What are the brushes of the motor? The role of the brush

What is the brush of the motor

A motor brush is a device that transmits energy or signals between the stationary and rotating parts of a rotating machine such as a motor or generator. Also called carbon brush. Carbon brushes are generally made of pure carbon and coagulant. They are generally square in shape and are stuck on a metal bracket. There are springs inside to press them on the rotating shaft. For example, after oil drilling is completed, it needs to be tested.

The role of the brush:

1. The external current (excitation current) is applied to the rotating rotor through the brush (input current);

2. Introduce the static charge on the large shaft into the ground (grounding brush) through the brush (output current);

3. Change the current direction (in the commutator motor, the brush also plays a commutation role);

4. Lead the large shaft (ground) to the protection device for rotor grounding protection and measure the positive and negative voltage of the rotor to ground.

The role of the brush: The brush is an important component of the motor, responsible for conducting current between the rotating parts and the stationary parts.

1. According to the hardness of the material, it can be divided into soft brushes, medium-hard brushes and hard brushes.

2. According to the objects of use of brushes, it can be divided into brushes for steam turbine generators, brushes for rolling steel motors, brushes for traction motors, brushes for automobile tractors, brushes for power tools, and electricity for aircraft motors.

3. According to the color of the brush, it is divided into black brush (made of pure carbon graphite material) and colored brush (made of copper and other metal materials and graphite).

4. According to the different brush materials, it can be divided into: graphite brushes; electrochemical graphite brushes; metal graphite brushes.

The requirements of the motor for the brush are:

1. On the surface of the commutator or collector ring, a suitable surface film composed of cuprous oxide, test ink and moisture can be formed.

2. The service life of the brush is long, and the wear on the commutator or the collector ring is small.

3. The brush has good electrical conductivity and strong overload capacity.

4. The electric power loss and mechanical loss of the brush are small.

5. There is no spark that is harmful to the motor under the brush.

6. The noise of the brush operation is small.