JPH07282971A - High frequency heating device - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a high-frequency heating apparatus, and an object thereof is to efficiently heat the food 5 to make the heating distribution uniform. [Structure] The electromagnetic wave from the magnetron 1 is introduced into the heating chamber 3 by the waveguide 2 through the openings 6 and 7 to heat the food 5, and the openings 6 and 7 are opened by the operation of the opening shield 8. -By shielding, the feeding point is moved apparently to move the electric field to improve the efficiency and uniformity of heating.

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 device for heating an object to be heated, such as food, for supplying electric power (how to put electromagnetic waves into a heating chamber), and particularly to make the heating distribution uniform and improve the heating efficiency. It is related to the configuration.

[0002]

2. Description of the Related Art A microwave oven, which is a typical high-frequency heating device, has conventionally been constructed as shown in FIGS.

The microwave oven shown in FIG. 24 has a general structure using a turntable. Here, the electromagnetic wave emitted from the magnetron 1 as the electromagnetic wave radiating section is transmitted through the waveguide 2 and distributed in the heating chamber 3 as a standing wave determined by the shape of the heating chamber 3 and the position of the opening 52. The food 5 generates heat according to the electric field component of the standing wave and the dielectric loss of the food 5. The electric power P [W / m ³ ] absorbed per unit volume of food depends on the strength E [V / m] of the applied electric field, the frequency f [Hz], and the relative permittivity ε _r and dielectric loss tangent tan δ of the food. (Equation 1)
Expressed as Since the heating distribution of the food 5 is determined by the standing wave distribution of electromagnetic waves, in order to suppress the unevenness of the heating distribution, the turntable 15 of the stand on which the food is placed is rotated to make the heating distribution on a concentric circle uniform. .

[0004]

[Equation 1]

Further, as another means for uniformization, the heating chamber 3
There was also a stirrer method in which a radio wave is agitated by a metal plate in the inside, and a rotating waveguide method in which the metal part of the exit itself of the waveguide 2 is largely rotated, but the turntable type is the most commercialized. Has been done.

FIG. 25 shows a type in which two openings 53 and 54 are provided on the side surface of the heating chamber 3, but the heating distribution is not so different from that of the microwave oven shown in FIG.

In FIG. 26, in order to increase the heating efficiency, the metal piece 55 is moved in the waveguide 2 by the motor 56, and the matching state (the state where there are few reflections and the electromagnetic waves are well present in the food) is switched according to the food. It is a thing.

FIG. 27 is a plan view of the sushi 47 on the plate 4, which is a typical flat food product, as viewed from above. When this is heated in the microwave oven of FIG. 24, the characteristics of FIG. 28 are obtained. The horizontal axis of FIG. 28 is the standing time after the end of heating, and the vertical axis is the temperature. The average temperature of the four bruises in the central portion 48 (the portion with diagonal lines) of the suimai 47 is d, and the average temperature of the twelve bruises in the peripheral portion 49 (the portion without the slash) of the suimai 47 is e, and the surrounding portion is It is shown that 49 is hotter than the central portion 48. This is a characteristic of a conventional microwave oven in which a flat food product such as sushi is heated only at the edges and is hard to be heated in the center.

[0009]

However, in the above-mentioned conventional structure, when the electromagnetic wave is introduced into the heating chamber by connecting the waveguide and the heating chamber, the position of the connecting portion (opening) must be selected at an appropriate position. However, there was a problem that the target electric field distribution was not obtained and the heating distribution could not be estimated at all.

Especially in many turntable types, the feeding point (where electromagnetic waves enter the heating chamber, generally the above-mentioned opening) is fixed on the top or side surface,
Once the configuration is decided, it seems that the standing wave distribution in the heating chamber is always constant, but in reality, the standing wave distribution tends to be disturbed as it moves away from the feeding point, such as the degree of electromagnetic wave absorption depending on the shape of the food and the dielectric constant. Become. When the standing wave distribution is disturbed, the heating distribution does not become more and more desired, and in most microwave ovens, the edges of the food become hot and the central part (especially the bottom) does not easily get hot. In this case, no matter how much the turntable is rotated, the distribution in the radial direction and the distribution in the vertical direction seen from the center of rotation are not improved. Therefore, the central solution (especially the bottom) of the food is strongly heated as a fundamental solution. Unless it is forcibly made, the finished state will be extremely unsatisfactory for the user.

On the other hand, when the feeding point is located at the center of the bottom surface, conversely, the electric field passes through the food placed on it, so that the central portion of the bottom surface tends to be hot and the edge does not easily get hot. Furthermore, it is difficult to configure a stirring means such as a turntable because the feeding point on the bottom surface is an obstacle.

In addition to the above-mentioned problems, in addition to the above-mentioned problems, the electromagnetic waves that are forcibly moved extremely, such as the stirring of the electromagnetic waves by the stirrer and the movement of the feeding point by the rotating waveguide,
There was a problem that standing waves did not easily rise in the heating chamber and the matching condition between the heating chamber and the magnetron deteriorated, resulting in reduced efficiency.
If the efficiency is lowered, the heating time becomes long, the waiting time of the user becomes long, the power is wasted, and the thermal stress of the magnetron increases, so that the reliability is deteriorated.

The present invention is intended to solve the above-mentioned problems. A high-frequency wave having a high heating efficiency is provided by setting an aimed electric field distribution to make the heating distribution of the object to be heated uniform and efficiently supplying electromagnetic waves into the heating chamber. The purpose is to realize a heating device.

[0014]

In order to achieve the above object, the high frequency heating apparatus of the present invention has the following constitution.

That is, a heating chamber for loading and unloading an object to be heated, an electromagnetic wave radiating part for radiating an electromagnetic wave, a waveguide for guiding the electromagnetic wave radiated from the electromagnetic wave radiating part into the heating chamber, the heating chamber and the guiding part. It has a plurality of openings that connect to a wave tube and a control unit that controls the emission of electromagnetic waves from the electromagnetic wave emission unit, and one of the openings is the central portion of the heating chamber bottom surface ( The first opening is formed in the vertical center and the horizontal center.

