EP3273165B1 - Cooking field device, and method for operating the same - Google Patents

Description

The present invention relates to a hob device comprising at least one mounting plate. The present invention also relates to a method for operating such a hob device.

Modern household appliances usually offer a number of program support and / or automatic programs to a user in order to make operating the household appliance particularly convenient.

Particularly in the case of cooking appliances, a user can be greatly assisted in the preparation of meals via partially or even fully automated cooking processes. For example, some hobs offer boiling point detection. Known boiling point detections often use structure-borne noise measurements to draw conclusions about a boiling process. Such methods usually work reliably.

However, it is disadvantageous that low power cannot be monitored with structure-borne noise measurements and that when cold food is added or refilled, the cooking process is not monitored until a boiling process is detected again via structure-borne noise measurement. A continuous adjustment of the output to the current heat demand cannot take place. In addition, monitoring several cooking vessels on one hob is difficult.

From the pamphlet DE 103 53 299 A1 it is known to continuously determine the weight of a food in a cooking vessel during preparation and to determine the chemical potential of the food. The change in the weight of the food can be used to determine the condition of the food as a function of the chemical potential of the food. The determination of the chemical potential is, however, time-consuming and imprecise.

It is therefore the object of the present invention to better support a user when preparing food on a hob.

This object is achieved by a hob device with the features of claim 1 and by a method for operating such a hob device with the features of claim 6. Preferred developments of the invention are the subject matter of Subclaims. Further advantages and features of the invention emerge from the exemplary embodiments.

The hob device according to the invention comprises at least one mounting plate and at least one, in particular at least two, weighing devices. The mounting plate is configured to accommodate at least one cooking vessel. The weighing devices are configured to detect a weight acting on the mounting plate in the installed position of the hob. Furthermore, at least one cooking vessel identification device is assigned to the mounting plate. The cooking vessel identification device is configured to detect the mounting surface of a cooking vessel arranged on the mounting plate.

The terms installation area and area of the bottom of the pot and pot size are used synonymously in the following.

The hob device according to the invention furthermore preferably comprises at least one heating device, by means of which cooking vessels standing on the mounting plate can be heated. In this case, the mounting plate is designed in particular as a Ceran disk on which one or more hotplates are made available. The heating device can preferably comprise at least one induction coil, at least one gas burner and / or at least one other type of thermal heating source.

Furthermore, at least one control device and / or at least one operating device is preferably provided, via which the power of at least one heating device for at least one hotplate can be set.

In addition, the hob device is designed in particular in such a way that a user is provided with at least one automatic program and / or at least one cooking assistance when preparing food on the hob device according to the invention. For this purpose, at least one control and / or regulating electronics is expediently included in the hob device or assigned to the hob device.

The hob device furthermore preferably comprises a housing device and / or a frame device. The weighing devices can be arranged between a frame device on the one hand and the mounting plate and / or the housing device on the other hand. In this case, the frame device is preferably fastened to the worktop and the remaining parts of the hob device are stored on the frame device by means of the weighing devices.

Other configurations of the hob device are also possible according to the invention. The frame device is preferably part of the housing device or is made available by the housing device and / or is designed as a separate component. For example, the weighing devices can be arranged between the housing device and / or frame device and / or the worktop on the one hand and the mounting plate on the other.

A particularly favorable embodiment provides that the weighing devices are held on the housing device and, in order to detect a weight, rest on the mounting plate on the one hand and on the frame device and / or the worktop on the other.

The weighing devices preferably include at least one sensor device, which is designed in particular as a weighing sensor. The force acting on the mounting plate can be determined via such a weighing sensor or via the weighing devices. For this purpose, the mounting plate preferably rests exclusively on the weighing devices, so that a load on the mounting plate acts particularly effectively on the weighing devices. In this way, a particularly detailed recording of the change in weight can be recognized, as a result of which a two-dimensional mapping of the cooking vessels placed on the mounting plate can take place particularly precisely. The mounting plate preferably rests directly or indirectly on the weighing devices.

The weighing devices are particularly preferably arranged on opposite sides of the hob or the frame device, so that a shift in weight or a change in weight on the hob or on the mounting plate can be determined particularly effectively and precisely.

