U.S. patent number RE37,173 [Application Number 09/401,718] was granted by the patent office on 2001-05-15 for coffee and tea brewing apparatus and system.
This patent grant is currently assigned to Harry D. Jefferson, Jr.. Invention is credited to Harry D. Jefferson, Jr., Dale W. Ploeger.
United States Patent |
RE37,173 |
Jefferson, Jr. , et
al. |
May 15, 2001 |
Coffee and tea brewing apparatus and system
Abstract
A method and system for brewing a desired volume of coffee at a
selected brew time, in which a volume of water corresponding to the
desired volume of coffee is heated and directed into contact with
coffee grounds in a brewing chamber. Contact between at least a
portion of the heated water and the coffee grounds is maintained
for approximately the selected brew time to form brewed coffee. The
brewing time, however, is substantially independent of the desired
volume of coffee to be brewed and is controlled by control of the
rate at which heated liquid flows into or out of the brewing
chamber. At the expiration of the brewing time, brewed coffee is
released through an opening in the brewing chamber and into an
underlying receptacle.
Inventors: |
Jefferson, Jr.; Harry D.
(Honolulu, HI), Ploeger; Dale W. (Menlo Park, CA) |
Assignee: |
Jefferson, Jr.; Harry D.
(N/A)
|
Family
ID: |
24007377 |
Appl.
No.: |
09/401,718 |
Filed: |
September 23, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
504701 |
Jul 20, 1995 |
05669287 |
Sep 23, 1997 |
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Current U.S.
Class: |
99/299; 99/283;
99/295; 99/302R; 99/304 |
Current CPC
Class: |
A23F
5/26 (20130101); A23F 5/262 (20130101); A47J
31/002 (20130101); A47J 31/0621 (20130101) |
Current International
Class: |
A47J
31/06 (20060101); A47J 31/00 (20060101); A47J
037/00 () |
Field of
Search: |
;99/299,283,307,295,32R,304,275,279 ;426/433 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2839295 |
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Mar 1980 |
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DE |
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0234790 |
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Apr 1986 |
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DE |
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3935384 |
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May 1991 |
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DE |
|
0019291 |
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Nov 1980 |
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EP |
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2260891 |
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May 1993 |
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GB |
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Other References
"Brewed Coffee" Consumer Reports, Oct. 1994, pp. 640-653..
|
Primary Examiner: Alexander; Reginald L.
Attorney, Agent or Firm: Sonnenschein Nath &
Rosenthal
Claims
We claim:
1. Apparatus for brewing a desired volume of coffee comprising:
(a) a receptacle for receiving brewed coffee;
(b) a brewing chamber including a filter within the brewing chamber
for holding coffee grounds;
(b) means for selecting a volume of water corresponding to the
desired volume of coffee to be brewed;
(d) means for heating the water to brewing temperature and
directing the heated water into the brewing chamber for contact
with the coffee grounds in the filter basket;
(e) means for maintaining contact between at least a portion of the
heated water and the coffee grounds for a period of time which is
substantially independent of the selected volume of coffee to be
brewed; and
(f) means for transferring the brewed coffee into the
receptacle.
2. The apparatus of claim 1 having a reservoir for containing the
selected volume of water prior to brewing with both the brewing
chamber and the receptacle being larger in volume than the
reservoir.
3. The apparatus of claim 2 in which the means for heating the
selected volume of water comprises means for heating the water
substantially to brewing temperature in the reservoir prior to
commencing transfer of the water to the brewing chamber.
4. The apparatus of claim 1 which a screen is mounted in the
brewing chamber between the reservoir and the filter to intercept
coffee grounds before the grounds reach the filter to increase the
coffee flow rate through the filter..Iadd.
5. Apparatus for brewing a desired volume of tea comprising:
(a) a receptacle for receiving brewed tea;
(b) a brewing chamber including a filter within the brewing chamber
for holding tea leaves;
(c) means for selecting a volume of water corresponding to the
desired volume of tea to be brewed;
(d) means for heating the water to brewing temperature and
directing the heated water into the brewing chamber for contact
with the tea leaves in the filter;
(e) means for maintaining contact between at least a portion of the
heated water and the tea leaves for a period of time which is
substantially independent of the selected volume of tea to be
brewed; and
(f) means for transferring the brewed tea into the receptacle.
.Iaddend..Iadd.
6. The apparatus of claim 5 having a reservoir for containing the
selected volume of water prior to brewing with both the brewing
chamber and the receptacle being larger in volume than the
reservoir. .Iaddend..Iadd.
7. The apparatus of claim 6 in which the means for heating the
selected volume of water comprises means for heating the water
substantially to brewing temperature in the reservoir prior to
commencing transfer of the water to the brewing chamber.
.Iaddend..Iadd.
8. The apparatus of claim 5 in which a screen is mounted in the
brewing chamber between the reservoir and the filter to intercept
tea leaves before the leaves reach the filter to increase the tea
flow rate through the filter. .Iaddend..Iadd.
9. Apparatus for brewing a desired volume of a beverage brewed from
water and biological substances selected from the group comprising
coffee ground elements and tea leaf elements comprising:
a receptacle for receiving said brewed beverage;
a brewing chamber including a filter within the brewing chamber for
holding said biological substances;
means to select a volume of water corresponding to the desired
volume of beverage to be brewed;
a heater to heat the selected volume of water to brewing
temperature and directing the heated selected volume of water into
the brewing chamber for contact with the biological substances in
the filter;
means for at least a portion of said selected volume of heated
water being maintained in contact with said biological substances
for a period of time which is substantially independent of the
selected volume of beverage to be brewed; and
an opening to transfer the brewed beverage into the receptacle.
.Iaddend..Iadd.
10. The apparatus of claim 9 including a reservoir for containing
the selected volume of water prior to brewing with both the brewing
chamber and the receptacle being larger in volume than the
reservoir. .Iaddend..Iadd.
11. The apparatus of claim 10 in which the heater for heating the
selected volume of water heats the water substantially to brewing
temperature in the reservoir prior to commencing transfer of the
water to the brewing chamber. .Iaddend..Iadd.
12. The apparatus of claim 9 in which a screen is mounted in the
brewing chamber between the reservoir and the filter to intercept
biological substances before the biological substances reach the
filter to increase the beverage flow rate through the filter.
.Iaddend..Iadd.
13. Apparatus for brewing a desired volume of brewed beverage made
from biological substances selected from the group consisting of
coffee grounds and tea leaves, comprising:
a receptacle for receiving said brewed beverage;
a brewing chamber including a filter within the brewing chamber for
holding said biological substances;
means for selecting a volume of water corresponding to the desired
volume of beverage to be brewed;
a heated to heat the water to brewing temperature and automatically
directing the heated water into the brewing chamber for contact
with the biological substances in the filter;
means for at least a portion of heated water and the biological
substances maintaining in contact for a period of time which is
substantially independent of the selected volume of beverage to be
brewed; and
means for automatically transferring the brewed beverage into the
receptacle. .Iaddend..Iadd.
