JP2016118344A - Microwave heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microwave heating device capable of performing more appropriate heating control according to a state of a heating object.SOLUTION: A waveguide structure antenna in a microwave heating device guides microwaves of a transmission part to a space of a waveguide structure, and it includes a connection part capable of rotating by a rotation drive part, and a waveguide structure part connected to the connection part and for regulating a space of the waveguide structure. The waveguide structure part includes a tip opening part for radiating the microwaves transmitted in the space of the waveguide structure from the connection part toward a side wall of a power feeding chamber, and a microwave extraction opening for forming the microwaves in the space of the waveguide structure into circularly polarized waves, and for radiating toward a heating chamber. On a bottom wall of the power feeding chamber, a protrusion protruding toward the power feeding chamber is formed. A control part has a grill mode for performing heating by placing a heating object in a grill tray arranged above a placement table. In the grill mode, a first grill mode is included in which the time when the tip opening part faces the protrusion of the power feeding chamber is prolonged.SELECTED DRAWING: Figure 15B

Description

  The present disclosure relates to a microwave heating apparatus such as a microwave oven that radiates microwaves to an object to be heated and performs dielectric heating.

  In a microwave oven, which is a typical microwave heating device, microwaves radiated from a magnetron, which is a typical microwave generator, are supplied into a metal heating chamber and are placed inside the heating chamber. Dielectric heating of the heated object.

  In recent years, in a microwave oven, a highly convenient product has been put into practical use in which a bottom surface of a heating chamber on which food to be heated is placed is formed flat so that food can be easily taken in and out. In such a wide heating chamber having a flat bottom surface, it is basically preferable that the object to be heated is heated uniformly in the entire heating chamber. In order to uniformly heat the entire heating chamber, a configuration in which a rotating antenna having a waveguide structure is provided below the bottom surface of the heating chamber has been proposed (see, for example, Patent Document 1). A rotating antenna having a waveguide structure proposed in Patent Document 1 has a waveguide structure having a fan shape that is magnetically coupled to a waveguide that transmits microwaves from a magnetron. This waveguide structure is configured to form a low impedance portion in addition to the fan-shaped arc portion and radiate microwaves from the fan-shaped arc portion. By rotating the rotating antenna having the waveguide structure configured as described above below the bottom surface of the heating chamber, the heating distribution in the entire heating chamber is made uniform.

  FIG. 22 is a front cross-sectional view showing a configuration of a microwave oven having a waveguide-structured rotating antenna disclosed in Patent Document 1. As shown in FIG. As shown in FIG. 22, in the microwave oven disclosed in Patent Document 1, microwaves from a magnetron 101 that is a high-frequency oscillator are transmitted through a waveguide 102 and passed through a rotating antenna 103 having a waveguide structure. Is emitted into the heating chamber 104. The microwave radiated into the heating chamber 104 heats an object to be heated (not shown) placed on the bottom surface 108 of the heating chamber 104. The rotating antenna 103 has a fan shape in plan view and is driven to rotate by a motor 105 through a coupling shaft 109. The coupling shaft 109 guides the microwave propagating through the waveguide 102 to the rotating antenna 103 having the waveguide structure, and rotates the rotating antenna 103. In the fan-shaped waveguide structure, a low impedance portion 106 is formed in addition to the arc portion, and microwaves are radiated from the radiation port 107 in the arc portion. The rotating antenna 103 is configured such that an object to be heated in the heating chamber 104 is heated by the microwave radiated from the radiation port 107.

  Also, instead of heating the entire heating chamber, for example, when heating two foods of frozen and room temperature in the heating chamber at the same time, a function capable of locally concentrating the region where the frozen food is placed is necessary. It is. As a microwave oven having such a function that can be heated locally, a rotary antenna having a waveguide structure in which a microwave radiating port proposed in Patent Document 2 is specified is provided on the bottom surface of the heating chamber. As a configuration that can be arranged and moved on the lower side, a configuration that controls the stop position of the rotating antenna based on the internal temperature distribution detected by the infrared sensor has been proposed (see, for example, Patent Document 2).

  FIG. 23 is a front cross-sectional view showing a configuration of a microwave oven having a waveguide-structured rotating antenna disclosed in Patent Document 2. As shown in FIG. As shown in FIG. 23, in the microwave oven disclosed in Patent Document 2, the microwave from the magnetron 201 is transmitted through the waveguide 202, and inside the heating chamber 204 via the rotating antenna 203 having a waveguide structure. To be emitted. The microwave radiated into the heating chamber 204 heats an object to be heated placed on the bottom surface 208 of the heating chamber 204. The rotating antenna 203 has a quadrangular shape in a plan view, and one side of the quadrangular shape is a radiation port 207, and low impedance portions 206 are formed on the other three sides. The microwave radiated from the radiation port 207 in the moving rotating antenna 203 is radiated to a specific region of the heating chamber 204 to heat the object to be heated.

  The heating chamber 204 of Patent Document 2 is provided with an infrared temperature detector 210 as temperature distribution detection means. Based on the temperature distribution of the heating chamber 204 detected by the infrared temperature detector 210, the control means 211 controls the rotating antenna 203. The position of the radiation opening 207 is controlled.

  The rotating antenna 203 disclosed in Patent Document 2 moves on an arc while rotating inside the power supply chamber 209 formed below the bottom surface 208 of the heating chamber 204 by a waveguide motor 205 as a waveguide moving means. It is the structure to do. In the microwave oven of Patent Document 2 configured as described above, the radiation port 207 of the rotating antenna 203 moves while rotating and locally heats the low-temperature portion of the detected object to be heated.

Japanese Patent Publication No. 63-53678 Japanese Patent No. 2894250

  However, in recent years, in a microwave heating apparatus, it is required to perform more appropriate control according to the state of an object to be heated. In particular, depending on whether the food being heated is a frozen food or a food that is different from frozen food (normal temperature or refrigerated food), the temperature rise distribution in the heated object varies greatly, and uniform heating is performed. It is difficult. Thus, while it is required to perform more appropriate control according to the state of the object to be heated, in the microwave heating apparatus as described in Patent Documents 1 and 2, heating control according to the state of the object to be heated is performed. It can be said that there is still room for improvement in terms of

  This indication solves the subject in the above-mentioned conventional microwave oven, and aims at providing the microwave heating device which can perform more suitable heating control according to the state of a thing to be heated.

A microwave heating apparatus according to one embodiment of the present disclosure includes a heating chamber that configures a space above a mounting table for mounting an object to be heated, and a power supply chamber that configures a space below the mounting table. A heating unit for storing the object to be heated in the heating chamber;
A microwave generator for generating microwaves;
A transmission unit for transmitting the microwave generated by the microwave generation unit;
A waveguide structure having a space for transmitting microwaves, and a waveguide structure antenna disposed in the feeding chamber so as to radiate microwaves of the transmission unit to the heating unit;
A rotation driving unit for rotating the waveguide structure antenna;
A control unit for controlling the driving of the rotation drive unit,
The waveguide structure antenna guides the microwave of the transmission unit to the space of the waveguide structure, and is coupled to the coupling unit that can be rotated by the rotation driving unit and to the coupling unit. A waveguide structure that defines a space;
The waveguide structure includes an open end portion that radiates a microwave transmitted from the coupling portion through the space of the waveguide structure toward a sidewall of the power supply chamber, and a microwave in the space of the waveguide structure. A microwave suction opening that is circularly polarized and radiates toward the heating chamber,
On the bottom wall of the power supply chamber, a protruding portion that protrudes toward the power supply chamber is formed,
The control unit has a grill mode in which the object to be heated is placed on a grill pan arranged above the mounting table and heated.
The grill mode includes a first grill mode in which the time for the tip open portion to face the protruding portion of the power supply chamber is lengthened.

  According to the present disclosure, it is possible to provide a microwave heating apparatus that performs more appropriate heating control according to the state of an object to be heated.

Sectional drawing which shows schematic structure of the microwave oven which is the microwave heating apparatus of Embodiment 1 which concerns on this indication The perspective view which shows the electric power feeding chamber of the heating part in the microwave heating apparatus of Embodiment 1. FIG. The top view which shows the electric power feeding chamber of the heating part in the microwave heating apparatus of Embodiment 1. FIG. 3 is an exploded perspective view showing a specific example of a waveguide structure antenna in the microwave heating apparatus of the first embodiment. Perspective view showing a general rectangular waveguide The top view which shows the H surface of the waveguide which has an I-shaped opening which radiates | emits a linearly polarized wave The top view which shows the H surface of the waveguide which has an X-shaped opening which radiates | emits a circularly polarized wave Front view showing the positional relationship between the waveguide and the object to be heated Characteristic diagram by aperture of linearly polarized wave in FIG. 5A Fig. 5B Characteristic chart of circularly polarized wave opening Figure showing characteristic results of analysis under the condition of “with food” with the slit length fixed The schematic diagram which shows the example of the suction effect in the structure of the microwave oven of Embodiment 1 The schematic diagram which shows the example of the suction effect in the structure of the microwave oven of Embodiment 1 The figure which shows the planar shape of the waveguide structure part of the waveguide structure antenna which the inventor used in experiment The figure which shows the planar shape of the waveguide structure part of the waveguide structure antenna which the inventor used in experiment The top view which shows the waveguide structure part of the waveguide structure antenna in the microwave oven of Embodiment 1 Longitudinal sectional view showing arrangement in microwave oven in grill mode Top view showing the grill pan used in the grill mode Side view showing grill pan used in grill mode Longitudinal section showing grill pan used in grill mode The top view which shows the 1st rotation state of a waveguide structure antenna The perspective view which shows the 1st rotation state of a waveguide structure antenna The top view which shows the 2nd rotation state of a waveguide structure antenna The perspective view which shows the 2nd rotation state of a waveguide structure antenna The figure which shows the control flow by 1st grill mode The figure which shows direction of the waveguide structure antenna at the time of controlling based on the flow of FIG. The figure which shows the control flow by 2nd grill mode The figure which shows the direction of the waveguide structure antenna at the time of controlling based on the flow of FIG. The figure which shows the control corresponding to a 1st grill mode by changing the rotational speed of a waveguide structure antenna The figure which shows the control corresponding to 2nd grill mode by changing the rotational speed of a waveguide structure antenna Front sectional drawing which shows the structure of the microwave oven which has the rotation antenna of the waveguide structure disclosed by patent document 1 Front sectional drawing which shows the structure of the microwave oven which has the rotation antenna of the waveguide structure disclosed by patent document 2

A microwave heating apparatus according to a first aspect of the present disclosure includes a heating chamber that configures a space above a mounting table for mounting an object to be heated, and a power supply chamber that configures a space below the mounting table. A heating unit for storing the object to be heated in the heating chamber;
A microwave generator for generating microwaves;
A transmission unit for transmitting the microwave generated by the microwave generation unit;
A waveguide structure having a space for transmitting microwaves, and a waveguide structure antenna disposed in the feeding chamber so as to radiate microwaves of the transmission unit to the heating unit;
A rotation driving unit for rotating the waveguide structure antenna;
A control unit for controlling the driving of the rotation drive unit,
The waveguide structure antenna guides the microwave of the transmission unit to the space of the waveguide structure, and is coupled to the coupling unit that can be rotated by the rotation driving unit and to the coupling unit. A waveguide structure that defines a space;
The waveguide structure includes an open end portion that radiates a microwave transmitted from the coupling portion through the space of the waveguide structure toward a sidewall of the power supply chamber, and a microwave in the space of the waveguide structure. A microwave suction opening that is circularly polarized and radiates toward the heating chamber,
On the bottom wall of the power supply chamber, a protruding portion that protrudes toward the power supply chamber is formed,
The control unit has a grill mode in which the object to be heated is placed on a grill pan arranged above the mounting table and heated.
The grill mode includes a first grill mode in which the time for the tip open portion to face the protruding portion of the power supply chamber is lengthened.

