U.S. patent application number 11/722976 was filed with the patent office on 2008-10-30 for cooking appliance comprising at least one gas sensor array, sampling system for such a cooking appliance, method for cooking using said cooking appliance and method for cleaning said cooking appliance.
This patent application is currently assigned to RATIONAL AG. Invention is credited to Michael Greiner, Kathrin Hildenbrand, Judith Imgram, Andrea Jurgens, Jurgen Klasmeier, Katrin Lauterbach, Bruno Maas, Erwin Schuller, Roland Sterzel.
Application Number | 20080264269 11/722976 |
Document ID | / |
Family ID | 36096313 |
Filed Date | 2008-10-30 |
United States Patent
Application |
20080264269 |
Kind Code |
A1 |
Sterzel; Roland ; et
al. |
October 30, 2008 |
Cooking Appliance Comprising at Least One Gas Sensor Array,
Sampling System for Such a Cooking Appliance, Method for Cooking
Using Said Cooking Appliance and Method for Cleaning Said Cooking
Appliance
Abstract
A cooking appliance comprises at least one cooking compartment,
at least one installation compartment, at least one gas sensor
array for detecting the atmosphere within the cooking compartment,
the atmosphere within the installation compartment, and/or the
atmosphere surrounding the cooking appliance. The gas sensor
array(s) have at least two separate, different individual sensors
and/or at least one coherent sensor field including at least two
different sensor segments. The cooking appliance additionally
includes at least one storage unit for storing signals detected by
the gas sensor array(s), at least one evaluation unit for
processing the detected signals, at least one control unit for
controlling cooking or cleaning processes, at least one first feed
line for transporting the atmosphere from the cooking appliance to
the gas sensor array(s), and at least one valve at the inlet and/or
in the area of the first feed line.
Inventors: |
Sterzel; Roland; (Frankfurt,
DE) ; Greiner; Michael; (Johann-Ferstl Strasse,
DE) ; Jurgens; Andrea; (Westendstrasse, DE) ;
Imgram; Judith; (Albanusstrasse, DE) ; Klasmeier;
Jurgen; (Platanestrasse, DE) ; Lauterbach;
Katrin; (Valentin-Kindlin-Strasse, DE) ; Hildenbrand;
Kathrin; (Wachsenberg, DE) ; Maas; Bruno;
(Bichel, DE) ; Schuller; Erwin; (Moosbauerweg,
DE) |
Correspondence
Address: |
MARSHALL, GERSTEIN & BORUN LLP
233 S. WACKER DRIVE, SUITE 6300, SEARS TOWER
CHICAGO
IL
60606
US
|
Assignee: |
RATIONAL AG
Landsberg/Lech
DE
|
Family ID: |
36096313 |
Appl. No.: |
11/722976 |
Filed: |
December 22, 2005 |
PCT Filed: |
December 22, 2005 |
PCT NO: |
PCT/DE05/02311 |
371 Date: |
September 17, 2007 |
Current U.S.
Class: |
99/331 ;
219/413 |
Current CPC
Class: |
F24C 7/08 20130101; G01N
33/0031 20130101 |
Class at
Publication: |
99/331 ;
219/413 |
International
Class: |
F24C 7/08 20060101
F24C007/08 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 27, 2004 |
DE |
10 2004 062 737.1 |
Claims
1-39. (canceled)
40. Cooking appliance comprising: at least one cooking compartment;
at least one installation compartment; at least one gas sensor
array for the detection of at least one of the atmosphere of the
cooking compartment, the atmosphere of the installation
compartment, and the atmosphere surrounding the cooking appliance;
the at least one gas sensor array comprising at least two separate,
different individual sensors, or at least one coherent sensor field
comprising at least two different sensor segments; at least one
memory unit for storing the signals detected by the gas sensor
array; at least one evaluation unit for processing the detected
signals; at least one control unit for controlling at least one of
a cooking process and a cleaning process depending on the evaluated
signals; at least one first feed for communicating the atmosphere
of the cooking compartment to the gas sensor array, the at least
one first feed comprising an inlet; and at least one valve disposed
at the inlet or in the area of the first feed.
41. Cooking appliance according to claim 40, wherein the cooking
appliance comprises an aeration system for the cooking
compartment.
42. Cooking appliance according to claim 41, wherein the at least
one gas sensor array detects the atmosphere of the aeration
system.
43. Cooking appliance according to claim 41, wherein the at least
one gas sensor array comprises at least one of: a first gas sensor
array for the detection of the atmosphere of the cooking
compartment; a second gas sensor array for the detection of the
atmosphere of the installation compartment; a third gas sensor
array for the detection of the atmosphere of the aeration system;
and a fourth gas sensor array for the detection of the atmosphere
surrounding the cooking appliance.
44. The cooking appliance according to claim 43, wherein at least
one of the gas sensor arrays is arranged in at least one of the
cooking compartment, in the installation compartment, in the
aeration system, and outside the cooking compartment.
45. Cooking appliance according to claim 43, further comprising at
least one of: a second feed for transporting the atmosphere from
the installation compartment to at least one of the first, second,
third, and fourth gas sensor arrays; a third feed for transporting
the atmosphere from the aeration system to at least one of the
first, second, third, and fourth gas sensor arrays; and a fourth
feed for transporting the atmosphere surrounding the cooking
appliance to at least one of the first, second, third, and fourth
gas sensor arrays.
46. Cooking appliance according to claim 45, wherein at least two
of the first, second, third, and fourth feeds are connected to a
gas sensor array, directly or indirectly.
47. Cooking appliance according to claim 45, wherein at least one
gas sensor array is integrated into at least one of an inner wall
of the cooking compartment, an inner wall of the installation
compartment, and an outer wall of the cooking appliance.
48. Cooking appliance according to claim 47, wherein at least one
gas sensor array is integrated into at least two inner walls of the
cooking compartment.
