What are the specific reasons for the mechanical noise of miniature DC motors ? The following article introduces it to everyone.
There are many reasons for the vibration and noise of miniature DC motors, which can be roughly attributed to mechanical noise and electromagnetic noise. Here mainly talk about mechanical noise and the causes of mechanical noise:
First, bearing noise. Due to the improper size matching between the bearing and the bearing chamber, noise is generated when the miniature DC motor rotor rotates together. Balls that are not round or have internal debris cause them to collide with each other to produce vibration and noise. The improper value of the bearing's preload will cause noise on the raceway surface.
Second, the noise caused by the rotor imbalance.
Third, the noise caused by eccentric assembly.
The following methods should be adopted to reduce the mechanical noise of miniature DC motors:
First, sealed bearings should generally be used to prevent debris from entering.
2. When the bearing is assembled, it should be demagnetized and cleaned to remove oil and iron debris. Bearings after cleaning are generally less noisy than bearings before cleaning. The grease must be clean and free of dust and impurities.
Third, the cooperation between the outer ring of the bearing and the bearing chamber, the inner ring and the shaft should not be too tight. The cooperation between the bearing outer ring and the bearing chamber should have a radial clearance within a certain range.
Fourth, in order to eliminate the axial clearance of the rotor, appropriate pressure must be applied to the bearing. Generally, a wave spring washer or a three-point elastic washer is used, and it is suitable to be placed on the shaft extension end.
Fifth, use the weight removal method or weight method to correct the rotor imbalance.
6. The buffer material is filled between the magnetic steel and the output shaft, which can absorb the small vibration generated by the rotor during the commutation process, while avoiding the rigid connection between the output shaft and the external load, and transmitting the external vibration to the magnetic steel, which affects the rotation caused by the excitation. Moment mutation. Prevent air noise caused by resonance between rotation frequency and load.
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