Induction heating coil and induction heating cooker equipped with the same

Abstract

To provide an induction heating coil and an induction heating cooker equipped with the same coil that prevents a short circuit between conductors in the radial direction of a coil.SOLUTION: An induction heating coil heats an object to be heated and includes a coil portion in which a conductor is wound in a spiral shape, and a coil base that has a plurality of grooves formed at intervals in the radial direction of the coil portion, accommodates the conductors in the grooves, and keeps the radial distance between the conductors constant by side wall portions that form the grooves.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an induction heating coil that heats an object to be heated and an induction heating cooker including the same. [Background technology]

[0002] 2. Description of the Related Art Conventionally, an induction heating coil having a film to which a spirally wound metal foil is attached is known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-42696 Summary of the Invention [Problem to be solved by the invention]

[0004] The induction heating coil in Patent Document 1 is configured in such a way that a spirally wound metal foil is attached to a film, so when the film deforms, adjacent metal foil pieces in the radial direction of the winding may come into contact with each other, causing a short circuit.

[0005] The present disclosure has been made to solve the above-mentioned problems, and provides an induction heating coil that prevents conductors from shorting out in the radial direction of the coil, and an induction heating cooker equipped with the same. [Means for solving the problem]

[0006] The induction heating coil of the present disclosure is an induction heating coil for heating an object to be heated, and includes a coil portion in which a conductor is wound in a spiral shape, and a coil base having a plurality of groove portions formed at intervals in the radial direction of the coil portion, in which the conductors are accommodated, and in which the distance between the conductors in the radial direction is kept constant by side wall portions that form the grooves.

[0007] An induction heating cooker according to the present disclosure includes the induction heating coil described above. Effect of the Invention

[0008] According to the present disclosure, the conductor of the spiral coil portion is accommodated in a plurality of grooves formed at intervals in the radial direction of the coil base. Since side walls that form the grooves that accommodate the conductors are provided between the radial conductors, insulation between the conductors is ensured. Therefore, it is possible to prevent the conductors adjacent in the radial direction from coming into contact with each other due to deformation of the induction heating coil, resulting in a short circuit. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is an exploded perspective view showing an example of an induction heating coil 100 according to a first embodiment. [Diagram 2] 1 is a perspective view showing an example of a first terminal portion 1a in an induction heating coil 100 according to embodiment 1. FIG. [Diagram 3] 2 is a perspective view showing the back surface of the induction heating coil 100 shown in FIG. [Figure 4] 4 is a plan view showing a second fixing method for the coil portion 1 in the induction heating coil 100 according to the first embodiment. FIG. [Diagram 5] FIG. 5 is a cross-sectional view taken along line AA in FIG. [Figure 6] 4 is a partial plan view showing a third fixing method for the coil portion 1 in the induction heating coil 100 according to the first embodiment. FIG. [Figure 7] 10 is a partial perspective view showing a fourth fixing method for the coil portion 1 in the induction heating coil 100 according to the first embodiment. FIG. [Figure 8] 3 is a perspective view showing another example of the configuration of the first terminal 1a and the second terminal 1b in the induction heating coil 100 according to the first embodiment. FIG. [Figure 9] 1 is a plan view showing an example of an induction heating coil 110 according to a first modification of the first embodiment. FIG. [Figure 10] 10 is a perspective view showing a coil portion 1 of the induction heating coil 110 shown in FIG. [Figure 11] 10 is a diagram showing a schematic cross section taken along line BB in FIG. 9. FIG. [Figure 12] 10 is a partial cross-sectional view showing an induction heating coil 120 according to a second modification of the first embodiment. FIG. [Figure 13] FIG. 11 is a perspective view showing an example of an external appearance of an induction heating cooker 200 according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An embodiment of the induction heating coil and the induction heating cooker having the same according to the present disclosure will be described with reference to the drawings. In each drawing, the same reference numerals are used to denote the same or equivalent configurations, and this is common throughout the entire specification. The forms of the components shown in the entire specification are merely examples and are not limited to the description in the specification. In each drawing, the relationship between the sizes of the components may differ from the actual relationship. Furthermore, for convenience of explanation, two arrows defining the directions are shown in the drawings. The vertical direction is indicated by the Z1 arrow, and the opposite direction to the vertical direction is indicated by the Z2 arrow.

[0011] Embodiment 1 The configuration of the induction heating coil of the present embodiment 1 will be described. FIG. 1 is an exploded perspective view showing an example of an induction heating coil 100 according to the embodiment 1. The induction heating coil 100 of the present embodiment 1 is provided in, for example, an induction heating cooker 200 shown in FIG. 13. The induction heating coil 100 is applied to an induction heating cooker 200 such as an IH (Induction Heating) cooking heater that heats an object to be heated 6 placed on a top plate 9 shown in FIG. 13. The object to be heated 6 is, for example, a cooking utensil such as a metal pan. The configuration of the induction heating cooker 200 shown in FIG. 13 will be described in the embodiment 2.