  When the first grill mode is performed and microwaves are radiated from the open end of the waveguide structure antenna, the microwaves are reflected in the direction toward the heating chamber by the projecting portion of the power supply chamber, and heated. Reach the bottom of the grill pan in the room. Thereby, a to-be-heated material is indirectly heated with a microwave via the bottom face of a grill pan. In the first grill mode, since the microwave heating time is set to be long, the indirect microwave heating through the bottom surface of the grill pan can be focused on the object to be heated. it can. Thereby, since more efficient heating can be performed especially when heating an object to be heated other than frozen food, more appropriate heating control can be performed according to the state of the object to be heated.

  In the microwave heating apparatus according to the second aspect of the present disclosure, in the first grill mode according to the first aspect, the control unit causes the rotation driving unit to rotate the waveguide structure antenna. In this case, control is performed so as to include a time for the tip open portion to stop in a state of facing the protruding portion of the power supply chamber. In this way, by setting the time for rotating the waveguide structure antenna and the time for stopping without rotating and setting the time for the tip open portion to face the protruding portion of the feeding chamber, the time can be set in a simpler manner. Can be set.

  In the microwave heating apparatus according to the third aspect of the present disclosure, in the first grill mode according to the first aspect or the second aspect, the control unit is configured such that the rotation driving unit is the waveguide. When rotating the structural antenna, the rotation speed when the open end portion faces the protrusion of the power supply chamber is relatively slower than the rotation speed when the protrusion portion of the power supply chamber does not face the protrusion. Control to be. In this way, more flexible heating control can be performed by adjusting the rotation speed of the waveguide structure antenna and setting the time for the open end portion to face the protruding portion of the feeding chamber.

  In the microwave heating apparatus according to the fourth aspect of the present disclosure, the control unit according to any one of the first aspect to the third aspect uses food other than frozen food as the object to be heated. When the grill mode is selected, control including at least the first grill mode is performed. Thereby, when heating to-be-heated objects other than frozen food, more efficient heating can be performed, Therefore More suitable heating control can be performed according to the state of a to-be-heated object.

  In the microwave heating device according to the fifth aspect of the present disclosure, in the grill mode according to any one of the first to fourth aspects, the open end portion is the protruding portion of the power supply chamber. A second grill mode in which the time during which the user does not face is lengthened is included. When microwaves are radiated from the open end of the waveguide structure antenna by performing the second grill mode, the microwaves are directed to the heating chamber at locations different from the protruding portions on the side walls of the feeding chamber. By being reflected, the gap between the grill pan and the side wall of the heating chamber is reached. Thereby, a microwave reaches | attains the space above the grill pan in which a to-be-heated material is arrange | positioned, and heats to-be-heated material directly. In the second grill mode, since the microwave heating time is set to be long, direct heating by microwaves can be focused on the object to be heated. Thereby, especially when heating the to-be-heated object of frozen food, more efficient heating can be performed, Therefore More suitable heating control can be performed according to the state of a to-be-heated object.

  In the microwave heating apparatus according to the sixth aspect of the present disclosure, in the second grill mode according to the fifth aspect, the control unit causes the rotation driving unit to rotate the waveguide structure antenna. In this case, the control is performed so as to include a time for stopping in a state where the open end portion does not face the protruding portion of the power supply chamber. In this way, by providing a time for rotating the waveguide structure antenna and a time for stopping without rotating the waveguide structure antenna, and setting a long time for the open end portion not to face the protruding portion of the power supply chamber, a simpler method can be used. The time can be set.

  In the microwave heating apparatus according to the seventh aspect of the present disclosure, in the second grill mode according to the fifth aspect or the sixth aspect, the control unit is configured such that the rotation driving unit is the waveguide. When rotating the structural antenna, the rotation speed when the open end portion does not face the protrusion of the power supply chamber is relatively slower than the rotation speed when the protrusion portion of the power supply chamber faces the protrusion. Control to be. In this way, more flexible heating control can be performed by adjusting the rotation speed of the waveguide structure antenna and setting the time during which the open end portion does not face the protruding portion of the power supply chamber.

  In the microwave heating apparatus according to the eighth aspect of the present disclosure, the control unit according to any one of the fifth to seventh aspects has a grill mode in which frozen food is the heated object. When selected, control including at least the second grill mode is performed. Thereby, since more efficient heating can be performed when heating the heated object of frozen food, more appropriate heating control can be performed according to the state of the heated object.

  In the microwave heating apparatus according to the ninth aspect of the present disclosure, the side wall of the power supply chamber in any one of the first to eighth aspects spreads outward toward the heating chamber. So inclined. By inclining the side wall of the power supply chamber in this manner, the microwave radiated from the open end of the waveguide structure antenna can be more reliably directed to the heating chamber.

  In the microwave heating apparatus according to the tenth aspect of the present disclosure, the power supply chamber according to any one of the first aspect to the ninth aspect has a substantially rectangular cross section in plan view. In addition, the protrusion is provided on the bottom wall on the short side of the rectangle. By providing the protrusions in this way, the distance from the open end of the waveguide structure antenna can be adjusted to a desired distance.

  In the microwave heating apparatus according to the eleventh aspect of the present disclosure, the coupling unit according to any one of the first aspect to the tenth aspect is connected to the rotation driving unit and rotates, The waveguide structure has a coupling axis having a rotation axis that intersects the transmission direction, and the rotation center of the coupling axis is located at the center in the front-rear direction and the left-right direction in the heating chamber and the power supply chamber. With such an arrangement, the object to be heated can be heated more uniformly by the microwave radiated from the waveguide structure antenna.

  In the microwave heating apparatus according to the twelfth aspect of the present disclosure, the microwave suction opening according to any one of the first aspect to the eleventh aspect is an opening where at least two long holes intersect. The waveguide structure is formed at a position biased to one side with respect to the tube axis extending in the transmission direction in the waveguide structure. Thereby, circularly polarized waves can be reliably radiated from the microwave suction opening to the heating chamber.

  In the microwave heating apparatus according to a thirteenth aspect of the present disclosure, the waveguide structure unit according to any one of the first aspect to the twelfth aspect includes a plurality of the microwave suction openings. The plurality of microwave suction openings are arranged symmetrically with respect to a tube axis extending in the transmission direction in the waveguide structure. Thereby, the fall of the heating temperature in the center area | region of a heating chamber can be suppressed.

  Hereinafter, a preferred embodiment of a microwave heating apparatus according to the present disclosure will be described with reference to the accompanying drawings. In the microwave heating apparatus of the following embodiment, a microwave oven will be described. However, the microwave oven is an example, and the microwave heating apparatus of the present disclosure is not limited to the microwave oven, and uses dielectric heating. And a microwave heating device such as a garbage processing machine or a semiconductor manufacturing device. Further, the present disclosure is not limited to the specific configurations of the following embodiments, and configurations based on similar technical ideas are included in the present disclosure.

(Embodiment 1)
FIG. 1 is a diagram illustrating a schematic configuration of a microwave oven that is the microwave heating apparatus according to the first embodiment of the present disclosure, and is a cross-sectional view of the microwave oven as viewed from the front side. In the following description, the left and right direction of the microwave oven means the left and right direction in FIG. 1, and the front and rear direction means a direction perpendicular to the paper surface in FIG. 1 and connecting the front side and the back side of the apparatus. .

  As shown in FIG. 1, the microwave oven 1 according to the first embodiment includes a heating unit 2, a magnetron 3, a waveguide 4, a waveguide structure antenna 5, and a mounting table 6. The heating unit 2 constitutes a heating chamber 2a that constitutes a space above the placing table 6 for placing food (not shown) that is a typical object to be heated, and a space below the placing table 6. Power supply chamber 2b. The magnetron 3 is an example of a microwave generation unit that generates a microwave. The waveguide 4 is an example of a transmission unit that transmits the microwave generated in the magnetron 3 to the heating unit 2. The waveguide structure antenna 5 is configured to radiate the microwave in the waveguide 4 serving as a transmission unit into the heating unit 2 and is provided in the space of the power supply chamber 2 b below the mounting table 6. .

  The mounting table 6 in the heating unit 2 has a flat surface on which food that is an object to be heated is placed. The mounting table 6 covers the entire power supply chamber 2b provided with the waveguide structure antenna 5, thereby closing the power supply chamber 2b so that the waveguide structure antenna 5 is not exposed in the heating chamber 2a. It constitutes the bottom surface of 2a. Since the upper surface (mounting surface) of the mounting table 6 is formed flat, it is easy for the user to put in and out food, and the dirt and the like attached to the mounting table 6 can be easily wiped off. As the material for the mounting table 6, a material such as glass or ceramic that easily transmits microwaves is used. In this way, by using a material that easily transmits microwaves as the material for the mounting table 6, the microwave radiated from the waveguide structure antenna 5 in the feeding chamber 2 b below the mounting table 6 can be used. It is the structure which propagates reliably to the space in the upper heating chamber 2a.

  The waveguide structure antenna 5 includes a coupling portion 7 that extracts a microwave from the inside of the waveguide 4, and a waveguide structure portion 8 that has a box-shaped waveguide structure to which the microwave extracted by the coupling portion 7 is guided. Have The coupling part 7 is composed of a coupling shaft 7a and a flange 7b. The coupling shaft 7a is connected to a motor 15 that is a rotation driving unit, and the waveguide structure unit 8 joined to the coupling unit 7 is rotationally controlled by a control signal from a control unit 17 described later. That is, the waveguide structure antenna 5 is rotationally driven around the coupling axis 7a of the coupling portion 7, and the stop position, the rotation period, the rotation speed, and the like are controlled. The coupling portion 7 is formed of a metal, for example, an aluminum-plated steel plate, and the connection portion of the motor 15 connected to the coupling portion 7 is formed of, for example, a fluororesin.

  As shown in FIG. 1, the coupling shaft 7a of the coupling portion 7 passes through an opening that communicates the waveguide 4 that is a transmission portion and the power supply chamber 2b, and the coupling shaft 7a is between the opening that penetrates. A gap having a predetermined interval, for example, a gap of 5 mm or more is provided. The coupling shaft 7 a passes through the opening, and thus the microwave from the waveguide 4 is efficiently guided to the waveguide structure portion 8 of the waveguide structure antenna 5.

  In the microwave oven 1 according to the first embodiment, a motor 15 as a rotation driving unit is joined to a coupling unit 7 of the waveguide structure antenna 5, and the microwave from the waveguide structure antenna 5 is rotated by the rotation of the coupling unit 7. The radiation direction of is changed. Moreover, the microwave oven 1 of Embodiment 1 is provided with the infrared sensor 16 above the side surface of the heating chamber 2a. The infrared sensor 16 is configured to divide the heating chamber 2a into a plurality of regions, detect the internal temperature state of each region, and transmit a detection signal (detection result) to the control unit 17. Based on the detection signal from the infrared sensor 16, the control unit 17 drives and controls the magnetron 3 that is a microwave generation unit and the motor 15 that is a rotation drive unit. The infrared sensor 16 is an example of a state detection unit that detects the internal temperature state of the heating chamber 2a, in particular, the state of the food, and detects the surface temperature of the food as the state of the food. As described above, in the microwave oven 1 according to the first embodiment, the control unit 17 performs the oscillation control of the magnetron 3 and the rotation control of the motor 15 based on the detection signal from the infrared sensor 16.

  In addition, although Embodiment 1 demonstrates the case where the infrared sensor 16 which detects the temperature of a foodstuff is used as an example of a state detection part, this indication is not limited to this structure. For example, the present disclosure also includes a configuration in which a weight sensor that detects the weight (center of gravity) of food or an image sensor that acquires an image of food is used as the state detection unit. Or it is the structure which does not use such a state detection part, Comprising: Even if it is the drive control based on the preset operation | movement, it is included in this indication. For example, a plurality of programs that can be selected by the user are stored in the microwave oven 1, and the control unit 17 drives and controls the motor 15 based on the program selected by the user to control the rotational position of the waveguide structure antenna 5. May be performed.

