Refrigerator, permanent magnet sheet for refrigerator and preparation method of permanent magnet sheet

Abstract

The invention provides a refrigerator, a permanent magnet sheet for the refrigerator and a preparation method of the permanent magnet sheet. The permanent magnet piece is used for being arranged in a refrigeration chamber of the refrigerator so as to generate a magnetic field in the refrigeration chamber, and the permanent magnet piece is configured in the mode that the intensity attenuation rate of the magnetic field intensity generated in the refrigeration chamber is smaller than or equal to 10% under the condition that the refrigeration chamber operates at the lowest temperature. The intensity attenuation rate is the ratio of the magnetic field intensity quantity reduced by the permanent magnet sheets relative to the initial magnetic field intensity generated in the refrigeration chamber to the initial magnetic field intensity. The ratio of the difference between the initial magnetic field intensity generated by the permanent magnet sheet in the refrigeration chamber and the stable magnetic field intensity finally achieved under the influence of the low-temperature environment of the refrigeration chamber and the initial magnetic field intensity is smaller than or equal to 10%, so that the difference between the magnetic field intensity finally generated by the permanent magnet sheet in the refrigeration chamber and the initial magnetic field intensity is within an allowable range; and the situation that the expected magnetic field fresh-keeping effect cannot be achieved due to the fact that the intensity attenuation rate of the permanent magnet pieces in the low-temperature environment is too large is avoided.

Description

Technical Field

[0001] This invention relates to the field of cold storage technology, and in particular to a refrigerator, a permanent magnet sheet for the refrigerator, and a method for preparing the permanent magnet sheet. Background Technology

[0002] Refrigerators, as a common household appliance, use low temperatures to store food, thereby extending its shelf life. While refrigerators extend the shelf life, the quality of food inevitably declines after low-temperature storage. However, ongoing research has revealed that magnetic fields have a beneficial effect on low-temperature food storage, not only further extending the shelf life but also helping to maintain freshness over a longer period. Therefore, the refrigerator industry is actively exploring the introduction of magnetic fields into refrigerators to achieve low-temperature storage under magnetic fields. Summary of the Invention

[0003] One object of the present invention is to provide a refrigerator that can achieve magnetic field preservation and improve the magnetic field preservation effect, a permanent magnet sheet for the refrigerator, and a method for preparing the permanent magnet sheet.

[0004] Specifically, the present invention provides a permanent magnet sheet for a refrigerator, wherein the permanent magnet sheet is disposed in the refrigerator's cooling compartment to generate a magnetic field in the cooling compartment. The permanent magnet sheet is configured such that the intensity of the magnetic field generated in the cooling compartment at the lowest operating temperature is less than or equal to 10%. The intensity attenuation rate is the ratio of the amount of magnetic field intensity reduction of the permanent magnet sheet compared to the initial magnetic field intensity generated in the cooling compartment to the initial magnetic field intensity. The initial magnetic field intensity is the magnetic field intensity generated in the cooling compartment when the permanent magnet sheet is first assembled in the cooling compartment.

[0005] Optionally, the permanent magnet is configured such that the dimensional shrinkage rate is less than or equal to 0.5% when the cooling chamber is operating at the lowest temperature. The dimensional shrinkage rate is the ratio of the reduction in the permanent magnet's volume relative to its initial volume to the initial volume.

[0006] Optionally, the surface of the permanent magnet sheet has a cured paint layer, which is formed by immersing the shaped permanent magnet sheet in a paint bath and then curing it.

[0007] Optionally, the thickness of the cured paint layer is greater than or equal to 0.3 mm and less than or equal to 0.7 mm.

[0008] Optionally, the permanent magnet sheet is a bonded permanent magnet, and the residual magnetic induction intensity of the permanent magnet sheet is greater than or equal to 60 millitrile and less than or equal to 350 millitrile.

[0009] Optionally, the intrinsic coercivity of the permanent magnet sheet is greater than or equal to 50 kA / m and less than or equal to 350 kA / m.

[0010] Optionally, the permanent magnet sheet may be composed of strontium ferrite, wherein the strontium ferrite accounts for more than or equal to 80% of the total weight of the permanent magnet sheet.

[0011] Optionally, the permanent magnet sheet is a sintered permanent magnet, and the residual magnetic induction intensity of the permanent magnet sheet is greater than or equal to 200 millitrile and less than or equal to 490 millitrile.

[0012] Optionally, the intrinsic coercivity of the permanent magnet sheet is greater than or equal to 200 kA / m and less than or equal to 450 kA / m.

[0013] Optionally, the permanent magnet sheet comprises ferric oxide and strontium carbonate, wherein ferric oxide accounts for 83% to 86% of the total weight of the permanent magnet sheet, and strontium carbonate accounts for 13% to 16% of the total weight of the permanent magnet sheet.

