Magnetic heating structure and cooking utensil

Abstract

This invention provides a magnetic heating structure and a cooking appliance. The magnetic heating structure includes multiple material layers, and the thickness of each material layer satisfies the following formula: #imgabs0# where α is the equivalent heating coefficient of the magnetic heating structure, and δ1 to δ n The thickness of the first to nth layers of material in the magnetic heating structure from the outside to the inside, λ1 to λ n The thermal conductivity of the first to nth layers of the magnetic heating structure from the outside to the inside, ρ1 to ρ n The density of the first to nth layers of material in the magnetic heating structure from the outside to the inside, wherein c1 to c n Let h be the specific heat capacity of the first to nth layers of the magnetic heating structure from the outside to the inside, and let a, b, and c be constants. The technical solution of this invention solves the defect of low heating efficiency of the inner pot in existing rice cookers.

Description

Technical Field

[0001] The present invention relates to the technical field of cooking utensils, and in particular to a magnetic heating structure and a cooking utensil. Background Art

[0002] IH rice cookers are cooking appliances that heat food through the principle of electromagnetic induction. Energy efficiency is an important evaluation indicator of the basic performance of rice cookers, and low-energy-efficiency products will be gradually eliminated. Since the energy efficiency of IH rice cookers is generally higher than that of heating plate rice cookers, high-energy-efficiency products represented by IH technology have become the main trend of the development of the rice cooker industry.

[0003] The working principle of an IH rice cooker is roughly as follows: a high-frequency alternating current is input into the coil disk at the bottom of the pot body, and the current flows through the excitation coil to generate an alternating magnetic field. The alternating magnetic field acts on the inner pot with a magnetic conductive layer, and the magnetic lines of force generate induced eddy currents in the inner pot, generating eddy current heat to heat the pot and the food in the pot. The existing IH rice cooker inner pot is generally made of a composite of magnetic conductive stainless steel, aluminum alloy or copper and other materials. The magnetic conductive stainless steel serves as the eddy current heat generating layer, and its main function is to generate heat in the alternating magnetic field to provide heat for the inner pot. The aluminum alloy and copper materials serve as high thermal conductivity layers, and their thermal conductivity coefficients are high. The high thermal conductivity layer can quickly and evenly transfer the heat generated by the magnetic conductive stainless steel layer to all parts of the inner pot.

[0004] When designing the inner pot, if the high thermal conductivity layer of the inner pot is too thin, the heat transfer speed is slow, and problems such as local overheating and uneven heating will occur. If the high thermal conductivity layer of the inner pot is too thick, the inner pot body must be heated before heating the food. The inner pot itself will absorb a lot of heat, causing heat waste, slow heating speed, low heating efficiency, and material waste, increasing material costs. However, the prior art lacks a design method for high-efficiency inner pots, resulting in low heating efficiency in the inner pots of current rice cookers. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defect of low heating efficiency of the inner pot of the electric rice cooker in the prior art, thereby providing a magnetic heating structure and a cooking utensil.

[0006] In order to solve the above problems, the present invention provides a magnetic conductive heating structure, comprising multiple material layers, and the thickness of each material layer satisfies the following formula:

[0007] Wherein, α is the equivalent heating coefficient of the magnetic heating structure, δ1 to δ n is the thickness of the first layer of material to the nth layer of material from the outside to the inside of the magnetic heating structure, in mm, and the λ1 to the λ nis the thermal conductivity of the first layer of material to the nth layer of material from the outside to the inside of the magnetic heating structure, in units of W / (m·℃), and the values ​​of ρ1 to ρ n The density of the first layer of material to the nth layer of material from the outside to the inside of the magnetic heating structure is kg / m3. n is the specific heat capacity of the first layer of material to the nth layer of material from the outside to the inside of the magnetic heating structure, and the unit is kJ / (kg·℃); h is the height of the magnetic heating structure, and the unit is mm; a, b and c are all constants.

