Method for safe operation of combined cooking utensil and combined cooking utensil

Abstract

The invention relates to a method for safe operation of a combination cooking appliance (10) having a cooking chamber (14) and a microwave source (26) with microwave power. A cooking chamber temperature prevailing in the cooking chamber (14) is detected. Convection-related parameters are determined. The detected cooking chamber temperature and convection-related parameters are evaluated to determine a maximum allowable microwave power. The microwave power of the microwave source (26) is limited to a maximum allowable microwave power. Furthermore, a combination cooking appliance (10) is described.

Description

Technical Field

[0001] The present invention relates to a method for the safe operation of a combined cooking appliance. The present invention also relates to a combined cooking appliance. Background Art

[0002] In addition to a heating device for generating hot air, cooking appliances used in professional or large-scale cooking methods usually also have a steam generator for generating steam for cooking the food placed in a cooking chamber of the cooking appliance. The heating device and the steam generator generate a cooking chamber atmosphere in the cooking chamber, which can also be referred to as a cooking chamber climate. The food exposed to the cooking chamber climate is cooked accordingly by the cooking chamber climate, wherein energy is introduced into the food by convection.

[0003] In addition to the heating device and the steam generator, such a cooking appliance may also have a microwave source, which is used to accelerate the cooking process by introducing (additional) energy in the form of microwaves into the cooked product. Usually, cooking appliances with a microwave source in addition to the heating device and the optional steam generator are also referred to as combination cooking appliances.

[0004] It has been found that when there is no cooking product in the cooking chamber, the microwave radiation fed into the cooking chamber interacts primarily with the cooking chamber itself, i.e. it couples into components of the cooking appliance adjoining the cooking chamber, such as the cooking chamber wall or a window in the cooking chamber door. However, the microwave radiation can also be partially absorbed by components that have been added to the cooking chamber, such as cooking accessories or a core temperature probe, in particular the cable of a wired core temperature probe.

[0005] Depending on the material and composition of the components, absorption of the microwave radiation supplied into the cooking chamber may lead to damage to the components. In order to avoid such damage, the prior art proposes to equip the cooking appliance with automatic safety shut-off mechanisms. These automatic safety shut-off mechanisms detect idle operation, i.e. operation of the cooking appliance with an empty cooking chamber, in which case the microwave supply is automatically shut off.

[0006] For example, document DE 10 2004 015 993 A1 discloses a microwave oven which automatically detects idle operation and automatically switches off the device for generating microwaves when idle operation of the cooking appliance has been detected.

[0007] However, it has been found that in some cases, even when the load of the cooking appliance is small or even moderate, that is, when microwave operation is basically allowed, wear or damage of the components of the cooking appliance may occur. Wear or damage is undesirable because the corresponding components must be replaced in advance, which increases costs. Summary of the invention

[0008] In this respect, the object of the present invention is to eliminate the drawbacks of the prior art and to provide a method which allows safe operation of a cooking appliance.

[0009] According to the invention, this object is achieved by a method for safely operating a combined cooking appliance having a cooking chamber and a microwave source with microwave power, the method comprising the following steps:

[0010] - detecting the cooking cabinet temperature prevailing in the cooking cabinet,

[0011] - Determination of convection related parameters,

[0012] - evaluating the detected cooking chamber temperature and convection-related parameters to determine the maximum permissible microwave power, and

[0013] - limiting the microwave power of the microwave source to a maximum permissible microwave power, in particular to a maximum permissible microwave power for the detected cooking chamber temperature and the determined convection-related parameters.

[0014] The invention is based on the basic idea that a combination cooking appliance can be safely operated with a microwave source by limiting the microwave power of the microwave source to a maximum permissible microwave power for determined convection-related parameters and a detected cooking chamber temperature.

[0015] Thus, the maximum permissible microwave power may be lower than a normally possible microwave power (nominal power of the microwave source). Thus, the actual maximum permissible microwave power depends on the detected cooking chamber temperature and the determined convection-related parameters. In other words, the maximum permissible microwave power is specified in terms of the control, i.e. as a function of the detected cooking chamber temperature and the determined convection-related parameters. Thus, the maximum permissible microwave power is variable, in particular during a cooking process, since the cooking chamber temperature and / or the convection-related parameters vary during the cooking process.

[0016] This limits the energy fed into the cooking chamber in the form of microwaves, with the result that less microwave energy can interact with the components of the combined cooking appliance, thereby effectively preventing damage to the components due to microwaves.

