EP0285781A1 - Procédé et dispositif pour créer des hautes températures - Google Patents

Procédé et dispositif pour créer des hautes températures Download PDF

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Publication number
EP0285781A1
EP0285781A1 EP19880102597 EP88102597A EP0285781A1 EP 0285781 A1 EP0285781 A1 EP 0285781A1 EP 19880102597 EP19880102597 EP 19880102597 EP 88102597 A EP88102597 A EP 88102597A EP 0285781 A1 EP0285781 A1 EP 0285781A1
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EP
European Patent Office
Prior art keywords
chamber
frequency waves
wall
temperature
housing
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.)
Withdrawn
Application number
EP19880102597
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German (de)
English (en)
Inventor
Horst Linn
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Individual
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Individual
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Publication date
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Publication of EP0285781A1 publication Critical patent/EP0285781A1/fr
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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

Definitions

  • the invention relates to a method for generating high temperatures with the features specified in the preamble of claim 1.
  • the invention further relates to a device for performing this method with the features specified in the preamble of claim 4.
  • a method and a device of the type mentioned at the outset are known from DE 29 21 955 A1.
  • the contents can be heated not only by means of microwaves but also with the aid of another heating device, which in the case described is radiation heating elements within the oven muffle.
  • the additional radiant heating elements have the purpose, for example, of browning food, which would not be the case when cooking food if only microwave was used.
  • the combination of microwave and radiant heating offers the advantage that particularly short cooking times can be achieved.
  • the oven muffle or chamber is surrounded by thermal insulation, the purpose of which is to prevent radiation of heat to the outside and, in particular, to counteract heating of the microwave generator arranged above the oven muffle or chamber. The heat insulation should therefore remain as cold as possible.
  • the actual chamber wall consists of a material that cannot be excited by microwaves.
  • the microwaves are introduced into the chamber via a waveguide. Due to the construction, the known microwave heating device is in no way suitable for reaching particularly high temperatures. The highest temperatures mentioned are 500 ° C for self-cleaning purposes.
  • temperatures below 1000 ° C there are a number of materials that can withstand heating, even in an oxygen-containing atmosphere, without damage, e.g. Graphite, SiC, but also a number of metals or metal alloys. However, temperatures below 1000 ° C are not always sufficient.
  • high-frequency waves in particular microwaves
  • microwaves are used to generate the comparatively high temperatures.
  • no complex measures are required to adapt the heating to the chamber.
  • the use of high-frequency waves, preferably microwaves offers the advantage that it can be used to heat bodies of any shape and thus also any walls of the chamber.
  • the walls of the chamber do not have to consist entirely of the material that can be excited by high-frequency waves. This material could also be used only in certain areas, for example in the form of profile elements embedded in the chamber walls, or as an additive, e.g. in powder form, for wall material.
  • a material is used for the chamber wall or parts of the wall that cannot be excited at room temperature by high-frequency waves, but - for example due to a phase transition - responds to high-frequency waves, in particular microwaves, from a certain temperature, the response temperature, and consequently when exposed to a high-frequency field is heated.
  • high-frequency waves in particular microwaves
  • the response temperature of the wall material for the chamber should be significantly higher than room temperature, this generally means that the response temperature is at least 1000 ° C.
  • a microwave oven is known from DE 35 35 532 A1, in which an additional heating element is provided, which can be brought into different positions.
  • the microwave heating and the additional heating can be operated independently of one another.
  • the adjustability of the additional heating element has the purpose of ensuring a desired special browning of the food to be cooked in the microwave oven.
  • DE 31 50 619 A1 describes a method and device for heating substances by microwaves, in which heat is generated as a result of absorption of microwave energy in a flat ferrite body, which is described in a metal body of the mass to be heated, which is connected flat to the ferrite body Case food, is fed. It is there that the mass to be heated is not heated directly by the action of the microwave energy on the mass, but via the detour of heating a carrier for the mass by microwave energy.
