(12) United States Patent
`(10) Patent No.:
`US 6,244,458 B1
`
`Frysinger et al. (45) Date of Patent: Jun. 12, 2001
`
`
`U8006244458B1
`
`(54) THERMALLY INSULATED CONTAINER
`
`(75)
`
`Inventors: Clinton Frysingcr, Westerville; James
`Graber, Columbus; Dwight Musgrave,
`Granville; Linda Siders, Reynoldsburg;
`Gregory Thune, Westerville, all of OH
`(US); Dorothy J. Mufl'ett, Plymouth,
`MN (US); Joseph Lehman, Columbus,
`OH (US)
`
`2,019,194 * 10/1935 Munters .
`. 220/592.1
`.. 220/592.09
`2,304,757 * 12/1942 Arthur
`
`.. 220/592.09
`2,484,310 * 10/1949 Philip ,
`
`.. 220/592.09
`2,817,123 * 12/1957 Jacobs
`1/1961 Morrison
`. 220/592.2
`2,969,164 *
`7/1991 Glicksman et al.
`5,032,439 *
`428/44
`5,316,171 *
`5/1994 Danner, Jr. et a1.
`............ 220/592.21
`5,512,345 *
`4/1996 Tsutsumi et a1.
`..
`428/69
`5,816,432 * 10/1998 llammen et al.
`220/530
`
`5,918,478 *
`7/1999 Bostic et a1.
`62/371
`
`
`5,950,450 *
`9/1999 Meyer et a1.
`62/4579
`
`(73) Assignee: Thermo Solutions, Inc., Minneapolis,
`MN (US)
`
`* cited by examiner
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(21) Appl. No.: 09/347,663
`
`(22) Filed:
`
`Jul. 6, 1999
`
`(60)
`
`Related US. Application Data
`Provisional application No. 60/092,209, filed on Jul. 9,
`1998.
`
` ........................... F25D 23/00
`(51)
`.
`.
`220/592.09; 220/592.1;
`(52) U.S.Cl.
`220/592.2, 220/592.25
`(58) Field of Search ............................ 220/59209, 592.1,
`220/5922, 592.25, 592.26
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`........ 220/592.09
`2/1929 Fredenhagen
`
`3/1931 Klopsteg .................. 220/592.09
`
`1,701,323 *
`1,797,265 *
`
`Primary Examiner#aul T. Sewell
`Assistant Examiner—Troy Arnold
`(74) Attorney, Agent, or Firm—Kinney & Lange, PA.
`
`(57)
`
`ABSTRACT
`
`A container has a base, peripheral walls and a lid, Each of
`the base, peripheral walls and lid includes an interior wall
`spaced from an exterior wall, with vacuum panel in between.
`The sides of the vacuum panels are covered by compressible
`insulation fill, minimizing thermal flow along the vacuum
`panels despite any manufacturing tolerance differences in
`the width of the vacuum panels as compared to the distance
`between the interior wall and the exterior wall. The interior
`wall of the body of the container is provided by a liner
`formed of a single, deep drawn sheet of material. The
`exterior wall is similarly formed as a deep drawn shell. The
`inner liner and the outer shell are welded together with a
`head to encase the vacuum panels in a water-tight manner,
`with the liner, the shell the bead all formed of the same
`material.
`
`20 Claims, 4 Drawing Sheets
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`US. Patent
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`Jun.12,2001
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`US 6,244,458 B1
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`Jun. 12, 2001
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`US. Patent
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`Jun.12,2001
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`US 6,244,458 B1
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`US. Patent
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`Jun. 12, 2001
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`Sheet 4 0f4
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`US 6,244,458 B1
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`US 6,244,45 8 B1
`
`1
`THERMALLY INSULATED CONTAINER
`
`CROSS-REFERENCE TO RELATED
`
`APPLICATION(S)
`
`The present application claims priority from Provisional
`Application Serial No. 60/092,209,
`filed Jul. 9, 1998,
`entitled ACE CONTAINER.