According to the invention, at least one cooking vessel identification device is assigned to the mounting plate, this being understood in particular to mean that the cooking vessel identification device is part of the hob and / or is designed as a separate component. A pot position on the mounting plate can be recognized, for example, via such a cooking vessel identification device. However, it is also expediently possible to detect the pot, in which the type of pot and in particular the size of the pot is recognized. In particular, the diameter of the bottom of the pot can be recognized. Furthermore, depending on the design of the cooking vessel identification device, it can also be recognized what the filling level of the cooking vessel is and / or whether, for example, a lid is placed on the cooking vessel or not.

The cooking vessel identification device preferably comprises at least one induction coil or uses at least one induction coil of a heating device. A Pot position recognition or the recognition of the size of the pot or the pot bottom on the mounting plate can be recognized by a phase shift in the induction coils.

In other advantageous refinements, the cooking vessel identification device can also be made available alone or in addition by an optical detection device such as a camera or the like. A camera can be arranged, for example, above the hob device, in which case, in particular, the integration of a camera into an extractor hood arranged above the hob device can advantageously be used. A camera can preferably be used to identify both the position of cooking vessels on the installation surface and the size of the pot, a lid that has been placed on it and / or the level in a cooking vessel.

In expedient developments, the cooking vessel identification device can also be integrated into the operating device of the hob device. Then, for example, a user can use the operating device to set what kind of cooking vessel he is using. Information such as pot size, pot type, pot diameter or other parameters that are necessary for controlling a cooking process via the weight sensors can be fed to the hob device.

The hob device according to the invention offers many advantages. The weighing devices integrated in the hob device and the cooking vessel identification device can ensure particularly advantageous support for the user during a cooking process. In particular, a cooking assistant can be made available to a user, as is described in detail below for the method according to the invention for operating a hob device.

The frame device preferably comprises at least two shaped sections for receiving or fastening at least one weighing device in each case. In this case, shaped sections of this type provide in particular predetermined areas in which the weighing sensors are provided. Predefined locations can thus be specified, with six shaped sections being able to be provided, for example, in a rectangular frame device. Then, for example, a shaped section can be provided in each corner or near the corners and a shaped section can be provided in the middle of the two longitudinal sides. In this way, at least two or more weighing devices can be positioned to accommodate the mounting plate as required.

Three weighing devices are particularly preferably provided, which are arranged in particular in the shape of an equilateral triangle. If only two weighing devices are provided, one weighing device is in particular on one side of the frame device and weighing means arranged on the opposite side of the frame means.

Using at least three weighing devices, which are then preferably arranged in the form of an equilateral triangle, a two-dimensional map of the cooking vessels can be generated on the mounting plate, whereby changes in weight on the mounting plate can be precisely detected. Thus, even when using several cooking vessels on the hob device, a weight change can be assigned to a specific cooking vessel.

In the case of small hobs, for example a table-top unit with only one cooking zone, it is also possible to use only one weighing device. Load cells can be used here, which compensate for the moments that occur in the event of asymmetrical loading.

By evaluating the compensation for the asymmetrical load, it is possible that a two-dimensional map of the cooking vessels on the mounting plate can also be generated with two weighing devices or even with only one weighing device. The method according to the invention is particularly suitable for operating a hob device as has been described above. There is a weight detection by means of the weighing devices and a cooking vessel identification by means of the cooking vessel identification device. Conclusions are drawn about the state of a cooking vessel and / or about the state of at least one cooking process in at least one cooking vessel via weight detection and the cooking vessel identification.

A state of a cooking vessel is understood to mean in particular whether a lid is placed on the cooking vessel or not. Furthermore, a state of the cooking vessel is to be understood, inter alia, in particular as whether the cooking vessel is shifted, lifted, tilted, whether the cooking vessel is being stirred and / or what type of cooking vessel is being used.

According to the invention, a state of a cooking process in a cooking vessel is understood in particular to mean that it is determined whether, for example, a boiling point has been reached or whether a liquid is boiling in a cooking vessel.

A boiling impression is to be understood as the boiling behavior, in particular with regard to the density of the supplied heat output. With a low power density, few boiling bubbles appear on the bottom of the pot, the boiling impression is weak. A weak boiling impression is described, for example, as "low boiling" or "low boiling". With a high power density, many boiling bubbles form on the bottom of the pot, which may become too large Steam bubbles combine, the boiling impression is strong. A strong boiling impression is described, for example, as "strong boiling" or "bubbly boiling". To determine the boiling impression, it is necessary to determine the size of the pot or the cross-section of the cooking vessel. The amount of power supplied, the weight loss due to evaporation of liquid or the rate of weight loss, the time and the boiling impression can thus be related by calculations and derived from one another. For example, the time after which a certain boiling impression can be calculated can be calculated. According to the invention, it is therefore also possible to regulate to a specific boiling pressure over the long term.

