Patent Application
20100258377
1. Field of the Invention
The present invention relates generally to acoustic systems, and in particular, to acoustics systems for computing machines.
2. Background Information
Computing systems with rack drawers for computing devices are designed primarily for data center environments. As such, computing systems require a significant amount of airflow in order to maintain an acceptable internal operating temperature. However, air moving devices, such as fans and blowers, generate a level of noise that is unacceptable in an office environment compared with data centers.
An acoustic cooling apparatus for a computing system. One embodiment of the acoustic cooling apparatus comprises a cooling muffler comprising sidewalls and an endwall, the sidewalls being substantially parallel to each other, each sidewall being substantially perpendicular to the endwall at one end, the walls forming an enclosure having an open end opposing the endwall. Each sidewall includes an exhaust opening. At least a portion of the interior of each wall of the enclosure is covered by sound absorbing material for attenuating air cooling sound.
Substantially the entire interior of each wall of the enclosure may be covered by sound absorbing material selected based on the frequency of air cooling sound being attenuated. The sound absorbing material may be selected in thickness, porosity and material type for attenuating cooling sound entering said open end, allowing the cooling sound energy to penetrate the sound absorbing material, compressing the sound absorbing material at a microscopic level. The sound absorbing material may be selected to allow the cooling sound energy to penetrate into the sound absorbing material, causing recoil of the sound absorbing material and pulling back on the sound absorbing material being compressed by the sound energy, thereby canceling some of the sound energy by converting it to heat.
The acoustic cooling apparatus may comprise four rectangular sidewalls and a square endwall, the sidewalls being substantially parallel to each other, each sidewall being substantially perpendicular to the endwall at one end and connected to a side of the endwall square, the walls forming an enclosure having a square open end opposing the endwall.
Other aspects and advantages of the present invention will become apparent from the following detailed description, which, when taken in conjunction with the drawings, illustrate by way of example the principles of the invention.
For a fuller understanding of the nature and advantages of the invention, as well as a preferred mode of use, reference should be made to the following detailed description read in conjunction with the accompanying drawings, in which:
The following description is made for the purpose of illustrating the general principles of the invention and is not meant to limit the inventive concepts claimed herein. Further, particular features described herein can be used in combination with other described features in each of the various possible combinations and permutations. Unless otherwise specifically defined herein, all terms are to be given their broadest possible interpretation including meanings implied from the specification as well as meanings understood by those skilled in the art and/or as defined in dictionaries, treatises, etc.
The description may disclose several preferred embodiments of an acoustic cooling apparatus as well as operation and/or component parts thereof. While the following description will be described in terms of acoustic devices in computing systems, it should be kept in mind that the teachings herein may have broad application to all types of systems, devices and applications.
One embodiment involves an acoustic apparatus that blocks the direct line of sight to noise generating devices while presenting a low impedance plenum with sufficient air flow. Referring to
The interior side surfaces (i.e., interior of sidewalls 3b and endwall 6) of the door/plenum 1 are lined with the acoustic foam 4 to prevent reflected noise from exiting exhaust openings 3a on four sidewalls 3b of the muffler door 1. The exhaust openings 3c are positioned on the top, bottom, left and right surfaces of the acoustic door 1 on the sidewalls 3b. When the door 1 is connected to a device 1a at the opening 6a, air from a cooling fan in the device 1a enters the opening 6a and exits through the sidewall exhaust openings (vents) 3a.
The muffler door 1 has a depth 3 that creates a plenum chamber 2 sufficient as to not cause an impedance of airflow from the device 1a. A notch 3c in the bottom wall of the door 1 coincides with a pair of bridge lances located at the bottom rear of the device 1a. The notch 3c allows the door 1 to easily open and close around managed cables (attached to bridge lances using tie-wraps, cable ties, Velcro straps, etc.), providing power and communication to devices installed in the device 1a.
Positioning the exhaust openings 3a on the top, bottom, left and right surfaces of the acoustic door 1 on the sidewalls 3b, allows air to freely exit the plenum chamber 2 (
The parallel surfaces of the interior of the sidewalls 3b of the manifold door 1 deflect/bounce noise sound waves back and forth to each other causing sound energy loss, converting the energy into heat, while the remaining amount of sound bounces back from the endwall 6, as shown in
Stiffness/density of the walls 3b, 6 of the door (enclosure) 1 are selected such that the resonant frequencies of the enclosure 1 are dampened and/or are moved outside the fan noise energy frequency range, preventing excitation of the fan noise frequencies. The walls can be made from metal, plastics, and other materials.
The acoustic foam 4 is selected in thickness, porosity and material type in damping fan noise. The fan energy lies in a finite frequency band. The foam porosity/air gap size is selected accordingly. Preferably, the foam 4 is selected such that the fan sound energy penetrates the foam 4, compressing the foam 4 at a microscopic level, such that as the energy penetrates deeper into the foam 4 the initial foam begins to recoil, pulling back on the foam 4 that is currently being compressed by the noise energy, thereby canceling some of the sound energy by converting it to heat. For example the foam 4 may be about one inch thick for the inside face of the sidewalls 3b and about 1.5 inches thick on the inside face of the endwall 6. The foam may be cell polyurethane type M.
Depth 3 of the acoustical door 1 allows for more occurrence of the sound energy to impact the foam 4, wherein each time some noise energy is converted to heat, some noise is reflected back to an inside face of the parallel surface 3b. From a thermal standpoint, the depth 3 is selected such that the fan exhaust air turbulence is reduced before it is directed out the side exhaust openings 3a.
The manifold door 1 prevents increasing static pressure downstream of the air moving devices 1a. In one example, the open area to airflow ratio is greater than or equal to 0.005 ft2/CFM in addition to a minimum depth of 0.5 ft, reducing airflow turbulence and velocity without increasing static pressure.
A combination of sides/top/bottom exhaust outlets 3a accommodates inadvertent blockage of one side (e.g., if the side of the unit is placed against a wall). The door 1 can accommodate the airflow (and attenuate the noise) of various rack optimized computing units that fits in a rack (e.g., a 19′ wide rack). The acoustic muffler door may be hinged, making a latching door that easily allows access to rear cable connections modules in the device 1a. In one example, the door 1 attenuates the acoustic levels of an installed system to general office acoustic sound levels of 6.5 Bels (or less), without impeding airflow in a way that causes overheating.
While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art.
