JP6446288B2 - Induction heating device - Google Patents

Description

  The present invention relates to an induction heating apparatus suitable for induction heating of cooking utensils such as a pan.

  The induction heating device is a heating cooker of an electromagnetic induction heating (IH) method using electromagnetic induction by a coil. In recent years, induction heating devices have been growing in demand as cooking utensils for home use because they do not pollute the air because they do not emit flames, and the surface on which the pan is placed (top plate) is flat and easy to clean. Yes.

  As a background art of the present invention, for example, there is one described in Patent Document 1.

  In Patent Document 1, as a problem, in the case where the shield member is fixed to the lower surface of the coil base, the distance between the induction heating coil supported by the coil base and the shield member is small, and the effect of reducing the leakage magnetic field is Although the heat generation of the shield member is large, the induction heating coil, which is a heating element, is basically covered with the shield member, so the exposed portion of the induction heating coil (the portion exposed to the cooling air) There is a problem that the cooling performance of the induction heating coil is reduced and the cooling performance of the induction heating coil is lowered.

  With respect to such a problem, in Patent Document 1, “the induction heating cooker of the present invention is at least an induction heating coil, a ferrite core that is disposed below the induction heating coil and serves as a magnetic path of magnetic flux generated from the induction heating coil, and A coil unit having a coil base for supporting an induction heating coil and a ferrite core, a shield member provided below the coil unit for reducing a leakage magnetic field from the induction heating coil, and cooling air for cooling the coil unit are ejected. And a jet plate disposed below the shield member, the shield member having a plurality of second holes corresponding to the plurality of first holes of the jet plate And the second hole is fixed to the upper surface of the jet plate so as to coincide with the first hole of the jet plate. It is.

  Moreover, although it is a rice cooker, patent document 2 describes what arrange | positioned the integral shield member from the lower surface to the side surface.

JP 2013-54847 A Japanese Patent Laid-Open No. 7-246156

  However, since the induction heating cooker described in Patent Document 1 uses a jet plate, the cost may increase due to material costs, processing costs, and the like.

  In addition, since the leakage magnetic flux does not contribute to heating, the generation of the leakage magnetic flux not only lowers the heating efficiency but also causes noise to the circuit and may cause malfunction.

  Further, the saturation magnetic flux density of the magnetic material disposed under the heating coil decreases with an increase in temperature, and there is a possibility that a large current flows through the coil without performing the function as the magnetic material.

  According to the rice cooker of Patent Document 2 in which the integral shield member is arranged from the lower surface to the side surface, the heat generated in the shield member spreads over the entire shield member. As a result, the magnetic body (ferrite core) supported by the shield member is heated, and, as in Patent Document 1, “the saturation magnetic flux density of the magnetic body disposed under the heating coil decreases as the temperature rises. This causes a problem that a large current may flow through the coil without performing its function.

  Accordingly, an object of the present invention is to provide an induction heating cooker that can reduce the leakage magnetic flux and reduce the thickness of the magnetic flux at low cost, and can reduce the temperature rise of the magnetic material.

  In order to solve the above-described problems, an induction heating apparatus of the present invention includes a heating coil, a magnetic body that is installed below the heating coil and forms a magnetic path of magnetic flux generated from the heating coil, and a magnetic body that is provided below the magnetic body. An induction heating apparatus having a shield for supporting a body, wherein the shield includes a shield plate disposed below the heating coil, and a shield ring disposed around the heating coil, and the shield plate is in space with the shield ring. It is characterized by being arranged separately.

  ADVANTAGE OF THE INVENTION According to this invention, the induction heating apparatus which can implement | achieve thickness reduction, reduction of leakage magnetic flux, and temperature rise reduction of a magnetic body at low cost can be provided.

