EP0457948B1 - Dispositif à micro-ondes - Google Patents

Dispositif à micro-ondes Download PDF

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Publication number
EP0457948B1
EP0457948B1 EP19900109863 EP90109863A EP0457948B1 EP 0457948 B1 EP0457948 B1 EP 0457948B1 EP 19900109863 EP19900109863 EP 19900109863 EP 90109863 A EP90109863 A EP 90109863A EP 0457948 B1 EP0457948 B1 EP 0457948B1
Authority
EP
European Patent Office
Prior art keywords
chamber
microwave
movable
wall
resonator
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.)
Expired - Lifetime
Application number
EP19900109863
Other languages
German (de)
English (en)
Other versions
EP0457948A1 (fr
Inventor
Lothar Dr. Schuh
Friedrich Dr. Harbach
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.)
ABB Patent GmbH
Original Assignee
ABB Patent GmbH
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 ABB Patent GmbH filed Critical ABB Patent GmbH
Priority to DE90109863T priority Critical patent/DE59004441D1/de
Priority to EP19900109863 priority patent/EP0457948B1/fr
Publication of EP0457948A1 publication Critical patent/EP0457948A1/fr
Application granted granted Critical
Publication of EP0457948B1 publication Critical patent/EP0457948B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • H05B6/80—Apparatus for specific applications

Definitions

  • Microwave devices with a multimode chamber with at least one movable resonator wall are shown in FIGS. 2 and 3 of GB-A-926 958 and described in the associated description part.
  • the movable wall is designed as a reflector of an infrared radiator that bounces around a pivot point at a small angle.
  • the rocking movement results in an oscillating movement of wave maxima in the resonator chamber.
  • the resonator volume practically does not change, so that the number of modes remains constant. There is only a slight change in the field distribution.
  • DE-B 11 86 570 shows a microwave device which does not have a multimode resonator for receiving a workpiece, but rather a slot radiator through which a workpiece to be heated is passed.
  • the slot radiator is the exit opening of a waveguide into which a magnetron feeds.
  • the waveguide is to be regarded as a single-mode chamber.
  • the field strength maximum of the radiation characteristic at the outlet opening moves back and forth. This is achieved by a movable short-circuit slide in the waveguide.
  • DE-B 24 62 853 discloses a microwave device with a plurality of microwave generators for providing the microwave energy. Given the dimensions of the chamber acting as a resonator and an operating frequency of a few GHz, standing waves are formed. For example, the usual operating frequency of 2.45 GHz corresponds to a free space wavelength of approximately 12 cm. The resulting stationary wave nodes and wave bellies cause disturbing field inhomogeneities, which lead to the fact that, for example, larger ceramic components are heated differently locally and sinter inhomogeneously. This leads to unusable workpieces or even to their complete destruction.
  • the invention is based on the object of specifying a microwave device which has a highly homogeneous field distribution during a heating or sintering process in the volume of a workpiece.
  • the resonator can preferably be designed with chamber walls arranged parallel to one another, of which one chamber wall is designed to be movable and can be set in repetitive lifting movements.
  • curved walls can also be provided to achieve special field configurations.
  • cylindrical resonators or resonators with hollow mirror-shaped walls are possible.
  • the microwave device according to the invention has the advantage that the microwave field is homogenized, so that even complex-shaped parts can be heated homogeneously.
  • the sintered material is not set in motion.
  • a single waveguide can be used with the interposition of a circulator. This will have no effect on the generators.
  • the invention proposes to have at least one resonator wall perform a movement, preferably a stroke movement, with a low frequency, that is to say to allow it to vibrate.
  • a movement preferably a stroke movement
  • a low frequency that is to say to allow it to vibrate.
  • a wall is designed to be adjustable so that the desired wave propagation (resonance) can be set before the heating process is carried out (see Ceramic Bulletin, page 1603, paragraph 2 and page 1604, paragraph 2).
  • the movable wall of the single-mode chamber is therefore only intended for adjustment, ie. for setting the location of the maximum power of the standing wave in the chamber.
  • the chamber wall movement according to the invention a field distribution which is more homogeneous on average over time than can be achieved with known measures, for example rotary blades.
  • the characteristic of the standing waves is influenced to a large extent by the position of the chamber walls.
  • a contactless lambda quarter short-circuit structure ensures that the chamber wall can be moved without friction and that no microwave radiation can escape through leaks.
  • the device can be operated with both continuous and pulsed microwave energy.
  • the pulse frequency and pulse shape can run synchronized with the wall movement as well as being stochastic.
  • a variable or fixed stroke frequency in the range from 0.1 to 100 Hz and a stroke amplitude in the range from approximately 0.5 to 20 cm are preferred for the wall movement.
  • the drawing shows schematically the structure of a microwave device according to the invention.
  • the device contains a metallic chamber 1 made, for example, of stainless steel, which has fixed walls 2 and a movable wall 3.
  • the dimensions of the chamber are approximately 60 x 60 x 60 cm3.
  • the movable wall 3 is coupled to a controllable reciprocating piston engine 5 via a push rod 4.
  • the rod 4 is supported by a ball bearing 6.
  • a gap 7 is expedient between the movable wall 3 and the fixed walls 2, which is approximately 1 to 2 mm wide.
  • the edge of the movable wall 3 is designed as a quarter-wave short-circuit slide 8.
  • a high-frequency insulation ring 10 can be attached to the part 9 of the lambda quarter short-circuit slide 8 that is turned toward the outside.
  • a high-frequency insulation ring 10 can be designed, for example, as a plastic ring or as a brush with microwave-absorbing properties.
  • This additional safety device has no mechanical guiding or supporting function, so that even when this safety device is used, there is a practically contactless movement of the movable wall 3 in the chamber 1.
  • a second quarter-wave short-circuit slide 11 is arranged on the push rod 4.
  • a microwave-impermeable metal grille 12 with a corresponding mesh size and a stable pipe duct 13 for the push rod 4 is provided for shielding on the chamber 1 in front of the movable wall 3.
  • the existing structural parts for moving and guiding the movable wall 3, such as rod 4, ball bearing 6 and bushing 13, must be made sufficiently stable to ensure a constant narrow gap 7 during wall movement.
  • a ventilation channel 14 is installed in one of the fixed walls 2, the diameter-length ratio of which is approximately 1: 3.
  • the opening of the ventilation channel 14 is secured by a metallic ventilation grille 15 against the escape of microwave radiation.
  • a ceramic molded body 16 to be sintered is arranged within the chamber 1 in a microwave-transparent container 17.
  • the molded body 16 is surrounded by heat-insulating and microwave-transparent fiber mats 18, which consist, for example, of aluminum oxide ceramic.
  • the movable wall 3 is set in a repetitive lifting movement and microwave energy is fed in via the waveguide 25.
  • the standing waves caused by the chamber dimensions and the interferences given by several modes are continuously changed. It creates other waveforms, which results in a spatially and temporally changing plurality of power maxima, which leads to homogeneous heating of the molded body 16.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Constitution Of High-Frequency Heating (AREA)

