WO2020090812A1

WO2020090812A1 - Microwave device

Info

Publication number: WO2020090812A1
Application number: PCT/JP2019/042358
Authority: WO
Inventors: 博道小田島; 正岡本
Original assignee: 株式会社Ｐｍｔ
Priority date: 2018-10-30
Filing date: 2019-10-29
Publication date: 2020-05-07
Also published as: JP2020072354A

Abstract

Provided is a microwave device that can suppress a performance variation by means of a simple structure. This microwave device 100 includes a microwave generator 10; a power feeding path unit 20 which guides microwaves; and a resonator 30 which includes therein a cavity 30a into which the microwaves are introduced. The power feeding unit 20 includes a center conductor 21, an insulator and an external conductor. In the cavity 30a, an electromagnetic field of the TM010 mode or TM110 mode is excited. A termination unit of the external conductor is electrically connected to one wall part among an upper wall part and a lower wall part of the resonator 30. The center conductor 21 includes an introduction unit 21a that introduces the microwaves into the cavity 30a. The introduction unit 21a protrudes inside the cavity 30a by penetrating through a hole 32a formed in the one wall part in a state of being electrically insulated from the one wall part to, and extends in parallel to a central axis O around an inner surface 30b of the resonator 30.

Description

Microwave equipment

The present invention relates to a microwave device that irradiates a microwave to subject an object to processing such as heating and accelerating a chemical reaction.

In recent years, it has been found that high-frequency energy of microwaves promotes a chemical reaction of an object (substance), and in various fields such as biochemistry, industry, science, and medicine, a device using microwaves (microwave Equipment) is increasing.

As such a microwave device, the one described in Patent Document 1 is known. The microwave device described in Patent Document 1 includes a microwave generator that generates (oscillates) microwaves and outputs the microwaves, a resonator having a cavity inside, and a microwave generator and a resonator. A coaxial feed line (hereinafter, referred to as a coaxial cable) that is connected between them and guides the microwave output from the microwave generator to the resonator. In this microwave device, the microwave guided to the resonator by the coaxial cable is introduced into the cavity inside the resonator via the loop antenna. Then, in this microwave device, the microwave is resonated in the cavity to generate a single mode electric field, and the microwave heats the object supplied into the cavity. In this microwave device, as described above, the coaxial line system using the coaxial cable is adopted as a system for guiding and coupling the microwave output from the microwave generator to the resonator. In general, in the coaxial line system, it is difficult to guide microwaves in a wide output range from low output to high output as in the waveguide system. However, the coaxial line method is suitable for low output applications (for example, about 100 W or less) because it can reduce the size and cost of the device as compared with the waveguide method.

JP, 2006-338895, A

Here, in the microwave device adopting the conventional coaxial line system, like the microwave device described in Patent Document 1, microwaves are introduced through a loop antenna provided in the resonator to generate microwaves. It was configured to couple to a resonator. The loop antenna described in Patent Document 1 is a conductor connected to a coaxial cable via a connector attached to the outer surface of the resonator, and its end portion is U-shaped so as to contact the inner surface of the resonator. It is formed into a shape. The loop antenna is not limited to the U-shape disclosed in Patent Document 1, but an L-shaped bent antenna or a ring antenna is also known. As a method of constructing these loop antennas inside the resonator, there are a method of forming the loop antenna inside the resonator and a method of forming the loop antenna outside the resonator. Specifically, in the case of molding in a resonator, a small hole through which a thin wire as a conductor can be inserted was opened in the side wall of the resonator, and a part of the conductor was inserted into the resonator through the small hole. After that, a part of the conductor is bent into a predetermined shape such as a U shape, an L shape, or a ring shape in the resonator to form the loop antenna. When molding outside the resonator, the loop antenna having the predetermined shape is formed outside the resonator in advance, and a large opening through which the loop antenna can be inserted is opened in the sidewall of the resonator and formed in advance. The loop antenna is inserted into the resonator through the large opening.

However, when forming a loop antenna in a resonator, it is difficult to construct a loop antenna of the same shape with good reproducibility in a narrow resonator. Also, when molding the loop antenna outside the resonator, the loop antenna is accurately positioned inside the resonator after it is inserted into the resonator through the large opening on the sidewall of the resonator. It is difficult to accurately adjust the posture of the loop antenna such as the angle of the loop antenna with respect to the center axis of the cavity. Therefore, in the microwave device described in Patent Document 1, since the shape of the loop antenna and the position and orientation of the loop antenna in the resonator easily vary from device to device, the degree of coupling of the microwave with the resonator also varies from device to device. Easy to vary. As a result, the performance between devices is likely to vary, and it is difficult to supply a microwave device having a predetermined performance with a simple structure and good reproducibility.

The present invention has been made in view of the above problems, and an object thereof is to provide a microwave device capable of suppressing performance variations with a simple structure.

According to one aspect of the present invention, a microwave device includes a microwave generator that generates and outputs a microwave, a power feeding path portion that guides the microwave output from the microwave generator, and the power feeding path portion. A resonator having therein a cavity into which the microwave guided by the above is introduced, and an object supplied into the cavity is heated by the microwave. The power feeding path portion has a center conductor, an insulator covering the center conductor, and an outer conductor covering the insulator, and extends coaxially. An electromagnetic field of TM010 mode or TM110 mode showing a uniform electric field distribution in the direction of the central axis of the cavity is excited in the cavity of the resonator due to the resonance of the microwave. The terminal portion of the outer conductor is electrically connected to one of the upper wall portion and the lower wall portion that closes both ends of the cavity in the central axis direction of the cavity. The center conductor has an introduction part for introducing the microwave into the cavity. The introduction portion penetrates a hole formed in the one wall portion in a state of being electrically insulated from the one wall portion and projects into the cavity, and an inner surface of the resonator. In the vicinity of, it extends parallel to the central axis.

According to the microwave device of the one aspect, a microwave generator that generates and outputs a microwave, a power feeding path portion that guides the microwave output from the microwave generator, and a power feeding path portion. A TM010 mode or a TM110 mode having a cavity into which the guided microwave is introduced and showing a uniform electric field distribution in the direction of the central axis of the cavity due to the resonance of the microwave in the cavity. A resonator for exciting an electromagnetic field of the microwave generator for heating an object supplied into the cavity by the microwave. The introducing portion to be introduced into the body penetrates one wall portion of the upper wall portion and the lower wall portion of the resonator and protrudes into the cavity, and is near the inner surface of the resonator. Parallel to the central axis, that is, extends in a straight line. Therefore, the introduction part for introducing the microwave into the cavity is constructed with a simple structure without performing a special molding process, and the introduction part having the same shape is constructed with good reproducibility. Further, since the introduction portion only extends linearly, the hole through which the introduction portion penetrates the one wall portion is, for example, matched with the outer diameter of the insulator of the power feeding path portion. The diameter may be small, and the position of the introduction portion (a part of the central conductor) in the cavity can be easily determined by fitting the end portion of the insulator into the small diameter hole. As a result, in the microwave device according to the one aspect, the shape and the position of the introducing portion forming the portion corresponding to the conventional loop antenna and the position and the posture of the introducing portion in the resonator (specifically, the cavity) are different. It is not likely to vary from device to device, and the degree of coupling of microwaves with the resonator is unlikely to vary from device to device. Therefore, variations in performance between devices are unlikely to occur, and a microwave device having a predetermined performance can be supplied with a simple structure and good reproducibility.

In this way, it is possible to provide a microwave device that can suppress performance variations with a simple structure.

Also, an electromagnetic field of TM010 mode or TM110 mode is excited in the cavity. In this mode, the electric field is uniform in the direction of the central axis of the cavity, so that the electric field is constant in the direction of the central axis (stretching direction). The hole for penetrating the introduction portion is formed in one of the upper wall portion and the lower wall portion that closes both ends of the cavity in the central axis direction. Therefore, the microwave device according to the one aspect has a structure in which the electric field distribution in the cavity is not easily affected by the opening of the hole. In this respect, in the conventional microwave device, when inserting the preformed loop antenna into the resonator as described above, a large opening must be opened in the side wall of the resonator, and the electric field distribution is The structure is easily affected by the large opening formed in the side wall. In addition, in the conventional microwave device, it is necessary to add an auxiliary metal component so that the microwave does not leak from the gap between the inner wall surface of the hole of the large opening formed in the side wall of the resonator and the loop antenna. Therefore, the electromagnetic field distribution is likely to be disturbed in the cavity due to the added metal parts. On the other hand, in the microwave device according to the one aspect, since it is not necessary to open a large opening in the side wall of the resonator, the occurrence of disturbance in the electromagnetic field distribution due to the metal component can be prevented or suppressed. Further, in the microwave device according to the one aspect, the distal end portion of the introduction portion extending in the cavity is brought into contact with the other wall portion of the upper wall portion and the lower wall portion, or the distal end portion of the introduction portion. The introductory portion can be easily and stably supported by the two-point support simply by sandwiching the insulator between the upper wall portion and the other wall portion of the lower wall portion. In the microwave device according to the one aspect, since the hole can be made smaller than the large opening described above which is required when the conventional loop antenna is formed outside the resonator, the microwave through the hole is used. Wave leakage is extremely low and can be easily suppressed or prevented.

