Induction heating coils and induction cookers

Abstract

To provide an induction heating coil that improves heating efficiency. [Solution] The induction heating coil comprises a conductor portion and a magnetic member. The conductor portion has an inner circumferential conductor portion, an outer circumferential conductor portion, and an intermediate conductor portion disposed between the inner circumferential conductor portion and the outer circumferential conductor portion. Each conductor of the inner circumferential conductor portion has a radial width Wi and an axial height Ti, each conductor of the outer circumferential conductor portion has a radial width Wo and an axial height To, and each conductor of the intermediate conductor portion has a radial width Wm and an axial height Tm. The conductor portion and the magnetic member satisfy the following conditions: Dci ≤ Dmi and Wi, where Dci is the radial distance from the central axis to the innermost circumferential surface of the inner circumferential conductor portion, Dco is the radial distance from the central axis to the outermost circumferential surface of the outer circumferential conductor portion, Dmi is the radial distance from the central axis to the inner diameter side end of the magnetic member, and Dmo is the radial distance from the central axis to the outer diameter side end of the magnetic member.

Description

Technical Field

[0001] The present disclosure relates to an induction heating coil and an induction heating cooker.

Background Art

[0002] An induction heating coil used in a conventional induction heating cooker is known, which arranges a magnetic member downward and efficiently induces magnetic flux in the object to be heated.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since the magnetic flux flowing through the magnetic member concentrates at the ends, the magnetic flux easily intersects with the conductor of the coil near the ends of the magnetic member, and eddy currents are likely to occur in the conductor. This eddy current causes a problem of reducing the heating efficiency of the induction heating coil.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to provide an induction heating coil that improves heating efficiency.

Means for Solving the Problems

[0006] The induction heating coil according to this disclosure includes a conductor part composed of a conductor wound around a central axis, and a magnetic member arranged along the radial direction of the conductor part, the magnetic member having an inner diameter side end portion which is an end face on the inner diameter side and an outer diameter side end portion which is an end face on the outer diameter side. The conductor part has an inner circumference conductor part arranged on the inner circumference side including the innermost circumference surface, an outer circumference conductor part arranged on the outer circumference side including the outermost circumference surface, and an intermediate conductor part arranged between the inner circumference conductor part and the outer circumference conductor part. Each conductor of the inner circumference conductor part has a radial width Wi and an axial height Ti, each conductor of the outer circumference conductor part has a radial width Wo and an axial height To, and each conductor of the intermediate conductor part has a radial width Wm and an axial height Tm. When the radial distances from the central axis to the innermost circumference surface of the inner circumference conductor part, the outermost circumference surface of the outer circumference conductor part, the inner diameter side end portion of the magnetic member, and the outer diameter side end portion of the magnetic member are Dci, Dco, Dmi, and Dmo respectively, at least one of Dci ≤ Dmi and Wi < Ti, and Dco ≥ Dmo and Wo < To is satisfied.

Effect of the Invention

[0007] According to this disclosure, the heating efficiency can be improved.

Brief Description of the Drawings

[0008] [Figure 1] It is an exploded perspective view showing an example of the induction heating coil according to Embodiment 1. [Figure 2] It is an exploded perspective view showing the appearance of an example of the induction heating cooker according to Embodiment 5. [Figure 3] It is a cross-sectional view of the induction heating coil according to Embodiment 1. [Figure 4] It is a cross-sectional view of each conductor per conductor part according to each embodiment. [Figure 5] It is a diagram schematically showing the flow of magnetic flux in the cross-section of the induction heating coil according to Embodiment 1. [Figure 6] It is a cross-sectional view of each conductor per inner circumference conductor part of the conductor part according to each embodiment. [Figure 7]It is a cross-sectional view of a conductor of the outer conductor part per one in the conductor part according to each embodiment. [Figure 8] It is a cross-sectional view of an induction heating coil according to Modification 1. [Figure 9] It is a cross-sectional view of an induction heating coil according to Modification 2. [Figure 10] It is a cross-sectional view of an induction heating coil according to Embodiment 2. [Figure 11] In the induction heating coil according to Embodiment 2, it is a cross-sectional view of an induction heating coil that satisfies only Xm < Xi. [Figure 12] In the induction heating coil according to Embodiment 2, it is a cross-sectional view of an induction heating coil that satisfies only Xm < Xo. [Figure 13] It is a diagram schematically showing the flow of magnetic flux in the cross section of the induction heating coil according to Embodiment 2. [Figure 14] It is a cross-sectional view of an induction heating coil according to Embodiment 3. [Figure 15] In the induction heating coil according to Embodiment 3, it is a cross-sectional view of an induction heating coil that satisfies only Wm > Wi. [Figure 16] In the induction heating coil according to Embodiment 3, it is a cross-sectional view of an induction heating coil that satisfies only Wm > Wo. [Figure 17] It is a diagram schematically showing the flow of magnetic flux in the cross section of the induction heating coil according to Embodiment 3. [Figure 18] It is a cross-sectional view of an induction heating coil according to Embodiment 4. [Figure 19] It is a perspective view showing a configuration example of a conductor part of the induction heating coil according to Embodiment 4. [Figure 20] It is a diagram schematically showing the flow of magnetic flux in the cross section of the induction heating coil according to Embodiment 4. [Figure 21] It is a cross-sectional view of an induction heating cooker according to Embodiment 5. [Figure 22] In the induction heating cooker according to Embodiment 5, it is a cross-sectional view of an induction heating cooker that satisfies only Gm = Gi. [Figure 23]In the induction heating cooker according to Embodiment 5, it is a cross-sectional view of an induction heating cooker that only satisfies Gm = Go.

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the induction heating coil and the induction heating cooker of the present disclosure will be described with reference to the drawings. In each figure, those denoted by the same reference numerals are the same or corresponding ones, which is common throughout the entire specification. Also, the forms of the components shown throughout the specification are merely examples and are not limited to these descriptions. Further, the drawings used in the following description may have a different relationship in the size of each component from the actual one. Furthermore, in each figure, for the sake of convenience of explanation, three coordinate axes of the X-axis, Y-axis, and Z-axis are shown to define the direction, but the arrangement of each component is not limited by the coordinate axes shown in the figure.

[0010] Embodiment 1. <Configuration of Induction Heating Coil 100> The configuration of the induction heating coil 100 according to Embodiment 1 will be described. FIG. 1 is an exploded perspective view showing an example of the induction heating coil 100 according to Embodiment 1. FIG. 2 is an exploded perspective view showing an example of the appearance of the induction heating cooker 200. FIG. 2 shows a state in which the top plate 9 is removed from the induction heating cooker 200 to make it easier to see the inside of the induction heating cooker 200. The induction heating coil 100 of Embodiment 1 is provided, for example, in the induction heating cooker 200 shown in FIG. 2. The induction heating coil 100 is applied to an induction heating cooker 200 that heats the object to be heated 6 placed on the top plate 9 shown in FIG. 2. The object to be heated 6 is, for example, a cooking utensil such as a metal pot. The configuration of the induction heating cooker 200 shown in FIG. 2 will be described in Embodiment 5.

[0011] The induction heating coil 100 comprises a conductor portion 1, a magnetic shielding ring 2, a magnetic member 3, and a coil base 4. The conductor portion 1 is made of a single conductor and is formed in a spiral shape. The direction of the Z-axis arrow, which is above the induction heating coil 100, is the surface facing the object to be heated 6 in the induction heating cooker 200 shown in Figure 2. The direction of the Z-axis arrow, which is below the induction heating coil 100, is the surface on which the magnetic member 3 is arranged. The conductor portion 1 is housed in a conductor housing groove 4a formed on the surface of the coil base 4. The back surface of the coil base 4 has a magnetic member housing groove (not shown), where the magnetic member 3 is housed. A magnetic shielding ring 2 is provided along the outer circumference of the coil base 4. For convenience of explanation, Figure 1 shows the conductor portion 1, the magnetic shielding ring 2, and the magnetic member 3 disassembled from the coil base 4.

[0012] The conductor portion 1 is composed of a metal conductor such as copper or aluminum. An insulating coating may or may not be formed on the surface of the conductor portion 1. If an insulating coating is formed, the insulating properties of the conductor portion 1 are improved, and its durability against external vibrations and shocks can be improved. If an insulating coating is not formed, the conductor cross-sectional area of ​​the conductor portion 1 can be increased, and the Joule loss generated in the conductor can be reduced by reducing electrical resistance.

