KR102373094B1 - Electric range - Google Patents

Abstract

The present invention relates to an electric range of induction heating type. The present invention includes a coil, a metal plate disposed under the coil to overlap the coil, and a magnetic field shielding sheet disposed between the coil and the metal plate to shield at least a portion of a magnetic field formed in the coil, The magnetic field shielding sheet includes an alloy composed of at least one of B, C, N, Si, P, Co, Cu, Zr, Nb and Ta and Fe, wherein at least a portion of the alloy is in a crystallized state An electric stove is provided. Since the magnetic field shielding sheet according to the present invention has a higher saturation magnetic flux density than that of a conventional shielding agent, when the magnetic field shielding sheet is used, an electric range capable of outputting higher than that of a conventional electric range can be implemented.

Description

electric range {ELECTRIC RANGE}

The present invention relates to an electric range of induction heating type.

Induction heating is a method of heating a metal object using electromagnetic induction. When a current flows through the coil, a magnetic field is formed, which causes eddy currents to be generated in the metal located around the coil. At this time, Joule heating generated by the resistance of the metal increases the temperature.

The electric range has a disadvantage that a dedicated container must be used, but has the advantage that no harmful gas is generated, it is safe from fire, and there is no risk of burns. In addition, compared with a gas range that burns and heats gas, its efficiency is significantly higher, and therefore, the demand for the electric range is increasing.

However, the magnetic field generated in the electric range may affect not only the object to be heated, but also the conductors around the electric range. That is, the magnetic field generated in the electric range may heat a conductor other than the object to be heated. This is not only a factor of lowering the stability of the electric range, but also a factor of reducing the efficiency of the electric range.

In general, in the electric range, a shielding sheet made of Mn-Zn ferrite is used to shield the magnetic field. However, since the material has a low saturation magnetic flux density, it is necessary to increase the thickness of the shielding sheet in order to increase the output of the electric range. As described above, as the output of the electric range increases, there is a problem in that the weight and thickness of the electric range increase.

An object of the present invention is to provide an electric range having an output superior to that of a conventional electric range of an induction heating method in order to solve the above problem.

In addition, an object of the present invention is to provide an electric range that is lighter than the electric range of the conventional induction heating method and has a thinner thickness.

In addition, an object of the present invention is to provide an electric range having better efficiency than the conventional electric range of the induction heating method.

In order to achieve the above object, the present invention uses a magnetic field shielding sheet having a high shielding ability and low shielding loss in configuring an electric range of an induction heating method.

In a specific embodiment, the present invention provides a coil, a metal plate disposed under the coil so as to overlap the coil, and a magnetic field shield disposed between the coil and the metal plate to shield at least a portion of a magnetic field formed in the coil a sheet, wherein the magnetic field shielding sheet includes an alloy composed of Fe and at least one of B, C, N, Si, P, Co, Cu, Zr, Nb and Ta, and at least a portion of the alloy is crystallized It provides an electric range, characterized in that the state.

Here, the alloy constituting the magnetic field shielding sheet has a higher saturation magnetic flux density and proper magnetic permeability than conventional shielding agents. Through this, it becomes possible to increase the output of the electric range. In addition, since the magnetic field shielding sheet is formed thinner than a conventional shielding agent having the same shielding performance, it becomes possible to reduce the thickness of the electric range and to reduce the weight.

In an embodiment, the magnetic field shielding sheet may include an adhesive layer and an adhesive layer disposed on the adhesive layer, a shielding layer made of the alloy and a protective layer disposed on the shielding layer, and a plurality of metal pieces made of an alloy can be made with

Here, the shielding layer is composed of a plurality of metal pieces, and the shielding loss in the shielding layer is minimized by partially crystallizing an alloy constituting the shielding layer.

In one embodiment, the present invention limits the composition of the magnetic field shielding sheet, the saturation magnetic flux density, the magnetic permeability, the crystal grain size of the alloy constituting the magnetic field shielding sheet, and the crystallized area to provide an electric range that can have maximum output and efficiency. make up

In one embodiment, the present invention may include a magnetic field shielding sheet made of a plurality of shielding layers. Through this, it is possible to improve the performance of the magnetic shielding sheet.

In addition, the present invention includes a coil, a magnetic field shielding sheet disposed under the coil so as to overlap the coil, and having a metal alloy, a ferrite sintered body disposed under the magnetic field shielding sheet, and a metal plate disposed under the ferrite sintered body, and , At least a portion of the alloy provided in the magnetic field shielding sheet provides an electric range, characterized in that the crystallized state.

Since the magnetic field shielding sheet according to the present invention has a higher saturation magnetic flux density than that of a conventional shielding agent, it is possible to increase the external magnetic field strength applied to the shielding sheet. Accordingly, it is possible to implement an electric range capable of outputting a higher output than the conventional electric range.

In addition, since the magnetic field shielding sheet according to the present invention has less hysteresis loss and eddy current loss due to shielding than conventional shielding agents, when the magnetic field shielding sheet is used, an electric range having higher efficiency than a conventional electric range can be implemented.

In addition, since the magnetic field shielding sheet according to the present invention has excellent shielding performance even at a thickness thinner than that of a conventional shielding agent, using the magnetic shielding sheet, an electric range having a lighter and thinner thickness than a conventional electric range can be realized.

1 is a graph showing a hysteresis curve of a masking agent.
2 is a perspective view of an electric range according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view taken along line A-A' in FIG. 2;
FIG. 4 is a cross-sectional view taken along line A-A' of FIG. 2 , and FIG. 4 is a cross-sectional view taken along line A-A' after placing an external object in the electric range described in FIG. 2 .
5 is a cross-sectional view of a magnetic field shielding sheet according to an embodiment of the present invention.
6 is a graph showing the output of the electric range according to the coil current strength.
7 is a graph showing the coil temperature according to the operating time of the electric range.
8 is a cross-sectional view of a magnetic field shielding sheet including a plurality of shielding layers.
9 is a graph showing the results of differential scanning calorimetry for an amorphous metal.
10 is a graph showing the results of X-ray diffraction analysis of the amorphous metal and the amorphous metal after heat treatment.
11 is a graph illustrating a change in magnetic flux density according to an external magnetic field when a shielding agent is formed by using a partial nanocrystal material and a ferrite material in combination.
12A to 12B are exploded views of an electric range according to the present invention.

