DE102016114708A1 - Method for operating a cooking appliance and cooking appliance - Google Patents

Abstract

The present invention relates to a method for operating a cooking appliance (1) and a cooking appliance (10). The cooking appliance (10) comprises a cooking chamber (2) and a high-frequency generator (3). In the cooking chamber (2), food (4) is heated by means of the high-frequency generator (3) by high-frequency radiation. In this case, high-frequency radiation of a first frequency range (15) and a second frequency range (25) is transmitted over a defined period of time into the cooking chamber (2). Due to a frequency-dependent penetration depth (6) of the high-frequency radiation in the first frequency range (15), the food (4) is heated substantially continuously by the power of the high-frequency radiation, so that the food (4) is cooked. Due to a frequency-dependent penetration depth (6) of the high-frequency radiation in the second frequency range (25), the food (4) is deliberately heated close to the surface by the power of the high-frequency radiation, so that a surface structure of the food (4) is changed characteristically and, in particular, browned.

Description

The present invention relates to a method for operating a cooking appliance and a cooking appliance. The cooking appliance comprises at least one cooking chamber and at least one high-frequency generator. In the cooking chamber, food is heated by high frequency radiation by means of the high frequency generator.

Cooking appliances for heating food to be cooked by means of high-frequency radiation and in particular Mikrowellengargeräte offer the advantage of specifically heating the food, without the entire cooking chamber must be heated. This can save a lot of energy and at the same time a very good cooking result can be achieved.

However, if the surface of the food to be browned, usually also in Mikrowellengargeräten the oven must be heated with a conventional auxiliary heater. Usually, the oven is heated to temperatures above 135 ° C, so that the desired browning reactions and, for example, the Maillard browning can take place.

However, this has the consequence that a lot of energy must be invested in the heating of the cooking chamber components. This energy is usually not directly for heating the food available, but is delivered to the food with only a very low efficiency of about 10%. The rest is lost regularly.

In addition, the cooking chamber components are heavily loaded by the thermal cycling and in particular by the simultaneous contact with the food. For example, loss of gloss and discoloration or detachment occur on the cooking chamber walls. Therefore, high demands are placed on the choice of materials for the cooking chamber and its surrounding environment, so that the usable materials are often very expensive.

Another disadvantage is that residues that have escaped from the food after the browning process are in some cases very firmly baked on the walls of the cooking chamber and on the accessories. This often requires a very tedious or energetically consuming cleaning.

It is therefore the object of the present invention to improve the browning of food in cooking chambers of cooking appliances. In particular, the aforementioned disadvantages should be overcome.

This object is achieved by a method having the features of claim 1 and by a cooking appliance having the features of claim 14. Preferred developments of the invention are subject of the dependent claims. Further advantages and features of the present invention will become apparent from the description of the embodiments.

The inventive method is used to operate a cooking appliance with at least one cooking chamber and with at least one high-frequency generator. In the cooking chamber of the cooking appliance, food is heated by means of the high-frequency generator by high-frequency radiation. In this case, high-frequency radiation of at least one first frequency range and at least one second frequency range is transmitted over a defined period of time into the cooking chamber. In this case, due to a frequency-dependent penetration depth of the high-frequency radiation in the first frequency range, the food to be cooked is heated substantially continuously and preferably continuously through the power of the high-frequency radiation, so that the food is cooked. Due to a frequency-dependent penetration depth of the high-frequency radiation in the second frequency range, the food to be cooked is heated by the power of the high-frequency radiation in a targeted manner near the surface. Characterized a surface texture of the food is changed characteristically and especially browned.

The method according to the invention offers many advantages. A significant advantage is that a characteristic change in the surface texture of the food and preferably a browning can be done without an energy-consuming heating of the entire cooking chamber. With the technology according to the invention, both the inside of the food can be cooked (already known) and also tanned on the surface (new) in a cold to warm food oven, as known from pure microwave ovens. Through the use of high-frequency radiation in the second frequency range, the surface of the food can be specifically supplied with power, so that it itself is heated much more heated than the oven and thus browned. This achieves a considerable energy saving. In addition, no expensive cooking chamber components must be used, since no unfavorable thermal cycling takes place. Furthermore, a consuming to be cleaned contamination of the cooking chamber can be avoided because fat splash or the like can not burn on the cold cooking space walls ..

Another advantage of the method according to the invention is that the targeted near-surface heating an undesirable cooking of Gargutinneren is avoided during tanning. In conventional browning in a heated cooking space, however, it can easily happen that the food is over-cooked by the tanning inside.

In the context of the present invention, the penetration depth of the high-frequency radiation is understood in particular to mean a distance from the surface of the food to a region in the food to be cooked with a defined intensity of the high-frequency radiation. It is also possible that the penetration depth is understood to be a distance starting from the surface of the cooking product, via which a defined decrease in the intensity of the high-frequency radiation occurs. Under the penetration depth, the distance from the surface of the food to an area in the food to be cooked with a maximum or a mean maximum power absorption by the food is understood.

