U.S. patent application number 11/277078 was filed with the patent office on 2006-08-31 for apparatus and methods for warming and cooling bodies.
This patent application is currently assigned to Coolhead Technologies, Inc.. Invention is credited to Katie Man-Ki Au, Yunquan Chen, Christopher Lawrence Clarke, John Robert Fletcher, R. David FLETCHER.
Application Number | 20060191675 11/277078 |
Document ID | / |
Family ID | 36930999 |
Filed Date | 2006-08-31 |
United States Patent
Application |
20060191675 |
Kind Code |
A1 |
FLETCHER; R. David ; et
al. |
August 31, 2006 |
APPARATUS AND METHODS FOR WARMING AND COOLING BODIES
Abstract
A flexible heat exchanger is suitable for heating or cooling
living subjects or objects. The heat exchanger has a volume having
at least one inlet for receiving a heat exchange fluid and at least
one outlet. A flexible heat exchange plate that is essentially
impermeable to the heat exchange fluid is penetrated by
substantially rigid thermally-conductive members. The members
provide paths of high thermal conductivity through the plate. The
heat exchange fluid may be water.
Inventors: |
FLETCHER; R. David; (Surrey,
CA) ; Fletcher; John Robert; (Surrey, CA) ;
Au; Katie Man-Ki; (Richmond, CA) ; Clarke;
Christopher Lawrence; (Vancouver, CA) ; Chen;
Yunquan; (Delta, CA) |
Correspondence
Address: |
OYEN, WIGGS, GREEN & MUTALA LLP;480 - THE STATION
601 WEST CORDOVA STREET
VANCOUVER
BC
V6B 1G1
CA
|
Assignee: |
Coolhead Technologies, Inc.
Delta
CA
|
Family ID: |
36930999 |
Appl. No.: |
11/277078 |
Filed: |
March 21, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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PCT/CA04/01660 |
Sep 22, 2004 |
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11277078 |
Mar 21, 2006 |
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10665073 |
Sep 22, 2003 |
7077858 |
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PCT/CA04/01660 |
Sep 22, 2004 |
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10665074 |
Sep 22, 2003 |
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PCT/CA04/01660 |
Sep 22, 2004 |
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60663267 |
Mar 21, 2005 |
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60565537 |
Apr 27, 2004 |
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60565517 |
Apr 27, 2004 |
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60580356 |
Jun 18, 2004 |
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Current U.S.
Class: |
165/172 |
Current CPC
Class: |
F28F 3/12 20130101; F28F
3/022 20130101 |
Class at
Publication: |
165/172 |
International
Class: |
F28F 1/10 20060101
F28F001/10 |
Claims
1. A flexible heat exchanger comprising: a volume having at least
one inlet for receiving a heat exchange fluid and at least one
outlet; and, a flexible front sheet essentially impermeable to the
heat exchange fluid, the front sheet carrying a plurality of
substantially-rigid members, each of the members comprising an
exposed thermally-conductive surface on a thermally-conductive
first body on an outside of the front sheet and having a
thermally-conductive portion extending from the
thermally-conductive first body, through the front sheet, and into
the volume, each of the plurality of members comprising opposed
gripping surfaces held firmly against opposed sides of the front
sheet.
2. A flexible heat exchanger according to claim 1 wherein the
volume is defined between the front sheet and a flexible rear
sheet.
3. A flexible heat exchanger according to claim 2 wherein the rear
sheet is shaped to provide indentations at locations that are
adjacent to the substantially-rigid members and the
thermally-conductive portions of the substantially-rigid members
project into the indentations.
4. A flexible heat exchanger according to claim 3 wherein wherein
the members are arranged in rows to provide a plurality of
substantially unbroken lines of the front sheet extending between
the rows of the members.
5. A flexible heat exchanger according to claim 1 wherein wherein
the members are arranged in rows to provide a plurality of
substantially unbroken lines of the front sheet extending between
the rows of the members.
6. A flexible heat exchanger according to claim 4 wherein the
members are arranged in an array such that the plurality of
substantially unbroken lines of the front sheet includes first and
second sets each comprising a plurality of the unbroken lines
wherein the unbroken lines of the first set intersect with the
unbroken lines of the second set.
7. A flexible heat exchanger according to claim 1 having drape.
8. A flexible heat exchanger according to claim 1 wherein the
volume comprises a channel extending from the inlet to the outlet
wherein a cross-section of the channel varies periodically along a
length of the channel.
9. A flexible heat exchanger according to claim 8 wherein the
thermally-conductive members are spaced apart along the channel and
the channel includes constricted areas located between the
thermally-conductive members.
10. A flexible heat exchanger according to claim 8 wherein the
channel is a sinuous channel.
11. A flexible heat exchanger according to claim 1 wherein the
thermally-conductive surface of the first body is spaced outwardly
from the outside of the front sheet.
12. A flexible heat exchanger according to claim 1 wherein an area
of the thermally-conductive surface of the first bodies exceeds a
total cross sectional area of the thermally-conductive portions
measured where the thermally-conductive portions pass through the
front sheet.
13. A flexible heat exchanger according to claim 1 wherein the
thermally-conductive portions project into the volume past an
inside face of the front sheet by distances of at least 3 mm.
14. A flexible heat exchanger according to claim 1 wherein the
thermally-conductive portions each have a thermal conductivity of
at least 50 Wm.sup.-1K.sup.-1.
15. A flexible heat exchanger according to claim 1 wherein the
thermally-conductive portions each have a thermal conductivity of
at least 100 Wm.sup.-1K.sup.-1.
16. A flexible heat exchanger according to claim 1 wherein the
thermally-conductive portions are made of metal.
17. A flexible heat exchanger according to claim 16 wherein the
thermally-conductive portions are made of metals selected from the
group consisting of: aluminum, copper, gold, silver, alloys of two
or more of aluminum, copper, gold, or silver with one another and
alloys of one or more of aluminum, copper, gold, or silver with one
or more other metals.
18. A flexible heat exchanger according to claim 1 wherein the
outside of the front sheet is faced with an absorbent fabric and
the thermally-conductive portions of the members project through
the absorbent fabric.
19. A flexible heat exchanger according to claim 1 wherein the
plurality of the members covers at least 30% of an area of the
outside of the front sheet.
20. A flexible heat exchanger according to claim 2 wherein the
front and rear sheets are attached to one another in a pattern of
attached areas to provide a sinuous channel in the volume, the
sinuous channel and extending between the inlet and outlet.
21. A flexible heat exchanger according to claim 20 wherein the
members are spaced apart along the channel, each of the members is
located in a wider portion of the channel and the channel has a
plurality of narrower portions spaced apart along the channel, the
narrower portions each located between an upstream one of the
members and a downstream one of the members.
22. A flexible heat exchanger according to claim 1 wherein, for
each of the plurality of members, the sheet is received in a groove
extending circumferentially around the member.
23. A flexible heat exchanger according to claim 1 wherein each of
the plurality of members comprises a rivet having a head on the
outside of the front sheet and a washer on an inside of the front
sheet, the thermally-conductive body comprises a head of the rivet
and the front sheet is gripped between the head of the rivet and
the washer.
24. A flexible heat exchanger according to claim 1 wherein the
thermally-conducting surface is either flush with or projects
outwardly from an outside surface of the wall.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of PCT patent
application No. PCT/CA2004/001660 filed on 22 Sep. 2004 which is a
continuation-in-part of U.S. application Ser. No. 10/665,073 filed
on 22 Sep., 2003 and entitled FLEXIBLE HEAT EXCHANGERS FOR MEDICAL
COOLING AND WARMING APPLICATIONS, Ser. No. 10/665,074 filed on 22
Sep., 2003 and entitled FLEXIBLE HEAT EXCHANGERS pursuant to 35
U.S.C. .sctn. 120. PCT patent application No. PCT/CA2004/001660
also claims the benefit of U.S. patent application 60/565,517 filed
on 27 Apr. 2004 and entitled FLEXIBLE HEAT EXCHANGERS, 60/565,537
filed on 27 Apr. 2004 and entitled FLEXIBLE HEAT EXCHANGERS FOR
MEDICAL COOLING AND WARMING APPLICATIONS, and 60/580,356 filed on
18 Jun. 2004 and entitled METHOD AND APPARATUS FOR AFFIXING THROUGH
MEMBER IN MEMBRANE, all of which are hereby incorporated by
reference herein. This application claims the benefit of U.S.
application No. 60/663,267 filed on 21 Mar. 2005 pursuant to 35
U.S.C. .sctn. 119.
TECHNICAL FIELD
[0002] The invention relates to heat exchangers. The invention has
particular application to heat exchangers for use in warming or
cooling living subjects. The invention may be applied to cooling
the brains or other body parts of living subjects. The apparatus
and methods generally provide a heat exchange fluid, which is a
liquid in some embodiments and a gas in other embodiments, that
passes through a heat exchanger to exchange heat with a body to be
warmed or cooled.
BACKGROUND
[0003] It has been discovered that quickly inducing hypothermia can
significantly improve the recovery prospects of patients who suffer
global ischemic brain injury secondary to cardiac arrest and
probably focal ischemic brain injury from thrombotic or embolic
causes. The latter is referred to as an ischemic stroke. Some
trials have placed global and focal ischemic brain damaged victims
in whole-body cooling chambers or devices. Intra vascular devices
are used for whole body cooling and, secondarily, brain cooling.
Such chambers or devices are unwieldy and can be intimidating for
the patient. Fletcher, U.S. Pat. No. 6,511,502 discloses methods
for cooling a subject's brain by applying heat exchangers to the
neck of the subject adjacent the subject's carotid arteries. The
heat exchangers cool blood flowing to the subject's brain.
[0004] In various other areas of medicine it is desirable to cool
or warm body parts. For example, U.S. Pat. Nos. 4,138,743;
5,916,242; 4,566,455; 4,750,493; 4,763,866; 4,020,963; 5,190,032;
5,486,204; 5,643,336; 5,897,581; 5,913,855; 5,057,964; and
6,030,412 relate to cooling or warming body.
[0005] Various types of heat exchanger exist. Air cooled heat sinks
are structures which take heat from an object and dissipate the
heat into ambient air. Such heat sinks typically consist of a
finned piece of thermally-conductive material having a face which
can be placed in thermal contact with an object, such as an
electronic component, to be cooled. Some heat sinks are equipped
with fans located to flow air past the fins to improve the rate at
which heat is dissipated.
[0006] U.S. Pat. No. 6,549,411 B1 discloses a flexible heat sink
that can be attached to a generally flat surface of an object. The
heat sink can flex to conform to the surface of the object to
achieve improved contact with the object, and hence increase the
efficiency of heat transfer between the heat sink and the object.
U.S. Pat. No. 6,367,541 B2 discloses a heat sink that can be
attached to multiple electronic chips which have different heights.
The heat sink dissipates heat from the chips into ambient air. The
devices disclosed in these patents are not suitable for heating or
cooling living subjects.
[0007] U.S. Pat. No. 5,368,093 discloses a flexible bag filled with
thermal transfer fluid useful for thawing frozen foods. U.S. Pat.
No. 4,910,978 discloses a flexible pack containing a gel. The pack
can be cooled and applied to a patient for cold therapy. The pack
conforms to surface contours of the patient's body. These devices
have limited cooling capacities.
[0008] More sophisticated heat exchangers use a heat exchange fluid
such as a cooling or heating liquid instead of ambient air to carry
heat away from or provide heat to an object to be cooled or heated.
Golden, U.S. Pat. No. 4,864,176 discloses a thermal bandage. The
bandage includes a conforming member adapted to be placed against
the skin. A thermal pack includes a chamber through which fluid can
be circulated. The thermal pack is separated from the conforming
member by a thermally-conductive surface. U.S. Pat. No. 5,757,615
discloses a flexible heat exchanger with circulating water as
coolant for cooling a notebook computer. U.S. Pat. No. 5,643,336
discloses a flexible heating or cooling pad with circulating fluid
for therapeutically treating the orbital, frontal, nasal and
peri-oral regions of a patient's head. U.S. Pat. No. 6,551,347 B1
discloses a flexible heat exchange structure having
fluid-conducting channels formed between two layers of flexible
material for heat/cold and pressure therapy. U.S. Pat. Nos.
6,197,045 B1 and 6,375,674 B1 disclose a flexible medical pad with
an adhesive surface for adhering the pad to the skin of a patient.
U.S. Pat. No. 6,030,412 discloses a flexible enveloping member for
enveloping a head, neck, and upper back of a mammal for cooling the
brain of the mammal suffering a brain injury. All of these heat
exchangers require heat to pass through a layer of some flexible
material such as rubber, a thermoplastic, or a flexible plastic
such as polyurethane. In addition, heat is exchanged between the
surface of the flexible material and circulating fluid. Water is
the most commonly used circulating fluid.
[0009] Rubber and flexible plastics are poor conductors of heat. To
provide a high heat transfer efficiency in a flexible heat
exchanger in which heat is transferred across a layer of rubber or
plastic the layer must be very thin. This makes such heat
exchangers prone to damage. In addition, water is a poor heat
conductor. Heat exchange between the flexible material and water is
largely dependent on convection. Water flowing over a relatively
flat surface will often not result in efficient heat exchange.
[0010] U.S. Pat. No. 3,825,063 discloses a heat exchanger having
metal screens of fine mesh with internal plastic barriers that at
least partly penetrate the screens. The screens are stacked to
provide transverse heat conduction relative to longitudinal flow
paths. U.S. Pat. No. 4,403,653 discloses a heat transfer panel
comprising a woven wire mesh core embedded in a layer of plastic
material. The mesh and closure layer extend in the same
longitudinal direction. U.S. Pat. No. 5,660,917 discloses a sheet
with electrically insulating thermal conductors embedded in it. The
apparatus disclosed in those patents is not adapted for warming or
cooling living subjects.
