Monitoring device

Abstract

To improve narrowing of a visual field of a monitoring device due to the adhesion of dust.SOLUTION: A monitoring device (100) according to one embodiment of an invention comprises: a lens (4); a cover (5) for covering the peripheral face of the lens (4); and a plasma actuator (7) which includes a first electrode (71) for generating at least one of plasma (P) and an induced jet flow (F) generated by dielectric barrier discharge, toward the center axis (C) of the cover (5), and removes dust (D) with at least one of the plasma (P) and the induced jet flow (F).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a monitoring device, and more particularly to a monitoring device for monitoring the inside of a furnace.

Background Art

[0002] Conventionally, a monitoring device for monitoring the state inside a furnace is arranged in a combustion furnace such as a waste incineration facility. In this type of monitoring device, dust (dirt) adheres to a lens or the like due to combustion, and thus techniques for preventing or removing the adhesion of dust have been proposed.

[0003] For example, Patent Document 1 discloses a technique of discharging dust-proof gas toward the tip side of a lens tube. Further, Patent Document 2 discloses a technique of attaching a rotatable transparent body with blades (propeller mechanism) to the tip side of a lens tube.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, with the technique of Patent Document 1, it is not possible to sufficiently prevent the adhesion of dust, and it is necessary to periodically remove the dust manually (blowing operation). Furthermore, there is dust that cannot be removed even manually (dust that has entered the inner peripheral portion of the opening, etc.), and the field of view of the captured image may be partially missing.

[0006] Also, with the technique of Patent Document 2, maintenance of the mechanism part is required due to the addition of the propeller mechanism, and further, it is difficult to apply because the propeller mechanism is reflected in the camera.

[0007] One aspect of the present invention aims to provide a monitoring device that can improve the deterioration of the field of view due to dust adhesion without frequent maintenance.

Means for Solving the Problems

[0008] In order to solve the above problems, a monitoring device according to one aspect of the present invention is a monitoring device for monitoring the inside of a furnace, and includes a light guide unit that guides light from the inside of the furnace to a camera, a cylindrical cover that covers the peripheral surface of the light guide unit and has an opening at the tip on the furnace side for passing the light, and a first electrode that generates at least one of plasma generated by dielectric barrier discharge and a jet induced by the plasma toward the central axis of the cover, and a plasma actuator that removes dust adhering to the surface facing the inside of the furnace of the monitoring device or the inside of the monitoring device by at least one of the plasma and the jet.

Effects of the Invention

[0009] According to one aspect of the present invention, it is possible to provide a monitoring device that can improve the deterioration of the field of view due to dust adhesion without frequent maintenance.

Brief Description of the Drawings

[0010]

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Embodiments for Carrying Out the Invention

[0011] 〔Embodiment 1〕 Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 6. However, the following description is an example of a monitoring device according to the present invention, and the technical scope of the present invention is not limited to the illustrated examples.

[0012] (Overview of the Monitoring Device) First, with reference to FIG. 1, an overview of the monitoring device 100 according to the present embodiment will be described. FIG. 1 is a cross-sectional view showing a state where the monitoring device 100 according to the present embodiment is attached to the furnace 1. In the following description, the side facing the inside 11 of the furnace 1 (the left side in FIG. 1) may be referred to as the tip end side, and the side opposite to the tip end side (the right side in FIG. 1) may be referred to as the base end side.

[0013] The furnace 1 shown in FIG. 1 is, for example, a combustion furnace or a melting furnace, etc., and the inside 11 of the furnace is exposed to a high-temperature atmosphere. The monitoring device 100 is attached to a furnace wall 12 such as a side wall or an upper wall of the furnace 1 in order to monitor the state of the inside 11 of the furnace. In the illustrated example, a cylindrical fixture 2 is provided in a mounting hole 13 formed in the thickness direction of the furnace wall 12, and the tip end side of the monitoring device 100 is inserted into the mounting hole 13 via the fixture 2.

[0014] The fixture 2 is formed with a first vent hole 21 for introducing first sealing air A1 for dust prevention into the inside of the fixture 2. The first sealing air A1 introduced from the first vent hole 21 flows from the base end side to the tip end side through the gap between the outer peripheral surface of the cover 5 of the monitoring device 100 and the inner peripheral surface of the fixture 2, and is discharged from the tip end side of the fixture 2. By introducing the first sealing air A1 into the inside of the fixture 2, it is possible to prevent dust generated in the furnace 1 from adhering to the surface of the monitoring device 100 facing the inside 11 of the furnace, and to cool the cover 5 to prevent the temperature of the lens (light guiding part) 4 from rising excessively.

[0015] The monitoring device 100 includes a camera 3, a lens 4 that guides light from the furnace interior 11 to the camera 3, a cylindrical cover 5 that covers the outer peripheral surface (circumferential surface) of the lens 4, and an attachment 6 on which a plasma actuator described later is mounted. The camera 3 is connected to the base end side of the lens 4 and captures the state of the furnace interior 11 based on the light guided by the lens 4. As the camera 3, for example, a CCD camera or the like is used. The lens 4 and the cover 5 are arranged with their respective central axes C aligned. An opening 51 for passing light is formed at the tip of the cover 5. The attachment 6 is detachably attached to the tip of the cover 5 so as to surround the periphery of the opening 51 of the cover 5.

[0016] In this monitoring device 100, a second vent hole 52 for introducing dust-proof second sealing air A2 into the interior of the cover 5 is formed. The second sealing air A2 introduced from the second vent hole 52 flows from the base end side toward the tip end side through the gap between the outer peripheral surface of the lens 4 and the inner peripheral surface of the cover 5, and is discharged from the opening 51 formed at the tip of the cover 5. The second sealing air A2 prevents dust generated in the furnace interior 11 from adhering to the surface of the monitoring device 100 facing the furnace interior 11, and cools the lens 4 to prevent the temperature of the lens 4 from rising excessively.

