Note: Descriptions are shown in the official language in which they were submitted.
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~ CA 02543778 2006-04-26
1
HEATING CUSHION AND DEVICE COMPRISING SUCH A CUSHION
Field of the invention
The invention relates to thermal cushions and to
their use.
State of the art
The hospital sector and ambulatory medicine are major
users of thermal cushions, in particular for external thermal
regulation and in order to relieve pain or in various
therapies such as for example cryotherapy.
Indeed, it is known that the application of cold can
relieve pain (headaches, migraine, toothaches, muscular or
inflammatory pains, etc.) or encourage the resorption of
hematomas, edemas and the healing of accidental or surgical
wounds.
US 3,545,230 proposes a coolant cushion that uses the
latent heat of fusion of a solid substance. During this fusion
phase, the temperature remains constant. The cushion comprises
a layer of insoluble and hydrophilic gel in a sealed and
flexible envelope. An inert and flexible substrate (for
example fibres or a fabric), immersed in the gel, serves to
strengthen the mechanical resistance of the cushion and allows
it to take any geometrical form. To give the cushion
sufficient flexibility, several layers of gel of very small
thickness (barely a few millimetres) are superposed on each
other and a flexible and inert film is inserted between the
layers of gel. This known cushion has the drawback of being
difficult and expensive to produce, its performances are weak
and its applications limited.
In document EP 0 123 949, the cryogenic substance of
the cushion comprises pieces of gel with a particular
structure having an elasticity that is comparable to that of
rubber and which do not stick together at the temperature of
CA 02543778 2006-04-26
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cold production. The motion of the pieces of gel relative to
each other in the cushion gives the latter the desired
flexibility. These known cushions nevertheless have the
drawback of requiring an expensive gel and their manufacture
is delicate and costly.
United States patent US 3,885,403 suggests to use for
the cryogenic substance a gel containing a high proportion of
an agent that lowers the freezing point below the normal
temperature of use. Glycerine and propylene glycol are
proposed for the agent that lowers the freezing point. With
this known cushion, the production of cold does not result
from the latent heat of fusion but from the gradual reheating
of the gel. This known cushion has the property that it is of
simple construction and retains good flexibility and
suitability to flexible deformation due to the fact that the
gel does not go through a solid phase. On the other hand, it
has the drawback of a short working life since the production
of cold does not result from the latent heat of fusion but
from the gradual reheating of the gel. Moreover, the
productivity of the cushion (the production of cold or the
extraction of calories per unit of time) is not constant but
decreases as the gel is reheated, which represents a further
drawback for this known cushion.
Document WO 97/11657 describes alveolar panels that
are formed of a grid of cells filled with a thermal agent.
Between the cells, the panel has rectilinear zones with a low
breakpoint that allow to divide it at will (by shearing or
tension) into thermal cushions of predetermined sizes
depending on the applications for which these cushions are
intended. In these alveolar panels, the interstices are the
cause of several drawbacks. For one thing, they reduce the
thermal capacity of the panel and for another they present an
obstacle to homogeneous action of the panel when the latter is
applied onto a patient's skin.
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Document FR 1 018 835 A describes thermal cushions
that comprise a network of compartments with a thermal
substance and which are connected to each other by flexible
membranes. The network of compartments is enclosed in a
flexible envelope forming, together with the compartment
walls, a chamber that is filled with a thermal fluid. These
known thermal cushions have poor flexibility and are difficult
to deform, mainly when the thermal fluid of the envelope is a
liquid or a solid substance in the state of particles. They
are therefore ill-suited to uniform application on a human or
animal limb.
Summary of the invention
The invention aims to overcome the above-mentioned
drawbacks of known thermal cushions and to meet the needs of
potential users (in particular in a hospital environment) by
providing a thermal cushion of a new design that combines
excellent flexibility/elasticity with being able to adapt
perfectly, even to forms in motion and with a high and lasting
calorific value at a more or less constant temperature, whose
action is homogeneous (especially when it is used on a part of
the human body), whose thickness can be maintained more of
less constant during use, whose size and shape are more or
less unlimited, that can undergo major variations in pressure
without deforming and that, thanks to its above-mentioned
properties, can adapt to many different uses, in particular in
a hospital environment, without requiring major handling.
As a result, the invention relates to a thermal
cushion comprising a network of blocks connected by
articulations and separated by interstices, said blocks
comprising a thermal substance and said interstices being
filled, at least partially, with a deformable thermal
substance, said thermal cushion being characterised in that
the articulations are selected from
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- the elastic solid bodies that are attached to the blocks and
thus form at least part of the above-mentioned deformable
thermal substance;
- the elastic membranes that are attached to the blocks and
put under pressure so that they compress a deformable body
present in the interstices, said deformable body thus
forming at least part of the deformable thermal substance;
and
- the articulations, which are permeable to a fluid present in
the interstices, said fluid thus forming at least part of
the deformable thermal substance.
The thermal cushion according to the invention is
intended to be brought into contact with a physical body with
the aim of affecting the heat exchanges of this body with the
surrounding environment.
The expression "body" is to be understood in a
general sense as referring to a material object. It refers
without distinction to a solid, liquid or gaseous body. In the
case of a solid body, it may for example be the surface of a
solid object or a part of the anatomy of an animal or of a
human being. In the case of a liquid body, it may be the
surface of a table of a liquid bath. In this application of
the invention, the cushion may for instance act as a sealed
partition between two different liquids or between a liquid
and a surrounding atmosphere, for example the environment. In
the case of a gaseous body, it comprises an atmosphere. In
this application of the invention, the cushion according to
the invention may for instance form a screen between two
different atmospheres, for example a hot atmosphere (the
atmosphere of an industrial furnace) and an atmosphere at
moderate temperature. As a variant, in the case of a liquid or
gaseous body, it may possibly be enclosed in a sealed
envelope, for example a flexible membrane.
