Domestic steam cooking appliance and method for operating same

Abstract

The invention relates to a domestic steam cooking appliance (1) comprising an evaporator (6) which can be filled with water (W) and which does not have a level sensor, a water source (7) for supplying the evaporator (6) with water, a controllable conveying device (8) for conducting water (W) from the water source (7) into the evaporator (6), and a control device (10) for controlling the conveying device (8) in such a way that defined amounts of water (W) can be conducted from the water source (7) into the evaporator (6), wherein the domestic steam cooking appliance (1), in particular the control device (10), is designed to not fill the evaporator (6) with water in an end phase (P3) of a steam cooking process (P1-P3) which begins upon reaching a set cooking duration minus a defined period of time for use of residual water. The invention also relates to a method for operating a domestic steam cooking appliance (1).

Description

[0001] 202401406

[0002] 1 / 25

[0003] Household steam cooking appliance and method for operating it

[0004] The invention relates to a household steam cooker comprising a water-fillable, level-insensitive evaporator, a water source for supplying the evaporator, a controllable conveying device for directing water from the water source to the evaporator, and a control device for controlling the conveying device such that defined quantities of water can be directed from the water source to the evaporator. The invention also relates to a method for operating such a household steam cooker.

[0005] DE 10 2008 056 324 A discloses a method for refilling a steam generator with water to a specific fill level by controlling a heating device of the steam generator and a water refilling device of the steam generator at least as a function of output data from a level measuring device, as well as providing a first quantity characteristic for a substantially constant quantity M of water to be refilled per refilling interval, as well as providing a second quantity characteristic for a number Z of refilling intervals between two successive measuring intervals, and a steam generator and a cooking device.

[0006] DE 10 2014 206 281 A1 discloses a method for operating an evaporator of a household appliance equipped with a heater, wherein the evaporator has at least part of a level detector for detecting a predetermined level and at least part of an overheat detector for detecting overheating of the heater, wherein the method comprises at least the following steps: filling the evaporator at least to the predetermined level; emptying the evaporator by means of an emptying device; starting a time measurement when 202401406

[0007] 2 / 25 If the predetermined fill level is undershot, the evaporator heater is switched on; the timer is stopped if overheating of the heater is detected; a delivery rate is calculated for emptying the evaporator based on the emptying time determined by the timer. A steam treatment device is set up to carry out the process.

[0008] EP 2 860 458 A1 relates to a method for operating a cooking appliance in the form of a combi steamer, which comprises a cooking chamber, a heating element, at least one fan for circulating the atmosphere in the cooking chamber, at least one temperature sensor, a control device, and a device for introducing water of an adjustable volume flow, which is directed onto the fan and converted into steam by means of fine dispersion. It is characterized in that, at the beginning of the cooking process in the "cooking / steaming" mode, a predetermined volume flow of water, dependent on the specific appliance type, is introduced into the cooking chamber onto the fan wheel, and that, depending on the cooking chamber temperature detected by the temperature sensor, the control device determines a time period after which the volume flow of water is reduced. A cooking appliance for carrying out the method is also disclosed.

[0009] EP 3 840 528 A1 discloses a steam generator comprising: a water tank, an upper heating element and a lower heating element, a first temperature sensing device covering a temperature sensing range that includes the area covered by the two heating elements, and a control device for monitoring and evaluating the first temperature sensing device and for controlling the activation state of the two heating elements. A planar first temperature sensing device covers the outside of the tank, and a second point-shaped temperature sensor is arranged on the water tank in a region of an upper edge of the upper heating element. Both temperature- 202401406

[0010] 3 / 25 detection devices are used to activate and deactivate the two heating devices, so that the lower heating device is activated first in order to start generating steam as quickly as possible.

[0011] EP 3 985 309 A discloses a cooking appliance that can control the operation of a steam supply device configured to supply steam into a cooking chamber and a heating unit configured to heat the interior of the cooking chamber, thereby maintaining a temperature in the cooking chamber at or below the boiling temperature of water during cooking.

