The stator-rotor air gap is a necessary parameter for motor products, and different series of products have different requirements for air gap. The air gap of asynchronous motors is relatively small, and the size of the air gap has a greater impact on the no-load current of the motor. In order to effectively control the size of the no-load current, the stator-rotor air gap of the motor will be controlled to a minimum, the purpose of which is to improve the power factor of the motor; however, in view of the comprehensive factors of motor operation reliability and production manufacturing level, and taking into account the deformation and coaxiality deviation of the motor shaft, end cover, base, core and other matching parts, the air gap of the motor will be appropriately enlarged based on theoretical calculations.
For the air gap of asynchronous motors, relevant motor literature provides empirical calculation formulas; for the convenience of description, we use the code “δ” to represent the air gap of the motor, with the unit of mm; the code “D” to represent the inner diameter of the motor stator core, with the unit of mm; the number of motor pole pairs is represented by “P”, and the length of the motor core is represented by “L”. After calculation according to the relevant formula, the data is rounded according to the relevant rules.
For small-sized motors with a rated power not exceeding 30 kW, the air gap length of a 2-pole motor is calculated according to formula (1), and the air gap length of a 4-pole and 12-pole motor is calculated according to formula (2).
From the above formula, we can see that the air gap between the stator and rotor of a small-sized motor is about 0.2 to 0.3 mm. For large and medium-sized motors, due to the relatively large size of the motor, the absolute value of the stator and rotor air gap is larger, roughly above 0.5 mm; from the relevant calculation formula, we can also find that the air gap of a high-speed motor is larger than that of a low-speed motor.
Post time: Apr-15-2025