US3909574A - Microwave tunnel-ovens - Google Patents

Microwave tunnel-ovens Download PDF

Info

Publication number
US3909574A
US3909574A US455538A US45553874A US3909574A US 3909574 A US3909574 A US 3909574A US 455538 A US455538 A US 455538A US 45553874 A US45553874 A US 45553874A US 3909574 A US3909574 A US 3909574A
Authority
US
United States
Prior art keywords
tunnel
lining
members
oven
ferrite
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
US455538A
Other languages
English (en)
Inventor
Paul Curt Muller
Niklaus Kehl
Egon Kreis
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.)
Kreis AG
Original Assignee
Kreis AG
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 Kreis AG filed Critical Kreis AG
Application granted granted Critical
Publication of US3909574A publication Critical patent/US3909574A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • H05B6/78—Arrangements for continuous movement of material
    • 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
    • H05B6/76—Prevention of microwave leakage, e.g. door sealings

Definitions

  • ABSTRACT relates to microwave tunnel ovens of [30] Foreign Application Priority Data the kind havingabsorption sections enclosed by a A H 1973 s Ind 5187/73 metal caslng which form cont1nuat1ons of a central zcr passage of said oven at both the inlet and outlet ends.
  • the invention consists in that said absorption sections '2 219/1055 Contain a plurality of load members, each of which is made of a microwave absorbem material and is up 9 [58] fg i ranged between said casing and said central opening 35 the said load members being spaced from one another.
  • load members may be individual ferrite rods or tubes or may consist of individual portions of a plas- [56]
  • References Clted tics material helical tube containing a liquid and ar- UNITED STATES PATENTS ranged around the central passage. 3,365,562 l/l968 Jeppson 1. 219/1055 A 3,475,827 11/1969 Goerg 219 1055 A 8 ClalmS, 2 Drawing Figures 3,564,187 2/1971 Smith 219/1055 A UHF COOLING 18 7 Sept. 30,1975
  • the present invention relates to microwave tunnelovens of the kind having microwave absorption sections enclosed by a metal casing which form continuations of a central passage of said oven at both the inlet and outlet ends.
  • microwave tunnelovens of the kind having microwave absorption sections enclosed by a metal casing which form continuations of a central passage of said oven at both the inlet and outlet ends.
  • ovens will be referred to as of the kind described.
  • microwave ovens have acquired a particular importance in connection with the heating of precooked food or the cooking of raw food due to the fact that'the time they take to cook or heat is orders of magnitude less than the time required with conventional methods of heating'or cooking where the direct application of thermal energy is employed.
  • microwaves are a powerful form of electromagnetic radiation which has no difficulty in passing through dielectrics and heat insulation and can even heat up people, since they are living creatures containing liquid.
  • microwave tunnel-ovens since this type of oven remains open at both the inlet and outlet ends even while in operation.
  • microwave tunnel-ovens of the kind described have absorption sections which consist in essence of a water jacket formed by a twin-walled tube, this jacket forming a continuation of the tunnel through the oven of some considerable length.
  • water is known to be capable of absorbing microwaves and heating up, that is to say it forms a load in the microwave field which consumes energy, it was possible by using waterjackets of this type to reduce the strength of any microwave field which could still be detected outside the oven to an acceptable level, despite the open-ended tunnel, the level in question being between approximately 1 and mW/cm depending on local government regulations.
  • a microwave tunneloven of the kind described includes a plurality of load members made of a material which is absorbent to microwaves which load members are arranged between the casing and the central passage in the absorption section, these members being arranged at a distance from one another.
  • the load members may be individual ferrite rods or tubes which may be arranged at a distance from one another transversely to the central passage. In this case satisfactory results can be achieved even with only one row of ferrite rods or tubes arranged in each of the side walls, floor and roof of the shielding.
  • the load members it is also possible for the load members to be formed by the individual turns of a plastics tube containing a liquid, e.g. water which forms a spiral around the central passage.
  • a liquid e.g. water which forms a spiral around the central passage.
  • FIG. 1 shows a simplified, perspective view of the inlet end of a first embodiment of the microwave tunnel-oven in which parts of the shielding at the inlet end are broken away, and
  • FIG. 2 shows a modification constituting a embodiment with different load members from those shown in the embodiment of FIG. 1.
  • a microwave tunneloven marked 10 in FIG. 1 has an oven section proper 11 which is subject to radiation and which is preceded at the inlet end by an absorption section 12. At the outlet end, oven section 11 is followed by a section (not shown) similar to absorption section 12.
  • oven section 11 has one or more UHF excitation apertures 13 which are used to connect up a wave-guide leading to a magnetron.
  • the wave guide and magnetron are not shown since per se they form no part of the invention and are moreover so well known in the art as not to require illustration.