It is a schematic structure figure of a microwave device concerning a 1st embodiment of the present invention. It is an expanded sectional view of the A section shown in FIG. FIG. 2 is a sectional view taken along the line BB shown in FIG. It is a graph for demonstrating the apparatus characteristic of the said microwave apparatus, and is a graph at the time of making toluene into a heating object. 6 is a graph for explaining a change in the device characteristic when the target object is changed. 6 is a graph for explaining changes in the device characteristics when the height of the cavity of the microwave device is changed. 6 is a graph for explaining a change in the device characteristic when the minimum separation distance between the inner surface of the resonator of the microwave device and the introduction portion (antenna) is changed. It is a schematic block diagram of the microwave device which concerns on 2nd Embodiment of this invention. It is a graph for demonstrating the change of a device characteristic when changing the length (projection length) of an antenna in the microwave device concerning a 2nd form. It is a graph for demonstrating the change of a device characteristic when the said target object is changed in the microwave device which concerns on 2nd Embodiment. It is sectional drawing for demonstrating the modification of the introduction part of the microwave device which concerns on each embodiment. It is a schematic block diagram for explaining an example in the case where a plurality of microwave output units which consist of a microwave generator and a feed route part are provided in a microwave device concerning each embodiment. FIG. 13 is a cross-sectional view taken along the line CC of FIG. 12. It is sectional drawing for demonstrating the modification of the cavity of the microwave device which concerns on each embodiment. It is a principal part sectional view for demonstrating the modification of the electric power feeding route part (coaxial cable) of the microwave apparatus which concerns on each embodiment. It is a principal part sectional drawing for demonstrating the modification of the resonator of the microwave device which concerns on each embodiment. It is a figure for demonstrating an example at the time of providing the mechanism which adjusts the length of the antenna in the introduction part in the microwave device concerning a 2nd embodiment. It is a figure for demonstrating the example at the time of providing the mechanism which adjusts the substantial length which functions as an antenna in an introduction part in the microwave device which concerns on 2nd Embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a microwave device 100 according to the first embodiment of the present invention. In FIG. 1, a microwave device 100 includes a microwave generator 10, a power feeding path unit 20, a resonator 30, a flow pipe 40, a power monitor 50, and a control unit 60, and an object is a microwave. It is a device for heating by. In this embodiment, the object is a liquid. In addition, below, the said target object is called a heating target object.

In the present embodiment, the microwave device 100 is a flow-type device that can heat-treat a liquid as a heating target that flows so as to pass through the resonator 30.

The microwave generator 10 generates and outputs microwaves. The microwave generator 10 is configured to be able to sweep the microwave frequency (oscillation frequency) within a predetermined sweep range, for example. The microwave generator 10 is specifically configured to include a variable frequency oscillator 11, a variable attenuator 12, and an amplifier 13. The variable frequency oscillator 11 outputs microwaves, and is composed of, for example, a voltage controlled oscillator (VCO). The variable frequency oscillator 11 is configured to be able to sweep the oscillation frequency within the sweep range of 2.4 GHz to 2.5 GHz, which is the ISM frequency band, by changing the applied voltage. The variable attenuator 12 variably attenuates the power of the microwave input from the variable frequency oscillator 11. The amplifier 13 amplifies the power of the microwave input from the variable attenuator 12. The control unit 60 controls the oscillation frequency and power of the microwave oscillated by the variable frequency oscillator 11 and the attenuation rate of the variable attenuator 12. As a result, the microwave generator 10 outputs the microwave for entering the resonator 30 with a predetermined incident power P0. The microwave generator 10 is normally configured to be able to sweep in the ISM frequency band, but may be configured to be capable of sweeping in a slightly wider range than the ISM frequency band, if necessary.

FIG. 2 is an enlarged cross-sectional view of part A shown in FIG. The power feeding path unit 20 guides the microwave output from the microwave generator 10 with a predetermined incident power P0 to the resonator 30. The power feeding path portion 20 has a center conductor 21, an insulator 22 that covers the center conductor 21, and an outer conductor 23 that covers the insulator 22 and extends coaxially. Specifically, the power feeding path portion 20 is made of a coaxial cable in this embodiment. The center conductor 21 is made of a single copper wire material that extends in one direction and serves as the center material of the power feeding path portion 20. The insulator 22 is made of a plastic material such as polyethylene that extends coaxially with the center conductor 21 so as to cover the outer periphery of the center conductor 21, and is a member that electrically insulates the center conductor 21 and the outer conductor 23. That is, the insulator 22 is formed in a tubular shape. The outer conductor 23 is composed of a plurality of copper wire rods that are thinner than the central conductor 21. The outer conductor 23 is formed by braiding several layers of the copper wire material so as to cover the outer periphery of the cylindrical insulator 22. The outer periphery of the outer conductor 23 is covered with a protective film 24. One end of the power feeding path 20 is connected to the microwave generator 10, and the other end of the power feeding path 20 is connected to the resonator 30. Specifically, the microwave output from the microwave generator 10 at a predetermined incident power P0 is guided to the resonator 30 via the isolator 14 and the directional coupler 15 provided on the power feeding path portion 20. Get burned. Here, since a part of the microwave guided to the resonator 30 by the power feeding path portion 20 is not incident into the resonator 30 but reflected, it is incident into the resonator 30 (specifically, a cavity 31 described later). The net incident power P1, which is the net microwave power, is smaller than the microwave incident power P0 output from the microwave generator 10. Therefore, the object to be heated can be efficiently heated by minimizing (that is, matching) the reflection of the microwaves from the resonator 30. In this embodiment, the reflected wave is absorbed by the non-reflecting terminator 16 by the action of the isolator 14. As the coaxial cable forming the power feeding path portion 20, a semi-rigid type cable described later in which the outer conductor 23 is a metal (for example, copper) cylindrical tubular body and the protective film 24 is omitted is used. May be. The structure and the like of the connection portion of the power feeding path portion 20 to the resonator 30 will be described in detail later. Further, in the present embodiment, only one microwave generator 10 is provided, and the power feeding path portion 20 also forms one path.

3 is a sectional view taken along the line BB shown in FIG. The resonator 30 internally has a cavity 30a into which the microwave guided by the power feeding path section 20 is introduced, and generates a single-mode electric field in the cavity 30a by the resonance of the microwave. As shown in FIGS. 1 and 3, in this embodiment, the cavity 30a is formed in a columnar shape. An electromagnetic field of TM010 mode exhibiting a uniform electric field distribution in the direction of the central axis O of the cavity 30a is excited in the cavity 30a by the resonance of microwaves. The liquid as the heating target is supplied into the cavity 30a. In the present embodiment, the liquid as the heating target is supplied into the cavity 30a by flowing through the cavity 30a through the circulation pipe 40 as described later.

Specifically, the resonator 30 includes a cylindrical tubular body 31 extending in one direction, an upper wall portion 32 that closes an upper end side opening of the tubular body 31, and a lower wall that closes a lower end side opening of the tubular body 31. And a part 33. In other words, the tubular body 31 constitutes a side wall portion of the resonator 30, and the upper wall portion 32 and the lower wall portion 33 have both ends in the central axis direction of the cavity 30a of the resonator 30 (that is, the center of the cylindrical cavity 30a). Both ends of the axis O in the stretching direction are closed. For example, the tubular body 31 is made of an aluminum member, and the upper wall portion 32 and the lower wall portion 33 are made of aluminum flat plate members, which are opposed to each other and are formed in a circular shape. The upper wall portion 32 and the lower wall portion 33 are fixed to the ends of the tubular body 31 by bolts (not shown) or the like (not shown). In this way, a cylindrical cavity 30a (in other words, an irradiation chamber) is formed in the housing formed by assembling the cylindrical body 31 as the side wall portion, the upper wall portion 32, and the lower wall portion 33. In the case of the present embodiment, the center axis O of the cavity 30a coincides with the cylinder center axis extending to the center of the cylinder 31. Further, the central axis O coincides with a line connecting the radial center of the circular upper wall portion 32 and the radial center of the circular lower wall portion 33.

