WO2025082710A1 - Cooking appliance comprising a cooking chamber and method for operating a cooking appliance - Google Patents

Abstract

The invention relates to a cooking appliance (2) having a housing (4), a cooking chamber (6) arranged in the housing (4), a controller (8) and a first heater (10, 12, 14) connected for signal transmission to the controller (8) for heating a cooking item located in the cooking chamber (6), characterised in that the cooking appliance (2) has, in addition to the first heater (10, 12, 14), a second heater connected for signal transmission to the controller (8), wherein the second heater is designed as a push-in part (20) of the cooking appliance which can be pushed into the cooking chamber (6) in the manner of a cooking item carrier and, in a pushed-in state, can be energised by means of the housing (4), and wherein the energised push-in part (20) itself can be heated merely by means of its electrical resistance. The invention also relates to a method for operating a cooking appliance (2).

Description

Description

Cooking appliance with a cooking chamber and method for operating a cooking appliance

The invention relates to a cooking appliance according to the preamble of patent claim 1 and a method for operating such a cooking appliance.

Such cooking appliances and methods are already known in the prior art in a variety of embodiments. The known cooking appliances comprise a housing, a cooking chamber arranged in the housing, a controller, and a first heater connected to the controller for signal transmission for heating a food item located in the cooking chamber.

The invention therefore addresses the problem of improving a cooking appliance with a cooking chamber and a method for operating a cooking appliance.

According to the invention, this problem is solved by a cooking appliance having the features of patent claim 1, which is characterized in that, in addition to the first heating element, the cooking appliance has a second heating element connected to the control system in a signal-transmitting manner. The second heating element is designed as an insertable part of the cooking appliance that can be inserted into the cooking chamber in the manner of a food carrier and, in an inserted state, can be supplied with current via the housing, and the powered insertable part itself can be heated solely by means of its electrical resistance. It is therefore proposed to heat an insertable part, for example a baking tray or baking rack, directly, i.e. without the use of an additional heating coil or an additional heating element that would be more or less integrated into the insertable part. By directly heating the insertable part, both weight and volume are saved, as well as additional electrical connections. The active heating of the insertable part takes place by means of directly supplied electrical energy, so that the heating of the insertable part essentially takes place via its respective individual, inherent ohmic resistance. A suitable design of the insert part, particularly with regard to the design of the electrical resistance, is advantageous. Particular attention is drawn here to the geometry, sheet thickness, alloy, and power feed contacts, by means of which the distribution of heating of the insert part and the energy input into the insert part can be optimized. For example, an electrical connection of the insert part is possible by means of the two cooking chamber side walls formed by the housing, and ideally at least one further electrical connection of the insert part is possible by means of the cooking chamber rear wall formed by the housing. Furthermore, the problem according to the invention is solved by a Method with the features of patent claim 8. Advantageous embodiments and further developments of the invention emerge from the following subclaims.

According to the invention, the energized insert part consists of a single, monolithic metal layer and a dirt-repellent protective coating, in particular on both sides.

The advantage achievable with the invention lies, in particular, in the improvement of a cooking appliance with a cooking chamber and a method for operating a cooking appliance. Due to the inventive design of the cooking appliance and the method, a substantially uniform heating of a food item arranged in the cooking chamber of the cooking appliance according to the invention is possible without the cooking chamber having to be preheated beforehand. Accordingly, the invention enables a very efficient and thus energy-saving heating of the food item during a cooking process taking place in the cooking chamber.

In principle, the cooking appliance according to the invention can be freely selected within wide, suitable limits in terms of type, mode of operation, material, and dimensions. For example, the cooking appliance according to the invention can be designed as an oven with a first heating element configured as an electrical resistance heater, with a first heating element comprising a steam generator, with a first heating element comprising a microwave generator, or as a combination appliance with a first heating element configured as a plurality of different heating elements. Furthermore, it is conceivable for the cooking appliance according to the invention to be designed as a household appliance or as a commercial appliance, i.e., a cooking appliance for professional use.

An advantageous development of the cooking appliance according to the invention provides that the insert part is designed as a dividing element for dividing the cooking chamber into a first partial cooking chamber and a second partial cooking chamber. In this way, the insert part is simultaneously designed to be suitable for subdividing the cooking chamber into two smaller partial cooking chambers, so that, on the one hand, heating only a partial volume corresponding to one of the two partial cooking chambers is required, instead of a total volume corresponding to the entire cooking chamber. On the other hand, no additional component of the cooking appliance according to the invention is required for this purpose.