[0013] Figure 3 is a cross-sectional view of the induction heating coil 100 according to Embodiment 1. Figure 3 schematically shows a cross-section of the induction heating coil 100 in Figure 1, cut along the XZ plane. The central axis CL of the winding of the conductor portion 1 is shown by a dashed line, and only the right-hand portion is represented.

[0014] As shown in Figure 3, the conductor portion 1 is composed of a conductor wound around a central axis CL. When the axial distance between the conductor portion 1 and the object to be heated 6 is small, the magnetic flux generated from the conductor portion 1 can be efficiently guided to the object to be heated 6, so it is desirable that the conductor portion 1 and the object to be heated 6 be close together. For this reason, it is desirable that the conductor portion 1 be wound in a spiral shape around the central axis CL. The surface of the conductor portion 1 faces the object to be heated 6 in the axial direction. The conductor portion 1 is configured to be wound so that, when viewed radially from the central axis CL of the winding, a predetermined distance is maintained between adjacent conductors.

[0015] Terminals (not shown) are attached to both ends of the conductor section 1. Lead wires (not shown) are connected to the terminals at both ends of the conductor section 1, and are electrically connected to the inverter board 7 provided on the induction heating cooker 200 shown in Figure 2. As a result, the high-frequency alternating current (hereinafter: high-frequency current) generated by the inverter board 7 is supplied to the conductor section 1 via the lead wires. In other words, the conductor section 1 functions as an electrical circuit through which current flows.

[0016] The conductor section 1 generates a high-frequency magnetic flux when a high-frequency current is passed through it from the inverter board 7. The generated magnetic flux links with the bottom surface of the object to be heated 6, which is placed directly above the induction heating coil 100. As a result, eddy currents are generated at the bottom surface of the object to be heated 6, and Joule heat is generated by the eddy currents and the resistance component of the object to be heated 6, heating the bottom of the object to be heated 6.

[0017] The magnetic shielding ring 2 is formed in an annular shape from, for example, an aluminum conductor and is provided on the coil base 4 so as to surround the outer circumference of the conductor portion 1. The magnetic shielding ring 2 is provided to reduce the leakage magnetic flux emitted to the outside of the housing 8 of the induction heating cooker 200 shown in Figure 2. Specifically, when the magnetic flux generated by the conductor portion 1 links with the magnetic shielding ring 2, eddy currents are generated in the magnetic shielding ring 2 in a direction that cancels out the linked magnetic flux. These eddy currents reduce the leakage magnetic flux to the outside of the housing 8.

[0018] The magnetic shielding ring 2 is formed in a ring shape by electrically connecting both ends of an aluminum conductor, for example, by crimping. Figure 1 shows an example where the magnetic shielding ring 2 is wound only once, but it may also be wound two or more times to short-circuit both ends. By winding it two or more times, the effect of reducing leakage magnetic flux to the outside of the housing 8 can be enhanced.

[0019] The magnetic member 3 is a magnetic material installed on the side of the conductor 1 opposite to the heating side, i.e., below the conductor 1. The magnetic member 3 increases the amount of magnetic flux generated around the conductor 1, and increases the magnetic flux flowing to the object to be heated 6. As shown in Figure 1, below the coil base 4, multiple magnetic members 3 are arranged radially from the center of the central axis CL, from the inner circumference to the outer circumference of the conductor 1. Figure 1 shows the case where there are 8 magnetic members 3, but the number of magnetic members 3 is not limited to 8.

[0020] The magnetic member 3 is rod-shaped and arranged along the radial direction of the conductor portion 1. The magnetic member 3 is positioned so that the longitudinal direction of the rod is parallel to the radial direction of the conductor portion 1, and has an inner diameter end 3a, which is the end face on the inner diameter side, and an outer diameter end 3b, which is the end face on the outer diameter side. The magnetic member 3 is made of a magnetic material such as ferrite.

[0021] The shape of the magnetic member 3 is not limited to the rod shape shown in Figure 1. For example, it may be an L-shape in which at least one end in the longitudinal direction rises perpendicularly toward the bottom surface of the object to be heated 6, or a U-shape in which both ends in the longitudinal direction rise perpendicularly toward the bottom surface of the object to be heated 6. In these configurations, the axial distance between the magnetic member 3 and the object to be heated 6 becomes shorter, making it easier for magnetic flux to flow from the magnetic member 3 to the object to be heated 6, thereby improving the heating efficiency of the object to be heated 6.

[0022] The coil base 4 is an insulating member that holds the conductor portion 1, the magnetic shielding ring 2, and the magnetic member 3. The coil base 4 is made of a non-magnetic material, such as resin. A magnetic member housing portion (not shown) for housing the magnetic member 3 is provided on the back surface of the coil base 4. The magnetic member 3 may be fixed to the magnetic member housing portion with, for example, an adhesive. The magnetic shielding ring 2 is provided on the outer circumference of the coil base 4 so as to surround the conductor portion 1.

[0023] The surface of the coil base 4 has a concave conductor housing groove 4a. The conductor housing groove 4a is formed to conform to the shape of the conductor portion 1, and the conductor portion 1 is housed within it. The conductor housing groove 4a has side walls 4b between radially adjacent conductor housing grooves 4a. In the conductor portion 1, radially adjacent conductors are kept at a predetermined distance from each other by the side walls 4b of the coil base 4. Therefore, insulation between radially adjacent conductors is ensured even without providing an insulating coating or the like on the conductor portion 1. With this configuration, for example, if the conductor portion 1 is deformed by an external impact, radially adjacent conductors may come into contact and short-circuit, preventing thermal damage to the conductor portion 1 due to overheating caused by the conduction of current between conductors.

[0024] Furthermore, by ensuring sufficient distance between adjacent conductors in the radial direction, the proximity effect, which increases the Joule loss of the conductor section 1, can be suppressed. The proximity effect is a phenomenon in which, when a high-frequency current flows through a conductor, high-frequency magnetic flux links with adjacent conductors in the radial direction, generating an induced electromotive force inside the conductor and causing a bias in the current distribution inside the conductor. As the distance between adjacent conductors increases, the effect of the proximity effect decreases.

[0025] Another method to suppress the proximity effect is to use Litz wire, which is constructed by bundling multiple coils, as the conductor section 1. However, since Litz wire consists of multiple coils with insulating coatings on the conductors, the cross-sectional area occupied by the insulating coating is large, and the cross-sectional area of ​​the conductor portion is small, resulting in high electrical resistance and high Joule loss in the coil. Therefore, with the configuration of the conductor section 1 according to Embodiment 1, the distance between adjacent conductors in the radial direction is secured to suppress the proximity effect, while increasing the conductor cross-sectional area. As a result, the electrical resistance of the conductor section 1 is reduced, and the Joule loss generated in the conductor section 1 is reduced. This improves the heating efficiency of the induction heating coil 100.

[0026] Furthermore, the coil base 4 may have a configuration in which the bottom surface of the recess in the conductor housing groove 4a is not partially provided. That is, a part of the bottom surface of the coil base 4 may be provided as a through-hole. With this configuration, by supplying cooling air to the conductor 1 from below the coil base 4, the bottom of the conductor 1 can be directly cooled through the through-hole in the conductor housing groove 4a. This makes it possible to suppress the rise in the conductor temperature of the conductor 1. By suppressing the rise in the conductor temperature of the conductor 1, the increase in the electrical resistance of the conductor 1 can be suppressed, and the decrease in the heating efficiency of the induction heating coil 100 can be suppressed.

[0027] Furthermore, while Figure 1 shows a configuration in which the conductor housing groove 4a and side wall 4b are provided along the circumferential direction for one full turn, that is, over 360 degrees from the central axis CL of the winding in the conductor portion 1, the conductor housing groove 4a and side wall may be provided only in a portion of the circumferential direction. Even in this case, since the conductor portion 1 can be housed by the conductor housing groove 4a and side wall 4b in at least a portion of the circumferential direction, distance between adjacent conductors can be secured, and contact between radially adjacent conductors that would otherwise cause a short circuit can be prevented. In addition, the volume of the coil base 4 can be reduced, thereby reducing the amount of material used to constitute the coil base 4, and enabling cost reduction and weight reduction of the induction heating coil 100.

[0028] The above is the description of the conductor part 1, the magnetic shielding ring 2, the magnetic member 3, and the coil base 4 that constitute the induction heating coil 100. Next, the details of the conductor part 1 will be described. As shown in FIG. 3, the conductor part 1 includes an inner peripheral conductor part 1c that includes the innermost peripheral surface 1i and is arranged on the inner peripheral side, an outer peripheral conductor part 1b that includes the outermost peripheral surface 1o and is arranged on the outer peripheral side, and an intermediate conductor part 1a that is arranged between the inner peripheral conductor part 1c and the outer peripheral conductor part 1b.