Further, a heating chamber having a rectangular bottom surface for loading and unloading an object to be heated, an electromagnetic wave radiating section for radiating electromagnetic waves, a waveguide for guiding electromagnetic waves radiated from the electromagnetic wave radiating section into the heating chamber, and the electromagnetic waves And a control unit for controlling the emission of electromagnetic waves from the radiation unit, the heating chamber bottom and the waveguide are connected by a rectangular opening, all sides of the heating chamber bottom is any of the openings. It is configured to be parallel to the side of.

Further, a heating chamber for loading and unloading the object to be heated,
An electromagnetic wave emitting portion that emits an electromagnetic wave; a waveguide that guides the electromagnetic wave emitted from the electromagnetic wave emitting portion into the heating chamber; a plurality of openings that connect the heating chamber and the waveguide; It is configured to have an opening shield portion that shields at least one of the openings, a drive portion that drives the opening shield portion, and a control portion that controls emission of electromagnetic waves from the electromagnetic wave emission portion and the drive portion.

A heating chamber for loading and unloading the object to be heated,
An electromagnetic wave radiating unit that radiates an electromagnetic wave, a waveguide that guides the electromagnetic wave radiated from the electromagnetic wave radiating unit into the heating chamber, a control unit that controls the emission of the electromagnetic wave from the electromagnetic wave radiating unit, the heating chamber and the It has a plurality of openings for connecting to the waveguide, and has a configuration in which matching is achieved (rated output is obtained) when other openings except one arbitrary opening are shielded.

A heating chamber for loading and unloading an object to be heated,
An electromagnetic wave emitting portion that emits an electromagnetic wave, a waveguide that guides the electromagnetic wave emitted from the electromagnetic wave emitting portion into the heating chamber, an opening that connects the heating chamber and the waveguide, and a bottom surface of the heating chamber. An opening shielding portion that shields the opening by rotating around a rotation axis at a position other than the central portion (vertical center and horizontal center), and a drive that rotationally drives the opening shielding portion around the rotation axis. And a control unit that controls the emission of electromagnetic waves from the electromagnetic wave emission unit and the drive unit.

A heating chamber for loading and unloading the object to be heated,
An electromagnetic wave emission part that emits an electromagnetic wave, a waveguide that guides the electromagnetic wave emitted from the electromagnetic wave emission part into the heating chamber, an opening that connects the heating chamber and the waveguide, and the opening is constant. The configuration includes an opening blocking section that blocks by a rotational motion at a speed, a driving section that rotationally drives the opening blocking section, and a control section that controls radiation of electromagnetic waves from the electromagnetic radiation section and the driving section.

A heating chamber for loading and unloading the object to be heated,
An electromagnetic wave emission part that emits an electromagnetic wave, a waveguide that guides the electromagnetic wave emitted from the electromagnetic wave emission part into the heating chamber, an opening connecting the heating chamber and the waveguide, and a shield for the opening. The disk-shaped opening shield, the drive unit that drives the opening shield, and the control unit that controls the emission of electromagnetic waves from the electromagnetic wave emission unit and the drive unit.

Also, a heating chamber for loading and unloading the object to be heated,
An electromagnetic wave emitting portion that emits an electromagnetic wave, a waveguide that guides the electromagnetic wave emitted from the electromagnetic wave emitting portion into the heating chamber, an opening that connects the heating chamber and the waveguide, and an electromagnetic wave transmitting resin or the like. Section and an electromagnetic wave blocking section such as a metal for blocking the opening, a driving section for driving the opening blocking section, and a control section for controlling the radiation of electromagnetic waves from the electromagnetic wave radiating section and the driving section. And a configuration having.

Also, a heating chamber for loading and unloading the object to be heated,
An electromagnetic wave emission part that emits an electromagnetic wave, a waveguide that guides the electromagnetic wave emitted from the electromagnetic wave emission part into the heating chamber, a plurality of openings that connect the heating chamber and the waveguide, and the electromagnetic wave emission. And a control unit for controlling the emission of electromagnetic waves from the section, and the opening area of the opening located closest to the center of the bottom of the object to be heated is minimized.

Further, a heating chamber for loading and unloading the object to be heated,
An electromagnetic wave radiating unit that radiates an electromagnetic wave, a waveguide that guides the electromagnetic wave radiated from the electromagnetic wave radiating unit into the heating chamber, a control unit that controls the emission of the electromagnetic wave from the electromagnetic wave radiating unit, the heating chamber and the It has multiple openings that connect to the waveguide and does not match when other openings are shielded except for the opening closest to the bottom center of the object to be heated (the rated output is not output. Not configured).

Further, a heating chamber for loading and unloading an object to be heated, an electromagnetic wave radiating part for radiating an electromagnetic wave, a waveguide for guiding the electromagnetic wave radiated from the electromagnetic wave radiating part into the heating chamber, the heating chamber and the guiding part. An opening that connects the wave tube, an opening shield that shields the opening while moving at a non-constant speed, a drive unit that drives the opening shield, and radiation of electromagnetic waves from the electromagnetic radiation unit and the It has a configuration including a control unit that controls the drive unit.

[0026]

The present invention has the following functions due to the above construction.

That is, since the heating chamber and the waveguide are connected by a plurality of openings, and the first opening is provided at the center of the bottom of the heating chamber (vertical center and horizontal center), It is possible to heat the central portion of the bottom surface of the food with one opening and heat the edge of the food with the other opening.

Further, since the rectangular heating chamber bottom and the waveguide are connected by the rectangular opening, and all sides of the heating chamber bottom are parallel to any of the openings, electromagnetic wave radiation is achieved. A strong electric field in the opposite direction is generated by the electromagnetic wave radiated from the part so that it sandwiches the opening, and the electric field distribution aimed at when the heating chamber is considered as a cavity resonator is set on the bottom of the heating chamber. It occurs as a standing wave distribution.

