Method for operating a domestic appliance, and domestic appliance

Abstract

The invention relates to a method for operating a domestic appliance equipped with a plurality of sensors, at least one closed-loop control sensor of which is used as a measuring element of a closed-loop control for controlling a treatment sequence for treating items to be treated and at least one item sensor of which is used to monitor the treatment state of the item to be treated, wherein if the occurrence of a disturbance is detected during the treatment sequence, at least one pre-disturbance measured value recorded immediately beforehand by the item sensor is kept available, and when a termination of the disturbance is detected: at least one reference value is provided on the basis of the at least one pre-disturbance measured value which was kept available, at least one actual measured value of the item sensor is compared with the at least one reference value, at least one operating setting is changed in order to bring the at least one actual measured value into agreement with the at least one reference value, and when the at least one actual measured value has been brought into agreement with the at least one reference value, the treatment sequence is continued using the settings which would be present in the absence of a disturbance.

Description

[0001] Method for operating a household appliance and household appliance

[0002] The invention relates to a method for operating a household appliance equipped with at least one sensor, in which the occurrence of a fault is detected during a treatment cycle of the household appliance. The invention also relates to a household appliance configured to carry out the method. The invention is particularly advantageously applicable to cooking appliances, especially ovens and / or steam cookers.

[0003] Sensor-assisted treatment processes are being implemented more and more frequently in household appliances, particularly cooking appliances. Sensor-assisted treatment processes can be understood in particular as treatment processes that are monitored by at least one sensor and / or controlled or regulated by at least one sensor. For example, sensors are known for use in cooking processes that measure temperature, humidity or the concentration of individual gas components (e.g. O2, CO2, NH3, VOC, etc.) in a cooking chamber. The current condition of the food being cooked is determined from these measured values, for example using suitable algorithms and / or models (e.g. based on artificial intelligence methods). By means of sensor-assisted monitoring of a treatment process, for example,The treatment status of the item being treated by the household appliance can be determined, and from this, for example, the end of the treatment process can be determined. For example, during a cooking process, the degree of doneness of the item and thus—with knowledge of the associated target values—the end of cooking can be determined. Examples of such sensor-assisted treatment processes are described in EP 2 618 064 B1 and DE 10 2004 037 606 A1.

[0004] The disadvantage is that such sensors react sensitively to changes or disturbances in their environment, such as the cooking chamber atmosphere. User-induced changes in the cooking chamber atmosphere can noticeably alter the associated measurement signal and thus disrupt or even prevent proper evaluation of the cooking process.

[0005] When an oven door is opened, an exchange occurs between the cooking and ambient atmosphere. This results in a noticeable change in the sensor signal and a lasting disruption of the associated sensor logic. This can lead to a cooking process being automatically aborted. The appliance user then has the option of manually completing the cooking process based on suitable parameter settings or restarting the sensor program. The problem here is that

[0006] - the user has little or no knowledge of the progress of the cooking process to adjust appropriate parameter settings (e.g., regarding the heating type, cooking chamber temperature, and / or remaining cooking time) for the completion of the cooking process. Relevant variables relating to the progress of the cooking process may include, for example, the partial cooking stage reached, the cooking time elapsed so far, the estimated total cooking time, etc.;

[0007] - A sensor program typically assumes raw food as the starting point. Starting a program with food that is already partially cooked or cooked is not recommended. Depending on the progress of the cooking process at the time of the malfunction, the cooking result may be more or less deteriorated.

[0008] External disturbances can generally result in changes to the process environment and / or the operation of device components (e.g., a ventilation system) that are atypical for the respective treatment process and can lead to undesired treatment effects (e.g., damage to the food during a cooking process, extended cooking time, etc.) or even the termination of the sensor-driven operation. An external disturbance can be caused by the device (e.g., a malfunction) or by the device user themselves (e.g., opening a treatment room door).

[0009] To avoid unnecessary process interruptions or corrections, it is known to define a so-called grace period (e.g., comprising limits for duration, sensor values), within which the user can interact with the system without causing interruptions or other adjustments to operating parameters. (Example: with active baking sensors, the door of a cooking appliance can be opened during the first few minutes of a cooking process or sequence.) The disadvantage of the grace period is that restrictions on the scope of action are only partially lifted.

[0010] DE 10 2012 200 586 A1 discloses a method for controlling a cooking process in a cooking appliance, in which a gas concentration changing in the cooking appliance during the cooking process is determined, comprising the following steps: repeatedly measuring the gas concentration in the cooking appliance and comparing two successive measured values; detecting an extreme value of the gas concentration as a first switch-off condition; continuing the measuring process for a period of time after detecting the extreme value; and triggering a cooking appliance function if, after detecting the first switch-off condition, at least one further switch-off condition is met within the period of time.

[0011] DE 102012 210 749 A1 discloses a cooking appliance with a cooking chamber and at least one sensor for detecting at least one property of the cooking chamber, wherein the at least one sensor comprises at least one lambda probe. The cooking appliance can be configured to determine a moisture content from an oxygen content measured by the lambda probe.

