WO2016103585A1 - マイクロ波加熱装置 - Google Patents

マイクロ波加熱装置 Download PDF

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Publication number
WO2016103585A1
WO2016103585A1 PCT/JP2015/006017 JP2015006017W WO2016103585A1 WO 2016103585 A1 WO2016103585 A1 WO 2016103585A1 JP 2015006017 W JP2015006017 W JP 2015006017W WO 2016103585 A1 WO2016103585 A1 WO 2016103585A1
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WIPO (PCT)
Prior art keywords
microwave
waveguide structure
opening
coupling
tube axis
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PCT/JP2015/006017
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English (en)
French (fr)
Japanese (ja)
Inventor
吉野　浩二
貞平　匡史
昌之 久保
大森　義治
早川　雄二
Original Assignee
パナソニックＩｐマネジメント株式会社
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.)
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Application filed by パナソニックＩｐマネジメント株式会社 filed Critical パナソニックＩｐマネジメント株式会社
Priority to CN201580064897.7A priority Critical patent/CN107006084B/zh
Priority to JP2016565885A priority patent/JP6503561B2/ja
Priority to EP15872162.1A priority patent/EP3240363B1/en
Publication of WO2016103585A1 publication Critical patent/WO2016103585A1/ja

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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
    • H05B6/72—Radiators or antennas
    • H05B6/725—Rotatable antennas
    • 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
    • H05B6/70—Feed lines
    • H05B6/707—Feed lines using waveguides
    • H05B6/708—Feed lines using waveguides in particular slotted waveguides
    • 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
    • H05B6/74—Mode transformers or mode stirrers

Definitions

  • the present disclosure relates to a microwave heating apparatus such as a microwave oven that heats an object to be heated such as food using microwaves.
  • microwaves generated by a magnetron which is a typical microwave generation unit, are supplied into a metal heating chamber and placed in a heating chamber.
  • the heated object is heated by microwave.
  • Patent Document 1 has a waveguide structure magnetically coupled to a waveguide that propagates microwaves from a magnetron.
  • FIG. 12 is a front sectional view showing the configuration of the microwave oven 100 disclosed in Patent Document 1. As shown in FIG. 12, in the microwave oven 100, the microwave generated by the magnetron 101 propagates through the waveguide 102 and reaches the coupling axis 109.
  • the rotating antenna 103 has a fan shape in plan view from above, is connected to the waveguide 102 by a coupling shaft 109, and is driven by a motor 105 to rotate.
  • the coupling shaft 109 couples the microwave propagating through the waveguide 102 to the waveguide-structured rotating antenna 103 and functions as the rotation center of the rotating antenna 103.
  • the rotating antenna 103 has a radiation port 107 for radiating microwaves and a low impedance portion 106.
  • the microwave radiated from the radiation port 107 is supplied into the heating chamber 104, and the object to be heated (not shown) placed on the placing table 108 of the heating chamber 104 is microwave-heated.
  • the rotating antenna 103 is rotated below the mounting table 108 to make the heating distribution in the heating chamber 104 uniform.
  • a microwave oven that controls the stop position of the rotating antenna based on the temperature distribution in the heating chamber detected by an infrared sensor (see, for example, Patent Document 2).
  • FIG. 13 is a front cross-sectional view showing the configuration of the microwave oven 200 disclosed in Patent Document 2. As shown in FIG. As shown in FIG. 13, in the microwave oven 200, the microwave generated by the magnetron 201 reaches the rotating antenna 203 having a waveguide structure via the waveguide 202.
  • the rotary antenna 203 has a radiation port 207 that is formed on one side and radiates microwaves in a plan view from above, and a low impedance part 206 that is formed on the other three sides.
  • the microwave radiated from the radiation port 207 is supplied into the heating chamber 204 through the power supply chamber 209, and the object to be heated placed in the heating chamber 204 is heated by microwaves.
  • the microwave oven disclosed in Patent Document 2 has an infrared sensor 210 for detecting the temperature distribution in the heating chamber 204.
  • the control unit 211 controls the rotation and position of the rotating antenna 203 and the direction of the radiation port 207 based on the temperature distribution detected by the infrared sensor 210.
  • a rotating antenna 203 disclosed in Patent Document 2 is configured to move on an arc-shaped track while rotating inside a power feeding chamber 209 formed below a mounting table 208 of a heating chamber 204 by a motor 205.
  • the microwave oven 200 the radiation port 207 of the rotating antenna 203 moves while rotating, and the low temperature portion of the object to be heated detected by the infrared sensor 210 can be heated intensively.
  • the rotating antenna 103 is configured to rotate around a coupling shaft 109 disposed below the mounting table 108.
  • the microwave is radiated from the radiation port 107 at the tip of the rotating antenna 103.
  • the object to be heated placed in the central region of the placing table 108 could not be directly irradiated with microwaves, and uniform heating was not always possible.
  • the present disclosure solves the above-described conventional problems, and provides a smaller microwave heating apparatus capable of uniformly heating an object to be heated placed on a placement surface in a heating chamber, particularly a central region thereof.
  • the purpose is to provide.
  • a microwave heating apparatus includes a heating chamber that stores an object to be heated, a microwave generation unit that generates a microwave, a ceiling surface and a side wall surface that define a waveguide structure unit, and a front opening. And a waveguide structure antenna that radiates microwaves from the front opening to the heating chamber.