[0012] EP 4 245 194 A1 discloses a method and an apparatus for controlling a steam generator, a steam generator, and a steam furnace. The method for controlling a steam generator comprises: sensing a target operating temperature of the steam generator; sensing a current operating temperature of the steam generator according to a preset period; determining an operating time of the water pump in the next preset period according to a relationship between the current operating temperature and the target operating temperature; and controlling the water pump to replenish water for the steam generator based on the operating time in the next preset period.This system periodically monitors the steam generator's operating temperature and adjusts the water pump's operating time accordingly. Based on the relationship between the current and target operating temperatures, the water supply is adjusted using this periodic control method, resulting in a more precise water supply for the steam generator. This avoids problems such as insufficient incoming water evaporating in time due to an excessive amount of water being added at once, and prevents the steam generator from spraying water. This ensures a continuous supply of steam that meets user requirements, thus improving the user experience. 202401406.

[0013] 4 / 25

[0014] US 11,141,017 B2 discloses a control method for a cooking appliance. The control method includes controlling the operation of the water supply pump to supply water to the steam generator; controlling the operation of the water supply pump for a period of time to supply additional water to the steam generator when the water level supplied to the steam generator reaches a certain position; controlling the operation of a drain pump to drain the water from the steam generator when the period has elapsed; and controlling the operation of a steam heater installed in the steam generator and an under-heater installed on a floor surface of the cooking appliance when the water level in the steam generator reaches the position at which the water is drained from the steam generator.

[0015] The object of the present invention is to overcome at least some of the disadvantages of the prior art and, in particular, to provide an improved way of reducing the amount of residual water remaining in the cooking chamber of a household steam treatment appliance after a steam treatment process.

[0016] This problem is solved according to the features of the independent claims. Preferred embodiments can be found in particular in the dependent claims.

[0017] The task is solved by a household steam cooking appliance, having

[0018] - a water-fillable, level-indicating evaporator,

[0019] - a water source to supply the evaporator with water,

[0020] - a controllable conveying device for directing water from the water source to the evaporator and

[0021] - a control device for controlling the conveying device so that defined quantities of water from the water source can be directed into the evaporator, wherein the household steam cooker, in particular its control device, is configured to control the evaporator in a final phase of a steam cooking process. 202401406

[0022] 5 / 25 gangs, which begins to run after reaching a set cooking time minus a defined time period for residual water use, should not be filled with water.

[0023] This household steam cooker has the advantage that only small amounts of residual water remain in the cooking chamber, meaning the user needs to wipe up little to no water after steaming. Furthermore, longer cooking times can be achieved with a given amount of water. In particular, the system utilizes the fact that the residual water usage time is designed so that the evaporator stops producing steam in the final phase because it has emptied. This results in a drier cooking chamber, so that less residual water remains at the end of the cooking process. This is achieved, for example, because escaping steam is not replenished and / or because water that has already condensed in the cooking chamber re-evaporates due to the residual heat of the cooking chamber and / or heat emitted by the empty evaporator.

[0024] A household steam cooker can be a standalone steam cooker or a combination appliance such as an oven with switchable steam cooking functionality (so-called "Added Steam").

[0025] It is a further development that the household steam cooker has a cooking chamber that can be closed by means of a door or lid. The cooking chamber can be supplied with hot steam to steam the food inside. The hot steam is generated by the evaporator.

[0026] The evaporator has a filling chamber for the liquid to be evaporated and at least one electric heating element for heating the liquid to its boiling point. The resulting steam is directed into the cooking chamber. A further development is that the heating power of the element is variable. It is a further development that the heating power of the element can be varied at a constant level by alternating heating elements. 202401406

[0027] 6 / 25 The switching on and off of the heating device is adjustable, in particular by setting a pulse duration and a duty cycle similar to pulse duration modulation.