  • This document can not be found in the direction of the invention, namely to use a material to achieve the actual high operating temperature, which only couples high-frequency waves above certain temperatures, an additional heater being provided to achieve the response temperature.
  • the preferred device for carrying out the method has a very simple structure, as need not be explained in more detail.
  • it can be one of the commercial microwave ovens act, in which, surrounded by a corresponding heat-insulating layer, a chamber is arranged from wall material which responds to high-frequency waves at high temperature, this chamber being accessible via a door or flap in order to be able to insert the goods to be heated .
  • at least one "heating" insert or other heating device must then be provided, which are connected to a suitable, generally very simple mechanism for moving out of the zone of the high-frequency waves when the response temperature is reached.
  • Any gas inlets or outlets or temperature-resistant gas-tight devices are not required, but can be provided in order to also enable work in a vacuum or under protective gas. However, air can be used as the surrounding atmosphere without any problems. It is also easily possible to introduce into the chamber an inner chamber which is either filled with protective gas or through which protective gas can flow, for example a tube made of quartz glass.
  • All known devices can be used as the high-frequency radiation source. It is favorable, for example, if a magnetron covering the entire area of the chamber is provided as the radiation source. Such magnetrons are commercially available and are therefore available at comparatively low costs.
  • the at least one insert part In order to achieve the shortest possible movement paths for the at least one insert part, it is expedient to arrange it movably transversely to the main radiation direction of the radiation source for adjustment between the starting position and the operating position.
  • One will advantageously proceed in such a way that the at least one insert part can be moved into and out of the chamber on the side opposite the door or flap.
  • the housing is provided with at least one opening which allows the at least one insert part to be passed through and which is associated with a shield for the high-frequency waves, the at least one insert part can be moved into and out of the chamber, without it being necessary to open the door or flap, which can be dangerous since the temperature in the chamber is relatively high even when the at least one insert part is removed.
  • the at least one insert part can be designed differently.
  • Insert part is provided an approximately tubular, in cross-section adapted to the cross-section of the chamber, which is movable along its longitudinal axis parallel to an axis of symmetry of the chamber relative to the chamber.
  • Such a tubular insert part will be used if the chamber is also essentially tubular.
  • proper holding and guiding of the part must be ensured in order to prevent any damage to the insert part during its movement relative to the chamber.
  • rod-shaped insert parts In a large number of cases, it therefore appears more expedient if there is no tubular insert part but at least one rod-shaped insert part which is longitudinally displaceable between the approach position and the operating position, it usually being favorable if a plurality of rod-shaped insert parts arranged parallel to one another are provided.
  • the use of rod-shaped insert parts has the advantage that they can often be manufactured much more easily than a tubular part.
  • the small diameter and the simple design, which, for example, accommodate production from graphite or SiC, are particularly important.
  • rod-shaped insert parts have the advantage that the openings for moving in and out can be kept small, which facilitates the shielding of the passage openings.
  • rod-shaped insert parts are cheaper than a single tubular insert part because the individual rod-shaped insert parts are exactly there can arrange where a strong heating of the chamber wall is desired.
  • a holder for the mass to be heated can be attached more easily.
  • rod-shaped insert parts When using rod-shaped insert parts, it is expedient if they are arranged such that their respective distances from the wall of the chamber in the approach position are approximately the same, with the insert parts in the approach position also expediently being distributed approximately uniformly over the wall regions of the chamber parallel to their longitudinal axis should be.
  • the openings for the rod-shaped insert parts are formed by openings corresponding to these in cross-section, to which pipe sections adapted as a shield in cross-section connect to the insert parts, with respect to their diameter and their length are dimensioned such that passage of the high-frequency waves is prevented.