[0011] There remains a need for heat exchangers suitable for
warming or cooling living subjects via the surface of the subjects'
skin. There is a particular need for such heat exchangers that
provide a high ratio of heat-transfer capacity to skin contact
area. There is also a need for heat exchangers which can be used in
practising the methods described in Fletcher, U.S. Pat. No.
6,511,502 and which avoid at least some disadvantages of prior heat
exchangers. In some fields there remains a need for heat exchangers
capable of providing high heat transfer rates between the heat
exchangers and objects that are not flat, are vibrating or are
otherwise difficult to interface to. There is a particular need for
such heat exchangers which have high ratio of heat-transfer
capacity to contact area.
SUMMARY OF THE INVENTION
[0012] The invention relates to heat exchangers and has many
aspects which may be combined or, in some cases, exploited
individually. One aspect of the invention provides a flexible heat
exchanger comprising a volume having at least one inlet for
receiving a heat exchange fluid and at least one outlet and a
flexible sheet essentially impermeable to the heat exchange fluid.
The sheet carries a plurality of substantially-rigid members. Each
of the members comprises an exposed thermally-conductive surface on
a thermally-conductive first body on an outside of the sheet and
having a thermally-conductive portion extending from the
thermally-conductive first body, through the sheet, and into the
volume. Each of the plurality of members comprising opposed
gripping surfaces held firmly against opposed sides of the
sheet.
[0013] Another aspect of the invention provides a flexible heat
exchanger comprising a volume having at least one inlet for
receiving a heat exchange fluid and at least one outlet. The volume
has a flexible wall essentially impermeable to the heat exchange
fluid. The wall carries a plurality of substantially-rigid members.
Each of the members comprising a thermally-conductive surface on an
outside of the wall and has a thermally-conductive portion
extending from the thermally-conductive surface, through the wall
and into the volume. The thermally-conducting surface is supported
at a location spaced outwardly apart from an outside surface of the
wall.
[0014] Another aspect of the invention provides a flexible heat
exchange surface for use in a heat exchanger. The flexible heat
exchange surface comprises a flexible sheet essentially impermeable
to the heat exchange fluid. The sheet carries a plurality of
substantially-rigid members sealed to the sheet. Each of the
members comprises first and second thermally-conductive bodies
exposed on first and second sides of the sheet. The first and
second thermally-conductive bodies are connected by a narrowed
thermally-conductive portion having a cross sectional area smaller
than a cross sectional area of either of the first and second
bodies. The thermally-conductive portion extends through an
aperture in the sheet.
[0015] Another aspect of the invention provides a flexible heat
exchanger comprising a volume having at least one inlet for
receiving a heat exchange fluid and at least one outlet. The volume
has a flexible wall essentially impermeable to the heat exchange
fluid. The wall carries a plurality of substantially-rigid members.
Each of the members comprises a thermally-conductive surface on an
outside of the wall and has a thermally-conductive portion
extending from the pad, through the wall and into the volume. The
thermally-conducting surface is either flush with or projects
outwardly from an outside surface of the wall.
[0016] Another aspect of the invention provides a method for making
a heat exchange surface for use in a heat exchanger. The method
comprises providing a sheet, the sheet being essentially impervious
to a heat exchange fluid to be used in the heat exchanger;
inserting thermally-conductive members through the sheet; and,
deforming at least one end of each of the thermally-conductive
members to cause the thermally-conductive member to sealingly
engage the sheet.
[0017] Another aspect of the invention provides a method for
cooling or warming a plurality of thermally-conductive heat
exchange surfaces suitable for placement against the skin of a
living subject to cool or warm the living subject. The method
comprises: establishing a turbulent flow of a heat exchange fluid
through a volume; allowing the heat exchange fluid to contact and
exchange heat with a plurality of thermally-conductive members
projecting into the volume through a flexible wall of the volume,
the thermally-conductive members each in direct thermal contact
with at least one of the heat exchange surfaces by way of an
unbroken path of a material or materials having a thermal
conductivity of at least 50 Wm.sup.-1K.sup.-1; and, allowing heat
to flow between the heat exchange surfaces and the
thermally-conductive members along the paths.
[0018] Another aspect of the invention provides a flexible heat
exchanger for warming or cooling a living subject. The heat
exchanger comprises a volume having at least one inlet for
receiving a heat exchange fluid and at least one outlet; and, a
flexible heat exchange plate essentially impermeable to the heat
exchange fluid, the plate comprising a plurality of substantially
rigid thermally-conductive members extending through a flexible
material of the plate from an outside surface of the plate into the
volume, the thermally-conductive members each projecting into a
volume by a distance of at least 2 mm.
[0019] Another aspect of the invention provides a flexible heat
exchanger comprising a volume having at least one inlet for
receiving a heat exchange fluid and at least one outlet; and, a
flexible plate essentially impermeable to the heat exchange fluid.
The plate comprises an array of closely-spaced apart substantially
rigid metal thermally-conductive members extending through a
flexible material of the plate, substantially at right angles to
inner and outer surfaces of the plate, from an outside surface of
the plate into the volume wherein a total area of the
thermally-conductive members exposed on the outer surface of the
plate exceeds a total cross sectional area of the
thermally-conductive members at a point where the cross sectional
members are extending through the flexible material.
[0020] Another aspect of the invention provides apparatus for
warming or cooling a living subject, the apparatus comprising a
plurality of heat exchangers and a mechanism for independently
regulating a supply of cooling or warming fluid circulated through
each of the heat exchangers. One aspect of the invention provides a
flexible heat exchanger for warming or cooling a living subject.
The heat exchanger comprises a volume having at least one inlet for
receiving a heat exchange fluid and at least one outlet. A heat
exchange fluid may be circulated through the volume. The heat
exchanger comprises a flexible heat exchange plate essentially
impermeable to the heat exchange fluid. The plate comprises a
flexible fluid-impervious membrane supporting a plurality of
substantially rigid thermally-conductive members. The
thermally-conductive members extend through the membrane from an
outside surface of the plate into the volume. Each of the
thermally-conductive members comprises a body, a portion extending
through the membrane from the body and a retainer member on a side
of the membrane opposite to the body. The membrane is gripped
between the body and the retainer member.
[0021] Another aspect of the invention provides a flexible heat
exchanger. The heat exchanger comprises a volume having at least
one inlet for receiving a heat exchange fluid and at least one
outlet. A heat exchange fluid, for example, water, can flow through
the volume. A flexible heat exchange plate essentially impermeable
to the heat exchange fluid has a plurality of substantially rigid
thermally-conductive members. The thermally-conductive members
extend through a flexible material of the plate from an outside
surface of the plate into the volume. The thermally-conductive
members conduct heat between a subject and the heat exchange
fluid.
[0022] Another aspect of the invention provides systems for heating
or cooling a subject. The systems have a reservoir holding heat
exchange fluid and a pair of feed pumps. One feed pump is connected
to deliver the heat exchange fluid to a heat exchanger. Another
feed pump is connected to withdraw the heat exchange fluid from the
heat exchanger. The rate at which the heat exchange fluid is
introduced into the heat exchanger by the first feed pump is
balanced with the rate at which fluid is withdrawn from the heat
exchanger by the second feed pump to maintain a pressure within a
volume in the heat exchanger within a desired range of an ambient
pressure.
[0023] One aspect of the invention provides a flexible heat
exchanger. The heat exchanger comprises a volume having at least
one inlet for receiving a heat exchange fluid and at least one
outlet. A heat exchange fluid may be circulated through the volume.
The heat exchanger comprises a flexible heat exchange plate
essentially impermeable to the heat exchange fluid. The plate
comprises a flexible fluid-impervious membrane supporting a
plurality of substantially rigid thermally-conductive members. The
thermally-conductive members extend through the membrane from an
outside surface of the plate into the volume. Each of the
thermally-conductive members comprises a body, a portion extending
through the membrane from the body and a retainer member on a side
of the membrane opposite to the body. The membrane is gripped
between the body and the retainer member.
[0024] Another aspect of the invention provides a flexible heat
exchanger. The heat exchanger comprises a volume having at least
one inlet for receiving a heat exchange fluid and at least one
outlet. A heat exchange fluid, for example, water, can flow through
the volume. A flexible heat exchange plate essentially impermeable
to the heat exchange fluid has a plurality of substantially rigid
thermally-conductive members. The thermally-conductive members
extend through a flexible material of the plate from an outside
surface of the plate into the volume. The thermally-conductive
members conduct heat between a subject and the heat exchange
fluid.
[0025] Another aspect of the invention provides systems for heating
or cooling an object. The systems have a reservoir holding heat
exchange fluid and a pair of feed pumps. One feed pump is connected
to deliver the heat exchange fluid to a heat exchanger. Another
feed pump is connected to withdraw the heat exchange fluid from the
heat exchanger. The rate at which the heat exchange fluid is
introduced into the heat exchanger by the first feed pump is
balanced with the rate at which fluid is withdrawn from the heat
exchanger by the second feed pump to maintain a pressure within a
volume in the heat exchanger within a desired range of an ambient
pressure.
[0026] Another aspect of the invention provides a heat exchanger
comprising front and rear sheet portions substantially impermeable
to a heat exchange fluid. The front sheet portion supports a
plurality of substantially rigid thermally-conductive members
extending through the front sheet portion and having inner portions
projecting into a volume between the front sheet portion and the
rear sheet portion. The thermally-conducting members have exposed
thermally-conducting surfaces on a front side of the front sheet
portion. The rear sheet portion is formed with indentations
receiving each of the inner portions of the plurality of
thermally-conductive members.
[0027] Other aspects of the invention provides flexible heat
exchange interfaces. The interfaces have plates or membranes
penetrated by substantially rigid thermally-conductive members. The
thermally-conductive members have enlarged pads on at least one
side of the plate or membrane. The flexible material allows the
interfaces to flex while the thermally-conductive members are
operative to channel heat from a higher-temperature side of the
interface to a lower-temperature side of the interface.
[0028] Another aspect of the invention provides a flexible heat
exchanger comprising a volume having an inlet and an outlet. The
volume can receive a heat exchange fluid, for example, water or a
water-based coolant. The heat exchanger includes a flexible plate.
Substantially rigid thermally-conductive members extend through a
flexible material of the flexible plate from an outside surface of
the flexible plate into the volume.
[0029] In preferred embodiments the thermally-conductive members
each have a thermal conductivity of at least 50 Wm.sup.1K.sup.1 and
preferably at least 100 Wm.sup.1K.sup.1. The thermally-conductive
elements may be made of materials such as aluminum, copper, gold,
silver, alloys of two or more of aluminum, copper, gold, or silver
with one another, alloys of one or more of aluminum, copper, gold,
or silver with one or more other metals, carbon, graphite, diamond,
or sapphire.
[0030] The thermally-conductive members may cover a substantial
portion of the outer surface of the flexible heat exchange plate in
some embodiments. For example, the thermally-conductive members may
be exposed in an area of 30% or 40% or more of an area of the
flexible heat exchange plate. In some embodiments, at least 50%, at
least 70% or even at least 80% of an area of the flexible heat
exchange plate is covered by the thermally-conductive members.
Because of the very high rate at which heat can be carried through
a thermally- conductive member, in some cases a coverage of 20% or
even less by the thermally-conductive members is sufficient.
[0031] The flexible material of the plate sheet or membrane may
comprise, for example, a suitable grade of polyurethane or other
suitable thermoplastic polymer. Examples of other materials that
may be suitable for use as the plate of membrane include: styrenic
copolymers; suitable grades of: polyvinyl chloride (PVC);
polyolefins such as polyethylene or polypropylene; styrenics such
as polystyrene; polyesters such as polyethylene terephthalate
(PET); polyethers such as polyetheretherketone (PEEK); polyamides
(e.g. NYLON.TM.); silicone; cellophane; cellulose acetates; natural
or synthetic rubbers; ethylene-vinyl acetate; neoprene;
polytetrafluoroethylene (PTFE e.g. TEFLON.TM.); plasticized
metallic films; a combination of two or more of these materials;
coated or impregnated fabrics; and the like. In some embodiments
the flexible material has a thermal conductivity not exceeding 5
Wm.sup.-1K.sup.-1.
[0032] A further aspect of the invention provides a temperature
control system comprising a heat exchanger according to the
invention, a reservoir containing a heat exchange fluid; a first
feed pump connected to feed heat exchange fluid from the reservoir
into the heat exchanger and a second feed pump connected to
withdraw the heat exchange fluid from the heat exchanger.