[0017] In the monitoring device 100, the first sealing air A1 and the second sealing air A2 prevent dust generated in the furnace interior 11 from adhering to the monitoring device 100. However, it is not possible to completely prevent dust from adhering, and dust may adhere to the surface of the monitoring device 100 facing the furnace interior 11. When dust adheres to the monitoring device 100, there is a possibility that a part of the field of view of the captured image of the camera 3 is missing, making it difficult to appropriately monitor the state of the furnace interior 11.

[0018] Therefore, the monitoring device 100 is equipped with a plasma actuator, and by removing the dust adhering to the monitoring device 100 by dielectric barrier discharge (DBD) by the plasma actuator, it improves the reduction of the field of view due to dust adhesion.

[0019] In the example of FIG. 1, the monitoring device 100 is attached to the furnace wall 12 at an angle where the central axis C intersects the furnace wall 12 vertically. However, the monitoring device 100 may be attached to the furnace wall 12 at an angle where the central axis C intersects the furnace wall 12 obliquely.

[0020] (Configuration of the monitoring device) Next, with reference to FIGS. 2 and 3, the main part of the monitoring device 100 according to the present embodiment will be specifically described. FIG. 2 is a cross-sectional view showing the main part of the monitoring device 100 shown in FIG. 1. FIG. 3 is a front view of the monitoring device 100 shown in FIG. 1 as viewed from the tip side. As shown in FIGS. 2 and 3, in the monitoring device 100, an attachment 6 is attached to the tip side of a cover 5 that covers the outer peripheral surface of the lens 4. The first electrode 71 and the second electrode 72 of the plasma actuator 7 are disposed on the attachment 6.

[0021] The lens 4 is a substantially cylindrical lens tube. The lens 4 has a function of adjusting the focal position of light so that a clear image can be captured by the camera 3. The lens 4 may have a configuration in which, for example, a plurality of lenses are combined.

[0022] The cover 5 is a cylindrical member having conductivity. The cover 5 is composed of, for example, a metal tube such as SUS. The cover 5 is disposed so as to cover substantially the entire length from the tip side to the base end side of the lens 4. The tip of the cover 5 is curved toward the central axis C, and a circular opening 51 having a center on the central axis C is formed at this tip. The opening 51 is formed to have a smaller diameter than the inner diameter of the cover 5. In this way, by relatively reducing the opening area of the opening 51, it becomes difficult for the dust D generated in the furnace 11 to enter the inside of the cover 5 through the opening 51. An inclined surface 53 inclined toward the base end side with respect to the central axis C is formed on the peripheral edge portion surrounding the opening 51.

[0023] The attachment 6 is a fixture for attaching the plasma actuator 7 to the cover 5. In the present embodiment, the attachment 6 is made of a dielectric (insulator). Examples of the dielectric (insulator) include machinable ceramics, high-temperature co-fired ceramics (HTCC), low-temperature co-fired ceramics (LTCC), or laminated packages thereof, or sapphire glass. The attachment 6 is composed of two members: a cylindrical tubular portion 61 that fits onto the outer peripheral surface of the cover 5, and a disk-shaped tip wall 62 provided on the tip end side of the tubular portion 61. A circular opening 63 having a center on the central axis C is formed in the tip wall 62. The opening 63 of the attachment 6 is formed to have a larger diameter than the opening 51 of the cover 5 so that the inclined surface 53 of the cover 5 is exposed at the tip end of the monitoring device 100. Light from the furnace interior 11 enters the lens 4 through the opening 63 of the attachment 6 and the opening 51 of the cover 5.

[0024] The plasma actuator 7 is a device that generates plasma P and an induced jet (jet) F by dielectric barrier discharge. The plasma actuator 7 includes a first electrode 71 and a second electrode 72. Each of the first electrode 71 and the second electrode 72 is annular (ring-shaped) and is arranged to have a center on the central axis C. The first electrode 71 is formed to have a larger diameter than the second electrode 72, and the inner diameter of the first electrode 71 is substantially equal to the outer diameter of the second electrode 72.

[0025] The first electrode 71 and the second electrode 72 may have one or more gaps (gaps) in a part thereof. For example, when the electrodes are separated into segments by a plurality of gaps, an electrode arranged in an annular shape as a whole can be formed by keeping each segment at the same potential. As a remarkable effect of segmenting the electrodes in this way, an induced jet flow F that swirls around the central axis C can be generated by arranging each electrode with the position of the gap shifted by a certain angle in the circumferential direction of the central axis C. Note that the first electrode 71 and the second electrode 72 are not limited to a circular annular shape. The first electrode 71 and the second electrode 72 may have an annular shape other than a circle, such as a polygon.

[0026] The first electrode 71 and the second electrode 72 are arranged with the tip wall 62 of the attachment 6 interposed therebetween. The first electrode 71 is arranged on the surface 6a on the tip side of the tip wall 62 of the attachment 6. Note that the first electrode 71 may be arranged with a part or all thereof embedded in the attachment 6. The second electrode 72 is arranged on the back surface 6b on the base end side (opposite to the surface 6a) of the tip wall 62 of the attachment 6. More specifically, the second electrode 72 is arranged on the back surface 6b in a state of being in contact with the tip of the cover 5 in a gap formed between the cover 5 and the attachment 6.

[0027] These first electrode 71 and second electrode 72 are electrically connected to an AC power source PS. The AC power source PS is a power source capable of outputting a high voltage, such as a sine wave or a pulse wave, at a high frequency. In the illustrated example, the first electrode 71 is electrically connected to the AC power source PS via the first wiring L1. One end of the first wiring L1 is connected to the AC power source PS, and the other end is connected to the first electrode 71 through a through hole 64 for wiring formed in the attachment 6. The second electrode 72 is electrically connected to the AC power source PS via the conductive cover 5 and the second wiring L2. One end of the second wiring L2 is connected to the AC power source PS, and the other end is connected to the cover of the conductive cover 5.