  • proper shielding against emerging high-frequency waves is always achieved by means of an appropriately dimensioned waveguide, without it being necessary to provide any movable shielding elements, etc.
  • the at least one insert part is attached to a carrier, preferably made of material which cannot be excited by high-frequency waves, which is used for the connection with a drive device arranged outside the shielding housing, for example a motor or pneumatic actuator, but also a manually operated mechanism.
  • a carrier preferably made of material which cannot be excited by high-frequency waves, which is used for the connection with a drive device arranged outside the shielding housing, for example a motor or pneumatic actuator, but also a manually operated mechanism.
  • the chamber is tubular and has at least one recess on its one end face for introducing at least one insert part, while the other end face of the chamber is up to the door or flap of the Housing is enough.
  • This design also has the advantage that access to the chamber is facilitated by the direct connection of the door or flap to the chamber and thus the introduction or removal of a sample is simplified.
  • a chamber designed in this way can also be easily set up for a gas-tight seal for operation under vacuum or under protective gas.
  • the door or flap can - as is known per se - be provided with a viewing window made of a material shielding against high-frequency waves.
  • the microwave oven which is shown very schematically in the drawing, comprises, as is customary in microwave devices, a housing 1 which forms a shield against the high-frequency radiation, for example a largely closed sheet metal housing.
  • a high-frequency radiation source 2 e.g. a magnetron for generating microwaves.
  • the radiation source 2 comprises separately controllable radiation sources 3a, 3b, 3c, e.g. only one separate resonator must be present, each of which is individually coupled to a common corresponding high-frequency generator.
  • a chamber 4 which is intended to receive the sample 5 to be heated.
  • a support 6 is arranged in the chamber, which expediently consists of a material which is resistant to high temperatures but does not respond to high-frequency waves, for example a ceramic or a ceramic substitute.
  • the chamber wall 7 is formed entirely of a material which is resistant even at very high temperatures, for example temperatures above 2000 ° C., ie in particular in oxygen-containing atmosphere not oxidized. Furthermore, it is a material which, when a response temperature of, for example, 1100 ° C. has been reached, absorbs high-frequency energy, ie can be heated by high-frequency waves, while it does not respond to high-frequency waves at this temperature.
  • a particularly suitable material for this is ZrO2 stabilized with CaO, in which ZrO2 undergoes a phase change at about 1100 ° C., as mentioned above.
  • a thick layer 8 of a heat insulating material which, however, must be selected such that it is not excited by high frequency waves, i.e. does not heat up when high-frequency energy is applied to the interior of the housing 1.
  • This layer 8 consists e.g. from several ceramic layers 8a, 8b, 8c.
  • the chamber 4 is rectangular in cross-section and arranged in such a way that its front edge directly connects to a door or flap 9, by means of which the housing 1 can be closed on the right-hand side in FIGS. 2 and 3.
  • the door 9 must of course shield high-frequency waves and should also be thermally insulated to protect the people working with the furnace according to the invention and to reduce energy consumption.
  • the door 9 is provided with a sight glass 10 through which the sample 5 can be observed during the heating.
  • the sight glass 10 must of course also be such that it shields the high-frequency radiation generated in the housing 1.
  • Corresponding glasses are known, for example, from the usual microwave ovens.
  • modified glasses which are stable even at correspondingly high temperatures, or to use a multilayer glass, for example a sight glass which is made on the inside instead of a single-layer glass for the sight glass 10 Quartz is made, while another pane is arranged on the outside of the door to shield the high-frequency radiation.
  • a multilayer glass for example a sight glass which is made on the inside instead of a single-layer glass for the sight glass 10 Quartz is made, while another pane is arranged on the outside of the door to shield the high-frequency radiation.
  • an attachment part 11 On the side of the housing 1 opposite the door 9, an attachment part 11 is provided, in which there are drive elements 12, for example a servomotor, a rack and pinion, etc., by means of which rod-shaped insert parts 13 are inserted into the chamber 4 from the side opposite the door 9 or can be moved out of this.
  • the drive elements are formed by a frame 14 which is substantially horizontal, i.e. horizontal, along an upper and lower guide 15. is movable parallel to the plane of symmetry of the chamber 4.