[0008] Optionally, the α and the heating efficiency of the magnetic heating structure are converted by the following relationship: η=0.8793α 3 -2.175α 2 +1.8032α+0.4305; wherein, η is the heating efficiency of the electrothermal heating structure, and α is in the range of 0.4 to 1.1.

[0009] Optionally, a is 0.1, b is 7, and c is 0.5.

[0010] Optionally, the thickness of the first layer of material from the outside to the inside of the magnetic conductive heating structure is obtained by the following formula: Wherein, δ1 is the thickness of the first layer of material from the outside to the inside of the magnetic heating structure, in mm, f is the excitation frequency of the coil, in Hz, and μ r is the relative magnetic permeability of the first layer material from the outside to the inside of the magnetic heating structure, μ0 is the vacuum magnetic permeability, and its value is 4π×107H / m, and σ is the electrical conductivity of the first layer material from the outside to the inside of the magnetic heating structure, and its unit is S / m.

[0011] Optionally, the magnetic heating structure is an inner pot of a cooking utensil.

[0012] Optionally, among the multiple material layers, the outermost material layer is made of stainless steel, and the remaining material layers are made of aluminum alloy or copper.

[0013] Optionally, among the multiple material layers, the thickness of the outermost material layer is in the range of 0.3 to 1.4 mm, and the total thickness of the remaining material layers is in the range of 0.6 to 2.7 mm.

[0014] Optionally, the material layer comprises a first material layer (10) and a second material layer (20) which are arranged in sequence from the outside to the inside, the thickness of the first material layer (10) is in the range of 0.3 to 1.4 mm, and the thickness of the second material layer (20) is in the range of 0.8 to 2 mm.

[0015] Optionally, the material layer further comprises a third material layer (30), wherein the third material layer (30) is located on the inner side of the second material layer (20), and the thickness of the third material layer (30) is in the range of 0.3 to 1 mm.

[0016] The present invention also provides a cooking utensil, comprising the above-mentioned magnetic conductive heating structure.

[0017] Optionally, the cooking utensil is an electric rice cooker or an electric pressure cooker, comprising a pot body and a pot cover arranged on the pot body, a coil disk being arranged at the bottom of the pot body, and the cooking utensil further comprising an inner pot (100), the inner pot (100) being placed in the pot body and located above the coil disk, the inner pot forming the magnetic conductive heating structure.

[0018] The present invention has the following advantages:

[0019] By utilizing the technical solution of the present invention, the material thickness, material properties and heating efficiency of different magnetic heating structures are recorded and experimented, and an equivalent heating efficiency model is established. When designing the magnetic heating structure, the heating efficiency and material properties of the target magnetic heating structure to be designed are substituted into the equivalent heating efficiency model, and the material thickness of the magnetic heating structure that meets the target heating efficiency can be designed, ensuring that the magnetic heating structure has a high heating efficiency. At the same time, the material thickness of the magnetic heating structure is designed by the equivalent heating efficiency model, which has the characteristics of fast design and high efficiency. Therefore, the technical solution of the present invention solves the defect of low heating efficiency of the inner pot of the electric rice cooker in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic structural diagram of the magnetic conductive heating structure of the present invention is shown;

[0022] Figure 2 Shows Figure 1 A magnified schematic diagram of the middle part; and

[0023] Figure 3 A schematic diagram of the thermal efficiency of different inner pots designed according to the method for designing the material thickness of the magnetic heating structure of the present invention is shown.

[0024] Description of reference numerals:

[0025] 10. first material layer; 20. second material layer; 30. third material layer; 100. inner pot. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] The method for designing the material thickness of the magnetic conductive heating structure of this embodiment includes:

[0031] Step S1: establishing an equivalent heating efficiency model through experiments according to the material thickness, material properties and heating efficiency of different magnetic heating structures;

[0032] Step S2: Substitute the heating efficiency of the target magnetic heating structure and the characteristics of the material of the target magnetic heating structure into the equivalent heating model to obtain the material thickness of the target magnetic heating structure.