The circulation pipe 40 is a pipe that is disposed so as to penetrate the cavity of the resonator 30 and that circulates a liquid as a heating target. In the present embodiment, the flow pipe 40 is made of, for example, a flexible pipe made of borosilicate glass having a spiral portion 41 extending in a spiral shape. The flow tube 40 has the center axis O of the cavity 30a as the spiral center axis. That is, the flow pipe 40 is arranged so that the spiral central axis thereof coincides with the central axis O of the cavity 30a. Further, both end portions of the flow pipe 40 linearly extend along the central axis O of the cavity 30a. The flow tube 40 is positioned with respect to the resonator 30 by supporting both end portions thereof on the upper wall portion 32 and the lower wall portion 33. The liquid as a heating target, which is pressure-fed by a pressure-feeding pump (not shown), circulates from one end side to the other end side of the flow pipe 40, and is heat-treated by microwaves in the cavity 30a during this flow. .. In this way, the microwave generator 10, the power feeding path portion 20, the resonator 30, and the flow tube 40 are heated by the microwave to heat the liquid as the heating target, which is supplied into the cavity 30a. The microwave device 100 is configured.

The power monitor 50 measures the electromagnetic field intensity (electric field or magnetic field intensity) in the resonator 30, and is attached to, for example, the sidewall of the resonator 30 (in other words, the cylindrical body 31). A signal indicating the measurement result of the electromagnetic field strength measured by the power monitor 50 is input to the control unit 60.

The control unit 60 controls the operation of the microwave generator 10. For example, a signal from the power monitor 50 is input to the control unit 60, and a measurement result of the temperature of a liquid as a heating target measured by a temperature sensor (not shown) is input to perform optimum heating processing. The operation of the microwave generator 10 is controlled to be performed. The temperature of the liquid flowing through the flow pipe 40 has a distribution that gradually rises from the upstream side to the downstream side by the irradiation of microwaves. It is assumed that the temperature sensor is arranged so as to be able to measure the temperature of the liquid flowing through the downstream side portion of the flow pipe 40 (for example, the portion on the upper wall portion 32 side in FIG. 1) in the resonator 30 as a representative temperature. .. Specifically, the control unit 60 controls the voltage applied to the variable frequency oscillator 11 of the microwave generator 10 based on the signal from the power monitor 50, for example, so that the microwave generator 10 outputs the voltage. It is possible to execute automatic frequency adjustment control for automatically adjusting (matching) the oscillation frequency f of the microwave to the resonance frequency F of the resonator 30. More specifically, as the frequency automatic adjustment control, the control unit 60 sets the oscillation frequency f at which the intensity of the signal from the power monitor 50 is the largest within the sweep range of the oscillation frequency f as the actual frequency of the resonator 30. The oscillation frequency f is automatically adjusted to the resonance frequency F by detecting the resonance frequency F and controlling the voltage applied to the variable frequency oscillator 11 so as to oscillate the resonance frequency F. Although not shown, a reflected wave power monitor for measuring the power intensity of the reflected wave reflected from the resonator 30 toward the microwave generator 10 may be provided. In this case, the control unit 60 may automatically adjust the oscillation frequency f to the resonance frequency F based on the signal indicating the measurement result of the power intensity measured by the power monitor for reflected waves. The control unit 60 has a function of automatically adjusting (tuning) the oscillation frequency f to the resonance frequency F, a function of controlling the output of the microwave generator 10 to a predetermined value, and a directional coupler. It may have a function of detecting the reflected power detected at 15 and automatically adjusting the oscillation frequency f to the resonance frequency F or controlling the output level to a predetermined value according to the signal.

Next, the structure of the connection portion of the power feeding path portion 20 to the resonator 30 will be described in detail with reference to FIGS. 1 to 3.

The terminal portion of the outer conductor 23 in the power feeding path portion 20 is electrically connected to one of the upper wall portion 32 and the lower wall portion 33. In the present embodiment, as shown in FIG. 2, the one wall portion is the upper wall portion 32, and the end portion of the outer conductor 23 is electrically connected to the upper wall portion 32. In the following description, the one wall portion is described as the upper wall portion 32, but the present invention is not limited to this, and the one wall portion may be the lower wall portion 33.

Further, the center conductor 21 of the power feeding path portion 20 has an introduction portion 21a for introducing microwaves into the cavity 30a. The introduction portion 21a penetrates through the hole 32a formed in the upper wall portion 32 as the one wall portion in a state of being electrically insulated from the upper wall portion 32 and projects into the cavity 30a, and It extends parallel to the central axis O in the vicinity of the inner side surface 30b of the resonator 30 (in other words, the inner peripheral surface of the cylindrical body 31). Here, the inner side surface 30b of the resonator 30 is specifically the inner peripheral surface of the cylindrical body 31 and is exposed to the cavity 30a as a space.

Specifically, the hole 32a has, for example, an inner diameter matching the outer diameter of the insulator 22 and extends parallel to the central axis O. The terminal portion of the outer conductor 23 is in contact with the peripheral portion of the hole 32a on the upper surface of the upper wall portion 32, and is electrically connected and fixed to the peripheral portion by soldering or the like. Further, the terminal end portion of the insulator 22 projects below the terminal end portion of the outer conductor 23 by the wall thickness of the upper wall portion 32, for example. The end portion of the center conductor 21 projects further downward than the end portion of the insulator 22. Further, the power feeding path portion 20 is positioned with respect to the resonator 30 by, for example, fitting the insulator 22 into the hole 32a. The introduction portion 21a is electrically and reliably insulated from the upper wall portion 32 by the insulator 22, for example.

In this way, the hole 32a formed in the upper wall portion 32 penetrates the upper wall portion 32 in an electrically insulated state to project into the cavity 30a, and the inner surface 30b of the resonator 30. Introducing part 21a extending parallel to central axis O is formed in the vicinity of. In addition, below, the part of the introduction part 21a that projects into the cavity 30a is called an antenna, and the protruding length of this antenna is called the length L of the antenna.

In the present embodiment, the distal end portion 21a1 of the introduction portion 21a is electrically connected to the lower wall portion 33, which is the other wall portion of the upper wall portion 32 and the lower wall portion 33, as shown in FIG. There is. In the present embodiment, the distal end portion 21a1 of the introduction portion 21a is electrically connected to the lower wall portion 33 by abutting and contacting the lower wall portion 33 as the other wall portion. Therefore, the height H of the cavity 30a (in other words, the distance between the upper wall portion 32 and the lower wall portion 33, or the columnar cavity height) is equal to the length L of the antenna of the introduction portion 21a. I am doing it. The tip portion 21a1 of the introduction portion 21a contacts the upper surface of the lower wall portion 33, whereby the tip portion 21a1 of the introduction portion 21a is electrically connected to and supported by the lower wall portion 33.

In the present embodiment, the minimum separation distance G between the introduction portion 21a (specifically, the antenna) and the inner side surface 30b of the resonator 30 is set to a value of 5% or less of the diameter R0 of the cylindrical cavity 30a. Has been done. The introduction portion 21a is arranged near the inner side surface 30b of the resonator 30 at a predetermined angular position around the central axis O of the cavity 30a. That is, the minimum separation distance G between the introduction portion 21a and the inner side surface 30b is the inner side surface 30b of the distance between the inner side surface 30b and the introduction portion 21a that is closer to the inner side surface 30b. This indicates the minimum distance from the introduction portion 21a.

Next, device characteristics of the microwave device 100 of the present embodiment will be described with reference to FIG. FIG. 4 is a graph for explaining device characteristics of the microwave device 100, and is a graph showing a result of simulation when liquid toluene is used as a heating target. In FIG. 4, the horizontal axis represents the length L of the antenna, the left vertical axis represents the net incident power P1 [W] of the microwave into the cavity 30a, and the right vertical axis represents the maximum of the toluene heated by the microwave. Shows the temperature T [° C.] of. In addition, in FIG. 4, the simulation result of the portion surrounded by the broken line is the result of the example of the microwave device 100 of the present embodiment in which the distal end portion 21a1 of the introduction portion 21a is brought into contact with the lower wall portion 33. The simulation result of the portion surrounded by the dotted chain line is the result of the comparative example. In this comparative example, for example, a recess is formed in the lower wall portion 33 at a position corresponding to the tip portion 21a1 of the introducing portion 21a, and the tip portion 21a1 of the introducing portion 21a and the lower wall portion 33 (specifically, the bottom surface of the recess portion are formed). And a side surface), and the tip portion 21a1 is electrically insulated from the lower wall portion 33. That is, the length L of each antenna is the same in the example and the comparative example, but in the example, the leading end 21a1 of the introducing portion 21a is in contact with the lower wall portion 33, and in the comparative example, the introducing portion 21a. The leading end portion 21a1 does not contact the lower wall portion 33.

