JP3625589B2 - Microwave heating device - Google Patents

Description

上式（１）において、「λ」はマイクロ波の自由空間波長であり、「Ａ」は加熱用導波管の幅広面の寸法である（図４参照）。上式（１）に従えば、例えばＡ＝９６ｍｍのときに管内波長λｇは約１５８ｍｍとなり、Ａ＝１０９．２ｍｍのときに管内波長λｇは約１４８ｍｍとなる。
【００２３】
【発明の効果】
以上説明したように本発明によれば、導波管形マイクロ波加熱炉における被加熱物の走行方向の長さをできるだけ短く保ちつつ、被加熱物が通過する直線部の本数を多くすることができる。このため、導波管形マイクロ波加熱炉における被加熱物の通過作業等を複雑にすることなく、マイクロ波エネルギーの吸収効率を向上させることができる。
【図面の簡単な説明】
【図１】本発明によるマイクロ波加熱装置を構成する導波管形マイクロ波加熱炉の内部構成を示す平面図である。
【図２】本発明によるマイクロ波加熱装置の全体構成を示す図である。
【図３】図２に示す導波管形マイクロ波加熱炉の側面図である。
【図４】断面が矩形状の導波管の基本寸法を示す図である。
【図５】従来の導波管形マイクロ波加熱炉の内部構成を示す平面図である。
【符号の説明】
１ マイクロ波発振器
５ テーパ導波管（連結用導波管）
６ 導波管形マイクロ波加熱炉
７ 加熱用導波管
７ａ 直線部
７ｂ Ｕターン部（折曲部）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a microwave heating apparatus, and more particularly to an improvement of a waveguide-type microwave heating furnace that irradiates an object to be heated with microwaves.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a microwave heating apparatus including a microwave oscillator and a waveguide-type microwave heating furnace is known in order to efficiently heat a relatively thin object such as paper or sheet. In this microwave heating apparatus, microwaves oscillated by a microwave oscillator are supplied to a waveguide type microwave heating furnace via a connecting waveguide.
[0003]
FIG. 5 is a plan view showing an internal configuration of a conventional waveguide type microwave heating furnace. As shown in FIG. 5, this conventional waveguide-type microwave heating furnace 26 has a rectangular cross section that can pass through microwaves in the same manner as the case 26a and the connecting waveguide 28 disposed in the case 26a. And a heating waveguide 27. The heating waveguide 27 includes a plurality of straight portions 27a and an arcuate U-turn portion (bent portion) 27b connecting the straight portions 27a. The straight portion 27a and the U-turn portion 27b are In the path from the coupling waveguide 28 to the end of the dummy load 12 at the terminal end, it is alternately and repeatedly formed. The rotation angle α of the U-turn portion 27b of the heating waveguide 27 is 180 °.
[0004]
In the waveguide type microwave heating furnace 26 shown in FIG. 5, for example, when a sheet-like object to be heated is dried, it is provided on the side of the straight portion 27 a of the case 26 a and the heating waveguide 27. The sheet-like object to be heated 13 is passed through the slot 15 (see FIG. 3), and the microwave energy is absorbed by the object to be heated 13 in the process of sequentially passing through the plurality of straight portions 27a of the heating waveguide 27. ing.
[0005]
[Problems to be solved by the invention]
However, as is apparent from FIG. 5, in the conventional microwave heating apparatus, if the number of straight portions 27a of the heating waveguide 27 increases, the object 13 to be heated in the waveguide type microwave heating furnace 26 is increased. There is a problem that the length L in the traveling direction is inevitably long, and it is very difficult to pass the article 13 to be heated.
[0006]
It is possible to divide the waveguide type microwave heating furnace 26 into two in order to make the article to be heated 13 pass easily. However, in such a method, leakage of microwaves increases, If measures against leakage are taken, there is a problem that the waveguide-type microwave heating furnace becomes expensive.
[0007]
The present invention has been made in consideration of the above points, and while the length of the object to be heated in the waveguide type microwave heating furnace is kept as short as possible, the heating guide through which the object to be heated passes is provided. An object of the present invention is to provide a microwave heating apparatus capable of increasing the number of straight portions of the wave tube.
[0008]
[Means for Solving the Problems]
The present invention includes a microwave oscillator and a microwave heating furnace having a heating waveguide connected to the microwave oscillator via a coupling waveguide, and the heating waveguide of the microwave heating furnace includes: The microwave heating apparatus includes a straight portion and a bent portion, and the bent angle of the bent portion exceeds 180 °.
[0009]
According to the present invention, since the bending angle of the bent portion exceeds 180 °, the adjacent straight portions can be brought close to each other, and thus the length in the direction perpendicular to the straight portion of the microwave heating furnace. Can be shortened.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0011]
1 to 4 are diagrams showing an embodiment of a microwave heating apparatus according to the present invention. First, the whole microwave heating apparatus will be described with reference to FIG. As shown in FIG. 2, the microwave heating apparatus according to the present invention includes a microwave oscillator 1 that generates microwaves, a waveguide-type microwave heating furnace 6 that heats printing paper 13 that is a sheet-like object to be heated, and the like. The microwave oscillator 1 and the waveguide type microwave heating furnace 6 are connected to each other through an isolator 2, a power monitor 3, a matching unit 4, and a tapered waveguide (coupling waveguide) 5. . Here, the isolator 2 is for protecting the microwave oscillator 1 by absorbing the reflected energy from the waveguide type microwave heating furnace 6, and the power monitor 3 is for monitoring the incident energy and the reflected energy. Is. The power monitor 3 is connected to an indicator 3a for displaying the monitored value. The matching unit 4 is for matching the microwave oscillator 1 with the waveguide type microwave heating furnace 6 to effectively use the microwave energy.
[0012]
