JPH11276341A - Electromagnetic induction heating rice cooker - Google Patents

Abstract

(57) [Problem] To prevent a step from being produced at the boundary between a magnetic metal material formed by thermal spraying from the outer bottom portion of the inner pot to the corners and side surfaces and the inner pot main body, Improves rust prevention performance. SOLUTION: An inner pot body 1a of an inner pot 1 is formed of a non-magnetic metal such as aluminum, and a magnetic metal material 1b such as iron is sprayed on an outer surface of the inner pot body 1a. Make the bottom part facing the electromagnetic induction coil the thickest,
Form gradually thinner from the corner to the side,
Further, the magnetic metal material 1b is placed on the magnetic metal material 1b.
The rust prevention layer 1d was provided in a wider range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rice cooker for cooking rice by generating heat in an inner pot by electromagnetic induction heating, and more particularly, to spraying a magnetic metal material onto the outer surface of an inner pot body made of a non-magnetic metal material. The present invention relates to an electromagnetic induction heating type rice cooker.

[0002]

2. Description of the Related Art Conventional electromagnetic induction heating type rice cookers are known in which an inner pot is formed by pressing a clad material in which an aluminum plate as a non-magnetic metal material and a stainless steel plate as a magnetic metal material are pressed. A stainless steel plate, which is a magnetic metal material, is spread on the bottom of a pan-shaped receiving mold, and molten aluminum, which is a non-magnetic metal material, is poured on top of it. In addition, there has been a method in which a magnetic metal material such as iron is thermally sprayed on an outer surface of an aluminum inner pan formed by pressing or melt forging.

[0003] Among these methods, the first one has a drawback that the magnetic metal material is limited to a stainless steel plate, iron which is a strong magnetic material cannot be used, and thus the heat generation efficiency is poor. Since the whole is composed of an aluminum plate and a stainless steel plate having a uniform thickness, there is a disadvantage that the aluminum plate and the stainless steel plate are apt to be peeled off when they are heavy and are processed into a complicated pot shape.
In addition, the following high-pressure melt forging has the disadvantage that the production cost is so large that it cannot be provided to consumers inexpensively, and the stainless steel plate, which is the heating element, has a uniform thickness, so the electromagnetic induction heating coil has In addition, the thickness of the heating element cannot be varied to adjust the heat generation balance. Further, since the inner pan is formed by pressing the molten aluminum at a high pressure with a pressing die, the pot itself cannot be manufactured unless it has a certain thickness, and there is a disadvantage that the inner pan becomes inevitably heavy.

[0004] On the other hand, in the case of spraying a magnetic metal material on the inner pan of a non-magnetic metal material shown last, a ferromagnetic material such as iron can be used as a heating element for induction heating. Since the magnetic metal material can be sprayed only on the parts required for induction heating, the inner pan does not become unnecessarily heavy, and the thickness of the spray can be varied according to the magnetic field generation condition (shape of the electromagnetic induction heating coil) In addition, there is an advantage that the heat generation balance can be adjusted.

Japanese Patent No. 2705083 discloses an electromagnetic induction heating type rice cooker using an inner pot of this thermal spraying system, and discloses a rice cooker which is not a rice cooker but is used as a pan for an electromagnetic induction heating cooker. JP-A-60-35491, JP-A-61-176089, JP-A-62-69481 and the like are already known.

[0006] However, those described above still cannot sufficiently exhibit the above-mentioned advantages, and have the following problems.

[0007]

That is, in the above-mentioned prior art, the thickness of the magnetic metal material is uniform except for those disclosed in JP-A-62-69481. For this reason, it is good to form the magnetic metal material layer on the entire outer surface of the inner pan, but when forming the magnetic metal material layer only on the portion facing the electromagnetic induction heating coil, the magnetic metal material layer is formed on the outer surface of the inner pan. There is a problem that a boundary portion is generated due to the presence or absence of the gap, and a step is generated at the boundary portion. Since the magnetic metal material needs a certain thickness (about 1.5 mm in Japanese Patent No. 2705083) to perform electromagnetic induction heating, the step at the boundary is large.

