Note: Descriptions are shown in the official language in which they were submitted.
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
METHOD AND DEVICE FOR BREWING BEVERAGES
FIELD OF THE INVENTION
The present invention concerns a method and device for brewing beverages. It
has
particular utility in brewing plain coffee, espresso, cappuccino, and similar
beverages,
but may be used to brew any sort of beverage.
BACKGROUND OF THE INVENTION
Brewed beverages prepared by mixing, steeping, soaking, or boiling a brewing
material in water or other brewing liquid have been known for quite some time.
For
example, coffee may be made by passing hot water through ground coffee beans,
and
tea may be made by seeping crushed tea leaves in hot water. Similarly, brewing
materials may be a liquid, such as liquid creamer or chocolate. More
generally,
brewing material may include an extractable solid, liquid, powder, concentrate
or
other material used in a brewing operation. As used herein, the tenn "coffee"
includes not only plain coffee, but also coffee in all its other forms such as
for
example espresso, cappuccino, mocha, decaffeinated coffee, and the like. The
art of
preparing such brewed beverages has improved over time. Nonetheless, known
coffee brewers which brew ground coffee beans under pressure to make coffee
suffer
from several drawbacks.
For example, known heaters used in such devices have included relatively large
reservoirs for holding a brewing liquid as it is being heated, with a maximum
capacity
of about 300 to 350 ml of brewing liquid. Because these known reservoirs hold
a
relatively large amount of water, it takes a long time to heat the water up at
the
beginning of the brew process. This drawback is particularly acute when a
sufficient
amount of time has passed since the previous brew that the temperature of the
water
in the reservoir has decreased all the way to room temperature, thus requiring
a "cold
start." In some known machines this leads to a long pre-brew heating process
which
can last 90 seconds or more, before coffee can actually be brewed. This causes
a long
wait for the user to get his or her coffee. These known units further
incorporate a
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
2
coiled heating element which is disposed at one end of the heater, remote from
the
other end.
Known brewing devices have also heated a brewing liquid by disposing heating
elements on the outside of delivery conduits carrying a flow of brewing
liquid. Thus,
in these devices, the brewing liquid is heated as it flows from a storage
reservoir to
the brewing chamber. The portion of the delivery conduits where the brewing
liquid
is heated in these devices may have a maximum storage capacity of only about
10 to
15 ml of brewing liquid. Because of those small storage capacities, these
heaters have
a relatively fast heat up time.
However, heating such relatively small amounts of water at one time increases
the
difficulty of controlling the temperature of the brewing liquid during a
brewing
operation. Brewing liquid temperature is controlled by feedback from a
temperature
sensor, but it takes some amount of time for the sensor to react to the
temperature of
the brewing liquid and provide a signal to a system controller indicative of
brewing
liquid temperature. By the time that signal is transmitted, the brewing liquid
temperature has changed again -- which happens quickly because of the small
volumes involved -- and the controller acts on old information. This
temperature
sensor measurement time lag makes reaching an optimal steady state brewing
liquid
temperature difficult in small volume capacity heating reservoirs.
Cleaning out spent brewing material from the brewing chamber after a brewing
operation is complete can often be a messy process. Typically the spent
brewing
material is left as an excessively wet mass of material contained in a flimsy
piece of
filter material or filter pod, which can be difficult to pry out of a brew
basket or other
container forming the brewing chamber.
Some current brewing systems generate steam near the end of a brewing
operation as
part of a purging process. These known systems, however, are very inefficient
in that
they have little or no control over the amount of the steam generated. They
attempt to
control the amount of steam generated by metering a supply of water to a
heater to be
boiled. However, these known devices use small heating chambers for the
boiling
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
3
operation. This allows an appreciable amount of unvaporized water to be
carried
along with the steam through the system, which is disadvantageous. Also, the
amount
of steam generated is variable from brew to brew, leading to unknown amounts
of
steam and brewed beverage being created.
Known prior brewing devices principally rely on varying the power of a heating
element to control the temperature of the brewing liquid. Such systems result
in a
time delay between detecting the need for a temperature change and effecting a
temperature change. That time delay is due to the slow response time between
changing the voltage of the heating element, and that changed voltage actually
resulting in a change of outputted power by the heating element. The heating
element
will have some resistance to changes in power, which it takes time to
overcome.
SUMMARY OF THE INVENTION
A heater which is particularly useful in coffee brewers and other brewing
devices is
disclosed. The heater comprises a body forming a heating reservoir having an
inlet
for a brewing liquid to enter the heating reservoir and an outlet for the
brewing liquid
to exit the heating reservoir. The heating reservoir has a volume capacity for
storing
brewing liquid. One or more heating elements are disposed in or near the body
for
heating the brewing liquid disposed in the heating reservoir, and a source of
voltage
controls a power of the one or more heating elements. The volume capacity of
the
heating reservoir and the power of the one or more heating elements are
selected so as
to have a watt density of no less than about 6 watts per milliliter and no
more than
about 30 watts per milliliter. The heater design permits a fast heat up time,
while at
the same time allowing good control of the brewing liquid temperature leaving
the
heater. It also can lead to fast overall brewing times, on the order of 90
seconds to
brew a seven ounce cup of black coffee from a cold start.
Also disclosed is a brewing device. The brewing device comprises a pump having
a
pump inlet and a pump outlet, with the pump inlet being fluidically connected
to a
reservoir of brewing liquid to pump the brewing liquid at a flow rate. A
heater
comprises a heater body and a heating element. The heater body forms a heating
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
4
reservoir and has a heater inlet and a heater outlet. The heater inlet is
fluidically
connected to the pump outlet. The heating element is disposed in or near the
heating
reservoir for heating a brewing liquid in the heating reservoir. The heating
reservoir
having a volume capacity. A temperature sensor for measuring the temperature
of the
brewing liquid has a measurement lag time. The flow rate, the heating
reservoir
volume capacity, and the temperature sensor measurement lag time are chosen so
that
a residence-to-lag time ratio is no less than about 2 and no more than about
10. A
brewing chamber holds a supply of coffee to be brewed by the brewing liquid,
with
the brewing chamber having a chamber inlet and a chamber outlet. The chamber
inlet
is fluidically connected to the heater outlet by a liquid flow path. A
dispensing outlet
is fluidically connected to the chamber outlet. The heater design permits a
fast heat
up time, while at the same time allowing good control of the brewing liquid
temperature leaving the heater.