[0033] Further aspects of the invention and features of specific
embodiments of the invention are described below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] In drawings which illustrate non-limiting embodiments of the
invention:
[0035] FIGS. 1A, 1B and 1C are respectively a longitudinal
elevational cross-section view; a top plan view and a bottom plan
view of a flexible heat exchanger configured as a cooling/warming
pad for a subject's neck;
[0036] FIGS. 2A, 2B and 2C are respectively a cross-section view; a
bottom view; and a top view of the flexible heat exchange plate of
a heat exchanger according to an alternative embodiment of the
invention;
[0037] FIG. 2D is a partial view of the outside surface of a heat
exchanger having thermally-conductive members arranged in a
triangular array;
[0038] FIG. 2E is a partial view of the outside surface of a heat
exchanger having thermally-conductive members arranged to provide
converging lines of flexible material;
[0039] FIG. 2F is a view of the outside surface of a heat exchanger
having thermally-conductive members arranged in a rectangular array
oriented at an angle to a long axis of the heat exchanger;
[0040] FIGS. 3A, 3B and 3C are respectively a cross-section view; a
bottom view; and a top view of the flexible heat exchange plate of
a heat exchanger according to one embodiment of the invention;
[0041] FIGS. 4A through 4L are views of different heat conductors
that can be used in heat exchangers according to different
embodiments of the invention;
[0042] FIGS. 5A and 5B are respectively sectional and bottom views
of a flexible plate of a heat exchanger according to another
embodiment of the invention;
[0043] FIG. 6 is a section through a heat exchanger according to
another embodiment of the invention. FIGS. 6A, 6B and 6C are
respectively a cross section in the plane 6A-6A, a bottom plan
view, and a horizontal section through the heat exchanger of FIG. 6
(with the rear membrane removed);
[0044] FIGS. 6D, and 6E illustrate a heat exchanger in which a
pattern of seams provides a U-shaped channel; FIG. 6F shows another
heat exchanger in which a pattern of seams provides two separate
fluid paths through the heat exchanger;
[0045] FIGS. 7A through 7P illustrate some alternative
constructions for thermally-conductive members;
[0046] FIG. 8A illustrates a number of alternative configurations
for a pin in a thermally-conductive member; FIG. 8B illustrates a
number of alternative configurations for a base in a
thermally-conductive member; FIG. 8C illustrates a number of
alternative configurations for a retention member; FIG. 8D
illustrates a thermally-conductive member having a projecting
sealing ring; FIG. 8E shows some possible surface configurations
for bases of thermally-conductive members; FIG. 8F shows a
construction which includes a compliant washer;
[0047] FIGS. 9A through 9F illustrate some alternative
constructions for thermally-conductive members;
[0048] FIG. 10A shows a few possible alternative configurations for
a pin in a thermally-conductive member; FIG. 10B shows a few
possible shapes for a pin in a thermally-conductive member; FIG.
10C shows a few possible configurations for retainers for
thermally-conductive members of the types shown in FIGS. 10A and
10B;
[0049] FIGS. 11A through 11E illustrate extensions which may be
attached to thermally-conductive members to provide enhanced
thermal contact with a circulating fluid;
[0050] FIGS. 12A through 12C illustrate thermal conduction members
according to other alternative embodiments of the invention;
[0051] FIG. 13 is a cross section through a pin passing through a
membrane before the pin is deformed to seal to the membrane;
[0052] FIG. 13A is a top plan view of the pin of FIG. 13;
[0053] FIG. 14 is a cross section through the pin of FIG. 13 while
the pin is being deformed and the membrane is being carried into a
groove on the pin;
[0054] FIG. 15 is a cross section through the pin of FIG. 13 after
the pin has been deformed to seal to the membrane;
[0055] FIG. 15A is an enlarged view of one of the grooves shown in
FIG. 15;
[0056] FIGS. 16A, 16B, 16C, 16D, 16E and 16F are detailed views of
alternative configurations for the edge of a membrane retention
groove;
[0057] FIG. 17 illustrates a two-part through member according to
an alternative embodiment of the invention;
[0058] FIGS. 18A, 18B and 15C are cross sectional views of three
through members according to alternative embodiments of the
invention;
[0059] FIGS. 19A, 19B and 19C demonstrate the use of a through
member according to the invention to join together two or more thin
flexible sheets;
[0060] FIGS. 20A, 20B, 20C, 20D and 20E show a through member
according to an alternative embodiment of the invention; and, FIG.
21 shows a through member according to another alternative
embodiment of the invention.
[0061] FIGS. 22, 22A and 22B illustrate heat exchangers having rear
sheets affixed to thermally-conductive members;
[0062] FIGS. 23A and 23B illustrate embodiments of the invention in
which inner and outer surfaces of a membrane have different
characteristics;
[0063] FIGS. 24, 25, and 26 are schematic views of cooling systems
according to the invention;
[0064] FIG. 27 shows a heat exchanger adapted for cooling or
warming the neck of a subject;
[0065] FIGS. 28A, 28B and 28C show a heat exchanger like that of
FIG. 27 in position on the neck of a subject;
[0066] FIGS. 29A, 29B and 29C illustrate a heat exchanger system
comprising a heat exchanger configured to fit a subject's neck and
another heat exchanger configured to fit the subject's face;
[0067] FIGS. 30A, 30B and 30C illustrate a heat exchanger system
comprising a heat exchanger configured to fit a subject's neck,
another heat exchanger configured to fit the subject's face and
another heat exchanger configured to fit the subject's scalp;
[0068] FIG. 31 illustrates a heat exchanger system having heat
exchangers for warming or cooling a patient's head, torso and
thighs;
[0069] FIGS. 32A, 32B and 32C illustrate various heat exchangers
and fluid flow paths of the heat exchanger system of FIG. 31;
[0070] FIGS. 33A, 33B, 33C and 33D are schematic views of heat
exchangers according to embodiments of the invention being applied
to cooling various objects;
[0071] FIGS. 33E and 33F show heat exchangers having thermally
conductive members shaped to conform with a surface of an object to
be cooled;
[0072] FIG. 33G shows thermally-conductive members having ends
shaped in various ways;
[0073] FIG. 34 illustrates a heat exchanger according to an
embodiment of the invention being used to cool a high-temperature
object;
[0074] FIGS. 35A and 35B show heat exchangers according to
alternative embodiments of the invention
[0075] FIG. 36A is a top plan view of a heat exchange pad according
to an embodiment of the invention;
[0076] FIG. 36B is a bottom plan view of the heat exchange pad of
FIG. 36A;
[0077] FIG. 37A is a longitudinal section through the heat exchange
pad of FIG. 36A;
[0078] FIG. 37B is an enlarged portion of FIG. 37A;
[0079] FIG. 37C is an enlarged portion of FIG. 36A;
[0080] FIG. 37D is a transverse section through the heat exchange
pad of FIG. 36A;
[0081] FIG. 37E is an enlarged portion of FIG. 37D;
[0082] FIG. 37F is an enlarged top plan view of a heat exchanger
according to an alternative embodiment of the invention;
[0083] FIG. 37G is a top plan view of a heat exchange pad according
to another alternative embodiment of the invention;
[0084] FIGS. 38A, 38B and 38C are respectively a side elevation
view, an elevational cross section view, and a transverse cross
section view through a heat exchange pad according to the invention
wrapped around an outer surface of a cylindrical object;
[0085] FIGS. 39A, 39B and 39C are isometric views of three
different thermal reservoirs having integrated heat exchangers;
[0086] FIGS. 39D, 39E and 39F are respectively a top plan view, a
longitudinal elevational section, and a transverse elevational
section of a thermal reservoir according to another embodiment of
the invention;
[0087] FIGS. 39G and 39H are respectively a longitudinal
elevational section, and a transverse elevational section of a
thermal reservoir according to another embodiment of the
invention;
[0088] FIG. 40A through 40E are schematic views illustrating
cooling and heating systems according to various embodiments of the
invention;
[0089] FIG. 41 is a schematic view illustrating a cooling system
that uses a gaseous heat exchange fluid; and, FIGS. 42A, 42B and
42C are respectively a longitudinal section, a transverse section
and an enlarged view of a portion of a transverse section of a heat
exchange pad according to an alternative embodiment of the
invention.
DESCRIPTION
[0090] Throughout the following description, specific details are
set forth in order to provide a more thorough understanding of the
invention. However, the invention may be practised without these
particulars. In other instances, well known elements have not been
shown or described in detail to avoid unnecessarily obscuring the
invention. Accordingly, the specification and drawings are to be
regarded in an illustrative, rather than a restrictive, sense.
[0091] One aspect of this invention relates to pads useful for
transferring heat between a body and a heat exchange fluid. Where
the heat exchange fluid is warmer than the body, the pad
facilitates heat flow from the heat exchange fluid into the body
and the pad serves to warm the body. When the heat exchange fluid
is cooler than the body then the pad facilitates heat flow from the
body into the heat exchange fluid and the pad serves to cool the
body.
[0092] The heat exchange fluid may comprise a liquid, of which
water is an example, or a gas, of which air is an example. The heat
exchange fluid is provided at a suitable temperature by a suitable
temperature control system.
[0093] Some embodiments of this invention provide flexible heat
exchangers suitable for use in warming or cooling living subjects.
Heat exchangers according to the invention have a flexible heat
exchange plate. A plurality of thermal channels pass through the
flexible heat exchange plate. The flexible heat exchange plate has
a plurality of thermally-conductive members projecting through a
flexible medium that is essentially fluid-impermeable. The
thermally-conductive members provide effective means to accept heat
from a higher-temperature side of the medium, channel the heat
through the medium, and release the heat on a lower-temperature
side of the medium.
[0094] An outer side of the flexible heat exchange plate can be
brought into contact with a living subject. The
thermally-conductive members contact the skin of the subject. In
preferred embodiments, an inner side of the flexible heat exchange
plate forms one side of a channel which carries a heat exchange
fluid. Heat can be exchanged between the heat exchange fluid and
the subject's skin at a high rate by way of the
thermally-conductive members which extend directly from the
subject's skin into the heat exchange fluid.
[0095] The thermally-conductive members may be made of any suitable
thermally-conductive materials including thermally-conductive
metals, for example, aluminum, copper, gold, silver, or alloys of
these metals with one another and with other metals. The
thermally-conductive members may also be made of non-metals which
have high thermal conductivities such as carbon, suitable grades of
graphite, diamond, sapphire or the like. Preferably the
thermally-conductive members are made from materials having thermal
conductivities, k, of at least 50 Wm.sup.-1K.sup.-1 and preferably
at least 100 Wm.sup.-1K.sup.-1. All other factors being equal, it
is desirable that the material from which the thermally-conductive
members is made be relatively low in density to reduce the weight
of heat exchangers according to the invention. Where a heat
exchanger is made in a way that involves deforming the
thermally-conductive members, the material of the
thermally-conductive members is chosen to be malleable. For many
applications, aluminum is a good choice for the material of
thermally-conductive members. For many embodiments, soft 1300
series aluminum is a good choice of material for the
thermally-conductive members.
[0096] The thermally-conductive members are sized and located to
permit the thermally-conductive plate to be flexed sufficiently to
conform substantially to a part of a body of a living subject. The
thermally-conductive members are dimensioned and distributed in a
manner so that the thermally-conductive members cover a large
proportion of the area of the outer side of the flexible heat
exchange plate. In certain embodiments of the invention a plurality
of the thermally-conductive members cover more than 30% of an area
of the outer side of the flexible heat exchange plate. In some
embodiments 50% or more of an area of the outer side of the
flexible heat exchange plate is covered by the thermally-conductive
members.
[0097] In preferred embodiments of the invention a plurality of the
thermally-conductive members have thermally-conductive pins, fins,
bars or the like that project into the volume of a heat exchanger
to form an efficient heat exchange interface with heat exchange
fluid in the volume. The projecting pins, fins, bars, plates or the
like that form a heat exchange interface with the fluid inside the
volume of a heat exchanger may or may not be similar in shape or
other physical characteristics to the pins, fins, bars, plates or
the like that extend through the flexible medium to form a thermal
channel through the medium.
[0098] The following example embodiments of the invention will be
described in the context of cooling a living subject. Embodiments
of the invention could also be applied to warming a subject. As
noted below, embodiments of the invention could also be applied to
heating or cooling objects in other fields.
[0099] FIGS. 1A through 1C show a heat exchanger 10 according to an
embodiment of the invention. Heat exchanger 10 has a flexible heat
exchange plate 12 penetrated by a number of thermally-conductive
members 14. Plate 12 has an outer face 16 and an inner face 18.
Heat exchanger 10 has an inside volume 20 and ports 22, 23 by way
of which a heat exchange fluid can flow through volume 20. Volume
20 is defined on a front side by plate 12 and on a rear side by a
rear wall 24. Side walls 25 extend between plate 12 and rear wall
24. Plate 12, rear wall 24 and side walls 25 are all flexible so
that the outer surface 16 of heat exchanger 10 can conform to the
local contours of a portion of a subject's body to be cooled or
heated.
[0100] Thermally-conductive members 14 pass through the material 30
of plate 12. Inside ends 26 of thermally-conductive members 14
project into volume 20. Ends 26 preferably project significantly
into volume 20. In the illustrated embodiment, ends 26 are cut away
to provide increased surface area for heat transfer with fluid in
volume 20. Each inner end 26 comprises a number of prongs 27. Outer
faces 28 of thermally-conductive members can be placed against the
skin of a subject. Outer faces 28 may be outer faces of
thermally-conductive bodies (which may be called "bases") 29. Bases
29 are separated sufficiently to permit heat exchanger 10 to flex
in a desired degree but are preferably closely spaced to maximize
the area of outer faces 28 that can be placed against a desired
region on a subject. For example, in some embodiments, bases 29 are
spaced apart from one another by spacings in the range of 0.5 mm to
5.0 mm.
[0101] In some embodiments, each base 29 has a thickness in the
range of 0.5 mm to 5 mm. For example, in some embodiments base 29
has a thickness in the range of 1 mm to 2.5 mm. The size and
dimensions of base 29 in the plane of plate 12 may be chosen to
suit the application, and particularly depends on the contour of
the object to be cooled or heated. Thermally-conductive members 14
according to some embodiments of the invention for use in
cooling/warming pads for human subjects, have bases 29 having areas
in the range of 1 mm.sup.2 to 400 mm.sup.2. For such
cooling/heating pads the area is preferably in the range of 10
mm.sup.2 to 100 mm.sup.2.
[0102] Thermally-conductive members 14 may have reduced cross
sectional areas in their portions inward from bases 29. The
cross-sectional area of thermally-conductive members 14 at the
point that thermally-conductive members 14 emerge from material 30
on the inside face of plate 12 may, for example, be in the range of
20% to 100%, and preferably 35% to 65%, of the area of base 29.
[0103] Plate 12 comprises a flexible sheet or membrane through
which thermally-conductive members 14 project. The membrane may be
made of a flexible material or materials 30. Thermally-conductive
members 14 have lengths sufficient to pass through material 30. In
preferred embodiments, members 14 project into volume 20.
