JP7720530B2 - refrigerator - Google Patents

Description

The present invention relates to a refrigerator capable of dielectrically heating food.

For example, Patent Document 1 discloses a freezer that can thaw frozen food. The freezer in Patent Document 1 has a high-frequency heating chamber that stores the food to be thawed and heats the stored food with high-frequency waves (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 can be used as a freezer chamber.

Japanese Patent Application Laid-Open No. 2002-147919

However, 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.

The present invention aims to prevent leakage of alternating electric fields from the heating space of a refrigerator that dielectrically heats food to the outside.

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 disposed within the shield case;
a second electrode disposed in the shield case so as to face the first electrode with a gap therebetween, and forming a heating space between the first electrode and the second electrode for dielectrically heating food;
an oscillator that generates an AC voltage to be applied between the first electrode and the second electrode;
a door that communicates or separates the heating space from the outside of the shield case;
a first sensor that detects the door in a closed state, the door separating the heating space from the outside of the shield case;
When the first sensor detects the door in a closed state, the oscillator generates an AC voltage,
The refrigerator is provided in which, while the oscillator is generating the AC voltage, if the first sensor is no longer able to detect the door in a closed state, the oscillator stops generating the AC voltage.

This invention makes it possible to prevent leakage of alternating electric fields from the heating space of a refrigerator that dielectrically heats food to the outside.

FIG. 1 is a vertical cross-sectional view of a refrigerator according to an embodiment of the present invention; Block diagram showing the refrigerator control system Perspective view of the heating module Cross section of the heating module 5 is a cross-sectional view of the heating module taken along line AA shown in FIG. Block diagram showing the control system of the heating module A diagram showing the simulation results of the forward and backward spread of an alternating electric field. A diagram showing the simulation results of the horizontal spread of an alternating electric field. FIG. 10 is a vertical cross-sectional view of a portion of a refrigerator according to another embodiment of the present invention.

A refrigerator according to one aspect of the present invention comprises a shielding case made of a metal material and having an opening on the front side that connects the interior to the outside; a first electrode disposed within the shielding case; a second electrode disposed within the shielding case facing the first electrode at a distance and forming a heating space between the first electrode and the second electrode for dielectrically heating food; an oscillator that generates an AC voltage to be applied between the first electrode and the second electrode; a door that connects or separates the heating space from the outside of the shielding case; and a first sensor that detects the door in a closed state that separates the heating space from the outside of the shielding case. When the first sensor detects the door in a closed state, the oscillator generates an AC voltage; and when the first sensor is no longer able to detect the door in a closed state while the oscillator is generating the AC voltage, the oscillator stops generating the AC voltage.

This configuration makes it possible to prevent leakage of alternating electric fields from the heating space of the refrigerator, which dielectrically heats food, to the outside.

For example, the first sensor may be a sensor that detects the door in a closed state by coming into contact with the door.

For example, the first sensor may be disposed outside the shielding case. This prevents the first sensor from malfunctioning due to alternating electric fields generated within the shielding case.

For example, the oscillator may be located outside the shielding case. This prevents the oscillator from malfunctioning due to alternating electric fields generated within the shielding case.

For example, the refrigerator may further have a drawer that contains food to be heated and can be moved in and out of the heating space.

For example, the drawer may be connected to the door.

For example, the refrigerator may further include a second sensor that detects the drawer located at a predetermined position between the first electrode and the second electrode, and the oscillator may generate an AC voltage when the second sensor detects the drawer located at the predetermined position. If the oscillator is generating an AC voltage and the second sensor can no longer detect the drawer located at the predetermined position, the oscillator may stop generating the AC voltage. This allows food to be dielectrically heated when the food is appropriately placed in the heating space.

For example, the heating space may be at least a part of a freezer compartment in which food is frozen. This allows frozen food to be thawed directly.

The first sensor may be a Hall sensor located outside the shield case.

Below, a refrigerator according to one embodiment of the present invention will be described with reference to the drawings.

