EP0321767A2 - Arrangement for the electrothermal treatment of food - Google Patents

Arrangement for the electrothermal treatment of food Download PDF

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Publication number
EP0321767A2
EP0321767A2 EP19880120278 EP88120278A EP0321767A2 EP 0321767 A2 EP0321767 A2 EP 0321767A2 EP 19880120278 EP19880120278 EP 19880120278 EP 88120278 A EP88120278 A EP 88120278A EP 0321767 A2 EP0321767 A2 EP 0321767A2
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EP
European Patent Office
Prior art keywords
microwave
food
energy
waveguide
directional coupler
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Ceased
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EP19880120278
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German (de)
French (fr)
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EP0321767A3 (en
Inventor
Julius Dipl.-Ing. Husslein
Helmut Dipl.-Ing. Hess
Wolfgang Dipl.-Ing. Beifuss
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BOSCH-SIEMENS HAUSGERAETE GMBH
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Individual
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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
    • 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
    • H05B6/6447—Method of operation or details of the microwave heating apparatus related to the use of detectors or sensors
    • 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

Definitions

  • the present invention relates to an arrangement for the thermal treatment of food by applying microwave energy in a domestic oven using a microwave waveguide, in which microwave energy is coupled in from a microwave generator and from which microwave energy is coupled out into a food treatment area.
  • microwave ovens or microwave ovens with or without additional thermal heating sources are used, into which the microwave energy is fed into a cooking space which is sealed off in a microwave-tight manner by means of a microwave generator, namely a magnetron.
  • An approved microwave frequency of 2.45 GHz is used.
  • the coupled microwave energy is usually 600 to 700 watts.
  • the microwaves coupled into the cooking space penetrate more or less deeply and intensively into the food to be cooked, depending on the type and nature of the food to be cooked, and the microwave energy is converted there into thermal energy and is used to carry out cooking processes or to defrost food.
  • different power levels can be set in known cookers up to this maximum output. There are various options for this.
  • microwave power it is possible, for example, to change the microwave power by switching capacitances on and off in the magnetron circuit.
  • Another widely used measure for reducing the maximum power is given by the fact that the maximum power is generated in a clocked manner, ie that in relatively short intervals Microwave transmission is interrupted for predetermined pause times.
  • the setting of the suitable microwave power for the respective cooking process is the responsibility of the operator in known household appliances. Thus, the operator must take great care to avoid inappropriate, unfavorable or even harmful settings of the microwave energy.
  • any available microwave power can be set up to the maximum power and this power is also generated by the microwave generator and coupled into the cooking space, even if it contains relatively little or no food that is capable of using the microwave energy converted into heat energy by absorption.
  • the generated microwave energy the existence of which is not or hardly discernible outside the oven, is undesirably reduced within the oven and partially fed back to the microwave generator. If this type of incorrect operation lasts longer, impairments and damage cannot fail to occur within the unit.
  • an object of the present invention to provide an arrangement for the thermal treatment of food by exposure to microwave energy in household ovens, in which it is excluded as far as possible that inappropriate, in particular inappropriate high microwave outputs are generated for the exposure to the microwave space.
  • An arrangement which meets these requirements is characterized according to the invention in that a microwave directional coupler which influences the setting of the microwave generator via an evaluation circuit and / or controls a display device is arranged in the region of the waveguide.
  • the arrangement according to the invention is characterized in that the evaluation circuit, the measurement results of the microwave directional coupler representative of the microwave field strength movement in the food treatment area as microwave demand criteria depending on the quantity and the type of food to be thermally treated for the Control of the microwave energy to be emitted by the microwave generator evaluates. This ensures that, depending on the situation in the cooking space, a corresponding and / or maximum microwave power is processed in terms of control technology.
  • the arrangement according to the invention is characterized in that the evaluation circuit evaluates the measurement results of the microwave directional coupler which are representative of the microwave field strength assignment in the food treatment area as process flow control values for controlling the microwave energy to be emitted by the microwave generator.
