BLDC Motor 1

[ghadar]

What can be the side effect of placing a thin Aluminium tube (1mm) between the stator and the armature?

 

[Skogsgurra]

Three (or four) that I can think of:

1 You will get extra losses due to eddy currents in the Al. Can be quite significant.

2 You will reduce capacitive coupling from stator winding to rotor and yhus reduce bearing EDM. You have to make the Al conact the stator iron for that.

3 Less mechanical tolerance left for rotor excentricity and bending.

4 Internal circulation may be hindered.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[Clyde38]

Will the tube rotate with the rotor or be stationary with the stator?

 

[ghadar]

The Aluminium sleeve (tube) is stationary with the armature.

 

[sreid]

The aluminum sleeve will form an eddy current brake from the rotating rotor permanent magnet field. This creates a back torque on the rotor.

What are you trying to accomplish?

 

[ghadar]

I'm trying to capsulate the volume between the rotor and armature, the rotor is submerge in liquid and armature in air.

 

[sreid]

Then I'd think plastic or ceramic. Is there some reason you can't completely submerge the motor with fluid contacting everything?

 

[ghadar]

It will jeopardize the secondary perpose of the mechanism.

Plastic will work most probably more as coating or casting in production, more difficult to achieve these thickneses for prototpe.

Thanks for your advice

 

[electricuwe]

This kind of design, either a metal tube or a some kind of plastic, is used in pumps for HVAC. I remember to have seen some designs like that from Wilo,

http://www.wilo.de.

Can't remember if it was on their website or in one of their patents.

If you need to put metal in between I would recommend to use stainless steel, non magnetic and quite low conductivity.