[0012] DE 102004 037 606 A1 discloses a method and an arrangement for determining the course of baking, roasting and cooking processes with or without baking, roasting and cooking products containing leavening agents, wherein in the atmosphere surrounding the baking, roasting and cooking products, the carbon dioxide content CO2 and / or NH3 and / or humidity is measured as a guide gas by means of gas sensors, wherein the sensors have at least one gas-sensitive layer which, when the target gas is present, generates a measuring signal based on a change in the work function, the resistance, the capacitance or the IR absorption.

[0013] EP 0 024 798 B1 discloses a method for controlling food heating using a cooking oven, a temperature detector for detecting the surface temperature of the food, and a selection of a relative humidity detector and a gas detector for detecting a change in the environment caused by the selection of the vapor or gas emitted by the food.Gas, wherein the method comprises the steps of heating the food until a surface temperature of the food reaches a predetermined value T1 at a time t1, subsequent heating from time t1 for a time period t0 until a time t2 when the selected one among the steam and the gas causes the environment to assume a predetermined state, and further heating for a time period tR, determined by multiplying a heating time coefficient K specific to the food by the heating time period t0. DE 102012 200 304 A1 discloses a cooking appliance equipped with a cooking chamber and with at least one sensor for detecting at least one property of the cooking chamber, wherein the at least one sensor comprises at least one lambda probe. The lambda probe can in particular protrude into the cooking chamber.

[0014] DE 102007 016 501 A1 discloses that in a method for controlling a cooking process of a product in a cooking chamber of a steam cooker, moisture escaping from the product in the cooking chamber is detected at least temporarily during the cooking process by a humidity sensor over time, wherein during a measuring phase, steam is not introduced into the steam cooking chamber and the humidity sensor is evaluated. For a predetermined cooking process with fixed times for the supply of steam, the end of cooking is determined based on the evaluation of the humidity sensor during the measuring phase. Steam is introduced into the cooking chamber during a steam phase before the measuring phase, wherein the steam supply is stopped after the steam phase and before the measuring phase during a ventilation phase, and the ventilation significantly reduces the concentration of steam in the cooking chamber.

[0015] DE 102010 060 821 A1 discloses a cooking appliance for determining at least one property of a cooking chamber atmosphere, comprising: an interior space which comprises a cooking chamber for accommodating food to be cooked and at least one second chamber, in particular a pressure chamber, separated from the cooking chamber by at least one air guide element, wherein the air guide element leaves openings between the second chamber and the cooking chamber; a heating device, preferably in the second chamber; a device for circulating the cooking chamber atmosphere via the second chamber; a measuring device connected to a data processing unit, which measuring device comprises at least one sensor for determining an absorption in at least one specific spectral range of electromagnetic radiation propagating through an atmosphere in the interior space by at least one substance contained in the atmosphere, wherein at least the sensor of the measuring device, in particular the measuring device as a whole, is arranged in the second chamber.Furthermore, a method for determining at least one property of a cooking chamber atmosphere in such a cooking appliance is provided.

[0016] DE 102012 204224 A1 discloses a household appliance, in particular a cooking appliance with a lambda probe and also a method for operating a lambda probe, wherein a step-down converter is connected upstream of the lambda probe, so that a conventional lambda probe from other technical fields can also be used in the household appliance with a supply voltage that is too high for the lambda probe.

[0017] The object of the present invention is to at least partially overcome the disadvantages of the prior art and, in particular, to make sensor-driven processing sequences of a household appliance, especially a cooking appliance, more robust against external disturbances. It is also the object of the present invention to enable improved automated operation.

[0018] This object is achieved according to the features of the independent claims. Preferred embodiments can be found in particular in the dependent claims.

[0019] The object is achieved by a method for operating a household appliance equipped with a plurality of sensors, of which at least one sensor is used as a measuring element of a control loop for regulating a treatment process for treating items to be treated (hereinafter referred to as "control loop sensor" without restriction of generality) and at least one other sensor is used to monitor a treatment state of the items to be treated (hereinafter referred to as "item sensor" without restriction of generality), wherein in the method

[0020] - if a fault is detected during the treatment process, at least one pre-fault measurement value recorded immediately before the fault is detected by the at least one treatment item sensor is retained,

[0021] - and then, when the fault is detected to end:

[0022] - at least one reference value of the at least one treatment item sensor is provided based on the at least one pre-fault measurement value,

[0023] - a comparison of at least one actual measured value of the at least one treatment item sensor with the at least one reference value is carried out and

[0024] - at least one operating setting of the household appliance is changed in order to bring the at least one actual measured value into line with the at least one reference value, and

[0025] - if at least one actual measured value has been brought into agreement with at least one reference value, the treatment process is continued with the settings that would have been present without a malfunction. This process offers the advantage of a particularly rapid restoration of the condition of the item being treated to the condition prevailing without a malfunction, which in turn supports the proper continuation of the sensor-assisted treatment process and can reduce or even completely prevent malfunction-related deterioration in the treatment results. In general, the process also increases user confidence in sensor-assisted treatment processes, user satisfaction, and trust in the household appliance.