According to the invention, the power of the heating device is controlled as a function of the power density. This makes it possible to obtain a certain boiling impression. The food in the fluid as a disturbance variable and heat sink is intrinsically taken into account in the method according to the invention and the device according to the invention.

According to one possible embodiment, the control device controls the supply of the heating power in order to regulate the boiling pressure as a function of the target boiling pressure.

Particularly preferably, the determined data for weight recognition and the cooking vessel identification are further processed by a control device or regulating electronics of the hob device and used to control the heating devices of a specific hob. A particularly precise and advantageous cooking assistance can thus be made available to a user.

The method according to the invention offers many advantages. In particular, the weight sensors and a position detection of a cooking vessel and / or the detection of a cooking vessel type and / or cooking vessel size can be used to control the heating devices for the corresponding hotplate particularly precisely.

In addition, certain actions can be automatically recognized by the hob device. For example, the weight sensors together with the cooking vessel identification can detect whether a lid is on or not. In addition, continued cooking can be regulated particularly precisely, with the hob device still being able to control a cooking process so precisely that emissions and energy are saved. In addition, the addition of food and the heat requirement of certain foods can be recognized, whereupon the output can be continuously and optimally adjusted.

With conventional methods, the differentiation of individual cooking vessels is only possible with great effort, if at all. In addition, structure-borne noise is often measured for boiling point detection, for example, but this means that lower powers cannot be monitored. These disadvantages are avoided by the hob device according to the invention and a user is provided with a particularly convenient cooking assistant.

At least one movement parameter is preferably determined. According to the invention, a movement parameter is understood to mean, inter alia, the displacement of a cooking vessel or the speed, the acceleration, deceleration, the path length, the direction and / or the rotation. Thus, a movement parameter can preferably be determined solely by shifting the weight of a cooking vessel or also together with the cooking vessel identification. Then, among other things, it can be recognized whether a pot is being moved or moved and where it is being moved. Furthermore, it can also be recognized whether a stirring movement is being carried out in a pot.

The weight is expediently continuously determined for all the cooking vessels arranged on the mounting plate, so that the cooking process in each cooking vessel can be controlled via the weight curve. A continuous determination is to be understood in particular to mean that so many values are measured that a sufficiently precise weight curve is determined.

At least one movement of a cooking vessel is particularly preferably converted into at least one control signal. In particular, a specific movement is determined or derived from at least one movement parameter. By converting a certain movement into a control signal, a certain action can be taken for a certain movement. For example, the output of at least one heating device can be changed or switched off. In addition, it is also possible for an extractor hood arranged above the hob device to be operated in a changed manner depending on the movement. For example, in the case of rapid stirring movements, it can be concluded that there is increased steam production in a cooking vessel. Then the performance of the extractor hood can be increased. By recognizing that a lid has been lifted, the extractor hood can be operated according to its output or even switched on first.

In expedient refinements, at least one heating device is controlled via the recognized state. In this way, the output of the heating device can preferably be continuously adapted to the currently required heat demand. This allows Emissions and energy can be saved effectively. Continued boiling or boiling down or reducing can also be advantageously achieved by means of a control of the heating device in relation to a recognized state.

ṁ

Wassermenge pro Zeit $\left[\frac{\mathit{kg}}{s}\right]$

P

zugeführte Wärmeleistung [kW]

ΔH

Verdampfungsenthalpie 2257

In preferred embodiments, a boiling point detection is carried out in at least one cooking vessel. This takes place in particular taking into account the weight recognition in connection with the cooking vessel identification. For this purpose, the weight of a cooking vessel is preferably measured essentially continuously during a cooking process. In particular, so many measurement points are recorded that a weight curve can be reliably determined. If a liquid such as water in the cooking vessel has already reached boiling temperature, the temperature of the liquid remains constant although energy is supplied. All energy supplied is converted into evaporation. It follows that the cooking vessel loses weight in proportion to the power supplied. A boiling point can be effectively recognized by this. With water, for example, the weight reduction is approx. 87.7 g / min with 3.3 kW heating power and approx. 26.6 g / min with 1 kW. The weight loss can be determined using the following formula: $$\dot{m}=\frac{P}{\mathrm{\Delta }H}$$

