JP2001255053A - Refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerator which can prevent the variation of the food preserving effect due to change in the capacitance at the storage side. SOLUTION: The refrigerator has a storage, freezer, inside fan, high voltage power source 8 and door switch 9. The high voltage power source 8 has a slide transformer 26 and a high voltage transformer 27. One end of the high voltage secondary winding of the transformer 27 is grounded through a series circuit of a high voltage resistor 28 and a high withstand voltage capacitor 29 which has a capacitance of 0.1 μF or less and is set to a higher value than the capacitance value determined by the wall, a shelf 2 and a shelf pillar 3 of the storage, and hence the preserving effect of food 1 can be made stable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator, and more particularly to a refrigerator for suppressing spoilage of food in a storage.

[0002]

2. Description of the Related Art As a conventional device of this type, there is a harmonic potential generator disclosed in Japanese Patent Publication No. 38-6106, for example. This device surrounds the outer periphery of the secondary wire loop of the transformer, and insulates rings of conductors such as copper from each other,
One end of the secondary side wire ring is closed and insulated, and only the other end is connected to the object to be processed. The preservative effect of the fresh food is intended to be obtained by harmonic electricity of 50 kV.

As a second conventional example, Japanese Patent Application Laid-Open No. Sho 54-2
There is a method for increasing the preservative power of food disclosed in Japanese Patent No. 6343. This technique has the effect that by applying a high electric field (about 3 to 50 kV) to foods, the preservation power of various foods can be increased about 2 to 10 times.

Further, as a third conventional example, Japanese Patent Publication No.
There is a method for thawing foods disclosed in Japanese Patent No. 7387. This method uses a high-voltage electrostatic transformer, completely blocks and insulates one pole on the secondary high-voltage side, provides a high output resistance to the other pole, and applies a 5000-20,000 V high-voltage negative electron to frozen food. Thaw quickly at a low temperature of -3 ° C to 3 ° C. The heat exchange between the outside and the inside of the frozen product can be performed smoothly without raising the temperature at all, and it can be kept fresh after thawing. It is possible to save for a period.

As a fourth conventional example, Japanese Patent Application Laid-Open No.
There is a food storage device disclosed in 297677.
This device is provided with a high-voltage power supply, and at least a high-voltage electric field forming electrode connected to the high-voltage power supply in the refrigerator compartment or the freezer compartment, and uses a shelf in the refrigerator compartment or the freezer compartment as the high-voltage electric field formation electrode. It has a mechanism. With this configuration, the life of the stored food can be efficiently and significantly prolonged without keeping the temperature low, and the effect of improving the taste is produced.

[0006]

However, in these prior arts, the difference in the preservative effect between the volume of the storage for storing the food and the electrode structure, particularly the influence of the capacitance of the storage, is taken into account. Did not.

Therefore, the inventors have designed a storage for storing foods placed on an internal shelf, a refrigerator for circulating cool air in the storage using a fan inside the storage, and a refrigerator for storing the food. Using a refrigerator having a high-voltage power supply for applying an AC high voltage between the grounded wall and the shelf, and a door switch for stopping driving of the high-voltage power supply when the door of the storage is open, The impedance of the storage side (including the high voltage cable and the heat insulating material) as viewed from the voltage power supply side was measured with an impedance meter, and the preservative effect of the food given the high electric field was observed.

As a result, (1) when cool air is circulated by the internal fan, the change in the cool air changes the capacitance value on the storage side, and the preservative effect of the food given a high electric field varies. (2) It has been found that the capacitance value on the storage side changes due to changes in the placement position of food in the storage and the type and amount of food, and the preservative effect of the food given a high electric field fluctuates. .

The cause is that the moisture in the cold air and the food are dielectric substances. If the capacitance on the storage side changes, matching with the output impedance of a high-voltage power supply (for example, a cut-core high-voltage transformer) cannot be obtained, and the electric field strength of the high electric field applied to the food changes, and the preservative effect of the food decreases. To fluctuate.

