JP2003332037A - High frequency dielectric heating device and refrigerating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain the miniaturization and cost reduction of a matching device. <P>SOLUTION: A ferroelectric container 23 is disposed between an earth side electrode 24 and a high-tension side electrode 27. An object 33 is disposed in the ferroelectric container 23, and an antifreezing solution 36 which is a dielectric is filled around the object 33. The antifreezing solution 36 is a secondary refrigerant of a cooler 37. An air layer between the electrodes 24, 27 and the object 33 is thereby reduced to diminish a fluctuating range of impedance load between the electrodes 24, 27. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency dielectric heating device for dielectrically heating an object such as food disposed between electrodes by applying high-frequency electromagnetic waves between a pair of electrodes facing each other, and a high frequency thereof. The present invention relates to a refrigeration system equipped with a dielectric heating device.

[0002]

2. Description of the Related Art A high frequency dielectric heating device has a frequency of 0.3 MHz.
A dielectric heating device using electromagnetic waves in the frequency band of 300 MHz, which is microwave (300 MHz to 30 GH).
z) Compared with the dielectric heating device, the wavelength is long, the internal permeability is high, and it is excellent in heating a thick object from inside and outside. For example, it is used in the food industry to thaw frozen tuna, frozen meat blocks, and the like.

FIG. 10 shows, for example, the document “Frozen Vol.
9 is a block diagram showing a conventional high-frequency decompression device shown on pages 13-18 of "No. 9" (issued in 1995). In the figure,
An object cradle 2 is provided in the heat insulation cabinet 1. An object 3 such as a food is placed on the object cradle 2.

Above the object receiving table 2 in the heat insulation box 1,
The high voltage side electrode 4 is arranged. A ground-side electrode 5 that faces the high-voltage side electrode 4 is arranged in the heat insulation box 1.
The object 3 is arranged between the high voltage side electrode 4 and the ground side electrode 5. In addition, the high voltage side electrode 4 and the ground side electrode 5
A high frequency power source 6 is connected to the. A cooler 7 that keeps the inside of the heat insulating cabinet 1 in a low temperature atmosphere is arranged in the heat insulating cabinet 1.

Next, the operation will be described. A high frequency electromagnetic wave of 13 MHz band is applied between the high voltage side electrode 4 and the ground side electrode 5 by the high frequency generating power source 6. As a result, the object 3 is dielectrically heated and thawed to near 0 ° C. At this time, since the inside of the heat insulation cabinet 1 is kept at a low temperature by the cooler 7, the object 3 is thawed in a sanitary manner.

However, in the conventional high-frequency defrosting apparatus as described above, the electrical characteristics (resistance and capacitance) between the electrodes 4 and 5
However, it is difficult to match the resonance circuit because it largely varies depending on the material, amount and temperature condition of the object 3. In particular, when the object 3 is an irregularly shaped object such as food, it is greatly affected by the air layer existing between the electrodes 4 and 5. In addition, electromagnetic waves may be concentrated on the corners of the object 3 and the defrosted state may become uneven.

On the other hand, FIG. 11 shows, for example, Japanese Patent Laid-Open No. 10-
It is a circuit diagram which shows the conventional high frequency decompression apparatus shown by 134953 gazette. A variable transformer (coil transformer for impedance conversion) 9 is connected to the high frequency power supply 6 via an input matching detection circuit 8. Variable transformer 9
Has a tap switching unit 9a. A matching coil 10 is provided between the tap switching portion 9a and the high voltage side electrode 4.
And a variable capacitor (varicon) 11 are connected in series.

According to this conventional example, the load impedance of the object 3 and the output impedance of the high frequency amplifier circuit are matched by the variable transformer 9 and the defrosting process can be performed in accordance with the change in the material and quantity of the object 3. it can.

[0009]

However, as shown in FIG.
Even in the high-frequency decompressor with the circuit configuration as shown in
Since the adjustable range of the variable transformer 9 and the variable capacitor 11 is wide, the matching device as a whole is large and expensive.

