JP2003151745A - Induction heating cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction heating cooker having an improved heating efficiency by reducing a magnetic transfer loss. SOLUTION: This induction heating cooker comprises a high frequency inverter 12, an induction heating coil 13 connected with the high frequency inverter 12, an object 15 to be induction-heated by high frequency magnetic field generated by the induction heating coil 13, and a metallic body 19 arranged approximately coaxially with the induction heating coil 13 for preventing leakage magnetic field. Magnetic field pushed back by repulsion magnetic field of the object 15 to be heated is contained by magnetic field of the metallic body 19 for reducing the magnetic transfer loss between the induction heating coil 13 and the object 15 to be heated.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an induction heating cooker used in general households.

[0002]

2. Description of the Related Art Generally, in an induction heating cooker, a high frequency magnetic field is generated from an induction heating coil and an object to be heated such as a cooking pot is heated by an eddy current caused by electromagnetic induction.

An example of a conventional induction heating cooker will be described below with reference to FIG. In the figure, 1 is a high-frequency inverter, 2 is an induction heating coil connected to the high-frequency inverter 1, 3 is a magnetic material arranged below the induction heating coil 2, and 4 is a cooking pot or the like that is induction-heated by the induction heating coil 2. An object to be heated, 5 is a top plate on which the object to be heated 4 is placed, 6 is an AC power source, and 7 is a housing containing the high frequency inverter 1, the induction heating coil 2, and the like.

In this structure, a high-frequency magnetic field is generated from the induction heating coil 2 by the high-frequency current supplied from the high-frequency inverter 1, and the object 4 to be heated is heated due to the eddy current caused by electromagnetic induction so that cooking can be performed. . Further, the magnetic body 3 below the induction heating coil 2 confines the high frequency magnetic field and directs it toward the heated body 4.

[0005]

However, in the above-mentioned conventional structure, especially when the heated body 4 is made of a non-magnetic metal, the repulsive magnetic field caused by the eddy current flowing in the heated body 4 is generated. The magnetic field, which becomes large and should normally go to the heated body 4, does not effectively pass through the heated body 4. Then, the magnetic field pushed back by the repulsive magnetic field from the heated body 4 has a distribution that leaks into the space from between the induction heating coil 2 and the heated body 4, as shown in FIG.
The magnetic field leaking into this space is generally called a leak magnetic field. This leakage magnetic field does not contribute to the heating of the object to be heated 10 and thus causes a magnetic transmission loss that is a factor of reducing the heating efficiency.

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned conventional problems, and an object thereof is to provide an induction heating cooker with improved heating efficiency by reducing the magnetic transmission loss between the induction heating coil and the object to be heated. It was done.

[0007]

In order to achieve the above object, the induction heating cooker of the present invention is provided with a metal body for preventing a leakage magnetic field so as to be substantially concentric with the induction heating coil.

As a result, the magnetic field pushed back by the repulsive magnetic field from the object to be heated can be confined by the magnetic field from the metal body, and an induction heating cooker with improved heating efficiency can be provided.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 is a high frequency inverter, an induction heating coil connected to the high frequency inverter, an object to be heated by induction heating by a high frequency magnetic field generated from the induction heating coil, and an induction heating coil. By using an induction heating cooker having a metal body that is arranged so as to be substantially concentric with the heating coil and that blocks a leakage magnetic field, the magnetic field pushed back by the repulsive magnetic field from the heated object is confined by the magnetic field from the metal body Therefore, it is possible to provide an induction heating cooker with improved heating efficiency.

According to the second aspect of the invention, the induction heating cooker according to the first aspect is arranged so that the metal body is tubular and the central axis of the tubular body is substantially concentric with the induction heating coil. It is possible to provide an induction heating cooker in which the effect of trapping a magnetic field is improved and the heating efficiency is further improved.

According to a third aspect of the present invention, the induction heating cooker according to the first aspect is arranged such that the metal body has a dish shape for accommodating the induction heating coil, and the central axis of the metal body is substantially concentric with the induction heating coil. By this, the effect of confining the leakage magnetic field is improved, the heating efficiency is increased, and the metal body can also serve as the fixing of the induction heating coil.

The invention according to claim 4 is the induction heating cooker according to claim 1 in which the metal body is composed of a single wire or a wire consisting of a plurality of wires, whereby the effect of confining the leakage magnetic field is improved and the heating efficiency is improved. In addition to increasing the cost, the material cost can be reduced because no scraps are generated as a metal body.

According to a fifth aspect of the present invention, the induction heating cooker according to the first aspect is configured by forming the metal body by twisted wires insulated from each other, and in particular, metal caused by current flowing through the metal body is used. The loss of the body itself can be reduced.

According to a sixth aspect of the present invention, the metal body is arranged on a mounting surface on which the body to be heated is mounted.
By using the induction heating cooker according to any one of items 1 to 3, in particular, by using a metal body that matches the shape of the object to be heated, heating efficiency can be increased regardless of the shape of the object to be heated.