Also disclosed is a brewing and purging process in a brewing device,
comprising
placing a brewing material in a brewing chamber of the brewing device,
operating a
heating element disposed in or near a heating reservoir to heat a supply of
brewing
liquid, which includes at least some amount of water, operating a pump to
pressurize
the brewing liquid, and using the pressurization to pass the heated supply of
brewing
liquid through the brewing material to perform a brewing operation, and after
the
brewing operation is complete, deactivating the pump and setting a power of
the
heating element so that a portion of water in the heater becomes steam, and
generating
the steam for a pre-determined amount of steam time, and passing the steam
through
the brewing material in the brewing chamber. The purging process at least
partially
dries spent brewing material in the brewing chamber, thus making it easier to
clean
out of the brewing chamber. The purging process also permits a high degree of
control and repeatability of the steam generating process. The purging process
may
advantageously be used with the heater design, because the smaller storage
capacity
of the heater makes generating steam easier and more efficient.
Also disclosed is a method of brewing a brewing material in a brewing device,
comprising placing the brewing material in a brewing chamber of the coffee
brewing
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
device, operating a heating element disposed in or near a heating reservoir to
heat a
supply of brewing liquid, operating a pump to pressurize the brewing liquid,
and
using the pressurization to pass the heated supply of brewing liquid through
the
brewing material to perform a brewing operation, and adjusting a flow rate of
the
brewing liquid during the brewing operation to control a temperature of the
brewing
liquid. This method permits a fast time response between detecting the need
for a
temperature change and effecting a temperature change, thus improving the
overall
brewing process.
These and other advantages of the present invention will become more apparent
from a
detailed description of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, which are incorporated in and constitute a part
of this
specification, embodiments of a brewing method and device are illustrated.
These
drawings, together with the general description of the brewing method and
device given
above and the detailed description given below, serve to example the
principles of this
invention.
Figure 1 is a top perspective view of one embodiment of a brewing device
including a
closure mechanism, a reservoir, a brewing unit and a drip tray.
Figure 2 shows several different elements of a representative brewing system.
Figure 3 is a perspective view of a manifold including a temperature sensor, a
pressure relief valve and a vacuum vent valve.
Figure 4 is a side view of one embodiment of a heater for use in a brewing
device.
Figure 5 is another side view of the heater shown in Figure 4.
Figure 6 is a cross-sectional view of the heater shown in Figure 4, taken
along the line
6-6 in Figure 4.
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
6
Figure 7 is a cross-sectional view of the heater shown in Figure 4, taken
along the line
7-7 in Figure 5.
Figure 8 is a graph illustrating a watt density property of heating systems
used in
brewing devices.
Figure 9, like Figure 6, is a cross-sectional view of the heater shown in
Figure 4 taken
along the line 6-6 in Figure 4, but shows a supply of brewing liquid disposed
within
the heater.
Figure 10 is a schematic representation of a brewing device including a
controller
which may perform a temperature control process.
Figure 11A is a flowchart showing a temperature control process.
Figure 11B is a flowchart showing a temperature control process.
Figure 12 is a flowchart showing a purging process.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to the drawings in which like numerals designate like parts
throughout
the various views, preferred embodiments of a brewing method and device are
shown.
Figure 1 shows one embodiment 10 of a brewing device. The brewing device 10
includes a storage reservoir 12 for holding a supply of brewing liquid such as
water, a
brewing unit 14 in which the brewed beverage is prepared, and a drip tray 16.
The
storage reservoir 12 is shown as a separate component from the brewing unit
14, but
may of course be alternatively disposed within the brewing unit 14. The
brewing unit
14 may include a release handle 17 for releasing a closure mechanism 18, a
dispensing outlet including a spout 20 for dispensing a brewed beverage, and
one or
more operational control switches 22 to control aspects of the brewing
operation.
Such aspects may include for example duration of brewing and amount of brewed
beverage to dispense. The storage reservoir 12 has a removable lid 12a to
facilitate
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
7
refilling the storage reservoir 12 with a brewing liquid. In Figure 1, the
closure
mechanism 18 is shown in a closed position.
In operation, the brewing device 10 uses a supply of brewing liquid from the
storage
reservoir 12 in a brewing operation within the brewing unit 14 to produce a
brewed
beverage such as coffee. The brewing device 10 then dispenses the brewed
beverage
out of the spout 20 and into a cup or other receptacle disposed on or over the
drip tray
16. To accomplish this, various fluid conduits are present in the brewing
device 10 to
form a brewing liquid supply line, as will be understood by one of ordinary
skill in the
art. The drip tray 16 catches and holds brewed beverage which may be
accidentally
dispensed through the spout 20 without a cup or receptacle disposed underneath
it, or
which may spill from the cup or receptacle.
Typically the brewing material is disposed in a brewing chamber (not shown)
within
the brewing unit 14. Usually the brewing material is placed in the brewing
chamber
on top of one or more pieces of filter material, or entirely disposed within a
surrounding filter material pod which is inserted as a unit into the brewing
chamber.
Whatever its form, the filter material operates to contain the brewing
material within
the filter chamber throughout the brewing process, while permitting brewed
liquid to
pass through the filter material and out the spout 20. Thus the brewing
material is
prevented from entering the user's cup or clogging up the system downstream of
the
brewing chamber. When pods are used, they may advantageously contain more than
one brewing material. For example, a first chamber of the pod can contain
ground up
coffee and a second chamber can contain millc, thus creating a latte as a
brewed
beverage. The term "milk" as used herein includes all forms of milk and milk
substitutes, in whatever form, such as for example whole milk, skim milk, raw
milk,
pasteurized milk, condensed milk, dry milk, evaporated milk, powdered milk,
cream,
half-and-half, buttermilk, and the like. Sugar or other brewing materials may
also
advantageously be placed in a pod. The brewing chamber may be formed by a brew
basket which is removable from the brewing unit 14 to allow cleaning and
maintenance operations to be performed.