In the simulation in this embodiment, the following conditions were set as basic conditions.
The object to be heated is liquid toluene, and the incident power P0 of the microwave output from the microwave generator 10 is 10 [W]. The flow pipe 40 is made of borosilicate glass, the spiral winding diameter R1 of the spiral portion 41 of the flow pipe 40 is 12 [mm], the winding pitch P of the spiral portion 41 is 8 [mm], and the pipe diameter (inner diameter of the flow pipe 40 is ) R2 is 2.4 [mm]. The temperature of the liquid (toluene) at the inlet of the flow pipe 40 is room temperature (for example, 30 [° C.]), and the flow rate of the liquid (toluene) flowing through the flow pipe 40 is 1 [ml / min]. The diameter R1 of the cavity 30a (in other words, the inner diameter of the cylindrical body 31) is 91.2 [mm], the height H of the cavity 30a is 32 [mm], and the length L of the antenna is 32 [mm]. is there. The minimum separation distance G between the introduction portion 21a (antenna) and the inner side surface 30b of the resonator 30 is 4 [mm]. The oscillation frequency f is assumed to match the frequency at which the net incident power P1 and the temperature T show the highest values when the oscillation frequency f is swept in the ISM frequency band. That is, under the basic conditions, the oscillation frequency f matches the resonance frequency F of the resonator 30.

As a result of the simulation under the basic conditions, as shown by a portion surrounded by a broken line in FIG. 4, the net incident power P1 is only slightly decreased from the incident power P0 of 10 [W], It is about 7-8 [W]. Therefore, the reflected waves of the microwaves from the cavity 30a are relatively small, and they are almost matched. Further, the temperature T is about 70-80 [° C.], and the microwave device 100 of the present embodiment in which the introduction portion 21a is in contact with the lower wall portion 33 has low microwave power. It has good heating performance. Further, as compared with the result of the comparative example surrounded by the chain double-dashed line in FIG. 4 (when the introduction portion 21a is not in contact with the lower wall portion 33), the microwave device 100 of the present embodiment is similar to the comparative example and the antenna. Although the length L is the same, the introduction portion 21a comes into contact with the lower wall portion 33, so that the net incident power P1 and the temperature T sharply increase from the comparative example, which is extremely good as compared with the comparative example. It can be seen that it has various device characteristics. In the microwave device 100, the leading end portion (terminal end) 21a1 of the introduction portion 21a contacts the lower wall portion 33 and is electrically short-circuited. As a result, the current flows through the introduction portion 21a, the lower wall portion 33, the portion of the tubular body 31 (side wall portion of the resonator 30) close to the introduction portion 21a, and the upper wall portion 32. In other words, the current flow path is formed by the introduction portion 21a, the lower wall portion 33, the portion of the cylindrical body 31 close to the introduction portion 21a, and the upper wall portion 32. With these, microwave feeding equivalent to the loop antenna is performed. The structure is built.

According to the microwave device 100 of the first embodiment, the introduction portion 21a of the central conductor 21 of the power feeding path portion 20 that introduces the microwave into the cavity 30a includes the upper wall portion 32 and the lower portion of the resonator 30. One of the wall portions 33 (upper wall portion 32 in the figure) is penetrated to protrude into the cavity 30a, and in the vicinity of the inner side surface 30b of the resonator 30 in parallel with the central axis O of the cavity 30a, That is, it is linearly stretched. Therefore, the introduction part 21a for introducing the microwave into the cavity 30a is constructed with a simple structure without performing a special forming process, and the introduction part 21a having the same shape is constructed with good reproducibility. Further, since the introduction portion 21a only extends linearly, the hole 32a through which the introduction portion 21a penetrates the one wall portion is, for example, matched with the outer diameter of the insulator 22 of the power feeding path portion 20. The diameter may be small, and the position of the introduction portion 21a (a part of the central conductor 21) in the cavity 30a can be easily determined by simply fitting the end portion of the insulator 22 into the small diameter hole 32a. As a result, in the microwave device 100, the shape and shape of the introduction part 21a and the position and orientation of the introduction part 21a in the resonator 30 (specifically, the cavity 30a) that constitute a part corresponding to a conventional loop antenna are different for each device. It does not easily fluctuate, and the degree of coupling of the microwave with the resonator 30 does not easily fluctuate from device to device. Therefore, variations in performance between devices are unlikely to occur, and the microwave device 100 having a predetermined performance is supplied with a simple structure and good reproducibility. In this way, it is possible to provide the microwave device 100 capable of suppressing performance variations with a simple structure.

Also, an electromagnetic field of TM010 mode is excited in the cavity 30a. In this mode, since the electric field is uniformly distributed in the direction of the central axis O of the cavity 30a, the electric field is constant in the direction of the central axis O (stretching direction). Then, the through hole 32a of the introduction portion 21a is formed in one wall portion (for example, the upper wall portion 32) of the upper wall portion 32 and the lower wall portion 33 that closes both ends in the central axis direction of the cavity 30a. ing. Therefore, the microwave device 100 has a structure in which the electric field distribution and the like are not easily affected by the opening of the hole 32a. Since the hole 32a can be made smaller than the above-described large opening required when the conventional loop antenna is molded outside the resonator, the microwave leakage through the hole 32a is extremely small, and It can be easily suppressed or prevented. Specifically, as in the present embodiment, by matching the inner diameter of the hole 32a with the outer diameter of the insulator 22 and fitting the insulator 22 into the hole 32a, microwave leakage can be completely prevented.

Here, the liquid (solution) has different dielectric properties depending on the liquid type. Therefore, it is desirable that the microwave device 100 can essentially heat liquids of various liquid types as dielectrics having different dielectric properties.

FIG. 5 is a graph for explaining the change in the device characteristics of the microwave device 100 when the heating target is changed, and shows the result of simulation under the same conditions as the basic conditions except for the liquid type. There is. As the liquid type, ethanol, methanol, ethylene glycol, acetonitrile, dimethyl sulfoxide, and water were given as an example in addition to toluene, and simulations were performed for each liquid type. In FIG. 5, for simplification of description, symbols abbreviated Tolu, ethanol, methanol, ethylene glycol, acetonitrile, dimethylsulfoxide, and water are shown as Tol, ET, MT, EG, AN, DMSO, and WT, respectively. ing. In FIG. 5, the simulation results of the net incident power P1, the temperature T, and the resonance frequency F of the microwave in the cavity 30a for the liquid type corresponding to the symbol are shown in order from the left. In FIG. 5, the horizontal axis represents the relative permittivity ε ′ of each liquid, the left vertical axis represents the net incident power P1 [W] and the resonance frequency F [GHz], and the right vertical axis represents each microwave heated. The maximum temperature T [° C] of the liquid is shown.

As can be seen from FIG. 5, toluene and acetonitrile have higher net incident power P1 and temperature T than other liquid species. That is, with respect to toluene and acetonitrile, which have a relatively small dielectric loss tangent tan δ and a low dielectric loss, the microwaves are less reflected from the cavity 30a and the matching is good. On the other hand, ethylene glycol and water have lower net incident power P1 and temperature T than other liquid species. That is, with respect to ethylene glycol and water, which have a relatively large dielectric loss tangent tan δ and a high dielectric loss, microwaves are often reflected from the cavity 30a, and it is difficult to obtain good matching. The resonance frequency F changes slightly depending on the liquid type, but all liquids are within the ISM frequency band of 2.4 to 2.5 [GHz], and microwaves in the ISM frequency band are included. It turns out that it can be heated with. From these, in the microwave device 100 according to the present embodiment in which the introduction portion 21a is in contact with the lower wall portion 33, good heating is possible except for the case of ethylene glycol or water having a relatively large dielectric loss tangent tan δ. It has been found that it is possible to perform good heat treatment with a single device, from toluene with a low relative permittivity ε'to dimethylsulfoxide with a relatively high relative permittivity ε ', which has characteristics. It was Conventionally, it has been considered difficult to heat a non-polar solvent such as toluene, which has a low relative permittivity ε'and a small microwave absorption, by microwaves. However, the microwave device 100 of the present embodiment can be used in a single device in the ISM frequency band from such a non-polar solvent to a polar solvent having a high relative permittivity ε ′ and a relatively large microwave absorption. A heat treatment can be performed. The above simulation is performed assuming that the parameters of the liquid, that is, the dielectric, do not change with temperature. In practice, the parameters of most liquids change as the temperature rises. Generally, as the temperature rises, the relative permittivity ε ′ of the liquid decreases. For example, in the case of water, the relative permittivity ε ′ decreases in the direction in which the reflection of microwaves from the cavity 30a decreases as the temperature rises. ε'changes. Therefore, even with water, the actual net incident power P1 and the temperature T are larger than the simulation result shown in FIG. 5, and a practical heating characteristic can be obtained. Although not shown, a matching device (in other words, impedance matching) that reflects the reflected wave between the directional coupler 15 and the resonator 30 (introducing part 21a) and makes it enter the cavity 30a again. By providing a container, the net incident power P1 and the temperature T are further increased.

