Air purification device and air purification method

Abstract

To suppress degradation of the charging performance of an electret filter and enable the electret filter to be charged without preparing a recharging device for recharging the electret filter.SOLUTION: An air purification device 1 that charges airborne particles and collects them via corona discharge generated by the application of high voltage includes: a first discharge unit 35 which has conductivity, includes a first discharge electrode 25 and a first ground electrode 8, and charges airborne particles; an electret filter 9 which is disposed downstream in the airflow direction of the first discharge unit 35, and collects the charged airborne particles; and a second discharge unit 55 which has conductivity, includes a second discharge electrode 38 and a second ground electrode 39, and charges the electret filter 9.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an air purifying device and an air purifying method that charge and collect aerosol particles containing viruses and bacteria in the air, thereby purifying the air. [Background technology]

[0002] Aerosol particles (hereinafter referred to as "airborne particles" or simply "particles") including dust, dirt, viruses, and bacteria may be present and suspended in the air. Conventionally, air purifier technology has been known that charges and captures the particles in the air to purify the air, and in recent years, electret filters that combine low pressure loss (high breathability) and high collection efficiency have come to be used in the collection section of air purifiers.

[0003] For example, Patent Document 1 discloses a dust collecting device technology that includes a discharge section (needle-shaped discharge electrode) that charges particles in the air with corona discharge and a collection section (electret filter) that collects the particles charged by the discharge section, located downstream of the air flow direction of the blowing means. The electret filter of the collection section is a filter made of electrically charged nonwoven fabric, and since it collects particles using electrostatic force, it has a better balance between breathability (low pressure loss) and collection efficiency than general filters.

[0004] Furthermore, Patent Document 2 discloses a filter electrification treatment device and a filter electrification treatment method for restoring the deteriorated characteristics of an electret filter and recovering the dust collection rate when the electret filter is cleaned and reused after collecting dust for a certain period of time. Specifically, the document discloses a filter charging device and a filter charging method that are composed of a discharge section that charges particles that have been cleaned and purified by passing through an electret filter, and a drift electrode and a grid electrode for charging the electret filter. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2006-281135 A [Patent Document 2] JP 2015-13224 A Summary of the Invention [Problem to be solved by the invention]

[0006] The electret filter used as the collection part is an electret filter that has high breathability and high collection efficiency. However, there are problems such as the collection efficiency decreasing over time and the loss of charge when washed with a surfactant, which significantly reduces the collection performance.

[0007] However, the dust collector of Patent Document 1 does not include a charging unit (charging unit) for charging the electret filter in the dust collector. Therefore, in order to reuse an electret filter whose collection performance has decreased after cleaning an electret filter that has become dirty or worn over time, a recharging device such as that of Patent Document 2 must be separately prepared, which creates a problem of economic burden. In addition, Patent Document 2 is a filter charging device for charging an electret filter, and is not an air purifier that sucks in particles in the space and purifies it.

[0008] The present invention has been made to solve the above-mentioned problems, and has an object to provide an air purifying device and an air purifying method that make it possible to charge an electret filter serving as a collector in the air purifying device without the need for a separate recharging device for recharging the electret filter. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the first air purifying device of the present invention is an air purifying device that charges and collects particles in the air by corona discharge generated by application of high voltage, and is characterized by comprising: a first discharge section that is conductive and has a first discharge electrode and a first ground electrode to charge particles in the air; an electret filter that is arranged downstream of the first discharge section in the air flow direction and collects the charged particles in the air; and a second discharge section that is conductive and has a second discharge electrode and a second ground electrode to charge the electret filter.

[0010] According to the first air purifying device of the present invention, by providing a second discharge section (second discharge electrode and second ground electrode) capable of charging the electret filter within the air purifying device, the electret filter can be charged even when the air purifying device is in operation or at rest, which makes it possible to prevent the charging performance of the electret filter from decreasing over time or due to cleaning, and is economical because there is no need to prepare a separate recharging device for recharging the electret filter.

[0011] A second air purifying device of the present invention is the first air purifying device described above, further comprising a first support having conductivity and supporting the first discharge electrode, and a second support having conductivity and supporting the second discharge electrode, and it is preferable that the first support and the second support are integrally formed.

[0012] According to the second air purifier of the present invention, the support supporting the first discharge electrode and the second discharge electrode is integrally formed, and power can be fed to a single location, thereby reducing the number of components such as the high voltage generating unit and improving economy. Furthermore, when a high voltage is applied to the first discharge electrode during operation of the air purifier, a high voltage is also applied to the second discharge electrode, so that the electret filter can be charged even during operation, and charged particles can be collected while maintaining the collection performance of the electret.

[0013] A third air purifying device of the present invention is the above-mentioned second air purifying device, wherein the second support is preferably disposed at a position not blocking the air flow passage.

[0014] According to the third air purifying device of the present invention, the second support is not disposed in the air flow passage, and therefore the second discharge electrode can be supported without affecting the flowing air.

[0015] A fourth air purifying device of the present invention is the first air purifying device described above, wherein a number of openings are formed in the second grounding electrode, and the second grounding electrode and the electret filter are preferably arranged opposite each other in a direction blocking the air flow passage.

[0016] According to the fourth air purifying device of the present invention, the particles charged by the first discharge portion can be reliably collected by the electret filter after flowing through the second ground electrode.

[0017] A fifth air purifying device of the present invention is the first air purifying device described above, wherein the electret filter, the second support and the second grounding electrode are preferably formed in a cylindrical shape, and a plurality of the second discharge electrodes are arranged at regular intervals at the end of the second support downstream in the air flow direction.

[0018] According to the fifth air purifying device of the present invention, the second support and the second discharge electrode can generate a charged area around the entire periphery of the electret filter, thereby achieving stable charging (electrical charging) performance.

