U.S. patent application number 12/516709 was filed with the patent office on 2010-02-11 for beverage dispensing machine and operating method.
This patent application is currently assigned to RHEA VENDORS S.P.A.. Invention is credited to Luca Doglioni Majer.
Application Number | 20100031826 12/516709 |
Document ID | / |
Family ID | 37969826 |
Filed Date | 2010-02-11 |
United States Patent
Application |
20100031826 |
Kind Code |
A1 |
Doglioni Majer; Luca |
February 11, 2010 |
BEVERAGE DISPENSING MACHINE AND OPERATING METHOD
Abstract
The present invention relates to a beverage dispensing machine,
for instance a coffee machine, provided with a brewing chamber and
at least one valve for totally and/or partially blocking the
beverage from exiting the chamber. Advantageously, the valve is an
electrovalve, in particular a piezoelectric valve, which is
continuously controllable to adjust the beverage flow rate being
permitted to exit the chamber.
Inventors: |
Doglioni Majer; Luca;
(Carate Urio (Como), IT) |
Correspondence
Address: |
HESS PATENT LAW FIRM, P.C.
9 MIRAMAR LANE
STAMFORD
CT
06902
US
|
Assignee: |
RHEA VENDORS S.P.A.
Caronna Pertusella (VA)
IT
|
Family ID: |
37969826 |
Appl. No.: |
12/516709 |
Filed: |
December 5, 2007 |
PCT Filed: |
December 5, 2007 |
PCT NO: |
PCT/IB07/03770 |
371 Date: |
June 29, 2009 |
Current U.S.
Class: |
99/279 ; 700/283;
99/323.3 |
Current CPC
Class: |
A47J 31/5251 20180801;
A47J 31/465 20130101; A47J 31/56 20130101; A47J 31/5255 20180801;
A47J 31/5253 20180801; A47J 31/461 20180801 |
Class at
Publication: |
99/279 ;
99/323.3; 700/283 |
International
Class: |
A47J 31/44 20060101
A47J031/44; A47J 31/00 20060101 A47J031/00; G05D 7/00 20060101
G05D007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 6, 2006 |
EP |
06025196.4 |
Claims
1: A beverage dispensing machine provided with a brewing chamber
(2) and at least one valve for totally and/or partially blocking
said beverage, characterized by said at least one valve being an
electrovalve (3, 3') controllable to adjust the beverage flow rate
which exits the brewing chamber (2).
2: The beverage dispensing machine according to claim 1, wherein
said electrovalve (3, 3') is a piezoelectric valve.
3: The beverage dispensing machine according to claim 1, wherein
said electrovalve is provided at least at the discharge outlet (39,
39') of said brewing chamber (2).
4: The beverage dispensing machine according to claim 1, further
comprising an electronic control unit (5) and said electrovalve (3,
3') is electrically controlled by said control unit to obstruct the
said outlet (39, 39'), totally, or partially to the desired
extent.
5: The beverage dispensing machine according to claim 4, wherein
said control unit (5) operates said electrovalve (3, 3'), on the
basis of memorized algorithms, to adjust the pressure within the
brewing chamber (2).
6: The beverage dispensing machine according to claim 5, wherein it
further comprises means to monitor one or more operative parameters
of the machine, and said control unit (5) operates said
piezoelectric valve (3, 3') to compensate for variations of one or
more of said parameters from an expected value.
7: A method for operating a beverage dispensing machine provided
with a brewing chamber, characterized by regulating the
opening/closing of the chamber (2) discharge outlet, to the desired
extent, by means of an electrically operable valve (3, 3').
8: The method of claim 7, wherein said electrovalve (3) is a
piezoelectric valve.
9: The method of claim 7, wherein said electrovalve (3) is operated
to open said outlet (39, 39') only after a preset time lapse that
water is supplied to the brewing chamber (2).
10: The method of claim 7, wherein said electrovalve is operated to
open said outlet (39, 39') only after a preset pressure is reached
within the brewing chamber (2).
11: The method of claim 7, wherein said electrovalve (3, 3') is
operated to adjust the beverage flow rate of the beverage being
dispensed.
