EP2775786B1 - Cooking device - Google Patents

Description

The present invention relates to a cooking device comprising a hob with at least one cooking point and with a heating device provided for heating at least one cooking area.

In cooking appliances, automatic functions are increasingly desired. A prerequisite for an automatic operation of a cooking device is sometimes an accurate detection of various parameters, such as in particular z. As the temperature of the cookware or a food. In an automatic operation, for example, the heat source of the cooking device is controlled to z. B. to avoid overheating of the food. Therefore, the reproducibility or the accuracy of the detected parameters is usually crucial for the functionality of the automatic function and thus an important quality feature of a modern cooking appliance with automatic functions.

Devices have therefore become known in the prior art which determine contactless temperatures on a cooking pot. In the DE 10 2007 013 839 A1 For example, a cooktop sensor is described, which determines the temperature on the outside of a standing on a cooktop plate Gargutbehälters contact. A disadvantage of the hob sensor DE 10 2007 013 839 A However, it is that this is located above the hob, because it must not stand in the way other pots or objects on the hob during detection. The DE 10 2004 002 058 B3 and the WO 2008/148 529 A1 describe hobs and methods in which temperatures are determined contactless at the bottom of the food container. The WO 2008/148 529 A1 and the WO 2008/155922 A1 For this purpose, a heat sensor below the cooktop panel is provided, which detects thermal radiation and determines a temperature therefrom. Such a sensor device is also described in the documents EP 1 006 756 A1 and JP 2004 063451 A1 described. However, a disadvantage of non-contact methods is generally that scattered radiation can falsify the measurement result.

The publication EP 1 562 405 A1 discloses a cooktop with a sensor device, wherein the sensor device comprises at least one magnetic shielding device, a thermal insulation device and an optical shield device, and wherein the isolation device is at least partially disposed between the optical shield device and the magnetic shielding device.

Another possibility for determining the temperature during cooking and cooking processes is, for example, a temperature sensor integrated in the food container. However, the user must use special food containers and could no longer use his previous pots. Also disadvantageous is a temperature sensor, which is placed with the food in the pot, since the sensor must later be "fished out" of the food and should not be eaten by mistake.

It is therefore the object of the present invention to provide a cooking device which enables a reproducible detection of a physical quantity.

This object is achieved by a cooking device with the features of claim 1. Preferred features are the subject of the dependent claims. Further advantages and features will become apparent from the general description of the invention and the description of the embodiments.

The cooking device according to the invention comprises at least one hob with at least one cooking point and at least one heating device which is provided for heating at least one cooking area. At least one sensor device is provided for detecting at least one physical variable in a detection area. In this case, the sensor device has at least one sensor unit and at least one optical shielding device and at least one insulation device for thermal insulation. The optical screen device is at least partially disposed around the sensor unit to shield electromagnetic radiation from outside the detection area. The optical shield device is at least partially surrounded by the insulation device.

The cooking device according to the invention has many advantages. A considerable advantage is that at least one optical screen device is provided, which is arranged at least partially around the sensor unit. This can disturbing influences, such. B. heat radiation from Störstrahlern be prevented by the sensor unit. This has an advantageous effect on the reproducibility or reliability of a variable detected by the sensor device. Also advantageous is the at least one insulation device for thermal insulation, which at least partially surrounds the optical shielding device. As a result, in particular a heat transfer to the optical screen device is counteracted. By thus arranged combination of the optical shield device with the insulation device unwanted influences from outside the detection range of the sensor device can be particularly well shielded. If the sensor device is used, for example, for detecting a temperature, the detected values are particularly reliable.

The insulation device reliably keeps heat from the outside, so that the surface of the optical shield device has a lower temperature. As a result, the heat energy emitted by the optical screen device itself is significantly reduced. Since the optical screen device surrounds the sensor unit, radiation emitted by the optical screen device and impinging on the sensor unit acts directly as interference radiation, which falsifies the measurement result. The insulation device leads to a lower surface temperature and thus in a simple way directly to a better measurement quality of the non-contact determined physical size.

The optical shielding device can be configured as a wall which surrounds the sensor unit at least partially and preferably annularly. It is also preferred that the optical shielding device is at least partially made of a metallic material and in particular of a stainless steel. The shield device can also be made of a plastic or the like. In particular, the optical screen device is formed and / or coated from a material which is at least partially impermeable to light and / or infrared light and / or heat radiation.

Preferably, at least one inner surface area of the optical screen device is suitable and designed to guide light and / or heat radiation by reflection at least partially to the sensor unit. In particular, a surface area directed towards the sensor unit is designed in this way. For this purpose, the optical screen device can be coated at least in regions reflecting and in particular coated metallically. Also possible is an at least partially gilded and / or mirrored surface area.