Hereinafter, the embodiments disclosed in the present specification will be described in detail with reference to the accompanying drawings, but the same or similar components are assigned the same reference numbers regardless of reference numerals, and redundant description thereof will be omitted. In addition, in describing the embodiments disclosed in the present specification, if it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed in this specification, the detailed description thereof will be omitted. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and the technical idea disclosed herein is not limited by the accompanying drawings, and all changes included in the spirit and scope of the present invention , should be understood to include equivalents or substitutes.

Terms including an ordinal number such as 1st, 2nd, etc. may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

The singular expression includes the plural expression unless the context clearly dictates otherwise.

In the present application, terms such as “comprises” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

The electric range according to the present invention is an electric range that heats a conductor by an induction heating method. When a current flows through the coil, a magnetic field is generated around the coil, and the magnetic field causes an eddy current loss in a conductor positioned adjacent to the coil. Due to the resistance of the conductor, heat loss occurs in the conductor when the eddy current is formed. The electric range according to the present invention causes the conductor to heat up by using the above-described eddy current loss.

Here, the conductor may be a container dedicated to the electric range. In general, the dedicated container is disposed above the coil, and is heated under the influence of a magnetic field formed above the coil. On the other hand, various parts for constituting the electric range may be disposed under the coil. The magnetic field generated in the coil is formed not only on the upper side of the coil, but also on the lower side of the coil.

In the conventional induction heating method, a shielding layer for shielding a magnetic field formed below the coil is formed in the electric range. Specifically, referring to the hysteresis curve shown in FIG. 1 , the magnetic flux density of the shielding first increases as the strength of the magnetic field (external magnetic field) formed around the coil increases. Through this, the shielding first performs a shielding function, and in particular, the shielding efficiency is the highest in the section 10 in which the magnetic flux density linearly increases with respect to the external magnetic field.

Referring to FIG. 1 , when the intensity of the external magnetic field exceeds a certain level, the linear section 10 is deviated. When the shielding layer is saturated (11), the magnetic properties of the shielding layer change, which causes the electric range to malfunction. Therefore, the strength of the external magnetic field should be increased only until the shielding layer is saturated, and preferably, it should only be increased to a range in which the hysteresis curve of the shielding layer is linear.

Meanwhile, comparing the hysteresis curves of the shielding agents 1 and 2 shown in FIG. 1 , the linear section 20 of the shielding second having a high saturation magnetic flux density is wider than that of the shielding agent 1, and the external magnetic field in which the shielding layer reaches the saturation 21 The intensity is greater than that of masking agent 1.

For the above reasons, the conventional electric range using a shielding layer having a low saturation magnetic flux density cannot increase the strength of the magnetic field generated from the coil to a certain level or more, and thus, increasing the output of the electric range is limited.

On the other hand, in order to improve the output of the electric range, there is a method of increasing the thickness of the shielding layer, but in this case, the efficiency of the electric range is decreased, the thickness is increased, and there are disadvantages in that the weight of the product is increased.

The present invention provides an electric range capable of heating a conductor with high output and efficiency. In addition, the present invention provides an electric range having a higher output and a thinner thickness than a conventional electric range.

Specifically, since the electric range according to the present invention heats an external object (conductor) using the magnetic field generated from the coil, the coil generating the magnetic field and the magnetic field generated from the coil are prevented from affecting other conductors other than the external object A magnetic shielding sheet is provided. Hereinafter, with reference to the accompanying drawings, the electric range for achieving the above object and the role of the magnetic field shielding sheet included in the electric range will be described in detail.

Figure 2 is a perspective view showing an electric range according to an embodiment of the present invention, Figure 3 is a cross-sectional view taken along the line A-A' of Figure 2, Figure 4 is an external object placed in the electric range described in Figure 2 It is a cross-sectional view taken along line A-A'.

Referring to FIG. 2 , the electric range 100 according to the present invention includes at least one heating unit 150a to 150c. A coil is disposed at a position corresponding to the heating unit. The external object is heated with high efficiency when it is placed in a position corresponding to the heating part.

Referring to FIG. 3 , a coil 110 may be disposed at a position corresponding to the heating unit 150a. In the present specification, it is defined that the coil 110 is disposed below the heating unit 150a, and the positions of each component are defined based on this. Here, the upper direction opposite to the lower direction may be defined as the z direction of FIG. 2 , that is, a direction perpendicular to the floor on which the electric range 100 is disposed.

Specifically, the electric range 100 according to the present invention includes a magnetic field shielding sheet 120 and a metal plate 130 . Here, the magnetic field shielding sheet 120 is disposed under the coil 110 , and the metal plate 130 is disposed under the magnetic field shielding sheet 120 , and overlaps at least a portion of the magnetic field shielding sheet 120 .

As described above, the electric range 100 described in FIG. 3 includes a metal plate 130 , a magnetic field shielding sheet 120 , and a coil 110 that are sequentially arranged in an upper direction of the electric range.

Additionally, the electric range 100 according to the present invention may include a heat dissipation fan 140 for dissipating heat and a case 150 forming an exterior. Here, the heating unit 150a may be a part of the case 150 .

Meanwhile, referring to FIG. 4 , the external object 200 may be disposed on the heating unit 150a so as to be disposed above the coil 110 . The external object 200 is disposed above the coil 110 with the heating unit 150a as a boundary.

Hereinafter, the coil 110 , the magnetic field shielding sheet 120 , and the metal plate 130 will be described in detail.

