Induction heating cooker

Abstract

To obtain an induction heating cooker capable of supplying more power.SOLUTION: An induction heating cooker includes: a substrate having a front surface facing an object to be heated and a back surface opposite to the front surface; an induction heating coil having a back surface coil part in which a conductor is wound a plurality of times to form a spiral conductor pattern on the back surface of the substrate, the induction heating coil heating the object to be heated; and cooling means for cooling the induction heating coil on the back surface side of the substrate.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present technology relates to an induction heating cooker including an induction heating coil for heating an object to be heated. In particular, it relates to improving heating efficiency.

Background Art

[0002] Conventionally, an induction heating cooker provided below a top plate on which an object to be heated such as a pan is placed and having an induction heating coil for heating the object to be heated is known. In such an induction heating cooker, there is an induction heating coil configured by attaching a metal foil to a film (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the induction heating coil using the induction heating coil and printed circuit board of Patent Document 1, resin is used as a material for the film, base material, etc. Since the resin has a low heat-resistant temperature, the magnitude of the power supplied to the induction heating coil has been limited.

[0005] An object of the present disclosure is to obtain an induction heating cooker capable of supplying a larger amount of power in order to solve the above-described problems.

Means for Solving the Problems

[0006] The induction heating cooker according to the present disclosure includes a substrate having a front surface that is a surface facing the object to be heated and a back surface that is the surface opposite to the front surface, and a back surface coil portion formed by winding a conductor a plurality of times on the back surface of the substrate to form a spiral conductor pattern, an induction heating coil for heating the object to be heated, and a cooling means for cooling the induction heating coil on the back surface side of the substrate.

Advantages of the Invention

[0007] In the induction heating cooker according to the present disclosure, in the induction heating coil, the back surface coil portion is provided on the back surface of the substrate, and the cooling means cools the induction heating coil from the back surface side of the substrate. Therefore, since the front surface side is not cooled, the distance between the induction heating coil and the object to be heated can be reduced, and the linked magnetic flux to the object to be heated can be increased. Accordingly, a large amount of electric power can be supplied by the coil portion of the induction heating coil, and the heating efficiency can be improved.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the induction heating cooker according to the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments, and various modifications can be made without departing from the gist of the present disclosure. Further, the present disclosure includes all combinations of configurations that can be combined among the configurations shown in the following embodiments. In addition, the induction heating coil shown in the drawings is an example of a coil to which the technical idea of the present disclosure is applied, and the induction heating coil and the like applied to the present disclosure are not limited by the aspects shown in the drawings. The induction heating cooker shown in the drawings is an example of a device to which the technical idea of the present disclosure is applied. In the following description, terms indicating directions (for example, "right", "left", "front", "rear", etc.) are appropriately used for easy understanding, but these are for the purpose of explanation and do not limit the present disclosure. Also, in each figure, those with the same reference numerals are the same or corresponding ones, which is common throughout the specification. Note that in each drawing, the relative dimensional relationships or shapes of the respective components may be different from the actual ones.

[0010] Embodiment 1. FIG. 1 is a perspective view showing the appearance of an example of an induction heating cooker according to Embodiment 1. FIG. 1 shows the induction heating cooker 200 with the top plate 52 removed from the induction heating cooker 200 in order to make the inside of the induction heating cooker 200 visible. The induction heating cooker 200 is a cooking heater such as an IH (Induction Heating) cooking heater that heats the object to be heated 51 placed on the top plate 52. The object to be heated 51 is, for example, a cooking utensil such as a metal pot.

[0011] As shown in FIG. 1, the induction heating cooker 200 includes a housing 53, a top plate 52, induction heating coils 100a and 100b, an inverter board 61, an operation unit 62, and a display unit 63. Here, when the induction heating coils 100a and 100b are not distinguished, they are referred to as the induction heating coil 100.

[0012] The housing 53 houses the induction heating coils 100a and 100b, the inverter board 61, the operation unit 62, the display unit 63, a cable (not shown), a connector (not shown), and a cooling fan 54 (see FIG. 3) described later. The top plate 52 is a plate on which the object to be heated 51 is placed and is made of a non-metallic material such as heat-resistant glass or ceramic. FIG. 1 shows an example in which two circular heating openings are provided in the top plate 52, and the induction heating coil 100a is applied to one of the two heating openings and the induction heating coil 100b is applied to the other heating opening, but the number of heating openings is not limited to the example shown in FIG. 1.

[0013] The inverter board 61 has a rectifier circuit (not shown) that converts an AC power supply into DC and an inverter circuit (not shown) that generates a high-frequency current from the DC and supplies it to the induction heating coil 100. The inverter circuit (not shown) is composed of a known electric circuit such as, for example, a half-bridge inverter, a full-bridge inverter, or a single-stone voltage resonance inverter. The operation unit 62 is for the user to perform operations such as adjusting the heating power, and is, for example, a touch panel type input device. The arrangement and structure of the operation unit 62 are not limited to the example shown in FIG. 1. For example, the operation unit 62 may be of a dial type or a tact switch type. The display unit 63 notifies the user of the heating power, the elapsed heating time, etc., and has, for example, a liquid crystal display. The arrangement and structure of the display unit 63 are not limited to the example shown in FIG. 1. For example, it may have a 7-segment LED (Light Emitting Diode) and perform display.

[0014] FIG. 2 is a plan view showing an example of the induction heating coil according to Embodiment 1. The induction heating coil 100 is connected to the inverter board 61, supplied with a high-frequency current from the inverter board 61, and inductively heats the object to be heated 51 placed on the top plate 52. The induction heating coil 100 in Embodiment 1 has a printed circuit board. The printed circuit board is a board on which an electric circuit or a pattern of wiring (conductor pattern) is formed by a printing technique using a conductor such as, for example, copper foil. Therefore, the induction heating coil 100 in Embodiment 1 has a substrate 1, a coil portion 2, a first connector 3a, a second connector 3b, a shield ring 4, and a magnetic body 5.

