JP4888221B2 - Microwave heating device - Google Patents

Description

  The present invention relates to a microwave heating apparatus that heats an object to be heated with microwaves.

  A microwave oven, which is a typical microwave heating device, can directly heat food that is a typical object to be heated, so there is no need to prepare a pot or kettle, and it is essential for living. It has become a cooking utensil. In the conventional microwave ovens, the size of the space for storing the food in the heating chamber where microwaves are radiated is generally 300 to 400 mm in the width direction and the depth direction, and approximately 200 mm in the height direction. Yes.

  In recent years, a highly convenient product has been put into practical use in which the bottom of the space for storing food is flattened, the width dimension is set to 400 mm or more, which is relatively larger than the depth dimension, and a plurality of foods can be arranged and heated simultaneously. Has been.

  By the way, the wavelength of the microwave used in the microwave oven is about 120 mm, a strong and weak electric field distribution is generated in the heating chamber, and furthermore, the influence of the shape of the object to be heated and its physical characteristics is synergistically generated to cause uneven heating. It is known. Although it is desirable that the unevenness of heating be as small as possible, particularly in the case of a heating chamber having a large size in the width direction, it is necessary to further increase the uniformity of heating in order to heat foods contained in a plurality of dishes at the same time.

  Conventionally, this type of microwave heating apparatus has been provided with a single radiating antenna and rotationally drives the antenna. However, in recent years, as a measure for improving the uniformity of heating, or with a plurality of radiating antennas, The thing provided with the following high frequency stirring means is proposed (for example, refer patent document 1).

  However, even if the inside of the heating chamber is large, it is not always possible to heat a large amount of food at the same time.For example, when heating a full mug of milk, even if the entire inside of the heating chamber is not heated uniformly, it is only milk. It is more efficient to concentrate and heat.

  Also, even when heating multiple foods at the same time, if there is a difference in the temperature before the food is warmed, for example, when heating frozen food and food at room temperature at the same time, only low temperature food is concentrated. You may want to heat. Furthermore, if you want to heat only the food to be heated intensively when one food contains food that is not heated, such as pickles, salads, and desserts, and food that is heated, such as rice and side dishes, as in a box lunch box There is.

In such a case, a function capable of centrally heating only the local area is required instead of heating the entire inside of the heating chamber uniformly. As what implement | achieves this, what has enabled the concentrated heating by switching a some rotating antenna and controlling a stop position is proposed (for example, refer patent document 2).
JP 2004-259646 A Japanese Patent No. 3617224

In the above-described conventional configuration, for localized heating, for example, like the microwave oven shown in FIG. 9, two rotary antennas 19 and 19 having the same shape are arranged symmetrically with respect to the center of the heating chamber 20. It is said that central heating can be realized by stopping the end portions 21 and 21 having strong directivities of the antennas 19 and 19 in a direction in which local heating is desired. For example, in the directions shown in FIGS. 9A and 9B, the center of the food placed in the middle of the heating chamber can be intensively heated. However, as the antenna directivity increases, the electric field tends to concentrate on the tip of the antenna, and in the antenna driven to rotate as shown in FIG. 9, the locus of the antenna becomes a circle. It will be strongly heated and it may happen that food placed in that area will locally overcook. In particular, in the case of a plurality of antennas as shown in FIG. 9, it is conceivable that the antennas are stopped at positions where the antennas face each other in order to heat the center. The microwave heating chamber is a cavity resonator in which microwaves are confined, and standing waves are also generated. Therefore, a place where the standing wave is strong and the tip of the antenna also passes is most likely to be overcooked.

  The present invention has been made in view of the above-described conventional circumstances, and an object of the present invention is to prevent overcooking in the vicinity of an antenna passing region between a plurality of antennas in a microwave heating apparatus that controls a heating distribution according to directions of the plurality of antennas. And

  A microwave heating apparatus according to the present invention includes a microwave generation unit that generates a microwave, a waveguide that propagates the microwave from the microwave generation unit, and a heating chamber that houses an object to be heated by the microwave. A plurality of rotating antennas that radiate the microwave from the waveguide to the heating chamber, a driving unit that drives the rotating antenna, and a control unit that controls the driving unit to control the direction of the rotating antenna And a matching plate made of a conductive material integrated on the wall surface of the heating chamber between the plurality of rotating antennas.

