Air Cooling my x5

[stew007]

I think motors can handle quite a bit of dirt and moisture, If we a look at what the RC car crowd give there motors, constant dirt and moisture, it never usually the cause of the demise of the motor,

Also, if you have the holes so water can escape just as easy as it can get in, then I think there is no worrys. The motor dries out very quickly. Also having a sealed motor, if water does get in, it may accumulate due to the sealed casing, I think I read of this occasional being a corrosion problem on the ebikes.ca site with the crys motors. Also I think dust is not really much a problem, after say 500 if the windings are getting dusty, they can be cleaned through the holes with some compressed air. Larger stones could be a problem if using the bike off road or through deep mud etc, but I have never had any stones bounce towards the hub, the tyres normally seem to eject stones away from the wheel. Also over heating of the motor is likely to cause damage over time, so the cooling outweighs the other risks I think but this is just the risk i'm willing to take, and now after running like this I would say for me the risk is extremely low of damaging the motor.

As someone else mentioned, the air scoops mounted over the holes would be a great idea, not only would they deflect stones, they would improve airflow, some suction, some compression, that would maximise the airflow

,

 

[Doctorbass]

What if you partially flooded the motor with oil, like Reid Welch does. When the motor is spinning all the oil would be around the outside and you could fill it just enough so that the surface of the oil would be touching the stator. At the moment it seems the only place the heat can escape the stator is through the axle, and a bit of convection between stator and casing. If oil was touching the outer surface of the stator that would be a much bigger area than the axle and there would probably be a lot of turbulence in that oil ---> better heat transfer.

The mod on the previous page looks good, very easy. Using oil would have the advantage of keeping water and dust out, although dust doesn't really matter.

This is an excellent cooling idea.. oil help to transfer heat better than air.. and many HV transfo yse it (llike mineral oil)..

But there is two important think to not forget about that:

First:every glue inside the motor will be affected! and the rotor magnet are fixed with glue !!!
what happen is that porrous metal absorb oil over the time and.... the aluminium inside the motor is porrous.

So about that i would worry to have one day some magnet that take off!

Secondly: at low speed the motor will endure that oil movement.. but at higher speed that will offer alot of restriction! and additionnal precious watt lost in additional heat...

than with this oil idea i would recommand to be carefull about that.

Doc

 

[vanilla ice]

The rubber sealed bearings are probably just a default, I wouldn't ascribe any significance to the fact RS type bearings are used. I'd run metal shielded with no hesitation. And hey if the swiss-cheesing does cause accelerated bearing wear.. bearings are cheap! BTW here's a fun little read on "sealed" bearings- http://www.sheldonbrown.com/brandt/sealed-bearings.html

What else do we need to be concerned about wearing from dust? The motor parts are pretty beefy arent they? Anyhoo pop some clip-in foam or mesh filters on the holes, anything bigger than dust should stay out. Like most things swiss-cheesing it is a trade off, IMO seems a very worthwhile trade from what stew had to say.. small risk for big return.

 

[curious]

What else do we need to be concerned about wearing from dust? The motor parts are pretty beefy arent they? Anyhoo pop some clip-in foam or mesh filters on the holes, anything bigger than dust should stay out. Like most things swiss-cheesing it is a trade off, IMO seems a very worthwhile trade from what stew had to say.. small risk for big return.

Remember, there are strong permanent magnets there. Anything ferrous in the dust/particles and it will get stuck there forever (unlike exposed disk brakes for example).

 

[curious]

What about antifreeze fill instead of oil ? Any chemists here ? Would it react less with internal glues ?
Or perhaps silicone oil ?

 

[steveo]

under what circumstanses would you need to do this to an X5 ?

when your bike goes stupied fast !! .. your draw higher consistant wattage through motor & controller .. as doc said .. motor heats faster then controller ..

cooler motor .. more power!!

-steveo

 

[The Stig]

What if you partially flooded the motor with oil, like Reid Welch does. When the motor is spinning all the oil would be around the outside and you could fill it just enough so that the surface of the oil would be touching the stator. At the moment it seems the only place the heat can escape the stator is through the axle, and a bit of convection between stator and casing. If oil was touching the outer surface of the stator that would be a much bigger area than the axle and there would probably be a lot of turbulence in that oil ---> better heat transfer.

