Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Coffee Capsule
Technical Field
The invention relates to capsule which under pressure in expresso machines is
suitable for extraction of coffee and which may contain roasted and ground
coffee.
The capsule comprises a truncated cone-shaped capsule body of
thermoformed plastic having a side wall. The wider end of the side wall
defines
an outlet side of the capsule and the narrower end of the side wall defines an
inlet side of the capsule. The capsule body further has an outwardly directed
circumferential first flange on the wider end of the side wall providing a
sealing
area towards a brewing chamber of an expresso machine; and a circular inlet
opening on the narrower end of the conical side wall. A destructible outlet
sealing membrane is attached to the first flange and closes the outlet side of
the capsule body. A inlet sealing membrane closes the inlet opening of the
capsule body and is attached to the inside of the capsule body.
Prior Art
For more than 20 years, the company Nestle SA has been successfully selling
portioned packages containing roasted and ground coffee, with which coffee
can be extracted under pressure in espresso machines. These portioned
packages are known in several shapes; it is however the conical capsules
which have proven particularly successful on the market. The expresso
machines for these conical capsules comprise a so-called brewing chamber
largely corresponding to the shape of the capsules. The capsules are held in
the machine in a clamped and sealed manner, whereupon several water
injection needles or tear-open tips penetrate into the capsule at its narrower
end. When water as an extraction fluid is getting into the capsule under
pressure, a sealing membrane on the wider end of the capsule is destroyed in
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a patterned manner at several locations by a counter-pressure plate in the
machine and the extraction fluid can thus practically exit through a sieve
leaving the ground coffee within the capsule.
Various patents directed to these capsules have expired in the meantime, and
capsules in competition have arrived on the market. These are designed such
that they can be used compatibly with the already existing expresso machines.
The compatible capsules which are present on the market today are of plastic
for ecological as well as economic reasons instead of the original aluminium
capsules. This means that the capsules must be designed such that injection
needles belonging to the machine do not come into contact with the plastic of
the capsule, because otherwise the hot injection needles or tear-open tips
would cause melting of the plastic material, which would lead to a bonding of
the injection needles and thus would result in the exit openings of these
needles becoming blocked. Such a plastic capsule is described e.g. in
EP2712824.
Also, the tips heated by the hot water would soften the plastic and this
plastic
would form around the tip in a closing manner and handicap the correct entry
of water. The plastic residues remaining on the tips moreover lead to a
blunting of the tips and these would no longer function correctly over time.
Accordingly, these capsules are built smaller in axial direction as the
original
capsules of the company Nestle SA and/or have a recessed bottom part.
Thereby significantly more water gets into the brewing chamber of the
machine and may flow around the capsule on extraction. Only when the
remaining space between the capsule and the brewing chamber is completely
filled, does the water forcibly go only into the plastic capsule. However,
this is
not the case and a need of a greater sealing effect between the brewing
chamber of the machine and the inserted plastic capsule exists.
Disadvantageous to the shorter plastic capsules is also the smaller volumetric
capacity for holding ground coffee and the necessary greater sealing effect.
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Therefore, there is need for plastic capsules having the same axial length of
the original aluminium capsules allowing the injection needles to penetrate
into the capsule but still avoiding the above problems of the hot injection
needles melting the plastic.
From EP2210827 a conical capsule optionally made of plastic with a similar
form as the original aluminium capsules is known. The capsule has on its
narrower side a circular inlet opening covered from the inside of the capsule
with a membrane. The membrane is attached to the capsule in a detachable
sealing engagement. When water pressure builds up in a brewing chamber the
detachable sealing membrane deflects and the water is injected into the
capsule. The machines for these capsules however do not have hot injection
needles or tear-open tips penetrating the inlet membrane and the capsule
cannot be used in an expresso machine with hot injection needles or tear-open
tips.
FR2617389 describes another type of capsules for producing e.g. cappuccino
where after brewing the entire content of the capsule is removed by a tube-
like emptying element into a cup. Thereby a membrane attached to the edge
of an opening is pierced by the emptying element approximately the size of
the opening. The emptying element however is not hot and the problem of
softening or melting the plastic of the capsule does not occur.
Summary of the Invention
It is an objective of the invention to provide a capsule compatible with the
well-known Nespresso machines, said capsule being made of plastic and
having approximately the same size and axial length of the original aluminium
capsules allowing the injection needles to penetrate into the capsule. The
above problems of the hot injection needles melting the plastic should be
avoided.