Preferably, the penetration depth of the high-frequency radiation in the first frequency range is at least ten times, and more preferably by a factor of 100, higher than the penetration depth of the high-frequency radiation in the second frequency range. It is also possible that the penetration depth in the first frequency range is at least by a factor of two and in particular by a factor of five higher than the penetration depth in the second frequency range. It can also be provided that the penetration depth of the high-frequency radiation in the first frequency range is at least a factor of 1000 higher than the penetration depth in the second frequency range. By means of such penetration depths, a particularly favorable change of the surface structure can take place in the second frequency range and a particularly tasty cooking in the first frequency range.

The penetration depth of the high-frequency radiation in the first frequency range is preferably at least 1 mm and particularly preferably at least 10 mm. It is also possible and advantageous that the penetration depth in the first frequency range is at least 2 cm and in particular at least 5 cm and particularly preferably 10 cm or more. Through such penetration depths, a favorable distribution of the absorbed power to the volume of the product to be cooked can be achieved. The consequent power consumption per unit volume of the food is thus relatively small, which leads to a desired cooking for the heating, but not to a browning on the surface of the food. Such penetration depths thus allow cooking without undesirable influence on the browning process.

The penetration depth of the high-frequency radiation in the second frequency range is preferably at most 1 mm and particularly preferably at most 500 μm. It is also possible that the penetration depth of the high-frequency radiation in the second frequency range is a maximum of 10 mm and preferably a maximum of 5 mm. Particularly preferably, the penetration depth in the second frequency range is a maximum of 250 μm, in particular a maximum of 100 μm. The penetration depth in the second frequency range can also be a maximum of 50 μm or even a maximum of 10 μm or less. It is possible that the penetration depth in the second frequency range is several microns or less.

Through such penetration depths, a targeted power supply can take place in a considerably smaller volume of food to be cooked than in the case of a power supply in the first frequency range. A power consumption per unit volume is thus particularly large, which leads to a browning of the locally heated areas, without a cooking takes place outside the penetration depth. This allows a particularly advantageous browning, without the desired cooking process is undesirable influenced.

The first and / or second frequency range comprises in particular at least one frequency. It is possible that one frequency range comprises only one frequency. Preferably, a frequency range includes a plurality of frequencies.

In an advantageous embodiment, a lowest frequency of the second frequency range is at least twice as large as a highest frequency of the first frequency range. By such a determination of the frequencies, the different penetration depths can be realized particularly well. It is also possible that an average frequency of the second frequency range is at least twice as large as an average frequency of the first frequency range. The lowest frequency in the second frequency range is preferably twice as high as the highest frequency of the high frequency radiation of a household microwave oven.

The first and second frequency ranges are in particular in the frequency range of microwave radiation. The first and second frequency ranges are in particular outside the frequency range of infrared radiation.

It is preferred that the first frequency range is between 400 MHz and 2600 MHz. Such a frequency range is particularly suitable for cooking food and also offers an advantageous penetration depth to cook the interior of the food. It can be provided that the first frequency range extends only over part of the range between 400 MHz and 2600 MHz and, for example, between 902 MHz and 928 MHz. However, it is also possible that the first frequency range extends over the entire range between 400 MHz and 2600 MHz. It is possible that two or more or a plurality of first frequency ranges are provided, which are in the range between 400 MHz and 2600 MHz. The first frequency range may also include higher and / or lower frequencies.

It is also preferable that the second frequency range is between 4.5 GHz and 250 GHz. The high frequency radiation in such a second frequency range offers a particularly low penetration depth. So a particularly effective browning is possible without the interior of the food is affected. It can be provided that the second frequency range extends only over part of the range between 4.5 GHz and 250 GHz. There may also be two or three or a plurality of second frequency ranges between 4.5 GHz and 250 GHz. It is also possible that the second frequency range extends over the entire range between 4.5 GHz and 250 GHz. The second frequency range may also include higher and / or lower frequencies.

In all embodiments, it is particularly preferred that the first frequency range lies in at least one ISM band. It is also particularly preferred that the second frequency range lies in at least one ISM band. In particular, at least one ISM band is provided for the frequency ranges. As a result, the process can be technically implemented particularly inexpensively and inexpensively. The first and / or second frequency range may also extend only partially over at least one ISM band in each case.

The first frequency range preferably extends over an ISM band between 433.05 MHz and 434.79 MHz and / or over an ISM band between 902 MHz and 928 MHz and / or over an ISM band between 2400 MHz and 2500 MHz. By such frequency bands, a penetration depth can be realized in the first frequency range, which extends as far as possible into the food. In addition, the ISM band between 2400 MHz and 2500 MHz has the advantage that in certain regions it is frequently used for microwave cooking appliances.