[0028] The fact that the evaporator is a level-less evaporator means, in particular, that the household steam cooker is not designed to detect the liquid level in the evaporator. In this context, the level is defined as a positive level (greater than zero), while the evaporator running dry or boiling empty, or a completely empty filling chamber, is not included. In other words, level detection is not provided in the evaporator, although boiling dry could be detectable in a further development. Boiling dry could be implemented, for example, by means of a temperature sensor monitoring the temperature of a heating surface in contact with the liquid to be evaporated or the temperature of the electric heating element, and / or by monitoring the electric current flowing through the electric heating element.This method exploits the fact that once the liquid is completely boiled dry, the imprinted heating power is no longer reduced by the heat of vaporization of the liquid. This temperature increase also causes an increase in the resistance of an electrical resistance heating element.

[0029] It is a further development that the cooking chamber can be heated by introducing hot steam, specifically only by introducing hot steam. In this case, the cooking chamber temperature can only be raised to the temperature of the hot steam, i.e., to the boiling point of the liquid in the evaporator (approximately 100 °C for water).

[0030] A cooking process typically consists of two phases: a heating phase to raise the cooking chamber temperature to a target temperature, and a subsequent control phase once the target temperature has been reached. 202401406

[0031] 7 / 25

[0032] It is a further development that the household steam cooking appliance has at least one additional heat source to heat the cooking chamber independently of the evaporator, e.g. at least one resistance heating element, at least one induction heating surface, etc., e.g. a dedicated top or bottom heat heating element.

[0033] It is a further development that the evaporator is located outside the cooking chamber. Such an evaporator has the advantage that steam can be released into the cooking chamber with particularly precise dosage.

[0034] In one further development, the evaporator has or is a heated evaporator tray located in the base of the cooking chamber. This tray releases the steam directly into the cooking chamber or can even be considered part of the cooking chamber itself. In another further development, the evaporator tray can be refilled via a water supply channel leading into the tray from below or from the side. Alternatively, the evaporator tray can be refilled via a water supply channel opening into a side wall of the cooking chamber. In this case, the water flows from the opening of the water supply channel down the side wall to the base and from there into the evaporator tray at the bottom. For this purpose, the base of the cooking chamber can be sloped and / or equipped with a channel.

[0035] One design feature is that the water source is a water tank. The water tank can be removable by the user or permanently installed in the device. A further development is the integration of a level detection device with the water tank. This is particularly advantageous for detecting overflow and / or emptying of the water tank in a timely manner. Furthermore, this allows the flow rate of liquid into the evaporator to be quantified particularly easily and cost-effectively by measuring changes in the fill level as measured by the level detection device. 202401406

[0036] 8 / 25

[0037] One configuration involves a fixed water connection as the water source. This typically provides pressurized fresh water.

[0038] It is a design feature in which the household steam cooker, in particular its control unit, is configured to detect when the evaporator has run dry or "boiled dry" and is configured to switch off the evaporator when boiling dry is detected in the final phase. This can advantageously increase operational reliability and extend the evaporator's service life. This design is particularly advantageous if the evaporator is located outside the cooking chamber. If an evaporator located outside the cooking chamber boils dry and is not refilled, its operation no longer has a noticeable effect on the cooking chamber atmosphere. Heat is then introduced into the cooking chamber—unless the household steam cooker has at least one other heat source—due to the residual heat within the cooking chamber.

[0039] This design can also be advantageous if the evaporator is a bottom-mounted evaporator tray, because this prevents local overheating of the cooking chamber, which is particularly beneficial for delicate foods. The advantage is that, due to its residual heat, the evaporator tray can continue to evaporate any remaining water, including condensation, during the final stage of cooking. Specifically, condensate flowing back into the evaporator tray can be re-evaporated. This has the further advantage that, during the final stage, the steam content in the cooking chamber atmosphere drops only relatively slightly, while the cooking chamber walls remain comparatively dry.

[0040] It is a design feature such that the household steam cooker, in particular the control unit, is configured to keep the evaporator switched on in the final phase even if it has detected that the evaporator is running dry or has "boiled dry". This can be advantageous if the appliance is in a particular situation where the evaporator is running dry or has run dry.