This is achieved by a capsule according to claim 1. Thus, the capsule which
under pressure in expresso machines is suitable for extraction of coffee and
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which may contain roasted and ground coffee, comprises a truncated cone-
shaped capsule body of thermoformed plastic having a conical side wall, the
wider end of the conical side wall defining an outlet side of the capsule and
the
narrower end of the conical side wall defining an inlet side of the capsule;
an
outwardly directed circumferential first flange on the wider end of the side
wall
providing a sealing area towards a brewing chamber of an expresso machine;
and a circular inlet opening on the narrower end of the conical side wall. The
capsule further comprises a destructible outlet sealing membrane being
attached to the first flange and closing the outlet side of the capsule body;
and
a destructible inlet sealing membrane closing the inlet opening of the capsule
body and being attached to the inside of the capsule body. The capsule body
further comprises a circumferential centring ramp at the narrower end of the
conical side wall, which translates into an inwardly directed circumferential
second flange forming the circular inlet opening. The circumferential centring
ramp is designed to align the inlet sealing membrane with the inlet opening
before welding it to the second flange. The inlet sealing membrane has a
diameter larger than the outer diameter of the second flange, such that the
circular edge of the inlet sealing membrane is able to bend upwards along the
centring ramp and at least partially covers the centring ramp when welding it
to the second flange, wherein the upwards bend circular edge forms a heat
protecting layer between a hot sealing tool and the centring ramp during
welding the inlet membrane to the second flange.
Because in the existing expresso machines several injection needles or tear-
open tips are arranged in a widely spaced arrangement the inlet opening of a
capsule with a plastic capsule body must have a size as large as possible in
order to avoid contact with the hot injection means of the machine. On the
other hand the capsule body on its narrower side must still provide a large
enough area for permanently attaching the sealing membrane in an accurate
and efficiently manufacturing process manner. In order to fulfil both criteria
the plastic capsule comprises the inwardly directed circumferential second
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flange, onto which the sealing membrane is welded, and a centring ramp for
correctly positioning the sealing membrane during the manufacturing process.
At the same time the inlet sealing membrane has a diameter larger than the
outer diameter of the second flange. The inlet sealing membrane placed inside
the capsule body during the manufacturing process is typically attached to the
flange by thernno-welding with a sealing tool e.g. in the form of a welding
iron
pressing the sealing membrane onto the flange. Thereby the inlet sealing
membrane with its oversize compared to the outer diameter of the flange (or
inner diameter of the centring ramp) is bend upwards along the centring ramp
and at least partially covers the lower part of the centring ramp. This upward
formed bend of the sealing membrane protects the centring ramp and the
capsule body from the heat of the sealing to e.g. in form of a welding iron
allowing the actual welding ring to be closer to the conical side wall. This
in
turn allows to reduce the size of the inwardly directed flange and thereby
enlarge the size of the inlet opening to avoid contact of the plastic capsule
with the hot injection means of the expresso machine.
With the present invention the diameter of the circular opening can be
designed such that hot injection needles or tear-open tips of the expresso
machine do not touch the plastic capsule body when penetrating into the
capsule.
Further embodiments of the invention are set forth in the dependent claims.
A good performance of the circumferential centring ramp for centring and
bending the inlet sealing membrane has been found with an circumferential
centring ramp having an off-axis angle to the longitudinal axis of the capsule
of 20 to 50 degrees, preferably 35 to 40 degrees.
In some embodiments the second flange may be approximately perpendicular
to the longitudinal axis of the conical side wall and may form a bottom
portion
of the capsule body. This allows the use of a flat welding iron having a
welding
area corresponding approximately to the area of the circumferential second
flange.
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In some embodiments the second flange may have a width in radial direction
of 2 to 3 mm, preferably between 2.2 and 2.5 mm, such that the inlet sealing
membrane may be permanently attached in a tight sealing manner.
In some embodiments the diameter of inlet sealing membrane may be 5 to 15
%, preferably about 10%, larger than the outer diameter of the second flange,
such that it partially covers the centring ramp when attached to the second
flange. The outer diameter of the second flange also corresponds to the inner
diameter of the centring ramp.
In some embodiments the second flange and the inlet sealing membrane may
form a flat bottom portion of the capsule.
In some embodiments the capsule body may be thermoformed from a layered
plastic sheet material comprising on both outer sides a layer of polypropylene
and an inner barrier layer of EVOH.
In some embodiments the membrane may be a metallic membrane preferably
of aluminium. The inlet membrane may be coated on the sealing side with
polypropylene to improve welding onto the first or second flange,
respectively.
