JP6917813B2 - Plasma reactor, air purifier - Google Patents

Description

The present invention relates to a plasma reactor for purifying air and an air purifier using the same.

In warehouses for storing crops and containers for transporting crops, if the storage period or transportation period is long, the bacteria attached to the crops may propagate and the crops may spoil. Then, if the propagated bacteria spread in the warehouse or the container, the damage to the crops will be further increased. Also, for example, when transporting fruits and vegetables such as apples in a container, if the shipment amount of apples is not enough to fill the container, other fruits and vegetables (persimmons, citrus fruits, etc.) may be loaded in the container together with the apples. many. However, in this case, there is a problem that ethylene generated from apples causes other fruits and vegetables to spoil. Therefore, conventionally, it has been considered to perform various treatments such as sterilization of bacteria, inactivation of viruses, and decomposition of ethylene by using a plasma reactor (see, for example, Patent Documents 1 and 2).

For example, Patent Document 1 discloses that by generating plasma between adjacent electrode panels, the air flowing between the electrode panels is purified (sterilization of bacteria, inactivation of viruses, decomposition of ethylene, etc.). Has been done. Further, Patent Document 2 discloses a technique of burying a first electrode and a second electrode surrounding a through hole in a ceramic substrate and generating plasma between the two electrodes to purify the air passing through the through hole. Has been done.

Japanese Patent No. 49265653 (Fig. 3, etc.) WO2013 / 031800 (Fig. 3 etc.)

By the way, when installing an air purifier in a warehouse or a container, the installation space is limited, so that the air purifier is required to be miniaturized. In addition, when installing an air purifier in a container, a battery is required as a power source for the air purifier, but if the container is transported for a long period of time, the battery will be consumed, which saves power in the air purifier. Desired.

However, the technique described in Patent Document 1 has a problem that the component cost and the assembly cost of the plasma reactor are high because a plurality of electrode panels need to be laminated because of the structure. Further, since the plasma reactor of Patent Document 1 has a structure in which a plurality of electrode panels are laminated, the capacitance tends to be large. Therefore, in order to drive the plasma reactor, a large amount of electric power must be applied, which causes a problem that it is difficult to save electric power. It is also conceivable to reduce the power consumption by driving the plasma reactor using a pulse power supply and lowering the pulse application frequency of the pulse power supply to, for example, about 100 Hz. However, in this case, since the pulse application frequency is lowered to within the audible range, there is a problem that the noise generated when the plasma reactor is driven becomes large.

Further, the prior art described in Patent Document 2 has a structure in which plasma is generated along the inner surface of the through hole provided in the ceramic substrate. Therefore, if the inner diameter of the through hole is increased in order to reduce the pressure loss when the air passes through the through hole, the plasma does not reach the central portion of the through hole, and there is a problem that the air cannot be reliably purified.

The present invention has been made in view of the above problems, and an object of the present invention is to use a plasma reactor capable of reliably purifying air, suppressing power consumption, and reducing manufacturing costs. It is to provide the air purifier that was there.

As means (means 1) for solving the above-mentioned problems, a dielectric substrate having a pair of main surfaces and having a penetrating portion penetrating the pair of main surfaces is formed, and a first electrode formed on the substrate. In a plasma reactor including one discharge electrode and a second discharge electrode formed on the substrate and having a polarity different from that of the first discharge electrode, the first discharge electrode and the second discharge electrode are perpendicular to the main surface. It is a layered electrode that is arranged so as to sandwich the penetrating portion when viewed from a different direction and extends in the surface direction of the main surface, and the first discharge electrode and the second discharge across the penetrating portion. There is a plasma reactor characterized in that plasma is generated by a discharge generated between electrodes.

Therefore, in the invention described in the above means 1, a plurality of substrates are formed because the first discharge electrode and the second discharge electrode that generate plasma and the penetrating portion through which the air purified by plasma passes are formed on the same substrate. The plasma reactor can be constructed without using. Therefore, the manufacturing cost of the plasma reactor can be reduced. Further, the capacitance of the plasma reactor is smaller than that in the case where the plasma reactor is composed of a plurality of substrates. As a result, it is not necessary to apply a large amount of electric power when driving the plasma reactor, so that the power consumption can be suppressed. Further, in the invention described in the means 1, plasma is generated by the electric discharge across the penetrating portion, so that the plasma reaches the entire penetrating portion. As a result, the air passing through the penetrating portion can be reliably purified.

The plasma reactor includes a dielectric substrate, a first discharge electrode formed on the substrate, and a second discharge electrode formed on the substrate and having a polarity different from that of the first discharge electrode. Here, examples of the materials for forming the first discharge electrode and the second discharge electrode include tungsten (W), molybdenum (Mo), ruthenium oxide (RuO ₂ ), silver (Ag), copper (Cu), and platinum (Pt). ) And so on. Examples of the material for forming the dielectric include ceramics such as glass (SiO ₂ ), alumina (Al ₂ O ₃ ), aluminum nitride (AlN), yttrium oxide (Y ₂ O ₃ ), and mixtures thereof. Can be done. If the material of the first discharge electrode and the second discharge electrode is tungsten and the material of the dielectric is alumina, the firing temperature is lower than that of aluminum nitride or the like, so that the plasma reactor can be formed easily and inexpensively. Can be done.

Further, it is preferable that at least one of the first discharge electrode and the second discharge electrode is in an unexposed state on the inner wall surface of the penetrating portion. If the first discharge electrode and the second discharge electrode are exposed on the inner wall surface of the through hole, there is a risk that the discharge electrodes will be consumed by the discharge.

Further, first and second discharge electrodes are Ru electrode der layered extending in the plane direction of the main surface of the substrate. In this case , since the first discharge electrode and the second discharge electrode can be arranged so as to extend along the outer peripheral portion of the through hole, the discharge across the through portion can be performed over a wide range. Further, the first discharge electrode and the second discharge electrode are preferably layered electrodes embedded inside the substrate. If the first discharge electrode and the second discharge electrode are exposed to the outside of the substrate, there is a risk that the discharge electrodes will be consumed by the discharge. The first discharge electrode and the second discharge electrode are preferably layered electrodes embedded at the same depth inside the substrate. By doing so, the first discharge electrode and the second discharge electrode can be formed at the same time in the same step, so that the plasma reactor can be easily formed.

