Method for operating a heating system and a kitchen appliance

Abstract

A method for operating an electric heating system of a kitchen appliance and a kitchen appliance for implementing the method are proposed, wherein a measured temperature of the heating system is determined by means of a temperature element for the purpose of calibrating the heating element and / or the measured temperature is compared with a heating temperature of the heating element determined by means of the heating element for the purpose of identifying a critical heating state. Also proposed is the use of the measured temperature determined by means of the temperature element of the heating system and the heating temperature determined by means of the heating element of the heating system for the purpose of identifying a critical heating state of the heating system.

Description

Technical Field

[0001] The invention relates to a method for operating a heating system of a kitchen appliance (machine, appliance, utensil) and a kitchen appliance for preparing food. Background Art

[0002] It is known that in electrically operated kitchen appliances, food / ingredients in a dish are heated by means of an electric heating system for preparing a dish / meal, wherein the (target) temperature of the heating system is specified as command variable / set point and the temperature is then measured as controlled variable in order to (feedback) control the heating system.

[0003] When the food is heated, unevenness of the food or an inclined position of the kitchen appliance, for example, can lead to locally different heat transfer processes from the heating system to the food and thus to local temperature variations. Strong local temperature increases - so-called hot spots - can not only burn / scorch the food and thus impair the cooking result, but can also damage the kitchen appliance.

[0004] Against this background, EP 3513698 A1 discloses a method for operating a heating system of a kitchen appliance, wherein the resistance of a heating element of the heating system is determined in order to detect local temperature changes of the heating element. Summary of the invention

[0005] The object of the present invention is to provide an improved method for operating a heating system of a kitchen appliance and an improved kitchen appliance for preparing food, which enable or support safer preparation of food and / or more precise and / or more reliable identification of critical heating states and / or local temperature changes.

[0006] The problem on which the invention is based is solved by a method, a use or a kitchen appliance according to embodiments of the application.

[0007] The proposed kitchen appliance is electrically operated, in particular a multifunctional device for preparing food / meals / dishes and / or for processing, in particular for heating, chopping and / or mixing food / ingredients.

[0008] For this purpose, the proposed kitchen appliance has an optional vessel for the food, an electric heating system for heating the food and / or a stirrer for stirring / mixing and / or chopping the food.

[0009] However, the kitchen appliance may also be any other machine for preparing, in particular for heating, food, such as a cooking range / stove, an oven, a microwave and / or a toaster.

[0010] For the purposes of the present invention, food is preferably a food material, a nutrient, a nutritional product, a beverage alcoholic beverage and / or a luxury food for consumption. Food can be, for example, a product of plant origin such as vegetables, fruit and / or (dry) cereal products, and / or a product of animal origin such as eggs, meat products and / or dairy products.

[0011] For purposes of the present invention, food may be solid, liquid, viscous, mushy, pasty, or the like.

[0012] For the purposes of the present invention, a food may be an initial, intermediate and / or final product for consumption and / or for a meal and / or dish. In particular, a food for the purposes of the present invention may form an ingredient for a dish and / or a meal and / or the food itself may be formed from a plurality of food materials and / or the food itself may be a dish and / or a meal.

[0013] In the case of the proposed kitchen appliance, the heating system is preferably at least partially integrated into the vessel, in particular into the bottom of the vessel. However, the heating system of the proposed kitchen appliance can also be arranged in a separate device such as a station to heat the vessel.

[0014] The proposed heating system of the kitchen appliance preferably comprises: a heating plate; an electric heating element / electrical conductor for generating thermal energy and / or for heating the heating plate; a measuring device for determining the resistance of the heating element; and / or a temperature element for determining a measured temperature, in particular for determining a measured temperature of the heating plate and / or of the vessel.

[0015] The heating element is preferably designed as a heating resistor, particularly preferably as a thermistor, in particular as an NTC thermistor or a PTC thermistor.

[0016] The electrical resistance of the heating element, hereinafter simply referred to as resistance, is temperature-dependent and / or changes with changes in the temperature of the heating element.

[0017] In the case of a PTC resistor / PTC thermistor, the resistance increases with increasing (average) temperature of the PTC resistor. Therefore, the PTC resistor has a positive temperature coefficient.

[0018] In the case of an NTC thermistor / NTC resistor, the resistance decreases as the (average) temperature of the NTC resistor increases. Therefore, the NTC resistor has a negative temperature coefficient.

[0019] Therefore, it is possible and provided in the proposed method to (metrologically) determine the resistance of the heating element, in particular to determine the (average) temperature of the heating element, hereinafter referred to as the heating temperature, by means of a measuring device, and / or to (feedback) control the heating system.

[0020] Due to manufacturing tolerances, the correlation between resistance and temperature is device-specific. For this reason, the correlation is preferably determined individually for each heating system and / or each kitchen appliance by means of calibration. Furthermore, the correlation may change over time, for example due to device wear, so that a recalibration / new calibration is necessary in order to (feedback) control the heating system based on the resistance and / or to reliably determine the heating temperature.

[0021] According to a first method variant of the proposed method, there is also provision for determining a (local) measured temperature of the heating system, in particular of the heating plate - in addition to the heating temperature - by means of a (separate) temperature element in order to carry out a calibration of the heating system, in particular of the heating element, for determining the heating temperature by means of a resistance.

[0022] According to a first method variant, a calibration of the heating system, in particular the heating element, is carried out with the aid of a temperature element, preferably in order subsequently - in particular exclusively and / or without the use of the temperature element - to determine the heating temperature based on the resistance of the heating element and / or in order to use the heating element as a resistance thermometer, in particular as a resistance thermometer for measuring over an area and / or in a local manner.

[0023] During calibration, preferably, the (first) resistance value / (first) resistance reference value of the heating element is assigned to the corresponding (first) heating temperature value / (first) heating temperature reference value of the heating element, preferably the resistance value is determined with the aid of a measuring device, and the heating temperature value is determined with the aid of the temperature element and / or the measured temperature value of the temperature element.

[0024] Particularly preferably, in the calibration a plurality of (different) resistance values ​​of the heating element are assigned to corresponding heating temperature values ​​of the heating element in order to determine the temperature coefficient of the heating element.

[0025] In particular, it is provided that a (second) resistance value / (second) resistance reference value of the heating element is assigned to a corresponding (second) heating temperature value / (second) heating temperature reference value of the heating element, preferably in order to determine the temperature coefficient by means of paired values.

[0026] In this way and / or with the aid of resistance values ​​and heating temperature values, a relationship and / or correlation between the resistance of the heating element and the heating temperature can be mathematically represented / established and preferably stored electronically, for example as a functional equation and / or table, in a data memory of the kitchen appliance.

[0027] Therefore, the use of temperature elements makes it possible to easily calibrate heating systems and / or kitchen appliances, in particular on site and / or by the user and / or independently of additional (external) measuring devices. In addition, calibration can be repeated multiple times, for example for each cooking process and / or after a certain period of time.

[0028] For the purposes of the present invention, the term "calibration" is preferably understood as a (separate) method step in which one or more resistance values ​​of the heating element, in particular one or more resistance values ​​determined by a measuring device, are assigned to one or more heating temperature values ​​determined by a temperature element, in particular in order to subsequently - exclusively and / or without the use of a temperature element - use the resistance of the heating element to determine the heating temperature.