[0017] It has been found that microwave energy can be coupled into components of the combination cooking appliance which are present in or delimit the cooking chamber, which heats these components. This leads to increased wear or even damage to the components, which is now effectively prevented so that the combination cooking appliance can be operated reliably and safely. Components present in the cooking chamber are in particular wired temperature probes, which should not exceed a certain temperature.

[0018] If convection occurs at the respective component, i.e. if air flows around the component, the air can be cooled by the latter, which is why the component heats up less. In the case of strong convection or air circulation around the component, more heat energy can be removed than in the case of low convection. If more heat energy can be removed, i.e. if there is more convection, then generally more microwave energy can be fed in under otherwise identical conditions. Therefore, in addition to the cooking chamber temperature, convection-related parameters are also determined and taken into account in the evaluation.

[0019] Thus, two parameters, namely the cooking chamber temperature prevailing in the cooking chamber and the convection-related parameter, influence how high the energy input from the microwaves can still be, from which the maximum permissible microwave power of the microwave source can be determined. Based on these parameters, namely the cooking chamber temperature and the convection-related parameter, the maximum energy that the corresponding component can still absorb without being damaged can be determined or estimated. In this way, the maximum permissible microwave power can be determined for the operating state. The operating state is determined by the cooking chamber temperature and the convection-related parameter.

[0020] In other words, it may be determined what the maximum additional energy input from the microwave source into the component may be such that a threshold or limit value for the temperature of the component is not reached and / or exceeded.

[0021] The actual maximum microwave power that can be introduced and that is limited by the maximum allowed microwave power can thus be closed-loop controlled as a function of the cooking chamber temperature and convection-related parameters.

[0022] In contrast to the safety shut-offs known from the prior art which are merely provided to completely stop the microwave operation, the method according to the invention provides for adjusting or reducing the microwave power of the microwave source when necessary. According to the invention, the (theoretically possible) microwave power of the microwave source, i.e. the nominal power, is therefore (according to the circumstances) reduced to the maximum permissible microwave power, instead of being completely set to zero. A reduction according to the circumstances is understood to be a reduction according to detected or determined parameters, i.e. the cooking chamber temperature and convection-related parameters. Thus, the combination cooking appliance can be operated safely without having to shut down the microwave source. In other words, microwave operation of the combination cooking appliance remains possible.

[0023] The maximum permissible microwave power depends inter alia on the component under consideration. If several components are considered, the maximum permissible microwave power can be selected based on the component that allows the lowest maximum permissible microwave power. This ensures that none of the components under consideration is damaged. In this respect, a global maximum permissible microwave power can be determined.

[0024] In other aspects, the load state of the combination cooking appliance may not play any role in the closed-loop control of the microwave power, so that there is a closed-loop control of the microwave power that is independent of the load of the combination cooking appliance. Instead of using the load as an additional parameter, a convection-related parameter is used, which allows indicating any cooling effect of the components due to convection.

[0025] During the evaluation, a maximum permissible energy input into a component of the combination cooking appliance and / or a maximum permissible temperature of a component of the combination cooking appliance may be taken into account. The maximum permissible microwave power is determined such that the maximum permissible energy input into a component of the combination cooking appliance and / or the maximum permissible temperature of a component of the combination cooking appliance is not exceeded during operation of the microwave source at the maximum permissible microwave power.

[0026] The maximum permissible energy input is understood to be the energy input which can be supplied to a component of the combination cooking appliance without causing the component to be damaged due to absorption of energy or reaching a maximum permissible temperature.

[0027] A maximum permissible temperature is understood to be a temperature which a component of the combination cooking appliance should not exceed, in particular during operation of the microwave source at a maximum permissible microwave power, for example with an empty cooking chamber.

[0028] A component of a combination cooking appliance can be any component or part of the combination cooking appliance within the cooking chamber, such as a cooking chamber wall, a core temperature probe arranged in the cooking chamber, a cable of the core temperature probe, a sensor, a frame, a lamp and / or a viewing window of a cooking chamber door, in particular a window plate. The components of the combination cooking appliance each have a maximum permissible energy input or a maximum permissible temperature, above which damage to the component may occur. Therefore, the maximum permissible energy input is individual for each component. The same applies to the maximum permissible temperature.

[0029] For example, the maximum permissible temperature of the core temperature probe, in particular its cable, is the melting point of the sheath.In the case of an observation window of a cooking chamber door, the transition temperature of a plate, in particular a glass plate, mounted in the observation window can be defined as the maximum permissible temperature.