49. Cooking appliance according to claim 45, further comprising at
least one pump unit in working connection with at least one of the
first, second, third, and fourth feeds for the transport of
atmosphere to at least one gas sensor array to be analyzed.
50. Cooking appliance according to claim 45, further comprising at
least one filter disposed in front of at least one gas sensor
array.
51. Cooking appliance according to claim 50, wherein the at least
one filter is disposed in front of a measuring surface of at least
one gas sensor array.
52. Cooking appliance according to claim 51, wherein the at least
one filter is disposed in or at the inlet of at least one of the
first, second, third, and fourth feeds.
53. Cooking appliance according to claim 43, further comprising at
least one first discharge from at least one of the first, second,
third, and fourth gas sensor arrays.
54. Cooking appliance according to one claim 53, further comprising
at least one valve disposed at the inlet or in the area of at least
one of the second feed, the third feed, the fourth feed, and the
first discharge.
55. Cooking appliance according to claim 54, wherein the control
unit controls the at least one valve.
56. Cooking appliance according to claim 40, wherein at least one
of the memory unit, the evaluation unit, and the control unit is
arranged in the installation compartment.
57. Cooking appliance according to claim 56, wherein at least one
of the memory unit, the evaluation unit, and the control unit is
integrated into one of a control and a regulation unit.
58. Cooking appliance according to claim 40, wherein the at least
one gas sensor array comprises several fields of a semiconducting
metal oxide film, to each of which two electrodes are connected,
whereby the fields form an essentially continuous surface, the
electrodes have a band-like shape and the continuous surface is
divided into fields in such a way that each field in the continuous
surface is delineated by two electrodes.
59. Cooking appliance according to claim 58, wherein at least one
of the different sensors, different sensor segments, and different
fields of the at least one gas sensor array exhibits different
conductivity changes as a function of at least one of a
temperature, composition, doping, and coating when they come into
contact with reducing or oxidizing gases.
60. Cooking appliance according to claim 59, wherein the
temperature of at least one of each sensor, sensor segment, and
field is adjustable.
61. Cooking appliance according to claim 60, wherein the
temperature is at least one of: manually adjustable through a
control panel of the cooking appliance, and automatically
adjustable through at least one of the evaluation unit and the
control unit.
62. Cooking appliance according to claim 59, wherein a certain
temperature gradient selected from a multiple number of temperature
gradients or a certain temperature profile selected from a multiple
number of temperature profiles can be applied to each gas sensor
array.
63. Cooking appliance according to claim 62, wherein the
temperature gradients and the temperature profiles are stored in
the memory unit.
64. Cooking appliance according to claim 62, wherein one of the
temperature, the temperature gradient, and the temperature profile
can be varied before or during a cooking process or cleaning
process.
65. Cooking appliance according to claim 62, further comprising at
least one of a thermocouple and a heating element assigned to at
least one of the one sensor, sensor segment, and field of the gas
sensor array.
66. Cooking appliance according to claim 65, wherein the at least
one of a thermocouple and heating element is controlled by the
control unit.
67. Cooking appliance according to claim 40, wherein the cooking
appliance comprises a hot air convection steam cooking
appliance.
68. Sampling system for a cooking appliance comprising: at least
one of: a first gas sensor array for the detection of the
atmosphere from a cooking compartment of the cooking appliance, a
second gas sensor array for the detection of the atmosphere from an
installation compartment of the cooking appliance, a third gas
sensor array for the detection of the atmosphere from an aeration
system of the cooking appliance, and a fourth gas sensor array for
the detection of the atmosphere surrounding the cooking appliance;
at least one of: a first feed for transporting the atmosphere from
the cooking compartment to at least one of the first, second,
third, and fourth gas sensor arrays, a second feed for transporting
the atmosphere from the installation compartment to at least one of
the first, second, third, and fourth gas sensor arrays, a third
feed for transporting the atmosphere from the aeration system to at
least one of the first, second, third, and fourth gas sensor
arrays, and a fourth feed for transporting the atmosphere
surrounding the cooking appliance to at least one of the first,
second, third, and fourth gas sensor arrays; and at least one valve
arranged at an inlet or in the area of at least one of the first,
second, third, and fourth feeds.
69. Sampling system according to claim 68, further comprising at
least one first discharge from at least one of the first, second,
third, and fourth gas sensor arrays.
70. Sampling system according to claim 69, wherein at least one
valve is arranged at the inlet or in the area of the discharge.
71. Sampling system according to claim 68, further comprising at
least one filter disposed in front of at least one gas sensor
arrays.
72. Sampling system according to claim 71, wherein at least one of
the gas sensor arrays comprises a measuring surface and the at
least one filter is disposed in front of the measuring surface.
73. Sampling system according to claim 72, wherein the at least one
filter is disposed at an inlet of at least one of the first,
second, third, and fourth feeds.
74. Sampling system according to claim 68, wherein the at least one
valve is controllable.
75. Sampling system according to claim 68, further comprising at
least one pump unit in combination with at least one of the first,
second, third, and fourth feeds for the transport of atmosphere to
at least one of the gas sensor arrays to be analyzed.
76. Sampling system according to claim 68, wherein at least one of
the gas sensor arrays comprises several fields made of a
semiconducting metal oxide film, each of which is connected to two
electrodes, whereby the fields form an essentially continuous
surface, the electrodes have a band-like shape and the continuous
surface is divided into fields in such a way that each field in the
continuous surface is delineated by two electrodes.
77. Sampling system according to claim 76, wherein each of the gas
sensor arrays comprises at least two different sensors, different
sensor segments, or different fields that exhibit different
conductivity changes as a function of at least one of temperature,
composition, doping, and coating, upon contact with reducing or
oxidizing gases.
78. Sampling system according to claim 77, wherein the temperature
of at least one of each sensor, sensor segment, and field of each
gas sensor array is adjustable.
79. Sampling system according to claim 78, wherein a specific
temperature gradient or a specific temperature profile is applied
to each gas sensor array.
