motomech
10 MW
I guess one can't improve on perfection.gogo said:
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Oil cooling your hub- NOT snake oil!
- Thread starter Spicerack
- Start date
GCinDC
100 MW
so if my uphill commute gets a vented 9C up to 130C regularly, would it be a good candidate for oil cooling?
i picked up some auto/marine sealant and dextron III, but am just wondering if the oil can handle that heat, or if it's better to stay vented...
keeping the motor at 80C sounds nice, but it's not gonna happen!
i'm thinking 150C is the absolute limit, for the halls, varnish etc. i have the sense that the oil will take the motor much longer to heat up, but eventually it will get hot, and probably stay hot.
i picked up some auto/marine sealant and dextron III, but am just wondering if the oil can handle that heat, or if it's better to stay vented...
keeping the motor at 80C sounds nice, but it's not gonna happen!
i'm thinking 150C is the absolute limit, for the halls, varnish etc. i have the sense that the oil will take the motor much longer to heat up, but eventually it will get hot, and probably stay hot.
andynogo, could you get it hotter than 90C, doing rigorous uphill trail stuff? how would it react? what do you consider the absolute limit?andynogo said:
wiuhh
10 mW
GCinDC said:so if my uphill commute gets a vented 9C up to 130C regularly, would it be a good candidate for oil cooling?
i picked up some auto/marine sealant and dextron III, but am just wondering if the oil can handle that heat, or if it's better to stay vented...
most car transmissions run much hotter tho they are cooled by the radiator. i doubt the temp will be a problem but if i understand what you guys are doing(new to ebike) you definateley want to vent because of tempature changes causing fluid expansion. most (all i have ever seen) transmissions/rear diferentials are all vented.
probably not relevant but you might be more worried about foaming which also shouldnt be a problem because there should be enuff anti foaming additives in any atf(eduacated assumption) for this application. as well as your not relying on the oil for lubrication so your only risk is loss of cooling. tho a long trip at high enuff rpms if theres any cake mixer scenario(for lack of a more common term) going on with any oil it can turn all your oil into useless foam. side note id also recomend you seal with rtv made to replace a transmission pan gasket(put on wet and filled with atf) you have to get from the auto manufacturer name brand silicons wont seal as well with atf. been out of the field for a lil over 10 years but dodge rtv was by far the best for atf. (no pan gasket all rtv)
ps luv this thread i hope you guys do well cuz there will probably be a bunch of us plagerizing your design so try and do a good job lives are at stake
GCinDC
100 MW
Spicerack
10 kW
Totally forgot to give you a reply yesterday but looks like you're on track. Yes, your 9C is most definitely a good candidate. Don't forget my figures are with a damaged motor- I cooked the windings so it's making alot of excess heat now. Having said that, I haven't got it above that 80-90 celcius at all but I don't have any long hills around here. I have a new set of windings now so will get onto fitting it and posting up some new results.
sn0wchyld
100 kW
auraslip said:
check the links on p4. to answer your question... no. you loose magnetisation, but gain heat tolerance before any further degradation will occur. basically you end up with a higher KV motor. You'll get less torque for a given input, and slightly lower efficiency during acceleration (and slightly lower peak efficiency too), but a higher top speed as a result.
johnrobholmes said:
from memory when I played around with a calculator on that site I linked to (on p4 I think..). temp rating actually went down with higher grade magnets. so N35's handle more heat than n40's can, Ill have to check though. this could also be why repeated overheating of magnets doesnt degrade them further (for the same max temp), as your effectively taking a n40 to a n35, or n45 to n40. In both cases your magnets are weaker, but have a higher temperature tollarance before further damage will occour.
The other major factor that affects magnets heat tollarance is their dimensions. it seems that long fat magnets like those in 80100 motors have higher temp ratings than large flat thin ones. Comparing the size of magnets on my HT with those on their site gave me a rough number of about 90-100deg before damage, though I think I'd keep it below 80 as much as possible, just to be safe.
auraslip said:
That looks like it would work (but I think you show the wheel direction backward - I get the idea). The tube might even fit inside the cover. You could use 1/4" copper tubing and a 90deg compression fitting at the end.
The open end should probably be closer to the axle than the place where it comes out so centrifugal force will help push the oil back to the motor.
cal3thousand
10 MW
fechter said:
That's how I read his drawing. The hole is closer to the center than the rest of the tube, which will allow for a centrifugal effect to keep the oil inside by flinging it away from the hole. The tube wouldn't even have to travel much, maybe 1 radian would be enough.
