US3440383A - Heating of articles - Google Patents

Heating of articles Download PDF

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Publication number
US3440383A
US3440383A US592108A US3440383DA US3440383A US 3440383 A US3440383 A US 3440383A US 592108 A US592108 A US 592108A US 3440383D A US3440383D A US 3440383DA US 3440383 A US3440383 A US 3440383A
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United States
Prior art keywords
waveguide
container
package
article
heating
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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
US592108A
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English (en)
Inventor
Peter Harold Smith
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Microtherm Ltd
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Microtherm Ltd
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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
    • H05B6/6402—Aspects relating to the microwave cavity
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S99/00—Foods and beverages: apparatus
    • Y10S99/14—Induction heating

Definitions

  • a microwave heating device for heating food articles has a microwave source and a waveguide connected to the source and with a normally open end adjacent the food article.
  • the food articles are contained in individual disposable containers including a conductive sheet surrounding all but one side of each container, the latter being permeable to the microwave energy.
  • the containers are positioned with the permeable side adjacent the open end of the waveguide, to extend the waveguide and enclose it around the food article, which serves as a load for the microwave energy.
  • a pressure sensitive device is connected to the waveguide to furnish a signal indicating when an air-tight coupling exists between the waveguide and the container.
  • This invention relates to the heating of articles by microwave or similar electromagnetic energy.
  • the invention is particularly, but not exclusively, applicable to the heating of food products, especially at a point of sale.
  • the invention can be used in other circumstances where relatively small articles are to be heated in this way.
  • the present invention has for its object to provide a simpler arrangement than those hitherto suggested, by in effect locating the article to be heated directly within the waveguide or similar feed device.
  • a package including the article to be heated enclosed within a container is removably secured in juxtaposition to a feed device, such as a waveguide, the package providing a termination for the -feed device, so that energy can be fed through the feed device to the load presented by the article with a minimum of mismatch and with a minimum of radiation leakage to the surroundings.
  • FIGURE 1 is a diagrammatic vertical cross-sectional view through a heating device and a package including an article to be heated;
  • FIGURE 2 is a diagrammatic plan view of the package shown in FIGURE 1;
  • FIGURE 3 is a diagrammatic perspective view of the package shown in FIGURE 2;
  • FIGURE 4 is a diagrammatic vertical cross-sectional View through a modified heating arrangement and a moditied form of package
  • FIGURE 5 is a diagrammatic sectional View of a detail of a heating apparatus, showing ay connection flange;
  • FIGURE 6 is a diagrammatic side elevation view of 3,440,383 Patented Apr. 22, 1969 means for clamping in position on the end of a heating apparatus an article to be heated;
  • FIGURE 7 is an end view of the arrangement shown in FIGURE 6;
  • FIGURE 8 is a diagrammatic cross-sectional view of a modiiied form of the apparatus shown in FIGURE I;
  • FIGURE 9 is a diagrammatic cross-sectional view showing a modified form of feed device and a different form of package including an article to be heated.
  • FIGURE 10 is a detail of FIGURE 9, showing the edge of the package.
  • the apparatus shown in FIGURE 1 comprises a microwave generator consisting of a magnetron 10, coupled to a rectangular waveguide feed tube assembly 11. Energy is coupled from the magnetron into the waveguide in the basic TEm mode by means of a stub antenna 12; the adjacent end of the waveguide is closed by a shortcircuit plate 13.
  • Microwave energy is propagated along the waveguide
  • a package 14 which is removably secured to the waveguide 11, the package including the article to be heated, in this case shown by way of example as a hamburger
  • the package is arranged so that it forms a termination for the waveguide 11, with the article 15 forming a resistive load for the radiation.
  • the container has an electrically conductive wall portion 19 which is substantially impermeable to the radiation, and conductive anges 17 and 18 respectively on the waveguide 11 and the wall portion 19 of the package co-operate to seal the joint against radiation.
  • the wall portion 19 deiines a cavity in which the article 15 is located, the cavity having an open end at 20, which is permeable to radiation,
  • the article 15 is spaced from the closed end wall and the shorter side walls of the cavity since the heating energy falls away towards these walls, but may be engaged by the wider side walls of the cavity.
  • the package 14 is mounted to the waveguide 11.
  • the cross-section of the package at the end 20 is arranged to be the same as that of the waveguide 11, so as to present an effectively continuous surface at the joint to the radiation, and the food package is arranged to absorb rnost of the power reected 'f from the end wall of the container.
  • the wall portion 19 of the container may be made of metallic or metallised foil, or metallised plastics material, or metallised or metallic coated board.
  • Metallic foil is presently preferred, as being simpler to form in the required shapes than metallised plastics or board material.
  • the shape of the container is related to the article 15 which is contained within it.
  • the cavity formed by the wall portion 19 is shaped to ensure the optimum distribution of heating energy in the article 15, and this may be contrasted with the usual kind of microwave oven cavity which is adapted to receive a variety of articles, and whose shape is according a compromise, not especially suited for any particular article.
