Combination cooking appliance

Description

Field of the invention

[0001] The invention relates to a cooking appliance for cooking food and a method for operating a cooking appliance. background

[0002] Conventional cooking appliances differ in the energy source used for cooking: Microwave ovens generate microwaves to irradiate the food. Conventional ovens use heating elements to heat the cooking chamber. Steam cooking appliances, on the other hand, generate steam in the cooking chamber, to which the food is exposed.

[0003] From the disclosure of document EP 2 322 858 A1, cooking appliances are known which are designed to use all three energy sources simultaneously. Description of the invention

[0004] The object of the invention is to provide a cooking process and a cooking appliance that improve the cooking result.

[0005] The object is achieved by a cooking appliance having the features of patent claim 1 and by a method for operating a cooking appliance according to the features of patent claim 6.

[0006] The cooking appliance has a cooking chamber for accommodating food. Cooking in the context of this invention is intended to encompass all types of heating of food, i.e., warming, heating, but also thawing food, dishes, liquids, etc. The cooking chamber is typically defined by the walls of a hollow body, also called a muffle in the context of ovens, whose open side can be closed with a door. A steam generator is also provided, which allows steam, in particular water vapor, to be supplied to the cooking chamber. This includes external steam generators that generate steam outside the cooking chamber, which steam is then introduced into the cooking chamber via a supply line. However, the claimed steam generator is also intended to encompass internal steam generators, in which the steam is generated within the cooking chamber, for example, by heating water. A container for holding water is preferably connected to the cooking appliance.In addition to the steam generator, a microwave generator is provided for heating the food in the cooking chamber. By providing two different heating methods for the food, this cooking appliance becomes a so-called combination appliance. Furthermore, a hot air generator and / or a heating device are provided. The hot air generator typically comprises a heating element for heating air in the cooking chamber and a fan for distributing / circulating heated air within the cooking chamber. Alternatively or in addition to the hot air generator, a heating device may be provided, for example in the form of a resistance heater, which, depending on its arrangement in / on the cooking chamber in conventional ovens, is also known as "top heat," "bottom heat," or "grill." If the hot air generator and the heating device are provided together, the resistance heater of the heating device is preferably provided in addition to the heating element of the hot air generator.

[0007] Furthermore, a control system is provided, preferably an electronic control system for operating the cooking appliance. The control system activates the steam generator, the microwave generator and the hot air generator or the heating device within a cooking process for cooking the food. It is therefore intended that three different cooking methods, namely steam cooking, microwave cooking and hot air or heating cooking, are used in a common cooking process. The timing of these cooking methods may take place at least partially simultaneously or at different times. The cooking process for cooking a food placed in the cooking chamber is preferably predetermined by a cooking program, which cooking program is executed by the control system and comprises the use of these three cooking methods, which are based on different energy sources and have different influences on the food.

[0008] The control system automatically controls the sequence of cooking modes without user intervention. This includes activating and / or deactivating and / or changing the steam generator, the hot air generator, or the heating device, as well as changing the microwave generator alone.

[0009] In particular, the control system determines the starting point and duration of the respective cooking mode and thus the start and end of the associated generator operation.

[0010] A user of such a cooking appliance may enter the desired cooking program via an input device, for example, one or more selector switches. A cooking program may represent the preparation of a dish. An example cooking program might be "potato gratin." A cooking program may also represent a desired cooking characteristic, such as "energy-efficient" or "gentle," or even a desired food class. Finally, a cooking program may also be defined by a multi-stage selection by the user, for example, as a "gentle" or "fast" cooking program.

[0011] The method for cooking food in a cooking appliance with a cooking chamber for accommodating the food includes the following steps within a cooking process: The introduction of steam into the cooking chamber, the heating of the food in the cooking chamber using microwaves, and the heating of the cooking chamber with a hot air generator or a heating device.

[0012] The list of steps in no way prescribes their order. Depending on the cooking program, the hot air generator may be operated first before the microwave generator and steam generator are switched on. Any temporal combination and sequence of cooking methods should be encompassed by the method. In particular, a cooking process may also be included in which the different cooking methods are carried out one after the other and do not have a common temporal overlap, ie one generator is always switched off first before the next generator is switched on. In another advantageous development, however, all three generators are operated simultaneously, at least for a time.

[0013] Regarding the sequence of the individual steps, reference is made to the above explanations. Such a program element is preferably executed by a controller of the cooking appliance, which controller may have a microprocessor for initiating the steps, as well as a memory for storing the program element. The controller controls the various actuators of the cooking appliance, in particular the steam, microwave, and hot air generators, or the heating device.

