Household garage appliance with motorized longitudinally adjustable IR sensor

Description

[0001] The invention relates to a household cooking appliance comprising a cooking chamber defined by a cooking chamber wall, wherein a motor-driven, longitudinally displaceable sensor is provided, which can be moved from a rest position farther from the cooking chamber to a measuring position closer to the cooking chamber, and vice versa. The invention also relates to a corresponding method. The invention is particularly advantageously applicable to cooking appliances with a microwave function, e.g., standalone microwave ovens or ovens with a microwave function.

[0002] WO 2015 / 141207 A1 discloses a heating cooker equipped with: an infrared sensor provided on the outside of a heating chamber, which uses a plurality of infrared detection elements to detect the temperature of an object to be heated; and a direction adjustment motor that can change the direction of the infrared sensor. The heating cooker is configured so that the direction of the infrared sensor moves to a temperature detection position when temperature detection is performed, and the direction of the infrared sensor moves to a standby position when temperature detection is not performed. As a result, it is possible to prevent clouding of the lens of the infrared sensor and a temperature rise of the infrared sensor itself. For example, it is possible to maintain the infrared sensor in a state where it is possible to detect the temperature even immediately after steam heating.

[0003] US 7,696,454 B2 discloses a cooking device comprising a device housing with a burner that heats an object. A first image capture device may be provided on a side of the device housing, wherein the first image capture device may be configured to capture image information corresponding to a heat source generated by the burner. Additionally, a display may be provided on a side of the device housing to display the image information captured by the first image capture device.

[0004] EP 0 924 964 A2 discloses a microwave oven. It features an infrared sensor for detecting the temperature of food during cooking. The sensor is directed diagonally downward and backward from the upper front edge of the cooking chamber. A cover protects the sensor when it is not needed to detect the food temperature.

[0005] DE 10 2017 220 889 A1 discloses an oven, in particular a pyrolysis oven, comprising an oven which delimits a cooking chamber, an opening leading through the oven, a sensor device with at least one sensor element which is arranged on the side of the oven facing away from the cooking chamber and is directed through the opening into the oven, and a protective device with at least one additional sensor, wherein the protective device is designed to detect a critical thermal state of the sensor device by means of the at least one additional sensor and upon detection of the critical thermal state at least one protective measure can be triggered which is suitable for reducing a thermal load on the at least one sensor element of the sensor device.

[0006] DE 10 2017 220 886 A1 discloses an oven comprising an oven enclosing a cooking chamber, an outer housing, a sensor device directed into the cooking chamber, which is arranged in an interior space between the oven and the outer housing, and at least one sensor fan for ventilating the sensor device with cooling air. The sensor device comprises a tubular sensor housing open at the front, in which at least one sensor element is accommodated and whose front end is directed towards the cooking chamber. The sensor device comprises at least one viewing window arranged between the sensor element and the cooking chamber. A rear end of the sensor housing serves as an air inlet opening for cooling air. A pressure side of the sensor fan is connected to the rear end. The sensor housing has a lateral air outlet opening for the cooling air, and a suction side of the sensor fan is connected to a chamber.which is separated from the space containing the sensor device. The oven is, in particular, a pyrolysis oven.

[0007] WO 2019 / 208527 A1 discloses a heating cooking device equipped with: a heating chamber in which an object to be heated is accommodated; a wall opening, which is an opening provided in a wall of the heating chamber; a support frame provided on the outside of the heating chamber to cover the wall opening; and a camera provided on the support frame such that an imaging surface is directed toward the interior of the heating chamber through the wall opening. Furthermore, the heating cooking device is equipped with: a shutter, which can open / close to block or open the imaging surface of the camera and which is provided between the wall opening and the camera; and a fan, which blows an airflow toward the camera and the shutter.In addition, the support frame has an air duct to suck in the air flow blown out by the fan and discharge it through the wall surface opening, which has been guided to the surface, towards the heating chamber.

[0008] WO 2020 / 102538 A1 discloses a camera mechanism that can be mounted next to an opening in a cooking chamber. The opening can be covered with a movable opening cover. The camera mechanism can include a camera with a camera lens that can be inserted through the opening to physically contact the movable opening cover and move the movable opening cover out of the way, allowing the camera lens to have an unobstructed view of the food cooking in the cooking chamber. After capturing images and / or videos, the camera lens can be removed from the cooking chamber through the opening, allowing the movable opening cover to cover the opening again.

