Disclosed is a method that modulates the spacing of the blades on a fan to reduce or change the characteristics of fan noise. Benefits include effecting the noise output without impacting the cost of the fan.

Background

There is a need to reduce the excessive noise and unpleasant pitches that are produced by the fans used to cool a system. Current fans use spacing between the fans blades equal to 360° divided by the number of blades (see Figure 1). The following are currently used to reduce fan noise and pitch:

§         Modifying the impeller shape

§         Modifying the fan spoke shape

§         Modifying the surface that interfaces with the fan (i.e. the heat sink interface shape)

§         Modifying the specifications to allow more noise

§         Using variable speed fans

General Description

The disclosed method varies the spacing of blades on a fan in order to alter or reduce fan noise and pitch (see Figure 2). This approach is based on a NASA program that reduced helicopter noise by modulating blade spacing.

Advantages

The disclosed method reduces the amount of fan noise, and/or changes the pitch of the fan to a more pleasant tone, without impacting the cost of the fan.

Fig. 1

Fig. 2

Disclosed anonymously