[0033] By using the technical solution of this embodiment, the material thickness, material properties and heating efficiency of different magnetic heating structures are recorded and experimented, and an equivalent heating efficiency model is established. When designing the magnetic heating structure, the heating efficiency and material properties of the target magnetic heating structure to be designed are substituted into the equivalent heating model, and the material thickness of the magnetic heating structure that meets the target heating efficiency can be designed, ensuring that the magnetic heating structure has a high heating efficiency. At the same time, the material thickness of the magnetic heating structure is designed by the equivalent heating efficiency model, which has the characteristics of small design and high efficiency. Therefore, the technical solution of this embodiment solves the defect of low heating efficiency of the inner pot of the electric rice cooker in the prior art.

[0034] It should be noted that the material properties of the magnetic heating structure refer to the relative magnetic permeability, electrical conductivity, thermal conductivity, density, specific heat capacity, etc. of the magnetic heating structure. When the material of a certain layer of the magnetic heating structure is determined (for example, stainless steel, aluminum alloy, copper, etc.), the material can be determined. The material thickness, material properties and heating efficiency of different magnetic heating structures are tested, and the test data results are fitted with functions to obtain the equivalent heating efficiency model of the magnetic heating structure.

[0035] Those skilled in the art can understand that any structure that uses electromagnetic induction for heating can be used as a magnetic heating structure. For example, the magnetic heating structure can be an inner pot of an IH rice cooker or an electric pressure cooker, or a pot for an induction cooker, an electromagnetic hot pot, a heat-conducting component of an electromagnetic wall-mounted furnace, and a heat-conducting component of an electromagnetic heating mold, etc. For ease of explanation, the design method of this embodiment is described below using an inner pot. Of course, those skilled in the art can understand that the following design method can be fully applied to the various electromagnetic heating components exemplified above.

[0036] like Figure 1 and Figure 2 As shown in the figure, the inner pot 100 is generally composed of multiple layers of materials, mainly including an eddy current heat generating layer and a high thermal conductivity layer. In this embodiment, the inner pot 100 includes a first material layer 10, a second material layer 20 and a third material layer 30. Among them, the first material layer 10 is used as an induction eddy current heat generating layer, which is composed of magnetic materials such as magnetic conductive stainless steel, and generates heat through electromagnetic induction eddy currents to heat the inner pot 100 and the food in the inner pot 100 as a heating heat source. The second material layer 20 and the third material layer 30 are used as high thermal conductivity layers, mainly made of materials with good thermal conductivity such as aluminum alloy and copper.

[0037] In this embodiment, the first material layer 10 is generally composed of magnetic stainless steel material. A high-frequency alternating current is passed through the coil of the IH rice cooker to produce an alternating magnetic field in the space around the coil. The magnetic stainless steel layer generates induced eddy currents in the alternating magnetic field. The induced eddy currents generate heat, which serves as a heat source for the IH rice cooker to heat the inner pot 100 and the food in the inner pot 100. The second material layer 20 is a high thermal conductivity layer, which is composed of high thermal conductivity materials such as aluminum alloy and copper. It is used to conduct the heat generated by the heat generating layer to the entire inner pot 100, so that the inner pot body as a whole quickly heats up, increases the average temperature of the inner pot 100, enhances the heat exchange performance between the inner pot 100 and the food in the pot, and improves the heating efficiency. The third material layer 30 is a high thermal conductivity layer, which has the same function as the second material layer 20.

[0038] The 100% magnetic stainless steel layer in the inner pot of the IH rice cooker induces eddy currents to generate heat, which is then transferred to the entire inner pot body through the high thermal conductivity layer, causing the inner pot body to heat up quickly as a whole, increasing the average temperature of the inner pot body. The temperature difference between the inner pot body and the food in the pot increases, enhancing the heat exchange performance between the inner pot and the food in the pot, thereby improving the heating efficiency.

