WO2008153285A2

WO2008153285A2 - Supercooling apparatus and method for controlling the same

Info

Publication number: WO2008153285A2
Application number: PCT/KR2008/003136
Authority: WO
Inventors: Su-Cheong Kim; Jong-Min Shin; Deok-Hyun Youn; Cheol-Hwan Kim; Won-Young Chung; Hoon-Bong Lee
Original assignee: Lg Electronics, Inc.
Priority date: 2007-06-11
Filing date: 2008-06-04
Publication date: 2008-12-18
Also published as: WO2008153285A3

Abstract

A supercooling apparatus includes a refrigeration cycle; a non-freezing chamber (200) to which chilled air from the refrigeration cycle is introduced, for storing an item; and a pair of electrodes (230) for applying an electric field to the non-freezing chamber (200), the electrodes (230) being arranged at an adjustable spacing therebetween according to characteristics of food to be stored. This configuration makes it possible to control the intensity of an expected electric field that varies depending on the size, moisture content, etc, of a stored item, by adjusting the spacing between the electrodes (230). Moreover, if a stored item is bulky, the spacing between the electrodes can be increased.

Description

SUPERCOOLING APPARATUS AND METHOD FOR CONTROLLING THE SAME

Technical Field

[1] The present invention relates to a supercooling apparatus with a non-freezing chamber to store items in a supercooled state. More specifically, the present invention relates to a supercooling apparatus having a pair of electrodes, arranged at an adjustable distance from each other, for applying an electric field energy to let stored items stay in a non-frozen state. Background Art

[2] Supercooling is a phenomenon that a liquid is not transited to a solid even below its phase transition temperature but maintained in a high temperature phase, i.e. a liquid phase. For example, water drops are supercooled in natural conditions. Incidentally, water or a beverage does not freeze but may remain in a supercooled state even in a freezer compartment of the ordinary refrigerator. A freezing method disclosed under Japan Laid-Open Patent Official Gazette S59-151834 and a freezing method and a refrigerator disclosed under Japan Laid-Open Patent Official Gazette 2001-086967 incorporate supercooling principles into the refrigerator. Both provide a technique for keeping foods in a supercooled state below the phase transition temperature by applying an electric field or a magnetic field to the foods in the refrigerator. Moreover, an electrostatic field treatment method disclosed under International Publication Official Gazette WO/98/41115 suggests diverse types of electrode structures that are suitable for freezing and thawing foods.

[3] FIG. 1 shows one example of a refrigerator with a special refrigeration container as disclosed in Korean Patent Application Publication No. 2003-0038999. A refrigerator body 10 includes a freezer compartment 20, a refrigerator compartment 30, a special refrigeration container 40 located at the bottom of the refrigerator compartment 30, and freezer and refrigerator doors 21 and 31 hinged to the body 10 to access the freezer compartment 20 and the refrigerator compartment 30, respectively.

[4] The special refrigeration container 41 is a space for keeping perishable foods such as fish, meat, etc. This special room comes in handy especially when one does not want to spend so much additional time for thawing frozen fish, meat or poultry having been kept in the freezer compartment 20.

[5] The special refrigeration container 41 is a space for keeping perishable foods such as fish, meat, etc. This special room comes in handy especially when one does not want to spend so much additional time for thawing frozen fish or meat having been kept in the freezer compartment 20.

[6] Nevertheless, the special refrigeration container having a lower temperature than the refrigeration chamber in a conventional refrigerator is not yet suitable to keep seafood or meat for a long period of time because it is not chiller than the freezer compartment. Therefore, a user has to put fish or meat into the freezer compartment anyway if she wants to preserve it longer than several tens of hours, and this leaves the inconvenience of thawing unsolved.

[7] Therefore, the development of a supercooling apparatus with a non-freezing chamber to store items at a phase transition temperature of liquid or below without causing the stored items to freeze is under progress. The non-freezing chamber receives energy through an electric field from electrodes and uses the energy to prevent the phase transition of liquid in a stored item, so that the stored item does not freeze yet can be preserved for an extended period of time. Meanwhile, the non-freezing chamber is kept at low temperatures while in operation, and its relative humidity is very high because of the moisture contained in the stored item. This resultantly forms frost on the electrodes. The frost on the electrodes serves as an interfering substance of the generation of an electric field between the electrodes, and impairs energy efficiency. Besides, the frost becomes a freezing nucleus of liquid inside the non-freezing chamber, causing the stored items to freeze. Moreover, if the electrodes are not frosted evenly, this poses a problem that an electric field is applied non-uniformly into the non-freezing chamber, depending on positions in the chamber.

