Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BEVERAGE DISPENSER
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention pertains to the field of beverage dispensers. More particularly,
the
invention pertains to hot beverage dispensers using liquid concentrate or
materials from
which beverages are extracted by hot water.
DESCRIPTION OF RELATED ART
Embodiments of the invention described below include liquid concentrate and
brewing machines for hot beverages, particularly coffee.
Basically all commercial coffee brewers operate in the same way, where the
difference between one brand to the other is in added features and look. The
brewers have
a water heating tank of 1-2 gallons with high power heating elements of 4-7kw.
They fill
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the tank with water and heat the water to the brewing temp. which is between
180-190°F.
The hot water is pushed out by the increased thermal pressure or by gravity
into the
spraying head which sprays hot water on the ground coffee beans.
This method suffers from numerous disadvantages which result in an imperfect
brewing.
A. Optimal brewing temperature for coffee is 200-205°F. In the current
brewing method
they cannot brew above 180-190°F since the resulting coffee becomes
dangerous
to consume. Drinking hot beverages at temperature above 180°F can cause
serious
mouth burns.
B. The brewing time for 1 to 2 gallons of coffee is of the order of 10 to 15
minutes, which
is too long for optimal extraction. Long extraction time degrades the quality
and
taste of the brewed coffee.
C. Nonuniform extraction due to nonuniform flow of the hot water through the
granular
coffee bed. This effect is referred to as "channeling" - the hot water creates
channels through the ground coffee.
D. Inefficient extraction which results in low soluble and flavor yield.
E. In order to be ready for the next brewing the brewer operator will fill it
with water and
keep the water at brewing temperature (180-190°F) until the next
brewing batch,
which might be few minutes or few hours. When the hot water is sitting in the
water tank for long period of time it depletes its Oxygen and mineral which
degrades the water and therefore the coffee taste.
D. Over time, the deposition of water minerals on the tank walls and heating
elements
builds layers of "stone" which degrades the brewer performance and shortens
its
useful life time.
In the trade, coffee in liquid concentrate form is often called "Liquid
Coffee". The
terms "liquid beverage concentrate" and "liquid coffee" are used
interchangeably in this
application. It will be understood that these terms could also apply to other
liquid
concentrate beverages, such as hot chocolate, espresso, cappuccino, mulled
cider, etc.
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Beverage dispensers using liquid beverage concentrate, which is mixed with hot
water to dispense hot coffee or chocolate or the like are known to the art. US
Patent
3,634,107, "Apparatus for Dispensing Coffee Beverage" is an example of one
such device.
In prior art liquid coffee dispensers, the hot water to be mixed with the
concentrate
is held in large (typically 4-6 gallon) tanks maintained at high temperature.
Water is fed
by gravity from the tank, and is mixed with liquid coffee concentrate at or
near the
dispensing spigot. Incomplete mixing often leads to "stripes" of dark
concentrate and clear
water leaving the spigot, with the beverage variably and incompletely mixing
in the cup.
Hot water drawn out made up by incoming tap water at low temperature, so that
the temperature in the tank varies as the dispenser is used - the more coffee
dispensed, the
lower the temperature, as cool makeup water dilutes the hot water in the tank.
The gravity feed is relatively low in pressure, and this means that it takes
the water
flow a longer time to reach flow equilibrium, during which time the ratio of
concentrate to
water varies considerably from the desired ratio. This results in an
inconsistent coffee
1 S taste.
As the hot water is held, entrained oxygen escapes, and minerals in the water
deposit on the walls of the tank and heating elements, leaving the water
"flat". The flat
water does not release as much aroma from the concentrate as would be
desirable and the
dispensed beverage does not have the desired flavor. The deposited minerals
flake off the
tank walls, putting occasional flakes of mineral in the cup and giving an
"off' taste to the
beverage.
Keeping a beverage dispensing system clean is a key to good-tasting beverages,
yet
prior art machines are not designed to promote easy and regular cleaning.
Such machines are supposed to have a daily cleaning, where plain water is run
through the mix section (only) of the machine. Weekly, the containers of
concentrate
should be removed and replaced with a bag of water and sanitizing chemical, to
clean the
product dispensing part of the machine. In practice, neither is done, and the
beverage and
other contaminants build up on the walls of the tubing, imparting an "off'
flavor to the
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dispensed beverage. At worst there is a possibility of growth of bacteria or
other harmful
organisms in the tubing and dispensing areas.
