JPS6247193Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an external casing structure for reducing electromagnetic interference generated by an electromagnetic induction cooking device.

Structure of conventional example and its problems The structure of the external casing of a conventional electromagnetic cooker is as shown in FIG. 1 or 2, for example.

A brief explanation of those configurations and problems are given below. The electromagnetic cooker shown in FIG. 1 includes a pot mounting plate 2 on which a loaded pot 1 is placed, and an electrically insulating material that holds the pot mounting plate 2 and surrounds an internal heating coil 3, static power converter 4, etc. It consists of an external casing 5 molded with. The problem in this case is that the high frequency and high density magnetic field with a frequency of about 20 to 50 KH radiated downward from the heating coil 3 and the electromagnetic field generated from the high frequency components of the high frequency converter easily leak to the outside of the device. If an iron plate, aluminum foil, etc. is placed close to the bottom of the external housing 5, there is a risk of generating heat due to the magnetic field of the heating coil 3. be. These problems are caused by the fact that the external casing 5 is made of electrically insulating resin or the like and therefore has no magnetic shielding effect.

Next, in the conventional configuration shown in FIG. 2, a conductive metal plate 6 is laid inside the bottom of the external casing 5 made of electrically insulating material in the configuration of the device shown in FIG. This is the layout of the parts of the conversion device 4.

The problem with this configuration is that the electrical components of the high-frequency power converter 4 (for example,
(chiyoke coils, resonant capacitors, heat dissipation fins for switching elements, etc.) are arranged, so in order to ensure sufficient insulation distance between the components and the conductive metal 6, there are various restrictions on the arrangement of components inside the device and the method of fixing them. This is a major hindrance in terms of making the entire device smaller and thinner, and the conductive metal plate 6 must be subjected to various processing for fixing the article, which increases manufacturing costs. be.

Purpose of the invention The present invention solves the above-mentioned drawbacks of the conventional technology.
The purpose of the present invention is to provide an external casing configuration that effectively reduces the amount of noise and reduces the size and thickness of devices.

Structure of the invention In order to achieve the above object, the electromagnetic induction cooking device of the invention has a structure in which the cross-sectional structure of part or all of the external casing has a multilayer structure in which a conductive material is sandwiched between electrically insulating materials on both sides. This makes it possible to easily shield the electromagnetic field generated by heating coils or other high-frequency power conversion devices using the external casing, without creating new constraints to ensure insulation distance in the arrangement of electrical components inside the device. This makes it possible to make the electromagnetic cooker extremely thin, and each electrical component is mounted on the electrically insulating material inside the external casing, which has a multilayer structure. If resin is used, the structure for attaching parts can be made simple and inexpensive, and mass production can be easily achieved.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 3 shows a cross-sectional configuration of an embodiment based on the present invention. In FIG. 3, the load pan 7 is held by a pan mounting plate 8, and the internal high-frequency power converter 13 is It surrounds parts, various electrical parts, and mechanical parts. The external casing 11 is made of resin or the like having electrical insulation properties, and includes protrusions that hold the heating coil 9 and the heating coil holding plate 10, and various electrical parts (for example, for electronic control) that constitute the high-frequency power converter 13. Printed wiring board 13a, York coil 13b, Switching element cooling fin 1
3c, etc.) are provided inside the external housing 11, and are directly fixed thereon.

Furthermore, a conductive metal plate 12 made of an aluminum plate, a stainless steel plate, etc. is inserted into the bottom of the external housing 11, and when viewed in cross section, it has a three-layer structure as shown in FIG. It's getting old.

The effects of the above configuration will be explained below.

The external casing is made of heat-resistant resin with good moldability, and serves as a holding member for the pot mount plate 8 and a fixing member for various internal parts. It is also used as an electric shock prevention member. Furthermore, the external housing 11 is provided with an intake port and an exhaust port for cooling, and serves as an important component of the cooling system.

In this embodiment, the external casing 11 having the above-mentioned functions is integrally molded and can be molded from resin very easily. Further, in this embodiment, the conductive metal plate 12 is located inside the bottom surface of the external casing.
It is embedded by insertion or integral molding,
This conductive metal plate has an extremely large electromagnetic shielding effect as described below. That is, load pot 7
, it is necessary to radiate a high frequency, high magnetic flux density magnetic field from the heating coil 9 toward the bottom of the loaded pan 7. At this time, magnetic flux is also radiated from the bottom of the heating coil 9. The magnetic flux from this bottom is
Although it is possible to shield to some extent by magnetic shielding means such as laying a ferrite core under the heating coil 9, it is difficult and time-consuming to completely suppress the magnetic field. Therefore, if the device is placed on a steel plate as shown by A in Fig. 3 or a plate covered with aluminum foil, the leakage magnetic field of the magnetic flux generated from the lower part of the heating coil 9 may cause the Steel plates, aluminum foil, etc. may generate heat, creating a dangerous situation. Also, if a TV or other electronic device is accidentally placed at the bottom of the induction cooker, the heating coil 9
There is also a risk that leakage magnetic fields from the electronic devices may cause them to malfunction or be damaged.

