US3235702A - High-frequency oven - Google Patents

High-frequency oven Download PDF

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Publication number
US3235702A
US3235702A US318057A US31805763A US3235702A US 3235702 A US3235702 A US 3235702A US 318057 A US318057 A US 318057A US 31805763 A US31805763 A US 31805763A US 3235702 A US3235702 A US 3235702A
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United States
Prior art keywords
frequency
waveguide
energy
partition wall
ultrahigh
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
US318057A
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English (en)
Inventor
Timmerma Franciscus Hendricus
Helm Johan Posthuma Van Der
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US Philips Corp
North American Philips Co Inc
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US Philips Corp
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Publication date
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Publication of US3235702A publication Critical patent/US3235702A/en
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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
    • H05B6/78—Arrangements for continuous movement of material
    • H05B6/788—Arrangements for continuous movement of material wherein an elongated material is moved by applying a mechanical tension to it
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
    • 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

  • the oven comprises an ultrahigh-frequency generator for supplying high frequency oscillations to a folded wave-guide system in the form of a plurality of waveguide pieces located side by side and connected together, every two adjacent wave-guide pieces being separated from one another by a common boundary wall.
  • the wave-guide system is provided with a channel for passage therethrough of the object to be heated in a direct-ion transverse to the common boundary walls of the wave-guide pieces located side by side.
  • Each boundary wall has an aperture therein to permit passage of the object.
  • the present invention relates to a high-frequency oven of the kind mentioned in the preamble in which the possibilities of application are considerably extended in a very simple manner by making such high-frequency ovens suitable for ultrahigh-frequency generators of high output, if desired in combination with an increase in the dimensions of the lead-through channel.
  • the height of the lead-through channel may be increased, for example, by a factor of 3, while simultaneously improving the over-all efliciency.
  • a feature of the high-frequency oven according to the invention is that its folded wave guide system is provided with a partition wall separating the wave-guide system for the ultrahigh-frequency oscillations into two separate portions.
  • the ultrahigh-frequency generator is connected to incoupling apertures, locate-d one on each side of the partition wall, through an energy-coupling device which couples in the ultrahigh-frequency oscillations from the ultrahigh-frequency generator through the two incoupling apertures located on each side of the partition wall and without changing the propagation mode of the Wave.
  • FIG. 1 is a perspective view of one embodiment of a high-frequency oven according to the invention.
  • FIG. 2 is a cross-sectional view of the high-frequency oven shown in FIG. 1.
  • the high-frequency oven of FIG. 1 comprises a magnetron generator 1 which is designed for producing oscillations having a wavelength of, for example, 12 cm.
  • the ultrahigh-frequency oscillations are supplied to a folded waveguide system, housed in a box 2, which has the shape of a plurality of waveguide pieces 3 located side by side and connected together, every two adjacent waveguide pieces 3 being separated from one another by a common boundary wall 4.
  • ultrahigh-frequency oscillations of the TE mode are propagated through the folded waveguide system so that the electric field vector has a direction of polarisation transverse to the common boundary Walls.
  • the folded waveguide system 3 is provided with a leadthrough channel in a direction transverse to the boundary walls 4 of the juxtaposed waveguide pieces 3 which for this purpose each have a slotted lead-through aperture in a direction parallel to the boundary wall 4.
  • the outlet aperature 5 of the lead-through channel is shown in FIG. 1 whereas the inlet aperture 5 (see FIG. 2) cannot be seen in this figure.
  • an object 6 to be heated is thus moved through the lead-through channel, for example an object in the form of a band-shaped foil which is driven by driving rollers (not shown), the ultrahigh-frequencies of the TE mode are propagated through the sequential waveguide pieces 3 along the object 6 to be heated, resulting in this object being high-frequency heated in succession in the sequential waveguide pieces 3.
  • Such high-frequency heating of the object is very effective, but a considerable amount of stray radiation occurs outside the high-frequency oven through the inlet and outlet apertures 5' and 5, respectively, of the lead-through channel. This stray radiation is responsible for the fact that heretofore magnetron generators 1 of low power only could be used in the high frequency oven.
  • the folded waveguide system 3 is provided with a partition wall 7 which divides the waveguide system 3 for the ultrahigh-frequency oscillations into two separate portions 8 and 9.