[0041] 9 / 25 steamers have or are equipped with an evaporator tray, as the evaporator tray can then serve as a radiant and / or convection heating element. This offers the advantage that, due to its residual heat, the evaporator tray can evaporate the remaining water, including condensation, particularly effectively in the final phase. Specifically, condensate flowing back into the evaporator tray can evaporate again immediately. This has the further advantage that, in the final phase, the steam content in the cooking chamber atmosphere drops only relatively slightly, while the cooking chamber walls remain comparatively dry. Furthermore, a high cooking chamber temperature can be maintained even without the addition of steam.

[0042] It is also possible that the household steam cooker, and in particular its control unit, is designed to either switch off the evaporator or allow it to continue running upon detecting that the evaporator has boiled dry. This choice can be made, for example, depending on the type of cooking process, the target cooking chamber temperature, the type of food being cooked, etc.

[0043] The controllable pumping device for conveying water from the water source can, for example, include a (filling) pump, a valve, or a combination thereof. Advantageously, the pump can also pump water against gravity into the evaporator, which can be particularly useful for a water source in the form of a water tank. The flow rates can be set or defined, for example, by adjusting the pump's operating time, the valve's opening time, and / or by using a flow meter. With a water source in the form of a water tank equipped with a level sensor, the flow rate can also be adjusted, for example, by changing the water level measured by the level sensor.

[0044] It is a design feature that allows the defined time period for residual water usage to be set depending on a target cooking chamber temperature. This advantageously allows for different water consumption under different conditions. 202401406

[0045] 10 / 25

[0046] Target cooking chamber temperatures are taken into account. For example, more hot steam can be introduced into the cooking chamber to achieve a higher target cooking chamber temperature. The defined cooking time can be calculated in a training course based on the set target cooking chamber temperature.

[0047] It is a further development that the duration of residual water utilization (Atrest) is inversely proportional to the set target cooking chamber temperature (TZIEL), i.e., Atrest = f (1 / TZIEL). This advantageously allows for a simple calculation of a suitable duration of residual water utilization.

[0048] It is a further development that the time duration Atrest for residual water utilization is calculated according to the relationship Atrest = (a*ln(TziEL) + b) * VREST / PAktueii, where a and b are suitable coefficients chosen, e.g., on an experimental basis, EST is the calculated volume of residual water at the beginning of the final phase, and PAktueii is the current heating power. This configuration is particularly advantageous for use with a bottom-mounted evaporator tray.

[0049] It is a configuration in which the household steam cooker, in particular the control unit, is set up to increase the evaporator output in the final phase when the target cooking chamber temperature is in a high range, e.g., in a range up to 100 °C, or e.g., in a range between 95 °C and 100 °C. This allows the residual water to be evaporated particularly effectively in the final phase, while, by using the increased heating input when the target cooking chamber temperature is in the high range, it only affects food that can typically tolerate a high target cooking chamber temperature anyway. This configuration is particularly advantageous if the control unit is set to keep the evaporator switched on in the final phase even if it has detected that the evaporator is empty or has "boiled dry". 202401406

[0050] 11 / 25

[0051] It is a design feature in which the water source is a water tank and the household steam cooker, in particular its control unit, is configured not to issue a user notification if an empty water tank is detected during the final phase. This advantageously increases user-friendliness.

[0052] One design feature of a household steam cooker, particularly its control unit, is configured to regulate the evaporator to a target cooking chamber temperature during the final phase if the target cooking chamber temperature is below a certain value, or to operate the evaporator at a predetermined, particularly constant, power level if the target cooking chamber temperature is above the predetermined value. A further development is that the predetermined value is approximately 95 °C. This allows the residual water to be evaporated particularly effectively during the final phase, while, by operating at the highest target cooking chamber temperature, the increased heating input only affects food that typically tolerates a high target cooking chamber temperature anyway.This design is particularly advantageous if the control device is configured to keep the evaporator switched on in the final phase even if an emptying or "boiling dry" of the evaporator has been detected.

