JP7044485B2 - Plasma reactor - Google Patents

Description

The present invention relates to a plasma reactor, and more particularly to a plasma reactor suitable for an apparatus for purifying exhaust gas of an internal combustion engine (engine).

Conventionally, by passing the exhaust gas from an engine or incinerator through a plasma field, CO (carbon monoxide), HC (hydrocarbon), NOx (nitrogen oxide) and PM (Particulate Matter) contained in the exhaust gas are particulate. A plasma reactor that treats harmful substances such as substances) has been proposed.

For example, in Patent Document 1, a plasma reactor in which a pair of electrodes are arranged in a case and a voltage is applied between adjacent electrodes to generate plasma to remove PM in exhaust gas flowing between the adjacent electrodes. Has been proposed. Further, in Patent Document 2, a laminated body formed by laminating a plurality of electrode panels on which a discharge electrode is formed is housed in a case, and a voltage is applied between adjacent electrode panels to apply a voltage to a low temperature plasma by a dielectric barrier discharge. A plasma reactor has been proposed in which PM in the exhaust gas flowing between the electrode panels is oxidized and removed by generating (non-equilibrium plasma).

Special Table 2003-512167 (Fig. 1 etc.) Japanese Patent No. 3832654 (Fig. 1, Fig. 4, etc.)

By the way, when the plasma reactor is mounted on a vehicle or the like and used, exhaust gas containing soot (PM) flows into the gas flow path of the plasma reactor. The exhaust gas may include water (specifically, condensed exhaust water generated by dew condensation in the exhaust pipe at the time of cold start of the vehicle).

However, in the prior art described in Patent Document 1, since the terminal electrically connected to the electrode is arranged in the gas flow path, the exhaust gas flowing into the gas flow path comes into contact with the terminal and with respect to the terminal. PM and water in the exhaust gas will adhere. As a result, there is a problem that insulation between the terminal and the case cannot be ensured because the terminal (and the electrode) and the case are electrically connected to each other via PM and water. In this case, since a leak current is generated, the amount of plasma generated with respect to the input power is small, and the purification efficiency of the exhaust gas may be low.

Further, in the prior art described in Patent Document 2, a pair of lead line members electrically connected to a discharge electrode is a plasma in which a central portion of a plasma reactor, that is, PM that cannot be completely removed is attached and easily deposited. It will be located near the upstream part of the reactor. As a result, there is a problem that insulation cannot be ensured because the connection between the pair of lead line members and the case where the lead line member and the case in contact with the lead line are easily conducted is easily conducted via PM and water.

The present invention has been made in view of the above problems, and an object thereof is to improve reliability by ensuring insulation between a pair of electrically conductive portions and insulation between an electrically conductive portion and a case. It is to provide a plasma reactor capable of being capable.

As a means (means 1) for solving the above-mentioned problems, it has a structure in which a plurality of electrode panels having an upstream end face into which gas flows in and a downstream end face in which gas flows out and having a discharge electrode are laminated. A plasma reactor comprising a plasma panel laminate that generates plasma when a voltage is applied between adjacent electrode panels and a pair of electrically conductive portions electrically connected to the discharge electrodes of the plurality of electrode panels. The electrically conductive portion is a clamp having a function of sandwiching the plurality of electrode panels in the stacking direction, and is between the case in which the plasma panel laminate is housed and the case and the plasma panel laminate. It has a mat that is interposed and fixes the plasma panel laminate to the case, and a virtual surface is placed at a position in the plasma panel laminate where the distance from the upstream end face and the distance from the downstream end face are equal. When set, the intermediate point of the pair of electrical conduction portions is located on the downstream side of the virtual surface, and a notch portion penetrating the mat in the thickness direction is arranged on the mat, and the inside of the notch portion. There is a plasma reactor characterized in that the electrical conduction portion is located in the region.

Therefore, in the invention described in the above means 1, the intermediate point of the pair of electrical conduction portions is located on the downstream side of the virtual surface set at a position where the distance from the upstream end face and the distance from the downstream end face are equal. is doing. Therefore, when the gas flows into the plasma reactor, it becomes difficult for PM and water in the gas to reach the electrically conductive portion, so that PM in the exhaust gas flowing between the adjacent electrode panels is oxidized and removed by using plasma. In this case, PM and water in the exhaust gas are prevented from adhering to the electrically conductive portion. Further, since the electrically conductive portion is arranged at a location away from the upstream side of the plasma reactor, which is a location where PM in the exhaust gas is likely to be deposited, the deposited PM can be prevented from adhering to the electrically conductive portion. .. As a result, conduction between the pair of electrical conduction portions via PM or water and conduction between the electrical conduction portion via PM or water and the case in which the plasma panel laminate is housed are prevented, so that the pair It is possible to secure the insulation between the electrically conductive portions and the insulation between the electrically conductive portions and the case. Therefore, the reliability of the plasma reactor can be improved.

The plasma panel laminate constituting the plasma reactor has a structure in which a plurality of electrode panels on which discharge electrodes are formed are laminated. Examples of the material for forming the discharge electrode include tungsten (W), molybdenum (Mo), ruthenium oxide (RuO ₂ ), silver (Ag), copper (Cu), platinum (Pt) and the like.

