Cooking appliance having an antenna arranged outside the cooking chamber

Abstract

The invention relates to a cooking appliance (1), having a closable cooking chamber (2) with at least one leakage path (LP), arranged between the cooking chamber (2) and its outer surroundings, for electromagnetic waves, and a free-standing antenna (13), arranged in outer surroundings of the cooking chamber (2), for data signals transferred via the at least one leakage path (LP), said antenna being connected to a transmission and / or receiving circuit (15) for the data signals. The invention also relates to a system having the cooking appliance (1) and a functional unit (3) which is to be arranged in the cooking chamber (2) and which is equipped with a wireless transmission and / or receiving device (12) for the data signals, wherein when the cooking chamber (2) is closed, data signals can be transferred between said transmission and / or receiving device (12) and the transmission and / or receiving circuit (15) of the cooking appliance (1) via at least one leakage path (LP). The invention also relates to a corresponding method. The invention is particularly advantageously applicable to ovens having a microwave function.

Description

[0001] Cooking appliance with antenna located outside the cooking chamber

[0002] The invention relates to a cooking appliance comprising a closable cooking chamber with at least one path for electromagnetic waves between the cooking chamber and its external environment, and an antenna for transmitted data signals arranged in an external environment of the cooking chamber, which antenna is connected to a transmitting and / or receiving circuit for the data signals. The invention also relates to a system comprising such a cooking appliance and a functional unit to be arranged in the cooking chamber, which is equipped with a wireless transmitting and / or receiving device for the data signals. The invention further relates to a method in which data signals are transmitted between a functional unit arranged in a closed cooking chamber of a cooking appliance and a transmitting and / or receiving circuit arranged in an external environment of the cooking chamber.The invention is particularly advantageously applicable to ovens with, but also without, microwave function.

[0003] DE 10 2009 027 920 A1 discloses a cooking appliance comprising a cooking chamber, a cooking chamber, and a fan for blowing air into the cooking chamber. An electrical control unit is arranged in the cooking appliance and is electrically connected to an antenna. The antenna is intended for signal transmission to a measuring device located in the cooking chamber and is a component of the fan.

[0004] DE 10 2013 114 066 A1 describes a fan wheel for a cooking appliance, comprising a shaft connectable to a drive unit for rotating the fan wheel and a source of electromagnetic waves and / or a receiving unit for electromagnetic waves, at least one waveguide for electromagnetic waves, and at least one antenna connected to the at least one waveguide. The invention also relates to a cooking appliance with at least one such fan wheel and a cooking method for such a cooking appliance.

[0005] EP 0 459 305 B1 discloses a high-frequency heating device with a high-frequency oscillator for generating high-frequency oscillations from electrical energy of a power supply unit; with a housing in the shape of a rectangular parallelepiped enclosing a heating chamber into which the high-frequency oscillations of the high-frequency oscillator are introduced; with an antenna arranged outside the heating chamber and adjacent to an elongated opening in the wall of the housing; with a dielectric plate covering the opening and arranged on the wall of the housing so that the opening lies between it and the antenna; with a detector receiving the output signal of the antenna and having a grounded portion connected to the housing; and with a control circuit to which the output signal of the detector is supplied and which outputs a control signal to the power supply unit.wherein the housing has the contour of a straight wall section in a plane in which the opening is opposite the dielectric plate, and the elongated opening runs with its longitudinal direction obliquely to the straight wall section of the contour;

[0006] EP 3 188 571 B1 discloses a cooking appliance comprising: a housing enclosing an interior space, wherein at least a portion of the housing comprises an electrically conductive portion; and an antenna for at least one of receiving radio frequency signals and transmitting radio frequency signals, wherein the antenna comprises an active component and a connection to the electrically conductive portion such that the electrically conductive portion serves as a ground plane of the antenna, wherein the housing further comprises a door assembly having a closed position and an open position to allow a user access to the interior space, wherein the door assembly includes a window to allow viewing of the interior space from outside the interior space, wherein the window encloses the electrically conductive portion in the form of at least one transparent conductive layer.