  • the end of the container is rounded as at 21 in FIGURE 2 to conform to the shape of the article.
  • the container should provide a complete enclosure for the article .15. Accordingly, the end 20 of the container may be closed by a film or the like 22 of a material permeable to microwave energy, such as a transparent plastic. It is not essential that the closure provided by the film 22 should be wholly nonconducting, provided that it is adequately transmissive to microwave energy.
  • the microwave heating apparatus should form a static installation and that the package, including the article to be heated, and its container, forms a separate unit which is secured to the end of the waveguide to receive heating energy, the package being subsequently removed from the waveguide, and extracted from the container for consumption.
  • the container 16 has means of readily opening it to give access to the heated contents, and for this purpose the wall of the container is perforated or otherwise weakened, for instance to provide a tear strip 23, FIGURE 3, which surrounds the container.
  • the container can then be readily separated into two parts, and one of these two parts may serve as a holder for the heated article whilst it is being consumed.
  • the magnetron generator 10 is provided with a cooling motor-driven fan 25 and by means of a suitable duct or cowling 26 coolant air is passed over the magnetron
  • the waveguide has in its openings 27 which are of a size such as to be substantially impermeable to microwave energy, leading into the waveguide, so that the now warmed air driven by the blower 25 will pass into the waveguide, as indicated by arrows 28.
  • the article to be heated has its cotnainer 16, as before, coupled to the waveguide, but the container in this case is made permeable to air, so that the warm air can pass through the container.
  • the container can be of material which is inherently permeable to air or of perforated but otherwise impermeable material.
  • the passage of the heated dry air over the article 15 has the efr'ect of reducing the degree to which it may become damp or soggy due to any steam that is generated as it is heated.
  • FIGURE S illustrates a means of further reducing leakage of microwave energy from between the anges 17 and 18.
  • the iiange 17 has a portion 30 which denes a recess, in which is disposed a dielectric material having a relatively large loss factor.
  • a lossy double quarter-wave choke is formed. This much reduces leakage of energy.
  • FIGURES 6 and 7 show a suitable means by which this can be accomplished.
  • a plate or sheet 31, which may form part 0f a shell for the heating apparatus, is fastened to ilange 17. Plate 31 has in it an opening corresponding to the open end of the waveguide.
  • Locating means are provided for the flange 18 of the container, which can take various forms but are shown as upper pegs or pins 32 which engage in corresponding apertures in the flange 18, and lower pegs 33 which engage the lower edge of the ilange 18. In this way the two ilanges are brought accurately into register.
  • the abutting tlanges are adapted to be held by a U-shaped clamping plate 34 which is hinged along its lower edge at 35 to the edge or a part of plate 31.
  • the plate 34 can be swung away from the pins 32 and 33, to enable the flange 18 to be slipped between the plate 34 and the ange 17.
  • the plate 34 may have lateral projections 36 and 37 which serve to locate the flange 18 when it is initially inserted.
  • the plate 34 is pulled into clamping engagement with the flange 18 by means of a solenoid 39, the plunger 40 of which' is pivoted at 41 to arms 42, 43, which are attached to the extremities of the arms of plate 34.
  • the operation of solenoid 39 is linked with the control apparatus which is associated with the operation of the magnetron, so that clamping pressure will be automatically applied by the solenoid when the cycle of the heating operation is started.
  • FIG- URE. ⁇ 8 a means of monitoring this general condition is indicated in FIG- URE. ⁇ 8.
  • a differential pressure is established between the interior and exterior of the waveguide; if the seal between the flanges 17 and 18 is not properly made, the differential pressure will be reduced and can be detected by pressure sensitive means.
  • the article to be heated is of the kind the end wall of which is not permeable to air, so that when the flanges 17 and 18 are in contact the waveguide should be hermetically sealed.
  • a pump 44 such as a small vacuum pump, is in communication with the interior of the waveguide through a pipe 45, and a pressure sensitive switch 46, with a diaphragm 47 and switch 48, is also in communication with the interior of the waveguide through pipe 49.
  • the switch 48 will be operated in one way when the pump 44 is in operation, but if there should be a leak in the system then the switch will not operaate in this manner and suitable supervisory alarm or control means can be operated.
  • the pump 44 is started at the beginning of the cycle, and that the switching on of the magnetron is controlled by the closure of switch 48 when adequate vacuum pressure has been established with the waveguide.
  • this arrangement In some circumstances, depending upon the nature of the package to be heated, it is possible to use this arrangement to ensure that the package 14 is not opened, or cracked or, if initially sealed, has had the seal fractured in any way. If the diaphragm 22 is permeable to air, a partial vacuum should be maintained inside the container 15, and the pressure diiferential will again be greater for a perfect container, properly positioned, than for an imperfect container or imperfect joint with the waveguide 11. If the wall portion 19 is permeable to air, the arrangement can be used to draw oit any steam or cooking vapours which may be generated by the article 15 when it is being heated.
