EP4380314A1 - Appareil ménager doté d'une fonction à micro-ondes et son procédé de fonctionnement - Google Patents

Appareil ménager doté d'une fonction à micro-ondes et son procédé de fonctionnement Download PDF

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Publication number
EP4380314A1
EP4380314A1 EP23205443.7A EP23205443A EP4380314A1 EP 4380314 A1 EP4380314 A1 EP 4380314A1 EP 23205443 A EP23205443 A EP 23205443A EP 4380314 A1 EP4380314 A1 EP 4380314A1
Authority
EP
European Patent Office
Prior art keywords
magnetron
pulse width
household appliance
anode current
power supply
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP23205443.7A
Other languages
German (de)
English (en)
Inventor
Olaf BLÖMKER
Eckhard Pöhler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Miele und Cie KG
Original Assignee
Miele und Cie KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Miele und Cie KG filed Critical Miele und Cie KG
Publication of EP4380314A1 publication Critical patent/EP4380314A1/fr
Pending legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/66—Circuits
    • H05B6/68—Circuits for monitoring or control
    • H05B6/681—Circuits comprising an inverter, a boost transformer and a magnetron
    • H05B6/682—Circuits comprising an inverter, a boost transformer and a magnetron wherein the switching control is based on measurements of electrical values of the circuit
    • H05B6/683—Circuits comprising an inverter, a boost transformer and a magnetron wherein the switching control is based on measurements of electrical values of the circuit the measurements being made at the high voltage side of the circuit
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B2206/00—Aspects relating to heating by electric, magnetic, or electromagnetic fields covered by group H05B6/00
    • H05B2206/04—Heating using microwaves
    • H05B2206/043—Methods or circuits intended to extend the life of the magnetron