  With this configuration, since the matching plate is arranged between the plurality of antennas, it is possible to reflect at least a part of the microwave when the antennas face each other, and as a result, the electric field concentration near the antenna tip is dispersed, and the local food Overcooking can be prevented.

  In addition, as an aspect of the present invention, the above microwave heating apparatus includes a configuration in which the matching plate is arranged in a tangential direction with respect to the outer periphery of the rotating antenna.

  With this configuration, the matching plate faces the rotating antenna, so that the microwave radiated from the rotating antenna can be effectively reflected, the electric field concentration near the tip of the antenna is dispersed, and the food is localized. Overcooking can be prevented.

  In addition, as an aspect of the present invention, the above microwave heating apparatus includes a configuration in which the matching plate has a tip portion facing the rotating antenna.

  With this configuration, the effect of the alignment plate can be further enhanced.

  Furthermore, as one aspect of the present invention, the microwave heating apparatus described above includes a configuration in which the control unit controls the rotating antenna so that the direction with strong directivity is stopped toward the alignment plate.

  With this configuration, the effect of the alignment plate can be enhanced most.

  According to the present invention, since the matching plate is arranged between the plurality of antennas, it is possible to reflect at least a part of the microwave when the antennas face each other, and as a result, the electric field concentration near the antenna tip is dispersed, and the food It is possible to prevent local overcooking.

  A microwave heating apparatus according to a first aspect of the present invention stores a microwave generator that generates a microwave, a waveguide that propagates the microwave from the microwave generator, and an object to be heated by the microwave. A heating chamber, a plurality of rotating antennas that radiate the microwaves from the waveguide to the heating chamber, a driving unit that drives the rotating antenna, and a direction of the rotating antenna by controlling the driving unit Since the control unit and the plurality of rotating antennas have a matching plate made of a conductive material integrated on the wall surface of the heating chamber, the matching plate is arranged between the plurality of antennas. Can reflect at least part of the microwaves when facing each other, and as a result, it can disperse the electric field concentration near the tip of the antenna and prevent local overcooking of food Kill.

  The microwave heating apparatus according to the second aspect of the present invention includes a configuration in which the matching plate is arranged in a tangential direction with respect to the outer periphery of the rotating antenna. With this configuration, the matching plate faces the rotating antenna. The microwave radiated from the rotating antenna can be reflected effectively, and the electric field concentration near the tip of the antenna can be dispersed to prevent local overcooking of food.

  The microwave heating device according to the third aspect of the invention includes a configuration in which the matching plate has a configuration having a tip portion facing the rotating antenna, and this configuration can further enhance the effect of the matching plate.

  The microwave heating apparatus according to the fourth aspect of the invention includes a configuration in which the control unit controls the rotation antenna to stop the direction having strong directivity toward the alignment plate. The effect can be enhanced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by this embodiment.

(Embodiment 1)
1 and 2 are diagrams showing a schematic configuration of a microwave oven that is a microwave heating apparatus according to an embodiment of the present invention. FIG. 1 is a plan sectional view seen from above, and FIG. 2 is a front view seen from the front. It is sectional drawing.

  In FIG. 1, the microwave oven of the present embodiment is connected to a magnetron 1 that is a typical microwave generator, a waveguide 2 that propagates microwaves emitted from the magnetron 1, and an upper portion of the waveguide 2. The heating chamber 3, the mounting table 5 on which the food 4 that is a typical object to be heated is mounted, the antenna space 6 formed below the mounting table 5, and the heating chamber 3 are fitted with two coupling holes 7 and 7 provided on the bottom surface at an approximately equal distance from the center of 3 and rotating antennas 8 and 8 disposed in the antenna space 6 and rotatable about the coupling holes 7 and 7. The motors 9 and 9 function as drive units that drive the rotating antennas 8 and 8 via the drive shaft, and the control unit 10 that controls the rotation and stop of the motors 9 and 9.

