JPH07161469A - High frequency heating device - Google Patents

Abstract

PURPOSE:To enable the selection of an excitation port position corresponding to an item to be cooked, and to cope with a local heating, and to evenly heat the material to be heated at a high efficiency. CONSTITUTION:In an annular rectangular waveguide 1, a separation line 8 is formed at a nearly central part of the H surface of the rectangular waveguide, and irradiation of the mu wave into a heating chamber 17 is very small. Almost of the mu wave excited by a magnetron 18 is radiated from an excitation port 11 to a metal heating chamber 17. The excitation port 11 can be placed near a material 21 to be heated to perform the local heating by providing the excitation port 11 in the bottom surface of the heating chamber 17. In the case where this characteristic is utilized for heating of the liquid 21 in a tall container 20, the only liquid of the bottom part of the container 20 is heated to generate a heat convection, and the liquid is agitated by the heat convection to perform the heating with a little temperature difference. The mu wave radiated from the excitation port 1 at this stage is not reflected by the wall surface of the heating chamber and absorbed by the material 21 to be heated at a high efficiency to perform the efficient heating. In the case of boil-over, the material to be heated is collected in a circular recessed part of a central part of a metal bottom plate 4 to reduce the influence to the mu wave.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency heating apparatus for irradiating an object to be heated housed in a heating chamber with microwaves for dielectric heating.

[0002]

2. Description of the Related Art As a conventional high frequency heating apparatus, there is one disclosed in, for example, Japanese Patent Laid-Open No. 5-54965.
In this high-frequency heating device, a power feed port is opened in the substantially central portion of the bottom surface of the heating chamber, and the microwave oscillated by the magnetron is guided to this power feed port through a waveguide. Further, a metal rotary shaft is provided upright in the power supply port, and a roller is connected to the metal rotary shaft via a metal stick to form a roller stick. Then, the roller stay is rotated around the metal rotation shaft to rotate the non-metal turntable placed on the roller, and the microwave supplied to the power supply port is fed by the roller stay that functions as a rotating radiation antenna. It radiates into the heating chamber. Further, the second power supply port is provided on the top surface or the side surface of the heating chamber so that the object can be efficiently heated even when the shape of the object to be heated is large.

[0003]

A conventional high-frequency heating device is provided with a metal rotary shaft, a metal stay and a roller stay having a roller between the bottom of the heating chamber and the turntable, and serves as a rotary radiation antenna. Since the microwave is radiated into the heating chamber by rotating this working roller stay, the microwave radiation area is large and only the bottom of the liquid is heated when heating a tall liquid such as a sake can. Things are difficult and the temperature difference between the top and bottom becomes large.
Also, there is a second power supply port provided on the top or side,
It is not possible to select the heating that corresponds to the cooking item such as a tall object to be heated or a flat object, and the same heating is performed. Further, since the roller stay is used, it is difficult to incorporate the weight sensor.

The present invention has been made in view of the above circumstances, and it is possible to select the position of the excitation port corresponding to the item to be cooked, and it is possible to sufficiently cope with local heating of liquid or the like contained in a tall container. An object of the present invention is to provide a high-frequency heating device capable of uniformly heating these objects to be heated with high efficiency, downsizing, and incorporating a weight sensor.

[0005]

In order to solve the above-mentioned problems, the present invention firstly proposes that a microwave oscillated by a microwave power source is propagated through a waveguide and is radiated from an excitation port to a heating chamber. In a high-frequency heating device for microwave-heating an object to be heated housed in the heating chamber, at least a part of the waveguide is formed in an annular shape, and the annular portion is fixed to the heating chamber side along the circumferential direction. The gist of the present invention is that it is divided into an annular part and a rotatable movable part, the microwave power source is connected to the fixed annular part, and the excitation port is connected to the movable annular part.

Secondly, the microwave oscillated by the microwave power source is propagated through the waveguide and is radiated from the excitation port to the heating chamber,
In a high-frequency heating device for microwave-heating an object to be heated housed in the heating chamber, the waveguide is constituted by a rectangular waveguide, and at least a part of the rectangular waveguide is formed in an annular shape and the annular portion is formed. Is separated into a fixed annular portion fixed to the heating chamber side and a rotatable movable annular portion along the circumferential direction at a substantially central portion of the H surface, and the microwave power source is connected to the fixed annular portion, The gist is that the excitation port is connected to the movable annular portion.

Thirdly, the microwave oscillated by the microwave power source is propagated through the waveguide and radiated from the excitation port to the heating chamber,
In a high frequency heating device for microwave heating an object to be heated housed in the heating chamber, the waveguide is constituted by a rectangular waveguide, and at least a part of the rectangular waveguide is annular and the H surface is annular. Is formed so as to form a right angle with the central axis, and the annular portion is separated into a fixed annular portion fixed to the heating chamber side and a movable annular portion that is rotatable along the circumferential direction at the substantially central portion of the H surface. ,
The gist is that the microwave power source is connected to the fixed annular portion, and the excitation port is connected to the movable annular portion.