Further, it is necessary to provide a rust-preventive layer on the magnetic metal material layer in a wider range than the magnetic metal material layer for the purpose of rust prevention. In addition, there is a problem that the rust prevention layer is liable to be worn at a step portion with use, and the step at the end face of the magnetic metal material layer is exposed to cause rust.

Japanese Patent Application Laid-Open No. Sho 62-69481 differs in that the thickness of the magnetic metal material is partially varied. The purpose of the method is to eliminate uneven heating caused by electromagnetic induction heating. The thickness on the surface facing the heating coil is variable, and there is no intention to solve the problem of eliminating the step and maintaining the rust prevention performance.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to further improve the above-mentioned thermal spraying method, and the magnetic metal material formed by thermal spraying has the thickest bottom portion facing the electromagnetic induction heating coil. By gradually reducing the thickness from the corners to the side surfaces, the boundary with the magnetic metal material is formed without any step. As a result, the rust preventive layer formed on the magnetic metal material is formed on a smooth boundary with no edge of the step and fixed in a stable state, and the rust preventive layer is cut off at the edge of the step or used. At the same time, the rust preventive layer does not peel off, and high rust preventive performance can be maintained.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention has an inner pot and an electromagnetic induction heating coil for generating heat in the inner pot. The inner pot body is formed of a non-magnetic metal material. In a rice cooker obtained by spraying a magnetic metal material, the thickness of the sprayed magnetic metal material is increased at the bottom portion facing the electromagnetic induction heating coil, and gradually reduced from the corner portion to the side surface. The outer surface of the metal material is covered with a wider range of anti-rust layer.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a cross-sectional view of a rice cooker according to the present invention in the front-rear direction, and FIG. 2 is an enlarged view of a bottom portion of an inner pot of the rice cooker, showing a change in the thickness of a sprayed portion.

In the figure, 1 is an inner pot, 2 is a main body, 3 is a lid, 4 is a protective frame, 5 is an electromagnetic induction heating coil, 6 is a temperature sensor,
7 is a control part, 8 is a magnetic shielding material, 1a is an inner pot main body, 1b is a magnetic metal material, 1c boundary part, 1d is a rust prevention layer, and 1e is a fluororesin layer.

More specifically, the inner pan 1 is housed in the main body 2 so as to be detachable, and a lid 3 is attached to the main body 2 so as to be openable and closable, and the upper openings of the inner pan 1 and the main body 2 are closed. doing. A protective frame 4 is provided inside the main body 2,
An electromagnetic induction heating coil 5 is provided at the bottom of the protection frame 4. The electromagnetic induction heating coil 5 is formed by winding an electric wire a plurality of times in the circumferential direction, and does not exist at or near the center of the bottom of the inner pan 1, but from near the middle of the bottom radius of the inner pan 1 to the bottom corner. The inner pan 1 is integrally provided in a flat plate shape up to a point farther from the electromagnetic induction heating coil 5, that is, in the vicinity of the diameter of the upper end of the inner pan 1. A temperature sensor 6 is provided at the center of the bottom of the protective frame 4 and is in contact with the bottom of the inner pot 1.

A control section 7 for generating a high-frequency magnetic field in the electromagnetic induction heating coil 5 is provided in the main body 2, and a temperature sensor 6 is also connected to the control section 7 so as to generate electric power determined based on temperature information. The current supply to the electromagnetic induction heating coil 5 is controlled.

A magnetic shield 8 is provided on the lower surface of the electromagnetic induction heating coil 5 to absorb the lower magnetic field of the high frequency magnetic field generated from the electromagnetic induction heating coil 5 up and down. It occurs only on a certain upper side.