[0012] The induction heating coil 100 has a coil part 1 and a coil base 4. The coil part 1 has a disk-like shape and is made of a conductor cut into a spiral shape from a metal plate, for example. In the induction heating coil 100 shown in FIG. 1, the surface in the direction of the Z2 arrow is the front surface, and the surface in the direction of the Z1 arrow is the back surface. The front surface of the induction heating coil 100 is the surface facing the heated object 6 in the induction heating cooker 200 shown in FIG. 13. The coil part 1 is accommodated in a conductor accommodating groove 4a formed on the front surface of the coil base 4. The magnetic body 3 is accommodated in a magnetic body accommodating groove 4b formed on the back surface of the coil base 4. A magnetic shielding ring 2 is provided along the outer periphery of the coil base 4. For convenience of explanation, FIG. 1 shows a state in which the coil part 1 and the magnetic body 3 are separated from the coil base 4.

[0013] Each component of the induction heating coil 100 shown in FIG. 1 will be described in detail. First, the coil section 1 will be described. The coil section 1 is disk-shaped in the configuration example shown in FIG. 1, but it does not have to be disk-shaped. The coil section 1 is produced as a seamless single piece by cutting a metal plate material such as copper or aluminum into a spiral shape. The plate material may be an aluminum alloy. As a method for cutting the plate material into a spiral shape, for example, a method of punching the plate material by press processing, and a method of cutting the plate material by laser processing, wire electric discharge processing, or the like can be considered. In the configuration example shown in FIG. 1, the conductor width, which is the radial length of one conductor of the coil section 1, is the same throughout the conductor. In addition, the coil section 1 is configured to be wound in a state where a predetermined interval is maintained between adjacent conductors when viewed in the radial direction from the center of the winding.

[0014] At both ends of the coil unit 1, terminals for attaching lead wires are provided. The coil unit 1 has a first terminal 1a which is a terminal on the inner circumference side and a second terminal 1b which is a terminal on the outer circumference side. As shown in FIG. 1, the first terminal 1a and the second terminal 1b are, for example, rectangular in shape. The first terminal 1a and the second terminal 1b are connected to an inverter board 7 (see FIG. 13) provided in an induction heating cooker 200 shown in FIG. 13 via lead wires (not shown), and a high-frequency current is supplied from the inverter board 7. That is, the coil unit 1 functions as an electric circuit through which a current flows. The coil unit 1 generates a high-frequency magnetic flux by receiving a high-frequency current from the inverter board 7 via the first terminal 1a and the second terminal 1b. The generated magnetic flux is interlinked with the bottom surface of the heated object 6 placed directly above the induction heating coil 100. As a result, an eddy current is generated on the bottom surface of the object 6 to be heated, and Joule heat is generated by the eddy current and the resistance component of the object 6 to be heated, so that the bottom of the object 6 to be heated is heated.

[0015] The first terminal portion 1a and the second terminal portion 1b are integrally formed with the spirally wound conductor. When the coil portion 1 is manufactured, the first terminal portion 1a and the second terminal portion 1b are cut out from the same metal plate together with the spirally wound conductor. As shown in FIG. 1, the first terminal portion 1a and the second terminal portion 1b are provided with a through hole in the center. By threading the inner wall surface of the through hole of the first terminal portion 1a and the second terminal portion 1b, the terminal of the lead wire (not shown) to be connected to the inverter board 7 can be screwed.

[0016] FIG. 2 is a perspective view showing an example of the first terminal 1a in the induction heating coil 100 according to the first embodiment. When the plate thickness of the coil portion 1 is thin, the thread cutting process is facilitated by performing burring or flange processing on the first terminal 1a, which will be described with reference to FIG. 2. As shown in FIG. 2, a cylindrical protrusion 1c is formed on the periphery of the screw hole by performing burring from the lower side to the upper direction (Z2 arrow direction) of the first terminal 1a. The first terminal 1a is easier to thread because the area of ​​the inner wall surface of the cylindrical protrusion 1c is added to the area of ​​the inner wall surface of the through hole compared to the case where only the area of ​​the inner wall surface of the through hole of the plate material is included. In addition, since the protrusion 1c is formed on the upper surface side (Z2 arrow direction) of the first terminal 1a, the lower surface side (Z1 arrow direction) of the first terminal 1a has a flat shape, and therefore the terminal of the lead wire (not shown) can be attached to the lower surface side of the first terminal 1a. 13, the first terminal 1a can be connected to the inverter board 7 arranged below the induction heating coil 100 by a short lead wire (not shown). Note that the second terminal 1b has a similar configuration to the first terminal 1a, and therefore a detailed description thereof will be omitted.

[0017] Next, we will explain the plate thickness of the coil section 1. When a high-frequency current is supplied to the coil section 1 by the inverter board 7, a skin effect is known in which the current flowing through the conductor is concentrated on the surface of the conductor. The skin depth d, which is the depth to which the current penetrates from the surface of the conductor into the inside of the conductor, is expressed by formula (1).

[0018]

number

[0019] In equation (1), f is the frequency of the high-frequency current, μ is the magnetic permeability of the conductor, and σ is the conductivity of the conductor. The skin depth d expressed in equation (1) represents the depth at which the amplitude of the current is 1 / e of that on the conductor surface. In other words, skin depth d represents the depth at which the amplitude of the current is 37% of that on the conductor surface. When skin depth d is doubled, the amplitude of the current attenuates to 13.5%, and when skin depth d is tripled, the amplitude of the current attenuates to 5%.