FIG. 3 is an isometric view of the pedestal portion 101 of the induction heating device according to the first embodiment. 1 is a schematic configuration diagram showing an overall configuration of an induction heating apparatus 100 in Embodiment 1. FIG. FIG. 6 is an isometric view of the pedestal portion 101 of the induction heating device according to the first modification of the first embodiment. FIG. 10 is an isometric view of the pedestal portion 101 of the induction heating device according to the second modification of the first embodiment. The figure which shows the whole structure of the heating coil of the induction heating apparatus which concerns on the 3rd modification of Example 1. FIG. The figure which shows the structure of the shield 80 of the induction heating apparatus which concerns on the 4th modification of Example 1. FIG. The figure which shows the structure of the shield 80 of the induction heating apparatus which concerns on the 5th modification of Example 1. FIG. FIG. 6 is an isometric view of the pedestal portion 101 of the induction heating device according to the second embodiment. The figure which shows the structure of the shield 80 of the induction heating apparatus which concerns on the 1st modification of Example 2. FIG. FIG. 10 is an isometric view of the pedestal portion 101 of the induction heating device according to the third embodiment. The figure which shows the length of the overhang | projection part of the shield ring 80d of Example 3, and an induced voltage. The figure which shows the structure of the shield 80 of the induction heating apparatus which concerns on the 1st modification of Example 3. FIG.

  Hereinafter, the induction heating device of the present invention will be described based on the illustrated embodiments. In each embodiment described below, the same reference numerals are given to the same components.

  The first embodiment will be described with reference to FIGS. 1 to 7. First, FIG. 2 is a schematic configuration diagram showing the overall configuration of the induction heating apparatus 100 in the first embodiment.

  The induction heating device 100 includes a power supply circuit 20, a control circuit 9, and a pedestal portion 101. The induction heating device 100 is also called an IH cooking heater, and induction-heats the pan 10 placed on the pedestal portion 101.

  Of these, the pedestal portion 101 is configured by sequentially arranging a shield 80, a magnetic body 70, a heating coil 50, and a top plate 60 from the bottom surface side. On the top plate 60 on the upper surface, the pan 10 which is a cooking utensil to be heated is placed and heated. In many cases, the pedestal portion has a circular shape including an ellipse when viewed from above.

  More specifically, the pedestal portion will be described. The heating coil 50 is a coil for induction heating using, for example, a litz wire. The top plate 60 is a plate on which the pan 10 is placed, is made of heat-resistant glass having a small magnetic loss, and covers the upper surface of the heating coil 50. The magnetic body 70 is made of, for example, ferrite having a high magnetic permeability, and is provided on the lower surface of the heating coil 50. The shield 80 is made of a conductor such as metal aluminum, copper, or iron, for example, and is provided on the lower surface of the magnetic body 70. The shield 80 blocks magnetic flux generated from the heating coil 50 and supports the magnetic body 70 and the heating coil 50.

  The power supply circuit 20 includes a rectifier circuit 2, an inverter 3, and a resonance circuit 4. The power supply circuit 20 is supplied with electric power from the power supply 1 having a commercial frequency, and the heating coil 50 is driven by this electric power. The rectifier circuit 2 rectifies the input alternating current and outputs direct current. The rectifier circuit 2 is a bridge circuit configured to include, for example, a diode. The inverter 3 is a resonant inverter that outputs a high-frequency alternating current. The inverter 3 includes a semiconductor switch such as a MOS (Metal Oxide Semiconductor) transistor or IGBT (Insulated-Gate Bipolar Transistor), and a driver for driving these semiconductor switches. The resonance circuit 4 is a circuit that resonates with the heating coil 50. The resonance circuit 4 includes a capacitor. Moreover, it has a heat sink that cools the semiconductor switch, and the shield plate is also used as the heat sink.

  The control circuit 9 performs on / off of each semiconductor switch of the power supply circuit 20, voltage / current detection of each part, adjustment of the frequency of the inverter 3, and the like.