CA 02543778 2006-04-26
The ambient environment may be a gaseous or liquid
environment. In the case of a gaseous environment, it may for
instance be atmospheric air, the atmosphere of a heated room,
the atmosphere of a refrigerated room (for example a cool
5 store) or the atmosphere of an industrial furnace (non-
exhaustive list). In the case where the surrom~3ina
environment is a liquid environment, it may for instance be
water or an industrial chemical bath.
In the present document, the expression "normal
temperature of use" refers to the temperature of the thermal
substance of the blocks and/or the interstices when the
cushion is used.
In the present document, the term "cushion" refers in
a very general sense to any solid and flexible element
intended to be brought into contact with the body (as defined
above) so as to cover it at least partially or to wrap it
entirely or partially. The thermal cushion according to the
invention can therefore be adapted in very varied ways
depending on the use it is intended for. It may for example
take the form of an article of bedding (pillow, cover,
mattress), a pocket, a sleeve, an article of clothing or part
of an article of clothing, a packaging, a screen or curtain, a
covering (non-exhaustive list). It may be made in various
modules that can be assembled.
The thermal cushion according to the invention is a
cushion which, when it is brought into contact with a body (as
in the above definition), at normal temperature of use, causes
a transfer of heat between said cushion and said body or
contributes to maintaining the temperature of said body more
or less constant.
The thermal cushion according to the invention is
termed "calorific cushion" or "cryogenic cushion" when its
normal temperature of use is different from that of the body
with which it is brought into contact, so that a heat transfer
CA 02543778 2006-04-26
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occurs between said cushion and said body. When the heat
transfer is occurring naturally in the direction from the body
towards the thermal cushion, it is a cryogenic cushion. In the
case when the heat transfer occurs in the direction from the
thermal cushion to the body, the thermal cushion according to
the invention is a calorific cushion.
The thermal cushion according to the invention is
termed "isothermic cushion" when its normal temperature of use
is more or less equal to that of the body with which it is
brought into contact so that there is no heat transfer between
said body and the thermal cushion. An isothermic cushion
according to the invention then provides the technical
function of a calorific insulator by forming an obstacle to
the heat transfer between the body and the ambient
environment.
The thermal cushion according to the invention
comprises a network of blocks between which interstices are
provided. The interstices are generally connected to each
other.
By definition, each block of the cushion is a solid
element. The shape of the blocks of the cushion according to
the invention will be detailed later on.
The blocks are assembled in a network. They are
moreover spaced so as to form a network of interstices between
them. The cushion according to the invention thus comprises an
interwoven structure of interstices in an interwoven structure
of blocks. The network of blocks generally comprises a single
layer or stratum of blocks although a network formed by
several layers of superposed blocks is not excluded from the
invention.
The blocks of the network are articulated with each
other. In other words, the blocks of the network are connected
to each other by articulations. Details concerning the
articulations will be provided later on.
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In the cushion according to the invention, the shapes
and sizes of the blocks, the shapes and sizes of the
interstices and the choice of the articulations are adapted so
that the network of blocks forms a solid structure that is
deformable by bending and/or twisting and/or rotation around
multiple axes distributed in a three-dimensional space. This
particular feature of the cushion according to the invention
allows it to easily adapt to virtually any shape of body to
which it is applied (for example part of the human or animal
anatomy) and to follow its movement.
In the cushion according to the invention, the blocks
and the interstices comprise a thermal substance. The thermal
substance will be explained later on.
The shapes of the blocks depend on the use of the
cushion and are not critical to the definition of the
invention. The blocks may for example have a spherical,
hemispherical, ovoid, annular, lenticular, conical, truncated
conical or polyhedral shape. The blocks may have flat, curved
or skewed faces, for example helicoidal, or may comprise an
assembly of flat faces and of curved or skewed faces. They may
for instance have the shape of little barrels that combine a
curved annular face and flat faces at the ends. In general,
any shape is acceptable which, associated with the interstices
and articulations connecting the blocks, allows the
deformation of the cushion as explained above. Polyhedral
shapes are generally preferred.
Among the polyhedral shapes, right-angled or
pyramidal polyhedrons are preferred. Truncated pyramids are
especially recommended. Among right-angled or pyramidal
~0 polyhedrons, polyhedrons with triangular, trapezoidal, square,
rectangular or octagonal bases are preferred.
In a preferred embodiment of the invention, each
block is formed by two truncated pyramids joined along their
long bases, for example two triangular, trapezoidal, square or
CA 02543778 2006-04-26
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octagonal truncated pyramids. In this preferred embodiment of
the invention, the blocks are advantageously articulated in
the geometrical plane of the above-mentioned long bases of the
two truncated pyramids.
As explained above, the interstices arranged between
the blocks have the function of allowing the motion of these
blocks around the articulations that connect them. The shapes
of the interstices will depend on various parameters such as
the type of deformation desired for the network of blocks
(single-axis, double-axis or triple-axis bending, twisting,
stretching or combination of two or several of these
deformation types), the degree of deformation, the shapes and
sizes of the blocks, the articulations used and the
arrangement of the articulations between the blocks.