The first and second discharge electrodes is an electrode layered provided on the principal surface together when extending in the plane direction of the main surface of the substrate, and covered by a protective layer made of a dielectric material May be good. In this case, the first discharge electrode and the second discharge electrode are exposed to the outside of the substrate. However, since the first discharge electrode and the second discharge electrode are coated with a protective layer, it is possible to prevent the discharge electrodes from being consumed due to discharge. Further, the first discharge electrode and the second discharge electrode are not embedded inside the substrate but are located outside the substrate. Moreover, since the first discharge electrode and the second discharge electrode are provided on the same main surface, the first discharge electrode and the second discharge electrode can be formed at the same time in the same step. Therefore, the first discharge electrode and the second discharge electrode, and thus the plasma reactor can be easily formed.

Further, the substrate is formed with penetrating portions penetrating the pair of main surfaces. Here, as the shape of the penetrating portion in a plan view, for example, a circular shape in a plan view, an elliptical shape in a plan view, a rectangular shape in a plan view, a triangular shape in a plan view, and the like can be mentioned. The penetrating portion is a groove-shaped penetrating portion, and it is preferable that the first discharge electrode and the second discharge electrode are arranged so as to extend along the length direction of the groove-shaped penetrating portion. By doing so, since the opening area of the penetrating portion is increased, the pressure loss when the air passes through the penetrating portion can be reduced. Further, since the first discharge electrode and the second discharge electrode are arranged so as to extend along the length direction of the penetrating portion, the discharge across the penetrating portion can be performed over a wider range. Further, when the penetrating portion is a groove-shaped penetrating portion, a plurality of groove-shaped penetrating portions are arranged in parallel, and the first discharge electrode and the second discharge electrode are alternately arranged along the width direction of the groove-shaped penetrating portion. It is preferably arranged in. In this way, the amount of plasma generated is large, so that the air passing through the penetrating portion can be efficiently purified.

The groove-shaped penetrating portion may have a wide end. In this case, the creepage distance between the adjacent first discharge electrode and the second discharge electrode on the inner wall surface of the penetrating portion becomes long, so that the creepage discharge between the adjacent first discharge electrode and the second discharge electrode is suppressed. can do. Further, a plurality of substrates may be laminated in the substrate thickness direction. In this case, the amount of plasma generated is further increased, so that the air passing through the penetrating portion can be purified more efficiently.

As another means (means 2) for solving the above-mentioned problems, the plasma reactor according to the above-mentioned means 1, a power source for applying a voltage for generating plasma to the plasma reactor, and air are applied to the penetrating portion. There is an air purifier provided with a blowing means for discharging ozone generated in the plasma reactor together with the air while flowing the air.

Therefore, in the invention described in the above means 2, since the first discharge electrode and the second discharge electrode that generate plasma and the penetrating portion through which the air purified by plasma passes are formed on the same substrate, a plurality of substrates. The plasma reactor can be constructed without using. Therefore, the manufacturing cost of the plasma reactor and, by extension, the manufacturing cost of the air purifier can be reduced. Further, the capacitance of the plasma reactor is smaller than that in the case where the plasma reactor is composed of a plurality of substrates. As a result, it is not necessary to apply a large amount of electric power when driving the plasma reactor, so that the power consumption of the plasma reactor and, by extension, the power consumption of the air purifier can be suppressed. Further, in the plasma reactor, the plasma is generated by the electric discharge across the penetrating portion, so that the plasma reaches the entire penetrating portion. As a result, the air passing through the penetrating portion can be reliably purified.

The plasma reactor is preferably driven by using a power source having a center frequency of a voltage waveform of 20 kHz or more. In this case, since the center frequency of the power supply is higher than the audible range, the noise generated when the plasma reactor is driven can be reduced. Further, the power source may be a battery. In this case, the power supply can be miniaturized, so that the power supply can be reliably installed in a warehouse, a container, or the like.

The air blowing means constituting the air purifier has a function of flowing air through the penetrating portion and releasing ozone generated in the plasma reactor together with the air. Here, the type of the blowing means is not particularly limited, and examples thereof include a fan having a rotary blade. Such a fan is suitable for installation in an air purifier because it is relatively small, inexpensive, and power-saving among the ventilation means. Further, as the blowing means, it is also possible to select a means that does not have a member that makes a rotary motion such as a rotary blade, for example, a means that creates a vacuum state in the flow path and allows air to flow in the flow path. .. The position of the blower means is not particularly limited, but for example, the blower means is preferably arranged on the upstream side of the plasma reactor. If the blowing means is arranged on the downstream side of the plasma reactor, ozone generated in the plasma reactor may deteriorate the parts constituting the blowing means.

By the way, if the concentration of ozone generated in the plasma reactor becomes high, ozone may affect workers and the like. Therefore, the above air purifier has an ozone concentration sensor that measures the ozone concentration and a control that reduces the power applied to the plasma reactor from the power supply when the ozone concentration measured by the ozone concentration sensor exceeds the permissible value. It is preferable to provide a control means for performing the above. By doing so, when the concentration of ozone exceeds the permissible value, the electric power applied to the plasma reactor is reduced, so that the amount of ozone generated itself is reduced. Therefore, the ozone concentration can be reliably controlled.

Further, the control means may perform control to reduce the output of the blower means when the ozone concentration measured by the ozone concentration sensor exceeds the permissible value. In this way, by reducing the output of the blower means, the amount of air flowing into the penetrating portion and the amount of ozone released will be reduced. Therefore, the ozone concentration can be controlled more reliably.

A schematic cross-sectional view showing a warehouse in which an air purifier is installed in the first embodiment. Schematic cross-sectional view showing an air purifier. The perspective view which shows the plasma reactor. Front view showing a plasma reactor. FIG. 4 is a cross-sectional view taken along the line AA of FIG. Front view of the main part showing the plasma reactor. FIG. 5 is a cross-sectional view taken along the line BB of FIG. Front view of the main part showing the through hole. The front view of the main part which shows the problem when the width of a through hole is constant. The front view of the main part which shows the 1st ceramic green sheet. The front view of the main part which shows the 2nd ceramic green sheet. The front view of the main part which shows the state which the unfired electrode was printed on the 1st ceramic green sheet. The perspective view which shows the plasma reactor in 2nd Embodiment. FIG. 13 is a cross-sectional view taken along the line CC of FIG. In another embodiment, a front view of a main part showing a plasma reactor. In another embodiment, a partial cross-sectional view showing a plasma reactor. In another embodiment, a schematic cross-sectional view showing a container in which an air purifier is installed.

