Abstrict
A coffee or tea making machine wherein the housing has a container
for a supply of water and supports a holder for tea leaves or comminuted
coffee beans. A conduit connects the outlet of the container with
the holder, and a portion of such conduit is constituted by an electric
heater which has one or more thick film conductors in series with
an on-off switch and a relay which regulates the flow of current
from an energy source to the thick film conductor or conductors.
Such conductor or conductors can be applied directly to an insulating
carrier which can be made of a ceramic or plastic material and defines
a portion of the path for the flow of water from the container to
the holder. Alternatively, the carrier can be made of a metallic
material, such as aluminum, and then supports one or more insulating
covers at least one of which carries a thick film conductor. The
conductor or conductors are applied in the form of a paste which
is caused to dry on the insulating carrier or on the cover or covers.
Claims
I claim:
1. Machine for making hot beverages by contacting a heated liquid
with a flavoring agent, such as tea or coffee, comprising a housing
having a container for a supply of liquid; a holder supported by
said housing and arranged to contain a supply of flavoring agent;
and conduit means provided in said housing and defining a path for
the flow of liquid from said container to said holder, said conduit
means including an electric heater which defines a portion of said
path and includes at least one thick film conductor, switch means
in series with said conductor, and current regulating means in series
with said conductor.
2. The machine of claim 1, wherein said heater further comprises
a carrier which defines said portion of said path and has a plurality
of surfaces, said at least one conductor including a hardened paste-like
conductive material adjacent at least one of said surfaces.
3. The machine of claim 1, wherein said current regulating means
comprises a relay in series with said switch means, said at least
one thick film conductor having a first terminal connected with
said switch means and a second terminal connected with said relay.
4. The machine of claim 1, wherein said conduit means further includes
a riser between said heater and said holder to convey heated liquid
into contact with the flavoring agent.
5. The machine of claim 1, wherein said housing includes a portion
disposed beneath said holder and arranged to support a vessel for
the beverage, said holder having outlet means for dispensing beverage
into the vessel on said portion of said housing.
6. The machine of claim 1, wherein said heater further comprises
a metallic carrier which defines said portion of said path and at
least one cover of insulating material provided on said carrier
and supporting said at least one thick film conductor.
7. The machine of claim 6, wherein said portion of said path is
substantially U-shaped.
8. The machine of claim 6, wherein said carrier has an inlet for
liquid and an outlet for liquid, said conduit means further comprising
a liquid-supplying portion connecting said container with said inlet
and a liquid-evacuating portion connecting said outlet with said
holder.
9. The machine of claim 8 wherein said cover contains a ceramic
material.
10. The machine of claim 8, wherein said cover contains a plastic
material.
11. The machine of claim 8, wherein said cover has an upper side
and said at least one conductor is applied to said upper side.
12. The machine of claim 6, wherein said heater comprises a plurality
of substantially plate-like covers on said carrier.
13. The machine of claim 12, wherein said carrier has a plurality
of mutually inclined surfaces and each of said covers overlies a
different surface of said carrier.
14. The machine of claim 13, wherein said heater comprises a plurality
of thick film conductors, at least one for each of said covers.
15. The machine of claim 1, wherein said heater further comprises
a one-piece carrier of insulating material which defines said portion
of said path, said at least one thick film conductor being provided
directly on said carrier.
16. The machine of claim 14, wherein said portion of said path
is substantially V-shaped.
17. The machine of claim 16, wherein said carrier has spaced apart
first and second external surfaces, said first surface having an
inlet for admission of liquid into said portion of said path and
an outlet for evacuation of liquid from said portion of said path,
said portion of said path extending from said inlet close to said
second surface and thence to said outlet.
18. The machine of claim 1, wherein said heater comprises at least
two thick film conductors and said regulating means includes means
for selectively connecting said conductors with an energy source.
19. The machine of claim 18, wherein one of said conductors is
thicker than another of said conductors.
20. The machine of claim 18, wherein one of said conductors is
longer than another of said conductors.
