JP2000048944A - Induction heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent leakage of high-frequency electromagnetic waves. SOLUTION: A coil 1 and a high-frequency power source part 2 are stored inside a box formed of a shield plate 5 being a metal thin plate. The magnetic flux generated by electric power supplied to the coil 1 and having a frequency around several-ten kHz passes through the shield plate 5 without being noticeably attenuated and permeates a heating element 3. Thereby, the heating element 3 is inductively heated. On the other hand, the harmonics (for instance 100 MHz or more) generated by the high-frequency power source part 2 are generally perfectly attenuated by the shield plate 5 and hence, do not leak outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating apparatus, and more particularly to an induction heating apparatus suitable for a heating cooking apparatus for heating and cooking an object to be heated such as food.

[0002]

2. Description of the Related Art Conventionally, the most widely used heating cooking apparatus utilizing induction heating is to dispose a coil directly below a flat plate and to heat the pot placed on the plate by induction heating. It is an electromagnetic cooker that cooks food inside. In the electromagnetic cooker, a plate formed of an insulator such as a ceramic is used so that the plate itself does not become a load for induction heating and has heat resistance.

[0003]

In such an induction heating device, a high-frequency current having a frequency of about 10 kHz to several tens of kHz flows through the coil. In the power supply unit that supplies such a high-frequency current, a higher-order frequency component is further generated, and the coil functions as an antenna, and an electromagnetic wave containing such a high-frequency component is radiated to the surroundings.

[0004] In general, in electric and electronic equipment, measures are often taken to suppress the leakage of electromagnetic waves to the outside by providing appropriate shielding as described above. Since the source is also an electromagnetic wave radiation source, it has been difficult to shield unwanted electromagnetic waves. The present invention has been made in view of such a point, and a main object of the present invention is to provide an induction heating device that is effective for preventing leakage of high-frequency electromagnetic waves to the outside.

[0005]

Means for Solving the Problems, Embodiments of the Invention, and Effects of the Invention The induction heating apparatus according to the present invention, which has been made to solve the above problems, comprises: a) a coil; C) a heating element that is induction-heated by the coil; d) a heating element that is disposed between the heating element and the coil to substantially prevent the passage of magnetic flux generated by the coil. And a shielding member made of a metallic material so as not to obstruct it.

The shielding member may be, for example, a thin metal plate having no opening and having a thickness of about 0.1 mm, a metal plate having small holes perforated with an appropriate opening ratio, and the like.

In the present invention, when the power supply means supplies high frequency power to the coil, an alternating magnetic flux is generated in the coil, and this magnetic flux induces an eddy current in the heating element to generate heat. For example, if the pan itself containing the object to be heated is the heating element, heat can be directly applied to the object to be heated. In addition, air or liquid (water or oil, etc.) existing between the heating element and the object to be heated
The object to be heated can also be heated via. The shielding member allows electromagnetic waves (lines of magnetic force) in the vicinity of the frequency of the high-frequency power supplied to the coil to pass without being attenuated,
Electromagnetic waves having the higher order frequencies are greatly attenuated.
Therefore, according to the present invention, it is possible to prevent excessive leakage of unwanted electromagnetic waves without significantly lowering the efficiency of induction heating.

In a preferred embodiment of the induction heating apparatus according to the present invention, the power supply means and the coil may be covered with a shielding member except for a power supply line for supplying a commercial alternating current to the power supply means. According to this configuration, the high-frequency electromagnetic waves leaked to the outside by the shielding member can be greatly attenuated.

Further, in the induction heating apparatus according to the present invention, a substantially hermetic heating chamber is formed by a shielding member, a coil is arranged outside the heating chamber, and a heating element is installed inside the heating chamber. In addition, a configuration can be employed in which a microwave generation unit for supplying a microwave into the heating chamber is provided. In this configuration, the object to be heated housed in the heating chamber is heated by both the radiant heat radiated from the heating element and the microwave supplied from the microwave generating means. Since the shielding member allows the magnetic flux generated by the coil to pass therethrough, the heating element is induction heated, but the microwave is prevented from leaking from the heating chamber by the shielding member.