  • the waveguide structure portion is joined to the ceiling surface and has a coupling portion that couples the microwave to the internal space of the waveguide structure portion.
  • the waveguide structure has at least one microwave suction opening formed on the ceiling surface, and radiates circularly polarized waves from the microwave suction opening into the heating chamber.
  • the joint portion between the coupling portion and the waveguide structure portion is configured such that the length in the tube axis direction is shorter than the length in the direction orthogonal to the tube axis direction.
  • FIG. 1 is a cross-sectional view illustrating a schematic configuration of a microwave heating apparatus according to an embodiment of the present disclosure.
  • FIG. 2A is a perspective view showing a power supply chamber in the microwave heating apparatus according to the present embodiment.
  • FIG. 2B is a plan view showing a power supply chamber in the microwave heating apparatus according to the present embodiment.
  • FIG. 3 is an exploded perspective view showing a rotating antenna in the microwave heating apparatus according to the present embodiment.
  • FIG. 4 is a perspective view showing a general rectangular waveguide.
  • FIG. 5A is a plan view showing an H-plane of a waveguide having a rectangular slot-shaped opening that radiates linearly polarized waves.
  • FIG. 5A is a plan view showing an H-plane of a waveguide having a rectangular slot-shaped opening that radiates linearly polarized waves.
  • FIG. 5A is a plan view showing an H-plane of a waveguide having a rectangular slot-shaped opening that radiates linearly polarized
  • FIG. 5B is a plan view showing an H-plane of a waveguide having a cross-slot-shaped opening that radiates circularly polarized waves.
  • FIG. 5C is a front view showing the positional relationship between the waveguide and the object to be heated.
  • FIG. 6A is a characteristic diagram showing experimental results for the waveguide shown in FIG. 5A.
  • FIG. 6B is a characteristic diagram showing an experimental result in the case of the waveguide shown in FIG. 5B.
  • FIG. 7 is a characteristic diagram showing experimental results in the case of “with load”.
  • FIG. 8A is a cross-sectional view schematically showing a suction effect in the present embodiment.
  • FIG. 8B is a cross-sectional view schematically showing the suction effect in the present embodiment.
  • FIG. 9A is a schematic diagram illustrating a planar shape of an example of the rotating antenna used in the experiment.
  • FIG. 9B is a schematic diagram illustrating a planar shape of an example of the rotating antenna used in the experiment.
  • FIG. 9C is a schematic diagram illustrating a planar shape of an example of the rotating antenna used in the experiment.
  • FIG. 10A is a schematic diagram illustrating a planar shape of an example of the rotating antenna used in the experiment.
  • FIG. 10B is a schematic diagram illustrating a planar shape of an example of the rotating antenna used in the experiment.
  • FIG. 11 is a plan view showing the waveguide structure according to the present embodiment.
  • FIG. 12 is a front sectional view showing the microwave oven disclosed in Patent Document 1.
  • FIG. 13 is a front sectional view showing the microwave oven disclosed in Patent Document 2. As shown in FIG.
  • a microwave heating apparatus includes a heating chamber that houses an object to be heated, a microwave generation unit that generates a microwave, a ceiling surface and a side wall surface that define a waveguide structure, and A waveguide structure antenna having a front opening and radiating microwaves from the front opening to the heating chamber.
  • the waveguide structure portion is joined to the ceiling surface and has a coupling portion that couples the microwave to the internal space of the waveguide structure portion.
  • the waveguide structure has at least one microwave suction opening formed on the ceiling surface, and radiates circularly polarized waves from the microwave suction opening into the heating chamber.
  • the joint portion between the coupling portion and the waveguide structure portion is configured such that the length in the tube axis direction is shorter than the length in the direction orthogonal to the tube axis direction.
  • the microwave heating apparatus further includes a drive unit that rotates the waveguide structure antenna in addition to the first aspect.
  • the coupling portion has a coupling shaft and a flange.
  • the coupling axis is connected to the drive unit and includes the rotation center of the waveguide structure antenna.
  • the flange is provided around the coupling axis and constitutes a joint portion.
  • the flange has a length in the tube axis direction that is shorter than a length in a direction orthogonal to the tube axis direction.
  • the object to be heated placed in the central region of the placement surface can be heated more uniformly.
  • the microwave heating apparatus further includes a drive unit that rotates the waveguide structure antenna in addition to the first aspect.
  • the coupling unit is coupled to the driving unit and has a coupling axis including the rotation center of the waveguide structure antenna.
  • the cross section of the joint portion in the joint portion has a length in the tube axis direction that is shorter than the length in the direction orthogonal to the tube axis direction.
  • the object to be heated placed in the central region of the placement surface can be heated more uniformly.
  • the microwave suction opening has a cross slot shape in which two slits intersect and is displaced from the tube axis. It is provided at a certain position. According to this aspect, it is possible to radiate circularly polarized waves more reliably from the microwave suction opening.
  • the waveguide structure portion has at least two microwave suction openings that are symmetrical with respect to the tube axis, The distance between the two microwave suction openings in the region near the coupling portion is longer than the distance between the two microwave suction openings in the region separated from the coupling portion.
  • the heating chamber can be more uniformly heated by the circularly polarized wave radiated from the microwave suction opening.
  • the ceiling surface of the waveguide structure portion has a recess provided in the joint portion. According to this aspect, the object to be heated placed in the central region of the placement surface can be heated more uniformly.