Description CROSS-REFERENCE TO RELATED CASES
A machine for making coffee and other hot beverages which employs
electric heaters with thick film conductors is disclosed in my commonly
owned copending application Ser. No. 207,764 filed June 16, 1988.
A machine for making hot tea which employs an electric heater with
one or more thick film conductors is disclosed in my commonly owned
copending patent application Ser. No. 207,763 filed June 16, 1988.
My commonly owned copending patent application Ser. No. 056,852
filed June 1, 1987 by Erich Hoffmann (now U.S. Pat. No. 4,765,422
granted Aug. 23, 1988) discloses a bathroom scale with a strain
gauge employing a resistor which is a thick film conductor.
My commonly owned copending patent application Ser. No. 056,855
filed June 1, 1987, now abandoned discloses a printed circuit with
one or more thick film conductors for use in an electric hair dryer.
My commonly owned copending patent application Ser. No. 056,854
filed June 1, 1987 discloses a rotor for an electrical machine wherein
the commutator comprises thick film conductors.
BACKGROUND OF THE INVENTION
The invention relates to machines for making hot beverages, such
as coffee, tea and chocolate. More particularly, the invention relates
to improvements in machines of the type wherein a stream of water
or another liquid (such as milk) is caused to flow from a container
in or on the housing of the machine, through an electric heater
and into a holder for a supply of flavoring agent, such as comminuted
coffee beans, tea leaves, chocolate powder or the like.
Machines of the above outlined character are known and are in extensive
use. In many instances, the conduit means for conveying hot water
or another liquid from the electric heater to the holder for a supply
of flavoring agent comprises a riser which discharges hot water
into the holder, and the latter has a sealable outlet at level above
a support (such as a warming plate) for a coffee pot, a teapot or
any other suitable vessel for heated beverages.
The electric heaters of presently known coffee making and like
machines normally comprise a metallic tube which is mounted on a
carrier and contains a heating spiral. The latter is normally embedded
in a supply of magnesium oxide powder. The metallic tube is adjacent
a conduit which conveys the liquid to be heated. A heater of the
just outlined character normally comprises a substantially U-shaped
metallic tube for the heating spiral and a substantially U-shaped
conduit for the liquid. Cold liquid enters by way of one leg of
the U-shaped conduit, and heated liquid leaves the heater by way
of the other leg of such conduit.
A drawback of the just described electric heaters is that the rate
of heat transfer between the metallic pipe and the liquid in the
conduit is not very satisfactory. Moreover, such heaters generate
noise and their initial cost is high. Still further, these heaters
must be used jointly with auxiliary components such as thermostats
and/or specially designed safety fuses. Certain electric heaters
of the above outlined character further employ a diode, especially
if the machine is to be converted from the making of a relatively
small quantity of coffee or another beverage to the making of a
larger quantity of such beverage or vice versa. The diode is used
to conform the quantity of electrical energy which is supplied to
the heating spiral to the selected quantity of the beverage. Such
auxiliary components contribute significantly to the cost of the
machine and render it prone to malfunction.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the invention is to provide a novel and improved machine
for making hot beverages which is simpler, less expensive and less
prone to malfunction than a conventional machine.
Another object of the invention is to provide a novel and improved
electric heater for use in a coffee making, a tea making or a like
machine.
A further object of the invention is to provide an electric heater
whose heating capacity is relatively small so that it can immediately
react to changes of the quantity of liquid to be heated.
An additional object of the invention is to provide an electric
heater which can be installed in certain existing machines as a
superior substitute for heretofore known electric heaters.
Still another object of the invention is to provide an electric
heater which need not employ a metallic pipe for a heating spiral
and whose efficiency is superior to that of conventional heaters.
A further object of the invention is to provide a novel and improved
carrier of electric conductors for use in the above outlined heater.
An additional object of the invention is to provide novel and improved
electric conductor means for use in the above outlined electric
heater.
