JPH0670194U - Electromagnetic cooker - Google Patents

Abstract

(57) [Summary] [Purpose] The object of the present invention is to cook rice deliciously by uniformly heating the heating container even when cooking rice, which becomes sticky when heated and difficult to convection. In an electromagnetic cooker in which a heating container 1 is provided at an upper portion of the heating coil 1 facing the heating coil 3 for electromagnetic induction heating, the heating container 1 is made of a non-magnetic material such as aluminum alloy that is lightweight and has good heat conduction. It is assumed that the bottom surface has a self-temperature control function by spraying ceramic powder made of a magnetic material having a Curie point of about 200 ° C. and has a self-temperature control function. The heating layer 2 has a thin portion corresponding to an intermediate portion of the heating coil 3. The portion corresponding to the end portion of the heating coil 3 is formed thick, the temperature distribution of the entire bottom portion of the heating container 1 is uniform, a temperature detecting means or the like is not required, and an abnormal temperature rise is prevented.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an electromagnetic cooker, such as a commercial rice cooker, which improves the temperature distribution of a heated object.

[0002]

[Prior art]

 Conventionally, the iron holo type heating container that is electromagnetic induction heated is widely used as the heating container provided above the heating coil that performs electromagnetic induction heating, but it is used as a commercial rice cooker etc. Has a drawback that it is too heavy and difficult to use, and when an iron heating container is used, uneven temperature tends to occur and it is a problem for delicious cooking.

Therefore, the heating container is formed of a clad steel plate having an outer surface made of a magnetic material and an inner surface made of aluminum or the like which is lightweight and has good heat conductivity, and the temperature of the heating container is formed on the bottom of a protective frame constituting the heating container housing. An invention has been made to construct a sensor unit for detecting rice and cook rice. Also, the heating container is made of a lightweight non-magnetic material such as aluminum alloy, and the bottom of the heating container that opposes the heating coil is made of a room temperature magnetic material having a predetermined Curie temperature. However, when the temperature of the heating container reaches the Curie temperature or higher, the normal temperature magnetic material becomes non-magnetic, which reduces the induction heating of the heating container from the heating coil, and when the temperature of the heating container becomes lower than the Curie temperature, the normal temperature decreases. In some cases, the magnetic material becomes magnetic again and the heating container is induction heated. (See JP-A-4-220990)

[0004]

[Problems to be solved by the device]

 The iron heating container has the drawback that it is too heavy to be used as a commercial rice cooker and is difficult to use, and it tends to cause uneven heating, which is a problem for delicious cooking, and partially abnormal. There was a problem such as the generation of temperature.

The outer surface is made of a magnetic material and the inner surface is made of a clad steel plate made of aluminum or the like which is lightweight and has good thermal conductivity, and the sensor part for detecting the temperature of the heating container is formed at the bottom of the protective frame. Since it is easy to use, abnormal temperature rise is prevented, temperature unevenness is slightly reduced, and even when there is some temperature unevenness in the heating container when boiling or boiling normal water, the convection of the hot water makes the temperature uniform. However, when cooking rice, it gradually becomes sticky and becomes difficult to convection, but there is no consideration such as a configuration to make the magnetic flux density from the heating coil uniform, and there is uneven temperature in the heating container, and rice for commercial use is cooked. When it is used as a bowl, uneven heating is likely to occur and it is a problem to cook delicious rice.

[0006] The bottom of the heating container, which opposes the heating coil, is made of a room temperature magnetic material having a predetermined Curie temperature. Also becomes uniform and prevents an abnormal temperature rise, but there is a tendency that the temperature corresponding to the middle part of the heating coil still has a high magnetic flux density.

[0007]

[Means for Solving the Problems]

 The present invention has been made to solve the above problems, and a heating container is provided in the upper part of the heating coil, which is opposed to the heating coil for electromagnetic induction heating, and the heating container is made of a lightweight non-magnetic material such as aluminum alloy. A ceramic powder made of a magnetic material such as ferrite having a predetermined Curie temperature (eg, Curie point of about 200 ° C.) is sprayed on the outer bottom surface or the outer bottom surface and the side surface of the heating container to form a heat generating layer. The heat generating layer is thin at the part corresponding to the middle part of the heating coil and thick at the part corresponding to the end part of the heating coil.

[0008]

[Action]

 According to the configuration of the present invention, the heat-generating layer made of a magnetic material having a predetermined Curie temperature causes an eddy current to flow due to the magnetic flux emitted from the heating coil at a temperature lower than the predetermined Curie temperature (for example, about 200 ° C.) to generate heat. However, when the temperature reaches a certain Curie temperature, the magnetism decreases, making it less likely to be affected by the electromagnetic field and not generating heat, preventing abnormal temperature rise. In addition, the heating layer has a thin portion corresponding to the middle portion of the heating coil where the magnetic flux density is high and the temperature tends to rise, and a thick portion corresponding to the heating coil end portion where the magnetic flux density is low and the temperature is low. The temperature distribution on the entire bottom surface can be made uniform.

