US3196242A - High-frequency oven door seal - Google Patents

High-frequency oven door seal Download PDF

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Publication number
US3196242A
US3196242A US232732A US23273262A US3196242A US 3196242 A US3196242 A US 3196242A US 232732 A US232732 A US 232732A US 23273262 A US23273262 A US 23273262A US 3196242 A US3196242 A US 3196242A
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US
United States
Prior art keywords
seal
door
aperture
chamber
dielectric
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
US232732A
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English (en)
Inventor
Vries Peke Jan De
Visser Jacobus Bernardus
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.)
US Philips Corp
North American Philips Co Inc
Original Assignee
US Philips Corp
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 US Philips Corp filed Critical US Philips Corp
Application granted granted Critical
Publication of US3196242A publication Critical patent/US3196242A/en
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
    • H05B6/66—Circuits
    • H05B6/666—Safety circuits
    • 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
    • H05B6/763—Microwave radiation seals for doors
    • 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
    • H05B6/766—Microwave radiation screens for windows
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields

Definitions

  • the invention relates to a high-frequency oven for high-frequency heating food with the aid of ultra highfrequency oscillations, for example oscillations in the decimeter or centimeter range, which comprises an ultrahigh-frequency generator the output circuit of which is coupled to a heating chamber enclosed by metal walls and provided with an aperture for introducing the articles to be heated into the oven and with a door which in the closed position closes the heating chamber and. forms a seal against emanation of stray radiation.
  • An object of the present invention is to provide, in a high-frequency furnace of the type described above a new concept of sealing with respect to emanating stray radiation which not only has remarkable simplicity of construction permitting simple and effective cleaning but also ensures effective sealing under all operating conditions.
  • the arrangement in accordance with the invention is characterized in that at least one of the sealing walls situated outside the feed aperture in a direction pointing away from this feed aperture comprises two successive sealing frames surrounding the feed aperture which in the closed position of the door engage the opposite wall so as to be substantially flush therewith, the sealing frame adjoining the feed aperture consisting of metal and the following sealing frame consisting of a dielectric material in which is distributed a powdered substance which absorbes ultra high-frequency oscillations.
  • Suitable dielectric materials are, for example, synthetic materials, especially synthetic resins, for example epoxy resins, urea or phenolic resins and polyester resins, and ceramic materials, while especially powdered graphite when used as the material absorbing the ultra high-frequency radiation provides excellent results.
  • FIGURE 1 is a vertical cross sectional view of the high-frequency furnace in accordance with the invention
  • FlGURES 2 and 3 are a partial view of a front elevation of the sealing frames provided on the closing wall of the oven and a vertical sectional view showing the sealing construction of FIG. 2 in greater detail.
  • the high-frequency oven in accordance with the invention comprises a metal housing 1 which is horizontally divided into two compartments 2 and 3, the upper compartment 2 comprising a heating chamber 4 enclosed by metal walls while the lower compartment 3 contains an ultra high-frequency generator in the form of a magnetron generator 5 and a control panel 6 with the associated control instruments and control knobs.
  • the output circuit of the magnetron generator 5 is coupled to a wave guide 7 for the transmission of the ultra high-frequency oscillations produced, one end of the wave guide '7 being connected to an input coupling aperture 8 in the upper wall of the heating chamber 4 while in order to provide load matching for the magnetron generator 5 the other end is provided with matching means, for example, in the form of a known matching piston 9.
  • the front wall of the high-frequency oven is provided with a feed aperture it for articles 11 to be heated, which are introduced into the heating chamber 4 on a dielectric plate 12 of loss-free material, and with a door 14 which is operated with the aid of a handle 13 and in the closed position closes the heating chamber 4 by its metal front wall.
  • the door 14 is hinged to the housing wall by a curved hinge member 15 and is provided with a locking mechanism 16 which locks the door 14 to the casing wall in the closed position.
  • the door 1 3 when closed is flush with the housing of the high-frequency furnace.
  • Uniformity of the dielectric heating is promoted by a field stirrer 1'7 which is arranged in the wave guide 7 over the input coupling aperture 8 and is driven by a motor not shown in the figure.
  • a field stirrer 1'7 which is arranged in the wave guide 7 over the input coupling aperture 8 and is driven by a motor not shown in the figure.
  • an outwardly extending closing Wall surface is provided in the plane 18 on said chamber 4 which together with the inner wall of the door 14 forms a seal against stnay radiation in a manner described more fully hereinafter.
  • the invention provides a remarkably simple and particularly effective sealing construction in that a closing wall in plane 18 situated in the plane of the feed aperture it) and extending in a direction pointing away from said aperture 19 comprises two successive or concentric sealing frames 19 and Eli which surround the feed aperture ill and in the closed position of the door 14, engage the adjacent wall of the door 14 so as to be flush therewith, the sealing frame I9 adjoining the aperture 10 consisting of metal and the following sealing frame 2t consisting of a dielectric material in which a powdered substance is distributed which absorbs the ultra high-frequency oscillations.
  • the dielectric material of the sealing frame 20 is an epoxy resin (araldite) and the material absorbing the ultra high-frequency radia- .tion energy is powdered graphite.
  • FIGURES 2 and 3 show, side by side, a front elevation of the sealing frames 19 and 2% comprising on the closing wall 18 and a cross-sectional view of the sealing construction used which, as will be described more fully hereinafter, ensures an effective reduction of the stray radiation emanating from the high-frequency furnace.