[0029] According to a second method variant, which can also be implemented independently, a measured temperature determined with the aid of a temperature element, in particular during a heating operation and / or during use of the kitchen appliance, is compared with a heating temperature determined with the aid of a temperature element, in particular automatically, continuously and / or intermittently, in order to identify critical / unintended heating states and / or cooking states, in particular local temperature changes of the heating element.

[0030] In this way, critical heating states and / or local temperature increases can be detected particularly precisely and / or reliably compared to the prior art.

[0031] That is, a local temperature increase can lead to a change in the resistance of the heating element which is similar or identical to a slight uniform temperature increase of the heating element, so that the heating temperature determined exclusively by means of the resistance does not allow reliable conclusions to be drawn about the local temperature change.

[0032] A critical / unintended heating state and / or cooking state, hereinafter referred to as a critical heating state, is for the purposes of the present invention a state / condition of a heating system and / or a kitchen appliance, in which there is a local variation of the temperature of the heating element, in particular an increase and / or decrease of the temperature, compared to the other / overall (average) temperature or temperature distribution of the heating element. For example, a critical heating state and / or a local temperature variation exists if the temperature of the heating element at a point / location deviates by more than 5°C, 10°C or 30°C from the temperature of the closest surroundings at this point / location, in particular for a predetermined period of time, for example more than 5 seconds or 10 seconds.

[0033] The identification of a critical heating state is preferably carried out based on one or more predetermined criteria, in which the heating temperature and the measured temperature are compared with one another, in particular automatically, mathematically, meteringly and / or directly or indirectly. In particular, a critical heating state is present if - in particular preferably simultaneously and / or within a predetermined time period - one or more criteria are met / reached.

[0034] In the first criterion (gradient criterion), the gradient of the heating temperature is preferably compared with the gradient of the measuring temperature in order to identify a critical heating state. In particular, the difference between the gradients of the heating temperature and the measuring temperature is formed and compared with a predetermined limit value / threshold value / critical value, for example 2°C / s or 3°C / s.

[0035] If the gradient of the heating temperature is (significantly) above the gradient of the measuring temperature, for example by more than 2°C / s, and / or for a longer period of time, for example more than 5 seconds, and / or if a predetermined limit value is exceeded, the first criterion is met and / or there is a local temperature increase of the heating element which is only detected by the heating element and / or is not detected by the temperature element or is detected too late by the temperature element.

[0036] In a second criterion (difference criterion), the difference between the heating temperature and the measured temperature is formed and compared with a predetermined limit value / threshold value / critical value in order to identify a critical heating state.

[0037] If the difference between the heating temperature and the measured temperature is above a defined limit value, e.g. 20°C, 40°C or 60°C - in particular for a longer period of time, e.g. more than 5 seconds - the second criterion is met / reached and / or there is a local temperature increase of the heating element.

[0038] In the third criterion (absolute temperature criterion), the heating temperature and / or the measured temperature (each) are compared with a (corresponding) predetermined limit value / threshold value / critical value, such as 150° C., 200° C. or 240° C., in order to determine a critical heating state. The third criterion can in particular also be used to check the two criteria mentioned above.

[0039] In principle, the above criteria can be used independently of each other or in any combination to identify critical heating states.

[0040] According to a method variant, one or more criteria, in particular the sensitivity of the criteria and / or the limit values, are adjusted recipe-specifically, in particular depending on the food to be prepared and / or the type of food and / or the operating mode of the heating system and / or the kitchen appliance. For example, in a recipe requiring a high heat output, the difference between the gradient of the measured temperature and the heating temperature and / or the difference between the measured temperature and the heating temperature can be greater than the lower heat output required in the recipe, without one or more criteria being considered to be reached and / or without this being recognized as a critical heating state. Therefore, in such a recipe, the limit values ​​can be (automatically) adjusted.

[0041] According to a further, particularly preferred and independently realizable method variant, a first measured temperature of the heating system is determined by means of a first temperature element and a second measured temperature of the heating system is determined by means of a second (separate) temperature element in order to compare the heating temperature with the several measured temperatures and / or the first and second measured temperatures for the purpose of identifying critical heating states. In this way, local temperature changes can (also) be identified which occur in the vicinity of one of the temperature elements and which therefore cannot be identified by comparing the heating temperature with the measured temperature of the relevant temperature element.

[0042] In the proposed method, the operation of the kitchen appliance, in particular the heating system, can be (immediately) (automatically) adjusted when / as soon as a critical heating state is identified or after a critical heating state is identified, in particular to prevent local temperature changes identified in this way from having a negative impact on the operation of the kitchen appliance and / or the preparation of food.

[0043] Preferably, when / once or after a critical heating state is identified, a stirring process by means of a stirrer and / or a heating process by means of a heating system is (immediately) implemented, started, stopped and / or adjusted / regulated.

[0044] For example, when a critical heating state is detected, a stirrer of the kitchen appliance can be activated in order to even out the temperature and thus carry out a stirring process.

[0045] Additionally or alternatively, the heat output of the heating system can be reduced or heating by means of the heating system can be interrupted.

[0046] In this way, when / as soon as or after a critical heating state is detected, measures are taken (immediately), in particular automatically, to prevent damage to the food and / or the kitchen appliance.

[0047] Preferably, it is automatically checked / verified whether the measures taken and / or the adjustment of the operation of the kitchen appliance, in particular the heating system, have been successful, ie whether the temperature has been homogenized.

[0048] The proposed method therefore provides for a verification and / or plausibility check of the measures taken and for the adjustment of criteria and / or limit values ​​and / or measures as a function of the results.

[0049] For example, if the heating temperature and the measured temperature are not close to each other due to the stirring process, then - for example due to a wrong calibration and / or an overly sensitive standard - it may be a false alarm. In this case, a recalibration / new calibration can be (automatically) implemented.

[0050] Additionally or alternatively, the limit values ​​and / or the standards can be corrected accordingly to reduce the sensitivity.For the current production process, the comparison of the heating temperature and the measuring temperature can also be ignored and / or switched off.

[0051] If the heating temperature and the measured temperature approach too slowly, one or more measures can be adjusted and / or combined with one another. For example, the heat output can be reduced to a greater extent, the stirring process can be carried out longer and / or at a higher rotation speed, and / or additional measures can be taken.

[0052] If, on the other hand, the heating temperature and the measuring temperature approach each other too quickly, the heat output can be reduced to a lesser extent, the stirring process can be carried out for a shorter time and / or at a lower rotational speed and / or a measure can be omitted entirely.

[0053] According to a further aspect of the invention, which can also be implemented independently, the measured temperature determined by means of a temperature element of the heating system and the heating temperature determined by means of a heating element of the heating system, in particular a PTC thermistor, are used to identify a critical heating state of the heating system, wherein the heating element of the heating system exhibits a local temperature change. In this way, corresponding advantages are achieved.

