Method for adjusting microwave power

Abstract

The invention relates to a method for adjusting a microwave power in a cooking appliance (10), comprising the steps of: - specifying a microwave factor; - introducing thermal energy into a cooking chamber (14) of the cooking appliance (10); - determining a heat loss of the thermal energy in the cooking chamber (14); and - adjusting the microwave power based on the microwave factor and the thermal heat loss in the cooking chamber (14). The invention further relates to a cooking appliance (10).

Description

[0001] The invention relates to a method for adjusting microwave power in a cooking appliance. Furthermore, the invention relates to a cooking appliance.

[0002] In professional and commercial kitchens, cooking appliances are used that can cook food in a variety of ways. In addition to traditional methods that use hot air and / or steam to cook the food, modern cooking appliances often also use microwave sources that introduce energy into the food using electromagnetic radiation to (additionally) heat it. Electron tubes (e.g., magnetrons) and semiconductor components can be used as microwave sources.

[0003] In many conventional cooking appliances, the microwave power must be specified by the user for each cooking process. For example, the user can adjust the microwave power in increments between 0% and 100%. Setting the maximum power, or 100%, typically results in the microwave source radiating into the cooking chamber at its full rated power (e.g., 2 kW).

[0004] When setting the microwave power, the user must independently assess the optimal microwave power for the cooking process. Factors such as the load size and the degree of heating must be considered based on their own experience and judgment. Setting the optimal microwave power is therefore very time-consuming and error-prone.

[0005] Setting the microwave power too low can unnecessarily prolong the cooking process. Setting the microwave power too high can lead to drying out, insufficient crust formation, and / or poor energy efficiency.

[0006] The object of the invention is therefore to provide a simple and cost-effective way to prevent incorrect settings of the microwave power during cooking, especially in manual cooking processes, and thus to ensure a good and reproducible cooking result.

[0007] The object is achieved according to the invention by a method for adjusting microwave power in a cooking appliance. The method comprises the following steps: Specifying a microwave factor M; introducing thermal energy into a cooking chamber of the cooking appliance; determining a heat loss of the thermal energy in the cooking chamber; and adjusting the microwave power P MW based on the microwave factor M and the thermal heat loss in the cooking chamber.

[0008] The term "heat removal" refers to a reduction in thermal energy in the cooking chamber, for example, a reduced portion of the thermal energy introduced into the cooking chamber or a reduced portion due to the introduction of (deep-)frozen food. In particular, this can also refer to a portion removed in or from the cooking chamber over a certain period of time. Heat removal can (also) occur due to the absorption of thermal energy by the food being cooked. This is typically the case during an ongoing cooking process, provided no additional food is introduced.

[0009] The basic idea of ​​the invention is to set the microwave power not as an absolute value but as a relative value depending on the heat loss in the cooking chamber.

[0010] This creates a user-friendly and self-regulating system that can respond dynamically to changes in the load and / or the load in the cooking chamber.

[0011] Unnecessarily high microwave power and / or temperatures in the cooking chamber, which can lead to component damage, especially with small loads, are reliably avoided by the heat loss-dependent dosage of the microwave radiation.

[0012] By setting the microwave power as a relative value, it can also be automatically taken into account when regulating the temperature in the cooking chamber. This means that it can be increased or decreased synchronously with the heating output of other components in the cooking appliance, which also contributes to improving cooking quality and / or preventing cooking failures. These components can also introduce energy into the food. For example, they could be an infrared heating element, a hot air source, and / or a steam source, also known as a steam generator.

[0013] In particular, a control and / or evaluation unit is provided which determines the heat loss and adjusts the microwave power P MW based on the microwave factor M and the thermal heat loss in the cooking chamber, in particular the food to be cooked.