[0028] Note that it is not essential to form a through hole 64 for passing the first wiring L1 through the attachment 6. In this case, the other end of the first wiring L1 may be connected to the first electrode 71 through the outside of the attachment 6, and the first electrode 71 and the AC power supply PS may be electrically connected.

[0029] The plasma actuator 7 is arranged such that the annular first electrode 71 and the annular second electrode 72 are disposed with the tip wall 62 of the attachment 6 made of a dielectric therebetween as described above. Therefore, by applying a high-frequency voltage by the AC power supply PS, dielectric barrier discharge occurs along the surface 6a of the attachment 6. As a result, plasma P is generated near the inner diameter side edge of the annular first electrode 71. Further, charged particles resulting from the generation of the plasma P are accelerated by the electric field, and the surrounding air is induced, thereby generating an induced jet F directed toward the central axis C.

[0030] The plasma actuator 7 removes the dust D attached to the monitoring device 100 by at least one of the plasma P and the induced jet F due to dielectric barrier discharge. For example, the plasma actuator 7 decomposes the dust D attached to the monitoring device 100 by the plasma P due to dielectric barrier discharge. Further, the plasma actuator 7 scatters the dust D attached to the monitoring device 100 by the induced jet F due to dielectric barrier discharge. Alternatively, the plasma actuator 7 decomposes and scatters the dust D attached to the monitoring device 100 by both the plasma P and the induced jet F due to dielectric barrier discharge.

[0031] Therefore, according to the plasma actuator 7, it is possible to remove the dust D that could not be dealt with conventionally, and it is possible to improve the reduction in the field of view of the monitoring device 100 due to the adhesion of the dust D.

[0032] In the above description, an example in which the attachment 6 made of a dielectric is composed of two members, i.e., the cylindrical portion 61 and the tip wall 62, has been shown. However, the attachment 6 may be composed of one member in which the cylindrical portion 61 and the tip wall 62 are integrally formed. Further, in order for the plasma actuator 7 to generate dielectric barrier discharge, at least the tip wall 62 needs to be made of a dielectric having high insulation. For this reason, the cylindrical portion 61 may be made of a material other than a dielectric having high insulation. Thereby, the manufacturing cost of the attachment 6 can be reduced.

[0033] (Control of Monitoring Device) Next, an example of the control of the monitoring device 100 will be described. The monitoring device 100 may control the plasma actuator 7 to continuously or intermittently generate dielectric barrier discharge. Further, the monitoring device 100 may generate dielectric barrier discharge according to the adhesion state of the dust D or the amount of generation of the dust D or the like.

[0034] For example, when the monitoring device 100 processes the captured image by the camera 3 and determines that the dust D adheres to the captured image, the monitoring device 100 may generate dielectric barrier discharge.

[0035] Further, the monitoring device 100 may detect the amount of waste input into the furnace 1, the grate speed, the evaporation amount, etc. with a sensor, predict the amount of fly ash generation according to the detected value, and generate dielectric barrier discharge.

[0036] Further, the monitoring device 100 may adjust the strength, frequency, and direction of the air flow (induced jet F) of the dielectric barrier discharge current according to the degree and position of the adhesion of the dust D.

[0037] Further, the monitoring device 100 may include a plurality of first electrodes 71 so as to maximize the induced jet F, and adjust the generation timing of the dielectric barrier discharge.

[0038] (Effect of Monitoring Device) As described above, the monitoring device 100 according to the present embodiment includes a lens 4 that guides light from the furnace interior 11 to the camera 3, a cylindrical cover 5 that covers the outer peripheral surface of the lens 4 and has an opening 51 that allows light to pass through at the tip on the furnace interior 11 side, and a first electrode 71 that generates at least one of the plasma P generated by dielectric barrier discharge and the induced jet F induced by the plasma P toward the central axis C of the cover 5. The monitoring device 100 further includes a plasma actuator 7 that removes dust D adhering to the surface of the monitoring device 100 facing the furnace interior 11 by at least one of the plasma P and the induced jet F.

[0039] In the monitoring device 100, in order to remove the dust D adhering to the monitoring device 100 by dielectric barrier discharge, it is possible to remove the dust D that could not be dealt with heretofore. Therefore, according to the present embodiment, it is possible to realize a monitoring device 100 that can improve the deterioration of the field of view due to the adhesion of dust D without performing frequent maintenance.

[0040] In the monitoring device 100, the first electrode 71 is preferably disposed at the opening 51 of the cover 5 or on the furnace interior 11 side of the opening 51. Thereby, dielectric barrier discharge can be generated particularly at the opening 51 of the cover 5 or in the vicinity thereof where the dust D is likely to adhere, and the dust D can be removed.

[0041] In the monitoring device 100, it is preferable that the plasma actuator 7 has an annular first electrode 71 disposed concentrically with the opening 51 of the cover 5. Thereby, dielectric barrier discharge can be generated in the vicinity of the opening 51 of the cover 5 to remove the dust D.

[0042] In the monitoring device 100, the plasma actuator 7 is preferably provided on the attachment 6. Thereby, the attachment and detachment of the plasma actuator 7 to and from the cover 5 become easy, and the maintainability of the monitoring device 100 is improved.

[0043] Further, in the monitoring device 100, the attachment 6 is preferably made of a dielectric. Thereby, the attachment 6 can function as the dielectric necessary for dielectric barrier discharge. Therefore, the number of parts of the monitoring device 100 (plasma actuator 7) can be reduced, and the device configuration can be simplified.

[0044] (Modification example) FIG. 4 is a cross-sectional view showing a main part of a monitoring device 100a which is a modification example of the monitoring device 100 shown in FIG. 2. As shown in FIG. 4, in the monitoring device 100a, the tip end side of the cover 5 is not bent toward the central axis C side, and an opening 51 having the same diameter as the inner diameter of the cover 5 is formed at the tip end.