ṁ

Amount of water per time $\left[\frac{\mathit{kg}}{s}\right]$

P

supplied heat output [kW]

Δ H

Enthalpy of vaporization 2257

For example, for low boiling this is around 3.7 W / cm ² . For medium boiling in about 5.2 W / cm ² and for heavy boiling about 8.2 W / cm ² . The information about the installation area of the pot is preferably determined by means of the cooking vessel identification device. A weight loss of approx. 0.1 g / min per cm ^{2 of the} bottom of the pot, for medium boiling of approx. 0.14 g / min per cm ² and for high boiling 0.21 g can be used as a guideline for the weight loss for low boiling / min per cm ^{2 can be} assumed. For a small saucepan with a 14 cm diameter and low boiling, this means a weight change of 16 g / min. Measurements with scales have shown that it is possible to regulate cooking performance with a resolution of 1g that is far below the range where boiling noises can be heard. If cold food is now added to the boiling water, this can be seen in the absolute change in weight of the pot, but also in the change in weight over time. Rising steam bubbles condense on the cold food and the pot loses less weight with constant power. Analogously takes the boiling intensity also decreases because not as many vapor bubbles reach the surface. The control then increases the performance until the desired weight loss per time is achieved again. Liquids boiling over can also be detected by detecting excessive weight loss or shifting, since the weight then decreases faster than it corresponds to the amount of heat supplied or is shifted to an area outside the pot display area. For the latter, it is possible to detect the displacement of the weight by means of the identification device.

In the case of at least one cooking vessel, the status is preferably recognized as to whether a lid is on or not and / or whether a fill level change is being made. And a fill level change can in particular be understood to mean the refilling of liquid and / or the reduction of liquid.

It is particularly preferred via the control of the heating device and the weight recognition whether or not a lid is resting on a cooking vessel. For example, the heating device can be switched off briefly. It will then be checked how the weight reduction occurs in the course. If a lid is on the cooking vessel, rising steam will condense on the lid and run back into the cooking vessel. If the lid is not on, more steam will escape from the pot and the weight loss will be greater. After recognizing whether a lid is on or not, the power of the heating device can be set again to the power provided for the cooking process.

In useful developments, the weight loss of a cooking vessel is compared with the weight loss predetermined for the power used. If the weight of the cooking vessel decreases too quickly, this indicates that a liquid has boiled over.

Further advantages and features of the present invention emerge from the exemplary embodiments, which are explained below with reference to the accompanying figures.

Figur 1

eine rein schematische Darstellung einer erfindungsgemäßen Kochfeldeinrichtung in einer perspektivischen Ansicht;

Figur 2

eine rein schematische Darstellung einer erfindungsgemäßen Kochfeldeinrichtung in einer Ansicht von oben;

Figur 3

eine rein schematische Darstellung einer erfindungsgemäßen Kochfeldeinrichtung in einer Seitenansicht;

Figur 4

eine rein schematische Detailansicht von Bereich B in Figur 3; und

Figur 5

ein rein schematischer Gewichtsverlauf eines Gargefäßes während eines Garvorgangs.

In the figures show:

Figure 1

a purely schematic representation of a hob device according to the invention in a perspective view;

Figure 2

a purely schematic representation of a hob device according to the invention in a view from above;

Figure 3

a purely schematic representation of a hob device according to the invention in a side view;

Figure 4

a purely schematic detailed view of area B in FIG Figure 3 ; and

Figure 5

a purely schematic weight curve of a cooking vessel during a cooking process.

In Figure 1 a hob device 1 according to the invention is shown purely schematically, which in the exemplary embodiment shown is designed as a hob device 1 for installation in a worktop 100.

The hob device 1 comprises a housing device 2 which, in the exemplary embodiment shown, is inserted into a corresponding recess in the worktop 100. In the housing device 2, among other things, the power electronics and, in the exemplary embodiment shown, a plurality of inductors 7 of a heating device 8, via which cooking vessels protruding on the hob device 1 can be heated.

In order to place cooking vessels on the hob device 1, a mounting plate 4 is provided, which in the exemplary embodiment shown is provided by a ceran glass pane 9. This mounting plate 4 rests on weighing devices 5 which are fastened to a frame device 3. As a result, the force acting on the mounting plate 4 can be precisely determined by the weighing devices 5.