First, the coil 110 is formed in the form of generating magnetic flux according to the flow of current. The coil 110 is made of a conductor through which a current can flow, and the type of conductor constituting the coil 110 is not limited. Meanwhile, the shape of the coil 110 is not limited to a specific shape. In an embodiment, the coil 110 is a self-bonding Litz wire and may have a diameter of 0.1 or more, 5 strands or more, and 5 turns or more.

The magnetic field formed by the coil 110 is formed in all directions around the coil 110 . That is, not only the external object 200 disposed above the coil 110, but also other components constituting the electric range are exposed to the magnetic field. To prevent this, a magnetic field shielding sheet 120 for shielding a magnetic field formed by the coil 110 is disposed below the coil 110 .

5 is a cross-sectional view of a magnetic field shielding sheet according to an embodiment of the present invention.

The magnetic field shielding sheet 120 plays the most important role in shielding the magnetic field formed below the coil 110 . Referring to FIG. 5 , the magnetic field shielding sheet 120 includes an adhesive layer 121 , a shielding layer 122 , and a protective layer 123 .

Referring to FIG. 5 , the adhesive layer 121 is disposed at the lowermost end of the magnetic field shielding sheet 120 . The shielding layer 122 is disposed on the adhesive layer 121 and overlaps at least a portion of the adhesive layer 121 . The protective layer 123 is disposed on the shielding layer 122 and overlaps at least a portion of the shielding layer 122 . Hereinafter, the components included in the magnetic field shielding sheet 120 will be described in more detail.

The adhesive layer 121 allows the magnetic field shielding sheet 120 and the metal plate 130 to be adhered (refer to FIG. 3 ), and the shielding layer 122 to be described later maintains a constant shape. The adhesive layer 121 may be formed of a resin deformable by heat or external force. Through this, the shape of the adhesive layer 121 may vary depending on the shape of the metal plate 130 or the shielding layer 122 , and a portion of the adhesive layer 121 may be filled in the gap formed in the shielding layer 122 . be able to This will be described later.

On the other hand, the thickness of the adhesive layer 121 is not limited, but must be made to a thickness sufficient to have an adhesive force capable of fixing the shielding layer 122 on the metal plate 130 .

Meanwhile, a shielding layer 122 may be disposed on the adhesive layer 121 . The shielding layer 122 performs a substantially shielding function in the magnetic field shielding sheet 120 , blocks a magnetic field from being formed on the lower side of the coil 110 , and allows the magnetic field to be concentrated on the upper side of the coil 110 .

In order to increase the output and efficiency of the electric range, the shielding ability of the shielding layer 122 should be high, and the loss in the shielding layer 122 should be small. In this specification, the shielding layer 122 will be described from the above two viewpoints.

First, the shielding ability of the shielding layer 122 will be described. In this specification, the shielding ability is defined as the intensity of the maximum external magnetic field at which the shielding layer 122 does not reach a saturation state. Meanwhile, separately from this, the expression shielding rate is used as a term expressing the degree to which the magnetic field strength is reduced by the shielding layer 122 . For example, if it is assumed that the magnetic field strength measured from one surface of the shielding layer 122 adjacent to the coil 110 is 100, and the magnetic field strength measured from one surface and the other surface of the shielding layer 122 is 10, the shielding rate is say 90%.

In order to improve the shielding ability of the shielding layer 122 , the shielding layer 122 should have a high saturation magnetic flux density. When the saturation magnetic flux density of the shielding layer 122 is low, since the shielding layer 122 is saturated even at a low magnetic field strength, the strength of the magnetic field formed by increasing the strength of the current flowing through the coil 110 is increased, Improving the output is limited. On the other hand, when the saturation magnetic flux density of the shielding layer 122 is high, the shielding layer 122 does not become saturated and the range of magnetic field strength that can perform the shielding function is expanded, so that it can flow in the coil 110 . the current strength increases. Accordingly, it is possible to improve the output of the electric range.

As described above, the shielding layer 122 should have a high saturation magnetic flux density. To this end, the shielding layer 122 may be manufactured from an amorphous ribbon. Here, the amorphous ribbon is an alloy sheet manufactured in the form of a plate by a melt spinning method, and the shielding layer 122 may be manufactured by heat-treating the amorphous ribbon.

More specifically, the shielding layer 122 is manufactured by amorphizing an alloy of a predetermined composition, manufacturing an amorphous ribbon having a high saturation magnetic flux density, and then performing heat treatment. The heat treatment of the amorphous ribbon will be described later.

In order to impart a high saturation magnetic flux density to the shielding layer 122, the alloy constituting the amorphous ribbon may include at least one of B, C, N, Si, P, Co, Cu, Zr, Nb, and Ta and Fe. there is.

Here, Fe is an element that is a main component of the metal alloy, and the content of Fe is 78 to 85 wt. It can be %. The content of Fe is 85wt. %, the saturation magnetic flux density is increased, but unreacted Fe increases, and the amorphous formation ability is deteriorated.

Here, Si and B contribute to thermal stabilization of the amorphous phase as an amorphous forming element (Glass Forming Element). In particular, B allows the Fe elements to maintain a constant interval, so that the alloy can be stably amorphized.

Here, C, P, and N form magnetic materials (Fe3C, Fe2P, and Fe4N) through reaction with Fe, thereby suppressing the coarsening of metal crystals due to the pinning effect.

Here, Co is an amorphous forming element and contributes to thermal stabilization of the amorphous phase, and serves to reduce magnetostriction of the shielding layer 122 .

Here, Cu forms a local cluster in the process of heat-treating the amorphous ribbon, so that the nucleation of Fe nanocrystals is made around the Cu cluster.

Here, Zr, Nb and Ta prevent the rapid growth of crystal grains during the heat treatment of the amorphous ribbon.