[0015]

(Embodiment 1) The first means of the present invention will be described below with reference to FIGS. In FIG. 1, 1
2 is a high frequency inverter, 13 is an induction heating coil connected to the high frequency inverter 12, and 14 is an induction heating coil 13.
A magnetic material arranged below the object, 15 is a heated object such as a cooking pot that is induction-heated by the induction heating coil 13, 16 is a top plate on which the heated object 15 is placed, 17 is an AC power source, 1
Reference numeral 8 is a housing that houses the high-frequency inverter 12, the induction heating coil 13 and the like, and 19 is a ring-shaped metal body that is arranged so as to be substantially concentric with the induction heating coil 13 and that blocks a leakage magnetic field.

The magnetic bodies 14 are arranged in a radial shape on the side of the induction heating coil 13 opposite to the body to be heated 15 in a rod shape. In addition, the magnetic material 14 is formed around the induction heating coil 13.
Has a shape in which the end portion of is bent toward the heated body 15 side.

The metal body 19 is provided inside the housing 18, and is arranged at a position outside the induction heating coil 13, as shown in FIG.

In the above structure, particularly when the heated body 15 is made of a non-magnetic metal, the repulsive magnetic field from the heated body 15 against induction heating becomes large as described in the conventional example, and originally, The magnetic field that should go to the heated body 15 is pushed back and leaks from between the induction heating coil 13 and the heated body 15.

However, in this embodiment, the leakage magnetic field is easily directed to the heated body 15 side by the end portion of the magnetic body 14. Furthermore, the magnetic bodies 14 arranged radially
The magnetic field leaked from the space induces an induced current inside the metal body 19 to generate a magnetic field 20 as shown in FIG. Since the magnetic field generated from the metal body 19 acts in the direction of impeding the leakage magnetic field, it is possible to increase the amount of the magnetic field toward the heated body 15 by confining the magnetic field. Therefore, the magnetic transmission loss can be suppressed and the heating efficiency can be improved.

According to the experiments by the inventors, in the case of using a cooking pot made of aluminum which is a non-magnetic metal,
As shown in (Table 1), the temperature rise of the water in the cooking pot in the case where the metal body 19 was present was about 1% higher than that in the case where the metal body 19 was not provided (heating). The conditions are the same).

[0021]

[Table 1] In the present embodiment, the magnetic body 14 has a rod shape, but it may have a fan shape having the induction heating coil 13 as its apex, a donut shape substantially concentric with the induction heating coil 13, or a circular shape. It doesn't matter.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are designated by the same reference numerals, the description thereof will be omitted, and only different points will be described. The metal body 21 has a tubular shape and is arranged in the housing 18 so that its central axis is substantially concentric with the induction heating coil 13.

Also in the above configuration, as in the first embodiment,
The stray magnetic field is easily directed to the heated body 15 side by the end of the magnetic body 14, and an induced current is induced inside the metal body 21,
Generate a magnetic field. However, in this embodiment, since the leakage magnetic field has a surface in the direction of distribution, the magnetic field confinement effect is enhanced. This effect becomes more remarkable as the height of the metal body 16 increases. Therefore, the heating efficiency can be further improved.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS. The same parts as those in the first embodiment are designated by the same reference numerals, the description thereof will be omitted, and only different points will be described. The metal body 22 was formed into a dish shape for accommodating the induction heating coil 13, and was arranged in the housing 18 so that its central axis was substantially concentric with the induction heating coil 13. That is, the induction heating coil 13 is housed in the metal body 22, and in this state, the outer circumference of the induction heating coil 13 is covered by the peripheral wall of the metal body 22.

Also in the above configuration, as in the first embodiment,
The stray magnetic field is easily directed to the heated body 15 side by the end of the magnetic body 14, and an induced current is induced inside the metal body 22,
Generate a magnetic field. However, in this embodiment, since the leakage magnetic field has a surface in the direction of distribution, the magnetic field confinement effect is enhanced. This effect becomes more remarkable as the height of the peripheral wall of the metal body 22 increases. Therefore, the heating efficiency can be further improved.

In general, the induction heating coil 13 is
As shown in FIG. 6, the coil base 13a is fixed to the housing 18 while keeping a distance from the top plate 16.
In this embodiment, as shown in FIG. 7, the metal body 22 has a dish shape. For this reason, the metal body 22 can directly or indirectly house the induction heating coil 13, and can also serve as a structure for holding the induction heating coil 13. Therefore, the coil base 13a is unnecessary.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIG. In this embodiment, the metal body 23 is not a punched metal plate or the like, but is a ring-shaped conductor made of a single wire or a plurality of wires. The figure shows the case where a plurality of conductors 24 are used. The configuration of the induction heating cooker is the same as that of the first embodiment, and thus the description thereof is omitted.

In the above structure, as in the first embodiment,
The presence of the metal body 23 makes it possible to improve the heating efficiency.
In addition, in the present embodiment, the metal body 23 is not a punched metal plate or the like but a ring-shaped conductor wire made of a single wire or a plurality of wires. Can be realized. In addition, in the present embodiment, the metal body 23 is composed of a plurality of conductors 24, but the same effect can be obtained even if the metal body 23 is composed of only one conductor 24.