Fourthly, the microwave oscillated by the microwave power source is propagated through the waveguide and radiated from the excitation port to the heating chamber,
In a high frequency heating device for microwave heating an object to be heated housed in the heating chamber, the waveguide is constituted by a rectangular waveguide, and at least a part of the rectangular waveguide is annular and the H surface is annular. Is formed so as to form a right angle with the central axis, and the annular portion is separated into a fixed annular portion fixed to the heating chamber side and a movable annular portion that is rotatable along the circumferential direction at the substantially central portion of the H surface. ,
The microwave power source is connected to the fixed annular portion, and the excitation port is connected to a waveguide wall forming an E surface of the movable annular portion with or without a waveguide. .

Fifthly, the microwave oscillated by the microwave power source is propagated through the waveguide and radiated from the excitation port to the heating chamber,
In a high-frequency heating device for microwave-heating an object to be heated housed in the heating chamber, the waveguide is constituted by a rectangular waveguide, and at least a part of the rectangular waveguide is annular and the E surface is annular. Is formed so as to form a right angle with the central axis, and the annular portion is separated into a fixed annular portion fixed to the heating chamber side and a movable annular portion that is rotatable along the circumferential direction at the substantially central portion of the H surface. ,
The gist is that the microwave power source is connected to the fixed annular portion, and the excitation port is connected to the movable annular portion.

Sixth, the microwave oscillated by the microwave power source is propagated through the waveguide and radiated from the excitation port to the heating chamber,
In a high-frequency heating device for microwave-heating an object to be heated housed in the heating chamber, the waveguide is constituted by a rectangular waveguide, and at least a part of the rectangular waveguide is annular and the E surface is annular. Is formed so as to form a right angle with the central axis, and the annular portion is separated into a fixed annular portion fixed to the heating chamber side and a movable annular portion that is rotatable along the circumferential direction at the substantially central portion of the H surface. ,
The microwave power source is connected to the fixed annular portion, and the excitation port is connected to a waveguide wall forming an H plane in the movable annular portion with or without a waveguide. .

Seventh, in any one of the second to sixth structures, the electrical length of one round of the annular portion is approximately n · λg / 2.
(However, n is an arbitrary integer, λg is a guide wavelength).

Eighth, in any one of the second to sixth configurations, the electrical length of one round of the annular portion is (n + (1 /
m)). multidot..lamda.g (where n and m are arbitrary integers, .lamda.g is a guide wavelength), and the gist is that m excitation ports are provided.

Ninth, the gist of any one of the second to eighth configurations is that the rectangular waveguide is a ridge waveguide.

Tenth, in any one of the above second to eighth configurations, a bent portion having a required width is formed in the pipe along a separation portion substantially in the center of the H surface of the annular portion. To do.

[0015]

In the above structure, first, it is possible to freely select the position of the exciting port by appropriately rotating the movable annular portion according to the item to be cooked. The bottom center excitation port is realized by providing the annular waveguide on the bottom surface of the heating chamber, setting the movable annular portion inside, and positioning the excitation port at the center of rotation through the waveguide or the like. As a result, it becomes possible to locally heat the liquid or the like contained in the tall container uniformly with high efficiency. Further, even when the annular waveguide is provided on the bottom surface of the heating chamber as described above, the weight sensor can be incorporated in the rotation center shaft portion.

Secondly, the waveguide is a rectangular waveguide, and the fixed annular portion and the movable annular portion are separated along the circumferential direction at the substantially central portion of the H-plane of the rectangular waveguide, thereby separating them. Radiation of microwaves from the section becomes very small, and almost all of the microwaves from the microwave power source can be emitted from the excitation port. Therefore, local heating or the like according to the above-mentioned cooking item is appropriately realized.

Third, by forming the annular rectangular waveguide so that its H surface is perpendicular to the central axis of the annular rectangular waveguide, the annular rectangular waveguide becomes flat and its top plate is placed on the bottom surface of the heating chamber. It can also be used for ease of incorporation into the bottom of the heating chamber. Therefore, it becomes possible to easily realize a local heating structure for liquid or the like contained in a tall container.

Fourthly, an annular rectangular waveguide is formed so that its H surface is perpendicular to the central axis of the annular shape, and the excitation port has the waveguide on the E wall of the movable annular portion. By connecting with or without intervening, it becomes easy to make the top plate of the annular rectangular waveguide also serve as the bottom of the heating chamber to be incorporated into the bottom of the heating chamber as described above, and the excitation port of the movable annular portion A structure for positioning near the center of rotation is easily realized.