  • the directional coupler arranged in the area of the waveguide can detect microwave field strength occupancy differences that are representative of changes in the state of the food. While microwave food is being applied to the food, it is converted into heat energy in the food. The consequence of this is changes in the absorption capacity of the food for microwave energy. These differences are particularly large and can therefore be recorded particularly cheaply when the food to be frozen is converted to the thawed state or when the boiling state is reached. Especially with these changes in the state of the food, it is expedient to make changes in the supply and measurement of the microwave power.
  • the arrangement according to the invention is characterized in that the measurement results detected by the evaluation circuit via the microwave directional coupler are provided for the adjustment of the microwave waveguide, including the microwave coupling and decoupling elements.
  • the individual device can thus be detected with respect to the conduction of the microwave energy, starting from the microwave generator via the waveguide into the cooking space, and the geometry of adjustable coupling elements in the waveguide and coupling elements from the waveguide can be changed such that each derives an optimally optimal, low-reflection microwave transition.
  • the arrangement according to the invention is characterized in that in the area of the microwave waveguide for detecting the energy emitted by the microwave generator and for the opposing energy components, one of two directional couplers, at the one outputs of which the measuring device is connected and the other of which Outputs are equipped with a reflection-free termination, are arranged anti-parallel.
  • the figure shows a schematic representation of the basic components of a microwave oven.
  • Microwave energy is coupled into a cooking chamber GR of the microwave oven, within which cooked food GG to be treated thermally is introduced via a rotating antenna MA.
  • This rotating antenna MA takes over the microwave energy from a waveguide HL, which in turn takes over the microwave energy from a microwave generator MG, a magnetron.
  • a power control unit LS is arranged, which contains a high-voltage transformer and rectifier and capacitor units in a known manner.
  • the setting values relating to the microwave power to be radiated into the cooking space GR and the duration of this irradiation are entered into a control logic AL via a display / operating panel AE, which logic logic controls these input values for the
  • Control of the power control unit implements.
  • the set values can be displayed on the AE display / control panel.
  • a microwave directional coupler RK is coupled to the waveguide HL, an output line A1 of which detects measured values which correspond to the microwave energy traveling from the microwave generator MG in the direction of the cooking chamber GR through the waveguide HL and whose second output A2 detects measured values for opposing microwave energy.
  • the relation of these microwave energy migrations and thus the relation of the measured quantities detected by the outputs A1 and A2 of the directional coupler RK gives a good indication of the reason, whatever the reason, that the microwave power emitted by the microwave generator MG in the cooking space GR actually does is absorbed, essentially by the introduced food GG.
  • the outputs A1 and A2 of the directional coupler RK are fed to a comparison circuit VS, which carries out a relation between the two detected and supplied measured values and from this forwards a criterion to the control logic AL.
  • the power control LS for the microwave generator MG is influenced and readjusted in accordance with the energy requirement within the cooking chamber GR and the entered values. If, for example, due to the very high microwave energy return detected by the microwave directional coupler RK, it can be assumed that there is no food or food with only a very small mass in the cooking chamber GR, the control logic AL switches the power control LS off after a short switch-on time.
  • the control logic AL can contain values that have been permanently entered for carrying out standard cooking processes. By superimposing the values detected by the microwave directional coupler RK, which currently represent the cooking state of the food, the progress of the individual process steps can be controlled and modifications of these steps can be carried out.
  • the arrangement of the microwave directional coupler RK is also useful for optimally and individually setting the positions of the coupling and decoupling elements of the waveguide for each arrangement.
  • a measured value as processed at the outputs A 1 and A2 of the microwave directional coupler RK, is sent to the diplay of the display / control panel AE.
  • the position of the magnetron MG and the rotating antenna MA to the waveguide HL can then be changed until optimal results are signaled.
  • two eccentric bearings arranged one inside the other can be used for this purpose.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Control Of High-Frequency Heating Circuits (AREA)
  • Constitution Of High-Frequency Heating (AREA)
  • Surgical Instruments (AREA)
  • Electric Ovens (AREA)