It is also indicated that several hotplates 10 are made available on the mounting plate 4, of which two hotplates 10 are shown purely schematically in the illustration shown.

The hob device 1 further comprises a cooking vessel identification device 50 which, in the exemplary embodiment shown, is integrated into the hob device 1. In the embodiment shown, the cooking vessel identification device 50 is made available by the inductors 7 of the hob device 1. Both the pot position and the pot size can be optimally determined via phase shifts in the inductors.

By evaluating the data of the weighing devices 5 or the weighing sensors and the cooking vessel identification device 50, a very detailed two-dimensional map of the mounting plate 4 or the weight distribution on the mounting plate 4 can be determined. For example, a change in weight can be determined very precisely for each individual cooking vessel via the weight sensors and the cooking vessel identification, even when several cooking vessels are standing up.

In Figure 2 is the in Figure 1 The hob device 1 shown is shown in a purely schematic view from above. Here, too, you can see the frame device 3 on which the Weighing devices 5 are attached. The mounting plate 4 rests on the weighing devices 5 in such a way that the forces acting on the mounting plate 4 can be evaluated via the weighing devices 5.

In this top view it can also be seen that a plurality of shaped sections 6 are provided in the frame device 3, via which contact with the weighing devices 5 can or should be established. In the illustrated embodiment, six shaped sections 6 are provided, three of which are provided on one longitudinal side 11 and three on the opposite longitudinal side 12.

Depending on the design of the hob device 1 and depending on the desired accuracy, a different number of weighing devices 5 can be integrated into the hob device 1. In particular, at least two weighing devices 5 are provided, which are then preferably arranged on different longitudinal sides 11, 12.

In the exemplary embodiment shown, three weighing devices 5 are provided, two of which are arranged on the longitudinal side 11 and one weighing device 5 is arranged on the other longitudinal side 12. In this case, the weighing devices 5 are provided or arranged or fastened in the mold sections 6 in such a way that a substantially equilateral triangle is formed by the weighing devices 5. This is indicated purely schematically by the dashed lines.

With such an arrangement of the weighing devices 5 in the manner of an equilateral triangle, the change in weight on the mounting plate 5 can be determined in a positionally precise manner. For example, the weighing sensors alone can determine at which point on the mounting plate 4 a change in weight takes place.

In conjunction with the cooking vessel identification device 50, this change in weight can be assigned to a specific cooking vessel, for example, with the combination of weighing sensors and cooking vessel identification making it possible to carry out a very specific evaluation of the weight change.

If, for example, a weight relief is detected at a certain point on the mounting plate 4, the cooking vessel identification device 50, which is provided here by the inductors 7 of the hob device 1, can recognize that the weight relief is taking place at an edge area of the cooking vessel. For example, it can be concluded that the weight is relieved by a tilting movement of the pot by lifting a handle of the pot.

In Figure 3 is shown purely schematically a side sectional view of a hob device according to the invention. The dashed boxes above and below the hob device 1 indicate that the vessel identification device 50 can be assigned to the hob device 1 depending on the configuration and is provided, for example, by inductors 7.

In other configurations, the cooking vessel identification device 50 can be assigned to the cooking device 1 or the mounting plate 4 as before, the cooking vessel identification device 50 then being integrated, for example, in the operating device of the hob device 1. Thus, according to the invention, it is also possible for the cooking appliance to be identified manually. Then, for example, a user can use the operating device to set what kind of cooking vessel he is using, so that, for example, the diameter of the bottom of the pot is known. A specific hotplate could then also be assigned to the cooking vessel in order to determine the position of the cooking vessel on the mounting plate if several cooking vessels are used. Such information can, for example, be stored in the operating device and / or the control device or added manually by a user.

The dashed box above the hob device 1 indicates that the cooking vessel identification device 50 can also be designed as a separate component, the cooking device identification device 50 then, for example, at least one image capturing device 51 such as B. comprises a camera 52. Such an external cooking vessel identification device 50, for example in the form of a camera 52, can advantageously be integrated, among other things, into an extractor hood above the hob device 1.

An effective detection of certain cooking vessels can also be achieved by means of such a cooking appliance identification device 50 in the form of an image acquisition device 51. Thus, among other things, the pot position and the pot type of various cooking vessels on the hob device 1 or on the mounting plate 4 can be precisely determined. In addition, such an optical cooking vessel identification device 50 can be used to quickly and easily identify whether a lid is resting on a cooking vessel or not and / or what the filling level is in a cooking vessel.