[0019] A sixth air purifying device of the present invention is the fifth air purifying device described above, wherein the electret filter, the second support, and the second ground electrode are preferably formed in a cylindrical shape, and the plurality of second discharge electrodes, the electret filter, and the second ground electrode are preferably arranged concentrically at positions corresponding to each other.

[0020] According to the sixth air purifying device of the present invention, the charged area generated on the electret filter can be made uniform, and the particles can be stably charged.

[0021] A seventh air purifying device of the present invention is the above-mentioned first air purifying device, wherein the first discharge electrode and the second discharge electrode are preferably formed by discharge electrodes having the same shape.

[0022] According to the seventh air purifying device of the present invention, the high voltage applied from the high voltage power supply unit can be made uniform, thereby realizing stable charging performance without causing abnormal discharge or the like.

[0023] An eighth air purifying device of the present invention is the seventh air purifying device described above, wherein the first discharge electrode and the second discharge electrode are preferably formed into a brush shape by bundling wire electrodes made of conductive fibers.

[0024] According to the eighth air purifying device of the present invention, a strong electric field corona discharge can be generated at a low voltage, and even if the discharging line electrode becomes unable to discharge due to dirt, another line electrode will start discharging due to the alternating effect, thereby achieving excellent durability.

[0025] A ninth air purifying device of the present invention is the above-mentioned first air purifying device, wherein a tip end of the second discharge electrode is preferably arranged to correspond to a central position in the width direction of the electret filter.

[0026] According to the ninth air purifying device of the present invention, the charged area generated between the tip of the second discharge electrode and the second ground electrode has an expanded diameter, so that the width of the electret filter can be utilized to the maximum extent possible.

[0027] A tenth air purifying device of the present invention is the above-mentioned first air purifying device, wherein the electret filter has a uniform thickness and is formed in a ring-like or flat plate-like shape.

[0028] According to the tenth air purifying device of the present invention, the electret filter is not pleated and has a uniform thickness, so that the electric field applied to the electret filter does not vary in strength, and the electret filter can be uniformly charged.

[0029] An eleventh air purifying device of the present invention is preferably the first air purifying device described above, further comprising a control unit that applies a high voltage to the second discharge unit when the electret filter is attached and the fan is stopped before starting operation.

[0030] According to the eleventh air purifying device of the present invention, an electret filter that has been washed to remove dirt loses its charge and its collection performance drops significantly. However, since the electret filter can be recharged before the start of operation, the electret filter can exhibit its original collection performance during operation and can reliably collect charged particles.

[0031] A twelfth air purifier of the present invention is preferably the first air purifier described above, further comprising a stop time measurement unit which measures a stop time from the end of operation, and a control unit which applies a high voltage to the second discharge unit with the fan stopped when the time measured by the stop time measurement unit reaches a preset recharging start time.

[0032] According to the twelfth air purifying device of the present invention, by periodically carrying out a recharging process, the electret filter can reliably collect charged particles during operation.

[0033] A thirteenth air purifier of the present invention is preferably the first air purifier described above, further comprising an operation time measurement unit which measures operation time, and a control unit which, when operation is stopped, continues to apply high voltage to the second discharge unit with the fan stopped if the operation time measured by the operation time measurement unit is shorter than a preset time.

[0034] According to the thirteenth air purifying device of the present invention, a high voltage can be applied to the electret filter at a proper recharging time at all times, so that the collection performance of the electret filter can be maintained.

[0035] A fourteenth air purifier of the present invention is preferably the first air purifier described above, further comprising an operation time measurement unit which measures an operation time, and a control unit which, when the fan is stopped during operation shutdown, changes a recharging time for applying a high voltage to the second discharge unit according to the operation time measured by the operation time measurement unit.

[0036] According to the fourteenth air purifying device of the present invention, by controlling the recharging time to be longer if the operating time is short and to be shorter if the operating time is long, it is possible to always apply a high voltage to the electret filter with an appropriate recharging time.

[0037] A fifteenth air purifying device of the present invention is preferably the first air purifying device described above, further comprising a high voltage power supply unit that controls the high voltage applied to the second discharge unit when the fan is stopped so that the high voltage is lower than the voltage at which abnormal discharge (spark) occurs.

[0038] According to the fifteenth air purifying device of the present invention, it is possible to recharge the electret filter while preventing damage to the filtering material of the electret filter.

[0039] The first air purification method of the present invention is an air purification method for charging and collecting particles in the air by corona discharge generated by application of high voltage, and is characterized by including a suction step of rotating a fan to suck in particles in the air, a particle charging step of applying a high voltage to charge particles in the air, and a collection step of collecting the particles while charging an electret filter.

[0040] According to the first air cleaning method of the present invention, particles can be captured while the electret filter is being charged, so dust can be collected while maintaining the collection performance of the electret filter.

[0041] The second air purification method of the present invention is the first air purification method described above, and preferably further includes a recharging step of charging the electret filter with the electret filter attached and the fan stopped before starting operation.

[0042] According to the second air purification method of the present invention, the electret filter is recharged before operation, so that the initial collection performance of the electret filter can be exhibited from the start of operation.

[0043] The third air purification method of the present invention is the first air purification method described above, and preferably further includes a recharging step of applying a high voltage to a discharge section to charge the electret filter after a preset predetermined time has elapsed with the electret filter attached and the fan stopped after the operation is completed.