  FIG. 2A is a perspective view showing the feeding chamber 2b of the heating unit 2 provided with the waveguide structure antenna 5, and shows a bottom surface portion of the heating unit 2 with the mounting table 6 removed. FIG. 2B is a plan view showing the power supply chamber 2b of FIG. 2A. As shown in FIGS. 2A and 2B, a waveguide structure antenna 5 is provided in a power supply chamber 2 b that is disposed immediately below the heating chamber 2 a and is separated from the heating chamber 2 a by the mounting table 6. The rotation center G of the coupling shaft 7a in the waveguide structure antenna 5 is located at the center in the front-rear direction and the left-right direction of the power supply chamber 2b. It is a position directly under the center of

  As shown in FIGS. 2A and 2B, the power feeding space constituted by the bottom surface 11 of the power feeding chamber 2 b and the lower surface of the mounting table 6 is a center line J extending in the front-rear direction of the power feeding chamber 2 b including the rotation center G of the coupling portion 7. (See FIG. 2B). Projections 18 (projections 18a and 18b) projecting from the bottom wall 11 of the power supply chamber 2b toward the power supply chamber 2b are formed. The protruding portion 18a is provided so as to protrude from the bottom wall 11 so as to form the left side wall 2c, and the protruding portion 18b is provided so as to protrude from the bottom wall 11 so as to form the right side wall 2c. Yes. A magnetron 3 is provided below the right protrusion 18b. The purpose of providing the protruding portion 18b is also to secure a space for arranging the magnetron 3. The microwave from the output end 3a of the magnetron 3 is transmitted through the waveguide 4 which is a transmission section formed immediately below the power supply chamber 2b, and is transmitted to the waveguide structure section 8 having a waveguide structure via the coupling section 7. It is guided and radiated into the power supply chamber 2b.

  The side wall 2c that forms the side surface of the power supply space of the power supply chamber 2b is formed with an inclined surface that faces obliquely upward, that is, an inclined surface that is inclined so as to spread outward toward the heating chamber 2a. The side wall 2c formed in this manner is configured to reflect the microwave radiated from the waveguide structure antenna 5 in the horizontal direction and reflect it to the upper heating chamber 2a.

  The power feeding chamber 2b has a substantially rectangular cross section in plan view, and protrudes from the bottom wall 11 so as to form a side wall 2c on the short side (left and right sides in the first embodiment) of the rectangle. A protrusion 18 is provided. The four corners in the rectangle correspond to the corners 22a, 22b, 22c, and 22d of the power supply chamber 2b. A protrusion 18a is formed between the corner 22a and the corner 22d, and a protrusion 18b is formed between the corner 22b and the corner 22c of the power supply chamber 2b.

  FIG. 3 is an exploded perspective view showing a specific example of the waveguide structure antenna 5. As shown in FIG. 3, the waveguide structure 8 having a substantially square shape in plan view in the waveguide structure antenna 5 is a waveguide in which three sides of the four sides are linear and the remaining one side is formed in an arc shape. It has a tube structure. One side of the arcuate shape of the waveguide structure 8 is open and serves as an open end portion 13 that radiates microwaves transmitted through the waveguide structure 8. The waveguide structure portion 8 includes an upper wall surface 9 that faces the lower surface of the mounting table 6, three side wall surfaces 10a, 10b, and 10c connected to the upper wall surface 9, and three side wall surfaces 10a, 10b, and 10c. A low-impedance portion 12 extending horizontally outward to face the bottom surface of the power supply chamber 2b. A joint portion to which the coupling portion 7 is joined is formed on the lower surface of the upper wall surface 9 of the waveguide structure portion 8.

  The side wall surfaces 10a, 10b, and 10c in the waveguide structure 8 are formed so as to close three sides around the waveguide structure 8 having a box-shaped waveguide structure. Leakage is suppressed. In the waveguide structure portion 8, a tip opening portion 13 is formed at a position farthest from the coupling portion 7 which is the remaining one. From the opening of the tip opening portion 13, the microwave transmitted from the coupling portion 7 through the waveguide structure portion 8 is radiated in the horizontal direction. The low impedance portions 12 extending horizontally outward from the lower ends of the three side wall surfaces 10a, 10b, and 10c are formed in parallel so as to face the bottom surface 11 of the power supply chamber 2b with a slight gap. In the waveguide structure portion 8 in the first embodiment, an insulating resin spacer (not shown) is attached to a part of the low impedance portion 12 in order to secure a gap with the bottom surface 11 of the power supply chamber 2b. A holding part 19 is formed for this purpose.

  As shown in FIG. 3, each low impedance part 12 is formed with a plurality of slits 12a. Each slit 12a is formed to extend in a direction orthogonal to the side wall surfaces 10a, 10b, and 10c connected to the low impedance portion 12 in which each slit 12a is formed. Thus, since the low impedance part 12 extended from the lower end of each side wall surface 10a, 10b, 10c is formed, from the clearance gap between side wall surface 10a, 10b, 10c and the bottom face 11 of the electric power feeding chamber 2b, side wall surface 10a, Microwave leakage in the direction orthogonal to 10b and 10c is greatly suppressed. On the other hand, the plurality of slits 12a formed in the low impedance portion 12 form a periodic structure by being arranged at a predetermined interval, and suppress leakage of microwaves in a direction parallel to the side wall surfaces 10a, 10b, and 10c. . This predetermined interval is appropriately determined according to the wavelength transmitted through the waveguide structure 8.

  As described above, in the waveguide structure portion 8 of the waveguide structure antenna 5, only one side of the substantially rectangular upper wall surface 9 is formed in an arc shape, and the lower portion of the arc-shaped edge portion is widely opened. The leading end opening 13 is formed. In addition, in the microwave oven of Embodiment 1, although demonstrated in the example in which the front-end | tip open | release part 13 was formed in circular arc shape, this indication is not limited to this shape, It is linear and curved shape, Also good.

  In the microwave oven according to the first embodiment, as shown in FIG. 3, the upper wall surface 9 is formed with microwave suction openings 14 which are a plurality of openings having a special function as will be described later. The waveguide structure antenna 5 configured as described above is configured such that the microwave inside the waveguide structure portion 8 is controlled and radiated from the tip opening portion 13 and the plurality of microwave suction openings 14.

  As shown in the exploded perspective view of FIG. 3, the waveguide structure antenna 5 has a coupling portion 7 as a rotation center fixed to a waveguide structure portion 8 having a box-shaped waveguide structure. In the configuration of the first embodiment, the flange 7b formed in the coupling portion 7 is joined (caulking, spot welding, screw tightening) to the upper wall surface 9a of the waveguide structure portion 8 as a joining portion. In addition, as joining of the coupling | bond part 7 and the waveguide structure part 8, it is also possible to join the coupling shaft 7a directly to the upper wall surface 9a using joining means, such as welding.

  The microwave heating apparatus according to the present disclosure is based on various experiments conducted by the inventors, and the waveguide structure antenna 5 configured as described above has a special waveguide structure as will be described later. It becomes possible to locally heat the object and to make the heating distribution in the heating chamber uniform. In the microwave oven that is the microwave heating apparatus according to the first embodiment of the present disclosure, in particular, in the central region of the heating chamber immediately above the rotation center in the waveguide structure antenna, the heating can be performed with high efficiency. It has the structure which can suppress the nonuniformity of the heating temperature of a center area | region. Below, the special waveguide structure in the microwave oven which is the microwave heating device of Embodiment 1 is demonstrated.

[Waveguide structure]
First, in order to understand the waveguide structure, a general waveguide 300 will be described using FIG. As shown in FIG. 4, the simplest and general waveguide 300 is a rectangular waveguide made of a rectangular parallelepiped having a certain rectangular cross section (width a, height b) extended in the transmission direction Z. A wavelength in free space of the microwave when the lambda _0, the width a and height b of the waveguide 300, from _{λ 0>a> λ 0/} 2, and b <λ _0/2 in the range It is known to transmit microwaves in the TE10 mode through the waveguide 300 by selecting.

  The TE10 mode is a transmission in an H wave (TE wave; Transverse Electric Wave) in which only a magnetic field component exists in the microwave transmission direction Z in the waveguide 300 and no electric field component exists. Refers to the mode.

Here, prior to description of the guide wavelength λg in the waveguide 300 will be described wavelength lambda ₀ of the free space. The wavelength λ _{0 of the} free space can be obtained by the equation λ ₀ = c / f. In this equation, c is the speed of light, and is constant at about 2.998 × 10 ⁸ [m / s]. On the other hand, f is an oscillation frequency, and in the case of a microwave oven, it has a width of 2.4 to 2.5 [GHz] (ISM band). Since the oscillation frequency f changes depending on magnetron variations and load conditions, the wavelength λ _{0 in} free space also changes. Accordingly, the wavelength λ _{0 of the} free space changes from a minimum of 120 [mm] (at 2.5 GHz) to a maximum of 125 [mm] (at 2.4 GHz).

In the case of the waveguide 300 used for a microwave oven, the width a of the waveguide 300 is generally 80 to 100 mm and the height b is 15 to 15 in consideration of the range of the wavelength λ _{0 in} free space. Often selected from within a range of about 40 mm. At this time, in the waveguide 300 shown in FIG. 4, the wide surface 301 that is the upper and lower surfaces is called the H surface in the sense that the magnetic field spirals in parallel, and the narrow surface 302 that is the left and right surfaces is used as the electric field. It is called the E plane in the meaning of a parallel plane.

If the microwave from the magnetron, which is the microwave generation unit, is λ ₀ and the wavelength of the microwave when transmitting through the waveguide is the guide wavelength λg, λg = λ ₀ / √ (1− (λ ₀ / (2 × a)) ² ). Accordingly, the guide wavelength λg varies depending on the dimension of the width a of the waveguide 300, but is independent of the dimension of the height b. In the TE10 mode, the electric field is zero at both ends (E plane) 302 of the waveguide 300 in the width direction W, and the electric field is maximum at the center in the width direction W.

  The same idea as the waveguide 300 shown in FIG. 4 can also be applied to the waveguide structure antenna 5 in the first embodiment shown in FIGS. The upper wall surface 9 of the waveguide structure antenna 5 and the bottom surface 11 of the feeding chamber 2b are H planes. The opposing side wall surfaces 10a and 10c in the waveguide structure antenna 5 are E surfaces. The side wall surface 10 b facing the tip open portion 13 is a reflection end for reflecting all the microwaves in the waveguide structure antenna 5 in the direction of the tip open portion 13. Specifically, the waveguide structure antenna 5 in the first embodiment has a waveguide width (a) of 106.5 mm.

  As described above, a plurality of microwave suction openings 14 are formed on the upper wall surface 9 which is the H surface of the waveguide structure antenna 5. In the microwave suction opening 14, the tube axis (the center line in the width direction of the H surface of the waveguide is generally referred to as the tube axis) that is the center line V extending in the transmission direction in the waveguide structure of the waveguide structure antenna 5. ), The two first openings 14a are arranged in line symmetry, and similarly, the two second openings 14b are arranged in line symmetry. The opening portions of the first opening 14a and the second opening 14b are formed so as not to cross the tube axis (center line V). As described above, the opening portions of the first opening 14a and the second opening 14b are arranged to be biased to one side so as not to cross the tube axis (V) of the H surface in the waveguide structure antenna 5, whereby the first It becomes the structure which can radiate | emit circularly polarized wave reliably from the opening 14a and the 2nd opening 14b. The direction of rotation of the electric field differs depending on which region of the tube axis (V) in the H plane the opening portions of the first opening 14a and the second opening 14b are formed. : Clockwise) or left-handed polarization (CCW: counter clockwise). Since circularly polarized waves are radiated from the first opening 14a and the second opening 14b, a vortex electric field is radiated from each opening portion, so that an even electric field distribution can be formed.