12: The method of claim 7, wherein an electronic unit (5) provides
a feedback control over said electrovalve (3, 3'), adjusting
pressure within the brewing chamber (2) to compensate for undesired
variations of the brewing conditions.
13: The method of claim 7, wherein an electronic unit (5) controls
said electrovalve (3, 3') to adapt the pressure within the brewing
chamber (2) and/or the said flow rate correspondingly to the
beverage type chosen by the user and prepared by the machine.
14: The method according to claim 7, wherein said electrovalve (3)
is operated during a stand-by condition of the machine to promote
self-cleaning of the same valve (3, 3') and the related seat (39,
39').
Description
FIELD OF THE INVENTION
[0001] The present invention concerns a beverage dispensing machine
and a method for its operation, in particular a fully-automatic or
semi-automatic coffee/beverage dispensing machine.
[0002] Automatic or semi-automatic machines are known for preparing
coffee drinks, or the like, by providing a forced flow of hot water
to pass through a brewing chamber containing coffee powder, wherein
sometime a mechanic valve is positioned at the exit of the chamber
to adjust the backpressure. The valve is calibrated to set both the
pressure of the water within the chamber and the time lapse of
infusion of the coffee powder.
[0003] In general, with beverage dispensing machine it is meant a
semi-automatic (the user has to intervene in the preparation of the
beverage) or fully automatic machine (preparation of the beverage
is carried out automatically by the machine with no need for the
user to intervene but for the selection of the desired beverage)
for preparing and dispensing a beverage such as, espresso coffee,
Americano coffee, cappuccino, latte macchiato, tea, or the
like.
DESCRIPTION OF THE PRIOR ART
[0004] US 2001/0050002 discloses a machine for preparing an
espresso coffee. The brewing chamber comprises a threaded seat,
coaxial with the chamber outlet nozzle, wherein a threaded member
is inserted which operates as a manually adjustable valve. The
threaded member can be screwed within the seat to obstruct the
outlet nozzle to a greater or lesser extent, i.e. to partially
close the brewing chamber outlet. By adjusting the extent of the
insertion of the threaded member within the related seat, the
backpressure within the brewing chamber can be adapted to obtain an
espresso coffee having the desired organoleptic characteristics.
The extent of the insertion of the threaded member within the
related seat is provided when the machine is assembled.
[0005] U.S. Pat. No. 6,711,988 discloses an espresso machine
provided with a piston moveable within the brewing chamber to press
the coffee powder contained therein and to adjust the volume of the
same chamber. At the chamber outlet, in correspondence of the
coffee discharge outlet, a mechanical valve is provided to adjust
the backpressure. The valve comprises a spring which supports a
ball. Normally the ball is pressed by the spring against the
discharge outlet of the brewing chamber, thereby preventing the
beverage from exiting the chamber. Only when the pressure of the
coffee beverage within the chamber is sufficient to contrast the
spring load, then the ball is forced back and the beverage is
delivered outside the chamber. Controlling of the operation of the
valve is achieved by choosing the compression spring characteristic
of the valve spring to be installed.
[0006] As a matter of fact, traditional machines do not allow for
controlling the operation of the valve which acts as a shutter at
the brewing chamber outlet. In other words, known valves mostly
operate as on/off valves and cannot be controlled to rapidly, or
instantly, adjust the backpressure to the desired extent, for
instance in order to compensate for other non optimal operating
parameters of the coffee machine.
[0007] Also, known valves cannot be set to a backpressure value
different from the one corresponding to the initial design value
without dismantling the machine or manually adjusting the means for
creating the backpressure. This drawback applies not only to
espresso coffee machines, but also to other manual or automatic
machines for preparing and dispensing espresso and other beverages,
such as different kinds of coffee drinks (espresso, Americano,
cappuccino, etc.), tea, chocolate, etc., which are usually provided
with such known valves.
[0008] Therefore, the need is felt for machines which allow a
control of the operation of the brewing chamber outlet valve to
modify brewing time and pressure, and also the brewing process, for
meeting the user's taste for what concerns the organoleptic
characteristics of the prepared beverage.
[0009] Another drawback of known beverage dispensing machines is
that they require periodical maintenance for cleaning the valve
provided at the brewing chamber outlet. Residues of the dispensed
beverages, which build up in correspondence of the valve seat, very
often jeopardize the proper functioning of traditional valves. In
particular the valve body adheres to the related seat due to the
adhesive effect of the residues, thereby retarding or preventing
opening of the valve.
