JP2024033322A - Induction heating coil and induction heating cooker - Google Patents

Abstract

To provide an induction heating coil and an induction heating cooker with suppressed eddy current loss.SOLUTION: An induction heating coil includes a substrate having insulating properties, and a coil portion that is provided on the substrate and consists of a conductor that is spirally wound multiple times, and the coil portion includes a first coil portion located on the innermost peripheral side, and a second coil portion connected to the first coil portion and arranged on the outer peripheral side of the first coil portion, and the winding interval of the first coil portion is larger than the winding interval of the second coil portion.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an induction heating coil that heats an object to be heated, and an induction heating cooker having the induction heating coil.

Conventionally, induction heating coils configured by pasting metal foil onto a film are known (for example, Patent Document 1).

Japanese Patent Application Publication No. 9-42696

In the induction heating coil of Patent Document 1 and the induction heating coil using a printed circuit board, unlike the induction heating coil using a litz wire made by twisting a large number of insulated thin wires, the induction heating coil is generated by magnetic flux linked to the induction heating coil. eddy current loss increases.

The present disclosure has been made to solve the above problems, and aims to provide an induction heating coil and an induction heating cooker in which eddy current loss is suppressed.

An induction heating coil according to the present disclosure includes a substrate having an insulating property, and a coil portion made of a conductor provided on the substrate and spirally wound multiple times, and the coil portion is located on the innermost side. a second coil part connected to the first coil part and arranged on the outer circumferential side of the first coil part; It is larger than the winding interval of the section.

According to the present disclosure, the first coil part disposed on the innermost side of the coil part is connected to the first coil part, and the winding pitch is smaller than that of the second coil part disposed on the outer circumference side of the first coil part. is large. Therefore, it is possible to reduce the magnetic flux interlinking with the first coil portion where magnetic flux tends to concentrate, and to reduce eddy current loss.

1 is a perspective view showing an induction heating coil according to Embodiment 1. FIG. FIG. 3 is a diagram for explaining the flow of magnetic flux in the induction heating coil according to the first embodiment. FIG. 3 is a perspective view showing an induction heating coil according to a modification of the first embodiment. FIG. 7 is a diagram for explaining the flow of magnetic flux in the induction heating coil according to a modification of the first embodiment. FIG. 3 is a perspective view of an induction heating coil according to a second embodiment. FIG. 7 is a perspective view showing an induction heating coil according to a modification of the second embodiment. FIG. 7 is a perspective view showing an induction heating coil according to Embodiment 3. FIG. 7 is a perspective view showing a third coil portion of an induction heating coil according to a third embodiment. FIG. 7 is a perspective view showing an induction heating coil according to a fourth embodiment. FIG. 7 is a perspective view showing a magnetic plate and a first auxiliary part according to a fourth embodiment. FIG. 7 is a perspective view showing an induction heating coil according to a modification of the fourth embodiment. FIG. 7 is a perspective view showing a magnetic plate, a first auxiliary part, and a second auxiliary part according to a modification of the fourth embodiment. It is a perspective view which shows the induction heating cooking device based on Embodiment 5.

Embodiments will be described below based on the drawings. In each figure, the same reference numerals are the same or equivalent, and this is common throughout the entire specification. Moreover, the forms of the constituent elements shown in the entire specification are merely examples, and the present invention is not limited to these descriptions. Furthermore, in the following drawings, the size relationship of each component may differ from the actual one.

Embodiment 1.
FIG. 1 is a perspective view showing an induction heating coil 100 according to the first embodiment. FIG. 1 is a diagram in which the X, Y, and Z axes are equiangularly arranged. The induction heating coil 100 is used, for example, in an IH cooking heater that heats an object to be heated 6 (see FIGS. 2 and 13) placed on the top plate 10 (see FIG. 13) of an induction heating cooker 200 (see FIG. 13). It is applied to an induction heating cooker 200 (see FIG. 13). The object to be heated 6 is, for example, a cooking utensil such as a metal pot. The induction heating coil 100 is installed inside the induction cooking device 200 so that the X-axis direction is vertical, and the Y-axis and Z-axis directions are horizontal. The induction heating coil 100 has a general disc shape and is made of a printed wiring board. The induction heating coil 100 includes a substrate 1, a coil portion 2, a first connector 3a, a second connector 3b, a shield ring 4, and a magnetic plate 5.

The substrate 1 is, for example, disk-shaped and made of an insulating material such as glass epoxy resin. The surface of the substrate 1 on which the object to be heated 6 is placed via the top plate 10 of the induction heating cooker 200 is referred to as the front surface, and the surface on the opposite side thereof is referred to as the back surface. The coil portion 2 is disposed on the surface of the substrate 1 and is configured by a spirally wound pattern. The pattern is made of a metal foil that is a conductor, such as copper foil, and functions as a current circuit. The widths of the patterns of the coil portion 2 are approximately the same. The coil portion 2 receives a high frequency current from an inverter circuit (not shown) connected to the first connector 3a and the second connector 3b, and generates high frequency magnetic flux. The generated magnetic flux interlinks with the bottom surface of the cooking utensil, which is the object to be heated 6 placed directly above the induction heating coil 100. When magnetic flux interlinks with the bottom surface, an eddy current is generated, and the resistance component between the eddy current and the pot generates Joule heat, which heats the bottom surface of the pot.