  • the microwave radiation enters the central passage of the oven shown at 15, through the openings 13, as indicated by arrow 14.
  • the articles to be heated in the oven 10 are transported through it by any suitable means shown for example as a conveyor belt 16, which is therefore only shown diagrammatically, only the top run of the belt '16 passing through the central passage 15.
  • the absorption section 12 is delimited on the outside by a casing 17 of polished sheet-metal which is closed off at the inlet end by a screen (not shown) which leaves the central passage 15 free.
  • a casing 17 of polished sheet-metal which is closed off at the inlet end by a screen (not shown) which leaves the central passage 15 free.
  • the roof, side-walls and floor of the casing 17 each have secured to them, by means of screws 18, two longitudinally extending supporting ribs 19, to the inner longitudinal faces of which is secured, by means of further screws 20, the inner lining, which consists of plates 21.
  • Both the supporting ribs 19 and the plates 21 are made from a dielectric material such as polytetrafluorethylene, so that the material in question will not prevent leakage radiation from reaching the space between the plates 21 and the casing 17.
  • Each of the supporting ribs 19 contains a row of holes 22 each of which is used, as shown, to hold a load member 23 in the form of a ferrite rod or tube.
  • the ferrite rods being arranged in a grid-like structure which is mounted at a distance from the plates 21 and from the inside face of the casing 17.
  • the load members 23 are also arranged at a distance from one another.
  • the gap between the load members 23 and the inside face of the casing is filled with a layer 24 of a heat-insulating material such as an asbestos, fibreglass or mineral wool mat.
  • a layer 24 of a heat-insulating material such as an asbestos, fibreglass or mineral wool mat.
  • the high efficiency of the shielding described may be attributed to the fact that, when microwave radiation exists, the strength of the microwave field is reduced downstream of each of the load members 23.
  • the main part of the shielding action occurs as a result of the energy being absorbed in the ferrite rods and tubes and then in the water jacket. 7
  • the load members 23 It is important for the load members 23 to be spaced away from the inside wall of the casing 17 so that the field originating from the load members which counteracts the leakage field can be propagated practically without obstruction. Less critical is the gap between the load members and the outer face of the plates 21 and this may as small as desired provided that it is still possible for a stream of cooling air to flow through it.
  • FIG. 2 is shown a square-cornered, spirally wound plastics tube 26 which may be used in the absorption section 12 shown in FIG. 1 in place of the load members 23.
  • the individual segments 27, 28, 29 and 30 of the tube form the individual load members.
  • the plastics tube 26 is filled with water and its inlet 31 and outlet 32 are connected to a piping circuit 33 (shown by a broken line) in which are inserted a circulating pump 35 and a cooler 34.
  • the plastics tube 26 could also be connected to the main water-supply.
  • segments 27 to 30 could be arranged to lie directly against the plates 21 forming the lining and with this arrangement it is not then necessary for the heat due to energy loss to be removed in any special way.
  • a microwave tunnel-oven having absorption sections enclosed by a metal casisng forming continuations of a central passage of said oven at both the inlet and outlet ends of said oven, the improvement comprising said absorption sections including a plurality of individual elongated load members of a ferrite material for absorbing microwaves, said plurality of ferrite load members being arranged between said casing and said continuations of said central passage at a distance next to one another in spaced relationship transversely to said continuations of said central passage.
  • a tunnel-oven according to claim 1 including a lining surrounding said continuations of said central passage, which lining is composed of a dielectric material, and wherein said load members are arranged at a distance from said lining between said casing and said lining.
  • a tunnel-oven according to claim 2 wherein a layer of heat insulating material is arranged between said ferrite members and said metal casing, the spacing between said lining and said ferrite members being sufficient to allow a flow of cooling air to pass through said spacing.
  • a tunnel-oven according to claim 1 wherein said ferrite members are spaced apart by a distance approximately corresponding to their diameter.
  • a tunnel-oven according to claim I wherein additional load members are formed by individual portions of the turns of a tube which forms a spiral around said continuations of said central passage and is arranged to contain a liquid.
  • a tunnel-oven according to claim 6, including a lining of a dielectric material surrounding said continuations of said central passage, and wherein said additional load members lie directly against said lining and said plurality of ferrite load members are arranged between said additional load members and said casing.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Constitution Of High-Frequency Heating (AREA)
US455538A 1973-04-11 1974-03-28 Microwave tunnel-ovens Expired - Lifetime US3909574A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH518273A CH555516A (de) 1973-04-11 1973-04-11 Mikrowellen-tunnelofen.