Abstract

In the waveguide, via which microwave energy generated by a microwave generator is supplied into a domestic oven for heating food, there is arranged a microwave directional coupler which influences the control of the microwave generator, via an evaluation circuit, and/or controls an indicator device. <IMAGE>

Description

Die vorliegende Erfindung bezieht sich auf eine Anordnung zur wärmetechnischen Behandlung von Lebensmitteln durch Beaufschlagung von Mikrowellenenergie in einem Haushaltsofen unter Verwendung eines Mikrowellen-Hohlleiters, in dem Mikrowellen­energie von einem Mikrowellengenerator eingekoppelt und aus dem Mikrowellenener­gie in einen Lebensmittel-Behandlungsbereich ausgekoppelt wird.The present invention relates to an arrangement for the thermal treatment of food by applying microwave energy in a domestic oven using a microwave waveguide, in which microwave energy is coupled in from a microwave generator and from which microwave energy is coupled out into a food treatment area.

Im Haushalt sind Mikrowellenöfen oder Mikrowellenherde mit oder ohne zusätzlichen thermischen Heizquellen in Verwendung, in die mittels einem Mikrowellen-Generator, nämlich einem Magnetron, über Hohlleiter, die Mikrowellenenergie in einen mikro­wellendicht abgeschlossenen Garraum eingespeist wird. Dabei wird eine zugelasse­ne Mikrowellen-Frequenz von 2,45 GHz verwendet. Die eingekoppelte Mikrowellen­energie beträgt üblicherweise 600 bis 700 Watt. Die in den Garraum eingekoppelten Mikrowellen dringen je nach Art und Beschaffenheit des Gargutes mehr oder weni­ger tief und intensiv in dieses Gargut ein und die Mikrowellenenergie wird dort in Wärmeenergie umgesetzt und dient zur Durchführung von Garungsprozessen oder zum Auftauen von Gargut. Je nach gewünschter Behandlungsweise und Art des Gargutes können bei bekannten Herden bis zu dieser maximalen Leistung unterschiedliche Lei­stungsstufen eingestellt werden. Dafür bieten sich verschiedene Möglichkeiten an. So ist es moglich, die Mikrowellenleistung beispielsweise durch Zu- und Abschalten von Kapazitäten im Magnetron-Schaltkreis zu verändern. Eine weitere verbreitet ange­wendete Maßnahme zur Reduzierung der Maximalleistung ist dadurch gegeben, daß die Maximalleistung getaktet erzeugt wird, d.h., daß in relativ kurzen Abständen die Mikrowellenaussendung für vorgegebene Pausenzeiten unterbrochen wird. Die Einstel­lung der geeigneten Mikrowellenleistung für den jeweiligen Garungsvorgang obliegt bei bekannten Haushaltsgeräten ausschließlich der Bedienungsperson. Somit muß die Bedienungsperson hohe Sorgfalt aufwenden, um unzweckmäßige, ungünstige oder gar schädliche Einstellungen der Mikrowellenenergie zu vermeiden. So kann prinzipiell je­de zur Verfügung stehende Mikrowellenleistung bis hin zur Maximalleistung einge­stellt werden und diese Leistung wird vom Mikrowellen-Generator auch erzeugt und in den Garraum eingekoppelt, auch wenn in diesem relativ wenig oder garkein Gar­gut enthalten ist, das in der Lage ist, die Mikrowellenenergie durch Absorption in Wärmeenergie überzuführen. Die erzeugte Mikrowellenenergie, deren Existenz außer­halb des Herdes nicht oder kaum zu erkennen ist, wird in derartigen Fällen inner­halb des Herdes in unerwünschter Weise abgebaut und teilweise zum Mikrowellen-­Generator zurückgekoppelt. Bei länger anhaltender derartiger Fehlbedienung können Beeinträchtigungen und Schädigungen innerhalb der Einheit nicht ausbleiben.In the household, microwave ovens or microwave ovens with or without additional thermal heating sources are used, into which the microwave energy is fed into a cooking space which is sealed off in a microwave-tight manner by means of a microwave generator, namely a magnetron. An approved microwave frequency of 2.45 GHz is used. The coupled microwave energy is usually 600 to 700 watts. The microwaves coupled into the cooking space penetrate more or less deeply and intensively into the food to be cooked, depending on the type and nature of the food to be cooked, and the microwave energy is converted there into thermal energy and is used to carry out cooking processes or to defrost food. Depending on the desired type of treatment and the type of food to be cooked, different power levels can be set in known cookers up to this maximum output. There are various options for this. It is possible, for example, to change the microwave power by switching capacitances on and off in the magnetron circuit. Another widely used measure for reducing the maximum power is given by the fact that the maximum power is generated in a clocked manner, ie that in relatively short intervals Microwave transmission is interrupted for predetermined pause times. The setting of the suitable microwave power for the respective cooking process is the responsibility of the operator in known household appliances. Thus, the operator must take great care to avoid inappropriate, unfavorable or even harmful settings of the microwave energy. In principle, any available microwave power can be set up to the maximum power and this power is also generated by the microwave generator and coupled into the cooking space, even if it contains relatively little or no food that is capable of using the microwave energy converted into heat energy by absorption. In such cases, the generated microwave energy, the existence of which is not or hardly discernible outside the oven, is undesirably reduced within the oven and partially fed back to the microwave generator. If this type of incorrect operation lasts longer, impairments and damage cannot fail to occur within the unit.

Aufbauend auf diesen Erkenntnissen ist es Aufgabe der vorliegenden Erfindung, eine Anordnung zur wärmetechnischen Behandlung von Lebensmitteln durch Beaufschlagung mit Mikrowellenenergie in Haushaltsöfen bereitzustellen, bei der möglichst ausge­schlossen wird, daß unzweckmäßige, insbesondere unzweckmäßig hohe Mikrowellen-­Leistungen für die Beaufschlagung des Mikrowellenraumes erzeugt werden.Based on these findings, it is an object of the present invention to provide an arrangement for the thermal treatment of food by exposure to microwave energy in household ovens, in which it is excluded as far as possible that inappropriate, in particular inappropriate high microwave outputs are generated for the exposure to the microwave space.