The amorphous ribbon having the above composition has a higher saturation magnetic density than a material (eg, Mn-Zn ferrite) used as a conventional shielding agent. Specifically, the amorphous ribbon made of the above composition has a saturation magnetic flux density of 1.2 Tesla or more. Thereafter, through the heat treatment process, the saturation magnetic flux density of the amorphous ribbon increases to 1.5 Tesla or more. That is, the shielding layer 122 of the present invention has a saturation magnetic density of 1.5 Tesla or more.

However, even if the saturation magnetic flux density of the shielding layer 122 is high, when the magnetic permeability of the shielding layer 122 is high, the magnetic induction change amount with respect to the external magnetic field change of the shielding layer 122 is large, so that the saturation state even in a low external magnetic field. to reach For this reason, in view of the shielding ability of the shielding layer 122 , the magnetic permeability of the shielding layer 122 should be low.

However, when the magnetic permeability of the shielding layer 122 is too low, the shielding rate of the shielding layer 122 is lowered and thus the shielding function cannot be performed. Specifically, the magnetic permeability of the shielding layer 122 may be 400 to 1200 based on 100 kHz. When the magnetic permeability of the shielding layer 122 is less than 400 based on 100 kHz, the shielding ratio of the shielding layer 122 is reduced to less than 90%, and when it exceeds 1200 based on 100 kHz, the external magnetic field of the shielding layer 122 Sensitivity is increased, so that, despite the high saturation magnetic flux density, the shielding layer 122 reaches saturation in an external magnetic field of low intensity. As described above, the shielding layer 122 should have an appropriate level of magnetic permeability.

Since the permeability of the ribbon in the amorphous state is higher than 1200 based on 100 kHz, it is necessary to lower the permeability of the amorphous ribbon through heat treatment. Specifically, the shielding layer 122 is manufactured by heat-treating the amorphous ribbon. When the amorphous ribbon is heat-treated, a portion of the amorphous ribbon is crystallized. As the alloy particles are crystallized, the magnetic permeability of the shielding layer 122 is lowered and the saturation magnetic flux density is increased. That is, the heat treatment process of the amorphous ribbon improves the shielding ability of the shielding layer 122 . However, the heat treatment process may lower the magnetic permeability of the shielding layer 122 below the reference level, and may increase loss in the shielding layer 122 to be described later, so it should be performed in a limited manner. This will be described later.

Summing up with respect to the shielding ability of the shielding layer 122, the shielding layer 122 is 78 to 85wt. % of Fe, it should be in a crystallized state at least a part, it should have a saturation magnetic flux density of 1.5 Tesla or more, and have a magnetic permeability of 400 to 1200 based on 100 kHz. Through this, it is possible to increase the output of the electric range and reduce the thickness of the electric range at the same time.

In the above, the shielding ability of the shielding layer 122 has been described. Loss occurs in the shielding layer 122 due to the magnetic field generated by the coil 110 . In order to maximize the efficiency of the electric range, the loss in the shielding layer 122 should be minimized. Hereinafter, a configuration for minimizing the loss of the shielding layer 122 will be described.

Loss that may be generated in the shielding layer 122 can be largely divided into two types. The first is hysteresis loss, and the second is eddy current loss.

First, the hysteresis loss is a loss that occurs when a ferromagnetic material is magnetized by alternating current, and the loss occurs even if the shielding layer 122 does not reach a saturation state. The hysteresis loss increases as the coercive force of the shielding layer 122 increases.

The coercive force of the shielding layer 122 may increase as the shielding layer 122 is heat treated. That is, as the shielding layer is heat-treated, the shielding ability of the shielding layer 122 increases, but the loss also increases. In order to maximize the shielding ability of the shielding layer 122 and to minimize loss, the crystal grain size and crystallized area of the alloy in a crystallized state constituting the shielding layer 122 should be limited.

Specifically, the crystal grain size of the crystallized metal constituting the shielding layer 122 should be 50 nm or less. When the grain size of the alloy exceeds 50 nm, the hysteresis loss increases, and the efficiency of the electric range is inevitably lowered.

On the other hand, it is most preferable that the entire amorphous ribbon constituting the shielding layer 122 is crystallized with a grain size of 50 nm or less, but since the grain size changes rapidly during the heat treatment of the amorphous ribbon, the grain size of all alloy crystals is reduced to 50 nm or less. It is actually difficult to make it form. Accordingly, it is preferable that 20% or more of the total area of the shielding layer 122 be crystallized with a grain size of 50 nm or less.

On the other hand, the grain size and crystallized area of the alloy are also related to the eddy current loss, which will be described later. Hereinafter, the eddy current loss of the shielding layer 122 will be described.

The eddy current loss is a loss generated by an eddy current generated in the shielding layer 122 by a magnetic field generated in the coil 110 . In order to minimize the eddy current loss, the shielding layer 122 may be formed of a plurality of metal pieces made of the alloy.

Specifically, in the manufacturing process of the shielding layer 122 , the heat-treated amorphous ribbon may be separated into a plurality of pieces, or cracks may be formed in at least a portion of the amorphous ribbon. Here, when the adhesive layer 121 is made of a resin deformable by heat or external force, the adhesive layer 121 may permeate between the metal pieces. Through this, the adhesive layer 121 may increase the bonding force between the metal pieces, allow the shielding layer 122 to have a certain shape, and prevent foreign materials from entering between the metal pieces.

When the shielding layer 122 is formed of one plate, eddy currents in the shielding layer 122 are formed over the entire plate. On the other hand, when the shielding layer 122 is made of a plurality of metal pieces, an eddy current is generated in each of the metal pieces. Compared to that generated in the entire plate, the loss due to the eddy current is reduced when the eddy current is generated in each of the metal pieces. That is, as the number of metal pieces forming the shielding layer 122 increases, the loss due to the eddy current decreases.

It is preferable that the particle size of each of the metal pieces be several μm or less. When the particle size of each of the metal pieces exceeds several μm, the number of metal pieces constituting the shielding layer 122 cannot be increased.

