refrigerator

Abstract

To suppress the leakage of an alternating electric field from the heating space of a refrigerator for dielectrically heating a food product to outside.SOLUTION: A refrigerator has: a shield case 44 in which an opening 44c is provided to the front side and which is fabricated from a metal material; a flat first electrode 48 disposed within the shield case 44; a flat second electrode 50 disposed within the shield case 44 so as to face the first electrode 48 with spacing therebetween, the second electrode 50 forming a heating space HZ for dielectrically heating a food product located between the first and second electrodes 48 and 50, and being connected to ground; and an oscillation part for generating an AC voltage to be applied between the first and second electrodes 48 and 50. The facing-direction distance D between the first and second electrodes 48 and 50, the output electric power W of the oscillation part, the output impedance Z of the oscillation part, and the distance D1 from the front end 50a of the second electrode 50 to the opening 44c in the shield case 44 satisfy the given formula.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a refrigerator capable of dielectrically heating food. [Background technology]

[0002] For example, Patent Document 1 discloses a freezer capable of thawing frozen food. The freezer in Patent Document 1 has a high-frequency heating chamber that stores food to be thawed and heats the stored food by high-frequency heating (dielectric heating). The high-frequency heating chamber is configured to be able to introduce cold air from the freezer chamber. As a result, when not being used for thawing, the high-frequency heating chamber is used as a freezer chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-147919 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when dielectrically heating food as in Patent Document 1, it is necessary to prevent the alternating electric field used for the dielectric heating from leaking to the outside.

[0005] Therefore, an object of the present invention is to suppress leakage of an alternating electric field from the heating space of a refrigerator that dielectrically heats food to the outside. [Means for solving the problem]

[0006] According to one aspect of the present invention, a shield case made of a metal material and having an opening at the front that connects the inside and the outside; a first electrode having a flat plate shape and disposed within the shield case; a flat-plate-shaped second electrode that is disposed in the shield case so as to face the first electrode with a gap therebetween, that forms a heating space between the first electrode and the second electrode for dielectrically heating food, and that is connected to ground; an oscillator that generates an AC voltage to be applied between the first electrode and the second electrode, The distance D between the first electrode and the second electrode in the opposing direction, the output power W of the oscillator, the output impedance Z of the oscillator, and the distance D1 from the front end of the second electrode to the opening of the shielding case are

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[0007] According to the present invention, leakage of an alternating electric field from the heating space of a refrigerator that dielectrically heats food to the outside can be suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a vertical cross-sectional view of a refrigerator according to an embodiment of the present invention; [Figure 2] Block diagram showing the refrigerator control system [Figure 3] Perspective view of the heating module [Figure 4] Cross section of the heating module [Figure 5] Cross-sectional view of the heating module taken along line AA in Figure 4. [Figure 6] Block diagram showing the control system of the heating module [Figure 7A] A diagram showing the simulation results of the forward and backward spread of an alternating electric field. [Figure 7B] A diagram showing the simulation results of the horizontal spread of an alternating electric field. [Figure 8] FIG. 10 is a vertical cross-sectional view of a portion of a refrigerator according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] A refrigerator according to one aspect of the present invention includes a shielding case made of a metal material and having an opening at the front side that connects the inside to the outside, a flat-plate first electrode disposed within the shielding case, a flat-plate second electrode disposed within the shielding case so as to face the first electrode at a distance, forming a heating space between the first electrode and the flat-plate second electrode that dielectrically heats food and is connected to ground, and an oscillator unit that generates an AC voltage to be applied between the first electrode and the second electrode, wherein the distance D between the first electrode and the second electrode in the facing direction, the output power W of the oscillator unit, the output impedance Z of the oscillator unit, and the distance D1 from the front end of the second electrode to the opening of the shielding case are

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[0010] According to this aspect, leakage of the alternating electric field from the heating space of the refrigerator that dielectrically heats food to the outside can be suppressed.

[0011] For example, the front end of the first electrode may be farther away from the opening of the shielding case than the front end of the second electrode, thereby further suppressing leakage of the alternating electric field to the outside.

[0012] For example, the opposing direction distance D, the output power W, the impedance Z, and the distance D2 from the side end of the second electrode to the inner wall surface of the shielding case are

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[0013] For example, the side edge of the first electrode may be farther from the inner wall surface of the shielding case than the side edge of the second electrode, thereby preventing capacitance from being formed between the side edge of the first electrode and the inner wall surface of the shielding case, thereby improving the efficiency of dielectric heating of food.

