JPS6241387B2 - - Google Patents

Description

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

In recent years, high-frequency heating devices have been proposed that eliminate the stirrer and turntable and instead supply microwaves from a plurality of power ports to prevent uneven heating from occurring in order to effectively utilize the inside of the refrigerator.

1 and 2 show a device of this kind that has already been proposed, in which 1 is a heating chamber equipped with a main power supply port 2 and a sub power supply port 3, and 4 is in communication with the heating chamber 1 via the main power supply port 3. The main waveguide 5 is a sub waveguide that connects the sub power feeding port 3 with two coupling holes 6, 6 bored on one side of the main waveguide, and the coupling holes 6, 6 are separated by a distance l. They are placed at a distance from each other. 7 is a magnetron arranged at one end of the main wave tube 4.

In such a device, by appropriately selecting the size and distance l of the coupling holes 6, 6 based on the theory of a well-known directional coupler, a micrometer can be connected to the heating chamber 1 from each of the main power supply port 2 and the sub power supply port 3. It is possible to supply waves.

However, with such a device, if the amount of load (subject to be heated) in the heating chamber 1 is constant, it is possible to supply microwaves from each power supply port, but normally with such a device, microwaves can be supplied from each power supply port. Since the amount of load is not constant, there may be cases where power is not supplied from each of the above-mentioned power supply ports at the same time, and since the impedance seen from the magnetron 7 during heating is constant, the amount of microwaves supplied from each power supply port is constant, Therefore, standing waves are generated within the heating chamber 1 even when power is supplied from multiple ports.

Figures 3 and 4 show a high-frequency heating device that has already been proposed in view of this point, and its feature is that it uses a ferrite-type circulator to forcibly supply microwaves to multiple power ports. .

In the figure, 11 is a heating chamber equipped with a main power feed port 12 and a sub power feed port 13, 14 is a main wave pipe that communicates with the heating chamber via the main power feed port 12, and the main wave pipe is coupled to one side. A hole 15 is bored. 16 is a sub-waveguide connecting the coupling hole 15 and the sub-power feeding port 13;
Reference numeral 7 denotes a ferrite type circulator disposed near the coupling hole 15 of the main wave pipe 14, and the circulator is connected to ferrite elements 18, 18 disposed near the coupling hole 15 of the main wave pipe 14 so as to face each other. It consists of ferrite elements 18, 18 and magnetic field generating devices (for example, electromagnets, etc.) 19, 19 provided to face each other, respectively. 20 is the main wave tube 14
It is a magnetron installed at one end of the.

In such a device, a magnetic field is applied by the circulator 17 in the direction in which the ferrite elements 18, 18 face each other. That is, when the above magnetic field is not applied to the ferrite elements 18, 18, the magnetron 2
The microwave from 0 is sent to the main power supply port 12 and the sub power supply port 1.
3 into the heating chamber 11, and when the magnetic field is applied to the ferrite elements 18, 18, the microwaves from the magnetron 20 are deflected by the magnetic field and are supplied to the heating chamber 11 only from the sub-power feeding port 13.
supplied within.

Therefore, by turning on and off the circulator 17, the microwave power feeding described above can be performed alternately, thereby obtaining a uniform electric field distribution within the heating chamber 11.

However, in order to obtain such a uniform electric field, the main power supply port 12 and the sub power supply port 13 must be placed at predetermined positions, that is, when the circulator 17 is turned on and when the circulator 17 is turned off, the heating chamber 11 is
The holes must be drilled in a position that prevents standing wave modes from coinciding with each other. Therefore, since the drilling position of the power supply port is fixed for the above-mentioned reason, the location of the infrared sensor, etc., which must be placed approximately in the center of the top surface of the heating chamber, overlaps with the drilling position of the power supply port. A problem arises when this happens.

Furthermore, since the standing wave mode differs depending on the amount of load in the heating chamber 11, it is very difficult to provide each power feed port at a position where the two standing wave modes do not always coincide regardless of the amount of load. Furthermore, since the circulator 17 is expensive, it is not practical due to the problem of high cost.

