Sensor device for measuring air humidity inside a cooking compartment of a cooking appliance, cooking appliance and method for measuring of air humidity inside a cooking compartment of a cooking appliance

Abstract

A sensor device (100) for measuring air humidity inside a cooking compartment (CD) of a cooking appliance (CA), comprises a humidity sensor (1) having a sensor housing (5) and a sensing element (7); a sensor holding part (4) having a holding structure (4a) which can be arranged at a wall (SW) of the cooking appliance (CA) and outside the cooking compartment (CD) and further having a sensor cover (3) which extends into the interior of the cooking compartment (CD) through an opening in the wall (SW) and the sensor cover (3) further having a sensor opening (3a), and wherein the sensor housing (5) is placed inside the sensor cover (3) in a rotatable manner such that the sensor housing can be rotated between a sensing position and a closed position such that the opening (5a) at least partly overlaps with the sensor opening (3a) to expose the sensing element (7) to the interior of the cooking compartment (CD) in the sensing position and that the opening (5a) is fully covered by the sensor cover (3) to cover the sensing element (7) towards the interior of the cooking compartment (CD) when in the closed position; and a sensor rotating part (2) having an actuator (11) and a rotating arm (10) and a supporting structure (2a) to which the actuator (11) is mounted, wherein the supporting structure (2a) can be arranged at a wall (SW) of the cooking appliance (CA) and outside the cooking compartment (CD) and in a vicinity of the sensor holding part (4) such that the rotating arm (10) is linked both to the actuator (11) and to the humidity sensor (1) for rotating the sensor housing (5) between the sensing position and the closed position by the actuator (11) over the rotating arm (10).

Description

[0001] SENSOR DEVICE FOR MEASURING AIR HUMIDITY INSIDE A COOKING COMPARMENT OF A COOKING APPLIANCE, COOKING APPLIANCE AND METHOD FOR MEASURING OF AIR HUMIDITY INSIDE A COOKING COMPARTMENT OF A COOKING APPLIANCE

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a sensor device for measuring air humidity inside a cooking compartment of a cooking appliance, to a cooking appliance having a sensor device for measuring air humidity inside a cooking compartment and to a method for measuring of air humidity inside a cooking compartment of a cooking appliance.

[0004] BACKGROUND OF THE INVENTION

[0005] For cooking appliances humidity sensors became a trend for the home appliances industry, wherein most of the best steam ovens on the market have some type of humidity sensors which can detect relative or absolute humidity levels inside the oven cavity. In another example the humidity levels can be calculated from another quantity such as temperature and / or oxygen level of the air in the oven cavity.

[0006] A main benefit of having a humidity senor in the oven cavity is that it can improve a humidity regulation during cooking and can be used as a feedback component for the steam regulation system. In typical such cycles once the desired humidity level is reached the device for generating steam can stop working or adjust the humidity level to a desired level.

[0007] When the humidity level drops to a predetermined level the steam generating device generates the steam again, in order to maintain a desired humidity level. By such operation the system can reduce excessive water usage. Therefore, by using the humidity sensor a reduction of water consumption can be reached when compared to systems without a humidity sensing system. As currently on the market, most of the steam ovens can support maximum cooking temperatures of 250 - 275 °C and humidity sensors are usually not used in pyrolytic ovens.

[0008] Regarding the existing solutions a main technical challenge remains to develop a humidity sensor which can withstand pyrolytic temperatures (400 - 500°C) but also at the same time can be also suitable for the microwave usage.

[0009] Document EP 2848868 A1 describes a baking oven with a humidity sensor and air management system.

[0010] SUMMARY OF THE INVENTION

[0011] It is an object of the invention to improve the accuracy of measuring humidity of the air inside the cooking compartment of a cooking appliance. Further, the sensor device itself can be protected against cooking conditions which may harm the sensor device.

[0012] The object is solved by the subject-matter of the independent claims.

[0013] The present invention pertains a sensor device for measuring air humidity inside a cooking compartment of a cooking appliance according to claim 1, to a cooking appliance having a sensor device for measuring air humidity inside a cooking compartment according to claim 9 and to a method for measuring of air humidity inside a cooking compartment of a cooking appliance according to claim 14.

[0014] Preferred embodiments are subject of the dependent claims.

[0015] According to the invention the sensor device for measuring air humidity inside a cooking compartment of a cooking appliance comprises a humidity sensor having a sensor housing and a sensing element enclosed inside the sensor housing, wherein the sensor housing has an opening at a region where the sensing element is positioned such that a sensing side of the sensing element is exposed through the opening. Further, the sensor device comprises a sensor holding part having a holding structure which can be arranged at a wall of the cooking appliance and outside the cooking compartment and further having a sensor cover which extends into the interior of the cooking compartment through an opening in the wall when the holding structure is arranged outside the wall and the sensor cover further having a sensor opening, and wherein the sensor housing is placed inside the sensor cover in a rotatable manner such that the sensor housing can be rotated between a sensing position and a closed position such that the opening at least partly (or fully) overlaps with the sensor opening to expose the sensing element to the interior of the cooking compartment in the sensing position and that the opening is fully covered by the sensor cover to cover the sensing element towards the interior of the cooking compartment when in the closed position. Further, the sensor device comprises a sensor rotating part having an actuator and a rotating arm and a supporting structure to which the actuator is mounted, wherein the supporting structure can be arranged at a wall of the cooking appliance and outside the cooking compartment and in a vicinity (for example few centimeters close to or directly in contact) of the sensor holding part such that the rotating arm is linked both to the actuator and to the humidity sensor for rotating the sensor housing between the sensing position and the closed position by the actuator over the rotating arm.

[0016] The sensor device is able to detect a humidity level within a cooking compartment, for example an oven cavity, during a cooking process.

[0017] The sensor housing can be formed from a metal or any other material which can withstand pyrolytic oven functions.

[0018] The sensing element can be embedded into the sensor housing. Further, the sensing element can be exposed through the opening in the sensor housing and through the opening in the sensor cover to air from the cooking compartment. The walls can be the lateral walls or the rear wall of the cooking compartment and the opening in the particular wall can be huge enough that the sensor cover and the sensor housing inside the sensor cover can extend through said opening in the wall. The sensor holding structure can be mounted to the wall at its external side (external to the cooking compartment and outside the hot air for cooking and mounted in the sense of screwed to the wall or another mounting structure or clipped or fixed in another suitable way).