[8]

Disclosure of Invention

Technical Problem

[9] The present invention is conceived to solve the aforementioned problems in the prior art. An object of the present invention is to provide a supercooling apparatus having a pair of electrodes with an adjustable spacing between them. [10] Another object of the present invention is to provide a supercooling apparatus capable of controlling the intensity of an electric field applied into a non-freezing chamber by adjusting spacing between the electrodes. [11] Still another object of the present invention is to provide a supercooling apparatus capable of controlling the intensity of an electric field through adjustment of voltage being applied depending on spacing between the electrodes. [12] Yet another object of the present invention is to provide a method for controlling the supercooling apparatus.

Technical Solution [13] According to an aspect of the present invention, there is provided a supercooling apparatus, including a refrigeration cycle; a non-freezing chamber to which chilled air from the refrigeration cycle is introduced, for storing an item; and a pair of electrodes for applying an electric field to the non-freezing chamber, the electrodes being arranged at an adjustable spacing therebetween according to characteristics of food to be stored. With this configuration, it becomes possible to control the intensity of an expected electric field that varies depending on the size, moisture content, etc, of a stored item, by adjusting the spacing between the electrodes. Moreover, if a stored item is bulky, the spacing between the electrodes can be increased.

[14] In an exemplary embodiment of the present invention, the supercooling apparatus further includes a storage container being inserted into/taken out from the non-freezing chamber, for storing an item. Through this configuration, the spacing between the electrodes is adjusted and direct contacts between a stored item and the electrodes can be avoided.

[15] In an exemplary embodiment of the present invention, the spacing between the pair of electrodes is adjusted depending on size of the storage container( which is housed in the non-freezing chamber). For instance, a plural number of replaceable storage containers of different size can be used. This allows a user to select a storage container with an appropriate size for the food to be stored in the non-freezing chamber. As the spacing between the electrodes is adjusted depending on the size of a storage container, the same is done according to the size of food.

[16] In an exemplary embodiment of the present invention, the supercooling apparatus further includes a sensor for detecting the intensity of an electric field inside the non- freezing chamber. With this configuration, one can monitor whether the electric field intensity inside the non-freezing chamber satisfies the condition for maintaining a supercooled state of stored items.

[17] In an exemplary embodiment of the present invention, the supercooling further includes a power supply for supplying a voltage level regulated depending on the intensity of an electric field. Therefore, if the current electric field intensity is lower than an optimal level, the applied voltage is increased. On the other hand, if the current electric field intensity is higher than an optimal level, the applied voltage is decreased until it reaches the optimal voltage level.

[18] In an exemplary embodiment of the present invention, the supercooling apparatus further includes a means for detecting a distance between the electrodes. Based on the detected distance between the electrodes, a voltage level to be applied to the electrodes is regulated accordingly, and the electric field intensity is adjusted to an optimal value.

[19] In an exemplary embodiment of the present invention, the distance between the electrodes is adjusted to cause the intensity of an electric field to be applied to the storage container to fall within a predetermined range. [20] In an exemplary embodiment of the present invention, the supercooling apparatus further includes a resilient member for transmitting a resilient force to the electrodes to adjust the spacing between the electrodes. For instance, a tension spring may be provided between the electrodes, so that the distance between the electrodes can be adjusted by a resilient force from the spring according to the size of an item to be stored.

[21] In an exemplary embodiment of the present invention, the supercooling further includes a motor for adjusting the spacing between the pair of electrodes. Examples of such motor include a timing belt, a chain, a gear, and so on. According to this configuration, the motor, usually in fixed state, can move the electrodes, and one single motor is sufficient to move a pair of electrodes.

[22] Another aspect of the present invention provides a method for controlling a supercooling apparatus with a pair of electrodes arranged at an adjustable spacing therebetween, the method including; a first step for detecting size of a storage container positioned in a non-freezing chamber; and a second step for adjusting spacing between the electrodes. With this method, the spacing between the electrodes can be adjusted according to the size of a storage container.

[23] In an exemplary embodiment of the present invention, the first step includes: a first process of deciding whether the storage container is fully inserted; and a second process of detecting size of the container. According to this method, the electrodes would not move until a user slides the storage container fully into the supercooling apparatus. In result, safety in the use of the apparatus is improved.