[0053] This is a design feature in which the household steam cooker is configured to fill the evaporator with a specific amount of water during the heating phase of the steam cooking process, corresponding to the amount needed for this heating phase ("initial fill"). Since the amount of water is less than a significantly excessive amount, steam generation advantageously starts earlier, which keeps the heating phase and thus the overall cooking time short. Since the amount of water is greater than a significantly insufficient amount, no refilling is required during the heating phase, which also advantageously keeps the heating phase short. 202401406

[0054] 12 / 25

[0055] This is particularly relevant if the cooking chamber contains an evaporator tray that can be filled with water through an opening in a wall, especially a side wall, of the cooking chamber, where the water inlet and a steam / air outlet are implemented via a common channel or the same opening. In this case, refilling during the heating phase can disadvantageously lead to heating pauses, which prolong the heating phase. This is based on the understanding that steam generation at high heating power can lead to significant overpressure in the cooking chamber. This overpressure can cause the water being added to the cooking chamber, which has to work against the overpressure, to flow into the air outlet instead of into the cooking chamber. This makes controlled refilling difficult or even impossible.To still allow for controlled refilling, the evaporator's heating power must be reduced or even interrupted. However, the optional vapor or air outlet can also be designed differently, e.g., as a separate outlet channel from the water inlet.

[0056] One design feature of the household steam cooker is that it continuously fills the evaporator with water during its heating phase. This also advantageously shortens the heating time and thus the overall duration of the cooking process, because heating pauses are avoided.

[0057] However, a household steam cooker can also be designed so that the evaporator is not filled continuously during the heating phase, for example, if it turns out that the specified amount of water was insufficient, perhaps because there was an above-average water consumption during the heating phase and / or because the evaporator's filling volume is not large enough for the water consumption during the heating phase. 202401406

[0058] 13 / 25

[0059] One design feature is that the amount of water supplied to the evaporator during the heating phase depends on, or is calculated based on, the target cooking chamber temperature in the cooking chamber of the household steam oven. This advantageously allows the water consumption during heating to be taken into account depending on the set target cooking chamber temperature.

[0060] It is a design in which the amount of water to be supplied to the evaporator during the heating phase comprises two different amounts of water depending on the target cooking chamber temperature, namely a smaller amount of water for a range of lower target cooking chamber temperatures, e.g. of < 90°C, and a range of higher target temperatures, e.g. of > 90°C (or < 90°C or > 90°C).

[0061] This design of the household steam cooker is such that, during the heating phase, the evaporator's heating function is only activated after a predetermined delay following the start of filling the evaporator. This advantageously prevents the incorrect detection of the evaporator boiling dry.

[0062] This design involves a domestic steam cooker that, following the heating phase, is configured to regulate the cooking chamber temperature to a target temperature by adding steam, calculates the water consumption of the evaporator, and refills the evaporator with water as needed. The control system can, for example, be a PID controller.

[0063] The problem is also solved by a method for operating a household steam cooker, which has a water-fillable, level-insensitive evaporator, a water source for supplying the evaporator with water, and a controllable conveying device for directing water from the water source to the evaporator, wherein in a final phase of a steam cooking process, which occurs upon reaching a set temperature of 202401406

[0064] 14 / 25

[0065] The cooking time, minus a defined period ("time for residual water utilization"), begins, and the evaporator is no longer filled with water. The process can be designed analogously to a household steam cooker, and vice versa, and offers the same advantages.

[0066] The properties, features and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more easily understood in connection with the following schematic description of an exemplary embodiment, which will be explained in more detail in conjunction with the drawings.

[0067] Fig. 1 shows a sketch of a household steam cooking appliance in a sectional view in side view;

[0068] Fig. 2 shows a division of a steam cooking process into different phases;

[0069] Fig. 3 shows a possible more detailed description of the steam cooking process from Fig. 2; and

[0070] Fig. 4 shows a possible detailing of the heating phase.

[0071] Fig. 1 shows a sketch of a household steam cooker 1 in a sectional side view. The household steam cooker 1 has a steam cooking drawer 3 that can be extended and retracted horizontally from a drawer housing 2. The steam cooking drawer 3 has a cooking chamber 4, the open top of which, serving as a loading opening, can be closed by means of a lid 5, which here, for example, can be pivoted.

