JPH0622953Y2 - Induction heating cooker - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application The present invention relates to a cooking tool such as a pan or a frying pan heated by an induction heating cooker.

(B) Conventional Technology An induction heating cooker is a device for induction-heating a metallic cooking utensil disposed in the vicinity of a heating coil by applying a high-frequency current to a flat heating coil to generate a high-frequency alternating magnetic field. In such an induction heating cooker, a large amount of magnetic flux is supplied to the bottom surface of the cooking utensil in the donut-shaped portion facing the heating coil, a large amount of heat is generated at that portion, and little heat is generated at other portions. Like For this reason, there has been a structure in which a good material having good thermal conductivity is attached to the inside as in Japanese Utility Model Laid-Open No. 61-2490.

(C) Problems to be Solved by the Invention By the way, in the above-described conventional cooking utensils, heat is diffused through a material having good thermal conductivity, but the heat pattern on the bottom surface of the cooking utensils is not improved. That is, the magnetic flux passing through the bottom surface of the cooking utensil is radially formed outward from the bottom surface portion corresponding to the inner peripheral portion of the heating coil. Therefore, the heat generated on the bottom surface of the cooking utensil gradually decreases from the bottom surface portion corresponding to the inner peripheral portion of the heating coil toward the outer periphery. Therefore, the temperature of the bottom surface varies depending on the nonuniformity of heat generation.

(D) Means for Solving the Problems The present invention has been made in view of such a point, in which a conductive magnetic material is provided on the bottom surface, and the layer thickness of the conductive magnetic material is reduced. The cooking utensil is gradually thinned toward the outer periphery.

(E) Action By arranging the cooking utensil immediately above the heating coil, the magnetic flux emitted from the heating coil will pass radially outward from the center through the conductive magnetic material at the bottom of the cooking utensil.
In the present invention, since the conductive magnetic material at the bottom of the cooking utensil changes so that the layer thickness thereof gradually decreases toward the outer peripheral direction, the magnetic flux density does not change much at the inner peripheral portion of the bottom surface and the outer peripheral portion of the bottom surface. Since the magnetic flux density 1B and the potential amount 1A (vector potential) have a relation of 1B = rot1A,
Energy absorbed by the cooking utensil, that is, the amount of heat generated, is made uniform from the inner peripheral portion of the bottom surface to the outer peripheral portion thereof.

(F) Example FIG. 1 is a cross-sectional view when heating the induction cooking utensil of the present invention, and FIG. 2 is a diagram showing changes in the magnetic flux density of the magnetic flux passing through the bottom surface of the cooking utensil. In these drawings, (1) shows an induction heating coil having an inner circumference of 46 mm and an outer circumference of 172 mm, and (2) shows a ceramic top plate provided on the induction heating coil (1). (1) The distance from the top surface to the top plate (2) is adjusted to 9.5 mm. (3) is a cooking pot made of a material having a high thermal conductivity such as stainless steel, copper, or aluminum having a bottom diameter of 200 mm, and a conductive magnetic material having a high magnetic susceptibility (4) such as iron on the bottom. Are provided in layers. Then, as shown in the figure, the magnetic material (4) is changed so that the layer thickness is gradually reduced from the center of the bottom of the pan of the coil (1) toward the outer periphery.

When a high frequency magnetic field is generated from the heating coil (1) in such a state, the magnetic flux density at the inner circumference of the cooking pot (3) and the magnetic flux density at the outer circumference of the cooking pot (3) are uniform as shown by the solid line in Fig. 2. Be converted.
Here, the dotted line is the characteristic of the magnetic flux density when the thickness of the magnetic material (4) on the back surface of the cooking pot (3) is made uniform.

In addition, when the setting of the magnetic material (4) is changed below the skin depth determined by the magnetic flux frequency supplied from the heating coil (1), the substantial resistance of the magnetic material (4) increases toward the outer peripheral direction. It becomes easier to be heated.

Further, although metal such as stainless steel and copper is used as the cooking pot (3), it may be a casting or a ceramic.

FIG. 3 shows a sectional view of an induction heating cooker according to another embodiment of the present invention when induction heating is performed. The same parts as those in FIG. 1 are designated by the same reference numerals. In the figure, the difference from FIG. 1 lies in that the thickness of the magnetic material (4) at the center of the heating coil (1), that is, the bottom of the cooking pot corresponding to the inner side of the heating coil (1) is made thinner. . This also improves the heating of the center of the bottom of the pan (3).

(G) Effect of the Invention As described above, the induction heating cooker of the present invention is provided with the conductive magnetic material on the bottom surface, and the layer thickness of the conductive magnetic material is gradually increased from the central portion of the cookware toward the outer peripheral portion. Since it is changed to be thin, the magnetic flux density in the magnetic material does not change so much whether it is inside or outside the bottom surface of the cooking utensil.
A calorific value is made uniform, and a cooking tool which is easy to cook is provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of heating the induction heating cooker of the present invention, and FIG. 2 is a diagram showing the magnetic flux density of a magnetic material provided on the bottom surface when the cooker of the present invention is used, FIG. FIG. 4 is a cross-sectional view when heating an induction heating cooker according to another embodiment of the present invention. (1) …… Heating carp, (2) …… Ceramic top plate, (3) …… Cooking pot, (4) …… Conductive magnetic material.

Claims (1)

[Scope of utility model registration request] 1. An induction heating cooker which is induction-heated by applying an alternating magnetic field, wherein a conductive magnetic material is formed such that the layer thickness is gradually reduced from near the center of the cookware toward the outer periphery. A cooking utensil for induction heating having a bottom surface.