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

As shown in FIG. 1, the refrigerator 10 includes a main body 12. The main body 12 is composed of an outer casing 14 made of a metal material and constituting the outer surface of the refrigerator 10, an inner casing 16 made of a resin material such as ABS and constituting the inner surface of the refrigerator 10, and a thermal insulating material 18 such as rigid urethane foam that fills the space between the outer casing 14 and the inner casing 16.

The main body 12 of the refrigerator 10 has multiple storage compartments for storing food (ingredients, processed ingredients, etc.). In this 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 this embodiment, the freezer/thawing compartment 12b and the freezer compartment 12c are connected to each other.

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

In this embodiment, a machine room 12e is provided in the upper part of the main body 12 of the refrigerator 10. The machine room 8 contains components such as a compressor 20 that constitutes the refrigeration cycle of the refrigerator 10 and circulates the refrigerant for the refrigeration cycle. Alternatively, the machine room 12e can be provided in the lower part of the main body 12 of the refrigerator 10.

In this embodiment, a cooling compartment 12f is provided behind the freezer compartment 12c and vegetable compartment 12d. A cooler 22, through which a refrigerant passes, is located within the cooling compartment 12f and forms part of the refrigeration cycle of the refrigerator 10. A cooling fan 24 is also provided within the cooling compartment 12f, blowing the air (cold air) from the cooling compartment 12f cooled by the cooler 22 toward the refrigerator compartment 12a, freezer/thaw compartment 12b, freezer compartment 12c, and vegetable compartment 12d.

In this embodiment, the refrigerator 10 is provided with three doors 12g to 12i. Door 12g can be opened and closed, and connects or separates the refrigerator compartment 12a from the outside. Door 12h can be opened and closed, and connects or separates the freezer/thaw compartment 12b and the freezer compartment 12c from the outside. Door 12i can be opened and closed, and connects or separates the vegetable compartment 12d from the outside.

Furthermore, as shown in FIG. 2, dampers 26A-26C, which control the amount of cold air flowing into each of the compartments 12a-12d, are arranged in the flow path between each of the compartments 12a-12d and the cooling fan 24 (only damper 26B is shown in FIG. 1). Damper 26B is arranged in the flow path between the freezer/thaw compartment 12b and the cooling fan 24. The cold air passes through the freezer/thaw compartment 12b and flows into the freezer compartment 12c.

Furthermore, as shown in FIG. 2, the refrigerator 10 is equipped with temperature sensors 28A-28C that measure the internal temperatures of the refrigerator compartment 12a, the freezer/thaw compartment 12b, the freezer compartment 12c, and the vegetable compartment 12d, respectively.

As shown in FIG. 2, the refrigerator 10's control unit 30 performs cooling control based on the measurement results of multiple temperature sensors 28A-28C. This involves controlling the output of the compressor 20, the rotation speed of the cooling fan 24, and the opening and closing of each of the dampers 26A-26C, thereby maintaining appropriate temperatures in the refrigerator compartment 12a, freezer/thaw compartment 12b, freezer compartment 12c, and vegetable compartment 12d. The control unit 30 is, for example, a control board located in the machine compartment 12e and equipped with a processor such as a CPU, a storage device such as memory that stores programs, and circuits. The processor controls the compressor 20, cooling fan 24, and dampers 26A-26C according to the programs stored in the storage device.

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. The door sensors 32A-32C are, for example, switches that detect the closed state of the doors 12g-12i by contacting them. The door sensors 32A-32C are located on the main body 12 of the refrigerator 10 at positions that allow them to contact the inner surfaces of the doors 12g-12i. The detection signals from the door sensors 32A-32C are transmitted to the control unit 30. The control unit 30 controls the ON/OFF operation of lighting devices (not shown) installed in the refrigerator compartment 12a, freezer/thaw 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., non-contact switches. Magnetic sensors such as Hall sensors, MR sensors, and reed switches have the advantage that they are easier to miniaturize than mechanical switches and do not impair the design of the refrigerator 10 because they have no protrusions.

As shown in FIG. 2, in this embodiment, the refrigerator 10 is equipped with a user interface 34 that allows the user to operate the refrigerator 10. The user interface 34 may be a touch panel built into the refrigerator 10 and/or a mobile terminal of the user. If the user interface 34 is a mobile terminal, software (application) for operating the refrigerator 10 is installed on the mobile terminal.