Eine Anordnung, die diesen Anforderungen gerecht wird, ist erfindungsgemäß dadurch gekennzeichnet, daß im Bereich des Hohlleiters ein die Anstellung des Mikrowel­len-Generators über eine Auswerteschaltung beeinflussender und/oder eine Anzeige­einrichtung ansteuernder Mikrowellen-Richtkoppler angeordnet ist.An arrangement which meets these requirements is characterized according to the invention in that a microwave directional coupler which influences the setting of the microwave generator via an evaluation circuit and / or controls a display device is arranged in the region of the waveguide.

Die Verwendung eines derartigen Richtkopplers im Bereich des Hohlleiters eröffnet die Möglichkeit zu erfassen, solche Mikrowellenleistung in Relation zu der vom Mi­krowellen-Generator erzeugten Mikrowellenleistung, die in Richtung zum Garraum den Hohlleiter durchläuft, in Gegenrichtung verlaufend vorliegt. Je weniger Mikro­wellen-Leistung innerhalb des Garraums im Gargut in Wärmeenergie umgesetzt wird, desto mehr Mikrowellenenergie wird im Hohlleiter in Relation zur durch den Mikro­wellen-Generator erzeugten Mikrowelle zurückgekoppelt. Mit Hilfe der erfindungsge­mäßen Anordnung kann diese Relation der eingekoppelten und zurückgekoppelten Mi­krowellenenergie steuertechnisch dazu genutzt werden, eine Mikrowellenerzeugung gemäß den tatsächlichen Verhältnissen innerhalb des Garraums zu optimieren.The use of such a directional coupler in the region of the waveguide opens up the possibility of detecting such microwave power in the opposite direction in relation to the microwave power generated by the microwave generator, which passes through the waveguide in the direction of the cooking chamber. The less microwave power is converted into heat energy within the cooking space in the food, the more microwave energy is fed back in the waveguide in relation to the microwave generated by the microwave generator. With the aid of the arrangement according to the invention, this relation of the coupled-in and fed-back microwave energy can be used in terms of control technology to optimize microwave generation in accordance with the actual conditions within the cooking space.

Nach einer bevorzugten Ausgestaltung ist die erfindungsgemäße Anordnung dadurch gekennzeichnet, daß die Auswerteschaltung, die für den Mikrowellen-Feldstärkenbe­wegung im Lebensmittel-Behandlungsbereich repräsentativen Meßergebnisse des Mi­krowellen-Richtkopplers als Mikrowellen-Bedarfskriterien in Abhängigkeit von der Menge und der Art der wärmetechnisch zu behandelnden Lebensmittel für die An­steuerung der vom Mikrowellen-Generator abzugebenden Mikrowellenenergie auswert­et. Somit wird erreicht, daß je nach Situation im Garraum eine entsprechende und/­oder maximale Mikrowellenleistung ansteuertechnisch verarbeitet wird. Nach einer anderen weitergebildeten Ausgestaltung ist die erfindungsgemäße Anordnung dadurch gekennzeichnet, daß die Auswerteschaltung, die für die Mikrowellen-Feldstärkenbele­gung im Lebnsmittel-Behandlungsbereich repräsentativen Meßergebnisse des Mikrowel­len-Richtkopplers als Prozeßablauf-Steuerwerte zur Ansteuerung der durch den Mi­krowellen-Generator abzugebenden Mikrowellenenergie auswertet. So können bei­spielsweise durch den im Bereich des Hohlleiters angeordneten Richtkoppler Mikro­wellen-Feldstärken-Belegungsunterschiede erfaßt werden, die repräsentativ sind für Zustandsänderungen des Garguts. Mährend der Beaufschlagung des Garguts mit Mi­krowellenenergie wird diese im Gargut in Wärmeenergie umgesetzt. Die Folge da­von sind Veränderungen in der Aufnahmefähigkeit des Garguts für Mikrowellenener­gie. Besonders groß sind diese Unterschiede und damit besonders günstig zu erfassen, wenn das Gargut zum gefrorenen Zustand in den aufgetauten Zustand übergeführt ist oder wenn der Siedezustand erreicht wird. Gerade bei diesen Zustandsänderungen des Garguts ist es zweckmäßig, Änderungen in der Zufuhr und Bemessung der Mikrowel­lenleistung vorzunehmen.According to a preferred embodiment, the arrangement according to the invention is characterized in that the evaluation circuit, the measurement results of the microwave directional coupler representative of the microwave field strength movement in the food treatment area as microwave demand criteria depending on the quantity and the type of food to be thermally treated for the Control of the microwave energy to be emitted by the microwave generator evaluates. This ensures that, depending on the situation in the cooking space, a corresponding and / or maximum microwave power is processed in terms of control technology. According to another refined embodiment, the arrangement according to the invention is characterized in that the evaluation circuit evaluates the measurement results of the microwave directional coupler which are representative of the microwave field strength assignment in the food treatment area as process flow control values for controlling the microwave energy to be emitted by the microwave generator. For example, the directional coupler arranged in the area of the waveguide can detect microwave field strength occupancy differences that are representative of changes in the state of the food. While microwave food is being applied to the food, it is converted into heat energy in the food. The consequence of this is changes in the absorption capacity of the food for microwave energy. These differences are particularly large and can therefore be recorded particularly cheaply when the food to be frozen is converted to the thawed state or when the boiling state is reached. Especially with these changes in the state of the food, it is expedient to make changes in the supply and measurement of the microwave power.

