Patent Publication Number: US-9850657-B2

Title: Acoustic panel for partition wall assembly

Description:
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. 
     These and other features, advantages, and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of a partition according to one aspect of the present disclosure; 
         FIG. 2  is an exploded isometric view of a partition having a plurality of acoustic panels; 
         FIG. 3  is an isometric view of an acoustic panel; 
         FIG. 4  is a partially fragmentary cross sectional view of a portion of the acoustic panel of  FIG. 3 ; 
         FIG. 5  is a cross sectional view of a portion of the partition of  FIG. 1 ; 
         FIG. 6  is fragmentary isometric view of a portion of a partition according to another aspect of the present disclosure; 
         FIG. 7  is a fragmentary cross sectional view of the partition of  FIG. 6 ; 
         FIG. 8  is a fragmentary, enlarged cross sectional view of the partition of  FIG. 7 ; and 
         FIG. 9  is a graph showing sound absorption coefficient versus frequency. 
     
    
    
     DETAILED DESCRIPTION 
     For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the components as oriented in  FIG. 1 . However, it is to be understood that the components may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
     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 to  FIG. 1 , a partition  1  includes first (front) and second (rear) opposite sides  2  and  3 , respectively and a partition frame  5 . One or more acoustic glass panels  4  (designated  4 A,  4 B,  4 C, and  4 D  FIG. 1 ) may be positioned between adjacent panels  6 A and  6 B. The adjacent panels  6 A and  6 B may comprise acoustic glass panels  4  that are substantially identical to the acoustic glass panel  4 . Alternatively, panels  6 A and  6 B 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 panel  4  may comprise a plurality of individual acoustic glass panels  4 A- 4 D that are vertically juxtaposed or stacked on top of one another and supported by a rigid partition frame  5 . Acoustic panels  4 A- 4 D may have substantially identical dimensions and construction. 
     With reference to  FIG. 2 , the partition frame  5  may comprise upright frame members  8 A and  8 B that, when assembled, are rigidly interconnected to horizontal frame members  10 B. Upright frame members  8 A and  8 B may have substantially the same cross sectional shape and configuration as horizontal frame members  10 A and  10 B. The partition frame members may include rows of slots  12  that are configured to receive hang-on accessory units, hooked brackets or the like. As discussed in more detail below, each panel  4  includes a front sheet  18  and upper openings  32  and lower openings  34  that are connected to interior chambers  38  of each panel  4  to define Helmholtz resonators that absorb noise. Thus, two spaced apart openings ( 32  and  34 ) are fluidly connected to a single interior chamber  38 . It will be understood that openings  32  and  34  could extend vertically along the vertical side edges of sheet  18  instead of horizontally along the upper and lower edges. Furthermore, openings could extend along both vertical and horizontal edges of sheet  18  to fluidly connect interior chamber  18  to air outside panel  4 . When assembled, strips  70  and  72  of fiberglass or other porous material extend over openings  32  and  34 . The frame members  8 A,  8 B,  10 A, and  10 B may be rigidly interconnected utilizing connectors (not shown) as described in more detail in U.S. Pat. No. 8,966,842. The partition  1  may 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 partition  1  and account for uneven floor surfaces. It will be understood that partition frame  5  may 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 to  FIG. 3 , an acoustic panel  4  includes vertical side panel frame members  14 A and  14 B that are rigidly connected to horizontal upper and lower panel frame members  16 A and  16 B, respectively, utilizing welds, threaded fasteners, or other suitable connecting structures/processes to form a generally rectangular panel frame  25  having an enlarged central opening  26 . A front sheet of material  18  is secured to a front side  22  of panel frame  25 , and a rear sheet  20  is secured to rear side  24  of panel frame  25  to thereby cover a substantial portion of the opening  26 . The front and rear sheets  18  and  20  preferably comprise transparent glass or polymer. However, the front and rear sheets  18  and  20  may comprise tined or translucent glass, polymers, or the like. Sheets  18  and  20  could, alternatively, comprise opaque solid, impermeable materials having low noise absorption characteristics (e.g. wood, metal, etc.). Alternatively, sheets  18  and/or  20  could comprise porous, sound-absorbing material if additional noise absorption is required. Upper edge  28  of front sheet  18  is spaced downwardly from a horizontal web or wall  36  of upper panel frame member  16 A to form openings  32 , and lower edge  30  of front sheet  18  is spaced upwardly from horizontal wall or web  36 B of lower horizontal frame member  16 B to form a lower opening  34 . The vertical side panel frame members  14 A and  14 B, horizontal panel frame members  16 A and  16 B, and front and rear sheets  18  and  20  together define the interior chambers  38 . The upper and lower openings  32  and  34  are fluidly connected to the interior chamber  38  and 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 with  FIG. 9 . It will be understood that the acoustic panel  4  may be configured to absorb sound in other frequency ranges as required. 
     The upright side panel frame members  14 A and  14 B include flanges  40  that are configured to secure the acoustic glass panels  4  to the partition frame  5 . The flanges  40  include outwardly-extending first portions  42 , and transverse end portions  44 . The vertical side edges  46  of first sheet  18  overlap the outwardly extending portions  42  of flanges  40 . The peripheral edge portion  48  of rear sheet  20  overlaps the frame members  16 A,  16 B,  18 A, and  18 B and thereby substantially closes off the rear side  24  of panel frame  25 . Thus, unlike front side  22  of panel  4 , rear side  24  of panel  4  does not include openings  32  or  34 . Thus, the rear side of panel  4  typically has a significantly higher noise absorption coefficient than front side  24 . 