[0045] The attachment 6 is composed of one member in which a cylindrical portion 61 and a tip wall 62 are integrally formed. The opening 63 of the attachment 6 is formed to have a smaller diameter than the opening 51 of the cover 5. An inclined surface 65 inclined toward the base end side with respect to the central axis C is formed on the surface 6a of the attachment 6 at the peripheral edge portion surrounding the opening 63. Further, an annular projection 66 protruding toward the lens 4 side (base end side) is formed on the back surface 6b of the attachment 6 at the peripheral edge portion surrounding the opening 63. The second electrode 72 is disposed on the back surface 6b at a portion excluding the annular projection 66. Further, a refractory insulating pad 8 is disposed so as to cover a portion of the second electrode 72 located on the annular projection 66 side.

[0046] Here, when dielectric barrier discharge is generated by the plasma actuator 7, surface discharge occurs along the surface 6a of the attachment 6. For this reason, if the creepage distance between the first electrode 71 and the second electrode 72 is short, there is a possibility that the first electrode 71 and the second electrode 72 may be short-circuited. Therefore, in order to prevent short-circuiting, it is preferable to ensure as large a creepage distance as possible between the first electrode 71 and the second electrode 72. However, it is assumed that the creepage distance between the first electrode 71 and the second electrode 72 cannot be sufficiently ensured due to problems such as the arrangement space.

[0047] Therefore, the monitoring device 100a includes the annular protrusion 66 and the insulating pad 8, which prevent a short circuit between the first electrode 71 and the second electrode 72. Thereby, without increasing the size of the device configuration of the monitoring device 100a, a short circuit between the first electrode 71 and the second electrode 72 can be suitably prevented.

[0048] FIG. 5 is a cross-sectional view showing a main part of a monitoring device 100b, which is a modified example of the monitoring device 100a shown in FIG. 4. As shown in FIG. 5, in the monitoring device 100b, the second electrode 72 is disposed across between the cover 5 and the attachment 6, and a part of the second electrode 72 is exposed on the outer peripheral surface of the cover 5. For this reason, in the monitoring device 100b, the second electrode 72 and the AC power supply PS are directly connected by the second wiring L2 without passing through the cover 5, so that the second electrode 72 and the AC power supply PS are electrically connected. Therefore, in the monitoring device 100b, there is no need for the cover 5 to have conductivity, and the cover 5 can be made of a material having no conductivity.

[0049] FIG. 6 is a cross-sectional view showing a main part of a monitoring device 100c, which is a modified example of the monitoring device 100 shown in FIG. 2. As shown in FIG. 6, in the monitoring device 100c, the tip side of the cover 5 is bent at an angle of approximately 90 degrees toward the central axis C side. For this reason, when the attachment 6 is attached to the tip of the cover 5, a gap is hardly formed between the cover 5 and the attachment 6.

[0050] In the monitoring device 100c, the conductive cover 5 functions as the second electrode 72. Thereby, there is no need to dispose the second electrode 72 on the attachment 6, the number of components of the monitoring device 100 can be reduced, and the device configuration can be simplified.

[0051] Note that, generally, plasma P is more likely to be generated as the gas density is lower. Since the inside of the cover 5 has a relatively higher gas density than the outside (inside the furnace 11), the environment is often such that plasma P is less likely to be generated. For this reason, the risk of the induced jet flow F induced by the plasma P flowing into the inside of the cover 5 may be reduced depending on the internal pressure of the cover 5. Therefore, it is not essential to arrange the insulating pate 8. However, arranging the insulating pate 8 as a precaution in case the induced jet flow F does flow in is preferable from the viewpoint of more surely preventing a short circuit.

[0052] 〔Embodiment 2〕 Other embodiments of the present invention will be described below. For convenience of explanation, members having the same functions as those described in the above embodiment are denoted by the same reference numerals, and their explanations will not be repeated.

[0053] (Configuration of the monitoring device) FIG. 7 is a cross-sectional view showing the main part of the monitoring device 101 according to the present embodiment. The monitoring device 101 is mainly different from the above-described monitoring device in that the cover 5 is ceramic-coated.

[0054] As shown in FIG. 7, in the monitoring device 101, the conductive cover 5 functions as the second electrode 72. A ceramic layer 54 is formed on the surface of the cover 5. By coating the cover 5 with the ceramic layer 54, a short circuit between the first electrode 71 and the cover 5 due to dielectric barrier discharge is prevented.

[0055] Note that the ceramic layer 54 may be formed only at the tip and its vicinity of the cover 5. When dielectric barrier discharge is generated, surface discharge occurs along the surface 6a of the attachment 6. For this reason, even if the ceramic layer 54 is formed only at the tip and its vicinity of the cover 5, a short circuit between the first electrode 71 and the cover 5 due to dielectric barrier discharge can be prevented.

[0056] (Effect of the monitoring device) As described above, in the monitoring device 101 according to this embodiment, the ceramic layer 54 is formed on the cover 5. Therefore, when the conductive cover 5 functions as the second electrode 72 of the plasma actuator 7, a short circuit due to dielectric barrier discharge is prevented. Accordingly, the safety of the monitoring device 101 can be enhanced.

[0057] [Embodiment 3] Other embodiments of the present invention will be described below. For convenience of explanation, members having the same functions as the members described in the above embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

[0058] (Configuration of Monitoring Device) FIG. 8 is a cross-sectional view showing a main part of the monitoring device 102 according to this embodiment. FIG. 9 is an enlarged schematic view of the vicinity of the opening 51 of the monitoring device 102 shown in FIG. 8. FIG. 10 is a schematic view of the monitoring device 102 shown in FIG. 8 as viewed from the tip end side. The monitoring device 102 is mainly different from the above-described monitoring device in that the attachment 6 is integrally formed with the cover 5.

[0059] As shown in FIGS. 8 to 10, in the monitoring device 102, the attachment 6 is integrally formed with the cover 5, and the plasma actuator 7 is mounted on the cover 5. The cover 5 is made of a highly insulating dielectric (material having insulating properties) such as sapphire glass. On the tip end side of the cover 5, a first accommodation recess 55 and a second accommodation recess 56 are formed from the outer peripheral surface of the cover 5 toward the opening 51 at positions facing each other with the opening 51 interposed therebetween. The bottoms (inner ends) 55a and 56a of the first accommodation recess 55 and the second accommodation recess 56 face each other with the opening 51 interposed therebetween.