The inner pan 1 is made of aluminum, which is a high heat conductive material, is formed into a pan shape by a press or a molten metal forging method, and is subjected to a roughening process on an outer surface to increase a thermal spray adhesion. And a magnetic metal material 1b such as iron formed on the bottom by thermal spraying.
b indicates that the bottom surface facing the electromagnetic induction heating coil 5 has a thickness of 0.
The inner pot 1 is formed to have a thickness of about 7 mm, and is gradually thinned from the corner to the side of the inner pot 1 so that the thickness becomes zero at the boundary 1c. Thermal spraying is a method in which the magnetic metal material is melted and sprayed into the inner pot main body 1a at high pressure in the form of fine particles and adhered to each other. doing. Therefore, the thickness can be easily varied as described above by adjusting the range to be sprayed and the time for spraying (generally, adjusting the program of the movement of the robot arm).

Since the sprayed surface of the magnetic metal material 1b has a file shape due to lamination of fine particles, the surface is polished to smooth the surface, and then the magnetic metal material 1b is polished.
A rust prevention layer 1d is formed on the surface by thermal spraying.

The rust prevention layer 1d is formed of a material such as zinc or aluminum for the purpose of preventing rust of the magnetic metal material 1b.
The thickness is approximately 0.05 mm approximately uniformly. The range is provided above the boundary 1c.
Has been applied to completely cover. Further, the entire outer surface of the inner pot 1 is covered with a fluorine resin layer 1e from above.

In the method in which the thickness of the magnetic metal material 1b is not gradually reduced toward the boundary 1c as in the present invention, a step is formed in the boundary 1c as in the prior art, and the rust prevention layer 1d
The rust prevention layer 1d at the edge of the step is interrupted even if it is formed, or even if it can be formed without interruption, the rust prevention layer 1d at the edge is worn away with use, and the magnetic metal material layer 1b is exposed to generate rust. Will be.

On the other hand, in the present invention, the boundary 1
Since c has no steps or edges, the rust-preventive layer 1d can be formed smoothly, and the fluororesin layer 1e can be formed smoothly similarly. As a result, the rust preventive layer 1d that generates rust does not wear.

The magnetic metal material 1b becomes thinner from the corner of the inner pot 1 to the side boundary 1c. However, the magnetic metal material 1b gradually moves away from the electromagnetic induction heating coil 5 and the heating is weakened. Absent.

[0024]

As described above, according to the present invention, an inner pot is formed from a non-magnetic metal material, and the outer surface of the inner pot is sprayed with a magnetic metal material. The opposite bottom is made thicker, formed gradually thinner from the corner to the side, and a rust prevention layer covering the magnetic metal material in a wider area than the magnetic metal material layer is provided on this magnetic metal material, so that the inner pot and The boundary between the magnetic metal materials can be formed without a distinct step between the magnetic metal materials.

Further, the rust prevention layer formed on the magnetic metal material layer is formed on a smooth boundary portion having no step edge, so that it can be fixed in a stable state, and the rust prevention layer is formed at the step edge. The rust prevention layer does not break off with use and the rust prevention layer does not peel off with use, and high rust prevention performance can be maintained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a rice cooker according to the present invention in a front-rear direction.

FIG. 2 is an enlarged bottom view of an inner pot of the rice cooker.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner pot 1a Inner pot main body 1b Magnetic metal material 1c Boundary part 1d Rust prevention layer 1e Fluororesin layer 2 Main body 3 Lid 5 Electromagnetic induction heating coil

Claims (1)

[Claims] 1. An inner pot (1) in a main body (2) and an electromagnetic induction heating coil (5) for generating heat in the inner pot (1).
A rice cooker in which an inner pot body (1a) constituting the inner pot (1) is formed of a non-magnetic metal material and a magnetic metal material (1b) is thermally sprayed on an outer surface of the inner pot body (1a), The thickness of the magnetic metal material (1b) sprayed is increased at the bottom portion facing the electromagnetic induction heating coil (5) and gradually reduced from the corners to the side surfaces. Cover the side with a wider area of rust prevention layer (1
An electromagnetic induction heating rice cooker characterized by being covered with d).