The second frequency range is preferably in an ISM band between 5.725 GHz and 5.875 GHz and / or in an ISM band between 24 GHz and 24.25 GHz and / or in an ISM band between 61 GHz and 61.5 GHz and / or in an ISM band between 122 GHz and 123 GHz and / or in an ISM band between 244 GHz and 246 GHz. Such frequencies offer a favorable penetration depth and thus enable a targeted tanning.

In all embodiments, it is preferred that the high-frequency radiation in the second frequency range is generated and / or transmitted independently of the high-frequency radiation in the first frequency range. As a result, cooking and browning can be done independently, so that particularly tasty cooking results can be achieved. Thus, for example, it can be prevented that the food is undesirably cooked further during the browning and, for example, dries out. If, however, the option is selected, at the same time as tanning and cooking, the cooking time can be reduced considerably without sacrificing quality.

In particular, there is a time-independent generation and / or transmission of the high-frequency radiation in the respective frequency ranges. In particular, the defined periods for generating and / or transmitting the high-frequency radiation in the respective frequency range are determined independently of each other. The defined periods may overlap at least partially. It is also possible that the defined periods are temporally separated from each other and do not overlap. Thus, the high frequency radiation in the two frequency ranges at least temporarily be sent out at the same time or in exchange.

For example, the food to be cooked first gently in the first frequency range. Subsequently, a browning in the second frequency range can take place. It can continue to be cooked during the tanning in the first frequency range. For example, it is also possible first to brown in the second frequency range. At the same time or subsequently, it is possible to cook in the first frequency range. The previous browning offers the advantage that roasting aromas already exist during cooking.

It may also be provided for repeated cooking and / or browning during the preparation process. It is also possible that high-frequency radiation in the respective frequency ranges is transmitted repeatedly at the same time and / or repeatedly alternatingly. A plurality of cycles may be carried out in which the high-frequency radiation of the respective frequency ranges is transmitted in a defined sequence. For example, the number of cycles and / or the sequence in the cycles may be predetermined by at least one operating program.

Particularly preferably, the power of the high-frequency radiation in the second frequency range is set independently of the power of the high-frequency radiation in the first frequency range. In this case, the intensity of the change in the surface structure of the food or the intensity of cooking in the interior of the food is preferably adjusted by the power of the high-frequency radiation. In particular, a measure of the change in the surface structure of the food can be set substantially independently of a degree of cooking. By means of an independently adjustable power of the high-frequency radiation for the respective frequency range, browning and cooking can be influenced particularly well separated from each other. So can against At the end of a preparation process, for example, a tanning with a high power of the high-frequency radiation done, while cooking is done only at a very low power. This avoids overcooking and at the same time prevents the interior of the food from cooling down. Preferably, at least one frequency of the high-frequency radiation and / or a duration and / or a time of transmission of the high-frequency radiation in the first frequency range is adjustable independently of the second frequency range.

Preferably, the high-frequency generator for generating and / or transmitting the high-frequency radiation of the first and second frequency range comprises at least one high-frequency unit. The high-frequency unit preferably comprises the components necessary for generating and / or transmitting the high-frequency radiation of the respective frequency range. Preferably, the high-frequency units for each channel provided in the frequency ranges comprise at least one transmitting device with a suitable antenna. By way of example, a high-frequency unit in each case comprises at least one frequency generator and / or at least one amplifier device and / or at least one transmission device with at least one antenna. By two high-frequency units power and / or frequency and / or duration and / or time of generating or transmitting the respective frequency ranges can be adjusted particularly well independently.

In particular, a radio-frequency unit is suitable and designed to generate and / or transmit only the radio-frequency radiation in the first frequency range. In particular, another high-frequency unit is suitable and designed to generate and / or transmit only the high-frequency radiation in the second frequency range. In particular, high-frequency units are designed such that they can not generate and / or send out the high-frequency radiation of the respective other frequency range.

However, it is also possible that the high-frequency generator comprises only one high-frequency unit which is suitable and designed to generate and / or transmit the high-frequency radiation in the first and second frequency ranges. In particular, the one radio-frequency unit is then suitable and designed to adjust the power and / or frequency of the radio-frequency radiation and / or the time and / or the duration of the transmission of the radio-frequency radiation in the first and second frequency range independently of each other. However, it can also be provided that the high-frequency unit can only generate the high-frequency radiation of the first and second frequency ranges offset in time and in particular not at the same time.