  FIG. 1 is an isometric view of a pedestal portion 101 of the induction heating apparatus according to the first embodiment. Here, for the sake of explanation, a 1/8 model of the pedestal portion 101 (comprising the heating coil 50, the ferrite 70, the shield 80, and the top plate 60) of the induction heating apparatus 100 is illustrated. According to FIG. 1 of the 1/8 model, the left A point side is the center side of the pedestal portion 101 having a circular shape from the upper surface, and the right B point side is the peripheral side of the circular pedestal portion 101. .

  Here, the heating coil 50 is a coil for induction heating, and includes a coil 50a (first coil) and a coil 50b (second coil). At least two sets of the strip-shaped coil 50a (first coil) and the coil 50b (second coil) are arranged in a donut shape concentrically from the pedestal portion center side A. In this case, the coil 50b has an inner diameter larger than the outer diameter of the coil 50a.

  The magnetic body 70 is arranged radially from the center of the heating coil 50 under the heating coil 50, and is arranged so as to straddle the concentric belt-like coils 50a and 50b. Since FIG. 1 is a 1/8 model, eight radial magnetic bodies 70 are arranged radially from the center side of the heating coil 50. The saturation flux density of the magnetic body 70 decreases as the temperature rises, and when the magnetic flux density of the magnetic body 70 is equal to or higher than the saturation flux density, the magnetic flux does not flow and the loss may increase.

  In the present invention, the shield 80 is composed of a shield ring 80a and a shield plate 80b formed of a conductor such as aluminum, which are separated from each other. Among these, the shield ring 80a is larger than the outer diameter of the outer coil 50b, and is disposed on the outer periphery of the coil 50b. The shield plate 80b supports the magnetic body 70 from the bottom side, and a heat-resistant silicon adhesive, a heat-resistant insulating tape, a resin, or the like is used for the support. In the present invention, the lower portion and the peripheral portion of the coil 50 are not covered with an integral shield, but the lower portion and the peripheral portion are separate shields, and a space S (distance L2) is provided therebetween.

  Moreover, in Example 1 of this invention, the opening part 90 is provided in the appropriate location of the base part 101. FIG. The first opening 90a is formed between the shield ring 80a and the shield plate 80b, and is a distance L1 that maintains insulation between the inner diameter of the shield ring 80a at the outer peripheral portion and the outer diameter of the shield plate 80b. The second opening 90 b is provided in the bottom shield plate 80 b and is located below the magnetic body 70. The third opening 90c is a hole that is provided at a position corresponding to the center of the heating coil 50 and through which a lead wire or the like of the coil 50a passes. In the case of the present invention, the space and the opening are used in terms of terms. The space is an opening formed between the shield ring 80a and the shield plate 80b, but is distinguished from other openings by being referred to as a space.

  According to the present invention, since the shield ring 80a and the shield plate 80b are separated, heat generation of the shield plate 80b supporting the magnetic body 70 can be suppressed, and the temperature rise of the magnetic body 70 can be reduced. That is, the cooling due to the opening of the lower part of the magnetic body 70 and the lowering of the heat of the lower shield plate 80b are combined to make it difficult for the shield plate 80b to be heated and supported by the shield plate 80b. Heating of the magnetic body 70 is suppressed as much as possible. By suppressing the heating of the magnetic body 70, a decrease in the saturation magnetic flux density can be suppressed.

  The above-described effects according to the present invention are obtained by separating the shield ring 80a and the shield plate 80b, and are also enjoyed in the following embodiments having this structure and modifications thereof.

  Further, according to the above arrangement of the first embodiment, the induction voltage at a position 20 mm below the shield plate 80b on the bottom side is reduced by about 60% compared with the induction heating apparatus using only the shield ring 80a as a shield as a result of electromagnetic field analysis. It became. The heat generated by the shield was 90% of the heat generated by the shield ring 80a at the outer peripheral portion and 10% of the shield plate 80b on the bottom side of the heat generated by all the shields.