[0019] The rotating arm can be a bar which translates force from the actuator, for example in one dimension, towards a handle part of the sensor housing, where the one dimensional force along the actuating direction can be translated to a rotation of the sensor housing, for example such that a pin at the end of the sensor housing can slide along a slot in the rotating arm producing a force transfer inside a plane perpendicular to the axis of rotation of the sensor housing.

[0020] According to a further embodiment of the sensor device it further comprises a temperature sensor which is arranged at the holding structure and / or at a wall of the cooking appliance and outside the cooking compartment such that the temperature sensor can extend into the interior of the cooking compartment through an opening in the wall.

[0021] The temperature sensor can have a bar shape and extend through the sensor holding structure into the interior (and through the particular opening in the wall) of the cooking compartment.

[0022] According to a further embodiment of the sensor device the sensor housing and the sensor cover have at least partly a cylindrical shape and extend coaxially (to each others) and the sensor housing is rotatable around the cylindrical axis.

[0023] According to a further embodiment of the sensor device the humidity sensor has a handle at a first end of the sensor housing facing away from the sensor cover and being linked to the rotating arm, wherein a cable and / or electric contact is connected to the humidity sensor through the first end.

[0024] According to a further embodiment of the sensor device the sensing element has a sensing side and a heating side which is opposite the sensing side and wherein the sensing side comprises a substrate and a sensing printing on the substrate and the sensing printing having a changing resistivity when contacting humid air and the heating side comprises a heating element for heating the sensor housing and the sensing element and wherein the sensing element further comprises a temperature sensing part, which is embedded in the substrate or placed on the sensing side and between or adjacent to the sensing printing.

[0025] The sensing side can be flat. The heating element and the temperature sensing part can be a printing in or on the substrate itself. The temperature sensing part can be used for evaluat- ing / measuring a temperature of the housing and the need and / or effect of lowering condensate on the sensing printing.

[0026] The heater can help reducing condensate and dirt on the sensing printing which can effect the measuring process and at the same time enables temperature regulation based on measurements from the temperature sensing part and heating of the sensing printing during the measurement process. Since the sensor device for detecting the humidity in the air can use capacitive technology for measurements it should be always protected from the fats and oils in the air. Therefore the rotation of the sensor housing inside the sensor cover as special mechanism is provided so that sensor can be protected when not used.

[0027] According to a further embodiment of the sensor device the actuator is a wax-motor for providing a linear force to the rotating arm for providing a translatoric force to or away from the humidity sensor from a direction perpendicular to a longitudinal extent of the sensor housing to a rotational force component for rotation of the sensor housing around its longitudinal axis.

[0028] The linear force can be understood as linear along a direction towards or from the sensor housing (its end where the translatoric components act) and in one dimension. The rotation arm can be movable only in this linear direction and has the role of a linear translatoric arm.

[0029] According to a further embodiment of the sensor device the sensor rotating part comprises a return spring which is linked to the rotating arm and to the supporting structure such that the return spring pulls the rotating arm against a linear direction of the force provided by the actuator. The return spring can act against the direction of the force from the actuator along the rotation arm in order to push the rotating arm (or pull it) after the actuator is not active any more or to support the actuator at least along one direction for rotation of the sensor housing to sensing or closed position.

[0030] According to a further embodiment of the sensor device the sensor rotating part is (physically) connected to the sensor holding part.

[0031] According to the invention the cooking appliance comprises a cooking compartment with walls; a sensor device according to the invention, which is mounted at a wall (which can be a lateral wall or a backwall / rear wall) of the cooking compartment such that the sensor holding part with the holding structure is arranged at the wall of the cooking appliance and outside the cooking compartment and further the sensor cover extends into the interior of the cooking compartment through an opening in the wall when the holding structure is arranged outside the wall wherein the sensor housing is placed inside the sensor cover in a rotatable manner and extends with the sensor cover into the interior of the cooking compartment and the sensor rotating part having the actuator and the rotating arm and the supporting structure to which the actuator is mounted and wherein the supporting structure is arranged at the wall of the cooking appliance and outside the cooking compartment. The cooking appliance further comprises a controller, which is connected to the sensing element and to the actuator and to a position switch and which controller is configured to sense (and evaluate) a relative and / or absolute humidity of the air in the cooking compartment from a change in resistance at the sensing element and to provide a force from the actuator to the rotating arm thereby rotating the sensor housing between a sensing position and a closed position such that the opening at least partly overlaps with the sensor opening to expose the sensing element to the interior of the cooking compartment in the sensing position and that the opening is fully covered by the sensor cover to cover the sensing element towards the interior of the cooking compartment when in the closed position. The position switch can be configured such that it can recognize when the rotation arm reaches a particular position which can be recognized as the position at which the sensor housing is rotated to a sensing position (open position). When the position switch recognizes said position of the rotation arm it can trigger a signal to the controller and set a start for measuring humidity. On the other hand or in addition, the position switch can recognize a position of the rotation arm at which the sensor housing is rotated to the closed position (or both).

[0032] According to a further embodiment of the cooking appliance the cooking appliance is a built-in oven or a standalone oven with steam function and / or with pyrolytic function and / or a microwave or any combination thereof.

[0033] The cooking appliance can have a heating cavity as cooking compartment.

[0034] According to a further embodiment of the cooking appliance the controller is further configured to operate the heating element such to heat the sensing side and lower or evaporate a condensate from the humid air on the sensing printing and / or such that the sensor housing and / or the sensor cover are heated up to soften grease between the sensor housing and the sensor cover such to keep the sensor housing rotatable against grease between the sensor housing and the sensor cover.