[24] In an exemplary embodiment of the present invention, the method further includes: a third step for detecting an electric field intensity being applied to the storage container; and a fourth step for regulating a voltage level being applied to the electrodes. Through this method, although the distance between the electrodes may have been changed, the electric field intensity can be adjusted to maintain the supercooled state of a stored item.

[25] Still another aspect of the present invention provides a method for controlling a supercooling apparatus with a pair of electrodes arranged at an adjustable spacing therebetween, the method including: a first step for detecting a distance between the electrodes; and a second step for regulating a voltage level being applied to the electrodes. Considering that, under the same conditions, the intensity of an electric field increases as the electrodes are brought closer to each other, it can still be adjusted to an optimal value despite the change in the distance between the electrodes. When the electrodes are close to each other and the electric field intensity being applied between the electrodes is high, corona discharge is likely to occur, causing a stored item to be spoiled. Therefore, a voltage level should be reduced as the electrodes are brought close to each other, thereby maintaining the electric field intensity at an optimal value.

[26] Still another aspect of the present invention provides a method for controlling a supercooling apparatus with a pair of electrodes arranged at an adjustable spacing therebetween, the method including: a first step for detecting an electric field intensity being applied to non-freezing chamber; and a second step for adjusting a distance between the electrodes. As such, the electric field intensity being applied to a non- freezing chamber can be controlled to an optimal value by adjusting the distance between the electrodes.

[27] Yet another aspect of the present invention provides a method for controlling a supercooling apparatus with a pair of electrodes arranged at an adjustable spacing therebetween, the method including: a first step for adjusting a distance between the electrodes; and a second step for regulating a voltage level being applied to the electrodes. Through this method, a voltage level is set in a manner to increase as the distance between the electrodes is increased. In result, the intensity of an electric field can be set to an optimal value.

Advantageous Effects

[28] According to the supercooling apparatus and its control method of the present invention, it is possible to adjust the spacing between the electrodes depending on the amount, kind, and size of an item to be stored in the non-freezing chamber. This also enables to control the electric field intensity to be applied to the non-freezing chamber.

[29] The supercooling apparatus and its control method of the present invention adjust the voltage level according to the spacing between the electrodes, so that the electric field may not increase too high, or decrease too low and corona discharge may not occur.

[30] The supercooling apparatus and its control method of the present invention detect the electric field intensity being applied between the electrodes to adjust the spacing between them.

[31] Lastly, the supercooling apparatus and its control method of the present invention adjust the spacing between the electrodes based on the size of a storage container used for the non-freezing chamber. Thus, the distance between each electrode and the storage container can be maintained at an appropriate range.

Brief Description of the Drawings

[32] FIG. 1 shows one example of a conventional refrigerator with a special refrigeration container; [33] FIG. 2 shows a schematic view of a non-freezing chamber provided to a supercooling apparatus of the present invention, in which the non-freezing chamber has electrodes with an adjustable spacing between them; [34] FIG. 3 and FIG. 4 show supercooling apparatuses having a non-freezing chamber with electrodes arranged at an adjustable spacing between them, in accordance with a first embodiment of the present invention;

[35] FIG. 5 shows a supercooling apparatus having a non-freezing chamber with electrodes arranged at an adjustable spacing between them, in accordance with a second embodiment of the present invention; and

[36] FIG. 6 through FIG. 11, respectively, show flow charts describing methods for controlling a supercooling apparatus having electrodes arranged at an adjustable spacing between them, in accordance with first through sixth embodiments of the present invention.

[37]