In the thermal cushion according to the invention,
the blocks are made of a thermal substance. The thermal
substance of the blocks gives its thermal properties to the
thermal cushion according to the invention. In the case of a
cryogenic cushion, the thermal substance of the blocks is
selected from those which, once brought to normal temperature
of use and then subjected to cooling, release a large quantity
of heat. In the case of a calorific cushion, the thermal
substance of the blocks is selected from those which, once
brought to normal temperature of use and then heated, pick up
a large quantity of heat. In the case of an isothermic
cushion, the thermal substance of the blocks is selected from
those which block the heat transfer or which, once brought to
normal temperature of use, then require a large input of heat
in order to change their temperatures. Thermal substances
3C9 which, at normal temperature of use, have a high specific heat
are generally suitable for the three types of cushion
according to the invention. These thermal substances are those
known and used in technology for their property of
CA 02543778 2006-04-26
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accumulating large quantities of heat and which are found in
particular in applications as thermal accumulators.
In the thermal cushion according to the invention,
blocks may be entirely made of the thermal substance which is
then necessarily solid at normal temperature of use as well as
in normal conditions of handling for the thermal cushion. As a
variant, blocks may, in addition to the thermal substance,
comprise another substance which does not on its own perform
the function of the thermal substance as defined above. The
thermal substance may be identical in all the blocks or may
differ depending from the block. Moreover, each block may
comprise a single thermal substance or a mixture of two or
several thermal substances. In the present document, the
expression "thermal substance" refers without distinction to a
single thermal substance or to a mixture of different thermal
substances.
In one particular embodiment of the thermal cushion
according to the invention, the blocks comprise cells inside
which the thermal substance is held. This embodiment of the
thermal cushion according to the invention is especially well
suited to the case where the thermal substance of the blocks
is not solid at normal temperature of use or in normal
conditions of handling for the thermal cushion. In this
embodiment of the cushion according to the invention, the
outer shape of the cells must meet the above-mentioned shape
requirements with regard to the blocks. The choice of the
substance for the cells is determined by the need for said
cells to be chemically inert relative to the thermal substance
that they comprise and relative to the chemical and thermal
environment during their normal use. The cells must also have
mechanical properties that are compatible with the mechanical
stresses to which the cushion is normally subjected at normal
temperature of use or in the course of handling and they must
be more or less incapable of deformation (they must be made of
CA 02543778 2006-04-26
a rigid or semi-rigid material and of a suitable shape). In
this particular case, each cell may be entirely isolated from
the neighbouring cells or, as a variant, the cells may be in
contact with each other so as to allow the fluid content of
5 said cells to circulate between them. In the case where the
thermal substance of the cushion is liquid or gaseous, the
walls of the cells are usually impermeable to liquids or
gases. Plastic materials are generally suitable for making up
the cells. Useful plastic materials include polyolefins, in
10 particular polymers and copolymers of ethylene and propylene,
chlorinated polymers, especially vinyl chloride and vinylidene
chloride polymers and copolymers, styrene-ethylene-butyl-
styrene copolymers and polyurethane. Polyethylene,
polypropylene, vinyl polychloride and styrene-ethylene-butyl-
styrene copolymers are suitable in most applications. As a
variant, the cells may also be made of metal, for example by
drawing sheets of malleable metal or alloy such as aluminium
and aluminium alloys. According to another variant, the cells
or some of them are formed from composite materials: one part
of the cell is made of one material and another part of the
cell is made of another material. According to an additional
variant, one part of the network of cells is made of one
material and another part of the network of cells is made of
another material.
Any known forming method may be used to produce the
network of cells. The methods of casting, pressing, drawing
and injection are suitable.
According to a suitable method, a corrugated sheet of
a plastic or metal material is formedo which thus has a
network of holes or half-cells. Another sheet is then glued or
welded onto the corrugated sheet so as to block the holes of
the corrugated sheet and to form the cells. This other sheet
may be a corrugated or a flat sheet.
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In one preferred embodiment of the invention, the
thermal substance of the blocks comprises a substance that
undergoes a change of state at normal temperature of use. In
this embodiment of the invention, the expression "change of
state" is considered in its general sense and covers any
physical and/or chemical change of the substance, occurring at
a more or less constant temperature and characterised in the
latent heat of the change of state. Depending on the substance
used, the change of state may in particular comprise the
fusion of a solid, solidification of a liquid, vaporisation of
a liquid, condensation of a gas, total or partial hydration of
a salt, total or partial dehydration of a salt,
crystallisation of an amorphous solid or recrystallisation of
an allotropic form of a crystal into another allotropic form.
In this embodiment of the invention, the thermal substance of
the blocks may be entirely made of said substance that
undergoes a change of state at normal temperature of use. As a
variant, the thermal substance of the blocks may also comprise
other substances or materials that do not undergo a change of
state at normal temperature of use. Then, in order to avoid
overburdening the text to no purpose, it will be assumed that
it is the entire thermal substance that undergoes a change of
state at normal temperature of use. It is in any event clearly
understood that, as explained above, the invention does not
exclude the case in which only a part of the thermal substance
of the blocks undergoes a change of state (in the event, when
it is made of a mixture of several chemical compounds of which
only one undergoes a change of state at normal temperature of
use or when an additional material is incorporated which is
not involved in the thermal function of the thermal cushion,
for example a magnet).
In the above-defined preferred embodiment, the change
of state undergone by the thermal substance of the blocks at
normal temperature of use corresponds to a heat absorption by
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said material in the case of a cryogenic cushion and to the
emission of heat in the case of a calorific cushion. In the
case of an isothermic cushion, the change of state undergone
by the thermal substance of the blocks at normal temperature
of use corresponds to a heat absorption by said thermal
substance when said normal temperature of use (which is also
that of the body for which the cushion is intended) is lower
than that of the surrounding environment. The change of state
corresponds to an emission of heat by the thermal substance
when the normal temperature of use is higher than that of the
surrounding environment.