[0044] According to the third air cleaning method of the present invention, the electret filter is recharged after a predetermined time has elapsed after the operation is stopped, so that the collection performance of the electret filter can be maintained. Effect of the Invention

[0045] According to the present invention, the electret filter can be charged while the air purifier is in operation or at rest, which makes it possible to prevent the charging performance of the electret filter from decreasing over time or due to cleaning, and also makes it possible to obtain various excellent effects, such as improving economy by eliminating the need to prepare a separate recharging device for recharging the electret filter. [Brief description of the drawings]

[0046] [Figure 1]FIG. 1 is a perspective view showing an air purifying device according to a first embodiment of the present invention, viewed obliquely from above. [Diagram 2] 1 is a perspective view showing the inside of an air purifying device according to a first embodiment of the present invention, viewed obliquely from above. [Diagram 3] 1 is a perspective view showing the inside of an air purifying device according to a first embodiment of the present invention, viewed obliquely from above. [Figure 4] FIG. 2 is a perspective view showing a support body of the air purifying device according to the first embodiment of the present invention, viewed obliquely from below. [Diagram 5] 1 is a cross-sectional side view of an air purifying device according to a first embodiment of the present invention. [Figure 6] FIG. 11 is a perspective view showing an air purifying device according to a second embodiment of the present invention, viewed obliquely from above. [Figure 7] FIG. 11 is a perspective view showing the inside of an air purifying device according to a second embodiment of the present invention, viewed obliquely from above. [Figure 8] FIG. 11 is a cross-sectional side view showing the periphery of a second discharge unit of an air purifying device according to a second embodiment of the present invention. [Figure 9] FIG. 11 is a perspective view showing a support body of an air purifying device according to a second embodiment of the present invention, viewed obliquely from below. [Figure 10] FIG. 2 is a block diagram showing devices that control the operation of the air purifying device according to the embodiment of the present invention. [Figure 11A] 4 is a flowchart showing the operation of the air purifying device according to the embodiment of the present invention. [Figure 11B] 4 is a flowchart showing the operation of the air purifying device according to the embodiment of the present invention. [Figure 12] 4 is a time chart showing the operation of the air purifying device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] Hereinafter, an air purifying device and an air purifying method according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the following description, the term "flow direction" refers to the direction in which air flows. Furthermore, the terms "upstream" and "downstream" and similar terms refer to "upstream" and "downstream" in the air flow direction and similar concepts.

[0048] [Description of the configuration of the air purifying device 1 according to the first embodiment] First, the configuration of an air purifying device 1 according to a first embodiment of the present invention will be described with reference to Fig. 1 to Fig. 5. Fig. 1 is a perspective view showing the air purifying device 1 from diagonally above, Fig. 2 is a perspective view showing the inside of the air purifying device 1 from diagonally above, Fig. 3 is a perspective view showing the inside of the air purifying device 1 from diagonally above, Fig. 4 is a perspective view showing supports (first support 24, second support 37, connecting portion 26) of the air purifying device 1 from diagonally below, and Fig. 5 is a cross-sectional view showing the air purifying device 1 from the side.

[0049] <Device body> The air purifying device 1 according to this embodiment is a device that collects particles in the air by charging them with corona discharge generated by application of high voltage, and includes a device body 2 having a flattened cylindrical shape as shown in Fig. 1. A circular air intake 3 is provided concentrically with the device body 2 on the top surface of the device body 2, and multiple slits 4 are arranged at intervals in the air intake 3 to prevent foreign matter from entering. In addition, multiple rectangular exhaust ports 5 are arranged at intervals in the circumferential direction on the side of the device body 2. The opening areas of the air intake 3 and the exhaust port 5 are appropriately set so that the wind speed of the air, etc., is an appropriate value.

[0050] In this embodiment, the air intake 3 is disposed at the top, but it may be disposed at the bottom upside down and the device body 2 may be attached to a ceiling surface, etc. Also, the exhaust vents 5 are disposed at regular intervals around the entire circumference of the side surface of the device body 2 so that clean air is discharged all around the side surface of the device body 2, but this is not limiting, and for example, they may be disposed so that clean air is discharged in two or four directions from the side surface of the device body 2.

[0051] Inside the device body 2, there are a top plate 6 and a base plate 7 arranged facing each other vertically, a fan 8 supported between the top plate 6 and the base plate 7, an electret filter (also called an electrostatic filter or electrostatic filter material) 9 which is cylindrically arranged to cover the outer periphery of the top plate 6 and the base plate 7, and a discharge unit 10 to which a high voltage is applied.

[0052] <Tabletop> The top plate 6 is circular and is disposed concentrically with the device body 2. An opening 11 is formed in the center of the top plate 6 at a position corresponding to the intake port 3. This opening 11 is provided at a position corresponding to an opening 16 of the fan 8 described later, and the edge of the opening 11 is bent in an R shape so that air can easily flow toward the fan 8. A rectangular intake pipe 12 is fixed to the lower center of the top plate 6. An opening is formed in the upper surface of the intake pipe 12 at a position corresponding to the intake port 3, and an opening is formed in the lower surface of the intake pipe 12 at a position corresponding to the opening 16 of the fan 8 described later.

[0053] <Base plate> The base plate 7 has the same circular shape as the top plate 6, and is disposed opposite the top plate 6. The base plate 7 is supported by the device body 2 by four pillars 13 provided inside the device body 2, and the top plate 6 and the base plate 7 are connected to each other by six pillars 14 disposed at regular intervals in the circumferential direction.

[0054] <Fan> The fan 8 as a grounding part (first grounding electrode) where the particles charged by the discharge part 10 are collected (adsorbed) is preferably a sirocco fan. The fan 8 has a number of blades 15 in the circumferential direction, and a cylindrical opening 16 is formed in the center of the fan 8. The fan 8 is provided between the top plate 6 and the base plate 7, and is arranged concentrically with the device body 2. The surface of the blades 15 of the fan 8 may be coated in advance with fluorine, Teflon (registered trademark), or the like to facilitate the release of the adsorbed particles. The blades 15 shown in FIG. 3 and the like are formed linearly in a plan view, but may have a curved shape. As shown clearly in FIG. 3, a plurality of guide vanes 33 for rectifying the airflow discharged from the fan 8 are radially provided on the outer periphery of the fan 8.