Here, the grain size of the alloy constituting the metal pieces should be formed to be less than 50nm. When the grain size of the alloy exceeds 50 nm, it is difficult to form the grain size of the metal pieces to a few μm or less.

On the other hand, when at least a portion of the amorphous ribbon is not crystallized, it becomes difficult to separate the amorphous ribbon into a plurality of pieces or to form cracks. For this reason, 20% or more of the total area of the shielding layer 122 should be crystallized.

Summarizing the loss in the shielding layer 122 , in order to minimize the loss in the shielding layer 122 , it is preferable that 20% or more of the total area of the shielding layer 122 be crystallized with a grain size of 50 nm or less. Do. In addition, by configuring the shielding layer 122 with a plurality of metal pieces, it is possible to minimize the eddy current loss in the shielding layer 122 .

In the above, configurations for maximizing the shielding ability of the shielding layer 122 and minimizing the loss have been described. The shielding layer 122 is protected by the protective layer 123 covering the shielding layer 122 . Hereinafter, the protective layer 123 included in the magnetic field shielding sheet 120 will be described.

The protective layer 123 physically and chemically protects the shielding layer 122 from external substances. Specifically, the protective layer 123 prevents a plurality of metal pieces constituting the shielding layer 122 from leaking to the outside, and prevents the alloys constituting the shielding layer 122 from being exposed to the outside and oxidized.

There is no limitation on the material constituting the protective layer 123 . In an embodiment, the protective layer 123 may be made of polyamide.

The magnetic field shielding sheet 120 including the above-described adhesive layer 121 , the shielding layer 122 , and the protective layer 123 may be formed to a thickness of 20 μm to 20 mm, but is not limited thereto, and the magnetic shielding sheet 120 . The thickness of may vary depending on the output of the electric range to be implemented.

On the other hand, compared with the conventional shielding agent (Mn-Zn ferrite), the shielding sheet according to the present invention has superior shielding ability and a lower loss rate than the conventional shielding agent, even though it is formed to a thickness of one-tenth. For this reason, it is possible to reduce the thickness and weight of the electric range by using the shielding sheet according to the present invention. Actual performance of the electric range using the shielding sheet according to the present invention will be described later.

In the above, the magnetic field shielding sheet 120 has been described. The electric range according to the present invention includes a metal plate 130 disposed below the magnetic field shielding sheet 120 . Hereinafter, the metal plate 130 will be described.

In the electric range according to the present invention, the metal plate 130 plays three main roles. First, the metal plate 130 serves to assist in shielding the magnetic field of the magnetic shielding sheet 120 . Second, the metal plate 130 serves to shield the electric field generated as current flows in the coil 110 . Third, the metal plate 130 functions to radiate heat generated from the magnetic field shielding sheet 120 and the coil 110 to the outside.

To this end, the metal plate 130 may be made of a material having high electrical conductivity and thermal conductivity. For example, the metal plate 130 may be made of aluminum, copper, an electro-galvanized steel plate, etc., but is not limited thereto.

In order to perform the function of the above-described metal plate 130, the metal plate 130 must have a thickness of 5 μm or more. However, when the output of the electric range is 1 kW or more, in order for the metal plate 130 to completely shield the electric field generated from the coil 110 , the thickness of the metal plate 130 should be formed to be 100 μm or more. On the other hand, when the thickness of the metal plate 130 is thick, since the weight of the electric range may be excessively increased, the thickness of the metal plate 130 is preferably formed to be 1 mm or less. However, the present invention is not limited thereto.

In the above, the electric range comprising the coil 110 , the magnetic field shielding sheet 120 , and the metal plate 130 has been described. Hereinafter, an embodiment (hereinafter, Embodiment 1) of the above-described electric range will be described. Meanwhile, in order to compare the performance of the electric range, an electric range using Mn-Zn ferrite as a shielding agent (hereinafter, Comparative Example 1) will be described together.

Each of Example 1 and Comparative Example 1 is capable of 1kW-class output and includes a self bonding wire coil having an outer diameter of 90mm and an aluminum metal plate 130 having a thickness of 2mm.

In the case of Example 1, the thickness of the magnetic field shielding sheet 120 was 0.5 mm, and the length and width were 92 mm, respectively. In Comparative Example 1, the thickness of the magnetic field shielding sheet 120 was 5 mm, and the length and width were 60 mm and 15 mm, respectively. The thickness of the magnetic field shielding sheet 120 provided in Example 1 was 1/10 of the thickness of Comparative Example 1.

For each of Example 1 and Comparative Example 1 having the above-described configurations, an output change according to the amount of current flowing through the coil 110 was measured. The measurement results are shown in FIG. 6 . As a result of the measurement, Example 1 and Comparative Example 1 reached 1kW output when the coil 110 current was 29A and 32A, respectively. On the other hand, when the coil 110 current flowing in each of Example 1 and Comparative Example 1 was 30A, the output was 1030W and 930W, respectively.

According to the measurement result, the electric range according to the present invention has an output value that can be reached with a certain amount of coil current is higher than that of the conventional electric range. Through this, it can be seen that the electric range according to the present invention can have a higher output than the conventional electric range.

On the other hand, for each of Example 1 and Comparative Example 1 having the above-described configurations, the coil current amount was fixed to 30A, and the coil temperature change according to the electric range driving time was measured. The measurement results are shown in FIG. 7 . As a result of the measurement, when each of Example 1 and Comparative Example 1 was driven for 10 minutes, the coil temperatures were 128°C and 162°C, respectively.

According to the measurement result, it can be confirmed that, in the electric range according to the present invention, unnecessary energy consumed by the coil 110 is smaller than that of the conventional electric range. Through this, it can be seen that the electric range according to the present invention has higher efficiency than the conventional electric range.

In addition, since the thickness of the shielding sheet of the electric range according to the present invention is only 1/10 compared with the shielding sheet of the conventional electric range, the electric range according to the present invention becomes thinner and lighter than the conventional electric range. there is.

