Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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CAPSULE FOR FOOD OR BEVERAGE PREPARATION COMPRISING AN OVERSIZED
MEMBRANE
15
Field of the invention
The present invention concerns the field of food or beverage
capsules comprising a hollow body which contains an ingredient for food or
beverage preparation. In the field of food or beverage preparation, it is
known to
use single- serve capsules for mixing an ingredient contained in said capsule,
with a
fluid fed from a pressurized source contained in a food or beverage
preparation
machine. More particularly, such capsules are adapted for preparation of a
food or
beverage preparation by dissolution into the fluid or extraction by the fluid
under a
preparation pressure. This includes preparation of coffee (in such case, the
ingredient is ground roasted coffee to be extracted into water vapour and/or
hot
liquid water), and soluble ingredients or a mix of soluble ingredients for
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preparation of a beverage such as instant coffee, hot chocolate, or a soup or
other
dehydrated edible product to be dissolved into hot or cold water or milk.
Background of the invention
The principle of extracting and/or dissolving the contents (i.e.
ingredients) of a closed capsule under pressure is known, and consists
typically of
inserting the capsule into a receptacle or cavity of a machine, injecting a
quantity
of pressurized water or other adapted fluid into the capsule, generally after
piercing a face of the capsule with a piercing injection element such as a
fluid
injection needle mounted on the machine, so as to create a pressurized
environment inside the capsule either to extract the substance or dissolve it,
and
then release the extracted substance or the dissolved substance through the
capsule.
Capsules have been developed for such an application of food
preparation, and in particular for beverage preparation, which are described
and
claimed in applicant's European patent EP 1784344 81, or in European patent
application EP 2062831.
In short, such capsules comprise typically:
- a hollow body comprising an injection wall which is
impermeable to liquids and to air and which is attached to the rest of the
body (or
made integral with the body) and adapted to be punctured by e.g. an injection
needle of the machine,
- a chamber containing a bed of ground roasted coffee to be
extracted, or a soluble ingredient or mix of soluble ingredients,
- a membrane, usually made of aluminium, disposed at the
bottom end of the capsule and fastened to the body.
The membrane closes the chamber, for retaining the internal
pressure in the chamber when pressurised fluid is introduced into the capsule.
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The opening of the chamber for beverage delivery is achieved by
increasing the pressure within the chamber. This pressure is increased by
introducing a quantity of pressurized fluid such as water into the chamber.
When
the internal pressure is sufficient, the membrane is opened upon contact with
opening means. The present invention relates to a capsule having the opening
means within the capsule, or in other words a capsule which comprises its own
opening means activated by the rise of pressure of the fluid introduced into
the
capsule at the time of beverage extraction. This type of capsule is disclosed
for
example in European patent application EP 1472156. Opening means are disposed
within the capsule, outside the chamber, in the vicinity of the membrane. When
a
sufficient pressure is established inside the chamber, the membrane tends to
be
pressed against said opening means, and is ruptured, and thus opened. The
beverage flows through the openings thus produced.
The opening means are for example formed by a so-called
"pyramid plate" comprising raised and recessed elements. The membrane engages
the raised and recessed elements of the pyramid plate under the effect of the
rise
of pressure in the chamber of the capsule until it the membrane ruptures and
opens.
Correct engagement of the membrane with the opening means
has to be obtained to provide a safely reproducible pressure inside the
capsule
when a food or beverage product is prepared, and also to provide an efficient
filter
function to the membrane in cooperation with the opening means.
Indeed, the membrane has to take the shape of the opening
means as much as possible before it opens. Correct engagement corresponds to a
state in which the membrane is deformed so as to cover a given percentage,
e.g. at
least 60%, of the overall developed surface area of the opening means (i.e. of
the
surface of the opening means in the vicinity of the membrane before a rise of
the
pressure inside the capsule).