[0026] The operation of the household appliance fundamentally comprises any operating sequence ("treatment sequence") for treating items ("items to be treated"). The operation of the household appliance comprises regulating the treatment sequence by means of at least one control loop sensor, which serves as a measuring element of a control loop. The item sensor, in contrast, serves to monitor the treatment status of the item during this treatment sequence, for example, the degree of cooking of a piece of food, the degree of cleaning of laundry or dishes, etc. In particular, for the purpose of this method, the control loop sensor and the item sensor are mutually exclusive, i.e., a control loop sensor, in particular, cannot simultaneously be a item sensor, or vice versa.

[0027] The household appliance can be, for example, a cooking appliance, a laundry care appliance, or a dishwasher. The household appliance comprises, in particular, a treatment chamber for treating the items to be treated, e.g., a cooking chamber, a laundry drum, a rinsing chamber, etc.

[0028] A malfunction can be understood, in particular, as a malfunction or user intervention that may impact the outcome of the treatment process, particularly the item being treated. The malfunction may, in particular, result in a noticeable change in the atmosphere of the treatment room, which in turn may impair the treatment outcome.

[0029] The occurrence of the fault can be detected, for example, by at least one control loop sensor and / or treatment item sensor, e.g., by behavior of the associated measured values ​​that is characteristic of a fault (e.g., a sharp increase or decrease in the course of the measured values). An additional or alternative development is that the occurrence and / or termination of the fault is detected by evaluating sensor data from at least one further sensor (which is not a control loop sensor or treatment item sensor), such as a door contact switch, a light barrier, or a fuse. If, for example, a door contact switch signals that a treatment room door is open, a fault has occurred.

[0030] It is a further development that the at least one pre-fault measured value recorded immediately before the fault is detected comprises at least the last measured value recorded or measured by at least one item-to-be-treated sensor before the fault is detected, and in the case of several item-to-be-treated sensors, in particular also the last measured value in each case.

[0031] In a further development, the at least one pre-fault measurement value additionally includes at least one further measurement value recorded before the fault is detected by the at least one treatment item sensor. This offers the advantage that measured value scatter can be better limited and / or a temporal measured value profile can be provided and used, for example, for a simulation or extrapolation of a measured value reference curve (see more details below). In particular, all measured values ​​recorded from the start of the treatment process until the occurrence of the fault can be used as pre-fault measurement values, which particularly simplifies, for example, a simulation or extrapolation of a measured value reference curve.

[0032] The termination of the fault can be detected analogously to the occurrence of the fault.

[0033] The reference value corresponds, in particular, to a predefined value that an actual measured value of a treatment item sensor should reach again after the fault has ended, before returning to a "normal" treatment process. The reference value corresponds, in particular, to an actual measured value that would likely have resulted during trouble-free operation. The reference value can, in particular, correspond to at least one pre-fault measured value or be calculated from it.

[0034] The comparison of at least one actual measured value with at least one reference value is carried out, in particular, immediately after the disturbance has ended. The result of the comparison corresponds to the difference (e.g., in range / amplitude / magnitude) between the actual, disturbance-affected measured values ​​and the reference values ​​estimated for trouble-free operation. The difference therefore also represents a measure of the severity of the disturbance. For minor disturbances, the difference will generally tend to be smaller than for major disturbances.

[0035] The changed operating setting or device setting is suitable for influencing the actual measured values ​​under consideration such that they can be brought into line with the reference values, at least in principle. The operating setting or device setting can in particular comprise a change in the operation of at least one correspondingly designed functional device of the household appliance, e.g. switching on or off, changing a power level, etc. For example, a changed operating setting can change the atmosphere in the treatment room or vary it in a different way than without changing the operating setting. The changed operating setting can, for example, vary a heating output, a moisture input, a moisture content, an oxygen content, a cooling output, etc.It is therefore a possible embodiment that the at least one operating setting of the household appliance is changed by changing the control of at least one functional device of the household appliance that influences the actual measured values, in particular changing it with regard to a trouble-free treatment process.

[0036] Bringing actual measured values ​​into line with reference values ​​can also include bringing them into line within a specific, particularly predefined, tolerance range. The treatment process can then be continued with the settings (including, in particular, operating settings or device settings) that would have been in place had the fault not occurred, e.g., the settings that existed before the fault occurred.

[0037] One embodiment is such that, when the end of the fault is detected: a fault duration is determined, a comparison is made between at least one actual measured value of the at least one treatment item sensor and the at least one reference value at the same expiration time, and then, when the at least one actual measured value has been brought into line with the at least one reference value at the respective same expiration time, the treatment process is continued with the settings that would have been present without a fault. This achieves the advantage that the fault duration can be taken into account when determining the at least one reference value. This is particularly advantageous if the reference values ​​depend on the expiration time of the treatment process. The "same" expiration time corresponds in particular to the duration of the treatment process that has already elapsed or to the remaining duration of the fault-free treatment process.The duration of the disruption corresponds in particular to the period of time between the occurrence of the disruption and its cessation.

[0038] A further development is that the disruption duration Ats, in the case of a disrupted treatment process, is subtracted entirely or partially (e.g., in a certain proportion) from the already elapsed time of the disrupted treatment process in order to obtain the same time of completion. For example, if the disruption lasted Ats, the actual measured value of the disrupted treatment process at its completion time (t - Ats) can be compared with the reference value of the undisturbed treatment process at its completion time t, or, in the case of a proportion A, at its completion time (t - A • Ats).