[0020] Here, if aluminum is used as the material for the coil portion 1 and the driving frequency is 20 kHz, which is above the audible range, the skin depth d is 0.6 mm from formula (1). Doubling 0.6 mm gives 1.2 mm, and tripling 0.6 mm gives 1.8 mm. Making the plate thickness of the coil portion 1 thicker than necessary will not allow the current to penetrate, resulting in increased weight and costs, and will not reduce the resistance of the coil portion 1. On the other hand, if the plate thickness of the coil portion 1 is too thin, it will cause an increase in the resistance value of the coil portion 1, increasing the loss in the coil portion 1 and causing a rise in temperature in the coil portion 1.

[0021] Therefore, considering the relationship between the skin depth d and the amplitude of the current, it is desirable to ensure that the plate thickness of the coil portion 1 is 1.2 mm or more, which is twice the skin depth d. This allows the resistance value of the coil portion 1 to be sufficiently reduced, and the conduction loss to be reduced. On the other hand, it is desirable that the plate thickness of the coil portion 1 is 3.0 mm or less, which is five times the skin depth d. This is because when the plate thickness of the coil portion 1 is five times the skin depth d, the amplitude of the current attenuates to 0.7%, and when it is thicker than this, it can be considered that practically no current flows. Also, even if aluminum or an aluminum alloy, which is cheaper than copper, is used as the plate material of the coil portion 1, it is possible to configure an induction heating coil 100 that suppresses the conduction loss.

[0022] The magnetic shielding ring 2 is formed, for example, in a ring shape from an aluminum plate, and is attached to the coil base 4 so as to surround the outer periphery of the coil section 1. The magnetic shielding ring 2 is provided to reduce leakage magnetic flux emitted to the outside of the housing 8 (see FIG. 13) of the induction heating cooker 200 shown in FIG. 13. Specifically, the magnetic flux generated by the coil section 1 interlinks with the magnetic shielding ring 2, so that an eddy current is generated in the magnetic shielding ring 2 in a direction that cancels the interlinking magnetic flux, thereby reducing the leakage magnetic flux to the surroundings. The magnetic shielding ring 2 may be formed in a ring shape by electrically connecting both ends of the aluminum plate by caulking or the like, or may be formed by cutting out a ring shape from the same plate material as the metal plate from which the coil section 1 is cut out. In the case of cutting out from a metal plate, the amount of material waste generated when forming the coil section 1 can be reduced. FIG. 1 shows the case where the magnetic shielding ring 2 is one turn as an example, but the magnetic shielding ring 2 may be configured to be multiple turns and short-circuited at both ends.

[0023] The magnetic body 3 is made of a ferromagnetic material such as ferrite, and is placed on the back side of the coil section 1. The magnetic body 3 increases the density of the magnetic flux generated around the coil section 1, and increases the power input to the object 6 to be heated. FIG. 3 is a perspective view showing the back side of the induction heating coil 100 shown in FIG. 1. As shown in FIG. 3, a plurality of magnetic bodies 3 are radially arranged from the center of the coil section 1 to the outer periphery on the back side of the coil base 4. Although FIG. 1 and FIG. 3 show a case where the number of magnetic bodies 3 is eight, the number of magnetic bodies 3 is not limited to eight. Each magnetic body 3 is rod-shaped, and is arranged along the radial direction from the center of the coil section 1 so that the longitudinal direction of the rod is parallel to the radial direction of the coil section 1. The shape of the magnetic body 3 is not limited to a rod shape. For example, the magnetic body 3 may be an L-shape in which at least one end in the longitudinal direction rises vertically toward the bottom surface of the object 6 to be heated as shown in FIG. 13. In this configuration, the object 6 to be heated can be heated more efficiently.

[0024] The coil base 4 is an insulating member that holds the coil portion 1, the magnetic shielding ring 2, and the magnetic body 3. As shown in Fig. 3, a magnetic body accommodating groove 4b for accommodating the magnetic body 3 is provided on the back surface of the coil base 4. The magnetic body 3 is fixed to the magnetic body accommodating groove 4b with, for example, an adhesive or the like. As shown in Figs. 1 and 3, a magnetic shielding ring 2 is provided on the outer periphery of the coil base 4 so as to surround the coil portion 1.

[0025] As shown in FIG. 1, the surface of the coil base 4 has a conductor accommodating groove 4a formed in a spiral recess along the pattern shape of the conductor of the coil part 1 as an accommodating part for the coil part 1, and the spiral conductor of the coil part 1 is accommodated in the conductor accommodating groove 4a. The conductor accommodating groove 4a is formed between two side wall parts 4c arranged at a distance in the radial direction. As shown in FIG. 1, a plurality of conductor accommodating groove parts 4a are formed in the radial direction from the center of the winding of the coil part 1. In the coil part 1, the conductors adjacent in the radial direction are kept at a constant distance by the side wall parts 4c of the coil base 4. Therefore, insulation of the conductors adjacent in the radial direction is ensured even if the coil part 1 is not provided with an insulating coating or the like. For example, it is possible to prevent the conductors adjacent in the radial direction from coming into contact with each other and shorting out due to deformation of the coil part 1. In addition, the proximity effect can be suppressed by ensuring the distance between the conductors adjacent in the radial direction. Conventionally, a Litz wire has been used to suppress the proximity effect, but the loss of the coil part 1 can be reduced even if the conductor of the coil part 1 is not made of a Litz wire.