[0055] The motor 17 of the fan 8 is fixed below the base plate 7 via a flange 59. The motor shaft 18 penetrates the base plate 7 from below and is fixed to the bottom plate 19 of the fan 8 with a fastener 20. The motor 17 has a structure in which the motor shaft 18 and the housing 21 of the motor 17 are electrically connected to each other, and the blades 15, the bottom plate 19, the motor shaft 18, the housing 21 of the motor 17, and the device body 2 are electrically connected and electrically grounded. The entire fan 8 may be grounded, but it is sufficient that at least the blades 15 and the bottom plate 19 are conductive. For example, the bottom plate 19 or the motor shaft 18 may be provided with an earth brush (not shown) to be grounded. The fan may also be provided with blades 15 made of a composite material, and furthermore, only a part (tip) on the innermost periphery of the blades 15 may be conductive.

[0056] The fan 8 is not limited to a sirocco fan, and fans other than a sirocco fan, such as a turbo fan having a space in the center through which air can flow and a space through which air can flow out, can also be used.

[0057] <Electret filter> The electret filter 9 is formed in a cylindrical shape so as to cover the outer periphery of the top plate 6 and the base plate 7 at the outer periphery of the air straightening vane 33. The electret filter 9 has locking portions 22, 23 that are bent inward at the upper and lower parts, and the cross section of the electret filter 9 is formed in a U-shape. As shown in Figs. 3 and 5, a cylindrical second ground electrode 39 is disposed along the inner surface of the electret filter 9, and a large number of openings are formed in the second ground electrode 39. The electret filter 9 may be supported with platinum nanoparticles having an antiviral effect.

[0058] Moreover, the electret filter 9 is disposed so as to be separated largely from the outer periphery of the fan 8. By increasing the separation distance between the fan 8 and the electret filter 9, the area of ​​the electret filter 9 can be increased, and the passing wind speed inside the electret filter can be reduced, thereby improving the collection performance.

[0059] Generally, the electret filter 9 is made of a melt-blown polypropylene nonwoven fabric having a fiber diameter of about 1 to 20 μm, and is electretized by performing a charging process such as corona discharge (charging), which is a known technique. The surface charge of the electretized electret filter is polarized such that one side is a positive pole (plus pole) and the other side is a negative pole (minus pole) (see, for example, FIG. 8). The electret filter 9 is a filter having advantages of low pressure loss and high collection efficiency. On the other hand, the electret filter 9 needs to be removed from the air purifier 1 and washed because clogging occurs due to the particles being collected, but the charging performance is deactivated when washed with a surfactant, so that the electret filter 9 needs to be recharged. In addition, the charging performance of the electret filter 9 decreases over time, so that it needs to be recharged in this case as well. Therefore, in this embodiment, as described later, a mechanism is provided for recharging the electret filter 9 in the air purifier 1 during operation and during pause of the air purifier 1.

[0060] <Discharge section> The discharge section 10 is composed of a first discharge section 35 and a second discharge section 36. The first discharge section 35 is composed of a first discharge electrode 25 supported by a first support 24 to which a high voltage is applied, and the fan 8 as the first ground electrode as described above. The second discharge section 36 is composed of a second discharge electrode 38 supported by a second support 37 to which a high voltage is applied, and a second ground electrode 39.

[0061] The first support 24 is composed of a cylindrical annular portion 40 and a central portion 41 formed linearly along the center of the annular portion 40, and is electrically conductive. The second support 37 is formed in a concentric cylindrical shape on the outer periphery of the annular portion 40 of the first support 24, and is electrically conductive. The first support 24 and the second support 37 are integrally formed via a linear connecting portion 26 that passes through the centers of the first support 34 and the second support 37, and the connecting portion 42 is electrically conductive. The central portion 41 of the first support 24 extends downward from the center of the connecting portion 26 toward the center of the opening 16 of the fan 8.

[0062] The connecting portion 26 is disposed horizontally upstream of the fan 8 in the air flow direction, and is supported above the top plate 6 via insulators 28 at bilaterally symmetrical positions between the annular portion 40 of the first support 24 and the second support 37. The connecting portion 26 also penetrates the intake pipe 12 at two points, and insulating bushes 29 are attached to the points where the connecting portion 26 penetrates the intake pipe 12. By attaching the insulating bushes 29 in this manner, it is possible to insulate the first support 24 and the second support 37, to which a high voltage is applied, from the grounded intake pipe 12, and it is possible to prevent air that has flowed into the intake pipe 12 from the intake port 3 from leaking out of the intake pipe 12.

[0063] The first discharge electrodes 25 are attached to the lower end of the annular portion 40 and the lower end of the central portion 41 of the first support 24. A plurality of first discharge electrodes 25 (ten in FIG. 4) are arranged at predetermined intervals along the circumferential direction at the lower end of the annular portion 40, and one is arranged at the lower end of the central portion 41. The first discharge electrodes 25 attached to the lower end of the annular portion 40 and the plurality of blade portions 15 of the fan 8 are concentrically arranged at positions corresponding to each other, with one discharge electrode 25 for each of the two blade portions 15, so that a predetermined interval is maintained between the tip of each discharge electrode 25 and the tip of the blade portion 15 on the inner circumferential side. The first discharge electrode 25 is arranged so as to face downstream along the air flow direction (the direction of the dashed arrow in FIG. 5), so that it is unlikely to come into direct contact with particles in the air and is unlikely to become dirty.

[0064] The first discharge electrode 25 includes a bundle portion 31 formed in a brush shape by bundling a plurality of fibrous wire electrodes 30. One first discharge electrode 25 is formed by bundling, for example, approximately 100 wire electrodes 30. The first discharge electrode 25 may be formed by bundling 10 to 200 wire electrodes 30 each having a diameter of 5 to 25 μm. The first discharge electrode 25 does not necessarily have to have a brush-like shape, and may have other shapes, such as a projection shape or a needle shape.