In the above, the performance of the electric range according to the invention and the conventional electric range were compared. Hereinafter, a modified example capable of further improving the performance of the electric range according to the present invention will be described. As a specific modification, the magnetic field shielding sheet 120 according to the present invention may include a plurality of shielding layers.

The magnetic field shielding sheet 120 including a plurality of shielding layers may be formed in a form in which adhesive layers and shielding layers are alternately overlapped. Here, any one of the adhesive layers is disposed at the lowermost end of the magnetic field shielding sheet 120 . That is, the layer in contact with the metal plate 130 overlapping the bottom of the magnetic field shielding sheet 120 should be the adhesive layer 121 .

Meanwhile, the protective layer 123 should be disposed on the uppermost end of the magnetic field shielding sheet 120 . In addition, the protective layer 123 may be formed in plurality. In this case, the protective layer 123 may be disposed between any one of the shielding layers and the adhesive layer overlapped on the upper one of the protective layers. Specifically, when explaining the overlapping order of the magnetic field shielding sheet 120, the magnetic field shielding sheet 120 may be formed in an overlapping form in the order of the adhesive layer, the shielding layer, and the protective layer.

For example, referring to FIG. 8 , the magnetic field shielding sheet 120 includes the second adhesive layer 121b - the second shielding layer 122b - the second protective layer 123b - the first adhesive layer 121a - the first The first shielding layer 122a - the first protective layer 123a may be stacked in this order.

Here, since the adhesive layer and the protective layer are the same as the adhesive layer and the protective layer described in FIG. 2 , a detailed description thereof will be omitted.

On the other hand, when a plurality of shielding layers are configured, there are four major advantages.

First, the thermal conductivity of the magnetic field shielding sheet 120 may be improved. Specifically, the thermal conductivity and frequency characteristics of the magnetic field shielding sheet 120 may be improved by changing the composition of the alloy constituting the plurality of shielding layers.

In one embodiment, in order to increase the thermal conductivity of the magnetic field shielding sheet 120, the closer the distance to the coil 110, the closer the shielding layer is composed of a composition having a relatively high shielding ability, and As the distance increases, the shielding layer may be configured with a composition having a relatively high thermal conductivity. For example, the closer the distance to the coil 110 (toward the upper side of the magnetic field shielding sheet 120), the higher the Fe content of the shielding layer, and the greater the distance from the coil 110 (the magnetic field shielding) The Cu content of the shielding layer may be relatively increased (toward the lower side of the sheet 120 ).

Through this, the magnetic field shielding rate at a position adjacent to the coil 110 is increased, and the heat of the upper part of the magnetic field shielding sheet 120 that can generate a relatively large amount of heat is rapidly transferred to the lower side, thereby reducing the magnetic field shielding sheet 120 . It is possible to improve the heat dissipation performance.

Second, the frequency characteristic of the magnetic field shielding sheet 120 can be improved. Specifically, by varying the magnetic permeability of the plurality of shielding layers, the magnetic field shielding sheet 120 may have excellent shielding ability in a wider range of frequencies.

When shielding the high frequency magnetic field, it is advantageous that the magnetic permeability of the shielding layer is low, and on the contrary, when shielding the low frequency magnetic field, it is advantageous that the magnetic permeability of the shielding layer is high. Accordingly, by stacking the shielding layers in the order of high or low magnetic permeability, the magnetic field shielding sheet 120 can have high shielding ability in both high-frequency and low-frequency magnetic fields.

In this case, in the heat treatment process of the amorphous ribbon, by varying the heat treatment time for each shielding layer, the magnetic permeability of the shielding layer can be adjusted differently. For example, as the distance between the shielding layer and the coil 110 increases, the heat treatment time may be increased so that the shielding layer may have a low magnetic permeability.

Third, the manufacture of the magnetic field shielding sheet 120 is facilitated. Specifically, when the thickness of the shielding layer to be implemented is divided into a plurality of layers, manufacturing is facilitated. For example, when manufacturing a 500 ㎛ shielding layer, it is preferable to prepare 20 25 ㎛ shielding layers rather than manufacturing a shielding layer consisting of a single layer.

This is because the shielding layer is manufactured by a melt spinning method. Specifically, the shielding layer is manufactured by manufacturing the metal plate 130 in an amorphous state through melt spinning, and then performing heat treatment. When manufacturing the metal plate 130 through molten spinning, if the thickness of the metal plate 130 is too thick or too thin, it becomes difficult to uniformly form the thickness of the metal plate 130 . Therefore, the thickness of the metal plate 130 manufactured through melt spinning is preferably 15 to 30㎛. As described above, when manufacturing a shielding layer thicker than 30 μm, it is preferable to divide it into a plurality of layers.

Fourth, eddy current loss in the shielding layer can be reduced. Implementing the shielding layer of a certain thickness with a plurality of layers actually means implementing the shielding layer with a plurality of metal pieces. As the number of metal pieces constituting the shielding layer increases, eddy current loss may decrease.

In the above, the magnetic field shielding sheet 120 including a plurality of shielding layers has been described. Hereinafter, the heat treatment method of the shielding layer 122 according to the present invention will be described in detail.

The shielding layer 122 is manufactured by manufacturing an amorphous ribbon through melt spinning, and then performing heat treatment. The heat treatment process is performed to crystallize a portion of the amorphous ribbon.

Here, the heat treatment temperature and heat treatment time are important factors in controlling the crystallization rate and crystal size of the amorphous alloy. In particular, when the heat treatment temperature is too low, the amorphous alloy does not convert to a crystallized state, and when the heat treatment temperature is too high, it is difficult to control the grain size and crystallization rate because the entire amorphous metal is rapidly converted to a crystallized state.

The heat treatment temperature may be determined through differential scanning calorimetry (DSC) of the amorphous ribbon. Specifically, the DSC analysis is performed on the amorphous alloy to calculate the first and second crystallization temperatures, and then the heat treatment temperature is set between the first crystallization temperature and the second crystallization temperature.