Further, the invention described in the means 3 has a structure in which a plurality of electrode panels having a discharge electrode and a plurality of electrode panels having an upstream end surface into which gas flows in and a downstream end surface in which gas flows out are laminated, and the adjacent electrode panels are adjacent to each other. A plasma reactor comprising a plasma panel laminate that generates plasma when a voltage is applied between them, and a pair of electrically conducting portions electrically connected to the discharge electrodes of the plurality of electrode panels. The electrical conduction portion is a clamp having a function of sandwiching the plurality of electrode panels in the stacking direction, and is virtual at a position where the distance from the upstream end face and the distance from the downstream end face are equal in the plasma panel laminated body. When the surface is set, the intermediate point of the pair of electric conduction portions is located on the downstream side of the virtual surface, and the pair of electrical conduction portions are arranged only in the upper half region of the plasma panel laminate. There is a plasma reactor characterized by being In the invention described in the above means 3, when water flows into the plasma reactor, it becomes difficult for the water to reach the electrically conductive portion that is responsible for energizing each electrode panel, which is caused by the adhesion of water to the electrically conductive portion. It is possible to prevent conduction between a pair of electrical conduction portions and conduction between the electrical conduction portion and the case due to the adhesion of water to the electrical conduction portion. As a result, the insulation between the pair of electrically conductive portions and the insulation between the electrically conductive portions and the case are surely secured, so that the reliability of the plasma reactor is further improved.

It should be noted that a gas flow path through which gas passes from the upstream end face side to the downstream end face side is provided between the adjacent electrode panels, and the electrical conduction portion is configured so as not to be exposed to the gas flow path. good. By doing so, contact of the gas passing through the gas flow path with the electrically conductive portion is prevented, so that PM in the exhaust gas flowing between the adjacent electrode panels is oxidized and removed by using plasma. Adhesion of PM and water in the exhaust gas to the electrically conductive portion can be prevented more reliably. As a result, the conduction between the electrically conductive portion and the case via PM or water is surely prevented, so that the insulation between the electrically conductive portion and the case can be surely secured. Therefore, the reliability of the plasma reactor is further improved.

Further, when the plasma reactor has an electric take-out part that is electrically connected to the electric conductive part, it is preferable that the electric take-out part is located on the downstream side of the virtual surface. By doing so, when the gas flows into the plasma reactor, the PM in the gas and the water are less likely to come into contact with the electricity extraction part, so that the PM in the exhaust gas flowing between the adjacent electrode panels is oxidized by using plasma. When the gas is removed, PM and water in the exhaust gas are prevented from adhering to the electric extraction unit. As a result, the conduction between the electric conduction portion and the case via the electric conduction portion is prevented, so that the insulation between the electric conduction portion and the case can be ensured. Therefore, the reliability of the plasma reactor is further improved.

The invention described in means 2 has a structure in which a plurality of electrode panels having a discharge electrode and a plurality of electrode panels having an upstream end surface into which gas flows in and a downstream end surface in which gas flows out are laminated, and are located between adjacent electrode panels. A plasma reactor including a plasma panel laminate that generates plasma when a voltage is applied and a pair of electrically conducting portions electrically connected to the discharging electrodes of the plurality of electrode panels, wherein the electrical conduction is provided. The portion is a clamp having a function of sandwiching the plurality of electrode panels in the stacking direction, and a virtual surface is placed at a position where the distance from the upstream end face and the distance from the downstream end face are equal in the plasma panel laminated body. When set, the intermediate point of the pair of electrically conducting portions is located on the downstream side of the virtual surface, and there is an electric discharging portion electrically connected to the electrically conducting portion, and the electric discharging portion is formed. There is a plasma reactor characterized in that it is arranged only in the upper half region of the plasma panel laminate. That is, in addition to the electrical conduction portion being arranged in the upper half region of the plasma panel laminate, the electrical extraction portion is also arranged in the upper half region of the plasma panel laminate. According to the invention described in the above means 2, when water flows into the plasma reactor, it becomes difficult for the water to reach the electrically conductive portion and also it becomes difficult for the water to reach the electric extraction portion. Therefore, it is possible to prevent the conduction between the pair of electric conduction portions and the conduction between the electric conduction portions and the case due to the adhesion of water to the electric conduction portion and the electric extraction portion.

Further, the plasma reactor has a case in which the plasma panel laminate is housed and a mat interposed between the case and the plasma panel laminate to fix the plasma panel laminate to the case. A notch that penetrates in the thickness direction is arranged, and an electrically conductive portion is located in the inner region of the notch. In this case, the electrically conductive portion is surrounded by the mat. As a result, when the PM in the exhaust gas flowing between the adjacent electrode panels is oxidized and removed by using plasma, the exhaust gas flowing into the plasma reactor is blocked by the mat, so that the PM in the exhaust gas to the electrically conductive portion is blocked. And water will be prevented from adhering. Therefore, it is possible to prevent the pair of electrically conductive portions from conducting conduction through the mat and the electrical conduction portion and the case from conducting conduction through the mat.

