HOUSEHOLD APPLIANCE WITH TEMPERATURE DETECTOR

Description

[0001] The invention relates to a household appliance comprising at least one circuit component, a control unit for controlling the at least one circuit component, and a temperature detector coupled to the control unit. The invention also relates to a method for operating such a household appliance. The invention is particularly advantageously applicable to microwave cooking appliances such as standalone microwave cookers or ovens, e.g., conventional ovens, with microwave functionality.

[0002] Previously known semiconductor amplifiers in microwave ovens use a feedthrough network that is connected downstream of at least one transistor. The semiconductor amplifier includes, among other things, a circulator to protect the transistor from microwave power reflected back from the cooking chamber, a unit for detecting or measuring the reflected microwave power, and a load for dissipating the reflected microwave power.

[0003] DE 298 039 05 U1 discloses a cooktop for measuring the temperature of cookware, comprising a cooktop frame on which a sensor assembly is mounted, which has a receiving part attached below the cooktop frame and a tubular sensor part with a viewing window that is vertically slidable in the frame, through which heat radiation falls when the sensor part is extended upwards through a frame opening onto an infrared sensor arranged in the sensor part, thereby enabling non-contact measurement of the wall temperature of a heat-radiating cooking appliance placed on the cooktop.

[0004] DE 10 305 368 A1 discloses an electric motor comprising several components such as a stator, rotor, windings, and bearings, the operating-dependent temperatures of which are monitored, and these components having temperature sensors for determining their absolute temperatures. The temperature sensors are thermal radiation sensors that enable non-contact detection and / or measurement of the emitted heat.

[0005] WO 2015 / 037004 A1 concerns the measurement of the temperature of objects under strong electromagnetic fields.

[0006] US 5 645 748 A relates to a method and a system for simultaneously sterilizing a large number of metallic surgical instruments using microwave radiation and for preventing arcing of the metallic surgical instruments.

[0007] US 2010 / 115785 A1 generally deals with drying an object, optionally using RF energy. In many embodiments of the invention, the object is clothing.

[0008] EP 2 182 774 A1 t relates to a microwave heating device for heating an object to be heated, i.e. a heating target, by irradiation with a microwave.

[0009] US 4 996 403 A refers generally to the technology of microwave heating control systems and, in particular, to the control of the boiling process of a liquid in a microwave applicator.

[0010] US 2003 / 121913 A1 relates to a microwave heater and, in particular, to a microwave heater with a microwave heating element mounted on the surface of a heating plate onto which food is placed in a heating chamber.

[0011] GB 2 310 733 A concerns a heat control system for a microwave oven suitable for heating packaged food sealed with a lid or plastic film.

[0012] WO 2004 / 091260 A1 concerns a high-frequency heating device.

[0013] US 2013 / 278345 A1 refers generally to electronic circuits and specifically to microwave adapters for solid-state microwave oscillators.

[0014] US 5 021 620 A relates to a high-frequency heater in which a DC voltage obtained by rectifying a high-frequency voltage generated by an inverter circuit in a rectifier circuit is applied to a magnetron and thereby drives the magnetron, and in particular to such a high-frequency heater which is equipped with compensating means for compensating an anode current of the magnetron in order to keep it at a predetermined value.

[0015] US 5 389 335 A relates to a system and a method for heating to high temperatures and for short periods of time, and in particular to a system and a method for heating to high temperatures and for short periods of time heat-sensitive material that preserves the selected biological properties of the heat-sensitive material while achieving a multiple log reduction of pathogens, such as viruses, in the heat-sensitive material.

[0016] It is the Task the present invention aims to overcome at least some of the disadvantages of the prior art and, in particular, to provide a possibility for a particularly safe and reliable operation of a microwave household appliance, especially a microwave cooking appliance.

[0017] This problem is solved according to the features of a household microwave oven according to claim 1 and the method steps of claim 14. Further preferred embodiments are defined in the dependent claims.