[0026] As shown in FIG. 3, the coil base 4 is configured such that the bottom surface portion located at the bottom surface of the recess of the conductor accommodating groove portion 4a is not partially provided, and the conductor of the coil portion 1 can be visually observed from the back side of the induction heating coil 100. Specifically, on the back side of the coil portion 1, the bottom surface portion of the conductor accommodating groove portion 4a is provided in the portion corresponding to the magnetic body accommodating groove portion 4b of the coil base 4, but the bottom surface portion of the conductor accommodating groove portion 4a is not provided in the portion other than the magnetic body accommodating groove portion 4b, and the portion is penetrated. In this way, the coil base 4 may have a through portion in which a bottom surface portion is not provided in at least a portion of the conductor accommodating groove portion 4a. According to this configuration, in the configuration shown in FIG. 1, by supplying cooling air to the coil portion 1 from below the coil base 4, the back side of the coil portion 1 can be directly cooled through the through portion of the conductor accommodating groove portion 4a. In addition, when the material of the coil base 4 is a resin member, a high heat-resistant resin may be used in accordance with the temperature rise of the coil portion 1. In this case, the induction heating coil 100 can be used in a state where the temperature is higher than that of a conventional induction heating coil formed of a printed wiring board. Therefore, when the cooling unit (not shown) that supplies cooling air to the coil unit 1 is a cooling fan, the cooling fan can be made smaller in size.

[0027] 1 shows a configuration in which the multiple conductor accommodating grooves 4a are provided along one circumferential direction, i.e., over a central angle of 360° of the winding of the conductor in the coil portion 1, but the multiple conductor accommodating grooves 4a may be provided along at least a portion of the circumferential direction. Even in this case, the spiral coil portion 1 formed as a single unit is accommodated in the multiple conductor accommodating grooves 4a along at least a portion of the circumferential direction of the coil base 4, so that it is possible to prevent radially adjacent conductors from coming into contact with each other and shorting out due to deformation of the induction heating coil 100.

[0028] Also, while the side wall 4c is provided for one turn along the circumferential direction, it is sufficient that the side wall 4c is provided for at least a part of the circumferential direction. If the distance between adjacent conductors is secured when viewing the coil portion 1 in the radial direction from the center of the winding, it is not necessary to provide the side wall 4c for one turn of the winding, and the side wall 4c may be provided partially in the circumferential direction.

[0029] In the present embodiment 1, the method of fixing the coil portion 1 is not limited to the method described with reference to Fig. 1 to Fig. 3. Fig. 4 is a plan view showing a second fixing method of the coil portion 1 in the induction heating coil 100 according to the embodiment 1. Fig. 5 is a cross-sectional view taken along the line AA in Fig. 4.

[0030] As shown in Figs. 4 and 5, a claw-shaped conductor pressing portion 4d is provided on the side wall portion 4c of the coil base 4. The conductor pressing portion 4d serves to prevent the coil portion 1 from protruding from the recess of the conductor accommodating groove portion 4a. This can prevent the coil portion 1 from protruding from the conductor accommodating groove portion 4a, thereby preventing contact between the conductors and deformation of the shape of the coil portion 1. As shown in Fig. 5, a protrusion 4f may be provided on a part of the bottom surface of the conductor accommodating groove portion 4a. In the configuration example shown in Figs. 4 and 5, a plurality of conductor pressing portions 4d and a plurality of protrusions 4f are provided along a diameter passing through the center of the winding of the coil portion 1. The protrusion 4f is a cylindrical support member that supports the coil portion 1 by contacting the bottom surface of the conductor of the coil portion 1. The protrusion 4f supports the coil portion 1 with its bottom surface separated from the bottom surface of the conductor accommodating groove portion 4a. As a result, the bottom surface of the coil portion 1 only contacts the upper surface of the protrusion 4f and does not contact the bottom surface of the conductor accommodating groove portion 4a. This allows the contact area between the coil portion 1 and the coil base 4 to be reduced.

[0031] The effect of reducing the contact area between the coil portion 1 and the coil base 4 will be described. In the configuration shown in Fig. 4, cooling air supplied from below the coil base 4 passes between the bottom surface of the conductor accommodating groove portion 4a and the underside of the coil portion 1, so that the coil portion 1 can be efficiently cooled. Note that, in the second fixing method described with reference to Figs. 4 and 5, the claw-shaped conductor pressing portion 4d is used to prevent the coil portion 1 from floating, but the means for preventing the coil portion 1 from floating is not limited to the conductor pressing portion 4d.

[0032] FIG. 6 is a partial plan view showing a third fixing method of the coil portion 1 in the induction heating coil 100 according to the first embodiment. As shown in FIG. 6, the coil portion 1 is fixed to the coil base 4 by a screw 5. In the induction heating coil 100 shown in FIG. 6, a plurality of through holes are formed in the conductor of the coil portion 1. The coil portion 1 is fixed to the coil base 4 by the screw 5 penetrating each of the plurality of through holes. In this configuration, if the conductor width of the coil portion 1 is so narrow that it is difficult to provide a through hole in the conductor, as shown in FIG. 6, the conductor width of the portion fixed by the screw 5 may be widened to provide a through hole in the conductor. It is desirable that the material of the screw 5 is a non-magnetic metal that is not easily induced heated. The non-magnetic metal is, for example, aluminum.