Schematic cross-sectional view showing a plasma reactor in this embodiment. The perspective view which shows the plasma reactor. A side view showing a plasma reactor. Perspective view showing plasma panel laminate, clamp, power supply terminal and mat. Top view showing plasma panel laminate, clamp and power supply terminal. The perspective view which shows the plasma panel laminate, the clamp and the power supply terminal. The side view which shows the plasma panel laminated body. The perspective view which shows the electrode panel. The plan view which shows the electrode panel. The figure for demonstrating the adhesion state of PM (cross-sectional view taken along line BB of FIG. 11). The figure for demonstrating the adhesion state of PM (the cross-sectional view taken along line AA of FIG. 10). In another embodiment, a plan view showing a plasma reactor. In another embodiment, a plan view showing a plasma panel laminate, a clamp, and a power supply terminal. In another embodiment, a perspective view showing a plasma reactor.

Hereinafter, an embodiment embodying the plasma reactor 1 of the present invention will be described in detail with reference to the drawings.

As shown in FIGS. 1 to 3, the plasma reactor 1 of the present embodiment is a device for removing PM contained in the exhaust gas of an automobile engine (not shown), and is attached to an exhaust pipe 2. .. The plasma reactor 1 includes a power supply 3, a case 10, and a plasma panel laminate 20.

The case 10 is formed in a rectangular cylinder shape using, for example, stainless steel. The first cone portion 11 is connected to the first end portion (left end portion in FIG. 1) of the case 10, and the second cone portion 12 is connected to the second end portion (right end portion in FIG. 1) of the case 10. There is. Further, the first cone portion 11 is connected to the upstream side portion 4 (engine side portion) of the exhaust pipe 2, and the second cone portion 12 is connected to the downstream side portion 5 of the exhaust pipe 2 (on the side opposite to the engine side). Part) is connected. The exhaust gas from the engine flows into the case 10 from the upstream portion 4 of the exhaust pipe 2 through the first cone portion 11, passes through the case 10, and then passes through the second cone portion 12. It flows out to the downstream portion 5 of 2.

As shown in FIGS. 1, 4 to 7, the plasma panel laminate 20 is housed in the case 10, and has an upstream end surface 21 into which the exhaust gas flows in and a downstream end surface 22 in which the exhaust gas flows out. It has a substantially rectangular parallelepiped shape with four gas non-passing surfaces 23, 24, 25, and 26. The upstream end surface 21 and the downstream end surface 22 are located on opposite sides of each other in the plasma panel laminated body 20. The gas non-passing surfaces 23 to 26 are located between the upstream end surface 21 and the downstream end surface 22.

Further, the plasma panel laminated body 20 has a structure in which a plurality of electrode panels 30 are laminated. Each electrode panel 30 is arranged in parallel with the passage direction F1 (direction from the first cone portion 11 to the second cone portion 12) of the exhaust gas flowing from the upstream end surface 21 side to the downstream end surface 22 side, and has a gap between them. (In this embodiment, it is arranged so as to have a gap of 0.5 mm). More specifically, the plasma panel laminate 20 has a gas flow path 27 (see FIG. 1) through which exhaust gas passes between adjacent electrode panels 30. The gas flow path 27 includes an opening 28 that opens at the upstream end surface 21 and the downstream end surface 22. The plasma panel laminated body 20 of the present embodiment is a horizontally placed laminated body in which the opening 28 is horizontally long (see FIGS. 4 and 6).

As shown in FIGS. 3, 5, 7, and 9, a virtual surface is located at a position where the distance from the upstream end surface 21 and the distance from the downstream end surface 22 are equal in the plasma panel laminated body 20. C1 is set. The virtual surface C1 is parallel to the stacking direction of the electrode panels 30 and is arranged perpendicular to the exhaust gas passage direction F1. The plasma panel laminate 20 is divided into an upstream region A1 and a downstream region A2 with reference to the virtual surface C1.

Further, as shown in FIGS. 3 and 7, a virtual surface C2 is set at a position where the distance from the gas non-passing surface 23 and the distance from the gas non-passing surface 25 are equal in the plasma panel laminated body 20. ing. The virtual surface C2 is perpendicular to the stacking direction of the electrode panels 30 and is arranged parallel to the exhaust gas passage direction F1. The plasma panel laminated body 20 is divided into an upper half region B1 and a lower half region B2 with reference to the virtual surface C2. Here, the "region B1 of the upper half of the plasma panel laminate 20" means a region that becomes the upper half in the vertical direction when the plasma reactor 1 is attached to the vehicle. Similarly, the “region B2 of the lower half of the plasma panel laminate 20” refers to a region that becomes the lower half in the vertical direction when the plasma reactor 1 is attached to the vehicle.

As shown in FIG. 1, the first wiring 6 and the second wiring 7 are alternately electrically connected to each electrode panel 30 along the thickness direction of the plasma panel laminate 20. The first wiring 6 is electrically connected to the first terminal of the power supply 3, and the second wiring 7 is electrically connected to the second terminal of the power supply 3.