For example, by determining the level of a certain cooking vessel, the reduction of liquids can be optimally controlled. Then, for example, the thickening or reducing of sauces is possible by evaluating the data from the weighing devices 5 and of the cooking vessel identification device 50 and can be optimally controlled or regulated depending on the design of the hob device.

In Figure 4 is purely schematically an enlarged detail of the in Figure 3 with "B" labeled section. Here it is shown once again, purely schematically, how a weighing device 5 is arranged in a shaped section 6 of the frame device 3.

With a hob device 1 designed in this way, a user can be provided with particularly convenient cooking assistance. For example, automatic programs can use the data from the weighing devices 5 and the cooking vessel identification device 50 to control cooking processes.

In Figure 5 the weight curve over a certain section of a cooking process over time is shown purely schematically. The curve profile shown shows how a boiling point detection can be provided by means of the hob device 1 according to the invention using the weighing devices 5 and the cooking vessel identification device 50.

Thus, using the data determined by the weighing devices 5 and the cooking vessel identification device 50, a weight curve of a specific cooking vessel on the mounting plate 4 is monitored. At time t0, the weight of a specific cooking vessel is made up of the weight of the cooking vessel and the food in the cooking vessel, in this case water.

The cooking vessel is heated by means of a heating device and the weight does not initially change since the liquid in the cooking vessel must first heat up. At time t1, a lid was placed on the cooking vessel, which can be recognized here by an increase in a specific weight when a specific cooking vessel has been recognized by the cooking vessel identification device 50 and the weight of the lid for this cooking vessel is known. Otherwise, the resting position of a cover can also be determined experimentally as described later.

As the process progresses, the water begins to evaporate, which means that the weight of the cooking vessel begins to decrease. A boiling point can be recognized by the fact that the weight loss becomes constant over time.

At time t2, the lid was removed from the cooking vessel again, which is recognized by a specific weight reduction. At time t3, cold liquid was poured into the Cooking vessel refilled, the lid being placed on the cooking vessel again at time t4.

By adding cold liquid, the contents of the pot no longer boil, which means that the weight remains essentially constant. From the point in time t5, a decrease in weight per unit of time can be detected again, with a boiling point again being able to be recognized by the fact that the decrease in weight over time is constant.

In general, when a hob device of this type is operated, the reaching of a boiling point can be effectively detected. The weight of a cooking vessel is measured essentially continuously during a cooking process. In particular, so many measurement points are recorded that a weight curve can be reliably determined.

If the liquid in the cooking vessel has already reached boiling temperature, the temperature of the liquid remains constant, although energy is supplied. All energy supplied is converted into evaporation. It follows that the cooking vessel loses weight in proportion to the power supplied.

ṁ

Wassermenge pro Zeit $\left[\frac{\mathit{kg}}{s}\right]$

P

zugeführte Wärmeleistung [kW]

ΔH

Verdampfungsenthalpie 2257

In the case of water, for example, this is approx. 87.7 g / min with a heating output of 3.3 kW and approx. 26.6 g / min with 1 kW. The weight loss can be determined using the following formula: $$\dot{m}=\frac{P}{\mathrm{\Delta }H}$$

ṁ

Amount of water per time $\left[\frac{\mathit{kg}}{s}\right]$

P

supplied heat output [kW]

Δ H

Enthalpy of vaporization 2257

With conventional hobs, a user often assesses the strength of a boiling process on the basis of the formation of bubbles in the cooking vessel, e.g. weak, medium or strong cooking. In order to create a uniform impression of weak boiling for different pot diameters, the area of the pot bottom must be taken into account. A larger pot diameter is supplied with more power than a smaller one in order to produce a uniform impression of the slow boiling. The power density and thus the weight loss per unit of time and area remains constant.

For example, for low boiling this is around 3.7 W / cm ² . For medium boiling in about 5.2 W / cm ² and for heavy boiling about 8.2 W / cm ² . The information about the area of the pot is determined in the case of the hob device 1 according to the invention by means of the cooking vessel identification device 50. To determine the pot size In the embodiment shown, the inductors 7 of the heating device 8 are used. The pot diameter is determined from the electrical parameters of one or more induction generators via a phase shift. The cooking vessel identification device 50 is thus integrated into the hob device 1 in the exemplary embodiment shown. In other configurations, the cooking vessel identification device 50 can also be provided as a separate component. For example, the cooking vessel identification device 50 can include at least one image acquisition device 51, which is made available, for example, by a camera 52. A camera 52 can preferably be integrated into an extractor hood above the hob device.

