them for a couple years, so it's not exactly new.

[Miles]

He's been selling them for a couple years, so it's not exactly new.

The Rabbit tool hub from ten years ago is the earliest example of an oil-cooled hub that I know of: http://www.rabbittool.com/frames/frelcwhl.html

[Hillhater]

, you can buy those 8kw oil-filled hub motors already installed in a scooter here: http://zelectricvehicle.com/

He's been selling them for a couple years, so it's not exactly new.

hmm, ? ... thats quite an impressive machine, and up to 9.2kW (continuous)..183ftlb torque !
6kWhr bat. ....
80 mph ..100ml range.... under $8k
.... you could spend that much just building a 6.0 kWhr battery !

[Gordo]

if your going though all the trouble to liquid nitrogen cool, may as well use a high temperature superconducting coil too ...mike

mike our lab, in the development of a superconducting motor to run in LH2, used ultra pure copper in LN2 as a step along the way. The UP-Cu at LN2 temperatures was amazingly successful as the Cu resistance at LN2 temperature is about 14% of room temperature, IIRC. So you gain to the first order 86% of superconducting performance by cooling the UP-Cu to LN2 temps.

bigmoose,
What problems with brittleness at these temperatures? You bump something and it snaps off like glass stemware.

[bigmoose]

The ultrapure copper was run in a vertical cryostat and had no problems. Of course we did not beat the snot out of it physically while characterizing it's performance. Google cryogenic motor and you will find the papers and reports that are on the web.

[deVries]

Prolonged exposure of the epoxy to the oil could be an issue though?

No, not with the right epoxy. I helped spec the epoxy for a gent here who repaired a motorcycle alternator where the magnets were epoxied to a steel ring, and bathed in hot engine oil...

Can you tell us what epoxy that is or the type to get

Thanks!

[bigmoose]

Here is my bonding epoxy thread:
http://endless-sphere.com/forums/viewtopic.php?f=16&t=27270&p=394183

[Teh Stork]

These results are really nice. I plan on running a maximum of 6,5kW through my HS3540. I had planned on drilling holes and possibly having a pressurized water mist sprayer, but this seems like a better solution. Then again, looking at his video of him riding - accelleration and deceleration in city landscape over and over, dumping 3kW into the motor at every intersection. It's not a surprise he toasted it. I'll definitely run it under conditions far more forgiving than he did. I plan on running fast tho, 70 kmh.

Isn't it possible to program the controller, or bootstrap a uC, to plot current regulation as a function of speed? As long as you don't exceed max power out (witch depends of speed*torque), you should have great efficiency and minimal heating. Everything above this will be heat? So feeding the motor 2kW should only generate a measly 240 watts of heat (using 88% motor efficiency). Am I missing something?

[parabellum]

Have filled Mxus DD sensor hub with Motul SAE 0W40 oil. 150ml
Did not got anything thinner in stores around, so I was choosing between 3in1 and 0W40. For next one will try to find thin spindle oil.

Normally whenever I get home hub covers stars heating first, going up 10- 20C then cooling down.
As original at 60V 24C and up
freewheeling 1.2A

I sealed sensors and covers with black silicone.
Edit: I also covered the windings with varnish for windings 2 times afterwards. That stuff is thinner based, so silicone does not like it.

After oil fill 60V
24C- 2.7A
50C- 1.7A
After oil filling, the temperature was 50C on arrival and started drooping from start on.

Other improvements: pulled 3x 1.2mm magnet wire trough axle for every phase, for~AWG 12, they was AWG16 before.
Fail: Forgot to pull temp sensor lines

Some porn.

[Burtie]

Have filled Mxus DD sensor hub with Motul SAE 0W40 oil. 150ml

Hi parabellum, any updates on how this is working out with use ?


This oil cooling sounds like a good idea to me, so I had a crack at it too.
I also modified an MXUS DD hub as follows:

1) Added a temperature sensor in the windings near the top of the motor ( away from the oil pool )

2) used silicone gasket sealent to fix the covers and seal the axle slot.

3) Added a threaded filler hole in the side cover for the oil.

4) Filled the hub to various levels with mineral ATF (Dexron II) and measured the no-load current @ 36v

Temperature sensor.jpg (232.27 KiB) Viewed 910 times

Sealant.jpg (146.21 KiB) Viewed 910 times

Fill level at 400ml.jpg (194.06 KiB) Viewed 910 times

At 400ml fill, the oil level is just below the axle, where the filler hole is in the above photo, (you can just see the red coloured oil inside the hub).
With this much oil, the motor makes a satifying, just audible ,sort of sloshing noise when it is spun up.


No oil, no load current = 1.05 A
150 ml oil @ 18 degrees C = 2.0A
200 ml oil = 2.0A
250 ml oil = 2.1A
300 ml oil = 2.15A
400 ml oil = 2.15A

I will leave the oil level @ 400ml and install it on my bike to test the thermal effects.
The bike currently has an identical motor fitted, including a temp sensor (just no oil), so the comparison will be interesting.

Burtie
edit: corrected reference to Dexron II