14. The apparatus of claim 13 having a reservoir to contain the
select volume of water prior to brewing with both the brewing
chamber and the receptacle being larger in volume than the
reservoir. .Iaddend..Iadd.
15. The apparatus of claim 14 in which the heater for heating the
selected volume of water heats the water substantially to brewing
temperature in the reservoir prior to commencing transfer of the
water to the brewing chamber. .Iaddend..Iadd.
16. The apparatus of claim 13 in which a screen is mounted in the
brewing chamber between the reservoir and the filter to intercept
the biological substances before the biological substances reach
the filter to increase the beverage flow rate through the filter.
.Iaddend..Iadd.
17. An apparatus for brewing a desired volume of brewed beverage
made from biological substances selected from the group consisting
of coffee grounds and tea leaves, comprising:
a brewing chamber having a capacity at least equal to said desired
volume;
a receptacle for receiving brewed beverage having a capacity at
least equal to said desired volume;
a flow control valve between said brewing chamber and said
receptacle, whereby said flow control valve adjustably controls the
flow of brewed beverage from said brewing chamber into said
receptacle; and
a screen removably mounted in said brewing chamber for holding said
biological substances, whereby water introduced into said brewing
chamber forms a slurry with said biological substances, whereby a
screened portion of said biological substances is screened by said
screen and thereby prevents said biological substances from being
more flow restrictive than said flow control valve.
.Iaddend..Iadd.
18. An apparatus according to claim 17, further comprising:
a filter holder holding a filter mounted between brewing chamber
and said receptacle. .Iaddend..Iadd.
19. An apparatus according to claim 18, further comprising:
a housing;
a vessel having a capacity at least equal to said desired volume
mounted in said housing;
a heater operatively connected to said vessel, whereby said heater
can heat water in said vessel to a brewing temperature; and
a pump operably connected between said vessel and said brewing
chamber to pump water heated to said brewing temperature into said
brewing chamber;
said brewing chamber being mounted in said housing.
.Iaddend..Iadd.
20. An apparatus according to claim 19, wherein said pump comprises
a discharge tube extending between said vessel and said brewing
chamber, whereby water heated in said vessel to a brewing
temperature is forced through said discharge tube into said brewing
chamber. .Iaddend..Iadd.
21. An apparatus according to claim 19, wherein said pump forces
said water into said brewing chamber in chamber in approximately 30
seconds. .Iaddend..Iadd.
22. An apparatus according to claim 19, further comprising:
a thermostat operatively connected to said vessel to maintain said
water at said brewing temperature in said vessel.
.Iaddend..Iadd.
23. An apparatus according to claim 22, wherein said thermostat
maintains said water at a brewing temperature when said water is
pumped into said brewing chamber of between approximately 185
degrees Fahrenheit and approximately 212 degrees Fahrenheit.
.Iaddend..Iadd.
24. An apparatus for brewing a desired volume of brewed beverage
made from biological substances selected from the group consisting
of coffee grounds and tea leaves, comprising:
a brewing chamber having a capacity at least equal to said desired
volume;
a receptacle for receiving brewed beverage having a capacity at
least equal to said desired volume;
a flow control valve between said brewing chamber and said
receptacle, whereby said flow control valve adjustably controls the
flow of brewed beverage from said brewing chamber into said
receptacle;
a filter holding means for holding a filter mounted in said brewing
chamber; and
a weir detachably mounted above said filter holder means for
capturing biological substances, whereby water introduced into said
brewing chamber forms a slurry with said biological substances,
whereby a settled portion of said biological substances settles on
said weir and thereby prevents biological substances filtered by
said filter from being more flow restrictive than said flow control
valve. .Iaddend..Iadd.
25. An apparatus according to claim 24, further comprising:
a housing;
a vessel having a capacity at least equal to said desired volume
mounted in said housing;
a heater operatively connected to said vessel, said heater adapted
to heat water in said vessel to a brewing temperature; and
a pump operably connected between said vessel and said brewing
chamber to pump water heated to said brewing temperature into said
brewing chamber, wherein said brewing chamber is mounted in said
housing. .Iaddend..Iadd.
26. An apparatus for brewing a desired volume of brewed beverage
made from biological substances selected from the group comprising
coffee grounds and tea leaves, comprising:
a housing;
a vessel having a capacity at least equal to said desired volume
mounted in said housing;
a heater operatively connected to said vessel, said heater adapted
to heat water in said vessel to a brewing temperature;
a brewing chamber mounted in said housing;
a pump operably connected between said vessel and said brewing
chamber;
a receptacle for receiving brewed beverage having a capacity at
least equal to said desired volume;
a flow control valve between said vessel and said brewing chamber,
whereby said flow control valve adjustably controls the flow of
heated water from said vessel into said brewing chamber;
a filter holder means for holding a filter mounted between said
vessel and said brewing chamber;
a screen mounted above said filter holder means, whereby water
introduced into said brewing chamber forms a slurry with said
biological substances, whereby a screened portion of said
biological substances is screened by said screen and thereby
prevents biological substances filtered by said filter from being
more flow restrictive than said flow control valve; and
a body having a large discharge opening in fluid communication with
said brewing chamber, whereby brewed beverage can quickly drain
from said brewing chamber so as not to extend brew time.
.Iaddend..Iadd.
27. An apparatus according to claim 26, further comprising:
a valve door controllably closing said brewing chamber; and
a timer cooperatively connected to said valve door to automatically
release brewed beverage from said brewing chamber into said
receptacle after said brew time. .Iaddend..Iadd.
28. An apparatus according to claim 19, wherein said pump
comprises:
a lid sealing said vessel;
a fill tube having a vent hole extending through said lid; and
a discharge tube extending between said vessel and said brewing
chamber; whereby heating said water in said vessel causes steam to
form in said vessel, and said steam increases pressure in said
vessel to force heated water out of said vessel and into said
brewing chamber, and a portion of said steam escapes through said
vent hole. .Iaddend..Iadd.
29. An apparatus according to claim 28, wherein said vent hole has
a diameter of approximately 0.03 inches. .Iaddend..Iadd.
30. An apparatus according to claim 17, wherein said flow control
valve is controllable to allow said desired volume of beverage to
flow into said receptacle after a brew time of between
approximately 30 seconds and approximately 4 minutes.
.Iaddend..Iadd.
31. An apparatus according to claim 17, wherein said flow control
valve comprises:
a pair of nested cones, each cone having an aperture, said cones
being rotatable with respect to each other, whereby rotating said
cones causes said apertures to overlap and increase or decrease the
rate at which liquid flows out of said brewing chamber. .Iaddend.
Description
FIELD OF THE INVENTION
The present invention relates generally to the field of cooking
appliances and particularly to the field of apparatuses and systems
for brewing coffee and tea.