[0035] According to a further embodiment of the cooking appliance the wall is a rear wall (backwall) of the cooking compartment and wherein a fan with a fan elise is located at the rear wall and a fan cover with an opening or holes in its central region for the fan is attached to the rear wall such that the fan elise is located between the rear wall and the fan cover for sucking air from the interior of the cooking compartment and wherein the fan cover has ventilation holes at edge regions of the fan cover through which ventilation holes a part of the humid air from the fan enters again the interior of the cooking compartment and wherein the opening in the rear wall through which the sensor cover and the sensor housing extend into the interior of the cooking compartment is located adjacent to at least one of the ventilation holes and wherein the sensor opening is directed towards the at least one of the ventilation holes. The fan cover can have at its edge region the opening for the sensor cover (and the sensor housing) through which the sensor cover and the sensor housing can extend into the interior of the cooking compartment. The configuration can therefore be such that the rear wall can have the opening for the sensor cover and for the sensor housing and the fan cover can be placed with the corresponding opening for the sensor cover at the opening in the rear wall such that the sensor cover and the sensor housing can extend through both the rear wall and through the fan cover into the cooking compartment (and next to the ventilation holes). Instead of the ventilation holes there can be only a thin gap between the fan cover and the rear wall where the air to be measured can enter the interior of the cooking compartment and the sensor cover with the sensor housing can extend through the rear wall right next to this gap.

[0036] The fan can be a typical fan known from ovens. The ventilation holes can be directed to a lateral wall and thereby to the sensor housing which can be located at a lateral edge of the rear wall or at the lateral wall.

[0037] According to a further embodiment of the cooking appliance the controller is further configured to adjust a steam function and thereby a value of relative or absolute humidity in the interior of the cooking compartment due to a measured relative or absolute air humidity at the sensing element and due to a cooking programme.

[0038] According to the invention the method for measuring of air humidity inside a cooking compartment of a cooking appliance comprises the step of determining S1 a prevailing condition inside the cooking compartment whether to measure the air humidity at a particular time or time-period inside the cooking compartment by a humidity sensor which has a sensing element that can be exposed to the air inside the cooking compartment, wherein the prevailing condition is measured by a temperature sensor inside the cooking compartment and / or evaluated by a user and / or by a cooking programme. The method further comprises the step of keeping a sensor housing of the humidity sensor in a sensing position or rotating the sensor housing to a sensing position and measuring relative and / or absolute humidity of the air in the cooking compartment by a sensing element of the humidity sensor if the prevailing condition inside the cooking compartment is determined as suitable for measuring air humidity inside the cooking compartment and / or keeping the sensor housing in a closed position or rotating the sensor housing to the closed position if the prevailing condition in-side the cooking compartment is determined as not being suitable for measuring air humidity inside the cooking compartment, wherein the rotating is performed by a mechanism which is placed outside the cooking compartment. It can be evaluated whether the prevailing condition is suitable due to measured or evaluated (foreseen from oven operation over time or computed due to a model) with regard to particular parameters like temperature in the cooking compartment, time of operation and others (parameters can match a predefined range therefore). In the closed position the sensing element can be completely covered by the sensor cover.

[0039] According to a further embodiment of the method the sensor housing is placed inside the sensor cover in a rotatable manner such that the sensor housing can be rotated between the sensing position and the closed position such that an opening of the sensor housing at least partly overlaps with the sensor opening of a sensor cover to expose the sensing element placed inside the sensor housing to the interior of the cooking compartment in the sensing position and that the opening is fully covered by the sensor cover to cover the sensing element towards the interior of the cooking compartment when in the closed position, wherein the sensor cover extends into the cooking compartment and the sensor housing is placed inside the sensor cover.

[0040] According to a further embodiment of the method the prevailing condition is suitable for measuring air humidity inside the cooking compartment if a temperature of air inside the cooking compartment is lower or equal to 1000C and / or if a cooking programme with a low greasy aerosol level and / or if steam cooking is chosen. The temperature can be measured by a temperature sensor which also can extend into the cooking compartment.

[0041] According to a further embodiment of the method the prevailing condition is not suitable for measuring air humidity inside the cooking compartment if a temperature of air inside the cooking compartment is higher than 100 ° C and / or if a cooking programme with a high greasy aerosol level is chosen and / or if a pyrolytic cycle is chosen (by a programme and / or user).

[0042] According to a further embodiment of the method the sensing element has a sensing side and a heating side which is opposite the sensing side and wherein the sensing side comprises a substrate and a sensing printing on the substrate and the sensing printing having a changing resistivity when contacting humid air and the heating side comprises a heating element for heating the sensor housing and the sensing element and wherein the sensing element further comprises a temperature sensing part, which is embedded in the substrate or placed on the sensing side and between or adjacent to the sensing printing and the heating element is operated such to heat the sensing side above a predetermined temperature (and for a predefined time, for example 30s) which is monitored by the temperature sensing part and lower or evaporate a condensate from the humid air on the sensing printing and / or such that the sensor housing and / or the sensor cover are heated up to a predetermined temperature which is monitored by the temperature sensing part (and by the controller) to soften grease between the sensor housing and the sensor cover such to keep the sensor housing rotatable against grease between the sensor housing and the sensor cover.

[0043] The rate of evaporation can be estimated by assumption of a time and / or temperature needed for effective evaporation at the sensing printing.

[0044] According to a further embodiment of the method the method is performed on a cooking appliance according to the invention.

[0045] With the method also opening and closing sequences of the sensor device can be performed when rotating the sensor housing to the sensing and / or to the closed position.

[0046] A main aim of the mechanism is to protect the sensing element from grease and oils in the air, which are generated during the cooking process and are spread around the oven cavity as the aerosol. If the grease covers the sensing surface / printing (for example comprising a metaloxide), the sensing element may not be able to come in contact with enough humid air for a useful measurement. In order to lower the amount of dirt or fat or grease or other aerosols on the sensing element the latter can be protected during the baking of greasy food, for example or during cooking programms which are not suitable for measuring air humidity. The concept of closing can also extend the lifetime of the sensor. It is known that greasy aerosol is, in the most cases, generated on higher temperatures, like grilling, etc. and baking temperatures below 100°C are not critical for grease aerosol generation what means that during the steaming cycles, which are in mostly performed on 100°C, the sensor housing can be in the opened (sensing) position.

[0047] Further, the mechanism can ensure that the sensor is protected (closed) during a pyrolytic cycle, baking cycles above 100°C, and any other cycle during which is not required to measure the steam. In most cases the sensor is being opened only during steaming program at 100°C, or below. When sensor is closed, a measurement is not done, since it doesn't reflect real conditions inside the oven cavity.