The mod on the previous page looks good, very easy. Using oil would have the advantage of keeping water and dust out, although dust doesn't really matter.

This is an excellent cooling idea.. oil help to transfer heat better than air.. and many HV transfo yse it (llike mineral oil)..

But there is two important think to not forget about that:

First:every glue inside the motor will be affected! and the rotor magnet are fixed with glue !!!
what happen is that porrous metal absorb oil over the time and.... the aluminium inside the motor is porrous.

So about that i would worry to have one day some magnet that take off!

Secondly: at low speed the motor will endure that oil movement.. but at higher speed that will offer alot of restriction! and additionnal precious watt lost in additional heat...

than with this oil idea i would recommand to be carefull about that.

Doc

Did you check out the link? Reid has done this and it seems to work. Only its for lubrication and noise reduction in a geared Ezee hub.

I think the oil ruining the glue is a non-issue, at least it is with Reid's hub. I would hate to think gear oil can degrade the glue used in my motor. The glue cant be that bad.

And about loosing watts at high speed I think I need to show you a picture of what I mean by PARTIALLY filled. When the hub is rotating at high speed All the oil will be pushed out to where the magnets are. When the oil is pushed to the outside, there will be just enough of it to touch the outside of the stator, this should cause negligible friction losses to the oil. We cant be sure how much energy that would use up unless it is tested. In Rieds hub it didn't cost him any efficiency at all.

 

[Doctorbass]

Guys.. I absolutly need to share what happen to me since i drive up to 100A and 100V on my X5

With an average opower of 3000W and peak to 8600W many times from hard ride, my motor temp reach easylu 130 celsius and today again reached above 150... i mean 156 celsius.. and at that temp the motor have around HALF the acceleration from a totally cold motor (ambiant temp)

And my alarm temp sonsor beep often.. almost tonight with my last e-ride.

This is so important athan i planned and began to locate place with my GPS where there is some ventilation blower grid output from large building .. and i put my motor in the air flow and let it cool for few minutes.. to be able to enjoi the rest of the ride WOT.. otherwise i must lower the current to 20-30A at 100V..

Idea 1:
I am considering to find some powerfull RC motor with propeller that i will cary with me and plug it on my battery.. they are lightweight and blow alot of cfm!...

Idea 2:
Or i might find some tube to force air flow from the front of the ebike and to make them blow close to the motor.


Idea 3: drilling two holes ( one on each side cover) and to cary with me a littke comtresspr or high psi fan to purge the hot air of the inside of the motor from one hole to the other



Idea 4: watercoolig tubes...


Doc

 

[potatonet]

.... I think I said this already

project axle custom made that is HUGE (chromoly), drill right through the center about 1/6 the way through on both sides (enough to get inside the covers), run methanol liquid cooling with small radiator and high flow pump.

you can run the liquid cooling to finned coils inside the stator from outlets on each side of the axle. the center of the axle is solid.

If I were running 10kw thats what I would be doing. you could even super cool it which would be amazing

 

[solarbbq2003]

couple of ideas need to use the air inside to cool it, first idea was just drill large dia holes directly over where the windings lay, and glue aluminium finned heat sink over the holes, windings will pass very close to the hole and should stir up the air a bit, fins would have to be quite low, thinking of cpu type heatsinks.
Other idea a bit more hard to build, drill large holes, some over the windings, some in closer to the axle, join the holes with hollow aluminium tube but flattened out quite a lot, how to join the tube to the holes difficult.
the inner holes would have quite alot of room on the inside of the motor, might be able to put some sort of blades on the inside that brush very close past the tube, might set up some air circulation via the aluminium tube ( heat transfer via aluminium tube to air outside).

 

[stew007]

The oil cooling could work, but! you have to take into consideration the effect of the viscosity of the oil/coolant acting between the stator and the magnets as it is a tight gap, so it will act like a torque converter, like which joins your auto transmission to the engine of your car, which may reduce your efficiency, the faster you go, the more friction would be generated.