[0010] An object of the present invention is to provide a refrigerator based on the above knowledge, which can prevent a change in the preservative effect of food due to a change in capacitance of the storage side.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a storage for storing food placed on an internal shelf and circulating cool air in the storage using a fan in the storage. A refrigerator that cools and cools, a high-voltage power supply that supplies an AC high voltage between the grounded wall of the storage and the shelf, and a drive of the high-voltage power supply when the storage door is open. A high-voltage power supply having a slide switch to which an AC voltage of an external power supply is supplied and a high-voltage transformer to supply a variable output voltage output by the slide switch to a primary side. A first pole on the secondary high voltage side of the high voltage transformer is connected to the shelf via a shelf in the storage, and a second pole on the secondary high voltage side of the high voltage transformer is a high voltage resistor. And ground through a series circuit of The capacitance value of the high withstand voltage capacitor is 0.1 microfarad or less, and is set to be larger than the capacitance value determined by the wall of the storage, the shelf, and the shelf post. Is adopted.

In the present invention configured as described above,
The applied voltage can be adjusted by means of a slider, the first pole of the high-voltage transformer outputs the high voltage adjusted by the slider to the shelf, and the high-voltage resistor of the series circuit connected to the second pole of the high-voltage transformer , Limits the short-circuit current on the storage side, matches the load impedance, and
The high-withstand-voltage capacitor eliminates the influence of stray capacitance outside the refrigerator and matches the capacitance on the storage side. In addition, since it is 0.1 microfarad (μF) or less, an electric shock accident can be prevented. Thereby, the variation in the electric field intensity of the high electric field applied to the food is reduced, and the preservative effect of the food can be stabilized.

According to a second aspect of the present invention, in addition to the above configuration, the refrigerator controls the temperature in the storage at least by-
Cooling is performed at 4 ° C. to + 2 ° C., and the high-voltage power supply applies a high voltage of 500 V to 1500 V between the grounded wall of the storage and the shelf.

According to experiments, the energy applied to the moisture (cold air) and the food in the storage is proportional to frequency (f) × square of high voltage (V ² ) × dielectric constant (ε) × dielectric power factor (cos φ). , Dielectric constant (ε) × dielectric power factor (cos φ) is a function of frequency (f) and temperature (t), and since frequency (f) is a commercial power frequency of 50 Hz or 60 Hz,
The effective balance point for lowering the freezing point by oscillating the moisture (cold air) and the dipole of the food so as not to generate heat is the internal temperature -4.
It turned out that it becomes a combination of 500 degreeC-+2 degreeC and high voltage 500V-1500V. If the frequency f is quadrupled,
The same effect can be obtained even when the high voltage V is halved. Where ε
A difference is generated by the amount of change of × tanδ due to f.

Therefore, according to the second aspect of the present invention, the food can be preserved efficiently in addition to the first aspect.

Note that the distance d between the wall of the storage and the shelf is related to lowering the freezing point by reducing the cluster of water (H ₂ O) by oscillating the dipole of food (humidity and cold air). The effect of AC high voltage, that is, the effect of preserving food, is inversely proportional to the square of this distance d to the fourth power (1 / d ² to 1).
/ D ⁴ ). However, if the distance between the wall and the shelf is short, electric discharge occurs, a short circuit occurs through the dew condensation water, and the food placed on the shelf comes into contact with the wall to cause unevenness of the preservative effect, so that the preservative function cannot be performed. . In addition, the circulation of the cooling air deteriorates, which is the same.

From this fact, it was found that the distance d between the wall (metal charging part) of the storage and the shelf was 17 mm to 270 mm, which was suitable for preserving food. In this case, it is more effective to improve the circulation of the cooling air and improve the distribution of the electric field by using a shelf as a punching metal.

The invention according to a third aspect of the present invention is configured such that, in addition to the above configuration, an electrostatic shield is applied to a sensor for detecting the temperature in the storage.

With the above configuration, noise is removed, the temperature control performance is improved, and the control system is protected.