This means that in order to set the boiling impression in a saucepan filled exclusively with water, only the diameter of the base of the saucepan is actually required and the desired power density can be set using the power of the hotplate. Unfortunately, this controlled operation does not work if there is a time-varying heat sink in the pot, for example from food to be heated. Some of the steam bubbles condense on the food and fewer steam bubbles reach the surface, which means that the boiling impression changes.

This disturbance variable can be taken into account when evaluating the weight loss per time according to the invention, since the time-variable heat sink is included in this measurement variable. Steam condensing on the food does not leave the pan and the weight loss over time is reduced. The output can then be continuously adapted to the heat demand of the food until the weight loss per time and area required for the desired boiling impression is restored.

A weight loss of approx. 0.1 g / min per cm ^{2 of the} bottom of the pot, for medium boiling of approx. 0.14 g / min per cm ² and for high boiling 0.21 g / min per cm, for example, can be used as guideline values for low boiling ^{2 are} accepted.

For a small saucepan with a 14 cm diameter and low boiling, this means a weight change of 16 g / min. Measurements with scales have shown that one can regulate cooking performance with 1g resolution that is far below the range where boiling noises can be heard.

If cold food is now added to the boiling water, this can be seen in the absolute change in weight of the pot, but also in the change in weight over time. Rising steam bubbles condense on the cold food and the pot loses it less weight with constant performance. Analogously, the boiling intensity also decreases because not as many vapor bubbles reach the surface.

The control then increases the performance until the desired weight loss per time is achieved again. If a lid is placed on the pot, this can also be determined by the absolute change in weight, since the lid has a certain weight. As with adding cold food, the change in weight will initially be smaller as steam condenses on the lid. The regulation also compensates for this.

The information about the presence of the lid can e.g. can be used to reduce the continued cooking power in order to avoid boiling over. If the pot with the lid on and an undefined amount of food was placed on the hob, an absolute change cannot be used to determine whether the lid is on the pot.

In this case it is possible to briefly interrupt the power supply after the boiling point has been reached. In the case of a pot with a lid, the absolute weight then remains constant because the lid prevents evaporation. With a pot without a lid, the water on the surface will evaporate and the weight will decrease further. At the same time, the water temperature falls with the weight. This makes it possible to measure whether the lid is resting on the pot or not. If a lid is placed on the pot, the rising steam will condense on it and the condensate will run back into the pot. The change in weight is therefore different for a cooking vessel with a lid than for a pot without a lid.

In general, all energy is used to heat the water during a heating process. Only when the water has reached a certain temperature does the water start to evaporate. Only part of the thermal energy is used to heat the water. The temperature curve of the water then becomes flatter.

As the temperature rises, more and more water in vapor form leaves the pot, the temperature curve becomes flatter and flatter until the boiling temperature is reached. Then the curve is horizontal.

For the weight of the pot this means that it is constant at the beginning and then decreases more and more until the weight decrease per unit of time at the boiling point becomes constant. In this way the boiling point can be identified.

The efficiency of the parboiling process can be increased by limiting the weight loss per unit of time to a maximum value. In this way, a higher percentage of energy is put into heating the water without the heating process being slowed down.

Through the positionally accurate determination of the weight loss, the cooking behavior in individual cooking vessels on the mounting plate 4 can thus be determined. It is thus possible, as previously described, to identify the boiling point for individual cooking vessels. In other application examples, continued boiling can also be optimally controlled or the reduction of liquids can be monitored, checked and controlled.

In general, it is possible according to the invention that the heat supply or the heating power for certain cooking vessels is optimally adapted to the current state of the cooking vessel contents by means of the hob device 1 designed according to the invention, whereby emissions and energy can be saved.

Furthermore, the cooking vessel identification device 50 and the weighing sensor system make it possible to detect certain movements in or on a cooking vessel and to convert these into at least one control signal. For example, it is possible that a stirring movement in a pot can be recognized, the weight sensor system being so sensitive that even the direction of the stirring movement can be recognized.

In addition, the displacement and / or rotation of a cooking vessel can be recognized, and certain actions can be initiated by such movements. For example, the cooking vessel identification device and the weighing sensor system can detect whether a cooking vessel is being removed from a specific hotplate. Then the previously used hotplate can be switched off, for example. Furthermore, strong stirring movements and / or the removal of a lid can also be recognized, so that, for example, external devices such as an extractor hood can also be operated with changed performance.

