Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02783982 2012-07-27
MATTRESS ASSEMBLY WITH HIGH AIRFLOW
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U. S. Provisional Application No.
61/513,090, filed July 29, 2011, incorporated herein by reference in its
entirety.
BACKGROUND
[0001] The present disclosure generally relates to foam mattress assemblies
exhibiting increased airflow.
[0002] Foam mattresses such as those formed of polyurethane foam, latex
foam, and the like, are generally known in the art. One of the ongoing
problems
associated with foam mattress assemblies is user comfort. To address user
comfort,
these mattresses are often fabricated with multiple foam layers having varying
properties such as density and hardness, among others, to suit the needs of
the
intended user. More recently, manufacturers have employed so called memory
foam,
also commonly referred to as viscoelastic foams, which are generally a
combination of
polyurethane and one or more additives that increase foam density and
viscosity,
thereby increasing its viscoelasticity. These foams are often open cell foam
structures
having both closed and open cells but in some instances may be reticulated
foam
structures. The term "reticulated" generally refers to a cellular foam
structure in
which the substantially all of the membrane windows are removed leaving a
skeletal
structure. In contrast, open cell structures include both open cell
(interconnected
cells) and closed cells.
[0003] When used in a mattress, the memory foam conforms to the shape of a
user when the user exerts pressure onto the foam, thereby minimizing pressure
points
from the user's body. The memory foam then returns to its original shape when
the
user and associated pressure are removed. However, the return to the original
shape is
a relatively slow process because of the viscoelastic cellular structure of
these types of
foams.
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[0004] Unfortunately, the high density of foams used in current mattress
assemblies, particularly those employing memory foam layers, generally
prevents
proper ventilation. As a result, the foam material can exhibit an
uncomfortable level
of heat to the user after a period of time. Additionally, these foams can
retain a high
level of moisture, further causing discomfort to the user and potentially
leading to foul
odors.
[0005] Reticulated memory foams, i.e., foams in which the cellular walls are
substantially removed, are known to provide greater airflow. However, because
substantially all of the cellular walls have been removed leaving behind a
skeletal
structure, these foams are inherently weak, provide less load-bearing
capabilities
relative to other non-reticulated viscoelastic foams, and are subject to
fatigue at a rate
faster than partially or completely closed cell foam structures. Moreover,
reticulated
viscoelastic foams require special processing to remove the cellular walls to
form the
skeletal structure making these foams relatively expensive.
[0006] Accordingly, it would be desirable to provide a mattress assembly,
especially a mattress including one or more layers of aviscoelastic memory
foam, with
an improved airflow to effectively dissipate user heat.
BRIEF SUMMARY
[0007] Disclosed herein are mattress assemblies exhibiting increased airflow.
In one embodiment, a mattress assembly comprises a non-viscoelastic first foam
layer
comprising planar top and bottom surfaces; a second foam layer overlaying top
planar
surface of the first foam layer, the second foam layer comprising a pre-
stressed foam
having planar top and bottom surfaces; and a viscoelastic third foam layer
overlaying
the top planar surface of the second foam layer, the second foam layer
comprising
planar top and bottom, wherein the viscoelastic third foam layer is the
uppermost layer
of the mattress assembly.
[0008] In another embodiment, a mattress assembly, comprises a non-
viscoelastic first foam layer having top and bottom planar surfaces; a non-
viscoelastic
second foam layer overlaying the top planar surface of the non-viscoelastic
first foam
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layer having planar top and bottom surfaces; a viscoelastic third foam layer
overlaying
the top planar surface of the second foam layer having planar top and bottom
surfaces;
and a viscoelastic fourth foam layer overlaying the top planar surface of the
third foam
layer, wherein the fourth foam layer is the uppermost layer of the mattress
assembly.