[0072] The cooking chamber 4 can be selectively and controllably supplied with steam by means of an evaporator 6 in the form of an evaporator tray arranged on a bottom wall ("bottom") of the cooking chamber 4. For this purpose, the evaporator 6 has a tray-shaped filling chamber 6B which can be electrically heated by means of an electric heating element 6A, in which liquid, in particular water W, can be heated to boiling and the resulting steam D is released into the cooking chamber 202401406

[0073] 15 / 25

[0074] The steam is conducted into cooking chamber 4 by rising into the cooking chamber 4. In a further embodiment, the evaporator 6 can be operated with a constant electrical power, so that the amount of steam conducted into cooking chamber 4 is then mainly adjustable or definable via the operating time of the evaporator 6. In another embodiment, the electrical power is variably adjustable. Filling chamber 6B has no fill level detection.

[0075] The water W to be evaporated is supplied to the evaporator 6 via a water source in the form of a water tank 7 (removable or non-removable) and can be pumped from this tank into the bowl-shaped filling chamber 6B by means of a controllable pumping device 8. Here, for example, the pump 8 pumps the water W through a channel 11 (e.g., a hose or pipe) opening into a side wall of the cooking chamber 4. The water W then flows from the opening 11A down the side wall to the bottom of the cooking chamber 4 and from there into the bowl-shaped filling chamber 6B. In a further embodiment, the bottom of the cooking chamber 4 can be appropriately sloped and / or provided with a channel. Here, the channel 11 is designed, purely as an example, to also serve as an air outlet, for example, to vent steam L during a cooking process.

[0076] Water tank 7 can be equipped with a level detection device (not shown) that measures the water level in water tank 7.

[0077] The cooking chamber 4 is also assigned a temperature sensor 9, by means of which the cooking chamber temperature T can be sensed.

[0078] The household steam cooker 1 also has a control unit 10 which is linked to the water tank level sensor 7, the pump 8 and the temperature sensor 9 via signals and data. The control unit 10 is configured, for example, to 202401406

[0079] 16 / 25

[0080] - to detect a drop in water level, especially when the water tank 7 is empty, and if necessary to issue a corresponding message to a user, e.g. a request to refill water tank 7,

[0081] - to selectively switch the pump 8 on and off in order to direct defined quantities of water from the water tank 7 into the evaporator 6, and

[0082] - to regulate the cooking chamber temperature T to a target cooking chamber temperature TZIEL and to switch the evaporator 6 or its heating device 6A on and off appropriately.

[0083] For the last point, the control unit 10 can have a corresponding control logic, e.g. a comprehensive P, PI or PID control.

[0084] Alternatively, a household steam cooker could be, for example, an oven with a steam treatment function.

[0085] Fig.2 shows a division of a steam cooking process into different phases, namely an initial heating phase PI, a subsequent temperature control phase P2 and then a final end phase P3.

[0086] Typically, before the start of the preheating phase (PI), the food to be steam-treated is placed in the cooking chamber 4. During the preheating phase (PI), the cooking chamber 4 is heated to the target temperature (TZIEL) by adding steam. For this purpose, the evaporator 6 can, for example, be operated continuously to keep the preheating phase (PI) as short as possible. If the electrical power of the evaporator 6 is variably adjustable, it is advantageous to operate it at maximum power during the preheating phase (PI).

[0087] Once the target cooking chamber temperature TZIEL is reached, the system switches to temperature control phase P2. A cooking time IGA, set by a cooking program and / or a user, also begins. During temperature control phase P2, the cooking chamber temperature T is regulated to the target cooking chamber temperature TZIEL by means of a control algorithm implemented, for example, in the control unit 10, or programmed accordingly. 202401406

[0088] 17 / 25

[0089] The control unit 10 also calculates a specific time duration AIREST ("time duration for residual water utilization"), e.g., depending on the target cooking chamber temperature TZIEL. Calculating the AIREST time duration can involve, for example, a formulaic calculation or looking up the value in a reference table or characteristic curve. Based on AIGAR and AIREST, the control unit 10 determines the transition from the temperature control phase P2 to the final phase P3, namely after a time duration (AIGAR - AIREST) ​​following the start of the temperature control phase P2.

