JP2016167423A - Microwave heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a microwave heating device in which the temperature of the whole heated object is measured reliably, by measuring the temperatures at a plurality of positions of the heated object simultaneously from the outside of a heating furnace, while reducing leakage of microwaves from the heating furnace, and grasping the temperature distribution thereof.SOLUTION: A plurality of openings are formed, as observation windows, in the wall surface of a heating furnace, and an infrared camera is installed closely to the outside of the heating furnace. When measuring the temperature of a heated objected by means of the infrared camera through these openings, the opening diameter of the observation windows is set less than 1/2 of the wavelength λ of the irradiating microwaves, thus reducing leakage of microwaves from the opening. Also, the central axis of the openings is aligned with the visual axis of the infrared camera from the center of the field of view thereof to the center of the openings, so that the openings are directed to the direction of the infrared camera 13. Furthermore, a conductive transparent material is disposed to close the openings.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a microwave heating apparatus.

  2. Description of the Related Art Conventionally, in a microwave heating apparatus that irradiates and heats an object to be heated placed in a heating furnace, for example, an infrared camera or the like is used as a sensor for measuring the temperature of the object to be heated. In this type of microwave heating device, the infrared camera is installed at a position where the entire object to be heated can be directly viewed within the field of view so that the temperature distribution of the entire object to be heated and the temperature of a specific part can be accurately measured. The

  As the installation location, for example, there is an example in which a measurement window is provided on the wall surface of the heating furnace, and the infrared camera is fixed so as to be directly embedded in the measurement window with the inside of the heating furnace as a visual field. In addition, when fixed directly to the heating furnace, the effect of the temperature rise of the heating furnace may directly affect the infrared camera as the temperature sensor, so install the infrared camera and the heating furnace at a predetermined distance. In some cases, the entire object to be heated is directly viewed through the openings as a plurality of observation windows provided in the heating furnace.

  FIG. 9 shows a model of an example of a conventional microwave heating apparatus in which the infrared camera and the heating furnace are separately provided as described above. In the microwave heating apparatus illustrated in FIG. 9, the heating furnace 81 that performs microwave heating is configured by a conductor such as a metal plate, and the inside is hollow. A waveguide 82 is connected to one side surface (the left side in FIG. 9) of the heating furnace 81, and microwaves from a microwave generator (not shown) are radiated into the heating furnace via the waveguide 82. Then, the object to be heated 83 is irradiated.

  In addition, three observation windows 811, 812, and 813 having an opening diameter r are provided on the upper surface of the heating furnace 81. The opening diameter r is smaller than half the wavelength of the microwave radiated into the furnace in consideration of leakage of the microwave. Further above that, an infrared camera 84 is provided at a distance d from the outer wall of the heating furnace 81 so that these three observation windows are included in the field of view. The infrared camera 84 directly views the object to be heated 83 through the three observation windows 811 to 813 and measures the temperatures of a plurality of different locations of the object to be heated 83.

JP 2009-301764 A (page 12, FIG. 1)

  By the way, the heating furnace 81 is also a kind of waveguide that is constituted by a metal wall around the periphery and forms a part as a microwave transmission path. As described above, when the opening as an observation window is provided in the heating furnace. Depending on the diameter of the opening, the microwave leaks slightly. In order to reduce the level of the leaking microwave, it is necessary to make the wall diameter of the heating furnace 81 thick in addition to making the opening diameter of the opening less than ½ of the wavelength λ of the microwave. However, if the wall surface of the heating furnace is thickened, the object to be heated cannot be directly viewed from the observation window located in the oblique visual field of the infrared camera 84, or the range in which the object can be directly viewed may be extremely narrow. This will be described with reference to FIG.

  FIG. 10 is an explanatory view exemplifying a range of an object to be heated that can be measured by the infrared camera 84 through three observation windows 811 to 813. As illustrated in FIG. 10, the observation window 812 facing the infrared camera 84 can measure the temperature of the heated object 83, but the observation windows 811 and 813 at both ends can measure the metal of the heating furnace 81. The object to be heated 83 cannot be directly viewed due to the thickness of the wall. Therefore, even if a plurality of observation windows are provided, it is impossible to measure the temperature at a plurality of different locations of the heated object 83 at the same time, and the temperature distribution of the heated object 83 is not accurately measured.