The invention is embodied in a machine for making hot beverages
(such as coffee, tea or chocolate) by contacting a heated liquid
(such as water or milk) with a flavoring agent. The improved machine
comprises a housing having a permanently installed or detachable
container for a supply of the liquid, a holder which is supported
by the housing and serves to contain a supply of flavoring agent
(such as comminuted coffee beans, tea leaves or chocolate powder),
and conduit means provided in the housing and defining a path for
the flow of liquid from the container to the holder. The conduit
means includes an electric heater which defines a portion of the
path and includes at least one thick film conductor, switch means
in series with the thick film conductor, and a relay or other suitable
current regulating means in series with the thick film conductor.
The heater can further comprise a carrier which defines the aforementioned
portion of the path and has a plurality of surfaces. The at least
one conductor includes a hardened paste-like conductive material
which is applied (directly or indirectly) to at least one surface
of the carrier. The current regulating means can be connected in
series with the switch means; for example, one terminal of the at
least one thick film conductor can be connected with the switch
means and another terminal of the at least one conductor can be
connected with the current regulating means. The conduit means can
further comprise a riser which serves to convey heated liquid from
the heater to the holder, i.e., into contact with the flavoring
agent. A portion of the housing (such as a base or leg) can be disposed
beneath the holder to support a coffee pot, a tea pot or another
suitable vessel for the beverage. The holder has a sealable outlet
which can dispense hot beverage into the vessel on the aforementioned
portion of the housing.
The heater can comprise a metallic carrier (e.g., a block made
of aluminum) which defines the aforementioned portion of the path
and at least one cover of insulating material on the carrier to
support one or more thick film conductors. The path portion which
is defined by the carrier can be substantially U-shaped, and the
carrier can be provided with an inlet for admission of liquid into
and with an outlet for evacuation of heated liquid from the U-shaped
portion of the path. The conduit means can further comprise a first
portion which connects the inlet of the carrier with the container
and a second portion which can include the aforementioned riser
and serves to convey heated liquid from the outlet of the carrier
to the holder. The cover or covers can contain a ceramic material,
a plastic material or any other suitable insulating material. The
arrangement is preferably such that a cover is provided on top of
the carrier and has an upper side to which the thick film conductor
or conductors are applied. The carrier can support a plurality of
substantially plate-like covers each of which may but need not carry
one or more thick film conductors. The covers can be applied to
several mutually inclined and/or parallel surfaces of the carrier.
The heater can comprise at least one thick film conductor for each
cover.
Alternatively, the heater can comprise a one-piece carrier of ceramic,
plastic or other insulating material which defines the aforementioned
portion of the path and is directly in contact with one or more
thick film conductors. The path portion which is defined by the
insulating carrier can be substantially V-shaped. It is presently
preferred to provide such insulating carrier with an inlet and an
outlet for liquid in a first surface of the carrier and to cause
the substantially V-shaped path portion to extend from the inlet,
close to a second surface which is remote from the first surface,
and thereupon to the outlet. This ensures that the conveyed liquid
is in highly satisfactory heat exchanging contact with the carrier.
If the heater comprises two or more thick film conductors, the
regulating means can be designed to selectively connect one, two
or more conductors with a suitable energy source. Furthermore, at
least one of the plural conductors can be thicker than at least
one other conductor and/or at least one of the conductors can be
longer than at least one other conductor.
The novel features which are considered as characteristic of the
invention are set forth in particular in the appended claims. The
improved machine itself, however, both as to its construction and
its mode of operation, together with additional features and advantages
thereof, will be best understood upon perusal of the following detailed
description of certain specific embodiments with reference to the
accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is an elevational view of a machine which embodies one form
of the invention, with portions of the housing, liquid container
and conduit means broken away;
FIG. 2 is an end elevational view of the electric heater as seen
from the left-hand side of FIG. 1;
FIG. 3 is a sectional view as seen in the direction of arrows from
the line III--III of FIG. 2;
FIG. 4 is a plan view of the heater which is shown in FIG. 2;
FIG. 5 is a sectional view as seen in the direction of arrows from
the line V--V of FIG. 4;
FIG. 6 is an enlarged perspective view of a second heater;
FIG. 7 is a sectional view, similar to that of FIG. 3, of a third
heater; and
FIG. 8 is an end elevational view as seen from the underside of
FIG. 7.
