What happens if you spin a leaf engine >20.000 RPM

[Zapatero]

In the name of the science of all power thirsty poeple i sacrificed my motor. The good news are though that Johannes and me sucessfully found a way to increase the power of the leaf engine significantly. But the first software i tested didn't have the RPM limiter implemented and i thought: "What should happen? Just don't spin it too much".
But when tuning the parameters i played with syncadv to further increase the power in the upper RPMs, which i did sucessfully. But the way the pedal behaved was different from now on - it somehow barely reacted until i pressed it to approximately 2/3 of all the way and then it suddenly send a full throttle signal. I was stuck in traffic for a while then i had the most stupid idea: I pressed the pedal with no gear in over that certain point and the motor suddenly spun up all the way. It was a terrible noise and from then on it didn't work anymore.

I then started to look for the failure and found this:

[Zapatero]

When overspinning the engine something must have broke and from then on i guess it was a chain reaction. It seems that the two halfes of the magnet have twisted a bit:

Now i've cut the shaft of the magnet and cut our the temperature sensor to send this to Johannes as a test bench for the resolver and the temp-sensor.

If you ever wanted to know where the temp sensor actually is located - it's on the rear end and not far into the motor:

[arber333]

As far as i deared to go was 15000rpm and i was scared as hell at 180km/h. I leave it at 165km/h now that i am more confident. I simpatize with you though...

EDIT: Maybe we would need to implement a sort of maxRPM limit for inverter to limit torque to when exceeded?

[SuperV8]

When overspinning the engine something must have broke and from then on i guess it was a chain reaction. It seems that the two halfes of the magnet have twisted a bit:

PXL_20211001_085806598.jpg


Now i've cut the shaft of the magnet and cut our the temperature sensor to send this to Johannes as a test bench for the resolver and the temp-sensor.

PXL_20211001_092444482.jpg
PXL_20211001_093436179.jpg
PXL_20211001_093429811.jpg


If you ever wanted to know where the temp sensor actually is located - it's on the rear end and not far into the motor:
PXL_20211001_093359440.jpg

The offset shape on the rotor is normal.

That rotor has contacted the stator - not normal! to do this it has either bent (unlikely) or the bearings have failed (more likely) The bearing looks a little blue - is this true of the photo?

Can you report the numbers on the bearings? and you can usually look up maximum RPM's.

[SKB123]

Thank you for sharing - Failure is key to success

interested to hear more on "successfully found a way to increase the power of the leaf engine significantly"

[EV_Builder]

De motor isn't supported in the middle, only on the extremes.
So if you go to really high rpm's you should see the mechanical forces pulling it out of the centre.

The middle is where it will bend like a chord and thats where it started to touch and self destruct...
RPM limit is a must on the same levels as amp limit.

[johu]

Just for everyone's peace of mind:
There is an rpm limit (fmax), it just happened to not work in the experimental version that he tested. The bug is fixed in 5.12.R and it was never in any released version.

[SuperV8]

De motor isn't supported in the middle, only on the extremes.
So if you go to really high rpm's you should see the mechanical forces pulling it out of the centre.

The middle is where it will bend like a chord and thats where it started to touch and self destruct...
RPM limit is a must on the same levels as amp limit.

Or the rotor will expand with high rpm's - maybe a carbon fibre sleeve (Tesla Plaid) would help!

[SuperV8]

This is an interesting article regarding the Leaf motor and bearings.

Quote:
"The main bearing at the motor shaft gear is a ball bearing, oil lubricated from the gearbox lubricant. It has similar geometry to a
6207 ball bearing which specifies a maximum speed of 11,000 rpm for oil lubricated operation. This
matches well with the maximum stated speed of the LEAF of 10,400 rpm"

https://info.ornl.gov/sites/publication ... b46325.pdf

For a 6207 bearing SKF list 13,000rpm limiting/mechanical & 20,000rpm maximum thermal in optimum conditions.
Your bearing looked a little blue, could have got a bit hot? Does it feel slack/rough?
Has anyone 'hot rodded' and EV motor by fitting better bearings I wonder?

[EV_Builder]

This is an interesting article regarding the Leaf motor and bearings.