[0015] The substrate 1 is, for example, disk-shaped and is a flat plate made of a material having insulation properties such as glass epoxy resin. Here, of the two planes of the substrate 1, the surface facing the object to be heated 51 through the top plate 52 shown in FIG. 1 is referred to as the front surface, and the opposite surface is referred to as the back surface. FIG. 2 shows the configuration of the induction heating coil 100 when looking at the back surface of the substrate 1. The coil part 2 is arranged at least on the back surface of the substrate 1. Here, the coil part 2 is arranged not only on the back surface of the substrate 1 but also on both surfaces. And in the coil part 2, the one arranged on the front surface of the substrate 1 is referred to as the front surface coil part 2a (see FIG. 3 described later), and the one arranged on the back surface is referred to as the back surface coil part 2b. The coil part 2 is configured in a pattern in which a conductor is wound a plurality of times in a spiral shape on the substrate 1. The coil part 2 is made of a metal foil which is a conductor such as copper foil, and functions as an electric circuit through which an electric current flows. Here, although the coil part 2 in FIG. 2 has a constant width of the conductor and a spiral pattern is formed, it is not limited thereto.

[0016] As shown in FIG. 2, when the coil portion 2 is viewed in the radial direction from the center of winding, there is no metal foil between the conductors of one turn and the conductors of the adjacent turn. Therefore, the coil portion 2 is wound while maintaining a predetermined interval between the conductors adjacent in the radial direction. For this reason, it is possible to reduce the influence of the magnetic flux by the conductors adjacent in the radial direction and reduce the energy loss in the coil portion 2. Further, the front surface coil portion 2a and the back surface coil portion 2b are arranged at the same position such that the conductor pattern (not shown) in the front surface coil portion 2a and the conductor pattern in the back surface coil portion 2b overlap when the substrate 1 is viewed from above. The inner peripheral side end portion (center of winding) of the conductor (not shown) in the front surface coil portion 2a and the inner peripheral side end portion of the conductor in the back surface coil portion 2b are electrically connected via, for example, a through hole (not shown) formed in the substrate 1, and further electrically connected to the first connector 3a. Also, the outer peripheral side end portion of the conductor (not shown) in the front surface coil portion 2a and the outer peripheral side end portion of the conductor in the back surface coil portion 2b are also electrically connected via, for example, a through hole (not shown), and further electrically connected to the second connector 3b. Therefore, the front surface coil portion 2a and the back surface coil portion 2b are electrically connected in parallel. The first connector 3a and the second connector 3b will be described later. Here, the through hole is a through hole provided in the substrate 1. By applying, for example, copper foil plating to the wall surface of the through hole, the conductor pattern of the front surface coil portion 2a and the conductor pattern of the back surface coil portion 2b can be electrically connected.

[0017] Here, in the coil part 2, among the conductors forming the conductor pattern, the conductor for one winding (one turn) formed on the inner peripheral side when viewed in the radial direction from the center of the winding is particularly referred to as the inner peripheral side conductor. In FIGS. 2 and 3 described later, in the surface coil part 2a, the conductors for four turns on the inner peripheral side are referred to as the inner peripheral side conductor 2a1, the inner peripheral side conductor 2a2, the inner peripheral side conductor 2a3, and the inner peripheral side conductor 2a4. Further, in the back surface coil part 2b, the conductors for four turns on the inner peripheral side are referred to as the inner peripheral side conductor 2b1, the inner peripheral side conductor 2b2, the inner peripheral side conductor 2b3, and the inner peripheral side conductor 2b4. The inner peripheral side conductor 2a1 and the inner peripheral side conductor 2b1 are electrically connected to each other by the through hole 6. Similarly, the inner peripheral side conductor 2a2 and the inner peripheral side conductor 2b2, the inner peripheral side conductor 2a3 and the inner peripheral side conductor 2b3, and the inner peripheral side conductor 2a4 and the inner peripheral side conductor 2b4 are also electrically connected to each other by the through hole 6. The through hole 6 is a through hole provided with copper foil plating or the like for electrically connecting the conductor pattern of the surface coil part 2a and the conductor pattern of the back surface coil part 2b on the wall surface.

[0018] The connector 3 is a terminal that electrically connects between an inverter circuit (not shown) and the coil part 2 and supplies a high-frequency current from the inverter circuit (not shown) to the coil part 2. The connector 3 has the first connector 3a and the second connector 3b described above. The first connector 3a is electrically connected to the conductor end portion at the innermost circumference in the spiral coil part 2. Further, the second connector 3b is electrically connected to the conductor end portion at the outermost circumference in the coil part 2. The coil part 2 receives the supply of a high-frequency current from the inverter circuit (not shown) via the first connector 3a and the second connector 3b and generates a high-frequency magnetic flux. The generated magnetic flux links to the bottom surface of the object to be heated 51 (see FIG. 1) placed directly above the induction heating coil 100. When the magnetic flux links to the bottom surface of the object to be heated 51, eddy currents are generated on the bottom surface of the object to be heated 51, and Joule heat is generated by the resistance component between the eddy currents and the object to be heated 51, and the bottom portion of the object to be heated 51 is heated.

[0019] Here, in the induction heating coil 100, the surface on which the first connector 3a and the second connector 3b are installed may be either the front or back surface of the substrate 1, but it is more desirable to provide them on the back surface. By providing the connector 3 on the back surface of the substrate 1, for example, when an inverter circuit (not shown) is arranged below the substrate 1, the inverter circuit (not shown) and the coil portion 2 can be connected at a short distance. Also, providing the first connector 3a and the second connector 3b on the back surface can reduce the distance between the coil portion 2 and the top plate 52. Therefore, the distance between the object to be heated 51 and the coil portion 2 can be reduced, and the heating efficiency can be improved.