Claims (1)

  1. Dispositif à micro-ondes comportant une chambre multimodes (1) formée de plusieurs parois de chambre (2, 3) métalliques qui agissent comme résonateurs, dans laquelle une pièce (16) à réchauffer peut être placée et dans laquelle de l'énergie à micro-ondes peut être introduite,
    a) avec au moins une paroi de chambre (3) agencée de manière mobile et
    b) avec des moyens (4, 5, 22) grâce auxquels la paroi de chambre (3) mobile peut être déplacée suivant un mouvement répétitif pendant le fonctionnement du dispositif à micro-ondes,
    caractérisé par le fait
    c) qu'il est prévu des moyens (7 à 10) destinés à assurer l'étanchéité aux fréquences élevées de la paroi de chambre (3) mobile par rapport aux parois de chambre (2) fixes, de telle sorte que le volume du résonateur varie lorsque la paroi mobile (3) se déplace.
EP19900109863 1990-05-23 1990-05-23 Dispositif à micro-ondes Expired - Lifetime EP0457948B1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE90109863T DE59004441D1 (de) 1990-05-23 1990-05-23 Mikrowelleneinrichtung.
EP19900109863 EP0457948B1 (fr) 1990-05-23 1990-05-23 Dispositif à micro-ondes

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19900109863 EP0457948B1 (fr) 1990-05-23 1990-05-23 Dispositif à micro-ondes

Publications (2)

Publication Number Publication Date
EP0457948A1 EP0457948A1 (fr) 1991-11-27
EP0457948B1 true EP0457948B1 (fr) 1994-01-26

Family

ID=8204023

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900109863 Expired - Lifetime EP0457948B1 (fr) 1990-05-23 1990-05-23 Dispositif à micro-ondes

Country Status (2)

Country Link
EP (1) EP0457948B1 (fr)
DE (1) DE59004441D1 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2627730B2 (ja) * 1993-09-23 1997-07-09 エルジー電子株式会社 電子レンジの自動整合装置
DE19700140A1 (de) * 1997-01-04 1998-07-09 Gero Hochtemperaturoefen Gmbh Brennofen für die Hochtemperaturbehandlung von Materialien mit niedrigem dielektrischem Verlustfaktor
MY123981A (en) * 1997-08-26 2006-06-30 Samsung Electronics Co Ltd Microwave oven having a cooking chamber reflecting microwaves at varying angles
IT1304897B1 (it) * 1998-09-08 2001-04-05 Gaudenzio Borelli Forno a microonde per la cottura di materiale ceramico sotto pressione
DE102006052169A1 (de) * 2006-11-02 2008-05-08 Ivan Dr. Imenokhoyev Mikrowelleneinrichtung zur Erwärmung

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB926958A (en) * 1957-12-10 1963-05-22 Miwag Mikrowellen A G Improvements in apparatus for heating substances and objects by means of micro-waves
DE1186570B (de) * 1958-10-01 1965-02-04 Robert Bosch Elektronik Ges Mi Schlitzstrahler fuer die Erwaermung von dielektrischen Stoffen
FR2053592A5 (en) * 1969-07-10 1971-04-16 Kriz Francois Rotary plastisol moulding device
FR2315986A1 (fr) * 1975-07-04 1977-01-28 Olivier Jean Procede et reacteur resonant pour traiter une matiere par des ondes electromagnetiques
US4054768A (en) * 1976-08-06 1977-10-18 White Donald A System for increasing visibility and microwave distribution within a microwave oven
US4361744A (en) * 1981-01-12 1982-11-30 Despatch Industries, Inc. Microwave process unit

Also Published As

Publication number Publication date
EP0457948A1 (fr) 1991-11-27
DE59004441D1 (de) 1994-03-10

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