  • the ultra-highfrequency oscillations set up in the heating chamber 4 are to emanate from the high-frequency furnace, they have to pass through the narrow gap between the metal sealing frame 19 adjoining the feed aperture ft and the inner wall of metal door 14 and when travelling in a direction pointing away from the feed aperture 10 they are guided by the metal walls of the sealing frame 19 and the door 14- after the manner of a wave guide and at the dielectric sealing frame 2%) they are dispersed in a direction at right angles to the gap between the sealing frame 19 and the door wall, since at this point the metallic wave guide is interrupted, The larger part of the emanating radiation penetrates into the dielectric sealing frame 2%!
  • the dielectric constant of the dielectric material is large, for example, about 3, and the ultra high-frequency radiation penetrating into the sealing frame 26 is absorbed by the powdered graphite distributed therein.
  • the metal sealing frame 19 adjoining the feed aperture in and the door wall not only form a first seal but also cause decoupling of the heating chamber 4 from the dielectric sealing frame 2h which, as described hereinbefore, ensures that the ultrahigh-frequency radiation is not only dispersed but also absorbed.
  • an epoxy resin other dielectric materials may be used for the sealing frame 29, for example, synthetic resins such as urea and phenolic resins (Philite) and polyester resins, and ceramic material, while powdered graphite provides particularly satisfactory results when used as the material absorbing the ultra high-frequency radiation.
  • synthetic resins such as urea and phenolic resins (Philite) and polyester resins, and ceramic material
  • powdered graphite provides particularly satisfactory results when used as the material absorbing the ultra high-frequency radiation.
  • a same percentage by weight of the powdered absorbing material proves to give optimum conditions, for example a percentage by weight of approximately from 20%-40% when powdered graphite is used.
  • the sealing construction described not only is level and hence permits of simple and effective cleaning but also proves to be only slightly dependent upon the widthof the gap between the two sealing frames 1.9 and 2t) and the inner wall of the door 14, and this is apparently due to the fact that increasing the width of the gap increases the absorbing effect of the sealing frame 2% by increasing the dispersing effect.
  • the emanating stray radiation was only at most 7 mw./cm. at a distance of 5 c-rns. from the edge of the door 14.
  • the said sealing construction ensures an effective suppression of the emanating stray radiation and this property is' also of particular importance for the manufacture of the high-frequency furnaces under consideration because no special tolerance requirements need to be satisfied.
  • the face of the dielectric sealing frame 2d, remote from the door 14, to be open in order to intercept any radiation having passed through the said sealing frame 2d in the enclosed space bounded by the walls of the housing 1 and the heating chamber 4 where it can do no damage.
  • slit-shaped apertures 22 are provided for this purpose in a metal support 21 of. the sealing frame 20.
  • An additional safety step may be to provide on the dielectric sealing frame 20 a microswitch (not shown) in the form of a resilient pin which, when a maximum permissible width of the gap between the sealing frame ing chamber, means for supplying high frequency energy to said chamber, a feed aperture in said chamber for introducing food articles to said chamber, a metallic door for closing said opening, a metallic decoupling seal surrounding said feed aperture and having a planar contact surface in the plane of said aperture engageable with said door in the closed position thereof, a successive nonconductive dielectric seal concentrically surrounding and directly adjoining said metallic seal, said successive di+ electric seal having a contact surface engageable with said door in the plane of said aperture, said second seal consisting of a dielectric material containing 20-40 percent by weight of powdered graphite distributed therethro-ugh for dispersing and absorbing said energy existing between said door and said seals.
  • a high frequency oven door seal comprising a heatmg chamber, means for supplying high frequency energy to said chamber, a feed aperture in said chamber for introducing food articles to said chamber, a metallic door for closing said opening, a metallic decoupling seal surrounding said feed aperture and having a planar contact surface in the plane of said aperture engageable with said door in the closed position thereof, a successive nonconductive dielectric seal concentrically surrounding and directly adjoining said metallic seal, said successive dielectric seal having a contact surface engageable with said door in the plane of said aperture, said second seal consisting of a dielectric material having powdered graphite distributed therethrough for dispersing and absorbing said energy existing between said door and said seals, said successive dielectric seal having an unobstructed surface opposite said contact surface communicating with a space defined by an oven enclosure and the walls of said heating chamber.
  • a high frequency oven door seal comprising a heating chamber, means for supplying high frequency energy to said chamber, a feed aperture in said chamber for introducing food articles to said chamber, a metallic door for closing said opening, a metallic decoupling seal surrounding said feed aperture and having a planar contact surface in the plane of said aperture engageable With said door in the closed position thereof, a successive nonconductive dielectric seal concentrically surrounding and directly adjoining said metallic seal, said successive dielectric seal having a contact surface engageable with said door in the plane of said aperture, said second seal consisting of a dielectric material containing 2040 percent by weight of powdered graphite distributed therethrough for dispersing and absorbing said energy existing between said door and said seals, said successive dielectric seal having an unobstructed surface opposite said contact surface communicating with a space defined by an oven enclosure and the walls of said heating chamber.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Electric Ovens (AREA)
  • Constitution Of High-Frequency Heating (AREA)
  • Package Closures (AREA)
US232732A 1961-10-25 1962-10-24 High-frequency oven door seal Expired - Lifetime US3196242A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL270618 1961-10-25