[0009]

【Example】

 An embodiment of the present invention will be described in detail below with reference to the drawings. 1 is a sectional view of an essential part of an electromagnetic cooker according to an embodiment of the present invention, FIG. 2 is a sectional view of an essential part of an electromagnetic cooker according to another embodiment of the present invention, and FIG. 3 is a temperature of ferrite. It is a characteristic diagram.

In FIG. 1, reference numeral 1 denotes a heating container made of a non-magnetic material such as an aluminum alloy which is lightweight and has good heat conductivity. A heating layer 2 made of a magnetic material is formed on the bottom surface of the heating container 1 by thermal spraying or the like. There is. The aluminum heating container 1 does not heat with a high frequency current of 25 kHz, but the heat generating layer 2 is usually made of ferrite or the like whose magnetic permeability sharply decreases at a temperature of around 200 ° C so that it can be heated with a high frequency current of 25 kHz. A ceramic magnetic material is used so that it does not absorb high-frequency current and does not generate heat at temperatures above 200 ° C. (Refer to FIG. 3) Reference numeral 3 is a heating coil which is tightly wound with a litz wire and is heated by electromagnetic induction, and 4 is a support plate which is provided with ferrite on its back surface so as to prevent leakage magnetic flux. Reference numeral 5 denotes a plate on which the heating container 1 is placed, which is made of heat-resistant glass ceramics or plastics that keeps the distance between the heating container 1 and the heating coil 3 constant and does not generate an eddy current.

Further, in the heat generating layer 2, the magnetic flux density increases in the middle portion of the heating coil 3 and the temperature rise of the heating container 1 tends to increase. Therefore, the thickness of the heat generating layer in the middle portion is formed thin so that the temperature does not rise. The thickness of the layer is set to about 0.1 mm, which is about half that of the end portion where the magnetic flux density is small.

Next, the operation of the above configuration will be described.

The heating container 1 made of a material having a good heat conductivity such as an aluminum alloy is light in weight and easy to handle, and the heating layer 2 made of a magnetic material having a predetermined Curie temperature has a temperature of about 200 ° C. at the start-up. Until the Curie temperature is reached, eddy current flows due to the magnetic flux radiated from the heating coil 3 and heats at maximum output. When the Curie temperature rises above 200 ° C, the magnetism decreases and it is less susceptible to the electromagnetic field and does not generate heat. At the same time, since it is induction heating, it has a small heat capacity, so that the heating container 1 does not overshoot the temperature and prevents an abnormal temperature rise.

Further, the portion corresponding to the middle portion of the heating coil 3 where the magnetic flux density is high and the temperature tends to be high is thin, and the portion corresponding to the end portion of the heating coil 3 where the magnetic flux density is low and the temperature is low is thick. The layer 2 can make the temperature distribution of the entire bottom surface of the heating container 1 having good heat conduction uniform.

It should be noted that, as shown in FIG. 2, when the heating layer 2 is provided on the bottom surface and side surfaces and the heating coil 3 is also provided on the bottom surface and side surface facing the heating layer 2, the same operational effect is obtained.

[0016]

[Effect of device]

 The present invention uses a ceramic powder made of ferrite or the like having a Curie point of about 200 ° C. on the outer bottom surface of the heating container or the outer bottom surface and the side surface of the heating container, which is made of a material such as an aluminum alloy that is lightweight and has good heat conduction, in the heating coil middle portion. Since the corresponding part is thin and the part corresponding to the edge is thickly sprayed to form the heat generating layer, the container can be made lighter and easier to handle, and the temperature distribution of the entire bottom of the heating container with good heat conduction is good. Even when cooking rice, which becomes uniform, becomes sticky when heated, and becomes difficult to convection, delicious cooking can be performed, and since it has a self-temperature control function, it does not require temperature detection means, etc., and has the effect of preventing abnormal temperature rise. .

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an electromagnetic cooker showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an essential part of an electromagnetic cooker showing another embodiment of the present invention.

FIG. 3 is a temperature characteristic diagram of ferrite.

[Explanation of symbols]

 1 heating container 2 heating layer 3 heating coil

Claims (2)

[Scope of utility model registration request] 1. An electromagnetic cooker provided with a heating container (1) in the upper part facing a heating coil (3) for electromagnetic induction heating, wherein the heating container (1) is made of a lightweight material such as an aluminum alloy and has a thermal conductivity. A heat generating layer (2) is formed by spraying a ceramic powder made of a normal temperature magnetic material having a predetermined Curie temperature on the outer bottom surface of the heating container (1). ) Is an electromagnetic cooker characterized in that the portion corresponding to the middle portion of the heating coil (3) is thin and the portion corresponding to the end portion of the heating coil (3) is thick. 2. A heating layer (2) is formed by spraying ceramic powder of a room temperature magnetic material having a predetermined Curie temperature on the outer bottom surface and side surfaces of the heating container (1).
Induction cooker described.