`
`BACKGROUND OF THE INVENTION
`
`The present application relates to thermally insulated
`containers, and, more particularly,
`to thermally insulated
`containers which use vacuum panels as a primary mecha-
`nism to avoid thermal loss. Such thermally insulated con—
`tainers can be used for maintaining food, drink or medical
`items in a cold or frozen state without an outside energy or
`cooling source.
`Containers such as coolers have long been used to ther-
`mally insulate hot items or frozen or refrigerated items.
`Many items which are frozen or refrigerated are perisliables
`such as food items which must be maintained at a cold or
`frozen temperature to satisfactorily inhibit bacteria growth.
`The coolers typically contain walls made out of a thermally
`insulated material, such as a closed cell foam (for example,
`STYROFOAM) or other thermally insulating material. For
`repeated use in conjunction with food items,
`the thermal
`insulation layer is commonly housed in a more durable,
`sanitary housing structure, such as plastic, aluminum or
`stainless steel sheet material as layers on the inside and/or
`outside of the thermal insulation layer. Such coolers usually
`include a relatively flat base, generally vertical peripheral
`walls, and a removable lid which together form an enclo-
`sure. Each of the base wall, peripheral walls and lid may be
`thermally insulated.
`The coolers are generally wide-mouthed, with the lid
`being approximately the same size as the base, with the lid
`extending across the wide mouth. With the wide-mouthed
`construction, items placed in the cooler may be as large as
`the insulated chamber, because no neck is present to inter—
`fere with placement or removal of the items into or out of the
`cooler.
`
`In some instances the thermal insulation layer is provided
`by a vacuum between two spaced wall layers. For instance,
`vacuum insulated containers may come in the form of a
`circularly drawn vacuum bottle. Vacuum bottles are usually
`constructed with a small opening or neck, and are intended
`for holding liquid. Vacuum bottles are not commonly used to
`hold solid items such as perishable food items, because the
`neck is too small for the food items to pass.
`Vacuum insulation has also been available in a second
`form, as planar vacuum panels. A container constructed of
`planar vacuum panels would likely include six separate side
`walls joined to form a cubical or box shape, including twelve
`edges connected between the six sides of the vacuum panels.
`Such containers have a primary thermal dilliculty, referred to
`as “edge loss”, which must be overcome. In particular, While
`the panels themselves are very efficient thermal insulators,
`
`
`the edges between panels can contribute to thermal losses
`
`
`which are more significant than the thermal e iciency pro-
`vided by the panels themselves. Because of edge loss
`problems and cost of manufacture, vacuum panels have not
`gained widespread acceptance for use in container walls.
`It has also been long recognized that the thermal insula-
`tion provided by coolers may not always be sufficient to
`maintain the cold state of a product over a prolonged period
`of time. For this reason, various coolant materials have been
`
`2
`used in conjunction with the thermally insulated containers.
`The most basic and common coolant material is ice, which
`melts at 32° F. or 0° C. with a latent heat of fusion of
`approximately 80 cal/g, or approximately 333 kJ/kg. The
`melting phase change of the ice (i.e., the heat absorbed by
`the ice during melting) maintains the perishable goods near
`the melting temperature of ice.
`One shortcoming of ice is that the result of the phase
`change is water, and many of the frozen or refrigerated
`goods should be maintained in a dry state and not exposed
`to contact with water, Other coolant materials may be
`poisonous or have harmful effects if ingested, making it even
`more important that the coolant material does not contact a
`food item. For this reason, water and other water-based
`coolant materials have been enclosed in various coolant
`packets, such as rigid or semi-rigid plastic containers.
`Another shortcoming of ice is that ice melts at a temperature
`which is too high to maintain most food items in a frozen
`state. Thus, ice is a suitable coolant material for refrigerated
`goods, but not for frozen goods.