[0009] In yet another embodiment, a mattress assembly comprises a non-
viscoelastic first foam layer having planar top and bottom surfaces; a non-
viscoelastic
second foam layer overlaying the top planar surface of the first foam layer
having
planar top and bottom surfaces; a viscoelastic foam third layer overlaying the
top
planar surface of the second foam layer having planar top and bottom surfaces;
and a
gel infused viscoelastic fourth foam layer overlaying the top planar surface
of the
third foam layer having equal to or less than 50 percent by weight gel
loading; and a
viscoelastic fifth foam layer overlaying the top planar surface of the fourth
foam layer,
wherein the fifth foam layer is the uppermost layer of the mattress assembly.
[0010] The disclosure may be understood more readily by reference to the
following detailed description of the various features of the disclosure and
the
examples included therein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Referring now to the figures wherein the like elements are numbered
alike:
[0012] Figure 1 illustrates a top down view of a mattress assembly;
[0013] Figure 2 illustrates a cross sectional view of a mattress assembly
taken
along line 1-1 of FIG. I in accordance with an embodiment of the present
disclosure;
[0014] Figure 3 illustrates a cross sectional view of a mattress assembly
taken
along line 1-1 of FIG. 1 in accordance with an embodiment of the present
disclosure;
[0015] Figure 4 illustrates a cross sectional view of a mattress assembly
taken
along line 1-1 of FIG. I in accordance with an embodiment of the present
disclosure;
and
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[0016] Figure 5 illustrates a cross sectional view of a mattress assembly
taken
along line 1-1 of FIG. 1 in accordance with an embodiment of the present
disclosure.
DETAILED DESCRIPTION
[0017] Disclosed herein are mattress assemblies that provide user comfort
with improved airflow to effectively dissipate user heat during use. FIG. I
illustrates
a top down view representative of the various mattress assemblies, which are
generally designated by reference numeral 10. As will be discussed herein, the
various embodiments of the mattress assemblies disclosed herein have in common
the
following components: multiple stacked foam layers, wherein the uppermost foam
layer 12 is shown, a side rail assembly 14 about at least a portion of the
perimeter of
the stacked mattress layers, and an optional fabric covering 16 about at least
the side
rail assembly as shown, e.g., a mattress border. In some embodiments, the
optional
fabric covering may overlay the uppermost foam layer 12 and extend about the
perimeter. The uppermost foam layer 12 is generally referred to herein as the
cover
layer and has a planar top surface adapted to substantially face the user
resting on the
mattress assembly and having a length and width dimensions sufficient to
support a
reclining body of the user.
[0018] FIG. 2 shows a cross sectional view of a mattress assembly in
accordance with one embodiment. The mattress assembly 100 includes a base core
foam layer 102 configured with generally planar top and bottom surfaces. For
this as
well as the other embodiments disclosed herein, the core foam layer 102 is
chosen to
have a thickness greater than or equal to the overall thickness of the
mattress
assembly. Generally, the thickness of the foam core layer 102 is 4 inches to
10 inches,
with about 6 inches to 8 inches thickness in other embodiments, and about 6.5
inches
in still other embodiments. The core foam layer can be formed of standard
polyurethane foam although other foams can be used, including without
limitation,
viscoelastic foams. In one embodiment, the core foam layer is open cell
polyurethane
foam. In other embodiments, the core foam layer is closed cell polyurethane
foam.
The core foam layer 102 has a density of 1 pound per cubic foot (lb/ft3) to 5
lb/ft3. In
other embodiments, the density is 1 lb/ft3 to 3 lb/ft3 and in still other
embodiments,
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from 1 lb/ft3 to 2 lb/ft3. By way of example, the density can be 1.65 lb/ft3.
The
hardness of the core foam layer, also referred to as the indention load
deflection (ILD)
or indention force deflection (IFD), is within a range of 20 to 40 pounds-
force,
wherein the hardness is measured in accordance with ASTM D-3574 and is
generally
defined as the amount of force in pounds required to indent a 50" disc into a
15" x 15"
x 4" foam sample and make a 1" indentation. In one embodiment, the hardness is
about 32 to 35 pounds-force.
[0019] A relatively thin pre-stressed polyurethane foam layer 104 including
planar top and bottom surfaces is disposed on the base core foam layer 102.