Further, since at least one of the plurality of openings is shielded by the opening shield, it is possible to switch the standing wave distribution generated for each unshielded opening or to mix various standing waves. You can

Further, since there is provided a plurality of openings and a configuration is adopted in which matching is achieved (rated output is output) when other openings except one arbitrary opening are shielded, power is supplied from any opening. Even in the case of being heated, the object to be heated can be efficiently heated.

Further, since the opening shielding portion shields the opening portion by rotating around the rotation axis at a position other than the central portion (vertical center and horizontal center) of the bottom surface of the heating chamber, the opening portion is covered with the bottom surface of the heating chamber. It can be provided in various places including the central part of the.

Further, since the opening shielding portion shields the opening portion by the rotational movement at a constant speed, it can be realized by a driving portion such as a motor which rotates at a constant speed.

Further, since the opening is shielded by the disc-shaped opening shield, a corner-free opening shield can be realized.

Further, since the opening shielding portion is composed of an electromagnetic wave transmitting portion such as a resin and an electromagnetic wave shielding portion such as a metal, when the position is changed by the driving portion, the electromagnetic wave transmitting and shielding states can be changed.

Regarding the opening areas of the plurality of openings,
Since the opening area of the opening located closest to the center of the bottom of the object to be heated is minimized, the electromagnetic waves emitted from the minimum opening can be made smaller than the electromagnetic waves emitted from other openings.

Further, since the configuration is such that no matching is achieved (no rated output is produced) when the other openings except the one located closest to the bottom center of the object to be heated are shielded, the electromagnetic waves emitted at this time Can be less than the electromagnetic waves emitted from other openings.

Further, since the opening shielding portion shields the opening portion while moving at a non-constant speed, the time required for the opening operation / shielding operation and the opening time / shielding time are changed for each opening portion. be able to.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of the high frequency heating apparatus of the present invention. In FIG. 1, the electromagnetic wave emitted from the magnetron 1 as the electromagnetic wave radiating section heats the food 5 on the plate 4 placed in the heating chamber 3 via the waveguide 2. The openings 6 and 7 that connect the waveguide 2 and the heating chamber 3 and guide the electromagnetic waves are configured such that the first opening 6 is located at the center of the heating chamber 3 and the second opening 7 is located near the magnetron 1. The weak electric field (node) of the electromagnetic wave propagating in the waveguide 2 and the weak electric field (node) of the electromagnetic wave distributed as a standing wave in the heating chamber 2 are connected. (This will be described in detail later with reference to FIG. 10.) On the other hand, in order to improve the heating efficiency and the heating distribution of the food 5, there is an opening shielding portion 8 so as to cover the openings 6 and 7, and its structure is a disc shape. Then, it has an electromagnetic wave transmitting portion 9 made of a low loss material which hardly absorbs an electromagnetic wave and an electromagnetic wave shielding portion 10 made of a metal, and is rotated by a rotating shaft 11 made of a low loss material which hardly absorbs an electromagnetic wave. The rotating shaft 11 is provided at a position between the openings 6 and 7 with the heating chamber 3 and the waveguide 2.
Is rotatably driven by being connected to a motor 12 which is a driving unit. In accordance with this rotation, the apparent opening position through which electromagnetic waves enter the heating chamber 3 from the waveguide 2 changes (the first opening 6 and the second opening 7 are switched), and the electric field distribution is changed. Is changing. (This will be described later in detail with reference to FIGS. 5 and 6.) At the same time, the rotary shaft 11 is also connected to the first gear 13, and the rotation of the first gear 13 transmits the rotational force to the second gear 14. . The second gear 14 is connected to the turntable 15 and is intended to make the food 5 uniform in the direction of the concentric circles viewed from the center of rotation by rotating the food 5. By making the number different from the number (in the case of this embodiment, the number of teeth of the second gear 14 is increased), further homogenization is achieved. In addition, the shape recognition sensor 16 is the food 5
Recognizes the shape of the
Controls the operation of the magnetron 1, the motor 12, the cooling fan 18 for cooling the magnetron, etc. according to the signal. In this case, the optimal power feeding method (switching pattern of the openings 6 and 7, the electromagnetic radiation pattern of the magnetron 1, etc.) is set in advance according to the shape of the food,
It is switched by a signal from the shape recognition sensor 16. Further, for safety, the bottom cover 19 is used to open the opening 8.
The turntable 15 is held by the support portion 20.

FIG. 2 is a sectional view taken along the line AA 'of FIG. The center of the first opening 6 is located at the center (vertical center and horizontal center) on the bottom surface of the heating chamber 3, and the second opening 7 is located closer to the magnetron 1 than that. Each of the openings 6 and 7 has a rectangular shape, and the bottom surface of the heating chamber 3 having the same rectangular shape is parallel to the four sides.

FIG. 3 is a sectional view taken along line BB 'of FIG. The opening shielding portion 8 covers the openings 6 and 7, and has the semicircular electromagnetic wave shielding portion 10 on the circular electromagnetic wave transmitting portion 9.
It is rotated by the rotating shaft 11. In the case of FIG. 3, because of the electromagnetic wave blocking portion 10, it is difficult for the electromagnetic wave in the waveguide 2 to enter the heating chamber 3 through the first opening 6 and easily enter through the second opening 7. There is. On the other hand, when the rotating shaft 11 rotates half a turn, on the contrary, electromagnetic waves in the waveguide 2 easily enter the heating chamber 3 through the first opening 6 and hardly enter through the second opening 7. Therefore, the openings 6 and 7 are apparently switched by the rotation of the opening shield 8.