[0020]

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. FIG. 1 is a diagram showing a refrigerator, which has a capacity of 240 L (liter) to 2460 L.
Are provided. In the storage 4, food 1 is placed on a metal shelf 2 made of punched metal. 3. The shelf 3 is connected to one end of the output of the high-voltage power supply 8, and the other end of the output is connected to the metal wall 7 of the refrigerator. The metal wall 7 is grounded as indicated by reference numeral 12. Further, a door switch 9 for detecting the opening and closing of the door (not shown) and stopping the driving of the high-voltage power supply 8 when the door is open is provided behind the door (not shown). Have been. Further, a metal leaf spring is provided at the end of the door, and is connected to a metal wall on the main body side to prevent leakage of an electric field from the door.

On the other hand, a refrigerator 6 electrically connected to a metal wall 7 is provided above the storage 4. Thus, it is possible to prevent an error due to the floating capacity of the refrigerator 6, that is, a change in the storage effect of the food 1. An evaporator (not shown) of the refrigerator 6 is located in a refrigerator, and a drain pan 1 is discharged under the evaporator to be exposed to the dew during the static elimination.
5 are provided. The inside fan 5 is provided in a part of the drain pan 15 and circulates cool air near the evaporator in the storage case 4. A urethane foam portion 10 is provided as a heat insulating material inside the metal wall 7 (plate thickness of about 1 mm).
(With a thickness of about 40 to 45 mm), and a vinyl chloride plate 11 (with a thickness of about 5 mm to 10 mm) is provided inside the urethane foam part 10 as an electrical insulating material. The shelf 3 is screwed to the vinyl chloride plate 11. Reference numeral 14 denotes a drain port for discharging the dew water in the storage 4 to the outside. The diameter of the drain port is set to a dimension sufficiently shorter than the electromagnetic wavelength of the power supply 21 (for example, Or less).

Reference numeral 13 denotes a refrigerator leg. In this structure, the capacitance value on the storage 4 side is 100 pF to 300 pF.
It is about.

Further, a thermistor 16 for detecting the temperature in the refrigerator is provided near the fan 5 in the refrigerator. One end of the thermistor 16 is grounded and electrostatically shielded, and the other end is connected to the control device 17. Further, it is preferable to shield the inner wall surface and the suction pipe for returning the refrigerant by attaching aluminum tape. Since the thermistor 16 and its lead wire are electrostatically shielded, the thermistor 16 can accurately detect the internal temperature without error due to an electric field. The control device 17 drives the refrigerator 6 and the in-compartment fan 5 based on the temperature detection signal of the thermistor 16 to drive the inside of the storage 4 from -4 ° C to + 2 ° C.
To However, when the voltage signal supplied from the voltmeter 30 of the high-voltage power supply 8 is lower than 500 V, the control device 17 controls the refrigerator 6 and the refrigerator so that the inside of the storage 4 becomes + 1 ° C. to + 7 ° C. The inner fan 5 is controlled. Thereby, freezing of the food when the high voltage of 500 V to 1500 V is not supplied to the metal shelf 2 can be prevented.

FIG. 2 is a circuit diagram showing the high voltage power supply 8 of FIG. 1 and its peripheral circuits. In FIG. 2, a single-phase AC
Both ends of a 100 V commercial power supply 21 are two-pole breakers 22
a, 22b, and the other end of the breaker 22a is connected to the door switch 9 and the contact 24b of the relay 24. The other end of the breaker 22b is connected to an a contact 24c, like the primary coil 24a of the relay 24. The other end of the primary coil 24a is connected to the other end of the door switch 9. Contact 24b
The other end is connected to a lamp 25 for displaying electricity and a primary side of the eight sliders 26 of the high-voltage power supply. The other end of the contact 24c is the other end of the primary side of the lamp 25 and the slide buck 26,
It is connected to the primary side of the voltmeter 30 and the high voltage transformer 27 that display a maximum of 3 kV. The scale of the voltmeter 30 is the high voltage transformer 2
7 and a voltage signal proportional to this is supplied to the control device 17.