  In addition, since a standing wave due to the emitted microwave is formed in the heating furnace, the electric field strength of the microwave in the furnace is not uniform. For this reason, when an observation window is provided in a portion where the electric field strength is high, there is a problem that the amount of leakage increases even in an observation window having the same aperture diameter.

  Furthermore, the observation window may be sealed with glass or the like to keep the inside of the heating furnace visible from the outside of the heating furnace or to keep the gas inside the heating furnace. However, since glass is a dielectric for microwaves, it is necessary to make the aperture diameter of the observation window smaller than when the glass is not attached, so that the observability deteriorates, and the heated object 83 is particularly small. In some cases, accurate temperature measurement was difficult.

  The present embodiment has been made in consideration of the above-described circumstances, and while simultaneously reducing the leakage of microwaves from the heating furnace, the temperature at a plurality of locations of the object to be heated is measured from the outside of the heating furnace. An object of the present invention is to provide a microwave heating apparatus that grasps the temperature distribution and reliably measures the temperature of the entire object to be heated.

  In order to achieve the above object, a first microwave heating apparatus of the present embodiment accommodates a microwave generation unit that generates a microwave and an object to be heated, and introduces the microwave to the object to be heated. And a metal heating furnace in which an opening as an observation window for measuring the temperature of the object to be heated from the outside is formed on the wall surface, and spaced apart from the heating furnace, the observation of the heating furnace An infrared camera that measures the temperature of the object to be heated through a window, and the opening of the heating furnace has an opening diameter that is less than half of the wavelength of the microwave and a central axis that is the center of the infrared camera. A plurality of lines are formed so as to coincide with the visual axis from the center point of the visual field to the center of the opening.

  Further, the second microwave heating apparatus of the present embodiment accommodates a microwave generation unit that generates microwaves and an object to be heated, introduces the microwave, and irradiates the object to be heated. A metal heating furnace having an opening formed on the wall surface as an observation window for measuring the temperature of the object to be heated from the outside, and the object to be heated through the observation window of the heating furnace. And an infrared camera for measuring the temperature of the heating furnace, and the opening of the heating furnace has an opening shape that allows the entire object to be heated or a desired range to be viewed directly from the outside, and covers the entire opening. A conductive transparent material is disposed.

The block diagram which shows the structure of the 1st Example of the microwave heating apparatus which concerns on this embodiment. Explanatory drawing which shows an example of the positional relationship of the cross section of opening and an infrared camera. Explanatory drawing of the heating furnace in the 2nd Example of the microwave heating apparatus which concerns on this embodiment. Sectional drawing of the AB surface in Fig.3 (a). The block diagram which shows the structure of the 3rd Example of the microwave heating apparatus which concerns on this embodiment. Sectional drawing of the heating furnace 12b in the periphery of the opening 128. FIG. Sectional drawing of the opening periphery formed in the heating furnace 12b in the 4th Example of the microwave heating device which concerns on this embodiment. Sectional drawing for demonstrating the modification of the 4th Example illustrated in FIG. The block diagram which models and shows an example of the conventional microwave heating apparatus. Explanatory drawing which illustrated the range of the to-be-heated object which can measure temperature through an observation window.

  Below, the best form for implementing the microwave heating device which concerns on this embodiment is demonstrated with reference to FIGS.

  FIG. 1 is a block diagram showing the configuration of a first example of the microwave heating apparatus according to this embodiment. The microwave heating apparatus 1 includes a microwave generation unit 11, a heating furnace 12, an infrared camera 13, and a control unit 14. Then, the microwave generated by the microwave generator 11 is irradiated and heated on the object to be heated 16 accommodated in the heating furnace 12 and heated by the infrared camera 13 installed outside the heating furnace 12. The controller 14 is configured to control the heating of the article 16 to be heated by measuring the temperature of the object and controlling the level of the microwave generated by the microwave generator 11 based on the measurement result. Yes.

  The microwave generation unit 11 generates a microwave signal for irradiating the object to be heated 16 and sends it to the heating furnace 12. In the present embodiment, the microwave output level can be changed by control from the control unit 14 described later.