If you lose weight too quickly, liquids that boil over can also be detected, for example, since the weight then decreases faster than it corresponds to the amount of heat supplied.

List of reference symbols

1

Hob equipment

2

Housing equipment

3

Frame equipment

4th

Mounting plate

5

Weighing device

6th

Mold sections

7th

Inductor

8th

Heating device

9

Ceran glass pane

10

Hotplate

11

Long side

12

Long side

50

Cooking vessel identification device

51

Image capture device

52

camera

100

Countertop

Claims (13)

1. Hob device (1) comprising at least one support plate (4) which is designed to accommodate at least one cooking vessel, at least one heating device (8) which is designed to supply heating power to a cooking vessel positioned on the support plate (4) in order to heat a fluid in the cooking vessel, at least one control device by means of which the supply of the heating power can be controlled, and at least one, in particular at least two weighing devices (5) which are designed, when the hob device (1) is installed, to detect at least one weight acting on the support plate (4), characterised in that the support plate (4) is assigned at least one cooking vessel identification device (50) which is configured to detect the at least one footprint of a cooking vessel arranged on the support plate (4), the control device being configured to determine a curve of the change in the at least one weight over time, the control device being configured to control the heating device (8) depending on the quotient from the time curve of the at least one weight and the footprint.
2. Hob device (1) according to claim 1, wherein the hob device (1) comprises a control device which is configured to assign the at least one weight and the at least one footprint to a cooking vessel.
3. Hob device (1) according to either of the preceding claims, wherein the control device is configured to calculate the time after which a particular boiling impression occurs and/or, over a longer term, to regulate to a particular boiling impression, wherein a boiling impression is determined by the size and number of rising bubbles in the fluid.
4. Hob device (1) according to any of the preceding claims, characterised in that three weighing devices (5) are provided which are arranged in particular in the form of an equilateral triangle.
5. Hob device (1) according to any of the preceding claims, wherein the hob device (1) comprises an input device which is configured to detect a user input, in particular a target boiling impression.
6. Method for operating a hob device (1) according to any of the preceding claims, a boiling impression of its fluid being determined by the size and number of rising bubbles in the fluid, and the method comprising the following steps:

   a) the at least one weight of at least one cooking vessel which contains fluid is determined by the weighing devices (5) continuously or at particular time intervals or at particular times during preparation;

   b) heating power is supplied to the at least one fluid via the heating device (8);

   c) the information on the determined at least one weight is supplied to a control device for evaluation;
   characterised in that

   d) the at least one footprint or the pot size and the cross section of the vessel of at least one cooking vessel is determined by means of a cooking vessel identification device (50);

   e) the at least one footprint and the at least one weight are assigned to at least one heating device (8) by means of the control device;

   f) the boiling impression of the fluid is inferred by determining the pot size and the cross section of the cooking vessel, and the amount of power supplied, the weight loss due to evaporation of liquid or the weight loss rate, the time and the boiling impression are set in relation by means of calculations and derived from one another;

   g) and the supply of the heating power is controlled by the control device in order to influence the boiling impression.
7. Method according to the preceding claim 6, wherein at least one movement parameter is determined.
8. Method according to at least one of claims 6 or 7, wherein at least one movement of a cooking vessel is converted into at least one control signal.
9. Method according to at least one of claims 6 to 8, wherein a user input is detected by means of an input device and at least one of the following steps is carried out:

   aa) the current boiling impression is determined and/or stored in the control device as the target boiling impression;

   bb) a predefined target boiling impression or a stored target boiling impression is selected by the user input;

   cc) the control device controls the supply of the heating power in order to regulate the boiling impression depending on the target boiling impression.
10. Method according to at least one of claims 6 to 9, wherein the supply of the heating power is controlled on the basis of the evaluation of the curve of the boiling impression.
11. Method according to at least one of claims 6 to 10, wherein boiling point identification is carried out in at least one cooking vessel.
12. Method according to at least one of claims 6 to 11, wherein the state of the cooking vessel is identified for at least one cooking vessel and/or, by means of controlling the heating device and identifying the weight, it is identified whether a lid rests on a cooking vessel.
13. Method according to at least one of claims 6 to 12, wherein the change in weight of a cooking vessel is compared with the change in weight predetermined for the power used.

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