Also preferably, at least one outer surface region of the optical shield device is suitable and designed to at least partially prevent thermal radiation by reflection and / or absorption from the sensor unit. In particular, a surface region of the optical shield device directed away from the sensor unit is designed in this way. For this purpose, at least one suitable coating can be provided on the outer surface area of the optical screen device, such. B. a reflective coating.

In particular, the optical screen device is at least partially tubular. Possible is a round or square or polygonal configuration.

The optical screen device is particularly preferably formed at least partially as a cylinder or comprises at least one such. The optical shield device may also be at least partially formed as a cone or cone. In particular, the optical screen device is at least partially hollow. Also possible is a configuration as a cone or as a so-called Winston cone.

The optical shield device may have at least one bottom. The floor may be formed at least partially reflective and / or impermeable to heat radiation and / or visible light. The floor can be provided in one piece and / or in several parts with the optical screen device. It is also possible that at least part of the sensor device is at least partially provided as a floor.

The isolation device consists in particular at least partially and in particular at least substantially completely of a material with low heat conduction. The isolation device is particularly suitable and designed to thermally isolate. In this case, the isolation device preferably comprises at least one medium with a correspondingly low heat conduction, such. As a foam material and / or a polystyrene plastic and / or other suitable insulating material.

The insulation device particularly preferably comprises or is formed from at least one gas layer and / or air layer. The air layer is bounded in particular by boundary walls or provided in an at least partially limited space. It is also possible that the isolation device has at least one area with a reduced pressure, wherein the pressure may be less than 1000mbar and preferably less than 100mbar. It is also possible a rough vacuum or a fine vacuum or a vacuum of a different quality.

In a preferred development, the hob has at least one carrier device, which is suitable and designed for positioning at least one Gargutbehälters and / or cookware. In particular, the sensor device is arranged in the installation position of the hob at least partially below the support means. In this case, the detection range of the sensor device in the installed position of the hob is at least partially provided above the sensor device.

The sensor device can have at least one magnetic shielding device. In this case, the insulation device can be arranged at least partially between the optical shield device and the magnetic shielding device. As a result, undesirable heat transfer from the magnetic shielding device to the optical shield device is considerably restricted or prevented.

It is possible and preferred that the heating device comprises at least one induction device. The magnetic shielding device is designed and suitable in particular for shielding electromagnetic interactions and in particular for shielding from the electromagnetic field of the induction device. Such a shielding of the magnetic field of the induction device is very advantageous, because thereby an induction of an electric field at least in parts of the sensor device counteracted. The unwanted induction of an electric field at least in parts of the sensor device could, for. B. lead to a warming of the sensor device, which would have a negative impact on the reproducibility of detection.

In particular, at least part of the magnetic shielding means consists of at least one at least partially magnetic material and one at least partially electrically non-conductive material. It is preferred that the magnetic shielding device is at least partially made of a ferrimagnetic material and / or of a ferrite material. Also possible is a ferrimagnetic ceramic material. 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. Particularly preferably, the magnetic shielding device is designed as at least one ferrite ring and / or a ferrite body or comprises at least one such.

In particular, the sensor device has at least one holding device. At least the magnetic shielding device, the optical shielding device and the insulation device can be received by the holding device at a defined distance from one another. This allows a simple and inexpensive installation of the sensor device. The holding device can also be provided at least partially as a bottom for the optical screen device.

Particularly preferably, at least one of the at least one sensor unit is suitable and designed for non-contact detection of at least one characteristic parameter for temperatures. The sensor unit is preferably designed and suitable for detecting or absorbing electromagnetic radiation, in particular in the wavelength range of the infrared radiation. Particularly preferably, the sensor unit is designed as a thermopile or a thermopile or comprises at least one such. The sensor unit can also have at least one thermocouple and in particular a plurality of thermocouples operatively connected to one another. Also possible are other thermal and / or pyroelectric sensors and / or bolometers and / or photoelectric detectors or photodiodes. The sensor unit may also be at least partially incorporated in an at least approximately vacuum.

The sensor device may also comprise at least one thermal compensation device. The thermal compensation device has in particular at least one coupling device which is suitable and designed to at least partially thermally conductively connect at least one of the at least one sensor unit to the thermal compensation device. Such an embodiment is particularly advantageous because temperature peaks can be compensated thereby and the sensor unit thus relatively constant over time Subject to conditions. Particularly in the case of sensor units for the contactless detection of at least one characteristic parameter for temperatures, such a thermal compensation is advantageous for the reliability of the detection. The thermal compensation device can also be provided at least partially as a bottom for the optical shield device.