[0065] The wire electrode 30 is made of non-magnetic stainless steel fibers with a diameter of 12 μm, and the stainless steel used is SUS304, which contains 18% Cr and 8% Ni, and is highly marketable, economical, and corrosion-resistant. Note that the wire electrode 30 may be made of other materials, such as SUS316, which contains 18% Cr, 12% Ni, and molybdenum (Mo), as long as the material is non-magnetic stainless steel. By using non-magnetic stainless steel fibers for the wire electrode 30 in this way, the wire electrode 30 can be easily separated from the bundle 31, and the discharge performance can be improved. For example, in the case of magnetic ferrite, it is difficult for the wire electrode to be separated from the bundle, so that the effect of electric field interference with the bundle is large, making it difficult to generate a corona discharge with a strong electric field.

[0066] The voltage applied to the first discharge electrode 25 is in the range of 4 to 6 kV, and the length of the first discharge electrode 25 is set in the range of 3 to 7 mm, so that stable discharge can be achieved. In addition, a negative high voltage is applied to the first discharge electrode 25 in the form of a direct current. By adopting the direct current method in this way, a relatively simple configuration can be achieved compared to other methods (alternating current, pulse), and by adopting the negative charging method, a larger discharge current can be passed through the first discharge electrode 25 in the same space (gap) compared to the positive charging method. Furthermore, discharge stability (characteristics that make it difficult for abnormal discharge to occur) can be improved compared to the positive charging method.

[0067] As clearly shown in Figure 5, the first discharge electrode 25 is housed in an opening 16 inside the fan 8 and is positioned so that a charged area EA is generated between the first discharge electrode 25 and the bottom plate 19 of the fan 8, and between the first discharge electrode 25 and the inner tips of the blade portions 15 of the fan 8.

[0068] The second discharge electrodes 38 are attached to the lower end of the second support 37, and a plurality of them (50 in FIG. 4) are arranged at predetermined intervals along the circumferential direction. The second discharge electrodes 38 are made of the same material and have the same number as the first discharge electrodes 25, and have the same brush-like shape, but are formed to be longer than the first discharge electrodes 25. As shown in FIG. 5, the second discharge electrodes 38 are arranged so that their tip portions are at the same height as the center position (position 1 / 2Y in FIGS. 5 and 8) of the electret filter 9 in the height direction (width direction).

[0069] [Description of the configuration of the air purifying device 50 according to the second embodiment] Next, the configuration of an air purifying device 50 according to a second embodiment of the present invention will be described with reference to Figs. 6 to 9. Fig. 6 is a perspective view showing the air purifying device 50 from diagonally above, Fig. 7 is a perspective view showing the inside of the air purifying device 50 from diagonally above, Fig. 8 is a cross-sectional view showing the periphery of the second discharge unit of the air purifying device 50 from the side, and Fig. 9 is a perspective view showing the supports (first support 24, second support 56, and connecting portion 42) of the air purifying device 50 from diagonally below. In the following description, the same reference numerals are used in Figs. 6 to 9 to designate the same components as those of the air purifying device 1 according to the first embodiment of the present invention, and detailed description thereof will be omitted.

[0070] In the air purifying device 50 according to this embodiment, a scroll 51 that houses a fan 8 is provided in the device body 2. A second ground electrode 52 and a flat electret filter 53 are disposed in the scroll 51 downstream of the fan 8 in the air flow direction. The second ground electrode 52 has a flat plate shape with a large number of flow holes formed therein, and is disposed on the inner surface side of the electret filter 53. That is, the electret filter 53 is disposed so as to be included in the charged area EA generated between the second discharge electrode 57 and the second ground electrode 52.

[0071] In the discharge section of the air purifying device 50, the second discharge section 55 has a different configuration from the second discharge section 36 of the air purifying device 1 according to the first embodiment described above, but the first discharge section 35 has a similar configuration to the first discharge section 35 of the air purifying device 1 according to the first embodiment described above, so a description thereof will be omitted. The second discharge section 55 has a second discharge electrode 57 supported by a second support 56 to which a high voltage is applied, and a second ground electrode 52.

[0072] The second support 56 is formed in a U-shape in a side view at the downstream end of the connecting portion 42, and is conductive. The second support 56 penetrates the top plate of the scroll 51, and an insulating bush 49 is attached to the penetration point.

[0073] The second discharge electrode 57 is disposed in parallel to and spaced from the electret filter 53, and a plurality of second discharge electrodes 57 (six in FIG. 9) are disposed at regular intervals on the lower end of the second support 56. The second discharge electrodes 57 are all the same in material, number, length, and number of bundles as the first discharge electrode 25, and have the same brush-like shape. As shown in FIG. 8, the second discharge electrode 57 is disposed so that its tip is at the same height as the center position of the electret filter 53 in the height direction. A rectangular exhaust port 58 is formed on the side of the device body 2, downstream of the second discharge electrode 57 in the air flow direction.

[0074] In the second embodiment described above, the second ground electrode 52, the electret filter 53, and the second discharge electrode 57 are arranged in that order from the upstream side in the air flow direction, but the second discharge electrode 57, the electret filter 53, and the second ground electrode 52 may be arranged in that order from the upstream side in the air flow direction.

[0075] [Air purification method using air purification device 1, 50] Next, an air purification method using the air purifying device 1, 50 according to an embodiment of the present invention will be described with reference to Figures 1 to 9 as well as Figures 10 to 12. Figure 10 is a block diagram showing devices that control the operation of the air purifying device 1, 50, Figures 11A and 11B are flowcharts showing the operation of the air purifying device 1, 50, and Figure 12 is a time chart showing the operation of the air purifying device 1, 50.