[0014] For example, the heating space may be at least a part of a freezing compartment in which food is frozen, thereby allowing frozen food to be thawed directly.

[0015] Hereinafter, a refrigerator according to an embodiment of the present invention will be described with reference to the drawings.

[0016] FIG. 1 is a vertical cross-sectional view of a refrigerator according to the first embodiment. In FIG. 1, the left side is the front side of the refrigerator, and the right side is the rear side of the refrigerator. FIG. 2 is a block diagram showing a control system of the refrigerator. Note that the XYZ Cartesian coordinate system shown in the drawings is intended to facilitate understanding of the embodiments according to the present invention, and does not limit the embodiments. The X-axis direction indicates the front-to-rear direction (depth direction) of refrigerator 10, the Y-axis direction indicates the left-to-right direction (width direction), and the Z-axis direction indicates the up-and-down direction (height direction).

[0017] 1, refrigerator 10 includes a main body 12. Main body 12 is made up of an outer housing 14 made of a metal material and constituting the outer surface of refrigerator 10, an inner housing 16 made of a resin material such as ABS and constituting the inner surface of refrigerator 10, and a heat insulating material 18 such as rigid urethane foam that fills the space between outer housing 14 and inner housing 16.

[0018] The main body 12 of the refrigerator 10 has a plurality of storage compartments for storing food (ingredients, processed ingredients, etc.). In the present embodiment, the storage compartments are, from the top, a refrigerator compartment 12a, a freezer / thawing compartment 12b, a freezer compartment 12c, and a vegetable compartment 12d. In the present embodiment, the freezer / thawing compartment 12b and the freezer compartment 12c are connected to each other.

[0019] Refrigerating compartment 12a is a space maintained at a temperature range where food will not freeze, for example, a temperature range of 1°C to 5°C. Freezing / thawing compartment 12b and freezing compartment 12c are spaces maintained at a temperature range where food will freeze, for example, a temperature range of -22°C to -15°C. Freezing / thawing compartment 12b, as will be described in detail later, can not only freeze food but also heat food, for example, it can thaw frozen food. Vegetable compartment 12d is a space maintained at a temperature range equal to or higher than that of refrigerating compartment 12a, for example, a temperature range of 2°C to 7°C. In addition to these spaces, refrigerator 10 may also be provided with semi-freezing spaces at -1°C or -3°C.

[0020] In this embodiment, a machine room 12e is provided in an upper part of the main body 12 of the refrigerator 10. The machine room 8 contains a compressor 20 and other components that constitute the refrigeration cycle of the refrigerator 10 and circulate the refrigerant in the refrigeration cycle. Alternatively, the machine room 12e can be provided in a lower part of the main body 12 of the refrigerator 10.

[0021] In the present embodiment, cooling compartment 12f is provided behind freezer compartment 12c and vegetable compartment 12d. Cooler 22, through which a refrigerant passes, is disposed within cooling compartment 12f and constitutes the refrigeration cycle of refrigerator 10. Cooling compartment 12f is also provided with cooling fan 24, which blows the air (cold air) from cooling compartment 12f cooled by cooler 22 toward refrigerator compartment 12a, freezer / thawing compartment 12b, freezer compartment 12c, and vegetable compartment 12d.

[0022] In this embodiment, refrigerator 10 is provided with three doors 12g to 12i. Door 12g is openable and closable, and connects or separates refrigeration compartment 12a from the outside. Door 12h is openable and closable, and connects or separates freezing / thawing compartment 12b and freezing compartment 12c from the outside. Door 12i is openable and closable, and connects or separates vegetable compartment 12d from the outside.

[0023] Furthermore, as shown in Fig. 2, dampers 26A to 26C that control the flow rate of cool air flowing into each of the compartments 12a to 12d are arranged in the flow path between each of the compartments 12a to 12d and the cooling fan 24 (only damper 26B is shown in Fig. 1). Damper 26B is arranged in the flow path between freezing / thawing compartment 12b and cooling fan 24. The cool air passes through freezing / thawing compartment 12b and flows into freezing compartment 12c.

[0024] Furthermore, as shown in FIG. 2, refrigerator 10 is provided with temperature sensors 28A to 28C that measure the internal temperatures of refrigeration compartment 12a, freezing / thawing compartment 12b, freezing compartment 12c, and vegetable compartment 12d, respectively.