Publications (1)

Publication Number Publication Date
US3196242A true US3196242A (en) 1965-07-20

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ID=19753359

Family Applications (1)

Application Number Title Priority Date Filing Date
US232732A Expired - Lifetime US3196242A (en) 1961-10-25 1962-10-24 High-frequency oven door seal

Country Status (7)

Country Link
US (1) US3196242A (US07714131-20100511-C00038.png)
CH (1) CH435493A (US07714131-20100511-C00038.png)
DE (1) DE1195884B (US07714131-20100511-C00038.png)
DK (1) DK104896C (US07714131-20100511-C00038.png)
ES (1) ES281795A1 (US07714131-20100511-C00038.png)
GB (1) GB1010922A (US07714131-20100511-C00038.png)
NL (1) NL113797C (US07714131-20100511-C00038.png)

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3339054A (en) * 1964-04-20 1967-08-29 Gen Motors Corp Electronic oven
US3351730A (en) * 1964-03-10 1967-11-07 Philips Corp Energy seal for microwave ovens
US3402277A (en) * 1965-10-25 1968-09-17 Patelhold Patentverwertung Microwave treating device
US3436508A (en) * 1965-08-26 1969-04-01 Karl Fritz Cabinet and door construction for microwave heating appliances
US3448232A (en) * 1967-01-11 1969-06-03 Hammtronics Systems Inc Microwave unit seal
US3522550A (en) * 1966-09-29 1970-08-04 Philips Corp High frequency heating device including a self-excited velocity modulation tube generator for continuous operation
US3525841A (en) * 1968-11-04 1970-08-25 Litton Precision Prod Inc Door seal for microwave ovens
US3584177A (en) * 1969-10-24 1971-06-08 Amana Refrigeration Inc Energy seal for microwave oven apparatus
US3641301A (en) * 1969-09-10 1972-02-08 Mitsubishi Electric Corp Microwave oven
US3733456A (en) * 1971-09-07 1973-05-15 Amana Refrigeration Inc Microwave oven door latch
US3742176A (en) * 1969-06-26 1973-06-26 Tdk Electronics Co Ltd Method for preventing the leakage of microwave energy from microwave heating oven
US3784776A (en) * 1970-04-20 1974-01-08 Tokyo Shibaura Electric Co Electromagnetic locking mechanism for a microwave oven
US3794797A (en) * 1971-04-19 1974-02-26 Matsushita Electric Ind Co Ltd Leakage preventing microwave oven
US3846608A (en) * 1974-02-11 1974-11-05 Litton Systems Inc High temperature resistant door seal for a microwave oven
US4144436A (en) * 1976-06-17 1979-03-13 General Electric Company Microwave oven excitation system for promoting uniformity of energy distribution
US4166207A (en) * 1977-05-31 1979-08-28 Whirlpool Corporation Microwave generating device--door seal
FR2885004A1 (fr) * 2005-04-22 2006-10-27 Premark Feg Llc Four a micro-ondes avec un cache pour piege a ondes
WO2013092477A1 (de) * 2011-12-20 2013-06-27 E.G.O. Elektro-Gerätebau GmbH Haushaltsgerät zum erwärmen von lebensmitteln