  Further, the magnetic bodies 70 arranged radially are positioned above the opening 90b of the shield plate 80b, so that the magnetic bodies 70 are not obstructed by the shield material and are advantageous for cooling, and the magnetic bodies 70 are saturated. A decrease in magnetic flux density can be prevented.

  Further, since the magnetic flux mainly passes through the magnetic body 70, the leakage magnetic field can be reduced even if the opening 90b is provided.

  FIG. 3 is an isometric view of the pedestal portion 101 of the induction heating apparatus according to the first modification of the first embodiment. As is apparent from the comparison with FIG. 1, the opening 90b is not provided in the shield plate 80b below the magnetic body 70, but the shield plate 80b is disposed only on the inner peripheral side, and the magnetic body 70 is shielded on the inner peripheral side. The space 80 (distance L2) is provided between the outer peripheral shield ring 80a and the inner peripheral shield plate 80b.

  3 adopts substantially the same configuration as FIG. 1 in other parts. That is, in FIG. 3, the heating coil 50 is a coil for induction heating, and includes a coil 50a (first coil) and a coil 50b (second coil). The coil 50b has an inner diameter larger than the outer diameter of the coil 50a. The magnetic body 70 is radially arranged around the central axis of the heating coil 50 under the heating coil 50, and is arranged so as to straddle the coils 50a and 50b. The shield 80 includes a shield ring 80a and a shield plate 80b separated by a conductor such as aluminum. The shield ring 80a is larger than the outer diameter of the coil 50b and is disposed on the outer periphery of the coil 50b.

  What is characteristic in FIG. 3 is the shield plate 80b. The shield plate 80b has an outer diameter smaller than the inner diameter of the coil 50b and shields the magnetic flux generated mainly by the coil 50a. In this configuration, since the shield plate 80b is not disposed below the coil 50b, an air flow path can be secured, which is advantageous for cooling the coil 50b and the magnetic body 70. The induced voltage is reduced by about 25% compared to the shield ring 80a alone.

  FIG. 4 is an isometric view of the pedestal portion 101 of the induction heating apparatus according to the second modification of the first embodiment. As apparent from the comparison with FIG. 1, the opening 90 b is not provided in the shield plate 80 b below the magnetic body 70, but the shield 70 b is disposed only on the outer peripheral side to support the magnetic body 70 on the outer peripheral side, A space S <b> 1 is secured in the lower part on the inner peripheral side of the magnetic body 70.

  4 adopts substantially the same configuration as FIG. 1 in other parts. That is, in FIG. 4, the heating coil 50 is a coil for induction heating, and includes a coil 50a (first coil) and a coil 50b (second coil). The coil 50b has an inner diameter larger than the outer diameter of the coil 50a. The magnetic body 70 is radially arranged around the central axis of the heating coil 50 under the heating coil 50, and is arranged so as to straddle the coils 50a and 50b. The shield 80 includes a shield ring 80a and a shield plate 80b separated by a conductor such as aluminum. The shield ring 80a is larger than the outer diameter of the coil 50b and is disposed on the outer periphery of the coil 50b.

  What is characteristic in FIG. 4 is the shield plate 80b. The shield plate 80b has an outer diameter smaller than the inner diameter of the shield ring 80a and shields the magnetic flux generated mainly by the coil 50b. As a result, since the coil 50a and the magnetic body 70 are not disposed below the coil 50a, it is advantageous for cooling the coil 50a and a space for installing a sensor or the like can be secured near the center of the heating coil 50. The induced voltage is reduced by about 73% compared to the shield ring 80a alone.

  FIG. 5 is a diagram illustrating an overall configuration of a heating coil of an induction heating device according to a third modification of the first embodiment. In the first embodiment, the heating coil 50 is circular and includes the coil 50a and the coil 50b, but is not limited thereto. In the case of FIG. 5, the heating coil 50 is an induction heating coil and has an elliptical shape, and an opening 90C is formed at the center.