[0054] The above-mentioned aspects, features, method steps and method variants of the invention as well as the aspects, features, method steps and method variants of the invention arising from the claims and the following description can in principle be implemented independently of one another, but can also be implemented in any combination and / or sequence. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Further aspects, advantages, features and properties / characteristics of the invention emerge from the claims and the following description of preferred embodiments with reference to the accompanying drawings. They are shown as:

[0056] Figure 1 A schematic side view of the proposed kitchen appliance with the proposed heating system for heating the preparation cavity;

[0057] Figure 2 according to Figure 1 A three-dimensional diagram of a heating system;

[0058] Figure 3 Schematic flow chart of the proposed method;

[0059] Figure 4 A schematic diagram with exemplary courses of heating temperatures and measured temperatures of a heating system when heating water;

[0060] Figure 5 A schematic diagram with exemplary trends of heating temperature and measured temperature when water is heated at a local dry spot on a heating plate using a heating system;

[0061] Figure 6 a schematic diagram with exemplary trends of heating temperature and measured temperature in the case where the heating plate is not fully wetted with water; and

[0062] Figure 7 Schematic diagram with exemplary trends of heating temperature and measured temperature when heating uneven food. DETAILED DESCRIPTION

[0063] In the drawings, some of which are not to scale and are merely schematic, the same reference numerals are used for identical, identical or similar parts and components, wherein corresponding or comparable properties and advantages may be obtained even if no repeated description is given.

[0064] Figure 1 Schematically illustrated is a proposed food processor / kitchen appliance 1 for preparation of food / meals / dishes and / or for processing of food / ingredients. The kitchen appliance 1 is preferably an electrically operated multifunctional kitchen appliance / food processor designed for chopping, stirring / mixing and / or heating / cooking food.

[0065] The kitchen appliance 1 preferably has a base 10 and / or a vessel / container 20 for receiving / holding food.

[0066] The base station 10 and the vessel 20 are preferably connected or can be electrically and / or mechanically connected, in particular to allow heating and / or mixing / stirring of food in the vessel 20. In addition, the following solution is also possible: in this solution, the base station 10 and the vessel 20 are additionally fluidly connected or can be fluidly connected, for example in order to conduct water vapor generated in the base station 10 into the vessel 20.

[0067] Figure 1The kitchen appliance 1 is shown in its normal state of use and / or in a connected position, wherein the vessel 20 is electrically and / or mechanically connected to the base station 10 .

[0068] The base 10 preferably has a receiving portion 10A to at least partially and / or at the bottom receive / accommodate the vessel 20. Particularly preferably, the vessel 20 can be at least partially inserted or suspended in the base 10 in order to connect the vessel 20 to the base 10 mechanically and / or electrically.

[0069] The vessel 20 has a wall 20W which delimits the preparation chamber ZR radially / laterally, a bottom 20B which delimits the preparation chamber ZR axially / from below.

[0070] The vessel 20 preferably has a cover 20D in order to delimit the preparation chamber ZR axially / from above and / or to close the vessel in a particularly securely pressed manner.

[0071] Optionally, the vessel 20 is provided with a handle 20G to simplify the handling of the vessel 20 .

[0072] In the embodiment shown, the vessel 20 is at least substantially round and / or cylindrical in shape. However, in principle, embodiments in which the vessel 20 is angular, in particular rectangular, are also possible.

[0073] The vessel 20 has a central axis A, wherein the central axis A passes centrally through the vessel 20 and / or the preparation chamber ZR, such as Figure 1 Indicated in.

[0074] Preferably, the center axis A is the longitudinal axis or axis of symmetry of the preferably elongated cylindrical and / or at least essentially rotationally symmetrical vessel 20 .

[0075] Optionally, the vessel 20 is equipped with a stirrer 20R, in particular for chopping and / or mixing food in the preparation cavity ZR. The stirrer 20R is preferably rotatably mounted and / or located at the bottom 20B of the vessel 20. The stirrer 20R preferably has a plurality of, in particular interchangeable, stirring blades / knives.

[0076] Preferably, the mixing blade has a cutting edge or is designed as a cutting blade for chopping food.

[0077] Preferably, the central axis A of the vessel 20 corresponds to the rotation axis of the stirrer 20R.

[0078] Preferably, the vessel 20 is mechanically connected or mechanically connectable to the base station 10 in order to drive the stirrer 20R by means of the base station 10 .

[0079] To drive the stirrer 20R, the kitchen appliance 1 , in particular the base station 10 , has an electric motor 10E which is connected or connectable to the stirrer 20R via a shaft 10W and / or which engages in a positive / positive manner from below in the base 20B in the connected position.

[0080] As already explained at the outset, the kitchen appliance 1 is designed to heat food and / or a medium in a vessel 20 and / or in a preparation chamber ZR.

[0081] For this purpose, the vessel 20 and / or the preparation chamber ZR are electrically heatable and / or the kitchen appliance 1 has an electrical heating system 20H.

[0082] The heating system 20H is designed for (direct) heating of the vessel 20, in particular for (direct) heating of the bottom 20B and / or the preparation chamber ZR. The heating system 20H is particularly preferably designed as a thick film heater.

[0083] In the embodiment shown, the heating system 20H is integrated into the vessel 20, in particular into the bottom 20B, and / or the heating system 20H or a part of the heating system 20H forms the bottom 20B or a part of the vessel 20. However, a configuration in which the base 10 has or forms the heating system 20H is also possible.

[0084] In order to be able to supply power to the base station 10 and / or the vessel 20, in particular to the heating system 20H and / or the electric motor 10E, the kitchen appliance 1, in particular the base station 10, is provided with a power supply unit 10N - preferably with appropriate charging electronics - and / or with a power cord 10C for connection to a mains power supply.

[0085] Preferably, the base station 10 has one or more electrical connections 10X and / or 10Y for the vessel 20 in order to electrically connect the vessel 20 - in the connection position - to the base station 10 and / or the power supply unit 10N and / or to supply the vessel with electrical energy / power.

[0086] The electrical connections 10X and / or 10Y are preferably integrated into the receiving portion 10A of the base station 10 , in particular so that an electrical connection is automatically established between the vessel 20 and the base station 10 by inserting the vessel 20 into the base station 10 .

[0087] The vessel 20 preferably has one or more electrical connections 20X and / or 20Y corresponding to the electrical connections 10X and / or 10Y, preferably wherein the electrical connections 20X and / or 20Y are located on the underside of the vessel 20 and / or the bottom 20B, such as Figure 1 Indicated in.

[0088] The electrical connections 10X / 10Y and 20X / 20Y are preferably formed by one or more electrical contacts or—particularly for wireless power transmission—by one or more coils.

[0089] The kitchen appliance 1, in particular the base station 10, preferably comprises a user interface 10U, a data processing device 10R, a control device 10S, a communication device 10K and / or a measuring device 10M, wherein the user interface 10U, the data processing device 10R, the control device 10S, the communication device 10K, the measuring device 10M, the power supply unit 10N, the heating system 20H, the motor 10E and / or the connection parts 10X, 10Y are preferably electrically connected to each other, such as Figure 1 Indicated by the dotted line in .

[0090] The user interface 10U is formed by at least one display device 10D, such as a screen, and at least one input device 10B, in particular a control element, such as a knob. Via the user interface 10U, a user of the kitchen appliance 1 can interact with the kitchen appliance 1, and / or the user can obtain and / or add one or more items of information to the kitchen appliance 1, such as information related to the operation of the kitchen appliance 1, the food to be prepared and / or the recipe to be used.

[0091] The data processing device 10R is preferably a device for evaluating, storing and / or processing one or more signals, data, measured values, reference values, information etc. In particular, the data processing device 10R has a computing unit such as a processor, and / or a (data) storage / memory, for example in the form of an SSD.