[0018] The problem is solved by a household appliance comprising at least one circuit component, a control device for controlling the at least one circuit component, and at least one temperature detector for sensing the temperature of at least one circuit component, wherein the control device is coupled to the temperature detector and is configured to control the household appliance based on temperature measurement data measured by the temperature detector, and wherein the at least one temperature detector is an IR detector.

[0019] This household appliance has the advantage that temperature measurement allows monitoring of a circuit component for abnormal or temperature-critical operation. Temperature-critical operation can include, for example, operation after exceeding a component's limit temperature or an excessively rapid temperature rise.

[0020] The use of a specific IR detector offers the advantage of exceptionally high detection speed and precision in temperature measurement, as thermal inertia plays virtually no role. This, in turn, enables particularly fast and / or accurate temperature control of the monitored circuit component.

[0021] Another advantage of using an IR detector is that it has virtually no effect on the circuit components, as it typically has no metallic parts that need to be brought into close proximity with them. In contrast, contact thermocouples such as platinum resistance thermometers can interfere with this circuit component if they touch it or are located near it. Furthermore, the connecting leads of contacting thermocouples can also adversely affect signal pickup.

[0022] Furthermore, contact thermocouples exhibit higher thermal inertia than an IR detector, especially if the thermocouple must be positioned at a distance from the circuit component being monitored. In particular, if the thermocouple must be positioned at a distance from the circuit component to avoid interfering with it, sufficiently accurate and instantaneous temperature measurement of the circuit component, and therefore a sufficiently rapid response to thermal overload of the component, is not possible with thermocouples.

[0023] The household appliance can be a household cooking appliance.

[0024] The at least one circuit component that can be sensed or detected is therefore located within the field of view of the IR detector.

[0025] The IR detector can detect exactly one or more circuit components. This requires that exactly one or more circuit components be located within the IR detector's field of view or detection range. The household appliance can have one or more IR detectors.

[0026] It is a further point to note that at least one IR detector is a spatially non-resolving IR detector. Such an IR detector is particularly inexpensive and robust, and its data is also very easy to analyze.

[0027] It is also an advanced feature that the IR detector is a spatially resolved IR detector. This offers the advantage of obtaining additional information and, moreover, distinguishing between multiple heat sources within the IR detector's field of view, e.g., several circuit components.

[0028] The IR detector can have one or more IR sensors. For example, the IR detector can use one or more thermopiles or thermocouples as IR sensors. Alternatively, the IR detector can be an IR-sensitive semiconductor chip, such as a CCD sensor. In addition to the at least one IR sensor, the IR detector can have optics positioned in front of the at least one IR sensor. These optics can include, for example, at least one lens, at least one aperture, etc.

[0029] In cases where multiple circuit components are monitored by one or more IR detectors, the individual component temperatures can be precisely distinguished using dedicated sensors. Unlike temperature measurements with a thermocouple, for example, no measurement error arises from the superposition of temperatures from different circuit components. In particular, this allows for the detection of asymmetrical thermal loads on the circuit components and, consequently, even the smallest defects in a single component.

[0030] It is an advantageous embodiment in the case where an IR detector detecting image by image or pixel by pixel is set up and arranged to sense the temperature of several circuit components, or where several circuit components are located in the field of view or detector area of ​​the IR detector, that local temperature ranges in an image recorded by the IR detector can be assigned to the respective circuit components.

[0031] A circuit component can be understood as a component of a circuit or circuit network. The circuit component can be an electrical or electronic component. For example, a circuit component can be a resistor, a capacitor, an inductor, or similar. A circuit component can also be a semiconductor component. A circuit component can be an integrated circuit or contain an integrated circuit.

[0032] It is a further development that the control device is set up to control at least one temperature-sensing circuit component based on temperature measurement data measured by the temperature detector.

[0033] The control unit, which is configured to control at least one sensable circuit component based on temperature measurement data from the temperature detector, may, in one embodiment, include the triggering or triggering of at least one action by the household appliance based on the occurrence of an event determined by the temperature measurement data. The occurrence of the event may include operation within a critical temperature range or a foreseeable occurrence within the critical temperature range. The action may be issuing a warning to a user and / or triggering at least one countermeasure to lower the temperature.