  In the first embodiment, the example in which the opening portions of the first opening 14a and the second opening 14b are arranged so as not to cross the tube axis (V) has been described. Even when the tube axis (V) is straddled, it becomes a microwave suction opening capable of emitting circularly polarized waves. However, the circularly polarized wave in this case is radiated as a distorted circle, but it is possible to make the temperature distribution in the heating chamber uniform.

[Circularly polarized radiation structure]
Next, circular polarization will be described. Circular polarization is a technique widely used in the fields of mobile communications and satellite communications. Familiar use examples include ETC (Electronic Toll Collection System) “non-stop automatic toll collection system”. Circular polarization is a microwave in which the polarization plane of the electric field rotates with respect to the traveling direction according to time. When circularly polarized waves are formed, the direction of the electric field continues to change with time, and the magnitude of the electric field strength does not change. If this circularly polarized wave is applied to a microwave heating device, it is expected that the object to be heated will be heated evenly, particularly in the circumferential direction of the circularly polarized wave, as compared with the conventional microwave heating by linearly polarized wave. The As described above, circularly polarized waves are classified into two types, that is, right-handed polarized waves and left-handed polarized waves from the direction of rotation. In the field of microwave heating devices, either type is circularly polarized. However, it is possible to form a uniform heating distribution.

  Since circularly polarized waves are primarily used in the field of communications, they are generally discussed in terms of so-called traveling waves that do not return reflected waves because they are intended for radiation into open spaces. On the other hand, in the microwave oven 1 of Embodiment 1, since the heating unit 2 is a closed space shielded from the outside, there is a possibility that a reflected wave is generated and synthesized with a traveling wave to become a standing wave. . However, since the food absorbs the microwave, the reflected wave becomes small, and at the moment when the microwave is radiated from the microwave suction opening 14, the balance of the standing wave is lost and the standing wave is stabilized again. It is considered that a traveling wave is generated until it returns to. Therefore, by making the microwave suction opening 14 have a shape that can radiate circularly polarized waves, it is possible to utilize the above-described features of circularly polarized waves, and the heating distribution in the heating chamber 2a can be made more uniform. .

  Here, there are some differences between the open space communication field and the closed space heating field, so a description will be added. In the communication field, we want to send and receive only the necessary information while avoiding mixing with other microwaves, so the transmitting side is limited to either right-handed polarization or left-handed polarization, and the receiving side also adjusts accordingly. The optimum receiving antenna will be selected.

  On the other hand, in the field of heating, instead of a receiving antenna having directivity, a heated object such as food with no directivity receives microwaves, so only microwaves are irradiated to the entire heated object. Is important. Therefore, in the field of heating, there is no relationship between right-handed polarized waves and left-handed polarized waves, and there is no problem even if a plurality of openings are formed and right-handed polarized waves and left-handed polarized waves are mixed.

[Local heating by waveguide structure antenna]
Hereinafter, with respect to the microwave suction opening 14 of the waveguide structure antenna according to the first exemplary embodiment, the microwave in the waveguide structure is sucked out as the object to be heated such as food is closer to the object to be heated. The suction effect of performing local heating will be described.

  First, the suction effect will be described. Using CAE, linear polarization and circular polarization were compared to determine how much the distance between the microwave suction opening 14 and food is related to the amount of microwave radiation. FIG. 5A is a plan view showing the H-plane of a waveguide 400 having an I-shaped opening that radiates linearly polarized waves, and FIG. 5B shows a waveguide 500 having an X-shaped opening that radiates circularly polarized waves. It is a top view which shows the H surface. FIG. 5C is a front view showing the positional relationship between the waveguide 400 or 500 and the food F to be heated.

  As shown in FIG. 5A, the opening 401 for generating linearly polarized waves intersects the tube axis (the center line V in the width direction) extending in the transmission direction in the waveguide 400 and is linear (I-shaped) over both sides thereof. It is an opening. As shown in FIG. 5B, the two openings 501 that generate circularly polarized waves are X-shaped openings and are arranged symmetrically with respect to the tube axis (V) of the waveguide 500. Accordingly, each of the openings 401 and 501 has a symmetrical opening shape with respect to the center line V in the width direction of each waveguide 400 or 500. Note that each of the openings 401 or 501 has a slit width of 10 mm and a slit length of L mm. In this configuration, analysis was performed for the case where the food F was not arranged (“no food”) and the case where the food F was arranged (“food present”) as shown in FIG. 5C. When the food F is arranged as shown in FIG. 5C, the height of the food F is constant at 30 mm, the area of the bottom surface of the food F is two types (100 mm square and 200 mm square), and the material of the food F is selected. Three types (frozen beef, refrigerated beef, water), the distance D from the opening surface of the waveguide 400 or 500 to the food F was measured as a parameter.

  First, in order to use the amount of microwave radiation from the opening in the case of “no food” as a reference, the change in the amount of radiation due to the slit length L of the opening in the case of “no food” is shown in FIG. 6A and FIG. 6B. Shown. 6A shows the characteristics due to the linearly polarized aperture 401 in FIG. 5A, and FIG. 6B shows the characteristics due to the circularly polarized aperture 501 in FIG. 5B. 6A and 6B, the horizontal axis is the slit length L [mm] of the opening, and the vertical axis is radiated from the opening 401 or 501 when the power transmitted through the waveguide is 1.0. The amount of radiation [W].

  For comparison with the case of “with food”, a slit length L of 45.5 mm was selected in the graph of FIG. 6A, and a slit length L of 46.5 mm was selected in the graph of FIG. 6B. Regarding the selection of the slit length L, in the case of “no food”, the slit length L that radiates the same amount (1/10 of the power transmitted through the waveguide) (L in which the vertical axis of the graph is 0.1) ) Was selected.

  Next, FIG. 7 shows the result of the analysis by fixing the slit length L to the selected length and analyzing the conditions under the condition “with food”. As the types of food, three types of frozen beef, refrigerated beef, and water were used, and the area of the bottom surface of the food was analyzed using two types of 100 mm square and 200 mm square. In each graph shown in FIG. 7, the horizontal axis is the distance D [mm] from the food F to the opening surface, and the vertical axis is the relative value when the radiation amount at no load is 1.0. The amount of radiation. That is, it indicates how many times the amount of radiation is increased in the case of “with food” as compared with the case of “without food”. Indicates whether to suck out. In each graph shown in FIG. 7, a broken line indicates a linearly polarized wave (I-shaped opening 401), and a solid line indicates a circularly polarized wave (two X-shaped openings 501). In any of the openings 401 and 501, it can be understood that the circularly polarized wave has a larger radiation amount than the linearly polarized wave, and in particular, there is a difference of about twice in a practical distance where the distance D is 20 mm or less. Therefore, regardless of the type of food F and the area of the food F, it is clear that the circularly polarized wave has a higher microwave sucking effect than the linearly polarized wave.

  Looking in detail, regarding the type of food F, especially when the distance D is 10 mm or less, frozen beef with a smaller dielectric constant and dielectric loss has a larger suction effect, and water with a larger dielectric constant and dielectric loss. However, the suction effect is small. Further, in the case of refrigerated beef and water, when the distance D is large, the radiation amount is reduced to 1 or less particularly in the case of linearly polarized waves. It is considered that this is because the microwave reflected by the food F returns and cancels out.

  In addition, about the area of the bottom face of the food F, since the radiation amount of a microwave hardly changes with 100 mm square and 200 mm square, it is thought that there is little influence on the sucking effect of a microwave.

  The opening shape for generating circularly polarized waves is not limited to the X shape. The inventor examined the conditions of the aperture that can radiate circularly polarized waves by changing the aperture shape in various ways. As a result, as a preferable condition for generating circularly polarized waves, the opening is shifted from the center (center line V) in the width direction of the waveguide, and the opening of the long hole (slit) where the opening shape intersects Including. Further, according to the inventors' experiments, it is understood that circularly polarized microwaves can be efficiently radiated from an X-shaped opening, and this X-shaped opening has a high suction effect. It was.

  8A and 8B are schematic diagrams illustrating an example of a suction effect in the configuration of the microwave oven according to the first embodiment. FIG. 8A shows a case where the food F is arranged in the vicinity immediately above the coupling portion 7, and FIG. 8B shows that the food F is removed from the center of the heating chamber 2 a, the waveguide structure antenna 5 is rotated, and the tip opening portion 13 is moved. This is a case where the food is arranged in the direction of the food F. Therefore, in the state shown to FIG. 8A and FIG. 8B, the distance from the coupling | bond part 7 to the foodstuff F differs.

  In the state shown in FIG. 8A, since the food F is close to the first opening 14a of the microwave suction opening 14, a sucking effect is generated in the first opening 14a. That is, most of the microwaves traveling from the coupling portion 7 to the tip opening portion 13 are emitted from the first opening 14a as microwaves directly irradiating the food F, and the food F disposed in the central region Even heating is uniform.

  On the other hand, in the state shown in FIG. 8B, since the food F is separated from the microwave suction opening 14, no suction effect is generated in the microwave suction opening 14. That is, most of the microwaves heading from the coupling part 7 to the tip opening part 13 are microwaves heading for the food F from the tip opening part 13 arranged at an appropriate position by turning the waveguide structure antenna 5. Is radiated and directly and efficiently heats the food F disposed locally by linearly polarized waves.

  As described above, the microwave suction opening 14 according to the first embodiment increases the amount of microwave radiation only when food is placed near the microwave suction opening 14, and is located away from the microwave suction opening 14. When it is arranged, it has a special control function of reducing the amount of microwave radiation.

[Uniform heating with waveguide antenna]
Hereinafter, in the microwave oven that is the microwave heating apparatus according to the first embodiment of the present disclosure, the waveguide structure antenna is made uniform in the heating distribution in the heating chamber, in particular, heating just above the rotation center in the waveguide structure antenna. An efficient configuration for suppressing the lowering of the heating temperature in the central region, which occurs when an object to be heated is placed in the central region of the chamber, and making the heating distribution uniform will be described. The inventor conducted experiments on the heat distribution using waveguide structure antennas having various shapes of waveguide structures, and found the optimum waveguide structure. About the waveguide structure used in the measurement experiment explain.

  FIG. 9 is a diagram showing a planar shape of the waveguide structure portion of the waveguide structure antenna used by the inventors in the experiment. 9A to 9C, each of the waveguide structures is provided with a plurality of microwave suction openings arranged symmetrically with respect to a center line V (tube axis) parallel to the transmission direction. ing. Each microwave suction opening has two first openings and two second openings that are symmetrical with respect to the center line. In the waveguide structure shown in FIGS. 9A to 9C, only the shape of the first opening is changed, and the second opening is formed in the same shape. In FIG. 9, reference numeral 7 indicates a coupling portion, and reference numeral G indicates a central axis (rotation center) of the coupling portion 7.

  In the waveguide structure 600 shown in FIG. 9A, each of the first opening 614a and the second opening 614b of the microwave suction opening has two long holes (slits) of the same length at the respective centers. It has an X shape that is orthogonal. Further, the major axis of each elongated hole is inclined 45 degrees with respect to the center line V parallel to the transmission direction.

  The waveguide structure 700 shown in FIG. 9B is different from the waveguide structure 600 shown in FIG. 9A in that only one first opening 714a is formed.

  The difference between the waveguide structure unit 800 shown in FIG. 9C and the waveguide structure unit 600 shown in FIG. 9A is that the coupling portion 7 from the intersecting portion in the long hole constituting the first opening 814a. The opening part extending in the direction of is closed, and each first opening 814a is formed in a T shape. That is, the waveguide structure portion 800 shown in FIG. 9C has a configuration in which no microwave suction opening is formed in the vicinity of the coupling portion 7.

  A frozen okonomiyaki serving as an object to be heated is placed at the center of the mounting table 6 (center of the heating chamber 2a) by a microwave oven of a waveguide antenna having the waveguide structure shown in FIG. And verified by CAE.

