WO2015018890A1

WO2015018890A1 - Cooking device and method for operating a cooking device

Info

Publication number: WO2015018890A1
Application number: PCT/EP2014/066985
Authority: WO
Inventors: Volker Backherms; Dominic Beier; Bastian Michl
Original assignee: Miele & Cie. Kg
Priority date: 2013-08-09
Filing date: 2014-08-07
Publication date: 2015-02-12
Also published as: DE102013108647A1

Abstract

The method according to the invention is suitable for operating a cooking device with a cooking hob and a heating device for heating a cooking area. A measurement system comprising a sensor device for detecting a first characteristic variable for temperatures of the cooking area is provided. According to the invention, a parameter is determined. The parameter describes a dynamic property of the measurement system and is taken into consideration for determining the temperature of the cooking area.

Description

description

"Cooking device and method for operating the cooking device"

The present invention relates to a cooking device with at least one measuring system and a method for operating a cooking device.

In the prior art cooking appliances have become known that offer automatic functions. A prerequisite for such an automatic operation of a cooking device is sometimes a detection of various parameters that are characteristic of the cooking process, such. B. the temperature of the food container and in particular the pot bottom. Depending on the detected parameters then the automatic function and in particular the heating power of the cooking device are controlled. The heat source must be controlled so that z. B. an undesirable overheating of the food is avoided. Therefore, the reliability or accuracy of the detected parameters is crucial to the functionality of the automatic function.

In the prior art, for example, devices have become known for determining temperatures during cooking and cooking processes, which determine the temperature on the underside of a food container without contact. This is how z. B. the WO 2008/148 529 A1 a heat sensor below a hob plate before, which detects the radiated heat radiation and determines the temperature of the Gargutbehälters or the pot bottom.

The known devices and methods are suitable for use

Automatic functions of cooking appliances, such. As a stove, but still capable of improvement. For example, an automatic boil-up of milk without overcooking the milk places very high demands on the corresponding devices and processes with regard to reproducibility and reliability. An important aspect for a reliable determination of the pot temperature from the detected heat radiation power is z. B. the delimitation of the usable signals from interfering background signals.

It is therefore the object of the present invention to provide a method and a cooking device which improve the reproducibility of temperature determinations in cooking operations.

This object is achieved by a method having the features of claim 1 and a cooking device having the features of claim 13. Preferred features are the subject of the dependent claims. Further advantages and features emerge from the general

Description of the invention and the description of the embodiments. The inventive method is suitable for operating a cooking device with at least one hob and at least one heating device for heating at least one cooking area. At least one measuring system with at least one sensor device is provided for detecting at least one first characteristic variable for temperatures of the cooking area and in particular of a cooking vessel set up in the cooking area. At least one parameter is determined. The parameter describes at least one dynamic property of the measuring system and becomes the

Determination of the temperature of the cooking area considered.

The method according to the invention has many advantages. A significant advantage is that at least one parameter is taken into account, which is at least one dynamic property of the

Measuring system describes. Dynamic properties of the measuring system are in particular properties which change in at least one period and preferably in shorter periods. The period is compared with periods in which z. B. can change static parameters, rather short. Therefore, in particular, a description of such dynamic properties as a function of time is particularly advantageous.

The dynamic property can be z. B. be described by a parameter which characterizes a change over time of the detected values from the measuring system. Based on the temporal change can then z. B. can be deduced whether the measuring system operates under approximately constant conditions or, for example, is exposed to non-linearly changing conditions. The consideration of such a parameter can be used particularly advantageously in the evaluation of useful signals and the delimitation to interference signals. As a result, the reproducibility in determining the temperature of the cooking area can be significantly improved.

In particular, the parameter describes how at least one property of the

Modified measuring system and preferably changed over time. Preferably, the parameter describes the change over a predetermined period of time. It can also

continuously a new parameter can be determined, for example, in an interval.

It is possible that two or three or more parameters are determined and / or taken into account. The parameters can be taken into account with different weightings. The parameters are different in particular. The parameters can also be similar. Similar parameters are z. B. time derivatives of the same measurand, but take into account different periods of time.

It is also possible that at least one second characteristic variable for temperatures of the cooking region is detected, in particular, by the sensor device. Other characteristic variables for cooking zone temperatures can also be recorded. In this case, at least one parameter can be determined from at least part of the detected characteristic quantities.

Preferably, the heating device comprises at least one induction device. The

Induction device is designed in particular as an induction heating source and comprises at least one induction coil. It is possible that the induction device comprises a plurality or a plurality of smaller induction coils. Then it is possible that the cooking area, for example, results flexibly by placing a Gargutbehälters. It is also possible that fixed hotplates are specified.

The cooking area may also have at least one food container, z. B. a pot or pan, which were parked there. In this case, the temperature of the bottom of the food container in the cooking area is preferably determined.

Preferably, the parameter is determined taking into account a measured variable. The

In this case, the measured variable is in particular a sensory measured variable. The measured variable can be used directly as a parameter. The measured variable can also be calculated and then used as a parameter. For example, can

Heat radiation power can be detected as a measure, the time derivative of the intensity of the heat radiation then serves as a parameter.

