U.S. patent application number 11/080739 was filed with the patent office on 2005-09-15 for cushion.
This patent application is currently assigned to Tempur World, LLC. Invention is credited to Landvik, Dag.
Application Number | 20050202214 11/080739 |
Document ID | / |
Family ID | 27758688 |
Filed Date | 2005-09-15 |
United States Patent
Application |
20050202214 |
Kind Code |
A1 |
Landvik, Dag |
September 15, 2005 |
Cushion
Abstract
A support cushion including a first underlying layer made from a
flexible foam, at least one side of the first underlying layer
being configured with a non-plane surface. The support cushion also
includes a second underlying layer made from a flexible foam, at
least one side of the second underlying layer being configured with
a non-plane surface. The second underlying layer is placed in
abutment with the first underlying layer. The support cushion
further includes an overlying layer placed in abutment with the
second underlying layer, the overlying layer being made from a
visco-elastic foam.
Inventors: |
Landvik, Dag; (Saltsjo Boo,
SE) |
Correspondence
Address: |
Timothy M. Kelley
Michael Best & Friedrich LLP
100 East Wisconsin Avenue
Milwaukee
WI
53202-4108
US
|
Assignee: |
Tempur World, LLC
Lexington,
KY
|
Family ID: |
27758688 |
Appl. No.: |
11/080739 |
Filed: |
March 15, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11080739 |
Mar 15, 2005 |
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10379889 |
Mar 5, 2003 |
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6866915 |
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10379889 |
Mar 5, 2003 |
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09758018 |
Jan 10, 2001 |
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6602579 |
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Current U.S.
Class: |
428/180 ;
428/179 |
Current CPC
Class: |
Y10T 428/24669 20150115;
Y10T 428/24996 20150401; B32B 3/30 20130101; Y10T 428/24562
20150115; Y10T 428/24992 20150115; Y10T 428/24612 20150115; Y10T
428/249981 20150401; B32B 5/32 20130101; Y10T 428/24967 20150115;
B32B 27/40 20130101; B32B 2471/04 20130101; Y10T 428/24512
20150115; Y10T 428/24496 20150115; Y10T 428/24678 20150115; B32B
2307/51 20130101 |
Class at
Publication: |
428/180 ;
428/179 |
International
Class: |
B32B 003/28 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 11, 2000 |
DK |
DK PA 2000 00027 |
Claims
I claim:
1. A support cushion comprising: a first underlying layer made from
a flexible foam, at least one side of the first underlying layer
being configured with a non-plane surface; a second underlying
layer made from a flexible foam, at least one side of the second
underlying layer being configured with a non-plane surface, the
second underlying layer being placed in abutment with the first
underlying layer; and an overlying layer placed in abutment with
the second underlying layer, the overlying layer being made from a
visco-elastic foam.
2. The support cushion of claim 1, wherein the side of the first
underlying layer configured with the non-plane surface is placed in
abutment with a side of the second underlying layer configured with
a plane surface.
3. The support cushion of claim 1, wherein the non-plane surface of
at least one of the first and second underlying layers includes
truncated cones.
4. The support cushion of claim 3, wherein the truncated cones have
a height between about 15 mm and 30 mm.
5. The support cushion of claim 3, wherein the truncated cones have
tops, such that a mutual spacing between about 30 mm and 70 mm
exists between the tops of the truncated cones.
6. The support cushion of claim 1, wherein at least one of the
first and second underlying layers includes at least one side
having the non-plane surface configured in a continuous
pattern.
7. The support cushion of claim 1, wherein the second underlying
layer is joined together with the first underlying layer by fusing
a side of the second underlying with a side of the first underlying
layer.
8. The support cushion of claim 1, wherein the second underlying
layer is joined together with the first underlying layer by gluing
a side of the second underlying with a side of the first underlying
layer.
9. The support cushion of claim 1, wherein the overlying layer is
placed in abutment with the side of the second underlying layer
configured with the non-plane surface.
10. The support cushion of claim 1, wherein the overlying layer is
joined together with the second underlying layer by fusing a side
of the overlying layer with a side of the second underlying
layer.