[0092] The control device 10S is preferably designed to control, in particular to activate or deactivate, the electric motor 10E and / or the stirrer 20R and / or the heating system 20H and / or to regulate the power of the electric motor 10E and / or the heating system 20H.

[0093] By means of the communication device 10K, the kitchen appliance 1 can be coupled (in terms of a data connection) to: one or more (external) devices, in particular mobile devices such as mobile phones; and / or devices, in particular central devices such as servers.

[0094] In particular, the communication device 10K enables a wired or wireless data connection between the kitchen appliance 1 and one or more devices or one or more equipment in order to: determine signals and / or information, in particular signals and / or information related to the operation of the kitchen appliance 1, the food to be prepared and / or the recipe to be used; and / or exchange such signals and / or information between the kitchen appliance 1 and the devices and / or equipment, wherein the data exchange and / or signal transmission can occur directly or indirectly.

[0095] For the purposes of the invention, a signal is preferably a means of transmitting information in the sense of information technology, a (modulated) wave, a bit sequence, a packet, etc. In particular, one or more pieces of information are assigned to the signal and / or are contained in the signal, which information can be transmitted by means of the signal.

[0096] The communication device 10K preferably comprises: a receiver for receiving signals; a transmitter for transmitting signals; and / or an interface, in particular a radio interface, a WPAN interface, a near field communication interface, an NFC interface, a WLAN interface or another particularly preferred wireless interface.

[0097] By means of the measuring device 10M, one or more measured variables of the kitchen appliance 1, in particular of the base 10 and / or the vessel 20, particularly preferably of the electric motor 10E and / or the heating system 20H, such as temperature, weight, voltage, current, resistance, rotational speed, pressure, air humidity and / or inclination, can be determined / measured (directly or indirectly). For this purpose, the measuring device 10M has one or more sensors and / or measuring units, such as temperature sensors, meters, voltage measuring units / voltmeters, current measuring units / ammeters, rotational speed measuring units / tachometers, pressure sensors, humidity sensors and / or inclination sensors.

[0098] Below, based on Figure 2 The structural design of the heating system 20H is described in more detail. Figures 3 to 7 The proposed method is described.

[0099] Figure 2 To prepare the cavity ZR from below and / or from away ( Figure 2 A perspective view of the heating system 20H is shown from one side (not shown).

[0100] The heating system 20H preferably comprises an electric heating device 20Q and / or a heating plate 20P, wherein the heating device 20Q is preferably designed to generate heat and / or to (uniformly) heat the heating plate 20P, and / or the heating plate 20P is designed to (uniformly) dissipate heat, in particular to dissipate heat to the preparation chamber ZR or the food located therein.

[0101] The heating system 20H is preferably designed to be flat and / or plate-shaped / disk-shaped, and in particular is designed so that the heating system 20H can be integrated into the bottom 20B of the vessel 20 .

[0102] The heating system 20H, in particular the heating device 20Q and / or the heating plate 20P, is preferably annular and / or disc-shaped, and / or in particular has a central opening 20A to at least partially accommodate / receive the motor 10E, the shaft 10W and / or the stirrer 20R. In other words, the heating system 20H, in particular the heating device 20Q and / or the heating plate 20P, extends annularly around the motor 10E, the shaft 10W and / or the stirrer 20R.

[0103] The heating plate 20P is preferably designed as a heat exchanger and / or is designed to dissipate the heat generated by the heating device 20Q, in particular to the preparation chamber ZR, and / or to transfer heat to the vessel 20 and / or the food in the preparation chamber ZR. For this purpose, the heating plate 20P is preferably made entirely or partially of metal, in particular of copper, aluminum and / or stainless steel.

[0104] Preferably, the heating plate 20P delimits the preparation chamber ZR downwards and / or the heating plate 20P forms the bottom 20B of the vessel 20 or a part thereof. In particular, the heating plate 20P is in (direct) contact with the food during its preparation.

[0105] The heating plate 20P is preferably arranged between the heating device 20Q and the preparation chamber ZR and / or separates the heating device 20Q from the preparation chamber ZR.

[0106] The heating plate 20P preferably has a heating surface 20F on the top side and / or the side facing the preparation chamber ZR, and has a contact surface 20K on the bottom side and / or the side facing away from the preparation chamber ZR, preferably wherein the heating plate 20P with the contact surface 20K rests on the heating device 20Q with its entire area.

[0107] The heating plate 20P may be designed to have one or more layers.

[0108] Preferably, at least the layer / side of the heating plate 20P facing the preparation chamber ZR is food-safe and / or made of stainless steel.

[0109] The heating system 20H, in particular the heating device 20Q, preferably comprises at least one heating element 20E and / or a carrier layer 20S, preferably wherein the heating element 20E is arranged on or in the carrier layer 20S and / or is electrically insulated from the heating plate 20P by the carrier layer 20S. In particular, the carrier layer 20S is made of an electrically insulating material, such as fiber-reinforced plastic, so as to electrically insulate the heating element 20E.

[0110] The heating element 20E is preferably designed as an electrical (elongated) conductor, particularly preferably as a thermistor, particularly as a PTC resistor / PTC thermistor. However, solutions are also possible in which the heating element 20E is designed as an NTC thermistor / NTC resistor.

[0111] Preferably, when current flows through the heating element 20E, the heating element converts electrical energy into thermal energy and / or the heating element 20E is heated, in particular, heated to a heating temperature HT.

[0112] In order to supply electric energy to the heating element 20E, the heating system 20H, in particular the heating device 20Q, has an electrical connection 20X, preferably wherein the electrical connection 20X is formed by two electrical contacts. However, embodiments are also possible in which the heating system 20H, in particular the heating device 20Q, is supplied with electric energy by induction.

[0113] Preferably, the heating system 20H and / or the heating device 20Q, in particular the heating element 20E, is electrically connected or can be electrically connected to the measuring device 10M, the control device 10S, the data processing device 10R, the user interface 10U, the communication device 10K and / or the power supply unit 10N via the electrical connection part 20X of the heating system 20H and the electrical connection part 10X of the base 10.

[0114] In the embodiment shown, the heating element 20E is spirally formed and / or wound around the opening 20A. However, other arrangements and / or windings are also possible here, for example other arrangements and / or windings in which the heating element 20E is in a meandering shape are also possible.

[0115] Preferably, the heating element 20E extends in a plane, in particular wherein the plane formed by the heating element 20E is at least substantially parallel to the heating plate 20P, in particular parallel to the heating surface 20F and / or the contact surface 20K, and / or orthogonal to the central axis A of the vessel 20.

[0116] Preferably, the heating element 20E has or forms a first and / or regional - in the embodiment shown as a spiral - measurement position / region M1 for (directly or indirectly) determining / measuring the heating temperature HT. In particular, the (surface) area of ​​the heating element 20E corresponds to the area of ​​the first measurement position / regional measurement position M1.

[0117] Particularly preferably, the area of ​​the heating element 20E and / or the first measuring location / region measuring location M1 is at least 10%, 20% or 30% of the area of ​​the heating plate 20P, in particular the heating surface 20F and / or the contact surface 20K.

[0118] As explained at the outset, the resistance R of the heating element 20E, hereinafter simply referred to as resistance R, varies with the heating temperature HT.