[0029] The conductor per one of the inner peripheral conductor part 1c has a radial width Wi and an axial height Ti. The conductor per one of the outer peripheral conductor part 1b has a radial width Wo and an axial height To. The conductor per one of the intermediate conductor part 1a has a radial width Wm and an axial height Tm.

[0030] When the radial distance Dci from the central axis CL to the innermost peripheral surface 1i and the radial distance Dmi from the central axis CL to the inner diameter side end 3a of the magnetic member 3 are defined for the conductor part 1 and the magnetic member 3, Dci ≦ Dmi and Wi < Ti are satisfied.

[0031] FIG. 4 is a cross-sectional view of the conductor per one of the conductor part 1. As shown in FIG. 4, a rounding R may be provided at the corner of the cross-section of the conductor part 1. Specifically, the inner peripheral conductor part 1c has a rounding R provided at the corner on the inner diameter side of the conductor. The outer peripheral conductor part 1b has a rounding R provided at the corner on the outer diameter side of the conductor. Note that, as shown in FIG. 4, the rounding R may be provided at all four locations of the cross-sectional corner part.

[0032] <Effect of the induction heating coil 100> The effect of the induction heating coil 100 according to Embodiment 1 will be described. FIG. 5 is a diagram schematically showing the flow of magnetic flux in the cross-section of the induction heating coil 100 according to Embodiment 1. FIG. 5 shows the flow of magnetic flux generated by passing a high-frequency current through the conductor part 1 by a broken-line arrow. Also, in FIG. 5, a cross-sectional view showing the positional relationship of the heated object 6, the conductor part 1, and the magnetic member 3 is shown.

[0033] As shown in Figure 5, the magnetic flux generated by passing a high-frequency current through the conductor 1 flows around the conductor 1 and through the inside of the heated object 6 and the magnetic member 3. In other words, a large amount of magnetic flux flows in and out from near the ends of the magnetic member 3 in the longitudinal direction.

[0034] Since the object to be heated 6 is made of metal or the like, when high-frequency magnetic flux links with the object to be heated 6, an induced electromotive force is generated based on Faraday's law of electromagnetic induction, and eddy currents are generated in the object to be heated 6. Due to these eddy currents and the electrical resistance of the object to be heated 6, Joule heat is generated, which is the power loss obtained by multiplying the square of the eddy current by the electrical resistance of the object to be heated 6. Here, Joule heat is the heat that contributes to heating the object to be heated 6.

[0035] At this time, a portion of the magnetic flux generated in the object being heated 6 simultaneously links with the conductor of the conductor part 1. In this case, an induced electromotive force is generated in the conductor of the conductor part 1, and eddy currents are generated in the conductor. Due to these eddy currents and the electrical resistance of the conductor of the conductor part 1, a Joule loss occurs, which is a power loss calculated by multiplying the square of the eddy current by the electrical resistance of the conductor part 1. Since this Joule loss is a power loss in the conductor part 1, it does not contribute to the heating of the object being heated 6 and becomes a factor that reduces heating efficiency.

[0036] As shown in Figure 5, a large amount of magnetic flux is generated flowing from the end of the magnetic member 3 into the object to be heated 6, or from the object to be heated 6 into the end of the magnetic member 3. Therefore, the inner and outer conductors located near the end of the magnetic member 3 are linked with a large amount of magnetic flux flowing in or out near the end of the magnetic member 3, making these areas prone to Joule loss. This causes a decrease in heating efficiency. Due to this phenomenon, the Joule loss generated in the conductor portion 1 tends to increase the closer it is to the end of the magnetic member 3.

[0037] Therefore, in the induction heating coil 100 according to Embodiment 1, when the radial distance Dci from the central axis CL to the innermost peripheral surface 1i of the inner peripheral conductor portion 1c and the radial distance Dmi from the central axis CL to the inner diameter side end portion 3a of the magnetic member 3 are considered, it is configured to satisfy Dci ≤ Dmi and Wi < Ti. According to this configuration, the spatial distance between adjacent conductors can be increased without reducing the conductor cross-sectional area of the conductor portion 1. When the conductor cross-sectional area of the conductor portion 1 becomes smaller, the electrical resistance of the conductor portion 1 increases, resulting in an increase in Joule loss. However, since the induction heating coil 100 according to Embodiment 1 does not reduce the conductor cross-sectional area of the conductor portion 1, an increase in Joule loss generated in the conductor portion 1 can be suppressed.

[0038] Also, by being configured such that Wi < Ti, the spatial distance between adjacent conductors can be increased without reducing the conductor cross-sectional area of the conductor portion 1. Therefore, the magnetic flux linkage to the conductor portion 1 can be reduced with respect to the magnetic flux flowing axially from the heated object 6 to the end portion of the magnetic member 3 or the magnetic flux flowing axially from the end portion of the magnetic member 3 to the heated object 6. As a result, the Joule loss of the inner peripheral side conductor located at the end portion of the magnetic member 3 can be reduced, so that the Joule loss generated in the inner peripheral conductor portion 1c can be reduced, and the heating efficiency of the induction heating coil 100 can be improved.

[0039] As shown in FIG. 1, the magnetic member 3 is arranged radially from the central axis CL of the winding of the conductor portion 1 below the coil base 4 from the inner peripheral side to the outer peripheral side of the conductor portion 1. That is, the magnetic member 3 is denser on the inner peripheral side than on the outer peripheral side of the conductor portion 1. From this, since the magnetic flux is more likely to concentrate on the inner peripheral side than on the outer peripheral side of the magnetic member 3, the eddy current generated in the inner peripheral conductor portion 1c in the conductor portion 1 tends to increase.

[0040] Therefore, by configuring such that Dci ≦ Dmi and Wi < Ti, the axial magnetic flux flowing between the inner diameter side end portion 3a of the magnetic member 3 and the object to be heated 6 can be made to flow into the wide space between adjacent conductors. As a result, the magnetic flux interlinking with the conductors of the inner peripheral conductor portion 1c can be reduced, so that the Joule loss generated in the inner peripheral conductor portion 1c can be reduced. Further, by setting Dci ≦ Dmi, the concentration of the plurality of magnetic members 3 in the vicinity of the central axis CL can be suppressed. When the magnetic members 3 are concentrated in the vicinity of the central axis CL, the magnetic members 3 interfere with each other, so that a large number of magnetic members 3 cannot be arranged, and it is necessary to make the magnetic members 3 thinner or reduce the number of magnetic members 3. In this case, the magnetic flux cannot be efficiently induced in the object to be heated 6. Therefore, by setting Dci ≦ Dmi, the concentration of the plurality of magnetic members 3 in the vicinity of the central axis CL can be suppressed, and the magnetic flux can be efficiently induced from the magnetic members 3 toward the object to be heated 6. Due to the above effects, the heating efficiency of the induction heating coil 100 can be improved.

[0041] Further, as shown in FIG. 4, by providing a rounding R at the corner of the conductor cross section of the conductor portion 1, the Joule loss generated in the conductor portion 1 can be further suppressed. This effect will be described.

[0042] In FIG. 4, regarding the magnetic flux circulating around the conductor of the conductor portion 1 according to the first embodiment, a part of the conductor and the magnetic flux are enlarged, and the flow of the magnetic flux is schematically shown. The conductor 1s provided with the rounding R and the conductor 1r having an edge without providing the rounding R at the cross-sectional corner portion for comparison, that is, the conductor 1r with R = 0, are superimposed and shown, and the flow of the surrounding magnetic flux is indicated by a broken line arrow.

[0043] As shown in FIG. 4, at the cross-sectional corner portion of the conductor, in the conductor 1s provided with the rounding R, compared with the conductor 1r not provided with the rounding R, the interlinking magnetic flux at the cross-sectional corner portion is reduced. In other words, in the conductor 1r not provided with the rounding R, the magnetic flux easily interlinks at the cross-sectional corner portion, and local eddy current loss occurs at the cross-sectional corner portion. Therefore, by providing the rounding R, the local eddy current generated at the cross-sectional corner portion of the conductor 1s can be reduced.

[0044] Note that in Figure 4, rounded edges (R) are provided at all four corners of the cross-section of conductor 1s, but the number of rounded edges (R) is not limited to four. Figure 6 is a cross-sectional view of a single conductor in the inner circumference conductor portion 1c of conductor portion 1. Figure 7 is a cross-sectional view of a single conductor in the outer circumference conductor portion 1b of conductor portion 1. As shown in Figures 6 and 7, for example, rounded edges (R) may be provided at only two locations on one side of the cross-section, depending on the flow of magnetic flux.