BACKGROUND OF THE INVENTION
Coffee is brewed by placing hot water into contact with ground,
roasted coffee for a given period of time. Coffee beans contain
approximately 600 chemical compounds, a high percentage of which
result in bitter and poor tasting coffee, which is often
incorrectly referred to as "strong coffee." These undesirable
compounds are normally released into brewed coffee when the hot
water remains in contact with the ground coffee beans for
relatively long durations. A primary influence on the taste of
brewed coffee is therefore the "brew time," the amount of time that
the heated water is in contact with the ground coffee beans. Brew
time is similarly important to the brewing of teas.
Experts in the coffee industry recommend brewing so-called "regular
grind" coffee using brew times within the range of two to four
minutes, where the brew time is the amount of time for which heated
liquid is in contact with the ground beans. For free grinds (often
called "espresso grinds"), brew times of approximately 20 to 30
seconds are recommended. It is also recommended that water which
has been heated to approximately 205.degree. F. be used for brewing
coffee.
In a typical coffee maker available for commercial and consumer
use, coffee grounds are held in a paper filter which rests inside a
cone-shaped plastic or metal chamber. An aperture having fixed
dimensions is formed at the bottom of the chamber. Heated water
(which in the prior art is usually only heated to between
170.degree. and 185.degree. F.) is pumped onto the coffee grounds
in the plastic chamber at a relatively constant rate (which, as
discussed below, is too low and thus results in a brew time that is
too long). Brewed coffee flows from the brewing chamber through the
aperture, and accumulates in a receptacle positioned below the
brewing chamber. The rate at which the brewed coffee flows out of
the brewing chamber is relatively constant and is dependent upon
the diameter of the aperture and the flow restriction caused by
coffee accumulation on the filter surface.
Because this prior art coffee maker pumps heated water onto the
coffee grounds and discharges brewed coffee from the brewing
chamber at constant flow rates, the amount of time during which the
liquid is in contact with the coffee grounds is proportional to the
amount of coffee to be brewed. For example, if a large quantity of
coffee is to be brewed, the large volume of brewed coffee will take
longer to flow into and drain from the brewing chamber than would a
smaller volume. The brew time for a volume of four cups of coffee
is thus approximately one-third the time of that for twelve cups.
The prior art coffee maker therefore maintains contact between the
coffee grounds and the liquid for durations that are much longer
time than those recommended. Amongst currently available coffee
makers, these durations range from approximately eight minutes to
15 minutes for 12 cups, where a "cup" of coffee is normally
approximately 5 fluid ounces.
Prior art coffee makers utilize various mechanisms for pumping
heated water in the brewing chamber. One such prior art coffee
maker utilizes a "thermal pump" to heat water and deliver the
heated water into the brewing chamber.
To brew coffee in a thermal pump device, a user fills a reservoir
in the coffee maker with cool water. The water flows downwardly
from the reservoir through flexible tubing, then through a check
valve, and finally into a metal tube which is heated by a hot plate
that also supports a coffee pot. A vertically-oriented plastic tube
is continuous with the heated tube and has a discharge end which
extends into the brewing chamber.
When the reservoir is filled with water, both the heated tube and
the plastic tube become filled with a column of water. The user
activates a power switch to begin brewing, causing the heating tube
to heat the water inside it to the point of boiling. The boiling
water generates a steam bubble which rises and pushes the column of
water in the vertical section of tube upwardly, until the column of
water flows out the discharge end of the tube and flows over the
ground coffee. As the water exits the tube, the pressure on the
bubble is reduced. The bubble thus expands rapidly and pushes the
column of water out in a short burst. The check valve prevents the
steam bubble from pushing the water back into the reservoir.
Once the steam bubble has exited the tube, additional water enters
the tube from the reservoir and the cycle repeats. This system
produces a "pulsed" flow which has a relatively constant flow rate
averaged over the total flow time.
Another currently available coffee maker employs thermal pulse
technology in combination with a diverter valve that diverts a
portion of the heated water directly into the coffee pot below the
brewing chamber, while the remainder of the heated water is
directed into the brewing chamber. The diverted water dilutes the
brewed coffee and reduces its perceived "strength." This method,
which is sometimes referred to as the 80/20 method since
approximately 20% of the heated water is diverted, is found in
brewing systems sold for commercial use as well as those sold for
the home.
A third type of currently available coffee brewing system has a
pumping mechanism which utilizes a heated vessel similar to a
residential hot water heater. At all times, water having a
temperature of 200.degree. F. is held in the heated vessel. To brew
coffee, a user pours the appropriate mount of cool water through an
opening on the top of the machine. The cool water flows through a
tube into the heated vessel and displaces the heated water, causing
it to exit from the heated vessel via an outlet positioned over the
coffee grounds. The cool water poured into the heated vessel
subsequently becomes heated to 200.degree. F. in preparation for
the next coffee-making cycle.
The heated vessel system is advantageous over the thermal pulse
system in that the rate at which heated water flows onto the coffee
grounds in the heated vessel system is substantially higher. For
example, 10 cups of coffee are typically brewed in approximately
four minutes.
Although each of the above-described coffee brewing systems are
somewhat satisfactory for brewing small quantifies of coffee, it
has been found that the taste of coffee brewed using those systems
is inconsistent over the range of volumes of coffee that those
systems can produce. It has been discovered that coffee having
consistent flavor can be produced, regardless of the volume of
coffee being brewed at one time, if the brew time used in the
brewing process is substantially the same for any volume of coffee
being brewed in the system. Each of the prior art systems described
above lacks a feature which will maintain a consistent brew time
regardless of the quantity of coffee to be made in the system. A
new coffee making system which utilizes a consistent brew time is
therefore desirable.
SUMMARY OF THE INVENTION
The present invention is a method and system for brewing a desired
volume of coffee at a selected brew time. A volume of water
corresponding to the desired volume of coffee is heated and
directed into contact with coffee grounds in a brewing chamber.
Contact between at least a portion of the heated water and the
coffee grounds is maintained for approximately the selected brew
time to form brewed coffee. The brewing time, however, is
independent of the desired volume of coffee to be brewed. At the
expiration of the brewing time, brewed coffee is released through
an opening in the brewing chamber and into an underlying
receptacle.
The advantage of this new coffee maker is that it allows a user to
brew coffee which will be of consistent quality regardless of the
mount of coffee brewed. This is achieved by maintaining a constant
"brew time," i.e. the time the ground coffee is exposed to hot
water, regardless of the amount of coffee to be made. In the
preferred embodiment, this is achieved by quickly dispensing heated
water into a brewing chamber that contains the ground coffee. The
flow of the water out of the brewing chamber is controlled so that
the ground coffee is exposed to heated water in the brewing chamber
for the desired brewing time.
The coffee making system of the present invention provides
consistently superior tasting coffee and further allows the user to
control the brewing time to adjust the coffee taste according to
personal preference and experience and is adaptable to standard
ground coffee and fine ground espresso type grind.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a coffee maker according to the
present invention.
FIGS. 2A and 2B are a front cross-section view and a side
cross-section view, respectively, of a coffee maker according to
the present invention.
FIG. 3 is a side plan view of a brewing chamber assembly according
to the present invention.