[0025] As shown in Fig. 2, the control unit 30 of the refrigerator 10 performs cooling control based on the measurement results of the multiple temperature sensors 28A-28C. That is, the control unit 30 controls the output of the compressor 20, the rotation speed of the cooling fan 24, and the opening and closing of the dampers 26A-26C, thereby maintaining appropriate temperatures in the refrigerator compartment 12a, the freezer / thawing compartment 12b, the freezer compartment 12c, and the vegetable compartment 12d. The control unit 30 is, for example, a control board disposed in the machine compartment 12e and equipped with a processor such as a CPU, a storage device such as a memory for storing programs, and circuits. The processor controls the compressor 20, the cooling fan 24, and the dampers 26A-26C according to the programs stored in the storage device.

[0026] As shown in FIG. 1, the refrigerator 10 also includes door sensors 32A-32C that detect the open / closed states of the doors 12g-12i, respectively. The door sensors 32A-32C are, for example, switches that detect the closed states of the doors 12g-12i by coming into contact with the doors. The door sensors 32A-32C are provided on the main body 12 of the refrigerator 10 at positions that allow them to come into contact with the inner surfaces of the doors 12g-12i. Detection signals from the door sensors 32A-32C are transmitted to the control unit 30. The control unit 30 controls the ON / OFF of lighting devices (not shown) provided in the refrigerator compartment 12a, freezer / thawing compartment 12b, freezer compartment 12c, and vegetable compartment 12d, for example, based on the detection signals from the door sensors 32A-32C. The switches may be mechanical switches or magnetic sensors such as Hall sensors, i.e., contactless switches. Magnetic sensors such as Hall sensors, MR sensors, and reed switches have the advantage that they can be made smaller than mechanical switches and do not impair the design of refrigerator 10 because they have no protrusions.

[0027] As shown in Fig. 2, in this embodiment, refrigerator 10 is provided with a user interface 34 that enables a user to operate refrigerator 10. User interface 34 may be a touch panel or the like built into refrigerator 10 and / or may be a mobile terminal of the user. When user interface 34 is a mobile terminal, software (application) for operating refrigerator 10 is installed on the mobile terminal.

[0028] For example, when one of the door opening / closing sensors 32A-32C detects that the corresponding door 12g-12i has been open for a predetermined period of time, the user interface 34 notifies the user that the door is open. The user interface 34 is also used by the user when thawing food in the freezing / thawing compartment 12b. The following describes the details of this freezing / thawing compartment 12b.

[0029] Fig. 3 is a perspective view of the heating module, Fig. 4 is a cross-sectional view of the heating module, Fig. 5 is a cross-sectional view of the heating module taken along line AA shown in Fig. 4, and Fig. 6 is a block diagram showing a control system of the heating module.

[0030] In the present embodiment, heating module 40 shown in Figures 3 to 5 is a module for heating frozen food, and is incorporated into refrigerator 10. Freezing / thawing compartment 12b is provided within heating module 40. As will be described in detail below, heating module 40 is configured to generate an alternating electric field within freezing / thawing compartment 12b and dielectrically heat food using the alternating electric field.

[0031] 3 to 5, the heating module 40 has a rectangular parallelepiped shape and is a double-walled structure including an inner case 42 and a shield case 44 that houses the inner case 42. The shield case 44 functions as a housing for the heating module 40. The inner case 42 defines a storage chamber in which food is stored, i.e., the freezing / thawing chamber 12b.

[0032] The inner case 42 is made of an insulating material such as resin and is a rectangular parallelepiped box with an opening on the front side that connects the inside and outside. The shield case 44 is made of a metal material, such as aluminum. The shield case 44 is also a rectangular parallelepiped box with an opening on the front side that connects the inside and outside, and houses the inner case 42 inside.

[0033] In this embodiment, as shown in Fig. 3, heating module 40 includes a drawer 46 that is inserted into and removed from freezing / thawing compartment 12b in the front-to-rear direction (X-axis direction) and that contains food. Drawer 46 is made of a resin material. Also, as shown in Fig. 5, guide rails 47 that guide drawer 46 in the front-to-rear direction (X-axis direction) when it is inserted or removed are provided on inner wall surface 42a of inner case 42. Drawer 46 like this makes it easy to insert or remove food from freezing / thawing compartment 12b.

[0034] Furthermore, the inner case 42 and shield case 44 of the heating module 40 are provided with a plurality of vent holes 42b, 44a that communicate with the freezing / thawing compartment 12b so that the food in the freezing / thawing compartment 12b can be frozen. The cool air that has passed through the damper 26B flows into the freezing / thawing compartment 12b through these vent holes 42b, 44a. This allows the food in the heating module 40, i.e., the freezing / thawing compartment 12b, to be frozen.