[0060] The plasma actuator 7 includes a plate-shaped first electrode 71 and a plate-shaped second electrode 72. The first electrode 71 is accommodated in the bottom 55a of the first accommodation recess 55. The second electrode 72 is accommodated in the bottom 56a of the second accommodation recess 56. The first electrode 71 and the second electrode 72 face each other with the opening 63 (central axis C) interposed therebetween.

[0061] The plasma actuator 7 has a first electrode 71 and a second electrode 72 disposed with a cover 5 made of a dielectric therebetween. Therefore, by applying a high-frequency voltage by an AC power supply PS, dielectric barrier discharge occurs between the first electrode 71 and the second electrode 72, generating plasma P. Thereby, the dust D adhering to the opening 51 of the cover 5 can be removed.

[0062] Note that texturing may be performed to form irregularities on the surfaces of the first electrode 71 and the second electrode 72. Thereby, dielectric barrier discharge can be generated more uniformly.

[0063] Also, the cover 5 may be made of a material other than sapphire glass. The cover 5 may be made of, for example, quartz glass or machinable ceramic, etc. Thereby, the manufacturing cost of the cover 5 can be reduced.

[0064] Also, the length D of the opening 51 (the first electrode 71 and the second electrode 72) of the cover 5 in the central axis C direction h If it is too large, it may affect the captured image by the camera 3. Therefore, the length D h is appropriately set to a size that does not affect the captured image.

[0065] Also, if the distance D between the first electrode 71 and the second electrode 72 s is too large, it becomes necessary to apply a high voltage to generate dielectric barrier discharge. Therefore, the distance D s is appropriately set based on the dimensions of the opening 51, the applied voltage, etc.

[0066] (Effect of the monitoring device) As described above, in the monitoring device 102 according to the present embodiment, the first electrode 71 and the second electrode 72 are arranged with the opening 51 (central axis C) of the cover 5 therebetween. Therefore, according to the monitoring device 102, dust D adhering to the opening 51 of the cover 5 can be removed by dielectric barrier discharge. Further, according to the monitoring device 102, the attachment 6 can be omitted, so that the number of components of the monitoring device 102 can be reduced and the device configuration can be simplified.

[0067] 〔Embodiment 4〕 Other embodiments of the present invention will be described below. For convenience of explanation, members having the same functions as those described in the above embodiments are denoted by the same reference numerals, and the description thereof will not be repeated.

[0068] (Configuration of Monitoring Device) FIG. 11 is a cross-sectional view showing a main part of the monitoring device 103 according to the present embodiment. FIG. 12 is a schematic view of the monitoring device 103 shown in FIG. 11 as viewed from the tip side. The monitoring device 103 is mainly different from the above-described monitoring device in that the first electrode 71 and the second electrode 72 are embedded in the attachment 6.

[0069] In the monitoring device 103, the cover 5 is made of metal, and the attachment 6 is made of machinable ceramic. As shown in FIGS. 11 and 12, circular first accommodation recess 67 and second accommodation recess 68 are formed in the tip wall 62 of the attachment 6 at positions facing each other with the opening 63 therebetween, extending from the outer peripheral surface of the attachment 6 toward the opening 63. The bottom portions (inner portions) 67a and 68a of the first accommodation recess 67 and the second accommodation recess 68 face each other with the opening 63 therebetween.

[0070] The plasma actuator 7 includes a columnar first electrode 71 and a columnar second electrode 72. The first electrode 71 is inserted into a bottomed cylindrical sapphire glass tube 73 made of sapphire glass. The first electrode 71 is housed in the first housing recess 67 in a state of being inserted into the sapphire glass tube 73. Further, the second electrode 72 is housed in the second housing recess 68. The first electrode 71 and the second electrode 72 face each other with the opening 63 (central axis C) interposed therebetween.

[0071] The plasma actuator 7 has the first electrode 71 and the second electrode 72 disposed with the sapphire glass tube 73 and the attachment 6 made of machinable ceramic interposed therebetween. Therefore, by applying a high-frequency voltage by the AC power supply PS, dielectric barrier discharge occurs between the first electrode 71 and the second electrode 72, and plasma P is generated. Thereby, the dust D adhering to the opening 51 of the cover 5 can be removed.

[0072] Note that a sapphire glass tube 73 may be attached not only to the first electrode 71 but also to the second electrode 72. However, by not attaching the sapphire glass tube 73 to the second electrode 72, the distance D s between the first electrode 71 and the second electrode 72 becomes small. Therefore, the voltage for generating dielectric barrier discharge can be suppressed.

[0073] (Effect of the monitoring device) As described above, in the monitoring device 103 according to the present embodiment, the plasma actuator 7 includes the columnar first electrode 71 and the columnar second electrode 72, and the first electrode 71 and the second electrode 72 are disposed with the opening 51 (central axis C) of the cover 5 interposed therebetween. Therefore, according to the monitoring device 103, the dust D adhering to the opening 51 of the cover 5 can be removed by dielectric barrier discharge.

[0074] 〔Embodiment 5〕 Other embodiments of the present invention will be described below. For convenience of explanation, members having the same functions as those described in the above embodiments are denoted by the same reference numerals, and the description thereof will not be repeated.

[0075] (Configuration of the monitoring device) FIG. 13 is a cross-sectional view showing a main part of the monitoring device 104 according to the present embodiment. FIG. 14 is a schematic view when the monitoring device 104 shown in FIG. 13 is viewed from the tip side. The monitoring device 104 is mainly different from the above-described monitoring device in that the first electrode 71 is composed of a string-shaped metal wire.

