Motor aerodynamic noise control
Fan noise control. Due to the space limitation, the fan in the motor cannot be equipped with some additional components to improve its efficiency, and the efficiency is much lower than that of the industrial fan, and the noise is higher. In principle, reducing motor ventilation noise can be done by reducing air volume, reducing windage, increasing efficiency (starting with fan types, etc.), and possibly reducing fan diameter and speed. Such as: (1) fan blades with uneven spacing fan blades with uneven spacing, can reduce the regular pressure disturbance intensity caused by uniformity; (2) fan blades with porous materials; (3) with special fans - Rotor coupling. The fan of the variable speed motor supplies sufficient cooling air at a low speed, and the air is excessively cooled at a high speed, thereby increasing aerodynamic noise. With the rotor coupling, the fan speed can be kept constant.
Control of aerodynamic noise. In medium and large motors, whistle noise can be generated by cooling air through axially aligned stator and rotor ducts; an effective way to reduce this noise is to place sound absorbing material near the radial air duct opening of the stator.
The whistle noise can also be caused by other reasons such as the gap between the rotor bar of the high speed induction motor and the end of the stator winding. With a closed or closed-circuit ventilation system, the main noise can be reduced by 20dB or more. However, it is considered that due to the reflection of the cover wall, the sound pressure level in the cover will be higher than the value at the same point when there is no cover.
Control of noise at the air inlet and outlet. A muffler made of sound absorbing material to reduce the dynamic noise at the air inlet and outlet is very effective in many cases. China's medium-sized new series of motors, the power per unit mass has been greatly improved, so the flow of cooling air must be increased. Intensive ventilation will inevitably lead to an increase in motor ventilation noise. To this end, a muffler is installed on the upper part of the box-type anti-drip medium-sized high-voltage motor.
Reprinted from the network