It's all achievable. ICE cam and crank seals that I've seen use a spring-energised rubber lip seal. An O-ring might work instead for the relatively low speed/mileage a hubmotor does compared to an ICE. I believe in both cases it's important that some oil continually reach the seal in order to lubricate it. The surface finish on the motor shaft would probably have be improved in order not to destroy the seal. Hardness of typical hubmotor shafts is lacking, but wear of the shaft under the seal may not be an issue.
Definitive Tests on the Heating and Cooling of Hub Motors
- Thread starter justin_le
- Start date
spinningmagnets
100 TW
That Inpro seal link (two posts above this) is pretty sweet, but...I doubt they have an "off the shelf" solution for hubmotor shafts (geared hubmotors, since that's the "go to" method for that style). I suspect there might be more luck looking at ICE motor crankshaft seals, maybe pitbikes? They are a well-understood design, and leak maybe a spoonful of lube-oil per year, with the 3000-RPM small engines having an output shaft with a diameter near the size we are looking at (chainsaws, etc?)
robbie
1 W
- Joined
- Sep 28, 2012
- Messages
- 50
I would also consider looking into sealing design on dirtbike/motorcycle output gear shaft seals.
Dirtbikes especially see a lot of debris/water and are typically oil filled on the other side of the transmission case.
Car ICE crankshafts are comparatively tame in terms of contamination when say compared to wheel axle bearings or drive shaft seals, not to mention the machining tolerance on hub motor axles may not be up to sealing spec (they may need to be ground for a good seal).
Just my two cents.
-Robbie
Dirtbikes especially see a lot of debris/water and are typically oil filled on the other side of the transmission case.
Car ICE crankshafts are comparatively tame in terms of contamination when say compared to wheel axle bearings or drive shaft seals, not to mention the machining tolerance on hub motor axles may not be up to sealing spec (they may need to be ground for a good seal).
Just my two cents.
-Robbie
I'd think the axle seals found on motorcycle wheels would be up to the task of sealing in the oil. They're similar size, turn in the same RPM range, and can see similar temperatures.
For something a bit more robust, the crankshaft seals found in 2-stroke engines should work, too. The Yamaha RD350-400's had teflon crank seals.
For something a bit more robust, the crankshaft seals found in 2-stroke engines should work, too. The Yamaha RD350-400's had teflon crank seals.
I also think oil cooling could be done, but we should not forget that the axle has a hole for the wire.
moreover the single wires itself work a bit like a tube because of capillary action and pressure difference between inside and outside will push oil out.
moreover the single wires itself work a bit like a tube because of capillary action and pressure difference between inside and outside will push oil out.
litespeed
100 kW
I used some small ignition wrenches. I put my whole hub sink together with the bolts loose a couple mm and left one bolt off. Put the artic paste on and carefully pulled each section through the spokes, train style. Then added the last bolt and tightened the rest up. Took about 10 mins max.
Tom
Tom
mrbill
10 kW
Jestronix said:
I found that only 8mm open-ended wrenches on bolt and nut would fit. I would like to have been able to fit a ratcheting wrench, but even a miniature non-ratcheting box wrench ran afoul of the heat sink stub fin adjacent to the mounting tab.
In a nutshell, they work well. My initial review of hubsinks is that they are worth it. The temps still get up there but takes longer to get there and it cools down really quickly. I mean after riding SingleTrack (most flat but horse trails) for 30 min, it went to 84c. When I went to stop to check the motor, it went to 32 in a minute which is lowest adappto shows. Towards ends of ride I got up to 134c with ovs 7. I stopped for 5 min and was down to 107c. I will do some more testing. Anyone else get similar? I look forward to seeing Justin's results.
John Bozi
100 kW
drew12345 said:
Hey Drew thanks for sharing your data.
84 to 32c in a minute = almost 1 degrees per second. That sounds impossible or at least a positive incredible. What was your ambient temperature? Maybe the motor wasn't heat soaked so....mmm
Sorry what is ovs 7.? 134 to 107c in 5 mins is where I would have though a much quicker drop being further from ambient. But again heat soak by this time and it sounds right. But 10 times longer to cool is odd.
What is your motor and FF condition? Is it vented too? how much FF did you use and is it in there still? (might be my eyes but it looked vented in the pic above.)
cheers
litespeed
100 kW
I finally got to put a good hard but short run on my Hubsinks now that I have ferrofluid and boy what a change it made. Spots were I would peak at 175 degrees stayed in the 150's. As previously mentioned I still get peaks but the temps drop quickly. I was peaking at 150 to 180 amps till my battery was hitting low volt and the temps were infact lower than ever before.
I'm going to go hit the trails hard here in just a bit and see what that does. Still haven't got a card reader for my iPad so no GoPro, iPhone stills will have to do.