Suitable
pre-stressed polyurethane foams are generally formed in the manner disclosed
in US
Pat. No. 7,690,096 to Gladney et al., incorporated herein by reference in its
entirety.
By way of example, a force can applied to at least a section of a standard
polyurethane
foam layer in an amount sufficient to temporarily compress its height so as to
permanently alter a mechanical property of the foam layer to provide a pre-
stressed
foam layer having a firmness that is different from the firmness of a similar
polyurethane foam that was not pre-stressed. The pre-stressed polyurethane
foam
layer is a standard polyurethane foam as noted above (i.e., not viscoelastic)
and
generally has a pre-stressed thickness of less than 1 inch to 0.5 inches. The
density is
generally less than 2.5 lb/ft3 to 0.5 lb/ft3 in some embodiments, and less
than 2 lb/ft3 to
1 lb/ft3 in still other embodiments. The hardness is generally less than 30
pounds-force
to 10 pounds-force in some embodiments, and less than 25 pounds-force to 15
pounds- force in still other embodiments. In one embodiment, the thickness is
0.5
inches, the hardness is 22 pounds-force, and the density is 1.5 lb/ft3.
[0020] A cover panel 106 is formed of a viscoelastic foam and disposed on the
polystyrene foam layer 104. The viscoelastic polyurethane foam in this
embodiment
as well as in the other embodiments disclosed herein where a viscoelastic foam
is
utilized in the mattress assembly has an open cell structure, wherein the
percentage of
intact windows (i.e., cell walls) between adjacent cells is less than 50
percent in one
embodiment, and less than 40 percent in other embodiments, and less than 30
percent
in still other embodiments. The cover panel 106 in this embodiment has planar
top
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and bottom surfaces. The thickness is generally less than 3 inches to 0.5
inches in
some embodiments, and less than 2 inches to 1 inch in other embodiments. The
density is less than 3 lb/ft3 to 1 lb/ft3 in some embodiments, and less than
2.5 lb/ft3 to
2 lb/ft3 in other embodiments. In one embodiment, the hardness is generally
less than
15 pounds-force to 5 pounds-force. In one embodiment, the cover panel is at a
thickness of 1.5", a density of 2.5 lb/ft3, and a hardness is 12 pounds-force.
[0021] The various multiple stacked mattress layers 102, 104, and 106 may be
adjoined to one another using an adhesive or may be thermally bonded to one
another
or may be mechanically fastened to one another.
[0022] The mattress assembly further includes a foam side rail assembly 120
about all or a portion of the perimeter of the mattress layers 102, 104, 106.
The side
rails that define the assembly may be attached or placed adjacent to at least
a portion
of the perimeter of the mattress layers 102, 104, 106, and may include metal
springs,
spring coils, encased spring coils, foam, latex, gel, viscoelastic gel, or a
combination,
in one or more layers. Side rails may be placed on opposing sides of the
stacked
mattress layers, on all four sides of the stacked mattress layers, or only on
one side of
the stacked mattress layers. In certain embodiments, the side rails may
comprise edge
supports with firmness greater than that provided by the stacked mattress
layers. The
side rails may be fastened to the stacked mattress layers via adhesives,
thermal
bonding, or mechanical fasteners.
[0023] In one embodiment, the side rail assembly is formed of a polyurethane
foam having a density generally less than 3 lb/ft3 and a hardness greater than
30
pounds-force. In one embodiment, the side rails are formed of having a density
of 1.65 lb/ft3 and a hardness of 45 pounds-force.