The present invention has been made to solve the above problems, and it is an object of the present invention to obtain a high frequency dielectric heating device and a refrigerating device which can downsize the matching unit and reduce the cost. To aim.

[0011]

A high frequency dielectric heating device according to the present invention is a device for dielectrically heating an object arranged between electrodes by applying a high frequency electromagnetic wave between a pair of electrodes facing each other. A dielectric is placed between the electrodes so as to reduce the air layer between the electrodes and the object.

Further, a ferroelectric container as a dielectric for accommodating an object is arranged between the electrodes. Further, the dielectric contains an antifreezing liquid as a secondary refrigerant of the cooler, and the antifreezing liquid keeps the surroundings of the object at a low temperature. Furthermore, the antifreeze liquid has a relative permittivity and a relative loss factor similar to pure water under the conditions of the frequency and the temperature of the high frequency electromagnetic wave used. The dielectric also includes a large number of ferroelectric material masses. Further, the ferroelectric substance mass has a relative dielectric constant larger than that of pure water and a relative dielectric loss ratio smaller than that of pure water under the conditions of the frequency and temperature of the high frequency electromagnetic wave used.

The refrigerating apparatus according to the present invention applies a high frequency electromagnetic wave between a pair of electrodes facing each other,
A high-frequency dielectric heating device for dielectrically heating an object arranged between electrodes, and a cooling means for cooling the object with energy larger than the energy absorbed by the object during dielectric heating and freezing the object, A dielectric is placed between the electrodes so as to reduce the air layer between the electrodes and the object.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1. 1 is a block diagram showing a high frequency dielectric heating apparatus according to Embodiment 1 of the present invention. Insulation insulation 2
The inner wall surface of 1 has an electromagnetic wave shielding shield (outer conductor) 22
Is provided. A ferroelectric container 23 as a dielectric is housed in the insulating heat-insulating box 21. The ferroelectric container 23 has a relative dielectric constant larger than that of pure water and a relative dielectric loss ratio smaller than that of pure water under the conditions of the frequency and the temperature of the high frequency electromagnetic wave to be used, such as T.
It is made of i-based ceramic. For example, MgT
The relative permittivity of iO ₂ is about 100, and the relative loss factor is about 10 ^−4.
Is.

A flat plate-shaped ground electrode 24 is arranged between the bottom surface of the insulating heat-insulating chamber 21 and the bottom surface of the ferroelectric container 23. The ground-side electrode 24 has a flat-plate ground-side conductor portion 25 and an insulating coating portion 26 formed on the surface of the ground-side conductor portion 25 on the ferroelectric container 23 side.

A flat plate-shaped high-voltage side electrode 27 is arranged on the ferroelectric container 23 in the insulating heat-insulating chamber 21. The high-voltage side electrode 27 has a flat plate-shaped high-voltage side conductor portion 28 and an insulating coating portion 29 formed on the surface of the high-voltage side conductor portion 28 on the ferroelectric container 23 side. The ground side and high voltage side electrodes 24 and 27 are arranged in parallel with each other with the ferroelectric container 23 interposed therebetween.

The earth side and high voltage side electrodes 24 and 27 are
A high frequency power supply 31 is connected via a lead wire 30. High frequency power source 31 and electrodes 2 on the ground side and the high voltage side
A matching unit 32 is connected between the terminals 4 and 27. The matching device 32 has a variable transformer and a variable capacitor.

An object 33 such as frozen food is contained in the ferroelectric container 23. The object 33 is covered with an insulating sheet 34 such as a polyethylene film. A cryoprotective substance 35 is put between the insulating sheet 34 and the object 33. When the object 33 is a fresh food, for example, glycerin or sucrose aqueous solution is used as the cryoprotective substance 35.