[0119] The heating temperature HT is preferably the temperature of the heating element 20E, in particular the mean temperature / average temperature and / or averaged temperature and / or regional temperature over the entire length / area of ​​the heating element 20E, and / or is preferably the temperature present at the first measuring position / regional measuring position M1.

[0120] Preferably, the resistance R of the heating element 20E increases with the increase of the heating temperature HT, and particularly preferably, approximately according to the following linear equation:

[0121] R=R1[1+TCR(HT-HT1)],

[0122] Wherein, HT1 in [°C] is used as the first heating temperature value and / or the reference heating temperature value at time t1, wherein R1 in [Ω] is used as the first resistance value and / or the reference resistance value at the first heating temperature value HT1 and / or at time t1, and wherein TCR in [1 / °C] is used as the (positive) temperature coefficient and / or the resistance increase value of the heating element 20E. However, other, in particular nonlinear, equations can also be used here to mathematically represent the relationship between the resistance R and the heating temperature HT.

[0123] Due to this correlation, the heating element 20E can be used as a resistance thermometer, in particular for measuring in a region, and / or the heating temperature HT can be determined with the aid of the resistance R, preferably wherein the resistance R is determined with the aid of a measuring device 10M and / or by current and voltage measurement.

[0124] Preferably, the first heating temperature value HT1, the first resistance value R1 and / or the temperature coefficient TCR are determined by calibrating the kitchen appliance 1, in particular by calibrating the heating system 20H, and / or are electronically stored in the data processing device 10R of the base station 10 and / or in a central device such as a server.

[0125] The kitchen appliance 1 , in particular the heating system 20H, preferably has a temperature element 20T for determining a measured temperature MT.

[0126] The temperature element 20T is preferably designed as a temperature sensor and / or a thermometer and particularly preferably as a (locally measuring) resistance thermometer, in particular an NTC sensor.

[0127] The temperature element 20T is preferably placed and / or fixed (directly) to the heating plate 20P. In the embodiment shown, the temperature element 20T is located in the opening 20A. However, other solutions are also possible, for example, other solutions in which the temperature element 20T is arranged and / or fixed on or to the heating surface 20F, the wall 20W or the stirrer 20R are also possible.

[0128] The temperature element 20T is preferably electrically connected to a second electrical connection 20Y, preferably wherein the second electrical connection 20Y is located on a side of the heating system 20H and / or the heating device 20Q facing away from the preparation chamber ZR and / or on the lower side of the heating system 20H and / or the heating device 20Q.

[0129] Preferably, the temperature element 2OT is electrically connected or connectable to the measuring device 10M, the control device 10S, the data processing device 10R, the user interface 10U, the communication device 10K and / or the power supply unit 10N via the electrical connection part 20Y of the vessel 20 and the electrical connection part 10Y of the base 10.

[0130] Preferably, the temperature element 20T is designed exclusively for measuring the measurement temperature MT. However, the temperature element 20T can also be designed and / or used as a (further) heating element. In particular, the temperature element 20T can be used additionally or alternatively - in particular as required - to generate heat.

[0131] The temperature element 20T preferably has or forms a second and / or local measurement location / area M2 for (directly or indirectly) determining / measuring the measurement temperature MT.

[0132] The measured temperature MT is preferably the temperature determined by the temperature element 20T and / or the temperature at the measuring position M2. In particular, the measured temperature MT is the (average) temperature of the heating plate 20P at the measuring position M2.

[0133] The heating element 20E and / or the first measurement location / region measurement location M1 is preferably larger than the temperature element 20T and / or the second measurement location M2 and / or has a larger (surface) area than the temperature element and / or the second measurement location, preferably at least five or ten times larger.

[0134] Preferably, the temperature element 20T and / or the second measuring point M2 are spaced apart from the heating element 20E and / or the first measuring point M1 , particularly preferably radially and / or axially and / or by at least 0.5 cm or 1 cm.

[0135] Particularly preferably, the temperature element 20T and / or the second measuring point M2 are closer to the preparation chamber ZR than the heating element 20E and / or the first measuring point M1 .

[0136] In particular, due to the distance of the temperature element 20T and / or the second measuring position M2 from the heating element 20E and / or the first measuring position M1 , the measured temperature MT is lower than the heating temperature HT, in particular at least 5° C. or 10° C. lower.

[0137] In the following, use Figures 3 to 7 The proposed method for operating and / or (feedback) controlling a kitchen appliance 1 and / or an electric heating system 20H is described.

[0138] The proposed method is preferably carried out by and / or in the kitchen appliance 1 , in particular by means of the heating system 20H, the control device 10S, the measuring device 10M, the data processing device 10R and / or the electric motor 10E.

[0139] As explained above, critical heating situations / states and / or local temperature changes of the heating system 20H, in particular of the heating plate 20P and / or the heating element 20E, are to be identified / detected using the proposed method.

[0140] For this purpose, the measurement temperature MT and the heating temperature HT and / or the resistance R are determined and compared with one another, in particular by signal comparison and / or metering means.

[0141] The method is preferably designed as a multi-stage and / or multi-step method. In particular, the method has several method steps.

[0142] Figure 3 A schematic flow chart of the proposed method is shown, which has a plurality of—here six—method steps.

[0143] The individual method steps S1 to S6 can in principle be carried out independently of one another, but can also be carried out in any desired sequence and / or combination.

[0144] In an optional first method step S1, preferably, a calibration of the kitchen appliance 1 is carried out, in particular a calibration of the heating system 20H and / or the heating element 20E is carried out, in particular in subsequent and / or subsequent method steps S2 to S6, the heating temperature HT is determined based on the resistance R of the heating element 20E - exclusively or without using the temperature element 20T - or the heating element 20E can be used as a resistance thermometer.

[0145] The first method step S1 and / or the calibration is preferably carried out autonomously and / or automatically, in particular after starting the kitchen appliance 1 and / or the heating system 20H. In this way, a consistently precise and / or reliable identification of the critical heating state HA is achieved or supported.

[0146] The calibration is preferably carried out by means of a predetermined heating process and / or calibration process, for example in which the heating system 20H delivers a predetermined heat output for a certain period of time.

[0147] In and / or during calibration, preferably the heating system 20H is activated and / or the heating element 20E is supplied with current, in particular so that the heating element 20E heats up and / or the heating temperature HT increases.

[0148] In the calibration and / or for the calibration and / or during the calibration process, the first resistance value R1 of the heating element 20E and the heating temperature value HT1 of the heating element 20E corresponding to the first resistance value R1 are determined and / or assigned to each other - in particular as a reference value. Particularly preferably, the first resistance value R1 as a resistance reference value is assigned to the first heating temperature value HT1 as a heating temperature reference value.

[0149] The first resistance value R1 is preferably determined by voltage and current measurement on the heating system 20H, in particular the heating element 20E, particularly preferably by means of a measuring device 10M, particularly preferably at a first time t1, and / or according to the following equation:

[0150] R1=U1 / I1,

[0151] Here, U1 is the effective value of the voltage in [V] at time t1, and I1 is the effective value of the current in [A] at time t1.

[0152] Preferably, in and / or for the calibration and / or during the calibration process, a plurality of (different) resistance values ​​R1 , R2 of the heating element 20E and corresponding heating temperature values ​​HT1 , HT2 of the heating element 20E are determined and / or assigned to one another.