[0007] EP 3 443 267 B1 discloses a cooking appliance with a cooking chamber for cooking food, with an air baffle arranged in the cooking chamber, a transmitting / receiving unit for transmitting and / or receiving a high-frequency signal, and a coupling device for coupling the transmitting / receiving unit and the air baffle, wherein the air baffle is designed as a surface antenna for transmitting the high-frequency signal between the coupling device and a sensor that can be arranged in the cooking chamber, wherein the coupling device comprises a spiral electrical line for capacitive coupling with the air baffle for transmitting the high-frequency signal.WO 2006 / 111226 A1 discloses a household appliance, in particular a cooking appliance, having an interior defined by a housing and a door, an electrical control system, and a measuring device for measuring a physical quantity, in particular temperature. The measuring device comprises a probe antenna arranged on the measuring probe and a transmitting or receiving antenna connected to the electrical control system for wireless signal transmission between a measuring probe arranged in the interior and the electrical control system. The transmitting or receiving antenna is arranged on the housing and is essentially hermetically sealed from the interior by a cover permeable to electromagnetic radiation. In order to provide a household appliance with reduced manufacturing complexity and thus reduced costs, the transmitting or receiving antenna is a component of a lighting device for illuminating the interior.

[0008] DE 10 2007 043 370 B3 discloses a household appliance with a treatment chamber, an electrical control system and a rod antenna having an elongated base body which is delimited in the longitudinal direction by two front ends, wherein the rod antenna is held in the treatment chamber on a wall of the treatment chamber and by means of which electrical signals are transmitted wirelessly between a transmitting or receiving device arranged in the treatment chamber and the electrical control system.

[0009] DE 10 2011 109 163 A1 discloses a furnace with a heating element arranged in a treatment chamber of the furnace, comprising a metallic outer shell and a retaining flange, wherein the heating element is attached to the retaining flange via the metallic outer shell, and an interrogation antenna of a wireless measuring system for monitoring furnace material. According to the invention, the interrogation antenna of the wireless measuring system is formed by the heating element in the treatment chamber of the furnace, in that the metallic outer shell of the heating element is insulated from the retaining flange at least at one connection end.

[0010] EP 2 662 629 A1 discloses a household appliance with a treatment chamber to which an antenna is assigned. A coupling arrangement is provided in the treatment chamber, which is operatively connected to the antenna via a connecting device. EP 2 663 160 A1 discloses a household appliance with a treatment chamber and with a coupling device for transmitting electromagnetic radiation into the treatment chamber. The coupling device is arranged in an adjacent chamber. The adjacent chamber is separated from the treatment chamber by at least one partition wall. The coupling device is designed to generate an electromagnetic field between a first metallic wall and an adjacent second metallic wall. At least one opening is provided, via which at least the electromagnetic radiation is transmitted into the treatment chamber.

[0011] DE 10 2012 221 015 A1 discloses a cooking appliance, in particular an oven, comprising a cooking chamber with cooking chamber walls and a fan opening into the cooking chamber. This fan opening is provided on a fan plate mounted in front of a cooking chamber wall, wherein an antenna for wireless signal transmission is provided with a measuring device located in the cooking chamber with a transmitting and receiving antenna. The antenna is arranged between the fan plate and the cooking chamber wall and is thus covered or protected from the inside.

[0012] EP 2 741 009 A1 discloses a heating and signal receiving arrangement for a cooking appliance with a cooking chamber, which can be arranged in the cooking chamber and comprises a heating element and a signal receiving element. The signal receiving element is configured as a slot antenna that is thermally connected directly to the heating element. A cooking appliance with such a heating and signal receiving arrangement is also disclosed.

[0013] EP 3 121 573 A1 discloses an oven, in particular an oven or microwave oven, comprising an oven muffle for actively temperature-treating a substance and for receiving the substance via a chamber opening, a door configured to open and close the chamber opening in a first and second position, respectively, and at least one receiving or transmitting / receiving element enabling at least unidirectional wireless communication of signals from and / or to at least one sensor unit placed on or in the oven muffle, wherein: the at least one receiving or transmitting / receiving element is positioned within a space between two walls and / or panes of the door. WO 2021 / 239233 A1 discloses a microwave oven, a sensor arrangement, a system comprising a microwave oven and a sensor arrangement, and a corresponding method for controlling a microwave oven.The method comprises: measuring the temperature; providing first data; accessing second data; providing control data; communicating sensor array data comprising the control data or comprising the first and second data; and controlling the microwave oven in dependence on the control data.

[0014] WO 2022 / 008050 A1 discloses a sensor arrangement and a receiver arrangement for a microwave oven. The sensor arrangement can harvest energy from the microwave radiation and generate a modulated backscatter signal of a higher harmonic. The receiver arrangement can receive and extract the modulated backscatter signal from the intense background microwave radiation.

[0015] It is the object of the present invention to at least partially overcome the disadvantages of the prior art and in particular to provide a particularly simple and cost-effective way of transmitting data signals from a closed cooking chamber to the outside and / or introducing them from the outside into the closed cooking chamber.