[0014] The three cooking methods mentioned above can be activated simultaneously at the start of the cooking process. This results in a very fast cooking process. Alternatively, steam cooking alone can be activated at the start of the cooking process. This achieves gentle cooking while at the same time cooking is relatively fast. Alternatively, microwave cooking alone can be activated at the start of the cooking process. This achieves fast cooking results. In a further development of the invention, during heat / hot air cooking, the temperature in the cooking chamber is regulated in two stages, first to a first target temperature and then to a second, different target temperature which, for example, is higher than the first target temperature. This implements a cooking method that is gentle on the surface of the food being cooked. In another exemplary embodiment, the second target temperature is lower than the first target temperature.

[0015] The cooking appliance and method according to the invention can therefore significantly improve the cooking result, as the food can be cooked as individually as possible by using three different cooking methods during a cooking process. For example, in an exemplary cooking program, the addition of microwaves can be delayed until at least a certain steam level is reached in the cooking chamber, assuming that the steam is primarily regarded as a transfer medium for the microwave to the food. This may result in better energy absorption by the food. Furthermore, the power distribution can be improved and local drying out of the food can be prevented. In another example, convection cooking and steam cooking are defined as the basic cooking methods, and the associated generators are activated at the beginning of the cooking process, which cooking process can in turn be accelerated by the addition of microwaves.The hot air / steam combination, also called "superheated steam," creates a beautiful, even browning, whereas the microwave heats the food from the inside. This way, the food is not only heated from the outside, which saves time. Hot air can also be used to support steam cooking: While the water in the external evaporator is heating up, the cooking chamber can be preheated with hot air. In this mode, too, the microwave can serve as an "accelerator." This allows energy to be immediately introduced into the food, especially at the start of cooking, but also allows heat to be drawn into the interior of the food during continuous heating. For reheating food, the cooking chamber can also be first warmed up with steam and hot air before the microwave is switched on for the actual reheating. The steam ensures that the food does not dry out; the hot air reduces the residual water in the plate.If all three cooking methods are combined, this results in less dried-out food, more firmness, less residual water and time savings.

[0016] The cooking appliance can be operated preferably via a selector switch by selecting a specific cooking program. Such a cooking program preferably carries out the cooking process automatically and automatically adds steam, microwave, and hot air at the desired time. This program-controlled operation relieves the user of unnecessary tasks. During the cooking process, for example, between the start of the cooking process by selecting the program and the end of the cooking process, for example, as a result of the program ending, they no longer have to worry about the dosage, duration, etc. of the respective cooking modes.

[0017] Advantageous developments of the invention are characterized by the subclaims.

[0018] Further developments that are expressly disclosed in connection with the cooking appliance are also to be regarded as being disclosed in connection with the method, and vice versa. Short description of the drawings

[0019] Further embodiments, advantages, and applications of the invention will become apparent from the dependent claims and the following description with reference to the figures. These show: Fig. 1 a cross-section through a cooking appliance according to an embodiment of the invention, Fig. 2 to 4 show flowcharts for process sequences according to embodiments of the invention. Way(s) of carrying out the invention

[0020] The cooking appliance according to Fig. 1comprises a cooking chamber 1, which is delimited by walls 2 and a door 3. The cooking chamber 1 may, for example, have a capacity of 50 liters or more, for example 56 liters. The cooking appliance shown can be operated at least as a steam cooker, a microwave cooker, a convection cooker and / or an oven, as well as a combined steam / microwave cooker, a combined steam / convection cooker, a combined microwave / convection cooker, and a combined steam / microwave / convection cooker. Here and in the following, convection cooking can always alternatively or additionally include conventional heating with bottom and / or top heat and / or grill. "Combined" in this sense encompasses the use of various cooking methods during a cooking process with respect to a food item to be cooked.This can occur simultaneously or at different times; in any case, the corresponding generators are activated within a cooking process for a specific food item, preferably fully automatically, without intervention by the cooking appliance user. If the cooking appliance offers the selection / input of cooking programs, different cooking methods can be used within a selected cooking program that specifies the cooking process. For example, steam cooking can be combined with convection cooking at the beginning of the cooking process, while microwave cooking is activated later in the cooking process.

[0021] The cooking appliance according to Figure 1contains a schematically drawn steam generator 4, which is separate from the cooking chamber 1 and whose steam is supplied to the cooking chamber 1 via a supply line 41. A microwave generator with the reference numeral 11 is schematically arranged in the ceiling and may, for example, deliver a maximum output of 700 watts. The cooking appliance further contains a hot air generator 12 for generating and distributing heated air in the cooking chamber 1. This hot air generator 12 is also only schematically drawn on the rear wall. Alternatively or additionally, the cooking appliance may have the heating devices known from a conventional oven, for example a resistive top heat 5a arranged on the ceiling and a resistive bottom heat 5b arranged on or below the floor, or a grill heater (not shown). Alternatively or additionally, heaters arranged on the sides of the walls may also be provided to heat the cooking chamber 1.