The sensor device can have at least one radiation source. In this case, the radiation source is preferably surrounded by the optical screen device. In particular, the radiation source emits at least one signal, in particular in the wavelength range of the infrared light and / or visible light. The radiation source can be designed as a lamp and / or as a diode or the like.

Figur 1

eine schematische Darstellung einer erfindungsgemäßen Kocheinrichtung an einem Gargerät in perspektivischer Ansicht;

Figur 2

eine schematisierte Kocheinrichtung in einer geschnittenen Ansicht;

Figur 3

eine weitere Kocheinrichtung in einer schematischen, geschnittenen Ansicht;

Figur 4

eine weitere Ausgestaltung einer Kocheinrichtung in einer geschnittenen Ansicht;

Figur 5

eine andere Ausgestaltung einer Kocheinrichtung in einer geschnittenen Ansicht;

Figur 6

ein weiteres Ausführungsbeispiel einer Kocheinrichtung;

Figur 7

eine schematische Darstellung einer magnetischen Abschirmeinrichtung in perspektivischer Ansicht;

Figur 8

eine schematische, perspektivische Darstellung einer optischen Schirmeinrichtung;

Figur 9

eine schematische, perspektivische Darstellung einer thermischen Ausgleichseinrichtung;

Figur 10

eine schematische, perspektivische Darstellung einer Halteeinrichtung;

Figur 11

eine schematische, perspektivische Darstellung einer Sensoreinheit;

Figur 12a

eine schematisierte Sensoreinheit mit einer Filtereinrichtung in einer geschnittenen Darstellung;

Figur 12b

ein weiteres Ausführungsbeispiel einer Sensoreinheit mit einer Filtereinrichtung in einer geschnittenen Darstellung;

Figur 13

eine schematisierte Sensoreinrichtung in einer Draufsicht; und

Figur 14

eine Sensoreinrichtung in einer Explosionsdarstellung.

In the figures show:

FIG. 1

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

FIG. 2

a schematic cooking device in a sectional view;

FIG. 3

another cooking device in a schematic, sectional view;

FIG. 4

a further embodiment of a cooking device in a sectional view;

FIG. 5

another embodiment of a cooking device in a sectional view;

FIG. 6

another embodiment of a cooking device;

FIG. 7

a schematic representation of a magnetic shielding in perspective view;

FIG. 8

a schematic, perspective view of an optical shielding device;

FIG. 9

a schematic, perspective view of a thermal compensation device;

FIG. 10

a schematic, perspective view of a holding device;

FIG. 11

a schematic, perspective view of a sensor unit;

FIG. 12a

a schematic sensor unit with a filter device in a sectional view;

FIG. 12b

a further embodiment of a sensor unit with a filter device in a sectional view;

FIG. 13

a schematic sensor device in a plan view; and

FIG. 14

a sensor device in an exploded view.

The FIG. 1 shows a cooking device 1 according to the invention, which is designed here as part of a cooking appliance 100. 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 11 with four cooking zones 21. Each of the cooking zones 21 here has at least one heatable 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. But it is also possible that a cooking area 31 is not associated with any particular cooking area 21, but represents any location on the hob 11. 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 11, wherein during cooking only the corresponding induction coils are driven in the pot or are active. However, other types of heaters 2 are also possible, such as e.g. Gas, infrared or resistance heating sources.

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 designed as a self-sufficient cooking device 1 with its own operating and control device. 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 104 can be heated by various heating sources, such as a Umluftheizquelle. Other heating sources, such as a top heat radiator and a bottom heat radiator and a microwave heat source or a vapor source and the like may be provided.

Furthermore, the cooking device 1 on a sensor device 3, not shown here, which for detecting at least one at least one state of the cooking area 31st characterizing physical size 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. In this case, each cooking area 31 and / or each cooking place 21 can be assigned a sensor device 3. It is also possible that several cooking areas 31 and / or cooking zones 21 are provided, but not all of which have a sensor device 3. The sensor device 3 is operatively connected to a control device 106 here. The control device 106 is designed to control the heating devices 2 as a function of the parameters detected by the sensor device 3.

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.

By means of the sensor device 3, the temperature of the pot bottom is determined during the cooking process. Depending on the measured values, the control device 106 sets the heating power of the heating device 2 accordingly. In this case, the temperature of the bottom of the pot is monitored continuously, so that when the desired temperature or when boiling the soup, the heating power is regulated down. For example, it is also possible by the automatic function to perform a longer cooking process at one or more different desired temperatures, for. B. to slowly let rice pudding draw.