`Frozen carbon dioxide, or “dry ice”, is a commonly used
`coolant material for frozen goods. Dry ice has a higher latent
`heat, and a lower phase change temperature than water.
`Carbon dioxide undergoes a phase change from solid to gas
`at approximately —78.5° C. or —llO° F., with a latent heat of
`sublimation of about 573 kJ/kg. Skin contact to dry ice is
`somewhat hazardous, and dry ice should generally be
`handled without skin contact.
`
`the various
`Regardless of the use of coolant materials,
`shortcomings of suitable thermally insulative containers
`have limited their use in many potential applications. Addi—
`tional mechanical or thermal means of cooling (i.e., freezers,
`refrigerated trucks and box cars, etc.), at a significant
`expense, are often required for handling of frozen items.
`Additional methods are needed for the handling of frozen
`items in a warm or ambient for periods of time ranging from
`several minutes to hours to several days.
`BRIEF SUMMARY OF THE INVENTION
`
`invention involves a thermally insulated
`The present
`container including vacuum panels positioned between an
`interior liner and an exterior shell. One or more sides of the
`vacuum panels are covered by compressible thermal
`insulation, i.e., between the vacuum panels and the interior
`liner and/or exterior shell. The compressible thermal insu-
`lation layer limits thermal flow along the walls, which in
`turn decreases the edge losses due to thermal flow into/out
`of the container between vacuum panels, In one aspect, the
`liner and the shell are welded together with a bead to encase
`the vacuum panel in a water-tight manner, with the liner, the
`shell and the bead all formed of the same material.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`10
`
`tom
`
`30
`
`L»LA
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`40
`
`50
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`FIG. 1 is a perspective View of the container of the present
`invention with the lid open.
`FIG. 2 is a cross sectional vier of a side wall of the
`container of FIG. 1 with the lid closed.
`
`60
`
`FIG. 3 is an exploded cross sectional View of FIG. 2
`showing assembly of the container of FIG. 1.
`FIG. 4 is an enlarged portion of FIG. 2 showing a cross
`sectional View of a bottom corner of the container of FIG. 1.
`
`FIG. 5 is a plan view of a coolant material pouch for use
`in the container of FIG. 1.
`
`While the above—identified drawing figures set forth a
`preferred embodiment, other embodiments of the present
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`US 6,244,45 8 B1
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`3
`invention are also contemplated, some of which are noted in
`the discussion. In all cases,
`this disclosure presents the
`illustrated embodiments of the present invention by way of
`representation and not
`limitation. Numerous other minor
`modifications and embodiments can be devised by those
`skilled in the art which fall within the scope and spirit of the
`principles of this invention.
`DETAILED DESCRIPTION
`
`A container 10 as shown in FIG. 1 generally includes a
`body 12 having a bottom wall or base 16, peripheral side
`walls 14 extending upward from the base 16 to form an
`enclosure with an opening, and a top wall or lid 18. The base
`16,
`the side walls 14 and the lid 18 are all
`thermally
`insulated, and a substantial thickness is required to provide
`the desired degree of insulation and rigidity. For instance,
`the base 16, the side walls 14 and the lid 18 may each be 1
`or 2 inches thick. The size of the container 10 may be
`selected according to its desired use. In one embodiment, the
`enclosure is about 2300 cubic inches.
`
`All of the side walls 14 of the preferred embodiment are
`rectangular to produce a container 10 having a box-like
`shape, but other shapes could alternatively be used.
`However,
`the rectangular box like shape of the present
`invention is particularly beneficial for stacking of multiple
`containers 10 side—by—side and one atop another.