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
8
A brewing system 100 may incorporate several different elements, and Figure 2
shows a representative set of such elements. The solid boxes and arrows in
Figure 2
represent components which are meant to carry or process brewing fluid. The
solid
arrows thus represent flexible tubes, or passageways defmed by one or more
rigid
structures, or a combination of both tubing and rigidly formed passageways,
which
are capable of holding liquid. The dotted boxes and arrows in Figure 2
represent
components which are meant to carry or process air.
The brewing liquid may be stored in a storage reservoir 101, such as the
storage
reservoir 12 of the brewing device 10 shown in Figure 1, before the brewing
operation begins. By action of gravity or perhaps a pump 104, the brewing
liquid
passes from the storage reservoir 101 through a flow meter 102 to reach the
pump
104. The flow meter 102 measures the flow rate of the brewing liquid. That
flow rate
may be used, for example, by an electronic controller within the brewing
device 10 to
monitor and control the brewing process. For example, it can be used to
determine
whether the storage reservoir 101 is out of brewing liquid, for in that event
the flow
rate would be zero. Such a flow meter may be obtained AWECO Appliance Systems
in Neukirch, Germany.
The pump 104 pumps the brewing liquid under pressure to and through a heater
106
to reach a brewing chamber 108, such as the brewing chaniber of the brewing
device
10. A representative pump for this application is a vibration pump which may
be
obtained from ULKA Srl in Pavia, Italy as Model ER Type EP8R.
Once the brewing liquid is heated by the heater 106 to a desired temperature,
it travels
to the brewing chamber 108 where it is mixed, steeped, soaked, boiled or
otherwise
brewed with a brewing material in order to make a brewed beverage. The brewed
beverage is then dispensed from the brewing device, typically under the force
of
gravity or pressure supplied by the pump 104. The brewed beverage may
advantageously be dispensed from a spout 109, such as the spout 20 of the
brewing
device 10, to fall into a cup, pot or other receptacle for consumption.
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
9
The representative embodiment of Figure 2 has several elements disposed within
or
fluidically connected to the fluid flow path 111 between the heater 106 and
the
brewing chamber 108. A temperature sensor 110 such as a thermister 500 may
measure the temperature of the brewing liquid as it passes from the heater 106
to the
brewing chamber 108. A thermister 500 is an electrical resister made of a
material
having an electrical resistance which varies in a known and well-defined
manner with
temperature. Those temperature measurements may be used by an electronic
controller within the brewing device 10 to monitor and control the brewing
process.
For example, the measurements can be used to determine whether the heater 106
is
over- or under- heating the brewing liquid, and consequently whether the power
of a
heating element in the heater 106 should be increased or decreased, or if the
brewing
liquid flow rate should be changed.
The representative embodiment of Figure 2 further includes a pressure relief
valve
112 and a vacuum vent valve 114 fluidically connected to the fluid flow path
111
between the heater 106 and the brewing chamber 108. The pressure relief valve
112
is a check valve which ensures that the pressure within the brewing system 100
downstream of the pump 104 does not exceed a predeterniined maximum value for
safety or good brewing purposes, such as 20 psi. Thus the pressure relief
valve 112 is
normally in a closed position, not permitting liquid or air to pass through
it. However,
the pressure relief valve 112 opens if and when the pressure within the fluid
flow path
111 exceeds the predetermined maximum value. In the event the pressure relief
valve
112 does open, the brewing liquid is permitted thereby to pass out of the
fluid flow
path 111, preferably back to the storage reservoir 101 where it can be
collected.
Although not shown in Figure 2, the brewing liquid escaping through the
pressure
relief valve 112 may alternatively be led out to the atmosphere 116, or to the
drip tray
16, or anywhere else to relieve the fluid flow path 111 of pressure built up
downstream of the pump 104.
The vacuum vent valve 114 connects the surrounding atmosphere 116 to the
brewing
system 100. The vacuum vent valve 114 is a check valve which opens to let air
into
the brewing system 100 if the pressure within the system drops far enough
below
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
atmospheric pressure by some minimum pressure differential, for example 0.2
psi.
This typically occurs near or at the end of a brewing cycle, when the pump 104
stops
applying pressure and steam left over in the system 100 begins to condense.
This
decreases the pressure within the system 100. Opening of the vacuum vent valve
114
prevents any liquid remaining in the brewing chamber from being drawn back
into the
line 111 by vacuum pressure.
Figure 3 shows a manifold 118 which advantageously incorporates, in a single
modular component having a rigid structure, a temperature sensor 110, a
pressure
relief valve 112, and a vacuum vent valve 114. Thus a rigid central tube 120
has an
inlet end 122 and an outlet end 124 opposite the inlet end 122. A first
flexible tube
may be connected to the inlet end 122 to bring heated brewing beverage from a
heater
106, and a second flexible tube may be connected to the outlet end 124 to
carry heated
brewing beverage to the brewing chamber 108. The ends 122, 124 may be flanged
as
shown in Figure 3 to facilitate a sealed connection with the flexible tubes.
Rigid tube connectors 120a, 120b and 120c respectively connect the temperature
sensor 110, pressure relief valve 112, and vacuum vent valve 114 to the
central tube
120. Electrical connectors (not shown) may extend away from the temperature
sensor
110 to an electronic controller. A flexible tube or other conduit may be
connected to
an outlet end 136 of the vacuum vent valve 114 to lead to the atmosphere 116
or other
air supply.
In the embodiment of Figure 3, the pressure relief valve 112 includes a lower
valve
body 126 attached to an upper valve body 128 to form a valve cavity sealed
with an
0-ring 130. The 0-ring 130 may be made of a suitable sealing material such as
rubber or silicone rubber. A valve member 132 is disposed within the valve
chamber,
and is normally urged by a spring 134 to a closed position preventing brewing
liquid
from leaving the tube 120 through the valve 112. The valve member 132 may
advantageously be made of silicone rubber. A flexible tube or other conduit
may be
connected to an outlet end 138 of the pressure relief valve 112, to carry
expelled
liquids back to the reservoir 101 or some other place for expelling liquid.