80. Sampling system according to claim 77, wherein at least one of
each sensor, each sensor segment, and each field is in working
connection with at least one of a thermocouple and a heating
element.
81. Sampling system according to claim 80, wherein at least one of
the thermocouple and the heating element are controllable.
82. Method for the cooking of cooking product with a cooking
appliance according to claim 40, comprising the steps of:
introducing at least the cooking compartment atmosphere to a gas
sensor array, the gas sensor array comprising: at least two
separate, different individual sensors, and at least one coherent
sensor field with at least two different sensor segments; detecting
at least the cooking compartment atmosphere at intervals or
continuously during cooking; comparing an analysis result from the
evaluation unit to a standard stored in the memory unit; and
conducting a cooking process depending on the analysis result.
83. Method according to claim 82, wherein the analysis results
deviate from a selected standard only within a predetermined
bandwidth.
84. Method according to claim 82, wherein the analysis results do
not deviate from a selected standard.
85. Method according to claim 82, comprising varying at least one
of the temperature of the sensor, the temperature of the sensor
segment, the temperature of the field, and the standard used for
the comparison.
86. Method according to claim 85, comprising varying at least one
of the temperature of the sensor, the temperature of the sensor
segment, the temperature of the field, and the standard used for
the comparison before or during the cooking process.
87. Method according to claim 82, comprising storing the standards
during a learning phase in the form of profiles or patterns of the
detected signals of each gas sensor array.
88. Method according to claim 87, comprising storing standards as a
function of at least one of the type of cooking product, an amount
of cooking product, cooking product quality, and a desired degree
of cooking.
89. Method according to claim 88, comprising storing standards for
different temperatures of at least one of each sensor, each sensor
segment, and each field.
90. Method according to claim 82, further comprising the steps of:
introducing a cooking product into the cooking compartment of the
cooking appliance; and determining at least one of the nature and
the initial state of the cooking product with the at least one gas
sensor array after introducing the cooking product into the cooking
compartment.
91. Method according to claim 90, comprising introducing the
cooking product into the cooking compartment during a first heating
phase.
92. Method according to claim 90, comprising considering at least
one of the determined nature and determined initial state during
the control of the cooking process.
93. Method according to claim 90, further comprising at least one
of stopping and providing a warning signal if the initial state of
a cooking product is qualified as spoiled.
94. Method according to claim 82, comprising assigning a cooking
program to each standard during a learning phase.
95. Method for cleaning a cooking appliance according to claim 40,
comprising the steps of: determining the degree of contamination of
the cooking compartment by the at least one gas sensor array after
completion of a cooking process; determining a corresponding
cleaning program corresponding to the degree of contamination with
the evaluation unit; and performing a cleaning program with the
control unit.
96. Method according to claim 95, wherein detecting the degree of
contamination comprises comparing the signals from the at least one
gas sensor array with standards.
97. Method according to claim 96, wherein the standards comprise at
least one of profiles and patterns of the signals of each gas
sensor array.
98. Method according to claim 97, comprising storing the standards
during a learning phase.
Description
[0001] The present invention concerns a cooking appliance with at
least one gas sensor array and a sampling system for a cooking
appliance with at least one gas sensor array. Furthermore, the
invention concerns a method for cooking with the cooking appliance
according to the invention, as well as a method for cleaning the
same.
[0002] The ability to track the cooking process of cooking products
exactly, for example in order to determine the desired final
cooking state and to remove the cooking product from the cooking
appliance in time, is of great importance especially for large
kitchens and canteen operations. Namely, if the desired final
cooking state is not realized, frequently the cooking product has
defective taste, for example a degree of browning that is too
strong, and in the extreme case it has to be discarded completely.
In the case of large cooking product loads, as is customary in
large kitchens, the economic damage is not insignificant. A
frequent cause is that the cooking processes cannot be standardized
completely, which again can be attributed to the non-uniform size
of cooking products, different initial cooking states and the
rarely completely uniform total amount of cooking products to be
cooked.
[0003] In order to achieve reproducible cooking results
nevertheless, independently of the type, size and number of the
cooking products used, so-called cooking process sensors are used
increasingly, for example, in the form of core temperature sensors.
Such cooking process sensors are described, for example, in DE 202
04 393 U1, DE 299 23 215 U1 or DE 199 45 021. With the aid of these
core temperature sensors, using predetermined guide values, one can
determine when a cooking product has reached the desired
predetermined target cooking temperature in its core during a
cooking process. For this purpose, it is generally required that
the core temperature sensor is inserted mechanically into the
cooking product in such a way that it actually reaches to the
center of same. Naturally, in this type of measurement the cooking
product is partially destroyed by the insertion process.
Frequently, even after the end of the cooking process, the
insertion point can be recognized on the surface of the cooking
product. Since the core temperature sensor is often located in the
inner cooking compartment during the entire cooking process,
sometimes injury to the operating personnel occurs due to
inattention. Also, the insertion of the cooking process sensor
during the cooking process is not always optimal, so that, for
example, the cooking process sensor is inserted at a distance from
the actual center of the cooking product. Furthermore, it may occur
that the core temperature sensor cannot be placed at all into the
cooking product because of its small cross-section. Also, the core
temperature is not necessarily representative of the state of
cooking, that is, a correlation between the core temperature and
the state of cooking is possible only with accurate knowledge of
the cooking product.
[0004] At the present time, an attempt is also being made to
determine the state of cooking of foods with the aid of gas
sensors. In any case, these efforts at the present time have not
gone beyond the project stage. For example, in the project
supported by the Federal Ministry for Education and Research of the
Federal Republic of Germany "Sensor system for the control of
frying, baking and roasting processes with the aid of primary aroma
standards" it is supposed to be determined if, with the aid of
suitable gas sensors, the time endpoint of cooking can be
determined during the cooking of foods with the aid of the odor of
the finished food. Within the framework of the above project,
furthermore, the process of roasting of coffee as well as the
product control of foods with the aid of gas sensors was
investigated (see also www.mst-innovationen.de, Infoborsc,
Mikrosystemtechnik, 43-2003, L. Heinert, N. Telde, "Use of
semiconductor gas sensors for the recognition of roasting, frying
and baking processes in the food industry (SPAN)").