Thermally-conductive members 14 may, for example, project into
volume 20 for a distance in the range of 0 mm to 20 mm. In some
embodiments intended for warming or cooling a living subject,
thermally-conductive members 14 project into volume 20 for a
distance in the range of 2 mm to 10 mm. In some embodiments members
14 project past material 30 by at least 3 mm. The portions of
members 14 which project into volume 20 may also function as
supports to maintain a minimum spacing between rear wall 24 and
plate 12.
[0104] It is not necessary that all thermally-conductive members 14
be identical or that all thermally-conductive members 14 have
equal-sized bases 29 although it is convenient to make heat
exchanger 10 with thermally-conductive members 14 substantially the
same as one another.
[0105] Material 30 constitutes a flexible membrane through which
thermally-conductive members 14 extend. In some embodiments, rear
wall 24 is made of material 30. Substantially all of heat exchanger
10, except for thermally-conductive members 14, may be made of the
same material or materials 30. Material 30 is preferably flexible
and/or elastically stretchable. Material 30 may, for example,
comprise any of a variety of suitable flexible polymers such as
natural rubber, polyurethane, polypropylene, polyethylene,
ethylene-vinyl acetate, polyvinyl chloride, silicone, a combination
of these materials, a coated fabric, or the like. Material 30, or
portions of material 30 may optionally be loaded with particles of
one or more thermally-conductive materials such as metal or
graphite. However, since material 30 is not required to play a
significant role in conducting heat, material 30 may be a material
having a low thermal conductivity not exceeding 5 Wm.sup.-1K.sup.-1
without significantly impairing the function of heat exchanger 10.
In some embodiments, material 30 has a hardness in the range of 10
to 80 on the Shore A hardness scale.
[0106] One specific example embodiment of the invention is
constructed as shown in FIGS. 1A to 1C and is designed to be
applied to the neck of a human subject to cool the subject's brain.
This embodiment of heat exchanger 10 has approximately 50
thermally-conductive members 14 arranged in a rectangular array.
Each member 14 has nine pins which project into volume 20. Bases 29
have areas of about 10 mm.times.10 mm and thicknesses of about 2
mm. Each of the pins has a diameter of about 1.8 mm. The total
length of each of the pins is about 10 mm. The thickness of
material 30 in the walls of heat exchanger 10 is about 4 mm. Two
short tubes of approximately 10 mm inner diameter provide inlet and
outlet ports 22 and 23. A heat exchange fluid 65 such as cold water
may be circulated through volume 20.
[0107] Two such heat exchangers may be dimensioned so that they can
be applied to a subject's neck respectively over the left and right
carotid arteries to cool the subject's brain by cooling blood
flowing to the subject's brain. The heat exchangers are
sufficiently flexible to conform substantially to the curvature of
the subject's neck without causing unacceptable pressure spots. The
heat exchangers may be held in place under a collar, such as a foam
collar.
[0108] Plate 12 may be fabricated using any suitable process. For
example, plate 12 may be made by making holes in a sheet of
material 30 and inserting thermally-conductive members 14 through
the holes. The holes may initially have dimensions smaller than
corresponding dimensions of thermally-conductive members 14 so that
material 30 seals around thermally-conductive members 14
sufficiently to prevent any significant loss of heat exchange fluid
from volume 20. Additionally, or in the alternative, a sealant,
such as a suitable glue may be provided to enhance the seal between
thermally-conductive members 14 and material 30. Plate 12 may also
be made by a suitable plastic manufacturing process such as thermal
injection molding, reaction injection molding, compression molding,
vacuum forming or casting. In this case, thermally-conductive
members 14 may be molded into plate 12.
[0109] The thickness of material 30 in plate 12 can be selected to
provide a desired compromise between flexibility and durability.
Since heat exchanger 10 does not rely on material 30 to conduct
heat, it is not necessary to make material 30 extremely thin to
improve heat conduction. Material 30 may, for example, have a
thickness in the range of about 0.1 mm to 20 mm. In some
embodiments of the invention, material 30 has a thickness in the
range of 4 mm to 7 mm in plate 12. When thermally-conductive
members of types which grip material 30 from either side (as shown
for example in FIG. 4I to FIG. 4L or 7A to 7P) are used, the
thickness of material 30 may be smaller, for example, as little as
about 1 mm in plate 12.
[0110] Projections of material 30 or some other material may
optionally extend into volume 20. Such projections may be
positioned to support wall 24 relative to plate 12, to direct the
flow of fluid 65 within volume 20 and/or to induce turbulence at
selected locations in the flow of fluid 65 in order to provide
enhanced thermal contact between thermally-conductive members 14
and fluid 65.
[0111] Thermally-conductive members 14 may be arranged in a wide
range of patterns. For example, as shown in FIGS. 1A to 1C and 3A
to 3C, members 14 may be arranged in a number of rows and columns
to form a rectangular array, which could be a square array. In some
embodiments, members 14 are arranged in rows or columns which are
shifted relative to one another as shown in FIGS. 2B and 2C. This
arrangement creates increased turbulence in fluid 65 flowing
through volume 20 and hence increases the efficiency of heat
transfer between the inside ends of thermally-conductive members 14
and fluid 65. In some embodiments, bases 29 of members 14 are
arranged in a rectangular array as illustrated, for example, in
FIG. 1, while portions of members 14 which project into volume 20
are arranged in rows or columns which are shifted relative to one
another as shown in FIGS. 2B and 2C. In some embodiments, members
14 are arranged in a triangular array, as shown in FIG. 2D.
[0112] Flexing of plate 12 may be facilitated by arranging members
14 to provide substantially unbroken lines 31 of material 30
extending generally parallel to one or more axes about which a user
may wish to flex heat exchanger 10. The embodiment shown in FIG. 1B
shows two sets of lines 31 of material 30 which extend between
adjacent rows and columns of members 14. The embodiment illustrated
in FIG. 2B has one set of parallel lines 31. Lines 31 are not
necessarily parallel to one another. For example, FIG. 2E
illustrates an arrangement of members 14 which facilitates flexing
in such a way as to conform to a portion of the surface of a cone.
The array of members 14 is not necessarily aligned with any axis of
heat exchanger 10. For example, FIG. 2F shows the outside face of a
heat exchanger wherein thermally-conductive members 14 are arranged
in a rectangular array oriented at an angle, .phi., to a long axis
of the heat exchanger.
[0113] FIGS. 1A to 1C and 2A to 2F illustrate heat exchangers in
which faces 28 are substantially flush with material 30 on outer
face 16. This arrangement facilitates cleaning, as outer face 16 is
substantially smooth. FIGS. 3A to 3C illustrate an alternative
embodiment of the invention wherein base 29 is not embedded in
material 30. In this embodiment faces 28 are spaced outwardly from
material 30. The embodiments illustrated in these Figures can be
fabricated, for example, by inserting thermally-conductive members
14 though holes formed in a sheet of material 30.
[0114] Thermally-conductive members 14 may take any of a wide
variety of forms which provide the function of carrying heat in
either direction between a subject on one side of the flexible
plate and a heat exchange fluid 65 or other matter on an opposed
side as the flexible plate that is warmer or cooler than the
subject. Ideally, members 14 provide: [0115] good thermal
interfaces between the thermally-conductive members and the subject
to be cooled or warmed; [0116] good thermal channels across
flexible material 30; and [0117] good thermal interfaces between
the thermally-conductive members and the fluid in volume 20 of the
thermal exchanger. Some possible forms for members 14 are
illustrated in FIGS. 4A through 4L. It is understood that these are
possible forms and are included only as examples. Modifications to
these examples can be made to obtain a much larger list of
examples. In addition, features illustrated in these examples can
be exchanged or combined partially or fully to obtain an even
larger list of examples.
[0118] FIG. 4A shows a thermally-conductive member 14A having a
square base 29 and cylindrical pin 32. Pin 32 can carry heat
through material 30 and constitutes a means for channelling heat
through flexible material 30 and releasing heat into (or taking
heat from) fluid in volume 20 of a heat exchanger. FIG. 4B shows a
thermally-conductive member 14B having a circular base 29 instead
of a square base. It is generally preferable that the
thermally-conductive surfaces that contact a subject's skin be
rounded and not have sharp corners.
[0119] FIG. 4C shows a thermally-conductive member 14C wherein both
base 29 and the pin 32 are square in cross-section (like the
thermally-conductive members of FIGS. 2A to 2C). FIG. 4D shows a
thermally-conductive member 14D similar to member 14A except that
pin 32 has a circumferential groove 33 in its part close to base
29. Groove 33 receives extra material 30 in an injection molding or
casting process to better seal member 14D to material 30. FIG. 4E
shows a thermally-conductive member 14E wherein a tip of pin 32 is
tapered to facilitate insertion into a hole in a sheet of material
30.
[0120] FIG. 4F shows a thermally-conductive member 14F having a
pair of platelike rectangular conductors 34 which serve both as
thermal channels through material 30 and as structures for
releasing heat into (or taking heat from) volume 20. Conductors 34
may be arranged in a V-shape to better transfer heat to fluid
flowing past plates 34. Plate-like conductors could also be
arranged in other manners such as being parallel with each other.
Thermally-conductive member 14F has the advantage in manufacturing
that it can be made by cutting and folding thermally-conductive
sheet material.
[0121] FIG. 4G shows a thermally-conductive element 14G having a
thermal channel portion provided by a tubular pin 36. FIG. 4H shows
a thermally-conductive member 14H having multiple pins 38 extending
from base 29. Pins 38 provide multiple thermal channels extending
from the same base 29 and projecting into the volume 30. Conductive
member 14H advantageously provides increased contact area between
conductive member 14H and a heat transfer fluid 65 in volume 20.
FIGS. 41 and 4J show a thermally-conductive member 14I that is
designed to reduce the possibility of fluid leaking between
material 30 and member 14I. Member 14I may be fabricated in
two-pieces 14I-1 and 14I-2 that can be assembled together in a
manner that provides good thermal contact between pieces 14I-1 and
14I-2.
[0122] In the illustrated embodiment, one of the pieces of member
14I has a pin 39 which is received in a corresponding socket 40
(see FIG. 4J) in the other piece. Pin 39 may have an interference
fit in socket 40 to keep the two pieces tightly together and to
provide good heat transfer between the pieces. A circumferentially
extending groove 41 is defined between pieces 14I-1 and 14I-2.
Groove 41 receives material 30. The faces of pieces 14I-1 and 14I-2
which contact material 30 may be undercut to provide ridges 42
which help to prevent fluid from leaking past member 14I. The
pieces of multi-piece thermally-conductive members may be fastened
together in other ways which provide thermal contact between the
pieces. For example, fastening means such as screws, rivets, or the
like may be provided. FIGS. 4K and 4L show a thermally-conductive
member 14K that is similar to member 14I but is an integral part.
Member 14K is designed to be cramped onto material 30. Material 30
projects into a groove 43. The sides of the groove 43 may be
cramped together to hold material 30 around the edges of member 14K
as shown in FIG. 4L.
[0123] FIGS. 5A and 5B show a flexible fluid heat exchanger 50
which is normally curved in the absence of applied forces. Heat
exchanger 50 may be used to apply heat to or to cool a
substantially cylindrical object such as a subject's limb. Apart
from being curved, heat exchanger 50 is similar to heat exchanger
10 of FIGS. 1A through 1C.
[0124] FIGS. 6 through 14B illustrate various embodiments of heat
exchanger according to the invention in which thermally-conductive
members extend through apertures in a fluid impermeable membrane
and are held in place by retention members. FIG. 6 shows a heat
exchanger 110 having a volume 120 defined within a membrane 130.
Membrane 130 comprises a layer of a suitable flexible
fluid-impermeable material. Membrane 130 has a thickness adequate
to provide a desired strength. Membrane 130 may be thin. For
example, in some embodiments, membrane 130 has a thickness of 0.010
inches or less.
[0125] Membrane 130 may comprise, for example, a suitable grade of
polyurethane or other suitable thermoplastic polymer. Examples of
other materials that may be suitable for use as membrane 130
include: styrenic copolymers; suitable grades of: polyvinyl
chloride (PVC); polyolefins such as polyethylene or polypropylene;
styrenics such as polystyrene; polyesters such as polyethylene
terephthalate (PET); polyethers such as polyetheretherketone
(PEEK); polyamides (e.g. NYLON.TM.); silicone; cellophane;
cellulose acetates; natural or synthetic rubbers; ethylene-vinyl
acetate; neoprene; polytetrafluoroethylene (PTFE e.g. TEFLON.TM.);
plasticized metallic films; combinations of two or more of these
materials; coated or impregnated fabrics; and the like.
[0126] Thermally-conductive members 114 penetrate membrane 130.
Each thermally-conductive member 114 has a pad (which may also be
called a base) 129 on an outer side of membrane 130 and a pin
portion 132 which projects into volume 120 and is in thermal
contact with a fluid 65 in volume 120. Base 129 may be a body
formed in or attached to thermally-conductive member 114.
Thermally-conductive members 114 are held in place by retention
members 115.
[0127] As shown in FIGS. 6A, 6B and 6C, membrane 130 may be affixed
to itself, for example by adhesive bonding or by welding at seams
117, to form channels 119. In the embodiment illustrated in FIGS. 6
through 6C, front and rear sheets 130A and 130B of membrane 130 of
heat exchanger 110 are joined together in a pattern which provides
a single sinuous channel 119 which extends between ports 122 and
123. Ports 122 and 123 are attached to membrane 130 with a suitable
fluid-impermeable attachment means such as welding, suitable
adhesive, stitching, taping, or the like. Front and rear sheets
130A and 130B are not necessarily equal in thickness. In some
embodiments, front sheet 130A is thicker than rear sheet 130B.