[0020] The shield ring 4 is formed in a ring shape, for example, in a pattern of a metal foil such as a copper foil, and is arranged to surround the outer periphery of the coil portion 2. The shield ring 4 is provided to reduce the leakage magnetic flux emitted outside the housing 53 (see FIG. 1) of the induction heating cooker 200. Specifically, when the magnetic flux generated by the coil portion 2 intersects with the shield ring 4, eddy currents are generated in the shield ring 4 in a direction to cancel the intersecting magnetic flux, and the leakage magnetic flux to the surroundings is reduced. By forming the shield ring 4 on the same substrate 1 as the coil portion 2, and performing printing or the like in the same process as the coil portion 2, there is no need to separately provide an annular conductor made of aluminum or copper or the like. Therefore, the induction heating coil 100 can be miniaturized and cost-reduced. Here, FIG. 2 shows an example of the shield ring 4 where the conductor is wound once, but a configuration where a single conductor is wound multiple times and both ends of the conductor are short-circuited may also be used. Also, the shield ring 4 may be arranged on either the front or back surface of the substrate 1, or on both surfaces of the substrate 1.

[0021] The magnetic body 5 is made of a ferromagnetic material such as ferrite, for example. The magnetic body 5 is installed below the back surface coil portion 2b on the back surface side of the substrate 1. The magnetic body 5 increases the density of the magnetic flux generated around the coil portion 2 and increases the input power to the object to be heated 51. The magnetic body 5 has a rod shape and is arranged along the radial direction from the center of the coil portion 2 so that the longitudinal direction of the rod is parallel to the radial direction. FIG. 2 shows a case where a plurality of magnetic bodies 5 are arranged radially from the center of the coil portion 2 to the outer peripheral side. Further, at least the conductor of the coil portion 2 of the induction heating coil 100 is provided with a solder resist (not shown) for insulating and protecting the conductor.

[0022] Here, with reference to FIG. 2, the positional relationship among the back surface coil portion 2b, the shield ring 4, and the magnetic body 5 of the substrate 1 has been described. However, on the front surface of the substrate 1 as well, these positional relationships are the same. Also in the following, among the front surface and the back surface of the substrate 1, the configuration described for one surface may be the same for the other surface.

[0023] FIG. 3 is a diagram showing the positional relationship of the induction heating coil in the housing of the induction heating cooker according to Embodiment 1. The induction heating cooker 200 includes an induction heating coil 100 and a cooling fan 54 inside the housing 53. FIG. 3 particularly shows the positional relationship between the induction heating coil 100 and the cooling fan 54. The cooling fan 54 serving as a cooling means is, for example, an axial flow fan. The cooling fan 54 is arranged in the housing 53 below the induction heating coil 100 so that the wind direction blows upward toward the back surface coil portion 2b of the induction heating coil 100. The cooling fan 54 is configured such that a large amount of cooling air hits particularly near the inner peripheral side conductors 2b1, 2b2, 2b3, and 2b4 of the back surface coil portion 2b.

[0024] FIG. 4 is a diagram for explaining the flow of magnetic flux in the magnetic material of the induction heating coil according to Embodiment 1. In FIG. 4, the flow of magnetic flux generated in the induction heating coil 100 is indicated by a broken-line arrow. Here, the reason for mainly cooling the conductor on the inner peripheral side of the coil portion 2 in the induction heating coil 100 will be explained. As shown in FIG. 4, the combined magnetic flux of the magnetic flux generated in the coil portion 2 is directed from the outer peripheral side of the coil portion 2 toward the center of the coil portion 2. For this reason, the magnetic flux density near the center of the coil portion 2 is higher than that on the outer peripheral side. In a region where the magnetic flux density is high, since the magnetic flux penetrating the conductor constituting the coil portion 2 also increases, the eddy current becomes large. When the eddy current is generated, Joule loss, that is, eddy current loss, occurs in the conductor, and the temperature of the conductor of the coil portion 2 rises.

[0025] Therefore, in the induction heating cooker 200 according to Embodiment 1, the inner peripheral side conductors 2a1 to 2a4 and the inner peripheral side conductors 2b1 to 2b4 on the spiral inner peripheral side of the coil portion 2 are connected via a plurality of through holes 6. For this reason, the heat generated in the inner peripheral side conductors 2a1 to 2a4 in the surface coil portion 2 is transmitted to the inner peripheral side conductors 2b1 to 2b4 of the back surface coil portion 2 by heat conduction through the through holes 6. Then, the inner peripheral side conductors 2b1 to 2b4 of the back surface coil portion 2 are cooled by the cooling air sent from the cooling fan 54. Thereby, both the surface coil portion 2a (particularly, the inner peripheral side conductors 2a1 to 2a4) and the back surface coil portion 2b (particularly, the inner peripheral side conductors 2b1 to 2b4) can be cooled.

[0026] As described above, in the induction heating cooker 200 according to the first embodiment, the induction heating coil 100 has the back surface coil portion 2b on the back surface of the substrate 1. Then, the cooling fan 54 serving as the cooling means sends cooling air to the back surface side of the substrate 1 to cool the induction heating coil 100 (mainly the back surface coil portion 2b). For example, if it is desired to supply cooling air between the top plate 52 and the induction heating coil 100, it is necessary to increase the distance between the top plate 52 and the induction heating coil 100 in order to form an air passage. When the distance between the top plate 52 and the induction heating coil 100 is increased, the distance between the induction heating coil 100 and the object to be heated 51 is also increased, so that the linking magnetic flux to the object to be heated 51 is reduced, and the power supplied to the object to be heated 51 and the heating efficiency are decreased. In the induction heating cooker 200 according to the first embodiment, as described above, since there is no need to supply cooling air between the top plate 52 and the induction heating coil 100, the distance between the top plate 52 and the induction heating coil 100 can be made as close as possible, and the linking magnetic flux to the object to be heated 51 can be increased. Therefore, the induction heating cooker 200 according to the first embodiment can supply a large amount of power by the coil portion 2 of the induction heating coil 100 and can improve the heating efficiency.

