Acoustic panel for partition wall assembly

An office partition system including a partition frame having front and rear sides. Front and rear transparent sheet material is disposed on the front and rear sides of the partition frame, respectively. Horizontally and vertically extending dividers are disposed between the front and rear transparent sheet material to define a plurality of vertically juxtaposed interior chambers. The front transparent sheet material comprises a plurality of first sheets, each first sheet having horizontally-extending upper and lower edges. The upper and lower edges of adjacent first sheets are vertically spaced apart to define horizontally elongated gaps therebetween. The horizontally elongated gaps are fluidly connected to interior chambers disposed above and below the horizontal dividers to define Helmholtz resonators whereby sound that is incident on the front side of the partition frame is absorbed to the Helmholtz resonance.

BACKGROUND OF THE INVENTION

Various types of office partition systems have been developed. In order to reduce noise levels, known office partitions may include sound-absorbing panels comprising cloth, porous backing material, and other such materials that are configured to absorb sound. Office partitions/walls may include glass or other transparent panels that permit users to see through the partition/wall. However, known glass panels typically reflect a relatively high percentage of the sound incident on the glass partition.

SUMMARY OF THE INVENTION

One aspect of the present disclosure is an acoustic panel assembly having first and second opposite sides. The acoustic panel assembly may be configured for use as an office partition. The acoustic panel assembly includes a generally quadrilateral panel frame having first and second opposite sides. The panel frame includes vertical side frame members and upper and lower horizontal frame members extending between and interconnecting the vertical side frame members. A central opening extends through the panel frame. The acoustic panel assembly also includes first and second sheets of glass or other suitable light-transmitting impermeable solid material disposed on the first and second opposite sides of the panel frame, respectively, and extending over the central opening. An interior chamber is defined by the first and second sheets, the vertical side frame members, and the upper and lower horizontal frame members. The first sheet defines upper and lower edges, wherein the upper edge is spaced apart from a portion of the upper horizontal frame member to define an upper opening. The lower edge is spaced apart from a portion of the lower horizontal frame member to define a lower opening. Porous material may be disposed in the upper and lower openings. The upper and lower openings connect to the interior chamber to form a Helmholtz resonator such that the first side of the acoustic panel assembly has an average noise reduction coefficient of at least about 0.6 for 125 to 500 Hz.

Another aspect of the present disclosure is an office partition system including a partition frame. The partition frame includes at least two upright partition frame members and at least two horizontally-extending partition frame members that are rigidly interconnected to the upright partition frame members. The office partition system also includes upper and lower vertically juxtaposed acoustic panels disposed between the upright partition frame members. Each acoustic panel includes a generally quadrilateral panel frame and first and second sheets of light-transmitting impermeable solid material. The panel frame includes vertical side panel frame members and upper and lower horizontal panel frame members extending between and interconnecting the vertical side panel frame members such that the panel frame defines a central opening through the panel frame. The first and second sheets are disposed on the opposite sides of the panel frame, and extend over the central opening to define an interior chamber between the first and second sheets, the vertical side panel frame members, and the upper and lower horizontal frame members. The first sheet defines upper and lower edges. The lower edge of the first sheet of the upper acoustic panel is vertically spaced from the upper edge of the first sheet of the lower acoustic panel to define an elongated horizontal opening that is fluidly connected to the interior chambers of the upper and lower acoustic panels to form a Helmholtz resonator that provides maximum absorption for frequency corresponding to adult human speech. Maximum absorption is preferably between about 125 and about 500 Hz.

Another aspect of the present disclosure is an office partition system including a partition frame having front and rear sides. Front and rear transparent sheet material is disposed on the front and rear sides of the partition frame, respectively. Horizontally and vertically extending dividers are disposed between the front and rear transparent sheet material to define a plurality of vertically juxtaposed interior chambers. The front transparent sheet material comprises a plurality of first sheets, each first sheet having horizontally-extending upper and lower edges. The upper and lower edges of adjacent first sheets are vertically spaced apart to define horizontally elongated gaps therebetween. The horizontally elongated gaps are fluidly connected to interior chambers disposed above and below the horizontal dividers to define Helmholtz resonators whereby sound that is incident on the front side of the partition frame is absorbed due to the Helmholtz resonance.