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However, the membrane has to be made of a material that is
stiff enough to allow the pressure to rise inside the chamber up to the
desired
level. The membrane is generally made of aluminium. This material is
convenient
to form the membrane, and its implementation in a food or beverage capsule is
well known. However, the mechanical properties of the material does not allow
the membrane to be stretched to a great extent before it ruptures.
The present invention thus relates to a capsule for food or
beverage preparation configured to address the above-mentioned problem.
Summary of the invention
According to the invention, there is provided a capsule for food
or beverage preparation, the capsule comprising:
- a hollow body which is impermeable to liquids and to air and
which is adapted to be punctured for fluid injection inside the capsule,
- a chamber formed inside the body and containing an ingredient
for preparing food or beverage by dissolution into the fluid under pressure or
extraction by the fluid under pressure,
- a membrane fastened to the body to retain pressure in the
chamber, at least part of said membrane covering an opening formed in the
bottom end of the chamber, the opening being surrounded by a rim to which an
edge of the membrane is fastened by fastening means which forms a seal between
the body and the membrane, and
- opening means disposed outside the chamber in the vicinity of
the membrane, the opening means being configured to open the membrane when
said membrane is pressed against said opening means under an opening pressure.
The part of the membrane which is surrounded by the seal has a
developed surface area comprised between 110% and 140% of the surface area of
a flat surface surrounded by said seal
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The capsule according to the invention thus provides extra-
surface area (compared to the prior art) for the membrane to engage the
opening
means without being stretched, or at least without being much stretched. The
membrane is pushed in a direction outwardly of the chamber when a pressure,
more than the atmospheric pressure, is established inside the chamber by
introduction under pressure of a fluid for food or beverage preparation. The
membrane thus protrudes from the chamber, before being elastically or
plastically
deformed, to engage the opening means.
The opening formed in a bottom end of the chamber can have
.. an area of about 600 mm2 while the part of the membrane which covers this
opening has a developed surface area of more than 750 mm2.
The fastening means can comprise an adhesive seal band.
The membrane can be formed from a flat sheet having a
periphery of greater length than a periphery of the rim which surrounds the
opening, the length of the periphery of the membrane in excess compared to the
length of the periphery of the opening rim being evenly distributed along said
periphery of the opening rim.
The opening formed in the bottom end of the chamber can be
substantially circular, and the membrane can form a dome over the opening
formed in the bottom end of the chamber when a pressure is established in the
chamber (10) greater than the pressure outside the chamber.
The part of the membrane which covers the opening formed in
the bottom end of the chamber can comprise folds so as to be substantially
flat
when the pressures on each side of the membrane are balanced. The membrane
can be at least in part unfolded under the effect of a pressure established in
the
chamber.
One of the difficulties in implementing the invention is the way
to arrange the membrane on an opening of smaller dimensions, and to fasten the
membrane periphery to a fastening area of smaller dimensions such as a rim
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surrounding the opening. Use of an adhesive seal band such as a heat seal
lacquer
makes it possible to fasten an edge of the membrane to such rim even if the
periphery of the membrane is of greater length than a periphery of the rim
which
surrounds the opening. The adhesive seal band material can be chosen from
known materials used in the food industry.
For example, small folds are created at the periphery of the
membrane to reduce its apparent length. The heat seal lacquer band conforms to
the small irregularities formed by the folds at the periphery of the membrane
to
provide fluid-tight sealing between the membrane and the body of the capsule.
If the membrane is fastened to the body by a circular adhesive
seal band it will tend to adopt a dome shape inside the chamber of the
capsule. To
maximise the volume of the chamber the so-configured membrane can be
flattened by creating folds which are unfolded when a high pressure is
established
inside the chamber.
The opening means can comprise (or be constituted by) a plate
having an upper surface facing the membrane, and the upper surface forms or
carries sharp elements. The sharp elements can be pyramids or truncated
pyramids.