Alternatively or additionally, a particularly advantageous development of the cooking appliance according to the invention provides that the insert part is designed as a food support for a food, preferably as a baking tray or a grill. As a result, the insert part, alternatively or in addition to its use as a separating element, can simultaneously be used as a food support, in particular as a baking tray or a grill, so that a corresponding food carrier can be saved in the cooking appliance according to the invention according to the present development.

In the prior art, the food surfaces in the cooking chamber directly exposed to the hot air are usually overheated and dry out, while the interior of the food, and especially the food surfaces resting on a baking tray, are heated only insufficiently and indirectly due to a lack of convection. This imbalance is particularly noticeable, for example, with food such as pizza or the like. In addition, the required preheating of the entire cooking chamber in the prior art usually results in a lot of energy being lost because the hot air must first heat the baking tray and only then does the thermal energy penetrate through the baking tray into the base of the food. In principle, therefore, large (housing) masses are heated by the heated air, with only a small proportion actually being needed for the food and actually benefiting it. The invention, in particular according to the aforementioned development, provides a remedy here. The invention solves the problem, namely on the one hand an efficient introduction of the (thermal) energy into the food and on the other hand a (sensory) optimized ratio of the free food surface to the food surface lying on the baking tray and to the food core.

A further advantageous development of the cooking appliance according to the invention provides that the control system and the insert are designed such that the power supply to the insert can be controlled or regulated by means of the control system, preferably as a function of a cooking process for cooking the food, particularly preferably as a function of an automatic program stored in the control system for carrying out the cooking process. In this way, the respective electrical voltage or electrical current for powering the insert can be determined as a ratio to the indirect determination of the respective prevailing temperature of the insert, so that the process of energy release into the insert can be actively controlled or regulated, depending on the desired cooking program.

Another advantageous development of the cooking appliance according to the invention provides that the power supply to the insert part is carried out by means of insert guides of the housing for guiding and holding the insert part relative to the housing, preferably that the insert part and the housing are designed such that the power supply to the insert part is carried out by means of more than two electrical feed contacts. The feed contacts, i.e. feed points, for the insert part are therefore to be introduced into the housing. This enables the electrical connection of the insert part to a power source of the cooking appliance according to the invention in a particularly simple manner in terms of design and production technology. By using several feed points, By observing Kirchhoff's laws, the local current density and thus the lateral locality of the energy input into the plug-in part can be significantly and sufficiently influenced. In addition to the plug-in guides molded into one side of the housing, plug-in grids or plug-in rails arranged detachably or permanently on one side of the housing are also conceivable as plug-in guides.

A further advantageous development of the cooking appliance according to the invention provides that the cooking appliance is suitably designed for a plurality of plug-in parts that can be supplied with current in the aforementioned manner, wherein the plurality of plug-in parts can be operated in parallel. In this way, a plurality of simultaneous cooking processes for preparing one type of food each are possible in the cooking chamber of the cooking appliance according to the invention.

Furthermore, another advantageous development of the cooking appliance according to the invention provides that the insert part is designed to be suitable for power supply via only two electrical feed contacts by means of a predetermined ohmic resistance of the insert part, preferably by means of a predetermined thickness and/or by means of certain alloy components and/or by means of a geometric configuration of the insert part. The insert part can therefore be designed with an increased and/or defined, for example lateral, ohmic resistance, for example by means of a thinner insert part, alloy components or mechanical impressions and/or notches and/or patterns and/or interruptions or the like in the insert part, in order to ensure a simplified energy input that may be sufficient with only two electrical contacts. This option can further reduce the effort involved in configuring the cooking appliance according to the invention.

In accordance with the multitude of conceivable embodiments of the cooking appliance according to the invention, the method according to the invention can also be freely selected within wide suitable limits.

An advantageous development of the method according to the invention provides that the power supply to the plug-in part is carried out by means of a clocked switching power supply, wherein the variation of the clock frequency corresponds to an effective output voltage of a power supply of the plug-in part to be regulated, preferably that the power supply is carried out by means of a clocked output current of the power supply in a range of 50 kHz to 1 MHz. This makes it possible to utilize the so-called skin effect. The current displacement inside the plug-in part results in an increased current density and thus heating of the surface of the plug-in part. The induced resistance ZB increases, the voltage can be selected higher and the current can be lower, which leads to smaller contact designs and thinner connecting lines. The required, relatively Low voltages and high currents can thus be provided cost-effectively, while also being easily monitored and adjusted within the control system. The typically necessary and complex smoothing of the output current in switch-mode power supplies can be advantageously dispensed with, since no pure DC component is required for heating, provided no special acoustic requirements are imposed. At higher frequencies, hollow conductors can be used to supply energy to the contact surfaces.

