What's a "brushless" fan?

[AmberClad]

This has been bothering me for a good while, so I figured I finally ask. What exactly is a brushless fan? Or a brushed fan for that matter? I've looked at the labels on my various different case fans, and all of them are brushless. I don't know that I've ever seen a brushed fan...

 

[Gneisenau]

In a brushed motor, brushes (similar to paint brushes or more comonly soft metal bars.) contact the armature and allow electricity to flow into it to create a magnetic field. The magnetic field of the amrature opposes the magnetic field generated by the stator windings surrounding the armature. This is what causes the motor to spin. (Basically) As the armature spins, the brushes contact a different set of windings on the armature altering the magnetic field in it so it continually opposes the stator winding fields.

In a brushless motor, the armature windings are replace with permanent magnet and the roles of the armature and stator are reversed. The brushless motor requires an electronic controller to determine where the armature is in it's rotation with respect to the stator windings so it can alter the magnetic field of the stator windings to keep the armature spining.

A brushless motor is more costly to make, usually more powerful, lasts longer,but simpler mechanically to make.

 

[VinDSL]

Never really thought about it, but the only place I've NOTICED brushes is on heavy-duty apps, like hand tools, automotive starters, et cetera...

 

[covert24]

yea and in r/c cars they have brush motors. The only bad thing about brush motors is that the brushes eventually wear out and you either need to buy new ones or just replace the entire tool/motor itself.