  • the cross-sectional dimensions of the waveguide are usually chosen to be sufficiently small to support only one propagation mode, and if this arrangement is adopted it clearly imposes a practical limitation on the size of the article that can be heated conveniently.
  • FIGURES 9 and 10 is shown an arrangement in which substantially larger articles appropriately packaged, can be heated by direct inclusion in a waveguide system, while avoiding problems which can be caused by reection of power back to the magnetron by avoiding mismatches in the system.
  • the microwave generator 10 has the coupling aerial 12 as before, and this extends into a short waveguide launching section 50, which can be of either circular or rectangular cross-section as may be convenient.
  • This waveguide section is terminated at its one end by the short-circuit plate 13.
  • the other end of the waveguide 50 is coupled to a ⁇ tapered section 52, of gradually increasing cross-sectional area from its junction with section 50 to an outermost section 53, which is shaped to receive the package 14, presented by the article 54 to be heated, and its container.
  • the container is composed of two parts, a dished portion 55 which is made of a low loss material permeable to microwave energy and an outer cover 56 which is impermeable to microwave radiation, and can be, for example, of metal foil.
  • the outer edge 57 of the tray-like portion of the container is embraced by the edge of the foil cover 56, which is turned over, as at 57, so that it is in good contact with a flange 58 formed around the end of section 53.
  • the package can be positioned on the open end of the waveguide system, the cover portion 56 of the container forming a termination for the waveguide.
  • a flange 58 is formed around the edge of the cover 56, and co-operates with a corresponding flange on the portion 53 of the waveguide system to form a radiation seal.
  • the cover 56 is shaped to ensure an optimum distribution of heating energy in the contents of the package, and is spaced from the contents.
  • the package may be circular or rectangular in crosssection and the flange 58 formed around the edge of section 53 has a corresponding cross-section. It may be convenient for the tapered section 52 to have a cross-sectional shape which resembles that of the article, in order to secure a more uniform distribution of energy throughout the article. It is also arranged that the tapering of the section gives a good impedance match between the article and the launching section 50. In order to prevent the leakage of energy, it is desirable to use a clamping means, such as a ring 60 which firmly clamps the foil-covered edge of the container to the liange 58. In this case, the foil cover 56 may be perforated if desired, to allow the escape of any steam produced in the heating process. The perforations should be of a size to prevent any substantial leakage of microwave energy.
  • a package comprising an article to be heated and a container in which said article is received, said container including a first wall portion which is substantially impermeable to said radiant energy and a second wall portion which is permeable to said radiant energy, an end of said feed device being ⁇ adapted to receive said package whereby said article is positioned to receive said radiant energy, said first wall portion and said end of the feed dev-ice being adapted to couple together when said package is received by the end of the feed device, whereby said package forms a termination for said feed) device, said package being adapted to form a substantially hermetic seal to said end of the feed device when received correctly thereby, and means for detecting incorrect positioning of the package comprising means for generating a pressure differential between the interior of said feed device and its surroundings, and means responsive to the magnitude of said pressure differential.
  • heating apparatus for heating a food article contained within a disposable container by exposing said food article to radiant energy while in said container, the combination comprising a source of radiant energy, a waveguide having a first flange on a normally open end and its other end connected to said source, said container having a conductive wall portion and a second flange adapted to be connected with said first iiange to extend said waveguide and close said open end when said container is juxtaposed with said open end so that said extended waveguide includes the space within said package, whereby said food article may be heated by said radiant energy.
  • Apparatus according to claim 2 including a plurality of containers containing different food articles, each of said conta-iners including a conductive wall portion adapted to extend said waveguide and close said open end when said container is juxtaposed with said open end, said conductive wall portion of each container surrounding a food article, at least some of said food articles being of different size or shape from the others, each of said containers having a size and shape related to the characterstics of the food articles within it, whereby the optimum distribution of heating energy in the food article is obtained.
  • said feed device includes a first hollow waveguide section, connecting means for connecting said first waveguide section to said source, the cross-section of said first waveguide section being substantially uniform along its length and being 'chosen so that said first waveguide section can maintain only one mode of radiation from said connecting means, and a hollow waveguide taper section which extends betwen said 'first waveguide section and said end of the feed device, the cross-section of said taper section being substant-ially identical to that of said rst waveguide section where they meet; and increasing progressively towards said end of the feed device.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Constitution Of High-Frequency Heating (AREA)
  • Cookers (AREA)
US592108A 1965-11-04 1966-11-04 Heating of articles Expired - Lifetime US3440383A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB46842/65A GB1164278A (en) 1965-11-04 1965-11-04 Improvements in and relating to the Heating of Articles.

