JP4810779B2 - Induction heating device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an induction heating device used in general households, restaurants, factories and the like.
[0002]
[Prior art]
A heating structure of a conventional induction heating apparatus will be described with reference to FIGS. FIG. 7 is a cross-sectional view of a conventional induction heating cooker, in which 1 is an object to be heated by induction using a high frequency magnetic field generated from a heating coil 2, 2 is a heating coil for induction heating the object to be heated 1, and 3 is a heating coil. Although not particularly shown in the figure, an inverter circuit that supplies a high-frequency current to 2 is connected to the heating coil 2. Reference numeral 4 denotes a plate on which the heated object 1 is placed, and the material thereof is ceramic. 5 is a casing, 6 is a coil base on which the heating coil 2 is placed, 7 is a magnetic body embedded in the coil base 6, and the material is ferrite. The magnetic body 7 is used for the purpose of efficiently supplying a high-frequency magnetic field generated from the heating coil 2 to the article 1 to be heated. Reference numeral 10 denotes a power component that generates a large amount of heat among components constituting the inverter circuit 3, and specifically, an IGBT that is a switching element and a diode bridge. Reference numeral 9 denotes a radiator that radiates heat generated from the power component 10.
[0003]
A cooling device 8 cools the heating coil 2 and the power component 10 by forced air cooling from the side of the heating coil 2 using a sirocco fan or the like. The reason for using the sirocco fan is that it is necessary to ensure sufficient cooling air over the entire surface of the heating coil, and the pressure loss for that is large.
[0004]
The figure which looked at the coil stand 6 from the top is shown in FIG. As shown in FIG. 8, the magnetic body 7 is composed of a plurality of rods, and is arranged radially on the lower surface of the coil base 6.
[0005]
[Problems to be solved by the invention]
However, such a conventional induction heating apparatus has the following problems. That is, as described above, the heating coil is placed on the coil base having the magnetic material disposed on the back surface, and it is difficult to pass the cooling air, and it is also necessary to cool the power components. It is necessary to use a sirocco fan, resulting in an increase in the cost of the product.
[0006]
Against this background, regarding a coil base on which a heating coil is placed in recent years, rod-like magnetic bodies as shown in JP-A-61-71581 are arranged radially from the center of the heating coil, and further inside the coil base made of resin. What is buried is proposed.
[0007]
Even in this configuration, the thickness of the magnetic material is large (in general, about 5 mm in consideration of the saturation magnetic flux density because of the rod-like form), and the sum of the thickness and the resin thickness is the coil. Even if cooling air is blown from the side surface of the heating coil, it is difficult to efficiently cool the lower surface of the heating coil (the upper surface of the heating coil has an object to be heated). There is a plate on which is mounted, and between the heating coil and the plate, at least about 5 mm is necessary for efficient heating in principle of induction heating, and because it is extremely thin, cooling on this surface is also greatly I cannot expect it).
[0008]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described conventional problems, to reduce the necessary cooling of the heating coil and power components with a simple configuration, and to provide an induction heating device that does not require an expensive cooling mechanism such as a sirocco fan. Is.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned conventional problems, the induction heating apparatus of the present invention collects heat generated from the heating coil with a high thermal conductor, and further connects the object to be cooled by connecting to a radiator on which a power component is placed. Concentrate in one place.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 includes a heating coil, an inverter circuit having a switching element and a diode bridge for supplying a high-frequency current to the heating coil, and heat dissipation mounted on at least one of the switching element and the diode bridge. And a high thermal conductor that is provided on the lower surface of the heating coil so as to face the other parts of the inverter circuit through a space and thermally connects the heating coil and the radiator. Since the target is concentrated in one place, it is only necessary to cool the radiator, and as a result, even an inexpensive axial fan can be cooled. In addition, since at least one of the switching element and the diode bridge is connected to a high thermal conductor via a resin ferrite, it is possible to efficiently cool, for example, a component that is difficult to mount on a radiator such as a resonant capacitor. It will be.