[0022] Outside the cooking chamber 1, a fan 6 is arranged as a blower in a horizontally aligned exhaust air duct 9, which is designed, for example, as a radial fan or a cross-flow fan. At the rear, the exhaust air duct 9 projects beyond the cooking chamber 1 and has an opening on the underside of this projection, to which a hose 7 is connected. The hose 7 opens into an opening 21 of the cooking chamber 1. A schematically drawn sensor 8 for measuring gas escaping from the cooking chamber 1, and in particular steam escaping from the cooking chamber 1, is arranged in the hose 7. In the present case, this sensor 8 is designed as a temperature sensor, for example as an NTC resistor, and is arranged in the lower section of the hose 7 to measure the temperature of the water vapor passing through this point.

[0023] A further opening 20 is optionally arranged in the ceiling of the cooking chamber 1. The further opening 20 has a diameter of approximately 2.5 cm and can be closed or opened by a flap 93. When the flap 93 is open, steam can be extracted from the cooking chamber 1. Furthermore, a temperature sensor 25 is provided in the cooking chamber 1 for recording a temperature in the cooking chamber 1. Furthermore, a core temperature sensor can also be present (not shown), for example in the form of a needle that is inserted into the food to be cooked. Furthermore, a humidity sensor 26 can optionally be provided in the cooking chamber 1, which measures the relative humidity in the cooking chamber 1 and by which steam generation or steam supply by the steam generator 4 is controlled as an alternative or in addition to the gas outlet sensor 8.

[0024] A controller 10 is provided to control the steam generator 4, the microwave generator 11, the hot air generator 12, the top and bottom heat 5a, 5b, the radial fan 6, and other components of the cooking appliance. If a cooking program is set by the user on an input unit, for example in the form of a selector switch, the controller then automatically calls up an associated cooking program in the form of software, which controls the temporal operation of the individual generators. Within the cooking program, which thus defines the cooking process, the steam generator 4 is activated at least once, the microwave generator 11 at least once, and the hot air generator 12 or the heating device 5a, 5b at least once. This mode of operation represents the previously mentioned combined steam cooking / hot air / microwave operation.

[0025] The switching on / activation and / or switching off / deactivation of the individual generators can be triggered by sensor signals, by the operating states of the individual generators, or at fixed times. In this respect, the controller 10 preferably controls the entire cooking process using all three generators 4, 11, and 12 automatically and preferably without user interaction. The program sequence may be fixed or variable depending on the possible influencing factors mentioned above.

[0026] Cooking programs can be tailored either to the type of dish or to the cooking method. The cooking method may include, for example, "quick cooking," "gentle cooking," "energy-efficient cooking," "reheating," or similar.

[0027] Figure 2shows a flowchart for a method according to an advantageous development of the invention. In step S0, a user of the cooking appliance selects a cooking program, preferably using an input or selector switch, which calls up a stored cooking program, the execution of which begins the cooking process. In the present case, this cooking program should include the "regenerating" of food. During regeneration, prepared cold or cooled food is heated for consumption. By selecting the "regenerating" cooking program and, if necessary, in conjunction with pressing a start button, a control system of the cooking appliance automatically begins executing the cooking program in step S1 by starting the microwave generator in step S1 with an initial power of, for example, 500 watts. At the same time, the steam generator and the hot air generator are also started.In step S2 it is checked whether a cooking chamber temperature, for example measured with the temperature sensor 25 from . Figure 1 , has reached a first target temperature of, for example, 130° Celsius. If this is not the case, all three generators remain in operation (for reasons of clarity, all N loops are omitted from the flowchart). Otherwise (Y), in step S3, only the hot air operation is changed so that the cooking chamber temperature remains regulated at the first target temperature. The microwave addition continues unchanged at the first power level; the steam addition by the steam generator also remains unchanged.