FIGS. 4A, 4B, and 4C are side plan views of the screen assembly,
filter, and cone of the brewing chamber assembly of FIG. 3.
FIGS. 5A and 5B are schematic models of fluid flow through a prior
art coffee maker brewing assembly and through a brewing assembly
according to the present invention, respectively.
FIGS. 6A and 6B are cross-sectional side views of a second
embodiment of a brew chamber assembly according to the present
invention.
FIGS. 7A and 7B are partial cross-section views of the underside of
the preferred valve body of the coffee maker of the present
invention.
FIGS. 8A and 8B are partial cross-section views of the underside of
a second embodiment of a valve body for use with the coffee maker
of FIG. 2A, and FIG. 8C is a side view of the roller of the valve
body shown in FIGS. 8A and 8B.
FIG. 9 is a front plan view of a valve body according to the
present invention, showing the control knob and its surrounding
markings.
FIGS. 10A and 10B are partial cross-section views of the underside
of a third alternative of a valve body of the coffee maker of the
present invention.
FIGS. 11A and 11B are partial cross-section views of the underside
of a fourth embodiment of a valve body of the coffee maker of the
present invention.
FIG. 12 is a simplified schematic representation of a coffee
brewing system using the valve body of FIGS. 11A and 11B.
FIG. 13 is a simplified flow diagram illustrating operation of a
coffee brewing system using the valve body of FIGS. 11A and
11B.
FIG. 14 is a side section view of a brewing chamber assembly for a
fifth embodiment of a valve system according to the present
invention.
FIGS. 15A through 15D are a series of top section views of the
brewing chamber of FIG. 14, showing varying degrees of alignment of
the apertures of the inner and outer cones.
FIGS. 16 and 17 are side views of the brewing chamber of FIG. 14,
illustrating different markings which may be printed on the side of
the cone to facilitate user control of brew time.
FIG. 18 is a side plan view of a sixth embodiment of a valve system
according to the present invention, showing an amplifier circuit, a
timer, and an input device in simplified schematic form.
FIG. 19 is a partial cross-sectional side view of a seventh
embodiment of a coffee making system according to the present
invention, in which brew time is controlled by controlling flow
rate of water into the brewing chamber.
FIG. 20 is a side elevation view of an alternate embodiment of a
screen component, in which the screen has a convoluted surface.
DETAILED DESCRIPTION OF THE INVENTION
The present invention controls the amount of time for which heated
liquid is in contact with ground coffee in order to enable
consistent production of superior tasting coffee, regardless of the
volume of coffee to be made. Control of brew time is maintained by
controlling the rate of fluid flow at one of two points in the
brewing system: at the point where brewed coffee exits the brewing
chamber (the chamber in which the heated water and grounds are
combined) or at the point where heated water is introduced into the
brewing chamber. Examples of each type of brewing time control will
be described below. Although these examples are given with respect
to coffee, it should be understood that the invention is equally
applicable to other brewed liquids, such as teas.
Output Control
The preferred embodiment and several of the alternative embodiments
control brew time by regulating the rate of flow of brewed coffee
out of the brewing chamber.
Referring to FIG. 2A, the preferred embodiment is comprised
generally of a housing 10, a heated water vessel 32, a brewing
chamber assembly 12, a valve body 14, and a coffee receptacle 16.
Generally speaking, during operation water is heated in the vessel
32 and pumped in a continuous flow into the brewing chamber 12
where it contacts coffee grounds. A pre-determined "brew time,"
i.e. the approximate time for which heated water is in contact with
the coffee grounds, is ensured by the valve body 14 which is
adjusted to increase or decrease the rate of liquid flow from the
brewing chamber 12.
A front section view of the coffee maker according to the preferred
embodiment is shown in FIG. 2A and a side section view is shown in
FIG. 2B. As can be seen, the housing 10 includes a base wall 18, a
pair of side walls 20, 22, and a back wall 24. As shown in FIG. 1,
a front wall 26 covers one side of the housing 10. The housing 10
also has a top wall 28 which has an opening 30 on one side.
Referring again to FIGS. 2A and 2B, water to be heated for use in
the brewing process is heated in a vessel 32 which is mounted to
back wall 24 of the housing 10. The vessel preferably has a
two-liter capacity and is preferably made of stainless steel. A lid
34 for the vessel 32 is preferably sealed to a flange 36 welded to
the vessel by conventional means. An opening 38 is formed in the
lid 34 (FIG. 2B).
A fill tube 40 extends through the opening 38 in the lid 34 and
through the opening 30 in top wall 28 of the housing 10 (FIG. 1).
Fill tube 40 has a cap 42 which seals the fill tube against some
steam and/or pressure loss, although a vent 44 having a diameter of
approximately 0.030 inches is formed in the fill tube 40 just
beneath the cap 42. During use the vent 44 allows a small amount of
steam to escape from the vessel when water in the vessel is
heated.
A second hole 46 in the lid 34 of vessel 32 receives a discharge
tube 48. In the preferred embodiment, discharge tube 48 has a long
vertical portion 50 which extends downwardly through the hole 46 in
the lid 34 and which reaches to within 1/8" of the bottom of the
vessel 32. Extending approximately perpendicularly of vertical
portion 50 is substantially horizontal portion 52 which is in fluid
communication with vertical portion 50. Finally, a discharge end 54
extends downwardly from (and is in fluid communication with)
horizontal portion 52. Discharge end 54 provides an outlet through
which heated water enters the brewing chamber 12 as will be
described in detail below.
A heater 56 is attached to the exterior of vessel 32. Heater 56 is
preferably a 900 to 1200 Watt band heater which is electrically
coupled (by conventional means) via a thermostat 62 to a power
switch 58. The power switch is in turn electrically coupled in a
conventional manner to a source of power such as a battery (not
shown) or a power cord 60 which may be plugged into a wall
outlet.
Thermostat 62 is fixed to the vessel 32 just above the heater 56.
When the thermostat detects a vessel wall temperature of in excess
of 240.degree.F., it automatically switches off the power to the
heater to prevent overheating of the vessel.
The brewing chamber 12 will next be described. Referring to FIGS. 3
and 4A-4C, it can be seen that one preferred brewing chamber
assembly 12 has three general components. The first component is a
screen component 64 which includes a plastic ring 66 having upper
and lower edges 65, 67. Attached to edge 67 of the ring 66 is a
screen 68. The screen 68 is preferably formed of 20 mesh screen
using 0.010 inch diameter stainless steel wire.
A second part of the brewing chamber assembly 12 is a plastic or
metal cone 70 (FIG. 4C) which is circular in cross-section and
which has an open top 72. The bottom of the cone 70 is closed by
bottom wall 74. A tube 76 which is in fluid communication with the
interior of the cone 70 protrudes from the cone as shown in FIG.
4C. The tube 76 is preferably made of food grade silicone and has a
preferred inner diameter of 0.5 inches.