In the present embodiment, the distal end portion 21a1 of the introduction portion 21a is electrically connected to the lower wall portion 33 which is the other wall portion of the upper wall portion 32 and the lower wall portion 33. As a result, as can be seen from the simulation results and the like shown in FIGS. 4 and 5, liquids other than liquids having a relatively high dielectric loss tan δ such as ethylene glycol and water (for example, toluene, ethanol, It is possible to easily provide the microwave device 100 that exhibits good heating characteristics when a heating target is methanol, acetonitrile, dimethyl sulfoxide, or the like. Further, by bringing the tip end portion 21a1 of the introduction portion 21a into contact with the upper surface of the lower wall portion 33, the introduction portion 21a can be stably supported by two-point support with a simple structure. In addition, in this embodiment, although the said one wall part was demonstrated as what is the upper wall part 32, it is not restricted to this and the said one wall part may be the lower wall part 33. In this case, the end portion of the outer conductor 23 is electrically connected to the lower wall portion 33, the lower wall portion 33 is formed with a hole 32a for penetrating the introduction portion 21a, and the other wall portion serves as the upper wall portion 32. The tip portion 21a1 of the introduction portion 21a may be brought into contact with the lower surface of the upper wall portion 32. Since the introduction part 21a is a part of the central conductor 21 made of a copper wire, the introduction part 21a penetrates through the hole 32a formed in the lower wall part 33 and linearly stabilizes itself in the cavity 30a. be able to.

FIG. 6 is a graph for explaining changes in the device characteristics when the height H of the cavity 30a of the microwave device 100 is changed. Specifically, when the leading end 21a1 of the introduction portion 21a is in contact with the lower wall portion 33, when only the height H of the cavity 30a under the basic conditions is changed for the liquid toluene as the heating object. It is a simulation result. In FIG. 6, the horizontal axis represents the height H [mm] of the cavity 30a, the left vertical axis represents the net incident power P1 [W] and the resonance frequency F [GHz], and the right vertical axis is heated by microwaves. It also shows the maximum temperature T [° C] of toluene. Further, since it is premised that the tip portion 21a1 of the introduction portion 21a is in contact with the lower wall portion 33, the value of the height H of the cavity 30a indicated by the horizontal axis matches the length L of the antenna.

As can be seen from FIG. 6, when the height H of the cavity 30a is changed, the net incident power P1 and the temperature T are changed. Therefore, when the height H of the cavity 30a is changed, the microwave reflection characteristic in the cavity 30a also changes. Specifically, the net incident power P1 and the temperature T are, for example, from 24 [mm] as the height H of the cavity 30a increases under the influence of the increase or decrease of the height H of the cavity 30a. It increases almost in the same way up to 48 [mm], decreases almost in the same way from 48 [mm] to 64 [mm], and then starts to increase. As described above, the net incident power P1 and the temperature T tend to increase and decrease substantially periodically as the height H of the cavity 30a changes. In the resonator 30, a TM010 mode electromagnetic field showing a uniform electric field distribution in the direction of the central axis O of the cavity 30a (that is, no change in electromagnetic field distribution) is excited. The wave reflection characteristic (coupling degree) varies depending on the height H of the cavity 30a. Specifically, in the present embodiment, since the tip end portion 21a1 of the introduction portion 21a is in contact with the lower wall portion 33, the length L of the antenna changes according to the height H of the cavity 30a. Therefore, the path length of the microwave feeding structure equivalent to the loop antenna formed via the introduction portion 21a, the lower wall portion 33, the portion of the cylindrical body 31 close to the introduction portion 21a, and the upper wall portion 32 is It changes according to the change in the height H of the body 30a (that is, the length L of the antenna). Then, as the path length changes, the microwave coupling state in the cavity 30a changes, and as a result, the microwave reflection characteristic (coupling degree) in the cavity 30a is the height H (antenna of the cavity 30a). Of length L). Further, the resonance frequency F is slightly within the ISM frequency band, although it is slightly changed by changing the height H of the cavity 30a (the length L of the antenna).

Also, the lower the height H of the cavity 30a, the more compact the device. For example, when the height H of the cavity 30a is 32 [mm], the net incident power P1 is about 7-8 [W] and the temperature T is about 70-80 [° C], which makes the device compact. It is possible to obtain the heating characteristics suitable for practical use. In addition, although the simulation was performed when the incident power P0 of the microwave was 10 [W], for example, when the incident power P0 is 50 [W], the temperature T can be as high as 250 [° C.].

FIG. 7 is a graph for explaining changes in the device characteristics when the minimum separation distance G between the inner surface 30b of the resonator 30 and the introduction portion 21a (specifically, the antenna) is changed. Specifically, when the tip end portion 21a1 of the introduction portion 21a is in contact with the lower wall portion 33, for the liquid toluene as the heating target, the inner side surface 30b of the resonator 30 and the introduction portion 21a (the above-mentioned It is a simulation result when only the minimum separation distance G between antennas) is changed. In FIG. 7, the horizontal axis represents the minimum separation distance G [mm], the left vertical axis represents the net incident power P1 [W] and the resonance frequency F [GHz], and the right vertical axis represents the toluene heated by microwaves. The highest temperature T [° C] is shown.

As can be seen from FIG. 7, when the leading end portion 21a1 of the introduction portion 21a is in contact with the lower wall portion 33 and the heating target is liquid toluene, as the minimum separation distance G becomes shorter, the net incident power P1 and the temperature T are increased. Will increase. For example, when the minimum separation distance G becomes shorter than 4 [mm] as the basic condition, it can be seen that the net incident power P1 and the temperature T further increase and the heating characteristic is further improved. On the other hand, the resonance frequency F is slightly within the ISM frequency band although it changes slightly due to the change in the minimum separation distance G. Although not shown, the same simulation was performed for other liquid types (ethanol, methanol, ethylene glycol, acetonitrile, DMSO, and water). In the case of toluene shown in FIG. 7, ethylene glycol and water were removed. Similarly, it was found that as the minimum separation distance G becomes shorter, the net incident power P1 and the temperature T increase. For example, like toluene, in the case of acetonitrile having a relatively small dielectric loss tangent tan δ and a low dielectric loss, when the minimum separation distance G is 4 [mm], the net incident power P1 is 9.9 [W], The temperature T is 97 [° C.], and extremely good heating characteristics can be obtained. Therefore, in the case of a liquid other than the liquid species having a relatively large dielectric loss tangent tan δ such as ethylene glycol or water (for example, toluene, ethanol, methanol, acetonitrile, dimethyl sulfoxide), the present embodiment As described above, the minimum separation distance G between the introduction portion 21a (the antenna) and the inner side surface 30b of the resonator 30 is 5% or less of the diameter R0 of the cylindrical cavity 30a (for example, 4 [mm]). When set to about), the heating characteristics are further improved.

Although not shown, in the case of ethylene glycol or water having a relatively large dielectric loss tangent tan δ, it was found that as the minimum separation distance G becomes longer, the net incident power P1 and the temperature T increase. For example, in the case of ethylene glycol, if the minimum separation distance G is increased from 4 [mm] to 15 [mm], the temperature T rises to 73 [° C] when the minimum separation distance G is 15 [mm], The resonance frequency F becomes 2.532 [GHz], which is outside the ISM frequency band. In the case of water, if the minimum separation distance G is increased from 4 [mm] to 20 [mm], the temperature T rises to 98 [° C] at the minimum separation distance G of 20 [mm], but the resonance The frequency F becomes 2.533 [GHz], which is outside the ISM frequency band. However, in the case of ethylene glycol, for example, if the minimum separation distance G is 10 [mm], the resonance frequency F can be kept within the ISM frequency band, and in this case, the temperature T becomes 57 [° C], Practical heating characteristics can be obtained in the frequency band. In the case of water, for example, if the minimum separation distance G is set to 15 [mm], the resonance frequency F can be kept within the ISM frequency band, and in this case, the temperature T becomes 97.5 [° C]. Practical heating characteristics can be obtained in the ISM frequency band. As described above, in the case of a liquid type having a relatively large dielectric loss tangent tan δ, such as ethylene glycol or water, the net incident power P1 and the temperature T increase as the minimum separation distance G increases, unlike other liquid types. It was found to exhibit characteristics. Therefore, in the case of a liquid type having a relatively large dielectric loss tangent tan δ such as ethylene glycol or water, when giving priority to ensuring that the resonance frequency F falls within the ISM frequency band, the minimum separation distance G is the cavity 30a. The diameter R0 (= 91.2 [mm]) of 20% or less (for example, about 10 [mm] for ethylene glycol, about 15 [mm] for water) may be set.