The present invention has been made in view of the above-mentioned problems, and is a high-frequency heating device that uniformizes the electric field in a heating chamber by changing the amount of microwaves fed from a plurality of power ports in an analog manner. We aim to provide the following. The present invention will be explained below based on Examples.

5 and 6 show an embodiment of the present invention,
21 is a heating chamber in which a main power feed port 22 and a sub power feed port 23 are formed; 24 is a pass-through TE10 mode main wave tube communicating with the heating chamber 21 via the main power feed port 22; and 25 is the main wave tube. The magnetron 26 is a cut-off waveguide that serves as a cut-off for the microwaves emitted from the magnetron 25, and one end of the cut-off waveguide is connected to the main waveguide 24. It communicates with the main waveguide 24 through a coupling hole 27 bored in one side, and the other end communicates with the heating chamber 21 through a sub-power feed port 23 . 28, 28... are dielectric resonators disposed within the cut-off waveguide 26, and among the dielectric resonators, the dielectric resonator 28A closest to the coupling hole 27 is connected to the motor 29 as a rotating means. The rotating surface is rotated so that it becomes parallel to the top surface of the heating chamber 21.

Next, the operating principle of this embodiment will be explained using FIG. 7.

In FIG. 7, reference numeral 31 denotes a TE10 mode pass-through first waveguide that propagates, for example, a microwave of frequency f, and this waveguide corresponds to the main waveguide 24 in FIG. 32 is a second waveguide that communicates with the first waveguide 31 through a communication hole 33 corresponding to the coupling hole 27 in FIG. It is cut-off and corresponds to the cut-off waveguide 26 in FIG. 34,
34... are dielectric resonators disposed within the second waveguide 32, and the dielectric resonator 34A disposed closest to the first waveguide 31 is driven to rotate parallel to the plane of the paper.

Normally, the second waveguide 32 does not propagate microwaves of frequency f traveling in the direction of arrow 35 in the figure.
However, there is evanescent energy that is reactive and decays exponentially near the coupling with the first waveguide 31. In the figure, the magnetic lines of force 36 of the microwave are indicated by dotted lines.

However, if the dielectric resonator 34 is appropriately placed inside the second waveguide 32 as shown in FIG. combine with At this time, the energy intensity coupled is between the communication hole 33 and the dielectric resonator 3 closest to the communication hole 33.
It is determined by the distance t from 4A, and is maximum when t=0. Furthermore, the above coupling strength is determined by the dielectric resonator 34.
It also changes depending on the coupling direction of A and the microwave. In other words, the height a, length b, and width c shown in Figure 8
When the dielectric resonator 40 of 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. Become.

Therefore, other resonators 34 and 3 except for the dielectric resonator 34A disposed closest to the first waveguide 31
4... is arranged so as to be most strongly coupled to the microwave traveling in the extending direction of the second waveguide 32, the second waveguide 32 becomes a band pass filter and the microwave coupled to the dielectric resonator 34A is propagate. Also,
Since the dielectric resonator 34A located near the communication hole 33 is rotating, its coupling amount changes in an analog manner, and therefore the amount of microwaves passing through the second waveguide 32 also changes in an analog manner.

In this embodiment, the frequency of the microwave emitted from the magnetron 25 is 2450 MHz, so the cut-off waveguide 26 has a width A of 2 cm so as to cut off the microwave. Further, the dielectric resonators 28, 28, .
11.5mm, width c = 6mm, b x c plane is the above motor 29
It is mounted perpendicular to the axis of rotation. The other dielectric resonators 28, 28... have a length a = 7.5 mm in the direction perpendicular to the bottom surface of the cut-off waveguide.
The length in the extending direction of the waveguide is b = 11.5 mm, the length in the width direction of the waveguide is c = 6 mm, and one of the b x c planes is the cut-off waveguide 26. is fixed to the bottom of the. Further, the shortest distance between the surfaces of the dielectric resonators 28 was set to 25 mm.

Therefore, in the high frequency heating device of this embodiment, when the magnetron 25 is oscillated and the motor 29 is driven to rotate the dielectric resonator 28A, the main power feed port 2
2 into the heating chamber 21, microwaves are also supplied from the sub-power feeding port 33 depending on the amount of coupling with the dielectric resonator 28A.