`The body 12 of the container 10 includes an inner liner 20
`on its interior side and an outer shell 22 on its exterior, with
`thermal insulation 24 (described in detail below with refer-
`ence to FIGS. 2—4) in the space between the inner liner 20
`and the outer shell 22. The inner liner 20 includes a lip 26
`which extends outward over the thickness of the thermal
`insulation 24 in the side walls 14. For instance, the lip 26
`may extend about 1 or 2 inches outward. The lip 26 mates
`against the lid 18, and in the preferred embodiment the lip
`26 provides a horizontal, flat surface. The inner liner 20
`terminates at an edge 30 which preferably turns downward
`from the lip 26. For instance,
`the edge 30 may extend
`downward such as a quarter of an inch from the lip 26. The
`edge 30 is used to secure the inner liner 20 and the outer
`shell 22, By having the edge 30 extend downward, the edge
`30 between the inner liner 20 and the outer shell 22 is
`removed slightly from the junction between the body 12 of
`the container 10 and the lid 18.
`
`Slight ridges or indentations 32 may be formed into one
`or both of the outer shell 22 and the inner liner 20. These
`indentations 32 assist in increasing rigidity of the inner liner
`20 and outer shell 22, reducing the potential for buckling or
`unwanted deformation of the inner liner 20 and outer shell
`22 during use of the container 10.
`The inner liner 20 is preferably integrally formed from a
`single piece of material. For instance, the inner liner 20 may
`be deep drawn from a flat sheet of thermoplastic material. If
`the inner liner 20 and the lip 26 are separate pieces, the lip
`26 may be made of thermoplastic material, and the remain-
`der of the inner liner 20 may be made of metal. By being
`integrally formed, the inner liner 20 provides an interior side
`of both the base 16 and the side walls 14, without any
`thermal discontinuity in the inner liner 20 between the base
`16 and the side walls 14. Similarly, the outer shell 22 is
`preferably integrally formed from a single piece of material
`to provide no thermal discontinuity in the outer shell 22
`between the base 16 and the side walls 14.
`
`The inner liner 20 and the outer shell 22 may have a slight
`draft to assist in the deep drawing formation process, such
`as a draft on the order of a few percent. The draft on the inner
`
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`liner 20 is preferably the same as the draft on the outer shell
`22, so the inner liner 20 of each side wall 14 is parallel to
`its outer shell 22. This allows a generally uniform thickness
`to the thermal insulation 24 in the side walls 14.
`The inner liner 20 has a wall thickness sufficient for
`substantial rigidity, although some limited deformation flex—
`ibility is preferred. The wall thickness of the inner liner 20
`allows it
`to withstand significant wear and tear without
`permanent deformation. For instance, the inner liner 20 may
`have a wall thickness of about 0.05 to 0.25 inches, depend-
`ing upon material. This thickness should be minimized,
`particularly at the lip 26, so as to minimize the amount of
`thermal conduction which occurs along the inner liner 20
`particularly as contributing to edge loss. The outer shell 22
`is preferably thicker and stronger than the inner liner 20, as
`the outer shell 22 may undergo substantia abuse during use.
`A thicker outer shell 22 provides for a more rugged container
`10 during handling (or mishandling) of the container 10. For
`instance, in a preferred embodiment, the inner liner 20 may
`have a wall thickness of 1/15 of an inch, waile the outer shell
`22 may have a wall thickness of about 1/2; of an inch.
`The outer shell 22 and the inner liner 20 should be joined
`at the edge 30 forming a water—tight seal. In the preferred
`embodiment, the water-tight seal is provie ed by a bead weld
`36 of material which is thermally welded at the edge 30. By
`having a water tight seal, humidity or moisture build—up in
`the side walls 14 is prevented. Dryness Jetween the outer
`shell 22 and the inner liner 20 maintains the full thermal
`insulation benefits of the container 10, as well as minimizing
`weight and minimizing the potential for Jacterial growth.
`The material of the container 10, and particularly the
`material of the inner liner 20 which may be in contact with
`a coolant material (not shown), should not become brittle
`even at very cold temperatures. In this way, the inner liner
`20 will not crack or shatter if the container 10 is dropped
`during use.