[0027] Here, the coil portion 2 of the induction heating coil 100 in the first embodiment has the front surface coil portion 2a, and the front surface coil portion 2a and the back surface coil portion 2a are connected by the through hole 6 so that heat transfer can be performed. Therefore, the heat generated by the front surface coil portion 2a can be transmitted to the back surface coil portion 2b. The cooling air sent by the cooling fan 54 to the back surface side of the substrate 1 cools the back surface coil portion 2b, so that the heat generated by the front surface coil portion 2a can be dissipated together with the heat generated by the back surface coil portion 2b, and thus it is not necessary to directly cool the front surface coil portion 2a. Therefore, the front surface coil portion 2a can be cooled without supplying cooling air between the top plate 52 and the induction heating coil 100.

[0028] In particular, in the induction heating cooker 200 according to the first embodiment, the cooling efficiency of the inner peripheral side conductors 2a1 to 2a4 of the surface coil portion 2a and the inner peripheral side conductors 2b1 to 2b4 of the back surface coil portion 2b, where magnetic flux is likely to concentrate in the coil portion 2, is improved. For this reason, the temperature rise of the induction heating coil 100 can be suppressed.

[0029] Here, the induction heating coil 100 in the first embodiment is configured such that the set number of turns is four, and the inner peripheral side conductors 2a1 to 2a4 and the inner peripheral side conductors 2b1 to 2b4 are connected via a plurality of through holes 6. However, the number of turns of the induction heating coil 100 is not limited to this. According to the number of turns of the coil portion 2 and the like, through holes 6 may be provided for conductors of one turn or more. Further, through holes 6 may be provided not only on the inner peripheral side of the induction heating coil 100 but also on the outer peripheral side conductors. At this time, for example, the number of through holes 6 per unit area in one turn of the conductor pattern of the coil portion 2 may be made larger in one turn on the inner peripheral side than in one turn on the outer peripheral side. Thereby, it becomes unnecessary to provide through holes 6 more than necessary, and an increase in the manufacturing cost of the substrate 1 and the like can be suppressed.

[0030] <Modification Example of the First Embodiment> FIG. 5 is a partial cross-sectional view of a housing showing another example in the induction heating apparatus according to the first embodiment. In FIG. 3 described above, the cooling fan 54 is disposed below the induction heating coil 100, but it is not limited thereto and can be disposed at other positions. In FIG. 5, the cooling fan 54 is disposed on the outer peripheral side of the induction heating coil 100. And as shown in FIG. 5, a jet duct 55 is provided below the induction heating coil 100. The jet duct 55 includes a plurality of jet holes 56 and is a member that serves as a cooling means for blowing the cooling air sent from the cooling fan 54 from the jet holes 56 toward the back surface coil portion 2b on the back surface of the substrate 1 of the induction heating coil 100.

[0031] For example, the cooling fan 54 sends cooling air into the jet duct 55 so as to be in the direction of the arrow shown in FIG. 5. Next, the cooling air sent to the jet duct 55 is blown upward from the jet holes 56 toward the back coil portion 2b of the induction heating coil 100. Here, the jet holes 56 are arranged in the jet duct 55 at positions where a large amount of cooling air hits near the inner peripheral side conductors 2b1 to 2b4 of the back coil portion 2b.

[0032] Therefore, even if the cooling fan 54 is arranged at the position as shown in FIG. 5, the cooling air can be focused on hitting the inner peripheral side conductors 2b1 to 2b4 of the back coil portion 2b. In this way, by installing the cooling fan 54 below the induction heating coil 100, the cooling air from the cooling fan 54 can be sent to the induction heating coil 100 without directly hitting the induction heating coil 100. For this reason, for example, the cooling air sent from the cooling fan 54 can pass through heat generating objects other than the induction heating coil 100, such as an inverter circuit and a heat sink provided in the inverter circuit, and then pass through the induction heating coil 100 after being cooled. For this reason, the cooling fan 54 can send cooling air that serves both for cooling the induction heating coil 100 and for cooling other heat generating objects, and an efficient structure can be realized.

[0033] FIG. 6 is a partial cross-sectional view of a housing showing another example in the induction heating device according to the first embodiment. The induction heating cooker 200 in FIG. 6 includes, inside the housing 53, in addition to the induction heating coil 100 and the cooling fan 54, a magnetic shielding plate 57 below the induction heating coil 100. The magnetic shielding plate 57 is a non-magnetic metal plate made of a non-magnetic metal such as aluminum or copper, for example.

[0034] Also, a heat transfer member 58 is installed in close contact with the induction heating coil 100 and the magnetic shielding plate 57 between the induction heating coil 100 and the magnetic shielding plate 57. The heat transfer member 58 is installed at least directly below the inner peripheral side conductors 2b1 to 2b4 of the back surface coil portion 2b in the induction heating coil 100. The heat transfer member 58 is made of a non-conductive material. Although not particularly limited, if, for example, an elastic material is applied as the heat transfer member 58, the adhesion with the induction heating coil 100 and the magnetic shielding plate 57 can be further improved. The elastic material is, for example, silicone or the like.

[0035] Also, a cooling fan 54 and guide vanes (not shown) are arranged so that the cooling air output from the cooling fan 54 is sent along the surface on the lower surface side of the magnetic shielding plate 57. When the magnetic shielding plate 57 is provided below the induction heating coil 100 in this way, the shielding ring 4 installed on the induction heating coil 100 may not be provided.