[0014] In another aspect of the present invention, a method for preparing a permanent magnet sheet is also provided, for producing a permanent magnet sheet according to any one of the above-mentioned methods, the method comprising:

[0015] The permanent magnet sheet shaping process is used to produce permanent magnet sheets of the required size.

[0016] The impregnation process involves placing the shaped permanent magnet sheet into a paint tank for impregnation, thereby forming a cured paint layer on the surface of the permanent magnet sheet.

[0017] The magnetization process involves applying a magnetic field to the permanent magnet sheet to make it magnetic.

[0018] Optionally, the process following the impregnation process includes:

[0019] The polishing process involves polishing the cured paint layer of the permanent magnet sheet to make the surface of the cured paint layer smooth and to ensure that the thickness of the cured paint layer is greater than or equal to 0.3 mm and less than or equal to 0.7 mm.

[0020] In another aspect of the invention, a refrigerator is also provided, comprising:

[0021] The cabinet contains a refrigerated compartment for storing food; and

[0022] At least one permanent magnet sheet according to any one of the above, the permanent magnet sheet being disposed in the refrigeration chamber to generate a magnetic field in the refrigeration chamber.

[0023] The permanent magnet sheet of the present invention is configured such that the magnetic field strength generated in the refrigeration room when operating at the lowest temperature has a strength attenuation rate of less than or equal to 10%. The strength attenuation rate is the ratio of the amount of magnetic field strength reduction of the permanent magnet sheet compared to the initial magnetic field strength generated in the refrigeration room to the initial magnetic field strength. In other words, the ratio of the difference between the initial magnetic field strength generated by the permanent magnet sheet in the refrigeration room and the final stable magnetic field strength reached under the influence of the low temperature environment of the refrigeration room to the initial magnetic field strength is less than or equal to 10%. This ensures that the difference between the final magnetic field strength generated by the permanent magnet sheet in the refrigeration room and the initial magnetic field strength is within an allowable range, avoiding the failure to achieve the expected magnetic field preservation effect due to excessive strength attenuation rate of the permanent magnet sheet in the low temperature environment. In other words, the permanent magnet sheet of this embodiment can more effectively and longer guarantee the preservation effect, that is, improve the magnetic field preservation effect.

[0024] Furthermore, the permanent magnet sheet of the present invention incorporates an impregnation process after molding, specifically by immersing the molded permanent magnet sheet in an impregnation tank to form a cured paint layer on its surface. This paint layer protects the permanent magnet sheet in the low-temperature environment of the refrigeration chamber, reducing the impact of the low temperature. Consequently, the magnetic field strength attenuation rate generated by the permanent magnet sheet in the refrigeration chamber, even when operating at the lowest temperature, is less than or equal to 10%. Simultaneously, the cured paint layer formed during the impregnation process also contributes to the structural stability of the permanent magnet sheet, resulting in a dimensional shrinkage rate of less than or equal to 0.5% when operating at the lowest temperature in the refrigeration chamber. Moreover, the cost increase from the impregnation process is relatively small.

[0025] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0026] The following sections will describe some specific embodiments of the invention in a detailed manner by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0027] Figure 1 This is a schematic diagram of a refrigerator according to an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of a permanent magnet sheet according to an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of a refrigerator according to another embodiment of the present invention;

[0030] Figure 4This is a schematic flowchart of a method for preparing a permanent magnet sheet according to an embodiment of the present invention;

[0031] Figure 5 This is a schematic flowchart of a method for preparing a permanent magnet sheet according to another embodiment of the present invention;

[0032] Explanation of reference numerals in the attached figures:

[0033] 100-Box body; 101-Refrigeration chamber; 200-Permanent magnet sheet; 210-Curing paint layer; 300-Storage container. Detailed Implementation

[0034] Those skilled in the art should understand that the embodiments described below are merely a part of the embodiments of the present invention, and not all of the embodiments of the present invention. These partial embodiments are intended to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Based on the embodiments provided by the present invention, all other embodiments obtained by those skilled in the art without creative effort should still fall within the scope of protection of the present invention.

[0035] The flowchart provided in this embodiment is not intended to indicate that the operations of the method will be performed in any particular order, or that all operations of the method are included in every case. Furthermore, the method may include additional operations. Within the scope of the technical concept provided by the method in this embodiment, additional variations can be made to the above method.