DETAILED DESCRIPTION

This patent application is related to U.S. Pat. No. 8,966,842, issued on Mar. 3, 2015, entitled “FLOOR-TO-CEILING PARTITION WALL ASSEMBLY,” the entire contents of which are incorporated herein by reference.

With reference toFIG. 1, a partition1includes first (front) and second (rear) opposite sides2and3, respectively and a partition frame5. One or more acoustic glass panels4(designated4A,4B,4C, and4DFIG. 1) may be positioned between adjacent panels6A and6B. The adjacent panels6A and6B may comprise acoustic glass panels4that are substantially identical to the acoustic glass panel4. Alternatively, panels6A and6B may comprise conventional partitions having panels including fabric, wood, or other conventional materials as described in more detail in above-identified U.S. Pat. No. 8,966,842. The acoustic glass panel4may comprise a plurality of individual acoustic glass panels4A-4D that are vertically juxtaposed or stacked on top of one another and supported by a rigid partition frame5. Acoustic panels4A-4D may have substantially identical dimensions and construction.

With reference toFIG. 2, the partition frame5may comprise upright frame members8A and8B that, when assembled, are rigidly interconnected to horizontal frame members10B. Upright frame members8A and8B may have substantially the same cross sectional shape and configuration as horizontal frame members10A and10B. The partition frame members may include rows of slots12that are configured to receive hang-on accessory units, hooked brackets or the like. As discussed in more detail below, each panel4includes a front sheet18and upper openings32and lower openings34that are connected to interior chambers38of each panel4to define Helmholtz resonators that absorb noise. Thus, two spaced apart openings (32and34) are fluidly connected to a single interior chamber38. It will be understood that openings32and34could extend vertically along the vertical side edges of sheet18instead of horizontally along the upper and lower edges. Furthermore, openings could extend along both vertical and horizontal edges of sheet18to fluidly connect interior chamber18to air outside panel4. When assembled, strips70and72of fiberglass or other porous material extend over openings32and34. The frame members8A,8B,10A, and10B may be rigidly interconnected utilizing connectors (not shown) as described in more detail in U.S. Pat. No. 8,966,842. The partition1may also include a floor rail and a threaded height adjustment assembly (not shown) as described in U.S. Pat. No. 8,966,842 to thereby adjust the height of the partition1and account for uneven floor surfaces. It will be understood that partition frame5may comprise other frames, and the present disclosure is not limited to the specific arrangements described herein and in U.S. Pat. No. 8,966,842.

With further reference toFIG. 3, an acoustic panel4includes vertical side panel frame members14A and14B that are rigidly connected to horizontal upper and lower panel frame members16A and16B, respectively, utilizing welds, threaded fasteners, or other suitable connecting structures/processes to form a generally rectangular panel frame25having an enlarged central opening26. A front sheet of material18is secured to a front side22of panel frame25, and a rear sheet20is secured to rear side24of panel frame25to thereby cover a substantial portion of the opening26. The front and rear sheets18and20preferably comprise transparent glass or polymer. However, the front and rear sheets18and20may comprise tined or translucent glass, polymers, or the like. Sheets18and20could, alternatively, comprise opaque solid, impermeable materials having low noise absorption characteristics (e.g. wood, metal, etc.). Alternatively, sheets18and/or20could comprise porous, sound-absorbing material if additional noise absorption is required. Upper edge28of front sheet18is spaced downwardly from a horizontal web or wall36of upper panel frame member16A to form openings32, and lower edge30of front sheet18is spaced upwardly from horizontal wall or web36B of lower horizontal frame member16B to form a lower opening34. The vertical side panel frame members14A and14B, horizontal panel frame members16A and16B, and front and rear sheets18and20together define the interior chambers38. The upper and lower openings32and34are fluidly connected to the interior chamber38and form a Helmholtz resonator that is tuned for maximum absorption (e.g. has a sound absorption coefficient that is generally equal to or above 0.45) in frequencies corresponding to human speech. In a preferred embodiment, the sound absorption coefficient is equal to or above 0.5 in the 125-500 Hz range as discussed in more detail below in connection withFIG. 9. It will be understood that the acoustic panel4may be configured to absorb sound in other frequency ranges as required.