[0035] To dielectrically heat food within the freeze / thaw compartment 12b, for example to thaw frozen food, the heating module 40 comprises a first electrode 48 and a second electrode 50.

[0036] As shown in Figures 4 and 5, the first electrode 48 and the second electrode 50 are flat plate-shaped members made of a metal material. The first electrode 48 and the second electrode 50 are arranged in the shielding case 44 so as to face each other with a gap between them. In this embodiment, the first electrode 48 and the second electrode 50 face each other in the vertical direction (Z-axis direction) and are parallel to each other. The first electrode 48 and the second electrode 50, which face each other with a gap between them, form a heating space HZ therebetween for dielectric heating food. A drawer 46 is provided in the heating module 40 so as to be retractable into the heating space HZ between the first electrode 48 and the second electrode 50.

[0037] In the present embodiment, the first electrode 48 is disposed between the top plate portion 42c of the inner case 42 and the top plate portion 44b of the shield case 44. A space (i.e., an air layer) is provided between the shield case 44 and the first electrode 48.

[0038] In the present embodiment, the second electrode 50 is disposed on the bottom plate portion 42d of the inner case 42.

[0039] To form the heating space HZ between the first electrode 48 and the second electrode 50, as shown in FIG. 6 , the refrigerator 10 includes an oscillator 52 that generates an AC voltage to be applied between the first electrode 48 and the second electrode 50. The oscillator 52 is, for example, an oscillator circuit board disposed in the machine compartment 12e of the refrigerator 10, and is electrically connected to the first electrode 48 and the second electrode 50. The oscillator 52 converts an AC voltage from a power supply 54 of the refrigerator 10 that is connected to a commercial power source, and applies the converted AC voltage between the first electrode 48 and the second electrode 50. An AC voltage of a predetermined VHF frequency, for example, 40.68 MHz, is applied between the first electrode 48 and the second electrode 50.

[0040] When oscillator 52 applies an AC voltage between first electrode 48 and second electrode 50, an alternating electric field is generated within shield case 44 (freezing / heating compartment 12b). This alternating electric field dielectrically heats the food to be heated, which is contained in drawer 46 and placed between first electrode 48 and second electrode 50, i.e., the food placed in heating space HZ. As a result, the food is dielectrically heated.

[0041] In this embodiment, as shown in Fig. 6, the refrigerator 10 includes a matching circuit 56 that matches the impedance between the first electrode 48 and the second electrode 50. The matching circuit 56 is, for example, a circuit board housed in the heating module 40. The matching circuit 56 is electrically connected to the first electrode 48 and the second electrode 50. In this embodiment, the second electrode 50 is connected to ground.

[0042] The role of the matching circuit 56 will now be explained. As frozen food thaws, the number of water molecules in the food increases. As the number of water molecules increases, the impedance between the first electrode 48 and the second electrode 50 changes from an appropriate value, and the reflectance increases. The reflectance is the ratio of the reflected wave returning to the oscillator 52 to the incident wave output from the oscillator 52. As the reflectance increases, the efficiency of dielectric heating of the food decreases. The matching circuit 56 is provided to maintain the impedance between the first electrode 48 and the second electrode 50 at an appropriate value.

[0043] Specifically, as shown in Fig. 6, refrigerator 10 includes reflected wave detection circuit 58 so that matching circuit 56 maintains the impedance between first electrode 48 and second electrode 50 at an appropriate value. Reflected wave detection circuit 58 is provided, for example, on a board disposed in machine compartment 12e of refrigerator 10. Control unit 30 calculates a reflectance based on the incident wave output from oscillator 52 and the reflected wave detected by reflected wave detection circuit 58. Based on the calculated reflectance, control unit 30 controls matching circuit 56 so that the impedance between first electrode 48 and second electrode 50 becomes an appropriate value.

[0044] When a user places food to be heated in the heating space HZ of freezing / thawing compartment 12b and issues a heating instruction to user interface 34, control unit 30 outputs a heating start signal to oscillator 52 to generate an AC voltage, causing oscillator 52 to generate the AC voltage. This applies an AC voltage between first electrode 48 and second electrode 50, generating an AC electric field within shield case 44 (freezing / thawing compartment 12b), and the food is dielectrically heated by the alternating electric field.