[0090] In the final phase P3, the evaporator 6 is no longer (newly) supplied with water, but can be operated with the water still in its filling chamber.

[0091] Fig. 3 shows a possible more detailed description of the steam cooking process PI to P3 from Fig. 2. After starting the steam cooking process PI to P3 in step SO, the heating phase PI begins in step S1 with an initial filling of the evaporator 6. Once there is enough water in the evaporator 6 to prevent the detection of boil-drying when its heating element is switched on, the heating element is activated in step S2, e.g., with continuous power. The heating element remains continuously activated, in particular, until the target cooking chamber temperature TZIEL is reached in the cooking chamber 4.

[0092] Fig. 4 shows a possible detailed representation of the heating phase PI by plotting electrical power P against time t. At the start of the heating phase PI at t = 0, pump 8 is switched on for a specific duration by being supplied with a constant operating power, as indicated by the pump 8's switch-on curve KP. This switch-on duration determines the amount of water required for the initial filling and is directly proportional to it. While pump 8 is still running, the heating device is switched on at time tl and supplied with a constant heating power, as indicated by the heating power curve KH. Once the initial filling is complete, the heating system is switched on at time tl.

[0093] 18 / 25 Once the filling of the evaporator 6 is complete, the pump 8 is switched off again at a time t2 > tl.

[0094] Returning to Fig. 3, at the start of temperature control phase P2 in step S3, the temperature control to the target cooking chamber temperature TZIEL is activated. During temperature control phase P2, the water consumption in the evaporator 6 is also calculated in step S4, and water is replenished from the water tank 7 as needed.

[0095] Upon reaching the time duration (AIGAR - AIREST) ​​after the start of the temperature control phase P2, the system switches to the final phase P3 and in step S5 first checks whether the target cooking chamber temperature TZIEL is below 95 °C or not.

[0096] If this is the case ("J"), the evaporator 6 continues to operate within the framework of temperature control in step S6. If the evaporator 6 boils dry, it is not refilled but switched off, as indicated in step S7. The steam cooking process ends in step S8 after the AIREST time has elapsed following the start of the final phase P3.

[0097] If this is not the case ("N") and TARGET > 95 °C, the evaporator 6 is operated continuously at constant power in step S9. If the evaporator 6 boils empty, it is no longer refilled but switched off, as further indicated in step S7.

[0098] Of course, the present invention is not limited to the embodiment shown.

[0099] Generally, "a", "an", etc. can be understood as singular or plural, especially in the sense of "at least one" or "one or more", etc., unless this is explicitly excluded, e.g. by the expression "exactly one", etc. 202401406

[0100] 19 / 25

[0101] A numerical specification can also include exactly the specified number as well as a normal tolerance range, unless this is explicitly excluded.

[0102] 202401406

[0103] 20 / 25

[0104] Reference symbol list

[0105] 1 household steam cooker

[0106] 2 drawer units

[0107] 3 steam cooking drawers

[0108] 4 Cooking chamber

[0109] 5 lids

[0110] 6 evaporators

[0111] 6A Electric heating element

[0112] 6B Tray-shaped filling chamber

[0113] 7 Water tank

[0114] 8 pump

[0115] 9 Temperature sensor

[0116] 10 Control unit

[0117] Channel 11

[0118] 11A Mouth

[0119] KP Pump activation curve

[0120] KH heating output curve

[0121] P Performance

[0122] P1-P3 Phase

[0123] S0-S9 process steps t time

[0124] T Oven temperature tl Time t2 Time

Claims

202401406 21 / 25 Patent claims 1. Household steam cooking appliance (1), comprising - a water (W) fillable level-detection evaporator (6), - a water source (7) to supply the evaporator (6) with water, - a controllable conveying device (8) for directing water (W) from the water source (7) into the evaporator (6) and - a control device (10) for controlling the conveying device (8) such that defined quantities of water (W) can be conveyed from the water source (7) into the evaporator (6), wherein the household steam cooking appliance (1), in particular the control device (10), is configured to - not to fill the evaporator (6) with water in a final phase (P3) of a steam cooking process (P1-P3), which begins when a set cooking time is reached minus a defined time period for residual water use.