A filter 78 is disposed between the screen component 64 and the
cone 70 in the brewing chamber assembly 12. The filter 78 is
preferably a paper, nylon or gold filter of the type generally
available for use with drip coffee makers, although filters of any
of a variety of materials may be used in the system. For the
purpose of this description, the term "filter" will be used to
denote any of type of filter useful for brewing coffee and/or tea,
including those made from paper, nylon or metal. Teas having large
or whole leaves may be brewed without a filter, since such teas are
relatively free of small particles which would require removal by a
filter.
When brewing chamber assembly 12 is assembled, upper edge 80 of
filter 78 is pinched between a skirt 82 at the base of ring 66 and
the top 72 of cone 70 in order to trap and seal the edge of the
filter. This prevents the filter from collapsing or folding during
use, and prevents heated water from by-passing the filter. The
connection between ring 66 and top 72 of cone 70 should preferably
be leak-proof, since the entire brew chamber (which preferably has
a capacity of approximately 60 oz, corresponding to 12 "cups" of
coffee) may fill with heated water during use.
As described above, a beneficial way to maintain a constant brew
time is to closely control the rate at which water exits the
brewing chamber, since the more quickly water exits the brewing
chamber the shorter the brew time. The screen holder 66 and screen
68 in the brewing chamber assembly 12 facilitate control of the
rate at which water enters and exits the brewing chamber 12.
As described above, in conventional coffee makers the wet bed of
coffee grounds and the wet paper filter inside the brewing chamber
restrict flow out of the brewing chamber. The flow of the water out
of the brewing chamber can be modeled as a pipe P1 with a series of
restrictions as shown in FIG. 5A. Water flowing through the pipe
model P1 is represented by arrows labeled W1. As shown, the water
must flow through a bed of coffee grounds C1, then through the
filter F1, and finally through an orifice O1 which has a set
diameter opening and which includes a flow control valve V1 for
controlling rate of flow through the orifice O1. Since active
control of the liquid flow is most easily carried out at the flow
control valve, the flow control valve should be the most
restrictive element along the flow path of the water. However,
because of the thickness and density of the bed of coffee which is
placed inside the brewing chamber, the bed of coffee is instead the
most restrictive element in the flow path and it thus impedes the
effectiveness of the flow control valve. It is therefore desirable
to reduce the amount of flow restriction caused by the coffee bed,
so that the flow control valve will more effectively control the
flow rate of the water.
The brewing chamber design of the present invention is an effective
means for reducing the amount of restriction caused by the bed of
coffee in the brewing chamber. When coffee is loaded into the
brewing chamber, the coffee grounds are trapped by the screen 68.
As heated water quickly enters the brewing chamber, a slurry is
formed and as the water drains from the brewing chamber
approximately 70% of the grounds are trapped by the screen while
others fall through the screen and onto the filter 78. The screen
therefore prevents the bed of coffee grounds from becoming too
thick on the filter and it allows water to flow easily through the
screen and through grounds trapped on the screen. The bed of coffee
on the filter (which is thus reduced by approximately 70%) is less
restrictive than it would be without the screen and the flow rate
through this layer is thus increased. The overall restrictive
effect of the coffee grounds is less than it would be without the
screen and it leaves the flow control valve with a dominant role in
controlling the flow of water. This point is illustrated in the
"pipe model" P2 of FIG. 5B, in which flow restriction of the
brewing chamber of the present invention is modeled and in which
W2, C2, F2 and V2 designate the water flow, coffee layers, filter,
and control valve, respectively. Referring to FIG. 20, it may also
be desirable to replace screen 68 with a screen or weir 468 which
has a convoluted surface in order to increase the screen's surface
area such that the bed of coffee which forms on the screen has a
smaller thickness.
An alternative brewing chamber assembly 312 is shown in FIGS. 6A
and 6B. The brewing chamber assembly 312 includes a cone 370 and a
tube 376 extending substantially downwardly of the cone 370. A
filter 378 is positioned inside the cone 370.
Detachably mounted to the top of the cone 370 is an extension 371
which includes a pair of substantially parallel weirs 373 extending
across it. Each weir 373 has an opening 375 formed through it which
is preferably vertically aligned with the opening in the other of
the weirs 373. During use of the alternative brewing chamber 312,
the extension 371 is removed from the cone 370 and ground coffee
400 is placed in the filter 378. When heated water is pumped into
the brewing chamber (as will be described in detail below), the
coffee grounds and water form a slurry that rises above the weirs
373. As liquid flows through the brew chamber assembly 312 into the
coffee pot (see pot 16 in FIG. 2A), the liquid level L (FIG. 6B) in
the brewing chamber decreases and the ground coffee in the slurry
begins to settle. A substantial portion of the ground coffee 400
settles on the top surfaces of the weirs as shown in FIG. 6B,
thereby preventing a flow restrictive (i.e. thick) layer of coffee
grounds from forming on the filter.
Referring to FIG. 2A, brewing chamber assembly 12 (or,
alternatively, brewing chamber assembly 312 of FIGS. 6A and 6B)
mounts to a cover 84 which is attached to rear wall 24 of the
housing 10. Cover 84 has an opening 86 through which discharge end
54 of the discharge tube 48 extends.
When brewing chamber assembly is mounted to the cover, tube 76 is
made to extend through valve body 14. Valve body 14 is mounted to
side wall 20 and back wall 24 of the housing 10. Generally
speaking, the valve body 14 includes a valve through which brewed
coffee flows to exit the brewing chamber 12. The rate at which the
coffee exits the control chamber is controlled by the valve in
order to control the brew time of the coffee. For example, assume a
brew time of two minutes is desired and further assume that a
volume of twelve cups of coffee is to be made. There will be a
large volume of water in the brewing chamber during brewing, and
because it will take that large volume a longer time to exit the
brewing chamber than it would a smaller volume, the flow rate out
of the brewing chamber must be relatively high in order for all of
the brewed coffee to have exited the brewing chamber at the end of
the two minute brew time. On the other hand, when only four cups of
coffee are to made, the flow rate out of the brewing chamber will
be slower in order that water in the brewing chamber can remain in
contact with the coffee grounds for the full two minutes.
The control valve which controls the rate of flow of brewed coffee
out of the brewing chamber is shown in FIGS. 7A and 7B, which are
cross-sectional bottom views of the valve body 14. As shown, the
valve body 14 has a rectangular opening 88, which extends
completely through the valve body in a vertical direction, and a
second opening 89 which extends from the back 24 of the housing
towards the from 94 of the valve body and which does not pass
completely through the valve body. The openings 88 and 89 join one
another as shown in FIG. 7A. The silicone tube 76 which extends
from cone 70, see FIG. 4C, (or tubing 376 on cone 370, FIG. 6A)
extends downwardly through the opening 88.
A control knob assembly, designated generally as 98, includes a rod
102 extending through a bore which extends from front 94 of the
valve body 14 to the opening 88. The rod 102 includes a threaded
portion 103 which engages with threads 105 in the valve body. At
one end of the rod 102 is a control knob 100 which is located at
the front 94 of the valve body. The other end of the rod 102 abuts
a rocker arm 107 which is pivotal about rocker arm pivot 109 fixed
within the valve body 14.