[0045] Specifically, as shown in Figure 6, it is desirable that the inner circumferential conductor portion 1c has rounded corners on the inner diameter side of the conductor. Also, as shown in Figure 7, it is desirable that the outer circumferential conductor portion 1b has rounded corners on the outer diameter side of the conductor. Even in this case, local eddy currents generated at the cross-sectional corners of the conductor can be reduced. Furthermore, by having corners without rounded corners, the conductor cross-sectional area can be increased, thereby reducing the electrical resistance of the conductor portion 1 and reducing the Joule loss generated in the conductor portion 1, thus improving the heating efficiency of the induction heating coil 100.

[0046] The induction heating coil 100 according to Embodiment 1 can widen the distance between adjacent conductors even while ensuring the desired conductor cross-sectional area, compared to, for example, a single wire with a perfectly circular cross-sectional shape. This effectively reduces Joule loss, particularly in the inner circumferential conductor located near the inner diameter end 3a of the magnetic member 3.

[0047] Furthermore, the induction heating coil 100 according to Embodiment 1 can suppress an increase in Joule loss in the conductor portion 1 even when the length of the inner circumference side in the longitudinal direction of the magnetic member 3 is short, thereby reducing the amount of magnetic member 3 used. This makes it possible to construct a lightweight and low-cost induction heating coil 100.

[0048] In addition, in Embodiment 1, by using a rectangular wire for the conductor portion 1, the conductor portion 1 with a cross-sectional shape of Wi < Ti can be easily realized. Further, since the rectangular wire is a single wire composed of a single conductor wire, compared with Litz wire, the cross-sectional area occupied by the insulating coating with low thermal conductivity is reduced, so that the thermal conductivity of the conductor portion 1 can be improved particularly in the radial direction. Thus, by using a rectangular wire for the conductor portion 1, the thermal conductivity of the conductor portion 1 can be improved, so that even when cooled by cooling air from below the induction heating coil 100, the cooling air can be easily transmitted sufficiently inside the conductor portion 1, and the cooling performance of the conductor portion 1 can be improved.

[0049] Furthermore, the conductor portion 1 can also be made of aluminum. Compared with copper, aluminum has a small weight density and is easy to procure. Therefore, by using aluminum for the conductor portion 1, a lightweight and low-cost induction heating coil 100 can be configured.

[0050] Modification 1. <Configuration of Induction Heating Coil 100a> The configuration of the induction heating coil 100a according to Modification 1 will be described. FIG. 8 is a cross-sectional view of the induction heating coil 100a according to Modification 1. Each configuration of the induction heating coil 100a according to Modification 1 is the same as or equivalent to the induction heating coil 100 according to Embodiment 1 except for the conductor portion 1 and the magnetic member 3. Therefore, the description of the portions having the same configuration as the induction heating coil 100 according to Embodiment 1 will be omitted.

[0051] As shown in FIG. 8, when the radial distance Dco from the central axis CL to the outermost peripheral surface 1o of the outer peripheral conductor portion 1b and the radial distance Dmo from the central axis CL to the outer diameter side end portion 3b of the magnetic member 3 are considered, Dco ≧ Dmo and Wo < To are satisfied.

[0052] <Effect of Induction Heating Coil 100a> The effect of the induction heating coil 100a according to the first modification will be described. According to this configuration, the spatial distance between adjacent conductors can be increased without reducing the conductor cross-sectional area of the conductor portion 1. When the conductor cross-sectional area of the conductor portion 1 is reduced, the electrical resistance of the conductor portion 1 increases, resulting in an increase in Joule loss. However, since the induction heating coil 100a according to the first modification does not reduce the conductor cross-sectional area of the conductor portion 1, an increase in Joule loss generated in the conductor portion 1 can be suppressed.

[0053] Further, by being configured such that Wo < To, the spatial distance between adjacent conductors can be increased without reducing the conductor cross-sectional area of the conductor portion 1. Therefore, the magnetic flux linkage to the conductor portion 1 with respect to the magnetic flux flowing axially from the heated object 6 to the end of the magnetic member 3 or the magnetic flux flowing axially from the end of the magnetic member 3 to the heated object 6 can be reduced. As a result, the loss of the conductor portion 1 on the outer peripheral side located at the end of the magnetic member 3 can be reduced, so that the Joule loss generated in the outer peripheral conductor portion 1b can be reduced and the heating efficiency can be improved.

[0054] Also, by being configured such that Dco ≥ Dmo and Wo < To, an axial magnetic flux can flow between the outer diameter side end portion 3b of the magnetic member 3 and the object to be heated 6 in a wide space between adjacent conductors. Thereby, the Joule loss generated in the outer peripheral conductor portion 1b can be reduced. Also, by setting Dco ≥ Dmo, the distance between the magnetic member 3 and the magnetic shielding ring 2 can be increased. Since the magnetic shielding ring 2 is made of a conductor such as aluminum, when the magnetic flux from the outer diameter side end portion 3b of the magnetic member 3 toward the object to be heated 6 intersects the magnetic shielding ring 2, an eddy current is generated in the magnetic shielding ring 2. Due to this eddy current, Joule loss occurs in the magnetic shielding ring 2. Here, the Joule loss is the power loss in the magnetic shielding ring 2, so it does not contribute to the heating of the object to be heated 6 and becomes a factor that reduces the heating efficiency. Therefore, by setting Dco ≥ Dmo, the distance between the outer diameter side end portion 3b of the magnetic member 3 and the magnetic shielding ring 2 can be increased, so that the magnetic flux can easily flow from the outer diameter side end portion 3b of the magnetic member 3 to the object to be heated 6. As a result, the magnetic flux intersecting the magnetic shielding ring 2 can be reduced, and the Joule loss generated in the magnetic shielding ring 2 can be reduced. Due to the above effects, the heating efficiency of the induction heating coil 100a can be improved.

[0055] Modification 2. <Configuration of the induction heating coil 100b> The configuration of the induction heating coil 100b according to Modification 2 will be described. FIG. 9 is a cross-sectional view of the induction heating coil 100b according to Modification 2. Each configuration of the induction heating coil 100b according to Modification 2 is the same as or equivalent to that of the induction heating coil 100 according to Embodiment 1, except for the conductor portion 1 and the magnetic member 3. Therefore, the description of the portions having the same configuration as the induction heating coil 100 according to Embodiment 1 will be omitted.

[0056] As shown in FIG. 9, when the radial distances are defined as follows: the radial distance Dci from the central axis CL to the innermost peripheral surface 1i of the inner peripheral conductor portion 1c, the radial distance Dco from the central axis CL to the outermost peripheral surface 1o of the outer peripheral conductor portion 1b, the radial distance Dmi from the central axis CL to the inner diameter side end portion 3a of the magnetic member 3, and the radial distance Dmo from the central axis CL to the outer diameter side end portion 3b of the magnetic member 3, Dci ≦ Dmi and Wi < Ti, and Dco ≧ Dmo and Wo < To are satisfied.

[0057] <Effect of the induction heating coil 100b> The effect of the induction heating coil 100b according to the second modification will be described. According to this configuration, the spatial distance between adjacent conductors can be increased without reducing the conductor cross-sectional area of the conductor portion 1. When the conductor cross-sectional area of the conductor portion 1 is reduced, the electrical resistance of the conductor portion 1 increases, resulting in an increase in joule loss. However, since the induction heating coil 100b according to the second modification does not reduce the conductor cross-sectional area of the conductor portion 1, an increase in joule loss generated in the conductor portion 1 can be suppressed.

[0058] In addition, by being configured such that Wi < Ti and Wo < To, the spatial distance between adjacent conductors can be increased without reducing the conductor cross-sectional area of the conductor portion 1. Therefore, the magnetic flux linked to the conductor portion 1 with respect to the magnetic flux flowing axially from the heated object 6 to the end portion of the magnetic member 3 or the magnetic flux flowing axially from the end portion of the magnetic member 3 to the heated object 6 can be reduced. As a result, the joule loss of the inner peripheral side conductor and the outer peripheral side conductor located at the end portion of the magnetic member 3 can be reduced, so that the joule loss generated in the inner peripheral conductor portion 1c and the outer peripheral conductor portion 1b can be reduced, and the heating efficiency can be improved.

