I have recently torn down the air blower of a car (for cleaning).

I was wondering what is the name (and purpose) of the parts shown on the picture :

enter image description here

It looks like a copper wire wrapped around a (magnetic?) cylinder. Is it a solenoid? I don't think it's brushes (which are above head of first arrow). This is not specific to my car, I have googled for other car blower pictures and this seems to be common.

Also (another question) is there a reason for most car manufacturers to use brushed motors instead of brushless ones for air blowers? It create tons of black dust (as shown on the picture) and they wear pretty quickly.


That looks like a Behr blower motor as used in BMW etc.

The coils are inductors (wire wrapped around a ferrite rod core) for EMI filtering so the fan motor won't muck up the AM radio reception etc.

Brushed motors are used because they are cheaper (including the controller). Life is not really a big deal in cars- figure if the average speed is 30mph and the car lasts 60,000 miles for the original owner, that's only 2000 hours of operation, and the fan may not be used for all of that.

My experience is that they last around 100,000 km (60,000 miles) on average.

  • \$\begingroup\$ The coils are inductors (wire wrapped around a ferrite rod core) for EMI filtering aren't motor windings inductors themselves ? \$\endgroup\$
    – tigrou
    Dec 15 '16 at 18:09
  • 2
    \$\begingroup\$ Yes, but they are on the other side of the commutator, so the arcing occurs across the commutator. IIRC there are shunt capacitors (radial?) along with the series inductors. \$\endgroup\$ Dec 15 '16 at 18:26
  • \$\begingroup\$ Are you sure they are not the brush springs? There needs to be something to maintain pressure of the brush on the commutator. If they were for EMC there would be a capacitor as well. \$\endgroup\$ Dec 15 '16 at 22:38
  • \$\begingroup\$ @KevinWhite Definitely not- I changed this kind of motor out not long ago. Here is a side view: \$\endgroup\$ Dec 15 '16 at 23:31

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