[0076] As shown in FIG. 10, the air purifier 1,50 is equipped with a control unit 60 having a memory 61 and a CPU 62, and this control unit 60 is connected via an interface 63 to a display unit 64, an operation unit 65, a filter detection unit 66, a replacement door detection unit 67, an operation time measurement unit 68, a stop time measurement unit 69, a high voltage power supply unit 70, etc.

[0077] The display unit 64 displays the operating state of the air purifying device 1, 50, the operation unit 65 has an operation switch and input keys, and the filter detection unit 66 is, for example, an optical sensor or a contact sensor, and detects whether the electret filter 9 is attached in the device 1, 50. The replacement door detection unit 67 is, for example, an optical sensor or a contact sensor, and detects whether the replacement door (not shown) of the electret filter 9 is open or closed.

[0078] If the electret filter 9 becomes dirty as the air purifier 1,50 is operated, it may become clogged. Therefore, before operation, the electret filter 9 is removed from the air purifier 1,50, washed, dried, and then attached to the air purifier 1,50. At this time, when the filter detection unit 66 detects that the electret filter 9 has been attached and the replacement door detection unit 67 detects that the replacement door has been closed, a recharging process is usually performed on the electret filter 9 before operation of the device 1,50. At this time, the display unit 44 of the control unit 60 may display selection buttons for "new" and "cleaned" and, when "new" is selected, the recharging process of the electret filter 9 may be omitted, and the recharging process may be performed only when "cleaned" is selected.

[0079] The operation time measurement unit 68 is a timer that measures the operation time of the air purifying device 1, 50, and the stop time measurement unit 69 is a timer that measures the stop time of the air purifying device 1, 50.

[0080] The motor drive unit 74 controls the motor 17 of the fan 8. The high voltage power supply unit 70 includes a high voltage generation unit 71 and a high voltage switching unit 72, and is configured to boost the voltage of an AC power supply 73 using a high voltage transformer, and then convert the AC current to DC in a voltage multiplier unit and further boost the voltage to generate a high voltage of several kV. The high voltage power supply unit 70 also functions as an output control unit for controlling the output of the high voltage applied to the first discharge electrode 25 and the second discharge electrodes 38, 57. The high voltage power supply unit 70 also controls switching between a plurality of high voltages (-V1, -V2) using the high voltage switching unit 72, and supplies high voltage to the supports (first support 24, second supports 37, 56, and connecting units 26, 42).

[0081] The air purifier 1, 50 may be provided with a differential pressure measuring unit that measures the differential pressure (clogging) of the electret filter 9, and a brushing device that brushes off dirt from the electret filter 9 when the differential pressure reaches a predetermined value.

[0082] As shown in S1 to S5 of Fig. 11A and Fig. 12, when the filter detection unit 66 (see Fig. 10) detects that the electret filter 9 has been installed in the device 1, 50 (see S1) and the replacement door detection unit 67 (see Fig. 10) detects that the replacement door has been closed (see S2), the high voltage power supply unit 70 applies a high voltage -V2 to the discharge unit 10, 54 to recharge the electret filter 9 (see S3). After that, when a predetermined time T1 (see Fig. 12) has elapsed, the high voltage power supply unit 70 stops applying the high voltage -V2 to the discharge unit 10, 54 (see S5).

[0083] In the next step S6, when the operation switch of the operation unit 65 (see FIG. 10) is turned ON and the air purifier 1, 50 enters the operation mode, the operation time measurement unit 68 (see FIG. 10) starts measuring the operation time of the air purifier 1, 50 (see S7), and the fan 8 rotates (see S8), and air containing particles generated in the external area is sucked into the device body 2 from the intake port 3 by the suction force of the fan 8 (see the dashed arrow indicating the air flow in FIG. 5). At this time, a high voltage -V1 is applied to the first discharge electrode 25 and the second discharge electrodes 38, 57 by the high voltage power supply unit 70 (see FIG. 10) via the supports (first support 24, second support 37, connecting unit 26) in the case of the first discharge unit 10, and via the supports (first support 24, second support 56, connecting unit 42) in the case of the second discharge unit 54, respectively (see S9).

[0084] When a high voltage is applied to the first discharge electrode 25 and the second discharge electrodes 38, 57, the tips of several wire electrodes 30 arranged on the outer periphery of the bundle 31 are separated from the bundle 31 and bent toward the ground electrode. Then, the wire electrodes 30 separated from the bundle 31 are in a strong electric field, and a corona discharge is generated between the tips of the wire electrodes 30 and the ground electrode.

[0085] Due to the corona discharge thus generated, in the first discharge section 10, cone-shaped charged areas EA are formed between the first discharge electrode 25 at the lower end of the center section 41 and the bottom plate 19 of the fan 8, between the multiple discharge electrodes 25 at the lower end of the annular section 40 and each of the inner circumferential tips of the multiple blade sections 15, and between the multiple discharge electrodes 25 at the lower end of the annular section 40 and the bottom plate 19 of the fan 8. In the second discharge sections 36, 55, cone-shaped charged areas EA are formed between the second discharge electrodes 38, 57 at the lower ends of the second supports 37, 56 and the second ground electrodes 39, 52.

[0086] As described above, in the operation mode of the air purifier 1, 50, air containing particles sucked into the device body 2 passes through the intake pipe 12 and passes through the charging area EA of the first discharge unit 35 at the opening 16 of the fan 8, so that the particles are negatively charged. Then, the particles charged by the first discharge electrode 25 are adsorbed and collected on the surface of the fan 8 including the blade portion 15 of the fan 8. Then, the particles adsorbed to the fan 8 electrostatically aggregate and become larger than a certain size, and are scattered again and collected by the electret filter 9, 53. Also, the particles that pass through the charging area EA of the second discharge unit 36 ​​and are negatively charged by the second discharge electrode 38, 57 are adsorbed and collected on the surface of the electret filter 9, 53. Then, the clean air from which the particles have been removed is discharged to the outside of the device body 2 through the exhaust port 5, 58.