For example, when one of the door open/close 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 freezer/thaw compartment 12b. Details of this freezer/thaw compartment 12b will now be explained.

Figure 3 is a perspective view of the heating module. Figure 4 is a cross-sectional view of the heating module. Figure 5 is a cross-sectional view of the heating module taken along line A-A in Figure 4. Figure 6 is a block diagram showing the control system of the heating module.

In this embodiment, the heating module 40 shown in Figures 3 to 5 is a module that heats frozen food and is incorporated into the refrigerator 10. The freezer/thaw compartment 12b is located within the heating module 40. As will be described in detail below, the heating module 40 is configured to generate an alternating electric field within the freezer/thaw compartment 12b and dielectrically heat the food using the alternating electric field.

As shown in Figures 3 to 5, the heating module 40 is a rectangular parallelepiped double-walled structure comprising 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 compartment in which food is stored, i.e., the freezing/thawing compartment 12b.

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 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 that connects the inside and outside, and stores the inner case 42 inside.

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

Furthermore, to enable the food in the freezer/thaw compartment 12b to be frozen, the inner case 42 and shield case 44 of the heating module 40 are provided with multiple ventilation holes 42b, 44a that communicate with the freezer/thaw compartment 12b. The cold air that passes through the damper 26B flows into the freezer/thaw compartment 12b via these ventilation holes 42b, 44a. This allows the food in the heating module 40, i.e., the freezer/thaw compartment 12b, to be frozen.

To dielectrically heat food in the freezer/thaw compartment 12b, e.g., to thaw frozen food, the heating module 40 includes a first electrode 48 and a second electrode 50.

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 within 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 of 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.

In this 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.

In this embodiment, the second electrode 50 is positioned on the bottom plate portion 42d of the inner case 42.

To form a 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 located 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 the AC voltage from the power supply 54 of the refrigerator 10, which 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.

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

In this embodiment, as shown in FIG. 6, the refrigerator 10 is equipped with 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.

The role of the matching circuit 56 will now be explained. As frozen food thaws, the number of water molecules within the food increases. This increase in water molecules causes the impedance between the first electrode 48 and the second electrode 50 to change from its appropriate value, increasing the reflectivity. Note that reflectivity is the ratio of the reflected wave returning to the oscillator 52 to the incident wave output from the oscillator 52. As reflectivity increases, the efficiency of dielectric heating of 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.

Specifically, as shown in FIG. 6 , the refrigerator 10 is equipped with a reflected wave detection circuit 58 so that the matching circuit 56 can maintain the impedance between the first electrode 48 and the second electrode 50 at an appropriate value. The reflected wave detection circuit 58 is provided, for example, on a circuit board located in the machine compartment 12e of the refrigerator 10. The control unit 30 calculates the reflectivity based on the incident wave output from the oscillator 52 and the reflected wave detected by the reflected wave detection circuit 58. Based on the calculated reflectivity, the control unit 30 controls the matching circuit 56 so that the impedance between the first electrode 48 and the second electrode 50 is maintained at an appropriate value.

When the user places the food to be heated in the heating space HZ of the freezer/thawing compartment 12b and issues a heating command to the user interface 34, the control unit 30 outputs a heating start signal to the oscillator unit 52, which generates an AC voltage. This applies an AC voltage between the first electrode 48 and the second electrode 50, generating an AC electric field within the shield case 44 (freezer/thawing compartment 12b), which dielectrically heats the food.

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 it from leaking outside 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, as shown in Figure 1, the door 12h is provided with a metal shield plate 12j that covers the opening 44c of the shield case 44.

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, it 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.

Furthermore, in this embodiment, when the door 12h is opened while the oscillator 52 is generating AC voltage (i.e., during dielectric heating of food), i.e., when the door open/close sensor 32B can no longer detect the door 12h in a closed state, the oscillator 52, which is generating AC voltage, stops generating that AC voltage. In this embodiment, the control unit 30 outputs a heating stop signal to the oscillator 52, which causes the oscillator 52 to stop generating AC voltage.