11. The support cushion of claim 1, wherein the overlying layer is
joined together with the second underlying layer by gluing a side
of the overlying layer with a side of the second underlying
layer.
12. The support cushion of claim 1, further comprising a top layer
placed in abutment with the overlying layer, wherein the top layer
is made from a visco-elastic foam.
13. The support cushion of claim 12, wherein the top layer has a
thickness between about 15 mm and 35 mm.
14. The support cushion of claim 12, further comprising a total
thickness of the first underlying layer, the second underlying
layer, the overlying layer, and the top layer being between about
220 mm and 280 mm.
15. The support cushion of claim 14, wherein the total thickness is
between about 240 mm and 260 mm.
16. The support cushion of claim 12, wherein the overlying layer
and the top layer have substantially equal densities.
17. The support cushion of claim 12, wherein the density of each of
the top layer and the overlying layer is between about 50
kg/m.sup.3 and 100 kg/m.sup.3.
18. The support cushion of claim 17, wherein the density of each of
the top layer and the overlying layer is between about 80
kg/m.sup.3 and 90 kg/m.sup.3.
19. The support cushion of claim 1, wherein the overlying layer has
a hardness between about 60 N and 100 N.
20. The support cushion of claim 1, wherein the first and second
underlying layers are made from a highly elastic polyurethane foam
material.
Description
RELATED APPLICATIONS
[0001] Priority is hereby claimed to U.S. patent application Ser.
No. 10/379,889 filed on Mar. 5, 2003, U.S. patent application Ser.
No. 09/758,018 filed on Jan. 10, 2001, and Danish Patent
Application Number PA 2000 00027 filed on Jan. 11, 2000, the entire
contents of which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates generally to cushions, and more
particularly to cushions including bed mattresses, seat cushions,
back rest cushions, or any other cushion for supporting a body in
part or its entirety.
BACKGROUND OF THE INVENTION
[0003] A typical cushion uses elastic foam material for suitably
distributing pressure from the body over a relatively large surface
area of the body being supported by the cushion, such as a person
lying on a mattress, a person seated in a couch, or an animal
resting on a veterinary surgeon's table.
[0004] When used in combination with some type of less elastic
overlying layer, the elastic foam underlying layer in the cushion
counteracts the deepest depressed parts in the overlying layer in
order to provide an increased counter-pressure against the body. To
achieve a reasonably limited cushion thickness, the underlying
layer is typically arranged in the form of a highly-elastic foam
layer or a spring base with mechanical springs to provide suitable
support to the user.
SUMMARY OF THE INVENTION
[0005] The present invention provides a support cushion including a
first underlying layer made from a flexible foam, at least one side
of the first underlying layer being configured with a non-plane
surface. The support cushion also includes a second underlying
layer made from a flexible foam, at least one side of the second
underlying layer being configured with a non-plane surface, the
second underlying layer being placed in abutment with the first
underlying layer. Further, the support cushion includes an
overlying layer placed in abutment with the second underlying
layer, the overlying layer being made from a visco-elastic
foam.
[0006] By the present invention it has been realized that the
non-plane surface on such a flexible foam element constitutes an
ideal underlying layer for an overlying layer of the visco-elastic
foam, in that such an underlying layer with a non-plane surface of
truncated cones, among other shapes, are able to display an ideal
spring characteristic in supporting the overlying layer, which in
itself distributes and smoothes out the direct counter-pressure
from tops of the non-plane surface.
[0007] Further, it has been realized by the present invention that
dual flexible foam elements serving as underlying layers to an
overlying layer of visco-elastic foam provides additional benefits
in supporting the overlying layer. Such benefits, among others,
include providing a more consistent firmness over the cushion's
useful life.