In the FIG. 2 a cooking device 1 is shown in a sectional side view very schematic. The cooking device 1 here has a carrier device 5 designed as a glass ceramic plate 15. The glass ceramic plate 15 may in particular be designed as a ceramic hob or the like or at least comprise 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. The detection area 83 is provided in the installed position of the cooking device 1 above the sensor device 3 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 a recess in the middle, 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. In other embodiments, not shown here, the sensor device 3 may also not be arranged centrally in the induction device. If an induction device has, for example, a dual-circuit induction coil, then at least one sensor device 3 can be arranged in a space provided between the two induction coils of the induction device.

The FIG. 3 shows a schematic 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 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 essentially designed here as a hollow cylinder and surrounds the sensor units 13, 23 in an annular manner. 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. 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 at least partially have magnetic properties and also have electrically insulating properties or at least a 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 shielding 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-dish-like arrangement with an outer magnetic shielding device 4 and an inner optical shield device 7 and an insulating device 8 located between them provides a particularly good shielding of the sensor units 13, 23 from radiation influences 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. B. include a foam material and / or a polystyrene plastic or other suitable insulating material.

The sensor units 13, 23 are arranged here in a thermally conductive manner on a thermal compensation device 9 and in particular are coupled in a thermally conductive manner to the thermal compensation device 9. The thermal compensation device 9 has for this purpose two coupling devices 29, 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 temperature of the sensor unit 13, 23, when it heats up during operation of the cooking device 1. An unequal own temperature can lead to artefacts during the detection, in particular in the case of sensor units 13, 23 designed as thermopiles. 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.

In order to enable a suitable thermal stabilization, the thermal compensation device 9 is designed 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 embodied here as a lamp 111, 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 111 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 111 onto the detection region 83, a region of the thermal compensation device 9 or the copper plate 19 is formed as a reflector 39. For this purpose, the copper plate 19 has a concave-shaped depression, in which the lamp 111 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 attached to a holding device 10 designed as a plastic holder. The holding device 10 has a connecting device 20, 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 printed circuit board 50 can also more Be provided components such. B electronic components, control and computing devices and / or mounting or mounting elements.

Between the glass ceramic plate 15 and the induction device 12, 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. As a result, hardly any heat emanates from the ferrite body 14, which could be transmitted to the insulation device 8 or the optical screen 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 microlayer 16 seals the sensor device 3 dust-tight against the remaining regions of the cooking device 1. In particular, the micanite layer 16 has 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 covers the Induktionseirichtung 12. The covering device 41 is connected to a housing 60 of the sensor device 3 via a screw connection 122. 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 has a spring device 112 here.

The spring device 112 is connected at a lower end to the inside of the housing 60 and at an upper end to the printed circuit board 50. The spring device 112 presses the printed circuit board 50 with the ferrite body 14 and the micanite layer 16 mounted thereon upwards against the glass ceramic plate 15. Such an elastic arrangement is particularly advantageous since the sensor device 3 should be arranged as close as possible to the glass ceramic plate 15 for metrological reasons , This directly adjacent arrangement of the 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 pot bottom of a standing on the glass ceramic plate 15 pot with the sensor device 3 is to be determined is briefly explained below:

During the measurement, the first sensor unit 13 detects heat radiation emanating from the bottom of the pot as mixed radiation together with the heat radiation which is emitted by the glass-ceramic plate 15. In order to be able to determine therefrom a radiation power of the pot bottom, the portion of the radiation output emanating from the glass ceramic plate 15 is calculated 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 transmits essentially only radiation having a wavelength greater than 5 μm to the sensor unit 23. The reason for this is that radiation with a wavelength greater than 5 microns 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 is emitted from the glass ceramic plate 15, 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 microns, 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 here each formed as an interference filter 433 and in particular designed as a bandpass filter or as a long-pass filter. In other embodiments, a detection of the radiation in the wavelength range between 3 .mu.m and 5 .mu.m and in particular in the range of 3.1 .mu.m to 4.2 .mu.m be provided, wherein the respective sensor unit and filter device is then respectively formed or adapted accordingly.

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.

