Note: Descriptions are shown in the official language in which they were submitted.
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INFLATABLE BODIES HAVING IMPROVED RESISTANCE TO THERMAL
RADIATION TRANSMISSION
BACKGROUND OF THE INVENTION
Thermal performance data disclosed herein was obtained using a temperature
controlled test chamber held at 4 C in which prior art inflatable bodies and a
plurality
of inflatable bodies constructed according to the invention embodiments were
subjected to an insulated heat source (a three zone guarded heat plate
operatively
linked to a computer) on one side and heat sink (a large aluminum plate with a
plurality of temperature probes also linked to a computer) exposed to the
controlled
environment on the other side. The thermal performance of a subject mattress
was
then established by determining the amount of electrical power needed to
maintain
the heat source at a constant temperature of 33.3 C while also maintaining the
temperature of the heat sink at the ambient temperature. Once stabilized, the
amount of electrical power needed to maintain this steady state correlated
with the
heat energy passing from the heat source, through the subject mattress and
into the
heat sink, and ultimately rejected into the environment. In this manner, the
electrical
equivalent of the thermal transmission rate could be determined.
These tests indicated that prior art inflatable bodies comprising an expanded
polyurethane foam core co-extensively bonded to opposing panels have thermal
insulation values of about R-3 for 1" (-2.5 cm) thick cores, about R-5 for 2"
(-5.0 cm)
thick cores, and about R-7 for 3" (-7.5 cm) thick cores. These tests also
indicated
that conventional inflatable bodies such as non-baffled air mattresses of
about 2.5"
(-6.25 cm) thickness have a thermal insulation value of about R-1 when
constructed
from polymeric films of the type referenced herein. By introducing a
conventional
film-based bisecting baffle to compartmentalize "upper" and "lower" portions
of such
inflatable bodies, heat loss from thermal convection was significantly
reduced, as
reflected by a doubling of the thermal insulation value to about R-2.
However, if additional meaningful thermal insulation gains for such non-foam
core inflatable bodies are desired, it becomes necessary to address heat
transfer
modes other than thermal convection; since thermal conduction is not a
meaningful
contributor in such mattresses, the remaining mode is thermal radiant
transmission.
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To mitigate this mode of heat transfer, a metalized polymeric bisecting film
can be
substituted for the non-metalized bisecting film in the previously described
baffled
inflatable body, as is taught in the prior art. The result of this
substitution yields an increase
in thermal insulation performance of about one additional "R" value, e.g., to
about R-3,
when the film has a 1.0 optical density.
International publication number WO 2009094208 A2 discloses inflatable bodies
having a cellular matrix core comprised of various materials wherein
substitution of certain
matrix core components with metalized film and/or metalization of existing
materials
(whether planar, corrugating or panel) provides possible means for mitigating
heat transfer
via thermal radiation transmission through such inflatable bodies. While this
publication
does not disclose or suggest any details concerning such substitution or
treatment, it does
identify issues pertaining to compatible bonding interface requirements at
page 4. Still, it
offers no details concerning the inflatable body structure(s) to which it
would be bonded.
Moreover, there is no disclosure concerning which mode for mitigating heat
transfer via
thermal radiation transmission is preferable or more efficacious, other than
the disclosure
on pages 12 - 13:" ... a preferred embodiment of the invention comprises a
foam planar
sheet to which is selectively bonded at least one non-woven or batting-type
material as a
serpentine or corrugating sheet, and at least one envelope panel having a
radiant heat
transfer mitigation treatment thereon, preferably on an interior surface
thereof."
However, tests have shown that simply metalizing the flexible panels that
envelope
the cellular matrix cores of the inflatable bodies referenced in WO 2009094208
A2 do not
yield the degree of thermal performance improvement as expected, nor does
metallization
of the non-woven corrugating materials. And while substituting a metalized
polymeric film
having an optical density of about 1.0 for the bifurcating non-metalized film
resulted in an
increase of about + R-1 for the basic inflatable mattress, adding additional
bifurcating
metalized polymeric films having an optical density of about 2.0 only
increased thermal
performance by several tenths (+ R-0.6 for two films and + R-0.8 for three
films).
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,
As the above data show, progressively increasing the thickness of expanded
foam
cores in inflatable bodies yields a somewhat linear improvement in thermal
performance,
due to multiple thermal mitigation modalities inherent in expanded foam cores.