In an advantageous embodiment, at least one characteristic variable for a wave property of a high-frequency radiation reflected from the cooking chamber is detected. In particular, a reflection of the radio-frequency radiation previously sent into the cooking chamber is detected. The reflected and detected high-frequency radiation is in particular compared with at least one characteristic variable for a wave property of the high-frequency radiation transmitted into the cooking chamber. On the basis of the comparison, preferably at least one parameter for the state of preparation of the cooking product is determined. The characteristic variable for a wave property is in particular a frequency and / or wavelength and / or amplitude and / or phase. Preferably, the characteristic quantity is detected as a function of time and / or frequency. Particularly preferably, at least one scatter parameter is detected and evaluated for the comparison of emitted and reflected high-frequency radiation.

For detecting the necessary quantities and in particular for detecting the scattering parameter and for determining the characteristic, at least one monitoring device is preferably provided. The monitoring device preferably comprises at least one receiving unit for receiving the reflected high-frequency radiation in the two frequency ranges. In particular, the monitoring device is operatively connected to the high-frequency generator and / or a control device of the cooking appliance.

The parameter for the state of preparation of the food to be cooked is, in particular, a browning state and / or a state of cooking and / or a moisture content and / or a mass of the food. Such characteristics are particularly meaningful and can be used particularly well for monitoring the preparation process or for controlling automatic programs.

It is also possible that the parameter for the state of preparation of the food is sensory detected. Preferably, at least one sensor means is provided for this purpose, for example at least one thermometer. It is also possible that at least one gas sensor is provided for detecting products of a browning reaction. It may also be provided at least one color sensor for monitoring the browning state. It is also possible that at least one camera is provided for monitoring the browning state.

The comparison of the emitted and the reflected high-frequency radiation takes place especially taking into account the frequency. On the basis of a frequency-dependent comparison in the first frequency range, a parameter for the cooking state of the food is preferably determined. Because of the great penetration depth in the first frequency range, information about the state of the cooking inside the food can be determined particularly well. Based on a frequency-dependent comparison in the second frequency range, preferably at least one parameter for the browning state of the food is determined. Due to the particularly low penetration depth in the second frequency range, information about the surface structure and in particular about the browning state of the food can be determined particularly well.

The time of transmission and / or the duration of the defined periods and / or the power of the high-frequency radiation in the first frequency range and / or the second frequency range are preferably set as a function of the parameter. The setting includes in particular a controlling and / or rules. It is also possible and preferred that the time of transmission and / or the duration of the defined periods and / or the power of the radio-frequency radiation in the first frequency range and / or in the second frequency range is set depending on at least one user preference and / or at least one operating program. This provides an optimal adaptation of cooking and browning to the particular state of preparation of the food. As a result, for example, too strong or too weak browning or overcooking is effectively counteracted.

The adjustment preferably takes place taking into account the parameter by at least one monitoring device and / or control device operatively connected to the high-frequency generator. This allows an automated setting and a determination of the parameter without the user's intervention.

It is possible that, in addition to the power of the high-frequency radiation, the food to be cooked is heated in a targeted manner near the surface with at least one thermal heating source. It is possible that the food to be cooked with the thermal heat source is additionally heated substantially continuously and preferably continuously. The thermal heat source is designed in particular as an electrical resistance heating source. For example, the thermal heat source comprises a top heat and / or bottom heat and / or a grill heat source and / or a hot air source and / or circulating air heating. Support by the thermal heat source is a good complement to heating by the high frequency radiation. Compared to a sole tanning with a thermal heat source, the method according to the invention also offers energy advantages in this embodiment.

The cooking appliance according to the invention comprises at least one cooking chamber and at least one high-frequency generator. In the cooking chamber, food can be heated by means of the high-frequency generator by high-frequency radiation. In this case, the high-frequency generator is suitable and designed to transmit high-frequency radiation of at least a first frequency range and at least a second frequency range over a defined period of time in the cooking chamber. Due to a frequency-dependent penetration depth of the high-frequency radiation in the first frequency range, the food to be cooked is substantially continuously and preferably continuously heated by the power of the high-frequency radiation, so that the food is cooked. Due to a frequency-dependent penetration depth of the high-frequency radiation in the second frequency range, the food to be cooked can be heated by the power of the high-frequency radiation near the surface. In this case, a surface structure of the food is characteristically changeable. In particular, the food is browned thereby.

The cooking appliance according to the invention also offers many advantages. Particularly advantageous is the high frequency generator, with which the food can be selectively browned on the surface without being cooked inside. By tanning by means of high-frequency radiation can be dispensed with a costly and energy-consuming heating of the entire cooking chamber.

Particularly preferably, the high-frequency generator comprises at least two independently operable high-frequency units. In this case, the radio-frequency radiation of the first frequency range can be generated and / or emitted with at least one radio-frequency unit. With at least one other radio-frequency unit, the radio-frequency radiation of the second frequency range can preferably be generated and / or transmitted. In particular, the high-frequency units are simultaneously and / or independently operable. In particular, the power and / or frequency and / or duration and / or time of the generated and / or emitted high-frequency radiation in the first and / or second frequency range are independently adjustable.