SUMMARY OF THE INVENTION
The liquid beverage concentrate dispenser of the invention is different from
the
liquid coffee concentrate dispensers on the market mainly in five ways:
1. Incoming high pressure fresh water is heated instantly in a heat exchanger
heated by an
external source of circulating fluid, rather than being heated and stored in a
tank
within the dispenser which is open to the air.
Using an external closed loop heater to heat the incoming high pressure fresh
water instantly, via Heat- Exchanger, has many advantages which improves the
aroma,
look and taste of the dispensed coffee. The advantages are:
~ Since the beverage water is not held, the concentrate is mixed with fresh
hot
water rich in Oxygen, giving an improved aroma.
~ Fresh hot water has no depletion of minerals from deposition on the walls of
a
holding tank, improving the taste.
~ Fresh hot water is supplied at high pressure (typicallyl4-l6psi).
~ Complete mixing with no "stripes" due to the high velocity water flow.
~ An increased heat capacity for the same heater (volume and power), typically
by 30-40 percent. This will allow dispensing larger number of cups per unit
time.
~ An increased of the operating life of the heating element.
~ Using an external water heater eliminates heat leakage from the holding tank
to the liquid coffee concentrate in the machine, allowing the concentrate to
remain at ambient temperature. This increases the liquid coffee's lifetime by
minimizing the thermal degradation of the concentrate.
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2. By accurately mixing concentrate and hot and cold water using a novel
design of a
digital "forward looking" control system to continuously control the liquid
coffee
concentrate pump according to the dispensed coffee flow rate, the invention
permits a very high consistency and accuracy of mixing ratio between the water
5 and the liquid coffee. This improves taste and appearance.
3. In a preferred embodiment, the dispenser has an automatic washing system
which
allows the machine to be completely and effectively washed and sanitized.
4. In a preferred embodiment, each consumer is able to select the dispensed
coffee
temperature, ranging from cold coffee to very hot coffee.
5. In a preferred embodiment, each consumer is able to select the dispensed
coffee
strength.
BRIEF DESCRIPTION OF THE DRAWING
Fig. 1 shows an overall block diagram of an embodiment of the invention.
Fig. 2 shows an overall block diagram of a coffee brewer embodiment of the
invention.
Fig. 3 shows a block diagram of a part of a high-pressure espresso machine
embodiment
of the invention.
Figs. 4a and 4b show arrangements of multiple machines of the invention, as
used with a
single source of circulating hot water.
Fig. 5 shows a flowchart of a method of temperature control of the invention.
Fig. 6 shows a flowchart of a method of automatic cleaning of the machine of
the
invention.
DETAILED DESCRIPTION OF THE INVENTION
The dispenser of the invention allows each consumer to select the dispensed
coffee
temperature according to his or her preference. This differentiating feature
will increase
consumers' satisfaction since it has been established that many consumers
would welcome
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the opportunity to order coffee at a temperature reflecting their personal
preference. Also,
it will reduce the risk of burns from an unexpectedly hot coffee serving.
Figure 1 shows a block diagram of the preferred embodiment of the liquid
coffee
dispenser of the invention.
Incoming water 1 is fed into the machine in a conventional fashion. Normal
"city
water" or "tap water" is supplied at a pressure of typically about 40-80 psi
at a variable,
but cold, temperature of typically 50-60°F or less. If the tap water in
an area is not potable,
it will be understood that the "City Water" term would contemplate the use of
bottled
water or well water instead. The incoming water is filtered 2, preferably in a
conventional
cartridge filter, and input valve 3 allows the fluid supply to be cut off as
needed.
Some pressure regulators require flow in order to regulate pressure at the
output.
Without flow, the pressure at the input and output is the same. If regulator 4
cannot
maintain a regulated pressure without flow, input valve 3 should be closed
between
dispensing. Otherwise, it may remain open or closed as desired.
The input water supply is regulated by a pressure regulator 4 down to
typicallyl6-
psi pressure (depending on the characteristics of valves 7 and 11 and the
required
dispensed coffee flow rate). The flow of water is measured by a flow meter 5,
for purposes
which will be explained below. After the flow meter, the incoming water is
split into two,
or preferably three, branches - one to be heated (controlled by hot water
solenoid valve 7),
20 one for cold water supply (controlled by cold water solenoid valve 11 )
and, in the
preferred embodiment, one to the automatic wash circuit (controlled by wash
water
solenoid valve 25), as will be explained below.