For example, FIG. 9 shows the results of DSC analysis of an amorphous ribbon having an Fe content of 83.5 at%, B content of 8.0 at%, Si content of 4.0 at%, P content of 3.8 at%, and Cu content of 0.7 at%. It is a graph representing

Referring to FIG. 9 , peaks are observed at about 370° C. and 515° C., which correspond to the first and second crystallization temperatures of the amorphous ribbon. After the amorphous ribbon described in FIG. 9 was heat-treated at 475° C. for 30 minutes, X-ray diffraction was performed.

Referring to FIG. 10 , it can be confirmed that a portion of the heat-treated amorphous ribbon is crystallized through a pick that is not observed in the amorphous ribbon before the heat treatment. Meanwhile, the heat treatment time may vary depending on the grain size and crystallization ratio to be implemented.

Meanwhile, the results of analyzing the physical properties of the amorphous ribbon described in FIG. 10 are shown in Table 1 below.

Saturated magnetic flux density
(Tesla) coercive force
(A/m) Amorphous ribbon before heat treatment 1.53 92 Amorphous ribbon after heat treatment at 475℃ 1.68 114

Referring to Table 1, it can be seen that the saturation magnetic flux density increases when the amorphous ribbon is heat treated. Therefore, when the shielding layer 122 is manufactured by heat-treating the amorphous ribbon, the shielding ability of the shielding layer 122 may be improved.

However, when the amorphous ribbon is heat-treated, it can be seen that the coercive force increases. When the coercive force increases, the loss in the shielding layer 122 increases, which is a factor that reduces the efficiency of the electric range. Therefore, heat treatment for the amorphous ribbon should be limitedly performed.

In conclusion, it is preferable that the heat treatment of the amorphous ribbon be performed only until 20% or more of the total area of the amorphous ribbon is crystallized with a grain size of 50 nm or less.

As described above, since the magnetic field shielding sheet 120 according to the present invention has a higher saturation magnetic flux density than that of a conventional shielding agent, it is possible to increase the external magnetic field strength applied to the shielding sheet. Accordingly, it is possible to implement an electric range capable of outputting a higher output than the conventional electric range.

In addition, since the magnetic field shielding sheet 120 according to the present invention has less hysteresis loss and eddy current loss due to shielding than conventional shielding agents, when the magnetic field shielding sheet 120 is used, an electric range having higher efficiency than a conventional electric range can be implemented.

In addition, since the magnetic field shielding sheet 120 according to the present invention has excellent shielding performance even at a thinner thickness than the conventional shielding agent, when the magnetic field shielding sheet 120 is used, it is lighter than the conventional electric range and has a thinner thickness. can be implemented.

On the other hand, when the above-described magnetic field shielding sheet 120 and the ferrite sintered body are used together, the shielding performance of the electric range can be improved.

Specifically, referring to FIG. 11 , the ferrite sintered body has a low saturation magnetic flux density compared to the magnetic field shielding sheet (partial nanocrystal material) described above, and the magnetic flux density change rate according to the external magnetic field change (hereinafter, the magnetic flux density change rate) ) is low. Due to the low saturation magnetic flux density, the ferrite sintered body is difficult to be used as a shielding agent for an electric range. However, the low magnetic flux density change rate of the ferrite sintered body is a characteristic that can increase the efficiency of the electric range.

In the present invention, in order to utilize the low magnetic flux density change rate of the ferrite sintered body, the magnetic field shielding agent may have an appropriate level of saturation magnetic flux density and magnetic flux density change rate by using the ferrite sintered body and the above-described magnetic field shielding sheet together.

Hereinafter, the structure of the electric range for using the above-described magnetic field shielding sheet and the ferrite material together will be described.

12A to 12B are exploded views of an electric range according to the present invention.

The electric range according to the present invention is disposed under the coil 210 so as to overlap the coil 210, the magnetic field shielding sheet 220 having a metal alloy, and the magnetic field shielding sheet disposed under the coil 210 It includes a ferrite sintered body 260 and a metal plate 230 disposed below the ferrite sintered body 260 .

Here, the description of the coil 210 , the magnetic field shielding sheet 220 , and the metal plate 230 is replaced with the description of FIGS. 3 to 5 .

On the other hand, the ferrite sintered body 260 may be formed in a sheet form, or may be formed in a form suitable for manufacturing a circle, a rectangle, a hexagon, etc., and may have a form having a center hole according to a wiring structure.

For example, as shown in FIG. 12A , the ferrite sintered body 260 may be formed in a bar shape, and a plurality of ferrite sintered bodies 260 may be disposed between the magnetic field shielding sheet 220 and the metal plate 230 . Each of the plurality of ferrite sintered bodies is disposed to overlap the coil, and may be disposed at different positions depending on the structure and wiring structure of the electric range.

Meanwhile, as shown in FIG. 12A , the magnetic field shielding sheet may be formed in a rectangular sheet shape having a center hole structure 221 , but is not limited thereto, and the magnetic field shielding sheet may have various shapes such as a circle, a hexagon, and the like.

For another example, as shown in FIG. 12B , the ferrite sintered body 260 ′ may be formed of a circular sheet including a center hole structure 261 ′. In this case, the ferrite sintered body 260 may be formed to overlap the coil 210 . Meanwhile, as shown in FIG. 12B , the magnetic field shielding sheet 220 ′ may be formed of a circular sheet including a center hole structure 221 ′.

In the electric range having the above-described structure, the performance of the electric range may vary depending on the type of the ferrite sintered compact, the thickness of the ferrite sintered compact, and the weight ratio between the magnetic field shielding sheet and the ferrite sintered compact.

The ferrite sintered body may include at least one of Mn-Zn ferrite, Co-Zn ferrite, Ni-Zn ferrite, Ni-Zn-Cu ferrite, Mg-Ni-Zn-Cu ferrite, and Mg-Zn ferrite.

