JPS61116789A - 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 an improvement in the radio wave leakage prevention mechanism of the sheathed heater attachment/detachment part of a high-frequency heating device in which a sheathed heater is detachably installed in a heating chamber for performing high-frequency heating and heater heating. .

Conventional technology A sheathed heater is bent as appropriate and placed in a heating chamber, two terminals of the sheathed heater to which a commercial frequency voltage is applied protrude outside the heating chamber, and the two terminals are fixed to the inner surface of a single metal case. The length of this metal tube was formed to be 1/4 of the wavelength, and the axial direction of this metal tube was perpendicular to the peripheral wall of the heating chamber (for example, 54-90640). Therefore, the radio wave leakage prevention structure of the heater terminal portion is structured to protrude significantly toward the outer surface of the heating chamber.

The problem to be solved by the invention is that the outer dimensions of the high-frequency heating device become large due to the radio wave prevention structure of the terminal portion of the heater.

Means for solving the problem: An oval and dish-shaped metal case with a bottom surface having a radius of approximately one wavelength of the high frequency is fixed to the peripheral wall of the heating chamber, and this metal case is penetrated by two removable terminals of a sheathed heater. It is something that

Effect: The oval, dish-shaped metal case made up of two semicircles resonates with the leakage radio waves from the sheathed heater attachment/detachment section.

Act as a band rejection filter.

Embodiment The structure and operation of a high-frequency heating device according to an embodiment of the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of a main part of an embodiment of the present invention, viewed from the XY arrow direction in FIG. 3. FIG. 1 is a heating chamber into which the object to be heated is placed, and 2 is a peripheral wall of the heating chamber. 6 is a sheathed heater that raises the air temperature in heating chamber 1 to a temperature suitable for cooking;
The terminal 4 for supplying electric power to the sheathed heater 3 is constituted by a round bar with a rounded end so that it can be attached and detached freely.

The sheathed heater 6 is connected to the heating chamber 1 through the through hole 5 of the heating chamber peripheral wall 2.
It protrudes to the outside. 6 is made into an oval shape by placing two semicircles with a radius of approximately 7 (λ: wavelength of high frequency) centered on the center axis of each terminal 4 of the sheath heating λ 3 and facing each other with a distance of 7 between the two terminals 4, 4. It is a single metal case formed into a dish shape. Two metal tubes 8.8 are fixed to the inner wall of the metal case 6, and the two terminals 4, 4 pass through them one by one. 9 is sheathed heater 6
This is an insulating tube that prevents the outer surface of the metal tube 8 from coming into electrical contact with the metal tube 8.

10 is an entrance of a resonance cavity 11 surrounded by the outer surface of the metal tube 8, the inner surface of the metal case 8, and the outer surface of the heating chamber peripheral wall 2.

The length of the radio wave propagation path 16 between the entrance 10 of the resonant cavity 11 and the inner surface 12 of the half inside of the metal case B is approximately λ 7.

FIG. 2 is an external view of the metal case B seen from direction A in FIG. 3. It can be seen from FIG. 2 that the metal case 6 has an oval shape.

In FIG. 6, 14 is the bottom plate of the outer box housing the heating chamber 1, and 15 is the rear plate of the outer box.

Next, the effects of the above embodiment will be explained. The 1ici that is coaxially coupled with the through hole 5 of the heating chamber peripheral wall 2 and the sheathed heater 3 and tries to leak to the outside passes through the inlet 10 and enters the resonance cavity 1.
Propagates within 1. When the radius of the semi-interior of the metal case 6 is set to about 1 of the wavelength of the high frequency wave and the lengths of the metal tubes 8, 8 fixed to the inner wall of the metal case 6 are adjusted, the impedance increases near the entrance 10 due to resonance with the leaked radio waves. No, radio waves will no longer leak to the outside. In this case, the resonant cavity 11 acts as a band-stop filter.

According to experiments, the wavelength λ of high frequency is 122 mm (frequency 2
．． 450 MHz), high frequency output is 500W, water load is 275 CC1λ, and the semi-inner radius is 60W! 7), the depth 16 of the metal case 6 is 20, and the length 17 of the metal tube 8 is 18+.
a.

When the inner diameter is 10.5 mm, the outer diameter is 14 mm, the diameter of the through hole 5 in the heating chamber peripheral wall 2 is 10.5 mm, the outer diameter of the V-Z heater 6 is 6.7 mm, and the interval 7 is 20 mm. The amount of leakage radio waves from the vicinity of terminal 4 was 1 mW or less, and it was confirmed that it can be used for practical purposes. What should be noted here is that the depth 16 of the metal case 6 is 20++lI++. The metal case can be made much thinner than when λ17 is set to the length of the metal tube fixed to the inner surface of the metal case as in the conventional example. In other words, the outer box of the high-frequency heating device becomes smaller.

Effects of the Invention As described above, according to the present invention, there is provided an oval and dish-shaped metal case in which the bottom face is parallel to the heating chamber wall and has two semicircles facing each other and having a radius of about 1/4 wavelength of the high frequency wave. It is fixed to the heating chamber chest wall, and a band rejection filter consisting of a resonant cavity is formed inside this metal case to prevent radio wave leakage from each terminal of the sheathed heater.The structure for preventing radio wave leakage is thin, and the entire high frequency heating device can be made compact.

[Brief explanation of the drawing]

FIG. 1 shows a third embodiment of the high frequency heating device of the present invention.
FIG. 3 is a cross-sectional view of the main parts seen from the XY arrow directions in the figure. FIG. 2 is an external view of the metal case 6 seen from direction A in FIG. 3, and FIG. 6 is a partially cutaway side view of the metal case 6. 1... Heating chamber, 2... Heating chamber peripheral wall. 6... Sheathed heater, 4,4... Terminal. 6... Metal case, 11... Resonance cavity.

Claims (1)

[Claims] A sheathed heater (3) is detachably installed in a heating chamber (1) that performs high-frequency heating and heater heating, and the bottom surface of the heating chamber peripheral wall (2) has an oval shape with a radius of approximately 1/4 wavelength of the high frequency. A plate-shaped metal case (6) is fixed to the metal case (6), and a band rejection filter consisting of a resonant cavity (11) is formed in the metal case (6) to connect the terminals (4), (
4) A high-frequency heating device characterized by preventing radio wave leakage from.