In this embodiment, one rotation shaft 11 rotates both the opening shield 8 and the turntable 15. Of course, it is also possible to provide the rotating shafts separately and aim for further homogenization. In addition, the opening shield 8
Although it is configured to rotate in the heating chamber 3, it may be configured to linearly move left and right in the waveguide 2. As for the motor 12, a simple AC motor is used to rotate the motor at a constant speed, but a stepping motor may be used to control the motor 12 to achieve even uniformity. Although the second opening 7 is formed on the bottom surface of the heating chamber 3, it may be formed on another wall surface of the heating chamber 3. Further, although the control is performed based on the signal of the shape recognition sensor 16, the detection unit may be configured by other sensing means.

4 to 9 are configuration diagrams showing the results of simulating the relationship between the electric field inside the high-frequency heating device and the dielectric loss of food.

FIG. 4 is a perspective view of a high frequency heating apparatus according to an embodiment of the present invention. It is assumed that electromagnetic waves are excited from a feeding point 21 (although the magnetron 1 is not shown) with the same configuration as that of FIG.

FIGS. 5 and 6 are perspective views cut by CC ′ to simulate the electric field distribution of the high-frequency heating apparatus of FIG. 4 (when there is no food), and show the electric field generated in the resonance state with equal electric field strength. It is indicated by a line. (It can be considered that the electric field is stronger (belly) at a place where the annual ring-shaped pattern is more complicated.) This indicates a difference in electric field distribution depending on the position of the opening.

FIG. 5 shows the case where only the first opening 6 is opened, and the antinode of the electric field is 4 in the x direction in the heating chamber 3.
First, there are three antinodes of the electric field in the y direction and one antinode of the electric field in the z direction.

FIG. 6 shows the case where only the second opening 7 is opened, and the antinode of the electric field is 5 in the x direction in the heating chamber 3.
One, one antinode of the electric field is generated in the y direction, and one antinode of the electric field is generated in the z direction.

FIG. 7 is a perspective view of a flat-shaped food product 22 (such as a sweet potato) heated in the high-frequency heating device of FIG.

FIGS. 8 and 9 simulate the distribution of the dielectric loss when the food of FIG. 7 is placed on the first opening 6 of the high frequency heating apparatus of FIG.
It is a perspective view cut by D '. It is considered that there is a loss in the shaded area and the temperature rises.

FIG. 8 shows the case where only the first opening 6 is open, showing that the central bottom 23 of the food product 22 is heated.

FIG. 9 shows the case where only the second opening 7 is open, showing that the end 24 of the food product 22 is heated.

The reason why the electric field distributions shown in FIGS. 5 and 6 and the loss distributions shown in FIGS. 8 and 9 are obtained will be described.

First, the propagation of electromagnetic waves in the waveguide 2 will be described. 10 to 12 are cross-sectional structural views of the main part of the high-frequency heating apparatus according to the embodiment. The dimensions and the like are the same as those in FIGS. 1 and 4, and in FIG. And only the first opening 6 is shown. The distance Lt between the feeding point 21 of the magnetron 1 and the center 25 of the opening 6 is an odd number of λg / 4, where λg is the wavelength of the electromagnetic wave transmitted in the waveguide 2 to the left. Double the distance. This is because when an electromagnetic wave is transmitted through the waveguide 2, it travels to the left in FIG. 2 while repeating the strength and weakness based on the guide wavelength λg determined by the shape of the waveguide 2, and λg /
This is because the electric field always becomes weak at a position of an odd multiple of 4 (in the transmission in the waveguide, the magnetic field and the electric field have the same phase, and the magnetic field also becomes weak). Here, Lt = λg / 4 ×
9 is set. The solid arrow indicates the direction of the strong electric field, and the direction of the electric field (and magnetic field) is opposite for each λg / 2. Therefore, the direction of the arrow is reversed for each λg / 2 away from the feeding point 21. However, each is 2.45GHz
It repeats inversion at the frequency of. In FIG. 10, since the electric field (and magnetic field) is weakly connected to the opening 6 of the heating chamber 3, electromagnetic waves can efficiently enter the heating chamber 3 without disturbing the electric field in the waveguide 2.

Here, the guide wavelength λg propagating in the waveguide 2
4 and FIG. 10, the depth of the waveguide 2 is a, the thickness is b, the number of peaks of the radio wave in the depth direction is m, and the peak of the electromagnetic wave in the thickness direction is If the number is n and the wavelength of the electromagnetic wave in vacuum is λ≈122 mm, then (Equation 2) is obtained. Generally, m = 1 and n = 0 are often adopted, and in this case, (Equation 3) is obtained. As specific values, a = 80 mm, b = 4
If it is 0 mm, then λg is approximately 188 mm. (However, all dimensions are internal dimensions that do not include the plate thickness.)

[0055]

[Equation 2]

[0056]

[Equation 3]

Next, resonance of electromagnetic waves in the heating chamber 3 at this time will be described. In the case of FIG. 10, electromagnetic waves in the heating chamber 3 tend to cause a resonance state, but strong electric fields 26 and 27 (solid arrows) in opposite directions that sandwich the opening 6 are generated, and the openings in the heating chamber 3 are generated. At 6, the electric field becomes stable in a resonance state in which the electric field becomes weak (a node). At this time, the most efficient heating chamber 3
Electromagnetic waves will enter inside. (However, in the resonance state,
Unlike the transmission state as in the waveguide 2, the electric field and the magnetic field are out of phase by 90 °. ) The resonance state is determined by the shape of the heating chamber and the position of the opening. In the case of FIG. 11 (and FIG. 5) showing the electric field distribution in the heating chamber 3 at this time, four in the x direction of the heating chamber and in the y direction. Three, one strong electric field is generated in the z direction. This is the antinode of the electric field caused by the electromagnetic waves being distributed as standing waves in the heating chamber due to the resonance state, and the number of antinodes is called a mode. Usually, when the shape of the heating chamber 3 is three-dimensionally expressed and the dimensions in each direction are x, y, and z, if the antinodes of the electric field are m, n, and p in each direction, the mode is (mnp). There is. In the present embodiment, the center position of the first opening 6 is aligned with the center position of the depth x and the width y of the bottom surface of the heating chamber 3, and at the same time, a strong electric field is generated so as to sandwich the opening 6. Since it is configured so that it becomes a node at the opening 6, even mode (m; even) can easily occur in the depth x direction, and the width y
In the direction, an odd mode (n; odd number) is likely to occur, and at the same time, another mode is difficult to occur. It is easy to see that FIG. 6 is the mode (511) as well as FIG. 5 is the mode (431).