Rocker arm 107 is in turn in abutment with a U-shaped yoke 111 that
has a pair of parallel arms 113. The yoke 111 is slidable within
the openings 88, 89 in a direction parallel to the longitudinal
axis of rod 102. Yoke 111 is biased in the position shown in FIG.
7A (i.e. towards back wall 24) by springs 121 extending between
yoke 111 and back wall 24.
A pair of wedge-shaped valve cams 115 are pivotally mounted to the
arms 113 by pivot pins 117. Each cam 115 has a rounded side which
faces the rounded side of the other cam. Tube 76 is positioned
between the rounded sides of the cams as shown.
Each valve cam 115 has a guide pin 119 which is slidable within a
guide slot (not shown, but its orientation relative to the pins is
shown in dashed lines and designated 119 in FIGS. 7A and 7B) in
valve body 14.
FIG. 7A shows the control valve assembly in a fully open position.
To close the valve, control knob 100 is rotated in the direction
indicated in FIG. 7B, causing rod 102 to advance within the valve
body due to the interaction of threaded portion 103 with threads
105. As rod 102 advances, it pushes against the rocker arm causing
the rocker arm to pivot about rocker arm pivot 109 and to in turn
push the yoke 111 towards the front 94 of the valve body 14. As the
yoke 111 moves forward, it causes the cams 115 to pivot in the
direction of the arrows shown in FIG. 7B and to thereby squeeze the
tube 76 between themselves. The yoke may also be moved forward in
other ways within the scope of the present invention, such as by a
leadscrew coupled between it and an electric motor. To open the
valve, knob 100 is rotated in the direction indicated in FIG. 7A,
causing rocker arm 107 to pivot away from yoke 111 and permitting
yoke 111 to slide by action of springs 121 towards back wall 24.
This backwards movement of the yoke 111 causes the cams 115 to
pivot into the orientation shown in FIG. 7A and to thereby relieve
compression on the tube 76.
The degree by which the cams 115 are made to constrict the tubing
76 is dependent upon the flow rate which, for a given volume of
coffee, is needed in order to expose liquid to the grounds for the
desired brew time. FIG. 9 shows an example of markings which may be
imprinted on the valve body 14 surrounding the control knob 100 in
order to inform a user as to how far the knob should be turned in a
certain direction for a desired brew time. Arrow 112 is printed on
control knob 100. As shown in the example of FIG. 9, for each
volume of coffee (e.g. 4 cups, 8 cups, 12 cups) available to be
made by the coffee maker, there is a range of brew times which
extends from minimum ("min") to maximum ("max"). This preferably
represents the 2 minute to 4 minute range of brew times at which
standard ground coffee has been found to be most successfully
brewed, and shorter durations for free ground coffee. Thus, for any
volume of coffee, the amount by which the silicone tubing is
constricted for a 2 minute brew time is less than the constriction
which will be used for a 4 minute brew time. Moreover, the amount
of constriction needed to brew four cups of coffee for a two minute
brew time is significantly more than that needed to brew twelve
cups of coffee for a two minute brew time, due to the differences
in volume between the two.
An alternative control valve design is shown in FIGS. 8A, 8B, and
8C. As shown, the valve body 14b has a substantially rectangular
opening 88b. A short wall 90 extends into the opening 88b near back
wall 24 of the housing 10. The silicone tube 76 which extends from
cone 70 (see FIG. 4C) extends through the opening 88b such that it
rests within a corner formed between short wall 90 and a side wall
91.
A threaded bore 92 extends through the valve body 14b from front 94
of the valve body 14b to the rectangular opening 88b. Bore 92 has a
reduced diameter section 96 which is not threaded.
A control knob assembly, designated generally as 98b, is disposed
within the bore 92. Control knob assembly 98b includes a rod 102b
extending into the bore 92. At one end of the rod 102b is a control
knob 100b which is located at the front 94b of the valve body. At
the other end of the rod 102b is a roller mount 104 and a roller
106 mounted to the mount by a pin 108 so that it spins axially
about the pin 108. The roller 106 is preferably made of rubber,
plastic, or any other suitable material. Rod 102b includes a
threaded portion 110 which is disposed within the threaded portion
of the bore 92.
The control valve operates to control flow rate out of the brewing
chamber by compressing the silicone tube 76 (or tube 376 of FIG.
6A) to restrict flow from it when a smaller volume of coffee is to
be made, in order to ensure that the heated water remains in
contact with the coffee grounds in the brewing chamber for the
desired brew time. When a large volume of coffee is to be made, it
is necessary to increase the flow rate through the valve so that
the liquid is not exposed to the coffee grounds for too long.
Little or no compression of the silicone tube is thus needed when
large quantities of coffee are to be brewed.
Referring to FIG. 8A, when control knob 100b is turned in the
direction of arrow A1, the interaction between the threaded portion
of bore 92 and threaded sleeve 110 causes the control knob assembly
98 to move in the direction of arrow A2, away from the silicone
tube 76. This is the "open" condition, at which maximum flow rate
out of the brewing chamber is achieved, because there is no
pressure by the roller 106 against the silicone tube 76.
When control knob is turned in the direction of arrow A3 in FIG.
8B, control knob assembly 98 moves in the direction of arrow A4.
The roller 106 thus presses against the silicone tubing 76 to
constrict the tubing. Because the tube 76 is positioned in a
corner, however, its opening cannot be completely constricted by
the roller.
Operation of the preferred embodiment will next be described. At
the start of the coffee making process, the brewing chamber
assembly 12 is disconnected from the coffee maker and the screen
component 64 is separated from the cone 70. A user places a clean
filter 78 in cone 70, and assembles the brewing chamber assembly 12
into the configuration shown in FIG. 3. The user next puts the
appropriate quantity of ground coffee into the screen component
64.
The preferred quantities of grounds are: 10 scoops (where a
standard coffee scoop is approximately 2 tablespoons) for 12 cups
of coffee; 62/3 scoops for 8 cups of coffee; and 31/3 scoops for 4
cups of coffee for regular grind coffee (preferably using No. 7
grind coffee). Where an "espresso grind" is preferred, 71/2 scoops
of No. 5 grind coffee is used to make 4 cups of coffee.
The grounds are initially trapped by the screen 68, but later
approximately 30% of the grounds fall through to the filter after a
slurry is formed by the grounds and the heated water. The grounds
may also be placed directly on the filter. In such a case, the
grounds are carried through the screen as the grounds and the
heated water form a slurry. Approximately 30% of these grounds then
fall through the screen and onto the filter after liquid begins to
drain from the chamber.
Next, the brewing chamber assembly 12 is mounted in the housing 10,
such that screen holder 66 is coupled to the cover 84 and such that
tube 76 is fed through opening 88 (FIG. 7A) of valve body 14 as
shown in FIG. 7A.