[0028] In step S4 it is now checked whether a gas outlet sensor 8 according to Figure 1an assigned threshold is reached. If this is not the case, steam continues to be supplied, microwaves are added, and the cooking chamber temperature is regulated to the first target temperature by the hot air generator. If, however, sufficient steam has been generated so that the gas outlet sensor exceeds its assigned threshold (Y), then in step S5 the steam addition is reduced, as is the microwave addition, whereas the cooking chamber temperature remains regulated unchanged to the first target temperature by the hot air generator. In this case, the reduction in the steam addition occurs depending on the signal from the gas outlet sensor. Here, the steam generator is only operated when, for example, the assigned threshold is undershot by the signal from the gas outlet sensor and is reactivated until the threshold is exceeded again. In this respect, a clocking of the steam addition occurs, the clocking of which is determined by the aforementioned threshold.The reduction in microwave addition depends on the steam addition rate: The greater the steam addition rate, i.e., the longer the interval between steam additions, the more the microwave addition is reduced. The reduction in microwave power may, for example, be proportional to the steam addition rate.

[0029] In step S6, a check is then made to determine whether the cycle pauses are greater than a specified limit, i.e., whether the cycle rate has fallen below a specified level. If this is the case (Y), in step S7, the microwave power is reduced to a second setpoint, in this case, approximately 200 watts, the steam addition is deactivated, and the cooking chamber temperature is regulated by the hot air generator to a second, lower setpoint, for example, 110° Celsius.

[0030] In step S8, the controller terminates the operation of the still active microwave generator and hot air generator, for example, time-controlled or initiated by the user.

[0031] Figure 3 shows a flowchart for a method according to an advantageous development of the invention. In step S10, a user of the cooking appliance selects a cooking program, in this case the "Potato Gratin" cooking program, which is geared towards cooking a specific dish or at least a type of dish. In step S11, a control system of the cooking appliance automatically begins the cooking process by starting the microwave generator at an initial high power of, for example, 700 watts. At the same time, the steam generator and the hot air generator are also started.

[0032] In step S12 it is checked whether the cooking chamber temperature, for example measured with the temperature sensor 25 from Figure 1, has reached a first target temperature of, for example, 200° Celsius. If this is not the case, all three generators continue to operate as they started. Otherwise (Y), in step S13, the measured cooking chamber temperature is regulated to the first predetermined target temperature. The microwave output is reduced to a second power of approximately 400 watts; the steam output by the steam generator remains unchanged.

[0033] In step S14 it is now checked whether the gas outlet sensor 8 according to Figure 1an assigned threshold is reached. If this is not the case, steam continues to be supplied, microwaves are added, and the air in cooking chamber 1 is regulated to the first target temperature by the hot air generator. However, if sufficient steam has been generated so that the gas outlet sensor exceeds its assigned threshold (Y), a slide is operated in step S15, which opens an opening in the cooking chamber so that steam can escape from the cooking chamber through this opening. Otherwise, the steam addition by the steam generator is switched off, and the microwave addition is reduced to a second power of approximately 100 W.

[0034] In step S16, a check is then performed to determine whether a period of time x has already passed since the threshold was exceeded by the gas outlet sensor signal, where x is, for example, 12 minutes. If this is the case (Y), the microwave generator is shut down in step S17. The steam supply remains shut down, and the hot air generator regulates to a second target temperature of 210° Celsius. In step S18, the control system then terminates operation of the still-active hot air generator.

[0035] Figure 4shows a flowchart for a method according to a further advantageous development of the invention. In step S20, a user of the cooking appliance again selects a cooking program, in this case the "Power Steam" cooking program for gentle cooking of the food. By selecting the "Power Steam" program, a control system of the cooking appliance automatically begins the cooking process in step S21 by starting the microwave generator with an initial power of, for example, 400 watts, and simultaneously starting the steam generator and the hot air generator. In step S22, a check is made as to whether the cooking chamber temperature, for example measured with the temperature sensor 25 from Figure 1, has reached a first target temperature of, for example, 100° Celsius. If this is not the case, all three generators remain in operation. Otherwise (Y), in step S23 only the hot air operation is changed so that the hot air generator is now operated at a reduced level. In particular, in this and other exemplary embodiments, reduced hot air operation can be understood to mean interval operation. By no longer adding hot air continuously but at intervals, the supplied hot air energy is reduced. In particular, as in the present exemplary embodiment, the duration of an addition of hot air can depend, for example, on the duration of the addition of steam. In particular, a ratio between the addition of steam and the addition of hot air can be predetermined for the reduced operation. This ratio can relate to the duration of the addition of hot air and steam or to their energy ratio.The microwave addition remains unchanged at the first power level of 400 watts; the steam addition from the steam generator also remains unchanged.