[0024] In another embodiment, the side rail assembly 120 is formed of open
cell polyurethane foam having a non-random large cell structure or a random
cellular
structure with many large cells. The large cell structure can be defined by
the number
of cells per linear inch. In one embodiment, the large cell structure is about
10 to 40
cells per inch, with about 15 to 30 cells per inch in other embodiments, and
with
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about 20 cells per inch in still other embodiments. The open cell foam
structure
includes a plurality of interconnected cells, wherein the windows between the
adjacent
cells are broken and/or removed. In contrast, in a closed cell foam there are
substantially no interconnected cells and the windows between the adjacent
cells are
substantially intact. In reticulated foams, substantially all of the windows
are
removed. By using an open cell structure with a large open cellular structure,
movement of moisture and air through a side rail can occur. Also, if the side
rail is
adhesively or thermally attached to the mattress layers, e.g., 102, 104, and
106, the
skeletal struts of the open cell foam will bond to the mattress layers,
thereby
facilitating air and moisture transfer from the mattress layers through the
side layers to
the environment. In one embodiment, the side rail assembly includes a
reticulated
viscoelastic polyurethane foam.
[0025] For ease in manufacturing the mattress assembly, the side rail assembly
may be assembled in linear sections that are joined to one another to form the
perimeter about the mattress layers. The ends may be square as shown in the
top
down view FIG. 1 or may be mitered.
[0026] An optional fabric layer 122 is disposed about the perimeter of the
side
rail, i.e., serves as a mattress border. The fabric border layer is attached
at one end to
the top planar surface of the uppermost mattress layer 106 and at the other
end to the
bottom planar surface of the bottom most layer 102. In one embodiment, at
least a
portion of the fabric layer is formed of a spacer fabric to provide a further
increase in
airflow. As used herein, spacer fabrics are generally defined as pile fabrics
that have
not been cut including at least two layers of fabric knitted independently
that are
interconnected by a separate spacer yarn. The spacer fabrics generally provide
increased breathability relative to other fabrics, crush resistance, and a
three
dimensional appearance. The at least two fabric layers may be the same or
different, i.e., the same or different density, mesh, materials, and like
depending on the
intended application. When employing the spacer fabric, a lightweight flame
retardant
barrier layer may be disposed intermediate to the mattress foam layers and the
spacer
fabric about the perimeter of the side rail assembly.
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[0027] In the embodiment shown, the mattress assembly 100 is generally less
than 12 inches in height. By way of example, an exemplary mattress assembly
illustrative of the embodiment shown in FIG. 2 has a 6.5" foam core layer of
standard
polyurethane foam having a density of 1.65 lb/ft3 and a hardness of about 32-
35
pounds-force ILD; a 0.5" pre-stressed polyurethane foam intermediate layer;
and 1.5"
top cover layer of viscoelastic polyurethane foam having a density of 2.5
lb/ft3 and a
hardness of about 12 pounds-force. The side rail assembly may have a thickness
of 2"
and is formed of an open cell foam having about 20 cells per linear inch as
described
above. A mattress border and panel of a spacer fabric is utilized as a
mattress border.
[0028] FIG. 3 shows a cross sectional view of a mattress assembly in
accordance with one embodiment. The mattress assembly 200 includes a base core
foam layer 202 configured with planar top and bottom surfaces. Generally, the
thickness of the foam core layer 202 is 4 inches to 10 inches, with about 6
inches to 8
inches thickness in other embodiments, and about 6.5 inches in still other
embodiments. The core foam layer can be formed of standard polyurethane foam
although other foams can be used, including without limitation, viscoelastic
foams. In
one embodiment, the core foam layer is an open cell polyurethane foam. In
other
embodiments, the core foam layer is closed cell polyurethane foam. The core
foam
layer 202 has a density of 1 lb/ft3 to 5 lb/ft3. In other embodiments, the
density
is 1 lb/ft3 to 3 lb/ft3 and in still other embodiments, from 1 lb/ft3 to 2
lb/ft3. By way of
example, the density can be 1.65 lb/ft3. The hardness of the core foam layer
is within
a range of 20 to 40 pounds-force. In one embodiment, the hardness is about 24
pounds-force.
[0029] A transition support layer 203 having planar top and bottom surfaces
and formed of standard polyurethane foam is disposed on the base core foam
layer 202. The transition support layer 203 generally has a thickness less
than 1 inch
to 0.5 inch, a density of less than 4 to 1 lb/ft3 , and a hardness less than
15 to 10
pounds-force. In one embodiment, the transition layer 203 has a thickness of
0.5", a
density of 3 lb/ft3, and a hardness of 12 pounds-force.