Further, in the induction heating apparatus according to the present invention, the belt wound around the two rollers, the heating element mounted on the belt, and the belt running under the heating element with the belt interposed therebetween. And a plurality of coils arranged in parallel in the direction, and the belt can function as a shielding member. Specifically, for example, the belt can be formed by attaching a metal thin film to the surface of an elastic member such as rubber.

Further, in the induction heating apparatus according to the present invention, the coil may be covered with a synthetic resin material, and the shielding member may be a thin metal film formed on the surface of the covering layer. According to this configuration, the metal thin film closes the pinhole of the coating layer made of the synthetic resin in addition to simply suppressing the leakage of the undesired electromagnetic waves. Reaching can be reliably prevented.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a heating and cooking apparatus according to a first embodiment (hereinafter referred to as "embodiment 1") of an induction heating apparatus according to the present invention will be described.

FIG. 1 is a schematic sectional view of a heating cooking apparatus according to this embodiment. In this embodiment, a top plate 7 made of a heat-resistant resin, ceramic, or the like is detachably attached to an upper surface opening of a housing 6 made of an insulator such as a synthetic resin. 7. The heating means includes a coil 1 wound in a plate spiral shape, a high-frequency power supply 2 for supplying high-frequency power to the coil 1, and a heating element 3.
It is composed of The high-frequency power supply unit 2 is supplied with commercial power from the outside through a commercial power supply line 8, and a noise filter 4 for removing high-frequency noise superimposed on the power supply voltage is provided in the middle thereof. I have.
The coil 1 and the high-frequency power supply unit 2 are both covered by a box-shaped shielding plate 5 without any gap. The shielding plate 5 is a thin metal plate made of, for example, stainless steel SUS304.

In the cooking device, a commercial power supply current is supplied to the high-frequency power supply unit 2 via the commercial power supply line 8, and a high-frequency current having a frequency of about several tens of kHz is supplied from the high-frequency power supply unit 2 to the coil 1 during heating. Supplied. As a result, an alternating magnetic flux is generated in the coil 1, and the magnetic flux is applied to the shielding plate 5.
, And through the heating element 3. At that time, a large number of eddy currents are generated in the heating element 3, and the heating element 3 itself generates heat due to the eddy current loss. The high-frequency power supply unit 2 is configured to include, for example, an inverter circuit in order to efficiently supply heating power, and generates an electromagnetic wave having a harmonic component of the high-frequency current. Such an electromagnetic wave is mainly emitted from the coil 1 itself to the surroundings, but is blocked by the shield plate 5 and hardly leaks from the shield plate 5 to the outside.

Here, the shielding effect of the shielding plate 5 will be described with reference to Table 1 below. Table 1 is a table showing the relationship between the thickness of the shielding plate and the shielding effect of high-frequency electromagnetic waves. For example, when the plate thickness is 0.1 mm, 2
82% of the 5 kHz frequency component passes and only 18% of the attenuation at the shielding plate. In contrast, electromagnetic waves having a frequency of 150 MHz are almost completely shielded. That is, by using such a shielding plate, harmonic components can be shielded without impairing induction heating.

[0016]

[Table 1]

Next, a heating and cooking apparatus according to a second embodiment (hereinafter, referred to as "embodiment 2") of the present invention will be described with reference to FIG. This heating cooking device is a commercial cooking device suitable for performing a large number of cooking operations simultaneously.

In the heating and cooking apparatus of the second embodiment, an endless belt 12 is stretched between two rollers 10 and 11 installed horizontally, and a pan-shaped belt as described in the first embodiment is placed on the belt 12. Are placed side by side in the belt running direction.
A plurality of coils 1 are fixedly arranged below the upper surface of the belt 12 in the belt running direction, and each coil 1 is supplied with high-frequency power from a high-frequency power supply unit 2.

One roller 10 is driven to rotate at a predetermined speed by a motor (not shown). With this, belt 1
2 runs at a predetermined speed, and the other roller 11 is driven.
While the heating element 3 placed on the belt 12 moves as the belt 12 travels, the heating element 3 is heated inductively by the magnetic flux generated from the different coils 1 sequentially. .