  FIG. 5 shows only the feature that the heating coil is elliptical, and the other features of the first embodiment are adopted as they are. For example, although the positional relationship of partially supporting the radial magnetic body 70 with the shield plate 80b is not illustrated, this portion is as illustrated in the other embodiments.

  In FIG. 5, the shield 80 includes a shield ring 80a and a shield plate 80b separated by a conductor such as aluminum. The shield ring 80a is larger than the outer diameter of the heating coil 50. For example, the shield ring 80a is disposed on the outer periphery maintaining a certain distance L1 from the outer diameter of the heating coil 50 through the opening 90a. The shield plate 80b on the bottom side is arranged with an outer diameter smaller than the inner diameter of the shield ring 80a and with a certain insulation distance from the inner diameter of the shield ring 80a. With the above configuration, the leakage magnetic field can be reduced with respect to various coil shapes.

  FIG. 6 is a diagram illustrating a configuration of the shield 80 of the induction heating apparatus 100 according to the fourth modification of the first embodiment. The example of arrangement | positioning of the opening part 90b provided in the shield plate 80b of the bottom part concerning Example 1 of FIG. 1 is shown. In the illustration of FIG. 6, the coil 50 is not shown, and only the shield 80 is displayed. Therefore, the space S and the distance L2 between the shield plate 80b and the shield ring 80a are not the opening 90a. Show. In FIG. 6, the opening at the center is described as 90C for convenience.

  The fourth modification of the first embodiment is in the arrangement of the opening 90b provided in the shield plate 80b. In FIG. 6, two types of openings 90b are provided. The opening 90b1 is disposed below the magnetic body corresponding to the opening 90b in FIG. 1 and contributes to improving the cooling performance of the magnetic body 70. Since the opening 90b2 is provided on the shield plate 80b located below the heating coil 50, it contributes to improving the cooling performance of the heating coil 50. The induced voltage is reduced by about 40% compared to the shield ring 80a alone.

  According to the above configuration, the magnetic body 70 is cooled by the opening 90b1 and the heating coil 50 is cooled by the opening 90b2, and the leakage magnetic field can be effectively reduced.

  FIG. 7 is a diagram illustrating a configuration of the shield 80 of the induction heating apparatus 100 according to the fifth modification of the first embodiment. The structure of the shield plate 80b of the bottom part which concerns on Example 1 of FIG. 1 is shown.

  1 includes a shield ring 80a and a shield plate 80b separated by a conductor such as aluminum. The shield ring 80 a is larger than the outer diameter of the heating coil 50, for example, is disposed on the outer periphery maintaining a certain distance from the outer diameter of the heating coil 50. In FIG. 1, the shield plate 80b is formed of a single flat donut-shaped plate.

  On the other hand, the bottom shield plate 80b, which is the feature of FIG. 7, has an outer diameter smaller than the inner diameter of the shield ring 80a, and is arranged with a certain insulation distance from the inner diameter of the shield ring 80a. In addition, a slit portion 80b1 is provided on the outer peripheral side of the shield plate 80b on the radiation toward the coil center. By increasing the surface area of the shield plate 80b, the heat dissipation of the shield plate 80b is improved. The induced voltage is reduced by about 30% compared to the shield ring 80a alone.

  With the above configuration, the heat dissipation of the shield that generates heat can be improved and the leakage magnetic field can be reduced.

  A second embodiment of the present invention will be described with reference to FIGS. In the first embodiment, the shield plate 80b is formed by a single flat donut-shaped plate. However, in the second embodiment, an example of the induction heating apparatus 100 configured by multiplexing the shield plates 80b in a donut shape will be described. . In addition, description of the structure and function which were illustrated and demonstrated in 1st Embodiment among the induction heating apparatuses 100 of 2nd Embodiment is abbreviate | omitted.

  FIG. 8 is an isometric view of a 1/8 model showing the shield 80 in the second embodiment configured to include the shield plate 80b multiplexed with the shield ring 80a.