A plate having an upper surface carrying truncated pyramids or
other sharp puncturing elements provides an advantageous configuration because
such a surface acts as a pressure-spreading means and has the effect of
allowing
the pressure of the fluid to rise sufficiently inside the capsule before
puncturing
(and opening) of the membrane occurs. In cooperation with the membrane, it
provides a filter function to avoid ingredient such as ground roasted coffee
being
delivered with the prepared beverage.
The part of the membrane which covers the opening formed in the bottom end of
the chamber can have a surface area of more than 60% of the developed surface
area of the plate.
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Such configuration allows the membrane to correctly engage the
opening means, it allows the membrane to correctly conform to the shape of
said
opening means and it provides an efficient cooperation between the membrane
and the opening means to provide a filter function.
The membrane is for example made of aluminium, or of a
laminate structure comprising an aluminium foil and a polymer layer. .
Alternatively, the membrane is for example made of plastics with a metallic
covering. The membrane can comprise pre-weakened spots.
The invention makes it possible to use very stiff (with low or no
elasticity) membranes while a correct engagement of the membrane with the
opening means can be reliably obtained.
The material of which the chamber is formed can be at least one
of aluminium, aluminium/plastics composite, aluminium/plastics/paper
composite,
and plastics in a single layer or in a multilayer form.
The ingredient contained in the chamber can comprise ground
roasted coffee to be extracted into water vapour and/or hot liquid water or
comprises a soluble ingredient or mix of soluble ingredients for preparation
of a
beverage such as instant coffee, hot chocolate, or a soup or other dehydrated
edible product to be dissolved into hot or cold water or milk.
Brief description of the drawings
Additional features and advantages of the present invention are
described in, and will be apparent from the description of the presently
preferred
embodiments which are set out below with reference to the drawings in which:
Figure 1 is a schematic perspective view in cross-section of a
capsule for food or beverage preparation according to the prior art;
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Figure 2 is a schematic perspective view in cross-section of a
capsule for food or beverage preparation according to an example embodiment of
the invention;
Figure 3 is a schematic perspective view of a pyramid plate
which constitutes opening means that can be used in a capsule according to the
invention;
Figures 4a to 4c are schematic partial cross-section views of a
capsule which illustrate the behaviour of a membrane of a capsule according to
the prior art;
Figures 5a and 5b illustrate on similar views as Figure 4a two
alternative embodiments of a capsule according to the invention;
Figures Sc and 5d illustrate on a similar view to those of Figures
4b and 4c the behaviour of a membrane of a capsule according to the invention
when a high pressure is established inside the capsule chamber.
Detailed description of the invention
The capsule 3. of Figure 3. comprises a capsule body 2 made of
capsule walls 3. In the represented embodiment, the capsule body walls 3 have
a
substantially frusto-conical shape
The capsule walls 3 can be made of different materials. They can
be made of aluminium, aluminium/plastics composite,
or
aluminium/plastics/paper composite. They can be made of a rigid or semi-rigid
thermoplastics such as a polypropylene or polyethylene. Plastics can be in a
single
layer or in a multilayer form. The capsule body can for example also be made
of
any suitable type of impermeable material such as coated paper, coated
cardboard,
other materials containing cellulosic fibres, or starch for instance, metal or
alloy,
glass, synthetic or natural rubber or elastomer, or a combination thereof.
Preferably, materials will be chosen from cost-effective and ecologic
material, e.g.
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biodegradable material, having barrier properties, preferably at least against
moisture and oxygen
Depending on the material used, the manufacturing process can
be thermoforming or injection. It can also involve in-mould labelling, for
instance
in order to provide the capsule with specific barrier properties by using a
film label
with moisture and oxygen barrier properties. Such an in-mould labelling
process
for making a capsule is generally described in the applicant's European patent
publication EP 2559636 Al. The moisture and oxygen barrier properties of the
container walls can be achieved with any kind of suitable material such as
barrier
thermoplastics films having single or multiple layers, or aluminium, or paper,
or a
combination thereof. The capsule body walls 3 comprise upper and lower
openings.