[0030] By taking into account the maximum permissible energy input and / or the maximum permissible temperature, damage to components during operation can be easily prevented in this way.

[0031] One aspect provides that the cooking chamber temperature is detected by a temperature sensor arranged in the core temperature probe and / or the cooking chamber temperature is detected by a temperature sensor arranged in the cooking chamber of the combined cooking appliance. The temperature sensor can be arranged in the handle part or the measuring part of the core temperature probe. If the core temperature probe is in the rest position, i.e. not inserted into the cooked product, any temperature sensor of the core temperature probe can be used as long as it is not thermally isolated in the rest position. If the core temperature probe is inserted into the cooked product, i.e. in use, the temperature sensor arranged in the handle part can still be used. Alternatively or additionally, a temperature sensor assigned to the cooking chamber but arranged outside the core temperature sensor can be used.

[0032] Furthermore, the determined convection-related parameter may be the rotation speed of the fan wheel, the rotation speed of the fan wheel, the volume per time unit of exchange air in the cooking chamber or the circulation flow rate in the cooking chamber. In particular, the rotation speed of the fan wheel is detected by a sensor, and the rotation speed, the volume per time unit of exchange air in the cooking chamber or the circulation flow rate in the cooking chamber are then determined based on the sensor. However, the rotation speed of the fan wheel detected by the sensor may also be directly taken into account during the evaluation in order to then determine the maximum permissible microwave power based on the rotation speed.

[0033] Another aspect provides that a model, a functional relationship or a table has been determined, in particular empirically, based on which the maximum permissible microwave power is determined as a function of the convection-related parameters and the cooking chamber temperature. The model, the functional relationship or the table is determined in particular for the corresponding component. If several components are involved in limiting the microwave power of the microwave source according to the situation, several models, functional relationships or tables are used accordingly.

[0034] The model, functional relationship or table is preferably based on predetermined data. For example, data have been obtained from a test series in which the influence of a varying microwave power on a cooking chamber with different convection-related parameters and / or different cooking chamber temperatures was analyzed. For different combinations of convection-related parameters and cooking chamber temperatures, a maximum permissible microwave power that can be fed into the cooking chamber without exceeding a maximum permissible energy input into a component of the combination cooking appliance and / or a maximum permissible temperature of a component of the combination cooking appliance can be determined empirically. The data thus obtained can be used as the basis for a model, functional relationship or table on the basis of which a maximum permissible microwave power is determined as a function of the operating state of the combination cooking appliance as a function of the convection-related parameters and the cooking temperature, wherein the maximum permissible microwave power is determined via the convection-related parameters and / or the cooking chamber temperature.

[0035] In particular, at least one predetermined threshold value is provided for the convection-related parameter, exceeding and / or falling below the threshold value leading to a modified dependence of the maximum allowed microwave power. For example, a threshold value can be provided for the rotational speed of the fan wheel, since convection leading to cooling of the components only occurs above a certain rotational speed. At a certain rotational speed of the fan wheel, there may also already be large convection, so that a higher rotational speed will no longer lead to better cooling. In addition, depending on the respective component, different threshold values ​​may be present. The respective threshold values ​​may have been determined empirically. For the sheath of the core temperature probe, in particular its cable, a threshold value of 1,000 revolutions per minute (rpm) can be specified for the rotational speed of the fan. Therefore, the dependence of the maximum allowed microwave power on the rotational speed of the fan as a convection-related parameter is different at rotational speeds below 1,000 rpm than at rotational speeds above 1,000 rpm.

[0036] For example, the maximum permissible microwave power is determined via the detected cooking chamber temperature and a microwave factor that is dependent on at least one predetermined threshold. Thus, the threshold may initially be used to determine the microwave factor, which in turn is used to calculate the maximum permissible microwave power. In particular, the microwave factor is linearly dependent on the at least one predetermined threshold when the value is below the at least one predetermined threshold, while in other cases, i.e. when the at least one predetermined threshold is exceeded, the microwave factor is constant.

[0037] For example, when the microwave factor MW is below a predetermined threshold of the convection-related parameter, factor The dependencies are as follows:

[0038] MW factor =Prop factor *Parmeter convection-relevant +Offset,

[0039] Among them, Prop factor is a scaling factor that has been determined empirically or by simulation, e.g., Parameter convection-relevant is a convection related parameter, and offset is a compensation value for determining the microwave factor when the convection related parameter is 0.