[0034] Setting up the control device may include programming it.

[0035] One embodiment involves at least one circuit component detectable by the IR detector being a high-frequency (HF) circuit component. The IR detector is particularly advantageous in this configuration because HF components are strongly affected by the presence of nearby metallic objects. In this embodiment, contacting thermocouples, such as platinum resistance thermometers, must be positioned at a distance from the HF circuit component being detected to avoid interference, for example, on a heat sink of the circuit component. Consequently, due to the thermal inertia or thermal resistance of the overall system with thermocouples, precise and instantaneous temperature measurement of an HF circuit component is not possible, and therefore, neither is a sufficiently rapid response to a thermal overload of the HF circuit component.

[0036] It is further knowledge that at least one RF component is an RF transistor. It is further knowledge that at least one circuit component is a part or component of an amplifier circuit.

[0037] It is also a further development that at least one circuit component is part of a feedthrough network. The feedthrough network can be connected downstream of the RF transistor. The feedthrough network, together with the RF transistor, can form part of the amplifier circuit or be equivalent to the amplifier circuit. The feedthrough network can include, among other things, a circulator to protect the RF transistor, a unit for detecting reflected microwave power (e.g., a directional coupler), and / or a final load for dissipating microwave power reflected back from a cooking chamber.

[0038] In one configuration, the household appliance is a microwave oven and at least one RF component is a microwave component. The microwave oven may contain a magnetron to generate the microwaves.

[0039] A microwave oven can be a microwave cooking appliance. A microwave cooking appliance can have a cooking chamber into which microwaves can be fed to heat food placed inside. A microwave cooking appliance can be a standalone microwave cooking device. Alternatively, a microwave cooking appliance can be an oven, such as a conventional oven, with microwave functionality.

[0040] The microwave oven can also be a sterilizer for cooking utensils, etc.

[0041] It is also a possible configuration that the IR detector has at least one IR sensor which is aligned with the at least one circuit component to be detected. This advantageously allows for a particularly simple and compact design as well as a particularly distortion-free view of the field of view.

[0042] Furthermore, one embodiment involves positioning the IR detector at a distance from the at least one circuit component being detected. This minimizes any interference with this component. It also allows for more flexible positioning of the IR detector. This distance between the IR detector and the at least one circuit component being detected specifically includes the presence of a gap or space, particularly an air gap, between them. This gap provides particularly effective RF isolation between the at least one circuit component being detected and the IR detector, especially for RF circuit components.

[0043] It is a further development that at least one temperature-sensing circuit component is housed in a shielded enclosure, and the IR detector is located outside this enclosure. This is particularly advantageous for RF circuits or RF circuit components, as it means that the IR detector's electrical leads (e.g., a data and / or power supply line) are also located entirely outside the enclosure, thus preventing interference with the measurement and / or data transmission caused by high-frequency fields. This also eliminates the need for cable penetrations through the enclosure. Furthermore, it avoids the presence of electrical leads inside the enclosure, which could also interfere with RF circuit components.

[0044] Another embodiment of the IR detector comprises at least one IR sensor and at least one IR optical fiber, and IR light emitted by the at least one circuit component to be detected passes through the IR optical fiber onto the at least one IR sensor. This offers the advantage of particularly flexible positioning of the IR detector. The IR optical fiber can, in particular, comprise one or more fiber optic cables.

[0045] Furthermore, one design feature is that the IR optical fiber touches at least one circuit component to be detected by the IR detector. This allows for particularly accurate temperature measurement. Since the IR optical fiber is non-metallic, but made of materials such as plastic or glass, it does not interfere with the circuit component, especially RF components.

[0046] Furthermore, it is a configuration that includes at least one action involving a reduction of the power supplied to at least one sensable circuit component. This allows the temperature of this circuit component to be reduced. It is a further development in that the control device is alternatively or additionally configured to control at least one other circuit component in such a way that the power supplied to the at least one sensable circuit component is reduced or can be reduced. The reduction of power can be a reduction of electrical power and / or microwave power. The reduction of power can include operating the sensable circuit component at only partial power or even deactivating it completely. Thus, reducing the power is a possible countermeasure to reducing the temperature of the sensable circuit component.