[0039] The speed of heat transfer in the inner pot mainly depends on the thermal conductivity and thickness of the inner pot material. The greater the thermal conductivity and thickness of the inner pot, the faster the heat conduction speed in the pot and the more uniform the temperature of the inner pot. The heating rate of the inner pot mainly depends on the specific heat capacity, density and thickness of the material. The smaller the specific heat capacity, density and thickness of the material, the faster the heating rate of the inner pot, the greater the temperature difference between the inner pot and the food in the pot, the faster the heat exchange speed and the higher the heating efficiency.

[0040] Therefore, the equivalent heating efficiency model is obtained through the following three theoretical formulas:

[0041] Thermal resistance of inner pot body:

[0042]

[0043] Calculation of heat diffusion in the pot:

[0044]

[0045] Lumped parameter method:

[0046]

[0047] The above three formulas are all conventional theoretical formulas. Those skilled in the art can understand their specific meanings and calculation methods, so they will not be described in detail.

[0048] Based on the lumped parameter method, through numerical simulation and experimental testing, the influence of material thermal resistance, heat capacity, and thermal diffusion on thermal efficiency was studied, and the functional relationship between the physical properties of the inner pot material, structural parameters, and equivalent heating efficiency was fitted. The inventor established a high-efficiency inner pot design calculation model, as follows:

[0049] The equivalent heating efficiency model includes:

[0050]

[0051] In the above formula, α is the equivalent heating rate of the magnetic heating structure, δ1 to δ n is the thickness of the first layer of material to the nth layer of material from the outside to the inside of the magnetic heating structure, λ1 to λ n is the thermal conductivity of the first layer of material to the nth layer of material from the outside to the inside of the magnetic heating structure, ρ1 to ρ n is the density of the first layer of material to the nth layer of material from the outside to the inside of the magnetic heating structure, c1 to c n is the specific heat capacity of the first layer of material to the nth layer of material from the outside to the inside of the magnetic heating structure, h is the height of the magnetic heating structure, and a, b and c are all constants.

[0052] Those skilled in the art can understand that when the material of a certain material layer of the inner pot 100 is determined, the thermal conductivity, density, and specific heat capacity of the material can all be determined. At the same time, the overall height of the inner pot 100 can be determined during design. Therefore, in the above-mentioned equivalent heating efficiency model, the variable is the thickness of each material layer. The equivalent heating rate that the inner pot 100 needs to achieve is brought into the above-mentioned equivalent heating efficiency model. As long as the thickness of each material layer of the designed inner pot 100 satisfies the above equation, the target equivalent heating efficiency can be met, ensuring that the designed inner pot has a higher efficiency.

[0053] Specifically, since the material layer in this embodiment includes a first material layer 10, a second material layer 20 and a third material layer 30, the above n can be 3. Those skilled in the art understand that when the number of material layers of the inner pot 100 is different, n can be a corresponding value.

[0054] The applicant obtained a large amount of data through simulation calculations, and then analyzed the relationship between the physical parameters, structural parameters and heating efficiency of the inner pot material based on the simulation data, and fitted the function of the inner pot material density, specific heat capacity, thermal conductivity, thickness, and inner pot height and equivalent heating efficiency, and then verified it through the national standard rice cooker energy efficiency test experiment. The larger the equivalent heating coefficient, the higher the heating efficiency of the inner pot, that is, the higher the thermal efficiency of the IH rice cooker. According to the applicant's experimental data, α (equivalent heating coefficient) and the heating efficiency of the magnetic heating structure are not linearly related. And α (equivalent heating coefficient) and the heating efficiency of the magnetic heating structure are converted through the following relationship:

[0055] η=0.8793α 3 -2.175α 2 +1.8032α+0.4305;

[0056] Wherein, η is the heating efficiency of the electrothermal heating structure, and preferably, α is in the range of 0.4 to 1.1. Specifically, when η is greater than 86%, the inner pot has the characteristics of high efficiency, and the corresponding α is 0.4. And when α is greater than 1.1, the value of η is greater than 1, which obviously does not conform to the design rule. Therefore, the final value of α is 0.4 to 1.1.