[0008] Additional features and advantages of the present invention
will become apparent to those skilled in the art upon review of the
following detailed description, claims and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] In the drawings, wherein like reference numerals indicate
like parts:
[0010] FIG. 1 illustrates a sectional view of a one construction of
a cushion according to the present invention;
[0011] FIG. 2 illustrates a sectional view of another construction
of the cushion according to the present invention;
[0012] FIG. 3 is a graphical representation showing a relationship
between applied load and resultant strain of highly elastic
polyurethane foam;
[0013] FIG. 4 is a graphical representation showing a relationship
between applied load and resultant strain of a visco-elastic
foam;
[0014] FIG. 5 is a graphical representation showing a relationship
between applied load and resultant strain of a combination of
highly elastic polyurethane foam and visco-elastic foam;
[0015] FIG. 6 is a graphical representation showing a relationship
between applied load and resultant strain of a combination of
highly elastic polyurethane foam having a non-plane surface and
visco-elastic foam; and
[0016] FIG. 7 illustrates a sectional view of yet another
construction of the cushion according to the present invention.
[0017] Before the embodiments of the invention are explained in
detail, it is to be understood that the invention is not limited in
its application to the details of construction and the arrangements
of components set forth in the following description or illustrated
in the drawings. The invention is capable of other embodiments and
of being practiced or of being carried out in various ways. Also,
it is to be understood that the phraseology and terminology used
herein is for the purpose of description and should not be regarded
as limited.
DETAILED DESCRIPTION
[0018] Visco-elastic foam assumes the form--in a somewhat
"reluctant" manner--of the shape of the body being supported by the
visco-elastic foam. After assuming the form of the body, the
visco-elastic foam returns in a correspondingly "reluctant" manner
to its original form when the pressure from the body is removed. A
general definition of a visco-elastic foam may be ascertained from
the following scenario: A rigid object, such as a steel ball, is
dropped vertically downwards from a height of 1 m onto a plane
surface of the visco-elastic foam resulting in an upward rebound of
the rigid object of less than 10%, i.e., a rebound of less than 10
cm upwards from the plane surface of the visco-elastic foam.
[0019] The visco-elastic foam thus exercises only a modest elastic
counter-pressure against that surface by which it is loaded, and
for precisely this reason it will therefore allow the body to sink
relatively deeply into the cushion in such a manner to distribute
its overall counter-pressure over a large area of the body, with a
relatively uniform and relatively low counter-pressure per unit
area of the supported area of the body.
[0020] When utilized in cushions, the visco-elastic foam is
intended especially to alleviate or counteract sores such as
bedsores (decubitus) obtained from high-pressure points when lying
on a mattress for long periods of time. Such high-pressure points
may be generated by the highly-elastic foam layer or the spring
base with mechanical springs supporting the weight of the body.
Thus, it is desirable to limit the poor pressure distribution of
the highly-elastic foam utilized in a typical cushion.
[0021] The cushions shown in FIGS. 1-2 are both illustrated with an
underlying layer 2, which consists of a highly-elastic polyurethane
foam configured with a non-plane surface pattern of upright
truncated cones 4. Other patterns may be used such as ribs
extending in any chosen direction or a combination of cone-like
patterns and rib-like patterns. Still other surfaces may be bulges
having an oval or a rectangular shape or bulges having any other
separately designed and chosen shape.
[0022] The underlying layer 2 may have a thickness T2, which
includes the height H of the cones 4, of e.g., between about 50-150
mm. However, in some constructions of the underlying layer 2, the
height T2 is between about 110-120 mm. Further, in yet other
constructions of the underlying layer 2, the height T2 is between
about 70-80 mm. Also, in some constructions of the cones 4, the
height H is between about 15-30 mm. In other constructions of the
cones 4, the height H is between about 20-25 mm. The cones 4 may
also have a mutual spacing S of e.g., 30-70 mm, but more preferably
about 50 mm. The cones 4 can be formed by a known technique by
which a plane splitting of a foam block is carried out with the
opposing outer sides compressed in a corresponding pattern.
[0023] In the constructions illustrated in FIGS. 1-2, only one side
of the underlying layer 2 is construed with the truncated cones 4.