Nach einer anderen bevorzugten Maßnahme ist die erfindungsgemäße Anordnung da­durch gekennzeichnet, daß die von der Auswerteschaltung über den Mikrowellen-­Richtkoppler erfaßten Meßergebnisse zum Abgleich des Mikrowellen-Hohlleiters ein­schließlich der Mikrowellen-Ein- und Auskoppelorgane bereitgestellt sind. Mit Hilfe der erfindungsgemäß gegebenenfalls angeordneten Anzeigeeinrichtung kann somit das einzelne Gerät bezüglich der Leitung der Mikrowellenenergie, ausgehend vom Mikro­wellen-Generator über den Hohlleiter in den Garraum erfaßt werden und die Geo­metrie vo verstellbaren Einkoppelorganen in den Hohlleiter und Auskoppelorganen aus dem Hohlleiter so verändert werden, daß jeweils ein möglichst optimaler, reflexions­armer Mikrowellenübergang ableiten läßt.According to another preferred measure, the arrangement according to the invention is characterized in that the measurement results detected by the evaluation circuit via the microwave directional coupler are provided for the adjustment of the microwave waveguide, including the microwave coupling and decoupling elements. With the aid of the display device optionally arranged according to the invention, the individual device can thus be detected with respect to the conduction of the microwave energy, starting from the microwave generator via the waveguide into the cooking space, and the geometry of adjustable coupling elements in the waveguide and coupling elements from the waveguide can be changed such that each derives an optimally optimal, low-reflection microwave transition.

Nach einer bevorzugten Ausgestaltung ist die erfindungsgemäße Anordnung dadurch gekennzeichnet, daß im Bereich des Mikrowellen-Hohlleiters zur Erfassung der vom Mikrowellen-Generator abgestrahlten Energie und für die gegenläufigen Energiekom ponenten je einer von zwei Richtkopplern, an deren einen Ausgänge die Meßeinrich­tung angeschlossen sind und deren andere Ausgänge mit einem reflexionsfreien Ab­schluß ausgestattet sind, antiparallel angeordnet sind. Es ist zwar theoretisch und in manchen Fällen auch praktisch möglich, brauchbare Mikrowellenerfassungen mittels eines an den Mikrowellen-Hohlleiter angekoppelten Richtkoppler für Mikrowellen­energie-Transporte in beiden Richtungen zu halten, es ist aber meßtechnisch, insbe­sondere dann, wenn bereits geringfügige Mikrowellenenergie-Verläufe erfaßt werden sollen, für jede moglich Mikrowellen-Laufrichtung einen Richtkoppler anzuordnen, der an einem Ausgang einen praktisch reflexionsf reien Abschluß aufweist, so daß aus diesem Bereich keine das Meßergebnis verfälschende Einflüsse zu erwarten und zu berücksichtigen sind.According to a preferred embodiment, the arrangement according to the invention is characterized in that in the area of the microwave waveguide for detecting the energy emitted by the microwave generator and for the opposing energy components, one of two directional couplers, at the one outputs of which the measuring device is connected and the other of which Outputs are equipped with a reflection-free termination, are arranged anti-parallel. Although it is theoretically and in some cases also practically possible to hold usable microwave detections by means of a directional coupler for microwave energy transports coupled to the microwave waveguide in both directions, it is measurement-related, in particular if small microwave energy profiles are already to be detected to arrange a directional coupler for each possible microwave direction, which has a practically reflection-free termination at an output, so that no influences falsifying the measurement result can be expected and taken into account from this range.

Ein nach Merkmalen der Erfindung ausgestattetes Ausführungsbeispiel ist anhand der Zeichnung im folgenden näher beschrieben.An embodiment equipped according to the features of the invention is described in more detail below with reference to the drawing.

Die Figur zeigt eine schematisierte Darstellung der prizipiellen Baueinheiten eines Mikrowellenherdes.The figure shows a schematic representation of the basic components of a microwave oven.