As shown in FIGS. 1, 8 and 9, the electrode panel 30 of the present embodiment has a first main surface 31 and a second main surface 32, and forms a substantially rectangular plate shape having a length of 100 mm and a width of 200 mm. is doing. Further, the electrode panel 30 has a structure in which a discharge electrode 34 (thickness 10 μm) is built in a rectangular plate-shaped dielectric 33. In the present embodiment, the dielectric 33 is made of ceramic such as alumina (Al ₂ O ₃ ), and the discharge electrode 34 is made of tungsten (W). Further, the dielectric 33 has a recess 35 opened at the second main surface 32. The recess 35 extends laterally to the electrode panel 30 and opens at both end faces of the electrode panel 30. In the plasma panel laminate 20 of the present embodiment, the above-mentioned gas flow path 27 is configured between the inner side surface of the recess 35 and the first main surface 31 of the electrode panel 30 adjacent to the lower layer side. Since the electrode panel 30 in the lowermost layer constituting the plasma panel laminated body 20 does not have the electrode panel 30 on the lower layer side, the recess 35 is not formed.

As shown in FIGS. 8 and 9, one side portion (specifically, the portion on the gas non-passing surface 24 side) of the recess 35 in the electrode panel 30 has a first main surface 31 side and a second main surface 32. A pair of conduction structures 41 and 42 for conducting the side are provided. One conducting structure 41 is located on the virtual surface C1, and the other conducting structure 42 is located on the downstream side (downstream side region A2) of the virtual surface C1. Each of the conduction structures 41 and 42 includes a through-hole conductor 43, a first pad 44, and a second pad 45. The through-hole conductor 43 penetrates the electrode panel 30 in the thickness direction. The through-hole conductor 43 provided in one of the conduction structures 41 penetrates the extending portion 36 extending from the discharge electrode 34 to the outer peripheral side. Further, the first pad 44 is formed on the first main surface 31 and is electrically connected to the end portion of the through-hole conductor 43 on the first main surface 31 side. On the other hand, the second pad 45 is formed on the second main surface 32 and is electrically connected to the end of the through-hole conductor 43 on the second main surface 32 side. The first pad 44 and the second pad 45 each have a rectangular shape, and the surfaces thereof are plated with Ni or the like.

As shown in FIGS. 4 to 7, the plasma reactor 1 includes three first clamps 50, 51, 52 for sandwiching and fixing each electrode panel 30 (plasma panel laminate 20) from the gas non-passing surface 24 side. , Each of the electrode panels 30 is provided with three second clamps 53, 54, 55 for sandwiching and fixing each electrode panel 30 from the gas non-passing surface 26 side. Each clamp 50 to 55 is configured so as not to be exposed to the gas flow path 27. Each clamp 50 to 55 is formed by bending a metal plate (for example, a stainless steel plate made of a material such as SUS430). Further, the first clamps 50 to 52 are arranged at equal intervals along the exhaust gas passing direction F1 on the gas non-passing surface 24, and the second clamps 53 to 55 are arranged on the gas non-passing surface 26 of the exhaust gas. They are arranged at equal intervals along the passing direction F1.

The first clamp 50 and the second clamps 53 to 55 arranged on the upstream side of the gas non-passing surface 24 of the first clamps 50 to 52 have only the function of sandwiching each electrode panel 30 in the stacking direction. Have. On the other hand, among the first clamps 50 to 52, the first clamps 51 and 52 arranged in the central portion and the downstream portion of the gas non-passing surface 24 have a function of sandwiching each electrode panel 30 in the stacking direction and a discharge electrode. It has a function as a pair of electrically conducting portions electrically connected to 34. Here, the center line L1 of the first clamp 51, specifically, the first clamp 51 (that is, the distance from the upstream end edge 58 and the distance from the downstream end edge 59 in the first clamp 51 are equal to each other. The line) is located on the virtual surface C1. Further, the distance from the upstream end edge 58 and the distance from the downstream end edge 59 in the first clamp 52, specifically, the center line L2 of the first clamp 52 (that is, in the first clamp 52 are equal to each other). The line set at the position) is located on the downstream side (downstream side region A2) of the virtual surface C1. Therefore, the intermediate point P1 (see FIGS. 3 and 7) between the center line L1 of the first clamp 51 and the center line L2 of the first clamp 52 is located downstream of the virtual surface C1.

Further, as shown in FIGS. 4 to 7, each clamp 50 to 55 includes a clamp main body 56 and a holding plate 57. The clamp body 56 extends in the stacking direction of the electrode panels 30. The pressing plate 57 is integrally formed with the clamp main body 56, and is arranged at both ends of the clamp main body 56. Each holding plate 57 is a leaf spring having elasticity and having a folded structure. Each holding plate 57 is in pressure contact with the gas non-passing surface 23 and the gas non-passing surface 25 of the plasma panel laminated body 20, respectively. The double pressing plates 57 constituting the first clamps 51 and 52 have a first pad 44 formed on the gas non-passing surface 23 (the first main surface 31 of the uppermost electrode panel 30) and a gas non-passing surface. It is in pressure contact with a second pad 45 formed on 25 (the second main surface 32 of the lowermost electrode panel 30).