The coil section 2 includes a first coil section 21, a second coil section 22, and a third coil section 23. Here, in the spiral coil portion 2, an area corresponding to one rotation when the center of the substrate 1 is the center of the spiral is referred to as a turn. In other words, the coil portion 2 is composed of a plurality of consecutive turns. Note that the center of the spiral of the coil portion 2 does not have to coincide with the center of the substrate 1. The first coil portion 21 is the innermost portion of the coil portion 2 . The first coil portion 21 has a turn 211, a turn 212, and a turn 213 in this order from the inside. In the following, the winding interval of the coil part 2, that is, the distance in the radial direction of the substrate 1 between a reference turn and a turn one inner circumferentially than the reference turn, will be referred to as the winding interval of the reference turn. to be called. For example, the winding interval of the turns 212 corresponds to the distance in the radial direction of the section 21a between the turns 212 and the turns 211, with the center of the substrate 1 as the center of the coil part 2.

The second coil portion 22 is an intermediate portion of the coil portion 2 between the first coil portion 21 and the third coil portion 23 . The second coil portion 22 is connected to the first coil portion 21 and is disposed on the outer peripheral side of the first coil portion 21 . Further, the second coil portion 22 has a turn 221, a turn 222, a turn 223, and a turn 224 in this order from the inside.

The third coil portion 23 is the outermost portion of the coil portion 2 . The third coil section 23 is connected to the second coil section 22 and is disposed on the outer peripheral side of the second coil section 22. The third turn portion includes a turn 231, a turn 232, and a turn 233 in this order from the inside. The winding interval of the turns 231 corresponds to the distance in the radial direction of the section 23a between the turns 231 of the third coil part 23 and the outermost turn 224 of the second coil part 22.

The winding interval of the coil portion 2 differs depending on the portion of the coil portion 2. Specifically, in the first coil part 21 and the third coil part 23, the winding interval is larger than that in the second coil part 22. In other words, the pitch between all the turns of the first coil section 21 and the third coil section 23 is larger than the pitch between every turn of the second coil section 22 .

The first connector 3 a is provided at the outer peripheral end of the spiral coil portion 2 . The second connector 3b is provided at the inner end of the spiral coil portion 2. An inverter circuit (not shown) that supplies high frequency current to the induction heating coil 100 is connected to the first connector 3a and the second connector 3b.

The shield ring 4 is formed into an annular shape using a pattern of metal foil such as copper foil, and is arranged to surround the outer periphery of the coil portion 2 . The shield ring 4 is provided to reduce leakage magnetic flux released outside the casing 9 (see FIG. 13) of the induction heating cooker 200. Specifically, when the magnetic flux generated by the coil portion 2 interlinks with the shield ring 4, an eddy current is generated in the shield ring 4 in a direction that cancels out the generated magnetic flux, and leakage magnetic flux to the surroundings is reduced. . By forming the shield ring 4 on the same substrate 1 as the coil part 2, there is no need for a separate annular conductor made of aluminum, copper, etc., and the induction heating coil 100 can be made smaller and lower in cost. Become. Although the shield ring 4 has one turn as an example, it may be configured to have multiple turns with both ends short-circuited.

The magnetic plate 5 is made of a ferromagnetic material such as ferrite, and is installed on the back surface of the substrate 1, that is, below the coil portion 2. The magnetic plate 5 increases the density of magnetic flux generated around the coil portion 2 and increases the power input to the cooking utensil.

Next, the effects obtained by the arrangement of the coil section 2 will be explained using FIG. 2. FIG. 2 is a diagram for explaining the flow of magnetic flux in the induction heating coil 100 according to the first embodiment. FIG. 2 schematically shows a cross section of the induction heating coil 100 taken along the XZ plane. In FIG. 2, the flow of magnetic flux generated around the coil portion 2 is shown by broken lines. A magnetic flux obtained by combining the magnetic fluxes generated in each turn of the coil section 2 passes through the center of the coil section 2 and circulates so as to intersect with the coil section 2. As shown in FIG. 2, the horizontal magnetic flux passes through the bottom surface of the object to be heated 6 and the inside of the magnetic plate 5. Further, the magnetic flux in the vertical direction passes near the first coil section 21 and near the third coil section 23. Therefore, the magnetic flux interlinking around the second coil part 22 is smaller than the magnetic flux interlinking around the first coil part 21 and the third coil part 23. In other words, since the magnetic flux passes through the center of the coil section 2 and circulates so as to intersect with the coil section 2, the magnetic flux that interlinks around the first coil section 21 and the third coil section 23 is as follows. The amount of magnetic flux is large compared to the magnetic flux interlinking around the second coil portion 22.