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

[0017] The task is solved by a cooking appliance comprising

[0018] - a closable cooking chamber with at least one leakage path for electromagnetic waves between the cooking chamber and its external environment and

[0019] - a free-standing antenna arranged on an external environment of the cooking chamber for data signals transmitted via the at least one leakage path,

[0020] - which is connected to a transmitting and / or receiving circuit for the data signals.

[0021] This provides the advantage that existing electromagnetic leakage paths can now also be used for signal transmission, eliminating the need for special configurations of the cooking chamber wall and / or door, e.g., through dedicated signal feedthroughs, or through antennas routed through the cooking chamber wall and / or door and specifically adapted for transmitting data signals. In particular, by eliminating dedicated penetrations in the cooking chamber wall and / or door, the associated disadvantages such as increased heat loss, increased leakage of microwave radiation, steam leakage, and / or hot air leakage, etc., can be avoided.

[0022] The cooking appliance is, in particular, a household cooking appliance. The cooking appliance may, for example, have an oven function, a microwave function, a steaming function, a vacuum function, or any combination, and may then be, for example, an oven, a microwave oven, an oven / microwave combination appliance, a steamer, a rice cooker, etc.

[0023] The cooking chamber can be closed with a door, e.g., the front door, or with a lid. When closed, the cooking chamber is not completely sealed against electromagnetic radiation, e.g., radio waves. Instead, electromagnetic radiation can penetrate the cooking chamber from the outside via leakage paths and / or escape from the cooking chamber to the outside.

[0024] A leakage path is understood in particular to be a path for electromagnetic radiation, possibly of a specific frequency band, which is not specifically intended or adapted to conduct the electromagnetic radiation. When routed via the leakage path, the electromagnetic radiation is usually attenuated. A leakage path is understood in particular not to be a signal path in which the data signals are passed through a cooking chamber boundary using an electrical conductor specifically intended or adapted for this purpose, and in particular not if this electrical conductor also performs other functions. In particular, signal paths through shafts or axles, fan wheels, lamp sockets, etc. specifically designed for data conduction are not considered leakage paths. Signal paths through openings in the cooking chamber boundary specifically designed for signal transmission are also not considered leakage paths.The antenna is sensitive to the data signals. The antenna comprises, in particular, at least one electrical conductor, e.g., a wire, a conductor track, etc. The fact that the antenna is freestanding means, in particular, that it does not contact any electrical conductor section of the leakage path, if present at all. In other words, the antenna does not contact the leakage path, e.g., not via sliding contacts, solder joints, plug connections, etc. The fact that the antenna is arranged on the outer surroundings of the cooking chamber can, in particular, mean that the antenna is arranged outside the cooking chamber delimited by the cooking chamber wall and the closed door.

[0025] The antenna can be, for example, a monopole, inverted-F, slot, coil, or loop antenna, but is not limited to these; in principle, it can have any shape. Any antenna shape can be easily achieved, particularly by printing metallic tracks onto an electrically non-conductive body.

[0026] A particularly advantageous development for achieving particularly good transmission quality is that the antenna is impedance-matched to the frequency of the data signal to be transmitted. This can be achieved by adjusting the mechanical dimensions of the antenna type used. Alternatively or additionally, impedance matching can be achieved, for example, by providing transformation lines and / or passive components, such as capacitors and inductors, for the desired transmission frequency range. The transformation line is the antenna line, the length of which is tuned according to the transmission frequency in question.

[0027] The data signals comprise, in particular, data or information transmitted by electromagnetic waves. The data signals can, for example, be imposed on an electromagnetic wave by amplitude modulation and / or angle modulation. The data signals can be digital or analog data signals. The data signals can, for example, comprise control signals, measurement signals, status signals, etc. The data signals can, in particular, be radio signals.

[0028] The fact that the antenna is connected to a transmitting and / or receiving circuit for the data signals means, in particular, that this circuit is also arranged outside the cooking chamber, which advantageously reduces thermal and other loads on the circuit.

[0029] A further development is that the antenna is connected to the transmitting and / or receiving circuit via an electrical cable ("antenna cable"). To avoid stray interference, the antenna cable is advantageously a shielded cable, e.g., a coaxial cable or a twisted-pair cable. A further development is that the antenna and the antenna cable are integrated into a single component, e.g., in the form of a shielded wire, the end region of which, facing away from the transmitting and / or receiving circuit, serves as a freestanding antenna and is stripped for this purpose. However, the antenna can also be a standalone component (e.g., an antenna module) that can be connected to the antenna cable via a cable connection. A further development is that the antenna cable is installed near large ground planes (e.g., a housing panel, an intermediate rear panel, etc.).) because this keeps impedance ratios largely constant and prevents electromagnetic interference as far as possible.