[0033] FIG. 7 is a partial perspective view showing a fourth fixing method of the coil part 1 in the induction heating coil 100 according to the first embodiment. As shown in FIG. 7, the coil part 1 is provided with a plurality of through holes 1d. The coil base 4 is provided with protruding positioning pins 4g at the locations where the through holes 1d of the coil part 1 are located. Each positioning pin 4g is provided on the bottom surface of the conductor accommodating groove 4a shown in FIG. 1. According to this configuration, in the work of assembling the coil part 1 to the coil base 4, it becomes easy for the worker to align the coil part 1 to the coil base 4, and the manufacturing process can be simplified. In addition, a conductor fixing part 4h as shown in FIG. 7 may be provided as a return part at the tip part of the positioning pin 4g. The conductor fixing part 4h functions as a removal prevention part that prevents the conductor of the coil part 1 from being removed from the coil base 4. In this way, the positioning pin 4g may also serve to prevent the coil part 1 from coming off in addition to the role of alignment. This allows the number of parts and the work process to be reduced compared to the case of fixing by screwing. Note that, with reference to Figure 7, an example has been described in which the positioning pin 4g is integrated with the coil base 4, but the positioning pin 4g may be prepared as a separate piece from the coil base 4 and installed on the coil base 4.

[0034] Next, the connection between the first terminal 1a and the second terminal 1b of the coil portion 1 and the lead wire will be described in detail. As a specific example, a case will be described in which aluminum is used as the material of the coil portion 1, copper is used as the material of the lead wire, and copper is used as the material of the screw connection terminal provided at the end of the lead wire. It is generally known that when moisture is present at the joint between copper and aluminum, corrosion occurs due to the potential difference between the different metals. Therefore, in the present embodiment 1, at least the first terminal 1a and the second terminal 1b of the coil portion 1 may be plated to cover the surfaces of the first terminal 1a and the second terminal 1b with a plating material. The plating material is a corrosion-resistant metal. The corrosion-resistant metal is preferably, for example, nickel or tin. This makes it possible to connect the first terminal 1a and the second terminal 1b to the lead wire while avoiding direct contact between aluminum and copper.

[0035] Alternatively, when an aluminum screw connection terminal is used as the screw connection terminal, the screw connection terminal may be plated with a plating material and connected to a copper lead wire. The plating material is a corrosion-resistant metal. In this case, the first terminal portion 1a, the second terminal portion 1b and the screw connection terminal are all made of aluminum, so there is no need to plate the coil portion 1 including the first terminal portion 1a and the second terminal portion 1b. The screw connection terminal is plated in order to prevent corrosion of the screw connection terminal since the lead wire is made of copper.

[0036] In the present embodiment 1, Figs. 1 and 2 show a case where the first terminal 1a and the second terminal 1b are configured so that the rectangular surfaces of the first terminal 1a and the second terminal 1b are flush with the coil unit 1, but the present invention is not limited to this configuration. Fig. 8 is a perspective view showing another configuration example of the first terminal 1a and the second terminal 1b in the induction heating coil 100 according to the embodiment 1. As shown in Fig. 8, the first terminal 1a and the second terminal 1b may be bent so that the first terminal 1a and the second terminal 1b are parallel to the vertical direction (the direction of the Z1 arrow) with respect to the coil unit 1 that is horizontally arranged. By configuring the first terminal 1a and the second terminal 1b as shown in Fig. 8, it becomes easy to draw out the lead wires from the respective terminals of the first terminal 1a and the second terminal 1b. For example, when the inverter board 7 shown in Fig. 13 is installed below the induction heating coil 100, the inverter board 7 and the induction heating coil 100 can be electrically connected with a short lead wire.

[0037] (Variation 1) With reference to Fig. 2, the case has been described in which all conductor intervals and all conductor widths in coil portion 1 are the same, but the conductor intervals are not limited to being the same, and the conductor widths are not limited to being the same. Fig. 9 is a plan view showing an example of induction heating coil 110 according to Modification 1 of Embodiment 1. Fig. 10 is a perspective view showing coil portion 1 of induction heating coil 110 shown in Fig. 9. As shown in Figs. 9 and 10, coil portion 1 may have conductors 1e, 1f, 1g, and 1h whose conductor widths are wider than the conductor widths of the other conductors.

[0038] In the coil section 1 shown in Figs. 9 and 10, the conductor arranged on the inner periphery side closer to the center of the coil section 1 than the conductor 1e is referred to as the inner periphery conductor. The conductors 1e to 1h arranged on the outer periphery side than the inner periphery conductor are referred to as intermediate conductors, and the conductor arranged on the outer periphery side than the intermediate conductor is referred to as the outer periphery conductor. In the coil section 1 shown in Figs. 9 and 10, the outer periphery conductor is two conductors. The inner periphery conductor and the outer periphery conductor have the same conductor width and the same conductor spacing. Each of the intermediate conductors 1e to 1h not only has a conductor width wider than the conductor width of the inner periphery conductor and the outer periphery conductor over one revolution, but also has a conductor spacing in the radial direction narrower than the spacing between the inner periphery conductor and the outer periphery conductor.

[0039] Fig. 11 is a diagram showing a schematic cross section along line BB in Fig. 9. Fig. 11 shows a schematic cross section of the right-hand region from the center of induction heating coil 110 using coil section 1 shown in Fig. 10. The dashed line in Fig. 11 indicates the center of induction heating coil 110. For ease of explanation, Fig. 11 shows a case where object 6 to be heated, which is the object to be heated by induction heating coil 110, is placed. The flow of magnetic flux in induction heating coil 110 will be explained with reference to Fig. 11. The flow of magnetic flux is indicated by dashed arrows.