[0128] In a currently preferred embodiment of the invention, rear
sheet 130B is vacuum formed, or otherwise shaped, to provide a
dimple corresponding to each of the thermally-conductive members
(e.g. 114). Thermally-conductive members 114 project into the
corresponding dimples. This can yield a structure which remains
highly flexible and resistant to "ballooning" as heat exchange
fluid 65 is pumped through it. With this construction the volume
surrounding thermally conductive members 114 can be made small,
thereby reducing the weight of the fluid-filled heat exchanger.
Front and rear sheets 130A and 130B may be affixed together at
locations which define one or channels which each have a single row
of thermally-conductive members extending along the channels. The
locations at which front and rear sheets 130A and 130B are affixed
together may be just far enough apart to be on either side of the
thermally-conductive members 114. The channels may be straight,
serpentine, U-shaped, or follow alternative paths as convenient for
the application at hand. One can appreciate that as one moves along
the centerline of one of the channels the rear sheet 130B bumps
away from the front sheet 130A in each dimpled portion and is close
to, even touching or almost touching front sheet 130A in its
portions between thermally-conductive members 114.
[0129] In some embodiments of the invention, the heat exchanger has
"drape". This means that when the heat exchanger is placed over a
horizontal member, such as a thin horizontal dowel or a pencil, the
overhanging parts of the heat exchanger hang down substantially
vertically from the horizontal member. A heat exchanger which has
drape can conform readily to the surface contours of a person or
object against which it is brought.
[0130] FIGS. 6D and 6E illustrate a heat exchanger in which the
pattern of seams 117 provides a U-shaped channel 119. By comparing
FIGS. 6A through 6C to FIGS. 6D and 6E it can be seen that the
width of channel 119 may be varied. In some embodiments channel 119
is narrow and accommodates only a single row of
thermally-conductive members 114. In other embodiments, channel 119
is wider and can accommodate several thermally-conductive members
114 side-by-side. As described above, there are many variations in
the placement of thermally-conductive members 114. FIG. 6F shows
another heat exchanger in which a pattern of seams 117 provides two
separate paths through the heat exchanger. Each path has ports
which provide an inlet and outlet for the path.
[0131] FIGS. 7A and 7B illustrate a thermally-conductive member
114A. As shown in FIG. 7A, thermally-conductive member 114A has a
shoulder 121 which projects through membrane 130 and through an
aperture 115A in retention member 115. As shown in FIG. 7B,
shoulder 121 is deformed, for example by pressing, to firmly engage
retention member 115 and to compress membrane 130 between retention
member 115 and base 129. In some embodiments, shoulder 121
initially projects past retention member 115 just far enough that
it provides a good seal when pressed flush with retention member
115. Aperture 115A may have various profiles, for example, it may
be tapered, as shown in FIGS. 7A and 7B or straight-sided, as shown
in FIGS. 7A-1, 7B-1, 7A-2 and 7B-2.
[0132] FIGS. 7C and 7D show a thermally-conductive member 114B. Pin
132 of thermally-conductive member 114B has a sharp end 132A and a
cross sectional profile which matches the cross sectional profile
of retention member 115B. Thermally-conductive member 114B does not
require a pre-existing aperture in membrane 130. Pin 132 and
retention member 115B cooperate as a punch and die. As pin 132 is
pressed into the aperture in retention member 115B through membrane
130, the end of pin 132 punches an aperture in membrane 130 which
matches the cross sectional shape of pin 132. Pin 132 is a friction
fit in the aperture of retention member 115B.
[0133] FIGS. 7E and 7F illustrate an alternative
thermally-conductive member 114C wherein pin 132 is threaded and
the retention member comprises a washer 115C which is compressed
against membrane 130 by a nut 115D.
[0134] FIGS. 7G and 7H illustrate an alternative
thermally-conductive member 114D which is adhered to membrane 130
by a suitable adhesive. Thermally-conductive member 114D may be
used with or without a retention member as shown in FIGS. 7G and 7H
or with a retention member as shown in FIGS. 7I and 7J. In some
embodiments, a retention member 115 is secured to membrane 130 with
a suitable adhesive.
[0135] FIGS. 7K, 7L, 7K-1, 7L-1, 7K-2 and 7L-2 illustrate
alternative constructions wherein pin 132 of a thermally-conductive
member 114E is deformed and shaped into a head 132B which bears
against membrane 130. A washer may be provided between head 132B
and membrane 130. This configuration is the basis for a currently
preferred embodiment of the invention.
[0136] In other embodiments of the invention (not shown), a part of
thermally-conductive member 114 projects from an enlarged body in
volume 120 through an aperture in membrane 130. The projecting part
of thermally-conductive member 114 is subsequently deformed, for
example by pressing, to form an enlarged base on the outside of
membrane 130. The membrane is held between the body in volume 120
and the enlarged base.
[0137] FIGS. 7M and 7N illustrate a construction in which a
thermally-conductive member 114F is held against membrane 130 by a
spring clip 115-2.
[0138] FIGS. 7O and 7P illustrate a construction wherein a
retaining member 115 is deformed, for example by pressing, to seal
against pin 132 and membrane 130.
[0139] Many variations in the design of a thermally-conductive
member 114 and retention member 115 are possible within the scope
of the invention. Thermally-conductive member 114 and retention
member 115 may be made of the same material. If they are made from
different materials then it is desirable that the coefficients of
thermal expansion of the materials of thermally-conductive member
114 and retention member 115 be such that retention member 115 does
not tend to loosen as a heat exchanger is used. For example, where
a heat exchanger is to be used for cooling applications it is
desirable that retention member 115 have a coefficient of thermal
expansion that is the same as or greater than that of pin 132.
[0140] FIG. 8A shows a few possible forms for pin 132. Pin 132 may
have any of a wide range of cross-sectional shapes. FIG. 8B shows a
few possible shapes for base 129. FIG. 8C shows a few possible
configurations for retention member 115. Retention members 115-1
and 115-2 are spring clips, sometimes known as push retainers.
Retention members 115-1 and 115-2 have inner edge portions 118
which tightly engage pin 132. The retention member used to retain a
thermally-conductive member 114 typically has an outer profile
which matches that of the base 129 of the thermally-conductive
member 114 although this is not necessary. In some embodiments of
the invention a compliant member, such as an 0-ring or compliant
washer is provided between retention member 115 and membrane 130,
between base 129 and membrane 130, or both. FIG. 8F shows a
construction which includes a compliant washer.
[0141] In some embodiments of the invention, retention member 115,
base 129, or both have one or more narrow projecting rings 131 or
grooves (FIG. 8D) to provide an enhanced seal with membrane 130.
FIG. 8E shows some possible surface configurations for bases 129.
Bases 129 may be roughened or profiled to provide increased surface
area and consequentially improved thermal conductivity between
bases 129 and an adjacent compliant surface, such as the surface of
a subject's skin.
[0142] FIGS. 9A through 9F show some alternative embodiments of the
invention in which thermally-conductive members have an enlarged
portion within volume 120 and are held to membrane 130 by a
retainer located on the outer side of membrane 130. FIGS. 9A and 9B
show a thermally-conductive member 114G which comprises a pin 132
which projects into volume 120 from an enlarged portion 133. A pin
135 extends from enlarged portion 133 through membrane 130. Pins
132, 135 and enlarged portion 133 are conveniently integral with
one another. A retainer 137 engages pin 135 to hold
thermally-conductive member 114G in place and sealed to membrane
130. Pin 132 may project through retainer 137, as shown in FIGS. 9A
and 9B. In some embodiments retainer 137 covers the end of pin
132.
[0143] FIGS. 9C and 9D illustrate another thermally-conductive
member 114H in which pin 135 is threaded and retainer 137 is in the
form of a nut that screws onto pin 135. In the illustrated
embodiment, the portion of retainer 137 that contacts membrane 130
is smaller than the body-contacting end of retainer 137. This
enhances the flexibility of the heat exchanger.
[0144] FIGS. 9E and 9F show another thermally-conductive member
114I wherein retainer 137 is a press fit onto pin 135.
[0145] Many variations are possible in the embodiments of the
invention illustrated in FIGS. 9A through 9F. Pins 132 and 135 may
have the same cross sectional shape, as shown in FIGS. 9E and 9F or
may have different cross sectional shapes, as shown in FIGS. 9A and
9B.
[0146] FIGS. 10A through 10C show thermally-conductive members that
may be used in embodiments like those of FIGS. 9A through 9F. FIG.
10A shows a few possible forms for pin 135. In the embodiments of
FIG. 10A, enlarged portion and pin 132 have the same diameter. Pin
132 may have any of a wide range of cross-sectional shapes. FIG.
10B shows a few possible shapes for pin 132 in thermally-conductive
members which also have a pin 135. FIG. 10C shows a few possible
configurations for retainers 137.
[0147] Some embodiments of the invention provide an extension on
one or more of pins 132 which provides additional surface area for
thermal contact with fluid 65. The extension may be in the form of
a cap affixed to the end of pin 132. Various forms of extension are
shown in FIGS. 11A through 11E. FIG. 11A shows an extension 141A
shaped generally like a mushroom cap. FIG. 11B shows an extension
141B in the form of a cylinder. FIG. 11C shows an extension 141C
shaped generally like a football in side elevation and star-shaped
in cross section. FIG. 11D shows a fin-shaped extension 141D. FIG.
11E shows a tear-drop-shaped extension 141A. The extensions may be
made of the same class of materials as pins 132 and are in good
thermal contact with pins 132. In some embodiments, extensions are
formed integrally with pins 132.
[0148] FIGS. 12A through 12C illustrate some further alternative
embodiments of the invention. As shown in FIG. 12A, a single base
129 may have multiple pins 132 which extend through membrane 130
and are held in place by a single retainer member 115-3. As shown
in FIG. 12B, multiple thermally-conductive members 114 may be held
in place by a single retainer member 115-4. As shown in FIG. 12C, a
single base 129 having multiple pins 132 passing through membrane
130 may be held in place by multiple retainer members 115-5.
[0149] FIGS. 13 to 21 show members adapted to be sealed to a
membrane or other flexible material and methods for installing such
members. A number of the embodiments of FIGS. 13 to 21 are suitable
for use as thermally-conductive members in heat exchangers
according to the invention. FIG. 13 shows a pin 210 passing through
an aperture 212 in a membrane 214. Pin 210 has a head 220 on a
first side 214A of membrane 214. Pin 210 has a shaft 222 which
extends through aperture 212 and projects on a second side 214B of
membrane 214. A groove 224 in head 220 extends around the base of
shaft 222. Groove 224 is wide enough to receive an edge portion
214C of membrane 214.
[0150] As shown in FIG. 14, shaft 222 can be deformed, for example,
by compressing shaft 222 toward head 220 with a press 228. As the
deformation occurs, the material on the outside of shaft 222 in its
lower portion 222A near head 222 tends to move outwardly and
downwardly as indicated by arrows 230.
[0151] Edge portion 214C of membrane 214 fits closely to shaft 222.
The deformation of lower portion 222A of shaft 222 carries edge
portion 214C of membrane 214 into groove 224. Continued deformation
of shaft 222 moves edge portion 214C deeper into groove 224.
Eventually the continued deformation of shaft 222 moves inner wall
224A of groove 224 toward outer wall 224B of groove 224 so that
edge portion 214C of membrane 214 becomes gripped between inner
wall 224A and at least a portion of outer wall 224B as shown in
FIG. 15. Typically membrane 214 is gripped first between inner wall
224A and corner 224C at which outer wall 224B meets surface 220A of
head 220 which surrounds groove 224.
[0152] It is thought that providing a smooth or even polished
surface on the portion of shaft 222 contacted by the edge of a
sheet 214 during deformation of shaft 222 will help the edge of
sheet 214 to slide down shaft 222 into groove 224. It is also
thought that the edges of sheet 214 will be drawn most effectively
into groove 224 if the edges of sheet 214 is at least somewhat
elastic.
[0153] In some embodiments of the invention, membrane 214 is
impervious to fluids and pin 210 makes a fluid-tight seal to
membrane 214. Membrane may be of any suitable flexible material. In
some embodiments of the invention, membrane 214 comprises an
elastic material, such as urethane. Membrane 214 could comprise any
of a variety of suitable flexible sheet like materials. Some
examples are polymers such as natural rubber, polyurethane,
polypropylene, polyethylene, ethylene-vinyl acetate, polyvinyl
chloride, silicone, a combination of these materials, fabrics, or
the like.
[0154] Pin 222 may be of any suitable material which is
sufficiently ductile to be plastically deformed by pressing, as
described above. Where pin 222 is to operate as a
thermally-conductive member in a heat exchanger then the material
of pin 222 should be highly thermally-conductive. For example, pin
222 may be made of aluminum, copper, or another plastically
deformable metal having good thermal conductivity. Other metals or
materials commonly used to make blind or solid rivets could be
used. Some examples of such metals include suitable steels,
stainless steels; brasses; bronzes; monel (a nickel-copper alloy);
and inconel (a nickel-chromium alloy). Some successful prototypes
have used 1100 series aluminum having a hardness of about 32 on the
Brinell hardness scale for shaft 222. The other materials listed
above typically have hardnesses in the range of about 20 and about
200 on the Brinell hardness scale. In applications in which pin 222
is not required to conduct heat, deformable plastics such as
suitable grades of polyurethane, polyethylene, polypropylene, PVC
or poly carbonate could also be used for shaft 222.
[0155] As shown in FIGS. 16A to 16F, the profile of groove 224 may
be varied. It may be desirable to provide a relieved corner or
"lip" 224C where outer wall 224B of groove 224 intersects surface
220A of head 220. In some embodiments of the invention the main
seal between pin 210 and membrane 214 occurs at the nip 232 (FIG.
15) between corner 224C and the deformed shaft 222. Providing a
relieved corner 224C provides increased surface area in the seal
and also facilitates membrane 214 being moved into groove 224.