[0030] The transmitting and / or receiving circuit can be a pure transmitting circuit (transmitter), by means of which data signals can be radiated into the cooking chamber via the antenna and further via the leakage path. Alternatively, the transmitting and / or receiving circuit can be a pure receiving circuit (receiver), by means of which data signals can be received from the cooking chamber via the leakage path and further via the antenna. Furthermore, the transmitting and / or receiving circuit can be a transmitting and receiving circuit (transceiver), by means of which data signals can be received from the cooking chamber and radiated into the cooking chamber. In the transmitting and / or receiving circuit, if a device for data reception is provided, signal evaluation can take place, e.g., using analog and digital signal processing.

[0031] In a further development, the transmitting and / or receiving circuit is coupled to a data processing device of the cooking appliance, whereby the data signals can advantageously be used, for example, to monitor and control a cooking process. The transmitting and / or receiving circuit can be present as a standalone module or can be integrated into the data processing device. The data processing device can be a control device for controlling the operation of the cooking appliance.

[0032] The present method also offers the advantage that the transmitting and / or receiving circuit with antenna can be installed outside the cooking chamber without requiring any modifications to the rest of the cooking appliance in the area of ​​the leakage path. The method can therefore be implemented in conventional cooking appliances with only minimal structural modifications. The antenna can be positioned anywhere outside the oven where this is mechanically feasible and where a sufficiently strong data or communication signal is available.

[0033] It is a further development that the transmitting and / or receiving circuit is designed as an electronic assembly or electronics with at least one printed circuit board. In this case, it is a further development that the antenna is also formed on the printed circuit board, e.g., as an electrical coupling surface. The coupling surface can be created, for example, by printing, electroplating, laser treatment, etc. An antenna line can be present on the conductor surface, e.g., in the form of a conductor track; however, an antenna line can optionally be omitted. The transmitting and / or receiving circuit, the antenna, and, if present, the antenna line can, in particular, be designed as a uniformly manageable module.

[0034] In one embodiment, at least one leakage path has an electrical conductor leading through a boundary of the cooking chamber (e.g., through the cooking chamber wall and / or the door), the antenna is arranged at a distance from this electrical conductor, and the antenna is configured to exchange data signals with the electrical conductor. This provides the advantage of a particularly wear-free antenna that can be positioned easily and in a variety of ways. The electrical conductor protrudes, in particular, from the outside into the cooking chamber through an opening in the cooking chamber boundary.

[0035] The fact that the antenna is configured to exchange data signals with the electrical conductor includes, in particular, that it is configured to wirelessly tap data signals from the electrical conductor and / or feed them into the electrical conductor. Tapping from the electrical conductor takes advantage of the fact that the electrical conductor, due to the coupling of the data signals into the cooking chamber, generates an electromagnetic stray field outside the cooking chamber, which can be coupled into the antenna. Conversely, the antenna can generate a transmission field that is coupled into the electrical conductor outside the cooking chamber and generates a corresponding electromagnetic stray field inside the cooking chamber.

[0036] The antenna can be coupled to the electrical conductor, for example, inductively or capacitively. The electrical conductor can be or comprise at least one electrically conductive component leading or projecting through the boundary of the cooking chamber and optionally at least one further component electrically connected to this component outside the cooking chamber or the cooking chamber boundary. For example, both a motor shaft projecting through a cooking chamber wall and a drive motor connected to it and / or a suspension thereof outside the cooking chamber can serve as sources for generating the stray field that can be picked up by the antenna.

[0037] One embodiment involves the electrical conductor being part of a functional element that extends from the outside of the cooking chamber into the cooking chamber. This generally enables a particularly high and / or well-reproducible signal strength of the data signal.

[0038] It is a design that the functional part

[0039] - a motor shaft of a hot air engine,

[0040] - a grill heater,

[0041] - a lamp construction,

[0042] - a sensor element,

[0043] - an actuator element,

[0044] - an electrical supply line and / or

[0045] - is a fastening element.

[0046] In one embodiment, at least one leakage path between the cooking chamber and the external environment is an air path, i.e. in particular the data signal does not run through an electrical conductor at any section. In a further development, the antenna is arranged in the region of a door slot or door gap. This is advantageous because gap settings between the cooking chamber wall and the door usually result in slots through which electromagnetic waves can escape. The air path then runs, for example, through the door gap, in particular through a gap or slot between the door and the door flange. In a further development, the antenna can be arranged on the outside of a door pane, for example glued on, screwed on, printed with an electrically conductive foil such as copper or aluminum, or vapor-deposited. The antenna can also protrude into the door slot.