However,
simple "metallization" of such bodies or substantially open core inflatable
bodies does not
necessarily yield similar performance improvements. Moreover, the
incorporation of
metals and/or metalized materials into such bodies may also decrease the
overall thermal
performance of the inflatable body due to conduction by the metalized films
and/or treated
materials, and necessarily increases the weight of the inflatable body. As a
consequence,
the adage of "if one is good, then more must be better" does not necessarily
hold true.
SUMMARY OF THE INVENTION
Illustrative embodiments are directed towards inflatable bodies having
improved
means for mitigating thermal radiation transmission from one side of the
inflatable body to
an opposing side. The improved means, which broadly comprise the incorporation
of at
least one selectively linked and spaced apart intra-body radiant barrier,
yield unexpected
gains in thermal performance for inflatable bodies that otherwise might not
find utility in
certain environmental conditions, as will be described below.
As used herein, the generic usage of the term "inflatable body" refers to any
collapsible-inflatable fluid retaining structure, whether self-inflating or
not, comprising first
and second sides (whether formed from discrete sheets or panels, or a single
sheet or
panel of material) that at least partially define a substantially fluid
impermeable envelope
and that are selectively linked to each other by intra-envelope tensile means
(whether
directly by discrete members, or indirectly by a plurality of members or a
system of
members), i.e., the linkage occurs within the envelope. This selective linkage
of opposing
sides differs from inflatable bodies having substantially coextensive linkage
arrangements,
such as found in prior art self-inflatable bodies that rely upon open cell
foam cores that are
substantially bonded to both sides, like Cascade Designs' THERM-A-REST
mattresses:
when inflatable body embodiments according to the invention are inflated,
thereby causing
the opposing sides to
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separate or displace from each other, the degree of separation or displacement
is not
uniform over the opposing sides; the non-selectively linked portions of each
side are
permitted to distend from virtual plane comprising the selective linkage
locations. As
a result, the sides have surface contours or protrusions where one side is not
linked
to the opposing side. The first and second sides of inflatable body
embodiments of
the invention may be characterized as panels, each having an inner surface
presenting to the envelope and an outer surface presenting to the environment.
As used herein, collapsible cellular matrix cores found in several invention
embodiments comprise a plurality of generally geometrically identical cells
(hollow,
open-ended geometric prisms, each defining a major axis) that are formed or
linked
together to establish a repeating geometric pattern (a "row"), wherein the
major axes
of the prisms are generally perpendicular to a perimeter portion of the
inflatable body
and selective portions of the matrix ("linking locations") are directly or
indirectly
bonded to inner surfaces of opposing panels, whereby the matrix functions as
the
tensile means for the inflatable body.
In many invention embodiments, a plurality of substantially triangular hollow,
open-ended prisms comprises the cellular matrix, wherein at least each of some
prisms, but not all prisms, are defined by two portions of a corrugating film
or thin
sheet material such as a spun or non-woven filament batting and one portion of
a
generally planar film or thin sheet material such as a spun or non-woven
filament
batting. Thus, outer rows of the matrix generally comprise triangular prisms
alternating with open spaces that resemble "V" shaped channels. In other
words,
visually, the result is WWWWW for an arbitrary outer row. Prior to the instant
invention, the opposing panels that form the envelope for the inflatable body
would
cap or close the "V" shaped channels, thereby constituting a third wall for
substantially each of the other prisms in an outer row, when the outer facing
apexes,
which constitute linking locations, were bonded thereto.
Turning then to a first series of invention embodiments, an inflatable body
comprising a cellular matrix of the type referenced herein is augmented with
at least
one means for mitigating thermal radiation transmission, as herein described.
The
radiant barrier means of the various embodiments forming the several groups
within
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this series comprise at least one film-based, radiant barrier established
intermediate
the matrix and an otherwise adjacent inflatable body panel. Each such
intermediate
radiant barrier preferably has greater radiant energy reflectivity than any
other
conventional component of the inflatable body, i.e., non-specialized or non-
metalized
component.
Because of this intermediate position between the cellular matrix and the
panel, the intermediate radiant barrier (or in the case of plural intermediate
radiant
barriers, the inner most barrier) functions to establish the third wall of at
least some
triangular hollow, open-ended prisms as opposed to the adjacent or proximate
panel,
as the case may be, in conventional cellular matrix based inflatable bodies.