[0057] Specifically, the target heating efficiency η is substituted into the above formula, and then the equation group is solved to obtain the specific value of α, and then α is substituted into the above equivalent heating efficiency model, and the thickness of each material layer is designed.

[0058] In order to facilitate the selection of values, the applicant lists several commonly used corresponding relationships between heating efficiency and equivalent heating coefficient:

[0059] Equivalent heating efficiency α 0.4 0.557 0.585 0.652 0.694 0.869 Actual heating efficiency η 86％ 91.4％ 91.5％ 92.5％ 92.9％ 93.2％

[0060] Specifically, the heating efficiency of a high-efficiency inner pot is usually above 86%, so the equivalent heating efficiency corresponds to 0.4. Of course, when the target heating efficiency of the inner pot is designed to be other values, the target heating efficiency is substituted into the above formula to solve the equation group on the right side of the equation.

[0061] Furthermore, for the high-efficiency inner pot, when the target heating efficiency is greater than or equal to 86%, the corresponding equivalent heating efficiency is greater than or equal to 0.4.

[0062] Preferably, the above parameters a, b and c are specifically: a is 0.1, b is 7, and c is 0.5. Of course, those skilled in the art can adjust the values ​​of the above three parameters according to the fitting results of experimental data.

[0063] Furthermore, in order to generate induced eddy current heat and provide a heating source for the IH rice cooker, the outermost layer of the inner pot must be a magnetic stainless steel material, that is, the first material layer 10 is a magnetic stainless steel material, and the thickness of the magnetic stainless steel material is δ1. According to the skin effect in the electromagnetic heating process, the thickness δ1 of the magnetic stainless steel material should not be less than its skin depth δ0, so the thickness of the first layer of material 10 from the outside to the inside of the magnetic heating structure is obtained by the following formula:

[0064]

[0065] Among them, δ1 is the thickness of the first layer of material from the outside to the inside of the magnetic heating structure, f is the excitation frequency of the coil, μ r is the relative magnetic permeability of the first layer material from the outside to the inside of the magnetic heating structure, μ0 is the vacuum magnetic permeability, and σ is the electrical conductivity of the first layer material from the outside to the inside of the magnetic heating structure.

[0066] Combination Figure 2 It can be seen that the first layer of material from the outside to the inside is the first material layer 10 of the inner pot 100 .

[0067] The above formula is a conventional theoretical skin depth calculation formula. After δ1 is calculated using the above formula, it is substituted into the equivalent heating efficiency model, and then the thickness of other material layers is adjusted, and the value on the right side of the equal sign of the equivalent heating efficiency model is made greater than or equal to the target equivalent heating coefficient on the left side, so that the designed inner pot 100 has the characteristics of high efficiency.

[0068] like Figure 1 and Figure 2 As shown, this embodiment also provides a magnetic heating structure, which includes multiple material layers, and the thickness of each material layer is obtained by the above-mentioned design method. In the above-mentioned multiple material layers, the outermost material layer is made of stainless steel, and the remaining material layers are made of aluminum alloy or copper.

[0069] Preferably, the applicant designs the inner pot 100 according to the above-mentioned equivalent heating efficiency model, with a design target heating efficiency of 86%, a corresponding equivalent heating coefficient α of 0.4, and a design formula of:

[0070]

[0071] Here, n is 2 or 3.

[0072] And the thickness of the outermost material satisfies:

[0073]

[0074] Wherein, δ0 is the skin depth of magnetic stainless steel material.

[0075] The thickness of each layer of the inner pot in this embodiment is designed as follows: the thickness of the outermost magnetic conductive layer is in the range of 0.3 to 1.4 mm. When the thickness of the magnetic conductive layer is less than 0.3 mm, the thickness of the magnetic conductive layer is less than the skin depth, and the magnetic induction effect decreases. When the thickness of the magnetic conductive layer is greater than 1.4 mm, the thickness of the inner pot will be too thick, the overall weight will be too large, and it will not help to improve the heating efficiency. The overall thickness of the high thermal conductivity layer composed of the remaining material layers inside the magnetic conductive layer is in the range of 0.6 to 2.7 mm to ensure that the inner pot has a reasonable thickness.