[0014] One aspect of the invention provides that the heat removal is characterized by a heat removal power P Abs . The proportion of the heat removal power P Abs that is directly absorbed in the food being cooked is also referred to as the power P GG absorbed in the food. In other words, the focus is not on the total amount of energy removed, but on how much energy or heat is removed in the cooking chamber or from the food in a certain time. It has been shown that the heat removal power is a very suitable reference value for adjusting the microwave power because, on the one hand, it contains important information about the cooking state of the food (colder food generally absorbs thermal energy more quickly than warmer food) and, on the other hand, it can be determined reliably and reproducibly.

[0015] In a preferred embodiment, the microwave power is set to a value that corresponds to the product of the heat dissipation power, in particular the power P GG absorbed by the food being cooked, and the microwave factor (P MW = M*P GG ). This is technically particularly simple to implement and less prone to errors.

[0016] The heat removal, in particular the heat removal power, can be determined based on the average heating power of at least one heating device of the cooking appliance. In this context, it is conceivable that during a cooking process, the cooking chamber temperature is kept at least approximately constant over a period of time. The average heating power generated by the radiating heating device(s) during this period then directly corresponds (excluding any heat losses) to the heat removal power.

[0017] Additionally or alternatively, the heat dissipation or heat dissipation power can also be determined based on a change in temperature and / or humidity in the cooking chamber. Temperature and / or humidity sensors, which are typically present in conventional cooking appliances anyway, can be used for this purpose. Therefore, no additional special hardware is required.

[0018] Ideally, heat loss is determined from a combination of heating activity and temperature and / or humidity changes.

[0019] In a variant of the method, the heat removal or heat removal power is determined based on a heating power introduced into the cooking chamber.

[0020] The heat dissipation of the loaded cooking chamber can be used to determine the heat absorbed by the food by taking into account any heat loss. This heat loss may be a portion of the input heat that heats the cooking chamber shell (hereinafter also referred to as shell loss) and is therefore no longer available for heating the food.

[0021] In simple terms, the heat loss or heat loss power, which is used as a reference value for setting the microwave power, can be the part of the thermal power introduced that is actually absorbed by the food being cooked.

[0022] The power loss taken into account in the method can be a predetermined and / or experimentally determined value.

[0023] In particular, casing losses can be determined in independent tests for each device and / or stored in the cooking appliance's memory. The experimentally determined power loss values ​​can then be easily retrieved from the memory to determine heat loss.

[0024] Of course, more than one power loss value can be stored in the cooking appliance’s memory.

[0025] In particular, it is conceivable that the power loss is a value dependent on the cooking chamber temperature profile. For example, in the case of a heating-up cooking chamber (dynamic case), power loss values ​​are to be expected, since in this case a large proportion of the introduced energy leads to heating of the cooking chamber itself, in particular the cooking chamber shell, and is therefore not available for direct heating of the food being cooked. The power losses depend on the previously set cooking chamber temperature and / or the temperature change. In the stationary or static case, however, i.e. when maintaining a predetermined cooking chamber temperature and assuming a thoroughly heated shell, the thermal power loss is only dependent on the temperature-dependent heat transfer coefficient of the shell and the difference between the cooking chamber temperature and the ambient temperature.

[0026] To take this into account, several power loss values ​​can be stored in the cooking appliance's memory, which can be expected at different cooking chamber temperatures.

[0027] A further aspect of the invention provides that an operating state of a fan wheel or several fan wheels of the cooking appliance is taken into account when determining the heat loss.

[0028] Many modern cooking appliances feature fan rotational changes to homogenize the cooking chamber climate. These changes can lead to altered airflow and thus changes in the measured cooking chamber temperature and / or a change in the heat absorption of the food being cooked. The accuracy of the process can be improved by appropriately considering the operating status of the fan wheel(s), for example, the current direction of rotation and / or changes in direction of rotation.

[0029] In another variant of the process, the microwave factor can be specified by the user. It is conceivable that the user can enter the microwave factor as a numerical value using an input device or select it from a predefined selection. This allows the user to retain control over the cooking process. At the same time, it ensures that there is no risk of significant over- or under-dosing of the microwave power.