Mode for the Invention

[38] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[39] FIG. 2 illustrates a schematic view of a non-freezing chamber provided to a supercooling apparatus of the present invention, in which the non-freezing chamber has electrodes with an adjustable spacing between them. A pair of electrodes 230 are provided to both lateral sides of a non-freezing chamber 200 to apply an electric field into the chamber, and a power supply 232 is connected to the electrodes 230 to impress high- voltage AC power to them. Distance or spacing between the electrodes 230 can be adjusted according to the size of a storage container 210 housed in the non-freezing chamber 200. This is done by a distance regulation member 234 installed between the electrode pair 230. One example of the simple form of the distance regulation member 234 is a resilient element, but a motor or a power transfer unit may be used as well. The storage container 210 lodged in the non-freezing chamber 200 may be composed of a plurality of replaceable containers of various sizes, so a user can select a suitable container 210 of proper size depending on the size of a target item to be stored in the non-freezing chamber 200. When a selected storage container 210 is taken in the non- freezing chamber 200, spacing between the electrodes 230 is then adjusted according to the size of the storage container 210. Therefore, the distance between the storage container 210 and the electrode 230 can be maintained within a predetermined range. As aforementioned, a resilient member may be provided between the electrodes 230 to have them maintain the predetermined distance from the storage container 210 by a restoring force. In addition, the size of the storage container 210 being inserted into the non-freezing chamber 200 can be detected to actuate a motor. Therefore, given that the distance between the electrode 230 and the storage container 210 is adjusted to fall within an expected range, the electrodes 230 that receive power from the power supply can melt away the frost formed in the storage container 210 by thermal energy generated by an electric field. If the spacing between the storage container 210 and the electrode 230 is narrow, an electric field is supplied into the storage container 210 more stably and power efficiency can be increased.

[40] Provided that the same voltage is applied to the electrodes 230, the narrower the spacing between the electrodes 230 is, the stronger the intensity of an electric field between the electrodes 230 is. That is, the electric field intensity can be controlled by regulating the distance between the electrodes 230. In other words, the distance between the electrodes 230 can be adjusted to control the intensity of an electric field.

[41] FIG. 3 and FIG. 4 respectively show a supercooling apparatus having a non-freezing chamber with electrodes arranged at an adjustable spacing between them, in accordance with a first embodiment of the present invention. The supercooling apparatus includes a non-freezing chamber 200 which can preserve food at the water's phase transition temperature or below without freezing moisture contained in the food. The non-freezing chamber 200 is defined by an outer casing 220, a hexahedron shape box with an open top.

[42] The electrode panels 236, to which the electrodes 230 are attached, are movably arranged inside the outer casing 220 to adjust the distance in between them. A chilled air inflow hole 242 and a chilled air outflow hole 244 are formed at the lateral face or the rear face of the outer casing 220. The chilled air outflow hole 244 may be formed on the top face of the outer casing 220 instead of the lateral or rear face, so that the chilled air having cooled off the non-freezing chamber 200 may be discharged to the refrigeration compartment.

[43] Foods are stored in the outer casing 220, or in the non-freezing chamber 200 to be specific. If the electrodes 230 come in direct contact with a stored item, current is applied to the item and a user can be at the risk of electric shock. Moreover, as the electrodes 230 generate heat, the supercooled state of the food may be released, or gets burned in a worse case. Therefore, foods should be kept at a distance from the electrodes 230 when they are to be preserved in the non-freezing chamber 200. To prevent the direct contact between the stored item and the electrodes 230, a storage container 210 is slid into the outer casing 220 to keep the stored item. The storage container 210 has a drawer shape with an open top, so that the user can easily place the stored item in it.

[44] The storage container 210 is also designed to be taken out of the outer casing 220.

The storage container 210 and each the electrode panels 236 include a guide member 280 (282 and 284) to guide the motion of the storage container 210. In this embodiment, the electrode panels 236 have a guide rib 282, while the storage container 210 has a guide groove 284, or vice versa. [45] A handle 290 is formed at the front side of the storage container 210 to let the user easily pull out (or slide out) the storage container 210 from the outer casing 220. A cavity or a protrusion formed at the front side of the storage container 210 can serve as the handle. The handle 290 can be integrally manufactured with the storage container 210.

[46] Since the chilled air flows into the outer casing 220, the electrodes 230 and the inner faces of the outer casing 220 can be frosted. When this occurs, the intensity of an electric field applied by the electrodes 230 may become weak, and energy efficiency is impaired. Further, the storage container 210 is not easily slid out or taken out because of the frost formed on the inner faces of the outer casing 220. Especially when the frost is dropped into the storage container 210, or the non-freezing chamber 200, it functions as a freezing nucleus, causing the food to freeze. Thus, the frost needs to be removed. To this end, the supercooling apparatus includes a defrosting device 250 to get rid of the frost formed on the electrodes 230. One of typically used defrosting devices is a heater. For a defrosting process, power supply to the electrodes 230 is cut off, and the heater is turned on to melt the frost. In result of the defrosting process by the heater, the frost melts, turning into water. It is important to discharge this defrosted water immediately because it may freeze again to form frost, and create a non-hygienic state. This is why a drain hole 260 is formed at the bottom of the outer casing 220. The drain hole 260 is connected to a drain passage (not shown) to discharge the defrosted water to the outside.