The measured variable can be z. Example, a temperature, an electrical voltage or an electrical current or resistance, for example, from the heater or the

Sensor device. It can also be at least one measured variable which is already detected during regular operation of the cooking device, for. B. detected by a safety sensor temperature or the detected by a control device active power or actual power, such as in the form of a performance characteristic of the induction coil. Preferably, the parameter is determined or derived from a temporal change of the measured variable.

Particularly preferably, the parameter is determined taking into account the first characteristic variable detected by the sensor device. However, the parameter can also be determined taking into account another and, in particular, a second characteristic variable detected by the sensor device. It is also possible that the first and also the second characteristic variable are used to determine the parameter.

Also particularly preferably, the parameter is at least one value for the temporal

Changing the first characteristic variable detected by the sensor device and / or the second characteristic variable detected by the sensor device and / or the temperature of at least one region of the sensor device. The temporal change is in particular due to at least one derivation over time and / or an increase and / or a rate of change and / or a regression of a function of the first and / or the second characteristic size and / or the temperature of at least a portion of the sensor device determined. But it is also possible that the parameter is determined by a derivative of the first and / or the second characteristic variable on a different size than the time, such as a characteristic of the heating power.

It is possible that the sensor device detects heat radiation originating at least partially from the cooking area as the first characteristic variable for temperatures of the cooking area. Preferably, the heat radiation is predominantly from the cooking area. The sensor device may for this purpose comprise at least one sensor unit. The sensor unit outputs as output a first size, which is characteristic of the

Thermal radiation performance is, such as the voltage of a thermocouple or a thermopile, which is often referred to as thermopile. In particular, such an output signal is derived over time and taken into account as a parameter.

In particular, the heat radiation detected as the first characteristic quantity originates at least partially, and preferably for the most part, from an im

Cooking area positioned food containers. In this case, the sensor unit preferably has a wavelength-selective filter device.

The sensor device can detect at least one second characteristic variable.

Preferably, at least one further sensor unit is provided for this purpose. The second

Characteristic size is derived in particular over time and taken into account as parameters. The second characteristic variable is in particular heat radiation, which emanates at least to a predominant part from a carrier device. The carrier device is provided in particular for positioning a food container. The carrier device is preferably a glass ceramic plate and / or a so-called ceran field. The further sensor unit can also be designed as a heat sensor, which detects the temperature of the carrier device directly, for. B. as a resistance thermometer.

In a preferred embodiment of the method, the temperature of the cooking region is determined from the first characteristic quantity taking into account the second characteristic variable. It is advantageous that the previously determined temperature of

Carrier device in the determination of the temperature of the Gargutbehälters in the cooking area can be calculated accordingly.

Furthermore, it is preferred that the emission properties of the cooking area for

Heat radiation at least partially taken into account. In particular, the

Emissivity and / or the reflectance of a positioned in the cooking area

Gargutbehälters determined. For this purpose, a calibration method, for example with a Radiation source be provided. Thus, the temperature of the Gargutbehälters can be determined very reliably from the detected heat radiation.

It is also preferred that at least one other parameter be determined and taken into account for determining the temperature of the cooking area. The further parameter preferably describes at least one static property of the measuring system, for example a property of the measuring system at a specific time. In particular, a

Change of properties over time not taken into account, as z. This would be the case, for example, for a parameter which describes the dynamic properties of the measuring system.

Preferably, the further parameter is determined taking into account a measured variable. The measured variable is in particular a sensory measured variable. Particularly preferably, the further parameter or the measured variable describes at least one temperature of at least one region of the sensor device. For example, the sensor device may have at least one integrated sensor element. The temperature detected by the sensor element can be used as a further parameter. It is also possible that a plurality of sensor elements are provided, wherein an average of the signals of the sensor elements is used as a further parameter.

Such a further parameter makes it possible to evaluate the occurrence of unwanted spurious radiation, which arises due to the operating heat of surrounding components or even of the sensor unit itself and radiates into a detection area of the sensor device. Thus, this interference can be taken into account and calculated out accordingly in the temperature determination, whereby the reproducibility of the measurements is further improved.

In particular, the heating device is controlled as a function of the first characteristic variable detected by the sensor device. The heating device can also be controlled as a function of the second characteristic variable. It is also possible that the

Heating device is controlled in dependence of the first and second characteristic size. Preferably, the heating device is controlled as a function of the temperature, which is determined on the basis of the first and the second characteristic variable.

Preferably, the heating device is controlled as a function of the temperature of the cooking area, which is determined taking into account the parameter. The temperature of the cooking area can also be determined taking into account the further parameter. It is also possible to determine the temperature of the cooking area below

Consideration of the parameter and the further parameter. This allows the

Heating device can be controlled particularly reliable, because the control used temperature was determined by the consideration of the parameters accordingly.

The cooking device according to the invention comprises at least one hob and at least one heating device. The heating device is provided for heating at least one cooking area. Furthermore, the cooking device comprises at least one measuring system with at least one sensor device for detecting at least a first characteristic variable for temperatures of the cooking region. It is at least one control device for controlling the heating device as a function of the first detected by the sensor device

characteristic size provided. In this case, the control device is suitable and designed to determine at least one parameter describing at least one dynamic property of the measuring system and to take into account the parameter for determining the temperature of the cooking zone.