A further advantageous development of the method according to the invention provides that at the beginning of a heating phase during the cooking process, an impedance measurement is carried out on the insert part, preferably that an effective value of a primary input voltage of a transformer is varied by means of a triac, IGBT, or FET. In this way, the optimal output frequency for the specific insert part can be determined, for example, with different thicknesses and/or geometric designs of the insert parts in a plurality of insert parts. In this context, it is further advantageous to be able to vary the effective value of the input voltage of the transformer by means of a triac/IGBT/FET, i.e. a controlled, soft intermediate circuit, in order to be able to optimize and adapt the output voltage independently of the output frequency - adapted to the impedance. With the present development, parallel operation of more than one insert part on parallel electrical contacts is also largely possible.

One aspect is that at the beginning of the heating phase during the cooking process, an impedance measurement is performed on the insert. The determined impedance is assigned to a specific program sequence, particularly without further user intervention, and the program sequence is started automatically. This makes it possible to transmit a cooking process specification to the appliance using specific inserts.

With the aforementioned options, active heating of existing, commercially available baking trays or wire racks with sufficient electrical conductivity is also possible, provided the impedances are within a specified range and the voltage can be sufficiently adapted. Accordingly, the continued use of conventional trays and racks is possible. All that is required is sufficient electrical contact.

Using the impedance measurement described above, it is possible to distinguish between the insert parts specifically optimized and manufactured for the invention, such as sheets and grids, and the aforementioned commercially available insert parts, such as existing sheets or grids. This distinction would make it possible to For example, the operation of baking trays or the like that are not part of the appliance, i.e. insert parts that do not correspond to the cooking appliance according to the invention, can be excluded from the method according to the invention, namely the function of a heatable baking tray or the like.

The impressed impedance for the specific insert, for example the baking tray, can also be used to detect and identify various inserts, such as the aforementioned baking tray, racks, or the like. A simple, individual identification and assignment of specific inserts, such as baking trays or racks, would therefore be obvious, starting an automatic, predetermined food preparation process. This could, for example, allow standard functions to be assigned to a baking tray, such as a specific baking tray always being used for baking rolls, meaning that the corresponding baking program can be automatically triggered after this tray is inserted. The cooking program that is to be automatically started with the respectively detected insert, for example the baking tray, could, for example, be configured to be configurable by the end customer. The corresponding action, i.e., the corresponding automatic program, could be started simply by inserting the insert, designed, for example, as a baking tray, and closing the cooking chamber door without any further operator action on the cooking appliance, in particular automatically, for example, after a period of 5 seconds.

An embodiment of the invention is shown purely schematically in the drawing and is described in more detail below. It shows the single figure

Figure 1 shows an embodiment of the cooking appliance according to the invention for carrying out the method according to the invention in a sectional side view.

In the only Fig. 1, an embodiment of the cooking appliance according to the invention for carrying out the method according to the invention is shown purely by way of example.

The cooking appliance 2, designed as a household oven, comprises a housing 4, a cooking chamber 6 arranged in the housing 4, a control unit 8, and a total of three first heaters 10, 12, 14, which are connected to the control unit 8 for signal transmission, for heating a cooking item (not shown) located in the cooking chamber 6. The heater 10 is designed as a top heat element, the heater 12 as a bottom heat element, and the heater 14 as a circulating air heater interacting with a fan (not shown) of the cooking appliance 2. The first heaters 10, 12, 14 are designed as usual. Furthermore, the cooking appliance 2 comprises a A cooking chamber door 16 which closes in a manner known per se to those skilled in the art, and an operating unit 18 which is connected to the control unit 8 in a signal-transmitting manner for inputting user commands from an end user (not shown) of the cooking appliance 2.

According to the invention, the cooking appliance 2 has, in addition to the first heaters 10, 12, 14, a second heater which is connected to the controller 8 in a signal-transmitting manner, wherein the second heater is designed as an insert part 20 of the cooking appliance 2 which can be inserted into the cooking chamber 6 in the manner of a food carrier and which can be energized by means of the housing 4 in an inserted state shown in Fig. 1, and wherein the energized insert part 20 itself can be heated only by means of its electrical resistance.

The insert part according to the invention can, for example, be designed as a dividing element for dividing the cooking chamber into a first partial cooking chamber and a second partial cooking chamber. In the present embodiment, however, the insert part 20 is designed as a food support for the food to be cooked, namely as a baking tray.