Publications (1)

Publication Number Publication Date
US3909574A true US3909574A (en) 1975-09-30

Family

ID=4289289

Family Applications (1)

Application Number Title Priority Date Filing Date
US455538A Expired - Lifetime US3909574A (en) 1973-04-11 1974-03-28 Microwave tunnel-ovens

Country Status (9)

Country Link
US (1) US3909574A (de)
AT (1) AT326232B (de)
CA (1) CA999055A (de)
CH (1) CH555516A (de)
DE (1) DE2407927A1 (de)
GB (1) GB1461177A (de)
IT (1) IT1003673B (de)
NL (1) NL7403361A (de)
SE (1) SE393732B (de)

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2642152A1 (de) * 1975-10-09 1977-04-21 Nicolas Meisel Tunnelofen
US4045638A (en) * 1976-03-09 1977-08-30 Bing Chiang Continuous flow heat treating apparatus using microwaves
US4216727A (en) * 1978-05-22 1980-08-12 Plastics, Inc. Portable turntable for microwave oven
US4239009A (en) * 1979-08-29 1980-12-16 Plastics, Inc. Portable turntable for microwave oven
US4330696A (en) * 1978-04-17 1982-05-18 Plastics, Inc. Portable turntable for ovens
US4405850A (en) * 1978-10-06 1983-09-20 Raytheon Company Combination microwave heating apparatus
US4754111A (en) * 1980-03-18 1988-06-28 Plastics, Inc. Portable turntable for ovens
US4861955A (en) * 1987-07-09 1989-08-29 Shen Zhi Yuan Matched absorptive end choke for microwave applicators
US4886948A (en) * 1978-04-17 1989-12-12 Plastics, Inc. Portable turntable with shielded drive motor for microwave ovens
US4922731A (en) * 1988-09-30 1990-05-08 Texas Instruments Incorporated Quartz conductive baffles for heat removal and method
US5245149A (en) * 1990-06-21 1993-09-14 Immobiliare Centro Nord S.P.A. Process and device for accelerating the drying of cement mixes
US5523548A (en) * 1994-01-31 1996-06-04 Nec Corporation Electromagnetic wave heater having a cone-shaped container whose tapered portion is pointed and directed toward the electromagnetic wave generator
USRE36943E (en) * 1993-07-09 2000-11-07 Gamma-Metrics Modularized assembly for bulk material analyzer
US20030183623A1 (en) * 2002-03-29 2003-10-02 Fritts Rex E. Shielding system for protecting select portions of a food product during processing in a conveyorized microwave oven
US20070187401A1 (en) * 2003-10-22 2007-08-16 Sergio Quinta Microwaves blocker apparatus for opening microwaves oven
WO2014195450A1 (de) * 2013-06-07 2014-12-11 Dieffenbacher GmbH Maschinen- und Anlagenbau Anlage, mikrowellendurchlaufofen und verfahren zur kontinuierlichen herstellung von werkstoffen, bevorzugt von werkstoffplatten
US11412584B2 (en) 2017-12-08 2022-08-09 Alkar-Rapidpak, Inc. Ovens with metallic belts and microwave launch box assemblies for processing food products
US20220346198A1 (en) * 2021-04-26 2022-10-27 Alkar-Rapidpak, Inc. Food Processing Machines With Microwave Heating Systems And Microwave Suppression Systems

