COOKING METHOD FOR OPERATING A COOKING APPLIANCE AND COOKING APPLIANCE

Description

Field of the invention

[0001] The invention relates to a cooking method for preparing food in the cooking chamber of a cooking appliance. The cooking chamber comprises a first opening and a second opening. The second opening can be closed with a closure. Furthermore, the cooking appliance comprises a temperature sensor arranged outside the cooking chamber. The temperature sensor is suitable for detecting the volume of gas escaping from the cooking chamber through the first opening. Furthermore, the invention relates to a cooking appliance for carrying out this cooking method. background

[0002] EP 2 279 682 discloses a cooking appliance with a steam escape sensor that can detect the escape of steam from the food being cooked. The steam escape sensor comprises an opening in the cooking chamber and a temperature sensor located outside the opening. If steam escapes from the food, hot gas escapes through the opening, which can be measured by the temperature sensor. In EP 1 619 443, the temperature sensor is used to open a flap when steam escapes, allowing moisture to be removed from the cooking chamber.

[0003] DE 10 2019 110198 shows a cooking appliance with a sensor located outside the cooking chamber. The sensor can detect a malfunction of a flap located in an air supply duct. Description of the invention

[0004] The object is to provide a cooking process of the type mentioned above, during which measurements of the air humidity prevailing in the cooking chamber can be carried out using a temperature sensor arranged outside the cooking chamber.

[0005] The problem is solved by the subject matter of the independent claim.

[0006] Accordingly, a cooking method serves to prepare food in the cooking chamber of a cooking appliance. The cooking chamber comprises a door, a first opening, a second opening, and a closure for closing the second opening.

[0007] The closure can comprise a flap that can be folded or pushed over the second opening by a stepper or servo motor. The closure can thus be continuously moved from a closed to an open position. A design in which the closure can only assume a closed or an open position is also conceivable.

[0008] The cooking appliance includes a temperature sensor located outside the cooking chamber. This sensor detects the volume of gas escaping from the cooking chamber through the first opening.

[0009] During the cooking process, in a first step, the closure is moved from a first position to a second position in the closing direction in such a way that the movement in the closing direction creates an overpressure in the cooking chamber.

[0010] The movement is a closing movement in the closing direction. This means that in the second position, the second opening is less open than in the first position. The opening cross-section of the second opening decreases due to the closing movement. Preferably, the second opening is completely closed by the closure in the second position.

[0011] After leaving the first position, or especially after reaching the second position, a measurement is taken using the temperature sensor. "After leaving" or "after reaching" refers to a temporal sequence. This means that the measurement can be taken, for example, immediately after leaving the first position or after a predetermined period of time since leaving the first position. For example, measurements can also be taken over a specific period of time since leaving the first position. For example, a measurement could be taken over the five minutes since leaving the first position to determine whether a temperature increase occurs. "After reaching the second position" also means "after leaving the first position."

[0012] The humidity inside the cooking chamber can be determined by measuring the temperature sensor.

[0013] The maximum gradient (dT / dt) of a temperature increase at the temperature sensor is measured.

[0014] The maximum temperature rise rate (dT / dt), determined after the closure is closed, depends on the volume flow through the first opening and the cooking chamber temperature. Furthermore, the volume flow through the first opening depends on the evaporation rate of the food being cooked. This means that the evaporation rate of the food being cooked can be determined by determining the temperature rise rate.

[0015] Measuring the volume flow using the temperature sensor is possible, in particular, due to the temperature sensor's thermal inertia. The more "hot" air flows past the temperature sensor, the faster the temperature sensor adapts to the temperature of the air flow. Therefore, there is a relationship between volume flow and the rate of temperature rise (dT / dt).

[0016] For example, if the temperature sensor detects no temperature increase after closing the lid and the cooking chamber temperature remains constant, the food is not releasing any gas into the cooking chamber. If the lid is opened again after the measurement, it can be assumed that the atmosphere in the cooking chamber is dry as long as the second opening remains open.