As shown in FIGS. 2 to 7, the plasma reactor 1 includes a pair of power supply terminals 61 and 62. The power supply terminals 61 and 62 of this embodiment have the same structure as the spark plug. More specifically, the power supply terminals 61 and 62 include an external connection portion, a conductive seal containing metal powder, an insulator, a main metal fitting, talc, packings and the like. The external connection portion is connected to the central shaft 63 via a conductive seal. The tip of the central shaft 63 is arranged in an insulating body. The power supply terminal is not limited to that of the present embodiment, and may have another structure as long as the structure is such that the external connection portion and the case 10 are insulated by an insulator. ..

The tip of the power supply terminal 61 is exposed from the case 10, and the base end (central axis 63) is the center line L1 in the region of the upper half of the first clamp 51 (specifically, the clamp body 56). It is an electric take-out part that is electrically connected to the above). Therefore, the power supply terminal 61 is arranged in the region B1 of the upper half of the plasma panel laminated body 20. Similarly, the tip of the power supply terminal 62 is exposed from the case 10, and the proximal end (central axis 63) is the center line in the region of the upper half of the first clamp 52 (specifically, the clamp body 56). It is an electric take-out unit that is electrically connected to (on L2). Therefore, the power supply terminal 62 is also arranged in the upper half region B1. The power supply terminals 61 and 62 project in the same direction from each other. In this embodiment, the tip of the power supply terminal 61 is connected to the first wiring 6 (see FIG. 1), and the tip of the power supply terminal 62 is connected to the second wiring 7 (see FIG. 1). It is designed to be connected.

As shown in FIGS. 2 to 7, the power supply terminals 61 and 62 are arranged on the same gas non-passing surface 24 along the exhaust gas passing direction F1. Further, the central axis 63 of the power supply terminal 61 is located on the virtual surface C1, and the central axis 63 of the power supply terminal 62 is located on the downstream side (downstream side region A2) of the virtual surface C1. The distance between the central shafts 63 of the pair of power supply terminals 61 and 62 is preferably at least 16 mm or more (50 mm in this embodiment). Further, the separation distance may be increased (for example, 63 mm or more) depending on the adhesion state (dirt degree) of PM in the exhaust gas to the power supply terminals 61 and 62.

As shown in FIGS. 1 and 4, a mat 71 forming a rectangular annular shape in a side view is interposed between the case 10 and the plasma panel laminate 20. The mat 71 has a function of fixing the plasma panel laminate 20 to the case 10. Further, the mat 71 covers the outer surface of the plasma panel laminate 20. More specifically, the mat 71 includes a substantially rectangular plate-shaped first mat piece 72 that covers the gas non-passing surface 23, a substantially rectangular plate-shaped second mat piece 73 that covers the gas non-passing surface 24, and a gas non-passing surface. It is composed of a substantially rectangular plate-shaped third mat piece 74 that covers 25 and a substantially rectangular plate-shaped fourth mat piece 75 that covers the gas non-passing surface 26. The mat 71 is configured by joining the mat pieces 72 to 75 to each other using an adhesive tape or the like, if necessary. Here, as the material constituting the mat 71, for example, an insulating material such as a ceramic fiber, a metal fiber, or a foamed metal can be used.

Further, as shown in FIG. 4, the mat 71 of the present embodiment is formed with two notches 81 and 82 penetrating the mat 71 in the thickness direction. The first clamp 51 is located in the inner region of the notch 81, and the first clamp 52 is located in the inner region of the notch 82. More specifically, the cutouts 81 and 82 include a groove 83 penetrating the second mat piece 73 in the thickness direction and a pair of recesses 84 penetrating the mat pieces 72 and 74 in the thickness direction, respectively. The groove portion 83 extends along the stacking direction of the electrode panel 30, and divides the second mat piece 73. On the other hand, the recess 84 is formed only in a part of the outer peripheral portion of the mat pieces 72 and 74 so as not to divide the mat pieces 72 and 74. The clamp main body 56 of the first clamps 51 and 52 and the central shaft 63 of the power supply terminals 61 and 62 are arranged in the groove 83, and the holding plate 57 of the first clamps 51 and 52 is arranged in the recess 84. Is placed.

Then, as shown in FIG. 4, in the plasma reactor 1 of the present embodiment, between the mat 71 and the first clamps 51 and 52 (specifically, the inner wall surface of the groove 83 and the side edge of the clamp body 56). And between the inner surface of the recess 84 and the outer peripheral edge of the holding plate 57), a gap S1 is provided. The size of the gap S1 is set to 2 mm or more and 30 mm or less (in this embodiment, the minimum is 5 mm). If the size of the gap S1 is less than 2 mm, creeping discharge is likely to occur, so that the first clamps 51 and 52 and the case 10 may conduct with each other via the mat 71. On the other hand, when the gap S1 is larger than 30 mm, the area where the mat 71 can be arranged becomes small. As a result, the contact area between the case 10 and the mat 71 and the contact area between the mat 71 and the plasma panel laminate 20 become small, so that the plasma panel laminate 20 cannot be reliably fixed to the case 10 via the mat 71. there is a possibility. The distance between the mat 71 and the first clamps 51 and 52 changes according to the level of the voltage required for forming the plasma. Generally, it is known that in order to prevent the occurrence of creeping discharge, the distance may be 1 mm per 1 kV. Therefore, the distance between the mat 71 and the first clamps 51 and 52 may be set according to the voltage applied between the electrode panels 30.