The sliding contact on the secondary side of the SLIDAC 26 is connected to the other end of the voltmeter 30 and the other end of the primary side of the high voltage transformer 27 having a turns ratio of 1:20 via a temperature fuse (cut off at 80 ° C.) 23. You. One end (first pole) on the secondary side of the high-voltage transformer 27 of the cut core is connected to the metal shelf 2 via the metal shelf 3 in the storage 4. On the other hand, the other end (second pole) on the secondary side of the high voltage transformer 27 is connected to a high voltage resistor 28 (having a resistance value of 3.3 MΩ to 5.1 MΩ) and a high voltage capacitor 29.
(The capacitance value is 0.01 μF to 0.1 μF). The other end of the series circuit is grounded via a metal wall 7.

Here, considering the case where the metal shelf 2 and the metal wall 7 are short-circuited, assuming that the resistance of the high-voltage resistor 28 is 3.3 MΩ at a high voltage of 1500 V, approximately 0.49 m
The short-circuit current is less than or equal to A, and this value is very weak. If the resistance value of the human body is about 5 kΩ, no harm to the human body is caused. Further, the capacitance value of the high withstand voltage capacitor 29 is set to 0.1
As μF, the discharge time constant with the resistance value of the human body of about 5 kΩ is a short time of 0.5 ms or less, and does not harm the human body.

Next, the operation of the embodiment shown in FIGS. 1 and 2 will be described. Now, when the power of the refrigerator is turned on, the control device 17 drives the refrigerator 6 and the internal fan 5 to set the inside of the storage 4 to + 1 ° C to + 7 ° C. In this state, the breaker 2 shown in FIG.
When the gates 2a and 22b are turned on, a current flows through the primary coil 24a of the relay 24 because the door (not shown) is closed, and the contacts 24b and 24c of the relay 24 are turned on. As a result, a voltage is applied to both ends of the lamp 25 and the lamp 25 is turned on. Then, the commercial power supply 21 (50/60 Hz, 100
V) is applied.

The sliding contact of the SLIDAC 26 is 25 V to 7
The voltage is set at one point between 5 V, and this voltage is supplied to the high-voltage transformer 27 through the thermal fuse 23 in the high-voltage transformer 27.
Is supplied to the primary coil. The voltmeter 30 displays the voltage of the sliding contact on a scale obtained by multiplying the voltage by 20 times (the winding ratio of the high-voltage transformer 27), and supplies a voltage signal by the controller 17. The control device 17 is 25 V or more (high-voltage transformer 27
Is determined to be 500 V or more), and the refrigerator 6 and the fan 5 in the refrigerator are driven so that the temperature in the storage 4 becomes −4 ° C. to + 2 ° C.

When high voltage transformer 27 is supplied with an AC voltage from SLIDAC 26, its secondary coil has a voltage of 500 V or more.
Outputs a voltage of 1500V. This voltage is supplied to the metal shelf 2 via the shelf 3 and is supplied to the food 1 on the metal shelf 2. The impedance of the series circuit composed of the high-voltage resistor 28 and the high-voltage capacitor 29 matches the load impedance (capacitance value is about 100 pF to 300 pF) of the storage 4 including the food 1. . When the volume of the storage 4 is 240 L (liter) to 2460 L at a temperature inside the storage of −4 ° C. to + 2 ° C., the resistance value of the high voltage resistor 28 is 3.3 MΩ to 5.1 MΩ, and The capacitance value of the high voltage capacitor 29 is 0.01
μF to 0.1 μF is suitable.

The food 1 on the metal shelf 2 is cooled to a temperature of −4 ° C. to + 2 ° C. in a state where the freezing point is lowered, and is stably stored in an electric field of almost AC high voltage 500 V to 1500 V. Does not rot more than twice when stored at temperature.

When the door (not shown) is opened to take out the food 1 from the storage 4, the door switch 9 is turned off,
When the driving of the relay 24 stops and the lamp 25 goes out, the voltage signal from the voltmeter 30 becomes less than 25 V, and the control device 1
7 is controlled so that the temperature in the refrigerator is + 1 ° C. to + 7 ° C.
That is, the refrigerator 6 and the internal fan 5 are not stopped. Also,
Since the output voltage of the high-voltage transformer 27 is 0 V, even if the user touches the shelf 2, there is no problem of electric shock. These 5, 6
Stops only during defrosting during operation. During the defrosting time, the evaporator of the refrigerator 6 generates heat to melt the frost, and the internal fan 5 stops. The output voltage of the slide rack 26 is manually or automatically increased by 25 V for this defrost time. As a result, even if the storage effect of the food by cooling is reduced, the storage effect by the high voltage is improved.

