JPH08171986A - Microwave heating device - Google Patents

Abstract

PURPOSE: To operate two microwave radiation units at the same time without generating the interference with each other by forming a device so that the reflected wave of the microwave, which is radiated from one radiation unit, inside of a heating container does not enter the other radiation wave, of which deflected wave surface crossing the deflected wave surface of the former radiation unit, even in the case where the deflected wave surfaces of two microwave radiation units cross each other. CONSTITUTION: A power source transformer 4b drives magnetrons 1a, 1b, and the excited microwave is radiated inside of a heating container 5 by radiation units 3a, 3b through waveguides 2a, 2b. Since each magnetron 1a, 1b has the vertical and the horizontal components, even in the case where two magnetrons are excited at the same time, reflected wave of the microwave, which is radiated from the radiation unit 3a, inside of the heating container does not enter the other radiation unit 3b, of which deflected wave surface cross the deflected wave of the radiation unit 3a. As long as two magnetron units are normally operated, the two magnetron units can be operated without generating the interference with each other, and the synthesized output can be radiated inside of the heating container.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device using microwaves, and more particularly to a heating device using a plurality of microwaves.

[0002]

2. Description of the Related Art In a microwave heating apparatus, the object to be heated and the air do not have a uniform dielectric constant, so that the microwave applied to the object causes multiple reflection inside the container.
It is absorbed by the object after several re-incidents. When heating is performed using a plurality of magnetrons, the impedances of the magnetrons are mismatched due to load fluctuations such as mutual interference between the magnetrons due to the respective reflected waves. When this impedance mismatch occurs, the magnetron itself is heated and its output efficiency deteriorates.

Conventionally, an isolator for removing a reflected wave reflected from the load side is attached to the output part of the magnetron, or a microwave irradiating part is separately used for each container so that the magnetron does not interfere with each other. Was there.

Further, especially when the number of magnetrons is two, a half-wave rectified high voltage 2 for driving the magnetrons is used.
The output power is combined without being affected by the mutual interference between the magnetrons by shifting the phases of the pairs by 90 °, that is, by driving them by an intermittent transmission method in which they are combined so as not to overlap each other.

When two magnetrons are driven by this intermittent oscillation method, two sets of high-voltage rectified waveforms do not overlap each other, so that when one magnetron is oscillating, the other magnetron is in a non-operating state. Therefore, even if the microwave radiated from one magnetron is reflected inside the heating container and is incident on the other magnetron, it does not affect the non-operating magnetron. Therefore, in the case of two magnetrons, if each magnetron alone provides impedance matching and outputs normally, the two magnetrons are normally operated by the intermittent oscillation method without mutual interference.

The method of applying such a plurality of magnetrons to the heating device is a technique necessary for increasing the capacity of the heating device.

[0007]

However, in the method of using a plurality of magnetrons using the above-mentioned isolator, the product price becomes high.

If the microwave irradiator is separated from the container, the entire structure becomes large and uneven heating occurs.

On the other hand, the intermittent transmission method in which the phases of two sets of half-wave rectified high voltages are shifted by 90 ° is effective when the number of magnetrons is two, but cannot be applied when it is four, for example. A method of using 1 / 4-wave rectification instead of half-wave rectification is also possible, but in order to obtain the expected power (output) of the magnetron, the power supplied to the magnetron must be increased, Power saving cannot be achieved.

A first object of the present invention is to replace the above-mentioned intermittent transmission method when a plurality of magnetrons are used,
It is to provide a heating device in which mutual interference between magnetrons is reduced.

A second object of the present invention is to provide a heating device having a simple structure when four or more magnetrons are provided.

[0012]

In order to solve the above-mentioned problems, the present invention relates to a method of combining two sets of magnetrons so that the linearly polarized waves to be irradiated are orthogonal to each other (orthogonal polarized wave irradiation method). did.

Specifically, a heating chamber for arranging an object to be heated, a first microwave irradiating means for irradiating the heating chamber with a first microwave, and a second microwave for irradiating the heating chamber. And a second microwave irradiating means, wherein the first microwave irradiating means and the second microwave irradiating means are linearly polarized waves of the first microwave and the second microwave. Were radiated so as to be orthogonal to each other.

