Acoustical absorber

A readily removable and replaceable acoustical absorber for mounting in a channel that utilizes a flexible grid within the absorber to support the absorber on flanges of angles mounted on the channel walls.

BACKGROUND OF THE INVENTION 
This invention relates to acoustical absorbers and, more particularly, it 
relates to mounting the absorbers. 
In some environments it is important that acoustical absorbers be readily 
removable and replaceable for cleaning, repair, etc. It is also important 
that such absorbers fit properly, will not burn, are environmentally inert 
and also can be finished to match its surroundings. 
SUMMARY OF THE INVENTION 
The present invention provides such an absorber for mounting in an 
elongated structure having a generally U-shaped cross section which is 
defined by rigid side and back walls. A pair of angles are fixed at 
directly opposed locations on the side walls within the structure with 
their flanges facing each other. An elongated resilient acoustical 
absorber having the approximate size and shape of the generally U-shaped 
section has notches running the length of its side edges. Each notch has a 
surface formed to mate with the angle flanges which then support the 
absorber when it is installed in the U-shaped section. The absorber is 
installed by inserting or mating one of the notches with a flange and then 
compressing the opposite notched side edge while applying a force between 
the edges to position the opposite side notch to mate with the other one 
of the flanges and compress the absorber against the back wall of the 
U-shaped section whereby a returning force acts on said absorber to cause 
it to conform to said section. 
Preferably the absorber is formed from a flexible grid sandwiched between 
two open cell foam panels. The grid which provides support for the 
absorbers by resting on the flanges of the angles is preferably made from 
expanded metal. 
In another embodiment a sound absorbing fabric layer is located within one 
of the foam panels and, as a safety measure, both the foam and the fabric 
are fire-retardant. 
The foam may be selected from neoprene, urethane, polyimide foam or rubber. 
The fabric may be selected from woven, nonwoven, knit, synthetic or 
natural materials. 
The acoustical resistance of the absorber is preferably in the range of 
from 1 to 10 .rho.c units where 1 .rho.c unit equals 41.3 cgs rayl. The 
absorber thickness may range from 1 to 16 inches thick but most usually 
ranges from 2 to 8 inches in thickness. 
The mounting angles are preferably electrically nonconductive as is the 
expanded metal support grid. This can be achieved with metal angles and 
grids by coating them with a nonconductive material or, in the 
alternative, fabricating them from a nonconductive composite or the angles 
from ceramic material. 
In another embodiment, the absorber is convered with a soft flexible 
coating such as synthetic or natural rubber latex to keep out water or 
other contaminants.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT 
Referring now to FIG. 1, the embodiment chosen for purposes of illustration 
includes an acoustical absorber 10 and a generally U-shaped section 30 
into which the absorber 10 is to be installed. The U-shaped section is an 
elongated rigid structure having straight side walls 32, 34 connected by 
curved back wall 36. A pair of angles 38, 40 running the length of the 
section 30 are fixed to side walls 32, 34, respectively, at directly 
opposed locations with their flanges 38a and 40a facing each other. 
The acoustical absorber 10 comprises a flexible grid 12 sandwiched between 
two open cell foam panels 14, 16. The absorber is the approximate size and 
shape of the U-shaped section 30 into which it is to be placed. More 
particularly, the absorber 10 has a curved top surface 18 that matches the 
curved back wall 36 and side edges 20, 22 with notches 24, 26 running the 
length of side edges 20, 22, respectively. The upper surfaces 24a, 26a of 
notches 24, 26 are designed to mate with the flanges 38a and 40a when the 
absorber is mounted in the U-shaped section 30. The lower surface 28 of 
the absorber is shown to be curved in the same manner as back wall 36 and 
with the proper finish the surface 28 can be made to look like the surface 
finish of back wall 36 or to generally match its surroundings. 
In the preferred embodiment an acoustically active fabric 17 is embedded in 
foam layer 16. The absorber 10 is covered with a soft flexible coating 11 
such as synthetic or natural rubber latex. 
FIG. 2 illustrates the installation of absorber 10 into U-shaped section 
30. First the notch 26 of side edge 22 is inserted over flange 40a while 
compressing the edge 20 of the absorber with a stiff bladed tool 29 by 
pivoting the tool against angle 38 in the direction of the arrows 25, 27. 
At the same time a force is applied to surface 28 of the absorber 10 in 
between edges 20, 22 in the direction of arrow 23. This action allows the 
tool 29 and the side edge 20 of the absorber to be positioned with flange 
38a and foam layer 14 is compressed against back wall 36. The tool 29 is 
worked out of the section along the angle 38 and the return force from the 
foam layer 14 being compressed acts to push the support grid down from the 
center causing it to move outward over the flanges 38a and 40a to provide 
a positive support and causes the foam layers to conform to the walls of 
the section 30 as shown more clearly in FIGS. 3 and 4. 
The removal of an absorber is accomplished with two tools 29 which are 
inserted on the same side over angle 38 (angles 38 and 40 are shorter than 
the module to allow the tools to be inserted). The tools are pushed 
upwardly toward back wall 36 and rotated inwardly toward the center and at 
the same time the center of the absorber is pushed upwardly to relieve the 
pressure on grid 12. Then the absorber can be pulled inward and off angle 
38. 
While the detailed description disclosed a generally U-shaped structure 
with straight side walls and a curved back wall, other shapes such as 
rectangular channel and concave as shown in FIGS. 5 and 6 are intended to 
be included as generally U-shaped structures. More particularly, FIG. 5 
shows a rectangular channel section 30' as the receptor for absorber 10' 
which is the approximate size and shape of the receptor. In this case 
surface 28' of the absorber is flat. FIG. 6 shows a concave receptor 30" 
with absorber 10" installed therein. Surface 28" is slightly convex. These 
are some alternate embodiments which could be applied to either wall or 
ceiling receptors of the same design.