[First Embodiment]
Hereinafter, a first embodiment embodying the air purifier of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, the air purifier 1 of the present embodiment is an agricultural air purifier installed in a warehouse 2 for storing agricultural products. The air purifier 1 purifies the air A1 taken in from the internal space of the warehouse 2 and supplies the purified air A1 to the internal space again. Further, the device main body 3 constituting the air purifier 1 is installed on the floor portion 8 in the warehouse 2, and the internal area of the device main body 3 is divided into an upper area 4 and a lower area 5 by a partition plate 6. Has been done.

As shown in FIGS. 1 and 2, the air purifier 1 includes a plasma reactor 11, a power supply 12, and a fan 13 (blower means). The plasma reactor 11 is housed in a housing 14 housed in the upper region 4.

The housing 14 is formed in a rectangular tubular shape using, for example, stainless steel (SUS316 in this embodiment). The first end of the housing 14 (the left end in FIGS. 1 and 2) is located on the upstream side, and the second end of the housing 14 (the right end in FIGS. 1 and 2) is located on the downstream side. There is. The air A1 in the warehouse 2 flows into the housing 14 through the first end portion, passes through the housing 14, and then flows out into the warehouse 2 through the second end portion.

As shown in FIGS. 2 to 7, the plasma reactor 11 is driven by a power source 12 (see FIG. 1) and includes a ceramic substrate 20. The ceramic substrate 20 of the present embodiment has a pair of main surfaces (first main surface 21 and second main surface 22) located on opposite sides in the thickness direction, has a side of 95 mm, and has a thickness of 95 mm. It has a substantially rectangular flat plate shape of 1.0 mm. In the ceramic substrate 20, the first main surface 21 faces the upstream side of the housing 14 (left end side in FIG. 2), and the second main surface 22 faces the downstream side of the housing 14 (right end side in FIG. 2). It is designed to stand upright in a standing state.

Then, the ceramic substrate 20 is formed with through holes 31 (penetration portions) that penetrate the first main surface 21 and the second main surface 22 and open at the first main surface 21 and the second main surface 22 at a plurality of locations. Has been done. Each through hole 31 is a groove-shaped through portion having a length of 70 mm or more and 80 mm or less (78 mm in this embodiment). Further, the through holes 31 are arranged at equal intervals along the width direction of the through holes 31 and are arranged in parallel.

As shown in FIGS. 3, 4, 6, and 7, each through hole 31 has a central portion 32 extending along the length direction of the through hole 31 and a pair of end portions (first end portion 33). And the second end 34). The central portion 32 is a rectangular penetrating portion having a length of 70 mm or more and 80 mm or less (74 mm in the present embodiment) and a width of 1 mm or more and 2 mm or less (1 mm in the present embodiment). Further, the first end portion 33 and the second end portion 34 have a length of 1 mm or more and 5 mm or less (2 mm in the present embodiment) and a width of 1 mm or more and 5 mm or less (1.5 mm in the present embodiment). It is a substantially rectangular penetrating part. That is, in the through hole 31 of the present embodiment, the end portions 33 and 34 are formed wider than the central portion 32. The connecting portions of the end portions 33 and 34 with the central portion 32 are formed so as to gradually become narrower as they approach the central portion 32.

As shown in FIGS. 5 and 7, in the ceramic substrate 20, a plurality of first discharge electrodes 41 and a plurality of second discharge electrodes 42 having polarities different from those of the first discharge electrode 41 are made of a rectangular plate-shaped dielectric. It has a structure built into the body 23. In the present embodiment, the material of the first discharge electrode 41 and the second discharge electrode 42 is tungsten (W), and the material of the dielectric 23 is alumina (Al ₂ O ₃ ). Further, each first discharge electrode 41 and each second discharge electrode 42 are arranged between the first and second ceramic insulating layers 24 and 25 constituting the dielectric 23. That is, each of the first discharge electrodes 41 and each second discharge electrode 42 is a layered electrode embedded in the ceramic substrate 20 at the same depth and extending in the plane direction of the substrate.

As shown in FIG. 7, each first discharge electrode 41 and each second discharge electrode 42 are arranged so as to extend along the length direction of each through hole 31. Further, the first discharge electrodes 41 and the second discharge electrodes 42 are alternately arranged along the width direction of the through holes 31. The through holes 31 are arranged so as to be sandwiched between the first discharge electrode 41 and the second discharge electrode 42 in a plan view of the substrate.

More specifically, the proximal end portion of each first discharge electrode 41 is connected to a first connecting portion 43 extending in a direction orthogonal to the first discharge electrode 41. That is, the first discharge electrodes 41 are electrically connected to each other via the first connecting portion 43. The tip of each first discharge electrode 41 is located in the vicinity of the connecting portion between the central portion 32 and the second end portion 34 in the through hole 31. Similarly, the base end portion of each second discharge electrode 42 is connected to a second connecting portion 44 extending in a direction orthogonal to the second discharge electrode 42. That is, the second discharge electrodes 42 are electrically connected to each other via the second connecting portion 44. The tip of each second discharge electrode 42 is located near the connecting portion between the central portion 32 and the first end portion 33. As a result of the above, each through hole 31 is substantially surrounded by the first discharge electrode 41 and the second discharge electrode 42. In other words, the first discharge electrode 41 and the second discharge electrode 42 do not surround the through hole 31 by themselves in the plan view of the substrate.