Here, as described above, in the first coil part 21 and the third coil part 23 where magnetic flux tends to concentrate, the winding interval is larger than that in the second coil part 22. Thereby, the magnetic flux interlinking in the vicinity of the first coil section 21 and the third coil section 23 is reduced. Therefore, eddy currents generated in the first coil section 21 and the third coil section 23 can be reduced, and eddy current loss in the coil section 2 can be reduced. On the other hand, in the second coil portion 22, even if the winding interval is made small, the interlinkage magnetic flux is small as described above, so the influence on eddy current loss is small. Therefore, by reducing the winding interval of the second coil section 22, it is possible to secure the number of turns of the coil section 2 and, by extension, the necessary inductance value.

As described above, according to the first embodiment, the first coil section 21 and the third coil section 23 have a larger winding interval than the second coil section 22. Therefore, it is possible to reduce the magnetic flux interlinking with the first coil part 21 and the third coil part 23, where magnetic flux tends to concentrate, and to reduce eddy current loss. Moreover, thereby, an increase in the temperature of the coil portion 2 and a decrease in heating efficiency can be suppressed.

(Modification of Embodiment 1)
FIG. 3 is a perspective view showing an induction heating coil 110 according to a modification of the first embodiment. As shown in FIG. 3, the first coil portion 21 has a turn 211, a turn 212, a turn 213, and a turn 214 in this order from the inside. The second coil portion 22 has a turn 221, a turn 222, a turn 223, a turn 224, a turn 225, a turn 226, a turn 227, a turn 228, a turn 229, and a turn 230 in order from the inside. The third coil portion 23 has turns 231 .

The number of turns of the first coil part 21 is greater than the number of turns of the third coil part 23. The distances of the section 21a between the turns 212 and 211, the section 21b between the turns 213 and 212, and the section 21c between the turns 214 and 213 of the first coil part 21 are , which is larger than the distance between any turns of the second coil section 22. Further, the distance of the section 23a between the turn 231 of the third coil section 23 and the turn 230 of the second coil section 22 is greater than the distance between any of the turns of the second coil section 22. In other words, the number of sections having a larger winding interval than the second coil part 22 is greater in the first coil part 21 than in the third coil part 23.

FIG. 4 is a diagram for explaining the flow of magnetic flux in the induction heating coil 110 according to a modification of the first embodiment. In FIG. 4, the flow of magnetic flux generated on the upper surface of the induction heating coil 110 is shown by broken line arrows. As shown in FIG. 4, the composite magnetic flux of the magnetic fluxes generated in the coil section 2 is directed from the outer periphery of the coil section 2 toward the center of the coil. Therefore, magnetic flux concentrates from the outer periphery toward the center of the coil portion 2, and the magnetic flux density on the center side of the coil portion 2 becomes higher than on the outer periphery side. Therefore, in the first coil portion 21 located on the inner circumferential side, there is a large amount of interlinkage magnetic flux, and eddy current loss is likely to occur.

Here, in the modification of the first embodiment, the number of turns of the first coil section 21 is greater than the number of turns of the third coil section 23. Therefore, it is possible to reduce the magnetic flux interlinking with the first coil portion 21 and reduce eddy current loss. Furthermore, compared to the first embodiment, the number of turns of the second coil section 22 can be increased in place of the third coil section 23, and a necessary inductance value can be secured.

Note that the winding interval of the third coil part 23 may be made approximately equal to the winding interval of the second coil part 22, and only the winding interval of the first coil part 21 may be made larger than that of the second coil part 22. good. In this case as well, the magnetic flux interlinking with the first coil portion 21 where magnetic flux tends to concentrate can be reduced, and eddy current loss can be reduced. Moreover, thereby, an increase in the temperature of the coil portion 2 and a decrease in heating efficiency can be suppressed.

Embodiment 2.
FIG. 5 is a perspective view of the induction heating coil 120 according to the second embodiment. As shown in FIG. 5, the second embodiment differs from the first embodiment in that the width of the pattern is changed between the first coil section 21, the third coil section 23, and the second coil section 22. . In Embodiment 2, the same parts as Embodiment 1 are given the same reference numerals and explanations are omitted, and differences from Embodiment 1 will be mainly explained.

The first coil portion 21 has a turn 211, a turn 212, and a turn 213 in this order from the inside. The second coil portion 22 has a turn 221, a turn 222, a turn 223, a turn 224, and a turn 225 in this order from the inside. The third coil portion 23 has a turn 231, a turn 232, and a turn 233 in this order from the inside.

The winding interval of the induction heating coil 120 of the second embodiment is the same as the winding interval of the induction heating coil 120 of the first embodiment. That is, the first coil part 21 located on the innermost side of the coil part 2 and the third coil part 23 located on the outermost side of the coil part 2 are connected to each other. The winding interval is larger than that of the second coil portion 22 between the two coils.