Alternatively, it is possible to have both sides of the underlying
layer 2 construed with truncated cones 4. Also, the mutual spacing
S between the truncated cones 4 may vary so that the mutual spacing
S between the truncated cones 4 is different along one part of the
underlying layer 2 as compared to other parts of the underlying
layer 2. This may be especially advantageous if the cushion is to
support bodies exerting different pressures at different locations
on the cushion. Accordingly, there may be parts of the underlying
layer 2 not having any truncated cones 4 at all and thus being
plane. Finally, the height H of the truncated cones 4 may vary
along the underlying layer 2 so that parts of the underlying layer
2 are construed with cones 4 with one height and other parts of the
underlying layer 2 being construed with cones 4 of another
height.
[0024] An overlying layer 6 having a thickness T6 of e.g., between
about 50-90 mm, but more preferably about 70 mm, is placed above
the underlying layer 2 with a lower surface of the overlying layer
6 resting on the tops of the cones 4. Preferably, the overlying
layer 6 is fastened to the cones 4 by fusing, or gluing together or
any other suitable mutual mechanical bonding between the overlying
layer 6 and the cones 4. The overlying layer 6 is made of a
visco-elastic foam material with suitable density and hardness,
such as the material marketed under the name Tempur.RTM..
[0025] As shown in FIG. 2, a top layer 8 is placed onto the
overlying layer 6 and preferably bonded to the overlying layer 6.
The top layer 8 has a thickness T8 smaller than the thickness T6 of
the overlying layer 6. The top layer thickness T8 is between about
15-35 mm. However, in some constructions of the top layer 8, the
top layer thickness T8 is about 20 mm, while in other constructions
of the top layer 8, the top layer thickness T8 is about 30 mm. Like
the overlying layer 6, the top layer 8 is also made of a
visco-elastic material such as the material marketed under the name
Tempur.RTM.. However, the top layer 8 is more preferably made of a
softer visco-elastic material than that of the overlying layer 6.
Thus, the overall thickness of the cushion illustrated in FIG. 2 is
between about 120-280 mm, but most preferably about 210 mm.
[0026] The terms, "underlying layer," "overlying layer," and "top
layer" are meant to describe the position of the individual layers
2, 6, 8 in relation to each other. Thus, the terms are not to be
construed as the underlying layer 2 being a layer, relative to an
upward and downward orientation, lying beneath the overlying layer
6. It is meant as a layer lying on the farthest side of the cushion
in relation to the body of the user. Similarly, the top layer 8, if
a top layer is provided, is a layer lying on the nearest side of
the cushion in relation to the body of the user. If the cushion,
for example, is mounted on a back rest, then the underlying layer,
the overlying layer and the top layer, if provided, will be
orientated sideways and not downwards and upwards,
respectively.
[0027] Also, the term body should not be construed as only the
whole body of the user. The body may be any part of the body such
as a head if the cushion is used as a pillow, the buttocks if the
cushion is used as a seat, or the back if the cushion is used as a
back rest. However, the cushion may also support the whole body if
the cushion is used as a mattress.
[0028] Furthermore, in the constructions shown in FIGS. 1-2, the
overlying layer 6 is in abutment with the underlying layer 2 along
a side of the underlying layer 2 being construed with the truncated
cones 4, the truncated cones 4 thus being directed toward the
overlying layer 6. Alternatively, the overlying layer 6 could be in
abutment with the side of the underlying layer 2 not being
construed with the truncated cones 4, the truncated cones 4 thus
being directed away from the overlying layer 6 and toward a firm
support such as the bottom of a bed if the cushion is a mattress,
or the back rest of a chair if the cushion is used as a back
rest.
[0029] The hardness of the highly elastic underlying layer 2 should
be between about 100-2000 N, measured in accordance with ISO 2439,
and the density should typically be between about 30-40 kg/m.sup.3.
The visco-elastic layers, i.e., the overlying layer 6 and the top
layer 8, have a density between about 50-100 kg/m.sup.3, more
preferably about 85 kg/m.sup.3, and a hardness of between about
60-100 N, more preferably between about 70-85 N, with the top layer
8 being somewhat softer than the overlying layer 6.