Nevertheless, the registry between the cellular matrix linking locations and
the panel
linking locations remains the same.
While the following descriptions of various invention embodiments within this
series establish preferred spatial relationships between the intermediate
radiant
barrier(s) and the otherwise adjacent panel, the actual means for mitigating
thermal
radiation transmission only requires the consequential result of such spatial
relationships, namely, the creation of an actual or potential space or void
between
the barrier(s) and the panel upon inflation of the inflatable body. Therefore,
the
distance in at least one direction between adjacent linking locations on an
intermediate radiant barrier maybe the as the distance between corresponding
linking
locations on the otherwise adjacent panel if a space or void between the panel
and
the intermediate radiant barrier can result after inflation of the inflatable
body. Such a
result may occur depending upon distortion of the cellular matrix upon
inflation and/or
differences between the mechanical properties of the matrix and the panel, as
well as
gravitational orientation.
With the preceding caveat in mind, a first group of invention embodiments
within this series comprise a single intermediate radiant barrier established
between
the cellular matrix and an adjacent body panel wherein the distance in at
least one
direction between adjacent linking locations on the intermediate radiant
barrier is less
than the distance between corresponding linking locations on the panel. As a
consequence of this arrangement, when the inflatable body is inflated, the
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intermediate radiant barrier is brought taught and the panel is urged and
permitted to
distend from the virtual plane comprising the linking locations, thereby
forming a
space or void between itself and the intermediate radiant barrier. Because
this
relative displacement results from inflation of the body, the space or void
formation is
independent of spatial orientation. In other words, the one body panel can be
arbitrarily the upper or lower panel of an inflatable body such as a mattress.
Additionally, such flexibility lends itself to application of an intermediate
radiant
barrier at each matrix-to-panel interface of the inflatable body.
An alternative to the foregoing embodiment has the distance in at least one
direction between adjacent linking locations on the intermediate radiant
barrier
greater than the distance between corresponding linking locations on the
panel. As a
consequence of this arrangement, when the panel is brought taught such as by
inflation of the inflatable body, the intermediate radiant barrier remains
slack and is at
least partially displaceable or separable from the adjacent panel, to thereby
form a
space or void there between. However, the space or void formation ability of
this
alternative arrangement is more dependent upon spatial orientation insofar as
gravity
may have a material effect thereon.
When a metalized polymeric film having an optical density of about 1.0
comprises the means for mitigating thermal radiation transmission in these
first series
embodiments, tests have shown an increase in thermal performance of the
inflatable
body of about + R-1. When this arrangement is duplicated on an opposing side
of
the inflatable body, and additional gain of about + R-1 was realized. An added
benefit of these arrangements is the establishment of additional body
compartmentalization, which further mitigates heat transfer due to convection.
In a second group of invention embodiments within this series, a plurality of
intermediate radiant barriers are established between the cellular matrix and
one
body panel. Extending upon either of the embodiments referenced above, each
additional intermediate radiant barrier is established inwardly (toward the
cellular
matrix) of a previous intermediate radiant barrier wherein the distance
between
adjacent linking locations in same direction as considered in the previous
intermediate radiant barrier is less than (or in the alternative greater than)
the
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distance between corresponding linking locations on the previous intermediate
radiant barrier. As a consequence of this arrangement and in the first
instance, when
the inner most intermediate radiant barrier (the one directly linked to the
cellular
matrix) is brought taught, such as by inflation of the inflatable body, the
panel is
urged and permitted to distend from the virtual plane comprising the linking
locations,
thereby forming a space or void between itself and the intermediate radiant
barriers.
Those intermediate radiant barriers between the inner most radiant barrier and
the
panel are then at least partially displaceable or separable from both the
inner most
radiant barrier and the panel. A similar outcome results from inflation of an
embodiment according to the alternative referenced above.
In addition to the increased compartmentalization of the inflatable body
comprising these second group arrangements, which as previously discussed
mitigates heat transfer due to convection, the creation of a space or void
between
adjacent intermediate radiant barrier films materially reduces heat transfer
that would
otherwise occur due to conduction and/or micro-convection. This finding, it is
believed, at least partially explains the progressively diminishing thermal
performance values when simply increasing the "metallization" of an inflatable
body.