DESCRIPTION OF PREFERRED EMBODIMENTS
The drawing shows only those parts of the improved machine which
are necessary for full understanding of the invention. For example,
the drawing does not show a cable for connection of the heater to
a source of electrical energy and/or all of the conductors between
such cable and the heating element. All parts which are not shown
in the drawing but are necessary for proper operation of the machine
can be identical with or analogous to the corresponding parts of
conventional machines, for example, those known as Coffee Maker
No. 152, Coffee Maker No. 154, Coffee/Tea Maker No. 164 and Coffee/Tea
Maker No. 165 (all produced by the assignee of the present application).
For example, the machine 10 which is shown in FIGS. 1 to 5 can
be used to make hot coffee and includes a substantially L-shaped
housing 11 which is made of an electrically insulating material.
The portion 12 of the housing 11 constitutes a substantially horizontal
leg which is hollow and supports a warming plate 47 for a vessel
44, such as a coffee pot. The underside of the housing portion 12
can come to rest directly on a table, on a counter or on any other
suitable support. The upright portion or leg of the housing 11 supports
or is integral with a container 13 for a supply of water, milk or
another liquid which is to be heated prior to being brought into
contact with a flavoring agent, such as comminuted coffee beans.
In the embodiment which is shown in FIG. 1, the container 13 is
a discrete part which has a bottom wall 14 provided with at least
one but preferably two or more coupling elements 15 engageable with
complementary coupling elements of the upright portion of the housing
11.
The bottom wall 14 of the container 13 is provided with two nipples
16 (only one can be seen in FIG. 1) one of which serves to admit
relatively cold liquid into a pipe 21 leading to an electric heater
22 and the other of which receives heated liquid from a pipe 18
and conveys such liquid to the lower end portion of a riser 17 which
is or can be installed in the container 13. The upper end portion
of the riser 17 delivers heated liquid into a horizontal pipe 39
having an outlet 40 for admission of heated liquid into the interior
of a holder 38 for a supply of flavoring agent. For example, the
holder 38 can be designed to receive a conical filter paper (not
shown) for a supply of comminuted coffee beans. The sealable outlet
41 of the filter holder 38 is disposed at a level above the cover
45 of the vessel 44 resting on the warming plate 47. The holder
38 has a handle 42, and the vessel 44 has a handle 46. The character
43 denotes a closure or lid which can be removed or lifted in order
to afford access to the interior of the container 13, i.e., to replenish
the supply of liquid therein.
The vessel 44 can be made of a light-transmitting (preferably transparent)
material, and its cover 45 has a centrally located opening for admission
of hot beverage when such beverage is dispensed by way of the outlet
41 of the holder 38. The latter can be designed to accommodate a
larger or a smaller supply of flavoring agent, depending on the
desired number of cups of hot beverage. The warming plate 47 for
the bottom wall of the vessel 44 is preferably heated by the electric
heater 22. A suitable seal, such as a silicon seal, can be interposed
between the warming plate 47 and the portion or leg 12 of the housing
11.
The manner in which the holder 38 can be converted to accept larger
or smaller quantities of a flavoring agent is disclosed, for example,
in commonly owned copending patent application Ser. No. 184,682,
now U.S. Pat. No. 4,843,955 filed Apr. 22, 1988 by Stefan Henn and
Klaus Beumer for "Machine for brewing coffee and other hot
beverages" and in commonly owned copending patent application
Ser. No 184,683, now U.S. Pat. No. 4,790,240 filed Apr. 22, 1988
by Stefan Henn and Rudolf Maass for "Machine for brewing hot
beverages".
The electric heater 22 in the hollow portion or leg 12 of the housing
11 has a U-shaped passage or channel 32 which constitutes a portion
of an elongated path for the flow of liquid from the container 13,
through the heater 22 and into the holder 38. The path is defined
by a composite conduit which includes the nipples 16 in the bottom
wall 14 of the container 13, the pipes 21 and 18, the riser 17,
the pipe 39 and the electric heater 22. At least one of the pipes
18, 21 can be made of a flexible elastic material so as to be capable
of sealingly engaging the respective nipples 16 of the bottom wall
14 as well as the inlet 20 and outlet 19 of a substantially block-shaped
metallic carrier 31 forming part of the heater 22. The direction
of flow of a stream of liquid through the carrier 31 of the electric
heater 22 can be best seen in FIG. 6 which shows that the pipe 21
admits liquid to the inlet 20 in the direction of arrow A and that
the outlet 19 of the carrier 31 admits heated liquid to the pipe
18 which conveys such liquid in the direction of arrow B, namely
into the riser 17.