Fifth, by forming the annular rectangular waveguide so that the E surface thereof is perpendicular to the central axis of the annular rectangular waveguide, the outer diameter of the annular rectangular waveguide is reduced and the rotating plate portion is heated. It can also be used as the side wall of the chamber and can be easily incorporated into the side of the heating chamber.

Sixthly, an annular rectangular waveguide is formed so that its E surface is perpendicular to the central axis of the annular shape, and the excitation port has the waveguide on the waveguide wall forming the H surface in the movable annular portion. By connecting with or without interposing, the rotating plate of the annular rectangular waveguide can be used also as the heating chamber side wall as described above to facilitate installation in the heating chamber side part, and the excitation port can be moved to a movable annular shape. A structure is realized which is located between the part and its center of rotation. Therefore, by rotating the movable annular part, the position of the excitation port on the side wall of the heating chamber can be changed, and the excitation mode can be changed according to the item to be cooked. Cooking is possible.

Seventh, the electrical length of one round of the annular portion is approximately n · λ.
By setting g / 2, there can be n places where the microwave traveling in the clockwise direction and the microwave traveling in the counterclockwise direction in the annular rectangular waveguide have the same phase. When the excitation port is located at this place, the heating chamber is moved to the heating chamber. The microwave output of becomes large. Therefore, by rotating the movable annular portion and switching the excitation port to the position of the n position with the passage of time or the like, it is possible to obtain efficient heating characteristics according to the cooking item.

Eighth, the electrical length of one round of the annular portion is (n +
(1 / m)) · λg, and when m is set to 2 and two excitation ports are arranged at symmetrical positions of the rotation axis so that the phase is shifted by λg / 4, these two excitation ports are complementary. Automatically, one microwave output becomes large, and the other microwave output becomes small. Therefore, regardless of the rotation angle of the movable annular portion, microwave output to the heating chamber is always possible, uniform heating is possible, and it is possible to prevent changes in the operating point for the microwave power source. It will be possible.

Ninth, by using a rectangular waveguide as a ridge waveguide, the cut-off frequency becomes lower than that of a rectangular waveguide having the same external dimensions, and when the microwave of the same frequency is propagated, the guide wavelength λg. Becomes shorter. Therefore, the size can be reduced as compared with the annular waveguide having the same electric length, which is configured by the rectangular waveguide, and the easy assembling property can be obtained.

Tenth, by forming a bent portion having a required width in the tube along the separation portion in the center of the H-plane of the annular portion, it is possible to obtain the same operation as the ridge waveguide.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are views showing a first embodiment of the present invention. FIG. 1 is a perspective view of the waveguide portion, and a part of the waveguide portion is cut away for the sake of clarity and neglect. FIG. 2 is a cross-sectional view of the waveguide portion, and some lines are omitted for clarity. FIG. 3 is a sectional view showing the structure of the main part inside the apparatus. The device configuration will be described with reference to these figures. The metal waveguide upper surface plate 2 also serves as the bottom surface of the heating chamber 17, and constitutes the upper surface (H surface) of the fixed-side annular portion 1a in the annular rectangular waveguide 1. The metal waveguide outer wall surface 3 is connected to the metal waveguide upper surface plate 2 and constitutes an outer surface (E surface) of the fixed side annular portion 1a. The metal bottom plate 4 is connected to the metal waveguide outer wall surface 3 and constitutes the lower surface (H surface) of the fixed side annular portion 1a. The metal waveguide inner wall surface 6 is attached to the metal rotating bottom plate 5 rotatably arranged in the circular recess in the center of the metal bottom plate 4.
And the metallic rotating upper plate 7 is connected to the metallic waveguide inner wall surface 6 to form the movable side annular portion 1b of the annular rectangular waveguide 1. As described above, in the present embodiment, the H-plane of the annular rectangular waveguide 1 is arranged so as to form a right angle with the central axis of the annular rectangular waveguide (the same position as the axis 13 described later), and the annular rectangular waveguide 1 has the H-plane. Fixed-side annular portion 1a fixed to the heating chamber 17 side along the circumferential direction at the separation line 8 in the substantially central portion
And a movable side annular portion 1b which is rotatable. A magnetron 18, which is a microwave power source, is connected to the E surface of the fixed-side annular portion 1a via the waveguide 9. 9a is a port (opening) connected to the magnetron 18. The upper surface of the waveguide 9 is also used as the metal waveguide top plate 2, and the lower surface is also used as the metal bottom plate 4. In addition, the metal waveguide inner wall surface 6 that is the E surface of the movable side annular portion 1b
Exciting port 11 (waveguide 10
Heating chamber side opening) is connected. At the center of the inner side (hereinafter also referred to as the rotor 12) of the annular rectangular waveguide 1 including the metallic rotating bottom plate 5, the metallic waveguide inner wall surface 6, the metallic rotating upper plate 7, the waveguide 10, and the excitation port 11. A support 14 that is detachably fitted to a shaft 13 of a rotary drive system that also serves as a detection shaft of the weight sensor is provided. The shaft 13 is connected to a motor / weight sensor 15. Further, a circular waveguide-shaped choke 16 is provided in order to prevent microwaves from leaking from the hole portion of the metal bottom plate 4 into which the shaft 13 of the rotary drive system is inserted. In FIG. 3, 19 is a turntable,
It is made of a material that can transmit microwaves. Reference numeral 20 denotes a container containing an object to be heated (a liquid in the figure) 21.