  As a result, when the first opening 614a, which is a large microwave suction opening, is close to and formed opposite to the coupling portion 7 as in the waveguide structure 600 shown in FIG. It was found that the circularly polarized waves output from the openings interfere with each other, and the heating temperature in the central region near the coupling portion becomes abnormally low. Like the waveguide structure 700 shown in FIG. 9B, only one first opening 714a, which is a large opening, is formed near the coupling portion 7, and the microwave suction opening is set to the center line V ( By forming asymmetric with respect to the tube axis), it was possible to suppress a decrease in the heating temperature in the central region of the heating chamber directly above the coupling portion 7. Further, as in the waveguide structure 800 shown in FIG. 9C, in the vicinity of the coupling portion 7, an opening portion extending in the direction of the coupling portion 7 from the intersecting portion of the first opening 814 a that is opposed is eliminated. Thus, it was possible to suppress a decrease in the heating temperature in the central region of the heating chamber.

As described above, in the waveguide structure antenna, by forming a large opening in the vicinity of the coupling portion so as not to face, a decrease in the heating temperature in the central region of the heating chamber is suppressed, and the heating distribution of the heating chamber is reduced. It was understood that the configuration can be made uniform.
Furthermore, the inventor conducted various experiments on the shape of the microwave suction opening to be formed in the waveguide structure of the waveguide structure antenna, and found a configuration capable of further uniforming the heating distribution.

  Since the first opening 814a of the waveguide structure 800 shown in FIG. 9C has a T-shape without an opening extending from the intersecting portion in the direction of the coupling portion 7, an X-shaped opening is formed. The circularly polarized wave having a distorted shape, which is different from the beautiful circularly polarized wave formed by the above, is radiated. For this reason, it is possible to suppress a decrease in the heating temperature in the central region of the heating chamber, but this is not a preferable circularly polarized shape in terms of achieving a uniform heating distribution in the heating chamber. Therefore, in order to suppress the interference of the circularly polarized waves output from the opening portions facing each other and to make the circularly polarized wave as close to the circle as possible, (a) and (b) of FIG. As shown in FIG. 4, the configuration in which the opening portion extending from the intersecting portion in the direction of the coupling portion 7 has a short length in the long hole forming the first opening was studied. That is, in the first opening, one of the two long holes (slits) is formed short and only the opening extending from the intersecting portion in the direction of the coupling portion 7 is shortened to a substantially X-shaped configuration. Various experiments were conducted. As a result, with respect to uniform heating distribution, a configuration having a substantially X-shaped opening gave a preferable result as compared to an opening having a T-shape. In the first opening formed in this way, the interference of the circularly polarized waves output from the opening portions facing each other can be suppressed, and the above-described suction effect is enhanced, so that the heating temperature in the central region of the heating chamber is reduced. It was possible to suppress the decrease and make the heating distribution uniform.

  In the first opening, the length extending from the intersecting portion in the direction of the coupling portion 7 is set so that the output does not interfere with the microwaves radiated from the facing opening portion, and the specification (output) of the microwave oven It is set appropriately according to Hereinafter, the waveguide structure portion in which the first opening is formed in a substantially X shape will be described in detail.

  FIG. 10 is a diagram showing a planar shape of the waveguide structure portion of the waveguide structure antenna used in the experiment by the inventors, and the waveguide structure portion has a substantially X-shaped first opening.

  In the waveguide structures 900A and 900B shown in FIGS. 10A and 10B, the opening portion extending from the intersecting portion in the direction of the coupling portion 7 is formed short in the long hole constituting the first opening 914a. That is, in the elongated hole extending in the direction of the coupling portion 7 in the first opening 914a, the length of the opening portion extending from the intersection portion in the direction of the coupling portion 7 is formed shorter than the length of the opening portion extending in the opposite direction from the intersection portion. ing. Therefore, in the waveguide structure portion 900A shown in FIG. 10A, the vicinity of the coupling portion on the upper wall surface is formed flat. On the other hand, in the waveguide structure portion 900B shown in FIG. 10B, a concave joint region is formed at the joint portion of the coupling portion 7 (fixed portion of the flange 7b). Therefore, the distance between the surface of the joining region with the coupling portion 7 on the upper wall surface of the waveguide structure 900B and the lower surface of the mounting table is longer than that of other portions on the upper wall surface.

  Using the microwave oven of the waveguide structure antenna having the waveguide structure shown in FIG. 10, similarly, the frozen okonomiyaki is placed at the center of the heating chamber 2a as the object to be heated, and the heating experiment is performed under the same heating conditions. Verification was performed by CAE. In the waveguide structure shown in FIGS. 10A and 10B, only the shape of the joint portion of the coupling portion 7 on the upper wall surface is changed, and the first opening 914a and the second opening 914b have the same shape. Formed. In FIG. 10, reference numeral 7 indicates a coupling portion, and reference numeral G indicates a rotation center of the coupling portion 7.

  As a result, in the waveguide structure shown in FIG. 10A, the opposed first openings 814a extend from the intersecting portion in the direction of the coupling portion 7 as shown in FIG. 9C. Compared to the case where the opening portion is eliminated, the first opening 814a has a substantially X shape, so that interference with circularly polarized waves output from the facing opening portion is suppressed and a circular polarization close to a circular shape is achieved. It becomes the structure which can generate | occur | produce a wave. The first opening 814a formed in this manner has a higher suction effect and can radiate a large amount of microwaves to food disposed in the central region of the heating chamber. A decrease in temperature could be suppressed. Furthermore, as shown in FIG. 10B, the upper wall surface of the waveguide structure portion 900B is formed with a recess in the bonding region corresponding to the bonding portion of the coupling portion 7, so that the heating chamber 2a It turned out that the fall of the heating temperature in a center area | region can be suppressed more.

  In the present disclosure, a waveguide structure antenna in a microwave oven, which is a microwave heating device, is configured based on the findings from various experiments as described above by the inventors. The microwave oven according to the first embodiment described below is an exemplification showing a specific configuration of the microwave heating device of the present disclosure. In the present disclosure, various microwave ovens are used based on the above knowledge according to the specifications of the microwave heating device. Variations are possible.

  FIG. 11 is a plan view showing the waveguide structure portion 8 of the waveguide structure antenna in the microwave oven of the first embodiment.

  The waveguide structure portion 8 of the waveguide structure antenna in the microwave oven according to the first embodiment is the upper wall surface 9 of the waveguide structure portion 8 with the waveguide structure according to the first embodiment, as shown in FIG. A plurality of microwave suction openings 14 are formed. The plurality of microwave suction openings 14 formed in the upper wall surface 9 have two types of shapes, and are configured by a first opening 14a having a large opening and a second opening 14b having a small opening. Each of the opening shapes of the first opening 14a and the second opening 14b has a substantially X shape in which long holes (slits or slots) are crossed so as to be orthogonal.

  As shown in FIG. 11, the center points P1 and P2 of the first opening 14a and the second opening 14b are connected to the center line V in the width direction W of the upper wall surface 9 (parallel to the transmission direction Z in the waveguide structure portion 8). By arranging them at positions shifted from the center line (tube axis), each microwave suction opening 14 has a circularly polarized radiation structure capable of emitting circularly polarized waves. Here, the center point P1 of the first opening 14a and the center point P2 of the second opening 14b are intersections of the long axes of the two long holes forming the respective opening shapes. In the configuration of the first embodiment, all the opening portions of the microwave suction opening 14 are arranged at positions shifted from the center line V (tube axis) in the width direction W of the upper wall surface 9. The major axis direction of each elongated hole in the microwave suction opening 14 is inclined by approximately 45 ° C. with respect to the center line V in the width direction W of the upper wall surface 9.

  As shown in FIG. 11, the first opening 14 a is formed in the vicinity of the concave portion 9 a that is a bonding region in the upper surface wall 9 corresponding to the bonding portion of the coupling portion 7 in the waveguide structure portion 8. The concave portion 9a has a concave shape on the surface (upper surface) in the radial direction of the microwave radiated from the first opening 14a. The two first openings 14a are arranged symmetrically with the center line V in between. The second opening 14 b having an opening shape smaller than the first opening 14 a is formed in the vicinity of the tip opening portion 13 of the upper surface wall 9. The two second openings 14b are arranged symmetrically with the center line V in between.

  As described above, the opening shape of the first opening 14a is a substantially X-shaped shape in which long holes (slits or slots) are intersected so as to be orthogonal to each other. It is not the center position of the length in the major axis direction. That is, the opening shape extending from the center point P1 toward the center line V in the width direction W of the upper wall surface 9 in each elongated hole is formed shorter than the opening shape extending from the center point P1 to the side wall surface.

  As shown in FIG. 3 described above, the coupling portion 7 is provided with a flange 7 b for joining to the upper wall surface 9 of the waveguide structure portion 8. The flange 7b has a flange shape in which the length in the direction (transmission direction) of the tube axis (V) extending in the transmission direction in the waveguide structure 8 is short and the length in the width direction W is long. That is, the coupling portion 7 is formed so that the length in the transmission direction in the waveguide structure is shorter than the length in the direction orthogonal to the transmission direction. For this reason, it becomes possible to form the opening-shaped front-end | tip extended in the direction of the coupling | bond part 7 in the 1st opening 14a close to the coupling | bond part 7. As shown in FIG.

  In the waveguide structure portion 8 in the first embodiment, the flange 7b of the coupling portion 7 is joined to the back surface side of the recess 9a formed in the upper wall surface 9. For this reason, the depth of the concave portion 9a is deeper than the height of the protrusion generated when the flange 7b is joined to the concave portion 9a of the upper wall surface 9, for example, the protrusion of the TOX caulking, the welding mark, the head of the fixing screw or nut, etc. Designed to be By setting the depth of the recess 9a in this way, it is possible to avoid problems such as contact of the protrusion with the back surface of the mounting table 6 disposed above.

  Furthermore, since a concave portion 9a (corresponding to the central region of the heating chamber 2a) is formed in the portion directly above the coupling portion 7 on the upper wall surface 9 of the waveguide structure portion 8 in the first embodiment, (b) in FIG. It becomes a structure which can further suppress the fall of the heating temperature in the center area | region of the heating chamber 2a.

  Hereinafter, a specific opening shape of the first opening 14a in the first embodiment will be described with reference to FIG. In order to facilitate the description, in FIG. 11, the opening shape of the first opening 14 a illustrated on the upper side in the first opening 14 a disposed vertically above and below the center line V will be described.

  First, in the first opening 14a, the first length of the opening extending from the center point P1 toward the inner side (center line V side) in the width direction W in the direction of the recess 9a of the top wall 9 is A (the center point in FIG. 11). The length of the opening extending from P1 to the lower right side and the second length of the opening extending from the center point P1 toward the inside of the width direction W in the direction of the tip opening portion 13 is B (lower left from the center point P1 in FIG. 11). The third length of the opening extending from the center point P1 toward the outside in the width direction W toward the tip open portion side of the upper surface wall 9 is C (in FIG. 11, from the center point P1 to the upper left side). The length of the opening extending from the center point P1 to the outside in the width direction W and extending to the rear side of the upper surface wall 9 is D (the length of the opening extending from the center point P1 to the upper right side in FIG. 11). Sa)).

  As shown in FIG. 11, the third length C and the fourth length D have the same length. The first length A is shorter than the second length B, and the second length B is shorter than the third length C and the fourth length D. That is, the first length A is formed to be the shortest, and the front end portion of the opening having the first length A is located close to the concave portion 9a of the upper surface wall 9 to which the coupling portion 7 is joined. Therefore, the distance X between the front end portion of the opening having the first length A and the center line V in the width direction W of the upper wall surface 9 is equal to the front end portion of the opening having the second length B and the upper wall surface 9. Is longer than the distance Y from the center line V in the width direction W. That is, in the first opening 14a opposed across the center line V, the region between the openings close to the recess 9a (joint portion of the coupling portion 7) of the upper surface wall 9 to which the coupling portion 7 is joined is the recess of the upper surface wall 9. Compared to the region between the openings away from 9a (the coupling portion 7), it is formed in a wide and flat shape.