[47] A sensor 170 is installed to detect a state of the non-freezing chamber 200. In detail, the sensor 270 detects temperature of the non-freezing chamber 200 and the intensity of an electric field applied to the non-freezing chamber 200. The sensor detects the temperature and the electric field intensity continuously to ensure that the non-freezing chamber 200 stays in a supercooled condition, and transmits the detection results to a controller (not shown). The controller (not shown) then controls the inflow rate and temperature of the chilled air and the voltage to be applied to the electrodes 230, based on the received information. The controller (not shown) judges whether or not to defrost the electrodes 230 because it makes the defrosting device 250 start operating. If the sensor 270 is able to detect the size of a storage container 210 being slid into the outer casing 220, the controller can control the spacing between the electrodes 230 by moving the electrode panels 236 in accordance with the size of the storage container 210. The outer casing 220 is either made out of an insulating material, or contains an insulation layer.

[48] In the outer casing 220, the distance between the electrode panels 236 is adjusted according to the size of the storage container 210 being slid in the casing 220. Depending on the kind, size, and characteristics of food, the user may use a plurality of the storage containers 210. When the storage container 210 is slid in the outer casing 220, the resilient member 234a installed at the outer casing 220 pushes the electrode panels 236 using its resilient force, so that a predetermined spacing is maintained between the electrode panels 236 and the storage container 210. Guide ribs 236a are formed at least one of the top and bottom faces of the outer casing 220 to guide the motion of the electrode panels 236, and the electrode panels 236 have guide grooves 236b to receive the guide ribs 236a. Also, the electrode panels 236 or the storage container 210 may have space maintaining projections to let the outer casing 220 and the storage container 210 separated a fixed distance apart. If the space maintaining projections are not available in the outer casing 220 or the storage container 210, the outer casing 220 and the storage container 210 come in contact with each other by the resilient force of the resilient member 236. Through this configuration, the spacing and electric field intensity between the electrodes can be adjusted according to the characteristics of a stored item. Moreover, since the electrodes 230 and the storage container 210 are arranged within a predetermined range of distance from each other, the heat- generating electrodes 230 defrost the storage container 210. Meanwhile, the electric field intensity between the electrodes 230 can be adjusted by controlling a voltage level applied from a power supply (232 in FIG. 2) to the electrodes 230. When an electric field is generated at a lower voltage with the spacing between the electrodes 230 being reduced, the power efficiency is increased. [49] FIG. 5 shows a supercooling apparatus having a non-freezing chamber with electrodes arranged at an adjustable spacing between them, in accordance with a second embodiment of the present invention. The second embodiment differs from the first embodiment in that a motor 234b and a belt 234c are used in replacement of the resilient member 234a(shown in FIG. 3). The motor 234b transmits its driving force to the electrode panels 236 via the belt 234c. According to the second embodiment, only one side of the outer casing 220 moves by the driving force transmitted via one belt 234c that is connected to one motor 234b. However, it is also possible to connect a plural number of belts 234c to one motor 234b to cause both sides of the outer casing 220 to move. Further, a plural number of belts 234c can be connected to a plural number of motors 234b. When the motor 234b is in charge of regulating the gap between both sides of the outer casing 220, i.e. the spacing between the electrodes 230, a function of detecting the size of a storage container 210 is added to a sensor 270, so that the spacing between the electrode 230 is automatically adjusted based on the size of the storage container 210. A command for driving the motor 238 may be input by means of an operation unit (not shown) to have the spacing between the electrodes 230 adjusted. The sensor 270 detects the intensity of an electric field created between the electrodes 230, that is, the intensity of an electric field applied to the non-freezing chamber 200. Therefore, if the electric field intensity is greater than an appropriate level, the electrodes 230 are separated further, while if the electric field intensity is smaller than an appropriate level, the electrodes 230 may be brought closer to each other.