[0045] While food is being heated in the heating space HZ, an alternating electric field is generated within the freezing / thawing compartment 12b. At this time, the shield case 44 shields the alternating electric field and prevents the alternating electric field from leaking out of the shield case 44 (freezing / thawing compartment 12b). To prevent the alternating electric field from leaking through the opening 44c on the front side of the shield case 44, a metal shield plate 12j that covers the opening 44c of the shield case 44 is provided on the door 12h, as shown in FIG. 1.

[0046] Furthermore, if the door 12h is not completely closed and therefore the alternating electric field may leak to the outside, the oscillator 52 is prohibited from applying an AC voltage between the first electrode 48 and the second electrode 50. That is, the oscillator 52 is enabled to generate an AC voltage only when the door sensor 32B detects the door 12h in a closed state. In this embodiment, when the control unit 30 receives a user's defrosting instruction via the user interface 34, if the door sensor 32B detects the door 12h in a closed state, the control unit 30 outputs a heating start signal to the oscillator 52. On the other hand, when the control unit 30 receives a user's defrosting instruction and the door sensor 32B does not detect the door 12h in a closed state, the control unit 30 does not output a heating start signal to the oscillator 52 and notifies the user via the user interface 34 to close the door 12h.

[0047] Furthermore, in the present embodiment, when door 12h is opened while oscillator 52 is generating an AC voltage (i.e., while food is being dielectrically heated), i.e., when door open / close sensor 32B can no longer detect door 12h in a closed state, oscillator 52, which is generating an AC voltage, stops generating the AC voltage. In the present embodiment, control unit 30 outputs a heating stop signal to oscillator 52, which causes oscillator 52 to stop generating the AC voltage.

[0048] Such control of AC voltage generation by oscillator 52 based on the open / closed state of door 12h prevents the AC electric field from leaking outside shield case 44 (freezing / thawing compartment 12b). In addition, in this embodiment, door open / close sensor 32B is a switch that detects door 12h in a closed state by coming into contact with door 12h, and is located outside shield case 44, so it is less susceptible to the AC electric field generated inside shield case 44. As a result, leakage of the AC electric field outside shield case 44 is reliably prevented.

[0049] Additionally, in this embodiment, as shown in FIG. 4, the heating module 40 further includes a drawer detection sensor 60 that detects the drawer 46. Specifically, the drawer detection sensor 60 detects the drawer 46 when the drawer 46 is in a predetermined position between the first electrode 48 and the second electrode 50. The "predetermined position" here refers to the position of the drawer 46 when the food to be heated contained in the drawer 46 is placed in the heating space HZ between the first electrode 48 and the second electrode 50. For this purpose, as shown in FIG. 3, a marker 46b is provided on the bottom surface 46a of the drawer 46 to indicate to the user the placement position of the food to be heated. That is, when the food to be heated is placed on the marker 46b and the drawer 46 is placed in the predetermined position, the food to be heated is placed in the heating space HZ between the first electrode 48 and the second electrode 50 and is appropriately dielectrically heated.

[0050] In this embodiment, as shown in Figures 3 and 4, drawer detection sensor 60 is a mechanical sensor that is provided on opening edge 42e of inner case 42 and comes into contact with front end 46c of drawer 46. As a result, drawer detection sensor 60 is provided outside freezing / thawing compartment 12b, i.e., outside shield case 44. This allows drawer detection sensor 60 to reliably detect drawer 46.

[0051] On the other hand, if the drawer detection sensor 60 were provided inside the freezing / thawing compartment 12b, i.e., inside the shielding case 44 where an alternating electric field is generated, the drawer sensor 60 could erroneously detect the drawer 46. For example, if the drawer sensor 60 were a Hall sensor that detects a magnetic field, it could malfunction due to the alternating electric field (magnetic field) generated inside the shielding case 44. Furthermore, if the drawer sensor 60 were a mechanical sensor, the contact surfaces of the drawer detection sensor 60 and the drawer 46 could stick to each other due to ice. Furthermore, the movable parts of the drawer detection sensor 60 could freeze and become unable to move properly. Therefore, the drawer detection sensor 60 is provided outside the radio wave irradiated space of the freezing / thawing compartment 12b, i.e., outside the space between the first electrode 48 and the second electrode 50.

[0052] In this embodiment, the oscillator 52 is enabled to generate an AC voltage only when the drawer detection sensor 60 detects that the drawer 46 is in a predetermined position. In this embodiment, the drawer detection sensor 60 is electrically connected to the oscillator 52. The oscillator 52 is in a standby state in which it is enabled to generate an AC voltage while it receives a detection signal from the drawer detection sensor 60 indicating that the drawer 46 is in a predetermined position. Then, upon receiving a heating start signal from the control unit 30, the oscillator 52 in a standby state starts generating an AC voltage. On the other hand, while it is not receiving a detection signal from the drawer detection sensor 60, the oscillator 52 does not generate an AC voltage even if it receives a heating start signal from the control unit 30.