If brew chamber assembly 312 of FIGS. 6A and 6B is used, extension
371 is first separated from cone 370, a clean filter 378 is placed
in cone 370, and extension 371 is re-attached to cone 370. Ground
coffee is scooped into the cone 370 and the brewing chamber 312 is
mounted in the housing such that extension 371 is coupled to the
cover 84 and such that tube 376 is fed through opening 88 of valve
body 14 and positioned between the cams 115.
Next, cap 42 is removed from fill tube 40 (FIG. 2A), and a volume
of cool or room temperature, or partially heated or preheated water
equivalent to the volume of coffee to be brewed is poured through
fill tube 40 and into vessel 32. It may also be desirable to use a
quantity that is slightly more than the desired volume of coffee to
account for losses due to absorption of water in the coffee grounds
and to a smaller percentage due to steam evaporation. The cap 42 is
then sealed in place on top of fill tube 40.
The user turns power switch 58 (FIG. 1) to the "on" position to
activate heater 56. As the water in vessel 32 becomes heated, its
volume increases. Vent 44 prevents this increase in volume from
causing the water to flow through discharge tube 48 and onto the
coffee grounds by allowing some of the air displaced by the
expanding water to leave the vessel 32.
Once the water begins boiling, steam fills the space within the
vessel 32 which lies above the water surface W. A small amount of
steam is expelled by vent 44. Because the vent is small, the rate
of steam production far exceeds the rate at which steam is released
from the vent 44, and so pressure within the vessel 32 continues to
increase.
The increased pressure inside the chamber forces the water
downwardly in the vessel, and pushes it through discharge tube 48.
The maximum pressure reached within the vessel 32 is approximately
15 inches of water. The rate at which heated water flows through
discharge tube 48 is substantially constant (and is a function of
the discharge tube size and the rate of steam production within the
vessel). The preferred discharge tube diameter of 0.5 inches was
selected for the preferred embodiment because it provides a
constant flow and because it provides a flow rate that is
sufficiently strong to cause complete mixing of water and grounds
in the brewing chamber. The preferred embodiment pumps 12 cups (1.8
liters) of water out of vessel 32 in approximately 30 seconds. This
is advantageous over prior art systems, such as the thermal pump
system, because it delivers water to the brewing chamber at or near
the industry-recommended temperature of 205.degree. F. By contrast,
the thermal pump systems deliver water at temperatures of between
170.degree. and 185.degree. F. to the brewing chamber.
It may also be desirable to configure the chamber such that water
pre-heated and is maintained at an elevated temperature, and then
elevated to the brewing temperature upon activation of a switch by
the user. The heating chamber/discharge tube 48 may also be
replaced by a heating chamber which is positioned directly above
the brewing chamber and which, upon reaching brewing temperature,
releases the water directly into the brewing chamber. In such a
system, the temperature may be detected by a sensor such as one of
the sensor types described with respect to FIG. 18, and release of
the water into the brewing chamber may be carried out by use of a
solenoid arrangement of the type described with respect to the
embodiment of FIG. 18.
A third embodiment of a control valve assembly 98c is shown in
FIGS. 10A and 10B. This control valve assembly 98c includes a rod
102c extending into a threaded bore 92c formed in the valve body
14c. At one end of the rod 102c is a control knob 100c which is
located at the front 94c of the valve body 14c. The other end of
the rod 102c is in contact with the silicone tube 76 extending from
cone 70 (see FIG. 4C, or tubing 376 from cone 370, FIG. 6A), which
extends through a substantially rectangular opening 88c in the
valve body 14c. By rotating the control knob 100c in the manner
described above, the rod 102c is made to constrict (FIG. 10A) or
release (FIG. 10B) the silicone tubing 76.
A fourth embodiment of a valve body 14d is shown in FIGS. 11A and
11B. As with the other valve body configurations, the valve body
14d includes an opening 88d through which the silicone tubing 76
from cone 70 (see FIG. 4C) at least partially extends. A stepper
motor 130 is mounted to back wall 24d of the coffee maker housing
10 (housing shown in FIGS. 1-2B). A plunger 132 having a beveled
end extends from the stepper motor 130 and through an opening in
the back wall 24c. The plunger 132 and stepper motor 130 are
coupled to one another such that activation of the stepper motor
130 moves the plunger 132 incrementally towards or away from the
tube 76 in response to application of a drive signal to the stepper
motor 130.
FIG. 12 is a simplified schematic diagram illustrating a coffee
brewing system embodying the fourth embodiment of the valve body
14d. A user interface device 134 (which may be a keypad, dial, or
any other form of input device) is provided which enables a user to
input volume information representing the amount of coffee to be
brewed (e.g. 4 cups, 6 cups, etc.) and to input the desired brew
time (e.g. 2 minutes or 4 minutes). Alternatively, the apparatus
may be pre-set to provide only a single brew time, such as 4
minutes, in which case the user input would relate only to the
volume to be brewed. The user interface 134 interfaces with stepper
motor 130 via a controller 136 which generates drive signals
responsive to the user input.
The steps carried out by the system of FIGS. 11A and 11B are
illustrated in the simplified flow diagram of FIG. 13. At step 500,
input is received from the user (via interface 134). Controller 136
converts the input to drive signals for the stepper motor at step
502. It is preferable for the controller 136 to include memory
tables representing the flow rates needed to achieve the desired
brew times for the selected volumes. Also stored in the controller
are data representing the drive signals needed to activate the
stepper through the number (and direction) of step increments which
will advance plunger 132 to constrict the tube 76 by the amount
which will achieve the flow rate for the desired brew time. Thus,
at step 502, the controller first determines the flow rate needed
to give the appropriate desired brew time for the desired volume,
and it then determines the stepper motor drive signals needed to
constrict or open tube 76 by an amount which will achieve that flow
rate.
Finally, at step 504, the drive signals are delivered to the
stepper motor and the stepper motor is activated to set the
aperture opening of the tube 76 (i.e. to constrict or release
pressure against the tube by the plunger 132). After the aperture
of the tube 76 is set, the brewing cycle is initiated at step 506
by manual activation of a power switch as described above or by
other means (such as delivery of a signal by the controller 136 to
the heater 56 of FIG. 2A).
In the above-described embodiments, flow rate is controlled (in
order to achieve a predetermined brew time) by the use of various
means for restricting flow through a silicone tube which discharges
brewed coffee into a coffee pot or other receptacle. It should be
appreciated that numerous other means for controlling the flow rate
and/or setting the brew time may be utilized without exceeding the
scope of the present invention.
For example, referring to the fifth embodiment of FIGS. 14 through
17, a brewing chamber 200 may be provided which includes a pair of
nested cones 202, 204. A first aperture 206 is formed in the floor
of inner cone 204, and a second aperture 208 is formed in the floor
of outer cone 202. The brewing chamber 200 may be mountable within
a housing similar to the housing 10 in FIG. 1, or it may be
provided with flanges 211 which allow it to be placed directly on
top of a coffee receptacle.