[0048] By the heater in the sensing element a heating of the sensor housing can be achieved to soften the grease. During the cooking of the food which contains a higher amount of grease the grease in the aerosol can pile up on the inner side of the sensor cover and outer side of the sensor housing. If the temperature is increased, for example during the pyrolytic cycle, grease on the surface can harden or even burn, which may cause the blockage of the sensor's rotation. Grease can create a bond between two components (sensor housing and sensor cover) and block the rotation of the sensor housing. If the temperature of the grease is risen to a predetermined level, for example a temperature at which grease can melt, the grease can get softer. When grease melts or softens the actuator, for example as linear drive, can become again able to move the rotation components (mechanism) and so turn the sensor housing and bring the sensor housing and the sensing element to the sensing (open) position.

[0049] This action can be repeated after or before or before and after every cooking cycle which was heating up the cooking compartment above 100°C, for example or another predefined temperature, for example 80° C, 90 °C or between.

[0050] By using the sensor device and the method a measuring of different levels of air humidity becomes possible with the help of the heater in the sensing element.

[0051] When the humidity level inside the cooking compartment cavity, for example after being stable for predetermined time on the 100 % rH, drops below, for example to 70 % rH, condensate can occur on the sensing surface. This can cause a constant signal reading of 100 % rH, which is not accurate since it should for this case read 70 % rH. In that case condensate on the surface should be evaporated to remove signal disturbances. This can be done with the help of the heater which works for a predetermined time and evaporates the condensate on the sensing printing (and between). After the condensate is evaporated the heater can become inactive and an accurate sensor measurement of air humidity (reading) can start.

[0052] The method can also contain a step of calibration of the sensor device.

[0053] Since the manufacturing process of the sensing element can be inconsistent, sensor's preliminary values and parameters can be different.

[0054] For the optional calibration process, first, the cooking compartment can be closed and heated up to the predefined temperature. After the sensor's reading becomes stable this point is marked as the lower measurement point.

[0055] Second, 100 % rH is detected in a way that a steam generator works for the predetermined time for which it is known that after which the cooking compartment is fully saturated. When sensor's reading becomes stable this point is marked as an upper measurement point.

[0056] Then, an extrapolation is provided to define other needed points between lower and upper measurement point. In that way, other humidity levels can be detected during sensor's function.

[0057] The cooking appliance and / or the method can be characterized by the correspondingly same features and their advantages as already mentioned in relation with the sensor device and vice versa.

[0058] BRIEF DESCIRPTION OF THE DRAWINGS

[0059] The invention will be explained in greater detail with reference to exemplary embodiments depicted in the drawings as appended. The accompanying drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification. The drawings illustrate a comparative embodiment and embodiments of the present invention and together with the description serve to explain the principles of the invention. Other embodiments of the present invention and many of the intended advantages of the present invention will be readily appreciated as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts.

[0060] Fig. 1a shows a sensor device for measuring air humidity according to an embodiment of the invention.

[0061] Fig. 1 b shows the sensor device from Fig. 1 a from an opposite view.

[0062] Fig. 2a and Fig. 2b show the sensor device from Fig. 1 a and Fig. 1 b in similar views as Fig. 1 a and Fig. 1 b, wherein Fig. 2a shows the sensor housing at another rotating position and Fig. 2b shows a opening of the sensor cover as further detail.

[0063] Fig. 3a and Fig. 3b show the sensor device from Fig. 1 a and Fig. 1 b in plan views from the rear side in two different rotation positions of the sensor housing.

[0064] Fig. 4a and Fig. 4b show the sensor cover and the sensor housing in two different rotation positions of the sensor housing according to an embodiment of the invention.

[0065] Fig. 5a - 5c shown the sensor housing in different views according to an embodiment of the invention.

[0066] Fig. 6a and Fig. 6b show a top and bottom view of the sensing element.

[0067] Fig. 7 shows a view from the interior of the cooking compartment in a cooking appliance according to an embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0068] Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. Generally, this application is intended to cover any adaptations or variations of the specific embodiments discussed herein.

[0069] Fig. 1a shows a sensor device for measuring air humidity according to an embodiment of the invention.

[0070] The sensor device 100 is shown without a wall of the cooking appliance to which it can be mounted and from a perspective direction as seen from a side which can face the interior of the cooking compartment.

[0071] The sensor device 100 for measuring air humidity inside a cooking compartment of a cooking appliance comprises a humidity sensor 1 having a sensor housing 5 and a sensing element enclosed inside the sensor housing 5. Further, having a sensor holding part 4 having a holding structure 4a which can be arranged at a wall of the cooking appliance and outside the cooking compartment and further having a sensor cover 3 which extends into the interior of the cooking compartment when the holding structure 4a is arranged outside the wall.

[0072] The sensor housing 5 can have a cylindrical shape, similar as the sensor cover 3, which is placed inside the sensor cover 3 in a rotatable manner such that the sensor housing can be rotated between a sensing position and a closed position.

[0073] The sensor device 100 further has a sensor rotating part 2 having an actuator 11 mounted or attached thereto and a rotating arm 10 which can movably extend through the supporting structure 2a to which the actuator 11 is mounted or attached, wherein the supporting structure 2a can be arranged at a wall (not shown) of the cooking appliance and outside the cooking compartment and in a vicinity of the sensor holding part 4, for example leaned or even fixed to the holding structure 4a. Therefore, the supporting structure 2a and the holding structure 4a can represent one device structure which can be rigidly connected and mounted to a wall.

[0074] The sensor device 100 can further comprise a temperature sensor 14, for example in shape of a bar, which can be arranged at the holding structure 4a and outside the cooking compartment such that the temperature sensor 14 can extend into the interior of the cooking compartment through an opening in the wall (not shown) and can extend also through the holding structure 4a at a predefined distance to the sensor cover 3, for example 1 - 5 cm away from the sensor cover 3.

[0075] A cable and / or electric contact EL from the sensing element (not shown) in the sensor housing 5 can be connected to a controller SE of the household appliance. Also the actuator 11, the temperature sensor 14 and other components can be connected to said controller SE by a cable EL.

[0076] Both the holding structure 4a and the supporting structure 2a can have regions, for example flange parts at their edges, where they can be mounted (for example screwed) to the corresponding wall of the cooking compartment and to each other. The supporting structure 2a can at least partly surround the actuator 11 and the remaining components attached at the supporting structure 2a.