[0036] like Figure 1 As shown, in one embodiment, the refrigerator includes a cabinet 100 and two permanent magnet plates 200. The cabinet 100 has a refrigeration compartment 101 for storing food. The permanent magnet plates 200 are disposed in the refrigeration compartment 101 to generate a magnetic field within it. The permanent magnet plates 200 are configured such that, when the refrigeration compartment 101 is operating at its lowest temperature, the magnetic field strength generated by the permanent magnet plates 200 within the refrigeration compartment 101 decreases by less than or equal to 10%. This decrease is the ratio of the amount of magnetic field strength reduction by the permanent magnet plates 200 compared to the initial magnetic field strength generated within the refrigeration compartment 101 to the initial magnetic field strength. The initial magnetic field strength is the magnetic field strength generated within the refrigeration compartment 101 when the permanent magnet plates 200 are first assembled in the refrigeration compartment 101. Alternatively, it can be described as the magnetic field strength that the newly manufactured permanent magnet plates 200 can generate in the refrigeration compartment 101.

[0037] Reference Figure 1As shown, specifically, the cooling compartment 101 is a refrigerator compartment. The refrigerator also includes a storage container 300, which is placed in the cooling compartment 101 for storing food. Two permanent magnets 200 are located on the top and bottom sides of the storage container 300, respectively. The permanent magnets 200 can generate a magnetic field in the cooling compartment 101. Since the storage container 300 is located in the cooling compartment 101, when food is placed in the storage container 300, the magnetic field generated by the permanent magnets 200 can act on the food, thereby achieving low-temperature storage of the food under the magnetic field and improving the preservation effect.

[0038] Specifically, during food refrigeration, applying a magnetic field can reduce the supercooling of the food, meaning that the magnetic field allows the food to remain in a non-frozen state at a lower temperature. In other words, it lowers the refrigeration temperature, further reducing bacterial growth and helping to preserve the food's freshness. During freezing, the magnetic field restricts the free path of water molecules, causing the hydrogen bonds within water molecule clusters to break. This inhibits the growth of crystal nuclei within the food, leading to the formation of small ice crystals and reducing the damage caused by ice crystals to the food cells. Therefore, it helps reduce the loss of juices after thawing, thus minimizing nutrient loss and preserving the food's flavor.

[0039] Furthermore, the permanent magnet 200 is configured such that, when the cooling chamber 101 operates at its lowest temperature, the magnetic field strength generated by the permanent magnet 200 in the cooling chamber 101 exhibits a strength attenuation rate of less than or equal to 10%. This strength attenuation rate is the ratio of the amount of magnetic field strength reduction by the permanent magnet 200 compared to the initial magnetic field strength generated within the cooling chamber 101 to the initial magnetic field strength. Specifically, this means the ratio of the difference between the initial magnetic field strength generated by the permanent magnet 200 at the same location within the cooling chamber 101 and the final stable magnetic field strength to the initial magnetic field strength is less than or equal to 10%.

[0040] Specifically, for magnetic field preservation in refrigerators, a certain magnetic field strength is required to achieve the desired preservation effect. However, in the existing technology, those skilled in the art do not recognize that the permanent magnet sheet is in a low-temperature environment in the refrigerator. During use, the permanent magnet sheet is affected by the low temperature, and the magnetic field strength generated by the permanent magnet sheet in the cooling compartment will decrease to a certain extent. That is to say, although the permanent magnet sheet can initially generate a magnetic field strength that meets the requirements in the cooling compartment, after a period of use, the magnetic field strength generated by the permanent magnet sheet will decrease. The final stable magnetic field strength will be lower than the initial magnetic field strength generated by the permanent magnet sheet in the cooling compartment when it leaves the factory, resulting in the magnetic field preservation effect not meeting the expected requirements.

[0041] Therefore, in this application, the permanent magnet 200 is configured such that the magnetic field strength generated by the permanent magnet 200 in the cooling chamber 101 when the cooling chamber 101 is operating at the lowest temperature has a strength attenuation rate of less than or equal to 10%. In other words, from the initial start-up of the cooling chamber 101 where the permanent magnet 200 is located, even if it is always operating at the lowest temperature, the strength attenuation rate of the magnetic field strength generated by the permanent magnet 200 at the same position in the cooling chamber 101 is less than 10%. That is, the ratio of the amount of magnetic field strength reduction of the current magnetic field strength generated by the permanent magnet 200 at the same position in the cooling chamber 101 compared to the initial magnetic field strength to the initial magnetic field strength is less than or equal to 10%.

[0042] For example, the initial magnetic field strength generated by the permanent magnet 200 at a certain point in the cooling chamber 101 is 40 Gauss. After being used in a low-temperature environment for a period of time, the magnetic field strength generated by the permanent magnet 200 at the same location in the cooling chamber 101 eventually stabilizes at 38 Gauss. The magnetic field strength decay rate is (40 Gauss - 38 Gauss) / 40 Gauss, that is, the magnetic field strength decay rate is 5%.