In order to use a thermal cushion true to the
preferred embodiment that has just been described, the state
of the thermal substance of the blocks should be suitably
selected. In the case where the cushion is used as a cryogenic
cushion, it is necessary first of all to bring the thermal
substance of the blocks to a state which, at normal
temperature of use, will undergo a change of state
corresponding to a heat absorption (for example the fusion of
a solid or the vaporisation of a liquid). In the case where
the cushion is used as a calorific cushion, it is first
necessary to bring the thermal substance of the blocks to a
state which, at normal temperature of use, will undergo a
change of state corresponding to a heat production (for
example the solidification or crystallisation of a liquid or
the condensation of a gas). In the case where the cushion is
used as an isothermic cushion, in a surrounding environment at
a temperature that is higher than the normal temperature of
use, it is first necessary to bring the thermal substance of
the blocks to a state which, at normal temperature of use,
will undergo a change of state corresponding to a heat
absorption (for example the fusion of a solid or the
vaporisation of a liquid). In the case where the cushion is
used as an isothermic cushion, in a surrounding environment at
CA 02543778 2006-04-26
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a temperature that is lower than the normal temperature of
use, it is first necessary to bring the thermal substance of
the cells to a state which, at normal temperature of use, will
undergo a change of state corresponding to a heat production
(for example the solidification or crystallisation of a liquid
or the condensation of a gas). Moreover, all other things
being equal in the preferred embodiment that has just been
described, the best results are obtained with thermal
substances which, at normal temperature of use, have a high
latent heat of change of state.
In the preferred embodiment that has just been
described, the thermal substance of the blocks undergoing a
change of state at normal temperature of use may be a pure
body. As a variant, it may be a chemical composition that is
congruent to said normal temperature of use so that the change
of state occurs at a more or less constant temperature.
In the preferred above-described embodiment and its
implementation variants, the choice of thermal substance for
the blocks depends on the normal temperature of use of the
cushion. This is itself dependent on the application for which
the thermal cushion is intended. Water and aqueous solutions
are normally suitable in the particular case of a cryogenic
cushion intended for therapeutic applications. Pure water is
suitable in the case of applications where the normal
temperature of use of the cushion is close to 273K (0°C) . For
applications where the normal temperature of use is lower than
273K, aqueous solutions are recommended in which the dissolved
body and its concentration are selected depending on the
normal temperature of use of the cryogenic cushion. It is
recommended that the dissolved body and its concentration are
selected in such a way that partial or total precipitation of
said dissolved body is avoided at the normal temperature of
use of the cushion. Examples of dissolved bodies include
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sodium chloride, calcium chloride, sodium carbonate, propylene
glycol, glycerine, ethyl alcohol and propyl alcohol.
As explained above, when the thermal substance of the
blocks is liquid, it is enclosed in cells whose walls are
generally impermeable to liquids. When a liquid thermal
substance that undergoes vaporisation at normal temperature of
use is used, it may turn out advantageous to use, for the
cells, walls with oriented permeability or walls that are
impermeable to the liquid phase of the thermal substance but
permeable to its gaseous phase (for example impermeable/
breathable PU). However, the invention is not limited to this
embodiment and it also covers the case where the walls of the
cells are impermeable to the liquid phase and to the gaseous
phase of the thermal substance of the cells.
In the thermal cushion according to the invention,
the thermal substance of the blocks forms the main active
element of the cushion and gives it its thermal properties
(cryogenic, calorific or isothermic properties, depending on
the intended use).
The thermal substance of the interstices has the
function of increasing the effectiveness of the cushion by
increasing its active surface and its active volume. The
thermal substance of the interstices must have thermal
properties that are analogous to those mentioned above for the
thermal substance of the blocks. Its thermal properties must
therefore be adapted to the intended purpose of the cushion,
to its normal temperature of use, to the temperature of the
body for which the cushion is intended and to the ambient
temperature. As regards the thermal properties of the thermal
substance of the interstices, what was explained above for the
thermal substance of the blocks may therefore be repeated.
The thermal substance of the interstices must also be
deformable. This additional property of the thermal substance
of the interstices is necessary to allow the movement of the
CA 02543778 2006-04-26
articulated blocks and the deformation of the cushion. The
choice of the thermal substance of the interstices and/or its
implementation are therefore dependent on the structural
parameters of the cushion such as the shape of the blocks, the
5 shape of the interstices separating the blocks, the
articulations of the blocks and the positions of these
articulations in the network of the blocks.
In a particular embodiment of the thermal cushion
according to the invention, the thermal substance of the
10 interstices comprises an elastic, solid body. This may for
example comprise foam in synthetic polymer or an elastomer,
for example a natural or synthetic rubber. In the case of
foam, it may be of a type with open pores or of a type with
closed pores. In the case of foam with closed pores, these
15 pores may be filled by a gas with a coefficient of heat
transmission that is lower than that of air, for example
nitrogen or argon.
In another embodiment of the thermal cushion
according to the invention, the thermal substance of the
interstices comprises a fluid. The fluid may comprise a
liquid, a gas, a gel (or viscous fluid) or a solid in the form
of crumbly particles (for example a powder). In this
embodiment of the invention, the interstices must be sealed so
as to retain the thermal substance. The sealing means used
should not be an obstacle to the movement of the blocks on
their articulations. Additional information concerning the
sealing means of the interstices will be provided later on.
In the thermal cushion according to the invention,
the interstices may be partially or completely filled by the
thermal substance. It is preferable for the interstices of the
network of blocks to be completely filled with the thermal
substance.
Depending on the applications for which the thermal
cushion according to the invention is intended, substances
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capable of reflecting infrared radiation or ultraviolet
radiation may possibly be incorporated into the thermal
substances of the blocks and the interstices and/or, where
relevant, to the membranes or envelopes. Examples of such
reflective substances include in particular aluminium powders.
