Electric motor repair - ebmpapst R2E180-AV82-15

[letthesmokeout]

Hi.
I have an Extraflame Lucrezia Idro Steel pellet stove, and the smoke fan is an ebmpapst R2E180-AV82-15:

Relevant previous posts:
https://www.eevblog.com/forum/repair/how-to-test-an-ebm-papst-r2e-motor/

Symptoms:
1) When the motor is cold, the stove will start but the motor has a mechanical noise coming from it that sounds bad.
This noise can be 'screeching' and intermittent.

2) The stove runs for a few minutes but then the motor begins to warm and it loses speed and eventually stops.

3) The stove has an rpm sensor and notices rpm=0 so it gives GAS FAIL error and turns off.

4) It doesn't cut power to the motor though, which gets hotter and has a buzzing coming form it.

5) Unfortunately, it has probably been left sitting stationary like this for at least 3 times at around 5 minutes each time.

6) The motor doesn't have any burnt smell coming from it and it seemed to be getting warm but not really hot.
Although I did not let it sit for the full cooling cycle.

7) The motor can be moved manually with ease.

My diagnosis:
1) The motor probably has bad bearing(s), and the capacitor or main board has a fault.

My Solution:
1) Open motor and replace bearings.
Replace capacitor and hope main board is ok.
It does look ok, like it has kept all its smoke inside:


Problem:
1) I can't figure out how to open the motor.
On a youtube video of a similar unit, there is a circ clip holding the motor together (around 3mins) :
https://youtu.be/jvCR6PaBoVA?t=178

My motor has a second metal tube/spacer that I can't remove:

I tried tapping it out in a vice but it didn't budge.
I did not try heating it as that seems like asking for trouble.
It doesn't seem like it screws out.
My guess is that it was pressed on and is ceased on it, which makes me not so hopeful of getting it off without destroying the motor.

I emailed ebmpapst for disassembly instructions and they said:
"Unfortunately ebmpapst do not supply disassembly instructions for their products as all fans & blowers are supplied as complete balanced units.."

Extraflame want me just to buy a new motor at €460.

And so, dear internet, you see why I am here.
If you could answer the following I would be most grateful:
Q1) Am I on the right track with replacing the bearings and capacitor?
Q2) How do I open the motor?

***sorry I can't get the images inline***

[florentbr]

If the motor turns without effort and doesn't feel like there's sand in the bearing, then it's likely fine.

It's a single phase induction motor. You can test it by plugging it directly to main.
If it runs correctly without heating, then you'll know the issue is not the motor.
A bad capacitor would prevent the motor from starting.
You can check the capacitance with a multimeter, it should be around 2uF (written on motor).

If the motor runs fine alone, then the issue is from the board.
I don't see any DC rectifier stage, so the speed is likely controlled by a phase controlled circuit with triacs.

https://blog.orientalmotor.com/speed-control-basics-speed-control-methods-of-ac-induction-motors

Could be that one of the triac is shorted. This would create an imbalance at lower speed.
Check Q4 and his friends.

[letthesmokeout]

Thanks for the reply.
Here is a link to a video of the motor noise when it is running in the stove:
https://drive.google.com/file/d/1WcCVZJq-8_iDlEXPzQYryIaN53YtHVTh/view?usp=sharing


When the motor is removed from the stove it doesn't feel obvious like sand in it spinning by hand.
The max speed of these is around 2600-2700 rpm.

I'll test the motor on the bench this evening and get back to you.

[strawberry]

dry bearing (lubricant turned into hard rock) seems sliding bearings go bad like this

[letthesmokeout]

Hi,
Here is a video of the motor starting up and running on the bench:
https://drive.google.com/file/d/1d4P64FclSxmsFaYtldm8izfelBAFpU0L/view?usp=sharing

It starts with a lot of noise and quietens after a while.
It does not get hot though, even after running for 4-5 minutes.
I tried it a couple times and it seems to start fine, so maybe the capacitor is ok but the bearings are an issue.

I suppose there are other problems like the triacs as mentioned earlier to explain the problem of it stopping after a while in the stove?

