A bearing, the outer bearing ring, during which the rolling elements such as balls or rollers and other parts of the holder, relative movement between them, the relative movement between elements of the impact on irregular Noises. So bearing sound often distributed over a wide frequency band, low-frequency portion of the inner and outer eccentric or irregular, or rolling elements arranged in irregular spots and other precision rotation effect, causing the rotation frequency or frequency noise and vibration. High frequency portion by a rolling contact bearing raceway and the rolling surface, that the surface of the road and surface damage caused corrugated, often in the range of 1 ~ 5KHz frequency, peak at 2kHz or more in the frequency 3kHz, this bearing sound frequency speed has little to do, but the size was increased with the speed. Described above are related to the quality of the bearing itself, the noise generated.

     Often find the same quality in a different batch of bearings mounted on the motor, the measured bearing noise varies widely, indicating that the motor bearing noise and the structure and assembly process itself, a great relationship. First, file size precision rotor bearing and end caps bearing chamber size will affect the accuracy of the bearing with precision, thereby changing the size of the bearing radial clearance, the radial clearance is too small or too Metropolitan adverse noise and vibration. Rotor bearing profiles and precision bearing chamber cover lower tolerance band wide, and bearing the original clearance associated upper and lower limits larger motor noise will cause instability. In addition, the impact of the bearing assembly process is also great, should be kept clean bearings, bearings installed Euparagonimus process should pay attention, not mixed with debris and grease fill quantity to the right. Poor motor cover also cause stiffness bearing noise increased.