As shown in FIG. 7, each of the discharge electrodes 41 and 42 has a strip shape of 87 mm in length × 0.4 mm in width × 10 μm in thickness. The distance between the outer peripheral edge of the first discharge electrode 41 and the opening edge of the through hole 31 and the distance between the outer peripheral edge of the second discharge electrode 42 and the opening edge of the through hole 31 are determined from the viewpoint of suppressing power consumption. Speaking of which, it is preferable that it is as small as possible. However, in the present embodiment in which alumina is used as the material of the ceramic (dielectric 23), the withstand voltage is 15 kV / mm. Therefore, when the power supply 12 having a peak voltage of 9 kV is used, the outer peripheral edge of the first discharge electrode 41 is used. It is necessary to secure a distance of 0.6 mm or more between the second discharge electrode 42 and the outer peripheral edge of the second discharge electrode 42. Therefore, the minimum value of the distance between the outer peripheral edge of the first discharge electrode 41 and the opening edge of the through hole 31 and the minimum value of the distance between the outer peripheral edge of the second discharge electrode 42 and the opening edge of the through hole 31 are 0. It is preferably 3 mm or more (0.3 mm in this embodiment). If the minimum value of the above distance is less than 0.3 mm, a discharge penetrating the ceramic may occur and normal discharge may not be possible.

Further, the width of the central portion 32 of the through hole 31 changes according to the level of the voltage required for forming the plasma. Generally, the breakdown voltage of the atmosphere is about 3 kV / mm, and the voltage applied between the discharge electrodes 41 and 42 is less than 10 kV (9 kV in this embodiment). Therefore, in the present embodiment, the width of the central portion 32 is set to 1 mm in order to perform stable discharge.

Further, the creepage distance between the adjacent discharge electrodes 41 and 42 on the inner wall surface of the end portions 33 and 34 of the through hole 31 also changes according to the level of the voltage required for plasma formation. Generally, in order to prevent the occurrence of creeping discharge, the distance may be about 1 mm per 3 kV. Therefore, the creepage distance is preferably a distance corresponding to the voltage (9 kV) applied between the discharge electrodes 41 and 42, and is preferably set to, for example, 3 mm or more. Therefore, in the through hole 31 of the present embodiment, the creepage distance L1 is set to 3 mm or more (3.5 mm in the present embodiment) by forming the end portions 33 and 34 wider than the central portion 32 (in this embodiment). (See FIG. 8). Since the creepage distance L1 is longer than the creepage distance L2 (see FIG. 9) when the width of the through hole 30 is constant (for example, 1 mm), it is possible to more reliably prevent the occurrence of creepage discharge. ..

As shown in FIGS. 3 to 7, on the surface of the first ceramic insulating layer 24 constituting the ceramic substrate 20, a first pad portion 35 for applying a voltage to the first discharge electrode 41 and a first pad portion 35 are provided. A second pad portion 36 for applying a voltage to the two discharge electrodes 42 is formed. The first pad portion 35 is connected to both ends (upper end and lower end) of the first connecting portion 43, and the second pad portion 36 is connected to both ends (upper end and lower end) of the second connecting portion 44, respectively. Further, the first pad portion 35 is arranged at two of the four corners of the ceramic substrate 20 (upper right portion and lower right portion in FIG. 4), and the second pad portion 36 is arranged at two of the four corners of the ceramic substrate 20. (In FIG. 4, the upper left part and the lower left part) are arranged. The first pad portion 35 and the second pad portion 36 each have a rectangular shape in a plan view, and the surfaces thereof are plated with Ni or the like. A first wiring (not shown) is connected to the first pad portion 35 located at the upper right portion of the ceramic substrate 20 by soldering, and to the second pad portion 36 located at the upper left portion of the ceramic substrate 20. , The second wiring (not shown) is connected by soldering. The first wire is electrically connected to the first terminal of the power supply 12, and the second wire is electrically connected to the second terminal of the power supply 12. The first and second wirings may be connected to the pad portions 35 and 36 by bringing the contact pins into contact with the pad portions 35 and 36.

As shown in FIGS. 2 to 4, the plasma reactor 11 of the present embodiment purifies the air A1 passing through the through hole 31 (sterilization of bacteria, inactivation of virus, generation from agricultural products in warehouse 2). It is used for decomposition of ethylene. In this case, when a voltage (for example, peak voltage: 9 kV, center frequency of voltage waveform: 20 kHz) is applied between the adjacent discharge electrodes 41 and 42 from the power supply 12 (AC power supply in this embodiment), the through hole 31 is formed. Bacteria contained in the passing air A1 are electrostatically collected on the ceramic substrate 20. Further, when a voltage is applied between the adjacent discharge electrodes 41 and 42, a dielectric barrier discharge is generated between the discharge electrodes 41 and 42 across the through hole 31, and plasma is generated. Then, the electric shock caused by the dielectric barrier discharge kills the bacteria contained in the air A1 passing through the through hole 31, and inactivates the virus contained in the air A1 also passing through the through hole 31. Further, the plasma decomposes ethylene contained in the air A1 passing through the through hole 31. That is, the ceramic substrate 20 functions as a collecting unit for electrostatically collecting bacteria and viruses contained in the air A1, and sterilizes the bacteria contained in the air A1 and the bacteria electrostatically collected on the ceramic substrate 20. A function as a sterilizing part, a function as an inactivating part for inactivating a virus contained in air A1 and a virus electrostatically collected on a ceramic substrate 20, and a decomposition part for decomposing ethylene contained in air A1. It also functions as a virus.

As shown in FIGS. 1 and 2, the fan 13 is arranged on the upstream side of the plasma reactor 11 in the upper region 4 of the apparatus main body 3, and has a function of sending air A1 to the plasma reactor 11. There is. The fan 13 also has a function of allowing air A1 to flow through the through hole 31. Further, the fan 13 also has a function of discharging ozone generated when the dielectric barrier discharge is performed in the plasma reactor 11 into the warehouse 2 together with the air A1. Ozone is discharged through a duct 7 that opens above the device main body 3.

As shown in FIG. 1, the lower region 5 of the apparatus main body 3 includes an intake port 51 located on the upstream side (left end side in FIG. 1) and an exhaust port 52 located on the downstream side (right end side in FIG. 1). have. A fan 53 that ventilates the inside of the lower region 5 is attached to the exhaust port 52. That is, in the present embodiment, the air A1 is introduced into the lower region 5 from the intake port 51 located on the same side as the first end of the housing 14 in the apparatus main body 3, and the second end of the housing 14 in the apparatus main body 3. Air A1 is discharged to the outside of the lower region 5 from the exhaust port 52 located on the same side as the above.