  In FIG. 8, the shield 80 includes a shield ring 80a, a shield plate 80b, and a shield plate 80c separated by a conductor such as aluminum. The shield ring 80 a is larger than the outer diameter of the heating coil 50, for example, is disposed on the outer periphery maintaining a certain distance from the outer diameter of the heating coil 50.

  Of the two shield plates 80 arranged in a donut shape, the outer shield plate 80b mainly contributes to the reduction of the leakage magnetic field generated in the coil 50b, is located inside the shield ring 80a, and between the shield ring 80a. An opening 90 a is provided to support the magnetic body 70. For the support, a material such as a heat-resistant silicone adhesive or a heat-resistant insulating tape is used.

  Of the two shield plates 80 arranged in a donut shape, the inner shield plate 80c mainly contributes to reducing the leakage magnetic field generated in the coil 50c, and the outer diameter is equal to or smaller than the inner diameter of the shield plate 80b. An opening 90c is provided. Also, an opening 90d is formed between the outer shield plate 80b. Depending on the size of the magnetic body 70, the magnetic body 70 may be supported by the shield plate 80c.

  In addition, with respect to the opening 90 formed by this configuration, the opening 90a is a region between the shield ring 80a and the outer diameter of the shield plate 80b, and is set to be equal to or longer than a distance that can ensure insulation between the shield ring 80a and the shield plate 80b. .

  The opening 90d newly formed in the second embodiment is an area between the inner diameter of the shield plate 80b and the outer diameter of the shield plate 80c, and has a shorter distance than the longitudinal direction under the magnetic body 70, and is heated. This is advantageous for cooling the coils 50 a and 50 b and the magnetic body 70.

  The opening 90c on the center side is provided in a region corresponding to the center of the coil 50, and is an opening of a shield plate 80c for passing a sensor, a cable, or the like. The induced voltage is reduced by about 84% compared to the induced voltage of only the shield ring 80a.

  With the above configuration, the leakage magnetic field can be reduced by using a plurality of shield plates having a donut-like structure that is advantageous for cooling the heating coil 50 and the magnetic body 70.

  FIG. 9 is a diagram illustrating a shield configuration of the induction heating apparatus 100 according to the first modification of the second embodiment. Here, the shield 80 includes a shield ring 80a separated by a conductor such as aluminum, a shield plate 80b, and a shield plate 80c.

  The shield ring 80 a is larger than the outer diameter of the heating coil 50, for example, is disposed on the outer periphery maintaining a certain distance from the outer diameter of the heating coil 50.

  The donut-shaped large-diameter shield plate 80b is connected to the donut-shaped small-diameter shield plate 80c by a connecting portion 81 that is a conductor. In the connection part 81, the current of the shield plate 80b and the shield plate 80c is concentrated, so that the magnetic flux density near the connection part 81 is increased, and the magnetic flux density is reduced except for the vicinity of the connection part 81. When forming the shield plate 80b and the shield plate 80c, the shield plate 80b and the shield plate 80c may be formed integrally at the beginning and punched out at a portion corresponding to the opening 90d.

  In the case of the induction heating apparatus 100 according to the first modification of the second embodiment of FIG. 9, the induction voltage is reduced by about 80% at the lower portion of the connection portion 81 (in the direction of 3 o'clock) in comparison with the shield ring 80a alone, It is reduced by about 85% at the bottom of the region 82 (6 o'clock direction).

  With the above configuration, by connecting the shields at locations other than the location where the leakage magnetic field should be reduced, the leakage magnetic field at the location where the leakage magnetic field should be reduced can be reduced.

  The third embodiment will be described with reference to FIGS. 10 to 12. First, FIG. 10 is an isometric view of the pedestal portion 101 of the induction heating apparatus in the third embodiment.

  Also in the third embodiment, the shield 80 employs a configuration in which the shield plate 80C and the shield ring 80d are separated, but the shield ring 80d is configured by a peripheral portion and a bottom portion connected to the peripheral portion. In addition, description of the structure and function which were illustrated and demonstrated in the said Example among the induction heating apparatuses 100 of Example 3 is abbreviate | omitted.