2. Household steam cooking appliance (1) according to claim 1, wherein the defined time period for residual water utilization is adjustable depending on a target cooking chamber temperature.

3. Household steam cooker (1) according to one of the preceding claims, wherein the household steam cooker (1) is configured to detect when the evaporator (6) has boiled dry and is configured to switch off the evaporator (6) when boiling dry is detected in the final phase (P3).

4. Household steam cooker (1) according to one of the preceding claims, wherein the household steam cooker (1) is designed to keep the evaporator (6) switched on in the final phase even when the evaporator (6) has been detected to have boiled empty. 202401406 22 / 25 5. Household steam cooker (1) according to one of the preceding claims, wherein the household steam cooker (1), in particular the control device (10), is configured to increase the power of the evaporator (6) in the final phase (P3) when a target cooking chamber temperature is in a maximum range.

6. Household steam cooking appliance (1) according to one of the preceding claims, wherein the water source (7) is a water tank, to which in particular a level detection device is assigned, or a fixed water connection.

7. Household steam cooker (1) according to one of the preceding claims, wherein the water source (7) is a water tank and the household steam cooker (1) is configured to not issue a user notification when an empty water tank (7) is detected in the final phase (P3).

8. Household steam oven (1) according to one of the preceding claims, wherein the household steam oven (1) is configured to adjust the evaporator (6) to a target cooking chamber temperature in the final phase (P3) if the target cooking chamber temperature is below a certain value, or to operate the evaporator (6) with a predetermined, in particular constant, power if the target cooking chamber temperature is above the certain value.

9. Household steam cooker (1) according to one of the preceding claims, wherein the household steam cooker (1) is configured to fill the evaporator (6) with an amount of water corresponding to the requirement for the heating phase (PI) during a heating phase (PI) of the steam cooking process. 202401406 23 / 25 10. Household steam cooker (1) according to claim 9, wherein the household steam cooker (1) is configured to continuously fill the evaporator (6) with the quantity of water during the heating phase (PI).

11. Household steam cooker (1) according to one of claims 9 to 10, wherein the amount of water to be supplied to the evaporator (6) during the heating phase (PI) depends on a target cooking chamber temperature in a cooking chamber (4) of the household steam cooker (1).

12. Household steam cooker (1) according to claim 11, wherein the amount of water to be supplied to the evaporator (6) during the heating phase (PI) comprises two different amounts of water depending on the target cooking chamber temperature, namely a smaller amount of water for a range of lower target cooking chamber temperatures and a range of higher target temperatures.

13. Household steam cooker (1) according to one of claims 9 to 12, wherein the household steam cooker (1) is configured to start a heating function of the evaporator (6) only after a predetermined delay time has elapsed since the evaporator (6) has been filled during the heating phase (PI).

14. Household steam cooker (1) according to one of the preceding claims, wherein the household steam cooker (1) is configured in a temperature control phase (P2) following the heating phase (PI) to - to regulate the cooking chamber temperature (T) to a target cooking chamber temperature by adding steam, - to calculate the water consumption of the evaporator (6) and - to refill the evaporator (6) with water if necessary. 202401406 24 / 25 15. Method for operating a household steam cooking appliance (1) which - a water-fillable, level-indicating evaporator (6), - a water source (7) to supply the evaporator (6) with water, as well as - a controllable conveying device (8) for directing water from the water source (7) to the evaporator (6), wherein the process - in a final phase (P3) of a steam cooking process (P1-P3), which begins when a set cooking time is reached minus a defined time for residual water use, the evaporator (6) is not filled with water (W).

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