  In the opening facing the tube axis (center line V) of the waveguide structure, when the region between the openings is not flat but has a shape with irregularities, the electromagnetic field in the waveguide structure is disturbed, There is a problem that the circularly polarized microwave radiated from the aperture is disturbed. For this reason, it is preferable to secure as many flat regions as possible in the region between the openings facing each other across the tube axis. Thus, by making the area between the openings a flat area, the microwave radiated from the openings becomes a beautiful circularly polarized wave with little disturbance, and the aforementioned suction effect is also enhanced. Therefore, in the first opening 14a opposed across the center line V of the waveguide structure portion 8 shown in FIG. 11, the region between the openings near the joint portion of the coupling portion 7 is formed in a wide and flat shape. Therefore, a preferable circularly polarized wave is radiated from each of the first openings 14a, and the suction effect is enhanced. Even when food is arranged in the central region of the heating chamber, the radiation from the first openings 14a is increased. Is possible.

  As described above, in the waveguide structure portion 8 of the waveguide structure antenna according to the first exemplary embodiment, in the opening shape of the two first openings 14a and 14a facing each other with the tube axis (V) therebetween, the coupling portion The distance (X + X) between the opposing openings close to 7 is formed to be longer than the distance (Y + Y) between the opposing openings far from the coupling axis 7, that is, close to the tip opening portion 13. In the waveguide structure portion 8 according to the first embodiment, in the first opening 14a where two long holes intersect, the length (A) of the opening extending in the direction approaching the coupling portion 7 from the intersecting position intersects. Is formed shorter than the length (B, C, D) of the opening extending in a direction other than the direction approaching the coupling portion 7 from.

  In addition, in the opening shape of the first opening 14a facing each other with the tube axis (center line V) in between, the distance between the facing openings is a microwave transmitted in the space in the waveguide structure portion 8 of the waveguide structure. Is set to 1/8 wavelength or more. According to the inventor's experiment, when the distance between the opposed openings is shorter than 1/8 wavelength of the microwave transmitted through the space of the waveguide structure, interference due to microwave radiation from the opposed openings This resulted in a non-uniform heating distribution. According to the inventor's experiment, when the distance between the opposed openings is a length substantially equal to the shaft diameter (18 mm) of the coupling shaft 7a, a preferable heating distribution result was obtained.

  The second opening 14b has an X shape in which two long holes having the same length are orthogonal to each other at the center, and the long axis of each long hole is the center line V in the transmission direction. Is skewed 45 degrees. In the first embodiment, the lengths of the long axes of the respective long holes constituting the second opening 14b are set to be substantially the same as the third length C and the fourth length D. It is set to approximately ¼ wavelength of the microwave transmitted through the structure portion 8.

  Further, the microwave suction opening 14 of the waveguide structure antenna in the first embodiment has a curved surface structure in order to alleviate the concentration of the electric field and prevent the occurrence of abnormal discharge.

  In the waveguide structure antenna in the microwave oven according to the first embodiment, the coupling portion 7 and the waveguide structure portion 8 are joined by using the flange 7b having a short tube axis direction (transmission direction) and a long width direction. Although described, the present disclosure is not limited to this configuration, and can be changed according to the specifications of the microwave heating device. For example, if the length in the transmission direction in the flange portion of the coupling portion 7 is extremely shortened and the structure is joined (caulking, spot welding) to the waveguide structure portion only by the flange portion in the width direction, the number of joint locations is reduced. It is possible to form the opening shape of the microwave suction opening 14 closer to the coupling portion 7.

  Further, in order to avoid an overlap between the flange portion of the coupling portion 7 and the microwave suction opening 14, it is possible to form an opening avoidance portion (slit) in the flange portion so that the flange portion has a special shape. By joining such a specially-shaped flange portion to the waveguide structure portion, the joining state between the coupling portion 7 and the waveguide structure portion 8 can be strengthened without reducing the joint area of the flange portion. It is possible to reduce the variation of products.

  In addition, the coupling shaft 7a of the coupling portion 7 is not formed in a columnar shape, but its cross section is formed in a D shape, an elliptical shape, an I shape, or a round bar shape, and the shape of the flange portion is changed to change the microwave suction opening 14 It is also possible to form the opening shape closer to the coupling shaft 7a. Further, the coupling shaft 7 a having various cross-sectional shapes may be directly joined to the waveguide structure portion 8. With this configuration, it is possible to provide a configuration in which no flange portion is provided, and a configuration in which a space for forming the microwave suction opening 14 can be further secured.

  The microwave oven that is the microwave heating apparatus according to the first embodiment of the present disclosure configured as described above is configured to be able to locally heat an object to be heated in the heating chamber, and to heat the heating chamber. The distribution can be made uniform. In the microwave oven according to the first embodiment of the present disclosure, particularly in the central region of the heating chamber immediately above the rotation center in the waveguide structure antenna, heating can be performed with high efficiency, and the heating temperature of the central region can be increased. It becomes the structure which can suppress nonuniformity.

In the first embodiment, the description has been given of the case where the microwave suction opening has a substantially X shape in which mainly two elongated holes intersect, and the object to be heated sucks the circularly polarized microwave. The microwave heating device of the present disclosure is not limited to such a case. The shape of the microwave suction opening may be other than a substantially X shape and may be any shape that can generate circularly polarized waves. Further, the long hole (or slit) constituting the microwave suction opening is not limited to a rectangle. For example, it is possible to generate circularly polarized waves even when the corner portion of the opening shape is curved or elliptical. As a basic idea of circularly polarized aperture, it can be inferred that two generally elongated ones that are biased toward one of the tube axes may be combined.
Further, the circularly polarized aperture shape is preferably configured with a curve in order to suppress the concentration of the electric field, and all corner portions are formed in the first aperture 14a and the second aperture 14b in the microwave oven of the first embodiment. Is composed of curves.

  Next, rotation control of the waveguide structure antenna 5 performed using the microwave oven 1 according to the first embodiment will be described.

  The present inventors have intensively studied to perform more appropriate heating control depending on the state of the object to be heated. In particular, a diligent study was conducted on the grill mode control in which the grill pan is disposed above the mounting table 6 and the heated object is heated while the heated dish is placed on the grill pan.

  FIG. 12 shows a state in which the grill pan 20 is disposed above the mounting table 6 and the heated object 21 is mounted on the grill pan 20. As shown in FIG. 12, the grill pan 20 is fixed to the side wall 2d of the heating chamber 2a. Specifically, rails (not shown) extending in the front-rear direction are formed on the left and right side walls 2d of the heating chamber 2a, and the grill pan 20 is disposed on the rails. Thereby, the grill pan 20 is disposed at a position above the bottom surface (mounting table 6) in the heating chamber 2a. In the first embodiment, a plurality of rails are provided in the vertical direction on the left and right side walls 2d of the heating chamber 2a, and the height of the grill pan 20 can be adjusted in a plurality of stages (for example, the upper stage). , Middle, lower).

  With reference to FIGS. 13A-13C, grill pan 20 in the first embodiment will be described. FIG. 13A shows a plan view of the grill pan 20 as viewed from above. FIG. 13B shows a side view of the grill pan 20 as viewed from the side. FIG. 13C shows a 9C-9C cross-sectional view in FIG. 13A. The grill pan 20 has a frame-shaped peripheral portion 20a, a plate 20c formed inside thereof, and a plurality of grooves 20b (not shown in FIG. 13C) having a predetermined depth formed in parallel, and a lower portion of the peripheral portion 20a. And an insulating portion 20d provided on the side. An object to be heated 21 is placed on the plate 20c and placed in the heating chamber 2a. The grill pan 20 is disposed in the heating chamber 2a so as to be in contact with the rail provided on the side wall 2d of the heating chamber 2a at the insulating portion 20d. A microwave absorber 20e (for example, ferrite) is provided on the back surface side (mounting table 6 side) of the plate 20c. The back surface of the plate 20 c constitutes the bottom surface 20 f of the grill pan 20. The peripheral portion 20a and the plate 20c are formed of a material that does not transmit microwaves (for example, iron or aluminum). The insulating portion 20d is formed of an insulating material (for example, PPS resin) so as to insulate the grill pan 20 from the side wall 2d of the heating chamber 2a, and is configured to transmit microwaves.

  In such a configuration, as shown in FIG. 12, when the microwave radiated from the waveguide structure antenna 5 reaches the bottom surface 20f of the grill pan 20 (arrow E), the microwave absorber provided on the bottom surface 20f. The bottom surface 20f of the grill pan 20 is heated by the action of 20e. Thereby, the to-be-heated object 21 on the grill pan 20 is indirectly heated by the microwave. On the other hand, the peripheral portion 20a and the plate 20c of the grill pan 20 in the first embodiment are made of a material that does not allow microwaves to pass through. However, between the grill pan 20 and the side wall 2d of the heating chamber 2a, the microwaves are formed. A gap is also formed through which light can pass. Specifically, in the grill pan 20, an insulating portion 20 d is provided at a location that contacts the rail provided on the side wall 2 d of the heating chamber 2 a, and the PPS resin forming the insulating portion 20 d transmits microwaves. It is a material to make. Therefore, microwaves can be transmitted through the insulating portion 20d from between the grill pan 20 and the left and right side walls 2d of the heating chamber 2a. Moreover, in the front direction of the grill pan 20, the glass constituting the door is a material that transmits microwaves, and the microwaves can be transmitted. Further, in the rearward direction of the grill pan 20, when irregularities or the like are formed on the side wall 2d of the heating chamber 2a, microwaves can be transmitted through the gap. Further, since the corner portion of the grill pan 20 is formed in an arc shape, a gap is generated between the corner portion of the grill pan 20 and the heating chamber 2a so that microwaves can be transmitted. With such a configuration, apart from the microwave absorbed by the bottom surface 20f of the grill pan 20, on the grill pan 20 where the heated object 21 is disposed through the gap between the grill pan 20 and the side wall 2d of the heating chamber 2a. A flow in which microwaves reach the space is generated (arrow F). The heated object 21 is directly heated by such a microwave flow.

  As described above, when heating the object to be heated 21 in the arrangement shown in FIG. 12 (grill mode), a microwave flow for indirectly heating the object to be heated 21 via the bottom surface 20f of the grill pan 20 ( There are two flows: an arrow E), a microwave flow (arrow F) that directly heats the article 21 to be heated through the gap between the grill pan 20 and the side wall 2d of the heating chamber 2a. By combining these two flows, the article to be heated 21 is heated from each direction.

  Next, the present inventors relate the microwave heating performance of the waveguide structure antenna 5 in the grill mode to the relationship with the direction of the waveguide structure antenna 5 in the feed chamber 2b shown in FIGS. 2A and 2B. Considered. This consideration will be described with reference to FIGS. 14A, 14B, 15A, and 15B.

  14A and 14B are a plan view and a perspective view, respectively, showing a first rotation state of the waveguide structure antenna 5 in the grill mode. 15A and 15B are a plan view and a perspective view, respectively, showing a second rotation state of the waveguide structure antenna 5 in the grill mode. 14A and 14B show a state in which the open end portion 13 of the waveguide structure antenna 5 faces the protruding portion 18 of the power supply chamber 2b. 14A and 14B particularly show the waveguide structure antenna 5 facing left. The second rotation state shown in FIGS. 15A and 15B represents a state where the distal end opening portion 13 of the waveguide structure antenna 5 does not face the protruding portion 18 of the power supply chamber 2b. FIGS. 15A and 15B particularly show a state in which the waveguide structure antenna 5 is facing left rear (a state in which the open end portion 13 faces the corner portion 22a of the power supply chamber 2b).

  In the grill mode according to the arrangement of FIGS. 14A, 14B, 15A, and 15B, the object to be heated 21 is not placed on the placing table 6 that is the bottom surface in the heating chamber 2a. Therefore, the microwave suction effect by the first opening 14a and the second opening 14b of the circularly polarized aperture described above cannot be obtained so much. Therefore, more microwaves from the waveguide structure antenna 5 tend to be radiated from the open end portion 13 than from the first opening 14a and the second opening 14b.