The upper opening of the capsule body is closed by an upper
injection wall 4 forming the top face 5. The upper injection wall 4 can be
welded
on upper peripheral edges 6 of the capsule body walls 3.
The capsule 3. further comprises a bottom wall 7 having a
dispensing opening 8. It further comprises a pierceable membrane 9, for
example
made of aluminium. The membrane 9 is preferably made of a laminate structure
comprising an aluminium foil and at least a polymer layer. More particularly,
the
membrane 9 can comprise a sealing layer that makes it possible to fasten the
aluminium foil to the body of the capsule (for example made of plastics).
Optionally, a top layer of protective lacquer can be provided to prevent the
aluminium foil from damages caused by the aggressive powder particles of
ingredient contained inside the capsule. The membrane 9 is fastened to the
capsule body 2. A chamber 10 is thus formed within the body 2, delimited by
the
body walls 3, the injection wall 4, and the membrane 9.
The membrane 9 is fastened to the body 2 by an adhesive seal
band 11. The adhesive seal band 11 provides sealing between the body 2 and the
membrane 9.
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More particularly, the chamber 10 is closed at its bottom end by
the membrane 9, the bottom end of the chamber 10 comprising an opening closed
by said membrane 9. The opening at the bottom end of the chamber 10 is
surrounded by a rim 12. The rim 12 extends in a plane parallel to the top face
5 of
the capsule, and provides a flat surface for fastening the membrane 9. The
adhesive seal band 11 is interposed between said rim 12 and a periphery of the
membrane 9.
The capsule 1of the represented example embodiment further
comprises a rigid distributor wall 13 that is located between said injection
wall 4
and a capsule lower compartment 14.
Preferably, the ingredient contained in the capsule is located in the
interior compartment 14, i.e. in the portion of the capsule chamber 10 which
is
between the distributor wall 13 and the bottom membrane 9.
However, it is also possible to dispose the same ingredient throughout
the whole volume of the chamber 10, or alternatively, two different
ingredients
can be separated from one another by the distributor wall 13.
The distributor wall 13 comprises through-holes. Their diameter is
appropriately chosen depending on the type of ingredient contained in the
capsule
and on the corresponding type of product preparation. If the distributor wall
comprises a single hole, the flow of fluid through said hole will create a
single jet,
with a powerful mixing effect. This configuration is preferably chosen in case
the
ingredient contained in the capsule is a soluble powder, which requires a
powerful
swirling movement of the water injected therein, so as to improve the
dissolution
of the powder with the water. Alternatively, for example if the ingredient
contained in the capsule compartment is ground roasted coffee, the distributor
wall 13 comprises a plurality of holes, distributed evenly across its surface
to
ensure proper wetting of the coffee bed contained between the distributor wall
29
and the bottom wall 32 of the capsule.
The diameter of the holes is preferably less than the smallest particles
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of the ingredient, but it is sufficient to ensure a proper flow of water
through the
rigid distributor wall 13. The diameter can for example be comprised typically
between 10 microns and 3mm, preferably between 100 microns and 1 mm.
Between the membrane 9 and the bottom wall 7, opening
means 15 are provided. The opening means 15 has the general shape of a plate,
the upper face of said plate facing the membrane 9 and being disposed inside
the
capsule body 2 in the vicinity of the membrane 9. The upper face of the plate
of
the opening means forms sharp elements adapted to pierce or tear the membrane
9 when fluid pressure inside the capsule compartment increases thus engaging
the
membrane with the opening means 15 and pressing said membrane against said
opening means.
Figure 2 represents an example embodiment of a capsule
according to the invention, shown on a similar view to Figure 1.
The general configuration of the capsule of Figure 2 is identical
to the general configuration of the capsule of Figure 1, except for the
membrane 9.
The above detailed description of the capsule of Figure 1 is thus applicable
to the
capsule of Figure 2, with the following differences.