  • a microwave oven is used as an example of a microwave heating apparatus according to the present disclosure, but the present invention is not limited to this, and a heating apparatus, a garbage disposal machine, or a semiconductor manufacture using microwave heating is not limited thereto. Including devices.
  • the present disclosure is not limited to the specific configurations shown in the following embodiments, and includes configurations based on the same technical idea.
  • FIG. 1 is a front sectional view showing a schematic configuration of a microwave oven that is a microwave heating apparatus according to an embodiment of the present disclosure.
  • the left-right direction of the microwave oven means the left-right direction in FIG. 1
  • the front-back direction means the depth direction in FIG.
  • the microwave oven 1 includes a heating chamber 2a, a power feeding chamber 2b, a magnetron 3, a waveguide 4, a rotating antenna 5, and a mounting table 6.
  • the mounting table 6 has a flat upper surface for mounting an object to be heated (not shown) such as food.
  • the heating chamber 2 a is an upper space of the mounting table 6, and the power supply chamber 2 b is a lower space of the mounting table 6.
  • the mounting table 6 covers the power supply chamber 2b provided with the rotating antenna 5, partitions the heating chamber 2a and the power supply chamber 2b, and constitutes the bottom surface of the heating chamber 2a. Since the upper surface (mounting surface 6a) of the mounting table 6 is flat, it is easy to put in and out the object to be heated, and it is easy to wipe off dirt and the like attached to the mounting surface 6a.
  • the mounting table 6 is made of a material that easily transmits microwaves, such as glass and ceramic, the microwave radiated from the rotating antenna 5 passes through the mounting table 6 and is supplied to the heating chamber 2a.
  • the magnetron 3 is an example of a microwave generation unit that generates a microwave.
  • the waveguide 4 is an example of a propagation unit that is provided below the power supply chamber 2 b and transmits the microwave generated by the magnetron 3 to the coupling unit 7.
  • the rotating antenna 5 is provided in the internal space of the power supply chamber 2b, and radiates the microwave transmitted by the waveguide 4 and the coupling portion into the power supply chamber 2b from the front opening 13.
  • the rotating antenna 5 includes a waveguide structure portion 8 having a box-shaped waveguide structure in which microwaves propagate in the internal space, and a microwave in the waveguide 4 and the internal space of the waveguide structure portion 8. It is a waveguide structure antenna having a coupling portion 7 to be coupled.
  • the coupling unit 7 includes a coupling shaft 7 a coupled to the motor 15 that is a driving unit, and a flange 7 b that joins the waveguide structure unit 8 and the coupling unit 7.
  • the motor 15 is driven in accordance with a control signal from the control unit 17 to rotate the rotating antenna 5 around the coupling shaft 7a of the coupling unit 7 and stop it in a desired direction. Thereby, the radiation direction of the microwave from the rotating antenna 5 is changed.
  • a metal such as an aluminum-plated steel plate is used for the coupling portion 7, and, for example, a fluororesin is used for a coupling portion of the motor 15 coupled to the coupling portion 7.
  • the coupling shaft 7a of the coupling portion 7 passes through an opening that communicates the waveguide 4 and the power supply chamber 2b, and the coupling shaft 7a has a predetermined clearance (for example, 5 mm or more) between the penetrating opening.
  • the coupling shaft 7 a couples the waveguide 4 and the internal space of the waveguide structure portion 8 of the rotating antenna 5, so that the microwave propagates efficiently from the waveguide 4 to the waveguide structure portion 8.
  • An infrared sensor 16 is provided on the upper side of the heating chamber 2a.
  • the infrared sensor 16 is an example of a state detection unit that detects the temperature in the heating chamber 2a, that is, the surface temperature of the heated object placed on the mounting table 6 as the state of the heated object.
  • the infrared sensor 16 detects the temperature of each region of the heating chamber 2 a virtually divided into a plurality of parts, and transmits those detection signals to the control unit 17.
  • the control unit 17 performs oscillation control of the magnetron 3 and drive control of the motor 15 based on the detection signal of the infrared sensor 16.
  • This embodiment has the infrared sensor 16 as an example of the state detection unit, but the state detection unit is not limited to this.
  • a weight sensor that detects the weight of the object to be heated or an image sensor that captures an image of the object to be heated may be used as the state detection unit.
  • the control unit 17 may perform the oscillation control of the magnetron 3 and the drive control of the motor 15 in accordance with a program stored in advance and a selection by the user.
  • FIG. 2A is a perspective view showing the power supply chamber 2b in a state where the mounting table 6 is removed.
  • FIG. 2B is a plan view showing the power supply chamber 2b in the same situation as FIG. 2A.
  • a rotating antenna 5 is provided in a power supply chamber 2b that is disposed below the heating chamber 2a and is separated from the heating chamber 2a by the mounting table 6.
  • the rotation center G of the coupling shaft 7a in the rotating antenna 5 is located below the center of the feed chamber 2b in the front-rear direction and the left-right direction, that is, below the center of the mounting table 6 in the front-rear direction and the left-right direction.
  • the feeding chamber 2 b has an internal space constituted by the bottom surface 11 and the lower surface of the mounting table 6.
  • the internal space of the power supply chamber 2b includes the rotation center G of the coupling portion 7 and has a symmetrical shape with respect to the center line J (see FIG. 2B) in the left-right direction of the power supply chamber 2b.
  • a convex portion 18 protruding inward is formed on the side wall surface in the internal space of the power supply chamber 2b.
  • the convex portion 18 includes a convex portion 18a provided on the left side wall surface and a convex portion 18b provided on the right side wall surface.