  Moreover, the microwave oven of this embodiment is provided with the setting means 11, and a user can select a cooking menu according to food or cooking content. Based on the selection result, the control unit 10 controls the magnetron 1 to generate and stop the microwave, and also controls the motor 9 to control the rotation and stop of the rotating antennas 8 and 8. Thereby, the food 4 mounted on the mounting table 5 can be heated and cooked.

  The rotating antenna 8 is a substantially L-shaped patch antenna. The rotating antenna 8 penetrates the coupling portion 7 through the radiation portion 81 made of a flat conductive material having a longitudinal direction along the L shape, and is electrically connected to the radiation portion 81. And a coupling portion 82 made of a cylindrical conductive material integrated mechanically.

  FIG. 3 is a plan view illustrating a specific shape of the radiating portion 81.

  In FIG. 3, the length from the center of the coupling portion 82 of the radiating portion 81 to the end portion 84 in the longitudinal direction of the long side 81a along the L-shape is 50 mm. On the other hand, along an alternate long and short dash line (hereinafter referred to as a reference line) having a long side width of 30 mm, it bends in an L shape at an angle of 83.62 ° at a position of 35 mm from the center of the coupling portion 82, and from there The creeping surface of the end portion 83 of the short side 81b along the L-shape of the radiating portion 81 at a distance of 45 mm is configured to form a part of an arc having a radius of 60 mm with the coupling portion 82 as the center.

  When the overall shape of the radiating portion 81 in plan view is grasped as an L shape, the long side 81a is defined as a first portion coupled to the coupling portion 82, while the short side 81b is defined as the first portion. Defined as the intersected second part. In addition, as described above, the length in the longitudinal direction of each part (the first part and the second part) of the radiating part is the length of the reference line indicated by the alternate long and short dash line located at the center in the width direction of the radiating part. It can be defined by the length of the direction.

  According to this shape, the rotation diameter of the radiating portion 81 centered on the coupling portion 82 is 120 mm, which corresponds to the wavelength of the microwave (one wavelength), and the diameter when the antenna rotates from the width of the heating chamber 4. Is a dimension that can be used even when is limited to one wavelength or less of the microwave.

  In other words, in the present embodiment, the radiating portion 81 has two portions that intersect each other, ie, the first portion (long side 81a) and the second portion (short side 81b), and thus is restricted by the rotation diameter. Even in a narrow space, a substantially larger length (a length along the reference line) than the simple rotation diameter or rotation radius is secured. Specifically, in FIG. 3, the radius of rotation is 60 mm, but the substantial length of the radiating portion corresponding to the radius is 35 + 45 mm = 80 mm. Therefore, it is considered that microwaves with strong directivity can be emitted even in a narrow space.

  However, since the radiating portion 81 is L-shaped, the directivity of the radiating portion as a whole is slightly bent from the longitudinal direction, and is oriented as shown by the solid arrow line 85.

  Next, the configuration of the alignment plate 12 will be described. In particular, FIG. 4 shows a view seen from the direction of the solid arrow 13 in FIG. 1. FIG. 4 shows a case where the end 83 of the radiating portion 81 of the right rotating antenna 8 is closest to the matching plate 12. .

  The alignment plate 12 is made of a plate made of a conductive material such as stainless steel, iron, or a plated steel plate, and is integrated on the bottom surface 31 of the heating chamber by spots or caulking. As shown in FIG. 1, the alignment plate 12 is disposed between the plurality of rotating antennas 8 and 8. In particular, the locus of the outer periphery of the antenna 8 on the right side of FIG. When expressed, the longitudinal direction (30 mm) is arranged in the tangential direction.

  As shown in FIG. 4, the alignment plate 12 has a bottom 121 integrated on the bottom surface 31 of the heating chamber, a central portion 122 in the vertical direction, and a tip portion bent toward the radiating portion 81 side of the right rotating antenna 8. 123. Here, the radiation part 81 is at a distance of 10 mm from the bottom surface 31 of the heating chamber, the height of the central part 122 is 14 mm, the bending dimension of the tip part 123 is 5 mm, and the horizontal distance from the tip part 123 to the radiation part 81 is 4 mm. Further, as shown in FIG. 1, the longitudinal direction is 30 mm.