Similarly, for other particular applications, substances
capable of absorbing infrared radiation such as for instance
carbon powder may be advantageously incorporated into the
thermal substances and/or, where relevant, into the membranes
or envelopes.
In the thermal cushion according to the invention,
the interstices between the blocks may be open. This
embodiment of the invention is suitable when the deformable
thermal substance of the interstices is a deformable solid
(for example foam) at normal temperature of use and in normal
handling conditions for the thermal cushion. Alternatively the
interstices between the blocks may be sealed by a sealing
means. This alternative is necessary in the case where the
thermal substance of the interstices is a fluid (as defined
above) in normal conditions of use and of handling for the
thermal cushion. It is also suitable in the case where the
thermal substance of the interstices is a deformable solid
body. As mentioned above, it is appropriate to choose a
sealing means that does not form an obstacle to the movement
of the articulated blocks.
The thermal cushion according to the invention is
characterised by the design of the articulations of the
blocks. It is characterised in particular by an original
selection of said articulations, associated to a selection of
the thermal substance of the interstices, sothat the network
of blocks may undergo deformations in the three spatial
dimensions, by stretching, twisting and rotation.
As a result, according to a first implementation of
the invention, the articulations of the blocks comprise
CA 02543778 2006-04-26
1~
elastic solid bodies that are attached to the blocks and
therefore constitute at least a part of the thermal substance
of the interstices. Information concerning the elastic solid
body was given above.
In this first implementation of the invention, the
attachment of the elastic solid body to the blocks may be
achieved by any appropriate means, for example gluing, welding
or by means of screws or pegs (non-exhaustive list).
In a second implementation of the invention, the
articulations of the blocks comprise elastic membranes that
are attached to the blocks and put under tension in such a way
as to compress a deformable body, present in the interstices,
said deformable body thus forming at least a part of the
deformable thermal substance. The deformable body may be an
elastic solid body or a fluid. In the case of a fluid, it may
be an incompressible fluid or a compressible fluid.
Information concerning the elastic solid bodies and the fluids
was given above.
In this implementation of the invention, each
interstice may be covered by an individual membrane. The
membranes are therefore appropriately attached to the blocks
so as to allow them to be put under tension. Any appropriate
means may be used, for example gluing or welding. The
attachment of the membranes to the blocks must be sealed when
the thermal substance of the interstices is fluid (gas or
liquid). In a particular variant of the above-mentioned second
implementation of the invention, an impermeable and elastic
sheet covers at least a part of or the entire network of
blocks and it therefore substitutes for the individual
membranes sealing the interstices. In another particular
variant of the above-mentioned second implementation of the
invention, the network of blocks is enclosed in a sealed and
elastic envelope. In this other variant, the envelope may be
appropriately attached to the blocks in order to block the
CA 02543778 2006-04-26
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interstices so that they are sealed when the thermal substance
of the interstices is fluid (gas or liquid). In the case where
the thermal substance of the interstices is a deformable solid
(for example foam or elastomer), the envelope may equally be
attached to all the blocks in the network of blocks, to some
of them (and not to others) or not be attached to any block.
The attachment of the envelope to the blocks may be achieved
by any appropriate means. Appropriate means include gluing and
welding. The envelope may be simple or it may comprise a
complex film or it may comprise several layers linked to each
other or not. It may be of different composition depending on
each face. It may have treatments and additives that give it
specific active properties depending on the use. It may
comprise intake/outlet tubes for the introduction or the
circulation of the thermal substance of the interstices when
it is a fluid.
In a third implementation .of the invention, the
interstices between the blocks comprise a fluid and the
articulations are permeable to said fluid. In this
implementation of the invention, the fluid may comprise a
liquid, a gas, a gel or a solid in the form of crumbly
particles (for example a powder) and it forms at least a part
of the deformable thermal substance of the interstices.
Information concerning the fluid of the interstices was given
above. In this third implementation of the invention, the
selection of the articulations will depend on the state of the
fluid present in the interstices. Said articulations may for
example comprise flexible membranes (possibly elastic) that
are porous to gases or liquids, flexible and perforated
partitions, lattices, hinges with perforations or any other
articulation not likely to hinder the free circulation of the
fluid present in the interstices.
Depending on the type of deformable thermal substance
present in the interstices, the cushion according to the
CA 02543778 2006-04-26
19
invention may associate several types of articulation, for
example elastic solid bodies attached to the blocks, pivots
and membranes. As a variant, in additional to the
articulations, the blocks of the network may be linked to each
other by rigid lugs whose mechanical resistance to bending is
low and controlled. In this variant of the invention, the
rigid lugs serve to give rigidity to the cushion and to make
it easier to handle and they break when the cushion is applied
to the body and deformed.
The thermal cushion according to the invention has
the advantageous property of combining excellent heat storage
and thermal exchange properties with excellent
flexibility/elasticity that allows it to immediately adapt to
the form of a physical body to which it is being applied in
such a way that it perfectly fits the form of this body and
therefore ensures homogeneous regulation of the temperature or
of the heat exchanges over the whole covered surface of said
body. Due to the design and structure of the thermal cushion
according to the invention, its thickness has no effect on its
flexibility and its ability to be deformed. In other words,
the invention allows to adapt the thickness of the cushion to
the desired thermal properties (to its thermal capacity)
without adversely affecting its flexibility or its ability to
easily adapt to various body shapes.
In another particular embodiment of the thermal
cushion according to the invention, the network of blocks
bears, on at least a part of its surface, a sealed and elastic
envelope, generally provided with a device for the intake and
outlet of a fluid (for example a gas). In this embodiment of
~Q the invention, the envelope is intended to be brought into
contact with the above-mentioned physical body, with which a
heat exchange must occur. By introducing a defined volume of a
suitable fluid (normally air) into the envelope, it is
CA 02543778 2006-04-26
possible to control the heat transfer between the thermal
cushion and the physical body.