For reference, there is no food in the heating chamber 3,
When the heating chamber 3 is a rectangular parallelepiped, the heating chamber 3 can be considered as a cavity resonator, and a mode in which the heating chamber 3 can stand can be obtained depending on the size of the heating chamber 3 and the position of the opening. The dimensions of the heating chamber 3 are x, y, and z, and the number of modes standing in each direction is a combination of m, n, and p that satisfies (Equation 4). (X, y, z
Is in mm, m, n, p are integers)

[0059]

[Equation 4]

On the other hand, when there is food, the deviation from (Equation 4) occurs due to the influence of wavelength compression due to the dielectric constant of food.
However, it has been experimentally found that even if there is food, a mode that satisfies (Equation 4) is about to stand near the opening and that the mode is often disturbed at a position away from the opening. . Therefore, when λ ≈ 122 mm, the mode (43
As an example for establishing 1), it is possible to select x = 330 mm, y = 300 mm, z = 215 mm, etc., which are dimensions that substantially satisfy (Equation 4).

FIG. 12 shows a flat (short) food 22 near the center of the heating chamber 3 (that is, above the first opening 6).
FIG. 6 is a diagram showing how the electric field is bent when the is placed. The food 22 pushes and bends a pair of opposite strong electric fields 26 and 27 generated so as to sandwich the opening 6, and a strong electric field 28 in the food is generated. It is heated based on the electric power P shown in 1). At this time, a heat generating portion 29 is generated in the lower center of the food product 22, and the inside of the food product 22 is heated without the edges being boiled. This is the distribution of losses shown in FIG. However, at this time, since the lower central part of the food 22 is too hot and the edge is cold, a problem opposite to the conventional microwave oven occurs.
Therefore, it is aimed at uniformization by switching to the second opening 7 as described above. Experience shows that unless the opening is at the center of the bottom surface of the heating chamber 3 (just below the food) (as is the case in FIG. 9), the edge of the food 22 is always hot. This is because the food 22 itself is used by the heating chamber 3 at openings other than the center of the bottom surface.
The cause may be that the electric field distribution inside is disturbed, and the electric field occurs only in a direction away from the opening so as to cover the edge of the food. The center of the bottom of the heating chamber 3 (just below the food)
In the case of the opening 6 as well, the electric field distribution is disturbed as the distance from the opening 6 increases, but a stable strong electric field 26, 2 is generated near the opening 6.
Since 7 is maintained, the inside of the food 22 is heated without boiling the edges. (In FIG. 12, the electric field different from that in FIG. 11 is shown only as the strong electric field deforming portion 30, but in extreme cases, the four strong electric fields 31 on the top surface of the heating chamber 3 may become three or two. Since food is generally placed in the center of the heating chamber 3, the first opening 6 must be placed in the center of the bottom of the heating chamber 3, but the second opening 7 has a degree of freedom in the mounting position. It is becoming known that there is.

As described above, according to the first embodiment, it is understood that the heating of the first, third, fifth, sixth, seventh and eighth inventions can be made uniform.

13 to 16 are sectional views of the heating chamber 3.
How the standing of the electric field changes depending on the position of the opening on the wall will be described.

In order to set the mode according to (Equation 4) using the heating chamber 3 as a cavity resonator, it is preferable to determine the position of the opening as shown in FIGS. (However, for simplification, it is assumed here to be two-dimensional.) In FIG. 13, strong electric fields 33 and 34 in opposite directions are generated so as to sandwich the opening 32, and the mode (22 *) is set. It is easily conceivable that the modes of (even number, even number, *) can be similarly set up in this way.

In FIG. 14, strong electric fields 36 and 37 in opposite directions are generated so as to sandwich the opening 35, and the (23 *) mode is set. It is easily conceivable that the modes of (even number, odd number, *) (odd number, even number, *) are similarly set up.

In FIG. 15, strong electric fields 39 and 40 in opposite directions are generated so as to sandwich the opening 38, and the (33 *) mode is set. It is easily conceivable that the modes of (odd number, odd number, *) can be similarly set up.

However, in FIG. 16, an attempt is made to generate strong electric fields 42 and 43 in opposite directions so as to sandwich the opening 41.
The mode does not follow the equation (4), and the electric field distribution cannot be estimated. This is because the wall surface of the heating chamber 3 and the opening 41 are not parallel.

As described above, according to the second aspect of the present invention, by making the wall surface of the heating chamber 3 and the openings 6 and 7 parallel to each other, as shown in FIG.
It can be seen that an intended electric field can be generated as shown in FIGS. 6, 13, 14 and 15.

FIG. 17 is a characteristic diagram showing the heating efficiency of one embodiment of the fourth invention. FIG. 17 is a Smith chart showing a reflection state (matching state) viewed from the magnetron 1, and a hatched portion is a high efficiency region 44 (a region where electromagnetic waves enter the heating chamber 3 most efficiently). At this time, when only the first opening 6 and the second opening 7 are opened, the reflection characteristics are set to 45 and 46, and both are in the high efficiency region 44 and are matched so that the rated output is obtained. ing. Therefore, as shown in FIG. 18, the heating efficiency can be improved at the same time as the uniform heating as shown in FIG. 18, when the 16 claws 47 of FIG. 27 are heated by the high frequency heating apparatus of the first embodiment of the present invention. It is a characteristic view which shows temperature variation. Taking the standing time from the end of heating as the abscissa and the temperature as the ordinate, the average temperature d of 4 in the central portion 48 of the sword 47 and the average temperature e of 12 in the peripheral portion 49 of the sill 47 are shown. , The temperature is almost the same, which indicates that uniform heating has progressed from FIG.