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

In addition, 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 it is located 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 item 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 reason, 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 item to be heated. In other words, when the food item to be heated is placed on the marker 46b and the drawer 46 is placed in the predetermined position, the food item is placed in the heating space HZ between the first electrode 48 and the second electrode 50 and is appropriately dielectrically heated.

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

On the other hand, if the drawer detection sensor 60 were installed inside the freezer/thaw chamber 12b, i.e., inside the shield 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 magnetic fields, it could malfunction due to the alternating electric field (magnetic field) generated inside the shield 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 become stuck together due to ice. Furthermore, the moving parts of the drawer detection sensor 60 could freeze and become unable to move properly. Therefore, the drawer detection sensor 60 is installed outside the radio wave irradiated space of the freezer/thaw chamber 12b, i.e., outside the space between the first electrode 48 and the second electrode 50.

In this embodiment, the oscillator 52 is enabled to generate 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 capable of generating AC voltage while receiving 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 begins generating AC voltage. On the other hand, while not receiving a detection signal from the drawer detection sensor 60, the oscillator 52 does not generate AC voltage even if it receives a heating start signal from the control unit 30.

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

If the drawer 46 is pulled out from its designated position while the oscillator 52 is generating AC voltage (i.e., while food is being dielectrically heated), i.e., if the drawer detection sensor 60 can no longer detect the drawer 46 in its designated position, the oscillator 52, which is generating AC voltage, will stop generating that AC voltage. In this embodiment, the oscillator 52 stops generating AC voltage when it can no longer receive a detection signal from the drawer detection sensor 60.

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

However, even when the door 12h is open, for some reason, such as a false detection by the door open/close sensor 32B, the oscillator 52 may generate an AC voltage. In this case, if the drawer 46 is pulled out from its designated position and the drawer detection sensor 60 is no longer able to detect the drawer 46 in its designated position, the oscillator 52 will stop generating an AC voltage.

As shown in FIG. 4, the drawer detection sensor 60 is located 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 located in a position other than the opening edge 42e of the inner case 42. That is, the drawer detection sensor 60 need only be located in a 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 the wiring, such as signal lines, extending from the sensor are not significantly affected by the alternating electric field generated within the shielding case 44. This prevents the drawer detection sensor 60 from malfunctioning due to the alternating electric field.

Regarding the effects of alternating electric fields, as shown in Figure 1, the door opening/closing sensor 32B, control unit 30, and oscillation unit 52 are located outside the shielding case 44 of the heating module 40, where the alternating electric field is generated, and are therefore less susceptible to the effects of the alternating electric field generated within the shielding case 44. This prevents the door opening/closing sensor 32B, control unit 30, and oscillation unit 52 from malfunctioning due to the alternating electric field.

Moreover, even if 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 second electrode 50 within the shield case 44 are specified. Specifically, as shown in Figure 4, the 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 be explained in detail below.

Figure 7A shows the simulation results of the spread of the alternating electric field in the forward and backward directions. Figure 7B shows the simulation results of the spread of the alternating electric field in the left and right directions.

As shown in FIG. 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. 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.

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.

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, which 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.

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

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 shield case 44 through the opening 44c.

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

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

As shown in Figures 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 closest to the opening 44c of the shielding case 44. This occurs because the first electrode 48, unlike the second electrode 50, is an electrode that is not connected to ground. 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, as shown in Figure 4, 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.

5, in the present embodiment, the distance D2 from the side end 50b in the left-right direction (Y-axis direction) of the second electrode 50 to the 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.

Equations 4 and 5 used to determine 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 shield 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 shield case 44. If distance D2 does not satisfy Equation 5, a large capacitance will form between the side end 50b of the second electrode 50 and the inner wall surface 44d of the shield 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 shield case 44. As a result, radio waves leak through the shield 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.

In this embodiment, as shown in Figures 5 and 7B, 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, comes too close to the inner wall surface 44d of the shielding case 44, an extremely large capacitance will be 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.