The cooking device according to the invention has numerous advantages. Particularly advantageous is the control device which calculates the temperature in the cooking area and thereby takes into account at least one parameter which at least one dynamic property of

Measuring system describes. Due to such a parameter disturbing influences can be detected and taken into account, such. B. the proportion of heat input from outside the object to be determined. As a result, for example, the temperature of a pot on a hob with improved accuracy can be determined.

In a particularly preferred embodiment, the control device is suitable and designed to convert the parameter from the time change of the first detected by the sensor device

characteristic size to be determined. The control device can be arranged separately or integrated, z. B. in the sensor device or the measuring system.

When determining the temperature in the cooking area, the respective values can preferably be calculated by means of linear and / or non-linear equation systems and / or by means of fuzzy logic and / or by means of at least one artificial neural network. The respective values are in particular the first and / or the second characteristic variable and / or the emission properties of the measuring system and in particular the emissivity of the food container and / or the at least one parameter and / or the at least one further parameter. The control device can be corresponding to such an offsetting

be trained and suitable.

Preferably, the cooking device is designed so that it for the inventive

Method and preferably also suitable for the developments of the method.

Further advantages and features of the invention will become apparent from the embodiments, which are explained below with reference to the accompanying figures. In the figures show:

Figure 1 is a schematic representation of a cooking device according to the invention on a cooking appliance in a perspective view;

Figure 2 is a schematic cooking device in a sectional view;

3 shows a further cooking device in a schematic, sectional view;

Figure 4 shows another cooking device in a schematic, cut

View;

FIG. 5 a sketch of a profile of the output signals of the sensor units; and

Figure 6 is a sketch of another course of the output signals of the sensor units.

FIG. 1 shows a cooking device 1 according to the invention, which is here part of a

Cooking appliance 100 is executed. The cooking appliance 1 or the cooking appliance 100 can be designed both as a built-in appliance and as a self-sufficient cooking appliance 1 or stand-alone cooking appliance 100.

The cooking device 1 here comprises a hob 1 1 with four burners 21. Each of the cooking zones 21 here has at least one heated cooking area 31 for cooking food. In order to heat the cooking area 31, a heating device 2, not shown here, is provided in total for each hotplate 21. The heating devices 2 are designed as induction heating sources and each have an induction device 12 for this purpose.

However, it is also possible that a cooking area 31 is not assigned to any particular cooking area 21, but rather represents an arbitrary location on the hob 1 1. In this case, the cooking area 31 may have a plurality of induction devices 12 and in particular a plurality of induction coils and be formed as part of a so-called full-surface induction unit. For example, in such a cooking area 31 simply a pot can be placed anywhere on the hob 1 1, wherein during cooking only the corresponding induction coils are driven in the pot or are active. Other types of heaters 2 are also possible, such. As gas, infrared or

Widerstandsheizquellen.

The cooking device 1 can be operated here via the operating devices 105 of the cooking appliance 100. The cooking device 1 can also be used as a self-sufficient cooking device 1 with its own operating and control device to be formed. Also possible is an operation via a touch-sensitive surface or a touch screen or remotely via a computer, a smartphone or the like.

The cooking appliance 100 is here designed as a stove with a cooking chamber 103, which can be closed by a cooking chamber door 104. The cooking chamber 103 can be heated by various heat sources, such as a Umluftheizquelle. Other heat sources, such as a

Upper heat radiators and a lower heat radiator, and a Mikrowellenheizquelle or a vapor source and the like may be provided.

Furthermore, the cooking device 1, a measuring system 300 not shown here with a sensor device 3, which for detecting a first and a second

characteristic size for temperatures of the cooking area 31 is suitable. For example, the sensor device 3 can detect a variable, via which the temperature of a pot can be determined, which is turned off in the cooking area 31. Anyone can do this

Cooking area 31 and / or each hotplate 21 to be associated with a sensor device 3.

It is also possible that several cooking areas 31 and / or cooking zones 21 are provided, of which not all a sensor device 3 and / or at least two

have common sensor device 3.

The sensor device 3 is operatively connected to a control device 106 here. The

Control device 106 is designed to determine from the first and second characteristic variables the temperature of a cooking vessel 200 in the cooking area 31. Furthermore, the control device 106 is suitable and designed to determine a time derivative from the detected characteristic variables and to take this into account in the temperature determination as a parameter which describes a dynamic property of the measuring system 300. It can also do two or more separate and with each other

operatively connected control means 106 may be provided.

The cooking device 1 is preferably designed for an automatic cooking operation and has various automatic functions. For example, with the automatic function, a soup can be boiled briefly and then kept warm, without a user having to supervise the cooking process or set a heating level. For this he sets the pot with the soup on a hob 21 and selects the corresponding automatic function via the operating device 105, here z. As a boil with subsequent keeping warm at 60 ° C or 70 ° C or the like.