[0040] As shown in FIG. 11, the composite magnetic flux of the magnetic flux generated by the coil unit 1 is generated to describe a large ellipse passing through the inner and outer circumferential sides of the coil unit 1. Therefore, a large amount of magnetic flux is interlinked with the inner and outer conductors of the coil unit 1. In addition, since magnetic flux flows in and out of the longitudinal ends of the magnetic body 3, the conductor near the end of the magnetic body 3 is more likely to be induction heated. Therefore, by narrowing the conductor width of the inner and outer conductors of the coil unit 1 and ensuring a gap between adjacent conductors in the radial direction, the magnetic flux interlinked with the conductor can be reduced, and the conductor can be prevented from being induction heated.

[0041] Also, when viewed from the top of the induction heating coil 110, the magnetic flux flows radially, so the magnetic flux density tends to be higher toward the inner circumference of the coil section 1. On the other hand, the intermediate conductor of the coil section 1 has less interlinking magnetic flux. For example, the magnetic flux density is particularly low near the conductors 1e to 1h, which are intermediate conductors, so that the vicinity of the intermediate conductors is less susceptible to induction heating. Therefore, compared to the first conductor, which is the inner circumference conductor, in the second conductor, which is the intermediate conductor, the interval between adjacent conductors in the radial direction is narrowed and the conductor width in the radial direction is widened, so that the electrical resistance of the conductor can be reduced. This allows the conduction loss of the coil section 1 to be reduced.

[0042] (Variation 2) Fig. 12 is a partial cross-sectional view showing induction heating coil 120 according to Modification 2 of Embodiment 1. The dashed dotted line shown in Fig. 12 is the center line of induction heating coil 120. Fig. 12 shows a cross section of the induction heating coil to the right of the center line. A plan view of induction heating coil 120 of Modification 2 is omitted because it has a similar configuration to induction heating coil 100 shown in Fig. 4 except that conductor pressing portion 4d is not provided. Induction heating coil 120 of Modification 2 differs from induction heating coil 100 shown in Fig. 1 in the cross-sectional shape of coil portion 1.

[0043] The coil portion 1 shown in FIG. 1 is produced by cutting out a metal plate, so that the cross-sectional shape of the coil portion 1 is rectangular. In contrast, in the second modification, the coil portion 1 is produced by, for example, a single wire, which is a single conductor wire of aluminum or copper. Therefore, as shown in FIG. 12, the cross-sectional shape of the coil portion 1 is circular. In the first modification, as in the configuration shown in FIG. 1, the coil base 4 is provided with a spiral conductor accommodating groove portion 4a. The coil portion 1 of the single wire is installed in the recess of the conductor accommodating groove portion 4a so that the conductors adjacent in the radial direction are kept at a constant interval by the side wall portion 4c of the conductor accommodating groove portion 4a. With this configuration, for example, it is possible to prevent the conductors from coming into contact with each other due to deformation of the coil portion 1, resulting in a short circuit. In addition, the proximity effect can be suppressed by ensuring the distance between the conductors adjacent in the radial direction. Conventionally, a Litz wire has been used to suppress the proximity effect, but the loss of the coil portion 1 can be reduced even without using a Litz wire as the conductor of the coil portion 1.

[0044] According to the second modification, a solid wire is used for the coil portion 1, which allows for more effective use of materials than when the coil portion is formed by cutting it out of a metal plate. Cutting out a metal plate results in some material being wasted, but with a solid wire, only the required amount of conductor wire can be used to form the coil portion 1. Note that the installation of the magnetic shielding ring 2 and the magnetic body 3 on the coil base 4 is similar to the configuration described with reference to Fig. 1, and therefore a detailed description thereof will be omitted.

[0045] The induction heating coil of the first embodiment has a coil section 1 in which a conductor is wound in a spiral shape, and a coil base 4 having a plurality of conductor accommodating grooves 4a formed at intervals in the radial direction of the coil section 1. The coil base 4 accommodates the conductors in the conductor accommodating grooves 4a, and keeps the radial distance between the conductors constant by means of side wall sections 4c that form the conductor accommodating grooves 4a.

[0046] According to the first embodiment, the conductor of the spiral coil portion 1 is accommodated in a plurality of conductor accommodating grooves 4a formed at intervals in the radial direction of the coil base 4. Since the side wall portions 4c forming the conductor accommodating grooves 4a for accommodating the conductors are provided between the radial conductors, insulation between the conductors is ensured. Therefore, it is possible to prevent the conductors adjacent to each other in the radial direction from coming into contact with each other due to deformation of the induction heating coil 100, resulting in a short circuit.

[0047] Embodiment 2 Fig. 13 is a perspective view showing an example of the appearance of the induction heating cooker 200 according to embodiment 2. Fig. 13 shows the induction heating cooker 200 with the top plate 9 removed from the induction heating cooker 200 in order to make it easier to see the inside of the induction heating cooker 200. As shown in Fig. 13, the induction heating cooker 200 includes a housing 8, a top plate 9, an induction heating coil 130a and an induction heating coil 130b, an inverter board 7, an operation unit 10, and a display unit 11.