According to this embodiment, it is possible to prevent leakage of alternating electric fields from the heating space of the refrigerator, which dielectrically heats food, to the outside.

The present invention has been described above using the above-mentioned embodiments, but the present invention is not limited to these embodiments.

For example, as shown in Figure 1, in the embodiment described above, the door 12h and the drawer 46 are not connected. However, embodiments of the present invention are not limited to this.

Figure 8 is a longitudinal cross-sectional view of a portion of a refrigerator according to another embodiment of the present invention.

As shown in Figure 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 vertical direction (Z-axis direction), but rather is a door that can move parallel to the front-to-back direction (X-axis direction). Also, in this embodiment, the drawer detection sensor is omitted. Instead, the door opening/closing sensor 32B not only detects whether the door 112h is open or closed, but also functions as a drawer detection sensor.

Furthermore, in the above-described embodiment, as shown in FIG. 5, the heating space HZ for thawing food is a portion of the freezing/thawing compartment 12b in which food is frozen. However, embodiments of the present invention are not limited to this. The entire freezing/thawing compartment 12b may also be the heating space HZ.

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 Figures 4 and 5. The second electrode 50 located on the lower side is connected to ground as shown in Figure 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).

Furthermore, in the above-described embodiment, a freezing/thawing compartment 12b is provided within the heating module 40. That is, the heating module 40 is configured to not only dielectrically heat food but also freeze and store food. However, embodiments of the present invention are not limited to this. The heating module 40 may be used only for dielectrically heating food. In this case, there is no need to introduce cold air into the heating module 40.

That is, broadly speaking, a refrigerator according to an embodiment of the present invention comprises a shielding case made of a metal material and having an opening on the front side that connects the interior to the outside; a first electrode disposed within the shielding case; a second electrode disposed within the shielding case facing the first electrode at a distance and forming a heating space between the first electrode and the second electrode for dielectrically heating food; an oscillator that generates an AC voltage to be applied between the first electrode and the second electrode; a door that connects or separates the heating space from the outside of the shielding case; and a first sensor that detects the door in a closed state that separates the heating space from the outside of the shielding case. When the first sensor detects the door in a closed state, the oscillator generates an AC voltage, and when the first sensor can no longer detect the door in a closed state while the oscillator is generating the AC voltage, the oscillator stops generating the AC voltage.

This invention can be applied to refrigerators that can heat food dielectrically.

10 Refrigerator 12h Door 32B First sensor (door opening/closing sensor)
44 Shield case 48 First electrode 50 Second electrode 52 Oscillator

Claims (7)

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 disposed within the shield case;
a second electrode disposed in the shield case so as to face the first electrode with a gap therebetween, and forming a heating space between the first electrode and the second electrode for dielectrically heating food;
an oscillator that generates an AC voltage to be applied between the first electrode and the second electrode;
a door that communicates or separates the heating space from the outside of the shield case;
a first sensor that detects the door that separates the heating space from the outside of the shield case in a closed state;
a drawer that accommodates food to be heated and that can be moved in and out of the heating space;
a second sensor for detecting the lead-out at a predetermined position between the first electrode and the second electrode;
When the first sensor detects the door in a closed state, the oscillator generates an AC voltage,
When the first sensor is unable to detect the door in a closed state while the oscillator is generating the AC voltage, the oscillator stops generating the AC voltage ,
When the second sensor detects the drawer present at the predetermined position, the oscillator is capable of generating an AC voltage,
When the second sensor is unable to detect the drawer present at the predetermined position while the oscillator is generating the AC voltage, the oscillator stops generating the AC voltage .
2. The refrigerator according to claim 1, wherein the first sensor is a sensor that detects the door in a closed state by contacting the door.
3. The refrigerator according to claim 1, wherein the first sensor is disposed outside the shield case.
The refrigerator according to claim 1 , wherein the oscillation unit is disposed outside the shield case.
The refrigerator of claim 1 , wherein the drawer is connected to the door.
The heating space is at least a part of a freezing compartment in which food is frozen.
The refrigerator according to claim 1 .
The refrigerator according to claim 1 , wherein the first sensor is a Hall sensor disposed outside the shield case.