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3421778A1 (de) * 1984-06-12 1986-01-02 Karl Dr. 7800 Freiburg Fritz Mikrowellen-erwaermungsverfahren
DE102007043483B4 (de) * 2007-09-12 2009-07-09 Rational Ag Abdichtungsvorrichtung zum Verringern eines Mikrowellenaustrittes aus einem Gargerät und Gargerät mit zumindest einer solchen Abdichtungsvorrichtung

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3365562A (en) * 1962-12-17 1968-01-23 Cryodry Corp Apparatus and process for microwave treatment
US3475827A (en) * 1967-12-06 1969-11-04 Bechtel Int Corp R.f. seal in microwave drier
US3564187A (en) * 1969-01-15 1971-02-16 Cryodry Corp Microwave oven
US3624335A (en) * 1970-06-25 1971-11-30 Raytheon Co Microwave oven
US3654417A (en) * 1970-10-30 1972-04-04 Litton Precision Prod Inc Microwave oven including air flow system
US3749874A (en) * 1972-06-02 1973-07-31 Raytheon Co Microwave applicator

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3365562A (en) * 1962-12-17 1968-01-23 Cryodry Corp Apparatus and process for microwave treatment
US3475827A (en) * 1967-12-06 1969-11-04 Bechtel Int Corp R.f. seal in microwave drier
US3564187A (en) * 1969-01-15 1971-02-16 Cryodry Corp Microwave oven
US3624335A (en) * 1970-06-25 1971-11-30 Raytheon Co Microwave oven
US3654417A (en) * 1970-10-30 1972-04-04 Litton Precision Prod Inc Microwave oven including air flow system
US3749874A (en) * 1972-06-02 1973-07-31 Raytheon Co Microwave applicator