The water to be heated is fed into a liquid-to-liquid heat exchanger 6, where
it is
heated to approximately 180-190°F. The heat supply to the heat
exchanger 6 is a flow of
heated liquid at approximately 210-240°F from an external heat supply
8, comprising a
heater in fluid tank 9 and circulating pump 10. Preferably, the heater is an
electric heater
of 4-7KW capacity, and the tank holds 4-6 gallons of fluid. The pump 10 is
preferably
capable of circulating the fluid at a pressure of 6-lOpsi. Since the
circulating fluid is not
consumed and does not contact the beverage to be dispensed, there is no need
for
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maintaining the sterility of the circulating system, and a non-potable fluid
could be
circulated if desired. Distilled water would be an appropriate fluid, perhaps
with additives
to minimize bacteria growth in the tank.
The location of the large storage tank and heater for the circulating fluid
external to
the dispenser allows the footprint of the dispenser to be significantly
reduced compared to
dispensers which must maintain hot water or beverage internally. This is a
major
advantage in the restaurant market, where countertop space is at a premium.
Because the
source of heat is external to the dispenser, the heat exchanger is the only
part of the
dispenser which gets hot. Therefore, the heat exchanger is preferably well
insulated to
minimize heat leakage to the dispenser, allowing it to remain at ambient
temperature. The
internal design and maintenance of the dispenser is also simplified by
eliminating the need
to design around a large, hot tank, and the fluid in the external tank can be
kept at a higher
temperature, which will increase its heat capacity, than would be desirable or
safe if the
stored hot water was being dispensed as in prior art dispensers.
The hot water from the hot water solenoid valve 7 and the cold water from the
cold
water solenoid valve 11 are joined at a "T" junction 33 into a mixed water
stream. The
valves are preferably fast-acting solenoid valves which can be opened and
closed quickly
under control of the microprocessor controller 30. Preferably, the control of
the valves is
by pulse-width modulation, in which the valves are turned fully on and fully
off, and the
flow is controlled by varying the ratio of "on" and "off' times ("duty
cycle"). By
controlling the duty cycle of valves 7 and 11, any temperature water between
the hot
supply temperature of 180-190°F and the cold supply temperature of 50-
70°F can be
produced at the beverage output (or in the cup by the mixing of pulses of hot
and cold
water). Alternatively, proportional valves could be used at 7 and 11, and the
temperature
controlled by controlling the volume of flow through the valves. This will
enable the
dispensing of not only hot beverages, but also cold beverages.
The temperature of the dispensed beverage could be controllable in a
continuous
range, or discontinuously with a "cold" selection and a range of "hot"
temperatures (say,
130-190°F). The latter system would be simpler, without any loss of
utility, as it is
unlikely that any customer would want "luke-warm" coffee.
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Preferably, the dispenser has two dispensing sections 32a and 32b, for two
beverages (say, regular and decaffeinated coffee), and possibly another for
hot water (not
shown). In the drawing and the following discussion, the identical elements in
each section
are given identical numbers, distinguished by the appended letter, so that
check valve 13a
is in section 32a, check valve 13b is in section 32b, etc. The discussion
below will omit
the letters for clarity's sake. The connections to the controller 30 will not
be individually
discussed, but are shown for clarity. Control lines from the controller 30 to
valves and
pumps are shown as dash-dotted lines -~-, while sensor lines from sensors to
the controller
30 are shown with double dots as -~ .
Although the invention is shown and described herein as it would be
implemented
with two dispensing sections 32a and 32b, it will be understood that the
invention might
be implemented for more than two beverages by adding sections 32c, 32d... etc.
Similarly,
a single-beverage version is produced by omitting section 32b.
In each dispensing section there is a supply of beverage in liquid concentrate
form.
Preferably, this is held in a one-half or one-gallon size "bag in box"
reservoir 12, as is
common to prior art dispensers. The coffee bag in a box is easily replaced
from the front
of the dispenser. These reservoirs keep the concentrate in a collapsible
plastic bag inside a
corrugated cardboard box. As the liquid is drained from the bag, it collapses
within the
box, so that no air vent need be supplied and air does not contact the liquid
to cause any
deterioration of the product prior to consumption. At the outlet of the
reservoir 12 is a
check valve 13, which has a very low forward actuation pressure of, for
example,
approximately O.lpsi, but which will prevent any flow of fluid or air back
into the
reservoir.
Figure 1, section 32a, shows an embodiment of the invention in which a
separate
concentrate pump 17 is used. Figure 1, Section 32b shows an alternate
embodiment where
the concentrate pump 117 is part of the reservoir 12b.