The ferroelectric container 23 is filled with an antifreezing liquid 36 which is a dielectric. The object 33 is immersed in the antifreeze liquid 36 while being wrapped in the insulating sheet 34. The antifreeze liquid 36 is a secondary refrigerant of the cooler 37, and the periphery of the object 33 is kept at a low temperature by the antifreeze liquid 36. The cooler 37 is connected to the ferroelectric container 23 via a supply pipe 38 and a discharge pipe 39. As a result, the antifreeze liquid 36 is circulated between the ferroelectric container 23 and the cooler 37.

FIG. 2 is an enlarged view of the main part of FIG. The high voltage side electrode 27 is provided with a gas vent hole 27a. When the antifreeze liquid 36 is poured into the ferroelectric container 23, the air layer remaining in the ferroelectric container 23 is removed from the gas vent hole 27a.

Next, the operation will be described. Matching device 32
The variable transformer (L component) and the variable capacitance capacitor (C component) are adjusted to resonate the circuit, and a high frequency electromagnetic wave is applied between the electrodes 24 and 27. Thereby, the electrodes 24, 2
The object 33 arranged between 7 is dielectrically heated, and the object 33 such as frozen food is thawed. At this time, by circulating the antifreeze liquid 36 between the ferroelectric container 23 and the cooler 37, the surroundings of the object 33 are kept at a low temperature, and the object 3
3 is thawed hygienically.

In such a high frequency induction heating device, the air layer between the electrodes 24 and 27 should be reduced as much as possible.
Since the ferroelectric container 23 and the antifreezing liquid 36, which are dielectrics, are arranged between the electrodes 24 and 27, the adjustment range of the variable transformer and the variable capacitor of the matching device 32 can be reduced. That is, the variation range of the impedance load between the electrodes 24 and 27 is reduced, and the matching device 32 can be downsized and the cost can be reduced.

Further, the electromagnetic waves are less likely to concentrate on the corners of the object 33, and the object 33 can be heated more uniformly.

As the material of the antifreeze liquid 36, one having a large dielectric constant and a small dielectric loss ratio is desirable. For example,
If it is a 40% aqueous ethanol solution, the freezing point is about -30 ° C.
The relative dielectric loss factor is about 0.28, and it has a dielectric characteristic similar to that of pure water under the conditions of the frequency and the temperature of the high frequency electromagnetic wave used, which is preferable. Others, antifreeze 36
The dielectric properties of the aqueous solution that can be used as the above are shown in FIGS.

FIG. 3 is an explanatory view showing the dielectric characteristics of PEG (polyethylene glycol) which is the first example of the antifreeze liquid 36 of FIG. 1, and FIG. 4 is the dielectric characteristics of glycerin which is the second example of the antifreeze liquid 36 of FIG. 5 is an explanatory view showing the antifreezing liquid 36 of FIG.
3 is an explanatory diagram showing the dielectric characteristics of diethylene glycol, which is the third example, and FIG. 6 is an explanatory diagram showing the dielectric characteristics of ethanol, which is the fourth example of the antifreeze liquid 36 in FIG.

Embodiment 2. Next, FIG. 7 is a configuration diagram showing a main part of a high-frequency dielectric heating device according to a second embodiment of the present invention. Around the target object 33 in the ferroelectric container 23, a large number of ferroelectric substance masses 41 are put together with the antifreeze liquid 36. The ferroelectric substance mass 41 is a pellet-shaped, spherical, or chip-shaped small mass made of a ferroelectric substance. The ferroelectric substance mass 41 is made of a material under the same conditions as the ferroelectric container 23, for example, a Ti-based ceramic. Other configurations are similar to those of the first embodiment.

In such a high-frequency dielectric heating device, a large number of ferroelectric substance masses 41 are distributed between the ferroelectric container 23 and the object 23, and the antifreeze liquid 36 is further poured thereinto to create an atmosphere around the object 33. Allow the temperature to cool. In the first embodiment, only the air layer between the electrodes 24 and 27 is eliminated, but the ferroelectric substance mass 41 is distributed between the electrodes 24 and 27, so that the capacitance between the electrodes 24 and 27 is increased. Can be controlled by the characteristics of the ferroelectric substance block 41, so that the electrodes 24, 2
The impedance characteristic between 7 can be maintained more stably.