[0017] In particular, the measurement is carried out within a certain period of time since leaving the first position, in particular within 10 minutes, in particular within 5 minutes, in particular within 2 minutes, in particular within 1 minute.

[0018] The sequence of process steps, first at least partially closing the closure and then measuring, has the advantage that the measurement can be performed within a controllable cooking chamber climate. This means that by closing the second opening, gas escaping from the food leads to an excess gas volume in the cooking chamber, which is accompanied by overpressure in the cooking chamber. If the second opening is closed, the excess gas volume escapes only through the first opening, so that the gas escaping from the cooking chamber can be measured as precisely as possible at the first temperature sensor.

[0019] In particular, after the measurement has been performed, the shutter can be moved back from the second position to the first position. This is, in particular, an opening movement.

[0020] The sequence of closing, measuring and opening has the advantage that a controlled cooking chamber climate is created for a short time for the measurement, but the cooking process is only influenced as little as possible by the measurement.

[0021] It is advantageous to use the temperature sensor to measure the volume flow through the first opening. This is possible because the temperature inside the cooking chamber is higher than the temperature outside. A temperature increase at the temperature sensor outside the cooking chamber can therefore be attributed to overpressure in the cooking chamber.

[0022] The volume of gas flowing through the first opening allows us to determine the evaporation rate of the food being cooked. This measures the amount of gas released by the food. Gas escapes particularly quickly when the food has exceeded a temperature of 90°C.

[0023] Determining the humidity inside the cooking chamber makes it possible, for example, to display this information to the user. If the humidity inside the cooking chamber is too high or too low, the user can influence the atmosphere in the cooking chamber using familiar measures, such as activating or deactivating a steam generator or changing the position of the lid.

[0024] The measurement taken by the temperature sensor can advantageously be used to control the cooking process. Depending on the measurement, for example, a position of the closure can be determined, and / or the cooking chamber temperature can be set, and / or the cooking process can be ended, and / or the operating power of a device fan can be set, and / or a steam generator can be operated, and / or a new program phase can be initiated.

[0025] The inventive cooking method is advantageously carried out in a dry climate. A dry climate exists, for example, in a convection oven or a microwave with sufficient fresh air supply. In these cooking methods, no steam is introduced into the cooking chamber by means of a steam generator to cook the food in an artificially induced steam atmosphere.

[0026] According to the invention - the invention comprises a cooking appliance with a control system which can carry out one of the described cooking methods. Short description of the drawings

[0027] 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 schematic section through a cooking appliance; Fig. 2 a temperature curve at the temperature sensor; and Fig. 3a correlation between maximum temperature increases and humidity in the cooking chamber at a certain, constant cooking chamber temperature. Way to implement the invention

[0028] The cooking appliance according to Fig. 1 , which is in particular an oven, has a cooking chamber 1 defined by walls 2 and a door 3. The appliance shown as an example can be operated both as an oven and as a steam cooking appliance. It has a conventional resistive heating element with top heat 5a and bottom heat 5b (which, as shown, can be located inside the cooking chamber 1, but can also be located outside the cooking chamber 1). The heating elements 5a, 5b serve to heat the gases in the cooking chamber. Alternatively or in addition to the heating elements 5a, 5b, the appliance can also be equipped with hot air, a grill heating element, or a steam generator.

[0029] A cross-flow fan 5 is arranged outside the cooking chamber 1 as a blower. Depending on the required design, other fan types, such as radial fans, can also be used. The fan conveys air from an intake area 6 into a pressure chamber 7. From the pressure chamber 7, the conveyed air exits into the environment through a front outlet opening 8 of the device. The pressure chamber 7 is delimited at the top by an inclined cover plate 9 and at the bottom by an inclined base plate 10, such that the pressure chamber 7 tapers towards the outlet opening 8. The pressure chamber is closed off at the sides by side walls (not shown). The design of the pressure chamber 7, which tapers towards the outlet opening 8, is not absolutely necessary. A substantially parallel guide of the cover plate 9 and the base plate 10 is also conceivable.