In einen Garraum GR des Mikrowellenherdes, innerhalb welchem in einem Gefäß wärmetechnisch zu behandelndes Gargut GG eingebracht ist, wird Mikrowellenenergie über eine Drehantenne MA eingekoppelt. Diese Drehantenne MA übernimmt die Mi­krowellenenergie aus einem Hohlleiter HL, welcher seinerseits die Mikrowellenener­gie von einem Mikrowellen-Generator MG, einem Magnetron, übernimmt. Zur An­steuerung dieses Magnetrons ist eine Leistungssteuerungs-Einheit LS angeordnet, welche in bekannter Weise einen Hochspannungstransformator sowie Gleichrichter- und Kondensator-Einheiten enthält. Diese und für den gesicherten Mikrowellenbetrieb erforderlichen Schaltelemente brauchen vorliegend nicht näher betrachtet werden.Microwave energy is coupled into a cooking chamber GR of the microwave oven, within which cooked food GG to be treated thermally is introduced via a rotating antenna MA. This rotating antenna MA takes over the microwave energy from a waveguide HL, which in turn takes over the microwave energy from a microwave generator MG, a magnetron. To control this magnetron, a power control unit LS is arranged, which contains a high-voltage transformer and rectifier and capacitor units in a known manner. These switching elements, which are required for safe microwave operation, need not be considered in the present case.

Über ein Anzeige-/Bedien-Tableau AE sind die Einstellwerte bezüglich der in den Garraum GR einzustrahlenden Mikrowellen-Leistung und der Zeitdauer dieser Ein­strahlung in eine Ansteuerlogik AL eingegeben, die diese Eingabewerte für dieThe setting values relating to the microwave power to be radiated into the cooking space GR and the duration of this irradiation are entered into a control logic AL via a display / operating panel AE, which logic logic controls these input values for the

Ansteuerung der Leistungssteuerung-Einheit umsetzt. Die eingestellten Werte können im Anzeige-/Bedien-Tableau AE angezeigt werden.Control of the power control unit implements. The set values can be displayed on the AE display / control panel.

An den Hohlleiter HL ist ein Mikrowellen-Richtkoppler RK angekoppelt, dessen eine Ausgangsleitung A1 Meßwerte erfassen, welche der vom Mikrowellen-Generator MG in Richtung zum Garraum GR durch den Hohlleiter HL wandernden Mikrowellenener­gie entsprechen und dessen zweiter Ausgang A2 Meßwerte für gegenläufige Mikro­wellenenergie erfaßt. Die Relation dieser Mikrowellenenergie-Wanderungen und damit die Relation der durch die Ausgänge A1 und A2 des Richtkopplers RK erfaßten Meßgrößen gibt eine gute Aussage darüber, aus welchem Grund auch immer beein­trächtigt, die vom Mikrowellen-Generator MG abgestrahlte Mikrowellen-Leistung im Garraum GR auch tatsächlich absorbiert wird, und zwar im wesentlichen durch das eingebrachte Gargut GG. Ist beispielsweise kein Gargut im Garraum GR angeordnet, so wird im Garraum GR auch keine wesentliche Energie verbraucht und die durch den Mikrowellen-Richtkoppler RK erfaßte rückläufige Mikrowellenenergie wird auf ein sehr hohes Maß in Relation zur eingekoppelten Mikrowellenenergie anwachsen. Auch eine Veränderung des Zustandes des Gargutes, beispielsweise vom gefrorenen zum aufgetauten Zustand wird ein meßtechnisch am Mikrowellen-Richtkoppler RK erfaßbares Ergebnis herbeiführen, da sich das Aufnahmevermögen des Garguts GG für Mikrowellenenergie in Abhängigkeit des Garungszustandes ändert. Auch unter­schiedliche Gargutarten haben unterschiedliche Mikrowellen-Aufnahmeeigenschaften.A microwave directional coupler RK is coupled to the waveguide HL, an output line A1 of which detects measured values which correspond to the microwave energy traveling from the microwave generator MG in the direction of the cooking chamber GR through the waveguide HL and whose second output A2 detects measured values for opposing microwave energy. The relation of these microwave energy migrations and thus the relation of the measured quantities detected by the outputs A1 and A2 of the directional coupler RK gives a good indication of the reason, whatever the reason, that the microwave power emitted by the microwave generator MG in the cooking space GR actually does is absorbed, essentially by the introduced food GG. If, for example, no food to be cooked is arranged in the cooking space GR, no substantial energy is consumed in the cooking space GR and the declining microwave energy detected by the microwave directional coupler RK will increase to a very high degree in relation to the coupled-in microwave energy. A change in the state of the food to be cooked, for example from the frozen to the thawed state, will also produce a result that can be measured by the microwave directional coupler RK, since the absorption capacity of the food to be cooked GG for microwave energy changes as a function of the cooking state. Different types of food also have different microwave absorption properties.