Next, a microwave device 100 'according to a second embodiment of the present invention will be described with reference to FIG. FIG. 8 is a schematic configuration diagram of a microwave device 100 'according to the second embodiment of the present invention. The same elements as those of the microwave device 100 according to the first embodiment are designated by the same reference numerals, the description thereof will be omitted, and only different portions will be described.

In the microwave device 100 ′, the tip portion 21 a 1 of the introduction portion 21 a is electrically insulated from the lower wall portion 33 which is the other wall portion of the upper wall portion 32 and the lower wall portion 33. In the present embodiment, the distal end portion 21a1 of the introduction portion 21a is located a predetermined distance before the lower wall portion 33 as the other wall portion. That is, the front end portion 21a1 of the introduction portion 21a does not contact the lower wall portion 33 as the other wall portion of the upper wall portion 32 and the lower wall portion 33. Therefore, the height H of the cavity 30a is larger than the length L of the antenna of the introduction portion 21a. Other configurations are the same as those in the first embodiment.

FIG. 9 is a graph for explaining a change in device characteristics when the length L of the antenna is changed in the microwave device 100 '. More specifically, it is a simulation result when only the length L of the antenna under the above-mentioned basic conditions is changed for the liquid toluene as the heating object within a range in which the tip portion 21a1 of the introduction portion 21a does not contact the lower wall portion 33. In FIG. 9, the horizontal axis represents the length L of the antenna, the left vertical axis represents the net incident power P1 [W] of the microwave into the cavity 30a, and the right vertical axis represents the maximum of the toluene heated by the microwave. Shows the temperature T [° C.] of. Further, it is premised that the leading end portion 21a1 of the introduction portion 21a is not in contact with the lower wall portion 33. The length L of the antenna is the same as 32 [mm] which is the height H of the cavity 30a under the basic conditions (the rightmost plot in the figure) or shorter.

As can be seen from FIG. 9, if the height H of the cavity 30a is fixed to 32 mm without changing and the length L of the antenna is changed, the net incident power P1 and the temperature T change. The net incident power P1 and the temperature T increase in the same manner from 5 [mm] to 15 [mm] as the antenna length L increases, and from 15 [mm] to 30 [mm] almost the same. It decreases and slightly increases from 30 [mm] to around 32 [mm]. In this way, when the length L of the antenna is changed within a range in which the tip 21a1 of the introduction portion 21a does not contact the lower wall portion 33, the net length L (15 [mm] in the figure) of the antenna is changed. The incident power P1 and the temperature T show the maximum values. As described above, the microwave device 100 ′ has a device characteristic having a peak property with respect to the net incident power P 1 and the temperature T.

Further, the maximum values of the net incident power P1 and the temperature T in this embodiment are the net incident power P1 and the temperature in the example surrounded by the broken line in FIG. 4 (when the introduction portion 21a is in contact with the lower wall portion 33). Greater than the value of T. Here, for example, the linear shape of the introducing portion 21a is maintained sufficiently stable without contacting the tip portion 21a1 of the introducing portion 21a with the lower wall portion 33, and the introducing portion 21a is cantilevered by the upper wall portion 32. May be stable due to support. Therefore, in such a case, priority is given to the improvement of the net incident power P1 and the temperature T, and the tip portion 21a1 of the introduction portion 21a is not brought into contact with the lower wall portion 33 as in the present embodiment, and the antenna length is increased. It is advisable to set the length L to a length (15 [mm] in the figure) where the net incident power P1 and the temperature T show the maximum value.

FIG. 10 is a graph for explaining changes in device characteristics when the heating target is changed in the microwave device 100 ′, and is a graph similar to FIG. 9. More specifically, FIG. 9 shows a simulation result when the heating target is changed to methanol and only the length L of the antenna under the above basic condition is changed within a range in which the tip 21a1 of the introduction portion 21a does not contact the lower wall portion 33. It is the figure which overlapped with the simulation result in the case of the shown toluene (non-contact).

As can be seen from FIG. 10, even in the case of methanol, changing the antenna length L changes the net incident power P1 and the temperature T. The net incident power P1 and the temperature T are, for example, two peaks of the net incident power P1 and the temperature T in the case of methanol when the length L of the antenna is changed from 5 [mm] to around 32 [mm]. Has appeared in. As described above, the microwave device 100 ′ has a device characteristic having a peak property with respect to the net incident power P 1 and the temperature T even in the case of methanol.

In the case of methanol, the values of the net incident power P1 and the temperature T at the higher peak of the two peaks are not shown in the figure, but the values in the case where the introduction part 21a is in contact with the lower wall part 33 The values are substantially the same as the values of the net incident power P1 and the temperature T. As described above, even in the case of methanol, when the linear shape of the introduction portion 21a is maintained as described above and is stabilized by cantilever support, priority is given to improvement of the net incident power P1 and the temperature T, and As in the embodiment, the tip 21a1 of the introduction portion 21a is not brought into contact with the lower wall portion 33, and the length L of the antenna is the length at which the net incident power P1 and the temperature T show the peak of the higher side (in the figure, It is preferable to set it to about 28 [mm]. Further, as can be seen from FIG. 10, in the case of toluene, the net incident power P1 and the temperature T show maximum values when the antenna length L is approximately 15 [mm], and in the case of methanol, the antenna length is When L is approximately 27.5 [mm], the net incident power P1 and the temperature T show maximum values. That is, the length L of the antenna that can perform the efficient heating process changes according to the type of the heating target. In the second embodiment, the insulator is sandwiched between the distal end portion 21a1 of the introduction portion 21a and the lower wall portion 33 (that is, the other wall portion of the upper wall portion 32 and the lower wall portion 33). You may comprise. As a result, the introduction portion 21a can be stably and reliably supported by the two-point support.

Also in the microwave device 100 ′ according to the second embodiment, the shape of the introduction part 21 a and the position and orientation of the introduction part 21 a in the resonator 30 are unlikely to vary from device to device, and the degree of coupling of the microwave with the resonator 30 is also small. It is possible to provide a device that is less likely to vary from device to device and that can suppress performance variations with a simple structure.

Next, modified examples of the microwave device 100 and the microwave device 100 ′ in each of the above embodiments will be described with reference to FIGS. 11 to 18.

11 is a diagram for explaining a modification of the introduction unit 21a in the microwave device 100 and the microwave device 100 ', and is a cross-sectional view corresponding to FIG. In each of the above-described embodiments, only one introduction portion 21a is provided in the cavity 30a, but the number of introduction portions 21a is not limited to this, and may be plural. For example, as shown in FIG. 11, the introducing portions 21a may be provided in parallel at a plurality of locations (five locations in the figure). A plurality of introduction parts 21a are arranged at intervals in the radial direction of the cavity 30a, and the introduction part 21a to which the microwave is actually guided can be switched from among the plurality of introduction parts 21a. Thereby, the minimum separation distance G between the inner surface 30b of the resonator 30 and the introduction portion 21a (the antenna) can be appropriately switched according to the liquid type or the like to be heated. Although not shown, the microwave device 100 and the microwave device 100 'have only one introduction part 21a in the cavity 30a and can change the minimum separation distance G of this one introduction part 21a. A separate distance adjusting mechanism may be provided. The separation distance adjusting mechanism supports, for example, the introduction portion 21a on the one wall portion so that the position of the introduction portion 21a in the radial direction of the cavity 30a can be changed, and the inner surface 30b of the resonator 30 and the introduction portion can be changed. It is configured such that the minimum separation distance G between 21a can be changed.

FIG. 12 is a schematic configuration diagram for explaining an example in which a plurality of microwave output units 70 including the microwave generator 10 and the power feeding path portion 20 are provided in the microwave device 100 and the microwave device 100 ′. is there. FIG. 13 is a sectional view taken along the line CC of FIG. As shown in FIGS. 12 and 13, in the microwave device 100 and the microwave device 100 ′, a plurality of microwave output units 70 (four sets in the drawing) each including the microwave generator 10 and the power feeding path portion 20 are provided. May be In this case, the microwave output units 70 introduce microwaves into the cavity 30a through the introduction portions 21a of the respective power feeding path portions 20 with the same output and the same phase. For example, as shown in FIG. 13, the introduction portions 21a are arranged at equal angular pitches around the central axis O of the cavity 30a and in such a manner that the minimum separation distances G coincide with each other. This makes it possible to combine power. In this case, although not shown, if the above-mentioned matching device that reflects the reflected wave and makes it enter the cavity 30a again is further provided between the directional coupler 15 and the resonator 30 (introducing part 21a). Good. Thereby, for example, when the maximum output capacity of each microwave generator 10 is 10 w, the microwave device 100 and the microwave device 100 ′ have an output capacity of 40 w as a whole by the four sets of microwave output units, It is possible to achieve power combination that increases in proportion to the number of the microwave output units. 12 and 13, the arrangement and structure of the introduction portion 21a of each power feeding path portion 20 in the cavity 30a are shown symmetrically with respect to the central axis O, but they are strictly symmetrical. It does not have to be arrangement and structure.