Inner cone 204 is manually rotatable within outer cone 206. A lip
210 extends from the upper perimeter of the inner cone 204 to
facilitate grasping of the inner cone for rotation. As shown in
FIGS. 15A through 15D, rotation of inner cone 204 relative to outer
cone 202 causes aperture 206 in inner cone to move towards or away
from the aperture 208 in outer cone. When there is no overlap of
the apertures 206, 208, liquid cannot flow through the apertures
into an underlying coffee receptacle. As inner cone 204 is rotated
relative to outer cone 202, the aperture 206 begins to overlap the
aperture 208 to increase the effective opening of the apertures as
shown in FIGS. 15B-15D, and to thereby increase the rate at which
liquid will flow out of the brewing chamber 200. It should be
appreciated that other configurations, in which a first body having
apertures is moved relative to a second body having second
apertures in order to increase or decrease partial overlap of the
apertures, may likewise be used within the scope of the present
invention.
Referring to FIGS. 16 and 17, an indicator arrow 212 extends
downwardly from the lip 210. Printed on the exterior surface of the
outer cone 206 are markings representing the volume of coffee to be
brewed (see FIG. 16) and/or the volume to be brewed in combination
with a range (preferably a "minimum" of 2 minutes and a "maximum"
time of 4 minutes) of available brew times (see FIG. 17). The
location of each marking is selected such that the flow rate of
liquid passing through the apertures gives the appropriate brew
time for the selected volume of coffee. For example, in the
embodiment of FIG. 16 a user desiring to brew four cups of coffee
would position indicator 212 into alignment with the markings
indicating "4 cups." In the embodiment of FIG. 17, which provides
the user with a short range of available brew times, a user
desiring to brew 4 cups of coffee using the maximum brew time of 4
minutes would rotate the inner cone 204 until the indicator 212 is
positioned as shown in FIG. 17. A user wishing to brew 8 cups of
coffee at the maximum brew time of 4 minutes would rotate inner
cone 204 until indicator 212 pointed to "max" in the "8 cups" band.
As with all of the brew times given herein, it should be pointed
out that the brew times described with respect to this embodiment
are used for illustration purposes only. The variations by design
and application are far greater than these examples.
Alternatively, a cone may be configured to have interchangeable
bottom inserts, each having differently-sized apertures each of
which permits release of coffee from the brew chamber into a coffee
pot at a different flow rate. Such a configuration would allow the
user to select an insert having apertures which would provide the
desired brew time for a particular volume of water.
A sixth embodiment of a control valve is shown in FIG. 18. In this
embodiment, which is particularly useful for brewing teas, the
heated water is held in the brewing chamber for the duration of the
desired brew time, and then quickly released into an underlying
container at the end of the brew time.
Referring to FIG. 18, tube 76 which extends from cone 70 is
equipped with a sensor 114 for detecting the presence of heated
water in the brewing chamber 14. The sensor 114 can be one of
several types of generally known sensors capable of sensing liquid,
an increase in mass, or an increase in temperature. For example,
the sensor 114 may be a thermocouple which detects an increase in
temperature in the tube 76. Alternatively, the sensor 114 may be a
conductivity probe which senses the presence of water inside the
tube, since water is more highly conductive than air.
The opening of the tube 76 is covered by a valve door 116. Valve
door 116 is pivotable about a pin 118 between an opened condition
(shown in dashed lines) and a closed position, and it is biased in
its opened condition by conventional means. A spring loaded
solenoid 120 is mounted to the valve body 14c, and includes a pin
122 which, when the solenoid 120 is in a non-energized state, abuts
the valve door 116 to hold it in the closed condition.
The sensor 114 is electrically coupled to an amplifier circuit 124
capable of amplifying a detection signal from the sensor
(indicating that heated water has entered the brewing chamber). A
timer 126 is electrically coupled to the amplifier circuit 124. An
input device 128 (such as a keypad, control knob, or other input
device) is also coupled to the timer 126. The output of the timer
126 is electrically coupled to the solenoid 120.
Prior to beginning the brewing process, a user uses the input
device 128 to set the timer 126 by inputting data corresponding to
the desired brew time. The user then activates the power switch for
the heating element as described above. Once the sensor 114 detects
the presence of heated water in the brewing chamber, it delivers a
signal to the timer 126 via amplifier circuitry 124. The timer 126
counts down for the desired brew time, at the end of which it
delivers a current pulse to solenoid 120.
Energization of solenoid 120 causes pin 122 to retract and to
thereby allow valve door 116 to pivot in accordance with its bias
into the open condition. The brewed coffee is thus released from
the chamber. For this embodiment, it is desirable to provide the
tube 76 to have as large a diameter as possible. This will allow
brewed coffee to exit the brewing chamber at a fast flow rate so as
not to increase the brew time. The time it takes for brewed coffee
to leave the chamber is calculated into, and is a function of, the
brew time.
In the sixth embodiment, a bi-metallic spring (not shown)
positioned within or adjacent to the brewing chamber may be used in
place of the sensor 114. Such a spring would mechanically deform in
response to the presence of heat and would be used to mechanically
activate the countdown timer 126.
Input Control
The above-described embodiments maintain a constant brew time
regardless of volume by controlling fluid flow out of the brewing
chamber. Fluid flow may alternatively be controlled at the input
side of the brewing chamber. In other words, the rate at which
heated water is pumped into the brewing chamber may be controlled
in order to maintain a predetermined brew time.
One embodiment of a coffee maker having input-side control is shown
in FIG. 19. Many of the components in the FIG. 19 embodiment are
like those of the preferred embodiment shown in FIG. 2A and will
not be re-described. However, unlike the preferred embodiment,
discharge tube 54e is formed of flexible silicone tubing and cover
84e is a valve body which has a control knob 55 and which may have
a structure similar to that of one of the valve bodies shown in
FIGS. 7A-7B, 8A-8B, 10A-10B, and 12A-12B. Thus, by turning knob 55,
a user can control the rate at which heated water flows into the
brewing chamber 12e. As with those embodiments, turning the knob
applies or removes pressure against the tube to alter its effective
area or aperture.
The FIG. 19 embodiment also differs from the preferred embodiment
in that body 14e is not a valve body but simply a body having a
wide discharge opening 15 which is aligned with a similarly
proportioned opening at the bottom of cone 70e. Since brew time
will be regulated by controlling the rate of flow into the brewing
chamber, the large diameter opening is desired so that coffee can
quickly drain from the brewing chamber 12e so as to not extend the
brewing time.
Many other means for controlling flow into the brewing chamber may
also be utilized without exceeding the scope of the present
invention. For example, a pump having a variable stroke rate can be
used to pump heated water into the brewing chamber. Alternatively,
the power to the heater (such as heater 56 in FIG. 2B) can be
varied to control the rate at which it pumps heated water into the
brewing chamber.
Conclusion
Several embodiments of a new system for making brewed beverages
have been shown and described. These examples have been described
by way of example and are not intended to limited the scope of the
appended claims. It should be appreciated that additional
embodiments may be devised (such as, but not limited to, by
combining the features of the various embodiments described above,
or by adding a pre-heat function for water in the reservoir) which
fall within the scope of the present invention.
* * * * *