[0036] Next, the effects of having the magnetic shielding plate 57 as shown in FIG. 6 will be described. By providing the magnetic shielding plate 57 below the induction heating coil 100, the leakage magnetic flux released outside the housing 53 of the induction heating cooker 200 can be reduced. Furthermore, the magnetic shielding plate 57 can serve as a heat sink for cooling the induction heating coil 100. For this reason, the heat generated due to loss from the surface coil portion 2a of the induction heating coil 100 is transferred to the back surface coil portion 2b through the through holes 6, and together with the heat generated in the back surface coil portion 2b, it is transferred to the magnetic shielding plate 57 through the heat transfer member 58. The heat transmitted to the magnetic shielding plate 57 is cooled by the cooling air sent from the cooling fan 54.

[0037] Therefore, by transferring the heat generated in the coil portion 2 of the induction heating coil 100 to the magnetic shielding plate 57 having a larger area compared to the conductors of the coil portion 2, the heat dissipation area can be expanded. For this reason, the cooling performance of the induction heating coil 100 can be improved. As a result, it is possible to achieve miniaturization of the cooling fan 54, quieting by reducing the air volume of the cooling fan 54, and the like.

[0038] Embodiment 2 FIG. 7 is a plan view showing an example of the induction heating coil according to Embodiment 2. FIG. 7 is a view of the back surface of the substrate 1. In FIG. 7, members and the like to which the same reference numerals as those in FIG. 2 and the like are attached perform the same functions as those described in Embodiment 1. Here, in FIG. 7, for the sake of convenience, the magnetic body 5 is not shown. As shown in FIG. 7, the induction heating coil 110 in Embodiment 2 is different from the induction heating coil 100 in Embodiment 1 in that the jumper wire 7 is partially arranged in the coil portion 2. Hereinafter, the induction heating coil 110 in Embodiment 2 will be described centering on the differences from the induction heating coil 100 in Embodiment 1.

[0039] As also described in Embodiment 1, the coil portion 2 in Embodiment 2 is also configured by a pattern in which a conductor is wound a plurality of times in a spiral shape on the substrate 1. And in the coil portion 2, the inner peripheral side conductors 2a1 to 2a4 formed on the inner peripheral side and the inner peripheral side conductors 2b1 to 2b4 are electrically connected by a plurality of through holes 6. In the induction heating coil 110 in Embodiment 2, between two adjacent through holes 6 in the winding direction of the conductor, they are electrically connected by the jumper wire 7. The jumper wire 7 is usually a U-shaped metal lead wire used when electrically connecting separated conductor patterns on a printed circuit board.

[0040] For example, in FIG. 7, through holes 6a, 6b, 6c, and 6d are provided in the substrate 1 corresponding to the positions where the inner peripheral side conductors 2b4 of the back surface coil portion 2b disposed on the back surface of the substrate 1 of the induction heating coil 110 are located. And a jumper wire 7a is mounted between the through hole 6a and the through hole 6b adjacent in the winding direction. Also, a jumper wire 7b is mounted between the through hole 6c and the through hole 6d adjacent in the winding direction. Thus, a plurality of jumper wires 7 are mounted on the through holes 6 along the winding direction in the inner peripheral side conductors 2a1 to 2a4 and the inner peripheral side conductors 2b1 to 2b4 of the coil portion 2. The jumper wire 7 is electrically connected to the through hole 6 and the conductors of the coil portion by solder.

[0041] FIG. 8 is a schematic cross-sectional view when the induction heating coil according to Embodiment 2 is cut along the winding direction of the conductors of the coil portion. As shown in FIG. 8, it is desirable that the jumper wire 7 be mounted on the induction heating coil 110 with a gap a of a predetermined interval so as not to be in close contact with the conductors of the back surface coil portion 2b except at the through hole 6.

[0042] Next, the effects of providing jumper wires 7 in six through-holes 6 will be described. As described in the first embodiment, the combined magnetic flux of the magnetic flux generated in the coil part 2 is directed from the outer peripheral side of the coil part 2 toward the center of the coil part 2. For this reason, in the coil part 2, the conductors on the inner peripheral side have high eddy current loss and tend to have a high conductor temperature. The induction heating coil 110 in the second embodiment has jumper wires 7 mounted on the inner peripheral side conductors 2a1 to 2a4 and the inner peripheral side conductors 2b1 to 2b4 where the conductor temperature becomes high. Therefore, a part of the current flowing through the conductors of the coil part 2 can be diverted to the jumper wires 7, and the current flowing through the conductors of the coil part 2 can be decreased. Thereby, in the coil part 2, the conductor temperature on the inner peripheral side can be reduced. Also, by mounting the jumper wires 7 with a gap a therebetween, the cooling air sent from the cooling fan 54 flows through the gap a. For this reason, the conductors of the coil part 2 and the jumper wires 7 can be efficiently cooled respectively.

[0043] Further, the induction heating coil 110 in the second embodiment can transfer the heat generated in the conductors of the surface coil part 2a to the back surface coil part 2b and the like by the copper foil plating provided on the inner wall of the through-hole 6 and the jumper wires 7. For this reason, compared with the case where heat transfer is performed only through the through-holes 6, the induction heating coil 110 has an improved thermal conductivity and can transfer more heat to the back surface side of the substrate 1. Thereby, even if cooling air is not actively supplied to the surface of the induction heating coil 110, the temperature rise of the conductors in the surface coil part 2a can be suppressed. Therefore, the distance between the top plate 52 and the induction heating coil 110 can be made as close as possible, and the linked magnetic flux to the object to be heated 51 can be increased. Therefore, the induction heating cooker 200 can supply a large amount of power by the coil part 2 and can improve the heating efficiency.