Next, the effect of the alignment plate 12 will be described. FIG. 5 shows temperature data when 15 frozen springs were heated at 800 W for 3 minutes, FIG. 5 (a) shows a state without the alignment plate 12, FIG.
b) shows the result with the alignment plate 12 present. The numerical value shown in the figure is the temperature of the central part of each of the springs after the end of heating, and the temperature difference from the 15 highest to the lowest is 31K in FIG. 5 (a) and 22K in FIG. 5 (b). The unevenness of temperature was improved by the plate 12. Further, when the alignment plate 12 in FIG. 5 (a) is not present, the two right back vertigos are attached by overcooking, and the portion of the shaded portion 15 is slightly hardened, but when the alignment plate 12 in FIG. 5 (b) is present. That didn't happen. That is, the matching plate 12 eliminates the local overcooking of the display. By the way, when the positional relationship among the vertigo, the rotating antennas 8 and 8, the outer periphery 14 and the alignment plate 12 is described in an overlapping manner, it becomes as shown in FIG. 6, and the overcook hatched portion 15 shown in FIG. 14 is the place through which the end 83 of the right rotating antenna 8 passes. Therefore, it is considered that local overcooking could be prevented by disposing at least a part of the microwaves in this vicinity so as to reflect at least a part of the microwave and avoid electric field concentration. By the way, the outer periphery 14 of the end 83 of the rotating antenna 8 passes through the vicinity of other springs, and it is not surprising that overcooking occurs on the outer periphery of the left antenna. However, considering the reason why only the hatched portion 15 is overcooked, this is not determined only by the rotating antenna, but the heating chamber of the microwave oven is a cavity resonator in which microwaves are confined, and standing waves also occur. It is considered that the place where the standing wave is strong and the tip of the antenna also passes is most likely to be overcooked.

  In summary, in the present embodiment, since the matching plate 12 is disposed between the plurality of rotating antennas 8 and 8, at least a part of the microwaves when the rotating antennas 8 and 8 face each other can be reflected, and as a result As a result, it is possible to disperse the electric field concentration in the vicinity of the end 83 of the rotating antennas 8 and 8 and to prevent local overcooking of the mainspring.

  In particular, since the matching plate 12 is arranged in a tangential direction with respect to the outer periphery 14 of the right rotating antenna 8, the matching plate 12 faces the right rotating antenna 8, and the microscopic radiation emitted from the right rotating antenna 8 is obtained. Waves can be effectively reflected, and the electric field concentration near the end 83 of the right rotating antenna 8 can be dispersed to prevent local overcooking at the right back of the spiral.

  Further, the effect of the alignment plate 12 can be further enhanced by the configuration in which the alignment plate 12 has the tip portion 123 facing the right rotation antenna 8 side. This is because the microwave radiated from the end portion 83 of the rotating antenna 8 is reflected by the central portion (standing wall portion) 122 of the matching plate 12 to suppress the reflected wave upward, and directly from the end portion 83 of the rotating antenna 8. This is presumed to suppress a part of the microwave radiated obliquely upward.

  Furthermore, the effect of the alignment plate 12 can be enhanced most by the configuration in which the control unit controls the direction of the directivity of the right rotating antenna 8 to stop toward the alignment plate 12.

  The meaning of arranging the matching plate 12 between the plurality of rotating antennas 8 and 8 includes the arrangement shown in FIG. 1, and if the matching plate 12 is located on the other antenna side when viewed from one antenna, it is somewhat. It is considered effective.

  In addition, the meaning that the rotating antennas 8 and 8 face each other is typified by the orientation as shown in FIG. 1, for example. However, although the directivity of the antenna is strong in the direction of the solid arrow 85, it has a certain width. Since the wave is radiated, it is not limited to the direction of FIG. 1, but if it is directed to the other antenna side than the perpendicular direction (the solid arrow 85 is upward or downward in FIG. 1) It is considered that there is some effect. In particular, in the case of a patch antenna, the directivity becomes stronger in the longitudinal direction, so it is considered that it is effective if the longitudinal direction is generally directed to another antenna side rather than a right angle.