The membrane 9 of the prior-art capsule of Figure 1 is usually
made of a flat aluminium foil (or a foil of an adapted material) cut to the
right
dimensions to cover the opening at the bottom end of the chamber 10 and to
rest
on the rim 12 to which it is fastened by fastening means such as an adhesive
seal
band (e.g. made of a heat seal lacquer) which forms a seal between the
membrane
9 and the rim 12. When the membrane 9 is not subject to a pressure difference
between the inside and the outside of the chamber, it is substantially flat.
According to the present invention and as shown in Figure 2, the
part of the membrane which is surrounded by the seal has a developed surface
area comprised between 110% and 140% of the area of a flat surface surrounded
by said seal. In other words, the part of the membrane surrounded by the
fastening means has a surface area which is 10% to 40% greater that the
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corresponding surface area of the flat membrane according to the prior-art
shown
in Figure 1. This implies that the part of the membrane 9 surrounded by the
fastening means cannot be flat. If the seal formed by the adhesive seal band
11 is
substantially circular, this part of the membrane 9 can have the shape of a
dome.
As in the prior-art, the membrane 9 can be obtained in a flat
aluminium (or other adapted material) foil. For example, if the rim 12 where
the
membrane is fastened is circular, a circular membrane 9 of greater diameter
than
the diameter of the rim 12 can be used. The periphery of the membrane 9 is
thus
of greater length than the periphery of the rim 12 which surrounds the
opening.
The excess length of the membrane periphery can be evenly distributed along
the
periphery of the rim 12. In particular, small folds can be made at the
periphery of
the membrane 9 to arrange the membrane 9 on the rim 12 having a smaller
periphery.
Thanks to the use of an adhesive seal band such as a heat seal
lacquer as fastening means, a fluid-tight seal can be provided despite the
surface
irregularities caused by the folds at the periphery of the membrane 9.
As hereafter described with reference to Figures 4a to 5d, the
greater surface area of membrane compared to a capsule according to the prior
art will help the membrane 9 to correctly engage the opening means 15 and to
conform to the same when a pressure higher than atmospheric pressure is
established in the chamber 10 when fluid for food or beverage preparation is
injected into the chamber 10.
Figure 3 is a detailed perspective view of an example
embodiment of the opening means 15, corresponding to the opening means used
in the capsule of Figure 1. The upper face the opening means 15 is shown in
Figure
2. According to this embodiment the opening means 15 for opening the
membrane 9 consist of a disc with recessed and raised elements 16. The
recessed
and raised elements 16 have a pyramid-shape (more precisely a slightly
truncated
pyramid shape). In other embodiment, the recessed and raised elements have any
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other geometry adapted to open the membrane, such as a cone shape. Smaller
raised elements 17 are also arranged in spaces 18 between the pyramidal raised
elements 16.
The plate comprises holes preferably formed in the spaces 18
between the pyramidal raised elements 16 (e.g. at the top of said smaller
raised
elements) so as to let the product formed by dissolution or extraction inside
the
compartment 14 out towards a consumer's cup when the membrane 9 is opened.
As the membrane engages and is pressed against the upper face
of the opening means, the membrane has also a filter function for the prepared
beverage.
The membrane has to correctly engage with the opening means,
and in particular it has to be deformed and stretched to conform to the
pyramid
surfaces (or the surfaces of other opening elements) to provide, in a
reproducible
way, a regular opening such as holes or tears evenly distributed over the
surface of
the membrane, and also to provide a filter function to avoid particles of
ingredient
being delivered with the food or beverage product. To enhance reproducibility
of
the membrane opening, the membrane can comprise pre-weakened spots. The
pre-weakened spots can advantageously be placed to match the raised elements
of the opening means when the membrane engages said opening means.
Figures 4a, 4b and 4c illustrate the behaviour of a membrane of
a capsule according to the prior art when a food or beverage product is
produced.