Definitions

  • the invention relates to a household appliance for heating foodstuffs, comprising an interior for receiving the foodstuffs and a magnetron for generating microwave radiation.
  • the invention further relates to a method for operating such a household appliance.
  • Household appliances in particular cooking appliances with a microwave function, are known from the state of the art, such as microwave ovens or ovens with a microwave function.
  • the microwave radiation is usually generated by a magnetron, for example at 2.4 GHz, and emitted into the interior in order to heat and/or cook food containing liquid.
  • the microwave radiation sets the liquid contained in the food in motion, so that the energy of the microwave radiation is converted into heat and the food is heated.
  • a large part of the microwave radiation or even all of the microwave radiation is reflected back to the magnetron. There is then a risk that the magnetron will heat up and be damaged.
  • load sensors to detect low or non-existent loads, for example to detect high levels of microwave radiation reflected from the interior or an increase in the temperature of the magnetron.
  • the disadvantage is that it is expensive to provide such sensors in a household appliance and the sensors are also usually susceptible to failure.
  • the pulse width of the anode current in particular the starting pulse width of the anode current, of the magnetron is detected.
  • the load quantity in the cooking chamber is derived from this pulse width. If there is no load in the cooking chamber (no load), then the starting pulse width is greatest.
  • the start pulse width includes at least the first switching edge of the anode current signal, in particular the start pulse widths of the first 2 to 9 switching edges of the anode current signal.
  • an average value is formed when evaluating several switching edges.
  • an extreme individual value, in particular the largest individual value, of the switching edges taken into account can be used for the evaluation.
  • the object is achieved by a household appliance for heating a foodstuff, comprising an interior space for receiving the foodstuff, a magnetron for generating microwave radiation, a switching power supply for operating the magnetron and a control unit for controlling the switching power supply, wherein the household appliance is designed to detect and evaluate the pulse width of the anode current of the magnetron.
  • the start pulse width of the periodically recurring anode current signal is used.
  • the start pulse width comprises the first up to 100 microseconds of the anode current pulse.
  • the household appliance is designed, for example, as a microwave device or oven with a microwave function, with the interior being designed as a cavity that can be closed by means of a door.
  • An inlet opening is then provided on the interior, behind which the magnetron is arranged, so that microwave radiation generated by the magnetron is coupled into the interior through the inlet opening.
  • the microwave radiation forms a standing wave in the interior and acts on a food placed inside the oven to heat it.
  • the microwave radiation has a frequency of 2.4 GHz and is therefore in the ISM band.
  • a magnetron is a vacuum tube for generating electromagnetic waves in the microwave range and consists, for example, of a cylindrical hot cathode (oxide or reservoir cathode) in the center of the vacuum tube, which is surrounded by a solid, cylindrical anode made of copper, with the anode having slots arranged in a radial pattern and running parallel to the cathode.
  • a switching power supply or switching power supply is an electronic assembly that converts an unstabilized input voltage into a constant output voltage and is designed in particular as a high-voltage switching power supply.
  • the solution to the problem with the household appliance described above therefore includes the teaching that the pulse width of the anode current is recorded and evaluated when the magnetron is in operation.
  • the invention has recognized that the amount of loading in the interior can be quantified based on the pulse width and, in particular, that an empty interior can be recognized.
  • a high pulse width therefore corresponds to a low loading and vice versa.
  • This relationship is based on the fact that the current applied to the anode by the switching power supply has a low pulse width in itself, but reflected microwave radiation overlays the anode current and thus increases the pulse width.
  • the pulse width is therefore a measure of the microwave radiation reflected from the interior to the magnetron or the amount of energy arriving at the magnetron.
  • the household appliance can then suggest or carry out appropriate measures to avoid damage to the magnetron.
  • the detection of the low load state or the empty interior does not require any separately provided means such as load sensors, so that the household appliance is designed simply and cost-effectively.
  • the switching power supply is designed to detect the pulse width of the anode current of the magnetron.
  • the anode current is directly applied to the switching power supply, so that detection by the switching power supply can be particularly simple.
  • the switching power supply is also preferably designed to output the pulse width of the anode current of the magnetron as a value.
  • the value represents the pulse width, for example numerically, and is therefore directly proportional to the pulse width.
  • the switching power supply outputs the pulse width as a digital value.
  • Such a value can be received by means designed to evaluate the pulse width and evaluated particularly easily. In particular, a digital value can be evaluated particularly efficiently using data processing tools and corresponding algorithms.
  • the control unit is preferably designed to evaluate the pulse width of the anode current of the magnetron.
  • the control unit usually has means that are suitable for data processing, so that an evaluation by the control unit can be designed particularly easily and without additional means. Insofar as the switching power supply is already connected to the control unit for the exchange of signals, the value output by the switching power supply can be received by the control unit for evaluation.
  • the object is also achieved by a method for operating a household appliance as described above, wherein the pulse width of the anode current of the magnetron is recorded and evaluated.
  • the evaluation is carried out with regard to a deviation of the pulse width from a pulse width applied to the magnetron by the switching power supply, so that a loading state of the household appliance or of the interior with a liquid-containing medium can be detected based on the evaluation of the detected pulse width.
  • the method therefore enables the detection of a low or empty loading state and an associated risk of damage to the magnetron without additional means having to be provided in the household appliance.
  • appropriate measures can then be proposed or carried out by the household appliance, for example by the control unit.
  • the method according to the second aspect of the invention has the advantages described above with regard to the first aspect of the invention.
  • a notification about a low load state is issued to a person using the household appliance, for example via a display element of the household appliance or via a data connection to a terminal device of the person.
  • the first limit value is selected, for example, according to a load classified as "low". The operator is then able to recognize the low load and the associated risk of damage to the household appliance and can, for example, reduce the power of the magnetron or stop heating after a relatively short time in order to avoid damage to the household appliance.
  • the power of the magnetron is reduced above a second limit value of the detected pulse width.
  • the second limit value is selected, for example, according to a load classified as “low” or “very low”. Reducing the power is beneficial as it reduces/prevents damage to the magnetron.
  • the operation of the magnetron is stopped above a third limit value of the detected pulse width.
  • the third limit value is selected, for example, according to a load classified as "very low” or "empty".
  • first element for example "first element”, “second element” and “third element”
  • this numbering is intended purely to differentiate the designation and does not represent a dependency of the elements on one another or a mandatory order of the elements.
  • a device or a method does not have to have a "first element” in order to be able to have a “second element”.
  • the device or method can also have a "first element” and a “third element” without necessarily having a "second element”.
  • Several units of an element of a single numbering can also be provided, for example several "first elements”.
  • a first limit value can be greater than, less than or equal to a second or third limit value.
  • Figure 1 shows a kitchen unit 1 with several kitchen cabinets 2.1, 2.2, 2.3 and a household appliance 3 designed as an oven, a stove 4 and an extractor hood 5 arranged above the stove 4.
  • the household appliance 3 has an interior 11 covered by a door 3.1, several control elements 3.2 and a display element 3.3 and also has a microwave function in addition to at least one baking function. Notifications can be issued to a person using the household appliance 3 via the display element 3.2, for example.
  • the household appliance 3 can also have other functions such as a steam cooking function or a pyrolysis function.
  • FIG 2 shows a highly simplified representation of components of the household appliance 3, namely the interior 11 and a magnetron 12 that interacts with the interior 11.
  • the magnetron 12 is arranged, for example, behind an inlet opening of the interior 11, so that microwave radiation generated by the magnetron 12 can radiate through the inlet opening into the interior 11. The microwave radiation can then also get from the interior 11 to the magnetron 12, as shown by a double arrow.
  • the household appliance 3 also has a switched-mode power supply 13 that interacts with the magnetron 12, which outputs an output voltage and thus operates the magnetron 12 to generate microwave radiation.
  • the switched-mode power supply 13 can detect electrical variables applied to the magnetron 12, so that there is bilateral interaction, as shown by the double arrow.
  • the switched-mode power supply 13 detects an anode current applied to the magnetron 12 or its pulse width.
  • the household appliance 3 has a control unit 14 which is designed to exchange signals and/or data with the switching power supply 13, as shown by a double arrow.
  • the control unit 14 is designed to output a value from the switching power supply 13 which determines the pulse width of the anode current The evaluation is aimed at detecting a low or empty loading state of the interior 11, for example based on a pulse width / a value above a limit value.
  • Figure 3 shows a diagram of a value in nanoseconds representing the pulse width of the anode current from tests with a test setup and several loadings of the interior 11.
  • the switching power supply 13 records the anode current of the magnetron 12 and generates from it the Figure 3 shown digital values per load.
  • the absolute pulse widths of the various loads depend on the specific test setup, which is not described in detail here, but not their relationship to one another.
  • a first pulse width 8.1 of the anode current results for a glass bowl with 1000 ml of water positioned in the interior 11 of approximately 700 nanoseconds.
  • a second pulse width 8.2 of the anode current results for a glass bowl with 100 ml of water positioned in the interior 11 of approximately 1100 nanoseconds.
  • a third pulse width 8.3 of the anode current results for an empty glass bowl positioned in the interior 11 of approximately 1900 nanoseconds.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Control Of High-Frequency Heating Circuits (AREA)
  • Electric Ovens (AREA)
EP23205443.7A 2022-11-29 2023-10-24 Appareil ménager doté d'une fonction à micro-ondes et son procédé de fonctionnement Pending EP4380314A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
BE20225966A BE1031082B1 (de) 2022-11-29 2022-11-29 Haushaltsgerät mit Mikrowellenfunktion und Verfahren zum Betreiben desselben