[0030] For certain cooking processes, the microwave factor may be fixed because the cooking appliance manufacturer has already (experimentally) determined the optimal microwave factor for the specific food in a prior development process. Such cooking processes can be called intelligent or food-specific cooking processes.

[0031] The invention further relates to a cooking appliance with a cooking chamber and at least one microwave module, which is designed and configured to feed electromagnetic radiation into the cooking chamber in order to cook food placed in the cooking chamber using microwave energy. The cooking appliance has a control and / or evaluation unit, which is designed and configured to execute a computer program with program code means for carrying out a method according to the invention. The advantages discussed for the method apply to the cooking appliance accordingly.

[0032] Further features and advantages of the invention will become apparent from the following description and the drawings, to which reference is made. In the drawings: Fig. 1 a schematic representation of a cooking appliance according to the invention, loaded with a food to be cooked; and Fig. 2 a graphical plot of microwave power curves over a heat removal power.

[0033] In Fig. 1 An embodiment of a cooking appliance 10 according to the invention is shown, which is loaded with a food item 12 to be cooked. The cooking appliance 10 has a cooking chamber 14 and at least one (preferably several) microwave module(s) 16. For simplification, Figur 1 only one microwave module 16 is shown.

[0034] The at least one microwave module 16 comprises a semiconductor microwave source ("Solid State Microwave Generator" - SSMG) and is designed and configured to feed microwave beams into the cooking chamber 14. The microwave beams can have a frequency suitable for heating the food 12 to be cooked in the cooking chamber 14. For example, the frequency is between 2.1 GHz and 2.8 GHz, in particular from 2.4 GHz to 2.5 GHz, preferably approximately 2.45 GHz.

[0035] For feeding into the cooking chamber 14, the at least one microwave module 16 can be equipped with an antenna and a directional coupler (not shown). However, multiple antennas and directional couplers can also be provided per microwave module 16.

[0036] In addition, the at least one microwave module 16 may comprise further components or parts, for example a modulator, an amplifier, a demodulator and / or a controller (not shown).

[0037] In the exemplary embodiment, the cooking appliance 10 is a combination appliance which, in addition to the at least one microwave module 16, has various additional components for cooking the food 12, in particular thermal heating devices 18, such as an infrared heating source 20 and a hot air and / or steam source 22. Of course, this is not to be understood as limiting. Other types of heating devices 18 are also conceivable.

[0038] Furthermore, the cooking appliance 10 comprises at least one temperature sensor 24 with which the cooking chamber temperature can be detected, an optional humidity sensor 25 for detecting humidity in the cooking chamber 14, and a reversibly operable fan wheel 26 with which the cooking chamber atmosphere can be mixed.

[0039] Furthermore, the Figur 1 The cooking appliance 10 shown has an input device 28, for example a touch display, with which a user can make inputs, in particular to select a cooking program (manually) or to set and / or adjust desired cooking parameters.

[0040] In the exemplary embodiment, the cooking appliance 10 also has a control and / or evaluation unit 30 connected to the at least one microwave module 16, as well as a memory 32 in which a computer program with program code is stored. When the computer program is executed by a processor unit (not shown) of the cooking appliance 10, it causes the control and / or evaluation unit 30 to perform a method for adjusting a microwave power. This method is described in more detail below.

[0041] At the start of the process, a food item 12 is placed in the cooking chamber 14 of the cooking appliance 10 or is already in it.

[0042] In a first step of the method, a microwave factor M is specified. This can be done, in particular, by a user input via the input device 28. For example, the microwave factor M is a numerical value that the user enters manually or selects from a plurality of predefined numerical values.

[0043] The user's input can be made, in particular, before the start of a cooking process. Alternatively, input during an ongoing cooking process is also conceivable.