Next, the operation of the high-frequency heating device constructed as described above will be described. In the annular rectangular waveguide 1, since the separation line 8 is formed substantially in the center of the H surface of the rectangular waveguide,
Radiation of microwaves from this portion into the heating chamber 17 is very small. For this reason, almost all of the microwaves oscillated by the magnetron 18 is discharged from the excitation port 11 to the metal heating chamber 1
It is radiated to 7. The excitation port 11 is provided on the bottom of the heating chamber 17.
In the case of providing, the excitation port 11 can be placed in the immediate vicinity of the article to be heated 21 (the article 21 to be heated is placed in the vicinity of the excitation port 11), and local heating can be performed. When this characteristic is used for heating the liquid 21 contained in the tall container 20, for example, only the liquid at the bottom of the container 20 is heated, and the heated liquid causes thermal convection and agitates by itself. It is possible to perform heating with a small temperature difference. At this time, the microwave radiated from the excitation port 11 is
7 The rate of being absorbed by the object to be heated 21 without being reflected by the wall surface is high, and efficient heating can be performed. Further, when liquid food is spilled out by microwave oven cooking or the like, the liquid food accumulates in the central circular recess of the bottom plate 4 of metal, so that the influence on the microwave circuit is reduced. In addition, the weight sensor can be used easily even though the excitation port 11 is provided at the center of the bottom surface.

4 to 6 show a second embodiment of the present invention. In the present embodiment, the E-plane of the annular rectangular waveguide is formed so as to form a right angle with the central axis of the annular waveguide, and the H-plane of the movable side annular portion is excited by the waveguide wall through the waveguide. The mouth is connected. FIG. 4 is a perspective view of the waveguide portion, and a part of the waveguide portion is cut away for the sake of clarity and neglect. Figure 5
Is a cross-sectional view of the waveguide portion, and some lines are omitted for clarity. FIG. 6 shows an arrangement of the waveguide portion with respect to the heating chamber. The device configuration will be described with reference to these figures. The port 26a (opening of the waveguide 26) is connected to a microwave power source (not shown). Metal outer wall plate 2
3 has an annular groove portion connected to the waveguide 26, and the fixed side annular portion 22 in the annular rectangular waveguide 22 is formed by this groove portion.
a is configured. A circular recess 23a is provided in the upper portion of the groove that serves as the fixed-side annular portion 22a, and a metallic rotor 24 is configured to rotatably fit into the recess 23a. The rotating plate portion 24a of the rotor 24 is provided in the heating chamber 17
The movable side annular portion 22b is constituted by the groove portion which also serves as the wall surface of the rotary plate portion 24a and which is in contact with the periphery of the rotary plate portion 24a. in this way,
In this embodiment, the E-plane of the annular rectangular waveguide 22 is arranged so as to form a right angle with the central axis of the annular rectangular waveguide (the same position as the rotation axis 29 described later), and the annular rectangular waveguide 22 is substantially centered on the H-plane. A parting line 25 separates the stationary side annular part 22a and the movable side annular part 22b. The waveguide 26 is connected to the waveguide wall forming the H surface of the fixed-side annular portion. Excitation mouth 28
Is opened in the rotary plate portion 24a and is connected to the waveguide wall forming the H surface of the movable side annular portion 22b by the waveguide 27. The center of the rotary plate portion 24a is attached to the rotary drive mechanism 30 via the rotary shaft 29. A rotation angle detector (eg, absolute rotary encoder) is provided on the rotary shaft 29.
31 is connected, the rotation angle of the rotor 24, that is, the excitation port 28.
The rotation position of can be detected. In this embodiment, the excitation port 28 is connected to the waveguide wall of the movable side annular portion 22b via the waveguide 27, but the excitation port 28 is on the rotary plate portion 24a and the movable side annular portion. You may open directly to the E surface of 22b.