The belt 12 has a structure in which a metal thin film is formed on the surface of, for example, a rubber belt by vapor deposition. Therefore, the belt 12 itself has a function of a shielding plate. Also,
Oil and food fragments scattered from the contents in the heating element 3 to the surroundings adhere to the upper surface of the belt 12, but are scraped off by the squeegee 13.

Next, a heating and cooking apparatus according to a third embodiment (hereinafter referred to as "embodiment 3") of the induction heating apparatus according to the present invention will be described. The heating and cooking apparatus according to the third embodiment includes both the above-described induction heating device and the microwave heating device similar to a microwave oven as heating means.

FIG. 3 is a schematic sectional view of a heating and cooking apparatus according to the third embodiment. A rectangular parallelepiped heating chamber 22 made of an insulator such as ceramic or heat-resistant resin is formed in the housing 21, and a front opening of the heating chamber 22 can be substantially closed by a door 23. A magnetron 25 is attached to the rear wall surface of the heating chamber 22 via a waveguide 24, and a turntable 26 for mounting an object to be heated such as food is rotatable by a motor 27 at the bottom of the heating chamber 22. It is provided in.

A coil 28 is wound around the outside of the heating chamber 22 so as to go around the upper surface, the side surface and the lower surface, and the coil 28 is supplied with high-frequency power from a high-frequency power supply unit 29 provided at the rear. It is supposed to be. Further, inside the heating chamber 22, a square tubular heating element 30 whose front side and rear side are open with a predetermined gap from the inner wall surface of the heating chamber 22 is installed.

A shielding plate 31 is attached to the inner surface of the heating chamber 22 and the inner surface of the door 23 except for the mounting portion of the waveguide 24. The shielding plate 31 can be, for example, a metal plate similar to the shielding plate in the first embodiment. That is, the shielding plate 31
Prevents the microwave transmitted from the magnetron 25 into the heating chamber 22 from leaking outside while allowing the magnetic flux generated from the coil 28 to pass through.

In the above configuration, when a high-frequency current flows from the high-frequency power supply unit 29 to the coil 28, the magnetic flux generated by the coil 28 passes through the shielding plate 31 and penetrates the heating element 30.
As a result, the heating element 30 generates heat, and the object to be heated placed on the turntable 26 is heated and cooked by the radiant heat. When the magnetron 25 is driven, microwaves are sent into the heating chamber 22 through the waveguide 24,
This also heats the object to be heated. By using both of them, heating can be performed quickly, and the surface of the object to be heated can be burned by the heat from the heating element 30.

In addition to a metal plate having no opening, a metal plate having many small holes (a so-called punching metal) may be used as the shielding plate 31. In addition, even if the metal plate has a relatively large thickness, a metal having a high resistivity is unlikely to be a load for induction heating, and thus can be used as the shielding plate 31.

Next, a heating and cooking apparatus according to a fourth embodiment (hereinafter referred to as "embodiment 4") of the present invention will be described with reference to FIG. This heating cooking device is a cooking device for carrying out fried cooking of food using edible oil. As described above, not only the electromagnetic shielding effect of the metal shielding plate but also the uniformity of the metal thin film formed by plating or the like is provided. Utilize sex.

Inside the deep pot 40, a coil support 43 in which a coil 41 wound in a spiral shape is molded with a heat-resistant synthetic resin layer 42 is fixedly provided.
On the surface of the synthetic resin layer 42, a metal thin film 44 is formed by electroless plating or the like. In addition, a flat donut-shaped heating element 45 is attached to the upper portion of the coil support 43. The heating element 45 has a large surface area due to the flat shape.

When high-frequency power is supplied to the coil 41 from a high-frequency power supply (not shown), the magnetic flux generated from the coil 41 passes through the heating element 45, and the heating element 45
Generates heat. The cooking oil contained in the pot 40 is heated by heat exchange with the heating element 45 so that the heating element 45 is immersed, and the food put into the cooking oil is fried and cooked.

