JPH0634387B2 - High frequency heating device - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a high frequency heating apparatus, and more particularly to improvement of a high frequency heating apparatus having a rectangular waveguide provided in a heating chamber.

[Technical background of the invention and its problems]

In a microwave oven (high frequency heating device), a rotary waveguide is installed in the heating chamber, and microwaves (high frequency) are radiated from the rotary waveguide into the heating chamber to effectively heat the food. There is something like this.

As such a microwave irradiation technique, the one shown in FIG. 7 has been used. That is, the excitation opening a is formed on the bottom wall.
A rectangular wave guide b having a rectangular shape is provided, and this is arranged on the upper side in the heating chamber c, and a magnetron d (oscillator) is provided.
In addition to receiving microwaves oscillated from the motor, a motor (driving device) in which the rotary waveguide b is arranged outside the heating chamber c
The structure connected to e was used, and the microwave was radiated into the heating chamber c from the excitation opening a rotating together with the rotating waveguide b. Note that f indicates a waveguide for guiding the microwave oscillated from the magnetron d to the rotary waveguide b.

By the way, the rotary waveguide b used for microwave irradiation
Conventionally, a metal plate is conventionally shaped so as to match the shape of the container, the shaped metal plate is assembled into a shape of the container, and then the corners are joined together by spot welding or the like. Alternatively, as shown in FIG. 9, the whole is configured like a vessel, but it has various problems.

That is, the process is complicated because a step of cutting the metal plate, assembling it into a container, and then joining the mating portions is required. Moreover, at the time of cutting, there is a problem that a material loss occurs and the rotary waveguide b becomes expensive in cost. In addition, there is a problem that the electric field tends to concentrate in the gap between the joints because of the joints. In particular, when such electric field concentration occurs, a spark is generated at that portion, which melts or deforms the rotary waveguide b, and there is a problem that the heating performance of the microwave oven deteriorates due to output loss due to the spark.

More specifically, the waveguide constituted by the main waveguide f and the rotating waveguide b guides the microwave output from the magnetron to the final excitation aperture without loss and irradiates it there from without loss. . However, in such a waveguide, a standing wave is formed and the electric field is likely to be concentrated at a certain place. In particular, since minute gaps inevitably occur at the above-mentioned junctions, electric field concentration occurs in the gaps at the junctions, sparks occur, and there is no waveguide loss structure from the magnetron to the final excitation aperture. However, an output loss occurs at the rotating waveguide b portion.

In addition, in FIG. 8 and FIG. 9, g shows a joint part, respectively.

[Object of the Invention]

The present invention has been made in view of such problems, and an object thereof is to provide an inexpensive high frequency heating apparatus having a rectangular waveguide in which no electric field is concentrated.

[Outline of Invention]

That is, the present invention is to eliminate the above-mentioned problems by forming a rectangular waveguide integrally into a container by drawing a metal plate.

Example of Invention

The present invention will be described below with reference to the first embodiment shown in FIGS. FIG. 3 shows a high-frequency heating apparatus to which the present invention is applied, for example, a microwave oven, 1 is a main body, 2 is a heating chamber arranged in the main body 1, and 3 is an excitation provided on an upper wall of the heating chamber 2. Apertures 4 are main waveguides having a magnetron 5 connected to one end side. The main waveguide 4 is arranged on the upper wall of the heating chamber 2, and the outlet side of the main waveguide 4 is connected to the opening 3 so as to supply the microwave (high frequency) oscillated from the magnetron 5 to the heating chamber 2. I am able to do so.

On the other hand, 6 is a rectangular waveguide. The structure of the rectangular waveguide 6 is shown in FIG. Here, the rectangular waveguide 6 will be described. This is a rectangular waveguide having a rectangular opening with a metal plate that is easy to plastically work, for example, an aluminum plate, drawn and drawn. The main body 6a is integrally formed. Then, a fixing hole 8 is provided on the bottom wall of the thus formed waveguide body 6a at a position eccentric from the center to one end side, and a rectangular excitation opening 9 is provided on the other end side opposite to this. Are provided along the width direction. The rectangular waveguide 6 has an opening with the opening 3
It is arranged on the upper side in the heating chamber 2 so as to face the above, and can receive the microwave emitted from the opening 3.

On the other hand, 10 is a motor (corresponding to the drive device of the present invention) installed on the outer surface of the upper wall of the main waveguide 4 and positioned directly above the opening 3. The tip of the shaft 10 a of the motor 10 extends through the main waveguide 4 to just below the opening 3.
Then, as shown in FIG. 2, the hole 8 of the rectangular waveguide 6 is fixed to the tip of the shaft 10a by using a fixing screw 11, so that the motor 12 can eccentrically rotate the rectangular waveguide 6. ing. Of course, it goes without saying that the opening of the rectangular waveguide 6 is sized to allow the entire opening 3.

The excitation opening 9 is located at a position deviating from directly below the opening 3. The rectangular waveguide 6 and the upper wall of the heating chamber 2 form a tubular portion. In FIG. 3, reference numeral 12 denotes a partition which is provided so as to cover the periphery of the rectangular waveguide 6 and which protects the rectangular waveguide 6 and which is made of a material having excellent radio wave permeability, such as a heat-resistant resin. It is a plate.