Also, at this time, the dielectric resonator 28A is connected to the motor 29.
Since the resonator 28A is rotationally driven by
The amount of microwave coupling changes in an analog manner, and therefore the amount of microwaves supplied from the main power supply port 22 and the sub power supply port 23 also changes in an analog manner, similar to when the microwaves in the heating chamber are stirred with a stirrer. The electric field distribution within the heating chamber becomes uniform.

FIG. 9 shows another embodiment of the present invention, and the difference from the first embodiment is that a pass-through auxiliary waveguide 31 is provided between the cut-off waveguide 26 and the auxiliary feed port 23 in the TE01 mode. This is because we have established the following. Note that the same parts as in FIG. 6 are given the same numbers.

In such a device, the microwave propagated from the cut-off waveguide 26 to the sub-waveguide 31 is transmitted through the sub-feed port 23.
The power is supplied to the heating chamber 21 through the main power supply port 22 and the sub power supply port 2 as in the first embodiment.
Since the amount of microwaves supplied from the heating chamber 21 changes analogously with the rotation of the dielectric resonator 28A rotated by the motor 29 (not shown in FIG. 9), the electric field distribution in the heating chamber 21 is uniform. Become.

In both of the apparatuses of the above-mentioned embodiments, the electric field is made uniform by changing the amount of microwave supplied from each power supply port in an analog manner, so each power supply port can be provided at an arbitrary position. In both of the above embodiments, a plurality of dielectric resonators 28 are disposed within the cut-off waveguide 26, but for example, the cut-off waveguide 26 may be shortened and the dielectric resonator 2 mounted on the rotating shaft of the motor 29 may be used.
It is also possible to use only 8A.

In addition, in this embodiment, there is one sub-power feeding port, but
The present invention is not limited to this, and by providing a plurality of cut-off waveguides, it is also possible to simultaneously supply microwaves from a plurality of power supply ports.

As is clear from the above explanation, in the high-frequency heating device of the present invention, the amount of microwaves supplied from the plurality of power supply ports is varied in an analog manner, so that the electric field distribution in the heating chamber is uniform, and the number of the plurality of power supply ports is arbitrary. This is very convenient in terms of design.

[Brief explanation of the drawing]

Figures 1 to 4 show conventional examples, where Figures 1 and 3 are side sectional views, Figures 2 and 4 are plan sectional views, and Figures 5 and 4 are side sectional views.
6 are a side sectional view and a plan sectional view showing an embodiment of the device of the present invention, FIG. 7 is a plan sectional view for explaining the operating principle of the present invention, and FIG. 8 is a dielectric resonator. FIG. 9 is a plan sectional view showing another embodiment. 21...Heating chamber, 22...Main power supply port, 23...
Sub-power feeding port, 24... Main waveguide, 26... Cut-off waveguide, 27... Coupling hole, 28, 28... Dielectric resonator, 29... Motor (variable means), 31...
...Sub waveguide.

Claims (1)

[Claims] 1. A heating chamber equipped with a main power supply port and at least one sub power supply port, a main waveguide that propagates microwaves in the heating chamber through the main power supply port and has at least one coupling hole; a cut-off waveguide that connects the sub-power feeding port and the coupling hole and serves as a cut-off for the microwave; a cut-off waveguide is arranged in the cut-off waveguide at a position capable of coupling with the evanescent energy of the microwave; dielectric resonator,
A high-frequency heating device comprising variable means for varying the coupling energy between the dielectric resonator and the evanescent energy. 2. A heating chamber equipped with a main power feed port and at least one sub power feed port, a main wave pipe that propagates microwaves into the heating chamber through the main power feed port and has at least one coupling hole, and a main wave pipe that propagates microwaves through the main power feed port and has at least one coupling hole. a cut-off waveguide that communicates with the main waveguide and is cut-off to the microwave; a dielectric resonator disposed within the cut-off waveguide at a position capable of coupling with the evanescent energy of the microwave; A high-frequency heating device comprising a variable means for varying the coupling energy between the dielectric resonator and the evanescent energy, and a sub-waveguide communicating the cut-off waveguide and the sub-power feeding port.