EP0457948A1 - Dispositif à micro-ondes - Google Patents

Dispositif à micro-ondes Download PDF

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Publication number
EP0457948A1
EP0457948A1 EP90109863A EP90109863A EP0457948A1 EP 0457948 A1 EP0457948 A1 EP 0457948A1 EP 90109863 A EP90109863 A EP 90109863A EP 90109863 A EP90109863 A EP 90109863A EP 0457948 A1 EP0457948 A1 EP 0457948A1
Authority
EP
European Patent Office
Prior art keywords
chamber
microwave device
microwave
movement
wall
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.)
Granted
Application number
EP90109863A
Other languages
German (de)
English (en)
Other versions
EP0457948B1 (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

  • the invention relates to a microwave device according to the preamble of claim 1.
  • the microwave device is provided for rapid and homogeneous heating and for sintering ceramic components.
  • a microwave device with a relatively large oven chamber and a high microwave power is required.
  • Such a microwave device is known from DE-AS 24 62 853 (publication D1), several microwave generators being provided to provide the microwave energy.
  • standing waves are formed.
  • 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 cause that, for example, larger ceramic components are heated locally differently and sinter inhomogeneously. This leads to unusable workpieces or even to their complete destruction.
  • a remedial measure known from household microwave devices namely a rotating reflector wing
  • D1 A remedial measure known from household microwave devices, namely a rotating reflector wing
  • the effectiveness of the rotary wing which is said to cause a continuous change in the field distribution, is unsatisfactory.
  • turntables or other devices are more effective which cause a change in the location of a sintered material to be heated within the chamber. Since sintered goods are sensitive to vibrations, as mentioned in the D1, turntable arrangements which cause vibrations are also not very suitable.
  • the invention is therefore based on the object of specifying a microwave heating device which avoids the disadvantages of known devices.
  • a microwave device with a metallic multimode chamber as a resonator which preferably has chamber walls arranged parallel to one another, and into which microwave energy is fed, means being provided which cause at least one of the chamber walls to be able to be set in repetitive stroke movements during operation , whereby there is a periodic change in the resonator dimensions and thus the reflection conditions and the resonance conditions.
  • a microwave device with a metallic multimode chamber as a resonator which preferably has chamber walls arranged parallel to one another, and into which microwave energy is fed, means being provided which cause at least one of the chamber walls to be able to be set in repetitive stroke movements during operation , whereby there is a periodic change in the resonator dimensions and thus the reflection conditions and the resonance conditions.
  • curved walls can also be provided in order 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 adjustable to the desired wave propagation (resonance) before To be able to stop the heating process (see D2, 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.
  • a suggestion in the case of a multimode chamber by repetitive movement of a chamber wall to bring about a change in the field distribution during the heating process cannot be found in document 2.
  • the chamber wall movement according to the invention a field distribution which is more homogeneous on average than with known measures, e.g. Rotary wings, can be achieved.
  • the characteristic of the standing waves is influenced to a large extent by the position of the chamber walls.
  • With a contactless lambda quarter short-circuit structure it is achieved 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 between the movable wall 3 and the fixed walls 2 is expedient, 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 quarter-wave 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 leadthrough 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 leadthrough 13, must be made sufficiently stable to ensure a consistently 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 inside 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.
  • a measuring head 19 of a high-temperature thermometer is arranged on the surface of the molded body 16 and is connected to a control and regulating device 22 for microwave generators 23 via a light guide 20 and a bushing 21 in the chamber 1.
  • the microwave energy possibly fed into the chamber 1 via the circulators 24 and the waveguide 25 is controlled while avoiding inadmissible temperatures or temperature gradients in accordance with predetermined temperature-time profiles.
  • the microwave power is typically several kilowatts.
  • 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 caused 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 a homogeneous heating of the molded body 16.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Constitution Of High-Frequency Heating (AREA)
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 true EP0457948A1 (fr) 1991-11-27
EP0457948B1 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)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5512736A (en) * 1993-09-23 1996-04-30 Goldstar Co., Ltd. Auto-load impedance matching device of a microwave oven
WO1998030067A1 (fr) * 1997-01-04 1998-07-09 Gero Hochtemperaturöfen Gmbh Four pour le traitement a haute temperature de materiaux a faible facteur de perte dielectrique
GB2329816A (en) * 1997-08-26 1999-03-31 Samsung Electronics Co Ltd Microwave oven with rectilinearly movable reflector
EP0985893A1 (fr) * 1998-09-08 2000-03-15 Gaudenzio Borelli Four à micro-ondes pour cuire sous pression des matériaux céramiques
DE102006052169A1 (de) * 2006-11-02 2008-05-08 Ivan Dr. Imenokhoyev Mikrowelleneinrichtung zur Erwärmung

Citations (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

Patent Citations (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

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
JOURNAL OF PHYSICS E. SCIENTIFIC INSTRUMENTS. vol. 9, no. 5, Mai 1976, ISHING, BRISTOL GB & S. Weiss: "T-jump apparatus with microwave heating" *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5512736A (en) * 1993-09-23 1996-04-30 Goldstar Co., Ltd. Auto-load impedance matching device of a microwave oven
WO1998030067A1 (fr) * 1997-01-04 1998-07-09 Gero Hochtemperaturöfen Gmbh Four pour le traitement a haute temperature de materiaux a faible facteur de perte dielectrique
GB2329816A (en) * 1997-08-26 1999-03-31 Samsung Electronics Co Ltd Microwave oven with rectilinearly movable reflector
GB2329816B (en) * 1997-08-26 1999-08-18 Samsung Electronics Co Ltd Microwave oven with moveable reflector
US5998775A (en) * 1997-08-26 1999-12-07 Samsung Electronics Co., Ltd. Microwave oven having a cooking chamber reflecting microwaves at varying angles
EP0985893A1 (fr) * 1998-09-08 2000-03-15 Gaudenzio Borelli Four à micro-ondes pour cuire sous pression des matériaux céramiques
DE102006052169A1 (de) * 2006-11-02 2008-05-08 Ivan Dr. Imenokhoyev Mikrowelleneinrichtung zur Erwärmung

Also Published As

Publication number Publication date
EP0457948B1 (fr) 1994-01-26
DE59004441D1 (de) 1994-03-10

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