Furthermore, the controller 8 and the insert part 20 are designed such that the power supply to the insert part 20 can be controlled or regulated by the controller 8 depending on a cooking process for cooking the food, namely depending on an automatic program stored in the controller 8 for carrying out the cooking process. The power supply to the insert part 20 is also carried out by means of insert guides (not shown) formed in the housing 4 for guiding and holding the insert part 20 relative to the housing 4. Alternatively or additionally, the power supply to the insert part 20 can also be carried out by means of insert grids (not shown) arranged on the sides of the housing 4 or by means of insert rails (likewise not shown) arranged on the sides of the housing 4. The insert part 20 and the insert guides of the housing 4, i.e. the housing sides of the housing 4 and/or the insert grids of the housing 4 and/or the insert rails of the housing 4, are designed such that the insert part 20 is supplied with current by means of at least two electrical feed contacts. Irrespective of this, the insert part 20 in the present exemplary embodiment is designed for current supply by means of only two electrical feed contacts by means of a predetermined ohmic resistance of the insert part 20, preferably by means of a predetermined thickness and/or by means of certain alloy components and/or by means of a geometric configuration of the insert part 20. The aforementioned insert rails are, for example, telescopic and serve for manual and/or automatic movement of the insert part 20 into or out of the cooking chamber 6.

The cooking appliance 2 is designed here for a plurality of

Insert parts 20 are suitably designed, wherein the plurality of insert parts 20 can be operated in parallel. Only one of the insert parts 20, namely the baking tray mentioned above, is shown in Fig. 1.

In the following, the functioning of the cooking appliance according to the invention and the method according to the invention according to the present embodiment are explained in more detail with reference to Fig. 1.

By means of the cooking appliance 2 explained above, the food to be cooked in the cooking chamber 6 is heated, on the one hand, by the first heaters 10, 12, 14 and, on the other hand, by the second heater, namely the insert part 20. The second heater, designed as a powered insert part 20, is heated solely by its electrical resistance. The insert part 20 is powered by a clocked, not-shown switching power supply, wherein the variation of the clock frequency corresponds to an effective output voltage of a power supply of the insert part 20 to be regulated, namely such that the power is supplied by means of a clocked output current of the power supply in a range from 50 kHz to 1 MHz. Furthermore, at the beginning of a heating phase during a cooking process for cooking the food in the cooking chamber 6, an impedance measurement is performed on the insert part 20, wherein an effective value of an input voltage of a transformer is varied by means of a triac, IGBT, or FET. See also the relevant statements in the introduction to the description, which are hereby fully part of the present explanation of the method according to the invention in accordance with the present exemplary embodiment.

Furthermore, the following comments should be noted:

Both the heating and the intelligent evaluation and identification of the baking tray, i.e., the insert part 20, should initially be implemented using i*i*Z, where i=current supplied to the insert part 20 and Z=apparent resistance, impedance. For generally low-impedance baking trays, lateral power supply is suitable using sliding or clamp contacts on the sides of the housing 4 facing the cooking chamber 6 and, in a preferred embodiment, additionally on the rear of the housing 4 facing the cooking chamber 6. The same applies to insert guides of the housing 4 designed as insert grids or insert rails.

Due to the low ohmic resistance in the order of 1 to about 5 ohms, an effective voltage value of 25 to about 53 V at a current of 24 to 11 A is required for an approximate energy consumption of, for example, 600 W.

By a more precisely defined, significant increase in the fundamental frequency, without harmonic content, in the range from 50 kHz to 1 MHz, the skin effect occurring in conductors with a large cross-section, such as thick sheets and grids of baking trays, can be and cooking grates, cause a significant increase in the resistive component due to current displacement, resulting in higher voltage but significantly lower currents. The higher voltages, for example, 100 V to 300 V, would also benefit the electrical contacts and reduce heat losses in the supply lines to the electrical contacts.

It is advantageous to use adjustable switching power supplies with variable input voltage without additional smoothing. Since the cooking chamber 4 of the cooking appliance 2, except for the cooking chamber door 16, represents an excellent Faraday cage, EMC problems essentially do not arise. Furthermore, it is advantageous to vary the electrical contacts, i.e., feed points, and thus the lateral current supply of the insert part 20, designed as a baking tray, with respect to the feed points, thus enabling an ideal current flow and advantageous energy distribution. Furthermore, within the meaning of this embodiment, it is advantageous if a "cold measurement" of the impedance is also performed before the start of the cooking process in order to locate the position of the food on the baking tray, namely the insert part 20, either from the amplitude/frequency response or - even more simply - at omega=0 by appropriately switching the feed contacts. Then, by appropriately selecting the feed contacts, ideally only heat this exact area or otherwise benefit from the positioning of the food. It is also theoretically conceivable within the meaning of this embodiment to detect and meaningfully evaluate the gradient of the increase in the local impedance. From this gradient, for example, an estimate of the mass to be cooked, i.e., heated, as well as the local temperature can be determined.