When using the automatic function, the temperature of the pot bottom is determined by means of the sensor device 3 during the cooking process. Depending on the measured values, the control device 106 sets the heating power of the heating device 2 accordingly. When reaching the desired temperature or boil the soup is the

Heating power down regulated. For example, it is also possible by the automatic function, a longer cooking process at one or more different desired

To carry out temperatures, z. B. to slowly let rice pudding draw.

In FIG. 2, a cooking device 1 is strong in a sectional side view

shown schematically. The cooking device 1 here has a carrier device 5 designed as a glass ceramic plate 15. The glass ceramic plate 15 can in particular as

Ceran field or the like may be formed or at least include such. Also possible are other types of support means 5. On the glass ceramic plate 15 is here a cookware or food containers 200, such as a pot or a pan, in which food or food can be cooked. Furthermore, a sensor device 3 is provided which detects heat radiation in a detection region 83 here. Of the

Detection area 83 is in installation position of the cooking device 1 above the

Sensor device 3 is provided and extends upward through the glass ceramic plate 15 to the food container 200 and beyond, if there is no food container 200 is placed there. Below the glass ceramic plate 15, an induction device 12 for heating the cooking area 31 is attached. The induction device 12 is here annular and has in the middle a recess in which the sensor device 3 is mounted. Such an arrangement of the sensor device 3 has the advantage that it is still in the detection range 83 of the sensor device even if the food container 200 is not centered on the cooking point 21.

FIG. 3 shows a schematized cooking device 1 in a sectional side view. The cooking device 1 has a glass ceramic plate 15, below which the

Induction device 12 and the sensor device 3 are mounted.

The sensor device 3 has a first sensor unit 13 and another sensor unit 23. Both sensor units 13, 23 are suitable for non-contact detection of thermal radiation and designed as a thermopile or thermopile. The sensor units 13, 23 are each equipped with a filter device 43, 53 and provided for detecting heat radiation emanating from the cooking area 31. The thermal radiation emanates, for example, from the bottom of a food container 200, penetrates the glass ceramic plate 15 and reaches the sensor units 13, 23. The sensor device 3 is advantageously mounted directly underneath the glass ceramic plate 15 in order to maximize the proportion of heat radiation emanating from the cooking region 31 without great losses to be able to capture. Thus, the sensor units 13, 23 are provided close to below the glass ceramic plate 15.

Furthermore, a magnetic shielding device 4 is provided, which consists of a ferrite body 14 here. The ferrite body 14 is here substantially as a hollow cylinder formed and annularly surrounds the sensor units 13, 23. The magnetic

Shielding device 4 shields the sensor device 3 against electromagnetic

Interactions and in particular against the electromagnetic field of the

Induction device 12 from. Without such shielding, the magnetic field generated by induction device 12 during operation could undesirably heat parts of sensor device 3 as well, resulting in unreliable temperature sensing and inferior measurement accuracy. The magnetic shielding device 4 thus considerably improves the accuracy and reproducibility of the temperature detection.

The magnetic shielding device 4 may also consist at least in part of at least one at least partially magnetic material and an at least partially electrically non-conductive material. The magnetic material and the electrically non-conductive material may be arranged alternately and in layers. Also possible are other materials or materials which have at least partially magnetic properties and also have electrically insulating properties or at least low electrical conductivity.

The sensor device 3 has at least one optical screen device 7, which is provided to shield radiation influences and in particular heat radiation, which act on the sensor units 13, 23 from outside the detection zone 83. For this purpose, the optical shield device 7 is designed here as a tube or a cylinder 17, wherein the cylinder 17 is hollow and the sensor units 13, 23 surrounds approximately annular. The cylinder 17 is made of stainless steel here. This has the advantage that the cylinder 17 has a reflective surface which reflects a large proportion of the much heat radiation or absorbs as little heat radiation as possible. The high reflectivity of the surface on the outside of the cylinder 17 is particularly advantageous for the shield against

Thermal radiation. The high reflectivity of the surface on the inside of the cylinder 17 is also advantageous in order to direct thermal radiation from (and in particular only out) the detection area 83 to the sensor units 13, 23. The optical screen device 7 can also be configured as a wall, which surrounds the sensor device 13, 23 at least partially and preferably annularly. The cross section may be round, polygonal, oval or rounded. Also possible is a configuration as a cone.

Furthermore, an insulation device 8 for thermal insulation is provided, which is arranged between the optical shield device 7 and the magnetic shielding device 4. The insulation device 8 consists here of an air layer 18, which is between the ferrite 14 and the cylinder 17. Preferably, there is no exchange with the ambient air to avoid convection. But it is also possible an exchange with the ambient air. By the insulation device 8 in particular a heat conduction from the ferrite 14 to the cylinder 17 is counteracted. In addition, the cylinder 17, as already mentioned above, equipped with a reflective surface to counteract heat transfer from the ferrite 14 to the cylinder 17 by heat radiation. Such an onion-bowl-like arrangement with an outer magnetic shielding device 4 and an inner optical shielding device 7 and an intermediate therebetween

Insulation device 8 provides a particularly good shielding of the sensor units 13, 23 from the effects of radiation from outside the detection range 83. This has a very advantageous effect on the reproducibility or reliability of the temperature detection. The insulation device 8 has, in particular, a thickness of between approximately 0.5 mm and 5 mm and preferably a thickness of 0.8 mm to 2 mm and particularly preferably a thickness of approximately 1 mm.