[0044] Embodiment 3. FIG. 9 is a partial plan schematic view showing an example of the induction heating coil according to Embodiment 3. In FIG. 9, members and the like with the same reference numerals as in FIG. 2 and the like perform the same functions as those described in Embodiment 1. As shown in FIG. 9, the induction heating coil 120 in Embodiment 3 is different from the induction heating coil 100 in Embodiment 1 in that it has a non-resist portion 8 where the solder resist is not partially applied. Hereinafter, the induction heating coil 120 in Embodiment 3 will be described centering on the differences from the induction heating coil 100 in Embodiment 1.

[0045] As also described in Embodiment 1, the coil portion 2 in Embodiment 3 is also configured on the substrate 1 in a pattern in which a conductor is wound in a spiral shape a plurality of times. Then, a solder resist is applied to the coil portion 2. As described above, the solder resist insulates and protects the coil portion 2. Here, in Embodiment 3, the induction heating coil 120 has a non-resist portion 8 where the solder resist is not applied to the inner peripheral side conductors 2b1 to 2b4 formed on the inner peripheral side in the back surface coil portion 2b. The non-resist portion 8 is provided in a portion surrounding the periphery of the through hole 6. Further, solder is attached to the non-resist portion 8 by soldering.

[0046] Next, the effects of providing the non-resist portion 8 in the back coil portion 2b will be described. As described in Embodiment 1, the combined magnetic flux of the magnetic flux generated in the coil portion 2 is directed from the outer peripheral side of the coil portion 2 toward the center of the coil portion 2. For this reason, in the coil portion 2, the conductor on the inner peripheral side has a high eddy current loss and the conductor temperature tends to be high. The induction heating coil 120 in Embodiment 3 has a part of the conductor on the inner peripheral side where the conductor temperature becomes high as a non-resist portion 8 to which solder is attached without providing a solder resist. In the non-resist portion 8, since solder having conductivity is attached, the cross-sectional area of the conductor in the non-resist portion 8 is substantially increased. For this reason, a part of the current flowing through the back coil portion 2b flows into the solder, and by reducing the current density, the current flowing through the copper foil portion of the back coil portion 2b can be reduced. Thereby, the temperature of the conductor pattern provided on the inner peripheral side of the induction heating coil 120 can be reduced. Further, in the non-resist portion 8, since the cooling air directly hits the solder which is a conductor and takes away the heat, the cooling efficiency of the induction heating coil 120 can be improved.

[0047] Further, in the induction heating coil 120 in Embodiment 3, the portion where the through hole 6 is provided is the non-resist portion 8. For this reason, the distance in the circumferential direction of the back coil portion 2b between the through hole 6 that transmits the heat generated by the surface coil portion 2a and the non-resist portion 8 can be shortened. The heat dissipation efficiency is improved, and the temperature of the conductor in the coil portion 2 can be lowered.

[0048] Here, although not shown, similar to the induction heating coil 110 described in Embodiment 2, jumper wires 7 may be provided in the through holes 6 adjacent along the circumferential direction. Thereby, the heat dissipation efficiency can be further improved, and the temperature of the conductor in the coil portion 2 can be lowered. Also, for the surface coil portion 2a of the induction heating coil 120, for example, the non-resist portion 8 may be provided on the inner peripheral side conductors 2a1 to 2a4. In this case, heat can be efficiently dissipated from both sides of the induction heating coil 120.

[0049] Here, the induction heating coil 120 in Embodiment 3 was set to have 4 preset turns, and the non-resist portions 8 were provided on the inner peripheral side conductors 2b1 to 2b4. However, the present invention is not limited to this. Depending on the number of turns of the coil portion 2 or the like, the non-resist portions 8 may be provided for conductors having one or more turns. Further, the non-resist portions 8 may be provided not only on the inner peripheral side of the induction heating coil 120 but also on the outer peripheral side conductors.

[0050] Embodiment 4. FIG. 10 is a partial cross-sectional view showing the positional relationship of the induction heating coil in the housing of the induction heating cooker according to Embodiment 4. In FIG. 10, members and the like denoted by the same reference numerals as in FIG. 3 and the like perform the same functions as those described in Embodiment 1. The induction heating cooker 200 according to Embodiment 4 is different from Embodiment 1 in that it has an induction heating coil 130 using two substrates 1 each having a coil portion 2 on one side. Hereinafter, Embodiment 4 will be described centering on the differences from Embodiment 1.

[0051] The induction heating coil 130 in Embodiment 4 is composed of two printed circuit boards. On each of the two printed circuit boards, an electric circuit or wiring pattern is formed by a printing technique using a conductor such as copper foil only on one side. The induction heating coil 130 in Embodiment 4 has a first substrate 1a located on the upper side and closer to the object to be heated 51 (top plate 52), and a second substrate 1b located below the first substrate 1a. The first substrate 1a and the second substrate 1b each have the coil portion 2, the first connector 3a (not shown), the second connector 3b (not shown), and the shield ring 4 described in Embodiment 1. Further, the induction heating coil 130 has the magnetic body 5 described in Embodiment 1 below the second substrate 1b provided on the lower side. Here, in Embodiment 4, the coil portion 2 disposed on the first substrate 1a is referred to as the first coil portion 2c, and the coil portion 2 disposed on the second substrate 1b is referred to as the second coil portion 2d. The shield ring 4 may be provided on only one of the first substrate 1a or the second substrate 1b.

[0052] The first substrate 1a and the second substrate 1b are, for example, paper phenolic substrates in which a paper base material is impregnated with a phenolic resin. Coil portions 2 are formed on the back surfaces of the first substrate 1a and the second substrate 1b, respectively. Further, as shown in FIG. 10, the first substrate 1a and the second substrate 1b are not in close contact with each other, and a predetermined gap is provided therebetween. Also, the first substrate 1a and the second substrate 1b are electrically connected to each other via a lead wire or a connector (not shown). Thereby, for example, the first coil portion 2c provided on the first substrate 1a and the second coil portion 2d provided on the second substrate 1b are electrically connected in series or in parallel.

