JP2008166092A - Microwave heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to carry out intensive heating of a food by optimizing the distance between a plurality of rotary antennas. <P>SOLUTION: The microwave heating device comprises a magnetron 2, a waveguide 3, a heating chamber 4 of horizontal long shape, a placing table 5 to place a heating object, an antenna space 6, rotary antennas 8, 9 which are arranged at symmetrical positions to the center in horizontal direction of the heating chamber 4 in order to radiate microwave to the heating chamber 4, motors 10a, 10b to drive the rotary antennas 8, 9, and a control means 11 to control rotation and stopping of the motors 10a, 10b. The waveguide 3 is branched at a position equivalent to 1/4 (nearly 44 mm) of a waveguide wavelength from the center of the heating chamber 4, and each distance from the magnetron 2 to rotary antennas 8, 9 has a difference equivalent to 1/4 (nearly 44 mm) of the waveguide wavelength. <P>COPYRIGHT: (C)2008,JPO&INPIT

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 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 the antenna is driven to rotate. However, in recent years, as a method for improving the uniformity of heating, there is provided 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, only milk is heated. 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, such as when simultaneously heating frozen food and food at room temperature, only low-temperature food is concentrated. You may want to heat. In addition, if you want to heat only the heated food in a concentrated manner, such as a boxed lunch box, where a single container contains unheated foods such as pickles, salads, and desserts, and heated foods such as rice and side dishes 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, with regard to localized heating, for example, a rotating antenna 27a and a rotating antenna 27b having the same shape are arranged symmetrically with respect to the center of the heating chamber 24 as in a microwave oven 21 shown in FIG. The central heating can be realized by stopping the strong directivity portion 29a of the rotating antenna 27a and the strong directivity portion 29b of the rotating antenna 27b in the direction in which they are to be locally heated.

  However, in actuality, the object to be heated placed between the rotating antenna 27a and the rotating antenna 27b with the highly directional part 29a of the rotating antenna 27a and the highly directional part 29b of the rotating antenna 27b facing each other is arranged. When an experiment was conducted to determine whether or not central heating could be performed, sufficient results could not be obtained in terms of local central heating. This is considered to be caused by radio waves repelled or interfered between the rotating antenna 27a and the rotating antenna 27b facing each other. I thought it was necessary to solve this problem.

  On the other hand, for communication antennas, the directivity viewed from a distance far enough away from the antenna in an open space has strong directivity in the vertical direction when the antenna length is half-wavelength, and the front and back when the antenna length is equal to the wavelength. It is known to have the same strong directivity in each direction. However, even if this is applied to a microwave oven, the heating chamber of the microwave oven is a sealed space, so that radio waves are reflected and become standing waves, and the distance from the antenna to the object to be heated is short. It is not possible to simply apply a communication antenna.

  The present invention has been made in view of the above-described conventional circumstances, and by optimizing the distance between a plurality of rotating antennas, a microwave capable of centrally heating an object to be heated placed between the rotating antennas. An object is to provide a heating device.

  The microwave heating apparatus according to the present invention includes a microwave generating unit that generates a microwave having a predetermined wavelength, a waveguide that propagates the microwave from the microwave generating unit, and an object to be heated by the microwave. A heating chamber to be stored; a first antenna that radiates the microwave from the waveguide to the heating chamber; a second antenna that radiates the microwave from the waveguide to the heating chamber; Drive means for driving each of the first and second antennas, and control means for controlling the direction of the antenna by controlling the drive means, between the microwave generation means and the first antenna And a difference in distance between the microwave generating means and the second antenna is different from a value that is an integral multiple of 1/2 of the guide wavelength of the microwave that propagates through the waveguide. With what That.

  With this configuration, the phase of the microwaves radiated from the first and second antennas when facing each other is shifted by half a wavelength, so that the strength is weakened by canceling each other at the antinodes and nodes of the microwaves. Since it can do, the centralized heating to the to-be-heated object put between the 1st and 2nd antenna is attained.