In some embodiments the inlet membrane may be permanently attached to
the second flange by thermo welding.
In some embodiments the inlet and/or outlet sealing membrane may be
structured by embossing.
Brief Explanation of the Figures
The invention is described in greater detail below with reference to
embodiments that are illustrated in the figures. The figures show:
Fig. 1 a perspective view of the capsule showing the inlet side;
Fig. 2 a sectional view of the capsule of Fig. 1;
Fig. 3 a detailed view of the capsule of Fig. 1; and
Fig. 4 a detailed view of the capsule during welding.
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Embodiments of the Invention
Fig. 1 and Fig. 2 show a perspective view and a sectional view of the capsule
according to the invention. The capsule 1, which may be filled with roasted
and ground coffee (not shown), has a truncated cone-shaped capsule body 2
made of thermoformed plastic. The capsule body 2 has a conical side wall 3
the wider end of which defines an outlet side 4 of the capsule 1 and the
narrower side of which defines an inlet side 5 of the capsule 1. The inlet
side 5
of the capsule 1 refers to the water entering side of the capsule in use,
where
hot injection means of a expresso machine penetrate into the capsule. The
outlet side 4 of the capsule 1 refers to the side, where the brewed coffee
leaves the capsule 1.
The capsule body 2 comprises on its wider end an outwardly directed (away
from the longitudinal axis A of the capsule body) circumferential first flange
6
provided with a sealing and clamping area 7 to seal the capsule 1 against a
brewing chamber of a expresso machine and hold the capsule in said brewing
chamber in position while the coffee is brewed. A destructible outlet sealing
membrane or film 8 of aluminium is welded from the outside onto the first
flange 6.
The capsule body 2 is further provided with an inwardly directed (towards the
longitudinal axis A of the capsule body) circumferential second flange 9 on
the
narrower inlet side defining an inlet opening 10. The second flange 9 is
formed
after the thermoforming process by cutting the opening 10 into the bottom of
a preformed capsule body. A destructible inlet sealing membrane or film 10 of
aluminium is welded from the inside onto the second flange 9 to sealingly
close the inlet opening 10. The diameter of the inlet opening 10 is designed
such that hot injection needles or piercing members of the expresso machine
cannot touch the plastic capsule body 2 while penetrating into the capsule 1,
but only pierce the aluminium sealing membrane 10.
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The second flange 9 is approximately perpendicular to the longitudinal axis A
of the conical side wall 3 forming a bottom portion of the capsule body 2. The
width in radial direction of the second flange is 2 to 3 mm, preferably
between
2.2 and 2.5 mm, most preferably approximately 2.4 mm, to allow enough
contact area for welding the inlet sealing membrane 11 onto the capsule body
2.
Between the second flange 9 and the conical side wall 3, the capsule body 2
further comprises a circumferential centring ramp 12 with an off-axis angle to
the longitudinal axis A of 20 to 50 degrees, prefereably about 35 to 40
degrees, as can be nicely seen in the detailed views of Fig. 3 and Fig. 4.
The centring ramp 12 fulfils two functions: firstly it supports the precise
alignment of the inlet sealing membrane 11 with the second flange 9 and the
inlet opening 10 when placed inside the capsule body 2 during the
manufacturing process of the capsule 1; secondly it supports protection of the
conical side wall 3 from the heat of the sealing tool e.g. in form of a
welding
iron 14 (see Fig. 4) during the thermo welding. Therefore, the circular inlet
sealing membrane 10 has a diameter slightly larger as the outer diameter of
the second flange 9 (or the corresponding inner diameter of the centring ramp
12), preferably larger by about 5 to 15 %, more preferably by about 10%. The
oversize together with the inclined centring ramp 13 leads to an upwards bend
14 of the circular edge of the inlet sealing membrane to form a heat
protecting
layer between a hot sealing tool 14 and the plastic capsule body 2 during
welding (see Fig. 4).
Both the outlet and inlet sealing membrane (8, 11) are provided with a
coating, preferably polypropylene, in order to effectively weld it onto the
respective flange (6, 9). The sealing membranes (8, 11) of aluminium may
further have an embossed structure to reduce unintentional tearing of the
membrane.
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Reference Signs
1 capsule
2 capsule body
3 conical side wall
4 outlet side
5 inlet side
6 first flange
7 sealing area
8 outlet sealing membrane
9 second flange
10 inlet opening
11 inlet sealing membrane
12 centring ramp
13 bend in inlet sealing membrane
14 sealing tool / welding iron