These things occur when other electronic devices are very close to the electromagnetic cooker, but even if the other electronic devices are far away from the electromagnetic cooker,
High-frequency noise that leaks to the outside through power supply wires, that is, conduction noise, may adversely affect other electronic devices. Even in this case, this conduction noise can be reduced by connecting the conductive metal plate to the low frequency AC power line via a capacitor. In addition, regarding the radiation noise transmitted through the space and radiated to the outside, a three-layer structure based on the present invention is adopted for the bottom and side surfaces of the external casing 11, as shown in Fig. 4, and as shown in Fig. 5. As shown in FIG. 2, parts of the high-frequency power converter to which particularly steep high-frequency large current and high voltage waveforms are applied (for example, the switching element 14 and its cooling fins 15, etc.) are surrounded by a conductor 16 made of aluminum or the like. This can be easily reduced by shielding it in combination with the conductive metal plate 12 on the bottom. In particular, the point I would like to emphasize regarding the effects of this configuration is that when the above electromagnetic shielding measures are taken,
In any of the cases shown in FIG. 5, the inner surface of the housing 11, that is, the component mounting surface, is made of electrically insulating material. For example, as shown in FIG. This means that it is extremely easy to insulate and attach it to the external casing 11. Conversely, the component mounting surface (external housing 1
1) is made of a conductive metal material, the conductive metal plate (shielding plate) 16 is made of a conductive metal material unless the live metal parts are insulated by other electrically insulating parts and attached to the external housing 11. It becomes the same potential as component 15,
It becomes a charging component. In this case, when placing other electrical parts or conductive members around this, there will be severe spatial restrictions on electrical insulation. In this case, the number of parts used as electrically insulating parts increases, which increases assembly costs, and the space (height) occupied by the parts increases by the height of the insulator. Considering that these restrictions are extremely serious problems for electromagnetic induction cooking appliances, which are desired to be smaller and thinner, the above-mentioned effect is extremely effective.

As described above, according to this embodiment, the electromagnetic field generated from the heating coil of the electromagnetic cooker or the high-frequency power converter can be easily reduced without placing any restrictions on the arrangement of internal electrical or metal parts. This will have a huge effect on making cookers smaller and thinner. In addition, in this example, the three-layer structure of the electrically insulating material and the conductive metal plate of the external casing can be manufactured by integral molding or by inserting the conductive metal plate after molding the electrically insulating material, but only the insulating material can be used. It also has the effect of increasing mechanical strength compared to the external casing.

Effects of the invention As described above, according to the invention, the following effects can be obtained.

(1) Magnetic flux leaking from the bottom of the heating coil to the outside of the electromagnetic cooker can be easily shielded by the external casing.

(2) At least inside the external casing (internal parts side)
However, since it is made of electrically insulating material, there is no need for insulation between the live parts and the mounting part (casing), and the live parts can be directly attached to the external case, allowing for higher density parts arrangement. With,
The reliability of the insulation of internal electrical components from the outside increases.

(3) Due to the effects (1) and (2) above, it is possible to make the electromagnetic cooker smaller, especially thinner.

(4) High-frequency conduction noise and radiation noise generated from electromagnetic cookers can be reduced.

[Brief explanation of the drawing]

1 and 2 are sectional views of the casing structure of a conventional electromagnetic cooker, FIG. 3 is a sectional view of the casing structure of an electromagnetic cooker which is an embodiment of the present invention, and figs. 4 and 5. The figure is a sectional view of the housing structure of an electromagnetic cooker according to another embodiment of the present invention. 8... Pot mounting plate, 9... Heating coil, 11...
External casing, 12... conductive material, 13... high frequency power conversion device.

Claims (1)

[Claims for Utility Model Registration] (1) A heating coil, a high-frequency power converter, a pot mounting plate, and an external casing that encloses internal parts together with the pot mount plate, and includes a heating coil, a high-frequency power converter, a pot mounting plate, and an external casing that surrounds internal parts, and The electromagnetic induction heating cooker has a multilayer structure made of an electrically insulating material and a conductive material, and the multilayered structure is such that the inner side of the external casing is made of the electrically insulating material. (2) The scope of the utility model registration claim, which has a structure in which an external casing having a multilayer structure of the electrically insulating material and the conductive material is disposed at least below the location where the high-frequency power converter or the heating coil is disposed. The electromagnetic induction heating cooker according to item 1.