Tom
I'm going to go hit the trails hard here in just a bit and see what that does. Still haven't got a card reader for my iPad so no GoPro, iPhone stills will have to do.
Tom
litespeed
100 kW
Well I finally got a chance to put a good hard ride on the Hubsinks/ferrofluid combo and the verdict is in.
My rides have now gotten shorter!!! I can run harder longer and it sucks the power right out of my battery. I used to have to take it easy for awhile to cool the motor down....not any longer. Thought I'd be stopping to take pictures once I heated things up but that didn't happen. Now granted I wasn't doing any hill climbing as most of this was pretty flat like a motor cross track but I ran the trails 20 to 30 mph average. I just couldn't cook the motor. I was really on the throttle hard, not flowing. Coming out of hair pin corners full throttle and the 205 still kept its cool.
I need to go to a 20s13 to 15p VTC5 pack which I plan to do this winter. Maybe with a 39 amp pack capable of 200 amps continuos I can heat the motor up better.
Thanks a lot Sketch, I really appreciate you contribution to the community and to my enjoyment.
Tom
My rides have now gotten shorter!!! I can run harder longer and it sucks the power right out of my battery. I used to have to take it easy for awhile to cool the motor down....not any longer. Thought I'd be stopping to take pictures once I heated things up but that didn't happen. Now granted I wasn't doing any hill climbing as most of this was pretty flat like a motor cross track but I ran the trails 20 to 30 mph average. I just couldn't cook the motor. I was really on the throttle hard, not flowing. Coming out of hair pin corners full throttle and the 205 still kept its cool.
I need to go to a 20s13 to 15p VTC5 pack which I plan to do this winter. Maybe with a 39 amp pack capable of 200 amps continuos I can heat the motor up better.
Thanks a lot Sketch, I really appreciate you contribution to the community and to my enjoyment.
Tom
spinningmagnets
100 TW
The hotter the side-plates and fins are, the faster the heat sheds to the surrounding air. I know that it seemed to me earlier that the heat of the stator could radiate to the aluminum side-plates fairly easy, because the air-gap on the sides of the coils is thin. However, I cannot argue with the results. Even though the central rim is steel (as a backing for the Neo magnets), it has a physical connection to the aluminum sideplates, instead of an air-gap.
As far as I know, there may even be a thin ring of the Ferro Fluid that is touching a portion of the aluminum side-plates. Any heat that is shed by the aluminum fins touching the steel central rim can only be good, and apparently...it is a major help, rather than the small assist that I originally thought it would be.
I need to buy a pistol thermometer...
As far as I know, there may even be a thin ring of the Ferro Fluid that is touching a portion of the aluminum side-plates. Any heat that is shed by the aluminum fins touching the steel central rim can only be good, and apparently...it is a major help, rather than the small assist that I originally thought it would be.
I need to buy a pistol thermometer...
macribs
10 MW
- Joined
- Jul 22, 2014
- Messages
- 3,702
I just came across the Zev electric (maxi) scooters. Those uses oil filled hubs it seems. Has anyone had the chance to take a peak at those maxi scooters?
If Zev is offering oil cooled hub motors to paying customers surely Zev must have came up with a solution to prevent oil from leaking and making a mess in customers garage or on their rare stone covered drive way. Both side covers and axle must be sealed tight. Anyone live close by that have been in their store to look at those BEV maxi scooters? World fastest electric scooter according to their website.
They even have a new leaning trike and a new motorcycle, click to see. Didn't wanna litter too much with OT pics.
If Zev is offering oil cooled hub motors to paying customers surely Zev must have came up with a solution to prevent oil from leaking and making a mess in customers garage or on their rare stone covered drive way. Both side covers and axle must be sealed tight. Anyone live close by that have been in their store to look at those BEV maxi scooters? World fastest electric scooter according to their website.
They even have a new leaning trike and a new motorcycle, click to see. Didn't wanna litter too much with OT pics.
mrbill
10 kW
Folks:
I recently completed some controlled tests on a course with a significant hill climb, using an Edge 1500 DD hub motor as a platform and wrote up report in my blog.
https://mrbill.homeip.net/hybridBike.php#edge1500Testing
Summary:
Using Statorade my hill climb went from 8 cooling stops to 3. Adding Hubsinks my climb went from 3 cooling stops to 0 cooling stops.
Both of these concepts work, but the Hubsinks work best on motors that use Statorade. I did not test the motor with Hubsinks and no Statorade.
I recently completed some controlled tests on a course with a significant hill climb, using an Edge 1500 DD hub motor as a platform and wrote up report in my blog.
https://mrbill.homeip.net/hybridBike.php#edge1500Testing
Summary:
Using Statorade my hill climb went from 8 cooling stops to 3. Adding Hubsinks my climb went from 3 cooling stops to 0 cooling stops.