[0005] In the method named above, use is made of the fact that when
foods are heated numerous volatile substances are liberated, but
normally only a few of these contribute to their characteristic
odor. For example, the odor of butter is composed of a total of 230
volatile substances, but only a total of 19 of these can be
described as contributing to the odor (L. M. Nijssen et al.,
Volatile Compound in Food, 7.sup.th Edition, TNO Nutrition and Food
Research Institute, Zeist, The Netherlands). Such odorants can be
detected with the aid of metal oxide gas sensors, for example based
on tin dioxide or zinc oxide (see also T. Hofmann et al., "High
resolution gas chromatography/selective odorant measurement by
multisensor array (HRGC/SOMSA): a useful approach to standardize
multisensor arrays for use in the detection of key food odorants",
Sensors and Actuators B 41 (1997), pages 8 to 87). The method
described above is based on the use of so-called chemical leads.
The characteristic components or basic structures responsible for
the odor are recognized here by the gas sensors used in order to be
able to derive the desired conclusions from the detected signals.
This requires, at least in the beginning, the parallel use of an HR
gas chromatograph. As soon as the basic structure signal determined
with the gas chromatography can be assigned to the corresponding
signal of the gas sensor, the use of the gas chromatograph can be
omitted.
[0006] As described by Lemme in Elektronik/17 2002, pages 42 to 48,
when using a gas sensor array called KAMINA of the Karlsruhe
Research Center, the prior determination of guide components is
eliminated. Rather, the patterns detected with this gas sensor are
simply compared to one another. Located above a frying pan that is
filled with steaks, the above KAMINA sensor array, after an initial
learning phase, should be able to determine the various states of
frying from ""raw" through medium" and "well done" to "overdone."
The heating of the frying pan should shut off automatically exactly
at the desired moment with the aid of the said sensor array.
Information on further suitability of the described sensor array
for the determination of states of cooking are not described in the
quoted literature citation or in the German Patent Application DE
44 23 289 C1 based on the above gas sensor. It is already
questionable if the possibilities of use of this type of sensor can
be extended to completely different types of situations. For
example, the cooking atmosphere in the internal compartment of
especially industrial cooking appliances is not comparable to the
atmosphere existing above an open frying pan. This applies even
more to the so-called convection cooking appliances in which
regularly a rapidly-rotating fan is used. Also, the moisture
content in such appliances is usually very high and is not
infrequently in the saturation range. So far, in such hot air
convection steam appliances the cooking process could be controlled
somewhat satisfactorily only with the aid of core temperature
sensors. Accordingly, the gas sensors that are used in cooking
appliances in U.S. Pat. No. 6,784,404 and US 2004/0144768 A1 are
used exclusively for the determination of the carbon monoxide
content, with the purpose of being able to establish the duration
of the cleaning cycle of a self-cleaning cooking appliance by
determination of the degree of contamination of the cooking
compartment.
[0007] It would therefore be desirable, especially also due to the
inadequacies observed when using core temperature sensors, to have
a means for monitoring the cooking process that yields
reproducible, reliable results, without having to specify
previously the cooking product, for example regarding size or
initial cooking state.
[0008] For example, a multifunctional sensor is known from U.S.
Pat. No. 4,378,691 which comprises a single sensor element which is
heated by a heating element. This sensor element can be used to
control a cooking appliance as a function of the moisture content
in a cooking compartment.
[0009] In DE 103 07 247 A1, a vapor ventilation hood of an electric
oven with a waste air tube is disclosed which has a number of
sensors that are designed for the evaluation of gaseous media or
substances in the gaseous media. Based on the data detected and
evaluated through the sensor, a fan in the exhaust tube of the
electric oven can, for example, be controlled. Similarly, according
to DE 103 07 247 A1, based on the measured data, the power of the
electric oven can be controlled.
[0010] U.S. Pat. No. 6,170,318 B1 discloses a generic cooking
appliance as well as generic sampling system using a gas sensor
array with a number of gas sensors, which is supposed to be able to
detect various substances after a learning phase. For example, such
a gas sensor array can be used in a microwave appliance or a
roasting appliance in order to control the corresponding cooking
appliance based on the measured data or to determine if a cooking
product is still fresh.
[0011] Therefore, the task of the present invention is to further
develop the generic cooking appliance or the generic sampling
system in such a way that the disadvantages of the state of the art
are overcome. Especially, a contactless control of a state of
cooking should be permitted independently of external disturbing
influences, above all also for larger cooking product loads in the
internal chamber of a cooking appliance and greater process
reliability should be provided.
[0012] The task concerning the cooking appliance is solved by the
characteristics of Claim 1.
[0013] Advantageous embodiments of the cooking appliance according
to the invention are described in Claims 2 to 20.
[0014] Fundamentally, all cooking appliances that have an inner
cooking compartment and an installation compartment come into
consideration as starting point for the cooking appliances
according to the invention. Especially preferred are those cooking
appliances that are further equipped with at least one aeration
system, that is, so-called hot air convection steamers. Suitable
hot air convection steamers which form the starting basis of the
cooking appliances according to the invention, are described, for
example, in DE 196 515 14 A1. The fan wheels used in conventional
hot air convection steamers operating at high velocities sometimes
produce very high air velocities in the inner cooking compartment,
as a result of which sometimes fat and other liquid droplets are
swirled in the inner cooking compartment.
[0015] Naturally, a memory and evaluation unit as well as a control
system of a cooking appliance according to the invention can be
present in a single processor. With the aid the control system, for
example, the heating of the cooking compartment, the speed of the
fan, the steam generator, the aeration, for example with fresh air,
the misting nozzle and/or the cleaning nozzle can be
controlled.
