The role of carbon brushes in impact drill motors

The role of the impact drill carbon brush is to send the excitation current generated by the excitation generator to the rotor coil. The principle of impact drilling electricity is that after the magnetic field cuts the wire, a current is generated in the wire. The generator uses the method of rotating the magnetic field to cut the wire. The rotating magnetic field is the rotor, and the cut wire is the stator. In order for the rotor to generate a magnetic field, an excitation current must be input to the coil of the rotor, and the carbon brush plays this role.

In fact, the "brush" here refers to carbon brushes. Impact drills generally use DC motors. Brushed impact drills use brushed motors, which need to be commutated through brushes. The carbon brush is commutated by a Hall sensor and driven by a driver to rotate.

     Compared with brushless impact drills, brushed impact drills mainly have the following advantages and disadvantages:

Advantages: The brushed impact drill starts quickly, brakes timely, smooth speed regulation, simple control, simple structure, cheap price, and it has a large starting current, large torque (rotation force) at low speed, and can carry a heavy load.

Disadvantages: Due to the friction between the carbon brush and the commutator, the impact drill with a brush is prone to sparks, heat, noise, electromagnetic interference to the external environment, and low efficiency and short life; carbon brushes are consumables, after a period of time, it will be replaced, which is troublesome.