  • a magnetron 3 is provided below the convex portion 18b.
  • the microwave radiated from the antenna 3 a of the magnetron 3 propagates in the waveguide 4 provided below the feeding chamber 2 b and is transmitted to the waveguide structure 8 by the coupling portion 7.
  • the side wall surface 2c of the feeding chamber 2b has an inclination for reflecting the microwave radiated from the rotating antenna 5 in the horizontal direction toward the upper heating chamber 2a.
  • FIG. 3 is an exploded perspective view showing a specific example of the rotating antenna 5.
  • the waveguide structure 8 has a ceiling surface 9 and side wall surfaces 10a, 10b, and 10c that define its internal space.
  • the ceiling surface 9 includes three linear edges, one arc-shaped edge, and a concave portion 9a to which the coupling portion 7 is joined, and is disposed to face the mounting table 6 (see FIG. 1). ).
  • Side wall surfaces 10a, 10b, and 10c are formed by bending downward from the three linear edges of the ceiling surface 9, respectively.
  • the side wall surface is not provided at the arc-shaped edge, and an opening is formed below the side wall surface.
  • This opening functions as a front opening 13 that radiates the microwave propagated through the internal space of the waveguide structure 8. That is, the side wall surface 10b is provided to face the front opening 13, and the side wall surfaces 10a and 10c are provided to face each other.
  • a low impedance portion 12 extending outwardly of the waveguide structure 8 and in a direction perpendicular to the side wall surface 10a.
  • the low impedance portion 12 is formed in parallel with the bottom surface 11 of the power supply chamber 2b with a slight gap therebetween.
  • the low impedance portion 12 suppresses microwaves that leak in the direction perpendicular to the side wall surface 10a.
  • a holding portion 19 for mounting an insulating resin spacer may be formed on the lower surface of the low impedance portion 12.
  • the low impedance portion 12 is provided with a plurality of slits 12a extending periodically from the side wall surface 10a at regular intervals.
  • the plurality of slits 12a suppress microwave leakage in a direction parallel to the side wall surface 10a.
  • the interval between the slits 12 a is appropriately determined according to the wavelength propagating through the waveguide structure 8.
  • the low impedance portion 12 having a plurality of slits 12a at the lower edge portion is also provided for the side wall surface 10b and the side wall surface 10c.
  • the rotating antenna 5 according to the present embodiment has a front opening 13 formed in an arc shape, but the present disclosure is not limited to this shape, and has a straight or curved front opening 13. Also good.
  • the ceiling surface 9 includes a plurality of microwave suction openings 14, that is, a first opening 14a and a second opening 14b having an opening smaller than the first opening 14a.
  • the microwave that has propagated through the internal space of the waveguide structure 8 is radiated from the front opening 13 and the plurality of microwave suction openings 14.
  • the flange 7b formed in the coupling portion 7 is joined to the lower surface of the ceiling surface 9 of the waveguide structure portion 8 by, for example, caulking, spot welding, screw tightening, or welding, and the rotating antenna 5 is joined to the coupling portion 7. And fixed.
  • the rotating antenna 5 since the rotating antenna 5 has a waveguide structure portion 8 as will be described later, it is possible to uniformly heat the object to be heated mounted on the mounting table 6. In particular, in the central region of the mounting surface 6a located above the rotation center G (see FIGS. 2A and 2B) of the rotating antenna 5, heating can be performed efficiently and uniformly.
  • the waveguide structure in the present embodiment will be described in detail.
  • the simplest and most common waveguide 300 has a rectangular cross section 303 having a width a and a height b, and a square having a depth along the tube axis V of the waveguide 300. It is a waveguide.
  • the tube axis V is the center line of the waveguide 300 that passes through the center of the cross section 303 and extends in the microwave transmission direction Z.
  • the TE10 mode is a transmission mode in the H wave (TE wave; electrical transverse wave transmission (Transverse Electric Wave)) in the waveguide 300 in the microwave transmission direction Z, in which the magnetic field component exists and the electric field component does not exist. Point to.
  • H wave TE wave; electrical transverse wave transmission (Transverse Electric Wave)
  • the wavelength ⁇ 0 of the microwave in free space can be obtained by the equation (1).
  • the speed of light c is about 2.998 ⁇ 10 8 [m / s]
  • the oscillation frequency f is 2.4 to 2.5 [GHz] (ISM band in the case of a microwave oven). ). Since the oscillation frequency f varies depending on variations in magnetron and load conditions, the wavelength ⁇ 0 in free space is between a minimum of 120 [mm] (at 2.5 GHz) and a maximum of 125 [mm] (at 2.4 GHz). fluctuate.
  • the width a of the waveguide 300 is designed in the range of 80 to 100 mm and the height b of 15 to 40 mm in consideration of the range of the wavelength ⁇ 0 in free space. There are many cases.
  • the wide surface 301 that is the upper surface and the lower surface is referred to as the H surface in the sense that the magnetic field vortexes in parallel, and the narrow surface 302 that is the left and right side surfaces. In the sense that it is a plane parallel to the electric field, it is called the E plane.
  • a straight line on the H plane in which the tube axis V is projected on the H plane may be referred to as the tube axis V.
  • ⁇ g When the wavelength of the microwave from the magnetron is defined as the wavelength ⁇ 0 and the wavelength of the microwave when propagating in the waveguide is defined as the wavelength ⁇ g in the tube, ⁇ g can be obtained by Expression (2).