The isolation device 8 may also be at least one medium with a correspondingly low heat conduction, such. For example, a foam material and / or a polystyrene plastic or other suitable insulating material.

The sensor units 13, 23 are arranged here on a thermal compensation device 9 thermally conductive and in particular thermally conductive with the thermal

Balancing device 9 coupled. The thermal compensation device 9 has for this purpose two coupling devices, which are formed here as depressions, in which the

Sensor units 13, 23 are embedded accurately. This ensures that the sensor units 13, 23 are at a common and relatively constant temperature level. In addition, the thermal compensation device 9 ensures a homogeneous

Own temperature of the sensor unit 13, 23, when heated in the operation of the cooking device 1. An unequal own temperature can in particular as a thermopile

trained sensor units 13, 23 lead to artifacts in the detection. To avoid heating the thermal compensation device 9 by the cylinder 17, a spacing between cylinder 17 and thermal compensation device 9 is provided. The copper plate 19 may also be provided as the bottom 27 of the cylinder 17.

To enable a suitable thermal stabilization, the thermal

Compensation device 9 is formed here as a solid copper plate 19. However, it is also possible at least in part another material with a correspondingly high heat capacity and / or a high thermal conductivity.

The sensor device 3 here has a radiation source 63, which can be used to determine the reflection properties of the measuring system or the emissivity of a food container 200. The radiation source 63 is here designed as a lamp 1 1 1, which emits a signal in the wavelength range of the infrared light and the visible light. The radiation source 63 may also be formed as a diode or the like. The lamp 1 1 1 is used here in addition to the reflection determination for signaling the operating state of the cooking device 1.

In order to focus the radiation of the lamp 1 1 1 on the detection area 83, a portion of the thermal compensation device 9 and the copper plate 19 is formed as a reflector. For this purpose, the copper plate 19 has a concave-shaped depression, in which the lamp 1 1 1 is arranged. The copper plate 19 is also coated with a gold-containing coating to increase the reflectivity. The gold-containing layer has the advantage that it also protects the thermal compensation device 9 from corrosion.

The thermal compensation device 9 is executed on a plastic holder

Holding device 10 attached. The holding device 10 has a connecting device, not shown here, by means of which the holding device 10 can be latched to a support means 30. The support device 30 is formed here as a printed circuit board 50. On the support means 30 and the circuit board 50 also other components may be provided, such. As electronic components, control and computing devices and / or mounting or mounting elements.

Between the glass ceramic plate 15 and the induction device 12 is a

Sealing device 6 is provided, which is designed here as a micanite layer 16. The micanite layer 16 is used for thermal insulation, so that the induction device 12 is not heated by the heat of the cooking area 31. In addition, a micanite layer 16 for thermal insulation between the ferrite body 14 and the glass-ceramic plate 15 is provided here. This has the advantage that the heat transfer from the hot in the glass ceramic plate 15 to the ferrite 14 is severely limited. This goes from the

Ferrite body 14 hardly heat, which could be transferred to the isolation device 8 or the optical shield device. The micanite layer 16 thus counteracts an undesirable heat transfer to the sensor device 3, which increases the reliability of the measurements. In addition, the micanite layer 16 seals the sensor device 3 dust-tight against the remaining regions of the cooking device 1. The micanite layer 16 has

in particular a thickness between about 0.2 mm and 4 mm, preferably from 0.2 mm to 1, 5 mm and particularly preferably a thickness of 0.3 mm to 0.8 mm.

The cooking device 1 has on the underside a cover 41, which is designed here as an aluminum plate and the induction device 12 covers. The

Covering device 41 is connected to a housing 60 of the sensor device 3 via a

Screw 122 connected. Within the housing 60, the sensor device 3 is arranged elastically relative to the glass ceramic plate 15. For this purpose, a damping device 102 is provided, which here has a spring device 1 12. The spring device 1 12 is connected at a lower end to the inside of the housing 60 and at an upper end to the circuit board 50. In this case, the spring device 1 12 presses the printed circuit board 50 with the ferrite 14 and the attached thereto micanite 16 up against the glass ceramic plate 15. Such an elastic arrangement is particularly advantageous because the sensor device 3 may be arranged as close as possible to the glass ceramic plate 15 for metrological reasons should. This directly adjacent arrangement of

Sensor device 3 on the glass ceramic plate 15 could cause damage to the glass ceramic plate 15 in the event of impacts or impacts. Due to the elastic reception of the sensor device 3 relative to the carrier device 5, shocks or impacts are damped on the glass ceramic plate 15 and thus reliably prevent such damage.

