The Structure Of The DC Motor

The structure of the DC motor should be composed of two parts: the stator and the rotor. The stationary part of the DC motor is called the stator. The main function of the stator is to generate a magnetic field. The part that rotates during operation is called the rotor. Its main function is to generate electromagnetic torque and induced electromotive force. It is the hub for the energy conversion of the DC motor, so it is usually called the armature. Constructor and fan, etc.

Stator

(1) Main magnetic pole

The role of the main pole is to generate an air gap magnetic field. The main magnetic pole is composed of the main magnetic pole iron core and the excitation winding. The iron core is generally made of 0.5mm~1.5mm thick silicon steel plate punching and riveting. It is divided into two parts: the pole body and the pole shoe. The upper part of the excitation winding is called the pole body, and the lower part is called the pole body. The pole shoe is wider than the pole body, which can not only adjust the distribution of the magnetic field in the air gap, but also facilitate the fixing of the excitation winding. The excitation winding is made of insulated copper wire and is sleeved on the core of the main magnetic pole. The entire main magnetic pole is fixed on the base with screws.

(2) Commutation pole

The function of the commutation pole is to improve the commutation and reduce the commutation spark that may be generated between the brush and the commutator when the motor is running. It is generally installed between two adjacent main magnetic poles. composed of pole windings. The commutating pole winding is made of insulated wire and is sleeved on the commutating pole iron core. The number of commutating poles is equal to that of the main magnetic pole.

(3) Machine base

The housing of the motor stator is called the frame. The base has two functions:

First, it is used to fix the main magnetic pole, commutation pole and end cover, and to support and fix the entire motor;

The second is that the base itself is also a part of the magnetic circuit, which constitutes the magnetic path between the magnetic poles, and the part through which the magnetic flux passes is called the yoke. In order to ensure that the machine base has sufficient mechanical strength and good magnetic permeability, it is generally made of steel castings or welded steel plates.

(4) Brush device

Brush devices are used to introduce or extract DC voltage and DC current. The brush device consists of a brush, a brush holder, a brush rod and a brush rod seat. The brush is placed in the brush holder and pressed with a spring, so that there is a good sliding contact between the brush and the commutator. The brush holder is fixed on the brush rod, and the brush rod is mounted on the circular brush rod seat. must be insulated. The brush rod seat is installed on the end cover or the inner cover of the bearing, the circumferential position can be adjusted, and it is fixed after adjustment.

Rotor

(1) Armature core

The armature core is the main part of the main magnetic circuit, and is also used to embed the armature winding. Generally, the armature iron core is made of punched sheets made of 0.5mm thick silicon steel sheets and laminated to reduce the eddy current loss and hysteresis loss generated in the armature iron core when the motor is running. The stacked iron core is fixed on the rotating shaft or rotor bracket. The outer circle of the iron core is provided with an armature slot, and the armature winding is embedded in the slot.

(2) Armature winding

The function of the armature winding is to generate electromagnetic torque and induced electromotive force, and it is the key component of the energy conversion of the DC motor, so it is called the armature. It is composed of many coils (hereinafter referred to as components) connected according to certain rules. The coils are wound with high-strength enameled wires or glass-coated flat copper wires. The coil sides of different coils are embedded in the armature slot in two layers. There must be proper insulation between the iron cores and between the upper and lower coil sides. In order to prevent the centrifugal force from throwing the coil edge out of the slot, the slot is fixed with a slot wedge. The termination portion of the coil extending out of the slot is bound with a thermosetting weft-free glass tape.

(3) Commutator

In the DC motor, the commutator is equipped with brushes, which can convert the external DC power into the alternating current in the armature coil, so that the direction of the electromagnetic torque is constant; in the DC generator, the commutator is equipped with The brush can convert the alternating electromotive force induced in the armature coil into the direct current electromotive force drawn from the positive and negative brushes. The commutator is a cylinder composed of many commutator segments, and the commutator segments are insulated with mica sheets.

(4) Rotary shaft

The rotating shaft plays the role of supporting the rotation of the rotor, and needs to have a certain mechanical strength and rigidity, and is generally made of round steel.