Publications (1)

Publication Number Publication Date
EP4380314A1 true EP4380314A1 (fr) 2024-06-05

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP23205443.7A Pending EP4380314A1 (fr) 2022-11-29 2023-10-24 Appareil ménager doté d'une fonction à micro-ondes et son procédé de fonctionnement

Country Status (2)

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EP (1) EP4380314A1 (fr)
BE (1) BE1031082B1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4835353A (en) * 1987-12-28 1989-05-30 General Electric Company Filament power conpensation for magnetron
JPH02278691A (ja) 1989-04-20 1990-11-14 Mitsubishi Electric Corp 電源装置
DE102018105901A1 (de) * 2018-03-14 2019-09-19 Miele & Cie. Kg Gargerät, umfassend einen Garraum und ein Magnetron zur Erzeugung von elektromagnetischer Energie, und Verfahren zum Betrieb eines derartigen Gargeräts

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4835353A (en) * 1987-12-28 1989-05-30 General Electric Company Filament power conpensation for magnetron
JPH02278691A (ja) 1989-04-20 1990-11-14 Mitsubishi Electric Corp 電源装置
DE102018105901A1 (de) * 2018-03-14 2019-09-19 Miele & Cie. Kg Gargerät, umfassend einen Garraum und ein Magnetron zur Erzeugung von elektromagnetischer Energie, und Verfahren zum Betrieb eines derartigen Gargeräts

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BE1031082A1 (de) 2024-06-20
BE1031082B1 (de) 2024-06-24

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