Cooler running motor & waterproof

[shenzhen_ex]

There is an existing industrial process that creates a cooler running motor, improves environmental protection, and upgrades the mechanical strength of electrical motors.

This process is one of the highest industry standards for electric motor encapsulation. The process is called VPI; (Vacuum Pressure Impregnation). This process is only used in a small number of the world’s electric motor production and is primarily applied on extreme heavy duty/ adverse environment applications.

Vacuum pressure impregnation is a process in which vacuum and pressure are used to assist the penetration of liquids into devices. It is often used to impregnate electrical apparatus with resin (we use Loctite Resinol RTC Porosity Sealant). The result is a void free solid where there once were voids at the stator coil windings and stator core laminations.

BENEFITS (cut and paste from some non-confidential documents.)
Strengthens the insulation system and extends service life.
Eliminates the dead air spaces that cause hot spots within coils.
Provides a low thermal resistance path that lowers temperatures.
Creates a repellent to oily substances, moisture, and chemical contaminants.
Resin becomes a sealant against environmental conditions and creates bonds for good mechanical strength.
Reduces mechanical vibrations.
Reduces the audible noise level.
Enhances the dielectric capability, which allows for higher voltage stress levels without failure.
Reduces coil movement.

 

[e-beach]

Hmmmmm......assuming a hub motor, how do you seal at the axle so not to decompress?

 

[shenzhen_ex]

Hmmmmm......assuming a hub motor, how do you seal at the axle so not to decompress?

In mass production the axle would be assembled after the wound stater went through the VPI process.

For my motors i think i would just take the side covers off and let the resin go everywhere. It only fills all the voids, the rest just gets rinsed off the outside.


I am actually not sure why you used the term 'decompress". the entire motor wound stator would be put in the vacuum / pressure vessel to gets its voids filled with resin.

 

[knighty]

I can't see it being much of an advantage for you?

only advantage I can see is keeping water/muck out of the windings, which might be nice if you're air cooled.... but then the filler is going to insulate the stator too ?

 

[shenzhen_ex]

I can't see it being much of an advantage for you?

only advantage I can see is keeping water/muck out of the windings, which might be nice if you're air cooled.... but then the filler is going to insulate the stator too ?

Research of this process indicates that is has 2 primary purposes.
(1) Improve heat transfer
(2) Improve environmental protection.

So do you think the "void-less" winding will dissipate heat better than the solid block of resin and copper?

Some resin will be drawn between the magnetic iron lamination of the stator but the magnetic field is apparently improved.

 

[knighty]

Research of this process indicates that is has 2 primary purposes.
(1) Improve heat transfer
(2) Improve environmental protection.
So do you think the "void-less" winding will dissipate heat better than the solid block of resin and copper?
Some resin will be drawn between the magnetic iron lamination of the stator but the magnetic field is apparently improved.

I was thinking air directly onto the windings is better than air to resin to windings cooling, also the windings will have a larger surface area than the resin

 

[shenzhen_ex]

Research of this process indicates that is has 2 primary purposes.
(1) Improve heat transfer
(2) Improve environmental protection.
So do you think the "void-less" winding will dissipate heat better than the solid block of resin and copper?
Some resin will be drawn between the magnetic iron lamination of the stator but the magnetic field is apparently improved.

I was thinking air directly onto the windings is better than air to resin to windings cooling, also the windings will have a larger surface area than the resin

So you don't think that the heat conductivity from the windings to the core is improved by filling up the stator slot clearance with resin, rather you think that the air gaps are better conductors? Is that right?

 

[knighty]

wait... I thought you were talking about an air cooled motor ?

I assumed you were talking about an air cooled motor where the resin would give protection from water/grit etc... and let you send loads of air through the motor

if you're just going to leave the case sides closed up I don't think the resin will make much difference at all, heat will conduct away from the windings to the core much much quicker through the metal stator parts than through the resin

also, even if you manage to conduct all the heat into the core.... when where does it go ? the axle isn't great for heat loss

more heat is lost from the stator conducting that heat to the air in the motor, that air heating up the case (+magnets etc..) and then that heat conducting out from the case sides

 

[shenzhen_ex]

if you're just going to leave the case sides closed up I don't think the resin will make much difference at all, heat will conduct away from the windings to the core much much quicker through the metal stator parts than through the resin

I think the case could be covered with holes since the coil would be sealed in the resin.

even if you manage to conduct all the heat into the core.... when where does it go ? the axle isn't great for heat loss

I really don't have the answer. I do know that VPI processes are used by big motor companies for the thermal dissipation and environmental protection, when economically feasible. I also believe that hub motor companies here (in China) would never invest in expensive VPI equipment/consumables no mater how good it was.