[0040] On the contrary, if a predetermined threshold value of the convection-related parameter is exceeded, the microwave factor MW factor is a constant (const.):

[0041] MW factor =const.

[0042] Furthermore, a temperature limit may be provided, and if the detected cooking chamber temperature reaches the temperature limit, the maximum permissible microwave power is zero. This provides an additional level of safety, since it is ensured that no additional microwave energy is introduced if the cooking chamber temperature is already so high that the maximum permissible temperature of a component of the combined cooking appliance should have been reached or the cooking chamber temperature differs from the maximum permissible temperature of the component by only less than a safety margin. The temperature limit may be 300° C. In this respect, no further microwave energy must be introduced into the cooking chamber when the cooking chamber temperature is above 300° C.

[0043] In particular, it is provided that the microwave source is operated at most with the maximum permissible microwave power, so that the microwaves generated by the microwave source are fed into the cooking chamber. Therefore, the actual maximum microwave power that can be introduced varies according to the situation. The microwave source can be operated at a microwave power lower than the maximum permissible microwave power. In any case, the microwave power output by the microwave source cannot exceed the maximum permissible microwave power.

[0044] The maximum permissible microwave power may be greater than or equal to 0% and less than or equal to 100% of the nominal power of the microwave source. Thus, the full nominal power of the microwave source may be utilized as long as the operating state of the combination cooking appliance (and the power connection of the combination cooking appliance) permits. In other words, the maximum permissible microwave power may be between 0% and 100% of the nominal power of the microwave source, depending on the operating state of the combination cooking appliance, the maximum permissible microwave power being dependent on the detected cooking chamber temperature and convection-related parameters.

[0045] Another aspect provides that the maximum permissible microwave power is determined a plurality of times during the cooking process, in particular regularly or periodically. Thus, the current operating state of the combination cooking appliance is continuously monitored, which results in a (regular or periodic) adjustment of the maximum permissible microwave power.

[0046] The control unit for the combination cooking appliance can take into account the previously determined maximum permissible microwave power when activating the microwave source, in particular when setting the power for the microwave source. As explained above, the maximum permissible microwave power is not necessarily the actual microwave power of the microwave source, but a limit that must not or cannot be exceeded (in terms of control).

[0047] When running a cooking program, it can be provided as follows: The control unit of the combination cooking appliance can also take into account the specifications of the cooking chamber temperature (desired cooking chamber temperature) and the convection-related parameters (desired values ​​of the convection-related parameters). This allows the cooking process to be adjusted, for example the cooking time adjustment, as long as it is determined that the maximum permissible microwave power is lower for a certain period of time, so that it is not possible to shorten the cooking time by introducing additional microwave energy.

[0048] Furthermore, the present invention relates to a combination cooking appliance for cooking a culinary product. The combination cooking appliance comprises a cooking chamber, a microwave source associated with the cooking chamber for feeding microwaves having a specific microwave power into the cooking chamber, a temperature sensor for detecting the temperature of the cooking chamber, and at least one sensor for detecting a convection-related parameter. The combination cooking appliance has an evaluation unit, which is connected to the temperature sensor and the at least one sensor in a signal transmission manner. The evaluation unit is configured to determine the maximum permissible microwave power of the microwave source based on the cooking chamber temperature detected by the temperature sensor and the convection-related parameter determined by the sensor. The combination cooking appliance has a control unit, which is connected to the evaluation unit and the microwave source in a signal transmission manner. The control unit is configured to receive the maximum permissible microwave power determined by the evaluation unit and to limit the microwave power of the microwave source on this basis. The combination cooking appliance is basically configured and arranged to perform the aforementioned method. The corresponding characteristics and advantages of the combination cooking appliance appear in a similar manner.

[0049] As already explained above, the microwave source is driven by the control system so that the actual microwave power is less than or equal to the maximum permissible microwave power, depending on the operating state of the combined cooking appliance. In the event of a change in the operating state, i.e. a change in the cooking chamber temperature and / or convection-related parameters, this therefore also results in a different maximum permissible microwave power.

