JPS61124092A - Door unit for high frequency heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a door device for a high frequency heating device such as a microwave oven.

Conventional technology In general, high-frequency heating devices such as microwave ovens are provided with a door that can be opened and closed to close the opening through which objects to be heated are taken in and out of the heating chamber, and around the door prevents high-frequency waves from leaking to the outside. A high frequency attenuation device is provided.

Many proposals have been made for this high frequency attenuation device, and one of the most commonly used is the choke method.

This method is characterized in that it has a choke groove, and that the effective depth from the choke groove opening to the end of the choke groove is 1/4 of the wavelength of the high frequency wave used. It is. (eg US Pat. No. 3,182,164 and drawings).

In addition, as shown in FIG. 5, there is also a device with double choke grooves to further enhance the damping effect. (PCT Patent 2 Publication II & LWO8410183) In the figure, a partition wall 3 is provided between the outer wall surface 1 and the inner wall surface 2 of the choke groove, and the partition wall 3 has notches 4 at equal intervals, and Square holes 5 are provided alternately with the notches 4. The partition wall 3 has a ceiling part 6 that partially closes the groove opening, and a partition part 7 that is parallel to the inner wall surface 2 and extends to the middle thereof.

When looking at the cross section of the choke groove, the groove between the inner wall surface 2 and the partition portion 7 parallel thereto becomes a high frequency introduction line,
The width of this groove becomes wider beyond the terminal end of the partition, and the characteristic impedance of the high frequency line changes.

As mentioned above, by optimizing the combination of characteristic impedance of each narrow groove and wide groove, the depth of the choke groove can be reduced by 1/2.
It becomes possible to make the wavelength shorter than 4 wavelengths. The groove between the partition wall 3 and the outer wall surface 1 can also be called a second choke groove, and further enhances the damping effect of the first choke groove. Further, the cutout portion 4 of the partition wall 3 is provided to provide a blocking effect of high frequency waves propagating in the longitudinal direction of the partition wall 3.

Problems to be Solved by the Invention In the choke groove configured as described above, the positional accuracy of the partition wall 3 is an extremely important factor for high frequency attenuation performance. That is, due to a dimensional change in the width of the high-frequency introduction line, the characteristic impedance changes, which significantly worsens the damping effect.

Normally, the partition wall 3 is often joined to the bottom of the choke groove by a method such as spot welding, but there is a problem that positioning during welding is difficult and it is difficult to improve dimensional accuracy. Further, since the actual angle of the rising portion of the partition wall 3 easily changes, there is a drawback that the groove width tends to change 6 as a result. Methods have been taken to address these problems, or to further install a radio wave absorber such as ferrite, but this results in an increase in the dimensions of the surrounding frame of the door, which is disadvantageous in terms of weight and cost. there were.

The present invention solves these conventional problems and provides an excellent door device that has a simple and compact configuration and does not reduce the high frequency attenuation effect.

Means for Solving the Problems The door device of the high frequency heating device of the present invention has notches and square holes on the four sides around the metal door body. Note that the protruding end 15a of the partition portion and the upper end side 13b of the square hole portion are made to coincide with each other.

FIG. 2 shows a cross section of a door having a choke groove as described above. A cover 16 made of a material such as resin is provided on the open side of the choke groove, and a transparent cover 17 is attached to the front side. There is. A large number of small holes 20 through which the heating chamber 19 can be seen are provided in the center of the chamber.

In this way, the attachment position of the outer wall surface 11 to the door body is a position where it is pressed tightly against the L-shaped corner of the groove bottom surface 9 and the partial outer part 10, so that it is possible to use welding or other joining means. Positioning can be performed with extremely high precision. Further, the tip of the outer portion 10 and the bottom side 12a of the cutout portion 12 of the outer wall surface 11 are aligned.

Further, the outer wall surface 11 has a metal portion continuous in the longitudinal direction at its rising root portion, and has a circular arc portion at its bent portion, so that it has high strength against bending from the bent portion. In particular, due to the double structure with the outer portion 10, the position does not easily change in response to an external force applied in an outward direction. On the other hand, even if the root portion is strengthened, the bases of the square hole portion 13 and the notch portion 12 become relatively weak, but the lack of strength is compensated for by the slight radius of the corner provided during each machining process.

In FIG. 3 (second embodiment), the outer wall surface 21 is formed integrally with the groove bottom surface 22 and the inner wall surface 23 from a single metal plate. FIG. 4 shows a developed view before bending. A notch 24 and a square hole 25 provided in the outer wall surface 21 are the same as those in the first embodiment. The position indicated by the broken line in FIG. 4 is much easier to manufacture and dimensional accuracy can be achieved than when the bending process is performed by joining separate parts by means such as welding.

This has the advantage that it is possible to reduce the amount of materials used, and it is also possible to make the product smaller and lighter.

Effects of the Invention As described above, the door device of the high-frequency heating device of the present invention uses a periodic structure having alternating notches and square holes as the outer wall surface of the choke groove, and at the same time has a longitudinally continuous portion at its base. By providing this, the dimensional position of each part of the groove can be maintained with high precision, eliminating the possibility of reducing the high frequency damping effect due to processing precision, and making it extremely advantageous for reducing the size and weight of the cone. I can do it.

[Brief explanation of the drawing]

1 is a perspective view including a cross section of a main part of a choke groove according to a first embodiment of the present invention, FIG. 2 is a sectional view of a main part thereof, FIG. The figure is a developed view of the original body before processing, and Figure S is a perspective view including a cross section of the main part of a conventional choke groove. 8... Inner wall surface, 9... Groove bottom surface, 11.
...Outer wall surface, 12...Notch, 13...
...Square hole part. Name of agent: Patent attorney Toshio Nakao
lrJ! A. Inner wall surface 9...Groove bottom surface lt.Outer surface Fig. 3? !・・Outer 9 surfaces 22・Door 1 24・・Tip part Fig. 5Δ

Claims (1)

[Claims] A groove portion having an opening on the heating chamber side and a bottom portion on the front side of the door is provided on four sides around the metal door that closes the high-frequency heating chamber, and the outer wall surface of the groove portion is a rising portion from the groove bottom portion. A notch having a bottom at least closer to the heating chamber side and a square hole having one end at approximately the same position are alternately and continuously provided, and the tip thereof is formed into an L shape partially toward the inside of the groove. A door device for a high-frequency heating device that has a bendable structure.