Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~039026
Automatic appliance for instant coffee and process
for the operation of this
The present invention relates to an automatic
appliance for instant coffee, comprising a pressure
chamber for preparing the coffee, this pressure chamber
having a closing~opening element for introducing and
eliminating the coffee powder and at least one adjustable
moveable wall defining the volume of the chamber, a water
supply conduit and a coffee outlet conduit, and control
means determining a po~ition of the moveable wall and the
quantity of water and coffee. It also relates to a
process for the operation of such an appliance.
~here are known coffee machines, in which a
cylinder/piston assembly compresses ground coffee in a
cylindrical pressure chamber, the pressure being exerted
by the head of the piston, itself actuated by a motor,
cam or other method. Such machines are described, for
example, in European Patent Application EP-A-0,073,739.
The disadvantage of these machines is that the
pressure chamber thus defined presents only a fixed
volume at the moment of in~ection of hot water or steam.
In this fixed volume, the water or steam does not circu-
late perfectly through the mass of ground coffee and
cannot draw all the aroma from it.
The ob~ect of the invention is to overcome this
disadvantage by providing, in such an automatic
appliance, a pressure chamber, one characteristic of
which is that it is expandable at the moment of in~ection
of hot water or steam.
The advantage affarded is a bettqr impregnation
of the coffee powder by the hot water or steam and
therefore a coffee of higher quality.
In an advantageous embodiment of the invention,
the pressure chamber comprises a cylinder/piston
assembly, the moveable wall consisting of the head of the
piston and the expansion of the chamber being obtained as
a result of the retraction of the head of the piston.
Preferably, this pi~ton has a widened base sliding on at
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least one guide column parallel to the axis of the
cylinder, the widened base is coupled by elastic con-
nection means to a thrust piece sliding on the same guide
column or guide column~ as the widened base, stop means
lLmit the spacing between the thrust piece and the
widened base, and the position of the thrust piece is
determined by a rotationally moveable screw/rotationally
stationary nut system, the nut being integral with the
thrust piece and the screw being parallel to the axis of
the cylinder.
In another embodiment, the elastic connection
means consist of one or more springs and the widened base
and the thrust piece are rectangular plates of the same
dimensions and have at least one blind hole designed for
receiving the spring or springs. The closing/opening
element can comprise a flange pivoting about an axis
parallel to the axis of the cylinder, and the outlet
conduit for the liquid coffee is arranged in the pivoting
flange.
In another embodiment, the hot-water or steam
supply conduit opens into the moveable wall of the
pressure chamber; arranged in the piston and its widened
base is a blind hole intended to allow the screw to pass
through when the piston is in the position of maximum
retraction; the means for driving the closing/opening
element and for driving the screw comprise motors grouped
side by side.
In this last advantageous embodiment of the
invention, the overall size of the machine is reduced as
a result of the three characteristics, more specifically:
- the location of the hot-water or steam supply in the
piston head coming under pressure up against the ground
coffee makes it po~ible to limit the height of the
appliance;
- the blind hole made in the piston and its widened base
for partially inserting there the screw of the screw/nut
system makes it possible to save the height occupied by
some of the space taken up by the screw/nut system;
- by grouping the means for driving the screw on the one
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hand and for driving the closing/opening element rep-
resented by a pivoting flange on the other hand side by
side at the bottom of the appliance, greater access to
the other parts of the appliance is obtained.
S The invention also relates to an operating
process for such an automatic appliance, in which coffee
powder is introduced into the pre~sure chamber, after
which the chamber is closed and the coffee powder is
compressed by the moveable wall of the pressure chamber
before the in~ection of hot water or steam and the flow-
off of liquid coffee, defined in that the control means
determine the position of the thrust piece, the position
of the moveable wall of the pressure chamber being
determined both by the position of the thrust piece and
by the pressure prevailing in the pressure chamber,
allowing an expansion of the volume of the pressure
chamber at the moment of in~ection of hot water or steam.
A preferred embodiment of the appliance and its
- operation are described below with reference to the
accompanying drawings in which:
- Figure 1 shows the appliance ready for operation,
- Figure 2 shows the step of the compression of the
coffee, before the in~ection of hot water;
- Figure 3 show~ a step of e~ecting the used coffee cake;
- Figure 4 shows, in a side view of the appliance, the
position of the hot water or steam supply and coffee
outlet conduits.
In Figure 1, the appliance is ready for
operation. The pivoting flange 20 is in the open
position, exposing the entrance of the pressure chamber
10 to allow the intake of ground coffee; the piston 30 is
in the position of maximum retraction, maximizing the
volume of the pressure chamber 10.
When the user orders one or t~o CUp8 of coffee
from the control panel (not shown), the control means
(not shown) release an appropriate quantity of ground
coffee, poured into the pressure chamber 10, via a nozzle
(not shown) openinq out above the pressure chamber 10.
The flange 20 pivots into the closed position, shutting
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off the pressure chamber 10, a~ shown in Figure 2.
Control means known per se determine the total
stroke of a thrust piece represented by a plate 42
sliding on stationary columns 43O The displacement of
this plate 42 depends, by way of a screw~nut system, on
the angle of rotation of a screw 40 actuated by driving
means 38 coupled to an electric motor (not shown~. This
angle is adjusted as a function of various parameters,
particularly the selected number of cups, the grinding
and nature of the coffee and the desired flow-off speed;
the nut 41 integral with the plate 42 converts this angle
of rotation into a displacement parallel to the axis 34
of a cylinder and to the columns 43. A blind hole 36
arranged in the piston 30 i~ provided, into which the
screw 40 is partially inserted. The position of the
widened base of the piston 30, represented by a plate 32,
is determined by that of th0 plate 42 and by the com-
pression of the springs 50 arranged in blind holes 53
made in the plates 32 and 42. The relative spacing of the
plates 42 and 32 is limited by the stop means consisting
of shoulders 52 of stop screws 51. The position of the
moveable wall 31 of the pressure chamber, represented by
the head of the piston 30 fixed to the plate 32, is
determined so as to exert a specific pressure on the
coffee which is thus compacted into a cake 33. During the
injection of hot water or steam under pressure via the
conduit 23 and the flow-off of the coffee via the outlet
conduit 22, both of which can be seen in Figure 4, the
wall 31 is capable of retracting together with the plate
32, compressing the springs 50 a little more and thus
ensuring the desired expansion of the pressure container
containing the coffee cake 33.
After the cups have been filled and the in~ection
of hot water or steam has ceased, the control means cause
the plate 42 and indirectly the wall 31 of the pressure
chamber to retract slightly, in order to reduce the
pressure exerted on the working face 21 of the flange 20
by way of the coffee cake 33; the flange 20 pivots into
the open position, and according to Figure 3 the wall 31
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of the pressure chamber advances as far as the position
previously occupied by the working face 21 of the flange,
thus expelling the cake 33 of spent ground coffee, the
flange 20 pivots into the closed position, at the same
time scraping the wall 31 of the pressure chamber, thus
removing the cake 33 of spent ground coffee, and then
returns to the open position, and the wall 31 of the
pressure chamber retracts to its maximum extent, the
machine thus being ready once again for operation, as in
Figure 1.
By grouping the means 37, 38, actuated by
electric motors (not shown), for driving the screw 40 on
the one hand and the pivoting flange 20 on the other hand
side by side at the bottom of the appliance, greater
acces~ to the other parts of the appliance is obtained.
It goes without saying that the invention is not
limited by the exemplary embodiments described.