In a second series of invention embodiments, a cellular matrix of the type
referenced herein for use with an inflatable body is augmented with at least
one
means for mitigating thermal radiation transmission, as herein described. The
radiant barrier means of the various embodiments within this series comprise
at least
one film-based, radiant barrier established intermediate two rows of
triangular hollow,
open-ended prisms that form part of the cellular matrix. As with the first
group of the
first series, the first group of this second series seeks to establish an
additional
element to the inflatable body as opposed to replacing and/or enhancing an
existing
element. Therefore, the present thermal radiation mitigation means, which is
preferably a film-based radiant barrier, is established between an existing
generally
planar film or thin sheet material such as a spun or non-woven filament
batting, itself
intermediate the two rows of prism, and an otherwise adjacent row of prisms.
Also
as with the first group of the first series, this radiant barrier functions to
establish the
third wall of at least some triangular hollow, open-ended prisms, but instead
with
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respect to the existing substantially planar film or sheet. As a consequence,
no prism
in one row shares a common enclosing wall with any prism in an adjacent row.
Because there are no common enclosing walls between rows of prisms, it is
possible, and considered preferable, to establish a space or void between
these two
intra-row elements, particularly if the existing substantially planar film or
sheet itself
can be characterized as mitigating thermal radiation transmission. Thus, the
distance in at least one direction between adjacent linking locations on the
intermediate radiant barrier is preferably less than, but can also be greater
than, the
distance between corresponding linking locations on the existing substantially
planar
film or sheet. If the existing substantially planar film or sheet is best
characterized
as a non-film, then equivalent distances are considered within the scope of
the
invention due to the different mechanical properties between the two
materials.
Finally, a third series of invention embodiments combines arrangements from
the first two, and represents a presently preferred embodiment. In particular,
an
inflatable body according to this series has a cellular matrix with radiant
barrier
means for mitigating thermal radiation transmission intermediate the cellular
matrix
and both opposing panels as well as intermediate two rows of triangular
hollow,
open-ended prisms. Test have shown that inflatable bodies having a thickness
of
about 2.5" (-6.25 cm) and comprising these modifications have thermal
insulation
values of about R-4.9. For comparison, a conventional inflatable mattress
having a
2" (-5.0 cm) thick piece of 0.9 density open cell polyurethane foam has a
comparable
"R" value, but weights almost five times more and, when manually compressed
for
storage, displaces about four times the volume. If the existing generally
planar film
or thin sheet material can be characterized as having thermal radiation
transmission
mitigation properties the same as or similar to that of the intermediate
radiant barrier,
then the thermal insulation value increases to about R-5.7.
The inflatable bodies described and shown herein are not limited to camping
mattresses, but may find utility in any application that can utilize many of
its key
properties: thermal management, compact storage, ease of deployment
(inflatable),
light weight and structural stability. Potential uses such as portable
structures or
tents, seating ,window shades, thermally insulated boxes or containers, water
cooling
8
and heating systems, cold-weather clothing, sleeping bags and systems, and
shock or
impact attenuation systems.
In one illustrative embodiment, an inflatable body includes first and second
substantially opposing side panels, substantially bonded to each other about a
common
periphery to at least partially define a substantially fluid impermeable
envelope. The
inflatable body further includes a cellular matrix disposed within the
envelope and having
at least two rows including hollow, open-ended geometric prisms, each prism
defining a
major axis. The prisms establish a repeating geometric pattern and are
separated by a
planar member having linking locations. The major axes of the prisms are
generally
perpendicular to the envelope periphery. Portions of the matrix are directly
or indirectly
bonded to inner surfaces of the opposing side panels at linking locations,
whereby the
matrix functions as tensile means for the inflatable body. The inflatable body
further
includes at least one means for mitigating thermal radiation transmission,
coupled to at
least one of the opposing side panels to define an air-filled chamber
exclusive of the
cellular matrix when the body is in an inflated state.
In another illustrative embodiment, an inflatable body includes first and
second
substantially opposing side panels, substantially bonded to each other about a
common
periphery to at least partially define a substantially fluid impermeable
envelope. The
inflatable body further includes a cellular matrix disposed within the
envelope and having
at least two rows comprising hollow, open-ended geometric prisms, each
defining a major
axis. The prisms establish a repeating geometric pattern and are separated by
a planar
member having linking locations. The major axes of the prisms are generally
perpendicular to the envelope periphery. Portions of the matrix are directly
or indirectly
bonded to inner surfaces of the opposing side panels at linking locations,
whereby the
matrix functions as tensile means for the inflatable body. The inflatable body
further
includes at least one thermal radiation transmission mitigation element,
directly coupled to
the planar member to define an air-filled chamber exclusive of the cellular
matrix when the
body is in an inflated state.