The width of the pattern of the first coil part 21 and the third coil part 23 is narrower than the width of the pattern of the second coil part 22. Specifically, the width of the pattern of turns 211, turn 212, and turn 213 of the first coil portion 21 is narrower than the width of any pattern of the second coil portion 22. Further, the width of the pattern of turns 231 , turn 232 , and turn 233 of the third coil portion 23 is narrower than the width of any pattern of the second coil portion 22 .

As described in the first embodiment using FIG. 2, the magnetic flux generated by the coil section 2 passes through the center of the coil section 2 and circulates so as to intersect with the coil section 2. Therefore, the magnetic flux interlinking around the second coil part 22 is relatively small compared to the magnetic flux interlinking around the first coil part 21 and the third coil part 23. In other words, since the magnetic flux passes through the center of the coil section 2 and circulates so as to intersect with the coil section 2, the magnetic flux that interlinks around the first coil section 21 and the third coil section 23 is as follows. The amount of magnetic flux is large compared to the magnetic flux interlinking around the second coil portion 22.

According to the second embodiment, the first coil section 21 and the third coil section 23 have a larger winding interval than the second coil section 22. Furthermore, the widths of the patterns of the first coil part 21 and the third coil part 23 are narrower than the width of the patterns of the second coil part 22. Thereby, the magnetic flux interlinking in the vicinity of the first coil section 21 and the third coil section 23 can be further reduced. Therefore, the eddy currents generated in the first coil section 21 and the third coil section 23 can be reduced, and the loss of the coil section 2 can be reduced. On the other hand, in the second coil portion 22, even if the width of the pattern is increased, the interlinkage magnetic flux is small, so the influence on eddy current loss is small. Therefore, by increasing the width of the second coil section 22, it is possible to reduce the resistance component of the second coil section 22 and reduce the loss near the second coil section 22.

(Modification of Embodiment 2)
FIG. 6 is a perspective view showing an induction heating coil 130 according to a modification of the second embodiment. As shown in FIG. 6, the first coil section 21 has a turn 211, a turn 212, and a turn 213. Further, the second coil section 22 has turns 221, 222, 223, 224, 225, 226, and 227. The third coil portion 23 has turns 231. The width of the pattern of the first coil part 21 and the third coil part 23 is narrower than the width of the pattern of the second coil part 22. The number of turns of the first coil section 21 is greater than the number of turns of the third coil section 23.

As explained in the modification of the first embodiment, the composite magnetic flux of the magnetic fluxes generated in the coil section 2 is directed from the outer periphery of the coil section 2 toward the center of the coil. Therefore, magnetic flux concentrates from the outer periphery toward the center of the coil portion 2, and the magnetic flux density on the center side of the coil portion 2 becomes higher than on the outer periphery side. Therefore, in the first coil portion 21 located on the inner circumferential side, there is a large amount of interlinkage magnetic flux, and eddy current loss is likely to occur.

Here, in the modification of the second embodiment, the number of turns of the first coil section 21 is greater than the number of turns of the third coil section 23. In other words, the number of turns whose pattern width is narrower than that in the second coil part 22 is greater in the first coil part 21 than in the third coil part 23. Therefore, it is possible to reduce the magnetic flux interlinking with the first coil portion 21 and reduce eddy current loss. Furthermore, compared to the second embodiment, since the number of second coil parts 22 can be increased in place of the third coil part 23, the number of cycles with thick patterns can be increased. Therefore, in the modification of the second embodiment, the resistance component of the coil portion 2 can be further reduced compared to the second embodiment. Therefore, eddy current loss in the coil portion 2 can be reduced.

Embodiment 3.
FIG. 7 is a perspective view showing an induction heating coil 140 according to the third embodiment. FIG. 7 shows a cross section of the induction heating coil 140 taken along a plane parallel to the X-axis. As shown in FIG. 7, the third embodiment differs from the second embodiment in that the coil portions 2 are provided on both sides of the substrate 1. In Embodiment 3, the same parts as Embodiment 2 are given the same reference numerals, explanations are omitted, and differences from Embodiment 2 will be mainly explained.

The induction heating coil 140 has a coil portion 2A and a coil portion 2B. The coil portion 2A and the coil portion 2B are connected in parallel between, for example, the first connector 3a and the second connector 3b.

The coil section 2A includes a first coil section 21A, a second coil section 22A, and a third coil section 23A. The first coil section 21A and the second coil section 22A are arranged on the surface of the substrate 1. The first coil portion 21A is the innermost portion of the coil portion 2A. The second coil portion 22A is an intermediate portion of the coil portion 2A between the first coil portion 21A and the third coil portion 23A. The second coil portion 22A is connected to the first coil portion 21A and is disposed on the outer peripheral side of the first coil portion 21A. The width of the pattern of the first coil portion 21A is narrower than the width of the pattern of the second coil portion 22A. A description of the third coil portion 23A will be given later.