SUMMARY OF THE INVENTION
[0010] It is an object of the present invention to provide a
beverage dispensing machine which obviates the aforesaid drawbacks,
being at the same time not expensive, simple to operate and easy to
keep clean.
[0011] It is still another object of the present invention to
provide a beverage dispensing machine which allows for rapidly
controlling of the beverage flow rate exiting the brewing
chamber.
[0012] It is a further object of the present invention to provide a
beverage dispensing machine which allows for instantly controlling
the valve provided at the exit of tie brewing chamber, during the
phases of preparing and dispensing the beverage, in order to
compensate for possible alterations of other parameters of the
machine from the optimal value.
[0013] It is a further object of the present invention to provide a
beverage dispensing machine provided with a valve within the outlet
of the brewing chamber, which valve can be controlled during the
phases of preparing and dispensing the beverage in order to affect
the brewing conditions, so as to meet the user's preferences with
respect to the type and quality of the selected beverage.
[0014] These and other objects are achieved by the present
invention which relates to a coffee/beverage dispensing machine
according to claim 1. The machine may be fully-automatic or
semi-automatic.
[0015] The invention dispensing machine provides several advantages
over prior art embodiments.
[0016] Electrovalves are easy to control continuously, e.g. the
control unit can operate the electrovalves at each time during the
beverage preparation process. Among the electrovalves,
piezoelectric valves have a quick response to electric inputs. The
control unit of the machine commands the valve by electric signals
to rapidly achieve the desired control over the flow rate of the
beverage exiting the brewing chamber. The control unit operates on
the basis of memorized algorithms.
[0017] Advantageously, the electrovalve not only provides an on/off
functioning, but does provide also for adjustable choking of the
brewing chamber exit.
[0018] Preferably the electrovalve is a piezoelectric valve
positioned at the exit of the brewing chamber, for instance within
the outlet conduit of the same. Alternatively, the piezoelectric
valve may be positioned upstream the brewing chamber.
[0019] The machine according to the present invention allows for
the electrovalve to be electrically controlled to open/close the
outlet of the brewing chamber, to the desired extent, during the
operation of the machine. The control unit can operate the valve to
compensate at least some undesired changes of the machine operative
parameters which are preset for a given beverage to be prepared
such as, for instance, the temperature of the water supplied to the
brewing chamber, the brewing time, the size of coffee powder, the
volume of the brewing chamber, etc.
[0020] The control can be a "real time" adjusting of the valve at
the exit of the brewing chamber, i.e. while the beverage is being
dispensed; the control can also be carried out before each
preparation of the beverage, i.e. for adapting brewing pressure and
time to the type of beverage selected by the customer.
[0021] For instance, if the beverage to be dispensed is an espresso
coffee, the control unit commands the valve to open the exit of the
brewing chamber after a first time lapse and with a selected flow
rate. If the beverage to be dispensed after the espresso is an
"Americano" coffee, the control unit commands the valve to open the
exit of the brewing chamber after a second time lapse, shorter than
the first time lapse, and with a higher flow rate.
[0022] A further advantage is that the valve according to the
invention is simple to clean, especially the piezoelectric valve.
The piezoelectric valve can be operated during a stand-by of the
dispensing machine, i.e. when no beverage is being prepared, to
promote cleaning of the valve shutter member and the related seat.
The valve shutter can be rapidly moved within its seat to clean the
related surfaces from residues left by the dispensed beverages. In
this way maintenance of the valve is simple and effective, with no
need for an external operator to intervene often.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Further advantages and features of the present invention
will become apparent from the following detailed description, with
reference to the drawings enclosed as a non-restrictive example,
where:
[0024] FIG. 1 is a scheme of a beverage dispensing machine
according to the present invention;
[0025] FIG. 2 is a schematic section view of a first piezoelectric
valve to be used in the machine according to the present
invention;
[0026] FIG. 3 is a section view of a particular of the valve shown
in FIG. 2, in a first configuration;
[0027] FIG. 4 is a section view of a particular of the valve shown
in FIG. 2, in a second configuration;
[0028] FIG. 5 is a section view of a second piezoelectric valve to
be used in the machine according to the present invention;
[0029] FIG. 6 is a schematic section view of a third valve to be
used in the machine according to the present invention;
[0030] FIG. 7 is a schematic section view of a fourth valve to be
used in the machine according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0031] With reference to FIG. 1, it is shown a simplified scheme of
a beverage dispensing machine according to the present invention,
provided with a water heater 1, a brewing chamber 2, an
electrovalve 3 positioned downstream of the chamber 2 and a
discharge section 4 for delivering the beverage to the user.