Further, according to the present invention, when four magnetrons are driven, an intermittent oscillation method which has been conventionally used (two sets of high-voltage half-wave rectified high voltage driving the magnetrons are shifted in phase by 90 ° and do not overlap each other. And a method of irradiating the orthogonally polarized wave described above are used together as a driving method of the magnetron. In other words, two magnetrons that irradiate with the same linear polarization are driven by intermittent transmission,
It is assumed that the polarized waves are orthogonal to this and the other two magnetrons are driven by intermittent transmission.

Specifically, it comprises a heating chamber for arranging an object to be heated, and a plurality of microwave irradiating means for irradiating the heating chamber with microwaves. In the case of having first and second microwave irradiation means for irradiating with a driving voltage and third and fourth microwave irradiating means for irradiating with a second driving voltage, and irradiating microwaves in accordance with the cycle The irradiation was performed so that the linearly polarized waves of the respective microwaves were made orthogonal to each other.

Further, the one-unit heating container has a symmetrical structure in the front-rear direction and the left-right direction, and each of the four microwave irradiating parts is provided with directivity so that they are installed at positions such that their mutual positional relationships are the same. It was decided to combine by changing the irradiation direction for each °.

[0017]

When the polarization planes of the two microwave irradiators are orthogonal to each other, even if the magnetrons connected to the two microwave irradiators are excited at the same time, the reflected waves of the microwaves radiated from one of the irradiators in the heating container are It does not enter the other irradiation section whose polarization plane is orthogonal. Therefore, as in the above case, these two sets can be operated at the same time without mutual interference if the individual magnetrons operate normally.

Further, by using both the intermittent oscillation method and the orthogonal polarization irradiation method in combination, two magnetrons that irradiate with the same linearly polarized wave are driven by intermittent oscillation so as not to cause mutual interference. If two other magnetrons that are orthogonal to each other are driven so that there is no mutual interference due to intermittent oscillation,
Since the polarizations of the former two magnetrons and the latter two magnetrons are orthogonal to each other, these four pairs can be operated simultaneously without mutual interference. In addition, the four microwave irradiators having the same directivity are installed at the positions where the mutual positional relationship is the same in the heating container having a symmetrical structure in the front-rear and left-right directions,
When the irradiation directions are changed every 90 ° and combined, it is possible to expect the effect of rotating the microwave irradiation part, and it is possible to irradiate the microwave so as to reduce the unevenness inside the heating container. Become. In the past, by rotating the microwave irradiation unit, uneven heating was eliminated.
Considering the reflection of microwaves inside the container, the distance at which the microwaves reach the inner wall of the container changes, causing a mismatch in the impedance of the magnetron. That is, when the microwave irradiation unit is rotated, the magnetron itself is heated due to the impedance mismatch of the magnetron.

However, as in the present invention, if four magnetrons are provided in the container and each magnetron has directivity to eliminate uneven heating, the distance until the microwave reaches the inner wall of the container is constant. Therefore, the conventional magnetron itself is not heated. Also, of course, a motor for rotating the microwave irradiator is unnecessary.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment which is a basic constitution of a microwave heating apparatus of the type which radiates microwaves from two magnetrons by orthogonal linearly polarized waves according to the present invention. (A) is a plan view and (b) is a side view.

The heating device comprises magnetrons 1a, 1b,
The waveguides 2a and 2b, the irradiation units (antennas) 3a and 3b, the power transformers 4a and 4b, the heating container 5, and the like.

