Abstract:
Noise dampers of sound absorbent material are inserted on the metal grid beams in a suspended ceiling. 
     Hangers, embedded in a structural ceiling, that support the beams, are insulated from the beams by the noise dampers. 
     Sound vibrations generated in the structural ceiling, which is often a floor, are not transmitted through the hangers, to the suspended ceiling, or to the room, below, but are absorbed in the dampers before reaching the grid beams.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to noise control in suspended ceilings. Such suspended ceilings have a grid of intersecting metal beams that are suspended by hangers from a structural ceiling. Panels or drywall sheets are supported on the grid. 
         [0003]    Noise generated in the structural ceiling, which is frequently a floor for the space above, is transmitted by sound vibrations passing downward through the hangers, which form a sound path, to the grid of the suspended ceiling. The suspended ceiling, which includes panels or drywall sheets attached to the beams in the grid, forms a receiver for the sound vibrations, which broadcasts the resulting unwanted noise to the space below. 
         [0004]    The invention deals with deadening such sound vibrations coming down the hangers. 
         [0005]    2. Prior Art 
         [0006]    Suspended ceilings are constructed in a special way so that the ceilings are extremely stable. Over many years, a standard way of constructing such ceilings has evolved. Suspended ceilings are constructed at a building site by individually explosively embedding an anchor such as an eye bolt, into the structural ceiling, and then attaching a hanger, such as a wire, to the anchor, by twisting the wire about the anchor. The lower end of the hanger is attached to a metal beam in a grid that supports panels, or drywall sheets, by looping the hanger through a hole in the web of the beam and twisting the loop closed around the bulb and a segment of the beam. 
         [0007]    The substantial weight of the suspended ceiling is spread among numerous hangers that are spaced every few feet along the main beams in the grid. Each hanger must be individually secured to the structural ceiling, and to the grid beam, by an installer who must keep the grid of interconnected main and cross beams level at a desired height. Much time and effort is required to hang a suspended ceiling grid from a structural ceiling. 
         [0008]    Much more time and effort is required where sound attenuator devices that dampen the vibrations coming down a hanger sound path, from noise generated in a structural ceiling, are used. 
         [0009]    In the prior art, to control noise in a suspended ceiling, a noise attenuator is individually inserted by the installer, about midway in the length of a wire hanger that is cut into two segments. An upper segment of the wire hanger is first secured at its top to the structural ceiling, and at its bottom, to a top terminal in the attenuator. A lower segment of the wire hanger is connected at the top to a bottom terminal in the attenuator, and then, at the bottom of the lower segment, to the grid beam. 
         [0010]    In such prior art attenuator, the upper and lower metal terminals are separated from each other by a suitable amount of sound vibration damping material, such as gum rubber. Sound vibrations coming down the wire hanger sound path from the structural ceiling, which frequently serves as a floor for the building level above, are absorbed in the noise attenuator. 
         [0011]    The insertion of such prior art noise attenuators in a wire hanger that must be divided into two segments is time and labor consuming, since the normally single segment of a wire hanger must not only be divided into two segments, but each segment must then be secured to the noise attenuator by passing the hanger through an attenuator terminal, and then twisting the hanger back around the segment. Thus, instead of just two attachments of a single segment of a wire hanger at an upper end to the structural ceiling, and at its lower end to a grid beam itself, as in prior art suspended ceilings with no noise attenuation, there are two additional attachments involving threading the wire hanger through a hole, and then twisting the wire hanger back upon itself, to the noise attenuator. 
         [0012]    Such manual cutting, threading, and twisting must be individually custom performed by the installer of the grid in the field during the construction of the ceiling, since good judgment must be exerted at each wire hanger to keep the grid level, through controlling the length of the wire hanger suspensions. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    A noise damper, of material that deadens sound vibrations coming down a hanger, is inserted between the grid beam and a hanger in the construction of the suspended ceiling. 
         [0014]    The noise damper insulates the entire hanger attached to the structural ceiling from contact with the metal grid beam in the suspended ceiling, so the sound vibrations passing down the hanger are deadened in the noise damper. The noise damper, however, does not interfere with the structural support of the grid beam and suspended ceiling by the hangers, which are generally of wire, but permissibly of other material having adequate tensile strength to support the suspended ceiling. 
         [0015]    The time required to install a suspended ceiling with the present invention is virtually the same as the time required to install a prior art suspended ceiling without any noise damping. In the present invention, the noise damper, which is of a resilient, sound vibration deadening material, can be merely inserted into place, and the hanger attached to the beam by looping a wire hanger through a knock-out in the beam, as done in the prior art in a suspended ceiling that is not sound dampened. 
         [0016]    The knock-out can be shaped so the stress that the suspended ceiling imparts to the hanger where it passes through the knock-out is distributed over a section of the noise damper, rather than concentrated at the site of the hanger. 
     
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWING 
         [0017]      FIG. 1  is a perspective view of the noise damper of the invention. 
           [0018]      FIG. 2  is an elevational view comparing
       (a) a prior art suspended ceiling segment without noise damping;   (b) a prior art ceiling segment with noise damping; and   (c) a suspended ceiling with the noise damper of the invention       
 
           [0022]      FIG. 3  is a side elevational view of a noise damper in place on a grid beam with a wire hanger looped through the noise damper and beam. 
           [0023]      FIG. 4  is an exploded perspective view of a section of a grid beam showing a knock-out that seats a conforming raised section of a noise damper. 
