Dc cooling fan noise source and introduction
air-cooled radiator working noise there are three main sources: bearing friction and vibration, the vibration of the blade, wind noise.
the first point. The vibration of the blade: generally made of plastic fan blade has a certain toughness, can withstand a certain degree of physical deformation, also in the process of pushing air because of mechanical vibration, but generally small. Another serious vibration is due to the blade quality distribution, center of mass and rotation axis eccentricity. When the door leaf area ( Quality) Or eccentricity larger cases, may drive the fan and radiator overall vibration occurs, and then spread to the whole case. In the event of such a phenomenon, should doubt fan quality and working condition.
the second point. Bearing friction and vibration: not only the noise, and impact performance, shorten the device life, reduce the efficiency of energy utilization, is as far as possible to solve the key technical problems in product design.
the third point. Wind: the flow of air between blunt talk to each other, with the surrounding objects, friction, and the separation of blade for air, periodic supply air pulse power, etc. , will produce noise. The faster the air velocity, turbulence, the more often wind noise is bigger, and will increase with the increase of wind speed in acceleration. Common in axial flow fan blades and the space between the casing outside the joints of the flyback airflow, produce a wind noise at the same time, more can cause adverse effect to air flow, is also in the flange, side into the wind, such as improved design
noise is introduced:
noise is the main influence is reflected in the user's physical and mental health and safety, accompanied with noise and vibration may lead to wear and interface chip loose platter, scratches and so on the phenomenon of using threatening.
so when choosing the fan, we should focus on the fan work noise, for nature is as small as possible. But manufacturers in product parameters provided by the noise data, often have a certain gap with the actual use of the effect, not directly with the accurate, this is mainly due to the standard test methods and actual use environment there is a difference.
1. First, the background noise of daily life is much higher than 15 dba of background noise on the quiet room. General city, residential area near the traffic trunk road, background noise in the middle of the night between 30 ~ 35 dba, whereas daytime in 40 ~ 50 dba.
2. Second, quiet interior wall material with sound-absorbing, sound insulation effect, Yu Jinfeng side measurement cannot reflect the fan sends out the sound pressure of airflow, and the actual use of the user is unable to avoid.
3. Furthermore, fan work alone and install to work on the radiator noise difference is huge. Experienced users know: air cooled radiator high-speed most of the noise from air flow through the radiator fins were produced by the wind noise and rubs, the fan itself accounts for only small part of noise. Most of the radiator along with noise also is only the fan noise working alone, rather than the whole work noise, the manufacturer does not specify a little misleading.
4. In addition, the distance between the user and the radiator fan in practical use are generally within 1 m, if we consider the case of sound insulation effect, the echo of the small room, particular case is difficult to determine. Of course, this is a test of any 'standardised' cannot solve the problem, users can only suggest to reduce the noise damage does not affect to use at the same time try to widen and the distance between the noise source, choose sound insulation effect better case, when the room is decorated with sound-absorbing materials.
as a result, in order to closer to the user in the actual use of the state, with the OCER. Net consistent profound, rigorous principle, when we tested air cooled radiator, conclude a set of noise test standard:
1. Ambient noise less than 35 dba, namely the daily life to achieve minimum levels of sound level;
2. Test for air cooled radiator as a whole, such as fan speed control or similar function is measured at the time of maximum and minimum speed noise sound level;
3. Air cooled radiator above rubber cushions, maintain 50 cm, with the sound level meter distance between without any shelter, reverse (away from the walls No soft adornment material) 50 cm, the other side more than 3 m away from the walls;
use this set of standards can guarantee: users in practical use, as long as not special circumstances, such as resonance, foreign bodies, blocking needed to endure the noise sound level of the highest water product is more than the measured values.
above is dc fan noise source and introduction, hope to be of help, if you need a cooling fan, etc. , please feel free to contact us: http://www. xfs— 风扇。 com/