In the microwave oven configured in this manner, when the cooking object (object to be heated) 13 is housed in the heating chamber 2 and the operating portion of the microwave oven (not shown) is operated, the motor 10 is activated and the rectangular waveguide 6 is operated. Rotate. On the other hand, the microwave is oscillated from the magnetron 5 in accordance with the operation of the operation unit. Then, the oscillated microwave is guided to the main waveguide 4, the opening 3, and the rectangular waveguide 6 (cylindrical portion) as shown by the arrow in FIG. 3, and the excitation opening is rotated about the shaft 10a. The food (heated material) 13 is irradiated from 9 through the partition plate 12.

Here, it is pointed out that the conventional excitation structure using such a rotating waveguide has a high cost of the rotating waveguide and is prone to sparks.

However, according to the present invention, the rectangular waveguide 6 is integrally formed into a container shape by drawing a metal plate. This means that only one drawing process is required to process the rectangular waveguide 6, and at the same time, it is clear that the rectangular waveguide 6 has no junction that causes electric field concentration. That is, it can be seen that the rectangular waveguide 6 has a structure that is easily machined, has no material loss, and has no spark. Therefore, the cost can be reduced, and at the same time, problems such as melting, deformation, and output reduction can be eliminated. As a result, it is possible to provide an inexpensive microwave oven having the rectangular waveguide 6 that is highly reliable.

Not only the first embodiment described above, but also the second embodiment shown in FIG. 4, the third embodiment shown in FIG. 5, and the fourth embodiment shown in FIG. Good.

That is, as shown in FIG. 4, the outer peripheral end of the flange portion 6b formed at the opening edge of the rectangular waveguide 6 is formed in a curl shape. Such a structure has an advantage that the edge at the outer peripheral end of the flange portion 6b can be eliminated and the danger due to the edge at the time of assembly can be eliminated, and at the same time, the rigidity strength can be increased.

In addition, as shown in FIG. 5, the bottom wall portion of the rectangular waveguide 6 in which the fixing hole 8 is located is cut and raised in a substantially L shape, and the support portion 21 for connecting to the motor 10 is formed on the inner bottom surface. It is one that is projected. With such a structure, when the rectangular waveguide 6 is assembled, the head of the fixing screw 11 can be connected to the shaft 10a without projecting to the heating chamber 2 side. There is an advantage that the gap X between the partition plate 12 and the rectangular waveguide 6 can be reduced by the height of the head of the. That is, the height of the head of the fixing screw 11, the partition plate 12 and the mounting shelf 22 as shown in FIG.
It is possible to increase the height between the two, that is, the effective height A of the heating chamber 2. Moreover, such a supporting portion 20 not only expands the effective height A of the heating chamber 2, but also functions as a reflecting portion that diffusely reflects microwaves, and the opening 23 formed by cutting and raising also functions as an excitation opening. Therefore, there is an effect that the microwave can be uniformly and efficiently applied to the cooking object 13 in a random irradiation direction.

On the other hand, FIG. 6 shows a modification of the previous FIG. 5, in which the bottom wall portion of the rectangular waveguide 6 in which the fixing hole 8 is located is bulged into a trapezoidal shape, and the motor is attached to the inner bottom surface. A support portion 21 for connecting with 10 is integrally projected. Such a structure increases the effective height A of the heating chamber 2 described above and diffuses microwaves, and also increases the rigidity of the rectangular waveguide 6 to lower the heating performance of the microwave oven due to deformation. Has the advantage that it can be eliminated.

In FIGS. 4 to 6, the same components as those in the first embodiment described above are designated by the same reference numerals and the description thereof is omitted.

〔The invention's effect〕

As described above, according to the present invention, it is possible to provide a rectangular waveguide that has no junction that causes electric field concentration and has no material loss. Therefore, at low cost, the generation of sparks in the rectangular waveguide can be eliminated, melting and deformation can be prevented, and high frequency output loss is reduced,
It has excellent effects such as reduction of heating performance.
A high frequency heating device can be provided.

[Brief description of drawings]

1 to 3 show a first embodiment of the present invention,
FIG. 1 is a perspective view showing a rectangular waveguide, FIG. 2 is a front sectional view showing an installation structure of the rectangular waveguide, FIG. 3 is a front sectional view showing a high frequency heating device, and FIG. FIG. 5 is a side sectional view showing a different rectangular waveguide of the second embodiment, and FIG.
Is a front sectional view showing a different rectangular waveguide of the embodiment of FIG. 6, FIG. 6 is a front sectional view showing a different rectangular waveguide of the fourth embodiment of the present invention, and FIG. 7 is a conventional rotating waveguide. Front sectional views showing the adopted high-frequency heating device, and FIGS. 8 and 9 are perspective views showing the conventional different rotating waveguides. 2 ... Heating chamber, 3 ... Opening, 4 ... Main waveguide, 5 ... Magnetron, 6 ... Rectangular waveguide, 9 ... Excitation opening, 10
...... Motor (driving device), 21 …… Support section.

Claims (2)

[Claims] 1. An opening for excitation formed in an upper wall of a heating chamber, a main waveguide for guiding a high frequency wave output from a magnetron to the opening, and a rotatably surrounding the opening in the heating chamber. Is formed in a portion outside the opening of the rectangular waveguide, a drive device that rotationally drives the rectangular waveguide, and a rectangular waveguide that forms a tubular portion with the upper wall. In the high frequency heating device, the high frequency output from the magnetron is guided to the excitation opening through the main waveguide, the opening, and the rectangular waveguide to irradiate the heating chamber. A high-frequency heating device, characterized in that the waveguide is integrally formed into a container shape by drawing a metal plate. 2. The high-frequency heating device according to claim 1, wherein the rectangular waveguide has a support portion projectingly provided on the inner bottom surface thereof so as to be connected to the driving device.