JPS6237504B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a high frequency heating device.

The biggest problem with current devices of this type is eliminating uneven heating.

Conventionally, methods for solving this problem include providing a stirrer or a turntable. The former attempts to eliminate uneven heating by making the electric field strength in the heating chamber uniform by stirring the microwave in the heating chamber, and the latter aims to eliminate uneven heating by passing the object to be heated through electric fields of different strengths. This is intended to eliminate uneven heating by producing an effect similar to when all objects to be heated are placed under a uniform electric field.

However, installing a stirrer or a turntable inside the heating chamber is complicated and costly, and the effective volume of the heating chamber (the space in which the object to be heated can be placed) is
decreases, which is not desirable. It is also not very suitable for multistage cooking in which the heating chamber is partitioned into a plurality of chambers using saucers.

FIG. 1 shows a device of this kind that has already been proposed in view of the above, in which 1 is a heating chamber, 2 and 3 are first and second power feed ports bored in one side wall of the heating chamber; 4 is an impedance converter that communicates with the heating chamber 1 via the power feed ports 2 and 3; 5 is a waveguide that communicates with the converter; and 6 is the impedance converter that communicates with the heating chamber 1 via the waveguide and the converter 4.
7 and 8 are metal first and second shielding plates disposed near the first and second power supply ports 2 and 3, respectively, and the shielding Both plates 7 and 8 are fixed to a dielectric rod 9. Reference numeral 10 denotes a sliding means, such as a solenoid, for sliding the dielectric rod 9 in the direction of the arrow in the figure.
By sliding in the direction of the arrow in the figure, the first and second shielding plates 7 and 8 are connected to the first and second power supply ports 2 and 3.
The structure is configured so that they are alternately blocked.

In such a device, when the magnetron 6 is driven and the solenoid 10 is driven at the same time, the first and second power feed ports 2 and 3 are alternately blocked by the first and second shielding plates 7 and 8. Therefore, the microwaves emitted from the magnetron 6 are alternately guided into the heating chamber 1 through the first and second power feed ports 2 and 3.

Here, the coupling between the heating chamber 1 and the converter 4 changes from moment to moment, and the excitation phase within the converter 4 also changes from moment to moment. When such a phase change occurs, the mode of the microwaves supplied into the heating chamber 1 from the first and second power supply ports 2 and 3 also changes continuously, and therefore the electric field strength within the heating chamber 1 is also approximately constant. This will prevent uneven heating.

Further, as shown in FIG. 1, there is a saucer 11a that partitions the heating chamber 1 into multiple rooms, and a support 11b that supports the saucer.
When trying to perform multi-stage cooking using the multi-stage cooking utensil 11 consisting of
By arranging the two chambers so as to be respectively located in the two chambers partitioned by the cooking utensil 11, microwaves can be uniformly supplied to each chamber.

However, in such a device, since the shielding plates 2 and 3 are made of metal, sparks occur between the shielding plates 2 and 3 and the side surfaces of the converter 4, making it difficult to use in practice.

The present invention has been made in view of the above-mentioned problems, and will be described below with reference to Examples.

FIG. 2 shows an embodiment of the present invention, in which heating chambers 22 and 23 are first and second power feed ports bored in the side wall of the heating chamber, and 24 and 25 are the first and second power feed ports. The first and second waveguides communicate with each of the mouths, and 26 is a third waveguide that communicates with the first and second waveguides,
A magnetron 27 as a high frequency supply means is disposed in the third waveguide. 28 is an air guide, and the air guide is a blower fan (not shown).
The cooling air blown to the magnetron 27 is guided into the heating chamber 21 through a ventilation hole 29 formed in the side wall of the heating chamber. 30 and 31 are first and second waveguides arranged in the first and second waveguides 24 and 25, respectively.
The dielectric resonator 32 is a rotating means for rotating the dielectric resonator parallel to the bottom surface of the heating chamber 21, and one end of the rotating means is located within the air guide 28 and It consists of a dielectric rod 33 that passes through the wave tube 24 and whose other end reaches the second wave guide 25, and a windmill 34 attached to one end of the dielectric rod. Further, both the first and second dielectric resonators 30 and 31 are fixedly fixed to the dielectric rod 33 through the dielectric rod 33.

The coupling strength of the dielectric resonator with the microwave changes depending on the coupling direction with the microwave, that is, the dielectric resonator with height a, length b, and width c shown in Fig. 3. When 40 is most strongly coupled with the microwave A traveling in the direction perpendicular to the axc plane, the coupling with the microwave traveling in other directions is weaker than the above coupling force or results in no coupling at all.

FIG. 4 shows in detail the rotating means 32 and the first and second dielectric resonators 30, 31 fixed to the rotating means 32. Note that the same parts in the figure as in FIG. 2 are given the same numbers.