[0047] Since the control panel of an oven is usually made of radiation-permeable material (glass, plastic) and is located close to the oven door, a printed or physical antenna solution behind the control panel would also be conceivable. This has the advantage that the antenna cable to the transmitter / receiver can be permanently installed and does not have to be routed via a hinge system, as is the case with the oven door, which could potentially cause disadvantageous movement of the cable over time.

[0048] One embodiment provides for the air path to pass through an opening, particularly a slot, formed in the boundary, particularly through a ventilation slot formed in the cooking chamber wall. This is advantageously particularly easy to implement.

[0049] In one embodiment, the cooking appliance has a microwave function, in particular, it is a standalone microwave appliance or an oven / microwave combination appliance, in particular an oven with a microwave function. In a cooking appliance with a microwave function, microwave leakage occurs via one or more leakage paths, e.g., through a door gap. The intensity of the microwave leakage radiation is limited for safety reasons, e.g., by design measures such as providing a lambda / 4 trap at the door gap, a perforated grille in a door window, appropriately dimensioning openings in the cooking chamber wall, etc.

[0050] In one embodiment, the electromagnetic waves used to transport the data signals lie in a frequency range outside the microwave frequency band used for the microwave function. This has the advantage that the data signals are generally not attenuated as strongly as the microwave radiation, since the cooking appliance is designed for particularly effective attenuation of the leakage microwave radiation and not, or not as much, for attenuation in other wavelength or frequency ranges. The microwave frequency band includes, in particular, the frequencies of the microwaves generated by a microwave generating device in the cooking appliance or propagating in the cooking chamber. The microwave frequency band can, for example, lie in a range between 902 MHz and 928 MHz or in a range between 2.4 and 2.5 GHz.In general, and not limited to specific frequency bands, in particular ISM bands, in one embodiment the at least one leakage path causes an attenuation of microwaves and a lower attenuation for the data signals.

[0051] It is a further development that the frequency range for the data signals also lies within an ISM band, which brings regulatory advantages, especially in a different ISM band than the ISM band used for microwaves.

[0052] One design is that the frequency range used for data signals is the 433 MHz ISM band. Its frequencies lie between 433.05 MHz and 434.79 MHz. This offers the advantage that the antenna dimensions can be particularly practical.

[0053] However, if the cooking appliance does not have a microwave function, the ISM band used for the data signals can also be the ISM band typically used for microwaves in the region in question, e.g. the 902 MHz ISM band in the frequency range between 902 MHz and 928 MHz or the 2.4 GHz ISM band in the frequency range between 2.4 and 2.5 GHz.

[0054] If the device, particularly one with a microwave function, has at least one slot, one embodiment is that the slot is or has an attenuating effect on microwaves and serves as a resonator for the data signals or their frequency, thus leading to a high amplitude of the transmitted or received data signal. This corresponds to a matched slot antenna. Advantageously, a narrow slot is provided with a length corresponding to half the wavelength of the data signals; for example, if the data signals are located in the 433 MHz frequency band, this would be approximately 100 cm long.

[0055] 35 cm.

[0056] The slot can, for example, be a ventilation slot formed in the cooking chamber wall or a section of the door gap.

[0057] The object is also achieved by a system comprising a cooking appliance as described above and a functional unit to be arranged or arranged in the cooking chamber, which is equipped with a wireless transmitting and / or receiving device for the data signals, wherein, when the cooking chamber is closed - in particular also during a cooking process - data signals can be transmitted between this transmitting and / or receiving device and the transmitting and / or receiving circuit of the cooking appliance via at least one leakage path (i.e., can be coupled into the cooking chamber from the outside and / or decoupled from the cooking chamber to the outside). The system can be designed analogously to the cooking appliance, and vice versa, and has the same advantages.The transmitting and / or receiving circuit of the cooking appliance, and thus also the cooking appliance equipped with it, on the one hand, and the functional unit arranged in the cooking chamber, on the other hand, can therefore communicate with each other unidirectionally or bidirectionally via at least one leakage path, even when the cooking chamber is closed. The transmitting and / or receiving device of the functional unit can be designed to match the transmitting and / or receiving circuit of the cooking appliance, e.g., as a transmitter if the transmitting and / or receiving circuit of the cooking appliance has a receiver or transceiver, as a receiver if the transmitting and / or receiving circuit of the cooking appliance has a transmitter or transceiver, or as a transceiver.