     With further reference to  FIG. 4 , the upper and lower horizontal panel frame members  16 A and  16 B have substantially the same construction and cross-sectional configuration. In  FIG. 4 , the orientation of the front and rear sides  22  and  24  of the horizontal panel frame members  16 A and  16 B is opposite the orientation of  FIG. 3  to more clearly show the rows of individual slots/openings  52  forming upper and lower openings  32  and  34 . The horizontal panel frame members  16 A and  16 B include a horizontal central wall or web  36 . Front side  22  includes an upwardly extending flange  54  that is folded downwardly along fold line  56  to form a downwardly extending flange portion  58 . Outwardly and upwardly extending flange portions  60  and  62 , respectively, together with downwardly extending portion  58  define a channel  64  that receives an upper or lower edge  28  or  30  of front sheet  18  ( FIG. 3 ). A plurality of elongated slots or openings  52  are formed in the flange  54  and a portion of horizontal wall  36 . A plurality of reinforcements  66  extend between horizontal wall  36  and flange  54 . A plurality of individual openings  52  thereby form the horizontally elongated upper and lower openings  32  and  34 , respectively. Rear side  22  of frame members  16  include flanges  54 A,  58 A,  60 A, and  62 A forming channel  64 A that receives an upper or lower edge of rear sheet  20  when assembled. In contrast, to flange  54 , flange  54 A does not include openings  52 , such that interior chamber  38  does not open to second or rear side  24  of panel  14 . 
     With further reference to  FIG. 5 , when assembled the vertically adjacent acoustic glass panels  4 A- 4 B etc. are stacked on top of each other with horizontal walls  36 A of lower frame members  16 B disposed on walls  36 B of upper frame members  16 A. Vertically adjacent acoustic panels  4  may be interconnected utilizing threaded fasteners or other suitable connectors. Alternatively, adjacent acoustic panels  4  may be retained in an assembled/stacked configuration by gravity. When assembled, rear edges  41  ( FIG. 3 ) of flanges  40  abut front faces  9 A and  9 B ( FIG. 2 ) of upright partition frame members  8 A and  8 B, respectively. The panel frames  25  may be secured to the partition frame members  8 A,  8 B,  10 A, and  10 B utilizing threaded fasteners (not shown) or other suitable connectors. 
     Referring again to  FIG. 5 , the adjacent upper and lower openings  32  and  34  formed by the individual openings  52  are fluidly connected to a gap or opening  68  having a dimension “G” formed between the flanges  60  of adjacent panels  4 . A strip  70  is disposed in the opening  68 . Strip  70  comprises fiberglass or other suitable porous material that increases the flow resistance of air passing through the openings into chambers  38  to thereby absorb sound. Strips  72  of porous material may be disposed in an uppermost opening  32  along an upper edge of upper acoustic glass panel  4 A, and a strip  72  may be disposed in a lowermost opening  34  of the lowermost acoustic glass panel  4 C. The strips  72  have substantially the same construction (e.g. same material) as strip  70 , but have a reduced height to fit into smaller gaps G 1  and G 2  formed by openings  32  and  34  along the upper and lower edges of acoustic glass panels  4 A and  4 B. Strips  70  and  72  allow sound to pass through openings  32  and  34 . However, the porous strips  70  and  72  dissipate the energy of the sound waves as the air passes through openings  32  and  34 , thereby increasing the noise reduction coefficient. Testing of panels  4  constructed 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 material  70  and  72  are disposed across openings  32  and  34 , relative to the noise reduction coefficient (e.g. approximately 0.2 average for 125-500 Hz frequencies) if strips  70  and  72  are not present. In  FIG. 5 , the lowermost acoustic glass panel is designated “ 4 B.” However, it will be understood that the number of acoustic glass panels  4  will vary as required to provide the desired height for a particular application. 
     The volume of the interior chambers  38 A and  38 B and the size of the openings  32  and  34  are selected to form a Helmholtz resonator. The volume of the interior chambers  38  and the openings  32  and  34  may be selected to provide an increased sound absorption coefficient in a particular frequency range as required for a particular application. In one embodiment, the chambers  38  have a volume of about 1,500-3,000 cubic inches, and the upper and lower openings  51  have a total combined cross sectional area of about 40-50 square inches. Also, the upper and lower edges  28  and  30  ( FIG. 3 ) of sheets  18  and  20  may be about 30-60 inches, and the sheets  18  and  20  may be about 12-36 inches high. the 125-500 Hz frequency range as shown in  FIG. 9 . A relatively high percentage of human speech is in the 125-500 Hz range, and the acoustic glass panels  4  are 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 panels  4  of partition  1  significantly reduce the noise in office settings and the like. 
     Acoustic panel  4  is configured to provide an average noise reduction coefficient (“NRC”) of about 0.45 for 125-500 Hz as shown in  FIG. 9 . 0.45 is the average absorption coefficient @250, 500, 1000, &amp; 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 panel  4  may be adjusted by varying the volume of interior chamber  38  and/or openings  32  and/or  34 , and/or by adjusting the composition and/or configuration of the filler strips  70  and  72 . 
     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 )))}
 