[0009] KR 2016 0069359 A relates to an electric oven and a method for controlling the same. The electric oven includes a main body including a cooking chamber and an appliance compartment; a door that selectively opens / closes the cooking chamber; a camera module that photographs the interior of the cooking chamber through a hole connected to the cooking chamber and the appliance compartment through the opening of the door; a shielding part that selectively shields the hole when the door is opened; and a control part that detects the material of a container inserted into the cooking chamber based on an image photographed by the camera module.

[0010] DE 10 2019 206 892 A1 discloses a cooking appliance having a cooking chamber (3) delimited by a cooking chamber wall, at least one sensor unit (6, 7) arranged outside the cooking chamber, and an opening (10) in the cooking chamber wall through which at least one property of the cooking chamber can be detected by means of the at least one sensor unit, wherein a motor-movable changing device is present outside the cooking chamber, the changing device is equipped with at least two sensor units for detecting at least one property of the cooking chamber, and the changing device can be adjusted by motor movement such that one of the sensor units can be brought in front of the opening at a time.A method is used for operating a cooking appliance (1), wherein during a cooking operation at least one of the sensor units is brought from a standby position into an active position by moving the changing device, a measurement is carried out there by means of this sensor unit and this sensor unit is brought back into the standby position immediately after the measurement.

[0011] US 2021 / 003289 A1 discloses an oven. It includes a housing having a cooking chamber configured to receive an object to be heated, a door configured to open and close the cooking chamber, and a ventilation path provided to extend along a wall surface of the cooking chamber in a state separated from the cooking chamber. A detector installed inside the ventilation path and including one or more sensors configured to detect information about the inside of the cooking chamber through one or more detection holes formed in the wall surface of the cooking chamber. A shutter installed inside the ventilation path and configured to open and close the one or more detection holes. A cooling fan configured to draw in outside air and blow it into the ventilation path to cool the detector and the appliance.

[0012] It is the Task The present invention aims to at least partially overcome the disadvantages of the prior art and, in particular, to provide an inexpensive and robust way of selectively exposing a sensor to a cooking chamber and protecting it from the influence of the cooking chamber.

[0013] This object is achieved according to the features of the independent claims. Preferred embodiments can be found in particular in the dependent claims and / or the description.

[0014] The object is achieved by a household cooking appliance, comprising a cooking chamber delimited by a cooking chamber wall, wherein a sleeve ("guide sleeve") with a "cooking chamber-side" front opening leading into the cooking chamber or directed towards the cooking chamber is provided on the cooking chamber wall, at least one sensor is accommodated in the guide sleeve for longitudinal displacement by a motor, and the cooking chamber-side front opening can be closed by a closure element that is motor-movable together with the at least one sensor, wherein, when the at least one sensor is in a rest position further away from the cooking chamber-side front opening, the closure element closes the cooking chamber-side front opening, and when the at least one sensor is in a measuring position further closer to the cooking chamber-side front opening, the closure element releases the cooking chamber-side front opening for the at least one sensor, wherein the sensor is an IR sensor,an inner surface of the closure element has an emissivity of almost 1 at least in its overlapping area in the IR spectral range of the sensor, the household cooking appliance additionally has a cooking chamber temperature sensor by means of which a cooking chamber temperature of the cooking chamber can be sensed, and the household cooking appliance is designed to calibrate the sensor by comparing the thermal radiation sensed on the inner surface of the closure element and the cooking chamber temperature sensed by means of the cooking chamber temperature sensor.

[0015] This cooking appliance offers the advantage of a particularly robust, yet simple and cost-effective way of exposing a sensor to a cooking chamber or a cooking chamber atmosphere, while at least thermally protecting it from the cooking chamber. The sensor and the closure element can be moved between the rest position and the measuring position, or between the closed and open positions, using a single drive. The use of the guide sleeve offers the further advantage of requiring very little space outside the installation space.

[0016] Another advantage is that the sensor can be temporarily moved into its measuring position without having to remain in this position permanently and being exposed to aggressive cooking chamber conditions such as high temperatures, an aggressive atmosphere, etc. This allows the use of sensors that can measure briefly in the measuring position (active position) without damage, but would not be able to withstand the cooking chamber conditions prevailing there permanently.

[0017] The fact that the at least one sensor has at least one IR sensor and that an inner surface of the closure element has an emissivity of almost 1 in the IR spectral range of the sensor, at least in its overlap area with the guide sleeve, can also be expressed as the closure element being designed as an almost ideal black radiator on its side facing the interior of the guide sleeve (in the closed position), whose emissivity is therefore approximately 1. The IR sensor then, in its rest position, at least partially faces this overlap area. The IR sensor can then be calibrated when the temperature of the cooking chamber is known, since it can be assumed that the temperature at the overlap area corresponds to the temperature of the cooking chamber and the IR sensor can thus correlate or calibrate the wavelength of the IR light measured at the overlap area with the cooking chamber temperature.The cooking chamber temperature is sensed using the dedicated cooking chamber temperature sensor, e.g. using a thermocouple or other measuring sensor.