The position of the sliding contact of the slide contact 26 is automatically changed by a motor (not shown) connected to the sliding contact and a controller 17 for controlling the motor.

The set voltage of the slide rack 26 is calculated by converting the output voltage of the high-voltage transformer 27 into a storage volume of 480 L.
700V for 1060L, 900V for 1640L, 11 for 1640L
00V is preferred.

Further, the temperature in the storage is preferably set at -2 ° C for thawing and maintaining freshness of meat and seafood, -1 ° C for thawing and storing cakes, and + 1 ° C for storing vegetables and fruits.

[0035]

As described above, according to the first aspect of the present invention, the second pole on the secondary high voltage side of the high voltage transformer is grounded via a series circuit of a high voltage resistor and a high voltage capacitor. Since the capacitance value of the high-withstand voltage capacitor is 0.1 microfarad or less and is set to be larger than the capacitance value determined by the wall, the shelf, and the shelf column of the storage, the electric field strength of the high electric field applied to the food is reduced. Variation is reduced, and the preservative effect of food can be stabilized.

According to the second aspect of the present invention, the temperature in the storage is set to at least −4 ° C. to + 2 ° C., and a high voltage of 500 V to 1500 V is applied between the wall of the storage and the shelf. Therefore, in addition to the first aspect, preservation of food can be efficiently performed.

Further, according to the third aspect, it is possible to improve the accuracy of controlling the temperature in the refrigerator and obtain the effect of protecting the control system.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a refrigerator according to the present invention.

FIG. 2 is a circuit diagram showing a high-voltage power supply and its peripheral circuits in FIG. 1;

[Explanation of symbols]

 2 Metal Shelf 3 Shelf 4 Storage 5 Fan in Storage 6 Refrigerator 7 Metal Wall 8 High Voltage Power Supply 9 Door Switch 16 Thermistor 17 Control Device 26 Slidak 27 High Voltage Transformer 28 High Voltage Resistor 29 High Voltage Capacitor

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoshiaki Nishii 3-2-5 Kasumigaseki, Chiyoda-ku, Tokyo Daiwa Refrigerating Machinery Co., Ltd. F-term (reference) 3L045 AA02 AA04 AA05 AA07 BA01 CA02 DA02 EA01 KA11 LA17 NA15 PA04 PA06 4B022 LF02 LP01 LP10 LT06

Claims (3)

[Claims] 1. A storage for storing food on an internal shelf, a refrigerator for circulating cool air in the storage using an internal fan, and a grounding device for the storage. A high-voltage power supply that supplies an AC high voltage between a wall and the shelf, and a door switch that stops driving of the high-voltage power supply when the door of the storage is open, wherein the high-voltage power supply is And a high-voltage transformer for supplying a variable output voltage output from the external power supply to the primary side. A first pole on the secondary high-voltage side of the high-voltage transformer has The second pole on the secondary high voltage side of the high voltage transformer is connected to the shelf via a shelf in the storage, and is grounded via a series circuit of a high voltage resistor and a high voltage capacitor, The capacitance value of the high withstand voltage capacitor is 0.1 There is Rofarado below,
A refrigerator configured to set a capacitance value larger than a capacitance value determined by a wall of the storage, the shelf, and the shelf post. 2. The refrigerator cools the temperature in the storage to at least -4.degree. C. to + 2.degree. C., and the high-voltage power supply supplies 500 V to 15 V between a grounded wall of the storage and the shelf.
The refrigerator according to claim 1, wherein a high voltage of 00V is applied. 3. The refrigerator according to claim 1, wherein a sensor for detecting the temperature in the refrigerator is provided with an electrostatic shield.