The coil portion 2B includes a first coil portion 21B, a second coil portion 22B, and a third coil portion 23B. The first coil section 21B and the second coil section 22B are arranged on the back surface of the substrate 1. The first coil portion 21B is the innermost portion of the coil portion 2B. The second coil portion 22B is an intermediate portion of the coil portion 2B between the first coil portion 21B and the third coil portion 23B. The second coil portion 22B is connected to the first coil portion 21B and is disposed on the outer peripheral side of the first coil portion 21B. The width of the pattern of the first coil portion 21B is narrower than the width of the pattern of the second coil portion 22B. The first coil section 21B and second coil section 22B arranged on the back surface are arranged so as to substantially overlap in the vertical direction with the first coil section 21A and second coil section 22A on the front surface.

The third coil portion 23A is the outermost portion of the coil portion 2A. The third coil portion 23A is connected to the second coil portion 22A and is disposed on the outer peripheral side of the second coil portion A. The third coil portion 23B is the outermost portion of the coil portion 2B. The third coil portion 23B is connected to the second coil portion 22B and is disposed on the outer peripheral side of the second coil portion B. FIG. 8 is a perspective view showing the third coil portion 23A and the third coil portion 23B of the induction heating coil 140 according to the third embodiment. In FIG. 8, illustration of the substrate 1 and the like is omitted, and only the third coil portion 23A and the third coil portion 23B are shown. Further, in FIG. 8, only the third coil portion 23B is shown hatched for convenience. As shown in FIGS. 7 and 8, the surfaces of the third coil portion 23A and the third coil portion 23B on the substrate 1 are alternately arranged at regular intervals in the circumferential direction. In the third coil portion 23A and the third coil portion 23B, the front surface pattern and the back surface pattern are connected via a through hole (not shown) plated with copper foil, for example.

Generally, when the coil section 2A and the coil section 2B are arranged on both the front and back surfaces of the substrate 1, the coil section 2B on the back surface of the substrate 1 has a smaller eddy current loss than the coil section 2A on the front surface. This is because the coil portion 2A on the front surface of the substrate 1 serves as a magnetic shield for the coil portion 2B on the back surface. Therefore, the coil portion 2A on the front surface of the substrate 1 has a larger eddy current loss than the coil portion 2B on the back surface, and temperature rise becomes a problem.

According to the third embodiment, the surfaces on which the third coil portion 23A and the third coil portion 23B are arranged on the substrate 1 are alternately replaced. Therefore, the eddy current losses of the third coil portion 23A and the third coil portion 23B are approximately the same. Therefore, the temperature increases in the third coil portion 23A and the third coil portion 23B can be balanced, and the temperature of the front coil portion 2A can be prevented from rising excessively than the temperature of the back coil portion 2B. . Therefore, when the induction heating coil 140 is applied to the induction heating cooker 200, cooling of the induction heating coil 140 is facilitated, such as by simplifying the cooling device, etc., and the entire induction heating cooker 200 is This makes it possible to make the product thinner.

In the third embodiment, the surfaces on which the outermost third coil portion 23A and third coil portion 3B, which are likely to cause eddy current loss, are arranged are switched between the front surface and the back surface at regular intervals. It was configured as follows. However, the surfaces on which the first coil portion 21A and the first coil portion 21B on the inner circumferential side are arranged may also be configured to be alternated between the front surface and the back surface of the substrate 1 at regular intervals. Further, the surface arranged on the substrate 1 may be changed over a plurality of turns into a front surface and a back surface at regular intervals.

Embodiment 4.
FIG. 9 is a perspective view showing an induction heating coil 150 according to the fourth embodiment. As shown in FIG. 9, the fourth embodiment differs from the first embodiment in that it includes a first auxiliary section 7. As shown in FIG. In Embodiment 4, the same parts as in Embodiment 1 are given the same reference numerals and explanations are omitted, and differences from Embodiment 1 will be mainly explained.

A magnetic plate 5 is arranged on the back surface of the substrate 1. A first through hole 70 penetrating from the front surface to the back surface is formed in the center of the coil portion 2 of the substrate 1 . The first auxiliary part 7 is a part made of a ferromagnetic material such as ferrite, and has a cylindrical shape, for example. The first auxiliary part 7 is placed in contact with the magnetic plate 5 at the center of the coil part 2, passes through the first through hole 70, and is arranged so as to protrude beyond the surface of the substrate 1. The first auxiliary portion 7 has a function of assisting the formation of a magnetic path with low magnetic resistance.

The effects of the magnetic plate 5 and the first auxiliary part 7 will be explained using FIG. 10. FIG. 10 is a perspective view showing the magnetic plate 5 and the first auxiliary part 7 according to the fourth embodiment. In FIG. 10, the flow of magnetic flux generated inside the magnetic plate 5 and the first auxiliary part 7 is shown by broken lines. As shown in FIG. 10, the magnetic flux generated inside the magnetic plate 5 gathers at the center of the magnetic plate 5, passes through the first auxiliary part 7 in the vertical direction, and is transferred to the heated object 6 (see FIG. 2). Head to the bottom. In this way, the magnetic flux generated by the coil section 2 flows through the magnetic plate 5, the first auxiliary section 7, and the object to be heated 6 in this order.