Embodiment 3. Next, FIG. 8 is a configuration diagram showing a main part of a high frequency dielectric heating device according to a third embodiment of the present invention. In the figure, the ferroelectric container 23 is provided with, for example, a slit-shaped cold air inlet 42 and a cold air outlet 43. A cold air supply device 44 is connected to the cold air inlet 42. In the first and second embodiments, the antifreeze liquid 36 is supplied into the ferroelectric container 23, but in the third embodiment, the cool air is circulated between the cold air supply device 44 and the ferroelectric container 23, and the target object is cooled. The ambient temperature around 33 is kept low. Other configurations are similar to those of the second embodiment.

Even with such a high-frequency dielectric heating device, the ferroelectric substance mass 41 is distributed between the electrodes 24 and 27, so that the electrostatic capacitance between the electrodes 24 and 27 is changed according to the characteristics of the ferroelectric substance mass 41. Since it can be controlled, the electrodes 24, 2
The impedance characteristic between 7 can be maintained more stably.

Fourth Embodiment Next, FIG. 9 is a configuration diagram showing a main part of a high-frequency dielectric heating device according to a fourth embodiment of the present invention. On the upper part of the ferroelectric container 23, a container upper lid 45
Is provided. Inside the container 23, a flexible high voltage side electrode 46 is provided. Between the high voltage side electrode 46 and the ground side electrode 24, the object 33 and the ferroelectric substance mass 41 wrapped in the insulating sheet 34 are arranged. The configuration of the flexible electrode is, for example, in Japanese Utility Model Laid-Open No. 56-1292.
No. 93 publication. Other configurations are the same as those in the third embodiment.
Is the same as.

Even with such a high-frequency dielectric heating device, the ferroelectric substance mass 41 is distributed between the electrodes 24 and 46, so that the electrostatic capacitance between the electrodes 24 and 46 is changed according to the characteristics of the ferroelectric substance mass 41. Since it can be controlled, the electrodes 24, 4
The impedance characteristic between 6 can be maintained more stably. Further, when the target object 33 is an irregular shape such as food, the high-voltage side electrode 46 is deformed in accordance with the outer shape of the target object 33, so that the influence of the air layer between the electrodes 24 and 46 can be reduced. Therefore, the electromagnetic wave distribution applied to the object 33 can be made uniform.

Fifth Embodiment Next, a refrigerating apparatus according to Embodiment 5 of the present invention will be described. The refrigerating apparatus of the fifth embodiment freezes the target object 33 by the cooling means (cooler 37, cold air supply apparatus 44) in the first to fourth embodiments. That is, at the time of dielectric heating, the target object 33 is cooled by the energy larger than the energy absorbed by the target object 33, and the target object 33 is frozen. Such a freezing method is disclosed in, for example, Japanese Patent Laid-Open No. 2001-245645.

In such a refrigeration system, the high voltage side electrode 27
Alternatively, by reducing the air layer between 46 and the ground-side electrode 24, the adjustment range of the variable transformer and the variable capacitor of the matching unit 32 can be reduced, and the matching unit 32
Can be downsized and the cost can be reduced.

[0034]

As described above, in the high frequency dielectric heating device and the refrigerating device of the present invention, the dielectric is arranged between the electrodes so as to reduce the air layer between the electrodes and the object. The variation range of the impedance load between them becomes small, and the matching device can be downsized and the cost can be reduced.