[0036] In step S24 it is now checked whether the gas outlet sensor 8 according to Figure 1 has reached an assigned threshold. If this is not the case, steam continues to be supplied, microwaves are added, and the hot air generator is operated as described in step S23. However, if sufficient steam has been generated so that the gas outlet sensor exceeds the assigned threshold (Y), the steam addition is reduced in step S25 by operating the steam generator in a timed manner depending on the signal from the gas outlet sensor. The microwave addition remains unchanged. The hot air generator is also operated unchanged.

[0037] In step S26, a check is then made to determine whether the cycle pauses between steam additions are greater than a predefined limit, i.e., whether the cycle rate has fallen below a predefined level. If this is the case (Yes), in step S27, the microwave addition is reduced the longer the cycle pauses are, and preferably proportionally to the cycle pauses. The hot air generator and steam generator remain in the mode defined in step S23. In step S28, the customer then terminates the operation of the still active generators at a time of their choosing.

Claims

1. Cooking appliance for cooking food, comprising a cooking chamber (1) for holding the food to be cooked, a steam generator (4) for supplying steam to the cooking chamber (1), a microwave generator (11) for heating the food to be cooked, a hot air generator (12) and / or a heating device (5a, 5b) for heating the cooking chamber (1), a control (10) for automatically activating the steam generator (4), the microwave generator (11) and the hot air generator (12) or the heating device (5a, 5b) within a common cooking process for cooking the food, characterised in that the controller (10) is adapted to automatically change the power of the microwave generator (11) as a function of a sensor signal from a gas outlet sensor (8) for detecting gas escaping from the cooking chamber (1), the term "change" not including activation or deactivation of the microwave generator.

2. Cooking appliance according to one of the preceding claims, with an input device for entering a cooking programme, in which the controller (10) is adapted to automatically activate the steam generator (4), the microwave generator (11) and the hot air generator (12) or the heating device (5a, 5b) as a function of the cooking programme entered.

3. Cooking appliance according to claim 2, in which the control unit (10) is adapted to automatically deactivate the steam generator (4), the microwave generator (11) and the hot-air generator (12) or the heating device (5a, 5b) as a function of the cooking programme entered.

4. Cooking appliance according to one of the preceding claims, in which the heating device (5a, 5b) contains - a top heating device (5a), and / or - a bottom heating device (5b), and / or - a grilling device.

5. Cooking appliance according to one of the preceding claims, with a flap (93) for closing an opening (20) in the cooking chamber (1), in which the control unit (10) is adapted to automatically move the flap (93) to open and / or close the opening (20) during the cooking process.

6. Method for cooking food in a cooking appliance with a cooking chamber for receiving the food according to one of the preceding claims, comprising the following steps within a common cooking process: (a) supplying steam to the cooking chamber (1) by means of a steam generator, b) heating the food in the cooking chamber (1) by means of microwaves of a microwave generator, c) heating the cooking chamber (1) with a hot air generator (12) and / or a heating device (5a, 5b), characterised in that a controller (10) is adapted to automatically change the power of the microwave generator (11) as a function of a sensor signal from a gas outlet sensor (8) for detecting gas escaping from the cooking chamber (1), wherein the term "change" does not include activation or deactivation of the microwave generator.

7. Method according to claim 6, in which a simultaneous or mutually time-delayed sequence of steps a) to c) within the cooking process is automatically initiated as a function of a selected cooking programme.

8. Method according to claim 6 or claim 7, in which steps a) to c) are initiated simultaneously at the beginning of the cooking process.

9. Method according to claim 6 or claim 7, in which only step a) is initiated at the beginning of the cooking process.

10. Method according to claim 6 or 7, in which step b) alone is initiated at the beginning of the cooking process.

11. Method according to any one of claims 7 to 8, in which, in step c), the cooking chamber (1) is heated to a first target temperature in a first phase, and in which, in step c), the cooking chamber (1) is heated in a second phase to a second setpoint temperature which differs from the first setpoint temperature.

12. Method according to one of the preceding claims 6 to 11, in which a control unit (10) automatically starts and ends steps a) to c) as a function of an entered cooking programme, and in which the start and termination of each of the steps a) to c) is triggered by one or more of the following events - a start of the cooking process by entering a cooking programme, - a signal from a gas outlet sensor (8) for detecting gas escaping from the cooking chamber (1), - a signal from a temperature sensor (25) for detecting a temperature in the cooking chamber (1), - a signal from a core temperature sensor for introduction into the food to be cooked, - an operating parameter of a steam generator (4) for supplying steam to the cooking chamber (1), - an operating parameter of a microwave generator (11) for generating the microwaves, - an operating parameter of the hot air generator (12) or the heating device (5a, 5b), - a timing of a steam addition by the steam generator (4), - the reaching of a predetermined point in time, - the expiry of a time interval.