What is NVH in air conditioning industry?

CLING builds up its national-advanced modern laboratory in accordance with the international standards, focusing on innovation, comprehensive abilities, and the “Semi anechoic room for NVH noise test” is just one of the top-notch labs.

The word “NVH” is the abbreviation of “Noise, vibration and harshness”, it evaluates vehicle noise, vibration and comfort, and to be concise, the sense of touch, hearing and even visual perception of passengers in the vehicle belongs to the scope of NVH research. To the passengers, hearing is the second most important sense, where visual perception accounts the most, so the impact of NVH on passengers is most direct and prominent.

When people become more concerned about environment protection and the need for comfort riding, along with the development of air conditioning technology, the NVH performance faces more challenges. CLING’s NVH lab is exactly built to catering for the noise analysis of A/C assembly and it’s parts including condenser fans, evaporator blowers, defrosters, etc.

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CLING NVH lab function

Dynamic signal spectrum analysis:

The measurement range is 20-20KHz. FFT can achieve 512, 1024, 2048 to 65536 points without zoom function to realize frequency refinement.

Time (s) - sound pressure level (DB) curve:

Automatically and synchronously record the variation curve of prototype noise with time, and record the sound pressure level varying with temperature and pressure. Through the analysis of the variation law of sound pressure level, it can be used not only for sound source evaluation, but also for sound source identification.

Sound post-processing:

The test sound can be recorded in the whole process, and then the sound data can be processed and analyzed offline.

Multichannel analysis:

At most six sensors are set for testing, which can be applied to structural modal analysis, sound recognition, sound insulation test, sound absorption coefficient test, muffler transmission loss, pressure pulsation transmission, etc.

Vibration test:

Equipped with vibration sensor, it can test the vibration speed, displacement, acceleration, etc. of the unit.

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NVH semi anechoic room

In order not to be disturbed by the external environment during the test, CLING has a semi anechoic room, its internal effective size is 10000mm long ×6800mm wide × 4700mm high, the ceiling of the semi anechoic chamber and four walls are equipped with sound-absorbing wedges, and the suspended floor is adopted. The floor is separated from the foundation by a layer of damping shock absorber to ensure long-term stable acoustic performance parameters and provide a low-noise test environment of semi free field. The test environment can reach the background noise L0 ≤ 12.5db (A), the cut-off frequency of free sound field F0 ≤ 100Hz, and the natural frequency of spring vibration isolation system f ≤ 7Hz.