  The heating furnace 12 is made of metal, accommodates an object to be heated 16 therein, and heats the object to be heated 16 by irradiation with microwaves from the microwave generation unit 11. In this embodiment, the shape is a rectangular parallelepiped. An inlet 124 for introducing a microwave from the microwave generator 11 into the furnace is formed on one surface of the wall of the heating furnace 12. The inlet 124 is connected to the microwave generator 11 by the waveguide 15. Has been. Microwaves from the microwave generation unit 11 are radiated into the furnace from the introduction port 124 via the waveguide 15.

  When the heating furnace 12 having a rectangular parallelepiped shape is regarded as a waveguide, the temperature of the object 16 to be heated from the outside of the heating furnace 12 is applied to the wall surface (upper wall surface in FIG. 1) corresponding to the long side of the width. Three openings 121, 122, and 123 are formed in a row as observation windows for measuring. All of these three openings have an opening diameter r less than ½ of the wavelength λ of the microwave irradiated in the heating furnace 12, and the central axis of the opening is the center of the field of view of the infrared camera 13. It is formed so as to coincide with the visual axis from the point to the center of the opening. The formation of these openings will be described in detail with reference to FIG.

  FIG. 2 is an explanatory diagram showing an example of the positional relationship between the cross section of the wall surface of the heating furnace in which the openings 121, 122, and 123 as observation windows are formed and the infrared camera 13. In FIG. 2, the infrared camera 13 is installed at a distance d from the wall surface of the heating furnace 12, and among the three openings 121, 122, and 123, the opening 122 is the field of view of the infrared camera 13. It is assumed that the other openings 121 and 123 are formed in an oblique direction. The opening diameters r of the three openings 121, 122, and 123 are all less than ½ of the microwave wavelength λ. The central axes 121p, 122p, and 123p (shown by alternate long and short dash lines) of the respective apertures are a visual axis a, a visual axis b, and a visual axis from the central point of the field of view of the infrared camera 13 to the central point of each opening. And the visual axis c (illustrated by a broken line).

  Accordingly, the side wall of each opening is parallel to the thickness direction of the wall surface of the heating furnace 12 in the opening 122 at a position facing the field of view of the infrared camera 13, but the direction of the infrared camera 13 is in the openings 121 and 123. It is formed with an inclination with respect to the thickness direction. In this way, by forming the central axis of the opening in the direction of the infrared camera 13, when the object to be heated 16 is observed through the opening formed obliquely from the infrared camera 13, the object is heated by the side wall of the opening. Since the field of view to the object 16 is not obstructed, it is possible to simultaneously measure the temperature at a plurality of locations of the object to be heated 16 to grasp the temperature distribution, and to perform reliable temperature measurement of the entire object to be heated. It becomes possible.

  The infrared camera 13 is installed at a distance d from the wall surface of the heating furnace 12 and is heated from the outside of the heating furnace 12 through a plurality of openings 121, 122, and 123 as observation windows provided in the heating furnace 12. The temperature of the object 16 is measured. In the present embodiment, the distance d from the heating furnace 12 is, for example, a distance longer than ½ of the wavelength λ of the microwave, and the openings 121 to 123 provided in the heating furnace 12 are all the same. It is installed to be included in the field of view.

  In the example of FIG. 2, the opening 122 faces the center of the field of view, and the openings 121 and 123 are located in an oblique direction within the field of view. And since any opening is formed facing the direction of the infrared camera 13, the infrared camera 13 performs temperature measurement while simultaneously directly viewing a plurality of different locations of the object 16 to be heated in the heating furnace 12. Can do. The measurement result is displayed on, for example, a monitor unit (not shown) of the infrared camera 13 and sent to the control unit 14.

  The control unit 14 receives the temperature measurement result from the infrared camera 13 and controls the level of the microwave generated by the microwave generation unit 11 according to the heating state in the heating furnace 12 such as the temperature distribution of the article 16 to be heated. Monitor and control the heating status.

