Solution

1. When selecting the motor model or type, the following technical parameters should be determined first:

Working time per day, start and stop times and interval time, unidirectional or bidirectional operation, working torque T, output speed n, ambient temperature, heat dissipation conditions of the installation location, etc.

2. The selection method and steps of the motor model or type are as follows:

① According to the load characteristics, determine the rated voltage, output power, torque and speed of the motor shaft extension (1), the service life of the motor, mainly the life of the brush, and determine the diameter of the shaft extension, the connection method, and the installation method;

② Determine whether the shaft extension end needs to be sealed, and whether the material of the shaft has special requirements;

③ The power of the motor is mainly related to the inner diameter of the stator (4) ΦDa and the rotor core (3) L. These two parameters also basically determine the outer diameter and total length of the motor;

④ Considering the application of the motor, determine the protection level of the motor, the sealing method between the end cover (1), the stator (4), and the brush cover (5), the surface protection method, and the lead wire (6). way out;

⑤. Determine the working system of the motor according to the working mode of the load, which will affect the size, outer diameter and total length of the motor;

⑥. The DC motor can be equipped with reducers, brakes and encoders as required to meet different operating conditions;

3. Understanding the following knowledge and principles can make motor selection more accurate and fast

① Power density

The power of a DC motor is the product of its speed and torque. Since the DC motor is limited by the performance of the magnetically conductive material, the magnetic field of the motor is in the same range, so the power density mainly depends on the speed of the DC motor, which is different from the speed of the DC motor. The main factor of power density, by increasing the speed, higher power density can be obtained. By optimizing the design, the power density of the permanent magnet DC motor can reach 0.4KW/Kg.

② Efficiency

The efficiency of a DC motor is also related to the size and speed of the motor. The maximum efficiency of a small DC motor is generally around 72%-82%. For a small DC motor running in one direction, the maximum efficiency can reach more than 85%.

③ Torque

The torque is related to the volume of the motor. Generally, the output torque of a small DC motor is 0.01Nm-10Nm. The gear reducer can be selected according to the user's needs to reduce the motor speed and increase the output torque.

④ Speed

The speed is related to the load of the motor. For the same motor, the larger the torque, the smaller the speed. Torque and speed are two very important parameters when selecting a motor. The maximum speed of a DC motor can be increased by more than 10000r/min. The output speed of the motor can also be reduced by means of reducers with different speed ratios.

⑤ Precision

Prompt: What is the range and error of the motor that Shanbo can make? How can we detect and control the accuracy to provide customers with qualified products

The DC motor has good voltage characteristics and torque speed characteristics. Generally, its speed error range under a certain torque is not more than ±8%; if there is a requirement for position high precision, an optional encoder can be installed according to the user's needs. Accuracy is determined by sensor and controller control accuracy. A brake can also be added to the motor, which is suitable for emergency braking.