JPS6361754B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the radio wave leakage prevention structure of a door provided at the entrance of a heating chamber of a high-frequency heating device so as to be openable and closable.

A radio maze is installed around the door of the high-frequency heating device,
There is a proposal in Utility Model Application Publication No. 54-130642 to provide slits in the partition plates that make up this radio maze (width 2 mm ± 0.5 mm,
Since the radio wave sealing effect is not sufficient with just a pitch of 10 mm or less, radio wave absorbing material is added to the outer wall of the partition plate. As a result, the number of parts increases, the structure becomes complicated, assembly is difficult, and the outer dimensions of the door become large, resulting in a high-frequency heating device with a poor space factor.

Therefore, rather than providing a slit (slit) in the peripheral wall of the radio maze as in the conventional example, the present invention constructs a part of the peripheral wall of the radio maze from a plurality of metal pieces spaced sufficiently apart. By applying specific conditions to the metal pieces, they are made to act as mutually independent matching elements in terms of radio waves that efficiently guide leakage current into the radio maze.
The purpose is to obtain a high-frequency heating device that has a simple structure, good assemblability, small door external dimensions, good space factor, and durability.

Next, the structure and operation of the high frequency heating device of the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of essential parts of an embodiment of the high-frequency heating device of the present invention. 1 is a heating chamber into which an object to be heated is placed; 2 is a flange surrounding the entire opening of the heating chamber 1; 3 is an outer box that stores heating chamber 1;
The front periphery of the outer box 3 also serves as a sash 3a that extends the metal plate constituting the outer box 3 and surrounds the door 4. 5 is a door rear plate that makes plane contact with the flange 2;
This door rear plate 5 and the door front plate 6 forming the exterior form a radio wave maze 7. heating chamber 1, flange 2,
The sash 3a, the door rear plate 5 and the door front plate 6 are each made of a metal plate. A maze cover 7b made of a dielectric material that transmits radio waves is press-fitted into the entrance 7a of the radio maze 7, and a door cover 8 made of the same dielectric material is press-fitted onto the outer periphery of the door front plate 6. Reference numeral 9 denotes a transparent outer window cover provided on the outside of the viewing window 11 consisting of a large number of small holes, and 12 represents a transparent inner window cover provided on the heating chamber 1 side of the viewing window 11. Reference numeral 10 denotes a plurality of metal pieces periodically extending from the outermost edge of the door front plate 6 and facing the sash 3a. The main parts perspective views of the door cover 8 and the maze cover 7b are shown in FIGS. 3 and 4, respectively.
As shown in the figure, since both 8 and 7b support the metal piece 10 from the outside and inside as shown in FIG. 1, they serve as mechanical reinforcement for the metal piece 10. The maze cover 7b has a convex portion 7 protruding from its outer surface.
The metal piece 10 is fixed to the circumferential edge 5a of the door rear plate 5 by ba, and the convex part 7bb protruding to the inner surface is placed close to the inner surface of the metal piece 10 to prevent deformation of the metal piece 10 from mechanical shock from the outside of the door 4. There is. The door cover 8, which has an L-shaped cross section, has a stopper 8a protruding from its inner surface inserted into the gap between the metal pieces 10, and tightly fixed to the outer surface of the metal piece 10, so that the door cover 8 can be stopped by a mechanical shock from the outside of the metal piece 10. Prevents deformation.
The door cover 8 not only serves as a reinforcing material for the metal piece 10 but also serves to fix the window outer cover 9 to the front surface of the door front plate 6.

FIG. 2 is an explanatory diagram showing the action of the metal piece 10. Gap dimension B between adjacent metal pieces 10
is set to be equal to or larger than the entrance dimension A of the radio maze 7. Therefore, an electric field component is generated between the tip of the metal piece 10 and the peripheral edge 5a of the door rear plate 5 against leakage radio waves including higher-order modes and harmonics (the leakage radio waves can enter into the radio maze 7). is increased, and the electric field component generated between the metal pieces 10 (leaking radio waves cannot enter the radio wave maze 7) is reduced.
That is, the metal piece 10 functions as a kind of matching element that efficiently guides leaked radio waves into the radio wave maze 7 and is independent of each other in terms of radio waves.

According to experiments, the width W of the metal piece 10 is 10 mm, the overhang dimension H is 10 mm, the gap dimension B is 10 mm, the entrance dimension A is 6 mm, the gap between the door rear plate 5 and the flange 2 is 1 mm, and the high frequency output is 500 W. , water load is 275ml
Under these conditions, the maximum leakage power at a distance of 5 cm from the aircraft is as small as 0.03 mW/cm ² (conventional example, 130642/1983, with a radio wave absorbing material, was approximately 0.2 mW/cm ² ), which is sufficient for practical use. I understand.

As described above, according to the present invention, a plurality of metal pieces are provided on the outermost periphery of the door front plate forming the peripheral wall of the radio maze facing the sash, and the gap size between adjacent metal pieces is made equal to the entrance size of the radio maze. more than that,
In addition to suppressing leakage radio waves, the metal pieces are mechanically reinforced by the labyrinth cover that is fixed between the peripheral edge of the door rear plate and the metal pieces, and the door cover that is fixed using the gaps between the metal pieces. , the radio wave leakage prevention effect can be maintained for a long time. Furthermore, since it has a large radio wave leakage prevention effect, there is no need for radio wave absorbing materials, the number of parts is small, the structure is simple and easy to assemble, the outside diameter of the door is small, and the high-frequency heating device has a good space factor. The effect of doing so is huge.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the main part of the high-frequency heating device of the present invention, FIG. 2 is a perspective view of the main part for explaining the action of the metal piece 10, and FIG. 3 is a perspective view of the main part of the door cover 8. , FIG. 4 is a perspective view of the main part of the maze cover 7b. DESCRIPTION OF SYMBOLS 1...Heating chamber, 2...Flange, 3a...Sash, 4...Door, 5...Door rear plate, 5a...Peripheral end of door rear plate 5, 6...Door front plate, 7... Radio maze, 7a...entrance of radio maze 7, 7b...maze cover, 8...door cover, 10...metal piece.

Claims (1)

[Claims] 1 Flange 2 surrounding the entire opening of heating chamber 1
A sash 3a made of a metal plate protrudes in front of the flange 2, and a radio labyrinth 7 is formed around the periphery of the door 4 that opens and closes the opening. and a door front plate 6 consisting of a plurality of metal pieces 10 whose outermost edge faces the sash 3a, and the distance between adjacent metal pieces 10 is such that the dimension B is equal to or similar to the entrance dimension A of the radio maze 7. In addition to the above, a door cover 8 made of a radio wave transparent dielectric is provided on the periphery of the door 4, and a stopper 8a protruding inward is provided on the door cover 8,
A labyrinth cover 7b made of a radio-transparent dielectric material is press-fitted between the metal pieces 10 and tightly fixed to the outer surface of the metal pieces 10, and covers the entrance 7a of the radio-wave labyrinth 7. A high-frequency heating device characterized in that it is press-fitted and fixed between 5a and a metal piece 10.