Preferably the electrovalve 3 is a piezoelectric valve, i.e. a
valve which can be activated by virtue of the response of a
piezoelectric element to electric signals provided by a control
unit. Alternatively the electrovalve 3 is a proportional
electrovalve. A suitable proportional electrovalve is the series
servo-valve sold by the company MOOG Inc.
[0032] A control unit 5, for instance an electronic unit, controls
at least the valve 3. Preferably the control unit 5 controls the
operation of also the water heater 1 and the brewing chamber 2.
Control unit 5 runs on the basis of memorized algorithms, which may
be software programs, firmware, etc.
[0033] The water heater 2 supplies heat to the water which, in
turn, is channelled toward the brewing chamber 3 where the beverage
is prepared. The water heater may be provided with a temperature
sensor which communicates the temperature of the water to the
control unit, thereby allowing the same to interrupt heating the
water when the desired temperature is achieved.
[0034] The brewing chamber 3 provides for a volume to be totally or
partially occupied by the ingredient used for preparing the
beverage, for instance coffee powder, tea, milk powder, etc.
Normally a piston is moveable within the brewing chamber to press
the powder to a given extent, i.e. the piston presses the powder at
a preset pressure. Preferably in the machine according to the
present invention the control unit controls operation of the piston
to adjust the pressure imparted to the powder.
[0035] The beverage is prepared by supplying hot water to the
powder contained within the brewing chamber. The quality of the
prepared beverage, i.e. its organoleptic characteristics, depend on
several operating parameters of the machine, such as the brewing
time, i.e. the time lapsed during infusion, the pressure of the
water supplied to the brewing. chamber, the amount of powder
contained therein and the related grain size, the water
temperature, etc.
[0036] It is evident that the operating parameters should also be
set depending on the type of beverage to be prepared and on the
user's preferences. For instance, the user may choose between at
least two types of coffee: espresso and americano coffee, and for
each beverage the machine should meet the user's preferences for
what concerns the quality or the organoleptic characteristics, for
instance by varying the amount of powder to be provided to the
brewing chamber, the water temperature, the grain size of the
coffee powder, etc.
[0037] The control unit 5 provides for setting of the operating
parameters of the machine on the basis of the user's choices. On
this purpose, the machine is provided with a user interface
allowing the user to select among several settings of the operating
parameters. According to the invention, the dispensing machine is
provided with at least one electrovalve 3, that is preferably
provided downstream of the brewing chamber for controlling the
beverage flow rate exiting the brewing chamber. As alternative, the
valve 3 is provided upstream of the brewing chamber for controlling
the water flow rate entering the brewing chamber. According to
another embodiment, two valves are provided, a first one 3A
upstream of the brewing chamber and the second one downstream of
the same chamber (FIG. 1).
[0038] Piezoelectric valves suitable for being used in the machine
of the invention are available on the market at low cost and are
proved to be reliable. In general such valves have minimum
dimensions, thereby being particularly suitable for installation at
the exit of the brewing chamber, where usually the room available
is limited.
[0039] Suitable valves are e.g. those sold by ASCO JOUCOMATIC,
series 630, and, more generally, those that can handle flow rates
within the range of 1-20 ml/s (when open) and pressures within the
range 1,5-20 bar.
[0040] Sensors S are provided for measuring the flow rate and/or
the pressure and/or the temperature of the flow downstream of the
water heater, upstream and downstream of the brewing chamber 2 and
downstream of the piezoelectric valve 3.