[0018] The household cooking appliance can be, for example, an oven, microwave, steam treatment appliance, or any combination thereof, e.g., an oven with microwave and / or steam treatment functions. The cooking chamber wall, especially in an oven, can also be referred to as a muffle or oven tube.

[0019] A sleeve can be understood in particular as a tubular or hollow cylindrical receptacle or housing for the sensor. The sleeve is in particular straight (linear longitudinal axis), but can also be curved, for example (curved longitudinal axis). The sleeve can, for example, have a circular, oval, angular or free-form cross-section. In a further development, the guide sleeve has a diameter between 10 mm and 20 mm, in particular between 11 mm and 20 mm, in particular between 15 mm and 17 mm, very particularly of approximately 16 mm. A sensor, e.g. an IR sensor, can, for example, have a typical diameter of approximately 10 mm.

[0020] The presence of the guide sleeve on the cooking chamber wall can, in a further development, include the guide sleeve being a component manufactured separately from the cooking chamber wall and inserted into a suitable opening in the cooking chamber wall. The guide sleeve can be flush with the cooking chamber wall, in which case, in particular, the front opening of the guide sleeve on the cooking chamber side can be flush with the cooking chamber wall. Alternatively, the guide sleeve can extend through the cooking chamber wall into the cooking chamber. An advantage of this design is that the guide sleeve and the sensor can be particularly easily connected to one another separately outside the cooking chamber.

[0021] The presence of the guide sleeve on the cooking chamber wall can, in a further development, include the design of the guide sleeve as an outward-facing protrusion of the cooking chamber wall, thus representing a region of the cooking chamber wall. An advantage of this development is that it eliminates the need for separate manufacture and attachment of the guide sleeve to the cooking chamber wall. This also implicitly creates an electrical connection between the guide sleeve and the cooking chamber wall, which is particularly advantageous for cooking appliances with microwave functionality, as it makes it particularly easy to shield microwave radiation in the area of ​​the guide sleeve.

[0022] The fact that the sensor is mounted in the guide sleeve so that it can be moved longitudinally by a motor means, in particular, that the sensor can be moved by a motor along a longitudinal extension of the guide sleeve or in the longitudinal direction of the guide sleeve. In its measuring position, the sensor can be located within the guide sleeve (typically near the front opening of the guide sleeve on the cooking chamber side), flush with the front opening on the cooking chamber side, or even protrude through the front opening into the cooking chamber.

[0023] The fact that the closure element is motor-driven together with the sensor means, in particular, that the movement of the closure element occurs simultaneously with the movement of the sensor. A further development is that the closure element and the sensor are moved by the same motor. The motor can be an electric motor, for example.

[0024] The closure element is movable, in particular, between a closed position, in which it closes the front opening on the cooking chamber side, in particular rests thereon, and an open position, in which it is lifted from the front opening of the guide sleeve on the cooking chamber side. In particular, the movements of the sensor and the closure element are coordinated such that when the sensor is in its rest position, the closure element is in its closed position, and when the sensor is in its measuring position, the closure element is in its open position. The closure element can, for example, be disc-shaped.

[0025] The fact that the closure element "uncovers the front opening on the cooking chamber side for the sensor" specifically means that, when the front opening is unblocked, the sensor is enabled or enabled to take measurements of the cooking chamber and / or its contents. The sensor can therefore also be referred to as a "cooking chamber sensor." When the closure element is closed, in which case it closes the front opening on the cooking chamber side, the closure element blocks the sensor, and the sensor cannot take any practically useful measurements of the cooking chamber or its contents.

[0026] In a further development, the at least one sensor comprises at least one infrared (IR) sensor, in particular at least one IR sensor measuring in the mid-infrared range (at typical wavelengths between, for example, 3 µm and 50 µm). The fact that the closure element "opens up the front opening on the cooking chamber side for the at least one sensor" can in this case mean that the closure element is located in a spatial area outside the field of view of the IR sensor or only occupies a practically negligible peripheral area of ​​the field of view. This can also be expressed as the opened closure element opening up a view into the cooking chamber for the at least one IR sensor.

[0027] The at least one IR sensor can then, for example, capture thermal images of the cooking chamber and its contents, in a further development, in different spectral ranges if multiple IR sensors are used. For this purpose, the at least one IR sensor can be an IR camera sensor, which generates thermal images, particularly pixel-like. The use of such an openable closure element is particularly advantageous for IR sensors because alternatively usable IR-permeable protective lenses are very expensive and prone to contamination.