[0087] In addition, when the second discharge electrode 38, 57 is negatively charged as described above, the surface potential of the electret filter 9, 53 on the second discharge electrode 38, 57 side becomes negative potential, and the surface potential of the electret filter 9, 53 on the opposite second ground electrode 39, 52 (GND) side becomes positive potential. Therefore, even if the particles are negatively charged at the first discharge electrode 25 and then the electret filter 9, 53 is negatively charged (charged with the same polarity as the first discharge electrode 25) at the second discharge electrode 38, 57, the electret filter 9, 53 (positive potential side) on the second ground electrode 39, 52 (GND) side can capture the negatively charged particles at the first discharge electrode 25 (see FIG. 8). In the present invention, a negative high voltage is applied to the first and second discharge parts 35, 36, 55 via the support body. However, if a positive high voltage is applied, the polarity will simply be reversed, and the principle of particle collection will remain the same.

[0088] Next, as shown in S10 to S13 in FIG. 11A and FIG. 12, when the operation switch of the operating unit 65 (see FIG. 10) is turned OFF to stop the air purifying device 1, 50, the application of high voltage is stopped, the rotation of the fan 8 is stopped, and measurement of the operation time of the air purifying device 1, 50 by the operation time measurement unit 68 is terminated.

[0089] In the next step S14, the control unit 60 determines whether or not the operation time of the air purifying device 1, 50 measured by the operation time measurement unit 68 has exceeded a predetermined time. If it is determined that the operation time has exceeded the predetermined time, the control unit 60 proceeds to step S15 in Fig. 11B, and if it is determined that the operation time has not exceeded the predetermined time, the control unit 60 proceeds to step S18 in Fig. 11B.

[0090] In S15 of Fig. 11B, the stop time measurement unit 69 starts measuring the operation stop time of the air purifier 1, 50, and in the next step S16, the control unit 60 judges whether the operation stop time has passed a predetermined time T3 (see Fig. 12). As a result, if the control unit 60 judges that the operation stop time has passed the predetermined time T3 (YES in S16), the operation stop time measured by the stop time measurement unit 69 is reset and the process proceeds to the next step S18. On the other hand, if the control unit 60 judges in step S16 that the operation stop time has not passed the predetermined time T3 (NO in S16), the control in step S16 is repeated until the operation stop time has passed the predetermined time T3.

[0091] In the next step S18, in order to recharge the electret filter 9, the high voltage power supply unit 70 (see FIG. 10) applies a high voltage -V2 to the first discharge electrode 25 and the second discharge electrodes 38, 57 via the supports (first support 24, second support 37, connecting portion 26) in the case of the first discharge unit 10, and via the supports (first support 24, second support 56, connecting portion 42) in the case of the second discharge unit 54. At this time, the recharging time for applying the high voltage to the first discharge unit 10 or the second discharge unit 54 may be changed according to the operation time measured by the operation time measurement unit 68.

[0092] Then, in the next step S19, the control unit 60 judges whether the application time of the high voltage -V2 in step S18 has passed the predetermined time T2 or T4. At this time, when the control unit 60 proceeds from step S14 to step S19 directly via S18, the control unit 60 judges whether the application time of the high voltage -V2 has passed the predetermined time T2 (see FIG. 12) or not, and when the control unit 60 proceeds from step S14 to step S19 via S15 to S18, the control unit 60 judges whether the operation time has passed the predetermined time T4 (see FIG. 12) or not. Then, when it is judged that the application time of the high voltage -V2 has passed the predetermined time T2 or T4, the application of the high voltage is stopped in the next step S20. On the other hand, when the control unit 60 judges that the application time has not passed the predetermined time T2 or T4 (NO in S16), the control unit 60 repeats the control in step S19 until the application time of the high voltage -V2 has passed the predetermined time T2 or T4. (Steps S11 to S20: Shows the post-operation electret filter charging process.)

[0093] Thereafter, when the operation switch of the operation unit 65 (see FIG. 10) is turned ON and the air purifier 1, 50 enters the operation mode (see S21), the process returns to step S7 described above, and the control from S7 onwards is repeated. On the other hand, if the operation switch of the operation unit 65 (see FIG. 10) is not turned ON, the process returns to step S15 described above, and the control from S15 onwards is repeated.

[0094] The above-described embodiment illustrates one aspect of the air purifying device and air purifying method according to the present invention, and the technical scope of the present invention is not limited to the above-described embodiment.

[0095] For example, in the air purifiers 1, 50 according to the first and second embodiments described above, a conductive support (power supply unit) is shared and a high voltage is applied simultaneously to the first discharge electrode 25 and the second discharge electrode 38, 57, but the present invention is not limited to this case. For example, a conductive power supply member may be fixed to a non-conductive support, for example, made of plastic, and a high voltage may be applied to each of the first discharge electrode 25 and the second discharge electrode 38, 57 via the respective power supply members. In this case, for example, in the case of a new electret filter 9 that does not require recharging, a high voltage does not necessarily have to be applied to the electret filter 9 while the air purifiers 1, 50 are in operation. (A high voltage may be applied to the first discharge electrode 25, and a high voltage may not be applied to the second discharge electrodes 38, 57.) Also, when the air purifier 1, 50 is at rest, a high voltage may be applied only to the electret filter 9 to recharge it. (A high voltage does not need to be applied to the first discharge electrode 25, and a high voltage is applied to the second discharge electrodes 38, 57.)

[0096] Furthermore, the mounting positions and configurations of first discharge electrode 25 and second discharge electrodes 38, 57 are not necessarily limited to those described above, so long as they are capable of charging attracted particles.