The heater 22 in the portion 12 of the housing 11 is or can be
constructed in a manner as shown in FIGS. 2-5. The aforementioned
carrier 31 is a substantially flat block-shaped metallic body having
an upper side or surface facing the warming plate 47 and four vertical
sides or surfaces. The inlet 20 and outlet 19 extend from one of
the vertical sides. The other three vertical sides are overlapped
by the respective portions of a cover 33 which also overlies the
upper side of the carrier 31. The cover 33 is made of an insulating
material (such as a ceramic or a plastic substance) and carries
a plurality of thick film conductors 34, 35, 36 and 37. The U-shaped
passage or channel 32 of the carrier 31 has a circular cross-sectional
outline and extends close to the four portions of the cover 31 and
hence close to the conductors 34-37 at the outer side of the cover.
The carrier 31 can be made of aluminum and its inlet 20 and outlet
19 face rearwardly, namely toward the container 13. The cover 33
can be bonded (adhesively secured) to the carrier 31.
FIG. 4 shows four pairs of thick film conductors 34-37 at the upper
side of the cover 31, i.e., adjacent the underside of the warming
plate 47. However, it is equally within the purview of the invention
to provide at least one thick film conductor on at least one additional
portion of the cover 31, i.e., on a portion which extends substantially
vertically to overlie one of the vertical sides of the carrier 31.
The conductors 34 to 37 form two groups, and the conductors of one
group are mirror images of the conductors of the other group. The
arrangement may be such that the conductors of one group are connected
to an energy source for the purpose of brewing of a relatively small
quantity of coffee, and the conductors of both groups are connected
to the energy source when the holder 38 contains a relatively large
supply of a flavoring agent. However, it is equally possible to
connect one, two or three conductors of each group to the energy
source for the brewing of a relatively small quantity of coffee,
and to connect all conductors to the energy source for the purpose
of brewing, for example, eight, ten or twelve cups. The two groups
are separated from each other by a relatively narrow gap which extends
vertically in the view of FIG. 4. Each of the eight thick film conductors
34-37 of FIG. 4 is U-shaped, the conductors 34 surround the conductors
35-37, the conductors 35 surround the conductors 36-37, and the
conductors 36 surround the conductors 37. The length of the conductors
34 exceeds the length of the conductors 35-37, and the length of
the conductors 36 is less than that of the conductors 35 but exceeds
the length of the conductors 37. The width of the conductors 34
exceeds that of the conductors 35, the width of the conductors 35
exceeds that of the conductors 36, and the width of the conductors
36 exceeds that of the conductors 37. The resistance of the conductors
is inversely proportional to their width (it being assumed that
the height of all conductors is the same).
FIGS. 7 and 8 show a modified electric heater having a block-shaped
carrier 33 of insulating material. This carrier has four vertical
sides or surfaces one of which is provided with an inlet 20 for
cold liquid and an outlet 19 for heated liquid. The passage or channel
32 in the carrier 33 of FIGS. 7 and 8 is substantially V-shaped
and extends from the inlet 20 to the vertical surface opposite the
inlet 20 and outlet 19, and thereupon to the outlet 19. At least
one side, e.g., the upper side, of the carrier 33 of FIGS. 7 and
9 is provided with one or more thick film conductors (not specifically
shown) which may but need not be distributed in a manner as shown
in FIG. 4. For example, the carrier 33 of FIGS. 7 and 8 can support
one or more substantially circular, oval or like thick film conductors
(this also applies for the electric heater 22 of FIGS. 2-5). By
way of example, the carrier 33 of FIGS. 7 and 8 can be made of a
suitable ceramic material which is an electrical insulator. The
V-shaped passage or channel 32 has a substantially or exactly circular
cross-sectional outline; however, it is equally possible to provide
the carrier 31 of FIGS. 2-5 or the carrier 33 of FIGS. 7-8 with
a passage 32 having an oval or polygonal cross-sectional outline.