[0077] Fig. 1 b shows the sensor device from Fig. 1 a from an opposite view.

[0078] In Fig. 1 b the view from the side facing away from the interior of the cooking compartment is shown and the screws SC are visible by which the flange regions FR of the holding structure 4a and the supporting structure 2a are mounted to the wall SW of the cooking compartment CD of a cooking appliance CA and to each other.

[0079] As also shown in Fig. 1 a, it is visible in Fig. 1 b from the rear side that both the holding structure 4a and the supporting structure 2a of the sensor device 100 can have regions, for example flange parts FR at their edges, where they can be mounted (for example screwed by screws SC) to the corresponding wall SW of the cooking compartment CD and to each other. The actuator 11 can be fixedly mounted to the supporting structure 2a providing a linear force in one direction (one dimension) thereby pushing and / or pulling the rotation arm 10 in said direction. At an end which is next to the sensor housing 5 the rotation arm 10 can have a slot SL, for example in vertical (perpendicular to direction of the force from the actuator 11) extent, inside which slot SL a pin P of a handle 9 of the sensor housing 5 can move thereby translating a linear force component from moving the rotation arm 10 along the linear direction into rotation of the handle 9 and of the sensor housing 5 around a symmetry axis of the sensor housing 5, which extends perpendicular to the direction of the linear force. The sensor rotating part can comprise a return spring (not shown) which can be linked to the rotating arm 10 (for example to its end opposite to said end which faces the handle 9) and to the supporting structure 2a such that the return spring pulls the rotating arm 10 against the linear direction of the force provided by the actuator 11 (for pulling the rotation arm back to an initial position). The return spring can also be omitted if the actuator can pull back the arm 10 itself. In Fig. 1 b the temperature sensor 14 and the cable connections of the temperature sensor 14 and of the sensor housing 5 are shown from the rear side. Further, a switch-element ST can be mounted at the supporting structure 2a having a contact element which can recognise protrusions of the rotation arm 10 and thereby recognize whether the rotation arm 10 (and correspondingly also the sensor housing 5 by the corresponding position of rotation) is / are in a closed or sensing position. Said switch-element ST can be connected to the controller (not shown).

[0080] The shown way of attachment can lead to an easier assembly in the production where a whole sensor assembly can represent the sensor holding part 4 and the sensor rotating part 2 as preassembled on the assembly line. Only one person is needed to position the assembly from the back side and fix it with to the wall SW, for example with the screws SC.

[0081] The majority of the components and the whole rotation mechanism can be placed on the rear wall and not inside the cooking compartment where temperatures are significantly higher. Therefore, all critical components (especially the actuator) can be placed in the area of significantly lower temperatures comparing it to the cooking compartment. This reduces components costs and prolongs product's life. When active, the (linear) actuator 11 can keep the sensor housing 5 at then opened position. Closing can be carried out together with the spring (as shown in Fig. 2a or Fig. 2b but not shown in Fig. 1 a and Fig. 1 b) which can help returning the rotation arm 10 to the initial position (closed). During closing, the actuator 11 can be inactive. This action is repeated for any opening or closing process.

[0082] Fig. 2a and Fig. 2b show the sensor device from Fig. 1 a and Fig. 1 b in similar views as Fig. 1 a and Fig. 1 b, wherein Fig. 2a shows the sensor housing at another rotating position and Fig. 2b shows a opening 3a of the sensor cover 3 as further detail such that Fig. 2a shows the rotation arm 10 being pushed to the maximum right position and to maximum rotation position in clockwise when seen from rear side which can, for example, correspond to the closed position since at the left end of the rotation arm 10 (opposite to the end which faces the sensor housing) the vertical component VC of the rotation arm 10 can touch the actuator 11 already and the return spring 15 can be in minimum extension. The vertical component VC of the rotation arm 10 can at its lower part be connected to the actuator 11 and at its upper part be connected to the return spring 15.

[0083] In Fig. 2b the view from the interior of the cooking compartment is shown on the sensor cover 3 and on the sensor housing 5. The sensor cover 3 can have a sensor opening 3a to expose the sensing element in the sensor housing 5 to the interior of the cooking compartment. In Fig. 2b the sensor housing 5 can be seen through the sensor opening 3a but showing no opening in the sensor housing since the sensor housing 5 is rotated in Fig. 2b to a closed position. Both the sensor opening 3a and the opening in the sensor housing 5 can be directed perpendicular to the symmetry axis of the sensor cover 3 and the sensor housing 5.

[0084] During a cooking process, grease and oils can pile up on both the sensor housing 5 and the sensor cover 3. On the lower temperatures grease can help the movement since it lubricates both components. However, during pyrolytic cycle, grease and oils can get burned which can cause a mechanism blockage (linear drive not powerful enough to open the mechanism). This problem can be solved with the help of two effects. First, the holder of the sensor housing and the rotation arm 10 can be is offset from the sensors axis centre which helps creating a momentum during movement. In that way, the force of the (linear) actuator 11 can be increased for a little. Secondly, a heater on the sensing element can be activated to soften the grease. Once the heater heats up the sensor housing 5 it can melt grease on the surface. This cause easier opening of the mechanism, and lower forces needed to overcome by the actuator 11.

[0085] Fig. 3a and Fig. 3b show the sensor device 100 from Fig. 1 a and Fig. 1 b in plan views from the rear side in two different rotation positions of the sensor housing 5.

[0086] The rear side is said side which faces away from the interior of the cooking compartment. In other words, a direction into the plane of the Figures is a direction into the interior of the cooking compartment.

[0087] In Fig. 3a a first position of the sensor housing 5 is shown, for example a sensing and open position. In this case the rotation arm 10 is pushed by the actuator 11 in its linear direction of force to the maximum linear amplitude of the actuator 11, which can in this example be away from the sensor housing 5 (other configurations may provide the actuator 11 such that it pushes the rotation arm 10 towards the sensor housing 5). In this position the rotation arm 10 pulls the return spring 15 to its stretched position. The pin P of the handle 9 is in the lowest position of the slot SL of the rotation arm 10 and in maximum left position when seen from rear view.