[0039] In one embodiment, the at least one reference value corresponds to the last detected pre-disturbance measurement value. This is advantageously particularly easy to implement. This embodiment is particularly advantageous if the duration of the disturbance is short compared to the total duration of the treatment process and / or the reference value does not change or changes only slightly, at least during the disturbance duration.

[0040] In one embodiment, the at least one reference value is a value calculated based on the at least one stored pre-fault measurement value, in particular the most recently detected pre-fault measurement value. This advantageously allows deviations in the reference value over time to be easily taken into account. The calculation can be performed, for example, using a predefined formula.

[0041] In one embodiment, the at least one reference value is provided based on a measured value reference curve relating to the treatment process. This advantageously allows a suitable reference value to be reliably selected even when the reference values ​​vary significantly over the course of the process or the progress of the process.

[0042] It is a further development that the measured value reference curve relating to the treatment process corresponds to an estimated temporal progression of measured values ​​for this treatment process, even beyond the duration of the disturbance. In particular, the measured value reference curve corresponds to a "typical" progression of reference values ​​for the treatment process under consideration.

[0043] It is an embodiment that the measured value reference curve is provided in that, for the treatment process in question, a measured value reference curve that best matches the at least one pre-disturbance measured value is selected from a group of several measured value reference curves, for example in the manner of a selection of a characteristic curve from a family of characteristic curves.

[0044] It is an alternative or additional embodiment that the measured value reference curve is provided by extrapolating it from the course of several measured pre-fault measured values, in particular by simulating reference values ​​beyond the time of occurrence of the fault and / or by a curve adjustment or a curve fit of a curve with a known basic shape.

[0045] It is a further development that the measured value reference curve depicts the course of reference values ​​up to a regular end of the treatment process, in particular from the occurrence of the disturbance, in particular over the entire course of a regular treatment process.

[0046] In one embodiment, the at least one reference value, in particular the measured value reference curve, is determined depending on at least one property of the material being treated. This enables a particularly advantageous selection of the at least one reference value in order to achieve a good treatment result.

[0047] It is a further development that the treatment sequence is a treatment sequence for treating food to be cooked, e.g., a cooking sequence. In this case, the at least one reference value can be determined, for example, depending on a type of food to be cooked (e.g., meat, fish, vegetables, casserole, etc.), its weight, size, caliber, and / or a treatment type (e.g., grilling, hot air treatment, etc.). In the case of washware, the at least one reference value can be determined, for example, depending on the type of washware, such as pots, glasses, etc., and / or the wash program (e.g., "hot," "normal," "eco," "1 / 2," etc.). In the case of laundry as the treated item, the at least one reference value can be determined, for example, depending on the selected wash program.

[0048] One embodiment is that the occurrence and / or termination of the disturbance is detected by evaluating a gradient of the actual measured values, a sign of the gradient, and / or a range / amplitude of the actual measured values. In particular, a disturbance can be detected if one or more of these variables deviate from typical values ​​for a treatment process.

[0049] One embodiment is that the household appliance is a cooking appliance with a cooking chamber, and the malfunction affects a cooking process. This allows, among other things, the advantage of quickly restoring the equilibrium between food and cooking chamber atmosphere that would have existed without the malfunction. A sensor-assisted cooking process can advantageously be terminated using an original algorithm or model used before the malfunction. The application of the method reduces process interruptions and thus the need for manual follow-up operations.

[0050] This can include, for example, relieving the user of the burden of searching for suitable settings for manual operation. The associated uncertainties are avoided. Restarting a cooking process and the associated deterioration in performance, e.g. in a cooking result, can be more easily avoided. Further advantages include low costs and adaptation effort, an easy option for implementing upgrades, and potential for use in optimizing or redesigning cooking programs, e.g. after turning the food. Such a household cooking appliance can be, for example, an oven, a steam oven, a microwave oven, etc. or any combination thereof, e.g. an oven with switchable steam cooking and / or microwave function. In the case of a cooking appliance, the food sensor can also be referred to as a food sensor.It is an embodiment which can be used advantageously, particularly in the case of a cooking appliance, that the at least one food sensor has at least one food sensor from the group.

[0051] - Gas sensor, especially oxygen sensor,

[0052] - Humidity sensor,

[0053] - core temperature sensor,

[0054] - chemical sensor,

[0055] - Cooking chamber camera, whereby in a further development, a sensor can also serve as a multiple sensor, for example, a lambda probe as an oxygen sensor and / or humidity sensor. The chemical sensor can, for example, be provided to detect volatile substances that can provide an indication of the degree of cooking of a cooking product, for example, substances occurring during a Maillard reaction, in particular VOCs. The camera can be used, for example, to determine the degree of browning of the cooking product.

[0056] In a further development, the control loop sensor is a cooking chamber temperature sensor, which can be used in particular to regulate a cooking chamber temperature to a setpoint or a setpoint curve. It is also possible for an oxygen sensor and / or a humidity sensor to be used to regulate a cooking chamber atmosphere, in which case, however, they are no longer used as a food sensor. In a further development, the control loop sensor is a cooking chamber camera, using whose images, for example, the degree of browning of the food can be determined.