To determine the emissivity of the pot bottom, the lamp 111 emits a signal, in particular a light signal, which has a proportion of heat radiation in the wavelength range of the infrared light. The radiant power or thermal radiation of the lamp 111 passes through the glass ceramic plate 15 on the bottom of the pot and is partially reflected there and partially absorbed. The radiation reflected from the bottom of the pot passes through the glass-ceramic plate 15 back to the sensor device 3, where it is detected by the first sensor unit 13. At the same time as the signal radiation reflected from the bottom of the pot and transmitted by the glass ceramic plate 15, the own thermal radiation of the pot bottom and the thermal radiation of the glass ceramic plate 15 reach the first sensor unit 13. Therefore, the lamp 111 is switched off and only the heat radiation of the pot bottom and the glass ceramic plate 15 is detected , The proportion of the reflected signal radiation, from which the emissivity of the pot bottom can be determined, then results in principle as the difference between the previously detected total radiation with the lamp 111 switched on minus the heat radiation of the pot bottom and the glass ceramic plate with the lamp 111 switched off.

According to one embodiment, at least one reference value with regard to reflected radiation and associated emissivity is deposited in a memory unit which cooperates with the sensor device and is not shown in the figures, wherein the memory unit can be arranged, for example, on the printed circuit board 50. The respective actual emissivity of the pot bottom can then be determined based on a comparison of the reflected signal radiation with the at least one reference value.

According to a further embodiment, the proportion of the signal radiation absorbed by the bottom of the pot is determined. This results according to methods known per se from the radiation power emitted by the lamp 111 less the signal radiation reflected from the bottom of the pot. The radiation power of the lamp 111 is either fixed and thus known or is determined for example by a measurement with the other sensor unit 23. The other sensor unit 23 detects a wavelength range of the signal radiation, which is almost completely reflected by the glass ceramic plate 15. Thus, the emitted radiation power can be determined in a very suitable approximation, whereby inter alia a wavelength dependence of the radiation line or the spectrum of the lamp 111 must be taken into account. With knowledge of the proportion of the absorbed signal from the bottom of the pot signal radiation, the degree of absorption of the pot bottom can be determined in a known manner. Since the absorption capacity of a body corresponds in principle to the emissivity of a body, the desired emissivity can be derived from the degree of absorption of the pot bottom. With the knowledge of the emissivity and the amount of thermal radiation, which emanates from the bottom of the pot, the temperature of the pot bottom can be determined very reliably.

The emissivity is preferably continuously redefined in the shortest possible 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 111 is also used here for signaling the operating state of the cooking device 1 in addition to the determination of the emissivity or the determination of the reflection behavior of the measuring system. In this case, the signal of the lamp 111 also includes visible light, which is perceptible by the glass-ceramic plate 15. For example, the lamp 111 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 up of the lamp 111 does not confuse the user. The user knows from experience that the lighting is an operation indicator and belongs to the normal appearance of the cooking device 1. He can therefore be sure that a flash of the lamp 111 is not a malfunction and the cooking device 1 may not work properly. The lamp 111 may also light up in a certain duration and at certain intervals. It is possible z. B. also that different operating states can be output via different flashing frequencies. 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.

The FIG. 4 shows a development in which below the glass ceramic plate 15, a security sensor 73 is attached. The safety sensor 73 is designed here as a temperature-sensitive resistor, such as a thermistor, in particular an NTC sensor, and thermally conductively connected to the glass ceramic plate 15. 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 turned off. For this purpose, the safety sensor 73 is operatively connected to a safety device, not shown here, 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 assigned here as a further sensor unit 33 of the sensor device 3. In this case, the values detected by the safety sensor 73 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.

In the FIG. 5 a sensor device 3 is likewise shown, in which a safety sensor 73 is assigned as a further sensor unit 33 to the sensor device 3. Unlike the one in the FIG. 4 described embodiment, but no other sensor unit 23 is provided here. The task of the other sensor unit 23 is taken over here by the safety sensor 73. The safety sensor 73 is used to determine the temperature of the glass ceramic plate 15. For example, with knowledge of this temperature from the thermal 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. The other sensor unit 23 may be referred to as a second sensor unit. The further sensor unit 33 may be referred to as a third sensor unit. In the embodiment according to Fig. 5 only the first sensor unit and the third sensor unit are provided.

Another embodiment of a cooking device 1 is in the FIG. 6 shown. Here, a common sealing device 6 for the induction device 12 and the ferrite body 14 of the sensor device 3 is provided. The sealing device 6 is designed as a micanite layer 16 which has a recess in the detection area 83 of the sensor device 3.

The FIG. 7 shows a schematic, magnetic shielding 4, which is formed as a hollow, cylindrical ferrite body 14. Such a configuration is particularly advantageous since the ferrite body 14 surrounds the areas and parts to be protected annularly. Preferably, the wall of the ferrite body 14 has a thickness of about 1 mm to 10 mm and in particular from 2 mm to 5 mm, and particularly preferably from 2.5 mm to 4 mm and in particular of 3 mm or more.