Particularly preferably, the cooking appliance is suitable and designed to be operated by the method according to the invention.

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

In the figures show:

1 a highly schematic representation of a cooking appliance according to the invention; and

2 a highly schematic frequency-dependent course of a penetration into food.

The 1 shows an inventive cooking appliance 1 , which is preferably operated by the method according to the invention. The cooking appliance 1 includes one through a door 21 lockable cooking space 2 , In the oven 2 Here is an exemplary food 4 ,

The cooking appliance 1 is via an operating device 11 operable. About the operating device 11 For example, different operating modes or program operating modes and / or automatic functions can be set. The operating device 11 is equipped with a display device via which various information and / or signals about the operation and the preparation process can be displayed.

For the preparation of the food 4 includes the cooking appliance 1 a high frequency generator 3 for generating and emitting high-frequency radiation in the oven 2 , In this case, the high-frequency generator, for example, a solid-state high frequency generator 3 which in particular comprises a power semiconductor and a suitable antenna and amplifier device. In other embodiments, the high frequency generator 3 comprise at least one magnetron or be designed as such.

The high frequency generator 3 here includes two high-frequency units 13 . 23 with suitable antennas for the channels provided in the frequency ranges. The radio frequency units 13 . 23 preferably transmit via at least one channel in the respective frequency range. Each radio frequency unit comprises 13 . 23 preferably at least one high frequency module for each channel. A high-frequency module comprised the means necessary for transmitting the channel, for example at least one antenna.

The one radio frequency unit 13 is suitable and designed to generate high-frequency radiation in a first frequency range and into the cooking chamber 2 send out. Here, the first frequency range is set here so that a frequency-dependent penetration depth of the high-frequency radiation to a power input inside the food 4 leads. This is how the food is cooked 4 continuously heated by the power of the high-frequency radiation and thus cooked very evenly.

The second radio frequency unit 23 is here suitable and designed to generate high-frequency radiation in a second frequency range and in the oven 2 send out. Here, the second frequency range is set so that a targeted near-surface power input into the food 4 is achieved. This will cause the food to be cooked 4 heated so much at the surface, that a surface structure is changed characteristically and in particular browned.

It is possible that a radio frequency unit 13 and in particular the radio frequency unit 13 is designed for the first frequency range with at least one magnetron. The other radio frequency unit 23 is then preferably equipped with a solid state frequency generator with at least one power semiconductor. It can also both high frequency units 13 . 23 be equipped with a magnetron or with a solid state frequency generator.

The two radio frequency units 13 . 23 preferably have specialized antennas for the respective frequency ranges or channels. It is also possible that a broadband antenna is used. It is preferred that the radio frequency units 13 . 23 each working in a whole frequency band and not only in each case an assigned frequency.

Preferably, several channels are used, which are provided by at least one high-frequency module in each case. Accordingly, several antennas in or on the cooking chamber 2 arranged. This includes a power unit 13 . 23 or a high-frequency module for each channel, preferably at least one component of the following components: a voltage-controlled frequency generator (VCO), a voltage-controlled preamplifier (VCA), a high-frequency power amplifier (PA), a phase shifter, a (bidirectional) coupler, a circulator, an IQ (de) modulator, an antenna. It is also possible that at least one of the components is provided for a plurality of channels of a frequency range or an entire frequency range.

The two frequency units 13 . 23 are independently operable here. As a result, the generation and emission of the high-frequency radiation for the first and second frequency ranges can be carried out independently of one another. In addition, the power of the high frequency radiation for each frequency range can be tailored. Also, the timing and / or the duration of the generation or the transmission for the first and second frequency range can be set individually. The radio frequency unit 23 for tanning is preferably alternating and / or simultaneously with the radio frequency unit 13 operated for cooking.

The decoupling of cooking and browning many advantages for the preparation of the food 4 , A particular advantage is that browning is essentially possible without cooking the food inside. Likewise, it can also be cooked and browned at the same time, so that the preparation time can be considerably shortened. By independently adjusting the power input, the intensity of the tanning can be adjusted individually and free of the strength of the cooking state. For example, a strong browning with only slightly cooked interior of the food 4 be combined. But it can also be a completely cooked food 4 be achieved with a slight tan.

In contrast to the present invention is baked or fried in classic cooking in the heated cooking chamber with a certain and often constant cooking chamber temperature. The oven temperature is typically between 140 and 220 ° C, rarely lower or higher. That is, in the terminology of tanning and cooking done at these cooking temperatures always both at the same time. The food moves in the browning-cooking level along a path on which both parameters, browning and doneness, more or less increase.

