Fan noise and Solutions

Fan noise and Solutions

1、系统阻抗

1, the system impedance

一个机壳的入风口与出风口之间范围占全部系统阻抗的60%至80%，另外气流愈大，噪音相对愈高。系统阻抗愈高，冷却所需的气流愈大，因此为了将噪音降至最小，系统阻抗必须减至最低程度。

A case of the inlet and the outlet of all system impedance range between 60% to 80%, and air flow is, the higher the relative noise. The system impedance is high, the cooling air required more and more big, therefore in order to minimize the noise, the system impedance must be reduced to the lowest level.

2、气流扰乱

2, the airflow disturbance

沿着气流路径所遇到的阻碍而造成的扰流会产生噪音。因此任何阻碍，特别在关键的入风口与出风口范围，必须避免，以降低 噪音。

Caused along the flow path of the obstacles of the disturbed flow generated noise. Therefore, any obstacle, especially in the critical inlet and outlet area, must avoid, in order to reduce the noise.

3、风扇转速与尺寸

3, the fan speed and size

由于高转速风扇比低转速风扇产生较大的噪音，因此应尽可能尝试及选用低转速风扇。而一个尺寸较大、转速较低的风扇，通常比小尺寸、高转速的风扇，在输送相同风量时安静。

Because of the high speed fan produces greater noise than a low speed fan, should therefore be possible to try and use low speed fan. While the fan is a large size, low speed, small size, high is usually higher than the fan speed, air volume in conveying the same quiet.

4、温度升高

4, temperature rise

一个系统内，冷却所需的风量与允许的温升成反比。允许温升稍微提高，即可大量减少所需的风量。因此，如果对强加之允许温升的限制略微放松一些，所需风量将可降低，噪音亦可降低。

A system, cooling the air volume needed and the permissible temperature Shengcheng inverse. Allowable temperature rise slightly improved, can reduce the number of required air volume. Therefore, if some relaxation of restrictions on the permissible temperature rise slightly, the required air volume will be reduced, the noise can be reduced.

5、振动

5, vibration

有些情形，整个系统的重量很轻，或系统必须按照某种规定方式运作时，特别建议采用柔软的隔绝器材，以避免风扇振动的传递。

In some cases, the entire system is light in weight, or system must be a specified mode of operation according to the recommendations, especially by soft contact equipment, to avoid the transfer of fan vibration.

6、电压变动

6, the voltage variation

电压变动会影响噪音程度。加到风扇的电压愈高，因转速升高，振动就愈大，产生的噪音也愈大。

Voltage change will affect the noise level. Voltage is applied to the fan is higher, because the speed increased, the larger the vibration, noise is also more.

7、设计的考虑

7, design considerations

构成风扇的每一零件设计，均会影响噪音程度。下列设计的考虑可达成降低噪音：绕线铁心的尺寸，扇叶与外框的设计及精确的制造与平衡。

Design of each part of fan, will affect the noise level. The following design considerations can reduce noise: the winding core size, design of blades and the frame and precise manufacturing and balance.

怎样选择风扇

How to choose a fan

所有需要使用风扇散热的电机与电子产品的设计工程师，必须决定一个特定系统散热所需的风量，而所需的风量取决于了解系统的耗电量及是否能带走足够的热量，以预防系统过热的情形发生。事实显示，系统的使用年限会由于冷却系统的不足而降低，所以设计工程师也应该明白，系统的销售量与价格，可能因为系统的使用年限不符使用者的预期而下降。

Design Engineer all require the use of cooling fan motor and electronic products, we must determine a specific system cooling air quantity required, and the power consumption of the air volume needed depends on the understanding of the system and is able to take in enough calories, to prevent overheating in the system situation occurs. The fact shows, system service life will be decreased because of insufficient cooling system, so the design engineer should also understand, volume and price system, because the system does not match the expected service life of the user declines.

选择正确的通风组件，请考虑下列目标：

Selection of ventilation components correctly, please consider the following objectives:

1、最好的空气流动效率

1, the best air flow efficiency

2、最小的适合尺寸

For 2, the smallest size

3、最小的噪音

3, the minimum noise

4、最小的耗电量

4, the minimum power consumption

5、最大的可靠度与使用寿命

5, the maximum reliability and service life

6,The total cost of 6, reasonable