The waveguide type microwave heating furnace 6 is housed in a heating furnace housing case 10, and a hot air generator 8 is connected to the heating furnace housing case 10 via a hot air duct 11. . The warm air generator 8 prevents the condensation of moisture evaporating from the printing paper 13 that is a heated object by preheating the waveguide type microwave heating furnace 6. Further, microwave application devices such as the microwave oscillator 1, the isolator 2, the power monitor 3, and the hot air generator 8 are accommodated in the device housing 9.
[0013]
Next, the internal configuration of the waveguide type microwave heating furnace 6 will be described with reference to FIG. As shown in FIG. 1, a waveguide type microwave heating furnace 6 includes a case 6a and a heating guide having a rectangular cross section that is disposed in the case 6a and has a rectangular cross section that allows microwaves to pass therethrough. A wave tube 7 is provided. Among them, the heating waveguide 7 includes a plurality of straight portions 7a and an arcuate U-turn portion (bent portion) 7b connecting the straight portions 7a. The straight portion 7a and the U-turn portion 7b are connected to each other. Are repeatedly formed alternately in the path from the tapered waveguide 5 to the end of the dummy load 12 at the end. In FIG. 1, five U-turn portions 7 b are formed in the path of the heating waveguide 7, whereby the passage direction of the printing paper 13 in the waveguide type microwave heating furnace 6. Six straight portions 7a are formed so as to block the screen.
[0014]
Further, as shown in FIG. 1, the rotation angle (folding angle) β of the U-turn portion 7b of the heating waveguide 7 is larger than 180 °. As shown in FIG. 3, the plurality of linear portions 7a are alternately inclined and arranged close to each other.
[0015]
FIG. 3 is a side view of the waveguide type microwave heating furnace 6 shown in FIG. As shown in FIG. 3, a slot 15 is provided on the side surface of the central portion of the straight portion 7 a of the case 6 a and the heating waveguide 7, and the printing paper 13, which is a sheet-like object to be heated, passes through the slot 15. It is supposed to be.
[0016]
Next, the operation of the present embodiment having such a configuration will be described.
[0017]
As shown in FIG. 2, first, a printing paper 13 that is a sheet-like object to be heated is set so as to pass through a slot 15 (see FIG. 3) provided in the waveguide type microwave heating furnace 6. The printing paper 13 is run at a predetermined speed in the tubular microwave heating furnace 6. Note that the printing paper 13 travels in a form substantially orthogonal to the plurality of straight portions 7a of the heating waveguide 7 shown in FIG. 1, and sequentially passes through each straight portion 7a. On the other hand, in this state, a power source is applied to the microwave oscillator 1 to generate a microwave, and this microwave is passed through an isolator 2, a power monitor 3, a matching unit 4, and a tapered waveguide 5. The heat is supplied to a heating waveguide 7 provided in the wave heating furnace 6. As a result, the running printing paper 13 absorbs microwave energy from the straight portion 7a of the heating waveguide 7 that has passed, and is dried by heat generation. Note that the remaining microwave energy that is not absorbed by the printing paper 13 is absorbed by the dummy load 12.
[0018]
In the present embodiment, the heating waveguide 7 has a plurality of straight portions 7a, and an arcuate U-turn portion 7b that connects the straight portions 7a and has an arcuate rotation angle β greater than 180 °. Therefore, the adjacent straight portions 7a can be brought close to each other. For this reason, the number L of the linear portions 7a through which the printing paper 13 passes is maintained while keeping the length L of the waveguide microwave heating furnace 6 in the running direction of the printing paper 13 (a direction substantially orthogonal to the linear portions 7a) as short as possible. Can be more. Thereby, compared with the conventional waveguide type microwave heating furnace, the absorption efficiency of the microwave energy per length which the printing paper 13 passes can be improved markedly.
[0019]
In FIG. 1, five U-turn portions 7 b are formed in the path of the heating waveguide 7, and thereby the straight portions 7 a are formed for three reciprocations (that is, six). The number of 7a is not limited to this, and may be several or several tens. The number of straight portions 7a is determined in consideration of the degree of absorption of microwave energy in the object to be heated, and is usually several to dozens. If the object to be dried is printing paper or the like as described above and further improvement in the microwave energy absorption efficiency is desired, the number of straight portions 7a should be increased as much as possible.
[0020]
【Example】
Next, a specific embodiment of the waveguide type microwave heating furnace 6 shown in FIG. 1 will be described. As for the U-turn portion 7b of the heating waveguide 7 constituting the waveguide type microwave heating furnace 6, as a result of several experiments, the rotation radius r is set to 0.25-0. It turned out that a good result is obtained when it is 5 times. It should be noted that there is no particular problem even if the rotation radius r of the U-turn portion 7b is 0.5 times or more the guide wavelength λg, but the length of the printing paper 13 in the traveling direction of the waveguide type microwave heating furnace 6 is not problematic. L is unfavorable because it becomes larger than necessary.
[0021]
If the heating waveguide 7 is a waveguide having a rectangular cross section as shown in FIG. 4, the in-tube wavelength λg is expressed by the following equation (1).
[0022]
[Expression 1]