[0059] Further, by being configured such that Dci ≦ Dmi and Wi < Ti, and Dco ≧ Dmo and Wo < To, the axial magnetic flux flowing between the inner diameter side end portion 3a of the magnetic member 3 and the object to be heated 6, and the axial magnetic flux flowing between the outer diameter side end portion 3b of the magnetic member 3 and the object to be heated 6 can be made to flow into the wide space between adjacent conductors. Thereby, the Joule loss generated in the inner peripheral conductor portion 1c and the outer peripheral conductor portion 1b can be reduced. Also, by setting Dci ≦ Dmi and Dco ≧ Dmo, the same effects as those of the induction heating coil 100 described in Embodiment 1 and the induction heating coil 100a described in Modified Example 1 can be obtained. That is, it is possible to suppress the concentration of the plurality of magnetic members 3 near the central axis CL and efficiently induce magnetic flux from the magnetic member 3 toward the object to be heated 6. Further, since the distance between the outer diameter side end portion 3b of the magnetic member 3 and the magnetic shielding ring 2 can be increased, magnetic flux easily flows from the outer diameter side end portion 3b of the magnetic member 3 to the object to be heated 6. As a result, the magnetic flux interlinking with the magnetic shielding ring 2 can be reduced, and the Joule loss generated in the magnetic shielding ring 2 can be reduced. Due to the above effects, the heating efficiency of the induction heating coil 100b can be improved.

[0060] Embodiment 2. <Configuration of Induction Heating Coil 110> The configuration of the induction heating coil 110 according to Embodiment 2 will be described. FIG. 10 is a cross-sectional view of the induction heating coil 110 according to Embodiment 2. Each configuration of the induction heating coil 110 according to Embodiment 2 is the same as or equivalent to that of the induction heating coil 100 according to Embodiment 1, except for the conductor portion 1 and the coil base 4. Therefore, description of the portions having the same configuration as those of the induction heating coil 100 according to Embodiment 1 will be omitted.

[0061] As shown in FIG. 10, in the conductor portion 1 according to Embodiment 2, when the radial distance Xm between adjacent conductors of the intermediate conductor portion 1a, the radial distance Xi between adjacent conductors of the inner peripheral conductor portion 1c, and the radial distance Xo between adjacent conductors of the outer peripheral conductor portion 1b are considered, at least one of Xm < Xi or Xm < Xo is satisfied.

[0062] In FIG. 10, the side wall portion 4b of the intermediate conductor portion 1a is thinner than the side wall portions 4b of the inner peripheral conductor portion 1c and the outer peripheral conductor portion 1b by the amount by which the radial distance Xm of the intermediate conductor portion 1a is narrowed.

[0063] FIG. 11 is a cross-sectional view of the induction heating coil 110 that satisfies only Xm < Xi in the induction heating coil 110 according to Embodiment 2. As shown in FIG. 11, it may be configured to satisfy only Xm < Xi.

[0064] FIG. 12 is a cross-sectional view of the induction heating coil 110 that satisfies only Xm < Xo in the induction heating coil 110 according to Embodiment 2. As shown in FIG. 1, it may be configured to satisfy only Xm < Xo.

[0065] Also, when the number of turns Nm of the intermediate conductor portion 1a, the number of turns Ni of the inner peripheral conductor portion 1c, and the number of turns No of the outer peripheral conductor portion 1b are considered, Nm > Ni or Nm > No. For example, in FIG. 10, the number of turns Nm of the intermediate conductor portion 1a is 9, the number of turns Ni of the inner peripheral conductor portion 1c is 6, and the number of turns No of the outer peripheral conductor portion 1b is 2, and the total number of turns of the induction heating coil 110 is 17 turns. Since the number of turns of the induction heating coil 100 according to Embodiment 1 is 15 turns, the induction heating coil 110 has an increase of 2 turns. Note that the above number of turns is merely an example, and the number of turns is not limited to the above.

[0066] Also, as shown in FIGS. 10 to 12, when the number of turns Ni of the inner peripheral conductor portion 1c and the number of turns No of the outer peripheral conductor portion 1b are considered, it is desirable that Ni > No. The reason for this will be described later.

[0067] <Effect of the induction heating coil 110> <00002… The effect of the induction heating coil 110 according to Embodiment 2 will be described. FIG. 13 is a diagram schematically showing the flow of magnetic flux in the cross section of the induction heating coil 110 according to Embodiment 2. In FIG. 13, the flow of magnetic flux generated by passing a high-frequency current through the conductor portion 1 is indicated by a dashed arrow. Also, in FIG. 13, a cross-sectional view showing the positional relationship of the heated object 6, the conductor portion 1, and the magnetic member 3 is shown.

[0068] As shown in Figure 13, the combined magnetic flux generated by the conductor portion 1 is generated in a large ellipse, flowing between the inner circumference conductor portion 1c and the outer circumference conductor portion 1b of the conductor portion 1. Therefore, a large amount of magnetic flux links between the inner circumference conductor portion 1c and the outer circumference conductor portion 1b of the conductor portion 1. Consequently, by ensuring a distance between adjacent conductors in the radial direction, the proximity effect can be suppressed, and eddy current losses generated in the conductor portion 1 can be reduced. Up to this point, it is the same as the induction heating coil 100 according to Embodiment 1.

[0069] On the other hand, the intermediate conductor portion 1a of the conductor portion 1 has a sufficient distance from the inner diameter end 3a and outer diameter end 3b of the magnetic member 3, resulting in less axial magnetic flux linking between the magnetic member 3 and the object to be heated 6. In other words, the intermediate conductor portion 1a is less affected by the magnetic flux generated from the inner diameter end 3a and outer diameter end 3b of the magnetic member 3. Therefore, as in the induction heating coil 110 according to Embodiment 2, the radial distance Xm between adjacent conductors can be reduced only in the intermediate conductor portion 1a compared to the radial distance Xi between adjacent conductors in the inner circumference conductor portion 1c or the radial distance Xo between adjacent conductors in the outer circumference conductor portion 1b. This makes it possible to suppress eddy currents generated in the conductor portion 1 and Joule losses generated in the conductor portion 1 while increasing the total number of turns of the induction heating coil 110.

[0070] By increasing the total number of turns of the induction heating coil 110, the inductance of the induction heating coil 110 can be increased. Since the magnetic flux flowing into the object to be heated 6 is proportional to the inductance, when a high-frequency current with the same frequency and amplitude is passed through the induction heating coil 110, the higher the inductance of the induction heating coil 110, the greater the amount of magnetic flux flowing into the object to be heated 6. As a result, the amount of heat generated by the object to be heated 6 increases, and the heating efficiency of the induction heating coil 110 can be improved.

[0071] Furthermore, if the number of turns of the inner conductor portion 1c is Ni and the number of turns of the outer conductor portion 1b is No, it is desirable that Ni > No. The reason for this will be explained. As shown in Figure 1, the magnetic members 3 are arranged radially from the central axis CL of the conductor portion 1, from the inner side to the outer side, below the coil base 4. In other words, the magnetic members 3 are more densely packed on the inner side of the conductor portion 1 than on the outer side.

[0072] As shown in Figure 13, the magnetic flux generated by passing a high-frequency current through the conductor 1 flows inside the heated object 6 and the magnetic member 3, circulating around the conductor 1. At this time, a large amount of magnetic flux flows in and out from near the inner diameter end 3a and the outer diameter end 3b of the magnetic member 3. Furthermore, since the magnetic member 3 is more densely packed on the inner circumference side of the conductor 1 than on the outer circumference side, a larger amount of magnetic flux flows in and out on the inner circumference side of the conductor 1 compared to the outer circumference side.

[0073] This means that the magnetic flux linked to the conductors of the conductor part 1 is greater on the inner circumference side than on the outer circumference side, and the influence of eddy currents generated in the conductors becomes more pronounced. In other words, on the inner circumference side of the conductor part 1, which is susceptible to the influence of magnetic flux, it is desirable to increase the distance between conductors to reduce the magnetic flux linked to the conductor part 1.

[0074] Therefore, in the induction heating coil 110 according to Embodiment 2, when the number of turns of the inner conductor portion 1c is Ni and the number of turns of the outer conductor portion 1b is No, the intermediate conductor portion 1a can be moved closer to the outer circumference of the conductor portion 1. By moving the intermediate conductor portion 1a closer to the outer circumference, which is less affected by the magnetic flux linking between the object to be heated 6 and the magnetic member 3, the influence of eddy currents generated in the conductor portion 1 can be suppressed, while the total number of turns of the induction heating coil 110 can be increased, and the inductance can be increased. As a result, the amount of heat generated by the object to be heated 6 can be increased, and the heating efficiency of the induction heating coil 110 can be improved.