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US3440383A true US3440383A (en) 1969-04-22

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Application Number Title Priority Date Filing Date
US592108A Expired - Lifetime US3440383A (en) 1965-11-04 1966-11-04 Heating of articles

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US (1) US3440383A (de)
DE (1) DE1565731A1 (de)
FR (1) FR1510898A (de)
GB (1) GB1164278A (de)
SE (1) SE329451B (de)

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3569657A (en) * 1969-09-16 1971-03-09 Melvin L Levinson Method of processing and transporting articles
US3632946A (en) * 1968-12-05 1972-01-04 Joel Henri Auguste Soulier Microwave furnace for continuous heat treating of various pieces of dielectric material
US3854219A (en) * 1973-06-18 1974-12-17 Gen Electric Electronic dryer
US3881403A (en) * 1973-03-30 1975-05-06 Baker Perkins Inc Apparatus for making bread and like food products
US4045639A (en) * 1973-01-16 1977-08-30 Food Processing Systems Corporation Continuous microwave and vacuum dryer
FR2363309A1 (fr) * 1976-08-31 1978-03-31 Pruines Iseco Sa De Plateau individuel pour repas conditionne
US4107502A (en) * 1976-04-06 1978-08-15 Matsushita Electric Industrial Co., Ltd. Microwave oven
US4276462A (en) * 1978-01-02 1981-06-30 Husqvarna Aktiebolag Microwave heating apparatus
DE3024178A1 (de) * 1980-06-27 1982-01-21 Licentia Gmbh Mikrowellenheizgeraet
US4356640A (en) * 1980-07-02 1982-11-02 Christian Jansson Method of drying clothes and heating up laundry water and apparatus therefor
WO1990003714A1 (en) * 1988-09-28 1990-04-05 Core Consulting Group Limited Microwave-powered heating chamber
WO1990003717A1 (en) * 1988-09-28 1990-04-05 Core Consulting Group Limited Improved microwave-powered heating device
WO1990003715A1 (en) * 1988-09-28 1990-04-05 Core Consulting Group Limited Improved microwave-powered heating device
WO1990003718A1 (en) * 1988-09-28 1990-04-05 Core Consulting Group Limited Microwave-powered heating chamber
WO1990003719A1 (en) * 1988-09-28 1990-04-05 Core Consulting Group Limited Improved microwave-powered apparatus
FR2722638A1 (fr) * 1994-07-13 1996-01-19 Marzat Claude Dispositif applicateur de micro-ondes notamment pour la cuisson de produits sur un support metallique
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
WO1996042185A1 (en) * 1995-06-09 1996-12-27 Cobolt Systems Limited Oven
WO1997026777A1 (fr) * 1996-01-19 1997-07-24 Belin-Lu Biscuits France Dispositif applicateur de micro-ondes notamment pour la cuisson de produits sur un support metallique
US20100116821A1 (en) * 2008-11-13 2010-05-13 Kabushiki-Kaisha Takumi Structure heating system by microwave, microwave oscillation waveguide apparatus and microwave oscillator cooling method

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH591049A5 (de) * 1975-12-17 1977-08-31 Elektromaschinen Ag
DE3019720C2 (de) * 1980-05-23 1983-06-01 Jung GmbH, 6050 Offenbach Mikrowellenheizvorrichtung für umwälzbare Medien
DE3743922A1 (de) * 1987-12-23 1989-07-06 Bosch Siemens Hausgeraete Mikrowellengarmulde
DE102016221083A1 (de) * 2016-10-26 2018-04-26 BSH Hausgeräte GmbH Gargerät und Verfahren zum Fertigen eines Gargeräts