[florentbr]

The bearings need to be replaced.
The heat is probably due to the added friction at lower speed.
It could have stopped due to over-current or because it failed to reach the targeted speed.
I would first fix the motor and check that the amperage is under 0.31A at full speed.
If you really can't access/replace the bearings, try a silicone lubricant spray.

[strawberry]

replacement is not possible without some workshop ( is not ball bearing)

[wasedadoc]

My motor has a second metal tube/spacer that I can't remove:
(Attachment Link) (Attachment Link) (Attachment Link)
I tried tapping it out in a vice but it didn't budge.
I did not try heating it as that seems like asking for trouble.
It doesn't seem like it screws out.

Reverse thread?

[letthesmokeout]

It turns out the bushing is not threaded onto the shaft.
Unfortunately the  bushing was ceased on the shaft.
I let it soak with WD40 overnight, but the bushing was just too tight on the shaft.
I had to use a lot of heat and a lot of force to remove it.
It was very difficult to remove even with heat.
Also, I had to grind off the rear bearing which inevitably resulting in some grinding on the motor shaft which is not good.
I assume these motors are balanced and tapping, heating and grinding on the shaft is probably a very bad idea.
And throughout I am assuming I haven't cooked the windings by heating the bushing and shaft...

I bought replacement bearings and will put the motor back together as a backup.

I have decided to buy a new motor for the pellet stove.
The best price I found was €210 including shipping, at:
(They ship to Ireland)
https://www.grelettrofiamma.it/it/estrattore-ventola-fumi-re180-av82-15-16-thermorossi-h2o-mcz-laminox-lucrezia-extraflame/?linkid=

I posted on an Italian site where many people have successfully replaced bearings in this motor:
(I used google translate - I don't speak Italian)
https://stufapellet.forumcommunity.net/?t=62618314

My conclusion is that these motors can be taken apart, but if the bushing is ceased you really are in trouble.
If you have access to an engineering company or electric motor refurbishment company, perhaps they can press off the bushing with a special press.

If you have a metal shop you could fabricate something to help press off the bushing.
( i.e. use tens of thousands of euros worth of gear to fix a motor worth a few hundred euros...)

I don't have access to any of this gear.
Armed with an angle grinder, hammer, blow torch, vise grips and vice I was able to remove the bushing.
The bushing is heavily scratched and I left grind marks on the shaft.
(A die grinder would be much better than an angle grinder here)
I would advise against this course of action.

I also had to tap pretty hard to get the bushing off, and this has probably distorted the shaft a little.
The shaft is pretty thin and hard and I don't like the amount of force I used on it.
Although to the naked eye it looks fine.

I will put the old motor back together and see if it runs ok.
But since the motor is essential to the pellet stove, I will install a new one in the stove.

So a sad ending to the story, but it often goes this way with gear that is not designed with repair in mind.
And I fully admit that I don't have the tools or experience to remove this bushing in a non-destructive way.

Thanks to everyone for their replies.

[BILLPOD]

Does the new motor have any provisions for lubricating the bushings periodically?  I had a motor in a shop-vac with bushings like yours and they failed in a similar fashion.  Taking careful and extensive measurements, I was able to find ball bearings to replace the bushings.  A couple drops of machine oil every so often and no more bushing problems. 

[CaptDon]

Our tape transports and cart machines at the radio station used these inside-out Papst motors mainly for capstan drive where the motor shaft itself was carefully machined to be the capstan. Indeed they have ball bearings and the spinning portion of the motor actually hung by a c-clip from the upper bearing. the c-clip was only as big as the rotating portion of the inner diameter of the bearing, there was no mechanical interference to any stationary part. We had to replace the bearings with 'Instrument Grade' bearings as regular ball bearings of the same size generated huge amounts of mechanical noise. Many times if we suffered a power failure and the motors came to a complete stop before power was restored the motors would not self start again indicating it was past time for a bearing set replacement. We had dozens of cart machines and the motors were always spinning even if the machine was not actively in use.