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[0030] Viscoelastic polyurethane foam layer 205 having planar top and bottom
surfaces overlyas on the transition support layer 203. The viscoelastic foam
layer 205
is generally characterized as having a thickness less than 1 inch, a density
of less than
3 to 1 lb/ft3, and a hardness less than 15 to 10 pounds-force. In one
embodiment, the
viscoelastic foam layer 205 has a thickness of 1", a density of about 2.5
lb/ft3, and a
hardness of 12 pounds-force.
[0031] A cover panel 206 formed of a viscoelastic foam is disposed on the
viscoelastic foam layer 205. The cover panel 206 has planar top and bottom
surfaces,
a density of 1 to 3.5 lb/ft3, a hardness of 10 to 15 pounds-force, and a
thickness of 1 to
2 inches. In one embodiment, the cover panel has a thickness of 1.5", a
density of
about 2.5 lb/ft3, and a hardness of about 12 pounds-force.
[0032] The mattress assembly may further include the side rail assembly 220
and the optional fabric border 222 as described above.
[0033] By way of example, an exemplary mattress assembly illustrative of the
embodiment shown in FIG. 3 has a 6.5" foam core layer of standard polyurethane
foam having a density of 1.65 lb/ft3 and a hardness of about 24 pounds-force
ILD;
a 0.5" transition support having a density of 3 lb/ft3 and a hardness of 12
pounds-
force; a 1" viscoelastic polyurethane foam layer having a density of 2.5
lb/ft3 and a
hardness of about 12 pounds-force; and a cover panel layer has a thickness of
1.5", a
density of about 2.5 lb/ft3, and a hardness of about 12 pounds-force. The side
rail
assembly may have a thickness of 2" and is formed of an open cell foam having
about 20 cells per linear inch as previously described. A mattress border and
panel of
a spacer fabric is utilized as a mattress border.
[0034] FIG. 4. shows a cross sectional view of a mattress assembly in
accordance with one embodiment. The mattress assembly 300 includes a base core
foam layer 302 configured with planar top and bottom surfaces. Generally, the
thickness of the foam core layer 302 is 4 inches to 10 inches, with about 6
inches to 8
inches thickness in other embodiments, and about 6.5 inches in still other
embodiments. The core foam layer 302 can be formed of standard polyurethane
foam
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although other foams can be used, including without limitation, viscoelastic
foams. In
one embodiment, the core foam layer is an open cell polyurethane foam. In
other
embodiments, the core foam layer is closed cell polyurethane foam. The core
foam
layer 302 has a density of 1 pound per square foot (lb/ft3) to 5 lb/ft3. In
other
embodiments, the density is 1 lb/ft3 to 3 lb/ft3 and in still other
embodiments,
from 1 lb/ft3 to 2 lb/ft3. By way of example, the density can be 1.65 lb/ft3.
The
hardness of the core foam layer is within a range of 20 to 40 pounds-force. In
one
embodiment, the hardness is about 24 pounds-force.
[0035] A transition support layer 303 having planar top and bottom surfaces
and formed of standard polyurethane foam is disposed on the base core foam
layer 302. The transition support layer 303 generally has a thickness of 0.5
to 1 inch,
a density of 1 to 4 lb/ft3, and a hardness of 10 toi 15 pounds-force. In one
embodiment, the transition layer 303 has a thickness of 0.5", a density of 3
lb/ft3, and
a hardness of 12 pounds-force.
[0036] Viscoelastic polyurethane foam layer 305 having planar top and bottom
surfaces is disposed on the transition support layer 303. The viscoelastic
foam
layer 305 is generally characterized as having a thickness of I to 3 inches, a
density of
I to 4 lb/ft3, and a hardness of 10 to 15 pounds-force. In one embodiment, the
viscoelastic polyurethane foam layer 305 has a thickness of 1.5", a density of
about
2.5 lb/ft3, and a hardness of 12 pounds-force.