[0043] By configuring the permanent magnet 200 such that the magnetic field strength generated in the refrigeration chamber 101 at its lowest operating temperature has a strength attenuation rate of less than or equal to 10%, and the strength attenuation rate is the ratio of the amount of magnetic field strength reduction of the permanent magnet 200 compared to the initial magnetic field strength generated in the refrigeration chamber 101 to the initial magnetic field strength, the difference between the initial magnetic field strength generated by the permanent magnet 200 in the refrigeration chamber 101 and the final stable magnetic field strength reached under the influence of the low temperature environment of the refrigeration chamber 101 is less than or equal to 10%. This ensures that the difference between the final magnetic field strength generated by the permanent magnet 200 in the refrigeration chamber 101 and the initial magnetic field strength is within an allowable range, avoiding the failure to achieve the expected magnetic field preservation effect due to excessive strength attenuation rate of the permanent magnet 200 in the low temperature environment. In other words, the permanent magnet 200 in this embodiment can more effectively and longer guarantee the preservation effect, thus improving the magnetic field preservation effect.

[0044] Reference Figure 1 As shown, the permanent magnet 200 is configured such that when the cooling chamber 101 is operating at the lowest temperature, the structural dimensional shrinkage rate is less than or equal to 0.5%, and the structural dimensional shrinkage rate is the ratio of the reduction in the permanent magnet 200 relative to its initial volume to the initial volume.

[0045] Specifically, the permanent magnet is in a low-temperature environment in the refrigerator. During use, the permanent magnet will shrink and deform due to the low temperature. In other words, after a period of use, the final stable volume of the permanent magnet will be lower than the initial volume when it left the factory. As a result, the magnetic field strength generated by the permanent magnet in the same position in the refrigeration compartment will also decrease.

[0046] Therefore, the permanent magnet 200 is configured such that the structural dimension shrinkage rate of the refrigeration chamber 101 is less than or equal to 0.5% when it is operating at the lowest temperature. In other words, the refrigeration chamber 101 where the permanent magnet 200 is located operates at the lowest temperature from the initial start-up of the refrigeration system, and the structural dimension shrinkage rate of the permanent magnet 200 is less than or equal to 0.5%, that is, the ratio of the volume reduction of the permanent magnet 200 compared to its initial volume to the initial volume is less than or equal to 0.5%.

[0047] For example, the initial volume of the permanent magnet sheet 200 is 120 cubic centimeters. After being used in a low-temperature environment for a period of time, the volume of the permanent magnet sheet 200 eventually stabilizes at 119.5 cubic centimeters. The structural size shrinkage rate is (120 cubic centimeters - 119.5 cubic centimeters) / 120 cubic centimeters, that is, the structural size shrinkage rate is 0.42%.

[0048] By configuring the permanent magnet sheet 200 such that its structural dimensional shrinkage rate is less than or equal to 0.5% when the refrigeration compartment 101 operates at its lowest temperature, the structural dimensional shrinkage rate is determined by the ratio of the reduction in the permanent magnet sheet 200's volume compared to its initial volume to its initial volume. In other words, the ratio of the difference between the initial volume of the permanent magnet sheet 200 and its final volume under the influence of the low-temperature environment of the refrigeration compartment 101 to the initial volume is less than or equal to 0.5%. This minimizes the difference between the final volume and the initial volume, preventing excessive changes in magnetic field strength at the same location in the refrigeration compartment 101 due to excessive structural dimensional shrinkage of the permanent magnet sheet 200 under low-temperature conditions, thus ensuring the refrigerator's magnetic field preservation effect. Furthermore, this also helps prevent problems such as cracking of the permanent magnet sheet due to excessive structural dimensional shrinkage.

[0049] like Figure 2 As shown, the surface of the permanent magnet sheet 200 has a cured paint layer 210, which is formed by immersing the shaped permanent magnet sheet 200 in a paint bath and then curing it. Specifically, during the production process of the permanent magnet sheet 200, after obtaining the shaped permanent magnet sheet 200 of the required size, the permanent magnet sheet 200 is immersed in a paint bath to form a cured paint layer on its surface. The cured paint layer 210 covers the surface of the permanent magnet sheet 200.