Next, the operation of the high-frequency heating device constructed as described above will be described. Since the separation line 25 of the annular rectangular waveguide 22 is formed substantially at the center of the H surface of the rectangular waveguide, the microwave radiation from this portion to the heating chamber 17 is very small. Therefore, almost all of the microwave oscillated by the magnetron is radiated from the excitation port 28 into the heating chamber 17. Further, by rotating the rotor 24, the heating chamber 17
The position of the excitation port 28 on the wall surface can be changed.
Therefore, the excitation mode of the heating chamber 17 can be changed according to the cooking item. For example, drinking sake, warming milk, etc.
In the case of a cooking item in which the liquid 21 is heated in the tall container 20, by moving the excitation port 28 to the lowest position and heating it, heating with less uneven temperature can be performed. In addition, for cooking items such as thawing and heating of Shumai, the exciter port 2
By rotating 8 continuously, the effect of a stirrer fan can be obtained. In this way, by changing the excitation mode of the heating chamber according to the item to be cooked, it is possible to perform cooking with high efficiency and less uneven heating.

FIG. 7 shows a third embodiment of the present invention. FIG. 7 shows a case in which the present embodiment is applied to the annular rectangular waveguide 1 of FIG. 1, and 3.5 λg (n · λg) where the in-tube wavelength of the electrical length of one round of the annular rectangular waveguide 1 is λg. / 2 is set to n = 7). The electrical length of one round is 3.5λ
In order to obtain g, the frequency of the microwave oscillated by the magnetron is set to 2.45 [GHz] and the width of the waveguide is set to 78.
If [mm], the wavelength λg in the tube is about 212 [mm],
3.5λg is 742 [mm]. The radius of this circumference is about 118 mm, and the outer radius r ₂ of the annular rectangular waveguide 1 at this time is 157 mm and the inner radius r ₁ is 79 mm. When the rectangular waveguide is not linear, the calculation of the in-tube wavelength is not so simple as it has been advanced, but the accuracy of this degree is sufficient for the design of the annular portion of about several wavelengths.

As described above, when the electrical length of one round of the annular rectangular waveguide 1 is n.lamda.g / 2, the microwave traveling in the clockwise direction and the microwave traveling in the counterclockwise direction in the annular rectangular waveguide 1 are generated. There can be n in-phase places. When the waveguide 10 connected to the excitation port 11 serving as a microwave outlet is located in this in-phase location, the microwave output to the excitation port 11 increases. That is, n is 7 as shown in this embodiment.
Then, 7 points are obtained that are suitable for microwave output, and n points that are suitable for microwave output are obtained when the electrical length of one round is n · λg / 2. Each of the n positions of the excitation ports 11 has a different excitation mode with respect to the heating chamber, and different heating characteristics (heating patterns) can be obtained. It is possible to obtain a desired heating characteristic by using these alone or by switching them over time and using them in combination.

FIG. 8 shows a fourth embodiment of the present invention. FIG. 8 shows a case where the present embodiment is applied to the annular rectangular waveguide 1 of FIG. 1, and 3.5 λg ((n + ( 1 / m))
・ In λg, n = 3 and m = 2 are set). The first excitation port 32, the second excitation port 33, and two excitation ports are provided. The respective excitation ports 32 and 33 are located symmetrically to each other with respect to a rotation axis (not shown), and the waveguides electrically connected to the respective excitation ports 32 and 33 are connected to the annular rectangular waveguide 1. The position to be shifted is configured so that the phase is shifted by λg / 4. That is, when one is in the antinode of the standing wave, the other is in the node of the standing wave.

As described above, assuming that the electrical length of one round of the annular rectangular waveguide 1 is (n + (1/2)). Lamda.g, the microwave traveling clockwise in the annular rectangular waveguide 1 and the counterclockwise direction. There are (2 × n + 1) places where the proceeding microwaves are in phase. When the waveguide connected to the excitation port serving as the microwave outlet is positioned at this in-phase location, the microwave output to the excitation port becomes large. As shown in the examples, the first,
When the second excitation ports 32 and 33 are provided, one of the two excitation ports has a large microwave output and the other has a small microwave output. In this way, two excitation ports 3
2 and 33 operate complementarily, and microwave output is always possible regardless of the rotation angle of the excitation port. That is, even if the excitation port is rotated while the magnetron is in the operating state, the operating point for the magnetron does not change much. Then, as described in the first embodiment, by combining the local heating characteristic in the case where the excitation port is located substantially in the center of the bottom surface of the heating chamber and the heating characteristic by the above-mentioned two excitation ports, a planar object is formed. It is possible to heat the heated product evenly.