[0030] A first opening 12 and a second opening 16 are arranged in the ceiling of the cooking chamber 1. Opening 16 has a diameter of approximately 2.5 cm, while opening 12 is preferably smaller.

[0031] The device also features a temperature sensor 13, which is located in a protective housing 14. The temperature sensor measures a temperature Tx. The first opening 12 is always open. The protective housing 14 is located in the pressure chamber 7 and communicates with it via a connecting opening 15. The connecting opening 15 is located on the side of the protective housing 14 facing away from the fan.

[0032] A second, closable opening 16 connects the cooking chamber 1 to the intake area 6 in front of the fan 5. A closure 17 is provided to close the second opening 16. This closure consists of a flap 18 that can be pushed more or less far over the mouth of the second opening 16 by a stepper or servo motor 19, such that the closure can be moved essentially continuously from a closed to an open position. A design in which the flap 18 can only assume one closed and one open position is also conceivable.

[0033] To control the closure 17 and the other components of the cooking appliance, a control 20 is provided which, among other things, monitors the temperature signal emitted by the temperature sensor 13.

[0034] Furthermore, a cooking chamber temperature sensor 21 is provided in the cooking chamber 1, with which the temperature of the cooking chamber can be measured. A core temperature sensor (not shown) may also be present, for example in the form of a needle that can be inserted into the food being cooked. However, this core temperature sensor is not necessarily used in the methods described below.

[0035] When the cooking appliance is in operation, the fan 5 is constantly running. However, its power can be adjusted as needed. It draws in air from the environment through openings in the rear wall and side walls of the cooking appliance. This air passes through the intake area 6, is blown into the pressure chamber 7 and leaves it through the outlet opening 8. Since the pressure chamber 7 tapers towards the outlet opening 8, a slight overpressure is created in the pressure chamber 7, i.e. a pressure that is higher than the ambient pressure, while the pressure in the intake area 6 is lower. A certain overpressure must therefore prevail in the cooking chamber 1 for the temperature sensor 13 to detect a temperature increase caused by escaping gas from the cooking chamber. On the other hand, steam can be extracted from the cooking chamber 1 quickly and efficiently by opening the opening 16.

[0036] Furthermore, the task of the fan 5 is to expel the air that has heated up on the outside of the cooking chamber to the outside in order to cool the appliance.

[0037] The appliance shown here can be operated in various modes. For this purpose, the control unit 20 is provided with suitable input elements via which the user can select a desired program. In particular, the appliance can be used conventionally as a cooking appliance, for example, by entering a desired cooking chamber temperature.

[0038] Based on the Fig. 2 The functionality of temperature sensor 13 will now be explained. The starting point is a cooking process in which the food is cooked in the cooking chamber using hot air. This could be, for example, a circulating air mode or a top / bottom heat mode, as is common in conventional ovens.

[0039] During hot air operation, the second opening 16 is always open. The flap 18 does not cover the second opening 16.

[0040] If the temperature of the food rises above 90°C, for example, gas or steam escapes from the food. This gas leaves the cooking chamber 1 through the second opening 16 because the pressure in the intake area 6 is lower than in the pressure chamber 7. Thus, when the flap is open, hardly any or no air or steam flows from the cooking chamber 1 through the first opening 12 to the temperature sensor 13. While the cooking chamber temperature sensor 21 measures the hot air temperature of the cooking chamber of, for example, 210°C, the temperature sensor 13 behind the first opening 12 detects a much lower temperature value of, for example, 40°C because, as mentioned, hardly any or no hot air leaves the cooking chamber 1 through the first opening 12, but air can even enter the cooking chamber 1 through the first opening.