[0041] FIG. 2 shows a section view of a suitable piezoelectric
valve 3. The valve 3 comprises a body 31 arranged in fluid
connection with the brewing chamber 2 (shown in FIG. 1) directly or
through a short passage 32. A shutter 34 is moveable within the
body 31 to open/close a discharge outlet 39 which opens into a
beverage delivering section 4. The delivering section 4 is for
channelling the prepared beverage toward the user's cup, glass or
the like.
[0042] The shutter 34 may have several shapes. The one shown in
FIG. 2 is needle shaped and has a first end coupled to a
piezoelectric element 36 and a second distal end 38 which is
tapered or conical. The shape of the second distal end 38 is
complementary with respect the shape of a seat 39 of the valve body
31.
[0043] The shutter 34 slides across the internal wall 35 while
being biased by a spring element 37. Normally the shutter 34 abuts
the seat 39 with its distal end 38, i.e. normally the valve 3 is
closed.
[0044] Functioning of the valve 3 is simple. The control unit 5, by
means of the electric connection 33, activates the piezoelectric
element 36 which expands, at the same time overcoming the force of
the spring element 37, thereby causing the shutter 34 to retract
its second distal end 38 from the outlet/seat 39. When the outlet
39 is open, the beverage coming from the brewing chamber 2 and
entering the valve body 31 is allowed to flow toward the discharge
section 4. When the control unit 5 deactivate the piezoelectric
element 36, the shutter 34 is pushed by the spring element 37 back
in its initial position, thereby causing the second distal end 38
to abut the seat 39, thereby closing the exit and preventing the
beverage from flowing outside the valve body 31 toward the
delivering section 4.
[0045] Advantageously, the stroke of the shutter 34 is directly
controllable by the control unit 5 to adjust the flow rate of the
dispensed beverage. In particular, the stroke of the shutter 34
depends upon the voltage supplied by the control unit 5 to the
piezoelectric element 36.
[0046] FIGS. 3 and 4 show, in a section view, a particular of the
valve 3. The shutter 34 in FIG. 3 is raised above the seat 39 to a
minimum extent to allow a minimum flow rate of the beverage, for
instance 1 ml per second of espresso coffee. The shutter 34 in FIG.
4 is raised above the seat 39 to the maximum extent to allow the
maximum flow rate of the same beverage, for instance 10 ml per
second.
[0047] Advantageously the piezoelectric valve 3 allows the control
unit 5 for full controlling the beverage flow rate exiting the
brewing chamber, i.e. the control unit 5 operates the valve 3 so as
to adjust the flow rate from 0 ml/s (or approximately 0 ml/s) to a
maximum value of the flow rate, for instance 20 ml/s, preferably so
as to maintain the pressure within the chamber 2 substantially
constant.
[0048] It is to be understood that operation of the valve 3 has
effect also on the pressure of the water within the brewing chamber
2. When the valve 3 is closed, the pressure within the chamber 2
builds up while pressurized water is supplied from the water
heater, by means of a pump, to the same chamber 2. Depending on the
position of the shutter 34, a certain flow rate of beverage may
exit the brewing chamber 2, thereby reducing, or preventing, the
pressure build up. In this respect, the control unit 5 adjusts the
backpressure downstream from the brewing chamber by adjusting the
extent of the shutter 34 raising above the seat 39, i.e. by
diminishing or increasing the gap between the distal end 38 and the
seat 39.
[0049] For instance, the control unit 5 adjusts the position of the
shutter 34 to increase, reduce or stop the flow rate of the
beverage exiting the brewing chamber to, respectively diminish or
increasing the infusion time. The control unit 5 may also control
the operation of the valve 3 so as to maintain the pressure in the
brewing chamber within a preset range, for instance 10 to 15 bar,
or to compensate for possible variation in the grain size of the
coffee powder. In this respect, the control unit 5 provides for a
"real time" feedback control of the piezoelectric valve 3.
[0050] In order to clean the valve, the piezoelectric element of
the valve, for instance the element 36 in FIG. 2, is excited, i.e.
activated, by control unit 5 at high frequency to transmit
vibrations to the shutter 34. This is done when the beverage
dispensing machine is in stand-by, that is when the machine is not
required to prepare a beverage. When the shutter 34 is forced to
vibrate, during a cleaning cycle, residues which may be present on
the shutter 34 and the seat 39 surfaces are at least partially
detached. In other words, vibrations imparted to the shutter 34 and
the friction between the distal end 38 and the seat 39 promote
detaching of the residues from the surfaces.