     where: 
     According to one example, if r=0.75 inches, o=3.649 inches, w=16.48 inches, and d=0.292 inches 
     
       
         
           
             
               
                 
                   f 
                   = 
                     
                   ⁢ 
                   
                     2160 
                     × 
                     
                       ( 
                       
                         .75 
                         / 
                         
                           
                             ( 
                             
                               
                                 ( 
                                 
                                   .292 
                                   * 
                                   1.2 
                                   * 
                                   3.649 
                                 
                                 ) 
                               
                               * 
                               
                                 ( 
                                 
                                   .75 
                                   * 
                                   16.48 
                                 
                                 ) 
                               
                             
                             ) 
                           
                           .5 
                         
                       
                     
                   
                 
               
             
             
               
                 
                   = 
                     
                   ⁢ 
                   
                     449 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     Hz 
                   
                 
               
             
           
         
       
     
     This may be adjusted for insulation, if insulation (e.g. strips  70 ) is present 
     
       
         
           
             
               
                 
                   f 
                   = 
                     
                   ⁢ 
                   
                     449 
                     * 
                     
                       1 
                       
                         √ 
                         2 
                       
                     
                   
                 
               
             
             
               
                 
                   = 
                     
                   ⁢ 
                   
                     318 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     Hz 
                   
                 
               
             
           
         
       
     
     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 to  FIGS. 6-8 , an acoustic panel  85  according to another aspect of the present disclosure includes a plurality of vertically juxtaposed first or front sheets of glass  18 A, and a single second or rear sheet of glass  20 A. A plurality of dividers or partitions  76  extend between and interconnect the sheets  18 A and  20 A to define interior chambers  38 A. The dividers  76  include a rear portion  78  that is attached or sealed to inner surface  86  of sheet  20 A. Dividers  76  also include a front portion  80  having upwardly and downwardly opening channels  82  and  84 , respectively, that receive horizontal edge portions  88  of front sheets  18 A. The front portion  80  of divider  76  includes a front channel or opening  68 A between the adjacent sheets  18 A. A strip  70  of porous material such as fiberglass is disposed in the opening or channel  68 A. The opening or channel  68 A is fluidly connected to openings  32 A and  34 A such that the interior chambers  38 A are fluidly connected to the space exterior of the panel  85  to form Helmholtz resonators in substantially the same manner as described above in connection with the acoustic panels of  FIGS. 1-5 . 
     The upper acoustic glass panel  4 A includes an interior chamber  38 A, and the glass panel  4 B has an interior chamber  38 B. The interior chambers  38 A and  38 B are fluidly connected through openings  32  and  34  and a single gap or opening  68  disposed adjacent intersection or joint  74  between acoustic panels  4 A and  4 B. 
     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, openings  32  and  34  could extend along the vertical side edges of sheet  18  rather than the upper and lower edges of sheet  18 . Alternatively openings to interior chamber  38  could be provided along substantially the entire perimeter of sheet  18 , or only along selected portions thereof.