[0028] In an additional development, the at least one sensor comprises at least one sensor sensitive to the visible spectral range ("camera sensor"). The opened closure element, similar to the IR sensor, exposes a field of view of the at least one camera sensor for capturing images from the cooking chamber.

[0029] It is an additional development that the at least one sensor comprises at least one ultrasonic sensor.

[0030] In an additional development, the at least one sensor comprises at least one sensor configured to determine a property of the atmosphere to be measured ("atmosphere sensor"), e.g., an oxygen sensor, a humidity sensor, a sensor for detecting specific chemical substances, etc. Such atmosphere sensors, by design, must come into contact with the medium to be measured (the cooking chamber atmosphere), but do not utilize a field of view. Rather, in this case, it is sufficient for the open closure element to be raised far enough from the front opening on the cooking chamber side that the sensor is practically sufficiently exposed to the cooking chamber atmosphere.

[0031] In one embodiment, a further sleeve ("sensor sleeve") is housed in the guide sleeve so that it can be longitudinally displaced by a motor, the at least one sensor is attached to a front side of the sensor sleeve on the cooking chamber side, and the sensor sleeve is connected to the closure element via a mechanical connecting means, in particular a rod. This embodiment provides the advantage that the sensor sleeve and thus the at least one sensor can be guided particularly easily and reliably through the guide sleeve. In particular, the guide sleeve and the sensor sleeve are longitudinally displaceable relative to one another. A further advantage of the sensor sleeve is that a sensor can be attached to it easily and securely, in particular by inserting it into the front side on the cooking chamber side. A further advantage is that electrical cables of the sensor can be easily routed through the sensor sleeve.

[0032] In a further development, the sensor sleeve is designed as a rack into which a motor-driven gear engages. This advantageously provides a simple, precise, and robust option for motor-driven longitudinal displacement of the sensor sleeve within the guide sleeve. For this purpose, an outer side of the sensor sleeve can be formed, for example, with a row of teeth.

[0033] In particular, when designed as a rack, the sensor sleeve can protrude permanently (i.e. also in the measuring position) from a rear end face of the guide sleeve in order to easily ensure permanent engagement of the gear in the rack.

[0034] In another refinement, the guide sleeve can have an opening through which the gear can engage with the toothing of the sensor sleeve. This allows the sensor sleeve to be significantly shorter than if it had to protrude from the side of the guide sleeve facing away from the cooking chamber, even in the measuring position. A further advantage is that the drive unit then does not need to be located at one end of the guide sleeve, but can be arranged next to the guide sleeve to save space.

[0035] In yet another development, the sensor sleeve can have an external thread, so that the inner sensor sleeve can be moved linearly by rotating a motor-driven threaded nut that engages with the external thread. In the simplest case, the drive (motor) can be arranged at the end of the guide sleeve facing away from the cooking chamber. This can be the case, for example, with a direct drive of the sensor sleeve via a hollow motor axle (with internal spindle thread). More complicated, but fundamentally possible, would be to drive the sensor sleeve via a threaded nut that is rotatably mounted at the end of the guide sleeve facing away from the cooking chamber, which in turn is driven by a motor pinion, for example, via an external gear ring.

[0036] In one embodiment, the closure element is a pivotable closure flap. This advantageously makes it particularly easy to open up a field of view for an imaging IR or camera sensor in the measuring position. A pivot axis for the closure flap can be formed, for example, with the guide sleeve or with the cooking chamber. Transferring the movement of the sensor is particularly easy to implement if the closure flap is connected to the sensor sleeve via a pivotable rod. If the sensor sleeve is moved from the rest position to the measuring position, it presses the closure flap open via the rod. Conversely, if the sensor sleeve is moved from the measuring position to the rest position, it retracts the closure flap from its open position into the closed position.

[0037] A further development is that the closure element is firmly connected to the sensor, in particular the sensor sleeve, and is movable or is moved in a similar way to the sensor or the sensor sleeve. This further development is particularly advantageous for non-imaging or non-image-producing sensors such as humidity sensors, etc. and is particularly simple and robust to implement. To implement this further development, the closure element can be spaced from the front side of the sensor sleeve on the cooking chamber side, for example, via one or more rods or pins. If the sensor moves from the rest position to its measuring position, the closure element is moved in a similar way by the mouth opening on the cooking chamber side (in particular linearly) and thus lifted off until an opening position in front of the mouth opening on the cooking chamber side is reached.Conversely, when the sensor is moved back from the measuring position to its rest position, the closure element is repositioned onto the opening on the cooking chamber side by a corresponding (particularly linear) movement. Such a closure element can also be referred to as a closure cover. It can, in particular, be disc-shaped.