In the FIG. 8 is an optical shield device 7 shown schematically, which is designed here as a cylinder 17. The cylinder has here three locking devices 80, which are suitable for connection to a holding device 10.

A thermal compensation device 9 is in the FIG. 9 shown. The thermal compensation device 9 is designed as a copper plate 19. Preferably, the copper plate has a thickness of 0.5 mm to 4 mm or even 10 mm or more, and more preferably from 0.8 mm to 2 mm, and more preferably 1 mm or more. The copper plate 19 here has two coupling devices 29. The coupling device 29 is suitable and provided to receive a sensor unit 13, 23 thermally conductive. Furthermore, the copper plate 19 has a reflector device 39, which can reflect the radiation of a radiation source 63 and, in particular, can focus.

FIG. 10 shows a holding device 10, which is designed as a plastic holder. The holding device 10 preferably has a thickness between 0.3 mm and 3 mm or even 6 mm, and particularly preferably a thickness of 1 mm or more. The holding device 10 includes, for example, three connecting devices, of which only two connecting devices 20 are visible in the figure, by means of which the holding device 10 z. B. is connectable to a support device 30. Furthermore, the holding device 10 on three receiving devices 40, which are formed here as webs. The recording devices 40 are suitable for receiving the optical screen device 7 and arranging it at a defined distance from the magnetic shielding device 4. To carry out contacts receiving openings 70 are provided. The holding device 10 may also have further, not shown receptacles 40 which z. B. as a recess, survey, web and / or annular groove or the like may be formed. Such receiving devices 40 are provided in particular for the defined arrangement of a magnetic shielding device 4, an optical shield device 7, a thermal compensation device 9, an insulation device 8 and / or a support device 30.

In FIG. 11 a sensor unit 13 for non-contact detection of heat radiation is listed. The sensor unit 13 is designed as a thermopile or thermopile. The sensor unit 13 has contacts in order to connect them, for example, to a printed circuit board 50 or board. In an upper area of the sensor unit 13 is the area in which the heat radiation is detected. In this area, a filter device 43 is arranged here.

FIG. 12a shows a formed as a thermopile sensor unit 13 with a filter device 43 in a sectioned, schematic side view. The filter device 43 is arranged here on the region in which the thermal radiation impinges on the sensor unit 13 and is detected. The filter device 43 is here with an adhesive connection means 430 thermally conductively mounted on the sensor unit 13. The connecting means 430 here is an adhesive with a thermal conductivity of at least 1 W m ^-1 K ^-1 (W / (mK)) and preferably of 0.5 W m ^-1 K ^-1 (W / (mK)). Also possible and preferred is a thermal conductivity of more than 4 W m ^-1 K ^-1 (W / (mK)). As a result, heat can be dissipated from the filter device 43 to the sensor unit 43. The dissipation of the heat prevents the sensor unit 13 from detecting the self-heat of the filter device 43, which would lead to a falsified measurement result. For example, the heat from the filter device 43 via the sensor unit 13 can also be forwarded to the thermal compensation device 9 or the copper plate 19. Such indirect dissipation of the heat from the filter device 43 via the sensor unit 13 to the copper plate 19 is also particularly favorable since the copper plate 19 has a high heat capacity.

The adhesive may be, for example, a thermosetting, one-component, solvent-free silver-filled epoxy conductive adhesive. Due to the proportion of silver or silver-containing compounds a very favorable thermal conductivity is achieved. Also possible is a proportion of other metals or metal compounds with a corresponding thermal conductivity. Such an adhesive ensures a thermally conductive connection, which is durable and stable even at the temperatures to be expected in a cooking device 1.

The filter device 43 is designed as an interference filter 433 and here has four filter layers 432 with a different refractive index and with dielectric properties. In this case, filter layers 432 with higher and lower refractive indices are alternately stacked and connected. The filter layers 432 are, in particular, very thin, preferably a few nanometers to 25 nm. The carrier layer for the filter layers 432 here is a filter base 431 made of a silicon-containing material with a thickness of more than 0.2 mm. The filter device 43 is designed and suitable for transmitting a wavelength range in the infrared spectrum and for substantially reflecting radiation outside this range.

FIG. 12b shows a further embodiment of a sensor unit 13 with a filter device 43, wherein the filter device 43 is glued here only partially on the sensor device 13. The region in which the heat radiation strikes and is detected on the sensor unit 13 is surrounded here by a raised edge region. In this case, the connecting means 430 was applied only in an edge region. This has the advantage that the heat radiation to be detected does not have to pass through the connection means 430 before it strikes the sensor unit 13.