  • the guide wavelength ⁇ g varies depending on the width a of the waveguide 300, but is not related to the height b.
  • the electric field is zero at both ends (E plane) of the waveguide 300 in the width direction W, that is, the narrow surface 302, and the electric field is maximum at the center in the width direction W.
  • the same principle as that of the waveguide 300 shown in FIG. 4 is applied to the rotating antenna 5 shown in FIGS.
  • the ceiling surface 9 and the bottom surface 11 of the power supply chamber 2b are H surfaces
  • the side wall surfaces 10a and 10c are E surfaces.
  • the side wall surface 10 b serves as a reflection end for reflecting all the microwaves in the rotating antenna 5 in the direction of the front opening 13.
  • the width a of the waveguide 300 is 106.5 mm.
  • a plurality of microwave suction openings 14 are formed in the ceiling surface 9.
  • the microwave suction opening 14 includes two first openings 14a and two second openings 14b.
  • the two first openings 14 a are symmetric with respect to the tube axis V of the waveguide structure portion 8 of the rotating antenna 5.
  • the two second openings 14b are symmetric with respect to the tube axis V.
  • the first opening 14a and the second opening 14b are formed so as not to cross the tube axis V.
  • the first opening 14a and the second opening 14b are arranged at positions shifted from the tube axis V of the waveguide structure 8 (more precisely, a straight line on the ceiling surface 9 obtained by projecting the tube axis V onto the ceiling surface 9).
  • circularly polarized waves can be more reliably radiated from the microwave suction opening 14.
  • the central region of the mounting surface 6a can be uniformly heated.
  • the rotation direction of the electric field that is, right-handed polarization (CW: Clockwise) or left-handed polarization (CCW: Counterclockwise) It is determined.
  • each of the microwave suction openings 14 is provided so as not to straddle the tube axis V.
  • the present disclosure is not limited to this, and even in a configuration in which a part of these openings crosses the tube axis V, circularly polarized light can be emitted. In this case, a distorted circularly polarized wave is generated.
  • Circular polarization is a technique widely used in the fields of mobile communications and satellite communications. Examples of familiar use include ETC (Electronic Toll Collection System), that is, a non-stop automatic toll collection system.
  • ETC Electronic Toll Collection System
  • Circular polarization is a microwave in which the polarization plane of an electric field rotates with respect to the direction of travel, and the direction of the electric field continues to change with time, and the magnitude of the electric field strength does not change. .
  • this circularly polarized wave is applied to a microwave heating apparatus, it can be expected that the object to be heated will be heated uniformly, particularly in the circumferential direction of the circularly polarized wave, as compared with the conventional microwave heating by linearly polarized wave.
  • the same effect can be obtained with either right-handed polarization or left-handed polarization.
  • Circular polarization is primarily used in the field of communications, and since it is intended for radiation into open spaces, it is generally discussed as a so-called traveling wave with no reflected wave.
  • a reflected wave is generated in the heating chamber 2a that is a closed space, and the generated reflected wave and the traveling wave may be combined to generate a standing wave.
  • either right-handed polarization or left-handed polarization is used for accurate transmission / reception of information, and a receiving antenna having directivity suitable for it is used on the receiving side.
  • a non-directional object to be heated such as food
  • receives microwaves so that the microwave is irradiated to the entire object to be heated. Is important. Therefore, in the field of microwave heating, whether it is right-handed polarized wave or left-handed polarized wave is not important, and there is no problem even if right-handed polarized wave and left-handed polarized wave are mixed.
  • microwave suction effect means that the microwave in the waveguide structure is sucked out from the microwave suction opening 14 when an object to be heated such as food is nearby.
  • FIG. 5A is a plan view of a waveguide 400 having an H plane provided with an opening for generating linearly polarized waves.
  • FIG. 5B is a plan view of a waveguide 500 having an H plane provided with an opening for generating circularly polarized waves.
  • FIG. 5C is a front view showing the positional relationship between the waveguide 400 or 500 and the object 22 to be heated.
  • the opening 401 is a rectangular slit provided so as to intersect the tube axis V of the waveguide 400.
  • the opening 401 radiates linearly polarized microwaves.
  • each of the two openings 501 is a cross-slot-shaped opening formed by two rectangular slits that intersect at right angles.
  • the two openings 501 are symmetric with respect to the tube axis V of the waveguide 500.
  • Each opening is symmetric with respect to the tube axis V of the waveguide, and has a width of 10 mm and a length of Lmm.
  • the case of “no load” in which the object to be heated 22 is not disposed and the case of “with load” in which the object to be heated 22 is disposed were analyzed using CAE.
  • the height of a constant object to be heated 22 is 30 mm, the bottom areas (100 mm square and 200 mm square) of two kinds of objects to be heated 22, and three kinds of objects to be heated With respect to the material of the object 22 (frozen beef, refrigerated beef, water), the distance D from the waveguides 400 and 500 to the bottom surface of the object to be heated 22 was measured as a parameter.
  • FIG. 6A and FIG. 6B show the relationship between the length of the opening and the radiated power in the case of “no load” in order to use the radiated power from the opening in the case of “no load” as a reference.
  • FIG. 6A shows the characteristics in the case of the opening 401 shown in FIG. 5A
  • FIG. 6B shows the characteristics in the case of the opening 501 shown in FIG. 5B
  • the horizontal axis is the length L [mm] of the opening
  • the vertical axis is emitted from the openings 401 and 501 when the power propagating in the waveguide is 1.0 W.