For purposes of this patent, the terms "area", "boundary", "part", "portion",
"surface",
"zone", and their synonyms, equivalents and plural forms, as may be used
herein and by
way of example, are intended to provide descriptive references or landmarks
with respect
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to the article and/or process being described. These and similar or equivalent
terms are
not intended, nor should be inferred, to delimit or define per se elements of
the referenced
article and/or process, unless specifically stated as such or facially clear
from the several
drawings and/or the context in which the term(s) is/are used.
Other aspects and features of illustrative embodiments will become apparent to
those ordinarily skilled in the art upon review of the following description
of such
embodiments in conjunction with the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view a prior art inflatable body having tensile means
in the
form of a cellular matrix, wherein opposing panels form a plurality of the
triangular, hollow
open-ended prisms that comprise the matrix;
Fig. 2 is a perspective view a first series embodiment of an inflatable body
wherein
an intermediate radiant barrier is established between the cellular matrix and
one panel;
Fig. 3 is a perspective view a derivative of the embodiment of Fig. 2, wherein
a
second intermediate radiant barrier is established between the cellular matrix
and an
opposing panel; and
Fig. 4 is a perspective view a derivative of the embodiment of Fig. 3, which
incorporates aspects of a second series embodiment, wherein a third
intermediate radiant
barrier is established between rows of prisms within the cellular matrix.
DESCRIPTION OF INVENTION EMBODIMENTS
Preface: The terminal end of any numeric lead line in the several drawings,
when
associated with any structure or process, reference or landmark described in
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this section, is intended to representatively identify and associate such
structure or
process, reference or landmark with respect to the written description of such
object
or process. It is not intended, nor should be inferred, to delimit or define
per se
boundaries of the referenced object or process, unless specifically stated as
such or
facially clear from the drawings and the context in which the term(s) is/are
used.
Unless specifically stated as such or facially clear from the several drawings
and the
context in which the term(s) is/are used, all words and visual aids should be
given
their common commercial and/or scientific meaning consistent with the context
of the
disclosure herein.
With the foregoing in mind, the following description is presented to enable a
person skilled in the art to make and use the claimed invention. Various
modifications to the described embodiments will be readily apparent to those
skilled
in the art, and the generic principles disclosed herein may be applied to
other
embodiments and applications thereof without departing from the spirit and
scope of
the present invention, as defined by the appended claims. Thus, the claimed
invention is not intended to nor should be limited to the disclosed and/or
described
embodiments, but is to be accorded the widest scope consistent with the
principles
and features disclosed herein.
Turning then to the several embodiments, wherein like numerals indicate like
parts, and more particularly to Figs. 1, prior art inflatable mattress 10 is
shown having
outer panels 20a and 20b, planar or bifurcating member 30 and corrugating or
serpentine members 40a and 40b. Together, these components form prisms 50,
which in the aggregate, create rows I and II. Each prism 50 further includes
three
linking locations, alternately two for linking with a panel 20a or 20b and one
for linking
with member 30, or one for linking with a panel 20a or 20b and two for linking
with
member 30. These linking locations correspond to complementary linking
locations
on the noted panels and member.
Figure 2 shows a modified version of mattress 10 according to one aspect of
the invention. Modified mattress 100 includes intermediate radiant barrier
60b, which
is established between row II and panel 20b. As illustrated, the distance
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linking locations of panel 20b is greater than the distance between linking
locations of
radiant barrier 60b, thereby forming spaces or voids 70b.
Figure 3 further modifies mattress 100 according to another aspect of the
invention. Modified mattress 200 includes intermediate radiant barrier 60a,
which is
established between row I and panel 20a. As illustrated, the distance between
linking locations of panel 20a is greater than the distance between linking
locations of
radiant barrier 60a, thereby forming spaces or voids 70a.
Finally, Fig. 4 further modifies mattress 200 according to another aspect of
the
invention. Modified mattress 300 includes intermediate radiant barrier 60c,
which is
established between planar or bifurcating member 30 and corrugating or
serpentine
members 40a of row I. As illustrated, the distance between linking locations
of planar
or bifurcating member 30 is less than the distance between linking locations
of
radiant barrier 60c, thereby forming spaces or voids 70c.
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