Why Does the Planetary Gear Motor Make Noise？

Last time, I introduced the speed ratio calculation method of planetary gear boxes in speed reduction motors to friends. Today, I want to share with you why planetary speed reduction motors generate noise.

When micro planetary motors are running, they usually make some noise, which is a very common phenomenon. However, some planetary speed reduction motors have relatively large noise, while some planetary speed reduction motors have very small noise. What is the reason for this? Let's take a closer look.

During the operation of a planetary speed reducer, the bearing will generate natural vibration, which resonates with the material of the micromotor components. The axial gas spring constant of the bearing causes axial vibration of the rotor. If the lubrication is poor, friction noise will occur, especially for large planetary speed reducers. If the lubrication is poor, the friction noise will be even greater.

The friction between the brush and the commutator of a planetary gear motor can also produce certain noises, which are not obvious in micro motors. There is also the hydrodynamic noise of planetary gear motors, and there is no way to prevent the natural ventilation noise caused by the rotor, which is particularly evident in large planetary gear motors.

Electromagnetic noise from planetary speed reduction motors, noise generated by electromagnetic force waves caused by unbalanced or unbalanced magnetic circuits shaking the air gap, or magnetic noise caused by saturation of magnetic flux density or eccentricity of the air gap.

Electromagnetic noise of micromotors. After the micromotor is powered on, the air gap magnetic field acts on the stator and rotor core, generating fundamental magnetic potential and a series of harmonic magnetic potentials. The fundamental magnetic potential generates tangential force and electromagnetic torque. The interaction of harmonic magnetic fields generates radial forces that vary over time and space, and these radial forces act on the core. The radial force generated by low magnetic harmonics is relatively large, causing periodic vibration of the iron core in the radial direction, which is the main source of electromagnetic noise. Therefore, suppressing low harmonic components can effectively reduce electromagnetic noise.

In fact, for micro planetary speed reduction motors, the noise can be very small. Generally, the noise of micro speed reduction motors is controlled within 50 db, and the noise is mostly large planetary speed reduction motors. Before production, the micro motors have been designed to reduce noise. Moreover, during the application process, they are installed inside the product and the environmental noise during use, so the noise of the micro motors has no impact at all, unless they are operated in a very quiet environment, To hear very small noises.