FIG. 9 shows a fifth embodiment of the present invention. FIG. 9 shows a case where the present embodiment is applied to the annular rectangular waveguide 1 of FIG. 8, and the annular rectangular waveguide 1 is a ridge waveguide. Here, as shown in the figure, the ridge waveguide is a rectangular waveguide in which a recess 34 is provided in the central portion of the H surface of the waveguide to reduce the height of the central portion. The ridge waveguide may be concave symmetrically in the upper and lower sides of the H plane, or may be concave instead of symmetrical. When the H surface on the upper side is recessed as shown in FIG. 9, foreign matter (object to be heated such as liquid food) entering the annular rectangular waveguide 1 from the separation line 8 portion on the upper surface is the separation line portion on the lower surface. It becomes easier to flow from the bottom. The ridge waveguide has a lower cutoff frequency than a rectangular waveguide having the same external dimensions, and the waveguide wavelength λg becomes short when a microwave having the same frequency is propagated. Therefore, the size can be reduced as compared with an annular rectangular waveguide having the same electric length and formed of a rectangular waveguide.

FIG. 10 shows a sixth embodiment of the present invention.
FIG. 10 shows that this embodiment is applied to an annular rectangular waveguide whose E surface is perpendicular to the axis of the annular portion, as in the second embodiment. In this embodiment, the annular rectangular waveguide 22 has a bent portion 35 of a required width formed inside the tube along the part of the separation line in the approximate center of the H surface. The rotary plate portion 24a contacts the wall surface of the heating chamber, and the excitation port 28 is directly opened on the rotary plate portion 24a and on the E surface of the movable side annular portion 22b. Excitation mouth 28
The position of is rotatable with respect to the rotation axis, and the rotation axis has
Similar to the second embodiment, the rotation drive mechanism and the rotation angle detection mechanism are connected. In this embodiment, in addition to the operation and effect of the second embodiment, when the dimension shown by d in FIG. 10 is made smaller than the dimension shown by h, the operation becomes similar to that of the ridge waveguide, and the guide wavelength becomes shorter. It is possible to reduce the outer dimension r ₂ .

[0035]

As described above, according to the present invention,
First, at least a part of the waveguide is formed in an annular shape, and the annular portion is separated into a fixed annular portion fixed to the heating chamber side along the circumferential direction and a rotatable movable annular portion, and fixed. Since the microwave power source is connected to the annular portion and the excitation opening is connected to the movable annular portion, the excitation opening position can be freely selected by appropriately rotating the movable annular portion according to the item to be cooked. In addition, a bottom center excitation port can be realized by providing an annular waveguide on the bottom surface of the heating chamber, with the movable annular portion inside and locating the excitation port at the center of rotation through the waveguide, etc. The liquid or the like contained in the container can be locally heated with high efficiency and uniformly. Further, even when the annular waveguide is provided on the bottom surface of the heating chamber as described above, the weight sensor can be incorporated in the rotation center shaft portion.

Secondly, the waveguide is constituted by a rectangular waveguide, at least a part of the rectangular waveguide is formed in an annular shape, and the annular portion is heated at a substantially central portion of the H surface along the circumferential direction. Since the fixed annular portion fixed to the chamber side and the movable movable annular portion are separated, the microwave power source is connected to the fixed annular portion, and the excitation port is connected to the movable annular portion. The microwave radiation becomes very small, and almost all the microwaves from the microwave power supply can be emitted from the excitation port. Therefore, local heating or the like according to the cooking item can be appropriately realized.

Thirdly, the waveguide is constituted by a rectangular waveguide, and at least a part of the rectangular waveguide is formed in an annular shape and the H surface is perpendicular to the central axis of the annular shape. The annular portion is separated into a fixed annular portion fixed to the heating chamber side along the circumferential direction at a substantially central portion of the H surface and a movable annular portion which is rotatable, and a microwave power source is connected to the fixed annular portion to form a movable annular portion. Since the excitation port is connected to the portion, the annular rectangular waveguide has a flat shape, and the top plate of the annular rectangular waveguide is also used as the bottom of the heating chamber, so that it can be easily incorporated into the bottom of the heating chamber. Therefore, it is possible to easily realize a local heating structure for a liquid contained in a tall container.

Fourthly, the waveguide is constituted by a rectangular waveguide, and at least a part of the rectangular waveguide is formed in an annular shape so that the H surface is perpendicular to the central axis of the annular shape. The annular portion is separated into a fixed annular portion fixed to the heating chamber side along the circumferential direction at a substantially central portion of the H surface and a movable annular portion which is rotatable, and a microwave power source is connected to the fixed annular portion to form a movable annular portion. Since the excitation port is connected to the waveguide wall forming the E surface in the section with or without the waveguide, as described above, the upper surface plate of the annular rectangular waveguide is also used as the bottom surface of the heating chamber. As a result, it is possible to facilitate the incorporation into the bottom of the heating chamber and to easily realize a structure in which the excitation port is located near the center of rotation of the movable ring.