[50] FIG. 6 is a flow chart describing a method for controlling a supercooling apparatus having electrodes arranged at an adjustable spacing between them, in accordance with a first embodiment of the present invention, a supercooling apparatus includes an outer casing 220; a storage container 210; a sensor 270 positioned in the outer casing 220, for detecting size of the storage container 210; electrodes 230; electrode panels 236 having the electrodes attached thereto and moving inside the outer casing 220; a motor 234b and a motor 234 for moving the electrode panels 236; and a controller (not shown) for controlling the operation of the electrodes 230, etc. A user selects one of storage containers 210 having various sizes according to the characteristics and size of an item to be stored in a non-freezing chamber 200. Next, he or she slides the storage container 210 into the outer casing 220. Then, in step Sl the sensor 270 detects size of the storage container 210 and sends the information to the controller (not shown). In step S2 the controller (not shown) adjusts the spacing between the electrodes 230 based on the size of the storage container 210. This is done by moving the electrode panels 236 with the attached electrodes 230 by the motor 234b. Provided that a uniform voltage is applied to the electrodes 230, the intensity of an electric field created between the electrodes, i.e. the intensity of an electric field applied to the non- freezing chamber 200, varies depending on the spacing between the electrodes 230. For instance, an expected intensity of an electric field for each item is calculated in advance to obtain a proper spacing between the electrodes 230. Then, the size of the storage container 210 where the item is to be kept is determined. In case the informations on storage containers designed to keep different kinds of items respectively are given to the user well in advance, he or she can choose a proper storage container 210 corresponding to the kind a target item. As aforementioned, the spacing between the electrodes 230 is automatically adjusted based on the size of the storage container 210 used. In other words, the spacing between the electrodes 230 can be adjusted according to the kind and size of a target item to be stored. This configuration and method are advantageous in that it is possible to control the intensity of an electric field applied to the non-freezing chamber 200, without changing a voltage level to be applied to the electrodes 230 from the power supply.

[51] FIG. 7 is a flow chart describing a method for controlling a supercooling apparatus having electrodes arranged at an adjustable spacing between them, in accordance with a second embodiment of the present invention. In step S 1 for detecting the size of a storage container 210, it is first decided whether the storage container 210 is placed in an outer casing 220 (Pl), and the size of the storage container 210 is then detected (P2). In step S2, the spacing between electrodes 230 is adjusted based on the size of the storage container 210.

[52] FIG. 8 is a flow chart describing a method for controlling a supercooling apparatus having electrodes arranged at an adjustable spacing between them, in accordance with a third embodiment of the present invention. When a user inserts a storage container 210 into an outer casing 220, a sensor, in step Sl, detects size of the storage container 210. In step S2 the spacing between electrodes 230 is adjusted based the size of the storage container 210. In this manner, the gap between the storage container 210 and each electrode 230 can be controlled to fall within a predetermined range. As discussed earlier, the intensity of an electric field created between the electrodes 230 varies depending on the spacing between the electrodes 230. In step S3 the sensor 270 detects the intensity of an electric field. If the detected electric field intensity is outside the range for an appropriate intensity, a voltage level to be applied to the electrodes 230 is then regulated in step S4. For example, when the electric field intensity increases too high because of the narrower distance between the electrodes 230, corona discharge is likely to occur between the electrodes 230. If this is the case, the applied voltage between the electrodes 230 needs to be lowered to prevent the corona discharge. On the other hand, if the electrodes 230 are located too far away from each other, the electric field intensity becomes extremely weak and it may become hard to have a stored item stay in the supercooled state. In this case, the supercooled state of a stored item can be maintained by increasing a voltage level to be applied to the electrodes 230. To this end, a power supply 232 supplying power to the electrodes 230 should be provided with a transformer to regulate the voltage.

[53] FIG. 9 is a flow chart describing a method for controlling a supercooling apparatus having electrodes arranged at an adjustable spacing between them, in accordance with a fourth embodiment of the present invention. The supercooling apparatus of this embodiment includes a sensor 270 that does not detect the intensity of an electric field but the distance between electrodes 230. Therefore, in step Sl the sensor 270 detects the distance between the electrodes 230, and a voltage level to be applied to the electrodes 230 is adjusted to a predetermined level according to the detected distance between the electrodes 230. When the electrodes 230 get closer to each other, a controller (not shown) causes a lower voltage to be applied to the electrodes 230. On the contrary, when the electrodes 230 become more distant from each other, the controller causes a higher voltage to be applied to the electrodes 230 to let stored items in a non-freezing chamber 200 stay in the supercooled state. The fourth embodiment is very useful especially when the distance between the electrodes 230 cannot be adjusted automatically by the controller but is done manually according to the size of a storage container 210 used.