[0053] Therefore, in this embodiment, when door sensor 32B detects door 12h in a closed state and drawer detection sensor 60 detects drawer 46 in a predetermined position, oscillator 32 generates an AC voltage to be applied between first electrode 48 and second electrode 50. As a result, even if door 12h is closed, if drawer 46 is not in a predetermined position and the food to be heated is not properly positioned in heating space HZ between first electrode 48 and second electrode 50, the start of dielectric heating is suppressed. As a result, insufficient thawing of food and unnecessary power consumption are suppressed.

[0054] If drawer 46 is pulled out from its predetermined position while oscillator 52 is generating an AC voltage (i.e., while food is being dielectrically heated), i.e., if drawer detection sensor 60 can no longer detect drawer 46 in its predetermined position, oscillator 52, which is generating an AC voltage, stops generating the AC voltage. In this embodiment, if it is no longer possible to receive a detection signal from drawer detection sensor 60, oscillator 52 stops generating the AC voltage.

[0055] In this embodiment, while oscillator 52 is generating AC voltage (i.e., while food is being dielectrically heated), door 12h must first be opened in order to pull out drawer 46 from its predetermined position. Therefore, once door 12h is opened, door open / close sensor 32B cannot detect door 12h in a closed state, and oscillator 52 stops generating AC voltage.

[0056] However, even when door 12h is open, there may be some reason, such as erroneous detection by door open / close sensor 32B, that causes oscillator 52 to generate AC voltage. In this case, if drawer 46 is pulled out from its predetermined position and drawer detection sensor 60 is no longer able to detect drawer 46 in its predetermined position, oscillator 52 will stop generating AC voltage.

[0057] As shown in Figure 4, the drawer detection sensor 60 is provided outside the freezing / thawing compartment 12b, i.e., on the opening edge 42e of the inner case 42, and detects (comes into contact with) the front end 46c of the drawer 46. The drawer detection sensor 60 can also be provided in a position other than the opening edge 42e of the inner case 42. That is, the drawer detection sensor 60 may be located in any position where it can detect a drawer 46 placed in a predetermined position. However, it is preferable to locate the drawer detection sensor 60 in a position where the drawer detection sensor 60 itself and wiring such as signal lines extending from the sensor are not significantly affected by the alternating electric field generated inside the shielding case 44. This prevents the drawer detection sensor 60 from malfunctioning due to the alternating electric field.

[0058] 1, the door sensor 32B, the control unit 30, and the oscillation unit 52 are located outside the shield case 44 of the heating module 40, where the alternating electric field is generated, and are therefore less susceptible to the alternating electric field generated inside the shield case 44. This prevents the door sensor 32B, the control unit 30, and the oscillation unit 52 from malfunctioning due to the alternating electric field.

[0059] Furthermore, even when the door 12h is open and the drawer 46 is not in its designated position, there is a possibility that the oscillator 52 may generate an AC voltage for some reason. To prevent the resulting AC electric field from leaking outside the shield case 44 (freezer / heating compartment 12b), the positions of the first electrode 48 and the second electrode 50 within the shield case 44 are specified. Specifically, as shown in FIG. 4, a distance D1 from the front end 50a of the second electrode 50 to the opening 44c of the shield case 44 is specified. This distance D1 will now be described in detail.

[0060] Fig. 7A is a diagram showing the simulation results of the spread of the alternating electric field in the front-rear direction, and Fig. 7B is a diagram showing the simulation results of the spread of the alternating electric field in the left-right direction.

[0061] 7A, the alternating electric field generated by the AC voltage applied between the first electrode 48 and the second electrode 50 spreads in the front-to-back direction (X-axis direction) within the shielding case 44. Also, as shown in Fig. 7B, the alternating electric field generated by the AC voltage applied between the first electrode 48 and the second electrode 50 spreads in the left-to-right direction (Y-axis direction) within the shielding case 44.

[0062] The electric field strength E [V / mm] of the alternating electric field generated between the first electrode 48 and the second electrode 50 can be simply expressed by the voltage V [V] between the first electrode 48 and the second electrode 50 and the distance D [mm] between the first electrode 48 and the second electrode 50 in the opposing direction (Z-axis direction), as shown in Equation 1.

