Dismantling and repairing the motor :o

[bob2.0]

After 9 years, when I had melted the phase wires, the magnets of my QS60V5000W were totaly rusty.
My stator had a lot of scratches, but it never felt like it was sticking together.
I sanded both with sandpaper grit 240 and 1000 and put clear laquer onto them, installed thicker phase wires with higher rated temperature isolation and a temperature sensor and raised the controller limits.

20220802_172535.jpg
20220803_163019.jpg

Thank you, I suppose it is 'reassuring' to see this happens and the motor lives!

It makes me wonder more if there is a bearing tolerance issue, and the axle has sagged a bit, and is running tilted. Or may be it is some of that, and also the rust under that magnet has lifted it.

I will figure this out. I think those things are manageable, but I have some anomalies with the windings too.

Before I dive into that, I'll take off the other cover plate and inspect both sides of the windings.

If you have any tips on how to remove the other cover plate off its bearing, I'd be grateful, thanks.

[dominik]

As it was easy to open my QS60V5000W motor, there was only little sealing at the cover, I opened the second and good motor I had just to have a look insight.

The one with less copper was sold in an 8kw scooter and had slightly bigger magnets 45mm instead of 40mm in the 5kW QS

[MEroller]

It makes me wonder more if there is a bearing tolerance issue, and the axle has sagged a bit, and is running tilted.

Worn-out bearings made one of my 5kW erider Motors go zingzing ever stronger, so I replaced it with my second motor and took it apart. I took the stator to a friend with a big lathe in his shed, and stuck the stator in there, gripping the axle. And lo and behold, the stator itself was off-center by about 1 mm, and who would have believed it, the highest point had the scratches from the hitting magnets!
We turned away the excentric shape, turning it into a true centric stator. After that came the coating with clear coat to inhibit corrosion, a set of new bearings and seals, and I put the motor back together. The now even, though slightly larger airgap gave the motor audibly and feelably more grunt, so that was a 100% successful endeavor

[bob2.0]

I now mention the 3rd anomaly I have seen in my motor.

I notice now, on the photograph close up at the bottom of page 3 of this thread, these details;

WhatsApp Image 2025-01-27 at 21.32.03.jpeg (54.72 KiB) 353 mal betrachtet

WhatsApp Image 2025-01-27 at 21.32.31.jpeg (102.77 KiB) 353 mal betrachtet

I looked again because I also have these features, and I wonder if they are a short, and where the enamel has melted? These photographs are from my motor;

Are these shorts, or another problem? Or, normal?

[bob2.0]

It makes me wonder more if there is a bearing tolerance issue, and the axle has sagged a bit, and is running tilted.

Worn-out bearings made one of my 5kW erider Motors go zingzing ever stronger, so I replaced it with my second motor and took it apart. I took the stator to a friend with a big lathe in his shed, and stuck the stator in there, gripping the axle. And lo and behold, the stator itself was off-center by about 1 mm, and who would have believed it, the highest point had the scratches from the hitting magnets!
We turned away the excentric shape, turning it into a true centric stator. After that came the coating with clear coat to inhibit corrosion, a set of new bearings and seals, and I put the motor back together. The now even, though slightly larger airgap gave the motor audibly and feelably more grunt, so that was a 100% successful endeavor

Thank you for that encouragement.

Can you turn it easily, without the laminations bending and twisting? I guess you did!

I will measure both the magnet radial position and the rotor.

I think there will always be both, neither magnets nor rotor can be perfect radius. Then the largest part of the inner may touch the smallest part of the outer.

(Perhaps it is easier to make an accurate air gap with axial flux motors?)

A bigger gap will mean faster? But only a little extra gap. It is field weakening without the waste of current?

[MEroller]

We were VERY careful with the turning, only taking 1/10th of mm off at a time, then a little more. Only the most outward lamination loosened slightly.
The slightly bigger gap caused more torque, not more speed. Possibly because it increased the "hunger" of the magnetic field, more than was lost in field strength.

[bob2.0]

We were VERY careful with the turning, only taking 1/10th of mm off at a time, then a little more. Only the most outward lamination loosened slightly.
The slightly bigger gap caused more torque, not more speed. Possibly because it increased the "hunger" of the magnetic field, more than was lost in field strength.

I can get the grinding wheel out ...

[bob2.0]

I briefly measured the parts with my digital verniers.

The diagonal distance between the magnets seems very uniform, to small fractions of a mm. However, it might be off-set, I will do more measurements, but the worn magnet does not seem higher than those around it. I am confused why it is just one that has worn, then?

I wonder if water has pooled around that end of the magnet and the wear was from rust with the stator, until it had gone.

But, why does it still bind?

The stator dimensions seem less accurate, I can measure large fractions of a mm difference.

The bearings appear to not have any radial play I can detect. They are only 'RS' bearings but seem to be OK, and seal OK.

I was thinking to replace with NTN LLU for the improved sealing, which are now being made in the higher tolerance 'CM' grade, and the LLU has double sealing which says it is good to inhibit moisture ingress.

But, please tell me, how have you got the other side plate off? Like the one I released, it seems to be a little corroded in place. I do not want to hammer the plate from the inside, I did try, and I am more likely just to damage it.

[jeff-jordan]

Now, looking at your pictures, I'm wondering how the axle and stator are fixed together.

I'm just asking because I have the issue that every time the torque direction has to change (in case of driving backwards, or recuperation braking), I can hear a "tschack" sound from the motor (that's why I actually disabled EABS).
So there must be some free play or clearance between my axle and the stator.

[bob2.0]

I guess maybe a woodruff key? I can take the circlip off to see what is underneath it on the shaft, if you like?