[0048] The housing 8 contains the induction heating coils 130a and 130b, the inverter board 7, the operation unit 10, the display unit 11, lead cables (not shown), and a connector (not shown), etc. The top plate 9 is a plate on which the object to be heated 6 is placed, and is made of a non-metallic material such as heat-resistant glass or ceramic. Fig. 13 shows an example in which two circular heating ports are provided on the top plate 9, and induction heating coil 130a is applied to one of the two heating ports and induction heating coil 130b is applied to the other heating port, but the number of heating ports is not limited to the example shown in Fig. 13.

[0049] The inverter board 7 has a rectifier circuit (not shown) that converts AC power to DC, and an inverter circuit (not shown) that generates a high-frequency current from the DC and supplies it to the induction heating coils 130a and 130b. The inverter circuit is composed of an electric circuit such as a half-bridge inverter, a full-bridge inverter, or a single-transistor voltage resonance inverter. The operation unit 10 is for a user to adjust the heat and the like, and is, for example, a static switch type input device. The arrangement and structure of the operation unit 10 are not limited to the example shown in FIG. 13, and may be a dial type or a tact switch type. The display unit 11 notifies the user of the heat and the elapsed heating time, and is, for example, a liquid crystal display. The arrangement and structure of the display unit 11 are not limited to the example shown in FIG. 13, and may be other configurations, for example, a 7-segment LED (Light Emitting Diode).

[0050] The induction heating coils 130a and 130b correspond to any one of the induction heating coils 100, 110, and 120 described in embodiment 1. The induction heating coils 130a and 130b are connected to an inverter board 7, and are supplied with high-frequency current from the inverter board 7 to induction heat the object 6 to be heated placed on the top plate 9.

[0051] According to the second embodiment, the side wall portion 4c of the coil base 4 is provided between the conductors adjacent in the radial direction of the coil part 1. Since the side wall portion 4c forming a groove portion for accommodating the conductor is provided between the conductors in the radial direction, insulation between the conductors is ensured. Therefore, it is possible to suppress the conductors adjacent in the radial direction from coming into contact with each other and short-circuiting due to the deformation of the induction heating coil. In addition, when the material of the coil base 4 is resin, the coil part 1 comes into contact with the resin, and a high heat-resistant resin can be applied to the material of the coil base 4 according to the temperature of the coil part 1. Therefore, for example, compared with an induction heating coil formed of a printed wiring board using a resin such as glass epoxy having a low heat-resistant temperature, the coil part 1 can be used in a higher temperature state. As a result, the cooling structure of the induction heating coils 130a and 130b can be simplified. For example, the cooling fan (not shown) for cooling the induction heating coils 130a and 130b can be made smaller.

[0052] Furthermore, although embodiments of the induction heating coil and induction heating cooker of the present disclosure have been described, the present disclosure is not limited to the above-described embodiments, and various modifications or combinations are possible without departing from the spirit and scope of the present disclosure.

[0053] Various aspects of the induction heating coil and induction heating cooker of the present disclosure will be described below as an appendix.

[0054] (Appendix 1) An induction heating coil for heating an object to be heated, A coil portion in which a conductor is wound in a spiral shape; a coil base having a plurality of grooves formed at intervals in a radial direction of the coil portion, the conductors being housed in the grooves, and a side wall portion forming the grooves keeps a constant distance between the conductors in the radial direction; An induction heating coil comprising: (Appendix 2) The coil base has a through portion in at least a part of the groove portion, the through portion having no bottom surface portion. 2. An induction heating coil as described in claim 1. (Appendix 3) the coil base has a plurality of protrusions provided on a bottom surface of the groove to prevent the conductor of the coil portion from contacting the bottom surface, The coil portion is supported by the plurality of protrusions. 3. An induction heating coil according to claim 1 or 2. (Appendix 4) The coil portion is composed of the spiral-shaped metal plate. 2. An induction heating coil as described in claim 1. (Appendix 5) The coil portion includes: A first conductor, which is the conductor disposed on the inner periphery side; a second conductor that is the conductor disposed on an outer periphery side of the first conductor; A conductor width, which is a length in the radial direction of the second conductor, is wider than the conductor width of the first conductor. 5. An induction heating coil as described in claim 4. (Appendix 6) The metal plate is aluminum or an aluminum alloy. 5. An induction heating coil as described in claim 4. (Appendix 7) The plate thickness of the conductor of the coil portion is 1.2 mm or more and 3.0 mm or less. 7. The induction heating coil of claim 6. (Appendix 8) The coil portion has a terminal portion at an end portion thereof, the terminal portion having a screw hole formed therein, The terminal portion is integral with the spiral-shaped conductor. 8. An induction heating coil according to claim 6 or 7. (Appendix 9) A cylindrical protrusion is provided on the periphery of the screw hole. 9. The induction heating coil of claim 8. (Appendix 10) The protrusion is formed on a surface of the coil portion facing the object to be heated, In the terminal portion, a surface on which the protrusion is not formed has a flat shape. 10. The induction heating coil of claim 9. (Appendix 11) At least the surface of the terminal portion of the coil portion is coated with a corrosion-resistant metal, The terminal portion is connected to a lead wire having a connection terminal made of copper. 9. The induction heating coil of claim 8. (Appendix 12) The terminal portion is connected to a copper lead wire having a connection terminal whose surface is coated with aluminum. 9. The induction heating coil of claim 8. (Appendix 13) The terminal portion is bent in a vertical direction with respect to a surface facing the object to be heated. 13. An induction heating coil according to any one of claims 8, 9, 11 and 12. (Appendix 14) The coil portion has a plurality of through holes provided in the conductor, The coil portion is fixed to the coil base by screws passing through each of the plurality of through holes. 5. An induction heating coil as described in claim 4. (Appendix 15) In the coil portion, a conductor width, which is a length in the radial direction of the conductor in a portion where the through hole is provided, is wider than the conductor width in a portion where the through hole is not provided. 15. The induction heating coil of claim 14. (Appendix 16) the coil base has a plurality of protrusions on a bottom surface of the groove, The coil portion has a plurality of through holes provided in the conductor, The coil portion is disposed so that the protrusion portion passes through the through hole. 5. An induction heating coil as described in claim 4. (Appendix 17) In the coil portion, a conductor width, which is a length in the radial direction of the conductor in a portion where the through hole is provided, is wider than the conductor width in a portion where the through hole is not provided. 17. The induction heating coil of claim 16. (Appendix 18) The protrusion has a detachment prevention portion at a tip end thereof for preventing the coil portion from detaching from the coil base. 18. The induction heating coil according to claim 16 or 17. (Appendix 19) An induction heating cooker comprising the induction heating coil according to any one of appendixes 1 to 18. [Explanation of symbols]