[0016] A cooking appliance according to the invention, comprising
at least one gas sensor array, permits the monitoring of the gas
atmosphere in and at the cooking appliance and thus can orient
itself both with respect to guide structures, the signal of which
was previously determined and entered into the memory unit of the
cooking appliance, as well as preferably with regard to the
entirety of the detected signal. In the latter case, the desired
information is determined without the use of a guide structure,
based on the change of the complex signal pattern over time during
the cooking process, for example, in order to be able to draw
conclusions about the state of cooking. That is, a number of
signals originating from volatile, especially oxidizable and/or
reducible substances, are regularly recorded with the gas sensor
arrays. Signals of certain individual compounds cannot be extracted
from these total spectra. Generally, this is also not required due
to the detection of the total patterns by the sensor a ray. At
least two, especially a multiple number of individual sensors or
sensor segments of a gas sensor array yield a different measured
signal under essentially identical conditions and for an
essentially identical atmosphere to be measured. In this way, a
characteristic total measurement result is obtained for each
specific situation or atmosphere to be measured. Frequently, even 5
to 100, for example also 10 to 50 individual sensors or sensor
segments, are sufficient for the recording of signal patterns with
sufficient information about a time period.
[0017] In order to be able to draw a conclusion about a state of
cooking, generally first of all a so-called learning phase is
required. The states to be determined in the cooking appliance,
especially the cooking states, will hereby be first run
experimentally and the time development of the detected signal
pattern for an optimum cooking process as normal state is
determined and stored. Then the time courses of the signal patterns
for cooking processes that deviate from this optimum state are
determined and stored. Accordingly, if in a cooking process the
time change of the detected signals remains within the desired
limits or tolerances, the intended desired cooking process control
is being maintained. Otherwise, alternative solutions are used.
Thus, it is of particular importance to follow the time development
or time change of the entirety of the detected signals. In general,
it is sufficient to perform the above learning phase for a certain
cooking appliance type only once. The obtained signal patterns can
then easily be used for all other cooking appliances and for
example can be entered into their memory unit.
[0018] It was found to be especially advantageous when at least one
gas sensor array is introduced into the inner cooking compartment,
in the installation compartment, in the aeration system and/or
outside the cooking appliance.
[0019] Also preferably the gas sensor array has several fields made
of a semiconducting metal oxide film, each of which are connected
to two electrodes, whereby the fields form an essentially
continuous flat surface, the electrodes have a band-shaped form and
the continuous surface is divided into fields in such a way that
each field in the continuous surface is delineated by two
electrodes in each case.
[0020] Correspondingly, suitable gas sensor arrays may comprise an
arrangement of several, for example eight, individual sensors,
which are arranged pairwise on a silicon chip. Each of these
individual sensors consists of one or several of the semiconducting
oxides SnO.sub.2, ZnO, TiO.sub.2, WO.sub.3 and is applied as a thin
film on the chip, which is covered at least partially with
palladium or platinum as catalyst. All the individual sensors used
differ in their composition or in their structure. Upon contact
with the gases measured, the conductivity of the semiconducting
oxides changes as a function of their composition and of the
catalytic palladium coating that is optionally applied on them;
therefore, each individual sensor in contact with a gas to be
measured provides a different signal, which is proportional to the
change of the conductivity. Such a gas sensor array is described,
for example, in X. Wang et al., Sensors and Actuators B 13-14
(1993) 458-461.
[0021] Especially preferred for use are those gas sensor arrays in
which different fields, comprising semiconducting metal oxide thin
films, each of which is connected to two electrodes, will show
different changes in conductivity upon contact with reducing or
oxidizing gases as a function of the temperature, composition,
dosage and/or coating.
[0022] The sensitive layer of a preferred gas sensor array is
composed especially of a single continuous layer of one or several
semiconducting oxides, for example tin dioxide, whereby this
continuous layer is subdivided into individual fields by
band-shaped electrodes. The electrodes can be applied directly to
or below the surface of the continuous layer. The continuous
surface is divided into the above fields especially in such a way
that each field in the continuous surface is delineated preferably
by two electrodes. According to one advantageous embodiment, the
gas sensor array is provided with a coating, the permeability of
which for reducing or oxidizing gases changes continuously between
the two outer electrodes.
[0023] Especially in the analysis of complex gas systems, it is
advantageous when the individual fields of the sensor array differ
from one another in their structure or in their composition. Each
field then will provide a different change in conductivity in
comparison to the other fields, when the sensor is brought into
contact with a single gas. A different composition of the fields
can be achieved, for example, by evaporation of noble metals, that
is, a doping of the metal oxide film over time periods of different
lengths. A continuous change of the composition along the
continuous surface of the gas sensor array can be achieved with the
aid of chemical vapor deposition.
[0024] It can also be of advantage to adjust the sensitivity of a
gas sensor array for certain gases by application of certain
temperatures, especially by application of different temperatures
to the different fields. For this purpose it should be mentioned
first of all that the sensitivity of a gas sensor array is
fundamentally high when: [0025] a strong change in the signal of
the gas sensor array, for example in the resistance of an
individual sensor, can be recognized as a function of the time of a
progressing chemical reaction; [0026] a signal of the gas sensor
array is strong in itself, that is, a defined concentration
produces as strong a signal as possible; [0027] different,
simultaneously-produced gases produce signal patterns in the gas
sensor array that are as different as possible, or [0028] the
detection limit of a gas is so low that the identification of the
gas can be done even at low concentrations.
[0029] It has been found that one and the same sensor of a gas
sensor array has opposite sensitivities for different gases
depending on the temperature, as a result of which the temperature
of each sensor should be adjustable advantageously. For this
purpose, the temperature of each field of the gas sensor array
should be determined, for example, using a thermocouple, and each
field then can be heated in a designed manner, for example with the
aid of a heating wire.
[0030] Especially suitable gas sensor arrays are described, for
example, in DE 44 23 289 C1 and are also known as the so-called
Kamina sensors of the Karlsruhe Research Center.