Figure 4a represents the bottom end portion of a capsule for
food or beverage preparation, before injection of fluid inside the chamber 10.
The
membrane 9 is fastened to rim 12 formed by the walls 3 of the body 2 by the
adhesive seal band 11. As the pressure is balanced between the interior of the
capsule (chamber 10) and the exterior of the capsule, no force due to a
pressure
difference is applied to the membrane 9. In this state, the exterior surface
of
membrane 9 (face of the membrane outside the chamber 10) faces the opening
means 15 in the vicinity of an upper face of said opening means 15.
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In Figure 4b, fluid, typically water and/or water vapour is
introduced under pressure (i.e. above atmospheric pressure) into the chamber
10
formed within the capsule body 2. The pressure rises inside the chamber 10.
The
pressure is applied to the body walls 3 and to the membrane 10. More
particularly,
the pressure is applied to the part of the membrane 9 which closes the opening
surrounded by the rim 12. The pressure difference between the interior of the
capsule (chamber 10) and the exterior of the capsule, in particular under the
membrane 9, generates a force distributed over the membrane surface area which
closes the opening surrounded by the rim 12. This force pushes the membrane 9
in
a direction from inside to outside the chamber 10. The membrane 9 engages the
opening means 15. As shown in figure 3b, because the membrane is made of a
stiff
material such as aluminium, the deformation of the membrane 9 is limited. More
particularly, the increase of the membrane surface area, i.e. the ability of
the
membrane to be elongated before it ruptures, is limited. The membrane thus
conforms only to the top part of some of the raised elements of the opening
means.
The pressure rises in the chamber 10 with introduction of fluid
until it reaches a so-called opening pressure. With the pressure rise inside
the
chamber the membrane is pressed against the opening means by the force
generated by the pressure difference between the pressure inside the chamber
10
and the atmospheric pressure outside said chamber 10. When the opening
pressure is reached, the membrane opens (i.e. is pierced, cut, or torn) as
shown in
Figure 3c thanks to the raised elements 16 of the opening means 15 that create
a
mechanical lever effect onto the membrane, hence a mechanical stress in the
membrane material until the latter reaches its mechanical failure point and
tears
or more generally breaks. This breaking of the material does not necessarily
need
to be in a plane perpendicular to the general plane of the membrane, but can
also
be in any other direction, and not necessarily throughout the whole thickness
of
the material, as long as a passage is created between the inside of the
capsule and
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the outside, so as to allow product to flow from inside the capsule towards
the
outside. The food or beverage product obtained flows through the membrane 9
and the opening means 15 to be delivered by the dispensing opening 8.
However, because the conformation of the membrane to the
raised element is limited before it is opened, the membrane can have an
irregular
opening: the opening can be irregularly distributed on the membrane surface in
contact with the opening means, the membrane can be ruptured before it
conforms to the opening means (so that the pressure drops and the beverage
flows through an opening of the membrane having an undesired shape). The
opening of the membrane can also be different from one capsule to another. The
filter function of the membrane 9 in cooperation with the opening means can
change from one capsule to another. Particles of the ingredient contained in
the
compartment 14 (or generally speaking in the chamber 10) can pass through the
membrane and opening means. For coffee preparation, this can lead to coffee
having an unpleasant taste or texture.
The bad reproducibility of the opening of the membrane and its
filter function from one capsule to another can change the quality or the
taste of
the prepared food product or beverage, because the pressure inside the chamber
during the beverage preparation can change from one capsule to another, and
because the filter function of the membrane and opening means can be modified.
By way of comparison, Figures 5a, 5b, Sc and 5d illustrate the
behaviour of a membrane of a capsule according to the invention when a food or
beverage product is produced.
More particularly, Figures 5a and 5b illustrate on similar views to
Figure 4a two alternative embodiments of a capsule according to the invention,
and Figures Sc and 5d illustrate on a similar view to those of Figures 4b and
4c the
behaviour of a membrane of a capsule according to the invention (e.g.
according
to the embodiments of Figures 5a and 5b) when a high pressure is established
inside the capsule chamber.