[0011]
In the invention according to claim 2, since the heat dissipation effect is enhanced by interposing the resin ferrite between the heating coil and the high thermal conductor, and the magnetic field from the heating coil is confined by the resin ferrite. The material and shape of the conductor can be freely set, and as a result, an inexpensive and simple high thermal conductor can be obtained.
[0012]
The invention described in claim 3 has a configuration in which the resin ferrite is directly connected to the heat radiator, so that a high thermal conductor is not required, and rational cooling is possible with an inexpensive and simple configuration.
[0013]
In the invention according to claim 4 , in particular, since a part or the whole of the back surface of the inverter circuit is covered with resin ferrite, it is possible to more efficiently dissipate heat from the circuit board. It can be realized to be small.
[0014]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
[0015]
(Example 1)
FIG. 1 is a cross-sectional view of an induction heating apparatus according to a first embodiment of the present invention, in which 31 is an object to be heated that is induction-heated, and 32 is spirally wound to generate a high-frequency magnetic field when a high-frequency current flows. A heated heating coil. 33 is an inverter circuit for supplying a high-frequency current to the heating coil 32, 34 is a plate, and the material is ceramic. Reference numeral 35 denotes a casing, and 36 denotes a coil base on which the heating coil 32 is placed, including a magnetic body 37, and the material thereof is PET. The magnetic body 37 has a magnetic permeability of about 1800, and rod-like ferrites are arranged radially. Reference numeral 38 denotes a cooling device configured to cool the radiator 39 intensively. Reference numeral 40 denotes an inverter circuit component, specifically, a switching element 45 and a diode bridge 46.
[0016]
The figure which looked at the heat radiator 39 and the inverter circuit 33 from the top is shown in FIG. The reason why the switching element 45 and the diode bridge 46 are mounted on the radiator is that these two parts are extremely lossy compared to other inverter circuit parts. Specifically, the loss of the switching element 45 is about 50 W, the loss of the diode bridge 46 is about 20 W, and as another inverter circuit component, for example, the loss of the resonance capacitor is about 2 W, and the loss of the choke coil is about 10 W. 41 is a high thermal conductor, and in the case of the present embodiment, a heat pipe is used. When a heat pipe is provided directly under the heating coil 32, induction heating occurs, so a magnetic body 37 is interposed therebetween. The high thermal conductor 41 is thermally connected from the outer diameter to the inner diameter of the heating coil 32 in order to collect heat generated by the heating coil 32. Further, the high thermal conductor 41 is connected to the radiator 39.
[0017]
With the above configuration, the heat generated by the heating coil is guided to the radiator 39 by the high thermal conductor 41, so the cooling device 38 only needs to cool the radiator 39 intensively. Therefore, unlike the conventional example, it is not necessary to pass cooling air through the lower surface of the heating coil 32, and the pressure loss is small. Therefore, efficient cooling is possible even with an axial fan, resulting in an inexpensive induction heating device. It can be done.
[0018]
(Example 2)
FIG. 3 is a cross-sectional view of the induction heating apparatus in the second embodiment of the present invention, and the coil base is composed of resin ferrite 57. Other configurations are the same as those of the first embodiment. The thermal conductivity of the resin ferrite 57 is 1.5 W / Km, which is two orders of magnitude higher than a resin such as PET. Moreover, although the relative permeability of the resin ferrite 57 is about 10, since it is provided over the entire lower surface of the heating coil, its thickness (thickness from the lower portion of the heating coil) may be about 1 mm. Since the resin ferrite having high thermal conductivity is connected to the high thermal conductor 41 with the above configuration, the heat radiation of the heating coil 32 becomes extremely high, and more efficient cooling is possible. In addition, since the resin ferrite 57 shields the entire area of the lower surface of the heating coil 32, the high thermal conductor 41 is not induction-heated by a metal such as aluminum other than a heat pipe, resulting in efficient use of an inexpensive material or configuration. Cooling can be performed.
