Oil cooling your hub- NOT snake oil!

[teklektik]

I'm thinking that the tube should spiral from the side plate inlet inward toward the axle where the open vent end should be located, not outward as shown. The spinning motion of the wheel will cause oil in the tube to move outwards toward the rim so the end of the spiral tube most distant from the axle should dump into the hub.

 

[GCinDC]

we shall see!

suggestions how much oil to put in? i've got a quart...

i'd kinda like to pour it in and see it before sealing the side cover. get an idea of the volume. could be messy tho..

by injection, i'm not sure i'll ever know. and there will be counterpressure?

 

[itchynackers]

You probably won't get a good idea before sealing it up. One think I considered was to cut a slot in one of the covers, and then insert a clear window in its place, to use as a fill gauge. Even if it was a 1/8" drill hole near the perimeter covered with clear plexi, you would be able to tell how full you were just by rotating the "window" to the right position.

 

[teklektik]

Fill it like a car differential/transmission: Use the mating brass plug fill solution proposed by dfar but using your vent. Just rotate the wheel so the fill plug is at the desired depth and fill until it overflows. Use a Marinade Injector (eBay 'Marinade Injector') so the job goes quickly.

He's got some strangely encoded images that the forum won't display inline, but you can view them if you click them. Here's his first photo (re-encoded):
I might put the fill plug as far out towards the rim as possible so it can be used as a drain plug as well...

 

[grindz145]

badass!!

 

[csm]

It is good to see more people discover and document the benefit of oil cooling a hub. I predict it will become the standard in the near future.

Pioneering work was done in this area by Bowling Green State University (BGSU) Professor Anthony Polumbo in BGSU Paper "PowerDenseElectricMotor-BGSU-01566299" (0-7803-91 45-4/05/$20.00©)2005 IEEE) where they increased the power of a NEMA 215 Frame induction motor used to power a bus from approximately 10Hp to 100Hp. Not all the improvements were from oil cooling, but it sure enabled much of the increase in "Power Density."

Sadly the Electric Vehicle Institute at BGSU has been dismantled and the staff scattered... right when we on the cusp of electric propulsion. They had a great staff and great vision, just too early for stable funding...

They still seem to maintain a website. http://www.bgsu.edu/colleges/technology/EVI/

Which project was it that they used oil to cool motor?

 

[GCinDC]

 

[GCinDC]

w/o oil it took me 1 minute to get up to 70C.

w/ oil, it took 15 minutes of pulling mostly 4kw, heavy starts, stops, bad throttle.

got some weird cut outs tho. almost like hall dying, but power resumed right away. happened a bunch of times. not good.

also, i was VERY glad i removed rear caliper, as the seal on the disk side blew and a bulb of oil appeared. not sure why vent didn't work!

perhaps should have waited longer for sealant to dry. i'm used to painting caulking while wet... :?

i did some tests with round tupperware, and figured out that 1/4 full put oil at a good level:

i hated the thought of not knowing how much was in there, so decided to fill it halfway, then siphon out half of that. i ended up putting in 400 cc total, but 50cc probably leaked out axle. i made the mess so you won't have to... :wink:

and 350cc is still too much, if oil covered my vent hole, there would be too much pressure in there.

some of the work:
[youtube]XogXUBo-dtg[/youtube]

 

[hjns]

Thanks. Very good info. I do worry about the cutout. Hall issue? Does the Clyte also have a separate hall pcb?
I will cover my halls / hall pcb with silicon muck.

 

[teklektik]

... as the seal on the disk side blew and a bulb of oil appeared.

What does this mean exactly? Did the lip/retaining spring deform and actually blow out or did it just leak?

The oil seal lips are very easy to damage - normally you would never know on a hubmotor. However, if the covers have been mounted up without lubing the seal and shaft to protect the seal prior to assembly, it could have been damaged - perhaps even in a previous assembly operation. If it has no internal coil retaining spring, then it's unlikely to provide a good enough seal - replace with a standard double lipped seal of the same size.

... if oil covered my vent hole, there would be too much pressure in there.

Not really. Once vented, there should be negligible pressure differential - the vent will do its job - if it's submerged, oil will be expelled to equalize pressure.

 

[pwbset]

Hey GCinDC... thank you SO much for that "how to" video. It helps me a ton. I just got a 9C that I'm going to abuse the snot out of and this video is a great learning tool. +5 karma to you sir.

 

[GCinDC]

... as the seal on the disk side blew and a bulb of oil appeared.

What does this mean exactly? Did the lip/retaining spring deform and actually blow out or did it just leak?