As shown in FIG. 1, the plasma reactor 1 of the present embodiment is used, for example, to remove PM contained in the exhaust gas. In this case, when a pulse voltage (for example, peak voltage: 5 kV (5000 V), pulse repetition frequency: 100 Hz) is applied between the power source 3 and the electrode panels 30 adjacent to each other, a dielectric barrier discharge occurs and between the discharge electrodes 34. Plasma is generated by the dielectric barrier discharge. Then, due to the generation of plasma, PM contained in the exhaust gas flowing through the gas flow path 27 is oxidized (combusted) and removed.

Next, a method for manufacturing the plasma reactor 1 will be described.

First, a first to third ceramic green sheet to be a dielectric 33 is formed by using a ceramic material containing alumina powder as a main component. As a method for forming the ceramic green sheet, a well-known molding method such as tape molding or extrusion molding can be used. Then, laser processing is performed on each ceramic green sheet to form a through hole for the through-hole conductor 43. The through hole may be formed by punching, drilling, or the like.

Next, using a conventionally known paste printing device (not shown), the through hole for the through-hole conductor 43 is filled with a conductive paste (tungsten paste in this embodiment), and the through-hole conductor 43 is not fired. Form a through-hole conductor portion of.

Next, the first ceramic green sheet is placed on a support base (not shown). Further, a paste printing apparatus is used to print the conductive paste on the back surface of the first ceramic green sheet. As a result, an unfired electrode having a thickness of 10 μm, which serves as a discharge electrode 34, is formed on the back surface of the first ceramic green sheet. As a printing method of the unfired electrode on the first ceramic green sheet, a well-known printing method such as screen printing can be used.

Then, after the conductive paste is dried, the second ceramic green sheet and the third ceramic green sheet are laminated in order on the back surface of the first ceramic green sheet on which the unfired electrode is printed, and the second ceramic green sheet and the third ceramic green sheet are laminated in order in the sheet laminating direction. Apply pressing force. As a result, each ceramic green sheet is integrated to form a ceramic laminate. Further, using a paste printing apparatus, the conductive paste is printed on the main surface of the first ceramic green sheet to form the unfired first pad 44, and the conductive paste is formed on the back surface of the third ceramic green sheet. The sex paste is printed to form the unbaked second pad 45. The third ceramic green sheet is laminated after being punched according to the shape of the recess 35.

Next, after performing a drying step, a degreasing step, and the like according to a well-known method, the ceramic green sheet and the unfired electrode are heated to a predetermined temperature (for example, about 1400 ° C to 1600 ° C) at which alumina and tungsten can be sintered. Perform simultaneous firing. As a result, the alumina in the first to third ceramic green sheets and the tungsten in the conductive paste are simultaneously sintered, and the dielectric 33, the discharge electrode 34, the through-hole conductor 43, the first pad 44 and the second pad are second. The pad 45 is formed by simultaneous firing, and the first to third ceramic green sheets form the electrode panel 30.

After that, a laminating step is performed, and a plurality of the obtained electrode panels 30 are laminated to form a plasma panel laminated body 20. Next, the plurality of electrode panels 30 are sandwiched and fixed in the stacking direction by using the clamps 50 to 55. At this time, the pair of pressing plates 57 constituting the first clamps 51 and 52 are in pressure contact with the first pad 44 and the second pad 45. Further, by performing welding or the like, the central shaft 63 of the power supply terminal 61 is electrically connected to the upper half region of the clamp body 56 constituting the first clamp 51, and the clamp body constituting the first clamp 52 is formed. The central shaft 63 of the power supply terminal 62 is electrically connected to the area of the upper half of 56. Next, the mat 71 is attached so as to cover the outer surface of the plasma panel laminate 20, and then the case 10 is attached so as to cover the outer surface of the mat 71. After that, the first wiring 6 is connected to the tip of the power supply terminal 61, and the second wiring 7 is connected to the tip of the power supply terminal 62. Through the above process, the plasma reactor 1 is completed.

Therefore, according to this embodiment, the following effects can be obtained.

(1) In the plasma reactor 1 of the present embodiment, the intermediate point P1 of the first clamps 51 and 52 is located on the downstream side of the virtual surface C1. Therefore, when the exhaust gas flows into the plasma reactor 1, it becomes difficult for PM and water in the exhaust gas to reach the first clamps 51 and 52, so that PM8 and water are prevented from adhering to the first clamps 51 and 52. (See FIGS. 10 and 11). Further, since the first clamps 51 and 52 are arranged at a position away from the upstream side of the plasma reactor 1 where PM8 is likely to be deposited, the deposited PM8 is prevented from adhering to the first clamps 51 and 52. Become so. As a result, conduction between the first clamps 51 and 52 via PM8 and water and conduction between the first clamps 51 and 52 and the case 10 via PM8 and water are prevented, so that the first clamp 51, It is possible to secure the insulation between the 52 and the insulation between the first clamps 51 and 52 and the case 10. Therefore, the reliability of the plasma reactor 1 can be improved.