An exemplary measurement in which the temperature of the bottom of a on the

Glass ceramic plate 15 standing pot to be determined with the sensor device 3 is briefly explained below:

During the measurement, the first sensor unit 13 detects outgoing from the bottom of the pot

Heat radiation as mixed radiation together with the heat radiation, which is emitted from the glass ceramic plate 15. In order to be able to determine therefrom a radiation power of the pot bottom, the proportion of the emanating from the glass ceramic plate 15

Radiation power out of the mixed radiation power. In order to determine this proportion, the other sensor unit 23 is provided to detect only the heat radiation of the glass-ceramic plate 15. For this purpose, the other sensor unit 23 has a

Filter device 53, which substantially only radiation with a wavelength greater than 5 μηη to the sensor unit 23 durchläset. The reason for this is that radiation with a wavelength greater than 5 μηη is not or hardly transmitted by the glass ceramic plate 15. The other sensor unit 23 thus essentially detects the heat radiation emitted by the glass ceramic plate 15. With the knowledge of the portion of the heat radiation, which of the

Glass ceramic plate 15 is emitted, can be determined in per se known, the proportion of heat radiation, which emanates from the bottom of the pot.

For a good measurement result, it is desirable for as much of the heat radiation emanating from the bottom of the pot to reach the first sensor unit 13 and to be detected by it. For radiation in the wavelength range of about 4 μηη has the

Glass ceramic plate 15 here has a transmission of about 50%. Thus, in this wavelength range, a large part of the heat radiation emanating from the bottom of the pot can pass through the glass-ceramic plate 15. Detection in this wavelength range is therefore particularly favorable. Accordingly, the first sensor unit 13 is equipped with a filter device 43 which is very permeable to radiation in this wavelength range, while the filter device 43 substantially reflects radiation from other wavelength ranges. The filter devices 43, 53 are each designed here as an interference filter and in particular as a bandpass filter or as a longpass filter.

The determination of a temperature from a specific radiant power is a known method. The decisive factor is that the emissivity of the body is known, from which the temperature is to be determined. In the present case, therefore, the emissivity of the pot bottom must be known or determined for a reliable temperature determination. The sensor device 3 here has the advantage that it is designed to determine the emissivity of a Gargutbehälters 200. This is particularly advantageous, since thus any cookware can be used and not just a specific food container whose emissivity must be known in advance.

In order to determine the emissivity of the pot bottom, the lamp 1 1 1 emits a signal which has a proportion of heat radiation in the wavelength range of the infrared light. The radiation power or the thermal radiation of the lamp 1 1 1 passes through the

Glass ceramic plate 15 on the bottom of the pot and is there partially reflected and partially absorbed. The reflected radiation passes through the glass ceramic plate 15 back to the sensor device 3, where it from the first sensor unit 13 as mixed radiation from

Pot bottom and is detected by the glass ceramic plate 15. At the same time as the reflected signal radiation, therefore, the own thermal radiation of the pot bottom and the glass ceramic plate also reaches the first sensor unit 13. Therefore, the lamp 11 is then switched off and only the thermal radiation of the pot bottom and the glass ceramic plate is detected. The proportion of the reflected signal radiation then results in principle from the previously detected total radiation minus the thermal radiation of the pot bottom and the glass ceramic plate.

With knowledge of the proportion of reflected from the bottom of the pot signal radiation of the

Absorbency of the pot bottom and thus its emissivity can be determined in a known manner, since the absorption capacity of a body in principle the

Emissivity of a body and the proportion of absorbed by the pot

Radiation equals 1 minus reflected radiation.

The emissivity is redetermined here at certain intervals. This has the advantage that a subsequent change in the emissivity does not lead to a falsified measurement result. A change in the emissivity may occur, for example, when the cookware bottom has different emissivities and is displaced on the cooking surface 21. Different emissivities are very common in cookware trays observed because z. B. already light soiling, corrosion or even different coatings or coatings can have a major impact on the emissivity. The lamp 1 1 1 is used here in addition to the determination of the emissivity or the determination of the reflection behavior of the measuring system for signaling the operating state of the cooking device 1. In this case, the signal of the lamp 1 1 1 also includes visible light, which is perceptible by the glass ceramic plate 15. For example, the lamp 1 1 1 indicates to a user that an automatic function is in operation. Such an automatic function can, for. B. be a cooking operation, in which the heater 2 is controlled automatically in dependence of the determined pot temperature. This is particularly advantageous because the lighting of the lamp 1 1 1 does not confuse the user. The user knows from experience that the lighting is an operation indicator and the normal appearance of the

Cooking device 1 belongs. He can therefore be sure that a flashing of the lamp 1 1 1 is not a malfunction and the cooking device 1 may not work properly.

The lamp 1 1 1 can also light up in a certain duration and at certain intervals. It is possible z. As well as that over different flashing frequencies

different operating states can be output. Different signals are also possible via different on / off sequences. Advantageously, a sensor device 3 with a radiation source 63, which is suitable for displaying at least one operating state, is provided for each cooking point 21 or each (possible) cooking region 31.

At least one arithmetic unit may be provided for the necessary calculations for determining the temperature and for the evaluation of the detected variables. The arithmetic unit can be at least partially provided on the circuit board 50. However, it is also possible, for example, for the control device 106 to be designed accordingly, or at least one separate arithmetic unit is provided.