[0076] For the inner pot, two-layer and three-layer structures are common. When the inner pot is a three-layer structure, the thickness of the other two layers of material layers except the magnetic conductive layer ranges from 0.8 to 2 mm and from 0.3 to 1 mm respectively. Of course, the inner pot can also be designed as a four-layer, five-layer or more-layer structure, as long as the total thickness of the other material layers except the magnetic conductive layer is within the range of 0.6 to 2.7 mm.

[0077] According to the above design formula and design rules, the applicant designed five sets of inner pots 100, and the data thereof are respectively:

[0078] 1. The material layer includes a first material layer 10 and a second material layer 20 which are sequentially arranged from the outside to the inside. The first material layer 10 is made of stainless steel, and the second material layer 20 is made of aluminum alloy. The thickness of the first material layer 10 is in the range of 0.7 to 1.6 mm, and the thickness of the second material layer 20 is in the range of 1.6 to 2.3 mm.

[0079] 2. The material layer includes a first material layer 10, a second material layer 20 and a third material layer 30 which are sequentially arranged from the outside to the inside, the first material layer 10 is made of stainless steel, the second material layer 20 is made of aluminum alloy, and the third material layer 30 is made of copper, wherein the thickness of the first material layer 10 is in the range of 0.3 to 1.4 mm, the thickness of the second material layer 20 is in the range of 0.8 to 2 mm, and the thickness of the third material layer 30 is in the range of 0.3 to 1 mm;

[0080] 3. The material layer includes a first material layer 10 and a second material layer 20 which are sequentially arranged from the outside to the inside, the first material layer 10 is made of stainless steel, and the second material layer 20 is made of aluminum alloy, wherein the thickness of the first material layer 10 is in the range of 0.3 to 1 mm, and the thickness of the second material layer 20 is in the range of 1 to 2.7 mm;

[0081] 4. The material layer includes a first material layer 10 and a second material layer 20 arranged in sequence from the outside to the inside, the first material layer 10 is made of stainless steel, and the second material layer 20 is made of aluminum alloy, wherein the thickness of the first material layer 10 is in the range of 0.7 to 1.3 mm, and the thickness of the second material layer 20 is in the range of 0.7 to 1.3 mm;

[0082] 5. The material layer includes a first material layer 10 and a second material layer 20 which are arranged in sequence from the outside to the inside. The first material layer 10 is made of stainless steel, and the second material layer 20 is made of aluminum alloy. The thickness of the first material layer 10 is in the range of 0.3 to 0.9 mm, and the thickness of the second material layer 20 is in the range of 1.1 to 1.7 mm.

[0083] After optimizing the data of the above five groups of inner pots, the inner pot data finally tested are: a two-layer pot with 1mm stainless steel and 2mm aluminum alloy, a three-layer pot with 0.6mm stainless steel and 1.9mm aluminum alloy and 0.5mm copper, a two-layer pot with 0.6mm stainless steel and 2.4mm aluminum alloy, a two-layer pot with 1mm stainless steel and 1mm aluminum alloy, and a two-layer pot with 0.6mm stainless steel and 1.4mm aluminum alloy.

[0084] The final test results are as follows Figure 3 As shown, the thermal efficiency of the five groups of inner pots is 86% higher than the design target, indicating that the five groups of inner pots have the characteristics of high efficiency.

[0085] Preferably, the magnetic heating structure is a cooker.

[0086] This embodiment also provides a cooking utensil, including the above-mentioned magnetic conductive heating structure. The cooking utensil is an electric rice cooker or an electric pressure cooker, the cooking utensil includes a pot body and a pot cover arranged on the pot body, a coil disk is arranged at the bottom of the pot body, and the cooking utensil also includes an inner pot 100, the inner pot 100 is placed in the pot body and above the coil disk, and the inner pot forms a magnetic conductive heating structure.

