Function and classification of motor brush

1、 Function of brush

In various fields of national economy, motors are widely used in industry, agriculture, transportation and other aspects. Around 1889, the brush began to be used in the motor. It plays the role of exporting or importing current in the motor. In the commutator motor, the brush also plays the role of commutation. Today, with the rapid development of motor industry, the manufacturing technology of motor brushes is becoming more and more perfect, the performance is significantly improved, and the varieties are increasing day by day. There are many new high-performance brushes. Although the brush is small and cheap, it plays a very important role in the motor, which is often compared to the heart of the motor.

Brushes are divided into brushes and carbon brushes. Their function is to conduct current between the fixed parts of the motor and the rotating parts - commutator or collector ring. Brushes are widely used in large, medium and small synchronous motors, generators, small electric tools, DC motors and other equipment. The objects in direct contact with them are slip rings or commutators. Reasonable selection and matching of them can improve the reliability of motor work.

2、 Classification of brushes

1. Classification by raw materials

Brushes can be divided into carbon brushes and metal brushes according to different raw materials. Carbon brushes are mainly made of general carbon materials such as carbon black, graphite or coke. Metal brushes are mainly made of copper powder, silver powder or other metal materials and graphite, which are generally called metal graphite brushes or metal brushes. Compared with metal brushes, carbon brushes have a long service life, but the noise will be relatively large. The noise of metal brush is relatively small, but its service life is relatively short.

2. Classification by purpose

It is quite difficult to classify brushes by purpose. This is because the motors using brushes include motors and generators, DC and AC, large and small, and are used under different rotating speed, commutation characteristics, current and voltage. Therefore, it is difficult to classify brushes uniformly according to their purpose. In addition, the characteristics of various brushes also fluctuate in a large range with the manufacturing conditions (mainly the ratio of raw materials). Therefore, it is not appropriate to limit the adaptability of a specific series of brushes.