[54] FIG. 10 is a flow chart describing a method for controlling a supercooling apparatus having electrodes arranged at an adjustable spacing between them, in accordance with a fifth embodiment of the present invention. According to the fifth embodiment, in step S 1 the intensity of an electric field applied to a non-freezing chamber 200 is detected, and in step S2 the distance between electrodes 230 is controlled accordingly. For instance, an extremely high electric field intensity is likely to cause corona discharge, or make water molecules in a stored item vibrate too much to get the item warmed up. When this occurs, the electric field intensity should be lowered by increasing the distance between the electrodes 230. On the other hand, if the electric field intensity is too low, items cannot be preserved in a supercooled state, or they can be frozen. When this occurs, the electric field intensity should be increased by decreasing the distance between the electrodes 230.

[55] FIG. 11 is a flow chart describing a method for controlling a supercooling apparatus having electrodes arranged at an adjustable spacing between them, in accordance with a sixth embodiment of the present invention. According to the sixth embodiment, in step S 1 the distance between electrodes 230 is adjusted, and in step S2 the voltage level to be applied to the electrodes is controlled correspondingly to a predetermined value given by the distance between the electrodes 230. For instance, different values of the electric field intensity depending on the distance between the electrodes 230 and the voltage level applied to the electrodes 230 may have been input to a controller in advance. Therefore, when a target electric field intensity is given, the distance between the electrodes 230 is adjusted and the voltage level to be applied to the electrodes is controlled next, until the current electric field intensity reaches the target value. Further, different levels of voltage to form an optimal electric field intensity depending on the distance between the electrodes 230 can be input to the controller as well. Therefore, the distance between the electrodes 230 is first adjusted, followed by the voltage level, to create the electric field with an optimal intensity value.

[56] The present invention has been described in detail with reference to the embodiments and the attached drawings. However, the scope of the present invention is not limited to the embodiments and the drawings, but defined by the appended claims.

Claims

[I] a supercooling apparatus, comprising: a refrigeration cycle; a non-freezing chamber to which chilled air from the refrigeration cycle is introduced, for storing an item; and a pair of electrodes for applying an electric field to the non-freezing chamber, the electrodes being arranged at an adjustable spacing therebetween according to characteristics of food to be stored. [2] The supercooling apparatus of claim 1, further comprising: a storage container being inserted into/taken out from the non-freezing chamber, for storing an item. [3] The supercooling apparatus of claim 2, wherein the spacing of the electrode pair is adjusted depending on size of the storage container. [4] The supercooling apparatus of claim 1, further comprising: a sensor for detecting the intensity of an electric field inside the non-freezing chamber. [5] The supercooling apparatus of claim 4, further comprising: a power supply for supplying a voltage level regulated depending on the intensity of an electric field. [6] The supercooling apparatus of claim 1, further comprising: a means for detecting a distance between the electrodes. [7] The supercooling apparatus of claim 6, wherein the distance between the electrodes is adjusted to cause the intensity of an electric field to be applied to the storage container to fall within a predetermined range. [8] The supercooling apparatus of claim 1, further comprising: a resilient member for transmitting a resilient force to the electrodes to adjust the spacing between the electrodes. [9] The supercooling apparatus of claim 1, further comprising: a motor for adjusting the spacing between the pair of electrodes. [10] The supercooling apparatus of claim 9, further comprising: a power transmission member for transmitting a driving power of the motor.

[I I] A method for controlling a supercooling apparatus with a pair of electrodes arranged at an adjustable spacing therebetween, comprising; a first step for detecting size of a storage container positioned in a non-freezing chamber; and a second step for adjusting spacing between the electrodes. [12] The method of claim 11, wherein the first step includes: a first process of deciding whether the storage container is fully inserted; and a second process of detecting size of the container. [13] The method of claim 11 , further comprising: a third step for detecting an electric field intensity being applied to the storage container; and a fourth step for regulating a voltage level being applied to the electrodes. [14] A method for controlling a supercooling apparatus with a pair of electrodes arranged at an adjustable spacing therebetween, comprising; a first step for detecting a distance between the electrodes; and a second step for regulating a voltage level being applied to the electrodes. [15] A method for controlling a supercooling apparatus with a pair of electrodes arranged at an adjustable spacing therebetween, comprising; a first step for detecting an electric field intensity being applied to non-freezing chamber; and a second step for adjusting a distance between the electrodes. [16] A method for controlling a supercooling apparatus with a pair of electrodes arranged at an adjustable spacing therebetween, comprising; a first step for adjusting a distance between the electrodes; and a second step for regulating a voltage level being applied to the electrodes.