Fifth, the waveguide is constituted by a rectangular waveguide, and at least a part of the rectangular waveguide is formed in an annular shape so that the E plane is perpendicular to the central axis of the annular shape. The annular portion is separated into a fixed annular portion fixed to the heating chamber side along the circumferential direction at a substantially central portion of the H surface and a movable annular portion which is rotatable, and a microwave power source is connected to the fixed annular portion to form a movable annular portion. Since the excitation port is connected to the part, the outer diameter of the annular rectangular waveguide is reduced, and the rotating plate part can also be used as the heating chamber side wall surface to facilitate the incorporation into the heating chamber side part. it can.

Sixth, the waveguide is constituted by a rectangular waveguide, and at least a part of the rectangular waveguide is formed in an annular shape so that the E surface is perpendicular to the central axis of the annular shape. The annular portion is separated into a fixed annular portion fixed to the heating chamber side along the circumferential direction at a substantially central portion of the H surface and a movable annular portion which is rotatable, and a microwave power source is connected to the fixed annular portion to form a movable annular portion. Since the excitation port is connected to the H-plane waveguide wall in the section with or without the waveguide, as described above, the rotating plate of the annular rectangular waveguide also serves as the heating chamber side wall surface. Thus, the ease of incorporation into the side portion of the heating chamber can be obtained, and a structure in which the excitation port is located between the movable annular portion and its rotation center can be realized. Therefore, by rotating the movable annular portion, the position of the excitation port on the side wall of the heating chamber can be changed, and the excitation mode can be set according to the item to be cooked. It can be carried out.

Seventh, the electrical length of one round of the annular portion is approximately n · λ.
Since g / 2 (however, n is an arbitrary integer, λg is a guide wavelength), there are n places where the microwave traveling in the clockwise direction and the microwave traveling in the counterclockwise direction in the annular rectangular waveguide have the same phase. , If the excitation port is located at this place, the microwave output to the heating chamber becomes large. Therefore, by rotating the movable annular portion with the passage of time to switch the excitation port to the position of the n points, it is possible to obtain a highly efficient and uniform heating characteristic.

Eighth, the electrical length of one round of the annular portion is (n +
(1 / m)) · λg (however, n, m; any integer, λ
g; wavelength in the tube), and by providing m excitation ports,
It is possible to operate these m excitation ports complementarily so that when one microwave output is large, the other microwave output is small. Therefore, regardless of the rotation angle of the movable annular portion, the microwave can always be output to the heating chamber, uniform heating can be performed, and the operating point for the microwave power source can be prevented from changing.

Ninth, since the rectangular waveguide is a ridge waveguide, the cutoff frequency is lower than that of the rectangular waveguide having the same external dimensions, and when the microwave of the same frequency is propagated, the guide wavelength λg is shortened. You can hide it. Therefore, the annular rectangular waveguide can be miniaturized and easy assembling can be obtained.

Tenth, since a bent portion having a required width is formed in the tube along the separation portion in the center of the H-plane of the annular portion, the same effect as in the case of using the ridge waveguide can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing an annular rectangular waveguide portion in a first embodiment of a high frequency heating apparatus according to the present invention with a part cut away.

FIG. 2 is a vertical sectional view of an annular rectangular waveguide portion in the first embodiment.

FIG. 3 is a cross-sectional view showing how the annular rectangular waveguide is attached to the heating chamber in the first embodiment.

FIG. 4 is a perspective view showing an annular rectangular waveguide portion in a second embodiment of the present invention with a part cut away.

FIG. 5 is a vertical sectional view of an annular rectangular waveguide portion in the second embodiment.

FIG. 6 is a cross-sectional view showing how the annular rectangular waveguide is attached to the heating chamber in the second embodiment.

FIG. 7 is a perspective view showing an annular rectangular waveguide portion according to a third embodiment of the present invention with a part cut away.

FIG. 8 is a perspective view showing an annular rectangular waveguide portion according to a fourth embodiment of the present invention with a part cut away.

FIG. 9 is a perspective view showing an annular rectangular waveguide portion in a fifth embodiment of the present invention with a part cut away.

FIG. 10 is a perspective view showing an annular rectangular waveguide portion in a sixth embodiment of the present invention with a part cut away.

