JPS60216490A - High frequency heating device - 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 The present invention relates to an improvement in the 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.

A proposal to provide slits in the partition plate constituting this radio maze (choke) was made in 1642 (1977-13);
rn + pitch ID mm or less) alone is not sufficient to provide a sufficient radio wave sealing effect, so a radio wave absorbing material is added to the outer wall of the partition plate. As a result, the number of parts increases, the structure is complicated, 91 it is difficult to assemble, and the external 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 a piece of metal,
It is designed to act as a 3P matching element that is independent of each other in terms of radio waves and efficiently guides leaked radio waves into the radio maze.

The purpose is to obtain a high frequency heating device that has a simple structure, good assemblability, small door 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 the outer box that houses 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 6 and surrounds the door 4.

Reference numeral 5 denotes a door rear plate that is in plane contact with the flange 2, and the 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 lower a of the radio wave 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. 9 is a transparent window cover provided on the outside of the viewing window 11 consisting of many small holes;
2 is a transparent 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.

Perspective views of the main parts of the door cover 8 and the maze cover 7b are shown in Figure 4 and Figure 4, respectively.
supports the metal plate 10 from the outer and inner surfaces, and therefore plays the role of mechanically reinforcing the metal piece 10. The labyrinth cover 71) is fixed to the peripheral end 5i1 of the door rear plate 50 by a convex portion 71]a protruding from its outer surface, and has a protrusion 111 on its inner surface.
The convex portions 7131) are located close to the inner surface of the metal piece 10 to prevent the metal piece 10 from being deformed by mechanical shocks from outside the door 4. The door cover 8, which has a 14-shaped cross section, has a stopper 13a protruding from its inner surface inserted into the gap between the metal pieces 10, and is tightly fixed to the outer surface of the metal piece 10, so that the door cover 8 is protected against mechanical shock from the outside of the metal piece 1n. Prevents deformation. The door cover 8 is not only used as a reinforcing material for the metal piece 10.

It also serves to fix the window outer cover 9 to the front of the door front plate B.

P FIG. 2 is an explanatory diagram showing the action of the metal piece 10.

The gap dimension B between adjacent metal pieces 10 is made larger than the entrance dimension 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 for leakage radio waves including higher-order modes and harmonics (the leakage radio waves can enter into the radio maze Z). is increased, and the electric field component generated between the metal pieces 10 (leaking radio waves cannot enter the radio wave maze Z) is reduced. That is, the metal piece 10 functions as a kind of matching element that is independent of each other in terms of radio waves and cannot efficiently guide leaked radio waves into the radio wave maze Z.

According to experiments, 100 metal pieces have a width W of 10 m, an overhang dimension H of 10 m, a gap dimension B of 10 m, and an inlet dimension A of 6 f.
fl++1. Under the conditions that the gap between the door rear plate 5 and the flange 2 is 1 mm, the high frequency output is 500 W, and the water load is 275 mm, the maximum leakage power amount at a distance of 5 crn from the aircraft is 0.03 mw/ltd (conventional example) Jitsukai 1976-13
Approximately 0.2 m w/crl with radio wave absorbing material for 0642
) and was found to be sufficiently practical.

P As described above, according to the present invention, a plurality of metal pieces are provided on the outermost edge of the door front plate, which is the peripheral wall of the radio maze facing the satush, and the gap size between adjacent metal pieces is set to be larger than the entrance dimension of the radio maze. A labyrinth cover that suppresses leakage radio waves and is fixed between the peripheral edge of the door rear plate and the metal piece, and 10 metal pieces.

Since the metal piece is mechanically reinforced by the door cover that is fixed using the gap, the radio wave leakage prevention effect can be maintained for a long period of time. In addition, the effect of preventing leakage of radio waves is excellent, and radio wave absorbing materials are not required.

In addition, the number of parts is reduced because the door cover also serves as a reinforcing material for the metal pieces and as an attachment part for the outer window cover.

It is possible to provide a high-frequency heating device with a simple structure, good assemblability, small door dimensions, and good space factor, and the effects of implementation are great.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the main parts of the high-frequency heating device of the present invention, and FIG.
The figure is a perspective view of the main part for explaining the action of the metal piece 10, FIG. 3 is a perspective view of the main part of the door cover 8, and FIG. 4 is a perspective view of the main part of the maze cover 7b. 7P 1... Heating chamber 2... Flange 3a.
... Sanosh 4 ... Door 5 ... Door
A Rear plate 5a... Peripheral edge of door rear plate 50 6... Door front plate 7... Radio maze 7a - Entrance of radio maze 7 7b... Maze cover 8...
・Door cover 9...Window cover 10...Metal
Piece 11...Peeking Window Applicant Hitachi Thermal Appliances Co., Ltd.

Claims (1)

[Claims] A flange (2) surrounding the entire circumference of the opening 1 of the heating chamber (1)
and a door (3a) consisting of a metal plate protruding in front of this flange (2) to open and close the opening.
A radio maze (7) is constructed around the periphery of 4) (-1 the same maze (7)
The door rear plate (5) is in planar contact with the flange (2), and a plurality of metal pieces (10
) surrounded by a door front plate (6) consisting of a metal piece (10)
The gap size (B) between adjacent ones is made larger than the entrance size (A) of the radio wave maze (7), and a door cover (8) made of a radio wave transparent dielectric is provided around the periphery of the door (4), It is tightly fixed to the outer surface of the metal piece (10), and the radio wave maze (7
) The labyrinth cover (7b) made of a radio wave transparent dielectric material covering the entrance (7a) of
a) and the metal piece (10), and
A high-frequency heating device characterized in that a transparent window cover (9) provided on the outside of a viewing window (11) is fixed to a door front plate (6) by a door cover (8). P