FIG. 14 is a sectional view for explaining a modified example of the cavity 30a. In each of the above-described embodiments and modified examples, the cavity 30a is formed in a cylindrical shape, but the present invention is not limited to this. The cavity 30a may be formed in a regular square pole shape as shown in FIG. In this case, the TM110 mode electromagnetic field exhibiting a uniform electric field distribution in the direction of the central axis O of the cavity 30a is excited in the cavity 30a by the resonance of microwaves. Specifically, the regular square columnar cavity 30a may be formed inside the cylindrical body 31. For example, as shown in FIG. 14, the tubular body 31 may be formed in a rectangular tubular shape. Further, in the case of the regular square prism-shaped cavity 30a (that is, in the case of TM110 mode), the minimum separation distance G between the introduction portion 21a and the inner side surface 30b of the resonator 30 is equal to that of the cavity 30a facing each other. The value may be set to 5% or less or 20% or less of the distance L1 between the inner side surfaces. For details, in the case of liquids other than liquids with a relatively large dielectric loss tangent tanδ such as ethylene glycol and water (for example, toluene, ethanol, methanol, acetonitrile, dimethyl sulfoxide), the minimum separation is required. When the distance G is set to a value of 5% or less of the distance L1 between both inner side surfaces of the cavity 30a that face each other, the heating characteristics are further improved. Further, in the case of a liquid type having a relatively large dielectric loss tangent tan δ, such as ethylene glycol or water, when giving priority to ensuring that the resonance frequency F falls within the ISM frequency band, the minimum separation distance G is the cavity 30a. It is preferable to set the value to 20% or less of the distance L1 between the inner side surfaces facing each other.

FIG. 15 is a diagram for explaining a modified example of the power feeding path portion 20 (specifically, the connection portion of the outer conductor 23), and is a main-portion cross-sectional view corresponding to FIG. 2. In each of the above-described embodiments and modified examples, the end portion of the outer conductor 23 is in contact with the upper surface of the upper wall portion 32, and the end portion of the insulator 22 is larger than the end portion of the outer conductor 23 by the wall thickness of the upper wall portion 32. Although it is assumed to project downward, the invention is not limited to this. For example, as shown in FIG. 15, the end portions of the outer conductor 23 and the insulator 22 may extend to a position flush with the lower surface of the upper wall portion 32. In this case, the inner diameter of the hole 32a may be matched with the outer diameter of the outer conductor 23. Although not shown, the end portion of the outer conductor 23 and / or the end portion of the insulator 22 may be located inside the hole 32a, or slightly inside the cavity 30a from the lower surface of the upper wall portion 32. It may be protruding.

FIG. 16 is a diagram for explaining a modified example of the lower wall portion 33 of the resonator 30 in the microwave device 100 'of the second embodiment. In the microwave device 100 ′, it suffices that the leading end portion 21 a 1 of the introduction portion 21 a does not contact the lower wall portion 33. Therefore, as shown in FIG. 16, the length L of the antenna (in other words, the protruding length from the lower surface of the upper wall portion 32) is made longer than the height H of the cavity 30 a, and the lower wall portion 33 has the introduction portion 21 a. A concave portion 33a may be formed or provided in a portion corresponding to the tip portion 21a1. In this case, it suffices that the tip portion 21a1 of the introduction portion 21a extends into the recess 33a and is not in contact with the inner surface of the recess 33a. In this case, the length of the portion functioning as the antenna in the introduction part 21a for introducing the microwave (that is, the substantial length of the antenna) becomes the height H of the cavity 30a. Although not shown, an insulating piece may be provided between the tip end portion 21a1 of the introduction portion 21a and the upper surface of the lower wall portion 33. As a result, the introduction portion 21a can be reliably supported, and the insulation between the introduction portion 21a and the lower wall portion 33 can be reliably performed. Further, an insulating piece may be provided between the recess 33a and the introduction portion 21a shown in FIG. Although not shown, a concave portion into which the tip portion 21a1 of the introduction portion 21a can be fitted is formed in the lower wall portion 33 of the microwave device 100 of the first embodiment, and the tip portion of the introduction portion 21a is formed in this depression portion. 21a1 may be fitted. As a result, the introduction portion 21a can be supported and electrically connected to the lower wall portion 33 of the introduction portion 21a. In the second embodiment as well, the one wall portion is described as the upper wall portion 32, but the present invention is not limited to this, and the one wall portion may be the lower wall portion 33. In this case, the end portion of the outer conductor 23 is electrically connected to the lower wall portion 33, the lower wall portion 33 is formed with a hole 32a for penetrating the introduction portion 21a, and the other wall portion serves as the upper wall portion 32. It suffices that the distal end portion 21a1 of the introduction portion 21a is electrically insulated from the upper wall portion 32 and is positioned a predetermined distance before the upper wall portion 32. Further, when the recess 33a is provided, it may be provided on the upper wall portion 32.

17 and 18 are conceptual diagrams for explaining an example of a case where a length adjusting mechanism for changing the length of a portion functioning as an antenna in the introducing unit 21a is provided. As shown in FIG. 9 and FIG. 10, the value of the length L of the antenna showing efficient heating characteristics differs depending on the type of the heating target. Therefore, in the microwave device 100 ′ of the second embodiment, as shown in FIG. 17, the microwave device 100 ′ may be provided with an adjusting mechanism (a supporting portion 80 described later) capable of adjusting the length (projection length) L of the antenna, or As shown in FIG. 18, while the length L of the antenna is fixed, the length around the distal end portion 21a1 side of the introduction portion 21a is adjusted by an obstacle (a cylinder 90 described later). Alternatively, the substantial length of the antenna may be adjustable.

Specifically, as shown in FIG. 17, the microwave device 100 ′ is provided on the one wall portion (upper wall portion 32 in the figure) and can slide the power feeding path portion 20 in the direction of the central axis O. The support part 80 which supports in. The support portion 80 has an inner peripheral surface 80a with which the outer peripheral surface of the end portion side of the outer conductor 23 is in sliding contact, and the end portion of the outer conductor 23 and the one wall portion (upper wall portion 32 in the figure) of the outer conductor 23. It electrically connects the two. For example, by sliding the outer conductor 23 along the support portion 80 from the state shown in FIG. 17 (A) to the state shown in FIG. 17 (B), the outer conductor 23 projects into the cavity 30a of the introduction portion 21a. It is possible to adjust the length L itself of the part (that is, the antenna) in which it is present. The support portion 80 is made of, for example, an aluminum member, and is formed in a tubular shape having a flange portion at one end thereof. The support portion 80 is fixed to the one wall portion by fixing the flange portion to the one wall portion by a fastening member such as a bolt (not shown). Although not shown, a small screw is screwed into the cylindrical wall of the support portion 80 so as to penetrate the cylindrical wall, and the tip of the small screw presses the outer peripheral surface of the outer conductor 23. The outer conductor 23 is connected and fixed to the resonator 30 together with the center conductor 21 and the insulator 22. Thereby, the length L of the antenna of the introduction part 21a is determined. For example, the length L of the antenna in the introducing portion 21a in the state shown in FIG. 17B is shorter than the length L of the antenna in the introducing portion 21a in the state shown in FIG. 17A. The power supply path portion 20 does not need to be provided with the protective film 24 shown in FIG. In this case, the power feeding path portion 20 may use a so-called semi-rigid type coaxial cable that uses, for example, a cylindrical cylindrical body made of copper as the outer conductor 23.