Also, Air, when it is enclosed acts as an excellent insulator, thats the reason why double glazing is so effective, and other insulations act to trap air in order to retain heat. So any form of cooling fins to act on a sealed air cavity will probably have little effect. The most effective way would be to remove the hot air from inside the casing. If the shaft was bored and joined with flexible tubing to an air intake formed on the front of the bike in the form of an air scoop (with a particulate filter), the exit holes could be on the motor plates near the windings (so the air passes over the windings to get out, with mesh screens over the holes), this would enable proper air cooling, and at the same time remove the possibility of dust getting in. Also an inline fan (many high output RC ducted fan kits would be ideal for extreme CFM!) coupled to a thermostat on the motor could be used to assist the ram air effect from the forward motion of the bike during times of extreme ebiking :lol: . So this system could be set up so it is totally automated, and would be great for extreme high power setups 8)

 

[solarbbq2003]

damn thought it might work, oh well back to the drawing board

 

[potatonet]

am I going to have to draw my system for people to understand it?

 

[The Stig]

The oil cooling could work, but! you have to take into consideration the effect of the viscosity of the oil/coolant acting between the stator and the magnets as it is a tight gap, so it will act like a torque converter, like which joins your auto transmission to the engine of your car, which may reduce your efficiency, the faster you go, the more friction would be generated.

Also, Air, when it is enclosed acts as an excellent insulator, thats the reason why double glazing is so effective, and other insulations act to trap air in order to retain heat. So any form of cooling fins to act on a sealed air cavity will probably have little effect. The most effective way would be to remove the hot air from inside the casing. If the shaft was bored and joined with flexible tubing to an air intake formed on the front of the bike in the form of an air scoop (with a particulate filter), the exit holes could be on the motor plates near the windings (so the air passes over the windings to get out, with mesh screens over the holes), this would enable proper air cooling, and at the same time remove the possibility of dust getting in. Also an inline fan (many high output RC ducted fan kits would be ideal for extreme CFM!) coupled to a thermostat on the motor could be used to assist the ram air effect from the forward motion of the bike during times of extreme ebiking :lol: . So this system could be set up so it is totally automated, and would be great for extreme high power setups 8)

Thats not quite how Torque converters work... They dont really use friction as the driving force, they use the momentum of the fluid pushing against fins. (From what I gather watching this vid http://www.youtube.com/watch?v=MvLoX0z9qoY)


Come on people don't give the oil cooling idea the back seat!


I know the thread is about air cooling but this could be a lot easier and more effective! I think it has potential to provide excellent heat transfer from the stator to the outside of the casing, rather than the insulation that the air provides. The only problem it might cause is if it degrades the adhesives in the motor which seems highly unlikely, Reid Welch has flooded his Ezee hub with oil and kept it partially filled for a couple months and has had no problems yet. He has also observed no loss in efficiency while running the motor with little oil in it. http://endless-sphere.com/forums/viewtopic.php?f=6&t=7454&hilit=ping+battery&start=255#p148040


I think its worth considering that the oil might not add much friction to the system because any friction would occur between the flat, continuous surface of the magnets and the surface of the stator. You would only add enough oil to just touch those two surfaces when the motor is spinning fast. From the crystalyte website I see that the "available" rotors on the LEFT have nice flat surfaces. I suspect the ones on the right are very rare.

The other surface the oil would touching at high speed is this the stator. It seems to have a nice flat surface too. Not sure if the slots in the stator would cause much friction but if they do they could be filled with something so the surface is completely flat.

All I'm saying is it seems like having oil in there would be nice and frictionless. I know some chemical engineers and I can ask them if they think oil could degrade any type of adhesive, which is pretty unlikely because that would be a quite a design flaw for an adhesive.