[0037] A gel infused viscoelastic foam layer 307 having planar top and bottom
surfaces is disposed on the viscoelastic foam layer 305. Suitable gel infused
viscoelastic layers are generally disclosed in US Pat. No. 2010/0005595 to
Gladney et
al., which is incorporated by reference in its entirety. In one embodiment,
the gel
infused viscoelastic foam layer is infused with gel at less than about 50
percent by
weight in some embodiments, with less than 40 percent by weight in other
embodiments, and with less than 35 percent in still other embodiments.
Optionally,
the gel infused viscoelastic layer may be loaded with activated carbon for
odor
control. In one embodiment, the gel infused viscoelastic foam layer 307 is
formed of
a non-random open cell polyurethane viscoelastic foam having a thickness of
0.5 to 2
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inches, a density of 3 to 6 lb/ft3 and a hardness of 10 to 15 pounds-force. In
one
embodiment, the gel infused viscoelastic foam layer 307 has a 36 percent by
weight
gel loading, a density of 4.5 lb/.ft3, and a hardness of II pounds-force.
[0038] A cover panel 306 formed of a viscoelastic foam is disposed on the gel
infused viscoelastic foam layer 307. The cover panel 306 has planar top and
bottom
surfaces, a density of I to 3.5 lb/ft3, a hardness of 10 to 15 pounds-force,
and a
thickness of 0.5 to 2 inches. In one embodiment, the cover panel has a
thickness of
1.5", a density of about 2.5 lb/ft3, and a hardness of about 11 pounds-force.
[0039] The mattress assembly may further include the side rail assembly 320
and the optional fabric border 322 as described above.
[0040] By way of example, an exemplary mattress assembly illustrative of the
embodiment shown in FIG. 3 has a 6.5" foam core layer of standard polyurethane
foam having a density of 1.65 lb/ft3 and a hardness of about 24 pounds-force
ILD;
a 0.5" transition support having a density of 3 lb/ft3 and a hardness of 12
pounds-
force; a 1.5" viscoelastic polyurethane foam layer having a density of 2.5
lb/ft3 and a
hardness of about 12 pounds-force; a 1" gel infused viscoelastic foam layer
having
a 36 percent by weight gel loading, a density of 4.5 lb/.ft3, and a hardness
of 11
pounds-force; and a cover panel layer having a thickness of 1.5", a density of
about 2.5 lb/ft3, and a hardness of about 11 pounds-force. The side rail
assembly may
have a thickness of 2" and is formed of an open cell foam having about 20
cells per
linear inch as previously described. A mattress border and panel of a spacer
fabric is
utilized as a mattress border.
[0041] FIG. 5 shows a cross sectional view of a mattress assembly in
accordance with one embodiment. The mattress assembly 400 includes a base core
foam layer 402 configured with planar top and bottom surfaces. Generally, the
thickness of the foam core layer 402 is 4 inches to 10 inches, with about 6
inches to 8
inches thickness in other embodiments, and about 6.5 inches in still other
embodiments. The core foam layer 402 can be formed of standard polyurethane
foam
although other foams can be used, including without limitation, viscoelastic
foams. In
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one embodiment, the core foam layer is an open cell polyurethane foam. In
other
embodiments, the core foam layer is closed cell polyurethane foam. The core
foam
layer 302 has a density of 1 pound per square foot (lb/ft) to 5 lb/ft3. In
other
embodiments, the density is 1 lb/ft3 to 3 lb/ft3 and in still other
embodiments,
from 1 lb/ft3 to 2 lb/ft3. The hardness is within a range of 20 to 40 pounds-
force. By
way of example, the core layer 402 can have a thickness of 8", a density of
1.65 lb/ft3
and a hardness of 24 pounds-force.
[0042] A transition support layer 403 having planar top and bottom surfaces
and formed of standard polyurethane foam is provided on the base core foam
layer 402. The transition support layer 403 generally has a thickness less
than P, a
density of less than 4 lb/ft3, and a hardness less than 15 pounds-force. In
one
embodiment, the transition layer 403 has a thickness of 0.5", a density of 3
lb/ft3, and
a hardness of 12 pounds-force.