[0030] FIGS. 3-6 are graphic representations showing test results
from a test made according to ISO 2439 (Method B), where a sample
of foam material is subjected to a load from a circular piston. The
circular piston has a plane end surface and the relation between
the load from the piston and the corresponding strain is measured.
The test involves three initial compressions to a strain of 70% of
the initial height of the sample. The three initial compressions
are intended for obtaining a representative sample, in which the
sample has been subjected to a number of compressions before the
actual tests are made. Thereby the sample is preloaded, which
primarily has the effect that any crushing of a number of foam
cells is established before the actual test is performed.
[0031] As can be seen in all of the graphic representations the
first initial compressions are the highest lying of the curves.
This is due to the fact that a number of foam cells are not yet
crushed, which makes the foam "harder" and more "brittle," i.e., a
higher load is necessary for obtaining a certain strain. The
subsequent second and third initial compressions are the curves
lying below the first mentioned curve. This is due to the fact that
most of the number of foam cells have been crushed during the first
initial compression and just a few foam cells are being crushed
during the subsequent initial compressions.
[0032] Thus, the highest lying three curves are the three initial
compressions when applying the load to the sample. When relieving
the load, the relation between the load and the strain is
illustrated by the lowest lying curves decreasing along a
substantially vertical part of the curve from 70% strain at maximum
load and flattening out to a substantially horizontal part of the
curve towards 0% strain at a load of 0 N. The difference between
the relation between load and strain when applying the load and
when relieving the load is due to hysteresis in the foam
material.
[0033] After the three initial compressions have been carried out,
the sample is now mechanically stable and may now be subjected to
the actual compression test. The actual test is the curve having
the discontinuities where the load is decreasing at a certain
strain. The discontinuity is due to the test procedure where a load
is applied by pushing the piston first to a strain of 25% during
which the strain is maintained for a period of 30 seconds. During
the maintenance of the strain, the load necessary for maintaining
the strain is decreasing which is illustrated as a decrease of the
load in relation to the actual strain of 25%. The same procedure is
used at a strain of 40% and at a strain of 65%. The reason for the
load decreasing is the actual elastic behavior of the foam, where
both the highly elastic and the visco-elastic foam exhibit a
viscous behavior. In the following, the four samples will be
described in the table below and the actual compression test, not
the initial compressions, will be discussed.
1 Initial Batch reference & height 25% strain 40% 65% Sample
reference (mm) (N) strain (N) strain (N) FIG. 3: HE35N 50.8 112.4
152.3 308.5 Mattress with plane surface FIG. 4: T85-13 50.6 58.0
76.6 141.2 Mattress with plane surface FIG. 5: HE35N + T85-13 151.0
102.7 177.3 374.3 Mattress with plane interface FIG. 6: HE35N +
85-13 146.0 77.2 132.6 290.2 Mattress with non-plane interface
[0034] FIG. 3 shows the relation between load and strain for
commonly known highly elastic foam. Initially, the load applied is
high in relation to the strain obtained. At a strain of about 8%
the relation between the load and the strain decreases. At a strain
of about 50% the relation between the load and the strain
increases. Accordingly, there is a very uneven relation between the
load and the strain during compression up to 65% strain, however
the load carried being very high in relation to the strain caused
by the load.
[0035] FIG. 4 shows the relation between load and strain for known
visco-elastic foam. Initially, the load applied is high, but
limited, in relation to the strain obtained. At a strain of about
8% the relation between the load and the strain decreases. The
relation between the strain and the load is substantially the same
up to the strain of 65%. Accordingly, there is a much more even
relation between the load and the strain during compression up to
65% strain, however the load carried being very limited in relation
to the strain caused by the load.
[0036] FIG. 5 shows the relation between load and strain for a
combination of common highly elastic foam and a known visco-elastic
foam, where the interface between the foams is established between
a plane upper surface of the highly elastic foam and a planer lower
surface of the visco-elastic foam. The total thickness of the
mattress is 151.0 mm, where the thickness of the highly elastic
foam is about 80 mm and the thickness of the visco-elastic foam is
about 70 mm. The difference between the individual thicknesses and
the total thickness is established during the mutual bonding of the
two layers of foam, where fusing together the two layers may cause
the interface to create the difference.