 

[stew007]

yep, your right enough so it seems like this will be good idea, so lets hope for some good results the thinner the liquid the less friction. A non conductive liquid, with corrosion inhibitors http://www.acousticpc.com/feser_one_uv_blue_f1_non_conductive_coolant.html

 

[The Stig]

yep, your right enough so it seems like this will be good idea, so lets hope for some good results the thinner the liquid the less friction. A non conductive liquid, with corrosion inhibitors http://www.acousticpc.com/feser_one_uv_ ... olant.html

That may work even better, using some really low viscosity liquid like coolant

That particular one has corrosion protection for "COPPER, ALUMINIUM, BRASS and NICKEL." I think there are other metals in the motor's magnets.

 

[TylerDurden]

You would only add enough oil to just touch those two surfaces when the motor is spinning fast.

If that's were case, how much heat conduction could you expect: stator->oil->case... and how much surface area would the oil cover in areas that can expell heat (side covers)?

Also, How would you determine that amount?

That may work even better, using some really low viscosity liquid like coolant

Electrically non-conductive, of course...

 

[The Stig]

You would only add enough oil to just touch those two surfaces when the motor is spinning fast.

If that's were case, how much heat conduction could you expect: stator->oil->case... and how much surface area would the oil cover in areas that can expell heat (side covers)?

Also, How would you determine that amount?

A hell of a lot more than air! The stator is the part that heats up and there is a nice big surface area around that stator. The oil would move that heat to the casing. Casing, side covers... it's all one piece. It gets a very big surface area and gets lot of wind so it will dissipate that heat. You could even put some heat sink compound were the spokes attach to the hub so the spokes act as fins.

That may work even better, using some really low viscosity liquid like coolant

Electrically non-conductive, of course...

Yup, just like oil, a very non-conductive substance.

 

[TylerDurden]

The stator is the part that heats up and there is a nice big surface area around that stator. The oil would move that heat to the casing. Casing, side covers... it's all one piece.

I'm skeptical.
Based on the above illustration, the oil would be mainly between the laminations and the magnets; barely touching the sidecovers, which have the most surface-area/mass . The sidecovers only contact the case on the flange... a few square inches at best.

By contrast, airflow in the motor is turbulent, not pinned to the perimeter by centrifugal action like the oil is. Simple open ventilation may cool much better than oil, unless the oil is circulated through some sort of heat-exchanger.

 

[potatonet]

and what did I say?

-.-

 

[Ben]

I like potatonet's idea.

Link was thinking about doing something quite similar a while ago:

http://www.endless-sphere.com/forums/viewtopic.php?f=3&t=7296

 

[steveo]

Hey Everyone,

I can not believe the amount of replies I have gotten on this subject .. !! .. There have been many great suggestions made on how to cool this hub motor .. some very intersting ones as well ..

Personally I still think air cooling is the best & EASIEST way to cool your own x-lite motor ..

may not be the best for motor life .. however .. some precautions could be meet to do you best to ensure long engine life!

There have been a few suggestions .. but not many on if we where to drill out the side covers.. what is the best way to have air forced in to cool the windings most effectively?

-steveo

 

[Zoot Katz]

. . .
There have been a few suggestions .. but not many on if we where to drill out the side covers.. what is the best way to have air forced in to cool the windings most effectively?

The general rule of thumb for drillium is to keep drilling until the part fails, then eliminate the last set of holes on the next one.

 

[curious]

Technically ugly but you can get coolant in/out the hub in a closed system (potatonet idea) without custom axle by:
- replacing two phase wires with short pieces of small diameter copper tube covered with heat shrink isolation;
- running these pipes where wires currently are;
- attaching inner and outer exchangers to these two pipes with non-conductive couplers;
- soldering the replaced phase wires to the corresponding tube inside/outside before couplers.

 

[curious]

But I am still kind of like the helium fill idea. I wonder if one properly seals the sideplates and wire path (also good for waterproofing) how fast helium will diffuse from the hub without excess pressure ? OK helium is leaky but it has to be replaced with air, otherwise there will be negative pressure in the hub.

If suitable helium concentration can remain there for a week or so what is the big deal keeping a helium tank in the garage ? Will keep kids happy. And one could be proud of using true nuclear reactor technology in their hub