Note: Descriptions are shown in the official language in which they were submitted.
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PORTION CAPSULE
The invention relates to the field of systems for preparing drinks by way of a
fluid which
is introduced into a drinks capsule. In particular, it relates to a portion
capsule which contains a
soluble foodstuff substance, from which a drink or a drink constituent can be
prepared by way of
inj ecting water.
Amongst the systems for preparing drinks, so-called coffee capsule systems
(they also
exist in variants for preparing tea) are known, concerning which generally hot
water mostly
under pressure is introduced into a capsule, in order to prepare a coffee
drink or tea drink by way
of extraction. The capsule is often pierced at the one side (injection side)
for the introduction of
the hot water. Different possibilities are known for leading out the brewed
drink, generally at the
other side of the capsule (the extraction side). On the one hand there are
systems, concerning
which a piercing by way of suitable perforation spikes is also envisaged at
the extraction side.
On the other hand, systems are known, concerning which an extraction-side
delimitation of the
capsule under the internal pressure is pierced or torn during the brewing
process, for which a
capsule-external (present in the brewing chamber of the respective coffee
machine) or capsule-
internal means can be present. Finally, there are also capsules which are
already opened,
concerning which therefore no capsule wall / membrane needs to be pierced or
torn, in order to
lead out the drink.
Amongst other things, in order to prevent coffee powder (or tea leaves) from
undesirably
getting into the brewed drink, capsules concerning which a filter element is
arranged in the
inside of the capsule have become known, said filter element separating an
extraction material
region from a collecting region and being fluid-permeable in a suitable
manner, for example by
way of it comprising a plurality of filter openings.
Examples of portion capsules with such filter elements are to be found for
example in EP
1 344 722 as well as in WO 2010/085824. The latter publication shows the
filter element with
struts which extend radially from an outer frame towards the middle and herein
become thinner
towards the middle. These are to reinforce the filter element. Such a
reinforcement can be
displaced, in particular with regard to the preparation of brewed drinks under
pressure, as is the
case for example with espresso and other coffee with a so-called "crema". With
such brewing,
the inner pressure of the capsule for the most part bears on the filter
element which can therefore
be subjected to a mechanical deformation.
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It is the object of the present invention to provide a filter element for a
portion capsule as
well as a respective portion capsule. The filter element is to be mechanically
stable as well as
inexpensive and simple in manufacture.
According to an aspect of the invention, a filter element for a portion
capsule is provided.
This can be inserted into a base element which is designed for example in a
beaker-like manner
and which together with a capsule cover which is fastened to the base element
after the insertion
of the filter element defines an outer capsule wall. The filter element is
designed such that it
divides the capsule interior between an extraction material region and a
collecting region which
is formed between the filter element and the outer capsule wall. The filter
element forms a filter
plate and a two-dimensional frame of struts which run along the filter plate
and meet one
another at an angle.
This approach according to the invention is based on the recognition that a
two-
dimension frame generally entails more stability than a system of struts which
merely run
radially from the outside to the inside. The reason for this can be the fact
that under real
conditions, the capsule inner pressure is not strictly constant with regard to
time or location, and
for this reason bending oscillations of the filter plate can also arise. A two-
dimensional frame
can accommodate such in a comparatively better manner. The invention however
is not
dependent on a certain explanation of this finding.
The struts can have a cross section which reduces radially outwards (i.e. have
a reducing
cross- sectional area).
Such a reduction of the cross section of the struts can be a reduction of the
extension
perpendicular to the plane of the filter plane. The reduction of the cross
section can be
continuous towards the outside. However, one also does not rule out the cross
section for
example also being regionally constant as a function of the radial position;
but on average the
cross section further to the outside with regard to a centre of the filter
plate will be smaller than
further to the inside. It is also possible for the frame of the struts to
completely run out to the
outside, i.e. for the struts to not completely reach the outer edge of the
filter element.
This preferred embodiment with an outwardly reducing cross section is based on
the
insight that given a subjection to pressure in the capsule interior, the
deformation is greatest in a
central region of the filter element. Furthermore, generally less material is
necessary for
geometric reasons if the struts at the inside have a larger cross section than
at the outside, in
comparison to the opposite approach.
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In a group of embodiments, the filter element comprises a central element.
This can form
for example a projection to the capsule interior (towards the extraction
material region); such a
projection can be essentially conical. The frame of the struts then preferably
runs up to the
central element, i.e. the innermost struts are connected to the central
element, in order to stabilise
this. The central element can define for example a free space for an
extraction-side piercing
spike.
A central element, up to which the frame of the strut runs, in particular can
be designed
as a bulging to the side, on which the struts are arranged (thus for example
towards the capsule
interior). By way of the central element in this embodiment being formed by a
bulging, a cavity-
like extension results towards the other side (thus for example towards the
collecting region).
Such a bulge-like or dome-like design of the central element is particularly
favourable with
regard to the ratio between the mechanical stability on the one hand and the
material
consumption on the other hand.
The frame of struts in particular on a path from the inside to the outside,
formed by the
struts, can form several branchings so that struts which are arranged at least
in a central region
are each stabilised to the sides at both ends.