[0038] One embodiment allows the closure element to be made at least partially of a material with poor thermal conductivity. This provides the advantage that, when the sensor is in its rest position and the closure element also closes the guide tube against the cooking chamber, thermal stress on the interior of the guide sleeve in which the sensor is located can be reduced. The closure element can, for example, be made at least partially of plastic.

[0039] In one embodiment, the household cooking appliance has a microwave function, and the closure element is microwave-tight in the area where it overlaps the front opening of the guide sleeve on the cooking chamber side. This prevents microwave radiation from leaking from the cooking chamber through the front opening into the guide sleeve. This, in turn, reduces stress on the sensor and can also prevent or reduce the escape of microwave radiation from the cooking chamber. In this case, the closure element can be made of metal, for example.

[0040] In a further development, the closure element is partially made of a material with poor heat conduction and is microwave-tight in the area where it overlaps with the front opening of the guide sleeve on the cooking chamber side. This advantageously combines the advantages of thermal shielding and shielding against microwaves. For this further development, the closure element can, for example, be metallic on one side - e.g. (in the closed position) the side facing the cooking chamber - and made of plastic on its other side - e.g. (in the closed position) the side facing the guide sleeve. The metallic side can, for example, be formed by a metallic coating on a plastic base body. Alternatively, the closure element can have a sandwich structure consisting of a metallic layer and a non-metallic layer with good heat insulation.

[0041] In one embodiment, the household cooking appliance has a microwave function, the guide sleeve is electrically conductive on the casing side, and is electrically connected to the cooking chamber wall. This advantageously also ensures microwave-tightness of the guide sleeve itself, because the resulting metallic tube (guide sleeve) creates a so-called cut-off effect with a thin tube cross-section, thus preventing any microwave radiation from leaking through the guide sleeve. This applies in particular if the (inner) diameter of the guide sleeve is less than 25 mm.

[0042] The guide sleeve, in particular its outer surface, can have holes or recesses to advantageously allow an airflow through the guide sleeve, e.g., to cool the at least one sensor. To generate the cooling airflow, a conventionally installed appliance cooling fan or a dedicated fan can be used, for example. If the household cooking appliance has a microwave function, it is particularly advantageous if the holes are so small that they do not affect microwave resistance.

[0043] One embodiment provides that the closure element, in the rest position, rests hermetically on the front opening of the guide sleeve on the cooking chamber side. This advantageously provides a particularly effective seal against steam in general, preventing air flow from the cooking chamber into the guide sleeve even when the closure element is closed. This, in turn, helps protect the at least one sensor in its rest position from thermal and chemical stress. This embodiment can be implemented, for example, by the flap and / or the guide sleeve having a sealing ring or being provided with a sealing material in the contact area.

[0044] The object is also achieved by a method for operating a household cooking appliance as described above. The method can be designed analogously to the household appliance, and vice versa, and has the same advantages.

[0045] The method is then a method for operating a household cooking appliance, having a cooking chamber delimited by a cooking chamber wall, wherein a guide sleeve with a cooking chamber-side front opening opening into the cooking chamber is provided on the cooking chamber wall, a sensor is accommodated in the guide sleeve so as to be longitudinally displaceable by a motor, and the cooking chamber-side front opening can be closed by means of a closure element which is motor-movable together with the sensor, wherein in the method, by actuating a drive motor, the sensor is optionally moved from a rest position further away from the cooking chamber-side front opening to a measuring position closer to the cooking chamber-side front opening, and in the process the closure element is moved from its closed position closing the cooking chamber-side front opening into its open position releasing the cooking chamber-side front opening for the sensor, or vice versa.

[0046] Specifically, the sensor is an IR sensor, wherein an inner surface of the closure element has an emissivity of nearly 1 at least in its overlap region with an interior of the guide sleeve in the spectral range of the sensor, and a cooking chamber temperature of the cooking chamber is sensed by means of a temperature sensor, wherein the sensor is calibrated by comparing the thermal radiation sensed on the inner surface of the closure element and the cooking chamber temperature sensed by means of the temperature sensor.