[Explanation of symbols]

 1, 22 annular rectangular waveguide 1a, 22a fixed side annular portion 1b, 22b movable side annular portion 8, 25 separation line 9, 10, 26, 27 waveguide 11, 28, 32, 33 excitation port 13 axis 15 motor Combined weight sensor 17 Heating chamber 18 Magnetron (microwave power source) 20 Container 21 Object to be heated 34 Recess in central portion of H surface provided in ridge waveguide 35 Bent portion

Claims (10)

[Claims] 1. A high-frequency heating device for propagating microwaves oscillated by a microwave power source through a waveguide and radiating the microwaves from an excitation port into a heating chamber to microwave an object to be heated housed in the heating chamber by microwaves. At least a part of the waveguide is formed in an annular shape, and the annular portion is divided into a fixed annular portion fixed to the heating chamber side along the circumferential direction and a rotatable movable annular portion, and the fixed annular portion is formed. The microwave power source is connected to, and the excitation port is connected to the movable annular portion. 2. A high-frequency heating device for propagating microwaves oscillated by a microwave power source through a waveguide and radiating the microwaves from an excitation port into a heating chamber to microwave an object to be heated housed in the heating chamber by microwaves. Fixation in which the waveguide is formed by a rectangular waveguide, at least a part of the rectangular waveguide is formed in an annular shape, and the annular portion is fixed to the heating chamber side along the circumferential direction at a substantially central portion of the H surface. Separated into an annular part and a movable annular part that is rotatable, and connecting the microwave power source to the fixed annular part,
A high-frequency heating device, characterized in that the excitation port is connected to the movable annular portion. 3. A high-frequency heating apparatus for propagating a microwave oscillated by a microwave power source through a waveguide to radiate the microwave from an excitation port to a heating chamber and microwave heating an object to be heated housed in the heating chamber. The waveguide is constituted by a rectangular waveguide, and at least a part of the rectangular waveguide is formed in an annular shape so that the H surface is perpendicular to the central axis of the annular shape. Part is divided into a fixed annular part fixed to the heating chamber side along the circumferential direction and a movable annular part which is rotatable, the microwave power source is connected to the fixed annular part, and the movable annular part is connected to the movable annular part. A high-frequency heating device comprising an excitation port connected. 4. A high-frequency heating apparatus, wherein microwaves oscillated by a microwave power source are propagated by a waveguide and are radiated from an excitation port to a heating chamber, and an object to be heated housed in the heating chamber is microwave-heated. The waveguide is constituted by a rectangular waveguide, and at least a part of the rectangular waveguide is formed in an annular shape so that the H surface is perpendicular to the central axis of the annular shape. Section is divided into a fixed annular portion fixed to the heating chamber side along the circumferential direction and a rotatable movable annular portion, and the microwave power source is connected to the fixed annular portion. A high-frequency heating device, characterized in that the exciting port is connected to a planar waveguide wall with or without a waveguide. 5. A high-frequency heating apparatus for propagating microwaves oscillated by a microwave power source through a waveguide and radiating the microwaves from an excitation port to a heating chamber to microwave an object to be heated housed in the heating chamber by microwaves. The waveguide is constituted by a rectangular waveguide, and at least a part of the rectangular waveguide is formed in an annular shape so that the E surface is perpendicular to the central axis of the annular shape, and the annular portion is substantially in the center of the H surface. Part is divided into a fixed annular part fixed to the heating chamber side along the circumferential direction and a movable annular part which is rotatable, the microwave power source is connected to the fixed annular part, and the movable annular part is connected to the movable annular part. A high-frequency heating device comprising an excitation port connected. 6. A high frequency heating apparatus for propagating microwaves oscillated by a microwave power source through a waveguide and radiating the microwaves from an excitation port to a heating chamber to microwave an object to be heated housed in the heating chamber by microwaves. The waveguide is constituted by a rectangular waveguide, and at least a part of the rectangular waveguide is formed in an annular shape so that the E surface is perpendicular to the central axis of the annular shape, and the annular portion is substantially in the center of the H surface. Part is divided into a fixed annular part fixed to the heating chamber side along the circumferential direction and a movable annular part which is rotatable, and the microwave power source is connected to the fixed annular part. A high-frequency heating device, characterized in that the exciting port is connected to a planar waveguide wall with or without a waveguide. 7. The electrical length of one round of the annular portion is approximately n · λg
/ 2 (where n is an arbitrary integer, λg is a guide wavelength), and the high-frequency heating device according to any one of claims 2 to 6. 8. The electrical length of one round of the annular portion is (n + (1
/ M)) · λg (where n and m are arbitrary integers, λg is a guide wavelength), and the number of the excitation ports is m, and the high frequency wave according to any one of claims 2 to 6. Heating device. 9. The high frequency heating apparatus according to claim 2, wherein the rectangular waveguide is a ridge waveguide. 10. The high-frequency heating device according to claim 2, wherein a bent portion having a required width is formed in the pipe along a separation portion at a substantially central portion of the H surface of the annular portion. .