JPS6316861B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a high-frequency heating device, and particularly to a sealing structure for a door portion thereof.

Conventional configuration and its problems Traditionally, the chiyoke seal method has been widely used to shield radio waves leaking from the door.
Since the shielding performance of the chi-yoke seal method alone is not very good, some systems have used a chi-yoke seal and a radio wave absorber in combination, or provided multiple slits at the high-frequency electromagnetic wave entrance part of the chi-yoke groove or inside the chi-yoke groove.

Hereinafter, a door seal structure of a conventional high-frequency heating device will be described with reference to the drawings. In addition, the same numbers shall be given to the same members.

In FIG. 1, a high-frequency heating device 2, which also serves as ventilation, is suspended below a shelf 3 above a stationary stove 1. High frequency heating device 2 is stove 1
air intake 4 for ventilation and lighting device 5 for the stove area
have. The high-frequency heating device 2 also includes a door 6 that can be opened and closed, and an operation panel 7 for the high-frequency heating device 2.
It has a lever 8 for opening and closing the door 6, a ventilation switch 9, and a lighting switch 10.

FIG. 2 is a sectional view of the high frequency heating device 2 and the shelf 3. A fluorescent lamp 11 is provided as the illumination device 5,
It is protected by a lighting cover 12 made of glass.

Steam and heat from the stove 1 pass through a filter 13 and are exhausted to the outside by a cross flow fan 14. High-frequency electromagnetic waves from a magnetron (not shown) are supplied to the lower part of the heating chamber 15 of the high-frequency heating device 2 through a rotating antenna 18 rotated by a waveguide 16 and a pulley 17 . At the top of the rotating antenna 18 is a plate 1 made of a lossy dielectric material.
9 is arranged, and a door 6 that can be opened and closed by a hinge (not shown) is provided on the front surface of the heating chamber 15.

FIG. 3 is an enlarged cross-sectional view of a main part of a door portion of a high-frequency heating device that uses both a chiyoke seal system and a radio wave absorber. A sealing plate 20 is provided on the inner surface of the door 6, and both form a partially open chute groove 21. A front plate 22 is provided around the opening of the heating chamber 15, and faces the outer peripheral surface of the sealing plate 20 when the door 6 is closed. Reference numeral 23 denotes a frame attached to the front plate 22, and a radio wave absorber 24 made of rubber or the like mixed with manganese or nickel ferrite is provided inside this frame.

According to this configuration, leakage radio waves are transmitted through the chiyoke groove 21
The remaining leakage radio waves are absorbed by the radio wave absorber 24. In this case, the shielding performance against high-frequency electromagnetic waves was sufficient, but in the case of a microwave oven, for example, the radio wave absorber is weak against heat and shocks caused by opening and closing the door, which caused problems in terms of durability.

4 shows a case in which a plurality of slits 25 are provided in the sealing plate 20 at the inlet portion of the high-frequency electromagnetic wave of the check groove 21, and FIG. This is because the direction of the radio waves leaking from the heating chamber 15 is not just one direction but random, and for example, the attenuation effect in the chiyoke groove 21 is poor for radio waves leaking in a direction other than perpendicular to the chiyoke groove 21. , it is difficult to attenuate due to the chain yoke groove 21. Therefore, a slit 25 was provided for the purpose of aligning the traveling direction of the high-frequency electromagnetic waves that were about to leak.

However, the sealing plate 20 at the high-frequency electromagnetic wave inlet portion of the cheese groove 21 is provided with a plurality of slits 25.
In the case shown in the figure, the slit 25 is a place where the leakage radio waves from the heating chamber 15 directly leak, so a strong electric field is generated between the slits 25, and especially when there is no load on the heating chamber, the electric field becomes even stronger. This has the problem that spark discharge may occur. To solve this problem, it is necessary to cover the slit 25 with resin or the like, or to provide a gap between the slit 25 and the peripheral edge of the heating chamber facing the slit 25, which increases the size and cost.
The shielding ability was reduced due to the gaps.

In addition, a plurality of slits 2 are provided inside the chiyoke groove 21.
In the case shown in Fig. 5 where 5 is provided, the slit 25
Although no spark discharge occurs between the two, the slit 25 must be provided in a separate part, and the slit 25 must be provided in a narrow space, resulting in poor machinability and workability and increased costs. .

OBJECTS OF THE INVENTION In view of the above-mentioned drawbacks, the present invention provides a seal structure for a high-frequency heating device that has a sufficient ability to shield high-frequency electromagnetic waves and is inexpensive.

Structure of the Invention In order to achieve this object, the high-frequency heating device of the present invention has a structure in which a plurality of slits each having a length of 1/4 wavelength of the high-frequency electromagnetic wave are provided at the exit portion of the high-frequency electromagnetic wave of the choke groove, so that a strong electric field is generated between the slits. This device eliminates the need for extra parts, is inexpensive, and has sufficient shielding ability for high-frequency electromagnetic waves.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below based on the drawings.

