Cooling fans inside Hub motors

[Cowardlyduck]

Keeping all the holes toward the outer diameter will help. The stress around the axle is much higher.

Correct, and you would think that if I would see a failure, it would have been on one of my other hubs with the holes near the axle.

If I followed Kiriakos advice my hub would be white, sealed, and probably overheat.

Cheers

 

[John Bozi]

Must agree that it looks like too much has been removed.

I was worried about mine but made sure I didn't go past 50% of the area. ie 25mm hole with 25mm left before the next 25mm hole. Yours look over that.

Having said that if you ride mostly slow and the wheel fails I wouldn't be as worried if you were planning to go 60+ kmh....

I look forward to the results of this bike...

 

[ebikedelight]

I would imagine there has to be a better way to allow airflow thru these hub motors . Cutting large holes in areas that are prone to get wet and allow water/ moisture , inside the hub itself, does not seem like a solid alternative.


Im wondering if some type of airflow couuld be achieved thru the axle itself. One side of the axle is already hollowed out to allow phase/ sensor wires to exit . Im wondering if the whole axle could be drilled out/ hollowed out enough to allow airflow to enter the inside of the hub. A flexible plastic tube could then be inserted inside the hollow axle and the top of the tube ran up under the seat facing forward, which would allow forced air to enter the tube , into the hub , while still keeping the hub relatively water proof.

 

[madin88]

Im wondering if the whole axle could be drilled out/ hollowed out enough to allow airflow to enter the inside of the hub. A flexible plastic tube could then be inserted inside the hollow axle and the top of the tube ran up under the seat facing forward, which would allow forced air to enter the tube , into the hub , while still keeping the hub relatively water proof.

you need a compressor to push enough air through a small hole in the axle. IMO no good solution. A watercooling system is what you want then, or something similar like i did: http://endless-sphere.com/forums/viewtopic.php?f=2&t=66625#p1010404

 

[Cowardlyduck]

Well my attempt is about simplicity and effectiveness. So far with all my previous attempts (with more and larger holes) I have yet to experience any structural failure, or any stones/sticks/mud/water etc entering the hub.
Read the rest of this thread for proof.

The only issue was a build up of dirt/dust over time which I unintentionally made worse using WD40 on the windings.
This time around I will use some more filtering, and have painted the windings, so any dust/dirt build up should be able to be blasted using compressed air periodically without any drawbacks.

Unless you show me an example of how this method of cooling has actually failed in the past I will forge on ahead to (hopefully) proving it's success story.

Cheers

 

[Offroader]

I would imagine there has to be a better way to allow airflow thru these hub motors . Cutting large holes in areas that are prone to get wet and allow water/ moisture , inside the hub itself, does not seem like a solid alternative.


Im wondering if some type of airflow couuld be achieved thru the axle itself. One side of the axle is already hollowed out to allow phase/ sensor wires to exit . Im wondering if the whole axle could be drilled out/ hollowed out enough to allow airflow to enter the inside of the hub. A flexible plastic tube could then be inserted inside the hollow axle and the top of the tube ran up under the seat facing forward, which would allow forced air to enter the tube , into the hub , while still keeping the hub relatively water proof.

This would help but I think the problem is you can't get that much air through a small tube. Anything is better than the way the motor is all sealed up and the windings sitting in 100c heat.

I guess you could hollow out the other axle. But if you were going to do that then just put water cooling through the hose, as this has been done already.

 

[pendragon8000]

I'm not dead... after drilling the shit out of my hubs. woo!

haha. At first I was hesitant to drill allot. but think about what breaks and where power goes.. the rims and spokes will break first. and no motor power is transmitted through the side plates, only pedal and braking power. even around the axle I have drilled 6 x 19mm holes and run 6kw doing big jumps.

also consider the power running through 36 x SS spokes 3mm wide vs no power on the side plates about twice as much material at the lowest cross sectional area, if drilled like CD has. I cant think of any side plates actually breaking TBH. Ive seen spoke flanges break but thats between the magnets and gound, ie under load from the motor.

How long till some new results CD?

Edit:
Also what cfm value are those fans ? I was just looking on digi key and refined search to 40mm fan 15mm thick
http://www.digikey.com/product-detail/en/AFB0412SHB/603-1006-ND/1014337
14.8cfm 3watt

 

[Cowardlyduck]

Thanks for the support pendragon. As you pointed out, side cover holes haven't caused very many failures, and in my case, this last job has the least amount of metal removed of any of mine yet, so highly unlikely to fail.