[0057] In one embodiment, when a cooking appliance is present, the at least one functional device comprises at least one device from the group: ambient fan, evaporator, gas cartridge and / or heating element. This makes it possible, for example, to effectively vary the cooking chamber temperature and / or the oxygen content and / or the humidity. An ambient fan can be understood in particular as a fan or ventilator by means of which gas can be conveyed from the cooking chamber into the environment (e.g. a vapor extractor) and / or ambient air can be introduced into the cooking chamber (e.g. an air supply fan). The evaporator can be an evaporator located in the cooking chamber or an evaporator located outside the cooking chamber. The contents of the gas cartridge can be introduced into the cooking chamber, for example, via a controllable valve. The heating element can, for example, comprise a bottom heat element, a top heat element, a grill element and / or a ring heater.A functional device can also be a microwave generator. Furthermore, a functional device can be a circulating fan, which can be used, for example, to quickly adjust the spatial conditions in the cooking chamber.

[0058] In addition or alternatively to switching on or off or changing a power level, etc. of the at least one functional device, at least one control parameter of the control loop can be changed, for example at least one setpoint, K value(s) of the controller, etc. The control loop still does not use the measured values ​​of the at least one material to be treated sensor as feedback variable(s).

[0059] One embodiment includes a check to determine whether the duration of the disruption has reached or exceeded a predefined threshold. If this is the case, the treatment process is not automatically continued. If this is not the case, the above-mentioned method is continued. This advantageously prevents a user from being given the impression that the treatment process can be restored or salvaged if the disruption lasts too long to continue the above-mentioned method.

[0060] The threshold may depend on the type of current treatment process and / or the type of material being treated (e.g. its type, quantity, weight, etc.).

[0061] One feature is that if the duration of the disruption reaches or exceeds the threshold, the treatment process is terminated. This prevents incorrect treatment of the item being treated particularly simply and effectively. A further feature is that in this case, a corresponding notification is issued to the user, e.g., about the presence of a disruption, the termination of the current treatment process, etc.

[0062] The procedure can be performed in the order listed above, but is not limited to this. The measured value reference curve can also be provided when the disturbance occurs, during the disturbance, or immediately after the disturbance has ceased.

[0063] The object is also achieved by a household appliance configured to perform the method described above. The household appliance can be designed analogously to the method, and vice versa, and has the same advantages. The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understandable in conjunction with the following schematic description of an exemplary embodiment, which is explained in more detail in conjunction with the drawings.

[0064] Fig.1 shows a sectional side view of a sketch of a household cooking appliance in the form of an oven;

[0065] Fig.2 shows a possible sequence of the method according to the invention using the oven from Fig.1;

[0066] Fig. 3 shows a typical measured value reference curve of an oxygen sensor for a cooking process in the oven of Fig. 1 with deviating oxygen measured values ​​in the case of temporary disturbances without use of the method according to the invention; and

[0067] Fig.4 shows, in a representation analogous to Fig.3, the course of the measured value reference curve with deviating oxygen measured values ​​in the case of temporary disturbances using the method according to the invention.

[0068] Fig. 1 shows a sectional side view of a household cooking appliance in the form of an oven 1 with a cooking chamber 3 that can be closed by a front door 2. The cooking chamber 3 can be heated by means of a top heat element 4, a bottom heat element 5 and / or a ring heater 6. The ring heater 6 is arranged near a circulating air fan 7, for example to enable hot air operation. The oven 1 can furthermore have an evaporator 8, by means of which steam can be conducted into the cooking chamber 3. The oven 1 can also have a gas-filled cartridge 9, the contents of which can be conducted into the cooking chamber 3 through a controllable valve 10. The oven 1 further comprises an air duct 11 that is coupled to a fan 12. When the fan 12 is activated, gas or vapors can be extracted from the cooking chamber 3 and / or ambient air can be forced into the cooking chamber 3.Alternatively, several fans with different functions (suction or pressure) can be used (not shown). Flaps (not shown) can also be provided to vary the cross-section of the air duct 11. The atmosphere in the cooking chamber 3 can be monitored by two sensors 13, 14, namely an oxygen content and / or a humidity content by means of a lambda probe 13 and a cooking chamber temperature by means of a temperature sensor 14. In addition, for example, a core temperature sensor, a chemical sensor and / or a cooking chamber camera (not shown) can be provided. The baking oven 1 furthermore has a data processing device in the form of a control device 15, which can control the functional units 4 to 12. The control device 15 is furthermore connected to the sensors 13, 14 in order to use, in particular to evaluate, their measurement data.

[0069] The control device 15 can be configured, in particular, to control operating sequences of the oven 1, including treatment sequences in the form of cooking sequences, but also, for example, self-cleaning sequences, etc. Treatment sequences can, in particular, also include automatic programs.