By increasing or decreasing the cooking chamber temperature can be influenced in some way on the course of the path. However, when cooking in a heated oven, tanning and cooking can not be properly separated. If you wait for z. B. always off until the same state of cooking is reached in the core, then at this time the tanning brighter or darker, depending on the set cooking temperature. When the oven temperature is high, the browning is dark. In addition, this will change the cooking times. At high cooking chamber temperature, the cooking time is short, at low cooking temperature, the cooking time is long, if cooked in both cases to the same state of cooking inside.

This also leads to the paradox that to achieve the same state of cooking must be cooked inside long (because of low oven temperature), if the tanning should be weak. On the other hand, if it is to be strongly browned and to have the same inside cooking status, the same food must be cooked only for a short time (because of the high cooking chamber temperature). Thus, with the classical methods, free movement in the browning-cooking state level is not meaningfully possible.

By the separate browning and cooking according to the present invention, it is possible to first brown and aroma in the food 4 bring to. Then z. B. connect a pure cooking, in which the core is still gently brought to the target value. The food 4 has a fine roast aroma in the whole volume. Or it is possible to first approach the cooking state of the core to a large extent and only then to brown it. Then the surface is crisper when removed, if so desired. Combinations of the described methods are also possible.

There are at least the modes of tanning and cooking on the cooking appliance available and selectable. The intensities of tanning and cooking can also be selected, in particular by setting the performance of the participating radio frequency units 13 . 23 , From the operation ago here is the opportunity to operate tanning and cooking so alternately that a certain, desired path through the browning-Garzustand level is passed from the start to the final state, z. B. by user deposited as automatic programs profiles. In particular, operating programs or automatic programs are provided, which for certain food 4 enable defined browning and cooking conditions. For this purpose, the user z. B. via the operating device 11 Store information about the food to be cooked.

In one embodiment, here at least one parameter for the state of preparation of the food is 4 determined. This includes the cooking appliance 1 here a monitoring device 8th , For example, a characteristic quantity for a wave property of the high-frequency radiation sent into the cooking space is compared with a characteristic quantity for a wave property of the high-frequency radiation reflected from the cooking space.

For example, the monitoring device detects 8th at least one scatter parameter. This includes the monitoring device 8th in particular at least one receiving device with at least one antenna. In particular, a receiving device is provided in each case for the first and second frequency ranges. Preferably, at least one antenna is provided for each channel provided in the frequency ranges.

Based on the comparison or the scattering parameter is a parameter for the state of preparation of the food 4 determined. For this purpose, the scattering parameter is detected frequency-dependent, so that a comparison or a scattering parameter can be determined for each frequency range and preferably for each frequency of each frequency range. Thus, based on the scattering parameter in the first frequency range, a parameter for the cooking state of the food can be determined 4 be determined. For example, based on the scattering parameter in second frequency range particularly good a parameter for the browning be determined because the high frequency radiation has a particularly low penetration depth here.

The high frequency generator 3 is set depending on the determined parameter. This is the monitoring device 8th preferably with at least one control device 9 of the high-frequency generator 3 or the cooking appliance 1 operatively connected. The monitoring device 8th includes, for example, at least one microcontroller and at least one memory device. For example, the frequency and / or the power of the high-frequency radiation is set as a function of the parameter. It is also possible to adapt the time and / or the duration of the emission of the radio-frequency radiation as a function of the parameter. The determined parameter can also be displayed, for. B. via the operating device 11 ,

The cooking appliance 1 here comprises at least one thermal heat source 7 , The thermal heat source 7 may be formed, for example, as a conventional radiant heater, z. B. as top heat, bottom heat, Grillheizquelle and / or hot air system. A thermal heat source 7 is for example advantageous if the food to be cooked 4 especially crispy baked or especially strong browned. Moreover, it offers the possibility of being able to select modes known from conventional cooking appliances. The heat source 7 can also be activated depending on the characteristic, z. B. if the characteristic indicates that a desired browning is not achieved in a timely manner.

In the 2 is an example of a course 16 the frequency-dependent penetration depth 6 for usual food 4 shown, for. B. for meat or fish, baked goods, vegetables. It was the penetration depth 6 in centimeters against the frequency in gigahertz. In addition, here are two advantageous frequency ranges 15 . 25 entered. In particular, the frequency ranges extend 15 . 25 only over part of the areas outlined here. For example, the frequency ranges are 15 . 25 in each case one or more ISM bands.

The first frequency range 15 extends here between 0.4 GHz and 2.5 GHz. In this frequency range 15 lies the penetration depth 6 in conventional food 4 for example, 2 cm to just below 1 mm. The frequencies in this frequency range 15 are thus particularly well suited for a deeper heating of the food 4 , so that a volume heating in the food 4 he follows. The absorbed power is distributed over the affected correspondingly large volume of food. The power consumption per cubic centimeter of cooking product volume is therefore comparatively small, which is particularly favorable for heating or cooking, but is not sufficient for browning.