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
11
The manifold 118 may, of course, be configured in several ways which are
different
from the representative embodiment shown in Figure 3. For example, if it would
be
desirable for the manifold 118 to take up less space, the manifold 118 could
incorporate a 90 bend in the central tube 120 at the point where it
intersects with the
tube connector 120a. It will also be appreciated that one or more of the
temperature
sensor 110, pressure relief valve 112, and vacuum vent valve 114 may not be
part of a
manifold 118. For example, the manifold 118 may include only the pressure
relief
valve 112 and vacuum vent valve 114, with the temperature sensor 110 disposed
elsewhere in the brewing system 100. Moreover, the order and spatial
configuration
of the various components in the manifold 118 as shown in Figure 3 does not
have
any special significance. Thus the components may alternatively be disposed
all on
one side of the central tube 120, in a single row. Or, the temperature sensor
110 may
be disposed upstream of the two valves 112, 114. It will thus be appreciated
that
various options are available in forming a manifold 118 for use in a
particular brewing
device. Use of a manifold 118 advantageously eliminates several fluidic
connection
points between flexible tubes and rigid structure (such as the connection at
the ends
122, 124), thus reducing the chance of developing a leak. For example, the
junction
between the valves 112, 114 and the temperature sensor 110 does not have any
connection points.
Figures 4-7 show one embodiment of a heater 106. The heater body 140 defines a
heating reservoir 142 including an inlet 144 to the heating reservoir 142 and
an outlet
146 from the heating reservoir 142. The illustrated body 140 is of an
elongated,
generally cylindrical or oval shape, but any shape is possible. Flexible
tubing may
carry brewing liquid under pressure from the pump 104 to the inlet 144. Other
flexible tubing may carry brewing liquid away from the heater outlet 146 to be
taken
to a brewing chamber. The inlet 144 and outlet 146 may be disposed at or near
opposite ends of the heater 106, as shown for example in Figures 4-7. Brackets
154
may be used to mount the heater 106 within a brewing unit 14. The heater 106
may
have a storage capacity of about 100 ml of brewing liquid.
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
12
The heating reservoir 142 houses a coiled cal rod heating element 148.
Contacts 150,
152 extend outside of the reservoir 142 to be electrically connected to a
voltage
source, perhaps controlled by an electronic controller. Although the heating
element
148 is shown disposed inside the heater body 140, it may alternatively be
disposed on
or near the exterior of the heater body 140. Varying the applied voltage to
the heating
element 148 changes the power output of the heating element 148, and therefore
changes the temperature of the heating element 148. Heat generated by the
heating
element 148 is transferred to the brewing liquid to heat it up. Heating
element power
is discussed fiirther below.
The heating reservoir 142 has a length dimension L along a first axis, and a
width
dimension W along a second axis which is perpendicular to the first axis, such
as
shown for'example in Figure 6. The heating element 148 has a maximum length
dimension Z which extends along the first axis, as shown for example in Figure
6.
The maximum length Z is preferably at least one-half of the length L, more
preferably
is at least three-quarters of the length L, and most preferably is
substantially the same
as the length L. Similarly, the heating element 148 has a maximum width
dimension
w which extends along the second axis, as shown for example in Figure 6. The
maximum width w is preferably at least one-half of the width W, more
preferably is at
least three-quarters of the width W, and most preferably is substantially the
same as
the width W. The heating element 148 additionally has a maximum coil dimension
C,
illustrated in Figure 6, corresponding to the maximum diameter of the coils in
the
heating element along the first axis. The maximum coil dimension C is
preferably at
least one-half of the length L, more preferably is at least three-quarters of
the length
L, and most preferably is substantially the same as the length L.
The heater body 140 may include one or more receptacles 156 to receive a
resettable
thermal cut off or a permanent thermal cut out. Such devices are conventional.
They
could be mounted to the outside of the heater body 140, such as in a
receptacle 156, to
sense the temperature of the brewing liquid indirectly through the temperature
of the
body 140. Or, they may be disposed inside the body 140 itself, to sense the
temperature of the brewing liquid directly.
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
13
A conventional resettable thermal cut off has a temperature sensor and a
circuit
breaker. In the event the temperature sensor exceeds a predetermined value,
for
example 120 Celcius, the circuit breaker breaks the circuit providing power
to the
heater 106, thus shutting it down. The thermal cutoff may, of course, be
connected to
an electronic controller to shut down the entire brewing process at the same
time.
Once the temperature of the heater 106 drops below the predetermined value,
the
circuit breaker closes and thus permits the heater 106 to turn back on and /
or permits
a brewing operation to continue. Such a resettable thermal cut off is useful
to ensure
the brewing liquid is not too hot to produce satisfactory beverages, or for
safety
purposes to ensure the brewing liquid does not get hot enough to cause damage
to the
system.
A conventional pernmanent thermal cut out (often called a thermal fuse), like
a
resettable thermal cut off, has a temperature sensor and a circuit breaker.
However,
the permanent thermal cut out is not resettable. Thus, at some predetermined
temperature the circuit breaker permanently prevents power from being supplied
to
the heater 106. Such a temperature might be, for example, 216 Celsius. A
permanent thermal cut out is typically used for safety purposes to ensure the
heating
system does not get hot enough to cause damage. It may be used as a back-up
mechanism for a resettable thermal cut off, where the permanent thermal cut
out is set
to operate at a higher temperature than the resettable thermal cut off.
The same results can of course be alternatively obtained with a temperature
sensor,
such as a thermister 500, disposed on or in the heater body 140 in combination
with
an electronic controller. In this scenario, the electronic controller operates
as the
circuit breaker. But the electronic controller can additionally use the
temperature
information received from the thennister 500 in other parts of a brewing
operation.
For example, the temperature information may be used to determine when the
brewing liquid in the heater 106 is hot enough to begin a brewing process, or
has
reached a boiling point to generate steam.
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
14
As discussed above, a relatively large volume capacity heating reservoir can
lead to
long start-up times for the brewing process. On the other hand, a relatively
small
volume capacity heating reservoir can lead to difficulties in controlling the
temperature of the brewing liquid during a brewing operation. It is believed a
heating
reservoir volume capacity of between about 50 ml and about 150 ml, or more
preferably between about 75 ml and about 125 ml, and most preferably of about
100
ml, is advantageous.