[0041] Therefore, when the flap 18 is open, the temperature sensor 13 is unsuitable for making a statement about the climate in the cooking chamber 1 or about the condition of the food being cooked, for example, the evaporation rate. If a measurement is to be taken using the temperature sensor 13, the flap 18 must first be closed. This means that the flap 18 is moved from a first open position to a second closed position. Now, hot air or steam can essentially only leave the cooking chamber through the first opening 12. The hot air or steam flows past the temperature sensor 13. The temperature sensor 13 detects an increase in temperature.

[0042] Such a course is in Fig. 2 shown in a diagram. The upper diagram shows the temperature curve of the measured temperature Tx. The lower diagram shows the opening position of flap 18.

[0043] In a first scenario, at time t1, flap 18 begins to close. The flap 18 moves from a first position P1 to a second position P2. In this case, flap 18 is fully open in position P1 and fully closed in the second position P2.

[0044] Before closing, i.e., with the flap 18 open, a temperature T1 of approximately 40°C is measured at temperature sensor 13. At this time, the temperature in the cooking chamber is approximately 210°C. Shortly after time t1, in this case at time t2, the temperature sensor 13 detects a temperature increase. The temperature rises to temperature T2 and stabilizes there. T2 corresponds to the maximum cooking chamber temperature of approximately 210°C. At time t4, the flap 18 is opened again, and the temperature drops back to temperature T1.

[0045] A similar, second scenario begins at time t5. The damper 18 is closed, the temperature sensor 13 detects a temperature rise up to temperature T2, the damper 18 is opened again, and the temperature drops back to temperature T1. Compared to the first scenario, beginning at time t1, a steeper temperature rise is detected in the second scenario, beginning at time t5.

[0046] In both scenarios, the controller determines the maximum temperature gradient 30, 31, the absolute temperature difference 40, 41 within a predetermined time period and the time delay 50, 51 between leaving the position P1 of the flap 18 until the temperature increase is detected at times t2 and t6.

[0047] It was determined that the maximum gradient 30, 31 of the measured temperature depends on the volume flow through the first opening 12. The volume flow through the first opening 12 increases the more gas is released from the food into the cooking chamber. This means that the maximum gradient 30, 31 of the measured temperature is a measure of the evaporation rate of the food. In other words, the determined maximum temperature gradient allows conclusions to be drawn about the condition of the food.

[0048] The more gas the food releases into the cooking chamber, the more humid the climate becomes at a given slider position. Thus, the humidity inside the cooking chamber also depends on the determined maximum temperature rise.

[0049] In the first scenario, the maximum temperature gradient 30 is lower than the maximum temperature gradient 31 in the second scenario. This means that in the second scenario, the food emits a higher evaporation rate than in the first scenario. Knowing the temperature prevailing in the cooking chamber and the position of the flap 18, the evaporation rate can be used to determine the air humidity prevailing in the cooking chamber. In this case, a humidity of 26 vol% is determined in the cooking chamber for the first scenario. In the second scenario, due to the greater maximum gradient, a humidity of 42 vol% is determined. These values ​​can be determined using calibration measurements for different cooking chamber temperatures and different flap positions and stored in the cooking appliance.

[0050] The determined time intervals 50 and 51 also represent a measure of the evaporation rate of the food being cooked. The higher the volume flow, the faster the temperature sensor will detect the steam and the shorter the determined time interval will be. The determined time interval 50 of the first scenario is longer than the determined time interval 51 of the second scenario. This indicates that the evaporation rate within the cooking chamber is higher in the second scenario than in the first scenario. With the same cooking chamber temperature and the same slider position, it is also possible to conclude that the air humidity is higher in the second scenario than in the first scenario.

[0051] The advantage of this method is that after determining the time intervals 50 and 51, the measurement is already finished, the slider can be returned to the starting position so that the measuring interval is as short as possible and the cooking process is only slightly influenced by the measuring process.

[0052] Furthermore, the determined absolute temperature differences 40 and 41 can also provide information about the condition of the food being cooked. Temperature differences 40 and 41 are temperature changes determined within a specific time period since leaving position P1. In this case, the time periods are t1 to t3 and t5 to t7. These two time periods are identical and predetermined. Temperature difference 41 is greater than temperature difference 40. This allows us to conclude that the volume flow is greater in the second scenario than in the first scenario.