  As described above, in the microwave heating apparatus 1 of the present embodiment, when the object to be heated contained in the heating furnace is irradiated with microwaves and the temperature is measured, the observation window is used as an observation window on the wall of the heating furnace. In addition to forming a plurality of openings, an infrared camera is installed close to the outside of the heating furnace, and the temperature of the object to be heated is measured by the infrared camera through these openings. And about the some opening part provided in the wall surface of the heating furnace as an observation window, the leakage diameter of the microwave from an opening is each made by making the opening diameter into less than 1/2 of the wavelength (lambda) of the microwave to irradiate. Reduced.

  Further, the center axis of the opening is made coincident with the visual axis from the center of the field of view of the infrared camera to the center of the opening, and each opening is inclined with respect to the thickness direction of the heating furnace wall surface, so that the direction of the infrared camera 13 is It is formed to face. Thereby, since the to-be-heated object inside a heating furnace can be directly seen from each opening formed in the diagonal direction from the infrared camera 13, the temperature of several places of a to-be-heated object can be measured simultaneously.

  Therefore, when measuring the temperature of the object to be heated arranged from the outside to the inside of the heating furnace, it is possible to simultaneously measure the temperature at a plurality of locations of the object to be heated while reducing leakage of microwaves from the heating furnace. A microwave heating apparatus capable of grasping the temperature distribution and performing reliable temperature measurement of the entire object to be heated can be obtained.

  FIG. 3 is an explanatory diagram of a heating furnace in a second example of the microwave heating apparatus according to the present embodiment, and FIG. 3A is a model of an opening as an observation window provided on the upper wall surface of the heating furnace. FIG. 3B is a diagram showing an example of the electric field strength inside the heating furnace. In the second embodiment, the same parts as those in the first embodiment shown in FIGS. 1 to 2 are denoted by the same reference numerals, and description thereof is omitted.

  The second embodiment is different from the first embodiment in that a plurality of openings as observation windows are formed in the heating furnace. In the first embodiment, the same opening diameter is formed on the upper wall surface of the heating furnace 12. Whereas a plurality of r openings (three in the case of FIG. 1) are formed, in the second embodiment, as shown in FIG. A plurality of openings having different opening diameters are two-dimensionally formed on the upper wall surface of the heating furnace in accordance with the electric field intensity of the microwave. Hereinafter, the differences will be mainly described with reference to FIGS. 1 to 2 and FIGS.

  Similarly to the first embodiment illustrated in FIG. 1, the microwave heating apparatus according to the second embodiment also applies the microwave generated by the microwave generator 11 via the waveguide 15 to the heating furnace 12a. It is introduced into the interior and irradiated to heat the object to be heated 16 accommodated therein, and the temperature of the object to be heated is measured by the infrared camera 13 installed outside the heating furnace 12a. Based on the measurement result The controller 14 is configured to control the level of the microwave generated by the microwave generator 11 to control the heating of the article 16 to be heated.

  Here, in the second embodiment, a plurality of openings having different opening diameters are two-dimensionally arranged on the upper wall surface of the heating furnace 12a. An example is shown in FIGS. Fig.3 (a) is an example of the top view which modeled and showed the upper wall surface of the heating furnace 12a. FIG. 4 is an example of a cross section taken along the line AB in FIG. In the example of FIGS. 3A and 4, as openings having three different opening diameters, there are a plurality of openings 125 each having an opening diameter r5, an opening 126 having r6, and an opening 127 having r7. It is supposed to be arranged in a dimension. Each opening diameter is less than 1/2 of the wavelength λ of the microwave, and is based on the electric field strength of the microwave in the heating furnace 12a at each opening forming position illustrated in FIG. Thus, the opening diameter is large at a position where the electric field strength is low, and the opening diameter is small at a position where the electric field strength is high. That is, in this case, r5 <r6 <r7 <λ / 2. Thereby, the leakage of the microwave from each opening can be further reduced.