(2) In the present embodiment, the gap S1 is formed between the mat 71 and the first clamps 51 and 52 by forming the notches 81 and 82 with respect to the mat 71 so as to avoid the first clamps 51 and 52. It is provided. Therefore, the number of parts of the plasma reactor 1 can be reduced as compared with the case where a gap is provided between the mat and the clamp, for example, by arranging the clamp between the plurality of mats.

(3) The plasma reactor 1 of the present embodiment is attached to the exhaust pipe 2 via the first cone portion 11 and the second cone portion 12. As a result, the resistance in the exhaust gas flow path through which the exhaust gas flows in the order of the upstream portion 4 of the exhaust pipe 2 → the first cone portion 11 → the plasma reactor 1 → the second cone portion 12 → the downstream portion 5 of the exhaust pipe 2 is reduced. Therefore, the pressure loss in the exhaust gas flow path can be suppressed. As a result, it is possible to prevent a decrease in engine output due to pressure loss.

The above embodiment may be changed as follows.

In the plasma reactor 1 of the above embodiment, the center line L1 of the first clamp 51 is located on the virtual surface C1, and the center line L2 of the first clamp 52 is located downstream of the virtual surface C1. However, both the center line L1 of the first clamp 51 and the center line L2 of the first clamp 52 may be located on the downstream side of the virtual surface C1. Further, if the intermediate point P1 between the center line L1 and the center line L2 is located on the downstream side of the virtual surface C1, the center line L1 of the first clamp 51 on the upstream side is located on the upstream side of the virtual surface C1. You may be doing it.

In the plasma reactor 1 of the above embodiment, the first clamps 51 and 52, which are electrical conduction portions, and the power supply terminals 61, 62, which are electrical extraction portions, are on the same side (gas non-passing surface 24) in the plasma panel laminate 20. It was placed in) above. However, the electric conduction part and the electric take-out part may be arranged at different positions in the plasma panel laminated body. For example, as shown in the plasma reactor 91 of FIGS. 12 and 13, the clamps 92 and 93 (electrical conduction section) and the power supply terminals 94 and 95 (electrical extraction section) are opposite to each other with the plasma panel laminate 96 interposed therebetween. It may be located on the side. Specifically, the clamp 92 and the power supply terminal 94 may be arranged on the gas non-passing surface 97, and the clamp 93 and the power supply terminal 95 may be arranged on the gas non-passing surface 98. The clamps 92 and 93 are located on the downstream side of the virtual surface C3. Further, since the intermediate point of the pair of clamps 92 and 93 is at the same position as the clamps 92 and 93, it is located on the downstream side of the virtual surface C3.

In the plasma reactor 1 of the above embodiment, the pair of power supply terminals 61 and 62 project in the same direction (sideways) from the gas non-passing surface 24 (side surface), but the power supply terminals are oriented in different directions. It may be a protruding one. For example, as shown in the plasma reactor 101 of FIG. 14, the pair of power supply terminals 102, 103 (electricity extraction unit) may protrude in the same direction (vertical direction) from the gas non-passing surface 23 (upper surface). .. In this case, the plasma panel laminated body housed in the case 104 is a vertically placed laminated body in which the opening 28 (see FIGS. 4 and 6) is vertically long. Further, the clamp serving as the electrical conduction portion sandwiches and fixes the plasma panel laminate from the gas non-passing surface 23 (upper surface) side. That is, the clamp is placed in the upper half region of the plasma panel laminate. The clamp may be arranged in the lower half region of the plasma panel laminate.

-In the above embodiment, the power supply terminals 61 and 62 are arranged in the region B1 of the upper half of the plasma panel laminate 20. However, the power supply terminals 61 and 62 may be arranged on the virtual surface C2 or may be arranged in the region B2 of the lower half of the plasma panel laminate 20.

In the plasma reactor 1 of the above embodiment, the gap S1 is provided between the inner side surface of the notches 81 and 82 and the outer peripheral edge of the first clamps 51 and 52, but the gap S1 is omitted and the notch 81 is omitted. , 82 may be in contact with each other and the outer peripheral edges of the first clamps 51 and 52 may be brought into contact with each other.

The mat 71 of the above embodiment was configured by joining the first to fourth mat pieces 72 to 75 to each other. However, the mat may have an undivided structure.

The electrode panel 30 of the above embodiment is configured by incorporating the discharge electrode 34 in the dielectric 33. However, the electrode panel may be formed by forming the discharge electrode 34 on the surface of the dielectric 33.