[0047] Specifically, for example, in a cooking appliance, the typically homogeneous temperature distribution in the cooking chamber of a switched-off cooking appliance can be used to calibrate the IR sensor, since in this state, the cooking chamber temperature measured by the cooking appliance's temperature sensor corresponds very well with the temperature of adjacent components and thus with the temperature of the closure element. Calibration at higher temperatures is also possible, either additionally or alternatively, especially if the relationship between the cooking chamber temperature and the temperature of the closure element is known, for example, from a correlation table.

[0048] It is a further development that the at least one sensor is moved into its measuring position during a treatment process or sequence of the household appliance, such as a cooking process, in order to take measurements from the cooking chamber (images, thermal images, etc.).

[0049] A further development is that the at least one sensor is moved to its measuring position to record measurements from the cooking chamber and is moved back to its rest position after a measurement or measurement phase ("intermittent measurement"). This can be advantageous for protecting the at least one sensor, especially when continuous measurement is not necessary.

[0050] In a further development, the at least one sensor is moved to its measuring position to record measurements from the cooking chamber and is only moved back to its rest position when at least one predefined criterion indicating that the sensor may be contaminated and / or damaged is met. For example, the at least one sensor can be moved back to its rest position when the cooking chamber temperature reaches or exceeds a certain threshold.

[0051] 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 clearly understood in connection with the following schematic description of an embodiment, which is explained in more detail in connection with the drawings. Fig.1 shows a sectional side view of components of a household cooking appliance with the sensor in its measuring position; and Fig.2 shows a sectional side view of the components of the household cooking appliance from Fig.1 with the sensor in its rest position

[0052] Fig.1shows a sectional side view of components of a household cooking appliance 1 in the form of a combined baking / microwave oven. Specifically, a muffle 2 is shown, which also serves as the cooking chamber wall 3 of a cooking chamber 4. In a ceiling 3a of the cooking chamber wall 3, a dome 5 is shown, particularly in the center, for receiving a rotating antenna (not shown), via which microwaves can be fed into the cooking chamber 4. The dome 5 is separated from the actual cooking chamber 4 by a microwave-permeable cover 6. Furthermore, the cooking chamber 4 contains at least one heating element 7 for heating the cooking chamber 4 and / or for irradiating food with heat radiation, in this case a tubular top heat and / or grill resistance heating element arranged on the ceiling.

[0053] A guide sleeve 8 in the form of a straight, circular-cylindrical tube is arranged on the ceiling 3a. This tube has a flange-like bent edge 10 at its front opening 9 leading into the cooking chamber 4. The guide sleeve 8 is a separately manufactured component that extends from the cooking chamber 4 through an opening or hole in the ceiling 3a such that the edge 10 rests on the inside of the ceiling 3a and is secured there in an airtight manner, e.g., by laser welding. In the present case, the edge 10 is formed at an angle to a longitudinal axis of the guide sleeve 8, so that the installed guide sleeve 8 is inclined. This improves visibility into the cooking chamber 4 when the guide sleeve 8 is arranged off-center.

[0054] If the guide sleeve 8 is made of metal, it is electrically connected to the cooking chamber wall 8, which is also metallic. The diameter of the guide sleeve 8 is approximately 16 mm and, in a metallic or metal-coated version, is therefore impermeable to microwaves with frequency ranges around 915 MHz or 2.45 GHz, which are typical for household microwave ovens. The guide sleeve 8 can have small holes or recesses, which in particular do not affect microwave resistance. This allows for better cooling of the at least one sensor 14, since the cooling air flow of a commonly installed appliance cooling fan (not shown) can be utilized to generate an air flow through the guide sleeve 8.

[0055] A sensor sleeve 11 is accommodated in the guide sleeve 8 so as to be longitudinally displaceable by a motor. This is achieved in that an outer side of the sensor sleeve 11 is formed with a longitudinally extending row of teeth 12 and the guide sleeve 8 has a recess 20 in its outer surface or side wall through which the row of teeth 12 is exposed. The household cooking appliance 1 further comprises an electric motor 21, onto whose drive shaft a gear 22 is mounted, the gear rim of which in turn engages through the recess 20 into the row of teeth 12. By actuating the electric motor 21 and correspondingly rotating the gear 22, the sensor sleeve 11 can be moved between two end positions, as indicated by the double arrow P1, namely between the measuring position shown and a position described in more detail below and in Fig.2 shown resting position.

[0056] A sensor, in this case an IR sensor 14, is mounted on the cooking chamber-side end face 13 of the sensor sleeve 11. In the variant shown, it is flush with the cooking chamber-side end face 13. Thus, the IR sensor 14 is also housed in the guide sleeve 8 so that it can be longitudinally displaced by a motor. As shown for the measuring position, it can be moved out of the guide sleeve 8 outside of its rest position.