Although the above-mentioned mold made of a synthetic resin material is inexpensive to manufacture, on the other hand, pinholes are liable to occur during the manufacturing process. However, as described above, the metal thin film 4 formed on the surface of the synthetic resin layer 42 by plating or the like.
Since the pinhole 4 closes the pinhole, the liquid tightness of the internal coil 41 is improved, and it is possible to prevent the surrounding oil from being in contact with the coil 41 and the coil 41 from being easily corroded.

Next, a liquid heating apparatus according to a fifth embodiment (hereinafter, referred to as "embodiment 5") of the present invention will be described with reference to FIG. This liquid heating apparatus is constructed by attaching a thin metal body 52 to a cylindrical metal pipe 51 by welding. A coil 5 is provided around the cylindrical body 52.
3 is wound, and a cylindrical heating element 54 is accommodated inside the cylindrical body 52. When high frequency power is supplied to the coil 53 from a high frequency power supply unit (not shown), the coil 5
3 passes through the cylindrical body 52 and passes through the heating element 54.
, And the heating element 54 generates heat due to eddy current loss. Water and other liquids are circulated in the metal pipe 51, and the liquids are heated by exchanging heat with the heating element 54.

Conventionally, since the cylindrical body 52 was formed of an insulator such as ceramics, joining by welding could not be performed. However, according to the present invention, metal can be used for the cylindrical body 52. Can be joined by welding. For this reason, manufacturing becomes easy and cost can be reduced.

The above embodiment is merely an example, and it is apparent that changes and modifications can be made within the spirit of the present invention.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a cooking device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a heating cooking device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a heating cooking device according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a heating cooking device according to a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram of a liquid heating device according to a fifth embodiment of the present invention.

[Explanation of symbols]

 1, 28, 41 ... coil 2, 29 ... high frequency power supply 3, 30, 45 ... heating element 4 ... noise filter 5, 31 ... shielding plate 6 ... housing 7 ... top plate 8 ... commercial power line 10, 11 ... roller DESCRIPTION OF SYMBOLS 12 ... Belt 22 ... Heating chamber 23 ... Door 25 ... Magnetron 43 ... Coil support 44 ... Metal thin film

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshiyuki Hirata 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term in Sanyo Electric Co., Ltd. (reference) 3K051 AA02 AA08 AB02 AB04 AB05 AB13 AC09 AC10 AD23 AD27 AD35 AD40 CD42 CD43 CD44 3K059 AA02 AA08 AA15 AB04 AB13 AB19 AB20 AC09 AC10 AD23 AD27 AD35 CD44 CD52 CD75 3K086 AA03 AA05 BA03 BA08 BB02 BB03 CB04 CB12 CB15 CC01 CC06 EA06 FA03 3K090 AA03 A03 EA02 EB01 BA01 BA01 BA01 BA01 BA03 CA12 CB02 CC03 DA02 DA23

Claims (5)

[Claims] A) a coil; b) power supply means for supplying high-frequency power to the coil; c) a heating element induction-heated by the coil; d) a heating element between the heating element and the coil. And a shielding member made of a metallic material that does not substantially prevent passage of magnetic flux generated by the coil. 2. The induction heating apparatus according to claim 1, wherein the power supply means and the coil are covered with a shielding member except for a power supply line for supplying power to the power supply means. 3. A heating chamber capable of being substantially sealed by the shielding member is formed, and a coil is disposed outside the heating chamber.
2. The induction heating apparatus according to claim 1, wherein a heating element is provided inside the heating chamber, and a microwave generating means for supplying a microwave into the heating chamber is provided. 4. A heating device having a belt wound around two rollers, a plurality of heating elements mounted on the belt, and a plurality of coils disposed below the heating element with the belt interposed therebetween in a belt running direction. 2. The induction heating device according to claim 1, wherein a plurality of belts function as the shielding member. 3. 5. The induction heating apparatus according to claim 1, wherein the coil is covered with a synthetic resin material, and the shielding member is a metal thin film formed on a surface of the covering layer.