Oil cooling your hub- NOT snake oil!

[richdeloup]

A dash of white rum in the vent hole and 'voila' a refreshing drink, shaken not stirred at the end of your ride 8)

 

[Stevil_Knevil]

Thanks rich, I needed that

 

[pictsidhe]

I read through until someone started promoting glycerine, then it got too much...

No, just no! Glycerine is hygroscopic, you absolutely do not want anything hygroscopic inside your motor.

I haven't seen any reasonable vents yet. You must have a well vented hub or there will be be pressure fluctuations. Some inch long radial tubes as close to the axle as you can get seem optimum, at least 4 1/8" ID ones, could need many more if you are a killerwatt junkie. Shield the bearing areas from splashed/dripped oil. A riveted bit of flashing could probably work wonders. Make it's hole bigger than the od of the bearing, it may fill, having it's inner hole lower than the bearing will help. Arrange wiring so that oil does not run down it. A simple zip tie makes a great drip point. Oil will be everywhere, try to make it easy for it go where you want it (down), hard to reach things like bearing seals.

ATF seems like an obvious oil, mineral oil too. Haven't seen shock oil mentioned. That can be had even thinner than atf and has anti foam additives. You do not want too much oil in there, just enough to partially dip the stator windings. If I was doing this, I'd set up a temporary plastic sight tube from a rim fill/drain plug to one of the multiple vents, spin the motor and check the level was about right.

 

[spinningmagnets]

The Rad Rover fatbike on Indigogo is using a Hengtai rear geared hubmotor, and the retailer is oil-cooling the hubmotors. We''ll have to keep an eye on them to see how it goes.

 

[The Stig]

So wait, the Retailer? ...is taking the rad rover w/ greased hub motors and filling them with oil?

 

[spinningmagnets]

I was told that they will all have oil-cooling. Only time will tell if that's true, and if it works well for them (no leaks, happy customers, etc)

 

[crossbreak]

MagicPie 2 with Total Isovoltine 2

 

[crossbreak]

The Rad Rover fatbike on Indigogo is using a Hengtai rear geared hubmotor, and the retailer is oil-cooling the hubmotors. We''ll have to keep an eye on them to see how it goes.

I used this http://endless-sphere.com/forums/viewtopic.php?f=30&t=53939 motor for about a year in my commuter. It has drawback like large Rm and soft axle (i broke it twice)
But is is oil cooled and never lost a single drop during last the year

 

[Malloot]

Wouldn't the coolest (pun intended) way of doing this be using a refrigerant, make it about a quarter full with a refrigerant that evaporates at around 20 degrees Celsius. That way it will take allot of heat from the stator when evaporating and will then slowly condensate on the shell. This would probably give a much higher conduction of heat then a oil would give. No idea if a non conducting refrigerant exists but will try to figure that out.

 

[spinningmagnets]

I am fairly certain that the motor you linked to is what Zelena Vozila is selling as their small 800W unit. Steel helical gears, oil-filled. Sooner or later someone with a Rad Rover will take it apart and see if its the same, or a different supplier.

 

[spinningmagnets]

Cross-post from crossbreak, here:

"Super Commuter: 6T MAC 48V/120A Kelly in a 26" rim"
http://endless-sphere.com/forums/viewtopic.php?f=6&t=67825

Motor: 6T upgrade MAC from cellman
adding oil cooling to the hub:
17x26x7 seal rings
engine sealant
90ml of shell diala s2 insulator oil

small update about oil cooling. the shaft seals are tight, the side covers are tight, but i did not manage to completely seal the phase wires. There are always a few drops getting out.

I'll try using very thin silicone for sealing the shaft next. The used oil is Total Isovoltine 2 insulating oil. Very thin. Still eats about 150W more at 60kph now at no load :/. But Temperatures are very low now. Amazing how much effect this has. 3kW continous input power are not a problem anymore. I never reached more than 90°C after this mod.

Oil volume was ~110ml

The oil cooling is no experiment. It was planned in the first place, but I wanted to test how much difference this does, so I drove around without oil for some days. Shell Diala S2 oil was exactly designed for such purposes

As efficiency is quite low when climbing 15%+ hills, I think about adding a BBS02 750W middrive to help the MAC a bit on steep hills.

a bit disappointing but good for a commuter. I have 3kkm on the clock and the clutch still holds up...pulling 4kW peak.

the 6T does 50kph when the battery is almost empty (42V). The 8T would only do ~42kph with such little voltage of an empty battery. Too slow for town traffic.

I see no advantage in using the 8T. I had a 10T MAC at 74V before. Performance is the same. Both systems draw around 4000W.

But handling voltages >60V is not legal without special design and education in Europe. And I found no fan-less charger that is like the HLG240. The others i found are low quality and/or expensive. That's why i went for 48V (54V fully charged).

 

[macribs]

Posted by Justin_Le in this thread on the subject of sealing of the hub motor, read what he says below and make sure to watch the video as well.