  In FIG. 10, a heating coil 50 is a coil for induction heating, and includes a coil 50a (first coil) and a coil 50b (second coil). The coil 50b has an inner diameter larger than the outer diameter of the coil 50a. The magnetic body 70 is radially disposed around the central axis of the heating coil 50 under the heating coil 50, is disposed so as to straddle the coils 50a and 50b, and is supported by the shield ring 80d.

  The shield 80 includes a shield plate 80C and a shield ring 80d. The shield ring 80d is a conductor such as aluminum, and the outer diameter of the shield 80d is larger than the outer diameter of the heating coil 50, and is arranged on the outer periphery with a certain distance from the outer diameter of the heating coil 50. The cross section of the shield ring 80d in the third embodiment is L-shaped, and an overhang is provided in the center direction of the heating coil 50 from the lower surface of the shield ring 80d.

  The shield plate 80C is located in the vicinity of the coil 50a (first coil), and is separated from the shield ring 80d to form a space S (distance L2). This space S has an inner diameter corresponding to the projecting portion of the shield 80d, which is advantageous for cooling the heating coil 50 and the magnetic body 70, and the central opening 90C is a space for sensor installation or the like.

  FIG. 11 is a diagram illustrating the length (horizontal axis) and the induced voltage (vertical axis) of the projecting portion of the shield ring 80d according to the third embodiment. The case where there is no overhanging portion, that is, only the shield ring 80C having only the above-mentioned peripheral edge portion, is the induced voltage (vertical axis) 100%. The induced voltage decreases as the overhanging portion becomes longer, and when it exceeds half the inner diameter of the heating coil 50b, the induced voltage is reduced by about 40%.

  With the above configuration, the magnetic body 70 is supported by the shield ring 80d, which is advantageous for cooling. In addition, the length of the overhanging portion can be changed to reduce the leakage magnetic field.

  FIG. 12 is a diagram illustrating a shield configuration of the induction heating apparatus 100 according to the first modification of the third embodiment. According to FIG. 12, a shield 80C, a space S, and a shield ring 80d having a bottom portion are sequentially arranged from the central opening 90C to the peripheral edge side. Also, a part of the bottom of the shield ring 80d has openings 90e at predetermined intervals near the periphery.

  Of the shields 80 made of a conductor such as aluminum, the inner shield 80c is smaller than the inner diameter of the shield 80d and has an opening 90c in the center.

  The outer diameter of the shield 80d is larger than the outer diameter of the heating coil 50, and the shield 80d is disposed on the outer periphery maintaining a certain distance from the outer diameter of the heating coil 50. The cross section of the shield 80d is L-shaped, and an overhang is provided in the center direction of the heating coil 50 from the lower surface of the shield 80d.

  The magnetic body 70 is radially arranged around the central axis of the heating coil 50 under the heating coil 50, is disposed so as to straddle the coils 50a and 50b, and is supported by the lead portion of the shield 80d and the shield 80c.

  The opening 90e may be provided in the projecting portion of the shield ring 80d, and may be used for cooling the coil 50b and the magnetic body 70, and may pass through the lead wire of the coil 50b. The space S is located below the magnetic body 70 between the inner diameter corresponding to the projecting portion of the shield ring 80d and the outer diameter of the shield 80c, and is advantageous for cooling the heating coil 50 and the magnetic body 70. The opening 90c is an opening of a shield plate 80c through which a sensor, a cable and the like provided in a region corresponding to the center of the coil 50 are passed.

  Although the embodiments have been described above, the following modifications can be made. For example, although the outer diameter of the shield plate 80b is smaller than the inner diameter of the shield ring 80a, the present invention is not limited to this. By arranging the shield plate 80b below the shield ring 80a and making it larger than the inner diameter of the shield ring 80a, the leakage magnetic field can be further reduced.