The oil seal lips are very easy to damage...

sorry, that was a hasty description... i was riding along and heard an odd thump. i stopped and noticed a swell of oil on the sidecover edge, which i'd sealed w/ marine caulk - and it was the disc side, which i'd sealed the night before, so it had the night to set. but as you may have noticed, i didn't put much, and went to the outer edge of the screw holes, wanting to keep any excess away from the magnet ring... in future, i'll use more sealant.

anyway, i wiped away the oil, and saw no gap or anything. it could have been a drip build up from something else, but it wouldn't have been directly over the sidecover seal, esp if it had dripped out the axle and and down the side of the motor, which some oil had done.

what are the oil seal lips? sounds like those black rubber things that seat into the sidecover around the axle from the outside? i thought those contained the coil that everyone says cuts the wire, and i considered removing it, but i saw no evidence of the coil, and chose instead to use a wire tie to keep the wire away from that rubber.

i thought i read before that the bearing was going to have to be the barrier... now that i think about it, i should have probably caulked around the bearing. both popped off the side cover and had to be replaced. one slid halfway into place and then had to be smashed the rest of the way. probably not best practice, but i've got another hs3540 with a bearing only halfseated, or so i think, with a bowed sidecover... and i didn't want to install it that way, not with this mofo wheel.

thank you SO much for that "how to" video.

thanks. i had a heck of a red mark on my forehead from wearing the gopro (on an improvised head mount) :lol: i cut the hours and hours of searching for tools to show just the important parts, but there's a whole lot more to the job. so a much larger how to vid would have to be done, including choosing and installing your temp sensor, as well as upgrading your phase wires, which is a job unto itself on a 9C.. (which i didn't do this time, but will probably do tomorrow night, now that i'm depressed and bored that this project is over. :lol: )

Does the Clyte also have a separate hall pcb? I will cover my halls / hall pcb with silicon muck.

no separate hall pcb. mine has three (left) plus one thermistor, which i replace w/ lm35. before:

after (still wet):

i was most concerned with creating a web around the hall legs and wires, but might even suggest removing the silicon which is easy and embedding halls in jbweld.

but this is wild west territory, so good luck to you. whether it lives or dies, take lots of pics.

 

[teklektik]

what are the oil seal lips? sounds like those black rubber things that seat into the sidecover around the axle from the outside? i thought those contained the coil that everyone says cuts the wire, and i considered removing it, but i saw no evidence of the coil, and chose instead to use a wire tie to keep the wire away from that rubber.

i thought i read before that the bearing was going to have to be the barrier... now that i think about it, i should have probably caulked around the bearing.

Yep - that's probably them. I confess to never having seen an Xlyte axle, but I just checked some images and it seems it's slotted instead of bored for the wire so an oil seal on the wire side wouldn't have a complete round shaft to seal against anyway - hence the comment about using a sealed bearing and, I suppose, chalking the axle slot gap with the wires to the inner race. Looking at your images of the cover plate (other side of the motor), there is an oil seal and a shielded (unsealed) bearing (shielded = metal covers). Anyhow - here's a side view of a typical oil seal - they come in many configurations, this is the style used on both sides of BMCs:


In this illustration the bottom is the opening for the shaft and the dust lip and inner seal w/spring ride on the machined face of the shaft. As you can see in the illustration, the coil spring tensioner is inside the seal like a little necklace and holds the rubber lip pressed against the shaft.

 

[auraslip]

this thread just gets better and better

 

[dfar]

I would only use ATF gasket maker as a sealant. It has been working very well so far and was designed for ATF.
found in any local automotive section, $10 a tube. Don't be chintzy with it, make a nice fat bead, let it set for a few minutes and then tighten your hub cover down. You should push sealant out around the cover, don't wipe it off, let it all set (read the instructions for set/use). If your super picky then with a knife you can cut off the excess, personally I just leave it (the wheel spins to fast for anyone to see it anyway ). you can also put a nice dab of sealant where the wires exit the groove on the shaft. This has solved 98% of the leakage for me

As mentioned before make sure your wires are secured properly ie. tightly, but not to tightly. I had a problem with a hall output grounding due to the insulation being rubbed off from a zip-tie (not sure if the atf "pushes" the wires around more or not), now I like to put "mattress" foam around the wires just where the zip-tie will be holding them in place, no more problems since.

 

[teklektik]

 

[dfar]

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.

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.

The specs for honeywell SS41hall sensors are max 85 Celsius (however there are ones rated for 150 Celsius) therefore I don't like to run my motor over 70 Celsius (I like a bit of breathing room). this has been doable so far.

http://www.digikey.ca/product-detail/en/SS41/480-1999-ND/701354

anecdotally i wouldn't say it takes longer to heat up the motor but it does seem to stabilize at around 60celcius wherein after 60 Celsius it becomes ever harder to increase the temps and not have them drop back down. similarly it does seem to take longer for the motor to reach ambient temp after shutdown.

 

[GCinDC]

just had a romp in the woods.
[youtube]x1lO5D_1wdU[/youtube]
completely different riding. whereas it took forever to get up to 80C at street speeds, it was not hard to get to upper 90's on steep uphill sections. still much better than 144C tho...

after yesterday's run, i thought all the juice had squirted out, but some nasty jolts in on roots, etc made a nasty mess of my wheel, and the rear brakes, which i'd decided to put back into place... they're a bit more like bad mechanical brakes now...

perhaps too much oil still. i released some more, just leaning the bike over, drained easily through clear tube.

no leaks from drive side. all from disc/WIRE side. that slot is the issue. will an oil seal matter at all if there's a friggin slot underneath it? or did i read that i should load the slot up with sealant.

thanks for the ATF RTV sealant. that looks great. and i will not be chinzie with it...

how many times have you had yours open, dfar, after first oiling it?

i'll just drain as much as i can and then line the garage with newspaper...