[0053] The Fig. 3shows a schematic of a series of measurements that examines the relationship between the humidity measured in the cooking chamber in vol% and the maximum temperature rise measured at temperature sensor 13. The steeper the temperature rise at temperature sensor 13, the higher the humidity prevailing in the cooking chamber is at the same cooking chamber temperature and the same slider position P1. This relationship depends on the appliance. It can be verified using a calibration measurement and stored in the control system.

[0054] Now for controlling the cooking process: Information about the humidity inside the cooking chamber or the condition of the food can be used to control the cooking process. These measured values ​​can then be displayed to the user, who could, for example, terminate the cooking process based on the displayed value.

[0055] Depending on the food being cooked, a more or less humid atmosphere is desired in the cooking chamber. If the measured humidity in the cooking chamber is too high, for example, flap 18 can be opened more and / or the appliance fan can be operated at a higher speed. If the measured humidity in the cooking chamber is too low, for example, flap 18 can be closed more and / or the appliance fan can be operated at a lower speed.

[0056] Furthermore, there are certain foods, such as frozen ham croissants, that should be cooked in neither a completely dry nor a completely humid environment. The method according to the invention allows the humidity within the cooking chamber to be determined and the damper and appliance fan to be controlled to ensure the desired humidity level is maintained.

[0057] While preferred embodiments of the invention are described in this application, it is to be clearly understood that the invention is not limited thereto and may be embodied in other ways within the scope of the following claims.

Claims

1. A cooking method for preparing food in the cooking chamber of a cooking device, wherein - the cooking chamber has a door, a first opening, a second opening and a closure for closing the second opening, - the cooking device has a temperature sensor arranged outside the cooking chamber for detecting gas volume flowing out of the cooking chamber through the first opening, characterized in that during the cooking method the closure is moved from a first position to a second position in closing direction such that the movement in closing direction creates an excess pressure inside the cooking chamber, and after leaving the first position, in particular after reaching the second position, a measurement is performed by the temperature sensor, wherein the maximum slope of a temperature change and therefore the air humidity inside the cooking chamber is determined by the temperature sensor under consideration of the cooking chamber temperature.

2. The cooking method according to claim 1, wherein the second opening is completely closed in the second position.

3. The cooking method according to any one of the preceding claims, wherein the volume flow through the first opening is determined by the measurement of the temperature sensor, in particular wherein the volume flow is determined as a function of the cooking chamber temperature.

4. The cooking method according to any one of the preceding claims, wherein the volume flow of gas volumes escaping from the food is determined by the measurement of the temperature sensor.

5. The cooking method according to any one of the preceding claims, wherein in dependence on the measurement by the temperature sensor, - a new target position of the closure is set, and / or - a steam generator is operated.

6. The cooking method according to any one of the preceding claims, wherein in dependence on the measurement by the temperature sensor, process parameters of the cooking method are changed, in particular wherein - the cooking process is ended, and / or - the cooking chamber temperature is adjusted, and / or - the operating power of a device fan is set, and / or - a new program phase is initiated.

7. The cooking method according to any one of the preceding claims, wherein no water vapor is supplied to the cooking chamber from outside the cooking chamber during the cooking method.

8. The cooking method according to any one of the preceding claims, wherein the measurement by the temperature sensor is carried out within a predetermined period of time since leaving the first position, in particular within 10 minutes, in particular within 5 minutes, in particular within 2 minutes, in particular within 1 minute.

9. Cooking device having a control unit adapted for carrying out a cooking method according to any one of the claims 1 to 4, wherein the cooking device has at least the cooking chamber (1), the door (3), the first opening (12), the second opening (16) and the closure (17) for closing the second opening (16), as well as the temperature sensor (13) arranged outside the cooking chamber (1) for detecting gas volume flowing from the cooking chamber (1) through the first opening (12) and cooking chamber temperature sensor (21).