I'm still working on the motor mods, but progress has been slowed recently due to my soldering iron dying on me. I've been putting up with a crappy 50/100w Bunnings soldering iron for so long now, so it was a welcome opportunity to buy something decent. I'm yet to try it, but a new Hakko FX-888D just arrived on Friday, so as soon as I get some time I'll solder up my phase leads (again). I decided to ditch the original plan which was to use the original phase wires till just outside the axle, then mate them to 8awg silicone wire, and am now going to run 12awg silicone for the entire phase wire run. To achieve this I've copied Allex idea of removing the silicone insulation for the section through the axle and replaced it with heat shrink wrap.
http://endless-sphere.com/forums/viewtopic.php?f=6&t=62650

This worked well for Allex and allowed him to run 11KW through his 10Awg wires. I'll be happy if I can manage over 7KW, so 12awg should be fine for me.

As for the fans, these are the one's I used:
http://www.rcmart.com/rc-yeah-racing-ya0201-tornado-high-speed-25x25mm-p-29521.html

They claim 5.13CFM, which is more than double my previous attempt and for 25mm fans is pretty impressive. They do make a lot of noise however, so a switch to turn them on/off will be a must.

Cheers

 

[pendragon8000]

I've been putting up with a crappy 50/100w Bunnings soldering iron for so long now, so it was a welcome opportunity to buy something decent. I'm yet to try it, but a new Hakko FX-888D just arrived

I had a bunnings soldering iron die on me to, but i was using it as a home brew beer heater :/ . but those Hakko's have had good reviews. nice one. looks like you have things on track to a great mod. have you considered a thermostat or speed controller? manual on -off-auto switch might be nice, but require an extra wire through the axle.

 

[Cowardlyduck]

I had a bunnings soldering iron die on me to, but i was using it as a home brew beer heater :/ . but those Hakko's have had good reviews. nice one. looks like you have things on track to a great mod. have you considered a thermostat or speed controller? manual on -off-auto switch might be nice, but require an extra wire through the axle.

Yeah - bought the Hakko based on the good reviews and cheaper price compared to other stations.
I'll be running a temp display, as I did with this mod previously, up in the frame where my CA used to sit, so the 'thermostat' will be me essentially.
On top of that, I will be running the Adaptto temp probe which will automatically reduce power should things get too hot anyway, but that's unlikely.

As for the separate wires, I already have them. I'm running the fans off the battery directly wired in series. So I have already run some new 24awg silicone wires for that. My axle is going to be tight...in all I will have:
3x 12awg silicone - Phase wires (reduced with heat-shrink)
2x 22awg silicone - Fan wires
2x 22awg stranded (original) - Hall sensor power wires
3x 30awg Teflon - Hall sensor (sensor) wires
2x 30awg Teflon - Temp probe wires
1x 30awg Teflon - Adaptto temp probe wire (grounded through halls)

If I can't fit all of the above, I might swap the 2x 22awg stranded hall power wires for some of the 30awg Teflon wire as I think it would be able to carry the low power levels fine. If I still don't have enough room after that I can remove the silicone insulation from the 22awg silicone fan wires and replace with heat-shrink like I did for the phase wires to give a small amount of room back.
On top of all that, I did already grind out 1-2mm of extra metal from the axle slot to accommodate the extra wires, so it should work out.

Fingers crossed it all fits!

Cheers

 

[pendragon8000]

Yeah a dremel will take out a bit of the axle easy and I was surprised how much easyer it is to get wires in with only shaving a little off.

 

[John Bozi]

What do you guys know of or think of heat spikes?

For me vented motor and even letting the motor cool right down 60 degrees and then thumping 5kw up seriously steep stuff, I am pretty sure is what destroyed my last halls and my finishing temperature was below 70 degrees.

I have no idea how forced air with fans would come into the equation too as the air maybe cool everywhere or might be just one spot not getting the same cooling?

How water proof did you say those fans are? My mate rode his vented hub straight through water filling up the hub and rode off with no problems....

 

[Cowardlyduck]

What do you guys know of or think of heat spikes?
For me vented motor and even letting the motor cool right down 60 degrees and then thumping 5kw up seriously steep stuff, I am pretty sure is what destroyed my last halls and my finishing temperature was below 70 degrees.
I have no idea how forced air with fans would come into the equation too as the air maybe cool everywhere or might be just one spot not getting the same cooling?