[0050] In particular, the maximum permissible microwave power is determined a plurality of times during the cooking process, in particular regularly or periodically. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Other advantages and features of the present invention will become apparent from the following description and from the accompanying drawings, to which reference is made, and in which:

[0052] - Figure 1 shows a schematic representation of a combined cooking appliance according to the invention,

[0053] - Figure 2 Shown for Figure 1 The steps of the method according to the invention for safe operation of a combined cooking appliance, and

[0054] - Figure 3 An overview of the maximum allowed microwave power as a function of the cooking chamber temperature and convection related parameters is shown. DETAILED DESCRIPTION

[0055] Figure 1 The combination cooking appliance 10 is shown for cooking a culinary item 12 which has been placed in a cooking chamber 14 of the combination cooking appliance 10 for cooking therein.

[0056] Furthermore, the cooking chamber 14 has a cooking chamber door 16 assigned thereto, which seals the cooking chamber 14 from the environment so that a defined cooking chamber climate can be generated in the cooking chamber 14 for cooking the culinary product 12. The cooking chamber door 16 also has a viewing window 18, which serves to ensure an unobstructed view of the culinary product 12 from the outside during the cooking process. The viewing window 18 is in particular a glass pane.

[0057] A technical compartment 20 is provided, separate from the cooking chamber 14 , in which components are at least partially accommodated which are necessary for generating and regulating the cooking chamber climate, ie the cooking chamber atmosphere, in the cooking chamber 14 or which provide energy for cooking the culinary product 12 .

[0058] In the illustrated embodiment, the combination cooking appliance 10 includes a heating device 22 , a steam generator 24 , a microwave source 26 , and a fan wheel 28 .

[0059] The steam generator 24 and the heating device 22 are at least partially accommodated in the technical compartment 20 and are used in particular to provide a defined cooking chamber atmosphere, in particular a cooking chamber temperature and humidity, in the cooking chamber 14. The cooking chamber atmosphere or cooking chamber climate generated in the cooking chamber 16 is thus defined in particular as a combination of a specific temperature and a specific humidity. In addition, a flow rate and / or a pressure relative to the cooking chamber atmosphere can be provided, provided that the fan wheel 28 is operated accordingly. Basically, the fan wheel 28 can also contribute to the cooking chamber atmosphere or the cooking chamber climate, since it is used to set the convection in the cooking chamber 14.

[0060] The microwave source 26 has at least one antenna 30 facing the cooking chamber 14 to couple the microwaves generated by the microwave source 26 into the cooking chamber 14 and thus apply (additional) energy to the cooking product 12 .

[0061] The combination cooking appliance 10 also has at least one cooking chamber temperature sensor 32, which is arranged to measure the cooking chamber temperature in the cooking chamber 14. The cooking chamber temperature sensor 32 can also be referred to as a cooking chamber sensor. In the exemplary embodiment shown, two cooking chamber temperature sensors or cooking chamber sensors 32 are shown, which can in particular be arranged distributed in the cooking chamber 14. The average value of the cooking chamber temperatures detected by the respective cooking chamber sensors 32 is then used, for example, for further processing.

[0062] Furthermore, a core temperature probe 34 is arranged in the cooking chamber 14 , which has at least one temperature sensor 36 .

[0063] If the core temperature probe 34 is not inserted into the culinary product 12 , the temperature sensor 36 integrated in the core temperature probe 34 can also be used to detect the cooking chamber temperature prevailing in the cooking chamber 14 as an alternative, in particular if the cooking chamber sensor 32 fails.

[0064] Thus, the cooking chamber temperature prevailing in the cooking chamber 14 can be detected using the cooking chamber sensor 32 and / or the core temperature probe 34 , in particular the temperature sensor 36 of the core temperature probe 34 .

[0065] In the illustrated embodiment, the core temperature probe 34 is a wired core temperature probe having a cable 38 arranged in the cooking chamber 14 and exposed to the cooking chamber climate, ie, the cooking chamber temperature, like the core temperature probe 34 itself.

[0066] Furthermore, a sensor 40 is assigned to the fan wheel 28, via which sensor 40 the convection-related parameter can be determined. The sensor 40 can be arranged to measure the rotational speed of the fan wheel 28, which corresponds to the convection-related parameter, since the convection generated by the fan wheel 28 depends on its rotational speed.

[0067] Furthermore, the combination cooking appliance 10 has an evaluation unit 42 which is arranged in the technical compartment 20 and is connected in a signal-transmitting manner to the above-mentioned components, in particular the cooking chamber sensor 32, the core temperature probe 34 and the sensor 40. In this respect, the evaluation unit 42 is configured to receive and evaluate information from the above-mentioned components, namely the cooking chamber temperature and convection-related parameters such as the rotational speed.