[0070] For this purpose, of the two sensors 13, 14, the (cooking chamber) temperature sensor 14 is used as a control loop sensor for regulating this cooking process in at least one cooking process. For example, the cooking chamber temperature can be regulated to a setpoint or a setpoint curve using the temperature sensor 14, with the measurement data from the temperature sensor 14 being used as feedback variables. For this purpose, certain control parameters such as K values ​​of the controller (program module), type and maximum heating outputs of the heaters 4 to 6, etc. can be specified. The lambda probe 13, in contrast, can be used as a product sensor for monitoring the treatment status of the product. For example, a treatment status (e.g., a degree of cooking) can be determined based on the humidity or oxygen measured values ​​​​determined by the lambda probe 13.The control device 15 can control the cooking process based on the treatment state, for example, change a target cooking chamber temperature, end the cooking process, etc.

[0071] The control device 15 stores – e.g., in an associated data memory – at least one of the measured values ​​of the lambda sensor 13, specifically the most recently recorded measured value or several consecutively recorded measured values, possibly even back to the beginning of the cooking process. The control device 15 is further connected to a door contact switch / door opening sensor 16 (e.g., a microswitch, Hall sensor, etc.), by means of which the open or closed state of the cooking chamber door 2 can be determined.

[0072] The control device 15 is also designed to monitor for a disturbance in the cooking process, in particular using the measured values ​​or signals of the sensors 13, 14 and / or 16, for example a door 2 being opened during a cooking process.

[0073] Fig.2 shows a possible sequence of the method using the oven 1, which is equipped with the evaporator 8.

[0074] In a first step S1, a cooking process, e.g., an automatic cooking program, is started. For this purpose, food to be cooked, e.g., baked goods, has previously been placed in the cooking chamber 3. The control device 15 regulates the cooking chamber temperature using the temperature sensor 14 and further controls the cooking process by monitoring the cooking status of the food using the lambda probe 13. The measured values ​​of at least the lambda probe 13 are stored in a data memory (not shown), specifically the most recently recorded measured value or several most recently recorded consecutive measured values, e.g., in the manner of a moving window, possibly even back to the start of the cooking process.

[0075] In step S2, the control device 15 monitors for the occurrence of a fault. This is particularly possible using the measured values ​​or signals from sensors 13, 14, and / or 16.

[0076] If a fault is detected or recognized in step S2, then in step S3 the at least one measured value(s) of the lambda probe 13 last stored before the occurrence of the fault are retained as pre-fault measured value(s) and, if necessary, stored separately or not deleted.

[0077] In step S4, the duration of the fault is calculated and checked to determine whether the duration has reached or exceeded a predefined threshold. If the duration of the fault has reached or exceeded the predefined threshold ("Yes"), the cooking process is terminated in step S5 and a user message is issued.

[0078] Otherwise ("N"), step S6 checks whether the fault has ended or not. If the fault persists ("N"), the program returns to step S4.

[0079] If it was determined in step S6 that the disturbance has ended ("Y"), the disturbance duration of the disturbance that ended before the threshold value is reached is determined in step S7, if this has not already been or can be derived from step S4.

[0080] In step S8, at least one reference value is subsequently provided from the at least one pre-fault measurement value. Thus, in one variant, at least one reference value can be provided in the form of a measurement reference curve RK (also simply referred to as a "reference curve") of reference measurements ("reference values") for the cooking process up to the fault, e.g., from historical data, simulation, curve fitting, combinations thereof, etc., in particular by extrapolation from the pre-fault measurement values.

[0081] In step S9, the deviations of the actual measured values ​​MW measured by the lambda probe 13 after the fault has ended are compared with the reference values ​​simultaneous with respect to the cooking process, e.g. with the reference values ​​of the respective measured value reference curve RK.

[0082] In step S10, at least one operating setting of oven 1 is changed based on this deviation(s) in order to bring the actual measured values ​​measured by lambda probe 13 into line with the reference values ​​at the respective same time point. For example, an increase in the oxygen value (oxygen partial pressure) in the cooking chamber 3 above the reference value detected by the lambda probe 13, or a corresponding decrease in the relative humidity in the cooking chamber 3, can be compensated for by introducing steam into the cooking chamber 3 via the evaporator 8, etc.

[0083] The cooking chamber temperature control operates independently of this and can, for example, attempt to compensate for a lower cooking chamber temperature by increasing the heating power(s). This can be influenced by the cooking chamber atmosphere, for example, by the addition of superheated steam affecting the cooking chamber temperature and / or by increased heating power increasing the release of water from the food.

[0084] In step S11, a check is carried out to determine whether the actual measured values ​​of the lambda sensor 13 have been brought into sufficiently precise agreement with at least one reference value at the same cooking time. For example, if the disturbance occurred 6 minutes after the start of the cooking process and lasted 1 minute, the agreement of the measured values ​​9 minutes after the start of the cooking process is compared with a reference value that would apply to the undisturbed cooking process for 9 minutes - 1 minute = 8 minutes.

[0085] If there is still no sufficiently precise match ("N"), the system branches back to step S10 or - as shown - to step S11.

[0086] However, if this is the case ("Yes"), the system returns to the sensor-assisted cooking process prior to the fault in step S12, particularly taking the current cooking time into account, e.g., by adjusting a timer. This can be implemented here such that the evaporator 8 is switched off again when the oxygen / humidity value has reached the reference value.