[0087] Of course, the cooking utensil may also be other cooking utensil that utilizes electromagnetic induction for heating.

[0088] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A magnetic heating structure, characterized in that: It includes multiple material layers, and the thickness of each material layer satisfies the following formula: Wherein, α is the equivalent heating coefficient of the magnetic heating structure, δ1 to δ n is the thickness of the first layer of material to the nth layer of material from the outside to the inside of the magnetic heating structure, in mm, and the λ1 to the λ n is the thermal conductivity of the first layer of material to the nth layer of material from the outside to the inside of the magnetic heating structure, in units of W / (m·℃), and the values ​​of ρ1 to ρ n The density of the first layer of material to the nth layer of material from the outside to the inside of the magnetic heating structure is kg / m3. n is the specific heat capacity of the first layer of material to the nth layer of material from the outside to the inside of the magnetic heating structure, and the unit is kJ / (kg·℃); h is the height of the magnetic heating structure, and the unit is mm; a, b and c are all constants.

2. The magnetic conductive heating structure according to claim 1, characterized in that: The α and the heating efficiency of the magnetic heating structure are converted by the following relationship: η=0.8793α 3 -2.175a 2 +1.8032a+0.4305; Wherein, η is the heating efficiency of the magnetic heating structure, and α is in the range of 0.4 to 1.

1.

3. The magnetic conductive heating structure according to claim 1, characterized in that: The a is 0.1, the b is 7, and the c is 0.

5.

4. The magnetic conductive heating structure according to claim 1, characterized in that: The thickness of the first layer of material from the outside to the inside of the magnetic conductive heating structure is obtained by the following formula: Wherein, δ1 is the thickness of the first layer of material from the outside to the inside of the magnetic heating structure, in mm, f is the excitation frequency of the coil, in Hz, and μ r is the relative magnetic permeability of the first layer material from the outside to the inside of the magnetic heating structure, μ0 is the vacuum magnetic permeability, and its value is 4π×107H / m, and σ is the electrical conductivity of the first layer material from the outside to the inside of the magnetic heating structure, and its unit is S / m.

5. The magnetic conductive heating structure according to claim 1, characterized in that: The magnetic conductive heating structure is an inner pot of a cooking utensil.

6. The magnetic conductive heating structure according to claim 1, characterized in that: Among the multiple material layers, the outermost material layer is made of stainless steel, and the remaining material layers are made of aluminum alloy or copper.

7. The magnetic conductive heating structure according to any one of claims 1 to 6, characterized in that: Among the multiple material layers, the thickness of the outermost material layer is in the range of 0.3 to 1.4 mm, and the total thickness of the remaining material layers is in the range of 0.6 to 2.7 mm.

8. The magnetic conductive heating structure according to claim 7, characterized in that: The material layers include a first material layer (10) and a second material layer (20) which are arranged in sequence from the outside to the inside, the thickness of the first material layer (10) is in the range of 0.3 to 1.4 mm, and the thickness of the second material layer (20) is in the range of 0.8 to 2 mm.

9. The magnetic conductive heating structure according to claim 8, characterized in that: The material layer further comprises a third material layer (30), wherein the third material layer (30) is located on the inner side of the second material layer (20), and the thickness of the third material layer (30) is in the range of 0.3 to 1 mm.

10. A cooking utensil, characterized in that: It comprises the magnetic heating structure as described in any one of claims 1 to 9.

11. The cooking device according to claim 10, characterized in that: The cooking utensil is an electric rice cooker or an electric pressure cooker, comprising a pot body and a pot cover arranged on the pot body, a coil disk being arranged at the bottom of the pot body, and an inner pot (100) being placed in the pot body and above the coil disk, the inner pot forming the magnetic conductive heating structure.

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