JPS5848799Y2 - High frequency heating device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a coaxial line of a high frequency heating device using a magnetron or the like.

Microwave ovens using magnetrons are widely used for heating, cooking, and defrosting foods.

This microwave oven has a structure that radiates microwave energy oscillated by a magnetron into a heating chamber, but due to design constraints, there is a gap between the magnetron, which is a high-frequency oscillator, and the antenna of the heating chamber that radiates microwave energy. may become separated.

In such a case, it is necessary to connect the magnetron and the antenna of the heating chamber with a coaxial line that transmits microwave energy.

FIG. 1 shows a sectional view of an example of such a conventional microwave oven.

A magnetron 2 and a heating chamber 3 are housed in a cabinet 1 of the microwave oven.

The heating chamber 3 is surrounded by a wall 4, and the front side is a door 6 through which heated food 5 is taken in and taken out.

An antenna 7 is provided on the upper surface of the heating chamber 3, and the magnetron 2 and the antenna 7 are connected by a coaxial line 8.

The coaxial line 8 consists of a cylindrical outer conductor 9 and an inner conductor 10 extending to the center thereof.

The microwave energy oscillated by the magnetron 2 is transmitted through a coaxial line 8 and supplied to an antenna 7, from which it is radiated into the heating chamber 3.

Here, the outer conductor 9 of the coaxial line 8 is made of a metal tube with good conductivity such as copper or aluminum, and the inner conductor 10 is similarly made of a rod or thin tube made of copper or aluminum, but these are generally It's expensive.

Furthermore, the curved portion of the coaxial line 8 has a complicated structure, which makes it even more expensive.

FIG. 2 shows a detailed cross-sectional view of the coaxial line 8 at a right angle. The outer conductors 9 are connected to each other at right angles by a joint conductor 11, and the joints are in complete electrical contact. Each is tightened with a band 12.

Further, the inner conductor 10 has one end formed into a flat plate shape, and the other end is screwed to connect them in a perpendicular direction with a screw 13.

A lid 14 is provided at one end of the joint conductor 11, and the lid 14 is removed and a screw 13 is screwed into the joint conductor 11.

Note that 15 is an insulator for supporting the inner conductor 10 on the outer conductor 9.

In order to bend the coaxial line 8 at right angles in this way, the joint conductor 11. Band 12, screw 13. A large number of parts such as the lid 14 are required, which increases material costs and requires additional assembly man-hours, which increases costs.

The present invention was conceived with these points in mind, and its purpose is to form the inner conductor into a plate shape, extend a support piece from it to a length of 1/4 wavelength, and then form the outer conductor. An object of the present invention is to provide a high-frequency heating device that is inexpensive and has little radio wave leakage by fixing the radio wave to the radio wave.

The details of the present invention will be explained below using examples. FIG. 3 is a cross-sectional view of an embodiment of the high-frequency heating device according to the present invention, and FIG. 4 is a partially cutaway perspective view of the coaxial line thereof.

In the figure, parts that are the same as those shown in FIG. 1 are given the same numbers.

The output part of the magnetron 2 as a high frequency oscillator and the antenna 7 of the heating chamber 3 are connected by a coaxial line 16, and the outer conductor 17 is a U-shaped outer conductor formed only on the outside and side surface. Piece 17 a and wall 4 of heating chamber 3 located inside
It is composed of.

The inner conductor 18 is made by pressing a metal plate of copper or aluminum, and is formed to extend in a band shape along the line.

A support piece 1 is installed in a direction perpendicular to the direction in which the line extends from the inner conductor 18.
9 is formed, and its tip is bent to form a joint 20. This joint 20 is welded to the side wall surface of the outer conductor piece 17a, and the inner conductor 18 is supported on the outer conductor 17.

The supporting piece 19 and the joint portion 20 are formed at the same time when the inner conductor 18 is formed by press working.

Further, the length of the support piece 19 is set to be 1/4 of the wavelength of the microwave oscillated by the magnetron 2 and transmitted through the coaxial line 16.

Therefore, from the inner conductor 18 portion of the support piece 19 to the outer conductor 1
The impedance seen in the direction of 7 becomes very large and can be considered equivalent to an open state for microwaves.