[0075] Embodiment 3. <Configuration of induction heating coil 120> The configuration of the induction heating coil 120 according to Embodiment 3 will now be described. Figure 14 is a cross-sectional view of the induction heating coil 120 according to Embodiment 3. Each component of the induction heating coil 120 according to Embodiment 3 is the same as or equivalent to that of the induction heating coil 100 according to Embodiment 1, except for the conductor portion 1 and the coil base 4. Therefore, the parts that have the same configuration as the induction heating coil 100 according to Embodiment 1 will not be described.

[0076] As shown in Figure 14, the conductor portion 1 according to Embodiment 3 satisfies at least one of Wm > Wi or Wm > Wo, where Wm is the radial width of each conductor in the intermediate conductor portion 1a, Wi is the radial width of each conductor in the inner circumferential conductor portion 1c, and Wo is the radial width of each conductor in the outer circumferential conductor portion 1b.

[0077] In Figure 14, the radial width Wm of each conductor in the intermediate conductor section 1a is increased, so the side wall 4b of the intermediate conductor section 1a is thinner than the side wall 4b of the inner conductor section 1c and the outer conductor section 1b.

[0078] Figure 15 is a cross-sectional view of the induction heating coil 120 according to Embodiment 3, where only Wm > Wi is satisfied. As shown in Figure 15, it may be configured to satisfy only Wm > Wi.

[0079] Figure 16 is a cross-sectional view of the induction heating coil 120 according to Embodiment 3, where only Wm > Wo is satisfied. As shown in Figure 16, it may be configured to satisfy only Wm > Wo.

[0080] The inner conductor portion 1c and the intermediate conductor portion 1a, and the intermediate conductor portion 1a and the outer conductor portion 1b are electrically connected, although not shown in the diagram. The connection method may be, for example, soldering or crimping.

[0081] <Effects of induction heating coil 120> The effects of the induction heating coil 120 according to Embodiment 3 will be explained. Figure 17 is a schematic diagram showing the flow of magnetic flux in a cross-section of the induction heating coil 120 according to Embodiment 3. In Figure 11, the flow of magnetic flux generated by passing a high-frequency current through the conductor part 1 is shown by dashed arrows. Figure 17 is a cross-sectional view showing the positional relationship between the object to be heated 6, the conductor part 1, and the magnetic member 3.

[0082] As shown in Figure 17, the combined magnetic flux generated by the conductor portion 1 is generated in a large ellipse, flowing between the inner circumference conductor portion 1c and the outer circumference conductor portion 1b of the conductor portion 1. Therefore, a large amount of magnetic flux links between the inner circumference conductor portion 1c and the outer circumference conductor portion 1b of the conductor portion 1. Consequently, by ensuring a distance between adjacent conductors in the radial direction, the proximity effect can be suppressed, and eddy current losses in the conductors can be reduced. Up to this point, it is the same as the induction heating coil 100 according to Embodiment 1.

[0083] On the other hand, the intermediate conductor portion 1a of the conductor portion 1 has a sufficient distance from the inner diameter end 3a and outer diameter end 3b of the magnetic member 3, resulting in less axial magnetic flux linking between the magnetic member 3 and the object to be heated 6. In other words, the intermediate conductor portion 1a is less affected by the magnetic flux generated from the inner diameter end 3a and outer diameter end 3b of the magnetic member 3. Therefore, as in the induction heating coil 120 according to Embodiment 3, if the radial width of each conductor in the intermediate conductor portion 1a is Wm, the radial width of each conductor in the inner circumference conductor portion 1c is Wi, and the radial width of each conductor in the outer circumference conductor portion 1b is Wo, then by configuring it so that Wm > Wi or Wm > Wo holds true, the cross-sectional area of ​​each conductor in the intermediate conductor portion 1a can be increased. This suppresses eddy currents generated in the conductors of the conductor portion 1 while reducing the electrical resistance of the conductor portion 1, thereby reducing Joule losses generated in the conductor portion 1 and improving the heating efficiency of the induction heating coil 120.

[0084] Embodiment 4. <Configuration of induction heating coil 130> The configuration of the induction heating coil 130 according to Embodiment 4 will now be described. Figure 18 is a cross-sectional view of the induction heating coil 130 according to Embodiment 4. Each component of the induction heating coil 130 according to Embodiment 4 is the same as or equivalent to that of the induction heating coil 100 according to Embodiment 1, except for the conductor portion 1 and the coil base 4. Therefore, the parts that have the same configuration as the induction heating coil 100 according to Embodiment 1 will not be described.

[0085] As shown in Figure 18, in the conductor section 1 according to Embodiment 4, when Wm is the radial width of each conductor in the intermediate conductor section 1a and Tm is the axial height of each conductor in the intermediate conductor section 1a, Wm > Tm. In this case, since heating efficiency can be improved by keeping the axial distance between the intermediate conductor section 1a and the object to be heated 6 short, it is desirable that each conductor in the intermediate conductor section 1a be positioned upward in the axial direction.

[0086] In Figure 18, the radial width Wm of each conductor in the intermediate conductor section 1a is increased, so the side wall 4b of the intermediate conductor section 1a is thinner than the side wall 4b of the inner conductor section 1c and the outer conductor section 1b.

[0087] Figure 19 is a perspective view showing an example of the configuration of the conductor portion 1 of the induction heating coil 130 according to Embodiment 4. Figure 19 is an example of realizing the conductor portion 1 according to Embodiment 4 with a single continuous conductor. As shown in Figure 19, it has a first transition portion 1d that transitions from the inner circumferential conductor portion 1c to the intermediate conductor portion 1a, and a second transition portion 1e that transitions from the intermediate conductor portion 1a to the outer circumferential conductor portion 1b. Furthermore, the first transition portion 1d and the second transition portion 1e are configured to be twisted 90 degrees in the radial direction.

[0088] <Effects of induction heating coil 130> The effects of the induction heating coil 130 according to Embodiment 4 will be explained. Figure 20 is a schematic diagram showing the flow of magnetic flux in a cross-section of the induction heating coil 130 according to Embodiment 4. In Figure 14, the flow of magnetic flux generated by passing a high-frequency current through the conductor part 1 is shown by dashed arrows. Figure 20 is a cross-sectional view showing the positional relationship between the object to be heated 6, the conductor part 1, and the magnetic member 3.

[0089] As shown in Figure 20, the combined magnetic flux generated by the conductor portion 1 is generated in a large ellipse, flowing between the inner circumference conductor portion 1c and the outer circumference conductor portion 1b of the conductor portion 1. Therefore, a large amount of magnetic flux links between the inner circumference conductor portion 1c and the outer circumference conductor portion 1b of the conductor portion 1. Consequently, by ensuring a distance between adjacent conductors in the radial direction, the proximity effect can be suppressed, and eddy current losses generated in the conductor portion 1 can be reduced. Up to this point, it is the same as the induction heating coil 100 according to Embodiment 1.

[0090] On the other hand, the intermediate conductor portion 1a of the conductor portion 1 has a sufficient distance from the inner diameter end 3a and outer diameter end 3b of the magnetic member 3, resulting in less axial magnetic flux linking between the magnetic member 3 and the object to be heated 6. In other words, the intermediate conductor portion 1a is less affected by the magnetic flux generated from the inner diameter end 3a and outer diameter end 3b of the magnetic member 3. Therefore, as in the induction heating coil 130 according to Embodiment 4, by configuring each conductor of the intermediate conductor portion 1a such that Wm > Tm holds true, where Wm is the radial width and Tm is the axial height, the magnetic flux linking to the conductor portion 1 is reduced, and the Joule loss of the conductor portion 1 is reduced, thereby improving the heating efficiency.

[0091] Specifically, near the intermediate conductor section 1a, magnetic flux flows radially through the magnetic member 3 or the object being heated 6. As a result, the axial magnetic flux flowing from the object being heated 6 towards the magnetic member 3 or from the magnetic member 3 towards the object being heated 6 is small, and the radially flowing magnetic flux becomes dominant. In addition, some of the magnetic flux flows radially as leakage flux in the space other than the magnetic member 3. In this case, as the axial height Tm of each conductor in the intermediate conductor section 1a increases, the radial magnetic flux linked to the conductors of the intermediate conductor section 1a increases. This increases the eddy currents in the conductors of the intermediate conductor section 1a, and the Joule loss generated in the conductor section 1 increases.