In such dielectric resonators 30, 31, two surfaces 30a, 30b and 31a, 31 located parallel to each other.
It is assumed that maximum coupling occurs with microwaves traveling perpendicular to b. In other words, when compared with the dielectric resonator 40 in FIG. 3 above, a
The xc plane corresponds to the two surfaces 30a, 30b and 31a, 31b of the first and second dielectric resonators 30 and 31, and the b x c plane in FIG. This corresponds to the planes 30 and 31 that intersect with the dielectric rod 33. For convenience, each side of the first and second dielectric resonators 30 and 31 in FIG.
This will be explained in correspondence with that shown in the figure.

a of each of the first and second dielectric resonators 30 and 31
The xc planes are fixed to the dielectric rod 33 at an angle of 90° to each other. Further, the windmill 34 is rotated by the cooling air passing through the air guide 28, and the first and second dielectric resonators 30 and 31 are also rotated accordingly.

In the apparatus of this embodiment configured as described above, the magnetron 27 oscillates microwaves and the windmill 34 is rotated by the cooling air that cools the magnetron 27.
The ×c plane is displaced momentarily with respect to the direction of propagation of the microwave.

When operated in this manner, the axc planes of the first and second dielectric resonators 30 and 31 are at a positional relationship of 90 degrees with respect to each other, so that the coupling strengths are out of phase by 180 degrees as shown in FIG. In the figure, the horizontal axis shows time, the vertical axis shows coupling strength, and changes in coupling strength of the first and second dielectric resonators 30 and 31 are shown by solid lines and broken lines, respectively.

At times t ₀ , t ₂ , t ₄ , and t ₆ in FIG. 5, the axc plane of the first dielectric resonator 30 is in the microwave traveling direction A
(clearly shown in Figure 2), and time
When t ₁ , t ₃ , t ₅ , t ₇ , ax of the second dielectric resonator 31
The c-plane is perpendicular to the microwave propagation direction A, and the coupling force is maximum (resonance mode). On the other hand, the first and second dielectric resonators 30 and 31 are
The coupling force is minimum at t ₁ , t ₃ , t ₅ , t ₇ or t ₀ , t ₂ , t ₄ , t ₆ (non-resonant mode).

Therefore, at times t ₀ , t ₂ , t ₄ , and t ₆ , the first dielectric resonator 30 exhibits the maximum coupling, so no microwave is output from the first waveguide 24 and the second waveguide Microwaves are output only from 25. Also, time t ₁ ,
At t ₃ , t ₅ , and t ₇ , the second dielectric resonator 31 exhibits maximum coupling, so no microwave is output from the second waveguide 25 , and no microwave is output from the first waveguide 24 . Output. Note that the dielectric resonator rotates continuously, and therefore its coupling strength also changes in an analog manner. Therefore, the first and second power supply ports 2
The amounts of microwaves supplied from the heating chambers 2 and 23 to the heating chamber 21 also change in an analog manner.

The rotation of the dielectric resonators 30 and 31 essentially has the same effect as the sliding movement of the shield plates 7 and 8 of the apparatus shown in FIG. In other words, the microwave excitation position within the waveguide changes due to a change in the microwave coupling between the dielectric resonators 30 and 31. Therefore, the mode of the microwaves supplied into the heating chamber 21 from each power supply port 22, 23 changes in an analog manner, so that the electric field strength within the heating chamber 21 is also uniform, and uneven heating does not occur. Further, since the dielectric resonators 30 and 31 are not made of conductive material, sparks will not be generated between them and the waveguide.

Further, as shown in FIG. 2, when performing multi-stage cooking using the multi-stage (two-stage in the figure) multi-stage cooking utensil 11, the first and second power supply ports 22 and 23 are connected to the cooking utensil 35. By arranging them so that they are located in two partitioned chambers, microwaves can be evenly supplied to each of the chambers.

A preferred example of the dielectric resonators 30 and 31 is one made of barium titanate with a dielectric constant εr=90, and has a height a=15 mm, a length b=7.5 mm, and a width c=6 mm.

Note that the present invention is not limited to the above-mentioned embodiments, and dielectric resonators arranged in a plurality of waveguides are alternately changed into a resonant mode and a non-resonant mode, and the microwaves supplied into the heating chamber are The mode may be changed in an analog manner.

As is clear from the above description, the high-frequency heating device of the present invention can make the electric field distribution in the heating chamber uniform without using a stirrer or a turntable, so the effective volume is widened and the usability is improved. Also, since it is powered by multiple outlets, multistage cooking is also possible. Furthermore, unlike the device shown in FIG. 1, sparks are not generated within the waveguide, so safety is high.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional device, FIG. 2 is a sectional view showing one implementation row of the present invention, FIG. 3 is a perspective view for explaining a dielectric resonator, and FIG. 4 is an implementation shown in FIG. FIG. 5 is an enlarged perspective view of the main part of the example, and is a characteristic diagram showing a change in coupling strength of the first and second dielectric resonators of the embodiment shown in FIG. 21... Heating chamber, 22, 23... Power supply port, 27
...Magnetron (high frequency supply means), 30,3
1...Dielectric resonator, 32... Rotating means.

Claims (1)

[Claims] 1. A heating chamber, a plurality of power supply ports drilled in the heating chamber, a plurality of waveguides communicating with the heating chamber through each of the power supply ports, and microwaves flowing into the heating chamber via the waveguides. a dielectric resonator arranged in each of the waveguides, the dielectric resonator being alternately set in a resonant mode and a non-resonant mode with respect to the microwave passing through the waveguide; A high-frequency heating device characterized by comprising a means for changing.