  • the case where the length L was 46.5 mm was selected.
  • FIG. 7 shows three kinds of foods having two kinds of bottom areas (100 mm square and 200 mm square) when the length L is the above length (45.5 mm, 46.5 mm) and “with load” ( Includes six graphs showing the results of analysis on frozen beef, refrigerated beef, and water).
  • the horizontal axis represents the distance D [mm] from the object to be heated 22 to the waveguide
  • the vertical axis represents the radiated power at “no load” as 1.0. It is the relative radiated power when.
  • the object to be heated 22 indicates how much microwaves are sucked out of the waveguides 400 and 500 in the case of “with load”.
  • the broken line indicates the characteristics (indicated by “I” in the figure) in the case of the opening 401 having a linear shape (I shape), and the solid line has two cross slot shapes (X shape).
  • the characteristic in the case of the opening 501 is shown.
  • the opening 501 has more radiated power than the opening 401.
  • the distance D is 20 mm or less, there is a difference of about twice as much as the actual microwave oven. Can be recognized. Therefore, regardless of the type and bottom area of the object to be heated 22, it is clear that the opening that generates circularly polarized waves has a higher microwave absorption effect than the opening that generates linearly polarized waves.
  • frozen beef having a smaller dielectric constant and dielectric loss has a larger suction effect, and water having a larger dielectric constant and dielectric loss.
  • the suction effect is smaller.
  • the inventors examined the conditions of the aperture that can radiate circularly polarized waves through experiments using various aperture shapes. As a result, the following conclusion was reached.
  • the preferable conditions for generating the circularly polarized wave are that the opening is arranged so as to be shifted from the tube axis V of the waveguide, and that the opening shape includes a cross-slot-shaped opening. It is an opening having a cross slot shape that radiates the circularly polarized microwave most efficiently, that is, has a high suction effect.
  • FIGS. 8A and 8B are cross-sectional views schematically showing the suction effect in the present embodiment.
  • the front opening 13 of the rotating antenna 5 faces leftward in the figure in both FIG. 8A and FIG. 8B.
  • the object to be heated 22 is disposed above the coupling portion 7 in FIG. 8A, and is placed at the left corner of the placement surface 6a in FIG. 8B. That is, in the two states shown in FIGS. 8A and 8B, the distance from the coupling portion 7 to the article to be heated 22 is different.
  • the microwave suction opening 14 increases the radiated power when food is placed in the vicinity of the microwave suction opening 14, and the food is located away from the microwave suction opening 14. This is considered to cause a special phenomenon that the radiated power decreases when the is placed.
  • FIG. 9A, FIG. 9B, and FIG. 9C are schematic views respectively showing the planar shapes of three examples of the rotating antenna used in the experiment.
  • the waveguide structure 600 has two first openings 614a and two second openings 614b.
  • the first opening 614a has a cross slot shape, and each rectangular slit is provided in the vicinity of the coupling portion 7 so as to form an angle of 45 degrees with respect to the tube axis V of the waveguide structure portion 600.
  • the second opening 614 b is smaller than the first opening 614 a and is provided apart from the coupling portion 7.
  • the waveguide structure 700 has one first opening 714a having a cross slot shape similar to the first opening 614a, unlike the waveguide structure 600.
  • the waveguide structure 800 has two first openings 814a having a T-shape unlike the waveguide structure 600. That is, unlike the first opening 614a, the first opening 814a does not have a portion extending from the intersecting portion toward the coupling portion 7 in one of the two rectangular slits.
  • a plurality of cross-slot shaped microwave suction openings are provided, and a first opening having a similar size is provided at a similar location.
  • the second opening having the same size is provided at the same place.
  • the second opening 614b, the second opening 714b, and the second opening 814b are the same.
  • the temperature drop in the vicinity of the coupling portion 7 could be suppressed.
  • the temperature drop in the vicinity of the coupling portion 7 could be suppressed.
  • the waveguide structure in which no opening is provided in the vicinity of the coupling portion 7 or only one opening is provided in the vicinity of the coupling portion 7 suppresses a temperature drop in the vicinity of the coupling portion 7. It was confirmed that uniform heating in the heating chamber 2a was possible.
  • the inventors conducted experiments on the shape of the microwave suction opening and found a waveguide structure capable of further uniforming the heating distribution.
  • the first opening 814a of the waveguide structure 800 shown in FIG. 9C radiates a distorted circularly polarized wave, which is different from the circularly polarized wave formed by the cross-slot shaped opening. From the viewpoint of uniform heating in the chamber 2a, a preferable result was not obtained.
  • the first opening 914a having the shape shown in FIGS. 10A and 10B was examined in order to suppress the interference between the two circularly polarized waves and to form the circularly polarized wave as close to the circle as possible.
  • FIG. 10A and FIG. 10B are schematic views respectively showing the planar shapes of the waveguide structure portion 900A and the waveguide structure portion 900B provided with the first opening 914a.
  • the waveguide structures 900A and 900B both have the same first opening 914a and second opening 914b.
  • the first opening 914a is a cross in which, in one of the two rectangular slits, a portion extending from the intersecting portion in the direction of the coupling portion 7 has a shorter length than a portion extending from the intersecting portion in the opposite direction of the coupling portion 7. It has a slot shape.
  • the length of the portion of the first opening 914a extending from the intersecting portion in the direction of the coupling portion 7 is appropriately set according to the specifications so that interference between the two circularly polarized waves does not occur.