[0076] As shown in FIGS. 13 and 14, in the monitoring device 104, the plasma actuator 7 includes two first electrodes 71 composed of string-shaped metal wires. Each of the first electrodes 71 is inserted into a cylindrical sapphire glass tube 73 made of sapphire glass. One end of the sapphire glass tube 73 is closed by an insulating plate 8. Note that, instead of the sapphire glass tube 73, an insulating tube made of a material having insulation properties such as ceramics can also be used.

[0077] These first electrodes 71 are arranged in parallel with each other on the surface 5a on the tip side of the cover 5 with the opening 51 (central axis C) interposed therebetween. Therefore, by applying a high-frequency voltage by the AC power supply PS, dielectric barrier discharge occurs along the surface 5a of the cover 5, and plasma P is generated in the vicinity of each side surface of the string-shaped first electrode 71. Further, by inducing the surrounding air by the plasma P, an induced jet F directed toward the central axis C and an induced jet F directed to the side opposite to the central axis C are generated. Thereby, the dust D adhering to the opening 51 of the cover 5 can be removed.

[0078] (Effect of the monitoring device) As described above, in the monitoring device 104 according to the present embodiment, the plasma actuator 7 includes two linear first electrodes 71, and these two first electrodes 71 are arranged with the opening 51 (central axis C) of the cover 5 interposed therebetween. Therefore, according to the monitoring device 104, the dust D adhering to the opening 51 of the cover 5 can be removed by dielectric barrier discharge.

[0079] (Modification) FIG. 15 is a cross-sectional view showing a main part of a monitoring device 104a which is a modified example of the monitoring device 104 shown in FIG. 13. As shown in FIG. 15, in the monitoring device 104a, an insulating plate 8 is further provided outside two first electrodes 71 facing each other across the opening 51 (central axis C) of the cover 5 with a sapphire glass tube 73 interposed therebetween. By providing this insulating plate 8, dielectric barrier discharge is inhibited from occurring on the side opposite to the opening 51 (central axis C) of the cover 5, so that dielectric barrier discharge can be generated toward the opening 51 (central axis C).

[0080] 〔Embodiment 6〕 Other embodiments of the present invention will be described below. For the sake of convenience of explanation, members having the same functions as those described in the above embodiments are denoted by the same reference numerals, and their descriptions will not be repeated.

[0081] (Configuration of Monitoring Device) FIG. 16 is a cross-sectional view showing a main part of a monitoring device 105 according to the present embodiment. The monitoring device 105 is mainly different from the above-described monitoring device in that the first electrode 71 is composed of a coiled metal wire.

[0082] As shown in FIG. 16, in the monitoring device 102, the attachment 6 includes an annular accommodation recess 69 formed so as to protrude from its surface 6a into the furnace 11. The accommodation recess 69 opens in a direction opposite to the opening 63 (central axis C) and is provided annularly so as to surround the opening 63. The attachment 6 is made of a dielectric such as machinable ceramic or sapphire glass.

[0083] The plasma actuator 7 includes a first electrode 71 composed of a coiled metal wire. The coiled first electrode 71 is disposed in the accommodation recess 69 such that it is wound around the bottom (inner part) 69a of the accommodation recess 69 of the attachment 6. That is, the coiled first electrode 71 is disposed so as to surround the opening 51 (central axis C) of the cover 5. Therefore, by applying a high-frequency voltage by the AC power supply PS, dielectric barrier discharge occurs along the surface 6a of the attachment 6, and plasma P is generated in the vicinity of the inner diameter side of the coiled first electrode 71. Further, by inducing the surrounding air by the plasma P, an induced jet F directed toward the central axis C is generated. Thereby, the dust D adhering to the opening 51 of the cover 5 can be removed.

[0084] (Effect of the monitoring device) As described above, in the monitoring device 105 according to the present embodiment, the plasma actuator 7 includes the coiled first electrode 71, and the coiled first electrode 71 is disposed so as to surround the opening 51 of the cover 5. Therefore, according to the monitoring device 105, the dust D adhering to the opening 63 of the attachment 6 can be removed by dielectric barrier discharge.

[0085] (Modification) FIG. 17 is a cross-sectional view showing a main part of a monitoring device 105a which is a modification of the monitoring device 105 shown in FIG. 16. As shown in FIG. 17, in the monitoring device 105a, the accommodation recess 69 of the attachment 6 is made of a material different from the other parts (cylindrical part 61 and tip wall 62) of the attachment 6. For example, the attachment 6 has a hybrid structure in which the accommodation recess 69 is made of sapphire glass and the parts other than the accommodation recess 69 are made of machinable ceramic. Thus, by forming the parts other than the accommodation recess 69 of machinable ceramic, the manufacturing cost of the attachment 6 can be reduced.

[0086] 〔Embodiment 7〕 Other embodiments of the present invention will be described below. For the sake of convenience of explanation, members having the same functions as those described in the above embodiments are denoted by the same reference numerals, and the description thereof will not be repeated.

[0087] (Configuration of Monitoring Device) FIG. 18 is a cross-sectional view showing a main part of a monitoring device 106 according to the present embodiment. The monitoring device 106 is mainly different from the above-described monitoring device in that the opening 63 of the attachment 6 is closed by the dielectric 9.

[0088] As shown in FIG. 18, in the monitoring device 106, the plasma actuator 7 includes a dielectric 9. The central portion of the dielectric 9 is transparent to secure the field of view of the lens 4. On the dielectric 9, two first electrodes 71 and two second electrodes 72 are alternately arranged in the direction of the central axis C. The two sets of first electrodes 71 and second electrodes 72 are arranged, for example, on the tip side and the base end side of the dielectric 9 so as to surround the periphery of the dielectric 9. The dielectric 9 is arranged so as to close the opening 63 of the attachment 6. For this reason, an exhaust port 60 is formed in the peripheral wall of the attachment 6, and the second sealing air A2 is discharged from the exhaust port 60.

[0089] Further, the monitoring device 106 includes a blower B for spraying an air flow along the tip side of the opening 63 of the attachment 6. The blower B scatters dust D that cannot be removed by the induced jet F due to dielectric barrier discharge of the plasma actuator 7.