  Moreover, although the shield plates 80b and 80c are plate-shaped, this is not restrictive. For example, it may be changed according to the shape of a metal body or coil having a cooling fin structure, or may be changed to a shape that takes into account sensor space, leader line, and the like. Moreover, you may use also as the heat sink used for cooling of a switching element etc.

  The opening 90 means that there is no conductive shield member in the opening. That is, even if it is filled with a nonmetallic body, it is an opening.

1: Power supply 2: Rectifier circuit 3: Inverter 4: Resonant circuit 9: Control circuit 10: Pot (cooking utensil)
20: Power supply circuit 50: Heating coil 50a: Coil (first coil)
50b: Coil (second coil)
60: top plate 70: magnetic body 80: shield 80a, 80d: shield ring 80b, 80c: shield plates 90, 90a, 90b, 90c: opening 100: induction heating device 101: pedestal portion S: space L1, L2: distance

Claims (14)

A heating coil having a circular or elliptical belt shape, in which the inner heating coil is arranged inside the outer heating coil , and a center of the circular or elliptical heating coil below the heating coil An induction heating apparatus having a magnetic body that is installed in an outer peripheral direction from a portion and forms a magnetic path of a magnetic flux generated from the heating coil, and a shield that is provided below the magnetic body and supports the magnetic body,
The shield includes a shield plate disposed below the heating coil and a shield ring disposed around the heating coil, and the shield plate has an outer diameter shorter than an inner diameter of the shield ring , An induction heating apparatus characterized in that an outer diameter of the plate and an inner diameter of the shield ring are spatially separated from each other. The induction heating device according to claim 1 ,
An induction heating apparatus having a first opening between the heating coil and the shield ring. The induction heating apparatus according to claim 1 or 2 ,
Induction heating apparatus characterized by having the magnetic body said shield plate disposed under the second opening in the lower position of the magnetic body. The induction heating device according to any one of claims 1 to 3 ,
The induction heating apparatus, wherein the shield plate has a third opening on the center side. The induction heating device according to any one of claims 1 to 4 , wherein
The induction heating apparatus, wherein the shield plate is provided in common at a lower position of the external heating coil and the internal heating coil . The induction heating device according to any one of claims 1 to 4 , wherein
The induction heating apparatus, wherein the shield plate is provided at a lower position for each of the external heating coil and the internal heating coil . The induction heating device according to any one of claims 1 to 4 , wherein
The shield plate is provided at a lower position of a part of the heating coil of the heating coil constituted by the external heating coil and the internal heating coil, and the magnetic plate is provided by the shield plate at a lower position of the heating coil. An induction heating apparatus characterized by supporting a body. The induction heating device according to any one of claims 1 to 7 ,
2. The induction heating apparatus according to claim 1, wherein the shield ring is formed in an L shape and includes a portion disposed around the heating coil and a portion disposed below the heating coil. The induction heating device according to claim 8 ,
An induction heating apparatus, wherein a plurality of fourth openings are formed on a peripheral side of a portion of the shield ring disposed below the heating coil. The induction heating device according to claim 2 ,
The induction heating apparatus, wherein the first opening is located directly below the magnetic body, and an opening area of the first opening is smaller than one surface of the magnetic body. The induction heating device according to any one of claims 1 to 10 ,
The said magnetic body is a some magnetic body arrange | positioned radially, The said shield board has an opening part between the said magnetic bodies, The induction heating apparatus characterized by the above-mentioned. The induction heating device according to any one of claims 1 to 10 ,
An induction heating device, wherein slits are provided radially on the shield plate. The induction heating device according to any one of claims 2 to 4 ,
An induction heating apparatus having a sensor, wherein the sensor is arranged in an opening. The induction heating device according to any one of claims 1 to 13 ,
An induction heating apparatus, comprising: a power source for supplying a high frequency to the heating coil; a switching element used for the power source; and a heat sink for cooling the switching element, wherein the shield plate also serves as the heat sink.

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