A linear flow path connecting the intake port 51 and the exhaust port 52 is provided in the lower region 5, and the ozone concentration sensor 54, the power supply 12, and the control device 60 are sequentially arranged on the flow path from the upstream side. Have been placed. The ozone concentration sensor 54 measures the concentration of ozone (ozone concentration) contained in the air A1 introduced into the lower region 5, and outputs an ozone concentration detection signal to the CPU 61 of the control device 60. .. Further, the power supply 12 and the control device 60 are cooled by the fan 13.

Next, the electrical configuration of the air purifier 1 will be described.

As shown in FIG. 1, the air purifier 1 includes a control device 60 for comprehensively controlling the entire equipment. The control device 60 includes a CPU 61 (control means), a ROM 62, a RAM 63, an input / output circuit, and the like. The CPU 61 is electrically connected to the plasma reactor 11, the power supply 12, and the fan 13, and controls them by various drive signals.

Further, the CPU 61 is electrically connected to the operation panel 71 included in the air purifier 1 by wire. The operation panel 71 transmits and receives signals to and from the CPU 61. Further, the operation panel 71 is arranged so as to be separated from the device main body 3 of the air purifier 1. Specifically, the operation panel 71 is arranged outside the warehouse 2 and is attached to the wall portion 72 of the warehouse 2. On the display screen of the operation panel 71, for example, information indicating the ozone concentration in the warehouse 2 is displayed. The operation panel 71 may be connected to the CPU 61 wirelessly (for example, a telephone line, an internet line, etc.). Further, the operation panel 71 may be a portable device such as a personal computer or a smartphone.

Next, a method of purifying the air A1 by the air purifier 1 will be described.

First, the CPU 61 controls to drive the plasma reactor 11, and controls to generate a dielectric barrier discharge by applying a pulse voltage between the first discharge electrode 41 and the second discharge electrode 42 of the plasma reactor 11. As a result, plasma due to the dielectric barrier discharge is generated between the first discharge electrode 41 and the second discharge electrode 42. Along with this, active oxygen (active species) including ozone is generated. The temperature of the plasma reactor 11 at the time of plasma generation is 30 ° C. or lower (23 ° C. in this embodiment).

Next, the CPU 61 controls to drive the fan 13 and releases active oxygen including ozone generated in the plasma reactor 11 into the warehouse 2. As a result, the bacteria contained in the air A1 in the warehouse 2 (specifically, the bacteria floating in the warehouse 2 and the bacteria adhering to the crops in the warehouse 2) are sterilized by the contact with the active oxygen. Further, the contact with active oxygen inactivates the virus contained in the air A1 in the warehouse 2, and the ethylene generated from the agricultural products in the warehouse 2 is decomposed.

Further, when the fan 13 is driven, the air A1 in the warehouse 2 is taken into the air purifier 1 as the active oxygen is released into the warehouse 2. In this case, the air A1 taken into the air purifier 1 passes through the fan 13 and is guided to the plasma reactor 11. When the air A1 guided to the plasma reactor 11 passes through the through hole 31 of the ceramic substrate 20, bacteria and viruses contained in the air A1 are electrostatically collected by the first discharge electrode 41 and the second discharge electrode 42. .. Then, the bacteria are sterilized and the virus is inactivated by the electric shock caused by the dielectric barrier discharge. Further, the collision of cations contained in the plasma generated by the dielectric barrier discharge kills the bacteria, inactivates the virus, and decomposes ethylene contained in the air A1. In addition, the contact of active oxygen generated by the dielectric barrier discharge kills the bacteria and inactivates the virus. Some of the bacteria and viruses are burned by the heat generated in the dielectric barrier discharge. After that, a part of the generated active oxygen, the bacteria are sterilized, the virus is inactivated, and the air A1 in which ethylene is decomposed is released into the warehouse 2.

When the ozone released from the air purifier 1 fills the warehouse 2, the ozone concentration in the warehouse 2 reaches a concentration that adversely affects workers and agricultural products. Therefore, in the present embodiment, the ozone concentration is monitored by using the ozone concentration sensor 54, and when the permissible value is exceeded, the power applied to the plasma reactor 11 and the output of the fan 13 are limited to limit the inside of the warehouse 2. It controls to reduce the ozone concentration of the plasma.

More specifically, in the CPU 61, when the ozone concentration detection signal output from the ozone concentration sensor 54 is input, the ozone concentration indicated by the ozone concentration detection signal is an allowable value (in the present embodiment, it is an environmental standard value of 0. It is determined whether or not it exceeds 1 ppm). Then, when it is determined that the ozone concentration exceeds the permissible value, the CPU 61 controls to reduce the electric power applied to the plasma reactor 11. For example, the CPU 61 of the present embodiment controls to reduce the voltage applied between the first discharge electrode 41 and the second discharge electrode 42 from 9 kV to 6 kV. In the present embodiment, when the ozone concentration exceeds the permissible value, the voltage applied between the first discharge electrode 41 and the second discharge electrode 42 is controlled to be reduced, but the first discharge electrode 41 The voltage applied between the second discharge electrode 42 and the second discharge electrode 42 may be cut off (reduced to 0 kV). At the same time, the CPU 61 controls to reduce the output of the fan 13 (in the present embodiment, the drive voltage of the fan 13). In the present embodiment, when the ozone concentration exceeds the permissible value, the drive voltage of the fan 13 is controlled to be lowered, but the drive voltage of the fan 13 is cut off (reduced to 0 V). May be good. As a result, the amount of ozone generated in the plasma reactor 11 is reduced, and the amount of ozone released into the warehouse 2 is reduced, so that the ozone concentration in the warehouse 2 is reduced.

Then, when the ozone concentration in the warehouse 2 decreases and it is determined that the ozone concentration is equal to or lower than the permissible value, the CPU 61 controls to restore the electric power applied to the plasma reactor 11 and outputs the fan 13. Performs undo control. Further, the CPU 61 outputs a display signal to the operation panel 71, and controls the display screen of the operation panel 71 to display an illustration or characters indicating that entry into the warehouse 2 is permitted.