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4197860A (en) * 1977-11-21 1980-04-15 Rca Corporation Hyperthermia applicator
DE102010043537A1 (de) 2010-11-08 2012-05-10 BSH Bosch und Siemens Hausgeräte GmbH Haushaltsgerät

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2364790A (en) * 1941-09-13 1944-12-12 Du Pont Treatment of organic dielectric materials with high-frequency electric current
US2374515A (en) * 1942-04-18 1945-04-24 British Insulated Cables Ltd Heat treatment of the insulating coverings of electric wires and cables
US2393541A (en) * 1943-05-21 1946-01-22 Induction Heating Corp Composition adapted for inductive heating and method for using same
US2632838A (en) * 1948-03-04 1953-03-24 Gen Electric Ultrahigh-frequency electromag-netic radiation heating method and apparatus
US2839649A (en) * 1956-05-17 1958-06-17 Gen Electric Control circuits for electronic ranges
US2956143A (en) * 1958-06-05 1960-10-11 Raytheon Co Microwave ovens
US2958754A (en) * 1958-12-15 1960-11-01 Gen Electric Electronic ovens

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2364790A (en) * 1941-09-13 1944-12-12 Du Pont Treatment of organic dielectric materials with high-frequency electric current
US2374515A (en) * 1942-04-18 1945-04-24 British Insulated Cables Ltd Heat treatment of the insulating coverings of electric wires and cables
US2393541A (en) * 1943-05-21 1946-01-22 Induction Heating Corp Composition adapted for inductive heating and method for using same
US2632838A (en) * 1948-03-04 1953-03-24 Gen Electric Ultrahigh-frequency electromag-netic radiation heating method and apparatus
US2839649A (en) * 1956-05-17 1958-06-17 Gen Electric Control circuits for electronic ranges
US2956143A (en) * 1958-06-05 1960-10-11 Raytheon Co Microwave ovens
US2958754A (en) * 1958-12-15 1960-11-01 Gen Electric Electronic ovens

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3351730A (en) * 1964-03-10 1967-11-07 Philips Corp Energy seal for microwave ovens
US3339054A (en) * 1964-04-20 1967-08-29 Gen Motors Corp Electronic oven
US3436508A (en) * 1965-08-26 1969-04-01 Karl Fritz Cabinet and door construction for microwave heating appliances
US3402277A (en) * 1965-10-25 1968-09-17 Patelhold Patentverwertung Microwave treating device
US3522550A (en) * 1966-09-29 1970-08-04 Philips Corp High frequency heating device including a self-excited velocity modulation tube generator for continuous operation
US3448232A (en) * 1967-01-11 1969-06-03 Hammtronics Systems Inc Microwave unit seal
US3525841A (en) * 1968-11-04 1970-08-25 Litton Precision Prod Inc Door seal for microwave ovens
US3742176A (en) * 1969-06-26 1973-06-26 Tdk Electronics Co Ltd Method for preventing the leakage of microwave energy from microwave heating oven
US3641301A (en) * 1969-09-10 1972-02-08 Mitsubishi Electric Corp Microwave oven
US3584177A (en) * 1969-10-24 1971-06-08 Amana Refrigeration Inc Energy seal for microwave oven apparatus
US3784776A (en) * 1970-04-20 1974-01-08 Tokyo Shibaura Electric Co Electromagnetic locking mechanism for a microwave oven
US3794797A (en) * 1971-04-19 1974-02-26 Matsushita Electric Ind Co Ltd Leakage preventing microwave oven
US3733456A (en) * 1971-09-07 1973-05-15 Amana Refrigeration Inc Microwave oven door latch
US3846608A (en) * 1974-02-11 1974-11-05 Litton Systems Inc High temperature resistant door seal for a microwave oven
US4144436A (en) * 1976-06-17 1979-03-13 General Electric Company Microwave oven excitation system for promoting uniformity of energy distribution
US4166207A (en) * 1977-05-31 1979-08-28 Whirlpool Corporation Microwave generating device--door seal
FR2885004A1 (fr) * 2005-04-22 2006-10-27 Premark Feg Llc Four a micro-ondes avec un cache pour piege a ondes
US20080149629A1 (en) * 2005-04-22 2008-06-26 Premark Feg L.L.C. Microwave Oven With a Mask For Wave Trap
WO2013092477A1 (de) * 2011-12-20 2013-06-27 E.G.O. Elektro-Gerätebau GmbH Haushaltsgerät zum erwärmen von lebensmitteln

Also Published As

Publication number Publication date
DE1195884B (de) 1965-07-01
CH435493A (de) 1967-05-15
ES281795A1 (es) 1962-12-16
DK104896C (da) 1966-07-18
NL113797C (US07714131-20100511-C00038.png)
GB1010922A (en) 1965-11-24

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