  According to another aspect of the present invention, in the above microwave heating apparatus, a distance between the microwave generation unit and the first antenna, and between the microwave generation unit and the second antenna. A structure in which the difference in distance is a value that is an odd multiple of approximately ¼ of the guide wavelength is also included.

  With this configuration, the phases of the microwaves radiated from the first and second antennas when facing each other are not shifted by a half wavelength, so that the first and second antennas do not cancel each other at the antinodes and nodes of the microwaves. Centralized heating can be performed on an object to be heated placed between the second antennas.

  Furthermore, as one aspect of the present invention, the above microwave heating apparatus includes a configuration in which the waveguide has a T-shaped branch shape in a direction in which the microwave propagates.

  With this configuration, the phases of the microwaves radiated from the first and second antennas when facing each other are not shifted by a half wavelength, so that the first and second antennas do not cancel each other at the antinodes and nodes of the microwaves. Centralized heating can be performed on an object to be heated placed between the second antennas.

  Further, as one embodiment of the present invention, in the above microwave heating apparatus, the waveguide may include a linear configuration in a direction in which the microwave propagates.

  With this configuration, the phases of the microwaves radiated from the first and second antennas when facing each other are not shifted by a half wavelength, so that the first and second antennas do not cancel each other at the antinodes and nodes of the microwaves. Centralized heating can be performed on an object to be heated placed between the second antennas.

  Further, as one aspect of the present invention, in the above microwave heating apparatus, the waveguide has a width-direction dimension of approximately 85 mm, and a distance between the microwave generation unit and the first antenna; A configuration in which the difference between the distance between the microwave generation means and the second antenna is 110 mm or more and 150 mm or less is also included.

  With this configuration, the phases of the microwaves radiated from the first and second antennas when facing each other are not shifted by a half wavelength, so that the first and second antennas do not cancel each other at the antinodes and nodes of the microwaves. Centralized heating can be performed on an object to be heated placed between the second antennas.

  ADVANTAGE OF THE INVENTION According to this invention, the microwave heating apparatus which can concentrately heat the to-be-heated material placed between each antenna by optimizing the distance between several antennas can be provided.

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

(First embodiment)
The first embodiment of the present invention exemplifies a microwave oven that is a microwave heating device using a waveguide having a T-shaped branch. 1A and 1B are diagrams showing a schematic configuration of a microwave oven according to a first embodiment of the present invention, in which FIG. 1A is a front sectional view seen from the front, and FIG. 1B is a plan sectional view seen from above.

  1A and 1B, a microwave oven 1 according to this embodiment includes a magnetron 2 that is a typical microwave generation unit, a waveguide 3 that propagates microwaves emitted from the magnetron 2, A heating chamber 4 connected to an upper portion of the waveguide 3; a mounting table 5 which is fixed in the heating chamber 4 and on which the object to be heated 13 is mounted; an antenna space 6 which is formed below the mounting table 5; The substantially circular coupling holes 7a and 7b provided on the bottom surface symmetrical to the horizontal center of the heating chamber 4, and the first rotating antenna 8 disposed on the mounting table 5 and rotatable about the coupling hole 7a. And the second rotary antenna 9 that is rotatable about the coupling hole 7b and has substantially the same shape as the first rotary antenna 8, and the first rotary antenna 8 is driven through the fitted drive shaft. A motor 10a, a motor 10b for driving the second rotating antenna 9, and a motor; Rotation of the motor 10a · motor 10b, a configuration and a control unit 11 for controlling the stop.

  Moreover, the microwave oven 1 of this embodiment is provided with the setting means 12 in the front of the heating chamber 4, and a user can select a cooking menu according to a foodstuff or cooking content. Based on the selection result, the control means 11 controls the magnetron 2 to generate and stop the microwaves, and controls the motors 10a and 10b to control the rotation and stop of the rotating antennas 8 and 9. Thereby, the food 13 mounted on the mounting table 5 can be heated and cooked.