[0047] An alternative or additional configuration involves the sensing circuit component being an RF circuit component, with at least one action comprising a change in at least one RF parameter. The control unit is thus configured to change at least one RF parameter based on temperature measurements of an RF circuit component taken by the temperature detector. Particularly in microwave ovens, this can reduce the power of the reflected microwaves, thereby lowering the temperature in an RF circuit component—for example, an RF transistor. An RF parameter can include, for example, the amplitude, frequency, and / or phase shift of microwaves radiated into a cooking chamber. Changing RF parameters can be equivalent to changing an operating point. Therefore, changing the RF parameters is another possible countermeasure to reduce the temperature of the sensing circuit component.

[0048] One further configuration involves the occurrence of an event determined by the temperature measurement data, which includes the detection of a temperature-critical operation of at least one circuit component. The control unit is therefore specifically designed to modify the control of at least one sensable circuit component based on the detection of a (temperature-)critical operation of at least one circuit component. This prevents overheating and potential damage to the circuit component.

[0049] In one further embodiment, temperature-critical operation involves reaching or exceeding a predefined threshold through a temporal temperature gradient. The control unit is thus specifically designed to detect temperature-critical operation by determining whether a temporal temperature gradient reaches or exceeds a predefined threshold. Advantageously, the calculated temperature gradient can be used to approximate reflected power, particularly microwave power reflected from an oven cavity. If the temperature gradient rises excessively quickly, the control of the appliance can be modified to reduce the reflected power before a critical temperature is reached at the monitored circuit component.Furthermore, the temporal temperature gradient can be used to detect or diagnose component aging, component drift and / or impermissible deviations from known operating conditions.

[0050] One further configuration involves temperature-critical operation being triggered by a temperature reaching or exceeding a predefined threshold. The control unit is therefore designed to detect temperature-critical operation by verifying that a temperature reaches or exceeds at least a predefined threshold. Thus, an overtemperature, a warning temperature, and / or a critical limit temperature, etc., can be detected at this circuit component using the IR detector.

[0051] It is a further development step that temperature-critical operation is recognized based on a temperature profile.

[0052] The control device can therefore be programmed to recognize, based on an instantaneous temperature value, a temperature profile and / or a temporal temperature gradient, whether the temperature-sensed component is in normal operation (without excessively strong / rapid heating) or in critical operation (with excessively strong / rapid heating).

[0053] In another embodiment, the household appliance is a microwave oven comprising a semiconductor amplifier with an RF transistor and a feedthrough network downstream of the RF transistor. The temperature detector is arranged and configured to sense the temperature of at least the RF transistor, and the control unit is configured to trigger at least one action, based on the occurrence of an event determinable by the temperature measurement data. This action leads to a reduction in the temperature of the RF transistor or triggers a countermeasure to reduce the temperature of the RF transistor. The occurrence of the event can—as already described above—include, for example, the operation of the RF transistor in a critical temperature range or the anticipated occurrence of the RF transistor in the critical temperature range.This design has the advantage that it allows for a particularly quick and reliable response to a critical or potentially critical temperature increase of the RF transistor.

[0054] In particular, monitoring the RF transistor using an IR detector eliminates the need for a circulator previously required to protect the RF transistor. Additionally or alternatively, the end load can be omitted. Additionally or alternatively, a measuring device for reflected microwave radiation can be omitted. If necessary, the feedthrough network can be eliminated entirely. All these improvements result in significant cost savings by eliminating components, compared to the only minor additional costs incurred by including the IR detector. Furthermore, losses due to the feedthrough network can be reduced, leading to higher efficiency. In other words, the microwave oven can be designed without a circulator, without an end load, without a measuring device for reflected microwave radiation, or even without a feedthrough network altogether.