[0068] The evaluation unit 42 can also be configured to determine other convection-related parameters based on the rotational speed detected by the sensor 40, such as the rotational speed of the fan wheel 28, the volume of exchanged air per time unit in the cooking chamber 14 or the circulation flow in the cooking chamber 14. Alternatively or additionally, different types of sensors, such as a flow sensor arranged in the cooking chamber 14, can be used to directly detect convection-related parameters other than the rotational speed.

[0069] Typically, the evaluation unit 42 can also be connected in a signal-transmitting manner to the heating device 22 , the steam generator 24 and the microwave source 26 in order to receive information or data from these components.

[0070] The evaluation unit 42 is generally configured and arranged to evaluate the detected cooking chamber temperature and convection-related parameters to determine the maximum permissible microwave power, as will be described below with reference to Figure 2 and Figure 3 More detailed description.

[0071] The evaluation unit 42 is also connected to a control unit 44 in a signal transmission manner, which in turn is connected to at least the microwave source 26 in a signal transmission manner, so that the microwave source 26 can be driven by the control unit 44. In other words, the control unit 44 is configured and arranged to drive the microwave source 26, in particular to drive the microwave source 26 depending on the evaluation result of the evaluation unit 42.

[0072] Therefore, the control unit 44 is arranged to limit the microwave power of the microwave source 26 to a maximum allowed microwave power, as will be explained below.

[0073] The control unit 44 may also be connected to the heating device 22, the steam generator 24 and / or the fan wheel 28 in a signal-transmitting manner, so that the corresponding components can be driven by the control unit 44. For the sake of clarity, these corresponding connections are not shown here.

[0074] In principle, it is conceivable that the evaluation unit 42 and the control unit 44 are designed as a common combined unit, ie a control and / or evaluation unit.

[0075] The combination cooking appliance 10 is configured to carry out a method for safely operating the combination cooking appliance 10 according to the present invention which will be described below.

[0076] In a first step, the cooking chamber temperature prevailing in the cooking chamber 14 is detected (step S1 ). To this end, the cooking chamber sensor 32 and / or one or more core temperature probes 34 measure the cooking chamber temperature prevailing in the cooking chamber 14 .

[0077] The measured cooking chamber temperature is sent to an evaluation unit 42 .

[0078] In the second step, the convection-related parameters are determined (step S2). Figure 1 In the present example embodiment, the sensor 40 measures the rotational speed of the fan wheel 28 as a convection-related parameter.

[0079] The rotation speed is sent to the evaluation unit 42. The evaluation unit 42 can calculate other convection-related parameters based on the rotation speed detected by the sensor, as long as they can be used for the subsequent evaluation.

[0080] In a third step, the detected cooking chamber temperature and convection-related parameters are evaluated by the evaluation unit 42 to determine the maximum permissible microwave power (step S3). During the evaluation, the evaluation unit 42 takes into account the maximum permissible energy input into at least one component of the combination cooking appliance 10 and / or the maximum permissible temperature in at least one component of the combination cooking appliance 10.

[0081] The maximum permissible microwave power is determined such that a maximum permissible energy input into components of the combination cooking appliance 10 and / or a maximum permissible temperature in components of the combination cooking appliance 10 is not exceeded during operation of the microwave source 26 at the maximum permissible microwave power.

[0082] Corresponding components are, for example, the viewing window 18 or the core temperature probe 34 , in particular the cable 38 of the core temperature probe 34 .

[0083] In principle, when determining the maximum permissible microwave power, several components can be considered, each with its own individual maximum permissible microwave power. Then, for example, the component with the lowest individual maximum permissible microwave power is assigned the maximum permissible microwave power to ensure that the components of the combination cooking appliance 10 are not damaged.

[0084] In particular, the evaluation unit 42 uses a model, a functional relationship or a table for the respective components of the combination cooking appliance 10. The model, the functional relationship or the table has been determined in particular based on data that have been empirically determined in advance for the components of the combination cooking appliance 10. Using these data, the model, the functional relationship or the table can then determine the maximum permissible microwave power based on the currently determined convection-related parameters and the currently detected cooking chamber temperature. In other words, the cooking chamber temperature and the convection-related parameters are used as input values, and the maximum permissible microwave power is determined by the evaluation unit 42 using an algorithm or logic.

[0085] The maximum permissible microwave power is greater than or equal to 0% and less than or equal to 100% of the nominal power of the microwave source 26. This depends on the operating state of the combined cooking appliance 10, i.e., on the detected cooking chamber temperature and convection-related parameters such as rotation speed.