In the thermal cushion according to the invention,
the network of blocks may be arranged in a single layer. As a
5 variant, the network of blocks may be formed by the
superposition of several layers. The layer or the assembly of
layers may advantageously be held as a sandwich between two
sealed and elastic envelopes, usually being each provided with
an intake and outlet device for a fluid (for example a gas).
10 In this embodiment of the invention, one of the envelopes
therefore serves, by resting on an appropriate support (for
example a bandage or a shell), to apply the thermal cushion
onto the body with a defined pressure. The other envelope
serves to control the heat transfer between the thermal
15 substances and the body, as explained above.
The thermal cushion according to the invention has
numerous applications. It can be used in particular as an
isothermic cushion (or thermostat) to maintain the temperature
of containers such as bottles or thermostatic flasks. Such use
20 of the thermal cushion according to the invention has
applications in the industry for maintaining chemical products
at predefined temperatures as well as in the food sector for
heating, cooling and maintaining the temperature of chambers
for food products.
The thermal cushion according to the invention also
has applications as a cryogenic cushion, in particular in the
chemical or pharmaceutical industry for keeping chemical
products at low temperatures as well as in the food industry
for preserving food products.
Because of its form-fitting and deformable nature,
the thermal cushion is particularly suitable for applications
associated with wellbeing both in the form of articles of
clothing and various healthcare articles (for example
compresses, masks, massage tools).
CA 02543778 2006-04-26
21
Because of its excellent ability to deformation, the
thermal cushion according to the invention is especially
adapted to medical, paramedical and sports applications, in
particular for thermal regulation and cryotherapy. Cryotherapy
is a medical technique that is widely used, especially for
relieving pain (for example headaches, migraines, toothaches,
muscular or inflammatory pains) so as to aid the resorption of
hematomas or edemas and the healing of accidental or surgical
wounds.
The invention therefore also relates to a device
comprising a thermal cushion according to the invention for
the therapeutic treatment of human or animal bodies.
In the device according to the invention, the cushion
and its network of blocks are adapted to the method of
treatment or depending on the part of the human or animal body
for which said device is intended.
In a particular embodiment of the device according to
the invention, the cushion is placed inside a rigid shell. In
this embodiment of the device according to the invention, the
shell is normally adapted to the part of the human or animal
body to which the thermal cushion must be applied. It has, for
example, the form of an elbow, a knee, a finger, a foot or a
skull.
In this embodiment of the device according to the
invention, the shell may be formed of two or several
articulated elements to make it easier to put it on the human
or animal body. This embodiment of the device according to the
invention is especially recommended if the device is intended
to be applied to the head of a person or of an animal.
In an advantageous variant of the embodiment that has
just been described, a sealed and elastic envelope is inserted
between the shell and the network of blocks of the cushion and
this envelope is usually provided with an intake and outlet
device for a fluid. This variant of the invention achieves
CA 02543778 2006-04-26
22
homogeneous application of the thermal cushion over the human
and animal body. It also allows the application of the thermal
cushion to the human or animal body with a defined pressure,
regulated by the pressure of the fluid allowed into the
envelope.
In another variant of the embodiment described above,
a panel is articulated to the shell and sized in such a way
that it can form, together with the shell, a hermetic chamber
comprising the thermal cushion. In this variant of the device
according to the invention, the thermal cushion and the shell
form an integral part of a hermetic case used for handling the
device. By using a panel that is suitably insulated, the
device thus designed allows to maintain predetermined thermal
properties. In this way, the device is especially well suited
for use in the case of an emergency outside of a hospital, for
example on the public highway. In the above-mentioned variant
of the device according to the invention, the shell and the
articulated panel may be provided with medical instrumentation
with for example thermometers or tensiometers. It may also be
provided with an independent device for generating heat or
cold during the handling of the device, in particular during
its transportation or storage.
The invention also relates to a thermal wall
comprising an assembly of thermal cushions according to the
invention, between two partitions or between a partition and a
body. The thermal wall may be a calorific wall, a cryogenic
wall or an isostatic wall, depending on whether the thermal
cushions collected between its two partitions are calorific
cushions, cryogenic cushions or isostatic cushions.
The thermal wall according to the invention may for
example form the wall of a thermos.
In the thermal wall according to the invention,
thermal cushions are preferably used in which the network of
blocks is arranged in an envelope filled with a deformable
CA 02543778 2006-04-26
23
thermal substance. At least a part of the thermal substance of
the envelope may comprise the thermal substance of the
interstices.
Short description of the figures
Special features and details of the invention will be
made clearer in the following description of the attached
figures which show some particular embodiments of the
invention.
Figure 1 is a schematic view in cross-section of a
particular embodiment of the thermal cushion according to the
invention;
Figure 2 shows a perspective view, with partial
cutaway, of a detail of the thermal cushion of Fig. 1;
Figure 3 shows a detailed perspective view of Fig. 2;
Figure 4 shows, in horizontal section, another
embodiment of the thermal cushion according to the invention;
Figure 5 shows the thermal cushion of Fig. 4 in
vertical section;
Figure 6 shows a perspective view of a particular
embodiment of the device according to the invention;
Figure 7 is a side view, with partial cutaway, of
another embodiment of the device according to the invention;
Figure 8 is a back view of the device of Fig. 7;
Figure 9 is a sketch, in cross-section, of a third
embodiment of the device according to the invention;
Figure 10 shows in vertical cross-section a thermal
wall according to the invention;
Figure 11 shows a thermal cushion according to the
invention that can be used in the thermal wall of Fig. 10; and
Figure 12 shows another thermal cushion according to
the invention that can be used in the thermal wall of Fig. 10.
