Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a heat exchanging garment useful for
heating or cooling the human body in circumstances where the body's natural
mechanisms of temperature regulation are impeded or overwhelmed. Heat
transfer garments may be used for heating all parts of the body in
environments
where passively insulating clothing provides insufficient protection, for
example in
cold water diving, or in outdoor activities in winter conditions. Such
garments may
also be used to provide cooling for persons wearing clothing which impedes
cooling by the evaporation of perspiration, for example persons using vapour-
impermeable suits to protect them against toxic chemicals.
BACKGROUND OF THE INVENTION
In the past, several garments to provide cooling have been developed.
These have included systems which pass air over the body, garments which
incorporate ice or solid carbon dioxide in pockets, and garments which cool by
circulating a chilled liquid through passages in the garment. United States
Patent
No. 3,430,688 describes a circulating liquid garment to be used in cooling the
user.
Circulating liquid garments have also been used to heat the body. United
States
Patent No. 3,744,053 describes a circulating liquid garment to be used for
warming
the user.
JENNINGS United States Patent No. 3,289,748 provides a heat transfer
garment having heat transfer tubes which are distributed in a serpentine or
meandering pattern so that the distribution of the tubing over the body is in
approximate proportion to the local body mass to thereby provide heat removal
capacity commensurate with metabolic heat generation capability. The spacing
between the tubes and the shapes of the tubes along their lengths vary to
provide
the desired heat removal capability. A drawback to this arrangement is that
the
tubes are almost straight in regions, such as the waist, where maximum
curvature
would be desirable to permit the user to bend over without discomfort.
Furthermore, the arrangement is not readily susceptible to mass production
because of the different shapes of the various tubes required. Thus, the tubes
must be positioned and shaped by hand and head in position on a fishnet-like
cloth by individual, hand applied tacks.
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BURTON United States Patent No. 3,425,486 illustrates a heat transfer
garment having heat transfer tubes which are also distributed in a serpentine
or
meandering pattern similar to the JENNINGS patent. However, BURTON places
little importance on the spacing and the shape of the tubes, but states that
the
S tubes should avoid regions, such as at the elbows and behind the knees,
where
there is likely to be substantial bending. The essence of the BURTON patent is
to provide tube locating means in the form of tunnels so that as the garment
body
stretches with movement of the wearer, the tubes will be able to slide and or
twist
within the tunnels so as to, in turn, reduce any restriction of movement. Like
JENNINGS, the spacing between the tubes and the shapes of the tubes along
their lengths vary to provide the desired heat removal capability. Thus, the
BURTON arrangement suffers from the same disadvantages as the JENNINGS
arrangement but includes additional complexity in terms of the cost and
attachment of the tube locating tunnels to the garment.
Although prior designs of liquid circulating heat transfer garments have
been shown capable of transferring heat at significant rates, these prior
designs
have proven to be uncomfortable to wear, either because such prior garments
have covered too small a portion of the body's area for the heat transferred,
or
because of excessive bulk and restriction of the user's movements. Prior
designs
of liquid circulating heat transfer garments have also been subject to flow
blockages due to pinching~of the liquid passages, causing unreliable
operation.
Prior designs of such garments have also been costly to manufacture.
SUMMARY OF THE INVENTION
The present invention seeks to provide a heat transfer garment which
provides effective heating or cooling over sufficient body area to prevent
thermal
discomfort to the user, which does not unduly restrict movement of the user
and
is thus more comfortable than prior designs, which is not prone to flow
blockage
or leakage upon flexure of the body and thus operates reliably, and which may
be
manufactured at a reasonable cost, thus allowing its use in more applications.
This can be achieved by providing a plurality of lengths of flexible, heat
transfer tubes which extend longitudinally of the garment or portion thereof,
with
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the lengths of tube being substantially equally spaced apart and being secured
to
the garment so as to form a generally sinusoidal shape along a major portion
of
the length of the tubes and with adjacent sections of tubes being
substantially
in-phase with one another.
Thus, the present invention is generally defined as a heat transfer garment
for modulating the heat flow to or from the body of the user, the garment
comprising an assembly of fabric constructed to conform substantially to the
contours of a body portion over which it is to be used, a plurality of lengths
of
flexible tubes secured to one surface of the fabric so as to extend along the
length
of the fabric, the lengths of tube being substantially uniformly spaced apart
transversely of the fabric and each length being substantially sinusoidal in
shape
along a major portion of its length, and adjacent lengths being substantially
in-
phase with one another, means for supplying heat transfer liquid to one end of
each the tube, and means for receiving heat transfer liquid discharged from
the
opposite end of the tubes.