[0086] Figure 3 A diagram showing how the maximum allowed microwave power depends on the temperature and convection related parameters of the cooking chamber is shown.

[0087] In the first diagram, the relative detected cooking chamber temperature GT is shown for three different convection-related parameters, namely for a rotation speed of the fan wheel 28 ("LR") of 500 rpm, 750 rpm and >1000 rpm. actual The maximum permissible microwave power (expressed in %) is referred to herein as "available MW".

[0088] In the second diagram, for five different cooking cabinet temperatures GT actual , i.e. for cooking chamber temperatures GT of 270°C, 280°C, 285°C, 290°C and 295°C actual , showing the rotational speed LR relative to the fan wheel 28 rotational speed The maximum permissible microwave power (expressed in %) of a convection-related parameter in the form of (expressed in rpm), referred to herein as "Available MW".

[0089] The third figure shows a three-dimensional diagram showing the temperature of the cooking chamber GT with respect to the detected temperature. actual (expressed in °C) and the speed LR of the fan wheel 28 rotational speed The maximum permissible microwave power (expressed in %) is defined as the maximum permissible microwave power (expressed in %) at a speed (expressed in rpm), referred to herein as "available MW".

[0090] As already explained above, the maximum permissible microwave power is a limitation on the microwave source 26, which does not necessarily correspond to the microwave power actually introduced by the microwave source 26. On the contrary, the theoretically possible microwave power is limited in certain cases, i.e. depending on the cooking chamber temperature and convection-related parameters, such as Figure 3 It can be clearly seen in.

[0091] In particular, it can be clearly seen from this that a temperature limit is set, and when the detected cooking chamber temperature reaches the temperature limit, the maximum allowed microwave power is zero. In the example embodiment shown, the temperature limit is set to 300°C.

[0092] The figures also show the dependency of providing at least one predetermined threshold value for the convection-related parameter, exceeding and / or falling below the threshold value leading to a modification of the maximum permissible microwave power. In the exemplary embodiment shown, the threshold value corresponds to a rotation speed of the fan wheel of 1,000 revolutions per minute (rpm). Above this rotation speed, i.e., the threshold value of 1,000 rpm, the maximum permissible microwave power is 100%, while below this rotation speed, the maximum permissible microwave power decreases with decreasing rotation speed.

[0093] These figures also show that there is a linear relationship between the cooking chamber temperature and the maximum permissible microwave power, which in turn depends on a convection-related parameter, namely the rotational speed.

[0094] In principle, the maximum permissible microwave power can be determined based on the detected cooking chamber temperature and a microwave factor depending on at least one predetermined threshold value. Thus, the maximum permissible microwave power MW can be achieved. max The functional relationship can be expressed as follows:

[0095]

[0096] Among them, GT actual is the detected cooking chamber temperature. In addition, the functional relationship includes the microwave factor MW factor , which describes the linear dependence of the maximum permissible microwave power on the cooking chamber temperature and which itself depends on the convection-related parameters, as already explained in the above figure. Microwave factor MW factor It can be expressed as follows:

[0097] If it is below a predetermined threshold value (1,000 rpm) of the convection-related parameter, the microwave factor MW is obtained. factor The following relationship:

[0098] MW factor =Prop factor *Parmeter convection-relevant +Offset,

[0099] Among them, Prop factor is a scaling factor that has been determined empirically or by simulation, e.g., Parameter convection-relevant The parameter offset is used to determine the microwave factor MW when the convection-related parameter, such as the rotation speed, is 0. factor compensation value.

[0100] On the contrary, if the predetermined threshold value of the convection-related parameter is exceeded (1,000 rpm), the microwave factor MW factor is a constant (const.):

[0101] MW factor =const.=20.

[0102] Furthermore, it is stored in the evaluation unit that if the above functional relationship would result in a value greater than 100, the value of the maximum permissible microwave power is 100, and if the above functional relationship would result in a value less than 0, the value of the maximum permissible microwave power is 0. Thus, as already explained above, it is ensured that the maximum permissible microwave power is between 0% and 100% of the nominal power of the microwave source 26.

[0103] When the evaluation unit 42 has determined the maximum permissible microwave power, this maximum permissible microwave power is then sent to the control unit 44 .