 

[dfar]

thanks for the ATF RTV sealant. that looks great. and i will not be chinzie with it...

:lol:

how many times have you had yours open, dfar, after first oiling it?

several times (maybe 4) but it was first due to my axle breaking because of ill fitted torque arms, second due to having to change hall sensors multiple times due to the axle break and the hall sensors grounding to the axle from the insulation being rubbed off by the zip tie.

every time you take off a side cover you have to reapply the RTV sealant to ensure a good seal. Incidentally I'm on my second tube of RTV sealant :?.

I see you may ride your bike a little harder than what I do (as I only ride on the street) but I'm pulling upwards of 4500 watts from stand still and roughly 2500-3000 continuous at speeds of 60km/hr and max speed of 75km/hr or so and getting temps of around 65-70 C. also using regen for braking. I Defiantly can see the motor heating up faster at slower speeds while pulling high wattage.

I think you will find that as you ride you will see less and less fluid exiting the motor but will still have that same improved temps, in this case all you would need to do is take the motor apart and measure how much atf is left inside, the tricky part is estimating how much atf you need to "saturate" the stator. I've tried doing this but just made a mess but estimated the fluid that came out as 100ml.

By "saturate"I mean when you first put the atf in the motor, the stamped stator will "wick" up atf between the plates after some use. When the stator is "saturated" with atf fluid I find roughly 100ml of extra fluid works well to cool the motor and not have excessive atf leakage.

when I took my motor out after the axle broke, the stator, when sitting for 2-3 days, drained enough atf to soak a 1/4 thick newspaper. So the initial input of atf should be more compared to that used after the motor has become "saturated"... I think, but this is all anecdotal

 

[teklektik]

By "saturate"I mean when you first put the atf in the motor the stamped stator will "wick" up atf between the plates after some use. When the stator is "saturated" with atf fluid I find roughly 100ml of extra fluid works well to cool the motor and not have excessive atf leakage.

...So the initial input of oil should be more than after the motor has become "saturated". I think but this is all anecdotal

Anecdotal - true - but an interesting factor that has not been previously discussed. Good stuff.

 

[motomech]

Here is what I have been playing around with.


Above, use two of the disc brk. mounting bosses as the filler/check level holes



Not really planning on running great power though this mini at the moment, but this might be a way to keep the DNP freewheel internals lubed.
There is no oil seal in the motor cover plate. The idea is to remove the two bearing grease seals and let some oil pass though into the freewheel.
I am installing a bearing in the un-surported[outside]end of the DNP as Mxer did here,

http://endless-sphere.com/forums/viewtopic.php?f=2&t=36597&p=575123&hilit=freewheel+broke#p575123

Since the small diameter axle uses a spacer, the bearng is 26 X 17 X 5 mm, instead of the 26 X 15 X 5 bearing for the larger axle.
I will, of course, leave the seals in that bearing and there is even room for an oil seal. But that would be pointless, since I'm sure I'll get some weepage though the spacer/axle flat area. But a small amount will lube the sprockets and chain. I'm thinking the level in the motor housing will determin how much finds it's way out..
Once I get the bearing, I'll run it on the stand[my bike up-side down actually]and see how it works out[literaly].
I guess the down side is, if the oil level gets low, bye bye motor bearing[I ordered some extras].
Later, when I get a sensored motor on the frt., I can pull the Halls on this one, run some larger phase wires and see if a 1000 Watt mini can't be reliable. Then maybe a little "snake oil" might pay off.

 

[GCinDC]

unoiled motor got to 70C quickly on first uphill, then was more or less flat/downhill until 7 min uphill section, after which i had to pedal unoiled motor to keep it from overheating...

video of CA/temp sensor mostly synched:
[youtube]5TIAJqYbAWk[/youtube]
ride map again w/ unoiled temps listed:

 

[hjns]

Very good information! Any thought on how quickly the motor returns to ambient when oiled? Anyway, with 60-70oC there is no reason to look....

 

[GCinDC]

Any thought on how quickly the motor returns to ambient when oiled?

a while, but i think it's faster while moving under gentle current than sitting!

any harm in running the motor w/o oil now? if i wanted to collect more data w/o oil, for example? will the residual ATF dry out, harden, gunk up?

i managed to get my rear brake pads operational again after soaking and wiping with paper towels and isopropyl alcohol, so that's good...

it seems like figuring out how to waterproof (oilproof) the slot is going to be my next challenge:

i'm thinking the sealant around the outer ring of the bearing, to keep oil from getting between the bearing and the side cover.

then for the slot itself, since the bearing will be seated in the sidecover, should i put sealant in the empty slot, and then slide on the sidecover?

 

[bigmoose]

Looks like your bearing is "shielded" and not "sealed" ... that will give a path for oil leakage once the grease dissolves a bit.