Both of these concepts work, but the Hubsinks work best on motors that use Statorade. I did not test the motor with Hubsinks and no Statorade.
litespeed
100 kW
Nice write up!
Tom
Tom
John Bozi
100 kW
Offroader said:
Would be great if it were possible to have transparent side cover, or much easier someone with a brand new hub and a large vent hole looking straight at the gap in super slow motion with FF inside. To see if the ff does spray out of where we want it and what rpm.
When I went over to Sketches he showed me a motor that had been pulled apart and the FF was just sitting on the magnets in the open air who knows how long while waiting to be put back together again. It wasn't going anywhere, not evaporating...
Emmett
10 kW
I've been using oil cooling in a three hubs for 23 months. Riding rough off-road at speeds of 5 to 55km/h and it works great. A hubsink (on order) will I hope take it to the next level and I'm looking forward to that.
I'm intrigued by some posts here about sealing hubs being impossible. I think it pretty easy, and when a small amount of oil does get out, it's doesn't matter if you use odourless castor oil.
With 90 to 100ml of oil in a H40 or TC30 motor, I think that the drag is about 30W at around 50km/h. The exact amount is irrelevant to me, since I ride for fun and going a few km extra distance has much more to do with my usage patterns than oil drag. Besides, the cooler stator will be more efficient anyway.
To seal a hub, this is my usual procedure:
1. Use an oil resistant sealant. I use a RTV silicone intended for engine work. The so called "liquid gasket" sealant products.
2. Thoroughly clean the surfaces between the side plates and hub ring. To bare metal every time. If necessary use a spinning wire brush and brake cleaner with compressed air blower. Use a thin layer of sealant on both surfaces. Never get any sealant in the threads or bolt holes. Easy being careful. Use blue loctite on all bolt threads so the side plates never comes loose. This means your sealant it sheer loaded only and stays bonded. Let your bolts take the tension.
3. Use sealed bearings and keep your outer axle seals in reasonable condition. Since they help.
4. Drill a 1.0mm breather hole near the freewheel sprocket, for pressure equalisation. A tiny leak here is no issue.
5. Seal around the wires in the axle slot. For the phase wires I like to use the fattest silicone wire I can fit along with the thin bundle of hall (and temp) wires. Bundle the thin wires together and put some silicone inside the heat shrink. I don't use a wrap to bundle the phase wires. Instead grind away any sharp metal in the slot and lay/pull the phase wires through with silicone all over them. Use heat shrink tape to hold wires pressed into the the slot while the silicone cures. Remove tape later and slide the plate with bearing and outer seal onto the axle. For protection, tough shrink wrap the three phase wires just after they exit the sealed slot. Final result = the wires+slot are sealed. Yes some oil can work along the copper, but it's insignificant in my experience.
Hope that helps.
Why bother with FF? The castor oil does thicken (at least at room temp) after it's been "cooked" a dozen or more times. So I replace it that often. It's super easy to drain and fill with an M5 drain plug in the chain side plate near the magnets. Cut your drain bolt to length and use a fiber or copper crush washer to seal it.
Doing this along with having a sealed rear sprocket freewheel also means the hub can be routinely washed after muddy rides.
I'm intrigued by some posts here about sealing hubs being impossible. I think it pretty easy, and when a small amount of oil does get out, it's doesn't matter if you use odourless castor oil.
With 90 to 100ml of oil in a H40 or TC30 motor, I think that the drag is about 30W at around 50km/h. The exact amount is irrelevant to me, since I ride for fun and going a few km extra distance has much more to do with my usage patterns than oil drag. Besides, the cooler stator will be more efficient anyway.
To seal a hub, this is my usual procedure:
1. Use an oil resistant sealant. I use a RTV silicone intended for engine work. The so called "liquid gasket" sealant products.
2. Thoroughly clean the surfaces between the side plates and hub ring. To bare metal every time. If necessary use a spinning wire brush and brake cleaner with compressed air blower. Use a thin layer of sealant on both surfaces. Never get any sealant in the threads or bolt holes. Easy being careful. Use blue loctite on all bolt threads so the side plates never comes loose. This means your sealant it sheer loaded only and stays bonded. Let your bolts take the tension.
3. Use sealed bearings and keep your outer axle seals in reasonable condition. Since they help.
4. Drill a 1.0mm breather hole near the freewheel sprocket, for pressure equalisation. A tiny leak here is no issue.
5. Seal around the wires in the axle slot. For the phase wires I like to use the fattest silicone wire I can fit along with the thin bundle of hall (and temp) wires. Bundle the thin wires together and put some silicone inside the heat shrink. I don't use a wrap to bundle the phase wires. Instead grind away any sharp metal in the slot and lay/pull the phase wires through with silicone all over them. Use heat shrink tape to hold wires pressed into the the slot while the silicone cures. Remove tape later and slide the plate with bearing and outer seal onto the axle. For protection, tough shrink wrap the three phase wires just after they exit the sealed slot. Final result = the wires+slot are sealed. Yes some oil can work along the copper, but it's insignificant in my experience.