  • the waveguide structure 900A has a flat ceiling surface as a whole.
  • a concave joint region (a concave portion 909a which is a step region) is formed in a joint portion where the flange 7b is joined to the ceiling surface (see, for example, FIG. 3). Therefore, on the ceiling surface of the waveguide structure 900B, the distance between the junction region and the mounting table is longer than that of other portions.
  • the waveguide structure 900A suppresses interference between two circularly polarized waves and generates a circularly polarized wave having a shape close to a circle. I was able to.
  • the first opening 914a increases the suction effect, and can suppress the temperature drop in the vicinity of the coupling portion 7. Moreover, it has been found that the temperature decrease in the vicinity of the coupling portion 7 can be suppressed by the concave joining region formed on the ceiling surface of the waveguide structure portion 900B.
  • FIG. 11 is a plan view showing a rotating antenna having the waveguide structure 8 according to the present embodiment.
  • the waveguide structure 8 has a plurality of microwave suction openings 14 provided on the ceiling surface 9.
  • the plurality of microwave suction openings 14 include a first opening 14a and a second opening 14b having an opening smaller than the first opening 14a.
  • the first opening 14a and the second opening 14b have a substantially cross slot shape.
  • the microwave suction opening 14 is circularly polarized. Can radiate.
  • the center point P1 of the first opening 14a and the center point P2 of the second opening 14b are the center points of the intersecting regions of the two slits forming the first opening 14a and the second opening 14b, respectively.
  • first opening 14 a and the second opening 14 b are arranged so as not to cross the tube axis V of the waveguide structure 8.
  • the longitudinal direction of each rectangular slit of the first opening 14a and the second opening 14b has an inclination of substantially 45 ° C. with respect to the tube axis V.
  • the first opening 14 a is formed close to the recess 9 a of the ceiling surface 9.
  • the recess 9a is a step region provided so as to protrude from the ceiling surface 9 in a direction (downward) opposite to the traveling direction of the microwave radiated from the first opening 14a (see FIG. 3).
  • the two first openings 14a are symmetric with respect to the tube axis V.
  • the second opening 14b is formed in the vicinity of the front opening 13 at a distance from the coupling portion 7 than the first opening 14a. Similar to the first opening 14a, the two second openings 14b are symmetric with respect to the tube axis V.
  • the length of the portion extending in the direction from the center point P1 toward the tube axis V is shorter than the length of the portion extending in the direction from the center point P1 to the side wall surface 10a.
  • the flange 7 b provided in the coupling portion 7 has a shape in which the length in the microwave transmission direction Z is shorter than the length in the width direction W of the waveguide structure portion 8. That is, in the coupling unit 7, the length of the microwave transmission direction Z is shorter than the length in the direction orthogonal to the transmission direction Z. According to the flange 7b, the tip of the slit extending from the central point P1 toward the coupling portion 7 can be formed closer to the coupling portion 7.
  • the recess 9a is formed on the front side of the recess 9a by joining the flange 7b such as a protrusion of TOX caulking, a welding mark, a screw, a nut head, or the like. It is comprised so that it may become deeper than the height of the protrusion which arises. According to the present embodiment, there is no problem such that the protrusion contacts the lower surface of the mounting table 6.
  • the waveguide 11 has a recess 9a provided in the ceiling surface 9 above the coupling portion 7, and has the same configuration as the waveguide structure 900B shown in FIG. 10B.
  • the waveguide structure portion 8 shown in FIG. 11 similarly to the waveguide structure portion 900 ⁇ / b> B, a temperature decrease near the coupling portion 7 can be suppressed. There are two possible reasons for this.
  • the internal space of the waveguide structure portion 8 where the recess 9a is formed is narrower than the other portions.
  • the first opening 14a is caused by the suction effect.
  • the object to be heated radiated from the surface and placed in the central region of the placement surface 6a is strongly heated.
  • the first opening 14a includes slits 20a and 20b, and has a cross slot shape in which these intersect at the center point P1.
  • the major axis of each slit of the first opening 14a has an angle of 45 degrees with respect to the tube axis V.
  • the slit 20a extends from the lower right to the upper left of the center point P1, and has a first length A from the center point P1 to the lower right tip and a third length C from the center point P1 to the upper left tip. Have.
  • the lower right tip of the slit 20a is directed toward the coupling portion 7 and close to the recess 9a.
  • the slit 20b extends from the lower left to the upper right of the center point P1, and has a second length B from the center point P1 to the lower left tip and a fourth length D from the center point P1 to the upper right tip. That is, the first length A is the length from the center point P1 to the tips closest to the coupling portion 7 among the lengths from the center point P1 to the tips of the slits 20a and 20b.
  • the third length C and the fourth length D are the same, and these correspond to substantially 1 ⁇ 4 of the wavelength of the microwave propagating in the waveguide structure 8.
  • the second length B is shorter than the third length C and the fourth length D, and the first length A is the shortest of these.
  • the distance X between the slit 20a and the tube axis V is longer than the distance Y between the slit 20b and the tube axis V. That is, the ceiling surface 9 has a wider area near the recess 9a between the two first openings 14a than an area spaced from the recess 9a.
  • a turbulent electromagnetic field is generated in the waveguide structure 8 and adversely affects the formation of circularly polarized waves. It is preferable to provide a wider flat area between them. According to the present embodiment, a circular polarization with less disturbance is formed by a wider flat region provided between the two first openings 14a, and a high suction effect is obtained.