In the above formula (1), “λ” is the free space wavelength of the microwave, and “A” is the dimension of the wide surface of the heating waveguide (see FIG. 4). According to the above equation (1), for example, when A = 96 mm, the guide wavelength λg is about 158 mm, and when A = 109.2 mm, the guide wavelength λg is about 148 mm.
[0023]
【The invention's effect】
As described above, according to the present invention, it is possible to increase the number of straight portions through which the object to be heated passes while keeping the length of the object to be heated in the waveguide type microwave heating furnace as short as possible. it can. For this reason, the absorption efficiency of microwave energy can be improved without complicating the operation of passing an object to be heated in the waveguide type microwave heating furnace.
[Brief description of the drawings]
FIG. 1 is a plan view showing an internal configuration of a waveguide type microwave heating furnace constituting a microwave heating apparatus according to the present invention.
FIG. 2 is a diagram showing an overall configuration of a microwave heating apparatus according to the present invention.
3 is a side view of the waveguide type microwave heating furnace shown in FIG. 2. FIG.
FIG. 4 is a diagram showing basic dimensions of a waveguide having a rectangular cross section.
FIG. 5 is a plan view showing an internal configuration of a conventional waveguide-type microwave heating furnace.
[Explanation of symbols]
1 Microwave Oscillator 5 Tapered Waveguide (Linking Waveguide)
6 Waveguide Type Microwave Heating Furnace 7 Heating Waveguide 7a Straight Line 7b U-Turn (Bent)

Claims (2)

A microwave oscillator,
A microwave heating furnace having a heating waveguide connected to a microwave oscillator via a coupling waveguide;
The heating waveguide of the microwave heating furnace consists of a straight part and a bent part,
A microwave heating device, wherein a bending angle of the bent portion exceeds 180 °. The microwave heating apparatus according to claim 1, wherein the bent portion of the heating waveguide is formed in an arc shape, and the radius of the bent portion is 0.25 to 0.5 times the wavelength in the tube.

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