  • the rod-shaped insert parts 13 are fastened to the frame 14 by means of supports 16, which also have the form of rods.
  • the insert parts 13 consist of a material which can be excited or heated by high-frequency waves even at room temperature, but only up to a temperature against the influence of oxygen is stable, which is slightly above the temperature at which the material used for the wall 7 of the chamber 4 begins to absorb high-frequency energy.
  • the carriers 16 expediently consist of a material which - regardless of the respective temperature - does not absorb any high-frequency energy.
  • the carriers 16 are expediently made of a corresponding ceramic, which additionally has the advantage that, under certain circumstances, good thermal insulation can be achieved between the insert parts 13 and the frame 14 of the drive elements.
  • FIGS. 2 and 3 show, there must be a possibility that allows the rod-shaped insert parts 13 to be pushed in and out of the housing 1.
  • These openings 18 are each followed by a tubular extension 19, the internal dimensions of which correspond to the cross section of the openings 18.
  • the tubular lugs 19 act as a waveguide and are dimensioned or matched with respect to their length and their diameter such that high-frequency waves entering the housing end cannot exit into the attachment part 11.
  • FIG. 1 shows that the number and arrangement of the rod-shaped insert parts 13 can be chosen as desired. It is expedient, however, if the insert parts 13, as can be seen in FIG. 1, are arranged at approximately the same distance from one another and from the wall of the chamber 7 when they are in the starting position within the chamber 4. In addition, the distance between the insert parts 13 and the wall 7 of the chamber 4 should be as small as possible, in order not to have to accept any energy losses when heating the wall 7 of the chamber 4 through the insert parts 13.
  • the insert parts 13 do not necessarily have to be rod-shaped.
  • Another design is easily possible.
  • the chambers it would be conceivable to design the chambers to be tubular in cross-section, in which case it would be best to provide only one tubular insert, the cross-section of which is adapted to the cross-section of the chamber and in the heating position close to the inside of the wall 7 the chamber.
  • the drive device 12 would then also have to be designed differently.
  • shielding by pipe sockets would hardly be possible.
  • the sample 5 is placed on the support 6 in the chamber 4.
  • the insert parts 13 are brought by means of the drive device 12 into the advanced starting position shown in FIG. 2, in which the rod-shaped insert parts 13 are arranged approximately uniformly distributed along the wall 7 of the chamber 4.
  • the high-frequency radiation source 2 is then switched on.
  • the insert parts 13 are excited and heated to a temperature which is far above room temperature, generally around 1100 ° C.
  • the insert parts 13 in turn heat the adjacent portions of the wall 7 of the chamber 4 by radiation, until the temperature of the wall 7 of the chamber 4, at least in the areas adjacent to the insert parts 13, is so high that the material of the Wall 7 of the chamber 4 can be excited by radio frequency energy.
  • this temperature is about 1100 ° C, because at this temperature a phase transformation of the ZrO2 takes place.
  • the insertion of the insert parts 13 from the chamber 4 can e.g. take place automatically by the temperature in the chamber 4 being measured and the drive device 12 being controlled as a function of the temperature.
  • the radiation source 2 remains switched on as long as the sample 5 is to be heated or until the sample 5 has reached the desired temperature. It is important that sample 5 is usually heated in normal air, i.e. in an oxidizing atmosphere. This was only possible in the previously known ovens under very special circumstances, especially after taking special protective measures for the heating winding, etc. In the present case, such heating can take place without there being any risk of damage to the heating element in the form of the wall 7 of the chamber 4.
  • the radiation source 2 can be switched off.
  • the wall 7 of the chamber 4 then cools down, the cooling optionally being accelerated in a simple manner by blowing air into the chamber 4.
  • the wall 7 of the chamber 4 would have to be divided according to the arrangement of the zones of the radiation source 2.
  • the energy emitted by the high-frequency radiation source is also easy, e.g. Adapt to the respective needs via pulse operation or by means of appropriate power control.
  • the heating of the chamber wall to the response temperature can be carried out not only by means of the insert parts which can be coupled to high frequency, but also with the aid of other heating devices, e.g. Resistance or inductive heating (if there are inductively heated parts available).