[0058] The functional unit, which can also be referred to as an "application," can actively or automatically transmit data signals, such as measurement signals, via its transmitting and / or receiving device, e.g., at regular intervals. The functional unit can additionally or alternatively be interrogated by the transmitting and receiving circuit of the cooking appliance, e.g., by the transmitting and receiving circuit sending a data signal, e.g., comprising a control command or a query signal, to the functional unit and receiving a response signal in response, e.g., a measurement signal or a measured value. Additionally or alternatively, a data signal, e.g., comprising a query signal, can be sent from the functional unit inside the cooking chamber to the transmitting and receiving circuit outside the cooking chamber, whereupon the transmitting and receiving circuit then sends a response signal back to the functional unit. A clear data signal (e.g.,with high amplitude and / or low signal-to-noise ratio) is advantageous if the transmitting and receiving circuit of the cooking appliance and the transmitting and / or receiving device of the functional unit are active, i.e. in particular electrically operated, units.

[0059] The functional unit or application could, for example, be a core temperature sensor that transmits the temperature data it measures from a food item in the cooking chamber to the transmit and / or receive circuit. The signal can then be evaluated there, e.g., using analog and digital signal processing.

[0060] In addition or alternatively to a core temperature sensor, at least one unit from the group

[0061] - Humidity sensor;

[0062] - weighing unit;

[0063] - chemical sensor;

[0064] - status indicator;

[0065] - pressure sensor can be used.

[0066] The problem is further solved by a method in which data signals are transmitted between a functional unit arranged in a sealed cooking chamber of a cooking appliance and a transmitting and / or receiving circuit arranged in an external environment of the cooking chamber via at least one leakage path present between the cooking chamber and its external environment. The method can be designed analogously to the cooking appliance and the system, and vice versa, and has the same advantages.

[0067] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in conjunction with the following schematic description of an exemplary embodiment, which is explained in more detail in conjunction with the drawings. Figure 1 shows a sectional side view of a system comprising a cooking appliance and a functional unit housed in a sealed cooking chamber of the cooking appliance.

[0068] Fig. 1 shows a sectional side view of a sketch of a system 1, 3 with a cooking appliance 1 in the form of an exemplary oven / microwave combination appliance and a functional unit in the form of an exemplary core temperature sensor 3 accommodated in a closed cooking chamber 2 of the cooking appliance 1. The cooking chamber 2 is delimited by a cooking chamber wall, also referred to as a muffle 4 or oven, and a door 5 closing the front loading opening of the muffle 4. The cooking appliance 1 has a microwave generating device 6, for example semiconductor-based or designed as a magnetron, which generates microwaves in the 2.4 GHz ISM band, which are fed into the cooking chamber 2 when the microwave generating device 6 is activated.

[0069] On a rear wall of the muffle, behind a baffle 7, which also serves as an air guide plate, is a fan wheel 8, which, when rotated, circulates the air in the muffle 4. A ring heater (not shown) can be associated with the fan wheel 8, the operation of which, along with the simultaneous rotation of the fan wheel 8, enables hot air operation. For even air circulation, the baffle 7 is provided with air slots 7a. The fan wheel 8 is attached to an electrically conductive, e.g., metallic, motor shaft 9 of a drive motor 10 arranged outside the muffle 4 and rotates at the speed of the motor shaft 9. The fan wheel 8, the motor shaft 9, and the drive motor 10 can collectively be referred to as a "hot fan assembly."

[0070] The spit of the core temperature probe 3 is inserted into the food G. The spit contains at least one temperature sensor (not shown), which can be used to sense a ("core") temperature inside the food G. The measured voltages sensed by the temperature sensor can optionally be digitized using a circuit located in a handle 11 of the core temperature probe 3. An active transmitter 12, also located in the handle 11, transmits the measured values ​​as analog or digital data signals via radio in the 433 MHz ISM band. For example, the measured values ​​of a carrier wave in the 433 MHz ISM band can be amplitude and / or angle modulated accordingly. The data signals propagate in the cooking chamber 2 through the slots in the baffle 7 to the fan wheel 8 and to the motor shaft 9, into which the data signals are coupled.The fan wheel 8 and the motor shaft 9 thus act as an antenna, with the data signals coupled into them being transmitted via the motor shaft 9 out of the cooking chamber 2, e.g., to the drive motor 10 and its suspension. This creates a comparatively strong stray field SF in the 433 MHz ISM band outside the cooking chamber 2 in the area of ​​the motor shaft 9 and the drive motor 10, in which the data signals are contained.