[0090] In the plasma actuator 7, each of the first electrode 71 and the second electrode 72 is arranged with the dielectric 9 interposed therebetween. Therefore, by applying a high-frequency voltage by the AC power supply PS, dielectric barrier discharge occurs, and plasma P is generated between each of the first electrode 71 and the second electrode 72.

[0091] (Effect of Monitoring Device) As described above, in the monitoring device 106 according to the present embodiment, the dielectric 9 is disposed so as to close the opening 63 of the attachment 6. Therefore, according to the monitoring device 106, the dust D generated in the furnace 11 is less likely to enter the inside of the monitoring device 106, and it is possible to prevent the dust D from adhering to the lens 4 and the cover 5.

[0092] 〔Embodiment 8〕 Another embodiment of the present invention will be described below. For convenience of explanation, members having the same functions as those described in the above embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

[0093] (Configuration of Monitoring Device) FIG. 19 is a cross-sectional view showing a main part of a monitoring device 107 according to the present embodiment. The monitoring device 107 is mainly different from the above-described monitoring device in that the first electrode 71 and the second electrode 72 are disposed on the peripheral wall of the cover 5.

[0094] As shown in FIG. 19, in the monitoring device 107, the plasma actuator 7 includes a columnar first electrode 71 and a columnar second electrode 72. The first electrode 71 is inserted into a bottomed cylindrical sapphire glass tube 73 made of sapphire glass. The first electrode 71 is inserted into the sapphire glass tube 73 and penetrates the peripheral wall 57 of the cover 5 in the thickness direction. The second electrode 72 also penetrates the peripheral wall 57 of the cover 5 in the thickness direction. The first electrode 71 and the second electrode 72 are disposed at positions facing each other with the lens 4 interposed therebetween. Therefore, by applying a high-frequency voltage by the AC power supply PS, dielectric barrier discharge occurs, and plasma P is generated between the first electrode 71 and the second electrode 72. Further, by inducing the surrounding air by the plasma P, an induced jet flow F from the first electrode 71 toward the lens 4 is generated. Thereby, the dust D adhering to the tip of the lens 4 can be removed by the dielectric barrier discharge.

[0095] Note that the shapes of the first electrode 71 and the second electrode 72 are not limited to columnar shapes. The first electrode 71 and the second electrode 72 may have shapes other than columnar shapes, such as plate shapes. Also, in the monitoring device 107, the conductive cover 5 may function as the second electrode 72.

[0096] (Effect of the monitoring device) As described above, in the monitoring device 107 according to the present embodiment, the first electrode 71 and the second electrode 72 are disposed on the peripheral wall of the cover 5 that covers the outer peripheral surface of the lens 4, and are disposed opposite to each other with the lens 4 interposed therebetween. Therefore, according to the monitoring device 107, dielectric barrier discharge can be generated inside the cover 5, and dust D that has entered inside the cover 5 and adhered to the lens 4 can be removed by the dielectric barrier discharge.

[0097] 〔Embodiment 9〕 Other embodiments of the present invention will be described below. For the sake of convenience of explanation, members having the same functions as those described in the above embodiments are denoted by the same reference numerals, and their descriptions will not be repeated.

[0098] (Configuration of the monitoring device) FIG. 20 is a cross-sectional view showing a main part of a monitoring device 108 according to the present embodiment. FIG. 21 is a schematic view of the monitoring device 108 shown in FIG. 20 as viewed from the tip end side. The monitoring device 108 is mainly different from the above-described monitoring device in that it includes a dielectric plate 10 made of a dielectric (insulator).

[0099] As shown in FIG. 20, in the monitoring device 108, the plasma actuator 7 includes an annular dielectric plate 10. The dielectric plate 10 is made of a dielectric (insulator) such as machinable ceramic or sapphire glass. The dielectric plate 10 is annular (ring-shaped) with a center on the central axis C and is installed in the opening 51 of the cover 5.

[0100] Each of the first electrode 71 and the second electrode 72 is annular (ring-shaped) and is arranged so as to have its center on the central axis C. The first electrode 71 is formed with a larger diameter than the second electrode 72, and the inner diameter of the first electrode 71 is substantially equal to the outer shape of the second electrode 72.

[0101] The first electrode 71 and the second electrode 72 are arranged with the dielectric plate 10 therebetween. The first electrode 71 is arranged on the surface 10a on the tip side of the dielectric plate 10, and the second electrode 72 is arranged on the back surface 10b on the base end side (opposite to the surface 10a) of the dielectric plate 10.

[0102] The plasma actuator 7 is arranged such that the annular first electrode 71 and the annular second electrode 72 are arranged with the dielectric plate 10 therebetween as described above. Therefore, by applying a high-frequency voltage by the AC power supply PS, dielectric barrier discharge occurs along the surface 10a of the dielectric plate 10, and plasma P is generated near the inner diameter side edge of the annular first electrode 71. Further, by inducing the surrounding air by the plasma P, an induced jet F directed toward the central axis C is generated.

[0103] For this reason, according to the plasma actuator 7, it becomes possible to remove dust D that could not be dealt with conventionally, and it is possible to improve the reduction of the visual field of the monitoring device 100 due to the adhesion of dust D.

[0104] (Effect of the monitoring device) As described above, in the monitoring device 108 according to the present embodiment, the first electrode 71 and the second electrode 72 are arranged to face each other with the dielectric plate 10 interposed therebetween on the dielectric plate 10 installed in the opening 51 of the cover 5. Therefore, according to the monitoring device 108, dielectric barrier discharge can be generated particularly in the opening 51 of the cover 5 where dust D is likely to adhere, and the dust D can be removed.

[0105] [Embodiment 10] Other embodiments of the present invention will be described below. For convenience of explanation, members having the same functions as those described in the above embodiments are denoted by the same reference numerals, and the description thereof will not be repeated.