Referring to section 32a, the output of the check valve flows into a multiport
(preferably four-way) junction 15. One of the ports is used to mount a product-
out sensor
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14, which will detect if the reservoir 12 has run dry. This may be a simple
thermistor,
which will heat up when it is not immersed in liquid, or some other sensor
known to the
art. Another port leads to pump 17, and the fourth port is an input for the
automatic
washing system described below, if one is provided.
A positive-displacement pump 17 is used to dispense precise amounts of liquid
concentrate beverage to T junction 34, where it mixes with precise amounts of
controlled
temperature water from beverage valve 18. Pump 17 is shown as being of the
peristaltic
type, but it will be recognized that other kinds of pumps could be used within
the teaching
of the invention, so long as the pump is capable of dispensing a determined
amount of
concentrate.
Section 32b shows an alternate embodiment to 32a, in which the moving part of
the pump 117 is a formed as part of the reservoir 12b, with the solenoid 118
actuating the
moving part of the pump 117..
These
two embodiments differ in the structure of the moving part of the pump, which
may be a
piston, as disclosed in provisional 60/642,311 or a flexible chamber design in
which the
outer part of the chamber moves up and down, as disclosed in 60/682,107.
Additional
split-pump embodiments, in which the moving part is incorporated into the
reservoir and
is actuated by a solenoid in the dispenser, such as diaphragm pumps, bellows
pumps,
oscillating pumps, or other designs are possible within the teachings of the
invention.
The amount of concentrate dispensed by pump 117 can be controlled by pulsing
the solenoid 118, with each stroke of the pump dispensing a known amount of
beverage
concentrate. With the pump I 17 before the T junction 14b, the output which
goes to the
pump in 32a runs to the mixing junction 34b instead. The rest of the
description of section
32a, above is applicable to 32b.
Preferably, the ratio of concentrate to water can be varied, particularly for
cold
beverages, to vary the strength of the dispensed beverage. A variation of
about 10% would
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be preferred, although wider or narrower variation could be chosen as desired
by
controlling the amount of concentrated beverage relative to the amount of
water.
The temperature of the mixed beverage is measured by sensor 20, which allows
the
microprocessor controller to precisely control the temperature of the beverage
by altering
the duty cycle of valves 7 and 11. Since the amount of water entering the
dispenser is
measured by flow sensor 5, and the amount of concentrate is controlled by the
speed of the
peristaltic pump, the microprocessor controller 30 can control the strength of
the beverage
by altering the speed of peristaltic pump 17 or, in the embodiment using pump
117, by
varying the number of strokes per second.
10 Finally, the beverage is dispensed into the cup or container 21 through
spigot 22.
The rapid and turbulent flow through the tubing and spigot create a rapid
equilibrium state
and promote complete mixing of concentrate and water, eliminating "stripes" as
the
beverage is dispensed.
Preferably, a dispensing tray 35 is provided under the spigot 22 area, with a
perforated grid or shelf 36 for the containers to sit upon. The tray is
preferably drained
through a tube 37 to the usual building drains, so that any spilled or over-
filled beverage is
carried away, and to allow the automatic washing system described below to
operate.
In operation of the preferred embodiment of the invention, the consumer
selects
their desired coffee temperature and strength pressing soft buttons on the
touch screen
display 31 of the microprocessor controller 30, and initiates dispensing by
pulling on the
dispense lever 19 on the desired beverage.
Alternately, a dispensing quantity can be set or programmed into the
microprocessor controller 30 or selected from the touch screen 31. This would
be desirable
in behind-the-counter rather than self serve applications, where a pot can be
placed under
the spigot and automatically filled while the wait staff performs other
functions.
In order to achieve a very high accuracy of the dispensed beverage temperature
independent of the cup size, one has to overcome the problem of the cooling of
the trapped
water in the tubes and the cooling of the valve's body by a different amount
between
dispensing sessions, since the time between successive users, and the
temperature chosen
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11
by each user, is random. A preferred embodiment of the invention uses a
computer
controlled digital feedback control system to achieve very high accuracy of
the dispensed
beverage temperature
The temperature control system of the preferred embodiment operates as follows
(fig. S):
70) The temperature of the dispensed beverage T; is measured by sensor 20 at
high rate, for
example at 512 Hz (or every 2 msec.). The dispensed coffee flow rate ~; is
measured continually by measuring the input water flow rate as measured by
flow
meter 5.