[0087] This method can - also very generally - be implemented with or without measured value reference curves, as explained in more detail below. In particular, in a further variant it is possible to set the (only) reference value to the last pre-fault measured value recorded before the fault. In this case, for example, in step S8 the reference value can be set equal to the last pre-fault measured value and then in step S9 the deviations of the actual measured values ​​MW measured by the lambda sensor 13 after the fault has ended can be compared with the reference value. In step S11 a check is carried out to determine whether the actual measured values ​​of the lambda sensor 13 have been brought into sufficiently precise agreement with the reference value. In a further development the duration of the fault does not need to be taken into account, e.g. the threshold value specified in step S4 is so short that the reference value is not changed or only changed insignificantly by the duration of the fault.

[0088] Fig.3 shows, as a plot of an oxygen content or an oxygen partial pressure p(Ü2) of the atmosphere in the cooking chamber 3 against the expiration time of a cooking process taking place, for example, in the oven 1, a typical measured value reference curve RK of an oxygen sensor, for example in the form of the lambda probe 13, with deviating oxygen measured values ​​MW in the case of temporary disturbances without use of the method according to the invention.

[0089] In order to reliably achieve and / or predict a desired cooking result using sensor-assisted cooking processes, especially cooking programs, the cooking chamber atmosphere (also referred to as the "cooking climate") should ideally exhibit a stable or food-typical profile throughout the entire cooking process or in individual cooking phases. The cooking process should therefore proceed as smoothly as possible. This is explained in more detail below using the example of a baking process for baked goods supported by a sensor using a lambda probe 13. For this purpose, it is assumed that a typical p(O2) curve represented by the measured value reference curve RK can be divided into four phases.

[0090] The oxygen value p(O2) remains constant during phase I because the O2 concentration in the cooking chamber 3 and the ambient atmosphere is the same. No evaporation of water from the raw baked goods occurs yet. Rather, the baked goods must first be heated so that the inherent water in the food can evaporate.

[0091] In Phase II, the oxygen value p(Ü2) decreases because the amount of water evaporated from the baked goods exceeds the amount of steam removed from cooking chamber 3. The food's own water evaporates over the baked goods surface and displaces oxygen from cooking chamber 3.

[0092] In Phase III, the oxygen value p(Ü2) remains constant, since the amount of water evaporated from the baked goods corresponds to the amount of steam removed from cooking chamber 3. The increasing drying of the baked goods surface reduces the evaporation rate compared to Phase II.

[0093] In Phase IV, the oxygen value p(O2) rises again, as the amount of water evaporated from the baked goods is lower than the amount of steam removed from cooking chamber 3. The evaporation of the food's own water is low, and crust formation is complete. The end of the cooking or baking process can therefore be determined by the increase in the oxygen value p(O2) in Phase IV.

[0094] To describe these phases, it can be assumed, in particular, that the amount of steam removed from the cooking chamber 3 remains at least approximately constant. It should also be noted that the oxygen value does not only depend on the ventilation state and the amount of water evaporated from the food, but can also depend on the amount of steam within the cooking chamber 3.

[0095] If, for example, the oven door 2 is opened in the middle or at the end of the baking process (which can be detected, for example, by the door opening sensor 16), the following two cases can occur - depending on the duration of this disturbance, the type of food, etc.: a) The oxygen level that would have existed without considering a disturbance is reached again (see the measured values ​​MW in Phase II for a disturbance between ts s tart and ts en d). The sensor-assisted cooking operation or process could then be started immediately after the fault has ended at time ts en d, maintaining the settings before the occurrence of the disturbance at time ts start. However, significantly more water is removed from the food through evaporation, as it is in a drier climate longer than necessary. This could lead to undesirable changes in the food. b) A higher oxygen level is reached than without disturbance (see the measured values ​​MW in Phase III for a disturbance between ts s tart and ts en d). The gradient of the rise in the fourth section or in phase IV of the baking process does not correspond to the gradient of the measured value reference curve RK and may not be detected at the same time.

[0096] Fig.4 shows, in a representation analogous to Fig.3, the course of the measured value reference curve RK with deviating oxygen measured values ​​in the case of temporary disturbances using the method according to the invention.

[0097] Here, after the disturbance has ended, the effects of the preceding disturbance are actively counteracted using the method according to the invention. For example, the oxygen values ​​p(C>2) are reduced to the corresponding reference values ​​of the measured value reference curve RK by introducing steam into the cooking chamber 3 via the evaporator 8. This can, for example, noticeably reduce the (additional) removal of water from the food caused by the disturbance. This also allows the oxygen level to be brought back to the "correct" typical value even at an advanced stage of cooking (e.g., in Phase III). The gradient of the increase in Phase IV of a baking process then corresponds again to the gradient of the measured value reference curve RK and is reliably detected.

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

[0099] The steps in Fig.2 can also run in a different order, for example step S8 between steps S3 and S4, etc.

[0100] In general, "a", "an", etc., can be understood as a singular or a plural, in particular 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.

[0101] A numerical value may also include the exact number stated as well as a usual tolerance range, as long as this is not explicitly excluded.