[0051] The beverage dispensing machine according to the present
invention may provide for periodic cleaning cycles of the valve 3,
thereby preventing chocking of the seat 39 by the residues of the
dispensed beverages and subsequent malfunctioning of the
machine.
[0052] The valve of the invention machine may be provided with a
piezoelectric valve of a different type than valve 3. The shutters
and/or the seat are made of piezoelectric materials and the
opening/closing are obtained by the expansions of the elements upon
supplying a voltage to said shutter and/or to seat elements. This
embodiment has the additional advantage of being simple and faster
(no springs are required) and of improving the cleaning effect
because the valve is vibrated and expanded. The functioning of this
embodiment 3' is disclosed with reference to FIG. 5.
[0053] In FIG. 5 the shutter 38' is a disc fixed onto a support
shaft 34'. The wall 41' provides for the seat 39'. Either one of
the shutter 38' or the wall 41' is made of a piezoelectric material
and is electrically excited by control unit 5. Alternatively both
the shutter 38' and the wall 41' are made of a piezoelectric
material. When the valve 3' is operated, i.e. when control unit 5
excites the piezoelectric material of the shutter 38' and/or the
wall 41', such material undergoes an expansion, that is the
dimension change. For instance, when both the shutter 38' and the
wall 41' are made of a piezoelectric material, the shutter 38'
becomes wider while the seat 39' becomes narrower, thereby chocking
or definitely closing the outlet. The extent of the opening of the
valve 3' depends upon the entity of the expansion of the
piezoelectric material of the shutter and/or the related seat,
which expansion is adjusted by powering the material with the
proper voltage.
[0054] When only the shutter 38' is made of a piezoelectric
material, the seat 39' remains still, i.e. does not expand. When
only the seat 39', i.e. the wall 41', is made of a piezoelectric
material, the shutter 39' remains still, i.e. does not expand.
[0055] Cleaning of the valve 3' is accomplished as described above
with reference to valve 3, i.e. by vibrating the piezoelectric
member (either one of the shutter 38' and the wall 41', or
both).
[0056] Hereinafter there are disclosed two examples of the
operation of the machine according to the present invention, each
example being related to the preparation of a specific
beverage.
EXAMPLE 1
Coffee 1
[0057] An amount of 8 g of coffee powder is loaded in the brewing
chamber and pressed by a moveable piston at 10 kg/cm.sup.2. The
piston is blocked in its final position, i.e. above the coffee
powder, by means of mechanical or electrical restraining devices.
The coffee powder is provided by a grinder through a chute
extending toward the brewing chamber.
[0058] Water is heated by powering the water heater 1 until the
temperature sensor measures 90.degree. C. Circulation of the water
across the water heater 1 and toward the brewing chamber 2 is
provided by a pump (not shown) positioned upstream of the heater 1
(for instance a rotative pump).
[0059] An on/off valve, positioned upstream of the brewing chamber
2 is commanded by the control unit 5 to open, thereby allowing the
hot water to enter the chamber 2. At this time the piezoelectric
valve 3 remains closed and the pressure within the brewing chamber
increases.
[0060] After a preset time lapse, for instance 5 seconds, the
control unit 5 commands the valve 3 to open. The piezoelectric
valve 3 is promptly responsive and the shutter 34 is rapidly raised
a given extent above the seat 39, this causing the beverage to exit
the chamber 2. The pressure within the chamber suddenly drops, for
instance from 15 bar to 10 bar. If the user has selected a "strong"
espresso coffee, the control unit 5 commands the valve 3 to close
again for a short time lapse, for instance 20 ms, in order to
promote a pressure recover within the brewing chamber 2. Finally
the control unit 5 opens the valve 3 for completing delivering of
the beverage to the user.
[0061] After a preset time lapse from the beverage discharge, for
instance after 30 seconds (or later or once a day), if the machine
is not required to prepare a new beverage, the control unit 5
commands the valve 3 to execute one or more cleaning cycle.