[0057] The IR sensor can, for example, have a diameter of approximately 10 mm, which then corresponds to the inner diameter of the tubular sensor sleeve 11

[0058] A rod 15 is rotatably connected to the sensor sleeve 11 and protrudes toward the cooking chamber. On the other side, the rod 15 is connected to a closure flap 17 pivotably mounted on the edge 10 via a hinge 16, thereby enabling the closure flap 17 to move, as indicated by the double arrow P2. More precisely, the other end portion of the rod 15 is rotatably connected to a projection 19 extending upright in an overlapping area 18 of the closure flap 17.

[0059] In the measuring position of the IR sensor 14 shown, the closure flap 17 with the rod 15 is pivoted so far away from the front side 13 of the sensor sleeve 11 that the front opening on the cooking chamber side is exposed to the IR sensor 14 and the closure flap 17 is no longer in the field of view F of the IR sensor 14. The IR sensor 14 can therefore record a thermal image of the cooking chamber 4 without being disturbed by the closure flap 17.

[0060] If the sensor sleeve 11 is retracted from the measuring position into the guide sleeve 8, the IR sensor 14 is also retracted into the guide sleeve 8 until it reaches a rest position further away from the cooking chamber 4. The IR sensor 14 and the closure flap 17 can thus be moved together by the electric motor.

[0061] In general, the sensor sleeve 11 can be moved between the operating and rest positions. A further development is that the sensor sleeve 11 can also be moved to intermediate positions.

[0062] When the sensor sleeve 11 is retracted into the guide sleeve 8, it pulls the rod 15 into the guide sleeve 8, causing the closure flap 17 to pivot about the hinge 16 toward the front opening 9 on the cooking chamber side. This closing movement can be continued until the IR sensor 14 is in its rest position, in which case the closure flap 17 is in its closed position, covering the front opening 9 on the cooking chamber side. The cover area 18 then points into the guide sleeve 8. The projection 19 is also housed in the guide sleeve 8.

[0063] The closure flap 17 or the edge 10 can be designed to provide a seal, e.g., by providing a sealing ring (not shown) or a sealing coating. This reliably prevents air from entering the guide sleeve 8 in the rest position.

[0064] The closure flap 17 can, in particular, be disc-shaped and, for example, be metallic (e.g., coated or lined) on its side facing into the cooking chamber 4 in the rest position ("outside"), and be made of a poorly heat-conducting material, e.g., plastic, ceramic, micanite, or the like, on its inner side facing into the guide sleeve 8 in the rest position, which corresponds to the cover area 18. The metallic layer also makes it particularly effective in preventing microwaves from entering the guide sleeve 8.

[0065] In particular, the cover region 18 may have a surface with an emissivity close to 1. In this case, the cover region 18, which is located in the field of view of the IR sensor 14 in its rest position, may be used to calibrate the IR sensor 14 in its rest position.

[0066] During a cooking process, the household cooking appliance 1 can be operated, for example, as follows: In one variant, thermal images are recorded practically continuously or at short intervals from the cooking chamber 4 and thus also from the food located in the cooking chamber 4. For this purpose, at the start of the cooking process, the electric motor is actuated in such a way that the sensor sleeve 11 is moved from the retracted rest position forwards towards the cooking chamber 4 and, in doing so, pushes open the closure flap 17, which was previously in its closed position, via the rod 15, so that this flap lifts off the front opening 9 on the cooking chamber side. The sensor sleeve 11 is moved until the Fig.1shown measuring position is reached. In the measuring position, the thermal images are recorded by the IR sensor 14. The sensor sleeve 11 is retracted in the reverse direction into the guide sleeve 8, in particular if (a) the IR sensor 14 is no longer required, e.g. because the cooking process has ended, and / or (b) the IR sensor 14 could be damaged, e.g. because the cooking chamber temperature has reached or exceeded a predetermined threshold value. In the rest position, the IR sensor 14 is protected from the cooking chamber 4 by the closing flap 17, specifically against microwaves, thermal radiation and a cooking chamber atmosphere. In addition, the IR sensor 14 is comparatively far away from the cooking chamber 4 in the rest position, so that its thermal load is also reduced.

[0067] In another variant, thermal images are captured at longer intervals. For this purpose, the IR sensor 14 only needs to be moved from its rest position to its measuring position for each image capture and is returned to its rest position after the capture.

[0068] 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.