Generally, the amount of magnetic flux generated by the coil portion 2 is affected by the magnetic permeability of the path through which the magnetic flux passes. The relative magnetic permeability of ferrite material is about 2000, and it is known that magnetic flux passes through it more easily than air. According to the fourth embodiment, the first auxiliary part 7 is provided in the induction heating coil 150. Therefore, a path of magnetic flux toward the bottom surface of the object to be heated 6 is formed, and the magnetic flux can be efficiently linked to the object to be heated 6. Further, in a path that passes through the center of the coil section 2 and goes around so as to intersect with the coil section 2, the magnetic resistance decreases and the generated magnetic flux increases. That is, according to the first auxiliary part 7, the object to be heated 6 can be efficiently heated with a small amount of current. In particular, by arranging the magnetic plate 5 and the first auxiliary part 7 in contact with each other, an air layer can be eliminated and an increase in magnetic resistance can be suppressed. Note that the magnetic plate 5 and the first auxiliary part 7 may be integrally molded.

(Modification of Embodiment 4)
FIG. 11 is a perspective view showing an induction heating coil 160 according to a modification of the fourth embodiment. As shown in FIG. 11, the modification of the fourth embodiment further includes a second auxiliary part 8a, a second auxiliary part 8b, a second auxiliary part 8c, and a second auxiliary part 8d.

The substrate 1 has a second through hole 80a, a second through hole 80b, a second through hole 80c, and a second through hole 80d that penetrate from the front surface to the back surface between the third coil part 23 and the shield ring 4. It is formed. The outer periphery of the coil portion 2 is surrounded by the second through hole 80a, the second through hole 80b, the second through hole 80c, and the second through hole 80d. The second auxiliary part 8a, the second auxiliary part 8b, the second auxiliary part 8c, and the second auxiliary part 8d are all parts made of a ferromagnetic material such as ferrite, and have, for example, an arcuate column shape. The second auxiliary part 8a, the second auxiliary part 8b, the second auxiliary part 8c, and the second auxiliary part 8d are in contact with the magnetic plate 5 at the outer periphery of the coil part 2, respectively, and It passes through the second through hole 80b, the second through hole 80c, and the second through hole 80d, and is arranged so as to protrude from the surface of the substrate 1. The second auxiliary portion 8a, the second auxiliary portion 8b, the second auxiliary portion 8c, and the second auxiliary portion 8d have a function of assisting the formation of a magnetic path with low magnetic resistance. Note that the second auxiliary part 8a, the second auxiliary part 8b, the second auxiliary part 8c, and the second auxiliary part 8d may be collectively referred to as the second auxiliary part 8.

The effects of the magnetic plate 5, the first auxiliary part 7, and the second auxiliary part 8 will be explained using FIG. 12. FIG. 12 is a perspective view showing the magnetic plate 5, the first auxiliary part 7, the second auxiliary part 8a, the second auxiliary part 8b, the second auxiliary part 8c, and the second auxiliary part 8d according to a modification of the fourth embodiment. It is a diagram. In FIG. 12, the flow of magnetic flux generated inside the magnetic plate 5, the first auxiliary part 7, and the second auxiliary part 8 is shown by broken lines. As shown in FIG. 12, the magnetic flux generated inside the magnetic plate 5 gathers at the center of the magnetic plate 5, passes through the first auxiliary part 7 in the vertical direction, and heads toward the heating surface of the object to be heated 6. Further, the magnetic flux that has passed through the object to be heated 6 passes through each of the second auxiliary part 8a, the second auxiliary part 8b, the second auxiliary part 8c, and the second auxiliary part 8d, and returns to the magnetic plate 5. In this way, the magnetic flux generated by the coil section 2 is transmitted to the magnetic plate 5, the first auxiliary section 7, the object to be heated 6, the second auxiliary section 8a, the second auxiliary section 8b, the second auxiliary section 8c, and the second auxiliary section. 8d, and the magnetic plate 5 in this order.

As described above, by providing the second auxiliary part 8a, the second auxiliary part 8b, the second auxiliary part 8c, and the second auxiliary part 8d, a magnetic path with low magnetic resistance is formed, the amount of magnetic flux increases, and the The magnetic flux can be linked to the object 6 to be heated. Therefore, according to the modification of the fourth embodiment, it is possible to improve the heating efficiency.

Note that if the second auxiliary part 8 is provided around one circumference of the induction heating coil 160, that is, over the entire 360 degrees, the coil part 2 and the substrate 1 of the shield ring 4 will be separated, so in the modification of the fourth embodiment, A second auxiliary part 8a, a second auxiliary part 8b, a second auxiliary part 8c, and a second auxiliary part 8d are provided to prevent the substrate 1 from being divided. That is, by providing a plurality of second auxiliary parts 8, the coil part 2 and the shield ring 4 can be constructed from the same substrate 1.