  • the magnetron generator 1 is connected to incoupling aperatures 10 and 11, located one on each side of the partition wall 7, through an energy-coupling device which couples the ultrahigh-frequency oscillations from the magnetron generator 1, without change of the propagation mode of the wave, through the two incoupling apertures 10, 11 located in each side of the partition wall 7 into the folded waveguide system 3.
  • the energy-coupling device comprises a co-axial line 12 connected to the magnetron generator.
  • the inner conductor 13 of the coaxial line extends in a direction transverse to the boundary walls 4 of the waveguide pieces 3 into a connecting waveguide 14 which surrounds the two incoupling apertures 10 and 11 located in each side on the partition wall 7.
  • the partition wall furthermore comprises a division wall 15 which extends further from a point located between the inner conductor 13 of the coaxial line 12 and the coupling apertures 10 and 11 in the 3 partition wall 7.
  • the connecting waveguide 14 extends in a direction away from the coupling slots 10 and 11 to a point beyond the co-axial inner conductor 13 for the purpose of positioning a short-circuit piston 16 therein which serves to match the load to the magnetron generator 1.
  • the ultrahigh-frequency oscillations originating from the magnetron generator 1 are coupled through the coaxial inner conductor 13 into the connecting waveguide 14 as an electromagnetic field of the TE mode with the electric field vector in a direction parallel to the co-axial inner conductor 13.
  • the electromagnetic field thus coupled into the waveguide conductor 14 is supplied, after division by the division wall 15, through the incoupling apertures 10 and 11 on each side of the partition wall 7 as two separate electromagnetic fields of the TE mode.
  • the high-frequency oscillations coupled by the co-axial inner conductor 13 into the connecting waveguide 14 are supplied as two separate electromagnetic fields one on each side of the partition wall 7 of the waveguide system 3 substantially without disturbing the TE mode of the wave so that energy losses, reflection phenomena and the like are substantially avoided.
  • Each of the two said electromagnetic fields is led from the partition wall 7 in relatively opposite directions through the two separate portions 8, 9 of the waveguide system 3 towards the inlet and outlet apertures 5' and 5, respectively, of the lead-through channel.
  • the magnetron generator 1 is designed for an output of 5 kilowatts.
  • an improvement of the efficiency can also be achieved by matching the two energy portions supplied on each side of the partition wall 7 to the loads locally occurring. More particularly, this division of energy may be obtained in a simple manner by suitable positioning of the division wall in the connecting waveguide 14 and of the partition wall 7 in the waveguide system 3. If desired, for this purpose, the division Wall 15 may be arranged in the connecting waveguide 14 to be pivotable about a spindle located near the coupling slots 10, 11. In fact, more accurate matching of the load constituted by the object to be heated is thus obtained, which load usually has undergone a change in magnitude on its way through the high-frequency oven as a result of the heating process.
  • the improved matching of the load means an increased absorption of energy in the object 6 to be heated, resulting in a reduction in the stray radiation and in improvement in efliciency.
  • FIG. 2 shows a cross-section of the high-frequency oven of FIG. 1.
  • Data for a high-frequency oven which has been extensively tested in practice is given below:
  • the high-frequency oven can be made suitable for high-frequency heating of objects of other kind and size, for example, Pertinax plates having a thickness of 8 mm.
  • a high-frequency oven for heating an object by ultra high-frequency energy including an ultrahigh-frequency generator for supplying ultrahigh frequency oscillations to a folded waveguide system comprising a plurality of Waveguide pieces located side by side and interconnected, every two adjacent waveguide pieces being separated from one another by a common boundary wall, and wherein the waveguide system is provided with a channel for passage therethrough of the object to be heated in a direction transverse to the common boundary walls of the juxtaposed waveguide pieces, each of said walls having a lead-through aperture, the improvement comprising a partition wall in the folded waveguide sysem of the high-frequency oven which divides the waveguide system for the ultrahigh-frequency oscillations into two separate portions, first and second incoupling apertures located one on each side of the partition wall, and energy-coupling means for coupling the ultrahigh-frequency oscillations from the ultrahigh-frequency generator, without variation of the kind of wave, to the two incoupling apertures located on each side of the partition wall.
  • said energy-coupling means is arranged to couple an electromagnetic field of the TE mode into the waveguide pieces having its electric field vector in a direction transverse to the boundary walls of the waveguide pieces, characterized in that the energy coupling means comprises, a co-axial line which is connected to the ultrahigh-frequency generator, a connecting waveguide which surrounds the two incoupling apertures located on either side of the partition wall, the inner conductor of said co-axial line being connected to said connecting waveguide in a direction transverse to the boundary walls of the waveguide pieces, said connecting waveguide further comprising a division wall which extends from the incoupling apertures to a point located between the inner conductor of the co-axial line and the incoupling apertures in the partition wall.