  In the first rotation state shown in FIGS. 14A and 14B, the tip opening portion 13 faces the protruding portion 18a of the power supply chamber 2b. Therefore, the microwave radiated | emitted from the front-end | tip open part 13 is reflected upward by the protrusion part 18a (arrow H). Since the protruding portion 18a is a portion protruding inward of the power supply chamber 2b, the microwave reflected by the protruding portion 18a rises in the left and right direction and the center side region in the front-rear direction in the power supply chamber 2b. Become. The microwave rising in this way reaches the bottom surface 20f of the grill pan 20 disposed in the heating chamber 2a. Similarly, the microwaves (arrow I) radiated upward from the first opening 14a and the second opening 14b reach the bottom surface 20f of the grill pan 20. Thus, most of the microwaves radiated from the waveguide structure antenna 5 reach the bottom surface 20 f of the grill pan 20. Thereby, the indirect heating via the bottom face 20f of the grill pan 20 is promoted. That is, in the first rotation state, microwave radiation is performed in a state in which the tip open portion 13 faces the protruding portion 18 of the power supply chamber 2b, thereby passing through the gap between the grill pan 20 and the side wall 2d of the heating chamber 2a. Rather than direct microwave heating (corresponding to the arrow F in FIG. 12), indirect microwave heating via the bottom surface 20f of the grill pan 20 (the microwave absorber becomes hot and lowers the object to be heated). To bake with heat, corresponding to arrow E in FIG. 12).

  Note that “the tip open portion 13 faces the protruding portion 18” means that the direction in which the tip open portion 13 faces (matches the microwave transmission direction Z) overlaps at least a part of the protruded portion 18. To do.

  On the other hand, in the second rotation state shown in FIGS. 15A and 15B, the tip opening portion 13 is a corner of the power supply chamber 2b that is a region other than the protruding portion 18 of the power supply chamber 2b (the corner portion in the example of FIGS. 15A and 15B). 22a). Thereby, the microwave radiated | emitted from the front-end | tip opening part 13 is reflected upwards at the corner | angular part 22a of the electric power feeding chamber 2b (arrow K). The reflected microwave rises in the vicinity of the corner 22a in the power supply chamber 2b, and similarly rises in the corner in the heating chamber 2a. The microwave that has risen in this way reaches a gap (in particular, a gap at the corner) between the grill pan 20 and the side wall 2d of the heating chamber 2a. The microwaves that have reached the gap enter the space above the grill pan 20 in which the object to be heated 21 is disposed, and directly heat the object to be heated 21. On the other hand, a small amount of microwaves (arrow L) radiated upward from the first opening 14a and the second opening 14b reach the bottom surface 20f of the grill pan 20 disposed in the heating chamber 2a, and the grill pan 20 Indirect heating is performed via the bottom surface 20f. Thus, most of the microwaves radiated from the waveguide structure antenna 5 reach the gap between the grill plate 20 and the side wall 2d of the heating chamber 2a rather than the bottom surface 20f of the grill plate 20. Direct heating by microwave is promoted. That is, in the second rotation state, microwave radiation is performed in a state where the tip opening portion 13 does not face the protruding portion 18 of the power supply chamber 2b, thereby making it more than indirect heating via the bottom surface 20f of the grill pan 20. Direct microwave heating through the gap between the grill pan 20 and the side wall 2d of the heating chamber 2a can be focused.

  15A and 15B, the case where the tip opening portion 13 faces the corner (corner portion 22a) of the power supply chamber 2b has been described. However, not only the corner of the power supply chamber 2b but also, for example, the front direction of the power supply chamber 2b and Even in the case of facing backward, the microwave radiated from the open end portion 13 is similarly reflected upward by the side wall 2c of the power supply chamber 2b. As a result, the reflected microwave rises in the corner regions of the power supply chamber 2b and the heating chamber 2a and reaches the gap between the grill pan 20 and the side wall 2d of the heating chamber 2a. The microwaves that have reached the gap then wrap around the space above the grill pan 20 and heat the object to be heated 21 directly. Including such a case, if the tip opening portion 13 does not face the protruding portion 18 of the power supply chamber 2b, a lot of microwaves can be circulated into the space above the grill pan 20.

  Based on the above-mentioned consideration, the present inventors control the first open portion 13 of the waveguide structure antenna 5 toward the projecting portion 18 of the power supply chamber 2b (first rotation state), and the projecting portion 18 of the power supply chamber 2b. It has been found that the heating form of the article to be heated 21 can be varied by properly using the control that is not directed (second rotation state). The control flow invented by the present inventors based on this knowledge will be described with reference to FIGS. In the control flow, in the grill mode in which the object to be heated 21 is placed on the grill pan 20 and heated by the grill, control according to the state of the object to be heated 21, particularly whether the object to be heated 21 is frozen food or not. It is devised to perform more appropriate control according to the situation.

(First grill mode)
FIG. 16 is a diagram illustrating a control flow corresponding to the first grill mode by the control unit 17. The first grill mode is a mode in which indirect heating via the bottom surface 20f of the grill pan 20 is focused on the object 21 to be heated. The flow is heating control that is particularly effective when the article to be heated 21 is a food other than frozen food. 17 (a) -17 (e) are diagrams showing the rotational position of the waveguide structure antenna 5 corresponding to each step of the control flow shown in FIG.

  As shown in FIG. 16, when the mode is started, first, rotational movement is performed (step S1). Specifically, as shown in FIG. 17A, the motor 15 that is a rotation driving unit rotates the coupling portion 7 of the waveguide structure antenna 5, so that the waveguide structure antenna 5 is coupled to the coupling portion 7. It rotates around the rotation center G of the coupling shaft 7a. In the first embodiment, the waveguide structure antenna 5 is controlled to rotate at a constant speed in a clockwise direction when viewed from above (for example, a speed of 10.2 seconds / 1 rotation). In Step S1, the waveguide structure antenna 5 starts from a state in which the distal end opening portion 13 of the waveguide structure antenna 5 faces rearward in the feeding chamber 2b. Hereinafter, with respect to the direction of the waveguide structure antenna 5 (open end portion 13), the rear is set to 0 °, and the angle of 0 ° to 360 ° is set clockwise with respect to the rear.

  Next, a right stop is performed (step S2). Specifically, as shown in FIG. 17B, control is performed such that the waveguide structure antenna 5 is stopped when it substantially faces rightward. More specifically, the waveguide structure antenna 5 is stopped in a state where the open end 13 of the waveguide structure antenna 5 faces the right protrusion 18b in the power supply chamber 2b (for example, orientation of 95 °).

  Then, after stopping for a predetermined time (for example, 4.9 seconds), the rotational movement is performed again (step S3). Specifically, the waveguide structure antenna 5 stopped rightward is controlled to rotate clockwise at a constant speed as shown in FIG. 17C (for example, the same as step S1). 10.2 seconds / revolution speed).

  Next, a leftward stop is performed (step S4). Specifically, as shown in FIG. 17 (d), control is performed so that the waveguide structure antenna 5 is stopped when it is substantially directed leftward. More specifically, the waveguide structure antenna 5 is stopped in a state where it faces the left protrusion 18a in the feeding chamber 2b (for example, orientation of 275 °). In the first embodiment, the stop is performed for the same time (for example, 4.9 seconds) as the predetermined time in step S2.

  When the stop in step S4 is completed, finally, rotational movement is performed (step S5). Specifically, the waveguide structure antenna 5 stopped leftward is controlled to rotate at a constant speed clockwise as shown in FIG. 17E (for example, steps S1 and S3). The same speed as 10.2 sec / rotation).

  By repeating steps S1-S5, as shown in FIGS. 17 (a) -17 (e), while the waveguide structure antenna 5 is rotated in the same direction at a constant speed, the projecting portions 18a, 18b of the feeding chamber 2b are rotated. It can be controlled to stop when it faces. Thereby, when rotating the waveguide structure antenna 5, it is possible to lengthen the time during which the open end portion 13 of the waveguide structure antenna 5 faces the projecting portions 18a and 18b of the feeding chamber 2b. By such control, the object to be heated 21 is heated while rotating radially about the rotation center G of the coupling shaft 7a, and indirect heating via the bottom surface 20f of the grill pan 20 is focused. Yes (see description of FIGS. 14A and 14B). Such heating mainly enables the food to be efficiently and more uniformly heated (ie, baked) when grilling the normal food other than the frozen food. In response to this, the control unit 17 in the first embodiment performs control including at least the first grill mode when the grill mode in which food other than the frozen food is the heated object 21 is selected. I have to. Thereby, more appropriate heating control can be performed according to the state of food (normal temperature or refrigerated state). In other words, you can bake quickly and deliciously.

(Second grill mode)
FIG. 18 is a diagram illustrating a control flow corresponding to the second grill mode by the control unit 17. The second grill mode is a mode in which direct heating is performed on the article to be heated 21 through the gap between the grill pan 20 and the side wall 2d of the heating chamber 2a. This flow is particularly heating control that is effective when the article to be heated 21 is frozen food. 19 (a) -19 (e) are diagrams showing the rotational position of the waveguide structure antenna 5 corresponding to each step of the control flow shown in FIG.

  As shown in FIG. 18, when the mode is started, first, rotational movement is performed (step S6). Specifically, as shown in FIG. 19A, when the motor 15 which is a rotation driving unit rotates the coupling portion 7 of the waveguide structure antenna 5, the waveguide structure antenna 5 is coupled to the coupling portion 7. It rotates around the rotation center G of the coupling shaft 7a. In the first embodiment, the waveguide structure antenna 5 is controlled to rotate at a constant speed in a clockwise direction when viewed from above (for example, a speed of 6.12 seconds / 1 rotation). Also in step S6, similarly to step S1 described above, it starts from a state in which the open end 13 of the waveguide structure antenna 5 faces rearward in the feeding chamber 2b.

  Next, a right rearward stop is performed (step S7). Specifically, as shown in FIG. 19B, control is performed so that the waveguide structure antenna 5 is stopped when the waveguide structure antenna 5 is substantially directed rearward to the right. More specifically, the waveguide structure antenna 5 is stopped in a state in which the open end portion 13 of the waveguide structure antenna 5 faces the area near the corner portion 22b of the power supply chamber 2b (for example, the direction of 65 °).

  Then, after stopping for a predetermined time (for example, 3.92 seconds), the rotational movement is performed again (step S8). Specifically, as shown in FIG. 19C, control is performed so that the waveguide structure antenna 5 stopped at the right rear side is rotated clockwise at a constant speed (for example, step S6 and step S6). (Same speed of 6.12 seconds / revolution).

  Next, a left rearward stop is performed (step S9). Specifically, as shown in FIG. 19 (d), control is performed so that the waveguide structure antenna 5 is stopped when the waveguide structure antenna 5 is substantially left rearward. More specifically, the waveguide structure antenna 5 is stopped in a state where the open end portion 13 of the waveguide structure antenna 5 faces the vicinity of the corner portion 22a of the power supply chamber 2b (for example, orientation of 305 °). In the first embodiment, the stop is performed for the same time as the predetermined time in step S7 (eg, 3.92 seconds).

  When the stop in step S9 is completed, finally, rotational movement is performed (step S10). Specifically, as shown in FIG. 19E, the waveguide structure antenna 5 stopped in the rear left direction is controlled to rotate clockwise at a constant speed (for example, steps S6 and S8). The same speed as 6.12 seconds / revolution).

