JPS58181289A - 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 The present invention relates to a high frequency heating device that couples a waveguide and a heating chamber in a so-called coaxial manner.

Conventionally, in the case of coupling between a waveguide and a heating chamber using a coaxial inner conductor as an antenna to feed power, if the length of the coaxial outer conductor, that is, the length of the coupling hole is short, even if the antenna is installed at the center of the upper surface of the heating chamber. Multiple identical loads placed symmetrically on the antenna could not be heated equally. This is because the electric fields of the coupling hole and the antenna are not the same electric field all around. This is because the high frequency electromagnetic waves from the high frequency oscillator come from one side, resulting in 3 veggies. Similarly, when the antenna is rotated with a rotational component almost perpendicular to the above antenna, the way the high-frequency electromagnetic waves are radiated is when the rotational component faces toward the high-frequency oscillator and when it faces the opposite direction. As the impedance of the load of the high frequency oscillator changes greatly, the impedance of the high frequency oscillator often deviates from the impedance that produces a high output, resulting in a decrease in output and poor efficiency. Ta. To solve this problem, it is necessary to make the length of the coaxial outer conductor one-fourth or more of the wavelength of the high-frequency electromagnetic wave, and the shape of the high-frequency heating device itself becomes large.

For example, the length component l of the coupling hole that couples the waveguide and the heating chamber
is provided over the entire circumference, the impedance will be different when the horizontal rotational component of the rotating antenna faces the magnetron side of the waveguide (solid line A) and when it faces the opposite direction (dashed line B).
As shown in Figure 1, the impedance of the magnetron (in the state of It was getting shorter. Also, since the high frequency outputs in state A and state B are significantly different, when multiple loads are placed in the heating chamber, the amount of heat heated by the load on the magnetron side of the heating chamber and the load on the opposite side will be large. It was different.

The present invention aims to improve the output efficiency and downsize the coaxial outer conductor by changing the length of the outer conductor of the coaxial part that connects the waveguide and the heating chamber on the high frequency oscillator side and on the opposite side. .

The high-frequency heating device of the present invention changes the high-frequency electric field between the inner conductors within the coaxial portion by changing the length of the outer conductor of the coaxial portion, especially by making the length on the high-frequency oscillator side shorter than other portions. This makes it an ideal coaxial device.

Embodiments of the present invention will be described below with reference to FIGS. 2 to 6.

In FIG. 2, reference numeral 1 denotes a main body of the high-frequency heating device, and a door 3 is provided at the opening of a heating chamber 2 provided in the main body 1 so as to be openable and closable. 4 is a heater plate installed at the top of page 5 of the main body 1. When using this heater plate 4 for boiling, etc., the electric power for the plate heater 6 shown in FIG. Each is configured to be controllable. Reference numeral 7 designates an operating knob B for controlling the output of a magnetron 8 used as an example of a heater and a high frequency generator provided in the heating chamber 2.

In FIG. 3, reference numeral 9 denotes a plate made of a heat-resistant dielectric material provided at the negative side of the plate heater 6. 10 is a heater provided at the top inside the heating chamber 2, and 11 is a heater provided at the bottom of the heating chamber outside the heating chamber 2. The inside of the heating chamber 2 can be efficiently heated by the heaters 10 and 11. 12 is a heat insulating material provided around the outer periphery of the heating chamber wall 13. 14 is a tapered waveguide that transmits the high frequency waves generated by the magnetron 8 into the heating chamber 2. 16 is a waveguide 14. A rotating antenna having a horizontal rotating component 17 is provided so as to pass through the upper wall 16 of the heating chamber and face into the heating chamber 2. The rotary antenna 6 vane antenna 15 is rotated by a motor 19 via a belt 18.

The main parts of this embodiment will be explained below.

As shown in FIGS. 4 and 5, by making the length component a of the coupling hole 2° different on the magnetron 8 side and the opposite side, states A and B can be created as shown in the Smith diagram of FIG. 6. The impedances of the two are almost equal, and the drawbacks of the conventional method can be completely eliminated. In this embodiment, the length component 2 and the metal fitting that supports the spacer 21 made of a low-loss dielectric that seals the coupling hole 2o are made integrally.

FIG. 7 shows a second embodiment of the present invention, in which the rotating antenna 1
The same effect can be obtained by rotating the stirrer 22 electrically connected to the rotary antenna 15 using 6 as a rotation axis. 23 is a stirrer holding member for supporting the stirrer 22.

FIGS. 8 and 9 show a third embodiment of the present invention.

By shifting the center of the coupling hole 2o and the center of the rotation axis of the antenna 16, the impedance of the coupling hole 2o is changed, and the load impedance changes slightly when the rotary antenna 16 starts rotating.

As described above, according to the present invention, the following effects can be obtained.

(1) High frequency output efficiency is achieved because impedance changes are small even when the rotating antenna or stirrer rotates.

(2) Due to the reason in (1) above, the heating balance is good when multiple loads are applied.

(3) Since the length of the coaxial portion may be short, the high frequency heating device can be configured compactly.

(4) Due to the reason in (1) above, there is no adverse effect on the magnetron.

[Brief explanation of the drawing]

Fig. 1 is a Smith impedance diagram of a conventional high-frequency heating device, Fig. 2 is an external perspective view of a high-frequency heating device according to an embodiment of the present invention, Fig. 3 is a front sectional view of the same, and Fig. 4 is the main part of the same. 6 is a plan view of the same essential parts, FIG. 6 is a Smith impedance chart of the same, FIG. 7 is an enlarged sectional view of essential parts of the high-frequency heating device according to the second embodiment of the present invention, and FIG. 8 is an enlarged sectional view of the essential parts. 9 is an enlarged cross-sectional view of a main part of a high-frequency heating device according to a third embodiment of the present invention, and FIG. 9 is a plan view of the main part. 2. Heating chamber, 8. Magnetron (high frequency oscillator), 14... Waveguide, 15.
...Rotating antenna, 1ryo00080. Horizontal rotational component, 20. ,,,. Coupling hole, 21... S6-Ser, 22...
・Staller, g , , , , length component. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure name 2 Figure 3 Figure 6 * Hamatakui Narrow 1'X, 2--1
-~1.1 Tokyo Station Inisu Castle Figure 8 Figure 9

Claims (1)

Scope of Claims: (1) A heating chamber that stores an object to be heated, a high-frequency oscillator that supplies high-frequency electromagnetic waves into the heating chamber, a waveguide that couples the high-frequency oscillator and the heating chamber, and a waveguide that connects the high-frequency oscillator and the heating chamber. The coupling portion between the wave tube and the heated chamber has a coupling hole having a size equal to the oscillation wavelength of the high-frequency electromagnetic wave, an antenna is provided approximately in the center of the coupling hole, and the antenna connects the waveguide to the heating chamber. A high-frequency heating device configured to couple the heating chamber with each other, and to make characteristic impedances of the coupling hole and the antenna different between the high-frequency oscillator side and the opposite side of the waveguide. (2) The high-frequency heating device according to claim 1, wherein the length component l of the parallel portion of the coupling holes parallel to the antenna is made different on the side of the waveguide provided with the high-frequency oscillator and on the opposite side. . (3) The high-frequency heating device according to claim 1, wherein the center of the coupling hole and the center of the aging antenna are shifted by 2 bases. (4) The high-frequency heating device according to claim 2, wherein the length component I of the coupling hole is made shorter on the high-frequency oscillator side than on the opposite side. (6) The high-frequency heating device according to claim 1, wherein the antenna is provided with a tortenoid that is substantially perpendicular to the antenna, and the antenna is rotatable about a rotation axis.