  In addition, as illustrated in the cross-sectional view of FIG. 4, each opening is formed to face the infrared camera 13 as in the first embodiment. That is, in FIG. 4, the opening 126 with the opening diameter r6 is in a position facing the infrared camera 13, and the opening 125 with the opening diameter r5 and the opening 127 with the opening diameter r6 are positioned in the oblique viewing direction from the infrared camera 13. It is supposed to be. The central axis of each opening is formed so as to coincide with the visual axis from the infrared camera 13 to the center of each opening. As a result, the opening formed in the oblique direction from the infrared camera 13 does not obstruct the field of view of the object to be heated 16 by the side wall, and the temperature at a plurality of locations of the object to be heated 16 is measured simultaneously. The distribution can be grasped and the temperature of the entire object to be heated can be reliably measured.

  As described above, in this embodiment, it is possible to obtain a microwave heating apparatus that can perform reliable temperature measurement of the entire object to be heated while further reducing leakage of microwaves from the heating furnace.

  FIG. 5 is a block diagram showing a configuration of a third example of the microwave heating apparatus according to the present embodiment. In the third embodiment, the same parts as those in the first embodiment shown in FIGS. 1 to 2 are denoted by the same reference numerals, and the description thereof is omitted. The third embodiment is different from the first embodiment in that an opening as an observation window is formed in the heating furnace. In the first embodiment, the opening diameter is microwaves on the upper wall surface of the heating furnace 12. In the third embodiment, the whole or a desired range of the object to be heated accommodated in the heating furnace is directly viewed from the outside. In addition, an opening having a large area can be formed, and a conductive transparent material is disposed so as to cover the entire opening. Hereinafter, the difference will be mainly described with reference to FIGS. 1 to 2 and FIGS.

  Similarly to the first embodiment illustrated in FIG. 1, the microwave heating apparatus 3 of the third embodiment also heats the microwave generated by the microwave generator 11 via the waveguide 15. Introduced in the furnace 12b, irradiated and heated the object to be heated 16 accommodated therein, and measured the temperature of the object to be heated with the infrared camera 13 installed outside the heating furnace 12b, the measurement result Based on the above, the control unit 14 is configured to control the heating of the article 16 to be heated by controlling the level of the microwave generated by the microwave generating unit 11.

  Here, in the microwave heating apparatus 3 according to the third embodiment, an opening 128 having a shape in which the entire inside of the object to be heated 16 can be directly viewed from the outside is formed on the upper wall surface of the heating furnace 12b. In 128, a transparent flat plate 1281 using a conductive transparent material is disposed. A cross-sectional view around the opening 128 is shown in FIG. FIG. 6 is an example of a cross-sectional view of the heating furnace 12 b around the opening 128.

  In the example shown in FIG. 6, a wide opening 128 is provided on the upper wall surface of the heating furnace 12b so that the object to be heated 16 can be seen directly from the outside of the furnace, and the opening 128 is closed. A transparent flat plate 1281 using a conductive transparent material is inserted and arranged, and is configured as a transparent window. In this embodiment, the transparent flat plate 1281 is formed of a conductive transparent material containing tin-doped indium oxide. And the infrared camera 13 measures the temperature of the to-be-heated object 16 from the outer side of the heating furnace 12b through the opening 128 which can directly view the to-be-heated object 16 and the transparent window which consists of the transparent flat plate 1281.

  Thus, the shape of the opening 128 formed on the wall surface of the heating furnace 12b is, for example, a shape having a wide opening area in accordance with the temperature measurement target range of the article 16 to be heated, and a transparent flat plate 1281 is formed in the opening 128. The infrared camera 13 can directly view the entire target range of the object 16 to be heated, and can reliably measure the temperature distribution. Further, since the transparent flat plate 1281 disposed in the opening 128 is conductive, the microwave in the heating furnace 12b is shielded by the transparent flat plate 1281, and leakage to the outside is prevented.

  Therefore, also in this embodiment, when measuring the temperature of the object to be heated arranged from the outside to the inside of the heating furnace, the temperature distribution of the entire object to be heated is reduced while reducing the leakage of microwaves from the heating furnace. A microwave heating apparatus capable of grasping and performing reliable temperature measurement can be obtained. In particular, when the inside of the heating furnace is kept at a high temperature or is filled with a fluid such as a gas, the heat from the opening can be obtained by sealing the heating furnace by placing a conductive transparent flat plate in the opening. Or a gas leak etc. can also be prevented.