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Figure 5a represents the bottom end portion of a capsule for
food or beverage preparation, before injection of fluid into the chamber 10.
The
embodiment of figure 5a corresponds to the embodiment of Figure 2. The
membrane 9 has a part surrounded by the adhesive seal band 11 of greater
dimensions than the flat surface surrounded by said adhesive seal band (i.e.
in the
present case of greater dimensions than the opening at the bottom end of the
chamber 10). The membrane 9 forms a dome over said opening.
Compared to the embodiment of Figure 5a, in the embodiment
of Figure 5b the membrane is folded in the initial state (before preparation
of the
food or beverage product), so as to have an apparent flat shape over the
opening
at the bottom end of the chamber 10. The folds of the membrane can have a
determined or erratic configuration. The apparent flat shape of the membrane 9
increases the space available for the ingredient inside the chamber 10.
In Figure 5c, as in Figure 4b, a fluid such as water and/or water
vapour is introduced under pressure (i.e. above atmospheric pressure) into the
chamber 10 formed within the capsule body 2. The pressure rises inside the
chamber 10. The pressure is applied to the body walls 3 and to the membrane
10.
The pressure difference between the interior of the capsule (chamber 10) and
the
exterior of the capsule, in particular under the membrane 9, generates a force
distributed over the membrane surface which closes the opening surrounded by
the rim 12. This force pushes the membrane 9 in a direction from inside to
outside
the chamber 10. The membrane 9 thus engages the opening means 15.
Thanks to the configuration of the membrane in a capsule
according to the present invention, extra surface is provided for conformation
of
the membrane to the shape of the raised elements 17 of the opening means (or,
generally speaking, for conformation of the membrane to the shape of the
opening
means). Compared to the membrane of a prior-art capsule, the membrane 9 of a
capsule according to the invention can enter deeper into the spaces 18 between
the pyramidal raised elements 16. It covers a greater percentage of the
surface of
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the face of the opening means facing the membrane. For example, the membrane
9 can be dimensioned to obtain a coverage of more than 60%, and preferably
more than 70% of this surface before said membrane opens.
With a capsule according to the present invention, the
conformation of the membrane to the shape of the opening means is more regular
over the whole surface of the membrane (or, more precisely, over the whole
surface of the part of the membrane facing the opening means).
As shown in Figure 5d, the pressure rises in the chamber 10 with
introduction of fluid until it reaches the opening pressure. The membrane is
pressed against the opening means by the force generated by the pressure
difference between the pressure inside the chamber 10 and the atmospheric
pressure outside said chamber 10. When the opening pressure is reached, the
membrane opens (i.e. is pierced, cut, or torn) as shown in Figure 5c thanks to
the
sharp design of raised elements 16 of the opening means 15. The food or
beverage
product obtained flows through the membrane 9 and the opening means 15, and
is correctly filtered by these means to avoid too many particles of ingredient
being
present in the product delivered by the dispensing opening 8.
Thanks to the better conformation of the membrane to the
shape of the opening means, a regular opening can be obtained over the whole
surface of the membrane in contact with the opening means. In the represented
example embodiment, the membrane after opening presents evenly distributed
openings formed by the top of each pyramidal opening element. This also
results
in a constant and thus more predictable pressure inside the chamber 10 when a
food or beverage is prepared from one capsule to another. An effective filter
function is provided by the cooperation between the membrane and the opening
means. Finally, a constant quality and taste of the product is provided.
It should be understood that various changes and modifications
to the presently preferred embodiments described herein will be apparent to
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those skilled in the art. Such changes and modifications can be made without
departing from the spirit and scope of the present invention and without
diminishing its attendant advantages. It is therefore intended that such
changes
and modifications be covered by the appended claims.
18
