Note: Descriptions are shown in the official language in which they were submitted.
CA 02571698 2006-12-15
Brewing apparatus for a coffee machine
Technical field:
The present invention relates to a brewing apparatus
for a coffee machine, in particular for domestic use,
having a housing which encloses a brewing chamber and
has a nozzle assembly arranged on one side and a base
with an outflow for the brewed fluid arranged on the
opposite side, a flexible sealing element being
provided between the nozzle assembly and housing and
having the brewing chamber arranged on one side and a
fluid-fillable chamber arranged on its opposite side,
and it being possible for the sealing element to be
moved in the direction of the brewing chamber via an
increase in pressure in the chamber.
Background art:
EP 1625813 Al discloses a brewing apparatus for a
coffee machine in which a brewing chamber is bounded on
one side by a flexible sealing element which can be
moved in relation to the brewing chamber during the
brewing operation, an extraction substance which is
located in the brewing chamber thus always being
enclosed to good effect on all sides. This improves the
quality of the brewing operation, the sealing element,
once subjected to pressure, being moved back into a
starting position again. If, however, the pressure is
not fully dissipated, the sealing element may remain
deformed, which can have an adverse effect on
functionality.
Summary of the invention:
The object of the present invention is thus to provide
a brewing apparatus for a coffee machine which ensures
reliable sealing of the brewing chamber and, in
addition, is not susceptible to wear.
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This object is achieved by a brewing apparatus having
the features of claim 1.
According to the invention, the chamber which is
adjacent to the flexible sealing element is connected
to a venting valve in order to relieve the sealing
element of loading, so that, following the brewing
operation, the pressure in the chamber is reduced to
ambient pressure and the sealing element can move back
freely into the starting position. The venting valve
here may be of comparatively small design since it is
usually only small quantities of fluid, mostly air or
water, which have to be discharged. This ensures,
however, the same pressure on both sides of the sealing
element, this then avoiding permanent deformation of
the sealing element when not in use.
According to a further configuration of the invention,
the chamber is connected to a supply line to the nozzle
assembly via a pressure relief valve. The supply line
to the nozzle assembly is usually designed as a heating
line, so that a pressure can form in the supply line in
a reheating phase. It is intended here, however, to
prevent renewed opening of the nozzle assembly and the
associated dripping into the coffee cup. It is thus
possible to evacuate a corresponding pressure in the
reheating phase via the pressure relief valve, the
chamber then ensuring pressure equalization via the
venting valve. In addition, the pressure relief valve
may also act as a backflow check valve which, in the
pressureless state, prevents the supply line from
emptying into the nozzle assembly. This allows
particularly good metering of the fluid fed.
According to a still further configuration of the
invention, the chamber can be subjected to pressure via
a pump which also feeds the fluid to the nozzle
assembly. Consequently, just one pump is required for
feeding the water to the nozzle assembly and for
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subjecting the chamber to pressure. The lines can be
branched downstream of the pump and upstream of a
heating element.
The nozzle assembly is, according to a still further
configuration of the invention, closed via a nozzle-
assembly valve which is opened via the sealing element
when the pressure in the chamber increases. The
quantity of fluid fed by way of the nozzle-assembly
valve can thus be metered to particularly good effect.
For compact configuration of the brewing apparatus, the
venting valve and pressure relief valve may be coupled
to one another via a common tappet. This reduces the
number of components required, the tappet being
prestressed into a position in which the pressure
relief valve is closed and the venting valve is open.
It is only when the pressure in the chamber increases
in order to feed a fluid that the venting valve is
closed and the pressure relief valve is opened.
Brief description of the drawings:
The invention is explained in more detail hereinbelow
by way of an exemplary embodiment and with reference to
the accompanying drawings, in which:
figure 1 shows a sectional side view of a coffee
machine with a brewing apparatus according to
the invention, and
figure 2 shows a detail-specific view of the brewing
apparatus of the coffee machine of figure 1.
Description of the preferred embodiments:
A coffee machine 1 comprises a storage container 2 for
clean water, the storage container having provided on
it an outlet valve 3 which is connected to a pump 5 via
a line 4. By means of the pump 5, the water can be led
to a heating plate 6 which contains helical through-
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passages 7 in which the water can be heated. Provided
alongside this is a plate 8 which forms part of a
nozzle assembly and in which is provided a supply line
30 for the heated water. Installed on the plate 8 is a
mount 9 for a sealing element 20 which is of
essentially annular design and has a nozzle 11 provided
in its center. Via the nozzle 11, the heated water can
flow into a brewing chamber 19 which is enclosed by a
housing 10. Provided on the opposite side of the nozzle
11 is a base 12 which is intended for bounding the
brewing chamber 19 and which contains an outflow, so
that the fluid brewed flows through a funnel-like
outlet 13 to an extension arm 14, on which an outlet
opening 15 is provided for the purpose of filling
coffee cups.
The coffee machine 1 comprises a brewing chamber 19 in
which it is possible to insert one or more portion
packs with coffee. Provided for this purpose is a
covering 16 on which is formed a handle 17, via which
the housing 10 can be released from the nozzle assembly
and pivoted via an actuating mechanism, so that the
brewing chamber 19 is filled from above. The covering
16 is then closed and the housing 10 is moved into the
position shown. Following the brewing operation, the
portion packs are then emptied into a collecting
container 18 in order for the brewing chamber 19 to be
filled anew. For the subject matter of the present
application, however, it is possible to use quite
different actuating mechanisms for the purpose of
filling the brewing apparatus with one or more portion
packs.
Figure 2 illustrates part of the brewing apparatus of
the coffee machine 1 in detail.