The second frequency range 25 extends here between 5 GHz and about 250 GHz. At frequencies of this frequency range 25 is the penetration depth 6 significantly less than 1 mm and is in particular in the range of a few microns to several 100 microns. Due to the low penetration depth 6 can with the high frequency radiation of the second frequency range 25 a particularly targeted heating of the surface of the food 4 respectively. The of the food 4 absorbed power is thus distributed only to an extremely thin layer on the surface of the food 4 , The affected cooking product volume is thus comparatively very small. The power consumption per cubic centimeter of cooking product volume is therefore very high, which initially leads to drying out of the surface and then to browning. As a result, a targeted browning is possible without it comes to a power input into the interior of the food and thus to a cooking inside.

In addition, the course shows 16 here a very high penetration depth 6 in a frequency range above 10,000 GHz, which is therefore preferably not used.

It has been shown that it is beneficial with the power to cook in the food 4 of usual size is to stay below 400 W and in particular below 200 W. Too much power for cooking leads to übergaren in the edge region of the food 4 because the enlisted energy can not be dissipated inward fast enough. The adaptation of the supplied power is preferably adapted to the cooking weight. For the browning performance it is also advantageous, for comparable reasons, to stay in the power range below 400W and better below 200W. With an efficiency of about 40% are preferably for each frequency range, so for tanning and cooking, in about 1000 W power required. The power consumption of high-frequency units 13 . 23 are preferably chosen so that both processes in a household cooking appliance 1 can run in parallel.

Cooking is particularly gentle when the parameter is derived via the preparation state via a corresponding feedback loop and, for example, based on the determination of the scattering parameter. The feedback loop can, for example, the food 4 and the cooking space 2 and the corresponding connecting elements. Thus, it can be determined on the basis of the scattering parameter or the parameter when the preparation process is finished or when an optimal browning state or state of cooking has been reached.

During operation, scattering parameters are preferably determined on the available antennas and for setting the further power output for each frequency range 15 . 25 or for each channel. For this purpose, the power output is set in particular via a setting of the frequency and / or amplitude and / or phase. The power output can also be determined via the duration and / or the time of transmission of the high-frequency radiation. The scattering parameter contains in particular the feedback of food 4 and cooking space 2 on the in the oven 2 transmitted high-frequency radiation.

To determine the parameter of the preparation state, other sensor means can be used. For example, to determine the state of the cooking, the core temperature of the food 4 be measured with a Gargutthermometer or estimated from the radiated blackbody radiation. The browning state can be determined, for example, with a camera and / or a color sensor. It is also possible that the browning state is determined by a gas sensor which is sensitive to reaction products of browning reactions. The browning condition can also be estimated by means of an infrared camera. It is taken into account that the surface temperature only rises significantly above 100 ° C, if already a drying of the surface and a browning use.

The present invention also offers many advantages over tanning with infrared heating sources in cooking chambers. In the infrared range, z. At 2 microns wavelength, the wavelength is in the order of magnitude of the surface roughness of metals. Because of this structure, the surface becomes a good absorber, regardless of its chemistry and regardless of whether it would be flat as an excellent reflector. For this reason, when cooking with infrared radiation in a stainless steel cooking room, the walls heat up quickly to the cooking chamber temperature, so that a lot of energy is needed to heat the walls.

The embodiment presented here offers two sources which can be switched on and off almost instantaneously 13 . 23 for tanning or cooking. Both sources 13 . 23 are either simultaneously or separately operable, depending on what the food 4 just needs to be supplied: tanning or cooking in the core. In particular, this does not disturb a large heat capacity, such as a hot cooking chamber, which leads to considerable re-cooking in conventional radiators when they are switched off. In addition, the conventional browning a reconnection is often problematic, because the whole amount of space must be heated with.

By the invention tanning and cooking are carried out separately. Thus, a free movement in the browning-cooking state level is possible. If the current state in the plane is known, e.g. B. by the determined characteristic, each target defined at the beginning (browning, state of cooking inside) can be targeted by the two high-frequency units 13 . 23 be controlled accordingly for tanning and cooking.

LIST OF REFERENCE NUMBERS

1

 Cooking appliance

2

 oven

3

 High-frequency generator

4

 be cooked

6

 penetration depth

7

 heating source

8th

 monitoring device

9

 control device

11

 operating device

13

 RF unit

15

 frequency range

16

 course

21

 door

23

 RF unit

25

 frequency range

35

 frequency

Claims (15)