Next, a method for manufacturing the plasma reactor 11 will be described.

First, the first and second ceramic green sheets 81 and 82 to be the dielectric 23 are formed by using a ceramic material containing alumina powder as a main component (see FIGS. 10 and 11). As a method for forming the ceramic green sheets 81 and 82, a well-known molding method such as tape molding or extrusion molding can be used. Then, each of the ceramic green sheets 81 and 82 is punched to form a hole 83 to be a through hole 31. Further, the four corners of the second ceramic green sheet 82 are punched to form cutouts 84 that expose the pad portions 35 and 36. The hole 83 and the notch 84 may be formed by laser machining, drilling, or the like.

Next, the first ceramic green sheet 81 is placed on a support base (not shown). Further, a conductive paste (tungsten paste in this embodiment) is printed on the main surface 85 of the first ceramic green sheet 81 by using a conventionally known paste printing apparatus (not shown). As a result, an unfired electrode 86 having a thickness of 10 μm, which serves as a discharge electrode 41, 42, a connecting portion 43, 44, and a pad portion 35, 36, is formed on the main surface 85 of the first ceramic green sheet 81. As a printing method of the unfired electrode 86 on the first ceramic green sheet 81, a well-known printing method such as screen printing can be used.

Then, after the conductive paste is dried, the second ceramic green sheet 82 is laminated on the main surface 85 of the first ceramic green sheet 81 on which the unfired electrode 86 is printed, and a pressing force is applied in the sheet laminating direction. .. As a result, the ceramic green sheets 81 and 82 are integrated to form a ceramic laminate. Next, after performing a drying step, a degreasing step, etc. according to a well-known method, a predetermined temperature (for example, about 1400 ° C. to 1600 ° C.) at which alumina and tungsten can sinter the ceramic green sheets 81, 82 and the unfired electrode 86. ) Is fired at the same time. As a result, the alumina in the first and second ceramic green sheets 81 and 82 and the tungsten in the conductive paste were simultaneously sintered, and the dielectric 23, the discharge electrodes 41 and 42, the connecting portions 43 and 44 and the pad were simultaneously sintered. The portions 35 and 36 are formed by simultaneous firing, and the first and second ceramic green sheets 81 and 82 form the ceramic substrate 20. After that, the first wiring is connected to the first pad portion 35, and the second wiring is connected to the second pad portion 36. Through the above process, the plasma reactor 11 is completed.

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

(1) Conventionally, it has been proposed to form a plasma reactor by alternately stacking an electrode panel having a built-in discharge electrode and a spacer for forming a space between adjacent electrode panels. However, in this case, there is a problem that an increase in the number of parts and man-hours constituting the plasma reactor is unavoidable, leading to an increase in manufacturing cost.

On the other hand, in the air purifier 1 of the present embodiment, the first discharge electrode 41 and the second discharge electrode 42 for generating plasma and the through hole 31 through which the air A1 to be purified by plasma passes are formed in one ceramic substrate 20. Since it is formed, the plasma reactor 11 can be configured without using a plurality of ceramic substrates 20. Therefore, the manufacturing cost of the plasma reactor 11 can be significantly reduced. Further, the capacitance of the plasma reactor 11 is smaller than that in the case where the plasma reactor 11 is composed of a plurality of ceramic substrates 20. As a result, it is not necessary to apply a large amount of electric power when driving the plasma reactor 11, so that the power consumption can be suppressed. Further, in the present embodiment, since plasma is generated by the electric discharge across the through hole 31, the plasma reaches the entire through hole 31. As a result, the air A1 passing through the through hole 31 can be reliably purified.

(2) In the present embodiment, in addition to plasma contact, bacteria are sterilized and viruses are inactivated by electric shock due to dielectric barrier discharge and contact with active species including ozone. Further, in the present embodiment, ethylene decomposition is carried out not only by contacting plasma but also by contacting active species containing ozone. Therefore, even if the processing amount of the air A1 increases, it is not necessary to apply a high voltage between the discharge electrodes 41 and 42 (inside the through hole 31), and the increase in the power consumption of the plasma reactor 11 can be suppressed. Moreover, since it is not necessary to increase the size of the plasma reactor 11 in order to enable the application of a high voltage into the through hole 31, the size of the air purifier 1 can be reduced.

(3) In the present embodiment, the first discharge electrode 41 and the second discharge electrode 42 are arranged in the central portion of the ceramic substrate 20, and the first pad portion 35 and the second pad portion 36 are the outer peripheral portions of the ceramic substrate 20 (specifically). They are arranged at the four corners of the ceramic substrate 20). Therefore, since the discharge electrodes 41 and 42 and the pad portions 35 and 36 can be arranged apart from each other, it is possible to avoid an abnormal discharge generated between the discharge electrodes 41 and 42 and the pad portions 35 and 36.

[Second Embodiment]
Hereinafter, a second embodiment embodying the present invention will be described with reference to the drawings. Here, the parts different from the first embodiment will be mainly described. In this embodiment, the structure of the plasma reactor is different from that of the first embodiment.

More specifically, as shown in FIGS. 13 and 14, the plasma reactor 91 of the present embodiment is configured by laminating a plurality of ceramic substrates 92 in the substrate thickness direction. Each ceramic substrate 92 includes a through-hole conductor 94 that penetrates the first ceramic insulating layer 93 in the thickness direction. The upstream end (left side in FIG. 14) of the through-hole conductor 94 is electrically connected to the pad portion 95, and the downstream end (right side in FIG. 14) of the through-hole conductor is a ceramic substrate 92. It is exposed on the second main surface 96 of.

Further, the plasma reactor 91 is formed with an electrically conductive portion 97 that conducts the ceramic substrates 92 with each other. The electrically conductive portion 97 of the present embodiment is made of a cured product of a conductive metal paste. Further, the electrical conduction portion 97 has a function of fixing and holding the ceramic substrates 92 to each other. Specifically, the electrically conductive portion 97 is filled between a pair of ceramic substrates 92 adjacent to each other. More specifically, the electrically conductive portion 97 is formed by the second main surface 96 of the predetermined ceramic substrate 92, the surface of the pad portion 95 provided on the ceramic substrate 92 adjacent to the downstream side, and the inner surface 99 of the notch portion 98. It is filled in the enclosed space. The electrically conductive portion 97 is electrically connected to the end surface of the through-hole conductor 94 exposed on the second main surface 96 and the surface of the pad portion 95. As a result, the pad portions 95 of the adjacent ceramic substrates 92 are electrically connected to each other via the electrically conductive portion 97 and the through-hole conductor 94. The end face 100 of the ceramic substrate 92 is exposed without being covered by the electrically conductive portion 97.