The struts which form the frame therefore, apart from in the middle where for
example
they meet the central element, can yet be branched at (in each case) one
further location - they
are therefore different to the struts which run in a radiant manner from the
middle to the edge
and are additionally stabilised by the branchings.
In particular, the frame of the struts can form a honeycomb structure. Given
such a
structure, the ratio of the material which is to be applied to the created
stability is particularly
favourable.
The filter plate can be provided with filter openings in a manner known per
se, these
being regularly or irregularly distributed over the filter plate and
permitting the fluid to be led
through. The size of the filter openings can be such that a passage of
extraction material is
prevented. One also does not rule out the filter openings being spanned by a
for example fabric-
like filter material, in order to prevent the passage of extraction material
through the filter
openings.
In particular, the struts can be arranged on the side of the filter element to
the capsule
interior, i.e. towards the extraction material region. At the rear side, the
filter element can
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comprise a plurality of spacers which help to prevent the filter plate being
pressed against the
outer capsule wall given a high pressure of the capsule interior.
The filter element can be designed in a beaker-like manner in the manner known
per se,
by way of it comprising a peripheral side wall which connects onto the filter
plate at the outer
side, and specifically in particular at the extraction material side, so that
a filter beaker volume
forms part of the extraction material region. A peripheral side wall can form
a peripheral flange
which projects radially outwards and which can serve for the fastening of the
filter element in a
capsule base element (for example capsule beaker).
In an alternative embodiment, the filter element as a whole can be roughly
disc-like,
without a peripheral side wall. Such a filter element is suitable for example
for being fastened to
a shoulder of the capsule base element (for example capsule beaker), for
example by way of
welding or another material-fit connection. Alternatively, such a disc-like
filter element can also
be positively - for example by way of clicking into a peripheral groove of the
capsule base
element - and/or non-positively received in the capsule.
The invention also relates to a portion capsule with such a filter element.
The filter
elements are arranged within an outer capsule wall of the portion capsule.
Such can be formed
for example by a beaker-like base element and a cover which is fastened
thereto. The base
element generally defines a capsule base and a capsule side wall. The filter
element is located
between the extraction material region which is filled with an extraction
material, in particular
coffee power, and the capsule base or between the extraction material region
and the capsule
cover. The filter element can be fastened to the base element or possibly to
the cover, or it can
also be merely inserted into the base element and be stabilised relative to
the base element for
example by the extraction material. A possible fastening of the filter element
to the base element
or cover can be with a positive, non-positive and/or material fit. Fastenings
of filter elements in a
capsule beaker are known per se and the present invention is independent of
the manner in
which the filter element is fastened.
Embodiment examples of the invention are described hereinafter by way of
figures.
There are shown in:
Fig. 1 a schematic sectioned representation of a portion capsule with
the filter element;
Fig. 2 a view of a filter element from the extraction side;
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Fig. 3 a view of the filter element represented reduced in size from
the opposite side
(collecting region side);
Fig. 4 a view of the filter element of Fig. 2 and 3 from above;
Fig. 5 a representation of a filter element sectioned along the plane V-
V in Fig. 4;
Fig. 6 a representation of the filter element sectioned along the plane
VI-VI in Fig. 4;
and
Fig. 7 a view of an alternative filter element from the extraction
material side.
Different scales have been used in the Figures 2, 3, 7 as well as 4-6
respectively. In the
figures, the same reference numerals denote equal or analogous elements.
The capsule 1 according to Figure 1 comprises a base element in the form of a
beaker 11
(with axis 20) and a cover 12 which is fastened thereon along a peripheral
flange 13, these
together forming an outer capsule wall and defining a capsule interior. The
beaker 11 as is
known per se forms a capsule base 14 which here is slightly arched and a
peripheral side wall
15.
The beaker and cover are manufactured of plastic in a manner known per se;
however
the invention can also be applied to capsules of other materials, for example
aluminium. The
fastening of the cover to the beaker has likewise being carried out in a known
manner, for
example by way of ultrasound welding or possibly also bonding.
A filter element 2 which is inserted into the beaker is present in the capsule
interior, the
characteristics of which will be described in more detail hereinafter. In the
represented
embodiment example, the beaker is fastened to a shoulder 16 which is formed by
the peripheral
side wall 15, for example by way of welding, i.e. by way of material-fit
connection. Other
fastening methods, amongst others positive fit and non-positive fit
connections would likewise
be possible.
The filter element separates an extraction material region 5 which will be
filled with
extraction material, from a collecting region 6. In the presented embodiment
example, the filter
element 2 is arranged in the proximity of the capsule base 14, and the
collecting region 6 is
located on the side of the capsule base. The injection of the water into the
capsule for the
brewing process is then also generally effected from the cover side. The
reverse arrangement
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would also be conceivable, concerning which the water is injected from the
base and the filter
element is arranged at the cover side.
Figure 1 schematically and in a dashed manner also represents an optional
distributing
element 3 which is likewise inserted into the capsule and which delimits the
extraction material
region 5 to the injection side and between itself and the capsule cover 12 (or
in the reverse
arrangement between itself and the capsule base) defines a distributing region
7.