Therefore, even though the inner conductor 18 is directly connected to the outer conductor 17 via the support piece 19, microwaves are transmitted between the inner conductor 18 and the outer conductor 17 in the same way as in a normal coaxial line.

That is, the outer conductor 17 is commonly used as an outer conductor for the inner conductor 18 and the support piece 19, and the microwave of the fundamental wave oscillated in the magnetron 2 is generated when the length of the support piece 19 is 1/4 of the wavelength. Because of the shape of the wave, it is reflected at the end of the support piece 19, but microwaves other than the fundamental wave are out of phase and attenuated.

Therefore, as mentioned above, the coaxial line 16 transmits energy without attenuation to the microwave of the fundamental wave oscillated by the magnetron 2, and a strong fundamental radio wave is radiated from the antenna 7. Inner conductor 18 and outer conductor 1 are used for unnecessary microwaves such as second high frequency and sideband.
7 and the supporting piece 19 connecting therebetween are bands, paths,
Since they act as a filter, they are greatly attenuated and are not transmitted to the antenna 7.

In this way, the inner conductor 18 can be easily manufactured from a plate material by pressing, etc., and can be easily attached to the outer conductor 17 via the support piece 19, so that the coaxial line 16 can be manufactured at low cost.

Furthermore, the structure for bending the coaxial line 16 at right angles can be easily formed by simply bending the band of the inner conductor 18 at right angles, without using any complicated mechanism as in the prior art.

Furthermore, the support piece 19 also serves as a filter, and leakage of unnecessary radio waves can be greatly attenuated.

Further, in this embodiment, since the wall surface of the heating chamber is used as a part of the outer conductor, materials can be saved and assembly can be facilitated.

FIG. 5 shows a cross-sectional view of a coaxial line in another embodiment,
The same parts as in FIG. 4 are given the same numbers.

The outer conductor 17b is formed in an L-shape, and constitutes the outer conductor using a corner formed by the wall 4 of the heating chamber and a part of the inner wall 21 of the cabinet.

Less material is used for the outer conductor piece 17b, further reducing costs.

Moreover, FIG. 6 shows a perspective view of the inner conductor 18a of the coaxial line of another embodiment, and shows support pieces 19a, 19b, 19.
This is an example in which C and the like are formed at predetermined locations in a direction perpendicular to the surface of the inner conductor 18a.

In this case, it goes without saying that the supporting pieces 19 a , 19 b , and 19 C are formed to have a length that is 1/4 of the wavelength of the fundamental wave.

As described above, according to the high-frequency heating device of the present invention, in the high-frequency heating device configured to guide microwave energy oscillated by a high-frequency oscillation device to a heating chamber through a coaxial line, the inner conductor of the coaxial line is connected to a metal plate. A supporting piece having a length of 1/4 of the wavelength of the oscillated high frequency wave from the inner conductor is integrally provided in a direction perpendicular to the extending direction of the inner conductor, and the tip of the supporting piece is connected to the outer conductor of the coaxial line. By fixing it to the base, the structure is simple and inexpensive, and has the effect of reducing leakage of unnecessary radio waves.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional microwave oven, Fig. 2 is a sectional view of a right angle part of its coaxial line, Fig. 3 is a sectional view of an embodiment of the high frequency heating device of the present invention, and Fig. 4 is a sectional view of its coaxial line. A partially cutaway perspective view of the line, FIG. 5 is a sectional view of a coaxial line of another embodiment,
FIG. 6 is a perspective view of the inner conductor of another embodiment.

Claims (1)

[Scope of utility model registration request] 1. In a high-frequency heating device configured to guide microwave energy oscillated by a high-frequency oscillator to a heating chamber through a coaxial line, the inner conductor of the coaxial line is formed of a metal plate, A high-frequency heating device characterized in that a support piece formed to have a length of /4 is integrally provided in a direction perpendicular to the extending direction of the inner conductor, and a tip of the support piece is fixed to the outer conductor of the coaxial line. 2. The high-frequency heating device according to claim 1, wherein a wall surface of the heating chamber is used as a part of the outer conductor.