[0088] In Fig. 3b a second position of the sensor housing 5 is shown, for example a closed position. In this case the rotation arm 10 is pulled by the actuator 11 in its linear direction of force to the minimum linear amplitude of the actuator 11. In this position the rotation arm 10 is pulled by the return spring 15 to lower its stretching. The pin P of the handle 9 is in the lowest position of the slot SL of the rotation arm 10 again but now in maximum right position when seen from rear view and in clockwise direction of rotating the sensor housing 5. During rotation between these two maximum positions the pin P can move up inside the slot SL for translation of linear force to rotation. Due to said rotation the method according to the invention may be performed, for example on such a sensor device, wherein determining S1 a prevailing condition inside the cooking compartment whether to measure the air humidity at a particular time or time-period inside the cooking compartment by a humidity sensor which has a sensing element that can be exposed to the air inside the cooking compartment, wherein the prevailing condition is measured by a temperature sensor inside the cooking compartment and / or evaluated by a user or by a cooking programme. Further, corresponding positions for sensing or closing the sensor housing can be reached with measuring or not can be performed.

[0089] Fig. 4a and Fig. 4b show the sensor cover and the sensor housing in two different rotation positions of the sensor housing according to an embodiment of the invention.

[0090] In Fig. 4a and Fig. 4b the sensor cover 3 is shown in a perspective view and without the rest of the sensor holding part. Fig. 4a shows the sensing position (open position) where a sensor opening 3a of the sensor cover 3 can be a cut-out from a front end (the front end facing towards the interior of the cooking compartment) and having also a lateral cut-out part perpendicular to the symmetry axis of the sensor cover 3. Further, the sensor housing 5 is placed inside the sensor cover 3 in a rotatable manner such that the sensor housing 5 can be rotated to the sensing position and to a closed position as shown in Fig. 4b such that the opening 5a of the sensor housing at least partly overlaps with the sensor opening 3a as shown in Fig. 4a to expose the sensing element (not shown) to the interior of the cooking compartment in the sensing position and that the opening 5a is fully covered by the sensor cover 3 to cover the sensing element towards the interior of the cooking compartment when in the closed position as shown in Fig. 4b. Further, it is shown that the handle 9 has a different position of rotation when seen in Fig. 4a and Fig. 4b.

[0091] Fig. 5a - 5c shown the sensor housing 5 in different views according to an embodiment of the invention.

[0092] In Fig. 5a the cylindrical shape of the sensor housing 5 is shown having a cap region 6 at its end which faces away from the handle 9. The handle 9 can be rigidly connected to the cylin- dric part and can have a pin P at its rear end (first end E1) with an electric cable EL stretching through the handle 9. The opening 5a in the sensor housing 5 can be located at a region close to the cap 6, for example 1 cm next to and consist of a lateral cut-out in the sensor housing 5.

[0093] Fig. 5a showns a lateral side view wherein Fig. 5b shows a top view from which the interior of the opening 5a with the sensing element 7 inside the opening 5a can be seen.

[0094] Fig. 5c shows a longitudinal cut through the sensor housing 5 wherein it can be seen that the cap 6 is stacked into the sensor housing 5 from front side and that the sensing element 7 can be embedded (or just fixedly arranged inside) the sensor housing 5 (such that it does not move inside the sensor housing during rotation of the sensor housing 5). Further, there can be an embedding material 8 filling the rest of the interior of the sensor housing 5 and fixing the cable EL and the rear opening of the sensor housing 5 and seal its interior.

[0095] The sensor housing 5 can comprise or consist of a cylindric metal (stainless steel or brass) in which the sensing element 7 is placed.

[0096] In other words, the sensing element 7 can be placed inside the sensor housing 5 and fixed with a sealing material 8. The sealing material can be any material that is not porous and can withstand high temperatures, for example glass. The sensing element 7 can be positioned such that the sensing printing (for example a metaloxide) can always face the side where the opening 5a is located. Therefore, whenever the mechanism rotates the sensor housing 5 to the sensing position the sensing element 7 can be directly facing humid air coming our from the oven's fan cover.

[0097] The cap 6 can be a metal cap. The cable EL can be sealed with a high temperature fibre glass material which can protect the cables even during pyrolyze.

[0098] Fig. 6a and Fig. 6b show a top and bottom view of the sensing element 7. The sensing element 7 can have a sensing side 7a, for example a top side which can be exposed through the opening in the sensor housing and which is shown in Fig. 6a, and a heating side 7b which is shown in Fig. 6b and which can be opposite the sensing side 7a and wherein the sensing side 7a can comprises a substrate S and a sensing printing B on the substrate S and the sensing printing B having a changing resistivity when contacting humid air and the heating side 7b can comprise a heating element H (heater) for heating the sensor housing and the sensing element 7 and wherein the sensing element 7 can further comprise a temperature sensing part T (also as printing on the substrate S or next to it), which can be embedded in the substrate S or placed on the sensing side 7a and between or adjacent to the sensing printing B. The heater H as printing itself can extend below and along the region where the sensing printing 7a is above.

[0099] The sensing element 7 can be made of the ceramic substrate S with a sensing printing B on the top side (sensing side 7a). As already mentioned, when humid air comes in the contact with the sensing printing it can makes a light contact which results in change of the resistance.

[0100] With the heater H it can be achieved that it evaporates any condensate on the surface of the sensing element 7 which can effect the measurement signal. Second, it can heat up the whole housing (sensor housing and sensor cover) and soften grease which can be accumulated during cooking between the sensor housing and the sensor cover and can in that way help to movement of the sensor housing and of the rotation mechanism. It also prevents blockage of the mechanism.

[0101] The ceramic substrate S can be fully exposed in the area where the sensing printing is located (Fig. 6a). However, on the remaining part, for example above the temperature sensing part or at electric contacts the sensing element 7 can be embedded by another material.

[0102] Fig. 7 shows a view from the interior of the cooking compartment CD in a cooking appliance CA according to an embodiment of the invention. In Fig. 7 the rear side SW of the cooking compartment CD is shown having a fan F with a fan cover FC which can be mounted at the rear wall SW with holes in the fan cover FC in a middle region and the zoomed view shows the ventilation holes VH with the temperature sensor 14 and the sensor cover 3 with the sensor housing 5 inside located next to the ventilation holes VH (and extending through an edge of the fan cover FC). The sensor opening can be oriented towards the ventilation holes VH.

