After testing and analysis, we know that the radiated sound pressure on the bottom of the oxygen concentrator is the largest, because this place is where the compressor is installed, and the bottom shell is vibrated to radiate the sound pressure mainly concentrated on the bottom. Therefore, the following measures can be used to solve this problem.
1. Solve by way of sound absorption. Install gypsum board on the inner wall of the bottom surface of the oxygen generator to absorb the radiation noise. We generally control the thickness of the gypsum board at 2-4mm, which can greatly improve the absorption capacity of high-frequency noise.
2. Ways of damping and vibration reduction. At the place where the radiated noise on the side of the shell is greatest, damping bands and damping materials should be installed to increase the vibration attenuation function.
3. Solve by way of sound insulation. Coat the whole shell with sound insulation material to reduce the efficiency of radiation.
4. Constrain the damping. Use the damping steel plate shell structure, fill the damping glue in the middle, and block the gaps in each part of the oxygen generator, which can effectively reduce the radiation noise of the shell.
Through the above measures, after optimizing the noise propagation path, after testing, the sound pressure of the high frequency part has been well controlled. But the low frequency part of the radiation is still very large. This is because of the coupling of the vibration noise of the oil-free compressor and the air noise of the solenoid valve. So further work lies in the control of coupled noise sources.