[0102] List of reference symbols

[0103] 1 oven

[0104] 2 doors

[0105] 3 Cooking chamber

[0106] 4 top heat radiators

[0107] 5 bottom heat radiators

[0108] 6 ring heaters

[0109] 7 recirculation fans

[0110] 8 evaporators

[0111] 9 cartridges

[0112] 10 Valve

[0113] 11 Air duct

[0114] 12 fans

[0115] 13 Lambda sensor

[0116] 14 temperature sensors

[0117] 15 Control device

[0118] 16 Door opening sensor

[0119] I - IV Phases

[0120] MW actual measured values

[0121] P partial pressure

[0122] RK measured value reference curve

[0123] S1 - S12 Process steps tSstart Time of detection of a fault tSend Time of termination of a fault t Time since the start of a cooking process

Claims

Patent claims 1. A method (S1 - S12) for operating a household appliance (1) equipped with a plurality of sensors (13, 14, 16), of which at least one control loop sensor (14) is used as a measuring element of a control loop for regulating a treatment process for treating items to be treated and at least one other item-to-treat sensor (13) is used to monitor a treatment state of the items to be treated, wherein in the method - when an occurrence of a fault is detected during the treatment process (S2), at least one pre-fault measured value recorded immediately before the detection of the fault by the at least one treatment item sensor (13) is retained (S3), - and then, when the fault is detected to end (S4): - at least one reference value of the at least one item to be treated sensor (13) is provided on the basis of the at least one pre-fault measurement value (S8), - a comparison of at least one actual measured value (MW) of the at least one material to be treated sensor (13) with the at least one reference value is carried out (S9) and - at least one operating setting of the household appliance (1) is changed in order to bring the at least one actual measured value into line with the at least one reference value (S10) and - if the at least one actual measured value (MW) has been brought into agreement with the at least one reference value (S11), the treatment process is continued with the settings that would be present without a disturbance (S12).

2. Method (S1 - S12) according to claim 1, wherein when the termination of the disturbance is detected (S4): - a disturbance duration is determined (S7), - a comparison of at least one actual measured value (MW) of the at least one material to be treated sensor with the at least one reference value is carried out at the same time (t) (S9), - if the at least one actual measured value (MW) has been brought into agreement with the at least one reference value at the same time (t) (S11), the treatment process is continued with those settings that would be present without a disturbance (S12).

3. Method (S1 - S12) according to one of the preceding claims, wherein the at least one reference value corresponds to the last detected pre-fault measurement value or is a value calculated on the basis of the at least one retained pre-fault measurement value.

4. Method (S1 - S12) according to one of claims 1 to 2, wherein the at least one reference value is provided (S8) on the basis of a measured value reference curve (RK) relating to the treatment process.

5. Method (S1 - S12) according to claim 4, wherein the measured value reference curve (RK) is provided (S8) by selecting a measured value reference curve (RK) that best fits the at least one pre-disturbance measured value from a group of several measured value reference curves (RK).

6. Method (S1 - S12) according to claim 4, wherein the measured value reference curve is provided by extrapolating it from the course of several measured pre-disturbance measured values.

7. Method (S1 - S12) according to one of the preceding claims, wherein the at least one reference value is determined as a function of at least one property of the material to be treated.

8. Method (S1 - S12) according to one of the preceding claims, in which the occurrence (S2) and / or the termination of the disturbance (S4) is detected by - a gradient of the actual measured values ​​(MW), - a sign of the gradient and / or - a stroke / amplitude of the actual measured values ​​(MW) is evaluated.

9. Method (S1 - S12) according to one of the preceding claims, in which the at least one operating setting of the household appliance (1) is changed by controlling at least one functional device (4 - 12) of the household appliance (1) influencing the actual measured values ​​in a changed manner (S10).

10. Method (S1 - S12) according to one of the preceding claims, in which the household appliance (1) is a cooking appliance having a cooking chamber (3) and the fault is a fault influencing a cooking process.

11. Method (S1 - S12) according to one of the preceding claims, in which the at least one treated item sensor comprises at least one cooked item sensor (13) from the group - gas sensor, in particular oxygen sensor (13), - Humidity sensor (13), - core temperature sensor, - chemical sensor, - Cooking chamber camera included.

12. Method (S1 - S12) according to one of claims 10 to 11, wherein the at least one functional device (4 - 12) is at least one device from the group - ambient fan (12), - evaporator (8), - gas cartridge (9), - Radiators (4 - 6), - circulating fan, - Includes microwave generator.

13. Method (S1 - S12) according to one of the preceding claims, in which it is checked whether the disturbance duration has reached or exceeded a predetermined threshold value (S5) and - if this is the case, the treatment process is not continued automatically (S6), and - if this is not the case, the method is continued (S7).

14. The method (S1-S12) according to claim 13, wherein, if the duration of the disturbance has reached or exceeded a predetermined threshold (S5), the treatment sequence is terminated and, in particular, a corresponding notification is also issued to a user (S6).

15. A household appliance (1), wherein the household appliance (1) is configured to carry out the method (S1-S12) according to any one of the preceding claims.

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