[0156] FIG. 16A shows a groove 224 having a sharp outside corner
214C. FIG. 16B shows a groove 224 having a bevelled outside corner
214C-1. FIG. 16C shows a groove 224 having a rounded outside corner
224C-2. FIG. 16D shows a groove 224 wherein outside corner 224C-3
is elevated above the surrounding surface of face 220A of head 220.
FIG. 16F shows a groove 224 having an outer wall 224B which is
inclined away from shaft 222.
[0157] It is convenient, although not mandatory, to make head 220
and shaft 222 integral with one another. Head 220, including the
outer wall 224B of groove 224 does not need to be deformable as
does shaft 222. In some embodiments, shaft 222 and head 220 could
comprise separate parts which are suitably affixed to one another.
An example of such a construction is depicted in FIG. 17.
[0158] FIG. 17 shows a through-member 240 having a first part 242
which includes a plastically deformable shaft 243 having an
enlarged head 244 at one end. A second part 245 has an aperture
246. Shaft 243 projects through aperture 246. A groove 248 is
defined between shaft 243 and a wall 249 of a counterbored part
246A of aperture 246. Second part 245 may be made of a harder
material than first part 242.
[0159] FIG. 18A illustrates a through member 260 according to an
alternative embodiment of the invention in which shaft 262 is
tubular. FIG. 18B illustrates a through member 264 according to
another alternative embodiment of the invention in which shaft 266
is semi-tubular. A tubular or semi-tubular shaft can be deformed
with the application of less force than would be required to deform
a solid shaft made out of the same material.
[0160] A through member may be configured as a blind rivet. FIG.
18C shows a through member 270 configured as one type of blind
rivet. Through member 270 has an actuating stud 272 passing through
a hollow shaft 274. Actuating stud 272 has an enlarged head 276 and
a weakened portion 278. Through member 270 can be installed by
pulling on the projecting shank 279 of actuating stud 272. This
causes head 276 to compress shaft 274 and to deform shaft 274
outwardly. As shaft 274 is deformed, a membrane 214 is drawn into
and becomes affixed within a groove 224 as described above.
Eventually enough tension can be applied to shank 279 to cause
actuating stud 272 to break off at weakened portion 278. In typical
embodiments, shaft 274 is a soft deformable material such as
aluminum or a suitable grade of stainless steel while stud 272 is
of a harder material such as steel.
[0161] The invention could also be embodied in blind rivets of
other types which have a shaft which in deforms outwardly when the
blind rivet installed in a manner such that a membrane 214 or other
material through which the blind rivet passes is moved into and
retained in a groove by the deformation of the shaft.
[0162] A through member according to the invention may be used to
join together two or more sheets of material. FIGS. 19A, 19B and
19C, show the application of a through member 280 to join together
two or more sheets of material. Through member 280 may be
constructed and used as described above. Through member 280 is
similar to the through member 210 of FIG. 13 except that groove 224
has been made wider. In this embodiment, groove 224 is wide enough
to receive edges 214-1C and 214-2C of each of the sheets 214-1 and
214-2 of material being joined together. Even where the sheets of
material are flexible it is not necessary to provide a washer or
other separate fastening component on the side of the material
sheets away from head 220. Through members according to other
embodiments of the invention described herein, including the blind
rivet embodiments, could also be used to attach multiple sheets of
material together.
[0163] FIGS. 20A through 20E depict stages in the installation of a
though member 290 according to an alternative embodiment of the
invention. Through member 290 has a square shaft 291 extending from
a head 292. An aperture 293 extends through shaft 291. A groove 294
extends around the base of shaft 291. Shaft 291 passes through an
aperture in a sheet 214 of a flexible material.
[0164] As shown in FIG. 20C, deformation of shaft 291 causes the
outward faces of shaft 291 to be tapering toward groove 294. This
urges the edges of sheet 214 into groove 294. Continued deformation
of shaft 291 results in the edges of sheet 214 being captured in
groove 294 between the outer face of shaft 291 and the outside
corner (or "lip") of groove 294.
[0165] Another aspect of the invention provides a method for
securing a through member in a membrane. The method begins with
providing a through member having a head, a shaft extending from
the head and a groove surrounding the shaft. The shaft is inserted
through an aperture in a membrane to which the through member is to
be secured. The method continues by compressing the shaft of the
through member longitudinally and thereby deforming the shaft such
that an initial deformation of the shaft moves an edge portion of
the membrane into the groove of the through member. The method
continues by continuing to compress the shaft longitudinally until
the shaft deforms sufficiently to cause the edge portion of the
membrane to be gripped between an outer surface of the deformed
shaft and an outer wall of the groove.
[0166] This method may be used to secure a one-piece through member
securely, and in some embodiments sealingly, to a membrane or to
multiple membranes or other sheet-like materials in a single
operation. It is not necessary to assemble multiple pieces to
provide the through member or to perform multiple operations
(although the invention could be applied to through members
assembled from more than one part or to methods involving
additional steps). The through member may be introduced from one
side of the membrane (or other sheet like material(s)) to which the
through member is being affixed. It is not necessary to introduce
different parts of the through member from different sides of the
membrane.
[0167] Head 220 may carry or be attached to some structure which is
to be attached to membrane 214. For example, head 220 may carry a
snap and membrane 214 may comprise a cover for something, an
article of clothing, or the like. A through member according to the
invention may be apertured. A valve, stopper or orifice for
allowing air, another gas or a liquid to flow through the aperture
may be provided in the aperture. A through member may have a
threaded aperture capable of receiving a screw or may have a
projecting stud. A through member could carry alternative
structures such as electrical connectors. In some embodiments of
the invention the through member is electrically conductive or has
one or more electrical conductors which join electrical connectors
on opposing sides of membrane 214.
[0168] Various alterations and modifications are possible in the
construction and installation of through-members as illustrated in
FIGS. 13 to 20 without departing from the invention. For example:
[0169] shaft 222 is not necessarily circular, as illustrated, but
could have another cross sectional shape, such as slightly
elliptical or square. [0170] where a shaft has an aperture passing
all or part way through it, as shown in FIGS. 20A through 20E, for
example, then the installation method may include pressing
outwardly from within the aperture. for example, the method may
include pressing a tapered pin into the aperture. [0171] the outer
surface of shaft 222 is not necessarily perpendicular to the head.
For example, FIG. 21 illustrates an embodiment wherein a lower
portion 299 of a shaft 222 is tapered toward groove 224. In this
embodiment, the thickness of shaft 222 increases in the direction
away from head 222. However, if membrane 214 is elastic then
membrane 214 can be pulled over shaft 222 and still contact portion
299 closely enough to be urged into groove 224 as shaft 222 is
deformed. [0172] A through member according to the invention may be
attached to sheet like materials of a wide range of types including
fabrics, membranes, leather, thin metal sheets (e.g. metal foils,
shim stock), plastic sheets, rubberized sheets and the like.
[0173] As shown in FIG. 22, rear sheet 130B of membrane 130 may be
affixed to some or all of thermally-conductive members 114. This
helps to prevent "ballooning" of the heat exchanger, especially
where volume 120 is large. Any suitable means may be provided to
affix rear sheet 130B to thermally-conductive members 114. For
example: [0174] rear sheet 130B may be glued to
thermally-conductive members 114 using a suitable adhesive; [0175]
a piece of material to which rear sheet 130B may be welded may be
affixed in any suitable manner at the inner ends of
thermally-conductive members 114 and rear sheet 130B may be welded
to that piece of material; or [0176] rear sheet 130B may be
mechanically attached to thermally-conductive members 114, for
example: a screw, part of the thermally-conductive member 114 or
the like may pass through an aperture in rear sheet 130B to hold
rear sheet 130B against thermally-conductive member 114; a portion
of rear sheet 130B may be pressed into an aperture on the end of
thermally-conductive member 114; or, a retaining member behind rear
sheet 130B may be held in place by deforming a portion of
thermally-conductive member 114 in a manner similar to that
illustrated in FIGS. 7K and 7L. FIGS. 22A and 22B show one example
of a mechanical means for holding rear sheet 130B to
thermally-conductive member 114.
[0177] In some embodiments of the invention it is desirable that
the outer surface of membrane 130 have different properties than
the surface of membrane 130 which faces into volume 120. For
example, where a heat exchanger is intended to warm or cool a
living subject it may be desirable that the outer surface of
membrane 130 be absorbent to absorb any sweat, dirt or condensation
from the subject's skin. As shown in FIG. 23A, membrane 130 may be
a two-ply membrane having different surface characteristics on its
inner and outer faces.
[0178] In the embodiment of FIG. 23B, membrane 130 is made up of an
inner fluid-impermeable layer 130-1 and an outer absorbent layer
130-2. With this construction, it is unnecessary to make
fluid-impermeable layer 130-1 of a material that is approved for
contact with a subject or other item to be heated or cooled because
only thermally-conductive members and outer absorbent layer 130-2
can come into contact with the subject. As an example, layer 130-2
may comprise SOFTESSE.TM. material available from DuPont.
[0179] Where a membrane has multiple layers, the materials of the
layers may be chosen to have characteristics under compression
and/or elastic characteristics which differ from one layer to the
other. Such membranes may be included to advantage in embodiments
of the invention in which the membrane is compressed between parts
of a thermally-conductive member (as shown, for example, in FIG. 6A
or 13 to 21). In such embodiments of the invention, it can be
desirable for the membrane to include a relatively soft fluid
impermeable layer which can seal well to the thermally-conductive
member. However, a single-ply membrane that is highly compressible
and/or greatly compressed by a thermally-conductive member may take
on a shape which is somewhat distorted in the vicinity of the
thermally-conductive member. By providing a two-ply or two-layer
membrane this problem can be avoided. The membrane can combine a
sealing layer having good properties for sealing with a control
layer. The sealing layer may be highly compressible and relatively
easily stretchable. The control layer may be significantly less
stretchy and less compressible than the sealing layer.
[0180] For example, the sealing layer may comprise a sheet of
suitable plastic material, such as urethane, while the control
layer may comprise a sheet of a woven or unwoven fabric. The fabric
may be significantly less elastic than the sealing layer and, in
some cases may be substantially non-elastic under the expected
conditions of use of the heat exchanger. The sealing layer may be
on the inside of membrane 130 facing into volume 120 in which case
the sealing layer may be welded to a layer making up the back side
of volume 120.
[0181] In some embodiments of the invention the membrane has three
layers, for example, a compressible elastomer sealing layer; a
fabric control layer; and an outer layer of a soft absorbent
material that is approved for skin contact.
[0182] A suitable circulation system may be used to circulate a
heat exchange fluid through the volume 20 of one or more heat
exchangers as described herein. For cooling purposes it is
desirable that the temperature of circulating fluid 65 be greater
than 0.degree. C. to avoid freezing the subject's skin. The desired
temperature of the circulating fluid will depend to some degree on
the application and the portion of the subject's body to be
treated. The desired temperature for cold therapy ranges between
0.degree. C. and 15.degree. C. Water has properties which make it
good for use as a circulating fluid 65.
[0183] It is generally desirable to maintain the pressure of fluid
65 in volume 20 approximately equal to the air pressure surrounding
heat exchanger 10. If the pressure within volume 20 is
significantly smaller than the ambient air pressure then pressure
differences across the walls of volume 20 will tend to collapse
volume 20 although the projecting inside ends 26 of
thermally-conductive members 14 may prevent the walls from complete
collapse. If the pressure within volume 20 is significantly larger
than the ambient air pressure then heat exchanger 10 will tend to
balloon.
[0184] FIG. 24 is a schematic view of a cooling system which
includes a heat exchanger 10 and a fluid circulating system 60.
Circulation system 60 has an insulated reservoir 62 containing a
volume of ice 64. System 60 contains a suitable heat exchange fluid
65, which may be liquid water. System 60 delivers fluid 65 to heat
exchanger 10 through delivery conduit 66 and returns coolant to
reservoir 62 through a return conduit 67.
[0185] A first feed pump 70 upstream from heat exchanger 10
delivers fluid 65 from reservoir 62 to heat exchanger 10. A second
feed pump 72 is located downstream from heat exchanger 10. Second
feed pump 72 draws fluid 65 from heat exchanger 10 and returns the
fluid to reservoir 62. First and second feed pumps 70 and 72 are
balanced so that within volume 20 of heat exchanger 10 the pressure
of fluid 65 is substantially equal to the ambient air pressure.
[0186] One or more bypass valves may be provided to provide better
control over fluid pressure within volume 20. In system 60, an
adjustable bypass valve 74 is connected between the output of first
feed pump 70 and reservoir 62. Bypass valve 74 indirectly regulates
the pressure within volume 20. When bypass valve 74 is opened, a
larger proportion of fluid 65 is returned to reservoir 62 by way of
bypass conduit 75 and the amount of fluid 65 flowing into heat
exchanger 10 is reduced. Bypass valve 74 may be
pressure-operated.
[0187] System 60 has a second bypass valve 76 connected in parallel
with second feed pump 72. When second bypass valve 76 is open,
second feed pump 72 can draw fluid 65 from reservoir 62 by way of
conduit 77. Opening second bypass valve 76 increases pressure at
the input of second feed pump 72 and consequently increases the
pressure within volume 20.
[0188] Many variations of system 60 are possible. Although two
bypass valves are shown in FIG. 24 for maximum flexibility, one
bypass valve connected parallel with either one of pumps 70 or 72
or in parallel with heat exchanger 10 may be sufficient to permit
pressure inside heat exchanger 10 to be maintained within a desired
range. In addition, depending upon the construction of pumps 70 and
72 and the fluid flow properties of the circuit which includes
conduits 66, 67 and heat exchanger 10 it may be possible to
maintain the fluid pressure in volume 20 within the desired range
without the need for bypass valves 74 and 76. Where bypass valves
are provided it is not necessary that they be connected directly to
reservoir 62 as illustrated. Other connections may be provided
which have the result of maintaining pressures upstream and/or
downstream from heat exchanger 10 at values which keep the pressure
within volume 20 at a desired level while maintaining fluid flow
through volume 20.