However, it cannot be said that the alignment as shown in FIG. The first opening 6,
There is no doubt that the second openings 7 tend to heat the central portion 48 and the peripheral portion 49, respectively, but the temperature does not always rise at exactly the same speed. For example, as shown in FIG. 19, the average temperature d of the central portion 48 is the average temperature e of the peripheral portion 49.
Larger things (reversed from FIG. 28 of the conventional characteristic) may occur. Because the number of springs is 12 in the surrounding area 49.
On the other hand, there are only four central portions 48, and even if the same amount of electromagnetic waves enter the heating chamber 3 through the openings 6 and 7, the central portion 48 may heat up faster. is there. Therefore, as a solution for changing the balance between the rise of the central temperature and the ambient temperature, one embodiment of the ninth and tenth inventions and another embodiment of the third invention are shown in FIGS.

In FIG. 20, unlike the configuration of FIG. 2, by making the opening area of the first opening 6 smaller than the opening area of the second opening 7, heating from the first opening 6 is performed. An example in which the amount of electromagnetic waves entering the chamber 3 is narrowed is shown. As a result, by suppressing the rise of the central temperature, the characteristics shown in FIG. 19 can be optimized to the characteristics shown in FIG.

FIG. 21 shows an example in which the reflection state (matching state) at the first opening 6 is shifted, unlike the characteristics shown in FIG. The characteristic 46 in the first opening 6 is shifted as shown in FIG. 21 while the characteristic 46 in the second opening 7 is kept in the high efficiency region. Similar to the effect of FIG. 20, the electromagnetic waves entering the heating chamber 3 through the first opening 6 are reduced (the reflection is increased) to suppress the rise of the central temperature, so that the characteristics shown in FIG. It can be optimized to the characteristics.

22 and 23 show an example in which the ratio of the opening time of the openings 6 and 7 is changed. FIG. 23 shows ff ′ of FIG.
FIG. 22 is different from the configuration of FIG. 2 in that the electromagnetic wave blocking unit 10 has a blocking protrusion 50 and a blocking opening 51. In this case, the second opening 7 is opened for most of the time during which the opening shield 8 rotates once,
The blocking protrusion 50 is on the second opening 7 and the blocking opening 51
The first opening 6 is opened only when is on the first opening 6. As a result, the characteristic shown in FIG. 19 can be optimized to the characteristic shown in FIG. 18 by suppressing the increase in the central temperature and promoting the increase in the ambient temperature.

Although not shown, as an embodiment of the eleventh invention, a stepping motor is used as the motor 12, and the rotation of the opening shield 8 is not constant, so that the openings 6 and 7 are not rotated.
It is conceivable to shorten the time in the middle of switching between the shielding and the opening. For example, as shown in FIG. 17, even if the characteristics 45 and 46 of only one of the openings 6 and 7 can be realized, the reflection occurs in the middle of switching (for example, when the openings 6 and 7 are half open). Is more likely to decrease efficiency. Therefore, the opening shield 8 can be operated at a high speed only at that timing, and the heating efficiency can be kept as low as possible.

In this embodiment, the flat food is taken as an example to describe the improvement of the heating efficiency and the uniform heating distribution. However, there are various types and shapes of foods, and in addition, the influence of dishes must be considered. Therefore, as an example other than this embodiment, it should be added that various methods can be considered for optimization, such as changing the balance of the opening times of the openings 6 and 7 depending on the food.

[0076]

As described above, the high frequency heating apparatus of the present invention has the following effects.

(1) The heating chamber and the waveguide are connected by a plurality of openings, and the central portion of the bottom of the heating chamber (vertical center and horizontal center)
Since the first opening is used to heat the bottom central portion of the object to be heated with the first opening, the edges of the object to be heated are heated with the other openings, so that the entire surface is uniform. Can be heated to.

(2) Since all sides of the bottom surface of the rectangular heating chamber are parallel to any of the sides of the rectangular opening, the opening may be sandwiched by the electromagnetic waves emitted from the electromagnetic wave radiation section. A strong electric field in the opposite direction is generated, and an aimed electric field distribution is generated as a standing wave distribution on the bottom surface of the heating chamber, which is the same as that calculated when the heating chamber is considered as a cavity resonator. Therefore, the mode in the heating chamber can be set to the desired mode (at least in the vicinity of the opening), and the object to be heated can have the desired heating distribution.

(3) Since at least one of the plurality of openings is shielded by the opening shield, it is possible to switch the standing wave distribution generated for each unshielded opening or to mix various standing waves. Therefore, the heating distribution of the object to be heated can be switched or combined to be uniform.

(4) Since the configuration has a plurality of openings (matching output is obtained) when other openings except one arbitrary opening are shielded, the power is supplied from any opening. Even in the case of being heated, the object to be heated can be efficiently heated. Therefore, the heating time is short, and the waiting time for the user is shortened. Similarly, there is an effect that power saving can be achieved. Further, similarly, the thermal stress of the radio wave radiation part is reduced and the reliability is increased.

(5) Since the opening shielding portion shields the opening portion by rotating about the rotation axis at a position other than the central portion (vertical center and horizontal center) of the bottom of the heating chamber, the electric field distribution in the heating chamber Can be stirred to make the heating distribution of the object to be heated uniform. Similarly, since the opening can be provided in the central portion of the bottom surface of the heating chamber, it is possible to switch between heating and not heating the central portion of the bottom surface of the object to be heated with a simple structure, so that the heating is performed more uniformly. be able to.

(6) Since the opening shielding portion shields the opening portion by the rotational movement at a constant speed, it can be realized by the driving portion rotating at a constant speed. Therefore, it is possible to stir the electric field distribution in the heating chamber with a simple structure (a structure that is inexpensive and easy to make) to make the heating distribution of the object to be heated uniform.

