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Method for dual fan cooling with active acoustic monitoring and control

IP.com Disclosure Number: IPCOM000083113D
Publication Date: 2005-Feb-28
Document File: 4 page(s) / 29K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for dual fan cooling with active acoustic monitoring and control. Benefits include improved functionality, improved performance, and improved thermal performance.

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Method for dual fan cooling with active acoustic monitoring and control

Disclosed is a method for dual fan cooling with active acoustic monitoring and control.  Benefits include improved functionality, improved performance, and improved thermal performance.

Background

      More effective heat dissipation from heatsinks implies a requirement for increased airflow.                       

The conventional two-fan cooling solution runs two fans simultaneously, generating a single sound signature. Improved cooling is achieved but results in increased noise, which is highly undesirable in desktop and other systems and is subject to European regulatory limitations (see Figure 1).

              To conventionally solve the cooling/noise problem, several solutions are in use, including:

•             Higher aspect-ratio heatsink fins

•             Increased heatsink size and a single fan

•             Liquid cooling

•             Thermoelectric cooling

•             Noise canceling achieved by a sound generator emitting a sound signature tuned to cancel out that of the target noise source

•             Noise dampening achieved by using acoustically insulating materials or padding moving parts against vibration

      Next generation cooling systems, such as thermoelectric coolers, refrigeration, and multiphase coolers are expensive.

General description

      The disclosed method is a feedback and control system integrated into a dual-fan arrangement around a heatsink. A sound sensor monitors the fan’s acoustic output. When preset levels are exceeded, a control signal is sent to interrupt or augment one fan’s power supply, driving its sound signature out of phase with the other fan. This out-of-phase condition prevents the sound wave peaks from aligning and increasing the sound amplitude. Instead, the frequency is doubled at the same or a minimally increased amplitude. This solution provides the cooling benefits of two fans within the acoustic budget of a single fan.

              The key elements of the disclosed method include:

•             Two fans mounted in series on the opposite sides of a heatsink airflow path so the air travels across the heatsink at high velocity

•             Sound level sensor located near the cooling solution

•             Logic circuit to receive sound level data from the sound sensor, compare it to a preset limit, and output a control signal to the fan-speed throttling mechanism

•             Fan speed throttling circuit for momentary or sustained fan-speed adjustment.

Advantages

              The disclosed method provides advantages, including:
•             Improved functionality due to providing a logic circuit to regulate the fan speed and noise level
•             Improved performance due to improving the thermal performance without the increased noise levels that typically result from a dual fan solution

•             Improved thermal performance due to achieving a higher velocity or volume of airflow across a...