In addition, when trying to optimize a heater for use in a brewing device, the
power of
the heating element can be considered along with heating reservoir volume
capacity.
Heating elements are often rated by their maximum wattage output. Typical
ratings
of heating elements used in brewing devices range from 900 watts to 1400
watts.
These power ratings are usually nominal ratings, so that the actual maximum
wattage
output of a heating element at a given point in time will be within some
predetermined range of the stated value. The actual power output of a heating
element may be varied in a controlled manner, from 0 watts to the maximum
wattage
output of the heating element, by varying the voltage applied to the heating
element.
Using a higher rated heating element operated at full wattage may permit a
larger
heating reservoir to be used, while still obtaining satisfactory results in
start-up time
and temperature control.
Thus, it has been found convenient to consider a "watt density" characteristic
of a
heater. The watt density of a heater is defmed as the ratio between the total
average
power output of the heating element or elements during a brewing operation
(expressed in or converted to watts) and the volume capacity of the heating
reservoir
(expressed in or converted to milliliters). As used herein, "volume capacity"
means
the volume available within a heating reservoir to store a liquid, excluding
space in
the reservoir taken up by components such as heating elements, temperature
sensors,
and the like. Table 1 below illustrates watt density values for a range of
average
heating element power values and heater reservoir capacities typically seen in
coffee
brewers:
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
Table 1. Watt Density (watts / ml)
Average Heating Element Power (watts)
900 1000 1100 1200 1300 1400
10 90.0 100.0 110.0 120.0 130.0 140.0
15 60.0 66.7 73.3 80.0 86.7 93.3
45.0 50.0 55.0 60.0 65.0 70.0
36.0 40.0 44.0 48.0 52.0 56.0
30.0 33.3 36.7 40.0 43.3 46.7
25.7 28.6 31.4 34.3 37.1 40.0
22.5 25.0 27.5 30.0 32.5 35.0
20.0 22.2 24.4 26.7 28.9 31.1
18.0 20.0 22.0 24.0 26.0 28.0
16.4 18.2 20.0 21.8 23.6 25.5
15.0 16.7 18.3 20.0 21.7 23.3
13.8 15.4 16.9 18.5 20.0 21.5
12.9 14.3 15.7 17.1 18.6 20.0
12.0 13.3 14.7 16.0 17.3 18.7
11.3 12.5 13.8 15.0 16.3 17.5
10.6 11.8 12.9 14.1 15.3 16.5
10.0 11.1 12.2 13.3 14.4 15.6
9.5 10.5 11.6 12.6 13.7 14.7
100 9.0 10.0 11.0 12.0 13.0 14.0
105 8.6 9.5 10.5 11.4 12.4 13.3
,h 110 8.2 9.1 10.0 10.9 11.8 12.7
115 7.8 8.7 9.6 10.4 11.3 12.2
120 7.5 8.3 9.2 10.0 10.8 11.7
9 125 7.2 8.0 8.8 9.6 10.4 11.2
,a 130 6.9 7.7 8.5 9.2 10.0 10.8
135 6.7 7.4 8.1 8.9 9.6 10.4
140 6.4 7.1 7.9 8.6 9.3 10.0
145 6.2 6.9 7.6 8.3 9.0 9.7
150 6.0 6.7 7.3 8.0 8.7 9.3
155 5.8 6.5 7.1 7.7 8.4 9.0
160 5.6 6.3 6.9 7.5 8.1 8.8
165 5.5 6.1 6.7 7.3 7.9 8.5
170 5.3 5.9 6.5 7.1 7.6 8.2
175 5.1 5.7 6.3 6.9 7.4 8.0
180 5.0 5.6 6.1 6.7 7.2 7.8
185 4.9 5.4 5.9 6.5 7.0 7.6
190 4.7 5.3 5.8 6.3 6.8 7.4
195 4.6 5.1 5.6 6.2 6.7 7.2
200 4.5 5.0 5.5 6.0 6.5 7.0
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
16
250 3.6 4.0 4.4 4.8 5.2 5.6
300 3.0 3.3 3.7 4.0 4.3 4.7
350 2.6 2.9 3.1 3.4 3.7 4.0
400 2.3 2.5 2.8 3.0 3.3 3.5
450 2.0 2.2 2.4 2.7 2.9 3.1
500 1.8 2.0 2.2 2.4 2.6 2.8
550 1.6 1.8 2.0 2.2 2.4 2.5
Figure 8 illustrates a plot to show how the watt density varies with heater
reservoir
volume capacity for a given average heating element power, for example 900 or
1400
watts. As a representative example, Figure 8 shows that for a heating element
with an
average power of 1400 watts during a brewing operation used in conjunction
with a
heater reservoir having a 100 ml volume capacity, the watt density is 14 watts
/ ml.
It is preferred to have a heater with a watt density of no less than about 6
watts / ml,
more preferred to have a heater with a watt density of no less than about 9
watts / ml,
and most preferred to have a heater with a watt density of no less than about
12 watts /
ml. It is preferred to have a heater with a watt density of no more than about
30 watts
/ ml, more preferred to have a heater with a watt density of no more than
about 22
watts / ml, and most preferred to have a heater with a watt density of no more
than
about 16 watts / ml. In addition, a specific watt density of about 14 watts /
ml has
proven to be a good design. Various combinations of these preferred values may
be
made to generate different ranges of advantageous values for the watt density.
Alternatively or additionally in consideration of a watt density, it has also
been found
convenient to consider a residence-to-lag time ratio. The residence time
numerator of
this ratio is the average residence time of the brewing liquid within the
heating
reservoir. Assuming a hydrostatically full system, where there are no
significant air
pockets in the brewing liquid, the residence time numerator may be
approximated by
dividing the average flow rate of the brewing liquid into the volume capacity
of the
heating reservoir. The lag time denominator of this ratio is the amount of
time it takes
for the temperature sensor, upon the brewing liquid changing from an old
temperature
to a new temperature, to reflect 97% of the expected change in temperature.