[0031] According to a further aspect of the present invention, the
cooking appliances according to the invention are also
characterized by at least one second feed for the atmosphere from
the installation compartment to at least one first, second, third
and/or fourth gas sensor array, at least one third feed for the
atmosphere from the aeration system to at least one first, second,
third and/or fourth gas sensor array and/or at least one fourth
feed for the atmosphere surrounding the cooking appliance to at
least one first, second, third and/or fourth gas sensor array.
[0032] Furthermore, suitable cooking appliances are equipped with
at least one first discharge from the first, second, third and/or
fourth gas sensor array.
[0033] In order to protect the measuring surface of the gas sensor
array against permanent contamination, it was found to be
advantageous to install at least one filter in front of at least
one gas sensor array, especially in front of its measuring surface,
and/or to install it at the inlet to the first, second, third
and/or fourth feed. Suitable filters are, for example, plastic
membranes, for example made of Teflon, ceramic filters, for example
a porous aluminum oxide ceramic, or metallic filters, for example a
porous metal foam. Sintered metal filters are especially
suitable.
[0034] Furthermore, the cooking appliances according to the
invention are characterized by at least one valve that can be
controlled with the control unit, at the inlet and/or in the area
of the second, third and/or fourth feed and/or the discharge.
[0035] With the aid of the above valves, especially in the course
of the discharge, for example the entry of waste air into the gas
sensor array, can be prevented. The feeds to the gas sensor arrays
are preferably designed to be very short in order not to
unnecessarily delay or spread the detected signal.
[0036] Suitable cooking appliances comprise in another embodiment
in addition at least one pump unit in working connection with a
first, second third and/or fourth line for the transportation of
the atmosphere to be analyzed to the gas sensor array(s). For
example, with the aid of a pump, the atmosphere from the cooking
compartment or the installation compartment or even outside air can
be introduced to the gas sensor array through a filter that does
not change the characteristic composition of the sample volume. In
this case, the filter may retain for example solid particles as
well as fat and liquid droplets.
[0037] According to the invention it is also provided that at least
two feeds are connected directly or indirectly to the gas sensor
array.
[0038] For example, at least one sensor array is integrated in the
inner wall of the inner cooking compartment or the installation
compartment. Naturally, in order to determine or analyze the
atmosphere in the area outside the cooking appliance, the gas
sensor array may also be present on the outer wall of the cooking
appliance or can be integrated into this wall. Furthermore,
according to another embodiment, the gas sensor arrays arranged in
the inner wall or outer wall of the cooking appliance can also have
feeds for the purpose of introduction of the atmosphere to be
analyzed. This is especially advantageous when the gas sensor array
does not lie on the wall surface but is integrated into it. These
feeds can also be used to introduce suitable filters in front of
the gas sensor array.
[0039] Preferably at least two inner walls of the inner cooking
compartment are equipped with a gas sensor array. In this way, the
cooking progress can be detected depending on the location.
[0040] The task concerning the sampling system is solved by a
sampling system for a cooking appliance comprising at least one
first gas sensor array for detection of the atmosphere from a
cooking compartment of the cooking appliance, a second gas sensor
array for the detection of the atmosphere from an installation
compartment of the cooking appliance, a third gas sensor array for
the detection of the atmosphere from an aeration system of the
cooking appliance and/or a fourth gas sensor array for the
detection of the atmosphere surrounding the cooking appliance and
at least one feed for the atmosphere from the cooking compartment
to the first, second, third and/or fourth gas sensor array, at
least one second feed for the atmosphere from the installation
compartment to the first, second, third and/or fourth gas sensor
array, at least one third feed for the atmosphere from the aeration
system to the first, second, third and/or fourth gas sensor array,
and/or at least one fourth feed for the atmosphere surrounding the
cooking appliance to the first, second, third and/or fourth gas
sensor array, whereby at least one valve is arranged at the inlet
and/or in the area of the first, second, third and/or fourth
feed.
[0041] Hereby at least one discharge from the first, second, third
and/or fourth gas sensor array can be provided, whereby preferably
at least one valve is arranged at the inlet and/or in the area of
the discharge.
[0042] With the invention, it is also proposed that at least one
filter be arranged in front of at least one gas sensor array,
especially in front of its measuring surface and/or in or on the
inlet of the first, second, third and/or fourth feed.
[0043] Furthermore, it can be provided that at least one valve is
controllable.
[0044] With the invention it is also proposed that at least one
pump unit be arranged in combination with the first, second, third
and/or fourth feed for the transportation of the atmosphere to be
analyzed to the gas sensor arrays.
[0045] Preferred sampling systems according to the invention are
characterized by the fact that the gas sensor array comprises
several fields consisting of semiconducting metal oxide film, each
of which is connected to two electrodes, whereby the fields form an
essentially continuous surface, the electrodes have a band-like
shape and the continuous surface is divided into fields in such a
way that each field is delineated in the continuous area by two
electrodes.
[0046] According to the invention it is also proposed that
different sensors, sensor segments and/or fields of each gas sensor
array exhibit different conductivity changes as a function of
temperature, composition, doping and/or coating when they come into
contact with reducing or oxidizing gases.
[0047] Furthermore, it can be provided that the temperature of each
sensor, sensor segment and/or field of the gas sensor a ray be
adjustable, preferably that a specific temperature or a specific
temperature profile can be applied to the gas sensor array.
[0048] With the invention it is also proposed that each sensor,
each sensor segment and/or each field be in working connection with
a preferably controllable thermocouple and/or heating element.
[0049] Moreover, according to a further aspect, a method for the
cooking of cooking product with a cooking appliance according to
the invention is proposed in which at least the cooking compartment
atmosphere is introduced to a sensor, sensor segment or field of at
least one gas sensor array and is detected at intervals or
continuously during the cooking, the analysis result is compared in
the evaluation unit with a standard stored in memory unit and the
cooking process is conducted as a function of the analysis
result.
[0050] Hereby it can be provided that the analysis results do not
deviate from a selected standard or deviate only within a
predetermined band width.