[0106] (Configuration of the monitoring device) FIG. 22 is a cross-sectional view showing the main part of the monitoring device 109 according to the present embodiment. The monitoring device 109 is mainly different from the above-described monitoring device in that the first wiring L1 and the second wiring L2 are arranged inside the inner peripheral surface or the peripheral wall of the attachment 6.

[0107] As shown in FIG. 22, in the monitoring device 109, the first wiring L1 that electrically connects the first electrode 71 and the AC power supply PS is spirally arranged on the inner peripheral surface of the attachment 6 made of an insulator. Further, the second wiring L2 that electrically connects the second electrode 72 and the AC power supply PS is spirally arranged on the inner peripheral surface of the cylindrical attachment 6. Thereby, the first wiring L1 and the second wiring L2 are arranged in a double spiral shape on the inner peripheral surface of the attachment 6.

[0108] In this way, since the first wiring L1 and the second wiring L2 are arranged on the inner peripheral surface of the attachment 6, for example, processing for forming a through hole 64 (see FIG. 2) for wiring in the attachment 6 becomes unnecessary. Further, it becomes unnecessary to wire the first wiring L1 and the second wiring L2 through the outside of the attachment 6, and the first wiring L1 and the second wiring L2 are not exposed outside the monitoring device 109.

[0109] (Effect of the monitoring device) As described above, in the monitoring device 109 according to the present embodiment, the first wiring L1 and the second wiring L2 are arranged inside the inner peripheral surface or the peripheral wall of the attachment 6. Therefore, according to the monitoring device 109, the processing of the attachment 6 becomes easy and the safety of the monitoring device 109 can be improved.

[0110] [Embodiment 11] Other embodiments of the present invention will be described below. For convenience of explanation, members having the same functions as the members described in the above embodiments are denoted by the same reference numerals, and the description thereof will not be repeated.

[0111] (Configuration of the monitoring device) FIG. 23 is a cross-sectional view showing a main part of the monitoring device 110 according to the present embodiment. The monitoring device 110 is mainly different from the above-described monitoring device in that a plurality of plasma actuators 7 are arranged at intervals.

[0112] As shown in FIG. 23, the monitoring device 110 includes a plurality of plasma actuators 7 (four in the example of FIG. 23) including a first electrode 71, a second electrode 72, and a dielectric plate 10. The plurality of plasma actuators 7 are arranged on the attachment 6 so as to have a center on the central axis C. Among the plurality of plasma actuators 7, one is installed on the inner peripheral surface of the opening 63 or near the opening 63 of the attachment 6, and three are installed on the inner peripheral surface of the attachment 6 at intervals in the direction of the central axis C.

[0113] Each electrode of the plasma actuator 7 is electrically connected to an AC power supply PS via a first wiring L1 and a second wiring L2 disposed inside the inner peripheral surface or the peripheral wall of the attachment 6.

[0114] For the three plasma actuators 7 installed on the inner peripheral surface of the attachment 6, the width of the dielectric plate 10 (the radial width of the cover 5) located on the tip side is the smallest, and the width of the dielectric plate 10 located on the base end side is the largest. Thus, the plasma P and the induced jet F due to the dielectric barrier discharge can be more efficiently directed toward the central axis C for the plasma actuator 7 closer to the cover 5.

[0115] (Effect of the monitoring device) As described above, the monitoring device 110 according to the present embodiment includes a plurality of plasma actuators 7. Therefore, according to the monitoring device 110, more dielectric barrier discharges can be generated. Further, according to the monitoring device 110, the generation timing of the dielectric barrier discharge can be adjusted by controlling each plasma actuator 7 so as to maximize the induced jet F.

[0116] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope indicated by the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

Explanation of Reference Numerals

[0117] 3 cameras 4 lenses (light guide section) 5 cover (second electrode) 6 attachment 7 plasma actuator 11 inside the furnace 71 first electrode 72 second electrode 100, 100a to 100c, 101 to 104, 104a, 105, 105a, 106 to 110 monitoring device D dust F induced jet (jet) P plasma

Claims

1. A monitoring device for monitoring the interior of a furnace, comprising: a light guide section that guides light from the interior of the furnace to a camera; a cylindrical cover that covers the circumferential surface of the light guide section and has a cover opening at the tip end portion on the furnace interior side through which the light passes; a plasma actuator that includes a first electrode for generating at least one of plasma generated by dielectric barrier discharge and a jet induced by the plasma, and directing at least one of the plasma and the jet toward the central axis of the cover, and removing dust adhering to the surface of the monitoring device facing the interior of the furnace or the interior of the monitoring device by at least one of the plasma and the jet; an attachment attached to the tip end side and having an opening at a position corresponding to the cover opening; the attachment includes a cylindrical cylindrical portion that fits onto the outer circumferential surface of the cover, and a disk-shaped tip end wall provided on the tip end side of the cylindrical portion and having an attachment opening centered on the central axis formed therein; the plasma actuator further includes a second electrode; the first electrode is disposed on the surface of the tip end side of the tip end wall, and the second electrode is disposed on the back surface opposite to the surface of the tip end wall. A monitoring device.

2. The attachment opening is formed to have a smaller diameter than the cover opening, The monitoring device according to claim 1, wherein the tip end wall protrudes toward the central axis side more than the cover opening.

3. An annular protrusion protruding toward the light guide section side is formed on the back surface of the tip end wall at the peripheral edge of the attachment opening. The monitoring device according to claim 2.

4. A refractory insulating pad is disposed so as to cover a portion of the second electrode located on the attachment opening side. The monitoring device according to claim 2 or 3.

5. The plasma actuator includes the annular first electrode, The monitoring device according to claim 1, wherein the first electrode is disposed concentrically with the cover opening.

6. The plasma actuator includes two of the first electrodes, The monitoring device according to claim 1, wherein the two first electrodes are disposed with the central axis therebetween.

7. The plasma actuator is provided on the attachment. The monitoring device according to any one of claims 1 to 6.

8. The monitoring device according to claim 1, wherein the attachment is made of a dielectric.

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