In this manner, heat is distributed substantially uniformly over the portion
of the body covered by the garment. The sinusoidal shape readily accommodates
bending without discomfort to the user so that it is not necessary to avoid
the
provision of tubes at bend points or axes while also avoiding of sharp bends
in the
tubes which could block flow. Further, since the tubes are arranged in a
uniform
pattern on the garment, the garments may be relatively easily mass produced.
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BRIEF DESCRIP'CION OF THE DRAWINGS
These and other features of the invention will become more apparent from
the following description in which reference is made to the appended drawings
wherein:
FIGURE 1 is a front view of heat transfer garment in the form of a shirt
according to a preferred embodiment of the present invention;
FIGURE 2 is a back view of the heat transfer garments in the form of a pair of
trousers according to a preferred embodiment of the present invention;
FIGURE 3 is an enlarged fragmentary view showing a portion of the garment in
detail;
FIGURE 4 is a detail view showing a portion of the garment where two tubes are
gathered to a single tube;
FIGURE 5 is a detail view showing a method of tube attachment to the
supporting cloth; and
FIGURE 6 is a graph illustrating measured heat transfer performance of a
medium sized sleeveless shirt constructed in accordance with the present
invention.
DESCRIPTION OF PREFERRED EMBODIMENT
FIGURES 1 and 2 illustrate two articles of heat transfer clothing including
a long-sleeved shirt 10 and trousers 12. Although these two are shown, it is
understood that any other type of heat transfer clothing may be constructed
according to this invention, such as coveralls, gloves, mitts, socks, shoes or
boots,
vests, hoods or caps. .
Each section of both articles includes a plurality of lengths of heat transfer
tubes 14 which extend longitudinally of the section of the garment. In the
case
of the shirt 10, "section" means the torso portion and the sleeves. In the
case of
the trousers 12, "section" means the leg portions optionally extending up into
the
lower torso portion. The lengths are spaced apart substantially equally in a
transverse or circumferential direction and each length is secured to the
garment
so as to form a substantially sinusoidal shape with adjacent lengths being
"in-phase" with one another. The axes of the sinusoidal shapes may diverge of
CA 02015621 1999-09-17
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converge slightly in the sleeves and legs of the garment without departing
from the
spirit of the invention. The term "in-phase" means that the centres of
curvature
of the curved portions of the lengths of tube are circumferentially aligned,
as best
shown in FIGURE 3. It will be seen that this arrangement will provide uniform
stresses in both longitudinal and transverse directions and the weight of the
garment will be substantially uniform in all regions. This will be reflected
as more
comfortable to the user. Further, when the garment is folded as a result of
bending of the body, all of the tubes will bend at essentially the same point
along
their respective lengths and this again will be more comfortable to the user.
Still
further, the heat transfer to or from the body will be uniform and more
comfortable as compared to tubes lengths concentrated in predetermined regions
as suggested by the prior art.
In the illustrated embodiment, a single tube provides several lengths in
which a portion of the tube extends in one longitudinal direction, turns back
on
itself and then extends in the opposite direction and so on. It will be
understood
that the heat transfer tubes may be connected in parallel to a source of
suitable
heat transfer fluid so as to provide more uniform heat transfer distribution
to the
skin of the user. The present invention contemplates all such obvious ways of
arranging the tubes.
In use, heat exchanging liquid is injected through an inlet tether tube 16
to liquid inlet tubes 20 and 22 in the shirt 10 and trousers 12, respectively.
In the
shirt, the heat exchanging liquid passes from inlet tube 20 through tee-like
fittings
24, illustrated in FIGURE 4, and into an inlet manifold tube 26 which feeds a
plurality of individual tubes 28. The heat exchanging liquid which passes
through
tubes 28 exchange heat with the skin of the user, thus cooling or heating the
user's
trunk and arms. Tubes 28 discharge into a discharge manifold tube 30, through
tee-like fittings 24, which in turn discharges into outlet tube 31 and finally
to an
outlet tether tube 32. It will be noted that manifolds 2G and 30 are in the
form
of a collar of the shirt. As shown in FIGURE 1, each individual tube 28
provides
four lengths of tube extending along the length of the garment. In a similar
fashion, the trousers are formed with inlet and outlet tubes respectively
connected
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to inlet and outlet manifold tubes interconnected by parallel individual heat
exchange tubes.
