EP-4741728-A1 - ACOUSTIC ATTENUATION DEVICE FOR TELECOMMUNICATIONS CABINETS

EP4741728A1EP 4741728 A1EP4741728 A1EP 4741728A1EP-4741728-A1

Abstract

The present application is directed to an acoustic attenuation device adapted for use in a telecommunications cabinet. The device includes a housing, a volume matrix having a main body divided into a plurality of chambers, an aperture plate having a plurality of opening arrangements, each opening arrangement aligned with a respective chamber of the volume matrix, a pressure plate coupled to the housing with the volume matrix and aperture plate secured therebetween, and an acoustically transparent filter held against the pressure plate. The pressure plate and the housing are configured to apply pressure to volume matrix and aperture plate sandwiched therebetween to create a tight seal, and the opening arrangements in combination with a corresponding chamber create a plurality of attenuators configured to match one or more dominant frequencies of one or more cooling fans within the cabinet such that the resonant frequency emanating from each attenuator have substantial phase inversion of the dominant frequencies, thereby cancelling noise emanating from the telecommunications cabinet.

Inventors

SMAILES, Richard

Assignees

Outdoor Wireless Networks LLC

Dates

Publication Date: 20260513
Application Date: 20251111

Claims (15)

An acoustic attenuation device adapted for use in a telecommunications cabinet, the device comprising: a housing comprising a cavity; a volume matrix sealed within the cavity of the housing, the volume matrix comprising a main body divided into a plurality of chambers; an aperture plate engaged with the volume matrix, the aperture plate comprising a plurality of opening arrangements, each opening arrangement aligned with a respective chamber of the volume matrix; a pressure plate coupled to the housing with the volume matrix and aperture plate secured therebetween, the pressure plate comprising a plurality of openings, each opening aligned with a respective opening arrangement in the aperture plate; and an acoustically transparent filter held against the pressure plate, wherein the pressure plate and the housing are configured to apply pressure to volume matrix and aperture plate sandwiched therebetween to create a tight seal, and wherein the opening arrangements of the aperture plate in combination with a corresponding chamber of the volume matrix create a plurality of attenuators configured to match one or more dominant frequencies of one or more cooling fans within the telecommunications cabinet such that the resonant frequency emanating from each attenuator have substantial phase inversion of the one or more dominant frequencies, thereby cancelling noise emanating from the telecommunications cabinet.
The acoustic attenuation device according to Claim 1, wherein at least one of the one or more cooling fans are part of a server, and wherein the device has compact size, thereby allowing the device to be fixed to an internal surface of the telecommunications cabinet in close proximity to server cooling fan while occupying minimal cabinet space.
The acoustic attenuation device according to any one of Claim 1 or Claim 2, further comprising an upper cap plate and a lower support plate, the upper cap plate and lower support plate configured to engage with the pressure plate to secure the filter in place.
The acoustic attenuation device according to any one of the preceding claims, wherein the housing further comprises four side walls extending outwardly from a backing plate, the backing plate and side walls together define the cavity configured to receive and hold the volume matrix therein.
The acoustic attenuation device according to any one of the preceding claims, wherein the plurality of chambers are arranged in a grid configuration in the main body of the volume matrix.
The acoustic attenuation device according to any one of the preceding claims, wherein the plurality of chambers are arranged in a series of rows and columns in the main body of the volume matrix.
The acoustic attenuation device according to any one of the preceding claims, wherein the volume matrix is formed from glass reinforced plastic and the aperture plate is formed from aluminum.
The acoustic attenuation device according to any one of the preceding claims, wherein the plurality of opening arrangements of the aperture plate have openings comprising a single oblong opening, two circular openings in a stacked arrangement, three circular openings in a triangular arrangement, and/or four circular openings in a square arrangement, and wherein in the plurality of opening arrangements together achieve a resonant frequency needed to match the dominant frequencies of the cooling fans within the telecommunications cabinet.
The acoustic attenuation device according to any one of the preceding claims, wherein the pressure plate further comprises an upper wall, a lower wall, and two opposing side walls extending outwardly from a main plate, the upper and lower walls extend outwardly from the main plate in a first direction and are configured to engage with the housing and the opposing side walls extend outwardly from the main plate in a second opposing direction and are configured to engage with and provide a mounting location for the filter.
The acoustic attenuation device according to any one of the preceding claims, wherein the pressure plate further comprises two flanged edges extending outwardly from the upper and lower walls, each flanged edge comprises a plurality of apertures configured to receive a respective fastener to secure the pressure plate to the housing, the fasteners are configured to pull the pressure plate and housing toward each other and apply pressure to the volume matrix and aperture plate sandwiched therebetween, thereby creating a tight seal.
The acoustic attenuation device according to any one of Claim 9 or Claim 10, wherein the opposing side walls further comprise a lip extending inwardly therefrom, and wherein the lip of each opposing side wall, the upper cap plate, and the lower support plate together are configured to hold and secure the filter against the pressure plate.
The acoustic attenuation device according to any one of Claims 3-11, wherein the upper cap plate comprises a main body having a flanged edge extending longitudinally and downwardly therefrom and arm members extending downwardly from opposing ends of the main body, each arm member is configured to secure the upper cap plate to the pressure plate and the flanged edge configured to hold and secure the filter against the pressure plate.
The acoustic attenuation device according to any one of Claims 3-12, wherein the lower support plate comprises a main body having a flanged edge extending longitudinally and upwardly therefrom and arm members extending upwardly from opposing ends of the main body, each arm member is configured to secure the lower support plate to the pressure plate and the flanged edge is configured to hold and secure the filter against the pressure plate.
The acoustic attenuation device according to any one of the preceding claims, wherein the filter comprises an open cell, acoustically transparent form.
The acoustic attenuation device according to any one of the preceding claims, wherein the filter is configured to act as an absorber to help increase the frequency bandwidth from each individual attenuator.