FIG. 6 is an enlarged sectional view of the main part of the door 6. 6th
In the figure, an opening peripheral member 26 is provided around the opening of the heating chamber 15, and a chiyoke groove 21 is formed in a portion of the door 6 that faces the opening peripheral member 26, and the high-frequency electromagnetic wave exit side of the chiyoke groove 21 is opened. A slit 25 extending substantially parallel to the peripheral member 26
is configured. Further, covers 27 and 28 made of a lossy dielectric material are provided in the cheese yoke groove 21 and the slit 25 to protect them from dust and the like.

FIG. 7 is an enlarged perspective view of the chiyoke groove 21. FIG.
In FIG. 7, the chiyoke groove 21 is composed of a door body 29 having a slit 25 and a sealing plate 20 that seals a part of the chiyoke groove 21, and around the central part of the sealing plate 20, there is a 1/10th of the wavelength of high-frequency electromagnetic waves. A plurality of small holes 30 are provided so that the inside of the heating chamber 15 can be seen.

The operation of the above configuration will be explained below.
As a method of preventing radio wave leakage from the gap between the heating chamber 15 and the door 6, the chiyoke groove 21 alone cannot sufficiently shield radio waves. This is because the direction of the radio waves leaking from the heating chamber 15 is not only one direction, but also random, and there is also a component in a direction parallel to the chiyoke groove 21. This is because the chiyoke groove 21 has little sealing effect against radio waves leaking in a direction parallel to the chiyoke groove 21, and the amount of radio wave leakage increases as a whole.

Therefore, a plurality of slits 2
By providing the slow wave circuit consisting of 5, radio waves in this direction propagate through the slow wave circuit, and the radio waves leaking to the outside of the door 6 are almost completely eliminated.

However, there are various plans as to where to install the slow wave circuit such as the slit 25, but in the present invention, by providing it on the exit side of the high frequency electromagnetic wave of the choke groove 21, leakage radio waves to the slit 25 are prevented from flowing into the choke groove 21. Only parallel components will arrive. Therefore, the electric field generated between the slits 25 is weaker than when the cheese yoke groove 21 is provided on the inlet side of the leaked high-frequency electromagnetic waves, so that the slit 25 is abnormally heated even when the high-frequency heating device is operated under no load. Never.

Furthermore, since the slit 25 is provided at a location that corresponds to the radio wave path of leaked radio waves, the radio wave shielding performance is great.

Furthermore, since the tip of the slit 25 is an open end and the base side of the slit 25 is short-circuited, most of the radio waves that have propagated up to the entrance of the cheese yoke groove 21 enter the inside of the cheese yoke groove 21. The effect of the grooves becomes even greater.

Effects of the Invention As described above, according to the present invention, the following great effects can be obtained.

(1) By providing multiple slits outside the cheese groove, that is, at the exit portion of the high-frequency electromagnetic wave from the cheese groove, the amount of leakage radio waves reaching the slit portion is reduced, and the electric field generated between the slits is weakened, causing sparks, etc. This prevents the slit from being abnormally heated.

(2) The metal part of the door consists of only the door body that forms the chiyoke groove and the sealing plate that seals a part of the chiyoke groove, so the number of components is reduced and the door can be constructed at low cost. become.

(3) Since the slit is provided outside the chain yoke groove, it does not take much time to manufacture, and the most effective shape can be designed and manufactured.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the installed state of a conventional high-frequency heating device, Figure 2 is an enlarged sectional view of the same main part, Figure 3 is an enlarged sectional view of the main part of the same door, and Figure 4 is another similar door. FIG. 5 is an enlarged cross-sectional view of the main part of another door part, FIG. FIG. 7 is an enlarged perspective view of the main parts of the door. 6...Door, 15...Heating chamber, 20...Sealing plate, 21...Chiyoke groove, 25...Slit, 2
7, 28...Cover, 29...Door body.

Claims (1)

[Scope of Claims] 1. A heating chamber for storing an object to be heated is provided, a door that can be freely opened and closed is provided in a part of the heating chamber, and the door has a chiyoke groove located opposite to the periphery of the opening of the heating chamber when the door is closed. and a sealing plate, the door body is provided with a plurality of slits parallel to the opening periphery of the high-frequency electromagnetic wave exit portion of the choke groove, and the length of the slits is substantially equal to the high-frequency electromagnetic wave exit portion. High frequency heating device with a quarter wavelength. 2. The high-frequency heating device according to claim 1, wherein the sealing plate partially seals the cheese groove, and the tip of the slit is bent in a direction opposite to the heating chamber. 3. The high-frequency heating device according to claim 1, wherein a cover made of a dielectric material is provided to cover the slit portion, and the cover and the peripheral edge of the opening of the heating chamber are in close contact with each other.