[0071] The stray field SF is picked up by a freestanding antenna 13 spaced apart from the motor unit (comprising at least the motor shaft 9, its suspension, and the drive motor 10) and transmitted as a "received signal" via a shielded or unshielded antenna cable 14, here, for example, a coaxial cable, to a receiver 15 or transceiver. In the receiver 15, the data signals are extracted from the received signal, e.g., demodulated, and transmitted, e.g., to a control unit 16 and / or other components of the cooking appliance 1, such as a screen, etc. In particular, the receiver 15 can convert the data signals into digital temperature values ​​using an analog-to-digital converter. The digital temperature values ​​can, for example, be transmitted as a digital bus signal to another component for further processing.

[0072] The control unit 16 can then control the operation of the cooking appliance 1 based on the temperature measurement values ​​of the core temperature sensor 3 contained in the data signals, e.g. vary the energy input and / or end a cooking process.

[0073] There is therefore a leakage path LP for radio waves in the 433 MHz ISM band from the transmitter 12, through the cooking chamber 2 and further through the slots in the baffle 7 to the fan wheel 8 and the motor shaft 9 and then along the motor shaft 9 to the outside, and from there by means of the stray field SF via an air gap 17 to the antenna 13. At the same time, the cooking appliance 1 is designed such that the coupling of microwaves in the 2.4 GHz band via the motor shaft 9 is strongly attenuated and cannot exceed a set limit. The hot fan assembly 8 to 10 does not need to be mechanically modified; for example, the fan wheel 8 and the motor shaft 9 do not need to be specially adapted for coupling the data signals. This avoids potentially complex and error-prone mechanics, problems with signal reception, and additional costs.In particular, since the signal pickup by the antenna 13 is not galvanic but contactless using the electromagnetic stray field SF, no sliding contact or brush constructions are required, which could lead to contact problems over time, disrupting reliable reception of the data signal and potentially causing acoustic interference. Rather, signal pickup using the electromagnetic stray field SF provides a very simple way to pick up the extracted data signal and transmit it to the receiver 15.

[0074] For this purpose, it is sufficient, for example, to use an electrical antenna cable 14 in the form of an electrically insulated wire, the end region of which facing the motor shaft 9 is stripped and thus serves as the antenna 13. The antenna 13 is coupled to the motor shaft 9 and / or the hot air motor 10 inductively or capacitively (at a short distance across the air gap 17). The other end of the wire is connected to the input of the receiver 15. It is also possible to use a shielded cable as the antenna cable 14 to prevent the coupling of electromagnetic interference. This cable 14 is advantageously designed as a coaxial cable or as a twisted pair cable, whereby the electromagnetic shield can be connected, for example, to the receiver 15. In many cases, a further improvement is achieved if the antenna cable 14 is routed close to large ground planes (housing panel, intermediate rear panel, etc.).This allows impedance ratios to be kept largely constant and electromagnetic interference to be largely avoided.

[0075] The shape of the antenna 13 is fundamentally unlimited and can, for example, be formed as a coil. The antenna 13 can be laid entirely or in sections spaced apart around the motor shaft, particularly for inductive coupling. In principle, the amplitude of the received signal coupled into the antenna 13 can be increased in the case of a coil by increasing the number of turns. In the case of a capacitive connection, an amplitude increase can be achieved by reducing the distance or increasing the areas of the capacitively coupling elements of a correspondingly designed antenna 13.

[0076] The receiver 15 is advantageously designed as receiver electronics, which may necessitate the use of a printed circuit board 15a. The printed circuit board 15a then has, for example, the antenna 13 and the receiver 15. The antenna cable 14 can then optionally be omitted. The antenna 13 and, if present, the antenna cable 14 can be implemented as conductor tracks on the printed circuit board 15a, e.g., by electroplating, printing, etc. The receiver 15 with the printed circuit board 15a, the antenna 13, and, if present, the antenna cable 14 can then be viewed as components of a uniformly manageable receiver module 18. The modular design offers the advantage that no high-frequency signals need to be transported via additional cables. This, in turn, saves costs and reduces the potential interference caused by and on the data signals.In a further development, the circuit board 15a has a recess that is arranged at least partially around the motor shaft 9, e.g., in a U-shape. An antenna 13 designed as a coupling surface for the stray field SF is arranged in particular on an edge region that is arranged around the motor shaft 9, e.g., in a U-shape.