Die Ausgänge A1 und A2 des Richtkopplers RK sind einer Vergleichsschaltung VS zugeführt, welche eine Relation zwischen den beiden erfaßten und zugeführten Meß­werten durchführt und daraus ein Kriterium an die Ansteuerlogik AL weiterleitet. In Abhängigkeit davon wird die Leistungssteuerung LS für den Mikrowellen-Generator MG beeinflußt und entsprechend dem Energiebedarf innerhalb des Garraums GR und den eingegebenen Werten nachgeregelt. Wird beispielsweise aufgrund des sehr hohen, vom Mikrowellen-Richtkoppler RK erfaßten Mikrowellenenergie-Rücklaufs zu vermu­ten sein, daß sich kein Gargut oder Gargut nur mit sehr geringer Masse im Gar­raum GR befindet, so schaltet die Ansteuerlogik AL die Leistungssteuerung LS nach kurzer Einschaltzeit ab. Geringe Mengen von Gargut sind in dieser Zeitspanne erfah­rungsgemäß genügend wärmetechnisch behandelt; andererseits ist die Mikrowellen-­ Einstrahlung in den ohne Gargut bestückten Garraum GR praktisch nicht sehr pro­blematisch. Die Ansteuerlogik AL kann für die Durchführung von Standard-Garungs­prozessen fest eingegebene Werte gespeichert enthalten. Durch die Überlagerung der vom Mikrowellen-Richtkoppler RK erfaßten Werte, die den Garzustand des Gargutes aktuell repräsentieren, kann der Fortgang der einzelnen Prozeßschritte gesteuert und können Modifizierungen dieser Schritte vorgenommen werden.The outputs A1 and A2 of the directional coupler RK are fed to a comparison circuit VS, which carries out a relation between the two detected and supplied measured values and from this forwards a criterion to the control logic AL. Depending on this, the power control LS for the microwave generator MG is influenced and readjusted in accordance with the energy requirement within the cooking chamber GR and the entered values. If, for example, due to the very high microwave energy return detected by the microwave directional coupler RK, it can be assumed that there is no food or food with only a very small mass in the cooking chamber GR, the control logic AL switches the power control LS off after a short switch-on time. Experience has shown that small quantities of food to be cooked are sufficiently thermally treated during this period; on the other hand, the microwave Irradiation in the GR cooking space without food is practically not very problematic. The control logic AL can contain values that have been permanently entered for carrying out standard cooking processes. By superimposing the values detected by the microwave directional coupler RK, which currently represent the cooking state of the food, the progress of the individual process steps can be controlled and modifications of these steps can be carried out.

Die Anordnung des Mikrowellen-Richtkopplers RK ist auch dazu dienlich, die Posi­tionen der Ein- und Auskoppelelemente des Hohlleiters optimal und individuell für jede Anordnung einzustellen. Dazu wird ein, wie an den Ausgängen A 1 und A2 des Mikrowellen-Richtkopplers RK erfaßten Meßwerte verarbeitet an das Diplay des An­zeige/Bedien-Tableaus AE geleitet. Die Position des Magnetrons MG und der Dreh­antenne MA zum Hohlleiter HL kann dann so weit verändert werden, bis optimale Ergebnisse signalisiert werden. Dazu sind beispielsweise jeweils zwei ineinander an­geordnete Exzenterlagerungen verwendbar.The arrangement of the microwave directional coupler RK is also useful for optimally and individually setting the positions of the coupling and decoupling elements of the waveguide for each arrangement. For this purpose, a measured value, as processed at the outputs A 1 and A2 of the microwave directional coupler RK, is sent to the diplay of the display / control panel AE. The position of the magnetron MG and the rotating antenna MA to the waveguide HL can then be changed until optimal results are signaled. For example, two eccentric bearings arranged one inside the other can be used for this purpose.

Claims (5)

