Commutator

The commutator includes: mechanical commutator, semi-plastic commutator, and all-plastic commutator. The commutator used in automobile starter mainly uses mechanical arch commutator and plastic commutator.

The principle is that when the coil passes through the current, it will rotate under the action of the permanent magnet through the attraction and repulsion forces. When it turns to balance with the magnet, the original energized wire will be the same as the contact on the corresponding commutator. The brushes are separated, and the brushes are connected to the contact pads corresponding to the set of coils that generate the driving force.

If there is no function of the commutator, the motor can only be stuck in less than half a turn, and it can only be used as an electric brake. The centrifugal force generated when the motor rotates is used as the driving force to control the size of the starting resistance, so as to reduce the starting current of the motor and increase the starting torque, so that the wound asynchronous motor can realize the brushless automatic control operation. It is mainly composed of casing, starting fluid, moving plate, spring, terminal, safety valve, exhaust valve, etc. The liquid resistance starting has the characteristics of small starting current, large starting torque, automatically adapting to changes in power supply and load, and protecting the motor. It has always been operated under rated parameters, but the welding port of the rotor winding and the commutator rising piece is the weak link of the commutator rotor, and the traditional soldering process is used, combined with the measurement results of the DC resistance between the pieces, to judge the rotor. The welding point between the winding and the riser of the commutator is loose, resulting in fatigue of the end wire, increasing the contact resistance, increasing the calorific value, accelerating the oxidation of the contact surface, further increasing the contact resistance, and further increasing the calorific value. Such a vicious cycle then causes the commutator rotor insulation to burn out at high temperatures, arc discharge to the ground, and damage the commutator. The results of the dismantling inspection of the commutator show that the test data and judgment conclusions of the rotor windings are accurate. In addition to transmitting longitudinal current, the motor commutator also has the task of current commutation in the short-circuit armature coil.

These currents are the reverse currents and reactance voltages generated by the main current motor commutator, which cause edge sparks and arcs when the brushes slide on the surface of the motor commutator. The influence of the motor commutator on the motor performance depends on It is the process of realizing the circuit conduction when it slides with the brush at a relatively high speed under certain premise. Although the description of this process is relatively complicated, and the theoretical research is still in development, through the comparative analysis of the operating conditions of micro-motors at home and abroad, it is possible to It was determined that wear was the pivotal factor that caused the change in contact resistance.