Hope that helps.
Why bother with FF? The castor oil does thicken (at least at room temp) after it's been "cooked" a dozen or more times. So I replace it that often. It's super easy to drain and fill with an M5 drain plug in the chain side plate near the magnets. Cut your drain bolt to length and use a fiber or copper crush washer to seal it.
Doing this along with having a sealed rear sprocket freewheel also means the hub can be routinely washed after muddy rides.
Emmett, thanks for that great summary.
I also believe that oil leakage is mainly because of poor sealant and the lack of a breath hole.
On one of my MXUS 3k hubs with FF i have installed a Gore valve.
Do you have any experience with those, or do you know if that valve still works if the breathable membrane came in contact with oil?
I also believe that oil leakage is mainly because of poor sealant and the lack of a breath hole.
On one of my MXUS 3k hubs with FF i have installed a Gore valve.
Do you have any experience with those, or do you know if that valve still works if the breathable membrane came in contact with oil?
Emmett
10 kW
No, I have not used any valves on the breather. With a 1.0mm hole drilled in the right place the amount of weeping doesn't create an issue for me. My bike is always dirty during rides. A wipe with rag every couple of hours does the job. I can imagine my kind of usage is different to the vast majority. But I'm sure some people will create some ingenious valve solutions for breather.madin88 said:
spinningmagnets
100 TW
OK, I have the Ferro-Fluid, fins, and the fins came with a small tube to thermal paste. I'm sure the amount is adequate, and the brand is good. however, I was wondering if anyone has any ideas about the top-three thermal pastes to buy (when purchasing from North America, the paste I now have was supplied by the Australian vendor for the fins).
Since we are using a higher volume than a tiny heat-sink in a computer CPU, I would guess something that performs at about 90% of the thermal transfer as the top-of-the-line stuff would be adequate, if that also meant that it cost half as much as the best stuff.
Since we are using a higher volume than a tiny heat-sink in a computer CPU, I would guess something that performs at about 90% of the thermal transfer as the top-of-the-line stuff would be adequate, if that also meant that it cost half as much as the best stuff.
In general, any thermal paste that does not dry out or wash off should be fine.
When I used to do computer work, Arctic Silver (of whatever the latest # was at the time) was what "overclockers" typically used. I've tried bunches back then, and mostly they are all the same in actual thermal conductivity; so close as doesnt' matter--but some of them have better solvents or bases in them that don't dry out, , or that are more waterproof (for the rare situation that requires that, thermal epoxies are probably better).
For most of the stuff I've done, the plain old white titanium dioxide stuff has worked fine; I just make sure that it is ONLY used to fill the scratches and tiny gaps here and there, because any gaps big enough to require thermal paste to fill them are just gaps that block heat from passing thru anywhere near as efficiently as metal-to-metal contact.
If your heatsinks can be made to fit the curve of the hub so that there are no actual air gaps, it'll work better even wtihout any thermal paste than it would with the gaps filled with thermal paste, especially over time as environmental conditions alter the paste or remove it entirely.
I'd guess, without direct experience with the hubsinks, that because of weather and such, thermal pads would be better than paste for any gaps you can't get rid of, and then just use thermal paste for the actual in-contact surfaces to fill scratches and whatnot.
When I used to do computer work, Arctic Silver (of whatever the latest # was at the time) was what "overclockers" typically used. I've tried bunches back then, and mostly they are all the same in actual thermal conductivity; so close as doesnt' matter--but some of them have better solvents or bases in them that don't dry out, , or that are more waterproof (for the rare situation that requires that, thermal epoxies are probably better).
For most of the stuff I've done, the plain old white titanium dioxide stuff has worked fine; I just make sure that it is ONLY used to fill the scratches and tiny gaps here and there, because any gaps big enough to require thermal paste to fill them are just gaps that block heat from passing thru anywhere near as efficiently as metal-to-metal contact.
If your heatsinks can be made to fit the curve of the hub so that there are no actual air gaps, it'll work better even wtihout any thermal paste than it would with the gaps filled with thermal paste, especially over time as environmental conditions alter the paste or remove it entirely.
I'd guess, without direct experience with the hubsinks, that because of weather and such, thermal pads would be better than paste for any gaps you can't get rid of, and then just use thermal paste for the actual in-contact surfaces to fill scratches and whatnot.
Emmett
10 kW
Assuming a really accurate curvature fit of hubsink segments, does this mean a significant loss in heat conductivity will result from the the original paint on my H40 hub ring?amberwolf said:... anywhere near as efficiently as metal-to-metal contact.
Similar threads