[0103] The wall SW can be a rear wall of the cooking compartment and wherein a fan F with a fan elise is located at the rear wall SW and a fan cover FC with an opening or holes in its central region for the fan F can be attached to the rear wall SW such that the fan elise is located between the rear wall SW and the fan cover FC for sucking air from the interior of the cooking compartment and wherein the fan cover FC has ventilation holes VH at edge regions of the fan cover FC through which ventilation holes VH a part of the humid air from the fan F enters again the interior of the cooking compartment and wherein the opening in the rear wall SW through which the sensor cover and the sensor housing extend into the interior of the cooking compartment is located adjacent to at least one of the ventilation holes VH and wherein the sensor opening is directed towards the at least one of the ventilation holes VH. The fan cover FC can have an elevated inner part which can have a difference in height relative to the edge regions where the opening for the sensor cover is. The ventilation holes VH can be located at sidewalls of this elevated part and directed towards the edge regions and to the sensor cover.

[0104] Therefore, the sensing part of the humidity sensor can thus be placed inside the cooking compartment CD and next to the rear wall, which can in this region also represent the oven fan cover. Such a placement of the sensor directly in the cooking compartment can enable accurate measurement of the conditions inside the cavity and improve the measurement.

[0105] In the foregoing detailed description, various features are grouped together in one or more examples or examples with the purpose of streamlining the disclosure. It is to be understood that the above description is intended to be illustrative, and not restrictive. It is intended to cover all alternatives, modifications and equivalents.

Claims

CLAIMS1 . Sensor device (100) for measuring air humidity inside a cooking compartment (CD) of a cooking appliance (CA), comprising:- a humidity sensor (1) having a sensor housing (5) and a sensing element (7) enclosed inside the sensor housing (5), wherein the sensor housing (5) has an opening (5a) at a region where the sensing element (7) is positioned such that a sensing side (7a) of the sensing element (7) is exposed through the opening (5a);- a sensor holding part (4) having a holding structure (4a) which can be arranged at a wall (SW) of the cooking appliance (CA) and outside the cooking compartment (CD) and further having a sensor cover (3) which extends into the interior of the cooking compartment (CD) through an opening in the wall (SW) when the holding structure (4a) is arranged outside the wall (SW) and the sensor cover (3) further having a sensor opening (3a), and wherein the sensor housing (5) is placed inside the sensor cover (3) in a rotatable manner such that the sensor housing can be rotated between a sensing position and a closed position such that the opening (5a) at least partly overlaps with the sensor opening (3a) to expose the sensing element (7) to the interior of the cooking compartment (CD) in the sensing position and that the opening (5a) is fully covered by the sensor cover (3) to cover the sensing element (7) towards the interior of the cooking compartment (CD) when in the closed position; and- a sensor rotating part (2) having an actuator (11) and a rotating arm (10) and a supporting structure (2a) to which the actuator (11) is mounted, wherein the supporting structure (2a) can be arranged at a wall (SW) of the cooking appliance (CA) and outside the cooking compartment (CD) and in a vicinity of the sensor holding part (4) such that the rotating arm (10) is linked both to the actuator (11) and to the humidity sensor (1) for rotating the sensor housing (5) between the sensing position and the closed position by the actuator (11) over the rotating arm (10).

2. Sensor device (100) according to claim 1, further comprising a temperature sensor (14) which is arranged at the holding structure (4a) and / or at a wall (SW) of the cooking appliance (CA) and outside the cooking compartment (CD) such that the temperature sensor(14) can extend into the interior of the cooking compartment (CD) through an opening in the wall (SW).

3. Sensor device (100) according to claim 1 or 2, wherein the sensor housing (5) and the sensor cover (3) have at least partly a cylindrical shape and extend coaxially and the sensor housing (5) is rotatable around the cylindrical axis.

4. Sensor device (100) according to any of claims 1 to 3, wherein the humidity sensor (1) has a handle (9) at a first end (El ) of the sensor housing (5) facing away from the sensor cover (3) and being linked to the rotating arm (10), wherein a cable and / or electric contact (EL) is connected to the humidity sensor (1) through the first end (E1).

5. Sensor device (100) according to any of claims 1 to 4, wherein the sensing element (7) has a sensing side (7a) and a heating side (7b) which is opposite the sensing side (7a) and wherein the sensing side (7a) comprises a substrate (S) and a sensing printing (B) on the substrate (S) and the sensing printing (B) having a changing resistivity when contacting humid air and the heating side (7b) comprises a heating element (H) for heating the sensor housing (5) and the sensing element (7) and wherein the sensing element (7) further comprises a temperature sensing part (T), which is embedded in the substrate (S) or placed on the sensing side (7a) and between or adjacent to the sensing printing (B).

6. Sensor device (100) according to any of claims 1 to 5, wherein the actuator (11) is a waxmotor for providing a linear force to the rotating arm (10) for providing a translatoric force to or away from the humidity sensor (1) from a direction perpendicular to a longitudinal extent of the sensor housing (5) to a rotational force component for rotation of the sensor housing (5) around its longitudinal axis.

7. Sensor device (100) according to any of claims 1 to 6, wherein the sensor rotating part (2) comprises a return spring (15) which is linked to the rotating arm (10) and to the supporting structure (2a) such that the return spring (15) pulls the rotating arm (10) against a linear direction of the force provided by the actuator (11).

8. Sensor device (100) according to any of claims 1 to 7, wherein the sensor rotating part (2) is connected to the sensor holding part (4).

9. Cooking appliance (CA) comprising:- a cooking compartment (CD) with walls (SW);- a sensor device (100) according to any of claims 1 to 8, which is mounted at a wall (SW) of the cooking compartment (CD) such that the sensor holding part (4) with the holding structure (4a) is arranged at the wall (SW) of the cooking appliance (CA) and outside the cooking compartment (CD) and further the sensor cover (3) extends into the interior of the cooking compartment (CD) through an opening in the wall (SW) when the holding structure (4a) is arranged outside the wall (SW) wherein the sensor housing (5) is placed inside the sensor cover (3) in a rotatable manner and extends with the sensor cover (3) into the interior of the cooking compartment (CD) and the sensor rotating part (2) having the actuator (11) and the rotating arm (10) and the supporting structure (2a) to which the actuator (11) is mounted and wherein the supporting structure (2a) is arranged at the wall (SW) of the cooking appliance (CA) and outside the cooking compartment (CD); and- a controller (SE), which is connected to the sensing element (7) and to the actuator (11) and which is configured to sense a relative and / or absolute humidity of the air in the cooking compartment (CD) from a change in resistance at the sensing element (7) and to provide a force from the actuator (11) to the rotating arm (10) thereby rotating the sensor housing (5) between a sensing position and a closed position such that the opening (5a) at least partly overlaps with the sensor opening (3a) to expose the sensing element (7) to the interior of the cooking compartment (CD) in the sensing position and that the opening (5a) is fully covered by the sensor cover (3) to cover the sensing element (7) towards the interior of the cooking compartment (CD) when in the closed position.