(7) Since the aperture is shielded by the disc-shaped aperture shield, a corner-free aperture shield can be realized. Therefore, there is an effect that the electric field distribution in the heating chamber can be agitated with a simple configuration (an inexpensive and easy-to-make configuration) to make the heating distribution of the object to be heated uniform. Further, similarly, since it is an opening shield without corners, there is little risk of damage due to contact with other components, and safety can be improved.

(8) Since the opening shielding portion is composed of an electromagnetic wave transmitting portion such as a resin and an electromagnetic wave shielding portion such as a metal, when the position of the opening shielding portion is changed by the driving portion, the electromagnetic wave transmitting and shielding states can be changed. Therefore, the standing wave distribution in the heating chamber can be switched, various standing waves can be mixed, and the electric field distribution can be agitated, so that the heating distribution of the object to be heated can be made uniform. Similarly, the electromagnetic wave transmitting portion can prevent sparks between the opening and the electromagnetic wave shielding portion, and enhance safety.

(9) Regarding the opening area of the plurality of openings,
Since the opening area of the opening located closest to the center of the bottom surface of the object to be heated is minimized, the electromagnetic waves emitted from the minimum opening can be made smaller than the electromagnetic waves emitted from other openings. Therefore, with the same opening area, the effect on the distribution is too large compared to other openings.The effect on the distribution of the openings that are closest to the bottom of the heating chamber and the object to be heated is suppressed, and the effect on the distribution of other openings is affected. The heating distribution of the object to be heated can be made more uniform by increasing the temperature.

(10) Since the configuration is such that no matching is obtained (rated output is not output) when the other openings except the one closest to the center of the bottom surface of the object to be heated are shielded, it appears at this time. The electromagnetic waves can be made smaller than the electromagnetic waves emitted from other openings. Therefore, in the same alignment state, the influence on the distribution is too large compared to other openings, and the influence on the distribution of the opening closest to the center of the bottom surface of the heated object is suppressed, and the influence on the distribution of other openings is suppressed. The heating distribution of the object to be heated can be made more uniform by increasing the temperature.

(11) Since the opening shielding portion shields the opening portion while moving at a non-constant speed, the time required for the opening operation / shielding operation and the opening time / shielding time are different for each opening portion. Can be changed. Therefore, the electromagnetic wave does not enter the heating chamber stably and the standing wave distribution is hard to stand. It is possible to efficiently heat the object to be heated by prolonging the time when the distribution is open. Therefore, the heating time is short, and the waiting time for the user is shortened. Similarly, there is an effect that power saving can be achieved. Further, similarly, there is an effect that the thermal stress of the radio wave radiation part is reduced and the reliability is increased.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of a high-frequency heating device according to an embodiment of the present invention.

FIG. 2 is a sectional configuration diagram of the high-frequency heating device.

FIG. 3 is a cross-sectional configuration diagram of the high-frequency heating device.

FIG. 4 is a perspective configuration diagram of the high-frequency heating device.

FIG. 5 is a perspective sectional configuration diagram of the high-frequency heating device.

FIG. 6 is a perspective sectional configuration diagram of the high-frequency heating device.

FIG. 7 is a perspective configuration diagram of food.

FIG. 8 is a perspective sectional configuration diagram of the food.

FIG. 9 is a perspective sectional configuration diagram of the food.

FIG. 10 is a sectional configuration diagram of the high-frequency heating device.

FIG. 11 is a sectional configuration diagram of the high-frequency heating device.

FIG. 12 is a sectional configuration diagram of the high-frequency heating device.

FIG. 13 is a sectional configuration diagram of a high-frequency heating device according to another embodiment.

FIG. 14 is a sectional configuration diagram of a high-frequency heating device according to another embodiment.

FIG. 15 is a sectional configuration diagram of a high-frequency heating device according to another embodiment.

FIG. 16 is a sectional configuration diagram of a high-frequency heating device according to another embodiment.

FIG. 17 is a characteristic diagram of a high frequency heating device according to an embodiment of the present invention.

FIG. 18 is a characteristic diagram of a high-frequency heating device according to an embodiment of the first invention.

FIG. 19 is a characteristic diagram of the high-frequency heating device.

FIG. 20 is a sectional configuration diagram of a high-frequency heating device according to an embodiment of the present ninth invention.

FIG. 21 is a characteristic diagram of the high-frequency heating device according to the tenth embodiment of the invention.

FIG. 22 is a sectional configuration diagram of a high-frequency heating device according to another embodiment of the third invention.

FIG. 23 is a sectional configuration diagram of the high-frequency heating device.

FIG. 24 is a sectional configuration diagram of a conventional high-frequency heating device.

FIG. 25 is a sectional configuration diagram of another conventional high-frequency heating device.

FIG. 26 is a sectional configuration diagram of another conventional high-frequency heating device.

FIG. 27: Schematic diagram of the shimemai on the plate

FIG. 28 is a characteristic diagram of a conventional high-frequency heating device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 magnetron (electromagnetic wave radiating part) 2 waveguide 3 heating chamber 5 food (object to be heated) 6 first opening 7 second opening 8 opening blocking part 9 electromagnetic wave transmitting part 10 electromagnetic wave blocking part 11 rotating shaft 12 motor (Drive unit) 16 Shape recognition sensor (Detection unit) 17 Control unit

Claims (14)