[0051] Furthermore, it can be provided that the temperature of the
sensor, sensor segment or field and/or of the standard used for
comparison is/are varied, especially before or during the cooking
process.
[0052] Furthermore, it is proposed according to the invention that
standards be stored in a learning phase in the form of profiles or
patterns of detected signals of each gas sensor array, especially
as a function of the type of cooking product, amount of cooking
product, cooking product quality and/or the desired degree of
cooking, preferably for different temperatures of each sensor,
sensor segment and/or field.
[0053] It can also be provided that, after introduction of the
cooking product into the internal compartment of the cooking
appliance, especially during a first heating phase, the nature
and/or initial state of the cooking product be determined,
especially during a first heating phase, through the use of the gas
sensor array(s).
[0054] Hereby it is proposed that the determined nature and/or the
determined initial state can be taken into consideration during the
control of the cooking process.
[0055] Furthermore it is proposed with the invention that when the
initial state of a cooking product is qualified as spoiled, the
cooking process be stopped and/or a warning signal be emitted.
[0056] Furthermore, it can be provided that a cooking program is
assigned to each standard in a learning phase.
[0057] Thus, it is especially advantageous when, during learning,
different temperature profiles are applied to a gas sensor array,
the signals of the gas sensor a ray are stored and a cooking
program is assigned to each signal pattern of the gas sensor array,
which forms a standard. In normal operation of the cooking
appliance according to the invention, then information from a
control panel of it and from the gas sensor array are used to
classify chemical processes which occur in the cooking compartment
by comparison with the said standards. As soon as a classification
has occurred, then one can use a suitable experimentally determined
temperature profile which optimizes the sensitivity of the gas
sensor array and makes the selection of an optimum cooking program
possible. With the aid of a multiple number of thermocouples and
heating elements, the temperature profile of the gas sensor array
can be adjusted at any time, also many times during a cooking
process, namely when a classification is to be adapted.
[0058] For example, if according to an input through the control
panel of a cooking appliance in a time-controlled cooking program,
only the moisture content in the cooking compartment is to be
controlled, then, according to the invention, the temperature
profile is selected automatically from a multiple number of stored
temperature profiles with which the H.sub.2O content of the cooking
atmosphere can be determined as accurately as possible, while
larger hydrocarbons, which are themselves caused by the cooking of
the cooking product, should contribute as little as possible to the
signal.
[0059] On the other hand, if it is entered through the control
pattern that the meat is to be roasted, and one can recognize from
the profile or pattern of the gas sensor array that, with high
probability, the meat is beef, then the control device of the
cooking appliance according to the invention will select
automatically a temperature that has proven itself in its
sensitivity for roast beef. Hereby, larger hydrocarbons that occur
during cooking contribute especially strongly to the formation of
the signal pattern.
[0060] A further aspect provides a cleaning method of a cooking
appliance according to the invention according to which, after the
end of a cooking process, the degree of contamination of the
cooking compartment is determined through the gas sensor array(s),
and through the evaluation in it a cleaning program is selected
that corresponds to the degree of contamination and then this
cleaning program is run by the control unit.
[0061] Hereby it can also be provided that the degree of
contamination is determined by a comparison with standards,
preferably in the form of profiles or patterns of the signals of
each gas sensor array, these profiles having been stored
specifically in a learning phase.
[0062] With the previously outlined embodiments of the cooking
appliance, sampling systems or methods according to the invention,
it is possible to detect odors at various locations in or by the
cooking appliance. This can be done either with the aid of several
gas sensors, optionally equipped with their own feeds for sampling,
which are attached at the measuring locations or with the aid of a
number of feeds, which together serve a central gas sensor
array.
[0063] According to the invention an optimum cooking result is also
obtained when the atmosphere in the inner cooking compartment is
disturbed or altered during the cooking process, for example, by
frequent opening and closing of the door of the cooking
compartment. Upon such changes in the cooking compartment
atmosphere, which are not known to the cooking appliance and/or are
not stored in the memory unit, an error message can be produced for
the operating personnel. Furthermore, it is of advantage that
through the detected odor pattern during the initial heating of the
cooking product, its initial state, for example frozen, marinated,
etc., can be determined. If it is determined with the aid of the
time development of the detected total pattern, that, for example,
we are dealing with a frozen product, first a thawing or heating
phase can be initiated by the control. If marinated product is
detected, one can ensure that this is not overheated. Also, in this
early stage of the cooking process, it can also be determined if
the food to be cooked is possibly already spoiled and/or if poorly
aged meat should possibly be exposed to a holding phase in order to
obtain the desired cooking result nevertheless.
[0064] Thus, it is an advantage that the initial state of the
cooking product, for example of the meat, no longer has to be
determined by the user visually or haptically but can be determined
with the aid of the cooking appliance according to the
invention.
[0065] Since the speed with which the known or stored signal
courses change also depends on the amount of the cooking products
introduced into the inner cooking compartment, already in the
initial phase of the cooking product a so-called load recognition
can be performed with the cooking appliances according to the
invention. Then the cooking program can be adjusted individually to
the determined load.
[0066] The determination of odorant compounds can also be used in
order to detect the surface state as well as the cooking of the
particular cooking product. For example, if a cooking product is
already sufficiently browned, but cooking is not yet complete, the
cooking compartment temperature must be reduced correspondingly so
that the browning will not become too strong. From the detectable
rate of the surface reaction and the rate of cooking, furthermore,
one can also determine the size of the cooking product.
Furthermore, it is of advantage that processes, such as flavoring,
moistening or basting of the cooking products no longer have to
occur as a function of time but as a function of the actual cooking
state, always at the correct point in time. This process can of
course also be automated with the aid of the cooking appliances
according to the invention.
[0067] Since the sampling at several locations in the cooking
internal compartment can be performed simultaneously or almost
simultaneously, the operating personnel using the cooking
appliances according to the invention are easily informed as to
whether the cooking products being cooked uniformly or if there are
areas with more highly cooked or less highly cooked cooking
product. Using deflectable or adjustable deflectors, for example,
the cooking products that have been cooked less can be provided
with energy in a hot air convection steamer in a targeted
manner.