[0037] Initially, the load applied is high, but somewhat limited,
in relation to the strain obtained. At a strain of about 4% the
relation between the load and the strain decreases. At a strain of
about 50% the relation between the load and the strain increases.
Accordingly, there is still a somewhat uneven relation between the
strain and the load during a compression up to 65% strain, however
the load carried being relatively high due to the highly elastic
foam and the relation being somewhat more even due to the
visco-elastic foam.
[0038] FIG. 6 shows the relation between load and strain for a
combination of highly elastic foam having a non-plane surface and a
known visco-elastic foam, where the interface between the foams
thus is non-plane. The surface of the highly elastic foam is
provided with a cone-like surface. The total thickness of the
mattress is 146.0 mm, where the thickness of the highly elastic
foam still is about 80 mm and the thickness of the visco-elastic
foam still is about 70 mm. The difference between the individual
thickness and the total thickness is established during the mutual
bonding of the two layers of foam, where tops of the cone-like
surface are partly disintegrated when fusing the two layers
together.
[0039] Both initially and during substantially the entire
application of load the relation between the load and the strain is
substantially linear. The relation between the load and the strain
increases very little until after a strain of above 50% is
obtained. Accordingly, there is a substantially linear relation
between the load and the strain during the entire compression up to
65% strain due to the non-plane surface of the highly elastic
surface and the consequently new interface between the highly
elastic foam and the visco-elastic foam. Also, the load carried is
relatively high due to the highly elastic foam and, as mentioned,
the relation between the load and the strain is completely even due
to the new combination of the non-plane surface of the highly
elastic foam and the visco-elastic foam.
[0040] The invention has been described with reference to tests
made to specific samples of highly elastic foam and of
visco-elastic foam and two combinations of these. However, both the
type of highly elastic foam and the type of visco-elastic foam, the
dimensions of the foams and the combinations of the foams may be
different, without departing from the scope of protection, where
the highly elastic foam has an uneven surface, which preferably is
the surface bonded to a surface of a visco-elastic foam. Only by
combining the highly elastic foam having an uneven surface with the
visco-elastic foam is it possible to obtain results as the ones
shown in FIG. 6, i.e., a substantially linear relation between the
load and the strain resulting in a substantial increase in user
comfort for the user lying, sitting or resting against the cushion,
but still maintaining a satisfactory high load carrying
capacity.
[0041] Yet another construction of the cushion is illustrated in
FIG. 7. In this construction, a second underlying layer 10 is used
in combination with the cushion of FIG. 2. Like the first
underlying layer 2, the second underlying layer 10 may have a
thickness T10, which includes the height H2 of the cones 12, of
e.g., between about 50-150 mm. However, in some constructions of
the second underlying layer 10, the height T10 is between about
110-120 mm. Further, in yet other constructions of the second
underlying layer 10, the height T10 is between about 70-80 mm.
Also, in some constructions of the cones 12, the height H2 is
between about 15-30 mm. In other constructions of the cones 12, the
height H2 is between about 20-25 mm. The cones 12 may also have a
mutual spacing S2 of e.g., 30-70 mm, but more preferably about 50
mm. Alternatively, in yet other constructions of the underlying
layers 2, 10, the heights H, H2 of the cones 4, 12 may be different
for each underlying layer 2, 10. Also, in other constructions of
the underlying layers 2, 10, the spacings S, S2 of the cones 4, 12
may be different for each underlying layer 2, 10.
[0042] In the construction illustrated in FIG. 7, only one side of
the second underlying layer 10 is construed with the truncated
cones 12. Alternatively, it is possible to have both sides of the
second underlying layer 10 construed with truncated cones 12. Also,
the mutual spacing S2 between the truncated cones 12 may vary so
that the mutual spacing S2 between the truncated cones 12 is
different along one part of the second underlying layer 10 as
compared to other parts of the second underlying layer 10. This may
be especially advantageous if the cushion is to support bodies
exerting different pressures at different locations on the cushion.