[0097] In the air purifier 1, 50 according to the above embodiment, the high voltage applied to the discharge part (support) when the fan 8 is stopped is higher than the high voltage applied to the discharge part (support) during operation and lower than the voltage at which abnormal discharge (spark) occurs, but it may be the same as the high voltage applied to the discharge part (support) during operation. Furthermore, the high voltage applied when recharging the electret filter 9 before and after operation (after operation) may be the same high voltage as during operation. Furthermore, for example, during operation of the air purifier 1, 50, a high voltage of about -6 KV (corresponding to -V1 in FIG. 12) may be applied to the first discharge electrode 25, which is the charging part, and a high voltage of about -8 KV (corresponding to -V2 in FIG. 12) may be applied to the second discharge electrode 38, 57, which charges the electret filter 9, which is the dust collecting part.

[0098] Furthermore, the air purifying device 1, 50 according to the above embodiment is provided with a mechanism for recharging the electret filter 9 even during operation and when at rest, but may further be provided with a mechanism for periodically recharging the electret filter 9 at preset intervals after operation when the rotation of the fan 8 is stopped and the electret filter 9 is attached. [Industrial Applicability]

[0099] INDUSTRIAL APPLICABILITY The present invention can be suitably used in home or commercial air purifying devices and air purifying methods that charge and collect aerosol particles containing viruses and bacteria in the air, and purify the air. [Explanation of symbols]

[0100] 1. Air purifier 8 Fan (first ground electrode) 9 Electret Filter 24 First Support 25 First discharge electrode 35 First discharge section 36 Second discharge section 37 Second Support 38 Second discharge electrode 39 Second ground electrode 52 Second ground electrode 55 Second discharge section 56 Second Support 57 Second discharge electrode 50 Air Purifier 60 Control section 68 Driving Time Measurement Unit 69 Stop Time Measurement Unit 70 High voltage power supply unit

Claims

1. An air purifying device that charges and collects particles in the air by corona discharge generated by application of high voltage, a first discharge section that is conductive, has a first discharge electrode and a first ground electrode, and charges particles in the air; an electret filter disposed downstream of the first discharge section in a direction of air flow, the electret filter collecting charged particles in the air; a second discharge section that is conductive, has a second discharge electrode and a second ground electrode, and charges the electret filter; An air purifying device comprising:

2. a first support having electrical conductivity and supporting the first discharge electrode; A conductive second support that supports the second discharge electrode, 2. The air purifying device according to claim 1, wherein the first support and the second support are integrally formed.

3. 3. The air purifying device according to claim 2, wherein the second support is disposed at a position not blocking an air flow passage.

4. The second ground electrode is formed with a number of openings, and the second ground electrode and the electret filter are disposed opposite each other in a direction blocking the air flow passage. The air purifying device according to claim 1 .

5. The air purifying device according to claim 2, characterized in that the electret filter, the second support, and the second ground electrode are formed in a cylindrical shape, and a plurality of the second discharge electrodes are arranged at regular intervals at an end of the second support downstream in the air flow direction.

6. The air purifying device according to claim 5, characterized in that the electret filter, the second support, and the second ground electrode are formed in a cylindrical shape, and the plurality of second discharge electrodes, the electret filter, and the second ground electrode are concentrically arranged at positions corresponding to each other.

7. 2. The air purifying device according to claim 1, wherein the first discharge electrode and the second discharge electrode are formed by discharge electrodes having the same shape.

8. 8. The air purifying device according to claim 7, wherein the first discharge electrode and the second discharge electrode are formed into a brush shape by bundling linear electrodes made of conductive fibers.

9. 2. The air purifying device according to claim 1, wherein a tip of the second discharge electrode is disposed so as to correspond to a center position in a width direction of the electret filter.

10. 2. The air purifying device according to claim 1, wherein the electret filter has a uniform thickness and is formed in a ring shape or a flat plate shape.

11. The air purifying device according to claim 1, further comprising a control unit that applies a high voltage to the second discharge unit when the electret filter is attached and the fan is stopped before starting operation.

12. A stop time measurement unit is provided to measure the stop time from the end of operation, 2. The air purifying device according to claim 1, further comprising a control unit that applies a high voltage to the second discharge unit while the fan is stopped when the time measured by the stop time measurement unit reaches a preset recharging start time.

13. A driving time measurement unit is provided for measuring driving time, 2. The air purifying device according to claim 1, further comprising a control unit that, when operation is stopped, continues to apply a high voltage to the second discharge unit while the fan is stopped if the operation time measured by the operation time measurement unit is shorter than a preset time.

14. A driving time measurement unit is provided for measuring driving time, 2. The air purifying device according to claim 1, further comprising a control unit that changes a recharging time for applying a high voltage to the second discharge unit in accordance with the operating time measured by the operating time measurement unit when the fan is stopped during an operation stop.

15. 2. The air purifying device according to claim 1, further comprising a high-voltage power supply unit that controls the high voltage applied to the second discharge unit when the fan is stopped so that the high voltage is lower than the voltage at which abnormal discharge (spark) occurs.

16. An air purification method in which particles in the air are charged and collected by corona discharge generated by application of a high voltage, a suction step of rotating a fan to suck in particles in the air; a particle charging step of charging particles in the air by applying a high voltage; a collecting step of collecting particles while charging the electret filter; An air purifying method comprising:

17. The air cleaning method according to claim 16, further comprising a recharging step of charging the electret filter with the electret filter attached and the fan stopped before starting operation.

18. 17. The air cleaning method according to claim 16, further comprising a post-operation electret filter charging step of applying a high voltage to a discharge unit to charge the electret filter after a preset time has elapsed with the electret filter attached and the fan stopped after the operation is completed.

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