The filter element 2 as well as possibly the distributing element 3 is/are
permeable to
fluid in a suitable manner, and specifically such that the extraction material
cannot pass through.
The manner of functioning of such filter elements as well as of distributing
elements is
described for example in EP 1 792 850, to which publication reference is made
in regard of this.
An embodiment of the filter element is represented in Figures 2-6. The filter
element 2
forms a filter plate 21 with a plurality of filter openings 22 which run
through it and which in the
represented embodiment example are designed widening slightly in the direction
away from the
extraction material region (towards the collecting region side), in order to
prevent blockages by
way of small grains of coffee. A plurality of spacers 29 is present at the
collecting region side,
and these supplementarily to the subsequently described reinforcing frame
prevent the filter
plate 21 from being pressed again the capsule base 14 given a high capsule
interior pressure and
thus can prevent a flow in radial directions in the collecting region.
In the represented embodiment example, the filter element as a whole is
designed in a
beaker-like manner, with a peripheral side wall 23 which connects onto the
filter plate 21 at the
outer side and which together with the filter plate defines a filter beaker
volume which is part of
the extraction material region. A peripheral edge 24 which projects outwards
in a flange-like
manner and which in the represented embodiment example serves for the
fastening of the filter
element 2 in the capsule beaker 11 is formed on the peripheral side wall 23 at
the outer side.
A central element 25 which has the shape of an inwardly i.e. towards the
extraction
material region, projecting projection is formed in the centre of the filter
plate 21. This
projection which forms the central element 25 is essentially conical with a
plurality of
projections.
At the extraction material side of the filter plate 21, the filter element
comprises a frame
of struts 26 which form a hexagonal structure, i.e. a honeycomb structure. The
nature of such a
structure is that the individual struts 26 are equally long and meet at
branchings 27 so that three
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struts are adjacent to each branching 27. Such a honeycomb structure forms a
particularly stable
two-dimensional frame.
A further characteristic of honeycomb structures and other stable two-
dimensional frame
structures is that a plurality of branchings is always present on an arbitrary
path along the struts
from the very radial outside to the very radial inside, i.e. in the frame
there are no struts which
reach from the very outside to the very inside without them also being
supported in lateral
directions by a plurality of branchings 27. The same applies to an arbitrary
path in the peripheral
direction, i.e. no path of struts around the complete periphery, on which path
the struts do not
branch at several locations, is to be found in the frame.
The frame connects onto the central element at the radially inner side
(direction details
such as "radially" or "in the circumferential direction" or also "centrally"
in this text, inasmuch
as not explicitly stated otherwise, always relates to the axis 20 of the
capsule).
The strength of the struts (i.e. the cross-sectional area perpendicular to the
respective
running direction of the struts) reduces radially outwards. This is realised
by way of the
extension of the struts in the dimension perpendicular to the filter plate
being gradually reduced
radially outwards, whereas the width, i.e. the extension perpendicular to the
running direction of
the respective strut and parallel to the filter plate is constant. The
strength of the struts in the
represented embodiment tends to zero radially at the very outside, which can
be seen particularly
well in Figure 5 and 6. However, it would also be possible for the strength of
the struts not to be
completely zero at the very radial outside and for the struts to reach up to
the peripheral side
wall 23.
Figure 7 shows an alternative embodiment of the filter element 2 which differs
from that
of Figure 2 -6 in particular in that it comprises no peripheral side wall and
is therefore not
designed in a beaker-like manner, but as a whole is disc-shaped. The edge
region 28 of the filter
element at the radial outer side connects onto the filter plate 21 with the
frame. It can comprise a
peripheral rib at the outer side (i.e. the side towards the collecting region,
in Fig. 7 the lower side
and therefore not visible), said rib serving as an energy director in an
ultrasound welding
method. The filter element can thus be welded onto a shoulder which is formed
by the capsule
base element which for example is designed in a somewhat more pronounced
manner than the
shoulder 16 which is schematically represented in Fig. 1.
The central element, the frame of the struts 26 as well as the filter plate 21
as a whole in
the embodiment of Fig. 7 is functionally equal to the aforedescribed
embodiment.
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Further embodiments are possible, amongst other things also with other capsule
shapes.
It would also be possible to provide the frame of struts at the outer side,
i.e. at the side of
the filter plate 21 towards the collecting region.
Example: Numerical simulations were carried out with a filter element
according to
Figures 2-6. The filter element being subjected to a temperature of 100 C at a
pressure of 12 bar
on the inner side was simulated. For comparison, the same simulation was
carried out on a filter
element which does not comprise the frame of struts, but which is otherwise
designed in an
identical manner. It was found that given both comparable filter plates, the
deformation is
greatest in a central region, in particular at the location of the central
element and in its direct
environment. The maximal deformation with the filter element according to the
invention
however is reduced by a factor of approx 3 in comparison to the filter element
which is not
designed according to the invention
Date Recue/Date Received 2020-09-28