FIG. 4 shows a development in which a safety sensor 73 is fastened below the glass-ceramic plate 15. The safety sensor 73 is here as a

temperature-sensitive resistor formed, such as a thermistor or an NTC sensor, and thermally conductively connected to the glass ceramic plate 15. Of the

Safety sensor 73 is provided here to be able to detect a temperature of the cooking area 31 and in particular of the glass ceramic plate 15. If the temperature exceeds a certain value, there is a risk of overheating and the heaters 2 are switched off. For this purpose, the safety sensor 73 with a not shown here

Safety device operatively connected, which can trigger a safety state depending on the detected temperature. Such a security condition has z. B. the shutdown of the heaters 2 and the cooking device 1 result.

In addition, the safety sensor 73 is here as another sensor unit 33 of

Sensor device 3 assigned. In this case, the detected by the security sensor 73 Values are also taken into account for the determination of the temperature by the sensor device 3. In particular, when determining the temperature of the glass-ceramic plate 15, the values of the safety sensor 73 are used. So z. B. the temperature, which was determined by means of the other sensor unit 23 on the detected thermal radiation, are compared with the temperature detected by the safety sensor 73. This adjustment can on the one hand serve to control the function of the sensor device 3, but on the other hand can also be used for a tuning or adjustment of the sensor device 3.

The task of the other sensor unit 23 can also be taken over by the safety sensor 73 in an embodiment not shown here. The safety sensor 73 serves to determine the temperature of the glass ceramic plate 15. For example, with knowledge of this temperature from the heat radiation, which detects the first sensor unit 13, the proportion of a pot bottom can be determined. Such a configuration has the advantage that the other sensor unit 23 and an associated filter device 53 can be saved.

As described above, the radiant power of the cooking vessel bottom can be determined from the mixed radiation detected by the first sensor unit 13. For this purpose, the heat radiation emanating from the glass ceramic plate 15 is detected by means of the second sensor unit 23 and calculated out of the mixed radiation. However, the calculation can be improved, as in some cooking situations, the useful signal of a usually much larger

Noise signal is covered.

For example, the components that are in the detection area 83 of the

Sensor device 3 are in operation and by the associated heating a significant amount of interference. This interference radiation can be described for example by a parameter which describes the current temperature of the components in the detection area 83. Since such a parameter describes the temperature at a particular time, it describes a property of the measurement system 300 that can be considered static. With appropriate consideration of this parameter in the calculation of the temperature from the individual signals or measured values, the reproducibility of the result can be significantly improved.

In order to detect the interference radiation in the detection region 83, the temperature at the first sensor unit 13 is detected here by means of a first sensor element 133. For the other sensor unit 23, a second sensor element 233 is provided. The sensor elements 133, 233 are integrated here in the sensor units 13, 23. The sensor elements 133, 233 are typically used in the sensor units 13, 23 designed as thermopile for determining the reference temperature. This embodiment is particularly advantageous because no additional sensors need to be installed, but simply existing sensor elements 133, 233 can be used. Thus, the accuracy of the sensor device 3 can be improved inexpensively.

In measurement mode, the first sensor unit 13 also detects a certain proportion

Radiation power of the glass ceramic plate 15, which does not detect the other sensor unit 23. Basically, this is not a problem, but this proportion behaves depending on the heat input into the glass ceramic plate 15. For example, a cooking situation in which the cooking vessel 200 is already very hot and thus has a high heat input into the

Glass ceramic plate 15 provides a different signal-to-noise ratio than a cooking situation with a relatively cold cooking vessel bottom.

Thus, the proportion of the heat input of the glass-ceramic plate 15 changes almost continuously as the temperature in the cooking area 31 changes accordingly. Therefore, it is very advantageous for an accurate temperature determination to reliably determine the current proportions of the respective radiant power and in particular the heat input of the glass-ceramic plate 15 into the measuring system 300 and to take appropriate account.

Therefore, the temperature of the Gargefäßbodens can be determined more accurately if the changes in the radiation components per unit time are taken into account in the evaluation of the noise components in the respective cooking situations. It is particularly advantageous that the time changes and thus the dynamic properties of the measuring system 300 are taken into account accordingly.

In order to take into account the dynamic properties of the measuring system 300, the output signals 130, 230 and in particular the amplified output signals of the first 13 and the other sensor unit 23 are registered here in each case and their temporal change is considered. For this purpose, for example, the slope of a regression line along different values of the output signals 130, 230 is considered. It is also possible to derive the output signals 130, 230 over time. In general, these parameters can be used, for example, to make a statement as to whether the measuring system 300 is more exposed to constant, falling or rising temperatures.

However, it is particularly advantageous that in each case one parameter is determined for the first 13 and the other sensor unit 23, whereby the changes in the respective proportions of the radiation power per unit time can be taken into account. Figures 5 and 6 show the intensities 303 of the output signal 130 of the first sensor unit 13 and the

Output 230 of the other sensor unit 23 over time 302.

In the figure 5, the output signal 130 of the first sensor unit 13 increases in the period 301 more than the output signal 230 of the other sensor unit 23. Such a situation is z. B. before, when the temperature of the pot rises sharply and the temperature of the Glass ceramic plate 15 but only slowly increases. Due to the lower increase in the glass ceramic temperature can be assumed that a lower noise component. This is reflected in particular in the lower value of the parameter, which is the slope or the derivative.