Outlet tether tube 32 is connected to a heat exchanger 40 and pump 42,
as shown in FIGURE 1, before returning to the heat transfer garment through
inlet tether tube 16. When used in cooling, the heat exchanger may be an ice
bath, a device cooled with solid carbon dioxide, or a mechanical or
thermoelectric
refrigeration unit. When used in heating, the heat exchanger may be an
electric
or a fuel burning heater.
A preferred method of affixing the heat transfer tubes to the supporting
cloth 50 is shown in FIGURE 5. The method employs zig-zag stitching using a
first thread 52 on the tube side of the cloth which interlocks with a second
thread
54 on the opposite side of the cloth so.as to hold the tube in place along its
length. This method of stitching may be done by machine, thus eliminating the
manual stitching used in previous garments and reducing the cost of the
garment.
An advantage of attaching the tube to the cloth along its length is that the
tube
is less susceptible to kinking when supported continuously by the cloth. Other
methods of affixing the tubing to the supporting cloth may also be employed.
Such alternate methods include glues, and solvent welding or thermal welding
for
cloth of certain synthetic materials, such as polypropylene.
Garments constructed according to the invention may be worn with the
tubes directly against the skin, or, for more comfort, with the tubes disposed
outwardly so that the tubes are separated from the skin by the supporting
cloth.
Alternately, light undergarments may also be worn under the heat transfer
garments. A second layer of cloth may also be incorporated into the heat
transfer
garment so that the heat transfer tubes are covered on both sides. It has been
found that more heat is transferred when the tubes are placed directly on the
skin,
than when a layer of cloth separates the tubes from the skin. Heat transfer is
also
aided if the tubes are urged gently against the skin in a resilient manner.
The in-phase sinusoidal paths taken by the heat transfer tubes, as
illustrated in FIGURE 3, is important in effecting close contact between the
skin
and heat transfer tubes continuously along the length of the tubes. The
support
cloth is preferably a stretch knit material, cut and sewn to fit tightly to
the user
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and placed so that the direction of greatest stretch of the cloth is around
the
circumference of the body. Such stretch knit materials will shrink in the
axial
direction, as indicated by the arrow A, when stretched in the circumferential
direction, as indicated by the arrow B.
The heat transfer tubing will not easily be extended or compressed along
its own axis. Accordingly, an important advantage of the sinusoidal shape of
the
heat transfer tubes is to allow the tube and cloth assembly to stretch
circumferentially while maintaining close contact with the body as it moves.
The
sinusoidal pattern permits the tube and cloth assembly to shrink in the axial
direction as it stretches circumferentially without causing the tubing to
buckle
away from the body in a series of bumps.
A further advantage of the in-phase sinusoidal arrangement of tubes is that
the spacing between adjacent tube paths does not vary greatly along the length
of
the tube. This factor maximises the effectiveness of the tube used in
transferring
heat. It has been have found that in cooling use, the temperature of the skin
is
coldest directly under the heat transfer tube and is warmest at points most
distant
from the tubes. Conversely, in heating, the skin temperature is highest
directly
under the tube and lowest at points most distant from the tubes. The ability
of
the body to transfer heat to or from the tube is limited by the thermal
conductivity
of the skin and flesh and by the blood supply in the affected area. Because of
this, it is apparent that more heat will be exchanged with a given length of
tubing,
if that tubing is located in a region little affected by adjacent tubes. The
in-phase
sinusoidal tube pattern used by heat transfer garments of this invention thus
maximises heat transfer per unit length of tubing, while providing a garment
which
remains close to the body in a comfortable manner. It has also been found that
the approximate spacing between adjacent sinusoidal tube paths may be varied
throughout the garment to adjust the effectiveness of the garment in
transferring
heat to suit the circumstances, or to suit that portion of the body covered.
FIGURE 6 shows the measured heat transfer performance of one such
garment, a medium-sized sleeveless shirt. In this garment, heat transfer tubes
of
flexible polyvinyl chloride were used, each tube having an outside diameter of
1/8
inch, an inside diameter of 1/16 inch and a length of approximately 16 feet.
In
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FIGURE 6, the heat transfer can be seen to be negative, indicating body
cooling,
at average heat transfer liquid temperatures below 34°C, and positive,
indicating
body heating, at liquid temperatures above 34°C.
While the forms of the apparatus herein described constitute preferred
embodiments of the invention, it is to be understood that the invention is not
limited to these precise forms of apparatus, and that changes may be made
therein without departing from the scope of the invention which is defined in
the
appended claims.