The upright side panel frame members14A and14B include flanges40that are configured to secure the acoustic glass panels4to the partition frame5. The flanges40include outwardly-extending first portions42, and transverse end portions44. The vertical side edges46of first sheet18overlap the outwardly extending portions42of flanges40. The peripheral edge portion48of rear sheet20overlaps the frame members16A,16B,18A, and18B and thereby substantially closes off the rear side24of panel frame25. Thus, unlike front side22of panel4, rear side24of panel4does not include openings32or34. Thus, the rear side of panel4typically has a significantly higher noise absorption coefficient than front side24.

With further reference toFIG. 4, the upper and lower horizontal panel frame members16A and16B have substantially the same construction and cross-sectional configuration. InFIG. 4, the orientation of the front and rear sides22and24of the horizontal panel frame members16A and16B is opposite the orientation ofFIG. 3to more clearly show the rows of individual slots/openings52forming upper and lower openings32and34. The horizontal panel frame members16A and16B include a horizontal central wall or web36. Front side22includes an upwardly extending flange54that is folded downwardly along fold line56to form a downwardly extending flange portion58. Outwardly and upwardly extending flange portions60and62, respectively, together with downwardly extending portion58define a channel64that receives an upper or lower edge28or30of front sheet18(FIG. 3). A plurality of elongated slots or openings52are formed in the flange54and a portion of horizontal wall36. A plurality of reinforcements66extend between horizontal wall36and flange54. A plurality of individual openings52thereby form the horizontally elongated upper and lower openings32and34, respectively. Rear side22of frame members16include flanges54A,58A,60A, and62A forming channel64A that receives an upper or lower edge of rear sheet20when assembled. In contrast, to flange54, flange54A does not include openings52, such that interior chamber38does not open to second or rear side24of panel14.

With further reference toFIG. 5, when assembled the vertically adjacent acoustic glass panels4A-4B etc. are stacked on top of each other with horizontal walls36A of lower frame members16B disposed on walls36B of upper frame members16A. Vertically adjacent acoustic panels4may be interconnected utilizing threaded fasteners or other suitable connectors. Alternatively, adjacent acoustic panels4may be retained in an assembled/stacked configuration by gravity. When assembled, rear edges41(FIG. 3) of flanges40abut front faces9A and9B (FIG. 2) of upright partition frame members8A and8B, respectively. The panel frames25may be secured to the partition frame members8A,8B,10A, and10B utilizing threaded fasteners (not shown) or other suitable connectors.

Referring again toFIG. 5, the adjacent upper and lower openings32and34formed by the individual openings52are fluidly connected to a gap or opening68having a dimension “G” formed between the flanges60of adjacent panels4. A strip70is disposed in the opening68. Strip70comprises fiberglass or other suitable porous material that increases the flow resistance of air passing through the openings into chambers38to thereby absorb sound. Strips72of porous material may be disposed in an uppermost opening32along an upper edge of upper acoustic glass panel4A, and a strip72may be disposed in a lowermost opening34of the lowermost acoustic glass panel4C. The strips72have substantially the same construction (e.g. same material) as strip70, but have a reduced height to fit into smaller gaps G1and G2formed by openings32and34along the upper and lower edges of acoustic glass panels4A and4B. Strips70and72allow sound to pass through openings32and34. However, the porous strips70and72dissipate the energy of the sound waves as the air passes through openings32and34, thereby increasing the noise reduction coefficient. Testing of panels4constructed as described herein showed that a significantly larger noise reduction coefficient (e.g. 0.6 to 0.65 average for 125-500 Hz frequencies) is obtained if porous strips of material70and72are disposed across openings32and34, relative to the noise reduction coefficient (e.g. approximately 0.2 average for 125-500 Hz frequencies) if strips70and72are not present. InFIG. 5, the lowermost acoustic glass panel is designated “4B.” However, it will be understood that the number of acoustic glass panels4will vary as required to provide the desired height for a particular application.