Further, since the ferroelectric container for accommodating the object is arranged between the electrodes, it is possible to downsize the matching box and reduce the cost. Furthermore, the dielectric contains an antifreezing liquid as a secondary refrigerant of the cooler, and the antifreezing liquid keeps the surroundings of the object at a low temperature. Therefore, the matching device can be downsized and the cost can be reduced. Furthermore, since the antifreeze liquid has the same relative permittivity and relative loss factor as pure water under the frequency and temperature conditions of the high frequency electromagnetic wave used, the impedance characteristics between the electrodes should be kept more stable. You can
In addition, since the dielectric contains a large number of ferroelectric substance blocks, the matching device can be downsized and the cost can be reduced. further,
The ferroelectric substance mass has a relative dielectric constant larger than that of pure water and a relative dielectric loss ratio smaller than that of pure water under the conditions of the frequency and the temperature of the high-frequency electromagnetic wave used.
The impedance characteristic between the electrodes can be maintained more stably.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a high-frequency dielectric heating device according to a first embodiment of the present invention.

FIG. 2 is an enlarged configuration diagram showing a main part of FIG.

FIG. 3 is an explanatory diagram showing a dielectric characteristic of PEG which is a first example of the antifreeze liquid of FIG.

FIG. 4 is an explanatory diagram showing a dielectric characteristic of glycerin which is a second example of the antifreeze liquid of FIG.

5 is an explanatory diagram showing a dielectric characteristic of diethylene glycol which is a third example of the antifreeze liquid of FIG. 1. FIG.

FIG. 6 is an explanatory diagram showing the dielectric characteristics of ethanol, which is the fourth example of the antifreeze liquid of FIG.

FIG. 7 is a configuration diagram showing a main part of a high-frequency dielectric heating device according to a second embodiment of the present invention.

FIG. 8 is a configuration diagram showing a main part of a high-frequency dielectric heating device according to a third embodiment of the present invention.

FIG. 9 is a configuration diagram showing a main part of a high frequency dielectric heating device according to a fourth embodiment of the present invention.

FIG. 10 is a configuration diagram showing an example of a conventional high-frequency decompression device.

FIG. 11 is a circuit diagram showing a conventional high-frequency decompression device.

[Explanation of symbols]

23 ferroelectric container (dielectric), 24 earth side electrode,
27,46 High-voltage side electrode, 36 Antifreeze (dielectric), 3
7 Cooler (cooling means), 41 Ferroelectric substance mass (dielectric), 44 Cold air supply device (cooling means).

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3K090 AA01 AB03 BA04 BB01 EB21                 4B022 LA06 LB01 LF09 LF16 LN01                       LQ08 LT02

Claims (7)

[Claims] 1. A high-frequency dielectric heating device for inductively heating an object placed between said electrodes by applying a high-frequency electromagnetic wave between a pair of electrodes facing each other. So as to reduce the air layer,
A high frequency dielectric heating device, wherein a dielectric is arranged between the electrodes. 2. The high frequency dielectric heating device according to claim 1, wherein a ferroelectric container serving as the dielectric that accommodates the object is disposed between the electrodes. 3. The dielectric according to claim 1, wherein the dielectric contains an antifreezing liquid as a secondary refrigerant of a cooler, and the surroundings of the object are kept at a low temperature by the antifreezing liquid. High frequency induction heating device. 4. The antifreezing liquid has a relative permittivity and a relative loss factor similar to pure water under the conditions of frequency and temperature of the high frequency electromagnetic wave used. High frequency induction heating device. 5. The high frequency dielectric heating device according to claim 1, wherein the dielectric includes a large number of ferroelectric substance blocks. 6. The ferroelectric substance mass has a relative permittivity larger than pure water and a relative dielectric loss factor smaller than pure water under the frequency and temperature conditions of the high frequency electromagnetic wave used. The high-frequency dielectric heating device according to claim 5, wherein: 7. A high-frequency dielectric heating device for dielectrically heating an object arranged between the electrodes by applying a high-frequency electromagnetic wave between a pair of electrodes facing each other, and absorbing the object during the dielectric heating. Cooling means for cooling the object with an energy larger than the energy to be applied, and freezing the object, and a dielectric material between the electrodes so as to reduce an air layer between the electrode and the object. A refrigerating apparatus, characterized in that.