`The outer shell 22 and the inner liner 20 are preferably
`
`formed of the same material, or by materials having similar
`
`
`
`coe icients of thermal expansion. If a bead weld 36 is used
`to seal the outer shell 22 and the inner liner 20 together, the
`bead weld 36 should also be formed of the same material or
`a material having the same melt temperature. The difference
`between ambient conditions and the container interior may
`be 100° F. or more. While the inner liner 20 maintains a
`fairly steady temperature profile during use of the container
`10, the temperature differential of cycling from storage to
`steady state use is significant. By having the outer shell 22,
`the inner liner 20 and the bead weld 36 (if present), formed
`of the same material, thermal cycling of the container 10
`does not create thermal expansion induced stress at the bead
`weld 36 or other sealed joint between the inner liner 20 and
`the outer shell 22. The lack of thermal expansion induced
`stress at the bead weld 36 increases longevity of the water-
`tight seal provided by the bead weld 36.
`I.ocating the bead weld 36 outside the junction 40
`between the side walls 14 and the lid 18 provides several
`advantages. First, this location will stay near ambient tem-
`perature during use of the container 10, thus minimizing
`thermal cycling at the bead weld 36. Second, any uneven—
`ness in the bead weld 36 will not form part of the junction
`40 between the lid 18 and the body 12 of the container 10,
`so the junction 40 between the lid 18 and the body 12 can
`be as even as possible. Third, the bead weld 36 is typically
`of greater thickness than the inner liner 20 and lip 26, and
`thus thermal conduction occurs faster at the bead weld 36
`than along the inner liner 20. Locating the bead weld 36
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`US 6,244,45 8 B1
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`5
`outside the junction 40 between the side walls 14 and the lid
`18 keeps this increase thermal conduction from significantly
`contributing to edge loss.
`The inner liner 20 and the outer shell 22 may be formed
`
`of metal such as stainless steel, but are more preferably
`
`
`
`formed of a thermoplastic material having a lower coe i—
`cient of thermal conduction than metals. A low coellicient of
`thermal conduction is particularly important along the lip 26
`(where the material extends outward from the enclosure). If
`a metal inner liner is used,
`the lip 26 should be formed
`separate from the remainder of the inner liner 20 and of a
`non—metal material. Preferred thermoplastic materials
`include polycarbonate, polystyrene and glass-filled nylon,
`with the most preferred material being high density poly-
`ethylene (“HDPE”).
`llandles 42 may be provided along the outside of the
`container 10. In the preferred embodiment, three handles 42
`are provided, one on each unhinged side wall 14. The
`preferred handles 42 hinge outward to an extended position
`for lifting and inward to a position parallel with the side
`walls 14 to minimize the possibility of damage and to
`minimize the space necessary for container storage.
`The lid 18 for the container 10 may be formed similarly
`to the body 12 of the container 10, including a lid liner 44
`and a lid shell 46 with thermal insulation 24 between the lid
`liner 44 and lid shell 46. The preferred container 10 includes
`a lid liner 44 which is drawn from high density polyethylene
`with a material thickness of about 1/15 inch, and a lid shell 46
`which is drawn from high density polyethylene with a
`material
`thickness of about
`1/3
`inch. The lid liner 44 is
`attached to the lid shell 46 with a high density polyethylene
`bead weld 36 that provides a water-tight se al, The bead weld
`36 is located just outside the junction 40 between the lid 18
`and the body 12 of the container 10.
`The lid liner 44 preferably includes a darn 48, sized to be
`received in the enclosure of the inner liner 20. The dam 48
`extends a substantial distance downward into the enclosure.
`For instance, the darn 48 may extend approximately 11/2 inch
`downward into the enclosure. The dam 48 and the inner liner
`20 have a slight flexibility, and a slight
`interference fit
`between the dam 48 and the inner liner 20 allows for a snug
`(but not pressure-tight) seal between the dam 48 and the
`inner liner 20. The dam 48 is thermally insulative and helps
`to minimize thermal loss through the junction 40 between
`the lid 18 and the body 12 of the container 10.