  In this embodiment, the transparent plate 1281 made of a conductive transparent material is embedded in the opening 128. However, the conductive transparent material is formed in a film shape so as to cover the entire surface of the opening 128. You can also.

  FIG. 7 is a sectional view around the opening formed in the heating furnace 12b in the fourth example of the microwave heating apparatus according to the present embodiment. In the fourth embodiment, the same parts as those in the third embodiment shown in FIGS. 5 to 6 are denoted by the same reference numerals, and the description thereof is omitted. The fourth embodiment differs from the third embodiment in that, in the third embodiment, a flat plate using a conductive transparent material is disposed in the opening formed as an observation window in the heating furnace. In the fourth embodiment, this is not a flat plate but a lens shape. Hereinafter, only the difference will be described with reference to FIGS. 5 to 6 and FIG.

  As illustrated in FIG. 7, also in the present embodiment, as in the third embodiment illustrated in FIG. 5, the upper wall surface of the heating furnace 12 b has an opening through which the object to be heated 16 can be directly viewed from the outside. 128 is formed. In this opening 128, for example, a lens-shaped transparent plate 1282 using a conductive transparent material containing tin-doped indium oxide or the like is fitted and arranged. In this embodiment, the transparent plate 1282 is processed into a convex lens shape. The infrared camera 13 directly views the object 16 to be heated from the outside of the heating furnace 12b through the opening 128 in which the lens-shaped transparent plate 1282 is fitted, and measures the temperature.

  In this way, by arranging the lens-shaped transparent plate 1282 in the opening 128 formed in the heating furnace 12b, in addition to the same effect as in the third embodiment, in particular, even when the object to be heated is small, the infrared camera side Therefore, it is not necessary to increase the magnification and the sensitivity of the infrared camera can be sufficiently maintained, so that reliable temperature measurement can be realized even for a small object to be heated.

Modified example

  FIG. 8 is a modification of the above-described fourth embodiment. In this case, the transparent plate 1282 is processed into a concave lens shape, so that the entire object to be heated can be directly viewed without changing the size of the opening 128 even when the object to be heated 16 is relatively large. Therefore, reliable temperature measurement can be performed even on an object to be heated that is larger than the opening 128.

  Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1, 3 Microwave heating device 11 Microwave generation unit 12, 12a, 12b Heating furnace 13 Infrared camera 14 Control unit 15 Waveguide 16 Object to be heated 121, 122, 123, 125, 126, 127, 128 Opening 124 Inlet 1281 Transparent flat plate 1282 Lens-shaped transparent plate

Claims (5)

A microwave generator for generating microwaves;
Metal heating that contains an object to be heated, introduces the microwave, irradiates the object to be heated, and forms an opening on the wall surface as an observation window for measuring the temperature of the object to be heated from the outside A furnace,
An infrared camera that is installed apart from the heating furnace and measures the temperature of the object to be heated through an observation window of the heating furnace;
The opening of the heating furnace has an opening diameter of less than ½ of the wavelength of the microwave, and its central axis is made to coincide with the visual axis from the center point of the visual field of the infrared camera to the center of the opening. A microwave heating apparatus, wherein a plurality of microwave heating apparatuses are formed.   2. The microwave heating apparatus according to claim 1, wherein each of the plurality of openings is formed by changing the diameter of the opening based on the electric field strength of the microwave in the heating furnace at the opening forming position. . A microwave generator for generating microwaves;
Metal heating that contains an object to be heated, introduces the microwave, irradiates the object to be heated, and forms an opening on the wall surface as an observation window for measuring the temperature of the object to be heated from the outside A furnace,
An infrared camera that is installed apart from the heating furnace and measures the temperature of the object to be heated through an observation window of the heating furnace;
The opening of the heating furnace has an opening shape in which the entire object to be heated or a desired range can be directly viewed from the outside, and a conductive transparent material is disposed so as to cover the entire surface of the opening. A microwave heating device.   The microwave heating device according to claim 3, wherein the thickness of the conductive transparent material is formed in a lens shape.   5. The microwave heating apparatus according to claim 3, wherein the conductive transparent material is a glass with a transparent conductive film containing tin-doped indium oxide or FTO (Fluorine-doped tin oxide).