Quote:
"The main bearing at the motor shaft gear is a ball bearing, oil lubricated from the gearbox lubricant. It has similar geometry to a
6207 ball bearing which specifies a maximum speed of 11,000 rpm for oil lubricated operation. This
matches well with the maximum stated speed of the LEAF of 10,400 rpm"

https://info.ornl.gov/sites/publication ... b46325.pdf

For a 6207 bearing SKF list 13,000rpm limiting/mechanical & 20,000rpm maximum thermal in optimum conditions.
Your bearing looked a little blue, could have got a bit hot? Does it feel slack/rough?
Has anyone 'hot rodded' and EV motor by fitting better bearings I wonder?

The problem is the rotor; in the middle it will bend. 20.000rpm isn't nothing! You need to remove weight and make it stiffer for that.
or give it a bearing in the middle to halve its span.

[SuperV8]

This is an interesting article regarding the Leaf motor and bearings.

Quote:
"The main bearing at the motor shaft gear is a ball bearing, oil lubricated from the gearbox lubricant. It has similar geometry to a
6207 ball bearing which specifies a maximum speed of 11,000 rpm for oil lubricated operation. This
matches well with the maximum stated speed of the LEAF of 10,400 rpm"

https://info.ornl.gov/sites/publication ... b46325.pdf

For a 6207 bearing SKF list 13,000rpm limiting/mechanical & 20,000rpm maximum thermal in optimum conditions.
Your bearing looked a little blue, could have got a bit hot? Does it feel slack/rough?
Has anyone 'hot rodded' and EV motor by fitting better bearings I wonder?

The problem is the rotor; in the middle it will bend. 20.000rpm isn't nothing! You need to remove weight and make it stiffer for that.
or give it a bearing in the middle to halve its span.

I agree the rotor could bend - but there would need to be a large out of balance force applied, but also if this failure was due to a bending rotor (like a cord or skipping rope) I would also expect it to have only contacted the stator at one point and have a small/confined witness mark on the rotor - not all the war around.

The damage/witness mark on the rotor from the photos looks fairly circumferential to me which suggests either bearing failure or rotor diameter expansion due to high centrifugal forces.

[celeron55]

What if, if we say the rotor bent, it then got some friction with the stator (obviously), and it started to roll along the stator like a wheel? That would make it get a circumferential mark.

[EV_Builder]

What if, if we say the rotor bent, it then got some friction with the stator (obviously), and it started to roll along the stator like a wheel? That would make it get a circumferential mark.

exactly and if the material is softer then the one it touches the surface will increase. not saying the bearing liked this exercise but the play of the bearing would be always there...

[Arlin]

In the name of the science of all power thirsty poeple i sacrificed my motor. The good news are though that Johannes and me sucessfully found a way to increase the power of the leaf engine significantly. But the first software i tested didn't have the RPM limiter implemented and i thought: "What should happen? Just don't spin it too much".
But when tuning the parameters i played with syncadv to further increase the power in the upper RPMs, which i did sucessfully. But the way the pedal behaved was different from now on - it somehow barely reacted until i pressed it to approximately 2/3 of all the way and then it suddenly send a full throttle signal. I was stuck in traffic for a while then i had the most stupid idea: I pressed the pedal with no gear in over that certain point and the motor suddenly spun up all the way. It was a terrible noise and from then on it didn't work anymore.

I then started to look for the failure and found this:

Did you get a log of the max RPM reached? Or did you have a gauge or anything?
Im asking because I want to know the max I can spin mine to. I have been spinning them to 15k for drag racing. And I am planning to spin one up 500rpm at a time to find where it explodes.

Would be great to have more data.

-Arlin

[Zapatero]

Did you get a log of the max RPM reached? Or did you have a gauge or anything?
Im asking because I want to know the max I can spin mine to. I have been spinning them to 15k for drag racing. And I am planning to spin one up 500rpm at a time to find where it explodes.

Would be great to have more data.

-Arlin

Unfortunately the logger was not turned on at this time, but according to the noise i've heard it was beyond 20.000. But of course this is just a guess.

The damage/witness mark on the rotor from the photos looks fairly circumferential to me which suggests either bearing failure or rotor diameter expansion due to high centrifugal forces.

The bearings where totally fine, no excess play at all. The rotor must have expanded in the middle.

[Tremelune]

I suspect it's not one particular speed, but a combination of speed, heat, and load.

Does anyone have anecdata about what the currently believe "safe" speed is? My Mini's top speed is limited to maybe 65mph due to the 10k limit.