  • a high-frequency oven as claimed in claim 2 further comprising means for pivotally mounting said division wall in the connecting waveguide about a spindle located near the incoupling apertures.
  • High frequency heating apparatus comprising a generator of high frequency energy and a waveguide system, said waveguide system comprising a plurality of wall portions defining an enclosure having an inlet and an outlet aperture for passage therethrough of an object to be heated, said waveguide system further comprising a plurality of spaced planar partition members within said enclosure extending transversely to the direction of passage of said object and defining a plurality of waveguide sections interconnected to form a serpentine path for said high frequency energy, each of said partition members having an aperture therein which together form a channel for passage therethrough of said object in a direction transverse to said partition members, a partition wall in said enclosure arranged to separate said enclosure into first and second separate waveguide portions for the flow of said high frequency energy, and means for supplying said high frequency energy to said first and second waveguide portions comprising first and second energy coupling apertures located on either side of said partition wall, said energy supply means further comprising means coupling said high frequency energy from said generator to said first and second energy coupling apertures.
  • High frequency heating apparatus comprising a generator of high frequency energy and a waveguide system, said waveguide system comprising a plurality of wall portions defining an enclosure and including opposed end walls having apertures therein for passage of an object to be heated, said enclosure further comprising two opposite side walls lying in planes parallel to the direction of passage of said object and a plurality of parallel spaced partition members within said enclosure extending transversely to the direction of passage of said object and interconnected to define a serpentine path for said high frequency energy, said partition members including substantially aligned apertures for passage of said object, a partition wall in said enclosure positioned intermediate said end walls and arranged to separate said enclosure into first and second separate Waveguide sections for the flow of said high frequency energy, said enclosure further comprising first and second energy coupling apertures located on either side of said partition wall for supplying said high frequency energy to said first and second waveguide sections, and waveguide means enclosing said first and second energy coupling apertures and coupling said high frequency generator to said first and second apertures.
  • said partition wall is located substantially midway between said end walls and said first and second energy coupling apertures are located in one of said side walls substantially midway between said end walls, said Waveguide means comprising a waveguide section extending transversely to said side walls and further comprising a division wall extending from said partition wall into said waveguide means for a distance of approximately one-half Wavelength of the high frequency energy generated by said high frequency generator.
  • High frequency heating apparatus comprising an enclosed waveguide system including first and second opposed end walls having an inlet and an outlet aperture therein, respectively, for passage of an object to be heated through said enclosed waveguide system, said waveguide system further comprising two opposed side walls and a plurality of spaced partition members within said waveguide system which extend transversely to the direction of passage of said object and interconnected to define a serpentine path for said high frequency energy, each of said partition members including an aperture therein which together form a channel for passage of said object, a partition wall in said waveguide system positioned intermediate said end walls and arranged to separate said waveguide system into first and second separate waveguide sections in the direction of passage of said object, said waveguide system further comprising first and second energy coupling apertures located on either side of said partition wall for supplying high frequency energy to said first and second waveguide sections, source means external to said waveguide system for generating high frequency electromagnetic wave energy, and energy coupling means for supplying said wave energy to said first and second energy coupling apertures whereby said energy propagates through said first and second waveguide sections
  • said energy coupling means comprises a waveguide structure enclosing said first and second energy coupling apertures, and means positioned within said waveguide structure and adjacent said first and second energy coupling apertures for separating said high frequency energy into two separate portions.
  • Apparatus as described in claim 12 wherein said separating means comprises a single movable partition member for changing the ratio of energy of said two separate portions.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Constitution Of High-Frequency Heating (AREA)
US318057A 1962-10-26 1963-10-22 High-frequency oven Expired - Lifetime US3235702A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL284802 1962-10-26