John, I suggest re-reading page 2 of this thread as all the answers your looking for are there, but to make it easy for you, and others to see the info:
http://endless-sphere.com/forums/viewtopic.php?f=30&t=56965&start=25#p946731

As you can see, the fans barely make a difference to the heat spike...they just help cool it off faster/sooner after the fact which in turn allows for another heat spike to be more easily absorbed. It's all about the minimisation of the cumulative effect of heating from spikes over time. If you ride up 4-5 steep peaks in rapid succession without active cooling, you can expect to be at some very high temps. Do the same with active cooling and the moments between spikes will cool back down enough to make the end temp substantially lower.

How water proof did you say those fans are? My mate rode his vented hub straight through water filling up the hub and rode off with no problems....

Also from page 2 of this thread:
[youtube]iMIEGfayg30[/youtube]

I did this with my previous fan cooling setup ACTIVELY RUNNING at 15V. The water level easily reached the lower holes of the hub and there were no issues at all afterwards!
If that's not a testament to this method coping with water (and mud, and dust, etc) then I don't know what is.
With my latest mod I've even gone a step further with the painted stator, and I will also be using filtering mesh over the inlets as well, so I do not expect any issues at all. I think it will still be wise to periodically open up the motor to inspect how it's going also, but maybe once every 12 months or so will be sufficient.

Cheers

 

[Offroader]

I'm just starting to work on the air duct edf fan cooling that I think should be as good or maybe better than water cooling.

I'm building the wheel right now for my 2nd cromotor that I will be air cooling. I needed to reglue the magnets in the motor. I will then have to figure out how to make the air duct, but it shouldn't be too hard.

I can tell already with the weather warming, but not yet that hot, that I have to sometimes take breaks to let the motor cool off, I don't want to deal with this during the summer as once the motor gets fully saturated with heat, even if you let it sit and cool for 10-20 minutes, it will heat right back up again in just minutes.

I have to finish building and truing the wheel.
Then I want to test ride the repaired motor for a few days.
After the motor seems to work fine, I will then open it up install a 30mm EDF fan, install the air duct, drill a few holes for the intake and exhaust. Then I'll put it to the test to see just how well this will work.

 

[Cowardlyduck]

Then I'll put it to the test to see just how well this will work.

Great stuff Offroader. Can't wait to see your results with some EDFs. They should prove extremely effective IMO. The only catch will be the epic noise...but who cares about that!

Cheers

 

[John Bozi]

thanks for the refresher,

couldn't see what the cool down period was... stop the bike? My new found and tested moto is keep it going before it needs to stop.

I love my hub as my main ride and have trialed mid drives only and find the gear changing is ok for pussyfooting around simple terrain but not complex stuff. I don't sit well with the mid drive clan either as they just don't understand what I say about how you just can't change gears with huge amounts of power without first pedal powering to check first. It only takes a few poor shifts before you blow the chain.

All I can say is without hopefully sounding like I am hijacking your thread, try adding 5kgs of a small mid drive motor with a dedicated gear to handle the steep and or slow stuff, with the hub still the main ride.

Instead of having to stop to cool, you can choose when to crawl before you run.

The question would be whose method would see the ability of using the hub at its peak performance more during a set length ride, or reach the final destination quicker even..

 

[madin88]

looking forward for your testings offroader. i very like that you use an airduct and and EDF please post pics.
good success^^

 

[Cowardlyduck]

thanks for the refresher,

couldn't see what the cool down period was... stop the bike? My new found and tested moto is keep it going before it needs to stop.

I love my hub as my main ride and have trialed mid drives only and find the gear changing is ok for pussyfooting around simple terrain but not complex stuff. I don't sit well with the mid drive clan either as they just don't understand what I say about how you just can't change gears with huge amounts of power without first pedal powering to check first. It only takes a few poor shifts before you blow the chain.

All I can say is without hopefully sounding like I am hijacking your thread, try adding 5kgs of a small mid drive motor with a dedicated gear to handle the steep and or slow stuff, with the hub still the main ride.

Instead of having to stop to cool, you can choose when to crawl before you run.

The question would be whose method would see the ability of using the hub at its peak performance more during a set length ride, or reach the final destination quicker even..

The cool down period was stopping at the top. Video here if you feel like boring test results.
[youtube]P-VXS-aZZkU[/youtube]

A mid drive is off the cards for me for various reasons, but mainly due to the added complexity.

The thing I don't get is why active cooling isn't more sought after for super high performance.
I don't remember where exactly, but LFP stated it nicely when he said something along the lines of; an electric motor's power is only limited by the rate at which heat can be removed from it.

It makes me wonder why people don't get a small, light weight electric motor in a drag car/bike, then dump a bunch of liquid nitrogen through it as they smash 1000's of amps through it to blitz all the drag records...maybe it's not that simple, but I can't see why it wouldn't work.