[0044] For certain cooking processes, the microwave factor M may be fixed because the cooking appliance manufacturer has already (experimentally) determined the optimal microwave factor for the specific food in a prior development process. These specific cooking processes may be so-called intelligent or food-specific cooking processes.

[0045] In a second step of the method, thermal energy is introduced into a cooking chamber 14 of the cooking appliance 10 by means of the thermal heating devices 18. Of course, not all of the heating devices 18 described above need to be active simultaneously. For example, it is sufficient if only the infrared heating source 20 or only the hot air and / or steam source 22 introduces thermal energy into the cooking chamber 14.

[0046] In a third step of the method, the control and / or evaluation unit 30 determines a heat loss of the thermal energy in the cooking chamber 14.

[0047] In the exemplary embodiment, the control and / or evaluation unit 30 determines a heat removal power P Abs , which characterizes the heat removal in the cooking chamber 14.

[0048] In simple terms, the control and / or evaluation unit 30 determines, for example, which proportion of the introduced thermal energy is taken in or from the cooking chamber 14 within a certain time.

[0049] In the exemplary embodiment, the heat removal or heat removal power is determined based on an average heating power of the active heating device(s) 18 of the cooking appliance 10. For example, for this purpose (depending on which heating device(s) 18 is / are active), the electrical energy consumed to operate the infrared heating source 20 and / or the hot air or steam source 22 is recorded and evaluated.

[0050] Alternatively, the heat removal or heat removal performance can also be determined based on a temperature and / or humidity change in the cooking chamber 14, which can be detected by means of the temperature sensor 24 or the humidity sensor 25.

[0051] Both variants for determining the heat loss in the cooking chamber 14 can also be combined.

[0052] In the exemplary embodiment, the control and / or evaluation unit 30 determines the power P GG absorbed by the food 12 from the heat absorption power and a power loss Pv of the cooking appliance 10.

[0053] The power loss is the portion of the total thermal power introduced into the cooking chamber 14 that does not directly contribute to the cooking of the food 12 (e.g. casing losses).

[0054] In the exemplary embodiment, the power loss depends on the cooking chamber temperature. It is therefore also taken into account in the process by the control and / or evaluation unit 30 as a function of the cooking chamber temperature. For this purpose, certain power loss values ​​are stored experimentally at various cooking chamber temperatures in the memory 32 of the cooking appliance 10. Depending on the current cooking chamber temperature or the temperature measured by the temperature sensor 24, the appropriate power loss value is retrieved from the memory 32.

[0055] The power P GG absorbed by the food 12 can then be calculated as the difference between the heat removal power P Abs and the power loss Pv, in particular using the formula: P GG = P Abs - PV .

[0056] Furthermore, the operating state of the fan wheel 26 (e.g., a change in rotation direction or stirring power) can also be explicitly considered when determining the heat dissipation or heat dissipation power. However, the operating state of the fan wheel 26 can also be considered indirectly, in particular through the influence of the fan wheel operation on the heat dissipation in the cooking chamber 14. The fan wheel 26 can swirl a layer of air surrounding the food 12, thus creating a so-called microclimate in the cooking chamber 14.

[0057] In a fourth step of the method, the control and / or evaluation unit 30 sets the microwave power P MW based on the microwave factor M and the thermal heat loss or heat loss power in the cooking chamber 14, in particular the power absorbed by the food 12.

[0058] In the exemplary embodiment, it calculates a value according to the formula P MW =M*P GG which corresponds to a product of the power P GG absorbed by the food 12 and the microwave factor M and adjusts the power of the at least one microwave module 16 so that it radiates microwaves with the calculated power value into the cooking chamber 14.

[0059] Fig. 2 shows schematically possible microwave power curves over the heat removal power for different microwave factors.

[0060] In the exemplary embodiment, the microwave power P MW is directly proportional to the power P GG absorbed by the food 12. The proportionality factor is the microwave factor M. For example, the following formulaic relationship may exist: P MW =M*P GG =M*P Abs -M*PV . As already explained above, P Abs is the thermal power absorbed in the cooking chamber 14, and PV is the power loss.