Accordingly, there may be parts of the second underlying layer 10
not having any truncated cones 12 at all and thus being plane.
Finally, the height H2 of the truncated cones 12 may vary along the
second underlying layer 10 so that parts of the second underlying
layer 10 are construed with cones 12 with one height and other
parts of the second underlying layer 10 being construed with cones
12 of another height.
[0043] In the construction of FIG. 7, the cones 12 of the second
underlying layer 10 are fastened to the planar side of the
underlying layer 2 by fusing, gluing, or any other suitable mutual
mechanical bonding between the underlying layers 2, 10. Thus, the
overall thickness of the cushion of FIG. 7 is between about 210-370
mm, more preferably between about 220-280 mm, and most preferably
about 250 mm.
[0044] A series of load-deflection tests were performed on both
cushion constructions of FIG. 2 and FIG. 7 to determine the
respective firmness of each cushion after repeated loading cycles.
Initial load deflection measurements were obtained using a 13.5"
circular platen prior to placing each cushion on a hexagonal roller
machine, which performed the repeated loading cycles. During the
tests, the hexagonal roller rolls across the width of each cushion
for 100,000 cycles in accordance with ASTM standard F1566-99 part
7. After testing each cushion, final load deflection measurements
were taken after approximately 1 hour of recovery time for each
cushion. Firmness measurements were also taken in association with
the load-deflection tests in accordance with ASTM standard F1566-99
part 6 "Firmness Rating"-center location. A contact force of 1 lb
was used for height measurements. The results of the
load-deflection tests are shown in the following table, in which
the cushion of FIG. 2 is labeled "Cushion A," and the cushion of
FIG. 7 is labeled "Cushion B":
2 Load Deflections Load (lbs) - Load (lbs) - After Before Test 100K
cycles % Difference Cushion Cushion Cushion Cushion Cushion Cushion
Deflection A B A B A B 0.5" 33.1 22.0 25.2 17.6 -23.9% -20.0% 1.0"
57.0 39.9 40.4 32.3 -29.1% -19.0% 1.5" 75.1 49.7 52.4 40.5 -30.2%
-18.5% 2.0" 94.7 60.0 67.5 49.2 -28.7% -18.0% 2.5" 117.7 73.1 89.6
60.4 -23.9% -17.4% 3.0" 150.8 90.8 122.7 76.0 -18.6% -16.3% Average
88.1 55.9 66.3 46.0 -24.7% -17.7% Height @ 1 lb 8.23" 10.39" 8.19"
10.30 -0.04" -0.09"
[0045] To interpret the results shown in the above table, a
negative % Difference value indicates that the cushion softened
after 100,000 loading cycles, and a positive % Difference value
indicates that the cushion hardened after 100,000 loading cycles.
However, the closer this value is to 0% the better, since the
consumer tends to expect the cushion to have the same relative
"feel" 5 to 10 years into the future as it did initially. It is
industry accepted that the % Difference value be under 25% in
either direction (+ or -). Also, it is generally accepted in
industry that 100,000 cycles of the hexagonal roller represents
approximately 10 years of use. With reference to the above table,
"Cushion B," exhibited an average -17.7% Difference value compared
to "Cushion A," which exhibited an average -24.7% Difference value.
Therefore, "Cushion B," which is the cushion construction including
multiple underlying layers 2, 10 (illustrated in FIG. 7), is better
able to maintain its "feel" after repeated loading cycles
equivalent to 10 years of actual use.
[0046] Variations and modifications of the foregoing are within the
scope of the present invention. It is understood that the invention
disclosed and defined herein extends to all alternative
combinations of two or more of the individual features mentioned or
evident from the text and/or drawings. All of these different
combinations constitute various alternative aspects of the present
invention. The embodiments described herein explain the best modes
known for practicing the invention and will enable others skilled
in the art to utilize the invention. The claims are to be construed
to include alternative embodiments to the extent permitted by the
prior art.
[0047] Various features of the invention are set forth in the
following claims.
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