71 ) The digital feedback controller multiplies the measured temperature of
the dispensed
coffee by the measured flow rate, times the time interval between two
successive
readings of the temperature sensor 20, giving a temperature-flow quantity t;.
t;=~;xT,x~t
72) The temperature-flow quantity t; is subtracted from what the quantity
should have
been if the dispensed coffee temperature during this short time interval was
equal
to the selected one (T$). The result of this subtraction is stored as an
"error" OE;.
DE;=(T,.x~;O(Tsx~;)=~;x(T-Ty
73) All the "errors" are added up during each period of one cycle of valves 7
and 11.
E, _ ~ DE;
74) If the time period has not elapsed, the method loops back to the beginning
and
measures the flow and temperature again.
75) When the time period is elapsed, the duty cycle of valves 7 and 11 is
changed to
minimize the error, and the method begins again.
For example, in our preferred embodiment the hot valve 7 and the cold valve 11
are pulse width modulated at cycle rate of 2Hz. Therefore the errors are added
up for half
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12
a second. At the end of each half second the duty-cycle of each valve is
recalculated by the
controller code according to the accumulated "error" size and polarity in such
a way as to
minimize the accumulated error in the next half second cycle and bring it to
zero. For
example, if the accumulated error is positive (i.e. the temperature of the
dispensed
beverage is higher than the selected temperature), the duty cycle of the hot
valve will be
decreased and the duty cycle of the cold valve will be increased, and vice
versa.
Using the described method enables the dispensing of beverages at the selected
temperature with accuracy of better then +/- 1%, independent of the cup size.
In addition,
because each cycle is very short compare with the dispensing time the method
achieves
immediate temperature mixing in the cup.
In a preferred embodiment, the dispenser of the invention offers a fully
automatic
computer controlled washing and sanitizing function. This automatic daily
washing and
sanitizing system cleans all the dispenser parts and tubes through which
concentrate coffee
is flowing. The automatic daily washing and sanitizing system prevents build-
up of coffee
deposits on the inner walls of the tubes and valves that encourages the growth
of bacteria
and results in bad tasting coffee. Finally, this system will prolong the life
of the tubes and
provide for labor-free maintenance.
The automatic washing system uses a tank of detergent 23 and a pump 24. The
output of the pump 24 mixes with filtered and regulated input water controlled
by wash
valve 25 in multiport junction 26. The wash valve 25 may be connected to the
cold water,
as shown, or can optionally be connected to the hot water supply The junction
is vented to
the venbdrain output 28 under the control of vent solenoid valve 27. Diluted
detergent in
the output 29 of the multiport junction 26 is connected through check valve 16
to the
multiport junction 15 in each of the beverage sections 32. The check valve 16
preferably
has an opening pressure of 6-l Opsi, which is much higher than the O.lpsi
opening
pressure of check valve 13 on the product reservoir 12, so that the check
valve 16 remains
closed and detergent is not sucked into the system when the dispenser is in
normal
operation. Also to ensure that detergent will not be sucked accidentally into
the system
when the dispenser is in normal operation, the vent valve 27 is always opened
when the
dispenser dispenses beverage.
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The operation of the automatic washing system may be initiated either by a
manual
command at the touchscreen 31, or on a timed basis, set to operate after the
restaurant
using the dispenser has closed for the night.
When the automatic wash cycle is initiated, it performs the following steps
(fig. 6):
80) vent valve 27 is closed and input valve 3 is opened (if it was closed).
81 ) hot water valve 7 and cold water valve 11 are opened to provide hot
water at a safe temperature for washing.
82) dispense valves) 18 are fully opened.
Water now flows through the system, and out the spigots 22 to the
tray 35 and out the drains 37.
83) wash valve 25 is fully opened.
84) pumps) 17 is turned on.
Because the pressure from the water supply through valve 25 ( 14-
l6psi) check valves) 16 open, while check valves) 13 are held closed,
preventing water from flowing backward into the concentrate supply.
Water from the supply runs through valve 25, junction 26, check valves)
16 and peristaltic pump(s)17 to empty through spigots) 22 to the drain 37.
The entire system is now being flushed with clean water. The system may
now wait for a predetermined time for the initial rinse.
85) turn on detergent pump 24.
Detergent is now being pumped from tank 23 by pump 24, diluted
with incoming water from valve 25 in multiport 26, and is flowing through
the check valves) 16 and peristaltic pump(s)17 to empty through spigots)
22 to the drain 37. The detergent pump 24 is left on a predetermined period
of time to sterilize the system.