[0092] Here, even if the radial width Wm of each conductor in the intermediate conductor section 1a increases, the magnetic flux linked to the conductors in the intermediate conductor section 1a remains small. Therefore, in the intermediate conductor section 1a, by configuring it so that Wm > Tm holds true when the radial width Wm and axial height Tm of each conductor are given, the magnetic flux linked to the conductors in the intermediate conductor section 1a is reduced. This reduces the eddy currents generated in the conductors of the intermediate conductor section 1a, thereby reducing the Joule loss of the conductor section 1 and improving the heating efficiency of the induction heating coil 130.

[0093] Furthermore, as shown in Figure 19, the conductor section 1 is composed of a single continuous conductor and has a first transition section 1d that transitions from the inner circumference conductor section 1c to the intermediate conductor section 1a, and a second transition section 1e that transitions from the intermediate conductor section 1a to the outer circumference conductor section 1b. In addition, the first transition section 1d and the second transition section 1e are configured to be twisted 90 degrees in the radial direction. This eliminates the need to connect the conductors with connecting members or the like, compared to the case where different conductors are used in combination for the inner circumference conductor section 1c, the outer circumference conductor section 1b, and the intermediate conductor section 1a. In other words, since the conductor section 1 can be formed with a single conductor, the assembly process of the conductor section 1 can be simplified. Furthermore, since the contact resistance that would otherwise be generated by using connecting members is eliminated, the increase in the electrical resistance of the conductor section 1 due to contact resistance is suppressed, the increase in Joule loss generated in the conductor section 1 is suppressed, and the decrease in the heating efficiency of the induction heating coil 130 can be suppressed.

[0094] The material and shape of the conductor part 1 are not particularly limited, but it is preferable to construct the conductor part 1 using, for example, flat aluminum wire. Since aluminum is softer than copper, in the assembly process in which the first transition part 1d and the second transition part 1e are provided to the conductor part 1, it becomes easier to process the conductor part 1 to twist it 90 degrees radially, thereby improving the productivity of the conductor part 1.

[0095] Embodiment 5. <Configuration of induction cooker 200> The configuration of the induction heating cooker 200 according to Embodiment 5 will be explained using Figure 2. As shown in Figure 2, the induction heating cooker 200 according to Embodiment 5 includes an induction heating coil, a housing 8, a top plate 9, an inverter board 7, an operation unit 10, a display unit 11, and a cooling fan (not shown) that supplies cooling air from outside the housing 8 to the inside of the housing 8. The induction heating coil is one of the induction heating coils 100, 100a, 100b, 110, 120, or 130 described in Embodiments 1-4.

[0096] The housing 8 houses the induction heating coils 100, 100a, 100b, 110, 120, and 130, the inverter board 7, the operation unit 10, the display unit 11, lead wires (not shown), and connectors (not shown).

[0097] The top plate 9 is a plate on which the object to be heated 6 is placed, and is made of a non-metallic material such as heat-resistant glass or ceramic. As shown in Figure 2, two circular heating ports are provided on the top plate 9, and one of the induction heating coils 100, 100a, 100b, 110, 120, or 130 is provided in each of the two heating ports. The number of heating ports is not limited to two; there may be one or three or more. Also, the shape of the heating ports is not limited to circles; for example, they may be square or other shapes.

[0098] The inverter board 7 includes a rectifier circuit (not shown) that converts AC power to DC, and an inverter circuit (not shown) that generates a high-frequency current from the DC and energizes the induction heating coils 100, 100a, 100b, 110, 120, and 130. The configuration of the inverter circuit is not particularly limited, but is a known electrical circuit such as a half-bridge inverter, a full-bridge inverter, or a single-transistor voltage resonant inverter, and is composed of switching elements such as IGBTs or MOSFETs.

[0099] The control unit 10 is for the user to adjust the heat output of the induction cooker 200. The control unit 10 is an input device such as a touch panel that receives input regarding heating conditions such as heating temperature or heating time, and operation commands such as starting or stopping heating. The arrangement and structure of the control unit 10 are not limited to the example shown in Figure 2, and may be a dial type, a tact switch type, or a voice input type, for example. Also, although Figure 2 shows an example in which the control unit 10 is provided on the housing 8, the control unit 10 may be provided on the front of the top plate 9 in addition to or instead of the housing 8.

[0100] The display unit 11 notifies the user of the heating power and elapsed heating time, etc. The display unit 11 displays whether heating is in progress at the heating port, the set temperature and heating mode, the timer, and warning information for the user. The display unit 11 is, for example, a liquid crystal display. The arrangement and structure of the display unit 11 are not limited to the example shown in Figure 2, and may be, for example, a 7-segment LED (Light Emitting Diode). Also, although Figure 2 shows an example in which the display unit 11 is provided on the housing 8, the display unit 11 may be provided on the front of the top plate 9 in addition to or instead of the housing 8.

[0101] Figure 21 is a cross-sectional view of an induction cooker 200 according to Embodiment 5. The conductor portion 1 satisfies at least one of Gm = Gi or Gm = Go, where Gm is the axial distance between the intermediate conductor portion 1a and the top plate 9, Gi is the axial distance between the inner circumferential conductor portion 1c and the top plate 9, and Go is the axial distance between the outer circumferential conductor portion 1b and the top plate 9.

[0102] Figure 22 is a cross-sectional view of the induction cooker 200 according to Embodiment 5, where only Gm=Gi is satisfied. As shown in Figure 22, it may be configured to satisfy only Gm=Gi.

[0103] Figure 23 is a cross-sectional view of the induction cooker 200 according to Embodiment 5, which satisfies only Gm=Go. As shown in Figure 23, it may be configured to satisfy only Gm=Go.

[0104] <Operation of induction cooker 200> The operation of the induction heating cooker 200 according to Embodiment 5 will now be described. Since the induction heating coils 100, 100a, 100b, 110, 120, and 130 are connected to the inverter board 7, a high-frequency current is supplied from the inverter board 7 to the induction heating coils 100, 100a, 100b, 110, 120, and 130, generating a high-frequency magnetic flux in the object to be heated 6 placed on the top plate 9. This high-frequency magnetic flux generates eddy currents in the object to be heated 6, and these eddy currents heat the object to be heated 6. A cooling fan (not shown) blows air to cool the inverter board and the induction heating coils 100, 100a, 100b, 110, 120, and 130 by blowing air over the heat generated in the inverter board and the induction heating coils 100, 100a, 100b, 110, 120, and 130.

[0105] <Effects of induction cooker 200> The effects of the induction heating cooker 200 according to Embodiment 5 will now be explained. In the induction heating cooker 200 according to Embodiment 5, the induction heating coils 100, 100a, 100b, 110, 120, and 130 described in Embodiments 1-4 are applied, so the same advantages as those described in Embodiments 1-4 can be obtained. As a result, an induction heating cooker 200 with improved heating efficiency can be provided.

[0106] Furthermore, as shown in Figure 21, when the conductor section 1 has an axial distance Gm between the intermediate conductor section 1a and the top plate 9, an axial distance Gi between the inner circumference conductor section 1c and the top plate 9, and an axial distance Go between the outer circumference conductor section 1b and the top plate 9, it is desirable that at least one of Gm=Gi or Gm=Go is satisfied. This ensures that the axial distance between the conductor section 1 and the object to be heated 6 remains constant throughout the entire conductor section 1, thereby suppressing uneven heating of the object to be heated 6 and allowing the object to be heated 6 to be heated evenly. While uneven heating can be suppressed by satisfying at least one of Gm=Gi or Gm=Go, as shown in Figure 21, the effect of suppressing uneven heating can be enhanced by satisfying Gm=Gi=Go.

[0107] Furthermore, while embodiments of the induction heating coils 100, 100a, 100b, 110, 120, 130 and the induction heating cooker 200 of this disclosure have been described, this disclosure is not limited to the above embodiments, and various modifications or combinations are possible without departing from the spirit of this disclosure.

[0108] The various embodiments of the induction heating coils 100, 100a, 100b, 110, 120, 130 and the induction heating cooker 200 of this disclosure are described below as an appendix.