  The first rotating antenna 8 includes a radiating portion 81 made of a conductive material having a longitudinal direction, a substantially cylindrical shape that penetrates the coupling hole 7a, is eccentric in the longitudinal direction of the radiating portion 81, and is electrically and mechanically integrated. It is comprised from the coupling | bond part 82 which consists of a conductive material of a shape.

  The second rotating antenna 9 includes a radiating portion 91 made of a conductive material having a longitudinal direction and a substantially cylindrical shape that penetrates the coupling hole 7b and is eccentric in the longitudinal direction of the radiating portion 91 and is electrically and mechanically integrated. It is comprised from the coupling | bond part 92 which consists of a conductive material of a shape. The first rotating antenna 8 and the second rotating antenna 9 are arranged at a pitch of 155 mm at symmetrical positions with respect to the horizontal center of the heating chamber 4 as shown in FIG. Thereby, the shape of the radiation part 81 and the radiation part 91 changes with respect to the direction of rotation, and emits microwaves with strong directivity in the direction of the end part on the longer side in the longitudinal direction.

  The waveguide 3 has a substantially inverted T-shape when viewed from above, and has a width of approximately 85 mm as shown in FIG. 2, which will be described later, and a microwave guide wavelength λg of 1 in the horizontal direction of the heating chamber 4. It is a shape branched at a position shifted by / 4 (approximately 44 mm). Due to this shape, a difference corresponding to 1/4 (approximately 44 mm) of the in-tube wavelength λg occurs between the distance from the magnetron 2 to the coupling portion 82 and the distance from the magnetron 2 to the coupling portion 92, and the first rotation The microwaves radiated from the antenna 8 and the second rotating antenna 9 have phases shifted by ¼ wavelength.

  With these configurations, the rotation of the first rotating antenna 8 and the second rotating antenna 9 is controlled by the control means 11, and the long ends of the radiating portion 81 and the radiating portion 91 are opposed to each other and stopped. By doing it, the foodstuff 13 mounted in the center of the mounting base 5 can be concentratedly heated.

  FIG. 2 shows the distance between the distance from the magnetron 2 to the coupling portion 82 and the distance from the magnetron 2 to the coupling portion 92 when the long side ends of the radiation portion 81 and the radiation portion 91 face each other. If there is a difference corresponding to 1/4 of the in-tube wavelength λg, a verification result that can enhance the radiation directivity is shown.

  FIG. 2A and FIG. 2B show the results of evaluation performed using the conventional waveguide 23 branched bilaterally and prepared for comparison. The distance from the magnetron 22 to the first rotating antenna 27a is equal to the distance from the magnetron 22 to the second rotating antenna 27b. For this reason, microwaves having the same phase are radiated from the first rotating antenna 27a and the second rotating antenna 27b facing each other. Reference numeral 28a denotes a coupling portion made of a substantially cylindrical conductive material that penetrates the coupling hole and is electrically and mechanically integrated with the rotary antenna 27a. Reference numeral 28b denotes a coupling portion made of a substantially cylindrical conductive material that penetrates the coupling hole and is electrically and mechanically integrated with the rotating antenna 27b.

  The black-and-white photograph shown in FIG. 2B shows a heating distribution of a load (paste) placed between the first rotating antenna 27a and the second rotating antenna 27b facing each other. As shown in FIG.2 (b), the cloudy part W which shows that it heated and the temperature rose is disperse | distributed right and left. Therefore, it can be seen that it is difficult to realize concentrated heating in the waveguide 23 branched bilaterally. In black and white photographs, the black part means that the glue has not changed from the transparent state.

  On the other hand, FIGS. 2C and 2D show that the distance between the magnetron 2 and the coupling portion 82 and the distance from the magnetron 2 to the coupling portion 92 is ¼ of the guide wavelength λg. The evaluation results when there is a corresponding difference are shown.