10. Cooking appliance (CA) according to claim 9, wherein the cooking appliance is a built-in oven or a standalone oven with steam function and / or with pyrolytic function and / or a microwave.1 1 . Cooking appliance (CA) according to claim 9 or 10, wherein the controller (SE) is further configured to operate the heating element (H) such to heat the sensing side (7a) and lower or evaporate a condensate from the humid air on the sensing printing (B) and / or such that the sensor housing (5) and / or the sensor cover (3) are heated up to soften grease between the sensor housing (5) and the sensor cover (3) such to keep the sensor housing (5) rotatable against grease between the sensor housing (5) and the sensor cover (3).

12. Cooking appliance (CA) according to any of claims 9 to 11, wherein the wall (SW) is a rear wall of the cooking compartment (CD) and wherein a fan (F) with a fan elise is located at the rear wall (SW) and a fan cover (FC) with an opening or holes in its central region for the fan (F) is attached to the rear wall (SW) such that the fan elise is located between the rear wall (SW) and the fan cover (FC) for sucking air from the interior of the cooking compartment (CD) and wherein the fan cover (FC) has ventilation holes (VH) at edge regions of the fan cover (FC) through which ventilation holes (VH) a part of the humid air from the fan (F) enters again the interior of the cooking compartment (CD) and wherein the opening in the rear wall (SW) through which the sensor cover (3) and the sensor housing (5) extend into the interior of the cooking compartment (CD) is located adjacent to at least one of the ventilation holes (VH) and wherein the sensor opening (3a) is directed towards the at least one of the ventilation holes (VH).

13. Cooking appliance (CA) according to any of claims 9 to 12, wherein the controller (SE) is further configured to adjust a steam function and thereby a value of relative or absolute humidity in the interior of the cooking compartment (CD) due to a measured relative or absolute air humidity at the sensing element (7) and due to a cooking programme.

14. Method for measuring of air humidity inside a cooking compartment (CD) of a cooking appliance (CA), comprising the steps:- determining (S1) a prevailing condition inside the cooking compartment (CD) whether to measure the air humidity at a particular time or time-period inside the cooking compartment (CD) by a humidity sensor (1) which has a sensing element (7) that can be exposed to the air inside the cooking compartment (CD), wherein the prevailing condition ismeasured by a temperature sensor (14) inside the cooking compartment (CD) and / or evaluated by a user or by a cooking programme;- keeping a sensor housing (5) of the humidity sensor (1) in a sensing position or rotating the sensor housing (5) to a sensing position and measuring relative and / or absolute humidity of the air in the cooking compartment by a sensing element (7) of the humidity sensor (1) if the prevailing condition inside the cooking compartment (CD) is determined as suitable for measuring air humidity inside the cooking compartment (CD) and / or keeping the sensor housing (5) in a closed position or rotating the sensor housing (5) to the closed position if the prevailing condition inside the cooking compartment (CD) is determined as not being suitable for measuring air humidity inside the cooking compartment (CD), wherein the rotating is performed by a mechanism which is placed outside the cooking compartment (CD).

15. Method according to claim 14, wherein the sensor housing (5) is placed inside the sensor cover (3) in a rotatable manner such that the sensor housing can be rotated between the sensing position and the closed position such that an opening (5a) of the sensor housing (5) at least partly overlaps with the sensor opening (3a) of a sensor cover (3) to expose the sensing element (7) placed inside the sensor housing (5) to the interior of the cooking compartment (CD) in the sensing position and that the opening (5a) is fully covered by the sensor cover (3) to cover the sensing element (7) towards the interior of the cooking compartment (CD) when in the closed position, wherein the sensor cover (3) extends into the cooking compartment (CD) and the sensor housing (5) is placed inside the sensor cover (3).

16. Method according to claim 14 or 15, wherein the prevailing condition is suitable for measuring air humidity inside the cooking compartment (CD) if a temperature of air inside the cooking compartment (CD) is lower or equal to 100 ° C and / or if a cooking programme with a low greasy aerosol level and / or if steam cooking is chosen.

17. Method according to any of claims 14 to 16, wherein the prevailing condition is not suitable for measuring air humidity inside the cooking compartment (CD) if a temperature ofair inside the cooking compartment (CD) is higher than 100 ° C and / or if a cooking programme with a high greasy aerosol level is chosen and / or if a pyrolytic cycle is chosen.

18. Method according to any of claims 14 to 17, wherein the sensing element (7) has a sensing side (7a) and a heating side (7b) which is opposite the sensing side (7a) and wherein the sensing side (7a) comprises a substrate (S) and a sensing printing (B) on the substrate (S) and the sensing printing (B) having a changing resistivity when contacting humid air and the heating side (7b) comprises a heating element (H) for heating the sensor housing (5) and the sensing element (7) and wherein the sensing element (7) further comprises a temperature sensing part (T), which is embedded in the substrate (S) or placed on the sensing side (7a) and between or adjacent to the sensing printing (B) and the heating element (H) is operated such to heat the sensing side (7a) above a predetermined temperature which is monitored by the temperature sensing part (T) and lower or evaporate a condensate from the humid air on the sensing printing (B) and / or such that the sensor housing (5) and / or the sensor cover (3) are heated up to a grease softening temperature which is monitored by the temperature sensing part (T) to soften grease between the sensor housing (5) and the sensor cover (3) such to keep the sensor housing (5) rotatable against grease between the sensor housing (5) and the sensor cover (3).

19. Method according to any of claims 14 to 18, which is performed on a cooking appliance according to any of claims 9 to 13.

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