`
`To the outside of the dam 48, a gasket 50 is provided to
`
`
`increase the thermal insulation e iciency at the junction 40
`between the lid 18 and the body 12 of the container 10. The
`gasket 50 is preferably formed in a tubular shape so as to
`provide maximum compressibili y. The gasket 50 maybe
`formed for example from ethylene—propylene—diene mono—
`mer (“EPDM”) with an adhesive back, allowing for adhe-
`sive attachment of the gasket 50 to the lid 18.
`The preferred gasket 50 is not continuous, but rather
`includes a pressure release separation 52. The pressure
`release separation 52 may be simply provided by aligning
`and abutting (but notjoining) ends of the gasket 50 together.
`
`The pressure release separation 52 provides an outlet for
`
`
`
`gases within the container 10 if the pressure di erential
`between the container 10 and atmosphere exceeds a desired
`maximum value. In particular, the container [0 is intended
`to be used with a coolant material 38 which expands
`volumetrically such as when dry ice evaporates into carbon
`
`
`dioxide. The gasket 50 prevents any non-pressurizec airflow
`
`
`into or out of the container 10, but a pressure di erential
`such as 0.1 or 0.2 atmospheres will cause the gasket 50 to
`
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`slightly open at the pressure release separation 52 to allow
`carbon dioxide to escape from the container 10.
`The pressure release separation 52 permits pressure
`release both into as well as out of the container 10. For
`instance, when transported by airplane, the cargo compart-
`ment of the airplane may depressurize during the flight.
`Because of the pressure release separation 52, the enclosure
`will similarly depressurize. If pressure is not permitted back
`into the container 10, the lid 18 may be impossible to remove
`from the body 12 of the container 10. The pressure release
`separation 52 allows substantial repressurization of the
`container 10 when the cargo compartment of the airplane
`repressurizes.
`If desired, the lid 18 may be entirely separable from the
`body 12 of the container 10. However, the preferred lid 18
`is hinged to the body 12 of the container 10. llor instance, the
`lid shell 46 may be attached to the outer shell 22 of the
`container 10 with two spaced hinges 54.
`A lanyard 56 may be used to prevent the lid 18 from
`pivoting too far open on the hinge and to allow the lid 18 to
`rest in an upward, open position without tipping of the
`container 10. The lanyard 56 is attached at one end to the
`inner liner 20 and at the other end to the lid liner 44. The
`lanyard 56 may be for instance a vinyl coated flexible wire
`cable. The attachment of the lanyard 56 to the inner liner 20
`should be at depth greater than the dam 48 so that the lanyard
`56 does not interfere with the mating of the dam 48 into
`inner liner 20 when the container 10 is closed. Latches 58
`may be provided for securing the lid 18 in a closed position.
`Straps 60 may be attached to the lid shell 46 and the outer
`shell 22 so the container 10 may be easily locked such as
`with a tamper-evident lock (not shown).
`As mentioned previously, the inner liner 20 and the outer
`shell 22 should provide a watertight seal for the thermal
`insulation 24. To this end, the handles 42, hinges 54, lanyard
`56, latches 58 and straps 60 should be secured to the shells
`22,46 with a water-tight attachment. For example, adhesive
`attachments or welded attachments may be used. In the
`preferred embodiment, closed end rivets and/or threaded
`fasteners are screwed into threaded metal backing plates
`with insert weld nuts are used in attaching components to the
`shells 22,46 in a sealed manner.
`As shown in FIGS. 2—4, vacuum panels 62 are used to
`provide the primary thermal insulation between the inner
`liner 20 and outer shell 22. In the base 16, the side walls 14
`and the lid 18, the thickness of the vacuum panels 62 is
`selected to roughly match the space between the outer shell
`22 and the inner liner 20. For instance, the vacuum panels 62
`may nominally be one or two inches thick.