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Constitution Of High-Frequency Heating (AREA)
EP19880102597 1987-02-27 1988-02-23 Procédé et dispositif pour créer des hautes températures Withdrawn EP0285781A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19873706336 DE3706336C1 (de) 1987-02-27 1987-02-27 Verfahren und Vorrichtung zur Erzeugung hoher Temperaturen
DE3706336 1987-02-27

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EP0285781A1 true EP0285781A1 (fr) 1988-10-12

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EP19880102597 Withdrawn EP0285781A1 (fr) 1987-02-27 1988-02-23 Procédé et dispositif pour créer des hautes températures

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993016571A1 (fr) * 1992-02-07 1993-08-19 Electricity Association Technology Limited Traitement de materiaux par micro-ondes
WO1998016965A1 (fr) * 1996-10-16 1998-04-23 Widia Gmbh Four a micro-ondes et elements constitutifs appropries

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3936267C2 (de) * 1989-10-31 1997-12-11 Werner Lautenschlaeger Einsatzteil für einen Mikrowellenofen
GB9021707D0 (en) * 1990-10-05 1990-11-21 Gribby Steven T Water heaters
DE19648366C1 (de) * 1996-11-22 1998-04-02 Riedhammer Gmbh Co Kg Anlage zur thermischen Behandlung von Produkten
DE19654356C2 (de) * 1996-12-24 2002-06-13 Ind Ofenbau Rudolf Brands Gmbh Ofen zur Hochtemperatur-Wärmebehandlung

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2522934A1 (de) * 1974-05-24 1975-12-04 Sharp Kk Hochfrequenzherd mit braeunungseinheit
DE2462853B1 (de) * 1973-10-25 1979-12-20 Raytheon Co Mikrowellen-Erhitzungseinrichtung
DE3150619A1 (de) * 1980-12-29 1982-08-12 Raytheon Co., 02173 Lexington, Mass. Verfahren und geraet zur erhitzung von stoffen, insbesondere von nahrungsmitteln, durch mikrowellen
DE3139268A1 (de) * 1981-10-02 1983-04-21 geb. Görts Ingrid Drübenbach Mit hoechstfrequenzen betriebene vorrichtung zur erwaermung von fluessigkeiten
US4398077A (en) * 1980-10-06 1983-08-09 Raytheon Company Microwave cooking utensil
DE3308732A1 (de) * 1982-03-11 1983-09-22 Bosch-Siemens Hausgeräte GmbH, 7000 Stuttgart Hochfrequnezheizgeraet mit einer rotierenden antenne
DE3535532A1 (de) * 1984-10-05 1986-04-30 Sharp Kk Heizgeraet mit waehlbarer position des heizelementes

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2921955C2 (de) * 1979-05-30 1982-06-09 M.A.N.- Roland Druckmaschinen AG, 6050 Offenbach Bogenanleger für eine Bogendruckmaschine

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2462853B1 (de) * 1973-10-25 1979-12-20 Raytheon Co Mikrowellen-Erhitzungseinrichtung
DE2522934A1 (de) * 1974-05-24 1975-12-04 Sharp Kk Hochfrequenzherd mit braeunungseinheit
US4398077A (en) * 1980-10-06 1983-08-09 Raytheon Company Microwave cooking utensil
DE3150619A1 (de) * 1980-12-29 1982-08-12 Raytheon Co., 02173 Lexington, Mass. Verfahren und geraet zur erhitzung von stoffen, insbesondere von nahrungsmitteln, durch mikrowellen
DE3139268A1 (de) * 1981-10-02 1983-04-21 geb. Görts Ingrid Drübenbach Mit hoechstfrequenzen betriebene vorrichtung zur erwaermung von fluessigkeiten
DE3308732A1 (de) * 1982-03-11 1983-09-22 Bosch-Siemens Hausgeräte GmbH, 7000 Stuttgart Hochfrequnezheizgeraet mit einer rotierenden antenne
DE3535532A1 (de) * 1984-10-05 1986-04-30 Sharp Kk Heizgeraet mit waehlbarer position des heizelementes

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993016571A1 (fr) * 1992-02-07 1993-08-19 Electricity Association Technology Limited Traitement de materiaux par micro-ondes
WO1998016965A1 (fr) * 1996-10-16 1998-04-23 Widia Gmbh Four a micro-ondes et elements constitutifs appropries

Also Published As

Publication number Publication date
DE3706336C1 (de) 1988-04-28

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