[0019]
(Example 3)
FIG. 4 is a cross-sectional view of the induction heating apparatus in the third embodiment of the present invention. The coil base is a resin ferrite 67, and the resin ferrite 67 is connected to a radiator 39. Other configurations are the same as those of the first embodiment. With the above configuration, a high thermal conductor is not necessary, but since the thermal conductivity of the resin ferrite 67 is lower than that of the high thermal conductor, the connection area with the radiator 39 is increased in this embodiment.
[0020]
Example 4
FIG. 5 is a cross-sectional view of an induction heating apparatus according to the fourth embodiment of the present invention. Resin ferrite 73 is provided on the upper surface of the inverter circuit board 74, and the inverter circuit component 71a and the inverter circuit component 71b are resin ferrite 73. It is thermally connected to the heat radiator 79 via. The inverter circuit and other components 75 are not connected to the resin ferrite. In this embodiment, the inverter circuit component 71a is a choke coil, and the inverter circuit component 71b is a resonance capacitor. The inverter circuit and other components 75 are components such as drive ICs that hardly generate heat. With the above configuration, cooling of components such as a choke coil and a capacitor that are difficult to mount on the radiator 79 can be thermally connected to the radiator 79 via the resin ferrite, so that more efficient component cooling is possible. Is. Further, since the inverter substrate 74 is covered with the resin ferrite 73, the noise generated from the inverter substrate 74 can be absorbed by the resin ferrite 73, and the effect of low noise can be obtained.
[0021]
The resin ferrite on the inverter board may be integrated with the resin ferrite that forms a coil base as in the second embodiment. Further, the entire surface of the inverter substrate 74 may be covered with the resin ferrite 73.
[0022]
(Example 5)
FIG. 6 is a cross-sectional view of the induction heating apparatus in the fifth embodiment of the present invention, and a resin ferrite 83 is also provided on the back surface of the inverter circuit board 84. With the above configuration, the heat generation of the pattern of the inverter circuit board 84 can be guided to the radiator 79, and the cooling efficiency can be further improved and the board can be reduced in size (insulation of the circuit pattern of the board). The distance can be small).
[0023]
【The invention's effect】
As described above, according to the first to fourth aspects of the present invention, cooling of the heating coil and the inverter circuit component can be realized simply and inexpensively.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an induction heating device in a first embodiment of the present invention. FIG. 2 is a top view of a radiator and an inverter circuit. FIG. Cross-sectional view [FIG. 4] Cross-sectional view of the induction heating apparatus in the third embodiment of the present invention [FIG. 5] Cross-sectional view of the induction heating apparatus in the fourth embodiment of the present invention [FIG. 6] FIG. 7 is a cross-sectional view showing a component configuration of a conventional induction heating apparatus. FIG. 8 is a view of a heating coil as viewed from below.
32 Heating coil 33 Inverter circuit 39, 79 Radiator 40, 71a, 71b Parts of inverter circuit 41 High thermal conductor 45 Switching element 46 Diode bridge 57, 67, 73, 83 Resin ferrite

Claims (4)

A heating coil, an inverter circuit having a switching element and a diode bridge and supplying a high-frequency current to the heating coil; a radiator mounted on at least one of the switching element and the diode bridge; and a lower surface of the heating coil A high thermal conductor that is provided to face the other components of the inverter circuit through a space and thermally connects the heating coil and the radiator; and at least one of the switching element and the diode bridge is provided An induction heating device thermally connected to the high thermal conductor by resin ferrite .   The induction heating device according to claim 1, wherein the heating coil is connected to the high thermal conductor through a resin ferrite.   The induction heating apparatus according to claim 1, wherein the heating coil is connected to the radiator through a resin ferrite. The induction heating apparatus according to claim 1 , wherein a part or the entire back surface of the inverter circuit is covered with resin ferrite.

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