86) turn off detergent pump 24 to rinse out the system.
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The entire system is once again being flushed with clean water. The
system may now wait for a predetermined time for the final rinse.
87) turn off pumps) 17, wash valve 25, dispense valves) 18, hot valve 7,
and cold valve 11. If desired or required because of the regulator
design, input valve 3 may also be closed in this step.
88) open vent valve 27. If desired, vent valve 27 may be closed after a
chosen period to give the system time to drain.
When the system is restarted, the following steps are performed:
89) if valve 3 was closed in step 87, above, open valve 3.
90) open vent valve 27, if it was closed in step 88, above.
91) turn on pumps) 17 for a time sufficient to prime the lines with liquid
concentrate (a few seconds or revolutions of the pump 17 should be
adequate).
The dispenser is once again ready for operation. Because the vent
valve 27 is open, when pumps) 17 operate the much lower opening
pressure of check valves) 13 cause fluid to be drawn from reservoirs) 12,
rather than. pulling air through the higher resistance of check valves) 16
through the now drained wash system. The vent valve 27 being open, no
detergent can be drawn accidentally into the dispensing system by vacuum
behind check valves) 16.
The washing system of the preferred embodiment is thus made possible through
the "flip/flop" action of the operating pressure of check valves) 13 being
much lower than
the operating pressure of check valves) 16.
The preceding discussion described a single dispenser of the invention.
However,
in commercial operations there might be a need for multiple dispensing
machines. The
external closed-loop heater 8 and heat exchanger 6 system of the invention
lends itself to
such an application.
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1$
As shown in figure 4a, the heated water could be passed through the machines
(65a
through 65e) in series, or, as shown in figure 4b, in parallel. The series
arrangement of
figure 4a would give the same flow rate to all of the machines, but would be
harder to add
or remove machines from the loop. The parallel arrangement of figure 4b would
have a
lower (divided) flow rate in each machine, but putting quick-disconnect
fittings 66a-a and
68a-a on supply plenum 67 and exhaust plenum 69, respectively, would make it
easy to
add or remove machines without disrupting the flow of hot water through the
other
machines.
Commercial Coffee Brewer Embodiment
Figure 2 shows a commercial coffee brewer using the heat exchanger and
controls
from the liquid coffee embodiment of the invention. The individual elements in
figure 2
which are the same as in figure 1 are given identical reference numbers, and
the
description of figure 1, above, may be referred to for the details and
operation of these
elements.
1$ Using the external closed-loop heater 8 to heat the incoming high pressure
fresh
water instantly via heat exchanger 6 and microcomputer controller 30, which
controls the
hot water temperature system, can overcome the disadvantages of current coffee
brewers
which were described above. The result will be a superior coffee brewer which
will brew
high quality coffee with much higher cup yields per pound of coffee.
High pressure incoming fresh water 1 (typically city water at 70-80 psi) is
regulated by the (preferably computer controlled) pressure regulator 4 down to
the desired
pressure, and heated to the extraction optimal temperature (195-20$°F)
in heat exchanger
6. The output hot water from heat exchanger 6, controlled by hot water
solenoid valve 7 is
joined with incoming cold water controlled by cold water solenoid valve 11 in
T junction
2$ 33. By reading the temperature at the outlet through temperature sensor 20
and the
incoming water flow rate through flow meter S, the controller 30 can vary the
duty cycle
of valves 7 and 11 to provide precise control of the brewed coffee
temperature. The
controlled temperature water is supplied to the spraying head 40 in brewer
enclosure 41.
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A second temperature sensor 49 is preferably installed in the coffee ground
basket
42 and is used by the controller to measure the temperature of the coffee
ground (cake).
This will enable the controller to better optimize the extraction temperature
which will
improve the cot~ee test, aroma and soluble yield.
The holding basket 42 with the ground coffee beans 43 will be sealably mounted
to
the brewer chamber 41 forming a high pressure seal 44 around the spraying head
40. The
brewed coffee passes out the bottom of the basket 42 into the pot 45,
preferably sitting on
a heater 46.
Because of the high pressure of the hot water, the hot water from the spraying
head
40 will be pushed by the water pressure through the ground coffee beans 43 in
a short time
(typically 1-3 minutes at a rate of O.Sgal/min or higher). It will also allow
using finely
ground coffee beans, which will increase the extraction efficiency. The high
pressure,
time, uniform flow through the grind bed, finely ground coffee beans, optimal
temperature
and the short brewing time will improve the soluble extraction yield and
result in high
quality coffee.