The figures are not drawn to scale.
CA 02543778 2006-04-26
24
The same reference numbers generally refer to the
same elements.
Detailed description of particular embodiments
The thermal cushion shown in Fig. 1 and 2 comprises a
network of blocks l, formed by hollow cells. The blocks or
cells 1 have the shape of prisms with square bases . Each cell
1 is formed by two truncated pyramids 3 and 4, attached along
their long square bases. The side ridges of the two truncated
pyramids have bevelled edges (2). The network of cells 1 is
formed by the assembly of two corrugated sheets 5 in a
flexible polymer material (for example in plastified polyvinyl
chloride or in styrene-ethylene-butyl-styrene copolymer) pre-
drawn and welded to each other along tongues 6 between the
cells (a corrugated sheet 5 is shown in Fig. 3). The tongues 6
are flexible and elastic and they act as articulations between
the cells 1. They are pierced by apertures 9 whose function
will be explained later on. By bending or twisting the
assembly of sheets 5, the cushion of cells may thus adopt
complex profiles to fit an appropriate body, for example part
of the anatomy of a human being or of an animal.
The thermal cushion of Fig. 1 to 3 is a cryogenic
cushion intended for use in cryotherapy. To this end, the
cells 1 are filled with a suitable thermal substance whose
definition was given above. The thermal substance is
advantageously an aqueous solution with a freezing point that
is congruent and occurs at a temperature corresponding to the
temperature at which the cushion is intended (normal
temperature of use). When the normal temperature of use is
close to 273K (or 0°C), the aqueous solution may be replaced
by distilled or mineral water.
The interstices 8 defined between the cells 1 and the
tongues 6 are filled with a deformable thermal substance 10
(shown in Fig. 1 only). The thermal substance 10 shown in Fig.
CA 02543778 2006-04-26
1 is an elastic solid body, for example a solid mass made of
elastomer or polymer foam. It is preferably selected so as to
have a high specific heat at normal temperature of use.
A flexible and elastic envelope 7 surrounds the
5 network of cells 1 and interstices 8. The elastic envelope 7
is for instance a film of styrene-ethylene-butyl-styrene
copolymer.
Before using the thermal cushion of Fig. 1 to 3 in a
therapeutic application, it is maintained, for instance i n
a
10 cool store, at a temperature low enough to freeze the aqueous
solution of the cells 1. The thermal cushion is taken out of
the cool store when it is about to be used and it can be
immediately applied to a part of the human body that is to be
subjected to cryogenic therapy, for example a hand, the head
15 or an arm. Due to the flexibility of the envelope 7 and
tongues 6 and to the elasticity of the thermal substance 10
contained in the interstices 8, the cushion deforms and
perfectly adapts to the morphology of the human body.
In a modified embodiment of the thermal cushion of
20 Fig. 1 to 3, the elastic envelope 7 is welded to the cell s
1
and put under tension so that the elastic solid body 10 of the
interstices 8 is maintained in a state of elastic compression
in these interstices 8.
When the thermal cushion shown in Fig. 1 to 3 is used
25 for a medical therapy, a compress can be inserted between the
thermal cushion and the anatomical part of the human body. Any
compress usually used in medical therapy is suitable. It may
for example comprise a gauze. After the thermal cushion is
placed on the compress, it is firmly attached to the part of
the body to be treated by means of a bandage (adhesive or
otherwise) so that when it deforms, it perfectly fits the
entire part of the body to be treated. As a variant, the
cushion may itself be provided with medical adhesive parts of
CA 02543778 2006-04-26
26
a repositionable type. In this particular case, the bandage is
not required.
In order to improve the thermal action of the cushion
on the anatomical part treated, a second thermal cushion may
be advantageously placed on the first thermal cushion. In this
case, only the first thermal cushion [the one directly applied
to the human body (or to the compress)] is put in the cool
store, the other thermal cushion being maintained at ambient
temperature. In this application, the second thermal cushion
may act as a thermal insulator. It may in particular act as an
insulating bandage for attachment and/or compression. It may
be provided with an inflatable pocket for optimum application
to concave body forms.
In some embodiments, the cushion may combine in a
single item the thermal function and the function of an
insulating bandage and may comprise the above-mentioned
compress that is inserted between the thermal cushion and the
anatomical part of the human body.
In a modified embodiment of the thermal cushion of
Fig. 1 to 3, the tongues 6 are pierced by apertures 9 (whose
function will be explained later) and the thermal substance 10
of the interstices 8 is in a liquid or gel state at normal
temperature of use. In this embodiment of the cushion, the
envelope 7 is attached to the cells 1 so as to hermetically
seal the interstices 8. The apertures 9 have the function of
allowing the circulation of the fluid thermal substance in the
network of interstices 8 when the cushion is subjected to
deformation.
The structure of the thermal cushion possibly allows
its use by circulation of fluid in the interstices and/or
cells (connected by filling/circulation channels).
Reactions of thermogenic/cryogenic mixtures may be
used to initiate the thermal function independently or to
CA 02543778 2006-04-26
27
extend the duration of the action without requiring the
cushion to be removed and recharged.
The cushion may comprise elements for the control and
regulation of the temperature.
In the embodiment shown in Fig. 4 and 5, the cushion
comprises a network of cells 1 between which a network of an
elastic solid mass 10 is inserted. The elastic solid mass 10
is for example a solid mass of elastomer or a foam of polymer
resin. The elastic network 10 is attached to the network of
cells 1 by gluing or welding. The elastic network 10 also acts
as an articulation between the cells 1.