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
17
The lag time denominator may be empirically determined for a given temperature
sensor. For example, a first pool of liquid may be kept at a first known
temperature
such as 25 Celsius, and a second pool of liquid may be kept at a second known
temperature such as 100 Celsius. A temperature sensor to be tested is placed
in the
first pool until it reflects the first temperature. The temperature sensor is
then placed
in the second pool The expected change in temperature is calculated from the
difference between the first and second temperatures, which in this example is
75
Celsius. Ninety-seven percent of that expected change is about 73 Celsius.
Thus the
lag time denominator is the time it takes the temperature sensor to reach 98
Celsius
after it is placed in the second pool (the starting temperature of 25 plus a
73
increase). Use of two pools of liquid in this manner is only one method of
measuring
the lag time denominator of the residence-to-lag ratio; others will be readily
apparent
to one of ordinary skill in the art.
As an example, if the average flow rate of the brewing liquid is 5 ml per
second, and
the volume capacity of the heating reservoir is 100 ml, then the average
residence
time of brewing liquid in the reservoir is 20 seconds. If the lag time of the
temperature sensor is then 5 seconds, the residence-to-lag time ratio is 4.
Physically,
this means the brewing liquid spends about four times as long in the heating
reservoir
getting warmed up than it takes for the temperature sensor to measure the
temperature
of the brewing liquid.
If the residence-to-lag time ratio is very small, the brewing liquid is
flowing too fast
for the temperature sensor to keep up with brewing liquid temperature changes.
This
typically occurs in small volume capacity heating reservoirs. If the residence-
to-lag
time ratio is very large, the brewing liquid temperature changes slowly enough
for the
temperature sensor to keep up. However, this can concomitantly result in long
start-
up times before brewing can begin. This latter situation typically occurs in
large
volume capacity heating reservoirs.
Therefore, it is preferred to have a residence-to-lag time ratio of no less
than about 2,
more preferred to have a residence-to-lag time ratio of no less than about 3,
and most
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
18
preferred to have a residence-to-lag time ratio of no less than about 4. It is
preferred
to have a residence-to-lag time ratio of no more than about 10, more preferred
to have
a residence-to-lag time ratio of no more than about 8, and most preferred to
have a
residence-to-lag time ratio of no more than about 6. A residence-to-lag time
ratio of
no more than about 4 has been found to be advantageous. Various combinations
of
these preferred values may be made to generate ranges of advantageous values
for the
residence-to-lag time ratio.
Figure 9 shows a supply of brewing liquid 158 held within the heating
reservoir 142
of the heater body 140. In this particular embodiment, the outlet 146 is
disposed in
the top end wall 160 of the heater body 140. Although not illustrated, the
outlet 146
may alternatively be disposed in the sidewall 162 of the heater body 140, near
the top
end wall 160. In such configurations, the outlet 146 will be advantageously
disposed
above the surface level 164 of the brewing liquid 158 during at least some
portion of a
steam purging process, as discussed further below.
Figures 10-12 show how a temperature control logic 300 may be used during a
brewing operation in a brewing device 100. In the flowcharts of these Figures,
the
rectangular elements denote processing blocks and represent software
instructions or
groups of instructions. The quadrilateral elements denote data input/output
processing blocks and represent software instructions or groups of
instructions
directed to the input or reading of data or the output or sending of data. The
flow
diagrams shown and described herein do not depict syntax of any particular
programming language. Rather, the flow diagrams illustrate the functional
information one skilled in the art may use to fabricate circuits or to
generate software
to perform the processing of the system. It should be noted that many routine
program elements, such as initialization of loops and variables and the use of
temporary variables are not shown. Prior to discussing the temperature control
logic
300, a review of the definitions of some exemplary terms used throughout the
disclosure is appropriate. Both singular and plural forms of all terms fall
within each
meaning.
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
19
"Logic," as used herein, includes but is not limited to hardware, finnware,
software
and/or combinations of each to perform a function(s) or an action(s), and/or
to cause a
function or action from another component. For example, based on a desired
application or need, logic may include a software controlled microprocessor,
discrete
logic such as an application specific integrated circuit (ASIC), or other
programmed
logic device. Logic may also be fully embodied as software.
"Software," as used herein, includes but is not limited to one or more
computer
readable and/or executable instructions that cause a computer or other
electronic
device to perform functions, actions, and/or behave in a desired manner. The
instructions may be embodied in various forms sitch as routines, algorithms,
modules
or programs including separate applications or code from dynamically linked
libraries. Software may also be implemented in various forms such as a stand-
alone
program, a function call, a servlet, an applet, instructions stored in a
memory, part of
an operating system or other type of executable instructions. It will be
appreciated by
one of ordinary skill in the art that the form of software is dependent on,
for example,
requirements of a desired application, the environment it runs on, and/or the
desires of
a designer/programmer or the like.
Turning now to the diagram of Figure 10, one embodiment of a brewing system
200
incorporating a temperature control logic 204 is shown. The system has a
controller
202 with control logic 204, in addition to the components from Figure 1 as
shown.
The controller 202 is preferably processor-based and can include various
input/output
circuitry including analog-to-digital (A/D) inputs and digital-to-analog (D/A)
outputs.
The controller 202 receives data from several sources. The flow meter 102
provides
flow data 206 indicative of the flow rate of brewing liquid from the storage
reservoir
101 to the pump 104. A heater temperature sensor 208 provides temperature data
210
indicative of the temperature of brewing liquid stored in or flowing through
the heater
106. The fluid flow path temperature sensor 110 provides temperature data 212
indicative of the temperature of brewing liquid in the fluid flow path 111
between the
heater 106 and the brewing chamber 108. As described further below, the
controller
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
202 uses this data to control 214 the brewing liquid flow rate and, if
necessary, vary
216 the power of the heating element 148 in the heater 106.