[0050] By providing a cured paint layer 210 to the permanent magnet sheet 200, when the permanent magnet sheet 200 is in the low-temperature environment of the cooling chamber 101, the cured paint layer 210 on the surface of the permanent magnet sheet 200 can protect the permanent magnet sheet 200, reducing the impact of the low-temperature environment on the permanent magnet sheet 200. This ensures that the magnetic field strength generated by the permanent magnet sheet 200 in the cooling chamber 101, when operating at the lowest temperature, has a strength attenuation rate of less than or equal to 10%. Simultaneously, the cured paint layer 210 also helps to make the structure of the permanent magnet sheet 200 more stable, resulting in a structural dimensional shrinkage rate of less than or equal to 0.5% when the permanent magnet sheet 200 is operating at the lowest temperature in the cooling chamber 101.

[0051] Reference Figure 2 As shown, the thickness of the cured paint layer 210 is greater than or equal to 0.3 mm and less than or equal to 0.7 mm. For example, it can be 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, or 0.7 mm, etc. The thickness of the cured paint layer 210, greater than or equal to 0.3 mm and less than or equal to 0.7 mm, ensures the protective effect of the cured paint layer 210 while avoiding an excessively thick permanent magnet sheet 200, allowing for more flexible selection of the installation position of the permanent magnet sheet 200 in the cooling chamber 101.

[0052] like Figure 3 As shown, in another embodiment, the refrigerator includes a cabinet 100 and two permanent magnet plates 200. The cabinet 100 contains a refrigeration compartment 101 for storing food. The permanent magnet plates 200 are disposed in the refrigeration compartment 101 to generate a magnetic field within it. The permanent magnet plates 200 are configured such that, when the refrigeration compartment 101 operates at its lowest temperature, the magnetic field strength generated by the permanent magnet plates 200 in the refrigeration compartment 101 decreases by less than or equal to 10%, where the decrease is the ratio of the amount of magnetic field strength reduced by the permanent magnet plates 200 compared to the initial magnetic field strength generated within the refrigeration compartment 101 to the initial magnetic field strength. Specifically, in this embodiment, the refrigeration compartment 101 is a freezer compartment.

[0053] In addition, in this embodiment, the permanent magnet sheet 200 is configured such that the structural dimensional shrinkage rate is less than or equal to 0.5% when the cooling chamber 101 is operating at the lowest temperature.

[0054] The technical effects of this embodiment are as described above and will not be repeated here.

[0055] It should be noted that the refrigerator can have one, two, three, or more cooling compartments, and the function of each compartment can be refrigeration, freezing, or variable temperature. When multiple cooling compartments are provided, they can be arranged vertically or horizontally. Those skilled in the art can configure the specific number, function, and layout of the compartments according to their needs.

[0056] It should also be noted that refrigerators can be equipped with storage containers for storing food, or food can be placed using shelves set in the refrigeration compartment, or food can be placed directly using permanent magnets.

[0057] Additionally, it should be noted that a single permanent magnet can be installed in a refrigeration compartment, or multiple permanent magnets can be installed. When multiple refrigeration compartments are configured, permanent magnets can be installed in only some of the compartments, or in all of them.

[0058] Specifically, in one embodiment, the permanent magnet sheet is a bonded permanent magnet, and the remanent magnetic induction intensity of the permanent magnet sheet is greater than or equal to 60 millitriles and less than or equal to 350 millitriles. This ensures that when used in a refrigeration room, the magnetic induction intensity at all points within the refrigeration room meets the requirements. Preferably, it is greater than or equal to 240 millitriles and less than or equal to 270 millitriles.

[0059] Furthermore, the intrinsic coercivity of the permanent magnet sheet is greater than or equal to 50 kA / m and less than or equal to 350 kA / m, preferably greater than or equal to 190 kA / m and less than or equal to 240 kA / m. By ensuring that the intrinsic coercivity of the permanent magnet sheet is greater than or equal to 50 kA / m and less than or equal to 350 kA / m, the permanent magnet sheet is less susceptible to external interference, thereby reducing the strength attenuation rate of the permanent magnet sheet in the refrigeration chamber and ensuring that the strength attenuation rate is less than or equal to 10%.

[0060] In addition, the coercivity of the permanent magnet sheet is greater than or equal to 50 kA / m and less than or equal to 260 kA / m, preferably greater than or equal to 150 kA / m and less than or equal to 180 kA / m. The maximum magnetic energy product of the permanent magnet sheet is greater than or equal to 0.8 kJ / m and less than or equal to 25 kJ / m, preferably greater than or equal to 11 kJ / m and less than or equal to 14 kJ / m.

[0061] The above configuration parameters ensure that the magnetic induction intensity of the permanent magnet sheet meets the requirements for magnetic field preservation and is not easily affected by external interference, thereby reducing the intensity attenuation rate of the permanent magnet sheet.