`Each vacuum panel 62 consists of a permeable medium
`(foam or powder) filler 64, encapsulated with a film laminate
`barrier material 66, which has been sealed and evacuated
`below atmospheric pressure. In its evacuated state, a flexible
`barrier film 66 is sealed around the porous medium 64. The
`barrier film 66 retains the evacuated condition for the life of
`the vacuum panel 62. To render the container 10 more
`portable, the porous medium 64 should be lightweight. One
`preferred porous medium 64 is rigid polystyrene foam
`available from Dow Chemical Co. of Midland, Mich. as
`INSTILL foam. Other permeable media include silica, fiber-
`glass and urethane. For high performance vacuum panels 62,
`the panels may be evacuated to about 5 Torr or less. In the
`preferred embodiment, the vacuum panels may be evacuated
`to between 1.0 and 0.001 Torr. The barrier film 66 must be
`able to hold the low vacuum pressure for a prolonged period
`of time, and may be a multiple layer hermetic film. Suitable
`
`PGR2021-00085
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`Pelican EX1018 Page 8
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`PGR2021-00085
`Pelican EX1018 Page 8
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`US 6,244,45 8 B1
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`7
`high performance barrier film to retain this low vacuum
`pressure is available from E.I. duPont de Nemours & Co. of
`Wilmington, Del. The vacuum panels 62 provide very
`efficient thermal insulation, typically on the order of about
`four times the insulation efficiency provided by traditional
`thermal insulation materials.
`
`To form the vacuum panels 62 at low cost, the barrier film
`66 is not molded to fit around the porous medium 64 but
`rather is provided as sheet material with edges 72 sealed
`together. Because a tight seal is critical, the edges 72 of the
`barrier film 66 may be joined together over a sealed portion
`which extends for 1/2 inch or more and at an angle to the
`underlying surface of the porous medium 64. In part because
`of the sealed portions 72 of the barrier film 66, the vacuum
`panels 62 do not have a smooth, uniform outer profile.
`Accordingly, adjacent vacuum panels 62 cannot be generally
`positioned without space between them. This space can lead
`to significant edge losses in thermal efficiency.
`In one aspect of the present invention, the vacuum panels
`62 are not the sole insulation between the inner liner 20 and
`the outer shell 22. Edges 72 of the vacuum panels 62 are
`covered with a compressible layer of thermal insulation,
`which in the preferred embodiment includes flexible sheet
`insulation 76 and loft material 74. The compressible layer of
`thermal insulation 74,76 also extends over the planar side
`surfaces 70 of the vacuum panels 62,
`i.e., between the
`vacuum panels 62 and the inner liner 20 and outer shell 22.
`The compressible layer of thermal insulation 74,76 may be
`placed between the vacuum panel 62 and the inner liner 20
`or between the vacuum panel 62 and the outer shell 22. In
`the preferred embodiment, each side surface of each vacuum
`panel 62 is covered with a compressible layer of thermal
`insulation 74,76, so no vacuum panel 62 contacts either the
`inner liner 20 or the outer shell 22.
`
`For example, the compressible layer of thermal insulation
`may be provided by about an J/s inch thick layer 76 of
`flexible open cell urethane foam. As best illustrated in FIG.
`3, the insulation layer 76 is preferably wrapped around each
`of the vacuum panels 62. To prevent the insulation layer 76
`from becoming dislodged when the vacuum panels 62 are
`positioned between the inner liner 20 and the outer shell 22,
`the compressible insulation layer 76 may be taped around
`the vacuum panels 62.