[0068] With the aid of the gas sensor arrays used in the cooking
appliance according to the invention, after the end of the cooking
process, the degree of contamination of the cooking compartment can
be determined. For example, a simple comparison of stored initial
state and end state can be used for this. With the aid of this
degree of contamination, a cleaning program can be proposed or
carried out by the cooking appliance automatically, adjusted to
this degree of contamination. For example, if a high fat content is
detected, automatically a corresponding amount of emulsifier can be
proposed or used. Similarly, when a protein-containing
contamination is detected, a cleaning agent containing enzymes can
be proposed.
[0069] Moreover, with the cooking appliance according to the
invention, erroneous operations as well as disturbances, for
example smoldering odors, overheating or leakage of the cooking
system into the installation compartment as well as the cooking
compartment can be immediately detected. It has been found to be
especially advantageous that the initial state of cooking and the
final state of cooking can generally be determined and compared to
one another, which gives an indication whether or not all desired
hygienic prerequisites have been observed.
[0070] For example, if a steam generator is used in a cooking
appliance, with the aid of the gas sensor array present in the
cooking appliance according to the invention, the quality of the
water can also be determined directly.
[0071] Reliable data recording is provided especially through the
combined use of at least one pump, at least one filter and at least
one valve.
[0072] Other characteristics and advantages of the invention follow
from the specification given blow in which practical examples of a
cooking appliance according to the invention are explained in
detail with the aid of schematic drawings. The following are
shown:
[0073] FIG. 1 is a schematic cross-sectional representation of a
cooking appliance according to the invention;
[0074] FIG. 2 is a schematic cross-section of an alternative
embodiment of a cooking appliance according to the invention;
and
[0075] FIG. 3 is a representation of a gas sensor array in
combination with essential components of a cooking appliance
according to the invention.
[0076] FIG. 1 is a cooking appliance according to the invention in
the form of a hot air convection steamer 100, comprising a cooking
compartment 1 with a cooking compartment door 8 and a drain 10, an
aeration system 7 as well as an installation compartment 9. In this
embodiment, a gas sensor array 2 is located in the installation
compartment 9. A gas sample to be analyzed from the cooking
compartment 1, aeration system 7, installation compartment 9 or at
the atmosphere 11 outside the cooking appliance 100 can be
introduced to the gas sensor array 2 through lines 20, 22, 24 and
26, separately or simultaneously. The sampling can be completed
easily with the aid of controllable valves 4 as well as a pump 3,
which is connected after the gas sensor array 2. It has been found
to be advantageous to equip the feeds 20, 22, 24, 26 with suitable
filters 5 or 6. For example, for the measurement of the atmosphere
in cooking compartment 1, it can be provided that, except for the
valve 4 in feed 20, all other valves 4 are closed, so that only the
desired cooking compartment atmosphere is introduced to the gas
sensor array 2.
[0077] Alternatively, as shown in FIG. 2, each sampling system can
be equipped with its own gas sensor array 2. In this variation, the
atmosphere can be introduced to the particular gas sensor array 2
from the cooking compartment 1 through feed 20, from the aeration
system 7 through feed 22, from the installation compartment 9
through line 24 and atmosphere 11 from outside the cooking
compartment 100 through line 26. As already explained in connection
with FIG. 1, the variation shown in FIG. 2 is also operated with
filters 5 and 6, in the area of the inlets to feeds 20, 22, 24 and
26. With the aid of separately controllable pumps 3, the
introduction of the sample can be controlled for each gas sensor
array 2.
[0078] As can be seen from the embodiments of FIGS. 1 and 2, gas
samples can be taken simply at different locations in or on the
cooking appliance 100, and can be introduced either to a central
gas sensor array 2 or separately to several ones of these. Since
the samples can be introduced from the internal compartment as well
as the outside of the cooking equipment 100 to the gas sensor
array(s) 2 and measured, perturbations by environmental influences
in the determination of the optimum cooking process can, for
example, be avoided.
[0079] As can be seen in FIG. 3, a gas sensor array 2, as can be
used in a cooking appliance 100 according to FIG. 1 or FIG. 2, can
have a number of fields each of which serves to detect a gas
whereby the sensitivity to a specific gas can be adjusted through a
temperature profile which is applied specially in each case. The
temperature profile can in this way be selected or adjusted
depending on the type of cooking product, such as beef, pork, fish
or poultry, according to a degree of cooking, determined by the
core temperature and/or the browning, or similar, for example
through a control panel 101 of the cooking appliance 100, and
namely preferably with the connection of a control or regulation
device 102 of the cooking appliance 100 in between. An adjustment
control of the temperature profile 200 is then also possible
depending on the output data of the gas sensor array 2 itself.
Thus, during a cooking process, one can optimize the sensitivity
and thus optimize the assignment of a cooking process to a standard
cooking process and finally arrive at a special cooking program,
which in the end ensures that one obtains reproducible, good
cooking results.
[0080] The characteristics of the invention disclosed in the above
specification, in the drawings as well as in the claims can be
essential both individually as well as in any arbitrary combination
for the realization of the invention in its various
embodiments.
REFERENCE LIST
[0081] 1 Cooking compartment [0082] 2 Gas sensor array [0083] 3
Pump [0084] 4 Valve [0085] 5 Filter [0086] 6 Filter [0087] 7
Aeration system [0088] 8 Cooking compartment door [0089] 9
Installation compartment [0090] 10 Drain [0091] 11 Atmosphere
[0092] 12 Discharge [0093] 20 Feed [0094] 22 Feed [0095] 24 Feed
[0096] 26 Feed [0097] 100 Cooking appliance, hot air convection
steamer [0098] 101 Control panel [0099] 102 Control or regulation
device [0100] 200 Temperature profile
* * * * *
References