Therefore, in the present embodiment, by stacking a plurality of ceramic substrates 92 in the substrate thickness direction, the amount of plasma generated is further increased, so that the air A1 passing through the through hole 101 (through portion) is purified more efficiently. can do. Further, when a plurality of ceramic substrates 92 are laminated, the number of parts constituting the plasma reactor 91 increases, which may lead to an increase in manufacturing cost. However, in the present embodiment, it is not necessary to interpose a spacer for securing a passage space for the air A1 between the adjacent ceramic substrates 92, so that even if a plurality of ceramic substrates 92 are laminated, the manufacturing cost increases. Can be suppressed. Moreover, since the step of interposing a spacer is not required, the plasma reactor 91 can be easily manufactured.

In addition, each of the above-mentioned embodiments may be changed as follows.

-In each of the above embodiments, both the first discharge electrode 41 and the second discharge electrode 42 are in an unexposed state on the inner wall surfaces of the through holes 31 and 101. However, either one of the first discharge electrode 41 and the second discharge electrode 42 may be exposed on the inner wall surface of the through holes 31 and 101, or the first discharge electrode 41 and the second discharge electrode 42 may be exposed. Both may be exposed on the inner wall surface of the through holes 31 and 101.

-In each of the above embodiments, the first discharge electrode 41 and the second discharge electrode 42 are embedded at the same depth inside the ceramic substrates 20 and 92, but have different depths inside the ceramic substrates 20 and 92. It may be buried in. For example, the ceramic substrate is composed of the first to third ceramic insulating layers, the first discharge electrode is formed on the surface of the first ceramic insulating layer, and the second discharge electrode is formed on the surface of the second ceramic insulating layer. It may be formed on top.

As shown in the plasma reactor 111 of FIG. 15, the first discharge electrode 112 and the second discharge electrode 113 are layered electrodes extending in the plane direction of the substrate and provided on the main surface 115 of the ceramic substrate 114. , It may be covered with a protective layer (not shown) made of a dielectric. In this case, the first discharge electrode 112 and the second discharge electrode 113 are exposed to the outside of the ceramic substrate 114. However, since the first discharge electrode 112 and the second discharge electrode 113 are coated with a protective layer, it is possible to prevent the discharge electrodes 112 and 113 from being consumed due to discharge. Examples of the dielectric constituting the protective layer include glass and alumina.

The plasma reactor 111 is formed as follows. First, a ceramic green sheet to be a ceramic substrate 114 is formed by using a ceramic material containing alumina powder as a main component. Then, each ceramic green sheet is punched to form a hole portion to be a through hole 116 (through portion). Next, the ceramic green sheet is placed on the support base. Further, a conductive paste (here, tungsten paste) is printed on the main surface of the ceramic green sheet using a paste printing apparatus. As a result, unfired electrodes serving as discharge electrodes 112 and 113, connecting portions 117 and pad portions 118 are formed on the main surface of the ceramic green sheet. Then, after the conductive paste is dried, a dielectric (here, alumina) serving as a protective layer is coated so as to cover the unfired electrode. Next, after performing a drying step and a degreasing step according to a well-known method, the ceramic green sheet, the unfired electrode and the dielectric are heated to a predetermined temperature (about 1400 ° C to 1600 ° C) at which alumina and tungsten can be sintered. Simultaneous firing is performed. As a result, the plasma reactor 111 is completed.

In the second embodiment, the electric conductive portions 97 that hold the plurality of ceramic substrates 92 fixedly to each other are provided on the second main surface 96 of the predetermined ceramic substrate 92 and the pads adjacent to the ceramic substrate 92 on the downstream side. The space surrounded by the surface of the portion 95 and the inner surface 99 of the notch portion 98 was filled. The end face 100 of the ceramic substrate 92 was exposed without being covered by the electrically conductive portion 97. However, as shown in FIG. 16, the electrically conductive portion 121 has a second main surface 123 of a predetermined ceramic substrate 122, a surface of a pad portion 124 provided on the ceramic substrate 122 adjacent to the downstream side, and a notch portion. The space surrounded by the inner surface 125 of the ceramic substrate 122 may be filled and the end surface 126 of each ceramic substrate 122 may be covered.

-In each of the above embodiments, when the ozone concentration measured by the ozone concentration sensor 54 exceeds the permissible value, the power applied to the plasma reactors 11 and 91 is controlled to be reduced, and the output of the fan 13 is reduced. I was in control. However, when the ozone concentration exceeds the permissible value, only the control for reducing the electric power applied to the plasma reactors 11 and 91 may be performed, or only the control for reducing the output of the fan 13 may be performed. Further, when the ozone concentration exceeds the permissible value, control may be performed to sound an alarm, or control may be performed to display a character indicating the warning on the display screen of the operation panel 71. Further, when the ozone concentration exceeds the permissible value, the ventilation fan (not shown) of the warehouse 2 may be driven, or the window of the warehouse 2 (not shown) may be opened. May be good. Further, when the ozone concentration exceeds the permissible value, the door (not shown) of the warehouse 2 may be locked.

-Although the ozone concentration sensor 54 of each of the above embodiments is arranged in the lower region 5 of the apparatus main body 3, it may be arranged in another place. For example, the ozone concentration sensor 54 may be arranged between the plasma reactors 11 and 91 constituting the air purifier 1 and the fan 13, or may be arranged in the warehouse 2 (for example, the wall portion 72). good. Further, a plurality of ozone concentration sensors 54 may be provided. In this case, the CPU 61 may calculate, for example, the average value of the measured values measured by the respective ozone concentration sensors 54, and use the calculated average value as the ozone concentration in the warehouse 2. It is preferable that the ozone concentration sensors 54 are arranged at positions separated from each other. In this way, the ozone concentration in the warehouse 2 can be measured more accurately. Further, even if some of the ozone concentration sensors 54 fail, the ozone concentration can be reliably measured.