Great idea auraslip!
shorza
10 kW
What's the smallest diameter copper tubing? maybe 2mm?
Could this be epoxied in like the diagram above, and double as a filler hole?
Could this be epoxied in like the diagram above, and double as a filler hole?
you can purchase a couple brass fittings from the local hardware store and install them so you have a nice threaded plug that you can remove for filling the hub.
use ATF gasket sealant around both sides of the covers. I have found 100ml or so of ATF to be a good amount of fluid to use.
View attachment 2
use ATF gasket sealant around both sides of the covers. I have found 100ml or so of ATF to be a good amount of fluid to use.
View attachment 2
shorza
10 kW
Looks perfect. How did you get to first brass fitting in there? Did you thread tap the cover?
This is a clever concept to get more robust threading for a filler plug instead of the using the aluminum side cover directly. Even if the plug adapter is ground/cut thinner for clearance, the resulting threaded insert should give good service.dfar said:
(BTW - How about posting pics [in-line] instead of just as attachments? ...much easier to view...
)teklektik said:(BTW - How about posting pics [in-line] instead of just as attachments? ...much easier to view...
I was not aware I could do this, could you direct me to where I could learn to do this?
Thanks
edit (thanks for the instruction teklektik)
Sure -dfar said:
- go back to your original post with pics as attachments and click [EDIT] in the upper right corner.
- Position the cursor in the text somewhere - let's say at the end in this case.
- Go down to the bottom where your attached image files are listed and press [Place Inline] under each file.
motomech
10 MW
Why not put a couple very small vent holes inside the threaded portion of the free wheel mount and let them continually lube the DNP POSauraslip said:
This is my idea for a vent hole.
The little plastic tube fits onto a nipple. Then the tube loops around the axle so that the spinning of the axle should spin any fluid back towards the opening.
parabellum
1 MW
Why not just damage a shaft seal lip on threaded side (Little hole done with the needle) ?motomech said:
motomech
10 MW
Seriously, just drill though the seal. I used to drill them and insert a wood screw to pull them out all the time as a motorcycle tech.
Easy enough to patch or replace the seal if it doesn't work out.
Speaking of "working out', presumably, if some oil did pass from the motor into the inner mechanism of the free wheel, eventually it would escape though the gears and onto the chain. A good thing or a bad thing, depending on one's perspective. 8)
Easy enough to patch or replace the seal if it doesn't work out.
Speaking of "working out', presumably, if some oil did pass from the motor into the inner mechanism of the free wheel, eventually it would escape though the gears and onto the chain. A good thing or a bad thing, depending on one's perspective. 8)
Stone Meadow
10 W
Here's another option for venting the hub. Install on of these 'differential vents' as close to the axle as practical. That's a sintered bronze insert to permit pressure equalization, but it's essentially leak-proof.
Just four bucks from Hawaii Racing.
Just four bucks from Hawaii Racing.
shorza
10 kW
Ooh, I'm interested. Has anyone tried this yet?
Spicerack
10 kW
My concern with a sintered bronze fitting is that the oil will wick through the sintered bronze and leak more than a tube or small hole as previously described. Remember the KISS principle people 8)
Stone Meadow
10 W
Fair enough. I was only thinking that the breather plug might allow equalization without the danger of admitting water and other shyte, while not leaking any more than a plain hole.andynogo said:
hjns
100 kW
GCinDC said:
I think only adequate testing will tell. I am still struggling to find time to rewire my 9C and add the thermistor. But one of the variables to be tested under aircooled versus oilcooled condtions must be how much abuse the motor takes before going above 90oC, and how long it takes to cool down again. In other words, expose the motor to a standardized route with a known increase in altitude at a fixed current and/or fixed velocity. Once the motor is 90oC, then measure how long it takes for the motor to cool down to an arbitrary temperature (50oC ??) during a low amp high speed setting (aka WOT with the wheel in the air), after which one can safely start pushing it again.
We can all predict that the oilcooled motor will take longer to get to 90oC. However, it will be very interesting to see how fast it cools down again as compared to the aircooled motor.
GCinDC
100 MW
hole at angle:auraslip said:
This is my idea for a vent hole.
The little plastic tube fits onto a nipple. Then the tube loops around the axle so that the spinning of the axle should spin any fluid back towards the opening.
1/4" tube i think, jb welded into place inside
and outside (taped until jbweld underneath dries)
after building the (big heavy amp sucking) wheel
i tested the temps on an easily repeatable route, and will update this with data from oil filled version...
lot more detail about my ride in my thread.
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