1. Anordnung zur wärmetechnischen Behandlung von Lebensmitteln durch Beauf­schlagung mit Mikrowellenenergie in einem Haushaltsofen unter Verwendung eines Mikrowellen-Hohlleiters, in den Mikrowellenenergie von einem Mikrowel­lengenerator eingekoppelt und aus dem Mikrowellenenergie in einen Lebensmit­tel-Behandlungsbereich ausgekoppelt wird, dadurch gekennzeich­net, daß im Bereich des Hohlleiters (HL) ein die Ansteuerung des Mikro­wellengenerators (M) über eine Auswerteschaltung (AS) beeinflussender und/­oder eine Anzeigeeinrichtung (EA) ansteuernder Mikrowellen-Richtkoppler (RK) angeordnet ist.1. Arrangement for the thermal treatment of food by exposure to microwave energy in a household oven using a microwave waveguide, into which microwave energy is coupled by a microwave generator and from which microwave energy is coupled out into a food treatment area, characterized in that in the area of the waveguide ( HL) a microwave directional coupler (RK) influencing the control of the microwave generator (M) via an evaluation circuit (AS) and / or controlling a display device (EA) is arranged. 2. Anordnung nach Anspruch 1, dadurch gekennzeichnet, daß die Auswerteschal­tung die für den Mikrowellen-Feldstärkenbelegung im Lebensmittel-Behand­lungsbereich repräsentativen Meßergebnisse des Mikrowellen-Richtkopplers (RK) als Mikrowellen-Bedarfskriterien in Abhängigkeit von der Menge und der Art der wärmetechnisch zu behandelnden Lebensmittel (GG) für die Ansteuerung der vom Mikrowellengenerator (MG) abzugebenden Mikrowellenenergie auswert­et.2. Arrangement according to claim 1, characterized in that the evaluation circuit for the microwave field strength assignment in the food treatment area representative measurement results of the microwave directional coupler (RK) as microwave demand criteria depending on the amount and type of food to be thermally treated ( GG) for the control of the microwave energy to be emitted by the microwave generator (MG). 3. Anordnung nach einem der Ansprüche 1 oder 2, dadurch gekennzeichnet, daß die Auswerteschaltung die für die Mikrowellen-Feldstärkenbelegung im Le­bensmittel-Behandlungsbereich (GR) repräsentativen Meßergebnisse des Mikro­wellen-Richtkopplers (RK) als Prozeßablauf-Steuerwerte zur Ansteuerung der durch den Mikrowellengenerator (MG) abzugebenden Mikrowellenenergie aus­wertet.3. Arrangement according to one of claims 1 or 2, characterized in that the evaluation circuit for the microwave field strength assignment in the food treatment area (GR) representative measurement results of the microwave directional coupler (RK) as process flow control values for controlling the by the microwave generator ( MG) evaluates microwave energy to be delivered. 4. Anordnung nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die von der Auswerteschaltung über den Mikrowellen-Richtkoppler (RK) erfaß­ten Meßergebnisse zum Abgleich des Mikrowellen-Hohlleiters (HL) einschließ­lich der Mikrowellen-Ein- und Auskoppelorgane bereitgestellt sind.4. Arrangement according to one of claims 1 to 3, characterized in that the measurement results detected by the evaluation circuit via the microwave directional coupler (RK) are provided for matching the microwave waveguide (HL) including the microwave coupling and decoupling members. 5. Anordnung nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß im Bereich des Mikrowellen-Hohlleiters (HL) zur Erfassung der vom Mikrowellen­generator abgestrahlten Energie und für die gegenläufigen Energiekomponenten je einer von zwei Richtkopplern (RK), an deren einen Ausgängen die Meßein­richtungen angeschlossen sind und deren andere Ausgänge mit einem reflexions­freien Abschluß ausgestattet sind, antiparallel angeordnet sind.5. Arrangement according to one of claims 1 to 4, characterized in that in the region of the microwave waveguide (HL) for detecting the energy emitted by the microwave generator and for the opposing energy components each one of two directional couplers (RK), at one of which outputs the Measuring devices are connected and the other outputs are equipped with a reflection-free termination, are arranged antiparallel.
EP19880120278 1987-12-23 1988-12-05 Arrangement for the electrothermal treatment of food Ceased EP0321767A3 (en)

Applications Claiming Priority (2)

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DE19873743919 DE3743919A1 (en) 1987-12-23 1987-12-23 ARRANGEMENT FOR THE HEAT-TREATMENT OF FOODSTUFFS
DE3743919 1987-12-23

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EP0321767A2 true EP0321767A2 (en) 1989-06-28
EP0321767A3 EP0321767A3 (en) 1991-05-02

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JP2581842B2 (en) * 1990-11-19 1997-02-12 動力炉・核燃料開発事業団 Microwave heating equipment
WO2011138680A2 (en) * 2010-05-03 2011-11-10 Goji Ltd. Spatially controlled energy delivery
DE102012006578A1 (en) * 2012-03-30 2013-10-02 Topinox Sarl Cooking apparatus e.g. microwave oven used in restaurant, irradiates high frequency radiation from high-frequency radiation source into cooking chamber, and evaluates reflected radio frequency radiation received by detector
ES2767721T3 (en) 2016-11-22 2020-06-18 Miele & Cie Procedure for heating a liquid by detecting a boiling point
DE102019128203B3 (en) * 2019-10-18 2021-04-22 Tq-Systems Gmbh Method for calibrating a microwave module, calibration system, microwave module and microwave device
DE102019128204B4 (en) * 2019-10-18 2021-05-06 Topinox Sarl Method for calibrating a microwave module, calibration system, microwave module and cooking device

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US4210795A (en) * 1978-11-30 1980-07-01 Litton Systems, Inc. System and method for regulating power output in a microwave oven
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JPH01195689A (en) 1989-08-07
EP0321767A3 (en) 1991-05-02
YU225288A (en) 1991-04-30
DE3743919C2 (en) 1989-10-05
KR890011484A (en) 1989-08-14
DE3743919A1 (en) 1989-07-13

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