`The compressible insulation layer may also be provided
`by a loft material 74 having a significant loft. In the preferred
`embodiment,
`the loft material 74 is a non-woven web
`comprised of 5.5 denier polyester fiber with a silicone finish
`and no binder. Either the loft material 74 or the flexible sheet
`insulation 76 may be used by itself to provide the desired
`compressible insulation layer 74,76. However, in the pre-
`ferred embodiment loft material 74 is used in conjunction
`with the flexible sheet insulation 76. In particular, a blanket
`of loft material 74 is positioned over the vacuum panel 62
`for the base 16, extending under the vacuum panels 62 for
`the side walls 14.
`
`The container 10 of the present invention provides ther—
`mal elliciency not previously attainable. The believed
`mechanism for the increase in thermal efficiency is further
`described with reference to FIG. 4. FIG. 4 includes arrows
`indicating thermal flow associated with the container 10 of
`the present invention. While the container 10 described
`herein is intended primarily for maintaining cold items, the
`present invention is equally applicable to maintaining items
`within the container 10 at an elevated temperature above
`ambient. The thermal flow depicted in FIG. 4 can thus be the
`flow of heat or the flow of cold.
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`10
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`tom
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`Arrows A indicate the thermal flow through the vacuum
`panels 62. Because the vacuum panels 62 provide very
`efficient thermal insulation, thermal floonutward through
`the vacuum panels 62 is minimal. Edge loss associated with
`thermal flow outward between adjacent vacuum panels 62 is
`illustrated with arrows B. Adjacent vacuum panels 62 cannot
`be spaced closely enough to eliminate edge loss B, particu—
`larly with the spacing between vacuum panels 62 caused by
`the sealed edges 72 of the barrier film 66. The presence of
`the compressible insulation layer 72 in the space between
`vacuum panels 62, including both the flexible sheet 76 and
`the loft material 74, significantly reduces edge loss B. Even
`with this reduction, edge loss B likely dominates over
`thermal loss A through the vacuum panels 62.
`Arrows C indicate thermal flow along the vacuum panels
`62 between the vacuum panels 62 and the inner liner 20.
`Arrows D indicate thermal flow along the vacuum panels 62
`between the vacuum panels 62 and the outer shell 22. The
`compressible insulation layer 74,76 running along the side
`surfaces 70 of the vacuum panels 62 significantly reduces
`thermal flows C and D. Thermal flows C and D run around
`the cold source within the container 10, rather than toward
`or away from it. Nonetheless, thermal flows C and D are
`believed significant in the overall thermal efficiency of the
`container 10, because thermal flows C and D contribute to
`the edge loss B. The compressible insulation layer 74,76
`disposed along the side surfaces 70 of the vacuum panels 62
`provides a reproducible, consistent reduction of thermal
`flows C and D. To provide the maximum benefit,
`the
`compressible insulation layer 74,76 should extend along
`substantially all of the side surface of the vacuum panel 62.
`The reduction of thermal flows C and D helps to minimize
`edge loss B, and increases the overall thermal efficiency of
`the container 10.
`insulation 74 in the base 16
`Positioning of the loft
`immediately under the inner liner 20 is particularly advan-
`tageous. In manufacture of the container 10, the distance
`between the outer shell 22 and the inner liner 20 in the base
`16 is subject to considerable manufacturing tolerance. The
`thickness of the vacuum panel 62 disposed in the base 16
`also has manufacturing tolerance, albeit much smaller. In
`use of the container 10, the distance between the outer shell
`22 and the inner liner 20 in the base is subject to consider-
`able stress and variance due to temperature differences
`between the inside and the outside of container 10, weight
`of objects placed inside the container 10, weight placed on
`the container 10, or impacts sustained by the outer or inner
`surfaces. By contrast,
`the variance experienced by the
`vacuum panel 62 disposed in the base 16 is relatively less.
`The loft of the non—woven loft material 74 compensates for
`both manufacturing tolerance and movement or deformation
`of the inner liner 20 relative to the outer shell 22.
`
`The flexible sheet insulation 76 also provides durability
`and protection to the barrier film 66 material of the vacuum
`panels 62, minimizing the potential for puncture and/or
`wear. To further protect against puncture and/or