In the FIG. 13 a sensor device 3 is shown in a plan view. For clarity and distinctiveness, some parts or areas are shaded. It can be clearly seen that the sensor device 3 has a concentric structure according to the onion shell principle. Inside is a thermal Balancing device 9 or a copper plate 19, on which two sensor units 13, 23 and designed as a lamp 111 radiation source 63 are arranged. So that no unwanted heat radiation from the side of the sensor units 13, 23 is incident, the sensor units 13, 23 are surrounded by an optical screen device 7 and a cylinder 17. The cylinder 17 is spaced from the copper plate 19, so that as possible no heat transfer between the cylinder 17 and copper plate 19 can take place. The cylinder 17 is surrounded by a magnetic shielding device 4 and a ferrite body 14, respectively. The ferrite body 14 represents the outermost layer of the sensor device 3 and shields it against electromagnetic interactions.

Since the sensor device 3 is preferably provided as close as possible below a carrier device 5, a sealing device 6 or a micanite layer 16 lies on the ferrite body 14, which considerably reduces a heat transfer from the carrier device 5 to the ferrite body 14. Between the ferrite body 14 and the cylinder 17, an insulation device 8 is formed. The insulation device 8 is here an air layer 18. The air layer 18 counteracts a heat transfer from the ferrite body 14 to the cylinder 17. The sensor units 13, 23 in the interior of the sensor device 3 are thus very effective against interference, such. B. a magnetic field of an induction device 12, heat radiation from outside the detection range 83 and heating by heat conduction, protected. Such a configured, shell-like arrangement of the listed components significantly increases the reliability of the measurements performed with the sensor device 3.

The FIG. 14 shows a sensor device 3 in an exploded view. The items are here shown spatially separated from each other, whereby the arrangement of the items within the sensor device 3 is clearly visible. The concentric or onion-like structure is also clearly visible here. In addition to an improved measurement accuracy, such a structure also allows a particularly production-friendly and cost-effective installation of the sensor device 3.

When mounting the sensor device 3, the order of the individual parts or components can be designed differently. It is preferred that some components are already prefabricated. For example, a sensor unit 13, 23 may already be adhesively bonded to a filter device 43, 53 in a thermally conductive manner. Also, the circuit board 50 may already be partially equipped with electronic components prior to assembly. Preferably z. B. the radiation source 63 already contacted with the circuit board 50.

For example, the holding device 10 designed as a plastic holder is first mounted on the supporting device 30 designed as a printed circuit board 50. For this purpose, the holding device 10 at least one connecting device 20, not shown here, which with the PCB 50 connected and z. B. can be locked. A holding device 10 with three connecting devices 20 is in the FIG. 10 shown. Thereafter, the provided here as a copper plate 19 thermal compensation device 9 is inserted into the holding device 10. The sensor units 13, 23 designed as thermopiles or thermopiles are then passed through receiving openings 70 in the copper plate 19, the holding device 10 and the printed circuit board 50. A region of the sensor unit 13, 23, essentially the lower region of the sensor unit 13, 23 and in particular the lower housing part of the sensor unit 13, 23, is thermally conductively connected to the copper plate 19 and rests on the copper plate 19. Subsequently, the soldering of the corresponding contacts with the printed circuit board 50.

The mounting of the holding device 10, the copper plate 19 and the sensor units 13, 23 can also be performed in any other order. So z. B. first inserted the copper plate 19 in the holding device 10, then the sensor units 13, 23 inserted and subsequently the holding device 10 is locked to the circuit board 50. The contacting of the sensor units 13, 23 with the printed circuit board 50 can be done at any time during assembly.

The contacting of the radiation source 63 designed as a lamp 111 with the printed circuit board 50 can likewise take place at any desired time of assembly. It is preferred to contact the lamp 111 first with the printed circuit board 50 and then to start with the mounting option described above.

This is followed by the assembly of the optical screen device 7 designed as a cylinder 17. For this purpose, the cylinder 17 has three latching devices 80, which are latched to the three receiving devices 40 of the holding device 10. After that, the ferrite body 14 formed magnetic shield 4 is mounted on the holding device 10. For this purpose, the holding device 10 preferably has a further, not shown here receiving device 40, which may be formed as a recess, survey, web and / or annular groove or the like. As a result, it is possible in particular to accommodate the ferrite body 14 at a defined distance from the optical screen device 7, the thermal compensation device 9 and / or an insulation device 8. Subsequently, the sealing device 6 designed as micanite layer 16 is fastened to the magnetic shielding device 4. Other suitable mounting sequences for the cylinder 17, the ferrite body 14 and the sealing device 6 may be provided.