A representative temperature control logic 300 for a brewing operation is
shown in
Figure 11A and 11B. As a first step 302, the user begins the brewing operation
by
loading an amount of brewing material into the brewing chamber of a brewing
unit 14
and closing the closure mechanism 18. The user then presses the appropriate
button(s) 304 to instruct the controller 202 as to what kind of brewing
operation is
desired. This information might include the amount of brewed beverage desired
(7
ounces, 9 ounces, 14 ounces, etc.) and what kind of material is being brewed
(plain
coffee, coffee with cream, etc.). From this data, the controller 202
determines various
control parameters such as the appropriate amount of brewing liquid to supply
to the
brewing chamber, and a target temperature for the brewing liquid exiting the
heater
106. The controller 202 may also rely on the heater temperature data 210 to
set these
control parameters - for example, if the brewing liquid in the heater 106 is
relatively
cold because a brewing operation has not been recently performed, the target
temperature may be set higher.
The controller 202 then verifies 306 whether the closure mechanism 18 is shut
and
locked. The controller 202 may do this by, for example, determining whether a
limit
switch disposed proximate to the closure mechanism 18 has been tripped. If it
appears the closure mechanism 18 is not closed, the controller 202 prevents a
brew
from starting 308 and indicates to the user a problem has occurred 310. Such a
problem signal could include a stop light, a buzzer, or a similar signal. The
user then
corrects the problem 312 and presses the desired brew buttons 304 to start the
process
300 over again.
Once the closure mechanism 18 is closed, the controller 202 begins the brew
process
and indicates to the user the process has begun 314. A voltage is applied to
the
heating element 148 in the heater 106 to start heating up the brewing liquid
left over
in the heater 106 from the last brew. The power of the heater is initially set
to its
maximum rated value. From the heater temperature data 210 the controller 202
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
21
determines 316 whether the brewing liquid in the heater 106 has a sufficient
minimum
temperature T,,,u, to start a brewing process. T,,,;t, is set at the minimum
temperature
for effective brewing of a good beverage. If the temperature of the brewing
liquid in
the heater 106 is less than Tm;,,, the controller waits 318 until T,,,ffi is
reached as a
result of the liquid being heated by the heating element 148.
Once the brewing liquid in the heater 106 reaches Tm;r,, the controller 202
starts 320
the pump 104 to begin pumping brewing liquid to the brewing chamber 108. The
controller 202 checks 322 the flow meter data 206 to make sure the flow is
greater
than zero. If the controller 202 determines there is no flow, the controller
202
deactivates 324 the pump 104 and heater 106, and notifies 326 the user a
problem has
occurred. The user corrects the problem 312, such as by adding brewing liquid
to the
brewing reservoir 101, and presses the desired brew buttons 304 to start the
process
300 over again.
If the controller 202 determines the flow is greater than zero at step 322, it
next
checks 328 the temperature of the brewing liquid in the heater 210 to
determine
whether it exceeds some maximum temperature T,Y,a,t. T,,,a.' might be set, for
example,
as a maximum temperature of brewing liquid which leads to a satisfactory
brewed
beverage. If the maximum temperature is exceeded, the controller 202
deactivates
324 the pump 104 and heater 106, and notifies 326 the user a problem has
occurred.
The user corrects the problem 312, such as by adding brewing liquid to the
storage
reservoir 101, and presses the desired brew buttons 304 to start the process
300 over
again.
If the check 328 indicates the temperature of the brewing liquid in the heater
310 does
not exceed the maximum temperature TmaX, the controller checks 330 the data
212 for
temperature of the brewing liquid in the fluid flow path 111. If that
temperature 212
differs from the target temperature for the type of brew selected by the user
304, the
controller 202 follows a primary / secondary control process to vary the
temperature.
As a primary control, the controller 202 adjusts the flow rate of the brewing
liquid by
adjusting the brewing liquid flow rate, thereby controlling the temperature of
the
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
22
brewing liquid in line 111. It may do this by applying, for example, a
proportional
control, a proportional derivative control, a proportional integral control, a
proportional integral derivative control, or similar control loop. If the
brewing liquid
temperature 212 is too low, the speed of pump 104 is decreased, so that
brewing
liquid spends more time in heater 106 and thus reaches a higher temperature in
the
line 111. If the brewing liquid temperature 212 is too high, the speed of pump
104 is
increased, so that brewing liquid spends less time in heater 106 and thus does
not
reach as high a temperature in the line 111. Pump adjustments may be made in a
step-
wise fashion as the process 300 continually loops back through the checking
step 330
until the volume target is met 332. If the error between target temperature
and
measured temperature is relatively large, then the pump speed may be changed
by a
relatively large amount. If the error between target temperature and measured
temperature is relatively small, then the pump speed may be changed by a
relatively
small amount. Mechanisms other than pump speed can be used to vary the brewing
liquid flow rate, such as for example a variable size orifice disposed
downstream of
the pump.
A secondary control is provided, relying on the heating element 148 in the
event the
primary flow rate control is not sufficient. More particularly, if the flow
rate has
reached the maximum pumping capability of the particular pump being utilized,
and
the brewing liquid temperature still needs to be decreased, the controller 202
reduces
the power of the heating element 148 in the heater 106. Similarly, if the flow
rate has
reached the minimum pumping capability of the particular pump being utilized,
and
the brewing liquid temperature still needs to be increased, the controller 202
increases
the power of the heating element 148 in the heater 106. Varying the flow rate
is used
as the primary control because the flow rate can be controlled in a much more
precise
and responsive manner than the power of the heating element 148. Thus, in the
usual
operation of the temperature control process 300, the power of the heating
element
148 is usually not changed much, if at all. Rather, it usually stays at a
relatively high
level, with changes in the brewing liquid flow rate controlling the brewing
liquid
temperature. But of course, heating element power may alternatively be used as
the
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
23
sole temperature control, or the primary temperature control in conjunction
with other
controls.
After adjusting the temperature of brewing liquid 330, the controller 202
checks 332
the volume of brewing liquid which has been pumped during the brewing process.
The controller 202 can determine the amount of brewing liquid which has been
pumped by tracking the flow meter data 206 throughout the process 300, and
integrating the flow over time. For example, if a pulse meter is used, the
controller
can count the number of pulses and determine volume from the known volume of
brewing liquid pumped per pulse. If the target volume for the brew selected by
the
user has not been met, the pumping continues 334 and the process 300 loops
back to
the check flow meter step 322. If the target volume has been met, the
controller 202
either shuts down the system or, if desired, begins a purging process.