[0189] In some cases it may be convenient to provide a single
reservoir 62 for providing heat exchange fluid for multiple heat
exchangers 10. In such cases it is best to provide upstream and
downstream pumps 70 and 72 for each heat exchanger 10. In the
alternative, suitable manifolds, such as T-connectors, could be
provided to allow a number of heat exchangers 10 to be connected in
parallel between a single upstream pump system and a single
downstream pump system.
[0190] FIG. 25 illustrates another fluid circulating system 60A. In
system 60A, a first flow regulator 78 comprising a restrictor 80
and a bypass valve 82 is provided between first feed pump 70 and
heat exchanger 10. Bypass valve 82 is connected in parallel with
restrictor 80. When fluid 65 is flowing through flow regulator 78
then a pressure drop across flow regulator 78 depends upon the
fluid flow rate and upon the degree to which bypass valve 82 is
open.
[0191] System 60A has a second flow regulator 79 which includes a
second flow restrictor 84 and a bypass valve 86. Bypass valve 86 is
connected in parallel with restrictor 84.
[0192] In system 60A, bypass valves 82 and 86 are adjustable. The
fluid pressure within volume 20 can be controlled by adjusting one
or both of bypass valves 82 and 86.
[0193] Some alternative embodiments of the invention lack one of
flow regulators 78 and 79. When system 60A is connected to supply
fluid 65 to a plurality of heat exchangers 10 it is preferable to
provide for each heat exchanger 10 at least one adjustable flow
regulator 78 or 79 located where only fluid going to or from that
heat exchanger passes through the flow regulator. This permits the
pressure within each heat exchanger 10 to be individually
regulated. In the alternative, as described above, suitable
manifolds may be provided to split the flow of fluid 65 between a
number of heat exchangers 10 connected in parallel.
[0194] FIG. 26 illustrates another fluid circulating system 60B. In
system 60B the pressure within volume 20 of heat exchanger 10 is
controlled by adjusting the rate of operation of one or both of
upstream and downstream feed pumps 70 and 72. In some embodiments
of the invention a control system simultaneously increases the rate
of operation of feed pump 70 and decreases the rate of operation of
feed pump 72 or vice versa. The rate of operation of pumps 70 and
72 may be controlled by adjusting the rate of rotation of motors
which drive the pumps, by adjusting displacements of the pumps, or
the like.
[0195] In the illustrated embodiment, control is accomplished by
operating a power splitter 88 (illustrated schematically by a
potentiometer). Power splitter 88 can be operated to increase the
speed of a motor driving pump 70 and to decrease the speed of a
motor driving pump 72 or vice versa.
[0196] Systems 60, 60A and 60C may be automatically controlled
using any suitable control system. For example, a controller may be
provided to operate bypass valves and/or control pump speeds or
displacements by way of suitable actuators (not shown) as necessary
to control pressure within volume 20 to stay within a desired
range. Those skilled in the art are familiar with suitable
controllers. The controller may, for example, comprise a suitable
programmed programmable controller or a hardware controller. One or
more pressure sensors and/or flow sensors (not shown) may be
included to provide feedback to the controller.
[0197] Any of cooling systems 60, 60A and 60B could be adapted for
warming by replacing ice 64 with a suitable heating element which
can be operated to raise fluid 65 in reservoir 62 to a desired
temperature. Instead of ice 64, any of systems 60, 60A or 60B could
cool fluid 65 by way of a refrigeration system. However, a
refrigeration system large enough to provide high-rate cooling of a
living person is expensive, consumes a large amount of power and is
not readily portable. Ice has the advantage that melting a block of
ice takes a large amount of heat. A reservoir 62 containing enough
ice to apply high rate cooling to a human subject for a significant
period can be small enough to be readily portable.
[0198] FIGS. 27 through 32C show heat exchangers incorporating
thermally-conductive members 14 or 114 as described above. The heat
exchangers may be used to cool or warm various body parts of a
living subject. FIG. 27 shows a heat exchanger 310 adapted for
cooling or warming the neck of a subject adjacent the subject's
carotid arteries. Such a heat exchanger may be used to cool blood
flowing to the subject's brain. Heat exchanger 310 comprises two
pads 310A and 310B. The pads may be attached around a subject's
neck with fasteners 313A and 313B which may, for example, comprise
complementary hook and loop fasteners such as VELCRO.TM.. A layer
of thermally-conductive gel may be provided on the pad to improve
heat transfer between the subject's skin and thermally-conductive
members 114. Cooling fluid may be introduced through an inlet port
322. The cooling fluid circulates through both of pads 310A and
310B before exiting at outlet port 323. A tube 311 carries fluid
from pad 310A to pad 310B and a return tube 312 returns fluid from
pad 310B to pad 310A.
[0199] FIGS. 28A, 28B and 28C show a heat exchanger 310 like that
of FIG. 27 in position on the neck of a subject.
[0200] As shown in FIGS. 29A through 30C, additional heat exchanger
pads may be connected in series with heat exchanger 310 to cool or
warm a larger area of the subject. FIGS. 29A, 29B and 29C show a
system 318 which includes a pad 310C configured to be applied over
a subject's face. Pad 310C receives fluid from pad 310A through
tube 311A and returns fluid to pad 310B through tube 312A. Pad 310C
is held in place by a head strap 314 and a chin strap 315.
[0201] FIGS. 30A, 30B and 30C show a head cooling and/or warming
system 320 which includes a scalp pad 310D in addition to the pads
310A, 310B and 310C of the system of FIGS. 29A through 29C. Scalp
pad 310D is configured to conform substantially with the scalp of a
subject. In the illustrated embodiment, scalp pad 310D receives
fluid from face pad 310C by way of tube 311B and returns fluid to
face pad 310C by way of tube 312B.
[0202] FIG. 31 illustrates a system 340 for cooling or warming
multiple regions of a subject. System 340 includes a head cooling
and/or warming system 320 as shown in FIGS. 30A through 30C, a
torso cooling and/or warming system 342 and a thigh cooling and/or
warming system 344. Each of systems 320, 342 and 344 are connected
to a source 60 of a cooled (or warmed) fluid. The rate of flow of
fluid through each of systems 320, 342 and 344 may be independently
regulated. In some embodiments of the invention, a controller
associated with source 60 regulates the rate of fluid flow through
systems 320, 342 and 344 in response to measurements of the
subject's core temperature or equivalent measurements and a target
value for the subject's core temperature.
[0203] FIG. 32A illustrates a possible arrangement of fluid
passages in head cooling and/or warming system 320. FIG. 32B
illustrates a possible arrangement of fluid passages in torso
cooling and/or warming system 342. FIG. 32C illustrates a possible
arrangement of fluid passages in thigh cooling and/or warming
system 344. Thermally-conductive members 114 have been omitted from
FIGS. 32A through 32C for clarity.
[0204] As noted above, heat exchangers according to alternative
embodiments of the invention may be applied to heating or cooling
objects of diverse types. For example, FIG. 33A shows a heat
exchanger 10 being used to cool an electric motor 52. Bases 29 of
thermally-conductive members 14 contact the curved outer surface 53
of motor 52. FIG. 33B shows a heat exchanger 10 being applied to
cool a compressor 54 having an outer housing 55 which has a profile
having compound curvature. Bases 29 contact the surface of housing
55. Compressors having compound curves are frequently used in
refrigeration and air conditioning systems. FIG. 33C and 33D show a
heat exchanger 10 being applied to cool a pipe 56. Bases 29 contact
an outer cylindrical surface 57 of pipe 56. Pipe 56 could be an
exhaust pipe, for example.
[0205] Bases 29 or 129 of thermally-conductive members of heat
exchangers as described herein may be shaped to better conform with
a surface of an object to be warmed or cooled. For example, FIG.
33E shows a heat exchanger in which bases 129 of
thermally-conductive members 114 are machined or otherwise shaped
to provide concave faces 129A. Faces 129A each have a radius of
curvature to match that of the cylindrical surface of a housing 55
of an object to be heated or cooled. On other embodiments (not
shown), thermally-conductive members 14 or 114 may have faces
shaped to provide convex surfaces of surfaces having more complex
shapes to match the profile of a surface of an object to be cooled
or heated. In some cases, ends of thermally-conductive members 14
or 114 may be affixed, for example, with bolts or studs, to a
surface of an object to be cooled or heated.
[0206] An object to be heated or cooled may be specially configured
to match a heat exchanger according to this invention. FIG. 33F
shows an object to be cooled which has sockets 55A in an outer
housing 55. A heat exchanger has thermally-conductive members 114
having bases 129 with ends 129B inserted into and shaped to conform
with sockets 55A. A suitable thermally-conductive paste may be used
to enhance thermal contact between thermally-conductive members 114
and housing 55. FIG. 33G shows thermally-conductive members having
ends shaped in various ways.
[0207] FIG. 34 illustrates schematically a heat exchanger 58 being
used to cool an object 59 having a temperature high enough that it
could cause degradation of material 30. Heat exchanger 58 is
similar to heat exchanger 10 except that bases 29 are elongated so
that they contact object 59 at a location spaced away from material
30. A heat shield 360 is provided between object 59 and material
30. Thermally-conductive members 14 pass through the heat shield.
Each of thermally-conductive members 14 extends through a thermally
insulating sleeve 59A. Sleeves 59A protect material 30 from
becoming overheated through contact with members 14. Shield 360
protects material 30 from heat radiated by object 59.
[0208] Heat exchangers may also be used to transfer heat between
fluids and/or between solid objects. FIG. 35A shows a heat
exchanger 61 comprising a membrane of a material 30 penetrated by
thermally-conductive members 62. Members 62 have bodies 29 on both
sides of material 30. As shown in FIG. 35B, bodies 29 can
optionally comprise fins, pins or other thermally-conductive
elements disposed to provide improved thermal contact between the
body 29 and a surrounding fluid. The heat exchanger 61A illustrated
in FIG. 35B has pins 32 projecting from each body 29. Bodies 29 are
larger in area than the central portions of members 14 which pass
through material 30. The edges of the bodies press against the
membrane to seal any gap between the member and the membrane so
that fluid will not leak from one side to the other.
[0209] FIGS. 36A through 37F show a pad 510 according to one
embodiment of the invention. Pad 510 has an inlet 512 for receiving
a heat exchange fluid 513, a path 514 along which heat exchange
fluid 513 can flow, and an outlet 516. In some embodiments, heat
exchange fluid 513 is recirculated along a fluidic circuit
extending between a temperature controller and one or more pads
510. For example, pad 510 may be used in one of the systems for
heating or cooling a body disclosed in PCT patent application No.
PCT/CA2004/001660.
[0210] Path 514 of pad 510 is defined in a chamber 518 between a
back sheet 520 and a front sheet 522 that are bonded together along
connection lines 523. Connection lines 523 comprise locations along
which back sheet 520 and front sheet 522 are affixed to one another
by welding, a suitable adhesive, or other suitable affixation
means. Thermally-conductive members 524 are disposed along path
514. Each thermally-conductive member 524 penetrates and is sealed
to front sheet 522 to prevent heat exchange fluid 513 from leaking
around thermally-conductive members 524.
[0211] Each thermally-conductive member 524 has an outer face 524A
on a front face of pad 510 and an inner face 524B on a part of
member 524 that projects into chamber 518. Inner faces 524B of
thermally-conductive members 524 are in contact with heat exchange
fluid 513. Thermally-conductive members 524 may have, for example,
any of the constructions described in the above-noted PCT
application.
[0212] Rear sheet 520 is formed to provide a cup 530 coinciding
with each thermally-conductive member 524. As seen best in FIGS.
37B and 37C, the cross-sectional area of path 514 alternates
between cups 530 in which the cross-sectional area is relatively
large and constricted areas 532 between thermally-conductive
members in which the cross-sectional area of path 514 is relatively
small. In embodiments illustrated by FIG. 37B, the clearance 535
between inner face 524B of the thermally-conductive member 524 and
rear sheet 520 is greater than the clearance between rear sheet 520
and front sheet 522 in constricted area 532. In the embodiments
illustrated by FIG. 37C, the width of path 514 is greater in
portions of path 514 adjacent a thermally-conductive member 524
than it is in its constricted portions 532.
[0213] In some preferred embodiments front sheet 522 and rear sheet
520 are very flexible fluid-impermeable sheets such as thin sheets
of polyether thermoplastic polyurethane. This material has a
temperature range from -60 C to 140 C. Front sheet 522 and rear
sheet 520 may also be made of other suitable materials, such as
urethane, polyurethane, polyvinylchloride (PVC), rubber, silicone,
or the like. Various materials suitable for use as front sheet 522
and rear sheet 520 are described in the above-noted PCT
application. The material of rear sheet 520 is preferably somewhat
elastic. Urethane having a thickness of approximately 0.015 inches
has been found to be a satisfactory material to use for rear sheet
520.
[0214] For some applications, the thermal characteristics of the
materials are important. For example, some polyvinylchloride
materials become quite brittle at temperatures below 5.degree. C.
Ethylvinylacetate can also become undesirably rigid at low
temperatures. Such materials would not be optimum choices for front
sheet 522 and rear sheet 520 in applications where a pad 510 is
operated at lower temperatures.
[0215] Fluid flowing along path 514 encounters a pattern of
alternating constrictions 532 and enlarged areas corresponding to
cups 530. Although the inventors do not wish to be bound by any
particular theory of operation, this alternating pattern of areas
of greater and lesser cross-sectional area is thought to help to
prevent chamber 518 from becoming overly inflated and overly rigid
as heat exchange fluid 513 flows through pad 510. This pattern may
also assist heat transfer between thermally-conductive members 524
and heat exchange fluid 513.