[0077] If the hot-air fan assembly 8 to 10 is considered an electromagnetic source, a certain source impedance of the antenna 13 is also present. To achieve the best possible pickup of the stray field SF, the antenna 13 and, if applicable, the antenna cable 14 should be matched to the electromagnetic impedance of the hot-air fan assembly 8 to 10. This can be achieved, for example, by adjusting the antenna cable 14 and / or by means of an LC matching network at the receiver input 15.

[0078] Of course, the present invention is not limited to the embodiment shown.

[0079] In addition or alternatively, at least one further antenna may be provided to pick up a stray field present outside the muffle and may be connected to a receiver or transceiver which converts the signals received by the antenna into digital data signals.

[0080] 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., as long as this is not explicitly excluded, e.g. by the expression "exactly one", etc. A numerical specification can also include exactly the specified number as well as a usual tolerance range, as long as this is not explicitly excluded.

[0081] List of reference symbols

[0082] 1 cooking appliance

[0083] 2 cooking chamber

[0084] 3 core temperature sensors

[0085] 4 muffles

[0086] 5 Door

[0087] 6 Microwave generating device

[0088] 7 Baffle wall

[0089] 7a Ventilation slot

[0090] 8 Fan wheel

[0091] 9 Motor shaft

[0092] 10 Drive motor

[0093] 11 Handle of the core temperature probe

[0094] 12 channels

[0095] 13 Antenna

[0096] 14 Antenna cable

[0097] 15 recipients

[0098] 15a circuit board

[0099] 16 Control unit

[0100] 17 Air gap

[0101] 18 Receiver module

[0102] G Food to be cooked

[0103] LP leakage path

[0104] SF stray field

Claims

Patent claims 1. Cooking appliance (1), comprising - a closable cooking chamber (2) with at least one leakage path (LP) for electromagnetic waves between the cooking chamber (2) and its external environment and - a free-standing antenna (13) arranged on an external environment of the cooking chamber (2) for data signals transmitted via the at least one leakage path (LP), - which is connected to a transmitting and / or receiving circuit (15) for the data signals.

2. Cooking appliance (1) according to claim 1, wherein - at least one leakage path (LP) has an electrical conductor (9) leading through a boundary (4, 5) of the cooking chamber (2), - the antenna (13) is arranged at a distance from this electrical conductor (9) and - the antenna (13) is arranged to exchange the data signals with the electrical conductor (9).

3. Cooking appliance (1) according to claim 2, wherein the electrical conductor (9) is part of a functional part (8 - 10) projecting from the external environment of the cooking chamber (2) into the cooking chamber (2).

4. Cooking appliance (1) according to claim 3, wherein the electrical conductor (9) - a motor shaft (9) of a hot air motor (10), - a grill heater, - a lamp construction, - a sensor element, - an actuator element, - an electrical supply line and / or - is a fastening element.

5. Cooking appliance (1) according to one of the preceding claims, wherein at least one leakage path (LP) between the cooking chamber (2) and the external environment is an air path.

6. Cooking appliance (1) according to one of the preceding claims, wherein the air path leads through a slot formed in particular in the boundary (4, 5) of the cooking chamber (2).

7. Cooking appliance (1) according to one of the preceding claims, wherein the cooking appliance (1) has a microwave function (6).

8. Cooking appliance (1) according to one of the preceding claims, wherein the waves used to transport the data signals lie in a frequency range outside the microwave frequency band used for the microwave function, in particular within an ISM band.

9. Cooking appliance (1) according to claim 8, wherein the waves used to transport the data signals are in the frequency range of the 433 MHz ISM band.

10. Cooking appliance (1) according to one of claims 7 to 9, wherein the at least one leakage path (LP) causes an attenuation of microwaves and a lower attenuation for the data signals.

11. Cooking appliance (1) according to claims 6 to 10, wherein the slot is attenuating for microwaves and serves as a resonator for the data signals.

12. System, comprising a cooking appliance (1) according to one of the preceding claims and a functional unit (3) to be arranged in the cooking chamber (2), which is equipped with a wireless transmitting and / or receiving device (12) for the data signals, wherein, when the cooking chamber (2) is closed, data signals can be transmitted between this transmitting and / or receiving device (12) and the transmitting and / or receiving circuit (15) of the cooking appliance (1) via at least one leakage path (LP).

13. Method in which data signals are transmitted between a device in a closed cooking chamber (2) of a cooking appliance (1) arranged functional unit (3) and a transmitting and / or receiving circuit (15) arranged in an external environment of the cooking chamber (2) via at least one leakage path (LP) present between the cooking chamber (2) and its external environment.

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