The power transformers 4a and 4b drive the magnetrons 1a and 1b, and the excited microwaves are guided by the waveguide 2
The inside of the heating container 5 is irradiated from the irradiation units (antennas) 3a and 3b via a and 2b. Irradiator (antenna) 3a,
The waveguides 2a and 2b are mounted orthogonally on the heating container 5 in order to make the directions 6a and 6b of the linearly polarized waves emitted from 3b orthogonal. The microwave is applied in the direction of the antenna shown in FIG. 1 (b). The arrow shown in FIG. 1 (a) indicates whether the microwave component to be irradiated has a vertical component or a horizontal component. , Magnetron 1a, 1
Since each of b has a vertical component and a horizontal component, even if two magnetrons are excited at the same time, the reflected wave of the microwave irradiated from the irradiation unit 3a inside the heating container is It does not enter the irradiation unit 3b. In other words, since an antenna that irradiates with linearly polarized waves can receive only the same polarized wave, when the polarization planes of the two sets of microwave irradiation units are made orthogonal to each other as shown in FIG. Even if excited at the same time, the reflected wave from the heating container of the microwave radiated from one irradiation unit does not enter the other irradiation unit, and if each of the two magnetrons operates normally, 2 Both can be operated at the same time without mutual interference,
The combined output can be applied to the inside of the heating container.

FIG. 2 shows the structure of the irradiation unit. This is a structure in which a waveguide is provided with a slot as an irradiation unit (antenna) for irradiating linearly polarized waves. FIG. 2 (a) shows an embodiment in which one slot is provided, and the microwave is simply irradiated in the opening direction. In addition, 11a is a magnetron, 3 is a slot, and 7 is a microwave output from the magnetron 11a.

When the width t of the slot shown in FIG. 2 is set shorter than the length s of the slot, an electric field is excited on the slot in a direction orthogonal to the length s direction, and a linear polarization vibrating in this direction is generated. Waves are emitted. As a result, the linearly polarized microwave shown in FIG. 1 is realized.

Next, the case where four magnetrons are used in the heating device will be described. In the present invention, four magnetrons are driven by combining the orthogonal polarization irradiation method and the intermittent oscillation method. FIG. 3 (a) is a plan view of the microwave heating apparatus of the present invention, FIG. 3 (b) is a side view, and FIG. 3 (c) shows a combination of half-wave rectified power supply waveforms used in the intermittent oscillation method.

In FIG. 3, irradiation parts (antennas) for irradiating with the same linear polarized wave are designated as 3a and 3c, and irradiation parts (antennas) for irradiating with polarized waves orthogonal to this are designated as 3b and 3d. For these four irradiation units (antennas), irradiation units (antennas) driven by the same half-wave rectified waveform are defined as 3a and 3b, and irradiation units (antennas driven by half-wave rectified waveforms that are 90 ° out of phase with each other). ) Are 3c and 3d.

The combination of 3a and 3b can be excited without mutual interference because the polarized waves are orthogonal to each other.
The combination of d can also be excited without mutual interference. Since these two sets oscillate intermittently, all four irradiation units (antennas) can be excited without mutual interference, and the combined output can be irradiated inside the heating container.

It is preset for each irradiation unit whether to irradiate the vertical component microwave or the horizontal component microwave, and which irradiation unit is driven by the same half-wave rectified waveform is selected. This means that any combination may be used as long as the microwaves irradiated at the same time are not the same component (horizontal, vertical).

FIG. 4 shows a microwave heating device of the present invention in which the orthogonal polarization irradiation method and the intermittent oscillation method are combined to drive four magnetrons. An example in which the wave irradiator is installed by changing the irradiation direction every 90 ° will be shown. In this embodiment, it is possible to expect the effect of rotating the microwave irradiator, and it is possible to irradiate the microwave so that the unevenness in the heating container is reduced.

FIG. 2B shows an embodiment for giving directivity to the irradiation part.

In FIG. 2 (b), by providing a plurality of slots, the microwave is excited in each slot and has a directivity. That is, the irradiation direction from the slots was changed by changing the number of slots and the interval u of the slots.

As described above, if four magnetrons are provided in the container and each magnetron has directivity to eliminate uneven heating, the distance until the microwave reaches the inner wall of the container becomes constant, and the conventional When the microwave irradiation unit is rotated, the magnetron itself is not heated due to the impedance mismatch of the magnetron. Also, of course, a motor for rotating the microwave irradiator is unnecessary.