[0216] In some embodiments of the invention the cross-sectional
area of path 514 in constricted areas 532 is about 50% or less, (in
some embodiments 25% or less, or even 10% or less) of the
cross-sectional area of path 514 in the vicinity of a
thermally-conductive member 524. In all such embodiments, the
cross-sectional area in constricted areas 532 can be said to be
"substantially less" than the cross sectional areas adjacent
thermally-conductive members 524.
[0217] The configuration of path 514 can be adjusted by altering
the manner in which rear sheet 520 is formed. For example, making
cups 530 deeper increases the cross-sectional areas of path 514 in
its parts adjacent to thermally-conductive members 524. The
configuration of path 514 can also be adjusted by altering the
paths of connecting lines 523. For example, the cross-sectional
area of constricted portions 532 can be made smaller by making the
opposing connecting lines 523 closer to one another. Similarly, the
cross-sectional area of constricted portions 532 can be made larger
by making the opposing connecting lines 523 farther apart from one
another.
[0218] FIG. 37F shows an alternative embodiment of the invention
wherein connecting lines 523 are straight and constricted portions
532 are defined, in part, between opposing spot connections 523A
and 523B. FIG. 37G shows a pad 510A which is similar to pad 510. In
pad 510A the pattern of cupped areas 530 and back sheet 520 and
connecting lines 523 and spot connections 523A and 523B is such
that path 514 follows a zig-zag course.
[0219] FIGS. 38A to 38C illustrate the fact that a pad according to
the invention can be very flexible and can be made to conform with
a surface of a body such as the cylindrical body 540. Body 540 can
be anything that it is desired to heat or cool with a pad 510
according to the invention. Body 540 may be a portion of a body of
a living being, such as a human or animal, or may be a part of a
device, machine or the like.
[0220] FIGS. 39A through 39C show thermal reservoirs 550A, 550B and
550C (collectively thermal reservoirs 550) as provided by another
aspect of the invention. Each thermal reservoir 550 comprises a
bladder 552 containing a heat storage material, which is preferably
a liquid, such as water, that has a phase transition (e.g.
freezing/melting) at a temperature in a range of interest. The heat
storage material can either take in or give out heat.
[0221] A number of thermally-conductive members 524 penetrate the
material of bladder 552 on at least one face thereof.
Thermally-conductive members 524 provide paths of very high thermal
conductivity between their outer faces 524A and the heat storage
material contained within bladder 552. Thermal reservoirs 550 may
be used as ice packs, or may be used to warm or cool a heat
exchange fluid, or the like.
[0222] Each bladder 552 is made of a suitable material (which may
be a material of the same type as used for the pads 510 described
above). While bladders 552 are preferably flexible, in some
embodiments of the invention, bladders 552 are of a stiffer
material, such as a plastic, that holds its shape.
[0223] Thermally-conductive members 524 may be arranged in any
suitable patterns on thermal reservoirs 550. Thermally-conductive
members 524 may be disposed on one or more sides of a thermal
reservoir 550.
[0224] FIGS. 39D, 39E and 39F show a thermal reservoir 555 that
combines structural features of a pad 556 that is like pad 510 of
FIGS. 36A and 36B, and a bladder 557 filled with a heat storage
material 558. Bladder 557 may, for example, be filled with water.
The water may be frozen. A heat exchange fluid may subsequently be
cooled by circulating it through pad 556.
[0225] As shown in FIGS. 39E and 39F the front sheet 522 of pad 556
forms a portion of one wall of bladder 557. Faces 524A of
thermally- conductive members 524 are in contact with heat storage
material 558. Faces 524B of thermally-conductive members 524 are in
contact with heat exchange fluid 513 in pad 556. As heat exchange
fluid 513 is circulated through pad 556 it is either warmed or
cooled. Whether heat exchange fluid is warmed or cooled depends
upon the relative temperatures of the heat storage material 558 and
the incoming heat exchange fluid 513.
[0226] In the embodiment illustrated in FIGS. 39D to 39F, bladder
557 is formed by affixing a sheet 559 to pad 556 in any suitable
way. For example, sheet 559 may be welded to pad 556 to provide
fluid-tight bladder 557. In the illustrated embodiment, sheet 559
has been formed (for example by vacuum forming) to allow a
relatively large volume of heat storage material 558 to be
contained in bladder 557 without distortion of front sheet 522 of
pad 556.
[0227] One or more drain ports (not shown) may optionally be
provided to allow heat storage material 558 to be added or changed.
In some embodiments, a hole is punched through the walls of bladder
557. Heat storage fluid 558 is introduced through the punched hole.
The hole is then sealed by a rivet and washer as described in the
appended PCT application.
[0228] FIGS. 39G and 39H show a thermal reservoir according to a
further embodiment of the invention in which bladder 557 is roughly
lenticular in cross section when filled with thermal storage
material 558.
[0229] FIGS. 40A to 40E show systems for heating or cooling a
living being (a "subject") or an object which incorporate one or
more heat exchange pads, as described above and/or one or more
thermal reservoirs as described above. FIG. 40A shows a system 560
that has a pad 510 connected in a fluid circuit 562 through which a
heat exchange fluid 513 is circulated by a pump 564. Outer faces
524A of the thermally-conductive members 524 of pad 510 are in
thermal contact with an ice pack 565. System 560 includes a heat
exchanger 566, which could comprise another pad 510, a pad as
described in PCT patent application No. PCT/CA2004/001660, or some
other heat exchanger. Heat exchanger 566 is in contact with a body
to be cooled. For example, heat exchanger 566 may be in contact
with a portion of a human or animal body to be cooled.
[0230] Fluid 513 passes out of pad 510 at outlet 516, along tube
567A to heat exchanger 566. Fluid 513 returns to pad 510 by way of
tube 567B, pump 564 and tube 567C. A controller 568 (which may
comprise any suitable programmable controller or control circuitry,
for example) senses a temperature of heat exchange fluid 513
circulating past a temperature sensor 569 and controls pump 564 to
adjust a rate of flow of the heat exchange fluid 513 to maintain a
desired temperature. Additional temperature sensors (not shown) may
be provided in other parts of fluid circuit 562 (for example at
heat exchanger 566) to provide additional inputs to controller
568.
[0231] The provision of a pad 510 equipped with thermally-
conductive members 524 helps to facilitate transfer of heat from
circulating heat exchange fluid 513 into ice pack 565. Apparatus
560 could use a pad of one of the types described in PCT patent
application No. PCT/CA2004/001660 in place of pad 510.
[0232] FIG. 40B shows a system 570 for heating or cooling that is
similar to system 560 of FIG. 40A but differs in two respects. In
system 570 temperature sensor 569 senses the temperature of heat
exchange fluid 513 returning to pad 510 from heat exchanger 566
instead of the temperature of heat exchange fluid being carried
from pad 510 to heat exchanger 566. Also, system 570 has a thermal
reservoir 555 which may be like that shown in FIGS. 39D, 39E and
39F, for example. Thermally-conductive members 524 of pad 10 are in
contact with thermally-conductive members 524 of thermal reservoir
555.
[0233] In some embodiments of the invention, thermally-conductive
members 524 are arranged in complementary patterns on pad 510 and
thermal reservoir 555. In some embodiments of the invention, the
faces of thermally-conductive members 524 of pad 510 have shapes
that are complementary to the shapes of the faces that they contact
of thermally-conductive members 524 of thermal reservoir 555. For
example, the faces of both sets of thermally-conductive members may
be flat so that a large area of contact is made between the
thermally-conductive members 524 of pad 510 and the
thermally-conductive members 524 of thermal reservoir 555. In some
embodiments, magnets or other means may be provided to urge the
thermally-conductive members 524 of pad 510 into contact with the
thermally-conductive members 524 of thermal reservoir 555 to ensure
maximum surface area contact between the thermally-conductive
members 524 of pad 510 and the thermally-conductive members of
thermal reservoir 555. For example, a small rare-earth magnet may
be embedded in a thermally-conductive member 524 of pad 510 and
another small magnet of opposite orientation or a piece of
ferromagnetic material may be embedded in the corresponding
thermally-conductive member of heat reservoir 555.
[0234] FIG. 40C shows a cooling system 572 which is similar to
system 560 except for the locations in circuit 562 of pump 564 and
temperature sensor 569 and the arrangement of pad 510. System 572
uses a larger pad 510 than is shown in system 560. In system 572,
pad 510 is wrapped around ice pack 565. Another feature of system
572 is that heat exchanger 566 is expressly indicated as being
equipped with thermally- conductive members 524.
[0235] FIG. 40D shows a heating or cooling system 574 in which heat
exchange fluid circulating in pad 510 is in contact with a thermal
reservoir 575 having thermally-conductive members 524 on multiple
faces. Thermal reservoir 575 has a first group 577 of
thermally-conductive members 524 on its top surface and a second
group 578 of thermally-conductive members 524 on its bottom
surface. Thermally-conductive members of pad 510 are in contact
with both sets of thermally-conductive members of thermal reservoir
575 to enable a relatively high rate of heat transfer between heat
exchange fluid 513 circulating in pad 510 and the heat exchange
material 558 in thermal reservoir 575.
[0236] FIG. 40E shows a system 580 for warming or cooling a person,
animal or object having an integrated thermal reservoir 555 like
that shown in FIGS. 39D through 39F. A heat exchange fluid 513 is
heated or cooled as it circulates through integrated thermal
reservoir 555. The fluid passes through a heat exchanger 566 which
is in thermal contact with a person, animal or object to be heated
or cooled.
[0237] In alternative systems like those of FIGS. 40A to 40E, a pad
510 containing a heat exchange fluid 513 could be immersed in or in
contact with a liquid that acts as a thermal reservoir. The liquid
of the thermal reservoir may be at a temperature suitable to take
up or give heat to the heat exchange fluid 513 circulating in the
pad 510. for example, in some embodiments, the liquid of the
thermal reservoir may comprise a volume of cold water or ice
water.
[0238] Another embodiment of the invention is illustrated by FIG.
41 which shows a system 590 for cooling a person or object. System
590 comprises a source 592 of compressed heat exchange fluid 593,
which may comprise compressed air, for example. An air compressor
(not shown) may be provided to fill source 592 with compressed air.
Heat exchange fluid is allowed to pass through a control valve 594
into an expansion chamber 596. Expansion of heat exchange fluid 593
causes heat exchange fluid 593 to become cooler. The cooled heat
exchange fluid 593 passes from expansion chamber 596 into a heat
exchanger 598. Heat exchanger 598 is in contact with a person or
animal or object to be cooled. After passing through heat exchanger
598, the heat exchange fluid may be vented as indicated at 599.
[0239] Heat exchanger 598 may comprise a pad (for example a pad
510) as described herein or a heat exchanger as described in PCT
patent application No. PCT/CA2004/001660. The heat exchanger 598 of
FIG. 41 has thermally-conductive members 524 that are in contact
with heat exchange fluid 593 inside heat exchanger 598 and extend
through a wall of heat exchange 598 to contact a body to be
cooled.
[0240] A controller 600, which may comprise a programmable
controller or another suitable control circuit or mechanism
operates control valve 594 in response to a temperature sensed at
temperature sensor 602.
[0241] System 590 could be used in any of many ways including to
cool a subject's body in a case where cooling is required for some
medical purpose or to provide comfort for a person in a hot
environment, for example.
[0242] In lieu of, or in addition to an expansion chamber, system
590 could include a suitable "metering" device to decrease the
pressure of the heat exchange fluid without the use of an expansion
chamber. For example, system 590 may comprise an expansion valve,
capillary line, etc. Such devices are known to those skilled in the
fields of air conditioning and refrigeration.
[0243] FIGS. 42A, 42B and 42C are views of a pad 610 according to
an alternative embodiment of the invention. Pad 610 is
substantially similar to pad 510 shown in FIG. 37A except that, in
addition to thermally-conductive members 524 passing through front
sheet 522, pad 610 includes additional thermally-conductive members
624 that pass through rear sheet 520. Pad 610 can exchange heat
with thermal reservoirs or other heat sources or sinks on both of
its sides. For example, when used in a system like system 560 or
570 (see FIGS. 40A and 40B) a pad 610 could be in thermal contact
with ice packs, or thermal reservoirs 555 on both sides of the pad
610. In the alternative, pad 610 may be immersed in a bath of
liquid, in which case, the addition of thermally-conductive members
624 provides for a higher rate of heat transfer between the liquid
and a heat exchange fluid 513 circulating in the pad 610.
[0244] Where a component (e.g. a member, pump, valve, sensor,
controller, assembly, element, device, circuit, etc.) is referred
to above, unless otherwise indicated, reference to that component
(including a reference to a "means") should be interpreted as
including as equivalents of that component any component which
performs the function of the described component (i.e., that is
functionally equivalent), including components which are not
structurally equivalent to the disclosed structure which performs
the function in the illustrated exemplary embodiments of the
invention.
[0245] As will be apparent to those skilled in the art in the light
of the foregoing disclosure, many alterations and modifications are
possible in the practice of this invention without departing from
the spirit or scope thereof. For example: [0246]
Thermally-conductive members 14 or 114 may have any suitable shapes
and arrangements. Those illustrated herein are but examples. [0247]
Flexible material 30 may have different compositions in different
parts of a heat exchanger according to the invention. Different
suitable flexible materials 30 may be used for material 30 in
different parts of a heat exchanger. [0248] A heat exchanger
according to the invention is not necessarily rectangular or
parallel-sided. A heat exchanger according to the invention could
have other shapes. Heat exchangers according to some embodiments of
the invention are elongated and have fluid inlets and fluid outlets
located in areas at opposed ends of a long axis. [0249] The
arrangements of heat exchangers shown in the Figures could be
applied to warm a subject instead of to cool a subject.
* * * * *