Publications (1)

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US3235702A true US3235702A (en) 1966-02-15

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US318057A Expired - Lifetime US3235702A (en) 1962-10-26 1963-10-22 High-frequency oven

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US (1) US3235702A (sk)
BE (1) BE639202A (sk)
CH (1) CH414037A (sk)
DE (1) DE1515060A1 (sk)
DK (1) DK104360C (sk)
ES (1) ES292831A1 (sk)
GB (1) GB982171A (sk)
NL (1) NL284802A (sk)
SE (1) SE322303B (sk)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3471672A (en) * 1967-04-28 1969-10-07 Varian Associates Slotted waveguide applicator
US3474208A (en) * 1967-03-13 1969-10-21 Herbert August Puschner Devices for heating non-metallic materials in an electromagnetic radiation field
US3500012A (en) * 1967-03-07 1970-03-10 Kenneth Hilton Microwave heating apparatus
US3571551A (en) * 1968-04-03 1971-03-23 Furukawa Electric Co Ltd High frequency heating apparatus
US3590202A (en) * 1970-02-24 1971-06-29 Bechtel Corp Construction for tuning microwave heating applicator
US3622733A (en) * 1970-01-28 1971-11-23 Cryodry Corp Method and apparatus for drying sheet materials
US3632946A (en) * 1968-12-05 1972-01-04 Joel Henri Auguste Soulier Microwave furnace for continuous heat treating of various pieces of dielectric material
US3700847A (en) * 1970-07-06 1972-10-24 Armour & Co System for continuous processing of vienna sausage using microwave energy
US3710064A (en) * 1971-06-03 1973-01-09 Mac Millan Bloedel Ltd Microwave drying system
US5217656A (en) * 1990-07-12 1993-06-08 The C. A. Lawton Company Method for making structural reinforcement preforms including energetic basting of reinforcement members
US5866060A (en) * 1989-12-06 1999-02-02 C. A. Lawton Company Method for making preforms

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3261959A (en) * 1962-02-20 1966-07-19 F H Peavey & Company Apparatus for treatment of ore
GB1051091A (sk) * 1963-03-11
GB1172228A (en) * 1966-11-10 1969-11-26 Hirst Microwave Heating Ltd Microwave Heating Device

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2560903A (en) * 1949-08-27 1951-07-17 Raytheon Mfg Co Wave guide dielectric heating apparatus
GB893936A (en) * 1959-07-31 1962-04-18 Associated Electric Ind Ltd Ultra high frequency heating apparatus

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2560903A (en) * 1949-08-27 1951-07-17 Raytheon Mfg Co Wave guide dielectric heating apparatus
GB893936A (en) * 1959-07-31 1962-04-18 Associated Electric Ind Ltd Ultra high frequency heating apparatus

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3500012A (en) * 1967-03-07 1970-03-10 Kenneth Hilton Microwave heating apparatus
US3474208A (en) * 1967-03-13 1969-10-21 Herbert August Puschner Devices for heating non-metallic materials in an electromagnetic radiation field
US3471672A (en) * 1967-04-28 1969-10-07 Varian Associates Slotted waveguide applicator
US3571551A (en) * 1968-04-03 1971-03-23 Furukawa Electric Co Ltd High frequency heating apparatus
US3632946A (en) * 1968-12-05 1972-01-04 Joel Henri Auguste Soulier Microwave furnace for continuous heat treating of various pieces of dielectric material
US3622733A (en) * 1970-01-28 1971-11-23 Cryodry Corp Method and apparatus for drying sheet materials
US3590202A (en) * 1970-02-24 1971-06-29 Bechtel Corp Construction for tuning microwave heating applicator
US3700847A (en) * 1970-07-06 1972-10-24 Armour & Co System for continuous processing of vienna sausage using microwave energy
US3710064A (en) * 1971-06-03 1973-01-09 Mac Millan Bloedel Ltd Microwave drying system
US5866060A (en) * 1989-12-06 1999-02-02 C. A. Lawton Company Method for making preforms
US6001300A (en) * 1989-12-06 1999-12-14 C.A. Lawton Company Method for making rigid three-dimensional preforms using directed electromagnetic energy
US6004123A (en) * 1989-12-06 1999-12-21 C.A. Lawton Company Apparatus for making preforms
US5217656A (en) * 1990-07-12 1993-06-08 The C. A. Lawton Company Method for making structural reinforcement preforms including energetic basting of reinforcement members
US5827392A (en) * 1990-07-12 1998-10-27 C.A. Lawton Company Method for making structural reinforcement preforms including energetic basting of reinforcement members

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Publication number Publication date
DK104360C (da) 1966-05-09
DE1515060A1 (de) 1969-06-19
GB982171A (en) 1965-02-03
SE322303B (sk) 1970-04-06
BE639202A (sk)
ES292831A1 (es) 1963-12-01
CH414037A (de) 1966-05-31
NL284802A (sk)

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