-The plasma reactor 1 of the above embodiment has been used for purifying exhaust gas of an automobile engine, but may be used for purifying exhaust gas of a ship or the like, for example. Further, the plasma reactor 1 may be any one that performs plasma treatment, and may not be one that treats exhaust gas, or may not be used for purification.

Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments are listed below.

(1) In the means 1, the pair of electrical conduction portions are arranged closer to the end surface on the downstream side than the virtual surface.

(2) The means 1 is characterized in that it has an electric take-out part that is electrically connected to the electric conductive part, and the electric take-out part is arranged closer to the downstream end surface than the virtual surface. Plasma reactor.

(3) In the means 1, a gas flow path through which gas passes from the upstream end face side to the downstream end face side is provided between the adjacent electrode panels, and the pair of electrically conducting portions allows gas to pass through. A plasma reactor characterized by being arranged along the direction.

(4) In the technical idea (3), the electric conduction part is electrically connected to the electric conduction part, and the electric take-out part is arranged in a pair along the gas passage direction, and is a pair. A plasma reactor characterized in that the distance between the electric extraction portions is 16 mm or more, preferably 63 mm or more.

(5) In the means 1, the pair of electrically conducting portions are located on opposite sides of each other with the plasma panel laminate interposed therebetween.

(6) In the means 1, the electrode panel has a first main surface and a second main surface, and the electrode panel is made conductive between the first main surface side and the second main surface side. A plasma reactor provided with a conduction structure, wherein the conduction structure is located downstream of the virtual surface.

1,91,101 ... Plasma reactors 10,104 ... Cases 20,96 ... Plasma panel laminate 21 ... Upstream side end face 22 ... Downstream side end face 27 ... Gas flow path 30 ... Electrode panel 34 ... Discharge electrodes 51, 52 ... Electrical conduction First clamp 61, 62, 94, 95, 102, 103 as a part ... Power supply terminal 71 as an electric take-out part 71 ... Mat 81, 82 ... Notch 92, 93 ... Clamp B1 as an electric conduction part ... Plasma panel lamination Areas C1 and C3 in the upper half of the body ... Virtual surface P1 ... Midpoint between a pair of electrically conductive parts

Claims (5)

It has an upstream end face where gas flows in and a downstream end face where gas flows out, and has a structure in which a plurality of electrode panels having discharge electrodes are laminated, and plasma is applied when a voltage is applied between the adjacent electrode panels. With a plasma panel laminate that generates
A plasma reactor including a pair of electrically conducting portions electrically connected to the discharge electrodes of the plurality of electrode panels.
The electrically conductive portion is a clamp having a function of sandwiching the plurality of electrode panels in the stacking direction.
It has a case in which the plasma panel laminate is housed, and a mat interposed between the case and the plasma panel laminate to fix the plasma panel laminate to the case.
When the virtual surface is set at a position where the distance from the upstream end surface and the distance from the downstream end surface are equal in the plasma panel laminate, the pair of electrically conducting portions are located downstream of the virtual surface. The midpoint is located,
A plasma reactor characterized in that a notch portion penetrating the mat in the thickness direction is arranged on the mat, and the electrically conductive portion is located in an inner region of the notch portion. The plasma reactor according to claim 1, wherein the plasma reactor has an electric take-out unit electrically connected to the electric conduction part, and the electric take-out part is located on the downstream side of the virtual surface. A gas flow path through which gas passes from the upstream end face side to the downstream end face side is provided between the adjacent electrode panels.
The plasma reactor according to claim 1 or 2, wherein the electrically conducting portion is configured so as not to be exposed to the gas flow path. It has an upstream end face where gas flows in and a downstream end face where gas flows out, and has a structure in which a plurality of electrode panels having discharge electrodes are laminated, and plasma is applied when a voltage is applied between the adjacent electrode panels. With a plasma panel laminate that generates
A plasma reactor including a pair of electrically conducting portions electrically connected to the discharge electrodes of the plurality of electrode panels.
The electrically conductive portion is a clamp having a function of sandwiching the plurality of electrode panels in the stacking direction.
When the virtual surface is set at a position where the distance from the upstream end surface and the distance from the downstream end surface are equal in the plasma panel laminate, the pair of electrically conducting portions are located downstream of the virtual surface. The midpoint is located,
A plasma reactor having an electric take-out part electrically connected to the electric conduction part, wherein the electric take-out part is arranged only in the upper half region of the plasma panel laminate. It has an upstream end face where gas flows in and a downstream end face where gas flows out, and has a structure in which a plurality of electrode panels having discharge electrodes are laminated, and plasma is applied when a voltage is applied between the adjacent electrode panels. With a plasma panel laminate that generates
A plasma reactor including a pair of electrically conducting portions electrically connected to the discharge electrodes of the plurality of electrode panels.
The electrically conductive portion is a clamp having a function of sandwiching the plurality of electrode panels in the stacking direction.
When the virtual surface is set at a position where the distance from the upstream end surface and the distance from the downstream end surface are equal in the plasma panel laminate, the pair of electrically conducting portions are located downstream of the virtual surface. The midpoint is located,
A plasma reactor characterized in that the pair of electrically conducting portions are arranged only in the upper half region of the plasma panel laminate.

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