On the subject of sealing, back when I was a lot more excited about oil fill we spent a lot of time looking into bearing isolators rather than physical shaft seals. This is a clever active technique where you have spinning baffles almost that keep deflecting water back out of the motor and keep deflecting the oil to stay in, and it does it with no additional drag(Large dia. rubber shaft seals do not spin very freely!) and it intrinsically allows for pressure equalization inside and outside the hub. Have a look:

http://www.inpro-seal.com/en_US/system- ... rotection/

[youtube]hET1JLpbTfM[/youtube]



They seemed like the ideal solution but unfortunately samples are $$$ and when we looked at getting production volume quotes of units sized for a hub motor application, the BOM cost of the bearing isolators was more than all other motor components combined.

 

[burningwings]

I am going to use soybean oil in my 3540 motor . Safeway vegetable oil. $5 for two quarts. This is the oil used in high power transformers. Tested all over the world . No toxic (food grade). In case it leaks will do no harm to pets or people ! Put some in the freezer it did not freeze solid. Had the consistency of Gasoline. Oter vegetable oils frooze hard.

 

[macribs]

Then you will have to check your garage for rodents :lol:

Just kidding, let us know how it works.

 

[Andytheswede]

I am going to use soybean oil in my 3540 motor . Safeway vegetable oil. $5 for two quarts. This is the oil used in high power transformers. Tested all over the world . No toxic (food grade). In case it leaks will do no harm to pets or people ! Put some in the freezer it did not freeze solid. Had the consistency of Gasoline. Oter vegetable oils frooze hard.

So how's it going?

 

[Andytheswede]

On another note:
I put 50ml of shimano hydraulic oil in my new Mac 8t.
First try was without sealing the motor and I had big leaks on the first run, most likely because the mac isnt exactly a piece of high precision work.
BUT, going wot 57v/40ah the motor stayed at 70C instead of the usual 90C after 10mins.

Question:
So have we reached a "final" consensus on what is the best stuff to use, when isolating the hubmotors prior oilcooling them?

 

[macribs]

This might work well for sealing the hub, it is industrial strength solution and seems like it would prevent leakage.
http://www.inpro-seal.com/en_US/technical-resources/multimedia/?ID=230

Seems the newest is to use ferrofluid, and those ferro parts keeps the oil sticking to the magnets and prevent leakage. Still no real data for ferrofluid but it seems we just might get that any day soon now. I recommend reading all of that thread as there are many ways to reduce heat.

https://endless-sphere.com/forums/viewtopic.php?f=2&t=48753&start=600

 

[Rodney64]

Has anyone used high temperature grease. Caltex EP2 works with temps up to 140 degrees Celsius.

 

[Andytheswede]

This might work well for sealing the hub, it is industrial strength solution and seems like it would prevent leakage.
http://www.inpro-seal.com/en_US/technical-resources/multimedia/?ID=230

And this has been discussed and tested successfully by several members of this forum?

 

[macribs]

This might work well for sealing the hub, it is industrial strength solution and seems like it would prevent leakage.
http://www.inpro-seal.com/en_US/technical-resources/multimedia/?ID=230

And this has been discussed and tested successfully by several members of this forum?

It has been discussed, but as far as I know it has not been tested by anyone here. Hence the wording, might work well. But as this is a solution created for the professional market I can really not see why it should not work. If their work was bogus I am sure they would be out of business rather then being more like the de facto supplier for sealing axles. But for that solution to work it will need some or alot of custom work. You will have to check with the manufacturer as this solution is yet to be documented and tested for hub motors.

Which is why I personally am leaning towards the ferrofluid solution. And oil based ferrosolution where the ferro particles stick to the magnets without leaving the oil behind.

 

[Punx0r]

IIRC Justin_le had a quote for those seals and they were something like $50 each. You would also need to modify the motor covers to suit.

 

[fellow]

My Q100H clutch is slipping in grease/ATF mix due too much of power applied (1kW+). Anyone using friction modifiers to help this, any raw data on how effective those are when used on our clutch systems?

*Some randomly choosed products to illustrate the matter

 

[Grizzl-E]

Wouldn't the coolest (pun intended) way of doing this be using a refrigerant, make it about a quarter full with a refrigerant that evaporates at around 20 degrees Celsius. That way it will take allot of heat from the stator when evaporating and will then slowly condensate on the shell. This would probably give a much higher conduction of heat then a oil would give. No idea if a non conducting refrigerant exists but will try to figure that out.

All refrigerant is non conducting. But you would have to build a motor that can handle high pressures. At least 300psi even with a low pressure refrigerant like r134a. You can't seal a motor shaft for that.

 

[Julez]

Hi guys,

I just glanced through the thread, but I probably oversaw this information:
Why do you prefer ATF to regular mineral oil? Is it because mineral oil is usually thicker and therefore would produce more drag?
If this was the case, have a look at Pentosin LHM+

http://www.pentosin.de/shop_produkt.php?c=&pid=697&vid=
Datasheet:
http://www.pentosin.de/flexxtrader/data/usf/Pentosin%20LHM_D.pdf

Pentosin LHM+

Kinematische Viskosität bei 100 °C mm²/s 6,2
Kinematische Viskosität bei 40 °C mm²/s 18,6
Kinematische Viskosität bei -40 °C mPa*s 1130

Without looking at this all too deeply, I believe that the viscosity roughly matches the one of typical ATF. But you do not have the agressiveness of ATF.
I used this stuff as hydraulic fluid on my Magura rim brakes, worked excellent.

 

[Joppo]

can i use semi synthetic motor oil (API SL/CF,ACEA A3/b3) for coolant in my motor?