FIG. 6 shows a case in which the glass-ceramic temperature is higher than that of FIG

Pot temperature is quite high. The noise component is thus higher here than in the case of FIG. 5. A parameter which describes the slope of a regression line in the period 301 would therefore also be greater than the corresponding parameter in the case of FIG. 5. The changed proportion of the interference radiation thus finds itself in the changed parameter consideration.

When determining the temperature, the respective parameters together with the sensor sizes of the first 13 and the other sensor unit 23 and the values of the

Emissivity of the food container bottom charged accordingly. However, since the physical relationships are difficult to describe, an artificial neural network is preferably used to solve the problem of temperature calculation, which at the input of the respective sensor sizes, emission characteristics and parameters are supplied. Through targeted training, the artificial neural network can be adjusted robustly to the cooking and roasting situations. In this case, the artificial neural network can, so to speak, "learn" the calculation of the topsoil temperature from the above-mentioned values.

LIST OF REFERENCE NUMBERS

1 cooking facility

2 heating device

3 sensor device

4 magnetic shielding device

5 carrier device

6 sealing device

7 optical screen device

8 insulation device

9 thermal compensation device

10 holding device

1 1 hob

12 induction device

13 sensor unit

14 ferrite bodies

15 glass ceramic plate

16 Micanite shift

17 cylinders

18 air layer

19 copper plate

21 hotplate

23 sensor unit

27 floor

30 support device

31 cooking area

32 induction circuit unit

33 sensor unit

41 Covering device

43 Filter device

50 circuit board

53 Filter device

60 housings

63 radiation source

73 safety sensor

83 detection area

100 cooking appliance

102 damping device

103 cooking space 104 cooking chamber door

105 Operating device

106 control device

1 1 1 lamp

1 12 spring device

122 screw connection

130 output signal

133 sensor element

200 food containers

230 output signal

233 sensor element

300 measuring system

301 period

302 time

303 intensity

Claims

claims

1. Method for operating a cooking appliance (1) with at least one hob (1 1) and with at least one heating device (2) provided for heating at least one cooking area (31)

and at least one measuring system (300) having at least one sensor device (3) for detecting at least one first characteristic variable for temperatures of the cooking region (31),

characterized,

in that at least one parameter describing at least one dynamic property of the measuring system (300) is determined and for determining the temperature of the

Cooking area (31) is taken into account.

2. Method according to the preceding claim, characterized in that the parameter is determined taking into account a measured variable.

3. The method according to any one of the preceding claims, characterized in that the parameter is determined taking into account the first detected by the sensor device (3) characteristic size.

4. The method according to any one of the preceding claims, characterized in that the parameter at least one value for the temporal change of the

Sensor device (3) is detected first characteristic size, wherein

in particular, the parameter is at least one derivative of the first characteristic variable detected by the sensor device (3).

5. The method according to any one of the preceding claims, characterized in that the sensor device (3) at least partially from the cooking area (31) derived heat radiation as the first characteristic size for temperatures of

Cooking area (31) detected.

6. Method according to the preceding claim, characterized in that the heat radiation detected as the first characteristic quantity originates at least to a substantial extent from a cooking product container (200) positioned in the cooking region (31).

7. The method according to any one of the preceding claims, characterized in that the sensor device (3) as at least a second characteristic size

Thermal radiation detected, which at least a majority of one for positioning a food container (200) provided support means (5) emanates.

8. Method according to the preceding claim, characterized in that the temperature of the cooking zone (31) is determined from the first characteristic quantity taking into account the second characteristic variable.

9. Method according to the preceding claim, characterized in that the emission properties of the cooking area (31) for thermal radiation are at least partially taken into account.

10. The method according to any one of the preceding claims, characterized in that at least one further parameter determined and taken into account for determining the temperature of the cooking area (31), wherein the further parameter at least one static property of the measuring system (300) and in particular at least one temperature at least a portion of the sensor device (3) describes.

1 1. A method according to any one of the preceding claims, characterized in that the heating device (2) is controlled in dependence of the sensor device (3) detected first and / or second characteristic size.

12. The method according to any one of the preceding claims, characterized in that the heating device (2) is controlled in dependence of the determined under consideration of the parameter and / or the further parameter temperature of the cooking area (31).

13. Cooking device (1) with at least one hob (1 1) and with at least one for heating at least one cooking area (31) provided heating device (2) and at least one measuring system (300) with at least one sensor device (3) for detecting at least one first characteristic size for cooking zone temperatures (31),

wherein at least one control device (106) is provided for controlling the heating device (2) as a function of the first characteristic variable detected by the sensor device (3),

characterized,

in that the control device (106) is suitable and designed to determine at least one parameter describing at least one dynamic property of the measuring system (300) and to take into account the parameter for determining the temperature of the cooking zone (31).

14. Cooking device (1) according to the preceding claim, characterized in that the control device (106) is suitable and designed to determine the parameter from the time change of the sensor device (3) detected first characteristic variable.