  • the distance between the two first openings 14a is 1/8 or more of the wavelength of the microwave propagating in the waveguide structure portion 8. According to the experiments by the inventors, favorable results were obtained when the two first openings 14a have a distance substantially corresponding to the shaft diameter (18 mm) of the coupling shaft 7a.
  • the second opening 14b has a cross slot shape in which two slits having the same length are orthogonal to each other at the center.
  • the major axis of each slit of the second opening 14b has an angle of 45 degrees with respect to the tube axis V.
  • the length of the major axis of each slit of the second opening 14b is equal to the third length C and the fourth length D of the first opening 14a.
  • the connecting portion 7 has the flange 7b having the above-mentioned shape, but the shape of the flange 7b is not limited to this, and can be changed as appropriate according to the specifications.
  • the first opening 14a can be provided closer to the coupling portion 7. It is also possible to provide the first opening 14a closer to the coupling portion 7 depending on the shape of the flange 7b, such as using a flange 7b having a notch with the first opening 14a.
  • the shape of the flange 7b is devised, it is possible to reinforce the joining between the coupling portion 7 and the waveguide structure portion 8 without reducing the area of the joining portion, thereby suppressing variations in products.
  • the microwave suction opening has a cross slot shape, but the microwave suction opening of the present disclosure is not limited to this. Even if the microwave suction opening has a shape other than the cross slot shape, it may have a shape capable of generating circularly polarized waves.
  • the essential condition for generating the circularly polarized wave from the waveguide structure part is that the two generally elongated openings are combined at a position shifted from the tube axis.
  • the slit constituting the microwave suction opening 14 is not limited to a rectangle. For example, even in the case of an opening having a rounded corner or an elliptical opening, it is possible to generate circularly polarized waves.
  • the corners of the opening are preferably rounded.
  • the slits included in the first opening 14a and the second opening 14b are rounded at the tip and the intersection. Has a cracked corner. That is, the two slits included in the microwave suction opening 14 have a width near the intersection that is wider than the width near the end.
  • the concave portion 9a is formed above the coupling portion 7 of the ceiling surface 9, but the waveguide structure portion 8 of the present disclosure is not limited to this.
  • a recess 9 a may be provided between the microwave suction opening 14 and the rotation center of the waveguide structure 8.
  • a convex portion projecting into the internal space of the waveguide structure 8 may be provided on the ceiling surface 9 closer to the rotation center of the waveguide structure 8 than the microwave suction opening 14.
  • the waveguide structure portion 8 is provided in a part of the ceiling surface 9 closer to the coupling portion 7 than the microwave suction opening 14 and has a step region whose height is lower than other portions of the ceiling surface 9. Good.
  • the present disclosure can be used in microwave heating apparatuses for various industrial uses such as a drying apparatus, a heating apparatus for ceramics, a garbage disposal machine, and a semiconductor manufacturing apparatus in addition to a microwave oven.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Constitution Of High-Frequency Heating (AREA)
  • Waveguide Connection Structure (AREA)
  • Electric Ovens (AREA)
PCT/JP2015/006017 2014-12-22 2015-12-04 マイクロ波加熱装置 WO2016103585A1 (ja)

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CN201580064897.7A CN107006084B (zh) 2014-12-22 2015-12-04 微波加热装置
JP2016565885A JP6503561B2 (ja) 2014-12-22 2015-12-04 マイクロ波加熱装置
EP15872162.1A EP3240363B1 (en) 2014-12-22 2015-12-04 Microwave heating device

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WO2012114369A1 (ja) * 2011-02-22 2012-08-30 三菱電機株式会社 高周波加熱装置
WO2013018358A1 (ja) * 2011-08-04 2013-02-07 パナソニック株式会社 マイクロ波加熱装置
WO2014171152A1 (ja) * 2013-04-19 2014-10-23 パナソニック株式会社 マイクロ波加熱装置

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JP2894250B2 (ja) * 1995-07-12 1999-05-24 松下電器産業株式会社 高周波加熱調理器
JP2006309949A (ja) * 2005-04-26 2006-11-09 Matsushita Electric Ind Co Ltd 高周波加熱装置
JP4677918B2 (ja) * 2006-02-09 2011-04-27 東京エレクトロン株式会社 プラズマ処理装置及びプラズマ処理方法
CN102265092B (zh) * 2008-12-25 2014-05-07 松下电器产业株式会社 微波加热烹调器
JP5467330B2 (ja) * 2009-02-27 2014-04-09 パナソニック株式会社 マイクロ波加熱装置

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Publication number Priority date Publication date Assignee Title
WO2012114369A1 (ja) * 2011-02-22 2012-08-30 三菱電機株式会社 高周波加熱装置
WO2013018358A1 (ja) * 2011-08-04 2013-02-07 パナソニック株式会社 マイクロ波加熱装置
WO2014171152A1 (ja) * 2013-04-19 2014-10-23 パナソニック株式会社 マイクロ波加熱装置

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JP6503561B2 (ja) 2019-04-24
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CN107006084B (zh) 2020-05-19
EP3240363A4 (en) 2017-12-27
JP2019079830A (ja) 2019-05-23
EP3240363B1 (en) 2020-08-26
JP6671005B2 (ja) 2020-03-25
TWI688311B (zh) 2020-03-11
TW201635856A (zh) 2016-10-01

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