Method for operating a cooking appliance ( 1 ) with at least one cooking space ( 2 ) and at least one high frequency generator ( 3 ), where food ( 4 ) in the cooking chamber ( 2 ) by means of the high frequency generator ( 3 ) is heated by high-frequency radiation, characterized in that high-frequency radiation of at least a first frequency range ( 15 ) and at least a second frequency range ( 25 ) over a defined period in the oven ( 2 ) and that due to a frequency-dependent penetration depth ( 6 ) of the radio-frequency radiation in the first frequency range ( 15 ) the food ( 4 ) is heated substantially continuously by the power of the high-frequency radiation, so that the food ( 4 ) and that due to a frequency-dependent penetration depth ( 6 ) of the High-frequency radiation in the second frequency range ( 25 ) the food ( 4 ) is heated by the power of the high-frequency radiation targeted near the surface, so that a surface texture of the food ( 4 ) is changed characteristically and in particular browned. Method according to the preceding claim, characterized in that the penetration depth ( 6 ) of the radio-frequency radiation in the first frequency range ( 15 ) at least by a factor of 10 and in particular by a factor of 100 higher than the penetration depth ( 6 ) of the radio-frequency radiation in the second frequency range ( 25 ). Method according to one of the preceding claims, characterized in that the penetration depth ( 6 ) of the radio-frequency radiation in the first frequency range ( 15 ) at least one millimeter and in particular at least 10 Millimeters. Method according to one of the preceding claims, characterized in that the penetration depth ( 6 ) of the radio-frequency radiation in the second frequency range ( 25 ) is a maximum of one millimeter and in particular a maximum of 500 microns. Method according to one of the preceding claims, characterized in that a lowest frequency of the second frequency range ( 25 ) is at least twice as large as a highest frequency of the first frequency range ( 15 ). Method according to one of the preceding claims, characterized in that the first frequency range ( 15 ) is between 400 Mhz and 2600 Mhz and / or that the second frequency range ( 25 ) is between 4.5 GHz and 250 GHz. Method according to one of the preceding claims, characterized in that the first frequency range ( 15 ) and / or the second frequency range ( 25 ) lie in at least one ISM band. Method according to one of the preceding claims, characterized in that the high-frequency radiation in the second frequency range ( 25 ) independent of the high frequency radiation in the first frequency range ( 15 ) is generated and / or sent out so that the surface structure of the food ( 4 ) can be changed characteristically regardless of the cooking. Method according to one of the preceding claims, characterized in that the power of the high-frequency radiation in the second frequency range ( 25 ) regardless of the power of the radio frequency radiation in the first frequency range ( 15 ) is set so that an intensity of change of the surface texture of the food ( 4 ) is independent of an intensity of cooking. Method according to one of the preceding claims, characterized in that at least one characteristic variable for a wave property of one of the cooking chamber ( 2 ) reflected high-frequency radiation is detected and with at least one characteristic size for a wave property in the cooking chamber ( 2 ) is compared and that based on the comparison at least one parameter for the state of preparation of the food ( 4 ) is determined. Method according to the preceding claim, characterized in that the comparison of the emitted and the reflected high-frequency radiation takes place in consideration of the frequency and that based on the comparison in the first frequency range ( 15 ) a parameter for the cooking state of the food ( 4 ) and / or that based on the comparison in the second frequency range ( 25 ) a parameter for the browning state of the food ( 4 ) is determined. Method according to one of the two preceding claims, characterized in that the time of transmission and / or the duration of the defined periods and / or the power of the radio-frequency radiation in the first frequency range ( 15 ) and second frequency range ( 25 ) is set depending on the parameter. Method according to one of the preceding claims, characterized in that the food ( 4 ) in addition to the power of the high-frequency radiation with at least one thermal heat source ( 7 ) is heated close to the surface and / or is heated substantially continuously. Cooking appliance ( 1 ) with at least one cooking space ( 2 ) and at least one high frequency generator ( 3 ), where food ( 4 ) in the cooking chamber ( 2 ) by means of the high frequency generator ( 3 ) is heatable by high frequency radiation, characterized in that the high frequency generator ( 3 ) is suitable and designed for radiofrequency radiation of at least a first frequency range ( 15 ) and at least a second frequency range ( 25 ) over a defined period in the oven ( 2 ) and that due to a frequency-dependent penetration depth ( 6 ) of the radio-frequency radiation in the first frequency range ( 15 ) the food ( 4 ) is substantially continuously heated by the power of the high-frequency radiation, so that the food ( 4 ) and that due to a frequency-dependent penetration depth ( 6 ) of the radio-frequency radiation in the second frequency range ( 25 ) the food ( 4 ) can be heated close to the surface by the power of the high-frequency radiation so that a surface structure of the food ( 4 ) is characteristically changeable and in particular browned. Cooking appliance ( 1 ) according to the preceding claim, characterized in that the high-frequency generator ( 3 ) at least two independently operable radio frequency units ( 13 . 23 ) and that with at least one radio frequency unit ( 13 ) the high-frequency radiation of the first frequency range ( 15 ) and at least one other radio frequency unit ( 23 ) the High-frequency radiation of the second frequency range ( 25 ) can be generated and / or emitted.

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