[0062] In addition, the permanent magnet sheet is a bonded permanent magnet. The composition of the permanent magnet sheet includes strontium ferrite, and the proportion of strontium ferrite in the total weight of the permanent magnet sheet is greater than or equal to 80%. This helps to ensure that the various configuration parameters of the bonded permanent magnet sheet meet the above requirements, thereby ensuring that the strength attenuation rate of the bonded permanent magnet sheet is within the allowable range.

[0063] Specifically, in one embodiment, the permanent magnet sheet is a sintered permanent magnet with a remanent magnetic induction intensity greater than or equal to 200 millitriles and less than or equal to 490 millitriles, thereby ensuring that the magnetic induction intensity at all points in the refrigeration room meets the requirements when used in a refrigeration room. Preferably, it is greater than or equal to 370 millitriles and less than or equal to 390 millitriles.

[0064] Furthermore, the intrinsic coercivity of the permanent magnet sheet is greater than or equal to 200 kA / m and less than or equal to 450 kA / m, preferably greater than or equal to 310 kA / m and less than or equal to 330 kA / m. By ensuring that the intrinsic coercivity of the permanent magnet sheet is greater than or equal to 200 kA / m and less than or equal to 450 kA / m, the permanent magnet sheet is less susceptible to external interference, thereby reducing the strength attenuation rate of the permanent magnet sheet in the refrigeration chamber and ensuring that the strength attenuation rate is less than or equal to 10%.

[0065] In addition, the coercivity of the permanent magnet sheet is greater than or equal to 120 kA / m and less than or equal to 360 kA / m, preferably greater than or equal to 260 kA / m and less than or equal to 290 kA / m. The maximum magnetic energy product of the permanent magnet sheet is greater than or equal to 6.4 kJ / m³ and less than or equal to 45 kJ / m³, preferably greater than or equal to 25 kJ / m³ and less than or equal to 29 kJ / m³.

[0066] The above configuration parameters ensure that the magnetic induction intensity of the permanent magnet sheet meets the requirements for magnetic field preservation and is not easily affected by external interference, thereby reducing the strength decay rate of the permanent magnet sheet. It should be noted that because sintered permanent magnet sheets decay more easily than bonded permanent magnet sheets, the relevant parameters need to be higher.

[0067] Furthermore, the permanent magnet sheet is a sintered permanent magnet, and its composition includes ferric oxide and strontium carbonate. Ferric oxide accounts for 83% to 86% of the total weight of the permanent magnet sheet, while strontium carbonate accounts for 13% to 16% of the total weight. This helps ensure that the configuration parameters of the sintered permanent magnet sheet meet the aforementioned requirements, thereby ensuring that the strength attenuation rate of the sintered permanent magnet sheet is within the allowable range.

[0068] like Figure 4 As shown, in one embodiment, the method for preparing a permanent magnet sheet generally includes:

[0069] Step S401, permanent magnet sheet shaping process. Used to produce permanent magnet sheets of the required size.

[0070] For the permanent magnet sheet being a bonded permanent magnet, this step includes intensively mixing and pulverizing the raw materials to obtain a material mixture, then calendering the initially obtained block material mixture to obtain a sheet structure of the required thickness. The obtained sheet structure is then cut to obtain the final product permanent magnet sheet of the required size, i.e., the shaped permanent magnet sheet.

[0071] For sintered permanent magnet sheets, this step includes granulating the raw materials, which involves mixing the raw materials with auxiliary materials such as binders and then shaping them into particles of a specific shape and size using molding equipment. The particles are then pre-fired to remove the auxiliary agents introduced during granulation. The pre-fired material is then crushed to obtain finer powder particles. These particles are then oriented and shaped, typically by applying external force to align the crystals or magnetic domains within the material in a specific direction. The oriented and shaped powder particles are then sintered at high temperature, allowing diffusion bonding between the particles to form a preliminary sheet-like structure. This preliminary sheet-like structure is then processed to obtain the final product—the shaped permanent magnet sheet—of the required size.

[0072] Step S402, the varnish dipping process. Specifically, the varnish dipping process involves immersing the formed permanent magnet sheet in a varnish bath, removing it after dipping, and then baking it in a constant temperature oven at 50℃~200℃ for 3-7 hours to cure it. In other words, baking the permanent magnet sheet in a constant temperature oven at 50℃ to 200℃ (inclusive) for 3 to 7 hours (inclusive) allows a cured varnish layer to form on the surface of the permanent magnet sheet. That is, by immersing the entire permanent magnet sheet in a varnish bath, the varnish coats the surface of the permanent magnet sheet, and after curing, a cured varnish layer is formed on the surface of the permanent magnet sheet.

[0073] Step S403, magnetization process. The magnetization process involves applying a magnetic field to the permanent magnet sheet to make it magnetic. Specifically, this means applying an external magnetic field to the permanent magnet sheet for a certain period of time to make it magnetic, that is, to obtain residual magnetic induction intensity, so that the permanent magnet sheet can generate a magnetic field.