The V-shaped passage or channel 32 can be replaced with a composite
passage including two bores or holes which are inclined relative
to each other and communicate with one another close to one vertical
side of the carrier 33. It will be noted that the inlet 20 and outlet
19 extend from the major portion of the carrier 33.
FIG. 6 shows that the heater 22 comprises a block-shaped carrier
which resembles the carrier 33 of FIGS. 7-8 except that its inlet
20 is parallel with the outlet 19. The upper side of the carrier
33 is provided with a single thick film conductor 23 which resembles
a spiral. One end portion 24 of this conductor is connected with
one terminal 29 of an electric switch 27 by a line 26, and another
line 26 connects the other terminal 29 of the switch 27 with the
corresponding terminal of a relay 30. A third line 26 connects the
other end portion 25 of the thick film conductor 23 with another
terminal of the relay 30. The manner in which the relay 30 is connected
with an energy source is not shown in FIG. 6. The terminals 29 of
the switch 27 (which is a commercially available component with
a pivotable actuator 28) can be soldered to the respective lines
26. The switch 27 is an on-off switch. The relay 30 can be of the
type known as CMOS which is distributed by Motorola.
The relay 30 can be designed to regulate the flow of current through
the thick film conductor 23 in the following way: When the switch
27 is actuated at 28 to complete the circuit of the heater 22, the
output is 500 watts for a period of 8 minutes. The relay 30 thereupon
automatically reduces the power to 30 watts which suffices to ensure
that the warming plate 47 can maintain the beverage in the vessel
44 at an optimum temperature. The heater 22 can be automatically
disconnected from the energy source by way of the relay 30 (e.g.,
after the elapse of a selected further interval of time), or such
disconnection can be effected by way of the switch 27 which is in
series with the conductor 23 and with the relay 30.
The thick film conductors 34-37 can be applied in the form of a
paste which is thereupon caused or permitted to set. A heater employing
one or more thick film conductors is simpler, less expensive and
less prone to malfunction than conventional electric heaters of
the type presently used in coffee making and like machines for the
making of hot beverages. Thus, the improved heater (especially that
shown in FIG. 6 or in FIGS. 7 and 8) comprises a small number of
parts each of which can be mass produced at a low cost. The improved
heater is a self-regulating PTC (positive temperature control) heater
which can dispense with thermostats, safety fuses and/or diodes
because the functions of such auxiliary components are performed
by the aforediscussed elements of the heater.
The manner of making a paste which is to form one or more thick
film conductors is well known in the art, the same as the manner
of applying such paste to a support. Reference may be had, for example,
to published European patent application Ser. No. 0 158 779 which
fully discloses suitable materials for the making of paste as well
as methods of applying paste to supports for thick film conductors.
The improved machine is susceptible of many additional modifications
without departing from the spirit of the invention. For example,
the shape, size and/or other features of the heater 22 can be changed
in order to conform the heating capacity and/or the dimensions of
the heater to requirements in a particular housing and for a particular
machine. The passage or channel 32 in the carrier 31 or 33 can assume
a shape which deviates from that shown in FIGS. 3 or 7, and the
passage or channel can have a cross-sectional outline which is not
circular or which is circular in part only. Still further, the number,
width, length and/or configuration of thick film conductors can
be varied practically at will. The relay 30 can perform other functions
in addition to that of regulating the supply of electrical energy
to the thick film conductor or conductors. The improved heater can
be used in many types of coffee makers, tea makers or other machines
for the making of hot beverages.
Without further analysis, the foregoing will so fully reveal the
gist of the present invention that others can, by applying current
knowledge, readily adapt it for various applications without omitting
features that, from the standpoint of prior art, fairly constitute
essential characteristics of the generic and specific aspects of
my contribution to the art and, therefore, such adaptations should
and are intended to be comprehended within the meaning and range
of equivalence of the appended claims.
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