It can be provided on different parts of the sensor device 3 more locking connections or connectors or other conventional connection devices, which allow easy mounting and at the same time ensure reliable cohesion and a defined arrangement of the parts.

LIST OF REFERENCE NUMBERS

1

cooking facility

2

heater

3

sensor device

4

magnetic shielding device

5

support means

6

seal means

7

optical screen device

8th

isolation facility

9

thermal compensation device

10

holder

11

hob

12

inductor

13

sensor unit

14

ferrite

15

Glass ceramic plate

16

Mika Nitsch layer

17

cylinder

18

layer of air

19

copperplate

20

connecting device

21

cooking

23

sensor unit

26

seal means

27

ground

29

coupling device

30

support device

31

cooking area

33

sensor unit

39

reflector device

40

recording device

41

cover

43

filtering device

50

PCB

53

filtering device

60

casing

63

radiation source

70

receiving openings

73

security sensor

80

locking device

83

detection range

100

Cooking appliance

102

attenuator

103

oven

104

oven door

105

operating device

106

control device

111

lamp

112

spring means

122

screw

200

food to be cooked

430

connecting means

431

filter base

432

filter layer

433

interference filters

Claims (14)

1. Cooking device (1) comprising at least one hob (11) having at least one hot plate (21) and having at least one heating device (2) provided for heating at least one cooking region (31) and having at least one sensor device (3) for detecting at least one physical variable in a detection region (83),
   the sensor device (3) comprising at least one sensor unit (13) and at least one optical screen means (7) and at least one insulation device (8) for thermal insulation,
   the optical screen means (7) being arranged around the sensor unit (13) at least in part in order to shield against electromagnetic radiation from outside the detection region (83), and the optical screen means (7) being arranged so as to be surrounded by the insulation device (8) at least in part,
   the sensor device (3) comprising at least one magnetic shielding device (4) and the insulation device (8) being arranged between the optical screen means (7) and the magnetic shielding device (4) at least in part,
   characterised in that
   the sensor device (3) comprises at least one radiation source (63), which is surrounded by the optical screen means (7).
2. Cooking device (1) according to claim 1, characterised in that at least one inner surface region of the optical screen means (7) is suitable and designed for directing heat radiation to the sensor unit (13) at least in part by means of reflection.
3. Cooking device (1) according to either of the preceding claims, characterised in that at least one outer surface region of the optical screen means (7) is suitable and designed for keeping heat radiation away from the sensor unit (13) at least in part by means of reflection and/or absorption.
4. Cooking device (1) according to any of the preceding claims, characterised in that the optical screen means (7) has a tubular design at least in part.
5. Cooking device (1) according to any of the preceding claims, characterised in that the optical screen means (7) is designed as a cylinder (17) at least in part or at least comprises a cylinder.
6. Cooking device (1) according to any of the preceding claims, characterised in that the optical screen means (7) comprises at least one base (27), which is designed to reflect heat radiation and/or visible light at least in regions.
7. Cooking device (1) according to any of the preceding claims, characterised in that the insulation device (8) consists at least in part of a material having low thermal conductivity.
8. Cooking device (1) according to any of the preceding claims, characterised in that the insulation device (8) comprises an air layer (18).
9. Cooking device (1) according to any of the preceding claims, characterised in that the hob (11) comprises at least one support device (5), which is suitable and designed for positioning at least one container for food to be cooked, and in that the sensor device (3) is arranged below the support device (5) at least in part when the hob (11) is installed, the detection region of the sensor device (3) being provided above the sensor device (3) at least in part when the hob (11) is installed.
10. Cooking device (1) according to the preceding claim, characterised in that the heating device (2) comprises at least one induction device (12), and in that the magnetic shielding device (4) is suitable and designed for shielding against electromagnetic interactions and in particular for shielding against the electromagnetic field of the induction device (12).
11. Cooking device (1) according to any of the preceding claims, characterised in that the sensor device (3) comprises at least one holding device (10), it being possible for at least the magnetic shielding device (4), the optical screen means (7) and the insulation device (8) to be received at a defined distance from one another by means of the holding device (10).
12. Cooking device (1) according to claim 11, characterised in that the holding device (10) is provided as a base (27) for the optical screen means (7) at least in part.
13. Cooking device (1) according to any of the preceding claims, characterised in that the sensor unit (13) is suitable and designed for detecting at least one characteristic parameter for temperatures in a contact-free manner.
14. Cooking device (1) according to any of the preceding claims, characterised in that the sensor device (3) comprises at least one thermal compensation device (9), the thermal compensation device (9) having at least one coupling device (29) which is suitable and designed for thermally conductively connecting the sensor unit (13) to the thermal compensation device (9) at least in part.

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