[Claims] 1. A heating chamber for loading and unloading an object to be heated, an electromagnetic wave radiating section for radiating electromagnetic waves, a waveguide for guiding the electromagnetic waves radiated from the electromagnetic wave radiating section into the heating chamber, the heating chamber and the guiding section. It has a plurality of openings for connecting a wave tube and a control section for controlling the emission of electromagnetic waves from the electromagnetic wave emission section, and one of the openings is provided at the center of the heating chamber bottom surface. The high-frequency heating device with the configuration provided. 2. A heating chamber having a rectangular bottom surface for loading and unloading an object to be heated, an electromagnetic wave radiating section for radiating an electromagnetic wave, a waveguide for guiding the electromagnetic wave radiated from the electromagnetic wave radiating section into the heating chamber, and the electromagnetic wave. And a control unit for controlling the emission of electromagnetic waves from the radiating unit, the heating chamber bottom and the waveguide are connected by a rectangular opening, all sides of the heating chamber bottom is any of the openings. High-frequency heating device configured parallel to the sides of the. 3. A heating chamber for loading and unloading an object to be heated, an electromagnetic wave radiating section for radiating an electromagnetic wave, a waveguide for guiding the electromagnetic wave radiated from the electromagnetic wave radiating section into the heating chamber, the heating chamber and the conductive section. A plurality of openings that connect the wave tube, an opening shield that shields at least one of the plurality of openings, a drive unit that drives the opening shield, and the emission of electromagnetic waves from the electromagnetic radiation unit. A high-frequency heating device having a configuration including a control unit that controls the drive unit. 4. The high-frequency heating device according to claim 3, wherein the shielding time of the opening shield differs depending on the opening. 5. A heating chamber for loading and unloading an object to be heated, an electromagnetic wave radiating section for radiating electromagnetic waves, a waveguide for guiding electromagnetic waves radiated from the electromagnetic wave radiating section into the heating chamber, and an electromagnetic wave radiating section for guiding the electromagnetic waves. A control unit that controls the emission of electromagnetic waves, and has a plurality of openings that connect the heating chamber and the waveguide,
A high-frequency heating device configured to match when other openings are shielded except one arbitrary opening. 6. A heating chamber for loading and unloading an object to be heated, an electromagnetic wave radiating part for radiating an electromagnetic wave, a waveguide for guiding the electromagnetic wave radiated from the electromagnetic wave radiating part into the heating chamber, the heating chamber and the guiding part. An opening for connecting the wave tube, an opening blocking portion for blocking the opening by rotating around a rotation axis at a position other than the central portion of the heating chamber bottom surface, and the opening blocking portion for rotating the rotation axis. A high-frequency heating apparatus having a configuration including a drive unit that is rotationally driven in the center, and a control unit that controls emission of electromagnetic waves from the electromagnetic wave emission unit and the drive unit. 7. A heating chamber for loading and unloading an object to be heated, an electromagnetic wave radiating section for radiating an electromagnetic wave, a waveguide for guiding the electromagnetic wave radiated from the electromagnetic wave radiating section into the heating chamber, the heating chamber and the conductive section. An opening that connects the wave tube, an opening shield that shields the opening with a rotational movement at a constant speed, a drive unit that rotationally drives the opening shield, and radiation of electromagnetic waves from the electromagnetic radiation unit and the A high-frequency heating device configured to include a control unit that controls a drive unit. 8. A heating chamber for loading and unloading an object to be heated, an electromagnetic wave radiating section for radiating an electromagnetic wave, a waveguide for guiding the electromagnetic wave radiated from the electromagnetic wave radiating section into the heating chamber, the heating chamber and the conductive section. An opening for connecting a wave tube, a disc-shaped opening blocking portion for blocking the opening, a driving portion for driving the opening blocking portion, radiation of electromagnetic waves from the electromagnetic radiation portion, and the driving portion. A high-frequency heating device having a control unit for controlling. 9. A heating chamber for loading and unloading an object to be heated, an electromagnetic wave radiating section for radiating electromagnetic waves, a waveguide for guiding the electromagnetic waves radiated from the electromagnetic wave radiating section into the heating chamber, the heating chamber and the guiding section. An opening that connects the wave tube, an electromagnetic wave transmitting portion such as a resin and an electromagnetic wave shielding portion such as a metal that shields the opening portion, a driving portion that drives the opening shielding portion, and the electromagnetic wave radiation A high-frequency heating device having a configuration that includes radiation of electromagnetic waves from a unit and a control unit that controls the drive unit. 10. The high frequency heating device according to claim 9, wherein the electromagnetic wave transmitting portion is provided between the wall surface of the heating chamber and the electromagnetic wave shielding portion. 11. A heating chamber for loading and unloading an object to be heated, an electromagnetic wave radiating section for radiating electromagnetic waves, a waveguide for guiding the electromagnetic waves radiated from the electromagnetic wave radiating section into the heating chamber, the heating chamber and the conductive section. A plurality of openings connecting the wave tube, and a control unit for controlling the emission of electromagnetic waves from the electromagnetic wave emission unit, the opening area of the opening located closest to the bottom center of the object to be heated. A high-frequency heating device with a minimum configuration. 12. A heating chamber for loading and unloading an object to be heated, an electromagnetic wave radiating section for radiating electromagnetic waves, a waveguide for guiding electromagnetic waves radiated from the electromagnetic wave radiating section into the heating chamber, and an electromagnetic wave radiating section for guiding the electromagnetic waves. A control unit that controls the emission of electromagnetic waves, and a plurality of openings that connect the heating chamber and the waveguide, and other openings except the opening located closest to the center of the bottom of the object to be heated. A high-frequency heating device with a structure that does not match when the parts are shielded. 13. A heating chamber for loading and unloading an object to be heated, an electromagnetic wave radiating section for radiating an electromagnetic wave, a waveguide for guiding the electromagnetic wave radiated from the electromagnetic wave radiating section into the heating chamber, the heating chamber and the guiding section. An opening that connects the wave tube, and an opening shield that shields the opening while moving at a non-constant speed,
A high-frequency heating device having a configuration that includes a drive unit that drives the opening shield unit, and a control unit that controls emission of electromagnetic waves from the electromagnetic wave emission unit and the drive unit. 14. A structure having a detection unit for detecting the physical quantity of the object to be heated or the state of the inside of the heating chamber, and driving the opening shielding unit according to the output of the detection unit.
The high-frequency heating device according to any one of 6, 7, 8, 9, 10, and 13.