[0074] The permanent magnet sheet is a bonded permanent magnet. After the magnetization process, the residual magnetic induction intensity of the permanent magnet sheet is greater than or equal to 60 millitriles and less than or equal to 350 millitriles, thus ensuring that the magnetic induction intensity at all points in the refrigeration room meets the requirements when used in the refrigeration room. Preferably, it is greater than or equal to 240 millitriles and less than or equal to 270 millitriles.

[0075] Furthermore, the intrinsic coercivity of the prepared permanent magnet sheet is greater than or equal to 50 kA / m and less than or equal to 350 kA / m, preferably greater than or equal to 190 kA / m and less than or equal to 240 kA / m. The coercivity of the permanent magnet sheet is greater than or equal to 50 kA / m and less than or equal to 260 kA / m, preferably greater than or equal to 150 kA / m and less than or equal to 180 kA / m. The maximum magnetic energy product of the permanent magnet sheet is greater than or equal to 0.8 kJ / m³ and less than or equal to 25 kJ / m³, preferably greater than or equal to 11 kJ / m³ and less than or equal to 14 kJ / m³.

[0076] The permanent magnet sheet is a sintered permanent magnet. After the magnetization process, the residual magnetic induction intensity of the permanent magnet sheet is greater than or equal to 200 millitriles and less than or equal to 490 millitriles, thus ensuring that the magnetic induction intensity at all points in the refrigeration room meets the requirements when used in the refrigeration room. Preferably, it is greater than or equal to 370 millitriles and less than or equal to 390 millitriles.

[0077] Furthermore, the intrinsic coercivity of the prepared permanent magnet sheet is greater than or equal to 200 kA / m and less than or equal to 450 kA / m, preferably greater than or equal to 310 kA / m and less than or equal to 330 kA / m. The coercivity of the permanent magnet sheet is greater than or equal to 120 kA / m and less than or equal to 360 kA / m, preferably greater than or equal to 260 kA / m and less than or equal to 290 kA / m. The maximum magnetic energy product of the permanent magnet sheet is greater than or equal to 6.4 kJ / m³ and less than or equal to 45 kJ / m³, preferably greater than or equal to 25 kJ / m³ and less than or equal to 29 kJ / m³.

[0078] By adding an impregnation process after the permanent magnet sheet is formed—that is, by immersing the formed permanent magnet sheet in an impregnation tank—a cured paint layer is formed on the surface of the permanent magnet sheet. In this way, when the permanent magnet sheet is in the low-temperature environment of the cooling chamber, the paint layer on the surface of the permanent magnet sheet can protect the permanent magnet sheet, reducing the impact of the low-temperature environment on the permanent magnet sheet. Therefore, the magnetic field strength attenuation rate generated by the permanent magnet sheet in the cooling chamber 101 when operating at the lowest temperature is less than or equal to 10%. At the same time, the cured paint layer formed by the impregnation process also helps to make the permanent magnet sheet structure more stable, resulting in a structural dimensional shrinkage rate of less than or equal to 0.5% when the permanent magnet sheet operates at the lowest temperature in the cooling chamber. Furthermore, the cost of the impregnation process is relatively small.

[0079] like Figure 5 As shown, in one embodiment, the method for preparing the permanent magnet sheet includes a polishing process after the impregnation process. The polishing process involves polishing the cured paint layer of the permanent magnet sheet to make the surface of the cured paint layer smooth. The thickness of the cured paint layer is greater than or equal to 0.3 mm and less than or equal to 0.7 mm.

[0080] Specifically, the preparation process of permanent magnet sheets generally includes:

[0081] Step S501, permanent magnet sheet shaping process. Specifically, this involves obtaining a permanent magnet sheet of the required size.

[0082] Step S502, the varnish dipping process. Specifically, the varnish dipping process involves immersing the formed permanent magnet sheet in a varnish bath, removing it after dipping, and then baking it in a constant temperature oven at 50℃~200℃ for 3-7 hours to cure it. In other words, baking the permanent magnet sheet in a constant temperature oven at 50℃ to 200℃ (inclusive) for 3 to 7 hours (inclusive) allows a cured varnish layer to form on the surface of the permanent magnet sheet. That is, by immersing the entire permanent magnet sheet in a varnish bath, the varnish coats the surface of the permanent magnet sheet, and after curing, a cured varnish layer is formed on the surface of the permanent magnet sheet.

[0083] Step S503, Grinding process. Specifically, this involves grinding the cured paint layer of the permanent magnet sheet to make the surface of the cured paint layer smoother. In addition, after the grinding process, ensure that the thickness of the cured paint layer of the permanent magnet sheet is greater than or equal to 0.3 mm and less than or equal to 0.7 mm.