[0055] 1 coil portion, 1a first terminal portion, 1b second terminal portion, 1c protrusion portion, 1d through hole, 1e to 1h conductor, 2 antimagnetic ring, 3 magnetic body, 4 coil base, 4a conductor accommodating groove portion, 4b magnetic body accommodating groove portion, 4c side wall portion, 4d conductor holding portion, 4f protrusion portion, 4g positioning pin, 4h conductor fixing portion, 5 screw, 6 object to be heated, 7 inverter board, 8 housing, 9 top plate, 10 operation portion, 11 display portion, 100, 110, 120, 130a, 130b induction heating coil, 200 induction heating cooker.

Claims

1. An induction heating coil for heating an object to be heated, A coil portion in which a conductor is wound in a spiral shape; a coil base having a plurality of grooves formed at intervals in a radial direction of the coil portion, the conductors being housed in the grooves, and a side wall portion forming the grooves keeps a constant distance between the conductors in the radial direction; An induction heating coil comprising:

2. The coil base has a through portion in at least a part of the groove portion, the through portion having no bottom surface portion.

2. The induction heating coil according to claim 1.

3. the coil base has a plurality of protrusions provided on a bottom surface of the groove to prevent the conductor of the coil portion from contacting the bottom surface, The coil portion is supported by the plurality of protrusions.

2. The induction heating coil according to claim 1.

4. The coil portion is composed of the spiral-shaped metal plate.

2. The induction heating coil according to claim 1.

5. The coil portion includes: A first conductor, which is the conductor disposed on the inner circumferential side; a second conductor that is the conductor disposed on an outer periphery side of the first conductor; A conductor width, which is a length in the radial direction of the second conductor, is wider than the conductor width of the first conductor.

5. The induction heating coil according to claim 4.

6. The metal plate is aluminum or an aluminum alloy.

5. The induction heating coil according to claim 4.

7. The plate thickness of the conductor of the coil portion is 1.2 mm or more and 3.0 mm or less.

7. The induction heating coil according to claim 6.

8. The coil portion has a terminal portion at an end portion thereof, the terminal portion having a screw hole formed therein, The terminal portion is integral with the spiral-shaped conductor.

7. The induction heating coil according to claim 6.

9. A cylindrical protrusion is provided on the periphery of the screw hole.

9. The induction heating coil according to claim 8.

10. The protrusion is formed on a surface of the coil portion facing the object to be heated, In the terminal portion, a surface on which the protrusion is not formed has a flat shape.

10. The induction heating coil according to claim 9.

11. At least the surface of the terminal portion of the coil portion is coated with a corrosion-resistant metal, The terminal portion is connected to a lead wire having a connection terminal made of copper.

9. The induction heating coil according to claim 8.

12. The terminal portion is connected to a copper lead wire having a connection terminal whose surface is coated with aluminum.

9. The induction heating coil according to claim 8.

13. The terminal portion is bent in a vertical direction with respect to a surface facing the object to be heated.

9. The induction heating coil according to claim 8.

14. The coil portion has a plurality of through holes provided in the conductor, The coil portion is fixed to the coil base by screws passing through each of the plurality of through holes.

5. The induction heating coil according to claim 4.

15. In the coil portion, a conductor width, which is a length in the radial direction of the conductor in a portion where the through hole is provided, is wider than the conductor width in a portion where the through hole is not provided.

15. The induction heating coil of claim 14.

16. the coil base has a plurality of protrusions on a bottom surface of the groove, The coil portion has a plurality of through holes provided in the conductor, The coil portion is disposed so that the protrusion portion passes through the through hole.

5. The induction heating coil according to claim 4.

17. In the coil portion, a conductor width, which is a length in the radial direction of the conductor in a portion where the through hole is provided, is wider than the conductor width in a portion where the through hole is not provided.

17. The induction heating coil of claim 16.

18. The protrusion has a detachment prevention portion at a tip end thereof for preventing the coil portion from detaching from the coil base.

17. The induction heating coil of claim 16.

19. An induction heating cooker comprising the induction heating coil according to any one of claims 1 to 18.

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