Description

Related Application(s) The present application claims priority to and the benefit of U.S. Provisional Patent Application Serial No. 63/719,176, filed November 12, 2024, the disclosures of which are hereby incorporated by reference as if set forth fully herein. Field The present invention is directed generally to telecommunications equipment, and more particularly, an acoustic attenuation device for use in telecommunications cabinets. Background Noise complaints about telecommunications cabinets placed close to residential areas are becoming more commonplace. Most of the noise coming from the telecommunications cabinets is generated by the cooling fans on the cabinet and/or the equipment (e.g., servers) housed within the main compartment of the cabinet. Air movement through the cabinet and ventilation openings (e.g., from cooling fans) generate white noise. The walls of the cabinet act as a resonating chamber which amplifies critical frequencies. The noise generated by the equipment and cabinet cooling fan blades has a frequency profile that emits a specific narrow band fundamental frequency with fifth and octave harmonics. The frequency spikes of the frequency profile for the cooling fans reside within the 1kHz to 4kHz range, which is the most sensitive frequency range of human hearing, and thus, the noise coming from the telecommunications cabinet is perceived as being louder and more disturbing. Typically, telecommunications cabinets use a negative pressure arrangement in which air is drawn in through louvres coupled with a filter in the cabinet door and the cabinet cooling fan(s) is housed in a void area in the roof of the cabinet and exhausted through a labyrinth of vents at the front and rear of roof. Current attempts to solve noise issues surrounding telecommunications cabinets include the application of noise deadening foam on the inner walls of the main compartment. Alternative ways to mitigate noise the heard from a telecommunications cabinet may be desired. Summary A first aspect of the present invention is directed to an acoustic attenuation device adapted for use in a telecommunications cabinet. The acoustic attenuation device includes a housing having a cavity and a volume matrix sealed within the cavity of the housing. The volume matrix has a main body divided into a plurality of chambers. The device further includes an aperture plate engaged with the volume matrix. The aperture plate has a plurality of opening arrangements, each opening arrangement aligned with a respective chamber of the volume matrix. The device further includes pressure plate coupled to the housing with the volume matrix and aperture plate secured therebetween. The pressure plate has a plurality of openings, each opening aligned with a respective opening arrangement in the aperture plate. The device also includes an acoustically transparent filter held against the pressure plate. The pressure plate and the housing are configured to apply pressure to volume matrix and aperture plate sandwiched therebetween to create a tight seal. The opening arrangements of the aperture plate, in combination with a corresponding chamber of the volume matrix, create a plurality of attenuators configured to match one or more dominant frequencies of one or more cooling fans within the telecommunications cabinet such that the resonant frequency emanating from each attenuator have substantial phase inversion of the one or more dominant frequencies, thereby cancelling noise emanating from the telecommunications cabinet. In some embodiments, at least one of the one or more cooling fans are part of a server, and the device has compact size, thereby allowing the device to be fixed to an internal surface of the telecommunications cabinet in close proximity to server cooling fan while occupying minimal cabinet space. In some embodiments, the acoustic attenuation device further includes an upper cap plate and a lower support plate, the upper cap plate and lower support plate are configured to engage with the pressure plate to secure the filter in place. In some embodiments, the housing further includes four side walls extending outwardly from a backing plate, the backing plate and side walls together define the cavity configured to receive and hold the volume matrix therein. In some embodiments, the housing further includes two flanged edges extending outwardly from opposing side walls, each flanged edge includes a plurality of apertures configured to receive a respective fastener to secure the pressure plate thereto and/or to mount and secure the acoustic attenuation device to an interior surface of the telecommunications cabinet. In some embodiments, the plurality of chambers are arranged in a grid configuration in the main body of the volume matrix. In some embodiments, the plurality of chambers are arranged in a series of rows and columns in the main body of the volume matrix. In some embodiments, the volume matrix is formed from glass reinforced p