Using our digital feedback control system (as was explained before) to control
the
dispensed coffee temperature there are at least three method of extraction
A. In order to dispense coffee at the selected temperature, the brewer may
inject
very hot water (200-210°F) and cold water (50 -70°F) in short
pulses. For example; hot
water for 8 sec. and cold water (60°F) for 2 sec., repeating until the
brewing is completed.
This mode of operation also has the advantage that the actual brewing time is
composed of
many very short brewing periods.
B. A second possible mode of operation is to program the hot water temperature
profile as a function of time. For example; starting very hot to heat up the
ground coffee to
the extraction temperature in a short time, and then lowering the water
temperature in such
a way that the brewed coffee temperature will be at the selected temperature.
C. A third possible method of controlling the brewed coffee temperature is to
keep
the hot water solenoid open and control the duty cycle of the cold water
solenoid valve 11
to provide brewed coffee at the selected temperature.
CA 02549742 2006-06-09
17
The high pressure brewer of the invention will allow the optimization of the
brewing parameters i.e pressure, temperature, brewing time and brewing mode to
achieve
a high quality coffee and a high efficiency extraction. This will increase the
cup yield over
existing coffee makers.
In order to achieve high consistency and accurate proportions between the
coffee
ground and water, an automatic coffee grinder 34 is preferably attached to the
brewer. The
brewer computer base controller will also control the operation of the
grinder. When the
brewer operator selects a batch size and coffee strength, the controller will:
(a) control the
operation of the grinder to grind the correct amount of coffee beans 48 at the
correct grind
size into basket 42, and (b) optimize the extraction time to the selected
batch size and
grind size, by adjusting the water pressure via pressure regulator 4.
Adjusting the water pressure as a function of the batch size and grind size is
desirable in order to optimize extraction time. This is due to the fact that a
thinner layer of
ground coffee beans presents less resistance for the water to flow through
then a thicker
layer. In addition, a fine grind size presents more resistance then a coarse
grind size.
Espresso Machine Embodiment
Current commercial and domestic espresso machines are very expensive. The main
reason is that espresso machines operate at high pressure. Therefore
conventional espresso
machines must be built with water heating tanks capable of holding the high
pressure. This
requires an expensive water tank made of thick stainless steel walls, and all
the ports must
be designed for high pressure. Additionally, hot water sits in the tank for
many hours,
resulting in depletion of minerals as they are deposited on the water tank
walls. Depleting
the minerals from the water degrades the coffee taste. Deposition of minerals
on the water
tank walls, sensors and heating elements results in shortened life of the
heater and
degradation of machine performance
The espresso machine embodiment of the invention is shown in figure 3. The
individual elements in figure 3 which are the same as in figures 1 and 2 are
given identical
reference numbers, and the descriptions of figures 1 and 2, above, may be
referred to for
the details and operation of these elements.
CA 02549742 2006-06-09
I8
As in the other embodiments, incoming city water 1 is filtered 2, pressure
regulated
4 and metered S. The water is heated in heat exchanger 6, which in this
embodiment is fed
from external heater 8 with heated fluid at 190-220°F. This heats the
water to 200-205°F,
and it is fed to a number of brewing station solenoid valves SOa, SOb, SOc,
which control
dispensing of the heated water to associated brew stations.
One brew station is shown, in which hot water is supplied at high pressure up
to 80
psi or higher, depending on the city water pressure, to the spraying head 40.
The holding
basket 42 with the ground coffee beans 43 will be mounted to the brewer 41
forming a
high pressure seal 44 around the spraying head 40. The espresso passes out the
bottom of
the basket 42 into the espresso cup 60.
A steam chamber station 53 provides steam for steaming milk in the espresso.
At
the demand for steam, valve S1 is opened and hot water is injected through the
shower
head 52 onto a hot ( >220°F) evaporating plate 57, heated by electric
heating elements 54,
which will evaporate part of the hot water and create steam. Valve 51
preferably has high
resistance to water to flow through (ie very small opening) , so that there
will be a large
pressure drop across the valve, and the water is sprayed on the evaporating
plate at a
relative low pressure compared to the supply pressure.
The steam will start to build pressure in the chamber, when the pressure will
reach
the cracking pressure of check valve 56 it will start to flow out into the
steam pipe 58 in
cup 61. At the end of the steam cycle valve 51 will close, the pressure will
drop, and check
valve 56 will close, which will stop any remaining steam in the chamber from
exiting. The
water that will not turn to steam can be drained from the bottom by opening
the drain
valve 55.