[0061] In this case, the gradient corresponds to the Fig. 2 The microwave power curves shown correspond to the microwave factor.

[0062] In Fig. 2 A first microwave power curve 34 is shown, in which the microwave factor is 1. A second microwave power curve 36 is shown, in which the microwave factor is 0.5. In a third microwave power curve 38 shown, the microwave factor is 0.25, in a fourth microwave power curve 40 shown, the microwave factor is 0.1, and in a fifth microwave power curve 42 shown, the microwave factor is 0.05.

[0063] As shown by Fig. 2 As can be seen, the user can determine how quickly or strongly the microwave power increases during a cooking process by specifying the microwave factor M.

[0064] Of course, this increase cannot continue indefinitely. Fig. 2 the microwave power curves are limited upwards by the nominal power 44 of at least one microwave module 16 (for example 2 kW).

[0065] Even downwards, as in Fig. 2 As shown, a threshold value 46 for the microwave power may be provided. Thus, it is conceivable that the at least one microwave module 16, for technical and / or energy efficiency reasons, only feeds microwaves into the cooking chamber 14 when the lower threshold value 46 is exceeded.

[0066] In the exemplary embodiment, this can be implemented in practice by activating the at least one microwave module 16 only when the product of the microwave factor and the heat dissipation power results in a value that is above the threshold value 46. Alternatively, microwave powers below the threshold value can also be realized by suitable timing of the microwave module 16.

Claims

1. A method for adjusting a microwave power in a cooking appliance (10), comprising the steps of: - specifying a microwave factor; - introducing thermal energy into a cooking chamber (14) of the cooking appliance (10); - determining a heat loss of the thermal energy in the cooking chamber (14); and - adjusting the microwave power based on the microwave factor and the thermal heat loss in the cooking chamber (14).

2. The method according to claim 1, wherein the heat removal is characterized by a heat removal power.

3. The method according to claim 2, wherein the microwave power is set to a value corresponding to a product of the heat removal power and the microwave factor.

4. Method according to one of the preceding claims, wherein the heat loss is determined based on an average heating power of at least one heating device (18) of the cooking appliance (10).

5. Method according to one of the preceding claims, wherein the heat loss is determined based on a temperature change in the cooking chamber (14).

6. Method according to one of the preceding claims, wherein the heat loss is determined on the basis of a heating power introduced into the cooking chamber (14) and a power loss of the cooking appliance (10).

7. The method according to claim 6, wherein the power loss is a predetermined and / or experimentally determined value.

8. The method according to claim 7, wherein the value can be retrieved from a memory (32) of the cooking appliance (10).

9. Method according to one of claims 6 to 8, wherein the power loss is a value dependent on the cooking chamber temperature.

10. Method according to one of the preceding claims, wherein an operating state of at least one fan wheel (26) of the cooking appliance (10) is taken into account when determining the heat loss.

11. Method according to one of the preceding claims, wherein the microwave factor can be specified by a user or is specified by an appliance manufacturer for certain cooking processes.

12. The method according to claim 11, wherein the microwave factor specified by the device manufacturer can only be adjusted to a limited extent by a user.

13. Method according to one of the preceding claims, wherein the microwave power is set as a relative value depending on the heat loss in the cooking chamber.

14. Method according to one of the preceding claims, wherein the microwave power reacts dynamically to changes in the load quantity and / or the load in the cooking chamber.

15. Cooking appliance with a cooking chamber (14), at least one microwave module (16) which is designed and configured to feed electromagnetic radiation into the cooking chamber (14) in order to cook a food item (12) placed in the cooking chamber (14) by means of microwave energy, and a control and / or evaluation unit (30) which is designed and configured to execute a computer program with program code means for carrying out a method according to one of claims 1 to 14.

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