[0084] Step S504, magnetization process. The magnetization process involves applying a magnetic field to the permanent magnet sheet to make it magnetic. Specifically, this means applying an external magnetic field to the permanent magnet sheet for a certain period of time to make it magnetic, that is, to obtain residual magnetic induction intensity, so that the permanent magnet sheet can generate a magnetic field.

[0085] By sanding the cured paint layer after the impregnation process, the surface of the cured paint layer becomes smooth, which facilitates installation in the refrigeration room. Furthermore, after the sanding process, the thickness of the cured paint layer on the permanent magnet sheet is ensured to be greater than or equal to 0.3 mm and less than or equal to 0.7 mm. This ensures the protective effect of the cured paint layer while preventing the permanent magnet sheet from becoming too thick, allowing for more flexible selection of its installation location in the refrigeration room.

[0086] Therefore, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and construed as covering all such other variations or modifications.

Claims

1. A permanent magnet sheet for use in a refrigerator, wherein, The permanent magnet is used to be disposed in the refrigeration compartment of the refrigerator to generate a magnetic field in the refrigeration compartment. The permanent magnet is configured such that the intensity attenuation rate of the magnetic field generated in the refrigeration compartment is less than or equal to 10% when the refrigeration compartment is operating at the lowest temperature.

2. The permanent magnet sheet for a refrigerator according to claim 1, wherein, The permanent magnet is configured such that its structural dimensional shrinkage rate is less than or equal to 0.5% when the cooling chamber is operating at the lowest temperature.

3. The permanent magnet sheet for a refrigerator according to claim 2, wherein, The surface of the permanent magnet sheet has a cured paint layer, which is formed by immersing the shaped permanent magnet sheet in a paint bath and then curing it.

4. The permanent magnet sheet for a refrigerator according to claim 3, wherein, The thickness of the cured paint layer is greater than or equal to 0.3 mm and less than or equal to 0.7 mm.

5. The permanent magnet sheet for a refrigerator according to claim 1, wherein, The permanent magnet sheet is a bonded permanent magnet, and the residual magnetic induction intensity of the permanent magnet sheet is greater than or equal to 60 millitrile and less than or equal to 350 millitrile.

6. The permanent magnet sheet for a refrigerator according to claim 5, wherein, The intrinsic coercivity of the permanent magnet sheet is greater than or equal to 50 kA / m and less than or equal to 350 kA / m.

7. The permanent magnet sheet for a refrigerator according to claim 5, wherein, The permanent magnet sheet is composed of strontium ferrite, and the strontium ferrite accounts for more than or equal to 80% of the total weight of the permanent magnet sheet.

8. The permanent magnet sheet for a refrigerator according to claim 1, wherein, The permanent magnet sheet is a sintered permanent magnet, and the residual magnetic induction intensity of the permanent magnet sheet is greater than or equal to 200 millitrile and less than or equal to 490 millitrile.

9. The permanent magnet sheet for a refrigerator according to claim 8, wherein, The intrinsic coercivity of the permanent magnet sheet is greater than or equal to 200 kA / m and less than or equal to 450 kA / m.

10. The permanent magnet sheet for a refrigerator according to claim 8, wherein, The permanent magnet sheet comprises ferric oxide and strontium carbonate, wherein the ferric oxide accounts for 83% to 86% of the total weight of the permanent magnet sheet, and the strontium carbonate accounts for 13% to 16% of the total weight of the permanent magnet sheet.

11. A method for preparing a permanent magnet sheet, used to produce the permanent magnet sheet according to any one of claims 1 to 10, the method comprising: The permanent magnet sheet shaping process is used to produce permanent magnet sheets of the required size. The impregnation process involves placing the shaped permanent magnet sheet into a paint tank for impregnation, thereby forming a cured paint layer on the surface of the permanent magnet sheet. The magnetization process involves applying a magnetic field to the permanent magnet sheet to make it magnetic.

12. The method for preparing a permanent magnet sheet according to claim 11, wherein the impregnation process is followed by: The polishing process involves polishing the cured paint layer of the permanent magnet sheet to make the surface of the cured paint layer of the permanent magnet sheet smooth, and to make the thickness of the cured paint layer greater than or equal to 0.3 mm and less than or equal to 0.7 mm.

13. A refrigerator, comprising: The box contains a refrigerated compartment for storing food ingredients; and At least one permanent magnet sheet according to any one of claims 1 to 10, the permanent magnet sheet being disposed in the refrigeration chamber to generate a magnetic field in the refrigeration chamber.

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