[0055] The problem is also solved by a method for operating a household appliance comprising at least one circuit component, a control unit for controlling the at least one circuit component, and at least one temperature detector for sensing the temperature of at least one circuit component, wherein the control unit is coupled to the at least one temperature detector, and wherein, in the method, the temperature of at least one circuit component is sensed by means of at least one IR detector as the at least one temperature detector, and the control unit controls the household appliance based on the sensed temperature. The method can be designed analogously to the household appliance and has the same advantages.

[0056] The properties, features and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more easily understood in connection with the following schematic description of an exemplary embodiment, which will be explained in more detail in conjunction with the drawings. Fig. 1 shows a section view in side view of a sketch of a microwave cooking appliance according to a first embodiment and Fig. 2 shows a section view in side view of a sketch of a microwave cooking appliance according to a second embodiment.

[0057] Fig. 1Figure 1 shows a section of a household appliance in the form of a microwave oven 1. The microwave oven 1 has a cooking chamber 2, which is enclosed by a cooking chamber wall 3. Outside the cooking chamber wall 3 – here: above a ceiling of the cooking chamber wall 3 – a housing 4 is arranged, which shields an RF area 5. Within the RF area 5 is a circuit component in the form of an RF transistor 6, which forms part of an amplifier circuit for introducing microwaves into the cooking chamber 2.

[0058] An IR detector 7 is arranged on an outer surface of the housing 4. The IR detector 7 is directed through a window 14 in the housing 4 directly at the RF transistor 6 and can sense or measure the temperature of the RF transistor 6. The IR detector 7 is therefore spaced apart from the RF transistor 6. The IR detector 7 can have at least one IR sensor 8.

[0059] The IR detector 7 is coupled to a control unit 9, by means of which the amplifier circuit, and optionally also the RF transistor 6 directly, can be controlled. This coupling can be established via a data cable 10. Temperature measurement data, for example, is transmitted from the IR detector 7 to the control unit 9 via the data cable 10. The control unit 9 is configured to control the microwave oven 1 based on temperature measurement data from the IR detector 7. Specifically, the control unit 9 is configured to trigger at least one action based on the occurrence of an event determined by the temperature measurement data.

[0060] The at least one action may involve reducing the power input to the RF transistor 6. This power may, in particular, refer to the microwave power reflected back from the cooking chamber 2. Alternatively or additionally, the at least one action may involve changing at least one microwave parameter (such as the amplitude, frequency, and / or phase shift of the microwaves radiated into the cooking chamber 2) that affects the reflected power.

[0061] The event that occurs may include the detection of temperature-critical operation of at least one circuit component. Temperature-critical operation may, for example, include reaching or exceeding a predefined threshold due to a time-dependent temperature gradient and / or reaching or exceeding a predefined threshold due to an (instantaneous) temperature.

[0062] The control unit 9 is specifically designed to trigger at least one action, based on the occurrence of an event determined by the temperature measurement data sensed by the RF transistor 6, which leads to a reduction in the temperature of the RF transistor 6. This allows the microwave oven 1 to react quickly to an impending or actual overheating of the RF transistor 6 and take appropriate countermeasures. As a result, the amplifier circuit of the microwave oven 1 may dispense with a circulator, a final load, a measuring device for the reflected microwave radiation, or even a feedthrough network altogether.

[0063] Fig. 2Figure 1 shows a section of a sketch of a microwave cooking appliance 11 according to a second embodiment of the invention, in a sectional side view. The microwave cooking appliance 11 is similar to the microwave cooking appliance 1, except that it now has an IR detector 12 comprising at least one IR sensor 8 and at least one IR optical waveguide 13. The IR optical waveguide 13 projects through the window 14 into the RF area 5.

[0064] The IR-light coupling end face of the IR optical waveguide 13 touches the RF transistor 6 (or at least has only a very small gap to it). Therefore, IR light emitted by the RF transistor 6 is guided through the IR optical waveguide 13 to the at least one IR sensor 8. This embodiment has the advantage of very low measurement interference from other heat sources.

[0065] Although the IR optical waveguide 13 is shown here as a straight line, it can also be curved. The IR sensor 8 does not need to be aligned with the RF transistor 6, but it can be. This allows for a particularly wide range of positioning options for the IR sensor 8.