The volume of the interior chambers38A and38B and the size of the openings32and34are selected to form a Helmholtz resonator. The volume of the interior chambers38and the openings32and34may be selected to provide an increased sound absorption coefficient in a particular frequency range as required for a particular application. In one embodiment, the chambers38have a volume of about 1,500-3,000 cubic inches, and the upper and lower openings51have a total combined cross sectional area of about 40-50 square inches. Also, the upper and lower edges28and30(FIG. 3) of sheets18and20may be about 30-60 inches, and the sheets18and20may be about 12-36 inches high. the 125-500 Hz frequency range as shown inFIG. 9. A relatively high percentage of human speech is in the 125-500 Hz range, and the acoustic glass panels4are therefore preferably configured to absorb a high percentage of the sound in the 125-500 Hz range for use in offices or other similar environments in which noise in the 125-500 Hz range is produced. In this way, the acoustic glass panels4of partition1significantly reduce the noise in office settings and the like.

Acoustic panel4is configured to provide an average noise reduction coefficient (“NRC”) of about 0.45 for 125-500 Hz as shown inFIG. 9. 0.45 is the average absorption coefficient @250, 500, 1000, & 2000 Hz. The NRC that has been calculated as the average of 125, 160, 200, 250, 315, 400, and 500 Mz. It will be understood that the specific sound absorption characteristics of a particular acoustic glass panel4may be adjusted by varying the volume of interior chamber38and/or openings32and/or34, and/or by adjusting the composition and/or configuration of the filler strips70and72.

Various approaches can be utilized to estimate the Helmholtz frequency of the acoustic panels of the present disclosure. For example, a general equation for frequency determination that may be utilized to optimize the Helmholtz cavity is:
f=2160*√{square root over (r/((d*1.2*0*(r+w)))}

This may be adjusted for insulation, if insulation (e.g. strips70) is present

It will be understood that equation 1.0 provides an estimated Helmholtz frequency that may be useful in providing acoustic panels. However, the present invention is not limited to panels having a Helmholtz frequency that can be estimated utilizing the given equation. Various design methods and/or testing may be utilized to provide an acoustic panel having the sound absorption characteristics that may be required for a particular application. Also, the dimensions utilized in the example above merely show one possible design, and the present invention is not limited to this example. Nevertheless, it is noted that the estimated Helmholtz frequency (318 Hz) of the example is within the frequency range of 125-500 Hz for human speech, which may be utilized as a design criteria to provide acoustic panels that are suitable for use in office environments or the like. In general, an acoustic panel may be configured to have a Helmholtz frequency near the midpoint of the frequency range of interest (e.g. 312.5 Hz if the frequency range is 125-500 Hz) to provide the required acoustic characteristics (e.g. NRC) for the frequency range of interest.

With further reference toFIGS. 6-8, an acoustic panel85according to another aspect of the present disclosure includes a plurality of vertically juxtaposed first or front sheets of glass18A, and a single second or rear sheet of glass20A. A plurality of dividers or partitions76extend between and interconnect the sheets18A and20A to define interior chambers38A. The dividers76include a rear portion78that is attached or sealed to inner surface86of sheet20A. Dividers76also include a front portion80having upwardly and downwardly opening channels82and84, respectively, that receive horizontal edge portions88of front sheets18A. The front portion80of divider76includes a front channel or opening68A between the adjacent sheets18A. A strip70of porous material such as fiberglass is disposed in the opening or channel68A. The opening or channel68A is fluidly connected to openings32A and34A such that the interior chambers38A are fluidly connected to the space exterior of the panel85to form Helmholtz resonators in substantially the same manner as described above in connection with the acoustic panels ofFIGS. 1-5.

The upper acoustic glass panel4A includes an interior chamber38A, and the glass panel4B has an interior chamber38B. The interior chambers38A and38B are fluidly connected through openings32and34and a single gap or opening68disposed adjacent intersection or joint74between acoustic panels4A and4B.

It is to be understood that variations and modifications can be made on the aforementioned structure without departing from the concepts disclosed herein, and further it is to be understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise. For example, openings32and34could extend along the vertical side edges of sheet18rather than the upper and lower edges of sheet18. Alternatively openings to interior chamber38could be provided along substantially the entire perimeter of sheet18, or only along selected portions thereof.