  FIG. 7 is a plan view showing a modified example of the radiating portion of the rotating antenna. FIG. 7A shows a short side formed in a sickle shape, thereby increasing the creeping length of the short side end, The directivity of the microwave radiated from the tip side is strengthened. Further, (b) forms a short side along the T-shape, thereby further increasing the creeping length of the short side end portion and strengthening the directivity of the microwave radiated from the end tip side. . (C) By increasing the creeping length of the short side end portion by narrowing the short side into a pickle shape, the width of the short side is narrowed to concentrate the electric field of the microwave and improve the radiation directivity. It is what.

(Embodiment 2)
FIG. 8: is a figure which shows schematic structure of the microwave oven which is a microwave heating device of embodiment which concerns on this invention, and is the plane sectional view seen from upper direction.

  The microwave oven shown in FIG. 8 has a configuration in which the waveguide 2 is branched into a T-shape, and the rotary antennas 16 and 16 have a disk-like outer shape and have a strong directivity mainly on the side of the punched hole 17 to provide microwaves. (Slot antenna). The alignment plate 18 has two bottom portions 181 integrated on the heating chamber bottom surface 31 and a central portion 182 in the vertical direction, and unlike the first embodiment, the alignment plate 18 does not have a tip portion. Yes. Further, the matching plate 18 has a symmetrical shape so as to affect both antennas, and is arranged at an equal distance from both antennas.

  Although various embodiments of the present invention have been described above, the present invention is not limited to the matters shown in the above-described embodiments, and those skilled in the art can make modifications and applications based on the description and well-known techniques. This is also the scope of the present invention, and is included in the scope of seeking protection.

  In particular, the antenna may have a plurality of different antennas or a rotating waveguide. It is also easy to arrange a plurality of alignment plates.

  The microwave heating device of the present invention has an effect of preventing local overcooking when controlling the heating distribution by the orientation of a plurality of rotating antennas, and a microwave oven, a microwave oven as a cooking utensil using microwaves, It is useful for various dielectric heating and thawing devices, semiconductor devices using microwaves, heating devices in industrial fields such as drying devices, ceramic heating, sintering or biochemical reaction.

Plan sectional drawing which shows schematic structure of the microwave heating apparatus in Embodiment 1 of this invention Same sectional view showing schematic configuration of microwave heating apparatus The top view which shows the shape of the rotation antenna of the microwave heating device Front view showing the shape of the matching plate of the microwave heating apparatus (A) Characteristic diagram showing temperature distribution of the mainspring of the conventional microwave heating device (b) Characteristic diagram showing temperature distribution of the mainspring of the microwave heating device in the embodiment of the present invention Plan view showing arrangement of rotating antenna, matching plate, and spring (A) (b) (c) is a top view which shows the rotating antenna structure of the microwave heating apparatus in other embodiment of this invention. Plan sectional drawing which shows schematic structure of the microwave heating apparatus in Embodiment 2 of this invention (A) Front sectional view showing a schematic configuration of a conventional microwave heating apparatus (b), (c) is a plane sectional view showing a schematic configuration of the microwave heating apparatus

Explanation of symbols

1 Magnetron (microwave generator)
2 Waveguide 3 Heating chamber 4 Food (object to be heated)
8, 16 Rotating antenna 9 Motor (drive unit)
10 Control unit 12, 18 Alignment plate 123 Tip

Claims (4)

A microwave generation unit that generates a microwave, a waveguide that propagates the microwave from the microwave generation unit, a heating chamber that houses an object to be heated by the microwave, and the heating from the waveguide A plurality of rotating antennas that radiate the microwaves to the chamber, a driving unit that drives the rotating antennas, a control unit that controls the driving unit to control the direction of the rotating antennas, and the plurality of rotating antennas. A microwave heating apparatus comprising a matching plate made of a conductive material integrated on the wall surface of the heating chamber. The microwave heating apparatus according to claim 1, wherein the matching plate is arranged in a tangential direction with respect to the outer periphery of the rotating antenna. The microwave heating device according to claim 1, wherein the matching plate has a tip portion facing the rotating antenna. The microwave heating apparatus according to claim 1, wherein the control unit is configured to control the rotating antenna so that the direction having strong directivity is stopped toward the matching plate.