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[0063] The voltage V can be expressed as Equation 2 using the output power W [w] of the oscillator 52 and the impedance Z [Ω]. The impedance Z is a fixed value and is a target impedance value to be adjusted by the matching circuit 56. By making the output impedance of the oscillator 52 equal to the impedance Z adjusted by the matching circuit 56, it is possible to suppress the reflection of radio waves. For example, the impedance Z is generally 50Ω.

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[0064] Therefore, the electric field strength E can be expressed as in Equation 3.

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[0065] The inventors have experimentally discovered Equation 4 as a condition for suppressing leakage of the alternating electric field generated by applying an AC voltage between the first electrode 48 and the second electrode 50 to the outside of the shielding case 44 through the opening 44c.

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[0066] Distance D1 from front end 50a of second electrode 50 to opening 44c of shielding case 44 is determined based on output power W and output impedance Z of oscillator 52 so as to satisfy Equation 4. Distance D1 determined in this manner makes it possible to prevent leakage of the alternating electric field outside shielding case 44, i.e., outside freezing / heating chamber 12b.

[0067] For example, if the impedance Z (output impedance of the oscillator 52) is 50Ω, the output power W is 100W, and the inter-electrode distance D is 100mm, making D1 greater than 17.67mm can suppress leakage of the alternating electric field outside the shield case 44, i.e., outside the freezing / heating chamber 12b.

[0068] 4 and 7A, a relatively high-intensity electric field is generated near the front end 48a of the first electrode 48, which is the end closer to the opening 44c of the shielding case 44. This occurs because the first electrode 48 is an electrode that is not connected to ground, unlike the second electrode 50. To prevent this relatively high-intensity electric field from leaking out of the shielding case 44 through the opening 44c of the shielding case 44, the front end 48a of the first electrode 48 is farther from the opening 44c of the shielding case 44 than the front end 50a of the second electrode 50, as shown in FIG.

[0069] 5, in the present embodiment, a distance D2 from a side end 50b in the left-right direction (Y-axis direction) of the second electrode 50 to an inner wall surface 44d of the shield case 44 is also defined in the same manner as the distance D1. Similar to the distance D1, the distance D2 is determined based on the output power W and output impedance Z of the oscillator 52 so as to satisfy the formula 5.

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[0070] Equations 4 and 5 for determining distances D1 and D2 are identical. However, unlike Equation 4, Equation 5 is not a conditional equation for suppressing leakage of the alternating electric field outside the shielding case 44. Equation 5 is a conditional equation for suppressing the formation of capacitance between the side end 50b of the second electrode 50 and the inner wall surface 44d of the shielding case 44. If distance D2 does not satisfy Equation 5, a large capacitance will be formed between the side end 50b of the second electrode 50 and the inner wall surface 44d of the shielding case 44. That is, the electric field generated at the side end 50b of the second electrode 50 reaches the inner wall surface 44d of the shielding case 44. As a result, radio waves leak through the shielding case 44, and part of the output power of the oscillator 52 is wasted for purposes other than generating the alternating electric field for dielectric heating the food. This reduces the efficiency of dielectric heating of the food. To suppress this leakage of radio waves and the reduction in dielectric heating efficiency, distance D2 is determined to satisfy Equation 5.

[0071] 5 and 7B, in the present embodiment, a relatively high-intensity electric field is generated near the side end 48b of the first electrode 48. If the side end 48b of the first electrode 48, where such a relatively high-intensity electric field is generated, is too close to the inner wall surface 44d of the shielding case 44, an extremely large capacitance is formed between the side end 48b and the inner wall surface 44d. To prevent an extremely large capacitance from being formed, the side end 48b of the first electrode 48 is farther away from the inner wall surface 44d of the shielding case 44 than the side end 50b of the second electrode 50.

[0072] According to the present embodiment as described above, leakage of an alternating electric field from the heating space of a refrigerator that dielectrically heats food to the outside can be suppressed.

[0073] Although the present invention has been described above with reference to the above-mentioned embodiment, the present invention is not limited to the above-mentioned embodiment.

[0074] For example, as shown in Figure 1, in the above-described embodiment, the door 12h is not connected to the drawer 46. However, the present invention is not limited to this embodiment.

[0075] FIG. 8 is a vertical cross-sectional view of a portion of a refrigerator according to another embodiment of the present invention.