Fig. 6 shows the use of the thermal cushion according
to the invention in a device for the therapeutic treatment of
an element of the human body. The therapeutic treatment may
for example be the cryogenic treatment of an arm or a thigh.
To this end, the device comprises a thermal cushion referred
to in its entirety by the reference number 11. The thermal
cushion comprises, as explained above, a network of blocks 1
and interstices 8, comprising suitable thermal substances. The
thermal cushion 11 is attached to a bandage 12 intended to
attach it to a person's arm. A rectangular aperture 13 is made
in the network of blocks 8. The aperture 13 serves to give
access to a defined area of the arm in order to subject it to
a suitable therapeutic treatment (for example to treat a
wound, a contusion or another local condition there). The
aperture 13 may be used to apply a dressing to the arm. As a
variant, it may be filled by a small removable thermal cushion
according to the invention. The thermal cushion 11 of the
device of Fig. 6 may for example be a cryogenic cushion,
designed to put an arm into hypothermia while the zone
accessible through the aperture is subjected to a suitable
therapeutic treatment.
The device of Fig. 6 may obviously be adapted to the
treatment of the limb of an animal, for example a horse's leg.
CA 02543778 2006-04-26
28
Fig. 7 and 8 show a device according to the invention
for the therapeutic treatment of a person's skull. The device
comprises a rigid shell 14 that takes the form of a helmet
closely fitting the person's head 15 and neck. The helmet 14
is made up of three articulated elements 16, 17 and 18 (Fig.
8). Element 16 serves to cover the top of the skull and
elements 17 and 18 are intended to surround the neck. The
inner part of the helmet 14 is shown at a larger scale in a
zone marked by the reference X in Fig. 7. It comprises a
thermal cushion under the shell 14. The thermal cushion is
true to the invention and successively comprises an insulating
layer 19, a sealed envelope 20 (whose function will be
explained later on), a network 11 of articulated blocks
comprising a thermal substance and a second sealed envelope
22. The sealed envelope 20 comprises a device (not shown) for
injecting a fluid under pressure into it. This is usually air
that is injected into the pocket by means of an electric or
manual pump (of the type used for bicycles or used on medical
or paramedical tensiometers). The pocket 22 is similar to the
pocket 20 and is also designed for injecting a defined volume
of air under pressure. When it is necessary to subject a
patient's head to cryogenic treatment, for example to put it
into hypothermia, the helmet 14 and its thermal cushion are
maintained in a cool store for an appropriate period so that
they reach a predetermined temperature. Element 16 of the
helmet 14 is then applied to the top cf the skull on the
patient's head 15 and elements 17 and 18 are folded around the
patient's neck. A defined volume of air is then injected into
the pocket 20 so as to apply the network of articulated blocks
11 with a predetermined pressure onto the patient's head 15.
Then, a defined volume of air is possibly injected into the
pocket 22. The air pocket 22 acts to form an insulating film
between the network of blocks 11 and the head 15 so as to
regulate the heat flux between the head 15 and the thermal
CA 02543778 2006-04-26
29
substance of the blocks 11 of the thermal cushion. The heat
flux is controlled at will by choosing an appropriate volume
of air to be inj ected into the pocket 22 . The shell 14 of the
device of Fig. 7 and 8 may advantageously be provided with
medical tools with for example thermometers or tensiometers.
Fig. 9 shows a variant of the embodiment of the
device of Fig . 7 and 8 . In the device of Fig . 9 , the shel l 14
has the shape of a hemisphere adapted to cover the top of a
person's skull. It is made up of two elements 23 and 24
articulated on a ring 25 intended to surround the cranium at
the level of the forehead. The elements 23 and 24 each have a
thermal cushion according to the invention (not shown) on
their inner faces. Two panels 26 and 27 are moreover
articulated to the ring 25. The two panels 26 and 27 form,
together with the elements 23 and 24, a chamber in which the
thermal cushions of elements 23 and 24 are enclosed. The shell
14 and its thermal cushions thus form an integral part of a
case (which may be hermetic and insulating) for the
transportation and handling of the device. The device shown in
Fig. 9 is especially well suited for emergency use outside of
a hospital, for example to attend an emergency on the public
highway. The shell 14 may also be provided with an independent
device for generating heat or cold during the transportation
of the device or its handling.
Fig. 10 shows another application of the thermal
cushion according to the invention. It shows part of a
cryogenic wall 28 of a thermos intended to preserve organs or
cold foodstuffs. The cryogenic wall 28 comprises a pair of
partitions 29 and 30 that define between them a chamber filled
with small cryogenic cushions 31 according to the invention.
In accordance with the invention, each cryogenic cushion 31
comprises blocks 32 (Fig. 11) connected by a flexible membrane
33 and filled with a rigid cryogenic substance, for example
ice. The network of blocks 32 is enclosed in a flexible and
CA 02543778 2006-04-26
hermetic envelope 34 filled with a fluid cryogenic substance
35. The fluid cryogenic substance 35 may for example be a gel.
The deformable nature of the cryogenic substance 35 optimises
the refrigerant properties of the wall 28.
5 Fig. 12 shows another embodiment of the cryogenic
cushions 3i that can be used in the cryogenic wall 28 of Fig.
10. In this embodiment, the cryogenic cushion comprises a
chain of blocks 32 connected by pivots 33 and comprising a
rigid cryogenic substance (for example ice). The chain of
10 blocks 32 is enclosed in a tubular envelope 34 filled with a
cryogenic gel 35.
By extension, the invention also relates to thermal
walls in which the thermal cushions comprise a single block 32
(comprising a rigid thermal substance) in a flexible envelope
15 comprising a fluid thermal substance [liquid, gas, gel or in
the state of crumbly particles (powder)].