  By repeating steps S6 to S10, as shown in FIGS. 19 (a) to 19 (e), while the waveguide structure antenna 5 is rotated in the same direction at a constant speed, the projecting portions 18a and 18b of the feeding chamber 2b are rotated. Can be controlled to stop in a state in which it does not face (in the first embodiment, a state in which the power supply chamber 2b faces the corners 22a and 22b). Thereby, when rotating the waveguide structure antenna 5, it is possible to lengthen the time during which the open end 13 of the waveguide structure antenna 5 does not face the protruding portion 18 of the feeding chamber 2b. By such control, the microwave is radiated while rotating radially around the rotation center G of the coupling shaft 7a, and direct heating through the gap between the grill pan 20 and the side wall 2d of the heating chamber 2a is emphasized. (See description of FIGS. 15A and 15B). Such heating is mainly effective when grilling frozen food. In general, it is known that when frozen food is baked only with heat from a heater or a grill pan, the surface is burnt and the inside is kept cold. It is better to thaw frozen foods first and then bake. Direct microwave heating is effective for thawing (can reach the inside of the food and dissolve it). Therefore, by focusing on direct microwave heating through the gap between the grill pan 20 and the side wall 2d of the heating chamber 2a, the frozen food can be thawed efficiently and more uniformly without scorching. In response to this, the control unit 17 in the first embodiment performs control including at least the second grill mode when the grill mode in which the frozen food is to be heated 21 is selected. . Thereby, more suitable heating control can be performed according to the state (frozen state) of food.

  As described above, the control unit 17 of the microwave oven 1 according to the first embodiment can selectively use the first grill mode or the second grill mode according to the state of the article to be heated 21. Appropriate control can be performed.

  In the first embodiment, in the first and second grill modes, the time for stopping the waveguide structure antenna 5 is provided, so that the time when the tip open portion 13 faces the projecting portion 18 and the time when it does not go are respectively set. Although it was made long, it is not restricted to such a case. For example, by setting the rotation speed of the waveguide structure antenna 5 variably in accordance with the direction in which the distal end opening portion 13 faces without providing the stop time of the waveguide structure antenna 5, each time is lengthened. It may be. Specifically, as in the first grill mode described with reference to FIGS. 16 and 17, the indirect heating of the object to be heated 21 through the bottom surface 20 f of the grill pan 20 is emphasized. The same can be achieved by controlling the rotational speed of the waveguide structure antenna 5 as shown in FIG. In the example shown in FIG. 20, relative to the case where the distal end opening portion 13 of the waveguide structure antenna 5 is directed rightward and leftward, and before and after that, the rotational speed of the waveguide structure antenna 5 is relative to the other direction. Try to be late. Even in such a setting, it is possible to lengthen the time during which the open end portion 13 of the waveguide structure antenna 5 faces the protruding portion 18 of the power supply chamber 2b. It can be carried out. Similarly, the direct heating of the heated object 21 through the gap between the grill pan 20 and the heating chamber 2a as in the second grill mode described with reference to FIGS. The same can be achieved by controlling the rotational speed of the waveguide structure antenna 5 as shown in FIG. In the example shown in FIG. 21, the case where the distal end opening portion 13 of the waveguide structure antenna 5 is directed to the right rear and the left rear direction, and before and after that, the rotation speed of the waveguide structure antenna 5 is set to other directions. Also try to be relatively slow. Even in such a setting, it is possible to lengthen the time during which the open end portion 13 of the waveguide structure antenna 5 does not face the protruding portion 18 of the power supply chamber 2b, and particularly heating suitable for frozen foods can be performed. it can.

  In the first embodiment, the case where the waveguide structure antenna 5 is stopped for the same time in the right direction and the left direction in the first grill mode has been described. However, the present invention is not limited to such a case. For example, it may be stopped for different times in the right direction and the left direction. Alternatively, it may be stopped either in the right direction or the left direction. Similarly, in the second grill mode, the case where the waveguide antenna 5 is stopped for the same time in the right rear direction and the left rear direction has been described. However, the present invention is not limited to this case. For example, it may be stopped for different times depending on the right rear direction and the left rear direction. Alternatively, it may be stopped either in the right rear direction or in the rear direction. Furthermore, it may be stopped in the right front direction or the left front direction without stopping in the right rear direction and the left rear direction.

  In the first embodiment, the waveguide structure antenna 5 is rotated in the same direction at a constant speed in the first and second grill modes. However, the present invention is not limited to such a case. Absent. For example, the rotation direction of the waveguide structure antenna 5 may be reversed during the rotation.

  In the first embodiment, the case where the first and second grill modes are performed independently has been described. However, the present invention is not limited to such a case. For example, the first and second grill modes may be combined with each other, or the first and second modes may be combined with other modes (for example, the waveguide structure antenna 5 is always in the same direction). Mode that rotates at a constant speed). In other words, by performing heating control including at least the first grill mode, efficient heating suitable for foods other than frozen foods can be performed. Similarly, by performing heating control including at least the second grill mode, efficient heating suitable for frozen food can be performed. Efficient heating suitable for frozen foods can be performed. As an example, you may want to bake frozen food. At this time, the frozen food can be thawed by setting the first half as the second grill mode, and then the first grill mode can be switched to the second half to burn the surface and burnt. As a result, it is possible to bake the inside properly and bake the surface appropriately. It is effective to use a sensor for switching the grill mode. For example, the temperature of the food may be detected by a temperature sensor while heating in the second grill mode, and the temperature may be switched to the first grill mode when it reaches a temperature at which it can be determined that thawing has ended (for example, 0 degrees). As a matter of course, the sensor is not limited to the temperature sensor, and may be determined by an appearance using a CMOS camera or the like, or the generation of vapor from food may be detected by a humidity sensor. There is a possibility that it can be realized even by a method of detecting a smell or a change in weight.

  In the first embodiment, the case where the control unit 17 includes both the first and second grill modes has been described. However, the present invention is not limited to such a case, and at least the first grill mode is provided. Good. By having at least the first grill mode, more appropriate control can be performed according to the state of the object to be heated 21.

  Moreover, although Embodiment 1 demonstrated the case where protrusion part 18a, 18b was provided so that the side wall 2c on either side might be formed, it is not restricted to such a case. For example, the arrangement position of the protruding portion 18 may be appropriately determined according to the cross-sectional shape of the power supply chamber 2b in plan view. Further, the protruding portion 18 is not limited to the one that forms the side wall 2c, and may be provided independently of the side wall 2c without forming the side wall 2c on the center side of the bottom wall 11. In other words, the protruding portion 18 only needs to protrude from the “bottom wall 11” of the power supply chamber 2b toward the power supply chamber 2b.

  As described above, in the microwave heating device of the present disclosure, more appropriate heating control can be performed according to the state of the object to be heated. For this reason, this indication can be effectively used also when using as a microwave heating device which performs heating processing, sterilization processing, etc. to a thing to be heated.

  While the present disclosure has been fully described in connection with preferred embodiments with reference to the accompanying drawings, various variations and modifications will be apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present disclosure as set forth in the appended claims.

  The present disclosure relates to a cooking device that performs dielectric heating by radiating microwaves to food as an object to be heated, particularly a cooking device used in combination with other heating such as an oven, a grill, and superheated steam, as well as a drying device, ceramics It is useful in microwave heating devices in various industrial applications such as industrial heating devices, garbage disposal machines, and semiconductor manufacturing devices.

DESCRIPTION OF SYMBOLS 1 Microwave oven 2 Heating part 2a Heating chamber 2b Feeding room 2c Side wall 2d Side wall 3 Magnetron (microwave generation part)
4 Waveguide (Transmission part)
DESCRIPTION OF SYMBOLS 5 Waveguide structure antenna 6 Mounting base 7 Coupling part 8 Waveguide structure part 9 Upper wall surface 11 Bottom wall 12 Low impedance part 13 Open end part 14 Microwave suction opening 14a 1st opening 14b 2nd opening 15 Motor (rotation drive part) )
16 Infrared sensor (status detector)
17 Control part 18 (18a, 18b) Projection part 20 Grill pan 20a Peripheral part 20b Groove 20c Plate 20d Insulation part 20e Microwave absorber 20f Bottom surface 21 Heated object 22a, 22b, 22c, 22d Corner part

Claims (13)

A heating chamber that forms a space above the mounting table for mounting the object to be heated, and a power supply chamber that forms a space below the mounting table, and stores the object to be heated in the heating chamber. A heating unit to
A microwave generator for generating microwaves;
A transmission unit for transmitting the microwave generated by the microwave generation unit;
A waveguide structure having a space for transmitting microwaves, and a waveguide structure antenna disposed in the feeding chamber so as to radiate microwaves of the transmission unit to the heating unit;
A rotation driving unit for rotating the waveguide structure antenna;
A control unit for controlling the driving of the rotation drive unit,
The waveguide structure antenna guides the microwave of the transmission unit to the space of the waveguide structure, and is coupled to the coupling unit that can be rotated by the rotation driving unit and to the coupling unit. A waveguide structure that defines a space;
The waveguide structure includes an open end portion that radiates a microwave transmitted from the coupling portion through the space of the waveguide structure toward a sidewall of the power supply chamber, and a microwave in the space of the waveguide structure. A microwave suction opening that is circularly polarized and radiates toward the heating chamber,
On the bottom wall of the power supply chamber, a protruding portion that protrudes toward the power supply chamber is formed,
The control unit has a grill mode in which the object to be heated is placed on a grill pan arranged above the mounting table and heated.
The microwave heating apparatus, wherein the grill mode includes a first grill mode in which a time for the open end portion to face the protruding portion of the power supply chamber is increased.   In the first grill mode, the control unit stops when the rotation driving unit rotates the waveguide structure antenna in a state where the open end portion faces the protruding portion of the power supply chamber. The microwave heating apparatus according to claim 1, wherein the microwave heating apparatus is controlled to include time.   In the first grill mode, the control unit rotates at a rotation speed when the distal end opening portion faces the protruding portion of the feeding chamber when the rotation driving unit rotates the waveguide structure antenna. The microwave heating device according to claim 1 or 2, wherein the temperature is controlled so as to be relatively slower than a rotation speed when not facing the protruding portion of the power supply chamber.   4. The control unit according to claim 1, wherein the control unit performs control including at least the first grill mode when a grill mode in which food other than frozen food is used as the object to be heated is selected. The microwave heating apparatus as described in one.   The microwave heating apparatus according to any one of claims 1 to 4, wherein the grill mode includes a second grill mode in which a time during which the tip opening portion does not face the protruding portion of the power supply chamber is lengthened. .   In the second grill mode, the control unit stops when the rotation driving unit rotates the waveguide structure antenna in a state where the open end portion does not face the protruding portion of the power supply chamber. The microwave heating device according to claim 5, wherein the microwave heating device is controlled to include time.   In the second grill mode, the control unit has a rotation speed when the tip opening part does not face the protruding part of the feeding chamber when the rotation driving unit rotates the waveguide structure antenna. The microwave heating device according to claim 5 or 6, wherein the microwave heating device is controlled so as to be relatively slower than a rotation speed when facing the protruding portion of the power supply chamber.   8. The control unit according to claim 5, wherein the control unit performs control including at least the second grill mode when a grill mode in which frozen food is the heated object is selected. Microwave heating device.   The microwave heating apparatus according to any one of claims 1 to 8, wherein the side wall of the power supply chamber is inclined so as to spread outward toward the heating chamber.   The microwave heating apparatus according to claim 9, wherein the power supply chamber has a substantially rectangular cross section in plan view and has the protruding portion on a bottom wall on a short side of the rectangle.   The coupling unit is connected to the rotation driving unit and rotates, and has a coupling axis having a rotation axis that intersects a transmission direction in the waveguide structure, and the rotation center of the coupling axis includes the heating chamber and the rotation axis. The microwave heating device according to any one of claims 1 to 10, wherein the microwave heating device is located at a center in a front-rear direction and a left-right direction in the power supply chamber.   The microwave suction opening has a shape including an opening where at least two long holes intersect, and is formed at a position offset to one side with respect to a tube axis extending in a transmission direction in the waveguide structure. The microwave heating device according to any one of 1 to 10.   The waveguide structure section includes a plurality of the microwave suction openings, and the plurality of microwave suction openings are arranged symmetrically with respect to a tube axis extending in a transmission direction of the waveguide structure. The microwave heating device according to any one of 1 to 12.

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