Moreover, the magnetic plate 5, the first auxiliary part 7, and the second auxiliary part 8 may be integrally molded. Further, in the modification of the fourth embodiment, a case is shown in which both the first auxiliary part 7 and the second auxiliary part 8 are provided, but the same effect can be obtained even with only the second auxiliary part 8.

Embodiment 5.
FIG. 13 is a perspective view showing an induction heating cooker 200 according to the fifth embodiment. In FIG. 13, the induction heating cooker 200 is shown with the top plate 10 removed. As shown in FIG. 13, the induction heating cooker 200 includes a housing 9, a top plate 10, an induction heating coil 170a, an induction heating coil 170b, an inverter board 12, an operation section 13, and a display section 14. Note that the induction heating coil 170a and the induction heating coil 170b may be referred to as the induction heating coil 170 without distinction.

The housing 9 accommodates the induction heating coil 170a, the induction heating coil 170b, the inverter board 12, the operation section 13, the display section 14, a cable (not shown), a connector (not shown), and the like. The top plate 10 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. Although FIG. 13 shows an example in which two circular heating ports are provided, that is, an example in which two induction heating coils 170 are applied, the number of heating ports is not limited to the illustrated example.

Inverter board 12 includes a rectifier circuit that converts alternating current power into direct current, generates high frequency current from direct current, and supplies it to induction heating coil 170 . The inverter board 12 is configured with a known circuit such as a half-bridge inverter, a full-bridge inverter, or a single-stone voltage resonance inverter. The operation unit 13 is for the user to adjust the firepower, etc., and is, for example, a touch panel type. The arrangement and structure of the operating section 13 are not limited to the illustrated example, and may also be of a dial type or tact switch type. The display unit 14 notifies the user of the heating power, elapsed heating time, etc., and is, for example, a liquid crystal display. The arrangement and structure of the display section 14 is not limited to the illustrated example, and may also be a 7-segment LED (Light Emitting Diode).

Induction heating coil 170a and induction heating coil 170b correspond to the induction heating coil described in any of the first to fourth embodiments. The induction heating coils 170a and 170b are connected to the inverter board 12, are supplied with a high frequency current from the inverter board 12, and heat the object 6 placed on the top plate 10 by induction.

According to the fifth embodiment, the magnetic flux interlinking with the first coil portion 21 where magnetic flux tends to concentrate can be reduced, and eddy current loss can be reduced.

Although the embodiments have been described above, the present disclosure is not limited to the embodiments described above, and various modifications or combinations can be made without departing from the gist of the present disclosure. For example, in the first embodiment and the modification of the first embodiment, as shown in FIGS. 1 and 3, the coil portion 2 is arranged on the surface side of the substrate 1 on which the object to be heated 6 is placed. explained. However, the surface on which the coil portion 2 is arranged is not limited to this. For example, the coil portion 2 may be arranged on the back surface of the substrate 1, or may be provided on both surfaces as in the third embodiment. When the coil portions 2 are provided on both sides, the coil portions 2 on the front surface and the coil portions 2 on the back surface may be connected in series, or may be connected in parallel between the first connector 3a and the second connector 3b. When connected in series, the inductance can be increased. On the other hand, when connected in parallel, the total cross-sectional area of the coil section 2 is doubled, so the resistance component of the coil section 2 can be reduced. Furthermore, a structure in which a plurality of coil parts 2 are stacked using a multilayer printed wiring board may be used. Note that it is desirable that the plurality of stacked coil parts 2 are arranged so as to substantially overlap when viewed from the top surface side of the substrate 1. Thereby, the magnetic flux interlinking with the coil portion 2 can be reduced.

Further, in each of the embodiments and their modifications, the winding intervals in each of the first coil section 21, second coil section 22, and third coil section 23 are made substantially constant. However, the winding interval of the coil portion 2 is not limited to this. For example, in the first coil part 21, the winding interval gradually increases as it approaches the center of the coil part 2, and in the third coil part 23, the winding interval gradually increases as it approaches the outer circumference of the coil part 2. You may do so. In this case, the magnetic flux linkage to the coil section 2 can be reduced in response to the magnetic flux density increasing toward the center of the coil section 2 and the magnetic flux density increasing toward the outer circumference of the coil section 2, and the eddy current loss can be suppressed.

In each of the embodiments and their modifications, the coil part 2 is composed of a single piece of metal foil, and the first coil part 21, the second coil part 22 and Although the configuration is shown in the case where it is divided into the third coil section 23, the configuration of the coil section 2 is not limited to this case. Each of the first coil part 21, second coil part 22, and third coil part 23 is made of metal foil, and the first coil part 21 and the second coil part 22 have a connection part (not shown) of metal foil. The second coil portion 22 and the third coil portion 23 may be connected via a metal foil connection portion (not shown).

Below, various aspects of the present disclosure will be added.