[0153] Particularly preferably, the second resistance value R2 of the heating element 20E and the second heating temperature value HT2 of the heating element 20E are determined with a time delay or at a second / later time t2 .

[0154] The second resistance value R2 is preferably determined by voltage and current measurement on the heating system 20H, in particular on the heating element 20E, particularly preferably by means of the measuring device 10M, particularly preferably at the second time t2, and / or according to the following equation:

[0155] R2=U2 / I2,

[0156] Here, U2 is the effective value of the voltage in [V] at time t2, and I2 is the effective value of the current in [A] at time t2.

[0157] The temperature coefficient TCR of the heating element 20E is preferably determined and / or estimated using reference values ​​and / or pairs of values, in particular the first resistance value R1, the first heating temperature value HT1, the second resistance value R2 and the second heating temperature value HT2, in particular according to the following equation:

[0158] TCR=[(R2 / R1)-1] / (HT2-HT1).

[0159] As already explained, the heating temperature values ​​HT1 and / or HT2 are preferably determined by means of the temperature element 20T for the purpose of calibration.

[0160] Since the temperature element 20T is not arranged directly on the heating element 20E, the measured temperature MT determined by the temperature element 20T is not equal to the heating temperature HT of the heating element 20E.

[0161] For example, according to Figure 4 The trend of the heating temperature HT and the measuring temperature MT in the figure is exemplified, during the normal heating process the heating temperature HT is higher than the measuring temperature MT, and / or during the heating phase the heating temperature HT is higher than the measuring temperature MT, Figure 4 This heating phase lasts about 50 seconds.

[0162] In this context, the measured temperature MT determined by means of the temperature element 20T is preferably converted and / or corrected by a value determined, in particular empirically, in order to determine the heating temperature HT.

[0163] Preferably - at least during the heating phase - the measured temperature MT corresponds to the heating temperature HT occurring in the past. In particular, the heating temperature value HT1=HT(t1) at time t1 corresponds to the measured temperature value MT(t1+tx) at a later time t1+tx, as Figure 4 Therefore, in order to determine the heating temperature HT - at least during the heating phase - the measured temperature MT can be corrected by the characteristic time constant tx, in particular according to the following equation:

[0164] HT1=MT(t1+tx),

[0165] Here, tx is preferably a time constant determined empirically and having a unit of [s] as a feature.

[0166] Alternatively, the measured temperature MT can be corrected by a predetermined, preferably empirically determined, temperature constant Tx, in particular according to the following equation:

[0167] HT=MT+Tx,

[0168] Here, Tx is preferably a temperature constant determined empirically in units of [° C.] as a feature.

[0169] In other words, in the calibration, preferably the time-shifted / corrected measured temperature values ​​MT(t1+tx) and / or MT(t2+tx) are assigned to the resistance values ​​R1 and / or R2.

[0170] The values ​​required for calibration and / or device-specific values, in particular the characteristic / device-specific time constant tx and / or the characteristic / device-specific temperature constant Tx, and / or the values ​​determined by the calibration, in particular the resistance values ​​R1 and / or R2, the measured temperature values ​​MT(t1+tx) and / or MT(t2+tx), the heating temperature values ​​HT1 and / or HT2 and / or the temperature coefficient TCR are preferably stored or registered electronically or in data form in the kitchen appliance 1, in particular in the data processing device 10R and / or in an external device.

[0171] The calibration is preferably carried out before the preparation process and / or preparation of the food, in particular not during the preparation process and / or during the preparation of the food, and / or under (always) constant conditions, in particular so that different foods and / or preparation processes do not affect the calibration.

[0172] However, in principle, the calibration can also be carried out during the preparation process and / or during the preparation of the food, for example by means of defined heating interruptions or a predetermined calibration recipe. In particular, in the first method step S1 and / or for the calibration, a defined amount of water, for example 100 ml of water, can be heated with a defined (heat) output and / or heated to a defined temperature.

[0173] As explained above, the proposed method allows a device-specific calibration of the heating system 20H and / or the kitchen appliance 1 on site and / or by the user and / or independently of additional (external) measuring devices. However, it is also possible in principle that the calibration is carried out in the delivery state of the kitchen appliance 1 and / or the heating system 20H and / or that the above-mentioned values ​​are already stored in the kitchen appliance 1, in particular in the data processing device 10R in the delivery state of the kitchen appliance 1 and / or on an external device.

[0174] In a second method step S2 , which can also be carried out independently, the resistance R of the heating element 20E and / or the heating temperature HT of the heating element 20E is determined, in particular by means of the measuring device 10M.

[0175] Furthermore, in a second method step S2 , the measurement temperature MT is determined, in particular by means of the temperature element 20T.

[0176] During heating operation of the kitchen appliance 1 and / or the heating system 20H, a measurement / determination of the resistance R, the heating temperature HT and / or the measurement temperature MT is preferably carried out continuously or discontinuously, for example once or twice per second and / or with a sampling rate of 1 Hz or 2 Hz.

[0177] The measured / determined values, in particular the resistance R, the heating temperature HT and / or the measurement temperature MT, are optionally averaged in order in particular to reduce the influence of outliers.

[0178] The values ​​determined in this way are preferably automatically stored and / or evaluated in the kitchen appliance 1 , in particular in the data processing device 10R, and / or in an external device such as a server.

[0179] Figure 4 The normal / usual trend of the heating temperature HT and the measured temperature MT over time when heating water is shown schematically, so that there is no critical heating state HA. The diagram shows that - at least in normal / usual operation - the heating temperature HT and the measured temperature MT run at least substantially parallel to each other and / or with the same slope, wherein the heating temperature HT is greater than the measured temperature MT, in this diagram by about 15°C to 20°C.

[0180] During the heating phase, Figure 4 In the trend / curve shown for approximately 50 seconds, the heating temperature HT and the measuring temperature MT increase at least substantially uniformly and / or linearly.

[0181] When the water starts to boil, the maximum temperature and / or boiling temperature of the water has been reached. Subsequently, a stationary state and / or a cooking state is reached, in which the heating temperature HT, in the present case at a level of about 120° C., and the measuring temperature MT, in the present case at a level of about 100° C., remain at least substantially constant.

[0182] Preferably, in a further and / or third method step S3 , it is checked whether one or more predetermined criteria K1 to K3 are met, in particular for identifying a critical heating state HA.

[0183] In particular, in a further and / or third method step S3 , the heating temperature HT and the measured temperature MT are compared with one another (directly or indirectly), preferably via (filtered) signals and / or metering, particularly preferably on the basis of one or more predetermined criteria K1 to K3 .

[0184] As already explained at the outset, a critical heating state HA may be present if there is a local temperature change of the heating element 20E, in particular a temperature increase and / or a temperature decrease, compared to the other (average) temperature and / or temperature distribution of the heating element 20E.

[0185] For example, a critical heating state HA and / or a local temperature variation exists when the heating temperature HT of the heating element 20E at one location differs by more than 5°C or 10°C from the immediate surroundings of that location, particularly for a period of time greater than one or two seconds.

[0186] Particularly preferably, a critical heating state HA is present if—in particular within a predetermined period of time, for example greater than one or two seconds—one criterion K1 to K3 or several of the criteria K1 to K3 are met.