           [0024]      FIG. 5  is an enlarged sectional view taken on the line  5 - 5  in  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    Although the invention is illustrated with hangers of wires, which is the predominant material used to suspend present day ceilings, the invention can be used with other forms of hangers, such as rods, or chains. 
         [0026]    In  FIG. 2 , there is shown comparatively (a) a prior art ceiling without noise damping; (b) a prior art ceiling with noise damping; and (c) the noise dampened suspended ceiling of the present invention. In a prior art suspended ceiling installation without noise damping, ( FIG. 2   a ), the suspended ceiling  43 , is hung from a structural ceiling  22 , by wire hangers  40  embedded in the structural ceiling at the top, and looped through about the grid beam  21  at the bottom. A single length of wire hanger  40  is used. 
         [0027]    In  FIG. 2   b , a wire hanger is cut in two into segments,  23  and  24 , and secured to the structural ceiling  22  and suspended ceiling  43  as shown. A grid beam  21  is suspended from structural ceiling  22  by an upper wire segment  23  and a lower wire segment  24 , connected to a sound attenuator  25 . The upper wire segment  23  is looped through an eye bolt  26  explosively embedded in the structural ceiling  22 , and manually twisted to close the loop  27 . Similar connections are made to sound attenuator  25  at the bottom of segment  23  and at the top of the lower segment  24 . At the bottom of the lower segment  24 , there is formed a loop  27  that passes through a hole  28  in the web  29  of grid beam  21 . The loop  27  is closed by twisting the wire hanger segment  24 . 
         [0028]    In the present invention, as shown in  FIG. 2   c , a single length of wire hanger  40  is used to suspend a beam  21  at suspension points along the beam  21 . A noise damper is inserted onto grid beam  21  between the suspension loop  42  at the bottom of wire hanger  40  and the grid beam  21 , to insulate the beam  21  from the wire hanger  40 . The noise damper  41  of the invention deadens the sound vibrations from structural ceiling  22  as they travel down the wire hanger  40 , before the vibrations reach the metal grid beam  21 , in the suspended ceiling  43 , which would serve as a receiver that would broadcast the noise to the space below. 
         [0029]    At the top, the wire hanger  40  is looped through eye bolt  26  explosively embedded in structural ceiling  22 , and the loop  44  is twisted closed. The lower end of wire hanger is passed through hole  61  in noise damper  41  on grid beam  21 , and passes through knock-out  46 . 
         [0030]    Noise damper  41  has an inverted U-shaped upper portion  47  conforming in cross section to the bulb  48  of the grid beam  21 , as seen particularly in  FIG. 5 . A flat lower portion  51  is intended to lie along the web  29  of the grid beam  21  as seen in  FIG. 5 . 
         [0031]    A raised insert  53  on flat lower portion  51  is shaped to conform to a knock-out  46 , desirably with the shape of an arch  56  at the top. Lip retainers  57  hold the raised insert  53  firmly in the knock-out  46 . An angled lip  58  on the U-shape clip portion  47  retains such U-shaped portion  47  of the noise damper  41  on the bulb  48  of the grid beam  21 . A hole  61  that receives wire hanger  40  extends through the raised insert  53  and knock-out  46 . 
         [0032]    The noise damper  41  is injection molded into one resilient integral piece from a vibration deadening material. An example of such a material is thermoplastic vulcanizate, an elastomer, that includes carbon black and a paraffin wax. Such material, in pellet form, is injection molded into the form of the noise damper  41  insert of the invention. The noise damper  41 , when molded, is flexible, and can readily expand when being inserted onto the grid beam  21 , to envelope the grid beam  21  as depicted in the drawings. 
         [0033]    The noise damper  41  is inserted onto the beam by passing the inverted U-shape portion  47  vertically downward over the bulb  48  of grid beam  21  to seat raised insert  53  in knock-out  46 . The noise damper  41  expands while being inserted onto the grid beam  21 , and contracts to the position about the beam  21 , and into knockout  46 , as shown particularly in  FIGS. 3 and 5 . 
         [0034]    A single length of wire hanger  40 , which has been embedded previously in the structured ceiling, is then looped through the hole  61  in the noise damper  41 , as shown in  FIG. 5 , and then twisted at  62  to close the loop. 
         [0035]    In this manner, the metal wire hanger  40  is insulated from metal grid beam  21 , while still structurally supporting the grid beam  21 . 
         [0036]    A series of wire hangers  40  and noise dampers  41  are applied at, for instance, four (4) foot intervals along the main grid beams  21 . The knock-outs  46  may be pre-punched at more frequent intervals, along the beam, and the noise dampers inserted selectively. The knock-outs  46  do not appreciatively affect the strength of the grid beams  21 . 
         [0037]    By means of the present invention, as set forth above, the hanger  40  which acts as a sound path from the structural ceiling  22  noise source to the suspended ceiling  43  which acts as a receiver is interrupted and dampened by the noise damper  41  of the invention. 
         [0038]    The noise dampers  41  can be inserted at the job site as the grid beams  21  are being hung, or in the alternative, the noise dampers  41  can be inserted on the grid beams  21  before the grid beams  21  themselves are shipped to the job site. 
         [0039]    In case of a fire, even though the noise dampers  41  of the invention are destroyed, wire hangers  40  continue to support the grid beams  21 , since the wire hangers  40  remain attached to the grid beams  21 .