[0053] The cooling fan 54 is, for example, an axial flow fan. The cooling fan 54 blows cooling air in the direction of the arrow in FIG. 10, and is arranged together with a guide vane (not shown) or the like so that the cooling air flows through a path passing between the first substrate 1a and the second substrate 1b and a path passing through the lower surface side of the second substrate 1b.

[0054] Next, the effect of configuring the induction heating coil 130 with two printed circuit boards will be described in comparison with the case where the coil portions 2 are formed on both surfaces of a single substrate 1. For example, when the coil portions 2 are formed on both surfaces of the substrate 1, the coil portion 2 on the front surface side is provided at a position facing the bottom surface of the pan, which is the object to be heated 51. In order to improve the heating efficiency, the induction heating coil 120 is installed close to the top plate 52 constituting the induction cooker 200. Therefore, it is difficult to flow cooling air between the top plate 52 and the induction heating coil 100. In the induction cooker 200 according to the fourth embodiment, in the induction heating coil 130, two substrates 1 are used, and the first coil portion 2c and the second coil portion 2d are arranged on the back surfaces of the first substrate 1a and the second substrate 1b, respectively. Then, the cooling fan 54 is configured to flow cooling air between the first substrate 1a and the second substrate 1b and on the back surface side of the second substrate 1b. For this reason, the first substrate 1a can be brought closer to the top plate 52, and the conductor patterns of the first coil portion 2c and the second coil portion 2d can be cooled without reducing the heating efficiency. Here, in FIG. 10, the second substrate 1b is configured to have the second coil portion 2d on the back surface side, but the present invention is not limited to this. For example, the second substrate 1b may be configured to have the second coil portion 2d on the front surface and cool the coil portion 2 by flowing cooling air between the first substrate 1a and the second substrate 1b.

[0055] <Modification Example of Embodiment 4> FIG. 11 is a partial cross-sectional view of the inside of a housing when an induction heating coil according to a modification of Embodiment 4 is installed in an induction heating cooker. FIG. 12 is a plan view showing a second substrate on the lower side in the induction heating coil according to the modification of Embodiment 4. In the induction heating coil 140 of the modification in Embodiment 4, the lower second substrate 1b has a through hole serving as a ventilation hole 9 between the inner peripheral side conductors 2d1 to 2d4 in the coil portion 2. The cooling fan 54 is, for example, an axial flow fan. As shown in FIG. 11, the cooling fan 54 is disposed below the induction heating coil 140 within the housing 53, and the air flow direction is such that, as indicated by the arrow in FIG. 11, it blows upward toward the back surface of the second substrate 1b of the induction heating coil 140. Thereby, the cooling air is blown upward toward the second substrate 1b directly above, and the conductors in the second coil portion 2d of the second substrate 1b are cooled. The cooling air passes through the ventilation hole 9 provided in the second substrate 1b and cools the conductors in the first coil portion 2c of the first substrate 1a located above the second substrate 1b.

[0056] As described above, in the induction heating coil 140 according to the modification of Embodiment 4, the ventilation hole 9 is provided in the second substrate 1b between the inner peripheral side conductors 2d1 to 2d4 of the second coil portion 2d. By setting the air flow direction of the cooling air from the cooling fan 54 to blow upward against the induction heating coil 140, the inner peripheral side conductors of the first coil portion 2c and the second coil portion 2d disposed on the first substrate 1a and the second substrate 1b can be preferentially cooled by the cooling air. Therefore, it is possible to preferentially reduce the temperature of the inner peripheral side conductor where magnetic flux is concentrated and the conductor temperature of the coil portion 2 becomes high. Here, in FIG. 11, the cooling fan 54 is located below the induction heating coil 140 and directly sends cooling air to the induction heating coil 140, but the present invention is not limited to this. Even when the cooling fan 54 is not located below the induction heating coil 140, guide vanes or the like may be appropriately provided to set the air flow direction according to the air flow direction of the cooling fan 54. Further, the cooling fan 54 is not limited to an axial flow fan, and other types of fans may be used. Also, although the cooling means has been described as including the cooling fan 54 and performing air cooling, other cooling means such as water cooling may be used.

[0057] Hereinafter, aspects of the present disclosure will be collectively described as appendices.