Further, as shown in FIG. 9, the same effect can be obtained even if the conductor 25 is covered with an electric insulator 26 as the metal body 23. In this case, the conductor 25 may be either a single wire or a plurality of wires.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described with reference to FIG. In this embodiment, the metal body 27 is composed of stranded wires insulated from each other. Stranded wire is a conductor wire 2 consisting of a single wire or multiple wires.
8 is covered with an electrical insulator 29, which is twisted into a ring shape. In addition, the configuration as an induction heating cooker,
The description is omitted because it is the same as in the first embodiment.

Also in the above configuration, as in the first embodiment,
The leakage magnetic field induces an induced current inside the metal body 27 to generate a magnetic field, so that a magnetic field confinement effect can be obtained and heating efficiency can be improved. The magnetic field generated from the induction heating coil 13 used for induction heating is 20 to
It has a high frequency of 50 kHz and the metal body 2
The induced current induced inside 7 also has a high frequency. The high-frequency current concentrates on the surface of the conductor wire 28 due to the skin effect, but in the present embodiment, the conductor wire 25 is
Since the stranded wire is insulated by the electric insulator 29, the surface area of the entire conductor 28 is large and the portion through which the induced current flows is wide. Therefore, the resistance to the induced current is reduced and the loss of the metal body 27 itself caused by the induced current can be reduced.

(Sixth Embodiment) Next, a sixth embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are designated by the same reference numerals, the description thereof will be omitted, and only different points will be described. The metal body 30 is arranged on the mounting surface of the top plate 16 on which the body to be heated 15 is mounted. In addition,
Although the metal body 30 is provided outside the housing 18, the first embodiment
Similarly, the induction heating coil 13 and the induction heating coil 13 are arranged so as to be substantially concentric with each other and to be positioned outside the induction heating coil 13. The metal body 30 may be any of the metal bodies in each embodiment, and the shape is not limited to that of each embodiment.

Also in the above configuration, as in the first embodiment,
The stray magnetic field is easily directed to the heated body 15 side by the end of the magnetic body 14, and an induced current is induced inside the metal body 30,
By generating a magnetic field, a magnetic field confinement effect can be obtained and heating efficiency can be improved. In addition, according to the shape of the object to be heated 15, for example, in a cooking pot with a small diameter, the metal member 3
By making the diameter of 0 small, the magnetic field confinement effect can be obtained regardless of the cooking pot shape, and the heating efficiency can be improved.

[0034]

As described above, according to the induction heating cooker of the present invention, the heating efficiency can be improved by reducing the leakage magnetic field by the metal body.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an induction heating cooker according to a first embodiment of the present invention.

FIG. 2 is a perspective view of an induction heating coil and a metal body in the induction heating cooker.

FIG. 3 is a magnetic field distribution map during induction heating in the induction heating cooker.

FIG. 4 is a schematic configuration diagram of an induction heating cooker according to a second embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of an induction heating cooker according to a third embodiment of the present invention.

FIG. 6 is an explanatory view of a general holding configuration of an induction heating coil in the induction heating cooker.

FIG. 7 is a perspective view of an arrangement configuration of an induction heating coil and a metal body in the induction heating cooker.

8A is a perspective view of a metal body according to a fourth embodiment of the present invention, and FIG. 8B is a sectional view taken along line AA of FIG.

FIG. 9 is a schematic configuration diagram showing another example of the metal body.

FIG. 10 is a schematic configuration diagram of a metal body according to a fifth embodiment of the invention.

FIG. 11 is a schematic configuration diagram of an induction heating cooker according to a sixth embodiment of the present invention.

FIG. 12 is a schematic configuration diagram of a conventional induction heating cooker.

FIG. 13 is a magnetic field distribution map during induction heating in the induction heating cooker.

[Explanation of symbols]

12 high frequency inverter 13 Induction heating coil 14 Magnetic material 15 Heated object 16 top plate 19, 21, 22, 23, 27, 30 Metal body

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takahiro Miyauchi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Yuji Fujii             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Akira Kataoka             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 3K051 AB13 CD43 CD44

Claims (6)

[Claims] 1. A high-frequency inverter, an induction heating coil connected to the high-frequency inverter, an object to be induction-heated by a high-frequency magnetic field generated from the induction heating coil, and an induction heating coil arranged so as to be substantially concentric with the induction heating coil. An induction heating cooker having a metal body that blocks a leakage magnetic field. 2. The induction heating cooker according to claim 1, wherein the metal body has a cylindrical shape and is arranged so that its central axis is substantially concentric with the induction heating coil. 3. The induction heating cooker according to claim 1, wherein the metal body has a dish shape for accommodating the induction heating coil, and is arranged so that its central axis is substantially concentric with the induction heating coil. 4. The induction heating cooker according to claim 1, wherein the metal body is composed of a single wire or a plurality of wires. 5. The induction heating cooker according to claim 1, wherein the metal body is composed of twisted wires insulated from each other. 6. The induction heating cooker according to claim 1, wherein the metal body is arranged on a mounting surface on which the object to be heated is mounted.