The annular sealing element 20 is fitted on the mount
9, in which case, on the sealing element 20, an outer
sealing lip butts against a crosspiece 22 of the mount
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9 and an inner sealing lip 23 butts against a cross-
piece 24 of the mount 9. An annular chamber 31 is thus
formed between the mount 9 and sealing element 20 and
ensures that the sealing element 20 is moved in the
direction of the brewing chamber 19 when the chamber 31
is subjected to pressure. Coupled to the sealing
element 20 here is a plate-like pressure-exerting
element 26 which can be pressed against the wall of a
portion pack containing ground coffee. The sealing
element 20 and the plate-like pressure-exerting element
26 here can be moved up to a stop which is formed by a
projecting flange 27 on the nozzle.
The chamber 31 here is connected directly to a valve
chamber 33 which can be supplied with water via a
supply line 50, the water being fed by the pump 5. The
supply line 50 may be connected here upstream of the
heating plate 6, downstream of the pump 5.
Two valves are provided on the valve chamber 33. A
venting valve 32 connects the valve chamber 33 to a
venting line 37. The venting valve 32 here is formed by
a diaphragm 34 containing one or more openings 38. The
diaphragm 34 here is secured, on one side, on an insert
51 and the mount 9 and, on the inside, on a movable
tappet 35. The tappet 35 is prestressed toward the left
in figure 2 via a spring 36, so that the opening 38 is
not closed by a wall of a valve housing 39.
If the pressure in the valve chamber 33 is increased by
the pump 5, the diaphragm 34 is subjected to pressure
and moves the prestressed tappet 35 to the right, so
that the venting valve 32 is closed.
Provided on the opposite side of the tappet 35 is a
pressure relief valve 44, which is connected to the
helical through-passages 7 of the heating plate 6. The
pressure relief valve 44 comprises a second diaphragm
41, which is secured on the outside between the mount
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51 and the plate 8. The diaphragm 41 here is supported
on the plate 8 via a supporting disk 43, the diaphragm
41 and supporting disk 43 being provided with a
through-opening 42 which is connected to the through-
passages 7. The through-opening 42 is closed by an end
side 40 of the tappet 35.
Furthermore, the insert 51, sealed via a plurality of
sealing elements 52 is accommodated between the plate 8
and the mount 9.
The operation of the brewing apparatus is described in
detail hereinbelow, figure 2 showing the pressureless
state in which the pump 5 has been switched off and the
venting valve 32 is open.
If the pump 5 is switched on, the water flows, via the
water inlet 50, into the valve chamber 33 and the
chamber 31. The sealing element 20 thus moves in
relation to the brewing chamber 19, seals the latter
and, at the same time, opens a nozzle-assembly valve,
so that heated water can flow through the brewing
chamber 19 by way of the nozzle 11. The built-up
pressure in the through-passages 7 is thus evacuated
into the brewing chamber 19.
In a first phase, the end edge 40 of the tappet 35
butts against the through-opening 42, so that the
through-passages 7 are separated off from the valve
chamber 33. At the same time, the valve chamber 33 is
vented via the opening 38 of the venting valve 32. This
allows trapped air and possibly water to be discharged
to the venting line 37.
If the pressure in the valve chamber 33 then increases,
the tappet 35 moves to the right, on account of the
diaphragm 34, and closes the venting valve 32. This
simultaneously releases the through-opening 42 in
relation to the through-passages 7. The brewing
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apparatus is then located in the operating position and
the heated water can flow into the brewing chamber 19
by way of the nozzle 11. In this state, there is equal
static pressure in the brewing chamber 11, the through-
passages 7, the valve chamber 33 and the chamber 31.
If the pump 5 is switched off, the pressure dissipates,
in the first instance, via the nozzle 11 and the
nozzle-assembly valve, until the spring 36 forces the
tappet 35 onto the opening 42 again and the venting
valve 32 is thus opened and the opening 38 no longer
butts against the housing cover 39. The sealing element
is thus relieved of loading and can move back into
the starting position, as a result of which the nozzle-
15 assembly valve is also closed.
The valve chamber 32 is vented via the opening 38 in
the diaphragm 34. Venting here, on the one hand, causes
the sealing element 20 to be fully relieved of loading
20 and, on the other hand, ensures that the nozzle-
assembly valve can close again without force being
applied. Furthermore, the pump 5 need not take in
counterpressure if there is a lack of water in the tank
2, which accelerates this operation to a considerable
extent.
The pressure relief valve 42 also performs the function
of a backflow check valve, so that it is not possible
to empty the water in the through-passages 7 of the
heating plate 6. This is because the pressure relief
valve 44 and the nozzle-assembly valve ensure that the
water contained in the through-passages 7 remains there
and the through-passages 7 cannot empty during the
reheating phase. Particularly precise metering of the
quantity of liquid is possible as a result.
Furthermore, the pressure relief valve 44 has a
function to perform in the reheating phase, when the
pressure in the through-passages 7 of the heating plate
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6 increases as a result of heating. The force of the
spring 36 may be such that the pressure in the
reheating phase is limited and, if required, the tappet
35 is moved to the right by the positive pressure
occurring and the fluid can be discharged into the
valve chamber 33 in order to equalize pressure in the
through-passages. It is conceivable here to set the
pressure difference for initiating the pressure relief
valve by a corresponding configuration of the spring
36.
In the exemplary embodiment illustrated, the venting
valve 32 and pressure relief valve 44 are coupled to
one another via a common tappet 35. It is, of course,
also possible to provide the venting valve 32 and
pressure relief valve 44 separately from one another.
Other valves may also be used.