[0066] Naturally, the present invention is not limited to the embodiment shown. The invention is defined by the accompanying claims.

[0067] In general, "ein", "eine", etc. can be understood to mean singular or plural, especially in the sense of "at least one" or "one or more", etc., unless this is explicitly excluded, e.g. by the expression "exactly one", etc.

[0068] A numerical specification can also include exactly the specified number as well as a normal tolerance range, unless this is explicitly excluded. Reference symbol list

[0069] 1 Microwave oven 2 Cooking chamber 3 Cooking chamber wall 4 Housing 5 RF area 6 RF transistor 7 IR detector 8 IR sensor 9 Control unit 10 Data cable 11 Microwave oven 12 IR detector 13 IR optical fiber 14 Window

Claims

1. Household microwave appliance (1; 11), - having a solid-state amplifier with a HF transistor (6), a control facility (9) for actuating the HF transistor (6) and at least one temperature detector (7; 12), which is coupled to the control facility (9), - wherein the at least one temperature detector (7; 12) is arranged and configured for sensing a temperature of the HF transistor (6), and - the control facility (9) is configured to actuate the household microwave appliance (1; 11) on the basis of an occurrence of an event which can be determined by temperature measurement data measured by the temperature detector (7; 12), to trigger at least one action, - said at least one action comprising a triggering of at least one countermeasure for lowering a temperature at the HF transistor (6), characterised in that - the at least one temperature detector is an IR detector (7; 12), - the at least one countermeasure comprises changing at least one HF parameter.

2. Household microwave appliance (1; 11) according to claim 1, characterised in that the IR detector (7; 12) has at least one IR sensor (8), which is oriented towards the HF transistor (6).

3. Household microwave appliance (1) according to claim 2, characterised in that the IR detector (7) is spaced apart from the HF transistor (6).

4. Household microwave appliance (11) according to one of the preceding claims, characterised in that the IR detector (12) has at least one IR sensor (8) and at least one IR light waveguide (13) and IR light emitted by the HF transistor (6) passes through the IR light waveguide (13) and falls on the at least one IR sensor (8).

5. Household microwave appliance (11) according to claim 2, characterised in that the IR detector (12) has at least one IR sensor (8) and at least one IR light waveguide (13) and IR light emitted by the HF transistor (6) passes through the IR light waveguide (13) and falls on the at least one IR sensor (8) and the IR light waveguide (13) touches the HF transistor (6) .

6. Household microwave appliance (1; 11) according to one of the preceding claims, characterised in that the at least one action comprises a reduction of a power fed to the HF transistor (6).

7. Household microwave appliance (1; 11) according to one of the preceding claims, characterised in that the occurrence of the event which can be determined by the temperature measurement data comprises an identification of a temperature-critical operation of the HF transistor (6).

8. Household microwave appliance (1; 11) according to claim 7, characterised in that the temperature-critical operation comprises a predefined threshold value being reached or exceeded by a temporal temperature gradient.

9. Household microwave appliance (1; 11) according to one of claims 7 or 8, characterised in that the temperature-critical operation comprises a predefined threshold value being reached or exceeded by a temperature.

10. Household microwave appliance (1; 11) according to one of the preceding claims, characterised in that it is embodied without a circulator.

11. Household microwave appliance (1; 11) according to one of the preceding claims, characterised in that the household microwave appliance (1; 11) is embodied without an end load.

12. Household microwave appliance (1; 11) according to one of the preceding claims, characterised in that the household microwave appliance (1; 11) is embodied without a measuring facility for measuring the reflected microwave radiation.

13. Household microwave appliance (1; 11) according to one of the preceding claims, characterised in that the household microwave appliance (1; 11) is embodied without a feedthrough network for measuring the reflected microwave radiation.

14. Method for operating a household microwave appliance (1; 11) according to one of the preceding claims, in which - a temperature of the HF transistor (6) is sensed by means of the IR detector (7; 12) and - the control facility (9) actuates the household microwave appliance (1; 11) on the basis of the sensed temperature.