[0187] Figures 5 to 7 Schematic diagrams are shown in each case with different curves / trends of the heating temperature HT and the measuring temperature MT, wherein one, several or all criteria K1 to K3 are reached at different times and a critical heating state HA is present.

[0188] The first criterion K1 (gradient criterion) is preferably reached when the slope / gradient of the heating temperature HT is greater than the slope / gradient of the measuring temperature MT by a predetermined limit value / threshold value / critical value. In other words, for the first criterion K1, the gradient of the heating temperature HT is compared with the gradient of the measuring temperature MT and / or the difference between the gradients of the heating temperature HT and the measuring temperature MT is formed and compared with a predetermined limit value, for example 2°C / s or 3°C / s.

[0189] The determination of the slope / gradient is preferably performed over a predetermined period and / or sampling period, for example 2 or 3 seconds.

[0190] The second criterion K1 (difference criterion) is preferably reached when the heating temperature HT is greater than the measured temperature MT by a predetermined limit value / threshold value / critical value. In other words, for the second criterion K2, the difference between the heating temperature HT and the measured temperature MT is formed and compared with a predetermined limit value. The second criterion K2 is met if the difference between the heating temperature HT and the measured temperature MT exceeds a predetermined limit value, for example 20° C. or 40° C.

[0191] The third criterion K3 (absolute temperature criterion) is reached when the heating temperature HT or the measured temperature MT (respectively) exceeds a predetermined limit value / threshold value / critical value, for example a measured temperature MT of 80° C. and / or a heating temperature HT of 100° C. In other words, for the third criterion K3, the heating temperature HT and / or the measured temperature MT (respectively) are compared with a predetermined limit value, preferably wherein the limit value of the heating temperature HT is greater than the limit value of the measured temperature MT.

[0192] Figure 5 and Figure 6Each shows an exemplary curve of a heating temperature HT and a measured temperature MT in a kitchen appliance 1 in which the heating plate 20P - for example due to complete evaporation of the water - has local dry areas and / or - for example due to the inclined position of the kitchen appliance 1 - is not completely wetted with water. The heat dissipation of dry areas is not as effective as that of areas wetted with water. Therefore, in Figure 5 and Figure 6 At the end of the curve in , the heating temperature HT of the heating element 20E increases more than the measured temperature MT, thereby reaching the first standard K1.

[0193] In the exemplary embodiment shown, a critical heating state HA exists if all three criteria K1 to K3 are fulfilled.

[0194] Because according to Figure 5 and Figure 6 At the end of the curve of , the slope / gradient of the heating temperature HT is greater than the slope / gradient of the measuring temperature MT for a longer period of time (first criterion K1), and the difference between the heating temperature HT and the measuring temperature MT becomes larger and larger, so that from a certain point in time, the second criterion K2 is also reached. In addition, according to the third criterion K3, both the heating temperature HT and the measuring temperature MT are above the predetermined limit values, and the difference between the heating temperature HT and the measuring temperature MT is greater than ... Figure 5 and Figure 6 Above the predetermined limit value, approximately 80° C. Thus, one or more critical heating states HA can be identified at the end of the curve.

[0195] Figure 7 An exemplary trend / curve of the heating temperature HT and the measured temperature MT is shown, wherein, for example, in the preparation of inhomogeneous food and / or in the case of recipes with individual food pieces - for example meat pieces - a local temperature drop may occur due to a local release of water. In this illustration, the temperature element 20T is thereby locally cooled and the measured temperature MT is thus reduced.

[0196] Since the measured temperature MT then rises more slowly than the heating temperature HT, the second standard K2 is reached after a certain period of time.

[0197] As shown in this exemplary embodiment, a critical heating state HA can be present and / or recognized if a criterion, in this case the third criterion K3 together with the first criterion K1 and / or the second criterion K2, occurs within a certain period of time, for example approximately 10 seconds. Figure 7 In the exemplary embodiment shown, the second criterion K2 and the third criterion K3 are reached only at the end of the curve, within a period of approximately 10 seconds, which represents the critical heating state HA.

[0198] Preferably, different limit values ​​and / or criteria K1 to K3 are used to identify the critical heating state HA, depending on the selected recipe and / or the food to be prepared. In particular, the criteria K1 to K3 and / or the limit values ​​are adjusted recipe-specifically, i.e., depending on the food to be prepared and / or the operating mode of the kitchen appliance 1, in particular the heating system 20H.

[0199] For example, because the heating element 20E heats faster than the thermally slower heating plate 20P, the greater the difference between the heating temperature HT and the measuring temperature MT, the higher the electric power applied to the heating element 20E. In addition, food such as water may limit the maximum heating temperature HT and / or the measuring temperature MT due to the boiling temperature (cooling effect).

[0200] Therefore, different limit values ​​and / or criteria K1 to K3 can be specified for these cases. In particular, if the maximum difference occurring between the heating temperature HT and the measuring temperature MT for the maximum possible electrical power and for different foods or food categories is known, meaningful limit values ​​for the permissible heating states can be defined.

[0201] If / when a critical heating state HA is identified, one or more (countermeasure) measures are taken and / or the operation of the kitchen appliance 1, in particular the operation of the heating system 20H and / or the electric motor 10E, is adjusted - preferably further and / or in a fourth method step S4, in particular automatically - in order to achieve temperature homogenization and, for example, to prevent food from burning.

[0202] Preferably, when / as soon as the critical heating state HA is identified or after the critical heating state is identified, the stirring process by means of the agitator 20R and / or the heating process by means of the heating system 20H is (immediately) implemented, started, stopped and / or regulated, in particular in order to bring the heating temperature HT and the measured temperature MT closer together again and / or make them uniform.

[0203] For example, the stirrer 20R is activated and / or the rotation speed of the motor 10E is increased when / once or immediately after the critical heating state HA is detected. This is particularly effective when preparing uneven food and / or food chunks.

[0204] Additionally or alternatively, the heat output of the heating system 20H can be at least temporarily reduced and / or limited by software. In particular, the target temperature can be reduced for a defined period of time and / or the heating system 20H can be turned off at least temporarily and / or for a defined period of time.

[0205] The preparation process and / or the formulation preparation may also be aborted completely if no good or positive formulation result can be achieved due to the critical heating state HA, for example if the critical heating state HA exists for a predetermined period of time.

[0206] In an optional further and / or fifth method step S5 , it is preferably checked whether the measures taken and / or the adjustment of the operation (mode) of the kitchen appliance 1 , in particular of the heating system 20H, were successful and / or whether the heating temperature HT and the measuring temperature MT are close to each other again.

[0207] Therefore, in a fifth method step S5 , a verification and / or plausibility check of the measures taken is carried out.

[0208] If the heating temperature HT and the measuring temperature MT are not close to one another and / or if no temperature homogenization occurs, the verification and / or plausibility check is preferably negative and / or the measure was unsuccessful.

[0209] For example, if, despite the activation of the stirrer 20R and / or the deactivation of the heating system 20H, there is still no homogenization of the heating temperature HT and the measuring temperature MT and / or a critical heating state HA still exists, this may be a false alarm, for example due to incorrect calibration and / or overly sensitive standards K1 to K3.

[0210] In the case of a false alarm, a recalibration / new calibration can preferably be carried out automatically and / or the first method step S1 can be repeated.