[0076] As shown in FIG. 8, in a refrigerator 110 according to another embodiment, a door 112h that connects or separates the heating space HZ from the outside of the shield case 44 is connected to a drawer 46 that can be moved in and out of the heating space HZ. Therefore, when the door 112h is opened, the drawer 46 moves forward. In this case, the door 112h does not rotate about a rotation center line extending in the up-down direction (Z-axis direction), but is a door that can move parallel to the front-back direction (X-axis direction). Also, in this embodiment, the drawer detection sensor is omitted. Instead, the door opening / closing sensor 32B functions not only to detect whether the door 112h is open or closed, but also as a drawer detection sensor.

[0077] In the above-described embodiment, the heating space HZ for thawing food is a portion of the freezing / thawing compartment 12b for freezing food, as shown in Fig. 5. However, the present invention is not limited to this embodiment. The entire freezing / thawing compartment 12b may be the heating space HZ.

[0078] Furthermore, in the above-described embodiment, the first electrode 48 and the second electrode 50 face each other in the vertical direction (Z-axis direction) as shown in FIGS. 4 and 5. The second electrode 50 located on the lower side is connected to ground as shown in FIG. 6. However, this embodiment is not limited to this. For example, the first electrode and the second electrode may face each other in the vertical direction, with the upper first electrode connected to ground. Also, for example, the first electrode and the second electrode may face each other in the left-right direction (width direction of the refrigerator).

[0079] Furthermore, in the above-described embodiment, the freezing / thawing compartment 12b is provided within the heating module 40. That is, the heating module 40 is configured to be able to store food in a frozen state in addition to dielectrically heating the food. However, the present invention is not limited to this embodiment. The heating module 40 may be used only for dielectrically heating the food. In this case, there is no need to introduce cold air into the heating module 40.

[0080] That is, a refrigerator according to an embodiment of the present invention, in a broad sense, comprises a shielding case made of a metal material and having an opening on the front side that connects the inside and the outside, a flat-plate first electrode arranged within the shielding case, a flat-plate second electrode arranged within the shielding case so as to face the first electrode at a distance, forming a heating space between the first electrode and the flat-plate second electrode that dielectrically heats food and is connected to ground, and an oscillator unit that generates an AC voltage to be applied between the first electrode and the second electrode, wherein the distance D between the first electrode and the second electrode in the facing direction, the output power W of the oscillator unit, the output impedance Z of the oscillator unit, and the distance D1 from the front end of the second electrode to the opening of the shielding case are

number

[0081] The present invention is applicable to refrigerators capable of dielectrically heating food. [Explanation of symbols]

[0082] 44 Shield Case 44c opening 48 First electrode 50 Second electrode 50a front end D Opposite direction distance D1 Distance Z impedance W Output Power

Claims

1. a main body having a predetermined storage chamber; a shield case made of a metal material, which defines the predetermined storage chamber and has an opening on its front side that communicates between the inside and the outside; a drawer that is inserted into and removed from the shield case; a door for opening and closing the predetermined storage chamber; a door open / close sensor that detects a closed state of the door; a first electrode having a flat plate shape and disposed within the shield case; a flat-plate-shaped second electrode that is disposed in the shield case so as to face the first electrode with a gap therebetween, that forms a heating space between the first electrode and the second electrode for dielectrically heating food, and that is connected to ground; an oscillator that generates an AC voltage to be applied between the first electrode and the second electrode; a drawer detection sensor that detects that the drawer is at a predetermined position between the first and second electrodes; a distance D between the first electrode and the second electrode in the opposing direction, an output power W of the oscillator, an output impedance Z of the oscillator, and a distance D1 from the front end of the second electrode to the opening of the shielding case, [Equation 1] Satisfied, when the door open / close sensor detects that the door is closed and the drawer detection sensor detects that the drawer is in the predetermined position, the oscillator generates the AC voltage; the oscillating unit stops generating the AC voltage when the refrigerator is in at least one of a state in which the door opening / closing sensor does not detect a closed state of the door and a state in which the drawer detection sensor does not detect the drawer being at the predetermined position.

2. The refrigerator according to claim 1 , wherein a front end of the first electrode is farther from the opening of the shield case than a front end of the second electrode.

3. The opposing direction distance D, the output power W, the impedance Z, and the distance D2 from the side end of the second electrode to the inner wall surface of the shielding case are [Equation 2] 3. The refrigerator according to claim 1 or 2, which satisfies the above.

4. The refrigerator according to claim 3 , wherein a side end of the first electrode is farther from an inner wall surface of the shielding case than a side end of the second electrode.

5. The predetermined storage chamber is a freezing chamber for freezing food, The refrigerator according to claim 1 , wherein the heating space is at least a part of the freezer compartment.

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