In order to ensure that the rotor can rotate freely in the stator cavity during motor operation, an air gap must be maintained between the rotor core and the stator core. Although there is no direct electromagnetic connection between the rotor and stator, when the stator winding is energized, similar to the principle of a transformer, there is an electromagnetic connection between the rotor and stator, thus achieving the energy conversion function between electrical energy and mechanical energy.

There should be an air gap between the rotor and stator of the motor, mainly for the following reasons:

1、Ensure the rotor rotates freely

In order to ensure that the rotor can rotate freely inside the stator cavity during motor operation, an air gap must be maintained between the rotor core and the stator core. In this way, there will be no friction between the rotor and stator due to direct contact, ensuring the normal operation of the motor.

2、Realize electromagnetic connection and energy conversion

Although there is no direct electromagnetic connection between the rotor and stator, when the stator winding is energized, similar to the principle of a transformer, an electromagnetic connection is established between the rotor and stator. This electromagnetic connection enables energy conversion between electrical and mechanical energy, thereby driving the motor to operate.

3、Affects motor performance and operational reliability

The size of the air gap has a significant impact on the performance and operational reliability of asynchronous motors

·Excessive air gap: will lead to a significant increase in magnetic resistance, excitation loss, and excitation current, resulting in a decrease in the power factor of the motor and deterioration of its performance. At the same time, excessive air gap can cause the motor to operate unstably, generate significant noise and vibration, have adverse effects on the installation environment, and accelerate the wear of components. In addition, due to low electromagnetic conversion efficiency and large internal losses of the motor, it can cause the temperature of the motor to rise too quickly, affecting its service life.

·Too small air gap: It will increase the harmonic magnetic field in the air gap, increase the stray losses and noise of the motor, and reduce the maximum torque and starting torque. In addition, a too small air gap can easily cause the rotor and stator to rub against each other during operation, resulting in a sweeping phenomenon and making it difficult to start, thereby reducing the reliability of operation and making assembly difficult.

4、Reasonable range of air gap

The air gap of a typical small asynchronous motor is about 0.251.5mm, while the air gap of a medium-sized asynchronous motor is about 0.752mm. This range is determined based on the design requirements and operating conditions of the motor to ensure good performance and operational reliability of the motor.

In summary, there should be an air gap between the rotor and stator of a motor to ensure free rotation of the rotor, achieve electromagnetic connection and energy conversion, affect motor performance and operational reliability, and meet the reasonable range requirements of the air gap.

Hengda Electric has always been dedicated to the research and development, production, and service of various types of motors. With advanced technology and equipment, lean manufacturing processes, reliable product quality, and satisfactory after-sales service, the company provides customers with the most suitable motor professional solutions and creates greater social value.