[0211] Additionally or alternatively, the limit values ​​and / or criteria K1 to K3 can be adjusted and / or corrected, in particular reduced in sensitivity. The adjustment of the limit values ​​and / or criteria K1 to K3 is preferably carried out in a further and / or sixth method step S6 .

[0212] For example, when checking the standards K1 to K3 , a large difference between the heating temperature HT and the measurement temperature MT and / or a large difference between the gradient of the heating temperature HT and the gradient of the measurement temperature MT may be defined as allowable.

[0213] It may also be necessary to simultaneously meet other criteria of the criteria K1 to K3 and / or several criteria K1 to K3 in order to thus detect the critical heating state HA.

[0214] In particular in the case of repeated false alarms, the comparison of the heating temperature HT and the measuring temperature MT can also be ignored and / or switched off, for example for the current preparation process.

[0215] In a method variant which can also be performed independently, in addition to the measured temperature MT determined by means of the temperature element 20T, a further measured temperature of the heating system 20H is determined by means of a further temperature element in order to compare the heating temperature HT with a plurality of measured temperatures in order to identify a critical heating state HA.

[0216] In this way, it is (also) possible to identify local temperature changes which occur in the vicinity of one of the temperature elements and which therefore cannot be identified by comparing the heating temperature HT with the measured temperature of the relevant temperature element.

[0217] By means of the proposed kitchen appliance 1 and / or the proposed method, temperature inhomogeneities in the kitchen appliance 1 and / or in the preparation chamber ZR, for example caused by an inclined position of the kitchen appliance 1, by uneven food and / or by locally dry spots on the heating plate 20P, can be detected early and / or precisely and / or safely, in particular without additional supports and / or sensors, and reduced by appropriate countermeasures. In particular, damage to the kitchen appliance 1, for example due to burnt food, can be avoided.

[0218] The various aspects, features and method steps of the present invention may be implemented independently, but may also be implemented in any combination and / or order.

[0219] List of reference numerals:

[0220] 1 Kitchen appliance A center axis

[0221] 10 Abutment HA critical heating state

[0222] 10A Receiver HT Heating Temperature

[0223] 10B Input device HT1 First heating temperature value

[0224] 10C Power line HT2 Second heating temperature value

[0225] 10D Display Device I Current

[0226] 10E Motor I1 first current value

[0227] 10K Communication device I2 Second current value

[0228] 10M Measuring device K1 First standard

[0229] 10N Power Supply Unit K2 Second Standard

[0230] 10R Data processing device K3 Third standard

[0231] 10S Control device M1 First measuring position

[0232] 10U User interface M2 Second measurement position

[0233] 10W Axis MT Measurement Temperature

[0234] 10X First electrical connection R resistance

[0235] 10Y Second electrical connection portion R1 First resistance value

[0236] 20 Container R2 Second resistance value

[0237] 20A Opening S1 First method step

[0238] 20B Bottom S2 Second method step

[0239] 20D Cover S3 Third Method Step

[0240] 20E Heating Element S4 Fourth Method Step

[0241] 20F Heating Surface S5 Fifth Method Step

[0242] 20G Handle S6 Sixth Method Step

[0243] 20H Heating system TCR temperature coefficient

[0244] 20K Contact surface t Time

[0245] 20P Heating plate t1 First time (point)

[0246] 20Q Heating device t2 Second time (point)

[0247] 20R Stirrer tx Time Constant

[0248] 20S Bearing layer T temperature

[0249] 20T Temperature element Tx Temperature constant

[0250] 20W Wall U Voltage

[0251] 20X First electrical connection portion U1 First voltage value

[0252] 20Y Second electrical connection portion U2 Second voltage value

[0253] ZR Preparation Chamber

Claims

1. A method for operating an electric heating system (20H) of a kitchen appliance (1), in, determining the resistance (R) of the heating element (20E) of the heating system (20H) for determining the heating temperature (HT) of the heating element (20E), It is characterized in that Furthermore, a measured temperature (MT) of the heating system (20H) is determined by means of a temperature element (20T) in order to: carry out a calibration of the heating system (20H); and / or to compare the measured temperature (MT) with the heating temperature (HT) in order to identify a critical heating state (HA) of the heating system (20H), the critical heating state being a local temperature change of the heating element (20E).

2. The method according to claim 1, characterized in that The heating element (20E) has or is formed with a first measuring position (M1) for the heating temperature (HT), and the temperature element (20T) has or is formed with a second measuring position (M2) for the measuring temperature (MT).

3. The method according to claim 2, characterized in that The first measuring position (M1) is larger than the second measuring position (M2), and / or the second measuring position (M2) is arranged closer to the preparation chamber (ZR) of the kitchen appliance (1) than the first measuring position (M1).

4. The method according to claim 1, characterized in that: For calibration, the resistance value (R1, R2) of the heating element (20E) and the heating temperature value (HT1, HT2) of the heating element (20E) corresponding to the resistance value (R1, R2) are determined as reference values.

5. The method according to claim 1, characterized in that: For calibration, a plurality of resistance values ​​(R1, R2) of the heating element (20E) and heating temperature values ​​(HT1, HT2) of the heating element (20E) corresponding to the resistance values ​​(R1, R2) are determined to determine a temperature coefficient (TCR) of the heating element (20E).

6. The method according to claim 4 or 5, characterized in that: The one or more heating temperature values ​​(HT1, HT2) are determined by converting a measured temperature value determined by means of the temperature element (20T) into one or more heating temperature values ​​(HT1, HT2).

7. The method according to one of claims 1 to 3, characterized in that The calibration is carried out automatically after starting the heating system (20H) and / or the kitchen appliance (1) and / or for each heating process.

8. The method according to one of claims 1 to 3, characterized in that During operation of the heating system (20H), the difference in the gradient of the heating temperature (HT) and the measured temperature (MT), the difference between the heating temperature (HT) and the measured temperature (MT) and / or the heating temperature (HT) and / or the measured temperature (MT) are compared with one or more limit values ​​to identify a critical heating state (HA) of the heating system (20H).

9. The method according to claim 8, characterized in that The limit value / limit values ​​are adjusted recipe-specifically.

10. The method according to one of claims 1 to 3, characterized in that When the critical heating state (HA) is identified, the operation of the kitchen appliance (1) is adjusted.

11. The method according to one of claims 1 to 3, characterized in that When the critical heating state (HA) is detected, a stirring process and / or a heating process is carried out, started, ended and / or regulated.

12. The method according to one of claims 1 to 3, characterized in that A further measured temperature (MT) of the heating system (20H) is determined by means of a further temperature element in order to compare the heating temperature (HT) with a plurality of measured temperatures (MT) in order to identify the critical heating state (HA).

13. A kitchen appliance (1) for preparing food, the kitchen appliance (1) comprising an electric heating system (20H) for heating a dish (20), in, The heating system (20H) comprises: a heating plate (20P); an electric heating element (20E) for heating the heating plate (20P); a measuring device (10M) for measuring the resistance (R) of the heating element (20E); and a temperature element (20T) for determining a measured temperature (MT) of the heating plate (20P). Therein, the kitchen appliance (1) is designed to implement the method according to one of claims 1 to 12.

14. The kitchen appliance according to claim 13, wherein: The kitchen appliance (1) has a further temperature element for determining a further measured temperature (MT) of the heating plate (20P).

Images