(Additional note 1)
a substrate having insulating properties;
a coil portion provided on the substrate and made of a conductor wound spirally a plurality of times;
The coil portion is
a first coil portion disposed on the innermost side;
a second coil part connected to the first coil part and arranged on the outer peripheral side of the first coil part,
The winding interval of the first coil part is larger than the winding interval of the second coil part. The induction heating coil.
(Additional note 2)
The coil portion is
further comprising a third coil part connected to the second coil part and arranged on the outer peripheral side of the second coil part,
The induction heating coil according to supplementary note 1, wherein a winding interval of the third coil part is larger than a winding interval of the second coil part.
(Additional note 3)
The induction heating coil according to supplementary note 2, wherein the number of turns of the first coil portion is greater than the number of turns of the third coil portion.
(Additional note 4)
The induction heating coil according to appendix 2 or 3, wherein the first coil part and the third coil part have a width smaller than the second coil part.
(Appendix 5)
The induction heating coil according to any one of Supplementary Notes 1 to 4, further comprising an annular shield ring made of metal foil disposed on the outer peripheral side of the coil portion of the substrate.
(Appendix 6)
a magnetic plate disposed on the back surface of the substrate opposite to the surface on which the heated object is placed;
a first auxiliary part made of a ferromagnetic material and protruding from the surface at the center of the coil part of the substrate;
The substrate has a first through hole formed in the center of the coil part,
The induction heating coil according to any one of Supplementary Notes 1 to 5, wherein the first auxiliary part contacts the magnetic plate through the first through hole.
(Appendix 7)
a magnetic plate disposed on the back surface of the substrate opposite to the surface on which the heated object is placed;
a second auxiliary part made of a ferromagnetic material and protruding from the surface on the outer periphery of the coil part of the substrate;
The substrate has a second through hole formed on the outer periphery of the coil part,
The induction heating coil according to any one of Supplementary Notes 1 to 6, wherein the second auxiliary part contacts the magnetic plate through the second through hole.
(Appendix 8)
comprising two of the coil parts arranged on both sides of the substrate,
The first coil part or the third coil part each of the two coil parts has,
The induction heating coil according to any one of Supplementary Notes 2 to 7, wherein the surfaces arranged on the substrate are alternated.
(Appendix 9)
An induction heating cooker comprising the induction heating coil according to any one of Supplementary Notes 1 to 8.

1 Substrate, 2, 2A, 2B Coil part, 3a First connector, 3b Second connector, 4 Shield ring, 5 Magnetic plate, 6 Heated object, 7 First auxiliary part, 8, 8a, 8b, 8c, 8d 2 auxiliary part, 9 housing, 10 top plate, 12 inverter board, 13 operation part, 14 display part, 21, 21A, 21B first coil part, 21a, 21b, 21c section, 22, 22A, 22B second coil part , 23, 23A, 23B Third coil part, 23a section, 70 First through hole, 80a, 80b, 80c, 80d Second through hole, 100, 110, 120, 130, 140, 150, 160, 170, 170a, 170b induction heating coil, 200 induction heating cooker, 211-214, 221-233 turns.

Claims (9)

a substrate having insulating properties;
a coil portion provided on the substrate and made of a conductor wound spirally a plurality of times;
The coil portion is
a first coil portion disposed on the innermost side;
a second coil part connected to the first coil part and arranged on the outer peripheral side of the first coil part,
The winding interval of the first coil part is larger than the winding interval of the second coil part. The induction heating coil. The coil portion is
further comprising a third coil part connected to the second coil part and arranged on the outer peripheral side of the second coil part,
The induction heating coil according to claim 1, wherein a winding interval of the third coil part is larger than a winding interval of the second coil part. The induction heating coil according to claim 2, wherein the number of turns of the first coil section is greater than the number of turns of the third coil section. The induction heating coil according to claim 2 or 3, wherein the widths of the first coil part and the third coil part are narrower than the width of the second coil part. The induction heating coil according to any one of claims 1 to 3, further comprising an annular shield ring made of metal foil arranged on the outer peripheral side of the coil portion of the substrate. a magnetic plate disposed on the back surface of the substrate opposite to the surface on which the heated object is placed;
a first auxiliary part made of a ferromagnetic material and protruding from the surface at the center of the coil part of the substrate;
The substrate has a first through hole formed in the center of the coil part,
The induction heating coil according to any one of claims 1 to 3, wherein the first auxiliary part contacts the magnetic plate through the first through hole. a magnetic plate disposed on the back surface of the substrate opposite to the surface on which the heated object is placed;
a second auxiliary part made of a ferromagnetic material and protruding from the surface on the outer periphery of the coil part of the substrate;
The substrate has a second through hole formed on the outer periphery of the coil part,
The induction heating coil according to any one of claims 1 to 3, wherein the second auxiliary part contacts the magnetic plate through the second through hole. comprising two of the coil parts arranged on both sides of the substrate,
The first coil part or the third coil part each of the two coil parts has,
The induction heating coil according to claim 2 or 3, wherein the surfaces arranged on the substrate are alternated. An induction heating cooker comprising the induction heating coil according to any one of claims 1 to 3.

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