Meanwhile, based on the total mass of the magnetic field shielding sheet and the ferrite sintered body, the magnetic field shielding sheet may be composed of 11 to 50 wt%, and the ferrite sintered body may be composed of 50 to 89 wt%. When the weight ratio of the ferrite sintered body is low, the rate of change of magnetic flux density in the entire shielding area under the coil is excessively high. On the other hand, when the weight ratio of the ferrite sintered body is increased, the saturation magnetic flux density of the shielding region is excessively low. When the magnetic flux density change rate of the shielding area is too high or the saturation magnetic flux density is too low, the output of the electric range cannot be increased over a certain level, so that the weight ratio of the magnetic field shielding sheet and the ferrite sintered body is within the above-mentioned range desirable.

On the other hand, it is preferable that the thickness of the magnetic field shielding sheet is 100 μm to 500 μm, and the thickness of the ferrite sintered body is 900 μm to 4000 μm. When the thickness of the magnetic field shielding sheet is less than 100 μm, the saturation magnetic flux density is too low, and when it exceeds 500 μm, the weight of the electric range may be excessively increased. On the other hand, when the thickness of the ferrite sintered body is less than 900 μm, it is difficult to obtain an effect of reducing the magnetic flux density change rate due to the ferrite sintered body, and when it exceeds 4000 μm, the weight of the electric range may be excessively increased.

On the other hand, it is preferable that the saturation magnetic flux density of the magnetic field shielding sheet is 1.5 tesla or more, and the saturation magnetic flux density of the ferrite sintered body is 0.5 tesla or more. In addition, based on 100 kHz, the magnetic permeability of the magnetic shielding sheet is preferably 400 to 1200, and the magnetic permeability of the ferrite sintered body is 500 or more. It is preferable that the saturation magnetic flux density of the magnetic field shielding sheet is greater than that of the ferrite sintered body so that the shielding region has a saturation magnetic flux density of a certain level or more. Meanwhile, it is preferable that the magnetic permeability of the ferrite sintered body is greater than that of the magnetic field shielding sheet so that the shielding area has an appropriate level of change in magnetic flux density.

In the above, the electric range comprising the coil 210 , the magnetic field shielding sheet 220 , the ferrite sintered body 260 and the metal plate 230 has been described. Hereinafter, an embodiment (hereinafter, Embodiment 2) of the above-described electric range will be described. Meanwhile, in order to compare the performance of the electric range, an electric range using Mn-Zn ferrite as a shielding agent (the comparative example described above) will be described together.

Each of Example 2 and Comparative Example 2 is capable of 1kW-class output and includes a self bonding wire coil having an outer diameter of 90mm and an aluminum metal plate 230 having a thickness of 2mm.

In the case of Example 2, six ferrite sintered bodies of a rectangular parallelepiped (thickness: 1mm, length: 35mm, width: 15mm) were attached to a magnetic field shielding sheet having a thickness of 0.3 mm as shown in FIG. 12A in a radial form.

In the case of Comparative Example 2, six ferrite sintered bodies of a rectangular parallelepiped (thickness: 5mm, length: 35mm, width: 15mm) were attached to the mica plate in a radial form. The thickness of the shielding agent provided in Example 2 was about 1/4 of the thickness of Comparative Example 2.

For each of Example 2 and Comparative Example 2 having the above-described configurations, an output change according to the amount of current flowing through the coil 210 was measured. As a result of the measurement, Example 2 and Comparative Example 2 reached 1kW output when the coil 210 current was 28A and 32A, respectively.

According to the measurement result, the electric range according to the present invention has an output value that can be reached with a certain amount of coil current is higher than that of the conventional electric range. Through this, it can be seen that the electric range according to the present invention can have a higher output than the conventional electric range.

It is apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit and essential characteristics of the present invention.

In addition, the above detailed description should not be construed as restrictive in all respects but as exemplary. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the present invention are included in the scope of the present invention.

Claims (20)

In the electric range of the induction heating method,
coil;
a metal plate disposed under the coil to overlap the coil; and
and a magnetic field shielding sheet disposed between the coil and the metal plate and configured to shield at least a portion of a magnetic field formed in the coil,
The magnetic field shielding sheet,
adhesive layer;
a shielding layer laminated on the adhesive layer and made of an alloy; and
and a protective layer laminated on the shielding layer,
The shielding layer is made of a plurality of metal pieces made of the alloy,
The plurality of metal pieces includes an alloy composed of Fe and at least one of B, C, N, Si, P, Co, Cu, Zr, Nb and Ta,
At least a portion of the alloy is in a crystallized state,
The content of Fe in the alloy is 78 to 85 wt. %, characterized in that the electric range. delete delete delete delete delete According to claim 1,
At least a portion of the alloy is characterized in that the grain size (grain size) is 50 nm or less,
20% or more of the total area of the shielding layer is made of the alloy in a crystallized state, and the remainder is made of the alloy in an amorphous state. delete According to claim 1,
The magnetic field shielding sheet,
a plurality of adhesive layers;
a plurality of shielding layers made of the alloy; and
It includes a protective layer disposed on the top of the magnetic shielding sheet,
Any one of the adhesive layers is disposed at the bottom of the magnetic shielding sheet,
The adhesive layers and the shielding layers are arranged to alternately overlap each other in the order of the adhesive layer and the shielding layer,
The protective layer is a plurality,
The electric range, characterized in that the protective layer is disposed between any one of the shielding layers and the adhesive layer overlapped on the upper side of the one. delete 10. The method of claim 9,
The alloy constituting each of the shielding layers is made of Cu,
The Fe content of the alloy constituting each of the shielding layers increases toward the upper side of the magnetic shielding sheet,
The Cu content of the alloy constituting each of the shielding layers is an electric range, characterized in that it decreases toward the upper side of the magnetic shielding sheet. delete delete delete delete delete delete delete delete delete

Images