[0069] 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. List of reference symbols

[0070] 1 Household cooking appliance 2 Muffle 3 Cooking chamber wall 3a Ceiling 4 Cooking chamber 5 Dome 6 Cover 7 Heating element 8 Guide sleeve 9 Front opening on the cooking chamber side 10 Edge 11 Sensor sleeve 12 Gear rack 13 Front side 14 IR sensor 15 Rod 16 Hinge 17 Covering flap 18 Covering area 19 Projection 20 Recess in the guide sleeve 21 Electric motor 22 Gear P1 Double arrow P2 Double arrow

Claims

1. Household cooking appliance (1) comprising a cooking compartment (3) delimited by a cooking compartment wall (4), wherein - a guide sleeve (8) provided on the cooking compartment wall (3) has a cooking compartment-side end opening (9) which opens into the cooking compartment (4), - at least one sensor (14) is housed in the guide sleeve (8) so as to be longitudinally movable by motor power and - the cooking compartment-side end opening (9) can be closed by means of a closure element (17) which can be moved by motor power together with the at least one sensor (14), wherein - when the at least one sensor (14) is located in a rest position further away from the cooking compartment-side end opening (9), the closure element (17) closes the cooking compartment-side end opening (9), and - when the at least one sensor (14) is located in a measuring position nearer to the cooking compartment-side end opening (9), the closure element (17) clears the cooking compartment-side end opening (9) for the at least one sensor (14), - the household appliance (1) also has a cooking compartment temperature probe, by means of which a cooking compartment temperature of the cooking compartment (4) can be detected, characterised in that - the sensor (14) is an IR sensor (14), - an inner surface of the closure element (17) has an emissivity of approximately 1 in the IR spectral range of the sensor (14) at least in its overlapping region (18), - the household appliance (1) is configured to calibrate the sensor (14) by comparing the thermal radiation detected on the inner surface of the closure element (17) and the cooking compartment temperature detected by means of the cooking compartment temperature probe.

2. Household cooking appliance (1) according to claim 1, wherein a sensor sleeve (11) is housed in the guide sleeve (8) so as to be longitudinally movable by motor power, the at least one sensor (14) is attached to a cooking compartment-side end face of the sensor sleeve (11), and the sensor sleeve (11) is connected via a rod system (15) to the closure element (17).

3. Household cooking appliance (1) according to one of the preceding claims, wherein the closure element (17) is a pivotable closure flap.

4. Household cooking appliance (1) according to one of the preceding claims, wherein the closure element (17) consists of a poor thermally conductive material.

5. Household cooking appliance (1) according to one of the preceding claims, wherein the household cooking appliance (1) has a microwave function and the closure element (17) is configured so as to be microwave-tight in its overlapping region (18) with the cooking compartment-side end opening (9) of the guide sleeve (8).

6. Household cooking appliance (1) according to one of the preceding claims, wherein the household cooking appliance (1) has a microwave function, the guide sleeve (8) is configured so as to be electrically conductive on the lateral surface thereof and is electrically connected to the cooking compartment wall (3).

7. Household cooking appliance (1) according to one of the preceding claims, wherein in the rest position the closure element (17) is positioned in an airtight manner on the cooking compartment-side end opening (9) of the guide sleeve (8).

8. Method for operating a household cooking appliance (1) comprising a cooking compartment (4) delimited by a cooking compartment wall (3), wherein a guide sleeve (8) provided on the cooking compartment wall (3) has a cooking compartment-side end opening (9) which opens into the cooking compartment (4), a sensor (14) is housed in the guide sleeve (8) so as to be longitudinally movable by motor power, and the cooking compartment-side end opening (9) can be closed by means of a closure element (17) which can be moved by motor power together with the sensor (14), wherein in the method, by actuating a drive motor, - the sensor (14) is selectively moved out of a rest position further away from the cooking compartment-side end opening (9) to a measuring position nearer to the cooking compartment-side end opening (9), and at the same time the closure element (17) is moved out of its closed position closing the cooking compartment-side end opening (9) into its open position clearing the cooking compartment-side end opening (9) for the sensor (14), or vice versa, - and wherein the sensor (14) is an IR sensor (14), an inner surface of the closure element (17) has an emissivity of approximately 1 in the IR spectral range of the sensor (14) at least in its overlapping region (18), and a cooking compartment temperature of the cooking compartment (4) is detected by means of a temperature probe, - wherein in the method the sensor (14) is calibrated by comparing the thermal radiation detected on the inner surface of the closure element (17) and the cooking compartment temperature detected by means of the temperature probe.

9. Method according to claim 8, in which the sensor (14) is calibrated when the cooking appliance (1) is switched off.

10. Method according to one of claims 8 or 9, in which the sensor (14) is calibrated via an allocation table which indicates how well the cooking compartment temperature and the temperature of the closure element relate to one another.