[0062] Cleaning cycles have a variable duration, for example from
10 seconds to 30 seconds. The piezoelectric element 36 is excited
by high frequency impulses provided by the control unit 5 so as to
cause rapid vibrations of the shutter 34. In particular, the
shutter 34 rapidly moves up and down and repetitively abuts the
seat 39. Such vibrations promote detaching of the beverage residues
from the surfaces of the same shutter 34 and seat 39.
EXAMPLE 2
Coffee 2
[0063] An amount of 10 g of coffee powder is loaded in the brewing
chamber 2 and pressed by a moveable piston at 4 kg/cm.sup.2. The
piston is then blocked above the coffee powder, within the brewing
chamber.
[0064] Water is heated by powering the water heater 1 until the
temperature sensor measures 80.degree. C.
[0065] An on/off valve, positioned upstream of the brewing chamber
2 is commanded by the control unit 5 to open, thereby allowing the
hot water to enter the chamber 2. At this time the piezoelectric
valve 3 remains closed and the pressure within the brewing chamber
increases up to 10 bar.
[0066] When the pressure of 10 bar within the brewing chamber is
met, or after 2 seconds, the control unit 5 commands the valve 3 to
open. The piezoelectric valve 3 is promptly responsive and the
shutter 34 is rapidly raised a given extent above the seat 39, this
causing the beverage to exit the chamber 2.
[0067] Upon completion of the delivering of the beverage to the
user, the control unit 5 activates the valve 3 for a cleaning cycle
of 5 seconds. During the cleaning of the valve 3 a 5 ml/s flow rate
of hot water is supplied to the empty brewing chamber and through
the same valve 3 for rinsing the related surfaces and optimize
cleaning from residues. Due to the characteristics of the
piezoelectric elements, such as element 36, at least a portion of
the valve body 31 and the shutter 34 are easily vibrated by
powering the same piezoelectric element with proper impulse train.
For each cleaning cycle, the element 36 may be electrically excited
for 5 s, 10 s, 20, s, 30 s, etc. Cleaning cycles may be frequently
provided to avoid build up of residues within the valve 3.
[0068] In other words, piezoelectric valves are operable not only
for allowing control over the machine operation during brewing of
the beverage, but are also operable to provide "self-cleaning"
cycle.
[0069] FIG. 6 shows another piezoelectric valve 50 positioned to
intercept the flow at the exit of the brewing chamber. The valve 50
comprises two plate elements 51, 52 each having a through hole 51',
52' for allowing the beverage to flow through the respective
element. Holes 51' and 52' are not aligned, but are arranged at
opposed sides with respect to the centre of the plate elements.
Element 51, 52 are provided with respective shafts 53, 54 at least
one of which is made of a piezoelectric material. When the valve 50
is closed, plate elements 51 abut the plate element 52. When the
piezoelectric shaft 53 and/or 54 is/are activated, the elements 51
and 52 are separated to the desired extent and a gap is present
between them, as shown in FIG. 6, thereby allowing the flow of the
beverage to exit the brewing chamber 2 toward the discharge 4.
[0070] As alternative to the piezoelectric valve 50, a proportional
electrovalve may be used (FIG. 7). The valve shown in FIG. 7
comprises two disc plates 60 and 61, similar to the plates 51 and
52, having respective slots 60', 61', arranged at the exit of the
brewing chamber 2. The slots 60', 61' are through holes. The disc
plates 60, 61 are positioned one abutting the other. At least one
disc plate 60 or 61 can be rotated by a respective shaft 63, 64 by
an electrically actuated element (not shown). When the slots 60',
61' are mutually arranged as shown in FIG. 7 the valve 50 is
closed. When the disc plates 60, 61 are rotated one with respect to
the other, the slot 60' intercepts, partially or totally, the slot
61', thereby permitting the beverage to exit the brewing chamber 2.
By adjusting the relative rotation of the disc plates 60, 61, i.e.
the extent of superimposition of the slots 60' and 61', it is
possible to adjust the flow rate which is permitted to trespass the
valve 60. It is to be understood that slots 60' and 61' may have a
different shape from the one shown in FIG. 7. For instance slots
60' and 61' can be circular holes. What is important is that the
valve 60 provides for regulating the flow rate by adjusting the
superimposition of the slots 60' and 61'.
* * * * *