[0104] Then, the controller 44 limits the actual output microwave power of the microwave source 26 to the maximum permissible microwave power (step S4). The microwave source 26 can then be driven or closed-loop controlled accordingly, or a damping element that limits the microwave power can be connected. The microwave power can be open-loop or closed-loop controlled by pulse width modulation, wherein a time interval is set between microwave pulses, such as 20% PWM, in particular a pulse duration of 200ms and a pause of 800ms. The microwave source 26 is then operated so that the microwave power actually output never exceeds the maximum permissible microwave power currently available. The microwave power actually output can also be less than the maximum permissible microwave power, because this is only a limitation of the microwave source 26, and the limitation cannot be exceeded to ensure that the components of the combination cooking appliance 10 are not damaged, such as the sheath of the core temperature probe 34, in particular the cable 38 is not damaged.

[0105] The methods described herein can be used at the beginning of the cooking process or periodically during the cooking process.

[0106] In other words, the maximum permissible microwave power can be determined several times during the cooking process. Initially, the operating conditions of the combined cooking appliance 10, i.e. the cooking chamber temperature and convection-related parameters, are detected several times during the cooking process, in particular regularly or periodically, so that these values ​​can be evaluated based thereon and thus the maximum permissible microwave power can be determined. In this way, it is ensured that both efficiency and safety are maximized, since the theoretically maximum possible microwave power is adjusted according to the situation.

Claims

1. A method for the safe operation of a combined cooking appliance (10) having a cooking chamber (14) and a microwave source (26) with microwave power, the method comprising the following steps: - detecting the cooking chamber temperature prevailing in the cooking chamber (14), - Determination of convection related parameters, - evaluating said detected cooking chamber temperature and said convection-related parameters to determine a maximum permissible microwave power, and - limiting the microwave power of the microwave source (26) to the maximum permissible microwave power.

2. The method according to claim 1, characterized in that The cooking chamber temperature is detected by a temperature sensor (36) arranged in a core temperature probe (34), and / or the cooking chamber temperature is detected by a temperature sensor (32) arranged in the cooking chamber (14) of the combination cooking appliance (10).

3. The method according to claim 1, characterized in that The convection-related parameters determined are the rotational speed of the fan wheel (28), the rotational speed of the fan wheel (28), the volume per time unit of exchange air in the cooking chamber (14) or the circulation flow in the cooking chamber (14).

4. The method according to claim 1, characterized in that: A model, a functional relationship or a table has been determined, in particular empirically determined, based on which the maximum allowed microwave power is determined as a function of the convection-related parameter and the cooking chamber temperature.

5. The method according to claim 1, characterized in that At least one predetermined threshold value is set for the convection-related parameter, exceeding and / or falling below said threshold value leading to a modified dependency of the maximum permitted microwave power.

6. The method according to claim 5, characterized in that The maximum allowed microwave power is determined via the detected cooking chamber temperature and a microwave factor that is dependent on the at least one predetermined threshold value.

7. The method according to claim 1, characterized in that A temperature limit is set, and when the detected cooking chamber temperature reaches the temperature limit, the maximum allowable microwave power is zero.

8. The method according to claim 1, characterized in that The microwave source (26) is operated at most at the maximum allowable microwave power so that the microwaves generated by the microwave source (26) are fed into the cooking chamber (14), and / or the maximum allowable microwave power is greater than 0% of the nominal power of the microwave source (26) and less than or equal to 100% of the nominal power of the microwave source (26).

9. The method according to claim 1, characterized in that: The maximum allowed microwave power is determined a number of times during a cooking operation.

10. A combined cooking appliance (10) for cooking a culinary product (12), the combined cooking appliance (10) comprising a cooking chamber (14), a microwave source (26) associated with the cooking chamber (14) for feeding microwaves having a specific microwave power into the cooking chamber (14), a temperature sensor (32, 36) for detecting the temperature of the cooking chamber, and at least one sensor (40) for detecting a convection-related parameter, The combination cooking appliance (10) has an evaluation unit (42), which is connected to the temperature sensors (32, 36) and the at least one sensor (40) in a signal-transmitting manner. The evaluation unit (42) is configured to determine a maximum permissible microwave power of the microwave source (26) based on the cooking chamber temperature detected by the temperature sensor (32, 36) and the convection-related parameter determined by the sensor (40), and The combination cooking appliance (10) has a control unit (44) which is connected to the evaluation unit (42) and the microwave source (26) in a signal transmission manner, and the control unit (44) is configured to receive the maximum permissible microwave power determined by the evaluation unit (42) and to limit the microwave power of the microwave source (26) on this basis.

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