[0043] Viscoelastic polyurethane foam layer 405 having planar top and bottom
surfaces is disposed on the transition support layer 403. The viscoelastic
foam
layer 405 is generally characterized as having a thickness less than 3 inches,
a density
of less than 4.5 lb/ft3, and a hardness less than 15 pounds-force. In one
embodiment,
the viscoelastic polyurethane foam layer 405 has a thickness of 1.5", a
density of
about 3.5 lb/ft3, and a hardness of 11 pounds-force.
[0044] A gel infused viscoelastic foam layer 407 having planar top and bottom
surfaces is disposed on the viscoelastic foam layer 405. In one embodiment,
the gel
infused viscoelastic foam layer is infused with gel at less than about 50
percent by
weight in some embodiments, with less than 40 percent by weight in other
embodiments, and with less than 35 percent in still other embodiments.
Optionally,
the gel infused viscoelastic layer may be loaded with activated carbon for
odor
control. In one embodiment, the gel infused viscoelastic foam layer 407 is
formed of
a non-random open cell polyurethane viscoelastic foam having a thickness less
than 2 inches, a density generally less than 6 lb/ft3 and a hardness greater
than 15
pounds-force. In one embodiment, the gel infused viscoelastic foam layer 407
has a 36
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percent by weight gel loading, a density of 4.5 lb/.ft3, and a hardness of 11
pounds
force.
[0045] A cover panel 406 formed of a viscoelastic foam is disposed on the get
infused viscoelastic foam layer 407. The cover panel 406 has planar top
surface and a
convoluted bottom surface, a density less than 4.5 lb/ft3, a hardness less
than 15
pounds-force, and a thickness less than 2". The convoluted bottom surface is
in
contact with the top planar surface of the gel infused viscoelastic layer 307.
An
exemplary convoluted foam has an egg crate structure such as the one disclosed
in US
Pat. Pub. No. 2007/0226911 to Gladney et al., incorporated herein by reference
in its
entirety. In one embodiment, the cover panel has a thickness of 1.5", a
density of
about 3.5 lb/ft3, and a hardness of about 11 pounds-force.
[0046] The mattress assembly may further include the side rail assembly 420
and the optional fabric border 422 as described above.
[0047] By way of example, an exemplary mattress assembly illustrative of the
embodiment shown in FIG. 4 has a 8" foam core layer of standard polyurethane
foam
having a density of 1.65 lb/ft3 and a hardness of about 24 pounds-force ILD; a
0.5"
transition support having a density of 3 lb/ft3 and a hardness of 12 pounds-
force;
a 1.5" viscoelastic polyurethane foam layer having a density of 3.5 lb/ft3 and
a
hardness of about 11 pounds-force; a 1.5" gel infused viscoelastic foam layer
having
a 36 percent by weight gel loading, a density of 4.5 lb/.ft3, and a hardness
of 11
pounds-force; and a cover panel layer having a convoluted bottom surface, a
thickness
of 1.5", a density of about 3.5 lb/ft3, and a hardness of about 11 pounds-
force. The
side rail assembly may have a thickness of 2" and is formed of an open cell
foam
having about 20 cells per linear inch as previously described. A mattress
border and
panel of a spacer fabric is utilized as a mattress border.
[0048] The various mattress layers in the mattress assemblies described above
may be adjoined to one another using an adhesive or may be thermally bonded to
one
another or may be mechanically fastened to one another.
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[0049] This written description uses examples to disclose the invention,
including the best mode, and also to enable any person skilled in the art to
make and
use the invention. The patentable scope of the invention is defined by the
claims, and
may include other examples that occur to those skilled in the art. Such other
examples
are intended to be within the scope of the claims if they have structural
elements that
do not differ from the literal language of the claims, or if they include
equivalent
structural elements with insubstantial differences from the literal languages
of the
claims.
14