[0058] (Appendix 1) A substrate having a front surface that is a surface facing the object to be heated and a back surface that is the surface opposite to the front surface, and a back surface coil portion in which a conductor is wound a plurality of times on the back surface of the substrate to form a spiral conductor pattern, an induction heating coil for heating the object to be heated, Cooling means for cooling the induction heating coil on the back surface side of the substrate An induction heating cooker comprising: (Appendix 2) The induction heating coil has a front surface coil portion on the front surface of the substrate, in which the conductor is wound a plurality of times to have a spiral conductor pattern, The substrate has a plurality of through holes that electrically connect between the conductors of the front surface coil portion and the back surface coil portion that are wound within a set number of turns from the center of the winding among the conductors wound in the front surface coil portion and the back surface coil portion. The induction heating cooker according to Appendix 1. (Appendix 3) The number of through holes per unit area in the conductor is larger in the conductor wound inside than in the conductor wound outside. The induction heating cooker according to Appendix 2. (Appendix 4) The induction heating coil has a jumper wire that electrically connects between two adjacent through holes in the winding direction. The induction heating cooker according to Appendix 2. (Appendix 5) The induction heating coil has a solder resist that covers the conductor, The back surface coil portion has a non-resist portion in which the conductor wound within a set number of turns from the center of the winding among the conductors to be wound is not covered with the solder resist. The induction heating cooker according to Appendix 2. (Appendix 6) The conductor in the non-resist portion is covered with solder. The induction heating cooker according to Appendix 5. (Appendix 7) The induction heating cooker according to Appendix 5 or Appendix 6 having the non-resist portion at the position where the through-hole is installed. (Appendix 8) The induction heating coil is In the back surface coil portion, a heat transfer member installed on the conductor wound within the set turns from the center of winding, and A non-magnetic metal plate installed corresponding to the heat transfer member The induction heating cooker according to Appendix 2 having. (Appendix 9) A first substrate having a front surface that is a surface facing the object to be heated and a back surface that is the opposite surface of the front surface, a first coil portion in which a conductor is wound a plurality of times to form a spiral conductor pattern on the back surface of the first substrate, a second substrate installed at a position facing the back surface of the first substrate, and an induction heating coil having a second coil portion in which a conductor is wound a plurality of times to form a spiral conductor pattern on the second substrate, Cooling means for cooling the induction heating coil And comprising The induction heating cooker in which the first coil portion and the second coil portion are electrically connected. (Appendix 10) The induction heating cooker according to any one of Appendices 1 to 9, wherein the cooling means has a cooling fan that sends cooling air to the induction heating coil. (Appendix 11) The second substrate has a plurality of ventilation holes in a portion where the conductor wound within the set turns from the center of winding among the conductors to be wound is not wound, The induction heating cooker according to Appendix 9, wherein the cooling means has a cooling fan that sends cooling air to the second substrate. (Appendix 12) The cooling means is The induction heating cooker according to Appendix 10 or Appendix 11, having a jet duct that blows the cooling air from the cooling fan toward the back surface side of the substrate of the induction heating coil.

Explanation of reference numerals

[0059] 1 Substrate, 1a First substrate, 1b Second substrate, 2 Coil part, 2a Surface coil part, 2b Back surface coil part, 2c First coil part, 2d Second coil part, 2a1, 2a2, 2a3, 2a4, 2b1, 2b2, 2b3, 2b4, 2d1, 2d2, 2d3, 2d4 Inner peripheral side conductor, 3 Connector, 3a First connector, 3b Second connector, 4 Shield ring, 5 Magnetic body, 6, 6a, 6b, 6c, 6d Through hole, 7, 7a, 7b Jumper wire, 8 Non-resist part, 9 Ventilation hole, 51 Object to be heated, 52 Top plate, 53 Housing, 54 Cooling fan, 55 Jet duct, 56 Jet hole, 57 Anti-magnetic plate, 58 Heat transfer member, 61 Inverter substrate, 62 Operation part, 63 Display part, 100, 100a, 100b, 110, 120, 130, 140 Induction heating coil, 200 Induction heating cooker.

Claims

1. A substrate having a front surface facing the object to be heated and a back surface opposite to the front surface, and a back surface coil portion formed on the back surface of the substrate with a conductor wound multiple times to form a spiral conductor pattern, an induction heating coil for heating the object to be heated, cooling means for cooling the induction heating coil on the back surface side of the substrate, and an induction heating cooker provided with the same.

2. The induction heating coil has a front surface coil portion on the front surface of the substrate, with the conductor wound multiple times to form a spiral conductor pattern, The substrate has a plurality of through holes for electrically connecting between the conductors of the front surface coil portion and the back surface coil portion wound within a set number of turns from the center of winding among the conductors wound in the front surface coil portion and the back surface coil portion. The induction heating cooker according to claim 1.

3. The induction heating cooker according to claim 2, wherein the number of through holes per unit area in the conductor is greater in the conductor wound closer to the inside than in the conductor wound closer to the outside.

4. The induction heating coil according to claim 2 has jumper wires for electrically connecting between two adjacent through holes in the winding direction.

5. The induction heating coil has a solder resist covering the conductor, The back surface coil portion has a non-resist portion in the conductor wound within a set number of turns from the center of winding among the conductors to be wound, where the conductor is not covered with the solder resist. The induction heating cooker according to claim 2.

6. The conductor in the non-resist portion is covered with solder. The induction heating cooker according to claim 5.

7. The induction heating cooker according to claim 5 or claim 6, having the non-resist portion at the position where the through hole is provided.

8. The induction heating coil, in the back surface coil portion, has a heat transfer member installed on the conductor wound within a set number of turns from the center of winding, and a non-magnetic metal plate installed corresponding to the heat transfer member. The induction heating cooker according to claim 2.

9. The cooling means has a cooling fan for sending cooling air to the induction heating coil. The induction heating cooker according to any one of claims 1 to 6 or claim 8.

10. The cooling means, The induction heating cooker according to claim 9, further comprising a jet duct that blows the cooling air from the cooling fan toward the back surface side of the substrate of the induction heating coil.

11. An induction heating coil including: a first substrate having a front surface that is a surface facing an object to be heated and a back surface that is a surface opposite to the front surface; a first coil portion formed by winding a conductor a plurality of times around the back surface of the first substrate to form a spiral conductor pattern; a second substrate disposed at a position facing the back surface of the first substrate; and a second coil portion formed by winding a conductor a plurality of times around the second substrate to form a spiral conductor pattern, cooling means for cooling the induction heating coil, and an induction heating cooker in which the first coil portion and the second coil portion are electrically connected.

12. The second substrate has a plurality of ventilation holes in a portion of the conductor to be wound where the conductor wound within a set number of turns from the center of winding is not wound. The induction heating cooker according to claim 11, wherein the cooling means includes a cooling fan that sends cooling air to the second substrate.

13. The cooling means includes a jet duct that blows the cooling air from the cooling fan toward the back surface side of the second substrate of the induction heating coil, according to claim 12.

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