[0109] (Note 1) A conductive part consisting of a conductor wound around a central axis, The magnetic member is arranged along the radial direction of the conductor portion and has an inner diameter end face which is the inner diameter end face and an outer diameter end face which is the outer diameter end face, The conductor portion comprises an inner circumferential conductor portion that includes the innermost circumferential surface and is arranged on the inner circumferential side, an outer circumferential conductor portion that includes the outermost circumferential surface and is arranged on the outer circumferential side, and an intermediate conductor portion arranged between the inner circumferential conductor portion and the outer circumferential conductor portion. Each of the conductors in the inner circumferential conductor portion has a radial width Wi and an axial height Ti. Each of the conductors in the outer peripheral conductor portion has a radial width Wo and an axial height To. Each conductor in the aforementioned intermediate conductor section has a radial width Wm and an axial height Tm. When the distance Dci in the radial direction from the central axis to the innermost peripheral surface of the inner peripheral conductor portion, the distance Dco in the radial direction from the central axis to the outermost peripheral surface of the outer peripheral conductor portion, the distance Dmi in the radial direction from the central axis to the inner diameter side end portion of the magnetic member, and the distance Dmo in the radial direction from the central axis to the outer diameter side end portion of the magnetic member are defined, at least one of Dci≤Dmi and Wi<Ti, and Dco≥Dmo and Wo<To is satisfied. Induction heating coil. (Appendix 2) The inner peripheral conductor portion and the magnetic member satisfy Dci≤Dmi and Wi<Ti. The induction heating coil according to Appendix 1. (Appendix 3) The outer peripheral conductor portion satisfies Wo<To. The induction heating coil according to Appendix 1 or Appendix 2. (Appendix 4) The outer peripheral conductor portion satisfies Dco≥Dmo. The induction heating coil according to any one of Appendices 1 to 3. (Appendix 5) When the distance Xm in the radial direction between adjacent conductors of the intermediate conductor portion, the distance Xi in the radial direction between adjacent conductors of the inner peripheral conductor portion, and the distance Xo in the radial direction between adjacent conductors of the outer peripheral conductor portion are defined for the conductor portion, Xm<Xi or Xm<Xo. The induction heating coil according to any one of Appendices 1 to 4. (Appendix 6) When the number of turns Ni of the inner peripheral conductor portion and the number of turns No of the outer peripheral conductor portion are defined for the conductor portion, Ni>No. The induction heating coil according to Appendix 5. (Appendix 7) When the number of turns Nm of the intermediate conductor portion, the number of turns Ni of the inner peripheral conductor portion, and the number of turns No of the outer peripheral conductor portion are defined for the conductor portion, Nm>Ni or Nm>No. The induction heating coil according to Appendix 5 or Appendix 6. (Appendix 8) The intermediate conductor portion satisfies Wm>Tm. An induction heating coil as described in any one of the appendices 1 through 7. (Note 9) The conductor portion is composed of a single continuous conductor and has a first transition portion that transitions from the inner circumferential conductor portion to the intermediate conductor portion, and a second transition portion that transitions from the intermediate conductor portion to the outer circumferential conductor portion. The first transition section and the second transition section are configured to be twisted 90 degrees in the radial direction. The induction heating coil described in Appendix 8. (Note 10) The conductor portion is such that Wm > Wi or Wm > Wo. An induction heating coil as described in any one of the appendices 1 through 9. (Note 11) The aforementioned conductor portion is made of aluminum and is a flat rectangular wire. An induction heating coil as described in any one of the appendices 1 through 10. (Note 12) The inner circumferential conductor portion has rounded edges on the inner diameter side of the conductor. An induction heating coil as described in any one of the notes 1 through 11. (Note 13) The outer conductor portion has rounded edges on the outer diameter side of the conductor. An induction heating coil as described in any one of the notes 1 through 12. (Note 14) The conductor portion is formed by being wound in a spiral shape around the central axis. An induction heating coil as described in any one of the appendices 1 through 13. (Note 15) Equipped with an induction heating coil as described in any one of the appendices 1 to 14, Induction heating cooker. (Note 16) It further includes a top plate on which the object to be heated is placed, The conductor portion is such that, when the axial distance between the intermediate conductor portion and the top plate is Gm, the axial distance between the inner circumferential conductor portion and the top plate is Gi, and the axial distance between the outer circumferential conductor portion and the top plate is Go, Gm = Gi or Gm = Go. The induction cooker described in Appendix 15. (Note 17) The outer peripheral conductor portion and the top plate have Gm=Gi=Go. The induction cooker described in Appendix 16. [Explanation of Symbols]

[0110] 1 Conductor section, 1a Intermediate conductor section, 1b Outer conductor section, 1c Inner conductor section, 1d First transition section, 1e Second transition section, 1i Innermost surface, 10 Outermost surface, 2 Shielding ring, 3 Magnetic member, 3a Inner diameter end, 3b Outer diameter end, 9 Top plate, 100, 100a, 100b, 110, 120, 130 Induction heating coil, 200 Induction heating cooker, CL Central axis, R Rounded edge.

Claims

1. A conductive part consisting of a conductor wound around a central axis, The magnetic member is arranged along the radial direction of the conductor portion and has an inner diameter end face which is the inner diameter end face and an outer diameter end face which is the outer diameter end face, The conductor portion comprises an inner circumferential conductor portion that includes the innermost circumferential surface and is arranged on the inner circumferential side, an outer circumferential conductor portion that includes the outermost circumferential surface and is arranged on the outer circumferential side, and an intermediate conductor portion arranged between the inner circumferential conductor portion and the outer circumferential conductor portion. Each of the conductors in the inner circumferential conductor portion has a radial width Wi and an axial height Ti. Each of the conductors in the outer peripheral conductor portion has a radial width Wo and an axial height To. Each conductor in the aforementioned intermediate conductor section has a radial width Wm and an axial height Tm. The conductor portion and the magnetic member satisfy at least one of the following conditions: Dci ≤ Dmi and Wi < Ti, and Dco ≥ Dmo and Wo < To, where Dci is the radial distance from the central axis to the innermost surface of the inner conductor portion, Dco is the radial distance from the central axis to the outermost surface of the outer conductor portion, Dmi is the radial distance from the central axis to the inner diameter side end of the magnetic member, and Dmo is the radial distance from the central axis to the outer diameter side end of the magnetic member. Induction heating coil.

2. The inner circumferential conductor portion and the magnetic member satisfy Dci ≤ Dmi and Wi < Ti. The induction heating coil according to claim 1.

3. The outer conductor portion satisfies Wo < To. The induction heating coil according to claim 2.

4. The outer conductor portion satisfies Dco ≥ Dmo. The induction heating coil according to claim 3.

5. The conductor portion is such that, when the radial distance between adjacent conductors in the intermediate conductor portion is Xm, the radial distance between adjacent conductors in the inner circumferential conductor portion is Xi, and the radial distance between adjacent conductors in the outer circumferential conductor portion is Xo, Xm < Xi or Xm < Xo. The induction heating coil according to claim 1.

6. In the aforementioned conductor portion, if Ni is the number of turns of the inner conductor portion and No is the number of turns of the outer conductor portion, then Ni > No. The induction heating coil according to claim 5.

7. The conductor portion is such that, when the number of turns of the intermediate conductor portion is Nm, the number of turns of the inner conductor portion is Ni, and the number of turns of the outer conductor portion is No, Nm > Ni or Nm > No. The induction heating coil according to claim 5.

8. The aforementioned intermediate conductor portion has Wm > Tm. The induction heating coil according to claim 1.

9. The conductor portion is composed of a single continuous conductor and has a first transition portion that transitions from the inner circumferential conductor portion to the intermediate conductor portion, and a second transition portion that transitions from the intermediate conductor portion to the outer circumferential conductor portion. The first transition section and the second transition section are configured to be twisted 90 degrees in the radial direction. The induction heating coil according to claim 8.

10. The conductor portion is such that Wm > Wi or Wm > Wo. The induction heating coil according to claim 1.

11. The aforementioned conductor portion is made of aluminum and is a flat rectangular wire. The induction heating coil according to claim 9.

12. The inner circumferential conductor portion has rounded edges on the inner diameter side of the conductor. The induction heating coil according to claim 11.

13. The outer conductor portion has rounded edges on the outer diameter side of the conductor. The induction heating coil according to claim 12.

14. The conductor portion is formed by being wound in a spiral shape around the central axis. The induction heating coil according to claim 1.

15. A device comprising an induction heating coil according to any one of claims 1 to 14, Induction heating cooker.

16. It further includes a top plate on which the object to be heated is placed, The conductor portion is such that, when the axial distance between the intermediate conductor portion and the top plate is Gm, the axial distance between the inner circumferential conductor portion and the top plate is Gi, and the axial distance between the outer circumferential conductor portion and the top plate is Go, Gm = Gi or Gm = Go. The induction heating cooker according to claim 15.

17. The outer conductor portion and the top plate have Gm = Gi = Go. The induction heating cooker according to claim 16.

Images