  In FIG. 2C, the waveguide 2 is branched at a position shifted in the lateral direction of the heating chamber 4 by 1/4 (approximately 44 mm) of the guide wavelength λg. As a result, a difference corresponding to 1/4 (approximately 44 mm) of the in-tube wavelength λg occurs between the distance from the magnetron 2 to the coupling portion 82 and the distance from the magnetron 2 to the coupling portion 92. For this reason, the first rotating antenna 8 and the second rotating antenna 9 facing each other radiate microwaves whose phase is shifted by 1/4 (approximately 30 mm) of the wavelength λ.

  The black-and-white photograph shown in FIG. 2 (d) shows the heating distribution of the load (paste) placed between the first rotating antenna 8 and the second rotating antenna 9 facing each other. The cloudiness part which shows that the temperature rose due to heating is concentrated in the center. Thereby, when there is a difference corresponding to 1/4 of the in-tube wavelength λg between the distance from the magnetron 2 to the coupling portion 82 and the distance from the magnetron 2 to the coupling portion 92, concentrated heating is possible. Has been demonstrated.

  The first rotating antenna 8 and the second rotating antenna 9 facing each other are not limited to radiating microwaves whose phases are shifted by ¼ of the wavelength λ, but are coupled from the magnetron 2. The same applies to the case where a difference corresponding to an odd multiple of 1/4 of the guide wavelength occurs between the distance to the portion 82 and the distance from the magnetron 2 to the coupling portion 92.

  As described above, according to the microwave heating apparatus according to the first embodiment of the present invention, in the substantially T-shaped waveguide, the first and second from the magnetron due to the shift of the branch position. When a difference corresponding to an odd multiple of 1/4 of the guide wavelength λg occurs in the distance to the rotary antenna, the micro of the phase shifted by 1/4 wavelength of the guide wavelength from the first rotary antenna and the second rotary antenna. A wave is emitted.

  Thereby, the food placed in the center of the mounting table can be centrally heated by controlling the rotation so that the first and second rotating antennas stop at positions facing each other.

(Second Embodiment)
In the second embodiment of the present invention, a microwave oven of a microwave heating apparatus using a linear waveguide is illustrated. 3A and 3B are diagrams showing a schematic configuration of the microwave oven according to the embodiment of the present invention, in which FIG. 3A is a front sectional view seen from the front, and FIG. 3B is a plan sectional view seen from above. The same components as those in FIG.

  3A and 3B, the microwave oven 20 of the present embodiment includes a first rotary antenna 18 and a second rotary antenna 19 that are substantially I-shaped, and a micro-wave radiated from the magnetron 2. It is the structure provided with the linear waveguide 31 which propagates a wave.

  As shown in the schematic diagram of FIG. 4, the first rotating antenna 18 and the second rotating antenna 19 are arranged at positions L1 and L2, respectively, with a difference in distance, that is, a mutual distance. A certain (L1-L2) is configured as an odd multiple of 1/4 of the in-tube wavelength λg of the microwave propagating through the waveguide 31, for example, 3/4 of the in-tube wavelength.

  With this configuration, the first rotating antenna 18 and the second rotating antenna 19 radiate microwaves with a ¼ wavelength phase shifted. Therefore, similarly to the first embodiment described above, the rotation is controlled so that the first rotating antenna 18 and the second rotating antenna 19 are stopped at the positions facing each other, so that the center of the mounting table is set. It becomes possible to heat the specific food that has been placed. Note that specific dimensions of the present embodiment will be described. When the widthwise dimension of the waveguide is approximately 85 mm, the guide wavelength is about 175 mm, and 3/4 of the guide wavelength is about 133 mm. However, even if it is not exactly 133 mm, it is considered that the effect can be exhibited if it is far from an integral multiple of 1/2 of the guide wavelength and close to an odd multiple of 1/4. In other words, it is considered effective if it is far from 175 mm which is 1/2 of the guide wavelength and 175 mm which is 2/2 of the guide wavelength and is close to 133 mm which is 3/4 of the guide wavelength. The effect was confirmed by the dimensions. Effectively, it is considered that a considerable effect can be expected when the thickness is 110 mm or more and 150 mm or less.