One example of a purging process is shown in Figure 12. At the beginning of
this
purging process 400, the pump 104 is turned off but the heater 106 is left on
402. The
heating element power is set at its maximum power rating 404, if it is not
already at
that level. The temperature of the brewing liquid in the heater 210 is
monitored 406
to determine when it reaches the boiling point for the brewing liquid, which
is 100
Celsius for water. This causes steam to rise up from the brewing liquid which
is lying
dormant in the heater 106 as a result of the pump 104 being turned off. The
steam
permeates through the fluid flow path 111 to reach the brewing chamber in the
brewing unit 14. There the steam dries the now-used brewing material to an
extent
that it is easily removed by the user without excessive sticking, dripping or
other
mess. In the event a combined coffee / cream pod was used, the steam
additionally
operates to force excess cream or other liquid out of the pod.
The heater shown in Figure 9 and described above is particularly useful in
connection
with a steam purging process. Steam rising from the surface 164 will tend to
cany at
least some excess, unvaporized brewing liquid along with it. With the outlet
146 of
the heater 106 disposed above the surface level 164 of the brewing liquid,
however,
large amounts of excess brewing liquid are unlikely to reach the outlet 146.
That is
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
24
because gravity tends to cause most of the brewing liquid carried with the
steam to
fall back into the pool 158 before the steam reaches the outlet 146. -
At the beginning of the purging process, the brewing liquid surface level 164
may be
disposed at or near the level of the outlet 146. In that event, for some
amount of time,
relatively large amounts of excess unvaporized brewing liquid may remain
trapped in
the flow of steam as it exits the heating reservoir 142. However, as that
trapped liquid
is carried away and other liquid is converted to steam, the surface level 164
falls. At
some point after steam begins generating, the surface level 164 reaches a low
enough
level in the heating reservoir 142 that most of the liquid carried in the
steam falls back
into the pool 158 before the steam reaches the outlet 146. This makes for
improved
reproducibility from brew to brew of liquid volume output during the purging
process.
Once the brewing liquid boiling point temperature is reached, a purging timer
401 is
started 408. The purging timer 401 may, for example, be incorporated as part
of the
controller 202 as shown in Figure 10. Steam is then generated for a pre-
determined
amount of time, as measured by the purging timer 401. The steam time is set at
a pre-
determined amount which is effective to purge the system by sufficiently
reducing the
amount of liquid left behind, including liquid left in the brewing chamber.
The
purged liquid is forced through the brewing chamber and out the spout 20 of
the
brewing unit 14. Thus, the purging process 400 will cause some amount of
brewed
beverage to be dispensed after a brewing operation 300 is complete. However,
the
amount of brewed beverage generated during the purging process 400 is highly
repeatable from brew to brew, because steam is generated for a set amount of
time
and in a controlled fashion. Once this repeatable amount of dispensed beverage
is
empirically determined for a particular brewer device, the target volume value
used in
step 332 of the brewing operation 300 may be reduced so that the overall
amount of
brewed beverage produced as a result of both processes 300, 400 is highly
repeatable
from brew to brew.
For generating one or two cups of black coffee, it is advantageous to have a
steam
time of no less than about 5 seconds, or no less than about 7 seconds, or no
less than
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
about 9 seconds. For generating one or two cups of a combination of coffee and
cream brewed together in the brewing chamber, it is advantageous to have a
steam
time of no less than about 10 seconds, or no less than about 12 seconds, or no
less
than about 14 seconds.
For generating one or two cups of black coffee, it is advantageous to have a
steam
time of no more than about 15 seconds, or no more than about 13 seconds, or no
more
than about 11 seconds. For generating one or two cups of a combination of
coffee
and cream brewed together in the brewing chamber, it is advantageous to have a
steam time of no more than about 20 seconds, or no more than about 18 seconds,
or
no more than about 16 seconds.
Instead of starting the purging timer 401 (Figure 10) when the brewing liquid
in the
heater 106 reaches its boiling point 408, the timer 401 may alternatively be
started
earlier in the process. For example, it may be started when the pump 104 is
shut off
402, or the heating element power is set to maximum 404.
Once the brewing liquid boiling point temperature is reached, it may be
advantageous
to reduce the power of the heating element 410 for the remainder of the steam
generation process. For example, the heating element power may be reduced by
as
much as 50 percent of the power needed to heat the brewing liquid during the
brewing
operation. This helps prevent generating too much steam, which can result in
splashing of the hot brewed beverage as it is dispensed into a cup for
consumption, as
well as over-pressurizing the system.
Once the set time period has elapsed, or the purging process otherwise ended,
the
heater 106 is turned off 412. As discussed above, a vacuum vent valve 112 may
be
disposed within the fluid flow path 111 to relieve a vacuum occurring in the
fluid
flow path 111 as a result of steam condensation forming in the path 111 after
the
heater 106 is turned off. It may also be advantageous to turn the pump 104 on
414 to
refill the heater 206 at this point in the process 400. This would replace
brewing
liquid lost during the steam generation process, and ensure a sufficient
amount of
brewing liquid is in the heater 106 when the brewing process begins again. The
user
CA 02617885 2008-01-31
WO 2007/022388 PCT/US2006/032198
26
is notified that the brew process is complete 416. It may be advantageous to
provide a
delay between the time the heater 106 is turned off 412 and the time of user
notification 416. Such a delay would permit the steam remaining in the system
to
further dry the brewing material and filter paper in the brewing chamber, and
to allow
the system to depressurize.
While the present invention has been illustrated by the description of
embodiments
thereof, and while the embodiments have been described in considerable detail,
it is
not intended for this to restrict or in any way limit the scope of the claimed
invention
to such detail. Additional advantages and modifications will readily appear to
those
skilled in the art. For example, although the steps of the temperature control
process
300 and the purging process 200 have been described in some detail and in a
particular order, of course different or additional steps may be used, or the
described
steps performed in a different order. Therefore, the invention in its broader
aspects is
not limited to the specific details and illustrative examples shown and
described.
Accordingly, departures may be made from such details without departing from
the
spirit or scope of the general inventive concept.