In order to have an instant supply of steam, the evaporating plate 57
preferably has
two heating elements 54 in parallel. The first is a low power heater can be on
all the time,
and will keep the evaporating plate 57 at a high temperature. The second
heating element
would be a high power heater, which supplies the needed energy to evaporate
the water,
which will be turned on only during the time when steam is dispensed. The high
power
heater can be turned on when valve 51 is opened, and turned off when the valve
is closed.
CA 02549742 2006-06-09
19
Alternatively, the high-power heater could be thermostatically controlled, or
a single
heater could be used.
Using the external closed-loop heater of the invention to heat the incoming
high
pressure fresh water instantly, has the following advantages over prior art
espresso
machines:
A. Lower cost due to elimination of the expensive high pressure water tank.
B. By supplying fresh, high quality hot water, the problems of deposition and
depletion of
minerals are avoided, resulting in improved coffee taste and logner operating
lifetime.
C. Operation at a higher pressure shortens the extraction time.
D. Elimination of the water tank permits a machine to be designed with a
smaller
"footprint".
In order to achieve high consistency and accurate proportions between the
coffee
grounds and water, an automatic coffee grinder may be attached to the espresso
machine,
as discussed in the embodiment of figure 2, above.
In the claims, it will be understood that when one element is recited as
"coupled" to
another, that this coupling may be direct, or there may be other elements
between the
recited elements, all such variations intended to be within the scope of the
claim.
Accordingly, it is to be understood that the embodiments of the invention
herein
described are merely illustrative of the application of the principles of the
invention.
Reference herein to details of the illustrated embodiments is not intended to
limit the
scope of the claims, which themselves recite those features regarded as
essential to the
invention.
CA 02549742 2006-06-09
Listing of Reference Numbers
1 City Water (tap water) supply31 Touchscreen
35
2 Input water filter 32a/b Beverage station
1/2
3 Input Valve 33 T junction mixing hot
and cold water
5 4 Water Pressure Regulator 34 Coffee Grinder (fig.
2)
5 Flow Meter 35 Dispensing tray
6 Heat Exchanger 40 36 Drain board
7 Hot water Solenoid Valve 37 Overflow Drain for tray
8 External circulating hot 40 Shower head (figs. 2/3)
water supply
10 9 Hot water heater 41 Brew chamber (figs.
2/3)
10 water circulating pump 42 Holding basket (figs.
2l3)
11 Cold water Solenoid Valve 43 Coffee beans (figs.
45 213)
12a/b Beverage 1/2 concentrate44 Seal (figs. 2/3)
13a/b Beverage 1/2 concentrate45 Pot (fig. 2)
Check
15 Valve 46 Pot heater (fig. 2)
14a/b Out-of product sensor 4g Coffee beans (fig. 2)
- Beverage
1/2 concentrate
1/2 50 49 Brew basket temp.sensor
(fig. 2)
15a/b Multiport junction -
Beverage
l6aJb Detergent Check Valve SOa-c Espresso brew valves
- Beverage (fig. 3)
20 1/2 51 Steam valve (fig. 3)
17/117 Pump - beverage 1/2 52 Steam shower head (fig.
3)
18a/b Beverage 1/2 Dispense 53 Steam chamber (fig.
Valve 3)
19a/b Beverage 1/2 dispensing 54 Heating elements (fig.
lever 55 3)
20a/b Temperature Sensor - 55 Steam chamber drain
Beverage 1 /2 valve (fig. 3)
21a/b Beverage cup 1/2 56 Steam check valve (fig.
3)
22a/b Beverage 1/2 dispense 57 Evaporation plate (fig.
outlet 3)
23 Detergent tank 58 Steam outlet (fig. 3)
24 detergent low flow pump 60 Espresso cup (fig. 3)
60
25 wash water Solenoid Valve 61 Espresso cup for steaming
(fig. 3)
26 Detergent mixing multiport 65a-a Beverage machines
junction (fig. 4)
27 Air vent Solenoid Valve 66a-a quick disconnects
(fig. 4)
28 Vent/Drain 67 Supply Plenum (fig.
4)
29 Wash line 65 68a-a quick disconnects
(fig. 4)
30 Microprocessor controller 69 Supply Plenum (fig.
4)
118 Solenoid for valve
117 (figure 1)