FIG. 5 shows an embodiment in which the heating device is further enlarged. In this heating apparatus, the orthogonal polarization irradiation method of the present invention and the intermittent oscillation method are combined to drive four magnetrons as one unit, and the entire magnetron is divided into multiples of these four wire meshes. An example is shown, which is separated by a manufacturing partition (punching plate). As a result, since the interiors of the partitions are excited without mutual interference between the magnetrons, the partitions can prevent the units from interfering with each other, and irradiation can be performed with the combined output as a whole. Note that the metal mesh partition (punching plate) shields microwaves, but water vapor and the like generated during heating can move between units, causing problems in heating (circulation of heat, etc.). There is no configuration.

Although a magnetron has been mainly described as a microwave irradiating means in the above description, the present invention is not limited to this.

[0036]

As described above, according to the present invention, it is possible to provide a heating device in which mutual interference between magnetrons is reduced when a plurality of magnetrons are used.

Further, when four or more magnetrons are provided, it is possible to provide a heating device having a simple structure which uses both the intermittent oscillation system and the orthogonal polarization irradiation system. As a result, it is possible to arrange four or more magnetrons, so that it is possible to cope with an increase in size of the heating device. Further, since there is no mutual interference between the magnetrons, if the impedances of the individual magnetrons are matched and output normally, the four main forces can be combined as they are.

[Brief description of drawings]

FIG. 1A is a plan view of a microwave heating apparatus using orthogonal linearly polarized waves of the present invention. FIG. 1B is a side view of a microwave heating apparatus using orthogonal linearly polarized waves of the present invention.

FIG. 2A is an example of a microwave irradiation unit. FIG. 2B is an example of a microwave irradiation unit.

FIG. 3A is a plan view of a microwave heating apparatus that combines the orthogonal polarization irradiation method and the intermittent oscillation method of the present invention. FIG. 3B is a microwave heating that combines the orthogonal polarization irradiation method and the intermittent oscillation method of the present invention. Side view of device (c) Waveform diagram of half-wave rectified voltage used for intermittent oscillation method

FIG. 4 is an example of a case where a microwave irradiator is provided with directivity.

FIG. 5: One embodiment in which a microwave heating device is provided with a partition

[Explanation of Codes] 1a, 1b, 1c, 1d, 11a ... Magnetrons 2a, 2b, 2c, 2d ... Waveguides 3a, 3b, 3c, 3d ... Microwave irradiation parts 4b, 4c ... Power transformer 5 ... Heating container 6 ... Slot 7 ... Polarized wave excitation direction 8 ... Microwave irradiation part irradiation direction 9 ... Heating chamber internal partition

Claims (7)

[Claims] 1. A heating chamber for arranging an object to be heated, a first microwave irradiating means for irradiating the heating chamber with a first microwave, and a second irradiating the heating chamber with a second microwave. The microwave irradiating means, and the first microwave irradiating means and the second microwave irradiating means make the linearly polarized waves of the first microwave and the second microwave orthogonal to each other. The microwave heating device is characterized by irradiating the microwave. 2. The microwave irradiating means is composed of a magnetron and a waveguide including a microwave irradiating section for irradiating the heating chamber with microwaves, and the linear polarization is obtained by feeding power to the waveguides. The microwave heating device according to claim 1, wherein a wave is generated. 3. The microwave irradiation section is an irradiation opening provided in the waveguide.
Microwave heating device described. 4. A heating chamber for arranging an object to be heated, and a plurality of microwave irradiating means for irradiating the heating chamber with microwaves, wherein the plurality of microwave irradiating means use a first drive voltage. Irradiating first and second microwave irradiating means, and third and fourth microwave irradiating means for irradiating with a second drive voltage, and when irradiating microwaves according to the drive voltage, respectively, The microwave heating device is characterized in that the linearly polarized wave of the microwave is irradiated so as to be orthogonal. 5. The microwave irradiating means is composed of two magnetrons for irradiating with the same linearly polarized wave and two magnetrons for irradiating with a linearly polarized wave orthogonal to the same, and the first and second The microwave heating device according to claim 4, wherein the driving voltage is generated by a combination of two sets of half-wave rectified waveforms. 6. The microwave heating apparatus according to claim 4, wherein the microwave irradiating means has directivity to the microwaves to be radiated. 7. The micro according to claim 4, wherein the four microwave irradiating means are one unit, and a plurality of the units are provided by attaching a partition for shielding the microwave. Wave heating device.