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2642152A1 (de) * 1975-10-09 1977-04-21 Nicolas Meisel Tunnelofen
US4246462A (en) * 1975-10-09 1981-01-20 Nicolas Meisel Microwave tunnel oven for the continuous processing of food products
US4045638A (en) * 1976-03-09 1977-08-30 Bing Chiang Continuous flow heat treating apparatus using microwaves
US4330696A (en) * 1978-04-17 1982-05-18 Plastics, Inc. Portable turntable for ovens
US4886948A (en) * 1978-04-17 1989-12-12 Plastics, Inc. Portable turntable with shielded drive motor for microwave ovens
US4216727A (en) * 1978-05-22 1980-08-12 Plastics, Inc. Portable turntable for microwave oven
US4405850A (en) * 1978-10-06 1983-09-20 Raytheon Company Combination microwave heating apparatus
US4239009A (en) * 1979-08-29 1980-12-16 Plastics, Inc. Portable turntable for microwave oven
US4754111A (en) * 1980-03-18 1988-06-28 Plastics, Inc. Portable turntable for ovens
US4861955A (en) * 1987-07-09 1989-08-29 Shen Zhi Yuan Matched absorptive end choke for microwave applicators
US4922731A (en) * 1988-09-30 1990-05-08 Texas Instruments Incorporated Quartz conductive baffles for heat removal and method
US5245149A (en) * 1990-06-21 1993-09-14 Immobiliare Centro Nord S.P.A. Process and device for accelerating the drying of cement mixes
USRE36943E (en) * 1993-07-09 2000-11-07 Gamma-Metrics Modularized assembly for bulk material analyzer
US5523548A (en) * 1994-01-31 1996-06-04 Nec Corporation Electromagnetic wave heater having a cone-shaped container whose tapered portion is pointed and directed toward the electromagnetic wave generator
US20030183623A1 (en) * 2002-03-29 2003-10-02 Fritts Rex E. Shielding system for protecting select portions of a food product during processing in a conveyorized microwave oven
US6717120B2 (en) * 2002-03-29 2004-04-06 Maytag Corporation Shielding system for protecting select portions of a food product during processing in a conveyorized microwave oven
US20070187401A1 (en) * 2003-10-22 2007-08-16 Sergio Quinta Microwaves blocker apparatus for opening microwaves oven
WO2014195450A1 (de) * 2013-06-07 2014-12-11 Dieffenbacher GmbH Maschinen- und Anlagenbau Anlage, mikrowellendurchlaufofen und verfahren zur kontinuierlichen herstellung von werkstoffen, bevorzugt von werkstoffplatten
US11412584B2 (en) 2017-12-08 2022-08-09 Alkar-Rapidpak, Inc. Ovens with metallic belts and microwave launch box assemblies for processing food products
US11751296B2 (en) 2017-12-08 2023-09-05 Alkar-Rapidpak, Inc. Ovens with metallic belts and microwave launch box assemblies for processing food products
US20220346198A1 (en) * 2021-04-26 2022-10-27 Alkar-Rapidpak, Inc. Food Processing Machines With Microwave Heating Systems And Microwave Suppression Systems

Also Published As

Publication number Publication date
CA999055A (en) 1976-10-26
CH555516A (de) 1974-10-31
IT1003673B (it) 1976-06-10
AT326232B (de) 1975-11-25
SE393732B (sv) 1977-05-16
NL7403361A (de) 1974-10-15
DE2407927A1 (de) 1974-10-24
ATA218674A (de) 1975-02-15
GB1461177A (en) 1977-01-13

Similar Documents

Publication Publication Date Title
US3909574A (en) Microwave tunnel-ovens
CA1101497A (en) Microwave tunnel oven for the continuous processing of food products
US3783219A (en) Air cooled microwave cooking oven and door
US1814897A (en) Apparatus for utilizing solar heat
US3767884A (en) Energy seal for high frequency energy apparatus
US2467230A (en) Ultra high frequency dielectric heater
US3790735A (en) Inductive heated bake oven
US4405850A (en) Combination microwave heating apparatus
US3365562A (en) Apparatus and process for microwave treatment
US3845270A (en) Microwave heating and vapor condensing apparatus
US4861955A (en) Matched absorptive end choke for microwave applicators
US4718332A (en) Electric toaster
US4227063A (en) Microwave apparatus seal
US4189629A (en) Apparatus and method for microwave heating in a kiln
US4176267A (en) Microwave energy trap
US4358653A (en) Combination microwave oven
USRE32664E (en) Energy seal for high frequency energy apparatus
DE7833340U1 (de) Mikrowellenherd oder -ofen
US3239643A (en) Ultra-high frequency heating system
US2175307A (en) Electric heater
US3488858A (en) Microwave apparatus for the processing or measurement of sheet materials
CA1114453A (en) Combination microwave and resistively heated oven
US3665142A (en) System for applying microwave energy to a lossy cylindrical object
US3474208A (en) Devices for heating non-metallic materials in an electromagnetic radiation field
RU2141179C1 (ru) Устройство для свч-конвективной сушки диэлектрических материалов