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2586754A (en) * 1946-11-16 1952-02-19 Raytheon Mfg Co Radio-frequency system
US2599033A (en) * 1946-11-15 1952-06-03 Raytheon Mfg Co High-frequency apparatus
US2820127A (en) * 1953-03-30 1958-01-14 Raytheon Mfg Co Microwave cookers
US2827537A (en) * 1953-11-12 1958-03-18 Raytheon Mfg Co Electronic heating apparatus
US2993973A (en) * 1959-04-06 1961-07-25 Westinghouse Electric Corp Microwave oven apparatus

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2599033A (en) * 1946-11-15 1952-06-03 Raytheon Mfg Co High-frequency apparatus
US2586754A (en) * 1946-11-16 1952-02-19 Raytheon Mfg Co Radio-frequency system
US2820127A (en) * 1953-03-30 1958-01-14 Raytheon Mfg Co Microwave cookers
US2827537A (en) * 1953-11-12 1958-03-18 Raytheon Mfg Co Electronic heating apparatus
US2993973A (en) * 1959-04-06 1961-07-25 Westinghouse Electric Corp Microwave oven apparatus

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3632946A (en) * 1968-12-05 1972-01-04 Joel Henri Auguste Soulier Microwave furnace for continuous heat treating of various pieces of dielectric material
US3569657A (en) * 1969-09-16 1971-03-09 Melvin L Levinson Method of processing and transporting articles
US4045639A (en) * 1973-01-16 1977-08-30 Food Processing Systems Corporation Continuous microwave and vacuum dryer
US3881403A (en) * 1973-03-30 1975-05-06 Baker Perkins Inc Apparatus for making bread and like food products
US3854219A (en) * 1973-06-18 1974-12-17 Gen Electric Electronic dryer
US4107502A (en) * 1976-04-06 1978-08-15 Matsushita Electric Industrial Co., Ltd. Microwave oven
FR2363309A1 (fr) * 1976-08-31 1978-03-31 Pruines Iseco Sa De Plateau individuel pour repas conditionne
US4276462A (en) * 1978-01-02 1981-06-30 Husqvarna Aktiebolag Microwave heating apparatus
DE3024178A1 (de) * 1980-06-27 1982-01-21 Licentia Gmbh Mikrowellenheizgeraet
US4356640A (en) * 1980-07-02 1982-11-02 Christian Jansson Method of drying clothes and heating up laundry water and apparatus therefor
WO1990003715A1 (en) * 1988-09-28 1990-04-05 Core Consulting Group Limited Improved microwave-powered heating device
US5142114A (en) * 1988-09-28 1992-08-25 Briggs David H Microwave chamber for heating foodstuffs
WO1990003714A1 (en) * 1988-09-28 1990-04-05 Core Consulting Group Limited Microwave-powered heating chamber
WO1990003718A1 (en) * 1988-09-28 1990-04-05 Core Consulting Group Limited Microwave-powered heating chamber
WO1990003719A1 (en) * 1988-09-28 1990-04-05 Core Consulting Group Limited Improved microwave-powered apparatus
AU619909B2 (en) * 1988-09-28 1992-02-06 Unilever Plc Microwave-powered heating chamber
AU619919B2 (en) * 1988-09-28 1992-02-06 Unilever Plc Improved microwave-powered heating device
WO1990003717A1 (en) * 1988-09-28 1990-04-05 Core Consulting Group Limited Improved microwave-powered heating device
US5144105A (en) * 1988-09-28 1992-09-01 Briggs David H Microwave heating apparatus with a combined food scoop and door
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
FR2722638A1 (fr) * 1994-07-13 1996-01-19 Marzat Claude Dispositif applicateur de micro-ondes notamment pour la cuisson de produits sur un support metallique
WO1996042185A1 (en) * 1995-06-09 1996-12-27 Cobolt Systems Limited Oven
WO1997026777A1 (fr) * 1996-01-19 1997-07-24 Belin-Lu Biscuits France Dispositif applicateur de micro-ondes notamment pour la cuisson de produits sur un support metallique
US20100116821A1 (en) * 2008-11-13 2010-05-13 Kabushiki-Kaisha Takumi Structure heating system by microwave, microwave oscillation waveguide apparatus and microwave oscillator cooling method

Also Published As

Publication number Publication date
SE329451B (de) 1970-10-12
FR1510898A (fr) 1968-01-26
DE1565731A1 (de) 1971-09-23
GB1164278A (en) 1969-09-17

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