Cheers

 

[Offroader]

looking forward for your testings offroader. i very like that you use an airduct and and EDF please post pics.
good success^^

Hi madin88, I'm trying to figure out for the air duct cooling how best to drill the side cover. Maybe you could offer your thoughts.

I want as little holes as possible in the side cover, only to efficiently allow a single 27mm EDF fan to have enough holes for intake and exhaust.
I don't want additional holes in the motor for air cooling when the fan is off, This will just add to dirt getting inside the motor.

Am I better off drilling a lot of smaller holes or a few larger holes? I figure drilling more smaller holes will act better as a screen to keep larger particles getting inside the motor. Will I need more smaller holes in surface area compared to if I drill larger holes? What I don't know is the physics of air flow, does the air going through smaller holes slow the air flow down compared to having a single large hole of the same area of all the smaller holes?

That being all said, how much area of holes do I need for a 27mm edf fan? Should it equal 27mm in area as that is the size of the fan opening area, or does it have to be more, also taking into account if I decide to drill more smaller holes or fewer larger holes?

Should I spray anything on my windings or stator to protect the motor? I know this will lower the cooling ability, but do you think it is necessary?

Hopefully you can put some thought into these issues and let me know what you can come up with. If anyone else has any thoughts on the matter I will gladly like to hear them also.

 

[Cowardlyduck]

Hey Offroader, you've somewhat hit the nail on the head with your dilemma there.
For good air flow you do need larger holes, but for good dirt/dust filtering, smaller holes is best.
With your EDF's however, I doubt you really need to have large holes for air flow since the EDFs will generate a lot of suction/pressure to overcome a lot of restriction.
In your case I would recommend going with smaller holes or filters over larger holes if that's the only choice.

My plan is to use those plastic bungs I bought previously with some shade-cloth acting as an intake filter stretched over a hole drilled in the middle of them.

Through some very rudimentary testing (basically by feel) I think the shade cloth blocks about half the air flow. I don't mind this so much since these fans have over twice the CFM of the ones I used previously. Should it end up being too restrictive, I can easily remove the screen, or bungs to make a different pattern or try a different type of filter, etc.

If your worried about what might work, try doing as I have, and drilling holes you can put something into like a bung or drain filter, etc. Then if you don't like how it's working, just change out the bung, or filter.

Cheers

 

[Routybouty]

Any updates with EDFs? I was excited to see those in action!

 

[Cowardlyduck]

Likewise, I wouldn't mind hearing about the EDFs performance, but if Offroader's half as busy as me atm, I wouldn't expect anything anytime soon.

I'm still progressing on my mod, but it's being held up by my other mods to my new controller as well...doing all the little things now which take waaaay too much time. Just finished soldering up my throttle and regen harness for my Adaptto last night.
I don't think I posted this hear yet, but my Adaptto is keeping in-line with the motor mods.

I've decided not to bother with the plastic bungs or any kind of filter on the motor side covers for now. It's just too much hassle for not much reward and an unknown hit on air flow performance.
I will just have to periodically open up the motor to clean it out and possibly replace bearings. I don't mind doing this if it means I never need to worry about overheating

Cheers

 

[Offroader]

I've had a bit of a set back with the edf. I laced my older 2nd cromotor, the motor I was going to use for the project into a new rim, I then had the wire cut near the axle on my 2nd ride with the motor from a zip tie which was my fault really, and I was even thinking if that could happen before it happened.

This shorted my controller so I had to replace the smallest resistor to fix it.

The other issue that kind of made me lose a bit of interest is I could swear my 2nd cromotor doesn't have the same torque as my newer cromotor. Which could make sense because I melted the glue on the magnets and heated it up over 150c. But I shouldn't let this kill the project as I can easily swap everything over to my newer cromotor if it works out.

I plan on working on this project full time now as temps are starting to become a problem with the summer approaching. Once the motor hits about 100C and gets fully saturated with heat, it just takes hours for it to cool down. If I let it cool down for 20-30 minutes it will cool say from 100c to 65c, but it will only take about 5 minutes for it to be hitting 100c+ again. The motor just can't shed the heat fast enough.

 

[burningwings]

Since the motor is moving why not bore holes and put fan blades on the rotor as John did ? Most electric motors have built in fan blades way more simple solution.

 

[Offroader]

I have to mount the air duct and cover the large holes with plastic. Is epoxy the best way to do this?

The only other alternative I can think is to tap small holes and use tiny screws to hold everything together.