JPH06196257A - Microwave oven - Google Patents

Abstract

PURPOSE:To uniformly and efficiently raise the temperature of an object to be heated by microwaves by forming both or either one of the bottom face and ceiling of a cooking chamber into a spherical shape with a metal plate. CONSTITUTION:The microwaves guided into the cooking chamber 1 of a microwave oven from a wave guide 3 through a feed port are radiated to an object 8 to be heated while being repeatedly reflected and refracted on the wall face of the cooking chamber 1. The attenuation of the microwave power is small if the repetitions of the reflection and refraction are reduced. When both or either one of the bottom face 7a and ceiling face 6a of the cooking chamber 1 is formed into a sphere, the repetitions of the reflection and refraction occurring until the microwaves are radiated to the object 8 are reduced, the heating efficiency can be increased, and the degree of heating irregularities is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave oven in which the shape of a cooking chamber is changed so that the temperature of an object to be heated by microwaves rises substantially uniformly and efficiently.

[0002]

2. Description of the Related Art A schematic sectional view of a conventional microwave oven is shown in FIG. In the figure, 1 is a cooking chamber, 2 is a magnetron as a microwave source, 3 is a waveguide, 4 is a stub, 5 is a turntable, 6 is a ceiling surface, 7 is a bottom surface, 8 is a food to be heated,
9 is a power supply unit. The cooking chamber has a cubic shape made by bending and welding a metal plate as shown in the drawing. The microwave generated by the magnetron 2 is guided to the cooking chamber 1 through the waveguide 3. Usually, first, the impedance is adjusted to increase the microwave efficiency, but as one means therefor, the protruding length of the stub 4 protruding into the waveguide 3 is adjusted to adjust the impedance. On the other hand, since microwaves are diffused on the other hand, although not shown in this figure, metal rotating blades called a stirrer rotating in a horizontal plane are installed on the food 8 to be heated, or the food 8 is placed on the turntable 5. Place and rotate in a horizontal plane. The stirrer and turntable almost eliminate the uneven heating in the horizontal plane due to the non-uniformity of microwave irradiation. However, uneven heating in the vertical direction cannot be eliminated.

Conventionally, various methods have been taken to increase the efficiency of microwave ovens and improve uneven heating, but most of them have been improved by changing the impedance of each part against microwaves and microwave power generation sources. Improving by the number and position of the power feed ports that connect the microwave guide from the output part of the magnetron to the cooking chamber and the cooking chamber, or introducing cooling air with increased temperature after cooling the magnetron into the cooking chamber Met.

[0004] For example, in Japanese Patent Laid-Open No. 2-301989, a waveguide having a rectangular cross section arranged along the outside of the wall surface of the cooking chamber is provided with a plurality of power supply ports, including those at both ends, which communicate with the cooking chamber. Instead of installing a magnetron near the end of the waveguide that is terminated by a so-called back plunger as in the conventional case, attach a magnetron in the middle of the portion of the waveguide surface facing the feed opening facing the multiple feed openings. , It is disclosed that the manufacturing of the waveguide is facilitated and at the same time, the uneven heating is reduced by the plurality of power supply ports.

Further, Japanese Laid-Open Patent Publication No. 53-97751 discloses that the magnetron cooling air whose temperature has risen after cooling the magnetron is introduced into the cooking chamber to improve the heating efficiency.

[0006]

However, when a liquid is put into a deep cup and heated in a microwave oven in which two upper and lower power supply ports are provided on the side wall of the cooking chamber, the temperature distribution in the vertical direction is improved. Although it was observed, a considerable temperature difference was still observed. In addition, sending the cooling wind of the magnetron to the cooking chamber complicates the structure because it requires a duct in addition to the waveguide, and the efficiency does not necessarily increase as expected depending on the load condition, which is hygienic. There was a problem such as not being.

It is an object of the present invention to provide a microwave oven which does not have the above-mentioned problems and is capable of efficiently raising the temperature of a target object heated by microwaves substantially evenly. .

[0008]

In order to solve the above problems, in the present invention, both or either one of the bottom surface and the ceiling surface of the cooking chamber of the microwave oven is formed into a spherical shape with a metal plate.

[0009]

[Function] The microwave guided from the waveguide through the power supply port into the cooking chamber of the microwave oven is reflected on the wall surface of the cooking chamber,
The object to be heated, for example, food is irradiated while repeating refraction. Obviously, the smaller the number of repetitions of microwave reflection and refraction before the microwave irradiates the object to be heated, the smaller the microwave power attenuation. If the bottom surface and / or the ceiling surface of the cooking chamber of the microwave oven is made spherical, the reflection that the microwave receives until it irradiates the object to be heated,
Since the number of refraction is reduced, the heating efficiency is necessarily increased, and at the same time, the degree of uneven heating is reduced.

[0010]

1 is a schematic sectional view of an embodiment of the present invention.
In the figure, 6a is a ceiling surface formed of a metal plate according to the present invention in a spherical shape, 7a is a bottom surface formed of a metal plate according to the present invention in a spherical shape, and other reference numerals are the same as in the case of FIG. . The radius of curvature R of the spherical surface is determined so as to satisfy the following equation (1).

R ² ≧ (W / 2) ² + (H / 2) ² (1) where H: height of the cooking chamber W: width of the cooking chamber If this formula is not satisfied, the volume of the cooking chamber is It will be obvious from Fig. 3 that the amount is too small. The bottom surface and the ceiling surface are joined to the three side surfaces made of a metal plate by a method such as welding which is electrically connected as in the conventional case.

[0012]

As described above, according to the present invention, the efficiency of heating by microwave power is improved, the power consumption is suppressed, and the vertical temperature difference during heating is reduced. To be

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a conventional microwave oven.

FIG. 3 is a reference diagram for viewing a relationship between a radius of curvature R of a bottom surface and a ceiling surface of a microwave oven according to the present invention and a height H and a lateral width W of a cooking chamber.

[Explanation of Codes] 1 ... Cooking room, 2 ... Magnetron, 3 ... Waveguide, 4
... Stub, 5 ... Turntable, 6a ... Spherical ceiling surface according to the present invention, 7a ... Spherical bottom surface according to the present invention, 8 ... Food to be heated, 9 ... Power supply section.

Claims (1)

[Claims] 1. A microwave oven in which a bottom surface and / or a ceiling surface of a cooking chamber are formed of a metal plate into a spherical shape.