  As described above, according to the microwave heating apparatus according to the second embodiment of the present invention, in the linear waveguide, the distance from the magnetron to the first and second rotating antennas is set. When a difference corresponding to an odd multiple of 1/4 of the guide wavelength occurs, microwaves having a phase shifted by 1/4 wavelength of the guide wavelength are radiated from the first and second rotating antennas.

  Thereby, the food placed in the center of the mounting table can be centrally heated by controlling the rotation so that the first and second rotating antennas stop at positions facing each other.

  The microwave heating apparatus of the present invention has an effect of centrally heating an object to be heated placed between rotating antennas by optimizing the distance between the rotating antennas, and uses microwaves. Microwave ovens, microwave ovens, various dielectric heating and thawing devices as cooking utensils, heating devices in industrial fields such as semiconductor devices using microwaves, drying devices, ceramics heating, sintering or biochemistry It is useful for applications such as reaction.

(A) Front sectional view showing a schematic configuration of the microwave heating device according to the first embodiment of the present invention (b) Plan sectional view showing a schematic configuration of the microwave heating device according to the first embodiment of the present invention (A) Schematic configuration diagram of conventional microwave heating device (b) Diagram showing experimental results of conventional microwave heating device (c) Schematic configuration diagram of microwave heating device in first embodiment of the present invention (d) ) Diagram showing experimental results of the microwave heating apparatus according to the first embodiment of the present invention. (A) Front sectional view showing a schematic configuration of a microwave heating device according to a second embodiment of the present invention (b) Plane sectional view showing a schematic configuration of a microwave heating device according to a second embodiment of the present invention The schematic diagram which shows the positional relationship of the magnetron and rotary antenna of the microwave heating device in the 2nd Embodiment of this invention. Plan sectional view showing a schematic configuration of a conventional microwave heating apparatus

Explanation of symbols

1,20 Microwave oven (microwave heating device)
2 Magnetron (microwave generation means)
3 T-shaped branched waveguide 4 Heating chamber 5 Mounting table 6 Antenna space 7a, 7b Coupling hole 8, 9, 18, 19 Rotating antenna 10a, 10b Motor 11 Control means 12 Setting means 31 Linear waveguide

Claims (5)

Microwave generation means for generating microwaves of a predetermined wavelength;
A waveguide for propagating the microwave from the microwave generating means;
A heating chamber for storing an object to be heated by the microwave;
A first antenna that radiates the microwave from the waveguide to the heating chamber;
A second antenna that radiates the microwave from the waveguide to the heating chamber;
Driving means for driving each of the first and second antennas;
Control means for controlling the direction of each antenna by controlling the driving means;
Have
The difference between the distance between the microwave generating means and the first antenna and the distance between the microwave generating means and the second antenna is an in-tube propagation of the microwave through the waveguide. A microwave heating apparatus having a configuration different from an integral multiple of 1/2 of the wavelength.   The difference between the distance between the microwave generation means and the first antenna and the distance between the microwave generation means and the second antenna is an odd multiple of approximately 1/4 of the guide wavelength. The microwave heating device according to claim 1, wherein the microwave heating device is configured to have a value.   The microwave heating apparatus according to claim 2, wherein the waveguide has a shape branched in a T shape in a direction in which the microwave propagates.   The microwave heating apparatus according to claim 2, wherein the waveguide is configured to be linear in a direction in which the microwave propagates. The waveguide has a width direction dimension of about 85 mm,
The difference between the distance between the microwave generation means and the first antenna and the distance between the microwave generation means and the second antenna is 110 mm or more and 150 mm or less. Item 5. The microwave heating apparatus according to Item 3 or Item 4.