Due to the inventive design of the cooking appliance 2 and the method, a substantially uniform heating of the food to be cooked arranged in the cooking chamber 6 of the cooking appliance 2 is possible without the cooking chamber 6 having to be preheated beforehand. Accordingly, the invention according to the present embodiment enables a very efficient and thus energy-saving heating of the food to be cooked during the cooking process taking place in the cooking chamber 6.

However, the invention is not limited to the present embodiment. See the relevant statements in the introduction to the description as well as the alternative and optional embodiments mentioned in the explanation of the specific embodiment.

Claims

Patent claims 1 . Cooking appliance (2) with a housing (4), a cooking chamber (6) arranged in the housing (4), a controller (8), and a first heater (10, 12, 14) connected to the controller (8) for transmitting signals for heating a food to be cooked in the cooking chamber (6), characterized in that the cooking appliance (2) has, in addition to the first heater (10, 12, 14), a second heater connected to the controller (8) for transmitting signals, wherein the second heater is designed as an insert part (20) of the cooking appliance (2) that can be inserted into the cooking chamber (6) in the manner of a food carrier and, in an inserted state, can be supplied with current by means of the housing (4), and wherein the energized insert part (20) itself can be heated only by means of its electrical resistance, and wherein the energized insert part (20) consists of a single, monolithic metal layer and a dirt-repellent protective coating, in particular on both sides. 2. Cooking appliance according to claim 1, characterized in that the insert part is designed as a separating element for dividing the cooking chamber into a first partial cooking chamber and a second partial cooking chamber. 3. Cooking appliance (2) according to claim 1 or 2, characterized in that the insert part (20) is designed as a food support for a food to be cooked, preferably as a baking tray or a grill rack. 4. Cooking appliance (2) according to one of claims 1 to 3, characterized in that the control (8) and the insertion part (20) are designed in such a way that the current supply to the insertion part (20) by means of the control (8), preferably in dependence on a cooking process for cooking the food, particularly preferably in dependence on a Control (8) stored automatic program for carrying out the cooking process, can be controlled or regulated. 5. Cooking appliance (2) according to one of claims 1 to 4, characterized in that the power supply to the insert part (20) takes place by means of insert guides of the housing (4) for guiding and holding the insert part (20) relative to the housing (4), preferably that the insert part (20) and the housing (4) are designed such that the power supply to the insert part (20) takes place by means of more than two electrical feed contacts. 6. Cooking appliance (2) according to one of claims 1 to 5, characterized in that the cooking appliance (2) is designed to be suitable for a plurality of plug-in parts (20) which can be supplied with current in the aforementioned manner, wherein the plurality of plug-in parts (20) can be operated in parallel to one another. 7. Cooking appliance (2) according to one of claims 1 to 6, characterized in that the insert part (20) is designed to be suitable for energization by means of only two electrical feed contacts by means of a predetermined ohmic resistance of the insert part (20), preferably by means of a predetermined thickness and/or by means of certain alloy components and/or by means of a geometric configuration of the insert part (20). 8. Method for operating a cooking appliance (2) according to one of claims 1 to 7, according to which the food to be cooked in the cooking chamber (6) is heated on the one hand by means of the first heater (10, 12, 14) and on the other hand by means of the second heater, wherein the second heater designed as an energized insert part (20) is heated only by means of its electrical resistance. 9. The method according to claim 8, characterized in that the power supply to the plug-in part (20) is effected by means of a clocked switching power supply, wherein the variation of the clock frequency corresponds to an effective output voltage of a power supply of the plug-in part (20) to be regulated, preferably that the power supply is effected by means of a clocked output current of the power supply in a range of 50 kHz to 1 MHz. 10. The method according to claim 8 or 9, characterized in that at the beginning of a heating phase during the cooking process, an impedance measurement is carried out on the insert part (20), preferably that an effective value of an input voltage of a transformer is varied by means of a triac or IGBT or FET. 11. The method according to claim 10, characterized in that at the beginning of a heating phase during the cooking process, an impedance measurement is carried out on the insert part (20) and the impedance determined in this way is assigned to a specific program sequence, in particular without further intervention by the user, and the program sequence is started automatically.