Further, as shown in FIG. 18, the microwave device 100 ′ has a central axis O with respect to the other wall portion at a portion corresponding to the introduction portion 21 a in the other wall portion (the lower wall portion 33 in the figure). The cylindrical body 90 may be provided so as to be slidable in the direction. The tubular body 90 surrounds the portion of the introduction portion 21a on the side of the distal end portion 21a1. By sliding the tubular body 90 to an appropriate position in the direction of the central axis O, the length L'of the region of the outer peripheral surface of the introduction portion 21a that is directly exposed to the cavity 30a is adjusted. Here, a portion (LL ′) where the introduction portion 21a and the tubular body 90 overlap is a portion that receives a dielectric effect, and a substantial length that functions as an antenna in this portion (LL ′). Changes according to the value of the relative dielectric constant of the tubular body 90. Accordingly, the length of the portion functioning as the antenna in the introduction portion 21a can be substantially adjusted without changing the antenna length (that is, the protruding length) L, and the antenna length L itself shown in FIG. It is possible to obtain the same operational effect as in the case of directly adjusting. For example, by sliding the tubular body 90 along the hole 33b formed in the other wall from the state shown in FIG. 18A to the state shown in FIG. You can adjust the length of. The tubular body 90 is made of, for example, a ferroelectric material, and has an inner diameter that matches the outer diameter of the introduction portion 21a. Further, a cylindrical body supporting portion 95 for slidably supporting the cylindrical body 90 is attached to the other wall portion. The tubular body supporting portion 95 is made of, for example, an aluminum member, and is formed into a tubular shape having a flange portion at one end thereof. The tubular body support portion 95 is fixed to the other wall portion by fixing the flange portion to the other wall portion by a fastening member such as a bolt (not shown). Although not shown, a machine screw is screwed into the cylinder wall of the cylinder support portion 95 so as to penetrate the cylinder wall, and the tip of the machine screw presses the outer peripheral surface of the cylinder 90. As a result, the tubular body 90 is fixed to the resonator 30. Thereby, the substantial length of the antenna of the introduction part 21a is determined. For example, the substantial length of the antenna in the introduction portion 21a in the state shown in FIG. 18 (B) is longer than the substantial length of the antenna in the state shown in FIG. 18 (A). It should be noted that the one wall portion has, for example, a structure in which the outer conductor 23 is connected and fixed to the one wall portion as shown in FIG. Further, not limited to this, the structure shown in FIG. 17 may be adopted in the one wall portion. In this case, the length L of the antenna itself is adjusted by the structure shown in FIG. 17 and shown in FIG. The structure allows the length L of the antenna to be substantially adjusted. That is, in the portion (LL ′) where the introduction portion 21a and the tubular body 90 overlap, a dielectric shortening effect occurs, and the characteristic of the microwave that the substantial length of the antenna changes is used. ..

Although not shown in the drawings, the directional coupler 15 and the resonator 30 (introduction) in the power feeding path portion 20 are not limited to the modifications shown in FIGS. The matching unit described above may be provided between the unit 21a). With this matching device, the reflected wave of the microwave from the cavity 30a can be canceled in a circuit manner. As a result, the net incident power P1 is further increased, and depending on the performance of the matching device, most of the microwave power of the microwave output from the microwave generator 10 at the predetermined incident power P0 is raised to the heating target. It can be used for temperature, and the device characteristics (temperature rising characteristics) can be further improved.

Also, in each of the above-described embodiments and the modified examples thereof, the distribution pipe 40 has the spiral portion 41, but the distribution pipe 40 is not limited to this, and may be a straight pipe that extends straight. In addition, in the first embodiment, the insertion hole 32a of the introduction portion 21a is formed in the upper wall portion 32, and the distal end portion 21a1 of the introduction portion 21a is in contact with the lower wall portion 33, but the present invention is not limited to this. The hole 32a may be formed in the lower wall portion 33, and the leading end portion 21a1 of the introduction portion 21a may be in contact with the upper wall portion 32.

Further, in each of the above-described embodiments and the modified examples thereof, the power feeding path portion 20 is made of the coaxial cable, but the present invention is not limited to this, and the center conductor, the insulator covering the center conductor, and the insulator are covered. It suffices as long as it has an external conductor, extends coaxially, and guides the microwave output from the microwave generator 10 at a predetermined incident power P0 to the resonator 30. For example, the power feeding path unit 20 is a microwave output unit (for example, an output terminal unit of an output circuit) in a microwave generator including the microwave generator 10, the isolator 14, the directional coupler 15, the non-reflection terminator 16, and the like. It may be configured to include a connection connector that connects the resonator 30 and a resonator-side connector that is provided on the one wall portion and that connects to the connection connector. Specifically, the connector has a copper wire member forming a part of the central conductor, a part of the outer conductor, and a void as the insulator provided around the copper wire member. And a cylindrical body made of aluminum that extends in a line. By fitting or screwing this tubular body, which is a part of the outer conductor, into the resonator-side connector, the end portion of the outer conductor is electrically connected to the one wall portion. The resonator-side connector is electrically connected to a copper wire member forming a part of the central conductor of the connector, and is vacant while being electrically insulated from the one wall portion. It is configured to have an introduction portion 21a that protrudes into the body 30a and extends in the vicinity of the inner side surface 30b of the resonator 30 and parallel to the central axis O.

Further, in each of the above-described embodiments and the modifications thereof, the microwave device 100 and the microwave device 100 ′ have been described by way of example of the case where the microwave device 100 and the microwave device 100 ′ are a flow type in which heat treatment is performed while circulating a liquid, but the present invention is not limited to this. A batch type in which heat treatment is performed in a stationary state may be used. Further, the object to be heated is a liquid, but the object to be heated is not limited to this and may be a solid. The solid also includes aggregates of granular materials and powdery materials.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and the above modification, and various modifications and changes can be made based on the technical idea of the present invention.

10 ... Microwave generator 20 ... Power supply path section (coaxial cable)
21 ... Central conductor 21a ... Introductory part 21a1 ... Tip part 22 ... Insulator 23 ... Outer conductor 30 ... Resonator 30a ... Cavity 30b ... Inner surface 32. ..Upper wall (one wall)
32a ... Hole 33 ... Lower wall (other wall)
40 ... Distribution pipe 41 ... Spiral part 70 ... Microwave output unit 80 ... Support part 90 ... Cylindrical body 100 ... Microwave device 100 '... Microwave device O ...・ Center axis

Claims

A microwave generator that generates and outputs microwaves;
A center conductor, an insulator covering the center conductor, and an outer conductor covering the insulator, and coaxially extending, and a feeding path portion for guiding the microwave output from the microwave generator,
A cavity into which the microwave guided by the power feeding path is introduced is provided inside, and a uniform electric field distribution is shown in the cavity in the direction of the central axis of the cavity due to the resonance of the microwave. A resonator in which an electromagnetic field of TM010 mode or TM110 mode is excited,
In a microwave device for heating an object supplied into the cavity by the microwave,
The end portion of the outer conductor is electrically connected to one wall portion of the upper wall portion and the lower wall portion that closes both ends in the central axis direction of the cavity in the resonator,
The center conductor is an introduction part for introducing the microwave into the cavity, and penetrates a hole formed in the one wall part in a state of being electrically insulated from the one wall part. The microwave device having the introduction part that protrudes into the cavity and extends parallel to the central axis in the vicinity of the inner surface of the resonator.
The microwave device according to claim 1, wherein the leading end portion of the introduction portion is electrically connected to the other wall portion of the upper wall portion and the lower wall portion.
The cavity is formed in a cylindrical shape in the TM010 mode, and is formed in a regular square pillar shape in the TM110 mode.
The minimum separation distance between the introduction part and the inner side surface is set to a value of 20% or less of the diameter of the cavity in the TM010 mode, and is opposed to each other in the cavity in the TM110 mode. The microwave device according to claim 2, wherein the microwave device is set to a value of 20% or less of a distance between both inner side surfaces.
The microwave device according to claim 1, wherein a tip portion of the introduction portion is electrically insulated from the other wall portion of the upper wall portion and the lower wall portion.
The tip portion of the introduction portion is located a predetermined distance before the other wall portion,
An inner periphery, which is provided on the one wall portion and supports the power feeding path portion slidably in the direction of the central axis, and an outer peripheral surface of a portion of the outer conductor on the end portion side is slidably contacted The microwave device according to claim 4, further comprising: the support portion having a surface and electrically connecting the terminal end portion of the outer conductor and the one wall portion.
A cylinder body slidably supported in the direction of the central axis with respect to the other wall portion at a portion of the other wall portion corresponding to the introduction portion, the tip portion side of the introduction portion. The microwave device according to claim 4, further comprising: the cylindrical body surrounding the portion of the.
The microwave device according to claim 1, wherein the introduction unit is provided in parallel at a plurality of locations.
A plurality of microwave output units including the microwave generator and the power feeding path portion are provided,
The microwave device according to claim 1, wherein the microwave output units have the same phase as each other and introduce the microwave into the cavity through the introduction portion in each of the power feeding path portions.
The object is a liquid,
The microwave device according to claim 1, further comprising a flow pipe that is provided so as to penetrate the cavity of the resonator and that allows a liquid as the object to flow therethrough.
The microwave device according to claim 1, wherein the flow pipe has a spiral portion that spirally extends in the cavity with the central axis as a spiral central axis.