-In the air purifier 1 of each of the above embodiments, the fan 13 is arranged on the upstream side of the plasma reactors 11 and 91, but the fan 13 may be arranged on the downstream side of the plasma reactors 11 and 91.

-The plasma reactors 11 and 91 of each of the above embodiments were driven by using an AC power supply, but may be driven by using a pulse power supply. Even when a pulse power supply is used, the frequency is preferably 20 kHz or higher, which is higher than the audible range. By doing so, it is possible to reduce the noise generated when the plasma reactors 11 and 91 are driven.

-The apparatus main body 3 constituting the air purifier 1 of each of the above embodiments was installed on the floor portion 8 in the warehouse 2. However, the device main body 3 may be installed on the wall portion 72 or on the ceiling portion 9.

-The air purifier 1 of each of the above embodiments was used to sterilize bacteria, inactivate viruses, and decompose ethylene in a warehouse 2 for storing agricultural products. However, the air purifier 1 may be used for sterilizing bacteria, inactivating viruses, and decomposing ethylene in a greenhouse in which agricultural products are cultivated.

Further, as shown in FIG. 17, the air purifier 131 may be used for sterilizing bacteria, inactivating viruses, and decomposing ethylene in a container 132 for transporting agricultural products. The air purifier 131 is arranged near the outlet of the air A2 provided in the refrigerator 133 in the container 132. The power supply 134 for applying a voltage to the plasma reactor (not shown) is a battery. In this way, the power supply 134 can be miniaturized, so that the power supply 134 can be reliably installed in the container 132.

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 plasma reactor is characterized in that the substrate is a ceramic substrate.

(2) In the means 1, the plasma reactor is characterized in that the penetrating portion is a through hole opened in the pair of main surfaces.

(3) The plasma reactor according to the means 1, wherein neither the first discharge electrode nor the second discharge electrode alone surrounds the penetrating portion in a plan view of the substrate.

(4) In the means 1, the through portion is a plurality of arranged through holes, and the first discharge electrode and the second discharge electrode are arranged along the length direction of the plurality of through holes. A plasma reactor characterized by being arranged so as to extend.

1,131 ... Air purifier 11,91,111 ... Plasma reactor 12,134 ... Power supply 13 ... Fan 20, 92, 114, 122 as a blowing means ... Ceramic substrate as a substrate 21 ... First main surface as a main surface 22, 96, 123 ... Second main surface as the main surface 23 ... Dielectric 31, 101, 116 ... Through hole 33 as the penetrating portion ... First end portion 34 as the end portion of the penetrating portion 34 ... End portion of the penetrating portion 2nd end 41, 112 ... 1st discharge electrode 42, 113 ... 2nd discharge electrode 54 ... Ozone concentration sensor 61 ... CPU as a control means
115 ... Main surfaces A1, A2 ... Air

Claims (16)

A dielectric substrate having a pair of main surfaces and having a penetrating portion penetrating the pair of main surfaces, a first discharge electrode formed on the substrate, and a first discharge electrode formed on the substrate. In a plasma reactor equipped with a second discharge electrode having a different polarity from that of
The first discharge electrode and the second discharge electrode are layered electrodes that are arranged so as to sandwich the penetrating portion when viewed from a direction perpendicular to the main surface and extend in the surface direction of the main surface. ,
A plasma reactor characterized in that plasma is generated by a discharge generated between the first discharge electrode and the second discharge electrode across the penetrating portion. The plasma reactor according to claim 1, wherein at least one of the first discharge electrode and the second discharge electrode is in an unexposed state on the inner wall surface of the penetrating portion. The plasma reactor according to claim 1 or 2 , wherein the first discharge electrode and the second discharge electrode are layered electrodes embedded in a substrate. The plasma reactor according to any one of claims 1 to 3, wherein the first discharge electrode and the second discharge electrode are layered electrodes embedded at the same depth inside the substrate. The first discharge electrode and the second discharge electrode, the an electrode layered provided on the principal surface together when extending in the plane direction of the main surface of the substrate, covered with a protective layer made of a dielectric material The plasma reactor according to claim 1 or 2 , wherein the plasma reactor is characterized in that. The penetrating portion is a groove-shaped penetrating portion, and the first discharge electrode and the second discharge electrode are arranged so as to extend along the length direction of the groove-shaped penetrating portion. The plasma reactor according to any one of claims 1 to 5. A plurality of the groove-shaped penetrating portions are arranged in parallel, and the first discharge electrode and the second discharge electrode are alternately arranged along the width direction of the groove-shaped penetrating portion. The plasma reactor according to claim 6. The plasma reactor according to claim 6 or 7 , wherein the groove-shaped penetrating portion has a wide end portion. The plasma reactor according to any one of claims 1 to 8 , wherein the material of the first discharge electrode and the second discharge electrode is tungsten, and the material of the dielectric is alumina. The plasma reactor according to any one of claims 1 to 9 , wherein a plurality of the substrates are laminated in the substrate thickness direction. A plasma reactor according to any one of claims 1 to 1 0,
A power supply that applies a voltage to generate plasma in the plasma reactor, and
An air purifier comprising a blower means for flowing air through the penetrating portion and discharging ozone generated in the plasma reactor together with the air. An ozone concentration sensor that measures the ozone concentration and
Claim 1 is characterized by comprising a control means for controlling the reduction of the electric power applied to the plasma reactor from the power source when the ozone concentration measured by the ozone concentration sensor exceeds a permissible value. The air purifier according to 1. Wherein when the concentration of the ozone as measured by the ozone concentration sensor exceeds an allowable value, the air according to claim 1 2, characterized in that the control for reducing the output of said blowing means Purifier. The blowing means, the air purifier according to any one of claims 1 1 to 1 3, characterized in that it is disposed upstream of the plasma reactor. The plasma reactor, an air purifier according to any one of claims 1 1 to 1 4, characterized in that the center frequency of the voltage waveform is driven using the power of more than 20 kHz. Wherein the power source, an air cleaner according to any one of claims 1 1 to 1 5 characterized in that it is a battery.

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